Necroptosis in global cerebral ischemia: a role for endoplasmic reticulum stress

Endoplasmic reticulum stress-mediated cell death in cardiovascular disease

The endoplasmic reticulum (ER) plays a vital function in maintaining cellular homeostasis. Endoplasmic reticulum stress (ERS) can trigger various modes of cell death by activating the unfolded protein response (UPR) signaling pathway. Cell death plays a crucial role in the occurrence and development of diseases such as cancer, liver diseases, neurological diseases, and cardiovascular diseases. Several cardiovascular diseases including hypertension, atherosclerosis, and heart failure are associated with ER stress. ER stress-mediated cell death is of interest in cardiovascular disease. Moreover, an increasing body of evidence supports the potential of modulating ERS for treating cardiovascular disease. This paper provides a comprehensive review of the UPR signaling pathway, the mechanisms that induce cell death, and the modes of cell death in cardiovascular diseases. Additionally, we discuss the mechanisms of ERS and UPR in common cardiovascular diseases, along with potential therapeutic strategies.

Nrf2: a dark horse in doxorubicin-induced cardiotoxicity

Being a broad-spectrum anticancer drug, doxorubicin is indispensable for clinical treatment. Unexpectedly, its cardiotoxic side effects have proven to be a formidable obstacle. Numerous studies are currently devoted to elucidating the pathological mechanisms underlying doxorubicin-induced cardiotoxicity. Nrf2 has always played a crucial role in oxidative stress, but numerous studies have demonstrated that it also plays a vital part in pathological mechanisms like cell death and inflammation. Numerous studies on the pathological mechanisms associated with doxorubicin-induced cardiotoxicity demonstrate this. Several clinical drugs, natural and synthetic compounds, as well as small molecule RNAs have been demonstrated to prevent doxorubicin-induced cardiotoxicity by activating Nrf2. Consequently, this study emphasizes the introduction of Nrf2, discusses the role of Nrf2 in doxorubicin-induced cardiotoxicity, and concludes with a summary of the therapeutic modalities targeting Nrf2 to ameliorate doxorubicin-induced cardiotoxicity, highlighting the potential value of Nrf2 in doxorubicin-induced cardiotoxicity.

Molecular mechanisms associated with the chemoprotective role of protocatechuic acid and its potential benefits in the amelioration of doxorubicin-induced cardiotoxicity: A review

Since its discovery in the 1960 s, doxorubicin (DOX) has constantly elicited the broadest spectrum of cancerocidal activity against human cancers. However, cardiotoxicity caused by DOX directly as well as its metabolites is a great source of concern over the continuous use of DOX in chemotherapy. While the exact mechanism of DOX-induced cardiotoxicity is yet to be completely understood, recent studies indicate oxidative stress, inflammation, and several forms of cell death as key pathogenic mechanisms that underpin the etiology of doxorubicin-induced cardiotoxicity (DIC). Notably, these key mechanistic events are believed to be negatively regulated by 3,4-dihydroxybenzoic acid or protocatechuic acid (PCA)-a plant-based phytochemical with proven anti-oxidant, anti-inflammatory, and anti-apoptotic properties. Here, we review the experimental findings detailing the potential ameliorative effects of PCA under exposure to DOX. We also discuss molecular insights into the pathophysiology of DIC, highlighting the potential intervention points where the use of PCA as a veritable chemoprotective agent may ameliorate DOX-induced cardiotoxicities as well as toxicities due to other anticancer drugs like cisplatin. While we acknowledge that controlled oral administration of PCA during chemotherapy may be insufficient to eliminate all toxicities due to DOX treatment, we propose that the ability of PCA to block oxidative stress, attenuate inflammation, and abrogate several forms of cardiomyocyte cell death underlines its great promise in the amelioration of DIC.

Molecular insights into the pathophysiology of doxorubicin-induced cardiotoxicity: a graphical representation

A breakthrough in oncology research was the discovery of doxorubicin (Dox) in the 1960's. Unlike other chemotherapy drugs, Dox was determined to have a greater therapeutic index. Since its discovery, Dox has, in part, contributed to the 5-10-year survival increase in cancer patient outcomes. Unfortunately, despite its efficacy, both in adult and pediatric cancers, the clinical significance of Dox is tainted by its adverse side effects, which usually manifest as cardiotoxicity. The issue stems from Dox's lack of specificity which prevents it from accurately distinguishing between cancer cells and healthy cell lines, like cardiomyocytes. In addition, the high binding affinity of Dox to topoisomerases, which are abundantly found in cancer and cardiac cells in different isoforms, potentiates DNA damage. In both cell lines, Dox induces cytotoxicity by stimulating the production of pro-oxidants whilst inhibiting antioxidant enzymatic activity. Given that the cardiac muscle has an inherently low antioxidant capacity makes it susceptible to oxidative damage thereby, allowing the accumulation of Dox within the myocardium. Subsequently, Dox drives the activation of cell death pathways, such as ferroptosis, necroptosis and apoptosis by triggering numerous cellular responses that have been implicated in diseases. To date, the exact mechanism by which Dox induces the cardiotoxicity remains an aspect of much interest in cardio-oncology research. Hence, the current review summarizes the proposed mechanisms that are associated with the onset and progression of DIC.

Hypothermia selectively protects the anterior forebrain mesocircuit during global cerebral ischemia

Hypothermia is an important protective strategy against global cerebral ischemia following cardiac arrest. However, the mechanisms of hypothermia underlying the changes in different regions and connections of the brain have not been fully elucidated. This study aims to identify the metabolic nodes and connection integrity of specific brain regions in rats with global cerebral ischemia that are most affected by hypothermia treatment. ¹⁸F-fluorodeoxyglucose positron emission tomography was used to quantitatively determine glucose metabolism in different brain regions in a rat model of global cerebral ischemia established at 31–33°C. Diffusion tensor imaging was also used to reconstruct and explore the brain connections involved. The results showed that, compared with the model rats established at 37–37.5°C, the rat models of global cerebral ischemia established at 31–33°C had smaller hypometabolic regions in the thalamus and primary sensory areas and sustained no obvious thalamic injury. Hypothermia selectively preserved the integrity of the anterior forebrain mesocircuit, exhibiting protective effects on the brain during the global cerebral ischemia. The study was approved by the Institutional Animal Care and Use Committee at Capital Medical University (approval No. XW-AD318-97-019) on December 15, 2019.

Targeting Programmed Cell Death to Improve Stem Cell Therapy: Implications for Treating Diabetes and Diabetes-Related Diseases

Stem cell therapies have shown promising therapeutic effects in restoring damaged tissue and promoting functional repair in a wide range of human diseases. Generations of insulin-producing cells and pancreatic progenitors from stem cells are potential therapeutic methods for treating diabetes and diabetes-related diseases. However, accumulated evidence has demonstrated that multiple types of programmed cell death (PCD) existed in stem cells post-transplantation and compromise their therapeutic efficiency, including apoptosis, autophagy, necroptosis, pyroptosis, and ferroptosis. Understanding the molecular mechanisms in PCD during stem cell transplantation and targeting cell death signaling pathways are vital to successful stem cell therapies. In this review, we highlight the research advances in PCD mechanisms that guide the development of multiple strategies to prevent the loss of stem cells and discuss promising implications for improving stem cell therapy in diabetes and diabetes-related diseases.

The Role of HSP90α in Methamphetamine/Hyperthermia-Induced Necroptosis in Rat Striatal Neurons

Methamphetamine (METH) is one of the most widely abused synthetic drugs in the world. The users generally present hyperthermia (HT) and psychiatric symptoms. However, the mechanisms involved in METH/HT-induced neurotoxicity remain elusive. Here, we investigated the role of heat shock protein 90 alpha (HSP90α) in METH/HT (39.5°C)-induced necroptosis in rat striatal neurons and an in vivo rat model. METH treatment increased core body temperature and up-regulated LDH activity and the molecular expression of canonical necroptotic factors in the striatum of rats. METH and HT can induce necroptosis in primary cultures of striatal neurons. The expression of HSP90α increased following METH/HT injuries. The specific inhibitor of HSP90α, geldanamycin (GA), and HSP90α shRNA attenuated the METH/HT-induced upregulation of receptor-interacting protein 3 (RIP3), phosphorylated RIP3, mixed lineage kinase domain-like protein (MLKL), and phosphorylated MLKL. The inhibition of HSP90α protected the primary cultures of striatal neurons from METH/HT-induced necroptosis. In conclusion, HSP90α plays an important role in METH/HT-induced neuronal necroptosis and the HSP90α-RIP3 pathway is a promising therapeutic target for METH/HT-induced neurotoxicity in the striatum.

Targeting the gasdermin D as a strategy for ischemic stroke therapy

Stroke is a major cause of death and disability worldwide that triggers a variety of neuropathological conditions, leading to the initiation of several pro-inflammatory mediators and neuronal damage. Neuroinflammation has been considered the potential therapeutic target and contributes to the pathology of ischemia and reperfusion. Pyroptosis is an inflammatory form of programmed cell death that plays an important role in immune protection against stroke. Gasdermin D (GSDMD) is the final executor of pyroptosis upon cleavage by caspases-1/4/5/11, followed by canonical and noncanonical inflammasome activation, leading to a series of inflammatory responses. GSDMD N-terminal domain assembles plasma membrane as well as organelle membrane pores to induce cytolysis, thereby triggering cytokine release and inflammatory-related cell death. In our review, we concisely summarized and highlighted the potential role of GSDMD-regulated pyroptosis and the biological characteristic of GSDMD as a therapeutic target in ischemic stroke. A better understanding of the roles of GSDMD may provide a theoretical basis for the design of novel therapeutic interventions for the treatment of ischemic stroke.

[Protective effect of iridoid glycosides of radix scrophulariae on endoplasmic reticulum stress induced by oxygen-glucose deprivation and reperfusion in vitro model]

OBJECTIVE

To investigate the regulatory effect of iridoid glycoside of radix scrophulariae (IGRS) on endoplasmic reticulum stress induced by oxygen-glucose deprivation and reperfusion in vitro model.

METHODS

Rat pheochromocytoma PC12 cells were pretreated with IGRS (50, 100, 200 μg/mL) for 24h, and the in vitro model of oxygen-glucose deprivation/reoxygenation (OGD/R) was applied. The cell viability was determined by MTT and lactate dehydrogenase (LDH) assay. The apoptotic rate was detected by flow cytometry. The expression of B-cell lymphoma-2 (Bcl-2), Bcl-2 related X protein (Bax), C/EBP homologous protein (CHOP), caspase-12 protein, and glucose-regulated protein-78(GRP78)were detected by Western blotting. The mRNA expression levels of sarco/endoplasmic reticulum Ca2+-ATPase2 (SERCA2), 1, 4, 5-triphosphate inositol receptor 1 (IP3R1), and ryanodine receptor 2 (RyR2)were detected by real-time RT-PCR. Free Ca2+ concentration [Ca2+]i was determined by using laser scanning confocal microscopy.

RESULTS

The damage caused by OGD/R to PC12 cells was significantly reduced by IGRS, with significant effect on increasing survival rate and reducing LDH release (all P<0.01). The expression of GRP78, CHOP, Bax, and caspase-12 were down-regulated (all P<0.01), and the expression of Bcl-2 and Bcl-2/Bax ratio was up-regulated (all P<0.01); IGRS increased the expression of SERCA2 mRNA in PC12 cells after OGD/R injury (P<0.01), decreased [Ca2+]i and down-regulated the expression of RyR2 mRNA and IP3R1 mRNA.

CONCLUSIONS

IGRS has neuroprotective effect, which may alleviate cerebral ischemia-reperfusion injury by regulating SERCA2, maintaining calcium balance, and inhibiting endoplasmic reticulum stress-mediated apoptosis.