Mukherjee Suprabhat, Mukherjee Sandip, Maiti Tushar K, Bhattacharya Samir, Sinha Babu Santi P
Department of Zoology (Centre for Advanced Studies), Visva-Bharati University, West Bengal, India.
Regional Centre for Biotechnology, Haryana (NCR Delhi), India.
J Infect Dis. 2017 Mar 15;215(6):954-965. doi: 10.1093/infdis/jix067.
Lymphatic filariasis, frequently caused from Wuchereria bancrofti infection, is endemic in several parts of the globe and responsible for human health problems and socioeconomic loss to a large extent. Inflammatory consequences originating from host-parasite interaction play a major role in the disease pathology and allied complications. The identity of the key mediator of this process is yet unknown in filarial research.
Microfilarial protein (MfP) was isolated from the sheath of W. bancrofti microfilariae through ultrafiltration, followed by chromatographic separation. Expression of signaling molecules was studied by enzyme-linked immunosorbent assay and immunoblotting. Binding of MfP to Toll-like receptor 4 (TLR4) was determined by co-immunoprecipitation, fluorescein isothiocyanate-probing, and surface plasmon resonance analysis.
We found that MfP (approximately 70 kDa) binds to macrophage-TLR4 and triggers nuclear factor kappa beta activation that upregulates secretion of proinflammatory cytokines. Microfilarial protein failed to induce inflammation in either TLRKO macrophage or macrophage treated with TLR4 inhibitor, indicating that MfP acts through TLR4. We have also detected phenotypic transformation of macrophages from anti-inflammatory (M2) to proinflammatory (M1) subtype after incubation with MfP.
Microfilarial protein appears to be a new ligand of TLR4 from W. bancrofti. Determination of its functional attributions in the host-parasite relationship, especially immunopathogenesis of filarial infection, may improve our understanding.
淋巴丝虫病常由班氏吴策线虫感染引起，在全球多个地区呈地方性流行，在很大程度上导致人类健康问题和社会经济损失。宿主 - 寄生虫相互作用引发的炎症后果在疾病病理及相关并发症中起主要作用。在丝虫病研究中，这一过程的关键介质身份尚不清楚。
通过超滤从班氏吴策线虫微丝蚴的鞘中分离微丝蚴蛋白（MfP），随后进行色谱分离。通过酶联免疫吸附测定和免疫印迹研究信号分子的表达。通过免疫共沉淀、异硫氰酸荧光素检测和表面等离子体共振分析确定MfP与Toll样受体4（TLR4）的结合。
我们发现MfP（约70 kDa）与巨噬细胞 - TLR4结合并触发核因子κB激活，从而上调促炎细胞因子的分泌。微丝蚴蛋白在TLRKO巨噬细胞或用TLR4抑制剂处理的巨噬细胞中均未能诱导炎症，表明MfP通过TLR4发挥作用。我们还检测到与MfP孵育后巨噬细胞从抗炎（M2）亚型向促炎（M1）亚型的表型转化。
微丝蚴蛋白似乎是班氏吴策线虫TLR4的新配体。确定其在宿主 - 寄生虫关系中的功能归属，特别是丝虫感染的免疫发病机制，可能会增进我们的理解。
