Cardiomyocyte death in sepsis: Mechanisms and regulation (Review)

Roles and Therapeutic Targeting of Exosomes in Sepsis-Induced Cardiomyopathy

Sepsis-induced cardiomyopathy (SICM) is a complex and fatal manifestation of sepsis, characterised by myocardial dysfunction that exacerbates the clinical prognosis in septic patients. While the pathophysiology of SICM remains incompletely understood, emerging evidence highlights the multifaceted functions of exosomes, small membrane-bound extracellular vesicles, in mediating the inflammatory responses and cardiac dysfunction involved in this condition. During sepsis, exosomes are secreted by various cells, such as cardiomyocytes, endothelial cells and macrophages, which serve as critical messengers, transferring proteins, lipids and RNA molecules that influence recipient cells, thus affecting cellular functions and disease progression. This review summarises the pathophysiology of SICM and the basics of exosomes and focuses on exosome-mediated mechanisms in SICM, including their role in inflammation, oxidative stress, mitochondrial dysfunction and myocardial injury, offering novel insights into the exosome-based therapeutic strategies in SICM.

Po-Ge-Jiu-Xin decoction alleviate sepsis-induced cardiomyopathy via regulating phosphatase and tensin homolog-induced putative kinase 1 /parkin-mediated mitophagy

ETHNOPHARMACOLOGICAL RELEVANCE

Sepsis is a life-threatening systemic syndrome usually accompanied by myocardial dysfunction. Po-Ge-Jiu-Xin decoction (PGJXD), a traditional Chinese prescription medicine, has been used clinically to treat cardiovascular disease including heart failure, sepsis-induced cardiomyopathy (SIC) and even septic shock. Previous clinical studies suggested PGJXD has shown promising results in improving cardiac function and treating heart failure in sepsis. However, more research is needed to elucidate the mechanisms underlying PGJXD's therapeutic effects in sepsis-induced cardiomyopathy.

MATERIALS AND METHODS

Initially, we identified the major compounds of PGJXD through ultra-performance liquid chromatography-mass spectrometry technology analysis. We established in a SIC rat model using cecal ligation and puncture(CLP) and treated by PGJXD and levosimendan. We evaluated pathological damage by hematoxylin and eosin staining and measured serum myocardial injury biomarkers. Myocardial apoptosis was detected by Tunel staining and quantifying specific biomarker protein levels. Subsequently, we evaluated myocardium mitochondrial quality using Transmission electron microscope (TEM), antioxidant stress indexes and tissue adenosine triphosphate(ATP) content. We detected the expression of phosphatase and tensin homolog (PTEN)-induced putative kinase 1 (PINK1), parkin, LC3, and p62 using Western blotting and Quantitative real time polymerase chain reaction(qRT-PCR). (Lipopolysaccharides, LPS)-induced H9c2 cell model was established to further explore the mechanism of PGJXD on SIC. In addition to measuring cell viability, we measured mitochondrial membrane potential using JC-1 staining. Additionally, Parkin-siRNA transfected into H9c2 cells to validate whether PGJXD conducted protective effects against SIC through PINK1/Parkin-mediated mitophagy.

RESULTS

It has been demonstrated that PGJXD reduced mortality in septic rat, contributed to ameliorating myocardium injury, suppressed inflammatory response and ameliorated the myocardial apoptosis. PGJXD could also alleviate mitochondrial structural abnormality, mitigated oxidative stress injury and promoted energy synthesis in CLP models. Western blotting and qRT-PCR have further confirmed that PGJXD can activate PINK1/parkin pathway-mediated mitophagy, resulting in preserving mitochondrial quality in the myocardium. Furthermore, Parkin siRNA partially reversed the beneficial effect of PGJXD on mitochondrial fission/fusion and mitophagy in vitro. Therefore, the cardioprotective effect of PGJXD is achieved by inducing PINK1/Parkin-mediated mitophagy in maintaining mitochondrial homeostasis.

CONCLUSIONS

These results suggest that the potential therapeutic effect of PGJXD on cardiac dysfunction during sepsis and support its mechanism of targeted induction of PINK1-Parkin-mediated mitophagy.

Fermented Houttuynia cordata Juice Exerts Cardioprotective Effects by Alleviating Cardiac Inflammation and Apoptosis in Rats with Lipopolysaccharide-Induced Sepsis

BACKGROUND/OBJECTIVES

Sepsis-induced cardiac dysfunction is a major problem that often leads to severe complications and a poor prognosis. Despite the growing awareness of its impact, effective treatment options for sepsis-induced cardiac dysfunction remain limited. To date, fermented products of Houttuynia cordata (HC), known for its rich bioactive properties, have shown potential in modulating inflammatory and oxidative stress pathways. However, treatment with fermented HC juice (FHJ) in lipopolysaccharide (LPS)-induced sepsis in rats has not been investigated.

METHODS

Rats were pretreated with FHJ at doses of 200 mg/kg and 400 mg/kg for 2 weeks. After that, the rats were injected with a single dose of LPS (10 mg/kg), and 12 h after injection, they developed sepsis-induced cardiac dysfunction. Then, cardiac function, oxidative stress, inflammation, apoptosis, and cardiac injury markers were determined.

RESULTS

Pretreatment with FHJ at doses of 200 mg/kg and 400 mg/kg prevented LPS-induced cardiac dysfunction in rats by attenuating cardiac inflammation (IL-1β, TLR-4, and NF-κB levels), oxidative stress (MDA levels), and apoptosis (cleaved-caspase 3 and Bax/Bcl-2 expression) and reducing markers of cardiac injury (LDH and CK-MB levels).

CONCLUSIONS

These results suggest that FHJ could be a potential therapeutic agent for sepsis-induced heart disease.

Levosimendan for sepsis-induced myocardial dysfunction: friend or foe?

Sepsis-induced myocardial dysfunction (SIMD) involves reversible myocardial dysfunction. The use of inotropes can restore adequate cardiac output and tissue perfusion, but conventional inotropes, such as dobutamine and adrenaline, have limited efficacy in such situations. Levosimendan is a novel inotrope that acts in a catecholamine-independent manner. However, study results regarding the treatment of SIMD with levosimendan are inconsistent, and the use of levosimendan is highly controversial. In this review, we summarized the therapeutic mechanisms of levosimendan in SIMD and considered recent research on how to improve the efficacy of levosimendan in SIMD. We also analyzed the potential and limitations of levosimendan for the treatment of SIMD to provide ideas for future clinical trials and the clinical application of levosimendan in SIMD.

Dexmedetomidine regulates exosomal miR-29b-3p from macrophages and alleviates septic myocardial injury by promoting autophagy in cardiomyocytes via targeting glycogen synthase kinase 3β

Background

Our previous research suggested that dexmedetomidine (Dex) promotes autophagy in cardiomyocytes, thus safeguarding them against apoptosis during sepsis. However, the underlying mechanisms of Dex-regulated autophagy have remained elusive. This study aimed to explore the role of exosomes and how they participate in Dex-induced cardioprotection in sepsis. The underlying microRNA (miRNA) mechanisms and possible therapeutic targets for septic myocardial injury were identified.

Methods

We first collected plasma exosomes from rats with sepsis induced by caecal ligation and puncture (CLP) with or without Dex treatment, and then incubated them with H9c2 cells to observe the effect on cardiomyocytes. Subsequently, the differential expression of miRNAs in plasma exosomes from each group of rats was identified through miRNA sequencing. miR-29b-3p expression in circulating exosomes of septic or non-septic patients, as well as in lipopolysaccharide-induced macrophages after Dex treatment, was analysed by quantitative real-time polymerase chain reaction (qRT-PCR). The autophagy level of cardiomyocytes after macrophage-derived exosome treatment was assessed by an exosome tracing assay, western blotting, and an autophagic flux assay. Specific miRNA mimics and inhibitors or small interfering RNAs were used to predict and evaluate the function of candidate miRNA and its target genes by qRT-PCR, annexin V/propyl iodide staining, autophagy flux analysis, and western blotting.

Results

We found that plasma-derived exosomes from Dex-treated rats promoted cardiomyocyte autophagy and exerted antiapoptotic effects. Additionally, they exhibited a high expression of miRNA, including miR-29b-3p. Conversely, a significant decrease in miR-29b-3p was observed in circulating exosomes from CLP rats, as well as in plasma exosomes from sepsis patients. Furthermore, Dex upregulated the lipopolysaccharide-induced decrease in miR-29b-3p expression in macrophage-derived exosomes. Exosomal miR-29b-3p from macrophages is thought to be transferred to cardiomyocytes, thus leading to the promotion of autophagy in cardiomyocytes. Database predictions, luciferase reporter assays, and small interfering RNA intervention confirmed that glycogen synthase kinase 3β (GSK-3β) is a target of miR-29b-3p. miR-29b-3p promotes cardiomyocyte autophagy by inhibiting GSK-3β expression and activation.

Conclusions

These findings demonstrate that Dex attenuates sepsis-associated myocardial injury by modulating exosome-mediated macrophage-cardiomyocyte crosstalk and that the miR-29b-3p/GSK-3β signaling pathway represents a hopeful target for the treatment of septic myocardial injury.

PTX3 mediates PI3K/AKT/mTOR signaling to downregulate apoptosis and autophagy to attenuate myocardial injury in sepsis

Background

This study aimed to investigate the effect and mechanism of Pentraxin 3 (PTX3) on myocardial injury in sepsis.

Methods

Thirty male C57BL/6 mice were randomly assigned to Groups A, B, or C. Mice in Groups A and B were injected with unloaded lentivirus, while mice in Group C were injected with lentivirus encoding PTX3 overexpression. Seven days after injection, septic myocardial injury mouse models were constructed following intraperitoneal injection with LPS in Groups B and C, and mice in Group A were intraperitoneally injected with normal saline. Cardiac function was examined using echocardiography; pathological variation of myocardial cells was measured through HE staining, transmission electron microscopy, and TUNEL staining; and Western blot was used to measure the expression of PI3K/AKT/mTOR pathway-related, autophagy-related, and apoptosis-related proteins in mice myocardial cells.

Results

PTX3 significantly improved cardiac function and structure in sepsis-stricken mice, and PTX3 alleviated cardiac damage caused by sepsis. PTX3 reduced the relative protein expression of p-PI3K, p-AKT, mTOR, LC3I/II, Beclin, ATG5, Bax, Caspase-3, and Caspase-9 in septic mouse cardiomyocytes and increased the relative protein expression of Bcl-2.

Conclusion

PTX3 can attenuate myocardial injury in sepsis due to the down-regulation of apoptosis and autophagy induced by the PI3K/AKT/mTOR pathway.

N6-Methyladenosine Demethylase ALKBH5 Promotes Pyroptosis by Modulating PTBP1 mRNA Stability in LPS-Induced Myocardial Dysfunction

Objective

This study aims to investigate the mechanism by which alkB homolog 5 (ALKBH5) regulates polypyrimidine tract-binding protein 1 (PTBP1) to mediate cardiomyocyte pyroptosis in sepsis-induced myocardial injury.

Methods

Lipopolysaccharide (LPS)-exposed H9C2 cell and rat models were established to mimic septic myocardial injury both in vitro and in vivo. The mRNA and protein levels of ALKBH5 and PTBP1 in the LPS-induced cell and septic rat models were detected. CCK-8 and flow cytometry were applied to detect cell viability and pyroptosis. H&E staining was used to observe myocardial tissue damage in rats, and immunohistochemistry to analyze the expression of pyroptosis and inflammation-related proteins in rat tissues.

Results

Elevated expressions of both ALKBH5 and PTBP1 were found in the myocardial tissues of LPS-induced septic rats. ALKBH5 knockdown could restore the cell viability and cell pyroptosis inhibited by LPS, while ALKBH5 promoted PTBP1 mRNA stability by affecting its N6-methyladenosine (m6A) modification. In vivo experiments showed that PTBP1 knockdown could largely reverse the antiproliferative and pro-pyroptosis effects of ALKBH5 in LPS-exposed H9C2 cells. ALKBH5 knockdown in in vivo experiments was found to suppress the expressions of pyroptosis biomarkers and attenuate myocardial injury in septic rats.

Conclusions

ALKBH5 promoted mRNA stability and the expression of PTBP1 through m6A modification to induce pyroptosis in cardiomyocytes and ultimately aggravate sepsis-induced myocardial dysfunction.

Phospholipid transfer protein ameliorates sepsis-induced cardiac dysfunction through NLRP3 inflammasome inhibition

Cardiomyocyte pyroptosis is a primary contributor to sepsis-induced cardiac dysfunction (SICD). Recombinant phospholipid transfer protein (PLTP) have been demonstrated to possess anti-inflammatory and antiseptic properties. However, the effect of PLTP on SICD remains unknown. In this study, we established the in vivo and in vitro sepsis model with the recombinant PLTP treatment. The survival rates of mice, mouse cardiac function, cell viability, the protein level of proinflammatory cytokine, and lactate dehydrogenase level were evaluated. The cardiomyocyte pyroptotic changes were observed. The distribution of PLTP and NOD-like receptor thermal protein domain associated protein 3 (NLRP3) in mouse myocardial tissue and expression of PLTP, apoptosis associated speck like protein containing a CARD (ASC), NLRP3, caspase-1, interleukin (IL)-1β, and Gasdermin D (GSDMD) were detected. PLTP ameliorated the cecal ligation and puncture-induced mouse survival rate decrease and cardiac dysfunction, inhibited the IL-1β, IL-18, and tumor necrosis factor (TNF)-α release, and blocked the NLRP3 inflammasome/GSDMD signaling pathway in septic mice. In vitro, PLTP reversed the lipopolysaccharide-induced cardiomyocyte pyroptosis, expression of IL-1β, IL-6, TNF-α, and activation of the NLRP3 inflammasome/GSDMD signal pathway. Moreover, PLTP could bind to NLRP3 and negatively regulate the activity of the NLRP3 inflammasome/GSDMD signal pathway. This study demonstrated that PLTP can ameliorate SICD by inhibiting inflammatory responses and cardiomyocyte pyroptosis by blocking the activation of the NLRP3 inflammasome/GSDMD signaling pathway.

Molecular hydrogen attenuates sepsis-induced cardiomyopathy in mice by promoting autophagy

BACKGROUND

Approximately 40 to 60% of patients with sepsis develop sepsis-induced cardiomyopathy (SIC), which is associated with a substantial increase in mortality. We have found that molecular hydrogen (H2) inhalation improved the survival rate and cardiac injury in septic mice. However, the mechanism remains unclear. This study aimed to explore the regulatory mechanism by which hydrogen modulates autophagy and its role in hydrogen protection of SIC.

METHODS

Cecal ligation and puncture (CLP) was used to induce sepsis in adult C57BL/6J male mice. The mice were randomly divided into 4 groups: Sham, Sham + 2% hydrogen inhalation (H2), CLP, and CLP + H2 group. The 7-day survival rate was recorded. Myocardial pathological scores were calculated. Myocardial troponin I (cTnI) levels in serum were detected, and the levels of autophagy- and mitophagy-related proteins in myocardial tissue were measured. Another four groups of mice were also studied: CLP, CLP + Bafilomycin A1 (BafA1), CLP + H2, and CLP + H2 + BafA1 group. Mice in the BafA1 group received an intraperitoneal injection of the autophagy inhibitor BafA1 1 mg/kg 1 h after operation. The detection indicators remained the same as before.

RESULTS

The survival rate of septic mice treated with H2 was significantly improved, myocardial tissue inflammation was improved, serum cTnI level was decreased, autophagy flux was increased, and mitophagy protein content was decreased (P < 0.05). Compared to the CLP + H2 group, the CLP + H2 + BafA1 group showed a decrease in autophagy level and 7-day survival rate, an increase in myocardial tissue injury and cTnI level, which reversed the protective effect of hydrogen (P < 0.05).

CONCLUSION

Hydrogen exerts protective effect against SIC, which may be achieved through the promotion of autophagy and mitophagy.

Septic Cardiomyopathy

Sepsis is defined as a life-threatening organ dysfunction caused by a dysregulated host response to infection. Sepsis-induced myocardial dysfunction represents reversible myocardial dysfunction which ultimately results in left ventricular dilatation or both, with consequent loss of contractility. Studies on septic cardiomyopathy report a wide range of prevalence ranging from 10% to 70%. Myocardial damage occurs as a result of weakened myocardial circulation, direct myocardial depression, and mitochondrial dysfunction. Mitochondrial dysfunction is the leading problem in the development of septic cardiomyopathy and includes oxidative phosphorylation, production of reactive oxygen radicals, reprogramming of energy metabolism, and mitophagy. Echocardiography provides several possibilities for the diagnosis of septic cardiomyopathy. Systolic and diastolic dysfunction of left ventricular is present in 50-60% of patients with sepsis. Right ventricular dysfunction is present in 50-55% of cases, while isolated right ventricular dysfunction is present in 47% of cases. Left ventricle (LV) diastolic dysfunction is very common in septic shock, and it represents an early biomarker, it has prognostic significance. Right ventricular dysfunction associated with sepsis patients with worse early prognosis. Global longitudinal stress and magnetic resonance imaging (MRI) of the heart are sufficiently sensitive methods, but at the same time MRI of the heart is difficult to access in intensive care units, especially when dealing with critically ill patients. Previous research has identified two biomarkers as a result of the integrated mitochondrial response to stress, and these are fibroblast growth factor-21 (FGF-21) and growth differentiation factor-15 (GDF-15). Both of the mentioned biomarkers can be easily quantified in serum or plasma, but they are difficult to be specific in patients with multiple comorbidities. Mitochondrial dysfunction is also associated with reduced levels of miRNA (microRNA), some research showed significance of miRNA in sepsis-induced myocardial dysfunction, but further research is needed to determine the clinical significance of these molecules in septic cardiomyopathy. Therapeutic options in the treatment of septic cardiomyopathy are not specific, and include the optimization of hemodynamic parameters and the use of antibiotic thera-pies with targeted action. Future research aims to find mechanisms of targeted action on the initial mechanisms of the development of septic cardiomyopathy.

Klotho activation of Nrf2 inhibits the ferroptosis signaling pathway to ameliorate sepsis-associated acute kidney injury

Background

Sepsis-associated acute kidney injury (SA-AKI) is a common complication of sepsis and greatly increases patient mortality. Recombinant human Klotho protein (Klotho) is a protective protein that can be secreted by the kidney. The aim of this study was to explore the protective effect of Klotho on SA-AKI and its molecular mechanism.

Methods

In vivo, a mouse SA-AKI model was constructed by cecum ligation perforation (CLP). In vitro, a human renal tubular cell epithelial cell line (HK2) was induced with lipopolysaccharide (LPS) in the SA-AKI model. Determine renal injury markers, inflammatory factors, oxidative stress and molecular proteins related to the ferroptosis signaling pathway.

Results

Klotho reduced the release of renal injury markers and inflammatory cytokines, decreased oxidative stress, improved renal histopathological changes, ameliorated mitochondrial damage in mouse renal tubular epithelial cells, increased HK2 cell viability and reduced reactive oxygen species (ROS) accumulation. Exogenous supplementation with Klotho increased the Klotho content in circulating blood, renal tissue and HK2 cells.

Conclusions

In the SA-AKI model, Klotho attenuated renal tissue injury, increased HK2 cell viability, decreased inflammatory factor expression and oxidative stress, restored tubular epithelial mitochondrial function, and increased its level in circulating blood, renal tissue and HK2 cells. Klotho probably exerts its protective effects by activating Nrf2 to inhibit the ferroptosis signaling pathway.

Cardiac and intestinal tissue conduct developmental and reparative processes in response to lymphangiocrine signaling

Lymphatic vessels conduct a diverse range of activities to sustain the integrity of surrounding tissue. Besides facilitating the movement of lymph and its associated factors, lymphatic vessels are capable of producing tissue-specific responses to changes within their microenvironment. Lymphatic endothelial cells (LECs) secrete paracrine signals that bind to neighboring cell-receptors, commencing an intracellular signaling cascade that preludes modifications to the organ tissue's structure and function. While the lymphangiocrine factors and the molecular and cellular mechanisms themselves are specific to the organ tissue, the crosstalk action between LECs and adjacent cells has been highlighted as a commonality in augmenting tissue regeneration within animal models of cardiac and intestinal disease. Lymphangiocrine secretions have been owed for subsequent improvements in organ function by optimizing the clearance of excess tissue fluid and immune cells and stimulating favorable tissue growth, whereas perturbations in lymphatic performance bring about the opposite. Newly published landmark studies have filled gaps in our understanding of cardiac and intestinal maintenance by revealing key players for lymphangiocrine processes. Here, we will expand upon those findings and review the nature of lymphangiocrine factors in the heart and intestine, emphasizing its involvement within an interconnected network that supports daily homeostasis and self-renewal following injury.

Polo-like kinase 1 promotes sepsis-induced myocardial dysfunction

Sepsis-induced myocardial dysfunction (SIMD) is the main cause of mortality in sepsis. In this study, we identified Polo-like kinase 1 (Plk-1) is a promoter of SIMD. Plk-1 expression was increased in lipopolysaccharide (LPS)-treated mouse hearts and neonatal rat cardiomyocytes (NRCMs). Inhibition of Plk-1 either by heterozygous deletion of Plk-1 or Plk-1 inhibitor BI 6727 alleviated LPS-induced myocardial injury, inflammation, cardiac dysfunction, and thereby improved the survival of LPS-treated mice. Plk-1 was identified as a kinase of inhibitor of kappa B kinase alpha (IKKα). Plk-1 inhibition impeded NF-κB signal pathway activation in LPS-treated mouse hearts and NRCMs. Augmented Plk-1 is thus essential for the development of SIMD and is a druggable target for SIMD.

Role of toll-like receptor-mediated pyroptosis in sepsis-induced cardiomyopathy

Sepsis, a life-threatening dysregulated status of the host response to infection, can cause multiorgan dysfunction and mortality. Sepsis places a heavy burden on the cardiovascular system due to the pathological imbalance of hyperinflammation and immune suppression. Myocardial injury and cardiac dysfunction caused by the aberrant host responses to pathogens can lead to cardiomyopathy, one of the most critical complications of sepsis. However, many questions about the specific mechanisms and characteristics of this complication remain to be answered. The causes of sepsis-induced cardiac dysfunction include abnormal cardiac perfusion, myocardial inhibitory substances, autonomic dysfunction, mitochondrial dysfunction, and calcium homeostasis dysregulation. The fight between the host and pathogens acts as the trigger for sepsis-induced cardiomyopathy. Pyroptosis, a form of programmed cell death, plays a critical role in the progress of sepsis. Toll-like receptors (TLRs) act as pattern recognition receptors and participate in innate immune pathways that recognize damage-associated molecular patterns as well as pathogen-associated molecular patterns to mediate pyroptosis. Notably, pyroptosis is tightly associated with cardiac dysfunction in sepsis and septic shock. In line with these observations, induction of TLR-mediated pyroptosis may be a promising therapeutic approach to treat sepsis-induced cardiomyopathy. This review focuses on the potential roles of TLR-mediated pyroptosis in sepsis-induced cardiomyopathy, to shed light on this promising therapeutic approach, thus helping to prevent and control septic shock caused by cardiovascular disorders and improve the prognosis of sepsis patients.

Estradiol as the Trigger of Sirtuin-1-Dependent Cell Signaling with a Potential Utility in Anti-Aging Therapies

Aging entails the inevitable loss of the structural and functional integrity of cells and tissues during the lifetime. It is a highly hormone-dependent process; although, the exact mechanism of hormone involvement, including sex hormones, is unclear. The marked suppression of estradiol synthesis during menopause suggests that the hormone may be crucial in maintaining cell lifespan and viability in women. Recent studies also indicate that the same may be true for men. Similar anti-aging features are attributed to sirtuin 1 (SIRT1), which may possibly be linked at the molecular level with estradiol. This finding may be valuable for understanding the aging process, its regulation, and possible prevention against unhealthy aging. The following article summarizes the initial studies published in this field with a focus on age-associated diseases, like cancer, cardiovascular disease and atherogenic metabolic shift, osteoarthritis, osteoporosis, and muscle damage, as well as neurodegenerative and neuropsychiatric diseases.

Zataria multiflora and its constituent, carvacrol, counteract sepsis-induced aortic and cardiac toxicity in rat: Involvement of nitric oxide and oxidative stress

BACKGROUND

Zataria multiflora and carvacrol showed various pharmacological properties including anti-inflammatory and anti-oxidant effects. However, up to now no studies have explored its potential benefits in ameliorating sepsis-induced aortic and cardiac injury. Thus, this study aimed to investigate the effects of Z. multiflora and carvacrol on nitric oxide (NO) and oxidative stress indicators in lipopolysaccharide (LPS)-induced aortic and cardiac injury.

METHODS

Adult male Wistar rats were assigned to: Control, lipopolysaccharide (LPS) (1 mg/kg, intraperitoneal (i.p.)), and Z. multiflora hydro-ethanolic extract (ZME, 50-200 mg/kg, oral)- and carvacrol (25-100 mg/kg, oral)-treated groups. LPS was injected daily for 14 days. Treatment with ZME and carvacrol started 3 days before LPS administration and treatment continued during LPS administration. At the end of the study, the levels of malondialdehyde (MDA), NO, thiols, and antioxidant enzymes were evaluated.

RESULTS

Our findings showed a significant reduction in the levels of superoxide dismutase (SOD), catalase (CAT), and thiols in the LPS group, which were restored by ZME and carvacrol. Furthermore, ZME and carvacrol decreased MDA and NO in cardiac and aortic tissues of LPS-injected rats.

CONCLUSIONS

The results suggest protective effects of ZME and carvacrol on LPS-induced cardiovascular injury via improved redox hemostasis and attenuated NO production. However, additional studies are needed to elucidate the effects of ZME and its constituents on inflammatory responses mediated by LPS.

Dysbiosis of Gut Microbiota Contributes to Uremic Cardiomyopathy via Induction of IFNγ-Producing CD4+ T Cells Expansion

Uremic cardiomyopathy (UCM) correlates with chronic kidney disease (CKD)-induced morbidity and mortality. Gut microbiota has been involved in the pathogenesis of certain cardiovascular disease, but the role of gut microbiota in the pathogenesis of UCM remains unknown. Here, we performed a case-control study to compare the gut microbiota of patients with CKD and healthy controls by 16S rRNA (rRNA) gene sequencing. To test the causative relationship between gut microbiota and UCM, we performed fecal microbiota transplantation (FMT) in 5/6th nephrectomy model of CKD. We found that opportunistic pathogens, particularly Klebsiella pneumoniae (K. pneumoniae), are markedly enriched in patients with CKD. FMT from CKD patients aggravated diastolic dysfunction in the mouse model. The diastolic dysfunction was associated with microbiome-dependent increases in heart-infiltrating IFNγ+ CD4+ T cells. Monocolonization with K. pneumoniae increased cardiac IFNγ+ CD4+ T cells infiltration and promoted UCM development of the mouse model. A probiotic Bifidobacterium animalis decreased the relative abundance of K. pneumoniae, reduced levels of cardiac IFNγ+ CD4+ T cells and ameliorated the severity of diastolic dysfunction in the mice. Thus, the aberrant gut microbiota in CKD patients, especially K. pneumoniae, contributed to UCM pathogenesis through the induction of heart-infiltrating IFNγ+ CD4+ T cells expansion, proposing that a Gut Microbiota-Gut-Kidney-Heart axis could play a critical role in elucidating the etiology of UCM, and suggesting that modulation of the gut bacteria may serve as a promising target for the amelioration of UCM. IMPORTANCE Uremic cardiomyopathy (UCM) correlates tightly with increased mortality in patients with chronic kidney disease (CKD), yet the pathogenesis of UCM remains incompletely understood, limiting therapeutic approaches. Our study proposed that a Gut Microbiota-Gut-Kidney-Heart axis could play a critical role in understanding etiology of UCM. There is a major need in future clinical trials of patients with CKD to explore if modulation of gut microbiota by fecal microbiota transplantation (FMT), probiotics or antibiotics can alleviate cardiac dysfunction, reduce mortality, and improve life quality.