ABSTRACT
Cytomegalovirus (CMV) infection is a major driver of accelerated immunosenescence related to CD28null T cells expansion. CMV infection and these proatherogenic T cells have been independently associated with cardiovascular disease and COVID-19 severity. We have investigated the potential contribution of SARS-CoV-2 to immunosenescence and its relationship with CMV.Innate and adaptive immune subpopulations from mild/asymptomatic SARS-CoV-2 infected (mCOVID-19) individuals, and healthy donors (HD) were immunophenotyped. A significant increase of CD28nullCD57 + CX3CR1+ T cell percentages (CD4+ (P ≤ 0.01), CD8+ (P ≤ 0.01) and TcRγδ (CD4-CD8-) (P ≤ 0.001)) was found in mCOVID-19 CMV + individuals stable up to 12 months post-infection. This expansion did not occur in mCOVID-19 CMV- individuals or in CMV + individuals that were infected post SARS-CoV-2 vaccination (vmCOVID-19). Moreover, mCOVID-19 individuals showed no significant differences with aortic stenosis patients. Thus, individuals coinfected with SARS-CoV-2 and CMV suffer accelerated T cell senescence, which might ultimately lead to an increased risk of cardiovascular disease.
ABSTRACT
Since the discovery of lymphocytes with immunosuppressive activity, increasing interest has arisen in their possible influence on the immune response induced by vaccines. Regulatory T cells (Tregs) are essential for maintaining peripheral tolerance, preventing autoimmune diseases, and limiting chronic inflammatory diseases. However, they also limit beneficial immune responses by suppressing anti-infectious and anti-tumor immunity. Mounting evidence suggests that Tregs are involved, at least in part, in the low effectiveness of immunization against various diseases where it has been difficult to obtain protective vaccines. Interestingly, increased activity of Tregs is associated with aging, suggesting a key role for these cells in the lower vaccine effectiveness observed in older people. In this review, we analyze the impact of Tregs on vaccination, with a focus on older adults. Finally, we address an overview of current strategies for Tregs modulation with potential application to improve the effectiveness of future vaccines targeting older populations.