Pioglitazone Induces Cardiomyocyte Apoptosis and Inhibits Cardiomyocyte Hypertrophy Via VEGFR-2 Signaling Pathway

Cytotoxicity and toxicoproteomics analysis of thiazolidinedione exposure in human-derived cardiomyocytes

Thiazolidinediones (TZDs) (e.g. pioglitazone and rosiglitazone), known insulin sensitiser agents for type II diabetes mellitus, exhibit controversial effects on cardiac tissue. Despite consensus on their association with increased heart failure risk, limiting TZD use in diabetes management, the underlying mechanisms remain uncharacterised. Herein, we report a comprehensive in vitro investigation utilising a novel toxicoproteomics pipeline coupled with cytotoxicity assays in human adult cardiomyocytes to elucidate mechanistic insights into TZD cardiotoxicity. The cytotoxicity assay findings showed a significant loss of mitochondrial adenosine triphosphate production upon exposure to either TZD agents, which may underpin TZD cardiotoxicity. Our toxicoproteomics analysis revealed that mitochondrial dysfunction primarily stems from oxidative phosphorylation impairment, with distinct signalling mechanisms observed for both agents. The type of cell death differed strikingly between the two agents, with rosiglitazone exhibiting features of caspase-dependent apoptosis and pioglitazone implicating mitochondrial-mediated necroptosis, as evidenced by the protein upregulation in the phosphoglycerate mutase family 5-dynamin-related protein 1 axis. Furthermore, our analysis revealed additional mechanistic aspects of cardiotoxicity, showcasing drug specificity. The downregulation of various proteins involved in protein machinery and protein processing in the endoplasmic reticulum was observed in rosiglitazone-treated cells, implicating proteostasis in the rosiglitazone cardiotoxicity. Regarding pioglitazone, the findings suggested the potential activation of the interplay between the complement and coagulation systems and the disruption of the cytoskeletal architecture, which was primarily mediated through the integrin-signalling pathways responsible for pioglitazone-induced myocardial contractile failure. Collectively, this study unlocks substantial mechanistic insight into TZD cardiotoxicity, providing the rationale for future optimisation of antidiabetic therapies.

Amorfrutin B Compromises Hypoxia/Ischemia-induced Activation of Human Microglia in a PPARγ-dependent Manner: Effects on Inflammation, Proliferation Potential, and Mitochondrial Status

Amorfrutin B is a selective PPARγ modulator that we demonstrated to be a promising neuroprotective compound in cellular models of stroke and perinatal asphyxia. Although neuronal mechanisms of amorfrutin B-evoked neuroprotection have been identified, none of them reflects the actions of the compound on microglia, which play a pivotal role in brain response to hypoxia/ischemia. Here, we provide evidence for amorfrutin B-induced effects on human microglia subjected to hypoxia/ischemia; the compound counteracts inflammation, and influences mitochondrial status and proliferation potential in a PPARγ-dependent manner. Post-treatment with amorfrutin B decreased the IBA1 fluorescence intensity, reduced caspase-1 activity, and downregulated IL1B/IL-1β and TNFA but not IL10/IL-10 expression, which was upregulated. Amorfrutin B also stimulated PPARγ signaling, as evidenced by increased mRNA and/or protein levels of PPARγ and PGC1α. In addition, amorfrutin B reversed the hypoxia/ischemia-evoked effects on mitochondria-related parameters, such as mitochondrial membrane potential, BCL2/BCL2 expression and metabolic activity, which were correlated with diminished proliferation potential of microglia. Interestingly, the inhibitory effect of amorfrutin B on the proliferation potential and mitochondrial function of microglia is opposite to the stimulatory effect of amorfrutin B on mouse neuronal survival, as evidenced by increased neuronal viability and reduced neurodegeneration. In summary, this study showed for the first time that amorfrutin B compromises hypoxia/ischemia-induced activation of human microglia in a PPARγ-dependent manner, which involves inhibiting inflammation, normalizing mitochondrial status, and controlling proliferation potential. These data extend the protective potential of amorfrutin B in the pharmacotherapy of hypoxic/ischemic brain injury, targeting not only neurons but also activated microglia.

Pioglitazone Protects Against Hypoxia-Induced Cardiomyocyte Apoptosis Through Inhibiting NLRP3/Caspase-1 Pathway in vivo and in vitro

This study aims to explore the underlying mechanisms of how Pioglitazone (Pio) affects myocardial ischemia-reperfusion (I/R) injury. In this study, after pretreatment of Pio, the pathologic change of myocardial tissues was measured via hematoxylin and eosin staining. The release of lactate dehydrogenase (LDH), superoxide dismutase (SOD), and nitric oxide (NO) were measured. The cardiomyocyte apoptosis was detected via TUNEL assay and flow cytometry assay. The mitochondrial membrane potential (ΔΨm) was estimated using the JC-1 probe. The release of cytochrome c in mitochondria and the translocation of cytochrome c in the cytosol were measured using western blot. Additionally, apoptosis-associated molecules and NOD-like receptor pyrin domain containing-3 (NLRP3)/caspase-1 pathway-related molecules were measured using western blot, quantitative real-time-polymerase chain reaction, and immunofluorescence staining. Results showed that the pretreatment of Pio significantly decreased myocardial tissue damage. Pio pretreatment inhibited the release of creatine kinase and LDH but promoted NO release in serum and H9c2 cell supernatants. Moreover, the pretreatment of Pio notably alleviated cardiomyocyte apoptosis. Pio pretreatment also maintained the mitochondrial membrane potential and prevented cytochrome c release in H/R-induced cardiomyocytes. Additionally, we confirmed that Pio pretreatment inhibited cardiomyocyte apoptosis via repressing the NLRP3/caspase-1 pathway. In conclusion, our study demonstrated that Pio could inhibit myocardial I/R injury and cardiomyocyte apoptosis by inhibiting the activation of the NLRP3/caspase-1 signaling pathway.

Rethinking pioglitazone as a cardioprotective agent: a new perspective on an overlooked drug

Since 1985, the thiazolidinedione pioglitazone has been widely used as an insulin sensitizer drug for type 2 diabetes mellitus (T2DM). Although fluid retention was early recognized as a safety concern, data from clinical trials have not provided conclusive evidence for a benefit or a harm on cardiac function, leaving the question unanswered. We reviewed the available evidence encompassing both in vitro and in vivo studies in tissues, isolated organs, animals and humans, including the evidence generated by major clinical trials. Despite the increased risk of hospitalization for heart failure due to fluid retention, pioglitazone is consistently associated with reduced risk of myocardial infarction and ischemic stroke both in primary and secondary prevention, without any proven direct harm on the myocardium. Moreover, it reduces atherosclerosis progression, in-stent restenosis after coronary stent implantation, progression rate from persistent to permanent atrial fibrillation, and reablation rate in diabetic patients with paroxysmal atrial fibrillation after catheter ablation. In fact, human and animal studies consistently report direct beneficial effects on cardiomyocytes electrophysiology, energetic metabolism, ischemia–reperfusion injury, cardiac remodeling, neurohormonal activation, pulmonary circulation and biventricular systo-diastolic functions. The mechanisms involved may rely either on anti-remodeling properties (endothelium protective, inflammation-modulating, anti-proliferative and anti-fibrotic properties) and/or on metabolic (adipose tissue metabolism, increased HDL cholesterol) and neurohormonal (renin–angiotensin–aldosterone system, sympathetic nervous system, and adiponectin) modulation of the cardiovascular system. With appropriate prescription and titration, pioglitazone remains a useful tool in the arsenal of the clinical diabetologist.

Molecular Mechanisms of Cardiomyocyte Death in Drug-Induced Cardiotoxicity

Homeostatic regulation of cardiomyocytes plays a crucial role in maintaining the normal physiological activity of cardiac tissue. Severe cardiotoxicity results in cardiac diseases including but not limited to arrhythmia, myocardial infarction and myocardial hypertrophy. Drug-induced cardiotoxicity limits or forbids further use of the implicated drugs. Such drugs that are currently available in the clinic include anti-tumor drugs (doxorubicin, cisplatin, trastuzumab, etc.), antidiabetic drugs (rosiglitazone and pioglitazone), and an antiviral drug (zidovudine). This review focused on cardiomyocyte death forms and related mechanisms underlying clinical drug-induced cardiotoxicity, including apoptosis, autophagy, necrosis, necroptosis, pryoptosis, and ferroptosis. The key proteins involved in cardiomyocyte death signaling were discussed and evaluated, aiming to provide a theoretical basis and target for the prevention and treatment of drug-induced cardiotoxicity in the clinical practice.