Wound healing genes and susceptibility to cutaneous leishmaniasis in Brazil

Abstract

Leishmania braziliensis causes cutaneous (CL) and mucosal (ML) leishmaniasis. In the mouse, Fli1 was identified as a gene influencing enhanced wound healing and resistance to CL caused by L. major. Polymorphism at FLI1 is associated with CL caused by L. braziliensis in humans, with an inverse association observed for ML disease. Here we extend the analysis to look at other wound healing genes, including CTGF, TGFB1, TGFBR1/2, SMADS 2/3/4/7 and FLII, all functionally linked along with FLI1 in the TGF beta pathway. Haplotype tagging single nucleotide polymorphisms (tag-SNPs) were genotyped using Taqman technology in 325 nuclear families (652 CL cases; 126 ML cases) from Brazil. Robust case-pseudocontrol (CPC) conditional logistic regression analysis showed associations between CL and SNPs at CTGF (SNP rs6918698; CC genotype; OR 1.67; 95%CI 1.10–2.54; P=0.016), TGFBR2 (rs1962859; OR 1.50; 95%CI 1.12–1.99; P=0.005), SMAD2 (rs1792658; OR 1.57; 95%CI 1.04–2.38; P=0.03), SMAD7 (rs4464148; AA genotype; OR 2.80; 95%CI 1.00–7.87; P=0.05) and FLII (rs2071242; OR 1.60; 95%CI 1.14–2.24; P=0.005), and between ML and SNPs at SMAD3 (rs1465841; OR 2.15; 95%CI 1.13–4.07; P=0.018) and SMAD7 (rs2337107; TT genotype; OR 3.70; 95%CI 1.27–10.7; P=0.016). Stepwise logistic regression analysis showed that all SNPs associated with CL at FLI1, CTGF, TGFBR2, and FLII showed independent effects from each other, but SNPs at SMAD2 and SMAD7 did not add independent effects to SNPs from other genes. These results suggest that TGFβ signalling via SMAD2 is important in directing events that contribute to CL, whereas signalling via SMAD3 is important in ML. Both are modulated by the inhibitory SMAD7 that acts upstream of SMAD2 and SMAD3 in this signalling pathway. Along with the published FLI1 association, these data further contribute to the hypothesis that wound healing processes are important determinants of pathology associated with cutaneous forms of leishmaniasis.

Wound healing genes and susceptibility to cutaneous leishmaniasis in Brazil: Role of COL1A1

“…The COL1A1 FBAT analysis for the ML clinical phenotype, and leishmaniasis per se (CL+ML disease) in the primary (Families 101–168), replication (Families 169–325) and combined data set are presented in Supplementary Tables 1 and 2, respectively. Of interest, a trend for association (nominal P =0.079) between rs2586488 and ML disease in the replication families (Supplementary Table 1) showed the minor allele as the risk allele, whereas for CL disease (Table 1) the major allele was the risk allele, reminiscent of earlier findings with other wound healing genes (Castellucci et al, 2012; Castellucci et al, 2011). This contributed to reduction in the strength of associations seen at both rs1061237 and rs2586488 in the analysis of CL+ML as leishmaniasis per se (Supplementary Table 2).…”

“…Sample collections made during two different time periods, 2000–2004 and 2008–2010, were well-matched geographically (Castellucci et al, 2012) and demographically (Table 1). Table 2 provides details of SNPs genotyped, and demonstrates that all SNPs were at a MAF ≥0.25 in this Brazilian population.…”

“…The infection is associated with a broad spectrum of clinical phenotypes, resulting from both environmental risk factors and a combination of the host’s immune and genetic background. In the last few years we have shown that polymorphisms at genes associated with wound healing and tissue repair are important risk factors for cutaneous leishmaniasis (CL) caused by Leishmania braziliensis (Castellucci et al, 2012; Castellucci et al, 2011). Thus, the FLI1 gene, initially identified and mapped as a gene controlling susceptibility to CL caused by L. major infection in mice (Sakthianandeswaren et al, 2010; Sakthianandeswaren et al, 2005), was also associated with development of CL in humans exposed to L. braziliensis in Brazil.…”

Fine mapping under linkage peaks for symptomatic or asymptomatic outcomes of Leishmania infantum infection in Brazil

“…Further functional studies will be required to determine the possible role of LTBP4 in contributing to TGF-β regulation of VL pathogenesis. Our findings are also consistent with our prior reports of association between cutaneous leishmaniasis and genes in, or affecting, the TGF-β pathway (Castellucci et al, 2012; Castellucci et al, 2011), lending support to the broader importance of this pathway in pathogenesis of leishmaniasis.…”

Host genetics and parasitic infections

“…FL1 is a transcription factor that represses CTGF (encoding connective tissue growth factor) expression via transforming growth factor-b signalling, thereby affecting collagen synthesis. Polymorphisms at loci involved in this pathway have been investigated, and significant results have been obtained for associations with CL at FL1, CTGF, TGFBR2, SMAD2, and SMAD7, and for associations with ML at SMAD3 and SMAD6 [44].…”