Microglial response to aging and neuroinflammation in the development of neurodegenerative diseases

Cellular senescence and chronic inflammation in response to aging are considered to be indicators of brain aging;they have a great impact on the aging process and are the main risk factors for neurodegeneration.Reviewing the microglial response to aging and neuroinflammation in neurodegenerative diseases will help understand the importance of microglia in neurodegenerative diseases.This review describes the origin and function of microglia and focuses on the role of different states of the microglial response to aging and chronic inflammation on the occurrence and development of neurodegenerative diseases,including Alzheimer's disease,Huntington's chorea,and Parkinson's disease.This review also describes the potential benefits of treating neurodegenerative diseases by modulating changes in microglial states.Therefore,inducing a shift from the neurotoxic to neuroprotective microglial state in neurodegenerative diseases induced by aging and chronic inflammation holds promise for the treatment of neurodegenerative diseases in the future.

The role of exosomes in adult neurogenesis:implications for neurodegenerative diseases

Exosomes are cup-shaped extracellular vesicles with a lipid bilayer that is approximately 30 to 200 nm in thickness.Exosomes are widely distributed in a range of body fluids,including urine,blood,milk,and saliva.Exosomes exert biological function by transporting factors between different cells and by regulating biological pathways in recipient cells.As an important form of intercellular communication,exosomes are increasingly being investigated due to their ability to transfer bioactive molecules such as lipids,proteins,mRNAs,and microRNAs between cells,and because they can regulate physiological and pathological processes in the central nervous system.Adult neurogenesis is a multistage process by which new neurons are generated and migrate to be integrated into existing neuronal circuits.In the adult brain,neurogenesis is mainly localized in two specialized niches:the subventricular zone adjacent to the lateral ventricles and the subgranular zone of the dentate gyrus.An increasing body of evidence indicates that adult neurogenesis is tightly controlled by environmental conditions with the niches.In recent studies,exosomes released from different sources of cells were shown to play an active role in regulating neurogenesis both in vitro and in vivo,thereby participating in the progression of neurodegenerative disorders in patients and in various disease models.Here,we provide a state-of-the-art synopsis of existing research that aimed to identify the diverse components of exosome cargoes and elucidate the therapeutic potential of exosomal contents in the regulation of neurogenesis in several neurodegenerative diseases.We emphasize that exosomal cargoes could serve as a potential biomarker to monitor functional neurogenesis in adults.In addition,exosomes can also be considered as a novel therapeutic approach to treat various neurodegenerative disorders by improving endogenous neurogenesis to mitigate neuronal loss in the central nervous system.

Unraveling the gut-brain axis:the impact of steroid hormones and nutrition on Parkinson's disease

This comprehensive review explores the intricate relationship between nutrition,the gut microbiome,steroid hormones,and Parkinson's disease within the context of the gut-brain axis.The gut-brain axis plays a pivotal role in neurodegenerative diseases like Parkinson's disease,encompassing diverse components such as the gut microbiota,immune system,metabolism,and neural pathways.The gut microbiome,profoundly influenced by dietary factors,emerges as a key player.Nutrition during the first 1000 days of life shapes the gut microbiota composition,influencing immune responses and impacting both child development and adult health.High-fat,high-sugar diets can disrupt this delicate balance,contributing to inflammation and immune dysfunction.Exploring nutritional strategies,the Mediterranean diet's anti-inflammatory and antioxidant properties show promise in reducing Parkinson's disease risk.Microbiome-targeted dietary approaches and the ketogenic diet hold the potential in improving brain disorders.Beyond nutrition,emerging research uncovers potential interactions between steroid hormones,nutrition,and Parkinson's disease.Progesterone,with its anti-inflammatory properties and presence in the nervous system,offers a novel option for Parkinson's disease therapy.Its ability to enhance neuroprotection within the enteric nervous system presents exciting prospects.The review addresses the hypothesis thatα-synuclein aggregates originate from the gut and may enter the brain via the vagus nerve.Gastrointestinal symptoms preceding motor symptoms support this hypothesis.Dysfunctional gut-brain signaling during gut dysbiosis contributes to inflammation and neurotransmitter imbalances,emphasizing the potential of microbiota-based interventions.In summary,this review uncovers the complex web of interactions between nutrition,the gut microbiome,steroid hormones,and Parkinson's disease within the gut-brain axis framework.Understanding these connections not only offers novel therapeutic insights but also illuminates the origins of neurodegenerative diseases such as Parkinson's disease.

Neuroprotective effects of chaperone-mediated autophagy in neurodegenerative diseases

Chaperone-mediated autophagy is one of three types of autophagy and is characterized by the selective degradation of proteins.Chaperone-mediated autophagy contributes to energy balance and helps maintain cellular homeostasis,while providing nutrients and support for cell survival.Chaperone-mediated autophagy activity can be detected in almost all cells,including neurons.Owing to the extreme sensitivity of neurons to their environmental changes,maintaining neuronal homeostasis is critical for neuronal growth and survival.Chaperone-mediated autophagy dysfunction is closely related to central nervous system diseases.It has been shown that neuronal damage and cell death are accompanied by chaperone-mediated autophagy dysfunction.Under certain conditions,regulation of chaperone-mediated autophagy activity attenuates neurotoxicity.In this paper,we review the changes in chaperone-mediated autophagy in neurodegenerative diseases,brain injury,glioma,and autoimmune diseases.We also summarize the most recent research progress on chaperone-mediated autophagy regulation and discuss the potential of chaperone-mediated autophagy as a therapeutic target for central nervous system diseases.

Effects of proton pump inhibitors on inflammatory bowel disease:An updated review

Inflammatory bowel disease(IBD)is believed to be caused by various factors,including abnormalities in disease susceptibility genes,environmental factors,immune factors,and intestinal bacteria.Proton pump inhibitors(PPIs)are the primary drugs used to treat acid-related diseases.They are also commonly prescribed to patients with IBD.Recent studies have suggested a potential association between the use of certain medications,such as PPIs,and the occurrence and progression of IBD.In this review,we summarize the potential impact of PPIs on IBD and analyze the underlying mechanisms.Our findings may provide insights for conducting further investigations into the effects of PPIs on IBD and serve as an important reminder for physicians to exercise caution when prescribing PPIs to patients with IBD.

Antisense therapy:a potential breakthrough in the treatment of neurodegenerative diseases

Neurodegenerative diseases are a group of disorders characterized by the progressive degeneration of neurons in the central or peripheral nervous system.Currently,there is no cure for neurodegenerative diseases and this means a heavy burden for patients and the health system worldwide.Therefore,it is necessary to find new therapeutic approaches,and antisense therapies offer this possibility,having the great advantage of not modifying cellular genome and potentially being safer.Many preclinical and clinical studies aim to test the safety and effectiveness of antisense therapies in the treatment of neurodegenerative diseases.The objective of this review is to summarize the recent advances in the development of these new technologies to treat the most common neurodegenerative diseases,with a focus on those antisense therapies that have already received the approval of the U.S.Food and Drug Administration.

Emerging roles of exosomes in oral diseases progression

Oral diseases, such as periodontitis, salivary gland diseases, and oral cancers, significantly challenge health conditions due to their detrimental effects on patient's digestive functions, pronunciation, and esthetic demands. Delayed diagnosis and non-targeted treatment profoundly influence patients' prognosis and quality of life. The exploration of innovative approaches for early detection and precise treatment represents a promising frontier in oral medicine.

Alanine aminotransferase predicts incident steatotic liver disease of metabolic etiology: Long life to the old biomarker!

Alanine aminotransferase(ALT)serum levels increase because of hepatocellular damage.Metabolic dysfunction-associated fatty liver disease(MAFLD),which identifies steatotic liver disease(SLD)associated with≥2 metabolic abnormalities,has prominent sexual differences.The Metabolic Syndrome defines a cluster comprising abdominal obesity,altered glucose metabolism,dyslipidemia,and hypertension.Male sex,body mass index,glucose,lipids,ferritin,hypertension,and age independently predict ALT levels among blood donors.Over the last few decades,the reference range of ALT levels has been animatedly debated owing to attempts to update sex-specific reference ranges.With this backset,Chen et al have recently published a study which has two main findings.First,>80%of indi-viduals with MAFLD had normal ALT levels.Second,there was a linear increa-sing trend in the association between cumulative excess high-normal ALT levels and the rate of incident MAFLD.This study has biologically credible findings.However,it inaccurately considered sex differences in the MAFLD arena.Therefore,future studies on SLD owing to metabolic dysfunction should adopt locally determined and prospectively validated reference ranges of ALT and carefully consider sex differences in liver enzymes and MAFLD pathobiology.

ATP-binding cassette transporters as possible targets for the intervention of neurodegenerative diseases

ATP-binding cassette(ABC)transporters are ubiquitous membrane-bound proteins that are responsible for the translocation of a broad spectrum of substrates across cellular membranes,including lipids,amino acids,nucleosides,sugars,and xenobiotics.Interestingly,ABC transporters are highly expressed in the brain.While their functions in the brain still need to be elucidated,several members are implicated in the pathogenesis of neurodegenerative diseases,including Alzheimer’s disease(AD),Parkinson’s disease(PD),and frontotemporal dementia.In this perspective,we will review current knowledge of ABC transporters in the central nervous system in terms of physiological functions and pathology in neurodegeneration.Furthermore,we will explore the possibilities of ABC transporters as potential targets in the development of therapeutics for neurodegenerative diseases.

Clinical associations of corneal neuromas with ocular surface diseases

Corneal neuromas,also termed microneuromas,refer to microscopic,irregula rly-shaped enlargements of terminal subbasal nerve endings at sites of nerve damage or injury.The formation of corneal neuromas results from damage to corneal nerves,such as following corneal pathology or corneal or intraocular surge ries.Initially,denervated areas of sensory nerve fibers become invaded by sprouts of intact sensory nerve fibers,and later injured axons regenerate and new sprouts called neuromas develop.In recent years,analysis of corneal nerve abnormalities including corneal neuromas which can be identified using in vivo confocal microscopy,a non-invasive imaging technique with microscopic resolution,has been used to evaluate corneal neuropathy and ocular surface dysfunction.Corneal neuromas have been shown to be associated with clinical symptoms of discomfort and dryness of eyes,and are a promising surrogate biomarker for ocular surface diseases,such as neuropathic corneal pain,dry eye disease,diabetic corneal neuropathy,neurotrophic keratopathy,Sjogren's syndrome,bullous keratopathy,post-refra ctive surgery,and others.In this review,we have summarized the current literature on the association between these ocular surface diseases and the presentation of corneal microneuromas,as well as elaborated on their pathogenesis,visualization via in vivo confocal microscopy,and utility in monitoring treatment efficacy.As current quantitative analysis on neuromas mainly relies on manual annotation and quantification,which is user-dependent and labor-intensive,future direction includes the development of artificial intelligence software to identify and quantify these potential imaging biomarkers in a more automated and sensitive manner,allowing it to be applied in clinical settings more efficiently.Combining imaging and molecular biomarkers may also help elucidate the associations between corneal neuromas and ocular surface diseases.

Nuance of inward rectifying potassium(Kir)channel dysfunctions in neurodegenerative diseases

Neurodegenerative disorders are highly prevalent and diverse in nature.Their manifestation largely depends on the cell types involved,with aberrant inflammatory episodes progressively inducing a constellation of phenotypes that are classified into specific diseases based on their neuropathological traits.The two most prevalent neurodegenerative diseases worldwide,Alzheimer’s disease(AD)and Parkinson’s disease(PD),for example,share notable similarities,yet they differ in terms of the specific cell types lost within the central nervous system(CNS).The significant and progressive loss of cortical and certain subcortical neurons in various regions is a major defining trait of AD.In contrast,the specific loss of dopaminergic neurons(DA)within the substantial nigra pars compacta(SNpc)is sufficient to cause motor symptoms associated with PD.Another devastating condition arising from neurodegeneration within the CNS,amyotrophic lateral sclerosis(ALS),results in the progressive death of upper and lower motor neurons.This degeneration originates in oligodendrocytes,whose defective myelination abilities lead to the denervation of the anterior horn,aggravating motor neuron death.

Association between physical activity and risk of gastroesophageal reflux disease:A systematic review and meta-analysis

Background:Lifestyle plays an important role in preventing and managing gastroesophageal reflux disease(GERD).In response to the conflicting results in previous studies,we performed a systematic review and meta-analysis to investigate this association.Methods:Relevant studies published until January 2023 were retrieved from 6 databases,and the prevalence of symptomatic gastroesophageal reflux(GER)or GERD was determined from the original studies.A random effects model was employed to meta-analyze the association by computing the pooled relative risk(RR)with 95%confidence intervals(95%CIs).Furthermore,subgroup and dose-response analyses were performed to explore subgroup differences and the association between cumulative physical activity(PA)time and GERD.Results:This meta-analysis included 33 studies comprising 242,850 participants.A significant negative association was observed between PA and the prevalence of symptomatic GER(RR=0.74,95%CI:0.66-0.83;p<0.01)or GERD(RR=0.80,95%CI:0.76-0.84;p<0.01),suggesting that engaging in PA might confer a protective benefit against GERD.Subgroup analyses consistently indicated the presence of this association across nearly all subgroups,particularly among the older individuals(RR_(<40 years):RR_(≥40 years)=0.85:0.69,p<0.01)and smokers(RR_(smoker):RR_(non-smoker)=0.67:0.82,p=0.03).Furthermore,a dose-response analysis revealed that individuals who engaged in 150 min of PA per week had a 72.09%lower risk of developing GERD.Conclusion:Maintaining high levels of PA decreased the risk of GERD,particularly among older adults and smokers.Meeting the recommended PA level of 150 min per week may significantly decrease the prevalence of GERD.

Crohn’s disease as the intestinal manifestation of pan-lymphatic dysfunction:An exploratory proposal based on basic and clinical data

Crohn’s disease(CD)is caused by immune,environmental,and genetic factors.It can involve the entire gastrointestinal tract,and although its prevalence is rapidly increasing its etiology remains unclear.Emerging biological and small-molecule drugs have advanced the treatment of CD;however,a considerable proportion of patients are non-responsive to all known drugs.To achieve a breakthrough in this field,innovations that could guide the further development of effective therapies are of utmost urgency.In this review,we first propose the innovative concept of pan-lymphatic dysfunction for the general distribution of lymphatic dysfunction in various diseases,and suggest that CD is the intestinal manifestation of pan-lymphatic dysfunction based on basic and clinical preliminary data.The supporting evidence is fully summarized,including the existence of lymphatic system dysfunction,recognition of the inside-out model,disorders of immune cells,changes in cell plasticity,partial overlap of the underlying mechanisms,and common gut-derived fatty and bile acid metabolism.Another benefit of this novel concept is that it proposes adopting the zebrafish model for studying intestinal diseases,especially CD,as this model is good at presenting and mimicking lymphatic dysfunction.More importantly,the ensuing focus on improving lymphatic function may lead to novel and promising therapeutic strategies for CD.

Correlation between the gut microbiome and neurodegenerative diseases:a review of metagenomics evidence

A growing body of evidence suggests that the gut microbiota contributes to the development of neurodegenerative diseases via the microbiota-gut-brain axis.As a contributing factor,microbiota dysbiosis always occurs in pathological changes of neurodegenerative diseases,such as Alzheimer’s disease,Parkinson’s disease,and amyotrophic lateral sclerosis.High-throughput sequencing technology has helped to reveal that the bidirectional communication between the central nervous system and the enteric nervous system is facilitated by the microbiota’s diverse microorganisms,and for both neuroimmune and neuroendocrine systems.Here,we summarize the bioinformatics analysis and wet-biology validation for the gut metagenomics in neurodegenerative diseases,with an emphasis on multi-omics studies and the gut virome.The pathogen-associated signaling biomarkers for identifying brain disorders and potential therapeutic targets are also elucidated.Finally,we discuss the role of diet,prebiotics,probiotics,postbiotics and exercise interventions in remodeling the microbiome and reducing the symptoms of neurodegenerative diseases.

Back to the drawing board:Overview of the next generation of combination therapy for inflammatory bowel disease

Inflammatory bowel disease(IBD)is entering a potentially new era of combined therapeutics.Triantafillidis et al provide an insightful review of the current state of combination therapy,with a focus on the use of a combined biologic and immunomodulator,as well as emerging data on the future potential of dual-biologic therapy(DBT).While current evidence for DBT is limited,encouraging safety profiles and ongoing trials suggest a brighter future for this approach.The importance of controlled trials should be stressed in establishing new treatment paradigms.Ongoing prospective randomized trials of DBT and perhaps future combinations of biologics and small molecule therapies will hopefully guide the next generation of IBD care.

Activation of autophagy by Citri Reticulatae Semen extract ameliorates amyloid-beta-induced cell death and cognition deficits in Alzheimer’s disease

Amyloid-beta-induced neuronal cell death contributes to cognitive decline in Alzheimer’s disease.Citri Reticulatae Semen has diverse beneficial effects on neurodegenerative diseases,including Parkinson’s and Huntington’s diseases,however,the effect of Citri Reticulatae Semen on Alzheimer’s disease remains unelucidated.In the current study,the anti-apoptotic and autophagic roles of Citri Reticulatae Semen extract on amyloid-beta-induced apoptosis in PC12 cells were first investigated.Citri Reticulatae Semen extract protected PC12 cells from amyloid-beta-induced apoptosis by attenuating the Bax/Bcl-2 ratio via activation of autophagy.In addition,Citri Reticulatae Semen extract was confirmed to bind amyloid-beta as revealed by biolayer interferometry in vitro,and suppress amyloid-beta-induced pathology such as paralysis,in a transgenic Caenorhabditis elegans in vivo model.Moreover,genetically defective Caenorhabditis elegans further confirmed that the neuroprotective effect of Citri Reticulatae Semen extract was autophagy-dependent.Most importantly,Citri Reticulatae Semen extract was confirmed to improve cognitive impairment,neuronal injury and amyloid-beta burden in 3×Tg Alzheimer’s disease mice.As revealed by both in vitro and in vivo models,these results suggest that Citri Reticulatae Semen extract is a potential natural therapeutic agent for Alzheimer’s disease via its neuroprotective autophagic effects.

Effects of mesenchymal stem cell on dopaminergic neurons,motor and memory functions in animal models of Parkinson's disease:a systematic review and meta-analysis

Parkinson’s disease is chara cterized by the loss of dopaminergic neurons in the substantia nigra pars com pacta,and although restoring striatal dopamine levels may improve symptoms,no treatment can cure or reve rse the disease itself.Stem cell therapy has a regenerative effect and is being actively studied as a candidate for the treatment of Parkinson’s disease.Mesenchymal stem cells are considered a promising option due to fewer ethical concerns,a lower risk of immune rejection,and a lower risk of teratogenicity.We performed a meta-analysis to evaluate the therapeutic effects of mesenchymal stem cells and their derivatives on motor function,memory,and preservation of dopamine rgic neurons in a Parkinson’s disease animal model.We searched bibliographic databases(PubMed/MEDLINE,Embase,CENTRAL,Scopus,and Web of Science)to identify articles and included only pee r-reviewed in vivo interve ntional animal studies published in any language through J une 28,2023.The study utilized the random-effect model to estimate the 95%confidence intervals(CI)of the standard mean differences(SMD)between the treatment and control groups.We use the systematic review center for laboratory animal expe rimentation’s risk of bias tool and the collaborative approach to meta-analysis and review of animal studies checklist for study quality assessment.A total of 33studies with data from 840 Parkinson’s disease model animals were included in the meta-analysis.Treatment with mesenchymal stem cells significantly improved motor function as assessed by the amphetamine-induced rotational test.Among the stem cell types,the bone marrow MSCs with neurotrophic factor group showed la rgest effect size(SMD[95%CI]=-6.21[-9.50 to-2.93],P=0.0001,I^(2)=0.0%).The stem cell treatment group had significantly more tyrosine hydroxylase positive dopamine rgic neurons in the striatum([95%CI]=1.04[0.59 to 1.49],P=0.0001,I^(2)=65.1%)and substantia nigra(SMD[95%CI]=1.38[0.89 to 1.87],P=0.0001,I^(2)=75.3%),indicating a protective effect on dopaminergic neurons.Subgroup analysis of the amphetamine-induced rotation test showed a significant reduction only in the intracranial-striatum route(SMD[95%CI]=-2.59[-3.25 to-1.94],P=0.0001,I^(2)=74.4%).The memory test showed significant improvement only in the intravenous route(SMD[95%CI]=4.80[1.84 to 7.76],P=0.027,I^(2)=79.6%).Mesenchymal stem cells have been shown to positively impact motor function and memory function and protect dopaminergic neurons in preclinical models of Parkinson’s disease.Further research is required to determine the optimal stem cell types,modifications,transplanted cell numbe rs,and delivery methods for these protocols.

Effect of Aspergillus niger prolyl endopeptidase in patients with celiac disease on a long-term gluten-free diet

BACKGROUND The gluten-free diet(GFD)has limitations,and there is intense research in the development of adjuvant therapies.AIM To examine the effects of orally administered Aspergillus niger prolyl endopeptidase protease(AN-PEP)on inadvertent gluten exposure and symptom prevention in adult celiac disease(CeD)patients following their usual GFD.METHODS This was an exploratory,double-blind,randomized,placebo-controlled trial that enrolled CeD patients on a long-term GFD.After a 4-wk run-in period,patients were randomized to 4 wk of two AN-PEP capsules(GliadinX;AVI Research,LLC,United States)at each of three meals per day or placebo.Outcome endpoints were:(1)Average weekly stool gluten immunogenic peptides(GIP)between the run-in and end of treatments and between AN-PEP and placebo;(2)celiac symptom index(CSI);(3)CeD-specific serology;and(4)quality of life.Stool samples were collected for GIP testing by ELISA every Tuesday and Friday during run-ins and treatments.RESULTS Forty patients were randomized for the intention-to-treat analysis,and three were excluded from the per-protocol assessment.Overall,628/640(98.1%)stool samples were collected.GIP was undetectable(<0.08μg/g)in 65.6%of samples,and no differences between treatment arms were detected.Only 0.5%of samples had GIP concentrations sufficiently high(>0.32μg/g)to potentially cause mucosal damage.Median GIP concentration in the AN-PEP arm was 44.7%lower than in the run-in period.One-third of patients exhibiting GIP>0.08μg/g during run-in had lower or undetectable GIP after AN-PEP treatment.Compared with the run-in period,the proportion of symptomatic patients(CSI>38)in the AN-PEP arm was significantly lower(P<0.03).AN-PEP did not result in changes in specific serologies.CONCLUSION This exploratory study conducted in a real-life setting revealed high adherence to the GFD.The AN-PEP treatment did not significantly reduce the overall GIP stool concentration.However,given the observation of a significantly lower prevalence of patients with severe symptoms in the AN-PEP arm,further clinical research is warranted.

A systematic review of salivary biomarkers in Parkinson's disease

The search fo r reliable and easily accessible biomarkers in Parkinson's disease is receiving a growing emphasis,to detect neurodegeneration from the prodromal phase and to enforce disease-modifying therapies.Despite the need for non-invasively accessible biomarke rs,the majo rity of the studies have pointed to cerebrospinal fluid or peripheral biopsies biomarkers,which require invasive collection procedures.Saliva represents an easily accessible biofluid and an incredibly wide source of molecular biomarkers.In the present study,after presenting the morphological and biological bases for looking at saliva in the search of biomarkers for Parkinson's disease,we systematically reviewed the results achieved so far in the saliva of different cohorts of Parkinson's disease patients.A comprehensive literature search on PubMed and SCOPUS led to the discovery of 289articles.After screening and exclusion,34 relevant articles were derived fo r systematic review.Alpha-synuclein,the histopathological hallmark of Parkinson's disease,has been the most investigated Parkinson's disease biomarker in saliva,with oligomeric alphasynuclein consistently found increased in Parkinson's disease patients in comparison to healthy controls,while conflicting results have been reported regarding the levels of total alpha-synuclein and phosphorylated alpha-synuclein,and few studies described an increased oligomeric alpha-synuclein/total alpha-synuclein ratio in Parkinson's disease.Beyond alpha-synuclein,other biomarkers to rgeting diffe rent molecular pathways have been explored in the saliva of Parkinson's disease patients:total tau,phosphorylated tau,amyloid-β1-42(pathological protein aggregation biomarkers);DJ-1,heme-oxygenase-l,metabolites(alte red energy homeostasis biomarkers);MAPLC-3beta(aberrant proteostasis biomarker);cortisol,tumor necrosis factor-alpha(inflammation biomarkers);DNA methylation,miRNA(DNA/RNA defects biomarkers);acetylcholinesterase activity(synaptic and neuronal network dysfunction biomarkers);Raman spectra,proteome,and caffeine.Despite a few studies investigating biomarkers to rgeting molecular pathways different from alpha-synuclein in Parkinson's disease,these results should be replicated and observed in studies on larger cohorts,considering the potential role of these biomarkers in determining the molecular variance among Parkinson's disease subtypes.Although the need fo r standardization in sample collection and processing,salivary-based biomarkers studies have reported encouraging results,calling for large-scale longitudinal studies and multicentric assessments,given the great molecular potentials and the non-invasive accessibility of saliva.

Role of gut-liver axis and glucagon-like peptide-1 receptor agonists in the treatment of metabolic dysfunction-associated fatty liver disease

Metabolic dysfunction-associated fatty liver disease(MAFLD)is a hepatic manifestation of the metabolic syndrome.It is one of the most common liver diseases worldwide and shows increasing prevalence rates in most countries.MAFLD is a progressive disease with the most severe cases presenting as advanced fibrosis or cirrhosis with an increased risk of hepatocellular carcinoma.Gut microbiota play a significant role in the pathogenesis and progression of MAFLD by disrupting the gut-liver axis.The mechanisms involved in maintaining gut-liver axis homeostasis are complex.One critical aspect involves preserving an appropriate intestinal barrier permeability and levels of intestinal lumen metabolites to ensure gutliver axis functionality.An increase in intestinal barrier permeability induces metabolic endotoxemia that leads to steatohepatitis.Moreover,alterations in the absorption of various metabolites can affect liver metabolism and induce liver steatosis and fibrosis.Glucagon-like peptide-1 receptor agonists(GLP-1 RAs)are a class of drugs developed for the treatment of type 2 diabetes mellitus.They are also commonly used to combat obesity and have been proven to be effective in reversing hepatic steatosis.The mechanisms reported to be involved in this effect include an improved regulation of glycemia,reduced lipid synthesis,β-oxidation of free fatty acids,and induction of autophagy in hepatic cells.Recently,multiple peptide receptor agonists have been introduced and are expected to increase the effectiveness of the treatment.A modulation of gut microbiota has also been observed with the use of these drugs that may contribute to the amelioration of MAFLD.This review presents the current understanding of the role of the gutliver axis in the development of MAFLD and use of members of the GLP-1 RA family as pleiotropic agents in the treatment of MAFLD.