Abstract
Rationale: Mast cells (MCs) are implicated in chronic inflammation and tissue remodeling. However, a systematic investigation of pulmonary MCs/MC chymase is yet missing in idiopathic pulmonary arterial hypertension (IPAH) and chronic obstructive pulmonary disease (COPD).
Methods: Lung tissues obtained from donors, and IPAH and COPD patients undergoing lung transplantation were formalin-fixed and paraffin-embedded, followed by toluidine blue (TB) staining for MCs and immunostaining for MC chymase. Total and perivascular MCs were determined by counting MCs under light microscope equipped with computerized morphometric system. Perivascular MCs were categorized as granulated and degranulated and an index of granulation (IOG) [(number of granulated/degranulated MCs)] was determined.
Results: Pulmonary MCs were prevalent in IPAH and COPD patients; furthermore, perivascular MC count was significantly increased in the resistance vessels of patients (p<0.05 vs donors). Notably, the IOG was decreased by about 8 and 5 folds in IPAH and COPD patients, respectively (vs donors). Chymase-positive MCs were increased by 16 and 10 folds in IPAH and COPD patients, respectively (vs donors). The perivascular chymase-positive MCs were significantly increased in IPAH and COPD patients (p<0.05 vs donors). Interestingly, the chymase-positive MC subpopulations were about 42% and 48% of the MCs in IPAH and COPD patients, respectively; whereas it was 10% in donors.
Conclusion: The chymase released from activated perivascular MCs may potentially contribute to the pulmonary vascular remodeling in IPAH and COPD. Future studies are essential to substantiate the findings and to elucidate underlying pathomechanisms.
- © 2011 ERS
