Clonal dynamics of SARS-CoV-2-specific T cells in children and adults with COVID-19

Children infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) develop less severe coronavirus disease 2019 (COVID-19) than adults. The mechanisms for the age-specific differences and the implications for infection-induced immunity are beginning to be uncovered. We show by longitudinal multimodal analysis that SARS-CoV-2 leaves a small footprint in the circulating T cell compartment in children with mild/asymptomatic COVID-19 compared to adult household contacts with the same disease severity who had more evidence of systemic T cell interferon activation, cytotoxicity and exhaustion. Children harbored diverse polyclonal SARS-CoV- 2-specific naive T cells whereas adults harbored clonally expanded SARS-CoV-2-specific memory T cells. More naive interferon-activated CD4+ T cells were recruited into the memory compartment and recovery was associated with the development of robust CD4+ memory T cell responses in adults but not children. These data suggest that rapid clearance of SARS-CoV-2 in children may compromise their cellular immunity and ability to resist reinfection. HIGHLIGHTSO_LIChildren have diverse polyclonal SARS-CoV-2-specific naive T cells C_LIO_LIAdults have clonally expanded exhausted SARS-CoV-2-specific memory T cells C_LIO_LIInterferon-activated naive T cells differentiate into memory T cells in adults but not children C_LIO_LIAdults but not children develop robust memory T cell responses to SARS-CoV-2 C_LI O_FIG O_LINKSMALLFIG WIDTH=177 HEIGHT=200 SRC="FIGDIR/small/478400v1_ufig1.gif" ALT="Figure 1"> View larger version (44K): org.highwire.dtl.DTLVardef@e9586org.highwire.dtl.DTLVardef@17aaf37org.highwire.dtl.DTLVardef@18575e0org.highwire.dtl.DTLVardef@fde4ae_HPS_FORMAT_FIGEXP M_FIG C_FIG

Effects of 12 weeks of Multi-nutrient supplementation on the Immune and Musculoskeletal systems of Older Adults in Aged-Care (The Pomerium Study): Protocol for a Randomised Controlled Trial

IntroductionImmunosenescence leads to increased morbidity and mortality associated with viral infections and weaker vaccine responses. This has been well documented for seasonal influenza and the current pandemic with Sars-Cov2, which disproportionately impact older adults, particularly those in residential aged care facilities. Inadequate nutrient intake associated with impaired immunity, respiratory and muscle function are likely to augment the effects of immunosenescence. In this study, we test whether the effects of inadequate nutrition can be reversed by multi-nutrient supplementation, consequently enhancing vaccine responses, reducing the risk of viral infections, and improving respiratory and muscle function. Methods and analysisThe Pomerium Study is a 12-week, single-blinded, randomised, placebo-controlled trial testing the effects of two daily servings of an oral multi-nutrient supplement (330 kcal, 20g protein, 1.2g CaHMB, 449mg calcium, 520IU vitamin D3, and 25 vitamins and minerals) on the immune system and muscle and respiratory function of older adults in aged-care in Melbourne, Australia. 160 older adults ([≥]75 years old) will be recruited from aged-care facilities and randomised to treatment (multi-nutrient supplement) or control (usual care). Primary outcome is the change in T-cell subsets CD8+ and CD28null counts at 4 and 12 weeks post-intervention. Secondary outcomes measured at baseline and after 12 weeks post-intervention are multiple markers of immunosenescence, body composition (bioimpedance), handgrip strength (dynamometer), physical function (short physical performance battery), respiratory function (spirometry), and quality of life (EQ-5D-3L). Incidence and complications of COVID-19 and/or viral infections (i.e., hospitalisation, complications, or death) will be recorded throughout the trial. DiscussionIf the Pomerium Study demonstrates efficacy and safety of a multi-nutrient supplement on immune, muscle and respiratory function, it may be suitable as a strategy to reduce the adverse outcomes from seasonal influenza and viral infections such as COVID-19 in older adults in aged-care. Funding, Ethics, Registration and DisseminationThe study is funded by the Australian Medical Research Future Fund. It is approved by Melbourne Health Human Research Ethics Committee (Ref No. HREC/73985/MH-2021, ERM Ref No. RMH73985, Melbourne Health Site Ref No. 2021.115), and registered at ANZCTR (12621000420842). Results will be published in peer-reviewed journals and made available to aged-care stakeholders, including providers, residents, and government bodies. Article Summary Strengths and LimitationsO_LIThis is the first study performing a comprehensive immune, respiratory and functional assessment in aged care residents after receiving a multi-nutrient solution that is commercially available. C_LIO_LIOur design and tested intervention assure that the results of the study will be rapidly translated into practice. C_LIO_LIThe main limitation is that any biological effect observed cannot be attributed to one component of the multi-nutrient supplement. C_LIO_LIAnother limitation is that the potential effect of group differences in energy intake on outcomes can only be monitored by assessing regular dietary intake and weight changes during the study period. C_LI