Hua Zhu

There is mounting scientific evidence indicating a robust association between gut microbiota and nonalcoholic fatty liver disease (NAFLD). Exposure to commensal microbiota in germ-free mice has a significant impact on the regulatory mechanisms of gut genes, in contrast to those conventionally raised. In this study, we have successfully inoculated the gut microbiota from healthy individuals and NAFLD patients into germ-free mice, with the objective of developing a humanized mouse model that accurately replicates the gut microenvironment of NAFLD patients. Changes in blood composition and liver pathology in these mice were systematically measured. Furthermore, we have conducted a detailed analysis of the variations in fecal microbiota and differential metabolites in the blood composition. Our findings indicate a high degree of similarity in disease characteristics between mice colonized with microbiota and humans suffering from NAFLD. Notably, we have observed a strong correlation between alterations in serum differential metabolites and gut microbiota in these mice. KEY MESSAGES: A humanized NFALD mouse model was established based on sterile mice. In microbiota-colonized mice and humans with NAFLD, disease characteristics showed a high degree of similarity. There was a strong association between changes in serum differential metabolites and gut microbiota in mice colonized by intestinal microbiota.

There is mounting scientific evidence indicating a robust association between gut microbiota and nonalcoholic fatty liver disease (NAFLD). Exposure to commensal microbiota in germ-free mice has a significant impact on the regulatory mechanisms of gut genes, in contrast to those conventionally raised. In this study, we have successfully inoculated the gut microbiota from healthy individuals and NAFLD patients into germ-free mice, with the objective of developing a humanized mouse model that accurately replicates the gut microenvironment of NAFLD patients. Changes in blood composition and liver pathology in these mice were systematically measured. Furthermore, we have conducted a det ailed analysis of the variations in fecal microbiota and differential metabolites in the blood composition. Our findings indicate a high degree of similarity in disease characteristics between mice colonized with microbiota and humans suffering from NAFLD. Notably, we have observed a strong correlation between alterations in serum differential metabolites and gut microbiota in these mice.

A recombinant adenovirus vaccine against the SARS Coronavirus (SARS-CoV) was constructed, which contains fragments from the S, N, and Orf8 genes. Rhesus Macaques immunized with the recombinant adenovirus generated antigen-specific humoral and cellular response. Furthermore, the vaccine provided significant protection against subsequent live SARS-CoV challenge. In contrast, three out of four monkeys immunized with placebo suffered severe alveolar damage and pulmonary destruction.

The developmentally regulated brain protein drebrin (Dbn) is a functional protein involved with long-term memory formation and is widely distributed in brain neurons, especially in the dendritic spines. A noticeable decline of this protein has been found in the hippocampus and cortex of patients with Alzheimer’s disease (AD), yet the relationship between Dbn and AD has not been fully understood. In the present study, we examined how down-regulation of Dbn impacts the progression of AD in experimental animals. Accordingly, we injected Dbn interference vector (rAAV-mDbn1 ShRNA) into the hippocampus of three-month old APP(swe)/PS1(ΔE9) mice (APP/PS1 mice) and then successfully down-regulated Dbn expression in this brain region. Behavioral tests, including the Morris water maze test, the open field test, and the novel object test were conducted when the animals were nine months old. Subsequently, MicroPET/CT imaging to monitor glucose metabolism was done. We then investigated Aβ, GFAP, PSD-95, MAP2, vimentin, Cox43, and Syn1 expressions in the brain of the experimental animals via immunohistochemical or immunofluorescence methods. We found that AD mice with a low expression of Dbn performed poorly in the behavioral tests and showed decreased glucose utilization. In the brains of these animals, we detected a slight increase of Aβ, GFAP and vimentin and a significant decline of PSD-95. Altogether our data warrant further studies to elucidate the effect of Dbn on the development and progression of AD.

Alzheimer’s disease (AD) is a leading cause of dementia worldwide, associated with cognitive deficits and brain glucose metabolic alteration. However, the associations of glucose metabolic changes with cognitive dysfunction are less detailed. Here, we examined the brains of APP/presenilin 1 (PS1) transgenic (Tg) mice aged 2, 3.5, 5 and 8 months using ¹⁸F-labed fluorodeoxyglucose (¹⁸F-FDG) microPET to assess age- and brain region-specific changes of glucose metabolism. FDG uptake was calculated as a relative standardized uptake value (SUVr). Morris water maze (MWM) was used to evaluate learning and memory dysfunction. We showed a glucose utilization increase in multiple brain regions of Tg mice at 2 and 3.5 months but not at 5 and 8 months. Comparisons of SUVrs within brains showed higher glucose utilization than controls in the entorhinal cortex, hippocampus, and frontal cortex of Tg mice at 2 and 3.5 months but in the thalamus and striatum at 3.5, 5 and 8 months. By comparing SUVrs in the entorhinal cortex and hippocampus, Tg mice were distinguished from controls at 2 and 3.5 months. In MWM, Tg mice aged 2 months shared a similar performance to the controls (prodromal-AD). By contrast, Tg mice failed training tests at 3.5 months but failed all MWM tests at 5 and 8 months, suggestive of partial or complete cognitive deficits (symptomatic-AD). Correlation analyses showed that hippocampal SUVrs were significantly correlated with MWM parameters in the symptomatic-AD stage. These data suggest that glucose metabolic disorder occurs before onset of AD signs in APP/PS1 mice with the entorhinal cortex and hippocampus affected first, and that regional FDG uptake increase can be an early biomarker for AD. Furthermore, hippocampal FDG uptake is a possible indicator for progression of Alzheimer’s cognition after cognitive decline, at least in animals.

On 19 February 2013, the first patient infected with a novel influenza A H7N9 virus from an avian source showed symptoms of sickness. More than 349 laboratory-confirmed cases and 109 deaths have been reported in mainland China since then. Laboratory-confirmed, human-to-human H7N9 virus transmission has not been documented between individuals having close contact; however, this transmission route could not be excluded for three families. To control the spread of the avian influenza H7N9 virus, we must better understand its pathogenesis, transmissibility, and transmission routes in mammals. Studies have shown that this particular virus is transmitted by aerosols among ferrets. To study potential transmission routes in animals with direct or close contact to other animals, we investigated these factors in a murine model. Viable H7N9 avian influenza virus was detected in the upper and lower respiratory tracts, intestine, and brain of model mice. The virus was transmissible between mice in close contact, with a higher concentration of virus found in pharyngeal and ocular secretions, and feces. All these biological materials were contagious for naïve mice. Our results suggest that the possible transmission routes for the H7N9 influenza virus were through mucosal secretions and feces.

Background: The novel pandemic A (H1N1) virus was first identified in Mexico in April 2009 and since then it spread world wide over a short period of time. Although the virus infection is generally associated with mild disease and a relatively low mortality, it is projected that mutations in specific regions of the viral genome, especially within the receptor binding domain of the hemagglutinin (HA) protein could result in more virulent virus stains, leading to a more severe pandemic. Results: Here, we found that a single amino acid substitution of Asp-to-Gly at position 222 in the HA protein of the A (H1N1) virus occurred after two passage propagation in the allantoic cavities of chicken embryonated eggs, and this single residue variation dramatically increased the viral replication ability in MDCK cells and pathogenicity in BALB/c mice. Conclusions: A substitution of Asp-to-Gly at position 222 in the HA protein was prone to occur under positive selection pressures, and this single amino acid mutation could dramatically increase the virus replication ability in vitro and pathogenicity in vivo. Our finding offers a better understanding of the transmission and evolution of the 2009 pandemic A (H1N1) virus and brings attention to further potentially severe influenza pandemic that may result from cross-host evolution of the influenza viruses.