Lactobacillus rhamnosus protects human colonic muscle from pathogen lipopolysaccharide-induced damage

BACKGROUND

Lactobacillus species might positively affect gastrointestinal motility. These Gram-positive bacteria bind Toll-like receptor 2 (TLR2) that elicits anti-inflammatory activity and exerts protective effects on damage induced by lipopolysaccharide (LPS). Whether such effect occurs in gastrointestinal smooth muscle has not been established yet. Aim of this study was to characterize the effects of Lactobacillus rhamnosus GG (LGG) and of supernatants harvested from LGG cultures on human colonic smooth muscle and to explore their protective activity against LPS-induced myogenic morpho-functional alterations.

METHODS

The effects of LGG (ATCC 53103 strain) and of supernatants have been tested on both human colonic smooth muscle strips and isolated cells in the absence or presence of LPS obtained from a pathogenic strain of Escherichia coli. Their effects on myogenic morpho-functional properties, on LPS-induced NFκB activation, and on cytokine production have been evaluated. Toll-like receptor 2 expression has been analyzed by qPCR and flow cytometry.

KEY RESULTS

Lactobacillus rhamnosus GG exerted negligible transient effects per se whereas it was capable of activating an intrinsic myogenic response counteracting LPS-induced alterations. In particular, both LGG and supernatants significantly reduced the LPS-induced morpho-functional alterations of muscle cells, i.e. cell shortening and inhibition of contractile response. They also hindered LPS-induced pro-inflammatory effects by decreasing pro-inflammatory transcription factor NFκB activation and pro-inflammatory cytokine IL-6 secretion, and restored the secretion levels of anti-inflammatory cytokine IL10.

CONCLUSIONS & INFERENCES

Taken together these data demonstrate that LGG protects human colonic smooth muscle from LPS-induced myogenic damage and might be beneficial on intestinal motor disorders due to bacterial infection.

Constitutive localization of DR4 in lipid rafts is mandatory for TRAIL-induced apoptosis in B-cell hematologic malignancies

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) acts as an apoptosis inducer for cancer cells sparing non-tumor cell targets. However, several phase I/II clinical trials have shown limited benefits of this molecule. In the present work, we investigated whether cell susceptibility to TRAIL ligation could be due to the presence of TRAIL death receptors (DRs) 4 and 5 in membrane microdomains called lipid rafts. We performed a series of analyses, either by biochemical methods or fluorescence resonance energy transfer (FRET) technique, on normal cells (i.e. lymphocytes, fibroblasts, endothelial cells), on a panel of human cancer B-cell lines as well as on CD19⁺ lymphocytes from patients with B-chronic lymphocytic leukemia, treated with different TRAIL ligands, that is, recombinant soluble TRAIL, specific agonistic antibodies to DR4 and DR5, or CD34⁺ TRAIL-armed cells. Irrespective to the expression levels of DRs, a molecular interaction between ganglioside GM3, abundant in lymphoid cells, and DR4 was detected. This association was negligible in all non-transformed cells and was strictly related to TRAIL susceptibility of cancer cells. Interestingly, lipid raft disruptor methyl-beta-cyclodextrin abrogated this susceptibility, whereas the chemotherapic drug perifosine, which induced the recruitment of TRAIL into lipid microdomains, improved TRAIL-induced apoptosis. Accordingly, in ex vivo samples from patients with B-chronic lymphocytic leukemia, the constitutive embedding of DR4 in lipid microdomains was associated per se with cell death susceptibility, whereas its exclusion was associated with TRAIL resistance. These results provide a key mechanism for TRAIL sensitivity in B-cell malignances: the association, within lipid microdomains, of DR4 but not DR5, with a specific ganglioside, that is the monosialoganglioside GM3. On these bases we suggest that lipid microdomains could exert a catalytic role for DR4-mediated cell death and that an ex vivo quantitative FRET analysis could be predictive of cancer cell sensitivity to TRAIL.

[Comparison of acceptance tests of 5 linear electron accelerators for radiotherapy]

The acceptance tests of five electron linear accelerators have been analyzed to compare their completeness, the standards specified by the manufacturers and the measured deviations. Involved tests were relative to geometrical and mechanical parameters, photon and electron beam characteristics, dose monitoring systems, treatment table and safety systems. The comparison of acceptance tests has shown a significant nonuniformity, also due to the absence of a specific legislation; anyway, the measured deviations generally appeared to be within internationally recommended values.