A bacterial protease inhibitor delivered subcutaneously limits APCs lysosomal proteolysis and increases immunogenicity of co-administered Ag

CORIA, LORENA; ANDRÉS E. IBAÑEZ; CARAVAJAL MARIANELA; BERGUER PAULA; LAURA BRUNO; GABRIELA RISSO; PAULA L. GONZALEZ COBIELLO; FERNANDA M. FRANK; KARINA A. PASQUEVICH; CASSATARO JULIANA

Congreso; Simposio; Keystone Symposia "The Modes of Action of Vaccine Adjuvants"; 2014; 2014

 Ourprevious results demonstrated that a Brucellaspp. protein (Bp) is a broad spectrum protease inhibitor as it can inhibitproteases present in the stomach and gut (mostly serine proteases). In this workwe demonstrated that Bp also possesses inhibitory activity on lysosomal proteases(cysteine proteases). Bp partially reduced the proteolytic activity ofcommercial cysteine proteases in vitro (P<0.01). Inhibition mechanism of Bp on cysteine proteases was characterizedusing a specific fluorogenic substrate for cathepsin L indicating that Bp is acompetitive inhibitor of cathepsin L with an inhibition constant in the µMrange. Also, Bp was able to inhibit Ag degradation by antigen presenting cells(APCs) increasing Ag half life and promoting its cross presentation (P<0.05). Bp inflammatory propertieswere also analyzed. After subcutaneous administration, Bp increased therecruitment of APCs to draining lymph nodes (P<0.01). Furthermore, Bp induced the up-regulation ofco-stimulatory molecules and secretion of pro-inflammatory cytokines from DCs in vitro. Moreover, subcutaneousco-administration of Bp as adjuvant and ovalbumin (OVA) as model antigen (Ag)induced OVA specific IFN-γproducing CD8+ T cells and cytotoxic T cells.  Finally, the adjuvant capacity of Bp invaccine formulations using real microbial derived Ags was studied using a wholehomogenate of Trypanosoma cruzi parasites(WH). Subcutaneous co-administration of Bp with WH reduced parasite loads andincreased survival after T. cruziinfection in mice (P<0.05).Altogether, these results indicate that Bp behaves as an ideal component invaccine formulations against infectious diseases.