key: cord-0848454-wxypy7ek
authors: Scarpa, Raffaele; Costa, Luisa; Del Puente, Antonio; Caso, Francesco
title: Role of thymopoiesis and inflamm-aging in COVID-19 phenotype
date: 2020-04-15
journal: Pediatrics and neonatology
DOI: 10.1016/j.pedneo.2020.04.001
sha: 161f503c5243a2531350258b8c8bfb9dfbf325f8
doc_id: 848454
cord_uid: wxypy7ek

nan

patients. 2 Furthermore, it is known that characteristic changes occur in the T cell compartment with age and these contribute to the increased incidence and severity of infections in elderly subjects. The production of naïve T cells is severely impaired due to a decreased output of lymphoid cells from the involution of the thymus. 3 The thymus is a central lymphoid organ, which is responsible for the generation of T lymphocytes under the control of the local cellular microenvironment, mainly represented by thymic epithelial cells (TEC). 4 Thymopoiesis leads to the maturation of peripheral naïve T cells with diverse recognition capacity against various microorganisms, such as RNA viruses, and subsets of Tregs to inhibit overactive immune responses. One of the most important age-related immune changes is the impaired generation of primary T cell responses against infection. 3, 4 Further, adult patients with severe case of COVID-19 had a cytokine release storm with an increase of several proinflammatory molecules, including TNF-α, IL-1, and IL-6. 2 Not surprisingly, a progressive propensity toward a proinflammatory phenotype, identified as inflamm-aging, plays a key role in the remodeling of the immune system at older ages, with evidence pointing to an inability to fine-control inflammation. 5 Thus, in our opinion, the role of the thymus could be crucial in the modulation of the immune response toward SARS-CoV-2 leading to a less severe phenotype in children when compared with those in adult COVID-19 patients. On the other hand, inflamm-aging associated with the absence of thymopoietic mechanisms could be a predisposing condition that sustains the cytokine release storm as is most often reported in adult COVID-19 subjects, especially in the older COVID-19 patients.

Further studies are needed to clarify the impact of thymopoiesis and inflamm-aging on COVID-19 phenotypes. These studies could be useful not only for considering new therapeutic strategies but also for better addressing the studies that focus on inflammatory profiles and biomarkers of COVID-19 patients for pneumonia risk stratification.

Clinical characteristics of novel coronavirus disease 2019 (COVID-19) in newborns, infants and children

Dysregulation of immune response in patients with COVID-19 in Wuhan, China

T cells, aging and senescence

The Role of the Thymus in the Immune Response

Age and Age-Related Diseases: Role of Inflammation Triggers and