Yanfeng Xu

An Animal Model of MERS Produced by Infection of Rhesus Macaques With MERS Coronavirus

Abstract In 2012, a novel coronavirus (CoV) associated with severe respiratory disease, Middle East respiratory syndrome (MERS-CoV; previously known as human coronavirus–Erasmus Medical Center or hCoV-EMC), emerged in the Arabian Peninsula. To date, 114 human cases of MERS-CoV have been reported, with 54 fatalities. Animal models for MERS-CoV infection of humans are needed to elucidate MERS pathogenesis and to develop vaccines and antivirals. In this study, we developed rhesus macaques as a model for MERS-CoV using intratracheal inoculation. The infected monkeys showed clinical signs of disease, virus replication, histological lesions, and neutralizing antibody production, indicating that this monkey model is suitable for studies of MERS-CoV infection.

miR-29c regulates BACE1 protein expression.

Recently, BACE1 expression was shown to be regulated by microRNAs, small endogenous RNA molecules that regulate protein expression through sequence-specific interaction with messenger RNA. Here, we showed that microRNA-29c (miR-29c), a miRNA that is enriched in the brain and highly expressed in the APPswe/PSΔE9 mouse lowers BACE1 protein in vitro and in transgenic miR-29c mice. In silico analysis identified two putative target sites in the BACE1 mRNA for the miR-29c family. We chose SH-SY5Y, HEK-293T cell lines and miR-29c transgenic mice for these studies to validate our hypothesis. Significantly, over-expression of miR-29c in SH-SY5Y, HEK-293T cell lines and miR-29c transgenic mice downregulated BACE1 protein levels. Our findings suggest that miR-29c may be an endogenous regulator of BACE1 protein expression.

Novel Avian-Origin Human Influenza A(H7N9) Can Be Transmitted Between Ferrets via Respiratory Droplets

The outbreak of human infections caused by novel avian-origin influenza A(H7N9) in China since March 2013 underscores the need to better understand the pathogenicity and transmissibility of these viruses in mammals. In a ferret model, the pathogenicity of influenza A(H7N9) was found to be less than that of an influenza A(H5N1) strain but comparable to that of 2009 pandemic influenza A(H1N1), based on the clinical signs, mortality, virus dissemination, and results of histopathologic analyses. Influenza A(H7N9) could replicate in the upper and lower respiratory tract, the heart, the liver, and the olfactory bulb. It is worth noting that influenza A(H7N9) exhibited a low level of transmission between ferrets via respiratory droplets. There were 4 mutations in the virus isolated from the contact ferret: D678Y in the gene encoding PB2, R157K in the gene encoding hemagglutinin (H3 numbering), I109T in the gene encoding nucleoprotein, and T10I in the gene encoding neuraminidase. These data emphasized that avian-origin influenza A(H7N9) can be transmitted between mammals, highlighting its potential for human-to-human transmissibility.

Human mesenchymal stem cell transplantation protects against cerebral ischemic injury and upregulates interleukin-10 expression in Macacafascicularis

Mesenchymal stem cell (MSC) transplantation has been reported to improve neurologic function after ischemic injury. However, the detailed mechanisms by which MSCs promote functional recovery are not fully understood. Interleukin-10 (IL-10) is a well-known anti-inflammatory cytokine with neuroprotective effects with respect to brain injury. In this study, a non-human primate ischemia model was used to test the hypothesis that transplanted human bone-marrow-derived MSCs (hBMSCs) exert a neuroprotective effects on cerebral ischemia and upregulate IL-10 expression. We also assessed neuronal apoptosis and astroglial activity in the area around the ischemic lesion and proliferating cells in the subventricular zone (SVZ). Results showed that hBMSC transplantation in ischemic tissues improved the neurological functions and induced an increase in IL-10 expression. In addition, neuronal apoptosis and astroglial activity in the peri-ischemic area decreased, and the number of proliferating cells in the SVZ increased. These results provide a novel therapeutic strategy for improving neurologic function after cerebral ischemia.

Tubastatin A/ACY-1215 improves cognition in Alzheimer's disease transgenic mice.

Histone deacetylase 6 (HDAC6) is currently being discussed as a promising therapeutic target for the treatment of Alzheimers disease (AD). Mounting evidence indicates that increased HDAC6 expression may contribute to AD-associated neurodegeneration, although beneficial effects have also been identified. In the present study, we tested the potential of two selective HDAC6 inhibitors, tubastatin A and ACY-1215, to rescue cognitive deficits in a mouse model of AD. We found that both tubastatin A and ACY-1215 alleviated behavioral deficits, altered amyloid-β (Aβ) load, and reduced tau hyperphosphorylation in AD mice without obvious adverse effects. Our data suggested that tubastatin A and ACY-1215 not only promoted tubulin acetylation, but also reduced production and facilitated autophagic clearance of Aβ and hyperphosphorylated tau. Further, the decreased hyperphosphorylated tau and increased tubulin acetylation may account for the improved microtubule stability in AD mice after tubastatin A/ACY-1215 treatment. These preclinical results support the detrimental role of HDAC6 in AD, and offer prospective approaches for using tubastatin A/ACY-1215 as potential therapeutic strategy for AD.

Lycorine reduces mortality of human enterovirus 71-infected mice by inhibiting virus replication

Human enterovirus 71 (EV71) infection causes hand, foot and mouth disease in children under 6 years old and this infection occasionally induces severe neurological complications. No vaccines or drugs are clinical available to control EV71 epidemics. In present study, we show that treatment with lycorine reduced the viral cytopathic effect (CPE) on rhabdomyosarcoma (RD) cells by inhibiting virus replication. Analysis of this inhibitory effect of lycorine on viral proteins synthesis suggests that lycorine blocks the elongation of the viral polyprotein during translation. Lycorine treatment of mice challenged with a lethal dose of EV71 resulted in reduction of mortality, clinical scores and pathological changes in the muscles of mice, which were achieved through inhibition of viral replication. When mice were infected with a moderate dose of EV71, lycorine treatment was able to protect them from paralysis. Lycorine may be a potential drug candidate for the clinical treatment of EV71-infected patients.

Histopathological features and distribution of EV71 antigens and SCARB2 in human fatal cases and a mouse model of enterovirus 71 infection

Enterovirus 71 (EV71) is a neurotropic pathogen that causes hand, foot, and mouth disease. While infection is usually self-limiting, a minority of patients infected with EV71 develop severe neurological complications. In humans, EV71 has been reported to utilize the scavenger receptor class B, member 2 (SCARB2) as a receptor for infectious cellular entry. In this study, we define the pathological features of EV71-associated disease as well as the distribution of EV71 antigen and SCARB2 in human fatal cases and a mouse model. Histopathologically, human fatal cases showed severe central nervous system (CNS) changes, mainly in the brainstems, spinal cords, and thalamus. These patient further exhibited pulmonary edema and necrotic enteritis. Immunohistochemical analysis of human fatal cases demonstrated that EV71 antigen and SCARB2 were observed mainly in neurons, microglia cells and inflammatory cells in the CNS, and epithelial cells in the intestines. However, skeletal muscle tissue was negative for EV71 antigen. In a mouse model of EV71 infection, we observed massive necrotic myositis, different degrees of viral diseases in CNS, and extensive interstitial pneumonia. In mice, EV71 exhibits strong myotropism compared to the neurotropism seen in humans. EV71 antigen was detected in the spinal cord and brainstem of mice. However, there was no clear correlation between mouse SCARB2 and EV71 antigen distribution in the mouse model, consistent with previous results that SCARB2 functions as a receptor for EV71 in humans but not mice. The EV71-induced lesions seen in the mouse model resembled the pathological changes seen in human samples. These results increase our understanding of EV71 pathogenesis and will inform further work developing a mouse model for EV71 infection.

G-protein-coupled receptor kinase 5, overexpressed in the α-synuclein up-regulation model of Parkinson's disease, regulates bcl-2 expression

G protein-coupled receptor kinase 5 (GRK5) has been reported to accumulate in Lewy bodies (LBs), a histological hallmark of Parkinsons disease. Recent findings propose that GRK5 might function in Parkinsons disease via phosphorylation of alpha-synuclein, a major component of LBs. In this study, the changes of the expression levels of GRK5 and its possible effects in Parkinsons disease were evaluated in cell lines and transgenic mice model of alpha-synuclein overexpression. Both the expression levels of cytoplasmic and nuclear distributed GRK5 were induced an increase via alpha-synuclein overexpression in vivo and in vitro. The observations that the levels of alpha-synuclein phosphorylated at Ser-129 (pS129-alpha-synuclein) remain unchanged despite the downregulation of GRK5 by short hairpin ribonucleic acid (shRNA) transfection suggest that GRK5 is not the sole kinase involved in phosphorylating alpha-synuclein in Parkinsons disease. In addition, the findings that nuclear accumulation of GRK5 inhibits bcl-2 transcription and expression, at least in part by enhancing histone deacetylase (HDAC) activity, show an unexpected role for nuclear GRK5 in the regulation of an apoptosis-related gene. The present study suggests that GRK5 may be extensively involved in the mechanism of Parkinsons disease.

The mouse and ferret models for studying the novel avian-origin human influenza A (H7N9) virus

BackgroundThe current study was conducted to establish animal models (including mouse and ferret) for the novel avian-origin H7N9 influenza virus.FindingsA/Anhui/1/2013 (H7N9) virus was administered by intranasal instillation to groups of mice and ferrets, and animals developed typical clinical signs including body weight loss (mice and ferrets), ruffled fur (mice), sneezing (ferrets), and death (mice). Peak virus shedding from respiratory tract was observed on 2 days post inoculation (d.p.i.) for mice and 3–5 d.p.i. for ferrets. Virus could also be detected in brain, liver, spleen, kidney, and intestine from inoculated mice, and in heart, liver, and olfactory bulb from inoculated ferrets. The inoculation of H7N9 could elicit seroconversion titers up to 1280 in ferrets and 160 in mice. Leukopenia, significantly reduced lymphocytes but increased neutrophils were also observed in mouse and ferret models.ConclusionsThe mouse and ferret model enables detailed studies of the pathogenesis of this illness and lay the foundation for drug or vaccine evaluation.

Chebulagic acid, a hydrolyzable tannin, exhibited antiviral activity in vitro and in vivo against human enterovirus 71.

Human enterovirus 71 is one of the major causative agents of hand, foot and mouth disease in children under six years of age. Presently, no vaccines or antiviral drugs have been clinically available to employ against EV71. In this study, we demonstrate that treatment with chebulagic acid reduced the viral cytopathic effect on rhabdomyosarcoma cells with an IC50 of 12.5 μg/mL. The utilization of the chebulagic acid treatment on mice challenged with a lethal dose of enterovirus 71 was able to efficiently reduce mortality and relieve clinical symptoms through the inhibition of viral replication. Chebulagic acid may represent a potential therapeutic agent to control infections to enterovirus 71.