Heme induced progesterone-resistant profiling and promotion of endometriosis in vitro and in vivo

Heme metabolism and HO-1 in the pathogenesis and potential intervention of endometriosis

Endometriosis (EM) is one of the diseases related to retrograded menstruation and hemoglobin. Heme, released from hemoglobin, is degraded by heme oxygenase-1 (HO-1). In EM lesions, heme metabolites regulate processes such as inflammation, redox balance, autophagy, dysmenorrhea, malignancy, and invasion, where macrophages (Mø) play a fundamental role in their interactions. Regulation occurs at molecular, cellular, and pathological levels. Numerous studies suggest that heme is an indispensable component in EM and may contribute to its pathogenesis. The regulatory role of heme in EM encompasses cytokines, signaling pathways, and kinases that mediate cellular responses to external stimuli. HO-1, a catalytic enzyme in the catabolic phase of heme, mitigates heme's cytotoxicity in EM due to its antioxidant, anti-inflammatory, and anti-proliferative properties. Certain compounds may intervene in EM by targeting heme metabolism, guiding the development of appropriate treatments for all stages of endometriosis.

Farnesoid X receptor overexpression prevents hepatic steatosis through inhibiting AIM2 inflammasome activation in nonalcoholic fatty liver disease

Oxidative stress-mediated activation of inflammasome has a significant effect on the pathogenesis of nonalcoholic fatty liver disease (NAFLD). Farnesoid X receptor (NR1H4, FXR) has been implicated in biological function and many diseases, including NAFLD. The regulatory effect of FXR on oxidative stress and whether this process is related with the activation of absent melanoma 2 (AIM2) inflammasome in NAFLD remain unclear. In the present research, we confirmed that FXR in the livers of steatosis patients is significantly reduced compared with normal liver tissue by using the Gene Expression Omnibus (GEO) database and a palmitic acid (PA) - mediated steatosis model in AML-12 cells. Under the premise of ensuring the same food intake as the control group, overexpression of FXR in mice attenuated HFD-mediated weight gain and liver steatosis, facilitated lipid metabolism, improved fatty acid β-oxidation, lipolysis, and reduced fatty acid synthesis and intake, which also inhibited the activation of AIM2 inflammasome. Overexpression of FXR alleviated PA-induced triglyceride (TG) accumulation, imbalance of lipid homeostasis, and the activation of AIM2 inflammasome in hepatic steatosis cells, while FXR knockdown appeared the opposite effects. FXR overexpression suppressed PA- and HFD-induced oxidative stress, but FXR siRNA demonstrated the opposite influence. The decreased ROS generation may be the reason why FXR weakens AIM2 activation when a fatty acid overload occurs. In conclusion, our results confirm that other than regulating lipid homeostasis and blocking NLRP3 inflammasome activation, FXR improves hepatic steatosis by a novel mechanism that inhibits oxidative stress and AIM2 inflammasome activation.

Proposal for targeted, neo-evolutionary-oriented secondary prevention of early-onset endometriosis and adenomyosis. Part II: medical interventions

According to consistent epidemiological data, the slope of the incidence curve of endometriosis rises rapidly and sharply around the age of 25 years. The delay in diagnosis is generally reported to be between 5 and 8 years in adult women, but it appears to be over 10 years in adolescents. If this is true, the actual onset of endometriosis in many young women would be chronologically placed in the early postmenarchal years. Ovulation and menstruation are inflammatory events that, when occurring repeatedly for years, may theoretically favour the early development of endometriosis and adenomyosis. Moreover, repeated acute dysmenorrhoea episodes after menarche may not only be an indicator of ensuing endometriosis or adenomyosis, but may also promote the transition from acute to chronic pelvic pain through central sensitization mechanisms, as well as the onset of chronic overlapping pain conditions. Therefore, secondary prevention aimed at reducing suffering, limiting lesion progression, and preserving future reproductive potential should be focused on the age group that could benefit most from the intervention, i.e. severely symptomatic adolescents. Early-onset endometriosis and adenomyosis should be promptly suspected even when physical and ultrasound findings are negative, and long-term ovulatory suppression may be established until conception seeking. As nowadays this could mean using hormonal therapies for several years, drug safety evaluation is crucial. In adolescents without recognized major contraindications to oestrogens, the use of very low-dose combined oral contraceptives is associated with a marginal increase in the individual absolute risk of thromboembolic events. Oral contraceptives containing oestradiol instead of ethinyl oestradiol may further limit such risk. Oral, subcutaneous, and intramuscular progestogens do not increase the thromboembolic risk, but may interfere with attainment of peak bone mass in young women. Levonorgestrel-releasing intra-uterine devices may be a safe alternative for adolescents, as amenorrhoea is frequently induced without suppression of the ovarian activity. With regard to oncological risk, the net effect of long-term oestrogen-progestogen combinations use is a small reduction in overall cancer risk. Whether surgery should be considered the first-line approach in young women with chronic pelvic pain symptoms seems questionable. Especially when large endometriomas or infiltrating lesions are not detected at pelvic imaging, laparoscopy should be reserved to adolescents who refuse hormonal treatments or in whom first-line medications are not effective, not tolerated, or contraindicated. Diagnostic and therapeutic algorithms, including self-reported outcome measures, for young individuals with a clinical suspicion of early-onset endometriosis or adenomyosis are proposed.

The role of mitochondrial dynamics in the pathophysiology of endometriosis

AIM

Endometriosis is a chronic disease of reproductive age, associated with pelvic pain and infertility. Endometriotic cells adapt to changing environments such as oxidative stress and hypoxia in order to survive. However, the underlying mechanisms remain to be fully elucidated. In this review, we summarize our current understanding of the pathogenesis of endometriosis, focusing primarily on the molecular basis of energy metabolism, redox homeostasis, and mitochondrial function, and discuss perspectives on future research directions.

METHODS

Papers published up to March 31, 2023 in the PubMed and Google Scholar databases were included in this narrative literature review.

RESULTS

Mitochondria serve as a central hub sensing a multitude of physiological processes, including energy production and cellular redox homeostasis. Under hypoxia, endometriotic cells favor glycolysis and actively produce pyruvate, nicotinamide adenine dinucleotide phosphate (NADPH), and other metabolites for cell proliferation. Mitochondrial fission and fusion dynamics may regulate the phenotypic plasticity of cellular energy metabolism, that is, aerobic glycolysis or OXPHOS. Endometriotic cells have been reported to have reduced mitochondrial numbers, increased lamellar cristae, improved energy efficiency, and enhanced cell proliferation and survival. Increased mitochondrial fission and fusion turnover by hypoxic and normoxic conditions suggests an activation of mitochondrial quality control mechanisms. Recently, candidate molecules that influence mitochondrial dynamics have begun to be identified.

CONCLUSION

This review suggests that unique energy metabolism and redox homeostasis driven by mitochondrial dynamics may be linked to the pathophysiology of endometriosis. However, further studies are needed to elucidate the regulatory mechanisms of mitochondrial dynamics in endometriosis.