Laboratory of Human Molecular Genetics, Department of Genetics, Federal University of Paraná, Curitiba, Brazil.
Laboratory of Molecular Immunopathology, Department of Clinical Pathology, Clinical Hospital, Federal University of Paraná, Curitiba, Brazil.
PLoS Negl Trop Dis. 2018 Aug 9;12(8):e0006705. doi: 10.1371/journal.pntd.0006705. eCollection 2018 Aug.
Pathophysiological mechanisms are still incompletely understood for leprosy, an urgent public health issue in Brazil. Complement receptor 1 (CR1) binds complement fragments C3b/C4b deposited on mycobacteria, mediating its entrance in macrophages. We investigated CR1 polymorphisms, gene expression and soluble CR1 levels in a case-control study with Brazilian leprosy patients, aiming to understand the role of this receptor in differential susceptibility to the disease.
Nine polymorphisms were haplotyped by multiplex PCR-SSP in 213 leprosy patients (47% multibacillary) and 297 controls. mRNA levels were measured by qPCR and sCR1 by ELISA, in up to 80 samples.
Individuals with the most common recombinant haplotype harboring rs3849266T in intron 21 and rs3737002T in exon 26 (encoding p.1408Met of the York Yka+ antigen), presented twice higher susceptibility to leprosy (OR = 2.43, p = 0.017). Paucibacillary patients with these variants presented lower sCR1 levels, thus reducing the anti-inflammatory response (p = 0.040 and p = 0.046, respectively). Furthermore, the most ancient haplotype increased susceptibility to the multibacillary clinical form (OR = 3.04, p = 0.01) and presented the intronic rs12034383*G allele, which was associated with higher gene expression (p = 0.043), probably increasing internalization of the parasite. Furthermore, there was an inverse correlation between the levels of sCR1 and mannose-binding lectin (initiator molecule of the lectin pathway of complement, recognized by CR1) (R = -0.52, p = 0.007).
The results lead us to suggest a regulatory role for CR1 polymorphisms on mRNA and sCR1 levels, with haplotype-specific effects increasing susceptibility to leprosy, probably by enhancing parasite phagocytosis and inflammation.
麻风病是巴西亟待解决的公共卫生问题，但其发病机制仍不完全清楚。补体受体 1（CR1）可结合沉积在分枝杆菌上的补体片段 C3b/C4b，介导其进入巨噬细胞。我们通过巴西麻风病患者的病例对照研究，检测了 CR1 多态性、基因表达和可溶性 CR1 水平，旨在了解该受体在疾病易感性差异中的作用。
采用多重 PCR-SSP 对 213 例麻风病患者（47%为多菌型）和 297 例对照者的 9 个多态性进行单体型分析。通过 qPCR 测量 mRNA 水平，通过 ELISA 测量 sCR1，共分析了 80 个样本。
携带 21 号内含子 rs3849266T 和 26 号外显子 rs3737002T（编码 York Yka+抗原的 p.1408Met）的最常见重组单体型的个体，麻风病易感性增加了两倍（OR=2.43，p=0.017）。携带这些变异体的少菌型患者 sCR1 水平较低，从而降低了抗炎反应（分别为 p=0.040 和 p=0.046）。此外，最古老的单体型增加了多菌型临床形式的易感性（OR=3.04，p=0.01），并携带内含子 rs12034383*G 等位基因，该等位基因与更高的基因表达相关（p=0.043），可能增加寄生虫的内化。此外，sCR1 水平与甘露聚糖结合凝集素（补体凝集素途径的起始分子，由 CR1 识别）之间存在负相关（R=-0.52，p=0.007）。
这些结果提示 CR1 多态性对 mRNA 和 sCR1 水平具有调节作用，单体型特异性效应增加了麻风病的易感性，可能通过增强寄生虫的吞噬作用和炎症反应。
