Diosmectite treatment reduces stress-induced visceral hypersensitivity but does not affect the gut microbiota in rats.

OBJECTIVE: To evaluate the effect of diosmectite on visceral hypersensitivity and intestinal transit in a rat chronic stress model and on the faecal microbiota. MATERIALS AND METHODS: Wistar rats (175-225 g; n=10) were randomized into four groups: diosmectite/control, diosmectite/stress, vehicle/control, and vehicle/stress. Diosmectite (500 mg/kg, PO) was administered for five days for assessment of visceral hypersensitivity and intestinal transit and for three weeks for assessment of faecal microbiota. The stress procedure was a daily chronic passive water avoidance session. Intestinal transit was evaluated by faecal output in the hour following the last stress session. Visceral sensitivity in response to colorectal distension (CRD) was assessed at baseline and 30 min after the last stress session. In another group of rats, faecal material was collected before and after treatment with diosmectite or vehicle; genomic DNA was extracted and sequenced to characterize the faecal microbiota. RESULTS: Under nonstressed conditions, diosmectite treatment did not modify intestinal transit compared to the vehicle group (p=0.33). After the stress procedure, a trend towards reduction in stress-induced stool production was observed with diosmectite compared to vehicle (6.3±1.1 vs. 4.9±1.2 respectively; p=0.38). In the control condition, the number of CRD-evoked abdominal contractions was 20±4 after diosmectite and 24±2 after vehicle (p=0.75). In the stressed condition, the number of contractions increased to 34.4±2.4 after vehicle (p<0.05 compared to control). Stress-related hypersensitivity was attenuated after diosmectite treatment (26.9±2.2; p<0.05 compared to vehicle). No relevant changes were observed in the faecal microbiotic profile after treatment with diosmectite or vehicle. CONCLUSIONS: Diosmectite treatment attenuates stress-induced visceral hypersensitivity; this effect may contribute to the therapeutic effect of diosmectite in IBS in humans.

Increased fermentable carbohydrate intake alters colonic mucus barrier function through glycation processes and increased mast cell counts.

Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder for which dietary interventions can be a useful treatment. In recent years, the low-FODMAP approach is gaining traction in this regard. The fermentation of these non-absorbed carbohydrates by the gut microbiota can generate toxic glycating metabolites, such as methylglyoxal. These metabolites can have harmful effects by their role in the generation of advanced glycation end products (AGEs), which activates Receptor for AGEs (AGER). Mast cells can be stimulated by AGEs and play a role in IBS. We have treated mice with lactose or fructo-oligosaccharides (FOS), with or without co-administration of pyridoxamine and investigated the colonic mucus barrier. We have found that an increased intake of lactose and fructo-oligosaccharides induces a dysregulation of the colonic mucus barrier, increasing mucus discharge in empty colon, while increasing variability and decreasing average thickness mucus layer covering the fecal pellet. Changes were correlated with increased mast cell counts, pointing to a role for the crosstalk between these and goblet cells. Additionally, AGE levels in colonic epithelium were increased by treatment with the selected fermentable carbohydrates. Observed effects were prevented by co-treatment with anti-glycation agent pyridoxamine, implicating glycation processes in the negative impact of fermentable carbohydrate ingestion. This study shows that excessive intake of fermentable carbohydrates can cause colonic mucus barrier dysregulation in mice, by a process that involves glycating agents and increased mucosal mast cell counts.

Early life stress in mice is a suitable model for Irritable Bowel Syndrome but does not predispose to colitis nor increase susceptibility to enteric infections.

Neonatal period is characterized by an immature intestinal barrier. Scattered evidence suggests that early life stressful events induce long lasting alterations of intestinal homeostasis mimicking Irritable Bowel Syndrome (IBS). Those observations highlighting defect of intestinal barrier by early life stress questioned its potential role as a risk factor for gastrointestinal disorders such as colitis and infections. In this study, we aimed to analyze if maternal separation (MS) in mice mimicks IBS main features. We next addressed whether MS could trigger or exacerbate colitis in genetically predisposed mice and/or enhance susceptibility to gastrointestinal infections in wild type mice. MS induced main features of IBS in adult wild type male mice i.e. intestinal hyperpermeability, visceral hypersensitivity, microbiota dysbiosis, bile acid malabsorption and low grade inflammation in intestine associated with a defect of Paneth cells and the ILC3 population. This breach in mucosal barrier functions in adults was associated with a systemic IgG response against commensal E. coli and increased IFNγ secretion by splenocytes. However, in IL10-/- mice, MS did not trigger nor worsen colitis. Furthermore, wild type mice submitted to MS did not show increase susceptibility to gastrointestinal infections (S. Typhimurium, L. monocytogenes or T. gondii) compared to controls. Altogether, our results identify MS in mice as a good experimental model for IBS mimicking all the main features. In addition, early life stress, even though it has long lasting consequences on intestinal homeostasis, does not constitute a facilitating factor to colitis in predisposed individuals nor to gastrointestinal infections in wild type mice.

Mucus organisation is shaped by colonic content; a new view.

The colonic mucus barrier is commonly described as a continuous double layer covering the epithelium, separating the microbiota from the intestinal tissue. This model is currently considered valid throughout the colon. The colon is characterised by regional anatomo-functional specificities such as presence and consistency of contents and location. In this study, we characterised the organisation of the colonic mucus barrier in proximal and distal colon of rodents by histological and FISH staining, taking into account aforementioned specificities. By using longitudinal sections and imaging extensive areas of tissue with and without colonic contents, we have obtained a spatiotemporal overview of mucus organisation in the colon. We describe for the first time that the colonic mucus layer covers the faeces instead of the epithelium in the distal colon. This faecal mucus layer confines the microbiota to the faeces and prevents it from remaining in empty distal colon. In the proximal colon, the mucus did not form a separating layer between bacteria and epithelium. We conclude that the organisation of colonic mucus is reliant on the presence of the colonic content, and the location within the colon. Our findings reopen the discussion on the nature of the colonic mucus barrier.

Luminal contents from the gut of colicky infants induce visceral hypersensitivity in mice.

BACKGROUND: The pathophysiology of infantile colic is poorly understood, though various studies report gut microbiota dysbiosis in colicky infants. We aimed to test the hypothesis that colic-related dysbiosis is associated with visceral hypersensitivity triggered by an altered luminal milieu. METHODS: Fecal samples from seven colicky and seven non-colicky infants were studied. Fecal supernatants (FS) were infused into the colons of C57/Bl6 mice (n=10/specimen). Visceral sensitivity was subsequently assessed in the animals by recording their abdominal muscle response to colorectal distension (CRD) by electromyography (EMG). Serine and cysteine protease activities were assessed in FS with specific substrates. Infant fecal microbiota composition was analyzed by DNA extraction and 16S rRNA gene pyrosequencing. KEY RESULTS: FS from colicky infants triggered higher EMG activity than FS from non-colicky infants in response to both the largest CRD volumes and overall, as assessed by the area under the curve of the EMG across all CRD volumes. Infant crying time strongly correlated with mouse EMG activity. Microbiota richness and phylogenetic diversity were increased in the colicky group, without showing prominent microbial composition alterations. Only Bacteroides vulgatus and Bilophila wadsworthia were increased in the colicky group. Bacteroides vulgatus abundance positively correlated with visceral sensitivity. No differences were found in protease activities. CONCLUSIONS & INFERENCES: Luminal contents from colicky infants trigger visceral hypersensitivity, which may explain the excessive crying behavior of these infants. Additional studies are required to determine the nature of the compounds involved, their mechanism of action, and the potential implications of intestinal microbiota in their generation.

Maternal high-fat diet prevents developmental programming by early-life stress.

Anxiety disorders and depression are well-documented in subjects exposed to adverse childhood events. Recently, maternal obesity and/or maternal consumption of high-fat diets (HFD) have been also proposed as risk factors for offspring mental health. Here using an animal model in rats, we explored the combinatorial effects of a maternal HFD (40% of energy from fat without impact on maternal weight; during gestation and lactation) and maternal separation (MS) in offspring. In the prefrontal cortex (PFC) of pups, MS led to changes in the expression of several genes such as Bdnf (brain derived neurotrophic factor), 5HT-r1a (serotonin receptor 1a) and Rest4 (neuron-restrictive silencer element, repressor element 1, silencing transcription factor (Rest), splicing variant 4). Surprisingly, perinatal HFD strongly attenuated the developmental alterations induced by MS. Furthermore, maternal HFD totally prevented the endophenotypes (anxiety, spatial memory, social behavior, hypothalamic-pituitary-adrenal (HPA) axis response to stress, hippocampal neurogenesis and visceral pain) associated with MS at adulthood. Finally, we also demonstrated that HFD intake reduced anxiety and enhanced maternal care in stressed dams. Overall, our data suggest that a HFD restricted to gestation and lactation, which did not lead to overweight in dams, had limited effects in unstressed offspring, highlighting the role of maternal obesity, rather than fat exposure per se, on brain vulnerability during development.

Improving outcomes of severe infections by multidrug-resistant pathogens with polyclonal IgM-enriched immunoglobulins.

The emergence of infections by multidrug-resistant (MDR) Gram-negative bacteria, which is accompanied by considerable mortality due to inappropriate therapy, led to the investigation of whether adjunctive treatment with one polyclonal IgM-enriched immunoglobulin preparation (IgGAM) would improve outcomes. One hundred patients in Greece with microbiologically confirmed severe infections by MDR Gram-negative bacteria acquired after admission to the Intensive Care Unit and treated with IgGAM were retrospectively analysed from a large prospective multicentre cohort. A similar number of patient comparators well-matched for stage of sepsis, source of infection, appropriateness of antimicrobials and co-morbidities coming from the same cohort were selected. All-cause 28-day mortality was the primary end point; mortality by extensively drug-resistant (XDR) pathogens and time to breakthrough bacteraemia were the secondary end points. Fifty-eight of the comparators and 39 of the IgGAM-treated cases died by day 28 (p 0.011). The OR for death under IgGAM treatment was 0.46 (95% CI 0.26-0.85). Stepwise regression analysis revealed that IgGAM was associated with favourable outcome whereas acute coagulopathy, cardiovascular failure, chronic obstructive pulmonary disease and chronic renal disease were associated with unfavourable outcome. Thirty-nine of 62 comparators (62.9%) were infected by XDR Gram-negative bacteria and died by day 28 compared with 25 of 65 cases treated with IgGAM (38.5%) (p 0.008). Median times to breakthrough bacteraemia were 4 days and 10 days, respectively (p <0.0001). Results favour the use of IgGAM as an adjunct to antimicrobial treatment for the management of septic shock caused by MDR Gram-negative bacteria. A prospective randomized trial is warranted.

Anti-nociceptive effect of Faecalibacterium prausnitzii in non-inflammatory IBS-like models.

Visceral pain and intestinal dysbiosis are associated with Irritable Bowel Syndrome (IBS), a common functional gastrointestinal disorder without available efficient therapies. In this study, a decrease of Faecalibacterium prausnitzii presence has been observed in an IBS-like rodent model induced by a neonatal maternal separation (NMS) stress. Moreover, it was investigated whether F. prausnitzii may have an impact on colonic sensitivity. The A2-165 reference strain, but not its supernatant, significantly decreased colonic hypersensitivity induced by either NMS in mice or partial restraint stress in rats. This effect was associated with a reinforcement of intestinal epithelial barrier. Thus, F. prausnitzii exhibits anti-nociceptive properties, indicating its potential to treat abdominal pain in IBS patients.

Alpha1-microglobulin as an early biomarker of sepsis-associated acute kidney injury: a prospective cohort study.

BACKGROUND: Sepsis emerges as the leading risk factor for acute kidney injury (AKI) development in critically ill patients. Much effort has been invested so far on early diagnosis of AKI using promising biomarkers. This study aimed to determine whether urine alpha1-microglobulin (α1m), a lipocaline member previously used as an indicator of proximal tubular dysfunction, can early predict the development of sepsis-associated AKI (SAAKI) in critically ill patients. METHODS: A prospective, observational study was conducted in a single center Intensive Care Unit (ICU). Patients with normal renal function admitted to the ICU followed for sepsis and AKI development. Urine α1m levels were analyzed in pooled samples from 24-hour urine collections on sepsis onset and at various time points thereafter. The diagnostic performance of urine α1m was assessed using thenonparametriccalculation of the area under the curve (AUC) of the receiver operating characteristic (ROC) curve. RESULTS: Among 286 critically ill patients admitted to our ICU in a year, 45 patients with sepsis met the inclusion criteria. SAAKI developed in 16 septic patients (35.6%). Urine α1m levels were significantly elevated in all septic patients (average value of all samples on the day of sepsis: 46.02 ± 7.17 mg/l) and showed a trend to increase in patients who finally developed SAAKI. The AUC for SAAKI prediction according to α1m urine levels 24-hours before SAAKI onset was 0.739 (sensitivity 87.5%, specificity 62.07%, cutoff level 47.9 mg/l). Urine α1m 24-hours before SAAKI, serum creatinine on sepsis onset and Acute Physiology and Chronic Health Evaluation II (APACHE II) score on sepsis onset emerged as the most powerful independent predictors of SAAKI. The combination of these three parameters improved the AUC for SAAKI prediction to 0.944. CONCLUSION: Urine α1m levels might help in the early prediction of SAAKI development and may prove useful biomarker. The pathogenetic implications of α1m in sepsis and SAAKI need further investigation. Hippokratia 2014; 18 (3): 262-268.

Probiotic gut effect prevents the chronic psychological stress-induced brain activity abnormality in mice.

BACKGROUND: A probiotic formulation (Lactobacillus helveticus R0052 and Bifidobacterium longum R0175 combination, Probio'Stick(®) ) displays anxiolytic-like activity and reduces apoptosis in the lymbic system in animal models of depression. Based on the hypothesis that modulation of gut microbiota by this probiotic formulation has beneficial effects on brain activity in stress conditions, we report a set of probiotic-evoked physiological, cellular, and molecular events in the brain of Probio'Stick(®) pretreated mice submitted to chronic psychological stress. METHODS: Water avoidance stress (WAS) was applied or not (sham). Hypothalamic-pituitary-adrenal (HPA) axis and autonomic nervous system (ANS) responses to the chronic stress were assessed through plasma corticosterone and catecholamine measurements. Specific markers for neuronal activity, neurogenesis, and synaptic plasticity were used to assess brain activity. In addition, gut permeability and tight junction (TJ) proteins levels were also determinated. KEY RESULTS: We observed that a pretreatment with the probiotic formulation attenuated HPA axis and ANS activities in response to WAS, and reduced cFos expression in different brain areas but Lactobacillus salivarius (a negative control) treatment was ineffective on these parameters. Moreover, probiotic pretreatment prevented the WAS-induced decrease hippocampal neurogenesis and expression changes in hypothalamic genes involved in synaptic plasticity. These central effects were associated with restoration of TJ barrier integrity in stressed mice. CONCLUSIONS & INFERENCES: These data suggest that chronic stress-induced abnormal brain plasticity and reduction in neurogenesis can be prevented by a pretreatment with the Probio'Stick(®) formulation, suggesting that probiotics modulate neuroregulatory factors and various signaling pathways in the central nervous system involved in stress response.

Susceptibility to stress-induced visceral sensitivity: a bad legacy for next generations.

Despite high prevalence, the precise irritable bowel syndrome (IBS) pathophysiology remains poorly understood likely due to the heterogeneity of IBS populations and the multifactorial etiology of this disorder. Among risk factors, genetic predisposition and early life trauma have been reported. In this context, the debate on genetic or environmental influences in the IBS pathogenesis is still open. The study by van der Wijngaard et al., reporting for the first time that susceptibility to stress-induced visceral hypersensitivity in maternally separated rats can be transferred to the next generation without any further exposure of F2 individuals to maternal separation, supports the importance of environmental influence in the IBS phenotype. Epigenetic mechanisms such as hypermethylation in the promoter region of the glucocorticoid receptor gene mediating the long-term and transgenerational behavioral effects of maternal care on the development have been shown in some but not in all studies. Van der Wijngaard et al. incriminated maternal care in the transmitted susceptibility to stress-induced visceral hypersensitivity, but not changes in glucocorticoid receptor protein expression in the brain. This finding opens a broad field of future directions aimed at evaluating the mechanisms involved in the transmission across generations of the digestive features of IBS, including, for example, on the role of gut microbiota changes in vertical transmission or epigenetic modifications of intestinal mast cells and the junctional region of intestinal epithelial cells in vertical transfer.

A marketed fermented dairy product containing Bifidobacterium lactis CNCM I-2494 suppresses gut hypersensitivity and colonic barrier disruption induced by acute stress in rats.

BACKGROUND: Fermented milk (FM) containing Bifidobacterium lactis CNCM I-2494 and yogurt strains improves irritable bowel syndrome (IBS) symptoms in constipated IBS patients. In rats, stressful events exacerbate IBS symptoms and result in the alteration of gut sensitivity and permeability via epithelial cell cytoskeleton contraction. In a stress model, we aimed at evaluating the effect of B. lactis CNCM I-2494 as a pure strain or contained in an FM product on visceral sensitivity and the impact of this FM on intestinal barrier integrity. METHODS: Visceral sensitivity was analyzed in rats subjected to partial restraint stress (PRS). Rats received during 15 days the B. lactis as a pure strain (10(6) to 10(10) CFU mL(-1)), B. lactis in an FM product (10(8) CFU g(-1), diluted or not), or a control product. Gut paracellular permeability, colonic occluding and Jam-A proteins, and blood endotoxin levels were determined in rats receiving B. lactis in an FM product submitted or not to a PRS. KEY RESULTS: The FM product showed a dose-dependent inhibitory effect on stress-induced visceral hypersensitivity. A similar antihyperalgesic effect was observed at 10(10) CFU mL(-1) of pure B. lactis administration. The FM product prevented the increase in intestinal permeability induced by PRS and restored occludin and JAM-A expressions to control levels. The FM product abolished the increase concentration of blood endotoxin induced by PRS. CONCLUSIONS & INFERENCES: This study illustrates that a probiotic food containing B. lactis CNCM I-2494 strain reduces visceral hypersensitivity associated with acute stress by normalizing intestinal epithelial barrier via a synergistic interplay with the different probiotic strains and/or metabolites contained in this product.

Combination of allergic factors can worsen diarrheic irritable bowel syndrome: role of barrier defects and mast cells.

OBJECTIVES: Recent evidence suggests a role for increased colonic permeability and mucosal mast cell (MC) mediators on symptoms related to the irritable bowel syndrome (IBS). Whether allergic factors (AFs) are involved in the pathophysiology of IBS is unclear. We addressed the question of the possible influence of an allergic background on IBS symptoms. METHODS: We assessed paracellular permeability, mucosal MCs counts, and spontaneous release of tryptase of colonic biopsy specimens in 34 IBS patients and 15 healthy subjects. The severity of IBS was assessed through self-reported questionnaires. All individuals were tested for the presence of AF, including self-perception of adverse reaction to food, personal and familial history of atopic disease, elevated total or specific immunoglobulin E against food/inhalant antigens, blood eosinophilia, and skin tests. RESULTS: IBS patients had significant enhanced colonic permeability, higher number of MCs, and spontaneous release of tryptase than healthy subjects. The severity of IBS was significantly correlated with colonic permeability (r=0.48, P=0.004), MCs counts (r=0.36, P=0.03), and tryptase (r=0.48, P=0.01). In 13 IBS patients (38.2%) having at least three AFs, symptoms scores, colonic permeability, MCs counts, and tryptase release by colonic biopsies were significantly higher than in those with less than three AFs. IBS patients with at least three AFs were more prone to diarrhea or alternating symptoms. None AF was found to be predictive of IBS severity. CONCLUSIONS: In IBS patients, the presence of an allergic background correlates with a more severe disease and diarrhea predominance, possibly by enhancing mucosal MC activation and paracellular permeability.

Proteinase-activated receptor-4 evoked colorectal analgesia in mice: an endogenously activated feed-back loop in visceral inflammatory pain.

BACKGROUND: Activation of proteinase-activated receptor-4 (PAR-4) from the colonic lumen has an antinociceptive effect to colorectal distension (CRD) in mice in basal conditions. We aimed to determine the functional localization of the responsible receptors and to test their role in two different hyperalgesia models. METHODS: Mice received PAR-4 activating peptide (PAR-4-AP, AYPGKF-NH(2)) or vehicle intraperitoneally (IP), and abdominal EMG response to CRD was measured. The next group received PAR-4-AP intracolonically (IC) with or without 2,4,6-triaminopyrimidine, a chemical tight junction blocker, before CRD. The SCID mice were used to test the role of lymphocytes in the antihyperalgesic effect. The effects of PAR-4-AP and PAR-4-antagonist (P4pal-10) were evaluated in water avoidance stress (WAS) model and low grade 2,4,6-trinitrobenzene sulfonic acid (TNBS) colitis. Spinal Fos protein expression was visualized by immunohistochemistry. KEY RESULTS: The antinociceptive effect of PAR-4-AP disappeared when was administrered IP, or with the blockade of colonic epithelial tight junctions, suggesting that PAR-4-AP needs to reach directly the nerve terminals in the colon. The CRD-induced spinal Fos overexpression was reduced by 43% by PAR-4-AP. The PAR-4-AP was antihyperalgesic in both hyperalgesia models and in mice with impaired lymphocytes. The PAR-4-antagonist significantly increased the TNBS, but not the WAS-induced colonic hyperalgesia. CONCLUSIONS & INFERENCES: The antinociceptive effect of PAR-4-AP depends on its penetration to the colonic mucosa. The PAR-4 activation is endogenously involved as a feedback loop to attenuate inflammatory colonic hyperalgesia to CRD.

Guanylate cyclase C-mediated antinociceptive effects of linaclotide in rodent models of visceral pain.

BACKGROUND Linaclotide is a novel, orally administered investigational drug currently in clinical development for the treatment of constipation-predominant irritable bowel syndrome (IBS-C) and chronic idiopathic constipation. Visceral hyperalgesia is a major pathophysiological mechanism in IBS-C. Therefore, we investigated the anti-nociceptive properties of linaclotide in rodent models of inflammatory and non-inflammatory visceral pain and determined whether these pharmacological effects are linked to the activation of guanylate cyclase C (GC-C). METHODS Orally administered linaclotide was evaluated in non-inflammatory acute partial restraint stress (PRS) and acute water avoidance stress (WAS) models in Wistar rats, and in a trinitrobenzene sulfonic acid (TNBS)-induced inflammatory model in Wistar rats and GC-C null mice. KEY RESULTS In TNBS-induced colonic allodynia, linaclotide significantly decreased the number of abdominal contractions in response to colorectal distension without affecting the colonic wall elasticity change in response to distending pressures after TNBS. However, linaclotide had no effect on visceral sensitivity under basal conditions. In addition, linaclotide significantly decreased colonic hypersensitivity in the PRS and WAS models. In wild type (wt) and GC-C null mice, the instillation of TNBS induced similar hyperalgesia and allodynia. However, in post-inflammatory conditions linaclotide significantly reduced hypersensitivity only in wt mice, but not in GC-C null mice. CONCLUSIONS & INFERENCES These findings indicate that linaclotide has potent anti-nociceptive effects in several mechanistically different rodent models of visceral hypersensitivity and that these pharmacological properties of linaclotide are exerted through the activation of the GC-C receptor. Therefore, linaclotide may be capable of decreasing abdominal pain in patients suffering from IBS-C.

Lactobacillus farciminis treatment attenuates stress-induced overexpression of Fos protein in spinal and supraspinal sites after colorectal distension in rats.

Abstract Irritable bowel syndrome (IBS), frequently associated with psychological distress, is characterized by hypersensitivity to gut wall distension. Some probiotics are able to alleviate IBS symptoms and reduce visceromotor response to mechanical stimuli in animals. Moreover, we have previously shown that Lactobacillus farciminis treatment abolished the hyperalgesia to colorectal distension (CRD) induced by acute stress. The aims of the present study were to determine whether (i) stress-induced visceral hyperalgesia modifies the expression of Fos, a marker of general neuronal activation, induced by CRD, (ii) this activation can be modulated by L. farciminis treatment. Female rats were treated by L. farciminis and CRD was performed after partial restraint stress (PRS) or sham-PRS. The expression of Fos protein was measured by immunohistochemistry. After CRD or PRS, Fos expression was increased in spinal cord section (S1), nucleus tractus solitarius (NTS), paraventricular nucleus (PVN) of the hypothalamus, and in the medial nucleus of the amygdala (MeA). The combination of both stimuli, PRS and CRD, markedly increased this Fos overexpression in the sacral spinal cord section, PVN and MeA, but not in NTS. By contrast, a pretreatment with L. farciminis significantly reduced the number of Fos positive cells in these area. This study shows that PRS enhances Fos protein expression induced by CRD at the spinal and supraspinal levels in rats. Lactobacillus farciminis treatment inhibited this enhancing effect, suggesting that the antinociceptive effect of this probiotic strain results from a decrease of the stress-induced activation/sensitization of sensory neurons at the spinal and supraspinal level.

The propofol infusion 'syndrome' in intensive care unit: from pathophysiology to prophylaxis and treatment.

Propofol is a short-acting intravenous anesthetic agent widely used for sedation in anesthesia and intensive care. However, during the last 15 years there have been quite a lot of publications reporting unexplained deaths among pediatric and adult critically ill patients. These cases shared common symptoms and signs unrelated with initial admission diagnosis and were under long-term propofol infusion at high doses. A new syndrome called 'propofol infusion syndrome' was defined, including cardiovascular instability, metabolic acidosis, hyperkalaemia and rhabdomyolysis, with no evidence for other known causes of myocardial failure. One common denominator in these patients was the presence of hypoxia and tissue hypoperfusion. It seems that during states of increased metabolic demand, the reduced energy production related to an inhibitory propofol action at the level of mitochondrial oxidative phosphorylation and lipid metabolism may lead to the manifestation of the syndrome. Furthermore, cases of early toxicity due to failure in cellular energy production with development of lactic acidosis have been also described during anesthesia. For the above reasons, recommendations for the limitation of propofol use have been devised by various institutions, whereas physicians need to be cautious when using prolonged propofol sedation and alert for early signs of toxicity.

Lactobacillus farciminis treatment suppresses stress induced visceral hypersensitivity: a possible action through interaction with epithelial cell cytoskeleton contraction.

BACKGROUND: Stress induced increase in colonic paracellular permeability results from epithelial cell cytoskeleton contraction and is responsible for stress induced hypersensitivity to colorectal distension (CRD). The probiotic Lactobacillus farciminis releases spontaneously nitric oxide (NO) in the colonic lumen in vivo and exerts anti-inflammatory effects. This study aimed: (i) to evaluate the effects of L farciminis on stress induced hypersensitivity to CRD and increase in colonic paracellular permeability; and (ii) to ascertain whether these effects are NO mediated and related to changes in colonocyte myosin light chain phosphorylation (p-MLC). METHODS: Female Wistar rats received either 10(11) CFU/day of L farciminis or saline orally over 15 days before partial restraint stress (PRS) or sham-PRS application. Visceral sensitivity to CRD and colonic paracellular permeability was assessed after PRS or sham-PRS. Haemoglobin was used as an NO scavenger. Western blotting for MLC kinase, MLC, and p-MLC were performed in colonic mucosa from L farciminis treated and control rats after PRS or sham-PRS. RESULTS: PRS significantly increased the number of spike bursts for CRD pressures of 30-60 mm Hg as well as colonic paracellular permeability. L farciminis treatment prevented both effects, while haemoglobin reversed the protective effects of L farciminis. p-MLC expression increased significantly from 15 to 45 minutes after PRS, and L farciminis treatment prevented this increase. CONCLUSION: L farciminis treatment prevents stress induced hypersensitivity, increase in colonic paracellular permeability, and colonocyte MLC phosphorylation. This antinociceptive effect occurs via inhibition of contraction of colonic epithelial cell cytoskeleton and the subsequent tight junction opening, and may also involve direct or indirect effects of NO produced by this probiotic.

LPS-induced lung inflammation is linked to increased epithelial permeability: role of MLCK.

The respiratory system is directly exposed to low levels of lipopolysaccharide (LPS), present as a contaminant on airborne particles. In cystic fibrosis, the prevailing data identify structural changes of the airway epithelium, as well as tight junction dilatation. This study was aimed at determining the contribution of myosin light chain kinase to maintaining airway epithelium barrier integrity in the lung inflammatory response to LPS in rats. The effects of the selective myosin light chain kinase inhibitor, 5-iodonaphthalene-1-sulphonyl-homopiperazine (ML-7), were evaluated: 1) on pulmonary inflammation and airway epithelium barrier permeability alterations induced by intra-tracheal LPS from Pseudomonas aeruginosa; and 2) on levels of the phosphorylated form of the myosin light chain, which is increased in a human airway epithelial cell line (NCI-H292) and tracheal tissue after LPS exposure. The results show that LPS increased airway epithelium barrier paracellular permeability and lung inflammation, and that pre-treatment with ML-7 inhibited both effects. This effect of ML-7 was associated with the inhibition of phosphorylated myosin light chain in both NCI-H292 cells and tracheal tissue. The data, obtained using in vivo and in vitro approaches, demonstrate a key role for myosin light chain kinase in lung inflammation, and suggest that myosin light chain kinase could be a potential target for novel drugs intended for relief of lung injury.