CD73/adenosine axis exerts cardioprotection against hypobaric hypoxia-induced metabolic shift and myocarditis in a sex-dependent manner.

BACKGROUND: Clinical and experimental studies have shown that the myocardial inflammatory response during pathological events varies between males and females. However, the cellular and molecular mechanisms of these sex differences remain elusive. CD73/adenosine axis has been linked to anti-inflammatory responses, but its sex-specific cardioprotective role is unclear. The present study aimed to investigate whether the CD73/adenosine axis elicits sex-dependent cardioprotection during metabolic changes and myocarditis induced by hypobaric hypoxia. METHODS: For 7 days, male and female mice received daily injections of the CD73 inhibitor adenosine 5'- (α, ß-methylene) diphosphate (APCP) 10 mg/kg/day while they were kept under normobaric normoxic and hypobaric hypoxic conditions. We evaluated the effects of hypobaric hypoxia on the CD73/adenosine axis, myocardial hypertrophy, and cardiac electrical activity and function. In addition, metabolic homeostasis and immunoregulation were investigated to clarify the sex-dependent cardioprotection of the CD73/adenosine axis. RESULTS: Hypobaric hypoxia-induced cardiac dysfunction and adverse remodeling were more pronounced in male mice. Also, male mice had hyperactivity of the CD73/adenosine axis, which aggravated myocarditis and metabolic shift compared to female mice. In addition, CD73 inhibition triggered prostatic acid phosphatase ectonucleotidase enzymatic activity to sustain adenosine overproduction in male mice but not in female mice. Moreover, dual inhibition prostatic acid phosphatase and CD73 enzymatic activities in male mice moderated adenosine content, alleviating glycolytic shift and proinflammatory response. CONCLUSION: The CD73/adenosine axis confers a sex-dependent cardioprotection. In addition, extracellular adenosine production in the hearts of male mice is influenced by prostatic acid phosphatase and tissue nonspecific alkaline phosphatase.

Estradiol contributes to sex differences in resilience to sepsis-induced metabolic dysregulation and dysfunction in the heart via GPER-1-mediated PPARδ/NLRP3 signaling.

BACKGROUND AND AIM: Clinically, septic males tend to have higher mortality rates, but it is unclear if this is due to sex differences in cardiac dysfunction, possibly influenced by hormonal variations. Cardiac dysfunction significantly contributes to sepsis-related mortality, primarily influenced by metabolic imbalances. Peroxisome proliferator-activated receptor delta (PPARδ) is a key player in cardiac metabolism and its activation has been demonstrated to favor sepsis outcomes. While estradiol (E2) is abundant and beneficial in females, its impact on PPARδ-mediated metabolism in the heart with regards to sex during sepsis remains unknown. METHODS AND RESULTS: Here, we unveil that while sepsis diminishes PPARδ nuclear translocation and induces metabolic dysregulation, oxidative stress, apoptosis and dysfunction in the heart thereby enhancing mortality, these effects are notably more pronounced in males than females. Mechanistic experiments employing ovariectomized(OVX) mice, E2 administration, and G protein-coupled estrogen receptor 1(GPER-1) knockout (KO) mice revealed that under lipopolysaccharide (LPS)-induced sepsis, E2 acting via GPER-1 enhances cardiac electrical activity and function, promotes PPARδ nuclear translocation, and subsequently ameliorates cardiac metabolism while mitigating oxidative stress and apoptosis in females. Furthermore, PPARδ specific activation using GW501516 in female GPER-1-/- mice reduced oxidative stress, ultimately decreasing NLRP3 expression in the heart. Remarkably, targeted GPER-1 activation using G1 in males mirrors these benefits, improving cardiac electrical activity and function, and ultimately enhancing survival rates during LPS challenge. By employing NLRP3 KO mice, we demonstrated that the targeted GPER-1 activation mitigated injury, enhanced metabolism, and reduced apoptosis in the heart of male mice via the downregulation of NLRP3. CONCLUSION: Our findings collectively illuminate the sex-specific cardiac mechanisms influencing sepsis mortality, offering insights into physiological and pathological dimensions. From a pharmacological standpoint, this study introduces specific GPER-1 activation as a promising therapeutic intervention for males under septic conditions. These discoveries advance our understanding of the sex differences in sepsis-induced cardiac dysfunction and also present a novel avenue for targeted interventions with potential translational impact.