Although having an apple shape is not nearly as healthy as eating an apple daily, it may keep the doctor away. Now, Japanese researchers have demonstrated that if they catch COVID-19, people who carry their weight in their bellies may be at greater risk of poor outcomes.
Researchers from Tokyo Medical and Dental University (TMDU) discovered in a study that was published last month in Proceedings of the National Academy of Sciences that having too much belly fat is linked to more inflammation and death in Japanese COVID-19 patients.
A dangerous condition known as a “cytokine storm” occurs in some COVID-19 patients. This condition involves severe inflammation that dramatically affects breathing and can result in death. Despite the fact that it is difficult to anticipate which patients will go through this occasion, conditions, for example, hypertension, diabetes, kidney infection, and weight, are recognized risk factors.
One of the lead authors, Tadashi Hosoya, states, “While treating patients with COVID-19, we noticed that obese patients tended to experience more severe disease courses and worse outcomes (A, B).” As a result, we hypothesized that the accumulation of visceral adipose tissue might be a way to identify high-risk patients and fuel systemic inflammatory responses in COVID-19.”
“As a result, we hypothesized that visceral adipose tissue accumulation fueled systemic inflammatory responses in COVID-19 and could be used to identify high-risk patients.”
Lead authors, Tadashi Hosoya
The researchers tested this with two kinds of obese mice: ob/ob mice, which are more likely to gain weight in their abdomen, and db/db mice, which gain weight all over. Both types of mice have impaired leptin signaling, which controls appetite and causes them to overeat and become obese. After infecting these two types of obese mice and non-obese control mice with mouse-adapted SARS-CoV-2, the researchers monitored the mice for signs of inflammation, damage to their lungs, and even death.
Senior author Shinsuke Yasuda says, “The results were very striking.” After being infected with SARS-CoV-2, all of the ob/ob mice passed away, but the majority of the non-obese control mice and even the obese db/db mice survived (C).
They noted that compared to db/db mice, ob/ob mice produced more pro-inflammatory factors. Importantly, these obese mice’s survival rates were partially but significantly improved by blocking interleukin-6 (IL-6).
It should be noted that obese mice can be made “lean” by giving them a leptin supplement to prevent weight gain, and these mice were more likely to survive the SARS-CoV-2 infection than their obese counterparts. However, the mice were unable to survive the infection if the leptin supplement was administered after they had already become obese (D).
Lead author Seiya Oba states, “Our findings suggest that excessive adipose tissue is related to activation of the cytokine storm and delayed elimination of SARS-CoV-2, thus predicting mortality.”
Asian populations’ COVID-19 mortality rates were significantly higher than White populations’. This could be because Asian populations are more likely to have obesity in the shape of apples.
These findings suggest that obese patients with excess belly fat would benefit most from this treatment strategy because anti-inflammatory therapies, such as IL-6 blockers, are already available. Patients’ outcomes will hopefully improve as a result of learning more about COVID-19.
More information: Tadashi Hosoya et al, Apple-shaped obesity: A risky soil for cytokine-accelerated severity in COVID-19, Proceedings of the National Academy of Sciences (2023). DOI: 10.1073/pnas.2300155120
