Study evaluates if adults with obesity and a history of SARS-CoV-2 infection demonstrate poorer T cell immunity

By Bhavana KunkalikarReviewed by Danielle Ellis, B.Sc.Jul 1 2022

In a recent study published in Obesity, researchers assessed the association between obesity and T cell frequencies specific to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antigen.

Background

Various 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 unit (ICU) admissions, and mortality. This increased adverse impact on people with obesity (PWO) could also be due to immune dysregulation due to obesity. Recent studies have reported that COVID-19-infected PWO displayed lower immunoglobulin G (IgG) antibody titers. However, generating robust T-cell immunity against SARS-CoV-2 among PWO needs further research.  

About the study

In the present study, researchers evaluated if individuals suffering from obesity with a history of COVID-19 infection displayed lower SARS-CoV-2 antigen-specific T-cell immunity compared to control individuals.

The team conducted a cross-sectional analysis of a cohort study that assessed the CD⁴⁺ and CD⁸⁺ cell responses specific to SARS-CoV-2 in individuals three to nine months after polymerase chain reaction (PCR)-confirmed COVID-19 diagnosis. The study included a total of 40 individuals, including 20 adults suffering from obesity with a body-mass index (BMI) of more than 30 kg/m² and 20 matched controls with BMI of less than 30 kg/m². The team obtained patient samples between September and December 2020.

The eligible participants were 18 years and above, provided informed consent, and were diagnosed with COVID-19 three to nine months before the study. The participants were also a part of cohort studies called the all-Ireland infectious disease and obesity immunology group. 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.       

Results

The study results found substantial frequencies of CD⁴⁺ and CD⁸⁺ T cell responses specific to 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 exhibited 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 to SARS-CoV-2 were comparable among people who were and were not diagnosed with obesity. Furthermore, the humoral immunity was similar among the PWO and control individuals.

Conclusion

Overall, the study findings showed that the estimation of CD4+ and CD8+ T cell responses specific to SARS-CoV-2 antigens among people with obesity who have a history of COVID-19 highlighted that antigen-specific T cell frequencies were not affected by obesity.