Ex vivo SARS-CoV-2 infection of human lung reveals heterogeneous host defense and therapeutic responses

Cell lines are the mainstay in understanding the biology of COVID-19 infection but do not recapitulate many of the complexities of human infection. The use of human lung tissue is one solution for the study of such novel respiratory pathogens. We hypothesized that a cryopreserved bank of human lung tissue would allow for the ex vivo study of the interindividual heterogeneity of host response to SARS-CoV-2, thus providing a bridge between studies with cell lines and studies in animal models. We generated a cryobank of tissues from 21 donors, many of whom had clinical risk factors for severe COVID-19. Cryopreserved tissues preserved 90% cell viability and contained heterogenous populations of metabolically active epithelial, endothelial, and immune cell subsets of the human lung. Samples were readily infected with HCoV-OC43 and SARS-CoV-2 and demonstrated comparable susceptibility to infection. In contrast, we observed a marked donor-dependent heterogeneity in the expression of IL6, CXCL8, and IFNB1 in response to SARS-CoV-2. Treatment of tissues with dexamethasone and the experimental drug N-hydroxycytidine suppressed viral growth in all samples, whereas chloroquine and remdesivir had no detectable effect. Metformin and sirolimus, molecules with predicted but unproven antiviral activity, each suppressed viral replication in tissues from a subset of donors. In summary, we developed a system for the ex vivo study of human SARS-CoV-2 infection using primary human lung tissue from a library of donor tissues. This model may be useful for drug screening and for understanding basic mechanisms of COVID-19 pathogenesis.

Total immunoreactive alpha-inhibin in human seminal plasma, sperm quality, and in vitro fertilization rates

OBJECTIVE

To assess the relationship between the concentrations of total immunoreactive alpha-inhibin in human seminal plasma, sperm quality, and in vitro fertilization (IVF) rates.

SETTING

Medical school hospital.

DESIGN

Prospective study.

PATIENTS

72 consecutive couples undergoing IVF with husband's sperm in which at least 4 oocytes were obtained.

MAIN OUTCOME MEASURES

Alpha-inhibin determination by means of enzyme-linked immunosorbent assay, sperm analysis for density and motility, IVF rates.

RESULTS

Total immunoreactive alpha-inhibin levels were not correlated with IVF rates. Nor were there any differences in fertilization rates in the different groups. Lower inhibin levels were found in oligozoospermic cases. Lower sperm counts were found in cases with inhibin values below the median value, and also with respect to various other cutoffs. No correlation was found between inhibin levels and any of the sperm variables measured.

CONCLUSION

Total immunoreactive alpha-inhibin is not a prognostic factor in IVF cycles. However, an association was found between inhibin and sperm concentration, suggesting that alpha-inhibin in the human seminal fluid could be a marker for some aspects of spermatogenesis.