Association of <i>IL10</i> Polymorphisms and Leprosy: A Meta-Analysis

<div><p>Leprosy is a chronic infectious disease that depends on the interplay of several factors. Single nucleotide polymorphisms (SNPs) in host immune related genes have been consistently suggested as participants in susceptibility towards disease. Interleukin-10 (IL-10) is a crucial immunomodulatory cytokine in mycobacterial pathogenesis and especially the -819C>T SNP (rs1800871) has been tested in several case-control studies indicating association with leprosy risk, although a recent consensus estimate is still missing. In this study, we evaluated the association of the -819C>T SNP and leprosy in two new Brazilian family-based populations. Then, we performed meta-analysis for this polymorphism summarizing published studies including these Brazilian family-based groups. Finally, we also retrieved published studies for other distal and proximal <i>IL10</i> polymorphisms: -3575 T>A (rs1800890), -2849 G>A (rs6703630), -2763 C>A (rs6693899), -1082 G>A (rs1800896) and -592 C>A (rs1800872). Results from meta-analysis supported a significant susceptibility association for the -819T allele, with pooled Odds Ratio of 1.22 (CI = 1.11–1.34) and <i>P</i>-value = 3x10^–5 confirming previous data. This result remained unaltered after inclusion of the Brazilian family-based groups (OR = 1.2, CI = 1.10–1.31, <i>P-</i>value = 2x10^–5). Also, meta-analysis confirmed association of -592 A allele and leprosy outcome (OR = 1.24, CI = 1.03–1.50, <i>P</i>-value = 0.02). In support of this, linkage disequilibrium analysis in 1000 genomes AFR, EUR, ASN and AMR populations pointed to r² = 1.0 between the -592C>A and -819C>T SNPs. We found no evidence of association for the other <i>IL10</i> polymorphisms analyzed for leprosy outcome. Our results reinforce the role of the -819C>T as a tag SNP (rs1800871) and its association with leprosy susceptibility.</p></div

Forest plots summarizing association of <i>IL10</i> promoter polymorphisms and leprosy.

<p><b>(A)</b> Forest plot for -592 C>A (rs1800872). Five case-control studies were evaluated under random-effects model. Bars represent 95% confidence interval and boxes represent OR values. <b>(B)</b> Forest plot for -819 C>T (rs1800871). Nine case-control studies were evaluated under random-effects model. Bars represent 95% confidence interval and boxes represent OR values.</p

Characteristics for the Brazilian family-based studies.

<p>Abbreviations: SD, standard deviation; WHO, World Health Organization.</p><p>^a Data is presented as total counts (frequency). The number of subject counts in ethnicity and WHO classification can differ from total individuals due to missing information.</p><p>Characteristics for the Brazilian family-based studies.</p

Forest plot for -819 C>T (rs1800871) including Brazilian Family-based data (MG and RJ).

<p>Bars represent 95% confidence interval and boxes represent OR values.</p

Flow diagram of the process of identification of eligible studies.

<p>Flow diagram of the process of identification of eligible studies.</p

Single nucleotide polymorphisms of cytokine-related genes and association with clinical outcome in a Chagas disease case-control study from Brazil

<div><p> BACKGROUND The severity of chronic chagasic cardiomyopathy (CCC), the most frequent clinical outcome of Chagas disease (CD), has been associated with cytokine-enriched heart tissue inflammation, and high serum levels of transforming growth factor (TGFβ), interferon-gamma (IFNγ), and tumour necrosis factor (TNF). Conversely, increased interleukin (IL)-10 serum concentrations have been associated with asymptomatic CD. Cytokines and cytokine-related gene polymorphisms may control cytokine expression and have been proposed to contribute to CCC outcomes. OBJECTIVES We evaluated the association of 13 cytokine-related genes (TGFB: rs8179181, rs8105161, rs1800469; IL10: rs1800890, rs1800871, rs1800896; IFNG: rs2430561; TNF: rs1800629; BAT1: rs3853601; LTA: rs909253, rs2239704; TNFR1: rs767455; TNFR2: rs1061624) with risk and progression of CCC. FINDINGS Four hundred and six seropositive patients from CD endemic areas in the state of Pernambuco, north-eastern Brazil, were classified as non-cardiopathic (A, 110) or cardiopathic (mild, B1, 163; severe, C, 133). We found no evidence of TGFB, IL10, TNF, or TNFR1/2 gene polymorphisms associated with CCC risk or progression. Only BAT1 rs3853601 −22G carriers (B1 vs. C: OR = 0.5; p-value = 0.03) and IFNG rs2430561 +874AT (A vs. C: OR = 0.7; p-value = 0.03; A vs. B1+C: OR = 0.8; p-value = 0.02) showed a significant association with protection from cardiopathy in a logistic regression analysis with adjustment for gender and ethnicity; however, the association disappeared after performing adjustment for multiple testing. A systematic review of TNF rs1800629 −308G>A publications included five studies for meta-analysis (534 CCC and 472 asymptomatic patients) and showed no consensus in pooled odds ratio (OR) estimates for A allele or A carriers (OR = 1.4 and 1.5; p-values = 0.14 and 0.15, respectively). In CD patients, TNF serum levels were increased, but not affected by the TNF rs1800629 −308A allele. MAIN CONCLUSIONS Our data suggest no significant contribution of the analysed gene variants of cytokine-related molecules to development/severity of Chagas' heart disease, reinforcing the idea that parasite/host interplay is critical to CD outcomes.</p></div

Genetic polymorphisms of the <i>IL6</i> and <i>NOD2</i> genes are risk factors for inflammatory reactions in leprosy

<div><p>The pathways that trigger exacerbated immune reactions in leprosy could be determined by genetic variations. Here, in a prospective approach, both genetic and non-genetic variables influencing the amount of time before the development of reactional episodes were studied using Kaplan–Meier survival curves, and the genetic effect was estimated by the Cox proportional-hazards regression model. In a sample including 447 leprosy patients, we confirmed that gender (male), and high bacillary clinical forms are risk factors for leprosy reactions. From the 15 single nucleotide polymorphisms (SNPs) at the 8 candidate genes genotyped (<i>TNF</i>/<i>LTA</i>, <i>IFNG</i>, <i>IL10</i>, <i>TLR1</i>, <i>NOD2</i>, <i>SOD2</i>, and <i>IL6)</i> we observed statistically different survival curves for rs751271 at the <i>NOD2</i> and rs2069845 at the <i>IL6</i> genes (log-rank p-values = 0.002 and 0.023, respectively), suggesting an influence on the amount of time before developing leprosy reactions. Cox models showed associations between the SNPs rs751271 at <i>NOD2</i> and rs2069845 at <i>IL6</i> with leprosy reactions (HR_GT = 0.45, p = 0.002; HR_AG = 1.88, p = 0.0008, respectively). Finally, IL-6 and IFN-γ levels were confirmed as high, while IL-10 titers were low in the sera of reactional patients. Rs751271-GT genotype-bearing individuals correlated (p = 0.05) with lower levels of IL-6 in sera samples, corroborating the genetic results. Although the experimental size may be considered a limitation of the study, the findings confirm the association of classical variables such as sex and clinical forms with leprosy, demonstrating the consistency of the results. From the results, we conclude that SNPs at the <i>NOD2</i> and <i>IL6</i> genes are associated with leprosy reactions as an outcome. <i>NOD2</i> also has a clear functional pro-inflammatory link that is coherent with the exacerbated responses observed in these patients.</p></div

Graphical abstract to illustrate a possible effect of <i>NOD2</i> rs751271 SNP in leprosy reactions.

<p>Patients with the rs751271-GT genotype had lower IL-6 levels, which could influence the inflammatory balance and the susceptibility to or protection against leprosy reactions. NS: Not statistically significant.</p

Serum dosage of IL-6, IFN-γ, and IL-10 and in leprosy patients that did not develop (No Reaction) or developed (Reaction) a reaction.

<p>(A) IL-6 dosage; No Reaction, N = 46; Reaction, N = 31. (B) IFN-γ dosage; No Reaction, N = 44; Reaction, N = 34. (C) IL-10 dosage; No Reaction, N = 41; Reaction, N = 23. The values were converted to a logarithmic scale. Cytokine production (pg/mL) was evaluated by ELISA and the median values were compared by a Mann–Whitney <i>t</i> test.</p

Clinical characteristics of leprosy patients according to leprosy reaction outcome.

<p>Clinical characteristics of leprosy patients according to leprosy reaction outcome.</p