JAK2-STAT3 Blockade by AG490 Suppresses Autoimmune Arthritis in Mice via Reciprocal Regulation of Regulatory T Cells and Th17 Cells

Abstract

IL-6–mediated STAT3 signaling is essential for Th17 differentiation and plays a central role in the pathogenesis of rheumatoid arthritis. To investigate the molecular mechanism underlying the antirheumatic effects and T cell regulatory effects of STAT3 inhibition, we studied the effects of the JAK 2 inhibitor AG490 on Th17 cell/regulatory T cell (Treg) balance and osteoclastogenesis. AG490 was administered to mice with collagen-induced arthritis (CIA) via i.p. injection, and its in vivo effects were determined. Differential expression of proinflammatory cytokines, including IL-17A, IL-1β, and IL-6, was analyzed by immunohistochemistry. Levels of phosphorylated STAT3 and STAT5 and differentiation of Th17 cells and Tregs after AG490 treatment in our CIA model were analyzed by immunostaining. In vitro development of Th17 cells and Tregs was analyzed by flow cytometry and real-time PCR. AG490 ameliorated the arthritic phenotype in CIA and increased the proportion of Foxp3+ Tregs. In contrast, the proportion of IL-17A–producing T cells and levels of inflammatory markers were reduced in AG490-treated mice. Numbers of p-STAT3+ CD4+ T cells and p-STAT5+ CD4+ T cells were reduced and elevated, respectively, after treatment with AG490. Furthermore, AG490 markedly increased the expression of molecules associated with Treg development (ICOS, programmed cell death protein 1, ICAM-1, and CD103). The development and function of osteoclasts were suppressed by AG490 treatment. Our results suggest that AG490, specifically regulating the JAK2/STAT3 pathway, may be a promising treatment for rheumatoid arthritis.

Novel synthetic (E)-2-methoxy-4-(3-(4-methoxyphenyl) prop-1-en-1-yl) phenol inhibits arthritis by targeting signal transducer and activator of transcription 3

“…Small molecules targeting STAT3 have been demonstrated as potential pharmaceutical drugs for chronic joint inflammation and RA9101112. Previously, a DNA-binding site in the STAT3 core fragment was identified as a critical position for regulating STAT3 activity by small molecules2728.…”

“…For example, tofacitinib (an oral Janus kinase 3 [JAK3] tyrosine kinase inhibitor, Pfizer Inc.), which inhibits STAT3 phosphorylation, was approved by the US Food and Drug Administration (FDA) for the treatment of patients with RA who are unresponsive to disease-modifying antirheumatic drug (DMARD) therapy10. Further, recent studies showed that the non-peptide small molecules, STA-21 (STAT3 inhibitor) and AG490 (JAK2-STAT3 pathway inhibitor) improve the treatment efficacy considerably in active RA1112. Therefore, pharmaceutical approaches and advancements in STAT3-targeted small molecules have emerged as promising pharmacological therapies for RA.…”

Sinomenine induces the generation of intestinal Treg cells and attenuates arthritis via activation of aryl hydrocarbon receptor

“…For the analysis of cell apoptosis, cells were stained with Annexin V and 7-AAD, and loaded on the flow cytometer. 12 Flow cytometric analysis was performed in a FACSCalibur instrument and analyzed with FlowJo software.…”

The role of the JAK-STAT pathway in neural stem cells, neural progenitor cells and reactive astrocytes after spinal cord injury

“…The study by Yamauchi et al (104) revealed that pretreatment with the JAK2 inhibitor, AG-490 (108) reduced the functional recovery of hindlimbs after SCI, which indicated that activation of the JAK-STAT pathway induced by IL-6 in neurons may contribute to neuroprotection after SCI. As an effective trophic factor and pro-inflammatory factor, the LIF concentration increased within 24 h following SCI, indicating its vital role in regulating inflammatory reactions and preservation of oligodendrocyte following SCI (80,109). Although NGF and CNTF have diverse effects on the CNS, including differentiation and proliferation, they are able to enhance the survival of oligodendrocyte progenitors in CNS (110-117).…”