Increased Serum Endotoxin Research Articles

Preclinical efficacy and safety of encapsulated proliferating human hepatocyte organoids in treating liver failure

Alginate-encapsulated hepatocyte transplantation is a promising strategy to treat liver failure. However, its clinical application was impeded by the lack of primary human hepatocytes and difficulty in controlling their quality. We previously reported proliferating human hepatocytes (ProliHHs). Here, quality-controlled ProliHHs were produced in mass and engineered as liver organoids to improve their maturity. Encapsulated ProliHHs liver organoids (eLO) were intraperitoneally transplanted to treat liver failure animals. Notably, eLO treatment increased the survival of mice with post-hepatectomy liver failure (PHLF) and ameliorated hyperammonemia and hypoglycemia by providing liver functions. Additionally, eLO treatment protected the gut from PHLF-augmented permeability and normalized the increased serum endotoxin and inflammatory response, which facilitated liver regeneration. The therapeutic effect of eLO was additionally proved in acetaminophen-induced liver failure. Furthermore, we performed assessments of toxicity and biodistribution, demonstrating that eLO had no adverse effects on animals and remained non-tumorigenic.

Chronic ethanol exposure induced anxiety-like behaviour by altering gut microbiota and GABA system.

Ethanol, also known as alcohol, is one of the most common drinks in the world. Chronic ethanol exposure has been reported to induce mental disorders. Ethanol also has a strong effect on the gut microbiota. The gut microbiota has been reported to affect the brain via multiple pathways, including changes in γ-aminobutyric acid (GABA) system, and cause a variety of mental disorders. The GABA system in the cortex is associated with anxiety. However, the role of gut microbiota played in ethanol exposure-induced changes in the GABA system and anxiety is still not clear. We established a 30-day ethanol exposure mouse model and investigated the effects of microbiota using the antibiotic minocycline. Minocycline alleviated ethanol-induced anxiety-like behaviour, dysbiosis of microbiota, intestinal barrier disruption, increased serum endotoxin and interleukin (IL)-6. Minocycline also attenuated ethanol-induced apoptosis and decreased expression of glutamate decarboxylases (GADs) and GABRA1 in the prefrontal cortex. Our results indicated that gut microbiota plays an important role in ethanol-induced anxiety-like behaviour by altering the function of GABA system. In addition, causal mediation analysis showed that endotoxin and IL-6 may mediate the connection between the gut microbiota and the expression of GABAA receptor in the prefrontal cortex.

Butyrate ameliorates alcoholic fatty liver disease via reducing endotoxemia and inhibiting liver gasdermin D-mediated pyroptosis.

BackgroundAlcoholic fatty liver disease (AFLD) is characterized by hepatic steatosis and carries an elevated risk of cirrhosis and hepatocellular carcinoma. However, the mechanism of AFLD has not been elucidated thoroughly, and there are still no efficient therapies in clinic. Notably, butyrate, one kind of short-chain fatty acids produced by gut microbiota, has been shown to improve methionine-choline-deficient diet-induced non-alcoholic steatohepatitis. And our previous study found that butyrate ameliorated endotoxemia in db/db mice. In this study, we aimed to explore the role of butyrate in the development of AFLD.MethodsC57BL/6 mice were treated with saline (normal control), alcohol with or without butyrate by gavage for 6 months. AFLD was evaluated by the levels of serum alcohol, aspartate aminotransferase (AST), alanine transaminase (ALT), triglyceride (TG) and intrahepatic TG. And the histology and inflammation in liver and colon were analyzed using hematoxylin-eosin (H&E) staining, immunohistochemistry and western blot. In addition, gut microbiota composition was analyzed using the V3–V4 regions of the bacterial 16S ribosomal RNA gene by sequence. Furthermore, we performed in vitro experiment to verify the role of butyrate in hepatocyte by western blot and transmission electron microscopy.ResultsWe found that butyrate ameliorated alcohol-induced hepatic steatosis and inflammation. Furthermore, chronic alcohol feeding induced dysbiosis and dysfunction of the gut microbiota, disrupted the intestinal barrier, and increased serum endotoxin levels. Meanwhile, butyrate improved the intestinal barrier disruption and endotoxemia induced by alcohol, but did not significantly alleviate the microbiome dysfunction. Mechanistically, butyrate ameliorated AFLD by inhibiting gasdermin D (GSDMD)-mediated pyroptosis.ConclusionsIn summary, we found butyrate ameliorated alcoholic fatty liver by down-regulating GSDMD-mediated pyroptosis. We speculate that butyrate improves AFLD mainly by maintaining intestinal barrier function and alleviating gut leakage. These findings suggest that butyrate may have the potential to serve as a novel treatment for AFLD.

Lactobacillus reuteri alleviates Glucocorticoid induced Avascular Necrosis of Femoral Head.

Glucocorticoids (GC) are well‐known anti‐inflammatory drugs that are widely used to manage many diseases including autoimmune diseases such as rheumatoid arthritis and inflammatory bowel disease. Chronic GC use can have significant side effects including 1) dysbiosis (an imbalance of gut microbiota composition), 2) increased intestinal permeability which is linked to increased serum endotoxin levels, 3) trabecular bone loss and 4) osteonecrosis (i.e., avascular necrosis of the femur head). Especially, patients with GC‐induced osteonecrosis of femur head suffer from pain and stiffness, resulting in long‐term disability. Our lab and others have shown that the gut (microbiome and barrier function) regulates bone density. Recently, we have also shown that the probiotic Lactobacillus reuteri 6475 (LR) prevented GC‐induced trabecular bone loss in male and female mice. Based on these findings, we examined if LR treatment can prevent GC‐induced osteonecrosis (GCON) of the femur head. Male C57BL/6J (16‐weeks‐old) mice were treated for 8‐weeks with GC (2.5 mg/kg/day, subcutaneously slow release pellet) and supplemented with or without 3.3×108 cfu/ml LR in their drinking water. Femur immunohistochemistry examining von Willebrand factor positive blood vessels revealed that GC‐induced avascularization of the femur head was prevented by LR supplementation. Specifically, compared to controls, GC treatment caused a 50% reduction in the number of blood vessels in the femur head – this was completely prevented by LR treatment. Similarly, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) analyses determined that LR treatment prevented GC‐induced apoptosis of trabecular osteoblast and osteocytes. In addition, LR treatment prevented GC‐induced marrow adiposity. Consistent with these findings, microcomputed tomography indicated that femoral head bone loss was also prevented by LR treatment. Gene expression analysis of the femur head identified that GC‐induction of tumor necrosis factor alpha and Bcl‐2‐associated x protein (pro‐apoptotic) was prevented by LR. Together, these data indicate that probiotic LR supplementation prevents the pathological bone effects of GCs (avascularization, cell apoptosis, adiposity, bone loss) and may be a straightforward cost‐effective way to mitigate avascular necrosis of femoral head.Support or Funding InformationThese studies were supported by funding from the National Institute of Health, grants RO1 DK101050, AT007695 and by Michigan State University Foundation.

Involvement of the Gut Microbiota and Barrier Function in Glucocorticoid-Induced Osteoporosis.

Glucocorticoids (GCs) are potent immune-modulating drugs with significant side effects, including glucocorticoid-induced osteoporosis (GIO). GCs directly induce osteoblast and osteocyte apoptosis but also alter intestinal microbiota composition. Although the gut microbiota is known to contribute to the regulation of bone density, its role in GIO has never been examined. To test this, male C57/Bl6J mice were treated for 8 weeks with GC (prednisolone, GC-Tx) in the presence or absence of broad-spectrum antibiotic treatment (ABX) to deplete the microbiota. Long-term ABX prevented GC-Tx-induced trabecular bone loss, showing the requirement of gut microbiota for GIO. Treatment of GC-Tx mice with a probiotic (Lactobacillus reuteri [LR]) prevented trabecular bone loss. Microbiota analyses indicated that GC-Tx changed the abundance of Verrucomicobiales and Bacteriodales phyla and random forest analyses indicated significant differences in abundance of Porphyromonadaceae and Clostridiales operational taxonomic units (OTUs) between groups. Furthermore, transplantation of GC-Tx mouse fecal material into recipient naïve, untreated WT mice caused bone loss, supporting a functional role for microbiota in GIO. We also report that GC caused intestinal barrier breaks, as evidenced by increased serum endotoxin level (2.4-fold), that were prevented by LR and ABX treatments. Enhancement of barrier function with a mucus supplement prevented both GC-Tx-induced barrier leakage and trabecular GIO. In bone, treatment with ABX, LR or a mucus supplement reduced GC-Tx-induced osteoblast and osteocyte apoptosis. GC-Tx suppression of Wnt10b in bone was restored by the LR and high-molecular-weight polymer (MDY) treatments as well as microbiota depletion. Finally, we identified that bone-specific Wnt10b overexpression prevented GIO. Taken together, our data highlight the previously unappreciated involvement of the gut microbiota and intestinal barrier function in trabecular GIO pathogenesis (including Wnt10b suppression and osteoblast and osteocyte apoptosis) and identify the gut as a novel therapeutic target for preventing GIO. © 2019 American Society for Bone and Mineral Research.

Diurnal heat stress reduces pig intestinal integrity and increases endotoxin translocation.

Heat stress negatively affects performance and intestinal integrity of pigs. The objective of this study was to characterize the effects of diurnal heat stress (dHS) on nursery-grower pig performance, intestinal integrity, and lipopolysaccharide (LPS) translocation. Forty-eight nursery-grower gilts, individually penned, were randomly assigned to two treatments. Twenty-four pigs were then exposed to dHS for 3 d, 6 h at 38°C and 18 h at 32°C, at 40–60% humidity. The remaining pigs were maintained under thermal neutral (TN) conditions. Changes in pig rectal temperatures (Tr), respiration rates (RR), performance, and blood parameters were evaluated. Additionally, ex vivo ileum integrity was assessed with the Ussing chamber by measuring transepithelial resistance (TER), and 4 kDa fluorescein isothiocyanate (FITC)–dextran (FD4) and FITC–LPS mucosal to serosal flux. As expected, dHS increased pig Tr and RR (P < 0.05) and reduced pig performance (P < 0.05) on the 3-d period. Compared with TN, ileum TER (P = 0.04), FITC–LPS (P < 0.001), and FD4 (P = 0.011) permeability were significantly increased due to dHS. Compared with TN pigs, dHS increased serum endotoxin by 150% (P = 0.031). Altogether, 3-d dHS significantly reduced pig performance and intestinal integrity and increased blood endotoxin concentrations.

Bacillus subtilis and yeast cell wall improve the intestinal health of broilers challenged by Clostridium perfringens

ABSTRACT1. The objective was to investigate the effects of Bacillus subtilis, yeast cell wall (YCW) and their combination on intestinal health of broilers challenged by Clostridium perfringens over a 21-d period.2. Using a 5 × 2 factorial arrangement of treatments, 800 1-d-old male Cobb 500 broilers were used to study the effects of feed additives (without additive or with zinc bacitracin, B. subtilis, YCW, and the combination of B. subtilis and YCW), pathogen challenge (without or with Clostridium perfringens challenge), and their interactive effects.3. C. perfringens infection increased intestinal lesions scores, damaged intestinal histomorphology, increased serum endotoxin concentration, cytokine mRNA expression and intestinal population of C. perfringens and Escherichia coli and decreased ileal bifidobacteria numbers. The 4 additives decreased serum endotoxin. Zinc bacitracin tended to decrease cytokine mRNA expression and the intestinal number of C. perfringens and E. coli. B. subtilis, YCW and their combination increased cytokine mRNA expression. B. subtilis and YCW decreased the number of C. perfringens and E. coli in the ileum, and their combination decreased pathogens numbers in the ileum and caecum.4. In conclusion, B. subtilis, YCW and their combination improved the intestinal health of NE-infected broilers, and could be potential alternatives to antibiotics.

High Fat Diets Induce Colonic Epithelial Cell Stress and Inflammation that is Reversed by IL-22.

Prolonged high fat diets (HFD) induce low-grade chronic intestinal inflammation in mice, and diets high in saturated fat are a risk factor for the development of human inflammatory bowel diseases. We hypothesized that HFD-induced endoplasmic reticulum (ER)/oxidative stress occur in intestinal secretory goblet cells, triggering inflammatory signaling and reducing synthesis/secretion of proteins that form the protective mucus barrier. In cultured intestinal cells non-esterified long-chain saturated fatty acids directly increased oxidative/ER stress leading to protein misfolding. A prolonged HFD elevated the intestinal inflammatory cytokine signature, alongside compromised mucosal barrier integrity with a decrease in goblet cell differentiation and Muc2, a loss in the tight junction protein, claudin-1 and increased serum endotoxin levels. In Winnie mice, that develop spontaneous colitis, HFD-feeding increased ER stress, further compromised the mucosal barrier and increased the severity of colitis. In obese mice IL-22 reduced ER/oxidative stress and improved the integrity of the mucosal barrier, and reversed microbial changes associated with obesity with an increase in Akkermansia muciniphila. Consistent with epidemiological studies, our experiments suggest that HFDs are likely to impair intestinal barrier function, particularly in early life, which partially involves direct effects of free-fatty acids on intestinal cells, and this can be reversed by IL-22 therapy.

Oral Administration of P. gingivalis Induces Dysbiosis of Gut Microbiota and Impaired Barrier Function Leading to Dissemination of Enterobacteria to the Liver.

Although periodontitis has been implicated as a risk factor for various systemic diseases, the precise mechanisms by which periodontitis induces systemic disease remain to be elucidated. We have previously revealed that repeated oral administration of Porphyromonas gingivalis elicits endotoxemia via changes in the gut microbiota of the ileum, and thereby induces systemic inflammation and insulin resistance. However, it is not clear to what extent a single administration of P. gingivalis could affect gut microbiota composition, gut barrier function, and subsequent influx of gut microbiota into the liver. Therefore, in the present study, C57BL/6 mice were orally administered P. gingivalis (strain W83) once and compared to sham-inoculated mice. The phylogenetic structure and diversity of microbial communities in the gut and liver were analyzed by pyrosequencing the 16S ribosomal RNA genes. Serum endotoxin activity was determined by a Limulus amebocyte lysate test. Gene expression in the intestine and expression of 16S rRNA genes in the blood and liver were examined by quantitative polymerase chain reaction. Administration of P. gingivalis significantly altered gut microbiota, with an increased proportion of phylum Bacteroidetes, a decreased proportion of phylum Firmicutes, and increased serum endotoxin levels. In the intestinal tissues, gene expression of tjp-1 and occludin, which are involved in intestinal permeability, were downregulated. Higher amounts of bacterial DNA were detected in the liver of infected mice. Importantly, changes in gut microbiota preceded systemic inflammatory changes. These results further support the idea that disturbance of the gut microbiota composition by orally derived periodontopathic bacteria may be a causal mechanism linking periodontitis and systemic disease.

Micro-RNA-155 deficiency prevents alcohol-induced serum endotoxin increase and small bowel inflammation in mice.

Chronic alcohol impairs gut barrier function and induces inflammatory cytokines. The effects of acute alcohol binge on the gut are partially understood. Micro-RNA-155 (miR-155), a modulator of cytokine and T-cell immune response in the gut, stabilizes tumor necrosis factor-α (TNFα) mRNA. Here, we investigated the role of the inflammation modulator miR-155 as well as the effects of acute binge and chronic alcohol feeding in the small bowel (SB) in mice. For the acute alcohol binge, wild-type (WT) mice received 5g/kg 50% alcohol/d or equal amount of water oral gavage for 3days. WT and miR-155-deficient (miR-155-knockout [KO]) mice received ethanol containing Lieber-DeCarli or isocaloric control diet for 5weeks. MiR-155, antimicrobial peptide, regenerating islet-derived 3-beta (Reg3b), inflammation markers, Src homology 2-containing inositol phosphatase-1 (SHIP1), TNFα, and nuclear factor-κB (NF-κB) were measured in proximal intestinal tissue. Endotoxin was measured in the serum. Acute alcohol binge enhanced, whereas chronic alcohol feeding decreased, Reg3b mRNA and protein levels in the SB. Both acute binge and chronic alcohol feeding increased serum endotoxin levels, intestinal NF-κB activation and TNFα mRNA levels. However, TNFα protein and miR-155 were increased only after chronic alcohol feeding in the SB. Furthermore, miR-155-KO mice were protected from chronic alcohol-induced increase in serum endotoxin, intestinal TNFα, and NF-κB activation. Also, alcohol-fed miR-155-KO mice had no decrease of Reg3b and SHIP1 levels. These results demonstrate that both acute binge and chronic ethanol administration result in increased serum-endotoxin levels. Our study identifies a novel role for miR-155 in chronic alcohol-induced intestinal inflammation and barrier dysfunction.

Influence of thermally oxidized vegetable oils and animal fats on intestinal barrier function and immune variables in young pigs.

To evaluate the effect of feeding thermally oxidized lipids on metabolic oxidative status, gut barrier function, and immune response of young pigs, 108 barrows (6.67 ± 0.03 kg BW) were assigned to 12 dietary treatments in a 4 × 3 factorial arrangement in addition to a corn-soybean meal control diet. Main effects were 4 lipid sources (corn oil [CN], canola oil [CA], poultry fat [PF], and tallow [TL]) and 3 oxidation levels (original lipids [OL], slow oxidation [SO] of lipids heated for 72 h at 95°C, or rapid oxidation [RO] of lipids heated for 7 h at 185°C). Pigs were provided ad libitum access to diets for 28 d followed by controlled feed intake for 10 d. After a 24-h fast on d 38, serum was collected and analyzed for α-tocopherol (α-T), thiobarbituric acid reactive substances (TBARS), endotoxin, haptoglobin, IgA, and IgG. On the same day following serum collection, lactulose and mannitol were fed and subsequently measured in the urine to evaluate gut permeability. There was a source × peroxidation interaction for serum α-T concentration where pigs fed SO or RO had decreased (P < 0.05) serum α-T concentration compared with pigs fed OL in CA and CN diets but not in pigs fed PF and TL diets. There was no source × peroxidation interaction for serum TBARS, but among all lipid sources, pigs fed SO or RO lipids had increased (P < 0.05) serum TBARS compared with pigs fed OL. In addition, pigs fed CN or CA had greater (P < 0.05) serum TBARS compared with pigs fed PF or TL diets. There were no lipid source × peroxidation level interaction or lipid source or peroxidation level effects on serum endotoxin, haptoglobin, IgA, or IgG. Pigs fed lipid supplemented diets tended to have increased serum endotoxin (P = 0.06), IgA (P = 0.10), and IgG (P = 0.09) compared with pigs fed the control diet. There were no lipid source × peroxidation level interaction or lipid source or peroxidation level effects on urinary TBARS and lactulose to mannitol ratio. Compared with pigs fed the control diet, pigs fed diets containing lipids had a lower lactulose to mannitol ratio (P < 0.01). In conclusion, feeding weaning pigs diets containing 10% thermally oxidized lipids for 38 d, especially vegetable oils containing greater concentrations of PUFA, appeared to impair oxidative status but had little influence on gut barrier function or serum immunity parameters.

Acute Binge Drinking Increases Serum Endotoxin and Bacterial DNA Levels in Healthy Individuals

Binge drinking, the most common form of alcohol consumption, is associated with increased mortality and morbidity; yet, its biological consequences are poorly defined. Previous studies demonstrated that chronic alcohol use results in increased gut permeability and increased serum endotoxin levels that contribute to many of the biological effects of chronic alcohol, including alcoholic liver disease. In this study, we evaluated the effects of acute binge drinking in healthy adults on serum endotoxin levels. We found that acute alcohol binge resulted in a rapid increase in serum endotoxin and 16S rDNA, a marker of bacterial translocation from the gut. Compared to men, women had higher blood alcohol and circulating endotoxin levels. In addition, alcohol binge caused a prolonged increase in acute phase protein levels in the systemic circulation. The biological significance of the in vivo endotoxin elevation was underscored by increased levels of inflammatory cytokines, TNFα and IL-6, and chemokine, MCP-1, measured in total blood after in vitro lipopolysaccharide stimulation. Our findings indicate that even a single alcohol binge results in increased serum endotoxin levels likely due to translocation of gut bacterial products and disturbs innate immune responses that can contribute to the deleterious effects of binge drinking.

Heat Stress Reduces Intestinal Barrier Integrity and Favors Intestinal Glucose Transport in Growing Pigs

Excessive heat exposure reduces intestinal integrity and post-absorptive energetics that can inhibit wellbeing and be fatal. Therefore, our objectives were to examine how acute heat stress (HS) alters intestinal integrity and metabolism in growing pigs. Animals were exposed to either thermal neutral (TN, 21°C; 35–50% humidity; n = 8) or HS conditions (35°C; 24–43% humidity; n = 8) for 24 h. Compared to TN, rectal temperatures in HS pigs increased by 1.6°C and respiration rates by 2-fold (P<0.05). As expected, HS decreased feed intake by 53% (P<0.05) and body weight (P<0.05) compared to TN pigs. Ileum heat shock protein 70 expression increased (P<0.05), while intestinal integrity was compromised in the HS pigs (ileum and colon TER decreased; P<0.05). Furthermore, HS increased serum endotoxin concentrations (P = 0.05). Intestinal permeability was accompanied by an increase in protein expression of myosin light chain kinase (P<0.05) and casein kinase II-α (P = 0.06). Protein expression of tight junction (TJ) proteins in the ileum revealed claudin 3 and occludin expression to be increased overall due to HS (P<0.05), while there were no differences in claudin 1 expression. Intestinal glucose transport and blood glucose were elevated due to HS (P<0.05). This was supported by increased ileum Na+/K+ ATPase activity in HS pigs. SGLT-1 protein expression was unaltered; however, HS increased ileal GLUT-2 protein expression (P = 0.06). Altogether, these data indicate that HS reduce intestinal integrity and increase intestinal stress and glucose transport.

Anti-Inflammatory Mechanisms of Apolipoprotein A-I Mimetic Peptide in Acute Respiratory Distress Syndrome Secondary to Sepsis

Acute respiratory distress syndrome (ARDS) due to sepsis has a high mortality rate with limited treatment options. High density lipoprotein (HDL) exerts innate protective effects in systemic inflammation. However, its role in ARDS has not been well studied. Peptides such as L-4F mimic the secondary structural features and functions of apolipoprotein (apo)A-I, the major protein component of HDL. We set out to measure changes in HDL in sepsis-mediated ARDS patients, and to study the potential of L-4F to prevent sepsis-mediated ARDS in a rodent model of lipopolysaccharide (LPS)-mediated acute lung injury, and a combination of primary human leukocytes and human ARDS serum. We also analyzed serum from non-lung disease intubated patients (controls) and sepsis-mediated ARDS patients. Compared to controls, ARDS demonstrates increased serum endotoxin and IL-6 levels, and decreased HDL, apoA-I and activity of anti-oxidant HDL-associated paraoxanase-1. L-4F inhibits the activation of isolated human leukocytes and neutrophils by ARDS serum and LPS in vitro. Further, L-4F decreased endotoxin activity and preserved anti-oxidant properties of HDL both in vitro and in vivo. In a rat model of severe endotoxemia, L-4F significantly decreased mortality and reduces lung and liver injury, even when administered 1 hour post LPS. Our study suggests the protective role of the apoA-I mimetic peptide L-4F in ARDS and gram-negative endotoxemia and warrant further clinical evaluation. The main protective mechanisms of L-4F are due to direct inhibition of endotoxin activity and preservation of HDL anti-oxidant activity.

An opportunistic pathogen isolated from the gut of an obese human causes obesity in germfree mice

Lipopolysaccharide endotoxin is the only known bacterial product which, when subcutaneously infused into mice in its purified form, can induce obesity and insulin resistance via an inflammation-mediated pathway. Here we show that one endotoxin-producing bacterium isolated from a morbidly obese human's gut induced obesity and insulin resistance in germfree mice. The endotoxin-producing Enterobacter decreased in relative abundance from 35% of the volunteer's gut bacteria to non-detectable, during which time the volunteer lost 51.4 kg of 174.8 kg initial weight and recovered from hyperglycemia and hypertension after 23 weeks on a diet of whole grains, traditional Chinese medicinal foods and prebiotics. A decreased abundance of endotoxin biosynthetic genes in the gut of the volunteer was correlated with a decreased circulating endotoxin load and alleviated inflammation. Mono-association of germfree C57BL/6J mice with strain Enterobacter cloacae B29 isolated from the volunteer's gut induced fully developed obesity and insulin resistance on a high-fat diet but not on normal chow diet, whereas the germfree control mice on a high-fat diet did not exhibit the same disease phenotypes. The Enterobacter-induced obese mice showed increased serum endotoxin load and aggravated inflammatory conditions. The obesity-inducing capacity of this human-derived endotoxin producer in gnotobiotic mice suggests that it may causatively contribute to the development of obesity in its human host.

Profound impact of gut homeostasis on chemically-induced pro-tumorigenic inflammation and hepatocarcinogenesis in rats

Due to its anatomic connection, the liver is constantly exposed to gut-derived bacterial products or metabolites. Disruption of gut homeostasis is associated with many human diseases. The aim of this study was to determine the role of gut homeostasis in initiation and progression of hepatocellular carcinoma (HCC). Disruption of intestinal homeostasis by penicillin or dextran sulfate sodium (DSS) and its restoration by probiotics were applied in a diethylnitrosamine (DEN) model of rat hepatocarcinogenesis. Patients with liver cirrhosis and HCC had significantly increased serum endotoxin levels. Chronic DEN treatment of rats was associated with an imbalance of subpopulations of the gut microflora including a significant suppression of Lactobacillus species, Bifidobacterium species and Enterococcus species as well as intestinal inflammation. Induction of enteric dysbacteriosis or intestinal inflammation by penicillin or DSS, respectively, significantly promoted tumor formation. Administration of probiotics dramatically mitigated enteric dysbacteriosis, ameliorated intestinal inflammation, and most importantly, decreased liver tumor growth and multiplicity. Interestingly, probiotics not only inhibited the translocation of endotoxin, which bears pathogen-associated molecular patterns (PAMPs) but also the activation of damage-associated molecular patterns (DAMPs) such as high-mobility group box 1 (HMGB1). As a result, the production of pro- and anti-inflammatory cytokines was skewed in favor of a reduced tumorigenic inflammation in the liver. The data highlights the importance of gut homeostasis in the pathogenesis of HCC. Modulation of the gut microbiota by probiotics may represent a new avenue for therapeutic intervention to treat or prevent HCC development.

Intake of trans fatty acids during gestation and lactation leads to hypothalamic inflammation via TLR4/NFκBp65 signaling in adult offspring

We examined whether feeding pregnant and lactating rats with hydrogenated vegetable fats rich in trans fatty acids led to an increase in serum endotoxin levels and inflammation and to impaired satiety-sensing pathways in the hypothalamus of 90-day-old offspring. Pregnant and lactating Wistar rats were fed either a standard chow (Control) or one enriched with hydrogenated vegetable fat (Trans). Upon weaning, the male offspring were divided in two groups: Control-Control (CC), mothers and offspring fed the control diet; and Trans-Control (TC), mothers fed the trans diet, and offspring fed the control diet. The offspring's food intake and body weight were quantified weekly and the offspring were killed on the 90th day of life by decapitation. The blood and hypothalamus were collected from the offspring. Food intake and body weight were higher in the TC rats than in the CC rats. TC rats had increased serum endotoxin levels and increased hypothalamic cytokines, IL-6, TNF-α and IL1-β, concentrations (P<.05). TLR4, NFκBp65 and MyD88 were higher (P<.05) in the TC rats than in the CC rats. AdipoR1 was lower in the TC rats than in the CC rats. Thus, the present study shows that the mothers' hydrogenated vegetable fat intake during pregnancy and lactation led to hypothalamic inflammation and impaired satiety-sensing, which promotes deleterious metabolic consequences such as obesity, even after the withdrawal of the causal factor. In other words, the effect remains after the consumption of the standard chow by offspring.

Up-regulation of MicroRNA-155 in Macrophages Contributes to Increased Tumor Necrosis Factor α (TNFα) Production via Increased mRNA Half-life in Alcoholic Liver Disease

Activation of Kupffer cells (KCs) by gut-derived lipopolysaccharide (LPS) and Toll-Like Receptors 4 (TLR4)-LPS-mediated increase in TNFα production has a central role in the pathogenesis of alcoholic liver disease. Micro-RNA (miR)-125b, miR-146a, and miR-155 can regulate inflammatory responses to LPS. Here we evaluated the involvement of miRs in alcohol-induced macrophage activation. Chronic alcohol treatment in vitro resulted in a time-dependent increase in miR-155 but not miR-125b or miR-146a levels in RAW 264.7 macrophages. Furthermore, alcohol pretreatment augmented LPS-induced miR-155 expression in macrophages. We found a linear correlation between alcohol-induced increase in miR-155 and TNFα induction. In a mouse model of alcoholic liver disease, we found a significant increase in both miR-155 levels and TNFα production in isolated KCs when compared with pair-fed controls. The mechanistic role of miR-155 in TNFα regulation was indicated by decreased TNFα levels in alcohol-treated macrophages after inhibition of miR-155 and by increased TNFα production after miR-155 overexpression, respectively. We found that miR-155 affected TNFα mRNA stability because miR-155 inhibition decreased whereas miR-155 overexpression increased TNFα mRNA half-life. Using the NF-κB inhibitors, MG-132 or Bay11-7082, we demonstrated that NF-κB activation mediated the up-regulation of miR-155 by alcohol in KCs. In conclusion, our novel data demonstrate that chronic alcohol consumption increases miR-155 in macrophages via NF-κB and the increased miR-155 contributes to alcohol-induced elevation in TNFα production via increased mRNA stability.

Increased Serum Endotoxin and Elevated CD14 and IL-1&amp;#946; Expression in a Rat Model of Cerebrogenic Multiple Organ Dysfunction Syndrome

To study the mechanisms underlying cerebrogenic multiple organ dysfunction syndrome (CMODS) through investigation of endotoxin levels and the expression of endotoxin receptor CD14 and interleukin IL-1beta mRNAs in a rat CMODS model. Acute cerebral hemorrhage was induced in Wistar rats by focal intracerebral injection of collagenase into the caudate nucleus. Serum endotoxin levels were quantitated using a chromogenic limulus lysate method; CD14 endotoxin receptor mRNA and IL-1beta mRNA levels in lung and intestine were determined by in situ hybridization. Serum endotoxin levels increased after 12 h, reaching a peak after 24 h, and declined to control levels at 72 h. The increase was statistically significant (P<0.05) compared to unoperated controls and the sham-operated group respectively. CD14 mRNA in lung and intestine increased after 12 h, peaked after 24-36 h, and then declined after 48 h. IL-1beta mRNA levels were also increased in lung and intestine (P<0.05), peaking at 36 h and declining thereafter. Expression levels of both CD14 and IL-1beta mRNAs correlated significantly with serum endotoxin levels (Plt;0.01). We conclude that acute cerebral hemorrhage results in endotoxemia and widespread increases in CD14 and IL-1beta expression. We suggest that acute cerebrovascular challenge leads to a stress/shock response that compromises the intestinal mucosal barrier. In turn, this allows endotoxin translocation into the body that provokes the release of pro-inflammatory lymphokines, leading to a systemic inflammatory response syndrome (SIRS) that culminates in multiple organ dysfunction.

Susceptibility to gut leakiness: a possible mechanism for endotoxaemia in non‐alcoholic steatohepatitis

One of the proposed second hit mechanisms in the pathophysiology of non-alcoholic steatohepatitis (NASH) is hepatic oxidative stress triggered by elevated levels of endotoxin. We investigated one possible mechanism for the endotoxaemia--disruption of intestinal barrier integrity. We enrolled 16 subjects with fatty liver (10 NASH; 6 steatosis) and 12 healthy subjects. Steatosis and NASH were diagnosed by liver biopsy using the Brunt criteria. Gastrointestinal permeability was measured using urinary excretion of 5-h lactulose/mannitol (L/M) ratio and 24-h sucralose. Permeability testing was repeated after aspirin challenge. Groups had similar baseline urinary 0-5 h L/M ratio (small bowel permeability) and 0-24 h sucralose (whole-gut permeability). Aspirin increased 0-5 h urinary L/M in most subjects. In contrast, aspirin significantly increased whole-gut permeability only in NASH subjects. In fact, the major increase in the urinary sucralose occurred in the 6-24 h samples, which points towards the colon as the major site responsible for aspirin-induced leakiness in NASH patients. Serum endotoxin levels were significantly higher in NASH subjects. Our findings suggest that aspirin acts on the colon to unmask a susceptibility to gut leakiness in patients with NASH. This effect may be the underlying mechanism for increased serum endotoxin, which is the second hit (after altered lipid metabolism) that is required to initiate a necroinflammatory cascade in hepatocytes which are already primed with obesity-induced abnormal lipid homoeostasis.