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Background Key knowledge gaps remain in the understanding of viral dynamics and immune response of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection. Methods We evaluated these characteristics and established their association with clinical severity in a prospective observational cohort study of 100 patients with PCR-confirmed SARS-CoV-2 infection (mean age, 46 years; 56% male; 38% with comorbidities). Respiratory samples (n = 74) were collected for viral culture, serum samples for measurement of IgM/IgG levels (n = 30), and plasma samples for levels of inflammatory cytokines and chemokines (n = 81). Disease severity was correlated with results from viral culture, serologic testing, and immune markers. Results Fifty-seven (57%) patients developed viral pneumonia, of whom 20 (20%) required supplemental oxygen, including 12 (12%) with invasive mechanical ventilation. Viral culture from respiratory samples was positive for 19 of 74 patients (26%). No virus was isolated when the PCR cycle threshold (Ct) value was >30 or >14 days after symptom onset. Seroconversion occurred at a median (IQR) of 12.5 (9–18) days for IgM and 15.0 (12–20) days for IgG; 54/62 patients (87.1%) sampled at day 14 or later seroconverted. Severe infections were associated with earlier seroconversion and higher peak IgM and IgG levels. Levels of IP-10, HGF, IL-6, MCP-1, MIP-1α, IL-12p70, IL-18, VEGF-A, PDGF-BB, and IL-1RA significantly correlated with disease severity. Conclusions We found virus viability was associated with lower PCR Ct value in early illness. A stronger antibody response was associated with disease severity. The overactive proinflammatory immune signatures offer targets for host-directed immunotherapy, which should be evaluated in randomized controlled trials.

Reactivation of latent human cytomegalovirus (HCMV) infection following transplantation is associated with high morbidity and mortality. In vivo, myeloid cells and their progenitors are an important site of HCMV latency, whose establishment and/or maintenance requires expression of UL138. Using SILAC (stable isotope labeling by amino acids in cell culture)-based mass spectrometry, we found a dramatic UL138-mediated loss of cell surface Multidrug Resistanceassociated Protein-1 (MRP1), and reduction of substrate export by this transporter. Latencyassociated loss of MRP1 and accumulation of the cytotoxic drug vincristine, an MRP1 substrate, depleted virus from naturally latent CD14 + and CD34 + progenitors, all in vivo sites of latency. The UL138-mediated loss of MRP1 provides a marker for detecting latent HCMV infection and a therapeutic target for eliminating latently-infected cells prior to transplantation.

ObjectiveAs the current therapeutic strategies for human hepatocellular carcinoma (HCC) have been proven to have limited effectiveness, immunotherapy becomes a compelling way to tackle the disease. We aim to provide humanised mouse (humice) models for the understanding of the interaction between human cancer and immune system, particularly for human-specific drug testing.DesignPatient-derived xenograft tumours are established with type I human leucocyte antigen matched human immune system in NOD-scid Il2rg−/− (NSG) mice. The longitudinal changes of the tumour and immune responses as well as the efficacy of immune checkpoint inhibitors are investigated.ResultsSimilar to the clinical outcomes, the human immune system in our model is educated by the tumour and exhibits exhaustion phenotypes such as a significant declination of leucocyte numbers, upregulation of exhaustion markers and decreased the production of human proinflammatory cytokines. Notably, cytotoxic immune cells decreased more rapidly compared with other cell types. Tumour infiltrated T cells have much higher expression of exhaustion markers and lower cytokine production compared with peripheral T cells. In addition, tumour-associated macrophages and myeloid-derived suppressor cells are found to be highly enriched in the tumour microenvironment. Interestingly, the tumour also changes gene expression profiles in response to immune responses by upregulating immune checkpoint ligands. Most importantly, in contrast to the NSG model, our model demonstrates both therapeutic and side effects of immune checkpoint inhibitors pembrolizumab and ipilimumab.ConclusionsOur work provides a model for immune-oncology study and a useful parallel-to-human platform for anti-HCC drug testing, especially immunotherapy.

There are considerable challenges in directly targeting the mutant p53 protein, given the large heterogeneity of p53 mutations in the clinic. An alternative approach is to exploit the altered fitness of cells imposed by loss-of-wild-type p53. Here we identify niclosamide through a HTS screen for compounds selectively killing p53-deficient cells. Niclosamide impairs the growth of p53-deficient cells and of p53 mutant patient-derived ovarian xenografts. Metabolome profiling reveals that niclosamide induces mitochondrial uncoupling, which renders mutant p53 cells susceptible to mitochondrial-dependent apoptosis through preferential accumulation of arachidonic acid (AA), and represents a first-in-class inhibitor of p53 mutant tumors. Wild-type p53 evades the cytotoxicity by promoting the transcriptional induction of two key lipid oxygenation genes, ALOX5 and ALOX12B, which catalyzes the dioxygenation and breakdown of AA. Therefore, we propose a new paradigm for targeting cancers defective in the p53 pathway, by exploiting their vulnerability to niclosamide-induced mitochondrial uncoupling.

Non-alcoholic fatty liver disease (NAFLD) has been on a global rise. While animal models have rendered valuable insights to the pathogenesis of NAFLD, discrepancy with patient data still exists. Since non-alcoholic steatohepatitis (NASH) involves chronic inflammation, and CD4 + T cell infiltration of the liver is characteristic of NASH patients, we established and characterized a humanized mouse model to identify humanspecific immune response(s) associated with NAFLD progression. Immunodeficient mice engrafted with human immune cells (HIL mice) were fed with high fat and high calorie (HFHC) or chow diet for 20 weeks. Liver histology and immune profile of HIL mice were analyzed and compared with patient data. HIL mice on HFHC diet developed steatosis, inflammation and fibrosis of the liver. Human CD4 + central and effector memory T cells increased within the liver and in the peripheral blood of our HIL mice, accompanied by marked up-regulation of pro-inflammatory cytokines (IL-17A and IFNγ). In vivo depletion of human CD4 + T cells in HIL mice reduced liver inflammation and fibrosis, but not steatosis. Our results highlight CD4 + memory T cell subsets as important drivers of NAFLD progression from steatosis to fibrosis and provides a humanized mouse model for pre-clinical evaluation of potential therapeutics.

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ObjectiveHCV infection affects millions of people worldwide, and many patients develop chronic infection leading to liver cancers. For decades, the lack of a small animal model that can recapitulate HCV infection, its immunopathogenesis and disease progression has impeded the development of an effective vaccine and therapeutics. We aim to provide a humanised mouse model for the understanding of HCV-specific human immune responses and HCV-associated disease pathologies.DesignRecently, we have established human liver cells with a matched human immune system in NOD-scid Il2rg−/− (NSG) mice (HIL mice). These mice are infected with HCV by intravenous injection, and the pathologies are investigated.ResultsIn this study, we demonstrate that HIL mouse is capable of supporting HCV infection and can present some of the clinical symptoms found in HCV-infected patients including hepatitis, robust virus-specific human immune cell and cytokine responses as well as liver fibrosis and cirrhosis. Similar to results obtained from the analysis of patient samples, the human immune cells, particularly T cells and macrophages, play critical roles during the HCV-associated liver disease development in the HIL mice. Furthermore, our model is demonstrated to be able to reproduce the therapeutic effects of human interferon alpha 2a antiviral treatment.ConclusionsThe HIL mouse provides a model for the understanding of HCV-specific human immune responses and HCV-associated disease pathologies. It could also serve as a platform for antifibrosis and immune-modulatory drug testing.