Ibudilast attenuates doxorubicin-induced cytotoxicity by suppressing formation of TRPC3 channel and NADPH oxidase 2 protein complexes

TRP channels in cardiac mechano-redox coupling and diseases

Reactive oxygen species (ROS) produced by mechanically stretching cardiomyocytes is a crucial mediator to increase contractile force in accordance with the Frank-Starling law. However, excessive ROS production leads to oxidative stress, contributing to myocardial atrophic remodeling and cellular damage. NADPH oxidase, the primary enzyme responsible for ROS production localized on the plasma membrane and organelle membranes, plays a key role in membrane-oriented ROS signaling. Two isoforms of NADPH oxidase, Nox2 (constitutive) and Nox4 (inducible), are predominantly expressed in cardiomyocytes, each playing unique roles in different contexts. Recent studies have revealed that Nox proteins form protein signaling complexes with transient receptor potential (TRP) channel proteins, amplifying ROS signaling in hearts. This review presents the putative mechanism of protein-protein interaction between TRP and Nox and their pathophysiological significance in hearts and discusses therapeutic strategies targeting TRP-Nox protein interactions for the treatment of heart failure.

Transient receptor potential channels in viral infectious diseases: Biological characteristics and regulatory mechanisms

BACKGROUND

Viral infectious diseases have long posed a challenge to humanity. In recent decades, transient receptor potential (TRP) channels have emerged as newly investigated cation channels. Increasing evidence suggests that TRP channel-mediated Ca2+ homeostasis disruptions, along with associated pathological changes, are critical factors in the onset and progression of viral infectious diseases. However, the precise roles and mechanisms of TRP channels in these diseases remain to be systematically elucidated.

AIM OF REVIEW

The aim of this review is to systematically summarize recent advances in understanding TRP channels in viral infections, and based on current progress and challenges, propose future directions for research.

KEY SCIENTIFIC CONCEPTS OF REVIEW

This review summarizes the classification and biological functions of the TRP family, explores the mechanisms by which TRP channels contribute to viral infections, and highlights specific mechanisms at three levels: virus, host, and outcome. These include the direct role in viral biology and replication, the indirect role in host immunity and inflammation, and the resulting pathological changes. Additionally, we discuss the potential applications of the TRP family in the treatment of viral infectious diseases and propose future research directions.

Inhibition of dynamin-related protein 1-filamin interaction improves systemic glucose metabolism

BACKGROUND AND PURPOSE

Maintaining mitochondrial quality is attracting attention as a new strategy to treat diabetes and diabetic complications. We previously reported that mitochondrial hyperfission by forming a protein complex between dynamin-related protein (Drp) 1 and filamin, mediates chronic heart failure and cilnidipine, initially developed as an L/N-type Ca2+ channel blocker, improves heart failure by inhibiting Drp1-filamin protein complex. We investigated whether cilnidipine improves hyperglycaemia of various diabetic mice models.

EXPERIMENTAL APPROACH

Retrospective analysis focusing on haemoglobin A1c (HbA1c) was performed in hypertensive and hyperglycaemic patients taking cilnidipine and amlodipine. After developing diabetic mice by streptozotocin (STZ) treatment, an osmotic pump including drug was implanted intraperitoneally, followed by weekly measurements of blood glucose levels. Mitochondrial morphology was analysed by electron microscopy. A Ca2+ channel-insensitive cilnidipine derivative (1,4-dihydropyridine [DHP]) was synthesized and its pharmacological effect was evaluated using obese (ob/ob) mice fed with high-fat diet (HFD).

KEY RESULTS

In patients, cilnidipine was superior to amlodipine in HbA1c lowering effect. Cilnidipine treatment improved systemic hyperglycaemia and mitochondrial morphological abnormalities in STZ-exposed mice, without lowering blood pressure. Cilnidipine failed to improve hyperglycaemia of ob/ob mice, with suppressing insulin secretion. 1,4-DHP improved hyperglycaemia and mitochondria abnormality in ob/ob mice fed HFD. 1,4-DHP and cilnidipine improved basal oxygen consumption rate of HepG2 cells cultured under 25 mM glucose.

CONCLUSION AND IMPLICATIONS

Inhibition of Drp1-filamin protein complex formation becomes a new strategy for type 2 diabetes treatment.

Cardiotoxicity in Cancer Patients: The Prevalence, Risk Factors, and Cardioprotective Measures in a Cancer Centre in Saudi Arabia

BACKGROUND

Chemotherapy-related cardiotoxicity can exhibit several patterns of functional, structural, and vascular complications. This study aims to identify the patterns and the factors associated with cardiotoxicity in cancer patients.

METHOD

A retrospective cross-sectional analysis of 96 adult cancer patients undergoing anticancer therapy was investigated at King Khalid Hospital in Najran, Saudi Arabia, from May 2022 to April 2023. The data on patient and cancer characteristics, treatment, and outcomes were collected and analyzed. Factors associated with cardiotoxicity were investigated through univariate analyses using odds ratio (OR) and 95% confidence interval (CI).

RESULTS

 Among the 96 cancer patients in the study, cardiotoxicity occurred in 12 individuals (12.5%). The mean age was 57.0 ± 13.3 years (range: 32-81 years), with 32 (33.3%) being above 65 years. The most common comorbidities were diabetes (n=48; 50%), followed by hypertension (n=32; 33.3%), and dyslipidemia (n=20; 20.8%). The most common cancers were gastrointestinal cancer (n=32; 33.3%), followed by breast cancer (n=22; 22.9%) and lymphoma (n=14; 14.6%). Females were disproportionately affected (64.6%), with 57.3% of them in the metastatic stage. The majority of patients (90.6%) had normal ejection fraction before chemotherapy initiation. In univariate analysis, current smoking (OR: 7.00; 95%CI: 1.94-25.25, p= 0.003), history of percutaneous cardiac intervention (OR: 40.24; 95%CI: 1.80-896.26, p= 0.019), diabetes (OR: 6.05; 95%CI: 1.24-29.32, p= 0.025), renal failure (OR: 8.20; 95%CI: 0.91-74.88, p= 0.046), dyslipidemia (OR: 5.00; 95 CI: 1.38-18.32, p=0.012), anthracycline use (OR: 18.33; 95%CI: 4.36-126.55, p <0.001), trastuzumab use (OR: 25.00; 95%CI: 6.25-129.86, p < 0.001), and increased chemotherapy cycles number (> 10 cycles) (OR: 73.00; 95%CI: 8.56- 622.36, p < 0.001) were associated with cardiotoxicity. Additionally, beta-blocker use was associated with lower rates of cardiotoxicity (OR: 0.17; 95%CI: 0.036-0.84, p= 0.029).

CONCLUSIONS

The incidence of cardiotoxicity among cancer patients treated with chemotherapy is modest, difficult to predict, and independent of baseline cardiac systolic functions. Factors associated with cardiotoxicity include smoking, history of percutaneous cardiac intervention, diabetes, renal failure, dyslipidemia, anthracycline or trastuzumab use, and increased chemotherapy cycle numbers. A combination of various anticancer drugs and chemotherapy may dramatically raise the risk of cardiotoxicity in cancer patients. As a result, patients receiving high-risk cardiotoxic drugs should be monitored with caution to avoid drug-related cardiotoxicity. Furthermore, proactive treatment techniques aiming at reducing the possible cardiotoxic effects of anticancer therapy are critical.

TRP Channels in Tumoral Processes Mediated by Oxidative Stress and Inflammation

The channels from the superfamily of transient receptor potential (TRP) activated by reactive oxygen species (ROS) can be defined as redox channels. Those with the best exposure of the cysteine residues and, hence, the most sensitive to oxidative stress are TRPC4, TRPC5, TRPV1, TRPV4, and TRPA1, while others, such as TRPC3, TRPM2, and TRPM7, are indirectly activated by ROS. Furthermore, activation by ROS has different effects on the tumorigenic process: some TRP channels may, upon activation, stimulate proliferation, apoptosis, or migration of cancer cells, while others inhibit these processes, depending on the cancer type, tumoral microenvironment, and, finally, on the methods used for evaluation. Therefore, using these polymodal proteins as therapeutic targets is still an unmet need, despite their draggability and modulation by simple and mostly unharmful compounds. This review intended to create some cellular models of the interaction between oxidative stress, TRP channels, and inflammation. Although somewhat crosstalk between the three actors was rather theoretical, we intended to gather the recently published data and proposed pathways of cancer inhibition using modulators of TRP proteins, hoping that the experimental data corroborated clinical information may finally bring the results from the bench to the bedside.

Function of TRP channels in monocytes/macrophages

The transient receptor potential channel (TRP channel) family is a kind of non- specific cation channel widely distributed in various tissues and organs of the human body, including the respiratory system, cardiovascular system, immune system, etc. It has been reported that various TRP channels are expressed in mammalian macrophages. TRP channels may be involved in various signaling pathways in the development of various systemic diseases through changes in intracellular concentrations of cations such as calcium and magnesium. These TRP channels may also intermingle with macrophage activation signals to jointly regulate the occurrence and development of diseases. Here, we summarize recent findings on the expression and function of TRP channels in macrophages and discuss their role as modulators of macrophage activation and function. As research on TRP channels in health and disease progresses, it is anticipated that positive or negative modulators of TRP channels for treating specific diseases may be promising therapeutic options for the prevention and/or treatment of disease.

The Pleiotropic Role of Extracellular ATP in Myocardial Remodelling

Myocardial remodelling is a molecular, cellular, and interstitial adaptation of the heart in response to altered environmental demands. The heart undergoes reversible physiological remodelling in response to changes in mechanical loading or irreversible pathological remodelling induced by neurohumoral factors and chronic stress, leading to heart failure. Adenosine triphosphate (ATP) is one of the potent mediators in cardiovascular signalling that act on the ligand-gated (P2X) and G-protein-coupled (P2Y) purinoceptors via the autocrine or paracrine manners. These activations mediate numerous intracellular communications by modulating the production of other messengers, including calcium, growth factors, cytokines, and nitric oxide. ATP is known to play a pleiotropic role in cardiovascular pathophysiology, making it a reliable biomarker for cardiac protection. This review outlines the sources of ATP released under physiological and pathological stress and its cell-specific mechanism of action. We further highlight a series of cardiovascular cell-to-cell communications of extracellular ATP signalling cascades in cardiac remodelling, which can be seen in hypertension, ischemia/reperfusion injury, fibrosis, hypertrophy, and atrophy. Finally, we summarize current pharmacological intervention using the ATP network as a target for cardiac protection. A better understanding of ATP communication in myocardial remodelling could be worthwhile for future drug development and repurposing and the management of cardiovascular diseases.

Knockout of Purinergic P2Y6 Receptor Fails to Improve Liver Injury and Inflammation in Non-Alcoholic Steatohepatitis

Nonalcoholic steatohepatitis (NASH) is a disease that progresses from nonalcoholic fatty liver (NAFL) and which is characterized by inflammation and fibrosis. The purinergic P2Y₆ receptor (P2Y₆R) is a pro-inflammatory G_q/G₁₂ family protein-coupled receptor and reportedly contributes to intestinal inflammation and cardiovascular fibrosis, but its role in liver pathogenesis is unknown. Human genomics data analysis revealed that the liver P2Y₆R mRNA expression level is increased during the progression from NAFL to NASH, which positively correlates with inductions of C-C motif chemokine 2 (CCL2) and collagen type I α1 chain (Col1a1) mRNAs. Therefore, we examined the impact of P2Y₆R functional deficiency in mice crossed with a NASH model using a choline-deficient, L-amino acid-defined, high-fat diet (CDAHFD). Feeding CDAHFD for 6 weeks markedly increased P2Y₆R expression level in mouse liver, which was positively correlated with CCL2 mRNA induction. Unexpectedly, the CDAHFD treatment for 6 weeks increased liver weights with severe steatosis in both wild-type (WT) and P2Y₆R knockout (KO) mice, while the disease marker levels such as serum AST and liver CCL2 mRNA in CDAHFD-treated P2Y₆R KO mice were rather aggravated compared with those of CDAHFD-treated WT mice. Thus, P2Y₆R may not contribute to the progression of liver injury, despite increased expression in NASH liver.

Targeting Mitochondria and Oxidative Stress in Cancer- and Chemotherapy-Induced Muscle Wasting

Significance: Cancer is frequently associated with the early appearance of cachexia, a multifactorial wasting syndrome. If not present at diagnosis, cachexia develops either as a result of tumor progression or as a side effect of anticancer treatments, especially of standard chemotherapy, eventually representing the direct cause of death in up to one-third of all cancer patients. Cachexia, within its multiorgan affection, is characterized by severe loss of muscle mass and function, representing the most relevant subject of preclinical and clinical investigation. Recent Advances: The pathogenesis of muscle wasting in cancer- and chemotherapy-induced cachexia is complex, and encompasses heightened protein catabolism and reduced anabolism, disrupted mitochondria and energy metabolism, and even neuromuscular junction dismantling. The mechanisms underlying these alterations are still controversial, especially concerning the molecular drivers that could be targeted for anticachexia therapies. Inflammation and mitochondrial oxidative stress are among the principal candidates; the latter being extensively discussed in the present review. Critical Issues: Several approaches have been tested to modulate the redox homeostasis in tumor hosts, and to counteract cancer- and chemotherapy-induced muscle wasting, from exercise training to distinct classes of direct or indirect antioxidants. We herein report the most relevant results obtained from both preclinical and clinical trials. Future Directions: Including the assessment and the treatment of altered redox balance in the clinical management of cancer patients is still a big challenge. The available evidence suggests that fortifying the antioxidant defenses by either pharmacological or nonpharmacological strategies will likely improve cachexia and eventually the outcome of a broad cancer patient population. Antioxid. Redox Signal. 38, 352-370.

Risk factors from Framingham risk score for anthracyclines cardiotoxicity in breast cancer: A systematic review and meta-analysis

Background

Framingham risk score (FRS) is an effective tool for evaluating the 10-year risk of cardiovascular diseases. However, the sensitivity of FRS for anthracycline-induced cardiotoxicity is unclear. This meta-analysis aims to evaluate the correlation between risk factors (hypertension, hyperlipidemia, diabetes, smoking, and obesity) in FRS and anthracycline-induced cardiotoxicity in breast cancer.

Methods

We searched PubMed, EMBASE, and Cochrane Library for studies published from inception to January 2022 which reported cardiotoxicity due to anthracycline. Cardiotoxicity defined as any cardiac events were used as the primary endpoint. A total of 33 studies involving 55,708 breast cancer patients treated with anthracyclines were included in this meta-analysis.

Results

At least one risk factor was identified at baseline for the 55,708 breast cancer patients treated with anthracycline. Hypertension [I 2 = 45%, Fixed, RR (95% CI) = 1.40 (1.22, 1.60), p < 0.00001], hyperlipidemia [I 2 = 0%, Fixed, RR (95% CI): 1.35 (1.12, 1.62), p = 0.002], diabetes [I 2 = 0%, Fixed, RR (95% CI): 1.29 (1.05, 1.57), p = 0.01], and obesity [I 2 = 0%, Fixed, RR (95% CI): 1.32 (1.05, 1.67), p = 0.02] were associated with increased risks of cardiac events. In addition, smoking was also associated with reduced left ventricular ejection fraction (LVEF) during anthracycline chemotherapy [I 2 = 0%, Fixed, OR (95% CI): 1.91 (1.24, 2.95), p = 0.003] in studies that recorded only the odds ratio (OR).

Conclusion

Hypertension, hyperlipidemia, diabetes, smoking, and obesity are associated with increased risks of anthracycline-induced cardiotoxicity. Therefore, corresponding measures should be used to manage cardiovascular risk factors in breast cancer during and after anthracycline treatment.

Clenbuterol Prevents Mechanical Unloading-Induced Myocardial Atrophy via Upregulation of Transient Receptor Potential Channel-3

Left ventricular assist device in combination with clenbuterol has been demonstrated to significantly improve heart function in patients with advanced heart failure. However, the roles of clenbuterol in mechanical unloading and its underlying mechanism are poorly understood. A rat abdominal heart transplantation model has been developed to mimic mechanical unloading of the heart. The recipient rats were randomly segregated into experimental groups for the daily administration of either saline (the "Trans" group; n = 13) or clenbuterol (2 mg/kg, the "Trans + CB" group; n = 12). Another group of 10 rats served as a treatment mimic control/sham animals (the "Sham" group). All interventions were performed via intraperitoneal injections once daily for 4 weeks. The Trans group animals exhibited myocardial atrophy and dysfunction with decreased expression levels of transient receptor potential channel 3 (TRPC3) and phospholipase C-β1 (PLC-β1) at 4 weeks post-transplantation. Administration of clenbuterol improved cardiac function, prevented myocardial atrophy, and restored expression of TRPC3 and PLC-β1 in the unloaded hearts of the "Trans + CB" animals at 4 weeks post-transplantation. Silencing of the TRPC3 gene by siRNA inhibited the pro-hypertrophic effect of clenbuterol in the rat primary cardiomyocytes in vitro. Furthermore, U73122, an inhibitor of the PLC-β1/diacylglycerol (DAG) pathway, significantly attenuated clenbuterol-induced upregulation of TRPC3 in cardiomyocytes. These findings suggest that the anti-atrophic effect of clenbuterol may be dependent on the upregulation of TRPC3 through the activation of the PLC-β1/DAG pathway during mechanical unloading. The results of our study reveal a potential target for the prevention and treatment of mechanical unloading-induced myocardial atrophy.

TRPC3-Nox2 Protein Complex Formation Increases the Risk of SARS-CoV-2 Spike Protein-Induced Cardiomyocyte Dysfunction through ACE2 Upregulation

Myocardial damage caused by the newly emerged coronavirus (SARS-CoV-2) infection is one of the key determinants of COVID-19 severity and mortality. SARS-CoV-2 entry to host cells is initiated by binding with its receptor, angiotensin-converting enzyme (ACE) 2, and the ACE2 abundance is thought to reflect the susceptibility to infection. Here, we report that ibudilast, which we previously identified as a potent inhibitor of protein complex between transient receptor potential canonical (TRPC) 3 and NADPH oxidase (Nox) 2, attenuates the SARS-CoV-2 spike glycoprotein pseudovirus-evoked contractile and metabolic dysfunctions of neonatal rat cardiomyocytes (NRCMs). Epidemiologically reported risk factors of severe COVID-19, including cigarette sidestream smoke (CSS) and anti-cancer drug treatment, commonly upregulate ACE2 expression level, and these were suppressed by inhibiting TRPC3-Nox2 complex formation. Exposure of NRCMs to SARS-CoV-2 pseudovirus, as well as CSS and doxorubicin (Dox), induces ATP release through pannexin-1 hemi-channels, and this ATP release potentiates pseudovirus entry to NRCMs and human iPS cell-derived cardiomyocytes (hiPS-CMs). As the pseudovirus entry followed by production of reactive oxygen species was attenuated by inhibiting TRPC3-Nox2 complex in hiPS-CMs, we suggest that TRPC3-Nox2 complex formation triggered by panexin1-mediated ATP release participates in exacerbation of myocardial damage by amplifying ACE2-dependent SARS-CoV-2 entry.

Does Myocardial Atrophy Represent Anti-Arrhythmic Phenotype?

This review focuses on cardiac atrophy resulting from mechanical or metabolic unloading due to various conditions, describing some mechanisms and discussing possible strategies or interventions to prevent, attenuate or reverse myocardial atrophy. An improved awareness of these conditions and an increased focus on the identification of mechanisms and therapeutic targets may facilitate the development of the effective treatment or reversion for cardiac atrophy. It appears that a decrement in the left ventricular mass itself may be the central component in cardiac deconditioning, which avoids the occurrence of life-threatening arrhythmias. The depressed myocardial contractility of atrophied myocardium along with the upregulation of electrical coupling protein, connexin43, the maintenance of its topology, and enhanced PKCƐ signalling may be involved in the anti-arrhythmic phenotype. Meanwhile, persistent myocardial atrophy accompanied by oxidative stress and inflammation, as well as extracellular matrix fibrosis, may lead to severe cardiac dysfunction, and heart failure. Data in the literature suggest that the prevention of heart failure via the attenuation or reversion of myocardial atrophy is possible, although this requires further research.

Drug repurposing for the treatment of COVID-19

Coronavirus disease 2019 (COVID-19) remains prevalent worldwide since its onset was confirmed in Wuhan, China in 2019. Vaccines against the causative virus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), have shown a preventive effect against the onset and severity of COVID-19, and social and economic activities are gradually recovering. However, the presence of vaccine-resistant variants has been reported, and the development of therapeutic agents for patients with severe COVID-19 and related sequelae remains urgent. Drug repurposing, also called drug repositioning or eco-pharma, is the strategy of using previously approved and safe drugs for a therapeutic indication that is different from their original indication. The risk of severe COVID-19 and mortality increases with advancing age, cardiovascular disease, hypertension, diabetes, and cancer. We have reported three protein-protein interactions that are related to heart failure, and recently identified that one mechanism increases the risk of SARS-CoV-2 infection in mammalian cells. This review outlines the global efforts and outcomes of drug repurposing research for the treatment of severe COVID-19. It also discusses our recent finding of a new protein-protein interaction that is common to COVID-19 aggravation and heart failure.

Cardiomyocyte Atrophy, an Underestimated Contributor in Doxorubicin-Induced Cardiotoxicity

Left ventricular (LV) mass loss is prevalent in doxorubicin (DOX)-induced cardiotoxicity and is responsible for the progressive decline of cardiac function. Comparing with the well-studied role of cell death, the part of cardiomyocyte atrophy (CMA) playing in the LV mass loss is underestimated and the knowledge of the underlying mechanism is still limited. In this review, we summarized the recent advances in the DOX-induced CMA. We found that the CMA caused by DOX is associated with the upregulation of FOXOs and “atrogenes,” the activation of transient receptor potential canonical 3-NADPH oxidase 2 (TRPC3-Nox2) axis, and the suppression of IGF-1-PI3K signaling pathway. The imbalance of anabolic and catabolic process may be the common final pathway of these mechanisms. At last, we provided some strategies that have been demonstrated to alleviate the DOX-induced CMA in animal models.

Redox-dependent internalization of the purinergic P2Y6 receptor limits colitis progression

[Figure: see text].

[Eco-pharma research aimed at developing COVID-19 therapeutic agent]

Novel coronavirus infection disease 2019 (COVID-19) is an emerging infectious disease that has been rampant worldwide since its onset was confirmed in Wuhan, China in 2019. An effective therapy has not yet been established, and there is an urgent need to establish a breakthrough therapeutic strategy for the prevention and treatment of COVID-19 aggravation. The main route of infection is that the Spike protein (S protein) on the surface of SARS-CoV-2 binds to its recognition receptor, angiotensin converting enzyme (ACE) 2, on the host cell surface. Then, SARS-CoV-2 invades the cell via endocytosis-dependent pathway. Although the major symptom of COVID-19 is lung inflammation, ACE2 is expressed not only in the lungs but also in various tissues including heart and digestive organs. We focused on the molecular mechanism underlying the development of heart failure, a pathology involved in COVID-19 aggravation risk factors and COVID-19 squeals. We revealed that cardiac ACE2 receptors were upregulated by exposure to various environmental stresses reported as COVID-19 aggravation risk factors, and the formation of membrane protein complex between TRPC3 and NADPH oxidase (Nox) 2 that participates in myocardial remodeling underlies pathological ACE2 upregulation. Furthermore, we utilized the already approved drugs that inhibit TRPC3-Nox2 protein complex formation, and identified that clomipramine, a tricyclic antidepressant, has the best potency to suppress ACE2 internalization induced by S protein exposure. This review introduces the mechanism of pathological ACE2 receptor upregulation through TRPC3-Nox2 complex formation in the heart, and the identification of a breakthrough drug candidate using in vitro pseudo-infection screening system.

Molecular mechanisms of anthracycline cardiovascular toxicity

Anthracyclines are effective chemotherapeutic agents, commonly used in the treatment of a variety of hematologic malignancies and solid tumors. However, their use is associated with a significant risk of cardiovascular toxicities and may result in cardiomyopathy and heart failure. Cardiomyocyte toxicity occurs via multiple molecular mechanisms, including topoisomerase II-mediated DNA double-strand breaks and reactive oxygen species (ROS) formation via effects on the mitochondrial electron transport chain, NADPH oxidases (NOXs), and nitric oxide synthases (NOSs). Excess ROS may cause mitochondrial dysfunction, endoplasmic reticulum stress, calcium release, and DNA damage, which may result in cardiomyocyte dysfunction or cell death. These pathophysiologic mechanisms cause tissue-level manifestations, including characteristic histopathologic changes (myocyte vacuolization, myofibrillar loss, and cell death), atrophy and fibrosis, and organ-level manifestations including cardiac contractile dysfunction and vascular dysfunction. In addition, these mechanisms are relevant to current and emerging strategies to diagnose, prevent, and treat anthracycline-induced cardiomyopathy. This review details the established and emerging data regarding the molecular mechanisms of anthracycline-induced cardiovascular toxicity.

Deletion of TRPC3 or TRPC6 Fails to Attenuate the Formation of Inflammation and Fibrosis in Non-alcoholic Steatohepatitis

Non-alcoholic steatohepatitis (NASH) is a disease that has progressed from non-alcoholic fatty liver disease (NAFLD) and is characterized by inflammation and fibrosis. Two transient receptor potential canonical (TRPC) subfamily members, TRPC3 and TRPC6 (TRPC3/6), reportedly participate in the development of fibrosis in cardiovascular and renal systems. We hypothesized that TRPC3/6 may also participate in NASH fibrosis. We evaluated the effects of TRPC3 or TRPC6 functional deficiency in a NASH mouse model using choline-deficient, L-amino acid-defined, high-fat diet (CDAHFD). Wild-type (WT) and TRPC3 or TRPC6 gene-deficient (KO) mice were fed with CDAHFD or standard diet for 6 weeks. The CDAHFD-induced body weight loss in TRPC6 KO mice was significantly lower compared with WT mice with CDAHFD. CDAHFD treatment significantly increased TRPC3 mRNA expression level and tissue weight in WT liver, which were suppressed in TRPC3 KO mice. However, either systemic deletion of TRPC3 or TRPC6 failed to attenuate liver steatosis, inflammation and fibrosis. These results imply that TRPC3 and TRPC6 are unlikely to be involved in liver dysfunction and fibrosis of NASH model mice.

Ibudilast, a Phosphodiesterase Inhibitor and Toll-Like Receptor-4 Antagonist, Improves Hemorrhagic Shock and Reperfusion-Induced Left Ventricular Dysfunction by Reducing Myocardial Tumor Necrosis Factor α

OBJECTIVES

Rapid loss of blood volume causes ischemic injury to myocardial cells and impairs cardiac function. Subsequent reperfusion, although necessary to revitalize stunned tissues, can induce production of reactive oxygen species and inflammation, causing further tissue damages and weakening cardiac function. Ibudilast, a Toll-like receptor-4 (TLR4) antagonist and an inhibitor of phosphodiesterase-4, possesses antioxidative and anti-inflammatory capacities. In this study, we aim to examine the protective efficacy of ibudilast against hemorrhagic shock and reperfusion (HSR)-induced myocardial injury and cardiac dysfunction.

METHODS

Studies were conducted on male Sprague-Dawley rats in 3 groups: sham-operated, HSR with, and HSR without pretreatment of ibudilast. Hemorrhagic shock was induced by withdrawing blood from the femoral artery until the mean aortic pressure dropped to around 40 mm Hg; reperfusion was conducted by replenishing blood after 120 minutes of hemorrhagic shock, and the observation continued for another 240 minutes. The left ventricular (LV) contractility, diastolic suction capacity, and ventricular stiffness were evaluated using simultaneous LV pressure, and volume was recorded during a temporary inferior vena cava constriction at the end of reperfusion. Ibudilast (10 mg/kg) was administered intraperitoneally 3 days and 20 minutes prior to HSR. Serum creatine kinase myocardial band (CK-MB) was examined at the end of both HSR, and serum CK-MB, myocardial TLR4 protein expression, and malondialdehyde (MDA) and tumor necrosis factor (TNF)-α levels at the end of reperfusion.

RESULTS

HSR induced an increase in serum CK-MB. Subsequent reperfusion further increased serum CK-MB, upregulated myocardial TLR4 protein expression, and increased tissue levels MDA and TNF-α vs the sham (P < .05). HSR reduced LV contractility, prolonged LV relaxation time, and increased LV diastolic stiffness. Ibudilast pretreatment attenuated HSR-induced TLR4 protein expression, reduced myocardial MDA and TNF-α levels, and protected against cardiac dysfunction.

CONCLUSIONS

Ibudilast pretreatment reduced myocardial TLR4 expression, decreased MDA and TNF-α levels, and protected against HSR-induced decrease in LV contractility, prolonged LV relaxation time, and increased diastolic stiffness.

Canonical Transient Receptor Potential Channels and Vascular Smooth Muscle Cell Plasticity

Vascular smooth muscle cells (VSMCs) play a pivotal role in the stability and tonic regulation of vascular homeostasis. VSMCs can switch back and forth between highly proliferative (synthetic) and fully differentiated (contractile) phenotypes in response to changes in the vessel environment. Abnormal phenotypic switching of VSMCs is a distinctive characteristic of vascular disorders, including atherosclerosis, pulmonary hypertension, stroke, and peripheral artery disease; however, how the control of VSMC phenotypic switching is dysregulated under pathological conditions remains obscure. Canonical transient receptor potential (TRPC) channels have attracted attention as a key regulator of pathological phenotype switching in VSMCs. Several TRPC subfamily member proteins—especially TRPC1 and TRPC6—are upregulated in pathological VSMCs, and pharmacological inhibition of TRPC channel activity has been reported to improve hypertensive vascular remodeling in rodents. This review summarizes the current understanding of the role of TRPC channels in cardiovascular plasticity, including our recent finding that TRPC6 participates in aberrant VSMC phenotype switching under ischemic conditions, and discusses the therapeutic potential of TRPC channels.

Untargeted Safety Pharmacology Screen of Blood-Activating and Stasis-Removing Patent Chinese Herbal Medicines Identified Nonherbal Ingredients as a Cause of Organ Damage in Experimental Models

Blood activation and stasis removal from circulation is a central principle for treatment of syndromes related to cerebral and cardiovascular diseases in Chinese herbal medicine. However, blood-activating and stasis-removing patent Chinese herbal medicine (BASR-pCHM) widely used with or without prescription in China and elsewhere are highly variable in composition and manufacture standard, making their safety assessment a challenging task. We proposed that an integrated evaluation of multiple toxicity parameters of BASR-pCHM would provide critical reference and guidelines for their safe clinical application. Examination of standardized extracts from 58 compound BASR-pCHM in vivo in VEGFR2-luc mice and in vitro in cardiac, renal, and hepatic cells identified Naoluotong capsule (NLTC) as a potent organ/cell damage inducer. Composition analysis revealed that NLTC was the one that contained nonherbal ingredients among the BASR-pCHM collection. In vivo and in vitro experiments confirmed that NLTC, as well as its chemical supplement tolperisone hydrochloride, caused organ and cell damage by reducing cell viability, mitochondrial mass/activity, while the NLTC herbal components did not. Taken together, our study showed that safety evaluation of patent herbal medicines already on market is still necessary and urgently needed. In addition, chemical/herbal interactions should be considered as an important contributor of potential toxicity when evaluating the safety of herbal medicine.

Ibudilast attenuates doxorubicin-induced cytotoxicity by suppressing formation of TRPC3 channel and NADPH oxidase 2 protein complexes

BACKGROUND AND PURPOSE

Doxorubicin is a highly effective anticancer agent but eventually induces cardiotoxicity associated with increased production of ROS. We previously reported that a pathological protein interaction between TRPC3 channels and NADPH oxidase 2 (Nox2) contributed to doxorubicin-induced cardiac atrophy in mice. Here we have investigated the effects of ibudilast, a drug already approved for clinical use and known to block doxorubicin-induced cytotoxicity, on the TRPC3-Nox2 complex. We specifically sought evidence that this drug attenuated doxorubicin-induced systemic tissue wasting in mice.

EXPERIMENTAL APPROACH

We used the RAW264.7 macrophage cell line to screen 1,271 clinically approved chemical compounds, evaluating functional interactions between TRPC3 channels and Nox2, by measuring Nox2 protein stability and ROS production, with and without exposure to doxorubicin. In male C57BL/6 mice, samples of cardiac and gastrocnemius muscle were taken and analysed with morphometric, immunohistochemical, RT-PCR and western blot methods. In the passive smoking model, cells were exposed to DMEM containing cigarette sidestream smoke.

KEY RESULTS

Ibudilast, an anti-asthmatic drug, attenuated ROS-mediated muscle toxicity induced by doxorubicin treatment or passive smoking, by inhibiting the functional interactions between TRPC3 channels and Nox2, without reducing TRPC3 channel activity.

CONCLUSIONS AND IMPLICATIONS

These results indicate a common mechanism underlying induction of systemic tissue wasting by doxorubicin. They also suggest that ibudilast could be repurposed to prevent muscle toxicity caused by anticancer drugs or passive smoking.