The Role of Vitamin D and Vitamin D Receptor in Recurrent Wheezing in Children With Bronchiolitis: Immunological Association With T-lymphocyte Mitochondrial Mass

A prospective study will be conducted involving children under 2 years of age hospitalized for bronchiolitis during the period 2025-2026. Serum levels of 25-OH vitamin D (by chemiluminescence assay), VDR gene polymorphisms (through molecular techniques), and mitochondrial mass of T lymphocytes (by flow cytometry), will be determined in patients at the acute phase of bronchiolitis and in healthy controls. The children will be followed-up for 36 months, with systematic documentation of wheezing episodes and the prognostic value of the biomarkers mentioned above for the later development of recurrent wheezing will be assessed. This study aims to explore the associations between vitamin D levels, VDR polymorphisms and T-cell mitochondrial mass with bronchiolitis severity and the subsequent risk of wheezing episodes. It is hoped that predictive biomarkers for wheezing risk following bronchiolitis and potential therapeutic targets will be identified.