RESUMEN
The objective of the present study was to find an explanation for the biological effect of the bacteria present in a biotherapeutic milk (Lactobacillus casei CRL 431 and Lactobacillus acidophilus CRL 730). The ability of bacterial cell walls to induce an immune response when introduced into an organism is well known. In this paper we specifically analyzed the morphology of these cell walls. Besides the two bacterial strains used in the fermented milk, two other lactic acid bacteria, belonging to another genus and unable to induce an immune system response, as well as a strain of Propionibacterium, of which the immune modulating capacity is known, were used in this work. We found a structural particularly in strains with immunostimulating capacity (L. casei CRL 431 and P. acidopropionici CRL 1198): molecules which protrude from the cell surface. In L. casei CRL 431 these molecules were identified as lectins because they are able to agglutinate yeast cells treated with glutaraldehyde and glycine. The structures protruding from P. acidipropionici CRL 1198 cells were teichoic acids. Teichoic acid and lectin-like structures can participate in adhesion to intestinal cells. The immunostimulation observed can be induced by the adhesion phenomenon.
Asunto(s)
Proteínas Bacterianas/inmunología , Pared Celular/inmunología , Lacticaseibacillus casei/inmunología , Lactobacillus acidophilus/inmunología , Propionibacterium/inmunología , Adyuvantes Inmunológicos/farmacología , Pruebas de Aglutinación , Animales , Bilis/microbiología , Adhesión Celular/efectos de los fármacos , Pared Celular/ultraestructura , Intestinos/efectos de los fármacos , Lactobacillus acidophilus/ultraestructura , Lacticaseibacillus casei/ultraestructura , Lectinas , Proteínas de la Membrana/inmunología , Leche/microbiología , Propionibacterium/ultraestructura , Ácidos Teicoicos/farmacologíaRESUMEN
Attempts to achieve IgA responses in the intestine by oral immunization with non replicating antigens have been characterized by ineffective responses of short duration unless long term dosages are administered. Cholera toxin (CT) is an exception in that it is able to produce a high secretory and systemic immune response. We study the effects of a bacterial immunomodulator [3 x 10(10) Propionibacterium granulosum ml-1 and lipopolysaccharide (LPS) 5 mg ml-1] on the immune response to CT orally administered to Wistar rats. The immunomodulator was orally administered as follows: in schedule 1 during 7 days prior to the first dose of CT; and in schedule 2, 2 days before, together, and 3 days after the first dose of CT. Schedules 1 and 2 were effective in increasing the specific IgA in the intestinal fluid and specific IgG in serum (P < 0.001) when compared to controls. Besides, schedule 2 was more effective than schedule 1 when the levels of specific IgG in serum or specific IgA in intestinal fluid was measured (P < 0.05). Total IgA in the intestinal fluid was increased in rats receiving the immunomodulator (P < 0.01). However, the ratio of specific IgA per total IgA was higher in rats receiving treatment 1 or 2 when compared to controls (P < 0.01). The number of antitoxin antibody producing cells was not increased in the Peyer patches, but a significant increase was observed in the mesenteric lymph nodes and spleen when compared to controls (P < 0.05). The administration of LPS alone produced an increase in the antitoxin immune response when compared to controls, but it was lower than those produced by the administration of the immunomodulator. These results indicate that this immunomodulator is an effective adjuvant of the mucosal and systemic immune response to CT. The mechanisms of action possibly involve nonespecific and specific modulations of the immune response.