Association of the CD11b rs1143679 polymorphism with systemic lupus erythematosus in the Han Chinese population

Novel polymorphism of IFI44L associated with the susceptibility and clinical characteristics of systemic lupus erythematosus in a Chinese population

BACKGROUND

Interferon-inducible 44 like (IFI44L) is a newly discovered gene which has been reported to associate with the susceptibility of some infectious diseases, but there is no data on IFI44L SNP polymorphism associated with Systemic lupus erythematosus (SLE). In this study, we aimed to evaluate the association of IFI44L rs273259 polymorphism with the susceptibility and clinical characteristics of SLE in a Chinese population.

METHODS

576 SLE patients and 600 controls were recruited in this case-control study. Blood DNA was extracted and IFI44L rs273259 polymorphism was detected by TaqMan SNP Genotyping Assay Kit. The expression levels of IFI44L in Peripheral blood mononuclear cells were detected by RT-qPCR. The DNA methylation levels of IFI44L promoter were detected by bisulfite pyrosequencing.

RESULTS

The genotype and allele frequencies of IFI44L rs273259 in SLE patients have a significantly difference compared to healthy controls (P < 0.001). The genotype AG (vs. AA: OR = 2.849; P < 0.001) and the allele G (vs. A: OR = 1.454; P < 0.001) were associated with increased susceptibility of SLE. IFI44L rs273259 polymorphism was associated with clinical characteristics of SLE including malar rash (P < 0.001), discoid rash (P < 0.001), lupus nephritis (P < 0.001) and anti-Smith antibodies (P < 0.001). The expression levels of IFI44L were most significantly increased in genotype AG than genotype AA and GG (P < 0.01). The DNA methylation levels of IFI44L promoter were most significantly decreased in genotype AG than genotype AA and GG (P < 0.01).

CONCLUSIONS

Our results indicate novel polymorphism of IFI44L rs273259 was associated with the susceptibility and clinical characteristics of SLE in the Chinese population.

Association between complement gene polymorphisms and systemic lupus erythematosus: a systematic review and meta-analysis

Complement dysfunction results in impaired ability in clearing apoptotic cell debris that may stimulate autoantibody production in systemic lupus erythematosus (SLE). Herein, we provided a comprehensive search to find and meta-analyze any complement gene polymorphisms associated with SLE. The ITGAM, C1q, and MBL gene polymorphisms were included in this meta-analysis to reveal the exact association with SLE risk. Electronic databases, including Scopus, PubMed, and Google Scholar, were searched to find studies investigating the ITGAM, C1q, and MBL gene polymorphisms and SLE risk in different populations. The pooled odds ratio (OR) and its corresponding 95% confidence interval (CI) were used to analyze the association between ITGAM, C1q, and MBL gene polymorphisms and susceptibility to SLE. According to inclusion criteria, a total of 24 studies, comprising 4 studies for C1QA rs292001, 5 studies for C1QA rs172378, 9 studies for ITGAM rs1143679, 8 studies for MBL rs1800450, 3 studies for MBL2 rs1800451, and 3 studies for MBL2 rs5030737, were included in the final meta-analysis. A significant positive association was found between rs1143679 and SLE risk, while rs1800451 significantly associated with decreased SLE susceptibility. In summary, ITGAM gene rs1143679 SNP and MBL gene rs1800451 SNP were positively and negatively associated with SLE risk, respectively.

Clinical features and expression of type I interferon-inducible genes in systemic lupus erythematosus patients harboring rs1143679 polymorphism in China: a single-center, retrospective study

OBJECTIVE

This case-control study aimed to analyze the clinical features and determine the expression of type I interferon-induced genes in systemic lupus erythematosus (SLE) patients harboring the CD11b rs1143679 single-nucleotide polymorphism (SNP) and elucidate whether it is involved in the relapses of SLE.

METHODS

One hundred twenty-five relatively inactive SLE patients with SLEDAI scores < 6, including 102 CD11b rs1143679 G allele patients as controls and 23 rs1143679 A allele carriers as cases, were enrolled from the SLE patient specimen bank in the Department of Rheumatology and Immunology. The sample set was retrospectively analyzed for differences in clinical features, and quantitative PCR and Western blot analyses were performed to evaluate the relative expression of type I interferon (IFN)-inducible genes.

RESULTS

The 24-h urinary protein levels in the case group were significantly elevated, and serum C3 levels were significantly reduced compared with those in the control group (P = 0.019 and P = 0.021, respectively). The relative mRNA levels of IFN-inducible genes IFIT1, IFIT4, and ISG15 in the case group were higher than that in the control group (P = 0.0257, 0.0344, and 0.0311, respectively) and matched with the Western blot results.

CONCLUSIONS

The relative expression of type I IFN-inducible genes in inactive SLE patients harboring the CD11b rs1143679 polymorphism was higher than that in other lupus patients. These findings suggest that the rs1143679 SNP can precipitate relapses in inactive SLE patients.

KEY POINTS

• The rs1143679 GA genotype was associated with SLE clinical features. • The rs1143679 GA genotype showed higher interferon-inducible gene expression relative to the GG genotype.

An update on genetic susceptibility in lupus nephritis

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by multiple system involvement and positive serum autoantibodies. Lupus nephritis (LN) is the most common and serious complication of SLE, and it is the main cause of death in patients with SLE. Abnormalities in the immune system lead to LN and involve a variety of cells (T cells, B cells, macrophages, NK cells, etc.), cytokines (interleukin, tumor necrosis factor α, etc.) and their related pathways. Previous studies have shown that the interactions of genetic, epigenetic and environmental factors contribute to the pathogenesis and development of LN. In recent years, one genome-wide association study (GWAS) and a number of gene association studies have explored the susceptibility genes of LN, including immunization-, inflammation-, adhesion- and other pathway-related genes. These genes participate in or suggest the pathogenesis and progression of LN. In this review, we summarize the genetic susceptibility of LN and discuss the possible mechanism underlying the susceptibility genes of LN.

β2 Integrins-Multi-Functional Leukocyte Receptors in Health and Disease

β2 integrins are heterodimeric surface receptors composed of a variable α (CD11a-CD11d) and a constant β (CD18) subunit and are specifically expressed by leukocytes. The α subunit defines the individual functional properties of the corresponding β2 integrin, but all β2 integrins show functional overlap. They mediate adhesion to other cells and to components of the extracellular matrix (ECM), orchestrate uptake of extracellular material like complement-opsonized pathogens, control cytoskeletal organization, and modulate cell signaling. This review aims to delineate the tremendous role of β2 integrins for immune functions as exemplified by the phenotype of LAD-I (leukocyte adhesion deficiency 1) patients that suffer from strong recurrent infections. These immune defects have been largely attributed to impaired migratory and phagocytic properties of polymorphonuclear granulocytes. The molecular base for this inherited disease is a functional impairment of β2 integrins due to mutations within the CD18 gene. LAD-I patients are also predisposed for autoimmune diseases. In agreement, polymorphisms within the CD11b gene have been associated with autoimmunity. Consequently, β2 integrins have received growing interest as targets in the treatment of autoimmune diseases. Moreover, β2 integrin activity on leukocytes has been implicated in tumor development.

ITGAM is a risk factor to systemic lupus erythematosus and possibly a protection factor to rheumatoid arthritis in patients from Mexico

Introduction

ITGAM has consistently been associated with susceptibility to systemic lupus erythematosus (SLE) in many ethnically diverse populations. However, in populations with higher Amerindian ancestry (like Yucatan) or highly admixed population (like Mexican), ITGAM has seldom been evaluated (except few studies where patients with childhood-onset SLE were included). In addition, ITGAM has seldom been evaluated in patients with rheumatoid arthritis (RA). Here, we evaluated whether four single nucleotide polymorphisms (SNPs), located within ITGAM, were associated with SLE and RA susceptibility in patients from Mexico.

Methods

Our study consisted of 1,462 individuals, which included 363 patients with SLE (292 from Central Mexico and 71 from Yucatan), and 621 healthy controls (504 from Central Mexico and 117 from Yucatan). Our study also included 478 patients with RA from Central Mexico. TaqMan assays were used to obtain the genotypes of the four SNPs: rs34572943 (G/A), rs1143679 (G/A), rs9888739 (C/T), and rs1143683 (C/T). We also verified the genotypes by Sanger sequencing. Fisher's exact test and permutation test were employed to evaluate the distribution of genotype, allele, and haplotype between patients and controls.

Results

Our data show that all four ITGAM SNPs are significantly associated with susceptibility to SLE using both genotypic and allelic association tests (corrected for multiple testing, but not for population stratification). A second study carried out in patients from Yucatan, a southeastern part of Mexico (with a high Amerindian ancestry), also replicated SLE association with all four SNPs, including the functional SNP, rs1143679 (OR = 24.6 and p = 9.3X10^-6). On the other hand, none of the four SNPs are significant in RA after multiple testing. Interestingly, the GACC haplotype, which carries the ITGAM rs1143679 (A) minor allele, showed an association with protection against RA (OR = 0.14 and p = 3.0x10^-4).

Conclusion

Our data displayed that ITGAM is a risk factor to SLE in individuals of Mexican population. Concurrently, a risk haplotype in ITGAM confers protection against RA.

An update on genetic susceptibility in lupus nephritis

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by multiple system involvement and positive serum autoantibodies. Lupus nephritis (LN) is the most common and serious complication of SLE, and it is the main cause of death in patients with SLE. Abnormalities in the immune system lead to LN and involve a variety of cells (T cells, B cells, macrophages, NK cells, etc.), cytokines (interleukin, tumor necrosis factor α, etc.) and their related pathways. Previous studies have shown that the interactions of genetic, epigenetic and environmental factors contribute to the pathogenesis and development of LN. In recent years, one genome-wide association study (GWAS) and a number of gene association studies have explored the susceptibility genes of LN, including immunization-, inflammation-, adhesion- and other pathway-related genes. These genes participate in or suggest the pathogenesis and progression of LN. In this review, we summarize the genetic susceptibility of LN and discuss the possible mechanism underlying the susceptibility genes of LN.