Telmisartan ameliorates Aβ oligomer-induced inflammation via PPARγ/PTEN pathway in BV2 microglial cells

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.

Inflammatory signaling pathways in the treatment of Alzheimer's disease with inhibitors, natural products and metabolites (Review)

The intricate nature of Alzheimer's disease (AD) pathogenesis poses a persistent obstacle to drug development. In recent times, neuroinflammation has emerged as a crucial pathogenic mechanism of AD, and the targeting of inflammation has become a viable approach for the prevention and management of AD. The present study conducted a comprehensive review of the literature between October 2012 and October 2022, identifying a total of 96 references, encompassing 91 distinct pharmaceuticals that have been investigated for their potential impact on AD by inhibiting neuroinflammation. Research has shown that pharmaceuticals have the potential to ameliorate AD by reducing neuroinflammation mainly through regulating inflammatory signaling pathways such as NF‑κB, MAPK, NLRP3, PPARs, STAT3, CREB, PI3K/Akt, Nrf2 and their respective signaling pathways. Among them, tanshinone IIA has been extensively studied for its anti‑inflammatory effects, which have shown significant pharmacological properties and can be applied clinically. Thus, it may hold promise as an effective drug for the treatment of AD. The present review elucidated the inflammatory signaling pathways of pharmaceuticals that have been investigated for their therapeutic efficacy in AD and elucidates their underlying mechanisms. This underscores the auspicious potential of pharmaceuticals in ameliorating AD by impeding neuroinflammation.

Telmisartan inhibits microglia-induced neurotoxic A1 astrocyte conversion via PPARγ-mediated NF-κB/p65 degradation

Astrocytes are crucially involved in neuroinflammation. Activated astrocytes exhibit at least two phenotypes, A1 (neurotoxic) and A2 (neuroprotective). The A1 phenotype is the major reactive astrocyte phenotype involved in aging and neurodegenerative diseases. Telmisartan, which is an antihypertensive agent, is a promising neuroprotective agent. This study aimed to investigate the effects of telmisartan on the phenotype of reactive astrocytes. Astrocytes were activated by culturing with the conditioned medium derived from lipopolysaccharide-stimulated microglia. This conditioned medium induced early, transient A2 astrocyte conversion (within 24 h) and late, sustained A1 conversion (beginning at 24 h and lasting up to 7 days), with a concomitant increase in the production of pro-inflammatory cytokines (interleukin [IL]-1β, tumor necrosis factor [TNF]α, and IL-6) and phosphorylation of nuclear factor-κB (NF-κB)/p65. Telmisartan treatment promoted and inhibited A2 and A1 conversion, respectively. Telmisartan reduced total and phosphorylated p65 protein levels. Losartan, a specific angiotensin II type-1 receptor (AT1R) blocker, did not influence the reactive state of astrocytes. Additionally, AT1R activation by angiotensin II did not induce the expression of pro-inflammatory cytokines and A1/A2 markers, indicating that the AT1R signaling pathway is not involved in the astrocyte-mediated inflammatory response. A peroxisome proliferator-activated receptor γ (PPARγ) antagonist reversed the effects of telmisartan. Moreover, telmisartan-induced p65 downregulation was reversed by the proteasome inhibitor MG132. These results indicate that telmisartan suppresses activated microglia-induced neurotoxic A1 astrocyte conversion through p65 degradation. Our findings contribute towards the elucidation of the anti-inflammatory activity of telmisartan in brain disorders.

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.

Alzheimer's disease and neuroinflammation: will new drugs in clinical trials pave the way to a multi-target therapy?

Despite extensive research, no disease-modifying therapeutic option, able to prevent, cure or halt the progression of Alzheimer's disease [AD], is currently available. AD, a devastating neurodegenerative pathology leading to dementia and death, is characterized by two pathological hallmarks, the extracellular deposits of amyloid beta (Aβ) and the intraneuronal deposits of neurofibrillary tangles (NFTs) consisting of altered hyperphosphorylated tau protein. Both have been widely studied and pharmacologically targeted for many years, without significant therapeutic results. In 2022, positive data on two monoclonal antibodies targeting Aβ, donanemab and lecanemab, followed by the 2023 FDA accelerated approval of lecanemab and the publication of the final results of the phase III Clarity AD study, have strengthened the hypothesis of a causal role of Aβ in the pathogenesis of AD. However, the magnitude of the clinical effect elicited by the two drugs is limited, suggesting that additional pathological mechanisms may contribute to the disease. Cumulative studies have shown inflammation as one of the main contributors to the pathogenesis of AD, leading to the recognition of a specific role of neuroinflammation synergic with the Aβ and NFTs cascades. The present review provides an overview of the investigational drugs targeting neuroinflammation that are currently in clinical trials. Moreover, their mechanisms of action, their positioning in the pathological cascade of events that occur in the brain throughout AD disease and their potential benefit/limitation in the therapeutic strategy in AD are discussed and highlighted as well. In addition, the latest patent requests for inflammation-targeting therapeutics to be developed in AD will also be discussed.

Aβ Oligomer Toxicity-Reducing Therapy for the Prevention of Alzheimer's Disease: Importance of the Nrf2 and PPARγ Pathways

Recent studies have revealed that soluble amyloid-β oligomers (AβOs) play a pathogenetic role in Alzheimer's disease (AD). Indeed, AβOs induce neurotoxic and synaptotoxic effects and are also critically involved in neuroinflammation. Oxidative stress appears to be a crucial event underlying these pathological effects of AβOs. From a therapeutic standpoint, new drugs for AD designed to remove AβOs or inhibit the formation of AβOs are currently being developed. However, it is also worth considering strategies for preventing AβO toxicity itself. In particular, small molecules with AβO toxicity-reducing activity have potential as drug candidates. Among such small molecules, those that can enhance Nrf2 and/or PPARγ activity can effectively inhibit AβO toxicity. In this review, I summarize studies on the small molecules that counteract AβO toxicity and are capable of activating Nrf2 and/or PPARγ. I also discuss how these interrelated pathways are involved in the mechanisms by which these small molecules prevent AβO-induced neurotoxicity and neuroinflammation. I propose that AβO toxicity-reducing therapy, designated ATR-T, could be a beneficial, complementary strategy for the prevention and treatment of AD.

Melatonin ameliorates myocardial infarction in obese diabetic individuals: The possible involvement of macrophage apoptotic factors

In recent days, the hike in obesity-mediated epidemics across the globe and the prevalence of obesity-induced cardiovascular disease has become one of the chief grounds for morbidity and mortality. This epidemic-driven detrimental events in the cardiac tissues start with the altered distribution and metabolism pattern of high-density lipoprotein and low-density lipoprotein (LDL) leading to cholesterol (oxidized LDL) deposition on the arterial wall and atherosclerotic plaque generation, followed by vascular spasms and infarction. Subsequently, obesity-triggered metabolic malfunctions induce free radical generation which may further trigger pro-inflammatory signaling and nuclear factor kappa-light-chain-enhancer of activated B cells transcriptional factor, thus inducing interferon-gamma, tumor necrosis factor-alpha, and inducible nitric oxide synthase. This terrifying cardiomyopathy can be further aggravated in type 2 diabetes mellitus, thereby making obese diabetic patients prone toward the development of myocardial infarction (MI) or stroke in comparison to their nondiabetic counterparts. The accelerated oxidative stress and pro-inflammatory response induced cardiomyocyte hypertrophy, followed by apoptosis in obese diabetic individuals, causing progression of athero-thrombotic vascular disease. Being an efficient antioxidative and anti-inflammatory indolamine, melatonin effectively inhibits lipid peroxidation, pro-inflammatory reactions, thereby resolving free radical-induced myocardial damages along with maintaining antioxidant reservoir to preserve cardiovascular integrity. Prolonged melatonin treatment maintains balanced body weight and serum total cholesterol concentration by inhibiting cholesterol synthesis and promoting cholesterol catabolism. Additionally, melatonin promotes macrophage polarization toward the anti-inflammatory state, providing a proper shield during the recovery period. Therefore, the protective role of melatonin in maintaining the lipid metabolism homeostasis and blocking the atherosclerotic plaque rupture could be targeted as the possible therapeutic strategy for the management of obesity-induced acute MI. This review aimed at orchestrating the efficacy of melatonin in ameliorating irrevocable oxidative cardiovascular damage induced by the obesity-diabetes correlation.

Phosphatase and tensin homologue determine inflammatory status by differentially regulating the expression of Akt1 and Akt2 in macrophage alternative polarization of periodontitis

AIM

Macrophages are closely involved in periodontitis. However, the molecular mechanism by which macrophages influence periodontitis is not well understood. We investigated the effects of phosphatase and tensin homologue (PTEN) on macrophage polarization, the underlying mechanism and the regulatory roles in periodontium regeneration.

MATERIALS AND METHODS

PTEN expression in periodontitis macrophages was detected ex vivo. The effects of PTEN on macrophage polarization and the underlying mechanisms were investigated in vitro. We also analysed the ability of PTEN inhibitors to repair periodontitis in vivo in a ligature-induced mouse model of periodontitis.

RESULTS

Macrophage PTEN expression in periodontitis patients was significantly higher than that of controls. PTEN inhibition in macrophages induced alternative macrophage polarization, whereas PTEN overexpression facilitated classical polarization. PTEN inhibition facilitated activation of Akt1 while inhibiting expression of Akt2. Furthermore, Akt2 overexpression could rescue the effects of PTEN inhibition on NF-κB. Treatment with a PTEN inhibitor significantly attenuated the local inflammatory status and prevented alveolar bone resorption in the mouse model.

CONCLUSIONS

Our findings suggest that PTEN inhibition could induce alternative macrophage polarization by differentially regulating Akt1 and Akt2. This also changed a pro-inflammatory microenvironment to an anti-inflammatory environment by subsequently regulating the expression of NF-κB, thereby attenuating inflammatory alveolar bone resorption induced by ligature.

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.

Knockdown of SEMA7A alleviates MPP+ -induced apoptosis and inflammation in BV2 microglia via PPAR-γ activation and MAPK inactivation

INTRODUCTION

The inflammation mediated by microglial cells plays an important role in the process of neurodegenerative diseases. Recent evidence indicates that semaphorin 7A (SEMA7A) is implicated in various neurodegenerative diseases, but whether it plays a role in Parkinson's disease (PD) remains unclear.

METHODS

In this study, 1.0 mmol/L 1-methyl-4-phenylpyridinium (MPP+ )-stimulated mouse microglia (BV2) cells were used as an in vitro model of PD. The expression of SEMA7A was detected by quantitative polymerase chain reaction. Cell Counting Kit-8 and apoptosis kits were used to analyze the viability and apoptosis of BV-2 cells. The content of IL-6, IL-β, and tumor necrosis factor-α was determined by ELISA (enzyme-linked immunosorbent assay) kit. Western blot was used to detect the protein expression level of the inducible NO synthase and cyclooxygenase-2.

RESULTS

Our findings indicated that SEMA7A expression in BV2 cells was upregulated after MPP+ stimulation. Knockdown of SEMA7A promoted cell viability while it inhibited apoptosis and the expression of proinflammatory enzymes and proinflammatory cytokines. Silencing SEMA7A-induced peroxisome proliferator-activated receptor-gamma (PPAR-γ) activation and mitogen-activated protein kinase (MAPK) signaling pathway inactivation. Furthermore, a PPAR-γ inhibitor and an MAPK activator promoted the effect of MPP+ on cell viability, apoptosis, and inflammation of BV2 cells; what is more, the PPAR-γ inhibitor and MAPK activator blocked the inhibitory effect of SEMA7A downregulation on MPP+ -induced injury.

CONCLUSION

In general, knockdown of SEMA7A inhibits MPP+ -induced BV2 cell apoptosis and inflammation via PPAR-γ activation and MAPK inactivation, which may provide a new therapy target for PD.

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.

The rationale for the treatment of long-Covid symptoms – A cardiologist's view

The ongoing coronavirus disease 2019 pandemic left us with thousands of patients suffering from neurological, cardiovascular, and psychiatric disorders named post-acute sequelae of COVID-19 or just long-Covid. In parallel, the vaccination campaigns against SARS-CoV-2 spike protein saved millions of lives worldwide but long-Covid symptoms also appeared rarely following vaccination with a strong overlap to the “canonical” long-Covid symptoms. A therapeutic strategy targeting both, post-VAC and post-SARS-CoV-2 long-Covid symptoms is warranted since exposure to the S-protein either by vaccination or SARS-CoV-2 infection may trigger identical immuno-inflammatory cascades resulting in long-Covid symptoms.

Addressing Peroxisome Proliferator-Activated Receptor-gamma in 3-Nitropropionic Acid-Induced Striatal Neurotoxicity in Rats

Telmisartan (TEL) is an angiotensin II type 1 receptor blocker and a partial activator of peroxisome proliferator-activated receptor-gamma (PPARγ), which regulates inflammatory and apoptotic pathways. Increasing evidence has demonstrated the PPARγ agonistic property of TEL in several brain disorders. This study aims to explore the neuroprotective impact of TEL in 3-nitropropionic acid (3-NP)-induced neurotoxicity in rats. The PPARγ effect of TEL was affirmed by using the PPARγ agonist pioglitazone (PIO), and the antagonist GW9662. 3-NP led to a significant reduction in body weight alongside motor and cognitive functioning. The striata of the 3-NP-treated rats showed energy-deficit, microglia-mediated inflammatory reactions, apoptotic damage as well as histopathological lesions. PIO and TEL improved motor and cognitive perturbations induced by 3-NP, as confirmed by striatal histopathological examination, energy restoration, and neuronal preservation. Both drugs improved mitochondrial biogenesis evidenced by elevated mRNA expression of PPARγ, PGC-1α, and TFAM, alongside increased striatal ATP and SDH. The mitochondrial effect of TEL was beyond PPARγ activation. As well, their anti-inflammatory effect was attributed to suppression of microglial activation, and protein expression of pS536 p65 NF-κB with marked attenuation of striatal inflammatory mediator's release. Anti-inflammatory cytokine IL-10 expression was concurrently increased. TEL effectively participated in neuronal survival as it promoted phosphorylation of Akt/GSK-3β, further increased Bcl-2 expression, and inhibited cleavage of caspase-3. Interestingly, co-treatment with GW9662 partially revoked the beneficial effects of TEL. These findings recommend that TEL improves motor and cognitive performance, while reducing neuronal inflammation and apoptosis in 3-NP-induced neurotoxicity via a PPARγ-dependent mechanism.

Recent Advances in the Endogenous Brain Renin-Angiotensin System and Drugs Acting on It

The RAS (renin-angiotensin system) is the part of the endocrine system that plays a prime role in the control of essential hypertension. Since the discovery of brain RAS in the seventies, continuous efforts have been put by the scientific committee to explore it more. The brain has shown the presence of various components of brain RAS such as angiotensinogen (AGT), converting enzymes, angiotensin (Ang), and specific receptors (ATR). AGT acts as the precursor molecule for Ang peptides—I, II, III, and IV—while the enzymes such as prorenin, ACE, and aminopeptidases A and N synthesize it. AT1, AT2, AT4, and mitochondrial assembly receptor (MasR) are found to be plentiful in the brain. The brain RAS system exhibits pleiotropic properties such as neuroprotection and cognition along with regulation of blood pressure, CVS homeostasis, thirst and salt appetite, stress, depression, alcohol addiction, and pain modulation. The molecules acting through RAS predominantly ARBs and ACEI are found to be effective in various ongoing and completed clinical trials related to cognition, memory, Alzheimer's disease (AD), and pain. The review summarizes the recent advances in the brain RAS system highlighting its significance in pathophysiology and treatment of the central nervous system-related disorders.

Telmisartan Mitigates High-Glucose-Induced Injury in Renal Glomerular Endothelial Cells (rGECs) and Albuminuria in Diabetes Mice

Diabetic nephropathy (DN) is a common and severe complication of diabetes, impacting millions of people worldwide. High concentrations of serum glucose-associated injury of renal glomerular endothelial cells (rGECs) are involved in the DN pathogenesis. We found that exposure to high glucose increased the expression of angiotensin II type 1 receptor (AT1R) in human rGECs (hrGECs). To block the increased AT1R level, we used the newly developed antagonist Telmisartan. This study investigated whether Telmisartan possessed a beneficial effect against high-glucose-induced insults in hrGECs and explored the underlying mechanism. Our findings indicate that Telmisartan ameliorated high-glucose-induced mitochondrial dysfunction by increasing mitochondrial membrane potential. Also, Telmisartan attenuated oxidative stress by reducing the levels of two oxidative stress biomarkers 8-hydroxy-2 deoxyguanosine (8-OHDG) and malondialdehyde (MDA). Further, we found that Telmisartan prevented high-glucose-induced expression of NADPH oxidase 2 (NOX-2). Interestingly, exposure to high glucose resulted in the increased endothelial permeability of renal glomerular endothelial cells, which was mitigated by treatment with Telmisartan. Mechanistically, these effects are mediated by the MLCK/MLC-2/occludin signaling pathway. In the leptin-deficient db/db diabetic mouse model, we proved that Telmisartan treatment ameliorated the reduction of occludin and albuminuria. In conclusion, our findings demonstrate that Telmisartan possesses protective effects on high-glucose-induced injury to renal glomerular endothelial cells; its antagonizing of AT1R could be a potential therapeutic target in diabetic nephropathy.

The Antihypertensive Drug Telmisartan Protects Oligodendrocytes from Cholesterol Accumulation and Promotes Differentiation by a PPAR-γ-Mediated Mechanism

Our previous studies have demonstrated that specific peroxisome proliferator-activated receptor-γ (PPAR-γ) agonists play a fundamental role in oligodendrocyte progenitor (OP) differentiation, protecting them against oxidative and inflammatory damage. The antihypertensive drug Telmisartan (TLM) was shown to act as a PPAR-γ modulator. This study investigates the TLM effect on OP differentiation and validates its capability to restore damage in a pharmacological model of Niemann-Pick type C (NPC) disease through a PPAR-γ-mediated mechanism. For the first time in purified OPs, we demonstrate that TLM-induced PPAR-γ activation downregulates the type 1 angiotensin II receptor (AT1), the level of which naturally decreases during differentiation. Like other PPAR-γ agonists, we show that TLM promotes peroxisomal proliferation and promotes OP differentiation. Furthermore, TLM can offset the OP maturation arrest induced by a lysosomal cholesterol transport inhibitor (U18666A), which reproduces an NPC1-like phenotype. In the NPC1 model, TLM also reduces cholesterol accumulation within peroxisomal and lysosomal compartments and the contacts between lysosomes and peroxisomes, revealing that TLM can regulate intracellular cholesterol transport, crucial for myelin formation. Altogether, these data indicate a new potential use of TLM in hypomyelination pathologies such as NPC1, underlining the possible repositioning of the drug already used in other pathologies.

Telmisartan alleviates alcohol-induced liver injury by activation of PPAR-γ/ Nrf-2 crosstalk in mice

Excessive consumption of alcohol may induce severe liver damage, in part via oxidative stress and inflammatory responses, which implicates these processes as potential therapeutic approaches. Prior literature has shown that Telmisartan (TEL) may provide protective effects, presumably mediated by its anti-oxidant and anti-inflammatory activities. The purpose of this study was to determine TEL's hepatoprotective effects and to identify its possible curative mechanisms in alcoholic liver disease. A mouse chronic alcohol plus binge feedings model was used in the current study for induction of alcoholic liver disease (ALD). Our results showed that TEL (10 mg/kg/day) has the ability to reduce serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP). TEL also increased the activity of superoxide dismutase (SOD) and glutathione (GSH) with concomitant reduction of nitric oxide (NO) malonaldehyde (MDA) in the liver homogenate. Moreover, TEL downregulated nuclear factor kappa B (NF-κB) expression and decreased liver content of interleukin-6 (IL-6), interleukin-1β (IL-1β), and tumor necrosis factor-α (TNF-α). These anti-inflammatory and anti-oxidant activities were associated with a significant increase in the expression of nuclear factor erythroid 2-related factor 2 (Nrf-2), peroxisome proliferator-activated receptors -γ (PPAR-γ), and heme oxygenase-1 (Hmox-1). In conclusion, TEL's hepatoprotective effects against ALD may be attributable to its anti-inflammatory and anti-oxidant activities which may be in part via the modulation of PPAR-γ/ Nrf-2/ NF-κB crosstalk.

Irbesartan suppresses lipopolysaccharide (LPS)-induced blood-brain barrier (BBB) dysfunction by inhibiting the activation of MLCK/MLC

The basic function of the blood-brain barrier (BBB) is to selectively regulate the infiltration of solutes from the circulating blood into the central nervous system (CNS). Impaired BBB activity is related to brain damage caused by stroke, traumatic injury, neurodegenerative diseases, etc. Comprised of a monolayer of endothelial cells, the integrity of the BBB is determined by the expression of tight junction proteins and the contractile activity of the perijunctional apical actomyosin ring. Irbesartan, an AT1R antagonist, has been widely used for the treatment of hypertension. However, the pharmacological function of Irbesartan in the balance of the BBB is still unknown. In the present study, we performed both in-vivo and in-vitro experiments using lipopolysaccharide (LPS) to explore the mechanism behind the protective effects of Irbesartan against the BBB impairment. The results of our mouse model study revealed that Irbesartan could reduce BBB permeability, restore the expression of Occludin, and suppress the expression of inflammatory mediators, including interleukin-6, monocyte chemoattractant protein-1, and intercellular adhesion molecule-1. Additionally, Irbesartan improved LPS-induced depressive-like behavior. In our in vitro experiments, human brain microvascular endothelial cells (HBMVECs) stimulated with LPS demonstrated decreased endothelial permeability and increased occludin expression in response to Irbesartan treatment. Importantly, we found that the protective effects of Irbesartan were mediated through the NF-κB/MLC/MLCK signaling pathway, as blockage of NF-κB abolished the effects of Irbesartan. Our findings provide a basis for further research into the neuroprotective mechanism of Irbesartan.

Phosphatase and Tensin Homolog Deleted on Chromosome Ten Knockdown Attenuates Cognitive Deficits by Inhibiting Neuroinflammation in a Mouse Model of Perioperative Neurocognitive Disorder

Phosphatase and tensin homolog deleted on chromosome ten (PTEN) is a crucial regulator of neuronal development, neuronal survival, axonal regeneration, and synaptic plasticity. In this study we examined the potential role of PTEN in cognitive function in a mouse model of perioperative neurocognitive disorder (PND). Adult male C57BL/6J mice received intracerebroventricular injections of small interfering RNA (siRNA) against PTEN or control siRNA 3 days prior to exploratory laparotomy (n = 8 per group). A group of healthy mice not undergoing surgery included as additional control. Barnes maze and fear conditioning tests were conducted 7 days after surgery. Mice were then sacrificed to examine the expression of PTEN, AMP-activated protein kinase (AMPK), ionized calcium binding adaptor molecule (Iba)-1, B-cell lymphoma (Bcl)-2, Bcl2-associated X protein (Bax), interleukin (IL)-1β, and tumor necrosis factor (TNF)-α in the hippocampus. The microglial activation was examined by immunohistochemistry using Iba-1 as a microglia maker. Nissl and terminal transferase deoxyuridine triphosphate nick-end labeling (TUNEL) staining were used to measure cell death and apoptosis. In comparison to the healthy controls, surgically treated mice had longer latency to identify the target box in both training and testing sessions in the Barnes maze test and shorter freezing time in the fear conditioning test. Surgically treated mice had increased expression of PTEN, AMPK, Bax, IL-1β, and TNF-α, as well as increasing number of activated microglia and apoptosis neurons in the hippocampus. PTEN knockdown significantly attenuated the behavioral deficits in Barnes maze and fear conditioning tests, as well as over-expression of PTEN, AMPK, Bax, IL-1β, and TNF-α induced by surgery. PTEN knockdown could attenuate cognitive deficits induced by trauma, likely through inhibiting the activation of microglia.

Bis(ethylmaltolato)oxidovanadium (IV) attenuates amyloid-beta-mediated neuroinflammation by inhibiting NF-κB signaling pathway via a PPARγ-dependent mechanism

Neuroinflammation plays a pivotal role in the pathophysiology of neurodegenerative diseases, such as Parkinson's disease and Alzheimer's disease. During brain neuroinflammation, activated microglial cells resulting from amyloid-beta (Aβ) overload trigger toxic proinflammatory responses. Bis(ethylmaltolato)oxidovanadium (BEOV) (IV), an important vanadium compound, has been reported to have anti-diabetic, anti-cancer, and neuroprotective effects, but its anti-inflammatory property has rarely been investigated. In the present study, the inhibitory effects of BEOV on neuroinflammation were revealed in both Aβ-stimulated BV2 microglial cell line and APPswe/PS1E9 transgenic mouse brain. BEOV administration significantly decreased the levels of tumor necrosis factor-α, interleukin-6, interleukin-1β, inducible nitric oxide synthase, and cyclooxygenase-2 both in the hippocampus of APPswe/PS1E9 mice and in the Aβ-stimulated BV2 microglia. Furthermore, BEOV suppressed the Aβ-induced activation of nuclear factor-κB (NF-κB) signaling and upregulated the protein expression level of peroxisome proliferator-activated receptor gamma (PPARγ) in a dose-dependent manner. PPARγ inhibitor GW9662 could eliminate the effect of BEOV on Aβ-induced NF-κB activation and proinflammatory mediator production. Taken altogether, these findings suggested that BEOV ameliorates Aβ-stimulated neuroinflammation by inhibiting NF-κB signaling pathway through a PPARγ-dependent mechanism.

Tackling Alzheimer's Disease with Existing Drugs: A Promising Strategy for Bypassing Obstacles

The unmet need for the development of effective drugs to treat Alzheimer 's disease has been steadily growing, representing a major challenge in drug discovery. In this context, drug repurposing, namely the identification of novel therapeutic indications for approved or investigational compounds, can be seen as an attractive attempt to obtain new medications reducing both the time and the economic burden usually required for research and development programs. In the last years, several classes of drugs have evidenced promising beneficial effects in neurodegenerative diseases, and for some of them, preliminary clinical trials have been started. This review aims to illustrate some of the most recent examples of drugs reprofiled for Alzheimer's disease, considering not only the finding of new uses for existing drugs but also the new hypotheses on disease pathogenesis that could promote previously unconsidered therapeutic regimens. Moreover, some examples of structural modifications performed on existing drugs in order to obtain multifunctional compounds will also be described.

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.

Melatonin-stimulated MSC-derived exosomes improve diabetic wound healing through regulating macrophage M1 and M2 polarization by targeting the PTEN/AKT pathway

Background

After surgery, wound recovery in diabetic patients may be disrupted due to delayed inflammation, which can lead to undesired consequences, and there is currently a lack of effective measures to address this issue. Mesenchymal stem cell (MSC)-derived exosomes (Exo) have been proven to be appropriate candidates for diabetic wound healing through the anti-inflammatory effects. In this study, we investigated whether melatonin (MT)-pretreated MSCs-derived exosomes (MT-Exo) could exert superior effects on diabetic wound healing, and we attempted to elucidate the underlying mechanism.

Methods

For the evaluation of the anti-inflammatory effect of MT-Exo, in vitro and in vivo studies were performed. For in vitro research, we detected the secreted levels of inflammation-related factors, such as IL-1β, TNF-α and IL-10 via ELISA and the relative gene expression of the IL-1β, TNF-α, IL-10, Arg-1 and iNOS via qRT-PCR and investigated the expression of PTEN, AKT and p-AKT by Western blotting. For in vivo study, we established air pouch model and streptozotocin (STZ)-treated diabetic wound model, and evaluated the effect of MT-Exo by flow cytometry, optical imaging, H&E staining, Masson trichrome staining, immunohistochemical staining, immunofluorescence, and qRT-PCR (α-SMA, collagen I and III).

Results

MT-Exo significantly suppressed the pro-inflammatory factors IL-1β and TNF-α and reduced the relative gene expression of IL-1β, TNF-α and iNOS, while promoting the anti-inflammatory factor IL-10 along with increasing the relative expression of IL-10 and Arg-1, compared with that of the PBS, LPS and the Exo groups in vitro. This effect was mediated by the increased ratio of M2 polarization to M1 polarization through upregulating the expression of PTEN and inhibiting the phosphorylation of AKT. Similarly, MT-Exo significantly promoted the healing of diabetic wounds by inhibiting inflammation, thereby further facilitating angiogenesis and collagen synthesis in vivo.

Conclusions

MT-Exo could promote diabetic wound healing by suppressing the inflammatory response, which was achieved by increasing the ratio of M2 polarization to M1 polarization through activating the PTEN/AKT signalling pathway, and the pretreatment of MT was proved to be a promising method for treating diabetic wound healing.

Graphical abstract: MT-Exo promotes diabetic wound healing by regulating M1 and M2 macrophage polarization.

Exosomes derived from mesenchymal stem cells inhibit neointimal hyperplasia by activating the Erk1/2 signalling pathway in rats

Background

Restenosis is a serious problem in patients who have undergone percutaneous transluminal angioplasty. Endothelial injury resulting from surgery can lead to endothelial dysfunction and neointimal formation by inducing aberrant proliferation and migration of vascular smooth muscle cells. Exosomes secreted by mesenchymal stem cells have been a hot topic in cardioprotective research. However, to date, exosomes derived from mesenchymal stem cells (MSC-Exo) have rarely been reported in association with restenosis after artery injury. The aim of this study was to investigate whether MSC-Exo inhibit neointimal hyperplasia in a rat model of carotid artery balloon-induced injury and, if so, to explore the underlying mechanisms.

Methods

Characterization of MSC-Exo immunophenotypes was performed by electron microscopy, nanoparticle tracking analysis and western blot assays. To investigate whether MSC-Exo inhibited neointimal hyperplasia, rats were intravenously injected with normal saline or MSC-Exo after carotid artery balloon-induced injury. Haematoxylin-eosin staining was performed to examine the intimal and media areas. Evans blue dye staining was performed to examine re-endothelialization. Moreover, immunohistochemistry and immunofluorescence were performed to examine the expression of CD31, vWF and α-SMA. To further investigate the involvement of MSC-Exo-induced re-endothelialization, the underlying mechanisms were studied by cell counting kit-8, cell scratch, immunofluorescence and western blot assays.

Results

Our data showed that MSC-Exo were ingested by endothelial cells and that systemic injection of MSC-Exo suppressed neointimal hyperplasia after artery injury. The Evans blue staining results showed that MSC-Exo could accelerate re-endothelialization compared to the saline group. The immunofluorescence and immunohistochemistry results showed that MSC-Exo upregulated the expression of CD31 and vWF but downregulated the expression of α-SMA. Furthermore, MSC-Exo mechanistically facilitated proliferation and migration by activating the Erk1/2 signalling pathway. The western blot results showed that MSC-Exo upregulated the expression of PCNA, Cyclin D1, Vimentin, MMP2 and MMP9 compared to that in the control group. Interestingly, an Erk1/2 inhibitor reversed the expression of the above proteins.

Conclusion

Our data suggest that MSC-Exo can inhibit neointimal hyperplasia after carotid artery injury by accelerating re-endothelialization, which is accompanied by activation of the Erk1/2 signalling pathway. Importantly, our study provides a novel cell-free approach for the treatment of restenosis diseases after intervention.

Dehydroabietic acid alleviates high fat diet-induced insulin resistance and hepatic steatosis through dual activation of PPAR-γ and PPAR-α

Dual-PPAR-α/γ agonist has the dual potentials to improve insulin resistance (IR) and hepatic steatosis associated with obesity. This study aimed to investigate whether dehydroabietic acid (DA), a naturally occurred compound, can bind to and activate both PPAR-γ and PPAR-α to ameliorate IR and hepatic steatosis in high-fat diet (HFD)-fed mice.. We found that DA formed stable hydrogen bonds with the ligand-binding domains of PPAR-γ and PPAR-α. DA treatment also promoted 3T3-L1 differentiation via PPAR-γ activation, and mitochondrial oxygen consumption in HL7702 cells via PPAR-α activation. In HFD-fed mice, DA treatment alleviated glucose intolerance and IR, and reduced hepatic steatosis, liver injury markers (ALT, AST), and lipid accumulation, and promoted mRNA expression of PPAR-γ and PPAR-α signaling elements involved in IR and lipid metabolism in vivo and in vitro, and inhibited mRNA expression of pro-inflammatory factors. Therefore, DA is a dual-PPAR-α/γ and PPAR-γ partial agonist, which can attenuate IR and hepatic steatosis induced by HFD-consumption in mice.