Toll-like receptor 2-mediated downstream cytokine levels as determinant of malaria pathogenesis

Background & objectives: Toll-like receptors (TLRs) are transmembrane proteins that recognize specific molecular patterns and activate downstream cytokine production usually for the eradication of invading pathogens. The objective of this study was to evaluate the genetic polymorphism of TLR2 Arg753Gln (rs 5743708) and soluble cytokines and TLR2 expression levels in malaria disease cases. Methods: The study included prospectively collected 2 ml blood samples from 153 individuals clinically suspected for malaria and confirmed by microscopy and RDT from Assam. Stratification of the study groups was done as healthy control (HC, n=150), uncomplicated malaria (UC-M, n=128) and severe malaria (SM, n=25). The PCR-restriction fragment length polymorphism (RFLP) method was applied for the analysis of TLR2 Arg753Gln polymorphism and following the ELISA for soluble serum TLR2 (sTLR2) and its associated downstream cytokines, viz. tumour necrosis factor (TNF)-? and interferon (IFN)-? levels. Results: Variation in TLR2 Arg753Gln gene showed no association with the susceptibility and the severity of malarial infection. Soluble TLR2 expression was significantly higher in uncomplicated malaria (UC-M) cases compared to healthy controls (P=0.045) and in terms of SM cases, the expression was also found to be higher in UC-M cases (P=0.078). The TNF-? expression was significantly higher in SM cases compared to both UC-M and control (P=0.003 and P=0.004). Similarly, significantly elevated expression of IFN-? was noted in SM cases compared to both UC-M (P=0.001) and healthy controls (P<0.001). Interpretation & conclusions: The present study suggests the association of deregulated TLR2 pathway that leads to the deleterious downstream immune response in the development of malarial pathogenicity.

Promoter region polymorphism & expression profile of toll like receptor-3 (TLR-3) gene in chronic hepatitis C virus (HCV) patients from India.

Background & objectives: Hepatitis C virus (HCV) induces an immune response of the host, manifested by the formation of anti-HCV antibodies mediated by adaptive and innate immunity. Toll-like receptors (TLRs) play a pivotal role in innate immunity system. This study was aimed to investigate the promoter region polymorphism and expression of TLR3 gene in patients with chronic HCV infection. Methods: Patients with chronic HCV infection (N=180) and an equal number of age-sex matched controls were included in the study. Patients positive for HCV-RNA were subjected to analysis of TLR3 polymorphism by direct sequencing of PCR products verified by comparing with the sequences reported in the National Centre for Biotechnology Information (NCBI) database (accession number: NT 022792). Expression of TLR3 gene was analyzed by semiquantitative RT-PCR using housekeeping β-actin gene as the internal control. Results: Polymorphisms at position -288G/A and -705A/G were identified. The results were significant in -705 allele (P=0.004) OR 2.79(1.46-5.42) and were associated with high risk of HCV infection. In silico sequence analysis showed the presence of ectropic viral integration site 1 encoded factor, in which G at -705 results in the loss of this site. The -7C/A polymorphism was not seen in our study cohort. The expression of TLR3 was upregulated in chronic HCV patients compared to healthy controls. Interpretation & conclusions: Polymorphism in the -705A/G allele at the promoter region of the TLR3 gene may predispose individual to HCV infection. However association of TLR3 expression with polymorphism of TLR3 promoter was not found.

Evaluation of adefovir & lamivudine in chronic hepatitis B: correlation with HBV viral kinetic, hepatic-necro inflammation & fibrosis.

Background & objectives: Chronic hepatitis B is an important cause of morbidity and mortality. We conducted a study comparing the efficacy of adefovir and lamivudine with respect to their impact on serum and hepatic viral DNA clearance, and improvement in hepatic necro-inflammatory score, in naive patients of chronic hepatitis B. Methods: This prospective randomized pilot study was conducted in Lok Nayak Hospital, New Delhi, involving 30 patients of chronic hepatitis B (both e antigen positive and negative); 15 were randomly selected to receive either adefovir or lamivudine for a period of 6 months. Quantification of serum and hepatic HBV DNA levels was done by real time PCR and liver biopsy was done at the beginning and end of 6 months. Results: Serum ALT was elevated to 2 or more times normalized in both the groups. In the adefovir group, two patients became HBeAg negative. In the lamivudine group, one patient became HBeAg negative. After therapy HBV DNA was negative in 26.7 per cent patients from adefovir group and 13.3 per cent patients from lamivudine group. Serum HBV DNA levels were correlated with the hepatic levels before therapy (r=0.843; P<0.001) and after therapy (r=0.713, P<0.001) showing strong correlation. There was a median reduction of 1.92 and 2.06 log copies per ml in serum HBV DNA load after adefovir and lamivudine therapy, respectively. The mean reduction in the histotogy activity index (HAI) score was 2 and 1.53, fibrosis score was 2.33 and 3.06 after adefovir and lamivudine therapy respectively. Interpretation & conclusions: Adefovir and lamivudine treatment caused biochemical and serological improvement when administered for about 6 months with significant reduction in HBV DNA, serum and hepatic viral load without completely clearing the virus from either serum or liver. It also helped in reduction of the necro-inflammatory and fibrosis score of patients with chronic hepatitis B. Our study also showed significant correlation between serum and hepatic HBV DNA levels both before and after therapy. There was not enough evidence to show therapeutic advantage of one drug over the other in any of the parameters measured.