OR17-03 Vasoinhibin Analogs Vi45-51 And Crivi45-51 Lack The Proinflammatory Properties Of Vasoinhibin In Arthritis

Abstract Disclosure: G. Ortiz: None. J.F. García Rodrigo: None. O.F. Martínez-Díaz: None. J.P. Robles: None. M. Zamora: None. X. Ruiz-Herrera: None. E.A. de Los Ríos: None. G. Martinez de la Escalera: None. C. Clapp: None. Vasoinhibin, a fragment of prolactin, has dual actions on inflammatory arthritis. It reduces joint inflammation by the inhibition of pannus vascularization (1) but enhances arthritis by direct proinflammatory effects on synovial fibroblasts (2). Linear (Vi45-51) and cyclic (CRIVi45-51) heptapeptides comprising the 45 to 51 amino acids of vasoinhibin conserve the antiangiogenic effects and potency of whole vasoinhibin, but are easier to produce, stable, and orally active to be developed for clinical use (3). In view of their therapeutic potential in arthritis, we investigated whether Vi45-51 and CRIVi45-51 conserved the proinflammatory effects of vasoinhibin in joint tissues. Synovial fibroblasts (SF) isolated from the knee joint of male C57BL/6 mice were incubated with or without recombinant vasoinhibin of 123 amino acids (positive control), Vi45-51, or CRIVi45-51. As expected, vasoinhibin upregulated the expression of tumor necrosis factor-α (TNF-α) and inducible nitric oxide synthase (iNOS) and increased the production of nitric oxide (NO) in SF. However, similar or higher concentrations of Vi45-51 and CRIVi45-51 were inactive. The lack of inflammatory properties suggested improved efficacy of antiangiogenic Vi45-51 and CRIVi45-51 in arthritis. The antigen-induced arthritis (AIA) mouse model was carried out under severe [20 μg of intra-articular administration of methylated serum albumin (mBSA) as antigen] and mild (2.5 μg mBSA) inflammatory conditions to detect the antiangiogenic and proinflammatory effects of vasoinhibin, respectively (2). Consistent with its antiangiogenic properties, intra-peritoneal injection of CRIVi45-51 reduced joint swelling and pannus formation/vascularization in male C57BL/6 mice subjected to severe AIA. Moreover, in agreement with lack of proinflammatory actions, CRIVi45-51 did not elevate joint swelling under mild AIA. We conclude that Vi45-51 and CRIVi45-51 are beneficial in arthritis due to their antiangiogenic properties and lack of proinflammatory actions. Vasoinhibin analogs may be good therapeutic alternatives in inflammatory arthritis, including rheumatoid arthritis. Supported by CONACYT (A1-S-9620B) and UNAM (DGAPA-PAPIIT IN202321). Reference: (1) Ortiz et al., Lab Invest. 2020 Aug;100(8):1068-79. (2) Ortiz et al., Endocrinology 2022 May;163(5): bqac036. (3) Robles et al., Angiogenesis 2022 Feb;25(1):57-70. Presentation: Saturday, June 17, 2023