SARS-CoV-2 infects fat tissue, creates inflammatory storm cloud, study finds

Is SARS-CoV-2 hiding in your fat cells?

A study by Stanford Medicine investigators shows that SARS-CoV-2 can infect human fat tissue. This phenomenon was seen in laboratory experiments conducted on fat tissue excised from patients undergoing bariatric and cardiac surgeries, and later infected in a laboratory dish with SARS-CoV-2. It was further confirmed in autopsy samples from deceased COVID-19 patients.

Obesity is an established, independent risk factor for SARS-CoV-2 infection as well as for the patients’ progression, once infected, to severe disease and death. Reasons offered for this increased vulnerability range from impaired breathing resulting from the pressure of extra weight, to altered immune responsiveness in obese people.

But the new study provides a more direct reason: SARS-CoV-2, the virus that causes COVID-19, can directly infect adipose tissue (which most of us refer to as just plain “fat”). That, in turn, cooks up a cycle of viral replication within resident fat cells, or adipocytes, and causes pronounced inflammation in immune cells that hang out in fat tissue. The inflammation converts even uninfected “bystander” cells within the tissue into an inflammatory state.

“With 2 of every 3 American adults overweight and more than 4 in 10 of them obese, this is a potential cause for concern,” said Tracey McLaughlin, MD, professor of endocrinology.

The findings are described in a study published online Sept. 22 in Science Translational Medicine. McLaughlin and Catherine Blish, MD, PhD, professor of infectious diseases, are the study’s senior authors. Lead authorship is shared by former postdoctoral scholar Giovanny Martínez-Colón, PhD,and graduate student Kalani Ratnasiri.

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