Rheumatoid arthritis synovial fluid induces JAK-dependent intracellular activation of human sensory neurons
Yuening Li, Elizabeth H. Gray, Rosie Ross, Irene Zebochin, Amy Lock, Laura Fedele, Louisa Janice Kamajaya, Rebecca J. Marrow, Sarah Ryan, Pascal Röderer, Oliver Brüstle, Susan John, Franziska Denk, Leonie S. Taams
Yuening Li, Elizabeth H. Gray, Rosie Ross, Irene Zebochin, Amy Lock, Laura Fedele, Louisa Janice Kamajaya, Rebecca J. Marrow, Sarah Ryan, Pascal Röderer, Oliver Brüstle, Susan John, Franziska Denk, Leonie S. Taams
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Research Article Immunology Inflammation Neuroscience

Rheumatoid arthritis synovial fluid induces JAK-dependent intracellular activation of human sensory neurons

Abstract

JAK inhibitors (JAKi) are widely used antiinflammatory drugs. Recent data suggest that JAKi have superior effects on pain reduction in rheumatoid arthritis (RA). However, the underlying mechanisms for this observation are not fully understood. We investigated whether JAKi can act directly on human sensory neurons. We analyzed RNA-seq datasets of sensory neurons and found that they expressed JAK1 and STAT3. Addition of cell-free RA synovial fluid to human induced pluripotent stem cell–derived (iPSC-derived) sensory neurons led to phosphorylation of STAT3 (pSTAT3), which was completely blocked by the JAKi tofacitinib. Compared with paired serum, RA synovial fluid was enriched for the STAT3 signalling cytokines IL-6, IL-11, LIF, IFN-α, and IFN-β, with their requisite receptors present in peripheral nerves postmortem. Accordingly, these recombinant cytokines induced pSTAT3 in iPSC-derived sensory neurons. Furthermore, IL-6 + sIL-6R and LIF upregulated expression of pain-relevant genes with STAT3-binding sites, an effect that was blocked by tofacitinib. LIF also induced neuronal sensitization, highlighting this molecule as a putative pain mediator. Finally, over time, tofacitinib reduced the firing rate of sensory neurons stimulated with RA synovial fluid. Together, these data indicate that JAKi can act directly on human sensory neurons, providing a potential mechanistic explanation for their suggested superior analgesic properties.

Authors

Yuening Li, Elizabeth H. Gray, Rosie Ross, Irene Zebochin, Amy Lock, Laura Fedele, Louisa Janice Kamajaya, Rebecca J. Marrow, Sarah Ryan, Pascal Röderer, Oliver Brüstle, Susan John, Franziska Denk, Leonie S. Taams

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Figure 6

IL-6 + sIL-6R and LIF increase the expression of pain-relevant genes with pSTAT3 binding sites, which is reversed by JAKi.

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IL-6 + sIL-6R and LIF increase the expression of pain-relevant genes wit...
(A) ChIP sequencing dataset (23) showing pSTAT3 binding sites in Socs3, Atf3, Bdnf, and Csf1 in mouse DRG neurons. (B) IPSC-derived sensory neurons were treated without or with 100 ng/mL IL-6 + sIL-6R for 24 hours, followed by qPCR analysis. Boxplots showing gene expression of the indicated genes. Data derived from n = 9 culture wells using three independent differentiations (designated by the prefix “T”) from two iPSC lines (day 67–76). (C) IPSC-derived sensory neurons were treated without or with IL-6 + sIL-6R or LIF (all at 100 ng/mL) for 24 hours in the absence or presence of tofacitinib (2 μM), followed by qPCR analysis. Boxplots showing expression of the indicated genes. Data are derived from n = 6 neuronal wells derived from two independent iPSC lines (day 57–61). Statistical significance was determined by 1-tailed nonparametric t tests to compare between with or without IL-6 + sIL-6R (B) or with or without tofacitinib in the presence of IL-6 + sIL-6R or LIF (C). Neurons aged day 57–76 were used. P < 0.013 was deemed significant after Bonferroni correction and marked by an asterisk.