Efficacy and safety of low-dose Interleukin-2 in the treatment of moderate to severe bullous pemphigoid: a single center perspective-controlled trial.

BACKGROUND: Regulatory T cells (Tregs) are reduced in the peripheral blood and skin lesions of bullous pemphigoid (BP) patients. Low-dose IL-2 therapy can stimulate Tregs specifically, suggesting potential for the treatment of BP. OBJECTIVE: To evaluate the response to low-dose IL-2 therapy in the treatment of moderate to severe BP. METHODS: 43 patients with moderate to severe BP were included. The therapy included systemic corticosteroids with initial dose of 0.5mg/kg/d for moderate and 1.0mg/kg/d for severe disease respectively, combined with allowed immunosuppressants for control group, while in addition to the same corticosteroids therapy, IL-2 (half million IU) was administered subcutaneously every other day for treatment group for 8 weeks. The primary outcome was the number of days required to achieve disease control. Secondary outcomes included other clinical responses. RESULTS: The number of days required to achieve disease control with treatment group was (7.60±3.00), which was shorter than in the control group (10.43±3.06) (p=0.008). The total amount of systemic corticosteroids was less and no serious infections were detected in the treatment group. LIMITATIONS: Single center, open-label study with short duration and small size. CONCLUSION: Our trial supports the potential of low-dose IL-2 therapy for patients with moderate to severe BP, which showed earlier treatment responses.

Validation of diagnostic criteria for atopic dermatitis and proposal of novel diagnostic criteria for adult and elderly Chinese populations: a multicentre, prospective, clinical setting-based study.

BACKGROUND: A previous validation study showed a very low sensitivity and higher specificity associated with Hanifin and Rajka criteria (H&R) and the UK Working Party criteria (UKWP) in diagnosing AD vs. the Chinese criteria of atopic dermatitis (AD) for children (CCAD). However, their diagnostic efficacy in adult and elderly Chinese populations remains unknown. OBJECTIVES: To validate the diagnostic efficacy of three sets of AD criteria in adult and elderly Chinese populations in a hospital setting. METHODS: A total of 1034 patients (aged 19-95 years) from five university hospital dermatological clinics were recruited. Medical history, dermatological examination, AD diagnosis and evaluation of AD severity were done by dermatologists. Each patient was investigated by two dermatologist panels, one to establish a clinical diagnosis, and the other to identify and record the major or minor signs of H&R criteria, UKWP criteria and CCAD. Taking clinical diagnosis as the reference, the diagnostic efficacy of three sets of diagnostic criteria was evaluated. The χ2 test or rank sum test were used for between-groups comparisons. RESULTS: CCAD had a higher sensitivity (84.0%), especially among mild and moderate cases of AD (72.7% and 90.3%, respectively), than the H&R (58.0%; P < 0.001) and UKWP criteria (56.0%; P < 0.001) in diagnosing AD. The specificity of CCAD (92.7%) was slightly lower than the H&R (97.3%; P < 0.001) or UKWP criteria (97.4%; P < 0.001). The CCAD had the highest Youden index (0.77), accuracy rate (0.90) and Kappa value (0.76) of the three sets of diagnostic criteria. CONCLUSIONS: Consistent with results in a population of Chinese children, although the H&R and UKWP criteria had a high specificity for diagnosing AD, their low sensitivity limited their use in adult and elderly Chinese patients. Based on the high sensitivity and favourable diagnostic efficacy, the CCAD is proposed for AD diagnosis in adult and elderly Chinese populations, especially for cases of mild and moderate AD.

Quality of Life Benefit and Clinical Predictors of Complete Skin Clearance in Psoriasis: A Multicenter, Prospective, Real-World Study.

BACKGROUND: Newer biologics, such as interleukin (IL)-17 inhibitors, make it possible to achieve complete skin clearance (CSC) in patients with moderate-to-severe psoriasis. However, the clinical meaningfulness and predictive factors of CSC in daily practice have not yet been fully investigated. OBJECTIVE: The study was conducted to, first, assess the impact of CSC on quality of life (QoL) improvements compared with treatment responses without clearance and, second, identify clinical parameters as predictors of CSC response in psoriasis patients treated with ixekizumab. METHODS: Patients attending 26 dermatology centers across China were recruited into this real-world setting between August 2020 and May 2022. Prospective cohort study in which response to ixekizumab was assessed using the Psoriasis Area and Severity Index (PASI) and Dermatology Quality of Life Index (DLQI). The absolute DLQI score and DLQI (0) response at week 12 were compared between groups achieving various levels of skin clearance. A stepwise logistic regression analysis was applied to identify which baseline clinical characteristics were predictive factors for CSC. RESULTS: After 12 weeks of treatment, 226 of 511 (44.2%) patients achieved CSC, defined as 100% improvement in PASI score (PASI-100). A significantly higher proportion of patients with CSC versus almost clear skin (PASI 90-99) achieved DLQI score of 0, corresponding to the experience of no impairment on QoL (54.4% vs. 37.7%, p = 0.001). Females patients were more likely than males to achieve CSC response (odds ratio [OR] = 1.83; 95% confidence interval [CI]: 1.24-2.70), while previous biologic treatment (OR = 0.43; 95% CI: 0.24-0.81) and joint affected (OR = 0.61; 95% CI: 0.42-0.89) were significantly associated with less CSC response. CONCLUSIONS: This study highlights the fact that clinical parameters are important in determining CSC response in psoriasis. In daily practice, achieving CSC represents a clinically meaningful treatment goal, especially from the patient perspective.

Thymic stromal lymphopoietin epigenetically upregulates Fc receptor γ subunit-related receptors on antigen-presenting cells and induces TH2/TH17 polarization through dectin-2.

BACKGROUND: Fc receptor γ subunit (FcRγ)-related receptors expressed on antigen-presenting cells (APCs) enhance allergen sensitization and allergic inflammation. DNA demethylation of the high-affinity IgE receptor γ subunit gene (FCER1G) leads to FcRγ and FcεRI overexpression on monocytes from patients with atopic dermatitis. OBJECTIVE: We investigated epigenetic mechanisms underlying FCER1G demethylation and upregulation of FcRγ-related receptors on APCs and the consequent effect on allergic responses. METHODS: Effects of thymic stromal lymphopoietin (TSLP) on expression of FcRγ and its related receptors and methylation or hydroxymethylation of FCER1G in human monocytes were assessed. Recruitment of ten-eleven translocation protein (TET) 2 to FCER1G by TSLP-activated phosphorylated signal transducer and activator of transcription 5 (pSTAT5) was evaluated. Effects of TSLP on expression of FcRγ-related receptors and costimulatory receptors on monocyte-derived dendritic cells (DCs) and the ability of DCs to take up ovalbumin were analyzed. TSLP-induced TH polarization and related cytokine production were also analyzed. RESULTS: pSTAT5 activation by TSLP resulted in TET2 recruitment to FCER1G, leading to FCER1G demethylation and subsequent upregulation of FcRγ-related receptors on monocytes. TSLP not only stimulated monocyte-derived DC maturation but also maintained their allergen uptake ability, likely through maintenance and upregulation of FcRγ-related receptors. Allergen sensitization and upregulation of TH2/TH17-related cytokines contributed to TSLP-DC-induced TH2/TH17 polarization. The latter was attenuated on neutralization with a dectin-2 antibody. CONCLUSIONS: TSLP mediated upregulation of FcRγ-related receptors on APCs through activation of pSTAT5, which recruited TET2 to induce FCER1G demethylation. TSLP-induced allergic TH2/TH17 polarization likely depends on dectin-2-mediated allergen sensitization and upregulation of TH2/TH17-related cytokines.

Epicutaneous sensitization with ovalbumin, staphylococcal enterotoxin B and vitamin D analogue induces atopic dermatitis in mice.

OBJECTIVE: To illuminate a method for establishment of a cost-efficient atopic dermatitis (AD) mouse model by topical application of ovalbumin (OVA), super-antigen staphylococcal enterotoxin B (SEB), and calcipotriene ointment (CO) on the back of BALB/c mice.
 Methods: Experimental mice were topically treated with OVA/SEB or OVA/SEB/CO every other day during 15 days of induction. Clinical alterations on the skin area were monitored every other day. Epidermal thickness were measured by reflectance confocal microscope (RCM) before harvest. Inflammatory cells in skin biopsies were marked by hematoxylin-eosin (HE) staining. Blood sample and skin biopsies were measured by ELISA and quantitative real-time PCR to detect the expression of IL-2, IL-4, IL-31, interferon (IFN)-γ, tumor necrosis factor (TNF)-α pruritus-associated nerve growth factor (NGF), and serum IgE.
 Results: Human AD-like cutaneous local inflammatory reaction was characterized by the accumulation of inflammatory cells, increased epidermal thickness and serum IgE levels as well as Th1 cell-associated cytokines (IFN-γ, TNF-α), Th2 cell-associated cytokines (IL-4, IL-31), and NGF in the OVA/SEB/CO group compared with that in the normal control group or the OVA/SEB group.
 Conclusion: OVA/SEB/CO can induce an AD-like mouse model with lower economic and time consumption.

Vitamin C inhibits NLRP3 inflammasome activation and delays the development of age-related hearing loss in male C57BL/6 mice.

The efficacy of vitamin C in age-related hearing loss, i.e., presbycusis, remains debatable. On a separate note, inflammation induced by the NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome is involved in the progression of presbycusis. In this study, we investigated the effect of vitamin C on male C57BL/6 mice's presbycusis and NLRP3 inflammasome. The results showed that vitamin C treatment improved hearing, reduced the production of inflammatory factors, inhibited NLRP3 inflammasome activation, and decreased cytosolic mitochondrial DNA (mtDNA) in the C57BL/6 mouse cochlea, inferior colliculus, and auditory cortex. According to this study, vitamin C protects auditory function in male C57BL/6 presbycusis mice through reducing mtDNA release, inhibiting the NLRP3 inflammasome activation in the auditory pathway. Our study provides a theoretical basis for applying vitamin C to treat presbycusis.

The Safety of Ixekizumab in Chinese Adults with Moderate-to-Severe Plaque Psoriasis: Analyses from a Prospective, Single-Arm, Multicenter, 12-Week Observational Study.

INTRODUCTION: Ixekizumab, a monoclonal antibody against interleukin-17A, is efficacious and well tolerated for the treatment of moderate-to-severe plaque psoriasis. However, there are limited data on the real-world safety of ixekizumab in Chinese patient populations. We performed an observational study of ixekizumab for the treatment of moderate-to-severe plaque psoriasis in routine clinical practice in China. Here we present a further safety analysis of this study. METHODS: In this prospective, observational, single-arm, multicenter, post-marketing safety study, adults (≥18 years) with moderate-to-severe plaque psoriasis receiving ixekizumab were enroled at dermatology departments in hospitals across China and prospectively followed for 12 weeks or until their last dose of ixekizumab. In this analysis, we evaluated adverse events (AEs) of special interest (AESIs) identified using MedDRA® search strategies. We also analyzed AEs and AESIs occurring in greater than ten patients in subgroups by age (< 65/≥ 65 years), sex, body weight (< 60/60 kg to < 80/≥ 80 kg), renal impairment, hepatic impairment, history of tuberculosis, history of HBV infection, recent or active infection, history of allergic reaction/hypersensitivity, and number (0-1/2-4/5-7) of ixekizumab 80 mg injections after baseline until day 105. RESULTS: This analysis included 663/666 patients enrolled in the primary study. At least one AESI was reported in 224 (33.8%) patients and considered related to ixekizumab in 181 (27.3%); the most common were injection site reactions (n = 131, 19.8%), infections (n = 80, 12.1%), and allergic reactions/hypersensitivity events (n = 59, 8.9%). The proportion of patients with ≥ 1 AE was higher for females versus males (99/186, 53.2% versus 184/477, 38.6%, p = 0.0006). The proportion of patients with ≥ 1 AE increased with the number of ixekizumab injections after baseline [61/188 (32.4%) for zero to one injection, 151/338 (44.7%) for two to four injections, and 61/106 (57.5%) for five to seven injections; p = 0.0001]. CONCLUSIONS: In this real-world study, ixekizumab was well tolerated in Chinese patients with moderate-to-severe plaque psoriasis, with no difference in safety across most patient subgroups.

Effectiveness of Ixekizumab in Chinese Patients with Moderate-Severe Plaque Psoriasis with Special Area Involvement: Subanalysis of a Prospective, Multicenter, Observational Real-World Study.

INTRODUCTION: Ixekizumab, a monoclonal antibody against interleukin-17A, demonstrated effectiveness in the treatment of psoriasis in a Chinese real-world study that was consistent with previous randomized controlled trials. Here, we report further analyses from this study to explore the effectiveness of ixekizumab for treating patients with psoriasis and the involvement of special body areas (scalp, nail, joint, palmoplantar, or genital areas). METHODS: A multicenter, prospective, observational, single-arm, post-marketing surveillance study was conducted in patients aged ≥ 18 years with moderate-to-severe plaque psoriasis and prescribed with ixekizumab in 26 Chinese hospitals. Psoriasis Area and Severity Index (PASI) and Dermatology Life Quality Index (DLQI) scores were compared between patients with versus without psoriasis in special body areas in the overall study population and across subgroups by body area. RESULTS: In total, 612 patients were included. At baseline, most patients (93.6%) had psoriasis involvement in at least one special body area. Overall, patients with psoriasis in special body areas reported a worse quality of life (QoL) than those without. Patients with versus without psoriasis in special body areas achieved a comparable mean reduction from baseline in PASI score (10.9 vs. 9.2 at week 2, and 16.9 vs. 14.7 at week 12, respectively) and DLQI score (6.0 vs. 4.4 at week 2, and 9.9 vs. 7.5 at week 12, respectively); a similar proportion of patients also achieved PASI 50 at week 2, and PASI 75 and PASI 90 at week 12, and a DLQI (0/1) at weeks 2 and 12. Several significantly different results were reported between subgroups, the majority of which favored patients with special body area involvement. CONCLUSION: Most patients had psoriasis involvement in a special body area which was associated with worse QoL. Ixekizumab is similarly effective in reducing disease severity and improving QoL in patients with plaque psoriasis across different special body areas.

IL-4-induced decrease in both the number and CTLA-4 expression of Treg impairs suppression of Th2 type inflammation in severe atopic dermatitis.

BACKGROUND: Treg plays a pivotal role in the suppression of Th2 cell and the maintenance of immune homeostasis. The precise molecular mechanism underlying the disruption of Treg suppression of Th2 cell and the promotion of Th2 type inflammation in allergic diseases remains elusive. OBJECTIVE: This study aims to investigate the molecular mechanism underlying quantitative and functional changes of Treg in AD. METHODS: The molecular mechanism was investigated using flow cytometry, mRNA sequencing, co-culture experiments, co-immunoprecipitation, chromatin immunoprecipitation, and bisulfite sequencing in vitro or in AD mice model and patients with AD. RESULTS: Increased proportion of Treg was detected in mild and moderate AD. Conversely, characteristic decrease in both the number and CTLA-4 expression of Treg was relevant to serum IL-4 level in severe AD patients, which was verified under a high concentration of IL-4 treatment in vitro. The underlying mechanism is that IL-4/pSTAT6 pathway recruits DNMT1 and HDAC2 to inhibit transcriptional regulation of Foxp3 and CTLA-4 loci. High level of IL-4 impaired the suppression of Treg against Th2 cell differentiation mediated by CTLA-4, and blockade of IL-4Rα signaling in Treg restored Treg number and suppression of Th2 cell in AD model mice and patients with AD. CONCLUSION: The number of Treg is relevant to stratification of severity and serum IL-4 level in patients with AD. Abnormal high level of IL-4 epigenetically triggers a decrease in both the number and CTLA-4 expression of Treg. The reduced expression of CTLA-4 on Treg induced by IL-4 impairs suppression of Th2 cell differentiation.

Dynamic pathological analysis reveals a protective role against skin fibrosis for TREM2-dependent macrophages.

Rationale: Systemic sclerosis (SSc) is a chronic and incurable autoimmune disease with high mortality rates, and skin fibrosis is one of distinguishing hallmarks in the pathogenesis. However, macrophage heterogeneity regulating skin fibrosis remain largely unknown. Methods: We established mouse disease model and performed single-cell RNA-sequencing (scRNA-seq) to resolve the dynamic and heterogenous characteristics of macrophages in skin fibrosis, and the role of TREM2-dependent macrophages in the pathological process was investigated using knockout mice and intraperitoneal transferring TREM2+ macrophages combining with functional assays. Results: We show that TREM2-expressing macrophages (TREM2+ MФs) accumulate in injured skin of mice treated by bleomycin (BLM) and human SSc, and their gene signatures and functional pathways are identified in the course of disease. Genetic ablation of Trem2 in mice globally accelerates and aggravates skin fibrosis, whereas transferring TREM2hi macrophages improves and alleviates skin fibrosis. Amazingly, we found that disease-associated TREM2+ MФs in skin fibrosis exhibit overlapping signatures with fetal skin counterparts in mice and human to maintain skin homeostasis, but each has merits in skin remodeling and development respectively. Conclusion: This study identifies that TREM2 acts as a functional molecule and a major signaling by which macrophage subpopulations play a protective role against fibrosis, and disease-associated TREM2+ MФs in skin fibrosis might undergo a fetal-like reprogramming similar to fetal skin counterparts.

Decreased microRNA-142-3p/5p expression causes CD4+ T cell activation and B cell hyperstimulation in systemic lupus erythematosus.

OBJECTIVE: To examine the role of microRNA-142-3p/5p (miR-142-3p/5p) in the development of autoimmunity in patients with systemic lupus erythematosus (SLE). METHODS: MicroRNA-142-3p/5p expression levels were determined by real-time quantitative polymerase chain reaction, and potential target genes were verified using luciferase reporter gene assays. The effects of miR-142-3p/5p on T cell function were assessed by transfection with miR-142-3p/5p inhibitors or mimics. Histone modifications and methylation levels within a putative regulatory region of the miR-142 locus were detected by chromatin immunoprecipitation assay and bisulfite sequencing, respectively. RESULTS: We confirmed that miR-142-3p and miR-142-5p were significantly down-regulated in SLE CD4+ T cells compared with healthy controls and observed that miR-142-3p/5p levels were inversely correlated with the putative SLE-related targets signaling lymphocytic activation molecule-associated protein (SAP), CD84, and interleukin-10 (IL-10). We demonstrated that miR-142-3p and miR-142-5p directly inhibit SAP, CD84, and IL-10 translation, and that reduced miR-142-3p/5p expression in CD4+ T cells can significantly increase protein levels of these target genes. Furthermore, inhibiting miR-142-3p/5p in healthy donor CD4+ T cells caused T cell overactivation and B cell hyperstimulation, whereas overexpression of miR-142-3p/5p in SLE CD4+ T cells had the opposite effect. We also observed that the decrease in miR-142 expression in SLE CD4+ T cells correlated with changes to histone modifications and DNA methylation levels upstream of the miR-142 precursor sequence. CONCLUSION: The results of this study indicate that reduced expression of miR-142-3p/5p in the CD4+ T cells of patients with SLE causes T cell activity and B cell hyperstimulation.

[Demethylation pattern of PD-1 gene in promoter region is associated with the PD-1 expression on peripheral blood mononuclear cells in chronic hepatitis B patients].

OBJECTIVE: To observe the expression variations and influencing factors of programmed death one (PD-1) and DNA demethylation of PD-1 promoter on peripheral blood mononuclear cells (PBMCs) in chronic hepatitis B (CHB) patients and further investigate the relationship between the demethylation pattern of PD-1 gene in promoter region and the PD-1 expression on PBMC in CHB patients. METHODS: A total of 162 subjects, including 144 CHB patients and 18 healthy blood donors, were enrolled. The expression of PD-1 on PBMCs was detected by flow cytometry. And the serum HBV markers, HBV DNA load and liver function were also measured. DNA of PBMCs was treated with sodium bisulfite; the PD-1 promoter fragments were amplified by polymerase chain reaction (PCR) and then transformed into Escherichia coli. Positive clones were selected for sequencing and the methylation status of fragments of PD-1 promoter was examined. RESULTS: With the PD-1 expression in normal controls (10.8% ± 4.4%) as a baseline level, the expression of PD-1 in CHB patients significantly increased. In CHB patients, the serum expression of PD-1 in PBMCs from patients with positive HBeAg (27.1% ± 18.4%) was much higher than that from those with negative HBeAg (19.6% ± 15.6%). And the expression level of PD-1 was not correlated with serum HBV DNA load and serum level of alanine aminotransferase. The results of bisulfite genomic sequencing showed that demethylation probability of some CG points in PD-1 promoter region (-601, -553, -538, -483, -463, -317 bp) were significantly correlated with PD-1 expression level (P < 0.05). CONCLUSION: The demethylation pattern of PD-1 gene in promoter region is associated with the PD-1 expression on PBMC in CHB patients.

[DNA methylation status of miR-126 and its host gene EGFL7 in CD4+ T cells from patients with systemic lupus erythematosus].

OBJECTIVE: To explore the mechanisms by which DNA methylation regulates miR-126 and its host gene EGFL7 in CD4+ T cells from patients with systemic lupus erythematosus (SLE). METHODS: We analyzed the expression and the DNA methylation status within promoter region of EGFL7 and miR-126 by real-time qPCR and bisulfite genomic sequencing analysis. RESULTS: miR-126 and EGFL7 mRNA expression was upregulated in CD4+ T cells from SLE compared with that from healthy controls (P<0.01). EGFL7 mRNA level was positively correlated with miR-126 expression in CD4+ T cells from SLE (r=0.538, P=0.015). The average methylation level of EGFL7 promoter in CD4+ T cells from SLE was lower than that from healthy controls (P<0.05). CONCLUSION: The upregulation of miR-126 and its host gene EGFL7 expression in CD4+ T cells from SLE is associated with the hypomethylation of the EGFL7 promoter.

[Construction of special reporter to detect DNA methylation regulatory activity in FCER1G gene promoter through patch-methylation].

OBJECTIVE: To construct a special luciferase reporter to detect DNA methylation regulatory activity in FCER1G gene promoter regulatory element. METHODS: We constructed special full and mock methylated FCER1G gene promoter regulatory luciferase reporters by patch-methylation, and detected DNA methylation regulatory activity by comparing the luciferase activity of full-methylated luciferase reporters with mock-methylated reporters. RESULTS: We successfully constructed the full and mock methylated FCER1G gene promoter regulatory luciferase reporters. The ratio of luciferase activity between the full methylated and the mock methylated was (0.36±0.07):1 (P<0.001). CONCLUSION: FCER1G promoter activity is methylation-sensitive and is regulated by DNA methylation.

Sodium thiosulfate inhibits epithelial-mesenchymal transition in melanoma via regulating the Wnt/ß-catenin signaling pathway.

BACKGROUND: Melanoma is the most common form of skin cancer. Given its high metastasis and high recurrence, its therapies are constantly updated. OBJECTIVE: The study aims to prove the efficacy of sodium thiosulfate (STS), an antidote to cyanide or nitroprusside poisoning, in melanoma treatment. METHODS: We tested the effect of STS by culturing melanoma cells (B16 and A375) in vitro and establishing melanoma mouse models in vivo. The proliferation and viability of melanoma cells were measured by the CCK-8 test, cell cycle assay, apoptosis analysis, wound healing assay, and transwell migration assay. The expression of apoptosis-related molecules, epithelial-mesenchymal transition (EMT)-associated molecules, and the Wnt/ß-catenin signaling pathway-related molecules were determined by Western blotting and immunofluorescence. RESULTS: The high metastasis of melanoma is considered to be linked to the EMT process. The scratch assay using B16 and A375 cells also showed that STS could inhibit the EMT process of melanoma. We demonstrated that STS inhibited the proliferation, viability, and EMT process of melanoma by releasing H2S. STS-mediated weakening of cell migration was related to the inhibition of the Wnt/ß-catenin signaling pathway. Mechanistically, we defined that STS inhibited the EMT process via the Wnt/ß-catenin signaling pathway. CONCLUSIONS: These results suggest that the negative effect of STS on melanoma development is mediated by the reduction of EMT via the regulation of the Wnt/ß-catenin signaling pathway, which provides a new clue to treating melanoma.

MicroRNA-126 regulates DNA methylation in CD4+ T cells and contributes to systemic lupus erythematosus by targeting DNA methyltransferase 1.

OBJECTIVE: To identify microRNA genes with abnormal expression in the CD4+ T cells of patients with systemic lupus erythematosus (SLE) and to determine the role of microRNA-126 (miR-126) in the etiology of SLE. METHODS: MicroRNA expression patterns in CD4+ T cells from patients with SLE and healthy control subjects were analyzed by microRNA microarray and stem loop quantitative polymerase chain reaction (qPCR). Luciferase reporter gene assays were performed to identify miR-126 targets. Dnmt1, CD11a, and CD70 messenger RNA and protein levels were determined by real-time qPCR, Western blotting, and flow cytometry. CD11a, CD70, and EGFL7 promoter methylation levels were detected by bisulfite sequencing. IgG levels in T cell-B cell cocultures were determined by enzyme-linked immunosorbent assay. RESULTS: The expression of 11 microRNA was significantly increased or decreased in CD4+ T cells from patients with SLE relative to that in CD4+ T cells from control subjects. Among these, miR-126 was up-regulated, and its degree of overexpression was inversely correlated with Dnmt1 protein levels. We demonstrated that miR-126 directly inhibits Dnmt1 translation via interaction with its 3'-untranslated region, and that overexpression of miR-126 in CD4+ T cells can significantly reduce Dnmt1 protein levels. The overexpression of miR-126 in CD4+ T cells from healthy donors caused the demethylation and up-regulation of genes encoding CD11a and CD70, thereby causing T cell and B cell hyperactivity. The inhibition of miR-126 in CD4+ T cells from patients with SLE had the opposite effects. Expression of the miR-126 host gene EGFL7 was also up-regulated in CD4+ T cells from patients with SLE, possibly in a hypomethylation-dependent manner. CONCLUSION: Our data suggest that miR-126 regulates DNA methylation in CD4+ T cells and contributes to T cell autoreactivity in SLE by directly targeting Dnmt1.