MacroMARS: Macrophages, GM-CSF and MARS Proteinosis

Sponsor

Assistance Publique - Hôpitaux de Paris (Other)

Overall Status

Recruiting

CT.gov ID

NCT04811274

Collaborator

(none)

Enrollment

Location

Anticipated Duration (Months)

0.6

Patients Per Site Per Month

Study Details

Study Description

Brief Summary

Mutations in the MARS gene encoding methionyl-tRNA synthetase are responsible for a genetic form of alveolar proteinosis (PAP), but the pathophysiological mechanisms of the respiratory phenotype are not known.

The main hypothesis is that the PAP phenotype in these patients is secondary to a defective clearance of the surfactant by the alveolar macrophages.

The main objective of the study is to study the clearance capacity of lipoproteinaceous material by macrophages of patients with MARS related PAP. This will be investigate in cultured macrophages derived from peripheral blood monocytes of patients (patients with MARS related PAP) and controls (patients without MARS related PAP).

Condition or Disease	Intervention/Treatment	Phase
Pulmonary Alveolar Proteinosis (PAP) MARS Genetic Mutation	Biological: Blood collection Biological: Bronchoalveolar lavage fluid collection

Detailed Description

Pulmonary alveolar proteinosis (PAP) is a rare respiratory disease characterized by the accumulation of lipoproteinaceous material within the pulmonary alveoli, resulting in the majority of cases from a defective clearance of the surfactant by intra-alveolar macrophages.

Mutations in the MARS gene encoding methionyl-tRNA synthetase are responsible for a genetic form of alveolar proteinosis, but the pathophysiological mechanisms leading to mutations in the respiratory phenotype are not known.

The main hypothesis is that the alveolar proteinosis phenotype in these patients is secondary to a defective clearance of the surfactant by the alveolar macrophages.

The subjects and the controls will be included during a hospitalization during which a blood sample and a bronchoscopy with broncoalveolar lavage must be performed as part of their care.

Study Design

Study Type:

Observational

Anticipated Enrollment :

20 participants

Observational Model:

Case-Control

Time Perspective:

Prospective

Official Title:

Study of Macrophage Function and of the GM-CSF Signaling Pathway in Alveolar Proteinosis by Mutations of the MARS Gene

Actual Study Start Date :

Jun 7, 2021

Anticipated Primary Completion Date :

Jun 7, 2024

Anticipated Study Completion Date :

Jun 7, 2024

Arms and Interventions

Arm	Intervention/Treatment
Patients Minor patients with alveolar proteinosis by mutations of the MARS gene.	Biological: Blood collection 2 to 5 ml Biological: Bronchoalveolar lavage fluid collection 5 to 25 ml
Controls Minors patients without alveolar proteinosis.	Biological: Blood collection 2 to 5 ml Biological: Bronchoalveolar lavage fluid collection 5 to 25 ml

Arm

Intervention/Treatment

Patients

Minor patients with alveolar proteinosis by mutations of the MARS gene.

Biological: Blood collection

2 to 5 ml

Biological: Bronchoalveolar lavage fluid collection

5 to 25 ml

Controls

Minors patients without alveolar proteinosis.

Biological: Blood collection

2 to 5 ml

Biological: Bronchoalveolar lavage fluid collection

5 to 25 ml

Outcome Measures

Primary Outcome Measures

Measurement of the clearance [Day 0]
Measurement of the clearance of abnormal lipo-proteinaceous material (from patients) at 48h of culture by cultured macrophages derived from peripheral blood monocytes from patients and controls. Microscopic examination of cell samples prepared on slide after cytospin and stained with oil red'O.

Secondary Outcome Measures

Measurement of the clearance after supplementation with methionine [Day 0]
Measurement of the clearance of abnormal lipo-proteinaceous material (from patients) at 48h culture with methionine supplementation in culture medium by cultured macrophages derived from peripheral blood monocytes from patients and controls. Microscopic examination of cell samples prepared on slide after cytospin and stained with oil red'O.
Cellular phenotyping and study of the GM-CSF pathway [Day 0]
Description : Study the impact of mutations on the cell phenotype and the GM-CSF signalling pathway. (i) CD11b and CD49d cell immunostaining which are surface markers of healthy alveolar macrophages ; (ii) measurement of the level of intracellular phosphorylation of STAT5 by flow cytometry; and (iii) measurement of the level of expression of the SPI1, PPARγ and ABCG1 genes by quantitative PCR. These measurements will be performed in cultured macrophages derived from peripheral blood monocytes of patients and controls, but also in alveolar macrophages directly isolated from the BAL fluid of patients and controls. All these measurements will be performed in response to incubation with GM-CSF.

Eligibility Criteria

Criteria

Ages Eligible for Study:

N/A to 17 Years

Sexes Eligible for Study:

All

Accepts Healthy Volunteers:

Inclusion Criteria:

Minors from 0 to 17 years hospitalized for their care at Necker Enfants Malades hospital and for whom a blood sample and a bronchoscopy with bronchoalveolar lavage must be performed as part of their care
Information and consent of the holders of parental authority and the patient