Recruitment of alveolar macrophages in bronchoalveolar lavage (BAL) from patients with Interstitial Lung Diseases, analysis of the mechanisms involved

ERNST, GLENDA; JANCIC, CAROLINA ; AUTERI, SANTIAGO; CARO, FABÍAN ; GALÍNDEZ, FERNANDO ; GEFFNER, JORGE ; HAJOS, SILVIA; GRYNBLAT, PEDRO

Atlanta

Conferencia; Chest 2012; 2012

PURPOSE: Recruitment of macrophages in BAL is associated to the development of inflammatory processes during the course of Interstitial Lung Diseases (ILD). However, the mechanisms responsible for macrophage recruitment are poorly defined. Hyaluronan (HA) is a glycosaminoglycan found at high concentrations in BAL from ILD patients. Hyaluronan can regulate different cell functions by interacting with different receptors, among them, CD44 and RHAAM. In the present study we analyzed whether HA was able to induce the chemotaxis of BAL macrophages from ILD patients and the involvement of CD44 and RHAAM in this response. METHODS: Alveolar macrophages were purified from BAL recovered from ILD patients (n=31) by adherence on plastic tissue culture dishes. Migration was measured using a transwell system, in which macrophages were seeded on the upper compartment chamber, and RPMI (diluent), HA (2 ìg/mL) or BAL from ILD patients were added into the lower compartment chamber, either in the presence or absence of hialuronidase (5U/mL). To evaluate the role of CD44 and RHAAM in cell migration, macrophages were preincubated with saturating concentrations of specific blocking monoclonal antibodies, before the onset of the migration assay. The results were expressed as a migration index: migration of macrophages in response to HA or BAL/migration of macrophages toward culture medium. RESULTS: We found that both HA and BAL from ILD patients induced the migration of macrophages: migration index = 2.39 ± 0.12 and 2.64 ± 0.43, respectively (p<0.05). Of note, the presence of hialuronidase abrogated the migration response induced by BAL from ILD patients: % inhibition >95, n=4. Treatment of macrophages with antibodies directed to CD44, markedly decreased the migratory response induced by HA: 1,24 ± 0.08 vs 2.40 ± 0.12 for anti-CD44-treated vs untreated macrophages, respectively, p<0.05). Anti-RHAAM antibodies did not mediate any effect. CONCLUSIONS: BAL from patients with ILD induces the migration of macrophages through a mechanism strongly dependent on the presence of HA. CLINICAL IMPLICATIONS: CD44 could be a novel therapeutic target involved in the recruitment of inflammatory cells in the lung of ILD patients.