Stimulation of mitochondrial biogenesis and autophagy by lipopolysaccharide in the neonatal rat cardiomyocyte protects against programmed cell death

Pathobiology of myocardial and cardiomyocyte injury in ischemic heart disease: Perspective from seventy years of cell injury research

This review presents a perspective on the pathobiology of acute myocardial infarction, a major manifestation of ischemic heart disease, and related mechanisms of ischemic and toxic cardiomyocyte injury, based on advances and insights that have accrued over the last seventy years, including my sixty years of involvement in the field as a physician-scientist-pathologist. This analysis is based on integration of my research within the broader context of research in the field. A particular focus has been on direct measurements in cardiomyocytes of electrolyte content by electron probe X-ray microanalysis (EPXMA) and Ca2+ fluxes by fura-2 microspectrofluorometry. These studies established that increased intracellular Ca2+ develops at a transitional stage in the progression of cardiomyocyte injury in association with ATP depletion, other electrolyte alterations, altered cell volume regulation, and altered membrane phospholipid composition. Subsequent increase in total calcium with mitochondrial calcium accumulation can occur. These alterations are characteristic of oncosis, which is an initial pre-lethal state of cell injury with cell swelling due to cell membrane dysfunction in ATP depleted cells; oncosis rapidly progresses to necrosis/necroptosis with physical disruption of the cell membrane, unless the adverse stimulus is rapidly reversed. The observed sequential changes fit a three-stage model of membrane injury leading to irreversible cell injury. The data establish oncosis as the primary mode of cardiomyocyte injury in evolving myocardial infarcts. Oncosis also has been documented to be the typical form of non-ischemic cell injury due to toxins. Cardiomyocytes with less energy impairment have the capability of undergoing apoptosis and autophagic death as well as oncosis, as is seen in pathological remodeling in chronic heart failure. Work is ongoing to apply the insights from experimental studies to better understand and ameliorate myocardial ischemia and reperfusion injury in patients. The perspective and insights in this review are derived from basic principles of pathology, an integrative discipline focused on mechanisms of disease affecting the cell, the organizing unit of living organisms.

Interplay of Reactive Oxygen Species (ROS) and Epigenetic Remodelling in Cardiovascular Diseases Pathogenesis: A Contemporary Perspective

Cardiovascular diseases (CVDs) continue to be the leading cause of mortality worldwide, necessitating the development of novel therapies. Despite therapeutic advancements, the underlying mechanisms remain elusive. Reactive oxygen species (ROS) show detrimental effects at high concentrations but act as essential signalling molecules at physiological levels, playing a critical role in the pathophysiology of CVD. However, the link between pathologically elevated ROS and CVDs pathogenesis remains poorly understood. Recent research has highlighted the remodelling of the epigenetic landscape as a crucial factor in CVD pathologies. Epigenetic changes encompass alterations in DNA methylation, post-translational histone modifications, adenosine triphosphate (ATP)-dependent chromatin modifications, and noncoding RNA transcripts. Unravelling the intricate link between ROS and epigenetic changes in CVD is challenging due to the complexity of epigenetic signals in gene regulation. This review aims to provide insights into the role of ROS in modulating the epigenetic landscape within the cardiovascular system. Understanding these interactions may offer novel therapeutic strategies for managing CVD by targeting ROS-induced epigenetic changes. It has been widely accepted that epigenetic modifications are established during development and remain fixed once the lineage-specific gene expression pattern is achieved. However, emerging evidence has unveiled its remarkable dynamism. Consequently, it is now increasingly recognized that epigenetic modifications may serve as a crucial link between ROS and the underlying mechanisms implicated in CVD.

Isoquercitrin alleviates OGD/R-induced oxidative stress and impaired mitochondrial biogenesis in SH-SY5Y cells via the NRF1/TFAM pathway

Isoquercitrin (ISO) is a traditional Chinese medicine extract, that has been found to possess potent neuroprotective properties. However, its precise role in the context of ischemic stroke (IS) remains to be fully elucidated. We constructed an in vitro model of IS induced by OGD/R in SH-SY5Y cells. Cell viability, the levels of oxidative stress-related indicators (8-OHDG, MDA, SOD, GSH, and GSH-Px), ROS, and mitochondrial membrane potential were measured by using detection kits. The protein levels of GPX1, SOD, Cytc were measured. The mRNA levels of mitochondrial biogenesis-related indicators (Cytb, CO1, ND2, ND5, and ND6), and mtDNA copy number were measured by RT-qPCR. ATP levels were measured. Molecular docking between ISO and NRF1, and Co-IP assay for NRF1 and TFAM interaction were performed. Expression of NRF1 and TFAM was evaluated. ISO treatment reversed the detrimental effects of OGD/R on cell viability, attenuated the elevation of oxidative stress markers, restored antioxidant levels, and alleviated the impairment of mitochondrial biogenesis in SH-SY5Y cells. ISO interacted with NRF1 and increased its expression along with TFAM. Silencing NRF1 reversed the protective effects of ISO, suggesting its involvement in mediating the neuroprotective effects of ISO. ISO alleviates oxidative stress and mitochondrial biogenesis damage induced by OGD/R in SH-SY5Y cells by upregulating the NRF1/TFAM pathway.

The role of uterus mitochondrial function in high-fat diet-related adverse pregnancy outcomes and protection by resveratrol

This study elucidates the mechanism of obesity-related adverse pregnancy outcomes and further investigates the effect of resveratrol on reproductive performance in a short- or long-term HFD-induced obese mouse model. Results show that maternal weight had a significant positive correlation with litter mortality in mice. A long-term HFD increased body weight and litter mortality with decreased expression of uterine cytochrome oxidase 4 (COX4), which was recovered by resveratrol in mice. Moreover, HFD decreased the expression of peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), nuclear respiratory factors-1 (Nrf-1), and phosphorylated adenosine 5'-monophosphate (AMP)-activated protein kinase (p-AMPK) and increased the expression of phosphorylated extracellular regulated protein kinases (p-ERK) in the uterus. Resveratrol, a polyphenol that can directly bind to the ERK protein, suppressed the phosphorylation of ERK, increased the expression of p-AMPK, PGC-1α and Nrf-1, and decreased litter mortality in mice.

Activation of G-protein-coupled receptor 39 reduces neuropathic pain in a rat model

Activated G-protein-coupled receptor 39 (GPR39) has been shown to attenuate inflammation by interacting with sirtuin 1 (SIRT1) and peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α). However, whether GPR39 attenuates neuropathic pain remains unclear. In this study, we established a Sprague-Dawley rat model of spared nerve injury-induced neuropathic pain and found that GPR39 expression was significantly decreased in neurons and microglia in the spinal dorsal horn compared with sham-operated rats. Intrathecal injection of TC-G 1008, a specific agonist of GPR39, significantly alleviated mechanical allodynia in the rats with spared nerve injury, improved spinal cord mitochondrial biogenesis, and alleviated neuroinflammation. These changes were abolished by GPR39 small interfering RNA (siRNA), Ex-527 (SIRT1 inhibitor), and PGC-1α siRNA. Taken together, these findings show that GPR39 activation ameliorates mechanical allodynia by activating the SIRT1/PGC-1α pathway in rats with spared nerve injury.

Golgi Protein 73 Promotes LPS-Induced Cardiac Dysfunction via Mediating Myocardial Apoptosis and Autophagy

ABSTRACT

Sepsis-induced cardiac dysfunction represents a major cause of high mortality in intensive care units with limited therapeutic options. Golgi protein 73 (GP73) has been implicated in various diseases. However, the role of GP73 in lipopolysaccharide (LPS)-induced cardiac dysfunction is unclear. In this study, we established a sepsis-induced cardiac dysfunction model by LPS administration in wild-type and GP73 knockout ( GP73-/- ) mice. We found that GP73 was increased in LPS-treated mouse hearts and LPS-cultured neonatal rat cardiomyocytes (NRCMs). Knockout of GP73 alleviated myocardial injury and improved cardiac dysfunction. Moreover, depletion of GP73 in NRCMs relieved LPS-induced cardiomyocyte apoptosis and activated myocardial autophagy. Therefore, GP73 is a negative regulator in LPS-induced cardiac dysfunction by promoting cardiomyocyte apoptosis and inhibiting cardiomyocyte autophagy.

Premature senescence and cardiovascular disease following cancer treatments: mechanistic insights

Cardiovascular disease (CVD) is a leading cause of morbidity and mortality, especially among the aging population. The "response-to-injury" model proposed by Dr. Russell Ross in 1999 emphasizes inflammation as a critical factor in atherosclerosis development, with atherosclerotic plaques forming due to endothelial cell (EC) injury, followed by myeloid cell adhesion and invasion into the blood vessel walls. Recent evidence indicates that cancer and its treatments can lead to long-term complications, including CVD. Cellular senescence, a hallmark of aging, is implicated in CVD pathogenesis, particularly in cancer survivors. However, the precise mechanisms linking premature senescence to CVD in cancer survivors remain poorly understood. This article aims to provide mechanistic insights into this association and propose future directions to better comprehend this complex interplay.

NUCLEOLIN PROMOTES AUTOPHAGY THROUGH PGC-1Α IN LPS-INDUCED MYOCARDIAL INJURY

ABSTRACT

As a multifunctional protein, nucleolin can participate in a variety of cellular processes. Nucleolin also has multiple protective effects on heart disease. Previous studies have shown that nucleolin could not only resist oxidative stress damage and inflammatory damage, but also regulate autophagy to play a protective role in cardiac ischemia. However, the specific mechanism has not been fully elucidated in LPS-induced myocardial injury. Therefore, the aim of this study is to explore the underlying mechanism by which nucleolin regulates autophagy to protect against LPS-induced myocardial injury in vivo and in vitro . In our study, we found that nucleolin could bind to PGC-1α, and we predicted that this interaction could promote autophagy and played a role in inhibiting cardiomyocyte apoptosis. Downregulation of nucleolin in H9C2 cells resulted in decreased autophagy and increased cell apoptosis during LPS-induced myocardial injury, while upregulation of PGC-1α had the opposite protective effect. Upregulation of nucleolin expression in cardiomyocytes could increase the level of autophagy during LPS-induced myocardial injury. In contrast, interference with PGC-1α expression resulted in a decrease in the protective effect of nucleolin, leading to reduced autophagy and thus increasing apoptosis. By using tandem fluorescent-tagged LC3 autophagic flux detection system, we observed autophagic flux and determined that PGC-1α interference could block autophagic lysosomal progression. We further tested our hypothesis in the nucleolin cardiac-specific knockout mice. Finally, we also found that inhibition of autophagy can reduce mitochondrial biogenesis as well as increase apoptosis, which demonstrated the importance of autophagy. Therefore, we can speculate that nucleolin can protect LPS-induced myocardial injury by regulating autophagy, and this protective effect may be mediated by the interaction with PGC-1α, which can positively regulate the ULK1, an autophagy-related protein. Our study provides a new clue for the cardioprotective effect of nucleolin, and may provide new evidence for the treatment of LPS-induced myocardial injury through the regulation of autophagy.

Mitochondrial epigenetics in aging and cardiovascular diseases

Mitochondria are cellular organelles which generate adenosine triphosphate (ATP) molecules for the maintenance of cellular energy through the oxidative phosphorylation. They also regulate a variety of cellular processes including apoptosis and metabolism. Of interest, the inner part of mitochondria-the mitochondrial matrix-contains a circular molecule of DNA (mtDNA) characterised by its own transcriptional machinery. As with genomic DNA, mtDNA may also undergo nucleotide mutations that have been shown to be responsible for mitochondrial dysfunction. During physiological aging, the mitochondrial membrane potential declines and associates with enhanced mitophagy to avoid the accumulation of damaged organelles. Moreover, if the dysfunctional mitochondria are not properly cleared, this could lead to cellular dysfunction and subsequent development of several comorbidities such as cardiovascular diseases (CVDs), diabetes, respiratory and cardiovascular diseases as well as inflammatory disorders and psychiatric diseases. As reported for genomic DNA, mtDNA is also amenable to chemical modifications, namely DNA methylation. Changes in mtDNA methylation have shown to be associated with altered transcriptional programs and mitochondrial dysfunction during aging. In addition, other epigenetic signals have been observed in mitochondria, in particular the interaction between mtDNA methylation and non-coding RNAs. Mitoepigenetic modifications are also involved in the pathogenesis of CVDs where oxygen chain disruption, mitochondrial fission, and ROS formation alter cardiac energy metabolism leading to hypertrophy, hypertension, heart failure and ischemia/reperfusion injury. In the present review, we summarize current evidence on the growing importance of epigenetic changes as modulator of mitochondrial function in aging. A better understanding of the mitochondrial epigenetic landscape may pave the way for personalized therapies to prevent age-related diseases.

Cardiac-specific overexpression of catalase attenuates lipopolysaccharide-induced cardiac anomalies through reconciliation of autophagy and ferroptosis

Lipopolysaccharide (LPS) from Gram-negative bacteria is a major contributor to cardiovascular failure, but the signaling mechanisms underlying its stress response are not fully understood. This study aimed to investigate the effect of the antioxidant enzyme catalase on LPS-induced cardiac abnormalities and the mechanisms involved, with particular focus on the interplay between autophagy, ferroptosis, and apoptosis. Cardiac-specific catalase (CAT) overexpression and wild-type (WT) mice were stimulated with LPS (6 mg/kg, intravenous injection), and cardiac morphology and function were evaluated. Oxidative stress, ferroptosis, apoptosis, and mitochondrial status were monitored, and survival curves were plotted based on the results of LPS stimulation. The results showed that, compared with WT mice, mice overexpressing catalase had a higher survival rate under LPS stimulation. Ultrasound echocardiography, cardiomyocyte characteristics, and Masson's trichrome staining showed that LPS inhibited cardiac function and caused cardiac fibrosis, while catalase alleviated these adverse effects. LPS increased apoptosis (TUNEL, caspase-3 activation, cleaved caspase-3), increased O₂^·- production, induced inflammation (TNF-α), autophagy, iron toxicity, and carbonyl damage, and significantly damaged mitochondria (mitochondrial membrane potential, mitochondrial proteins, and ultrastructure). These effects were significantly alleviated by catalase. Interestingly, the antioxidant N-acetylcysteine, autophagy inhibitor 3-methyladenine, and ferroptosis inhibitor lipostatin-1 all eliminated the LPS-induced contraction dysfunction and ferroptosis (using lipid peroxidation). Induction of ferroptosis could eliminate the cardioprotective effect of NAC. In conclusion, catalase rescues LPS-induced cardiac dysfunction by regulating oxidative stress, autophagy, ferroptosis, apoptosis, and mitochondrial damage in cardiomyocytes.

Anti-inflammatory activity of carvacrol protects the heart from lipopolysaccharide-induced cardiac dysfunction by inhibiting pyroptosis via NLRP3/Caspase1/Gasdermin D signaling axis

AIMS

Lipopolysaccharide (LPS) is a well-known agent to induce septic conditions. Sepsis-induced cardiomyopathy has an overwhelming death rate. Carvacrol (CVL), a monoterpene phenol, has anti-inflammatory and antioxidant properties. The research aimed to investigate the effect of CVL on LPS-induced dysfunction in the heart. In this study, we evaluated the effect of CVL in LPS-stimulated H9c2 cardiomyoblast cells and Balb/c mice.

MAIN METHODS

LPS was used to induce septic conditions in H9c2 cardiomyoblast cells in vitro and in Balb/C mice. A survival study was conducted to assess the survival rate of mice after LPS and/or CVL treatment.

KEY FINDINGS

In vitro studies indicated that CVL inhibits reactive oxygen species (ROS) generation and abates pyroptosis mediated by NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome in H9c2 cells. In mice, CVL intervention improved the survival rate in septic conditions. The CVL administration markedly improved the echocardiographic parameters and alleviated the LPS-induced reduction in the ejection fraction (%) and fraction shortening (%). The CVL intervention restored the myocardial antioxidants and histopathological alterations and decreased the pro-inflammatory cytokine contents in the heart. Further findings disclosed that CVL reduced the protein levels of NLRP3, apoptosis-associated speck-like protein (ASC), caspase 1, interleukin (IL)-18, IL-1β, and the pyroptosis-indicative protein, gasdermin-D (GSDMD) in the heart. The autophagy-indicative proteins, beclin 1, and p62, in the heart were also restored in the CVL-treated group.

SIGNIFICANCE

Altogether, our findings demonstrated that CVL has a beneficial effect and can be a potential molecule against sepsis-induced myocardial dysfunction.

Cardiomyocyte-specific disruption of soluble epoxide hydrolase limits inflammation to preserve cardiac function

Endotoxemia elicits a multiorgan inflammatory response that results in cardiac dysfunction and often leads to death. Inflammation-induced metabolism of endogenous N-3 and N-6 polyunsaturated fatty acids generates numerous lipid mediators, such as epoxy fatty acids (EpFAs), which protect the heart. However, EpFAs are hydrolyzed by soluble epoxide hydrolase (sEH), which attenuates their cardioprotective actions. Global genetic disruption of sEH preserves EpFA levels and attenuates cardiac dysfunction in mice following acute lipopolysaccharide (LPS)-induced inflammatory injury. In leukocytes, EpFAs modulate the innate immune system through the NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome. However, the mechanisms by which both EpFAs and sEH inhibition exert their protective effects in the cardiomyocyte are still elusive. This study investigated whether cardiomyocyte-specific sEH disruption attenuates inflammation and cardiac dysfunction in acute LPS inflammatory injury via modulation of the NLRP3 inflammasome. We use tamoxifen-inducible CreER recombinase technology to target sEH genetic disruption to the cardiomyocyte. Primary cardiomyocyte studies provide mechanistic insight into inflammasome signaling. For the first time, we demonstrate that cardiomyocyte-specific sEH disruption preserves cardiac function and attenuates inflammatory responses by limiting local cardiac inflammation and activation of the systemic immune response. Mechanistically, inhibition of cardiomyocyte-specific sEH activity or exogenous EpFA treatment do not prevent upregulation of NLRP3 inflammasome machinery in neonatal rat cardiomyocytes. Rather, they limit downstream activation of the pathway leading to release of fewer chemoattractant factors and recruitment of immune cells to the heart. These data emphasize that cardiomyocyte sEH is vital for mediating detrimental systemic inflammation.NEW & NOTEWORTHY The cardioprotective effects of genetic disruption and pharmacological inhibition of sEH have been demonstrated in a variety of cardiac disease models, including acute LPS inflammatory injury. For the first time, it has been demonstrated that sEH genetic disruption limited to the cardiomyocyte profoundly preserves cardiac function and limits local and systemic inflammation following acute LPS exposure. Hence, cardiomyocytes serve a critical role in the innate immune response that can be modulated to protect the heart.

NF-κB p65 Attenuates Cardiomyocyte PGC-1α Expression in Hypoxia

Hypoxia exerts broad effects on cardiomyocyte function and viability, ranging from altered metabolism and mitochondrial physiology to apoptotic or necrotic cell death. The transcriptional coactivator peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) is a key regulator of cardiomyocyte metabolism and mitochondrial function and is down-regulated in hypoxia; however, the underlying mechanism is incompletely resolved. Using primary rat cardiomyocytes coupled with electrophoretic mobility shift and luciferase assays, we report that hypoxia impaired mitochondrial energetics and resulted in an increase in nuclear localization of the Nuclear Factor-κB (NF-κB) p65 subunit, and the association of p65 with the PGC-1α proximal promoter. Tumor necrosis factor α (TNFα), an activator of NF-κB signaling, similarly reduced PGC-1α expression and p65 binding to the PGC-1α promoter in a dose-dependent manner, and TNFα-mediated down-regulation of PGC-1α expression could be reversed by the NF-κB inhibitor parthenolide. RNA-seq analysis revealed that cardiomyocytes isolated from p65 knockout mice exhibited alterations in genes associated with chromatin remodeling. Decreased PGC-1α promoter transactivation by p65 could be partially reversed by the histone deacetylase inhibitor trichostatin A. These results implicate NF-κB signaling, and specifically p65, as a potent inhibitor of PGC-1α expression in cardiac myocyte hypoxia.

Impaired autophagy aggravates oxidative stress in mammary gland of dairy cows with clinical ketosis

When ketosis occurs, supraphysiological levels of free fatty acids (FFA) can cause oxidative injury to the mammary gland and autophagy can regulate the cellular oxidative status. The aim of this study was to investigate the autophagy status of mammary tissue and its associations with oxidative stress in healthy and clinically ketotic dairy cows. Mammary tissue and blood samples were collected from healthy cows [n = 15, β-hydroxybutyrate (BHB) <0.6 mM] and clinically ketotic cows (n = 15, BHB >3.0 mM) at 3 to 15 (average = 7) days in milk. For in vitro study, bovine mammary epithelial cells (BMEC) isolated from healthy cows were treated with 0, 0.3, 0.6, or 1.2 mM FFA for 24 h. Furthermore, BMEC were pretreated with 100 nM rapamycin, an autophagy activator, for 4 h or 50 mM 3-methyladenine (3-MA), an autophagy inhibitor, for 1 h, followed by treatment with or without FFA (1.2 mM) for another 24 h. Oxidation indicators and autophagy-related protein abundance were measured. Compared with healthy cows, serum concentrations of FFA, BHB, and malondialdehyde were greater in clinically ketotic cows, but milk production (kg/d), milk protein (kg/d), activities of superoxide dismutase, catalase, and glutathione peroxidase were lower. Abundances of mRNA and protein of autophagy-related gene 5 (ATG5) and 7 (ATG7) were lower, but sequestosome-1 (SQSTM1, also called p62) greater in mammary tissue of clinically ketotic cows. The mRNA abundance of microtubule-associated protein 1 light chain 3 (MAP1LC3, also called LC3) and protein abundance of LC3-II were lower in mammary tissue of clinically ketotic cows. In vitro, exogenous FFA increased the content of malondialdehyde and reactive oxygen species, but decreased the activities of superoxide dismutase, catalase, and plasma glutathione peroxidase. Compared with the 0 mM FFA group, abundance of ATG5, ATG7, LC3-II was greater, but p62 was lower in the 0.6 mM FFA-treated cells. Similarly, abundance of ATG5, ATG7, and LC3-II was lower, but p62 greater in the 1.2 mM FFA-treated cells relative to 0 mM FFA group. Culture with rapamycin alleviated oxidative stress induced by 1.2 mM FFA, whereas 3-MA aggravated it. Overall, results indicated that a low concentration (0.6 mM) of FFA can induce oxidative stress and activate autophagy in BMEC. At higher concentrations of FFA (1.2 mM), autophagy is impaired and oxidative stress is aggravated. Autophagy is a mechanism for BMEC to counteract FFA-induced stress. As such, it could serve as a potential target for further development of novel strategies against oxidative stress.

Short-term Obesity Worsens Heart Inflammation and Disrupts Mitochondrial Biogenesis and Function in an Experimental Model of Endotoxemia

Cardiomyopathy is a well-known complication of sepsis that may deteriorate when accompanied by obesity. To test this hypothesis we fed C57black/6 male mice for 6 week with a high fat diet (60% energy) and submitted them to endotoxemic shock using E. coli LPS (10 mg/kg). Inflammatory markers (cytokines and adhesion molecules) were determined in plasma and heart tissue, as well as heart mitochondrial biogenesis and function. Obesity markedly shortened the survival rate of mouse after LPS injection and induced a persistent systemic inflammation since TNFα, IL-1β, IL-6 and resistin plasma levels were higher 24 h after LPS injection. Heart tissue inflammation was significantly higher in obese mice, as detected by elevated mRNA expression of pro-inflammatory cytokines (IL-1β, IL-6 and TNFα). Obese animals presented reduced maximum respiratory rate after LPS injection, however fatty acid oxidation increased in both groups. LPS decreased mitochondrial DNA content and mitochondria biogenesis factors, such as PGC1α and PGC1β, in both groups, while NRF1 expression was significantly stimulated in obese mice hearts. Mitochondrial fusion/fission balance was only altered by obesity, with no influence of endotoxemia. Obesity accelerated endotoxemia death rate due to higher systemic inflammation and decreased heart mitochondrial respiratory capacity.

Hippo Pathway Effector Tead1 Induces Cardiac Fibroblast to Cardiomyocyte Reprogramming

Background The conversion of fibroblasts into induced cardiomyocytes may regenerate myocardial tissue from cardiac scar through in situ cell transdifferentiation. The efficiency transdifferentiation is low, especially for human cells. We explored the leveraging of Hippo pathway intermediates to enhance induced cardiomyocyte generation. Methods and Results We screened Hippo effectors Yap (yes-associated protein), Taz (transcriptional activator binding domain), and Tead1 (TEA domain transcription factor 1; Td) for their reprogramming efficacy with cardio-differentiating factors Gata4, Mef2C, and Tbx5 (GMT). Td induced nearly 3-fold increased expression of cardiomyocyte marker cTnT (cardiac troponin T) by mouse embryonic and adult rat fibroblasts versus GMT administration alone (P<0.0001), while Yap and Taz failed to enhance cTnT expression. Serial substitution demonstrated that Td replacement of TBX5 induced the greatest cTnT expression enhancement and sarcomere organization in rat fibroblasts treated with all GMT substitutions (GMTd versus GMT: 17±1.2% versus 5.4±0.3%, P<0.0001). Cell contractility (beating) was seen in 6% of GMTd-treated cells by 4 weeks after treatment, whereas no beating GMT-treated cells were observed. Human cardiac fibroblasts likewise demonstrated increased cTnT expression with GMTd versus GMT treatment (7.5±0.3% versus 3.0±0.3%, P<0.01). Mechanistically, GMTd administration increased expression of the trimethylated lysine 4 of histone 3 (H3K4me3) mark at the promoter regions of cardio-differentiation genes and mitochondrial biogenesis regulator genes in rat and human fibroblast, compared with GMT. Conclusions These data suggest that the Hippo pathway intermediate Tead1 is an important regulator of cardiac reprogramming that increases the efficiency of maturate induced cardiomyocytes generation and may be a vital component of human cardiodifferentiation strategies.

Nesfatin-1 alleviates high glucose/high lipid-induced injury of trophoblast cells during gestational diabetes mellitus

Gestational diabetes mellitus (GDM) is a common disease in pregnant women, imposing risks on both mother and fetus. Dysregulated nesfatin-1 has been observed in women with GDM, but the specific role of nesfatin-1 underlying the pathological process of GDM is unclear. The main objective of this study is to investigate the role and the molecular mechanism of nesfatin-1 in GDM. HTR-8/SVneo cells were treated with high glucose (HG)/high lipid (HL) to mimic the injured trophoblast of GDM in vitro. Cell viability, cytotoxicity and apoptosis were measured using CCK-8, LDH and TUNEL assays, respectively. The levels of inflammatory cytokines and antioxidant factors were detected using their commercial kits. ATP level and cytochrome c were determined with corresponding detecting kits. Quantitative real-time PCR and Western blot were performed to detect the expression of corresponding genes. The results showed that nesfatin-1 was downregulated upon HG/HL stimulation. Nesfatin-1 treatment greatly alleviated HG/HL-induced cell viability loss, cytotoxicity, inflammatory response, oxidative stress, and apoptosis in HTR-8/SVneo cells. In addition, nesfatin-1 promoted ATP generation, reduced the leakage of cytochrome c from mitochondria to cytoplasm, and upregulated mitochondrial transcription factor A (TFAM) and nuclear respiratory factor 1 (NRF1), alleviating mitochondrial dysfunction. Furthermore, nesfatin-1 inhibited p38 MAPK signaling. p79350, an agonist of p38 MAPK signaling, remarkably hindered the protective role of nesfatin-1 in HG/HL-induced HTR-8/SVneo cells. In conclusion, nesfatin-1 exerted a protective effect on GDM model in vitro, by regulating p38 MAPK signaling pathway, providing novel insights of treating GDM.

Resveratrol sustains intestinal barrier integrity, improves antioxidant capacity, and alleviates inflammation in the jejunum of ducks exposed to acute heat stress

Resveratrol, a natural antioxidant, anti-inflammatory plant extract, was found to have a protective effect in poultry subjected to heat stress. In this study, we strove to characterize resveratrol on intestinal of duck exposed to acute heat stress and investigate the underlying mechanism. A total of 120 Shan-ma ducks (60 days old) were randomly divided into 2 groups. The control group was fed a basal diet, and the resveratrol group was fed a basal diet supplemented with 400 mg/kg resveratrol. Animals in 2 groups were kept at a temperature of 24°C ± 2°C for 15 d. Then, animals of both groups were placed in an artificial climate room at 39°C. Twelve ducks of each group were sacrificed for sampling at 0, 30, and 60 min, respectively. Results indicated that resveratrol increased the ratio of villus height to crypt depth, increased the number of goblet cells, and reduced the histopathological damage of jejunum caused by acute heat stress. Furthermore, the gene expression of heat shock proteins (HSP60, HSP70, and HSP90) and tight junction proteins (CLDN1 and OCLN) was significantly increased in the resveratrol group compared to that in the control groups. Simultaneously, resveratrol significantly activated the SIRT1-NRF1/NRF2 signaling pathways, improved ATP level of jejunum, and increased SOD and CAT antioxidant enzymes activities. In addition, we found that the NF-κB/NLRP3 inflammasome signaling pathways were repressed under acute heat stress. Meanwhile, supplement resveratrol further inhibited the NLRP3 inflammasome pathway, decreased protein level of NLRP3 and caspase1 p20, reduced the secretion of IL-1β. Taken together, our results indicate that resveratrol against the oxidative damage and inflammation injury in duck jejunum induced by heat stress via active SIRT1 signaling pathways.

Energetic dysfunction in sepsis: a narrative review

Background

Growing evidence associates organ dysfunction(s) with impaired metabolism in sepsis. Recent research has increased our understanding of the role of substrate utilization and mitochondrial dysfunction in the pathophysiology of sepsis-related organ dysfunction. The purpose of this review is to present this evidence as a coherent whole and to highlight future research directions.

Main text

Sepsis is characterized by systemic and organ-specific changes in metabolism. Alterations of oxygen consumption, increased levels of circulating substrates, impaired glucose and lipid oxidation, and mitochondrial dysfunction are all associated with organ dysfunction and poor outcomes in both animal models and patients. The pathophysiological relevance of bioenergetics and metabolism in the specific examples of sepsis-related immunodeficiency, cerebral dysfunction, cardiomyopathy, acute kidney injury and diaphragmatic failure is also described.

Conclusions

Recent understandings in substrate utilization and mitochondrial dysfunction may pave the way for new diagnostic and therapeutic approaches. These findings could help physicians to identify distinct subgroups of sepsis and to develop personalized treatment strategies. Implications for their use as bioenergetic targets to identify metabolism- and mitochondria-targeted treatments need to be evaluated in future studies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13613-021-00893-7.

Sepsis-Induced Myocardial Dysfunction (SIMD): the Pathophysiological Mechanisms and Therapeutic Strategies Targeting Mitochondria

Sepsis is a lethal syndrome with multiple organ failure caused by an inappropriate host response to infection. Cardiac dysfunction is one of the important complications of sepsis, termed sepsis-induced myocardial dysfunction (SIMD), which is characterized by systolic and diastolic dysfunction of both sides of the heart. Mechanisms that contribute to SIMD include an excessive inflammatory response, altered circulatory, microvascular status, nitric oxide (NO) synthesis impairment, endothelial dysfunction, disorders of calcium regulation, cardiac autophagy anomaly, autonomic nervous system dysregulation, metabolic reprogramming, and mitochondrial dysfunction. The role of mitochondrial dysfunction, which is characterized by structural abnormalities, increased oxidative stress, abnormal opening of the mitochondrial permeability transition pore (mPTP), mitochondrial uncoupling, and disordered quality control systems, has been gaining increasing attention as a central player in the pathophysiology of SIMD. The disruption of homeostasis within the organism induced by mitochondrial dysfunction may also be an important aspect of SIMD development. In addition, an emerging therapy strategy targeting mitochondria, namely, metabolic resuscitation, seems promising. The current review briefly introduces the mechanism of SIMD, highlights how mitochondrial dysfunction contributes to SIMD, and discusses the role of metabolic resuscitation in the treatment of SIMD.

Selective inhibition of PKCβ2 improves Caveolin-3/eNOS signaling and attenuates lipopolysaccharide-induced injury by inhibiting autophagy in H9C2 cardiomyocytes

Lipopolysaccharide (LPS)-induced autophagy is involved in sepsis-associated myocardial injury with increased PKCβ2 activation. We previously found hyperglycemia-induced PKCβ2 activation impaired the expression of caveolin-3 (Cav-3), the dominant isoform to form cardiomyocytes caveolae which modulate eNOS signaling to confer cardioprotection in diabetes. However, little is known about the roles of PKCβ2 in autophagy and Cav-3/eNOS signaling in cardiomyocytes during LPS exposure. We hypothesize LPS-induced PKCβ2 activation promotes autophagy and impairs Cav-3/eNOS signaling in LPS-treated cardiomyocytes. H9C2 cardiomyocytes were treated with LPS (10 µg/mL) in the presence or absence of PKCβ2 inhibitor CGP53353 (CGP, 1 µM) or autophagy inhibitor 3-methyladenine (3-MA, 10 µM). LPS stimulation induced cytotoxicity overtime in H9C2 cardiomyocytes, accompanied with excessive PKCβ2 activation. Selective inhibition of PKCβ2 with CGP significantly reduced LPS-induced cytotoxicity and autophagy (measured by LC-3II, Beclin-1, p62 and autophagic flux). In addition, CGP significantly attenuated LPS-induced oxidative injury, and improved Cav-3 expression and eNOS activation, similar effects were shown by the treatment of autophagy inhibitor 3-MA. LPS-induced myocardial injury is associated with excessive PKCβ2 activation, which contributes to elevated autophagy and impaired Cav-3/eNOS signaling. Selective inhibition of PKCβ2 improves Cav-3/eNOS signaling and attenuates LPS-induced injury through inhibiting autophagy in H9C2 cardiomyocytes.

Autophagy Alters Bladder Angiogenesis and Improves Bladder Hyperactivity in the Pathogenesis of Ketamine-Induced Cystitis in a Rat Model

Simple Summary

Long-term ketamine abuse may increase urinary frequency, nocturia, urgency, bladder pain, dysuria, and sometimes hematuria. Evaluation of the pathophysiological mechanism of bladder voiding dysfunction in ketamine-induced cystitis (KIC) patients is a critical step for therapy. This study uses autophagy inducer (rapamycin, mTOR inhibitor) and inhibitor (wortmannin, PI3K-III inhibitor) to identify the role of autophagy in bladder angiogenesis alteration and bladder hyperactivity improvement.

Abstract

The present study attempts to elucidate whether autophagy alters bladder angiogenesis, decreases inflammatory response, and ameliorates bladder hyperactivity—thereby influencing bladder function in ketamine-induced cystitis (KIC). In our methodology, female Sprague-Dawley (S-D) rats were randomly divided into the control group, the ketamine group, the ketamine+rapamycin group, and the ketamine+wortmannin group. The bladder function, contractile activity of detrusor smooth muscle, distribution of autophagosome and autolysosome, total white blood cells (WBCs) and leukocyte differential counts, the expressions of autophagy-associated protein, angiogenesis markers, and signaling pathway molecules involved in KIC were tested, respectively. The data revealed that treatment with ketamine significantly results in bladder overactivity, enhanced interstitial fibrosis, impaired endothelium, induced eosinophil-mediated inflammation, swelling, and degraded mitochondria and organelles, inhibited angiogenesis, and elevated the phosphorylation of Akt. However, treatment with rapamycin caused an inhibitory effect on vascular formation, removed ketamine metabolites, decreased the eosinophil-mediated inflammation, and ameliorated bladder hyperactivity, leading to improve bladder function in KIC. Moreover, wortmannin treatment reduced basophil-mediated inflammatory response, improved bladder angiogenesis by increasing capillary density and VEGF expression, to reverse antiangiogenic effect to repair KIC. In conclusion, these findings suggested that autophagy could modulate inflammatory responses and angiogenesis, which improved bladder function in KIC.

Astragaloside IV-targeting miRNA-1 attenuates lipopolysaccharide-induced cardiac dysfunction in rats through inhibition of apoptosis and autophagy

Astragaloside IV (AS-IV), the major active constituent purified from Astragalus membranaceus, was previously reported to have protective effects against cardiac dysfunction. However, the underlying mechanism remains unknown. In the present study, we investigated the protective effect of AS-IV on lipopolysaccharide (LPS)-induced cardiac dysfunction and explored the potential mechanism by focusing on miRNA-1 (miR-1) at the animal and cellular levels. A series of methods were used, including echocardiography, flow cytometry, ELISA, immunofluorescence, transmission electron microscopy, RT-PCR, and western blotting. The results showed that both AS-IV and the miR-1 inhibitor improved cardiac dysfunction, reduced heart injury, inhibited apoptosis and autophagy, and regulated the expression of calcium- and mitochondrial energy metabolism-related proteins in the heart tissue of rats treated with LPS. Importantly, AS-IV downregulated the expression of miR-1 mRNA in heart tissue. All effects of AS-IV were at least partly abolished by miR-1 mimics. In the in vitro study, both AS-IV and the miR-1 inhibitor inhibited apoptosis and autophagy and regulated the expression of calcium- and mitochondrial energy metabolism-related proteins in heart cells treated with LPS. Similarly, AS-IV downregulated the expression of miR-1 mRNA in heart cells. All effects of AS-IV on cells were at least partly abolished by miR-1 mimics. Furthermore, miR-1 mimics exhibited effects similar to LPS both in animal and cellular studies. Taken together, these results suggest that AS-IV protects against LPS-induced cardiac dysfunction by inhibiting calcium-mediated apoptosis and autophagy by targeting miR-1, highlighting a new mechanism for the therapeutic effect of AS-IV on cardiac dysfunction.

Zerumin A attenuates the inflammatory responses in LPS-stimulated H9c2 cardiomyoblasts

Zerumin A (ZA) is one of the potential components of Curcuma amada rhizomes, and it has been shown to possess a variety of pharmacological activities. This study deals with the beneficial activity of ZA in lipopolysaccharide (LPS)-stimulated inflammation in H9c2 cardiomyoblasts. Herein, H9c2 cells were preincubated with ZA for 1 h and stimulated with LPS for 24 h. The cells were analyzed for the expression of various pro-inflammatory mediators and signaling molecules. Results showed that the cell viability was significantly improved and reactive oxygen species production was alleviated remarkably with ZA pretreatment. We also found that ZA pretreatment significantly suppressed the upregulation of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2) protein levels, and nitric oxide (NO) release in LPS-stimulated cells. In addition, ZA significantly ameliorated LPS-elicited overexpression of pro-inflammatory chemokines and cytokines such as monocyte chemoattractant protein-1 (MCP-1), tumor necrosis factor α (TNF- α), interferon-γ (IFN-γ), and interleukin-1 (IL-1) in H9c2 cells, and it upregulated the synthesis of the anti-inflammatory cytokine interleukin-10 (IL-10). Moreover, pretreatment with ZA and the mitogen-activated protein kinases (MAPK) pathway inhibitors also reduced the phosphorylation of extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinases (JNK), and p38. ZA significantly inhibited IkB-a phosphorylation and nuclear factor (NF)-kB p65 subunit translocation into nuclei. Overall data demonstrated that ZA protects cardiomyocytes against LPS injury by inhibiting NF-kB p65 activation via the MAPK signaling pathway in vitro. These findings suggest that ZA may be a promising agent for a detailed study for the prevention or treatment of myocardial dysfunction in sepsis.

Fat-1 transgenic mice rich in endogenous omega-3 fatty acids are protected from lipopolysaccharide-induced cardiac dysfunction

Aims

Cardiac malfunctions developing in result of sepsis are hard to treat so they eventually contribute to the increased mortality. Previous reports indicated for therapeutic potential of exogenous ω‐3 polyunsaturated fatty acids (PUFA) in sepsis, but potential benefits of this compound on the malfunctional heart have not been explored yet. In the present study, we investigated whether the constantly elevated levels of endogenous ω‐3 PUFA in transgenic fat‐1 mice would alleviate the lipopolysaccharide (LPS)‐induced cardiac failure and death.

Methods and results

After both wild type (WT) and transgenic fat‐1 mice were challenged with LPS, a Kaplan–Meier curve and echocardiography were performed to evaluate the survival rates and cardiac function. Proteomics analysis, RT‐PCR, western blotting, immune‐histochemistry, and transmission electron microscopy were further performed to investigate the underlying mechanisms. Results showed that transgenic fat‐1 mice exhibited the significantly lower mortality after LPS challenge as compared with their WT counterparts (30% vs. 42.5%, P < 0.05). LPS injection consistently impaired the left ventricular contractile function and caused the cardiac injury in the wild type mice, but not significantly affected the fat‐1 mice (P < 0.05). Proteomic analyses, ELISA, and immunohistochemistry further revealed that myocardium of the LPS‐challenged fat‐1 mice demonstrated the significantly lower levels of pro‐inflammatory markers and ROS than WT mice. Meaningfully, the LPS‐treated fat‐1 mice also demonstrated a significantly higher levels of LC3 II/I and Atg7 expressions than the LPS‐treated WT mice (P < 0.05), as well as displayed a selectively increased levels of peroxisome proliferator‐activated receptor (PPAR) γ and sirtuin (Sirt)‐1 expression, associated with a parallel decrease in NFκB activation.

Conclusions

The fat‐1 mice were protected from the detrimental LPS‐induced inflammation and oxidative stress, and exhibited enhancement of the autophagic flux activities, associating with the increased Sirt‐1 and PPARγ signals.

Mitophagy receptor FUNDC1 is regulated by PGC-1α/NRF1 to fine tune mitochondrial homeostasis

Mitophagy is an essential cellular autophagic process that selectively removes superfluous and damaged mitochondria, and it is coordinated with mitochondrial biogenesis to fine tune the quantity and quality of mitochondria. Coordination between these two opposing processes to maintain the functional mitochondrial network is of paramount importance for normal cellular and organismal metabolism. However, the underlying mechanism is not completely understood. Here we report that PGC-1α and nuclear respiratory factor 1 (NRF1), master regulators of mitochondrial biogenesis and metabolic adaptation, also transcriptionally upregulate the gene encoding FUNDC1, a previously characterized mitophagy receptor, in response to cold stress in brown fat tissue. NRF1 binds to the classic consensus site in the promoter of Fundc1 to upregulate its expression and to enhance mitophagy through its interaction with LC3. Specific knockout of Fundc1 in BAT results in reduced mitochondrial turnover and accumulation of functionally compromised mitochondria, leading to impaired adaptive thermogenesis. Our results demonstrate that FUNDC1-dependent mitophagy is directly coupled with mitochondrial biogenesis through the PGC-1α/NRF1 pathway, which dictates mitochondrial quantity, quality, and turnover and contributes to adaptive thermogenesis.

Natural Antioxidants Improve the Vulnerability of Cardiomyocytes and Vascular Endothelial Cells under Stress Conditions: A Focus on Mitochondrial Quality Control

Cardiovascular disease has become one of the main causes of human death. In addition, many cardiovascular diseases are accompanied by a series of irreversible damages that lead to organ and vascular complications. In recent years, the potential therapeutic strategy of natural antioxidants in the treatment of cardiovascular diseases through mitochondrial quality control has received extensive attention. Mitochondria are the main site of energy metabolism in eukaryotic cells, including myocardial and vascular endothelial cells. Mitochondrial quality control processes ensure normal activities of mitochondria and cells by maintaining stable mitochondrial quantity and quality, thus protecting myocardial and endothelial cells against stress. Various stresses can affect mitochondrial morphology and function. Natural antioxidants extracted from plants and natural medicines are becoming increasingly common in the clinical treatment of diseases, especially in the treatment of cardiovascular diseases. Natural antioxidants can effectively protect myocardial and endothelial cells from stress-induced injury by regulating mitochondrial quality control, and their safety and effectiveness have been preliminarily verified. This review summarises the damage mechanisms of various stresses in cardiomyocytes and vascular endothelial cells and the mechanisms of natural antioxidants in improving the vulnerability of these cell types to stress by regulating mitochondrial quality control. This review is aimed at paving the way for novel treatments for cardiovascular diseases and the development of natural antioxidant drugs.

Heat shock protein 22 modulates NRF1/TFAM-dependent mitochondrial biogenesis and DRP1-sparked mitochondrial apoptosis through AMPK-PGC1α signaling pathway to alleviate the early brain injury of subarachnoid hemorrhage in rats

Mitochondrial dysfunction has been widely accepted as a detrimental factor in subarachnoid hemorrhage (SAH)-induced early brain injury (EBI), which is eminently related to poor neurologic function outcome. Previous studies have revealed that enhancement of heat shock protein 22 (hsp22) under conditions of stress is a friendly mediator of mitochondrial homeostasis, oxidative stress and apoptosis, thus accelerating neurological recovery. However, no study has confirmed whether hsp22 attenuates mitochondrial stress and apoptosis in the setting of SAH-induced EBI. Our results indicated that endogenous hsp22, p-AMPK/AMPK, PGC1α, TFAM, Nrf1 and Drp1 were significantly upregulated in cortical neurons in response to SAH, accompanied by neurologic impairment, brain edema, neuronal degeneration, lower level of mtDNA and ATP, mitochondria-cytosol translocation of cytochrome c, oxidative injury and caspase 3-involved mitochondrial apoptosis. However, exogenous hsp22 maintained neurological function, reduced brain edema, improved oxidative stress and mitochondrial apoptosis, these effects were highly dependent on PGC1α-related mitochondrial biogenesis/fission, as evidenced by co-application of PGC1α siRNA. Furthermore, we demonstrated that blockade of AMPK with dorsomorphin also compromised the neuroprotective actions of hsp22, along with the alterations of PGC1α and its associated pathway molecules. These data revealed that hsp22 exerted neuroprotective effects by salvaging mitochondrial function in an AMPK-PGC1α dependent manner, which modulates TFAM/Nrf1-induced mitochondrial biogenesis with positive feedback and DRP1-triggered mitochondrial apoptosis with negative feedback, further reducing oxidative stress and brain injury. Boosting the biogenesis and repressing excessive fission of mitochondria by hsp22 may be an efficient treatment to relieve SAH-elicited EBI.

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Hsp22 is notably upregulated in neurons at 24 h after SAH.

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Hsp22 boosts the NRF1/TFAM-dependent mitochondrial biogenesis.

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Hsp22 represses DRP1-sparked mitochondrial apoptosis.

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AMPK-PGC1α pathway is involved in hsp22-mediated neuroprotection after SAH.

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Modulation of mitochondrial biogenesis and fission may be efficient for treating SAH.

Mitochondrial dysfunction in sepsis is associated with diminished intramitochondrial TFAM despite its increased cellular expression

Sepsis is characterized by a dysregulated immune response, metabolic derangements and bioenergetic failure. These alterations are closely associated with a profound and persisting mitochondrial dysfunction. This however occurs despite increased expression of the nuclear-encoded transcription factor A (TFAM) that normally supports mitochondrial biogenesis and functional recovery. Since this paradox may relate to an altered intracellular distribution of TFAM in sepsis, we tested the hypothesis that enhanced extramitochondrial TFAM expression does not translate into increased intramitochondrial TFAM abundance. Accordingly, we prospectively analyzed PBMCs both from septic patients (n = 10) and lipopolysaccharide stimulated PBMCs from healthy volunteers (n = 20). Extramitochondrial TFAM protein expression in sepsis patients was 1.8-fold greater compared to controls (p = 0.001), whereas intramitochondrial TFAM abundance was approximate 80% less (p < 0.001). This was accompanied by lower mitochondrial DNA copy numbers (p < 0.001), mtND1 expression (p < 0.001) and cellular ATP content (p < 0.001) in sepsis patients. These findings were mirrored in lipopolysaccharide stimulated PBMCs taken from healthy volunteers. Furthermore, TFAM-TFB2M protein interaction within the human mitochondrial core transcription initiation complex, was 74% lower in septic patients (p < 0.001). In conclusion, our findings, which demonstrate a diminished mitochondrial TFAM abundance in sepsis and endotoxemia, may help to explain the paradox of lacking bioenergetic recovery despite enhanced TFAM expression.

Mitophagy, Mitochondrial Homeostasis, and Cell Fate

Mitochondria are highly plastic and dynamic organelles that have graded responses to the changing cellular, environmental, and developmental cues. Mitochondria undergo constant mitochondrial fission and fusion, mitochondrial biogenesis, and mitophagy, which coordinately control mitochondrial morphology, quantity, quality, turnover, and inheritance. Mitophagy is a cellular process that selectively removes the aged and damaged mitochondria via the specific sequestration and engulfment of mitochondria for subsequent lysosomal degradation. It plays a pivotal role in reinstating cellular homeostasis in normal physiology and conditions of stress. Damaged mitochondria may either instigate innate immunity through the overproduction of ROS or the release of mtDNA, or trigger cell death through the release of cytochrome c and other apoptogenic factors when mitochondria damage is beyond repair. Distinct molecular machineries and signaling pathways are found to regulate these mitochondrial dynamics and behaviors. It is less clear how mitochondrial behaviors are coordinated at molecular levels. BCL2 family proteins interact within family members to regulate mitochondrial outer membrane permeabilization and apoptosis. They were also described as global regulators of mitochondrial homeostasis and mitochondrial fate through their interaction with distinct partners including Drp1, mitofusins, PGAM5, and even LC3 that involved mitochondrial dynamics and behaviors. In this review, we summarize recent findings on molecular pathways governing mitophagy and its coordination with other mitochondrial behaviors, which together determine cellular fate.

Eupafolin ameliorates lipopolysaccharide-induced cardiomyocyte autophagy via PI3K/AKT/mTOR signaling pathway

Objective(s):

Eupafolin, a major active component of Eupatorium perfoliatum L., has anti-inflammatory and anti-oxidant properties. Lipopolysaccharide (LPS) is responsible for myocardial depression. A line of evidences revealed that LPS induces autophagy in cardiomyocytes injury. This study aims to evaluate the effects of eupafolin on LPS-induced cardiomyocyte autophagy.

Materials and Methods:

The effect of LPS on cell viability was examined by CCK-8. Autophagic protein 2 light chain 3 (LC3II), which was regulated by LPS and eupafolin, was examined using immunofluorescent staining. The expression levels of Beclin-1 and p62 were detected by western blotting. The effects of eupafolin on phosphatidylinositol-3-kinase/ protein kinase B/ mammalian target of rapamycin (PI3K/AKT/mTOR) signaling pathway were also evaluated by western blotting and immunofluorescent staining.

Results:

Eupafolin pretreatment reduced the expression of LC3II and Beclin-1, whereas p62 was significant increased. In addition, eupafolin promoted expression of PI3K/AKT/mTOR signaling pathway and mTOR inhibitor rapamycin reversed the inhibitory effects on LPS-induced cardiomyocyte autophagy.

Conclusion:

Eupafolin exerts anti-autophagy activity via activation of PI3K/AKT/mTOR signaling pathway.

Induction of autophagy protects human dental pulp cells from lipopolysaccharide-induced pyroptotic cell death

The NOD-like receptor protein 3/caspase-1 inflammasome can be activated in human dental pulp tissue and fibroblasts; however, the underlying mechanisms are poorly understood. In the present study, lipopolysaccharide (LPS) was used to treat dental pulp cells to establish an inflammation model. Cell viability was examined by sulforhodamine B assay. Interleukin (IL)-1β, caspase-1, microtubule-associated protein-1 light chain 3-II/I and p62 were determined by western blotting and ELISA. The phosphorylation (p-) levels of NF-κB and NF-κB inhibitor (IκB)α protein were observed by western blotting. The results demonstrated that LPS induced pyroptotic cell death in cultured dental pulp cells, which was supported by the increased levels of IL-1β, IL-18 and caspase-1. Rapamycin and 3-methyladenine (3-MA) were used to activate and inhibit autophagy, and it was observed that LPS increased autophagy and rapamycin reduced LPS-induced dental pulp cell pyroptosis. However, 3-MA aggravated LPS-induced dental pulp cell pyroptosis. In addition, LPS inhibited the expression of IκBα, but increased the expression of p-NF-κB. Compared with the LPS group, 3-MA further inhibited the expression of IκBα but promoted the expression of p-NF-κB. However, rapamycin produced the opposite results to LPS. Under LPS treatment, the NF-κB pathway inhibitor BAY11-7082 further enhanced the inhibitory effects of rapamycin, but inhibited the promoting effects of 3-MA on the protein expression levels of IL-1β and caspase-1. The results of the present study demonstrated that there is an important crosstalk between autophagy, pyroptosis and the NF-κB pathway, and that the modulation of pyroptosis in dental pulp cells may be a promising strategy to pulpitis therapy.

Effect of gomisin A on osteoblast differentiation in high glucose-mediated oxidative stress

BACKGROUND

Gomisin A is a lignan isolated from the hexane of Schisandra chinensis fruit extract with antioxidant properties. Oxidative stress mediated by high glucose is one of the major complications of diabetes mellitus.

PURPOSE

This study investigates the role of gomisin A in osteoblast differentiation under high glucose-induced oxidative stress in MC3T3 E1 cells and determines its relationship with heme oxygenase-1 (HO-1) and mitochondrial biogenesis.

METHODS

MC3T3 E1 cells were treated by gomisin A following induced by high glucose levels and glucose oxidase to investigate the inhibitory effect of gomisin A against high glucose oxidative stress. Western blot analysis, alizarin red staining, alkaline phosphatase (ALP) activity, analysis of reactive oxygen species (ROS) and confocal microscopy were used to determine mitochondrial biogenesis, oxidative stress, osteoblast differentiation and mineralization. To analyze the role of HO-1, the MC3T3 E1 cells were treated with the HO-1 inhibitor zinc protoporphyrin IX (ZnPP).

RESULTS

Gomisin A enhanced the expression of HO-1, increased mitochondrial biogenesis factors (peroxisome proliferator-activated receptor gamma coactivator 1-alpha, nuclear respiratory factor-1, and mitochondrial transcription factor A), antioxidant enzymes (copper-zinc superoxide dismutases and manganese superoxide dismutase), osteoblast differentiation molecules (bone morphogenic protein-2/7, osteoprotegerin and Runt-related transcription factor-2) and mineralization by upregulation of ALP and alizarin red staining, which were decreased by ZnPP and high glucose oxidative stress. Similarly, gomisin A inhibited ROS which was increased by ZnPP and the high glucose-mediated oxidative stress.

CONCLUSIONS

The findings demonstrated the antioxidative effects of gomisin A, and its role in mitochondrial biogenesis and osteoblast differentiation. It potentially regulated osteoblast differentiation under high glucose-induced oxidative stress via upregulation of HO-1 and maintenance of mitochondrial homeostasis. Thus, gomisin A may represent a potential therapeutic agent for prevention of bone fragility fractures and implant failure triggered by diabetes.

Autophagy and Myocardial Ischemia

Myocardial ischemia and reperfusion cause injury to the heart in myocardial ischemic disease. Both processes increase autophagy. In this chapter, we will provide an overview of the autophagic mechanism caused by myocardial ischemia/reperfusion injury and the role of autophagy in myocardial ischemia/reperfusion injury.

Tumor susceptibility gene 101 ameliorates endotoxin-induced cardiac dysfunction by enhancing Parkin-mediated mitophagy

Cardiac mitochondrial damage and subsequent inflammation are hallmarks of endotoxin-induced myocardial depression. Activation of the Parkin/PTEN-induced kinase 1 (PINK1) pathway has been shown to promote autophagy of damaged mitochondria (mitophagy) and to protect from endotoxin-induced cardiac dysfunction. Tumor susceptibility gene 101 (TSG101) is a key member of the endosomal recycling complexes required for transport, which may affect autophagic flux. In this study, we investigated whether TSG101 regulates mitophagy and influences the outcomes of endotoxin-induced myocardial dysfunction. TSG101 transgenic and knockdown mice underwent endotoxin/lipopolysaccharide treatment (10 μg/g) and were assessed for survival, cardiac function, systemic/local inflammation, and activity of mitophagy mediators in the heart. Upon endotoxin challenge and compared with WT mice, TSG101 transgenic mice exhibited increased survival, preserved cardiac contractile function, reduced inflammation, and enhanced mitophagy activation in the heart. By contrast, TSG101 knockdown mice displayed opposite phenotypes during endotoxemia. Mechanistically, both coimmunoprecipitation assays and coimmunofluorescence staining revealed that TSG101 directly binds to Parkin in the cytosol of myocytes and facilitates translocation of Parkin from the cytosol to the mitochondria. Our results indicate that TSG101 elevation could protect against endotoxin-triggered myocardial injury by promoting Parkin-induced mitophagy.

Age-Dependent Myocardial Dysfunction in Critically Ill Patients: Role of Mitochondrial Dysfunction

Myocardial dysfunction is common in septic shock and post-cardiac arrest but manifests differently in pediatric and adult patients. By conventional echocardiographic parameters, biventricular systolic dysfunction is more prevalent in children with septic shock, though strain imaging reveals that myocardial injury may be more common in adults than previously thought. In contrast, diastolic dysfunction in general and post-arrest myocardial systolic dysfunction appear to be more widespread in the adult population. A growing body of evidence suggests that mitochondrial dysfunction mediates myocardial depression in critical illness; alterations in mitochondrial electron transport system function, bioenergetic production, oxidative and nitrosative stress, uncoupling, mitochondrial permeability transition, fusion, fission, biogenesis, and autophagy all may play key pathophysiologic roles. In this review we summarize the epidemiologic and clinical phenotypes of myocardial dysfunction in septic shock and post-cardiac arrest and the multifaceted manifestations of mitochondrial injury in these disease processes. Since neonatal and pediatric-specific data for mitochondrial dysfunction remain sparse, conclusive age-dependent differences are not clear; instead, we highlight what evidence exists and identify gaps in knowledge to guide future research. Finally, since focal ischemic injury (with or without reperfusion) leading to myocardial infarction is predominantly an atherosclerotic disease of the elderly, this review focuses specifically on septic shock and global ischemia-reperfusion injury occurring after resuscitation from cardiac arrest.

Autophagy Enhancing Contributes to the Organ Protective Effect of Alpha-Lipoic Acid in Septic Rats

Alpha-lipoic acid (ALA) reportedly has protective effects against sepsis, which is a leading cause of mortality worldwide and is associated with multiple organ dysfunction. The present study aimed to investigate further the possible action mechanisms of ALA. Male Sprague-Dawley rats were subjected to cecal ligation and puncture (CLP) in order to establish a sepsis model. The rats received an oral gavage of 200 mg/kg ALA or saline immediately after surgery. The heart rate (HR), left ventricular systolic pressure (LVSP), left ventricular end-diastolic pressure (LVEDP) and maximum rising and lowering rates of left ventricular pressure (±dp/dt) were examined for assessing the cardiac function. Blood urea nitrogen (BUN) and serum creatinine levels were assessed for evaluating renal function. Neutrophil gelatinase-associated lipocalin (NAGL) was examined for reflecting acute renal injury. Histopathological alterations of the small intestine were examined by hematoxylin-eosin staining. The ultrastructure of the small intestine and kidney was observed under electron microscopy. The levels of autophagy- and inflammation-associated proteins were determined via western blot analysis. The binding of nuclear factor-kappa B (NF-κB) to DNA was tested via an electrophoretic mobility shift assay. Cell apoptosis was examined using TUNEL staining. ALA treatment improved the survival rate, restored the loss of body weight and pro-inflammatory cytokines production in the serum of CLP-induced septic rats. ALA improved the cardiac and renal functions, downregulated the expression levels of interleukin-1β, tumor necrosis factor-α, and inducible nitric oxide synthase in the myocardium and small intestine of septic rats. ALA treatment also inactivated the NF-κB signaling pathway in the small intestine. An examination of autophagy showed that ALA increased the LC3II/I ratio, upregulated Atg5, Atg7, and beclin-1 and downregulated p62 protein levels in the myocardium, kidney, and small intestine of septic rats, and further promoted autophagosome accumulation in the kidney and small intestine. In addition, ALA could also reduce cell apoptosis in myocardium, kidney and small intestine tissues. These effects can be completely or party inhibited by 3-MA. Our findings suggest that autophagy enhancing may contribute to the organ protective effect of ALA in septic rats.

Upregulation of UCP2 Expression Protects against LPS-Induced Oxidative Stress and Apoptosis in Cardiomyocytes

Uncoupling protein 2 (UCP2) has a cardioprotective role under septic conditions, but the underlying mechanism remains unclear. This study aimed at investigating the effects of UCP2 on the oxidative stress and apoptosis of cardiomyocytes induced by lipopolysaccharide (LPS). First, LPS increased UCP2 expression in cardiomyocytes in a time-dependent manner. LPS increased the production of lactate dehydrogenase (LDH), reactive oxygen species (ROS), and malondialdehyde (MDA) and decreased the level of superoxide dismutase (SOD). However, UCP2 knockdown increased the LPS-induced cardiac injury and oxidative stress. In addition, LPS damaged the mitochondrial ultrastructure and led to the disruption of mitochondrial membrane potential (MMP), as well as the release of mitochondrial cytochrome c. UCP2 knockdown aggravated mitochondrial injury and the release of mitochondrial cytochrome c. LPS increased the protein levels of Bax and cleaved-caspase-3, decreased the protein level of Bcl-2, and upregulated the protein level of mitogen-activated protein kinase. However, upon UCP2 knockdown, the protein levels of Bax and cleaved-caspase-3 increased even further, and the protein level of Bcl-2 was further decreased. The protein level of phosphorylated p38 was also further enhanced. Thus, UCP2 protects against LPS-induced oxidative stress and apoptosis in cardiomyocytes.

MicroRNA Let-7d-3p Contributes to Cardiac Protection via Targeting HMGA2

We tested the hypothesis that Let-7d-3p contributes to cardiac cell protection during hypoxic challenge. Myoblast H9c2 cells and primary neonatal rat ventricular cardiomyocytes (NRVM) were transfected with five selected miRNA mimics. Both cell lines were subjected to 0.2% oxygen hypoxia. The protective effects of these miRNAs were determined by assessment of cell metabolic activity by CCK8 assay and measurement of lactate dehydrogenase (LDH) release as a marker of cell injury. Apoptosis and autophagy flux were assessed by Annexin V/7-AAD double staining and the ratio of LC3 II/I with Baf-A1 treatment, an autophagy flux inhibitor, respectively. Luciferase-reporter assay, RT-qPCR and Western blots were performed to identify the changes of relevant gene targets. Among five miRNA mimic transfections, Let-7d-3p increased CCK8 activity, and decreased LDH release in both H9c2 and NRVM during hypoxia. Apoptosis was significantly reduced in H9c2 cells transfected with Let-7d-3p mimic. Autophagy and autophagy flux were not affected. In silico, mRNAs of HMGA2, YY1, KLF9, KLF12, and MEX3C are predicted targets for Let-7d-3p. Luciferase-reporter assay confirmed that Let-7d-3p bound directly to the 3’-UTR region of HMGA2, MEX3C, and YY1, the down-regulations of these mRNAs were verified in both H9c2 and NRVM. The protein expression of HMGA2, but not others, was downregulated in H9c2 and NRVM. It is known that HMGA2 is a strong apoptosis trigger through the blocking of DNA repair. Thus, we speculate that the anti-apoptotic effects of Let-7d-3p mimic during hypoxia challenge are due to direct targeting of HMGA2.

HDAC inhibition induces autophagy and mitochondrial biogenesis to maintain mitochondrial homeostasis during cardiac ischemia/reperfusion injury

AIMS

The FDA-approved histone deacetylase (HDAC) inhibitor, suberoylanilide hydroxamic acid (SAHA, Vorinostat) has been shown to induce cardiomyocyte autophagy and blunt ischemia/reperfusion (I/R) injury when administered at the time of reperfusion. However, the precise mechanisms underlying the cardioprotective activity of SAHA are unknown. Mitochondrial dysfunction and oxidative damage are major contributors to myocardial apoptosis during I/R injury. We hypothesize that SAHA protects the myocardium by maintaining mitochondrial homeostasis and reducing reactive oxygen species (ROS) production during I/R injury.

METHODS

Mouse and cultured cardiomyocytes (neonatal rat ventricular myocytes and human embryonic stem cell-derived cardiomyocytes) I/R models were used to investigate the effects of SAHA on mitochondria. ATG7 knockout mice, ATG7 knockdown by siRNA and PGC-1α knockdown by adenovirus in cardiomyocytes were used to test the dependency of autophagy and PGC-1α-mediated mitochondrial biogenesis respectively.

RESULTS

Intact and total mitochondrial DNA (mtDNA) content and mitochondrial mass were significantly increased in cardiomyocytes by SAHA pretreatment before simulated I/R. In vivo, I/R induced >50% loss of mtDNA content in the border zones of mouse hearts, but SAHA pretreatment and reperfusion treatment alone reverted mtDNA content and mitochondrial mass to control levels. Moreover, pretreatment of cardiomyocytes with SAHA resulted in a 4-fold decrease in I/R-induced loss of mitochondrial membrane potential and a 25%-40% reduction in cytosolic ROS levels. However, loss-of-function of ATG7 in cardiomyocytes or mouse myocardium abolished the protective effects of SAHA on ROS levels, mitochondrial membrane potential, mtDNA levels, and mitochondrial mass. Lastly, PGC-1α gene expression was induced by SAHA in NRVMs and mouse heart subjected to I/R, and loss of PGC-1α abrogated SAHA's mitochondrial protective effects in cardiomyocytes.

CONCLUSIONS

SAHA prevents I/R induced-mitochondrial dysfunction and loss, and reduces myocardial ROS production when given before or after the ischemia. The protective effects of SAHA on mitochondria are dependent on autophagy and PGC-1α-mediated mitochondrial biogenesis.

The role of mitochondria in sepsis-induced cardiomyopathy

Sepsis is defined as a life-threatening organ dysfunction caused by a dysregulated host response to infection. Myocardial dysfunction, often termed sepsis-induced cardiomyopathy, is a frequent complication and is associated with worse outcomes. Numerous mechanisms contribute to sepsis-induced cardiomyopathy and a growing body of evidence suggests that bioenergetic and metabolic derangements play a central role in its development; however, there are significant discrepancies in the literature, perhaps reflecting variability in the experimental models employed or in the host response to sepsis. The condition is characterised by lack of significant cell death, normal tissue oxygen levels and, in survivors, reversibility of organ dysfunction. The functional changes observed in cardiac tissue may represent an adaptive response to prolonged stress that limits cell death, improving the potential for recovery. In this review, we describe our current understanding of the pathophysiology underlying myocardial dysfunction in sepsis, with a focus on disrupted mitochondrial processes.

Schisandrin C enhances odontoblastic differentiation through autophagy and mitochondrial biogenesis in human dental pulp cells

OBJECTIVE

To investigate the role of Schisandrin C in odontoblastic differentiation, and its relations between autophagy and mitochondrial biogenesis in human dental pulp cells (HPDCs).

DESIGN

Fresh third molars were used, and cultured for HDPCs. Western blotting technique, Alizarin red S staining, alkaline phosphatase (ALP) activity, and confocal microscopy were used to detect autophagy, mitochondrial biogenesis, and odontoblastic differentiation. To understand the mechanism of Schisandrin C, the HDPCs were treated with lipopolysaccharide (LPS), autophagy and heme oxygenase-1 (HO-1) inhibitors: 3-Methyladenine (3-MA) and Zinc protoporphyrin IX (ZnPP), respectively.

RESULTS

LPS decreased the expression of autophagy molecules [autophagy protein 5 (ATG-5), beclin-1, and microtubule-associated protein 1A/1B light chain 3 (LC3-I/II)] and mitochondrial biogenesis molecules [heme oxygenase-1 (HO-1) and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α)], and disrupted odontoblastic differentiation. The down-regulation of autophagy and mitochondrial biogenesis with 3-MA and ZnPP inhibited odontoblastic differentiation. However, Schisandrin C restored the expression of all the above molecules, even with LPS and inhibitor treatment. This result demonstrates that autophagy and mitochondrial biogenesis plays an essential role in odontoblastic differentiation, and Schisandrin C activates these systems to promote odontoblastic differentiation of HDPCs.

CONCLUSION

Schisandrin C has potential characters to regulate odontoblastic differentiation, and may be recommended for use as a compound for pulp homeostasis.

The TLR4 Agonist Monophosphoryl Lipid A Drives Broad Resistance to Infection via Dynamic Reprogramming of Macrophage Metabolism

Monophosphoryl lipid A (MPLA) is a clinically used TLR4 agonist that has been found to drive nonspecific resistance to infection for up to 2 wk. However, the molecular mechanisms conferring protection are not well understood. In this study, we found that MPLA prompts resistance to infection, in part, by inducing a sustained and dynamic metabolic program in macrophages that supports improved pathogen clearance. Mice treated with MPLA had enhanced resistance to infection with Staphylococcus aureus and Candida albicans that was associated with augmented microbial clearance and organ protection. Tissue macrophages, which exhibited augmented phagocytosis and respiratory burst after MPLA treatment, were required for the beneficial effects of MPLA. Further analysis of the macrophage phenotype revealed that early TLR4-driven aerobic glycolysis was later coupled with mitochondrial biogenesis, enhanced malate shuttling, and increased mitochondrial ATP production. This metabolic program was initiated by overlapping and redundant contributions of MyD88- and TRIF-dependent signaling pathways as well as downstream mTOR activation. Blockade of mTOR signaling inhibited the development of the metabolic and functional macrophage phenotype and ablated MPLA-induced resistance to infection in vivo. Our findings reveal that MPLA drives macrophage metabolic reprogramming that evolves over a period of days to support a macrophage phenotype highly effective at mediating microbe clearance and that this results in nonspecific resistance to infection.

Mitochondrial pathways to cardiac recovery: TFAM

Mitochondrial dysfunction underlines a multitude of pathologies; however, studies are scarce that rescue the mitochondria for cellular resuscitation. Exploration into the protective role of mitochondrial transcription factor A (TFAM) and its mitochondrial functions respective to cardiomyocyte death are in need of further investigation. TFAM is a gene regulator that acts to mitigate calcium mishandling and ROS production by wrapping around mitochondrial DNA (mtDNA) complexes. TFAM's regulatory functions over serca2a, NFAT, and Lon protease contribute to cardiomyocyte stability. Calcium- and ROS-dependent proteases, calpains, and matrix metalloproteinases (MMPs) are abundantly found upregulated in the failing heart. TFAM's regulatory role over ROS production and calcium mishandling leads to further investigation into the cardioprotective role of exogenous TFAM. In an effort to restabilize physiological and contractile activity of cardiomyocytes in HF models, we propose that TFAM-packed exosomes (TFAM-PE) will act therapeutically by mitigating mitochondrial dysfunction. Notably, this is the first mention of exosomal delivery of transcription factors in the literature. Here we elucidate the role of TFAM in mitochondrial rescue and focus on its therapeutic potential.

Autophagy maintains the integrity of endothelial barrier in LPS-induced lung injury

Understanding the role and underlying regulation mechanism of autophagy in lipopolysaccharide-induced lung injury (LPS-LI) may provide potentially new pharmacological targets for treatment of acute lung injury. The aim of this study was to investigate the functional significance of autophagy in LPS-LI. The autophagy of human pulmonary microvascular endothelial cells (HPMVECs) and mice was inhibited before they were challenged with LPS. In vitro, permeability, vitality, and the LDH release rate of the cells were detected, the zonula occluden-1 (ZO-1) expression and the stress fiber formation were determined. In vivo, the lung injury was assessed. We found LPS caused high permeability and increased lactate dehydrogenase (LDH) release rate, lowered viability of the cells, inhibited the ZO-1 expression and induced stress fiber formation, these effects were further aggravated by prohibiting the level of autophagy. Consistently, in in vivo experiments, LPS-induced serious lung injury, which was reflected as edema, leukocyte infiltration and hemorrhage in lung tissue, and the high concentration of pro-inflammation cytokines tumor necrosis factor (TNF)-α and interleukin (IL)-1β in bronchoalveolar lavage fluid (BALF). Inhibiting autophagy further exacerbated LPS-LI. It appears that autophagy played a protective role in LPS-LI in part through restricting the injury of lung microvascular barrier.

Involvement of Mitochondrial Disorders in Septic Cardiomyopathy

Sepsis is defined as a life-threatening organ dysfunction caused by a dysregulated host response to infection. It remains a leading cause of death worldwide, despite the development of various therapeutic strategies. Cardiac dysfunction, also referred to as septic cardiomyopathy, is a frequent and well-described complication of sepsis and associated with worse clinical outcomes. Recent research has increased our understanding of the role of mitochondrial dysfunction in the pathophysiology of septic cardiomyopathy. The purpose of this review is to present this evidence as a coherent whole and to highlight future research directions.

Anti-inflammatory and antioxidant properties of Schisandrin C promote mitochondrial biogenesis in human dental pulp cells

AIM

To examine the properties of Schisandrin C as an anti-inflammatory and antioxidant compound, and whether its characteristics promote mitochondrial biogenesis in human dental pulp cells (HDPCs).

METHODOLOGY

HDPCs were extracted from fresh third molars and cultured for experiments. Reactive oxidative stress (ROS) and nitric oxide (NO) formation were analysed by a Muse cell analyser. Western blotting and gelatin zymography were used to identify the presence of antioxidants, as well as anti-inflammatory and mitochondrial biogenesis with specific antibody. An unpaired Student's t-test was used for statistical analysis.

RESULTS

Schisandrin C inhibited lipopolysaccharide-stimulated inflammatory molecules; interleukin 1 beta, tumour necrosis factor alpha, intracellular adhesion molecule-1, vascular cell adhesion molecule-1, matrix metalloproteinase-2 and -9, NO production, ROS formation, nuclear factor kappa B translocation (P < 0.05) through the mitogen-activated protein kinase pathway. Schisandrin C increased the expression of superoxide dismutase enzymes as well as haem oxygenase-1 and peroxisome proliferator-activated receptor gamma coactivator 1-alpha through the phosphorylated-protein kinase B (p-Akt) and nuclear factor erythroid 2-related factor-2 pathways (P < 0.05). The anti-inflammatory and antioxidant properties of Schisandrin C promoted mitochondrial biogenesis.

CONCLUSIONS

Schisandrin C has the potential to reduce inflammation and oxidation and to promote mitochondrial biogenesis. Therefore, Schisandrin C may be considered for use as an anti-inflammatory compound for oral inflammation through mitochondrial biogenesis.

Mitochondria in Ischemic Heart Disease

A core feature of ischemic heart disease is injury to cardiomyocytes (CMC). Ischemic CMC manifest the molecular mechanisms to undergo the major forms of cell injury and death, namely, oncotic necrosis, necroptosis, apoptosis and unregulated autophagy. Important modulators of ischemic injury are reperfusion and conditioning. Mitochondria have a major role in mediating the injury to CMC through membrane protein complexes referred to as death channels. Apoptosis is mediated by activation of a channel regulated by the Bcl-2 protein family leading to mitochondrial outer membrane permeabilization (MOMP). Oncotic type injury is mediated by opening of the mitochondrial permeability transition pore (mPTP). Mitochondria also have a reperfusion salvage kinase pathway (RISK). With cyclosporine A serving as a prototype, ongoing research is aimed at developing pharmacological approaches to condition and preserve mitochondrial integrity in order to promote CMC survival during episodes of myocardial ischemia.