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Published on: May 27, 2015
Involvement of premacular mast cells in the pathogenesis of macular diseases
Takaki Sato1, Seita Morishita1, Taeko Horie1
1Department of Ophthalmology, Osaka Medical College, Takatsuki-City, Osaka, Japan.
Abstract:
We previously reported on the elevated intravitreal activities of tryptase and chymase in association with idiopathic epiretinal membrane (ERM) and idiopathic macular hole (MH). In this present study, we investigated the potential intraocular production of these serine proteases, and measured and compared tryptase and chymase activities in the vitreous body and serum in ERM, MH, proliferative diabetic retinopathy (PDR), and rhegmatogenous retinal detachment (RRD) patients. In addition, nuclear staining with hematoxylin and eosin (H&E) and mast-cell staining with toluidine blue were performed on samples of the vitreous core and bursa premacularis (BPM) of MH. We also performed immunostaining on the above two regions of vitreous samples for MH with anti-tryptase antibody, anti-chymase antibody, anti-podoplanin antibody, anti-lymphatic vessel endothelial hyaluronan receptor 1 (LYVE-1) antibody, and anti-fibroblast antibody. Moreover, we performed immunostaining with anti-tryptase antibody and anti-chymase antibody on ERMs collected intraoperatively. Tryptase activity in the vitreous body was significantly higher in ERM and MH than in PDR. However, no significant differences were observed in the tryptase activity in the serum among these four diseases. Chymase activity in the vitreous body was significantly higher in MH than in the other three diseases, yet chymase activity in the serum was below detection limit in any of the diseases. Nuclear staining with H&E revealed an abundance of nuclei in the BPM region, but few in the surrounding area. Mast-cell staining with toluidine blue revealed that the BPM showed metachromatic staining. In immunostaining with anti-fibroblasts antibody, anti-tryptase antibody, anti-chymase antibody, anti-podoplanin antibody, and anti-LYVE-1 antibody, the BPM stained more strongly than the vitreous core. Tryptase and chymase-positive cells were also observed in ERM. These findings revealed that the presence of mast cells in the BPM potentially represent the source of these serine proteases. Moreover, the BPM, as a lymphatic tissue, may play an important role in the pathogenesis of macular disease.
Insights
Mast cells in the bursa premacularis (BPM) may produce tryptase and chymase, contributing to epiretinal membrane (ERM) and macular hole (MH) pathogenesis. This suggests the BPM
Area of Science:
- Ophthalmology
- Cell Biology
- Pathology
Background:
- Previous studies indicated elevated intravitreal tryptase and chymase in idiopathic epiretinal membrane (ERM) and macular hole (MH).
- Serine proteases are implicated in various ocular pathologies, but their intraocular source and specific role in macular diseases require further investigation.
Purpose of the Study:
- To investigate the intraocular production of tryptase and chymase.
- To compare vitreous and serum levels of these enzymes in ERM, MH, proliferative diabetic retinopathy (PDR), and rhegmatogenous retinal detachment (RRD).
- To identify the cellular source of these proteases within the macula.
Main Methods:
- Measurement of tryptase and chymase activity in patient vitreous and serum samples.
- Histological analysis (H&E, toluidine blue) of vitreous core and bursa premacularis (BPM) in MH samples.
- Immunohistochemical staining for tryptase, chymase, podoplanin, LYVE-1, and fibroblasts in vitreous and ERM samples.
Main Results:
- Vitreous tryptase activity was significantly higher in ERM and MH compared to PDR.
- Vitreous chymase activity was significantly higher in MH than in other conditions; serum levels were undetectable.
- Bursa premacularis (BPM) showed abundant nuclei, mast cell presence (toluidine blue staining), and stronger staining for fibroblasts, tryptase, chymase, podoplanin, and LYVE-1 compared to the vitreous core. Tryptase and chymase-positive cells were also found in ERMs.
Conclusions:
- Mast cells within the bursa premacularis (BPM) are a likely source of intravitreal tryptase and chymase.
- The BPM, functioning as lymphatic tissue, may play a significant role in the pathogenesis of macular diseases like MH and ERM.
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