Growth Arrest-Specific Gene 6 Administration Ameliorates Sepsis-Induced Organ Damage in Mice and Reduces ROS Formation In Vitro.
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ABSTRACT:
SUBMITTER: Salmi L
PROVIDER: S-EPMC7998241 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Sepsis is a life-threatening acute inflammatory condition associated with metabolic complications. Accumulation of free fatty acids (FFAs) induces inflammation and causes lipotoxic effects in the liver. Because fatty acid metabolism plays a role in the inflammatory response, we hypothesized that the administration of C75, a fatty acid synthase inhibitor, could alleviate the injury caused by sepsis.Male mice were subjected to sepsis by cecal ligation and puncture (CLP). At 4 h after CLP, different doses of C75 (1- or 5-mg/kg body weight) or vehicle (20% dimethyl sulfoxide in saline) were injected intraperitoneally. Blood and liver tissues were collected at 24 h after CLP.C75 treatment with 1- and 5-mg/kg body weight significantly lowered FFA levels in the liver after CLP by 28% and 53%, respectively. Administration of C75 dose dependently reduced serum indexes of organ injury (aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase) and serum levels of tumor necrosis factor alpha (TNF-?) and interleukin 6 (IL-6). In the liver, C75 treatment reduced inflammation (TNF-? and IL-6) and oxidative stress (inducible nitric oxide synthase and cyclooxygenase 2) in a dose-dependent manner. The 5-mg dose improved the 10-d survival rate to 85% from that of 55% in the vehicle. In the presence of C75, TNF-? release in RAW 246.7 cells with 4-h lipopolysaccharide stimulation was also significantly reduced.C75 effectively lowered FFA accumulation in the liver, which was associated with inhibition of inflammation and organ injury as well as improvement in survival rate after CLP. Thus, inhibition of FFA by C75 could ameliorate the hepatic dysfunction seen in sepsis.
| S-EPMC4688159 | biostudies-literature
Project description:Liver kinase B1 (LKB1, also known as serine/threonine kinase 11, STK11) is a tumor suppressor mutated in Peutz-Jeghers syndrome and in a variety of sporadic cancers. Herein, we demonstrate that LKB1 controls the levels of intracellular reactive oxygen species (ROS) and protects the genome from oxidative damage. Cells lacking LKB1 exhibit markedly increased intracellular ROS levels, excessive oxidation of DNA, increased mutation rates and accumulation of DNA damage, which are effectively prevented by ectopic expression of LKB1 and by incubation with antioxidant N-acetylcysteine. The role of LKB1 in suppressing ROS is independent of AMP-activated protein kinase, a canonical substrate of LKB1. Instead, under the elevated ROS, LKB1 binds to and maintains the activity of the cdc42-PAK1 (p21-activated kinase 1) complex, which triggers the activation of p38 and its downstream signaling targets, such as ATF-2, thereby enhancing the activity of superoxide dismutase-2 and catalase, two antioxidant enzymes that protect the cells from ROS accumulation, DNA damage and loss of viability. Our results provide a new paradigm for a non-canonical tumor suppressor function of LKB1 and highlight the importance of targeting ROS signaling as a potential therapeutic strategy for cancer cells lacking LKB1.
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Project description:OBJECTIVES:The physiology of nearly all mammalian organisms are entrained by light and exhibit circadian rhythm. The data derived from animal studies show that light influences immunity, and these neurophysiologic pathways are maximally entrained by the blue spectrum. Here, we hypothesize that bright blue light reduces acute kidney injury by comparison with either bright red or standard, white fluorescent light in mice subjected to sepsis. To further translational relevance, we performed a pilot clinical trial of blue light therapy in human subjects with appendicitis. DESIGN:Laboratory animal research, pilot human feasibility trial. SETTING:University basic science laboratory and tertiary care hospital. SUBJECTS:Male C57BL/6J mice, adult (> 17 yr) patients with acute appendicitis. INTERVENTIONS:Mice underwent cecal ligation and puncture and were randomly assigned to a 24-hour photoperiod of bright blue, bright red, or ambient white fluorescent light. Subjects with appendicitis were randomized to receive postoperatively standard care or standard care plus high-illuminance blue light. MEASUREMENTS AND MAIN RESULTS:Exposure to bright blue light enhanced bacterial clearance from the peritoneum, reduced bacteremia and systemic inflammation, and attenuated the degree of acute kidney injury. The mechanism involved an elevation in cholinergic tone that augmented tissue expression of the nuclear orphan receptor REV-ERB? and occurred independent of alterations in melatonin or corticosterone concentrations. Clinically, exposure to blue light after appendectomy was feasible and reduced serum interleukin-6 and interleukin-10 concentrations. CONCLUSIONS:Modifying the spectrum of light may offer therapeutic utility in sepsis.
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Project description:Prolonged muscle exposure to low PO2 conditions may cause oxidative stress resulting in severe muscular injuries. We hypothesize that PO2 cycling preconditioning, which involves brief cycles of diaphragmatic muscle exposure to a low oxygen level (40 Torr) followed by a high oxygen level (550 Torr), can reduce intracellular reactive oxygen species (ROS) as well as attenuate muscle fatigue in mouse diaphragm under low PO2. Accordingly, dihydrofluorescein (a fluorescent probe) was used to monitor muscular ROS production in real time with confocal microscopy during a lower PO2 condition. In the control group with no PO2 cycling, intracellular ROS formation did not appear during the first 15 min of the low PO2 period. However, after 20 min of low PO2, ROS levels increased significantly by ?30% compared to baseline, and this increase continued until the end of the 30 min low PO2 condition. Conversely, muscles treated with PO2 cycling showed a complete absence of enhanced fluorescence emission throughout the entire low PO2 period. Furthermore, PO2 cycling-treated diaphragm exhibited increased fatigue resistance during prolonged low PO2 period compared to control. Thus, our data suggest that PO2 cycling mitigates diaphragm fatigue during prolonged low PO2. Although the exact mechanism for this protection remains to be elucidated, it is likely that through limiting excessive ROS levels, PO2 cycling initiates ROS-related antioxidant defenses.
| S-EPMC4192541 | biostudies-literature
Project description:AIMS:Sepsis-caused multiple organ failure remains the major cause of morbidity and mortality in intensive care units. Nicotinamide riboside (NR) is a precursor of nicotinamide adenine dinucleotide (NAD+), which is important in regulating oxidative stress. This study investigated whether administration of NR prevented oxidative stress and organ injury in sepsis. METHODS:Mouse sepsis models were induced by injection of lipopolysaccharides (LPS) or feces-injection-in-peritoneum. NR was given before sepsis onset. Cultured macrophages and endothelial cells were incubated with various agents. RESULTS:Administration of NR elevated the NAD+ levels, and elicited a reduction of oxidative stress, inflammation and caspase-3 activity in lung and heart tissues, which correlated with attenuation of pulmonary microvascular permeability and myocardial dysfunction, leading to less mortality in sepsis models. These protective effects of NR were associated with decreased levels of plasma high mobility group box-1 (HMGB1) in septic mice. Consistently, pre-treatment of macrophages with NR increased NAD+ content and reduced HMGB1 release upon LPS stimulation. NR also prevented reactive oxygen species (ROS) production and apoptosis in endothelial cells induced by a conditioned-medium collected from LPS-treated macrophages. Furthermore, inhibition of SIRT1 by EX527 offset the negative effects of NR on HMGB1 release in macrophages, and ROS and apoptosis in endothelial cells. CONCLUSIONS:Administration of NR prevents lung and heart injury, and improves the survival in sepsis, likely by inhibiting HMGB1 release and oxidative stress via the NAD+/SIRT1 signaling. Given NR has been used as a health supplement, it may be a useful agent to prevent organ injury in sepsis.
| S-EPMC6236680 | biostudies-literature
Project description:Organ dysfunction is a major concern in sepsis pathophysiology and contributes to its high mortality rate. Neutrophil extracellular traps (NETs) have been implicated in endothelial damage and take part in the pathogenesis of organ dysfunction in several conditions. NETs also have an important role in counteracting invading microorganisms during infection. The aim of this study was to evaluate systemic NETs formation, their participation in host bacterial clearance and their contribution to organ dysfunction in sepsis. C57Bl/6 mice were subjected to endotoxic shock or a polymicrobial sepsis model induced by cecal ligation and puncture (CLP). The involvement of cf-DNA/NETs in the physiopathology of sepsis was evaluated through NETs degradation by rhDNase. This treatment was also associated with a broad-spectrum antibiotic treatment (ertapenem) in mice after CLP. CLP or endotoxin administration induced a significant increase in the serum concentrations of NETs. The increase in CLP-induced NETs was sustained over a period of 3 to 24 h after surgery in mice and was not inhibited by the antibiotic treatment. Systemic rhDNase treatment reduced serum NETs and increased the bacterial load in non-antibiotic-treated septic mice. rhDNase plus antibiotics attenuated sepsis-induced organ damage and improved the survival rate. The correlation between the presence of NETs in peripheral blood and organ dysfunction was evaluated in 31 septic patients. Higher cf-DNA concentrations were detected in septic patients in comparison with healthy controls, and levels were correlated with sepsis severity and organ dysfunction. In conclusion, cf-DNA/NETs are formed during sepsis and are associated with sepsis severity. In the experimental setting, the degradation of NETs by rhDNase attenuates organ damage only when combined with antibiotics, confirming that NETs take part in sepsis pathogenesis. Altogether, our results suggest that NETs are important for host bacterial control and are relevant actors in the pathogenesis of sepsis.
| S-EPMC4743982 | biostudies-literature
Project description:Recent clinical trials indicate that probiotic administration in critical illness has potential to reduce nosocomial infections and improve clinical outcome. However, the mechanism(s) of probiotic-mediated protection against infection and sepsis remain elusive. The authors evaluated the effects of Lactobacillus rhamnosus GG (LGG) and Bifidobacterium longum (BL) on mortality, bacterial translocation, intestinal epithelial homeostasis, and inflammatory response in experimental model of septic peritonitis.Cecal ligation and puncture (n=14 per group) or sham laparotomy (n=8 per group) were performed on 3-week-old FVB/N weanling mice treated concomitantly with LGG, BL, or vehicle (orally gavaged). At 24 h, blood and colonic tissue were collected. In survival studies, mice were given probiotics every 24 h for 7 days (LGG, n=14; BL, n=10; or vehicle, n=13; shams, n=3 per group).Probiotics significantly improved mortality after sepsis (92 vs. 57% mortality for LGG and 92 vs. 50% mortality for BL; P=0.003). Bacteremia was markedly reduced in septic mice treated with either probiotic compared with vehicle treatment (4.39±0.56 vs. 1.07±1.54; P=0.0001 for LGG; vs. 2.70±1.89; P=0.016 for BL; data are expressed as mean±SD). Sepsis in untreated mice increased colonic apoptosis and reduced colonic proliferation. Probiotics significantly reduced markers of colonic apoptosis and returned colonic proliferation to sham levels. Probiotics led to significant reductions in systemic and colonic inflammatory cytokine expression versus septic animals. Our data suggest that involvement of the protein kinase B pathway (via AKT) and down-regulation of Toll-like receptor 2/Toll-like receptor 4 via MyD88 in the colon may play mechanistic roles in the observed probiotic benefits.Our data demonstrate that probiotic administration at initiation of sepsis can improve survival in pediatric experimental sepsis. The mechanism of this protection involves prevention of systemic bacteremia, perhaps via improved intestinal epithelial homeostasis, and attenuation of the local and systemic inflammatory responses.
| S-EPMC5545110 | biostudies-other
Project description:Background and purposeThere is increasing evidence that potassium channels are involved in the cardiovascular dysfunction of sepsis. This evidence was obtained after the systemic inflammation, cardiovascular dysfunction and organ damage had developed. Here we have studied the consequences of early interference with potassium channels on development of sepsis.Experimental approachSepsis was induced by caecal ligation and puncture (CLP) or sham surgery in Wistar rats. Four hours after surgery, animals received tetraethylammonium (TEA; a non-selective potassium channel blocker) or glibenclamide (a selective ATP-sensitive potassium channel blocker). Twenty-four hours after surgery, inflammatory, biochemical, haemodynamic parameters and survival were evaluated.Key resultsSepsis significantly increased plasma NO(x) levels, expression of inducible nitric oxide synthase (NOS-2) protein in lung and thigh skeletal muscle, lung myeloperoxidase, urea, creatinine and lactate levels, TNF-? and IL-1?, hypotension and hyporesponsiveness to phenylephrine and hyperglycemia followed by hypoglycemia. TEA injected 4?h after surgery attenuated the increased NOS-2 expression, reduced plasma NO(x) , lung myeloperoxidase activity, levels of TNF-? and IL-1?, urea, creatinine and lactate levels, prevented development of hypotension and hyporesponsiveness to phenylephrine, the alterations in plasma glucose and reduced late mortality by 50%. Glibenclamide did not improve any of the measured parameters and increased mortality rate, probably due to worsening the hypoglycemic phase of sepsis.Conclusions and implicationsEarly blockade of TEA-sensitive (but not the ATP-sensitive subtype) potassium channels reduced organ damage and mortality in experimental sepsis. This beneficial effect seems to be, at least in part, due to reduction in NOS-2 expression.
| S-EPMC3144541 | biostudies-literature
Project description:S100A9, a pro-inflammatory alarmin, is up-regulated in inflamed tissues. However, the role of S100A9 in regulating neutrophil activation, inflammation and lung damage in sepsis is not known. Herein, we hypothesized that blocking S100A9 function may attenuate neutrophil recruitment in septic lung injury. Male C57BL/6 mice were pretreated with the S100A9 inhibitor ABR-238901 (10 mg/kg), prior to cercal ligation and puncture (CLP). Bronchoalveolar lavage fluid (BALF) and lung tissue were harvested for analysis of neutrophil infiltration as well as edema and CXC chemokine production. Blood was collected for analysis of membrane-activated complex-1 (Mac-1) expression on neutrophils as well as CXC chemokines and IL-6 in plasma. Induction of CLP markedly increased plasma levels of S100A9. ABR-238901 decreased CLP-induced neutrophil infiltration and edema formation in the lung. In addition, inhibition of S100A9 decreased the CLP-induced up-regulation of Mac-1 on neutrophils. Administration of ABR-238901 also inhibited the CLP-induced increase of CXCL-1, CXCL-2 and IL-6 in plasma and lungs. Our results suggest that S100A9 promotes neutrophil activation and pulmonary accumulation in sepsis. Targeting S100A9 function decreased formation of CXC chemokines in circulation and lungs and attenuated sepsis-induced lung damage. These novel findings suggest that S100A9 plays an important pro-inflammatory role in sepsis and could be a useful target to protect against the excessive inflammation and lung damage associated with the disease.
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Project description:As extracellular vesicles that play an active role in intercellular communication by transferring cellular materials to recipient cells, exosomes offer great potential as a natural therapeutic drug delivery vehicle. The inflammatory responses in various disease models can be attenuated through introduction of super-repressor IκB (srIκB), which is the dominant active form of IκBα and can inhibit translocation of nuclear factor κB into the nucleus. An optogenetically engineered exosome system (EXPLOR) that we previously developed was implemented for loading a large amount of srIκB into exosomes. We showed that intraperitoneal injection of purified srIκB-loaded exosomes (Exo-srIκBs) attenuates mortality and systemic inflammation in septic mouse models. In a biodistribution study, Exo-srIκBs were observed mainly in the neutrophils, and in monocytes to a lesser extent, in the spleens and livers of mice. Moreover, we found that Exo-srIκB alleviates inflammatory responses in monocytic THP-1 cells and human umbilical vein endothelial cells.
| S-EPMC7141819 | biostudies-literature