IMPACT OF JAK INHIBITORS ON MACROPHAGE POLARISATION: PERSPECTIVES FOR SYSTEMIC SCLEROSIS

Background: Macrophage can adopt various phenotypes and activation states according to their surrounding microenvironment. M1 or inflammatory macrophages are generated under IFNɣ/LPS signaling and express the membrane marker CD86. Different subtypes of M2 macrophages are also described: M2a macrophages (generated under IL4/IL13 signaling) and characterized by a high expression of CD206 and pro-fibrotic properties and, M2c macrophages (generated under IL10 and/or glucorticoid signaling), considered as anti-inflammatory resolving macrophages. There is growing interest in the role of macrophages in the pathogenesis of Systemic Sclerosis (SSc). Recent studies highlight that macrophages from fibrotic tissues such as lung or skin from SSc patients have a M2 phenotype whereas, in blood-monocytes derived macrophages (MDM), SSc MDM have a mixed signature associating M1 and M2 characteristics. Jak inhibitors are treatments used in rheumatoid arthritis and that can variously target signals that could be involved both in M1 and in M2 polarisation. Objectives: This study evaluates the impact of three Jak inhibitors on the polarisation state of human MDM in vitro. Methods: Blood monocytes form healthy donors (HD) were differentiated with M-CSF (for 7 days) in MDM and pre-treated by ruxolitinib (Jak2-Jak1 inhibitor), tofacitinib (Jak3 inhibitor) or itacitinib (Jak1 inhibitor) (1µM for all). They were then polarised into M1i (IFNɣ, 20µg/mL), M1Li (IFNɣ+LPS, 20µg/mL), M2a (IL4+IL13; 20µg/ML), M2c (IL10, 20µg/mL) and M2c(dex) (IL10+dexamethasone, 10 nM). The impact of each Jak inhibitor on phenotype (flow cytometry), gene expression (qPCR) and cytokine secretion (ELISA) was evaluated in each polarisation state. Results: Concerning phenotypes, all Jak inhibitors reduced the expression of the M1i and M1Li marker CD86, but ruxolitinib had a higher effect. Only ruxolitinib reduced the expression of the M1i marker MHCII. All Jak inhibitors reduced the expression of CD206 in M2a. They had no impact on the expression of CD163, CD204 in any M2 conditions. Key M1 genes were repressed by all Jak inhibitors, such as CXCL10, IL6 or TNFα with a more significant effect of ruxolitinib. All Jak inhibitors reduced the gene expression of CXCL13 and SOCS3 in M2c. Secretion levels of IL6 and CCL18 were also repressed, with a more significant effect of ruxolitinib. Conclusion: Jak inhibitors can limit M1 and M2 polarisation state in vitro, with a more significant effect of the Jak2-Jak1 inhibitor ruxolitinib. The relevance of these results in MDM from SSc patients and in vivo models of SSc is still to be determined. Disclosure of Interests: Alain LESCOAT: None declared, Alice Ballerie: None declared, Marie Lelong: None declared, Claudie Morzadec: None declared, Stephane Jouneau Grant/research support from: AIRB, Boehringer Ingelheim, LVL Medical, Novartis, Roche, Bellorophon Therapeutics, Biogen, Fibrogen, Galecto Biotech, Gilead Sciences, Pharm-Olam, Pliant Therapeutics, Savara Pharmaceuticals/Serendex Pharmaceuticals, Consultant of: Actelion, AIRB, AstraZeneca, Bristol-Myers Squibb, Boehringer Ingelheim, Chiesi, Genzyme, GlazoSmithKline, LVL Medical, Mundipharma, Novartis, Pfizer, Roche, Sanofi, Patrick Jego: None declared, Laurent Vernhet: None declared, Olivier Fardel: None declared, Valerie Lecureur: None declared