Immunology of TB and its relevance to TB Control

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1 Immunology of TB and its relevance to TB Control W. Henry Boom, M.D. TB Research Unit Case Western Reserve University NIAID-DMID: -AI70022

2 Global TB Epidemiology 2009 < to to to to or more No Estimate per population Stop TB Department Enormous Disparities In 2009: 1/3 rd World s Population Infected 9.4 Million New Cases ( >137/ ) 50% Smear+ 1.1 Million HIV MDR/58 countries with XDR 1.7 Million Deaths (380,000HIV+)

3 Why Immunology? TST/IGRA CD4 T cells & HIV Progression from LTBI to TB Rapid vs. slow response to TB Rx Risk for relapse New TB Vaccine

4 Natural History of Mycobacterium tuberculosis infection The image cannot be displayed. Your computer may not have enough memory to open the image, or the image may have been corrupted. Restart your computer, and then open the file again. If the red x still appears, you may have to delete the image and then insert it again.

5 Many T cell subsets from TST+ respond to M. tuberculosis C D 8 T c e l l c l a s s I M H C α β - T C R M Φ c l a s s I I M H C α β - T C R C D 4 T c e l l Phos. Ag γ δ - T C R γδ T c e l l C D 1 r e s t r i c t e d T c e l l s D N α β T C R CD25+ CD4 T cell, Th17, Treg

6 Immune Evasion and M. tuberculosis 1. Lung as unique environment Alternatively activated macrophages Macrophage cell membrane Inhibitory environment for T cell priming & activation transferrin R ph > 6.3 LAMP1/2 class II MHC 2. Thrives in Macrophages class I MHC ph > 6.3 M. tuberculosis ph > 6.3 Proton-ATPase Block Phagosomal Maturation (no fusion with lysosomes; exclude Proton ATP-ase) Inactivate Bactericidal Mechanisms (O 2- / H 2 O 2 /OH - ; NO; Autophagy; Apoptosis) 3. Avoids Recognition by T cells Inhibits MHC Ag processing MΦ T interferes with T cell activation

7 M. tb cell wall: rich source of immuneregulatory molecules 50% or more of dry wt. Complex Lipids, Glycolipids Novel Type IV secretory system (ESX)

8 Examples from CWRU-TBRU s 20+ yrs. experience with TB clinical trials (Uganda, Brazil, Philippines, S. Africa) Immunology linked to TB clinical trials

9 CD4 VS. CD8 T cell responses during TB treatment Hypothesis: CD8+ T cells reflect MTB load (CD4+ T cells do not) Method: CD4+ and CD8+ T cells sorted from frozen PBMC by negative selection IFN-gamma ELISPOT with ESAT6/CFP10 peptides (15-mers, overlapping by 10) Batch testing of W0,W8,W24 PBMC (first 25 TB patients in Uganda)

10 ELISPOT assessment of IFN-γ production by CD4 + and CD8 + T cells MTB-specific antigens: synthetic peptide pools representing CFP-10 and ESAT-6 CD4 + T cells: un-fractionated or CD8+ depleted peripheral blood mononuclear cells (PBMC) utilized CD8 + T cells: PBMC depleted of CD4 + and CD56 + cells All ELISPOTs performed in batches on site in Uganda using cryopreserved specimens

11 CD8+ T cells and 2 mo. Culture Conversion

12 Combination of 2 biomarkers: cavity (host) + 2 mo. sputum culture (microbe) fail as surrogates for shortening TB Rx Phase III, randomized trial Uganda, Brazil, Philippines 386 TB pts. (- cavity/cxr) - 2 mo. sput. cult. 4 vs. 6 mo. DOT NIAID-DMID: HHSN C / NO1-AI70022

13 TBRU data- differential host marker expression in cured and relapse patients Dx M2 M * * EGF C C C GRO C - C log10(tnf-beta) * MDC C - - IL C SAP P - - C time: Dx M6 SUN time: Dx M6 TBRU CRP C C C TNFβ C C C segfr C - - log10(vegf) * * * IL C svegfr2 C - - sil-4r R - R VEGF R R R time: Dx M6 time: Dx M6 sil-2ra R - - SUN TBRU Cured Relapse C: sign. higher in cured R: sign. higher in relapse

14 New TB Vaccine? BCG as Prime Oldest vaccine in use Over 3 billion doses worldwide Massive immunization campaigns (not Neth/USA) Different schedules Efficacy remains controversial (?protect disseminated TB in newborns), nevertheless.

15 Why figure out how BCG works/fails? Just move forward! (N= 40;11/10)* Better BCG: add or eliminate gene (s) (N=8) Weak MTB: knock out gene(s) (N=2) MTB proteins in viral vector: virus (MVA, AD5/35) (N=4) MTB proteins alone: beads on a string with adjuvant (e.g. HepB, HPV) (N=11) Others (nasal BCG, M. smeg., M. vaccae, Streptomyces, DNA, polysaccharides) (N=15) *StopTB Partnership/Aeras TB Vaccine Pipeline NIAID-DMID: -AI70022

16 Clinical Trials: Where should new TB vaccines focus? INFECTION BCG I O PROGRESSIVE/PEDS. NEW VACCINE Bacterial Load BCG BCG REACTIVATION/ADULTS Innate (TST -) Adaptive (TST +) Acute Chronic NIAID-DMID: -AI70022

17 Clinical Trials Issues I Adolescent & Adult Pulm. TB drive the epidemic Prevent Adult TB = Solve Peds TB BCG: prime; new vaccine + MTB boost Golden Age 5-15 yrs: Boost Live vaccines in HIV+? Reservoir of LTBI

18 The image cannot be displayed. Your computer may not have enough memory to open the image, or the image may have been corrupted. Restart your computer, and then open the file again. If the red x still appears, you may have to delete the image and then insert it again. Clinical Trials Issues II Infants: replace BCG with rbcg +/- boost to prevent inf./1 o progression Adolescents/Adults: boost to prevent 1 o or LTBI progression In Clin. Studies: Dissem. TB in infants disappears (SATVI/Worcester) Progression of LTBI to TB: 1-2%, not 5-10% (TBRU-KCS, GC6, SATVI Adolescent Cohort) Vaccine trial sites for TB limited Incidence/prevalence poorly defined Limited lab. capacity for MTB Diagnosis TB in infants: problematic Kawempe Study GC6 SATVI/UCT/Worcester

19 Paradox MTB: strong adjuvant, TLR- 2,9,?4, NOD s, etc. Vigorous MTB-specific T (CD4, CD8, γδ, CD1-restricted) and cytokine responses 90+% MTB infections are controlled: Ghon complex/granuloma MTB immune evades and persists (LTBI) T cell responses contributing to tissue damage? Can TB vaccines overcome these paradoxes?

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21 Will MTB Strain Diversity Matter?

22 Conclusions Immune responses to MTB matter! Vaccine efficacy (BCG failure/new) Diagnose LTBI (CD4 T cell/ifn-gamma) Immune failure = progression (CD4 T cell) Response to Rx and relapse Challenges Find measures of protection/immune failure/response to Rx/relapse

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24 MTB Infection vs. Disease: Risk for Infection Contact: smear + vs - intimate vs. casual contact Persistent MTB Burden: < 10 6 (INH: no R)? CFU?MTB Virulence?Host Factors Diagnosis: TST/PPD/Tyne IFN-gamma release assay (Quantiferon or T-spot)

25 MTB Infection vs. Disease: Risk for progression 5-10% lifetime; greatest in first 1-2 years Infectious Dose MTB Virulence?latency progressing to TB?direct progression to TB Genetics?IFNGR1, IL-12R?NRAMP1, MCP-1, TNFR1, IL-10 Immune function Age (young/old) Nutrition HIV, drugs (steroids, anti-tnf, etc.) Bacterial Load Innate (TST -) 5%-I O PROGRESSIVE Acute 5%-REACTIVATION 90%-PERSISTENCE Adaptive (TST +) Chronic

26 Tuberculosis I Lung Disease: Upper Lobe, Cavitation (bacterial burden: high, surface of cavity, extra-cellular)

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