“Immunomodulation of raw 264.7 macrophages by Bacillus lipopeptide extracts upon LPS challenge and evaluation of their antimicrobial activity against swine enteric pathogens

DI GIACOMO, A.L; AZCURRA L.N.; GARCÍA, G; DOGI C; GONZÁLEZ PEREYRA M.L

Jornada; LXXI Reunión Científica Anual de la Sociedad Argentina de Inmunología; 2023

Weaning is a stressful period in swine production where susceptibility topathogens such as enterotoxigenic Escherichia coli (ETEC) and SalmonellaTyphimurium causing post-weaning diarrhea (PWD). The aim of the present studywas to explore the potential of Bacillus lipopeptide extracts (LPE) naturallycontaining surfactin (SF) – a lipopeptide with anti-inflammatory and antimicrobialcapacity, among other biological activities – to mitigate PWD by assessing theirimmunomodulatory and antimicrobial effects. LPE were obtained from Bacillusspp. isolated from bovine feces and soil and their SF concentration quantified byRP-HPLC. LPE’s effect on RAW 264.7 murine macrophages viability wasassessed by an MTT-based assay. Cytokines (TNF-α; IFN-Υ; IL-10) and NOproduction after LPS challenge was measured in RAW 264.7 cells pre-treatedwith LPE and untreated control cells. Effect of LPE on macrophages phagocyticand microbicidal capacity was also assessed pre-treating RAW 264.7 cells withextracts containing 0.01 to 60 μg/ml SF. Minimal inhibitory concentration (MIC)and minimal bactericidal concentration (MBC) of LPEs against ETEC andSalmonella Typhimurium were calculated. LPE from Bacillus spp. isolates MFF2.2 and TC12, containing 40 and 60 μg/ml of SF showed a significant (p