Biomedical subjects

Alfonso Ruiz-Bravo

Publications and source records attributed to Alfonso Ruiz-Bravo.

7 recordsLinked to original sources

PubMed2006

A selective differential medium for Lactobacillus plantarum.

The quantification of exogenous lactobacilli in faecal samples is frequently required for the evaluation of the intestinal colonization by probiotic bacteria. In this study, a selective and differential medium, designated LPSM, was developed for the culture of exogenous Lactobacillus plantarum. In quantitative assays, LPSM showed a sensitivity similar to those of enriched and Lactobacillus-adapted media. The presence of ciprofloxacin made LPSM inhibitory to most intestinal bacteria, including endogenous acid lactic bacteria, whereas exogenous L. plantarum strains grew producing a yellow color caused by acid production from sorbitol in the presence of bromocresol purple. The results showed that LPSM is suitable for detection and enumeration of L. plantarum in faecal samples.

Animals↗

PubMed2005

Immunomodulation by non-absorbable antibiotics given by the intragastric route.

To test the role of bacterial fractions released from intestinal flora during immunomodulation by antimicrobial agents, BALB/c mice were treated with the non-absorbable antibiotics polymyxin B or teicoplanin by the intragastric route. The composition of faecal microbiota and the capacity of spleen cells to proliferate in response to B-cell and T-cell mitogens were assessed at several times during the treatment. Both antibiotics lowered the count of some bacteria of the intestinal flora and induced significant modifications in spleen cell ability to proliferate in response to mitogens. Thus, the active fractions released from intestinal bacteria during antibiotic treatments may be able to induce immunomodulating effects.

Animals↗

PubMed2004

In vivo immunomodulation by Mycoplasma fermentans membrane lipoprotein.

The immunomodulatory effects of Mycoplasma fermentans-derived membrane lipoprotein (LAMPf) in BALB/c mice were examined. When injected intraperitoneally into mice, LAMPf induced a transitory splenomegaly followed by a suppression of the spleen cell proliferation in response to concanavalin A, whereas responses to lipopolysaccharide and to LAMPf were unchanged. The intravenous injection of a large dose of LAMPf induced leukopenia and granulocyte-macrophage colony-stimulating factor (GM-CSF) activity in serum. A synthetic analogue of its N-terminal lipopeptide with ability to activate macrophages (MALP-2) was also able to induce GM-CSF in serum. Interestingly, GM-CSF induction by a low dose of MALP-2 was not associated with significant leukopenia. These data revealed that the in vitro moduline properties of mycoplasmal lipoproteins and lipopeptides correlate with interesting in vivo immunomodulatory effects.

Animals↗

PubMed2004

Lack of apoptosis in Listeria monocytogenes-infected thymocytes from mice fed with dietary lipids.

The potential action of certain fatty acids has been studied since the early 1970s. Numerous effects on immune system functions have been related to dietary lipid administration; therefore, several of them have been applied in the treatment of inflammatory disorders. Nevertheless, n-3 polyunsaturated fatty acids may affect host resistance to infectious diseases. In addition, several studies have demonstrated that certain fatty acids are involved in apoptosis induction. Here, we have examined the action of different dietary lipids on the promotion of apoptosis in thymocytes from mice fed with dietary lipids and infected with Listeria monocytogenes. Thus, L. monocytogenes promoted an important cytotoxic effect in all of the groups, but it did not increase the percentage of DNA fragmentation. Similarly, an important increase of caspase-3 activity was demonstrated in OO and FO groups, but infection with L. monocytogenes exerted an inhibitory effect. Finally, L. monocytogenes did not modify proteasome activity among groups fed with dietary lipids. On the basis of this preliminary study, we can state that the infection of thymocytes from mice fed with dietary lipids does not promote a synergistic effect in the induction of apoptosis. Hence, these results may partially serve to elucidate the immune mechanisms involved in cells from mice fed with dietary lipids in an infectious process.

Animals↗

PubMed2004

Changes in the immune functions and susceptibility to Listeria monocytogenes infection in mice fed dietary lipids.

The direct examination of the effects that fish oil diets (composed of long-chain n-3 polyunsaturated fatty acids) exert on immune system function indicates a reduction of host natural resistance to infectious diseases mainly because of a suppression of immune function generated by the fatty acids contained in this diet. Here, we evaluated the concentration of IL-12, IL-4, prostaglandin E2 and leukotriene B4 in the serum from BALB/c mice receiving four different diets. Each group was fed a diet that differed only in the source of fat: a low-fat diet (2.5% by weight), an olive oil diet (20% by weight), a fish oil diet (20% by weight) or a hydrogenated coconut oil diet (20% by weight). Mice were fed for 4 weeks and then infected with the intracellular pathogen Listeria monocytogenes. An initial reduction in the Th1-type response as a result of a decrease in IL-12p70 secretion, an inefficient action of IL-4 (Th2-type response) and no modification of pro-inflammatory lipid-mediator production could be, at least in part, the key events responsible for the inadequate elimination of L. monocytogenes from the spleens of mice fed a fish oil diet. Furthermore, our results suggest that the type of dietary lipids may affect the circulating concentration of IL-12p70 and IL-4, leading to a modulation in the protective cellular immune response to L. monocytogenes infection.

Animals↗

PubMed2003

Immunomodulation by Yersinia enterocolitica: comparison of live and heat-killed bacteria.

This study compared the immunomodulating properties of viable and killed Yersinia enterocolitica O9 in BALB/c mice. At 10 days after infection by the intragastric route, ex vivo assays showed a suppression of spleen cell proliferation in response to Salmonella lipopolysaccharide, concanavalin A and heat-killed yersiniae. Mice infected with Y. enterocolitica O9 for 10 days resisted the challenge with a lethal dose of Listeria monocytogenes. In contrast, intravenous administration of heat-killed yersiniae did not modify the ability of spleen cells to proliferate in response to lipopolysaccharide or concanavalin A, and proliferation in response to killed yersiniae was significantly increased. By 3 days after administration of a single dose of heat-killed yersiniae, the resistance of mice to L. monocytogenes challenge was significantly increased. Our findings show profound differences in immunomodulation by viable and heat-killed yersiniae, but suggest that killed yersiniae retain interesting immunomodulating properties.

Animals↗

PubMed2003

Modification of mitogen-driven lymphoproliferation by ceftriaxone in normal and immunocompromised mice.

Cyclophosphamide-treated mice are proposed as a model to assay immunomodulation by antimicrobial agents in immunocompromised animals. Cyclophosphamide-treated BALB/c mice developed temporary leukopenia, myelopenia and spleen atrophy that was followed by splenomegaly. Cells from both atrophic and hypertrophic spleens exhibited impaired responses to mitogens and suppressed the mitogen-driven proliferation of normal splenocytes. This experimental model was applied to the study of immunomodulation by ceftriaxone. Ceftriaxone did not worsen the cyclophosphamide-damaged immunity mechanisms. On the contrary, cyclophosphamide-induced suppression of lymphoproliferation in response to concanavalin A was attenuated by ceftriaxone.

Adjuvants, Immunologic↗