Sepsis-associated cardiac dysfunction is controlled by small RNA molecules

Upregulation of miR‑335 exerts protective effects against sepsis‑induced myocardial injury

Septicemia is associated with excessive inflammation, oxidative stress and apoptosis, causing myocardial injury that results in high mortality and disability rates worldwide. The abnormal expression of multiple microRNAs (miRNAs/miRs) is associated with more severe sepsis‑induced myocardial injury (SIMI) and miR‑335 has been shown to protect cardiomyocytes from oxidative stress. The present study aimed to investigate the role of miR‑335 in SIMI. An SIMI model was established by cecal ligation and puncture (CLP) in mice. An miRNA‑335 precursor (pre‑miR‑335) was transfected to accelerate miR‑335 expression and an miR‑335 inhibitor (anti‑miR‑335) was used to inhibit miR‑335 expression. CLP or sham surgery was performed on pre‑miR‑335, anti‑miR‑335 and wild‑type mice and miR‑335 expression was determined by reverse transcription‑quantitative PCR. Inflammatory factors (TNF‑α, IL‑6 and IL‑10) and troponin (cTNI), brain natriuretic peptide (BNP), creatine kinase (CK), lactate dehydrogenase (LDH) and aspartate aminotransferase (AST) were assessed using commercial kits. Apoptosis was detected by flow cytometry and cardiac function was assessed using a Langendorff isolated cardiac perfusion system. miR‑335 expression was upregulated and an elevation in inflammatory factors and cTNI, BNP, CK, LDH and AST was observed. Compared with the wild‑type control group, pre‑miR‑335 mice treated with CLP exhibited significantly reduced left ventricular development pressure, maximum pressure increased reduction rates, as well as decreased levels of TNF‑α, IL‑6 and IL‑10, myocardial injury and apoptosis; by contrast, these features were amplified in CLP‑treated anti‑miR‑335 mice. In conclusion, the upregulation of miR‑335 exerted ameliorative effects on myocardial injury following sepsis and may indicate a novel therapeutic intervention for SIMI.

Diagnostic value and significance of serum miR-132 combined with miR-223 for sepsis-induced cardiomyopathy

In previous studies, miR-132 and miR-223 were considered to be involved in cellular and pathological processes of diseases. However, the role of early diagnosis and prognosis evaluation in sepsis-induced cardiomyopathy (SIC) remains unknown. The present study aimed to explore the diagnostic value of combined detection of miR-132 and miR-223 for SIC and their correlation with creatine kinase-MB (CK-MB), cardiac troponin I (cTnI), tumor necrosis factor α (TNF-α), and interleukin-6 (IL)-6. SIC patients (n=80) admitted to Tianjin Medical University General Hospital were assigned to the research group (RG), while 60 healthy participants receiving physical examinations at the same period were assigned to the control group (CG). Serum expression profiles of miR-132 and miR-223 were detected by the RT-qPCR. CK-MB and cTnI were assessed using chemiluminescence assay, and TNF-α and IL-6 by enzyme-linked immunosorbent assay (ELISA). Serum miR-132 and miR-223 levels were significantly lower in the RG than in the CG (P<0.001). The sensitivity and specificity for the diagnosis of SIC were 82.50 and 71.67% for miR-132, 95.00 and 61.67% for miR-223, as well as 86.25 and 86.67% for miR-132 combined with miR-223. Serum miR-132 and miR-223 levels were significantly higher in the survivor group than in the deceased group (P<0.001). The sensitivity and specificity for the prognosis of SIC were 85.96 and 65.22% for miR-132 combined with miR-223. Serum miR-132 and miR-223 were negatively correlated with serum CK-MB, cTnI, TNF-α, and IL-6 (P<0.001). miR-132 combined with miR-223 can be used for early diagnosis and prognostic evaluation of SIC, and the two are correlated with CK-MB, cTnI, TNF-α, and IL-6.

Non-coding RNAs and Exosomes: Their Role in the Pathogenesis of Sepsis

Sepsis is characterized as an uncontrolled host response to infection, and it represents a serious health challenge, causing excess mortality and morbidity worldwide. The discovery of sepsis-related epigenetic and molecular mechanisms could result in improved diagnostic and therapeutic approaches, leading to a reduced overall risk for affected patients. Accumulating data show that microRNAs, non-coding RNAs, and exosomes could all be considered as novel diagnostic markers for sepsis patients. These biomarkers have been demonstrated to be involved in regulation of sepsis pathophysiology. However, epigenetic modifications have not yet been widely reported in actual clinical settings, and further investigation is required to determine their importance in intensive care patients. Further studies should be carried out to explore tissue-specific or organ-specific epigenetic RNA-based biomarkers and their therapeutic potential in sepsis patients.

Characterization of Circular RNA and microRNA Profiles in Septic Myocardial Depression: a Lipopolysaccharide-Induced Rat Septic Shock Model

Septic shock with heart dysfunction is common in intensive care units. However, the mechanism underlying myocardial depression is still unclear. Whether circular RNA (circRNA) or microRNA (miRNA) profiles differ between patients with and without myocardial depression is unknown. We generated a hypodynamic septic shock model induced by lipopolysaccharide (LPS) in adolescent rats. A total of 12 rats were utilized and heart tissue from each was collected. RNA sequencing was performed on left ventricular tissue. We focused on features of circRNAs and miRNAs, predicting their function by bioinformatic analysis and constructing circRNA-associated and miRNA-associated regulatory networks in heart tissue. We detected 851 circRNAs in heart samples, and 11 showed differential expression. A total of 639 annotated miRNAs and 91 novel miRNAs were explored including 78 showing differential expression between the two groups. We then constructed the most comprehensive circRNA-associated and miRNA-associated networks to explore their regulatory relationship in septic heart tissue, and demonstrated that different networks could potentially participate in and regulate the pathological process of sepsis. Furthermore, gene ontology term enrichment indicated miRNAs, and miRNA-mRNA networks could be associated with regulation and metabolic process, or influence cellular functions. The construction of regulator networks could improve the understanding of the basic molecular mechanisms underlying myocardial depression. It will be important for future investigations to ascertain the biological mechanisms present during the development of sepsis-induced myocardial depression to influence approaches to treatment.

Gracillin inhibits apoptosis and inflammation induced by lipopolysaccharide (LPS) to alleviate cardiac injury in mice via improving miR-29a

Sepsis induces critical myocardial dysfunction, resulting in an increased mortality. Gracillin (GRA) is a natural steroidal saponin, showing strong capacities of anti-inflammation, but its pharmacological effects on lipopolysaccharide (LPS)-induced acute cardiac injury still remain unclear. In this study, we attempted to explore if GRA was effective to attenuate cardiac injury in LPS-challenged mice and the underlying mechanisms. First, we found that GRA treatments markedly up-regulated the expression of miR-29a in cardiomyocytes. LPS-induced cytotoxicity in cardiomyocytes was significantly alleviated by GRA treatment, as evidenced by the improved cell viability and reduced lactate dehydrogenase (LDH) release. In addition, LPS-triggered apoptotic cell death was clearly ameliorated in cardiomyocytes co-treated with GRA. Notably, LPS-exposed cells showed significantly reduced expression of miR-29a, while being rescued by GRA treatment. In vivo, LPS apparently impaired cardiac function in mice, which was, however, alleviated by GRA administration. In addition, GRA markedly attenuated apoptosis in hearts of LPS-challenged mice by decreasing the expression of cleaved Caspase-3. LPS-triggered inflammatory response in cardiac tissues was also suppressed by GRA through blocking nuclear factor κB (NF-κB) signaling pathway. We also found that miR-29a expression was highly reduced in hearts of LPS-treated mice but was rescued by GRA pretreatment. Besides, miR-29a mimic alleviated LPS-induced apoptosis and inflammation in cardiomyocytes; however, LPS-caused effects were further accelerated by miR-29a. Of note, the protective effects of GRA on LPS-injured cardiac tissues were significantly abrogated by miR-29a suppression. In conclusion, our findings demonstrated that GRA exerted an effective role against LPS-induced acute cardiac injury through impeding apoptosis and inflammation regulated by miR-29a.

P27 Protects Cardiomyocytes from Sepsis via Activation of Autophagy and Inhibition of Apoptosis

BACKGROUND It has been reported that p27Kip1 plays an important role not only in the inhibition of cyclin-dependent kinases but also in the regulation of autophagy under various metabolically related stress conditions, including glucose deprivation and endoplasmic reticulum stress. However, its effect on lipopolysaccharide (LPS)-induced cardiomyocyte stress in vitro remains unclear. Here, we measured the increased expression of LC3-II and visualized autophagosomes in vitro by immunofluorescent assays after treatment with a p27 fusion protein. MATERIAL AND METHODS Cardiomyocyte contractile properties were assessed by measuring cell shortening and re-lengthening. Apoptosis was evaluated by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining. Western blot, colorectal ligation puncture (CLP) surgery, silencing of Atg5 expression by small interfering RNA (siRNA), and immunofluorescent assays were also performed in this study. RESULTS After exogenous delivery of the p27 fusion protein and overexpression of p27 in LPS-induced cardiomyocytes, we found lower expressions of caspase-3 and caspase-8 and reduced positive TUNEL staining. Improved cardiomyocyte mechanical functions and reduced apoptosis were diminished after treatment with various autophagy inhibitors. Intravenous injections of p27-expressing adeno-associated virus serotype 9 (AAV9) vectors resulted in cardiac specific overexpression of p27, and echocardiography was used to assess cardiac function and structure in sepsis rat models. We observed improved cardiac function and reversed adverse ventricular remolding after the introduction of AAV9 vectors. Meanwhile, apoptosis was reduced, and expression of LC3-II was elevated in septic rat models treated with AAV9 vectors compared to controls. CONCLUSIONS The study data demonstrated that the overexpression of p27 protects cardiomyocytes from sepsis-induced cardiac depression via the activation of autophagy and inhibition of apoptosis.

Cardiac dysfunction in critical illness

PURPOSE OF REVIEW

Sepsis and septic shock are prevalent conditions that are likely to increase in prevalence in the future. Given the high mortality and morbidity associated with sepsis and sepsis-induced cardiac dysfunction, we must continue to make advances in knowledge of the complex physiologic interactions and how we may target specific mediators for potential therapeutic options in the future.

RECENT FINDINGS

Multiple biomarkers have been discovered, which when assayed in sepsis-induced cardiomyopathy predict morbidity and mortality. With increased sensitivity of echocardiography, we can diagnose subclinical cardiac dysfunction, which may have future implications for slowing or preventing progressive dysfunction.

SUMMARY

Sepsis-induced cardiomyopathy is the result of complicated interactions between the pathogen, the body's response to infection, and iatrogenic injury. Interplay between inflammatory, metabolic, and adrenergic systems results in direct and indirect myocardial injury leading to decreases in both systolic and diastolic cardiac function. As the interactions are further elucidated with additional research into other proteins and mediators, new treatment options can be researched. VIDEO ABSTRACT.

Non-coding RNA: a potential biomarker and therapeutic target for sepsis

Sepsis, a syndrome of physiologic, pathologic, and biochemical abnormalities caused by an altered systemic host response to infection, has become the main cause of death among patients admitted to the intensive care units. Recently, genome-wide expression analysis revealed that over 80% of the essential genetic elements were altered in critically ill patients. Notably, non-coding RNAs, including microRNAs, long non-coding RNAs and circular RNAs, have been proven to play essential roles in innate immunity, mitochondrial dysfunction and organ dysfunction. In this review, we introduced the biogenesis of non-coding RNAs briefly and summed up different kinds of non-coding RNAs in regulation of sepsis, which could provide a more comprehensive understanding about pathogenesis of the disease. Additionally, we summarized the limitations of current biomarkers and then recommended some non-coding RNAs as novel potential biomarkers for sepsis and sepsis-induced organ dysfunction. Besides, we also introduced some problems and challenges that need to be overcome during the clinical application of non-coding RNAs. Future research should focus on elucidating their molecular mechanisms, particularly long non-coding RNAs as well as circular RNAs and sepsis, to further understanding of the disease process. With the in-depth understanding of the mechanism of sepsis, non-coding RNAs provide a new insight into sepsis and could become the novel therapeutic targets in the future.

Pterostilbene alleviates polymicrobial sepsis-induced liver injury: Possible role of SIRT1 signaling

Liver injury occurs frequently during sepsis. Pterostilbene (Pte), a natural dimethylated analog of resveratrol from blueberries, exerts anti-inflammatory and anti-apoptotic effects in various diseases. However, the role of Pte in sepsis-induced liver injury and its underlying mechanisms remain unknown. The current study aimed to evaluate the protective effects of Pte on sepsis-induced liver injury and its potential mechanisms. Sepsis was induced using cecal ligation and puncture (CLP) in C57BL/6 mice. Mice were administered Pte (5, 10, 15mg/kg, i.p.) at 0.5h, 2h, and 8h after CLP induction. The pathological changes of the liver were evaluated using hematoxylin and eosin (H&E) staining. The serum levels of alanine transaminase (ALT) and aspartate aminotransferase (AST) were measured. The levels of tumor necrosis factor-alpha (TNF-α), interleukin (IL-6), myeloperoxidase (MPO), p38 mitogen-activated protein kinase (p38MAPK), Bax, and B-cell lymphoma 2 (Bcl-2) were also evaluated. Pte treatment attenuated the CLP-induced liver injury, as evidenced by the attenuated histopathologic injuries and the decreased serum aminotransferase levels. Pte reduced the serum inflammatory cytokine (TNF-α and IL-6) levels and hepatic mRNA levels of TNF-α and IL-6. Pte also reduced MPO activity and p38MAPK activation in the liver. Additionally, Pte significantly inhibited Bax expression and increased Bcl-2 expression. Moreover, Pte increased the expression of sirtuin-1 (SIRT1) and reduced the expression of acetylated forkhead box O1 (Ac-FoxO1), acetylated Ac-p53, and acetylated nuclear factor-kappa beta (Ac-NF-κB). However, SIRT1 small interfering RNA (siRNA) abolished Pte's effects on the expression levels of those protein. Notably, Pte improved the survival rate in septic mice. In conclusion, Pte alleviates sepsis-induced liver injury by reducing inflammatory response and inhibiting hepatic apoptosis, and the potential mechanism is associated with SIRT1 signaling activation.

Cinnamaldehyde ameliorates LPS-induced cardiac dysfunction via TLR4-NOX4 pathway: The regulation of autophagy and ROS production

Cinnamaldehyde (CA), a major bioactive compound extracted from the essential oil of Cortex Cinnamomi, exhibits anti-inflammatory activity on endotoxemia. Accumulating evidence indicates reactive oxygen species (ROS) and autophagy play a vital role in the cardiac dysfunction during endotoxemia. The aim of this study was to unveil the mechanism of CA on ROS production and autophagy during endotoxemia. Male Sprague-Dawley rats were stimulated by LPS (20mg/kg i.v.) with or without treatment of CA. Cardiac function and histopathological staining were preformed 4h after LPS stimulation. The levels of TNF-α, IL-1β and IL-6 were detected by ELISA. The expression of p-JNK, p-ERK, p-p38, TLR4, NOX4, NOX2, ATG5 and LC3 proteins were determined by Western blot. The results showed that CA inhibited cardiac dysfunction, inflammatory infiltration and the levels of TNF-α, IL-1β and IL-6 in LPS stimulated rats by blocking the TLR4, NOX4, MAPK and autophagy signalings. In order to obtain further confirmation of the mechanism of CA on endotoxemia in vitro, a limited time-course study was firstly performed by Western blot. TLR4, NOX4 and LC3 were significantly increased after 4h LPS stimulation. CA reversed the intracellular ROS production and MAPK signaling activation induced by LPS. Electron microscopy, mRFP-GFP-LC3 transfection and western blot results revealed autophagic flux were attenuated after CA treatment. The siRNA and molecular docking results suggest that CA can suppress both TLR4 and NOX4 during endotoxemia. Our data revealed that CA ameliorated LPS-induced cardiac dysfunction by inhibiting ROS production and autophagy through TLR4-NOX4 pathway.