Mast cell chymase is a possible mediator of neurogenic bladder fibrosis.
OBJECTIVE
Urinary bladders of patients with myelomeningocele, owing to spina bifida, are often functionally impaired, fibrotic organs. Common to this condition are repeated occurrences of bladder infection and inflammation. Since mast cells have been associated with a fibrogenic response in inflammatory conditions, we investigated the role of mast cell granule product, chymase, as a mediator of myleodysplastic bladder fibrosis.


METHODS
Human control and myelodysplastic bladder tissues were stained with Unna's stain and chymase antibody to determine mast cell number and localization. Cell specific localization of collagen mRNAs was determined by in situ hybridization (ISH). In vitro, normal human bladder fibroblasts were treated with recombinant chymase, heparin and inhibitors, and collagen subtype concentration was determined by enzyme linked immunosorbent assay (ELISA).


RESULTS
Myelodysplastic bladders were characterized by increased mast cells in the detrusor muscle layer compared to control bladders, as well as mast cell degranulation and increased connective tissue deposition. Both types I and III collagen mRNA localized to fibroblasts surrounding detrusor muscle fascicles, whereas only collagen III mRNA localized to cells within connective tissue infiltrated muscle bundles in myelomeningocele bladder tissue. Chymase treatment of bladder fibroblasts, in vitro, was dose-dependent and resulted in significant increases in both types I and III collagen. Heparin did not alter collagen protein expression, whereas heparin-chymase combination modulated type III collagen expression. Serine protease inhibitor, phenylmethylsulfonlyfluoride, did not inhibit collagen synthesis, whereas denatured chymase resulted in decreased collagenous protein levels.


CONCLUSIONS
Bladder fibrosis may be mediated by mast cell chymase stimulation of collagen synthesis.
Howard
Pamela S
PS
Department of Anatomy & Cell Biology, University of Pennsylvania School of Dental Medicine, Philadelphia, Pennsylvannia 19104-6030, USA. howard@biochem.dental.upenn.edu
Renfrow
David
D
Schechter
Norman M
NM
Kucich
Umberto
U
D000293:Adolescent; D015550:Cell Degranulation; D002478:Cells, Cultured; D002648:Child; D002675:Child, Preschool; D053818:Chymases; D003094:Collagen / Q000378:metabolism; D024042:Collagen Type I / Q000235:genetics / Q000378:metabolism; D024061:Collagen Type III / Q000235:genetics / Q000378:metabolism; D003238:Connective Tissue / Q000378:metabolism / Q000473:pathology; D004305:Dose-Response Relationship, Drug; D005260:Female; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D005355:Fibrosis; D006801:Humans; D017403:In Situ Hybridization; D007223:Infant; D008297:Male; D008407:Mast Cells / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology; D008591:Meningomyelocele / Q000150:complications*; D010664:Phenylmethylsulfonyl Fluoride / Q000494:pharmacology; D011480:Protease Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D012697:Serine Endopeptidases / Q000008:administration & dosage / Q000378:metabolism*; D001743:Urinary Bladder / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology; D001750:Urinary Bladder, Neurogenic / Q000201:enzymology* / Q000209:etiology / Q000378:metabolism / Q000473:pathology*
D024042:Collagen Type I; D024061:Collagen Type III; D011480:Protease Inhibitors; D012333:RNA, Messenger; D010664:Phenylmethylsulfonyl Fluoride; D003094:Collagen; D012697:Serine Endopeptidases; D053818:Chymases