Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is the cause of novel coronavirus disease 2019 (COVID-19), was first reported in Wuhan, China, and now has spread across the world as a global pandemic. The propagation from asymptomatic polymerase chain reaction (PCR)-positive individuals represents a complicating factor in the efforts to control the COVID-19 pandemic. We examined the course of PCR assays and the duration of viral shedding in 23 asymptomatic or mild COVID-19 patients from the cruise ship who were admitted to our hospital. Among these 23 cases, the median duration of viral shedding was 19 days (range, 6-37 days) from initial viral detection. Eight cases (35%) had another positive PCR result after testing negative once. Although the duration of viral shedding was approximately three weeks, the infectivity and transmissibility period from asymptomatic and mild COVID-19 cases is unclear. Further studies are needed to determine how long such asymptomatic and mild COVID-19 cases have infectivity.

Hyaluronan (HA)-binding protein involved in HA depolymerization (HYBID), also called cell migration-inducing protein (CEMIP; alias KIAA1199), plays a key role in the degradation of HA in skin and arthritic synovial fibroblasts, but its functions in osteoarthritic (OA) cartilage remain elusive. Here, we investigated the expression and roles of HYBID in human OA cartilage. HYBID was highly expressed by chondrocytes in the HA-depleted area of OA cartilage, and HYBID immunoreactivity was correlated with Mankin score, the histopathologic severity of OA lesions of cartilage. Real-time quantitative PCR indicated that HYBID expression was significantly higher in OA cartilage than in control cartilage. In addition, OA chondrocytes exhibited HA-degrading activity, which was abolished by knock-down of HYBID by siRNAs. Although OA chondrocytes also expressed certain levels of hyaluronidases 1 and 2 and CD44, knock-down of these molecules exhibited negligible effects on HA degradation. Double immunostaining of HYBID and clathrin heavy chain revealed that HYBID was localized in the clathrin-coated vesicles, and HA was endocytosed within the vesicles of OA chondrocytes. Among eight factors including cytokines and growth factors examined, only tumor necrosis factor α stimulated OA chondrocytes to overexpress HYBID. These data are the first to demonstrate that HYBID is up-regulated in OA cartilage, and suggest that tumor necrosis factor α-stimulated HYBID plays a role in HA degradation in OA cartilage.

Cancer cells contain a small population of cancer stem cells or cancer initiating cells, which can be enriched in the side population (SP) after fluorescence activated cell sorting. To examine the members of the ADAM, ADAMTS and MMP gene families related to phenotypes of the SP and the main population (MP), we screened the expression of all the members in the propagated SP and MP of A549 lung adenocarcinoma cells, and found that the relative expression ratio of ADAM23 in the MP to the SP is most highly increased, but none of them are increased in the SP. A similar result on the ADAM23 expression was obtained with another cell line, Calu‐3 cells. Overexpression of ADAM23 inhibited colony formation, cell adhesion and migration, and knockdown of ADAM23 by shRNA showed the reverse effects. ADAM23‐mediated suppression of colony formation, cell adhesion and migration was greatly reduced by treatment with neutralizing anti‐ADAM23 antibody, anti‐αvβ3 integrin antibody and/or ADAM23 disintegrin peptide. Expression of cancer stem cell‐related genes, including AKRC1/2, TM4SF1 and NR0B1, was increased by knockdown of ADAM23. In addition, lung metastasis of A549 transfectants with different levels of ADAM23 expression was negatively regulated by the ADAM23 expression levels. Our data provide evidence that ADAM23 plays a role in suppression of cancer cell progression through interaction with αvβ3 integrin, and suggest that downregulation of ADAM23 in SP cells may contribute toward providing a cancer stem cell phenotype by facilitating the activity of integrin αvβ3.

KeywordsADAM28; C1q; cell death; human normal tissue; mRNA and protein expression

ADAM28 (a disintegrin and metalloproteinase 28) is overexpressed by carcinoma cells in non-small cell lung carcinomas (NSCLC) and plays an important role in cancer cell proliferation and metastasis by reactivation of insulin-like growth factor-1 (IGF-1) and escaping from von Willebrand factor (VWF)-induced apoptosis through digestion of IGF-binding protein-3 and VWF, respectively. To aim for new target therapy of NSCLC patients, we developed human neutralizing antibodies 211-12 and 211-14 against ADAM28, which showed IC values of 62.4 and 37.5 nmol/L, respectively. Antibody 211-14 recognized the junctional region between cysteine-rich domain and secreted-specific domain and showed a K value of 94.7 pmol/L for the epitope-containing peptide. This antibody detected monkey and human secreted-form ADAM28s, although it was not reactive with mouse membrane-anchored ADAM28m. Antibody 211-14 effectively inhibited IGF-1-stimulated cell proliferation of lung adenocarcinoma cell lines with ADAM28 expression, including PC-9 cells, and promoted VWF-induced cell death in these cell lines. In lung metastasis models, antibody 211-14 significantly reduced tumor growth and metastases of PC-9 cells and prolonged survivals in the antibody-treated mice compared with the control IgG-treated ones. Combination therapy of the antibody and docetaxel was more effective than that of bevacizumab and docetaxel and showed further elongation of survival time compared with monotherapy. No adverse effects were observed even after administration of 10-fold more than effective dose of anti-ADAM28 antibody to normal mice. Our data demonstrate that antibody 211-14 is a neutralizing antibody specific to ADAM28s and suggest that this antibody may be a useful treatment remedy for NSCLC patients. .