炎症性肠病患者抑制性杀伤细胞免疫球蛋白样受体基因多态性分析

目的 分析炎症性肠病(inflammatory bowel disease,IBD)患者抑制性杀伤细胞免疫球蛋白样受体(killer cell immunoglobulin-like receptor,iKIR)基因多态性,探讨iKIR基因多态性与IBD的关联性.方法 收集100例溃疡性结肠炎(UC)、52例克罗恩病(CD)患者和106名种族匹配的健康对照者外周血DNA标本,采用序列特异性引物聚合酶链反应(PCR-SSP)方法,分析上述对象iKIR基因位点的多态性,计算iKIR基因表型频率和基因频率,比较IBD患者与健康对照者间的差异.结果 iKIR基因(包括KIR2DL1、KIR2DL2、KIR2DL3、KIR2DL4、KIR2DL5、KIR3DL1、KIR3DL2、KIR3DL3)在IBD患者和健康对照组均有不同程度的表达.UC患者KIR2DL1和KIR2DL3表现型频率比健康对照组显著降低(P=0.001),而KIR2DL2、KIR2DL4、KIR2DL5、KIR3DL1、KIR3DL2和KIR3DL3表现型频率与健康对照组比较差异无统计学意义(P＞0.05).CD患者KIR2DL1表现型频率比健康对照组显著降低(P=0.007),而其余iKIR基因表现型频率与健康对照组比较差异无统计学意义(P＞0.05).结论 KIR2DL1和KIR2DL3表现型频率在UC患者中显著下降,提示其与UC的易感性有密切关系; 而KIR2DL1基因可能与CD易感性密切相关.     

CXC趋化因子受体2和白细胞介素-8在炎症性肠病患者中的表达及其意义

背景:CXC趋化因子受体2(CXCR2)为G蛋白耦联受体超家族成员,主要参与肿瘤生长、血管形成以及炎症性疾病的发病,有研究显示其参与炎症性肠病(IBD)发病,但相关作用仍未明确。研究表明白细胞介素-8(IL-8)与CXCR1和CXCR2的相互作用在IBD发病中发挥重要作用。目的:探讨CXCR2和IL-8在IBD患者中的表达及其意义。方法:纳入武汉大学中南医院2013年10月—2014年12月收治的活动期IBD患者121例,分为克罗恩病(CD)组和溃疡性结肠炎(UC)组,选取70例同期健康体检者作为正常对照(HC)组。采用real-time PCR检测外周血和肠黏膜组织IL-8和CXCR2 mRNA表达;采用蛋白质印迹法检测肠黏膜组织CXCR2蛋白表达。结果:UC组外周血IL-8 mRNA表达水平显著高于HC组(P=0.017);CD组、UC组和HC组外周血CXCR2 mRNA表达水平无明显差异(P=0.285)。CD组、UC组和HC组肠黏膜组织IL-8 mRNA表达水平无明显差异(P=0.206);CD组和UC组肠黏膜组织CXCR2 mRNA表达水平显著高于HC组(P=0.002;P0.001),且UC组显著高于CD组(P=0.005)。UC组和CD组肠黏膜组织CXCR2蛋白表达水平高于HC组(P=0.049;P=0.080)。结论:IBD患者肠黏膜组织CXCR2 mRNA和蛋白表达均显著上调,且以UC患者为著,下调肠黏膜CXCR2表达可为治疗UC提供新靶点。IL-8主要在UC患者外周血中高表达,提示IL-8主要与UC发病相关。     

HO-1在炎症性肠病中的表达及其与疾病活动度的关系

目的 探讨血红素氧化酶-1(HO-1)在炎症性肠病（IBD）中的表达及其与疾病活动度的关系。方法 选择2020年1月至2022年3月四川绵阳四〇四医院收治的76例IBD患者纳入研究组,其中溃疡性结肠炎（UC）有40例（设为UC组）,克罗恩病（CD）有36例（设为CD组）;另选择同期在该院体检的50名健康志愿者纳入对照组。收集所有受试者的外周血样本和肠黏膜组织,采用ELISA法测定外周血HO-1的表达水平,采用免疫组织化学染色SABC法测定肠黏膜组织中HO-1的表达水平。采用ROC曲线分析IBD患者外周血和肠黏膜组织中HO-1的表达水平对疾病的诊断效能。根据改良Mayo内镜评分（IMES）评估UC患者疾病活动度,根据克罗恩病活动指数（CDAI）评估CD患者疾病活动度。采用Pearson相关系数法分析IBD患者外周血和肠黏膜组织中HO-1的表达水平与疾病活动度的相关性。结果 UC组和CD组外周血和肠黏膜组织中HO-1的表达水平均显著高于对照组,差异均有统计学意义（P均<0.01）。联合外周血和肠黏膜组织中HO-1的表达水平诊断IBD的敏感度、特异度、准确度和曲线下面积（AUC）分别为...     

炎症性肠病患者血浆Frat1水平及其临床意义

进展期T细胞淋巴瘤常见重排蛋白1（Frat 1）作为Wnt信号转导通路的激活蛋白在胚胎发育、肿瘤发生等过程中发挥作用,而Wnt信号通路异常与炎症性肠病（IBD）的发病相关.目的：探讨活动性IBD患者血浆Frat 1水平及其临床意义.方法：纳入2009年6月-2010年5月上海华东医院42例克罗恩病（CD）患者、55例溃疡性结肠炎（UC）患者和56名正常对照者,应用酶联免疫吸附测定（ELISA）检测血浆Frat 1水平,以受试者工作特征（ROC）曲线分析血浆Frat 1水平对IBD的诊断价值,应用Pearson相关分析研究血浆Frat 1水平与临床疾病活动性的相关性.结果：UC患者血浆Frat 1水平显著低于正常对照组（6.55 pg/ml对17.81 pg/m1,P〈0.001）,CD患者血浆Frat 1水平与正常对照组相比差异无统计学意义（P=0.8995）.ROC曲线分析表明血浆Frat 1水平对鉴别UC患者和正常对照者无意义（P=0.2736）.UC患者血浆Frat 1水平与红细胞沉降率（P=0.5994）,C反应蛋白（P=0.4685）和Mayo评分（P=0.3663）之间均无相关性.结论：UC患者血浆Frat 1水平降低,可能与UC的发生存在潜在的联系.     

炎症性肠病患者血清和肠黏膜组织中miR-31-3p的表达水平及临床意义

目的 观察炎症性肠病（IBD）患者血清和肠黏膜组织中miR-31-3p的表达情况,并分析其在疾病诊断和病情评估中的应用价值。方法 随机选取2019年6月至2021年6月成都大学附属医院消化内科收治住院的符合纳入及排除标准的95例IBD患者（设为IBD组）,其中克罗恩病（CD）有33例（设为CD组）,溃疡性结肠炎（UC）有62例（设为UC组）;同期招募67名健康志愿者作为对照组。收集受试对象的肠黏膜组织及血清样本,采用实时荧光定量PCR技术检测血清和肠黏膜组织中miR-31-3p的表达水平,并分析其在IBD组与对照组,以及不同活动度IBD患者间的差异。采用Pearson相关系数法分析血清和肠黏膜组织中miR-31-3p的表达水平与IBD患者疾病活动度的相关性;采用ROC曲线分析血清和肠黏膜组织中miR-31-3p对IBD的诊断及病情评估的价值。结果 CD组和UC组患者血清和肠黏膜组织中miR-31-3p的表达水平均显著高于对照组（P<0.05）。轻度活动期、中度活动期、重度活动期的CD和UC患者血清和肠黏膜组织中miR-31-3p的表达水平均依次升高,组间比较差异均有统计学意义（P...     

炎症性肠病患者杀伤细胞抑制性受体的表达及临床意义

杀伤细胞抑制性受体(killer cell inlaibitory receptors,KIR)主要表达在自然杀伤(NK)细胞和CD8+ T细胞,以及少量CD4+ T细胞,可特异地与HLA-Ⅰ类分子结合,传递负反馈信号,抑制NK细胞和T细胞的生物学活性[1-2].KIR基因参与了许多疾病的发生,如器官移植排斥反应、自身免疫性疾病和产前子痫等[1-2].本研究分析了炎症性肠病(IBD)患者外周血和肠黏膜固有层内NK和T细胞KIR的表达,包括CD158a(KIR 2DL1)、KIR-NKAT2(KIR 2DL3)和NKB1(KIR3DL1),并探讨其在疾病发生过程中的作用.     

单核样髓源性抑制细胞在炎症性肠病中的表达及其临床意义

背景：近年来炎症性肠病（IBD）发病率呈上升趋势,其病理生理学机制复杂且仍未明确。目的：研究单核样髓源性抑制细胞（MDSCs）在IBD患者外周血单核细胞中的比例,分析单核样MDSCs与IBD活动性的关系,从而初步探讨单核样MDSCs在IBD中的作用机制。方法：纳入IBD患者60例,分为克罗恩病（CD）组（n=33）和溃疡性结肠炎（UC）组（n=27）,选取30名同期健康体检者作为正常对照组,采用流式细胞仪检测CD组、UC组、正常对照组患者外周血单核样MDSCs／单核细胞比例,分析单核样MDSCs与IBD患者WBC、PLT、ESR、CRP的相关性。结果：CD组和UC组外周血单核样MDSCs／单核细胞比例较正常对照组相比显著升高[（43．7±23．0）％、（49．1±27．2）％对（10．7±7．4）％]（P〈0．01）,CD组与UC组相比差异无统计学意义（P〉0．05）。活动期CD和UC组外周血单核样MDSCs／单核细胞比例均较缓解期组显著升高[（60．3±16．8）％、（66．3±17．6）％对（28．1±16．2）％、（19．9±9．0）％]（P〈0．01）。IBD患者外周血单核样MDSCs／单核细胞比例与WBC计数、PLT计数呈正相关（r=0．44,P=0．02;r=0．43,P=0．02）,与ESR、CRP不相关（r=0．33,P=0．08;r=0．30,P=0．12）。结论：IBD患者外周血单核样MDSCs比例明显升高,与IBD活动性密切相关。单核样MDSCs在IBD发病中具有重要作用。     

FOXP3在炎症性肠病患者外周血和肠黏膜中的表达特点

背景：炎症性肠病（IBD）的发病与一系列免疫异常有关。免疫反应受特定的免疫调节细胞调控，包括CD4^＋CD25^＋T细胞．而CD4^＋CD25^＋T细胞的发育和功能可能受FOXP3基因调控。目的：研究FOXP3的表达特点以及IBD时FOXP3表达的改变。方法：以免疫磁珠分离CD4^＋、CD4^＋CD25^＋和CD4^＋CD25^-T细胞。以逆转录聚合酶链反应（RT-PCR）和蛋白质印迹法检测IBD患者和非IBD对照外周血单个核细胞（PBMC）、肠固有层单个核细胞（LPMC）和肠黏膜组织中FOXP3的表达。结果：CD4^＋CD25^＋T细胞中FOXP3 mRNA的表达明显强于CD4^＋T细胞和未分离的PBMC或LPMC。T细胞受体（TCR）激活后，或经白细胞介素（IL）-2、IL-15作用后，PBMC或LPMC FOXP3 mRNA或蛋白表达明显增强。12例IBD中9例（75．0％）肠黏膜LPMC中检测到FOXP3 mRNA表达，高于对照肠黏膜的47．1％（8／17．P〉0．05）。未受刺激的IBD和对照肠黏膜组织中未检测到FOXP3 mRNA表达。结论：人类FOXP3的表达受T细胞活化影响。IBD患者肠黏膜LPMC中FOXP3 mRNA的表达率有增高的趋势．但与对照肠黏膜相比无显著差异．     

白细胞免疫球蛋白活化受体3与炎症性肠病的关系研究

[目的]探讨中国汉族人群中白细胞免疫球蛋白活化受体A3(LILRA3)基因多态性与炎症性肠病(IBD)发病的关系。[方法]收集378例确诊IBD患者[溃疡性结肠炎(UC)组193例,克罗恩病(CD)组185例]和509例健康者(正常对照组),通过连接酶检测反应-聚合酶链反应(LDR-PCR)技术分析LILRA3基因第1内含子第161位碱基(G→C突变)多态性。对所有入选者使用实时定量PCR(qRT-PCR)方法检测外周血、肠黏膜中LILRA3mRNA表达情况,使用Western blotting方法检测肠黏膜中LILRA3蛋白表达。[结果]所有纳入样本中均未发现LILRA3基因第1内含子第161位的纯合子突变(CC)。CD组患者该位点突变基因型频率与等位基因频率均明显低于正常对照组,差异具有统计学意义(P值分别为0.017,0.021),且突变基因型GC及突变等位基因C是CD发病的保护因素(OR=0.489,95%CI:0.269~0.890;OR=0.509,95%CI:0.284~0.914)。基因型与临床表型相关性分析提示:突变基因型GC与CD17-40岁发病及CD炎症型疾病行为相关(P值分别为0.039,0.049),且均是保护性因素(OR=0.490,95%CI:0.245~0.977;OR=0.473,95%CI:0.221~0.953)。UC组与正常对照组相比该位点基因型频率与等位基因频率分布无差异(P0.05)。qRT-PCR结果提示:1 CD组、UC组患者外周血LILRA3mRNA表达量均明显高于正常对照组[(14.25±2.29)、(15.71±2.74)∶(7.54±1.26)],差异具有统计学意义(P值分别为0.035,0.025);2突变个体(GC)LILRA3表达量明显高于野生型个体(GG)[(27.58±3.70)∶(10±1.39)],差异具有统计学意义(P0.001);3 CD、UC组患者肠黏膜LILRA3mRNA表达量也明显高于正常对照组[(14.31±0.88)、(13.87±0.98)∶(2.29±2.88)],差异具有统计学意义(P0.001)。与对照组相比,CD组、UC组肠黏膜LILRA3蛋白表达量均明显升高[(0.55±0.82)、(0.59±0.13)∶(0.27±0.09)],差异具有统计学意义(P0.001)。[结论]LILRA3基因第1内含子第161位基因多态性与IBD发病相关,且突变影响其mRNA表达。IBD患者外周血及肠黏膜中LILRA3表达量均较正常对照者增高,提示LILRA3可能是IBD的一个新的致病基因。     

骨桥蛋白在炎症性肠病患者结肠组织中的表达

背景：骨桥蛋白（OPN）是一种分泌型磷酸化糖蛋白,参与细胞信号转导,促进细胞黏附和迁移。近年研究发现炎症性肠病（IBD）患者血浆OPN水平升高,患者结肠黏膜中可检出OPN表达。目的：了解OPN在IBD患者结肠黏膜组织中的表达情况,探讨其在IBD发病机制中的作用。方法：以免疫组化半定量方法检测53例溃疡性结肠炎（UC）、62例克罗恩病（CD）和15例源自结肠腺瘤患者的正常结肠组织标本中OPN的表达。结果：OPN广泛表达于结肠黏膜上皮细胞和固有层渗出细胞。UC组和CD组结肠上皮细胞的OPN平均光密度值显著低于对照组（11．84±0．98和10．04±1．37对12．64±1．45,P〈0．05）,结肠黏膜固有层渗出细胞的OPN阳性细胞百分率则显著高于对照组（20．31％±4．50％和12．69％±3．06％对3．85％±0．66％,P〈0．001）。UC和CD患者的病情严重程度与结肠上皮细胞和固有层渗出细胞中的OPN表达量均无相关性。结论：OPN在IBD患者结肠黏膜上皮和同有层中的表达不一致,结肠上皮细胞中OPN表达下调可能与肠黏膜屏障功能受损有关,而黏膜固有层渗出细胞中OPN表达上调可能与免疫反应有关。     

Inhibitory Killer Cell Immunoglobulin-Like Receptor KIR3DL1 in Combination with HLA-B Bw4iso Protect against Ankylosing Spondylitis

Background: The HLA class I molecules serve as ligands for both T cell receptors and killer cell immunoglobulin-like receptors (KIRs). Objective: We investigated the HLAC and HLA-Bw4 alleles as well as KIRs expression on CD56 positive lymphocytes to evaluate whether these genes and molecules could influence Ankylosing spondylitis (AS) susceptibility, alone or in combination. Methods: We typed 40 AS patients and 40 normal controls for HLA-C asn80 (group 1) and HLA-C lys80 (group 2), HLA-B Bw4thero, HLA-B Bw4iso and HLA-A Bw4 alleles by PCR-SSP method. We also assessed the expression of KIR2DL1/2DS1, KIR2DL2/2DL3, KIR3DL1 and KIR2DS4 by flow cytometry. The Pearson chi-square or Fisher exact test was performed for statistical analysis. Results: The frequency of HLA-B Bw4iso but not HLA-B Bw4thero and HLA-A Bw4, ligand for the inhibitory KIR3DL1, was significantly reduced in AS patients as compared with controls (p<0.01). No significant differences were observed in gene carrier frequencies of HLA-C group 1 and 2 between AS and controls. Although no differences were found in the expression of KIR receptors between AS and normal subjects, we found that expression of KIR3DL1 in the presence of HLA Bw4-Biso gene was reduced in patients with AS compared to healthy controls (p<0.009). Conclusion: We conclude that HLA-B Bw4iso, the ligand of inhibitory KIR3DL1, with and without the expression of KIR3DL1 might be involved in protection against AS. Our results suggest that besides the HLA and KIR genotype, expression levels of KIRs may be involved in the pathogenesis of AS disease     

Expansion and enhanced survival of natural killer cells expressing the killer immunoglobulin-like receptor KIR3DL2 in spondylarthritis

OBJECTIVE: The spondylarthritides (SpA) are strongly associated with possession of HLA-B27. We hypothesized that the expression of abnormal forms of HLA-B27 in SpA may have a pathogenic role through interaction with cells bearing natural killer (NK) receptors, in particular, killer immunoglobulin-like receptor (KIR) KIR3DL2, a receptor for HLA-B27 homodimer (B27(2)). We therefore undertook the present study to determine the number and function of NK and T cells bearing KIR3DL2 in SpA. METHODS: Expression of KIR3DL2 on NK and T cells was quantified in peripheral blood (PB) from 35 patients with SpA and 5 patients with juvenile enthesitis-related arthritis (juvenile ERA); samples were compared with samples from healthy and rheumatoid arthritis (RA) controls. Paired synovial fluid (SF) was studied where available. Expression of other KIRs as well as activation, memory, and homing markers on KIR3DL2+ NK and T cells was quantified. NK cell survival was assessed using the apoptotic markers annexin V and 7-aminoactinomycin D, and cytotoxicity by (51)Cr release assay. RESULTS: In SpA, an increased number of PB and SF NK and CD4+ T cells expressed the KIR3DL2 receptor compared with controls. In ERA, KIR3DL2 expression was increased in PB and SF CD4 T cells (and SF NK cells) compared with RA controls. KIR3DL2+ NK cells had an activated phenotype, and were protected from apoptosis by culture with a cell line expressing B27(2). SpA PB mononuclear NK cells from SpA patients showed greater cytotoxicity than those from controls. CONCLUSION: KIR3DL2 expression on NK cells and CD4 lymphocytes is increased in SpA and ERA. These cells are activated and may have a pathogenic role.     

Under representation of the inhibitory KIR3DL1 molecule and the KIR3DL1+/BW4+ complex in HIV exposed seronegative individuals

The activation of natural killer (NK) cells is modulated by surface molecules. We analyzed NK cells in human immunodeficiency virus (HIV)-exposed seronegative (HESN) individuals by means of molecular typing of HLA B, Cw, and killer cell immunoglobulin-like receptor (KIR) molecules. In HESN individuals, compared with HIV patients, the frequency of the inhibitory KIR3DL1 allele and of the KIR3DL1(+)/Bw4(+) inhibitory complex was reduced, whereas that of the activatory KIR3DS1(+) ligand and the activatory Bw4(+)/3DL1(-)/3DS1(+) complex was increased, resulting in a statistically significant diversion from Hardy-Weinberg equilibrium (KIR3DS1 homozygote) in HESN individuals. The reciprocal equilibrium between inhibitory and activatory NK receptors and their ligands favors NK activation in HESN individuals.     

The KIR2DS2/DL2 genotype is associated with adult persistent/chronic and relapsed immune thrombocytopenia independently of FCGR3a-158 polymorphisms

Adult immune thrombocytopenia (ITP) is a heterogeneous disease and its immunobiology is incompletely understood. Establishing associations between candidate genes and ITP susceptibility may provide insight into pathogenesis. Previous studies have associated overrepresentation of FCGR3a-V158 allele with pediatric ITP. We prospectively accrued DNA from 102 adult patients with persistent/chronic or relapsed primary ITP identified by defined criteria. The distribution of KIR2 genes and polymorphisms of FCGR3a, both associated with autoimmunity, were compared with 105 healthy white individuals. Results were stratified by ethnicity. Carriers of the KIR2DS2/KIR2DL2 genotype [KIR2DS2/KIR2DL2 versus KIR2DS2/KIR2DL2 and KIR2DS2/KIR2DL2; odds ratio (OR) 2.51, P = 0.002] were overrepresented. In addition, frequency of the high-binding affinity FCGR3a-V/V158 genotype (VV versus VF/FF; OR = 3.05, P = 0.007) was increased, whereas that of the FCGR3a-F158 allele was reduced (OR = 2.58, P = 0.00.002). In a regression model to adjust for age, sex and the effects of the other gene, the KIR2 genotype independently conferred increased susceptibility from the FCGR3a-158 polymorphisms. In a comparison of healthy controls and a tightly defined cohort of adult ITP patients, the KIR2DS2/KIR2DL2 genotype was found to be associated with ITP independently of FCGR3a-158 polymorphisms. Further studies are required to establish the mechanistic basis for these observations and their potential impact on immune-based therapies.     

Expansion and enhanced survival of natural killer cells expressing the killer immunoglobulin‐like receptor KIR3DL2 in spondylarthritis

Objective

The spondylarthritides (SpA) are strongly associated with possession of HLA–B27. We hypothesized that the expression of abnormal forms of HLA–B27 in SpA may have a pathogenic role through interaction with cells bearing natural killer (NK) receptors, in particular, killer immunoglobulin‐like receptor (KIR) KIR3DL2, a receptor for HLA–B27 homodimer (B27₂). We therefore undertook the present study to determine the number and function of NK and T cells bearing KIR3DL2 in SpA.

Methods

Expression of KIR3DL2 on NK and T cells was quantified in peripheral blood (PB) from 35 patients with SpA and 5 patients with juvenile enthesitis‐related arthritis (juvenile ERA); samples were compared with samples from healthy and rheumatoid arthritis (RA) controls. Paired synovial fluid (SF) was studied where available. Expression of other KIRs as well as activation, memory, and homing markers on KIR3DL2+ NK and T cells was quantified. NK cell survival was assessed using the apoptotic markers annexin V and 7‐aminoactinomycin D, and cytotoxicity by ⁵¹Cr release assay.

Results

In SpA, an increased number of PB and SF NK and CD4+ T cells expressed the KIR3DL2 receptor compared with controls. In ERA, KIR3DL2 expression was increased in PB and SF CD4 T cells (and SF NK cells) compared with RA controls. KIR3DL2+ NK cells had an activated phenotype, and were protected from apoptosis by culture with a cell line expressing B27₂. SpA PB mononuclear NK cells from SpA patients showed greater cytotoxicity than those from controls.

Conclusion

KIR3DL2 expression on NK cells and CD4 lymphocytes is increased in SpA and ERA. These cells are activated and may have a pathogenic role.

     

Association of the KIR3DS1*013 and KIR3DL1*004 alleles with susceptibility to ankylosing spondylitis

Objective

The killer cell immunoglobulin‐like receptors (KIRs) form a group of regulatory molecules that specifically recognize HLA class I molecules. The aim of this study was to analyze the possible contribution of the KIR3DL1 and KIR3DS1 alleles, in addition to HLA–B27, in the susceptibility to ankylosing spondylitis (AS) in a population of individuals from Spain.

Methods

We genotyped the KIR3DS1 and KIR3DL1 alleles in 2 cohorts of patients with AS and healthy control subjects. In total, 270 patients with AS and 435 healthy, HLA–B27–positive matched control subjects from Spain were enrolled. The KIR3DS1 and KIR3DL1 alleles were genotyped by sequence‐specific oligonucleotide probe–polymerase chain reaction, and their association with AS was analyzed. All individuals were typed for HLA–B.

Results

The KIR3DS1*013 allele was solely responsible for the increased frequency of the activator receptor KIR3DS1 in patients with AS compared with healthy HLA–B27–positive control subjects (35.7% versus 22.6% [P = 10⁻⁶], odds ratio 1.90, 95% confidence interval 1.50–2.40). The increased frequency of the KIR3DS1*013 allele in patients with AS was independent of the presence or absence of the HLA–Bw4I80 epitope. Moreover, the null allele KIR3DL1*004 was a unique inhibitory KIR3DL1 allele that showed a negative association with AS in the presence of HLA–Bw4I80.

Conclusion

The increased frequency of the KIR3DS1*013 allele in patients with AS is clearly independent of the presence of the HLA–Bw4I80 epitope, whereas the presence of inhibitory allotypes such as KIR3DL1*004 demonstrated a negative association in patients with AS in the presence of HLA–Bw4I80. As a consequence, the influence of KIR genotypes on AS susceptibility would be mediated by a general imbalance between protective/inhibitory and risk/activating allotypes.

     

Co-evolution of KIR2DL3 with HLA-C in a human population retaining minimal essential diversity of KIR and HLA class I ligands

Natural killer (NK) cells contribute to immunity and reproduction. Guiding these functions, and NK cell education, are killer cell Ig-like receptors (KIR), NK cell receptors that recognize HLA class I. In most human populations, these highly polymorphic receptors and ligands combine with extraordinary diversity. To assess how much of this diversity is necessary, we studied KIR and HLA class I at high resolution in the Yucpa, a small South Amerindian population that survived an approximate 15,000-year history of population bottleneck and epidemic infection, including recent viral hepatitis. The Yucpa retain the three major HLA epitopes recognized by KIR. Through balancing selection on a few divergent haplotypes the Yucpa maintain much of the KIR variation found worldwide. HLA-C*07, the strongest educator of C1-specific NK cells, has reached unusually high frequency in the Yucpa. Concomitantly, weaker variants of the C1 receptor, KIR2DL3, were selected and have largely replaced the form of KIR2DL3 brought by the original migrants from Asia. HLA-C1 and KIR2DL3 homozygosity has previously been correlated with resistance to viral hepatitis. Selection of weaker forms of KIR2DL3 in the Yucpa can be seen as compensation for the high frequency of the potent HLA-C*07 ligand. This study provides an estimate of the minimal KIR-HLA system essential for long-term survival of a human population. That it contains all functional elements of KIR diversity worldwide, attests to the competitive advantage it provides, not only for surviving epidemic infections, but also for rebuilding populations once infection has passed.     

Crystal structure of the HLA-Cw3 allotype-specific killer cell inhibitory receptor KIR2DL2

Killer cell inhibitory receptors (KIR) protect class I HLAs expressing target cells from natural killer (NK) cell-mediated lysis. To understand the molecular basis of this receptor-ligand recognition, we have crystallized the extracellular ligand-binding domains of KIR2DL2, a member of the Ig superfamily receptors that recognize HLA-Cw1, 3, 7, and 8 allotypes. The structure was determined in two different crystal forms, an orthorhombic P212121 and a trigonal P3221 space group, to resolutions of 3.0 and 2.9 A, respectively. The overall fold of this structure, like KIR2DL1, exhibits K-type Ig topology with cis-proline residues in both domains that define beta-strand switching, which sets KIR apart from the C2-type hematopoietic growth hormone receptor fold. The hinge angle of KIR2DL2 is approximately 80 degrees, 14 degrees larger than that observed in KIR2DL1 despite the existence of conserved hydrophobic residues near the hinge region. There is also a 5 degrees difference in the observed hinge angles in two crystal forms of 2DL2, suggesting that the interdomain hinge angle is not fixed. The putative ligand-binding site is formed by residues from several variable loops with charge distribution apparently complementary to that of HLA-C. The packing of the receptors in the orthorhombic crystal form offers an intriguing model for receptor aggregation on the cell surface.     

HLA-B*57:01 Complexed to a CD8 T-Cell Epitope from the HSV-2 ICP22 Protein Binds NK and T Cells through KIR3DL1

HLA-B*57:01 is an HLA allelic variant associated with positive outcomes during viral infections through interactions with T cells and NK cells, but severe disease in persons treated with the anti-HIV-1 drug abacavir. The role of HLA-B*57:01 in the context of HSV infection is unknown. We identified an HLA-B*57:01-restricted CD8 T-cell epitope in the ICP22 (US1) protein of HSV-2. CD8 T cells reactive to the HSV-2 ICP22 epitope recognized the orthologous HSV-1 peptide, but not closely related peptides in human IFNL2 or IFNL3. Abacavir did not alter the CD8 T-cell recognition of the HSV or self-derived peptides. Unexpectedly, a tetramer of HSV-2 ICP22 epitope (228–236) and HLA-B*57:01 bound both CD8 T cells and NK cells. Tetramer specificity for KIR3DL1 was confirmed using KIR3DL1 overexpression on non-human primate cells lacking human KIR and studies with blocking anti-KIR3DL1 antibody. Interaction with KIR3DL1 was generalizable to donors lacking the HLA-B*57:01 genotype or HSV seropositivity. These findings suggest a mechanism for the recognition of HSV infection by NK cells or KIR-expressing T cells via KIR3DL1.