Genetic variations in the KIR gene family may contribute to susceptibility to ankylosing spondylitis: a meta-analysis

Non-classical human leucocyte antigens in ankylosing spondylitis: possible association with HLA-E and HLA-F

OBJECTIVES

Ankylosing spondylitis (AS) is the most prevalent form of spondyloarthritis, with a known genetic association with the HLA-B27 molecule. The aim of this study was to assess the contribution of the HLA-G, HLA-E and HLA-F to AS susceptibility/protection in Portuguese patients with HLA-B27 AS and HLA-B27 unaffected controls.

METHODS

High-resolution typing of HLA-G, HLA-E and HLA-F was performed in 228 patients with HLA-B27 AS and 244 HLA-B27 unaffected controls. Allelic, genotypic and haplotypic frequencies were compared between cohorts. To replicate the results, single nucleotide polymorphisms (SNPs) in HLA-E and HLA-F genes were typed in Australian cohorts. For further confirmation, a group of European-descent patients with AS and unaffected controls were genotyped for Major Histocompatibility Complex SNPs using the Illumina microarray.

RESULTS

In the Portuguese population, no significant differences were found in HLA-G. For HLA-E, a significant difference was detected for the genotype HLA-E*01:01:01/01:03:01 (p=0.009; pc=0.009; OR=0.51), with a protection effect. For HLA-F, significant differences were detected in the allele HLA-F*01:01:02 (p=0.0049; pc=0.0098; OR=0.60) and corresponding SNP rs2075682 (p=0.0004; pc=0.0008; OR=0.53), suggesting protection and in the genotype HLA-F*01:01:01/01:03:01 (p=0.011; pc=0.043; OR=2.00), suggesting a susceptibility effect. Three G-E-F haplotypes with significant differences were detected but occur in a very small number of individuals. The only significant differences detected in the replication studies were for HLA-E rs1059510 in the Australians and for HLA-F rs1736924 in the European-descent cohorts.

CONCLUSION

Our results reveal suggestive AS protective and susceptibility effects from both HLA-E and HLA-F loci, however with population differences. To our knowledge, this is the first study showing association of HLA-F with AS.

Association between killer cell immunoglobulin-like receptor (KIR) polymorphisms and systemic lupus erythematosus (SLE) in populations: A PRISMA-compliant meta-analysis

BACKGROUND

Recently, a growing number of studies show that the killer cell immunoglobulin-like receptor (KIR) gene polymorphisms may play a role in the systemic lupus erythematosus (SLE) susceptibility. Nonetheless, the results were inconsistent. Thus, a meta-analysis was carried out by integrating multiple research to clarify the association between KIR polymorphisms and SLE susceptibility.

METHODS

The Web of Science, Embase (Ovid), PubMed, Elsevier Science Direct, the Chinese Biomedical Database and CNKI, Wanfang databases (last search was updated on May 15, 2016) were systematically searched to select studies on addressing the association between the KIR polymorphisms and susceptibility to SLE in populations. The odds ratio (OR) with 95% confidence interval (95% CI) was calculated.

RESULTS

A total of 10 published case-control studies involving 1450 SLE patients and 1758 controls were available for this meta-analysis. Results suggested that KIR2DL1 might be a risk factor for SLE (OR 2DL1 =1.047, 95% CI=1.011-1.083) in all subjects. The KIR2DL3, KIR2DL5 were identified as protective factors for SLE in Asian populations (OR2DL3= 0.215, 95% CI = 0.077-0.598; OR2DL5 = 0.588, 95% CI = 0.393-0.881), but not in Caucasians.

CONCLUSIONS

The meta-analysis results suggested that 2DL1 might be a potential risk factor and 2DL3, 2DL5 might be protective factors for SLE in Asians but not in Caucasians.

Activating killer immunoglobulin-like receptors genes are associated with increased susceptibility to ankylosing spondylitis

The aim of this study was to analyse the association of specific killer cell immunoglobulin-like receptors (KIR) genes and haplotypes with susceptibility to ankylosing spondylitis (AS) and its different clinical manifestations in a Spanish population. The presence or absence of all KIR genes was studied for their association with AS. A total of 176 patients with AS and 435 healthy control subjects were selected for this study based on clinical criteria. The commercial KIR-sequence-specific oligonucleotides (SSO) typing kit was used to investigate KIR typing. Frequencies of KIR2DS1 and KIR3DS1 genes were increased significantly in patients compared with healthy controls [52·8 versus 38·2%, PBonf < 0·01, odds ratio (OR) = 1·81 (1·28-2·59); 51·7 versus 37·5%, PBonf < 0·01, OR = 1·79 (1·25-2·54)]. Moreover, the frequency of activating genotypes in the AS patient group was significantly higher than in the healthy control group (P < 0·05). KIR2DS1 and KIR3DS1, in addition to human leucocyte antigen (HLA)-B27, may play an important role in the pathogenesis of AS. However, we show that the contribution of the KIR genes to AS susceptibility extends beyond the association with individual KIRs, with an imbalance between activating and inhibitory KIR genes seeming to influence the susceptibility to AS.