Analysis of Helios gene expression and Foxp3 TSDR methylation in the newly diagnosed Rheumatoid Arthritis patients

Background: The control of auto-reactive cells is defective in rheumatoid arthritis (RA). Regulatory T (Treg) cells which play a key role in the modulation of immune responses have an impaired function in RA. Foxp3 is a master regulator of Treg cells which its expression is under the tight control of epigenetic mechanisms. In the current study, we analyzed the epigenetic modulation of the Foxp3 Treg-specific demethylated region (TSDR) and Helios gene expression to determine Treg cells alteration in RA patients.

Methods: We have recruited 20 newly diagnosed patients with RA and 41 healthy controls in our study. The measurement of Foxp3 and Helios gene expression was performed by the real-time PCR technique and the methylation level of TSDR was analyzed by bisulfite treatment and quantitative methylation-specific PCR (Q-MSP).

Results: We found that RA patients had significantly lower level of Foxp3 gene expression and TSDR demethylation compared to healthy subjects (P < 0.001 and P = 0.006, respectively). Inversely, the Helios gene expression was elevated significantly in RA patients group (P = 0.048). We also observed a significant correlation between Foxp3 and Helios gene expression (P = 0.016) as well as a significant correlation between FoxP3 expression and demethylation rate of TSDR (P = 0.010).

Conclusion: Our results suggested that both epigenetic modifications and Helios gene expression may have important roles in the pathogenesis of RA through their effects on Foxp3 gene expression.     

Peripheral whole blood FOXP3 TSDR methylation: a potential marker in severity assessment of autoimmune diseases and chronic infections

Immune dysregulation is a cardinal feature of autoimmune diseases and chronic microbial infections. In particular, regulatory T cells are downregulated in autoimmune diseases while upregulated in chronic microbial infections. FOXP3 is the master regulator of Treg development. Treg-specific demethylated region (TSDR) is a highly conserved locus on the FOXP3 gene that is fully demethylated in natural Tregs but methylated in effector T cells. In our study, we used high resolution melt-polymerase chain reaction (HRM-PCR) to determine the FOXP3 TSDR methylation status in autoimmune diseases and chronic microbial infections. We found that FOXP3 TSDR to have the highest mean melting temperature (highly methylated) in active SLE patients compared to all the other groups (p?<?0.001). The psoriasis group also had a significantly high mean melting temperature (78.62?±?0.20) when compared with the inactive SLE group (78.49?±?0.29, p?<?0.05) and control group (78.44?±?0.25, p?<?0.01). There was no significant difference in melting temperature between inactive SLE and healthy controls. Disease activity in SLE was directly associated with methylation of the FOXP3 TSDR. On the other hand, patients with chronic microbial infections had significantly lower FOXP3 TSDR mean melting temperature (demethylated) when compared with healthy controls (78.28?±?0.21 vs 78.44?±?0.25, p?<?0.05). Our results suggest that the use of HRM-PCR to detect FOXP3 TSDR methylation status is a reliable and easy method to predict natural regulatory T cell levels in peripheral blood in different disease conditions. Determining FOXP3 TSDR methylation status can be a useful tool in diagnosis, and monitoring the severity of autoimmune diseases and chronic microbial infections.     

CD98-induced CD147 signaling stabilizes the Foxp3 protein to maintain tissue homeostasis

Regulatory T cell (Treg) stability is necessary for the proper control of immune activity and tissue homeostasis. However, it remains unclear whether Treg stability must be continually reinforced or is established during development under physiological conditions. Foxp3 has been characterized as a central mediator of the genetic program that governs Treg stability. Here, we demonstrate that to maintain Foxp3 protein expression, Tregs require cell-to-cell contact, which is mediated by the CD147-CD98 interaction. As Tregs are produced, CD147, which is expressed on their surface, is stimulated by CD98, which is widely expressed in the physiological environment. As a result, CD147’s intracellular domain binds to CDK2 and retains it near the membrane, leading to Foxp3 dephosphorylation and the prevention of Foxp3 degradation. In addition, the optimal distribution of Foxp3+ Tregs under both pathological and physiological conditions depends on CD98 expression. Thus, our study provides direct evidence that Foxp3-dependent Treg stability is reinforced in the periphery by the interaction between CD147 and CD98 in the surrounding environment. More importantly, Tregs with high CD147 expression effectively inhibit inflammatory responses and maintain Foxp3 stability, which has guiding significance for the application of Tregs in immunotherapy.     

急性期川崎病Foxp3基因甲基化改变及意义初探

目的 探讨急性期川崎病(KD)Foxp3基因甲基化状态及其在KD免疫发病机制中的作用.方法 急性期KD患儿30例,正常同年龄对照组18例,KD患儿分别于静脉丙种球蛋白(IVIG)治疗前后直接取血备检.甲基化特异性定量PCR(MSQP)检测CD4+T细胞Foxp3基因启动子、调节性T细胞(Tr)特异性甲基化区(TSDR)CpG岛甲基化状态;流式细胞术检测外周血CD4+CD25+Foxp3+Tr的比例;荧光定量PCR检测CD4+T细胞Foxp3、CTLA4、GITR、LAG3、CCR8、UBD、LGALS3等基因mRNA表达.结果 (1)急性期KD患儿CD4+T细胞Foxp3基因启动子CpG岛非甲基化水平明显低于同年龄对照组(P＜0.01),经IVIG治疗后明显升高(P＜0.01);TSDR区CpG岛非甲基化水平各组间差异无统计学意义(P＞0.05);(2)急性期KD患儿CD4+CD25+Foxp3+Tr细胞比例及CD4+T细胞Foxp3 mRNA表达水平明显低于正常对照组(P＜0.01),且与Foxp3基因启动子CpG岛非甲基化水平呈正相关(CD4+CD25+Foxp3+Tr:r=0.76,P＜0.01;Foxp3:r=0.89,P＜0.01),IVIG治疗后显著上升(P＜0.01);(3)急性期KD患儿CD4+CD25+Foxp3+Tr细胞相关因子CTLA4、GITR、LAG3和CCR8等基因mRNA水平显著降低(P＜0.01),IVIG治疗后均有不同程度的恢复(P＜0.01);Foxp3依赖性分子UBD和LGALS3表达水平亦低于正常对照组(P＜0.01),IVIG治疗后基本恢复至正常水平(P＜0.01).结论 急性期KD患儿Foxp3基因启动子非甲基化水平低下可能与KD免疫调节功能紊乱有关.     

CD8+ Foxp3+ T cells share developmental and phenotypic features with classical CD4+ Foxp3+ regulatory T cells but lack potent suppressive activity

"Suppressor T cells" were historically defined within the CD8(+) T-cell compartment and recent studies have highlighted several naturally occurring CD8(+) Foxp3(-) Treg populations. However, the relevance of CD8(+) Foxp3(+) T cells, which represent a minor population in both thymi and secondary lymphoid organs of nonmanipulated mice, remains unclear. We here demonstrate that de novo Foxp3 induction in peripheral CD8(+) Foxp3(-) T cells is counter-regulated by DC-mediated co-stimulation via CD80/CD86. CD8(+) Foxp3(+) T cells fail to develop in TCR-transgenic mice with Rag1(-/-) background, similar to classical CD4(+) Foxp3(+) Tregs. Notably, both naturally occurring and induced CD8(+) Foxp3(+) T cells express bona fide Treg markers including CD25, GITR, CTLA4 and CD103, and show defective IFN-γ production upon restimulation when compared with their CD8(+) Foxp3(-) counterparts. However, utilizing DEREG transgenic mice for the isolation of Foxp3(+) cells by eGFP reporter expression, we demonstrate that induced CD8(+) Foxp3(+) T cells similar to activated CD8(+) Foxp3(-) T cells only mildly suppress T-cell proliferation and IFN-γ production. We therefore categorize CD8(+) Foxp3(+) T cells as a tightly controlled population sharing certain developmental and phenotypic properties with classical CD4(+) Foxp3(+) Tregs, but lacking potent suppressive activity.