Protective Effects of Inhibition of Mitochondrial Fission on Organ Function After Sepsis

Protective Effects of Mdivi-1 on Cognition Disturbance Following Sepsis in Mice via Alleviating Microglia Activation and Polarization

BACKGROUND

Neuroinflammation is one of the essential pathogeneses of cognitive damage suffering from sepsis-associated encephalopathy (SAE). Lots of evidences showed the microglia presented mitochondrial fragmentation during SAE. This study investigated the protective effects and novel mechanisms of inhibiting microglia mitochondrial fragmentation via mitochondrial division inhibitor 1 (Mdivi-1) on cognitive damage in SAE.

METHODS

The SAE model was performed by cecal ligation and puncture (CLP), and Mdivi-1 was administrated via intraperitoneal injection. Morris water maze was performed to assess cognitive function. Mitochondrial morphology was observed by electron microscope or MitoTracker staining. The qRT-PCR, immunofluorescence staining, and western blots were used to detect the inflammatory factors and protein content, respectively. Flow cytometry was used to detect the polarization of hippocampal microglia. Bioinformatics analysis was used to verify hypotheses.

RESULTS

Mdivi-1 administration alleviated sepsis-induced mitochondrial fragmentation, microglia activation, polarization, and cognitive damage. The mechanisms study showed neuroinflammation and oxidative stress were suppressed via NF-κB and Keap1/Nrf2/HO-1 pathways following Mdivi-1 administration; meanwhile, pyroptosis in microglia was reduced, which was associated with enhanced autophagosome formation via p62 elevation following Mdivi-1 administration.

CONCLUSION

Inhibition of microglia mitochondrial fragmentation is beneficial to SAE cognitive disturbance, the mechanisms are related to alleviating neuroinflammation, oxidative stress, and pyroptosis.

Nano Acacetin Mitigates Intestinal Mucosal Injury in Sepsis Rats by Protecting Mitochondrial Function and Regulating TRX1 to Inhibit the NLRP3 Pyroptosis Pathway

Background

Acacetin (AC) is a flavonoid compound with antiperoxidant, anti-inflammatory, and antiplasmodial activity. However, the solubility of AC is poor and nano acacetin (Nano AC) was synthesized. The intestinal mucosal barrier is impaired in sepsis rats, and the protective effects and mechanism of AC and Nano AC on the intestinal mucosal barrier are unclear.

Methods

Cecal ligation and perforation (CLP) was used to induce sepsis in rats, and lipopolysaccharide (LPS)-stimulated intestinal epithelial cells were used to observe the effects of AC and our synthesized Nano AC on the amelioration of intestinal mucosal damage. The molecular docking technique was used to predict the binding energy of AC to thioredoxin reductase 1 (TRX1) signaling pathway proteins. TRX1 inhibitor (PX-12) was employed to elucidate the protective signaling pathway of Nano AC in LPS-stimulated intestinal epithelial cells.

Results

Our synthesized Nano AC, with an average particle size of 17.18 ± 0.48 nm and an uptake rate of 95% in intestinal epithelial cells. The maximum binding capacity of AC to TRX1 was -6.82 kcal/mol, supporting the hypothesis that TRX1 is a potential target of AC. AC and Nano AC ameliorated the survival rate, intestinal mucosal damage score, pathological morphology, hepatic and renal function, and myocardial troponin levels, decreased serum levels of pyroptosis-related factors, upregulated TRX1, down-regulated NOD-like receptor protein 3 inflammasome (NLRP3), cysteinyl aspartate specific proteinase-11 (Caspase-11), Gasdermin D (GSDMD) in sepsis rats. They improved mitochondrial morphology and mitochondrial reactive oxygen species (ROS) levels, reduced pyroptosis levels, and upregulated TRX1, which adjusted NLRP3/ Caspase-11/ GSDMD signaling pathway in LPS-stimulated intestinal epithelial cells. Moreover, Nano AC was more effective.

Conclusion

AC and Nano-AC can inhibit the NLRP3/Caspase-11/GSDMD signaling pathway by upregulating TRX1 to ameliorate intestinal mucosal injury in sepsis rats, and the effect of Nano AC is more prominent.

Notoginsenoside R1 improves intestinal microvascular functioning in sepsis by targeting Drp1-mediated mitochondrial quality imbalance

CONTEXT

Sepsis can result in critical organ failure, and notoginsenoside R1 (NGR1) offers mitochondrial protection.

OBJECTIVE

To determine whether NGR1 improves organ function and prognosis after sepsis by protecting mitochondrial quality.

MATERIALS AND METHODS

A sepsis model was established in C57BL/6 mice using cecum ligation puncture (CLP) and an in vitro model with lipopolysaccharide (LPS, 10 µg/mL)-stimulated primary intestinal microvascular endothelial cells (IMVECs) and then determine NGR1's safe dosage. Groups for each model were: in vivo-a control group, a CLP-induced sepsis group, and a CLP + NGR1 treatment group (30 mg/kg/d for 3 d); in vitro-a control group, a LPS-induced sepsis group, and a LPS + NGR1 treatment group (4 μM for 30 min). NGR1's effects on survival, intestinal function, mitochondrial quality, and mitochondrial dynamic-related protein (Drp1) were evaluated.

RESULTS

Sepsis resulted in approximately 60% mortality within 7 days post-CLP, with significant reductions in intestinal microvascular perfusion and increases in vascular leakage. Severe mitochondrial quality imbalance was observed in IMVECs. NGR1 (IC50 is 854.1 μM at 30 min) targeted Drp1, inhibiting mitochondrial translocation, preventing mitochondrial fragmentation and restoring IMVEC morphology and function, thus protecting against intestinal barrier dysfunction, vascular permeability, microcirculatory flow, and improving sepsis prognosis.

DISCUSSION AND CONCLUSIONS

Drp1-mediated mitochondrial quality imbalance is a potential therapeutic target for sepsis. Small molecule natural drugs like NGR1 targeting Drp1 may offer new directions for organ protection following sepsis. Future research should focus on clinical trials to evaluate NGR1's efficacy across various patient populations, potentially leading to novel treatments for sepsis.

Podocyte-targeted therapies - progress and future directions

Podocytes are the key target cells for injury across the spectrum of primary and secondary proteinuric kidney disorders, which account for up to 90% of cases of kidney failure worldwide. Seminal experimental and clinical studies have established a causative link between podocyte depletion and the magnitude of proteinuria in progressive glomerular disease. However, no substantial advances have been made in glomerular disease therapies, and the standard of care for podocytopathies relies on repurposed immunosuppressive drugs. The past two decades have seen a remarkable expansion in understanding of the mechanistic basis of podocyte injury, with prospects increasing for precision-based treatment approaches. Dozens of disease-causing genes with roles in the pathogenesis of clinical podocytopathies have been identified, as well as a number of putative glomerular permeability factors. These achievements, together with the identification of novel targets of podocyte injury, the development of potential approaches to harness the endogenous podocyte regenerative potential of progenitor cell populations, ongoing clinical trials of podocyte-specific pharmacological agents and the development of podocyte-directed drug delivery systems, contribute to an optimistic outlook for the future of glomerular disease therapy.

Mitochondrial dysfunction in sepsis: mechanisms and therapeutic perspectives

Sepsis is a severe medical condition characterized by a systemic inflammatory response, often culminating in multiple organ dysfunction and high mortality rates. In recent years, there has been a growing recognition of the pivotal role played by mitochondrial damage in driving the progression of sepsis. Various factors contribute to mitochondrial impairment during sepsis, encompassing mechanisms such as reactive nitrogen/oxygen species generation, mitophagy inhibition, mitochondrial dynamics change, and mitochondrial membrane permeabilization. Damaged mitochondria actively participate in shaping the inflammatory milieu by triggering key signaling pathways, including those mediated by Toll-like receptors, NOD-like receptors, and cyclic GMP-AMP synthase. Consequently, there has been a surge of interest in developing therapeutic strategies targeting mitochondria to mitigate septic pathogenesis. This review aims to delve into the intricate mechanisms underpinning mitochondrial dysfunction during sepsis and its significant impact on immune dysregulation. Moreover, we spotlight promising mitochondria-targeted interventions that have demonstrated therapeutic efficacy in preclinical sepsis models.

Molecular mechanisms of Sepsis attacking the immune system and solid organs

Remarkable progress has been achieved in sepsis treatment in recent times, the mortality rate of sepsis has experienced a gradual decline as a result of the prompt administration of antibiotics, fluid resuscitation, and the implementation of various therapies aimed at supporting multiple organ functions. However, there is still significant mortality and room for improvement. The mortality rate for septic patients, 22.5%, is still unacceptably high, accounting for 19.7% of all global deaths. Therefore, it is crucial to thoroughly comprehend the pathogenesis of sepsis in order to enhance clinical diagnosis and treatment methods. Here, we summarized classic mechanisms of sepsis progression, activation of signal pathways, mitochondrial quality control, imbalance of pro-and anti- inflammation response, diseminated intravascular coagulation (DIC), cell death, presented the latest research findings for each mechanism and identify potential therapeutic targets within each mechanism.

Targeting mitochondrial quality control: new therapeutic strategies for major diseases

Mitochondria play a crucial role in maintaining the normal physiological state of cells. Hence, ensuring mitochondrial quality control is imperative for the prevention and treatment of numerous diseases. Previous reviews on this topic have however been inconsistencies and lack of systematic organization. Therefore, this review aims to provide a comprehensive and systematic overview of mitochondrial quality control and explore the possibility of targeting the same for the treatment of major diseases. This review systematically summarizes three fundamental characteristics of mitochondrial quality control, including mitochondrial morphology and dynamics, function and metabolism, and protein expression and regulation. It also extensively examines how imbalances in mitochondrial quality are linked to major diseases, such as ischemia-hypoxia, inflammatory disorders, viral infections, metabolic dysregulations, degenerative conditions, and tumors. Additionally, the review explores innovative approaches to target mitochondrial quality control, including using small molecule drugs that regulate critical steps in maintaining mitochondrial quality, nanomolecular materials designed for precise targeting of mitochondria, and novel cellular therapies, such as vesicle therapy and mitochondrial transplantation. This review offers a novel perspective on comprehending the shared mechanisms underlying the occurrence and progression of major diseases and provides theoretical support and practical guidance for the clinical implementation of innovative therapeutic strategies that target mitochondrial quality control for treating major diseases.

Evolving Paradigms in Sepsis Management: A Narrative Review

Sepsis, a condition characterized by life-threatening organ dysfunction due to a dysregulated host response to infection, significantly impacts global health, with mortality rates varying widely across regions. Traditional therapeutic strategies that target hyperinflammation and immunosuppression have largely failed to improve outcomes, underscoring the need for innovative approaches. This review examines the development of therapeutic agents for sepsis, with a focus on clinical trials addressing hyperinflammation and immunosuppression. It highlights the frequent failures of these trials, explores the underlying reasons, and outlines current research efforts aimed at bridging the gap between theoretical advancements and clinical applications. Although personalized medicine and phenotypic categorization present promising directions, this review emphasizes the importance of understanding the complex pathogenesis of sepsis and developing targeted, effective therapies to enhance patient outcomes. By addressing the multifaceted nature of sepsis, future research can pave the way for more precise and individualized treatment strategies, ultimately improving the management and prognosis of sepsis patients.

ACE2 activation alleviates sepsis-induced cardiomyopathy by promoting MasR-Sirt1-mediated mitochondrial biogenesis

Sepsis-induced cardiomyopathy (SIC), caused by a dysregulated host response to infection, is a major contributor to high mortality. Angiotensin-converting enzyme 2 (ACE2), a crucial component of the renin-angiotensin system (RAS), has protective effects against several cardiovascular diseases, such as myocardial infarction and heart failure. However, the role of ACE2 in the pathogenesis of SIC and underlying mechanisms remain unknown. The present study was designed to examine the effects of ACE2 activation or inhibition on SIC in C57BL/6 mice. The ACE2 activator diminazene aceturate (DIZE) and ACE2 inhibitor MLN-4760 were applied for treatment. Myocardial function, inflammatory response, oxidative stress, apoptosis and mitochondrial biogenesis were investigated. Major assays were echocardiography, H&E staining, immunofluorescence staining, DHE staining, TUNEL staining, Western blot, qPCR analysis, ELISA and corresponding kits. We confirmed that ACE2 was markedly downregulated in septic heart tissues. Pharmacological activation of ACE2 by DIZE ameliorated cecal ligation puncture (CLP)-induced mortality, cardiac dysfunction, inflammatory response, oxidative stress and the cardiomyocyte apoptosis by promoting MasR-Sirt1-mediated mitochondrial biogenesis. In contrast, SIC was aggravated via inhibiting MasR-Sirt1-mediated mitochondrial biogenesis by the use of ACE2 inhibitor MLN-4760. Consequently, activation of ACE2 may protect against SIC by promoting MasR-Sirt1-mediated mitochondrial biogenesis.

Upregulation of PTPN1 aggravates endotoxemia-induced cardiac dysfunction through inhibiting mitophagy

OBJECTIVES

To investigate the role of protein tyrosine phosphatase non-receptor type 1 (PTPN1) in mitophagy during sepsis and its underlying mechanisms and determine the therapeutic potential of PTPN1 inhibitors in endotoxemia-induced cardiac dysfunction.

METHODS

A mouse model of endotoxemia was established by administering an intraperitoneal injection of lipopolysaccharide (LPS). The therapeutic effect of targeting PTPN1 was evaluated using its inhibitor Claramine (CLA). Mitochondrial structure and function as well as the expression of mitophagy-related proteins were evaluated. Rat H9c2 cardiomyocytes were exposed to mouse RAW264.7 macrophage-derived conditioned medium. Cryptotanshinone, a specific p-STAT3 (Y705) inhibitor, was used to confirm the role of STAT3 in PTPN1-mediated mitophagy following LPS exposure. Electrophoretic mobility shift and dual luciferase reporter assays were performed to discern the mechanisms by which STAT3 regulated the expression of PINK1 and PRKN.

RESULTS

CLA alleviated LPS-induced myocardial damage, cardiac dysfunction, and mitochondrial injury and dysfunction in the mouse heart. PTPN1 upregulation exacerbated LPS-induced mitochondrial injury and dysfunction in H9c2 cardiomyocytes, but inhibited LPS-induced mitophagy. LPS promoted the interaction between PTPN1 and STAT3 and reduced STAT3 phosphorylation at Tyr705 (Y705), which was required to inhibit mitophagy by PTPN1. Upon LPS stimulation, PTPN1 negatively regulated the transcription of PINK1 and PRKN through dephosphorylation of STAT3 at Y705. STAT3 regulated the transcription of PINK1 and PRKN by binding to STAT3-responsive elements in their promoters.

CONCLUSION

PTPN1 upregulation aggravates endotoxemia-induced cardiac dysfunction by impeding mitophagy through dephosphorylation of STAT3 at Y705 and negative regulation of PINK1 and PRKN transcription.

From Physiology to Pathology: The Role of Mitochondria in Acute Kidney Injuries and Chronic Kidney Diseases

Background

Renal diseases remain an increasing public health issue affecting millions of people. The kidney is a highly energetic organ that is rich in mitochondria. Numerous studies have demonstrated the important role of mitochondria in maintaining normal kidney function and in the pathogenesis of various renal diseases, including acute kidney injuries (AKIs) and chronic kidney diseases (CKDs).

Summary

Under physiological conditions, fine-tuning mitochondrial energy balance, mitochondrial dynamics (fission and fusion processes), mitophagy, and biogenesis maintain mitochondrial fitness. While under AKI and CKD conditions, disruption of mitochondrial energy metabolism leads to increased oxidative stress. In addition, mitochondrial dynamics shift to excessive mitochondrial fission, mitochondrial autophagy is impaired, and mitochondrial biogenesis is also compromised. These mitochondrial injuries regulate renal cellular functions either directly or indirectly. Mitochondria-targeted approaches, containing genetic (microRNAs) and pharmaceutical methods (mitochondria-targeting antioxidants, mitochondrial permeability pore inhibitors, mitochondrial fission inhibitors, and biogenesis activators), are emerging as important therapeutic strategies for AKIs and CKDs.

Key Messages

Mitochondria play a critical role in the pathogenesis of AKIs and CKDs. This review provides an updated overview of mitochondrial homeostasis under physiological conditions and the involvement of mitochondrial dysfunction in renal diseases. Finally, we summarize the current status of mitochondria-targeted strategies in attenuating renal diseases.

PROMOTING MITOCHONDRIAL DYNAMIC EQUILIBRIUM ATTENUATES SEPSIS-INDUCED ACUTE LUNG INJURY BY INHIBITING PROINFLAMMATORY POLARIZATION OF ALVEOLAR MACROPHAGES

ABSTRACT

Sepsis-induced acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) is characterized by widespread pulmonary inflammation and immune response, in which proinflammatory polarization of alveolar macrophages (AMs) plays an important role. Mitochondria are the key intracellular signaling platforms regulating immune cell responses. Moreover, accumulating evidence suggests that the mitochondrial dynamics of macrophages are imbalanced in sepsis and severe ALI/ARDS. However, the functional significance of mitochondrial dynamics of AMs in septic ALI/ARDS remains largely unknown, and whether it regulates the polarized phenotype of AMs is also unclear. Here, we demonstrated that the mitochondrial dynamics of AMs are imbalanced, manifested by impaired mitochondrial fusion, increased fission and mitochondrial cristae remodeling, both in septic models and ARDS patients. However, suppressing excessive mitochondrial fission with Mdivi-1 or promoting mitochondrial fusion with PM1 to maintain mitochondrial dynamic equilibrium in AMs could inhibit the polarization of AMs into proinflammatory phenotype and attenuate sepsis-induced ALI. These data suggest that mitochondrial dynamic imbalance mediates altered polarization of AMs and exacerbates sepsis-induced ALI. This study provides new insights into the underlying mechanisms of sepsis-induced ALI, suggesting the possibility of identifying future drug targets from the perspective of mitochondrial dynamics in AMs.

Understanding Post-Sepsis Syndrome: How Can Clinicians Help?

Sepsis is a global health challenge, with over 49 million cases annually. Recent medical advancements have increased in-hospital survival rates to approximately 80%, but the escalating incidence of sepsis, owing to an ageing population, rise in chronic diseases, and antibiotic resistance, have also increased the number of sepsis survivors. Subsequently, there is a growing prevalence of "post-sepsis syndrome" (PSS). This syndrome includes long-term physical, medical, cognitive, and psychological issues after recovering from sepsis. PSS puts survivors at risk for hospital readmission and is associated with a reduction in health- and life span, both at short and long term, after hospital discharge. Comprehensive understanding of PSS symptoms and causative factors is vital for developing optimal care for sepsis survivors, a task of prime importance for clinicians. This review aims to elucidate our current knowledge of PSS and its relevance in enhancing post-sepsis care provided by clinicians.

Mitochondrial dysfunction and mitophagy: crucial players in burn trauma and wound healing

Burn injuries are a significant cause of death worldwide, leading to systemic inflammation, multiple organ failure and sepsis. The progression of burn injury is explicitly correlated with mitochondrial homeostasis, which is disrupted by the hyperinflammation induced by burn injury, leading to mitochondrial dysfunction and cell death. Mitophagy plays a crucial role in maintaining cellular homeostasis by selectively removing damaged mitochondria. A growing body of evidence from various disease models suggest that pharmacological interventions targeting mitophagy could be a promising therapeutic strategy. Recent studies have shown that mitophagy plays a crucial role in wound healing and burn injury. Furthermore, chemicals targeting mitophagy have also been shown to improve wound recovery, highlighting the potential for novel therapeutic strategies based on an in-depth exploration of the molecular mechanisms regulating mitophagy and its association with skin wound healing.

Effects of Mdivi-1 on Extending the Golden Treatment Time following Hemorrhagic Shock in Hot Environment in Rats

It is found that a hot environment aggravates hemorrhagic shock-induced internal environment and organ dysfunction. Meanwhile mitochondria show over-fission. Whether inhibition of mitochondrial fission benefits from the early treatment of hemorrhagic shock under a hot environment is unclear. An uncontrolled hemorrhagic shock model in rats is used, and the effects of mitochondrial fission inhibitor mdivi-1 on mitochondrial function, organ function, and survival rate of rats are measured. The results show that 0.1-3 mg/kg mdivi-1 antagonizes hemorrhagic shock-induced mitochondrial fragment. In addition, mdivi-1 improves mitochondrial function, and alleviates hemorrhagic shock-induced oxidative stress and inflammation under a hot environment. Further studies show that 0.1-3 mg/kg Mdivi-1 reduces blood loss, and maintains a mean artery pressure (MAP) of 50-60 mmHg before bleeding-stops after hemorrhagic shock, compared with single Lactate Ringer's (LR) resuscitation. Notably, 1 mg/kg of Mdivi-1 extends the time of hypotensive resuscitation to 2-3 h. During 1 or 2 h of ligation, Mdivi-1 prolongs survival time and protects vital organ function by rescuing mitochondrial morphology and improving mitochondrial function. These results suggest Mdivi-1 is suitable for the early treatment of hemorrhagic shock under a hot environment and can extend the golden treatment time to 2-3 hour for hemorrhagic shock under a hot environment.

Secretory Factors from Calcium-Sensing Receptor-Activated SW872 Pre-Adipocytes Induce Cellular Senescence and A Mitochondrial Fragmentation-Mediated Inflammatory Response in HepG2 Cells

Adipose tissue inflammation in obesity has a deleterious impact on organs such as the liver, ultimately leading to their dysfunction. We have previously shown that activation of the calcium-sensing receptor (CaSR) in pre-adipocytes induces TNF-α and IL-1β expression and secretion; however, it is unknown whether these factors promote hepatocyte alterations, particularly promoting cell senescence and/or mitochondrial dysfunction. We generated conditioned medium (CM) from the pre-adipocyte cell line SW872 treated with either vehicle (CMveh) or the CaSR activator cinacalcet 2 µM (CMcin), in the absence or presence of the CaSR inhibitor calhex 231 10 µM (CMcin+cal). HepG2 cells were cultured with these CM for 120 h and then assessed for cell senescence and mitochondrial dysfunction. CMcin-treated cells showed increased SA-β-GAL staining, which was absent in TNF-α- and IL-1β-depleted CM. Compared to CMveh, CMcin arrested cell cycle, increased IL-1β and CCL2 mRNA, and induced p16 and p53 senescence markers, which was prevented by CMcin+cal. Crucial proteins for mitochondrial function, PGC-1α and OPA1, were decreased with CMcin treatment, concomitant with fragmentation of the mitochondrial network and decreased mitochondrial transmembrane potential. We conclude that pro-inflammatory cytokines TNF-α and IL-1β secreted by SW872 cells after CaSR activation promote cell senescence and mitochondrial dysfunction, which is mediated by mitochondrial fragmentation in HepG2 cells and whose effects were reversed with Mdivi-1. This investigation provides new evidence about the deleterious CaSR-induced communication between pre-adipocytes and liver cells, incorporating the mechanisms involved in cellular senescence.

The Mitochondrion: A Promising Target for Kidney Disease

Mitochondrial dysfunction is important in the pathogenesis of various kidney diseases and the mitochondria potentially serve as therapeutic targets necessitating further investigation. Alterations in mitochondrial biogenesis, imbalance between fusion and fission processes leading to mitochondrial fragmentation, oxidative stress, release of cytochrome c and mitochondrial DNA resulting in apoptosis, mitophagy, and defects in energy metabolism are the key pathophysiological mechanisms underlying the role of mitochondrial dysfunction in kidney diseases. Currently, various strategies target the mitochondria to improve kidney function and kidney treatment. The agents used in these strategies can be classified as biogenesis activators, fission inhibitors, antioxidants, mPTP inhibitors, and agents which enhance mitophagy and cardiolipin-protective drugs. Several glucose-lowering drugs, such as glucagon-like peptide-1 receptor agonists (GLP-1-RA) and sodium glucose co-transporter-2 (SGLT-2) inhibitors are also known to have influences on these mechanisms. In this review, we delineate the role of mitochondrial dysfunction in kidney disease, the current mitochondria-targeting treatment options affecting the kidneys and the future role of mitochondria in kidney pathology.

S100a8/a9 contributes to sepsis-induced cardiomyopathy by activating ERK1/2-Drp1-mediated mitochondrial fission and respiratory dysfunction

Sepsis-induced cardiomyopathy (SIC) is the main complication and a leading cause of death in intensive care units. S100a8/a9 is a calcium-binding protein that participates in various inflammatory diseases; however, its role in sepsis-induced cardiomyopathy and the underlying mechanism remains to be explored. Here, septic cardiomyopathy was induced with cecal ligation and puncture (CLP) in S100a9-knockout (KO) mice lacking the heterodimer S100a8/a9 or wild-type (WT) mice administered with an S100a9-specific inhibitor Paquinimod (Paq), which prevents the binding of S100a9 toTLR4. Our results showed that S100a8/a9 expression in the heart peaked 24 h following the CLP operation, declined at 48 h and returned to baseline at 72 h. Loss of S100a9 by knockout in mice protected against CLP-induced mortality, cardiac dysfunction, myocyte apoptosis, recruitment of Mac-2⁺ macrophages, superoxide production, and the expression of pro-inflammatory cytokines genes compared with WT mice. Moreover, S100a9-KO significantly attenuated CLP-induced activation of the ERK1/2-Drp1 (S616) pathway, excessive mitochondrial fission, and mitochondrial respiration dysfunction. In contrast, activation of ERK1/2 with its agonist tBHQ reversed the inhibitory effects of S100a9-knockout on CLP-induced cardiomyopathy and mitochondrial dysfunction. Finally, administration of Paq to WT mice markedly prevented the CLP-induced cardiomyopathy mitochondrial fission and dysfunction compared with vehicle control. In summary, our data reveal, for the first time, that S100a8/a9 plays a critical role in mediating SIC, presumably by activating TLR4-ERK1/2-Drp1-dependent mitochondrial fission and dysfunction and highlight that blockage of S100a8/a9 may be a promising therapeutic strategy to prevent SIC in patients with sepsis.

The Four Key Genes Participated in and Maintained Atrial Fibrillation Process via Reprogramming Lipid Metabolism in AF Patients

Atrial fibrillation (AF) is always in high incidence in the population, which can lead to serious complications. The structural and electrical remodeling of atrial muscle induced by inflammatory reaction or oxidative stress was considered as the major mechanism of AF. The treatment effect is not ideal based on current mechanisms. Recent studies demonstrated that lipid metabolism disorder of atrial muscle played an important role in the occurrence of AF. What key genes are involved is unclear. The purpose of the present study was to explore the lipid metabolism mechanism of AF. With the GEO database and the genomics of AF patients, metabolic related pathways and the key genes were analyzed. At the same time, the rat model of cecal ligation and puncture (CLP) was used to confirm the results. GSE 31821 and GSE 41177 were used as data sources, and the merged differentially expressed genes (DEGs) analysis showed that a total of 272 DEGs were found. GO annotation, KEGG, and gene set enrichment analysis (GSEA) showed that the fatty acid metabolism and the lipid biosynthetic process were involved in AF. Cholesterol biosynthesis, arachidonic acid metabolism, and the lipid droplet pathway were obviously increased in AF. Further analysis showed that four key genes, including ITGB1, HSP90AA1, CCND1, and HSPA8 participated in pathogenesis of AF regulating lipid biosynthesis. In CLP rats, metabolic profiling in the heart showed that the pyrimidine metabolism, the biosynthesis of unsaturated fatty acid metabolism, arginine and proline metabolism, and the fatty acid biosynthesis were involved. The four key genes were confirmed increased in the heart of CLP rats (p < 0.05 or 0.01). The results suggest that the lipid metabolism disorder participates in the occurrence of AF. ITGB1, HSP90AA1, CCND1, and HSPA8 are the key genes involved in the regulation of lipid biosynthesis.