High-dose Vitamin C injection ameliorates against sepsis-induced myocardial injury by anti-apoptosis, anti-inflammatory and pro-autophagy through regulating MAPK, NF-κB and PI3K/AKT/mTOR signaling pathways in rats

AIMS

This study aimed to evaluate the effects of VC on SIMI in rats.

METHODS

In this study, the survival rate of high dose VC for SIMI was evaluated within 7 days. Rats were randomly assigned to three groups: Sham group, CLP group, and high dose VC (500 mg/kg i.v.) group. The animals in each group were treated with drugs for 1 day, 3 days or 5 days, respectively. Echocardiography, myocardial enzymes and HE were used to detect cardiac function. IL-1β, IL-6, IL-10 and TNF-α) in serum were measured using ELISA kits. Western blot was used to detect proteins related to apoptosis, inflammation, autophagy, MAPK, NF-κB and PI3K/Akt/mTOR signaling pathways.

RESULTS

High dose VC improved the survival rate of SIMI within 7 days. Echocardiography, HE staining and myocardial enzymes showed that high-dose VC relieved SIMI in rats in a time-dependent manner. And compared with CLP group, high-dose VC decreased the expressions of pro-apoptotic proteins, while increased the expression of anti-apoptotic protein. And compared with CLP group, high dose VC decreased phosphorylation levels of Erk1/2, P38, JNK, NF-κB and IKK α/β in SIMI rats. High dose VC increased the expression of the protein Beclin-1 and LC3-II/LC3-I ratio, whereas decreased the expression of P62 in SIMI rats. Finally, high dose VC attenuated phosphorylation of PI3K, AKT and mTOR compared with the CLP group.

SIGNIFICANCE

Our results showed that high dose VC has a good protective effect on SIMI after continuous treatment, which may be mediated by inhibiting apoptosis and inflammatory, and promoting autophagy through regulating MAPK, NF-κB and PI3K/AKT/mTOR pathway.

Novel insights into the regulatory role of N6-methyladenosine methylation modified autophagy in sepsis

Sepsis is defined as a life-threatening organ dysfunction caused by a dysregulated host response to infection. It is characterized by high morbidity and mortality and one of the major diseases that seriously hang over global human health. Autophagy is a crucial regulator in the complicated pathophysiological processes of sepsis. The activation of autophagy is known to be of great significance for protecting sepsis induced organ dysfunction. Recent research has demonstrated that N6-methyladenosine (m6A) methylation is a well-known post-transcriptional RNA modification that controls epigenetic and gene expression as well as a number of biological processes in sepsis. In addition, m6A affects the stability, export, splicing and translation of transcripts involved in the autophagic process. Although it has been suggested that m6A methylation regulates the biological metabolic processes of autophagy and is more frequently seen in the progression of sepsis pathogenesis, the underlying molecular mechanisms of m6A-modified autophagy in sepsis have not been thoroughly elucidated. The present article fills this gap by providing an epigenetic review of the processes of m6A-modified autophagy in sepsis and its potential role in the development of novel therapeutics.

Xuebijing injection protects sepsis induced myocardial injury by mediating TLR4/NF-κB/IKKα and JAK2/STAT3 signaling pathways

OBJECTIVE

Compelling evidence has demonstrated that Xuebijing (XBJ) exerted protective effects against SIMI. The aims of this study were to investigate whether TLR4/IKKα-mediated NF-κB and JAK2/STAT3 pathways were involved in XBJ's cardio-protection during sepsis and the mechanisms.

METHODS

In this study, rats were randomly assigned to three groups: Sham group; CLP group; XBJ group. Rats were treated with XBJ or sanitary saline after CLP. Echocardiography, myocardial enzymes and HE were used to detect cardiac function. IL-1β, IL-6 and TNF-α in serum were measured using ELISA kits. Cardiomyocyte apoptosis were tested by TUNEL staining. The protein levels of Bax, Bcl-2, Bcl-xl, Cleaved-Caspase 3, Cleaved-Caspase 9, Cleaved-PARP, TLR4, p-NF-κB, p-IKKα, p-JAK2 and p-STAT3 in the myocardium were assayed by western blotting. And finally, immunofluorescence was used to assess the level of p-JAK2 and p-STAT3 in heart tissue.

RESULTS

The results of echocardiography, myocardial enzyme and HE test showed that XBJ could significantly improve SIMI. The IL-1β, IL-6 and TNF-α levels in the serum were markedly lower in the XBJ group than in the CLP group (p<0.05). TUNEL staining's results showed that XBJ ameliorated CLP-induced cardiomyocyte apoptosis. Meanwhile, XBJ downregulated the protein levels of Bax, Cleaved-Caspase 3, Cleaved-Caspase 9, Cleaved-PARP, TLR4, p-NF-κB, p-IKKα, p-JAK2 and p-STAT3, as well as upregulated the protein levels of Bcl-2, Bcl-xl (p <0.05).

CONCLUSIONS

In here, we observed that XBJ's cardioprotective advantages may be attributable to its ability to suppress inflammation and apoptosis via inhibiting the TLR4/ IKKα-mediated NF-κB and JAK2/STAT3 pathways during sepsis.

Xuebijing injection protects against sepsis induced myocardial injury by regulating apoptosis and autophagy via mediation of PI3K/AKT/mTOR signaling pathway in rats

OBJECTIVE

Apoptosis and autophagy are significant factors of sepsis induced myocardial injury (SIMI). XBJ improves SIMI by PI3K/AKT/mTOR pathway. Present study is devised to explore the protective mechanism of XBJ in continuous treatment of SIMI caused by CLP.

METHODS

Rat survival was first recorded within 7 days. Rats were randomly assigned to three groups: Sham group, CLP group, and XBJ group. The animals in each group were divided into 12 h group, 1 d, 2 d, 3 d and 5 d according to the administration time of 12 hours, 1 day, 2 days, 3 days or 5 days, respectively. Echocardiography, myocardial injury markers and H&E staining were used to detect cardiac function and injury. IL-1β, IL-6 and TNF-α in serum were measured using ELISA kits. Cardiomyocyte apoptosis was assayed by TUNEL staining. Apoptosis and autophagy related proteins regulated by the PI3K/AKT/mTOR signaling pathway were tested using western blot.

RESULTS

XBJ increased the survival rate in CLP-induced septic Rat. First of all, the results of echocardiography, H&E staining and myocardial injury markers (cTnI, CK, and LDH levels) showed that XBJ could effectively improve the myocardial injury caused by CLP with the increase of treatment time. Moreover, XBJ significantly decreased the levels of serum inflammatory cytokines IL-1β, IL-6 and TNF-α in SIMI rats. Meanwhile, XBJ downregulated the expression of apoptosis-related proteins Bax, Cleaved-Caspase 3, Cleaved-Caspase 9, Cytochrome C and Cleaved-PARP, while upregulated the protein levels of Bcl-2 in SIMI rats. And, XBJ upregulated the expression of autophagy related protein Beclin-1 and LC3-II/LC3-I ratio in SIMI rats, whereas downregulated the expression of P62. Finally, XBJ administration downregulated the phosphorylation levels of proteins PI3K, AKT and mTOR in SIMI rats.

CONCLUSIONS

Our results showed that XBJ has a good protective effect on SIMI after continuous treatment, and it was speculated that it might be through inhibiting apoptosis and promoting autophagy via, at least partially, activating PI3K/AKT/mTOR pathway in the early stage of sepsis, as well as promoting apoptosis and inhibiting autophagy via suppressing PI3K/AKT/mTOR pathway in the late stage of sepsis.

Research Progress on the Mechanism of Sepsis Induced Myocardial Injury

Sepsis is an abnormal condition with multiple organ dysfunctions caused by the uncontrolled infection response and one of the major diseases that seriously hang over global human health. Besides, sepsis is characterized by high morbidity and mortality, especially in intensive care unit (ICU). Among the numerous subsequent organ injuries of sepsis, myocardial injury is one of the most common complications and the main cause of death in septic patients. To better manage septic inpatients, it is necessary to understand the specific mechanisms of sepsis induced myocardial injury (SIMI). Therefore, this review will elucidate the pathophysiology of SIMI from the following certain mechanisms: apoptosis, mitochondrial damage, autophagy, excessive inflammatory response, oxidative stress and pyroptosis, and outline current therapeutic strategies and potential approaches in SIMI.