Importance of Toll-like receptor 2 in mitochondrial dysfunction during polymicrobial sepsis

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.

Pattern-Recognition Receptors and Immunometabolic Reprogramming: What We Know and What to Explore

BACKGROUND

Evolutionarily, immune response is a complex mechanism that protects the host from internal and external threats. Pattern-recognition receptors (PRRs) recognize MAMPs, PAMPs, and DAMPs to initiate a protective pro-inflammatory immune response. PRRs are expressed on the cell membranes by TLR1, 2, 4, and 6 and in the cytosolic organelles by TLR3, 7, 8, and 9, NLRs, ALRs, and cGLRs. We know their downstream signaling pathways controlling immunoregulatory and pro-inflammatory immune response. However, the impact of PRRs on metabolic control of immune cells to control their pro- and anti-inflammatory activity has not been discussed extensively.

SUMMARY

Immune cell metabolism or immunometabolism critically determines immune cells' pro-inflammatory phenotype and function. The current article discusses immunometabolic reprogramming (IR) upon activation of different PRRs, such as TLRs, NLRs, cGLRs, and RLRs. The duration and type of PRR activated, species studied, and location of immune cells to specific organ are critical factors to determine the IR-induced immune response.

KEY MESSAGE

The work herein describes IR upon TLR, NLR, cGLR, and RLR activation. Understanding IR upon activating different PRRs is critical for designing better immune cell-specific immunotherapeutics and immunomodulators targeting inflammation and inflammatory diseases.

Toll-like receptor 2 deficiency ameliorates obesity-induced cardiomyopathy via inhibiting NF-κB signaling pathway

Growing evidence demonstrates that chronic low-grade inflammation, which is induced by high-fat diet (HFD) or saturated fatty acid, plays an important role in the obesity-induced cardiomyopathy (OIC) process. Moreover, obesity is associated with the activation of different inflammatory pathways, including nuclear factor-κB (NF-κB), Toll-like-receptor-2 (TLR2) and Toll-like-receptor-4 (TLR4). In this study, we established an HFD-induced cardiac injury mouse model and palmitate (PA)-induced myocardial cell model to evaluate the role of TLR2 in OIC. Our data show that TLR2 blockade using TLR2 knockout (KO) mice or a TLR2-specific inhibitor, C29, markedly ameliorated HFD- or PA-induced inflammation, myocardial fibrosis, and hypertrophy both in vivo and in vitro. Moreover, the PA-induced myocardial cell injury was mediated via inducing the formation of TLR2-MyD88 complex in a TLR4-independent manner in cardiomyocytes. Our data prove the critical role of cardiac TLR2 in the pathogenesis of HFD- and saturated fatty acid-induced myocarditis, fibrosis, myocardial hypertrophy, and cardiac dysfunction. Inhibition of TLR2 pathway may be a therapeutic strategy of OIC.

Toll-like receptor 2 deficiency relieves splenic immunosuppression during sepsis

Immunosuppression is associated with long-term mortality during sepsis. However, the underlying mechanism of immunosuppression remains poorly understood. Toll-like receptor 2 (TLR2) contributes to sepsis pathogenesis. We sought to determine the role of TLR2 in immunosuppression in the spleen during polymicrobial sepsis. Using an experimental model of polymicrobial sepsis induced by cecal ligation and puncture (CLP), we measured the expression of inflammatory cytokines and chemokines in spleen 6 and 24 h after CLP to evaluate the immune response, and compared the expression of inflammatory cytokines and chemokines, apoptosis, and intracellular ATP production in spleen of wild-type (WT) and TLR2-deficient (TLR2^-/-) mice 24 h after CLP. We found that pro-inflammatory cytokines and chemokines, such as TNF-α and IL-1β peaked 6 h after CLP, while IL-10, an anti-inflammatory cytokine, peaked 24 h after CLP in the spleen. At this later time point, TLR2^-/- mice presented decreased levels of IL-10 and decreased caspase 3 activation but no significant difference in intracellular ATP production in spleen compared to WT mice. Our data imply that TLR2 has a pronounced effect on sepsis-induced immunosuppression in spleen.

mtROS Induced via TLR-2-SOCE Signaling Plays Proapoptotic and Bactericidal Role in Mycobacterium fortuitum-Infected Head Kidney Macrophages of Clarias gariepinus

The mechanisms underlying Mycobacterium fortuitum-induced mycobacteriosis remain unexplored. Using head kidney macrophages (HKM) from catfish (Clarias gariepinus), we report that Ca²⁺ surge across mitochondrial-Ca²⁺ uniporter (MICU), and consequent mitochondrial ROS (mtROS) production, is imperative for mycobactericidal activity. Inhibition of mtROS alleviated HKM apoptosis and enhanced bacterial survival. Based on RNA interference (RNAi) and inhibitor studies, we demonstrate that the Toll-like receptor (TLR)-2–endoplasmic reticulum (ER) stress–store-operated calcium entry (SOCE) axis is instrumental for activating the mt-Ca²⁺/mtROS cascade in M. fortuitum-infected HKM. Additionally, pharmacological inhibition of mtROS attenuated the expression of CHOP, STIM1, and Orai1, which suggests a positive feedback loop between ER-stress-induced SOCE and mtROS production. Elevated tumor necrosis factor alpha (TNF-α) levels and caspase-8 activity were observed in HKM consequent to M. fortuitum infection, and our results implicate that mtROS is crucial in activating the TNF-mediated caspase-8 activation. Our results for the first time demonstrate mitochondria as an innate immune signaling center regulating mycobacteriosis in fish. We conclude that M. fortuitum-induced persistent SOCE signaling leads to mtROS production, which in turn activates the TNF-α/caspase-8 axis culminating in HKM apoptosis and bacterial clearance.

Targeting Toll-Like Receptors in Sepsis: From Bench to Clinical Trials

Significance: Sepsis is a critical clinical syndrome with life-threatening organ dysfunction induced by a dysregulated host response to infection. Despite decades of intensive research, sepsis remains a leading cause of in-hospital mortality with few specific treatments. Recent Advances: Toll-like receptors (TLRs) are a part of the innate immune system and play an important role in host defense against invading pathogens such as bacteria, virus, and fungi. Using a combination of genetically modified animal models and pharmacological agents, numerous preclinical studies during the past two decades have demonstrated that dysregulated TLR signaling may contribute to sepsis pathogenesis. However, many clinical trials targeting inflammation and innate immunity such as TLR4 have yielded mixed results. Critical Issues: Here we review various TLRs and the specific molecules these TLRs sense-both the pathogen-associated and host-derived stress molecules, and their converging signaling pathways. We critically analyze preclinical investigations into the role of TLRs in animal sepsis, the complexity of targeting TLRs for sepsis intervention, and the disappointing clinical trials of the TLR4 antagonist eritoran. Future Directions: Future sepsis treatments will depend on better understanding the complex biological mechanisms of sepsis pathogenesis, the high heterogeneity of septic humans as defined by clinical presentations and unique immunological biomarkers, and improved stratifications for targeted interventions.

Dysregulated Immunity and Immunotherapy after Sepsis

Implementation of protocolized surveillance, diagnosis, and management of septic patients, and of surgical sepsis patients in particular, is shown to result in significantly increased numbers of patients surviving their initial hospitalization. Currently, most surgical sepsis patients will rapidly recover from sepsis; however, many patients will not rapidly recover, but instead will go on to develop chronic critical illness (CCI) and experience dismal long-term outcomes. The elderly and comorbid patient is highly susceptible to death or CCI after sepsis. Here, we review aspects of the Persistent Inflammation, Immunosuppression, and Catabolism Syndrome (PICS) endotype to explain the underlying pathobiology of a dysregulated immune system in sepsis survivors who develop CCI; then, we explore targets for immunomodulatory therapy.

Immunological Endotyping of Chronic Critical Illness After Severe Sepsis

Improved management of severe sepsis has been one of the major health care accomplishments of the last two decades. Due to enhanced recognition and improved management of severe sepsis, in-hospital mortality has been reduced by up to 40%. With that good news, a new syndrome has unfortunately replaced in-hospital multi-organ failure and death. This syndrome of chronic critical illness (CCI) includes sepsis patients who survive the early "cytokine or genomic storm," but fail to fully recover, and progress into a persistent state of manageable organ injury requiring prolonged intensive care. These patients are commonly discharged to long-term care facilities where sepsis recidivism is high. As many as 33% of sepsis survivors develop CCI. CCI is the result, at least in part, of a maladaptive host response to chronic pattern-recognition receptor (PRR)-mediated processes. This maladaptive response results in dysregulated myelopoiesis, chronic inflammation, T-cell atrophy, T-cell exhaustion, and the expansion of suppressor cell functions. We have defined this panoply of host responses as a persistent inflammatory, immune suppressive and protein catabolic syndrome (PICS). Why is this important? We propose that PICS in survivors of critical illness is its own common, unique immunological endotype driven by the constant release of organ injury-associated, endogenous alarmins, and microbial products from secondary infections. While this syndrome can develop as a result of a diverse set of pathologies, it represents a shared outcome with a unique underlying pathobiological mechanism. Despite being a common outcome, there are no therapeutic interventions other than supportive therapies for this common disorder. Only through an improved understanding of the immunological endotype of PICS can rational therapeutic interventions be designed.

Hydrogen Gas Alleviates Sepsis-Induced Brain Injury by Improving Mitochondrial Biogenesis Through the Activation of PGC-α in Mice

ABSTRACT

Sepsis-associated encephalopathy (SAE) affects approximately one-third of septic patients, and there is a lack of effective therapeutics for SAE. Hydrogen gas is a new medical gas that exerts anti-inflammation, antioxidation, and anti-apoptotic effects and can effectively protect septic mice. Mitochondrial dysfunction, which can be improved by mitochondrial biogenesis, is a type of molecular pathology in sepsis. Peroxisome proliferator-activated receptor gamma co-activator 1α (PGC-1α), which can be inhibited by SR-18292, is the key regulatory factor of mitochondrial biogenesis. Therefore, we investigated the effects of hydrogen gas on mitochondrial function and mitochondrial biogenesis in mice with SAE and the related regulatory mechanisms. Cecal ligation and puncture was used to induce sepsis in mice. The mice with hydrogen gas therapy were exposed to 2% H2 inhalation for 1 h beginning at both 1 and 6 h after operation, and mice were also injected with a PGC-1α inhibitor, SR-18292. We recorded the 7-day survival rates of the mice and detected their cognitive function using a Y-maze test. The Nissl bodies in the CA1 region of hippocampus were observed by Nissl staining, and the apoptotic cells were observed by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling assay staining. The mitochondrial membrane potential (MMP), adenosine triphosphate (ATP) level, and mitochondrial respiratory chain complexes I and II were analyzed using commercial kits. The mitochondrial morphology was observed by transmission electron microscopy. The expression levels of PGC-1α, nuclear respiratory factor 2 (NRF2), and mitochondrial transcription factor A (Tfam) were detected by Western blot analysis. The present study showed that hydrogen gas therapy increased the 7-day survival rate, improved cognitive function, increased the mitochondrial function (MMP, ATP level, complex I activity) and expression of mitochondrial biogenesis parameters (PGC-1α, NRF2, Tfam). However, the injection of SR-18292 (a PGC-1α inhibitor) decreased mitochondrial function, PGC-1α activation, and expression of NRF2 and Tfam. Therefore, these results indicate that hydrogen gas alleviates sepsis-induced brain injury in mice by improving mitochondrial biogenesis through the activation of PGC-1α.

18β-glycyrrhetinic acid inhibited mitochondrial energy metabolism and gastric carcinogenesis through methylation-regulated TLR2 signaling pathway

The natural phenolic substance, 18β-glycyrrhetinic acid (GRA), has shown enormous potential in the chemoprevention of cancers with rich resources and biological safety, but the GRA-regulated genetic and epigenetic profiles are unclear. Deregulated mitochondrial cellular energetics supporting higher adenosine triphosphate provisions relative to the uncontrolled proliferation of cancer cells is a cancer hallmark. The Toll-like receptor 2 (TLR2) signaling pathway has emerged as a key molecular component in gastric cancer (GC) cell proliferation and epithelial homeostasis. However, whether TLR2 influenced GC cell energy metabolism and whether the inhibition effects of GRA on GC relied on TLR2 signaling were not illustrated. In the present study, TLR2 mRNA and protein expression levels were elevated in gastric tumors in the K19-Wnt1/C2mE (Gan) mice model, GC cell lines and human GCs, and the overexpression of TLR2 was correlated with the high histological grade and was a poor prognostic factor in GC patients. Further gain and loss of function showed that TLR2 activation induced GC cell proliferation and promoted reactive oxygen species (ROS) generation, Ca2+ accumulation, oxidative phosphorylation and the electron transport chain, while blocking TLR2 inhibited mitochondrial function and energy metabolism. Furthermore, GRA pretreatment inhibited TLR2-activated GC cell proliferation, energy metabolism and carcinogenesis. In addition, expression of TLR2 was found to be downregulated by GRA through methylation regulation. Collectively, the results demonstrated that GRA inhibited gastric tumorigenesis through TLR2-accelerated energy metabolism, suggesting GRA as a promising therapeutic agency targeting TLR2 signaling in GC.

Triaryl Pyrazole Toll-Like Receptor Signaling Inhibitors: Structure-Activity Relationships Governing Pan- and Selective Signaling Inhibitors

The immune system uses members of the toll-like receptor (TLR) family to recognize a variety of pathogen- and host-derived molecules in order to initiate immune responses. Although TLR-mediated, pro-inflammatory immune responses are essential for host defense, prolonged and exaggerated activation can result in inflammation pathology that manifests in a variety of diseases. Therefore, small-molecule inhibitors of the TLR signaling pathway might have promise as anti-inflammatory drugs. We previously identified a class of triaryl pyrazole compounds that inhibit TLR signaling by modulation of the protein-protein interactions essential to the pathway. We have now systematically examined the structural features essential for inhibition of this pathway, revealing characteristics of compounds that inhibited all TLRs tested (pan-TLR signaling inhibitors) as well as compounds that selectively inhibited certain TLRs. These findings reveal interesting classes of compounds that could be optimized for particular inflammatory diseases governed by different TLRs.

Use of plasma mitochondrial DNA levels for determining disease severity and prognosis in pediatric sepsis: a case control study

BACKGROUND

The mortality rate due to severe sepsis is approximately 30-60%. Sepsis readily progresses to septic shock and multiple organ dysfunction, representing a significant problem in the pediatric intensive care unit (PICU). The aim of this study was to explore the value of plasma mitochondrial DNA (mtDNA) for early diagnosis and prognosis in children with sepsis.

METHODS

A total of 123 children with sepsis who were hospitalized in the Hunan Children's Hospital PICU from July 2013 to December 2014 were divided into the general sepsis group (n = 70) and severe sepsis group (n = 53) based on diagnostic standards. An additional 30 children with non-sepsis infection and 30 healthy children were randomly selected as a control group. Patients' plasma was collected during admission to the PICU. A pediatric critical illness score (PCIS) was also calculated. The plasma mtDNA level was examined using real-time polymerase chain reaction technology, and other parameters including routine laboratory values; blood lactate, procalcitonin (PCT), and C-reactive protein (CRP) levels; and data on survival were collected and compared among the groups.

RESULTS

The plasma mtDNA level in the sepsis group than that in the non-sepsis infection and healthy groups. The plasma mtDNA level was significantly higher in the severe sepsis than in the general sepsis group (p < 0.001). A lower PCIS was associated with a higher plasma mtDNA level (p < 0.001). A higher number of organs with dysfunction was associated with higher plasma mtDNA levels (p < 0.001). Plasma mtDNA levels were higher among patients with elevated alanine aminotransferase, aspartate aminotransferase, blood urea nitrogen, creatinine, lactate dehydrogenase, creatine kinase, myoglobin, creatine kinase MB, and troponin than in those with values within the normal range. The mtDNA level was higher among non-survivors than among survivors, and this difference was significant. mtDNA showed a prognostic prediction value similar to that of lactate, PCT, and CRP.

CONCLUSIONS

Plasma mtDNA levels may be a suitable biomarker for diagnosis and prognosis in children with sepsis.

Chronic Critical Illness and the Persistent Inflammation, Immunosuppression, and Catabolism Syndrome

Dysregulated host immune responses to infection often occur, leading to sepsis, multiple organ failure, and death. Some patients rapidly recover from sepsis, but many develop chronic critical illness (CCI), a debilitating condition that impacts functional outcomes and long-term survival. The “Persistent Inflammation, Immunosuppression, and Catabolism Syndrome” (PICS) has been postulated as the underlying pathophysiology of CCI. We propose that PICS is initiated by an early genomic and cytokine storm in response to microbial invasion during the early phase of sepsis. However, once source control, antimicrobial coverage, and supportive therapies have been initiated, we propose that the persistent inflammation in patients developing CCI is a result of ongoing endogenous alarmin release from damaged organs and loss of muscle mass. This ongoing alarmin and danger-associated molecular pattern signaling causes chronic inflammation and a shift in bone marrow stem cell production toward myeloid cells, contributing to chronic anemia and lymphopenia. We propose that therapeutic interventions must target the chronic organ injury and lean tissue wasting that contribute to the release of endogenous alarmins and the expansion and deposition of myeloid progenitors that are responsible for the propagation and persistence of CCI.

Protective effects of exogenous NaHS against sepsis-induced myocardial mitochondrial injury by enhancing the PGC-1α/NRF2 pathway and mitochondrial biosynthesis in mice

This study aimed to examine whether exogenous NaHS can protect myocardial mitochondrial injury from sepsis by enhancing the peroxisome proliferator-activated receptor gamma co-activator 1α (PGC-1α)/ nuclear factor erythroid-2-related factor 2 (NRF2) pathway and mitochondrial biosynthesis in mice. Animals were divided into sham-operated, sepsis, sepsis + 25 μmol/L NaHS, sepsis + 50 μmol/L NaHS, sepsis + 100 μmol/L NaHS, and sepsis + 200 μmol/L NaHS groups. The myocardial damage was evaluated by hematoxylin and eosin staining for myocardial microstructure and serum cardiac troponin I (cTnI) detection. The myocardial mitochondrial damage was evaluated through transmission electron microscopic observation of mitochondrial microstructure and detection of the degree of myocardial mitochondrial swelling. The adenosine triphosphate (ATP) level was used to appraise the mitochondrial function. The mRNA expression levels of Nrf2, PGC-1α, and Tfam were analyzed to explore the molecular mechanism.

RESULTS

In the sepsis group, the structure of myocardial tissue and mitochondria were significantly damaged, the serum cTnI level increased (P < 0.05), the ATP level reduced, the degree of myocardial mitochondrial swelling aggravated, and the mRNA expression levels of Nrf2, PGC-1α, and Tfam increased (P < 0.05). After NaHS treatment, the structure of myocardial tissue and mitochondria improved, the cTnI level reduced, the ATP level increased, the degree of myocardial mitochondrial swelling alleviated, and the mRNA expression level of Nrf2, PGC-1α, and Tfam increased continuously in a dose-dependent manner (P < 0.05).

CONCLUSIONS

Exogenous NaHS had a protective effect against myocardial mitochondrial injury in sepsis. The mechanism might lie in enhancing the PGC-1α/NRF2 pathway and mitochondrial biosynthesis.

Circadian Rhythms Influence the Severity of Sepsis in Mice via a TLR2-Dependent, Leukocyte-Intrinsic Mechanism

Circadian rhythms coordinate an organism's activities and biological processes to the optimal time in the 24-h daylight cycle. We previously demonstrated that male C57BL/6 mice develop sepsis more rapidly when the disease is induced in the nighttime versus the daytime. In this report, we elucidate the mechanism of this diurnal difference. Sepsis was induced via cecal ligation and puncture (CLP) at zeitgeber time (ZT)-19 (2 am) or ZT-7 (2 pm). Like the males used in our prior study, female C57BL/6 mice had a worse outcome when CLP was induced at ZT-19 versus ZT-7, and these effects persisted when we pooled the data from both sexes. In contrast, mice with a mutated Period 2 (Per2) gene had a similar outcome when CLP was induced at ZT-19 versus ZT-7. Bone marrow chimeras reconstituted with C57BL/6 immune cells exhibited a worse outcome when sepsis was induced at ZT-19 versus ZT-7, whereas chimeras with Per2-mutated immune cells did not. Next, murine macrophages were subjected to serum shock to synchronize circadian rhythms and exposed to bacteria cultured from the mouse cecum at 4-h intervals for 48 h. We observed that IL-6 production oscillated with a 24-h period in C57BL/6 cells exposed to cecal bacteria. Interestingly, we observed a similar pattern when cells were exposed to the TLR2 agonist lipoteichoic acid. Furthermore, TLR2-knockout mice exhibited a similar sepsis phenotype when CLP was induced at ZT-19 versus ZT-7. Together, these data suggest that circadian rhythms in immune cells mediate diurnal variations in murine sepsis severity via a TLR2-dependent mechanism.

Apoptin Gene Delivery by the Functionalized Polyamidoamine (PAMAM) Dendrimer Modified with Ornithine Induces Cell Death of HepG2 Cells

The use of tumor-specific therapeutic agents is a promising option for efficient and safe nonviral gene transfer in gene therapy. In this study, we describe the efficacy of polyamidoamine (PAMAM)-based nonviral gene delivery carriers, namely, an ornithine conjugated PAMAM (PAMAM-O) dendrimer in delivering apoptin, a tumor-specific killer gene, into human hepatocellular carcinoma (HepG2 cells) and dermal fibroblasts. We analyzed the transfection efficiency by the luciferase assay and assessed cell viability in both cell types. The transfection efficiency of the PAMAM-O dendrimer was found to be higher than that of the PAMAM dendrimer. Moreover, the cytotoxicity of the PAMAM-O dendrimer was very low. We treated both cell types with a polyplex of PAMAM-O dendrimer with apoptin, and analyzed its cellular uptake and localization by confocal microscopy. Cell cycle distribution, tetramethylrhodamine, ethyl ester (TMRE) analysis, and transmission electron microscopy imaging showed that apoptin induced cell death in HepG2 cells. We therefore demonstrated that a PAMAM-O/apoptin polyplex can be used as an effective therapeutic strategy in cancer owing to its effectiveness as a suitable nonviral gene vector for gene therapy.

The role of myeloid differentiation factor 88 on mitochondrial dysfunction of peritoneal leukocytes during polymicrobial sepsis

OBJECTIVE

To investigate the role of myeloid differentiation factor 88 (MyD88) on mitochondrial dysfunction of peritoneal leukocytes during polymicrobial sepsis.

MATERIAL AND METHODS

Polymicrobial peritonitis, a clinically relevant mouse model of sepsis, was generated by cecum ligation and puncture (CLP) in both male C57BL/6J wild-type (WT) and MyD88 knockout (MyD88(-/-)) mice. Twenty-four hours after surgeries, peritoneal leukocytes were collected and four parameters of mitochondrial function, including total intracellular and mitochondrial ROS burst, mitochondrial membrane depolarization and ATP depletion, were measured by flow cytometry or ATP assay, and then compared.

RESULTS

Polymicrobial sepsis led to a marked mitochondrial dysfunction of peritoneal leukocytes with total intracellular and mitochondrial ROS overproduction, decreased mitochondrial membrane potential and reduced intracellular ATP production. In comparison, there was no significant difference in the extent of mitochondrial dysfunction of peritoneal leukocytes between WT and MyD88(-/-) septic mice.

CONCLUSIONS

MyD88 may be not sufficient to regulate mitochondrial dysfunction of peritoneal leukocytes during polymicrobial sepsis.

MFHAS1 Is Associated with Sepsis and Stimulates TLR2/NF-κB Signaling Pathway Following Negative Regulation

Malignant fibrous histiocytoma amplified sequence 1 (MFHAS1) has a potential immunoregulatory role dependent on Toll-like receptors (TLRs). TLR2, associated with deleterious systemic inflammation, cardiac dysfunction, and acute kidney injury, acts synergistically in sepsis. The role of MFHAS1 in targeting TLR2 involved in sepsis has not been examined thus far. This study aimed to examine the relationship of MFHAS1 and sepsis, and the effect of MFHAS1 on the TLR2 signaling pathway. Blood samples were collected from eight sepsis patients after surgery and eight patients undergoing selective surgery to determine blood MFHAS1 levels. HEK 293 cells, RAW 264.7 macrophages and THP-1 monocytes were used to confirm the effect of MFHAS1 on TLR2 signaling pathway. Our study showed that blood MFHAS1 was significantly elevated in septic patients, and MFHAS1 was more increased in mononuclear cells from septic patients. Pam3CSK4 (TLR2 ligand) was found to induce MFHAS1 production in RAW 264.7 murine macrophages and THP-1 human monocytes in a time-dependent manner. MFHAS1 has dual effects on TLR2 signaling pathway and inflammation, i.e., inhibitory effect at 6 hours, and then stimulatory effect after 24 hours through the activation of TLR2/NF-κB signaling pathway, and MFHAS1 induced the phosphorylation of JNK and p38 after TLR2 stimulation.

Poly (ADP-ribose) synthetase inhibitor has a heart protective effect in a rat model of experimental sepsis

The aim of this study is to investigate whether PARP inhibitor could reduce cell apoptosis and injury in the heart during sepsis.

MATERIALS AND METHODS

60 healthy male Sprague-Dawley (SD) rats were randomly divided into 4 groups---sham group, modal group, 3-AB pretreatment group and 3-AB treatment group, 15 rats per group. The cecal ligation and puncture (CLP) model of sepsis was used. The following were determined--levels of malondialdehyde (MDA), ATP and nicotinamide adenine dinucleotide (NAD+), expression of PARP, Bcl-2, Bax, cytochrome C and caspase 3 activity in the myocardium tissue, levels of serum creatine kinase muscle brain (CK-MB) fraction and troponin I.

RESULTS

Histological and molecular analyses showed that myocardial cells apoptosis were associated with mitochondria injury, with an increase in the amount of PARP and a decrease in ATP and NAD+ levels in model group. In addition, the levels of Bax, cytochrome C and caspase 3 activity, serum levels of CK-MB and troponin I increased, but levels of Bcl-2 significantly decreased. Inhibition of PARP upregulated the levels of ATP, NAD + and Bcl-2, and significantly reduced the activation of PARP and caspase 3, decreased the levels of MDA, cytochrome C, CK-MB and troponin I. As a result, apoptosis in the heart was attenuated.

CONCLUSION

These results indicate that PARP activation may be involved in apoptosis in the heart induced by sepsis and 3-AB could improve it.