Chymase-positive mast cells play a role in the vascular component of airway remodeling in asthma

BackgroundThere is increasing evidence to support a role for total mast cells (MCTOT) in the vascular component of airway remodeling in asthma. On the contrary, up to now, no study has addressed the role of chymase-positive mast cells (MCTC) in microvasculature changes.ObjectiveWe sought to assess the role of MCTC in the vascular component of airway remodeling in asthma.MethodsWe recruited 8 patients with mild-to-moderate asthma and 8 healthy volunteers as a control group. Fiberoptic bronchoscopy with endobronchial biopsy was successfully performed in all subjects. Immunostaining was performed for quantification of vessels, vascular endothelial growth factor (VEGF)–positive cells, MCTOT, and MCTC.ResultsCompared with those from healthy subjects, endobronchial biopsy specimens from asthmatic patients showed increased numbers of MCTOT and MCTC and VEGF+ cells (P < .05). In asthmatic patients the number of vessels and the vascular area was also greater than in healthy subjects (P < .05). Additionally, in asthmatic patients the number of MCTC was significantly related to the vascular area (rs = 0.74, P < .01) and to the number of VEGF+ cells (rs = 0.78, P < .01). Moreover, a colocalization study revealed that MCTC were a relevant cellular source of VEGF. Finally, a 6-week treatment with inhaled fluticasone propionate was able to reduce MCTC numbers.ConclusionMCTC can play a role in the vascular component of airway remodeling in asthma, possibly through induction of VEGF.Clinical implicationsSpecific targeting of MCTC might be a tool for treating vascular remodeling in asthma.