Galectin-9 protects humanized-ACE2 immunocompetent mice from SARS-CoV-2 Infection

Abstract

Abstract The COVID19 pandemic caused by SARS CoV 2 remains a global health crisis even with vaccines and sparse FDA approved therapies. To limit mortality and morbidity, therapeutics are critical. Galectin 9 (gal9) is a b-galactoside binding protein, modulating cell-cell and cell-matrix interactions. It has been shown circulating gal9 levels are elevated in response to infection in patient sera with moderate to severe disease. One report gal9 unexpectedly competitively binds the ACE2 receptor on host cells, impeding viral entry. Therefore, we hypothesize early recombinant gal9 (rgal9) treatment post infection (pi) may prevent binding of the virus to prone host cells yielding a decreased severity of SARS CoV 2 related disease. To determine the potential of gal9 for treating COVID19, we infected and treated K18 hACE2 mice with a single dose of human rgal9 (rhgal9) or PBS i.p. and monitored 12 days for morbidity. Subgroups of mice were humanely euthanized at 2 and 5 dpi for viral plaque assay, flow cytometry, and protein analysis from lung tissue and BALF. We found that mice treated with rhgal9 during acute phase of infection have improved survival compared to PBS control. At 5 dpi, rhgal9 mice had enhanced viral clearance in the BALF and not in the lung parenchyma. We noted increased CD8 T cell and decreased neutrophil frequencies in the lung at 5 dpi. Finally, BALF had elevated levels of Type 1 IFN at 2 dpi and increased proinflammatory cytokines at 5 dpi. This suggests rhgal9 treatment may be therapeutic for acute COVID19, as rhgal9 with other anti-inflammatory mediator treatments cut associated harmful inflammation. Further studies are required to determine the optimal time, combination and duration of treatment pi to effectively target the gal9 pathway.