A novel epitope from CD22 regulates Th1 and Th17 cell function in systemic lupus erythematosus

Effects of Astragalus membranaceus on systemic lupus erythematosus in a mouse model of pregnancy

BACKGROUND

This study used astragalus membranaceus (AM) to treat systemic lupus erythematosus (SLE) model mice during pregnancy, aiming to explore the role of AM in Helper T cell 17 (Th17) differentiation and SLE during pregnancy.

METHODS

We used lipopolysaccharide to constructed the SLE mouse model. AM decoction given by intragastric administration lasted from the eighth week of the mouse age until the mouse was killed. We estimated the messenger RNA  levels of IL-17a and Rorc, counted the Th17 cell number and examined the levels of cytokines including interleukin (IL)-12, tumor necrosis factor α, interferon gamma, IL-17A in mouse serum. Periodic acid-Schiff staining and renal glomerular/tubulointerstitial (TI) score were used to evaluate the progression of lupus nephritis (LN).

RESULTS

AM treatment improved the conception rate and increased the number and average weight of fetuses in SLE mice. It significantly decreased the urinary albumin/creatinine ratios and reduced the glomerular scores and TI scores in the pregnant SLE mice. AM gavage significantly decreased the weight of spleen, mesenteric lymph node, total splenocytes and T cells, and the expression of proinflammatory factors. Furthermore, AM treatment reduced the ratio of Th17 cells and the expression levels of RORγt and IL-17A.

CONCLUSION

AM significantly improved pregnancy outcomes and inhibited lupus nephritis during pregnancy in SLE mice.

Metabolic Factors that Contribute to Lupus Pathogenesis

Systemic lupus erythematosus (SLE) is an autoimmune disease in which organ damage is mediated by pathogenic autoantibodies directed against nucleic acids and protein complexes. Studies in SLE patients and in mouse models of lupus have implicated virtually every cell type in the immune system in the induction or amplification of the autoimmune response as well as the promotion of an inflammatory environment that aggravates tissue injury. Here, we review the contribution of CD4+ T cells, B cells, and myeloid cells to lupus pathogenesis and then discuss alterations in the metabolism of these cells that may contribute to disease, given the recent advances in the field of immunometabolism.

Unmasking of CD22 Co-receptor on Germinal Center B-cells Occurs by Alternative Mechanisms in Mouse and Man

CD22 is an inhibitory B-cell co-receptor whose function is modulated by sialic acid (Sia)-bearing glycan ligands. Glycan remodeling in the germinal center (GC) alters CD22 ligands, with as yet no ascribed biological consequence. Here, we show in both mice and humans that loss of high affinity ligands on GC B-cells unmasks the binding site of CD22 relative to naive and memory B-cells, promoting recognition of trans ligands. The conserved modulation of CD22 ligands on GC B-cells is striking because high affinity glycan ligands of CD22 are species-specific. In both species, the high affinity ligand is based on the sequence Siaα2-6Galβ1-4GlcNAc, which terminates N-glycans. The human ligand has N-acetylneuraminic acid (Neu5Ac) as the sialic acid, and the high affinity ligand on naive B-cells contains 6-O-sulfate on the GlcNAc. On human GC B-cells, this sulfate modification is lost, giving rise to lower affinity CD22 ligands. Ligands of CD22 on naive murine B-cells do not contain the 6-O-sulfate modification. Instead, the high affinity ligand for mouse CD22 has N-glycolylneuraminic acid (Neu5Gc) as the sialic acid, which is replaced on GC B-cells with Neu5Ac. Human naive and memory B-cells express sulfated glycans as high affinity CD22 ligands, which are lost on GC B-cells. In mice, Neu5Gc-containing glycans serve as high affinity CD22 ligands that are replaced by Neu5Ac-containing glycans on GC B-cells. Our results demonstrate that loss of high affinity CD22 ligands on GC B-cells occurs in both mice and humans through alternative mechanisms, unmasking CD22 relative to naive and memory B-cells.

Downregulation of TIM-3 mRNA expression in peripheral blood mononuclear cells from patients with systemic lupus erythematosus

The T-cell immunoglobulin and mucin domain (TIM) family is associated with autoimmune diseases, but its expression level in the immune cells of systemic lupus erythematosus (SLE) patients is not known. The aim of this study was to investigate whether the expression of TIM-3 mRNA is associated with pathogenesis of SLE. Quantitative real-time reverse transcription-polymerase chain reaction analysis (qRT-PCR) was used to determine TIM-1, TIM-3, and TIM-4 mRNA expression in peripheral blood mononuclear cells (PBMCs) from 132 patients with SLE and 62 healthy controls. The PBMC surface protein expression of TIMs in PBMCs from 20 SLE patients and 15 healthy controls was assayed by flow cytometry. Only TIM-3 mRNA expression decreased significantly in SLE patients compared with healthy controls (P<0.001). No significant differences in TIM family protein expression were observed in leukocytes from SLE patients and healthy controls (P>0.05). SLE patients with lupus nephritis (LN) had a significantly lower expression of TIM-3 mRNA than those without LN (P=0.001). There was no significant difference in the expression of TIM-3 mRNA within different classes of LN (P>0.05). Correlation of TIM-3 mRNA expression with serum IgA was highly significant (r=0.425, P=0.004), but was weakly correlated with total serum protein (r_s=0.283, P=0.049) and serum albumin (r_s=0.297, P=0.047). TIM-3 mRNA expression was weakly correlated with the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI; r_s=-0.272, P=0.032). Our results suggest that below-normal expression of TIM-3 mRNA in PBMC may be involved in the pathogenesis of SLE.

Fragments of truth: T-cell targets of polyclonal immunoglobulins in autoimmune diseases

The expanding therapeutic use of high-dose intravenous immunoglobulin (IVIg) in autoimmune diseases has raised important practical and conceptual issues over the last few years. These have prompted a number of research efforts aimed at characterizing aspects of the mechanism of action of current IVIg preparations, which might lead to the development of standardized, more cost-effective agents. Although polyclonal IgG in these preparations are mostly thought to act via direct interference with disease-specific, pathogenic autoantibodies, evidence from clinical and experimental work points to the involvement of crucial checkpoints upstream of self-reactive B-cell activation and autoantibody production. Reviewed herein are the results of the most recent studies documenting the crucial role of regulatory T cells (Treg) in the immunomodulatory activity of IVIg, and the molecular mechanisms mediating the effect of specific IgG fragments and glycoforms on Treg activity and the ensuing downregulation of T-cell effector responses of different sign and magnitude. Further progress in this area of translational research may lead to the development of innovative strategies aimed at restoring tolerance in autoimmune diseases.

Association of a TNIP1 polymorphism with Vogt-Koyanagi-Harada syndrome but not with ocular Behcet's disease in Han Chinese

Objectives

The aim of the study was to investigate the association of TNFα-induced protein 3 interacting with protein 1 (TNIP1) gene polymorphisms with Vogt–Koyanagi–Harada (VKH) syndrome and Behcet’s disease (BD) in a Han Chinese population.

Methods

A total of 656 BD patients, 961 VKH syndrome patients and 1534 healthy controls were included in this two-stage case control study. Seven SNPs, including rs17728338, rs7708392, rs10036748, rs3762999, rs999556, rs4958881 and rs3792783, belonging to TNIP1 were genotyped and analyzed by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. The data were analyzed by using the χ2 or Fisher's exact test and corrected for multiple comparisons by the Bonferroni method.

Results

A significantly increased frequency of the GG genotype and a decreased frequency of the AG genotype of rs17728338 were found in VKH patients (Pc = 0.038 OR = 1.934, 95% CI  = 1.438∼2.601). No significant difference was noted in allele or genotype frequencies of rs7708392, rs10036748, rs3762999, rs999556, rs4958881 and rs3792783, between VKH patients and healthy controls (Pc>0.05). No significant difference was noted in allele or genotype frequencies of the tested 7 SNPs between BD patients and healthy controls. Analysis of extraocular clinical findings, did not reveal an association of the TNIP1 gene polymorphisms with BD or VKH syndrome subgroups.

Conclusion

A TNIP1 polymorphism may be a risk factor for VKH syndrome in Han Chinese.