A protease-activated receptor 1 antagonist protects against global cerebral ischemia/reperfusion injury after asphyxial cardiac arrest in rabbits

Cerebral ischemia/reperfusion injury is partially mediated by thrombin, which causes brain damage through protease-activated receptor 1（PAR1）. However, the role and mechanisms underlying the effects of PAR1 activation require further elucidation. Therefore, the present study investigated the effects of the PAR1 antagonist SCH79797 in a rabbit model of global cerebral ischemia induced by cardiac arrest. SCH79797 was intravenously administered 10 minutes after the model was established. Forty-eight hours later, compared with those administered saline, rabbits receiving SCH79797 showed markedly decreased neuronal damage as assessed by serum neuron specific enolase levels and less neurological dysfunction as determined using cerebral performance category scores. Additionally, in the hippocampus, cell apoptosis, polymorphonuclear cell infiltration, and c-Jun levels were decreased, whereas extracellular signal-regulated kinase phosphorylation levels were increased. All of these changes were inhibited by the intravenous administration of the phosphoinositide 3-kinase/Akt pathway inhibitor LY29004（3 mg/kg） 10 minutes before the SCH79797 intervention. These findings suggest that SCH79797 mitigates brain injury via anti-inflammatory and anti-apoptotic effects, possibly by modulating the extracellular signal-regulated kinase, c-Jun N-terminal kinase/c-Jun and phosphoinositide 3-kinase/Akt pathways.

Alterations in serotonin, transient receptor potential channels and protease-activated receptors in rats with irritable bowel syndrome attenuated by Shugan decoction

AIM:To determine the molecular mechanisms of Shugan decoction(SGD) in the regulation of colonic motility and visceral hyperalgesia(VHL) in irritable bowel syndrome(IBS).METHODS:The chemical compounds contained in SGD were measured by high-performance liquid chromatography.A rat model of IBS was induced by chronic water avoidance stress(WAS).The number of fecal pellets was counted after WAS and the pain pressure threshold was measured by colorectal distension.Morphological changes in colonic mucosa were detected by hematoxylin-eosin staining.The contents of tumor necrosis factor(TNF)-αin colonic tissue and calcitonin-gene-related peptide(CGRP)in serum were measured by ELISA.The protein expression of serotonin[5-hydroxytryptamide(5-HT)],serotonin transporter(SERT),chromogranin A(Cg A)and CGRP incolon tissue was measured by immunohistochemistry.RESULTS:SGD inhibited colonic motility dysfunction and VHL in rats with IBS.Blockers of transient receptor potential(TRP)vanilloid 1(TRPV1)(Ruthenium Red)and TRP ankyrin-1(TRPA1)(HC-030031)and activator of protease-activated receptor(PAR)4 increased the pain pressure threshold,whereas activators of PAR2and TRPV4 decreased the pain pressure threshold in rats with IBS.The effect of SGD on pain pressure threshold in these rats was abolished by activators of TRPV1(capsaicin),TRPV4(RN1747),TRPA1(Polygodial)and PAR2(AC55541).In addition,CGRP levels in serum and colonic tissue were both increased in these rats.TNF-αlevel in colonic tissue was also significantly upregulated.However,the levels of 5-HT,SERT and Cg A in colonic tissue were decreased.All these pathological changes in rats with IBS were attenuated by SGD.CONCLUSION:SGD alleviated VHL and attenuated colon motility in IBS,partly by regulating TRPV1,TRPV4,TRPA1,PAR2,5-HT,Cg A and SERT,and reducing CGRP and TNF-αlevel.

Protease-activated receptors in neuropathic pain:an important mediator between neuron and glia

Chronic neuropathic pain is a refractory symptom in clinical practice due to nervous injury or inflammation, and affects millions of people all over the world. Although the neuronal functioning of pain pathways has been studied for many years, the induction and maintenance of this non-adaptive, pathological pain is still poorly understood. Recent evidence indicates that protease-activated receptors (PARs) participate in the initiation and maintenance of neuropathic pain and play a key role in mediating the interactions of nerve cells. Firstly, following nerve injury, alterations in neuron and neuron function induce an abnormal increase of some neurotransmitters and neuromodulators, such as substance P (SP), calcitonin gene-related peptide (CGRP), prostaglandins, kinins, and so on. Such abnormal factors can act on neuron reversely and then induce pain sensation directly, or activate glial cells (astrocytes and microglia) mediated by PARs, which trigger and accelerate the progress of neuropathic pain. Secondly, when the noxious factors invade, glial cells are activated as the first barrier of nervous system and secret many neuroinflammatory factors. These inflammatory factors have effects on PARs (especially PAR1 and PAR2) in the neurons around, and then aggravate the status of pain. Thirdly, in the progress of neuroinflammatory pain, microglia is activated first and initiates the status of pain, and then inflammatory factors and complements from microglia activate astrocytes and maintain or make the pain worse. All of these actions is protective to neurons first, but then turns to a kind of nociception and forms the feeling of pain under the continuous noxious stimuli. Conclusively, PARs may play an important role in the formation and maintenance of chronic pain through mediating the interactions among nerve cells, which may be a novel target in the study and control of neuropathic pain. This article focuses on recent developments of PARs in the progress of neuropathic pain, and provides a framework for addressing the major questions for the future.

Antagonism of Protease-Activated Receptor 4 Protects Against Traumatic Brain Injury by Suppressing Neuroinflammation via Inhibition of Tab2/NF-κB Signaling

Traumatic brain injury(TBI)triggers the activation of the endogenous coagulation mechanism,and a large amount of thrombin is released to curb uncontrollable bleeding through thrombin receptors,also known as protease-activated receptors(PARs).However,thrombin is one of the most critical factors in secondary brain injury.Thus,the PARs may be effective targets against hemorrhagic brain injury.Since the PAR1 antagonist has an increased bleeding risk in clinical practice,PAR4 blockade has been suggested as a more promising treatment.Here,we explored the expression pattern of PAR4 in the brain of mice after TBI,and explored the effect and possible mechanism of BMS-986120(BMS),a novel selective and reversible PAR4 antagonist on secondary brain injury.Treatment with BMS protected against TBI in mice.mRNA-seq analysis,Western blot,and qRT-PCR verification in vitro showed that BMS significantly inhibited thrombin-induced inflammation in astrocytes,and suggested that the Tab2/ERK/NF-κB signaling pathway plays a key role in this process.Our findings provide reliable evidence that blocking PAR4 is a safe and effective intervention for TBI,and suggest that BMS has a potential clinical application in the management of TBI.

Baicalin Attenuates Focal Cerebral Ischemic Reperfusion Injury by Inhibition of Protease-Activated Receptor-1 and Apoptosis

Objective： To investigate the neuro-protective effects of baicaiin in Wistar rats with focal cerebral ischemic reperfusion injury. Methods： Ninety adult male Wistar rats weighing 320-350 g were randomly divided into the following groups （n=5）： （a） sham control group; （b） vehicle group, subjected to middle cerebral artery occlusion and received vehicle intraperitoneally; （c-e） baicalin groups, which were subjected to the middle cerebral artery occlusion and treated with baicalin 25, 50 and 100 mg/kg, respectively. The neurological scores were determined at postoperative 1, 3 and 7 d after the treatment. The expression of protease-activated receptor-1 （PAR-1）, PAR-1 mRNA and Caspase-3 were determined using Western blot, reverse transcription polymerase chain reaction （RT- PCR） analysis and immunohistochemistry, respectively. Results： Significant decrease was noted in the neurological score in the baicalin group compared with that of the vehicle group （P〈0.01）. Additionally, down-regulation of PAR-1 mRNA, PAR-1 and Caspase-3 was observed in the baicalin groups compared with those obtained from the vehicle group （P〈0.01）. Compared with the low-dose baicalin group （25 mg/kg）, remarkable decrease was noted in neurological score, and the expression of PAR-1 mRNA, PAR-1 as well as Caspase-3 in the high-dose group （P〈0.05）. Conclusion： Baicalin showed neuro-protective effects in focal cerebral ischemic reperfusion injury through inhibiting the expression of PAR-1 and apoptosis.

Expression of protease-activated receptors on platelets in healthy individuals

This study aimed to investigate the expression of protease-activated receptors(PARs)on platelets in healthy individuals and preliminarily elucidate physiolo-gical functions of PARs.Thirty healthy volunteers,who did not take any anticoagulants and antiplatelet agents within 10 days before the examination,were recruited.Fasting venous blood(5 mL)was taken from the medial cubital vein in each individual and platelet-rich plasma(PRP)was prepared.The expression of PAR1 mRNA and PAR4 mRNA in PRP was determined by RT-PCR analysis.The results showed that the average levels of PAR1 mRNA and PAR4 mRNA on platelets in healthy individuals were 0.1601�0.0269 and 0.1073�0.0194 respectively.In combination with literature analysis,it was concluded that the thrombin signaling pathway plays a vital role in the development of hemostasis and thrombosis,and the selective PARs antagonist has the potential for extensive application in clinical practice.

Are TrkB receptor agonists the right tool to fulfill the promises for a therapeutic value of the brain-derived neurotrophic factor?

Brain-derived neurotrophic factor signaling via its receptor tro pomyosin receptor kinase B regulates several crucial physiological processes.It has been shown to act in the brain,promoting neuronal survival,growth,and plasticity as well as in the rest of the body where it is involved in regulating for instance aspects of the metabolism.Due to its crucial and very pleiotro pic activity,reduction of brain-derived neurotrophic factor levels and alterations in the brain-derived neurotrophic factor/tropomyosin receptor kinase B signaling have been found to be associated with a wide spectrum of neurological diseases.Howeve r,because of its poor bioavailability and pharmacological properties,brain-derived neurotrophic factor itself has a very low therapeutic value.Moreover,the concomitant binding of exogenous brain-derived neurotrophic factor to the p75 neurotrophin receptor has the potential to elicit several unwanted and deleterious side effects.Therefo re,developing tools and approaches to specifically promote tropomyosin receptor kinase B signaling has become an important goal of translational research.Among the newly developed tools are different categories of tropomyosin receptor kinase B receptor agonist molecules.In this review,we give a comprehensive description of the diffe rent tro pomyosin receptor kinase B receptor agonist drugs developed so far and of the res ults of their application in animal models of several neurological diseases.Moreover,we discuss the main benefits of tropomyosin receptor kinase B receptor agonists,concentrating especially on the new tropomyosin receptor kinase B agonist antibodies.The benefits observed both in vitro and in vivo upon application of tropomyosin receptor kinase B receptor agonist drugs seem to predominantly depend on their general neuroprotective activity and their ability to promote neuronal plasticity.Moreover,tro pomyosin receptor kinase B agonist antibodies have been shown to specifically bind the tropomyosin receptor kinase B receptor and not p75 neurotrophin receptor.Therefore,while,based on the current knowledge,the tropomyosin receptor kinase B receptor agonists do not seem to have the potential to reve rse the disease pathology per se,promoting brainderived neurotrophic factor/tro pomyosin receptor kinase B signaling still has a very high therapeutic relevance.

P2Y1 receptor in Alzheimer’s disease

Alzheimer’s disease is the most frequent form of dementia characterized by the deposition of amyloid-beta plaques and neurofibrillary tangles consisting of hyperphosphorylated tau.Targeting amyloid-beta plaques has been a primary direction for developing Alzheimer’s disease treatments in the last decades.However,existing drugs targeting amyloid-beta plaques have not fully yielded the expected results in the clinic,necessitating the exploration of alternative therapeutic strategies.Increasing evidence unravels that astrocyte morphology and function alter in the brain of Alzheimer’s disease patients,with dysregulated astrocytic purinergic receptors,particularly the P2Y1 receptor,all of which constitute the pathophysiology of Alzheimer’s disease.These receptors are not only crucial for maintaining normal astrocyte function but are also highly implicated in neuroinflammation in Alzheimer’s disease.This review delves into recent insights into the association between P2Y1 receptor and Alzheimer’s disease to underscore the potential neuroprotective role of P2Y1 receptor in Alzheimer’s disease by mitigating neuroinflammation,thus offering promising avenues for developing drugs for Alzheimer’s disease and potentially contributing to the development of more effective treatments.

Melanocortin 3,5 receptors immunohistochemical expression in colonic mucosa of inflammatory bowel disease patients:A matter of disease activity?

BACKGROUND Melanocortin 3 and 5 receptors(i.e.,MC3R and MC5R)belong to the melanocortin family.However,data regarding their role in inflammatory bowel diseases(IBD)are currently unavailable.AIM This study aims to ascertain their expression profiles in the colonic mucosa of Crohn’s disease(CD)and ulcerative colitis(UC),aligning them with IBD disease endoscopic and histologic activity.METHODS Colonic mucosal biopsies from CD/UC patients were sampled,and immunohisto-chemical analyses were conducted to evaluate the expression of MC3R and MC5R.Colonic sampling was performed on both traits with endoscopic scores(Mayo endoscopic score and CD endoscopic index of severity)consistent with inflamed mucosa and not consistent with disease activity(i.e.,normal appearing mucosa).RESULTS In both CD and UC inflamed mucosa,MC3R(CD:+7.7 fold vs normal mucosa,P<0.01;UC:+12 fold vs normal mucosa,P<0.01)and MC5R(CD:+5.5 fold vs normal mucosa,P<0.01;UC:+8.1 fold vs normal mucosa,P<0.01)were significantly more expressed compared to normal mucosa.CONCLUSION MC3R and MC5R are expressed in the colon of IBD patients.Furthermore,expression may differ according to disease endoscopic activity,with a higher degree of expression in the traits affected by disease activity in both CD and UC,suggesting a potential use of these receptors in IBD pharmacology.

Serotonin receptor 2B induces visceral hyperalgesia in rat model and patients with diarrhea-predominant irritable bowel syndrome

BACKGROUND Serotonin receptor 2B(5-HT2B receptor)plays a critical role in many chronic pain conditions.The possible involvement of the 5-HT2B receptor in the altered gut sensation of irritable bowel syndrome with diarrhea(IBS-D)was investigated in the present study.AIM To investigate the possible involvement of 5-HT2B receptor in the altered gut sensation in rat model and patients with IBS-D.METHODS Rectosigmoid biopsies were collected from 18 patients with IBS-D and 10 patients with irritable bowel syndrome with constipation who fulfilled the Rome IV criteria and 15 healthy controls.The expression level of the 5-HT2B receptor in colon tissue was measured using an enzyme-linked immunosorbent assay and correlated with abdominal pain scores.The IBS-D rat model was induced by intracolonic instillation of acetic acid and wrap restraint.Alterations in visceral sensitivity and 5-HT2B receptor and transient receptor potential vanilloid type 1(TRPV1)expression were examined following 5-HT2B receptor antagonist adminis-tration.Changes in visceral sensitivity after administration of the TRPV1 antago-INTRODUCTION Irritable bowel syndrome(IBS)is a chronic functional bowel disorder characterized by recurrent abdominal pain with altered bowel habits that affects approximately 15%of the population worldwide[1].IBS significantly impacts the quality of life of patients.Although the pathogenesis of IBS is not completely understood,the role of abnormal visceral sensitivity in IBS has recently emerged[2,3].5-Hydroxytryptamine(5-HT)is known to play a key role in the physiological states of the gastrointestinal tract.Plasma 5-HT levels in IBS with diarrhea(IBS-D)patients were greater than those in healthy controls[4],suggesting a possible role of 5-HT in the pathogenesis of IBS-D.The serotonin receptor 2(5-HT2 receptor)family comprises three subtypes:5-HT2A,5-HT2B,and 5-HT2c.All 5-HT2 receptors exhibit 46%-50%overall sequence identity,and all of these receptors preferentially bind to Gq/11 to increase inositol phosphates and intracellular calcium mobilization[5].5-HT2B receptors are widely expressed throughout the gut,and experimental evidence suggests that the primary function of 5-HT2B receptors is to mediate contractile responses to 5-HT through its action on smooth muscle[6].The 5-HT2B receptor is localized to both neurons of the myenteric nerve plexus and smooth muscle in the human colon.The 5-HT2B receptor mediates 5-HT-evoked contraction of longitudinal smooth muscle[6].These findings suggest that the 5-HT2B receptor could play an important role in modulating colonic motility,which could affect sensory signaling in the gut.Other laboratories have shown that the 5-HT2B receptor participates in the development of mechanical and formalin-induced hyperalgesia[7,8].A 5-HT2B receptor antagonist reduced 2,4,6-trinitrobenzene sulfonic acid(TNBS)and stress-induced visceral hyperalgesia in rats[9,10].However,the role of the 5-HT2B receptor in IBS-D patients and in acetic acid-and wrap restraint-induced IBS-D rat models was not investigated.

Immunomodulation of Proton-activated G Protein-coupled Receptors in Inflammation

Proton-activated G protein-coupled receptors(GPCRs),initially discovered by Ludwig in 2003,are widely distributed in various tissues.These receptors have been found to modulate the immune system in several inflammatory diseases,including inflammatory bowel disease,atopic dermatitis,and asthma.Proton-activated GPCRs belong to the G protein-coupled receptor family and can detect alternations in extracellular pH.This detection triggers downstream signaling pathways within the cells,ultimately influencing the function of immune cells.In this review,we specifically focused on investigating the immune response of proton-activated GPCRs under inflammatory conditions.

Glucagon-like peptide 1 receptor activation:anti-inflammatory effects in the brain

The glucagon-like peptide 1 is a pleiotropic hormone that has potent insulinotropic effects and is key in treating metabolic diseases such as diabetes and obesity.Glucagon-like peptide 1 exerts its effects by activating a membrane receptor identified in many tissues,including diffe rent brain regions.Glucagon-like peptide 1 activates several signaling pathways related to neuroprotection,like the support of cell growth/survival,enhancement promotion of synapse formation,autophagy,and inhibition of the secretion of proinflammatory cytokines,microglial activation,and apoptosis during neural morphogenesis.The glial cells,including astrocytes and microglia,maintain metabolic homeostasis and defe nse against pathogens in the central nervous system.After brain insult,microglia are the first cells to respond,followed by reactive astrocytosis.These activated cells produce proinflammato ry mediators like cytokines or chemokines to react to the insult.Furthermore,under these circumstances,mic roglia can become chro nically inflammatory by losing their homeostatic molecular signature and,consequently,their functions during many diseases.Several processes promote the development of neurological disorders and influence their pathological evolution:like the formation of protein aggregates,the accumulation of abnormally modified cellular constituents,the formation and release by injured neurons or synapses of molecules that can dampen neural function,and,of critical impo rtance,the dysregulation of inflammato ry control mechanisms.The glucagonlike peptide 1 receptor agonist emerges as a critical tool in treating brain-related inflammatory pathologies,restoring brain cell homeostasis under inflammatory conditions,modulating mic roglia activity,and decreasing the inflammato ry response.This review summarizes recent advances linked to the anti-inflammato ry prope rties of glucagon-like peptide 1 receptor activation in the brain related to multiple sclerosis,Alzheimer’s disease,Parkinson’s disease,vascular dementia,or chronic migraine.

Atropine can induce autophagy independent of the M3 muscarinic acetylcholine receptor

Background: No other effects of atropine other than as an antagonist of muscarinic acetylcholine receptor (mAChR) have been found. Methods: In this study, human kidneyepithelial cells were treated with different physiological regulators. Results: Subsequently, it was found that atropine could significantly induce autophagy as demonstrated by the appearance of autophagosome-like double- or single-membrane vesicles in the cytoplasm ofhost cells and the number of GFP-LC3 dots. In addition, increased conversion of the autophagy marker protein LC3-I and LC3-II and increased p62/SQSTM1 indicatedincomplete autophagy. In addition, atropine induced autophagosome levels in a dose-dependent manner within a certain concentration range in human kidney epithelial cells. In atropine-treated mouse skeletal muscle cells containing nicotinic acetylcholinereceptors and rat cardiac muscle cells containing mAchR, atropine induced autophagy in mouse skeletal muscle cells but not in rat cardiac muscle cells. Furthermore, atropine did not induce autophagy in tissue cells containing mAchR in vivo but did in tissue cells not containing mAchR. Conclusion: This study expands the application and understanding of atropine’s action mechanism in the field of medicine.

Role of bitter contributors and bitter taste receptors:a comprehensive review of their sources,functions and future development

Bitterness,one of the 5“basic tastes”,is usually undesired by humans.However,abundant literature reported that bitter fruits and vegetables have beneficial health effects due to their bitter contributors.This review provided an updated overview of the main bitter contributors of typical bitter fruits and vegetables and their health benefits.The main bitter contributors,including phenolics,terpenoids,alkaloids,amino acids,nucleosides and purines,were summarized.The bioactivities and wide range of beneficial effects of them on anti-cancers,anti-inflammations,anti-microbes,neuroprotection,inhibiting chronic and acute injury in organs,as well as regulating behavior performance and metabolism were reported.Furthermore,not only did the bitter taste receptors(taste receptor type 2 family,T2Rs)show taste effects,but extra-oral T2Rs could also be activated by binding with bitter components,regulating physiological activities via modulating hormone secretion,immunity,metabolism,and cell proliferation.This review provided a new perspective on exploring and explaining the nutrition of bitter foods,revealing the relationship between the functions of bitter contributors from food and T2Rs.Future trends may focus on revealing the possibility of T2Rs being targets for the treatment of diseases,exploring the mechanism of T2Rs mediating the bioactivities,and making bitter foods more acceptable without getting rid of bitter contributors.

Precision targeting in hepatocellular carcinoma:Exploring ligandreceptor mediated nanotherapy

Hepatocellular carcinoma(HCC)is the most common primary liver cancer and poses a major challenge to global health due to its high morbidity and mortality.Conventional chemotherapy is usually targeted to patients with intermediate to advanced stages,but it is often ineffective and suffers from problems such as multidrug resistance,rapid drug clearance,nonspecific targeting,high side effects,and low drug accumulation in tumor cells.In response to these limitations,recent advances in nanoparticle-mediated targeted drug delivery technologies have emerged as breakthrough approaches for the treatment of HCC.This review focuses on recent advances in nanoparticle-based targeted drug delivery systems,with special attention to various receptors overexpressed on HCC cells.These receptors are key to enhancing the specificity and efficacy of nanoparticle delivery and represent a new paradigm for actively targeting and combating HCC.We comprehensively summarize the current understanding of these receptors,their role in nanoparticle targeting,and the impact of such targeted therapies on HCC.By gaining a deeper understanding of the receptor-mediated mechanisms of these innovative therapies,more effective and precise treatment of HCC can be achieved.

Cholecystokinin and cholecystokinin-A receptor: An attractive treatment strategy for biliary dyskinesia?

Biliary dyskinesia is a relatively common gastrointestinal disease that is increas-ing in incidence as living standards improve.However,its underlying pathogenesis remains unclear,hindering the development of therapeutic drugs.Recently,“Expression and functional study of cholecystokinin-A receptors on the interstitial Cajal-like cells of the guinea pig common bile duct”demonstrated that cholecystokinin(CCK)regulates the contractile function of the common bile duct through interaction with the CCK-A receptor in interstitial Cajal-like cells,contributing to improving the academic understanding of biliary tract dynamics and providing emerging directions for the pathogenesis and clinical management of biliary dyskinesia.This letter provides a brief overview of the role of CCK and CCK-A receptors in biliary dyskinesia from the perspective of animal experiments and clinical studies,and discusses prospects and challenges for the clinical application of CCK and CCK-A receptors as potential therapeutic targets.

Practical guide:Glucagon-like peptide-1 and dual glucosedependent insulinotropic polypeptide and glucagon-like peptide-1 receptor agonists in diabetes mellitus

Practical guide:Glucagon-like peptide-1 and dual glucosedependent insulinotropic polypeptide and glucagon-like peptide-1 receptor agonists in diabetes mellitus common second-line choice after metformin for treating T2DM.Various considerations can make selecting and switching between different GLP-1 RAs challenging.Our study aims to provide a comprehensive guide for the usage of GLP-1 RAs and dual GIP and GLP-1 RAs for the management of T2DM.

Receptor tyrosine kinase-like orphan receptor 1:A novel antitumor target in gastrointestinal cancers

Receptor tyrosine kinase-like orphan receptor 1(ROR1)is a member of the type I receptor tyrosine kinase family.ROR1 is pivotal in embryonic development and cancer,and serves as a biomarker and therapeutic target.It has soluble and membrane-bound subtypes,with the latter highly expressed in tumors.ROR1 is conserved throughout evolution and may play a role in the development of gastrointestinal cancer through multiple signaling pathways and molecular mechanisms.Studies suggest that overexpression of ROR1 may increase tumor invasiveness and metastasis.Additionally,ROR1 may regulate the cell cycle,stem cell characteristics,and interact with other signaling pathways to affect cancer progression.This review explores the structure,expression and role of ROR1 in the development of gastrointestinal cancers.It discusses current antitumor strategies,outlining challenges and prospects for treatment.

Exploring the vital role of microglial membrane receptors in Alzheimer’s disease pathogenesis: a comprehensive review

Neurodegenerative diseases constitute a broad category of diseases caused by the degeneration of the neurons.They are mainly manifested by the gradual loss of neuron structure and function and eventually can cause death or loss of neurons.As the global population ages rapidly,increased people are being diagnosed with neurodegenerative diseases.It has been established that the onset of Alzheimer’s disease(AD)is closely linked with increasing age and its major pathological features include amyloid-beta plaques(Aβ),Tau hyperphosphorylation,Neurofibrillary tangles(NFTs),neuronal death as well as synaptic loss.The involvement of microglia is crucial in the pathogenesis and progression of AD and exhibits a dual role.For instance,in the early stage of AD,microglia surface membrane proteins or receptors can participate in immunophagocytosis,and anti-inflammatory functions and act as a physical barrier after recognizing various ligands such as Aβand NFTs.However,in the later stage of the disease,membrane receptors on the surface of microglia can cause its activation to release a substantial quantity of pro-inflammatory factors.Which can amplify the neuroinflammatory response.The rapid decline of normal immune phagocytosis can result in the continuous accumulation of abnormal proteins,leading to neuronal dysfunction and destruction of the formed physical barrier as well as the neurovascular microenvironment.It can also increase the transformation of microglia from anti-inflammatory phenotype M2 to pro-inflammatory phenotype M1,induce severe neuronal injury or apoptosis,and aggravate the progression of AD.Due to few articles have focused on the AD-related membrane protein receptors on microglia,thus in this paper,we have reviewed several representative microglial membrane proteins or receptors about their specific roles and functions implicated in AD,and expect that there will be more in-depth research and scientific research results in the treatment of AD by targeted regulation of microglia membrane protein receptors in the future.