Polymorphisms in genes TLR1, 2 and 4 are associated with differential cytokine and chemokine serum production in patients with leprosy

BACKGROUND Leprosy or hansen’s disease is a spectral disease whose clinical forms mostly depends on host’s immune and genetic factors. Different Toll-like receptors (TLR) variants have been described associated with leprosy, but with some lack of replication across different populations. OBJECTIVES To evaluate the role of polymorphisms in genes TLR1, TLR2 and TLR4 and susceptibility to leprosy in a genetic case control study; to verify the association between genotypes of these markers and the immunological profile in the serum of patients with leprosy. METHODS Pre-designed TaqMan® assays were used to genotype markers at TLR1 (rs4833095, rs5743551), TLR2 (rs7656411, rs3804099) and TLR4 (rs1927914, rs1927911). A panel of cytokines and chemokines was accessed by enzime-linked immunosorbent assay (ELISA) test in the serum of a subgroup of patients with and without leprosy reactions. FINDINGS Our results show an association between the T allele of rs3804099 at the TLR2 gene and increased risk for leprosy per se [Odds ratio (OR) = 1.296, p = 0,022]. In addition, evaluating the association between different genotypes of the TLR1, 2 and 4 markers and cytokine/chemokine serological levels, IL-17 appears as an immunological marker regulated by the polymorphism of the three TLR genes evaluated, whereas different TLR1 genotypes were associated with differential production of IL-12p40 and MCP-1(CCL2). Furthermore, other relevant serum markers such as CXCL-10 and IL-6 seemed to be regulated by TLR2 variants and IL-1β was related to TLR4 genotypes. MAIN CONCLUSIONS All together our data points that the tested TLR markers may have a regulatory role in the immunity against Mycobacterium leprae, by driving the host’s production of key cytokines and chemokines involved in the pathogenesis of this disease.

Polymorphisms in genes TLR1, 2 and 4 are associated with differential cytokine and chemokine serum production in patients with leprosy.

BACKGROUND: Leprosy or hansen's disease is a spectral disease whose clinical forms mostly depends on host's immune and genetic factors. Different Toll-like receptors (TLR) variants have been described associated with leprosy, but with some lack of replication across different populations. OBJECTIVES: To evaluate the role of polymorphisms in genes TLR1, TLR2 and TLR4 and susceptibility to leprosy in a genetic case control study; to verify the association between genotypes of these markers and the immunological profile in the serum of patients with leprosy. METHODS: Pre-designed TaqMan® assays were used to genotype markers at TLR1 (rs4833095, rs5743551), TLR2 (rs7656411, rs3804099) and TLR4 (rs1927914, rs1927911). A panel of cytokines and chemokines was accessed by enzime-linked immunosorbent assay (ELISA) test in the serum of a subgroup of patients with and without leprosy reactions. FINDINGS: Our results show an association between the T allele of rs3804099 at the TLR2 gene and increased risk for leprosy per se [Odds ratio (OR) = 1.296, p = 0,022]. In addition, evaluating the association between different genotypes of the TLR1, 2 and 4 markers and cytokine/chemokine serological levels, IL-17 appears as an immunological marker regulated by the polymorphism of the three TLR genes evaluated, whereas different TLR1 genotypes were associated with differential production of IL-12p40 and MCP-1(CCL2). Furthermore, other relevant serum markers such as CXCL-10 and IL-6 seemed to be regulated by TLR2 variants and IL-1ß was related to TLR4 genotypes. MAIN CONCLUSIONS: All together our data points that the tested TLR markers may have a regulatory role in the immunity against Mycobacterium leprae, by driving the host's production of key cytokines and chemokines involved in the pathogenesis of this disease.

The -308 bp TNF gene polymorphism influences tumor necrosis factor expression in leprosy patients in Bahia State, Brazil.

Leprosy or Hansen's disease is a debilitating chronic granulomatous disease caused by Mycobacterium leprae, with high incidence and prevalence in Brazil. The -308 bp G/A single nucleotide polymorphism (SNP rs1800629) in the tumor necrosis factor (TNF) gene promoter is a proposed risk factor for leprosy. In Brazil, Northern India, Egypt and Nepal, the common G allele was associated with leprosy. In Eastern India, Thailand and Malawi the minor A allele was the risk factor. Allele A was previously associated with high TNF. We genotyped rs1800629 in 326 leprosy cases from Bahia State, Brazil, including 72 paucibacillary (PB) and 47 multibacillary (MB) without reactions, and 69 reversal reaction (RR) and 78 erythema nodosum leprosum (ENL) with reactions. Logistic regression was used to compare patient groups with 331 healthy controls. Relative TNF mRNA was determined in peripheral blood leukocytes by QRTPCR, and serum TNF levels measured by ELISA. We found that TNF mRNA expression was higher (P=0.03) in leprosy patients compared to endemic controls, but did not differ significantly between clinical subgroups. Carriage of the minor A allele was associated (P=0.003) with low TNF mRNA across leprosy patients. Nevertheless, we found no evidence for either allele at this SNP as a risk factor for leprosy per se (OR=1.12, 95% CI 0.79-1.60, P=0.52), PB (OR=0.99, 95% CI 0.54-1.81, P=0.97), MB (OR=0.86, 95% CI 0.40-1.83, P=0.70), RR (OR=1.37, 95% CI 0.79-2.38, P=0.27) or ENL (OR=0.76, 95% CI 0.40-1.45, P=0.42) when compared to endemic controls. Further studies are required to determine whether the influence of the minor A allele on TNF mRNA levels determines response to treatment, particularly in the context of ENL reaction treatment with anti-TNF therapies and RR reactions where treatment with prednisolone is known to reduce TNF levels. Our findings contribute to understanding TNF as an important determinant of leprosy immunopathology in Brazil.

The role of ERBB2 gene polymorphisms in leprosy susceptibility.

Mycobacterium leprae infects skin and peripheral nerves causing deformities and disability. The M. leprae bacterium binds to ErbB2 on the Schwann cell surface causing demyelination and favoring spread of the bacilli and causing nerve injury. Polymorphisms at the ERBB2 gene were previously investigated as genetic risk factors for leprosy in two Brazilian populations but with inconsistent results. Herein we extend the analysis of ERBB2 variants to a third geographically distinct population in Brazil. Our results show that there is no association between the genotyped SNPs and the disease (p>0.05) in this population. A gene set or pathway analysis under the genomic region of ERBB2 will be necessary to clarify its regulation under M. leprae stimulus.