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 5

CTRP4 negatively regulates IL-6–induced STAT3 activation through the IL-6/IL-6R axis.

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CTRP4 negatively regulates IL-6–induced STAT3 activation through the IL-...
(A) Jurkat cells transduced with lentivirus encoding pmCherry-CTRP4 and EGFP–IL-6R were observed using laser confocal microscopy. Higher magnification images of boxed areas of lower power images are provided. Original magnification, ×80; ×100. (B) Coimmunoprecipitation of membrane protein from Jurkat cell lysates by anti–IL-6R antibody and anti-CTRP4 antibody. (C) Cell membrane extracts from differentiated Th17 cells were coimmunoprecipitated by anti–IL-6R and then immunoblotted with anti-CTRP4 antibody (D) HEK293T were transfected with plasmid encoding Myc-tagged CTRP4 and Flag-tagged IL-6R truncated forms, followed by immunoblotting with indicated antibodies. (E) Equivalent quantities of Jurkat cell extract were incubated with serial dilutions of 125I-CTRP4 to calculate saturation curves. (F) Competitive binding assays were performed by addition of unlabeled rhCTRP4 to disturb the interaction between125I-CTRP4 and IL-6R. (G) HEK293T cells were transfected with plasmid encoding EGFP–IL-6R and pmCherry–IL-6 with or without rhCTRP4 to detect IL-6 binding to IL-6R. Original magnification, ×100. (H) rhCTRP4 or BSA was incubated with solid-phase 200 ng/mL IL-6R to detect the interaction between CTRP4 and IL-6R by ELISA. (I) Competitive blockade assays were performed adding 200 ng/mL IL-6 to compete with CTRP4 for binding to IL-6. (J) Jurkat cells transduced with retrovirus encoding Flag-tagged IL-6 or Flag-tagged IL-6 plus Myc-tagged CTRP4 were coimmunoprecipitated with anti-Flag antibody. (K) Serum levels of CTRP4 and IL-6 were determined by ELISA before model induction or at the peak of EAE. (L) Differentiation of CD4+ cells transfected with siRNA-nucleolin into Th17 cells was assessed in the presence or absence of rhCTRP4. (H–L) Data are represented as mean ± SEM obtained from independent experiments with similar results. The samples derived from the same experiment and gels/blots were processed in parallel. Statistical significance was determined using 2-tailed, unpaired Student’s t test or 1-way ANOVA with Tukey’s post test. ***P < 0.001.