Brain Testosterone-CYP1B1 (Cytochrome P450 1B1) Generated Metabolite 6β-Hydroxytestosterone Promotes Neurogenic Hypertension and Inflammation

Maternal social environment shapes yolk testosterone allocation and embryonic neural gene expression in tree swallows

Offspring from females breeding in competitive social environments are often exposed to more testosterone (T) during embryonic development, which can affect traits from growth to behavior in potentially adaptive ways. Despite the important role of maternally derived steroids in shaping offspring development, the molecular mechanisms driving these processes are currently unclear. Here, we use tree swallows (Tachycineta bicolor) to explore the effects of the maternal social environment on yolk T concentrations and genome-wide patterns of neural gene expression in embryos. We measured aggressive interactions among females breeding at variable densities and collected their eggs at two timepoints, including the day laid to measure yolk T concentrations and on embryonic day 11 to measure gene expression in whole brain samples. We found that females breeding in high-density sites experienced elevated rates of physical aggression and their eggs had higher yolk T concentrations. A differential gene expression and weighted gene co-expression network analysis indicated that embryos from high-density sites experienced an upregulation of genes involved in hormone, circulatory, and immune processes, and these gene expression patterns were correlated with yolk T levels and aggression. Genes implicated in neural development were additionally downregulated in embryos from high-density sites. These data highlight how early neurogenomic processes may be affected by the maternal social environment, giving rise to phenotypic plasticity in offspring.

Melatonin alleviates ischemic stroke by inhibiting ferroptosis through the CYP1B1/ACSL4 pathway

This study utilized middle cerebral artery occlusion (MCAO) mouse models and HT-22 cell oxygen and glucose deprivation/reoxygenation (OGD/R) models to investigate the therapeutic effects of melatonin on ischemic brain injury. In the experiments, MCAO mice were treated with 5 and 10 mg/kg doses of melatonin, and H-T22 cells underwent OGD/R treatment and were administered different concentrations of melatonin. The results showed that melatonin significantly reduced ischemic brain area, neural damage, cerebral edema, and neuronal apoptosis in MCAO mice. In the HT-22 cell model, melatonin also improved cell proliferation ability, reduced apoptosis, and ROS production. Further mechanistic studies found that melatonin exerts protective effects by inhibiting ferroptosis, an iron-dependent form of regulated cell death, through regulation of the ACSL4/CYP1B1 pathway. In MCAO mice, melatonin decreased lipid peroxidation, ROS production, and ACSL4 protein expression. Overexpression of CYP1B1 increased ACSL4 ubiquitination and degradation, thereby increasing cell tolerance to ferroptosis, reducing ACSL4 protein levels, and decreasing ROS production. CYP1B1 knockdown obtained opposite results. The CYP1B1 metabolite 20-HETE induces expression of the E3 ubiquitin ligase FBXO10 by activating PKC signaling, which promotes ACSL4 degradation. In the OGD/R cell model, inhibition of CYP1B1 expression reversed the therapeutic effects of melatonin. In summary, this study demonstrates that melatonin protects the brain from ischemic injury by inhibiting ferroptosis through regulation of the ACSL4/CYP1B1 pathway, providing evidence for new therapeutic targets for ischemic brain injury.

Sex differences in blood pressure regulation and hypertension: renal, hemodynamic, and hormonal mechanisms

The teleology of sex differences has been argued since at least as early as Aristotle's controversial Generation of Animals more than 300 years BC, which reflects the sex bias of the time to contemporary readers. Although the question "why are the sexes different" remains a topic of debate in the present day in metaphysics, the recent emphasis on sex comparison in research studies has led to the question "how are the sexes different" being addressed in health science through numerous observational studies in both health and disease susceptibility, including blood pressure regulation and hypertension. These efforts have resulted in better understanding of differences in males and females at the molecular level that partially explain their differences in vascular function and renal sodium handling and hence blood pressure and the consequential cardiovascular and kidney disease risks in hypertension. This review focuses on clinical studies comparing differences between men and women in blood pressure over the life span and response to dietary sodium and highlights experimental models investigating sexual dimorphism in the renin-angiotensin-aldosterone, vascular, sympathetic nervous, and immune systems, endothelin, the major renal sodium transporters/exchangers/channels, and the impact of sex hormones on these systems in blood pressure homeostasis. Understanding the mechanisms governing sex differences in blood pressure regulation could guide novel therapeutic approaches in a sex-specific manner to lower cardiovascular risks in hypertension and advance personalized medicine.

NLRP3 Inflammasome’s Activation in Acute and Chronic Brain Diseases—An Update on Pathogenetic Mechanisms and Therapeutic Perspectives with Respect to Other Inflammasomes

Increasingly prevalent acute and chronic human brain diseases are scourges for the elderly. Besides the lack of therapies, these ailments share a neuroinflammation that is triggered/sustained by different innate immunity-related protein oligomers called inflammasomes. Relevant neuroinflammation players such as microglia/monocytes typically exhibit a strong NLRP3 inflammasome activation. Hence the idea that NLRP3 suppression might solve neurodegenerative ailments. Here we review the recent Literature about this topic. First, we update conditions and mechanisms, including RNAs, extracellular vesicles/exosomes, endogenous compounds, and ethnic/pharmacological agents/extracts regulating NLRP3 function. Second, we pinpoint NLRP3-activating mechanisms and known NLRP3 inhibition effects in acute (ischemia, stroke, hemorrhage), chronic (Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, MS, ALS), and virus-induced (Zika, SARS-CoV-2, and others) human brain diseases. The available data show that (i) disease-specific divergent mechanisms activate the (mainly animal) brains NLRP3; (ii) no evidence proves that NLRP3 inhibition modifies human brain diseases (yet ad hoc trials are ongoing); and (iii) no findings exclude that concurrently activated other-than-NLRP3 inflammasomes might functionally replace the inhibited NLRP3. Finally, we highlight that among the causes of the persistent lack of therapies are the species difference problem in disease models and a preference for symptomatic over etiologic therapeutic approaches. Therefore, we posit that human neural cell-based disease models could drive etiological, pathogenetic, and therapeutic advances, including NLRP3’s and other inflammasomes’ regulation, while minimizing failure risks in candidate drug trials.

CYP1B1-derived epoxides modulate the TRPA1 channel in chronic pain

Pain is often debilitating, and current treatments are neither universally efficacious nor without risks. Transient receptor potential (TRP) ion channels offer alternative targets for pain relief, but little is known about the regulation or identities of endogenous TRP ligands that affect inflammation and pain. Here, transcriptomic and targeted lipidomic analysis of damaged tissue from the mouse spinal nerve ligation (SNL)-induced chronic pain model revealed a time-dependent increase in Cyp1b1 mRNA and a concurrent accumulation of 8,9-epoxyeicosatrienoic acid (EET) and 19,20-EpDPA post injury. Production of 8,9-EET and 19,20-EpDPA by human/mouse CYP1B1 was confirmed in vitro, and 8,9-EET and 19,20-EpDPA selectively and dose-dependently sensitized and activated TRPA1 in overexpressing HEK-293 cells and Trpa1-expressing/AITC-responsive cultured mouse peptidergic dorsal root ganglia (DRG) neurons. TRPA1 activation by 8,9-EET and 19,20-EpDPA was attenuated by the antagonist A967079, and mouse TRPA1 was more responsive to 8,9-EET and 19,20-EpDPA than human TRPA1. This latter effect mapped to residues Y933, G939, and S921 of TRPA1. Intra-plantar injection of 19,20-EpDPA induced acute mechanical, but not thermal hypersensitivity in mice, which was also blocked by A967079. Similarly, Cyp1b1-knockout mice displayed a reduced chronic pain phenotype following SNL injury. These data suggest that manipulation of the CYP1B1-oxylipin-TRPA1 axis might have therapeutic benefit.

2-Methoxyestradiol Ameliorates Angiotensin II-Induced Hypertension by Inhibiting Cytosolic Phospholipase A2α Activity in Female Mice

Supplemental Digital Content is available in the text.

We tested the hypothesis that CYP1B1 (cytochrome P450 1B1)-17β-estradiol metabolite 2-methoxyestradiol protects against Ang II (angiotensin II)–induced hypertension by inhibiting group IV cPLA₂α (cytosolic phospholipase A₂α) activity and production of prohypertensive eicosanoids in female mice. Ang II (700 ng/kg per minute, SC) increased mean arterial blood pressure (BP), systolic and diastolic BP measured by radiotelemetry, renal fibrosis, and reactive oxygen species production in wild-type mice (cPLA₂α^+/+/Cyp1b1^+/+) that were enhanced by ovariectomy and abolished in intact and ovariectomized-cPLA₂α^−/−/Cyp1b1^+/+ mice. Ang II–induced increase in SBP measured by tail-cuff, renal fibrosis, reactive oxygen species production, and cPLA₂α activity measured by its phosphorylation in the kidney, and urinary excretion of prostaglandin E₂ and thromboxane A₂ metabolites were enhanced in ovariectomized-cPLA₂α^+/+/Cyp1b1^+/+ and intact cPLA₂α^+/+/Cyp1b1^−/− mice. 2-Methoxyestradiol and arachidonic acid metabolism inhibitor 5,8,11,14-eicosatetraynoic acid attenuated the Ang II–induced increase in SBP, renal fibrosis, reactive oxygen species production, and urinary excretion of prostaglandin E₂, and thromboxane A₂ metabolites in ovariectomized-cPLA₂α^+/+/Cyp1b1^+/+ and intact cPLA₂α^+/+/Cyp1b1^−/− mice. Antagonists of prostaglandin E₂ and thromboxane A₂ receptors EP1 and EP3 and TP, respectively, inhibited Ang II–induced increases in SBP and reactive oxygen species production and renal fibrosis in ovariectomized-cPLA₂α^+/+/Cyp1b1^+/+ and intact cPLA₂α^+/+/Cyp1b1^−/− mice. These data suggest that CYP1B1-generated metabolite 2-methoxyestradiol mitigates Ang II–induced hypertension and renal fibrosis by inhibiting cPLA₂α activity, reducing prostaglandin E₂, and thromboxane A₂ production and stimulating EP1 and EP3 and TP receptors, respectively. Thus, 2-methoxyestradiol and the drugs that selectively block EP1 and EP3 and TP receptors could be useful in treating hypertension and its pathogenesis in females.

6β-Hydroxytestosterone Promotes Angiotensin II-Induced Hypertension via Enhanced Cytosolic Phospholipase A2α Activity

Supplemental Digital Content is available in the text.

This study was conducted to test the hypothesis that the CYP1B1 (cytochrome P450 1B1)-testosterone metabolite 6β-hydroxytestosterone contributes to angiotensin II-induced hypertension by promoting activation of group IV cPLA₂α (cytosolic phospholipase A₂α) and generation of prohypertensive eicosanoids in male mice. Eight-week-old male intact or orchidectomized cPLA₂α^+/+/Cyp1b1^+/+ and cPLA₂α^–/–/Cyp1b1^+/+ and intact cPLA₂α^+/+/Cyp1b1^–/– mice were infused with angiotensin II (700 ng/kg/min, subcutaneous) for 2 weeks and injected with 6β-hydroxytestosterone (15 μg/g/every third day, intraperitoneal). Systolic blood pressure was measured by tail-cuff and confirmed by radiotelemetry. Angiotensin II-induced increase in systolic blood pressure, cardiac and renal collagen deposition, and reactive oxygen species production were reduced by disruption of the cPLA₂α or Cyp1b1 genes or by administration of the arachidonic acid metabolism inhibitor 5,8,11,14-eicosatetraynoic acid to cPLA₂α^+/+/Cyp1b1^+/+ mice. 6β-hydroxytestosterone treatment restored these effects of angiotensin II in cPLA₂α^+/+/Cyp1b1^–/– mice but not in orchidectomized cPLA₂α^–/–/Cyp1b1^+/+ mice, which were lowered by 5,8,11,14-eicosatetraynoic acid in cPLA₂α^+/+/Cyp1b1^–/– mice. Antagonists of prostaglandin E₂-EP1/EP3 receptors and thromboxane A₂-TP receptors decreased the effect of 6β-hydroxytestosterone in restoring the angiotensin II-induced increase in systolic blood pressure, cardiac and renal collagen deposition, and reactive oxygen species production in cPLA₂α^+/+/Cyp1b1^–/– mice. These data suggest that 6β-hydroxytestosterone promotes angiotensin II-induced increase in systolic blood pressure and associated pathogenesis via cPLA₂α activation and generation of eicosanoids, most likely prostaglandin E₂ and thromboxane A₂ that exerts prohypertensive effects by stimulating EP1/EP3 and TP receptors, respectively. Therefore, agents that selectively block these receptors could be useful in treating testosterone exacerbated angiotensin II-induced hypertension and its pathogenesis.

Biological roles of cytochrome P450 1A1, 1A2, and 1B1 enzymes

Human cytochrome P450 enzymes (CYPs) play a critical role in various biological processes and human diseases. CYP1 family members, including CYP1A1, CYP1A2, and CYP1B1, are induced by aryl hydrocarbon receptors (AhRs). The binding of ligands such as polycyclic aromatic hydrocarbons activates the AhRs, which are involved in the metabolism (including oxidation) of various endogenous or exogenous substrates. The ligands that induce CYP1 expression are reported to be carcinogenic xenobiotics. Hence, CYP1 enzymes are correlated with the pathogenesis of cancers. Various endogenous substrates are involved in the metabolism of steroid hormones, eicosanoids, and other biological molecules that mediate the pathogenesis of several human diseases. Additionally, CYP1s metabolize and activate/inactivate therapeutic drugs, especially, anti-cancer agents. As the metabolism of drugs determines their therapeutic efficacy, CYP1s can determine the susceptibility of patients to some drugs. Thus, understanding the role of CYP1s in diseases and establishing novel and efficient therapeutic strategies based on CYP1s have piqued the interest of the scientific community.