ACE2/ANG-(1-7)/Mas receptor axis activation prevents inflammation and improves cognitive functions in streptozotocin induced rat model of Alzheimer's disease-like phenotypes

The GLP-1 agonist semaglutide ameliorates cognitive regression in P301S tauopathy mice model via autophagy/ACE2/SIRT1/FOXO1-Mediated Microglia Polarization

Tau hyper-phosphorylation has been recognized as an essential contributor to neurodegeneration in Alzheimer's disease (AD) and related tauopathies. In the last decade, tau hyper-phosphorylation has gained considerable concern in AD therapeutic development. Tauopathies are manifested with a broad spectrum of symptoms, from dementia to cognitive decline and motor impairments. Tau undergoes conformational changes and abnormal phosphorylation that mediate its detaching from microtubules, forming neurofibrillary tangles (NFTs). In the current study, a widely used P301S transgenic mice model of tauopathy was employed to evaluate the possible neuroprotective effects of semaglutide as an autophagy regulator through modifications of the brain renin-angiotensin system (RAS). Mice were divided into two groups according to their genotypes (wild type (Wt) and P301S), which were further subdivided to receive either vehicle (saline) or semaglutide (25 nmol/kg, i. p.), once every 2 days for 28 days. Current data suggest that semaglutide ameliorated the hyperactive pattern and alleviated the cognitive decline of P301S mice. It also hastened the autophagic flux through augmenting angiotensin-converting enzyme 2/sirtuin 1/forkhead box protein O1 signaling. Semaglutide also hindered the expression of phosphorylated adenosine monophosphate-activated protein kinase and phosphorylated glycogen synthase kinase-3 beta at serine 9, reducing the propagation of neuroinflammatory cytokines and oxidative reactions. Finally, semaglutide protected against hippocampal degeneration and reduced the immunoreactivity for total tau and ionized calcium-binding adapter molecule. Semaglutide showed promising neuroprotective implications in alleviating tauopathy-related AD's molecular and behavioral deficits through controlling autophagy and brain RAS.

Exploring hypertension-linked diseases: a comprehensive review of innovative drug combinations with enhanced therapeutic potential

Hypertension, a prevalent cardiovascular condition affecting a substantial portion of the global population, remains a formidable health challenge associated with a multitude of complications. This review article provides a comprehensive examination of hypertension, its various complications, and the emergence of a novel management technique that shows promising potential in transforming the therapeutic landscape. Over the years, conventional treatment approaches, encompassing lifestyle modifications, dietary interventions, and pharmacotherapy, have been the mainstay in managing hypertension. However, these strategies fall short in achieving optimal blood pressure control and preventing complications in a significant number of patients. Consequently, the medical community has ventured into exploring innovative management techniques to tackle this unmet medical need. The focal point of this review centers on the emergence of a new management technique for hypertension that exhibits promise in preclinical and clinical studies. The latest research findings shed light on the efficacy and safety of this innovative approach, which encompasses pharmaceutical agents, medical devices, and non-invasive interventions. Through critical analysis and discussion, we explore the potential impact of these novel strategies on hypertension management and patient outcomes. In conclusion, this review article provides a comprehensive overview of hypertension, its complications, and the promising emergence of innovative management techniques. By acknowledging the complexity of hypertension and the potential of new therapeutic avenues, we aspire to pave the way for improved patient care, enhanced quality of life, and ultimately, the mitigation of hypertension-related morbidity and mortality.

Efficacy and safety of dual renin-angiotensin system (RAS) blockade for non-elderly diabetic kidney disease patients with preserved eGFR

AIM

Although sodium glucose cotransporter2 inhibitor (SGLT-2I) is widely used in clinical practice, sufficient renin-angiotensin system (RAS) inhibition remains the cornerstone of diabetic kidney disease (DKD) treatment. The aim of this single-center study was to evaluate the efficacy and safety of dual RAS blockade compared with angiotensin-converting enzyme inhibitor (ACEI)/angiotensin II receptor blocker (ARB) monotherapy in non-elderly DKD patients with preserved eGFR (WHO Standard, < 60y).

METHODS

This single-center study was registered in Chinese Clinical Trial Registry (ChiCTR1900024752), and approved by the ethical committee (KY201994). In this study, we recruited non-elderly type 2 diabetes volunteers with initial diagnosis of DKD to receive dual RAS blockade or monotherapy. 150 non-elderly DKD patients with preserved eGFR were recruited. The patients were randomly divided into dual RAS blockade group and monotherapy group. The dual RAS blockade group treatment regimen was an 80 mg valsartan plus a 4 mg perindopril tert-butylamine per day. At the same time, monotherapy group patients who received the 8 mg perindopril tert-butylamine or 160 mg valsartan monotherapy. The clinical data of the three groups were compared at baseline and collected during the follow-up period of 12 months.

RESULTS

The baseline of patients who received dual RAS blockade was similar to that of monotherapy group. After 12 months of treatment, the median level of proteinuria in the dual RAS blockade group was significantly lower than that in the monotherapy group. There was no significant difference in the estimated glomerular filtration rate (eGFR) level, potassium, blood pressure and no serious adverse reactions.

CONCLUSIONS

In non-elderly DKD patients with preserved eGFR, dual RAS blockade is superior to control proteinuria, and does not increase the probability of adverse reactions such as hyperkalemia, hypotension and acute kidney injury in 12 months.

The Aggravating Role of Failing Neuropeptide Networks in the Development of Sporadic Alzheimer's Disease

Alzheimer's disease imposes an increasing burden on aging Western societies. The disorder most frequently appears in its sporadic form, which can be caused by environmental and polygenic factors or monogenic conditions of incomplete penetrance. According to the authors, in the majority of cases, Alzheimer's disease represents an aggravated form of the natural aging of the central nervous system. It can be characterized by the decreased elimination of amyloid β1-42 and the concomitant accumulation of degradation-resistant amyloid plaques. In the present paper, the dysfunction of neuropeptide regulators, which contributes to the pathophysiologic acceleration of senile dementia, is reviewed. However, in the present review, exclusively those neuropeptides or neuropeptide families are scrutinized, and the authors' investigations into their physiologic and pathophysiologic activities have made significant contributions to the literature. Therefore, the pathophysiologic role of orexins, neuromedins, RFamides, corticotrope-releasing hormone family, growth hormone-releasing hormone, gonadotropin-releasing hormone, ghrelin, apelin, and natriuretic peptides are discussed in detail. Finally, the therapeutic potential of neuropeptide antagonists and agonists in the inhibition of disease progression is discussed here.

Unraveling the role of the renin-angiotensin system in severe mental illnesses: An insight into psychopathology and cognitive deficits

Severe mental illnesses (SMI), especially schizophrenia and bipolar disorder (BD), are associated with significant distress to patients, reduced life expectancy and a higher cost of care. There is growing evidence that SMI may increase the risk of dementia in later life, posing an additional challenge in the management of these patients. SMI present a complex and highly heterogeneous pathophysiology, which has hampered the understanding of its underlying pathological mechanisms and limited the success of the available therapies. Despite the advances in therapeutic approaches in psychiatry over the past decades, treatment resistance is still a common problem in clinical practice, highlighting the urgent need for novel therapeutic targets for SMI. The discovery that renin-angiotensin system (RAS) components are expressed in the central nervous system opened new possibilities for investigating a potential role for this system in the neurobiology of SMI. The safety and efficacy of AT1 receptor blockers and angiotensin-converting enzyme inhibitors in cardiovascular and metabolic diseases, common medical comorbidities among SMI patients and well-known risk factors for dementia, suggest the potential scalability of these strategies for the management of SMI outcomes including the risk of subsequent dementia. This review aimed to discuss the available evidence from animal models and human studies of the potential involvement of RAS in the pathophysiology of SMI. We also provided a reflection on drawbacks and perspectives that can foster the development of new related therapeutic strategies.

Unveiling the Interplay-Vitamin D and ACE-2 Molecular Interactions in Mitigating Complications and Deaths from SARS-CoV-2

The interaction of the SARS-CoV-2 spike protein with membrane-bound angiotensin-converting enzyme-2 (ACE-2) receptors in epithelial cells facilitates viral entry into human cells. Despite this, ACE-2 exerts significant protective effects against coronaviruses by neutralizing viruses in circulation and mitigating inflammation. While SARS-CoV-2 reduces ACE-2 expression, vitamin D increases it, counteracting the virus's harmful effects. Vitamin D's beneficial actions are mediated through complex molecular mechanisms involving innate and adaptive immune systems. Meanwhile, vitamin D status [25(OH)D concentration] is inversely correlated with severity, complications, and mortality rates from COVID-19. This study explores mechanisms through which vitamin D inhibits SARS-CoV-2 replication, including the suppression of transcription enzymes, reduced inflammation and oxidative stress, and increased expression of neutralizing antibodies and antimicrobial peptides. Both hypovitaminosis D and SARS-CoV-2 elevate renin levels, the rate-limiting step in the renin-angiotensin-aldosterone system (RAS); it increases ACE-1 but reduces ACE-2 expression. This imbalance leads to elevated levels of the pro-inflammatory, pro-coagulatory, and vasoconstricting peptide angiotensin-II (Ang-II), leading to widespread inflammation. It also causes increased membrane permeability, allowing fluid and viruses to infiltrate soft tissues, lungs, and the vascular system. In contrast, sufficient vitamin D levels suppress renin expression, reducing RAS activity, lowering ACE-1, and increasing ACE-2 levels. ACE-2 cleaves Ang-II to generate Ang(1-7), a vasodilatory, anti-inflammatory, and anti-thrombotic peptide that mitigates oxidative stress and counteracts the harmful effects of SARS-CoV-2. Excess ACE-2 molecules spill into the bloodstream as soluble receptors, neutralizing and facilitating the destruction of the virus. These combined mechanisms reduce viral replication, load, and spread. Hence, vitamin D facilitates rapid recovery and minimizes transmission to others. Overall, vitamin D enhances the immune response and counteracts the pathological effects of SARS-CoV-2. Additionally, data suggests that widely used anti-hypertensive agents-angiotensin receptor blockers and ACE inhibitors-may lessen the adverse impacts of SARS-CoV-2, although they are less potent than vitamin D.

Activation of angiotensin converting enzyme 2 promotes hippocampal neurogenesis via activation of Wnt/β-catenin signaling in hypertension

Hypertension-induced brain renin-angiotensin system (RAS) activation and neuroinflammation are hallmark neuropathological features of neurodegenerative diseases. Previous studies from our lab have shown that inhibition of ACE/Ang II/AT1R axis (by AT1R blockers or ACE inhibitors) reduced neuroinflammation and accompanied neurodegeneration via up-regulating adult hippocampal neurogenesis. Apart from this conventional axis, another axis of RAS also exists i.e., ACE2/Ang (1-7)/MasR axis, reported as an anti-hypertensive and anti-inflammatory. However, the role of this axis has not been explored in hypertension-induced glial activation and hippocampal neurogenesis in rat models of hypertension. Hence, in the present study, we examined the effect of ACE2 activator, Diminazene aceturate (DIZE) at 2 different doses of 10 mg/kg (non-antihypertensive) and 15 mg/kg (antihypertensive dose) in renovascular hypertensive rats to explore whether their effect on glial activation, neuroinflammation, and neurogenesis is either influenced by blood-pressure. The results of our study revealed that hypertension induced significant glial activation (astrocyte and microglial), neuroinflammation, and impaired hippocampal neurogenesis. However, ACE2 activation by DIZE, even at the low dose prevented these hypertension-induced changes in the brain. Mechanistically, ACE2 activation inhibited Ang II levels, TRAF6-NFκB mediated inflammatory signaling, NOX4-mediated ROS generation, and mitochondrial dysfunction by upregulating ACE2/Ang (1-7)/MasR signaling. Moreover, DIZE-induced activation of the ACE2/Ang (1-7)/MasR axis upregulated Wnt/β-catenin signaling, promoting hippocampal neurogenesis during the hypertensive state. Therefore, our study demonstrates that ACE2 activation can effectively prevent glial activation and enhance hippocampal neurogenesis in hypertensive conditions, regardless of its blood pressure-lowering effects.

Small Intestinal Endocrine Cell Derived Exosomal ACE2 Protects Islet β-Cell Function by Inhibiting the Activation of NLRP3 Inflammasome and Reducing β-Cell Pyroptosis

Background

The "gut-islets axis" is an important endocrine signaling axis that regulates islets function by modulating the gut microbiota and endocrine metabolism within the gut. However, the specific mechanisms and roles of the intestine in islets regulation remain unclear. Recent studies investigated that exosomes derived from gut microbiota can transport signals to remotely regulate islets β-cell function, suggesting the possibility of novel signaling pathways mediated by gut exosomes in the regulation of the "gut-islet axis.".

Methods

The exosomes were isolated from the intestinal enteroendocrine cell-line STC-1cells culture supernatants treated with palmitate acid (PA) or BSA. Metabolic stress models were established by separately subjecting MIN6 cells to PA stimulation and feeding mice with a high-fat diet. Intervention with exosomes in vitro and in vivo to assess the biological effects of exosomes on islets β cells under metabolic stress. The Mas receptor antagonist A779 and ACE2ko mice were used to evaluate the role of exosomal ACE2.

Results

We found ACE2, a molecule that plays a crucial role in the regulation of islets function, is abundantly expressed in exosomes derived from STC-1 under physiological normal condition (NCEO). These exosomes cannot only be taken up by β-cells in vitro but also selectively transported to the islets in vivo. Following intervention with NCEXO, both Min6 cells in a lipotoxic environment and mice on a high-fat diet exhibited significant improvements in islets β-cell function and β-cell mass. Further investigations demonstrated that these protective effects are attributed to exosomal ACE2, as ACE2 inhibits NLRP3 inflammasome activation and reduces β-cell pyroptosis.

Conclusion

ACE2-enriched exosomes from the gut can selectively target islets, subsequently inhibiting NLRP3 inflammasome activation and β cell pyroptosis, thereby restoring islets β cell function under metabolic stress. This study provides novel insights into therapeutic strategies for the prevention and treatment of obesity and diabetes.

ACE2 improves endothelial cell function and reduces acute lung injury by downregulating FAK expression

Endothelial cell (EC) barrier dysfunction and increased adhesion of immune inflammatory cells to ECs crucially contribute to acute lung injury (ALI). Angiotensin-converting enzyme 2 (ACE2) is an essential regulator of the renin-angiotensin system (RAS) and exerts characteristic vasodilatory and anti-inflammatory effects. SARS-COV-2 infects the lungs by binding to ACE2, which can lead to dysregulation of ACE2 expression, further leading to ALI with predominantly vascular inflammation and eventually to more severe acute respiratory distress syndrome (ARDS). Therefore, restoration of ACE2 expression represents a valuable therapeutic approach for SARS-COV-2-related ALI/ARDS. In this study, we used polyinosinic-polycytidylic acid (Poly(I:C)), a double-stranded RNA analog, to construct a mouse ALI model that mimics virus infection. After Poly(I:C) exposure, ACE2 was downregulated in mouse lung tissues and in cultured ECs. Treatment with DIZE, an ACE2-activating compound, upregulated ACE2 expression and relieved ALI in mice. DIZE also improved barrier function and reduced the number of THP-1 monocytes adhering to cultured ECs. Focal adhesion kinase (FAK) and phosphorylated FAK (p-FAK) levels were increased in lung tissues of ALI mice as well as in Poly(I:C)-treated ECs in vitro. Both DIZE and the FAK inhibitor PF562271 decreased FAK/p-FAK expression in both ALI models, attenuating ALI severity in vivo and increasing barrier function and reducing monocyte adhesion in cultured ECs. Furthermore, in vivo experiments using ANG 1-7 and the MAS inhibitor A779 corroborated that DIZE-mediated ACE2 activation stimulated the activity of the ANG 1-7/MAS axis, which inhibited FAK/p-FAK expression in the mouse lung. These findings provide further evidence that activation of ACE2 in ECs may be a valuable therapeutic strategy for ALI.

ACE2 activation alleviates sepsis-induced cardiomyopathy by promoting MasR-Sirt1-mediated mitochondrial biogenesis

Sepsis-induced cardiomyopathy (SIC), caused by a dysregulated host response to infection, is a major contributor to high mortality. Angiotensin-converting enzyme 2 (ACE2), a crucial component of the renin-angiotensin system (RAS), has protective effects against several cardiovascular diseases, such as myocardial infarction and heart failure. However, the role of ACE2 in the pathogenesis of SIC and underlying mechanisms remain unknown. The present study was designed to examine the effects of ACE2 activation or inhibition on SIC in C57BL/6 mice. The ACE2 activator diminazene aceturate (DIZE) and ACE2 inhibitor MLN-4760 were applied for treatment. Myocardial function, inflammatory response, oxidative stress, apoptosis and mitochondrial biogenesis were investigated. Major assays were echocardiography, H&E staining, immunofluorescence staining, DHE staining, TUNEL staining, Western blot, qPCR analysis, ELISA and corresponding kits. We confirmed that ACE2 was markedly downregulated in septic heart tissues. Pharmacological activation of ACE2 by DIZE ameliorated cecal ligation puncture (CLP)-induced mortality, cardiac dysfunction, inflammatory response, oxidative stress and the cardiomyocyte apoptosis by promoting MasR-Sirt1-mediated mitochondrial biogenesis. In contrast, SIC was aggravated via inhibiting MasR-Sirt1-mediated mitochondrial biogenesis by the use of ACE2 inhibitor MLN-4760. Consequently, activation of ACE2 may protect against SIC by promoting MasR-Sirt1-mediated mitochondrial biogenesis.

Potential molecular pathways of angiotensin receptor blockers in the brain toward cognitive improvement in dementia

The alarming rise of cognitive impairment and memory decline and limited effective solutions present a worldwide concern for dementia patients. The multivariant role of the renin-angiotensin system (RAS) in the brain offers strong evidence of a role for angiotensin receptor blockers (ARBs) in the management of memory impairment by modifying glutamate excitotoxicity, downregulating inflammatory cytokines such as interleukin (IL)-1β, IL-6 and tumor necrosis factor (TNF)α, inhibiting kynurenine aminotransferase (KAT)-II, nucleotide-binding domain, leucine-rich-containing family and pyrin-domain-containing-3 (NLRP3) inflammasomes, boosting cholinergic activity, activating peroxisome proliferator-activated receptor (PPAR)-γ, countering cyclooxygenase (COX) and mitigating the hypoxic condition. The present work focuses on the intricate molecular mechanisms involved in brain-RAS, highlighting the role of ARBs, connecting links between evidence-based unexplored pathways and investigating probable biomarkers involved in dementia through supported preclinical and clinical literature.