In a recent study published in obesityresearchers assessed the association between obesity and T-cell frequencies specific for the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antigen.
Several studies have reported that obesity is a risk factor for developing severe coronavirus disease 2019 (COVID-19), leading to increased COVID-19-related hospitalizations, intensive care (ICU) admissions and mortality. This increased adverse impact on obese people (PWO) may also be due to immune dysregulation resulting from obesity. Recent studies have reported that COVID-19 infected PWO showed lower immunoglobulin G (IgG) antibody titers. However, generating robust T cell immunity to SARS-CoV-2 in PWO requires further investigation.
About the study
In the present study, researchers evaluated whether individuals who were obese with a history of COVID-19 infection exhibited lower SARS-CoV-2 antigen-specific T-cell immunity compared to control subjects.
The team conducted a cross-sectional analysis of a cohort study assessing CD4+ and CD8+ cell responses specific for SARS-CoV-2 in individuals three to nine months after polymerase chain reaction (PCR) confirmed COVID-19 diagnosis. The study involved a total of 40 subjects, including 20 obese adults with a body-mass index (BMI) greater than 30 kg/m²2 and 20 matched controls with a BMI less than 30 kg/m2† The team obtained patient samples between September and December 2020.
Eligible participants were 18 years of age and older, gave informed consent, and were diagnosed with COVID-19 three to nine months before the study. The participants were also part of cohort studies, the all-Ireland group for infectious diseases and obesity immunology. Furthermore, the team performed flow cytometric analysis and measured the Igg antibody titers against SARS-CoV-2 receptor binding domain (RBD), spike 1 subunit (S1), S2 subunit and nucleocapsid (N) protein.
The study results found substantial frequencies of CD4+ and CD8+ T cell responses specific for SARS-CoV-2 that produced interferon-γ (IFNγ) against SARS-CoV-2 S and membrane peptides. Cytokine-producing T cells were correlated with increased protection against SARS-CoV-2 infections. The team observed CD4+ and CD8+ T cell responses to both membrane and S peptides.
PWO also showed strong T cell responses specific to SARS-CoV-2, with no variations between the frequencies of CD4+ and CD8+ T cells that produced IFNγ against the membrane and S-peptide pools. Similarly, frequencies corresponding to cytokine-producing T cells specific for SARS-CoV-2 were similar in people who were and were not diagnosed with obesity. In addition, humoral immunity was similar between the PWO and control subjects.
Overall, the study results showed that the estimation of CD4+ and CD8+ T cell responses specific for SARS-CoV-2 antigens among obese people with a history of COVID-19 emphasized that antigen-specific T-cell frequencies were not affected by obesity.
Wrigley Kelly, NE, Kenny, G., Cassidy, FC, Garcia-Leon, AA, De Barra, C., Mallon, PWG, Hogan, AE, and O’Shea, D. (2022). Obese individuals who survive SARS-CoV-2 infection have retained antigen-specific T cell frequencies. obesity. doi† https://doi.org/10.1002/oby.23526 https://onlinelibrary.wiley.com/doi/10.1002/oby.23526
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