The coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus (SARS-CoV-2), causes severe illness in high-risk populations. These include the elderly and those with underlying health conditions such as diabetes, hypertension, heart disease, and obesity.
Researchers at the University of Miami Miller School of Medicine, USA, revealed that the spike-specific immunoglobulin G antibodies in obese people are negatively associated with body mass index (BMI) and serum levels of proinflammatory and metabolic markers of pulmonary inflammation.
The study, published in the pre-print journal medRxiv*, also found that higher BMI is tied to a higher infection rate with SARS-CoV-2.
Obesity and COVID-19
The SARS-CoV-2 is actively spreading worldwide. It has infected more than 78 million people and killed over 1.71 million. Information about human immune responses to SARS-CoV-2 infection is limited.
However, recent studies have shown that some people are more likely to get infected and develop a more severe illness than others. Older adults and those with comorbidities are more likely to develop severe COVID-19. Recently, studies have also shown that obesity may predispose a person to severe COVID-19.
Recently published data showed that chronic low-grade systemic inflammation, called inflammaging, is the primary cause of the cellular and molecular changes induced by SARS-CoV-2. It is also responsible for the highest mortality rates.
Obesity-induced persistent local and systemic inflammation contributed to the impairment of immune cells and reduced immunity.
The inflammation found in obese individuals leads to several debilitating chronic diseases, including cancer, atherosclerosis, type 2 diabetes, and inflammatory bowel disease. Obesity is an additional risk factor for severe COVID-19.
To arrive at the study findings, the researchers evaluated the effects of obesity on the secretion of SARS-CoV-2-specific IgG antibodies in the blood of COVID-19 patients.
The team measured serum levels of SARS-CoV-2 Spike-specific IgG antibodies in lean and obese COVID-19 patients, as well as in uninfected controls, using an enzyme-linked immunosorbent assay (ELISA) test.
First, the study found that BMI was higher in positive SARS-CoV-2 patients compared to uninfected controls. This suggests that higher BMI is associated with severe respiratory symptoms. During hospital admission, those with higher BMI have severe respiratory symptoms such as cough, fever, shortness of breath, and hypoxia or low oxygen levels.
The study findings also showed that spike-specific IgG antibodies in obese people are negatively linked to BMI and serum levels of proinflammatory and metabolic markers of inflammaging and pulmonary inflammation.
The data collected could help develop an inflammatory signature with a strong predictive value for immune dysfunction, which can be used as a therapeutic target to improve humoral immunity among obese people.
Another result from the present study is the negative association of SARS-CoV-2 IgG antibodies with markers of pulmonary inflammation (SAA, CRP, ferritin) in our cohort of COVID-19 patients,” the researchers explained.
“These are major inflammatory mediators and markers of inflammatory lung injury in patients with catastrophic acute respiratory distress syndrome, which is a primary consequence of COVID-19,” they added.
The research findings support that SARS-CoV-2 infection, akin to influenza, may induce self-tolerance breakdown to autoantigens in obese people. It is essential to consider them as a high-risk group, who are more likely to develop severe symptoms due to COVID-19.
Moreover, the quality of antibody response in obese COVID-19 patients is crucial for future vaccination efforts to prevent SARS-CoV-2 infection and COVID-19-associated complications. Obese people may also benefit if they are among the first to receive a vaccination.
medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.
- Frasca, D., Reidy, L., Cray, C., Diaz, A., Romero, M., Kahl, K., and Blomberg, B. (2020). Effects of obesity on serum levels of SARS-CoV-2-specific antibodies in COVID-19 patients. medRxiv. doi: https://doi.org/10.1101/2020.12.18.20248483, https://www.medrxiv.org/content/10.1101/2020.12.18.20248483v1