Low-grade endotoxemia is associated with cardiovascular events in community-acquired pneumonia

OBJECTIVES

Community-acquired pneumonia (CAP) is associated with low-grade endotoxemia but its relationship with cardiovascular events (CVE) has not been investigated.

METHODS

We evaluated the incidence of CVE including myocardial infarction, stroke, and cardiovascular death in 523 adult patients hospitalized for CAP. Serum lipopolysaccharide (LPS) and zonulin, a marker of gut permeability, were analyzed in the cohort, that was followed-up during hospitalization and up to 43 months thereafter.

RESULTS

During the hospital-stay, 55 patients experienced CVE with a progressive increase from the lowest (0.6%) to highest LPS tertile (23.6%, p < 0.001). Logistic regression analyses showed that higher LPS tertile was independently associated with CVE; LPS significantly correlated with age, hs-CRP and zonulin. In a sub-group of 23 CAP patients, blood E. coli DNA was higher in patients compared to 24 controls and correlated with LPS. During the long-term follow-up, 102 new CVE were registered; the highest tertile of LPS levels was associated with incident CVE; Cox regression analysis showed that LPS tertiles, age, history of CHD, and diabetes independently predicted CVE.

CONCLUSIONS

In CAP low-grade endotoxemia is associated to short- and long-term risk of CVE. Further study is necessary to assess if lowering LPS by non-absorbable antibiotics may result in improved outcomes.

Low-grade endotoxemia in acute pulmonary embolism: Links with prothrombotic plasma fibrin clot phenotype

BACKGROUND

Lipopolysaccharide (LPS) can traverse the intestinal barrier and enter bloodstream, causing endotoxemia and triggering inflammation. Increased circulating LPS was reported in arterial thromboembolism. We investigated whether increased LPS levels occur in acute pulmonary embolism (PE) and if it is associated with a prothrombotic state.

METHODS

We studied 120 normotensive PE patients (aged 59 [48-68] years) on admission, after 5-7 days, and after a 3-month anticoagulation. Serum LPS levels, along with zonulin, a marker of gut permeability, endogenous thrombin potential (ETP), fibrin clot permeability (Ks), clot lysis time (CLT), fibrinolysis proteins, and platelet markers were assessed.

RESULTS

Median LPS concentration on admission was 70.5 (61.5-82) pg/mL (min-max, 34-134 pg/mL), in association with C-reactive protein (r = 0.22, p = 0.018), but not with fibrinogen, D-dimer or platelet markers. Patients with more severe PE had higher LPS levels compared with the remainder. Median zonulin level was 3.26 (2.74-4.08) ng/mL and correlated with LPS (r = 0.66, p < 0.0001). Patients with baseline LPS levels in the top quartile (≥82 pg/mL; n = 29) compared to lower quartiles had 18.6 % increased ETP, 14.5 % reduced Ks, and 25.3 % prolonged CLT, related to higher plasminogen activator inhibitor type 1 (PAI-1) levels. LPS decreased by 23.4 % after 5-7 days and by 40.4 % after 3-month anticoagulation together with reduced zonulin by 18.4 % and 22.3 %, respectively, compared to baseline (all p < 0.001). LPS levels were not related with fibrin characteristics and other variables assessed at 3 months.

CONCLUSIONS

Low-grade endotoxemia is detectable in patients with acute PE and may contribute to increased thrombin generation and PAI-1-mediated hypofibrinolysis.

Gut dysbiosis-related thrombosis in inflammatory bowel disease: Potential disease mechanisms and emerging therapeutic strategies

Patients with inflammatory bowel disease (IBD) have an increased risk of developing venous thromboembolic events, which have a considerable impact on morbidity and mortality. Chronic inflammation plays a crucial role in the pathogenesis of thrombotic events in patients with IBD. However, many unresolved questions remain, particularly regarding the mechanisms that determine the persistent inflammatory state independent of disease activity. This review explored the role of gut microbiota dysbiosis and intestinal barrier dysfunction, which are considered distinctive features of IBD, in determining pro-thrombotic tendencies. Gut-derived endotoxemia due to the translocation of bacterial lipopolysaccharides (LPS) from the intestine to the bloodstream and the bacterial metabolite trimethylamine-N-oxide (TMAO) are the most important molecules involved in gut dysbiosis-related thrombosis. The pathogenic prothrombotic pathways linked to LPS and TMAO have been discussed. Finally, we present emerging therapeutic approaches that can help reduce LPS-mediated endotoxemia and TMAO, such as restoring intestinal eubiosis, normalizing intestinal barrier function, and counterbalancing the effects of LPS and TMAO.

Retinoic acid ameliorates low-grade endotoxemia-induced mastitis by limiting inflammatory responses in mice

Mastitis is a serious disease for humans and animals, which causes huge economic losses in the dairy industry and is hard to prevent due to the complex and unclear pathogenesis. Subacute ruminal acidosis (SARA) has contributed to the development of mastitis by inducing ruminal dysbiosis and subsequent low-grade endotoxemia (LGE), however, how ruminal metabolic changes regulate this progress is still unclear. Our previous study revealed that cows with SARA had increased ruminal retinoic acid (RA) levels, a metabolic intermediate of vitamin A that plays an essential role in mucosal immune responses. Hence, the aim of this study was to investigate the protective effect of RA on LGE-induced mastitis and the underlying mechanisms in mice. The results showed that RA alleviated LGE-induced mastitis, as evidenced by RA significantly reduced the increase in mammary proinflammatory cytokines and improved blood-milk barrier injury caused by LGE. In addition, RA increased the expression of tight junction proteins, including ZO-1, occludin and claudin-3. Furthermore, we found that RA limited the mammary inflammatory responses by inhibiting the activation of NF-κB and NLRP3 signaling pathways. These findings suggest that RA effectively alleviates LGE-induced mastitis and implies a potential strategy for the treatment and prevention of mastitis and other diseases.

Role of brain-derived neurotrophic factor in endotoxaemia-induced acute lung injury

Acute lung injury (ALI) or acute respiratory distress syndrome (ARDS), which is a pulmonary manifestation of a systemic reactive inflammatory syndrome, is a serious disease with high mortality, and sepsis is an important risk factor in the development of ALI. Brain-derived neurotrophic factor (BDNF) is a member of the nerve growth factor family. It plays an essential role in the regulation of the modification of synaptic efficacy and brain metabolic activity and enhances neuronal survival. However, the role and underlying mechanism of BDNF in sepsis-induced ALI remain unclear. Here, we sought to observe the expression of BDNF in the lung tissues of mice. C57BL/6J mice were divided randomly into two groups: saline (n = 4) and lipopolysaccharide (LPS) (n = 4). We found that BDNF expression was elevated in the lung tissues of septic mice. Furthermore, we found that BDNF colocalized with aquaporin 5, a marker for type I alveolar epithelial cells, by immunofluorescence staining. In addition, we also found that tropomyosin-related kinase B, the specific receptor of BDNF, colocalized with surfactant protein C, a marker for type II alveolar epithelial cells, by immunofluorescence staining. Finally, the present study indicated that BDNF may alleviate excessive LPS-induced autophagy in alveolar epithelial cells. Overall, we hypothesize that BDNF expression increases in the lung tissues of septic mice as a compensatory mechanism to ameliorate sepsis-induced ALI by inhibiting excessive alveolar epithelial cell autophagy.

Oxidative Mechanisms and Cardiovascular Abnormalities of Cirrhosis and Portal Hypertension

In patients with portal hypertension, there are many complications including cardiovascular abnormalities, hepatorenal syndrome, ascites, variceal bleeding, and hepatic encephalopathy. The underlying mechanisms are not yet completely clarified. It is well known that portal hypertension causes mesenteric congestion which produces reactive oxygen species (ROS). ROS has been associated with intestinal mucosal injury, increased intestinal permeability, enhanced gut bacterial overgrowth, and translocation; all these changes result in increased endotoxin and inflammation. Portal hypertension also results in the development of collateral circulation and reduces liver mass resulting in an overall increase in endotoxin/bacteria bypassing detoxication and immune clearance in the liver. Endotoxemia can in turn aggravate oxidative stress and inflammation, leading to a cycle of gut barrier dysfunction → endotoxemia → organ injury. The phenotype of cardiovascular abnormalities includes hyperdynamic circulation and cirrhotic cardiomyopathy. Oxidative stress is often accompanied by inflammation; thus, blocking oxidative stress can minimize the systemic inflammatory response and alleviate the severity of cardiovascular diseases. The present review aims to elucidate the role of oxidative stress in cirrhosis-associated cardiovascular abnormalities and discusses possible therapeutic effects of antioxidants on cardiovascular complications of cirrhosis including hyperdynamic circulation, cirrhotic cardiomyopathy, and hepatorenal syndrome.

Endotoxemia Correlates with Kidney Function and Length of Stay in Critically Ill Patients

INTRODUCTION

Endotoxin is a key driver of sepsis, which frequently causes acute kidney injury (AKI). However, endotoxins may also be found in non-bacteremic critically ill patients, likely from intestinal translocation. Preclinical models show that endotoxins can directly injure the kidneys, and in COVID-19 patients, endotoxemia correlated with AKI. We sought to determine correlations between endotoxemia and kidney and hospital outcomes in a broad group of critically ill patients.

METHODS

In this single-center, serial prospective study, 124 predominantly Caucasian adult patients were recruited within 48 h of admission to Stony Brook University Hospital Intensive Care Unit (ICU). Demographics, vital signs, laboratory data, and outcomes were collected. Circulating endotoxin was measured on days 1, 4, and 8 using the endotoxin activity assay (EAA). The association of EAA with outcomes was examined with EAA: (1) categorized as <0.6, ≥0.6, and nonresponders (NRs); and (2) used as a continuous variable.

RESULTS

Patients with EAA ≥0.6 had a higher prevalence of proteinuria, and lower arterial oxygen saturation (SaO2) to fraction of inspired oxygen (FiO2) (SaO2/FiO2) ratio versus patients with EAA <0.6. EAA levels positively correlated with serum creatinine (sCr) levels on day 1. Patients whose EAA level stayed ≥0.6 had a slower decline in sCr compared to those whose EAA started at ≥0.6 and subsequently declined. Patients with AKI stage 1 and EAA ≥0.6 on day 1 showed slower decline in sCr compared to patients with stage 1 AKI and EAA <0.6. EAA ≥0.6 and NR patients had longer hospital stay and delayed ICU discharge versus EAA <0.6.

CONCLUSIONS

High EAA levels correlated with worse kidney function and outcomes. Patients whose EAA levels fell, and those with AKI stage I and day 1 EAA <0.6 recovered more quickly compared to those with EAA ≥0.6, suggesting that removal of circulating endotoxins may be beneficial in critically ill patients.

Low-grade endotoxemia and risk of recurrent thrombosis in primary antiphospholipid syndrome. The multicenter ATHERO-APS study

INTRODUCTION

Low-grade endotoxemia is associated with systemic inflammation, enhanced oxidative stress and cardiovascular events in different clinical settings, but its possible role as "second hit" in patients with primary antiphospholipid syndrome (PAPS) has never been investigated.

PURPOSE

To evaluate the relationship between plasma lipopolysaccharide (LPS) levels, oxidative stress markers and risk of thrombosis in the prospective multicenter ATHERO-APS study.

METHODS

Baseline LPS, soluble NADPH-oxidase 2-derived peptide (sNOX-dp), H2O2 production, hydrogen peroxide breakdown activity (HBA), and nitric oxide (NO) bioavailability were compared in 97 PAPS, 16 non-thrombotic aPL carriers and 21 controls (CTRL) matched for age and sex. Correlations among laboratory variables were explored by Rho Spearman's correlation (rS). Cox-regression analysis was performed to assess the association between LPS and risk for a composite outcome of cardiovascular death, venous and arterial thromboembolism.

RESULTS

In the whole cohort (median age 51 years (IQR 43-60), 72 % female), PAPS demonstrated higher levels of LPS, sNOX-dp and H2O2 and lower levels of NO and HBA compared to non-thrombotic aPL carriers and CTRL. LPS levels were inversely correlated with HBA (rS: -0.295, p = 0.001) and NO (rS: -0.322, p < 0.001) and directly correlated with sNOX-dp (rS:0.469, p < 0.001) and H202 (rS:0.282, p < 0.001). PAPS showed higher levels of LPS, sNOX-dp and H2O2 and lower levels of NO and HBA compared to aPL carriers and CTRL. After a 4.7 years follow-up of, 11 composite outcomes were reported in PAPS (2.5 per 100 patient-years) while none was observed in aPL carriers. On Cox-regression analysis, patients with LPS above the median (>23.1 pg/ml) had a 5-fold increased risk of composite outcome compared to those with LPS below the median, after adjustment for sex, age, diabetes, and global antiphospholipid syndrome score.

CONCLUSION

Low-grade endotoxemia is associated with an increased oxidative stress and a higher risk of thrombosis in PAPS. Its prognostic value in carriers needs to be investigated in larger cohorts.

Gut barrier dysfunction and endotoxemia in heart failure: A dangerous connubium?

Heart failure (HF) is a leading cause of death worldwide despite recent advances in pharmacological treatments. Gut microbiota dysbiosis and gut barrier dysfunction with consequent bacterial translocation and increased blood endotoxemia has gained much attention as one of the key pathogenetic mechanisms contributing to increased mortality of patients at risk or with cardiovascular disease. Indeed, increased blood levels of lipopolysaccharide (LPS), a glycolipid of outer membrane of gut gram-negative bacteria, have been detected in patients with diabetes, obesity and nonalcoholic fatty liver disease or in patients with established coronary disease such as myocardial infarction or atrial fibrillation, suggesting endotoxemia as aggravating factor via systemic inflammation and eventually vascular damage. Upon interaction with its receptor Toll-like receptor 4 (TLR4) LPS may, in fact, act at different cellular levels so eliciting formation of proinflammatory cytokines or exerting a procoagulant activity. Increasing body of evidence pointed to endotoxemia as factor potentially deteriorating the clinical course of patients with HF, that, in fact, is associated with gut dysbiosis-derived changes of gut barrier functionality and eventually bacteria or bacterial product translocation into systemic circulation. The aim of this review is to summarize current experimental and clinical evidence on the mechanisms linking gut dysbiosis-related endotoxemia with HF, its potential negative impact with HF progression, and the therapeutic strategies that can counteract endotoxemia.

Therapeutic S100A8/A9 blockade inhibits myocardial and systemic inflammation and mitigates sepsis-induced myocardial dysfunction

BACKGROUND AND AIMS

The triggering factors of sepsis-induced myocardial dysfunction (SIMD) are poorly understood and are not addressed by current treatments. S100A8/A9 is a pro-inflammatory alarmin abundantly secreted by activated neutrophils during infection and inflammation. We investigated the efficacy of S100A8/A9 blockade as a potential new treatment in SIMD.

METHODS

The relationship between plasma S100A8/A9 and cardiac dysfunction was assessed in a cohort of 62 patients with severe sepsis admitted to the intensive care unit of Linköping University Hospital, Sweden. We used S100A8/A9 blockade with the small-molecule inhibitor ABR-238901 and S100A9-/- mice for therapeutic and mechanistic studies on endotoxemia-induced cardiac dysfunction in mice.

RESULTS

In sepsis patients, elevated plasma S100A8/A9 was associated with left-ventricular (LV) systolic dysfunction and increased SOFA score. In wild-type mice, 5 mg/kg of bacterial lipopolysaccharide (LPS) induced rapid plasma S100A8/A9 increase and acute LV dysfunction. Two ABR-238901 doses (30 mg/kg) administered intraperitoneally with a 6 h interval, starting directly after LPS or at a later time-point when LV dysfunction is fully established, efficiently prevented and reversed the phenotype, respectively. In contrast, dexamethasone did not improve cardiac function compared to PBS-treated endotoxemic controls. S100A8/A9 inhibition potently reduced systemic levels of inflammatory mediators, prevented upregulation of inflammatory genes and restored mitochondrial function in the myocardium. The S100A9-/- mice were protected against LPS-induced LV dysfunction to an extent comparable with pharmacologic S100A8/A9 blockade. The ABR-238901 treatment did not induce an additional improvement of LV function in the S100A9-/- mice, confirming target specificity.

CONCLUSION

Elevated S100A8/A9 is associated with the development of LV dysfunction in severe sepsis patients and in a mouse model of endotoxemia. Pharmacological blockade of S100A8/A9 with ABR-238901 has potent anti-inflammatory effects, mitigates myocardial dysfunction and might represent a novel therapeutic strategy for patients with severe sepsis.

Immunosuppressive effects of circulating bile acids in human endotoxemia and septic shock: patients with liver failure are at risk

BACKGROUND

Sepsis-induced immunosuppression is a frequent cause of opportunistic infections and death in critically ill patients. A better understanding of the underlying mechanisms is needed to develop targeted therapies. Circulating bile acids with immunosuppressive effects were recently identified in critically ill patients. These bile acids activate the monocyte G-protein coupled receptor TGR5, thereby inducing profound innate immune dysfunction. Whether these mechanisms contribute to immunosuppression and disease severity in sepsis is unknown. The aim of this study was to determine if immunosuppressive bile acids are present in endotoxemia and septic shock and, if so, which patients are particularly at risk.

METHODS

To induce experimental endotoxemia in humans, ten healthy volunteers received 2 ng/kg E. coli lipopolysaccharide (LPS). Circulating bile acids were profiled before and after LPS administration. Furthermore, 48 patients with early (shock onset within < 24 h) and severe septic shock (norepinephrine dose > 0.4 μg/kg/min) and 48 healthy age- and sex-matched controls were analyzed for circulating bile acids. To screen for immunosuppressive effects of circulating bile acids, the capability to induce TGR5 activation was computed for each individual bile acid profile by a recently published formula.

RESULTS

Although experimental endotoxemia as well as septic shock led to significant increases in total bile acids compared to controls, this increase was mild in most cases. By contrast, there was a marked and significant increase in circulating bile acids in septic shock patients with severe liver failure compared to healthy controls (61.8 µmol/L vs. 2.8 µmol/L, p = 0.0016). Circulating bile acids in these patients were capable to induce immunosuppression, as indicated by a significant increase in TGR5 activation by circulating bile acids (20.4% in severe liver failure vs. 2.8% in healthy controls, p = 0.0139).

CONCLUSIONS

Circulating bile acids capable of inducing immunosuppression are present in septic shock patients with severe liver failure. Future studies should examine whether modulation of bile acid metabolism can improve the clinical course and outcome of sepsis in these patients.

Endotoxemia Associated with Liver Disease Correlates with Systemic Inflammation and T Cell Exhaustion in Hepatitis C Virus Infection

Both acute and chronic hepatitis C virus (HCV) infections are characterized by inflammation. HCV and reduced liver blood filtration contribute to inflammation; however, the mechanisms of systemic immune activation and dysfunction as a result of HCV infection are not clear. We measured circulating inflammatory mediators (IL-6, IP10, sCD163, sCD14), indices of endotoxemia (EndoCab, LBP, FABP), and T cell markers of exhaustion and senescence (PD-1, TIGIT, CD57, KLRG-1) in HCV-infected participants, and followed a small cohort after direct-acting anti-viral therapy. IL-6, IP10, Endocab, LBP, and FABP were elevated in HCV participants, as were T cell co-expression of exhaustion and senescence markers. We found positive associations between IL-6, IP10, EndoCab, LBP, and co-expression of T cell markers of exhaustion and senescence. We also found numerous associations between reduced liver function, as measured by plasma albumin levels, and T cell exhaustion/senescence, inflammation, and endotoxemia. We found positive associations between liver stiffness (TE score) and plasma levels of IL-6, IP10, and LBP. Lastly, plasma IP10 and the proportion of CD8 T cells co-expressing PD-1 and CD57 decreased after initiation of direct-acting anti-viral therapy. Although associations do not prove causality, our results support the model that translocation of microbial products, resulting from decreased liver blood filtration, during HCV infection drives chronic inflammation that results in T cell exhaustion/senescence and contributes to systemic immune dysfunction.

Tissue factor expression in monocyte subsets during human immunothrombosis, endotoxemia and sepsis

INTRODUCTION

Tissue factor expression on monocytes is implicated in the pathophysiology of sepsis-induced coagulopathy. How tissue factor is expressed by monocyte subsets (classical, intermediate and non-classical) is unknown.

METHODS

Monocytic tissue factor surface expression was investigated during three conditions. Primary human monocytes and microvascular endothelial cell co-cultures were used for in vitro studies. Volunteers received a bolus of lipopolysaccharide (2 ng/kg) to induce endotoxemia. Patients with sepsis, or controls with critical illness unrelated to sepsis, were recruited from four intensive care units.

RESULTS

Contact with endothelium and stimulation with lipopolysaccharide reduced the proportion of intermediate monocytes. Lipopolysaccharide increased tissue factor surface expression on classical and non-classical monocytes. Endotoxemia induced profound, transient monocytopenia, along with activation of coagulation pathways. In the remaining circulating monocytes, tissue factor was up-regulated in intermediate monocytes, though approximately 60 % of individuals (responders) up-regulated tissue factor across all monocyte subsets. In critically ill patients, tissue factor expression on intermediate and non-classical monocytes was significantly higher in patients with established sepsis than among non-septic patients. Upon recovery of sepsis, expression of tissue factor increased significantly in classical monocytes.

CONCLUSION

Tissue factor expression in monocyte subsets varies significantly during health, endotoxemia and sepsis.

Are gut dysbiosis, barrier disruption, and endotoxemia related to adipose tissue dysfunction in metabolic disorders? Overview of the mechanisms involved

Recently, compelling evidence points to dysbiosis and disruption of the epithelial intestinal barrier as major players in the pathophysiology of metabolic disorders, such as obesity. Upon the intestinal barrier disruption, components from bacterial metabolism and bacteria itself can reach peripheral tissues through circulation. This has been associated with the low-grade inflammation that characterizes obesity and other metabolic diseases. While circulating bacterial DNA has been postulated as a common feature of obesity and even type 2 diabetes, almost no focus has been given to the existence and effects of bacteria in peripheral tissues, namely the adipose tissue. As a symbiont population, it is expected that gut microbiota modulate the immunometabolism of the host, thus influencing energy balance mechanisms and inflammation. Gut inflammatory signals cause direct deleterious inflammatory responses in adipose tissue and may also affect key gut neuroendocrine mechanisms governing nutrient sensing and energy balance, like incretins and ghrelin, which play a role in the gut-brain-adipose tissue axis. Thus, it is of major importance to disclose how gut microbiota and derived signals modulate neuroendocrine and inflammatory pathways, which contribute to the dysfunction of adipose tissue and to the metabolic sequelae of obesity and related disorders. This review summarizes the current knowledge regarding these topics and identifies new perspectives in this field of research, highlighting new pathways toward the reduction of the inflammatory burden of metabolic diseases.

GOLPH3 promotes endotoxemia-induced liver and kidney injury through Golgi stress-mediated apoptosis and inflammatory response

Sepsis is a serious clinical condition characterized by a systemic inflammatory response, a leading cause of acute liver and kidney injury, and is associated with a high morbidity and mortality. Understanding the molecular mechanisms underlying the acute liver and kidney injury is crucial for developing an effective therapy. Golgi apparatus plays important roles and has various substrates mediating cellular stress responses. Golgi phosphoprotein 3 (GOLPH3), linking Golgi membranes to the cytoskeleton, has been identified as an important oncogenic regulator; however, its role in endotoxemia-induced acute liver and kidney injury remains elusive. Here, we found that upregulation of GOLPH3 was associated with endotoxemia-induced acute liver and kidney injury. Lipopolysaccharide (LPS) treatment increased Golgi stress and fragmentation, and associated pro-inflammatory mediator (Tnfα, IL-6, and IL-1β) production in vivo and in vitro. Interestingly, the downregulation of GOLPH3 significantly decreased LPS-induced Golgi stress and pro-inflammatory mediators (Tnfα, IL-6, Mcp1, and Nos2), and reversed apoptotic cell deaths in LPS-treated hepatocytes and renal tubular cells. GOLPH3 knockdown also reduced inflammatory response in LPS-treated macrophages. The AKT/NF-kB signaling pathway was suppressed in GOLPH3 knockdown, which may be associated with a reduction of inflammatory response and apoptosis and the recovery of Golgi morphology and function. Taken together, GOLPH3 plays a crucial role in the development and progression of acute liver and kidney injury by promoting Golgi stress and increasing inflammatory response and apoptosis, suggesting GOLPH3 as a potential therapeutic target for endotoxemia-induced tissue injury.

DUSP1 interacts with and dephosphorylates VCP to improve mitochondrial quality control against endotoxemia-induced myocardial dysfunction

Dual specificity phosphatase 1 (DUSP1) and valosin-containing protein (VCP) have both been reported to regulate mitochondrial homeostasis. However, their impact on mitochondrial quality control (MQC) and myocardial function during LPS-induced endotoxemia remains unclear. We addressed this issue by modeling LPS-induced endotoxemia in DUSP1 transgenic (DUSP1TG) mice and in cultured DUSP1-overexpressing HL-1 cardiomyocytes. Accompanying characteristic structural and functional deficits, cardiac DUSP1 expression was significantly downregulated following endotoxemia induction in wild type mice. In contrast, markedly reduced myocardial inflammation, cardiomyocyte apoptosis, cardiac structural disorder, cardiac injury marker levels, and normalized systolic/diastolic function were observed in DUSP1TG mice. Furthermore, DUSP1 overexpression in HL-1 cells significantly attenuated LPS-mediated mitochondrial dysfunction by preserving MQC, as indicated by normalized mitochondrial dynamics, improved mitophagy, enhanced biogenesis, and attenuated mitochondrial unfolded protein response. Molecular assays showed that VCP was a substrate of DUSP1 and the interaction between DUSP1 and VCP primarily occurred on the mitochondria. Mechanistically, DUSP1 phosphatase domain promoted the physiological DUSP1/VCP interaction which prevented LPS-mediated VCP Ser784 phosphorylation. Accordingly, transfection with a phosphomimetic VCP mutant abolished the protective actions of DUSP1 on MQC and aggravated inflammation, apoptosis, and contractility/relaxation capacity in HL-1 cardiomyocytes. These findings support the involvement of the novel DUSP1/VCP/MQC pathway in the pathogenesis of endotoxemia-caused myocardial dysfunction.

Translation Rescue by Targeting Ppp1r15a through Its Upstream Open Reading Frame in Sepsis-Induced Acute Kidney Injury in a Murine Model

BACKGROUND

Translation shutdown is a hallmark of late-phase, sepsis-induced kidney injury. Methods for controlling protein synthesis in the kidney are limited. Reversing translation shutdown requires dephosphorylation of the eukaryotic initiation factor 2 (eIF2) subunit eIF2 α ; this is mediated by a key regulatory molecule, protein phosphatase 1 regulatory subunit 15A (Ppp1r15a), also known as GADD34.

METHODS

To study protein synthesis in the kidney in a murine endotoxemia model and investigate the feasibility of translation control in vivo by boosting the protein expression of Ppp1r15a, we combined multiple tools, including ribosome profiling (Ribo-seq), proteomics, polyribosome profiling, and antisense oligonucleotides, and a newly generated Ppp1r15a knock-in mouse model and multiple mutant cell lines.

RESULTS

We report that translation shutdown in established sepsis-induced kidney injury is brought about by excessive eIF2 α phosphorylation and sustained by blunted expression of the counter-regulatory phosphatase Ppp1r15a. We determined the blunted Ppp1r15a expression persists because of the presence of an upstream open reading frame (uORF). Overcoming this barrier with genetic and antisense oligonucleotide approaches enabled the overexpression of Ppp1r15a, which salvaged translation and improved kidney function in an endotoxemia model. Loss of this uORF also had broad effects on the composition and phosphorylation status of the immunopeptidome-peptides associated with the MHC-that extended beyond the eIF2 α axis.

CONCLUSIONS

We found Ppp1r15a is translationally repressed during late-phase sepsis because of the existence of an uORF, which is a prime therapeutic candidate for this strategic rescue of translation in late-phase sepsis. The ability to accurately control translation dynamics during sepsis may offer new paths for the development of therapies at codon-level precision.

PODCAST

This article contains a podcast at.

Postbiotics engage IRF4 in adipocytes to promote sex-dependent changes in blood glucose during obesity

Postbiotics are microbial-derived components or metabolites that can influence host immunity and metabolism. Some postbiotics can improve blood glucose control and lower inflammation during bacterial or nutritional stress. Bacterial cell wall-derived muramyl dipeptide (MDP) is a potent insulin-sensitizing postbiotic that engages NOD2, RIPK2, and requires interferon regulatory factor 4 (IRF4) to lower inflammation and improve blood glucose. However, the sex-dependent effects of this postbiotic and the cell type required for IRF4 to cause inflammatory versus glycemic responses to MDP were unknown. Here, we measured how MDP injection altered glucose tolerance and adipose tissue inflammation during low-level endotoxemia and high fat diet (HFD)-induced obesity in male and female adipocyte-specific IRF4 knockout mice (AdipoIRF4fl/fl ) compared to WTfl/fl mice. Adipocyte IRF4 was required for the blood glucose-lowering effects of MDP during endotoxemia and HFD-induced obesity in male mice. However, MDP did not alter blood glucose in female WTfl/fl and AdipoIRF4fl/f mice during endotoxemia. Unexpectedly, female HFD-fed AdipoIRF4fl/f mice had lower blood glucose after MDP treatment compared to WTfl/fl mice. MDP lowered inflammatory gene expression in adipose tissue of HFD-fed WTfl/fl and AdipoIRF4fl/fl mice of both sexes. Therefore, MDP-mediated lowering of adipose inflammation does not require adipocyte IRF4 and was independent of sex. Together, these data show that injection of MDP, an insulin-sensitizing postbiotic, lowers adipose tissue inflammation in male and female mice, but lower adipose inflammation is not always associated with improved blood glucose. The blood glucose-lowering effect of the postbiotic MDP and dependence on adipocyte IRF4 is sex-dependent.

Peroxisome proliferator-activated receptor-alpha activation and dipeptidyl peptidase-4 inhibition target dysbiosis to treat fatty liver in obese mice

BACKGROUND

Obesity and comorbidities onset encompass gut dysbiosis, altered intestinal permeability, and endotoxemia. Treatments that target gut dysbiosis can cope with obesity and nonalcoholic fatty liver disease (NAFLD) management. Peroxisome proliferator-activated receptor (PPAR)-alpha activation and dipeptidyl-peptidase-4 (DPP-4) inhibition alleviate NAFLD, but the mechanism may involve gut microbiota modulation and merits further investigation.

AIM

To address the effects of PPAR-alpha activation and DPP-4 inhibition (isolated or combined) upon the gut-liver axis, emphasizing inflammatory pathways in NAFLD management in high-fat-fed C57BL/6J mice.

METHODS

Male C57BL/6J mice were fed a control diet (C, 10% of energy as lipids) or a high-fat diet (HFD, 50% of energy as lipids) for 12 wk, when treatments started, forming the groups: C, HF, HFA (HFD + PPAR-alpha agonist WY14643, 2.5 mg/kg body mass), HFL (HFD + DPP-4 inhibitor linagliptin, 15 mg/kg body mass), and HFC (HFD + the combination of WY14643 and linagliptin).

RESULTS

The HFD was obesogenic compared to the C diet. All treatments elicited significant body mass loss, and the HFC group showed similar body mass to the C group. All treatments tackled oral glucose intolerance and raised plasma glucagon-like peptide-1 concentrations. These metabolic benefits restored Bacteroidetes/Firmicutes ratio, resulting in increased goblet cells per area of the large intestine and reduced lipopolysaccharides concentrations in treated groups. At the gene level, treated groups showed higher intestinal Mucin 2, Occludin, and Zo-1 expression than the HFD group. The reduced endotoxemia suppressed inflammasome and macrophage gene expression in the liver of treated animals. These observations complied with the mitigation of liver steatosis and reduced hepatic triacylglycerol, reassuring the role of the proposed treatments on NAFLD mitigation.

CONCLUSION

PPAR alpha activation and DPP-4 inhibition (isolated or combined) tackled NAFLD in diet-induced obese mice by restoration of gut-liver axis. The reestablishment of the intestinal barrier and the rescued phylogenetic gut bacteria distribution mitigated liver steatosis through anti-inflammatory signals. These results can cope with NAFLD management by providing pre-clinical evidence that drugs used to treat obesity comorbidities can help to alleviate this silent and harmful liver disease.

Pioglitazone Ameliorates Acute Endotoxemia-Induced Acute on Chronic Renal Dysfunction in Cirrhotic Ascitic Rats

Endotoxemia-activated tumor necrosis factor (TNFα)/nuclear factor kappa B (NFκB) signals result in acute on chronic inflammation-driven renal dysfunction in advanced cirrhosis. Systemic activation of peroxisome proliferator-activated receptor gamma (PPARγ) with pioglitazone can suppress inflammation-related splanchnic and pulmonary dysfunction in cirrhosis. This study explored the mechanism and effects of pioglitazone treatment on the abovementioned renal dysfunction in cirrhotic rats. Cirrhotic ascitic rats were induced with renal dysfunction by bile duct ligation (BDL). Then, 2 weeks of pioglitazone treatment (Pio, PPAR gamma agonist, 12 mg/kg/day, using the azert osmotic pump) was administered from the 6th week after BDL. Additionally, acute lipopolysaccharide (LPS, Escherichia coli 0111:B4; Sigma, 0.1 mg/kg b.w, i.p. dissolved in NaCl 0.9%) was used to induce acute renal dysfunction. Subsequently, various circulating, renal arterial and renal tissue pathogenic markers were measured. Cirrhotic BDL rats are characterized by decreased mean arterial pressure, increased cardiac output and portal venous pressure, reduced renal arterial blood flow (RABF), increased renal vascular resistance (RVR), increased relative renal weight/hydroxyproline, downregulated renal PPARγ expression, upregulated renal inflammatory markers (TNFα, NFκB, IL-6, MCP-1), increased adhesion molecules (VCAM-1 and ICAM-1), increased renal macrophages (M1, CD68), and progressive renal dysfunction (increasing serum and urinary levels of renal injury markers (lipocalin-2 and IL-18)). In particular, acute LPS administration induces acute on chronic renal dysfunction (increasing serum BUN/creatinine, increasing RVR and decreasing RABF) by increased TNFα-NFκB-mediated renal inflammatory markers as well as renal M1 macrophage infiltration. In comparison with the BDL+LPS group, chronic pioglitazone pre-treatment prevented LPS-induced renal pathogenic changes in the BDL-Pio+LPS group. Activation of systemic, renal vessel and renal tissue levels of PPARγ by chronic pioglitazone treatment has beneficial effects on the endotoxemia-related TNFα/NFκB-mediated acute and chronic renal inflammation in cirrhosis. This study revealed that normalization of renal and renal arterial levels of PPARγ effectively prevented LPS-induced acute and chronic renal dysfunction in cirrhotic ascitic rats.

Prevention of endotoxin-induced cardiomyopathy using sodium tanshinone IIA sulfonate: Involvement of augmented autophagy and NLRP3 inflammasome suppression

Increasing evidence indicates that patients or experimental animals exposure to endotoxin (lipopolysaccharides, LPS) exert deleterious cardiac functions that greatly contribute to morbidity and mortality. The pathophysiologic processes, including NLRP3 inflammasome overactivation and cardiac inflammatory injury, are complicated. Sodium tanshinone IIA sulfonate (STS), a water-soluble derivative of tanshinone IIA, is a naturally occurring compound extracted from Salvia miltiorrhiza and has anti-inflammatory and cardioprotective properties. In this study we examined the effect of STS on endotoxin-induced cardiomyopathy and investigated the underlying mechanisms. An endotoxemic mouse model was established by injecting LPS (10 mg/kg). Different doses of STS were administered intraperitoneally (5, 10, or 50 mg/kg) at different time points (2/12 h, 4/12 h, and 8/12 h) after LPS challenge to assess its effect on survival of mice with endotoxemia. In parallel, cardiac function, myocardial inflammatory cytokines, cardiomyocyte pyroptosis and autophagy were evaluated to determine the extent of myocardial damage due to sepsis in the presence and absence of STS at the optimal dose (10 mg/kg) and time-point (2/12 h). The results demonstrated that STS increased the survival rates, improved the compromised cardiac function and reduced myocardial inflammatory injury associated with enhanced autophagy and mitigated NLRP3 inflammasome activation. Moreover, inhibiting of autophagy or blocking the AMPK pathway reversed STS-elicited prevention of cardiomyopathy and activated the NLRP3 inflammasome in endotoxemic mice. Collectively, our study demonstrates that STS attenuates endotoxemia-induced mortality and cardiomyopathy, which may be associated with promotion of autophagy and inhibition of NLRP3 inflammasome overactivation.

Renal Denervation Exacerbates LPS- and Antibody-induced Acute Kidney Injury, but Protects from Pyelonephritis in Mice

BACKGROUND

Renal denervation (RDN) is an invasive intervention to treat drug-resistant arterial hypertension. Its therapeutic value is contentious. Here we examined the effects of RDN on inflammatory and infectious kidney disease models in mice.

METHODS

Mice were unilaterally or bilaterally denervated, or sham operated, then three disease models were induced: nephrotoxic nephritis (NTN, a model for crescentic GN), pyelonephritis, and acute endotoxemic kidney injury (as a model for septic kidney injury). Analytical methods included measurement of renal glomerular filtration, proteinuria, flow cytometry of renal immune cells, immunofluorescence microscopy, and three-dimensional imaging of optically cleared kidney tissue by light-sheet fluorescence microscopy followed by algorithmic analysis.

RESULTS

Unilateral RDN increased glomerular filtration in denervated kidneys, but decreased it in the contralateral kidneys. In the NTN model, more nephritogenic antibodies were deposited in glomeruli of denervated kidneys, resulting in stronger inflammation and injury in denervated compared with contralateral nondenervated kidneys. Also, intravenously injected LPS increased neutrophil influx and inflammation in the denervated kidneys, both after unilateral and bilateral RDN. When we induced pyelonephritis in bilaterally denervated mice, both kidneys contained less bacteria and neutrophils. In unilaterally denervated mice, pyelonephritis was attenuated and intrarenal neutrophil numbers were lower in the denervated kidneys. The nondenervated contralateral kidneys harbored more bacteria, even compared with sham-operated mice, and showed the strongest influx of neutrophils.

CONCLUSIONS

Our data suggest that the increased perfusion and filtration in denervated kidneys can profoundly influence concomitant inflammatory diseases. Renal deposition of circulating nephritic material is higher, and hence antibody- and endotoxin-induced kidney injury was aggravated in mice. Pyelonephritis was attenuated in denervated murine kidneys, because the higher glomerular filtration facilitated better flushing of bacteria with the urine, at the expense of contralateral, nondenervated kidneys after unilateral denervation.

Effects of a Peripherally Restricted Hybrid Inhibitor of CB1 Receptors and iNOS on Alcohol Drinking Behavior and Alcohol-Induced Endotoxemia

Alcohol consumption is associated with gut dysbiosis, increased intestinal permeability, endotoxemia, and a cascade that leads to persistent systemic inflammation, alcoholic liver disease, and other ailments. Craving for alcohol and its consequences depends, among other things, on the endocannabinoid system. We have analyzed the relative role of central vs. peripheral cannabinoid CB1 receptors (CB1R) using a "two-bottle" as well as a "drinking in the dark" paradigm in mice. The globally acting CB1R antagonist rimonabant and the non-brain penetrant CB1R antagonist JD5037 inhibited voluntary alcohol intake upon systemic but not upon intracerebroventricular administration in doses that elicited anxiogenic-like behavior and blocked CB1R-induced hypothermia and catalepsy. The peripherally restricted hybrid CB1R antagonist/iNOS inhibitor S-MRI-1867 was also effective in reducing alcohol consumption after oral gavage, while its R enantiomer (CB1R inactive/iNOS inhibitor) was not. The two MRI-1867 enantiomers were equally effective in inhibiting an alcohol-induced increase in portal blood endotoxin concentration that was caused by increased gut permeability. We conclude that (i) activation of peripheral CB1R plays a dominant role in promoting alcohol intake and (ii) the iNOS inhibitory function of MRI-1867 helps in mitigating the alcohol-induced increase in endotoxemia.

Cardiac and Brainstem Neuroinflammatory Pathways Account for Androgenic Incitement of Cardiovascular and Autonomic Manifestations in Endotoxic Male Rats

ABSTRACT

Inconsistent reports are available on the role of testosterone in end-organ damage caused by endotoxemia. Here, pharmacologic, surgical, and molecular studies were employed to assess the testosterone modulation of cardiovascular, autonomic, and peripheral and central inflammatory derangements caused by endotoxemia. Studies were performed in conscious male rats preinstrumented with femoral indwelling catheters for the measurement of blood pressure and subjected to castration or pharmacologic interventions that interrupt the biosynthetic cascade of testosterone. Compared with the effects of lipopolysaccharide (10 mg/kg intravenously) in sham operated rats, 2-week castration reduced the lipopolysaccharide-evoked (1) falls in blood pressure, (2) decreases in time- and frequency-domain indices of heart rate variability, (3) shifts in spectral measures of cardiac sympathovagal balance toward parasympathetic dominance, and (4) increases in protein expressions of toll-like receptor-4 and monocyte chemoattractant protein-1 in heart and medullary neurons of the nucleus tractus solitarius and rostral ventrolateral medulla. While the ameliorating actions of castration on endotoxic cardiovascular manifestations were maintained after testosterone replacement, the concomitant inflammatory signals were restored to near-sham levels. The favorable influences of castration on inflammatory and cardiovascular abnormalities of endotoxemia were replicated in intact rats pretreated with degarelix (gonadotropin-releasing hormone receptor blocker) or finasteride (5α-reductase inhibitor) but not formestane (aromatase inhibitor). The data signifies the importance of androgens and its biosynthetic enzymes in cardiovascular and autonomic insults induced by the endotoxic inflammatory response. Clinically, the interruption of testosterone biosynthesis could offer a potential strategy for endotoxemia management.

Frontline Science: The expression of integrin αD β2 (CD11d/CD18) on neutrophils orchestrates the defense mechanism against endotoxemia and sepsis

Neutrophil-macrophage interplay is a fine-tuning mechanism that regulates the innate immune response during infection and inflammation. Cell surface receptors play an essential role in neutrophil and macrophage functions. The same receptor can provide different outcomes within diverse leukocyte subsets in different inflammatory conditions. Understanding the variety of responses mediated by one receptor is critical for the development of anti-inflammatory treatments. In this study, we evaluated the role of a leukocyte adhesive receptor, integrin αD β2 , in the development of acute inflammation. αD β2 is mostly expressed on macrophages and contributes to the development of chronic inflammation. In contrast, we found that αD -knockout dramatically increases mortality in the cecal ligation and puncture sepsis model and LPS-induced endotoxemia. This pathologic outcome of αD -deficient mice is associated with a reduced number of monocyte-derived macrophages and an increased number of neutrophils in their lungs. However, the tracking of adoptively transferred fluorescently labeled wild-type (WT) and αD-/- monocytes in WT mice during endotoxemia demonstrated only a moderate difference between the recruitment of these two subsets. Moreover, the rescue experiment, using i.v. injection of WT monocytes to αD -deficient mice followed by LPS challenge, showed only slightly reduced mortality. Surprisingly, the injection of WT neutrophils to the bloodstream of αD-/- mice markedly increased migration of monocyte-derived macrophage to lungs and dramatically improves survival. αD -deficient neutrophils demonstrate increased necrosis/pyroptosis. αD β2 -mediated macrophage accumulation in the lungs promotes efferocytosis that reduced mortality. Hence, integrin αD β2 implements a complex defense mechanism during endotoxemia, which is mediated by macrophages via a neutrophil-dependent pathway.

Effect of forkhead box O1 in renal tubular epithelial cells on endotoxin-induced acute kidney injury

Mitochondrial damage in renal tubular epithelial cells (RTECs) is a hallmark of endotoxin-induced acute kidney injury (AKI). Forkhead box O1 (FOXO1) is responsible for regulating mitochondrial function and is involved in several kidney diseases. Here, we investigated the effect of FOXO1 on endotoxin-induced AKI and the related mechanism. In vivo, FOXO1 downregulation in mouse RTECs and mitochondrial damage were found in endotoxin-induced AKI. Overexpression of FOXO1 by kidney focal adeno-associated virus (AAV) delivery improved renal function and reduced mitochondrial damage. Peroxisome proliferator-activated receptor-γ coactivator 1-α (PGC1-α), a master regulator of mitochondrial biogenesis and function, was reduced in endotoxin-induced AKI, but the reduction was reversed by FOXO1 overexpression. In vitro, exposure to LPS led to a decline in HK-2 cell viability, mitochondrial fragmentation, and mitochondrial superoxide accumulation, as well as downregulation of FOXO1, PGC1-α, and mitochondrial complex I/V. Moreover, overexpression of FOXO1 in HK-2 cells increased HK-2 cell viability and PGC1-α expression, and it alleviated the mitochondrial injury and superoxide accumulation induced by LPS. Meanwhile, inhibition of FOXO1 in HK-2 cells by siRNA treatment decreased PGC1-α expression and HK-2 cell viability. Chromatin immunoprecipitation assays and PCR analysis confirmed that FOXO1 bound to the PGC1-α promoter in HK-2 cells. In conclusion, downregulation of FOXO1 in RTECs mediated endotoxin-induced AKI and mitochondrial damage. Overexpression of FOXO1 could improve renal injury and mitochondrial dysfunction, and this effect occurred at least in part as a result of PGC1-α signaling. FOXO1 might be a potential target for the prevention and treatment of endotoxin-induced AKI.

Suppression of Hypoxia-Inducible Factor 1α by Low-Molecular-Weight Heparin Mitigates Ventilation-Induced Diaphragm Dysfunction in a Murine Endotoxemia Model

Mechanical ventilation (MV) is required to maintain life for patients with sepsis-related acute lung injury but can cause diaphragmatic myotrauma with muscle damage and weakness, known as ventilator-induced diaphragm dysfunction (VIDD). Hypoxia-inducible factor 1α (HIF-1α) plays a crucial role in inducing inflammation and apoptosis. Low-molecular-weight heparin (LMWH) was proven to have anti-inflammatory properties. However, HIF-1α and LMWH affect sepsis-related diaphragm injury has not been investigated. We hypothesized that LMWH would reduce endotoxin-augmented VIDD through HIF-1α. C57BL/6 mice, either wild-type or HIF-1α–deficient, were exposed to MV with or without endotoxemia for 8 h. Enoxaparin (4 mg/kg) was administered subcutaneously 30 min before MV. MV with endotoxemia aggravated VIDD, as demonstrated by increased interleukin-6 and macrophage inflammatory protein-2 levels, oxidative loads, and the expression of HIF-1α, calpain, caspase-3, atrogin-1, muscle ring finger-1, and microtubule-associated protein light chain 3-II. Disorganized myofibrils, disrupted mitochondria, increased numbers of autophagic and apoptotic mediators, substantial apoptosis of diaphragm muscle fibers, and decreased diaphragm function were also observed (p < 0.05). Endotoxin-exacerbated VIDD and myonuclear apoptosis were attenuated by pharmacologic inhibition by LMWH and in HIF-1α–deficient mice (p < 0.05). Our data indicate that enoxaparin reduces endotoxin-augmented MV-induced diaphragmatic injury, partially through HIF-1α pathway inhibition.

DOCK2 contributes to endotoxemia-induced acute lung injury in mice by activating proinflammatory macrophages

Dedicator of cytokinesis 2 (DOCK2), an atypical Rac activator, has important anti-inflammatory properties in blepharitis, enteric bacterial infection and colitis. However, the roles of DOCK2 in macrophage activation and acute lung injury (ALI) are still poorly elucidated. In vitro studies demonstrated that DOCK2 was essential for the nucleotide-sensing Toll-like receptor (TLR) 4-mediated inflammatory response in macrophages. We also confirmed that exposure of macrophages to LPS induced Rac activation through a TLR4-independent, DOCK2-dependent mechanism. Phosphorylation of IκB kinase (IKK) β and nuclear translocation of transcription factor nuclear factor kappa B (NF-κB) were impaired in Ad-shDOCK2-expressing macrophages, resulting in a decreased inflammatory response. Similar results were obtained when EHop-016 (a Rac inhibitor) was used to treat uninfected macrophages. In summary, these data indicate that the DOCK2-Rac signaling pathway acts in parallel with TLR4 engagement to control IKKβ activation for inflammatory cytokine release. Next, we investigated whether pharmacological inhibition of DOCK2 protects against endotoxemia-induced lung injury in mice. Treatment with 4-[3'-(2″-chlorophenyl)-2'-propen-1'-ylidene]-1-phenyl-3,5-pyrazolidinedione (CPYPP), a small-molecule inhibitor of DOCK2, reduced the severity of lung injury, as indicated by decreases in the lung injury score and myeloperoxidase (MPO) activity. Moreover, CPYPP attenuated LPS-induced proinflammatory cytokine release in mice. Our studies suggest that inhibition of DOCK2 may suppress LPS-induced macrophage activation and that DOCK2 may be a novel target for treating endotoxemia-related ALI.

Central Administration of Angiotensin-(1-7) Improves Vasopressin Impairment and Hypotensive Response in Experimental Endotoxemia

Angiotensin-(1-7) [Ang-(1-7)]/Mas receptor is a counter-regulatory axis that counteracts detrimental renin-angiotensin system (RAS) effects, especially regarding systemic inflammation, vasopressin (AVP) release, and hypothalamic-pituitary-adrenal (HPA) activation. However, it is not completely understood whether this system may control centrally or systemically the late phase of systemic inflammation. Thus, the aim of this study was to determine whether intracerebroventricular (i.c.v.) administration of Ang-(1-7) can modulate systemic inflammation through the activation of humoral pathways in late phase of endotoxemia. Endotoxemia was induced by systemic injection of lipopolysaccharide (LPS) (1.5 mg/kg, i.v.) in Wistar rats. Ang-(1-7) (0.3 nmol in 2 µL) promoted the release of AVP and attenuated interleukin-6 (IL-6) and nitric oxide (NO) levels but increased interleukin-10 (IL-10) in the serum of the endotoxemic rats. The central administration of Mas receptor antagonist A779 (3 nmol in 2 µL, i.c.v.) abolished these anti-inflammatory effects in endotoxemic rats. Furthermore, Ang-(1-7) applied centrally restored mean arterial blood pressure (MABP) without affecting heart rate (HR) and prevented vascular hyporesponsiveness to norepinephrine (NE) and AVP in animals that received LPS. Together, our results indicate that Ang-(1-7) applied centrally promotes a systemic anti-inflammatory effect through the central Mas receptor and activation of the humoral pathway mediated by AVP.

High glucose load and endotoxemia among overweight and obese Arab women with and without diabetes: An observational study

Dietary intake influences gut microbiota activity. Nevertheless, there is a lack of evidence available that illustrates the acute effects of high glucose meal on metabolic endotoxemia. The present study assessed the acute impact of high glucose meal on endotoxemia and other clinical parameters in Saudi females with varying degrees of glycemia.The subjects were 64 consenting pre-menopausal women, grouped into 3: control [n = 14 lean, non-T2DM, BMI = 22.2 ± 2.2 kg/m]; overweight [n = 16, non-T2DM, BMI = 28.5 ± 1.5 kg/m] and T2DM [n = 34, BMI = 35.2 ± 7.7 kg/m]. After an overnight fast, all subjects were given a standardized high-glucose (75 g) meal. Anthropometrics were taken and blood samples were withdrawn at baseline and postprandial (0, 2 and 4-hours), serum glucose, endotoxin and lipid profile were quantified.At baseline, total cholesterol, LDL-cholesterol, triglycerides and serum glucose levels were significantly higher (P values <.01) whereas significantly lower HDL-cholesterol levels (P < .01) were observed in T2DM subjects compared to other groups. Baseline endotoxin levels were highest in the overweight group (3.2 ± 1.1 mmol/L) as compared to control (2.0 ± 0.5 mmol/L) and T2DM (2.7 ± 1.2 mmol/L) (P = .046). HDL-cholesterol, LDL-cholesterol and triglycerides, significantly decreased in the T2DM group after 2 hours (P values <.05), whereas unremarkable changes observed in other groups. Lastly, endotoxin levels significantly increased only in the overweight group (3.2 ± 1.1 vs 4.2 ± 1.4 mmol/L; P < .05), 4 hours postprandial.High glucose meal elevates endotoxemia only among overweight subjects and impairs dysbiosis.

Pre-exposure to mechanical ventilation and endotoxemia increases Pseudomonas aeruginosa growth in lung tissue during experimental porcine pneumonia

Background

Immune system suppression during critical care contributes to the risk of acquired bacterial infections with Pseudomonas (P.) aeruginosa. Repeated exposure to endotoxin can attenuate systemic inflammatory cytokine responses. Mechanical ventilation affects the systemic inflammatory response to various stimuli.

Aim

To study the effect of pre-exposure to mechanical ventilation with and without endotoxin-induced systemic inflammation on P. aeruginosa growth and wet-to-dry weight measurements on lung tissue and plasma and bronchoalveolar lavage levels of tumor necrosis factor alpha, interleukins 6 and 10.

Methods

Two groups of pigs were exposed to mechanical ventilation for 24 hours before bacterial inoculation and six h of experimental pneumonia (total experimental time 30 h): A_30h+Etx (n = 6, endotoxin 0.063 μg x kg^-1 x h^-1) and B_30h (n = 6, saline). A third group, C_6h (n = 8), started the experiment at the bacterial inoculation unexposed to endotoxin or mechanical ventilation (total experimental time 6 h). Bacterial inoculation was performed by tracheal instillation of 1x10¹¹ colony-forming units of P. aeruginosa. Bacterial cultures and wet-to-dry weight ratio analyses were done on lung tissue samples postmortem. Separate group comparisons were done between A_30h+Etx vs.B_30h (Inflammation) and B_30h vs. C_6h (Ventilation Time) during the bacterial phase of 6 h.

Results

P. aeruginosa growth was highest in A_30h+Etx, and lowest in C_6h (Inflammation and Ventilation Time both p<0.05). Lung wet-to-dry weight ratios were highest in A_30h+Etx and lowest in B_30h (Inflammation p<0.01, Ventilation Time p<0.05). C_6h had the highest TNF-α levels in plasma (Ventilation Time p<0.01). No differences in bronchoalveolar lavage variables between the groups were observed.

Conclusions

Mechanical ventilation and systemic inflammation before the onset of pneumonia increase the growth of P. aeruginosa in lung tissue. The attenuated growth of P. aeruginosa in the non-pre-exposed animals (C_6h) was associated with a higher systemic TNF-α production elicited from the bacterial challenge.

Protective effects of rolipram on endotoxic cardiac dysfunction via inhibition of the inflammatory response in cardiac fibroblasts

BACKGROUND

Cardiac fibroblasts, regarded as the immunomodulatory hub of the heart, have been thought to play an important role during sepsis-induced cardiomyopathy (SIC). However, the detailed molecular mechanism and targeted therapies for SIC are still lacking. Therefore, we sought to investigate the likely protective effects of rolipram, an anti-inflammatory drug, on lipopolysaccharide (LPS)-stimulated inflammatory responses in cardiac fibroblasts and on cardiac dysfunction in endotoxic mice.

METHOD

Cardiac fibroblasts were isolated and stimulated with 1 μg/ml LPS for 6 h, and 10 μmol/l rolipram was administered for 1 h before LPS stimulation. mRNA levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and interleukin-1β (IL-1β) in fibroblasts and their protein concentrations in supernatant were measured with real-time PCR (rt-PCR) and enzyme-linked immunosorbent assay, respectively. The expression of dual specificity phosphatase 1 (DUSP1), an endogenous negative regulator that inactivates MAPK-mediated inflammatory pathways, was also measured by rt-PCR and western blotting. DUSP1-targeted small interfering RNA (siRNA) was used to examine the specific role of DUSP1. To evaluate the role of rolipram in vivo, an endotoxic mouse model was established by intraperitoneal injection of 15 mg/kg LPS, and 10 mg/kg rolipram was intraperitoneally injected 1 h before LPS injection. mRNA and protein levels of inflammatory cytokines and DUSP1 in heart, inflammatory cell infiltration and cardiac function were all examined at 6 h after LPS injection.

RESULTS

The results showed that LPS could increase the expression and secretion of inflammatory cytokines and decrease the transcription and expression of DUSP1 in cardiac fibroblasts. However, rolipram pretreatment significantly reversed the LPS-induced downregulation of DUSP1 and inhibited LPS-induced upregulation and secretion of TNF-α and IL-6 but not IL-1β. Moreover, DUSP1-targeted siRNA experiments indicated that the protective effect of rolipram on inflammatory response was specific dependent on DUSP1 expression. Moreover, rolipram could further reduce inflammatory cell infiltration scores as shown by pathological analysis and increase the ejection fraction (EF) detected with echocardiography in the hearts of endotoxic mice.

CONCLUSIONS

Rolipram could improve endotoxin-induced cardiac dysfunction by upregulating DUSP1 expression to inhibit the inflammatory response in cardiac fibroblasts, which may be a potential treatment for SIC.

Targeting ROS and cPLA2/COX2 Expressions Ameliorated Renal Damage in Obese Mice with Endotoxemia

Obesity is associated with metabolic endotoxemia, reactive oxygen species (ROS), chronic inflammation, and obese kidney fibrosis. Although the fat–intestine–kidney axis has been documented, the pathomechanism and therapeutic targets of obese kidney fibrosis remain unelucidated. To mimic obese humans with metabolic endotoxemia, high-fat-diet-fed mice (HF group) were injected with lipopolysaccharide (LPS) to yield the obese kidney fibrosis–metabolic endotoxemia mouse model (HL group). Therapeutic effects of ROS, cytosolic phospholipases A2 (cPLA2) and cyclooxygenase-2 (COX-2) inhibitors were analyzed with a quantitative comparison of immunohistochemistry stains and morphometric approach in the tubulointerstitium of different groups. Compared with basal and HF groups, the HL group exhibited the most prominent obese kidney fibrosis, tubular epithelial lipid vacuoles, and lymphocyte infiltration in the tubulointerstitium. Furthermore, inhibitors of nonspecific ROS, cPLA2 and COX-2 ameliorated the above renal damages. Notably, the ROS-inhibitor-treated group ameliorated not only oxidative injury but also the expression of cPLA2 and COX-2, indicating that ROS functions as the upstream signaling molecule in the inflammatory cascade of obese kidney fibrosis. ROS acts as a key messenger in the signaling transduction of obese kidney fibrosis, activating downstream cPLA2 and COX-2. The given antioxidant treatment ameliorates obese kidney fibrosis resulting from a combined high-fat diet and LPS—ROS could serve as a potential therapeutic target of obese kidney fibrosis with metabolic endotoxemia.

Spatial Heterogeneity of Lung Strain and Aeration and Regional Inflammation During Early Lung Injury Assessed with PET/CT

INTRODUCTION

Spatial heterogeneity of lung aeration and strain (change volume/resting volume) occurs at microscopic levels and contributes to lung injury. Yet, it is mostly assessed with histograms or large regions-of-interest. Spatial heterogeneity could also influence regional gene expression. We used positron emission tomography (PET)/computed tomography (CT) to assess the contribution of different length-scales to mechanical heterogeneity and to direct lung injury biological pathway identification.

MATERIALS AND METHODS

Sheep exposed to mild (n = 5, supine and n = 3, prone) and moderate (n = 6, supine) systemic endotoxemia were protectively ventilated. At baseline, 6 hours and 20 hours length-scale analysis was applied to aeration in CT (mild groups) and PET transmission (moderate group) scans; and voxel-level strain derived from image registration of end-inspiratory and end-expiratory CTs (mild). 2-deoxy-2-[(18)F]fluoro-d-glucose (18F-FDG)-PET kinetics parameters in ventral and dorsal regions were correlated with tissue microarray gene expression (moderate).

RESULTS

While aeration and strain heterogeneity were highest at 5-10 mm length-scales, larger length-scales contained a higher fraction of strain than aeration heterogeneity. Contributions of length-scales >5-10 mm to aeration and strain heterogeneity increased as lung injury progressed (p < 0.001) and were higher in supine than prone animals. Genes expressed with regional correlation to 18F-FDG-PET kinetics (|r| = 0.81 [0.78-0.85]) yielded pathways associated with immune system activation and fluid clearance.

CONCLUSION

Normal spatial heterogeneity of aeration and strain suggest larger anatomical and functional determinants of lung strain than aeration heterogeneity. Lung injury and supine position increase the contribution of larger length-scales. 18F-FDG-PET-based categorization of gene expression results in known and novel biological pathways relevant to lung injury.

Novel reprogramming of neutrophils modulates inflammation resolution during atherosclerosis

Nonresolving inflammation perpetuated by innate leukocytes is involved in the pathogenesis of unstable atherosclerosis. However, the role and regulation of neutrophils related to nonresolving inflammation and atherosclerosis are poorly understood. We report herein that chronic subclinical endotoxemia, a risk factor for atherosclerosis, skewed neutrophils into a nonresolving inflammatory state with elevated levels of inflammatory mediators (Dectin-1, MMP9, and LTB4) and reduced levels of homeostatic mediators (LRRC32, TGFβ, and FPN). The polarization of neutrophils was due to ROS-mediated activation of oxCAMKII, caused by altered peroxisome homeostasis and reduced lysosome fusion. Application of 4-phenylbutyrate (4-PBA) enhanced peroxisome homeostasis of neutrophils, reduced oxCAMKII, and rebalanced the expression profiles of pro- and anti-inflammatory mediators. Adoptive transfer of neutrophils programmed by subclinical endotoxemia rendered exacerbated atherosclerosis. In contrast, transfer of ex vivo programmed neutrophils by 4-PBA reduced the pathogenesis of atherosclerosis. Our data define novel neutrophil dynamics associated with the progression and regression of atherosclerosis.

Polymyxin B hemoperfusion in endotoxemic septic shock patients without extreme endotoxemia: a post hoc analysis of the EUPHRATES trial

PURPOSE

The EUPHRATES trial examined the impact of polymyxin B hemoperfusion (PMX) on mortality in patients with septic shock and endotoxemia, defined as EAA ≥ 0.60. No difference was found in 28-day all-cause mortality. However, the trial showed that in some patients with septic shock the burden of endotoxin activity was extreme (EAA ≥ 0.9). In a post hoc analysis, we evaluated the impact of PMX use in patients with septic shock and endotoxin activity measured between 0.6-0.89.

METHODS

Post-hoc analysis of the EUPHRATES trial for the 194 patients with EAA ≥ 0.6-0.89 who completed two treatments (PMX or sham). The primary end point was mortality at 28 days adjusted for APACHE II score and baseline mean arterial pressure (MAP). Additional end points included changes in MAP, cumulative vasopressor index (CVI), median EAA reduction, ventilator-free days (VFD), dialysis-free days (DFD) and hospital length of stay. Subpopulations analyzed were site and type of infection and those with norepinephrine dose > 0.1 mcg/kg/min at baseline.

RESULTS

At 28 days, 23 patients of 88 (26.1%) in the PMX group died versus 39 of 106 (36.8%) in the sham group [risk difference 10.7%, OR 0.52, 95% CI (0.27, 0.99), P = 0.047]. When unadjusted for baseline variables, P = 0.11. The 28-day survival time in the PMX group was longer than for the sham group [HR 0.56 (95% CI 0.33, 0.95) P = 0.03]. PMX treatment compared with sham showed greater change in MAP [median (IQR) 8 mmHg (- 0.5, 19.5) vs. 4 mmHg (- 4.0, 11) P = 0.04] and VFD [median (IQR) 20 days (0.5, 23.5) vs. 6 days (0, 20), P = 0.004]. There were no significant differences in other end points. There was a significant difference in mortality in PMX-treated patients with no bacterial growth on culture [PMX, 6/30 (20%) vs. sham, 13/31 (41.9%), P = 0.005]. The median EAA change in the population was - 12.9% (range: increase 49.2%-reduction 86.3%). The mortality in the above median EAA change group was PMX: 6/38 (15.7%) vs. sham 15/49 (30.6%), P = 0.08.

CONCLUSIONS

These hypothesis-generating results, based on an exploratory post hoc analysis of the EUPHRATES trial, suggest measurable responses in patients with septic shock and an EAA ≥ 0.6 to 0.89 on changes in mean arterial pressure, ventilator-free days and mortality.

TRIAL REGISTRATION

Clinicaltrials.gov Identifier: NCT01046669. Funding Spectral Medical Incorporated.

Inhibition of inflammation using diacerein markedly improved renal function in endotoxemic acute kidney injured mice

BACKGROUND

Inflammation is an important pathogenic component of endotoxemia-induced acute kidney injury (AKI), finally resulting in renal failure. Diacerein is an interleukin-1β (IL-1β) inhibitor used for osteoarthritis treatment by exerting anti-inflammatory effects. This study aims to investigate the effects of diacerein on endotoxemia-induced AKI.

METHODS

Male C57BL/6 mice were intraperitoneally injected with lipopolysaccharide (LPS, 10 mg/kg) for 24 h prior to diacerein treatment (15 mg/kg/day) for another 48 h. Mice were examined by histological, molecular and biochemical approaches.

RESULTS

LPS administration showed a time-dependent increase of IL-1β expression and secretion in kidney tissues. Diacerein treatment normalized urine volume and osmolarity, reduced blood urea nitrogen (BUN), fractional excretion of sodium (FENa), serum creatinine and osmolarity, and protected renal function in an endotoxemic AKI mice model. In the histopathologic study, diacerein also improved renal tubular damage such as necrosis of the tubular segment. Moreover, diacerein inhibited LPS-induced increase of inflammatory cytokines, such as IL-1β, tumor necrosis factor-α, monocyte chemoattractant protein-1 and nitric oxide synthase 2. In addition, LPS administration markedly decreased aquaporin 1 (AQP1), AQP2, AQP3, Na,K-ATPase α1, apical type 3 Na/H exchanger and Na-K-2Cl cotransporter expression in the kidney, which was reversed by diacerein treatment. We also found that diacerein or IL-1β inhibition prevented the secretion of inflammatory cytokines and the decrease of AQP and sodium transporter expression induced by LPS in HK-2 cells.

CONCLUSION

Our study demonstrates for the first time that diacerein improves renal function efficiently in endotoxemic AKI mice by suppressing inflammation and altering tubular water and sodium handing. These results suggest that diacerein may be a novel therapeutic agent for the treatment of endotoxemic AKI.

Microbiome-Mediated Effects of the Mediterranean Diet on Inflammation

The Mediterranean diet pattern is increasingly associated with improved metabolic health. Two mechanisms by which consuming a Mediterranean diet pattern may contribute to improved metabolic health are modulation of the gastrointestinal (GI) microbiota and reduction of metabolic endotoxemia. Metabolic endotoxemia, defined as a 2- to 3-fold increase in circulating levels of bacterial endotoxin, has been proposed as a cause of inflammation during metabolic dysfunction. As the largest source of endotoxins in the human body, the GI microbiota represents a crucial area for research on strategies for reducing endotoxemia. Diets high in saturated fat and low in fiber contribute to metabolic endotoxemia through several mechanisms, including changes in the GI microbiome and bacterial fermentation end products, intestinal physiology and barrier function, and enterohepatic circulation of bile acids. Thus, the Mediterranean diet pattern, rich in unsaturated fats and fiber, may be one dietary strategy to reduce metabolic endotoxemia. Preclinical studies have demonstrated the differential effects of dietary saturated and unsaturated fats on the microbiota and metabolic health, but human studies are lacking. The role of dietary fiber and the GI microbiome in metabolic endotoxemia is underinvestigated. Clinical research on the effects of different types of dietary fat and fiber on the GI microbiota and GI and systemic inflammation is necessary to determine efficacious dietary strategies for reducing metabolic endotoxemia, inflammation, and subsequent metabolic disease.

Postprandial endotoxemia may influence the development of type 2 diabetes mellitus: From the CORDIOPREV study

BACKGROUND & AIMS

Insulin resistance (IR) and impaired beta-cell function are key determinants of type 2 diabetes mellitus (T2DM). Intestinal absorption of bacterial components activates the toll-like receptors inducing inflammation, and this in turn IR. We evaluated the role of endotoxemia in promoting inflammation-induced insulin resistance (IR) in the development of T2DM, and its usefulness as predictive biomarker.

METHODS

We included in this study 462 patients from the CORDIOPREV study without T2DM at baseline. Of these, 107 patients developed T2DM according to the American Diabetes Association (ADA) diagnosis criteria after a median follow-up of 60 months (Incident-DIAB group), whereas 355 patients did not developed it during this period of time (Non-DIAB group).

RESULTS

We observed a postprandial increase in lipopolysaccharides (LPS) levels in the Incident-DIAB at baseline (P < 0.001), whereas LPS levels were not modified in the Non-DIAB. Disease-free survival curves based on the LPS postprandial fold change improved T2DM Risk Assessment as compared with the previously described FINDRISC score (hazard ratio of 2.076, 95% CI 1.149-3.750 vs. 1.384, 95% CI 0.740-2.589). Moreover, disease-free survival curves combining the LPS postprandial fold change and FINDRISC score together showed a hazard ratio of 3.835 (95% CI 1.323-11.114), linked to high values of both parameters.

CONCLUSION

Our results suggest that a high postprandial endotoxemia precedes the development of T2DM. Our results also showed the potential use of LPS plasma levels as a biomarker predictor of T2DM development. CLINICAL TRIALS.GOV.

IDENTIFIER

NCT00924937.

Endotoxin-initiated inflammation reduces testosterone production in men of reproductive age

Inflammation, both acute and chronic, is associated with testosterone deficiency, raising the possibility of a direct causal link. One potential trigger for inflammation in obese men is the passage of intestinal bacteria into the circulation due to a breakdown in mucosal barrier integrity. Recently, we hypothesized that this endotoxin exposure may cause androgen deficiency in obese men. To test this hypothesis, we analyzed the relationship between serum levels of lipopolysaccharide-binding protein (LBP), an indirect measure of endotoxin exposure, against male reproductive hormones, inflammatory markers (C-reactive protein, IL-1β, IL-6, TNF-α), and adiposity in 75 men. Adiposity was positively correlated with endotoxin exposure (LBP) and inflammation (C-reactive protein, IL-6) and negatively correlated with testosterone. Furthermore, endotoxemia (LBP) was negatively correlated with serum testosterone but positively correlated with IL-6. Multivariate analysis revealed a significant, negative correlation between serum IL-6 and free testosterone. In a second interventional study, low-dose endotoxin challenge in lean men produced a transient inflammatory response that was followed by a decline in serum testosterone, without changes in LH or FSH, providing further evidence that endotoxin-driven inflammation may result in impaired Leydig cell function.

Muscle-derived extracellular superoxide dismutase inhibits endothelial activation and protects against multiple organ dysfunction syndrome in mice

Multiple organ dysfunction syndrome (MODS) is a detrimental clinical complication in critically ill patients with high mortality. Emerging evidence suggests that oxidative stress and endothelial activation (induced expression of adhesion molecules) of vital organ vasculatures are key, early steps in the pathogenesis. We aimed to ascertain the role and mechanism(s) of enhanced extracellular superoxide dismutase (EcSOD) expression in skeletal muscle in protection against MODS induced by endotoxemia. We showed that EcSOD overexpressed in skeletal muscle-specific transgenic mice (TG) redistributes to other peripheral organs through the circulation and enriches at the endothelium of the vasculatures. TG mice are resistant to endotoxemia (induced by lipopolysaccharide [LPS] injection) in developing MODS with significantly reduced mortality and organ damages compared with the wild type littermates (WT). Heterogenic parabiosis between TG and WT mice conferred a significant protection to WT mice, whereas mice with R213G knock-in mutation, a human single nucleotide polymorphism leading to reduced binding EcSOD in peripheral organs, exacerbated the organ damages. Mechanistically, EcSOD inhibits vascular cell adhesion molecule 1 expression and inflammatory leukocyte adhesion to the vascular wall of vital organs, blocking an early step of the pathology in organ damage under endotoxemia. Therefore, enhanced expression of EcSOD in skeletal muscle profoundly protects against MODS by inhibiting endothelial activation and inflammatory cell adhesion, which could be a promising therapy for MODS.

Lipopolysaccharide-induced endotoxemia in corn oil-preloaded mice causes an extended course of lung injury and repair and pulmonary fibrosis: A translational mouse model of acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is characterized by acute hypoxemia respiratory failure, bilateral pulmonary infiltrates, and pulmonary edema of non-cardiac origin. Effective treatments for ARDS patients may arise from experimental studies with translational mouse models of this disease that aim to delineate the mechanisms underlying the disease pathogenesis. Mouse models of ARDS, however, can be limited by their rapid progression from injured to recovery state, which is in contrast to the course of ARDS in humans. Furthermore, current mouse models of ARDS do not recapitulate certain prominent aspects of the pathogenesis of ARDS in humans. In this study, we developed an improved endotoxemic mouse model of ARDS resembling many features of clinical ARDS including extended courses of injury and recovery as well as development of fibrosis following i.p. injection of lipopolysaccharide (LPS) to corn oil-preloaded mice. Compared with mice receiving LPS alone, those receiving corn oil and LPS exhibited extended course of lung injury and repair that occurred over a period of >2 weeks instead of 3–5days. Importantly, LPS challenge of corn oil-preloaded mice resulted in pulmonary fibrosis during the repair phase as often seen in ARDS patients. In summary, this simple novel mouse model of ARDS could represent a valuable experimental tool to elucidate mechanisms that regulate lung injury and repair in ARDS patients.

The Curves Exercise Suppresses Endotoxemia in Korean Women with Obesity

Obesity and metabolic syndrome is a worldwide pandemic and associated with high cardiovascular risk. Metabolic endotoxemia (ME) is thought to be an underlying molecular mechanism. It triggers toll-like receptor 4-mediated inflammatory adipokines and causes a chronic low grade inflammatory status, which results in cardiovascular risk increase. Exercise is the best nonpharmacological treatment to improve prognosis. In this study, we examined the circulating endotoxin level in Korean obese women and investigated effects of exercise on it. Women over body mass index (BMI) 25 kg/m² participated in a resistance training exercise, Curves. At baseline and after 12 weeks exercise, tests including blood samples were taken. In Korean obese women, the fasting endotoxin was 1.45 ± 0.11 EU/mL. Ingestion of a high calorie meal led to a peak level after 2 hours (postprandial 2 hours [PP2]) and a significant rise over the 4 hours (postprandial 4 hours [PP4]) in it (1.78 ± 0.15 and 1.75 ± 0.14 EU/mL for PP2 and PP4, P < 0.05 vs. fasting). After exercise, BMI and hip circumference were reduced significantly. The total cholesterol (TC) at fasting, PP2 and PP4 were decreased significantly. All levels of circulating endotoxin at fasting, PP2 and PP4 showed reduction. But, the peak change was only significant (baseline vs. 12 weeks for PP2; 1.78 ± 0.15 vs. 1.48 ± 0.06 EU/mL, P < 0.05). We report the circulating endotoxin level in Korean obese women for the first time. Also, we establish that energy intake leads to endotoxemia and exercise suppresses the peak endotoxemia after meal. It suggests an impact for a better prognosis in obese women who follow regular exercise.

Effect of Physical Exercise on the Febrigenic Signaling is Modulated by Preoptic Hydrogen Sulfide Production

We tested the hypothesis that the neuromodulator hydrogen sulfide (H₂S) in the preoptic area (POA) of the hypothalamus modulates the febrigenic signaling differently in sedentary and trained rats. Besides H₂S production rate and protein expressions of H₂S-related synthases cystathionine β-synthase (CBS), 3-mercaptopyruvate sulfurtransferase (3-MPST) and cystathionine γ-lyase (CSE) in the POA, we also measured deep body temperature (Tb), circulating plasma levels of cytokines and corticosterone in an animal model of systemic inflammation. Rats run on a treadmill before receiving an intraperitoneal injection of lipopolysaccharide (LPS, 100 μg/kg) or saline. The magnitude of changes of Tb during the LPS-induced fever was found to be similar between sedentary and trained rats. In sedentary rats, H₂S production was not affected by LPS. Conversely, in trained rats LPS caused a sharp increase in H₂S production rate that was accompanied by an increased CBS expression profile, whereas 3-MPST and CSE expressions were kept relatively constant. Sedentary rats showed a significant LPS-induced release of cytokines (IL-1β, IL-6, and TNF-α) which was virtually abolished in the trained animals. Correlation between POA H₂S and IL-6 as well as TNF-α was observed. Corticosterone levels were augmented after LPS injection in both groups. We found correlations between H₂S and corticosterone, and corticosterone and IL-1β. These data are consistent with the notion that the responses to systemic inflammation are tightly regulated through adjustments in POA H₂S production which may play an anti-inflammatory role downmodulating plasma cytokines levels and upregulating corticosterone release.

Resveratrol alleviates endotoxemia-associated adrenal insufficiency by suppressing oxidative/nitrative stress

We have recently demonstrated that endotoxin causes oxidative stress and overproduction of nitric oxide in adrenal glands, thereby leading to adrenocortical insufficiency. The aim of this study is to investigate the effects of resveratrol, a natural plant polyphenol with anti-oxidant and anti-nitrative properties, on endotoxemia-associated adrenocortical insufficiency. Resveratrol was administered immediately before injection of lipopolysaccharide (LPS). Twenty four hours later, the adrenocorticotropic hormone (ACTH) stimulation tests was been performed to measure the plasma corticosterone level and the adrenal gland tissues were collected for histopathologic examination, and determination of malondialdehyde (MDA), total antioxidant capacity (T-AOC), superoxide dismutase (SOD) activity, catalase (CAT) activity, inducible nitric oxide synthase (iNOS) expression, nitric oxide (NO) and peroxynitrite production. Treatment with resveratrol significantly inhibited endotoxemia-induced iNOS expression, NO production, and peroxynitrite formation and also attenuated LPS-induced oxidative stress in the adrenal gland, as evidenced by the decrease of pro-oxidant biomarker (MDA), and the increases of anti-oxidant biomarkers (T-AOC, CAT and SOD activity). H&E staining demonstrated that administration of LPS resulted in increased into the adrenal gland. H&E-stained sections of adrenal glands demonstrated signs of leukocyte infiltration and hemorrhage during endotoxemia, which were significantly improved by resveratrol treatment. In addition, resveratrol reversed the LPS-induced downregulation of ACTH receptor and silent information regulator 1 (SIRT1) in adrenal gland, as well as adrenocortical hyporesponsiveness to ACTH. Resveratrol exerts protective effects against endotoxemia-associated adrenocortical insufficiency by suppressing oxidative/nitrative stress. These findings support the potential for resveratrol as a possible pharmacological agent to improve adrenocortical insufficiency resulting from oxidative/nitrative damage.

Reparixin, a Specific Interleukin-8 Inhibitor, Has No Effects on Inflammation during Endotoxemia

Reparixin antagonizes interleukin-8 (IL-8) on the level of signal transduction in vitro. We hypothesized that IL-8 mediates some of the reactions occurring during acute inflammation and specifically that IL-8 may be a mediator of endotoxin induced neutrophilia. We therefore tested the effects of reparixin on humoral and cellular parameters in LPS-induced acute systemic inflammation. The study is a randomized (3:2 active:placebo), double-blind, placebo-controlled parallel group trial. Twenty healthy male volunteers randomly received either reparixin (12) or placebo (8) intravenously. One hour after the start of reparixin/placebo infusion a bolus of 2 ng/kg endotoxin was infused over 1–2 min. Blood samples were obtained over 24 h. Reparixin, being metabolized to ibuprofen, suppressed serum thromboxane B2 levels by 78% compared to baseline and control at 8 h. LPS-induced neutrophilia was not significantly affected by reparixin in human volunteers. Consistently, reparixin did not alter the lymphocyte or monocyte counts and had no effect on LPS-induced systemic inflammation as measured by tumor necrosis factor alpha (TNF-α) or interleukin-6 (IL-6) release. Regulation of IL-8 receptors CXCR1 and 2 and the degranulation marker CD11b showed the expected kinetics. Reparixin had no effect on thrombin formation as measured by prothrombin fragment (F1+2). In conclusion, our study showed that reparixin was safe but had no impact on endotoxin induced inflammation. In contrast to previous studies with its metabolite ibuprofen, reparixin does not enhance inflammation in this model.

Autophagy Limits Endotoxemic Acute Kidney Injury and Alters Renal Tubular Epithelial Cell Cytokine Expression

Sepsis related acute kidney injury (AKI) is a common in-hospital complication with a dismal prognosis. Our incomplete understanding of disease pathogenesis has prevented the identification of hypothesis-driven preventive or therapeutic interventions. Increasing evidence in ischemia-reperfusion and nephrotoxic mouse models of AKI support the theory that autophagy protects renal tubular epithelial cells (RTEC) from injury. However, the role of RTEC autophagy in septic AKI remains unclear. We observed that lipopolysaccharide (LPS), a mediator of gram-negative bacterial sepsis, induces RTEC autophagy in vivo and in vitro through TLR4-initiated signaling. We modeled septic AKI through intraperitoneal LPS injection in mice in which autophagy-related protein 7 was specifically knocked out in the renal proximal tubules (ATG7KO). Compared to control littermates, ATG7KO mice developed more severe renal dysfunction (24hr BUN 100.1mg/dl +/- 14.8 vs 54.6mg/dl +/- 11.3) and parenchymal injury. After injection with LPS, analysis of kidney lysates identified higher IL-6 expression and increased STAT3 activation in kidney lysates from ATG7KO mice compared to controls. In vitro experiments confirmed an altered response to LPS in RTEC with genetic or pharmacological impairment of autophagy. In conclusion, RTEC autophagy protects against endotoxin induced injury and regulates downstream effects of RTEC TLR4 signaling.

Therapeutic Effects of Procainamide on Endotoxin-Induced Rhabdomyolysis in Rats

Overt systemic inflammatory response is a predisposing mechanism for infection-induced skeletal muscle damage and rhabdomyolysis. Aberrant DNA methylation plays a crucial role in the pathophysiology of excessive inflammatory response. The antiarrhythmic drug procainamide is a non-nucleoside inhibitor of DNA methyltransferase 1 (DNMT1) used to alleviate DNA hypermethylation. Therefore, we evaluated the effects of procainamide on the syndromes and complications of rhabdomyolysis rats induced by lipopolysaccharide (LPS). Rhabdomyolysis animal model was established by intravenous infusion of LPS (5 mg/kg) accompanied by procainamide therapy (50 mg/kg). During the experimental period, the changes of hemodynamics, muscle injury index, kidney function, blood gas, blood electrolytes, blood glucose, and plasma interleukin-6 (IL-6) levels were examined. Kidneys and lungs were exercised to analyze superoxide production, neutrophil infiltration, and DNMTs expression. The rats in this model showed similar clinical syndromes and complications of rhabdomyolysis including high levels of plasma creatine kinase, acute kidney injury, hyperkalemia, hypocalcemia, metabolic acidosis, hypotension, tachycardia, and hypoglycemia. The increases of lung DNMT1 expression and plasma IL-6 concentration were also observed in rhabdomyolysis animals induced by LPS. Treatment with procainamide not only inhibited the overexpression of DNMT1 but also diminished the overproduction of IL-6 in rhabdomyolysis rats. In addition, procainamide improved muscle damage, renal dysfunction, electrolytes disturbance, metabolic acidosis, hypotension, and hypoglycemia in the rats with rhabdomyolysis. Moreover, another DNMT inhibitor hydralazine mitigated hypoglycemia, muscle damage, and renal dysfunction in rhabdomyolysis rats. These findings reveal that therapeutic effects of procainamide could be based on the suppression of DNMT1 and pro-inflammatory cytokine in endotoxin-induced rhabdomyolysis.

Permissive role of AMPK and autophagy in adiponectin deficiency-accentuated myocardial injury and inflammation in endotoxemia

BACKGROUND

Adiponectin (APN), an adipose-derived adipokine, alleviates lipopolysaccharide (LPS)-induced injury in multiple organs including hearts although the underlying mechanism in endotoxemia remains elusive. This study was designed to examine the role of adiponectin in LPS-induced cardiac anomalies and inflammation as well as the underlying mechanism with a focus on autophagy - a conserved machinery for bulk degradation of intracellular components.

METHODS AND RESULTS

Wild-type (WT) and APN(-/-) mice were challenged with LPS (4mg/kg) or saline for 6h. Echocardiography, cardiomyocyte contractile and intracellular Ca(2+) properties were evaluated. Markers of autophagy, apoptosis and inflammation including LC3B, p62, Beclin1, AMPK, mTOR, ULK, Caspase 3, Bcl-2, Bax, TLR4, TRAF6, MyD88, IL-1B, TNFα, HMGB1, JNK and IκB were examined using Western blot or RT-PCR. Our results showed that LPS challenge reduced fractional shortening, compromised cardiomyocyte contractile capacity, intracellular Ca(2+) handling properties, apoptosis and inflammation, which were accentuated by adiponectin ablation. Adiponectin ablation unmasked the LPS-induced cardiac remodeling (left ventricular end systolic diameter) and prolongation of cell shortening. The detrimental effects of adiponectin ablation were associated with dampened autophagy in response to LPS through an AMPK-mTOR-ULK1-dependent mechanism. In vivo administration of AMPK activator AICAR or the autophagy inducer rapamycin effectively attenuated or obliterated LPS-induced and adiponectin deficiency-accentuated responses without affecting TLR4, TRAF6 and MyD88.

CONCLUSIONS

The findings suggest that AMPK and autophagy may play a permissive role in the adiponectin deficiency-exacerbated cardiac dysfunction, apoptosis and inflammation under LPS challenge possibly at the post-TLR4 receptor level.