Role of ITK signaling in acute kidney injury in mice: Amelioration of acute kidney injury associated clinical parameters and attenuation of inflammatory transcription factor signaling in CD4+ T cells by ITK inhibition

Abstract Background Acute kidney injury (AKI), with a high morbidity and mortality, is recognized as a risk factor for chronic kidney disease (CKD). AKI-CKD transition has been regarded as one of the most pressing unmet needs in renal diseases. Recently, studies have showed that salt inducible kinase 1 (SIK1) plays a role in epithelial-mesenchymal transition (EMT) and inflammation, which are the hallmarks of AKI-CKD transition. However, whether SIK1 is involved in AKI-CKD transition and by what mechanism it regulates AKI-CKD transition remains unknown. Methods We firstly detected the expression of SIK1 in kidney tissues of AKI patients and AKI mice by immunohistochemistry staining, and then we established Aristolochic acid (AA)-induced AKI-CKD transition model in C57BL/6 mice and HK2 cells. Subsequently, we performed immunohistochemistry staining, ELISA, real-time PCR, Western blot, immunofluorescence staining and Transwell assay to explore the role and underlying mechanism of SIK1 on AKI-CKD transition. Results The expression of SIK1 was down-regulated in AKI patients, AKI mice, AA-induced AKI-CKD transition mice, and HK2 cells. Functional analysis revealed that overexpression of SIK1 alleviated AA-induced AKI-CKD transition and HK2 cells injury in vivo and in vitro. Mechanistically, we demonstrated that SIK1 mediated AA-induced AKI-CKD transition by regulating WNT/β-catenin signaling, the canonical pathway involved in EMT, inflammation and renal fibrosis. In addition, we discovered that inhibition of WNT/β-catenin pathway and its downstream transcription factor Twist1 ameliorated HK2 cells injury, delaying the progression of AKI-CKD transition. Conclusions Our study demonstrated, for the first time, a protective role of SIK1 in AKI-CKD transition by regulating WNT/β-catenin signaling pathway and its downstream transcription factor Twist1, which will provide novel insights into the prevention and treatment AKI-CKD transition in the future.

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Regulation of Autoreactive CD4 T Cells by FoxO1 Signaling in CNS Autoimmunity

10.21203/rs.3.rs-322045/v1 ◽

2021 ◽

Author(s):

Emma E. Kraus ◽

Laura Kakuk-Atkins ◽

Marissa F. Farinas ◽

Mathew Jeffers ◽

Amy E. Lovett-Racke ◽

...

Keyword(s):

T Cells ◽

Transcription Factor ◽

Cd4 T Cells ◽

Th17 Cells ◽

Foxp3 Expression ◽

Treg Cells ◽

Th1 Cells ◽

T Effector Cells ◽

Cns Autoimmunity

Abstract BackgroundMyelin-specific CD4 T effector cells (Teffs), Th1 and Th17 cells, are encephalitogenic in experimental autoimmune encephalomyelitis (EAE), a well-defined murine model of multiple sclerosis (MS) and implicated in MS pathogenesis. Forkhead box O 1 (FoxO1) is a conserved effector molecule in PI3K/Akt signaling and critical in the differentiation of CD4 T cells into T helper subsets. However, it is still unclear whether FoxO1 may be a target for redirecting CD4 T cell differentiation and benefit CNS autoimmunity. MethodsUsing a selective FoxO1 inhibitor AS1842856, we determined the effects of FoxO1 inhibition in regulating myelin-specific Th1 and Th17 cells, and the transcriptional balance of T-bet and Foxp3 in myelin-specific CD4 T cells from EAE mice. The effects of AS1842856 in regulating the encephalitogenicity of myelin-specific T cells and the expansion of human Th1 cells from MS patients were also characterized. Furthermore, we characterized the potential role of FoxO1 in mediating PD-1 signaling in CD4 T cells, critical for regulating Teff and Treg cells. ResultsInhibition of FoxO1 suppressed the differentiation and expansion of Th1 cells. Moreover, the transdifferentiation of Th17 cells into encephalitogenic Th1-like cells was suppressed by FoxO1 inhibition upon reactivation of myelin-specific CD4 T cells from mice with EAE. When FoxO1 was inhibited in myelin-specific CD4 T cells, the transcriptional balance skewed from the Th1 transcription factor T-bet toward the Treg transcription factor Foxp3. Myelin-specific CD4 T cells treated with the FoxO1 inhibitor were less encephalitogenic in adoptive transfer EAE studies compared to control-treated cells. Inhibition of FoxO1 in T cells from MS patients significantly suppressed the expansion of Th1 cells. Furthermore, the immune checkpoint programmed cell death protein-1 (PD-1)-induced Foxp3 expression in CD4 T cells was impaired by FoxO1 inhibition, consistent with a bias toward Treg induction. ConclusionsThese data illustrate an important role of FoxO1 signaling in CNS autoimmunity via regulating autoreactive Teff and Treg balance.

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