Distinct effects of Nampt inhibition on mild and severe models of lipopolysaccharide-induced myocardial impairment

Mesenchymal Stem Cells Alleviate Acute Liver Failure through Regulating Hepatocyte Apoptosis and Macrophage Polarization

BACKGROUND AND AIMS

Acute liver failure (ALF) is a life-threatening clinical problem with limited treatment options. Administration of human umbilical cord mesenchymal stem cells (hUC-MSCs) may be a promising approach for ALF. This study aimed to explore the role of hUC-MSCs in the treatment of ALF and the underlying mechanisms.

METHODS

A mouse model of ALF was induced by lipopolysaccharide and d-galactosamine administration. The therapeutic effects of hUC-MSCs were evaluated by assessing serum enzyme activity, histological appearance, and cell apoptosis in liver tissues. The apoptosis rate was analyzed in AML12 cells. The levels of inflammatory cytokines and the phenotype of RAW264.7 cells co-cultured with hUC-MSCs were detected. The C-Jun N-terminal kinase/nuclear factor-kappa B signaling pathway was studied.

RESULTS

The hUC-MSCs treatment decreased the levels of serum alanine aminotransferase and aspartate aminotransferase, reduced pathological damage, alleviated hepatocyte apoptosis, and reduced mortality in vivo. The hUC-MSCs co-culture reduced the apoptosis rate of AML12 cells in vitro. Moreover, lipopolysaccharide-stimulated RAW264.7 cells had higher levels of tumor necrosis factor-α, interleukin-6, and interleukin-1β and showed more CD86-positive cells, whereas the hUC-MSCs co-culture reduced the levels of the three inflammatory cytokines and increased the ratio of CD206-positive cells. The hUC-MSCs treatment inhibited the activation of phosphorylated (p)-C-Jun N-terminal kinase and p-nuclear factor-kappa B not only in liver tissues but also in AML12 and RAW264.7 cells co-cultured with hUC-MSCs.

CONCLUSIONS

hUC-MSCs could alleviate ALF by regulating hepatocyte apoptosis and macrophage polarization, thus hUC-MSC-based cell therapy may be an alternative option for patients with ALF.

Protective Role of lncRNA TTN-AS1 in Sepsis-Induced Myocardial Injury Via miR-29a/E2F2 Axis

OBJECTIVE

Approximately 50% of patients with sepsis encounter myocardial injury. The mortality of septic patients with cardiac dysfunction (approx. 70%) is much higher than that of patients with sepsis only (20%). A large number of studies have suggested that lncRNA TTN-AS1 promotes cell proliferation in a variety of diseases. This study delves into the function and mechanism of TTN-AS1 in sepsis-induced myocardial injury in vitro and in vivo.

METHODS

LPS was used to induce sepsis in rats and H9c2 cells. Cardiac function of rats was assessed by an ultrasound system. Myocardial injury was revealed by hematoxylin-eosin (H&E) staining. Gain and loss of function of TTN-AS1, miR-29a, and E2F2 was achieved in H9c2 cells before LPS treatment. The expression levels of inflammatory cytokines and cTnT were monitored by ELISA. The expression levels of cardiac enzymes as well as reactive oxygen species (ROS) activity and mitochondrial membrane potential (MMP) were measured using the colorimetric method. The expression levels of TTN-AS1, miR-29a, E2F2, and apoptosis-related proteins were measured by RT-qPCR and/or western blotting. The proliferation and apoptosis of H9c2 cells were separately detected by CCK-8 and flow cytometry. Luciferase reporter assay was used to verify the targeting relationships among TTN-AS1, miR-29a and E2F2, and RIP assay was further used to confirm the binding between miR-29a and E2F2.

RESULTS

TTN-AS1 was lowly expressed, while miR-29a was overexpressed in the cell and animal models of sepsis. Overexpression of TTN-AS1 or silencing of miR-29a reduced the expression levels of CK, CK-MB, LDH, TNF-B, IL-1B, and IL-6 in the supernatant of LPS-induced H9c2 cells, attenuated mitochondrial ROS activity, and enhanced MMP. Consistent results were observed in septic rats injected with OE-TTN-AS1. Knockdown of TTN-AS1 or overexpression of miR-29a increased LPS-induced inflammation and injury in H9c2 cells. TTN-AS1 regulated the expression of E2F2 by targeting miR-29a. Overexpression of miR-29a or inhibition of E2F2 abrogated the suppressive effect of TTN-AS1 overexpression on myocardial injury.

CONCLUSION

This study indicates TTN-AS1 attenuates sepsis-induced myocardial injury by regulating the miR-29a/E2F2 axis and sheds light on lncRNA-based treatment of sepsis-induced cardiomyopathy.

Salidroside attenuates acute lung injury via inhibition of inflammatory cytokine production

Acute lung injury is a fatal condition characterized by excessive inflammation responses. Salidroside, the active constituent of Rhodiola rosea, possesses properties including anti-oxidation, anti-aging, anti-inflammatory, anti-hypoxia, and anti-cancer activities. In the present study, Salidroside attenuated acute lung injury via inhibition of inflammatory cytokine production. Rats pre-treated with Salidroside showed attenuated lipopolysaccharide (LPS)-induced pathological damage and suppressed tumor necrosis factor-alpha (TNFα) and interleukin 6 (IL-6) secretion in the lung. Furthermore, flow cytometry showed that Salidroside reduced the production of TNFα and IL-6 in NR8383 alveolar macrophages. These findings suggest that Salidroside may attenuate LPS-induced acute lung injury.

Anti-Apoptotic Role of Sanhuang Xiexin Decoction and Anisodamine in Endotoxemia

Endotoxemia is characterized by initial uncontrollable inflammation, terminal immune paralysis, significant cell apoptosis and tissue injury, which can aggravate or induce multiple diseases and become one of the complications of many diseases. Therefore, anti-inflammatory and anti-apoptotic therapy is a valuable strategy for the treatment of endotoxemia-induced tissue injury. Traditional Chinese medicine exhibits great advantages in the treatment of endotoxemia. In this review, we have analyzed and summarized the active ingredients and their metabolites of Sanhuang Xiexin Decoction, a famous formula in endotoxemia therapy. We then have summarized the mechanisms of Sanhuang Xiexin Decoction against endotoxemia and its mediated tissue injury. Furthermore, silico strategy was used to evaluate the anti-apoptotic mechanism of anisodamine, a well-known natural product that widely used to improve survival in patients with septic shock. Finally, we also have summarized other anti-apoptotic natural products as well as their therapeutic effects on endotoxemia and its mediated tissue injury.

LncRNA CYTOR attenuates sepsis-induced myocardial injury via regulating miR-24/XIAP

This work aims to investigate the function and mechanism of long non-coding RNA (lncRNA) cytoskeleton regulator RNA (CYTOR) in myocardial injury induced by sepsis. The sepsis-induced myocardial injury model in mice was established by intraperitoneal injection of LPS (10 mg/kg) in vivo, and cardiomyocyte H9c2 was treated with LPS to mimic sepsis in vitro. CYTOR expression and miR-24 expression were detected by qRT-PCR. After up-regulation or down-regulation of CYTOR and miR-24 expression in the H9c2 cells, and the viability of the cells was detected via MTT assay, and cell apoptosis was detected by TUNEL assay. Western blot was applied to determine the expression level of caspase 3, Bax and X-chromosome-linked inhibitor of apoptosis (XIAP). Interaction between CYTOR and miR-24 was determined by bioinformatics analysis, RT-PCR and dual luciferase reporter assay. Interaction between miR-24 and XIAP was determined through bioinformatics analysis, RT-PCR, western blot and dual luciferase reporter assay. CYTOR was markedly down-regulated. CYTOR interacted with miR-24, and negatively regulated its expression level. Over-expression of CYTOR or transfection of miR-24 inhibitors significantly promoted viability and inhibited apoptosis of H9c2 cells, while the knockdown of CYTOR and transfection of miR-24 mimics had opposite effects. CYTOR suppressed the expression level of apoptosis-related proteins, but miR-24 increased them. miR-24 directly targeted the 3'UTR of XIAP, and suppressed it, and XIAP was modulated indirectly by CYTOR. Down-regulation of CYTOR aggravates sepsis-induced cardiac injury via regulating miR-24 and XIAP.

Exogenous nicotinamide adenine dinucleotide administration alleviates ischemia/reperfusion-induced oxidative injury in isolated rat hearts via Sirt5-SDH-succinate pathway

The metabolic disorder of succinate in myocardial tissue during ischemia-reperfusion can lead to the myocardial oxidative injury. The activation of succinate dehydrogenase (SDH) plays a vital role in the process. Silent information regulator 5 (Sirt5), a nicotinamide adenine dinucleotide (NAD)-dependent desuccinylase, desuccinylates and inactivates SDH thus exerting a protective effect on the myocardium. This research was designed to investigate whether exogenous NAD protects the myocardium from the ischemia-reperfusion-induced oxidative injury through regulating Sirt5-SDH pathway and succinate metabolism. We first found that myocardial total NAD level was remarkably increased with NAD treatment (10 mg/kg) for 14 days. NAD administration significantly decreased the lactate dehydrogenase (LDH) level in coronary leakage, decreased the malondialdehyde (MDA) level and increased the reduced glutathione/oxidized glutathione disulfide ratio (GSH/GSSG) in myocardial tissue. In addition, NAD treatment effectively attenuated the depression of cardiac function in the isolated rat hearts after ischemia-reperfusion. Furthermore, we found that exogenous NAD attenuated the succinate accumulation during ischemia and decreased its depleting rate during reperfusion. We also found that NAD administration had no obvious effects on myocardial Sirt5 and SDH-a expressions. However, the results of immunofluorescence showed that Sirt5 and SDH-a interacted in ischemia-reperfused myocardium. Utilizing co-immunoprecipitation method, we found that NAD administration promoted the Sirt5 and SDH-a interaction and decreased the succinylation level of SDH-a. These results implied that exogenous NAD administration promoted Sirt5-mediated SDH-a desuccinylation and decreased the activity of SDH-a, which attenuated the succinate accumulation during ischemia and its depleting rate during reperfusion and finally alleviated reactive oxygen species generation.

Pinelliae Rhizoma Praeparatum Involved in the Regulation of Bile Acids Metabolism in Hepatic Injury

Pinelliae Rhizoma Praeparatum (PRP) as traditional Chinese medicine had been used for hepatic diseases in combinative forms. However, the effect of PRP was not clear when used alone. So to explore the hepatoprotective/hepatotoxin of PRP is necessary. The activities of PRP were investigated in acetaminophen-induced hepatic injury mice. Liver function markers, hepatic oxidative stress markers were evaluated. Bile acids metabolic transports and nuclear factor erythroid 2-related factor 2 (Nrf2) were detected. As a drug for the treatment of liver diseases, PRP slightly restored the parameters towards normal in model mice only in low dosage, and also had no antioxidant activity and regulate Nrf2. Cholestasis was significantly elevated in model mice when pretreatment with routine or high dosage of PRP, but had no effect on normal mice. Bile salt export pump (Bsep) and multidrug resistance-associated protein 2 (Mrp2) in model mice were markedly increased when pretreatment with low dose PRP, but significantly decreased when pretreatment in routine or high dosage. Mrp3 was significantly induced in model mice after pretreatment of PRP. But the adjustment effect to bile acids transporters by PRP was not significant in normal mice. These results reveal that PRP has the different effects on bile acids transporter in hepatic injury mice, and therefore, the dosage of PRP need to be paid attention to when it is used in clinical hepatic injury.

Influence of lipopolysaccharides on autophagy and inflammation in pancreatic islet cells of mice fed by high-fat diet

The aim of this study was to confirm whether chronic low-grade inflammation could induce autophagy and damage in islet cells. The high-fat diet (HF) and low-dose lipopolysaccharides (LPS) were used to simulate chronic inflammation. Islet function was observed, the expression of autophagy-related proteins and the activity of glucose synthase kinase 3β (GSK-3β) were detected, and the role of autophagy in islet injury induced by inflammation was explored. Higher blood glucose was observed in HF group and LPS group compared with control (C) group, and there was no significant difference between LPS group and LiCl group. The apoptotic pancreatic islet cells in the LPS group were higher than in the HF and C groups, and the in the LiCl group they were higher than in the C group and lower than in the LPS group. Compared with the C group, LC3II/I ratio in the HF group was increased ( P < 0.05), in LPS and LiCl groups it was lower than in the HF group, and in LiCl group it was higher than in the LPS group. There was no significant difference between HF group and C group with regard to the ratio of p-GSK-3β/GSK-3β, but in the LiCl group it was higher than in the LPS group. The results demonstrated that low-grade inflammation might cause autophagy flux impaired through activation of GSK-3β, and induced islet cells damage. LiCl could play a role in protecting islet cells through autophagy enhancement.

Salidroside suppressing LPS-induced myocardial injury by inhibiting ROS-mediated PI3K/Akt/mTOR pathway in vitro and in vivo

The purpose of the present study was to investigate the effect of salidroside (Sal) on myocardial injury in lipopolysaccharide (LPS)‐induced endotoxemic in vitro and in vivo. SD rats were randomly divided into five groups: control group, LPS group (15 mg/kg), LPS plus dexamethasone (2 mg/kg), LPS plus Sal groups with different Sal doses (20, 40 mg/kg). Hemodynamic measurement and haematoxylin and eosin staining were performed. Serum levels of creatine kinase (CK), lactate dehydrogenase, the activities of the antioxidant enzymes catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GSH‐px), glutathione, tumour necrosis factor‐α (TNF‐α), interleukin‐6 (IL‐6), and interleukin‐1β (IL‐1β) were measured after the rats were killed. iNOS, COX‐2, NF‐κB and PI3K/Akt/mTOR pathway proteins were detected by Western blot. In vitro, we evaluated the protective effect of Sal on rat embryonic heart‐derived myogenic cell line H9c2 induced by LPS. Reactive oxygen species (ROS) in H9c2 cells was measured by flow cytometry, and the activities of the antioxidant enzymes CAT, SOD, GSH‐px, glutathione‐S‐transferase, TNF‐α, IL‐6 and IL‐1β in cellular supernatant were measured. PI3K/Akt/mTOR signalling was examined by Western blot. As a result, Sal significantly attenuated the above indices. In addition, Sal exerts pronounced cardioprotective effect in rats subjected to LPS possibly through inhibiting the iNOS, COX‐2, NF‐κB and PI3K/Akt/mTOR pathway in vivo. Furthermore, the pharmacological effect of Sal associated with the ROS‐mediated PI3K/Akt/mTOR pathway was proved by the use of ROS scavenger, N‐acetyl‐l‐cysteine, in LPS‐stimulated H9C2 cells. Our results indicated that Sal could be a potential therapeutic agent for the treatment of cardiovascular disease.

The sensitivity of adipose tissue visfatin mRNA expression to lipopolysaccharide-induced endotoxemia is increased by ovariectomy in female rats

Visfatin plays an important role in inflammatory and metabolic conditions. In this study, the effects of septic stress on the serum, white-adipose-tissue (WAT), and liver visfatin levels of male and female rats were examined. Both gonadally intact (sham) and ovariectomized (OVX) female rats were used in order to evaluate the effects of the gonadal hormonal milieu on visfatin responses. Under the saline-injected conditions, the serum visfatin levels and the hepatic, subcutaneous, and visceral WAT visfatin mRNA levels of the OVX and sham rats did not differ. The serum visfatin levels and the subcutaneous, visceral WAT, and hepatic visfatin mRNA levels of both male and female rats were increased by the injection of a septic dose (5mg/kg) of LPS. At 6h after the injection of LPS, the WAT visfatin mRNA levels of the OVX rats were higher than those of the sham rats, whereas the serum visfatin levels and hepatic visfatin mRNA levels of the two groups did not differ. In the cultured visceral WAT, visfatin antagonist (FK-866) attenuated the LPS-induced up-regulations of pro-inflammatory cytokines (IL-1β, IL-6, and TNF-α). The pathophysiological roles of visfatin under septic conditions remain to be clarified. In addition, the precise mechanisms responsible for the increased WAT visfatin expression seen after ovariectomy and the effects of such changes should also be clarified.

Melatonin attenuates sepsis-induced cardiac dysfunction via a PI3K/Akt-dependent mechanism

Myocardial dysfunction is an important manifestation of sepsis. Previous studies suggest that melatonin is protective against sepsis. In addition, activation of the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) signaling pathway has been reported to be beneficial in sepsis. However, the role of PI3K/Akt signaling in the protective effect of melatonin against sepsis-induced myocardial dysfunction remains unclear. Here, LY294002, a PI3K inhibitor, was used to investigate the role of PI3K/Akt signaling in mediating the effects of melatonin on sepsis-induced myocardial injury. Cecal ligation and puncture (CLP) surgery was used to establish a rat model of sepsis. Melatonin was administrated to rats intraperitoneally (30 mg/kg). The survival rate, measures of myocardial injury and cardiac performance, serum lactate dehydrogenase level, inflammatory cytokine levels, oxidative stress level, and the extent of myocardial apoptosis were assessed. The results suggest that melatonin administration after CLP surgery improved survival rates and cardiac function, attenuated myocardial injury and apoptosis, and decreased the serum lactate dehydrogenase level. Melatonin decreased the production of the inflammatory cytokines TNF-α, IL-1β, and HMGB1, increased anti-oxidant enzyme activity, and decreased the expression of markers of oxidative damage. Levels of phosphorylated Akt (p-Akt), unphosphorylated Akt (Akt), Bcl-2, and Bax were measured by Western blot. Melatonin increased p-Akt levels, which suggests Akt pathway activation. Melatonin induced higher Bcl-2 expression and lower Bax expression, suggesting inhibition of apoptosis. All protective effects of melatonin were abolished by LY294002, the PI3K inhibitor. In conclusion, our results demonstrate that melatonin mitigates myocardial injury in sepsis via PI3K/Akt signaling activation.