Dynamic changes in pro- and anti-inflammatory cytokine profiles and gamma interferon receptor signaling integrity correlate with tuberculosis disease activity and response to curative treatment

Association of reduced tumor necrosis factor alpha, gamma interferon, and interleukin-1beta (IL-1beta) but increased IL-10 expression with improved chest radiography in patients with pulmonary tuberculosis

Mycobacterium tuberculosis infection is a major world health issue. The early identification of patients at risk for a poor response to anti-M. tuberculosis therapy would help elucidate the key players in the anti-M. tuberculosis response. The objective of the present study was to correlate the modulation of cytokine expression (interleukin-1 [IL-1], IL-6, IL-8, IL-10, IL-12, gamma interferon [IFN-gamma], interferon-inducible protein [IP-10], and monocyte chemotactic protein 1 [MCP-1]) with the clinical response to 2 months of intensive therapy. From January to December 2007, 40 M. tuberculosis-infected patients and 40 healthy patients were recruited. After exclusion for diabetes, 32 patients and 36 controls were analyzed. The clinical responses of the M. tuberculosis-infected patients on the basis of the findings of chest radiography were compared to their plasma cytokine levels measured before and after 2 months of intensive anti-M. tuberculosis therapy and 6 months of therapy with human cytokine antibody arrays. Chest radiographs of 20 of 32 M. tuberculosis-infected patients showed improvement after 2 months of intensive therapy (early responders), while the M. tuberculosis infections in 12 of 32 of the patients resolved after a further 4 months (late responders). The levels of expression of TNF-alpha, MCP-1, IFN-gamma, and IL-1beta were decreased; and the level of IL-10 increased in early responders. After adjustment for age, gender, and the result of sputum culture for M. tuberculosis, significant differences in the levels of MCP-1 and IP-10 expression were observed between the early and the late responders after 2 months of intensive anti-M. tuberculosis therapy. Due to the interpatient variability in IP-10 levels, intrapatient monitoring of IP-10 levels may provide more insight into the M. tuberculosis responder status than comparison between patients. Plasma MCP-1 levels were normalized in patients who had resolved their M. tuberculosis infections. Further studies to evaluate the association of the modulation in MCP-1 levels with early and late responses are warranted.

Mycobacterial antigen-induced T helper type 1 (Th1) and Th2 reactivity of peripheral blood mononuclear cells from diabetic and non-diabetic tuberculosis patients and Mycobacterium bovis bacilli Calmette-Guérin (BCG)-vaccinated healthy subjects

Patients with diabetes mellitus are more susceptible to tuberculosis (TB), and the clinical conditions of diabetic TB patients deteriorate faster than non-diabetic TB patients, but the immunological basis for this phenomenon is not understood clearly. Given the role of cell-mediated immunity (CMI) in providing protection against TB, we investigated whether CMI responses in diabetic TB patients are compromised. Peripheral blood mononuclear cells (PBMC) obtained from diabetic TB patients, non-diabetic TB patients and Mycobacterium bovis bacilli Calmette-Guérin (BCG)-vaccinated healthy subjects were cultured in the presence of complex mycobacterial antigens and pools of M. tuberculosis regions of difference (RD)1, RD4, RD6 and RD10 peptides. The PBMC were assessed for antigen-induced cell proliferation and secretion of T helper 1 (Th1) [interferon (IFN)-gamma, interleukin (IL)-2, tumour necrosis factor (TNF)-beta], and Th2 (IL-4, IL-5, IL-10) cytokines as CMI parameters. All the complex mycobacterial antigens and RD1(pool) stimulated strong proliferation of PBMC of all groups, except moderate responses to RD1(pool) in healthy subjects. In response to complex mycobacterial antigens, both IFN-gamma and TNF-beta were secreted by PBMC of all groups whereas diabetic TB patients secreted IL-10 with concentrations higher than the other two groups. Furthermore, in response to RD peptides, IFN-gamma and IL-10 were secreted by PBMC of diabetic TB patients only. The analyses of data in relation to relative cytokine concentrations showed that diabetic TB patients had lower Th1 : Th2 cytokines ratios, and a higher Th2 bias. The results demonstrate a shift towards Th2 bias in diabetic TB patients which may explain, at least in part, a faster deterioration in their clinical conditions.

Positive Conversion of Tuberculin Skin Test and Performance of Interferon Release Assay to Detect Hidden Tuberculosis Infection During Anti-Tumor Necrosis Factor Agent Trial

Objectives.

To evaluate tuberculin skin tests (TST) and interferon-γ (IFN-γ) assay in the detection of latent tuberculosis (TB) infection during tumor necrosis factor (TNF) antagonist treatment in Korean patients with initial negative TST result.

Methods.

Eighty-six patients with rheumatic diseases who had received anti-TNF agents for over one year were investigated. Clinical data were obtained from medical records. All patients received followup TST, and IFN-γ assay was performed in 64.

Results.

The study population consisted of 40 rheumatoid arthritis (RA), 34 ankylosing spondylitis (AS), 9 juvenile rheumatoid arthritis (JRA), and 3 other patients. The TST converted to positive in 28 (32.6%) patients. There was no significant variation between TST conversion rate and all risk factors. Although there was no statistical significance, the odds of the TST conversion rate tended to increase with the duration of TNF antagonist administration. Nine (14.1%) of 64 patients who performed an IFN-γ assay had positive results. Among 28 TST positive conversion cases, 4 patients with AS and 1 with psoriatic arthritis had positive IFN-γ assay results, and one of them developed miliary TB. However, none of the 4 RA patients with positive IFN-γ assay showed TST conversion. There was 68.6% agreement (kappa = 0.29, p = 0.02) between TST and IFN-γ assay results.

Conclusion.

Serial TST with IFN-γ assay may be useful to identify false-negative response to cases of latent Mycobacterium tuberculosis infection and new TB infections in patients with immune mediated inflammatory diseases during longterm anti-TNF therapy, especially in areas with intermediate TB burden.

Cytokines and acute phase serum proteins as markers of inflammatory regression during the treatment of pulmonary tuberculosis

OBJECTIVE

To evaluate the pattern of pro-inflammatory cytokines, anti-inflammatory cytokines and the acute phase response (APR) as markers of the response to treatment of pulmonary tuberculosis.

METHODS

Twenty-eight patients with pulmonary tuberculosis were evaluated at three time points: pretreatment (T0), treatment month 3 (T3) and treatment month 6 (T6). Levels of interferon-gamma (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha), interleukine-10 (IL-10) and transforming growth factor-beta (TGF-beta) were determined using ELISA in the supernatant of peripheral blood mononuclear cell and monocyte culture. Levels of total protein, albumin, globulins, C-reactive protein (CRP), alpha-1-acid glycoprotein (AAG) and erythrocyte sedimentation rate (ESR) were also determined. All of these parameters were also evaluated, only once, in a group of healthy controls.

RESULTS

In relation to controls, patients presented cytokine levels and APR that were higher at T0, lower at T3 and either lower (TNF-alpha, IL-10, TGF-beta, AAG and ESR) or normal (IFN-gamma and CRP) at T6.

CONCLUSIONS

For individuals with negative smear sputum microscopy, CRP, AAG and ESR are potential markers of pulmonary tuberculosis and of the need for treatment; CRP (T0 > T3 > T6 = reference) can also be a marker of treatment response. In the patients, the Th0 profile (IFN-gamma, IL-10, TNF-alpha and TGF-beta), inducer of and protector against inflammation, predominated at T0, whereas the Th2 profile (IL-10, TNF-alpha and TGF-beta), protecting against the harmful pro-inflammatory effect of the remaining TNF-alpha, predominated at T6. The behavior of IFN-gamma (T0 > T3 > T6 = controls) suggests its use as a marker of treatment response.

Interaction of Mycobacterium tuberculosis with the host: consequences for vaccine development

Mycobacterium tuberculosis, the causative agent of tuberculosis (TB), remains a major worldwide health problem that causes more than 2 million deaths annually. In addition, an estimated 2 billion people are latently infected with M. tuberculosis. The bacterium is one of the oldest human pathogens and has evolved complex strategies for survival. Therefore, to be successful in the high endemic regions, any future TB vaccine strategy will have to be tailored in accordance with the resulting complexity of the TB infection and anti-mycobacterial immune response. In this review, we will discuss what is presently known about the interaction of M. tuberculosis with the immune system, and how this knowledge is used in new and more advanced vaccine strategies.

Dynamic changes in biomarker profiles associated with clinical and subclinical tuberculosis in a high transmission setting: a four-year follow-up study

Mycobacterium tuberculosis (MTB) is a slow growing bacterium. Therefore, the immune responses associated with resolution of infection or development of disease post-exposure may take several months to evolve. We have carried out a prospective longitudinal study in a high TB transmission setting to determine the evolution of biomarkers in a recently exposed household contact (HC = 77) and their respective sputum positive index cases (TB = 17). Mycobacterium-induced cytokines [interferon-gamma (IFN-gamma), tumour necrosis factor-alpha, interleukin-6 (IL-6) and IL-10)] were assessed in whole blood cultures and immunoglobulin G (IgG1) antibodies in plasma. When compared with non-exposed community controls (endemic controls = 59) the HC group at intake showed changes in biomarkers commensurate with recent exposure. The HC group showed significant increases in IFN-gamma between 0 and 6 months (paired t-test; P = 0.001) and IL-0 between 6 and 12 months (P = 0.001), most likely reflecting the role of these cytokines in resolution and immune recovery from infection as this HC cohort remained symptom-free for 4 years without prophylactic treatment. When the TB group post-treatment was compared with the HC group, the best discriminators (ANOVA; repeated measures) were IL-10 responses at 0 (P = 0.004) and 6 months (P = 0.001) and IgG1 at 6 (P = 0.004) and 12 months (P = 0.014) with a 3-4 fold higher responses in the TB group. Therefore, within each group, biomarkers show unique profile of responses. These studies highlighted the importance of assessing multiple biomarkers in longitudinal studies for providing better understanding of protective biomarker profiles associated with resolution of clinical and subclinical infections in TB.

Neonatal innate cytokine responses to BCG controlling T-cell development vary between populations

BACKGROUND

The protective effect of Mycobacterium bovis BCG vaccination against infection and atopy varies between populations.

OBJECTIVE

To identify differences in neonatal responses to BCG between diverse populations and study longitudinal associations with memory T-cell responses.

METHODS

Cord blood mononuclear cells were collected from Papua New Guinean (PNG) and Western Australian (WA) newborns. Toll-like receptor (TLR)-2, TLR4, and TLR9 mRNA expression and in vitro BCG-stimulated (+/-IFN-gamma priming) innate cytokine responses were compared. When PNG infants were 3 months old, PBMCs were stimulated in vitro with Mycobacterium-purified protein derivative (PPD) to determine memory T-cell responses.

RESULTS

BCG-induced IL-10 and IFN-gamma responses were significantly higher in cord blood mononuclear cells of PNG newborns, and TLR2 and TLR9 expression was significantly higher and TLR4 expression lower compared with WA newborns. High neonatal IL-10 and low IFN-gamma responses to BCG were found to promote the development of PPD-memory T(H)2 responses in infancy, whereas neonatal BCG-TNFalpha responses inhibited the development of PPD-IL 10 responses. When primed with IFN-gamma, BCG-induced TNF-alpha, IL-12p70, and in particular IFN-gamma responses were enhanced to a significantly higher extent in WA than in PNG newborns. In response to IFN-gamma priming and BCG stimulation, natural killer cells of WA newborns produced IFN-gamma, whereas natural killer cells of PNG newborns contributed only indirectly to this response.

CONCLUSION

Neonatal BCG-related innate immune responses control the differentiation of T(H) memory responses and vary between populations. This may explain differences in the effects of BCG vaccination between populations.

Differential live Mycobacterium tuberculosis-, M. bovis BCG-, recombinant ESAT6-, and culture filtrate protein 10-induced immunity in tuberculosis

The high prevalence of Mycobacterium tuberculosis makes it imperative that immune responses to evaluate could be predictive of infection. We investigated live Mycobacterium- and recombinant antigen-induced cytokine and chemokine responses in patients with active tuberculosis (TB) compared with those of healthy controls from an area where TB is endemic (ECs). M. tuberculosis-, M. bovis BCG-, ESAT6-, and culture filtrate protein 10 (CFP10)-induced responses were determined in peripheral blood mononuclear cells from patients with pulmonary TB (n = 38) and ECs (n = 39). The levels of the cytokines gamma interferon (IFN-gamma) and interleukin-10 (IL-10) and the chemokines CCL2, CCL3, and CXCL9 were measured. The levels of M. tuberculosis- and BCG-induced IFN-gamma secretion were significantly reduced (P = 0.002 and P < 0.01, respectively), while the amount of IL-10 induced by both virulent (P < 0.01) and avirulent (P = 0.002) mycobacteria was increased in patients with TB. The ESAT6-induced IFN-gamma responses were increased in the patients with TB (P = 0.013) compared with those in the EC group. When tuberculin skin test (TST)-negative (TST(-); induration, <10 mm) and TST-positive (TST(+)) donors were studied separately, both TST(-) and TST(+) individuals showed increased IFN-gamma responses to M. tuberculosis compared with the responses of the patients with TB (P = 0.037 and P = 0.006, respectively). However, only TST(+) ECs showed reduced IFN-gamma responses to ESAT6 (P = 0.008) compared with the responses of the patients with TB. The levels of M. tuberculosis-induced CCL2 (P = 0.006) and CXCL9 (P = 0.017) were greater in the patients with TB. The levels of CCL3 secretion in response to Mycobacterium and antigen stimulation were comparable between the two groups. While the levels of ESAT6-induced chemokines did not differ between the patients with TB and the ECs, the levels of CFP10-induced CCL2 (P = 0.01) and CXCL9 (P = 0.001) were increased in the patients. These data indicate differential host IFN-gamma, CXCL9, and CCL2 responses to live mycobacteria and mycobacterial antigens and have implications for the identification of potential biomarkers of infection which could be used for the diagnosis of TB.

ESAT6-induced IFNgamma and CXCL9 can differentiate severity of tuberculosis

BACKGROUND

Protective responses against Mycobacterium tuberculosis are dependent on appropriate T cell and macrophage activation. Mycobacterial antigen six kDa early secreted antigenic target (ESAT6) and culture filtrate protein 10 (CFP10) can detect M. tuberculosis specific IFNgamma responses. However, most studies have been performed in non-endemic regions and to study pulmonary tuberculosis (PTB). We have studied ESAT6 and CFP10 induced cytokine and chemokines responses in PTB and extrapulmonary (EPul) TB.

METHODOLOGY

IFNgamma, IL10, CXCL9 and CCL2 responses were determined using an ex vivo whole blood assay system in PTB (n = 30) and EPulTB patients with limited (LNTB, n = 24) or severe (SevTB, n = 22) disease, and in healthy endemic controls (ECs). Responses to bacterial LPS were also determined.

PRINCIPAL FINDINGS

ESAT6- and CFP10-induced IFNgamma was comparable between ECs and TB patients. Both ESAT6- and CFP10-induced IFNgamma secretion was greater in LNTB than PTB. ESAT6-induced CXCL9 was greater in EPulTB as compared with PTB, with an increase in SevTB as compared with LNTB. CFP10-induced CCL2 was higher in PTB than LNTB patients. LPS-stimulated CXCL9 was greatest in SevTB and LPS-induced CCL2 was increased in PTB as compared with LNTB patients. A positive correlation between ESAT6-induced IFNgamma and CXCL9 was present in all TB patients, but IFNgamma and CCL2 was only correlated in LNTB. ESAT-induced CCL2 and CXCL9 were significantly associated in LNTB while correlation in response to LPS was only present in SevTB.

CONCLUSIONS

ESAT6 induced IFNgamma and CXCL9 can differentiate between limited and severe TB infections.

Cytokine gene polymorphisms across tuberculosis clinical spectrum in Pakistani patients

BACKGROUND

Pakistan ranks 7(th) globally in terms of tuberculosis (TB) disease burden (incidence 181/100000 pop./yr; prevalence of 329/pop./yr). Reports from different populations show variable associations of TB susceptibility and severity with cytokine gene polymorphisms. Tuberculosis clinical severity is multi-factorial and cytokines play a pivotal role in the modulation of disease severity. We have recently reported that the ratio of two key cytokines (IFNgamma and IL10) show significant correlation with the severity spectrum of tuberculosis. The objective of the current study was to analyze the frequency of cytokine gene polymorphisms linked to high and low responder phenotypes (IFNgamma +874 T(hi)-->A(lo) and IL10 -1082 G(lo)-->A(hi)) in tuberculosis patients.

METHODS AND FINDINGS

STUDY GROUPS WERE STRATIFIED ACCORDING TO DISEASE SITE AS WELL AS DISEASE SEVERITY: Pulmonary N = 111 (Minimal, PMN = 19; Moderate, PMD = 63; Advance, PAD = 29); Extra-pulmonary N = 67 (Disseminated DTB = 20, Localized LTB = 47) and compared with healthy controls (TBNA = 188). Genotype analyses were carried out using amplification refractory mutation system-PCR (ARMS-PCR) and stimulated whole blood (WB) culture assay was used for assessing cytokine profiles. Our results suggest that the IFNgamma +874 TT genotype and T allele was overrepresented in PMN (p = 0.01) and PMD (p = 0.02). IFNgamma +874 TT in combination with IL10 GG(lo) genotypes showed the highest association (chi(2) = 6.66, OR = 6.06, 95% CI = 1.31-28.07, p = 0.01). IFNgamma AA(lo) on the other hand in combination with IL10 GG(lo) increased the risk of PAD (OR = 5.26; p = 0.005) and DTB (OR = 3.59; p = 0.045).

CONCLUSION

These findings are consistent with the role of IL10 in reducing collateral tissue damage and the protective role of IFNgamma in limiting disease in the lung.

In vitro levels of interleukin 10 (IL-10) and IL-12 in response to a recombinant 32-kilodalton antigen of Mycobacterium bovis BCG after treatment for tuberculosis

Cell-mediated immunity plays a major role in conferring protection against tuberculosis (TB) on an individual. It is not known whether the immune status correlates with the bacterial load or whether the immunity improves after treatment. Also, it may be important to monitor treatment by being able to discriminate between active disease and successfully treated TB. The main aim of this study was to investigate the usefulness of a recombinant 32-kDa antigen (r32-kDa Ag) of Mycobacterium bovis BCG (Ag85A-BCG) as a diagnostic marker in patients being treated for TB. Specifically, the in vitro T-cell assays and the release of interleukin-12 (IL-12) (Th1-type cytokine) and IL-10 (Th2-type cytokine) in response to the r32-kDa Ag of BCG were assayed in patients with either pulmonary (sputum positive/negative, n = 74) or extrapulmonary TB (n = 49) and healthy controls. The proliferative responses of stimulated cells at 0, 2 to 4, and 6 months of treatment increased and were highly significant (P < 0.000) compared to the responses in controls. The increase in IL-12 and decrease in IL-10 release suggest that there is cytokine expression modification during different stages of TB, and treatment seems to have an influence on the levels of these cytokines, suggesting an augmentation in the protective responses. The in vitro response to the M. bovis BCG r32-kDa Ag may be useful in monitoring treatment of TB.

Genetic association and expression studies indicate a role of toll-like receptor 8 in pulmonary tuberculosis

Despite high rates of exposure, only 5-10% of people infected with Mycobacterium tuberculosis will develop active tuberculosis (TB) disease, suggesting a significant role for genetic variation in the human immune response to this infection. Here, we studied TB association and expression of 18 genes involved in the Toll-like receptor (TLR) pathways. Initially, we genotyped 149 sequence polymorphisms in 375 pulmonary TB patients and 387 controls from Indonesia. We found that four polymorphisms in the TLR8 gene on chromosome X showed evidence of association with TB susceptibility in males, including a non-synonymous polymorphism rs3764880 (Met1Val; P = 0.007, odds ratio (OR) = 1.8, 95% c.i. = 1.2-2.7). We genotyped these four TLR8 polymorphisms in an independent collection of 1,837 pulmonary TB patients and 1,779 controls from Russia and again found evidence of association in males (for rs3764880 P = 0.03, OR = 1.2, 95% c.i. = 1.02-1.48). Combined evidence for association is P = 1.2x10(-3)-6x10(-4). In addition, a quantitative PCR analysis indicated that TLR8 transcript levels are significantly up-regulated in patients during the acute phase of disease (P = 9.36x10(-5)), relative to baseline levels following successful chemotherapy. A marked increase in TLR8 protein expression was also observed directly in differentiated macrophages upon infection with M. bovis bacille Calmette-Guérin (BCG). Taken together, our results provide evidence, for the first time, of a role for the TLR8 gene in susceptibility to pulmonary TB across different populations.

Mutual modulation between interleukin-10 and interleukin-6 induced by Rhodococcus aurantiacus infection in mice

The interaction between interleukin-10 (IL-10) and interleukin-6 (IL-6) was investigated in the inflammatory response to Rhodococcus aurantiacus (R. aurantiacus) infection, in which both cytokines act as anti-inflammatory cytokines. Compared with wild-type (WT) counterparts, IL-6 gene-deficient (IL-6(-)/(-)) mice mounted a more robust production of IL-10 and tumor necrosis factor-alpha (TNF-alpha) during the initial phase of infection. Administration of anti-IL-10 antibody resulted in all the mice dying within 3 days post-infection as well as a further elevated TNF-alpha release. In vitro challenge of the macrophages from IL-6(-)/(-) and WT mice with heat-killed R. aurantiacus also showed similar results. Addition of exogenous IL-6 depressed IL-10 and TNF-alpha production by either IL-6(-)/(-) mice or IL-6(-)/(-) mouse macrophages. Likewise, WT mouse macrophages pretreated with anti-IL-10 or anti-IL-6 antibody exhibited increased production of TNF-alpha and IL-6 or IL-10 respectively. Moreover, neutralization of both IL-10 and IL-6 induced a further increase in TNF-alpha production by WT mouse cells. Overall, we conclude that IL-10 is a key element in protecting mice against mortality, and that IL-10 and IL-6 production are negatively regulated by each other although they are additive in suppressing TNF-alpha release in R. aurantiacus-infected mouse model.

Cellular responses to MPT-51, GlcB and ESAT-6 among MDR-TB and active tuberculosis patients in Brazil

Multi-drug resistant pulmonary tuberculosis (MDR-TB) may result from either insufficiency of the host cellular immune response or mycobacterial mechanisms of resistance. Mycobacterium tuberculosis-specific CD8+ and CD4+ T lymphocytes from MDR-TB patients are poorly studied. The aim of this study was to evaluate CD4+IFN-gamma+, CD4+IL-10+, CD8(+)IFN-gamma+ and CD8+IL-10+ cell populations by flow cytometry in non-resistant TB and multi-drug resistant tuberculosis (MDR-TB) patients from mid-central Brazil after stimulation with MPT-51, GlcB and ESAT-6 recombinant antigens from M. tuberculosis in comparison to tuberculin skin test negative (TST) healthy individuals. Non-resistant TB patients present specific cellular responses (CD4 and CD8, both IFN-gamma and IL-10) to GlcB, MPT-51 and ESAT-6; while MDR-TB patients present only CD8+IFN-gamma+ responses to ESAT-6 and CD8+IL-10+ responses to GlcB and ESAT-6. The results show that MDR-TB patients present impaired specific CD4 IFN-gamma and IL-10 responses and increased/normal specific CD8 IFN-gamma and IL-10 responses. This suggests an important role for CD8 function in these patients.

Impaired gamma interferon response to Mycobacterium vaccae antigens in patients with cavitary pulmonary tuberculosis

The ability of tuberculosis patients to recognize Mycobacterium vaccae-specific antigens before starting chemotherapy and according to disease severity was analyzed. We report that the M. vaccae cell wall skeleton fraction triggers more enhanced cytokine production than the whole bacterium. Moreover, a tendency was observed for a lower gamma interferon/interleukin-10 ratio in patients with cavitary disease induced by M. vaccae antigens.

Characterization of human cellular immune responses to novel Mycobacterium tuberculosis antigens encoded by genomic regions absent in Mycobacterium bovis BCG

Comparative genomics has identified several regions of differences (RDs) between the infectious Mycobacterium tuberculosis and the vaccine strains of Mycobacterium bovis BCG. We aimed to evaluate the cellular immune responses induced by antigens encoded by genes predicted in 11 RDs. Synthetic peptides covering the sequences of RD1, RD4 to RD7, RD9 to RD13, and RD15 were tested for antigen-induced proliferation and secretion of Th1 cytokine, gamma interferon (IFN-gamma), by peripheral blood mononuclear cells (PBMC) obtained from culture-proven pulmonary tuberculosis (TB) patients and M. bovis BCG-vaccinated healthy subjects. Among the peptide pools, RD1 induced the best responses in both donor groups and in both assays. In addition, testing of TB patients' PBMC for secretion of proinflammatory cytokines (tumor necrosis factor alpha [TNF-alpha], interleukin 6 [IL-6], IL-8, and IL-1beta), Th1 cytokines (IFN-gamma, IL-2, and TNF-beta), and Th2 cytokines (IL-4, IL-5, and IL-10) showed differential effects of RD peptides in the secretion of IFN-gamma and IL-10, with high IFN-gamma/IL-10 ratios (32 to 5.0) in response to RD1, RD5, RD7, RD9, and RD10 and low IFN-gamma/IL-10 ratios (<1.0) in response to RD12, RD13, and RD15. Peptide-mixing experiments with PBMC from healthy subjects showed that secretion of large quantities of IL-10 in response to RD12 and RD13 correlated with inhibition of Th1 responses induced by RD1 peptides. In conclusion, our results suggest that M. tuberculosis RDs can be divided into two major groups--one group that activates PBMC to preferentially secrete IFN-gamma and another group that activates preferential secretion of IL-10--and that these two groups of RDs may have roles in protection against and pathogenesis of TB, respectively.

Imbalanced effector and regulatory cytokine responses may underlie mycobacterial immune restoration disease

BACKGROUND

Immune restoration disease (IRD) is an adverse consequence of antiretroviral therapy, where the restored pathogen-specific response causes immunopathology. Mycobacteria are the pathogens that most frequently provoke IRD and mycobacterial IRD is a common cause of morbidity in HIV-infected patients co-infected with mycobacteria. We hypothesised that the excessive effector immune response in mycobacterial IRD reflects impaired regulation by IL-10.

RESULTS

We studied two patients who experienced mycobacterial IRD during ART. One patient developed a second episode of IRD with distinct clinical characteristics. Findings were compared with patients 'at risk' of developing IRD who had uneventful immune recovery. Peripheral blood mononuclear cells (PBMC) from all subjects were stimulated with mycobacterial antigens in the form of purified protein derivative (PPD). Supernatants were assayed for IFNgamma and IL-10. In response to PPD, PBMC from IRD patients generated IFNgamma during the first IRD episode, whilst cells from non-IRD controls produced more IL-10.

CONCLUSION

We present preliminary data from two HIV-infected patients showing an imbalance between IFNgamma and IL-10 responses to mycobacterial antigens during mycobacterial IRD. Our findings suggest that imbalanced effector and regulatory cytokine responses should be investigated as a cause of IRD.

Peripheral blood gamma interferon release assays predict lung responses and Mycobacterium tuberculosis disease outcome in mice

Current diagnostic tests for tuberculosis (TB) are not able to distinguish active disease from latent Mycobacterium tuberculosis infection, nor are they able to quantify the risk of a latently infected person progressing to active TB. There is interest, however, in adapting antigen-specific gamma interferon (IFN-gamma) release assays (IGRAs) to predict disease outcome. In this study, we used the differential susceptibilities of inbred mouse strains to M. tuberculosis infection to evaluate the prognostic capabilities of IGRAs. Using lung and blood cultures, we determined that CBA/J, DBA/2, and C3H/HeJ mice (models of heightened risk of progression to active TB) produced less antigen-specific IFN-gamma in response to M. tuberculosis culture filtrate proteins and early secreted antigenic target-6 than the relatively resistant C57BL/6 mouse strain. Additionally, reduced IFN-gamma secretion in supernatants reflected a reduced frequency of IFN-gamma-responding cells in the lung and blood and not a specific defect in IFN-gamma secretion at the single-cell level. Importantly, detection of antigen-specific IFN-gamma from blood cultures accurately reflected lung responses, indicating that blood can be an appropriate test tissue in humans. Furthermore, reduced antigen-specific IFN-gamma production and low frequencies of IFN-gamma-responding cells from peripheral blood predicted increased risk of TB disease progression across genetically diverse TB disease-susceptible mouse strains, suggesting that similar results may occur in humans. The development of efficacious predictive diagnostic tests for humans would lead to targeted therapy prior to progression to active TB, reducing transmission, incidence, and prevalence rates while maximizing the use of public health resources.

Influence of HLA-DR2 on perforin-positive cells in pulmonary tuberculosis

Perforin is one of the key effector molecules of cytotoxic T cells and natural killer cells. The influence of HLA-DRB1 alleles on peripheral blood perforin-positive CD4, CD8, CD16 and CD 56 cells was studied by flow cytometry. HLA-DRB1 typing was done in normal healthy subjects (NHS: n = 156) and patients with pulmonary tuberculosis (PTB: n = 102) by polymerase chain reaction-based sequence-specific oligonucleotide hybridization method. We observed a significantly decreased percentage of total perforin-positive cells (per(+)) (P = 0.0004); CD8(+)/Per(+) (P = 0.0005); CD16(+)/Per(+) (P = 0.05) and CD 56(+)/Per(+) cells (P = 0.001) in HLA-DR2-positive PTB patients compared to non-DR2 patients. Subtyping of HLA-DR2-positive subjects at the allelic level revealed that the percentage of CD8(+)/Per(+) cells did not differ among DRB1*1501 and DRB1*1502 patients while a trend towards a decreased percentage of CD16(+)/Per(+) and CD 56(+)/Per(+) cells was noticed in DRB1*1501 patients compared to DRB1*1502 patients. The present study suggests that HLA-DR2 may be associated with down-regulation of perforin-positive cytotoxic lymphocytes and natural killer cells in pulmonary tuberculosis.

The role of interferon-gamma in the increased tuberculosis risk in type 2 diabetes mellitus

As patients with diabetes mellitus are at increased risk of developing tuberculosis, we hypothesized that this susceptibility to mycobacterial infection is due to a defective Th1-cytokine response. To explore this hypothesis, we examined four groups of subjects in Indonesia: 23 patients with tuberculosis, 34 patients with tuberculosis and diabetes, 32 patients with diabetes only and 36 healthy controls. Ex-vivo production of interferon (IFN)gamma, tumour necrosis factor-alpha and interleukin (IL)-1beta, 6, 10, -12 and -4 was measured following stimulation with Mycobacterium tuberculosis, Escherichia coli lipopolysaccharide and phytohaemagglutinin. Patients with active tuberculosis were found to have lower IFNgamma levels and a higher production of other pro-inflammatory cytokines and IL-4, both in the presence and absence of diabetes. Diabetes patients without tuberculosis, however, showed strongly reduced non-specific IFNgamma production, which is essential for inhibition of the initial growth of M. tuberculosis. Our data suggest that a defective non-specific immune response in diabetes may contribute to an increased susceptibility to develop tuberculosis.

Longitudinal tracking of cytokines after acute exposure to tuberculosis: association of distinct cytokine patterns with protection and disease development

Household contacts (HCs) of patients with tuberculosis (TB) are at higher risk of infection as well as the development of active disease. Longitudinal tracking of antigen-specific cytokines after acute exposure may significantly advance our understanding of the dynamic changes in cytokine patterns associated with disease establishment. To achieve this objective, we carried out a prospective cohort study with healthy HCs after exposure to TB. The patterns of cytokines (gamma interferon [IFN-gamma] and interleukin 10 [IL-10]) in response to mycobacterial antigens (culture filtrate [CF] proteins) and nonspecific mitogens (phytohemagglutinin [PHA] and lipopolysaccharide [LPS]) were assessed at 0, 6, 12, and 24 months after exposure. Seven of 109 (6.4%) HCs developed active disease. Six of the seven individuals were females, and active disease developed between 12 and 15 months after exposure in 5/20 families. The most significant findings were the exponential increases ( approximately 1,000-fold) in both the CF protein- and the PHA- or LPS-induced IFN-gamma/IL-10 ratio in healthy HCs (n = 26), which peaked at 12 months, compared to the levels in HCs who developed disease (n = 7), in whom relatively flat responses were observed during the 24-month period. Linear trends for 0 to 12 and 0 to 24 months for the CF protein-induced IFN-gamma/IL-10 ratio showed significant differences between the two groups, as determined by the use of the Mantel extension test for chi(2) analysis (odds ratio = 0.45; 95% confidence interval = 0.295 to 0.685; P = 0.0002). Our results strongly suggest that the magnitude of the IFN-gamma/IL-10 ratio at 12 months after exposure may be a critical determinant in the resolution of infection. These studies provide new insights into the cytokine responses associated with disease establishment or the resolution of infection after natural exposure to TB and have implications for TB control programs as well vaccine efficacy studies.

Systemic and local interferon-gamma production following Mycobacterium ulcerans infection

Buruli ulcer disease (BUD) is an emerging predominantly tropical disease caused by Mycobacterium ulcerans. The initial pre-ulcerative skin lesion often breaks down into an ulcer with undermined edges. Healing is common but may require considerable time, and scarring often results in functional limitations. Considerable evidence has now emerged that patients with early BUD cannot mount a sufficient protective T helper 1 (Th1) cell response to M. ulcerans, but uncertainty remains as to whether immune protection is restored over time. This study investigates the Th1 cell response of patients with various stages of BUD on mycobacterial antigens. We measured interferon (IFN)-gamma levels after ex vivo whole blood stimulation with tuberculin purified protein derivative (PPD), and compared the Th1 cell response of individuals with pre-ulcerative, ulcerative and healed BUD as well as healthy controls. Moreover, the systemic Th1 cell response was related to histopathological features in the various stages of surgically resected BUD lesions. We show that patients with ulcerative and healed BUD produce significantly higher IFN-gamma levels after mycobacterial ex vivo whole blood stimulation than healthy controls, and that patients with a granulomatous tissue response produce higher IFN-gamma levels than individuals without. We therefore suggest that the mounted Th1 cell response in ulcerative BUD patients might be related to their histopathological tissue response.

Association of polymorphisms in IL-12/IFN-gamma pathway genes with susceptibility to pulmonary tuberculosis in Indonesia

Upon infection with mycobacteria the IL-12/IFN-gamma axis plays an essential role in the activation of cell-mediated immunity required for the elimination of pathogens. Mutations in genes of the IL-12/IFN-gamma axis are known to cause extreme susceptibility to infection with environmental mycobacteria, and subtle variations in these genes may influence susceptibility to more virulent mycobacteria. We analyzed the distribution of polymorphisms in four essential genes from the IL-12/IFN-gamma axis, IL12B, IL12RB1, IFNG and IFNGR1, in 382 pulmonary tuberculosis patients and 437 healthy controls from an endemic region in Jakarta, Indonesia. The IL12RB1 gene was sequenced in a subset of individuals. Nine known single nucleotide polymorphisms (SNPs) and two new silent variations, 135G>A and 1056C>T, were detected in IL12RB1. Six functional SNPs (-2C>T, 467G>A, 641A>G, 1312C>T, 1573G>A, 1781G>A) in IL12RB1, an IL12B promoter insertion/deletion polymorphism and CA repeats in IFNG and IFNGR1 were analyzed in the cohort. The IFNGR1 allele CA(12) (p=0.004) and genotype CA(12)/CA(12) (p=0.01; OR 0.5) were associated with protection from pulmonary tuberculosis. Interestingly, IL12B promoter heterozygosity was associated with protection from tuberculosis in BCG-vaccinated individuals (p=0.03; OR=0.6). This new finding supports the role that IL-23-of which IL12B encodes a subunit--plays in generation of memory T cells.