Opposing Effects of Fasting Metabolism on Tissue Tolerance in Bacterial and Viral Inflammation.

Acute infections are associated with a set of stereotypic behavioral responses, including anorexia, lethargy, and social withdrawal. Although these so-called sickness behaviors are the most common and familiar symptoms of infections, their roles in host defense are largely unknown. Here, we investigated the role of anorexia in models of bacterial and viral infections. We found that anorexia was protective while nutritional supplementation was detrimental in bacterial sepsis. Furthermore, glucose was necessary and sufficient for these effects. In contrast, nutritional supplementation protected against mortality from influenza infection and viral sepsis, whereas blocking glucose utilization was lethal. In both bacterial and viral models, these effects were largely independent of pathogen load and magnitude of inflammation. Instead, we identify opposing metabolic requirements tied to cellular stress adaptations critical for tolerance of differential inflammatory states. VIDEO ABSTRACT.

The kinase Jnk2 promotes stress-induced mitophagy by targeting the small mitochondrial form of the tumor suppressor ARF for degradation.

Mitophagy is essential for cellular homeostasis, but how mitophagy is regulated is largely unknown. Here we found that the kinase Jnk2 was required for stress-induced mitophagy. Jnk2 promoted ubiquitination and proteasomal degradation of the small mitochondrial form of the tumor suppressor ARF (smARF). Loss of Jnk2 led to the accumulation of smARF, which induced excessive autophagy that resulted in lysosomal degradation of the mitophagy adaptor p62 at steady state. Depletion of p62 prevented Jnk2-deficient cells from mounting mitophagy upon stress. Jnk2-deficient mice displayed defective mitophagy, which resulted in tissue damage under hypoxic stress, as well as hyperactivation of inflammasomes and increased mortality in sepsis. Our findings define a unique mechanism of maintaining immunological homeostasis that protects the host from tissue damage and mortality.

Lipopolysaccharide-induced sepsis impairs M2R-GIRK signaling in the mouse sinoatrial node.

Sepsis has emerged as a global health burden associated with multiple organ dysfunction and 20% mortality rate in patients. Numerous clinical studies over the past two decades have correlated the disease severity and mortality in septic patients with impaired heart rate variability (HRV), as a consequence of impaired chronotropic response of sinoatrial node (SAN) pacemaker activity to vagal/parasympathetic stimulation. However, the molecular mechanism(s) downstream to parasympathetic inputs have not been investigated yet in sepsis, particularly in the SAN. Based on electrocardiography, fluorescence Ca2+ imaging, electrophysiology, and protein assays from organ to subcellular level, we report that impaired muscarinic receptor subtype 2-G protein-activated inwardly-rectifying potassium channel (M2R-GIRK) signaling in a lipopolysaccharide-induced proxy septic mouse model plays a critical role in SAN pacemaking and HRV. The parasympathetic responses to a muscarinic agonist, namely IKACh activation in SAN cells, reduction in Ca2+ mobilization of SAN tissues, lowering of heart rate and increase in HRV, were profoundly attenuated upon lipopolysaccharide-induced sepsis. These functional alterations manifested as a direct consequence of reduced expression of key ion-channel components (GIRK1, GIRK4, and M2R) in the mouse SAN tissues and cells, which was further evident in the human right atrial appendages of septic patients and likely not mediated by the common proinflammatory cytokines elevated in sepsis.

Resolvin D2 attenuates LPS-induced macrophage exhaustion.

Early in sepsis, a hyperinflammatory response is dominant, but later, an immunosuppressive phase dominates, and the host is susceptible to opportunistic infections. Anti-inflammatory agents may accelerate the host into immunosuppression, and few agents can reverse immunosuppression without causing inflammation. Specialized pro-resolving mediators (SPMs) such as resolvin D2 (RvD2) have been reported to resolve inflammation without being immunosuppressive, but little work has been conducted to examine their effects on immunosuppression. To assess the effects of RvD2 on immunosuppression, we established a model of macrophage exhaustion using two lipopolysaccharide (LPS) treatments or hits. THP-1 monocyte-derived macrophages were first treated with RvD2 or vehicle for 1 h. One LPS hit increased NF-κB activity 11-fold and TNF-α release 60-fold compared to unstimulated macrophages. RvD2 decreased LPS-induced NF-κB activity and TNF-α production but increased bacterial clearance. Two LPS hits reduced macrophage bacterial clearance and decreased macrophage NF-κB activity (45%) and TNF-α release (75%) compared to one LPS hit, demonstrating exhaustion. RvD2 increased NF-κB activity, TNF-α release, and bacterial clearance following two LPS hits compared to controls. TLR2 inhibition abolished RvD2-mediated changes. In a mouse sepsis model, splenic macrophage response to exogenous LPS was reduced compared to controls and was restored by in vivo administration of RvD2, supporting the in vitro results. If RvD2 was added to monocytes before differentiation into macrophages, however, RvD2 reduced LPS responses and increased bacterial clearance following both one and two LPS hits. The results show that RvD2 attenuated macrophage suppression in vitro and in vivo and that this effect was macrophage-specific.

ANGPTL8 deficiency attenuates lipopolysaccharide-induced liver injury by improving lipid metabolic dysregulation.

Liver injury is closely related to poor outcomes in sepsis patients. Current studies indicate that sepsis is accompanied by metabolic disorders, especially those related to lipid metabolism. It is highly important to explore the mechanism of abnormal liver lipid metabolism during sepsis. As a key regulator of glucose and lipid metabolism, angiopoietin-like 8 (ANGPTL8) is involved in the regulation of multiple chronic metabolic diseases. In the present study, severe liver lipid deposition and lipid peroxidation were observed in the early stages of lipopolysaccharide (LPS) induced liver injury. LPS promotes the expression of ANGPTL8 both in vivo and in vitro. Knockout of Angptl8 reduced hepatic lipid accumulation and lipid peroxidation, improved fatty acid oxidation and liver function, and increased the survival rate of septic mice by activating the PGC1α/PPARα pathway. We also found that the expression of ANGPTL8 induced by LPS depends on TNF-α, and that inhibiting the TNF-α pathway reduces LPS-induced hepatic lipid deposition and lipid peroxidation. However, knocking out Angptl8 improved the survival rate of septic mice better than inhibiting the TNF-α pathway. Taken together, the results of our study suggest that ANGPTL8 functions as a novel cytokine in LPS-induced liver injury by suppressing the PGC1α/PPARα signaling pathway. Therefore, targeting ANGPTL8 to improve liver lipid metabolism represents an attractive strategy for the management of sepsis patients.

Sepsis induced cardiotoxicity by promoting cardiomyocyte cuproptosis.

BACKGROUND: Currently, sepsis induced cardiotoxicity is among the major causes of sepsis-related death. The specific molecular mechanisms of sepsis induced cardiotoxicity are currently unknown. Therefore, the purpose of this paper is to identify the key molecule mechanisms for sepsis induced cardiotoxicity. METHODS: Original data of sepsis induced cardiotoxicity was derived from Gene Expression Omnibus (GEO; GSE63920; GSE44363; GSE159309) dataset. Functional enrichment analysis was used to analysis sepsis induced cardiotoxicity related signaling pathways. Our findings also have explored the relationship of cuproptosis and N6-Methyladenosine (m6A) in sepsis induced cardiotoxicity. Mice are randomly assigned to 3 groups: saline treatment control group, LPS group administered a single 5 mg/kg dose of LPS for 24 h, LPS + CD274 inhibitor group administered 10 mg/kg CD274 inhibitor for 24 h. RESULTS: Overall, expression of cuproptosis-related genes (CRGs) CD274, Ceruloplasmin (CP), Vascular endothelial growth factor A (VEGFA), Copper chaperone for cytochrome c oxidase 11 (COX11), chemokine C-C motif ligand 8 (CCL8), Mitogen-activated protein kinase kinase 1(MAP2K1), Amine oxidase 3 (AOC3) were significantly altered in sepsis induced cardiotoxicity. The results of spearman correlation analysis was significant relationship between differentially regulated genes (DEGs) of CRGs and the expression level of m6A methylation genes. GO and KEGG showed that these genes were enriched in response to interferon-beta, MHC class I peptide loading complex, proteasome core complex, chemokine receptor binding, TAP binding, chemokine activity, cytokine activity and many more. These findings suggest that cuproptosis is strongly associated with sepsis induced cardiotoxicity. CONCLUSION: In the present study, we found that cuproptosis were associated with sepsis induced cardiotoxicity. The CD274, CP, VEGFA, COX11, CCL8, MAP2K1, AOC3 genes are showing a significant difference expression in sepsis induced cardiotoxicity. Our studies have found significant correlations between CRGs and m6A methylation related genes in sepsis induced cardiotoxicity. These results provide insight into mechanism for sepsis induced cardiotoxicity.

m6A-mediated upregulation of miRNA-193a aggravates cardiomyocyte apoptosis and inflammatory response in sepsis-induced cardiomyopathy via the METTL3/ miRNA-193a/BCL2L2 pathway.

The impact of N6-methyladenosine (m6A) modification on pri-miRNA in sepsis-induced cardiomyopathy (SICM), and its underlying regulatory mechanism, have not been fully elucidated. We successfully constructed a SICM mice model through cecal ligation and puncture (CLP). In vitro, a lipopolysaccharide (LPS)-induced HL-1 cells model was also established. The results showed that sepsis frequently resulted in excessive inflammatory response concomitant with impaired myocardial function in mice exposed to CLP, as indicated by decreases in ejection fraction (EF), fraction shortening (FS), and left ventricular end diastolic diameters (LVDd). miR-193a was enriched in CLP mice heart and in LPS-treated HL-1 cells, while overexpression of miR-193a significantly increased the expression levels of cytokines. Sepsis-induced enrichment of miR-193a significantly inhibited cardiomyocytes proliferation and enhanced apoptosis, while this was reversed by miR-193a knockdown. Furthermore, under our experimental conditions, enrichment of miR-193a in SICM could be considered excessively maturated on pri-miR-193a by enhanced m6A modification. This modification was catalyzed by sepsis-induced overexpression of methyltransferase-like 3 (METTL3). Moreover, mature miRNA-193a bound to a predictive sequence within 3'UTRs of a downstream target, BCL2L2, which was further validated by the observation that the BCL2L2-3'UTR mutant failed to decrease luciferase activity when co-transfected with miRNA-193a. The interaction between miRNA-193a and BCL2L2 resulted in BCL2L2 downregulation, subsequently activating the caspase-3 apoptotic pathway. In conclusion, sepsis-induced miR-193a enrichment via m6A modification plays an essential regulatory role in cardiomyocyte apoptosis and inflammatory response in SICM. The detrimental axis of METTL3/m6A/miR-193a/BCL2L2 is implicated in the development of SICM.

The effect of thyme essential oil and endothelial progenitor stem cells on lipopolysaccharide-induced sepsis in C57BL/6 mice.

Sepsis is a potentially fatal syndrome related to severe systemic inflammation developed by infection. Despite different antimicrobial therapies, morbidity and mortality rates remain high. Herbs along with cell therapy have been introduced as a promising option to improve the symptoms of sepsis. The present study aimed to evaluate the therapeutic effect of simultaneous administration of thyme essential oil (TEO) and endothelial progenitor stem cells (EPCs) on lipopolysaccharide (LPS)-induced sepsis in C57BL/6 mice. Sepsis was induced in C57Bl/6J mice by intraperitoneal injection of LPS, followed 2 h later by an intravenous injection of EPCs or oral administration of TEO or simultaneous administration of TEO and EPCs. After 10 days, the complete blood cell, renal and liver factors, serum levels of inflammatory cytokines, and angiogenic factors were measured. Simultaneous treatment with EPCs and TEO significantly increased the survival of mice with sepsis and modulated the inflammatory response by reducing the serum levels of pro-inflammatory cytokines. Moreover, this treatment significantly reduced the level of white blood cells and neutrophils and increased the number of red blood cells, the percentage of hematocrit, and hemoglobin. The combination of TEO with EPCs decreased organ injuries and was assessed by lower levels of the liver enzymes alanine aminotransferase and aspartate aminotransferase compared to the sepsis group. Administration of EPCs and TEO also significantly improved angiogenic factors, lung function, and toll-like receptor 4 expression. EPCs in combination with TEO increase survival in the LPS-induced sepsis mice model by acting on several targets. Thus, the combination of TEO with EPCs can be a feasible approach for the future clinical treatment and control of sepsis.

Cloperastine Reduces IL-6 Expression via Akt/GSK3/Nrf2 Signaling in Monocytes/Macrophages and Ameliorates Symptoms in a Mouse Sepsis Model Induced by Lipopolysaccharide.

Cloperastine (CLP) is a drug with a central antitussive effect that is used to treat bronchitis. Therefore, we have attempted to examine the anti-inflammatory effects of CLP. CLP reduced the secretion of interleukin (IL)-6, a pro-inflammatory cytokine, from RAW264.7 monocyte/macrophage-linage cells treated with lipopolysaccharide (LPS). IL-6 is a biomarker of sepsis and has been suggested to exacerbate its symptoms. We found that the intraperitoneal administration of CLP reduced IL-6 levels in the lungs and also improved hypothermia in mice with LPS-induced sepsis. CLP ameliorated kidney pathologies such as congestion and increased the survival rate of mice administered with a lethal dose of LPS. To reveal the mechanisms underlying the anti-inflammatory function of CLP, we analysed the intracellular signaling in LPS-treated RAW264.7 cells. CLP induced the phosphorylation of protein kinase B (Akt) and glycogen synthase kinase 3 (GSK3) and also increased the amount of nuclear factor erythroid-2-related factor 2 (Nrf2) in RAW264.7 cells with/without LPS. Wortmannin, an inhibitor of phosphoinositide 3-kinase (PI3K), reduced the upregulated phosphorylation levels of Akt and GSK3 and the increased amount of Nrf2. It also halted the reduction of IL-6 secretion caused by CLP. These results suggest that CLP has an anti-inflammatory function via Akt/GSK3/Nrf2 signaling and could be a candidate drug for the treatment of inflammatory diseases, including sepsis.

Antipsychotic medications and severe sepsis in schizophrenia: A nested case-control study.

BACKGROUND: Sepsis constitutes a condition that involves life-threatening organ dysfunction induced by severe infection. This nested case-control study investigated risk factors for severe sepsis and whether antipsychotic use is associated with severe sepsis risk in patients with schizophrenia, a topic that has not been comprehensively explored in previous studies. METHODS: We selected 39,432 patients with schizophrenia aged between 15 and 65 years from Taiwan's Psychiatric Inpatient Medical Claims database for the period 2000-2012. The case group comprised patients with severe sepsis after their first psychiatric admission (n = 1382). The case and control groups were randomly matched (1:4) by age, sex and first psychiatric admission (year) and finally comprised 1382 and 5528 individuals, respectively. We employed multivariable conditional logistic regression to identify (1) risk factors (physical illnesses and nonpsychiatric medications) and (2) antipsychotic-severe sepsis associations. RESULTS: Higher numbers of psychiatric admissions and physical illnesses such as delirium, cerebrovascular disease and cancer were significantly associated with a higher risk of severe sepsis. Furthermore, severe sepsis was associated with the use of antithrombotic agents, systemic corticosteroids and agents targeting the renin-angiotensin system. Clozapine (adjusted risk ratio = 1.65) and quetiapine (adjusted risk ratio = 1.59) use were associated with an increased risk of severe sepsis. The use of more than one antipsychotic drug could further increase this risk. CONCLUSION: Several physical illnesses and nonpsychiatric medications increase the risk of severe sepsis in patients with schizophrenia. Specifically, clozapine or quetiapine use significantly increased the risk of severe sepsis in these patients.

Complement C5 inhibition protects against hemolytic anemia and acute kidney injury in anthrax peptidoglycan-induced sepsis in baboons.

Late-stage anthrax infections are characterized by dysregulated immune responses and hematogenous spread of Bacillus anthracis, leading to extreme bacteremia, sepsis, multiple organ failure, and, ultimately, death. Despite the bacterium being nonhemolytic, some fulminant anthrax patients develop a secondary atypical hemolytic uremic syndrome (aHUS) through unknown mechanisms. We recapitulated the pathology in baboons challenged with cell wall peptidoglycan (PGN), a polymeric, pathogen-associated molecular pattern responsible for the hemostatic dysregulation in anthrax sepsis. Similar to aHUS anthrax patients, PGN induces an initial hematocrit elevation followed by progressive hemolytic anemia and associated renal failure. Etiologically, PGN induces erythrolysis through direct excessive activation of all three complement pathways. Blunting terminal complement activation with a C5 neutralizing peptide prevented the progressive deposition of membrane attack complexes on red blood cells (RBC) and subsequent intravascular hemolysis, heme cytotoxicity, and acute kidney injury. Importantly, C5 neutralization did not prevent immune recognition of PGN and shifted the systemic inflammatory responses, consistent with improved survival in sepsis. Whereas PGN-induced hemostatic dysregulation was unchanged, C5 inhibition augmented fibrinolysis and improved the thromboischemic resolution. Overall, our study identifies PGN-driven complement activation as the pathologic mechanism underlying hemolytic anemia in anthrax and likely other gram-positive infections in which PGN is abundantly represented. Neutralization of terminal complement reactions reduces the hemolytic uremic pathology induced by PGN and could alleviate heme cytotoxicity and its associated kidney failure in gram-positive infections.

Pimpinellin ameliorates macrophage inflammation by promoting RNF146-mediated PARP1 ubiquitination.

Macrophage inflammation plays a central role during the development and progression of sepsis, while the regulation of macrophages by parthanatos has been recently identified as a novel strategy for anti-inflammatory therapies. This study was designed to investigate the therapeutic potential and mechanism of pimpinellin against LPS-induced sepsis. PARP1 and PAR activation were detected by western blot or immunohistochemistry. Cell death was assessed by flow cytometry and western blot. Cell metabolism was measured with a Seahorse XFe24 extracellular flux analyzer. C57, PARP1 knockout, and PARP1 conditional knock-in mice were used in a model of sepsis caused by LPS to assess the effect of pimpinellin. Here, we found that pimpinellin can specifically inhibit LPS-induced macrophage PARP1 and PAR activation. In vitro studies showed that pimpinellin could inhibit the expression of inflammatory cytokines and signal pathway activation in macrophages by inhibiting overexpression of PARP1. In addition, pimpinellin increased the survival rate of LPS-treated mice, thereby preventing LPS-induced sepsis. Further research confirmed that LPS-induced sepsis in PARP1 overexpressing mice was attenuated by pimpinellin, and PARP1 knockdown abolished the protective effect of pimpinellin against LPS-induced sepsis. Further study found that pimpinellin can promote ubiquitin-mediated degradation of PARP1 through RNF146. This is the first study to demonstrate that pimpinellin inhibits excessive inflammatory responses by promoting the ubiquitin-mediated degradation of PARP1.

Hepatoprotective actions of melatonin by mainly modulating oxidative status and apoptosis rate in lipopolysaccharide-induced liver damage.

AIM: One of the serious complications of sepsis is liver damage and liver failure. This study aimed to evaluate the protective and therapeutic potential of melatonin in rats with lipopolysaccharide-induced sepsis. MAIN METHODS: Female Spraque-Dawley rats received single a dose of 7.5 mg/kg lipopolysaccharide in saline to create a 24-h sepsis model. One of the other groups received melatonin at a dose of 10 mg/kg/day beginning 1 week before sepsis induction to the end of the experiment. The melatonin group received the same doses of melatonin for the same duration but not lipopolysaccharide. The vehicle group received the same doses of saline, the vehicle of melatonin, for the same duration. Twenty-four hours after the last injection, the rats were decapitated. By appropriate histochemical, immunohistochemical, biochemical, and molecular techniques, anti-necrotic, anti-apoptotic, anti-necroptotic, anti-inflammatory, and antioxidant effects of melatonin were assessed. KEY FINDINGS: Lipopolysaccharide has disrupted liver functions by inducing oxidative stress, inflammation, necrotic, apoptotic, and necroptotic cell death, thus disrupting liver functions. Melatonin was found to be beneficial in terms of inhibiting the intrinsic pathway of apoptosis and tissue oxidant levels, stimulating tissue antioxidant enzyme levels, and restoring hepatocyte functions. SIGNIFICANCE: Melatonin, at those doses and duration, was found to be hepatoprotective by mainly modulating oxidative status and apoptosis rate, however, failed to significantly reduce histopathological damage. We suggest that longer-term melatonin administration may produce anti-inflammatory and anti-necrotic effects as well.

Inhibiting CD44-ICD Attenuates LPS-Induced Initiation of Hepatic Inflammation in Septic Mice.

Sepsis is a severe condition induced by microbial infection. It elicits a systemic inflammatory response, leading to multi-organ failure, and the liver, as a scavenger, plays a significant role in this process. Controlling hepatic inflammation and maintaining liver function is crucial in managing sepsis. CD44-ICD, as a CD44 signal transductor, is involved in multiple inflammatory responses. However, the role of CD44-ICD in lipopolysaccharide (LPS)-induced hepatic inflammation has not been investigated. Therefore, we aimed to examine whether CD44-ICD initiates hepatic inflammation in septic mice. We induced hepatic inflammation in mice by administering LPS. DAPT, a CD44-ICD inhibitor, was given to mice or Chang cells 30 min or 1 h before LPS administration (10 mg/kg, i.p., or 100 ng/mL, respectively). Inhibition of CD44-ICD decreased the level of aspartate aminotransferase (AST), alanine aminotransferase (ALT), hepatic necrosis, inflammatory cell infiltration, interleukin (IL)-1ß, inducible NO synthase (iNOS), nitric oxide (NO) production, nuclear factor (NF)κB signaling pathway proteins, and CD44 expression in mice. CD44-ICD inhibition also decreased IL-1ß and CD44 expression levels in Chang cells. CD44-ICD may be a primary regulatory function in CD44-associated LPS-induced initiation of hepatic inflammation in mice.

Melatonin Mediates Cardiac Tissue Damage under Septic Conditions Induced by Lipopolysaccharide.

Lipopolysaccharide (LPS) is known to induce oxidative stress and inflammation, leading to significant damage in cardiac tissues. This study investigates the protective effects of melatonin (MLT) against LPS-induced oxidative damage, inflammation, and apoptosis in rat heart tissue. Rats were divided into four groups (n = 6 per group): control, melatonin-treated, LPS-treated, and LPS + melatonin-treated. Oxidative stress markers, including thiobarbituric acid-reactive substances (TBARSs) and advanced oxidation protein products (AOPPs), were measured. Additionally, inflammatory markers, such as interleukin-6 (IL-6) levels, inducible nitric oxide synthase (iNOS) and nitric oxide (NO) content, and apoptotic markers, caspase-3, caspase-9, and acidic DNase activity, were evaluated. LPS treatment significantly increased TBARS, AOPP, and IL-6 levels, as well as the activity of caspase-3, acidic DNase and iNOS and NO content compared to the control group. Co-treatment with melatonin significantly reduced the levels of TBARS and AOPP levels, and caspase-3 and acidic DNase activities nearly matched those of the control group, while caspse-9 was still slightly increased. Interestingly, IL-6, iNOS and NO levels were significantly decreased but did not fully match the values in the control group. Melatonin mitigates LPS-induced oxidative stress, inflammation, and apoptosis in rat heart tissue by affecting all studied parameters, demonstrating its potential as a therapeutic agent for conditions characterized by oxidative stress and inflammation. Further research is warranted to explore the clinical applications of melatonin in cardiovascular diseases.

Nicotinamide mononucleotide alleviates endotoxin-induced acute lung injury by modulating macrophage polarization via the SIRT1/NF-κB pathway.

CONTEXT: Sepsis-induced acute lung injury (ALI) is a severe condition with limited effective therapeutics; nicotinamide mononucleotide (NMN) has been reported to exert anti-inflammatory activities. OBJECTIVE: This study explores the potential mechanisms by which NMN ameliorates sepsis-induced ALI in vivo and in vitro. MATERIALS AND METHODS: Cultured MH-S cells and a murine model were used to evaluate the effect of NMN on sepsis-induced ALI. MH-S cells were stimulated with LPS (1 µg/mL) and NMN (500 µM) for 12 h grouping as control, LPS, and LPS + NMN. Cell viability, apoptotic status, and M1/2 macrophage-related markers were detected. The mice were pretreated intraperitoneally with NMN (500 mg/kg) and/or EX-527 (5 mg/kg) 1 h before LPS injection and randomized into 7 groups (n = 8): control, LPS, LPS + NMN, NMN, LPS + NMN + EX-527 (a SIRT1 inhibitor), LPS + EX-527, and EX-527. After 12 h, lung histopathology, W/D ratio, MPO activity, NAD+ and ATP levels, M1/2 macrophage-related markers, and expression of the SIRT1/NF-κB pathway were detected. RESULTS: In MH-S cells, NMN significantly decreased the apoptotic rate from 12.25% to 5.74%. In septic mice, NMN improved the typical pathologic findings in lungs and reduced W/D ratio and MPO activity, but increased NAD+ and ATP levels. Additionally, NMN suppressed M1 but promoted M2 polarization, and upregulated the expression of SIRT1, with inhibition of NF-κB-p65 acetylation and phosphorylation. Furthermore, inhibition of SIRT1 reversed the effects of NMN-induced M2 macrophage polarization. CONCLUSIONS: NMN protects against sepsis-induced ALI by promoting M2 macrophage polarization via the SIRT1/NF-κB pathway, it might be an effective strategy for preventing or treating sepsis-induced ALI.

Drp1/p53 interaction mediates p53 mitochondrial localization and dysfunction in septic cardiomyopathy.

BACKGROUND: Previous studies have implicated p53-dependent mitochondrial dysfunction in sepsis induced end organ injury, including sepsis-induced myocardial dysfunction (SIMD). However, the mechanisms behind p53 localization to the mitochondria have not been well established. Dynamin-related protein 1 (Drp1), a mediator of mitochondrial fission, may play a role in p53 mitochondrial localization. Here we examined the role of Drp1/p53 interaction in SIMD using in vitro and murine models of sepsis. METHODS: H9c2 cardiomyoblasts and BALB/c mice were exposed to lipopolysaccharide (LPS) to model sepsis phenotype. Pharmacologic inhibitors of Drp1 activation (ψDrp1) and of p53 mitochondrial binding (pifithrin µ, PFTµ) were utilized to assess interaction between Drp1 and p53, and the subsequent downstream impact on mitochondrial morphology and function, cardiomyocyte function, and sepsis phenotype. RESULTS: Both in vitro and murine models demonstrated an increase in physical Drp1/p53 interaction following LPS treatment, which was associated with increased p53 mitochondrial localization, and mitochondrial dysfunction. This Drp1/p53 interaction was inhibited by ΨDrp1, suggesting that this interaction is dependent on Drp1 activation. Treatment of H9c2 cells with either ΨDrp1 or PFTµ inhibited the LPS mediated localization of Drp1/p53 to the mitochondria, decreased oxidative stress, improved cellular respiration and ATP production. Similarly, treatment of BALB/c mice with either ΨDrp1 or PFTµ decreased LPS-mediated mitochondrial localization of p53, mitochondrial ROS in cardiac tissue, and subsequently improved cardiomyocyte contractile function and survival. CONCLUSION: Drp1/p53 interaction and mitochondrial localization is a key prodrome to mitochondrial damage in SIMD and inhibiting this interaction may serve as a therapeutic target.

6-Formylindolo(3,2-b)carbazole Dampens Inflammation and Reduces Endotoxin-Induced Kidney Injury via Nrf2 Activation.

Patients with sepsis are at a high risk of morbidity and mortality due to multiple organ injuries caused by pathological inflammation. Although sepsis is accompanied by multiple organ injuries, acute renal injury is a significant contributor to sepsis morbidity and mortality. Thus, dampening inflammation-induced renal injury may limit severe consequences of sepsis. As several studies have suggested that 6-formylindolo(3,2-b)carbazole (FICZ) is beneficial for treating various inflammatory diseases, we aimed to examine the potential protective effect of FICZ on the acute endotoxin-induced sepsis model of kidney injury. To test this, male C57Bl/6N mice were injected with FICZ (0.2 mg/kg) or vehicle 1 h prior to an injection of either lipopolysaccharides (LPS) (10 mg/kg), to induce sepsis, or phosphate-buffered saline for 24 h. Thereafter, gene expression of kidney injury and pro-inflammatory markers, circulating cytokines and chemokines, and kidney morphology were assessed. Our results show that FICZ reduced LPS-induced acute injury in kidneys from LPS-injected mice. Furthermore, we found that FICZ dampens both renal and systemic inflammation in our sepsis model. Mechanistically, our data indicated that FICZ significantly upregulates NAD(P)H quinone oxidoreductase 1 and heme oxygenase 1 via aryl hydrocarbon receptor (AhR) and nuclear factor erythroid 2-related factor 2 (Nrf2) in the kidneys to lessen inflammation and improve septic acute kidney injury. Overall, the data of our study show that FICZ possesses a beneficial reno-protective effect against sepsis-induced renal injury via dual activation of AhR/Nrf2.

Maintenance of glutamine synthetase expression alleviates endotoxin-induced sepsis via alpha-ketoglutarate-mediated demethylation.

Glutamine synthetase (Glul) is the enzyme that synthesizes endogenous glutamine, which is responsible for critical metabolic pathways and the immune system. However, the role of Glul in regulating endotoxin (lipopolysaccharide, LPS)-induced sepsis remains unclear. Here, we found that Glul expression in macrophages was significantly inhibited in endotoxemia, and that Glul deletion induced macrophages to differentiate into the pro-inflammatory type and aggravated sepsis in mice. Mechanistically, TLR4/NF-κB-induced alpha-ketoglutarate (α-KG) depletion inhibits Glul expression through H3K27me3-mediated methylation in septic mice. Both Glul overexpression with adeno-associated virus (AAV) and restoration by replenishing α-KG can alleviate the severity of sepsis. In conclusion, the study demonstrated that Glul can regulate LPS-induced sepsis and provides a novel strategy for the treatment of this disease.

Dimethyl Fumarate Protects against Lipopolysaccharide- (LPS-) Induced Sepsis through Inhibition of NF-κB Pathway in Mice.

Sepsis is one of the most severe complications and causes of mortality in the clinic. It remains a great challenge with no effective treatment for clinicians worldwide. Inhibiting the release of proinflammatory cytokines during sepsis is considered as an important strategy for treating sepsis and improving survival. In the present study, we have observed the effect of dimethyl fumarate (DMF) on lipopolysaccharide- (LPS-) induced sepsis and investigated the possible mechanism. By screening a subset of the Johns Hopkins Drug Library, we identified DMF as a novel inhibitor of nitric oxide synthesis in LPS-stimulated RAW264.7 cells, suggesting that DMF could be a potential drug to treat sepsis. To further characterize the effect of DMF on LPS signaling, TNF-α, MCP-1, G-CMF, and IL-6 expression levels were determined by using cytokine array panels. In addition, an endotoxemia model with C57BL/6 mice was used to assess the in vivo efficacy of DMF on sepsis. The survival rate was assessed, and HE staining was performed to investigate histopathological damage to the organs. DMF was found to increase the survival of septic mice by 50% and attenuate organ damage, consistent with the reduction in IL-10, IL-6, and TNF-α (inflammatory cytokines) in serum. In vitro experiments revealed DMF's inhibitory effect on the phosphorylation of p65, IκB, and IKK, suggesting that the primary inhibitory effects of DMF can be attributed, at least in part, to the inhibition of phosphorylation of IκBα, IKK as well as nuclear factor-κB (NF-κB) upon LPS stimulation. The findings demonstrate that DMF dramatically inhibits NO and proinflammatory cytokine production in response to LPS and improves survival in septic mice, raising the possibility that DMF has the potential to be repurposed as a new treatment of sepsis.