Chronic catecholamine stress (CCS) induces the occurrence of cardiomyopathy—pathological cardiac hypertrophy (PCH), which is characterized by left ventricular systolic dysfunction (LVSD). Recently, mounting evidence has implicated myocardial inflammation in the exacerbation of pathological cardiac remodeling. However, there are currently no well-defined treatment interventions or regimes targeted at both the attenuation of maladaptive myocardial hypertrophy and inflammation during CCS to prevent PCH. G protein-coupled receptor kinase 5 (GRK5) and adenylyl cyclases (ACs)-cAMP mediates both cardiac and inflammatory responses. Also, GRK5 and ACs are implicated in stress-induced LVSD. Herein, we aimed at preventing PCH during CCS via modulating adaptive cardiac and inflammatory responses by inhibiting GRK5 and/or stimulating ACs. Isoproterenol-induced cardiomyopathy (ICM) was modeled using 0.5 mg/100 g/day isoproterenol injections for 40 days. Alterations in cardiac and inflammatory responses were assessed from the myocardia. Similarities in the immunogenicity of cardiac troponin I (cTnI) and lipopolysaccharide under CCS were assessed, and Amlexanox (35 μM/ml) and/or Forskolin (10 μM/ml) were then employed in vitro to modulate adaptive inflammatory responses by inhibiting GRK5 or activating ACs-cAMP, respectively. Subsequently, Amlexanox (2.5 mg/100 g/day) and/or Forskolin (0.5 mg/100 g/day) were then translated into in vivo during CCS to modulate adaptive cardiac and inflammatory responses. The effects of Amlexanox and Forskolin on regulating myocardial systolic functions and inflammatory responses during CCS were ascertained afterward. PCH mice had excessive myocardial hypertrophy, fibrosis, and aggravated LVSD, which were accompanied by massive CD68+ inflammatory cell infiltrations. In vitro, Forskolin-AC/cAMP was effective than Amlexanox-GRK5 at downregulating proinflammatory responses during stress; nonetheless, Amlexanox and Forskolin combination demonstrated the most efficacy in modulating adaptive inflammatory responses. Individually, the translated Amlexanox and Forskolin treatment interventions were ineffective at subduing the pathological remodeling and sustaining cardiac function during CCS. However, their combination was potent at preventing LVSD during CCS by attenuating maladaptive myocardial hypertrophy, fibrosis, and inflammatory responses. The treatment intervention attained its potency mainly via Forskolin-ACs/cAMP-mediated modulation of cardiac and inflammatory responses, coupled with Amlexanox inhibition of GRK5 mediated maladaptive cascades. Taken together, our findings highlight the Amlexanox and Forskolin combination as a potential therapeutic intervention for preventing the occurrence of pathological cardiac hypertrophy during chronic stress.

Heart failure (HF) remains a public health concern as it is associated with high morbidity and death rates. In particular, heart failure with preserved ejection fraction (HFpEF) represents the dominant (>50%) form of HF and mostly occurring among postmenopausal women. Hence, the initiation and progression of the left ventricular diastolic dysfunctions (LVDD) (a typically clinical manifestation of HFpEF) in postmenopausal women have been attributed to estrogen deficiency and the loss of its residue cardioprotective effects. In this review, from a pathophysiological and immunological standpoint, we discuss the probable multiple pathomechanisms resulting in HFpEF, which are facilitated by estrogen deficiency. The initial discussions recap estrogen and estrogen receptors (ERs) and β-adrenergic receptors (βARs) signaling under physiological/pathological states to facilitate cardiac function/dysfunction, respectively. By reconciling these prior discussions, attempts were made to explain how the loss of estrogen facilitates the disruptions both ERs and βARs-mediated signaling responsible for; the modulation of intra-cardiomyocyte calcium homeostasis, maintenance of cardiomyocyte cytoskeletal and extracellular matrix, the adaptive regulation of coronary microvascular endothelial functions and myocardial inflammatory responses. By scaffolding the disruption of these crucial intra- and extra-cardiomyocyte physiological functions, estrogen deficiency has been demonstrated to cause LVDD and increase the incidence of HFpEF in postmenopausal women. Finally, updates on the advancements in treatment interventions for the prevention of HFpEF were highlighted.

Clinical demographics have demonstrated that postmenopausal women are predisposed to chronic stress-induced cardiomyopathy (CSC) and this has been associated with the decrease of estrogen. Meanwhile, recent studies have implicated unsolved myocardial proinflammatory responses, which are characterized by enormous CD86+ macrophage infiltrations as an underlying disease mechanism expediting the pathological remodeling of the heart during chronic stress. However, we had previously demonstrated that estrogen confers cardioprotection via the modulation of cardiomyocytes β2-adrenoceptors (β2AR)-Gs/Gi pathways during stress to lessen the incidence of stress-induced cardiovascular diseases in premenopausal women. Intriguingly, macrophages express β2AR profoundly as well; as such, we sought to elucidate the possibilities of estrogen modulating β2AR-Gs/Gi pathway to confer cardioprotection during stress via immunomodulation. To do this, ovariectomy (OVX) and sham operations (Sham) were performed on female Sprague-Dawley (SD) rats. Two weeks after OVX, the rats were injected with 40 μg/kg/day of estradiol (E2). Next, on day 36 after OVX, chronic stress was induced by a daily subcutaneous injection of 5 mg/kg/day of isoproterenol (ISO). The effect of E2 on relevant clinical cardiac function indexes (LVSP, LVEDP, + dp/dt and −dp/dt), myocardial architecture (cardiomyocyte diameter and fibrosis), β2AR alterations, and macrophage (CD86+ and CD206+) infiltrations were assessed. In vitro, peritoneal macrophages (PMΦ) were isolated from wild-type and β2AR-knockout female mice. The PMΦ were treated with ISO, E2, and β2AR blocker ICI 118,551 for 24 h, and flow cytometric evaluations were done to assess their phenotypic expression. E2 deficiency permitted the induction of CSC, which was characterized by cardiac dysfunctions, maladaptive myocardial hypertrophy, unresolved proinflammatory responses, and fibrosis. Nonetheless, E2 presence/supplementation during stress averted all the aforementioned adverse effects of chronic stress while preventing excessive depletion of β2AR. Also, we demonstrated that E2 facilitates timely resolution of myocardial proinflammation to permit reparative functions by enhancing the polarization of CD86+ to CD206+ macrophages. However, this adaptive immunomodulation is hampered when β2AR is inhibited. Taken together, the outcomes of this study show that E2 confers cardioprotection to prevent CSC via adaptive immunomodulation of macrophage phenotypes, and β2AR-mediated signaling is crucial for the polarizations of CD86+ to CD206+ macrophages.

BackgroundSea-level residents experience altitude sickness when they hike or visit altitudes above ~2,500 m due to the hypobaric hypoxia (HH) conditions at such places. HH has been shown to drive cardiac inflammation in both ventricles by inducing maladaptive metabolic reprogramming of macrophages, which evokes aggravated proinflammatory responses, promoting myocarditis, fibrotic remodeling, arrhythmias, heart failure, and sudden deaths. The use of salidroside or altitude preconditioning (AP) before visiting high altitudes has been extensively shown to exert cardioprotective effects. Even so, both therapeutic interventions have geographical limitations and/or are inaccessible/unavailable to the majority of the population as drawbacks. Meanwhile, occlusion preconditioning (OP) has been extensively demonstrated to prevent hypoxia-induced cardiomyocyte damage by triggering endogenous cardioprotective cascades to mitigate myocardial damage. Herein, with the notion that OP can be conveniently applied anywhere, we sought to explore it as an alternative therapeutic intervention for preventing HH-induced myocarditis, remodeling, and arrhythmias.MethodsOP intervention (6 cycles of 5 min occlusion with 200 mmHg for 5 min and 5 min reperfusion at 0 mmHg – applying to alternate hindlimb daily for 7 consecutive days) was performed, and its impact on cardiac electric activity, immunoregulation, myocardial remodeling, metabolic homeostasis, oxidative stress responses, and behavioral outcomes were assessed before and after exposure to HH in mice. In humans, before and after the application of OP intervention (6 cycles of 5 min occlusion with 130% of systolic pressure and 5 min reperfusion at 0 mmHg – applying to alternate upper limb daily for 6 consecutive days), all subjects were assessed by cardiopulmonary exercise testing (CPET).ResultsComparing the outcomes of OP to AP intervention, we observed that similar to the latter, OP preserved cardiac electric activity, mitigated maladaptive myocardial remodeling, induced adaptive immunomodulation and metabolic homeostasis in the heart, enhanced antioxidant defenses, and conferred resistance against HH-induce anxiety-related behavior. Additionally, OP enhanced respiratory and oxygen-carrying capacity, metabolic homeostasis, and endurance in humans.ConclusionsOverall, these findings demonstrate that OP is a potent alternative therapeutic intervention for preventing hypoxia-induced myocarditis, cardiac remodeling, arrhythmias, and cardiometabolic disorders and could potentially ameliorate the progression of other inflammatory, metabolic, and oxidative stress-related diseases.

The increasing incidence of stress-induced cardiomyopathy is due to the complexities of our modern-day lives, which constantly elicit stress responses. Herein, we aimed to explore the therapeutic potential of Amlexanox and Forskolin in promoting the recovery from stress-induced cardiomyopathy. Isoproterenol-induced cardiomyopathy (ICM) models were made, and the following treatment interventions were administered: 5% v/v DMSO as a placebo, Amlexanox (2.5 mg/100 g/day) treatment, Forskolin (0.5 mg/100 g/day), and Amlexanox and Forskolin combination, at their respective aforementioned dosages. The effects of Amlexanox and Forskolin treatment on ICM models were assessed by eletrocardiography and echocardiography. Also, using histological analysis and ELISA, their impact on myocardial architecture and inflammation were ascertained. ICM mice had excessive myocardial fibrosis, hypertrophy, and aggravated LVSDs which were accompanied by massive CD86+ inflammatory cells infiltration. Amlexanox treatment attenuated the myocardial hypertrophy, fibrosis, and inflammation and also slightly improved systolic functions. Meanwhile, forskolin treatment resulted in arrhythmias but significantly enhanced the resolution of myocardial fibrosis and inflammation. Intriguingly, Amlexanox and Forskolin combination demonstrated the most potency at promoting the recovery of the ICM from LVSD by attenuating maladaptive myocardial hypertrophy, fibrosis, and inflammatory responses. Our findings highlight the Amlexanox and Forskolin combination as a potential therapeutic intervention for enhancing cardiac function recovery from stress-induced cardiomyopathy by promoting the resolution of maladaptive cardiac remodeling.