Gene Expression Profiling Specifies Chemokine, Mitochondrial and Lipid Metabolism Signatures in Leprosy

<div><p>Herein, we performed microarray experiments in Schwann cells infected with live <i>M. leprae</i> and identified novel differentially expressed genes (DEG) in <i>M. leprae</i> infected cells. Also, we selected candidate genes associated or implicated with leprosy in genetic studies and biological experiments. Forty-seven genes were selected for validation in two independent types of samples by multiplex qPCR. First, an <i>in vitro</i> model using THP-1 cells was infected with live <i>Mycobacterium leprae</i> and <i>M. bovis</i> bacillus Calmette-Guérin (BCG). In a second situation, mRNA obtained from nerve biopsies from patients with leprosy or other peripheral neuropathies was tested. We detected DEGs that discriminate <i>M. bovis</i> BCG from <i>M. leprae</i> infection. Specific signatures of susceptible responses after <i>M. leprae</i> infection when compared to BCG lead to repression of genes, including <i>CCL2</i>, <i>CCL3</i>, <i>IL8</i> and <i>SOD2</i>. The same 47-gene set was screened in nerve biopsies, which corroborated the down-regulation of <i>CCL2</i> and <i>CCL3</i> in leprosy, but also evidenced the down-regulation of genes involved in mitochondrial metabolism, and the up-regulation of genes involved in lipid metabolism and ubiquitination. Finally, a gene expression signature from DEG was identified in patients confirmed of having leprosy. A classification tree was able to ascertain 80% of the cases as leprosy or non-leprous peripheral neuropathy based on the expression of only <i>LDLR</i> and <i>CCL4</i>. A general immune and mitochondrial hypo-responsive state occurs in response to <i>M. leprae</i> infection. Also, the most important genes and pathways have been highlighted providing new tools for early diagnosis and treatment of leprosy.</p></div

Toll-like receptor 1 N248S single-nucleotide polymorphism is associated with leprosy risk and regulates immune activation during mycobacterial infection

Conflicting findings about the association between leprosy and TLR1 variants N248S and I602S have been reported. Here, we performed case-control and family based studies, followed by replication in 2 case-control populations from Brazil, involving 3162 individuals. Results indicated an association between TLR1 248S and leprosy in the case-control study (SS genotype odds ratio [OR], 1.81; P = .004) and the family based study (z = 2.02; P = .05). This association was consistently replicated in other populations (combined OR, 1.51; P < .001), corroborating the finding that 248S is a susceptibility factor for leprosy. Additionally, we demonstrated that peripheral blood mononuclear cells (PBMCs) carrying 248S produce a lower tumor necrosis factor/interleukin-10 ratio when stimulated with Mycobacterium leprae but not with lipopolysaccharide or PAM3cysK4. The same effect was observed after infection of PBMCs with the Moreau strain of bacillus Calmette-Guerin but not after infection with other strains. Finally, molecular dynamics simulations indicated that the Toll-like receptor 1 structure containing 248S amino acid is different from the structure containing 248N. Our results suggest that TLR1 248S is associated with an increased risk for leprosy, consistent with its hypoimmune regulatory function.Fundação Oswaldo Cruz/Programa Estratégico de Apoio à Pesquisa em SaúdeFundação Oswaldo Cruz/Programa Estratégico de Apoio à Pesquisa em SaúdeInstituto Oswaldo Cruz/FIOCRUZ (internal funds)Instituto Oswaldo Cruz/FIOCRUZ (internal funds)Fundação de Amparo a Pesquisa do Estado do Rio de JaneiroFundacao do Amparo a Pesquisa do Estado do Rio de JaneiroFundacao de Amparo a Pesquisa do Estado de Sao PauloFundação de Amparo a Pesquisa do Estado de São PauloConselho Nacional de Pesquisa e Desenvolvimento TecnológicoConselho Nacional de Pesquisa e Desenvolvimento Tecnológic

Clustering of differentially expressed genes in nerve biopsies of leprosy and non-leprous patients peripheral neuropathy.

<p>The left graph displays a dendrogram representing the 1D clusterization of genes and the 2D map corresponding to the levels of standardized gene expression profiles (z-score), while the graph on the right displays the three significant clusters (pink, blue and yellow). Red dotted lines in the dendrogram (up-left) indicate weak unions, discouraged by the Bayesian clustering analysis. Values represented in the dendrogram branches correspond to log-odds of the union of corresponding branches. Gray lines in the graphs on the right indicate gene z-scores on leprosy and non-leprous samples, while black solid and dotted lines represent the mean and CI95% of the mean for all genes belonging to each cluster, respectively. Solid pink, blue and yellow lines indicate the mean of all genes in all samples belonging to the leprosy and non-leprous groups.</p

Discrimination between leprosy and non-leprous patients with peripheral neuropathy by combination of LDLR and CCL4 expression.

<p>Graph of a trained classification tree, where rounded rectangles represent internal nodes and hexagons represent terminal nodes. Percentages in each node represent the proportion of specified observations in each group.</p

Gene expression from nerve biopsies from leprosy and non-leprous patients with peripheral neuropathy.

<p>Among the 47-gene set only genes that showed at least a suggestive result (n = 15) are presented. Two-tailed levels of significance less than or equal to 0.01 (**), 0.05 (*) and 0.1 (^.) were considered as “highly significant”, “significant”, and “suggestive”, respectively. A total of 50 samples non-leprous patients (white columns) and 35 samples from leprosy samples (black columns).</p