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

NCT07700134 | Active Not Recruiting

• 2 other identifiers: 127319/24.10.252025 Grant
• Study Type: observational
• Target: 130
• Locations: 1 country
• Sites: 1

Brief Summary

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.

Conditions

Bronchiolitis Acute; Wheezing; RSV

Keywords

bronchiolitis; mitochondrial mass; recurrent wheezing; 25-hydroxy vitamin D; Vitamin D receptor

Outcome Measures

Primary Outcomes (1)

• Mitochondrial Mass in T-lymphocytes

  The mitochondrial mass of T-lymphocytes will be measured by flow cytometry, utilizing peripheral blood samples obtained during routine complete blood count (CBC) draws. These measurements will be compared between children with bronchiolitis and healthy controls.

  Within 12 hours upon childs admission

Secondary Outcomes (2)

• 25-OH vitamin D levels

  1-3 days upon admission

• Vitamin D Receptor Polymorphisms

  During the 2025-2026 season (blood samples will be refrigerated and analysed later)

Study Arms (2)

Neonates and infants with bronchiolits

Infants \<24months who were hospitalized with bronchiolitis during the season 2025-2026

Other: No Intervention: Observational Cohort

Healthy controls

The control group will consist of otherwise healthy infants \<24 months of age who were hospitalized during the same time period for non-infectious causes. Children will be excluded from the control group if they have any underlying bone, metabolic, or endocrine disorders, or if they are hospitalized for any condition known to increase oxidative stress or alter the immune response.

Other: No Intervention: Observational Cohort

Interventions

No Intervention: Observational Cohort OTHER

No intervetion

Healthy controls; Neonates and infants with bronchiolits

Eligibility Criteria

• Age: 0 Days - 24 Months
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Child (0-17)
• Sampling Method: Non-Probability Sample

Study Population

The study will include children under 2 years of age who are diagnosed with bronchiolitis and hospitalized to the Second Pediatric Department and the Neonatal Unit of the 1st Pediatric Department of the National and Kapodistrian University of Athens at "Aghia Sofia" Children's Hospital. Diagnosis will be established according to the 2021 NICE criteria for bronchiolitis. The control group will consist of healthy children without bronchiolitis, matched to patients for gestational age, chronological age, and sex, at a 1:4 ratio. Controls will be recruited during the same period as the patients to ensure comparability of the two groups with respect to seasonality, which is known to affect serum vitamin D levels.

You may qualify if:

• The study will include children under 2 years of age who are diagnosed with bronchiolitis and hospitalized to the Second Pediatric Department and the Neonatal Unit of the 1st Pediatric Department of the National and Kapodistrian University of Athens at "Aghia Sofia" Children's Hospital. Diagnosis will be established according to the 2021 NICE criteria for bronchiolitis.
• The control group will consist of healthy children without bronchiolitis, matched to patients for gestational age, chronological age, and sex, at a 1:4 ratio. Controls will be recruited during the same period as the patients to ensure comparability of the two groups with respect to seasonality, which is known to affect serum vitamin D levels.
• Εxclusion Criteria:
• Patients will be excluded from the study if they have a history of congenital heart disease, cystic fibrosis, bronchopulmonary dysplasia, immunodeficiency, use of immunosuppressive agents, prematurity with a gestational age of \< 32 weeks, or if their guardians refuse their participation in the study.

Sponsors & Collaborators

• Aghia Sophia Children's Hospital of Athens: collaborator
• National and Kapodistrian University of Athens: lead

Study Sites (1)

"Aghia Sofia" Children's Hospital

Athens, Attica, 11527, Greece

Location

Biospecimen

Retention: SAMPLES WITH DNA

Blood samples will be retained for the genetic analysis of Vitamin D Receptor (VDR) polymorphisms to evaluate their association with disease severity. Biospecimens will be collected and stored strictly after providing a detailed explanation of the study protocol and obtaining written informed consent from the parents or legal guardians.

MeSH Terms

Conditions

Respiratory Sounds; Bronchiolitis

Condition Hierarchy (Ancestors)

Signs and Symptoms, Respiratory; Signs and Symptoms; Pathological Conditions, Signs and Symptoms; Bronchitis; Respiratory Tract Infections; Infections; Bronchial Diseases; Respiratory Tract Diseases; Lung Diseases, Obstructive; Lung Diseases

Study Officials

• Tania Siahanidou, Professor

  Medicine department, National and Kapodistrian University of Athens, Greece

  STUDY CHAIR

Study Design

• Study Type: observational
• Observational Model: COHORT
• Time Perspective: PROSPECTIVE
• Target Duration: 3 Years
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Resident Physician in Pediatrics and PhD Candidate

Study Record Dates

• First Submitted: July 7, 2026
• First Posted: July 13, 2026
• Study Start: December 1, 2025
• Primary Completion (Estimated): December 1, 2028
• Study Completion (Estimated): December 1, 2028
• Last Updated: July 13, 2026

Record last verified: 2026-07

Data Sharing

• IPD Sharing: Will not share

Locations

GR (1)