Interleukin-17A (IL-17A)-producing helper T (Th17) cells are a subset of CD4 + T cells that play important pathological roles in autoimmune diseases. Although the intrinsic pathways of Th17 cell differentiation have been well described, how instructive signals derived from the innate immune system trigger the Th17 response and inflammation remains poorly understood. Here, we report that mice deficient in REGγ, a proteasome activator belonging to the 11S family, exhibit significantly deteriorated autoimmune neuroinflammation in an experimental autoimmune encephalomyelitis (EAE) model with augmented Th17 cell polarization in vivo. The results of the adoptive transfer of CD4 + T cells or dendritic cells (DCs) suggest that this phenotype is driven by DCs rather than T cells. Furthermore, REGγ deficiency promotes the expression of integrin αvβ8 on DCs, which activates the maturation of TGF-β1 to enhance Th17 cell development. Mechanistically, this process is mediated by the REGγ-proteasome-dependent degradation of IRF8, a transcription factor for αvβ8. Collectively, our findings delineate a previously unknown mechanism by which REGγ-mediated protein degradation in DCs controls the differentiation of Th17 cells and the onset of an experimental autoimmune disease.

Granular parakeratosis is an uncommon acquired keratinization disorder that occurs in the armpit, groin, and other parts of the body. It may be related to stimulation by detergents and antiperspirants. This article reports a case of granular parakeratosis in the groin. The patient was a young man with no predisposing factors. The clinical manifestations included symmetrical bilateral inguinal erythema, dryness, and a small amount of bran-like desquamation. After histopathological examination, the final diagnosis was granular parakeratosis, which was cured by topical application of glucocorticoid cream and silicone oil cream. Granular parakeratosis is a rare skin disease of unknown etiology. Clinicians need to pay attention to this disease and differentiate it from various diseases to avoid misdiagnosis.

Objective To investigate the expression level of TRAF3IP2 in psoriasis lesion, and to explore the functional roles of TRAF3IP2 on proliferation, apoptosis, cytokine expression and secretion of both keratinocytes and vascular endothelial cells in vitro . Methods The expression of TRAF3IP2 in skin samples of patients with psoriasis was analyzed by immunohistochemistry and qRT-PCR. To identify the effect of TRAF3IP2 knockdown on HaCaT and HUVEC cells, a plasmid vector expressing siRNA targeting TRAF3IP2 mRNA was designed and transfected into cells with Lipofectamine 2000. The levels of cytokines were identified using the ELISA Kits and qRT-PCR. Furthermore, cell proliferation, cell cycle and apoptosis were examined by using MTT, PI and Annexin V-FITC/7AAD assays, respectively. Furthermore, the expression of apoptosis-related proteins (Cleaved-Caspase 3, Caspase 3 and Bax) were detected by western blotting. Results TRAF3IP2 was significantly upregulated in psoriasis lesion. TRAF3IP2 knockdown reduced the expression of vascular endothelial growth factor A (VEGFA) and the release of IL-6, and IL-8, but had no effect on IL-23 in both HaCaT and HUVEC cells. In addition, knockdown of TRAF3IP2 significantly inhibited cell proliferation through blocking the cell cycle in the G2/M phase. Moreover, knockdown of TRAF3IP2 increased the expression of Caspase 3, Cleaved-Caspase 3 and Bax, which was supported by the increased apoptosis of both HaCaT and HUVEC cells. Conclusion Taken together, these results indicated that TRAF3IP2 might play a contributive role in the pathogenesis of psoriasis and may serve as a new target for the treatment of psoriasis. VEGF related pathways may be involved in the mechanism beneath.

The present study aimed to investigate the effects of interleukin-17 (IL-17) on the function of keratinocytes and to further investigate its associated mechanism. Human immortalized epidermal cells (HaCaT) were divided into sham control group (Sham), TRAF3 interacting protein 2 (TRAF3IP2)-knockdown with lentivirus group (si-TRAF3IP2), sham control+IL-17 group (Sham+IL-17) and TRAF3IP2-knockdown with lentivirus+IL-17 group (si-TRAF3IP2+IL-17). MTT and flow cytometry assays demonstrated that IL-17 promoted proliferation and inhibited apoptosis of HaCaT cells, while this effect was reversed following knockdown of TRAF3IP2 with lentiviral vectors. In addition, a marked increase in the levels of IL-6, IL-8, IL-23, TNF-α and VEGF was observed in the Sham+IL-17 group compared with that noted in the Sham group (P<0.05). Furthermore, reverse transcription-quantitative polymerase chain reaction and western blotting indicated that the mRNA and protein expression levels of caspase-3 in the si-TRAF3IP2+IL-17 group were significantly increased compared with those of the Sham+IL-17 group (P<0.05). Taken together, the results indicated that IL-17 promoted proliferation and inflammation and inhibited apoptosis of HaCaT cells by interacting with the TRAF3IP2 adaptor protein, while knockdown of the expression of TRAF3IP2 reduced the effects of IL-17 in HaCaT cells.