CLP-induced Sepsis Research Articles

Extremely low frequency pulsed magnetic field inhibits myocardial damage and apoptosis in rats with CLP-induced sepsis: A histopathological and immunohistochemical evaluation.

We aimed to investigate whether pulsed magnetic fields (PMFs) (1 mT) may have preventive effects on myocardial damage and apoptosis in rats with sepsis. Twenty-eight adult Wistar albino rats were evenly distributed among four experimental groups, each consisting of seven rats: SH, LF-PMF, HF-PMF, and CLP. Sepsis induction was carried out via the cecal ligation and puncture (CLP) method, while rats in the LF-PMF and HF-PMF groups were exposed to 7.5 Hz and 15 Hz PMF, respectively, for duration of 24 hours. Following the removal of heart tissue, histological techniques were employed for the analysis. Histological scoring of apoptosis-related Bax, Bcl-2, and Acas-3 proteins as well as cTnI were performed in the heart tissue. The myocardial damage score significantly increased in the CLP group compared to the SH group (p < 0.05). Significant decreases were observed in Bcl-2 and cTnI protein levels in the CLP group, while significant increases were detected in the PMF groups (p < 0.05). An increase in Bax and Acas-3 protein levels, as well as the Bax/Bcl-2 ratio, was observed in the CLP group, with a decrease in the PMF groups (p < 0.05). The results demonstrate that PMF application has anti-apoptotic and therapeutic effects on septic heart tissue damage.

Skeletal myocyte-specific knockout of Ptpn1 and Ptpn2 enhances inflammatory response in muscle and increases mortality in polymicrobial sepsis

Abstract Background Critically ill patients often suffer from heart and skeletal muscle atrophy and failure (intensive care unit acquired weakness; ICUAW). Inflammation and sepsis are major risk factors for ICUAW. Critically ill patients with sepsis frequently develop insulin resistance that decreases protein synthesis and increases protein degradation in muscle eventually leading to ICUAW. The link between inflammation and insulin resistance is not well understood, but protein tyrosine phosphatases (PTP), that inhibit insulin signaling via insulin receptor (INSR) dephosphorylation as well as inflammation-associated pathways, are implicated. Hypothesis: We hypothesized that PTP1B and TC-PTP mediate inflammation-induced insulin resistance and muscle atrophy in heart and skeletal muscle. Methods and Results qRT-PCR analyses showed that the proinflammatory cytokines tumor necrosis factor (TNF), interleukin (IL)-1β, and IL-6 caused a ~2-fold increase in Ptpn1/PTP1B and Ptpn2/TC-PTP mRNA expression in C2C12 myocytes as well as in neonatal rat ventricular cardiomyocytes. Inhibition of the IL-6/GP130 pathway by siRNA and inhibitors in myocytes in vitro and skeletal muscle specific gp130 knockout mice in vivo attenuated IL-6-induced Ptpn1/PTP1B and Ptpn2/TC-PTP mRNA expression. CLP-induced polymicrobial sepsis was associated with a significant increase in gene expression and protein content of pro-inflammatory cytokines (Tnf, Il1b, Ifng) and leukocyte markers (CD68, CD11c, F4/80) in muscle of skeletal myocyte specific double knockout (Ptpn1+Ptpn2loxP/loxP, MCK cre, dKO) compared to wildtype (Ptpn1+Ptpn2loxP/loxP) mice in sepsis. This also resulted in a lower survival rate of dKO mice in sepsis (42% WT vs. 23% dKO). Immunohistological analyses revealed centralized nuclei, macrophage/monocyte infiltration and enhanced regeneration (Myh3, Pax7, Ki67) in tibialis anterior muscle of septic dKO mice. A strong activation of the NLRP3-inflammasome, as indicated by cleavage of caspase 1, GSDMD, GSDME and caspase 8, indicative for a pronounced inflammation and activated cell death pathways was observed in muscle of septic dKO mice. Conclusion The proinflammatory cytokine IL-6 increases the expression of Ptpn1 and Ptpn2 and enhances overall PTP activity. Selective inhibition of the IL-6R/GP130 signaling pathway by JAK2- and STAT3-inhibition as well as Gp130 deletion in myocytes in vivo attenuates those effects. Muscle-specific deletion of Ptpn1 and Ptpn2 in skeletal muscle leads to increased mortality, enhanced pro-inflammatory response and induced inflammatory, programmed cell death pathways in sepsis. Our data show that Ptpn1 and Ptpn2 play a key anti-inflammatory role in skeletal muscle.

Senescence landscape in the liver following sepsis and senolytics as potential therapeutics.

Senescence, caused by cell-cycle arrest, is a hallmark of aging. Senescence has also been described in embryogenesis, wound healing, and acute injuries. Sepsis is characterized by a dysregulated host response to infection, leading to organ dysfunction and mortality. Most of the pathophysiology of human sepsis is recapitulated in the mouse model of polymicrobial sepsis, developed by cecal ligation and puncture (CLP). In this report, we demonstrate a rapid onset of cellular senescence in the liver of mice subjected to CLP-induced sepsis, characterized by the upregulation of p21, p53, and other senescence markers, including SA-βgal. Using RNAscope, confocal microscopy, and flow cytometry, we further confirm the emergence of p21-expressing senescence phenotype in the liver 24 h after sepsis induction. Senescence was observed in several cell types in the liver, including hepatocytes, endothelial cells, and macrophages. We determined the landscape of senescence phenotype in murine sepsis by single-cell sequencing, which further ascertained that this cell fate is not confined to any particular cell type but displays a heterogeneous distribution. Furthermore, we observed a significant reduction in mortality following sepsis when mice were treated with senolytics, a combination of dasatinib and quercetin, before the CLP surgery. Our experiments unequivocally demonstrated a rapid development of cellular senescence with sepsis and, for the first time, described the senescence landscape in the sepsis liver and the possible role of senescent cells in the worsening outcome following sepsis.

Curcumin alleviates septic lung injury in mice by inhibiting TXNIP/TRX-1/GPX4-mediated ferroptosis

To investigate whether curcumin alleviates septic lung injury by inhibiting ferroptosis through modulating the TXNIP/TRX-1/GPX4 pathway. Male C57BL/6 mice were randomly divided into Sham group, cecal ligation puncture (CLP)-induced sepsis group, CLP with curcumin treatment (50, 100, and 200 mg/kg) groups, and CLP with both curcumin (200 mg/kg) and TRX-1 inhibitor PX-12 (25 mg/kg) treatment group. Inflammatory factors, MDA, MPO, and GSH levels in the lung tissue of the mice were detected. Beas-2B cells stimulated with lipopolysaccharide (LPS; 1 μg/mL) were treated with 2.5, 5, or 10 μmol/L curcumin or with 10 μmol/L curcumin combined with 5 μmol/L PX-12, and the changes in MDA, Fe2+ and ROS levels were assessed. Western blotting was performed to detect the protein expressions of TXNIP, TRX-1, GPX4 and X-CT in both the mouse lung tissues and Beas-2B cells. The mice with CLP-induced sepsis showed severe lung injury with elevated expressions of IL-6, IL-1β, TNF-α, MDA and MPO and decreased GSH expression. In Beas-2B cells, LPS stimulation significantly increased MDA and Fe2+ levels and ROS release, increased TXNIP protein expression, and lowered the protein expression levels of TRX-1, GPX4 and X-CT, and these changes were also observed in the septic mice. Curcumin treatments at different concentrations obviously alleviated lung injury in the septic mice and reduced LPS-induced injury in Beas-2B cells. Curcumin significantly decreased the release of inflammatory factors, MDA and MPO, increased GSH level, lowered Fe2+, MDA and ROS levels, increased TXNIP protein expression, and lowered the protein expressions of TRX-1, GPX4 and X-CT in both septic mouse lung tissues and LPS-stimulated Beas-2B cells. The protective effect of curcumin was effectively blocked by PX-12 treatment. Curcumin inhibits ferroptosis and alleviates septic lung injury in mice by elevating TRX-1 and GPX4 and decreasing TXNIP in the lung tissue.

Evaluation of antioxidant prophylactic effects of parsley (Petroselinum crispum) on sepsis following cecal ligation and puncture

Objective: Sepsis causes the release of free oxygen radicals that disrupt membrane integrity, and damage to Mitochondria due to the production of free oxygen radicals and oxidation leads to exacerbation of sepsis, Cecal ligation and puncture (CLP) in rats mimics the characteristics and course of clinical sepsis (Hubbard et al., 2005). Methods: We evaluated the antioxidant effects of Petroselinum crispum (Pc) in a cecal ligation and puncture (CLP)-induced rat sepsis model, in a rat model of sepsis caused by cecal ligation and puncture (CLP). Wistar albino rats were separated into four groups of eight groups: a sham group with incised and sutured abdomens; a Pc extract (PcE) group, which was given 2 g/kg parsley extract for 14 days by gastric gavage; a CLP group, which was subjected to sepsis caused by CLP; and a PcE + CLP group, which was given parsley extract for 14 days. PcE was given for 14 days, after which sepsis was induced via the CLP procedure. The groups were compared in terms of hemogram, biochemical and histological characteristics. Results: The administration of PcE before CLP-induced sepsis increases neutrophil counts, PLTs and TASs, which decrease with sepsis, and decreases biochemical changes (BUN, AST, ALT, LDH, TOS, and OSI), which increase with sepsis, to protect against sepsis. Compared with that in the CLP group, the severity of intestinal infiltration was significantly lower in the PcE + CLP group; however, the degree of epithelial damage in the PcE + CLP group was similar to that in the CLP group. In the PcE + CLP group, the crypt and villus lengths were greater, and the decrease in Paneth cell degranulation intensity was greater than that in the CLP group. Conclusion: Additionally, the morphology of the cells in the PcE + CLP group was similar to that in the sham group. PcE has potential as a prophylactic agent for sepsis.

Vincamine exerts hepato-protective activity during colon ligation puncture-induced sepsis by modulating oxidative stress, apoptosis, and TNFα/Nrf-2/Keap-1 signaling pathways

Sepsis is a pathological and biochemical disorder induced by numerous infections, leading to critical illness and a high mortality rate worldwide. Vincamine is an indole alkaloid compound obtained from the leaves of Vinca minor. The present study aims to investigate the hepato-protective activity of vincamine during colon ligation puncture (CLP)-induced sepsis at the molecular level. Sepsis was induced using the CLP model. Liver function enzymes such as ALT and AST were analyzed. The hepatic antioxidant status (SOD and GSH), lipid peroxidation (MDA), the pro-inflammatory cytokines (TNFα, IL-6, and IL-1β), bax, bcl2, and cleaved caspase 3 proteins were estimated. Nrf-2 and Keap-1 protein expression was evaluated using western blotting. Histopathological investigation of liver tissues was also performed. CLP-induced sepsis led to liver injury through the elevation of ALT and AST liver enzymes. Oxidative stress was initiated during CLP via the suppression of hepatic GSH content and SOD activity and the elevation of MDA. The inflammatory condition was activated by the upregulation of TNFα, IL-6, IL-1β, and Keap-1 and the downregulation of Nrf-2 proteins. The apoptosis was initiated through the activation of bax and cleaved caspase 3 protein expression and inhibition of bcl2 protein expression. However, vincamine significantly improved the hepatic histological abnormalities and decreased liver enzymes (ALT and AST). It ameliorated oxidative stress, as evidenced by reducing the hepatic MDA content and increasing the SOD activity and GSH content. Moreover, vincamine reduced the hepatic content of TNFα, IL-6, IL-1β, and Keap-1 and increased Nrf-2 protein expression. Additionally, it upregulated bcl2 protein expression and downregulated bax and cleaved caspase 3 protein expression. Vincamine exhibited hepato-protective potential during CLP-induced sepsis via the cross-connection of antioxidant, anti-inflammatory, and anti-apoptotic activities by modulating TNFα/IL-6/IL-1β/Nrf-2/Keap-1 and regulating bax/bcl2/cleaved caspase 3 signaling pathways.

Plexin C1 influences immune response to intracellular LPS and survival in murine sepsis

BackgroundIntracellular sensing of lipopolysaccharide (LPS) is essential for the immune response against gram-negative bacteria and results in activation of caspase-11 and pyroptotic cell death with fatal consequences in sepsis. We found the neuronal guidance receptor plexin C1 (PLXNC1) influences the intracellular response to LPS.MethodsWe employed a murine model of sepsis via cecal ligation and binding (CLP), using PLXNC1-/- mice and littermate controls, and additionally transfected murine bone-marrow-derived macrophages (BMDMs) from both genotypes with LPS to achieve activation of the noncanonical inflammasome ex vivo. Additionally, we transfected the PLXNC1 ligand SL4c-d in vivo and ex vivo to examine its effect on intracellular LPS response.ResultsWe found the neuronal guidance receptor PLXNC1 dampens the intracellular response to LPS by interacting with adenylate cyclase 4 (ADCY4) and protein kinase A activity, which in turn diminishes caspase-11 expression. The absence of PLXNC1 results in excessive inflammation marked by increased cytokine release, increased secondary organ injury and reduced sepsis survival in a murine sepsis model induced by CLP. Notably, administration of SL4c-d—peptide ligand of PLXNC1—reduces the inflammatory response during CLP-induced sepsis and improves survival.ConclusionsThese results elucidate a previously unknown mechanism for PLXNC1 suppressing excessive noncanonical inflammasome activity and offer a new potential target for treatment of sepsis with its detrimental effects.

Evaluation of the Efficacy of Tofacitinib, a JAK Inhibitor, in Alleviating Sepsis-Induced Multiple Organ Dysfunction Syndrome.

Sepsis, a life-threatening condition triggered by an uncontrolled response to infection, results in a systemic inflammatory response syndrome (SIRS) and the failure of multiple organs leading to multiple organ dysfunction (MODS). In the present study, we investigated the therapeutic potential of tofacitinib (TOFA), an FDA-approved inhibitor of JAK1 and JAK3 against sepsis, using a mouse model induced by cecal ligation puncture (CLP). Swiss albino mice were employed to replicate the CLP-induced sepsis model and were randomly divided into four groups: control, CLP, 150 mg/kg TOFA, and 300 mg/kg TOFA. Six hours after the last TOFA dose, we collected blood and tissue samples from the liver, lungs, kidneys, and spleen for histological analysis. Blood samples were used to assess granulocyte and lymphocyte percentages. Throughout the experiment, we monitored body weight and short-term survival. Our comparative histological analysis revealed that 150 mg/kg TOFA had a protective effect against multiple organ damage. Conversely, the study highlighted the harmful effects of 300 mg/kg TOFA, primarily due to liver and renal toxicity within this group. In summary, our findings demonstrate that tofacitinib at an optimal dose of 150 mg/kg showed promise as a potential therapeutic intervention for sepsis-induced multiple organ failure. However, caution is warranted when considering higher dosages.

Heterogeneous Patterns of Endothelial NF-κB p65 and MAPK c-Jun Activation, Adhesion Molecule Expression, and Leukocyte Recruitment in Lung Microvasculature of Mice with Sepsis.

Sepsis is an uncontrolled systemic inflammatory response to an infection that can result in acute failure of the function of the lung called acute respiratory distress syndrome. Leukocyte recruitment is an important hallmark of acute lung failure in patients with sepsis. Endothelial cells (EC) participate in this process by facilitating tethering, rolling, adhesion, and transmigration of leukocytes via adhesion molecules on their cell surface. In in vivo studies, endothelial nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) p65 and mitogen-activated protein kinase (MAPK) c-Jun intracellular signal transduction pathways were reported to regulate the expression of adhesion molecules. Mice underwent cecal ligation and puncture (CLP) to induce polymicrobial sepsis and were sacrificed at different time points up to 72 h after sepsis onset. Immunohistochemistry and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) analyses were used to determine the kinetics of nuclear localization of p65 and c-Jun in EC, expression and location of adhesion molecules E-selectin and vascular cell adhesion molecule 1 (VCAM-1). Furthermore, the extent and location of leukocyte recruitment were assessed based on Ly6G staining of neutrophils, cluster determinant (CD) 3 staining of T lymphocytes, and CD68 staining of macrophages. In all pulmonary microvascular beds, we identified p65 and c-Jun nuclear accumulation in a subset of endothelial cells within the first 24 h after CLP-sepsis initiation. E-selectin protein was expressed in a subset of microvessels at 4 and 7 h after sepsis initiation, while VCAM-1 was expressed in a scattered pattern in alveolar tissue and microvessels, without discernible changes during sepsis development. CLP-induced sepsis predominantly promoted the accumulation of neutrophils and T lymphocytes 4 and 7 h after disease onset. Neutrophil accumulation occurred in all pulmonary microvascular beds, while T lymphocytes were present in alveolar tissue and postcapillary venules. Taken together, nuclear localization of p65 and c-Jun in EC and neutrophil recruitment could be associated with induced E-selectin expression in the pulmonary microvessels in CLP-septic mice at the early stage of the disease. In alveolar capillaries, on the other hand, activation of these molecular pathways and leukocyte accumulation occurred in the absence of E-selectin or VCAM-1. Endothelial activation and leukocyte recruitment in sepsis-induced lung injury are regulated by multiple, heterogeneously controlled mechanisms, which vary depending on the type of microvascular bed involved.

Mechanism of Extracellular Histone-Induced Endothelial Dysfunction Leading to Sepsis-Induced Acute Respiratory Distress Syndrome

Sepsis-induced acute respiratory distress syndrome (ARDS) is an independent risk factor for mortality in critically ill septic patients. However, effective therapeutic targets are still unavailable due to the lack of understanding of its unclear pathogenesis. With increasing understanding in the roles of circulating histones and endothelial dysfunction in sepsis, we aimed to investigate the mechanism of histone-induced endothelial dysfunction leading to sepsis-induced ARDS and to provide experimental support for histone-targeted treatment of sepsis-induced ARDS. First of all, in vitro experiments were conducted. Human umbilical vein endothelial cells (HUVEC) were stimulated with gradient concentrations of histones to explore for the optimal stimulation concentration in vitro. Then, HUVEC were exposed to histones at an optimal concentration with or without resatorvid (TAK-242), a selective inhibitor of Toll-like receptor 4 (TLR4), for 24 hours for modeling. The cells were divided into 4 groups: 1) the blank control group, 2) the blank control+TAK-242 intervention group, 3) the histone stimulation group, and 4) the histone+TAK-242 intervention group. HUVEC apoptosis was determined by flow cytometry, VE-Cadherin expression in endothelial cells was determined by Western blot, and the integrity of adhesion connections between endothelial cells was evaluated with confocal fluorescence microscopic images. Male C57BL/6 mice aged 6-8 weeks and weighing 22-25 g were used for the in vivo experiment. Then, the mice were given cecal ligation and puncture (CLP) as well as histone injection at 50 mg/kg via the tail vein for sepsis modeling. The experimental animals were divided into 6 groups: 1) the blank control group, 2) the blank control+TAK-242 intervention group, 3) the CLP model group, 4) the CLP+TAK-242 intervention group, 5) the histone model group, and 6) the histone+TAK-242 intervention group. After 24 h, the concentrations of serum interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) were determined using ELISA kits. Western blot was performed to determine the expression of vascular endothelial (VE)-cadherin in the lung tissue. Hematoxylin and eosin (HE) staining was performed to observe the pathological changes in the lung tissue of the mice. Evans Blue was injected via the tail vein 30 min before the mice were sacrificed. Lung tissue was collected after the mice were sacrificed. Then, the concentrations of Evans blue dye per unit mass in the lung tissue from mice of different groups were evaluated, the rates of pulmonary endothelial leakage were calculated, and the integrity of the pulmonary endothelial barrier was evaluated. The results of the in vitro experiment showed that, compared with those of the control group, HUVEC apoptosis was significantly increased under histone stimulation (P<0.05), the expression of VE-cadherin was decreased (P<0.05), and the integrity of adherens junctions between endothelial cells was damaged. TAK-242 can significantly inhibit histone-induced HUVEC apoptosis and VE-cadherin expression reduction and maintain the integrity of adherens junctions between endothelial cells. According to the findings from the in vivo experiments, in mice with CLP-induced and histone-induced sepsis, TAK-242 effectively alleviated the increase in serum concentrations of IL-6 and TNF-α, reduced the downregulation of VE-cadherin expression in the lung tissue (P<0.05), decreased endothelial permeability of the lung vessels, and improved pathological injury in the lung tissue. By binding to TLR-4, histone decreases VE-cadherin expression on the surface of vascular endothelial cells, disrupts the integrity of intercellular adherens junctions, and triggers pathological damage to lung tissue. Using TLR-4 inhibitors can prevent sepsis-induced ARDS in histone-induced sepsis.

Metformin Mitigates Sepsis-Induced Acute Lung Injury and Inflammation in Young Mice by Suppressing the S100A8/A9-NLRP3-IL-1β Signaling Pathway.

Globally, the subsequent complications that accompany sepsis result in remarkable morbidity and mortality rates. The lung is among the vulnerable organs that incur the sepsis-linked inflammatory storm and frequently culminates into ARDS/ALI. The metformin-prescribed anti-diabetic drug has been revealed with anti-inflammatory effects in sepsis, but the underlying mechanisms remain unclear. This study aimed to ascertain metformin's effects and functions in a young mouse model of sepsis-induced ALI. Mice were randomly divided into 4 groups: sham, sham+ Met, CLP, and CLP+ Met. CLP was established as the sepsis-induced ALI model accompanied by intraperitoneal metformin treatment. At day 7, the survival state of mice was noted, including survival rate, weight, and M-CASS. Lung histological pathology and injury scores were determined by hematoxylin-eosin staining. The pulmonary coefficient was used to evaluate pulmonary edema. Furthermore, IL-1β, CCL3, CXCL11, S100A8, S100A9 and NLRP3 expression in tissues collected from lungs were determined by qPCR, IL-1β, IL-18, TNF-α by ELISA, caspase-1, ASC, NLRP3, P65, p-P65, GSDMD-F, GSDMD-N, IL-1β and S100A8/A9 by Western blot. The data affirmed that metformin enhanced the survival rate, lessened lung tissue injury, and diminished the expression of inflammatory factors in young mice with sepsis induced by CLP. In contrast to sham mice, the CLP mice were affirmed to manifest ALI-linked pathologies following CLP-induced sepsis. The expressions of pro-inflammatory factors, for instance, IL-1β, IL-18, TNF-α, CXCL11, S100A8, and S100A9 are markedly enhanced by CLP, while metformin abolished this adverse effect. Western blot analyses indicated that metformin inhibited the sepsis-induced activation of GSDMD and the upregulation of S100A8/A9, NLRP3, and ASC. Metformin could improve the survival rate, lessen lung tissue injury, and minimize the expression of inflammatory factors in young mice with sepsis induced by CLP. Metformin reduced sepsis-induced ALI via inhibiting the NF-κB signaling pathway and inhibiting pyroptosis by the S100A8/A9-NLRP3-IL-1β pathway.

CD5L as a promising biological therapeutic for treating sepsis

Sepsis results from systemic, dysregulated inflammatory responses to infection, culminating in multiple organ failure. Here, we demonstrate the utility of CD5L for treating experimental sepsis caused by cecal ligation and puncture (CLP). We show that CD5L’s important features include its ability to enhance neutrophil recruitment and activation by increasing circulating levels of CXCL1, and to promote neutrophil phagocytosis. CD5L-deficient mice exhibit impaired neutrophil recruitment and compromised bacterial control, rendering them susceptible to attenuated CLP. CD5L-/- peritoneal cells from mice subjected to medium-grade CLP exhibit a heightened pro-inflammatory transcriptional profile, reflecting a loss of control of the immune response to the infection. Intravenous administration of recombinant CD5L (rCD5L) in immunocompetent C57BL/6 wild-type (WT) mice significantly ameliorates measures of disease in the setting of high-grade CLP-induced sepsis. Furthermore, rCD5L lowers endotoxin and damage-associated molecular pattern (DAMP) levels, and protects WT mice from LPS-induced endotoxic shock. These findings warrant the investigation of rCD5L as a possible treatment for sepsis in humans.

IM156, a new AMPK activator, ameliorates polymicrobial sepsis by regulating inflammatory responses

Abstract IM156, a biguanide with a higher potency of AMP-activated protein kinase (AMPK) activation than metformin, exhibits inhibitory activity against angiogenesis and cancer. In this study, we explored the anti-inflammatory effects of IM156 against polymicrobial sepsis. Administration of IM156 significantly improved the survival rate and tissue damage in cecal ligation and puncture (CLP)-induced sepsis. Mechanistically, IM156 markedly reduced the number of bacterial cells in the peritoneal fluid and peripheral blood in a CLP-induced sepsis model. IM156 also inhibited splenocyte apoptosis and the production of inflammatory cytokines, including IL-1β, IL-6, and IL-10, in CLP mice. Furthermore, IM156 strongly inhibited the reactive oxygen species (ROS) generation by enhancing antioxidative effects, which can lead to reduced neutrophil extracellular trap (NET) formation in response to lipopolysaccharide. In conclusion, these findings collectively indicate that IM156 can suppress the inflammatory response and provide protection against polymicrobial sepsis. These results suggest the potential of IM156 as a novel therapeutic agent for sepsis control.

Mechanism of electro-acupuncture in alleviating intestinal injury in septic mice via polyamine-related M2-macrophage polarization.

The objective of this study was to investigate the impact of electro-acupuncture (EA) on sepsis-related intestinal injury and its relationship with macrophage polarization. A sepsis model was established using cecal ligation and puncture (CLP) to assess the effectiveness of EA. The extent of pathological injury was evaluated using Chiu's score, the expression of ZO-1 and Ocludin, and the impact on macrophage polarization was examined through flow cytometry and immunofluorescence staining. The expression of spermidine, one type of polyamine, and ornithine decarboxylase (ODC) was measured using ELISA and PCR. Once the efficacy was determined, a polyamine depletion model was created, and the role of polyamines was reassessed by evaluating efficacy and observing macrophage polarization. EA treatment reduced the Chiu's score and increased the expression of ZO-1 and Ocludin in the intestinal tissue of septic mice. It inhibited the secretion of IL-1β and TNF-α, promoted the polarization of M2-type macrophages, increased the secretion of IL-10, and upregulated the expression of Arg-1, spermidine, and ODC. However, after depleting polyamines, the beneficial effects of EA on alleviating intestinal tissue damage and modulating macrophage polarization disappeared. The mechanism underlying the alleviation of intestinal injury associated with CLP-induced sepsis by EA involves with the promotion of M2-type macrophage polarization mediated by spermidine expression.

OTUD5 promotes the inflammatory immune response by enhancing MyD88 oligomerization and Myddosome formation

Myddosome is an oligomeric complex required for the transmission of inflammatory signals from TLR/IL1Rs and consists of MyD88 and IRAK family kinases. However, the molecular basis for the self-assemble of Myddosome proteins and regulation of intracellular signaling remains poorly understood. Here, we identify OTUD5 acts as an essential regulator for MyD88 oligomerization and Myddosome formation. OTUD5 directly interacts with MyD88 and cleaves its K11-linked polyubiquitin chains at Lys95, Lys231 and Lys250. This polyubiquitin cleavage enhances MyD88 oligomerization after LPS stimulation, which subsequently promotes the recruitment of downstream IRAK4 and IRAK2 to form Myddosome and the activation of NF-κB and MAPK signaling and production of inflammatory cytokines. Consistently, Otud5-deficient mice are less susceptible to LPS- and CLP-induced sepsis. Taken together, our findings reveal a positive regulatory role of OTUD5 in MyD88 oligomerization and Myddosome formation, which provides new sights into the treatment of inflammatory diseases.

Impact of Exercise Training on Survival Rate and Neural Cell Death in Sepsis Through the Maintenance of Redox Equilibrium.

Sepsis-related deaths occur during both the early proinflammatory and the late immunosuppressive phases of the condition. The balance of pro- and anti-inflammatory responses is influenced by damaged cells that die via either proinflammatory necroptosis or anti-inflammatory apoptosis. Both forms of cell death may be mediated by reactive oxygen species (ROS) generated during the proinflammatory response. Recent evidence suggests that exercise training boosts antioxidative capacity and could offer protection against sepsis. Given these findings, we aimed to examine the impact of exercise training on neural cell death in the context of sepsis. We assessed the effectiveness of exercise in reducing ROS production and the inflammatory response using a cecal ligation and puncture (CLP)-induced sepsis model. Forty C57BL/6N male mice were randomly divided into 2 groups: control (CLP-Con; n=20) and experimental (CLP-Ex; n=20). Before the induction of sepsis by CLP, the CLP-Ex mice underwent interval training on a treadmill 3 days per week for 8 weeks. Each day involved 10 cycles of 2 minutes at 8 m/min and 2 minutes at 15 m/min. After the CLP procedure, we monitored the survival of 10 mice from each group over a 30-hour period. The findings indicated that exercise training increased the survival rate among mice with CLP-induced sepsis by enhancing antioxidative capacity and delaying the transition from a hyperdynamic to an immunosuppressive state. Exercise training may delay the progression from the hyperdynamic state to the hypodynamic phase of sepsis by increasing antioxidant capacity and reducing apoptotic cell death.

The Dual Role of Neutrophil Extracellular Traps (NETs) in Sepsis and Ischemia-Reperfusion Injury: Comparative Analysis across Murine Models.

A better understanding of the function of neutrophil extracellular traps (NETs) may facilitate the development of interventions for sepsis. The study aims to investigate the formation and degradation of NETs in three murine sepsis models and to analyze the production of reactive oxygen species (ROS) during NET formation. Murine sepsis was induced by midgut volvulus (720° for 15 min), cecal ligation and puncture (CLP), or the application of lipopolysaccharide (LPS) (10 mg/kg body weight i.p.). NET formation and degradation was modulated using mice that were genetically deficient for peptidyl arginine deiminase-4 (PAD4-KO) or DNase1 and 1L3 (DNase1/1L3-DKO). After 48 h, mice were killed. Plasma levels of circulating free DNA (cfDNA) and neutrophil elastase (NE) were quantified to assess NET formation and degradation. Plasma deoxyribonuclease1 (DNase1) protein levels, as well as tissue malondialdehyde (MDA) activity and glutathione peroxidase (GPx) activity, were quantified. DNase1 and DNase1L3 in liver, intestine, spleen, and lung tissues were assessed. The applied sepsis models resulted in a simultaneous increase in NET formation and oxidative stress. NET formation and survival differed in the three models. In contrast to LPS and Volvulus, CLP-induced sepsis showed a decreased and increased 48 h survival in PAD4-KO and DNase1/1L3-DKO mice, when compared to WT mice, respectively. PAD4-KO mice showed decreased formation of NETs and ROS, while DNase1/1L3-DKO mice with impaired NET degradation accumulated ROS and chronicled the septic state. The findings indicate a dual role for NET formation and degradation in sepsis and ischemia-reperfusion (I/R) injury: NETs seem to exhibit a protective capacity in certain sepsis paradigms (CLP model), whereas, collectively, they seem to contribute adversely to scenarios where sepsis is combined with ischemia-reperfusion (volvulus).

ACE2 Rescues Sepsis-Associated Encephalopathy by Reducing Inflammation, Oxidative Stress, and Neuronal Apoptosis via the Nrf2/Sestrin2 Signaling Pathway.

Neuroinflammation and oxidative stress contribute to the progression of sepsis-associated encephalopathy (SAE). Angiotensin-converting enzyme 2 (ACE2) is considered to be a neuroprotective factor due to its anti-inflammatory and antioxidant properties. However, the role of ACE2 on myeloid cells in regulating SAE and the underlying mechanism warrants further exploration. SAE was induced in ACE2 transgenic (TG), knockout (KO), and bone marrow (BM) chimeric mice by cecal ligation and puncture (CLP). The expression levels of apoptosis-, oxidation- and neuroinflammation-associated mediators and morphological changes were monitored by quantitative real-time PCR analyses and histological examinations in the cortex of septic mice. The contents of angiotensin (Ang) II and Ang-(1-7) along with the activity of ACE2 were examined with commercial kits. The expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and Sestrin2 was detected by immunoblotting analysis. Our results indicated that the expression of cortical ACE2 was significantly reduced in the early phase of CLP-induced sepsis. Moreover, ACE2 overexpression in TG mice conferred neuroprotection against sepsis, as evidenced by alleviated neuronal apoptosis, oxidative stress, and proinflammatory M1-like microglial polarization, accompanied by upregulation of the Ang-(1-7), Nrf2, and Sestrin2 protein levels. Conversely, ACE2 deficiency in KO mice exacerbated SAE. The neuroprotective effects of ACE2 were further confirmed in wild-type mice transplanted with ACE2-TG and KO BM cells. Therefore, our data suggest that myeloid ACE2 exerts a protective role in the pathogenesis of SAE, potentially by activating Ang-(1-7)-Nrf2/sestrin2 signaling pathway, and highlight that upregulating ACE2 expression and activity may represent a promising approach for the treatment of SAE in patients with sepsis.

TIGIT regulates CD4+ T cell immunity against polymicrobial sepsis.

Sepsis is one of the major causes of death and increased health care burden in modern intensive care units. Immune checkpoints have been prompted to be key modulators of T cell activation, T cell tolerance and T cell exhaustion. This study was designed to investigate the role of the negative immune checkpoint, T cell immunoglobulin and ITIM domain (TIGIT), in the early stage of sepsis. An experimental murine model of sepsis was developed by cecal ligation and puncture (CLP). TIGIT and CD155 expression in splenocytes at different time points were assessed using flow cytometry. And the phenotypes of TIGIT-deficient (TIGIT-/-) and wild-type (WT) mice were evaluated to explore the engagement of TIGIT in the acute phase of sepsis. In addition, the characteristics were also evaluated in the WT septic mice pretreated with anti-TIGIT antibody. TIGIT and CD155 expression in tissues was measured using real-time quantitative PCR and immunofluorescence staining. Proliferation and effector function of splenic immune cells were evaluated by flow cytometry. Clinical severity and tissue injury were scored to evaluate the function of TIGIT on sepsis. Additionally, tissue injury biomarkers in peripheral blood, as well as bacterial load in peritoneal lavage fluid and liver were also measured. The expression of TIGIT in splenic T cells and NK cells was significantly elevated at 24 hours post CLP.TIGIT and CD155 mRNA levels were upregulated in sepsis-involved organs when mice were challenged with CLP. In CLP-induced sepsis, CD4+ T cells from TIGIT-/- mice shown increased proliferation potency and cytokine production when compared with that from WT mice. Meanwhile, innate immune system was mobilized in TIGIT-/- mice as indicated by increased proportion of neutrophils and macrophages with potent effector function. In addition, tissue injury and bacteria burden in the peritoneal cavity and liver was reduced in TIGIT-/- mice with CLP induced sepsis. Similar results were observed in mice treated with anti-TIGIT antibody. TIGIT modulates CD4+ T cell response against polymicrobial sepsis, suggesting that TIGIT could serve as a potential therapeutic target for sepsis.

Antiseptic Functions of CGK012 against HMGB1-Mediated Septic Responses.

High mobility group box 1 (HMGB1), a protein with important functions, has been recognized as a potential therapeutic target for the treatment of sepsis. One possible mechanism for this is that inhibiting HMGB1 secretion can exert antiseptic effects, which can restore the integrity of the vascular barrier. (7S)-(+)-cyclopentyl carbamic acid 8,8-dimethyl-2-oxo-6,7-dihydro-2H,8H-pyrano[3,2-g]chromen-7-yl-ester (CGK012) is a newly synthesized pyranocoumarin compound that could function as a novel small-molecule inhibitor of the Wnt/β-catenin signaling pathway. However, no studies have yet determined the effects of CGK012 on sepsis. We investigated the potential of CGK012 to attenuate the excessive permeability induced by HMGB1 and enhance survival rates in a mouse model of sepsis with reduced HMGB1 levels following lipopolysaccharide (LPS) treatment. In both LPS-stimulated human endothelial cells and a mouse model exhibiting septic symptoms due to cecal ligation and puncture (CLP), we assessed proinflammatory protein levels and tissue damage biomarkers as indicators of reduced vascular permeability. CGK012 was applied after induction in human endothelial cells exposed to LPS and the CLP-induced mouse model of sepsis. CGK012 effectively mitigated excessive permeability and suppressed HMGB1 release, resulting in improved vascular stability, decreased mortality, and enhanced histological conditions in the mouse model of CLP-induced sepsis. In conclusion, our findings indicate that CGK012 treatment in mice with CLP-induced sepsis diminished HMGB1 release and increased the survival rate, suggesting its potential as a pharmaceutical intervention for sepsis.