Cloning and characterization of recombinant rhesus macaque IL-10/Fcala-ala fusion protein: A potential adjunct for tolerance induction strategies

The powerful anti-inflammatory and immunosuppressive activities of IL-10 make it attractive for supplemental therapy in translational tolerance induction protocols. This is bolstered by reports of IL-10-mediated inhibition of innate immunity, association of human stem cell and nonhuman primate (NHP) islet allograft tolerance with elevated serum IL-10, and evidence that systemic IL-10 therapy enhanced pig islets survival in mice. IL-10 has not been examined as adjunctive immunosuppression in NHP. To enable such studies, we cloned and expressed rhesus macaque (RM) IL-10 fused to a mutated hinge region of human IgG1 Fc to generate IL-10/Fcala-ala. RM IL-10/Fcala-ala was purified to ∼98% homogeneity by affinity chromatography and shown to be endotoxin-free (<0.008 EU/μg protein). The biological activity of IL-10/Fcala-ala was demonstrated by (1) costimulation of the mouse mast cell line, MC/9 proliferation in a dose-dependent fashion, (2) suppression of LPS-induced septic shock in mice and (3) abrogation of LPS-induced secretion of proinflammatory cytokines/chemokines in vitro and in vivo in NHP. Notably, RM IL-10/Fcala-ala had significantly greater potency than human IL-10/Fcala-ala and exhibited a circulating half-life of ∼14 days. The availability of this reagent will facilitate definitive studies to determine whether supplemental therapy with RM IL-10/Fcala-ala can influence tolerance outcomes in NHP.