Association of killer cell immunoglobulin‐like receptor genotypes with microscopic polyangiitis

Objective

Genetic background and infection have been implicated in the etiology of microscopic polyangiitis (MPA). Killer cell immunoglobulin‐like receptors (KIRs) are a diverse family of activating and inhibitory receptors expressed on natural killer (NK) cells and T cells, the genes of which show extreme polymorphism. Some KIRs bind to HLA class I subgroups, and genetic interactions between KIR genes and their ligand HLA have been shown to be associated with several autoimmune and viral diseases. In this study, we examined possible associations of the presence or absence of KIR loci with a genetic predisposition to MPA.

Methods

The presence or absence of 14 KIR loci was determined in 57 myeloperoxidase antineutrophil cytoplasmic antibody–positive Japanese subjects (43 patients with MPA and 239 healthy controls).

Results

The carrier frequency of activating KIR2DS3 was significantly decreased among patients with MPA compared with healthy controls (4.7% versus 16.7%; P = 0.038, odds ratio [OR] 0.24, 95% confidence interval [95% CI] 0.06–0.94). When KIRs were analyzed in combination with their HLA ligands, the proportion of individuals carrying inhibitory KIR3DL1 and HLA–Bw4 but not activating receptor KIR3DS1, a combination presumed to be the most inhibitory of all KIR3DS1/3DL1/HLA–B combinations, was significantly increased in the MPA group compared with the control group (46.5% versus 27.0%; P = 0.014, OR 2.35, 95% CI 1.18–4.70). Furthermore, when subjects were classified according to KIR3DL1/3DS1/HLA–B and KIR2DL1/ HLA–C combinations, an increasing trend toward susceptibility was observed as combinations became more inhibitory.

Conclusion

The decreased activation potential of NK and/or T cells associated with KIR/HLA genotypes may predispose to MPA, possibly through insufficient resistance against infections.

     

Detection of autoantibodies to killer immunoglobulin‐like receptors using recombinant fusion proteins for two killer immunoglobulin‐like receptors in patients with systemic autoimmune diseases

Objective

To investigate the existence of autoantibodies to killer immunoglobulin‐like receptors (KIRs), especially p58.1 (KIR2DL1) and p58.2 (KIR2DL3), in patients with systemic autoimmune diseases.

Methods

Sera from 30 patients with systemic lupus erythematosus (SLE), 30 patients with rheumatoid arthritis (RA), 22 patients with Behçet's disease, and 20 healthy control subjects were tested for anti‐p58.1 and anti‐p58.2 antibodies by Western blot analysis using recombinant p58.1 and p58.2 proteins. Furthermore, clinical features and laboratory data were compared between the anti‐p58.1/58.2 antibody–positive and –negative patients.

Results

Anti‐p58.1 antibodies were detected in 7 (23.3%) of the 30 patients with SLE, 9 (30%) of the 30 patients with RA, and 6 (27.3%) of the 22 patients with Behçet's disease. Anti‐p58.2 antibodies were detected in the same 22 patients who were positive for the anti‐p58.1 antibodies. None of the serum samples from the healthy donors were positive for antibodies to the recombinant p58.1 or p58.2 molecules. Compared with the anti‐p58.1/58.2 antibody–negative patients, the anti‐p58.1/58.2 antibody–positive patients had significantly elevated levels of serum IgG in all 3 diseases tested, an accelerated erythrocyte sedimentation rate in RA and SLE, and decreased white blood cell counts in RA.

Conclusion

This report is the first to describe the presence of autoantibodies to KIR2DL (p58.1 and p58.2) in the sera of patients with systemic autoimmune diseases. Considering the correlation with several clinical features, these autoantibodies may be involved in the pathologic process of the autoimmune diseases.

     

Association of killer cell immunoglobulin-like receptors with scleroderma

OBJECTIVE: Scleroderma is an autoimmune disorder of unknown etiology. A genetic contribution has been demonstrated, and genes influencing activation of the immune system have been potentially identified as candidate genes in this process. The repertoire of killer cell immunoglobulin-like receptors (KIRs) that are involved in the activation of T cells and natural killer cells is highly variable. Recently, an association of KIR2DS2 with vasculitis in patients with rheumatoid arthritis has been reported. Because scleroderma is characterized by an involvement of the vascular system, we sought to determine whether KIR2DS2 is associated with scleroderma. METHODS: We typed 9 KIR genes in 102 patients with scleroderma and in 100 blood donors, using polymerase chain reaction on genomic DNA. RESULTS: Twelve patients with scleroderma, compared with only 2 blood donors, had KIR phenotypes characterized by the presence of the activating KIR2DS2 and the absence of the corresponding inactivating KIR2DL2 (P = 0.005). CONCLUSION: The genetic combination of KIR2DS2+ and KIR2DL2- is associated with scleroderma.     

Inhibitory killer cell immunoglobulin‐like receptor (iKIR) mismatches improve survival after T‐cell‐repleted haploidentical transplantation

Alloreactivity triggered by interaction between killer cell immunoglobulin‐like receptors (KIRs) and natural killer (NK) cells plays a role in the graft‐versus‐tumor effect after hematopoietic stem cell transplantation (SCT). Our aim in this study was to evaluate this role in the setting of T‐cell‐repleted haploidentical SCT with postinfusion high‐dose cyclophosphamide (PT‐Cy). We included 33 patients. Among patient–donor pairs with at least 1 inhibitory KIR (iKIR) gene mismatch, event‐free survival (EFS) and cumulative incidence of relapse 1 year after transplant were significantly better (85% vs. 37% [P = 0.008] and 18% vs. 46% [P = 0.041], respectively). A subanalysis in 12 patients with Hodgkin's lymphoma (HL) showed an improvement in EFS 1 year after transplant in those patients with KIR ligand mismatch (100% vs. 25%, P = 0.012), although overall survival (OS) was not affected (85% vs. 80%, P = 0.2). Eight of 12 patient–donors pairs presented iKIR mismatches. Of note, this outcome was better in the small subgroup, both for EFS (100% vs. 25%, P = 0.012) and for OS (100% vs. 37%, P = 0.004). Our data suggest that in the setting of T‐cell‐repleted haploidentical SCT with PT‐Cy, iKIR mismatch is associated with improved survival, with particularly good results for both iKIR and KIR ligand mismatches in patients with HL.     

Activating killer immunoglobulin‐like receptor incompatibilities enhance graft‐versus‐host disease and affect survival after allogeneic hematopoietic stem cell transplantation

Objectives: Killer immunoglobulin‐like receptors (KIRs) regulate function of natural killer (NK) cells and a subset of T cells. In this study, we prospectively evaluated the impact of donor and recipient activating KIR genes on outcome of allogeneic hematopoietic stem cell transplantation (alloHSCT) for patients with hematological malignancies. Methods: One‐hundred consecutive recipients of myeloablative transplantation and their donors were tested for KIR genotype as well as for immune reconstitution, including activating KIR expression on NK cells and T cells. Results: In a multivariate analysis, mismatches of particular activating KIRs such that the patient was negative and the donor was positive (P^?D⁺) resulted in increased risk of acute (KIR2DS1) and chronic (KIR2DS3) graft‐versus‐host disease (GVHD) as well as relapse (KIR2DS5). KIR2DS1 incompatibility in the same direction in the presence of HLA‐C‐group 2 ligand in recipient was associated with reduced overall (risk ratio, RR = 3.01; P = 0.01) and disease‐free survival (RR = 2.92, P = 0.03). Activating mismatches in P^?D⁺ direction resulted in decreased CD4⁺ : CD8⁺ T‐cell ratio up to 1 yr after alloHSCT, as a consequence of decreased CD3⁺CD4⁺ number within the first 100 d and increased CD3⁺CD8⁺ number in later time‐points. Among six evaluated patients, expression of activating KIRs on NK cells and T cells was particularly prominent for those developing intestinal GVHD. Conclusion: Our findings indicate that the presence of particular activating KIRs in donor with their absence in recipient enhances GVHD, which is not accompanied by graft‐versus‐leukemia effect. Evaluation of activating KIR genotype may allow optimization of both donor selection and transplantation procedure in order to avoid GVHD.     

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 arthritis with a gene complex encoding C‐type lectin–like receptors

Objective

To identify susceptibility genes in a rat model of rheumatoid arthritis (RA) and to determine whether the corresponding human genes are associated with RA.

Methods

Genes influencing oil‐induced arthritis (OIA) were position mapped by comparing the susceptibility of inbred DA rats with that of DA rats carrying alleles derived from the arthritis‐resistant PVG strain in chromosomal fragments overlapping the quantitative trait locus Oia2. Sequencing of gene complementary DNA (cDNA) and analysis of gene messenger RNA (mRNA) expression were performed to attempt to clone a causal gene. Associations with human RA were evaluated by genotyping single‐nucleotide polymorphisms (SNPs) in the corresponding human genes and by analyzing frequencies of alleles and haplotypes in RA patients and age‐, sex‐, and area‐matched healthy control subjects.

Results

Congenic DA rats were resistant to OIA when they carried PVG alleles for the antigen‐presenting lectin‐like receptor gene complex (APLEC), which encodes immunoregulatory C‐type lectin–like receptors. Multiple differences in cDNA sequence and mRNA expression precluded cloning of a single causal gene. Five corresponding human APLEC genes were identified and targeted. The SNP rs1133104 in the dendritic cell immunoreceptor gene (DCIR), and a haplotype including that marker and 4 other SNPs in DCIR and its vicinity showed an indication of allelic association with susceptibility to RA in patients who were negative for antibodies to cyclic citrullinated peptide (anti‐CCP), with respective odds ratios of 1.27 (95% confidence interval [95% CI] 1.06–1.52; uncorrected P = 0.0073) and 1.37 (95% CI 1.12–1.67; uncorrected P = 0.0019). Results of permutation testing supported this association of the haplotype with RA.

Conclusion

Rat APLEC is associated with susceptibility to polyarthritis, and human APLEC and DCIR may be associated with susceptibility to anti‐CCP–negative RA.

     

杀伤细胞免疫球蛋白样受体基因多态性与白塞病的关联性分析

目的探讨杀伤细胞免疫球蛋白样受体(KIR)基因多态性与白塞病(BD)发生是否存在关联。方法采用聚合酶链反应(PCR)／序列特异性引物(SSP)方法调查上海地区汉族95例白塞病患者和87名正常对照KIR基因位点的多态性。结果白塞病例组中KIR3DL1基因的频率(0．728)比对照组 (1．00)显著降低(RR=0．067,P=0．009);而其他各KIR基因频率与对照组相比差异无统计学意义。KIR单倍型频率、基因型频率与对照组相比差异也无统计学意义。结论上海地区汉族白塞病的发生可能与 KIR3DL1基因之间呈负相关。     

Subjects with chronic lymphocytic leukaemia‐like B‐cell clones with stereotyped B‐cell receptors frequently show MDS‐associated phenotypes on myeloid cells

An increasing body of evidence suggests the potential occurrence of antigen encounter by the cell of origin in chronic lymphocytic leukaemia (CLL) and CLL‐like monoclonal B‐cell lymphocytosis (MBL). However, the scenario in which this event might occur remains unknown. In order to gain insight into this scenario we investigated the molecular, cytogenetic and haematological features of 223 CLL‐like (n = 84) and CLL (n = 139) clones with stereotyped (n = 32) versus non‐stereotyped (n = 191) immunoglobulin heavy chain variable region (IGHV) amino acid sequences. Overall, stereotyped CLL‐like MBL and CLL clones showed a unique IGHV profile, associated with higher IGHV1 and lower IGHV3 gene family usage (P = 0·03), longer IGHV complementary determining region 3 (HCDR3) sequences (P = 0·007) and unmutated IGHV (P < 0·001) versus non‐stereotyped clones. Whilst the overall size of the stereotyped B‐cell clones in peripheral blood did not appear to be associated with the CLL‐related cytogenetic profile of B‐cells (P > 0·05), it did show a significant association with the presence of myelodysplastic syndrome (MDS)‐associated immunophenotypes on peripheral blood neutrophils and/or monocytes (P = 0·01). Altogether our results point to the potential involvement of different selection forces in the expansion of stereotyped vs. non‐stereotyped CLL and CLL‐like MBL clones, the former being potentially favoured by an underlying altered haematopoiesis.     

Association of killer cell immunoglobulin-like receptor genotypes with microscopic polyangiitis

OBJECTIVE: Genetic background and infection have been implicated in the etiology of microscopic polyangiitis (MPA). Killer cell immunoglobulin-like receptors (KIRs) are a diverse family of activating and inhibitory receptors expressed on natural killer (NK) cells and T cells, the genes of which show extreme polymorphism. Some KIRs bind to HLA class I subgroups, and genetic interactions between KIR genes and their ligand HLA have been shown to be associated with several autoimmune and viral diseases. In this study, we examined possible associations of the presence or absence of KIR loci with a genetic predisposition to MPA. METHODS: The presence or absence of 14 KIR loci was determined in 57 myeloperoxidase antineutrophil cytoplasmic antibody-positive Japanese subjects (43 patients with MPA and 239 healthy controls). RESULTS: The carrier frequency of activating KIR2DS3 was significantly decreased among patients with MPA compared with healthy controls (4.7% versus 16.7%; P = 0.038, odds ratio [OR] 0.24, 95% confidence interval [95% CI] 0.06-0.94). When KIRs were analyzed in combination with their HLA ligands, the proportion of individuals carrying inhibitory KIR3DL1 and HLA-Bw4 but not activating receptor KIR3DS1, a combination presumed to be the most inhibitory of all KIR3DS1/3DL1/HLA-B combinations, was significantly increased in the MPA group compared with the control group (46.5% versus 27.0%; P = 0.014, OR 2.35, 95% CI 1.18-4.70). Furthermore, when subjects were classified according to KIR3DL1/3DS1/HLA-B and KIR2DL1/ HLA-C combinations, an increasing trend toward susceptibility was observed as combinations became more inhibitory. CONCLUSION: The decreased activation potential of NK and/or T cells associated with KIR/HLA genotypes may predispose to MPA, possibly through insufficient resistance against infections.     

杀伤细胞免疫球蛋白样受体基因多态性与血清阴性脊柱关节病的关联性研究

目的 探讨杀伤细胞免疫球蛋白样受体(KIR)基因多态性与血清阴性脊柱关节病(SpA)的发生是否存在关联。方法 采用聚合酶链反应(PCR)／系列特异性引物(SSP)方法，调查上海地区197例HLA—B27( )SpA患者和87名种族匹配的正常对照KIR基因位点的多态性。结果 SpA病例组中KIR3DLl基因的频率(0．763)比对照组(1．00)显著降低(RR=0．76，P=0．003)，两个假基因KIR2DRI和KIR3DPI的频率较对照组明显升高(RR=1．1，P=0．004)，而其他各KIR基因频率差异无显著性。结论 KIR3DL1基因与SpA的发生可能存在负相关。