Age-related rhesus macaque models of COVID-19

Background:Since December 2019,an outbreak of the Corona Virus disease 2019(COVID-19)caused by severe acute respiratory syndrome coronavirus(SARS-CoV-2)in Wuhan,China,has become a public health emergency of international concern.The high fatality of aged cases caused by SARS-CoV-2 was a need to explore the possible age-related phenomena with non-human primate models.Methods:Three 3-5 years old and two 15 years old rhesus macaques were intratracheally infected with SARS-CoV-2,and then analyzed by clinical signs,viral replication,chest X-ray,histopathological changes and immune response.Results:Viral replication of nasopharyngeal swabs,anal swabs and lung in old monkeys was more active than that in young monkeys for 14 days after SARS-CoV-2 challenge.Monkeys developed typical interstitial pneumonia characterized by thickened alveolar septum accompanied with inflammation and edema,notably,old monkeys exhibited diffuse severe interstitial pneumonia.Viral antigens were detected mainly in alveolar epithelial cells and macrophages.Conclusion:SARS-CoV-2 caused more severe interstitial pneumonia in old monkeys than that in young monkeys.Rhesus macaque models infected with SARS-CoV-2 provided insight into the pathogenic mechanism and facilitated the development of vaccines and therapeutics against SARS-CoV-2 infection.

Microarray microRNA profiling of urinary exosomes in a 5XFAD mouse model of Alzheimer’s disease

Background:Alzheimer's disease(AD)is an incurable and irreversible neurodegen-erative disease,without a clear pathogenesis.Therefore,identification of candidates before amyloid-βplaque(Aβ)deposition proceeds is of major significance for earlier intervention in AD.Methods:To explore the potential noninvasive earlier biomarkers of AD in a 5XFAD mouse model,microRNAs(miRNAs)from urinary exosomes in 1-month-old pre-Aβaccumulation 5XFAD mice models and their littermate controls were profiled by mi-croarray analysis.The differentially expressed miRNAs were further analyzed via droplet digital PCR(ddPCR).Results:Microarray analysis demonstrated that 48 differentially expressed miRNAs(18 upregulated and 30 downregulated),of which six miRNAs-miR-196b-5p,miR-339-3p,miR-34a-5p,miR-376b-3p,miR-677-5p,and miR-721-were predicted to display gene targets and important signaling pathways closely associated with AD pathogenesis and verified by ddPCR.Conclusions:Urinary exosomal miRNAs showing differences in expression prior to Aβ-plaque deposition were identified.These exosomal miRNAs represent potential noninvasive biomarkers that may be used to prevent AD in clinical applications.

Novel spontaneous myelodysplastic syndrome mouse model

Background:Myelodysplastic syndrome(MDS)is a group of disorders involving he-mopoietic dysfunction leading to leukemia.Although recently progress has been made in identifying underlying genetic mutations,many questions still remain.Animal models of MDS have been produced by introduction of specific mutations.However,there is no spontaneous mouse model of MDS,and an animal model to simulate natu-ral MDS pathogenesis is urgently needed.Methods:In characterizing the genetically diverse mouse strains of the Collaborative Cross(CC)we observed that one,designated JUN,had abnormal hematological traits.This strain was thus further analyzed for phenotypic and pathological iden-tification,comparing the changes in each cell population in peripheral blood and in bone marrow.Results:In a specific-pathogen free environment,mice of the JUN strain are rela-tively thin,with healthy appearance.However,in a conventional environment,they become lethargic,develop wrinkled yellow hair,have loose and light stools,and are prone to infections.We found that the mice were cytopenic,which was due to abnor-mal differentiation of multipotent bone marrow progenitor cells.These are common characteristics of MDS.Conclusions:A mouse strain,JUN,was found displaying spontaneous myelodysplas-tic syndrome.This strain has the advantage over existing models in that it develops MDS spontaneously and is more similar to human MDS than genetically modified mouse models.JUN mice will be an important tool for pathogenesis research of MDS and for evaluation of new drugs and treatments.

Metabolism of minor isoforms of prion proteins Cytosolic prion protein and transmembrane prion protein

Transmissible spongiform encephalopathy or prion disease is triggered by the conversion from cellular prion protein to pathogenic prion protein. Growing evidence has concentrated on prion protein configuration changes and their correlation with prion disease transmissibility and patho- genicity. In vivo and in vitro studies have shown that several cytosolic forms of prion protein with specific topological structure can destroy intracellular stability and contribute to prion protein pathogenicity. In this study, the latest molecular chaperone system associated with endoplasmic re- ticulum-associated protein degradation, the endoplasmic reticulum resident protein quality-control system and the ubiquitination proteasome system, is outlined. The molecular chaperone system directly correlates with the prion protein degradation pathway. Understanding the molecular mechanisms will help provide a fascinating avenue for further investigations on prion disease treatment and prion protein-induced neurodegenerative diseases.

Infection with SARS-CoV-2 can cause pancreatic impairment

Evidence suggests associations between COVID-19 patients or vaccines and glycometabolic dysfunction and an even higher risk of the occurrence of diabetes.Herein,we retrospectively analyzed pancreatic lesions in autopsy tissues from 67 SARS-CoV-2 infected non-human primates(NHPs)models and 121 vaccinated and infected NHPs from 2020 to 2023 and COVID-19 patients.Multi-label immunofluorescence revealed direct infection of both exocrine and endocrine pancreatic cells by the virus in NHPs and humans.Minor and limited phenotypic and histopathological changes were observed in adult models.Systemic proteomics and metabolomics results indicated metabolic disorders,mainly enriched in insulin resistance pathways,in infected adult NHPs,along with elevated fasting C-peptide and C-peptide/glucose ratio levels.Furthermore,in elder COVID-19 NHPs,SARS-CoV-2 infection causes loss of beta(β)cells and lower expressed-insulin in situ characterized by islet amyloidosis and necrosis,activation ofα-SMA and aggravated fibrosis consisting of lower collagen in serum,an increase of pancreatic inflammation and stress markers,ICAM-1 and G3BP1,along with more severe glycometabolic dysfunction.In contrast,vaccination maintained glucose homeostasis by activating insulin receptorαand insulin receptorβ.Overall,the cumulative risk of diabetes post-COVID-19 is closely tied to age,suggesting more attention should be paid to blood sugar management in elderly COVID-19 patients.

SARS-CoV-2 crosses the blood-brain barrier accompanied with basement membrane disruption without tight junctions alteration

SARS-CoV-2 has been reported to show a capacity for invading the brains of humans and model animals.However,it remains undear whether and how SARS-CoV-2 crosses the blood-brain barrier(BBB).Herein,SARS-CoV-2 RNA was occasionally detected in the vascular wall and perivascular space,as well as in brain microvascular endothelial cells(BMECs)in the infected K18-hACE2 transgenic mice.Moreover,the permeability of the infected vessel was in creased.Furthermore,disin tegrity of BBB was discovered in the infected hamsters by administration of Evans blue.Interestingly,the expression of claudin5,ZO-1,occludin and the ultrastructure of tight junctions(TJs)showed unchanged,whereas,the basement membrane was disrupted in the infected animals.Using an in vitro BBB model that comprises primary BMECs with astrocytes,SARS-CoV-2 was found to infect and cross through the BMECs.Consistent with in vivo experiments,the expression of MMP9 was increased and collagen IV was decreased while the markers for TJs were not altered in the SARS-CoV-2-infected BMECs.Besides,inflammatory responses including vasculitis,glial activation,and upregulated inflammatory factors occurred after SARS-CoV-2 infection.Overall,our results provide evidence supporting that SARS-CoV-2 can cross the BBB in a transcellular pathway accompanied with basement membrane disrupted without obvious alteration of TJs.

Sequential infection with H1N1 and SARS-CoV-2 aggravated COVID-19 pathogenesis in a mammalian model, and covaccination as an effective method of prevention of COVID-19 and influenza

Influenza A virus may circulate simultaneously with the SARS-CoV-2 virus,leading to more serious respiratory diseases during this winter.However,the influence of these viruses on disease outcome when both influenza A and SARS-CoV-2 are present in the host remains unclear.Using a mammalian model,sequential infection was performed in ferrets and in K18-MCE2 mice,with SARS-CoV-2 infection following H1N1.We found that co-infection with H1N1 and SARS-CoV-2 extended the duration of clinical manifestation of COVID-19,and enhanced pulmonary damage,but reduced viral shedding of throat swabs and viral loads in the lungs of ferrets.Moreover,mortality was increased in sequentially infected mice compared with single-infection mice.Compared with singlevaccine inoculation,co-inoculation of PiCoVacc(a SARS-CoV-2 vaccine)and the flu vaccine showed no significant differences in neutralizing antibody titers or virus-specific immune responses.Combined immunization effectively protected K18-MCE2 mice against both H1N1 and SARS-CoV-2 infection.Our findings indicated the development of systematic models of co-infection of H1N1 and SARS-CoV-2,which together notably enhanced pneumonia in ferrets and mice,as well as demonstrated that simultaneous vaccination against HINT and SARS-CoV-2 may be an effective prevention strategy for the coming winter.

Integrated histopathological,lipidomic,and metabolomic profiles reveal mink is a useful animal model to mimic the pathogenicity of severe COVID-19 patients

Severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)is transmitted on mink farms between minks and humans in many countries.However,the systemic pathological features of SARS-CoV-2-infected minks are mostly unknown.Here,we demonstrated that minks were largely permissive to SARS-CoV-2,characterized by severe and diffuse alveolar damage,and lasted at least 14 days post inoculation(dpi).We first reported that infected minks displayed multiple organ-system lesions accompanied by an increased inflammatory response and widespread viral distribution in the cardiovascular,hepatobiliary,urinary,endocrine,digestive,and immune systems.The viral protein partially co-localized with activated Mac-2+macrophages throughout the body.Moreover,we first found that the alterations in lipids and metabolites were correlated with the histological lesions in infected minks,especially at 6 dpi,and were similar to that of patients with severe and fatal COVID-19.Particularly,altered metabolic pathways,abnormal digestion,and absorption of vitamins,lipids,cholesterol,steroids,amino acids,and proteins,consistent with hepatic dysfunction,highlight metabolic and immune dysregulation.Enriched kynurenine in infected minks contributed to significant activation of the kynurenine pathway and was related to macrophage activation.Melatonin,which has significant anti-inflammatory and immunomodulating effects,was significantly downregulated at 6 dpi and displayed potential as a targeted medicine.Our data first illustrate systematic analyses of infected minks to recapitulate those observations in severe and fetal COVID-19 patients,delineating a useful animal model to mimic SARS-CoV-2-induced systematic and severe pathophysiological features and provide a reliable tool for the development of effective and targeted treatment strategies,vaccine research,and potential biomarkers.

Sequential immunizations confer cross-protection against variants of SARS-CoV-2,including Omicron in Rhesus macaques

Variants of concern(VOCs)like Delta and Omicron,harbor a high number of mutations,which aid these viruses in escaping a majority of known SARS-CoV-2 neutralizing antibodies(NAbs).In this study,Rhesus macaques immunized with 2-dose inactivated vaccines(Coronavac)were boosted with an additional dose of homologous vaccine or an RBD-subunit vaccine,or a bivalent inactivated vaccine(Beta and Delta)to determine the effectiveness of sequential immunization.The booster vaccination significantly enhanced the duration and levels of neutralizing antibody titers against wild-type.

sRAGE alleviates SARS-CoV-2-induced pneumonia in hamster

Dear Editor Since last year,the most demanding task of the global pharmaceutical community has been focused on the development of strategies to treat coronavirus disease 2019(COVID-19).To date,several vaccines have been developed and already demonstrated their efficacy in reducing the incidence of COVID-19.1 However,the development of drugs treating COVID-19 is lagging far behind,and all the current treatment regimens have their limitations.