Ejghal Rajaâ, Hida Moustapha, Bennani Mounya Lahkim, Meziane Mariame, Aurag Rabia, Lemrani Meryem
Laboratory of Parasitology and Vector-Borne-Diseases, Institut Pasteur du Maroc, Casablanca, Morocco; Laboratory of Genetic, Neuroendocrinology and Biotechnology, Faculty of Science, University Ibn Tofaïl, B.P 133, 14 000 Kénitra, Morocco.
Faculty of Medicine and Pharmacy, University Sidi Mohammed Ben Abdellah, Route de Sefrou, Fes, Morocco.
Acta Trop. 2016 Jun;158:77-82. doi: 10.1016/j.actatropica.2016.02.020. Epub 2016 Mar 2.
Visceral leishmaniasis (VL) is endemic in the Mediterranean basin and leads to the most severe form of Leishmania infection, lethal if left untreated. However, most infections are sub-clinical or asymptomatic, reflecting the influence of host genetic background on disease outcome. This study aimed to investigate possible association of TLR4 Asp299Gly, TLR4 Thr399Ile and TLR2 Arg753Gln polymorphisms with VL in Moroccan children. We enrolled 119 children with VL caused by Leishmania infantum as well as 138 unrelated children, 95 asymptomatic subjects and 43 healthy individuals who had no evidence of present or past infection. Polymorphisms were genotyped by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) and amplification refractory mutation system assay (ARMS-PCR). Results showed significant differences in genotype Thr399Ile and recessive model frequencies between VL and delayed-type hypersensitivity (DTH+) groups (p=0.018, OR=0.414CI 0.195-0.880; p=0.029, OR=0.448CI 0.214-0.938], respectively) by having the amino-acid threonine polymorphism as a reference in the VL group. Concerning the Asp299Gly there were a significant associations when comparing VL vs DTH+ (Asp299Gly genotype p=0.002, OR=0.326CI 0.158-0.671, allele frequencies p=0.033, OR=0.396CI 0.164-0.959, recessive model p=0.002, OR=0.343CI 0.172-0.681) and DTH+ vs DTH- groups (Asp299Gly genotype p=2.160E-4, OR=3.065CI 1.672-5.618, Gly299Gly genotype p=0.047, OR=0.368CI 0.299-0.452, allele frequencies p=1.406E-7, OR=29.571CI 3.907-223.8, recessive model p=4.370E-14, OR=36.965CI 8.629-158.3), by having the aspartic acid polymorphism as a reference these results suggest that the allele A (savage) confer protection against the clinical manifestations but not against the infection. Furthermore, there was a significant association regarding the Arg753Gln genotype (p=0.002, OR=0.326CI 0.158-0.671), allele frequencies (p=0.033, OR=0.396CI 0.164-0.959) and when applying a recessive model (p=0.002, OR=0.343CI 0.172-0.681) in the VL vs DTH+ groups. The same results was observed when comparing DTH+ vs DTH- groups (p=4.136E-6, OR=0.211CI 0.104-0.428), allele frequencies (p=0.008, OR=0.327CI 0.137-0.779) and recessive model (p=1.748E-5, OR=0.244CI 0.124-0.480). The results provide evidence that allele C in Thr399Ile and allele G in Arg753Gln polymorphisms may lead to protection against the clinical disease. Our data provide insights into the possible role of TLR2 and TLR4 variations in VL susceptibility.
内脏利什曼病（VL）在地中海盆地为地方性疾病，是利什曼原虫感染最严重的形式，若不治疗会致命。然而，大多数感染为亚临床或无症状感染，这反映了宿主遗传背景对疾病结局的影响。本研究旨在调查摩洛哥儿童中TLR4 Asp299Gly、TLR4 Thr399Ile和TLR2 Arg753Gln多态性与VL之间可能存在的关联。我们招募了119名由婴儿利什曼原虫引起VL的儿童，以及138名无亲缘关系的儿童，其中95名无症状受试者和43名无当前或既往感染证据的健康个体。通过聚合酶链反应-限制性片段长度多态性（PCR-RFLP）和扩增阻滞突变系统分析（ARMS-PCR）对多态性进行基因分型。结果显示，以VL组中苏氨酸氨基酸多态性为参照，VL组与迟发型超敏反应（DTH+）组之间在基因型Thr399Ile和隐性模型频率上存在显著差异（分别为p = 0.018，OR = 0.414，CI 0.195 - 0.880；p = 0.029，OR = 0.448，CI 0.214 - 0.938）。关于Asp299Gly位点，在比较VL与DTH+组时存在显著关联（Asp299Gly基因型p = 0.002，OR = 0.326，CI 0.158 - 0.671；等位基因频率p = 0.033，OR = 0.396，CI 0.164 - 0.959；隐性模型p = 0.002，OR = 0.343，CI 0.172 - 0.681），以及在比较DTH+与DTH-组时也存在显著关联（Asp299Gly基因型p = 2.160E - 4，OR = 3.065，CI 1.672 - 5.618；Gly299Gly基因型p = 0.047，OR = 0.368，CI 0.299 - 0.452；等位基因频率p = 1.406E - 7，OR = 29.571，CI 3.907 - 223.8；隐性模型p = 4.370E - 14，OR = 36.965，CI 8.629 - 158.3），以天冬氨酸多态性为参照，这些结果表明等位基因A（野生型）可预防临床表现，但不能预防感染。此外，在VL与DTH+组之间，关于Arg753Gln基因型（p = 0.002，OR = 0.326，CI 0.158 - 0.671）、等位基因频率（p = 0.033，OR = 0.396，CI 0.164 - 0.959）以及应用隐性模型（p = 0.002，OR = 0.343，CI 0.172 - 0.681）时存在显著关联。在比较DTH+与DTH-组时也观察到相同结果（p = 4.136E - 6，OR = 0.211，CI 0.104 - 0.428）、等位基因频率（p = 0.008，OR = 0.327，CI 0.137 - 0.779）和隐性模型（p = 1.748E - 5，OR = 0.244，CI 0.124 - 0.480）。结果提供了证据，表明Thr399Ile中的等位基因C和Arg753Gln多态性中的等位基因G可能对临床疾病具有保护作用。我们的数据为TLR2和TLR4变异在VL易感性中的可能作用提供了见解。
