EFFECT OF CO-ADMINISTRATION OF LACTOBACILLI S-LAYER PROTEINS ON IMMUNE RESPONSE AGAINST S-LAYER PROTEINS FROM PATHOGENIC CLOSTRIDIOIDES DIFFICILE

ASSANDRI MH; FITA M; TREJO FM; SERRADELL MA

San Luis

Congreso; LXXI Reunión Anual de SAI; 2023

Sociedad Argentina de Inmunología

The anaerobic, Gram-positive, spore-forming pathogen Clostridioides difficile is one of the leading causes of nosocomial antibiotic-associated diarrhoea (AAD) worldwide. Active immunization with surface components or sporulation factors emerges as an alternative to the antibiotic-based therapy. The S-layer is a twodimensional self-assembled (glyco)-proteinaceous envelope covering the surface of several pathogenic and non-pathogenic bacteria. Previously, we have shownthat glycosylated S-layer proteins (SLPs) from different strains of Lentilactobacillus kefiri enhance LPS-induced stimulation in murine macrophages. Moreover, it has been reported that C. difficile SLPs could act as a Toll-like receptor 4 ligand. Thus, with the aim to find new C. difficile antigenictargets and potential adjuvants, we started our study assessing the ability of SLPs derived from C. difficile ATCC 43255 (SLP-Cd), and the SLPs of different L. kefiri strains (SLP-Lk8335, SLP-Lk8343, SLP-Lk8344, SLP-Lk83111, SLP-Lk83113) to activate murine macrophages in vitro both alone and combined. Cultured RAW264.7 cells were treated with individual SLPs or a combination of SLP-Lk +SLP-Cd, and secreted IL-6 after 24h of stimulation was measured by capture ELISA. SLP-Cd did not exert a strong stimulus on macrophage even when were tested at 30 mg/ml. On the other hand, only SLP-Lk8343 and SLP-Lk83111 were able to stimulate IL-6 secretion on RAW264.7 cells at 10 mg/ml (P< 0,05). Interestingly, cellular activation was significantly increased (P