Background. Interferon-inducible 44 like (IFI44L) is a newly discovered interferon-induced gene and has been reported to overexpress in systemic lupus erythematosus (SLE). However, little is known about the mechanism and function of IFI44L overexpression in SLE. In this study, we aimed to investigate the epigenetic mechanism of IFI44L overexpression in SLE monocyte and its potential functions contributing to the pathogenesis of SLE. Methods. We collected peripheral blood from 20 SLE patients and 20 healthy controls. Expression of IFI44L in monocytes and effects of different signal transducers and activators of transcription (STAT) pathway inhibitors on IFI44L expression were detected. Recruitment of ten-eleven translocation protein (TET) by STAT and methylation of IFI44L promoter were evaluated. Effects of IFI44L overexpression on the expression of surface markers on monocyte-derived dendritic cells (Mo-DCs) were analyzed. T cell differentiation mediated by Mo-DCs and related cytokines production were also analyzed. Results. Expression level of IFI44L was significantly increased in SLE monocyte. IFI44L expression was decreased most significantly in STAT3 inhibitor compared with other inhibitors. STAT3 regulated IFI44L expression and interacted with TET2 which induced DNA demethylation of IFI44L promoter. Overexpression of IFI44L in monocyte enhanced the maturation and functions of Mo-DC by upregulating costimulatory receptors and inducing Th1/Th17-related cytokines when cocultured with nave CD4⁺ T cells. Conclusion. TET2 recruited by STAT3 induces DNA demethylation of IFI44L promoter which promotes IFI44L overexpression in monocyte contributing to the pathogenesis of SLE by enhancing the maturation and functions of Mo-DC. IFI44L is expected to become a new target for treatment of SLE.

Purpose: Amyopathic dermatomyositis (ADM) is a rare, idiopathic, connective tissue disease and melanoma differentiation-associated protein 5 (MDA5) antibody-positive ADM is more treatment-resistant, especially in patients with interstitial lung disease (ILD). The purpose of this article is to report a case of anti-MDA5-positive ADM successfully treated with JAK inhibitor Upadacitinib. Materials and methods: A 35-year-old Chinese woman presented with recurrent itchy erythema on her face and scalp for 4 years. Upon examination, there were heliotrope erythema and eyelid edema, reddish rash on neck and scalp. Biopsy of the lesions was consistent with DM and a line blot assay confirmed the presence of anti-MDA5 antibodies. This patient was treated with oral Upadacitinib at a dosage of 30 mg daily. Results: After 6 weeks of treatment, she achieved complete clinical remission with no reported side effects or instances of relapse. The antibody titer of anti-MDA5 was also decreased. Conclusions: Upadacitinib may be a potential drug candidate in patients with treatment-resistant ADM, especially in cases with refractory cutaneous conditions.

T follicular helper (Tfh) cells are overactivated in systemic lupus erythematosus (SLE) patients and contribute to excessive immunity. Hematopoietic progenitor kinase 1 (HPK1), as an inhibitor of T cells, is underexpressed in SLE Tfh cells and consequently induces autoimmunity. However, the reason for downregulation of HPK1 in SLE Tfh cells remains elusive. By combining chromatin immunoprecipitation with quantitative polymerase chain reaction assays, it was found that histone H3 lysine 27 trimethylation (H3K27me3) at the HPK1 promoter in SLE Tfh cells elevated greatly. We also confirmed jumonji domain-containing 3 (JMJD3) binding at the HPK1 promoter in SLE Tfh cells reduced profoundly. Knocking down JMJD3 in normal Tfh cells with siRNA alleviated enrichments of JMJD3, H3K4me3, and mixed-lineage leukemia (MLL) 1 at the HPK1 promoter and increased H3K27me3 number in the region. HPK1 expression was lowered, while Tfh cell proliferation activity, IL-21 and IFNγ secretions in the supernatants of Tfh cells, and IgG1 and IgG3 concentrations in the supernatants of Tfh-B cell cocultures all upregulated markedly. In contrast, elevating JMJD3 amount in SLE Tfh cells by JMJD3-overexpressed plasmid showed opposite effects. The abundances of H3K4me3 and MLL1 at the HPK1 promoter in SLE Tfh cells were greatly attenuated. Our results suggest that deficient JMJD3 binding at the promoter dampens HPK1 expression in SLE Tfh cells, thus making Tfh cells overactive, and ultimately results in onset of SLE.

Systemic lupus erythematosus (SLE) is a common autoimmune disease with high incidence in females. The pathogenesis of SLE is complex, and healing SLE has become a serious challenge for clinical treatment. Aberrant expression of miR-301a-3p involves the progressions of multiple diseases, and some studies have indicated that increased miR-301a-3p could induce the inflammatory injury of some organs. However, the role and molecular mechanism of miR-301a-3p in SLE remain unclear. In this study, the miR-301a-3p levels in peripheral blood mononuclear cells (PBMCs) of the patients with SLE and health subjects were measured with qRT-PCR. The ELISA assay was used to investigate the effect of miR-301a-3p on the levels of inflammatory factors in PBMCs, and flow cytometry assays were used to observe the effect of miR-301a-3p on the levels of CD4+ T cells and Th17 cells in PBMCs. Moreover, TargetScan, dual-luciferase reporter assay, and western blot were used to reveal the downstream targets and regulation mechanism of miR-301a-3p in SLE. The results showed that miR-301a-3p was significantly upregulated in PBMCs of the SLE patients, and increased miR-301a-3p could boost the expression of IL-6, IL-17, and INF-γ in PBMCs and promote the differentiation of Th17 cells. It was found that PELI1 was a target of miR-301a-3p, and PELI1 upregulation could effectively reverse the effect of miR-301a-3p on PBMCs. Besides, this study also found that miR-301a-3p could promote the expression of IRAK1 to involve the progression of SLE via targeting PELI1. In conclusion, this study suggests that increased miR-301a-3p serves as a pathogenic factor in SLE to promote IRAK1-mediated differentiation of Th17cells via targeting PELI1.