Avaliação do efeito enteroprotetor de dez linhagens de Lactiplantibacillus plantarum em modelo murino de infecção induzida por Salmonella Typhimurium

Abstract

Salmonella Typhimurium is one of the leading causes of non-typhoid salmonellosis (NTS) in humans, a type of acute gastroenteritis that causes abdominal pain, vomiting, diarrhea, and nausea, with about 93.8 million global cases. The main therapeutic arsenal against NTS is the use of antibiotics; however, the use of these antimicrobials contributes to the emergence of multidrug-resistant strains. In this context, the use of probiotic microorganisms for developing alternative therapies represents a promising strategy due to their anti-inflammatory and antioxidant properties in the gastrointestinal tract and ability to inhibit pathogenic microorganisms. From previous in vitro studies, our research group identified ten strains of Lactiplantibacillus plantarum with inhibitory potential against S. Typhimurium. Based on these findings, the objective of this work was to evaluate the enteroprotective effect of these strains against S. Typhimurium infection in a murine model. Therefore, BALB/c mice received treatment with each of the ten Lpb. plantarum strains for 30 days, and on the 10th day, the animals were infected with S. Typhimurium. In this first stage, only the mortality rate was evaluated, in which it was observed that the treatments with the Lpl 4, Lpl 9, and Lpl 19 strains presented the highest survival rates: 70%, 80%, and 20%, respectively. Based on these results, these strains were selected to investigate their effects on clinical signs, secretory IgA levels, inflammatory infiltrate, histopathological analysis, and degree of bacterial translocation. From the data obtained, it was impossible to observe any significant effect on the parameters evaluated, except the Lpl 9 strain that prevented splenomegaly and the Lpl 19 strain that reduced weight loss in challenged mice. As a complementary analysis of this study, the antimicrobial activity of seven strains was evaluated through in vitro adhesion (coaggregation) and inhibition using the supernatant. The in vitro coaggregation assays demonstrated the presence of adhesion in five strains, Lpl 4, Lpl 9, Lpl 11, Lpl 14, and Lpl 20. Lpl 9 is the strain with the highest rate of coaggregation (55%) and whose supernatant showed better inhibition activity (53.6%) after pH neutralization. Therefore, the results obtained showed, that strains of Lpb. plantarum has microbicidal properties against Salmonella sp., and Lpl 9 and Lpl 4 were the most promising in treating salmonellosis in an in vivo model. However, further investigations are required to elucidate the probiotic mechanisms used by these strains.