#4372 TYK2-INDUCED STAT ACTIVATION IS ESSENTIAL FOR VASCULAR PRO-CALCIFIC EFFECTS OF LEUKEMIA INHIBITORY FACTOR

Abstract Background and Aims Hyperphosphatemia in chronic kidney disease (CKD) is closely linked to medial vascular calcification. Phosphate is able to induce pro-inflammatory effects in vascular smooth muscle cells (VSMC), which could actively augment calcification processes. This study investigated the role of the IL-6 family member leukemia inhibitory factor (LIF) during vascular calcification. Method Experiments were performed in primary human aortic VSMCs, ex vivo mouse aortic rings and cholecalciferol treated mice, as well as serum samples from CKD patients and healthy controls. Results Phosphate exposure induced LIF release in VSMCs, while supplementation of LIF aggravated calcification and expression of pro-calcific markers in VSMCs. Silencing of LIF or addition of soluble LIF receptor (LIFR) as putative LIF antagonist ameliorated the pro-calcific effects of phosphate. Similarly, effects of phosphate or LIF were blunted by silencing of LIFR or its coreceptor GP130 in VSMCs. Mechanistically, LIF induced phosphorylation of TYK2, which was required for STAT1/3 activation. TYK2 overexpression augmented VSMC calcification, while silencing of either TYK2 or STAT1/3 ameliorated phosphate- and LIF-induced expression of pro-calcific markers. Pharmacological inhibition of TYK2 ameliorated calcification in VSMCs, mouse aortic rings and mice after cholecalciferol treatment. Furthermore, calcification was ameliorated in TYK2-deficient mouse aortic rings and mice after cholecalciferol overload. In a pilot study, LIFR was reduced in serum from patients with CKD and LIFR levels were associated with serum calcification propensity. Conclusion Vascular calcification is augmented by LIF, which identifies a crucial role of TYK2 in the pro-calcific reprogramming of VSMCs. Inhibition of this signalling axis might be able to reduce the burden of vascular calcification in CKD.