FCGR3A V(176) polymorphism for systemic lupus erythematosus susceptibility in Mexican population

Immune-relevant genes of systemic lupus erythematosus by transcriptome profiling analysis

OBJECTIVE

Our study aimed to reveal the roles of long noncoding RNA (lncRNA) and immune-relevant genes in systemic lupus erythematosus (SLE).

METHODS

Expression profiling dataset GSE65391 consisted of 72 healthy blood samples and 924 SLE blood samples was downloaded from the Gene Expression Omnibus. Differentially expressed RNAs (DERs) in SLE samples were identified using the Limma package. Immune-relevant DERs were uncovered after assessing the immune cell infiltration types of different samples. Modules significantly related to the disease were extracted via weighted gene co-expression network analysis (WGCNA), followed by module-trait analysis. LncRNA-mRNA co-expression network was constructed for DERs in immune-relevant modules. Genes related to SLE were further revealed via the Comparative Toxicogenomics Database (CTD). Validation assay was conducted by another independent expression profiling dataset, GSE46907 (consisted of 5 healthy blood samples and 5 SLE blood samples) and quantitative reverse transcription-polymerase chain reaction (qRT-PCR) analysis of 15 healthy blood samples and 15 SLE blood samples.

RESULTS

A total of 606 DERs, including 19 lncRNAs and 587 mRNAs, were identified. Obvious differences were observed in the proportions of 20 immune cell types, and 378 immune-relevant DERs were revealed. Genes in the lncRNA-mRNA co-expression network were significantly enriched in primary immunodeficiency, hematopoietic cell lineage, B cell receptor signaling pathway, SLE (up-regulated FCGR3A, down-regulated CD40LG, up-regulated HIST1H2BE, down-regulated human leukocyte antigen [HLA]-DOA, down-regulated HLA-DOB, up-regulated HIST1H3D, and up-regulated HIST1H2BC), and intestinal immune network for IgA production. SLE-related gene, CD40LG, retrieved from CTD has co-expression interactions with seven differentially expressed lncRNAs (HCG27, LINC02555, LINC02210, DHRS4-AS1, MIR600HG, DANCR, and LINC01278). CD40LG and HLA-DOA, were observed down-regulated, and FCGR3A, and HIST1H2BE were up-regulated in validation dataset GES46907. Moreover, CD40LG was validated to be down-regulated using qRT-PCR.

CONCLUSIONS

Our results provide new insight in understanding the pathogenesis of SLE and might be helpful for developing new therapeutic approaches of SLE by modulating immune response.

The FcγRIIIA-158 VV genotype increased the risk of post-transplant lymphoproliferative disorder in T-cell-depleted kidney transplant recipients - a retrospective study

Post-transplantation lymphoproliferative disorder (PTLD) is a severe complication in organ transplant recipients. The use of T lymphocyte-depleting antibodies (TLDAb), especially rabbit TLDAb, contributes to PTLD, and the V158F polymorphism of Fc gamma receptor IIIA (FcγRIIIA) also named CD16A could affect the concentration-effect relationship of TLDAb. We therefore investigated the association of this polymorphism with PTLD in kidney transplant recipients. We characterized the V158F polymorphism in two case-control cohorts (discovery, n = 196; validation, n = 222). Then, we evaluated the binding of rabbit IgG to human FcγRIIIA-158V and FcγRIIIA-158F. The V158F polymorphism was not linked to PTLD in the overall cohorts, but risk of PTLD was increased in VV homozygous recipients receiving TLDAb compared with F carriers in both cohorts, especially in recipients receiving TLDAb without muromonab (discovery: HR = 2.22 [1.03-4.76], P = 0.043, validation: HR = 1.75 [1.01-3.13], P = 0.049). In vitro, we found that the binding of rabbit IgG to human NK-cell FcγRIIIA was increased when cells expressed the 158-V versus the 158-F allotype. While the 158-V allotype of human FcγRIIIA binds rabbit immunoglobulin-G with higher affinity, the risk of PTLD was increased in homozygous VV kidney transplant recipients receiving polyclonal TLDAb.

Fc gamma receptor IIIa polymorphism is not associated with susceptibility to systemic lupus erythematosus in Brazilian patients

We evaluated the possible association between FCGR3A V/F (158) polymorphism and SLE susceptibility and clinical phenotype in 305 sequentially retrieved SLE patients and 300 healthy controls from the southeastern part of Brazil by allele-specific polymerase chain reaction. Our results showed no association between FCGR3A 158V/F alleles and susceptibility to SLE in this series of patients albeit the heterozygous genotype was strongly associated with the disease.

Comprehensive Assessment of the Association between FCGRs polymorphisms and the risk of systemic lupus erythematosus: Evidence from a Meta-Analysis

We performed a meta analysis to assess the relationship of FCGRs polymorphisms with the risk of SLE. Thirty-five articles (including up to 5741 cases and 6530 controls) were recruited for meta-analysis. The strongest association was observed between FCGR2B rs1050501 and SLE under the recessive genotypic model of C allele in the overall population (CC vs CT/TT, OR = 1.754, 95%CI: 1.422–2.165, P = 1.61 × 10⁻⁷) and in Asian population (CC vs CT/TT, OR = 1.784, 95%CI; 1.408–2.261, P = 1.67 × 10⁻⁶). We also found that FCGR3A rs396991 were significant association with the susceptibility to SLE in overall population in recessive model of T allele (TT vs TG/GG, OR = 1.263, 95%CI: 1.123–1.421, P = 9.62 × 10⁻⁵). The results also showed that significant association between FCGR2A rs1801274 and SLE under the allelic model in the overall population (OR = 0.879 per A allele, 95%CI: 0.819–0.943, P = 3.31 × 10⁻⁴). The meta-analysis indicated that FCGR3B copy number polymorphism NA1·NA2 was modestly associated with SLE in overall population (OR = 0.851 per NA1, 95%CI: 0.772–0.938, P = 1.2 × 10⁻³). We concluded that FCGR2B rs1050501 C allele and FCGR3A rs396991 T allele might contribute to susceptibility and development of SLE, and were under recessive association model. While, FCGR2A rs1801274 A allele and FCGR3B NA1 were associated with SLE and reduced the risk of SLE.

Polymorphism of FCGR3A gene in sarcoidosis

We showed increased level of immune complexes (ICs) with mycobacterial heat shock proteins (Mtb-hsp) and increased expression of receptors for Fc fragment of immunoglobulin G (FcγR) I-III on blood monocytes with their increased phagocytic activity, responsible for clearance of these ICs in sarcoidosis (SA). Since FcγRIIIa is the most crucial in this process, we genotyped 77 SA patients and 143 healthy controls with polymerase chain reaction for V158F polymorphism of FCGR3A gene, encoding FcγRIIIa. We revealed significantly higher percentage of 158F and 158FF and lower of 158FV variants in Stage I of SA versus controls. Conversely, in Stage II of SA, we found increase in 158VV homozygotes versus controls. We also showed significant increase of 158F and 158FF variants in Stage I vs II and of 158V in Stage II vs I. Therefore, in Stage I, 158F allele may cause decreased FcγRIIIa affinity and clearance of ICs, whereas in Stage II, 158V allele may cause effective FcγRIIIa affinity to ICs with e.g. mycobacteria, their phagocytosis, Mtb-hsp secretion with ICs formation, Mtb-hsp epitope spread and subsequent immune reaction. Thus, V158F polymorphism of FCGR3A may explain the immunocomplexemia in our patients and might serve as prognostic marker of clinical course of sarcoidosis.

Profiling of autoantibodies in IgA nephropathy, an integrative antibiomics approach

BACKGROUND AND OBJECTIVES

IgG commonly co-exists with IgA in the glomerular mesangium of patients with IgA nephropathy (IgAN) with unclear clinical relevance. Autoantibody (autoAb) biomarkers to detect and track progression of IgAN are an unmet clinical need. The objective of the study was to identify IgA-specific autoAbs specific to IgAN.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

High-density protein microarrays were evaluated IgG autoAbs in the serum of IgAN patients (n = 22) and controls (n = 10). Clinical parameters, including annual GFR and urine protein measurements, were collected on all patients over 5 years. Bioinformatic data analysis was performed to select targets for further validation by immunohistochemistry (IHC).

RESULTS

One hundred seventeen (1.4%) specific antibodies were increased in IgAN. Among the most significant were the autoAb to the Ig family of proteins. IgAN-specific autoAbs (approximately 50%) were mounted against proteins predominantly expressed in glomeruli and tubules, and selected candidates were verified by IHC. Receiver operating characteristic analysis of our study demonstrated that IgG autoAb levels (matriline 2, ubiquitin-conjugating enzyme E2W, DEAD box protein, and protein kinase D1) might be used in combination with 24-hour proteinuria to improve prediction of the progression of IgAN (area under the curve = 0.86, P = 0.02).

CONCLUSIONS

IgAN is associated with elevated IgG autoAbs to multiple proteins in the kidney. This first analysis of the repertoire of autoAbs in IgAN identifies novel, immunogenic protein targets that are highly expressed in the kidney glomerulus and tubules that may bear relevance in the pathogenesis and progression of IgAN.