Mitigation of carbon tetrachloride-induced hepatic injury by methylene blue, a repurposed drug, is mediated by dual inhibition of GSK3β downstream of PKA

GSK3-Driven Modulation of Inflammation and Tissue Integrity in the Animal Model

Nowadays, GSK3 is accepted as an enzyme strongly involved in the regulation of inflammation by balancing the pro- and anti-inflammatory responses of cells and organisms, thus influencing the initiation, progression, and resolution of inflammatory processes at multiple levels. Disturbances within its broad functional scope, either intrinsically or extrinsically induced, harbor the risk of profound disruptions to the regular course of the immune response, including the formation of severe inflammation-related diseases. Therefore, this review aims at summarizing and contextualizing the current knowledge derived from animal models to further shape our understanding of GSK3α and β and their roles in the inflammatory process and the occurrence of tissue/organ damage. Following a short recapitulation of structure, function, and regulation of GSK3, we will focus on the lessons learned from GSK3α/β knock-out and knock-in/overexpression models, both conventional and conditional, as well as a variety of (predominantly rodent) disease models reflecting defined pathologic conditions with a significant proportion of inflammation and inflammation-related tissue injury. In summary, the literature suggests that GSK3 acts as a crucial switch driving pro-inflammatory and destructive processes and thus contributes significantly to the pathogenesis of inflammation-associated diseases.

Theaflavine inhibits hepatic stellate cell activation by modulating the PKA/LKB1/AMPK/GSK3β cascade and subsequently enhancing Nrf2 signaling

Activation of hepatic stellate cells (HSCs) constitutes a crucial etiological factor leading to liver fibrosis. Theaflavine (TF) is a characteristic bioactive compound in fermented tea. Here, we found that TF attenuated the activation of LX-2 HSCs induced by transforming growth factor-β1 (TGF-β1). TF potentiated nuclear factor erythroid 2-related Factor 2 (Nrf2) signaling. Knockdown of Nrf2 abrogated TF-mediated resistance to TGF-β1. Liver kinase B1 (LKB1), AMP-activated kinase (AMPK), and glycogen synthase kinase-3β (GSK3β) are upstream regulators of Nrf2. TF modulated the LKB1/AMPK/GSK3β axis. Inhibition of AMPK or knockdown of LKB1 crippled TF-mediated potentiation of Nrf2. Protein kinase A (PKA) catalyzes LKB1 phosphorylation. In LX-2 cells, TF increased the LKB1/PKA interaction without affecting their contents. Inhibition of PKA abolished TF-mediated potentiation of LKB1/Nrf2 and abrogated the inhibitory effects of TF on their activation. TF also enhanced direct binding between purified catalytic subunit α of PKA (PKA-Cα) and LKB1 proteins in vitro. Molecular docking indicated that TF showed binding activity with both LKB1 and PKA-Cα proteins. In mouse primary HSCs, TF elevated LKB1/PKA-Cα binding, boosted LKB1 phosphorylation, potentiated Nrf2 and suppressed their spontaneous activation. PKA inhibition or LKB1 knockdown eliminated TF-mediated induction of Nrf2 and suppression of HSC activation. Furthermore, TF considerably alleviated CCl4-induced mouse liver fibrosis. In mouse livers, TF increased the LKB1/PKA-Cα interaction, upregulated LKB1 phosphorylation and modulated its downstream AMPK/GSK3β/Nrf2 cascade. Our findings collectively indicated that TF suppresses HSC activation. Mechanistically, TF elevated the LKB1/PKA interaction in HSCs, which increased LKB1 phosphorylation and subsequently modulated the downstream AMPK/GSK3β/Nrf2 axis.

Novel pharmacotherapy for burn wounds: what are the advancements

INTRODUCTION

The prognosis for severe burns has improved significantly over the past 50 years. Meanwhile, burns have become an affliction mainly affecting the less well-developed regions of the world. Early excision and skin grafting has led to major improvements in therapeutic outcomes.

AREAS COVERED

The purpose of this article is to survey the use of pharmacotherapy to treat different pathophysiological complications of burn injury. The author, herein, discusses the use of drug treatments for a number of systemic metabolic disturbances including hyperglycemia, elevated catabolism, and gluconeogenesis.

EXPERT OPINION

Advancements in personalized and molecular medicine will make an impact on burn therapy. Similarities between severe burns and other critically ill patients will lead to cross-fertilization between different medical specialties. Furthermore, advances in stem cells and tissue regeneration will lead to improved healing and less lifelong disability. Indeed, research in new drug therapy for burns is actively progressing for many different complications.

From Mitochondrial Function to Neuroprotection-an Emerging Role for Methylene Blue

Methylene blue (MB) is a well-established drug with a long history of use, owing to its diverse range of use and its minimal side effect profile. MB has been used classically for the treatment of malaria, methemoglobinemia, and carbon monoxide poisoning, as well as a histological dye. Its role in the mitochondria, however, has elicited much of its renewed interest in recent years. MB can reroute electrons in the mitochondrial electron transfer chain directly from NADH to cytochrome c, increasing the activity of complex IV and effectively promoting mitochondrial activity while mitigating oxidative stress. In addition to its beneficial effect on mitochondrial protection, MB is also known to have robust effects in mitigating neuroinflammation. Mitochondrial dysfunction has been identified as a seemingly unifying pathological phenomenon across a wide range of neurodegenerative disorders, which thus positions methylene blue as a promising therapeutic. In both in vitro and in vivo studies, MB has shown impressive efficacy in mitigating neurodegeneration and the accompanying behavioral phenotypes in animal models for such conditions as stroke, global cerebral ischemia, Alzheimer's disease, Parkinson's disease, and traumatic brain injury. This review summarizes recent work establishing MB as a promising candidate for neuroprotection, with particular emphasis on the contribution of mitochondrial function to neural health. Furthermore, this review will briefly examine the link between MB, neurogenesis, and improved cognition in respect to age-related cognitive decline.

Protective effects of monosialotetrahexosylganglioside sodium on H2O2-induced human vascular endothelial cells

Monosialotetrahexosylganglioside sodium (GM1) is widely used in the treatment of central and peripheral neurological injuries. In addition to its neuroprotective activity, GM1 exerts protective effects on brain microvascular endothelial cells, although the mechanisms underlying these effects remain unclear. The aim of the present study was to clarify the protective effects and underlying mechanisms of GM1 on human umbilical vein endothelial cells (HUVECs). In this study, hydrogen peroxide (H₂O₂) was applied to induce the HUVEC injury. HUVECs in a logarithmic growth phase were divided into five groups, namely the control, H₂O₂-treated, 10-mg/l GM1, 5-mg/l GM1 and 1-mg/l GM1 groups. In all the groups, cell proliferation was detected using a Cell Counting Kit-8 assay, a flow cytometric method was applied to analyze the cell cycle and nuclear factor (NF)-κB expression was evaluated using immunofluorescence analysis. In addition, the protein expression levels of NF-κB, phosphatidylinositol 3-kinase (PI3K) and glycogen synthase kinase (GSK)-3 were detected via western blot analysis. The results indicated that GM1 exerted significant protective effects on H₂O₂-injured cells by increasing the ratio of cells in the S/G₂ phase. Furthermore, western blot analysis revealed that PI3K expression levels were markedly increased after 24 h, as a result of the GM1 treatment, while the expression of both GSK-3 markedly decreased. In addition, the ratio of nuclear-to-cytoplasmic NF-κB expression increased in the GM1-treated cells. In summary, GM1 exhibited marked protective effects on the HUVECs, possibly due to the ability of GM1 in maintaining the integrity of the endothelium and increasing the proportion of cells undergoing mitosis, a process in which the PI3K/GSK-3 and NF-κB pathways are crucially involved.

Energy metabolism disorders in rare and common diseases. Toward bioenergetic modulation therapy and the training of a new generation of European scientists

Energy metabolism alterations are found in a large number of rare and common diseases of genetic or environmental origin. The number of patients that could benefit from bioenergetic modulation therapy (BIOMET) is therefore very important and includes individuals with pathologies as diverse as mitochondrial diseases, acute coronary syndrome, chronic kidney disease, asthma or even cancer. Although, the alteration of energy metabolism is disease specific and sometimes patient specific, the strategies for BIOMET could be common and target a series of bioenergetic regulatory mechanisms discussed in this article. An excellent training of scientists in the field of energy metabolism, related human diseases and drug discovery is also crucial to form a young generation of MDs, PHDs and Pharma or CRO-group leaders who will discover novel personalized bioenergetic medicines, through pharmacology, genetics, nutrition or adapted exercise training. The Mitochondrial European Educational Training (MEET) consortium was created to pursue this goal, and we dedicated here a special issue of Organelle in Focus (OiF) to highlight their objectives. A total of 10 OiFs articles constitute this Directed Issue on Mitochondrial Medicine. As part of this editorial article, we asked timely questions to the PR. Jan W. Smeitink, professor of Mitochondrial Medicine and CEO of Khondrion, a mitochondrial medicine company. He shared with us his objectives and strategies for the study of mitochondrial diseases and the identification of future treatments. This article is part of a Directed Issue entitled: Energy Metabolism Disorders and Therapies.

Targeting mitochondria with methylene blue protects mice against acetaminophen-induced liver injury

Acetaminophen (APAP) overdose is a frequent cause of drug-induced liver injury and the most frequent cause of acute liver failure in the Western world. Previous studies with mouse models have revealed that impairment of mitochondrial respiration is an early event in the pathogenesis, but the exact mechanisms have remained unclear, and therapeutic approaches to specifically target mitochondria have been insufficiently explored. Here, we found that the reactive oxidative metabolite of APAP, N-acetyl-p-benzoquinoneimine (NAPQI), caused the selective inhibition of mitochondrial complex II activity by >90% in both mouse hepatic mitochondria and yeast-derived complexes reconstituted into nanoscale model membranes, as well as the decrease of succinate-driven adenosine triphosphate (ATP) biosynthesis rates. Based on these findings, we hypothesized that methylene blue (MB), a mitochondria-permeant redox-active compound that can act as an alternative electron carrier, protects against APAP-induced hepatocyte injury. We found that MB (<3 µM) readily accepted electrons from NAPQI-altered, succinate-energized complex II and transferred them to cytochrome c, restoring ATP biosynthesis rates. In cultured mouse hepatocytes, MB prevented the mitochondrial permeability transition and loss of intracellular ATP without interfering with APAP bioactivation. In male C57BL/6J mice treated with APAP (450 mg/kg, intraperitoneally [IP]), MB (10 mg/kg, IP, administered 90 minutes post-APAP) protected against hepatotoxicity, whereas mice treated with APAP alone developed massive centrilobular necrosis and increased serum alanine aminotransferase activity. APAP treatment inhibited complex II activity ex vivo, but did not alter the protein expression levels of subunits SdhA or SdhC after 4 hours.

CONCLUSION

MB can effectively protect mice against APAP-induced liver injury by bypassing the NAPQI-altered mitochondrial complex II, thus alleviating the cellular energy crisis. Because MB is a clinically used drug, its potential application after APAP overdose in patients should be further explored.