Effect of probiotics on glucose levels and weight gain in mice exposed to low doses of malathion.

INTRODUCTION: Owing to its ability to reduce the toxicity of environmental pollutants that are risk factors for diabetes and obesity, the use of probiotic bacteria might aid the treatment of these diseases. OBJECTIVE: To determine the effects of chronic exposure to low-dose malathion on weight and glucose levels in mice, as well as to evaluate the protective role of a probiotic supplement. METHODS: Weight and serum glucose levels of four groups of mice (control, malathion-exposed [10 ppm], probiotics and malathion + probiotics) were determined every 10 days for 180 days. RESULTS: Malathion administration induced an increase in weight and glucose levels in the malathion group mice in comparison with the other groups. CONCLUSIONS: Consumption of food contaminated with malathion residues increases glucose levels and favors weight gain, while consumption of probiotics reduces the effects generated by residues in food.

INTRODUCCIÓN: Debido a su capacidad para reducir la toxicidad de contaminantes ambientales que constituyen factores de riesgo de diabetes y obesidad, el uso de bacterias probióticas podría ayudar al tratamiento de esas enfermedades. OBJETIVO: Determinar los efectos de la exposición crónica a malatión a dosis bajas sobre el peso y los niveles de glucosa de ratones, así como evaluar el papel protector de un suplemento probiótico. MÉTODOS: Cada 10 días se determinó el peso y la glucosa sérica de cuatro grupos de ratones (de control, expuestos a malatión (10 ppm), probióticos y malatión + probióticos) durante 180 días. RESULTADOS: La administración de malatión provocó un incremento del peso y los niveles de glucosa en los ratones del grupo con malatión comparados con los demás grupos. CONCLUSIONES: El consumo de alimentos contaminados con residuos de malatión aumenta los niveles de glucosa y favorece el incremento del peso; el consumo de probióticos disminuye los efectos generados por los residuos en los alimentos.

Efecto de los probióticos en los niveles de glucosa y el incremento de peso en ratones expuestos a dosis bajas de malatión / Effect of probiotics on glucose levels and weight gain in mice exposed to low doses of malathion

Resumen Introducción: Debido a su capacidad para reducir la toxicidad de contaminantes ambientales que constituyen factores de riesgo de diabetes y obesidad, el uso de bacterias probióticas podría ayudar al tratamiento de esas enfermedades. Objetivo: Determinar los efectos de la exposición crónica a malatión a dosis bajas sobre el peso y los niveles de glucosa de ratones, así como evaluar el papel protector de un suplemento probiótico. Métodos: Cada 10 días se determinó el peso y la glucosa sérica de cuatro grupos de ratones (de control, expuestos a malatión (10 ppm), probióticos y malatión + probióticos) durante 180 días. Resultados: La administración de malatión provocó un incremento del peso y los niveles de glucosa en los ratones del grupo con malatión comparados con los demás grupos. Conclusiones: El consumo de alimentos contaminados con residuos de malatión aumenta los niveles de glucosa y favorece el incremento del peso; el consumo de probióticos disminuye los efectos generados por los residuos en los alimentos.

Abstract Introduction: Owing to its ability to reduce the toxicity of environmental pollutants that are risk factors for diabetes and obesity, the use of probiotic bacteria might aid the treatment of these diseases. Objective: To determine the effects of chronic exposure to low-dose malathion on weight and glucose levels in mice, as well as to evaluate the protective role of a probiotic supplement. Methods: Weight and serum glucose levels of four groups of mice (control, malathion-exposed [10 ppm], probiotics and malathion + probiotics) were determined every 10 days for 180 days. Results: Malathion administration induced an increase in weight and glucose levels in the malathion group mice in comparison with the other groups. Conclusions: Consumption of food contaminated with malathion residues increases glucose levels and favors weight gain, while consumption of probiotics reduces the effects generated by residues in food.

The Assembly of Flagella in Enteropathogenic Escherichia coli Requires the Presence of a Functional Type III Secretion System.

In enteropathogenic Escherichia coli (EPEC), the production of flagella and the type III secretion system (T3SS) is activated in the presence of host cultured epithelial cells. The goal of this study was to investigate the relationship between expression of flagella and the T3SS. Mutants deficient in assembling T3SS basal and translocon components (ΔespA, ΔespB, ΔespD, ΔescC, ΔescN, and ΔescV), and in secreting effector molecules (ΔsepD and ΔsepL) were tested for flagella production under several growth conditions. The ΔespA mutant did not produce flagella in any condition tested, although fliC was transcribed. The remaining mutants produced different levels of flagella upon growth in LB or in the presence of cells but were significantly diminished in flagella production after growth in Dulbecco's minimal essential medium. We also investigated the role of virulence and global regulator genes in expression of flagella. The ΔqseB and ΔqseC mutants produced abundant flagella only when growing in LB and in the presence of HeLa cells, indicating that QseB and QseC act as negative regulators of fliC transcription. The ΔgrlR, ΔperA, Δler, Δhns, and Δfis mutants produced low levels of flagella, suggesting these regulators are activators of fliC expression. These data suggest that the presence of an intact T3SS is required for assembly of flagella highlighting the existence in EPEC of a cross-talk between these two virulence-associated T3SSs.

The Flp type IV pilus operon of Mycobacterium tuberculosis is expressed upon interaction with macrophages and alveolar epithelial cells.

The genome of Mycobacterium tuberculosis (Mtb) harbors the genetic machinery for assembly of the Fimbrial low-molecular-weight protein (Flp) type IV pilus. Presumably, the Flp pilus is essential for pathogenesis. However, it remains unclear whether the pili genes are transcribed in culture or during infection of host cells. This study aimed to shed light on the expression of the Flp pili-assembly genes (tadZ, tadA, tadB, tadC, flp, tadE, and tadF) in Mtb growing under different growth conditions (exponential phase, stationary phase, and dormancy NRP1 and NRP2 phases induced by hypoxia), during biofilm formation, and in contact with macrophages and alveolar epithelial cells. We found that expression of tad/flp genes was significantly higher in the stationary phase than in exponential or NRP1 or NRP2 phases suggesting that the bacteria do not require type IV pili during dormancy. Elevated gene expression levels were recorded when the bacilli were in contact for 4 h with macrophages or epithelial cells, compared to mycobacteria propagated alone in the cultured medium. An antibody raised against a 12-mer peptide derived from the Flp pilin subunit detected the presence of Flp pili on intra- and extracellular bacteria infecting eukaryotic cells. Altogether, these are compelling data showing that the Flp pili genes are expressed during the interaction of Mtb with host cells and highlight a role for Flp pili in colonization and invasion of the host, subsequently promoting bacterial survival during dormancy.

The EcpD Tip Adhesin of the Escherichia coli Common Pilus Mediates Binding of Enteropathogenic E. coli to Extracellular Matrix Proteins.

The attachment of enteropathogenic Escherichia coli (EPEC) to intestinal epithelial cells is facilitated by several adhesins; however, the individual host-cell receptors for pili-mediated adherence have not been fully characterized. In this study, we evaluated the hypothesis that the E. coli common pilus (ECP) tip adhesin protein EcpD mediates attachment of EPEC to several extracellular matrix (ECM) glycoproteins (fibronectin, laminin, collagens I and IV, and mucin). We found that the ΔecpA mutant, which lacks production of the EcpA filament but retains EcpD on the surface, adhered to these glycoproteins below the wild-type levels, while the ΔecpD mutant, which does not display EcpA or EcpD, bound significantly less to these host glycoproteins. In agreement, a purified recombinant EcpD subunit bound significantly more than EcpA to laminin, fibronectin, collagens I and IV, and mucin in a dose-dependent manner. These are compelling data that strongly suggest that ECP-producing EPEC may bind to host ECM glycoproteins and mucins through the tip adhesin protein EcpD. This study highlights the versatility of EPEC to bind to different host proteins and suggests that the interaction of ECP with the host's ECM glycoproteins may facilitate colonization of the intestinal mucosal epithelium.

The Fis Nucleoid Protein Negatively Regulates the Phase Variation fimS Switch of the Type 1 Pilus Operon in Enteropathogenic Escherichia coli.

In Escherichia coli the expression of type 1 pili (T1P) is determined by the site-specific inversion of the fimS ON-OFF switch located immediately upstream of major fimbrial subunit gene fimA. Here we investigated the role of virulence (Ler, GrlR, and GrlA) and global regulators (H-NS, IHF, and Fis) in the regulation of the fimS switch in the human enteropathogenic E. coli (EPEC) O127:H6 strain E2348/69. This strain does not produce detectable T1P and PCR analysis of the fimS switch confirmed that it is locked in the OFF orientation. Among the regulator mutants analyzed, only the ∆fis mutant produced significantly high levels of T1P on its surface and yielded high titers of agglutination of guinea pig erythrocytes. Expression analysis of the fimA, fimB, and fimE promoters using lacZ transcriptional fusions indicated that only PfimA activity is enhanced in the absence of Fis. Collectively, these data demonstrate that Fis is a negative regulator of T1P expression in EPEC and suggest that it is required for the FimE-dependent inversion of the fimS switch from the ON-to-OFF direction. It is possible that a similar mechanism of T1P regulation exists in other intestinal and extra-intestinal pathogenic classes of E. coli.

The Transcription of Flagella of Enteropathogenic Escherichia coli O127:H6 Is Activated in Response to Environmental and Nutritional Signals.

The flagella of enteropathogenic Escherichia coli (EPEC) O127:H6 E2348/69 mediate adherence to host proteins and epithelial cells. What environmental and nutritional signals trigger or down-regulate flagella expression in EPEC are largely unknown. In this study, we analyzed the influence of pH, oxygen tension, cationic and anionic salts (including bile salt), carbon and nitrogen sources, and catecholamines on the expression of the flagellin gene (fliC) of E2348/69. We found that sodium bicarbonate, which has been shown to induce the expression of type III secretion effectors, down-regulated flagella expression, explaining why E2348/69 shows reduced motility and flagellation when growing in Dulbecco's Minimal Essential Medium (DMEM). Further, growth under a 5% carbon dioxide atmosphere, in DMEM adjusted to pH 8.2, in M9 minimal medium supplemented with 80 mM glucose or sucrose, and in DMEM containing 150 mM sodium chloride, 0.1% sodium deoxycholate, or 30 µM epinephrine significantly enhanced fliC transcription to different levels in comparison to growth in DMEM alone. When EPEC was grown in the presence of HeLa cells or in supernatants of cultured HeLa cells, high levels (4-fold increase) of fliC transcription were detected in comparison to growth in DMEM alone. Our data suggest that nutritional and host signals that EPEC may encounter in the intestinal niche activate fliC expression in order to favor motility and host colonization.

The Two-Component System CpxRA Negatively Regulates the Locus of Enterocyte Effacement of Enterohemorrhagic Escherichia coli Involving σ(32) and Lon protease.

Enterohemorrhagic Escherichia coli (EHEC) is a significant cause of serious human gastrointestinal disease worldwide. EHEC strains contain a pathogenicity island called the locus of enterocyte effacement (LEE), which encodes virulence factors responsible for damaging the gut mucosa. The Cpx envelope stress response of E. coli is controlled by a two-component system (TCS) consisting of a sensor histidine kinase (CpxA) and a cytoplasmic response regulator (CpxR). In this study, we investigated the role of CpxRA in the expression of LEE-encoded virulence factors of EHEC. We found that a mutation in cpxA significantly affected adherence of EHEC to human epithelial cells. Analysis of this mutant revealed the presence of high levels of CpxR which repressed transcription of grlA and ler, the main positive virulence regulators of the LEE, and influenced negatively the production of the type 3 secretion system-associated EspABD translocator proteins. It is known that CpxR activates rpoH (Sigma factor 32), which in turns activates transcription of the lon protease gene. We found that transcription levels of ler and grlA were significantly increased in the lon and cpxA lon mutants suggesting that lon is involved in down-regulating LEE genes. In addition, the Galleria mellonella model of infection was used to analyze the effect of the loss of the cpx and lon genes in EHEC's ability to kill the larvae. We found that the cpxA mutant was significantly deficient at killing the larvae however, the cpxA lon mutant which overexpresses LEE genes in vitro, was unable to kill the larvae, suggesting that virulence in the G. mellonella model is T3SS independent and that CpxA modulates virulence through a yet unknown EHEC-specific factor. Our data provides new insights and broadens our scope into the complex regulatory network of the LEE in which the CpxA sensor kinase plays an important role in a cascade involving both global and virulence regulators.

Posibilidades etiológicas para el desarrollo de enfermedades reumáticas por mecanismos ambientales / Etiologic possibilities for the development of rheumatic diseases through environmental mechanisms

Los seres vivos y el medio que los sostiene tienen una interdependencia obligada; cualquier evento ocurrido dentro de un ecosistema afecta a todas sus fracciones. El enfoque del proceso salud-enfermedad reconoce las influencias del medio ambiente. Para enfermedades autoinmunitarias como el lupus eritematoso sistémico (LES) o generalizado se ha reconocido la posibilidad de que se produzca por luz ultravioleta y exposición al sol de manera prolongada. Los agentes microbianos pueden generar otras enfermedades como las artritis reactivas. Sustancias como la alfalfa son capaces de causar alguna enfermedad y los trabajadores de laboratorio que manipulan sueros de pacientes con enfermedades reumáticas autoinmunitarias se tornan positivos a los anticuerpos que están trabajando. Es así que las ciencias ambientales y el enfoque laboral permiten un nuevo abordaje para el estudio de los posibles mecanismos patogénicos en la aparición de algunas enfermedades reumáticas. Este artículo revisa las principales evidencias existentes y plantea algunas hipótesis generadas a partir de esa misma revisión (AU)

Living beings and the environment that supports them have a mutual interdependence and therefore any event that occurs within an ecosystem affects all parts. The influence that the environment has on subjects that may develop an illness has been amply recognized. For some autoimmune diseases such as systemic lupus erythematosus (SLE), the possibility of its development under ultraviolet light and prolonged exposure to sunlight has been recognized. Microorganisms may activate other illnesses such as reactive arthritis. Substances such as alfalfa are also able to unleash disease activity. Laboratory workers who manipulate sera of patients with autoimmune rheumatic disorders develop antibodies to the sera that they are working with. It is thus that environmental sciences and focused research allow the development of a new approach to the study of possible pathogenic mechanisms in the appearance of certain rheumatic disorders. This article reviews the main existing evidence and proposes certain hypotheses derived from it (AU)

[Etiologic possibilities for the development of rheumatic diseases through environmental mechanisms]. / Posibilidades etiológicas para el desarrollo de enfermedades reumáticas por mecanismos ambientales.

Living beings and the environment that supports them have a mutual interdependence and therefore any event that occurs within an ecosystem affects all parts. The influence that the environment has on subjects that maydevelop an illness has been amply recognized. For some autoimmune diseases such as systemic lupus erythematosus (SLE), the possibility of its development under ultraviolet light and prolonged exposure to sunlight has been recognized. Microorganisms may activate other illnesses such as reactive arthritis. Substances such as alfalfa are also able to unleash disease activity. Laboratory workers who manipulate sera of patients with autoimmune rheumatic disorders develop antibodies to the sera that they are working with. It is thus that environmental sciences and focused research allow the development of a new approach to the study of possible pathogenic mechanisms in the appearance of certain rheumatic disorders. This article reviews the main existing evidence and proposes certain hypotheses derived from it.