Differential sensitivity to LPS-induced myocardial dysfunction in the isolated brown Norway and Dahl S rat hearts: roles of mitochondrial function, NF-κB activation, and TNF-α production

Acetyl-11-Keto-β-Boswellic Acid (AKBA) Prevents Lipopolysaccharide-Induced Inflammation and Cytotoxicity on H9C2 Cells

Acetyl-11-keto-beta-boswellic acid (AKBA), the major component of Boswellia serrata, exhibits anti-inflammatory activities. This in vitro study investigated the protective effects of AKBA against lipopolysaccharide (LPS)-induced cardiac dysfunction. In this study, the H9C2 cardiomyocytes were pretreated with AKBA (2.5, 5, and 10 μM for 24 h), and then cotreated with LPS for another 24 h. The MTT assay, ELISA test kits, and quantitative real-time PCR analysis assessed the cell viability, levels of proinflammatory factors (IL-β, IL-6, TNF- α, and PGE2), and the gene expression of IL-β, IL-6, TNF- α, iNOS, and COX-2, respectively. The nitric oxide (NO) and thiol levels were also measured using a biochemical assay. The results indicated that LPS exposure markedly reduced cell viability and total thiol content, but increased the inflammatory cytokines, NO metabolites, and gene expression of proinflammatory mediators in H9C2 cells. AKBA pretreatment significantly altered the mentioned factors induced by LPS. Our results demonstrated that AKBA might be a promising therapeutic agent for treating sepsis-related cardiac dysfunction in the future.

Myc is involved in Genistein protecting against LPS-induced myocarditis in vitro through mediating MAPK/JNK signaling pathway

BACKGROUND

Genistein is widely used as a pharmacological compound as well as a food additive. However, the pharmaceutical effects of Genistein on myocarditis and its potential mechanisms have not been studied in detail.

METHODS

H9c2 cells were continuously stimulated by lipopolysaccharide (LPS) for 12 h to simulate the in vitro model of myocarditis injury. DrugBank, String, and GEO dataset were used to investigate specific genes that interacting with Genistein. KEGG and GO enrichment analysis were employed to explore Myc-related signaling pathways. Biological behaviors of H9c2 cells were observed with the support of cell counting kit-8, MTT and flow cytometry. Expression levels of cytokines including TNF-α and ILs were evaluated by enzyme-linked immunosorbent assay. Western blot was applied to detect the expression of Myc and MAPK pathway related proteins.

RESULTS

Genistein alleviated the damage of H9c2 cells subjected to LPS from the perspective of elevating cells growth ability, and inhibiting cells apoptosis and inflammatory response. Through bioinformatics analysis, we identified Myc as the potential target of Genistein in myocarditis, and MAPK as the signaling pathway. Significantly, Myc was highly up-regulated in myocarditis samples. More importantly, by performing biological experiments, we discovered that Genistein relieved H9c2 cells apoptosis and inflammatory reaction which caused by LPS stimulation through inhibiting Myc expression. Additionally, the marked augmentation of p-P38 MAPK and p-JNK expression in LPS-induced cardiomyocyte model were blocked by Genistein and si-Myc.

CONCLUSIONS

Our research revealed that Myc mediated the protective effects of Genistein on H9c2 cells damage caused by LPS partly through modulation of MAPK/JNK signaling pathway.

Fulminant myocarditis: a comprehensive review from etiology to treatments and outcomes

Fulminant myocarditis (FM) is characterized by a rapid progressive decline in cardiac function and a high mortality rate. Since the first report of FM patients in the 1980s, several clinical trials and research studies have been published increasing our knowledge regarding FM. Currently, the diagnosis of FM depends on various techniques including electrocardiography, echocardiography, endomyocardial biopsy, and cardiac magnetic resonance. The development of mechanical circulation support (MCS) devices and progress in our understanding of the pathophysiological mechanisms underlying FM, treatment regimens have evolved from simple symptomatic treatment to a life support-based comprehensive treatment approach. The core mechanism underlying the development of FM is the occurrence of an inflammatory cytokine storm. This review provides a comprehensive account of the current understanding of FM pathophysiology and knowledge regarding its etiology, pathophysiology, treatments, and outcomes.

Comparison of the TLR4/NFκB and NLRP3 signalling pathways in major organs of the mouse after intravenous injection of lipopolysaccharide

Context: Lipopolysaccharide (LPS) is often used to induce immunoinflammatory reactions. TLR4/NFκB and NLRP3 signalling are major factors for inflammation. Dexamethasone (DXM) has an anti-immunoinflammatory effect. Objective: To investigate the inflammatory reaction in pathological changes of organs and the expression of inflammatory signalling during LPS infection. Materials and methods: ICR mice were divided into control group (n = 9), LPS group (n = 15) and LPS + DXM group (n = 14). LPS (10 mg/kg) was injected intravenously in LPS group and LPS + DXM group, normal saline was injected to the control group; DXM (0.5 mg/kg) was given by intragastric administration. 12 h after LPS, the blood was collected and the organs were isolated for biochemical analysis, protein expression, and morphological examination. Results: The results showed that BUN, Cre, ALT, AST in the LPS group increased distinctly by 81.42, 67.84, 40.53 and 36.05%, respectively, and CK, ALP, TP and ALB decreased by 71.37, 60.6, 12.57 and 19.73%, respectively, compared with the control group. In the morphologic observation, local necrosis in the liver, arterial vasodilation in the heart and kidney, alveolar secretions and pulmonary interstitial in the lungs, and mucosal shedding in the small and large intestines, the expression of TLR4-NFκB signalling were up-regulated distinctly whereas NLRP3 signalling was less broadly affected. DXM can decrease BUN and Cre, downregulate the expression of TLR4-NFκB signalling, but has no effect on the organ damage based on morphology. Conclusion: Acute injuries induced by LPS are extensive. The inflammatory damage in small and large intestines, liver and kidney was more severe than other organs. TLR4-NFκB signalling was the major response to LPS stress.

Mitochondrial Injury and Targeted Intervention in Septic Cardiomyopathy

Background:

Sepsis and septic shock are known to prompt multiple organ failure including cardiac contractile dysfunction, which is typically referred to as septic cardiomyopathy. Among various theories postulated for the etiology of septic cardiomyopathy, mitochondrial injury (both morphology and function) in the heart is perceived as the main culprit for reduced myocardial performance and ultimately heart failure in the face of sepsis.

Methods:

Over the past decades, ample of experimental and clinical work have appeared, focusing on myocardial mitochondrial changes and related interventions in septic cardiomyopathy.

Results and Conclusion:

Here we will briefly summarize the recent experimental and clinical progress on myocardial mitochondrial morphology and function in sepsis, and discuss possible underlying mechanisms, as well as the contemporary interventional options.

Mechanism of Metformin on LPS-Induced Bacterial Myocarditis

Aims:

Metformin is commonly used to treat type 2 diabetes mellitus; however, in recent years, it was found to play a potential role in the protection of myocardial injury. In this study, we intended to investigate whether metformin had protective effects on bacterial myocarditis.

Methods and Results:

We stimulated rat cardiac myoblast H9c2 cells with lipopolysaccharide (LPS) and administrated with metformin. The results showed that cell viability after LPS stimulation was greatly reduced. The expression levels of phosphorylated p38 mitogen-activated protein kinases (MAPK) and c-Jun N-terminal kinases (JNK), nuclear factor (NF)-κB (NF-κB), BAX, and cleaved Caspase3 were significantly increased, while the expression of antiapoptotic protein Bcl-2 showed a prominent decrease compared to control. Nevertheless, the cells activity increased remarkably after metformin administration, and the expression levels of intracellular related proteins showed the opposite trend to that of the LPS group.

Conclusion:

We demonstrate that LPS stimulation may activate intracellular MAPK/JNK and NF-κB signaling pathways and thus induce cell apoptosis. In contrast, metformin reduced apoptosis by inhibiting this signaling pathway and increasing the expression level of Bcl-2. Moreover, it was found that metformin could enhance the ability of cells to antagonize redox damage by regulating the activities of superoxide dismutase and lactate dehydrogenase and subsequently promote the recovery of cardiomyocyte function.

Effect of Shenfu injection on lipopolysaccharide (LPS)-induced septic shock in rabbits

ETHNOPHARMACOLOGICAL RELEVANCE

Shenfu injection is a popular Chinese herbal formula that has been widely used in the treatment of shock in China.

AIM OF THE STUDY

To investigate the effect of Shenfu injection on lipopolysaccharide (LPS)-induced septic shock in rabbits.

MATERIALS AND METHODS

We established a septic shock model in rabbits by administering an intravenous injection of 0.6 mg/kg LPS to anesthetized rabbit, and 15 min after LPS challenge, the rabbits were intravenously administered the Shenfu injection. In these in vivo experiments, the jugular vein of the rabbits was cannulated for LPS and drug administration, and the right common carotid artery was cannulated to record the mean arterial pressure (MAP) over a 6-h period. In addition, various serum biochemical parameters, including lactate dehydrogenase (LDH), aspartate aminotransferase (AST), glutamate transaminase (ALT), creatinine (Cre), and urea nitrogen (Urea), were measured at 0, 3, and 6 h. Serum LPS levels at 6 h were determined by the test kit. And histological changes in the heart, liver and kidney tissues were observed by HE staining. Furthermore, some related small molecules in the heart tissues were detected by MALDI-TOF-MSI.

RESULTS

We found that Shenfu injection can increase the MAP, decrease the serum LPS, LDH and AST levels, and improve the tissue morphology of the heart, liver and kidney in rabbits with LPS-induced septic shock. In addition, Shenfu injection can increase the contents of ATP and taurine while reducing the content of AMP in the heart tissue during septic shock.

CONCLUSIONS

These results indicate that Shenfu injection exerts a protective effect on LPS-induced septic shock in rabbits.

A Novel Role of a Chemotherapeutic Agent in a Rat Model of Endotoxemia: Modulation of the STAT-3 Signaling Pathway

Sepsis caused by lipopolysaccharide (LPS) is a life-threatening disease accompanied by multiple organ failure. This study investigated the curative effects of imatinib (IMA) against hepatic, renal, and pulmonary responses caused by a single administration of LPS (10 mg/kg, i.p.) in rats. Treatment with IMA (15 mg/kg, i.p.) 30 min after LPS antagonized the LPS-induced boost of liver enzymes (ALT, AST), kidney functions (BUN, sCr) as well as the elevated pulmonary vascular permeability and edema. IMA declined tissue contents of NF-κB, STAT-3, P38-MAPK, TNF-α, IL-1β, and iNOS. It also amplified the anti-inflammatory cytokine IL-10 as well as the Bcl-2/Bax ratio, a cardinal indicator of the anti-apoptotic effect. Meanwhile, the rats exhibited marked reduction of the broncho-alveolar lavage fluid (BALF) contents of TNF-α, IL-1β, IFN-γ, and neutrophil count; however, they revealed prominent augmentation of the BALF content IL-10. In conclusion, these findings suggest that IMA is endowed with anti-inflammatory, anti-oxidant, and anti-apoptotic properties and hence may provide a novel agent for the management of sepsis.

Relationship between CaSRs and LPS-injured cardiomyocytes

OBJECTIVE

Calcium-sensing receptors (CaSRs) regulate systemic calcium homeostasis. Intracellular calcium concentration changes are initiating factors of endoplasmic reticulum stress and cell autophagy. Recent research has revealed that CaSRs play an important role in myocardial ischemia/reperfusion injury and other cardiovascular diseases. However, it remains unclear whether CaSRs are involved in lipopolysaccharide (LPS)-induced cardiomyocyte injury.

METHODS

Cultured neonatal rat cardiomyocytes were treated with LPS, with or without pretreatment by a CaSR specific agonist SC-211006 or CaSR specific antagonist SC-207394. The ultrastructure of cardiomyocytes was observed using a transmission electron microscope, and the expression of CaSR, GRP78, LC3B, CytC and Bcl-2 proteins were detected by western blot.

RESULTS

Compared with the control group, LPS increased cardiomyocyte injury and the expression of CaSR, GRP78, LC3B and CytC proteins, but decreased the expression of Bcl-2. Compared with the LPS group, pretreatment with SC-211006 further enhanced cardiomyocyte damage and the expression of CaSR, GRP78, LC3B and CytC, but reduced the expression of Bcl-2. Conversely, pretreatment with SC-207394 decreased cardiomyocyte injury and the protein expression of CaSR, GRP78, LC3B and CytC, but increased the expression of Bcl-2.

CONCLUSION

Our results suggest that CaSRs are involved in LPS-induced rat cardiomyocyte injury via the activation of endoplasmic reticulum stress and autophagy.

Mitochondrial Mechanisms in Septic Cardiomyopathy

Sepsis is the manifestation of the immune and inflammatory response to infection that may ultimately result in multi organ failure. Despite the therapeutic strategies that have been used up to now, sepsis and septic shock remain a leading cause of death in critically ill patients. Myocardial dysfunction is a well-described complication of severe sepsis, also referred to as septic cardiomyopathy, which may progress to right and left ventricular pump failure. Many substances and mechanisms seem to be involved in myocardial dysfunction in sepsis, including toxins, cytokines, nitric oxide, complement activation, apoptosis and energy metabolic derangements. Nevertheless, the precise underlying molecular mechanisms as well as their significance in the pathogenesis of septic cardiomyopathy remain incompletely understood. A well-investigated abnormality in septic cardiomyopathy is mitochondrial dysfunction, which likely contributes to cardiac dysfunction by causing myocardial energy depletion. A number of mechanisms have been proposed to cause mitochondrial dysfunction in septic cardiomyopathy, although it remains controversially discussed whether some mechanisms impair mitochondrial function or serve to restore mitochondrial function. The purpose of this review is to discuss mitochondrial mechanisms that may causally contribute to mitochondrial dysfunction and/or may represent adaptive responses to mitochondrial dysfunction in septic cardiomyopathy.

Ultrastructure of mitochondria and the endoplasmic reticulum in renal tubules of Dahl salt-sensitive rats

Metabolic and functional abnormalities in the kidney precede or coincide with the initiation of overt hypertension in the Dahl salt-sensitive (SS) rat. However, renal histological injury in SS rats is mild before the development of overt hypertension. We performed electron microscopy analysis in 7-wk-old SS rats and salt-insensitive consomic SS.13(BN) rats and Sprague-Dawley (SD) rats fed a 4% NaCl diet for 7 days. Long mitochondria (>2 μm) accounted for a significantly smaller fraction of mitochondria in medullary thick ascending limbs in SS rats (4% ± 1%) than in SS.13(BN) rats (8% ± 1%, P < 0.05 vs. SS rats) and SD rats (9% ± 1%, P < 0.01 vs. SS rats), consistent with previous findings of mitochondrial functional insufficiency in the medulla of SS rats. Long mitochondria in proximal tubules, however, were more abundant in SS rats than in SS.13(BN) and SD rats. The width of the endoplasmic reticulum, an index of endoplasmic reticulum stress, was significantly greater in medullary thick ascending limbs of SS rats (107 ± 1 nm) than in SS.13(BN) rats (95 ± 2 nm, P < 0.001 vs. SS rats) and SD rats (74 ± 3 nm, P < 0.01 vs. SS or SS.13(BN) rats). The tubules examined were indistinguishable between rat strains under light microscopy. These data indicate that ultrastructural abnormalities occur in the medullary thick ascending limbs of SS rats before the development of histological injury in renal tubules, providing a potential structural basis contributing to the subsequent development of overt hypertension.

Resveratrol attenuates left ventricular remodeling in old rats with COPD induced by cigarette smoke exposure and LPS instillation

The objective of this study was to investigate left cardiac damage and the cardioprotective effects of resveratrol in old rats with COPD. Rats 22 months old were divided into three groups: control (CTL), smoking and lipopolysaccharides (SM/LPS), and SM/LPS plus resveratrol (SM/LPS-Res). Cardiac function, pathology, oxidative stress, and apoptosis index were measured. Expression of myocardial SIRT1 was studied by real-time quantitative polymerase chain reaction (PCR) and Western blot detection. The heart weight-body weight ratio (LVW/BW) increased in the SM/LPS group compared with the CTL group. Both the LVW/BW and the area of fibrosis in the SM/LPS-Res group decreased compared with those in the SM/LPS group. 8-OHdG expression increased in cardiac tissue of rats in the SM/LPS group, which could be inhibited by resveratrol. Resveratrol significantly increased the activity of superoxide dismutase (SOD) and reduced the cardiac malonyldialdehyde (MDA) level in the SM/LPS-Res group. There was a significant decrease in the extent of cardiomyocyte apoptosis in the SM/LPS-Res group compared with the SM/LPS group. SIRT1 mRNA increased in the SM/LPS-Res group compared with the SM/LPS group. In conclusion, resveratrol attenuated cardiac oxidative damage and left ventricular remodeling and enhanced the decreased expression of SIRT1 in hearts of old rats with emphysema and thus might be a therapeutic modality for cardiac injury complicated in chronic obstructive pulmonary disease (COPD).

The NO/ONOO-cycle as the central cause of heart failure

The NO/ONOO-cycle is a primarily local, biochemical vicious cycle mechanism, centered on elevated peroxynitrite and oxidative stress, but also involving 10 additional elements: NF-κB, inflammatory cytokines, iNOS, nitric oxide (NO), superoxide, mitochondrial dysfunction (lowered energy charge, ATP), NMDA activity, intracellular Ca(2+), TRP receptors and tetrahydrobiopterin depletion. All 12 of these elements have causal roles in heart failure (HF) and each is linked through a total of 87 studies to specific correlates of HF. Two apparent causal factors of HF, RhoA and endothelin-1, each act as tissue-limited cycle elements. Nineteen stressors that initiate cases of HF, each act to raise multiple cycle elements, potentially initiating the cycle in this way. Different types of HF, left vs. right ventricular HF, with or without arrhythmia, etc., may differ from one another in the regions of the myocardium most impacted by the cycle. None of the elements of the cycle or the mechanisms linking them are original, but they collectively produce the robust nature of the NO/ONOO-cycle which creates a major challenge for treatment of HF or other proposed NO/ONOO-cycle diseases. Elevated peroxynitrite/NO ratio and consequent oxidative stress are essential to both HF and the NO/ONOO-cycle.

Enoyl coenzyme a hydratase domain-containing 2, a potential novel regulator of myocardial ischemia injury

Background

We reported previously that Brown Norway (BN) rats are more resistant to myocardial ischemia/reperfusion (I/R) injury than are Dahl S (SS) rats. To identify the unique genes differentially expressed in the hearts of these rats, we used DNA microarray analysis and observed that enoyl coenzyme A hydratase–containing domain 2 (ECHDC2) is highly expressed (≈18‐fold) in the SS hearts compared with the BN hearts.

Methods and Results

RT‐PCR, Western blot, and immunohistochemistry analyses verified that ECHDC2 was highly expressed in SS hearts compared with the BN hearts. ECHDC2 gene locates at chromosome 5 of rat and is expressed in mitochondria of the heart, mainly in cardiomyocytes but not in cardiofibroblasts. Overexpression of ECHDC2 in cells increased susceptibility to I/R injury while knockdown of ECHDC2 enhanced resistance to I/R injury. Furthermore, we observed that left anterior descending coronary artery ligation–induced myocardial infarction was more severe in the SS hearts than in the BN hearts or SSBN5 hearts, which was built on SS rats but had the substitution of chromosome 5 from BN rats. We also demonstrated that ECHDC2 did not alter mitochondrial O₂ consumption, metabolic intermediates and ATP production. By gas chromatography–mass spectrometry, we found that ECHDC2 overexpression increased the levels of the cellular branched chain amino acids leucine and valine.

Conclusion

ECHDC2, a mitochondrial protein, may be involved in regulating cell death and myocardial injury. Its deficiency in BN rats contributes to their increased resistance to myocardial I/R compared with SS rats. ECHDC2 increases branched chain amino acid metabolism and appears to be a novel regulator linking cell metabolism with cardiovascular disease.