A new mouse unilateral model of diffuse alveolar damage of the lung.

OBJECTIVE AND DESIGN: The existing biological models of diffuse alveolar damage (DAD) in mice have many shortcomings. To offset these shortcomings, we have proposed a simple, nonsurgical, and reproducible method of unilateral total damage of the left lung in ICR mice. This model is based on the intrabronchial administration of a mixture of bacterial lipopolysaccharide (LPS) from the cell wall of S. enterica and α-galactosylceramide (inducing substances) to the left lung. METHODS: Using computer tomography of the lungs with endobronchial administration of contrast material, we have been able to perform an operative intravital verification of the targeted delivery of the inducer. The model presented is characterized by more serious and homogeneous damage of the affected lung compared to the existing models of focal pneumonia; at the same time, our model is characterized by longer animal survival since the right lung remains intact. RESULTS: The model is also characterized by diffuse alveolar damage of the left lung, animal survival of 100%, abrupt increases in plasma levels of TNFa, INFg, and IL-6, and significant myocardial overload in the right heart. It can be used to assess the efficacy of innovative drugs for the treatment of DAD and ARDS as the clinical manifestations that are developed in patients infected with SARS-CoV-2. Morphological patterns of lungs in the noninfectious ("sterile") model of DAD induced by LPS simultaneously with α-galactosylceramide (presented here) and in the infectious model of DAD induced by SARS-CoV-2 have been compared. CONCLUSION: The DAD model we have proposed can be widely used for studying the efficacy of candidate molecules for the treatment of infectious respiratory diseases, such as viral pneumonias of different etiology, including SARS-CoV-2.

Resistance to tumor necrosis factor induced apoptosis in vitro correlates with high metastatic capacity of cells in vivo.

TNF is one of the cytokines secreted by the cells of the immune system. Our data demonstrate that those cell lines lacking capability to form metastatic tumors in vivo are susceptible to TNF induced apoptosis in vitro. However, cell lines with high metastatic potential are resistant to TNF in vitro. Furthermore, the same cell lines were resistant to cytolytic action of other cytotoxic proteins secreted by LAK cells. Our data showed that TNF resistance in vitro correlates with the increased level of transcription factor NF-kappaB. This finding may provide a tool to improve current protocols of immunotherapy and insights to how tumor cells are or are not killed by LAK cells.

Inhibitory effect of calf fetuin on the cytotoxic activity of LAK cell-derived factors and tumor necrosis factor.

A protein-inhibiting LAK cell-mediated cytotoxicity was isolated from a LAK cell-conditioned medium. The N-terminal amino acid sequence of this protein appeared to be identical to fetal calf fetuin. Pure isolated fetuin, as well as commercially available preparations of this protein, were shown to inhibit cytotoxic activity of both cytotoxic proteins released by LAK cells and TNF.

Contribution of membrane-associated cytotoxic proteins to cytolysis of L929 and K562 target cells mediated by LAK cells with different phenotypes.

We have demonstrated that the relative contribution of secreted and membrane-associated proteins to the cytotoxicity of LAK cells depended on LAK cell phenotype: the cytotoxicity of CD16+ CD8+ CD3- LAK cells was associated mainly with membrane-bound proteins, and the activity of CD3+ CD8+ CD16- LAK cells was due mainly to secreted soluble proteins. The cytotoxic activity of membrane fractions of LAK cells against cell line L929 was determined by 40-, 32- and 21-kDa proteins for LAK cells bearing NK-specific markers and due to proteins of 34 and 21 kDa in the case of 'CTL-like' LAK-cells.