K18-hACE2 mice develop respiratory disease resembling severe COVID-19

SARS-CoV-2 emerged in late 2019 and resulted in the ongoing COVID-19 pandemic. Several animal models have been rapidly developed that recapitulate the asymptomatic to moderate disease spectrum. Now, there is a direct need for additional small animal models to study the pathogenesis of severe COVID-19 and for fast-tracked medical countermeasure development. Here, we show that transgenic mice expressing the human SARS-CoV-2 receptor (angiotensin-converting enzyme 2 [hACE2]) under a cytokeratin 18 promoter (K18) are susceptible to SARS-CoV-2 and that infection resulted in a dose-dependent lethal disease course. After inoculation with either 104 TCID50 or 105 TCID50, the SARS-CoV-2 infection resulted in rapid weight loss in both groups and uniform lethality in the 105 TCID50 group. High levels of viral RNA shedding were observed from the upper and lower respiratory tract and intermittent shedding was observed from the intestinal tract. Inoculation with SARS-CoV-2 resulted in upper and lower respiratory tract infection with high infectious virus titers in nasal turbinates, trachea and lungs. The observed interstitial pneumonia and pulmonary pathology, with SARS-CoV-2 replication evident in pneumocytes, were similar to that reported in severe cases of COVID-19. SARS-CoV-2 infection resulted in macrophage and lymphocyte infiltration in the lungs and upregulation of Th1 and proinflammatory cytokines/chemokines. Extrapulmonary replication of SARS-CoV-2 was observed in the cerebral cortex and hippocampus of several animals at 7 DPI but not at 3 DPI. The rapid inflammatory response and observed pathology bears resemblance to COVID-19. Additionally, we demonstrate that a mild disease course can be simulated by low dose infection with 102 TCID50 SARS-CoV-2, resulting in minimal clinical manifestation and near uniform survival. Taken together, these data support future application of this model to studies of pathogenesis and medical countermeasure development.

The levels of caspase-cleaved cytokeratin 18 are elevated in serum from patients with lung cancer and helpful to predict the survival

Caspase-cleaved cytokeratin 18 fragments (M30 antigen) can be detected in the circulation of patients with carcinoma and are believed to reflect cell death of tumors of epithelial origin. M30 antigens cleaved at Asp396 are detected using an epitope-specific antibody (M30 antibody). We here measured the levels of such fragments in patients with lung cancer (n=60), patients with benign lung disease (n=22) and healthy control subjects (n=32). A statistically significant difference was observed between these groups (p<0.001; Kruskal-Wallis). Basal M30 antigen levels were evaluated with regard to their predictive power of survival. The best cut-off value for M30 antigen level for the prediction of death was 43.8 U/L. Patients with basal M30 antigen levels higher than 43.8 U/L had significantly shorter median survival than those with lower basal M30 antigen levels (p=0.013; hazard ratio: 3.9) (95% CI=1.3-11.4). To determine whether cytotoxic therapy increases serum M30 antigen in lung cancer patients, we monitored the levels of M30 antigen in 18 lung cancer patients before chemotherapy and after 24 and 48 h. An approximately four-fold increase in M30 antigen levels was observed at 48 h (p<0.001). These results suggest as a first time that serum M30 antigen might be used as a novel biomarker for prediction of survival as well as for monitoring the efficiency of chemotherapy in lung cancer patients.

Cytokeratin autoantibodies: useful serologic markers for toluene diisocyanate-induced asthma

To evaluate the clinical significance of autoantibodies to three major epithelial cytokeratins (CK)--CK8, CK18, and CK19--we compared 66 patients with toluene diisocyanate (TDI)-induced asthma (group I) with three control groups: 169 asymptomatic exposed subjects (group II), 64 patients with allergic asthma (group III), and 123 unexposed healthy subjects (group IV). Serum IgG, specific for human recombinant CKs, were measured by ELISA (enzyme linked immunosorbent assay), and ELISA inhibition tests were performed. The existence of these antibodies was confirmed by IgG immunoblot analysis. Anti-TDI-HSA (human serum albumin) IgE and IgG antibodies were measured by ELISA in the same set of the patients. The prevalence of CK8, CK18, and CK19 auotantibodies in group I was significantly higher than in the other three groups. Results of the ELISA inhibition test showed significant inhibition with the addition of three CKs in a dose-dependent manner. No significant association was found between CK autoantibodies and the prevalence of anti- TDI-HSA IgG and IgE antibodies. These results suggest that autoantibodies to CK18 and CK19 can be used as serologic markers for identifying patients with TDI-induced asthma among exposed workers.

Method validation and preliminary qualification of pharmacodynamic biomarkers employed to evaluate the clinical efficacy of an antisense compound (AEG35156) targeted to the X-linked inhibitor of apoptosis protein XIAP

Data are presented on pharmacodynamic (PD) method validation and preliminary clinical qualification of three PD biomarker assays. M65 Elisa, which quantitates different forms of circulating cytokeratin 18 (CK18) as putative surrogate markers of both apoptotic and nonapoptotic tumour cell death, was shown to be highly reproducible: calibration curve linearity r2 = 0.996, mean accuracy > 91% and mean precision < 3%, n = 27. Employing recombinant (r) CK18 and caspase cleaved CK18 (CK18 Asp396 neo-epitope) as external standards, kit to kit reproducibly was < 6% (n = 19). rCK18 was stable in plasma for 4 months at -20 degrees C and -80 degrees C, for 4 weeks at 4 degrees C and had a half-life of 2.3 days at 37 degrees C. Cytokeratin 18 Asp396 NE, the M30 Apoptosense Elisa assay antigen, was stable in plasma for 6 months at -20 degrees C and -80 degrees C, for 3 months at 4 degrees C, while its half-life at 37 degrees C was 3.8 days. Within-day variations in endogenous plasma concentrations of the M30 and M65 antigens were assessed in two predose blood samples collected from a cohort of 15 ovarian cancer patients receiving carboplatin chemotherapy and were shown to be no greater than the variability associated with methods themselves. Between-day fluctuations in circulating levels of the M30 and M65 antigens and in XIAP mRNA levels measured in peripheral blood mononuclear cells by quantitative (q) RT-PCR were evaluated in two predose blood samples collected with a 5- to 7-day gap from 23 patients with advanced cancer enrolled in a phase I trial. The mean variation between the two pretreatment values ranged from 13 to 14 to 25%, respectively, for M65, M30 and qRT-PCR. These data suggest that the M30 and M65 Elisa's and qRT-PCR as PD biomarker assays have favourable performance characteristics for further investigation in clinical trials of anticancer agents which induce tumour apoptosis/necrosis or knockdown of the anti-apoptotic protein XIAP.