Sepsis-induced Organ Dysfunction Research Articles

From Molecular Mechanisms to Clinical Therapy: Understanding Sepsis-Induced Multiple Organ Dysfunction.

Sepsis-induced multiple organ dysfunction arises from the highly complex pathophysiology encompassing the interplay of inflammation, oxidative stress, endothelial dysfunction, mitochondrial damage, cellular energy failure, and dysbiosis. Over the past decades, numerous studies have been dedicated to elucidating the underlying molecular mechanisms of sepsis in order to develop effective treatments. Current research underscores liver and cardiac dysfunction, along with acute lung and kidney injuries, as predominant causes of mortality in sepsis patients. This understanding of sepsis-induced organ failure unveils potential therapeutic targets for sepsis treatment. Various novel therapeutics, including melatonin, metformin, palmitoylethanolamide (PEA), certain herbal extracts, and gut microbiota modulators, have demonstrated efficacy in different sepsis models. In recent years, the research focus has shifted from anti-inflammatory and antioxidative agents to exploring the modulation of energy metabolism and gut microbiota in sepsis. These approaches have shown a significant impact in preventing multiple organ damage and mortality in various animal sepsis models but require further clinical investigation. The accumulation of this knowledge enriches our understanding of sepsis and is anticipated to facilitate the development of effective therapeutic strategies in the future.

Multienzyme Active Nanozyme for Efficient Sepsis Therapy through Modulating Immune and Inflammation Inhibition.

Sepsis, a life-threatening condition caused by a dysregulated immune response to infection, leads to systemic inflammation, immune dysfunction, and multiorgan damage. Various oxidoreductases play a very important role in balancing oxidative stress and modulating the immune response, but they are stored inconveniently, environmentally unstable, and expensive. Herein, we develop multifunctional artificial enzymes, CeO2 and Au/CeO2 nanozymes, exhibiting five distinct enzyme-like activities, namely, superoxide dismutase, catalase, glutathione peroxidase, peroxidase, and oxidase. These artificial enzymes have been used for the biocatalytic treatment of sepsis via inhibiting inflammation and modulating immune responses. These nanozymes significantly reduce reactive oxygen species and proinflammatory cytokines, achieving multiorgan protection. Notably, CeO2 and Au/CeO2 nanozymes with enzyme-mimicking activities can be particularly effective in restoring immunosuppression and maintaining homeostasis. The redox nanozyme offers a promising dual-protective strategy against sepsis-induced inflammation and organ dysfunction, paving the way for biocatalytic-based immunotherapies for sepsis and related inflammatory diseases.

Role of LncRNAs in the Pathogenesis of Sepsis and their Clinical Significance.

Sepsis is a fatal organ dysfunction caused by the host's uncontrolled response to infection, with high morbidity and mortality. Early diagnosis and intervention are the most effective methods to reduce the mortality due to sepsis. However, there is still a lack of definite biomarkers or intervention targets for the diagnosis, evaluation, prognosis, and treatment of sepsis. Long non-coding RNAs (lncRNAs) are a type of noncoding transcript with a length ranging from 200 to 100,000 nucleotides. LncRNAs mainly locate in the cytoplasm and nucleus and participate in various signaling pathways related to inflammatory reactions and organ dysfunction. Recent studies have reported that lncRNAs are involved in regulating the pathophysiological process of sepsis. Some classical lncRNAs have been confirmed as promising biomarkers to evaluate the severity and prognosis of sepsis. This review summarizes the mechanical studies on lncRNAs in sepsis-induced acute lung, kidney, myocardial, and liver injuries, analyzes the role of lncRNAs in the pathogenesis of sepsis, and explores the possibility of lncRNAs as potential biomarkers and intervention targets for sepsis-induced multiple organ dysfunction.

CD40L-Activated DC Promotes Th17 Differentiation and Inhibits Th2 Differentiation in Sepsis-Induced Lung Injury via cGAS-STING Signaling.

Immune hemostasis due to an infection plays a vital role in sepsis-induced multiple organ dysfunction. Dendritic cells (DC) and T helper (Th) cells are the key members of the immune system maintaining immune homeostasis. This study aimed to explore the effect and mechanism of CD40L on the activation of DC and activated DC-induced Th2/Th17 differentiation. A CD40L knockout and cecal ligation and puncture (CLP) mouse model was established via cecal ligation. HE staining was used to evaluate the pathological changes. The gene expressions were studied using quantitative real-time polymerase chain reaction (qRT-PCR), while a transwell system was used to perform the co-culture of DC and T-cells. Flow cytometry was performed to detect the subtype of T and DC cells. ELISA was used to assess the amount of inflammatory factors. CD40L was highly expressed in the plasma of CLP mice. Knock out of CD40L inhibited the activation of DC cell and Th17 differentiation while promoting the Th2 differentiation. The mechanistic investigations revealed that CD40L promoted the activation of cGAS-STING pathway. Rescue experiments indicated that CD40L mediated DC activation via cGAS-STING signaling. Moreover, co-culturing of CD and CD+4 T-cells demonstrated that silencing of CD40L in DC suppressed the DC activation and inhibited Th17 differentiation while promoting Th2 differentiation. These findings revealed a relationship between CD40L, DC activation, and Th2/Th17 differentiation balance in sepsis-induced acute lung injury for the first time. These findings are envisaged to provide novel molecular targets for sepsis-induced lung injury treatment.

Proteome characterization of liver-kidney comorbidity after microbial sepsis.

Sepsis is a life-threatening condition that occurs when the body responds to an infection but subsequently triggers widespread inflammation and impaired blood flow. These pathologic responses can rapidly cause multiple organ dysfunction or failure either one by one or simultaneously. The fundamental common mechanisms involved in sepsis-induced multiple organ dysfunction remain unclear. Here, employing quantitative global and phosphoproteomics, we examine the liver's temporal proteome and phosphoproteome changes after moderate sepsis induced by cecum ligation and puncture. In total, 4593 global proteins and 1186 phosphoproteins according to 3275 phosphosites were identified. To characterize the liver-kidney comorbidity after sepsis, we developed a mathematical model and performed cross-analyses of liver and kidney proteome data obtained from the same set of mice. Beyond immune response, we showed the commonly disturbed pathways and key regulators of the liver-kidney comorbidity are linked to energy metabolism and consumption. Our data provide open resources to understand the communication between the liver and kidney as they work to fight infection and maintain homeostasis.

Suppression by central adenosine A3 receptors of the cholinergic defense against cardiovascular aberrations of sepsis: role of PI3K/MAPKs/NFκB signaling.

Introduction: Despite the established role of peripheral adenosine receptors in sepsis-induced organ dysfunction, little or no data is available on the interaction of central adenosine receptors with sepsis. The current study tested the hypothesis that central adenosine A3 receptors (A3ARs) modulate the cardiovascular aberrations and neuroinflammation triggered by sepsis and their counteraction by the cholinergic antiinflammatory pathway. Methods: Sepsis was induced by cecal ligation and puncture (CLP) in rats pre-instrumented with femoral and intracisternal (i.c.) catheters for hemodynamic monitoring and central drug administration, respectively. Results: The CLP-induced hypotension, reduction in overall heart rate variability (HRV) and sympathovagal imbalance towards parasympathetic predominance were abolished by i.v. nicotine (100μg/kg) or i.c. VUF5574 (A3AR antagonist, 2µg/rat). In addition, the selective A3AR agonist, 3-iodobenzyl-5'-N-methylcarboxamidoadenosine IB-MECA, 4µg/rat, i.c.) exaggerated the hypotension and cardiac autonomic dysfunction induced by sepsis and opposed the favorable nicotine actions against these septic manifestations. Immunohistochemically, IB-MECA abolished the nicotine-mediated downregulation of NFκB and NOX2 expression in rostral ventrolateral medullary areas (RVLM) of brainstem of septic rats. The inhibitory actions of IB-MECA on nicotine responses disappeared after i.c. administration of PD98059 (MAPK-ERK inhibitor), SP600125 (MAPK-JNK inhibitor) or wortmannin (PI3K inhibitor). Moreover, infliximab (TNFα inhibitor) eliminated the IB-MECA-induced rises in RVLM-NFκB expression and falls in HRV, but not blood pressure. Conclusion: Central PI3K/MAPKs pathway mediates the A3AR counteraction of cholinergic defenses against cardiovascular and neuroinflammatory aberrations in sepsis.

Extracorporeal Blood Treatment Using Functional Magnetic Nanoclusters Mitigates Organ Dysfunction of Sepsis in Swine.

Mitigating sepsis-induced severe organ dysfunction with magnetic nanoparticles has shown remarkable advances in extracorporeal blood treatment. Nevertheless, treating large septic animals remains challenging due to insufficient magnetic separation at rapid blood flow rates (>6 L h-1) and limited incubation time in an extracorporeal circuit. Herein, superparamagnetic nanoclusters (SPNCs) coated with red blood cell (RBC) membranes are developed, which promptly capture and magnetically separate a wide range of pathogens at high blood flow rates in a swine sepsis model. The SPNCs exhibited an ultranarrow size distribution of clustered iron oxide nanocrystals and exceptionally high saturation magnetization (≈ 90 emu g-1) close to that of bulk magnetite. It is also revealed that CD47 on the RBCs allows the RBC-SPNCs to remain at a consistent concentration in the blood by evading innate immunity. The uniform size distribution of the RBC-SPNCs greatly enhances their effectiveness in eradicating various pathogenic materials in extracorporeal blood. The use of RBC-SPNCs for extracorporeal treatment of swine infected with multidrug-resistant E. coli is validated and found that severe bacteremic sepsis-induced organ dysfunction is significantly mitigated after 12 h. The findings highlight the potential application of RBC-SPNCs for extracorporeal therapy of severe sepsis in large animal models and potentially humans.

Extracellular Vesicles Derived from Human Adipose-Derived Mesenchymal Stem Cells Alleviate Sepsis-Induced Acute Lung Injury through a MicroRNA-150-5p-Dependent Mechanism.

Extracellular vesicles (EVs) derived from human adipose mesenchymal stem cells (hADSCs) may exert a therapeutic benefit in alleviating sepsis-induced organ dysfunction by delivering cargos that include RNAs and proteins to target cells. The current study aims to explore the protective effect of miR-150-5p delivered by hADSC-EVs on sepsis-induced acute lung injury (ALI). We noted low expression of miR-150-5p in plasma and bronchoalveolar lavage fluid samples from patients with sepsis-induced ALI. The hADSC-EVs were isolated and subsequently cocultured with macrophages. It was established that hADSC-EVs transferred miR-150-5p to macrophages, where miR-150-5p targeted HMGA2 to inhibit its expression and, consequently, inactivated the MAPK pathway. This effect contributed to the promotion of M2 polarization of macrophages and the inhibition of proinflammatory cytokines. Further, mice were made septic by cecal ligation and puncture in vivo and treated with hADSC-EVs to elucidate the effect of hADSC-EVs on sepsis-induced ALI. The in vivo experimental results confirmed a suppressive role of hADSC-EVs in sepsis-induced ALI. Our findings suggest that hADSC-EV-mediated transfer of miR-150-5p may be a novel mechanism underlying the paracrine effects of hADSC-EVs on the M2 polarization of macrophages in sepsis-induced ALI.

Novel insights into the regulatory role of N6-methyladenosine methylation modified autophagy in sepsis.

Sepsis is defined as a life-threatening organ dysfunction caused by a dysregulated host response to infection. It is characterized by high morbidity and mortality and one of the major diseases that seriously hang over global human health. Autophagy is a crucial regulator in the complicated pathophysiological processes of sepsis. The activation of autophagy is known to be of great significance for protecting sepsis induced organ dysfunction. Recent research has demonstrated that N6-methyladenosine (m6A) methylation is a well-known post-transcriptional RNA modification that controls epigenetic and gene expression as well as a number of biological processes in sepsis. In addition, m6A affects the stability, export, splicing and translation of transcripts involved in the autophagic process. Although it has been suggested that m6A methylation regulates the biological metabolic processes of autophagy and is more frequently seen in the progression of sepsis pathogenesis, the underlying molecular mechanisms of m6A-modified autophagy in sepsis have not been thoroughly elucidated. The present article fills this gap by providing an epigenetic review of the processes of m6A-modified autophagy in sepsis and its potential role in the development of novel therapeutics.

Pediatric Sepsis Diagnosis, Management, and Sub-phenotypes.

Sepsis and septic shock are major causes of morbidity, mortality, and health care costs for children worldwide, including >3 million deaths annually and, among survivors, risk for new or worsening functional impairments, including reduced quality of life, new respiratory, nutritional, or technological assistance, and recurrent severe infections. Advances in understanding sepsis pathophysiology highlight a need to update the definition and diagnostic criteria for pediatric sepsis and septic shock, whereas new data support an increasing role for automated screening algorithms and biomarker combinations to assist earlier recognition. Once sepsis or septic shock is suspected, attention to prompt initiation of broad-spectrum empiric antimicrobial therapy, fluid resuscitation, and vasoactive medications remain key components to initial management with several new and ongoing studies offering new insights into how to optimize this approach. Ultimately, a key goal is for screening to encompass as many children as possible at risk for sepsis and trigger early treatment without increasing unnecessary broad-spectrum antibiotics and preventable hospitalizations. Although the role for adjunctive treatment with corticosteroids and other metabolic therapies remains incompletely defined, ongoing studies will soon offer updated guidance for optimal use. Finally, we are increasingly moving toward an era in which precision therapeutics will bring novel strategies to improve outcomes, especially for the subset of children with sepsis-induced multiple organ dysfunction syndrome and sepsis subphenotypes for whom antibiotics, fluid, vasoactive medications, and supportive care remain insufficient.

Protective effects of tanshinone ⅡA on sepsis-induced multiple organ dysfunction: a literature review.

TanshinoneⅡA (TanⅡA) is a noteworthy lipophilic diterpene compound derived from the dried roots of the Traditional Chinese Medicine Danshen () that has various pharmacological properties, including anti-inflammatory, antibacterial, and antioxidative effects. Sepsis is a life-threatening organ dysfunction induced by a dysregulated host response to infection. Recently, increasing attention has been paid to sepsis-induced dysfunction of the intestine, car-diovascular system, lungs, kidneys, liver, and other organs. Experimental studies have shown that TanⅡA has therapeutic potential for sepsis-induced organ dysfunction owing to its anti-inflammatory, anti-apoptotic and regulatory effects on multiple signalling pathways. The purpose of this article is to evaluate the potential multiorgan protective effects of TanⅡA in sepsis.

Baricitinib protects mice from sepsis-induced cardiac dysfunction and multiple-organ failure.

Sepsis is one of the major complications of surgery resulting in high morbidity and mortality, but there are no specific therapies for sepsis-induced organ dysfunction. Data obtained under Gene Expression Omnibus accession GSE131761 were re-analyzed and showed an increased gene expression of Janus Kinase 2 (JAK2) and Signal Transducer and Activator of Transcription 3 (STAT3) in the whole blood of post-operative septic patients. Based on these results, we hypothesized that JAK/STAT activation may contribute to the pathophysiology of septic shock and, hence, investigated the effects of baricitinib (JAK1/JAK2 inhibitor) on sepsis-induced cardiac dysfunction and multiple-organ failure (MOF). In a mouse model of post-trauma sepsis induced by midline laparotomy and cecal ligation and puncture (CLP), 10-week-old male (n=32) and female (n=32) C57BL/6 mice received baricitinib (1mg/kg; i.p.) or vehicle at 1h or 3h post-surgery. Cardiac function was assessed at 24h post-CLP by echocardiography in vivo, and the degree of MOF was analyzed by determination of biomarkers in the serum. The potential mechanism underlying both the cardiac dysfunction and the effect of baricitinib was analyzed by western blot analysis in the heart. Trauma and subsequent sepsis significantly depressed the cardiac function and induced multiple-organ failure, associated with an increase in the activation of JAK2/STAT3, NLRP3 inflammasome and NF- κβ pathways in the heart of both male and female animals. These pathways were inhibited by the administration of baricitinib post the onset of sepsis. Moreover, treatment with baricitinib at 1h or 3h post-CLP protected mice from sepsis-induced cardiac injury and multiple-organ failure. Thus, baricitinib may be repurposed for trauma-associated sepsis.

High-dose ascorbic acid potentiates immune modulation through STAT1 phosphorylation inhibition and negative regulation of PD-L1 in experimental sepsis.

Sepsis is a complex, multifactorial syndrome characterized by a dysregulated host response to infection, leading to severe organ dysfunction and high mortality rates among critically ill patients. Hypovitaminosis C and vitamin C deficiency are frequently observed in septic patients, prompting interest in the potential therapeutic role of ascorbic acid. Although intravenous administration of ascorbic acid has been investigated in multiple clinical trials for sepsis treatment, the specific immunomodulatory mechanisms underlying its effects remain elusive. This study aimed to investigate the protective effects of high-dose ascorbic acid on experimental sepsis. Results show that intravenous administration of high-dose ascorbic acid (250mg/kg) attenuated sepsis-induced organ dysfunctions in a cecal ligation and puncture (CLP)-induced septic mouse model. Ascorbic acid improved splenic cell apoptosis and increased the number of CD3+ T cells in septic mice induced by CLP. Furthermore, ascorbic acid downregulated PD-L1 expression in livers, reduced PD-1 expression in spleens, and inhibited the phosphorylation of STAT1 at Y701 in multiple organs of CLP-induced septic mice. The in vitro experiments also revealed that 800μM ascorbic acid suppressed STAT1 phosphorylation and inhibited lipopolysaccharide (LPS) and IFN-γ-induced PD-L1 expression in macrophages. These findings suggest that ascorbic acid prevents sepsis-associated organ dysfunction through the p-STAT1/PD-L1 signaling pathway. Our study provides new insights into the potential therapeutic use of ascorbic acid in sepsis.

The Design of Nested Adaptive Clinical Trials of Multiple Organ Dysfunction Syndrome Children in a Single Study.

Describe the statistical design of the Personalized Immunomodulation in Sepsis-induced Multiple Organ Dysfunction Syndrome (MODS) (PRECISE) study. Children with sepsis-induced MODS undergo real-time immune testing followed by assignment to an immunophenotype-specific study cohort. Interventional cohorts include the granulocyte macrophage-colony stimulating factor (GM-CSF) for the Reversal of Immunoparalysis in Pediatric Sepsis-induced MODS (GRACE)-2 trial, which uses the drug GM-CSF (or placebo) to reverse immunoparalysis; and the Targeted Reversal of Inflammation in Pediatric Sepsis-induced MODS (TRIPS) trial, which uses the drug anakinra (or placebo) to reverse systemic inflammation. Both trials have adaptive components and use a statistical framework in which frequent data monitoring assesses futility and efficacy, allowing potentially earlier stopping than traditional approaches. Prespecified simulation-based stopping boundaries are customized to each trial to preserve an overall one-sided type I error rate. The TRIPS trial also uses response-adaptive randomization, updating randomization allocation proportions to favor active arms that appear more efficacious based on accumulating data. Twenty-four U.S. academic PICUs. Septic children with specific immunologic derangements during ongoing dysfunction of at least two organs. The GRACE-2 trial compares GM-CSF and placebo in children with immunoparalysis. The TRIPS trial compares four different doses of anakinra to placebo in children with moderate to severe systemic inflammation. Both trials assess primary efficacy using the sum of the daily pediatric logistic organ dysfunction-2 score over 28 days. Ranked summed scores, with mortality assigned the worst possible value, are compared between arms using the Wilcoxon Rank Sum test (GRACE-2) and a dose-response curve (TRIPS). We present simulation-based operating characteristics under several scenarios to demonstrate the behavior of the adaptive design. The adaptive design incorporates innovative statistical features that allow for multiple active arms to be compared with placebo based on a child's personal immunophenotype. The design increases power and provides optimal operating characteristics compared with traditional conservative methods.

Plantamajoside alleviates acute sepsis-induced organ dysfunction through inhibiting the TRAF6/NF-κB axis

Context Plantamajoside (PMS) possesses rich pharmacological characteristics that have been applied to remedy dozens of diseases. However, the understanding of PMS in sepsis remains insufficient. Objective Role of PMS in sepsis-regulated organ dysfunction and potential mechanisms were investigated. Materials and methods Thirty C57BL/6 male mice were adaptive fed for three days and used to establish acute sepsis model by caecal ligation and perforation (CLP). These experimental mice were divided into Sham, CLP, CLP + 25 mg PMS/kg body weight (PMS/kg), CLP + 50 mg PMS/kg and CLP + 100 mg PMS/kg (n = 6). The pathological and apoptotic changes of lung, liver and heart tissues were observed via HE and TUNEL staining. The injury-related factors of lung, liver and heart were detected by corresponding kits. ELISA and qRT-PCR were applied to assess IL-6/TNF-α/IL-1β levels. Apoptosis-related and TRAF6/NF-κB-related proteins were determined using Western blotting. Results All doses of PMS enhanced the survival rates in the sepsis-induced mouse model. PMS remitted sepsis-mediated lung, liver and heart injury through prohibiting MPO/BALF (70.4%/85.6%), AST/ALT (74.7%/62.7%) and CK-MB/CK (62.3%/68.9%) levels. Moreover, the apoptosis index (lung 61.9%, liver 50.2%, heart 55.7% reduction) and IL-6/TNF-α/IL-1β levels were suppressed by PMS. Furthermore, PMS lowered TRAF6 and p-NF-κB p65 levels, whereas TRAF6 overexpression reversed the protective influences of PMS in organ injury, apoptosis and inflammation triggered by sepsis. Discussion and conclusions PMS suppressed sepsis-induced organ dysfunction by regulating the TRAF6/NF-κB axis, and PMS treatment may be considered as a novel strategy for sepsis-caused damage in future.

Disseminated intravascular coagulation phenotype is regulated by the TRPM7 channel during sepsis

BackgroundSepsis is an uncontrolled inflammatory response against a systemic infection that results in elevated mortality, mainly induced by bacterial products known as endotoxins, producing endotoxemia. Disseminated intravascular coagulation (DIC) is frequently observed in septic patients and is associated with organ failure and death. Sepsis activates endothelial cells (ECs), promoting a prothrombotic phenotype contributing to DIC. Ion channel-mediated calcium permeability participates in coagulation. The transient reception potential melastatin 7 (TRPM7) non-selective divalent cation channel that also contains an α-kinase domain, which is permeable to divalent cations including Ca2+, regulates endotoxin-stimulated calcium permeability in ECs and is associated with increased mortality in septic patients. However, whether endothelial TRPM7 mediates endotoxemia-induced coagulation is not known. Therefore, our aim was to examine if TRPM7 mediates coagulation during endotoxemia.ResultsThe results showed that TRPM7 regulated endotoxin-induced platelet and neutrophil adhesion to ECs, dependent on the TRPM7 ion channel activity and by the α-kinase function. Endotoxic animals showed that TRPM7 mediated neutrophil rolling on blood vessels and intravascular coagulation. TRPM7 mediated the increased expression of the adhesion proteins, von Willebrand factor (vWF), intercellular adhesion molecule 1 (ICAM-1), and P-selectin, which were also mediated by the TRPM7 α-kinase function. Notably, endotoxin-induced expression of vWF, ICAM-1 and P-selectin were required for endotoxin-induced platelet and neutrophil adhesion to ECs. Endotoxemic rats showed increased endothelial TRPM7 expression associated with a procoagulant phenotype, liver and kidney dysfunction, increased death events and an increased relative risk of death. Interestingly, circulating ECs (CECs) from septic shock patients (SSPs) showed increased TRPM7 expression associated with increased DIC scores and decreased survival times. Additionally, SSPs with a high expression of TRPM7 in CECs showed increased mortality and relative risk of death. Notably, CECs from SSPs showed significant results from the AUROC analyses for predicting mortality in SSPs that were better than the Acute Physiology and Chronic Health Evaluation II (APACHE II) and the Sequential Organ Failure Assessment (SOFA) scores.ConclusionsOur study demonstrates that sepsis-induced DIC is mediated by TRPM7 in ECs. TRPM7 ion channel activity and α-kinase function are required by DIC-mediated sepsis-induced organ dysfunction and its expression are associated with increased mortality during sepsis. TRPM7 appears as a new prognostic biomarker to predict mortality associated to DIC in SSPs, and as a novel target for drug development against DIC during infectious inflammatory diseases.

Calcitonin gene-related peptide ameliorates sepsis-induced intestinal injury by suppressing NLRP3 inflammasome activation

Intestinal damage has long been viewed as the primary cause of sepsis-induced multiple organ dysfunction syndrome (MODS). Previous studies have demonstrated that calcitonin gene-related peptide (CGRP) exhibits anti-inflammatory and protective effects in mice exposed to endotoxin. This study investigated whether CGRP protects against sepsis-induced intestinal damage and its underlying mechanisms. Using a murine caecal ligation and puncture (CLP) model, we observed elevated serum and intestinal CGRP levels in septic mice. CGRP knockout (KO) mice showed more severe intestinal barrier damage, excessive NLRP3 inflammasome activation and higher levels of inflammation. In vitro, we used lipopolysaccharide (LPS) and adenosine triphosphate (ATP) to activate the NLRP3 inflammasome in MODE-K murine intestinal epithelial cells. CGRP inhibited NF-κB pathway activation; prevented ASC assembly and ROS accumulation; significantly decreased NLRP3, Caspase-1 p10, and IL-1β levels and LDH release; and increased cell viability. Treatment with an IL-1β inhibitor or CGRP suppressed p38 MAPK and ERK1/2 pathway activation and increased ZO-1 and Occludin protein levels in LPS+ATP-treated MODE-K cells. Finally, we used the CGRP upstream agonist drug rutaecarpine (RUT) to control endogenous CGRP release in mice, and this drug demonstrated good therapeutic effects on septic intestinal injury. In conclusion, our results suggest that CGRP ameliorates sepsis-induced intestinal damage, providing valuable insights for drug development.

Orai1 overexpression improves sepsis-induced T-lymphocyte immunosuppression and acute organ dysfunction in mice

Immune paralysis induced by sepsis, especially dysfunction of CD4+ T cells, leads to an increased risk of infection. In sepsis, abnormal differentiation of T lymphocytes is associated with multiorgan dysfunction syndrome. In T lymphocytes, the Orai1/nuclear factor of activated T Cells (NFAT) pathway is a critical mediator of infection, inflammation, and autoimmunity. In this study, we confirmed immunosuppression of splenic CD4+ T cells and abnormal differentiation of T lymphocytes in septic mice. Furthermore, we found that the Orai1/NFAT signaling pathway was inhibited in septic mice; however, the overexpression of Orai1 not only improved immune function of T cells in sepsis but also reduced the mortality and organ damage in septic mice. Moreover, the overexpression of Orai1 could reverse the increases in the numbers of T regulatory and T helper 17 cells in septic mice. These data suggest that the Orai1-mediated NFAT signaling pathway can improve sepsis-induced T-lymphocyte immunosuppression and acute organ dysfunction.

Quercetin protects against LPS-induced lung injury in mice via SIRT1-mediated suppression of PKM2 nuclear accumulation

The role of NOD-like receptor protein 3 (NLRP3)-mediated macrophages pyroptosis in acute lung injury (ALI) is well-established. Quercetin (Que) is a natural bioflavonoid compound with anti-inflammatory and antioxidative properties that reportedly inhibits the NLRP3 inflammasome in sepsis-induced organ dysfunctions such as ALI. However, the mechanism underlying the inhibitory effect of quercetin on NLRP3 activation remains unclear. In this study, we established an endotoxin-induced ALI mouse model with an in vitro LPS challenge. We demonstrated that the administration of quercetin could significantly reduce pulmonary injury and decrease the production of pro-inflammatory cytokines. Moreover, we found that quercetin could inhibit the activation of the NLRP3 inflammasome by suppressing the nuclear accumulation of PKM2 and increasing SIRT1 levels. Importantly, treatment with SRT1720 (a specific SIRT1 activator) could inhibit the nuclear accumulation of PKM2 and the activation of NLRP3. Besides, preventing PKM2 dimerization with ML265 yielded an anti-inflammatory effect, similar to findings observed for SRT1720. In addition, we found that SIRT1 silencing or inhibition by EX527 could increase NLRP3 activation and nuclear accumulation of PKM2 and override quercetin-mediated anti-inflammatory activity. These findings indicated that quercetin could downregulate NLRP3 inflammasome activation by inhibiting the nuclear accumulation of PKM2 and upregulating SIRT1 expression, expanding the treatment landscape for ARDS.

ICOS-Fc as innovative immunomodulatory approach to counteract inflammation and organ injury in sepsis.

Inducible T cell co-stimulator (ICOS), an immune checkpoint protein expressed on activated T cells and its unique ligand, ICOSL, which is expressed on antigen-presenting cells and non-hematopoietic cells, have been extensively investigated in the immune response. Recent findings showed that a soluble recombinant form of ICOS (ICOS-Fc) can act as an innovative immunomodulatory drug as both antagonist of ICOS and agonist of ICOSL, modulating cytokine release and cell migration to inflamed tissues. Although the ICOS-ICOSL pathway has been poorly investigated in the septic context, a few studies have reported that septic patients have reduced ICOS expression in whole blood and increased serum levels of osteopontin (OPN), that is another ligand of ICOSL. Thus, we investigated the pathological role of the ICOS-ICOSL axis in the context of sepsis and the potential protective effects of its immunomodulation by administering ICOS-Fc in a murine model of sepsis. Polymicrobial sepsis was induced by cecal ligation and puncture (CLP) in five-month-old male wild-type (WT) C57BL/6, ICOS-/-, ICOSL-/- and OPN-/- mice. One hour after the surgical procedure, either CLP or Sham (control) mice were randomly assigned to receive once ICOS-Fc, F119SICOS-Fc, a mutated form uncapable to bind ICOSL, or vehicle intravenously. Organs and plasma were collected 24 h after surgery for analyses. When compared to Sham mice, WT mice that underwent CLP developed within 24 h a higher clinical severity score, a reduced body temperature, an increase in plasma cytokines (TNF-α, IL-1β, IL-6, IFN-γ and IL-10), liver injury (AST and ALT) and kidney (creatinine and urea) dysfunction. Administration of ICOS-Fc to WT CLP mice reduced all of these abnormalities caused by sepsis. Similar beneficial effects were not seen in CLP-mice treated with F119SICOS-Fc. Treatment of CLP-mice with ICOS-Fc also attenuated the sepsis-induced local activation of FAK, P38 MAPK and NLRP3 inflammasome. ICOS-Fc seemed to act at both sides of the ICOS-ICOSL interaction, as the protective effect was lost in septic knockout mice for the ICOS or ICOSL genes, whereas it was maintained in OPN knockout mice. Collectively, our data show the beneficial effects of pharmacological modulation of the ICOS-ICOSL pathway in counteracting the sepsis-induced inflammation and organ dysfunction.