Silencing Cardiac Troponin I-Interacting Kinase Reduces Lipopolysaccharide-Induced Sepsis-Induced Myocardial Dysfunction in Rat by Regulating Apoptosis-Related Proteins

Golgi Protein 73 Promotes LPS-Induced Cardiac Dysfunction via Mediating Myocardial Apoptosis and Autophagy

ABSTRACT

Sepsis-induced cardiac dysfunction represents a major cause of high mortality in intensive care units with limited therapeutic options. Golgi protein 73 (GP73) has been implicated in various diseases. However, the role of GP73 in lipopolysaccharide (LPS)-induced cardiac dysfunction is unclear. In this study, we established a sepsis-induced cardiac dysfunction model by LPS administration in wild-type and GP73 knockout ( GP73-/- ) mice. We found that GP73 was increased in LPS-treated mouse hearts and LPS-cultured neonatal rat cardiomyocytes (NRCMs). Knockout of GP73 alleviated myocardial injury and improved cardiac dysfunction. Moreover, depletion of GP73 in NRCMs relieved LPS-induced cardiomyocyte apoptosis and activated myocardial autophagy. Therefore, GP73 is a negative regulator in LPS-induced cardiac dysfunction by promoting cardiomyocyte apoptosis and inhibiting cardiomyocyte autophagy.

NLRP3 inflammasome involves in the pathophysiology of sepsis-induced myocardial dysfunction by multiple mechanisms

Sepsis-induced myocardial dysfunction (SIMD) is one of the serious health-affecting problems worldwide. At present, the mechanisms of SIMD are still not clearly elucidated. The NOD-like receptor protein 3 (NLRP3) inflammasome has been assumed to be involved in the pathophysiology of SIMD by regulating multiple biological processes. NLRP3 inflammasome and its related signaling pathways might affect the regulation of inflammation, autophagy, apoptosis, and pyroptosis in SIMD. A few molecular specific inhibitors of NLRP3 inflammasome (e.g., Melatonin, Ulinastatin, Irisin, Nifuroxazide, and Ginsenoside Rg1, etc.) have been developed, which showed a promising anti-inflammatory effect in a cellular or animal model of SIMD. These experimental findings indicated that NLRP3 inflammasome could be a promising therapeutic target for SIMD treatment. However, the clinical translation of NLRP3 inhibitors for treating SIMD still requires robust in vivo and preclinical trials.

USP13 reduces septic mediated cardiomyocyte oxidative stress and inflammation by inducing Nrf2

BACKGROUND

Sepsis is a common cardiovascular complication that can cause heart damage. The regulatory role of ubiquitin-specific peptidase 13 (USP13) on erythroid 2-related factor 2 (Nrf2) has been reported, but its regulatory role in septic cardiomyopathy remains unclear.

METHODS

The Sprague Dawley (SD) rat model of septic myocardial injury was constructed by lipopolysaccharides (LPS). The serum lactate dehydrogenase (LDH) and creatine kinase (CK) levels were detected, the mRNA and protein expression levels of Nrf2 and USP13 in tissues were detected by real-time quantitative reverse transcription PCR (qRT-PCR) and western blot (WB), and the expression of USP13 at the treatment time of 3 h, 6 h, and 12 h was also detected. The cell viability and USP13, Nrf-2 and heme oxygenase-1 (HO-1) expression levels of H9C2-treated cells by LPS and the oxidative stress level and inflammatory response of H9C2 cells were detected by enzyme-linked immunosorbent assay (ELISA) and WB.

RESULTS

The results showed that USP13 was downregulated in septic myocardial injury tissues, and the Nrf2 level was increased in vitro after the cells were treated with LPS. Overexpression of USP13 further induced Nrf2 to reduce apoptosis, oxidative stress, and expression of inflammatory factors.

CONCLUSION

In conclusion, this study demonstrated that USP13 was downregulated in septic myocardial injury tissues, and USP13 overexpression increased Nrf2 levels and reduced apoptosis. Further studies showed that USP13 reduced LPS-induced oxidative stress and inflammation by inducing Nrf2.

DAMPs Released from Proinflammatory Macrophages Induce Inflammation in Cardiomyocytes via Activation of TLR4 and TNFR

Cardiac dysfunction is a life-threatening complication in sepsis. Upon infection and cardiac stress, the cardiac macrophage population expands. Recruited macrophages exhibit a predominantly proinflammatory phenotype and release danger-associated molecular patterns (DAMPs) that contribute to cardiac dysfunction. However, the underlying pathomechanisms are highly complex and not fully understood. Here, we utilized an indirect macrophage-cardiomyocyte co-culture model to study the effects of proinflammatory macrophages on the activation of different cardiac receptors (TLR3, TLR4, and TNFR) and their role in cardiac inflammation and caspase-3/7 activation. The stimulation of cardiomyocytes with conditioned medium of LPS-stimulated macrophages resulted in elevated IL-6 protein concentrations and relative IL-6 and TNFα mRNA levels. Conditioned medium from LPS-stimulated macrophages also induced NFκB translocation and increased caspase-3/7 activation in cardiomyocytes. Analyzing the role of different cardiac receptors, we found that TLR4 and TNFR inhibition reduces cardiac inflammation and that the inhibition of TNFR prevents NFκB translocation into the nuclei of cardiomyocytes, induced by exposure to conditioned medium of proinflammatory macrophages. Moreover, we demonstrated that TLR3 inhibition reduces macrophage-mediated caspase-3/7 activation. Our results suggest that the immune response of macrophages under inflammatory conditions leads to the release of DAMPs, such as eRNA and cytokines, which in turn induce cardiomyocyte dysfunction. Thus, the data obtained in this study contribute to a better understanding of the pathophysiological mechanisms of cardiac dysfunction.

Evaluation Value and Clinical Significance of Cardiac Troponin Level and Pediatric Sequential Organ Failure Score in the Definition of Sepsis 3.0 in Critically Ill Children

Objective

A case-control study was conducted to explore the value and clinical significance of troponin level and pediatric sequential organ failure score in the evaluation of sepsis 3.0 definition in critically ill children.

Methods

180 children with sepsis who were admitted to the ICU from March 2019 to June 2021 were enrolled in our hospital as the research objects. In addition, 100 children with general infection did not meet the diagnostic criteria of systemic inflammatory response syndrome (SIRS) as controls. The creatine kinase MB (CK-MB) and cardiac troponin I (cTnI) data at the 1st and 24-72 h after admission to pediatric intensive care unit (PICU) were enrolled as the observation indexes of myocardial enzymology. In the meantime, the relevant literature was reviewed to obtain the indicators related to sepsis death. The data of the first examination in the medical history data were enrolled for analysis. According to the definition of sepsis 3.0 in critically ill children, they were assigned into sepsis and nonsepsis group. According to the survival outcome of discharge and 30 days after discharge, the patients were assigned into the death subgroup and survival subgroup and were assigned into the sequential organ failure assessment (SOFA) score ≥ 2 subgroup and< 2 subgroup according to SOFA score. COX proportional hazard regression was used to analyze the relationship between CK-MB, cTnI, and SOFA scores and prognosis. ROC curve was adopted to analyze the value of CK-MB, cTnI, and SOFA scores in the evaluation of critical sepsis in children.

Results

Univariate analysis indicated that the prognosis of children with sepsis was correlated with abnormal levels of CK-MB and cTnI, SOFA score, oxygenation index < 200, mean arterial pressure, and Glasgow coma scale (GCS), and the difference was statistically significant (P < 0.05). The results of COX regression analysis indicated that the variables that were remarkably associated with death from sepsis in children were CK-MB, elevated cTnI levels, and SOFA score ≥ 2, and serum cTnI and/or CK-MB levels and SOFA score were remarkably higher correlation (r = 0.453, P < 0.05). In terms of the myocardial enzyme levels in the sepsis group and the nonsepsis group, the levels of CK-MB and (or) cTnI augmented in 121/180 cases (67.22%) in the sepsis group and in 19/100 cases (19.00%) in the nonsepsis group. The levels of CK-MB and (or) cTnI were augmented, and the difference was statistically significant (P < 0.05). The levels of CK-MB and cTnI in the sepsis group at admission to ICU and 24 to 72 hours after admission were remarkably higher compared to the nonsepsis group. The levels of CK-MB and cTnI at 24-72 h were higher compared to ICU. The myocardial enzyme levels of different SOFA scores and survival outcome subgroups in the sepsis group were compared. The subgroup with SFOA score ≥ 2 points had remarkably higher levels of CK-MB and (or) cTnI than the subgroup with <2 points. The survival subgroup of CK-MB and cTnI level was remarkably higher compared to the death subgroup, the CK-MB and cTnI levels in each subgroup at 224-72 hours were remarkably higher compared to the ICU, and the difference was statistically significant (P < 0.05). Kaplan-Meier method and log-rank test indicated that the survival rates of groups 1 to 4 at 30 days were 33.23%, 78.71%, 40.03%, and 100.00%, respectively. The average survival time and their 95% CI were 12.82 d (10.52~ 16.26 d), 22.34 d (18.76~ 25.81 d), 14.65 d (11.62~ 16.38 d), and 30 d (30.00~ 30.00 d), respectively. Pairwise comparison indicated that the survival time of children in group 1 was the shortest, and that in group 4 was the longest. The results of ROC curve research showed that the CK-MB, cTnI, and SOFA scores and AUC for the combination test were 0.778 (95% CI 0.642–0.914), 0.736 (95% CI 0.602–0.890), 0.848 (95% CI 0.733–0.963), and 0.934 (95% CI 0.854–0.999), respectively. The AUC of combined diagnosis was remarkably higher compared to single factor prediction, and the difference was statistically significant (P < 0.05). Predictive value showed the joint test > SOFA score > CK − MB > cTnI.

Conclusion

Troponin level and pediatric SOFA score can be adopted as effective indicators to assess the severity and prognosis of patients with sepsis and can guide the formulation of a reasonable treatment plan.

Knockout of Cardiac Troponin I-Interacting Kinase leads to cardiac dysfunction and remodeling

Cardiac troponin I-interacting kinase (TNNI3K) is a cardiac-specific kinase that has been identified as a diagnostic marker and a therapeutic target in cardiovascular diseases. However, the biological function of TNNI3K in cardiac dysfunction and remodeling remain elusive. In the present study, a Tnni3k cardiomyocyte-specific knockout (Tnni3k-cKO) mouse model was established. Echocardiography was used to evaluate cardiac function in mice. Heart failure markers were detected using enzyme-linked immunosorbent assay. Hematoxylin and eosin staining, wheat germ agglutinin staining, Masson's trichrome staining, Sirius red staining, and TUNEL staining were used to assess histopathological changes, cardiac hypertrophy, collagen deposition, and myocardial apoptosis, respectively. Expression levels of TNNI3K, apoptosis-related proteins, and p38 mitogen-activated protein kinase were measured using Western blot analysis. Compared to wild-type controls, cardiac dysfunction and cardiac remodeling of Tnni3k-cKO mice increased gradually with age. Tnni3k-cKO mice exhibited cardiac hypertrophy, cardiac fibrosis, and cardiomyocyte apoptosis. Upregulation of cleaved caspase-3 in Tnni3k-cKO mice appeared to be related to phosphorylation and activation of the p38 mitogen-activated protein kinase signaling pathway. In conclusion, this study shows that TNNI3K is essential for cardiac development and function, providing new insights into the development of novel therapeutic strategies for cardiac diseases.

Electroacupuncture at Zusanli Alleviates Sepsis by Regulating the TLR4-MyD88-NF-Kappa B Pathway and Diversity of Intestinal Flora

Background

Electroacupuncture (EA) at the Zusanli acupoint (ST36) has shown therapeutic potential for sepsis due to its ability to limit inflammation and to regulate gastrointestinal tract symptoms. However, the mechanisms contributing to the effects of EA at ST36 on sepsis and connections with the intestinal flora remain unclear. This study was designed to explore the effects of EA at ST36 on Toll-like receptor 4 signaling and the intestinal flora.

Methods

ICR mice were randomly divided into 4 groups: control group, model group, EA group, and sham EA group. EA at ST36 was performed at 2.5 mA and 2 to 100 Hz, and the 30 min of dense wave was achieved over 5 days. A sepsis model was built by intraperitoneal injection of lipopolysaccharide (LPS, 10 mg/mL). The levels of expression of interleukin-1β (IL-1β), IL-6, tumor necrosis factor-α (TNF-α), and IL-10 were detected by enzyme-linked immunosorbent assays, and lactate dehydrogenase (LDH) levels in serum were measured by biochemical tests. Expression levels of Bax, Bcl2, cleaved caspase-3, Toll-like receptor (TLR4), nuclear factor-kappa B (NF-κB), and myeloid differentiation factor 88 (MyD88) were assessed by the Western blotting. Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) staining was used to evaluate apoptosis. The intestinal microecology was assessed via 16S rRNA gene sequencing.

Results

EA at ST36 reduced the expression of IL-1β, IL-6, and TNF-α and increased the expression of IL-10 to inhibit the inflammatory response. EA at ST36 also inhibited apoptosis, as measured by TUNEL staining, and decreased the Bax/Bcl2 ratio and levels of caspase-3 and cleaved caspase-3, as well as LDH release. Our results suggest that alleviation of sepsis may correlate with the downregulation of levels of TLR4, NF-κB, and MyD88. Importantly, EA at ST36 improved the diversity of the intestinal flora and increased the abundance of Firmicutes and Actinobacteria. Conclusion. EA at ST36 prevented sepsis from worsening by inhibiting inflammation and apoptosis, which correlated with the regulation of the TLR4/NF-κB/MyD88 signaling axis and modulation of the intestinal flora.

Protective Effects of Dexmedetomidine on Sepsis-Induced Vascular Leakage by Alleviating Ferroptosis via Regulating Metabolic Reprogramming

Introduction

Vascular leakage plays a vital role in sepsis-induced multi-organ dysfunction. Currently, no specific measures are available for vascular leakage. Ferroptosis, as a recently recognized form of cell death, plays a crucial role in cell dysfunction. It is still unknown whether ferroptosis participates in the occurrence of organ dysfunction following sepsis. Our previous study showed that dexmedetomidine (Dex) could alleviate sepsis-induced organ dysfunction. However, whether the mechanism is related to ferroptosis is not clear.

Methods

The publicly available datasets of septic patients were reanalyzed, and septic models in vivo and vitro by cecal ligation and puncture and lipopolysaccharide-stimulated vascular endothelial cells (VECs) were applied. The occurrence of ferroptosis in septic patients and rats was observed, and the protective effects of Dex on ferroptosis, and related mechanisms on regulating metabolic reprogramming and mitochondrial fission were further studied.

Results

The transcriptomics data of patients from the GEO database showed that ferroptosis was closely related to sepsis. Sepsis induced significant ferroptosis in VECs by metabolomics analysis. The level of lipid peroxidation was increased in VECs, and the mitochondrial cristae was decreased after sepsis. Metabolomics analysis showed that Dex activated the pentose phosphate pathway and increased glutathione in VECs via up-regulation of G6PD expression. Dex could antagonize sepsis-induced the decrease in the level of Nrf2. The Nrf2 inhibitor reversed the protective effect of Dex on ferroptosis. Further study showed that Dex significantly alleviated sepsis-induced mitochondrial over-division, improved mitochondrial function, and decreased ROS, further inhibiting the ferroptosis of VECs. Dex alleviated the permeability of vessels by reducing ferroptosis and enhanced the intercellular junction of VECs.

Conclusion

Dex protects vascular leakage following sepsis by inhibiting ferroptosis. The mechanism is mainly related to metabolic reprogramming via Nrf2 up-regulation and inhibition of mitochondrial fission.