CTRP4/interleukin-6 receptor signaling ameliorates autoimmune encephalomyelitis by suppressing Th17 cell differentiation
Lulu Cao, … , Xiaoxin Zhu, Lu Wang
Lulu Cao, … , Xiaoxin Zhu, Lu Wang
Published November 28, 2023
Citation Information: J Clin Invest. 2024;134(4):e168384. https://doi.org/10.1172/JCI168384.
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Research Article Autoimmunity

CTRP4/interleukin-6 receptor signaling ameliorates autoimmune encephalomyelitis by suppressing Th17 cell differentiation

Abstract

C1q/TNF-related protein 4 (CTRP4) is generally thought to be released extracellularly and plays a critical role in energy metabolism and protecting against sepsis. However, its physiological functions in autoimmune diseases have not been thoroughly explored. In this study, we demonstrate that Th17 cell–associated experimental autoimmune encephalomyelitis was greatly exacerbated in Ctrp4–/– mice compared with WT mice due to increased Th17 cell infiltration. The absence of Ctrp4 promoted the differentiation of naive CD4+ T cells into Th17 cells in vitro. Mechanistically, CTRP4 interfered with the interaction between IL-6 and the IL-6 receptor (IL-6R) by directly competing to bind with IL-6R, leading to suppression of IL-6–induced activation of the STAT3 pathway. Furthermore, the administration of recombinant CTRP4 protein ameliorated disease symptoms. In conclusion, our results indicate that CTRP4, as an endogenous regulator of the IL-6 receptor–signaling pathway, may be a potential therapeutic intervention for Th17-driven autoimmune diseases.

Authors

Lulu Cao, Jinhai Deng, Wei Chen, Minwei He, Ning Zhao, He Huang, Lu Ling, Qi Li, Xiaoxin Zhu, Lu Wang

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Figure 6

Reconstitution of CTRP4 inhibits IL-6–mediated STAT3 activation.

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Reconstitution of CTRP4 inhibits IL-6–mediated STAT3 activation. (A) Pur...
(A) Purified CD4+ T cells from Ctrp4–/– and WT mice were stimulated with IL-6 (100 ng/mL) for indicated times. Lysates were subjected to Western blot analysis for indicated antibodies. (B) Freshly isolated WT and Ctrp4–/– CD4+ T cells were treated with IL-6 (100 ng/mL) for 30 minutes. Levels of p-STAT3 were determined by flow cytometry. (C) Representative flow cytometry analysis of p-STAT3 and p-STAT1 of CD4+ T cells from Ctrp4–/– and WT EAE-induced mice at the peak of disease. (D–F) WT CD4+ T cells were polarized to Th17. The intracellular IL-17A was analyzed by flow cytometry (D), and gene expression levels of Rorc mRNA were analyzed by quantitative real-time PCR (E). Supernatants were collected to determine levels of IL-17A by ELISA (F). (G) Purified WT naive CD4+ T cells were polarized under Th17 conditions with indicated doses of rhCTRP4. Quantification of the percentages of CD4+IL17A+ cells was analyzed by flow cytometry. (H) Purified WT CD4+ cells were activated with IL-6 (10 ng/mL) or rhCTRP4 (100 ng/mL) alone or treated with IL-6 prior to treatment with rhCTRP4 for 1 hour or without treatment as control. Western blot was performed to analyze the activation of STAT3. (I) Purified WT CD4+ cells were activated with IL-6 or with IL-6 pretreated with various concentrations of rhCTRP4 (100 ng/mL, 500ng/mL, and 1,000 ng/mL) followed by Western blot to analyze the activation of STAT3 and JAK2. The samples derived from the same experiment, and gels/blots were processed in parallel. Representative of 3 independent experiments with 5 mice per experiment. (J) Purified WT CD4+ cells were activated with IL-6 (10 ng/mL) prior to treatment with rhCTRP4 (100 ng/mL) for the indicated times. Time-dependent changes in the levels of p-STAT3 were evaluated by Western blot. Data are represented as mean ± SEM and are from 1 of 3 independent experiments with similar results. (D–F) Statistical significance was determined using paired Student’s t test; (G) statistical significance was determined using 1-way ANOVA with Tukey’s post test. *P < 0.05; **P < 0.01.