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

G protein-coupled estrogen receptor biased signaling in health and disease

G protein-coupled estrogen receptor (GPER) is now recognized for its pivotal role in cellular signaling, influencing diverse physiological processes and disease states. Unlike classical estrogen receptors, GPER exhibits biased signaling, wherein ligand binding triggers selective pathways over others, significantly impacting cellular responses. This review explores the nuanced mechanisms of biased signaling mediated by GPER, underscoring its relevance in cardiovascular health, neurological function, immune modulation, and oncogenic processes. Despite its critical implications, biased signaling through GPER remains underexplored compared to traditional signaling paradigms. We explore recent progress in understanding GPER signaling specificity and its potential therapeutic implications across various diseases. Future research directions aim to uncover the molecular basis of biased signaling, develop selective ligands, and translate these insights into personalized therapeutic approaches. Exploiting the therapeutic potential of GPER biased signaling represents a promising frontier in precision medicine, offering innovative strategies to address unmet medical needs.

Mitochondria at the Heart of Sepsis: Mechanisms, Metabolism, and Sex Differences

Sepsis is a life-threatening condition that occurs when the body is unable to effectively combat infection, leading to systemic inflammation and multi-organ failure. Interestingly, females exhibit lower sepsis incidence and improved clinical outcomes compared to males. However, the mechanisms underlying these sex-specific differences remain poorly understood. While sex hormones have been a primary focus, emerging evidence suggests that non-hormonal factors also play contributory roles. Despite sex differences in sepsis, clinical management is the same for both males and females, with treatment focused on combating infection using antibiotics and hemodynamic support through fluid therapy. However, even with these interventions, mortality remains high, highlighting the need for more effective and targeted therapeutic strategies. Sepsis-induced cardiomyopathy (SIC) is a key contributor to multi-organ failure and is characterized by left ventricular dilation and impaired cardiac contractility. In this review, we explore sex-specific differences in sepsis and SIC, with a particular focus on mitochondrial metabolism. Mitochondria generate the ATP required for cardiac function through fatty acid and glucose oxidation, and recent studies have revealed distinct metabolic profiles between males and females, which can further differ in the context of sepsis and SIC. Targeting these metabolic pathways could provide new avenues for sepsis treatment.

Maternal Nutritional Programming: Sex-Specific Cardiovascular and Immune Outcomes Following Perinatal High-Fat Diet Exposure

Background: The long-term effects of a perinatal high-fat diet on the cardiovascular function of offspring are not well elucidated. We hypothesize that perinatal exposure to a high-fat diet alters adult cardiovascular and immune responses in a sex-specific manner. Methods: Male and female offspring were born to perinatal high-fat (pHFD) or control diet (pCD)-fed C57BL/6 mothers and weaned to a control diet. Cardiovascular function (baseline and response to an acute isoproterenol stress test) was quantified at 8 weeks of age, and acute blood inflammatory response to a single low dose of lipopolysaccharide at 9 weeks of age. Results: Male pHFD offspring had identical baseline cardiovascular function compared to pCD mice but a blunted response to isoproterenol (20-45% reductions in cardiac output, stroke volume, and left ventricular fractional shortening). In contrast, baseline cardiovascular parameters were reduced in female pHFD compared to pCD offspring, but there was no effect of perinatal diet on response to isoproterenol. Concentrations of TNF-α and IL-6 in plasma two hours after a low-dose LPS administration were highest in female pCD mice. Conclusions: Perinatal high-fat diet exposure resulted in sex-specific adaptations in cardiovascular function and immune response. Female offspring displayed baseline impairments, whereas male offspring showed latent vulnerability under stress. These differences may reflect underlying hormonal or epigenetic mechanisms that diverge by sex. Future studies should examine the roles of sex hormones and gene regulation pathways to better understand these dimorphic outcomes. These findings emphasize the importance of maternal diet in shaping offspring cardiometabolic risks and highlight potential avenues for nutritional interventions during pregnancy.

Nicotinamide mononucleotide protects septic hearts in mice via preventing cyclophilin F modification and lysosomal dysfunction

Myocardial dysfunction is a decisive factor of death in septic patients. Cyclophilin F (PPIF) is a major component of the mitochondrial permeability transition pore (mPTP) and acts as a critical mPTP sensitizer triggering mPTP opening. In sepsis, decreased NAD+ impairs Sirtuin 3 function, which may prevent PPIF de-acetylation. Repletion of NAD+ with nicotinamide mononucleotide (NMN) reduces myocardial dysfunction in septic mice. In addition, administration of the mPTP inhibitor cyclosporine-A attenuated sepsis-induced myocardial dysfunction, and deletion of PPIF reduced lung and liver injuries in sepsis, leading to increased survival. It is plausible that NAD+ repletion with NMN may prevent mPTP opening in protecting septic hearts through PPIF de-acetylation and/or inhibition of mitochondrial ROS-mediated PPIF oxidation. In this study we investigated how NMN alleviated myocardial dysfunction in septic mice. Sepsis was induced in mice by injection of LPS (4 mg/kg, i.p.). Then mice received NMN (500 mg/kg, i.p.) or mito-TEMPO (0.7 mg/kg, i.p.) right after LPS injection, and subjected to echocardiography for assessing myocardial function. At the end of experiment, the heart tissues and sera were collected for analyses. In vitro experiments were conducted in neonatal mouse cardiomyocytes treated with LPS (1 µg/mL) in the presence of NMN (500 µmol/L) or mito-TEMPO (25 nmol/L). We showed that LPS treatment markedly increased mitochondrial ROS production and induced lysosomal dysfunction and aberrant autophagy in cardiomyocytes and mouse hearts, leading to inflammatory responses and myocardial injury and dysfunction in septic mice. NMN administration attenuated LPS-induced deteriorative effects. Selective inhibition of mitochondrial superoxide production with mito-TEMPO attenuated lysosomal dysfunction and aberrant autophagy in septic mouse hearts. Notably, LPS treatment significantly increased acetylation and oxidation of PPIF, which was prevented by NMN in mouse hearts. Knockdown of PPIF replicated the beneficial effects of NMN or mito-TEMPO on ROS production, lysosomal dysfunction, aberrant autophagy, and myocardial injury/dysfunction in sepsis. In addition, administration of NMN abrogated LPS-induced ATP5A1 acetylation and increased ATP5A1 protein levels and ATP production in septic mouse hearts. This study demonstrates that NMN modulates the interplay of mitochondrial ROS and PPIF in maintaining normal lysosomal function and autophagy and protecting ATP5A1 and ATP production during sepsis.

Pleiotropic Role of TNIK in Sepsis-Induced Cardiomyopathy

Heart failure induced by sepsis is considered one of the foremost contributors to mortality in intensive care unit (ICU) patients. However, the molecular mechanism of myocardial damage in sepsis has not been fully elucidated at present. TNF receptor-associated factor-2 and Nck-interacting protein kinase (TNIK) are members of the germinal center kinase superfamily. TNIK exhibits a pivotal role as a conserved modulator of glucose and lipid homeostasis. Here, we aimed to investigate the potential direct roles of TNIK and whether TNIK exerts anti-septic myocardial damage by regulating the NLRP3 pathway. We initially revealed that TNIK was the crucial involvement of septic myocardial injury. Subsequently, we constructed a cecal ligation and puncture (CLP) mouse model and employed LPS-induced injury in HL-1 cardiomyocytes. Our observations revealed an upregulation of TNIK levels in both CLP-injured mice and LPS-treated HL-1 cells. However, TNIK inhibitor TNIK-IN-7 or siRNA attenuated cardiomyocyte LPS injury. Especially, TNIK siRNA can significantly downregulate TNIK as well as decrease NLRP3 and IL-1β mRNA and protein levels, though the explicit molecular mechanisms of TNIK-NLRP3 in septic myocardial require further investigation. Together, our investigation presents novel evidence suggesting TNIK as a potential therapeutic target for the prevention and therapeutic intervention in sepsis-induced cardiomyopathy.

Estrogen via GPER downregulated HIF-1a and MIF expression, attenuated cardiac arrhythmias, and myocardial inflammation during hypobaric hypoxia

BACKGROUND

The human body is highly dependent on adequate oxygenation of the cellular space for physiologic homeostasis mediation. The insufficient oxygenation of the cellular space leads to hypoxia. Hypobaric hypoxia (HH) is the reduction in oxygen partial pressure and atmospheric pressure during ascent to high altitudes. This state induces a maladaptive response. Women and how hormones like estrogen influence hypoxia have not been explored with most research being conducted on males. In this study, we investigated the effects of estrogen and GPER on HIF-1a and MIF expression, cardiac arrhythmias, and inflammation during hypobaric hypoxia.

METHODS

Ovariectomy and SHAM operations were done on FVB wild-type (WT) female mice. 2 weeks after the operation, the mice were treated with estrogen (40 mg/kg) as a therapeutic intervention and placed in a hypoxic chamber at an altitude of 6000 m for 7 days. Cardiac electrical activity was assessed using electrocardiography. Alterations in protein expression, inflammatory, and GPER pathways were investigated using western blotting, ELISA, and immunofluorescence. Histological assessment was performed using Masson's trichrome staining. Peritoneal macrophages were isolated for in vitro study.

RESULTS

Under hypobaric hypoxia (HH), the ovariectomized (OVX) group showed increased macrophage migration inhibitory factor (MIF) and hypoxia-inducible factor-1 alpha (HIF-1α) expression. In contrast, these factors were downregulated in the estrogen-treated and control groups. HH also caused cardiac inflammation and fibrosis, especially in the OVX + HH group, which had elevated proinflammatory cytokines (IL-1β, IL-6, TNF-α) and decreased anti-inflammatory cytokines (TGF-β, IL-10). Inhibition with G15 (a GPER antagonist) increased MIF and HIF-1α, whereas activation with G1 (a GPER agonist) decreased their expression, highlighting GPER's crucial role in regulating MIF during HH.

CONCLUSION

Estrogen regulates HIF-1α and MIF expression through the GPER during hypobaric hypoxia, suggesting a potential therapeutic pathway to mitigate maladaptive responses during high-altitude ascent.

Role and Mechanism of Mitochondrial Ribosomal Proteins in Septic Myocardial Injury

Objective

To investigate the role of mitochondrial ribosomal proteins (MRPs) in the pathogenesis and progression of septic myocardial injury. Additionally, we aim to propose new technical strategies and experimental foundations for the prevention and treatment of septic myocardial injury.

Methods

Animal and cell models of septic myocardial injury were established. Aberrantly expressed MRPs were screened using transcriptome sequencing, and their expression was verified by RT-qPCR and Western blot. Subsequently, overexpressed and knockdown cell models of myocardial injury were constructed. The effects on CO I, PGC-1α, ATP content, ROS fluorescence intensity, mitochondrial membrane potential, and GSDMD were assessed, along with changes in caspase-4 and IL-1β expression levels.

Results

Transcriptome sequencing revealed a reduction in MRPs expression in mice with septic myocardial injury. Both RT-qPCR and Western blot analysis confirmed the decreased expression of MRPs in animal and cell models of septic myocardial injury. Furthermore, overexpression of both MRPS16 and MRPL47 mitigated the decrease in CO I and PGC-1α levels induced by septic myocardial injury. Additionally, overexpression of MRPS16 and MRPL47 alleviated the elevated levels of IL-1β, caspase-4, and GSDMD caused by septic myocardial injury.

Conclusion

The findings suggest that both MRPS16 and MRPL47 can mitigate mitochondrial injury by attenuating mitochondrial biosynthesis dysfunction, energy metabolism disorders, and Ca2+ disturbances caused by septic myocardial injury. This ultimately reduces cellular damage and alleviates septic myocardial injury.

NLRP3 Inflammasome Targeting Offers a Novel Therapeutic Paradigm for Sepsis-Induced Myocardial Injury

Cardiac or myocardial dysfunction induced by sepsis, known as sepsis-induced cardiomyopathy or sepsis-induced myocardial injury (SIMI), is a common complication of sepsis and is associated with poor outcomes. However, the pathogenesis and molecular mechanisms underlying SIMI remain poorly understood, requiring further investigations. Emerging evidence has shown that NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasomes contribute to SIMI. Compounds that inhibit NLRP3-associated pyroptosis may exert therapeutic effects against SIMI. In this review, we first outlined the principal elements of the NLRP3 signaling cascade and summarized the recent studies highlighting how NLRP3 activation contributes to the pathogenesis of SIMI. We outlined selective small-molecule modulators that function as NLRP3 inhibitors and delineated their mechanisms of action to attenuate SIMI. Finally, we discuss the major limitations of the current therapeutic paradigm and propose possible strategies to overcome them. This review highlights the pharmacological inhibition of SIMI as a promising therapeutic strategy.

GPR30 Agonist G1 Mitigates Sepsis-Induced Cardiac Dysfunction by Inhibiting ACE2/c-FOS-Mediated Necroptosis in Female Mice

Sepsis is a severe inflammatory syndrome with high mortality and morbidity. Sepsis-induced myocardial dysfunction (SIMD) is a common cause of death in sepsis. The female sex is less susceptible to sepsis-related organ dysfunction, although the underlying mechanism of this sex difference remains unclear. This study explored the role of estrogen receptor G protein-coupled estrogen receptor 30 (GPR30) in septic cardiac dysfunction. Results from the present study indicated that GPR30 activation by the G1 agonist protected female mouse hearts against SIMD exposed to lipopolysaccharides. However, this beneficial effect was absent in female ACE2-knockout mice, as demonstrated by poorer cardiac contractility, myocardial injury, and necroptosis. We also demonstrated that the Stat6 transcription factor induced ace2 transcription by enhancing its promoter activity under GPR30 activation in septic hearts. The adenovirus-mediated inhibition of ACE2 targeting c-FOS expression reversed the deterioration, restored cardiac function, and improved survival in female ACE2-knockout mice. These results demonstrate the essential role of GPR30/STAT6/ACE2/c-FOS-mediated necroptosis in G1-mediated protection and provide novel insight into the pathogenesis of sepsis-related organ damage.

GPER1 signaling restricts macrophage proliferation and accumulation in human hepatocellular carcinoma

Background

Sex hormones and their related receptors have been reported to impact the development and progression of tumors. However, their influence on the composition and function of the tumor microenvironment is not well understood. We aimed to investigate the influence of sex disparities on the proliferation and accumulation of macrophages, one of the major components of the tumor microenvironment, in hepatocellular carcinoma (HCC).

Methods

Immunohistochemistry was applied to assess the density of immune cells in HCC tissues. The role of sex hormone related signaling in macrophage proliferation was determined by immunofluorescence and flow cytometry. The underlying regulatory mechanisms were examined with both in vitro experiments and murine HCC models.

Results

We found higher levels of macrophage proliferation and density in tumor tissues from male patients compared to females. The expression of G protein-coupled estrogen receptor 1 (GPER1), a non-classical estrogen receptor, was significantly decreased in proliferating macrophages, and was inversely correlated with macrophage proliferation in HCC tumors. Activation of GPER1 signaling with a selective agonist G-1 suppressed macrophage proliferation by downregulating the MEK/ERK pathway. Additionally, G-1 treatment reduced PD-L1 expression on macrophages and delayed tumor growth in mice. Moreover, patients with a higher percentage of GPER1+ macrophages exhibited longer overall survival and recurrence-free survival compared to those with a lower level.

Conclusions

These findings reveal a novel role of GPER1 signaling in regulating macrophage proliferation and function in HCC tumors and may offer a potential strategy for designing therapies based on understanding sex-related disparities of patients.