Immunology of the Lung

7/24/2019 Immunology of the Lung

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Immunology of the Lung



NEUTROPHILS and TISSUE

MACROPHAGES



Neutrophil and macrophagedefense against infection

• Diapedesis

• Ameboid motion

• Chemotaxis

•

Phagocytosis





Monocyte-macrophage system

(Reticuloendothelial system )



generalized phagocytic system speciallyabundant in most exposed areas of the

body such as1.Skin

2.Lymph nodes

3.Lungs

4.Liver

5.Spleen and bone marrow



Name of cell Location

Dust cells/Alveolar macrophages pulmonary alveolus of lungs

Histiocytes connective tissue

Kupffer cells liver

Microglia neural tissue

Epithelioid cells granulomas

Osteoclasts bone

Sinusoidal lining cells spleen

Giant cells Connective Tissue

http://en.wikipedia.org/wiki/Dust_cell

http://en.wikipedia.org/wiki/Pulmonary_alveolus

http://en.wikipedia.org/wiki/Lungs

http://en.wikipedia.org/wiki/Histiocytes

http://en.wikipedia.org/wiki/Connective_tissue

http://en.wikipedia.org/wiki/Kupffer_cell

http://en.wikipedia.org/wiki/Liver

http://en.wikipedia.org/wiki/Microglia

http://en.wikipedia.org/wiki/Neural_tissue

http://en.wikipedia.org/wiki/Epithelioid

http://en.wikipedia.org/wiki/Granulomas

http://en.wikipedia.org/wiki/Osteoclasts

http://en.wikipedia.org/wiki/Bone

http://en.wikipedia.org/wiki/Sinusoidal

http://en.wikipedia.org/wiki/Spleen

http://en.wikipedia.org/wiki/Giant_cell

http://en.wikipedia.org/wiki/Connective_Tissue

http://en.wikipedia.org/wiki/Connective_Tissue

http://en.wikipedia.org/wiki/Giant_cell

http://en.wikipedia.org/wiki/Spleen

http://en.wikipedia.org/wiki/Sinusoidal

http://en.wikipedia.org/wiki/Bone

http://en.wikipedia.org/wiki/Osteoclasts

http://en.wikipedia.org/wiki/Granulomas

http://en.wikipedia.org/wiki/Epithelioid

http://en.wikipedia.org/wiki/Neural_tissue

http://en.wikipedia.org/wiki/Microglia

http://en.wikipedia.org/wiki/Liver




http://en.wikipedia.org/wiki/Connective_tissue

http://en.wikipedia.org/wiki/Histiocytes

http://en.wikipedia.org/wiki/Lungs

http://en.wikipedia.org/wiki/Pulmonary_alveolus

http://en.wikipedia.org/wiki/Dust_cell





Disease Entity Type of the immune

reaction

Major Features

Asthma I type IgE mediated

Drug-induced lung

diseases & reactions

Cytotoxic type II

CMI

The drug is a hapten

Ab or sens. Ly

Hypersensitive

pneumonitis

ABPA

Type III immune

complexes & CMI

Type I & Type III

Exposure to exogenous

allergen

Lung Tuberculosis CMI

SarcoidosisCMI Granulomatous

inflammation

Autoimmune-Mediated

Diseases

Immune Complexes

type III

Multiple pathogenesis

Pulmonary Vasculitis

Syndromes

Autoimmune,

type II & type III

Different lung

involvement

AntiphospholipidSyndrome

ACA & other types APL- antibodies

Rare are diagnosed at time

Idiopathic Pulmonary

Fibrosis

Unknown etiology Primary or end - stage

of the inflammation in

the lung

Pulmonary EosinophilicSyndromes

Elevated Eo in blood andin situ Eo>1500/mm3 Pulmonary infiltrates9 clinical forms 2



Respiratory AllergiesHypersensitivity



Hypersensitivity

Hypersensitivity refers to undesirable

reactions produced by the normal

immune system, including allergies and

autoimmunity

These reactions may be damaging,

uncomfortable, or occasionally fatal.



Classification

Type I – Immediate, Atopic,

Anaphylactic

Type II – Antibody DependentType III – Immune Complex

Type IV – Cell Mediated / Delayed

Type Of Hypersensitivity



TYPE I. Immediate OR Anaphylactic

Hypersensitivity

Type I hypersensitivity is also known as

immediate or anaphylactic hypersensitivity.

The reaction may involve skin (urticaria andeczema), eyes (conjunctivitis), nasopharynx

(rhinorrhea, rhinitis), bronchopulmonary

tissues (asthma) and gastrointestinal tract(gastroenteritis).

http://www.mondofacto.com/facts/dictionary?query=anaphylaxis&action=Search+OMD

http://www.mondofacto.com/facts/dictionary?query=urticaria

http://www.mondofacto.com/facts/dictionary?query=rhinorrhea&action=look+it+up

http://www.mondofacto.com/facts/dictionary?query=rhinorrhea&action=look+it+up

http://www.mondofacto.com/facts/dictionary?query=urticaria

http://www.mondofacto.com/facts/dictionary?query=anaphylaxis&action=Search+OMD



Mediated by IgE antibody to specific

antigens

The primary cellular component in this

hypersensitivity is the mast cell or basophil.

The reaction is amplified and/or modified

by platelets, neutrophils and eosinophils.

Mast cells stimulated and release histamine.



Most of the IgE in the body is bound withhigh affinity receptors (Fc epsilonRI), found

on mast cells and basophils.

The cells are activated by cross-linking of

Fc epsilonRI receptors via antigen binding

to the bound IgE molecules.





Such cross-linking leads to rapid

degranulation of the mast cells and therelease of primary inflammatorymediators stored in the granules.

Mast cell activation via Fc epsilonRI alsoleads to the production of two other typesof mediators. These secondary

mediators.



Molecules SOME SPACES Effects

Primary mediators

Histamine Vascular permeability,

sm contraction

Serotonin vascular permeability,

sm contraction

Secondary mediators

Leukotrienes vascular permeability,

sm contraction

Prostaglandins

vasodilation, sm

contraction, platelet

activation

Bradykinin vascular permeability,

sm contraction





Type II Hypersensitivity

The second class of damaging reactions iscaused by specific antibody binding to cellsor tissue antigens.

The antibodies are of the IgM or IgG classes

and cause cell destruction.It involves binding of antibodies (IgG or IgM)

to cell surface antigen or extracellularmatrix molecules.

Antibody directed to cell surface antigenscan activate complement to damage thecells.



Red Blood cell

with Ag on cell

membrane

IgG binds to Ag on

membraneMembrane attack

complex of

compliment lysis red

cell (cell death)



The result may be complement mediated

lysis as occurs in

Haemolytic Anemia

ABO Transfusion Reactions.

Pencillin allergy also belong to this class.



Type III (Immune-Complex Mediated)

Hypersensitivity

Due to the formation of antigen-antibody

complexes, also called immune-complexes.

Type III hypersensitivity is mediated byimmune complexes essentially of IgGantibodies.

When antibody combines with specific

antigen, immune complexes are formed.Normally they are promptly removed by

reticulo-endothelial system.



Occasionally, they persist and deposit in

tissues resulting in disorders.

In persistent microbial or viral infections,

immune complexes may be deposited in

organs eg. Kidneys - resulting in dysfunction,

in joints – arthirits, in BV – Vasculitis.

Wherever the immune complexes are

deposited, they cause inflammation and

tissue injury.





Type IV Hypersensitivity

This is the only class of hypersensitivereactions to be triggered by antigen -specific

T lymphocyte cells (not antibodies).

Cell mediated hypersensivity is inducedmainly in skin.When skin again comes in contact with

those agents, the sensitized person develops

erythema, itching, eczema or necrosis within12 – 48 hours.



The Langerhans cell in the epidermisinteracts with CD4 T cells to cause contact

sensitivity.

It occurs after sensitisation with simplechemicals, (e.g nickel & formaldehyde), plant

materials (Ivy poison, Oak poison), topically

applied drugs (sulfonamides & neomycin),some cosmetics and soaps.





(a) In the sensitization phase after initialcontact with antigen (e.g., peptides derived

from intracellular bacteria), TH cells

proliferate and differentiate into TH1 cells.Cytokines secreted by these T cells are

indicated by the dark blue balls.





(b) In the effector phase after subsequentexposure of sensitized TH1 cells to antigen,

the TH1 cells secrete a variety of cytokines

and chemokines. These factors attract and

activate macrophages and other nonspecific

inflammatory cells. Activated macrophages

are more effective in presenting antigen, thus

perpetuating the DTH response, andfunction as the primary effector cells in this

reaction.





A prolonged DTH response can lead toformation of a granuloma, a nodule-like

mass. Lytic enzymes released from

activated macrophages in a granuloma cancause extensive tissue damage.



ExamplesTuberculin response

Allergic contact dermatitis

Graft rejection

Corticosteroids and other immunosuppressive

agents are used in treatment.

Comparison of Different Types of hypersensitivity



Comparison of Different Types of hypersensitivity

characteris

tics

type-I

anaphylactic

type-II

(cytotoxic)

type-III

(immune

complex)

type-IV

(delayed type)

antibody IgE IgG, IgM IgG, IgM None

antigen exogenous cell surface soluble tissues & organs

response

time15-30 minutes minutes-hours 3-8 hours 48-72 hours

histologybasophils and

eosinophil

antibody and

complement

complement and

neutrophils

monocytes and

lymphocytes

transferred

with antibody antibody antibody T-cells

examplesallergic asthma,

hay fever

erythroblastosis

fetalis,

Goodpasture's

nephritis

SLE, farmer's lung

disease

tuberculin test,

poison ivy,

granuloma



Respiratory Allergies

(Allergic Asthma)



Asthma

Asthma is a condition characterized by

reversible bronchospasm and chronic

inflammation of airway passages.



Individuals with asthma appear to producelarge amounts of the Antibody IgE that

attach to the mast cells present in many

tissues.Exposure to a trigger such as pollen

will result in the allergen-binding mast cell-

bound IgE, which in turn causes the releaseof inflammatory mediators such as

Histamine and Leukotrienes.



The response of a patient with asthma to

these triggers can be divided into an

―early phase‖ and a ―late phase.‖



Early Phase of Asthma

The early phase of asthma is characterized by:a. Marked constriction of bronchial airways

(bronchospasm)

b. Difficulty in breathing

c. Production of excess mucus.

The bronchospasm that occurs may be the result of

the increased release of certain inflammatory

mediators such as histamine, prostaglandins andbradykinin that, in the early stages of asthmatic

response, promote bronchoconstriction rather

than inflammation.



Allerg

en

Antigen-

presenting

cell

Processed

allergen

Plasma Cells IgE antibodies

E l L t



Early

Phase

Late

Phase

Allergen

IgE antibodies Inflammation

Complications

Cellular

Infiltration

Glands

NervesBlood

vessels

Sneezing

Itching

Rhinorrhea

Congestion

Mediator

release Eosinophils

Basophils

Monocytes

Lymphocytes

Mast

cell

Irreversible

Disease?Priming

Hyper-

responsiveness

Late-phase

reaction



Late Phase of Asthma

The late phase of asthma can occur several hours after theinitial onset of symptoms and manifests mainly as an

inflammatory response.

The primary mediators of inflammation during the

asthmatic response are the white blood cells Eosinophils that stimulate mast cell degranulation and release

substances that attract other white cells to the area.

Subsequent infiltration of the airway tissues with white

blood cells such as Neutrophils and lymphocytes alsocontributes to the overall inflammatory response of the

late phase of asthma.



Some Potential Asthma Triggers..

Allergens — Pollen, pet dander, fungi, dust

mites

Perfumes

Pollutants

Cigarette smoke

Respiratory tract infections



Sign and Symptoms

Early Phase:

Shortness of breath

Cough

Chest tightness and pain

Wheezing

Cyanosis



Late Phase:

Mucosal odema

Severe bronchoconstrictionEpithelial damage



M. Tuberculosis

and

immune responses



Outline : TB history

TB epidemiology M TB bacteriology

TB clinical features

- symptoms and signs

- transmission- active vs. latent TB

Experimental models

Immune response against TB

- Innate immune defense- Adaptive immune defense

HIV and TB

Difficulties and advantages in TB research

Risk factors












Experimental models



HIV and TB

Difficulties and advantages in TB reaserch

Risk factors







The pathogen structure:












Experimental models



HIV and TB


Risk factors



M. Tuberculosis Characteristics

Slow-growing

Facultative Intracellular

Gram-positive

Non Spore Forming

Aerobic

Acid-fast bacilli



O l








Experimental models



HIV and TB


Risk factors





Spine TB :

Nemhotep,Priest of Amun died about 1000 BCE



Brain TB :



TB Meningitis :

Meningitis TB

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&docid=OSRbSc2HZUrLoM&tbnid=2TmQ-WxKnbm5MM:&ved=0CAUQjRw&url=http://ilper.wordpress.com/2012/05/18/meningitis-tuberkulosa/&ei=FTBtUueBA8qdjAKGnoGwBw&bvm=bv.55123115,d.cGE&psig=AFQjCNFdK3HIeCPGJ0iWV-p2oPgODyWn2g&ust=1382973627113013

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O li








Experimental models



HIV and TB


Risk factors





O tli








Experimental models



HIV and TB


Risk factors











Outline :








Experimental models



HIV and TB


Risk factors

Active vs. latent



Active vs. latent

TB :



Active TB :



Active TB:

Two Forms :1. Primary-progressive TB (more common

in children) :Progress rapidly to active disease

2. Post-primary TB: present after an interval of

many years following exposure



Differences :

I. Clinical presentations

II. Different temporal pathogenesis

III. Host genetic susceptibilities





Latent TB :

L TB



Latent TB :

Most infected individuals areasymptomatic

5 – 10% of latent individuals will develop

active TB during their lifetime individuals who are immunosuppressed,

particularly those with HIV coinfection

are in Higher risk

Outline :








Experimental models



HIV and TB


Risk factors



R d i f i f i



Route and site of infection

Mycobacterium tuberculosis is an obligatory aerobic,intracellular pathogen, which has a predilection forthe lung tissue rich in oxygen supply.

The tubercle bacilli enter the body via the respiratoryroute.

The bacilli spread from the site of initial infection inthe lung through the lymphatics or blood to otherparts of the body,the apex of the lung and theregional lymph node being favoured sites.

Extrapulmonary TB of the pleura, lymphatics, bone,

genito-urinary system,meninges, peritoneum, or skinoccurs in about 15 percent of TB patients.

E f ll i f b illi



Events following entry of bacilli

Stage1: Phagocytosis of M.Tb by Alveolar macrophage

Destruction of M.Tb,but some evade destruction& continue to multiply inside them & infect

Bystander macrophagesStage 2:

Influx of PMN’s,recruitment ofMonocytes,differentiate into Macrophage,but fail

to eliminate completely Logarithmic growth of bacilli,little tissue

destruction



Stage 3: Ag specific T-cells are recruited to the site

that activate monocytoid cells &

differentiate into two types of Giant cells EPITHELIOID,LANGHANS’ GIANT

CELL

Walling off infection from rest of the body& prevent dissemination of bacilli.



Stage 4: Stage of Latency (Granuloma) disrupts

under conditions of failing immune

surveillance & leads to ENDOGENOUSRE ACTIVATION of dormant foci

Characterised by CASEATION

NECROSIS



Binding of M. tuberculosis to



g f

monocytes /macrophages

Complement receptors (CR1, CR2,CR3 and CR4), mannosereceptors (MR) and other cell surface receptor molecules play animportant role in binding of the organisms to the phagocytes.

The interaction between MR on phagocytic cells andmycobacteria seems to be mediated through the mycobacterial

surface glycoprotein lipoarabinomannan (LAM). Prostaglandin E2 (PGE2) and interleukin (IL)-4, a Th2-type

cytokine,upregulate CR and MR receptor expression and function

interferon-g (IFN-g) decreases the receptor expression, resultingin diminished ability of the mycobacteria to adhere to

macrophages. There is also a role for surfactant protein receptors, CD14

receptor7 and the scavenger receptors in mediating bacterialbinding.



BA

Ph l f i



Phagolysosome fusion

Phagocytosed microorganisms are subject todegradation by intralysosomal acidic hydrolases uponphagolysosome fusion.

This highly regulated event constitutes a significantantimicrobial mechanism of phagocytes.

Prevention of phagolysosomal fusion is a mechanism bywhich M. tuberculosis survives inside macrophages.

mycobacterial sulphatides,derivatives of multiacylatedtrehalose 2-sulphate,have the ability to inhibit

phagolysosomal fusion. studies demonstrated that M. tuberculosis generates

copious amounts of ammonia in cultures,which isthought to be responsible for the inhibitory Effect.

F t f lf d M Tb



Fate of engulfed M.Tb

Anti mycobacterial effector functionsROI

RNI

Other mechanisms (IFN-γ ,TNF-α)MACROPHAGE APOPTOSIS

FIG

MACROPHAGE ACTIVATION



MACROPHAGE ACTIVATION

IFN ,TNF (Th1 cells) Most welldocumented

Vitamin D

SLC11A1 (formerly Nramp1)

Reacti e o e i te ediates (ROI)



Reactive oxygen intermediates (ROI)

Hydrogen peroxide (H2O2), one of the ROIgenerated by macrophages via the oxidative burst,was the first identified effector molecule thatmediated mycobactericidal effects of mononuclearphagocytes.

M.tuberculosis infection induces the accumulation ofmacrophages in the lung and also H2O2 production.

Similar local immune response in tuberculous asciticfluid has also been demonstrated.

Increased production of hydrogen peroxide by

alveolar macrophages is not specific for TB. Moreover, the alveolar macrophages produced less

H2O2 than the corresponding blood monocytes

Reactive nitrogen intermediates (RNI)



Reactive nitrogen intermediates (RNI)

Phagocytes upon activation by IFN andTNF generate NO & related RNI via

iNOS2

1,25 dihydroxy Vit D3 reported to inducethe expression of NOS2

High level expression of NOS 2 detected

immunohistochemically in macrophagesobtained by BAL in individuals with active

PTB



Other mechanisms of growth



g

inhibition/killing

IFN and TNF mediated antimycobacterialeffects

VIT D3 alone or in combination with IFN

and TNF able to activate macrophage toinhibit/kill M.Tb

Macrophage apoptosis



Macrophage apoptosis

potential mechanism involved in macrophage defenseagainst M. tuberculosis is apoptosis or programmedcell death.

apoptosis associated with TB is mediated through a

downregulation of bcl-2, an inhibitor of apoptosis Within the granuloma, apoptosis is prominent in the

epithelioid cells as demonstrated by condensedchromatin viewed by light microscopy or with the in

situ terminal transferase mediated nick end labeling(TUNEL)

Results in reduced viability of M.Tb

Evasion of host immune response by



p

M.tuberculosis Modulation of antigen presentation to avoid elimination

by T cells. Protein secreted by m. Tuberculosis such as superoxide

dismutase and catalase are antagonistic to ROI.

Mycobacterial components such as sulphatides, LAM andPHENOLIC- GLYCOLIPID I (PGLI) are potent oxygen

radical scavengers. M.Tuberculosis-infected macrophages appear to be

diminished in their ability to present antigens toCD4+T cells, which leads to persistent infection.

Another mechanism by which antigen presenting cells(APCS) contribute to defective T cell proliferation andfunction is by the production of cytokines, including TGF-Β,IL-10 OR IL-6.

Virulent mycobacteria were able to escape from fusedphagosomes and multiply

Host immune mechanisms in



TB

Innate immune response Acquired immune response

Humoral

Cell mediatedCD 8

CD 4

Th1

Th2

Immune response in TB :



Immune response in TB :

1. Formation of Granulomas2. Initials events

3. MQ apoptosis

4. Role of PMN(Neu)

Formation of



Granulomas







The classical feature of human TBgranulomas:

The presence of a necrotic caseous corethat is thought to be secondary to cell lysis

that results in a central hypoxic

environment .

Caseation necrosis :



Caseation necrosis :

Granuloma in active & latent TB :



Granuloma in active & latent TB :

In latent TB the bacilli reside in thecentral hypoxic zone in a metabolically

altered state

In active TB they can replicate inperipheral oxygenated areas.

Are they purely protective for the

host or do they promote infection? The pathogen may be able to

engineer a supportive environment

in the granuloma

Granuloma classification in active



TB:

1. The classical caseous granuloma :central eosinophilic debris surrounded bymacrophages and a layer of lymphocytes

2. The non-necrotizing granuloma:internal core of macrophages and someneutrophils surrounded by a lymphocytelayer

3. The suppurative granuloma: centralcore of degenerative neutrophils

surrounded by macrophages andmultinucleated giant cells and an outerenvelope of lymphocytes

First line of defence



First line of defence

Influx of phagocytic cells including :1. primarily resident alveolar MQ

2. recruited neutrophils and DCs

Escape : TB prevents phagolysosomal fusionand persist in the phagosome

Immune defense: Opsonization of the bacilli

prior to infection inhibits this blockade ofphagolysosomal fusion

Role of MQ :



Role of MQ :

Infection of MQ with M.TB can induce:1. necrotic death: allows exit from MQ

and therefore cell-to-cell spread of the

bacilli

2. Apoptotic death : is associated with

diminished pathogen viability andenhanced immunity

Efferocytosis



Efferocytosis

TB – infected MQ are themselves rapidlyengulfed by uninfected MQ through a

process called efferocytosis , generally

regarded as a constitutive housekeepingfunction of macrophages.



The type of cell death is regulated by :



The lipid mediators include :

1. (proapoptotics): eicosanoids , prostaglandin E2(PGE2)

2. (pronecrotic): lipoxin A4 (LXA4)

Virulent strains of TB evade innate defensemechanisms of the host by inducing LXA4 andinhibiting PGE2 production

They lead to MQ necrosis and inhibition of MQapoptosis, ultimately resulting in mycobacterialspread.

Role of Neutrophils



Role of Neutrophils Lung Neu facilitate activation of naive antigen-specificCD4+

Tcells during M .TB infection. IT promote an anti – M.TB adaptive immune response by

delivering the bacilli to DCs in a form that makes DCsmore effective initiators of CD4+ T cell activation.

Neu have a protective or detrimental effect during animmune response to TB infection may be determined by:

1. The genetics of the pathogen as well as by the genetics ofthe host

2. The stage of TB disease3. Tissue environment

4. Network of cytokines

Detrimental role of Neu :



Detrimental role of Neu :

Neutrophils are dominant producers of IL-10

in the lung .

Depletion of neutrophils reduces the lung

bacterial load while enhancing IL-6 and IL-17,

but not IFN-γ, responses



Outline :



TB history





Experimental models

Immune response against TB- Innate immune defense

- Adaptive immune defense

HIV and TB


Risk factors

Innate immune response



Innate immune response

The phagocytosis and the subsequent secretion of IL-12 are processes initiated in the absence of priorexposure to the antigen and form a component ofinnate immunity.

The other components of innate immunity arenatural resistance associated macrophageprotein (Nramp),neutrophils, natural killercells (NK) .

PLASMA LYSOZYME and other enzymes may playan important role in the first line defense, of innateimmunity to M. tuberculosis.

The role of CD-1 restricted CD8+ T cells andnon-MHC restricted T cells(γ/δ cell) have beenimplicated but incompletely understood.

Nramp



Nramp

Nramp(SLC11A1) is crucial intransporting nitrite from intracellularcompartments such as the cytosol to moreacidic environments like phagolysosome,where it can be converted to NO.

Integral membrane protein,ion transporterfamily esp Feᶧᶧ

Defects in Nramp production increasesusceptibility to mycobacteria.

NRAMP1 gene might not be associated withthe susceptibility to pulmonary and spinal TBin the Indian population

NEUTROPHILS



NEUTROPHILS

Increased accumulation of neutrophil in the granuloma and

increased chemotaxis has suggested a role for neutrophils. At the site of multiplication of bacilli, neutrophils are the

first cells to arrive followed by NK cells, γ/δ cells andα/β cells.

There is evidence to show that granulocytemacrophage-

colony stimulating factor (GM-CSF) enhances phagocytosis ofbacteria by neutrophils

Human studies have demonstrated that neutrophils provideagents such as defensins, which is lacking for macrophage-mediated killing.

neutrophils can bring about killing of M. tuberculosis in thepresence of calcium under in vivo conditions.

NK CELL Effector cells of innate immunity.

Directly lyse the pathogens or can lyse infected



Directly lyse the pathogens or can lyse infected

monocytes.

Culture with live m. Tuberculosis brought about theexpansion of NK cells

During early infection, NK cells are capable of activating

phagocytic cells at the site of infection.

A significant reduction in nk activity is associated withmultidrug resistant tb (MDR-TB).

Nk activity in BAL has revealed that different types of

pulmonary tb are accompanied by varying degrees of

depression Apoptosis is a likely mechanism of NK cytotoxicity. NK

cells produce IFN-g and can lyse mycobacterium pulsed

target cells.

Lowered NK activity during TB infection is probably the

TOLL LIKE RECEPTOR



TOLL LIKE RECEPTOR

Phylogenetically conserved mediators ofinnate immunity essential for microbialrecognition on macrophages & dendriticcells

M. tuberculosis can immunologically activatecells via either TLR2 or TLR4 in a CD 14-independent, ligand-specific manner

TLR 2 – LAM

TLR 4 – Heat labile factor

TLR 9 – cpg DINUCLEOTIDES



TLR binds to target Coupling of IRAK -1 signalling molecules

& MyD88 (myeloid differentiation) gene

Translocation of NF κB (transcriptionfactor) from cytosol to nucleus

Cytokine production

Innate immune factors :



1. TNF2. Inflammation

3. Pattern recognition receptors ,Adaptor

proteins

TNF



Role :

1. Formation and maintenance of the integrity ofthe granuloma

2. Boosting the intracellular killing of bacilli

Granuloma formation could occur even in theabsence of TNF signaling, but these granulomaswere :

Delayed More necrotic

With higher bacillary numbers.

Inflammation :



1. Eicosanoids

2. Matrix metalloproteinases :

MMP-1 and MMP-9 : key collagenase upregulated

in patients with TB and associated with increasedlung pathology in transgenic mice

3. Vitamin D

a pro-hormone that in kidney converts to itsactive form .Conversion can also occur in

granulomatous tissue.

V D3 h l d fl



Vit D3 has regulatory and anti-inflammatory

immune effects ,therefore continues to be ofpotential therapeutic interest.

Historically ,sunlight exposure and vitamin D

were used as treatments for TB.

Pattern recognition receptors

d Ad t t i



and Adaptor proteins :

Pattern-recognition receptors (PRRs):

1. Toll-like receptors (TLRs)

2. C-type lectin receptors (CLRs)includingdectin-1, mannose receptor, and DC-SIGN

3. Nod-like receptors (NLRs)

MyD88 and CARD9 :



MyD88 and CARD9 :

- master adaptors of TLR

- critical for protective immunity to M.TB in

mouse models

TLR2, TLR4, and TLR9 play a role in host

recognition of M.TB

Outline :



TB history





Experimental models



HIV and TB


Risk factors

Acquired immune response



q p

Humoral immune response: Since M. tuberculosis is an intracellular

pathogen, the serum components may notget access and may not play any

protective role. Although many researchers have

dismissed a role for B cells or antibody in

protection against TB, recent studiessuggest that these may contribute to theresponse to TB.

Adaptive immune response :



p p

1. T cells2. DC cells

3. CD-1 restricted response

4. B cell5. Cytokines

DC cell



DCs in lymph nodes from patients with M.TB may themselvescontain M.TB

Depletion of CD11c+ cells in mice before intravenous infection

with M.TB delays the development of CD4+ T cell responses

T cells



The most important T cells is CD4+ T cells

CD8+ T cells also contribute to anti-TBimmunity by:

1. Secreting IFNγ To Activate MQ to ControlInfection2. Secreting products that can directly kill The

TB bacilli.

However, CD8+ T cells clearly can notcompensate for a lack of CD4+ T cells.



Cellular immune response



p

T CELLS M.TB is a classic example of pathogen

with a protective response relying on CMI

Activated T cells migrate to site ofinfection and interact with APC’s.

Tuberculous Granulomas contain both

CD4 & CD 8 T cells & helps to containthe infection within Granuloma and

prevent reactivation.

CD4 T CELLS



Most important cells in protectiveresponse against M.Tb

Primary effector function - production of

IFN γ & other cytokines to activateMacrophage

Also related to NOS2 expression

Other unknown functions(protective)which are IFN & NOS2 independent

Target for vaccine design

CD 8 T CELLS



Play in regulating Th1/Th2 balance Studies: TB with slow regression was

associated with an ↑ CD 8 T cell in BAL F

Capable of secreting IFN & IL 4 (Mφ

activation) Lysis of infected human dendritic cells & Mφ

By CD8 T cells specific for M.Tb Ag reducesintracellular bacterial numbers(CTL)

o Killing : Perforin/Granulysin pathway

Attractive vaccine candidate

T cell APOPTOSIS



Attenuation of CMI by inducing T CELLapoptosis in M.Tb

Leads to diminished M.Tb stimulated IFNγ

& IL 2 production TB infection leads to CD 95 mediated

Th1 depletion

Non classically restricted CD 8 T

cell



cell

CD 1 restricted T cells (NK T cells)γ/δ T cells

T reg CELLS

γ/δ T cells



Large granular lymphocytes with dendriticmorphology in lymphoid tissue

Non MHC restricted

Function as cytotoxic T cells formonocytes pulsed with mycobacterial

antigen.

Secrete cytokines involved in granulomaformation.

NK T CELLS



CD 1 molecules are antigen presentingmolecules that present lipids or

glycolipids to T cells.

Usually found on dendritic cells present inthe lungs.

Stimulate CD 1 restricted T(NK T cells)

in the granuloma that can have abystander effect on infected Mφ.

T reg cells



T cells with suppressing (other T cells) capability

CD4 cells expressing CD 25 FOXp3,transcription factor essential for development of T

reg cells (also MARKER)

CTLA4 expressed on T reg induce negative signalling(contact dependent CD80/CD86))

It secrete IL 10,TGF β which supress activated T cells It requires

Expansion & recruitment(CCR1,CCR4) at pathologic sites forthe above actions

Express TLR2,TLR 4 On its surface

TLR2 engagement –ELIMINATION → Th1 response TLR 4 engagement – EXPANSION →immunosuppression

Th1/Th2 dichotomy



Th1 secrete IL2, IFNγ

Protective role in intracellular infections. Th2 secrete IL4, IL5, IL10.

Exert a negative influence on the immune response

IL 12 induce Th1 type responseTh1 type response relate directly to the clinical

manifestations of the disease

Limited TB: alveolar lymphocytosis with high levels ofIFNγ.

Far advanced / cavitary disease : no Th1 response.

Proinflammatory Cytokines TNF Alfa (Stimulation of monocytes, macrophages, and dendritic cells withm c bacteria r m c bacterial r d cts ind ces the r d cti n f TNF a



mycobacteria or mycobacterial products induces the production of TNF-, aprototype proinflammatory cytokine)

TNFα plays a key role in granuloma formation, induces macrophageactivation, and has immunoregulatory properties.

In tuberculosis patients, TNF- production is present at the site ofdisease.

Systemic spill over of TNF- may account for unwanted

inflammatory effects like fever and wasting. (double edged sword)

Clinical deterioration early in treatment is associated with aselective increase of TNFα in plasma , and quick recovery isassociated with a rapid decrease of TNFα in plasma .

To limit the deleterious effects of TNF α, systemic production ofTNF- is downregulated and soluble TNF- receptors which blockTNF- activity are increased .

In line with this, the use of potent monoclonal anti-TNF-antibodies in Crohn’s disease and rheumatoid arthritis has been

associated with increased reactivation of tuberculosis (including

IL-1β



produced by monocytes, macrophages,and dendritic cells .

In tuberculosis patients, IL-1β is

expressed in Excess and at the site ofdisease.

Acute phase response

Fever & cachexia

IL-6



IL-6, which has both pro- and anti-inflammatory properties , is produced earlyduring mycobacterial infection and at the siteof infection.

Role :inflammation,hematpoeisis,differentiation ofT cells

IL-6 may be harmful in mycobacterial

infections, as it inhibits the production ofTNF- and IL-1.

IL 12



IL-12 is a key player in host defense against M. tuberculosis.

IL-12 is produced mainly by phagocytic cells(Mφ,DC) IL-12 has a crucial role in the induction of IFN-γ

production.

In tuberculosis, IL-12 has been detected in lung infiltrates, in

pleurisy, in granulomas , and in lymphadenitis. The expression of IL-12 receptors is also increased at the site

of disease.

In humans suffering from recurrent nontuberculousmycobacterial infections, deleterious genetic mutations in the

genes encoding IL-12p and IL-12R have been identified.Thesepatients display a reduced capacity to produce IFN- γ.

IL-12 is a regulatory cytokine which connects the innate andadaptive host response to mycobacteria and which exerts itsprotective effects mainly through the induction of IFN-γ

IL-18 and IL-15



IL-18, a novel proinflammatory cytokine which shares many

features with IL-1, was initially discovered as an IFN--inducing factor, synergistic with IL-12.

IL-18 also stimulates the production of otherproinflammatory cytokines, chemokines, and transcriptionfactors .

Also, M. tuberculosis-mediated production of IL-18 byperipheral blood mononuclear cells is reduced intuberculosis patients, and this reduction may be responsiblefor reduced IFN-γ production .

IL-15 resembles IL-2 in its biologic activities, stimulating T-cell and NK-cell proliferation and activation .

Unlike IL-2, however, IL-15 is primarily synthesized bymonocytes and macrophages

IL 2



Pivotal in generating immune response Induce expansion of pool of lymphocytes

Secreted by CD4 Th1 subtype

lymphocytes Influence the course of Tuberculosis

IFNγ



The protective role of IFN- in tuberculosis is well

established, primarily in the context of antigen-specific T-cell immunity.

Produced by both CD4,CD8 T cells & NK cells

Augment antigen presentation leading to recruitmentof Lymphocytes

potent activator of infected macrophage resulting inlytic mechanisms

can be used as a surrogate marker of infection with M. tuberculosis

Ability of cells to respond to this cytokine is morepredictive than the amount.

Severely depressed in far advanced cases of TB

Anti-Inflammatory Cytokines



The proinflammatory response which isinitiated by M. tuberculosis is antagonized

by anti-inflammatory mechanisms

IL-4, IL-10, and transforming growthfactor beta (TGF β)

IL 10



Produced by Mφ after phagocytosis ofM.Tb

Downregulation of IFN γ,TNFα ,IL 12

Macrophage deactivation Directly inhibits CD4 T cell by inhibiting

APC function of M.Tb infected cells

M.Tb induced IL 10 suppresses aneffective immune response

TGF β



Produced by monocytes and dendriticcells after stimulation with M.Tb or LAM

Inhibits IFN γ production andproliferation

In Mφ,it antagonises antigenpresentation,proinflammatory cytokineproduction & cellular activation

Involved in TISSSUE DAMAGE & FIBROSISby promoting macrophage collagenasesand deposition of collagen matrix

IL 4



Deleterious effects of IL 4 in intracellularinfections including TB ascribed tosuppression of IFN γ & macrophageactivation

Progressive disease & reactivation were asso

with an ↑ IL 4 Overexpression of IL 4 intensified tissue

damage

Conversely,Inhibition of IL 4 didn’t seem to

promote cellular immunity So, IL 4 in TB is subject of controversy !



CD1-Restricted Responses



TB contains glycolipid Ag that arepresented by The CD1 family molecules

Glycolipid-reactive T cells play a role in an

effective response to TB

They proliferate and produce IFN-γ in

response to TB glycolipids

B cells



Follicle-like B cell have been observed inthe lungs of M.TB patients and in the

granulomas of infected mice

Role :

1. moderate inflammatory progression

2. modulating immune activation andsusceptibility to infection by induction of

IL-10

IFNγ



The most invariably detected cytokine atthe sites of human TB infection in :

- Lung (most )

- bronchoalveolar lavage (BAL) fluid- pleuritis fluid

- lymph nodes

IFN-γ-Mediated Killing

in MQ :



IFN-γ-

inducible molecules include: iNOS , LRG-47, an IFN inducible GTP-

binding protein

IFN-γ is also important for endosome

maturation and the induction of

antimicrobial peptide



Control of Inflammation and CD4+

T Cells



various mechanisms are in place to preventimmunopathology, including:

1. Foxp3+ regulatory T cells

2. IL-103. PD1 ( expressed by T cells from TB patients)

PD-L1 is overly abundant in the whole blood of

active TB patients



PD1 binded to PDl1---> negative signal

chronic infection

PD1 deletion ---- > increase of M.TB-specificCD4+ T cell --- > active TB

This finding demonstrated the importance of afinely regulated immune response to control

disease.

IL-17 :



Both IFN-γ and IL-17-producing T cells areinduced during mycobacterial infection

IFN-γ serves to limit the IL-17-producing T cell

population IL-17 can also be produced by γδ T cells and a

non-CD4+ CD8+ population .

Role :- Granuloma formation

- Th1 enhancement

FOLLOWING BCG VACCINATION WITH AMYCOBACTERIAL PEPTIDE:



IL-17 is required for theaccelerated recruitment of

IFN-γ-producing cells to

the lung as a result ofincreased concentrations of

the chemokines CXCL9, 10,

and 11, which recruit cells

to sites of inflammation

IL 23



Essential for the IL-17 response during TB

Dispensable for protection and antigen-

specific IFN-γ responses if IL-12p70 is

available

The double-edged sword ofsuppressive

cytokines in tuberculosis



cytokines in tuberculosis

IL10

TH2 cytokine

Type1 IFN

IL10



An immunosuppressive cytokine induced by TB

for immune evasion

If overproduced, IL-10 can contribute to

chronic infection

IL-10 was elevated in the lungs , BAL fluid ,

sputum and serum of active TB patients

Activation of TLR4 (but not of TLR2) will



induce higher levels of IL-10 production by

MQ

Bone marrow – derived Neu infected in vitro or

Neu isolated from the lungs of mice challenged

with TB produce significant levels of IL-10

Th2 Cytokines



Chronic worm infection of mice reducesimmunogenicity to M.TB and reduce Th1

responses.

Generally ,Helminthes reduce protective

immune responses to M.TB infection.

Type I IFNs



The type I IFN family of cytokines havepleiotropic effects on the broader immuneresponse

Role :

1. Increases susceptibility to M.TB 2. Suppresses production of host-protective

cytokines including IL-1 and IL-12 followingM.TB infection in MQ

3. Induction of the immunosuppressivecytokine IL-10




y

TB epidemiology

M TB bacteriology



- transmission

- active vs. latent TB

Experimental models



HIV and TB


Risk factors

HIV and TB :



TB is the most common opportunisticinfection worldwide in HIV-1-infectedpersons

Antiretroviral therapy (ART) for HIV-1infection improves immune resistance to TB

Vitamin D reportedly inhibits HIV-1 and TBinfection in MQ through the induction ofautophagy.



TB-IRIS



HIV+ patient ---> immunosuppressed--->ART

----> decreased viral load and increased

CD4+ T cells ---> sudden over activation of

immune system ----> rapid recognition of

pathogens in body (like TB ) ----> causes

severe systemic inflammatory disease

Outline : M TB history



y

M TB epidemiology

M TB bacteriology

TB clinical feature

- symptoms

- transmission


Experimental models



HIV and TB


Risk factors



Outline : M TB history



M TB epidemiology

M TB bacteriology

TB clinical feature

- symptoms

- transmission


Experimental models



HIV and TB

Difficulties and advantages in studying

Risk factors



























Epidemiology of Interstitial Lung

Diseases



Idiopathic pulmonary fibrosis

Occupational/environmental

Post inflammatory pulmonary fibrosis Sarcoidosis

Connective tissue disease

Hypersensitivity pneumonitis Drugs and radiation

3

Pulmonary Immunobiology and InflammationConsensus 2000

“adopted” pathways of immune control in processing



foreign antigens

mucociliary clearance

1010 particles per day

5x108 alveoli / 100m2 area upper & lower respiratory

tracts - ciliated epithelium

lymphatic tissues - NALT,

BALT, draining lymph nodes secretory IgA - immobilizes Ag

AM - poor APC, but “excellentcleaners” without initiating aninflammation - preventing thealveolar capil. membrane

T-cells - residual T - cells

CD4 - /CD8 - T cells

CD4+ & CD8+ - hyporesponsive

B- cells - high % in interstitium

4


pulmonary inflammatory events



Neutrophils - under normal conditions the lung is designed toexclude Neu from alveolar capillary membrane;

- transendothelium trafficking via CAM

- phagocytic defence - ingesting and clearing damaged epithelium

Eos, Ba, Mast cells – transvessels migration, role in Asthma,

Eosinophilic Pneumonia, Lung Fibrosis, Lung parasitic diseases

Oxidative stress - reactive oxygen and NO intermediates

tissue injury; antioxidants - glutathione (100x) higher than in other

tissues, extracellular superoxide dismutase (alveolar type II cells)

5


unique immune characteristics



type II alveolar cells – secreting and dividing cells

(Surfactant, SOD3, IL-8, MCP-1, MIP12, RANTES)

bronchiolar epithelial serous cells (Clara cells) - secretingand dividing cells (stem cells for ciliated/not ciliated bronch. epith.)

(lactoferrin, - defensin, cathelicidins, SP, cyt-p450)

type II alveolar cells and Clara cells - a potent source ofcytokines and variety peptide/protein antibiotics - LL37/ hCAP18,PhosphoLipase - A2, Clara Cell 26kDa protein

unique immune characteristics

6

Immunologic Methods for Diagnosisin Lung Diseases



blood ( serology ) – C3, C4, C1-IHN, Ig (G, A, M), IgE, CRP, 1-AT, autoantibodies, infections diseases

blood ( cells ) - CMI - CD3, CD4, CD8, CD19, NK, adhesion

molecules CD62L, CD11b, CD54, CD25, CD86

cutaneous tests – test for type 1 allergic reaction; MULTITEST®

CMI (Skin Test Antigens for Cell-Mediated Immunity); Mantu test

invasive methods - bronchoscopy, pleural punction - respiratory cells

profile in BALF and PF biopsy - histological examination, immunohistochemial staining

7

parameter blood % BALF %

BALF normal respiratory cells profile



Ma 77 - 87

Lymphocytes 28 - 39 7 - 14.7

Neutrophils 1.2 - 2.8

Eosinophils 0.2 - 0.4

CD3 78 3 74 1.5

CD4 42 3 44 2.5

CD8 36

2.3 31

3.5

CD4+/CD25+ 7 1.6 4.3 0.3

CD19 11 - 16 <5

NK 10 - 19 6 - 8

Тh/Тs 0.9 - 1.5 1.1 - 1.7 8

Pleural Fluid normal respiratory cells profile



parameter Nonsmokers % Smokers %

Ma 64 - 80 69 - 81

lymphocytes 18 - 36 12 - 28

neutrophils 0 - 1 1 - 2

eosinophils 0 0

Mesotelial cells 0 - 2 0 -2

Тh/Тs 0.75 (0.6 - 1) 0.72 (0.4 - 1.4)

9

Autoimmune - Mediated Lung Disease

Connective tissue disease SLE RA SS PSS DM



Connective tissue disease - SLE, RA, SS, PSS, DM

Antiphospholipid Syndrome (APS)

Pulmonary Vasculitis Syndromes

systemic necrotizing vasculitis ( Polyarteritis Nodosa, Allergic

granulomatosis of Churg & Strauss )Wegener’s Granulomatosis, Henoch-Schonlein Purpura,

Behcet’s Disease

Goodpasture’s Syndrome - pulmonary-renal involvement

Post inflammatory Pulmonary Fibrosis

31

Connective Tissue Diseases

clinical features – polyserositis

SLE - pleuritis 30%; chest pain 50%; atypical pneumonia - lupus



pneumonitis - 71%; pulmonary hypertension.; DAH;

pneumothorax, hemothorax, vasculitis

RA - interstitial lupus pneumonitis

PSS - dyspnea, chr. cough, pleuritis, fibrosis, pulm. hypertension

immunologic diagnosis - serology immunologic diagnosis - cytology – BALF, PF

Neu - 41%, Eos - 24%

with clinical picture - worse baseline fibrosis

Ly - 24% asymptomatic

in 56% of the cases- BALF cytology is the once way for the right

diagnosis and for monitoring the treatment response

32

Autoimmune - Mediated Lung Disease in conclusion



serology - autoantibodies immunologic diagnosis - BALF - hemorrhagic alveolitis - over

80% of the cells are activated, peripheral blood neutrophils

immunofluorescence - linear or granular deposition of immune

complexes along glomerular / alveolar basement membrane, pulmonary arteries, veins

treatment - immune suppression (corticosteroid,

cyclophosphamide), plasmapheresis

37

References



Demedts M et al. Eur Respir J Suppl.2001, 32, 2-16.

Crapo JD et al. Am J Respir Crit Care Med, 2000, 162 (5), 1983-6.

Statement on Sarcoidosis. Am J Respir Crit Care Med, 1999, 160, 2, 736-755.

Statement on Sarcoidosis. Am Fam Physician, 2001, 15, 6, 553-556.

Andreeva H. et al. Allergy & Asthma, 6, 2001, 25-30.

Israel-Assayag E et al. Am J Respir Crit Care Med, 1999, 159,1830- 34. Mittoo S et al. Respir Med, 2009, 103 (8): 1152-8.

Meltzer EB&Noble PW. Orph J Rare Dis, 2008, 26, 3-8.

Marchand E&Cordier J-F. Orph J Rare Dis, 2006, 1, 1-11.

BAL Cooperative Group. Am Rev Respir Dis, 1990, 141:169.

50

REFERENCES



TUBERCULOSIS–

WILLIAMROM,STUART GARAY

TUBERCULOSIS – SURENDRA

SHARMA,ALLADIMOHAN

IMMUNOLOGY OF TUBERCULOSIS-

IJMRDr.ALAMELA RAJU,TRC,CHENNAI

IMMUNOLOGY OF TUBERCULOSIS:

FROM BENCH TO BEDSIDE

Reference :



Immunology of the Lung

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