Effects of genetic polymorphism in MHC, KIR, and related loci on human disease

某些免疫反应基因的广泛变异是导致几乎所有人类疾病风险变异的宿主遗传决定因素的核心。我们已经研究了高度多态性的KIR和HLA位点，以及其他相关的、较少多态性的位点对几种疾病的遗传影响。我们对这些效应的一般理解的贡献总结在这里。作为先天免疫系统的一部分，NK细胞是抵御病毒感染和肿瘤的第一道防线。NK细胞的效应功能，如细胞毒性和细胞因子释放，是由来自大量激活和抑制受体的综合信号控制的。NK细胞及其配体HLA I类分子上的杀伤细胞免疫球蛋白样受体（KIRs）在这种严格的调控中起着至关重要的作用。KIR基因簇和HLA I类位点都非常多样化，这导致NK细胞免疫反应在一定程度上是遗传预先决定的假设。我的实验室之前的流行病学观察支持了这一点，即具有激活谱的KIR/HLA复合基因型（即存在激活KIR或缺乏抑制性KIR或其各自的配体）与抵抗HCV和HIV感染，减缓HIV疾病进展以及更好的生殖适应性相关。已经描述了HIV-1疾病进展缓慢与激活NK细胞受体KIR3DS1及其假设配体HLA-B Bw4等位基因在80位异亮氨酸（称为HLA-B Bw4- 80i）的表达之间的显著关联。这些流行病学数据是第一个涉及特异性NK细胞受体基因调节HIV-1发病机制的数据，但这些KIR/HLA复合基因型与HIV-1复制控制和疾病进展之间的流行病学关联的功能基础尚未确定。与哈佛医学院的合作者合作，我们证明NK细胞能够在体外以剂量和细胞接触依赖的方式抑制HIV-1复制。此外，我们发现，相对于不表达KIR3DS1的NK细胞，表达KIR3DS1的NK细胞强烈且显著地抑制了表达HLA-B Bw4-80I的靶细胞中HIV-1的复制。这些数据提供了第一个功能证据，证明KIR位点的变异影响NK细胞活性在遏制HIV-1复制中的有效性，并特别提供了KIR3DS1/HLA-B Bw4-80I复合基因型在HIV-1疾病进展中的保护作用的初步功能关联。这些数据表明，先天免疫系统效应细胞在控制HIV-1复制中的作用比传统认为的更重要，这将有助于指导直接针对先天免疫的抗病毒策略的发展。有研究提出，KIR2DL3/ hla - c1阳性个体对病毒感染的抵抗力提高可能是由于KIR2DL3对NK细胞的抑制作用较KIR2DL1对NK细胞的抑制作用弱。为了表征不同HLA- c等位基因背景下NK细胞的反应性，我们与NIDDK的Barbara Rehermann博士合作，使用甲型流感病毒（IAV）感染的体外模型，研究了具有不同KIR/HLA复合基因型的一组独特且特征明确的受试者中NK细胞反应的动力学。多色流式细胞术显示，在HLA-C1纯合子受试者中，hla -抑制的NK细胞亚群比HLA-C2纯合子受试者中更大，在IFN-分泌和CD107a脱粒检测中反应更快。这些结果提供了KIR/HLA基因型差异NK细胞反应性的功能证据，并可能为病毒感染的差异先天免疫反应性提供有用的见解。总的来说，这些功能研究在解释和确认基因数据方面已经获得了特别的回报，从而为开发潜在的治疗方法提供了可靠的信息。猕猴和黑白眉猴等非人类灵长类动物是开发有效艾滋病疫苗的重要组成部分。我们与威斯康星大学的David Watkins博士合作，证明了MHC I类和II类位点在控制猕猴SIV感染中的重要性。其中，Mamu-B*08、Mamu-DRB1*1003和-DRB1*0306在siv感染的恒河猴精英控制者中富集。来自这些研究的数据可能为理解人类精英控制者中MHC相关免疫保护和病毒遏制的相关关系提供一个很好的模型，并进一步加深我们对HIV疫苗设计的理解。与华盛顿大学的研究人员合作，我们分析了肯尼亚围产期队列中产前接受齐多夫定的母婴HLA一致性和母体HLA纯合性。HLA一致性评分为共享I类等位基因的数量，并根据母体HIV-1载量调整相对风险估计。结果表明，母婴HLA一致性和母体HLA纯合性增加了婴儿HIV-1感染的总体、宫内和母乳传播风险。这些数据与先前的证据一致，表明HLA介导的免疫反应是HIV-1选择和HLA多样性的重要驱动因素。研究结果还表明同种免疫反应在HIV-1垂直传播中的作用，这是有趣的，因为类似的研究表明，一致性和同种免疫反应也可能改变异性恋HIV-1传播的风险。因此，进一步研究HLA I类和II类以及细胞同种免疫反应在HIV-1垂直和异性传播中的作用是有必要的。胎盘位置的自然杀伤细胞表达KIR，可以与滋养细胞上的HLA-C分子结合。这两种基因系统都是多态的，我们之前发现了母体KIR/胎儿HLA-C基因型与先兆子痫的关联。子痫前期和复发性流产（RM）有相同的胎盘缺陷发病机制。与剑桥大学的阿什利·莫菲特博士合作，对患有RM的夫妇进行了基因分型。结果表明，KIR2DS1具有保护作用，因为该基因在RM女性中缺失非常显著。这一发现具有生物学意义，因为KIR2DS1是HLA-C 2组同种异体的激活受体，因此其功能作用将是克服C2-KIR2DL1相互作用介导的强抑制。这一发现有助于反驳滋养层HLA I类分子对入侵滋养层的作用是抑制NK细胞杀伤的普遍观点。许多研究人员发现，子宫NK （uNK）细胞不杀死滋养细胞，而是产生多种细胞因子和趋化因子，调节螺旋动脉的侵袭和归巢。重要的是，在与KIR2DL1结合后，uNK细胞产生的血管生成因子和趋化因子水平降低[摘要在7800个字符处被缩短]

The extensive variation at some of the immune response genes is central amongst the host genetic determinants that contribute to the variability in risk of virtually all human diseases. We have studied the genetic effects of the highly polymorphic KIR and HLA loci, as well as other related, less polymorphic loci on several diseases. Our contributions to the general understanding of these effects are summarized here. As part of the innate immune system, NK cells present the first line of defense against viral infections and tumors. NK cell effector functions, such as cytotoxicity and cytokine release, are controlled by integrated signals from a large panel of both activating and inhibitory receptors. Killer cell immunoglobulin-like receptors (KIRs) on NK cells and their ligands, HLA class I molecules, play an essential part in this tight regulation. Both the KIR gene cluster and the HLA class I loci are extraordinarily diverse, which has led to the hypothesis that NK cell immune responses are genetically predetermined to some extent. This is supported by previous epidemiological observations by my laboratory that KIR/HLA compound genotypes with a supposedly activating profile (i.e., presence of activating KIR or lack of inhibitory KIRs or their respective ligands) are associated with resistance to HCV and HIV infection, slower HIV disease progression, and better reproductive fitness. A significant association has been described between slower HIV-1 disease progression and the expression of an activating NK cell receptor, KIR3DS1, in conjunction with its putative ligand, HLA-B Bw4 alleles with an isoleucine at position 80 (referred to as HLA-B Bw4-80I). These epidemiological data were the first to implicate specific NK cell receptor genes in modulating HIV-1 pathogenesis, but the functional basis of the epidemiological association between these KIR/HLA compound genotypes and control of HIV-1 replication and disease progression have not yet been identified. In conjunction with collaborators at Harvard medical school, we demonstrated that NK cells are able to suppress HIV-1 replication in vitro in a dose- and cell contactdependent manner. Furthermore, we showed that NK cells expressing KIR3DS1 strongly and significantly inhibited HIV-1 replication in target cells expressing HLA-B Bw4-80I relative to NK cells that do not express KIR3DS1. These data provide the first functional evidence that variation at the KIR locus influences the effectiveness of NK cell activity in the containment of HIV-1 replication and specifically provide an initial functional correlate for the protective effect of the KIR3DS1/HLA-B Bw4-80I compound genotype from HIV-1 disease progression described in previous epidemiological studies. These data suggest a more important role of effector cells of the innate immune system in the control of HIV-1 replication than traditionally thought, which will help to guide the development of antiviral strategies directly targeting innate immunity. It has been proposed that improved resistance to virus infections among KIR2DL3/HLA-C1positive individuals may be the result of weaker NK cell inhibition through KIR2DL3 compared with NK cell inhibition through KIR2DL1 in KIR2DL1/HLA-C2positive individuals. In order to characterize NK cell responsiveness in the context of different HLA-C alleles, we collaborated with Dr. Barbara Rehermann at the NIDDK to study the kinetics of NK cell responses in a unique and well-characterized cohort of subjects with distinct KIR/HLA compound genotypes using an in vitro model of infection with influenza A virus (IAV). Multicolor flow cytometry revealed that the HLA-Cinhibited NK cell subset in HLA-C1 homozygous subjects was larger and responded more rapidly in IFN-γ secretion and CD107a degranulation assays than its counterpart in HLA-C2 homozygous subjects. These results provide functional evidence for differential NK cell responsiveness depending on KIR/HLA genotype and may provide useful insights into differential innate immune responsiveness to viral infections. Overall, these functional studies have been exceptionally rewarding in that they explain and confirm the genetic data, and thereby provide solid information to use in development of potential therapies. Nonhuman primates such as macaques and sooty mangabeys are an essential component in the development of an effective AIDS vaccine. In collaboration with Dr. David Watkins at the University of Wisconsin, we have shown the importance of the MHC class I and II loci in the control of SIV infection in macaques. Specifically, Mamu-B*08, Mamu-DRB1*1003 and -DRB1*0306 were enriched in a cohort of SIV-infected Rhesus Macaque Elite Controllers. The data derived from these studies may provide a good model to understand the correlates of MHC associated immune protection and viral containment in human elite controllers and further our understanding of HIV vaccine design. In collaboration with investigators at the University of Washington we analyzed mother-child HLA concordance and maternal HLA homozygosity in a Kenyan perinatal cohort receiving antenatal zidovudine. HLA concordance was scored as the number of shared class I alleles, and relative risk estimates were adjusted for maternal HIV-1 load. The results showed that mother-child HLA concordance and maternal HLA homozygosity increased the risk of HIV-1 infection in infants for overall, in utero, and breast-feeding transmission. These data are consistent with previous evidence indicating that HLA-mediated immune responses are important drivers of HIV-1 selection and HLA diversity. The results also suggest a role for alloimmune responses in vertical transmission of HIV-1, which is intriguing because similar studies have indicated that concordance and alloimmune responses may also alter the risk of heterosexual HIV-1 transmission. Thus, further studies of the role played by HLA class I and II and cellular alloimmune responses in both vertical and heterosexual HIV-1 transmission are warranted. The natural killer cells at the site of placentation express KIR that can bind to HLA-C molecules on trophoblast cells. Both these gene systems are polymorphic and we previously showed an association of particular maternal KIR/fetal HLA-C genotypes in pre-eclampsia. Pre-eclampsia and recurrent miscarriage (RM) share the pathogenesis of defective placentation. In collaboration with Dr. Ashley Moffett at the University of Cambridge, couples with RM were genotyped. The results indicated that KIR2DS1 is protective because the lack of this gene in RM women was highly significant. This finding makes biological sense because KIR2DS1 is the activating receptor for HLA-C group 2 allotypes and so the functional effect would be to overcome the strong inhibition mediated by a C2-KIR2DL1 interaction. The findings help to refute the pervasive idea that the function of trophoblast HLA class I molecules on the invading trophoblast is to inhibit killing by NK cells. Many researchers have found that uterine NK (uNK) cells do not kill trophoblast but instead produce a variety of cytokines and chemokines that modulate invasion and homing to the spiral arteries. Importantly, levels of angiogenic factors and chemokines produced by uNK cells are reduced following KIR2DL1 binding [summary truncated at 7800 characters]