Candesartan ameliorates brain inflammation associated with Alzheimer's disease

Microglial AT1R Conditional Knockout Ameliorates Hypoperfusive Cognitive Impairment by Reducing Microglial Inflammatory Responses

Chronic cerebral hypoperfusion (CCH) can cause vascular cognitive impairment and dementia. AT1R, angiotensin II type I receptor, plays a vital role in central nervous system pathologies, but its concrete function in vascular dementia is still unclear. Herein, we investigated the effects of AT1R during CCH by conditional knockout of the microglial AT1R and candesartan treatment. Using the bilateral carotid artery stenosis (BCAS) model, we found that the AT1R is crucial in exacerbating CCH-induced cognitive impairment via regulating microglial activation. The levels of AT1R were increased in the hippocampus and the hippocampal microglia after CCH induction. Microglial AT1R conditional knockout ameliorated cognitive impairment by reducing inflammatory responses and microglial activation, and so did candesartan treatment. However, we observed restoration of cerebral blood flow (CBF) but no significant neuronal loss in the hippocampus at 28 days after BCAS. Finally, we screened three hub genes (Ctss, Fcer1g, Tyrobp) associated with CCH. Our findings indicated that microglial expression of AT1R is critical for regulating neuroinflammation in CCH, and AT1R antagonism may be a feasible and promising method for ameliorating CCH-caused cognitive impairment.

Improvement effects of cyclic peptides from Annona squamosa on cognitive decline in neuroinflammatory mice

Cyclic peptides can resist enzymatic hydrolysis to pass through the intestine barrier, which may reduce the risk of mild cognition decline. But evidence is lacking on whether they work by alleviating neuroinflammation. A cylic peptide from Annona squamosa, Cylic(PIYAG), was biologically evaluated in vivo and in vitro. Cylic(PIYAG) enhanced the spatial memory ability of LPS-induced mice. And treatment with Cylic(PIYAG) markedly reduced the iNOS, MCP-1, TNF-α, and gp91phox expression induced by LPS. Cylic(PIYAG, 0.01, 0.05 and 0.2 μM) could significantly reduce the protein expression level of COX-2 and iNOS (P < 0.05) in BV2 cells. The concentration of Cylic(PIYAG) in blood reached a peak of 3.64 ± 1.22 μg/ml after intragastric administration in 1 h. And fluorescence microscope shows that Cylic(PIYAG) mainly locates and may play an anti-inflammatory role in the cytoplasm of microglia. This study demonstrates that the peptidic can prevent microglia activation, decrease the inflammatory reaction, improve the cognition of LPS-induced mice.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-023-01441-8.

New Perspectives for Antihypertensive Sartans as Components of Co-crystals and Co-amorphous Solids with Improved Properties and Multipurpose Activity

Sartans (angiotensin II receptor blockers, ARBs), drugs used in the treatment of hypertension, play a principal role in addressing the global health challenge of hypertension. In the past three years, their potential use has expanded to include the possibility of their application in the treatment of COVID-19 and neurodegenerative diseases (80 clinical studies worldwide). However, their therapeutic efficacy is limited by their poor solubility and bioavailability, prompting the need for innovative approaches to improve their pharmaceutical properties. This review discusses methods of co-crystallization and co-amorphization of sartans with nonpolymeric, low molecular, and stabilizing co-formers, as a promising strategy to synthesize new multipurpose drugs with enhanced pharmaceutical properties. The solid-state forms have demonstrated the potential to address the poor solubility limitations of conventional sartan formulations and offer new opportunities to develop dual-active drugs with broader therapeutic applications. The review includes an in-depth analysis of the co-crystal and co-amorphous forms of sartans, including their properties, possible applications, and the impact of synthetic methods on their pharmacokinetic properties. By shedding light on the solid forms of sartans, this article provides valuable insights into their potential as improved drug formulations. Moreover, this review may serve as a valuable resource for designing similar solid forms of sartans and other drugs, fostering further advances in pharmaceutical research and drug development.

Effect of safranal or candesartan on 3-nitropropionicacid-induced biochemical, behavioral and histological alterations in a rat model of Huntington's disease

3-nitropropionic acid (3-NP) is a potent mitochondrial inhibitor mycotoxin. Systemic administration of 3-NP can induce Huntington's disease (HD)-like symptoms in experimental animals. Safranal (Safr) that is found in saffron essential oil has antioxidant, anti-inflammatory and anti-apoptotic actions. Candesartan (Cands) is an angiotensin receptor blocker that has the potential to prevent cognitive deficits. The present study aims to investigate the potential neuroprotective efficacy of Safr or Cands in 3-NP-induced rat model of HD. The experiments continued for nine consecutive days. Rats were randomly assigned into seven groups. The first group (Safr-control) was daily intraperitoneally injected with paraffin oil. The second group (Cands- and 3-NP-control) daily received an oral dose of 0.5% carboxymethylcellulose followed by an intraperitoneal injection of 0.9% saline. The third and fourth groups received a single daily dose of 50 mg/kg Safr (intraperitoneal) and 1 mg/kg Cands (oral), respectively. The sixth group was daily treated with 50 mg Safr kg/day (intraperitoneal) and was intraperitoneally injected with 20 mg 3-NP/ kg, from the 3rd till the 9th day. The seventh group was daily treated with 1 mg Cands /kg/day (oral) and was intraperitoneally injected with 20 mg 3-NP/ kg, from the 3rd till the 9th day. The present results revealed that 3-NP injection induced a considerable body weight loss, impaired memory and locomotor activity, reduced striatal monoamine levels. Furthermore, 3-NP administration remarkably increased striatal malondialdehyde and nitric oxide levels, whereas markedly decreased the total antioxidant capacity. Moreover, 3-NP significantly upregulated the activities of inducible nitric oxide synthase and caspase-3 as well as the Fas ligand, in striatum. On the contrary, Safr and Cands remarkably alleviated the above-mentioned 3-NP-induced alterations. In conclusion, Safr and Cands may prevent or delay the progression of HD and its associated impairments through their antioxidant, anti-inflammatory, anti-apoptotic and neuromodulator effects.

Therapeutic Implications of Renin-Angiotensin System Modulators in Alzheimer's Dementia

The Renin-Angiotensin System (RAS) has attracted considerable interest beyond its traditional cardiovascular role due to emerging data indicating its potential involvement in neurodegenerative diseases, including Alzheimer's dementia (AD). This review investigates the therapeutic implications of RAS modulators, specifically focusing on angiotensin-converting enzyme inhibitors (ACEIs), angiotensin receptor blockers (ARBs), and renin inhibitors in AD. ACEIs, commonly used for hypertension, show promise in AD by reducing angiotensin (Ang) II levels. This reduction is significant as Ang II contributes to neuroinflammation, oxidative stress, and β-amyloid (Aβ) accumulation, all implicated in AD pathogenesis. ARBs, known for vasodilation, exhibit neuroprotection by blocking Ang II receptors, improving cerebral blood flow and cognitive decline in AD models. Renin inhibitors offer a novel approach by targeting the initial RAS step, displaying anti-inflammatory and antioxidant effects that mitigate AD degeneration. Preclinical studies demonstrate RAS regulation's favorable impact on neuroinflammation, neuronal damage, cognitive function, and Aβ metabolism. Clinical trials on RAS modulators in AD are limited, but with promising results, ARBs being more effective that ACEIs in reducing cognitive decline. The varied roles of ACEIs, ARBs, and renin inhibitors in RAS modulation present a promising avenue for AD therapeutic intervention, requiring further research to potentially transform AD treatment strategies.

Comparative Study of Safety and Efficacy of Angiotensin-Receptor Blockers and Anti Amyloid-ß Monoclonal Antibodies for the Treatment of Alzheimer's Disease: A Systematic Review

Amyloid-ß (Aß) plaques and Neurofibrillary tangles are hallmarks of Alzheimer's disease (AD) pathology. Recent advances to find a cure for AD have led to the exploration of Anti-Aß monoclonal antibodies and angiotensin-receptor blockers (ARBs). The antibodies can decrease plaque formation or remove already formed plaques. ARBs increase angiotensin II (AT2) levels and decrease the effect of AT2 on the AT1 receptor (AT1R). This systematic analysis reviews evidence of monoclonal antibodies (Aducanumab, Lecanemab, Donanemab, and Solanezumab) and ARBs in managing AD. An in-depth methodical search was conducted across PubMed, Science Direct, and Mendeley. PRISMA 2020 guidelines were followed for this study. Randomized control trials for antibodies and ARBs and one retrospective cohort study were included. The comparison was made among studies that shared similar measured outcomes. Antibodies were found to be more effective than ARBs, with Aducanumab and Lecanemab being the most effective. ARBs, on the other hand, were found to be the safer choice. Further trials of longer duration and larger sample sizes are needed to explore both groups' long-term safety and efficacy.

Pomegranate peel extract protects against the development of diabetic cardiomyopathy in rats by inhibiting pyroptosis and downregulating LncRNA-MALAT1

Background: Pyroptosis is an inflammatory programmed cell death accompanied by activation of inflammasomes and maturation of pro-inflammatory cytokines interleukin-1β (IL-1β) and IL-18. Pyroptosis is closely linked to the development of diabetic cardiomyopathy (DC). Pomegranate peel extract (PPE) exhibits a cardioprotective effect due to its antioxidant and anti-inflammatory properties. This study aimed to investigate the underlying mechanisms of the protective effect of PPE on the myocardium in a rat model of DC and determine the underlying molecular mechanism.

Methods: Type 1 diabetes (T1DM) was induced in rats by intraperitoneal injection of streptozotocin. The rats in the treated groups received (150 mg/kg) PPE orally and daily for 8 weeks. The effects on the survival rate, lipid profile, serum cardiac troponin-1, lipid peroxidation, and tissue fibrosis were assessed. Additionally, the expression of pyroptosis-related genes (NLRP3 and caspase-1) and lncRNA-MALAT1 in the heart tissue was determined. The PPE was analyzed using UPLC-MS/MS and NMR for characterizing the phytochemical content.

Results: Prophylactic treatment with PPE significantly ameliorated cardiac hypertrophy in the diabetic rats and increased the survival rate. Moreover, prophylactic treatment with PPE in the diabetic rats significantly improved the lipid profile, decreased serum cardiac troponin-1, and decreased lipid peroxidation in the myocardial tissue. Histopathological examination of the cardiac tissues showed a marked reduction in fibrosis (decrease in collagen volume and number of TGF-β-positive cells) and preservation of normal myocardial structures in the diabetic rats treated with PPE. There was a significant decrease in the expression of pyroptosis-related genes (NLRP3 and caspase-1) and lncRNA-MALAT1 in the heart tissue of the diabetic rats treated with PPE. In addition, the concentration of IL-1β and caspase-1 significantly decreased in the heart tissue of the same group. The protective effect of PPE on diabetic cardiomyopathy could be due to the inhibition of pyroptosis and downregulation of lncRNA-MALAT1. The phytochemical analysis of the PPE indicated that the major compounds were hexahydroxydiphenic acid glucoside, caffeoylquinic acid, gluconic acid, citric acid, gallic acid, and punicalagin.

Conclusion: PPE exhibited a cardioprotective potential in diabetic rats due to its unique antioxidant, anti-inflammatory, and antifibrotic properties and its ability to improve the lipid profile. The protective effect of PPE on DC could be due to the inhibition of the NLRP3/caspase-1/IL-1β signaling pathway and downregulation of lncRNA-MALAT1. PPE could be a promising therapy to protect against the development of DC, but further clinical studies are recommended.

Role of angiotensin receptor blockers in the context of Alzheimer's disease

As the world's population ages, the prevalence of age-related neurological disorders such as Alzheimer's disease (AD) is increasing. There is currently no treatment for Alzheimer's disease, and the few approved medications have a low success rate in lowering symptoms. As a result, several attempts are underway worldwide to identify new targets for the therapy of Alzheimer's disease. In preclinical studies of Alzheimer's disease, it was recently found that inhibition of angiotensin-converting enzyme (ACE) and blocking of the angiotensin II receptors reduce symptoms of neurodegeneration, Aβ plaque development, and tau hyperphosphorylation. Angiotensin II type I (AT1) blockers, such as telmisartan, candesartan, valsartan, and others, have a wide safety margin and are commonly used to treat hypertension. Renal and cardiovascular failures are reduced due to their vascular protective actions. Inhibition of AT1 receptors in the brain has a neuroprotective impact in humans, reducing the risk of stroke, increasing cognition, and slowing the progression of Alzheimer's disease. The review focuses on the mechanisms via which AT1 blockers may act beneficially in Alzheimer's disease. Although their effect is evident in preclinical studies, clinical trials, on the other hand, are in short supply to validate the strategy. More dose-response experiments with possible AT1 blockers and brain-targeted administration will be needed in the future.

Deciphering mechanisms of action of ACE inhibitors in neurodegeneration using Drosophila models of Alzheimer's disease

Alzheimer's disease (AD) is a devastating neurodegenerative disorder for which there is no cure. Recently, several studies have reported a significant reduction in the incidence and progression of dementia among some patients receiving antihypertensive medications such as angiotensin-converting enzyme inhibitors (ACE-Is) and angiotensin receptor blockers (ARBs). Why these drugs are beneficial in some AD patients and not others is unclear although it has been shown to be independent of their role in regulating blood pressure. Given the enormous and immediate potential of ACE-Is and ARBs for AD therapeutics it is imperative that we understand how they function. Recently, studies have shown that ACE-Is and ARBs, which target the renin angiotensin system in mammals, are also effective in suppressing neuronal cell death and memory defects in Drosophila models of AD despite the fact that this pathway is not conserved in flies. This suggests that the beneficial effects of these drugs may be mediated by distinct and as yet, identified mechanisms. Here, we discuss how the short lifespan and ease of genetic manipulations available in Drosophila provide us with a unique and unparalleled opportunity to rapidly identify the targets of ACE-Is and ARBs and evaluate their therapeutic effectiveness in robust models of AD.

Multipronged diagnostic and therapeutic strategies for Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder and a major contributor to dementia cases worldwide. AD is clinically characterized by learning, memory, and cognitive deficits. The accumulation of extracellular amyloid β (Aβ) plaques and neurofibrillary tangles (NFTs) of tau are the pathological hallmarks of AD and are explored as targets for clinical diagnosis and therapy. AD pathology is poorly understood and there are no fully approved diagnosis and treatments. Notwithstanding the gap, decades of research in understanding disease mechanisms have revealed the multifactorial nature of AD. As a result, multipronged and holistic approaches are pertinent to targeting multiple biomarkers and targets for developing effective diagnosis and therapeutics. In this perspective, recent developments in Aβ and tau targeted diagnostic and therapeutic tools are discussed. Novel indirect, combination, and circulating biomarkers as potential diagnostic targets are highlighted. We underline the importance of multiplexing and multimodal detection of multiple biomarkers to generate biomarker fingerprints as a reliable diagnostic strategy. The classical therapeutics targeting Aβ and tau aggregation pathways are described with bottlenecks in the strategy. Drug discovery efforts targeting multifaceted toxicity involving protein aggregation, metal toxicity, oxidative stress, mitochondrial damage, and neuroinflammation are highlighted. Recent efforts focused on multipronged strategies to rationally design multifunctional modulators targeting multiple pathological factors are presented as future drug development strategies to discover potential therapeutics for AD.

RENEWAL: REpurposing study to find NEW compounds with Activity for Lewy body dementia-an international Delphi consensus

Drug repositioning and repurposing has proved useful in identifying new treatments for many diseases, which can then rapidly be brought into clinical practice. Currently, there are few effective pharmacological treatments for Lewy body dementia (which includes both dementia with Lewy bodies and Parkinson's disease dementia) apart from cholinesterase inhibitors. We reviewed several promising compounds that might potentially be disease-modifying agents for Lewy body dementia and then undertook an International Delphi consensus study to prioritise compounds. We identified ambroxol as the top ranked agent for repurposing and identified a further six agents from the classes of tyrosine kinase inhibitors, GLP-1 receptor agonists, and angiotensin receptor blockers that were rated by the majority of our expert panel as justifying a clinical trial. It would now be timely to take forward all these compounds to Phase II or III clinical trials in Lewy body dementia.

Angiotensin II receptor type 1 blocker candesartan improves morphine tolerance by reducing morphine‑induced inflammatory response and cellular activation of BV2 cells via the PPARγ/AMPK signaling pathway

Morphine is the most common drug of choice in clinical pain management; however, morphine tolerance presents a significant clinical challenge. The pathogenesis of morphine tolerance is known to be closely associated with angiotensin II receptor type 1 (AT1R) in microglia. As an AT1R antagonist, candesartan may serve an important role in regulating morphine tolerance. Therefore, the present study aimed to investigate the role of candesartan in morphine tolerance, and to explore the underlying mechanism. To meet this aim, BV2 microglial cells were treated with morphine or candesartan alone, or as a combination, and the expression levels of AT1R in BV2 cells were detected by reverse transcription‑quantitative PCR (RT‑qPCR) and western blotting. The levels of the inflammatory cytokines tumor necrosis factor‑α, interleukin (IL)‑1β and IL‑6 were subsequently detected by ELISA and western blotting. In addition, immunofluorescence analysis, western blotting and RT‑qPCR were used to detect the expression levels of the BV2 cell activation marker, ionized calcium‑binding adaptor molecule 1 (IBA‑1). Western blotting was also used to detect the expression levels of peroxisome proliferator‑activated receptor‑γ/AMP‑activated protein kinase (PPARγ/AMPK) signaling pathway‑associated proteins. Finally, the cells were treated with the PPARγ antagonist GW9662 and the AMPK inhibitor compound C to further explore the mechanism underlying the effects of candesartan on improving morphine tolerance. The expression levels of AT1R were revealed to be significantly increased following morphine induction; however, candesartan treatment inhibited the expression levels of AT1R, the levels of inflammatory cytokines and the protein expression levels of IBA‑1 in morphine‑induced BV2 cells in a dose‑dependent manner. These processes may be associated with activation of the PPARγ/AMPK signaling pathway. Taken together, the present study revealed that treatment with candesartan reduced morphine‑induced inflammatory response and cellular activation of BV2 cells via PPARγ/AMPK signaling.

Migraine Pharmacological Treatment and Cognitive Impairment: Risks and Benefits

Migraine is a common neurological disorder impairing the quality of life of patients. The condition requires, as an acute or prophylactic line of intervention, the frequent use of drugs acting on the central nervous system (CNS). The long-term impact of these medications on cognition and neurodegeneration has never been consistently assessed. The paper reviews pharmacological migraine treatments and discusses their biological and clinical effects on the CNS. The different anti-migraine drugs show distinct profiles concerning neurodegeneration and the risk of cognitive deficits. These features should be carefully evaluated when prescribing a pharmacological treatment as many migraineurs are of scholar or working age and their performances may be affected by drug misuse. Thus, a reconsideration of therapy guidelines is warranted. Furthermore, since conflicting results have emerged in the relationship between migraine and dementia, future studies must consider present and past pharmacological regimens as potential confounding factors.

The immunomodulatory effects of antihypertensive therapy: A review

Hypertension remains the leading preventable risk factor for stroke and coronary artery disease, significantly contributing to all-cause global mortality and predisposing patients to renal and heart failure, as well as peripheral vascular disease. Due to the widespread usage of antihypertensive drugs, global mean blood pressure has remained unchanged or even slightly decreased over the past four decades. However, considering the broad spectrum of mechanisms involved in the action of antihypertensive drugs and the prevalence of their target receptors on immune cells, possible immunomodulatory effects which may exert beneficial effects of lowering blood pressure but also potentially alter immune function should be considered. In this review, we attempt to assess the consequences to immune system function of administering the five most commonly prescribed groups of antihypertensive drugs and to explain the mechanisms behind those interactions. Finally, we show potential gaps in our understanding of the effects of antihypertensive drugs on patient health. With regard to the widespread use of these drugs in the adult population worldwide, the discussed results may be of vital importance to evidence-based decision-making in daily clinical practice.

Repositioning of the Angiotensin II Receptor Antagonist Candesartan as an Anti-Inflammatory Agent With NLRP3 Inflammasome Inhibitory Activity

Aberrant activation of the NLRP3 inflammasome promotes the pathogenesis of many inflammatory diseases. The development of the NLRP3 inflammasome inhibitors from existing drugs for new therapeutic purposes is becoming more important. Candesartan is an angiotensin II receptor antagonist widely used as a blood pressure-lowering drug; however, the inhibitory potential of candesartan on the NLRP3 inflammasome has not yet been investigated. We demonstrated that candesartan significantly inhibited the NLRP3 inflammasome and pyroptosis in macrophages. Mechanistic analysis revealed that candesartan inhibited the expression of NLRP3 and proIL-1β by suppressing NF-κB activation and reducing the phosphorylation of ERK1/2 and JNK1/2. Candesartan reduced mitochondrial damage and inhibited the NLRP3 inflammasome assembly by suppressing NLRP3 binding to PKR, NEK7 and ASC. In addition, candesartan inhibited IL-1β secretion partially through autophagy induction. Furthermore, oral administration of candesartan reduced peritoneal neutrophil influx, NLRP3 and ASC expression in peritoneal cells, and lavage fluid concentrations of active caspase-1, IL-1β, IL-6 and MCP-1 in uric acid crystal-injected mice. These results indicated that candesartan has board anti-inflammatory effects and has the potential to be repositioned to ameliorate inflammatory diseases or NLRP3-associated complications.

Mechanistic Insights for Drug Repurposing and the Design of Hybrid Drugs for Alzheimer's Disease

The heterogeneity and complex nature of Alzheimer's disease (AD) is attributed to several genetic risk factors and molecular culprits. The slow pace and increasing failure rate of conventional drug discovery has led to the exploration of complementary strategies based on repurposing approved drugs to treat AD. Drug repurposing (DR) is a cost-effective, low-risk, and efficient approach for identifying novel therapeutic candidates for AD treatment. Similarly, hybrid drug design through the integration of distinct pharmacophores from known or failed drugs and natural products is an interesting strategy to target the multifactorial nature of AD. In this Perspective, we discuss the potential of DR and highlight promising drug candidates that can be advanced for clinical trials, backed by a detailed discussion on their plausible mechanisms of action. Our article fosters research on the hidden potential of DR and hybrid drug design with the goal of unravelling new drugs and targets to tackle AD.

New Paradigm in Cell Therapy Using Sperm Head to Restore Brain Function and Structure in Animal Model of Alzheimer’s Disease: Support for Boosting Constructive Inflammation vs. Anti-Inflammatory Approach

Alzheimer’s is characterized by accumulation of amyloid-β (Aβ) associated with insufficient clearance of toxicants from the brain establishing a chronic inflammation and other abnormalities in the brain. Inflammatory microglia and astrocytes along with abnormal lymphatics associated with insufficient clearance of Aβ and other toxicants from the brain establish a chronic inflammation. This causes abnormal choroid plexus, leukocyte trafficking, and hypoxic condition along with high levels of regulatory T cells (Tregs). There is no consensus among researchers regarding decreasing or increasing Tregs to achieve therapeutic effects. Different opposing studies tried to suppress or boost inflammation to treat AD. Based on reproductive immunology, sperm induces constructive inflammatory response and seminal-vesicle-fluid (SVF) suppresses inflammation leading to uterus remodeling. It prompted us to compare therapeutic efficiency of inflammatory or anti-inflammatory approaches in AD model based on reproductive immunology. To do so, SVF, sperm, or sperm head (from Wistar rat) was administered via intra-cerebro-ventricular route to Sprague Dawley rat AD model. Behavioral and histological examination were made and treatment groups were compared with control AD model and normal groups. Therapeutic efficacy was in the order of sperm head>sperm>SVF. Sperm head returned learning memory, Aβ, lymphatics, neural growth factors, choroid plexus function, Iba-1/GFAP, MHC II/CD86/CD40, CD38/IL-10, and hypoxia levels back to normal level. However, SVF just partially ameliorated the disease. Immunologic properties of sperm/sperm head to elicit constructive inflammation can be extended to organs other than reproductive. This nature-based approach overcomes genetic difference as an important obstacle and limitation in cell therapy, and is expected to be safe or with least side effects.

Microglia Polarization From M1 to M2 in Neurodegenerative Diseases

Microglia-mediated neuroinflammation is a common feature of neurodegenerative diseases such as Alzheimer’s disease (AD), Parkinson’s disease (PD), amyotrophic lateral sclerosis (ALS), and multiple sclerosis (MS). Microglia can be categorized into two opposite types: classical (M1) or alternative (M2), though there’s a continuum of different intermediate phenotypes between M1 and M2, and microglia can transit from one phenotype to another. M1 microglia release inflammatory mediators and induce inflammation and neurotoxicity, while M2 microglia release anti-inflammatory mediators and induce anti-inflammatory and neuroprotectivity. Microglia-mediated neuroinflammation is considered as a double-edged sword, performing both harmful and helpful effects in neurodegenerative diseases. Previous studies showed that balancing microglia M1/M2 polarization had a promising therapeutic prospect in neurodegenerative diseases. We suggest that shifting microglia from M1 to M2 may be significant and we focus on the modulation of microglia polarization from M1 to M2, especially by important signal pathways, in neurodegenerative diseases.

Neuroinflammation: A Potential Risk for Dementia

Dementia is a neurodegenerative condition that is considered a major factor contributing to cognitive decline that reduces independent function. Pathophysiological pathways are not well defined for neurodegenerative diseases such as dementia; however, published evidence has shown the role of numerous inflammatory processes in the brain contributing toward their pathology. Microglia of the central nervous system (CNS) are the principal components of the brain’s immune defence system and can detect harmful or external pathogens. When stimulated, the cells trigger neuroinflammatory responses by releasing proinflammatory chemokines, cytokines, reactive oxygen species, and nitrogen species in order to preserve the cell’s microenvironment. These proinflammatory markers include cytokines such as IL-1, IL-6, and TNFα chemokines such as CCR3 and CCL2 and CCR5. Microglial cells may produce a prolonged inflammatory response that, in some circumstances, is indicated in the promotion of neurodegenerative diseases. The present review is focused on the involvement of microglial cell activation throughout neurodegenerative conditions and the link between neuroinflammatory processes and dementia.

SK-Channel Activation Alters Peripheral Metabolic Pathways in Mice, but Not Lipopolysaccharide-Induced Fever or Inflammation

Purpose

Previously, we have shown that CyPPA (cyclohexyl-[2-(3,5-dimethyl-pyrazol-1-yl)-6-methyl-pyrimidin-4-yl]-amine), a pharmacological small-conductance calcium-activated potassium (SK)–channel positive modulator, antagonizes lipopolysaccharide (LPS)-induced cytokine expression in microglial cells. Here, we aimed to test its therapeutic potential for brain-controlled sickness symptoms, brain inflammatory response during LPS-induced systemic inflammation, and peripheral metabolic pathways in mice.

Methods

Mice were pretreated with CyPPA (15 mg/kg IP) 24 hours before and simultaneously with LPS stimulation (2.5 mg/kg IP), and the sickness response was recorded by a telemetric system for 24 hours. A second cohort of mice were euthanized 2 hours after CyPPA or solvent treatment to assess underlying CyPPA-induced mechanisms. Brain, blood, and liver samples were analyzed for inflammatory mediators or nucleotide concentrations using immunohistochemistry, real-time PCR and Western blot, or HPLC. Moreover, we investigated CyPPA-induced changes of UCP1 expression in brown adipose tissue (BAT)–explant cultures.

Results

CyPPA treatment did not affect LPS-induced fever, anorexia, adipsia, or expression profiles of inflammatory mediators in the hypothalamus or plasma or microglial reactivity to LPS (CD11b staining and CD68 mRNA expression). However, CyPPA alone induced a rise in core body temperature linked to heat production via altered metabolic pathways like reduced levels of adenosine, increased protein content, and increased UCP1 expression in BAT-explant cultures, but no alteration in ATP/ADP concentrations in the liver. CyPPA treatment was accompanied by altered pathways, including NFκB signaling, in the hypothalamus and cortex, while circulating cytokines remained unaltered.

Conclusion

Overall, while CyPPA has promise as a treatment strategy, in particular according to results from in vitro experiments, we did not reveal anti-inflammatory effects during severe LPS-induced systemic inflammation. Interestingly, we found that CyPPA alters metabolic pathways inducing short hyperthermia, most likely due to increased energy turnover in the liver and heat production in BAT.

Candesartan protects against d-galactose induced - Neurotoxicity and memory deficit via modulation of autophagy and oxidative stress

PURPOSE

d-galactose induces neuroinflammation and memory deficit via oxidative stress. Candesartan is an angiotensin II-receptor blocker and has proved neuroprotective properties. This study aimed to investigate the neuroprotective effect of candesartan against d-galactose induced neuroinflammation and memory deficit via autophagy.

METHODS

Twenty-eight male Wistar rats aged 3 months were divided into four equal groups: control (vehicle), d-gal (100 mg/kg d-galactose), cand (1 mg/kg candesartan), and cand+d-gal (100 mg/kg d-galactose & 1 mg/kg candesartan). All treatments were given orally and daily for 4 weeks. Assessment of memory was done using Morris water maze (MWM) test. Brain tissue was assessed for malondialdehyde (MDA), total thiol, catalase activity, glial fibrillary acidic protein (GFAP) and gene expression of TNF-α, GDNF-1 as well as autophagy genes (Beclin 1 and ATG 5).

RESULTS

Prophylactic treatment of candesartan in d-galactose-treated rats significantly (p < 0.001) reduced oxidative stress via reduction of MDA as well as elevation of catalase activity and total thiol levels. Additionally, candesartan prophylactic treatment significantly increased gene expression of GDNF-1 and decreased gene expression of TNF-α. Furthermore, candesartan significantly increased the expression of autophagy related gene (Beclin 1 and ATG 5) in cand+d-gal treated rats. These results were supported by the histopathological findings which showed that candesartan prevented the neuronal injury in the cerebral cortex and hippocampus and decreased GFAP positive cells of the d-galactose-treated rats. Moreover, MWM test showed that candesartan significantly improved memory deficit in cand+d-gal treated rats.

CONCLUSION

Candesartan prevents d-galactose-induced neurotoxicity and memory deficit via activating autophagy and decreasing oxidative stress. Therefore, candesartan was a good candidate for age-related neurodegenerative disorders and memory deficit.

Recent advances in molecular pathways and therapeutic implications targeting neuroinflammation for Alzheimer's disease

Alzheimer's disease (AD) is a major contributor of dementia leading to the degeneration of neurons in the brain with major symptoms like loss of memory and learning. Many evidences suggest the involvement of neuroinflammation in the pathology of AD. Cytokines including TNF-α and IL-6 are also found increasing the BACE1 activity and expression of NFκB resulting in generation of Aβ in AD brain. Following the interaction of Aβ with microglia and astrocytes, other inflammatory molecules also get translocated to the site of inflammation by chemotaxis and exaggerate neuroinflammation. Various pathways like NFκB, p38 MAPK, Akt/mTOR, caspase, nitric oxide and COX trigger microglia to release inflammatory cytokines. PPARγ agonists like pioglitazone increases the phagocytosis of Aβ and reduces inflammatory cytokine IL-1β. Celecoxib and roficoxib like selective COX-2 inhibitors also ameliorate neuroinflammation. Non-selective COX inhibitor indomethacin is also potent inhibitor of inflammatory mediators released from microglia. Mitophagy process is considered quite helpful in reducing inflammation due to microglia as it promotes the phagocytosis of over activated microglial cells and other inflammatory cells. Mitophagy induction is also beneficial in the removal of damaged mitochondria and reduction of infiltration of inflammatory molecules at the site of accumulation of the damaged mitochondria. Targeting these pathways and eventually ameliorating the activation of microglia can mitigate neuroinflammation and come out as a better therapeutic option for the treatment of Alzheimer's disease.

Hydrophilic polymer driven crystallization self-assembly: an inflammatory multi-drug combination nanosystem against Alzheimer's disease

The hydrophobic polymer driven crystallization of self-assembled micelles is usually sufficient for their purposes in materials chemistry studies. However, with the state of smart drug delivery research, micelles alone are not enough. The principles of the self assembly driven by hydrophilic dextran brushes together with charged poly(3-acrylamidophenyl boronic acid) (PPBA) are uncovered in this study. A series of poly(ε-caprolactone)-block-poly(3-acrylamidophenyl boronic acid)-dextran (PCL-b-PPBA-Dex) micelles and vesicles are investigated as potential Alzheimer's disease (AD) treatments. Three inflammatory microenvironment responsive micelles, including celecoxib drug-loaded micelles (CEL), ibuprofen drug-loaded micelles (IBU) and telmisartan drug-loaded micelles (TEL), are developed. In vivo, CEL/IBU (mixture of CEL and IBU) and CEL/TEL (mixture of CEL and TEL) suppress the activation of glia and reduce the levels of inflammatory mediators through eliminating cyclooxygenase 2 (COX-2) signals. The CEL/TEL combination nanosystem is better at correcting neuroinflammation and improving the spatial memory ability of a senescence-accelerated mouse prone 8 model (SAMP8). We consider that the inflammation responsive combination nanosystem provides a new potential treatment for AD clinical patients.

Manifestation of renin angiotensin system modulation in traumatic brain injury

Traumatic brain injury (TBI) alters brain function and is a crucial public health concern worldwide. TBI triggers the release of inflammatory mediators (cytokines) that aggravate cerebral damage, thereby affecting clinical prognosis. The renin angiotensin system (RAS) plays a critical role in TBI pathophysiology. RAS is widely expressed in many organs including the brain. Modulation of the RAS in the brain via angiotensin type 1 (AT₁) and type 2 (AT₂) receptor signaling affects many pathophysiological processes, including TBI. AT₁R is highly expressed in neurons and astrocytes. The upregulation of AT₁R mediates the effects of angiotensin II (ANG II) including release of proinflammatory cytokines, cell death, oxidative stress, and vasoconstriction. The AT₂R, mainly expressed in the fetal brain during development, is also related to cognitive function. Activation of this receptor pathway decreases neuroinflammation and oxidative stress and improves overall cell survival. Numerous studies have illustrated the therapeutic potential of inhibiting AT₁R and activating AT₂R for treatment of TBI with variable outcomes. In this review, we summarize studies that describe the role of brain RAS signaling, through AT₁R and AT₂R in TBI, and its modulation with pharmacological approaches.

Repurposing Antihypertensive Drugs for the Management of Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disorder that has affected millions of people worldwide. However, currently, there is no treatment to cure the disease. The AD drugs available in the market only manage the disease symptomatically and the effects are usually short-term. Thus, there is a need to look at alternatives AD therapies. This literature review aims to shed some light on the potential of repurposing antihypertensives to treat AD. Mid-life hypertension has not only been recognised as a risk factor for AD, but its relation with AD has also been well established. Hence, antihypertensives were postulated to be beneficial in managing AD. Four classes of antihypertensives, as well as their potential limitations and prospects in being utilised as AD therapeutics, were discussed in this review.

Dementia with Lewy bodies: emerging drug targets and therapeutics

Introduction: Dementia with Lewy bodies (DLB) is characterized by the toxic accumulation of α-synuclein protein inside neural cells; this results in neurodegeneration which is clinically accompanied by behavioral and psychological changes. DLB shares features with Parkinson's disease (PD) and Parkinson's disease dementia (PDD), but also overlaps neurochemically and pathologically with Alzheimer's disease. Symptomatic treatments for LBD differ in their effectiveness while disease-modifying and curative approaches are much needed.Areas covered: We explore emerging therapeutics for DLB through the lens of repurposing approved drugs and survey their potential for disease modifying actions in DLB. Given the complexity of DLB with multiple pathologies, potential therapeutic targets that could affect Lewy body pathology, or metabolism or neurotransmitters or immunomodulation were surveyed. We queried PubMed and ClinicalTrials.gov searches 2017-2020.Expert opinion: DLB is not simply aredux ofAD or PD; hence, treatments should not be exclusively duplicative ofAD or PD directed treatments. This opens amyriad of possibilities for therapeutic approaches that are disease specific or repurposed.

Olmesartan Prevents Oligomerized Amyloid β (Aβ)-Induced Cellular Senescence in Neuronal Cells

Alzheimer's disease (AD) is a neurodegenerative disease with high morbidity. The deposition of oligomerized amyloid β (Aβ) is the pathological feature of AD. The Aβ-caused neuronal oxidative stress and cellular senescence play an important role in the development and progression of AD. Olmesartan is a novel angiotensin receptor blocker with promising antihypertensive properties and has recently been reported to exert anti-inflammatory and antioxidative stress effects. Blood pressure control using Angiotensin receptor blockers has shown multiple benefits in Alzheimer's disease models. In the present study, the effect of Olmesartan on oligomerized amyloid β (Aβ)-induced cellular senescence was investigated in cultured M17 neuronal cells. Our results show that Olmesartan treatment significantly ameliorates oligomerized Aβ-elevated ROS and MDA levels, as well as the induced senescent cells number. At the molecular level, Olmesartan inhibits the elevated expression of senescence biomarkers (p16 and p21). Furthermore, Olmesartan potently reversed the increased K382 acetylation of p53 and the downregulation of SIRT1. Moreover, we show that the effect of Olmesartan against cell senescence and deacetylation of p53 was abolished by inhibition of SIRT1, either by using nicotinamide or by transfection with SIRT1 siRNA. In conclusion, Olmesartan prevents oligomerized Aβ-induced cellular senescence in neuronal cells by downregulating p16 and p21 through a SIRT1 dependent deacetylation of p53; our finding indicates that Olmesartan has a protective effect in Aβ-induced neurotoxicity.

Legumain Knockout Protects Against Aβ1-42-Induced AD-like Cognitive Deficits and Synaptic Plasticity Dysfunction Via Inhibiting Neuroinflammation Without Cleaving APP

Neuroinflammation is the important pathological feature of Alzheimer's disease (AD). Legumain, a lysosomal cysteine protease, plays an important role in neuroinflammation during ischemic stroke and depressive disorder. Legumain is involved in AD process through cleaving APP; however, it is unclear if legumain can possibly modulate neuroinflammation without cleaving APP in AD. Thus, we established a mouse model of AD by single intracerebroventricular injections of Aβ1-42 in legumain knockout (KO) mice. The behavioral tests showed that legumain-KO effectively ameliorated cognitive impairment induced by Aβ1-42. Moreover, legumain deprivation significantly improves the synaptic plasticity damages in Aβ1-42-treated mice. Moreover, legumain-KO considerably inhibited the activation of microglia and reduced the expression of inflammatory cytokines in the hippocampus of Aβ1-42-treated mice. Interestingly, we found that legumain-KO inhibited TLR4/MyD88/NF-κB pathway, which was activated by Aβ1-42 in the hippocampus. In conclusion, our results suggested that legumain-KO reduced the level of neuroinflammation that was associated with inhibiting TLR4/MyD88/NF-κB pathways, thereby improving the hippocampal synaptic plasticity and reducing the cognitive impairments in Aβ1-42-treated mice. Legumain knockout blocked microglia activation by inhibiting TLR4/MyD88/NF-κB signaling pathways, and further reduced inflammatory cytokine expression. As a result, legumain knockout alleviated synaptic damage and cognitive impairment induced by Aβ1--42.

Central nervous system diseases related to pathological microglial phagocytosis

Microglia are important phagocytes of the central nervous system (CNS). They play an important role in protecting the CNS by clearing necrotic tissue and apoptotic cells in many CNS diseases. However, recent studies have found that microglia can phagocytose parts of neurons excessively, such as the neuronal cell body, synapse, or myelin sheaths, before or after the onset of CNS diseases, leading to aggravated injury and impaired tissue repair. Meanwhile, reduced phagocytosis of synapses and myelin results in abnormal circuit connections and inhibition of remyelination, respectively. Previous studies focused primarily on the positive effects of microglia phagocytosis, whereas only a few studies have focused on the negative effects. In this review, we use the term "pathological microglial phagocytosis" to refer to excessive or reduced phagocytosis by microglia that leads to structural or functional abnormalities in target cells and brain tissue. The classification of pathological microglial phagocytosis, the composition, and activation of related signaling pathways, as well as the process of pathological phagocytosis in various kinds of CNS diseases, are described in this review. We hypothesize that pathological microglial phagocytosis leads to aggravation of tissue damage and negative functional outcome. For example, excessive microglial phagocytosis of synapses can be observed in Alzheimer's disease and schizophrenia, leading to significant synapse loss and memory impairment. In Parkinson's disease, ischemic stroke, and traumatic brain injury, excessive microglial phagocytosis of neuronal cell bodies causes impaired gray matter recovery and sensory dysfunction. We therefore believe that more studies should focus on the mechanism of pathological microglial phagocytosis and activation to uncover potential targets of therapeutic intervention.

Angiotensin (1-7) Expressing Probiotic as a Potential Treatment for Dementia

Increasing life expectancies are unfortunately accompanied by increased prevalence of Alzheimer's disease (AD). Regrettably, there are no current therapeutic options capable of preventing or treating AD. We review here data indicating that AD is accompanied by gut dysbiosis and impaired renin angiotensin system (RAS) function. Therefore, we propose the potential utility of an intervention targeting both the gut microbiome and RAS as both are heavily involved in proper CNS function. One potential approach which our group is currently exploring is the use of genetically-modified probiotics (GMPs) to deliver therapeutic compounds. In this review, we specifically highlight the potential utility of utilizing a GMP to deliver Angiotensin (1-7), a beneficial component of the renin-angiotensin system with relevant functions in circulation as well as locally in the gut and brain.

Losartan Improves Memory, Neurogenesis and Cell Motility in Transgenic Alzheimer's Mice

Angiotensin receptor blockers (ARBs) have demonstrated multiple neuroprotective benefits in Alzheimer’s disease (AD) models. However, their beneficial effects on memory deficits, cholinergic activity, neurogenesis and Amyloid beta (Aβ) clearance reveal significant interstudy variability. The delivery route can impact not only delivery but also targeting and therapeutic efficacy of ARBs. Our previous findings on the beneficial effects of intranasally delivered losartan in the APP/PS1 model of AD prompted us to explore the influence of the delivery route by employing here the systemic administration of losartan. Consistent with our previous results with intranasal losartan, repeated intraperitoneal administration (10 mg/kg) resulted in a remarkable decrease in Aβ plaques and soluble Aβ42, as well as inflammatory cytokines (IL-2, IL-6 and TNFα). The Aβ reduction can be ascribed to its facilitated degradation by neprilysin and diminished generation by BACE1. Losartan increased neurogenesis in vivo and in vitro and improved migratory properties of astrocytes isolated from adult transgenic AD mice. In summary, this data together with our previous results suggest therapeutic features of losartan which are independent of delivery route. The improvement of cell motility of Aβ-affected astrocytes by losartan deserves further in vivo investigation, which may lead to new strategies for AD treatment.

Systemic Candesartan Treatment Modulates Behavior, Synaptic Protein Levels, and Neuroinflammation in Female Mice That Express Human APOE4

Evidence suggests that angiotensin receptor blockers (ARBs) could be beneficial for Alzheimer’s disease (AD) patients independent of any effects on hypertension. However, studies in rodent models directly testing the activity of ARB treatment on behavior and AD-relevent pathology including neuroinflammation, Aβ levels, and cerebrovascular function, have produced mixed results. APOE4 is a major genetic risk factor for AD and has been linked to many of the same functions as those purported to be modulated by ARB treatment. Therefore, evaluating the effects of ARB treatment on behavior and AD-relevant pathology in mice that express human APOE4 could provide important information on whether to further develop ARBs for AD therapy. In this study, we treated female and male mice that express the human APOE4 gene in the absence (E4FAD−) or presence (E4FAD+) of high Aβ levels with the ARB prodrug candesartan cilexetil for a duration of 4 months. Compared to vehicle, candesartan treatment resulted in greater memory-relevant behavior and higher hippocampal presynaptic protein levels in female, but not male, E4FAD− and E4FAD+ mice. The beneficial effects of candesartan in female E4FAD− and E4FAD+ mice occurred in tandem with lower GFAP and Iba1 levels in the hippocampus, whereas there were no effects on markers of cerebrovascular function and Aβ levels. Collectively, these data imply that the effects of ARBs on AD-relevant pathology may be modulated in part by the interaction between APOE genotype and biological sex. Thus, the further development of ARBs could provide therapeutic options for targeting neuroinflammation in female APOE4 carriers.

Renin-Angiotensin System and Alzheimer's Disease Pathophysiology: From the Potential Interactions to Therapeutic Perspectives

New roles of the Renin-Angiotensin System (RAS), apart from fluid homeostasis and Blood Pressure (BP) regulation, are being progressively unveiled, since the discoveries of RAS alternative axes and local RAS in different tissues, including the brain. Brain RAS is reported to interact with pathophysiological mechanisms of many neurological and psychiatric diseases, including Alzheimer's Disease (AD). Even though AD is the most common cause of dementia worldwide, its pathophysiology is far from elucidated. Currently, no treatment can halt the disease course. Successive failures of amyloid-targeting drugs have challenged the amyloid hypothesis and increased the interest in the inflammatory and vascular aspects of AD. RAS compounds, both centrally and peripherally, potentially interact with neuroinflammation and cerebrovascular regulation. This narrative review discusses the AD pathophysiology and its possible interaction with RAS, looking forward to potential therapeutic approaches. RAS molecules affect BP, cerebral blood flow, neuroinflammation, and oxidative stress. Angiotensin (Ang) II, via angiotensin type 1 receptors may promote brain tissue damage, while Ang-(1-7) seems to elicit neuroprotection. Several studies dosed RAS molecules in AD patients' biological material, with heterogeneous results. The link between AD and clinical conditions related to classical RAS axis overactivation (hypertension, heart failure, and chronic kidney disease) supports the hypothesized role of this system in AD. Additionally, RAStargeting drugs as Angiotensin Converting Enzyme inhibitors (ACEis) and Angiotensin Receptor Blockers (ARBs) seem to exert beneficial effects on AD. Results of randomized controlled trials testing ACEi or ARBs in AD are awaited to elucidate whether AD-RAS interaction has implications on AD therapeutics.

Losartan Treatment Could Improve the Outcome of TBI Mice

Traumatic brain injury frequently leads to serious mortality and physical disability, yet effective treatments remains insufficient. TBI always leads to a series of secondary brain injuries including neuronal apoptosis, continuous inflammation, endoplasmic reticulum stress, and disruption of the blood-brain barrier. Sartans that block angiotensin II type 1 receptors are strongly neuroprotective, neurorestorative and anti-inflammatory. However, whether losartan, a FDA-approved and widely used drug for regulating blood pressure, is beneficial for improving the prognosis of TBI need more evidence. Through a controlled cortical impact injury mice model, we confirmed that losartan treatment could ameliorate CCI-induced secondary brain injury. We found that losartan treatment decreased brain lesion volume, neuronal apoptosis and ER stress protein ATF4 and eIF2α. Moreover, our results showed that losartan also improved neurological and motor function. It is worth pointing out that losartan increased the expression of tight junction proteins ZO-1 and alleviated brain edema and blood brain barrier leakage. Additionally, losartan inhibited pro-inflammatory factor TNF-α and improve anti-inflammatory factor IL-10. Taken together, our data demonstrated that losartan could improve the prognosis of TBI and may be a promising therapeutic method for mitigating TBI.

Repositioning medication for cardiovascular and cerebrovascular disease to delay the onset and prevent progression of Alzheimer's disease

Alzheimer's disease (AD) is a complex, progressive, neurodegenerative disorder. As with other common chronic diseases, multiple risk factors contribute to the onset and progression of AD. Many researchers have evaluated the epidemiologic and pathophysiological association between AD, cardiovascular diseases (CVDs), and cerebrovascular diseases (CBVDs), including commonly reported risk factors such as diabetes, hypertension, and dyslipidemia. Relevant therapies of CVDs/CBVDs for the attenuation of AD have also been empirically investigated. Considering the challenges of new drug development, in terms of cost and time, multifactorial approaches such as therapeutic repositioning of CVD/CBVD medication should be explored to delay the onset and progression of AD. Thus, in this review, we discuss our current understanding of the association between cardiovascular risk factors and AD, as revealed by clinical and non-clinical studies, as well as the therapeutic implications of CVD/CBVD medication that may attenuate AD. Furthermore, we discuss future directions by evaluating ongoing trials in the field.

Pharmacological approaches to mitigate neuroinflammation in Alzheimer's disease

Alzheimer's disease (AD) is one of the most prevalent neurodegenerative diseases characterized by the formation of extracellular amyloid beta (Aβ) plaques and intracellular neurofibrillary tangles (NFTs). Growing evidence suggested that there is an association between neuronal dysfunction and neuroinflammation (NI) in AD, coordinated by the chronic activation of astrocytes and microglial cells along with the subsequent excessive generation of the proinflammatory molecule. Therefore, a better understanding of the relationship between the nervous and immune systems is important in order to delay or avert the neurodegenerative events of AD. The inflammatory/immune pathways and the mechanisms to control these pathways may provide a novel arena to develop new drugs in order to target NI in AD. In this review, we represent the influence of cellular mediators which are involved in the NI process, with regards to the progression of AD. We also discuss the processes and the current status of multiple anti-inflammatory agents which are used in AD and have gone through or going through clinical trials. Moreover, new prospects for targeting NI in the development of AD drugs have also been highlighted.

Gut microbiota and neuroinflammation in pathogenesis of hypertension: A potential role for hydrogen sulfide

Inflammation and gut dysbiosis are hallmarks of hypertension (HTN). Hydrogen sulfide (H2S) is an important freely diffusing molecule that modulates the function of neural, cardiovascular and immune systems, and circulating levels of H2S are reduced in animals and humans with HTN. While most research to date has focused on H₂S produced endogenously by the host, H2S is also produced by the gut bacteria and may affect the host homeostasis. Here, we review an association between neuroinflammation and gut dysbiosis in HTN, with special emphasis on a potential role of H2S in this interplay.

Solid State Stability and Kinetics of Degradation for Candesartan-Pure Compound and Pharmaceutical Formulation

The aim of this work was to assess the impact of an excipient in a pharmaceutical formulation containing candesartan cilexetil over the decomposition of the active pharmaceutical ingredient and to comparatively investigate the kinetics of degradation during thermolysis in an oxidative atmosphere under controlled thermal stress. To achieve this, the samples were chosen as follows: pure candesartan cilexetil and a commercial tablet of 32 mg strength. As a first investigational tool, Universal attenuated total reflection Fourier transform infrared (UATR-FTIR) spectroscopy was chosen in order to confirm the purity and identity of the samples, as well as to check if any interactions took place in the tablet between candesartan cilexetil and excipients under ambient conditions. Later on, samples were investigated by thermal analysis, and the elucidation of the decomposition mechanism was achieved solely after performing an in-depth kinetic study, namely the use of the modified non-parametric kinetics (NPK) method, since other kinetic methods (American Society for Testing and Materials—ASTM E698, Friedman and Flynn–Wall–Ozawa) led to inadvertencies. The NPK method suggested that candesartan cilexetil and the tablet were degraded by the contribution of two steps, the main being represented by chemical degradation and the secondary being a physical transformation. The excipients chosen in the formulation seemed to have a stabilizing effect on the decomposition of the candesartan cilexetil that was incorporated into the tablet, relative to pure active pharmaceutical ingredient (API), since the apparent activation energy for the decomposition of the tablet was 192.5 kJ/mol, in comparison to 154.5 kJ/mol for the pure API.

Nicotinamide riboside rescues angiotensin II-induced cerebral small vessel disease in mice

Aims

Hypertension is a leading cause of cerebral small vessel disease (CSVD). Currently, treatments for CSVD are limited. Nicotinamide riboside (NR) can protect against vascular injury and cognitive impairment in neurodegenerative diseases. In this study, the protective effects of NR against angiotensin ‐ (Ang ‐)–induced CSVD were evaluated.

Methods

To explore the effects of NR in CSVD, C57BL/6 mice were infused with Ang ‐, and NR was added to the food of the mice for 28 days. Then, short‐term memory, blood‐brain barrier (BBB) integrity, and endothelial function were detected. Arteriole injury and glial activation were also evaluated.

Results

Our data showed that mice infused with Ang ‐ exhibited decreased short‐term memory function and BBB leakage due to decreased claudin‐5 expression and increased caveolae‐mediated endocytosis after 28 days. Furthermore, Ang ‐ decreased the expression of α‐smooth muscle actin (α‐SMA) and increased the expression of proliferating cell nuclear antigen (PCNA) in arterioles and decreased the expression of neurofilament 200 (NF200) and myelin basic protein (MBP) in the white matter. These CSVD‐related damages induced by Ang ‐ were inhibited by NR administration. Moreover, NR administration significantly reduced glial activation around the vessels.

Conclusion

Our results indicated that NR administration alleviated Ang ‐–induced CSVD by protecting BBB integrity, vascular remodeling, neuroinflammation, and white matter injury (WMI)–associated cognitive impairment.

Current Status of Drug Targets and Emerging Therapeutic Strategies in the Management of Alzheimer's Disease

Alzheimer's disease (AD) is a chronic neurodegenerative disease affecting the elderly. AD is associated with a progressive decline in memory and cognitive abilities, drastic changes in behavioural patterns and other psychiatric manifestations. It leads to a significant decline in the quality of life at personal, household as well as national level. Although AD was described about hundred years back and multiple theories have been proposed, its exact pathophysiology is unknown. There is no cure for AD and the life expectancy of AD patients remains low at 3-9 years. An accurate understanding of the molecular mechanism(s) involved in the pathogenesis of AD is imperative to devise a successful treatment strategy. This review explains and summarises the current understanding of different therapeutic strategies based on various molecular pathways known to date. Different strategies based on anti-amyloid pathology, glutamatergic pathway, anti-tau, neuroprotection through neurotrophic factors and cholinergic neurotransmission have been discussed. Further, the use of anti-inflammatory drugs, nutraceuticals, and dietary interventions has also been explained in the management of AD. It further describes different pharmacological and dietary interventions being used in treating and/or managing AD. Additionally, this article provides a thorough review of the literature for improving the therapeutic paradigm of AD.

Hypertension and Its Impact on Stroke Recovery: From a Vascular to a Parenchymal Overview

Hypertension is the first modifiable vascular risk factor accounting for 10.4 million deaths worldwide; it is strongly and independently associated with the risk of stroke and is related to worse prognosis. In addition, hypertension seems to be a key player in the implementation of vascular cognitive impairment. Long-term hypertension, complicated or not by the occurrence of ischemic stroke, is often reviewed on its vascular side, and parenchymal consequences are put aside. Here, we sought to review the impact of isolated hypertension or hypertension associated to stroke on brain atrophy, neuron connectivity and neurogenesis, and phenotype modification of microglia and astrocytes. Finally, we discuss the impact of antihypertensive therapies on cell responses to hypertension and functional recovery. This attractive topic remains a focus of continued investigation and stresses the relevance of including this vascular risk factor in preclinical investigations of stroke outcome.

Alzheimer's dementia: pathogenesis and impact of cardiovascular risk factors on cognitive decline

Alzheimer's disease (AD) is the most common form of dementia manifesting as alterations in cognitive abilities, behavior, and deterioration in memory which is progressive, leading to gradual worsening of symptoms. Major pathological features of AD are accumulations of neuronal amyloid plaques and neurofibrillary tangles, with early lesions appearing primarily in the hippocampus, the area of the brain involved in memory and learning. Cardiovascular-related risk factors are believed to play a crucial role in disease development and the acceleration of cognitive deterioration by worsening cerebral perfusion, promoting disturbances in amyloid clearance. Current evidence supports hypertension, hypotension, heart failure, stroke and coronary artery diseases as potential factors playing a role in cognitive decline in patients with Alzheimer's dementia. Although dementia due to cardiovascular deficits is more strongly linked to the development of vascular dementia, a stepwise decline in cognition, recent researches have also discovered its deleterious influence on AD development.

The Anti-inflammatory Compound Candesartan Cilexetil Improves Neurological Outcomes in a Mouse Model of Neonatal Hypoxia

Recent studies suggest that mild hypoxia-induced neonatal seizures can trigger an acute neuroinflammatory response leading to long-lasting changes in brain excitability along with associated cognitive and behavioral deficits. The cellular elements and signaling pathways underlying neuroinflammation in this setting remain incompletely understood but could yield novel therapeutic targets. Here we show that brief global hypoxia-induced neonatal seizures in mice result in transient cytokine production, a selective expansion of microglia and long-lasting changes to the neuronal structure of pyramidal neurons in the hippocampus. Treatment of neonatal mice after hypoxia-seizures with the novel anti-inflammatory compound candesartan cilexetil suppressed acute seizure-damage and mitigated later-life aggravated seizure responses and hippocampus-dependent learning deficits. Together, these findings improve our understanding of the effects of neonatal seizures and identify potentially novel treatments to protect against short and long-lasting harmful effects.

An Overview of Experimental and Clinical Spinal Cord Findings in Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disorder that occurs mainly in the elderly and presenile life stages. It is estimated that by the year 2050, 135 million people will be affected by AD worldwide, representing a huge burden to society. The pathological hallmarks of AD mainly include intracellular neurofibrillary tangles (NFTs) caused by hyperphosphorylation of tau protein, formation of extracellular amyloid plaques, and massive neural cell death in the affected nervous system. The pathogenesis of AD is very complicated, and recent scientific research on AD is mainly concentrated on the cortex and hippocampus. Although the spinal cord is a pivotal part of the central nervous system, there are a limited number of studies focusing on the spinal cord. As an extension of the brain, the spinal cord functions as the bridge between the brain and various parts of the body. However, pathological changes in the spinal cord in AD have not been comprehensively and systematically studied at present. We here review the existing progress on the pathological features of AD in the spinal cord.

Neuroprotective Approach of Anti-Cancer Microtubule Stabilizers Against Tauopathy Associated Dementia: Current Status of Clinical and Preclinical Findings

Neuronal microtubule (MT) tau protein provides cytoskeleton to neuronal cells and plays a vital role including maintenance of cell shape, intracellular transport, and cell division. Tau hyperphosphorylation mediates MT destabilization resulting in axonopathy and neurotransmitter deficit, and ultimately causing Alzheimer’s disease (AD), a dementing disorder affecting vast geriatric populations worldwide, characterized by the existence of extracellular amyloid plaques and intracellular neurofibrillary tangles in a hyperphosphorylated state. Pre-clinically, streptozotocin stereotaxically mimics the behavioral and biochemical alterations similar to AD associated with tau pathology resulting in MT assembly defects, which proceed neuropathological cascades. Accessible interventions like cholinesterase inhibitors and NMDA antagonist clinically provides only symptomatic relief. Involvement of microtubule stabilizers (MTS) prevents tauopathy particularly by targeting MT oriented cytoskeleton and promotes polymerization of tubulin protein. Multiple in vitro and in vivo research studies have shown that MTS can hold substantial potential for the treatment of AD-related tauopathy dementias through restoration of tau function and axonal transport. Moreover, anti-cancer taxane derivatives and epothiolones may have potential to ameliorate MT destabilization and prevent the neuronal structural and functional alterations associated with tauopathies. Therefore, this current review strictly focuses on exploration of various clinical and pre-clinical features available for AD to understand the neuropathological mechanisms as well as introduce pharmacological interventions associated with MT stabilization. MTS from diverse natural sources continue to be of value in the treatment of cancer, suggesting that these agents have potential to be of interest in the treatment of AD-related tauopathy dementia in the future.

Intranasal Losartan Decreases Perivascular Beta Amyloid, Inflammation, and the Decline of Neurogenesis in Hypertensive Rats

The contribution of the local angiotensin receptor system to neuroinflammation, impaired neurogenesis, and amyloid beta (Aβ) accumulation in Alzheimer's disease (AD) and in hypertension is consistent with the remarkable neuroprotection provided by angiotensin receptor blockers (ARBs) independent of their blood pressure-lowering effect. Considering the causal relationship between hypertension and AD and that targeting cerebrovascular pathology with ARBs does not necessarily require their systemic effects, we tested intranasal losartan in the rat model of chronic hypertension (spontaneously hypertensive stroke-prone rats, SHRSP). Intranasal losartan at a subdepressor dose decreased mortality, neuroinflammation, and perivascular content of Aβ by enhancing key players in its metabolism and clearance, including insulin-degrading enzyme, neprilysin, and transthyretin. Furthermore, this treatment improved neurologic deficits and increased brain IL-10 concentration, hippocampal cell survival, neurogenesis, and choroid plexus cell proliferation in SHRSP. Losartan (1 μM) also reduced LDH release from cultured astroglial cells in response to toxic glutamate concentrations. This effect was completely blunted by IL-10 antibodies. These findings suggest that intranasal ARB treatment is a neuroprotective, neurogenesis-inducing, and Aβ-decreasing strategy for the treatment of hypertensive stroke and cerebral amyloid angiopathy acting at least partly through the IL-10 pathway.

Targeting Neuroinflammation as a Therapeutic Strategy for Alzheimer's Disease: Mechanisms, Drug Candidates, and New Opportunities

Alzheimer's disease is a progressive neurodegenerative disease, and its incidence is expected to increase owing to the aging population worldwide. Current therapies merely provide symptomatic relief. Therefore, interventions for AD that delay the disease onset or progression are urgently required. Recent genomics and functional studies suggest that immune/inflammatory pathways are involved in the pathogenesis of AD. Although many anti-inflammatory drug candidates have undergone clinical trials, most have failed. This might be because of our limited understanding of the pathological mechanisms of neuroinflammation in AD. However, recent advances in the understanding of immune/inflammatory pathways in AD and their regulatory mechanisms could open up new avenues for drug development targeting neuroinflammation. In this Review, we discuss the mechanisms and status of different anti-inflammatory drug candidates for AD that have undergone or are undergoing clinical trials and explore new opportunities for targeting neuroinflammation in AD drug development.

Discovery of 4'-OH-flurbiprofen Mannich base derivatives as potential Alzheimer's disease treatment with multiple inhibitory activities

A series of 4'-OH flurbiprofen Mannich base derivatives were designed, synthesized and evaluated as potential multifunctional agents for the treatment of Alzheimer's disease. The biological screening results indicated that most of these derivatives exhibited good multifunctional activities. Among them, compound 8n demonstrated the best inhibitory effects on self-induced Aβ_1-42 aggregation (65.03% at 25.0 μM). Moreover, this representative compound also exhibited good antioxidant activity, biometal chelating ability and anti-neuroinflammatory activity in vitro. Furthermore, compound 8n displayed appropriate blood-brain barrier permeability. These multifunctional properties highlight compound 8n as promising candidate for further development of multi-functional drugs against AD.