Takabayashi et al. present novel findings in this issue on the distribution and protease secretion of mast cells (MC) found in nasal polyps from subjects with chronic rhinosinusitis (CRSwNP) (J Allergy Clin Immunol 2012; 130:410-420.e5). The authors compared MC from the epithelium, glands, and submucosa of CRSwNP with uncinate biopsy tissue (UT) from subjects with CRS without nasal polyps (CRSsNP) and control subjects.
They found mast cells numbers were highly increased in NP epithelium and glands, in particular, as compared to UT from CRSsNP and control subjects. Further, the MC populations in NP were distinguishable on the basis of their protease profile. Mast cells from the NP epithelium were tryptase-carboxypeptidase A3 (CPA3)-positive/chymase-negative, while MC from NP glands were tryptase-CPA3-chymase-positive.
The authors note clear expansion in MC numbers that they suggest could be the result of increased migration and accumulation as well as proliferation. Since mast cell tryptase can activate protease-activated receptor (PAR) 2, which facilitates allergic inflammation, and mast cell chymase can activate PAR-1 signaling and is a potent glandular secretagogue, the results of Takabayashi et al suggest that mast cells localized in submucosal glands may be well positioned to drive important features of the inflammatory response associated with chronic rhinosinusitis and nasal polyp formation.
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