Functional characterization of small and large alveolar macrophages in sarcoidosis and idiopathic pulmonary fibrosis compared with non-fibrosis interstitial lung diseases

Article type: Research Article

Authors: El Fakihi, Sara^{a; b} | El Allam, Aicha^{a; c} | Tahoune, Hicham^{a; d} | Najimi, Nouhaila^{a; e} | Kadi, Chaimae^{a; f} | Ibrahimi, Azeddine^{a; b} | Bourkadi, Jamal-Eddine^{g; h} | Seghrouchni, Fouad^{a; *}

Affiliations: [a] , Rabat, Morocco | [b] Medical Biotechnology Laboratory, Faculty of Medicine and Pharmacy, University Mohammed V, Rabat, Morocco | [c] Department of Immunology, School of Medicine, Yale University, New Haven, CT, USA | [d] Department of Microbiology, CHU Mohammed VI, Tangier, Morocco | [e] Laboratory of Human Pathologies, Department of Biology, Faculty of Sciences, University Mohammed V, Rabat, Morocco | [f] Department of Biology, Faculty of Sciences, University Abdelmalek Essaadi, Tetouan, Morocco | [g] Pneumo-Phtisiology Department, Moulay Youssef Hospital, Rabat, Morocco | [h] Faculty of Medicine and Pharmacy, University Mohammed V, Rabat, Morocco

Correspondence: [*] Corresponding author: Fouad Seghrouchni, Mohammed VI Center of Research and Innovation, Rabat, Morocco. Tel.: +212 66 64 78 51 30; E-mail: f.seghrouchni@cm6.ma.

Abstract: BACKGROUND: Sarcoidosis is a granulomatous disease that mostly affects the lungs. Advanced tissue injury caused by this disease can progress to pulmonary fibrosis with similar characteristics shared with idiopathic pulmonary fibrosis (IPF). The initial presentations of both sarcoidosis and IPF may be shared with other interstitial lung diseases (ILDs). Two populations of macrophages have been described in the alveolar space: small alveolar macrophages (AMs) and large alveolar macrophages. Despite their protective function, these cells may also play a role in the initiation and maintenance of inflammation leading to fibrosis. OBJECTIVE: The aim of this study was the functional characterization of small and large AM subpopulations in sarcoidosis and IPF as a pathology with respectively mild and advanced tissue injury causing fibrosis, in comparison with non-fibrosis ILDs. METHODS: Activation and adhesion surface markers as well as functions of small and large AMs isolated from bronchoalveolar lavage (BAL) were assessed by Flow Cytometry within patients with confirmed sarcoidosis (n= 14), IPF (n= 6), and non-fibrosis ILDs (n= 9). RESULTS: Our results showed that small AMs are immunologically more active, which may be important for airway inflammation. They are also proportionally more abundant in IPF, and therefore they may be more involved in a fibrosis process associated with the down-regulation of HLA-DR, LeuCAM, and CD62L expression. In Sarcoidosis, the inflammatory process appears to be associated with up-regulation of CD38 expression and oxidative burst activity. CONCLUSION: A relevant potential of the activation and adhesion markers as well as oxidative burst activity expressed on small and large AMs, in the perspective of differential diagnosis of sarcoidosis and IPF.

Keywords: Sarcoidosis, idiopathic pulmonary fibrosis, non-fibrosis ILDs, small alveolar macrophages, large alveolar macrophages

DOI: 10.3233/HAB-230005

Journal: Human Antibodies, vol. 31, no. 3, pp. 59-69, 2023