The timing of death in patients with tuberculosis who die during anti-tuberculosis treatment in Andhra Pradesh, South India.

BACKGROUND: India has 2.0 million estimated tuberculosis (TB) cases per annum with an estimated 280,000 TB-related deaths per year. Understanding when in the course of TB treatment patients die is important for determining the type of intervention to be offered and crucially when this intervention should be given. The objectives of the current study were to determine in a large cohort of TB patients in India:- i) treatment outcomes including the number who died while on treatment, ii) the month of death and iii) characteristics associated with "early" death, occurring in the initial 8 weeks of treatment. METHODS: This was a retrospective study in 16 selected Designated Microscopy Centres (DMCs) in Hyderabad, Krishna and Adilabad districts of Andhra Pradesh, South India. A review was performed of treatment cards and medical records of all TB patients (adults and children) registered and placed on standardized anti-tuberculosis treatment from January 2005 to September 2009. RESULTS: There were 8,240 TB patients (5183 males) of whom 492 (6%) were known to have died during treatment. Case-fatality was higher in those previously treated (12%) and lower in those with extra-pulmonary TB (2%). There was an even distribution of deaths during anti-tuberculosis treatment, with 28% of all patients dying in the first 8 weeks of treatment. Increasing age and new as compared to recurrent TB disease were significantly associated with "early death". CONCLUSION: In this large cohort of TB patients, deaths occurred with an even frequency throughout anti-TB treatment. Reasons may relate to i) the treatment of the disease itself, raising concerns about drug adherence, quality of anti-tuberculosis drugs or the presence of undetected drug resistance and ii) co-morbidities, such as HIV/AIDS and diabetes mellitus, which are known to influence mortality. More research in this area from prospective and retrospective studies is needed.

Association of Taq I, Fok I and Apa I polymorphisms in Vitamin D Receptor (VDR) gene with leprosy.

BACKGROUND: Vitamin D Receptor (VDR) is a transacting transcription factor which mediates immunomodulatory function and plays a key role in innate and adaptive immune responses through its ligand and polymorphisms in VDR gene may affect its regulatory function. OBJECTIVE: To investigate the association of three VDR gene polymorphisms (TaqI rs731236, FokI rs2228570 and ApaI rs7975232) with leprosy. METHODS: The study group includes 404 participants of which 222 were leprosy patients (paucibacillary=87, multibacillary=135) and 182 healthy controls. Genotyping was done using PCR-RFLP technique. Statistical analysis was performed using SNP Stats and PLINK software. RESULTS: The VDR FokI (rs2228570) ff genotype, ApaI (rs7975232) AA, Aa genotype and haplotype T-f-a, T-F-A were positively associated with leprosy when compared to healthy controls. CONCLUSION: The two variants at Fok and Apa positions in VDR gene are significantly associated with leprosy. Genotypes at FokI (ff), ApaI (aa) and haplotype (T-F-a, T-f-a) may contribute to the risk of developing leprosy by altering VDR phenotype/levels subsequently modulation of immune response.

Killer cell immunoglobulin like receptor gene association with tuberculosis.

NK cells are vital components of innate immune system and are the first cells which come into picture mediating resistance against intracellular pathogens. NK cell cytotoxicity is modulated by a wide variety of cell surface receptors that recognize and respond towards infected cells. Activation of NK cells are controlled by both inhibitory and activating receptors, encoded by KIR genes and bind to HLA ligands. Not much is known about KIR genes and their influence on the pathogenesis with M. tuberculosis infection. Our study aimed at detecting the presence of 14 KIR genes, their distribution and their association with tuberculosis. Total 77 different genotype combinations were observed which belonged to B-haplotype. Fifteen genotypes were similar to those reported in other world populations while remaining 62 were unique to this study group. Inhibitory genes KIR3DL1, KIR2DL3 and activating genes KIR2DS1, KIR2DS5 conferred susceptibility towards TB either individually or in haplotype combinations. The complimentary MHC ligands need to be tested for the functional relevance of the associated genes.

Influence of Intron II microsatellite polymorphism in human toll-like receptor 2 gene in leprosy.

Leprosy is a chronic granulomatous infection caused by the obligate intracellular organism Mycobacterium leprae. TLR2 plays a key role when activated by M. leprae lipoproteins initiating protective responses which induce bacterial killing and therefore control of disease spread. Microsatellite polymorphisms in intron2 of TLR2 gene have been reported to be associated with development of clinical features of several infectious diseases. The study aims to evaluate the influence of GT microsatellite on the expression of TLR2 which could make humans prone to M. leprae infections. A total of 279 individuals were enrolled in the study, 88 were leprosy patients, 95 were house hold contacts (HHC) and 96 were healthy controls (HC). Genotyping was done using PCR-Sequencing method. TLR2 mRNA expression was analyzed by RT-PCR. IL-10 and IFN-γ levels were measured using ELISA in MLSA stimulated cell culture supernatants. Statistical analysis was performed using Chi-Square (χ(2)) test and t-tests. Allele/genotype of TLR2 microsatellite which includes longer GT repeats was associated with low TLR2 mRNA expression and high IL-10 production while that including shorter GT repeats was associated with high TLR2 mRNA expression and low IL-10 production. High IL10 producing allele of TLR2 microsatellite might predispose house hold contacts to leprosy.

IL-10 high producing genotype predisposes HIV infected individuals to TB infection.

Interleukin (IL-10), an anti-inflammatory cytokine, is known to have dual effect on the host immune system. One of these roles is that it provides an effective autoregulatory mechanism which protects the host from excessive inflammation and tissue damage which is in part initiated by the Th1 driven pro-inflammatory immune responses during infections (such as TB, HIV and malaria). However, though beneficial, this autoregulatory mechanism is at times exploited by pathogens which evade elimination by Th1 driven immune response leading to chronic infections. The main aim of this study therefore was to study the influence of IL-10 polymorphism in relation to its levels with respect to HIV-TB co-infection. A total of 452 participants were categorized into HIV (121), active tuberculosis (TB) (118), HIV-TB (HT) (106) groups and healthy control group (107). Polymorphism for IL-10 gene (positions -1082, -819, -592) was studied using ARMS-PCR, RFLP. IL-10 and IFN-γ levels in antigen stimulated cultures were measured using ELISA. Statistical analysis was performed using Chi-Square (χ(2)) test, One-way ANOVA and t-tests. IL-10 (-1082) GG genotype was positively associated with HIV-TB, whereas AG with HIV and AA with TB. The cohort with GG genotype also had significantly high stimulated levels of IL-10 compared to AG and AA. AC genotype was significantly frequent in HIV-TB group at IL-10 (-592) position when compared with controls. HIV positive individuals with GG genotype at IL-10 (-1082) position and high IL-10 levels may have a high risk of developing TB co-infection.

Vaccine for tuberculosis: up-regulation of IL-15 by Ag85A and not by ESAT-6.

IFN-γ is the most commonly measured cytokine released by the cells to define the cellular immune responses induced by the vaccine candidates for tuberculosis. IL-15 acts as a co-stimulator in IFN-γ production by NK cells and may therefore be important in the control of Mycobacterium tuberculosis that requires IFN-γ for clearance. The aim of the study is to determine whether Ag85A can also stimulate the innate immune response through the expression of IL-15, a cytokine that bridges the innate and adaptive immune systems. The expression of IL-15 was up regulated by about 4 fold in PPD+ healthy controls as compared with TB patients. Significantly higher expression of IL-15 mRNA in the Ag85A stimulated cells not only in PPD+ healthy controls but also in TB patients substantiates the use of Ag85A as a vaccine candidate over ESAT-6.

Association of TAP 1 and 2 gene polymorphisms with human immunodeficiency virus-tuberculosis co-infection.

Major histocompatibility complex (MHC) class I binding peptides are carried from cytosol to the lumen of the endoplasmic reticulum (ER) by transporter associated with antigen processing (TAP), an integral ER membrane protein composed of two subunits, TAP1 and TAP2. Polymorphism in TAP genes may influence these proteins further affecting the antigen peptide presentation, indirectly resulting in the viral escape mechanism from cell-mediated immunity in human immunodeficiency virus (HIV). Our aim was to study the influence of these polymorphism in study groups with HIV-tuberculosis (TB) (n = 110), TB (n = 105), and HIV (n = 130) compared with healthy controls (n = 183), using the tetraprimer amplification refractory mutation system (ARMS)-polymerase chain reaction method. Our results demonstrated that the GG genotype at TAP1 position 333 and GA genotype at TAP1 position 637 were positively associated with HIV-TB co-infection and these genotypes may act as a risk factor for developing TB co-infection in HIV-positive individuals.