Targeting galectin-3 to intervene COVID-19

Project Summary/Abstract The COVID-19, caused by the severe acute respiratory syndrome coronavirus 2 (SARSCoV-2), is a global pandemic with catastrophic consequences for healthcare systems and populations. The increased morbidity and mortality in older persons and those with diabetes (12-22%) and hypertension (23.7-30%) is particularly concerning due to high incidence of diabetes throughout the world. The angiotensin-converting enzyme 2 (ACE2) receptor serves as a high affinity receptor for SARSCoV-2 to enter the lungs. Interestingly, patients with diabetes, who are treated with ACE inhibitor and angiotensin II type-I receptor blocker, highly express ACE2 making them more susceptible to COVID-19. For infection and pathogenesis, virus needs to attach and penetrate a thick glycan rich mucus and glycocalyx before binding its entry-receptor and galectin-3 (Gal3) is believed to play a role in the enhanced attachment of SARSCoV-2 through binding to the spike glycoprotein. Gal3 promotes viral infections and enhances of pro-inflammatory cytokines such as interleukin (IL)-6, tumor necrosis factor (TNF)-α. We confirmed Gal3 binding to SARSCoV-2 spike glycoprotein. Interestingly, increased levels of Gal3 are associated with prediabetes, diabetes, and hypertension. Gal3 binds also directly to the insulin receptor (IR) and inhibits downstream IR signaling promoting obesity-mediated inflammation (macrophage-derived Gal3) and insulin resistance in type 2 diabetes (T2D). These fundamental observations elucidate a novel role of Gal3 that promotes viral infection and uncontrolled release of pro-inflammatory/anti- inflammatory cytokines and suggest that specific inhibition of Gal3 may represent a promising therapeutic strategy not only treat COVID-19, but also COVID-19 impacted diabetic patients. Our scientific premise is that we have developed a very potent Gal3 antagonist, named TFD100, from a natural dietary source (PNAS publication PMID: 23479624). In our preliminary studies, TFD100 inhibited replication of SARSCoV-2. TFD100 reversed Gal3 mediated inhibition of IR activation. TFD100 also decreased fasting glucose and improved glucose tolerance and insulin sensitivity. Here, we propose to investigate the therapeutic utilities of TFD100 for treating COVID-19 and COVID-19 impacted T2D in a relevant COVID-19 "humanized" mouse model (human ACE-2 transgenic mice). Following drug treatment of SARSCoV-2 infected mice, viral load (primary endpoint) and resolution of dysregulated inflammation (secondary endpoint) will be measured. To investigate TFD100's ability to intervene COVID-19 impacted T2D in hACE-2 mice, obese- induced T2D will be made first in these mice with high fat diet followed by SARSCoV-2 infection. Following drug treatment, glucose and insulin tolerance as well as viral load (primary endpoints) will be measured. For other endpoints, resolution of host-response as dysregulated inflammation (cytokine storm) and restoration of insulin signaling will be measured by the frequency of pro-inflammatory/anti-inflammatory biomarkers (Gal3, ACE-2, and other proteins) in blood, lung, liver, fat, and muscle. This also includes determination of changes in pro/anti-inflammatory immune cell frequencies denoted by polarization of macrophages and helper-T (Th) cells. Gal3 inhibition is anticipated to be a significant advancement in the arsenal against SARSCoV-2 impacted T2D, and possibly SARSCoV-2 infection as an antiviral therapy.