AB0040 JAK INHIBITORS – BARICITINIB AND TOFACITINIB – MODULATE THE IN VITRO INFLAMMATORY AND ALTERNATIVE POLARIZATIONS OF MACROPHAGES

Background Macrophages are major effector cells in inflammatory rheumatisms such as Rheumatoid arthritis (RA) and Psoriatic arthritis (PsA). Depending on their microenvironment, especially cytokines content, they can display various phenotypes or “polarizations” described as inflammatory (in the presence of IFNγ or GM-CSF) or as alternative (in the presence of IL-4 or IL-10). These cytokines involve JAK/STAT signaling pathway, and their action is expected to be inhibited by JAK inhibitors (JAKi) developed in RA and PsA. How JAKi modulate polarization of macrophage, and whether this phenomenon explains the clinical benefit in RA and PsA is not fully understood. Objectives To evaluate whether JAKi modulate in vitro polarization of monocytes derived macrophages. Methods [Cell culture] CD14+ monocytes were isolated from healthy donors and differentiated as macrophages in the presence of M-CSF. Macrophages were then polarized as inflammatory macrophages (by LPS + IFNγ, or GM-CSF), or as alternative macrophages (by IL-4, or IL-10), in the presence or not of JAKi (500 nM): Baricitinib (JAK1/JAK2 specific), Tofacitinib (JAK1/JAK2/JAK3/Tyk2 specific). [Membrane markers] Surface polarization markers were evaluated by flow cytometry. [Functional assays] Cytokines production in supernatants of macrophages were quantitated by bead-based immunoassay and by ELISA. Reactive oxygen species (ROS) production triggered by LPS and/or IFNγ was assessed by flow cytometry. Phagocytosis of E.coli bioparticles was assessed by flow cytometry. Results We analyzed 12 donors. Membrane polarization markers were: CD40/CD80/CD206 for inflammatory macrophages, CD163/CD16/CD206/CD200R for alternative macrophages. Both JAKi modulated these markers. Regarding the inflammatory polarizations, Baricitinib and Tofacitinib respectively reduced CD40 and CD206 expression. Regarding the alternative polarizations, both drugs inhibited the expression of CD163, CD206 and CD200R. At thecytokines level, both drugs did not significantly modulate the pro-inflammatory/anti-inflammatory balance in supernatants. We observed a slight increase in TNF and IL-6 resulting from LPS/NFkB pathway [1]. However, Baricitinib decreased the inflammatory IP-10, and increased IL-10 production. Both JAKi did not affect ROS production in the presence of LPS. Consistently with the absence of modulation of CD16 surface expression, Baricitinib and Tofacitinib did not affect CD16-dependent phagocytosis. Conclusion Our study shows that despite distinct JAK specificity, Tofacitinib and Baricitinib maintained surface phenotypes close to those of non-activated macrophages This finding was observed whatever was the polarizing condition, thus supporting the potential benefit of JAK inhibitors in different immune diseases. References [1] Pattison MJ, J Immunol, September15, 2012, 189 (6) 2784-2792 Disclosure of Interests Marion Magnol: None declared, Benjamin Rauwel: None declared, Souraya Sayegh: None declared, Katy Diallo: None declared, Michel Baron: None declared, Emmanuelle Lacassagne: None declared, Jean-Frederic Boyer: None declared, Adeline Ruyssen-Witrand: None declared, Arnaud Constantin: None declared, Jean-Luc Davignon Grant/research support from: Pfizer Passerelle Grant, Yannick Degboe Grant/research support from: Celgene PARTNER Fellowship