Bifidobacterium Infantis 35624 Protects Against Salmonella-Induced Reductions in Digestive Enzyme Activity in Mice by Attenuation of the Host Inflammatory Response

OBJECTIVES: Salmonella-induced damage to the small intestine may decrease the villi-associated enzyme activity, causing malabsorption of nutrients and diarrhea, and thus contribute to the symptoms of infection. The objective of this study was to determine the mechanism by which different doses and durations of Salmonella infection and lipopolysaccharide (LPS) affect brush border enzyme activity in the mouse, and to determine if the probiotic Bifidobacterium longum subspecies infantis 35624 could attenuate the intestinal damage. METHODS: BALB/c mice were challenged with Salmonella enterica serovar Typhimurium UK1 at various doses (10(2)-10(8) colony-forming unit (CFU)) and durations (10(6) CFU for 1-6 days). Mice were also treated with B. longum subsp. infantis 35624 for 2 weeks before and during a 6-day S. Typhimurium challenge (10(6) CFU), or before injection of LPS. The small intestine was assessed for morphological changes, mRNA expression of cytokines, and activity of the brush border enzymes sucrase-isomaltase, maltase, and alkaline phosphatase. RESULTS: S. Typhimurium infection significantly reduced the activity of all brush border enzymes in a dose- and time-dependent manner (P<0.05). This also occurred following injection of LPS. Pre-treatment with B. longum subsp. infantis 35624 prevented weight loss, protected brush border enzyme activity, reduced the small intestinal damage, and inhibited the increase in interleukin (IL)-10 and IL-8 expression due to Salmonella challenge. CONCLUSIONS: Salmonella infection reduces the small intestinal brush border enzyme activity in mice, with the level of reduction and associated weight loss increasing with dose and duration of infection. B. longum subsp. infantis 35624 treatment attenuated the effect of Salmonella infection on brush border enzyme activity and weight loss, which may be due to modulation of the host immune response

Life on Arginine for Mycoplasma hominis: Clues from Its Minimal Genome and Comparison with Other Human Urogenital Mycoplasmas

Mycoplasma hominis is an opportunistic human mycoplasma. Two other pathogenic human species, M. genitalium and Ureaplasma parvum, reside within the same natural niche as M. hominis: the urogenital tract. These three species have overlapping, but distinct, pathogenic roles. They have minimal genomes and, thus, reduced metabolic capabilities characterized by distinct energy-generating pathways. Analysis of the M. hominis PG21 genome sequence revealed that it is the second smallest genome among self-replicating free living organisms (665,445 bp, 537 coding sequences (CDSs)). Five clusters of genes were predicted to have undergone horizontal gene transfer (HGT) between M. hominis and the phylogenetically distant U. parvum species. We reconstructed M. hominis metabolic pathways from the predicted genes, with particular emphasis on energy-generating pathways. The Embden–Meyerhoff–Parnas pathway was incomplete, with a single enzyme absent. We identified the three proteins constituting the arginine dihydrolase pathway. This pathway was found essential to promote growth in vivo. The predicted presence of dimethylarginine dimethylaminohydrolase suggested that arginine catabolism is more complex than initially described. This enzyme may have been acquired by HGT from non-mollicute bacteria. Comparison of the three minimal mollicute genomes showed that 247 CDSs were common to all three genomes, whereas 220 CDSs were specific to M. hominis, 172 CDSs were specific to M. genitalium, and 280 CDSs were specific to U. parvum. Within these species-specific genes, two major sets of genes could be identified: one including genes involved in various energy-generating pathways, depending on the energy source used (glucose, urea, or arginine) and another involved in cytadherence and virulence. Therefore, a minimal mycoplasma cell, not including cytadherence and virulence-related genes, could be envisaged containing a core genome (247 genes), plus a set of genes required for providing energy. For M. hominis, this set would include 247+9 genes, resulting in a theoretical minimal genome of 256 genes

Effects of the TLR2 Agonists MALP-2 and Pam3Cys in Isolated Mouse Lungs

Background: Gram-positive and Gram-negative bacteria are main causes of pneumonia or acute lung injury. They are recognized by the innate immune system via toll-like receptor-2 (TLR2) or TLR4, respectively. Among all organs, the lungs have the highest expression of TLR2 receptors, but little is known about the pulmonary consequences of their activation. Here we studied the effects of the TLR2/6 agonist MALP-2, the TLR2/1 agonist Pam 3Cys and the TLR4 agonist lipopolysaccharide (LPS) on pro-inflammatory responses in isolated lungs. Methodology/Principal Findings: Isolated perfused mouse lungs were perfused for 60 min or 180 min with MALP-2 (25 ng/ mL), Pam3Cys (160 ng/mL) or LPS (1 mg/mL). We studied mediator release by enzyme linked immunosorbent assay (ELISA), the activation of mitogen activated protein kinase (MAPK) and AKT/protein kinase B by immunoblotting, and gene induction by quantitative polymerase chain reaction. All agonists activated the MAPK ERK1/2 and p38, but neither JNK or AKT kinase. The TLR ligands upregulated the inflammation related genes Tnf, Il1b, Il6, Il10, Il12, Ifng, Cxcl2 (MIP-2a) and Ptgs2. MALP-2 was more potent than Pam 3Cys in inducing Slpi, Cxcl10 (IP10) and Parg. Remarkable was the strong induction of Tnc by MALP2, which was not seen with Pam 3Cys or LPS. The growth factor related genes Areg and Hbegf were not affected. In addition, all three TLR agonists stimulated the release of IL-6, TNF, CXCL2 and CXCL10 protein from the lungs

Release of Toll-Like Receptor-2-Activating Bacterial Lipoproteins in Shigella flexneri Culture Supernatants

Shigella spp. cause dysentery, a severe form of bloody diarrhea. Apoptosis, or programmed cell death, is induced during Shigella infections and has been proposed to be a key event in the pathogenesis of dysentery. Here, we describe a novel cytotoxic activity in the sterile-culture supernatants of Shigella flexneri. An identical activity was identified in purified S. flexneri endotoxin, defined here as a mixture of lipopolysaccharide (LPS) and endotoxin-associated proteins (EP). Separation of endotoxin into EP and LPS revealed the activity to partition exclusively to the EP fraction. Biochemical characterization of S. flexneri EP and culture supernatants, including enzymatic deactivation, reverse-phase high-pressure liquid chromatography analysis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and a Toll-like receptor-2 (TLR2) activation assay, indicates that the cytotoxic component is a mixture of bacterial lipoproteins (BLP). We show that biologically active BLP are liberated into culture supernatants of actively growing S. flexneri. In addition, our data indicate that BLP, and not LPS, are the component of endotoxin of gram-negative organisms responsible for activating TLR2. The activation of apoptosis by BLP shed from S. flexneri is discussed as a novel aspect of the interaction of bacteria with the host