Effect of IFN-γ, IL-12 and IL-10 cytokine production and mRNA expression in tuberculosis patients with diabetes mellitus and their household contacts.

OBJECTIVE: The study was carried out to understand the influence of IFN-γ, IL-12 and IL-10 cytokine production and expression in tuberculosis patients with diabetes mellitus (TBDM) and their household contacts (HHC). METHODOLOGY: The study involved a total of 300 subjects, 50 in each category of TBDM, TBDM HHC, pulmonary tuberculosis patients (PTB), PTB HHC, DM and healthy controls (HC). TBDM, PTB and their HHC, 25 each were followed at different intervals to determine their immune responses in Ag85A stimulated culture supernatants by Enzyme Linked Immunosorbent Assay (ELISA). mRNA expression by TRIZOL method in 5 cases of each category and follow-up studies were performed. RESULTS: IFN-γ and IL-12 cytokine production markedly decreased and that of IL-10 increased after Ag85A M.tb stimulation, however anti TB treatment reconstituted the response in TBDM and PTB patients. The household contacts revealed cytokine gene expression similar to that of patients and two of them developed the disease during follow-up. CONCLUSION: Cytokine responses of the patients retained after treatment highlighting the antigen importance, hence further studies with recombinant cytokines may help in coming up with a biomarker. Analogous immune responses of household contacts with the TBDM and PTB patients may assist in recognizing the high risk individuals.

Cytokine gene variants of TNF-α and IL-10 in the propensity of type 2 diabetes in south Indian population.

Chronic inflammation plays an important role in type 2 diabetes mellitus (T2DM), a common endocrinological pro-inflammatory disorder associated with insulin resistance. The objective of the present study is to see individual and combined effect of TNF-α (rs361525, rs1800629) and IL-10 (rs1800872, rs1800896) genes on T2DM susceptibility The genotyping was carried out in 200 T2DM patients and 200 healthy controls by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) using suitable primers. The results shown that TNF-α (GA of rs361525 & rs1800629) and IL-10 (AA of rs1800872 & GA of rs1800896) genes are significantly linked with T2DM development. The presence of AA-GA genotype combination for both TNF-α and IL-10 genes were elevating the risk of T2DM. Moreover, individuals bearing haplotypes AAAA, AACA and AAAG experience the increased risk of T2DM. Furthermore, gene-gene interaction analysis shown that TNF-α (GA of rs361525 & rs1800896) gene redundantly confer 3.4-fold elevated risk for T2DM. In gene-environment interaction, GA of TNF-α -1800896, W/H ratio and TG/HDL ratio were redundantly interacted each other and increase the risk of T2DM by 67-times. In conclusion, our results reveal that there is a significant association between foresaid TNF-α, IL-10 gene promoter polymorphisms and T2DM development. To the best of our knowledge this study is the first of its kind in the literature reporting the epistatic association of TNF-α (rs1800629G/A) gene with TG/HDL ratio and W/H ratio over IL-10 gene polymorphisms for T2DM susceptibility among south Indians.

AmpliSeq Screening of Genes Encoding the C-Type Lectin Receptors and Their Signaling Components Reveals a Common Variant in MASP1 Associated with Pulmonary Tuberculosis in an Indian Population.

Tuberculosis (TB) is a multifactorial disease governed by bacterial, host and environmental factors. On the host side, growing evidence shows the crucial role that genetic variants play in the susceptibility to Mycobacterium tuberculosis (Mtb) infection. Such polymorphisms have been described in genes encoding for different cytokines and pattern recognition receptors (PRR), including numerous Toll-like receptors (TLRs). In recent years, several members of the C-type lectin receptors (CTLRs) have been identified as key PRRs in TB pathogenesis. Nevertheless, studies to date have only addressed particular genetic polymorphisms in these receptors or their related pathways in relation with TB. In the present study, we screened the main CTLR gene clusters as well as CTLR pathway-related genes for genetic variation associated with pulmonary tuberculosis (PTB). This case-control study comprised 144 newly diagnosed pulmonary TB patients and 181 healthy controls recruited at the Bhagwan Mahavir Medical Research Center (BMMRC), Hyderabad, India. A two-stage study was employed in which an explorative AmpliSeq-based screening was followed by a validation phase using iPLEX MassARRAY. Our results revealed one SNP (rs3774275) in MASP1 significantly associated with PTB in our population (joint analysis p = 0.0028). Furthermore, serum levels of MASP1 were significantly elevated in TB patients when compared to healthy controls. Moreover, in the present study we could observe an impact of increased MASP1 levels on the lectin pathway complement activity in vitro. In conclusion, our results demonstrate a significant association of MASP1 polymorphism rs3774275 and MASP1 serum levels with the development of pulmonary TB. The present work contributes to our understanding of host-Mtb interaction and reinforces the critical significance of mannose-binding lectin and the lectin-complement pathway in Mtb pathogenesis. Moreover, it proposes a MASP1 polymorphism as a potential genetic marker for TB resistance.

The N-terminal domain of Mycobacterium tuberculosis PPE17 (Rv1168c) protein plays a dominant role in inducing antibody responses in active TB patients.

The PPE (proline-proline-glutamic acid) proteins of Mycobacterium tuberculosis are characterized by a conserved N-terminal domain of approximately 180 amino acids and variable C-terminal domain. Since last decade, these proteins have gained much importance in the serodiagnosis of tuberculosis (TB) as they act as a source of antigenic variation. We have demonstrated earlier that one of the PPE proteins PPE17 (Rv1168c) induces strong B-cell and T-cell responses in active TB disease and also displays a higher antibody titer compared to immunodominant antigens such as ESAT-6, Hsp60 and PPD. However, the immunodominant domain of PPE17 (N-terminal or C-terminal) was not examined in detail. In the present study, we observed that antibody responses elicited in TB patients were directed mostly towards the N-terminal domain of PPE17 (N-PPE17). The antibody generated against N-PPE17 in TB patients did not significantly cross-react with N-terminal domains of other PPE proteins used in this study. Our data suggest that the N-terminal domain of PPE17 protein is immunodominant and could be used as a better serodiagnostic marker than the full-length PPE17 protein.

Mycobacterium tuberculosis Peptidyl-Prolyl Isomerases Are Immunogenic, Alter Cytokine Profile and Aid in Intracellular Survival.

Mycobacterium tuberculosis (M. tb) has two peptidyl-prolyl isomerases (Ppiases) PpiA and PpiB, popularly known as cyclophilin A and cyclophilin B. The role of cyclophilins in processes such as signaling, cell surface recognition, chaperoning, and heat shock response has been well-documented. We present evidence that M. tb Ppiases modulate the host immune response. ELISA results revealed significant presence of antibodies to M. tb Ppiases in patient sera as compared to sera from healthy individuals. Treatment of THP-1 cells with increasing concentrations of rPpiA, induced secretion of pro-inflammatory cytokines TNF-α and IL-6. Alternatively, treatment with rPpiB inhibited secretion of TNF-α and induced secretion of IL-10. Furthermore, heterologous expression of M. tb PpiA and PpiB in Mycobacterium smegmatis increased bacterial survival in THP-1 cells as compared to those transformed with the vector control. Our results demonstrate that M. tb Ppiases are immunogenic proteins that can possibly modulate host immune response and enhance persistence of the pathogen within the host by subverting host cell generated stresses.

Toll-like receptor 1 variations influence susceptibility and immune response to Mycobacterium tuberculosis.

BACKGROUND: Tuberculosis (TB), a disease caused by Mycobacterium tuberculosis (MTB) infection, is still a global public health problem. TB susceptibility varies greatly in infected individuals, and mycobacterial recognition by the innate immune system likely affects disease course and outcome. This research describes a single nucleotide polymorphism in the Toll-like receptor (TLR) 1 gene that functionally alters the innate immune response to MTB and is associated with TB susceptibility in India. METHODS: 206 TB patients and 239 healthy controls from Hyderabad, India were analyzed for SNPs in the TLR1 and TLR2 genes, which were subsequently correlated to TB susceptibility. To test individual responses to MTB lysates, we stimulated PBMCs from genotyped healthy German individuals, as well as HEK cells transfected with TLR1/2 variants. TNF production and NF-kB activation were assessed respectively. RESULTS: Cohort analysis associated the TLR1-248N SNP (RS4833095) with TB protection. TLR1-248N expressing PBMCs from healthy controls exhibited an increased TNF response to MTB lysates. In addition to this, functional studies using HEK cell lines transfected with TLR1-248N and stimulated with MTB showed an increased NF-kB activation. CONCLUSION: SNP TLR1-248N is associated with TB protection in an Indian population and exhibits an increased immune response to MTB lysate in vitro.