BATON ROUGE, Louisiana - A hormone that connects the body's metabolism and immune response system may explain why COVID-19 is so dangerous for people with obesity.
"The problem for people with obesity is that their leptin levels are always high, and that can affect the response to a COVID-19 infection," said Candida Rebello, PhD, RD, lead author of a new paper that traces the link between obesity and the virus.
The hormone leptin regulates appetite and metabolism. Leptin also regulates the cells that fight infection. Leptin is produced by fat cells, and to a lesser extent by tissues in the lungs. The more fat a person has, the more leptin circulates in their body.
Elevated leptin levels hamper the body's ability to fight off infections, in the lungs and elsewhere, Dr. Rebello said. High leptin levels promote a low-grade systemic inflammatory state.
"If you have obesity, there are a number of underlying health issues that make it more difficult for you to fight off a COVID-19 infection," said John Kirwan, PhD, Pennington Biomedical Executive Director and a co-author of the review. "Your entire body, including your lungs, may be inflamed. Your immune response is likely compromised, and your lung capacity reduced.
"Add in a virus that further weakens the body's ability to fight infection, that can limit the body's ability to control lung inflammation, and you have the recipe for disaster."
COVID-19 vaccine developers should take the immunocompromised state resulting from obesity into consideration, in much the same way they would advancing age.
The researchers say the role of leptin in COVID-19's development bears investigation along with the viral proteins that alter the immune systems of people with obesity. One potential avenue of treatment may be a drug that prevents inflammatory responses to the virus.
Another potential avenue of investigation includes examining how proinflammatory fat tissue in people with obesity might contribute to activating fewer infection-fighting cells and why those cells die more quickly.
The article "Obesity, the Most Common Comorbidity in SARS-CoV-2: Is Leptin the Link?" was published in the International Journal of Obesity. The authors are:
- Candida Rebello, PhD, RD, Postdoctoral Researcher in Dr. Frank Greenway's Pharmacology-based Clinical Trials Laboratory.
John Kirwan, PhD, Executive Director of Pennington Biomedical and Director of the Integrated Physiology and Molecular Metabolism Laboratory.
Frank Greenway, MD, Professor and Chief Medical Officer.
This work was supported in part by award number U54 GM104940 from the National Institute of General Medical Sciences of the National Institutes of Health, which funds the Louisiana Clinical and Translational Science Center. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.
About the Pennington Biomedical Research Center
The Pennington Biomedical Research Center is at the forefront of medical discovery as it relates to understanding the triggers of obesity, diabetes, cardiovascular disease, cancer and dementia. The Center conducts basic, clinical, and population research, and is affiliated with Louisiana State University. The research enterprise at Pennington Biomedical includes over 450 employees within a network of 40 clinics and research laboratories, and 13 highly specialized core service facilities. Its scientists and physician/scientists are supported by research trainees, lab technicians, nurses, dietitians, and other support personnel. Pennington Biomedical is located in state-of-the-art research facilities on a 222-acre campus in Baton Rouge, Louisiana. For more information, see http://www.pbrc.edu.
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International Journal of Obesity