Search

Background: Cognitive dysfunction caused by infection frequently emerges as a complication in sepsis survivor patients. However, a comprehensive understanding of its pathogenesis remains elusive., Methods: In our in vivo experiments, an animal model of endotoxemia was employed, utilizing the Novel Object Recognition Test and Morris Water Maze Test to assess cognitive function. Various techniques, including immunofluorescent staining, Western blotting, blood‒brain barrier permeability assessment, Limulus Amebocyte Lysate (LAL) assay, and Proximity-ligation assay, were employed to identify brain pathological injury and neuroinflammation. To discern the role of Caspase-11 (Casp11) in hematopoietic or non-hematopoietic cells in endotoxemia-induced cognitive decline, bone marrow chimeras were generated through bone marrow transplantation (BMT) using wild-type (WT) and Casp11-deficient mice. In vitro studies involved treating BV2 cells with E. coli-derived outer membrane vesicles to mimic in vivo conditions., Results: Our findings indicate that the deficiency of Casp11-GSDMD signaling pathways reverses infection-induced cognitive dysfunction. Moreover, cognitive dysfunction can be ameliorated by blocking the IL-1 effect. Mechanistically, the absence of Casp11 signaling significantly mitigated blood‒brain barrier leakage, microglial activation, and synaptic damage in the hippocampal CA3 region, ultimately leading to improved cognitive function., Conclusion: This study unveils the crucial contribution of Casp11 and GSDMD to cognitive impairments and spatial memory loss in a murine sepsis model. Targeting Casp11 signaling emerges as a promising strategy for preventing or treating cognitive dysfunction in patients with severe infections., (© 2024. The Author(s).)

Metabolic endotoxemia is a severe health problem for residents in developed countries who follow a Western diet, disrupting intestinal microbiota and the whole organism's homeostasis. Although the effect of endotoxin on the human immune system is well known, its long-term impact on the human body, lasting many months or even years, is unknown. This is due to the difficulty of conducting in vitro and in vivo studies on the prolonged effect of endotoxin on the central nervous system. In this article, based on the available literature, we traced the path of endotoxin from the intestines to the blood through the intestinal epithelium and factors promoting the development of metabolic endotoxemia. The presence of endotoxin in the bloodstream and the inflammation it induces may contribute to lowering the blood-brain barrier, potentially allowing its penetration into the central nervous system; although, the theory is still controversial. Microglia, guarding the central nervous system, are the first line of defense and respond to endotoxin with activation, which may contribute to the development of neurodegenerative diseases. We traced the pro-inflammatory role of endotoxin in neurodegenerative diseases and its impact on the epigenetic regulation of microglial phenotypes.

Introduction: The mechanism underlying radiation-induced gut microbiota dysbiosis is undefined. This study examined the effect of radiation on the intestinal Paneth cell α-defensin expression and its impact on microbiota composition and mucosal tissue injury and evaluated the radio-mitigative effect of human α-defensin 5 (HD5)., Methods: Adult mice were subjected to total body irradiation, and Paneth cell α-defensin expression was evaluated by measuring α-defensin mRNA by RT-PCR and α-defensin peptide levels by mass spectrometry. Vascular-to-luminal flux of FITC-inulin was measured to evaluate intestinal mucosal permeability and endotoxemia by measuring plasma lipopolysaccharide. HD5 was administered in a liquid diet 24 hours before or after irradiation. Gut microbiota was analyzed by 16S rRNA sequencing. Intestinal epithelial junctions were analyzed by immunofluorescence confocal microscopy and mucosal inflammatory response by cytokine expression. Systemic inflammation was evaluated by measuring plasma cytokine levels., Results: Ionizing radiation reduced the Paneth cell α-defensin expression and depleted α-defensin peptides in the intestinal lumen. α-Defensin down-regulation was associated with the time-dependent alteration of gut microbiota composition, increased gut permeability, and endotoxemia. Administration of human α-defensin 5 (HD5) in the diet 24 hours before irradiation (prophylactic) significantly blocked radiation-induced gut microbiota dysbiosis, disruption of intestinal epithelial tight junction and adherens junction, mucosal barrier dysfunction, and mucosal inflammatory response. HD5, administered 24 hours after irradiation (treatment), reversed radiation-induced microbiota dysbiosis, tight junction and adherens junction disruption, and barrier dysfunction. Furthermore, HD5 treatment also prevents and reverses radiation-induced endotoxemia and systemic inflammation., Conclusion: These data demonstrate that radiation induces Paneth cell dysfunction in the intestine, and HD5 feeding prevents and mitigates radiation-induced intestinal mucosal injury, endotoxemia, and systemic inflammation., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Shukla, Rao, Meena, Giorgianni, Lee, Raju, Shashikanth, Shekhar, Beranova, Balazs, Tigyi, Gosain and Rao.)

Vitamin D insufficiency induces calcification disorder of bone or a decrease in bone mineral density, increasing the risk of fracture. Alkaline phosphatase (ALP) activity, a differentiation marker for intestinal epithelial cells, is regulated by vitamin D. It has also been suggested that ALP may prevent metabolic endotoxemia by dephosphorylating lipopolysaccharide. We hypothesized that vitamin D restriction and/or a high-fat diet influences ALP activity in each tissue and serum lipopolysaccharide concentrations and increases the risk of metabolic endotoxemia. Eleven-week-old female rats were divided into 4 groups: basic control diet (Cont.), basic control diet with vitamin D restriction (DR), high-fat diet (HF), and high-fat diet with vitamin D restriction (DRHF) groups. They were acclimated for 28 days. The results of 2-way analysis of variance showed that intestinal ALP activity, which may contribute to an improvement in phosphate/lipid metabolism and longevity, in the high-fat diet groups (HF and DRHF) was higher than in the low-fat diet groups (Cont. and DR). ALP activity in the vitamin D-restricted groups (DR and DRHF) was lower than in the vitamin D-sufficient groups (Cont. and HF). Furthermore, serum endotoxin concentrations were significantly higher in the high-fat diet groups (HF and DRHF) than in the low-fat diet groups (Cont. and DR). In the vitamin D-restricted groups (DR and DRHF), serum endotoxin concentrations were also significantly higher than in the vitamin D-sufficient groups (Cont. and HF). These results suggest that vitamin D restriction and/or a high-fat diet increases the risk of metabolic endotoxemia., Competing Interests: Declaration of Competing Interest There are no conflicts of interest to disclose., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Aims/hypothesis: Translocation of bacterial debris from the gut causes metabolic endotoxemia (ME) that results in insulin resistance, and may be on the causal pathway to obesity-related type 2 diabetes. To guide interventions against ME we tested two hypothesised mechanisms for lipopolysaccharide (LPS) ingress: a leaky gut and chylomicron-associated transfer following a high-fat meal., Methods: In lean women (n = 48; fat mass index (FMI) 9.6 kg/m 2 ), women with obesity (n = 62; FMI 23.6 kg/m 2 ) and women with obesity-diabetes (n = 38; FMI 24.9 kg/m 2 ) we used the lactulose-mannitol dual-sugar permeability test (LM ratio) to assess gut integrity. Markers of ME (LPS, EndoCAb IgG and IgM, IL-6, CD14 and lipoprotein binding protein) were assessed at baseline, 2 h and 5 h after a standardised 49 g fat-containing mixed meal. mRNA expression of markers of inflammation, macrophage activation and lipid metabolism were measured in peri-umbilical adipose tissue (AT) biopsies., Results: The LM ratio did not differ between groups. LPS levels were 57% higher in the obesity-diabetes group (P < 0.001), but, contrary to the chylomicron transfer hypothesis, levels significantly declined following the high-fat challenge. EndoCAb IgM was markedly lower in women with obesity and women with obesity-diabetes. mRNA levels of inflammatory markers in adipose tissue were consistent with the prior concept that fat soluble LPS in AT attracts and activates macrophages., Conclusions/interpretation: Raised levels of LPS and IL-6 in women with obesity-diabetes and evidence of macrophage activation in adipose tissue support the concept of metabolic endotoxemia-mediated inflammation, but we found no evidence for abnormal gut permeability or chylomicron-associated post-prandial translocation of LPS. Instead, the markedly lower EndoCAb IgM levels indicate a failure in sequestration and detoxification., (© 2022. The Author(s).)

Background: Endotoxemia is related to worse clinical outcomes in acute liver failure (ALF), but its management remains unsatisfactory. In this study, we aimed to assess whether the application of bone marrow mesenchymal stem cells (BMSCs) could eliminate endotoxemia and protect rats against ALF induced by thioacetamide (TAA)., Methods: BMSCs were isolated from rats and identified by the specific morphology, differentiation potential, and surface markers. The optimal dose of TAA for this study was explored and TAA-induced ALF rats were randomized to three groups: the normal control group (Saline), ALF group (TAA + Saline), and BMSCs-treated group (TAA + BMSCs). The intestinal migration and differentiation of BMSCs was tracked in vivo, and intestinal permeability, endotoxin and inflammatory cytokines, histology, and mortality were analyzed. Moreover, we added the inhibitor of the PI3K/AKT/mTOR signaling pathway into the co-culture system of BMSCs with enterocytes and then performed CK and Villin expression experiments to assess the role of PI3K/AKT/mTOR signal pathway in the intestinal differentiation of BMSCs., Results: BMSCs migrated to the intestinal injury sites and differentiated into enterocytes, intestinal permeability was decreased compared with the ALF group. The higher expression of endotoxin and inflammatory cytokines were reversed after BMSCs transplantation in rats with ALF. Mortality and intestinal lesion were significantly decreased. Blocking the PI3K/AKT/mTOR signal pathway inhibited BMSCs' intestinal differentiation in vitro., Conclusion: BMSCs can eliminate endotoxemia and reduce mortality in rats with ALF, and the PI3K/AKT/mTOR signal pathway is involved in intestinal differentiation. BMSCs transplantation could be a potential candidate for the treatment of endotoxemia in ALF., (© 2022. The Author(s).)

TLR4 signaling via endotoxemia in macrophages promotes macrophage transition to the inflammatory phenotype through NLRP3 inflammasome activation. This transition event has the potential to trigger acute lung injury (ALI). However, relatively little is known about the regulation of NLRP3 and its role in the pathogenesis of ALI. Here we interrogated the signaling pathway activated by CD38, an ectoenzyme expressed in macrophages, in preventing ALI through suppressing NLRP3 activation. Wild-type and Cd38 -knockout ( Cd38 -/- ) mice were used to assess inflammatory lung injury, and isolated macrophages were used to delineate underlying TLR4 signaling pathway. We showed that CD38 suppressed TLR4 signaling in macrophages by inhibiting Bruton's tyrosine kinase (Btk) through the recruitment of Src homology-2 domain containing protein tyrosine phosphatase-2 (SHP2) and resulting in the dephosphorylation of activated Btk. Cd38 -/- mice show enhanced lung polymorphonuclear leukocyte extravasation and severe lung injury. LPS- or polymicrobial sepsis-induced mortality in Cd38 -/- mice were markedly augmented compared with wild types. CD38 in macrophages functioned by inhibiting Btk activation through activation of SHP2 and resulting dephosphorylation of Btk, and thereby preventing activation of downstream targets NF-κB and NLRP3. Cd38 -/- macrophages displayed markedly increased activation of Btk, NF-κB, and NLRP3, whereas in vivo administration of the Btk inhibitor ibrutinib (a Food and Drug Administration-approved drug) prevented augmented TLR4-induced inflammatory lung injury seen in Cd38 -/- mice. Our findings together show upregulation of CD38 activity and inhibition of Btk activation downstream of TLR4 activation as potential strategies to prevent endotoxemic ALI.

Lipopolysaccharide (LPS)-induced endotoxemia induces an acute systemic inflammatory response that mimics some important features of sepsis, the disease with the highest mortality rate worldwide. In this work, we have analyzed a murine model of endotoxemia based on a single intraperitoneal injection of 5 mg/kg of LPS. We took advantage of galectin-3 (Gal3) knockout mice and found that the absence of Gal3 decreased the mortality rate oflethal endotoxemia in the first 80 h after the administration of LPS, along with a reduction in the tissular damage in several organs measured by electron microscopy. Using flow cytometry, we demonstrated that, in control conditions, peripheral immune cells, especially monocytes, exhibited high levels of Gal3, which were early depleted in response to LPS injection, thus suggesting Gal3 release under endotoxemia conditions. However, serum levels of Gal3 early decreased in response to LPS challenge (1 h), an indication that Gal3 may be extravasated to peripheral organs. Indeed, analysis of Gal3 in peripheral organs revealed a robust up-regulation of Gal3 36 h after LPS injection. Taken together, these results demonstrate the important role that Gal3 could play in the development of systemic inflammation, a well-established feature of sepsis, thus opening new and promising therapeutic options for these harmful conditions.

Mechanical ventilation (MV) is essential for patients with sepsis-related respiratory failure but can cause ventilator-induced diaphragm dysfunction (VIDD), which involves diaphragmatic myofiber atrophy and contractile inactivity. Mitochondrial DNA, oxidative stress, mitochondrial dynamics, and biogenesis are associated with VIDD. Hypoxia-inducible factor 1α (HIF-1α) is crucial in the modulation of diaphragm immune responses. The mechanism through which HIF-1α and mitochondria affect sepsis-related diaphragm injury is unknown. We hypothesized that MV with or without endotoxin administration would aggravate diaphragmatic and mitochondrial injuries through HIF-1α. C57BL/6 mice, either wild-type or HIF-1α-deficient, were exposed to MV with or without endotoxemia for 8 h. MV with endotoxemia augmented VIDD and mitochondrial damage, which presented as increased oxidative loads, dynamin-related protein 1 level, mitochondrial DNA level, and the expressions of HIF-1α and light chain 3-II. Furthermore, disarrayed myofibrils; disorganized mitochondria; increased autophagosome numbers; and substantially decreased diaphragm contractility, electron transport chain activities, mitofusin 2, mitochondrial transcription factor A, peroxisome proliferator activated receptor-γ coactivator-1α, and prolyl hydroxylase domain 2 were observed ( p < 0.05). Endotoxin-stimulated VIDD and mitochondrial injuries were alleviated in HIF-1α-deficient mice ( p < 0.05). Our data revealed that endotoxin aggravated MV-induced diaphragmatic dysfunction and mitochondrial damages, partially through the HIF-1α signaling pathway.

Aims: To characterize neuroinflammatory and gut dysbiosis signatures that accompany exaggerated exercise fatigue and cognitive/mood deficits in a mouse model of Gulf War Illness (GWI)., Methods: Adult male C57Bl/6N mice were exposed for 28 d (5 d/wk) to pyridostigmine bromide (P.O.) at 6.5 mg/kg/d, b.i.d. (GW1) or 8.7 mg/kg/d, q.d. (GW2); topical permethrin (1.3 mg/kg), topical N,N-diethyl-meta-toluamide (33%) and restraint stress (5 min). Animals were phenotypically evaluated as described in an accompanying article [124] and sacrificed at 6.6 months post-treatment (PT) to allow measurement of brain neuroinflammation/neuropathic pain gene expression, hippocampal glial fibrillary acidic protein, brain Interleukin-6, gut dysbiosis and serum endotoxin., Key Findings: Compared to GW1, GW2 showed a more intense neuroinflammatory transcriptional signature relative to sham stress controls. Interleukin-6 was elevated in GW2 and astrogliosis in hippocampal CA1 was seen in both GW groups. Beta-diversity PCoA using weighted Unifrac revealed that gut microbial communities changed after exposure to GW2 at PT188. Both GW1 and GW2 displayed systemic endotoxemia, suggesting a gut-brain mechanism underlies the neuropathological signatures. Using germ-free mice, probiotic supplementation with Lactobacillus reuteri produced less gut permeability than microbiota transplantation using GW2 feces., Significance: Our findings demonstrate that GW agents dose-dependently induce differential neuropathology and gut dysbiosis associated with cognitive, exercise fatigue and mood GWI phenotypes. Establishment of a comprehensive animal model that recapitulates multiple GWI symptom domains and neuroinflammation has significant implications for uncovering pathophysiology, improving diagnosis and treatment for GWI., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

Introduction: Uncontrolled systemic inflammation may occur in severe coronavirus disease 19 (COVID-19). We have previously shown that endotoxemia, presumably from the gut, may complicate COVID-19. However, the role of endotoxin adsorbent (EA) therapy to mitigate organ dysfunction in COVID-19 has not been explored., Methods: We conducted a retrospective observational study in COVID-19 patients who received EA therapy at the King Chulalongkorn Memorial Hospital, Bangkok, Thailand, between March 13 and April 17, 2020. Relevant clinical and laboratory data were collected by inpatient chart review., Results: Among 147 hospitalized COVID-19 patients, 6 patients received EA therapy. All of the 6 patients had severe COVID-19 infection with acute respiratory distress syndrome (ARDS). Among these, 5 of them were mechanically ventilated and 4 had complications of secondary bacterial infection. The endotoxin activity assay (EAA) results of pre-EA therapy ranged from 0.47 to 2.79. The choices of EA therapy were at the discretion of attending physicians. One patient was treated with oXiris® along with continuous renal replacement therapy, and the others received polymyxin B hemoperfusion sessions. All patients have survived and were finally free from the mechanical ventilation as well as had improvement in PaO2/FiO2 ratio and decreased EAA level after EA therapy., Conclusions: We demonstrated the clinical improvement of severe COVID-19 patients with elevated EAA level upon receiving EA therapy. However, the benefit of EA therapy in COVID-19 ARDS is still unclear and needs to be elucidated with randomized controlled study., (© 2021 S. Karger AG, Basel.)

Competition for the amino acid arginine by endothelial nitric-oxide synthase (NOS3) and (pro-)inflammatory NO-synthase (NOS2) during endotoxemia appears essential in the derangement of the microcirculatory flow. This study investigated the role of NOS2 and NOS3 combined with/without citrulline supplementation on the NO-production and microcirculation during endotoxemia. Wildtype (C57BL6/N background; control; n = 36), Nos2 -deficient, ( n = 40), Nos3 -deficient ( n = 39) and Nos2/Nos3 -deficient mice ( n = 42) received a continuous intravenous LPS infusion alone (200 μg total, 18 h) or combined with L-citrulline (37.5 mg, last 6 h). The intestinal microcirculatory flow was measured by side-stream dark field (SDF)-imaging. The jejunal intracellular NO production was quantified by in vivo NO-spin trapping combined with electron spin-resonance (ESR) spectrometry. Amino-acid concentrations were measured by high-performance liquid chromatography (HPLC). LPS infusion decreased plasma arginine concentration in control and Nos3 -/- compared to Nos2 -/- mice. Jejunal NO production and the microcirculation were significantly decreased in control and Nos2 -/- mice after LPS infusion. No beneficial effects of L-citrulline supplementation on microcirculatory flow were found in Nos3 -/- or Nos2 -/- /Nos3 -/- mice. This study confirms that L-citrulline supplementation enhances de novo arginine synthesis and NO production in mice during endotoxemia with a functional NOS3-enzyme (control and Nos2 -/- mice), as this beneficial effect was absent in Nos3 -/- or Nos2 -/- /Nos3 -/- mice.

Introduction: Early diagnosis and treatment can reduce the risk of organ failure and mortality in systemic inflammatory conditions. Heart rate variability (HRV) has potential for early identification of the onset of systemic inflammation, as it may detect changes in sympathetic nervous system activity resulting from the developing inflammatory response before clinical signs appear. With the use of new methodologies, we investigated the onset and kinetics of HRV changes as well as several inflammatory parameters and symptoms during experimental human endotoxemia, a model of systemic inflammation in humans in vivo., Patients and Methods: Healthy volunteers were intravenously administered LPS (n = 15) or placebo (n = 15). HRV was determined using a wireless wearable device, and parameters low to high frequency (LF:HF) ratio, root mean square of the successive differences (RMSSD), and standard deviation of normal-to-normal R-R intervals (SDNN)were calculated through 1-min-rolling 6-min windows. Plasma cytokine levels and flu-like symptoms and vital signs were serially assessed., Results: The increase in LF:HF ratio, reflecting sympathetic predominance, was more pronounced in the LPS group compared to the placebo group, with the difference becoming statistically significant 65 min following LPS administration (1.63 [1.42-1.83] vs. 1.28 [1.11-1.44], P = 0.005). Significant between-group differences in RMSSD and SDNN were observed from 127 to 140 min post-LPS administration onwards, respectively. Plasma cytokine levels showed significant between-group differences staring 60 min post-LPS. For symptom score, heart rate, temperature, and diastolic blood pressure, significant differences compared with the placebo group were observed at 90, 118, 120, and 124 min post-LPS, respectively., Conclusion: In a controlled human model of systemic inflammation, elevations in the LF:HF ratio followed very shortly after elevations in plasma cytokine levels and preceded onset of flu-like symptoms and alterations in vital signs. HRV may represent a promising non-invasive tool for early detection of a developing systemic inflammatory response., Competing Interests: The authors report no funding and conflicts of interest., (Copyright © 2021 by the Shock Society.)

Lipopolysaccharides (LPSs) can promote metabolic endotoxemia, which is considered inflammatory and metabolically detrimental based on Toll-like receptor (TLR)4 agonists, such as Escherichia coli-derived LPS. LPSs from certain bacteria antagonize TLR4 yet contribute to endotoxemia measured by endotoxin units (EUs). We found that E. coli LPS impairs gut barrier function and worsens glycemic control in mice, but equal doses of LPSs from other bacteria do not. Matching the LPS dose from R. sphaeroides and E. coli by EUs reveals that only E. coli LPS promotes dysglycemia and adipose inflammation, delays intestinal glucose absorption, and augments insulin and glucagon-like peptide (GLP)-1 secretion. Metabolically beneficial endotoxemia promoted by R. sphaeroides LPS counteracts dysglycemia caused by an equal dose of E. coli LPS and improves glucose control in obese mice. The concept of metabolic endotoxemia should be expanded beyond LPS load to include LPS characteristics, such as lipid A acylation, which dictates the effect of metabolic endotoxemia., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2021 The Author(s). Published by Elsevier Inc. All rights reserved.)

Bacterial endotoxin is a potent inflammatory antigen abundant in the human intestine. Endotoxins circulate in the blood at low concentrations in all healthy individuals. Elevated levels of circulatory endotoxins may cause inflammation with the development of chronic disease, either affecting metabolism, neurological disease, or resistance to viral and bacterial infections. The most important endotoxin is LPS, being a superantigen. In this narrative review, the effect of various food components to postprandially elevate circulating LPS and inflammatory markers is described. There is evidence that the intake of food enriched in fat, in particular saturated fat, may elevate LPS and pro-inflammatory markers. This occurs in both normal-weight and obese subjects. In obese subjects, inflammatory markers are already elevated before meal consumption. The importance of food choice for endotoxemia and inflammatory response is discussed.

Diet and dietary components have profound effects on the composition of the gut microbiota and are among the most important contributors to the alteration in bacterial flora. This review examines the effects the "Western", "plant-based", "high-fat", "medical ketogenic", and "Mediterranean" diets have on the composition of the gut microbiota in both mice and human subjects. We show that specific dietary components that are commonly found in the "plant-based" and "Mediterranean" diet play a role in shifting the microbial composition. This review further evaluates the bacterial metabolites that are associated with diet, and their role in systemic inflammation and metabolic endotoxemia. Furthermore, the associations between diet/dietary components and altering bacterial composition, may lead to potential therapeutic targets for type II diabetes, obesity, and inflammatory diseases.

Abstract: Leukocyte Nox2 is recognized to have a fundamental microbicidal function in sepsis but the specific role of Nox2 in endothelial cells (EC) remains poorly elucidated. Here, we tested the hypothesis that endothelial Nox2 participates in the pathogenesis of systemic inflammation and hypotension induced by LPS. LPS was injected intravenously in mice with Tie2-targeted deficiency or transgenic overexpression of Nox2. Mice with Tie2-targeted Nox2 deficiency had increased circulating levels of TNF-α, enhanced numbers of neutrophils trapped in lungs, and aggravated hypotension after LPS injection, as compared to control LPS-injected animals. In contrast, Tie2-driven Nox2 overexpression attenuated inflammation and prevented the hypotension induced by LPS. Because Tie2-Cre targets both EC and myeloid cells we generated bone marrow chimeric mice with Nox2 deletion restricted to leukocytes or ECs. Mice deficient in Nox2 either in leukocytes or ECs had reduced LPS-induced neutrophil trapping in the lungs and lower plasma TNF-α levels as compared to control LPS-injected mice. However, the pronounced hypotensive response to LPS was present only in mice with EC-specific Nox2 deletion. Experiments in vitro with human vein or aortic endothelial cells (HUVEC and HAEC, respectively) treated with LPS revealed that EC Nox2 controls NF-κB activation and the transcription of toll-like receptor 4 (TLR4), which is the recognition receptor for LPS. In conclusion, these results suggest that endothelial Nox2 limits NF-κB activation and TLR4 expression, which in turn attenuates the severity of hypotension and systemic inflammation induced by LPS., Competing Interests: The authors report no conflicts of interest., (Copyright © 2020 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the Shock Society.)

Metabolic endotoxemia has been suggested to play a role in the pathophysiology of metaflammation, insulin-resistance and ultimately type-2 diabetes mellitus (T2DM). The role of endogenous antimicrobial peptides (AMPs), such as the cathelicidin LL-37, in T2DM is unknown. We report here for the first time that patients with T2DM compared to healthy volunteers have elevated plasma levels of LL-37. In a reverse-translational approach, we have investigated the effects of the AMP, peptide 19-2.5, in a murine model of high-fat diet (HFD)-induced insulin-resistance, steatohepatitis and T2DM. HFD-fed mice for 12 weeks caused obesity, an impairment in glycemic regulations, hypercholesterolemia, microalbuminuria and steatohepatitis, all of which were attenuated by Peptide 19-2.5. The liver steatosis caused by feeding mice a HFD resulted in the activation of nuclear factor kappa light chain enhancer of activated B cells (NF-ĸB) (phosphorylation of inhibitor of kappa beta kinase (IKK)α/β, IκBα, translocation of p65 to the nucleus), expression of NF-ĸB-dependent protein inducible nitric oxide synthase (iNOS) and activation of the NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammasome, all of which were reduced by Peptide 19-2.5. Feeding mice, a HFD also resulted in an enhanced expression of the lipid scavenger receptor cluster of differentiation 36 (CD36) secondary to activation of extracellular signal-regulated kinases (ERK)1/2, both of which were abolished by Peptide 19-2.5. Taken together, these results demonstrate that the AMP, Peptide 19-2.5 reduces insulin-resistance, steatohepatitis and proteinuria. These effects are, at least in part, due to prevention of the expression of CD36 and may provide further evidence for a role of metabolic endotoxemia in the pathogenesis of metaflammation and ultimately T2DM. The observed increase in the levels of the endogenous AMP LL-37 in patients with T2DM may serve to limit the severity of the disease., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Mohammad, Al Zoubi, Collotta, Krieg, Wissuwa, Ferreira Alves, Purvis, Norata, Baragetti, Catapano, Solito, Zechendorf, Schürholz, Correa-Vargas, Brandenburg, Coldewey, Collino, Yaqoob, Martin and Thiemermann.)

Background and Aim: Sepsis is an important determinant of the outcome of acute-on-chronic liver failure (ACLF) patients. Omega-3 fatty acids (FAs) are known to suppress inflammation, reduce morbidity, and mortality in postoperative and critically ill patients. We aimed to evaluate the effect of intravenous omega-6 and omega-3 FA lipid emulsions in ACLF patients., Methods: Ninety ACLF patients were randomly allocated to three groups: Gr. A received no lipid emulsions, Gr. B received omega-6 FAs, and Gr. C received omega-3 FAs. The primary and secondary aims were to compare the effects of lipid emulsions on immune modulation, the incidence of bacterial sepsis, and mortality at day 28., Results: The baseline characteristics of the patients were comparable. Serum endotoxin levels remained suppressed by 22% in Gr. C compared with a 4% and 12% rise in Gr. B and A (P < 0.001). Omega-3 FAs also suppressed C-reactive protein levels and neutrophil-to-lymphocyte ratio in Gr. C. Compared with Gr. A, omega-3 FAs reduced sepsis by 86% (HR, 0.14; 95% CI 0.04-0.43; P < 0.001). Omega-3 FAs significantly increased the expression of TLR2 and TLR4 on both CD14 + and CD16 + monocytes, and TLR4, on macrophages and neutrophils. There were no serious adverse events, except transient flushing in 20% and 16.6% of patients receiving omega-6 FAs and omega-3 FAs, respectively., Conclusion: Omega-3 FAs are safe and effective in reducing systemic inflammation, endotoxemia, and sepsis in patients with ACLF. These lipid emulsions could also be considered as effective sources of immunonutrition in such sick patients., (© 2021 Journal of Gastroenterology and Hepatology Foundation and John Wiley & Sons Australia, Ltd.)

Current evidence suggests that high fructose intake results in gut dysbiosis, leading to endotoxemia and NAFLD onset. Thus, the hypothesis of the study was that an enhanced Proteobacteria proportion in the cecal microbiota could be the most prominent trigger of NAFLD through enhanced endotoxin (LPS) in adult high-fructose-fed C57BL/6 mice. Male C57BL/6 mice received a control diet (n = 10, C: 76% of energy as carbohydrates, 0% as fructose) or high-fructose diet (n = 10, HFRU: 76% of energy as carbohydrate, 50% as fructose) for 12 weeks. Outcomes included biochemical analyses, 16S rDNA PCR amplification, hepatic stereology, and RT-qPCR. The groups showed similar body masses during the whole experiment. However, the HFRU group showed greater water intake and blood pressure than the C group. The HFRU group showed a significantly lower amount of Bacteroidetes and a predominant rise in Proteobacteria, implying increased LPS. The HFRU group also showed enhanced de novo lipogenesis (Chrebp expression), while beta-oxidation was decreased (Ppar-alpha expression). These results agree with the deposition of fat droplets within hepatocytes and the enhanced hepatic triacylglycerol concentrations, as observed in the photomicrographs, where the HFRU group had a higher volume density of steatosis than the C group. Thus, we confirmed that a rise in the Proteobacteria phylum proportion was the most prominent alteration in gut-liver axis-induced hepatic steatosis in HFRU-fed C57BL/6 mice. Gut dysbiosis and fatty liver were observed even in the absence of overweight in this dietary adult mouse model., (Copyright © 2021. Published by Elsevier Inc.)

Chronic kidney disease induces disruption of the intestinal epithelial barrier, leading to gut bacterial translocation. Here, we appreciated bacterial translocation by analyzing circulating lipopolysaccharides (LPS) using two methods, one measuring only active free LPS, and the other quantifying total LPS as well as LPS lipid A carbon chain length. This was done in end-stage renal disease (ESRD) patients and healthy volunteers (HV). We observed both higher LPS concentration in healthy volunteers and significant differences in composition of translocated LPS based on lipid A carbon chain length. Lower LPS activity to mass ratio and higher concentration of high-density lipoproteins were found in HV, suggesting a better plasma capacity to neutralize LPS activity. Higher serum concentrations of soluble CD14 and pro-inflammatory cytokines in ESRD patients confirmed this hypothesis. To further explore whether chronic inflammation in ESRD patients could be more related to LPS composition rather than its quantity, we tested the effect of HV and patient sera on cytokine secretion in monocyte cultures. Sera with predominance of 14-carbon chain lipid A-LPS induced higher secretion of pro-inflammatory cytokines than those with predominance of 18-carbon chain lipid A-LPS. TLR4 or LPS antagonists decreased LPS-induced cytokine production by monocytes, demonstrating an LPS-specific effect. Thereby, septic inflammation observed in ESRD patients may be not related to higher bacterial translocation, but to reduced LPS neutralization capacity and differences in translocated LPS subtypes., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Adda-Rezig, Carron, Pais de Barros, Choubley, Charron, Rérole, Laheurte, Louvat, Gaiffe, Simula-Faivre, Deckert, Lagrost, Saas, Ducloux and Bamoulid.)

Objective: Traumatic brain injury (TBI) may lead to the disruption of the intestinal barrier (IB), and to the escape of products of commensal gut bacteria, including lipopolysaccharide (LPS), into the bloodstream. We examined whether lateral fluid percussion injury (LFPI) and post-traumatic epilepsy (PTE) are associated with the increased intestinal permeability and endotoxemia, and whether these events in turn are associated with PTE., Methods: LFPI was delivered to adult male Sprague-Dawley rats. Before, 1 week, and 7 months after LFPI, the IB permeability was examined by measuring plasma concentration of fluorescein isothiocyanate-labeled dextran (FD4) upon its enteral administration. Plasma LPS concentration was measured in the same animals, using enzyme-linked immunosorbent assay. PTE was examined 7 months after LFPI, with use of video-EEG (electroencephalography) monitoring., Results: One week after LFPI, the IB disruption was detected in 14 of 17 and endotoxemia - in 10 of 17 rats, with a strong positive correlation between FD4 and LPS levels, and between plasma levels of each of the analytes and the severity of neuromotor deficit. Seven months after LFPI, IB disruption was detected in 13 of 15 and endotoxemia in 8 of 15 rats, with a strong positive correlation between plasma levels of the two analytes. Five of 15 LFPI rats developed PTE. Plasma levels of both FD4 and LPS were significantly higher in animals with PTE than among the animals without PTE. The analysis of seven rats, which were examined repeatedly at 1 week and at 7 months, confirmed that late IB disruption and endotoxemia were not due to lingering of impairments occurring shortly after LFPI., Significance: LFPI leads to early and remote disruption of IB and a secondary endotoxemia. Early and late perturbations may occur in different subjects. Early changes reflect the severity of acute post-traumatic motor dysfunction, whereas late changes are associated with PTE., (© 2021 International League Against Epilepsy.)

Rationale: Pulmonary endothelial permeability contributes to the high-permeability pulmonary edema that characterizes acute respiratory distress syndrome. Circulating BMP9 (bone morphogenetic protein 9) is emerging as an important regulator of pulmonary vascular homeostasis. Objectives: To determine whether endogenous BMP9 plays a role in preserving pulmonary endothelial integrity and whether loss of endogenous BMP9 occurs during LPS challenge. Methods: A BMP9-neutralizing antibody was administrated to healthy adult mice, and lung vasculature was examined. Potential mechanisms were delineated by transcript analysis in human lung endothelial cells. The impact of BMP9 administration was evaluated in a murine acute lung injury model induced by inhaled LPS. Levels of BMP9 were measured in plasma from patients with sepsis and from endotoxemic mice. Measurements and Main Results: Subacute neutralization of endogenous BMP9 in mice ( N  = 12) resulted in increased lung vascular permeability ( P  = 0.022), interstitial edema ( P  = 0.0047), and neutrophil extravasation ( P  = 0.029) compared with IgG control treatment ( N  = 6). In pulmonary endothelial cells, BMP9 regulated transcriptome pathways implicated in vascular permeability and cell-membrane integrity. Augmentation of BMP9 signaling in mice ( N  = 8) prevented inhaled LPS-induced lung injury ( P  = 0.0027) and edema ( P  < 0.0001). In endotoxemic mice ( N  = 12), endogenous circulating BMP9 concentrations were markedly reduced, the causes of which include a transient reduction in hepatic BMP9 mRNA expression and increased elastase activity in plasma. In human patients with sepsis ( N  = 10), circulating concentratons of BMP9 were also markedly reduced ( P  < 0.0001). Conclusions: Endogenous circulating BMP9 is a pulmonary endothelial-protective factor, downregulated during inflammation. Exogenous BMP9 offers a potential therapy to prevent increased pulmonary endothelial permeability in lung injury.

Endotoxemia is a severe inflammation response induced by infection especially bacterial endotoxin translocation, which severely increases mortality in combination with acute colon injury. Bromodomain-containing protein 4 (BRD4) is an important Bromo and Extra-Terminal (BET) protein to participate in inflammatory responses. However, it is still unknown about the specific connection between BRD4 and inflammation-related pyroptosis in endotoxemia colon. Here, through evaluating the mucous morphology and the expression of tight junction proteins such as occludin and ZO1, we found the upregulation of BRD4 in damaged colon with poor tight junction in an endotoxemia mouse model induced by lipopolysaccharides (LPS). Firstly, the BRD4 inhibitor JQ1 was used to effectively protect colon tight junction in endotoxemia. As detected, high levels of pro-inflammation cytokines IL6, IL1β and IL18 in endotoxemia colon were reversed by JQ1 pretreatment. In addition, JQ1 injection reduced endotoxemia-induced elevation of the phosphorylated NF κB and NLRP3/ASC/caspase 1 inflammasome complex in colon injury. Furthermore, activated pyroptosis markers gasdermins in endotoxemia colon were also blocked by JQ1 pretreatment. Together, our data indicate that BRD4 plays a critical role in regulating pyroptosis-related colon injury induced by LPS, and JQ1 as a BRD4 inhibitors can effectively protect colon from endotoxemia-induced inflammation injury., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Chen, Zhong, Cao, Mao, Li, Yang, Li, Shi, Zhang, Deng, Zu and Liu.)

Sepsis is a major cause of mortality in intensive care units, which results from a severely dysregulated inflammatory response that ultimately leads to organ failure. While antibiotics can help in the early stages, effective strategies to curtail inflammation remain limited. The high mobility group (HMG) proteins are chromosomal proteins with important roles in regulating gene transcription. While HMGB1 has been shown to play a role in sepsis, the role of other family members including HMGXB4 remains unknown. We found that expression of HMGXB4 is strongly induced in response to lipopolysaccharide (LPS)-elicited inflammation in murine peritoneal macrophages. Genetic deletion of Hmgxb4 protected against LPS-induced lung injury and lethality and cecal ligation and puncture (CLP)-induced lethality in mice, and attenuated LPS-induced proinflammatory gene expression in cultured macrophages. By integrating genome-wide transcriptome profiling and a publicly available ChIP-seq dataset, we identified HMGXB4 as a transcriptional activator that regulates the expression of the proinflammatory gene, Nos2 (inducible nitric oxide synthase 2) by binding to its promoter region, leading to NOS2 induction and excessive NO production and tissue damage. Similar to Hmgxb4 ablation in mice, administration of a pharmacological inhibitor of NOS2 robustly decreased LPS-induced pulmonary vascular permeability and lethality in mice. Additionally, we identified the cell adhesion molecule, ICAM1, as a target of HMGXB4 in endothelial cells that facilitates inflammation by promoting monocyte attachment. In summary, our study reveals a critical role of HMGXB4 in exacerbating endotoxemia via transcriptional induction of Nos2 and Icam1 gene expression and thus targeting HMGXB4 may be an effective therapeutic strategy for the treatment of sepsis., Competing Interests: The authors declare no competing interest.

Systemic inflammation plays a crucial role in formation of various pathological conditions, including sepsis, burns, and traumas. The main effector cells participating in progression of systemic inflammation response and sepsis are monocytes, which regulate both innate and acquired immunity via phagocytosis, synthesis of cytokines and chemokines, antigen presentation, and lymphocyte activation. Thus, the monocytes are considered as a link between innate and acquired immunity. The monocyte subpopulations taken into consideration in the study essentially determine the progression of systemic inflammation and could serve as targets for therapeutic intervention. The complexity of the analysis of pathophysiology of systemic inflammation lies in its high variability conditioned by individual peculiarities of the patients and inflammation progression specifications. To overcome these limitation, model of experimental endotoxemia (EE) is used. The results of EE, in turn, cannot be directly extrapolated on patients with the systemic inflammatory response. This review is dedicated to discussing the role of monocyte subpopulations in progression of systemic inflammation/sepsis and EE., Competing Interests: The authors declare that they have no conflicts of interest., (Copyright © 2021 Yaroslav V. Radzyukevich et al.)

Toll-like receptors (TLRs) play critical roles in innate immunity and inflammation. The molecular mechanisms by which TLR signaling is fine-tuned remain to be completely elucidated. Cullin 4B (CUL4B), which assembles the CUL4B-RING E3 ligase complex (CRL4B), has been shown to regulate diverse developmental and physiological processes by catalyzing monoubiquitination for histone modification or polyubiquitination for proteasomal degradation. Here, we identified the role of CUL4B as an intrinsic negative regulator of the TLR-triggered inflammatory response. Deletion of CUL4B in macrophages increased the production of proinflammatory cytokines and decreased anti-inflammatory cytokine IL-10 production in response to pathogens that activate TLR3, TLR4, or TLR2. Myeloid cell-specific Cul4b knockout mice were more susceptible to septic shock when challenged with lipopolysaccharide, polyinosinic-polycytidylic acid or Salmonella typhimurium infection. We further demonstrated that enhanced TLR-induced inflammatory responses in the absence of CUL4B were mediated by increased GSK3β activity. Suppression of GSK3β activity efficiently blocked the TLR-triggered increase in proinflammatory cytokine production and attenuated TLR-triggered death in Cul4b mutant mice. Mechanistically, CUL4B was found to negatively regulate TLR-triggered signaling by epigenetically repressing the transcription of Pten, thus maintaining the anti-inflammatory PI3K-AKT-GSK3β pathway. The upregulation of PTEN caused by CUL4B deletion led to uncontrolled GSK3β activity and excessive inflammatory immune responses. Thus, our findings indicate that CUL4B functions to restrict TLR-triggered inflammatory responses through regulating the AKT-GSK3β pathway.

Sepsis is a dynamic state that progresses at variable rates and has life-threatening consequences. Staging patients along the sepsis timeline requires a thorough knowledge of the evolution of cellular and molecular events at the tissue level. Here, we investigated the kidney, an organ central to the pathophysiology of sepsis. Single-cell RNA-sequencing in a murine endotoxemia model revealed the involvement of various cell populations to be temporally organized and highly orchestrated. Endothelial and stromal cells were the first responders. At later time points, epithelial cells upregulated immune-related pathways while concomitantly downregulating physiological functions such as solute homeostasis. Sixteen hours after endotoxin, there was global cell-cell communication failure and organ shutdown. Despite this apparent organ paralysis, upstream regulatory analysis showed significant activity in pathways involved in healing and recovery. This rigorous spatial and temporal definition of murine endotoxemia will uncover precise biomarkers and targets that can help stage and treat human sepsis., Competing Interests: DJ, JM, TM, AZ, FS, XX, HG, YL, KC, YC, SW, TE, BM, RM, ME, TH, PD No competing interests declared, (© 2021, Janosevic et al.)

Diet-induced metabolic endotoxemia is an important factor in the development of many chronic diseases in animals and man. The gut epithelium is an efficient barrier that prevents the absorption of liposaccharide (LPS). Structural changes to the intestinal epithelium in response to dietary alterations allow LPS to enter the bloodstream, resulting in an increase in the plasma levels of LPS (termed metabolic endotoxemia). LPS activates Toll-like receptor-4 (TLR4) leading to the production of numerous pro-inflammatory cytokines and, hence, low-grade systemic inflammation. Thus, metabolic endotoxemia can lead to several chronic inflammatory conditions. Obesity, diabetes, and non-alcoholic fatty liver disease (NAFLD) can also cause an increase in gut permeability and potential pharmacological and dietary interventions could be used to reduce the chronic low-grade inflammation associated with endotoxemia., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Mohammad and Thiemermann.)

Sepsis is a major cause of mortality in critically ill patients and associated with cardiac dysfunction, a complication linked to immunological and metabolic aberrations. Cardiac neutrophil infiltration and subsequent release of myeloperoxidase (MPO) leads to the formation of the oxidant hypochlorous acid (HOCl) that is able to chemically modify plasmalogens (ether-phospholipids) abundantly present in the heart. This reaction gives rise to the formation of reactive lipid species including aldehydes and chlorinated fatty acids. During the present study, we tested whether endotoxemia increases MPO-dependent lipid oxidation/modification in the mouse heart. In hearts of lipopolysaccharide-injected mice, we observed significantly higher infiltration of MPO-positive cells, increased fatty acid content, and formation of 2-chlorohexadecanal (2-ClHDA), an MPO-derived plasmalogen modification product. Using murine HL-1 cardiomyocytes as in vitro model, we show that exogenously added HOCl attacks the cellular plasmalogen pool and gives rise to the formation of 2-ClHDA. Addition of 2-ClHDA to HL-1 cardiomyocytes resulted in conversion to 2-chlorohexadecanoic acid and 2-chlorohexadecanol, indicating fatty aldehyde dehydrogenase-mediated redox metabolism. However, a recovery of only 40% indicated the formation of non-extractable (protein) adducts. To identify protein targets, we used a clickable alkynyl analog, 2-chlorohexadec-15-yn-1-al (2-ClHDyA). After Huisgen 1,3-dipolar cycloaddition of 5-tetramethylrhodamine azide (N 3 -TAMRA) and two dimensional-gel electrophoresis (2D-GE), we were able to identify 51 proteins that form adducts with 2-ClHDyA. Gene ontology enrichment analyses revealed an overrepresentation of heat shock and chaperone, energy metabolism, and cytoskeletal proteins as major targets. Our observations in a murine endotoxemia model demonstrate formation of HOCl-modified lipids in the heart, while pathway analysis in vitro revealed that the chlorinated aldehyde targets specific protein subsets, which are central to cardiac function.

Fat and sweeteners contribute to obesity. However, it is unknown whether specific bacteria are selectively modified by different caloric and noncaloric sweeteners with or without a high-fat diet (HFD). Here, we combined extensive host phenotyping and shotgun metagenomics of the gut microbiota to investigate this question. We found that the type of sweetener and its combination with an HFD selectively modified the gut microbiota. Sucralose and steviol glycosides led to the lowest α-diversity of the gut microbiota. Sucralose increased the abundance of B. fragilis in particular, resulting in a decrease in the abundance of occludin and an increase in proinflammatory cytokines, glucose intolerance, fatty acid oxidation and ketone bodies. Sucrose+HFD showed the highest metabolic endotoxemia, weight gain, body fat, total short chain fatty acids (SCFAs), serum TNFα concentration and glucose intolerance. Consumption of sucralose or sucrose resulted in enrichment of the bacterial genes involved in the synthesis of LPS and SCFAs. Notably, brown sugar and honey were associated with the absence of metabolic endotoxemia, increases in bacterial gene diversity and anti-inflammatory markers such as IL-10 and sIgA, the maintenance of glucose tolerance and energy expenditure, similar to the control group, despite the consumption of an HFD. These findings indicate that the type of sweetener and an HFD selectively modify the gut microbiota, bacterial gene enrichment of metabolic pathways involved in LPS and SCFA synthesis, and metabolic endotoxemia associated with different metabolic profiles.

The responses of gut microbiota to dietary proteins have been studied previously. However, the effects of dietary proteins supplemented with a high-fat diet (HFD) on the metabolite biomarkers associated with non-alcoholic fatty liver disease (NAFLD) are not well understood. To understand the underlying mechanisms, C57BL/6J mice were fed with either a low-fat diet with casein (LFC) or an HFD with casein (HFC), fish (HFF), or mutton proteins (HFM), and their cecal microbiota and liver metabolites were analyzed. At the phylum level, the HFD group had a relatively higher abundance of Firmicutes compared to the LFC-diet group. At the genus level, the HFF-diet group had the highest abundance of Lactobacillus and Akkermansia compared to the HFC- and HFM-diet groups. Furthermore, mice fed with the HFF diet had significantly reduced levels of hepatic metabolites involved in oxidative stress and bile acid metabolism. Thus, meat proteins in HFD interact in the host to create distinct responses in the gut microbiota and its metabolites.

In this systematic review, we critically evaluated human clinical trials that assessed the effects of dietary fat quality on metabolic endotoxaemia. The studies were selected from three databases (PubMed, Scopus and Cochrane Library), and the keywords were defined according to the Medical Subject Headings indexing terminology. Two authors searched independently, according to the pre-defined selection criteria. Quality and risk assessment of bias for each selected study were also evaluated. The results of the included studies demonstrated associations between higher SFA intake and increased postprandial lipopolysaccharide (LPS) concentrations. On the other hand, after the consumption of PUFA, bloodstream LPS concentrations were lower. However, in none of the long-term studies, the consumption of dietary fats did not seem to exert effects on LPS concentration. Hence, SFA seem to act as a risk factor for transient increase in endotoxaemia, while PUFA demonstrated exerting a protective effect. Taken together, the evidence suggests that the dietary fatty acid profile may influence bloodstream endotoxin concentrations through modulation of factors such LPS clearance, alkaline phosphatase activity, bile acid metabolism, intestinal permeability and intestinal microbiota composition.

Background: Gut microbial imbalance may contribute to endotoxemia, inflammation, and oxidative stress in heart failure (HF). Changes occurring in the intestinal microbiota and inflammatory/oxidative milieu during HF progression and following left ventricular assist device (LVAD) or heart transplantation (HT) are unknown. We aimed to investigate variation in gut microbiota and circulating biomarkers of endotoxemia, inflammation, and oxidative stress in patients with HF (New York Heart Association, Class I-IV), LVAD, and HT., Methods: We enrolled 452 patients. Biomarkers of endotoxemia (lipopolysaccharide and soluble [sCD14]), inflammation (C-reactive protein, interleukin-6, tumor necrosis factor-α, and endothelin-1 adiponectin), and oxidative stress (isoprostane) were measured in 644 blood samples. A total of 304 stool samples were analyzed using 16S rRNA sequencing., Results: Gut microbial community measures of alpha diversity were progressively lower across worsening HF class and were similarly reduced in patients with LVAD and HT (p < 0.05). Inflammation and oxidative stress were elevated in patients with Class IV HF vs all other groups (all p < 0.05). Lipopolysaccharide was elevated in patients with Class IV HF (vs Class I-III) as well as in patients with LVAD and HT (p < 0.05). sCD14 was elevated in patients with Class IV HF and LVAD (vs Class I-III, p < 0.05) but not in patients with HT., Conclusions: Reduced gut microbial diversity and increased endotoxemia, inflammation, and oxidative stress are present in patients with Class IV HF. Inflammation and oxidative stress are lower among patients with LVAD and HT relative to patients with Class IV HF, whereas reduced gut diversity and endotoxemia persist in LVAD and HT., (Copyright © 2020 International Society for Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.)

Scope: This study takes a novel approach to investigate the anti-inflammatory and antioxidant effects of prebiotic oat beta-glucan (OAT) and the probiotic Lactobacillus rhamnosus GG (LGG) against high-fat diets (HFD) by examining the fatty acid profiles in the gut-liver-brain axis., Method and Results: HFD-fed C57BL/6N mice are supplemented with OAT and/or LGG for 17 weeks. Thereafter, mass spectrometry-based targeted lipidomics is employed to quantify short-chain fatty acids (SCFA), polyunsaturated fatty acids (PUFA), and oxidized PUFA products in the tissues. Acetate levels are suppressed by HFD in all tissues but reversed in the brain and liver by supplementation with LGG, OAT, or LGG + OAT, and in cecum content by LGG. The n-6/n-3 polyunsaturated fatty acid (PUFA) ratio is elevated by HFD in all tissues but is lowered by LGG and OAT in the cecum and the brain, and by LGG + OAT in the brain, suggesting the anti-inflammatory property of LGG and OAT. LGG and OAT synergistically, but not individually attenuate the increase in non-enzymatic oxidized products, indicating their synbiotic antioxidant property., Conclusion: The regulation of the fatty acid profiles by LGG and OAT, although incomplete, but demonstrates their anti-inflammatory and antioxidant potentials in the gut-liver-brain axis against HFD., (© 2020 Wiley-VCH GmbH.)

K ATP channels in the vasculature composed of Kir6.1 regulate vascular tone and may contribute to the pathogenesis of endotoxemia. We used mice with cell-specific deletion of Kir6.1 in smooth muscle (smKO) and endothelium (eKO) to investigate this question. We found that smKO mice had a significant survival disadvantage compared with their littermate controls when treated with a sub-lethal dose of lipopolysaccharide (LPS). All cohorts of mice became hypotensive following bacterial LPS administration; however, mean arterial pressure in WT mice recovered to normal levels, whereas smKO struggled to overcome LPS-induced hypotension. In vivo and ex vivo investigations revealed pronounced cardiac dysfunction in LPS-treated smKO, but not in eKO mice. Similar results were observed in a cecal slurry injection model. Metabolomic profiling of hearts revealed significantly reduced levels of metabolites involved in redox/energetics, TCA cycle, lipid/fatty acid and amino acid metabolism. Vascular smooth muscle-localised K ATP channels have a critical role in the response to systemic infection by normalising cardiac function and haemodynamics through metabolic homeostasis. KEY MESSAGES: • Mice lacking vascular K ATP channels are more susceptible to death from infection. • Absence of smooth muscle K ATP channels depresses cardiac function during infection. • Cardiac dysfunction is accompanied by profound changes in cellular metabolites. • Findings from this study suggest a protective role for vascular K ATP channels in response to systemic infection.

Intracellular adenosine monophosphate (AMP) is indispensable for cellular metabolic processes, and it is interconverted to ADP and/or ATP or activates AMP-activated protein kinase (AMPK). However, the specific biological function of extracellular AMP has not been identified. We evaluated the effect of extracellular AMP using in vivo and in vitro models of endotoxemia. We found that AMP inhibited inflammation and neutrophil activation in lipopolysaccharide (LPS)-induced endotoxemic mice. The effects of extracellular AMP were abolished by an adenosine 1 receptor (A1R) antagonist but were not influenced by inhibiting the conversion of AMP to adenosine (ADO), indicating that AMP inhibited inflammation by directly activating A1R. In addition, in vitro experiments using LPS-stimulated mouse neutrophils showed that AMP inhibited LPS-induced reactive oxygen species (ROS) production, degranulation, and cytokine production, while the effects were reversed by an A1R antagonist. Further research showed that AMP regulated LPS-stimulated neutrophil functions by inhibiting the p38 MAPK pathway. These findings were also confirmed in primary neutrophils derived from healthy human blood. Moreover, we collected serum samples from septic patients. We found that AMP levels were increased compared with those of healthy volunteers and that AMP levels were negatively correlated with disease severity. Together, these data provide evidence that extracellular AMP acts on A1R to suppress endotoxemia-induced inflammation by inhibiting neutrophil overactivation and that the p38 MAPK signaling pathway is involved., (Copyright © 2020 Hua, Liu, Zhang, Wang, Wei and Qin.)

There is evidence for the effects of platelet inhibition on innate immune activation. Circulating microRNAs (miRNAs) have been implicated as markers of platelet and leukocyte activation. In the present study, we assessed the effects of P2Y 12 inhibitors on platelet and leukocyte miRNAs during endotoxemia. Healthy volunteers were randomly assigned to receive oral ticagrelor ( n = 10), clopidogrel ( n = 8) or no drug ( n = 8) for one week, followed by an intravenous bolus of 2 ng/kg endotoxin. Serum was collected at baseline, after one week of antiplatelet treatment and 6 and 24 h after endotoxin administration. MiRNAs were screened using LNA-based qPCR, followed by TaqMan-qPCR validation of candidates. Clinical validation was performed in 41 sepsis patients. Platelet-enriched miR-197, miR-223 and miR-223* were decreased in volunteers following antiplatelet therapy. Endotoxin increased platelet miRNAs, whilst the opposite effect was seen for leukocyte-enriched miR-150. Neither of these endotoxin-mediated effects were altered by P2Y 12 inhibitors. Sepsis patients with fatal outcomes ( n = 12) had reduced miR-150 levels compared with survivors ( n = 29). In conclusion, we show that miR-150 is downregulated in experimental endotoxemia and can predict survival in sepsis but is unaffected by P2Y 12 inhibition. While P2Y 12 inhibition reduces platelet-associated miRNAs in healthy volunteers, it fails to attenuate the response of platelet miRNAs to endotoxemia.

High-fat diet increase two to three times the plasma lipopolysaccharide (LPS) levels and induce subclinical inflammation. Diet can modify gene expression due to epigenetic processes related to MicroRNAs (miRNAs). MicroRNAs (miRNAs) play important role in the post-transcriptional mechanisms involved in regulation of expression of genes related to the inflammatory response. Also, diet can indirectly induce post-transcriptional regulation of gene expression by miRNAs, which may affect the risk for the development of chronic diseases., Objective: This study investigated the effect of high-fat high-saturated meal ingestion on plasma miRNA expression and LPS levels during the postprandial period in healthy women., Methods: An interventional study was carried out in which a high-fat breakfast (1067.45 kcal), composed mainly of saturated fatty acids (56 g), and 500 mL of water, was offered. Blood samples were collected at baseline and 1, 3 and 5 h after meal intake. The studied population consisted of healthy women (n = 11), aged between 20 and 40 years, and body mass index (BMI) between 18.5 and 25 kg/m 2 . Plasma levels of lipid profile, cytokines, adhesion molecules, and LPS were measured at the 3 time points. A profile of 752 human plasma miRNA expression was analyzed by real-time PCR assay. These analyzes were performed for all blood collection time-points., Results: Expression profile analysis revealed 33 differentially expressed plasma circulating miRNAs compared to that of the control group. MiR-145-5p and miR-200 were differentially modulated in all time-points post meal consumption. In addition, there was a significant increase in plasma LPS, triglycerides, myristic and palmitic saturated fatty acids levels at the 3 time-points in comparison with the control basal levels. We also observed increased levels of the plasma tumor necrosis factor alpha (TNF-α) cytokine and the vascular cell adhesion molecule 1 (VCAM-1) levels after 5 h post meal ingestion., Conclusion: Ingestion of high-fat high-saturated meal was able to induce metabolic endotoxemia and increase the expression of pro-inflammatory molecules such as TNF-alpha and VCAM-1, as well as modulating circulating miRNAs possibly controlling inflammatory and lipid metabolism proteins at the postprandial period., (Copyright © 2019 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.)

Societal lifestyle changes, especially increased consumption of a high-fat diet lacking dietary fibers, lead to gut microbiota dysbiosis and enhance the incidence of adiposity and chronic inflammatory disease. We aimed to investigate the metabolic effects of inulin with different degrees of polymerization on high-fat diet-fed C57BL/6 J mice and to evaluate whether different health outcomes are related to regulation of the gut microbiota. Short-chain and long-chain inulins exert beneficial effects through alleviating endotoxemia and inflammation. Antiinflammation was associated with a proportional increase in short-chain fatty acid-producing bacteria and an increase in the concentration of short-chain fatty acids. Inulin might decrease endotoxemia by increasing the proportion of Bifidobacterium and Lactobacillus, and their inhibition of endotoxin secretion may also contribute to antiinflammation. Interestingly, the beneficial health effects of long-chain inulin were more pronounced than those of short-chain inulin. Long-chain inulin was more dependent than short-chain inulin on species capable of processing complex polysaccharides, such as Bacteroides. A good understanding of inulin-gut microbiota-host interactions helps to provide a dietary strategy that could target and prevent high-fat diet-induced endotoxemia and inflammation through a prebiotic effect.

Macrophage plasticity is a process that allows macrophages to switch between two opposing phenotypes based on differential stimuli. Interferon γ (IFNγ)-primed macrophages stimulated with lipopolysaccharide (LPS) [M(IFNγ+LPS)] produce high levels of pro-inflammatory cytokines such as IL-12, TNFα, and IL-6 and low levels of the anti-inflammatory cytokine IL-10, while those stimulated with LPS in the presence of the immune complex (IC) [M(IFNγ+LPS+IC)] produce high levels of IL-10 and low levels of IL-12. In this study, we investigated the plasticity between M(IFNγ+LPS) and M(IFNγ+LPS+IC) in vitro and compared one of the active histone marks [histone H3 lysine 4 trimethylation (H3K4me3)] between M(IFNγ+LPS) and M(IFNγ+LPS+IC) using murine bone marrow-derived macrophages. We found that in an in vitro system, macrophages exhibited functional plasticity from M(LPS) to M(LPS+IC) upon repolarization after 2 days of washout period while IFNγ priming before LPS stimulation prevented this repolarization. Phosphorylation of p38, SAPK/JNK, and NF-κB p65 in M(LPS+IC) repolarized from M(LPS) was similar to that in M(LPS+IC) polarized from resting macrophages. To obtain the epigenetic profiles of M(IFNγ+LPS) and M(IFNγ+LPS+IC), the global enrichment of H3K4me3 was evaluated. M(IFNγ+LPS) and M(IFNγ+LPS+IC) displayed marked differences in genome-wide enrichment of H3K4me3. M(IFNγ+LPS+IC) showed increased global enrichment of H3K4me3, whereas M(IFNγ+LPS) showed decreased enrichment when compared to unstimulated macrophages. Furthermore, M(IFNγ+LPS+IC) exhibited high levels of H3K4me3 enrichment in all cis -regulatory elements. At the individual gene level, the results showed increased H3K4me3 enrichment in the promoters of known genes associated with M(IFNγ+LPS+IC), including Il10, Cxcl1, Csf3 , and Il33 , when compared with those of M(IFNγ+LPS). Finally, we investigated the impact of M(IFNγ+LPS+IC) on the systemic immune response by adoptive transfer of M(IFNγ+LPS+IC) in an LPS-induced endotoxemia model. The cytokine profile revealed that mice with adoptively transferred M(IFNγ+LPS+IC) had acutely reduced serum levels of the inflammatory cytokines IL-1β and IL-p12p70. This study highlights the importance of epigenetics in regulating macrophage activation and the functions of M(IFNγ+LPS+IC) that may influence macrophage plasticity and the potential therapeutic use of macrophage transfer in vivo ., (Copyright © 2020 Ruenjaiman, Butta, Leu, Pongpanich, Leelahavanichkul, Kueanjinda and Palaga.)

Sepsis is a complex syndrome resulting from a dysregulated immune response to an infection. Due to the high prevalence, morbidity, and mortality, there is a lot of interest in understanding pathways that play a role in sepsis, with a focus on the immune system. Tumor necrosis factor (TNF) is a pleiotropic pro-inflammatory cytokine and a master regulator of the immune system but clinical trials with TNF blockers in sepsis have failed to demonstrate significant protection. Since TNF stimulates two different receptors, TNF receptor 1 (TNFR1) and TNFR2, pan-TNF inhibition might be suboptimal since both receptors have opposite functions in polymicrobial sepsis. Therefore, we hypothesized that TNF has a dual role in sepsis, namely a mediating and a protective role, and that protection might be obtained by TNFR1-specific inhibition. We here confirmed that TNFR1 -/- mice are protected in the sterile endotoxemia model, whereas TNFR1 deficiency did not protect in the cecal ligation and puncture (CLP)-induced polymicrobial sepsis model. Since whole body TNFR1 blockage might be deleterious because of the antibacterial function of TNF/TNFR1 signaling, we focused on the potential devastating role of TNF/TNFR1 signaling in specific cell types. We were interested in the gut epithelium, the endothelium, and hepatocytes using conditional TNFR1 -/- mice, as these cell types have been shown to play a role in sepsis. However, none of these conditional knockout mice showed improved survival in the CLP model. We conclude that cell-specific targeting of TNFR1 to these cell types has no therapeutic future in septic peritonitis., (Copyright © 2019 Vandewalle, Steeland, Van Ryckeghem, Eggermont, Van Wonterghem, Vandenbroucke and Libert.)

Metabolic endotoxemia is a condition in which blood lipopolysaccharide (LPS) levels are elevated, regardless of the presence of obvious infection. It has been suggested to lead to chronic inflammation-related diseases such as obesity, type 2 diabetes mellitus, non-alcoholic fatty liver disease (NAFLD), pancreatitis, amyotrophic lateral sclerosis, and Alzheimer's disease. In addition, it has attracted attention as a target for the prevention and treatment of these chronic diseases. As metabolic endotoxemia was first reported in mice that were fed a high-fat diet, research regarding its relationship with diets has been actively conducted in humans and animals. In this review, we summarize the relationship between fat intake and induction of metabolic endotoxemia, focusing on gut dysbiosis and the influx, kinetics, and metabolism of LPS. We also summarize the recent findings about dietary factors that attenuate metabolic endotoxemia, focusing on the regulation of gut microbiota. We hope that in the future, control of metabolic endotoxemia using dietary factors will help maintain human health.

In patients with active lupus, spontaneous endotoxemia and possibly tolerance to lipopolysaccharide (LPS) is a potentially adverse complication. Similarly, previous reports have demonstrated that FcGRIIb deficient mice (FcGRIIb-/-; a lupus mouse model) are susceptible to LPS tolerance-induced decreased cytokine responses that inadequate for the organismal control. Thus, understanding the relationship between FcGRIIb and LPS tolerance could improve the therapeutic strategy for lupus. LPS tolerance can be induced through sequential LPS stimulations in either cells or a model organism. In RAW264.7 (a mouse macrophage cell-line), sequential LPS stimulation induced the secretion of Lipocalin-2 (Lcn-2) despite reduced cytokine secretion and severe energy depletion, as measured by the extracellular flux analysis, typical of LPS tolerance. In contrast, treatment with recombinant Lcn-2 (rLcn-2) attenuated LPS tolerance, as shown by an increase in secreted cytokines and altered macrophage polarization toward M1 (increased iNOS and TNF-α ) in RAW264.7 cells. These results suggest a role of Lcn-2 in LPS tolerance attenuation. In bone marrow derived macrophages, Lcn-2 level was similar in LPS tolerant FcGRIIb-/- and wild-type (WT) cells despite the increased LPS tolerance of FcGRIIb-/- cells, suggesting relatively low basal levels of Lcn-2 produced in FcGRIIb-/- cells. In addition, attenuation of LPS tolerance effectuated by granulocyte-monocyte colony stimulating factor (GM-CSF) reduced Lcn-2 in both cell types, implying an inverse correlation between Lcn-2 and the severity of LPS tolerance. Consequently, rLcn-2 improved LPS tolerance only in FcGRIIb-/- macrophages and attenuated disease severity of cecal ligation and puncture (CLP) sepsis pre-conditioning with sequential LPS injection (LPS-CLP model) only in FcGRIIb-/- mice, but not in WT mice. To summarize, inadequate Lcn-2 production in FcGRIIb-/- macrophage might, at least in part, be responsible for the inordinate LPS tolerance compared with WT cells. Additionally, supplementation of rLcn-2 attenuates LPS tolerance in FcGRIIb-/- macrophages in vitro, and in FcGRIIb-/- mice with LPS-CLP sepsis in vivo. In conclusion, Lcn-2 secreted by macrophages is possibly an autocrine signal to counter the reduced cytokine secretion in LPS tolerance.

Sepsis is defined as life-threatening organ dysfunction caused by the dysregulated host response to infection. Despite serious mortality and morbidity, no sepsis-specific drugs exist. Endotoxemia is often used to model the hyperinflammation associated with early sepsis. This model classically uses lipopolysaccharide (LPS) from Gram-negative pathogens to activate the immune system, leading to hyperinflammation, microcirculatory disturbances and death. Other toxins may also be used to activate the immune system including Gram-positive peptidoglycan (PG) and lipoteichoic acid (LTA). In addition to these standard toxins, other bacterial components can induce inflammation. These molecules activate different signaling pathways and produce different physiological responses which can be taken advantage of for sepsis modeling. Endotoxemia modeling can provide information on pathways to inflammation in sepsis and contribute to preclinical drug development.

The gastrointestinal (GI) tract can play a critical role in the development of pathologies associated with overeating, overweight and obesity. We previously observed that supplementation with anthocyanins (AC) (particularly glycosides of cyanidin and delphinidin) mitigated high fat diet (HFD)-induced development of obesity, dyslipidemia, insulin resistance and steatosis in C57BL/6J mice. This paper investigated whether these beneficial effects could be related to AC capacity to sustain intestinal monolayer integrity, prevent endotoxemia, and HFD-associated dysbiosis. The involvement of redox-related mechanisms were further investigated in Caco-2 cell monolayers. Consumption of a HFD for 14 weeks caused intestinal permeabilization and endotoxemia, which were associated with a decreased ileum expression of tight junction (TJ) proteins (occludin, ZO-1 and claudin-1), increased expression of NADPH oxidase (NOX1 and NOX4) and NOS2 and oxidative stress, and activation of redox sensitive signals (NF-κB and ERK1/2) that regulate TJ dynamics. AC supplementation mitigated all these events and increased GLP-2 levels, the intestinal hormone that upregulates TJ protein expression. AC also prevented, in vitro, tumor necrosis factor alpha-induced Caco-2 monolayer permeabilization, NOX1/4 upregulation, oxidative stress, and NF-κB and ERK activation. HFD-induced obesity in mice caused dysbiosis and affected the levels and secretion of MUC2, a mucin that participates in intestinal cell barrier protection and immune response. AC supplementation restored microbiota composition and MUC2 levels and distribution in HFD-fed mice. Thus, AC, particularly delphinidin and cyanidin, can preserve GI physiology in HFD-induced obesity in part through redox-regulated mechanisms. This can in part explain AC capacity to mitigate pathologies, i.e. insulin resistance and steatosis, associated with HFD-associated obesity., (Copyright © 2019 The Authors. Published by Elsevier B.V. All rights reserved.)

Alpha-1-acid glycoprotein (AGP-1) is a major positive acute phase glycoprotein with unknown functions that likely play a role in inflammation. We tested its involvement in a variety of inflammatory responses using human AGP-1 purified to apparent homogeneity and confirmed its identity by immunoblotting and mass spectrometry. AGP-1 alone upregulated MAPK signaling in murine peritoneal macrophages. However, when given in combination with TLR ligands, AGP-1 selectively augmented MAPK activation induced by ligands of TLR-2 (Braun lipoprotein) but not TLR-4 (lipopolysaccharide). In vivo treatment of AGP-1 in a murine model of sepsis with or without TLR-2 or TLR-4 ligands, selectively potentiated TLR-2-mediated mortality, but was without significant effect on TLR-4-mediated mortality. Furthermore, in vitro, AGP-1 selectively potentiated TLR-2 mediated adhesion of human primary immune cell, neutrophils. Hence, our studies highlight a new role for the acute phase protein AGP-1 in sepsis via its interaction with TLR-2 signaling mechanisms to selectively promote responsiveness to one of the two major gram-negative endotoxins, contributing to the complicated pathobiology of sepsis., (Copyright © 2019 Elsevier GmbH. All rights reserved.)

The aim of the present study was to examine whether the immune-modulatory bacteria Lactobacillus fermentum CECT5716 (LC40) ameliorates disease activity and cardiovascular complications in a female mouse model of lupus. Eighteen-week-old NZBWF1 [systemic lupus erythematosus (SLE)] and NZW/LacJ (control) mice were treated with vehicle or LC40 (5 × 10 8 colony-forming units/d) for 15 wk. LC40 treatment reduced lupus disease activity, blood pressure, cardiac and renal hypertrophy, and splenomegaly in SLE mice. LC40 reduced the elevated T, B, regulatory T cells (T reg ), and T helper (T h )-1 cells in mesenteric lymph nodes of lupus mice. LC40 lowered the higher plasma concentration of proinflammatory cytokines observed in lupus mice. Aortas from SLE mice showed reduced endothelium-dependent vasodilator responses to acetylcholine. Endothelial dysfunction found in SLE is related to an increase of both NADPH oxidase-driven superoxide production and eNOS phosphorylation at the inhibitory Thr 495 . These activities returned to normal values after a treatment with LC40. Probiotic administration to SLE mice reduced plasma LPS levels, which might be related to an improvement of the gut barrier integrity. LC40 treatment increases the Bifidobacterium count in gut microbiota of SLE mice. In conclusion, our findings identify the gut microbiota manipulation with LC40 as an alternative approach to the prevention of SLE and its associated vascular damage.-Toral, M., Robles-Vera, I., Romero, M., de la Visitación, N., Sánchez, M., O'Valle, F., Rodriguez-Nogales, A., Gálvez, J., Duarte, J., Jiménez, R. Lactobacillus fermentum CECT5716: a novel alternative for the prevention of vascular disorders in a mouse model of systemic lupus erythematosus.

The prevalence of metabolic syndrome (MetSyn) has risen 35% since 2012 and over two-thirds of Americans exhibit features characterizing this condition (obesity, dyslipidemia, hyperglycemia, insulin resistance and/or endothelial dysfunction). The aim of this study was to evaluate the effects of a novel dietary supplemental organic mineral complex (OMC) on these risk factors in a rodent model of MetSyn. Six-week old male Sprague-Dawley rats were fed either standard chow or a high-fat diet (HFD) composed of 60% kcal from fat for 10 weeks. Rats were also treated with OMC in their drinking water at either 0 mg/mL (control), 0.6 mg/mL, or 3.0 mg/mL. The HFD-treated rats exhibited significantly increased body mass (p<0.05), epididymal fat pad mass (p<0.001), waist circumference (p = 0.010), in addition to elevations in plasma endotoxins (p<0.001), ALT activity (p<0.001), fasting serum glucose (p = 0.025) and insulin concentrations (p = 0.009). OMC did not affect body weight or adiposity induced by the HFD. At the higher dose OMC significantly blunted HFD-induced hyperglycemia (p = 0.021), whereas both low and high doses of OMC prevented HFD-induced endotoxemia (p = 0.002 and <0.001, respectively) and hepatocyte injury (ALT activity, p<0.01). Despite evidence of oxidative stress (elevated urinary H2O2 p = 0.032) in HFD-fed rats, OMC exhibited no demonstrable antioxidative effect. Consistent with prior studies, mesenteric arteries from HFD rats had more uncoupled eNOS (p = 0.006) and iNOS protein expression (p = 0.027) in addition to impaired endothelium-dependent vasodilation that was abrogated by the high dose of OMC (p<0.05). This effect of OMC may be attributed to the high nitrate content of the supplement. These findings suggest that the OMC supplement, particularly at the higher dose, ameliorated several risk factors associated with MetSyn via a non-antioxidant-dependent mechanism., Competing Interests: EG is currently Director of Research and Science at Isagenix International, LLC, the sponsor of the study and a marketer of dietary supplements containing OMC. Isagenix International, LLC funded this study and provided salary support for the Graduate Research Assistant (MSC). There are no patents, products in development, or marketed products to declare. This does not alter our adherence to all PLOS ONE policies on sharing data and materials. All other authors report no conflicts of interest.