Antimicrobial Aspects of Inflammatory Resolution in the ... · for example, that the skin ... the main pathways for SPM biosynthesis in the absence of ... in the eye, lung, and oral

of July 19, 2018.This information is current as

Proresolving MediatorsResolution in the Mucosa: A Role for Antimicrobial Aspects of Inflammatory

Eric L. Campbell, Charles N. Serhan and Sean P. Colgan

http://www.jimmunol.org/content/187/7/3475doi: 10.4049/jimmunol.1100150

2011; 187:3475-3481; ;J Immunol 

Referenceshttp://www.jimmunol.org/content/187/7/3475.full#ref-list-1

, 36 of which you can access for free at: cites 85 articlesThis article

        average*  

4 weeks from acceptance to publicationFast Publication! •    

Every submission reviewed by practicing scientistsNo Triage! •    

from submission to initial decisionRapid Reviews! 30 days* •    

Submit online. ?The JIWhy

Subscriptionhttp://jimmunol.org/subscription

is online at: The Journal of ImmunologyInformation about subscribing to

Permissionshttp://www.aai.org/About/Publications/JI/copyright.htmlSubmit copyright permission requests at:

Email Alertshttp://jimmunol.org/alertsReceive free email-alerts when new articles cite this article. Sign up at:

Print ISSN: 0022-1767 Online ISSN: 1550-6606. Immunologists, Inc. All rights reserved.Copyright © 2011 by The American Association of1451 Rockville Pike, Suite 650, Rockville, MD 20852The American Association of Immunologists, Inc.,

is published twice each month byThe Journal of Immunology

by guest on July 19, 2018http://w

ww

.jimm

unol.org/D

ownloaded from

by guest on July 19, 2018

http://ww

w.jim

munol.org/

Dow

nloaded from

Antimicrobial Aspects of Inflammatory Resolution in theMucosa: A Role for Proresolving MediatorsEric L. Campbell,* Charles N. Serhan,† and Sean P. Colgan*

Mucosal surfaces function as selectively permeable bar-riers between the host and the outside world. Giventheir close proximity to microbial Ags, mucosal surfaceshave evolved sophisticated mechanisms for maintaininghomeostasis and preventing excessive acute inflamma-tory reactions. The role attributed to epithelial cellswas historically limited to serving as a selective barrier;in recent years, numerous findings implicate an activerole of the epithelium with proresolving mediators inthe maintenance of immunological equilibrium. In thisbrief review, we highlight new evidence that the epithe-lium actively contributes to coordination and resolutionof inflammation, principally through the generation ofanti-inflammatory and proresolution lipid mediators.These autacoids, derived from v-6 and v-3 polyunsat-urated fatty acids, are implicated in the initiation, pro-gression, and resolution of acute inflammation anddisplay specific, epithelial-directed actions focusedon mucosal homeostasis. We also summarize presentknowledge of mechanisms for resolution via regulationof epithelial-derived antimicrobial peptides in responseto proresolving lipid mediators. The Journal ofImmunology, 2011, 187: 3475–3481.

The resolution of ongoing inflammation was histori-cally considered a passive act of the healing processwith dilution of proinflammatory chemical mediators

(1) and occurred independent of active biochemical pathways(1, 2). This view has changed in fundamental ways in the pastdecade. It is now appreciated that uncontrolled inflammationis a unifying component in many diseases, and new evidenceindicates that inflammatory resolution is a biosyntheticallyactive process (3). These new findings implicate a tissue de-cision process wherein acute inflammation, chronic inflam-mation, or inflammatory resolution hold the answers as to

what endogenous mechanisms control the magnitude andduration of the acute response, particularly as they relate tothe cardinal signs of inflammation (2, 4). It has now becomeevident that the resolution program of acute inflammationparticularly within mucosal surfaces remains to be uncovered,and that a complete understanding of these critical pathwayswill undoubtedly direct new therapeutic opportunities.Inflammation at mucosal surfaces provides a unique setting

for which to define resolution pathways. By their nature, mu-cosal surfaces interact with the environment and thereby themicrobial world in which we live. Important in this regard, themicrobiota of each mucosal surface is unique. It is estimated,for example, that the skin harbors 182 different bacterialspecies, whereas the large intestine may support as many as1220 different bacterial phylotypes (5). Given this diversityof microbiota, it is not surprising that humans have evolvedunique mechanisms to counteract regular microbial chal-lenges. Along these same lines, the timely resolution of on-going local inflammation has evolved to these ever-changingchallenges.We are only now beginning to appreciate the uniquefeatures and importance of these responses.In this brief review, we highlight recent discoveries that

impact the active resolution of mucosal inflammation. Giventheir founding role in active resolution mechanisms, wehave focused on the unique contributions of specializedproresolving mediators (SPMs), namely, the resolvins, lipid-derived mediators that are agonist dependent, temporallydistinct, and functionally carry novel potent mucosa-directedsignals (2).

Resolution-based pharmacology: a lesson from aspirin

Resolution of inflammation and return to tissue homeostasisis an exceptionally well-coordinated process. SPMs generatedduring the resolution phase of ongoing inflammation acti-vely stimulate restoration of tissue homeostasis (3). The firstresolvin, known today as resolvin E1 (RvE1), was identified in1999 as a potent and active initiator of resolution (4). In-

*Mucosal Inflammation Program, Department of Medicine, University of ColoradoSchool of Medicine, Aurora, CO 80045; and †Department of Anesthesiology, Perioper-ative and Pain Medicine, Center for Experimental Therapeutics and Reperfusion Injury,Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115

Received for publication May 20, 2011. Accepted for publication July 15, 2011.

E.L.C. is supported by a fellowship from the Crohn’s and Colitis Foundation of Amer-ica. The S.P.C. laboratory is supported by National Institutes of Health GrantsR37DK50189 and RO1HL60569. The C.N.S. laboratory is supported by NationalInstitutes of Health Grants R01GM038765 and R01DE019938.

The content of this publication is solely the responsibility of the authors and does notnecessarily represent the official views of the National Institute of Diabetes and Digestiveand Kidney Diseases; the National Institute of General Medical Sciences; the NationalHeart, Lung, and Blood Institute; the National Institute of Dental and CraniofacialResearch; or the National Institutes of Health.

Address correspondence and reprint requests to Dr. Eric L. Campbell, Mucosal Inflam-mation Program, University of Colorado Denver, Mail Stop B-146, 12700 East 19thAvenue, Aurora, CO 80045. E-mail address: [email protected]

Abbreviations used in this article: AA, arachidonic acid; ALPI, intestinal alkaline phos-phatase; ASA, acetylsalicylic acid; ATL, aspirin-triggered lipoxin; BPI, bactericidalpermeability-increasing protein; COX, cyclooxygenase; DHA, docosahexaenoic acid;EPA, eicosapentaenoic acid; LXA4, lipoxin A4 (5S,6R,15S-trihydroxytrihydroxy-7E,9E,11Z,13E-eicosatetraenoic acid); PMN, polymorphonuclear leukocyte, neutrophil;PUFA, polyunsaturated fatty acid; RvD1, resolvin D1; RvE1, resolvin E1 (5S,6R,15S-trihydroxy-7E,9E,11Z,13E-eicosatetraenoic acid); SPM, specialized proresolving mediator.

Copyright� 2011 by TheAmerican Association of Immunologists, Inc. 0022-1767/11/$16.00

www.jimmunol.org/cgi/doi/10.4049/jimmunol.1100150

by guest on July 19, 2018http://w

ww

.jimm

unol.org/D

ownloaded from

ordinate, unrestricted, acute inflammation is now acknowl-edged as an instigating factor, which, when unchecked, con-tributes to numerous chronic disease states, including cardio-vascular disease, metabolic disorders, and cancer. As such, anunderstanding of the pharmacology of anti-inflammationand endogenous proresolution has been a significant ven-ture (2).As a basic feature, cyclooxygenase-2 (COX-2) contributes

fundamentally to both inflammation and resolution (6, 7).COX-2 expression is rapidly induced at sites of inflammationand is a key enzyme in the generation of PGs, via its oxy-genase and peroxidase activities (7). In brief, after liberationof the v-6 fatty acid arachidonic acid (AA) from cell mem-branes via phospholipase A2, the oxygenase function ofCOX-2 catalyzes AA to PGG2 and subsequently to PGH2

via the peroxidase activity of the enzyme. Nonsteroidal anti-inflammatory drugs lower the amplitude of inflammation anddelay resolution (6, 8). Acetylsalicylic acid (ASA, aspirin),stands apart in that it inhibits proinflammatory signals andaccelerates resolution (9). ASA irreversibly acetylates COX-2on serine 516, rendering it incapable of converting AA toPGG2. In its acetylated state, ASA produces 15R-H(P)ETEand its peroxidase activity remains intact, resulting in for-mation of 15R-hydroxyeicosatetraenoate. Aside from ASA’santi-inflammatory action of inhibiting PG synthesis, 15R-hydroxyeicosatetraenoate is a precursor for proresolution 15-epi-lipoxins (10). Such aspirin-triggered lipoxins (ATLs) aremore resistant to metabolic inactivation than lipoxins (11)and also assert anti-inflammatory and proresolving activitiesin a wide range of inflammatory diseases (7, 8). In addition tothe arachidonate-derived lipoxins and ATLs, bioactive SPMsare also biosynthesized from the v-3 polyunsaturated fattyacids (PUFAs). Both eicosapentaenoic acid (EPA) and doco-sahexaenoic acid (DHA) are precursors in the biosynthesis ofboth aspirin-triggered forms of the E- and D-series resolvins.Of importance, lipoxygenases can initiate the biosynthesisof resolvins (both E- and D-series), as well as protectins andmaresins, without ASA treatment (3) (see Fig. 1). These arethe main pathways for SPM biosynthesis in the absence ofASA treatment. Other nonsteroidal anti-inflammatory drugs(i.e., indomethacin) can both block the biosynthesis of theaspirin-triggered forms of SPM and lead to enhanced for-mation of SPMs via the lipoxygenase routes involved in thebiosynthesis of specific SPMs. The biosynthesis of SPM hasrecently been reviewed in detail and those interested shouldsee Ref. 12.

Active resolution: biosynthesis of SPM

Resolution of acute, self-limited inflammation is distinct, bydefinition, from anti-inflammatory process (3). Proresolvingmediators restrict further infiltration of polymorphonuclearleukocyte (PMN, neutrophil) to sites of acute inflammationand promote resolution via enhancing clearance of apoptoticcells by macrophages (3). Importantly, proresolving mediatorsstimulate antimicrobial activities of epithelia (13, 14), aidinga return to tissue homeostasis. These are particularly relevantin the eye, lung, and oral epithelial surfaces. For example,RvE1 reduces ocular herpes simplex-induced inflammation(15); protectin D1 reduces ocular epithelial injury (16);resolvin D1 (RvD1), RvE1, and protectin D1 each reduceairway inflammation (17–20); and RvE1 reduces oral in-

flammation of the periodontium (21) and stimulates theclearance of apoptotic cell from mucosal surfaces (22). Theprotective role of RvE1 in periodontal disease has been at-tributed to both diminished inflammation and curtailedosteoclast-dependent destruction of bone (23). In the gastro-intestinal tract, RvE1 is protective in murine models of colitis(13, 24–26). Moreover, RvE1 and RvD1 have been recentlyimplicated in the alleviation of inflammatory pain (27). Thus,the potential therapeutic benefits of SPMs are far-reaching.Much recent attention has been paid to understanding the

innate mechanisms involved in the resolution of inflamma-tion at mucosal sites. The best understood are the families oflipid mediators termed the resolvins and the maresins (2). Re-solvins have been studied in most detail and are v-3 PUFA-derived lipid mediators central to activation of the inflamma-tory resolution program (2, 3). The discovery of resolvins waspermitted by using an unbiased systems approach to acutecontained self-limited/naturally resolving inflammatory exu-dates using liquid chromatography-mass spectrometry-massspectrometry–based lipidemics and earlier knowledge thatv-3 PUFAs are beneficial to a number of cardiovascular andimmunoregulatory responses (9). Ensuing studies revealed theexistence of novel families of lipid mediators, derived fromeither EPA (C20:5, 18-series resolvins), as well as DHA (C22:6,17-series resolvins), which potently and stereoselectively ini-

FIGURE 1. “Class switching” in the lipid metabolome promotes reso-

lution. Enzymes COX-1 and COX-2 convert AA to PGG2 by cyclo-

oxygenation, and subsequently to PGH2 by peroxidation. In turn, PGH2 is

metabolized to PGs and thromboxanes via specific synthases (top panel). ASA-mediated acetylation of COX enzymes inhibits the cyclooxygenation in

COX-1, but COX-2 retains activity (see Refs. 4 and 87 for further details).

Proresolving SPMs are produced via acetylated COX-2 with substrates

AA and the v substrates EPA and DHA (bottom panel). Lipoxygenases inhuman, mouse, and fish tissues can also initiate the biosynthesis of 17S-

containing resolvins and protectins de novo.

3476 BRIEF REVIEWS: ANTIMICROBIALS AND INFLAMMATORY RESOLUTION

by guest on July 19, 2018http://w

ww

.jimm

unol.org/D

ownloaded from

tiate and enhance the resolution mechanisms in acute inflam-mation.

Mechanisms of SPM-mediated resolution

To date, an array of SPMs has been identified with potentproresolution activities; their mechanisms of action are equallydiverse. ATL (15-epi-lipoxin) binds to the lipoxin A4 (LXA4)receptor (ALX/FPR2; Formyl Peptide Receptor 2), elicitingantagonistic activities on PMN chemotaxis (28). RvE1 binds toand interacts with ChemR23 receptor, resulting in ERK andAKT phosphorylation and subsequent signal transduction viaribosomal protein S6 to enhance macrophage phagocytosis(29). RvE1 also binds to the LTB4 receptor BLT1 on neu-trophils, where it acts as a partial agonist (30). Aside from sig-nal transduction directly affecting leukocyte function, modu-lation of gene expression in response to SPM has revealed keyinsight to their mechanism of resolution. LXA4 and RvE1 in-duce CCR5 expression on the surface of apoptotic PMN andT cells, resulting in sequestration of CCL3/CCL5 in murineperitonitis, facilitating resolution (31). RvE1 and RvD1 bothattenuate PMN transmigration across endothelia (32, 33).Furthermore, RvE1 accelerates the clearance apically adherentPMN from epithelia by enhancing antiadhesive CD55 ex-pression (22). Likewise, ATL induces the expression of anantimicrobial peptide, bactericidal-permeability enhancing, inepithelial cells (14). Also, resolvin D2 (7S,8R,17S-trihydroxy-4Z,9E,11E,13Z,15E,19Z-docosahexaenoic acid) enhances phago-cyte killing of microbes, improving survival in cecal ligationpuncture-initiated sepsis (34), and RvD1 modulates macro-phage responses to LPS-TLR4 signaling, resulting in decreasedproinflammatory cytokine release, whereas maintaining IL-10expression (35).More recently, RvE1 was discovered to upregulate the ex-

pression of intestinal alkaline phosphatase (ALPI), a markerof differentiation with a surprising role in maintenance ofbacterial homeostasis (13). Given the proximity of mucosalsurfaces to bacterial Ags and the vital role of antimicrobialpeptides in host defense, we will discuss the potential role forantimicrobial peptides in the process of resolution.

Antimicrobial peptides in the mucosa

Epithelial cells are uniquely positioned to serve as a direct lineof communication between the immune system and the ex-ternal environment. In their normal state, mucosal surfacesare exposed on the lumenal surface to high concentrationsof foreign Ags, whereas at the same time, they are intimatelyassociated with the immune system via subepithelial lymphoidtissue (36). Polarized epithelia form a physical selective barrierto allow absorption/secretion whereas preventing entry ofpathogens into the body. The mucosal epithelium comprisesa heterogeneous population of differentiated epithelia withdistinct functions: absorptive enterocytes, mucus-secretinggoblet cells, antimicrobial peptide-secreting Paneth cells, andenteroendocrine cells (37).Antimicrobial peptides are secreted prophylactically by the

epithelium into the viscous mucus layer, thus minimizing theinstance of epithelium-adhering bacteria. Similarly, Panethcells secrete antimicrobial peptides (defensins/lectins) main-taining intestinal crypt sterility. Consequently, the epitheliumforms an important barrier, preventing the free mixing oflumenal antigenic material with the lamina propria, which

houses the mucosal immune system (38), and defects in thesedefensive functions contribute to disease pathogenesis (e.g.,loss of function in mucin-2/Paneth cells can contribute toinflammatory bowel disease) (39). Concordantly, antimicro-bial peptide generation provides protection for other mucosalepithelial surfaces: lung epithelia produce defensins and LL-37 (40), corneal and conjunctival epithelia express LL-37(41), and oral epithelia are protected by antimicrobial pep-tides secreted in saliva (42, 43).Like many aspects of immunology, the view that the epi-

thelium is merely a physical selective barrier has changed. Theepithelium is now viewed as an active player in normal ho-meostatic mechanisms of mucosal immunity, and in someinstances, the epithelium may centrally orchestrate mucosalinnate immunity and inflammation (44).

“Classical” antimicrobial peptides

The classically viewed antimicrobial peptides represent a di-verse array of small peptides (12–50 aa), containing a positivecharge and an amphipathic structure. The most studied an-timicrobial peptides to date are cathelicidins and defensins.Cathelicidin (LL-37) is expressed by epithelial cells, neu-trophils, monocytes, and macrophages, and can stimulate che-motaxis via the ALX/FPR2 receptor on these cells (45).Posttranslational processing is essential for its antimicrobialactivity in vivo (46) and is accomplished by serine proteasessuch as kallikreins (47) or PMN proteases such as proteinase-3(48). LL-37 antimicrobial activity was originally thoughtto neutralize endotoxin because of its cationic/amphipathiccapacities to interact with anionic LPS or prevent LPS bind-ing to CD14 (49). Aside from preventing sepsis by interferingwith the ability of LPS to stimulate TLR4 signaling, LL-37have subsequently been demonstrated to directly dampen proin-flammatory signaling initiated by LPS (50). Mice deficient inthe only known murine cathelicidin (encoded by the geneCnlp) show significant increases in susceptibility to a number ofmucosal infections (51).Defensins are cationic antimicrobial peptides broadly classed

as a- and b-defensins, the former predominantly expressed byPMN and Paneth cells, and the latter by epithelia (52). Similarto LL-37s, a-defensins are activated by proteolytic processingof an inactive precursor (53) and are stored in granules ofPMN. In contrast with a-defensins, b-defensins typically haveshort N-terminal extensions, and all possess some measure ofantimicrobial activity in their full-length forms. Defensins havebroad antimicrobial actions on Gram-positive and -negativebacteria, and defects in defensin expression have been shown tocontribute to a number of mucosal inflammatory diseases, in-cluding inflammatory bowel disease and necrotizing enteroco-litis (54). b-Defensins are secreted in saliva and are thought tobe protective against periodontitis and caries (43). Mutations ofthe 39-untranslated region of b-defensin lead to chronic andaggressive periodontitis (55).

Immunomodulatory functions of antimicrobial peptides.Given theirname, antimicrobial peptides were originally thought to func-tion merely as “natural antibiotics,” specialized in the killing ofbacteria. This bias has hampered discovery of their diverse arrayof function in immunity and their regulation in host defense.Increasing evidence indicates that aside from their antimicrobialactivity, antimicrobial peptides canmodulate immune responsesby inducing cytokine/chemokine production, inhibiting LPS-

The Journal of Immunology 3477

by guest on July 19, 2018http://w

ww

.jimm

unol.org/D

ownloaded from

induced proinflammatory cytokine production, promotingwound healing, and modulating the responses of dendriticcells or T cells. As such, antimicrobial peptides may be viewedas bridging the gap between innate and adaptive immunity.Cathelicidin has immunomodulatory functions; for instance,

it is chemotactic to mast cells and PMN via interaction with theALX/FPR2 receptor (45, 56), which is blocked by the anti-inflammatory LXA4 stable analog. Cathelicidin stimulates re-lease of the anti-inflammatory PGD2 from mast cells (57),which as mentioned earlier can prime tissues for resolution byexpressing enzymes necessary for resolution. Human b-defen-sin 2 also possesses immunomodulatory functions and, like LL-37, is known to be chemotactic for mast cells and activatedPMN (58). b-Defensin 3 upregulates COX-2 and PGE2 bio-synthesis in gingival fibroblasts (59). b-Defensins antagonizeT cell tissue infiltration and promote exfiltration (60, 61).Considering their rapid release in response to “danger signals”and their consequent immunomodulatory activities has led tothe concept that antimicrobial peptides can act as early warningsignals for infection and the creation of term alarmins (62).

Antimicrobial peptides and restitution/wound closure. As part oftheir proresolving activity, both LL-37 (63, 64) and b-defensin2 (65) are known to promote epithelial cell migration, neces-sary for mucosal restitution after physical injury or damagefrom immune activity. Human b-defensin 2 stimulates migra-tion and proliferation and tube formation of endothelialcells in wounds, resulting in neovascularization and acceleratedwound healing (66). LL-37 has been proposed to initiatetissue remodeling via matrix metalloproteinase activity andpromote wound closure via induction of the Snail/Slugtranscription factors, necessary for E-cadherin transcriptionand epithelial adherens junction formation (64).

“Nonclassical” antimicrobial peptides

Bactericidal permeability-increasing protein. A number of addi-tional mechanisms exist to maintain homeostasis at mucosalsurfaces. Among the innate antimicrobial defense moleculesof humans is bactericidal permeability-increasing protein(BPI), a 55- to 60-kDa protein originally found in neutro-phil azurophilic granules, on the neutrophil cell surface and,to a lesser extent, in specific granules of eosinophils (67).Subsequently, BPI was found to be expressed in epithelialcells (14). Based on an original transcriptional profiling ap-proach to identify novel ATL-regulated genes in intestinalepithelial cells, BPI was found to be expressed in both humanand murine epithelial cells of wide origin (oral, pulmonary, andgastrointestinal mucosa), and each was similarly regulated byATL. Functional studies using a BPI-neutralizing antiserumrevealed that surface-localized BPI blocks endotoxin-mediatedsignaling in epithelia and kills Salmonella typhimurium. Morerecently, molecular studies revealed that epithelial BPI isselectively induced by ATL and prominently regulated by thetranscription factors Sp1/3 and C/EBPb (68). Additionalstudies in human and murine tissue ex vivo revealed that BPIis diffusely expressed along the crypt-villous axis (14, 68), andthat epithelial BPI protein levels decrease along the lengthof the intestine (69). More recent studies with SPM have re-vealed the expression of BPI in various mucosal epithelia (67).As its name infers, BPI selectively exerts multiple antimi-

crobial actions against Gram-negative bacteria, including cy-

totoxicity through damage to bacterial inner/outer membranes,

neutralization of bacterial LPS (endotoxin), as well as servingas an opsonin for phagocytosis of Gram-negative bacteria byneutrophils (70, 71). The high affinity of BPI for the lipid Aregion of LPS (72) targets its cytotoxic activity to Gram-negative bacteria. Binding of BPI to the Gram-negative bac-terial outer membrane is followed by a time-dependent pene-tration of the molecule to the bacterial inner membrane wheredamage results in loss of membrane integrity, dissipation ofelectrochemical gradients, and bacterial death (73). BPI bindsthe lipid A region of LPS with high affinity (74, 75), andthereby prevents its interaction with other (proinflammatory)LPS-binding molecules, including LBP and CD14 (76). Be-cause BPI binds the lipid A region common to all LPSs, it isable to neutralize endotoxin from a broad array of Gram-negative pathogens (71). The selective and potent action ofBPI against Gram-negative bacteria and their LPS is fullymanifest in biologic fluids, including plasma, serum, and wholeblood (71, 77). In multiple animal models of Gram-negativesepsis and/or endotoxemia, administration of BPI congenersis associated with improved outcome (78, 79). These studies inepithelia have identified a previously unappreciated “molecularshield” for protection of mucosal surfaces against Gram-negative bacteria and their endotoxin.

ALPI. There is much recent interest in ALPI, a 70-kDa, GPI-anchored protein expressed on the apical (luminal) aspect ofintestinal epithelial cell (80). In the past, this molecule had beenviewed as one of the better epithelial differentiation markers,with little understanding of the true function of this moleculewithin the mucosa. More recent studies have identified thismolecule as a central player in microbial homeostasis (81–83).A recentmicroarray screen to identifyRvE1-regulatedgenes in

intestinal epithelial cells revealed two important findings. First,these studies revealed the previously unappreciated native ex-pression of the RvE1 receptor ChemR23 on epithelial cells. Ascreen of various epithelial cell lines revealed prominent ex-pression of ChemR23 on human intestinal epithelial cell lines(T84 and Caco-2). Unique was the pattern of expression onpolarized epithelia. This analysis revealed that ChemR23localizes predominantly to the apical membrane surface, whichwas somewhat unexpected given that most other G protein-coupled receptors exhibit basolateral expression in polarizedepithelia (84). Such membrane distribution of ChemR23 sug-gested that the localized generation of RvE1 during PMN–epithelial interactions could occur at the apical (lumenal) aspectof the tissue. This is an intriguing possibility given that theother known function for RvE1 on mucosal epithelia is topromote the termination and clearance of PMN after trans-migration (22), through well-characterized, CD55-dependentmechanisms (85, 86). Thus, the PMN–epithelial interactionsthat occur within the lumen of the intestine may initiate aproresolving signature to the epithelium during PMN transitthrough the mucosa.Second, these microarray studies identified a prominent

RvE1-dependent antimicrobial signature within the epithe-lium, including the induction of BPI and the BPI-like mol-ecule PLUNC (palate, lung, nasal epithelium clone) (13). Alsonotable was the induction of epithelial ALPI by RvE1.Surface-expressed ALPI was shown to retard Gram-negativebacterial growth and to potently neutralize LPS througha mechanism involving dephosphorylation of 1,49-bisphos-phorylated glucosamine disaccharide of LPS lipid A (82, 83).

3478 BRIEF REVIEWS: ANTIMICROBIALS AND INFLAMMATORY RESOLUTION

by guest on July 19, 2018http://w

ww

.jimm

unol.org/D

ownloaded from

This observation was translated to the murine model dextransodium sulfate colitis and revealed that induction of ALPI byRvE1 in vivo strongly correlated with the resolution phase ofinflammation (Fig. 2). Moreover, inhibition of ALPI activitywas shown to increase the severity of colitic disease and ab-rogate the protective influences of RvE1 (13). Like thosedefining epithelial expression of BPI (14), these studies pro-vide an example of the critical interface between inflammatoryresolution and the importance of antimicrobial mechanisms.

ConclusionsGiven the close proximity of bacteria to mucosal surfaces,maintenance of tissue homeostasis presents a significant chal-lenge. After successful handling of infiltrating bacteria, thegeneration of proresolving mediators accelerates the return tohomeostasis. This review highlights not only the multifunc-tional role of antimicrobial peptides in inflammation, but alsothe interdependent relationship between the induction ofantimicrobial peptides and the initiation of resolution path-

FIGURE 2. RvE1 biosynthesis and

model for induction of epithelial ALPI.

A, De novo synthesis of RvE1 at the

mucosal surface. During epithelial cell–

PMN interactions, RvE1 production is

amplified by transcellular biosynthesis

via the interactions of two or more cell

types, each contributing an enzymatic

product. In the example shown here,

epithelial cell COX-2 generates 18-

HEPE from dietary EPA and PMN-

expressed 5-lipoxygenase (5-LO), and

lta4H then generates RvE1 (see Refs. 34

and 88 for further details). Such locally

generated RvE1 is then made available to

activate apically expressed ChemR23,

which, in turn, induces the expression of

ALPI. Original magnification 3200. B,Induction of ALPI activity after in vivo

administration of RvE1 during the res-

olution of inflammation of a mouse

model of dextran sodium sulfate (DSS)

colitis [see Campbell et al. (13)]. Origi-

nal magnification 3400.

FIGURE 3. Temporal regulation andmultifunctional roles of SPM-regulated antimicrobial peptides in the resolution of inflammation. After microbial detection,

classical antimicrobial peptides are released by epithelial cells and recruited immune cells. Antimicrobial peptides aid in the killing of bacteria, stimulating PMNs to

generate reactive oxygen species (with inadvertent tissue damage), and promote further release of antimicrobial peptides and proinflammatory and anti-in-

flammatory lipid mediators via COX-2 induction and acetylation. In the resolution phase, generation of SPM elicits the induction of “nonclassical” antimicrobial

peptides such as ALPI and BPI (13, 14), which accelerate return to homeostasis via continued bacterial killing, and inhibition of LPS signaling (35). Furthermore,

SPMs can block and/or counteract the release of “classical” antimicrobial peptides from leukocytes, dampening the “Alarmin” signals (45).

The Journal of Immunology 3479

by guest on July 19, 2018http://w

ww

.jimm

unol.org/D

ownloaded from

ways and the role of resolvins in this process (see Fig. 3). Aftermicrobial detection, “alarmins” or “classical” antimicrobialpeptides are released by infiltrating immune cells, aiding thekilling of bacteria, stimulating neutrophils to generate reactiveoxygen species (with inadvertent tissue damage), promotingfurther release of antimicrobial peptides, and releasing bothproinflammatory and anti-inflammatory lipids via COX-2induction. As such, “classical” antimicrobial peptides couldbe considered to have both proinflammatory and anti-inflammatory properties, suggesting that antimicrobial pep-tides prime the inflammatory microenvironment of themucosal surface for resolution. After generation of SPM,“nonclassical” antimicrobial peptides may accelerate return tohomeostasis via continued bacterial killing, inhibition of LPSsignaling, and inhibition of “classical” antimicrobial peptiderelease from leukocytes. As such, it would appear that aninterdependent relationship exists between the activity ofantimicrobial peptides and the initiation of resolution pro-grams. Along these lines, RvE1 blocks LTB4-stimulated re-lease of LL-37 by human PMN, and LXA4 inhibits proin-flammatory actions of LL-37 (45).Overall, the contribution of microbes to health and disease

has provided an elegant lesson in biology. Results from modeldisease systems and humans allowed the discovery of pro-resolving mechanisms that are fundamental to our un-derstanding of disease pathogenesis. As summarized in thisreview, the interdependence of antimicrobial defense mecha-nisms with inflammatory disease resolution has provided aninformative example of how these biochemical pathways yieldinsight toward a better understanding of tissue function.Ongoing studies of antimicrobial regulation in the mucosa,exemplified by SPM-regulated BPI and ALPI in intestinalepithelia, should provide templates for the design of new andeffective therapies for inflammatory disease resolution.

DisclosuresS.P.C. and C.N.S. are inventors on patents assigned to Brigham and Women’s

Hospital-Partners HealthCare on the composition, uses, and clinical develop-

ment of anti-inflammatory and proresolving mediators and related compounds.

The following are licensed for clinical development: lipoxins to Bayer Health-

Care and resolvins and related materials to Resolvyx Pharmaceuticals. C.N.S.

retains founder stock in Resolvyx. E.L.C. has no financial conflicts of interest.

References1. Majno, G., and I. Joris. 1996. Cells, Tissues and Disease: Principles of General Pa-

thology. Blackwell Science, Cambridge, MA.2. Serhan, C. N., and N. Chiang. 2008. Endogenous pro-resolving and anti-

inflammatory lipid mediators: a new pharmacologic genus. Br. J. Pharmacol. 153(Suppl. 1): S200–S215.

3. Serhan, C. N., N. Chiang, and T. E. Van Dyke. 2008. Resolving inflammation:dual anti-inflammatory and pro-resolution lipid mediators. Nat. Rev. Immunol. 8:349–361.

4. Serhan, C. N., C. B. Clish, J. Brannon, S. P. Colgan, N. Chiang, and K. Gronert.2000. Novel functional sets of lipid-derived mediators with antiinflammatoryactions generated from omega-3 fatty acids via cyclooxygenase 2-nonsteroidalantiinflammatory drugs and transcellular processing. J. Exp. Med. 192: 1197–1204.

5. Bik, E. M. 2009. Composition and function of the human-associated microbiota.Nutr. Rev. 67(Suppl. 2): S164–S171.

6. Gilroy, D. W., P. R. Colville-Nash, D. Willis, J. Chivers, M. J. Paul-Clark, andD. A. Willoughby. 1999. Inducible cyclooxygenase may have anti-inflammatoryproperties. Nat. Med. 5: 698–701.

7. Spite, M., and C. N. Serhan. 2010. Novel lipid mediators promote resolution ofacute inflammation: impact of aspirin and statins. Circ. Res. 107: 1170–1184.

8. Schwab, J. M., N. Chiang, M. Arita, and C. N. Serhan. 2007. Resolvin E1 andprotectin D1 activate inflammation-resolution programmes. Nature 447: 869–874.

9. Serhan, C. N., S. D. Brain, C. D. Buckley, D. W. Gilroy, C. Haslett, L. A. O’Neill,M. Perretti, A. G. Rossi, and J. L. Wallace. 2007. Resolution of inflammation: stateof the art, definitions and terms. FASEB J. 21: 325–332.

10. Claria, J., and C. N. Serhan. 1995. Aspirin triggers previously undescribed bioactiveeicosanoids by human endothelial cell-leukocyte interactions. Proc. Natl. Acad. Sci.USA 92: 9475–9479.

11. Serhan, C. N., J. F. Maddox, N. A. Petasis, I. Akritopoulou-Zanze, A. Papayianni,H. R. Brady, S. P. Colgan, and J. L. Madara. 1995. Design of lipoxin A4 stableanalogs that block transmigration and adhesion of human neutrophils. Biochemistry34: 14609–14615.

12. Bannenberg, G., and C. N. Serhan. 2010. Specialized pro-resolving lipid mediatorsin the inflammatory response: an update. Biochim. Biophys. Acta 1801: 1260–1273.

13. Campbell, E. L., C. F. MacManus, D. J. Kominsky, S. Keely, L. E. Glover,B. E. Bowers, M. Scully, W. J. Bruyninckx, and S. P. Colgan. 2010. Resolvin E1-induced intestinal alkaline phosphatase promotes resolution of inflammationthrough LPS detoxification. Proc. Natl. Acad. Sci. USA 107: 14298–14303.

14. Canny, G., O. Levy, G. T. Furuta, S. Narravula-Alipati, R. B. Sisson, C. N. Serhan,and S. P. Colgan. 2002. Lipid mediator-induced expression of bactericidal/permeability-increasing protein (BPI) in human mucosal epithelia. Proc. Natl.Acad. Sci. USA 99: 3902–3907.

15. Rajasagi, N. K., P. B. Reddy, A. Suryawanshi, S. Mulik, P. Gjorstrup, andB. T. Rouse. 2011. Controlling herpes simplex virus-induced ocular inflammatorylesions with the lipid-derived mediator resolvin E1. J. Immunol. 186: 1735–1746.

16. Gronert, K., N. Maheshwari, N. Khan, I. R. Hassan, M. Dunn, and M. LaniadoSchwartzman. 2005. A role for the mouse 12/15-lipoxygenase pathway in promotingepithelial wound healing and host defense. J. Biol. Chem. 280: 15267–15278.

17. Aoki, H., T. Hisada, T. Ishizuka, M. Utsugi, T. Kawata, Y. Shimizu, F. Okajima,K. Dobashi, and M. Mori. 2008. Resolvin E1 dampens airway inflammation andhyperresponsiveness in a murine model of asthma. Biochem. Biophys. Res. Commun.367: 509–515.

18. Haworth, O., M. Cernadas, R. Yang, C. N. Serhan, and B. D. Levy. 2008. ResolvinE1 regulates interleukin 23, interferon-gamma and lipoxin A4 to promote theresolution of allergic airway inflammation. Nat. Immunol. 9: 873–879.

19. Levy, B. D., P. Kohli, K. Gotlinger, O. Haworth, S. Hong, S. Kazani, E. Israel,K. J. Haley, and C. N. Serhan. 2007. Protectin D1 is generated in asthma anddampens airway inflammation and hyperresponsiveness. J. Immunol. 178: 496–502.

20. Wang, B., X. Gong, J. Y. Wan, L. Zhang, Z. Zhang, H. Z. Li, and S. Min. 2011.Resolvin D1 protects mice from LPS-induced acute lung injury. Pulm. Pharmacol.Ther. 24: 434–441.

21. Hasturk, H., A. Kantarci, E.Goguet-Surmenian, A. Blackwood, C. Andry, C.N. Serhan,and T. E. Van Dyke. 2007. Resolvin E1 regulates inflammation at the cellular and tissuelevel and restores tissue homeostasis in vivo. J. Immunol. 179: 7021–7029.

22. Campbell, E. L., N. A. Louis, S. E. Tomassetti, G. O. Canny, M. Arita,C. N. Serhan, and S. P. Colgan. 2007. Resolvin E1 promotes mucosal surfaceclearance of neutrophils: a new paradigm for inflammatory resolution. FASEB J. 21:3162–3170.

23. Hasturk, H., A. Kantarci, T. Ohira, M. Arita, N. Ebrahimi, N. Chiang,N. A. Petasis, B. D. Levy, C. N. Serhan, and T. E. Van Dyke. 2006. RvE1 protectsfrom local inflammation and osteoclast- mediated bone destruction in periodontitis.FASEB J. 20: 401–403.

24. Arita, M., M. Yoshida, S. Hong, E. Tjonahen, J. N. Glickman, N. A. Petasis,R. S. Blumberg, and C. N. Serhan. 2005. Resolvin E1, an endogenous lipid me-diator derived from omega-3 eicosapentaenoic acid, protects against 2,4,6-trini-trobenzene sulfonic acid-induced colitis. Proc. Natl. Acad. Sci. USA 102: 7671–7676.

25. Bento, A. F., R. F. Claudino, R. C. Dutra, R. Marcon, and J. B. Calixto. 2011.Omega-3 fatty acid-derived mediators 17(R)-hydroxy docosahexaenoic acid, aspirin-triggered resolvin D1 and resolvin D2 prevent experimental colitis in mice. J.Immunol. 187: 1957–1969.

26. Lima-Garcia, J., R. Dutra, K. da Silva, E. Motta, M. Campos, and J. Calixto. Theprecursor of resolvin D series and aspirin-triggered resolvin D1 display anti-hyperalgesic properties in adjuvant-induced arthritis in rats. Br. J. Pharmacol. In press.

27. Xu, Z. Z., L. Zhang, T. Liu, J. Y. Park, T. Berta, R. Yang, C. N. Serhan, and R. R.Ji. 2010. Resolvins RvE1 and RvD1 attenuate inflammatory pain via central andperipheral actions. Nat. Med. 16: 592–597, 1p following 597.

28. Takano, T., S. Fiore, J. F. Maddox, H. R. Brady, N. A. Petasis, and C. N. Serhan.1997. Aspirin-triggered 15-epi-lipoxin A4 (LXA4) and LXA4 stable analogues arepotent inhibitors of acute inflammation: evidence for anti-inflammatory receptors. J.Exp. Med. 185: 1693–1704.

29. Ohira, T., M. Arita, K. Omori, A. Recchiuti, T. E. Van Dyke, and C. N. Serhan.2010. Resolvin E1 receptor activation signals phosphorylation and phagocytosis. J.Biol. Chem. 285: 3451–3461.

30. Arita, M., T. Ohira, Y. P. Sun, S. Elangovan, N. Chiang, and C. N. Serhan. 2007.Resolvin E1 selectively interacts with leukotriene B4 receptor BLT1 and ChemR23to regulate inflammation. J. Immunol. 178: 3912–3917.

31. Ariel, A., G. Fredman, Y. P. Sun, A. Kantarci, T. E. Van Dyke, A. D. Luster, andC. N. Serhan. 2006. Apoptotic neutrophils and T cells sequester chemokines duringimmune response resolution through modulation of CCR5 expression. Nat.Immunol. 7: 1209–1216.

32. Serhan, C. N., S. Hong, K. Gronert, S. P. Colgan, P. R. Devchand, G. Mirick, andR. L. Moussignac. 2002. Resolvins: a family of bioactive products of omega-3 fattyacid transformation circuits initiated by aspirin treatment that counter proin-flammation signals. J. Exp. Med. 196: 1025–1037.

33. Sun, Y. P., S. F. Oh, J. Uddin, R. Yang, K. Gotlinger, E. Campbell, S. P. Colgan,N. A. Petasis, and C. N. Serhan. 2007. Resolvin D1 and its aspirin-triggered 17Repimer. Stereochemical assignments, anti-inflammatory properties, and enzymaticinactivation. J. Biol. Chem. 282: 9323–9334.

34. Spite, M., L. V. Norling, L. Summers, R. Yang, D. Cooper, N. A. Petasis,R. J. Flower, M. Perretti, and C. N. Serhan. 2009. Resolvin D2 is a potent regulatorof leukocytes and controls microbial sepsis. Nature 461: 1287–1291.

3480 BRIEF REVIEWS: ANTIMICROBIALS AND INFLAMMATORY RESOLUTION

by guest on July 19, 2018http://w

ww

.jimm

unol.org/D

ownloaded from

35. Palmer, C. D., C. J. Mancuso, J. P. Weiss, C. N. Serhan, E. C. Guinan, andO. Levy. 17(R)-Resolvin D1 differentially regulates TLR4-mediated responses ofprimary human macrophages to purified LPS and live E. coli. J. Leukoc. Biol. In press.

36. Beagley, K. W., and A. J. Husband. 1998. Intraepithelial lymphocytes: origins,distribution, and function. Crit. Rev. Immunol. 18: 237–254.

37. Laukoetter, M. G., P. Nava, and A. Nusrat. 2008. Role of the intestinal barrier ininflammatory bowel disease. World J. Gastroenterol. 14: 401–407.

38. McCole, D. F., and K. E. Barrett. 2007. Varied role of the gut epithelium inmucosal homeostasis. Curr. Opin. Gastroenterol. 23: 647–654.

39. Kim, Y. S., and S. B. Ho. 2010. Intestinal goblet cells and mucins in health anddisease: recent insights and progress. Curr. Gastroenterol. Rep. 12: 319–330.

40. Singh, P. K., H. P. Jia, K. Wiles, J. Hesselberth, L. Liu, B. A. Conway,E. P. Greenberg, E. V. Valore, M. J. Welsh, T. Ganz, et al. 1998. Production of beta-defensins by human airway epithelia. Proc. Natl. Acad. Sci. USA 95: 14961–14966.

41. Gordon, Y. J., L. C. Huang, E. G. Romanowski, K. A. Yates, R. J. Proske, andA. M. McDermott. 2005. Human cathelicidin (LL-37), a multifunctional peptide,is expressed by ocular surface epithelia and has potent antibacterial and antiviralactivity. Curr. Eye Res. 30: 385–394.

42. Sahasrabudhe, K. S., J. R. Kimball, T. H. Morton, A. Weinberg, and B. A. Dale.2000. Expression of the antimicrobial peptide, human beta-defensin 1, in duct cellsof minor salivary glands and detection in saliva. J. Dent. Res. 79: 1669–1674.

43. Abiko, Y., M. Nishimura, and T. Kaku. 2003. Defensins in saliva and the salivaryglands. Med. Electron Microsc. 36: 247–252.

44. Shale, M., and S. Ghosh. 2009. How intestinal epithelial cells tolerise dendritic cellsand its relevance to inflammatory bowel disease. Gut 58: 1291–1299.

45. Wan, M., C. Godson, P. J. Guiry, B. Agerberth, and J. Z. Haeggstrom. 2011.Leukotriene B4/antimicrobial peptide LL-37 proinflammatory circuits are mediatedby BLT1 and FPR2/ALX and are counterregulated by lipoxin A4 and resolvin E1.FASEB J. 25: 1697–1705.

46. Cole, A. M., J. Shi, A. Ceccarelli, Y. H. Kim, A. Park, and T. Ganz. 2001. In-hibition of neutrophil elastase prevents cathelicidin activation and impairs clearanceof bacteria from wounds. Blood 97: 297–304.

47. Yamasaki, K., J. Schauber, A. Coda, H. Lin, R. A. Dorschner, N. M. Schechter,C. Bonnart, P. Descargues, A. Hovnanian, and R. L. Gallo. 2006. Kallikrein-mediated proteolysis regulates the antimicrobial effects of cathelicidins in skin.FASEB J. 20: 2068–2080.

48. Sørensen, O., K. Arnljots, J. B. Cowland, D. F. Bainton, and N. Borregaard. 1997. Thehuman antibacterial cathelicidin, hCAP-18, is synthesized in myelocytes and meta-myelocytes and localized to specific granules in neutrophils. Blood 90: 2796–2803.

49. Rosenfeld, Y., N. Papo, and Y. Shai. 2006. Endotoxin (lipopolysaccharide) neu-tralization by innate immunity host-defense peptides. Peptide properties andplausible modes of action. J. Biol. Chem. 281: 1636–1643.

50. Mookherjee, N., K. L. Brown, D. M. Bowdish, S. Doria, R. Falsafi, K. Hokamp,F. M. Roche, R. Mu, G. H. Doho, J. Pistolic, et al. 2006. Modulation of the TLR-mediated inflammatory response by the endogenous human host defense peptideLL-37. J. Immunol. 176: 2455–2464.

51. Iimura, M., R. L. Gallo, K. Hase, Y. Miyamoto, L. Eckmann, and M. F. Kagnoff.2005. Cathelicidin mediates innate intestinal defense against colonization withepithelial adherent bacterial pathogens. J. Immunol. 174: 4901–4907.

52. van Wetering, S., P. J. Sterk, K. F. Rabe, and P. S. Hiemstra. 1999. Defensins: keyplayers or bystanders in infection, injury, and repair in the lung? J. Allergy Clin.Immunol. 104: 1131–1138.

53. Wilson, C. L., A. J. Ouellette, D. P. Satchell, T. Ayabe, Y. S. Lopez-Boado,J. L. Stratman, S. J. Hultgren, L. M. Matrisian, and W. C. Parks. 1999. Regulationof intestinal alpha-defensin activation by the metalloproteinase matrilysin in innatehost defense. Science 286: 113–117.

54. Salzman, N. H., M. A. Underwood, and C. L. Bevins. 2007. Paneth cells, defensins,and the commensal microbiota: a hypothesis on intimate interplay at the intestinalmucosa. Semin. Immunol. 19:70–83. Epub 20May 07, 2007.

55. Schaefer, A. S., G. M. Richter, M. Nothnagel, M. L. Laine, A. Ruhling, C. Schafer,N. Cordes, B. Noack, M. Folwaczny, J. Glas, et al. 2010. A 39 UTR transition withinDEFB1 is associated with chronic and aggressive periodontitis.Genes Immun. 11: 45–54.

56. De Yang, Q. Chen, A. P. Schmidt, G. M. Anderson, J. M. Wang, J. Wooters,J. J. Oppenheim, and O. Chertov. 2000. LL-37, the neutrophil granule- and epi-thelial cell-derived cathelicidin, utilizes formyl peptide receptor-like 1 (FPRL1) asa receptor to chemoattract human peripheral blood neutrophils, monocytes, andT cells. J. Exp. Med. 192: 1069–1074.

57. Niyonsaba, F., M. Hirata, H. Ogawa, and I. Nagaoka. 2003. Epithelial cell-derivedantibacterial peptides human beta-defensins and cathelicidin: multifunctional ac-tivities on mast cells. Curr. Drug Targets Inflamm. Allergy 2: 224–231.

58. Niyonsaba, F., K. Iwabuchi, H. Matsuda, H. Ogawa, and I. Nagaoka. 2002. Epi-thelial cell-derived human beta-defensin-2 acts as a chemotaxin for mast cellsthrough a pertussis toxin-sensitive and phospholipase C-dependent pathway. Int.Immunol. 14: 421–426.

59. Chotjumlong, P., S. Khongkhunthian, S. Ongchai, V. Reutrakul, andS. Krisanaprakornkit. 2010. Human beta-defensin-3 up-regulates cyclooxygenase-2expression and prostaglandin E2 synthesis in human gingival fibroblasts. J. Peri-odontal Res. 45: 464–470.

60. Feng, Z., G. R. Dubyak, M. M. Lederman, and A. Weinberg. 2006. Cutting edge:human beta defensin 3—a novel antagonist of the HIV-1 coreceptor CXCR4. J.Immunol. 177: 782–786.

61. Ghannam, S., C. Dejou, N. Pedretti, J. P. Giot, K. Dorgham, H. Boukhaddaoui,V. Deleuze, F. X. Bernard, C. Jorgensen, H. Yssel, and J. Pene. 2011. CCL20 andb-defensin-2 induce arrest of human Th17 cells on inflamed endothelium in vitrounder flow conditions. J. Immunol. 186: 1411–1420.

62. Oppenheim, J. J., and D. Yang. 2005. Alarmins: chemotactic activators of immuneresponses. Curr. Opin. Immunol. 17: 359–365.

63. Otte, J. M., A. E. Zdebik, S. Brand, A. M. Chromik, S. Strauss, F. Schmitz,L. Steinstraesser, and W. E. Schmidt. 2009. Effects of the cathelicidin LL-37 onintestinal epithelial barrier integrity. Regul. Pept. 156: 104–117.

64. Carretero, M., M. J. Escamez, M. Garcıa, B. Duarte, A. Holguın, L. Retamosa,J. L. Jorcano, M. D. Rıo, and F. Larcher. 2008. In vitro and in vivo wound healing-promoting activities of human cathelicidin LL-37. J. Invest. Dermatol. 128: 223–236.

65. Otte, J. M., I. Werner, S. Brand, A. M. Chromik, F. Schmitz, M. Kleine, andW. E. Schmidt. 2008. Human beta defensin 2 promotes intestinal wound healing invitro. J. Cell. Biochem. 104: 2286–2297.

66. Baroni, A., G. Donnarumma, I. Paoletti, I. Longanesi-Cattani, K. Bifulco,M. A. Tufano, and M. V. Carriero. 2009. Antimicrobial human beta-defensin-2stimulates migration, proliferation and tube formation of human umbilical veinendothelial cells. Peptides 30: 267–272.

67. Canny, G., and O. Levy. 2008. Bactericidal/permeability-increasing protein (BPI)and BPI homologs at mucosal sites. Trends Immunol. 29: 541–547.

68. Canny, G., E. Cario, A. Lennartsson, U. Gullberg, C. Brennan, O. Levy, andS. P. Colgan. 2006. Functional and biochemical characterization of epithelialbactericidal/permeability-increasing protein. Am. J. Physiol. Gastrointest. LiverPhysiol. 290: G557–G567.

69. Canny, G. O., R. T. Trifonova, D. W. Kindelberger, S. P. Colgan, andR. N. Fichorova. 2006. Expression and function of bactericidal/permeability-increasing protein in human genital tract epithelial cells. J. Infect. Dis. 194: 498–502.

70. Elsbach, P., and J. Weiss. 1998. Role of the bactericidal/permeability-increasingprotein in host defence. Curr. Opin. Immunol. 10: 45–49.

71. Levy, O. 2000. A neutrophil-derived anti-infective molecule: bactericidal/perme-ability-increasing protein. Antimicrob. Agents Chemother. 44: 2925–2931.

72. Gazzano-Santoro, H., J. B. Parent, L. Grinna, A. Horwitz, T. Parsons, G. Theofan,P. Elsbach, J. Weiss, and P. J. Conlon. 1992. High-affinity binding of thebactericidal/permeability-increasing protein and a recombinant amino-terminalfragment to the lipid A region of lipopolysaccharide. Infect. Immun. 60: 4754–4761.

73. Mannion, B. A., J. Weiss, and P. Elsbach. 1990. Separation of sublethal and lethaleffects of the bactericidal/permeability increasing protein on Escherichia coli. J. Clin.Invest. 85: 853–860.

74. Levy, O., C. E. Ooi, P. Elsbach, M. E. Doerfler, R. I. Lehrer, and J. Weiss. 1995.Antibacterial proteins of granulocytes differ in interaction with endotoxin. Com-parison of bactericidal/permeability-increasing protein, p15s, and defensins. J.Immunol. 154: 5403–5410.

75. Ulevitch, R. J., and P. S. Tobias. 1999. Recognition of gram-negative bacteria andendotoxin by the innate immune system. Curr. Opin. Immunol. 11: 19–22.

76. Gazzano-Santoro, H., K. Meszaros, C. Birr, S. F. Carroll, G. Theofan,A. H. Horwitz, E. Lim, S. Aberle, H. Kasler, and J. B. Parent. 1994. Competitionbetween rBPI23, a recombinant fragment of bactericidal/permeability-increasingprotein, and lipopolysaccharide (LPS)-binding protein for binding to LPS andgram-negative bacteria. Infect. Immun. 62: 1185–1191.

77. Weiss, J., P. Elsbach, I. Olsson, and H. Odeberg. 1978. Purification and charac-terization of a potent bactericidal and membrane active protein from the granules ofhuman polymorphonuclear leukocytes. J. Biol. Chem. 253: 2664–2672.

78. Evans, T. J., A. Carpenter, D. Moyes, R. Martin, and J. Cohen. 1995. Protectiveeffects of a recombinant amino-terminal fragment of human bactericidal/permeability-increasing protein in an animal model of gram-negative sepsis. J. In-fect. Dis. 171: 153–160.

79. Lin, Y., W. J. Leach, and W. S. Ammons. 1996. Synergistic effect of a recombinantN-terminal fragment of bactericidal/permeability-increasing protein and cefa-mandole in treatment of rabbit gram-negative sepsis. Antimicrob. Agents Chemother.40: 65–69.

80. Vaishnava, S., and L. V. Hooper. 2007. Alkaline phosphatase: keeping the peace atthe gut epithelial surface. Cell Host Microbe 2: 365–367.

81. Goldberg, R. F., W. G. Austen, Jr., X. Zhang, G. Munene, G. Mostafa, S. Biswas,M. McCormack, K. R. Eberlin, J. T. Nguyen, H. S. Tatlidede, et al. 2008. In-testinal alkaline phosphatase is a gut mucosal defense factor maintained by enteralnutrition. Proc. Natl. Acad. Sci. USA 105: 3551–3556.

82. Mata-Haro, V., C. Cekic, M. Martin, P. M. Chilton, C. R. Casella, andT. C. Mitchell. 2007. The vaccine adjuvant monophosphoryl lipid A as a TRIF-biased agonist of TLR4. Science 316: 1628–1632.

83. Moyle, P. M., and I. Toth. 2008. Self-adjuvanting lipopeptide vaccines. Curr. Med.Chem. 15: 506–516.

84. Wozniak, M., J. R. Keefer, C. Saunders, and L. E. Limbird. 1997. Differentialtargeting and retention of G protein-coupled receptors in polarized epithelial cells. J.Recept. Signal Transduct. Res. 17: 373–383.

85. Lawrence, D. W., W. J. Bruyninckx, N. A. Louis, D. M. Lublin, G. L. Stahl,C. A. Parkos, and S. P. Colgan. 2003. Antiadhesive role of apical decay-acceleratingfactor (CD55) in human neutrophil transmigration across mucosal epithelia. J. Exp.Med. 198: 999–1010.

86. Louis, N. A., K. E. Hamilton, T. Kong, and S. P. Colgan. 2005. HIF-dependentinduction of apical CD55 coordinates epithelial clearance of neutrophils. FASEB J.19: 950–959.

87. Serhan, C. N. 2007. Resolution phase of inflammation: novel endogenous anti-inflammatory and proresolving lipid mediators and pathways. Annu. Rev. Immunol.25: 101–137.

88. Oh, S. F., P. S. Pillai, A. Recchiuti, R. Yang, and C. N. Serhan. 2011. Pro-resolvingactions and stereoselective biosynthesis of 18S E-series resolvins in human leukocytesand murine inflammation. J. Clin. Invest. 121: 569–581.

The Journal of Immunology 3481

by guest on July 19, 2018http://w

ww

.jimm

unol.org/D

ownloaded from