P176 TYK2 inhibition attenuates the stimulation of sensory neurons with hyper-IL-6

Abstract

Abstract Background Abdominal pain and diarrhoea are a cause of significant morbidity for people with colitis. Recent single cell RNA sequencing of sensory neurons innervating the gut highlights a likely role for sensory nerves in the pathophysiology of these symptoms based on the marked expression of cytokine receptors from the IL-6 receptor family in gut projecting sensory neurons. In keeping with the reported downstream signalling pathway for these receptors marked co-expression of TYK2 transcripts were also found along with IL-6 signal transducer (GP130) in colonic nociceptors characterised by expression of the capsaicin receptor TRPV1. These observations suggest that TYK2 inhibitors may ameliorate symptoms of pain and diarrhoea in people with colitis by preventing neurogenically mediated gut contractility and nociceptor activation. Methods TYK2 mediated sensory neuron activation: changes in the intracellular [Ca2+]i within thoracolumbar (T12-L5 spinal segments) dorsal root ganglia sensory neurons were examined in cells cultured overnight and loaded with Fluo-4-AM (30min) prior to imaging. Responses were measured to the hyper-IL-6 fusion protein of the soluble IL-6 receptor and IL-6, which transactivates the GP130 receptor subunit to mimic IL-6 family receptor signalling following pre-treatment with vehicle, the TYK2 inhibitor Deucravacitinib (100nM) or the pan-JAK inhibitor Pyridone-6 (2 μM). Afterwards cells were exposed to capsaicin (1 µM) followed by 50 mM KCl, to confirm the presence of nociceptors and neurons respectively by positive response. All experiments were performed using tissue from male C57/B6 mice euthanised by rising concentration of CO2followed by exsanguination in accordance with Schedule 1 of the UK Animals Scientific Procedures act (1986). Results Application of hyper-IL-6 produced a robust increase in [Ca2+]i levels in DRG sensory neurons which was significantly attenuated by pre-treatment with the TYK2 specific inhibitor Deucravacitinib (p<0.01) or the pan JAK inhibitor Pyridone-6 (p = <0.05). Conclusion Findings demonstrate that inhibition of TYK2 inhibitor prevents sensory neuron activation in response to IL-6 trans-signalling. This data suggests that TYK2 inhibitors may have utility for the treatment of abdominal pain in people with colitis.