Evaluation of the immunostimulant effect of microvesicles of Lactobacillus acidophilus isolated from wild Rattus norvegicus.

Lactic acid bacteria are components of the microbiota of the gastrointestinal tract in both humans and animals and are widely used as probiotics. The bacterial strain Lactobacillus sp. is the most related to probiotic activity and released membrane microvesicles (MVs). Some of their primary functions are to carry and transmit antigens to the host tissues and modulate the host defense responses. In the present study, Lactobacillus acidophilus was isolated from the ileum of free-living Rattus norvegicus to evaluate the immunostimulant effect of their MVs in two biological models. MVs from L. acidophilus were characterized using sodium dodecyl sulfate-polyacrylamide gel electrophoresis, electron microscopy, and nanoparticle tracking analysis. The immunostimulant effect of MVs from L. acidophilus on ovine abomasal explants, previously stimulated with 30 µg/1h of MVs and subsequently challenged with third-stage larvae (L3) of Haemonchus contortus, was probed, demonstrating a decrease in the percentage of larvae association, and favoring the migration of inflammatory cells to the infection site. In contrast, cells line of the RAW 264.7 were stimulated by 10 µg/3h of MVs from L. acidophilus to evaluate their activation through the expression of transcripts coding for IL-1β and TNF-α. In both cases, the immunostimulatory effects of MVs from L. acidophilus isolated from free-living R. norvegicus were verified, demonstrating that these structures are capable of immunostimulated the evaluated biological models and could carried important antigen that can be considerate in a formulation to promote the intestinal health in livestock production.  The present study is the first report of MVs secreted by L. acidophilus isolated from free-living R. norvegicus caring that this rodent is resistant to many bacterial pathogens that normally affect the gastrointestinal tract of other mammals.

In the atachment file we present the data obtained of the porcentage of asocciation and porcentage of mortality of L3 stage larvae from H. contortus in abomasal tissue stimulated with microvesicles from L. acidophilus. In the other hand the expression of IL-1β and TNFα.  mRNA from RAW 264.7 cells stimulated with microvesicles from L. acidophilus.