Defining the Binding Region in Factor H to Develop a Therapeutic Factor H-Fc Fusion Protein against Non-Typeable Haemophilus influenzae.
Defining the Binding Region in Factor H to Develop a Therapeutic Factor H-Fc Fusion Protein against Non-Typeable Haemophilus influenzae.
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DOI：
10.3389/fcimb.2016.00040
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发表时间：
2016
影响因子：
5.7
通讯作者：
Akerley BJ
中科院分区：
文献类型：
--
作者：
Wong SM;Shaughnessy J;Ram S;Akerley BJ
非分型流感嗜血杆菌(NTHi)可引起一系列疾病，包括中耳炎、鼻窦炎和慢性阻塞性肺疾病的加重，这些感染导致抗生素耐药性问题，本身往往对标准抗生素治疗方案难以治愈。我们研究了一种策略，利用补体抑制因子H(FH)与NTHi的结合作为免疫治疗的功能靶点，该免疫治疗包含FH的NTHi结合区域与IgG1的Fc区域融合。含有大多数FH结合细菌用来与人FH结合的区域的嵌合蛋白被评估与NTHi结合。7株NTHi临床分离株均与FH6、7/Fc强结合，并能有效促进正常人血清对补体介导的杀伤作用。FH18-20/Fc与其中3株有弱结合，但不促进补体依赖性杀伤。外膜蛋白P5参与了NTHi与FH的结合，在所测试的7株P5缺乏的等基因突变株中，有5株FH6，7/Fc结合显著降低，这意味着在一些菌株中存在另一种FH结合蛋白。1株P5突变株的FH18-20/Fc结合力降低。用小鼠模型评价FH6，7/FC的潜在治疗应用。FH6，7/Fc能有效促进C3与小鼠血清中NTHi的结合，FH6，7/Fc鼻腔给药可显著提高NTHi在肺中的清除。此外，在肺模型中，P5缺陷突变株的存活能力减弱，这表明缺乏P5的逃逸突变株不太可能取代对FH6，7/FC敏感的菌株。这些结果为FH6，7/FC作为治疗NTHi肺部感染的潜在用途提供了证据。FH结合是许多呼吸道病原体的共同特性，FH/Fc嵌合体可能是治疗此类感染的有前途的替代或辅助疗法，这些感染通常是多菌的。
Non-typeable Haemophilus influenzae (NTHi) cause a range of illnesses including otitis media, sinusitis, and exacerbation of chronic obstructive pulmonary disease, infections that contribute to the problem of antibiotic resistance and are themselves often intractable to standard antibiotic treatment regimens. We investigated a strategy to exploit binding of the complement inhibitor Factor H (FH) to NTHi as a functional target for an immunotherapeutic containing the NTHi binding domain of FH fused to the Fc domain of IgG1. Chimeric proteins containing the regions that most FH-binding bacteria use to engage human FH, domains 6 and 7 (FH6,7/Fc) and/or 18 through 20 (FH18–20/Fc), were evaluated for binding to NTHi. FH6,7/Fc bound strongly to each of seven NTHi clinical isolates tested and efficiently promoted complement-mediated killing by normal human serum. FH18–20/Fc bound weakly to three of the strains but did not promote complement dependent killing. Outer-membrane protein P5 has been implicated in FH binding by NTHi, and FH6,7/Fc binding was greatly diminished in five of seven P5 deficient isogenic mutant strains tested, implicating an alternative FH binding protein in some strains. Binding of FH18–20/Fc was decreased in the P5 mutant of one strain. A murine model was used to evaluate potential therapeutic application of FH6,7/Fc. FH6,7/Fc efficiently promoted binding of C3 to NTHi exposed to mouse serum, and intranasal delivery of FH6,7/Fc resulted in significantly enhanced clearance of NTHi from the lung. Moreover, a P5 deficient mutant was attenuated for survival in the lung model, suggesting that escape mutants lacking P5 would be less likely to replace strains susceptible to FH6,7/Fc. These results provide evidence for the potential utility of FH6,7/Fc as a therapeutic against NTHi lung infection. FH binding is a common property of many respiratory tract pathogens and FH/Fc chimeras may represent promising alternative or adjunctive therapeutics against such infections, which are often polymicrobial.