Human mast cells activate fibroblasts: tryptase is a fibrogenic factor stimulating collagen messenger ribonucleic acid synthesis and fibroblast chemotaxis.
The effect of human mast cells on fibroblast activity was studied using an organotypic skin-equivalent culture system. Human mast cell-1 (HMC-1) cells were embedded in a collagen gel with neonatal dermal fibroblasts at a ratio of 1:4; keratinocytes then were allowed to stratify above this composite culture. Analysis of type a1(I) procollagen mRNA synthesis by in situ hybridization revealed a substantial increase in mRNA levels in the presence of mast cells and especially following degranulation, induced by calcium ionophore A23187. Tryptase, a major product of human mast cells, could substitute for mast cells in this culture system, up-regulating procollagen mRNA synthesis. Tryptase pretreated with the specific protease inhibitor bis(5-amidino-2-benzimidazo-lyl)methane (BABIM) markedly attenuated the collagen mRNA up-regulation. Further studies revealed HMC-1 cell sonicates stimulated fibroblast chemotaxis and procollagen mRNA synthesis. Inhibition of HMC-1 sonicates with either BABIM or a neutralizing mAb against tryptase resulted in significant reduction of fibroblast chemotaxis and procollagen mRNA, implying that tryptase accounted for the majority of HMC-1 sonicate activity. Tryptase directly stimulated fibroblast chemotaxis with optimal concentrations between 10 pM and 1 nM. The maximal response of optimal concentrations of tryptase was comparable with the known fibrogenic factor, TGF-beta. Inhibition of tryptase with BABIM resulted in approximately 50% reduction in chemotactic activity. Additional studies revealed that tryptase (0.3-3 nM) stimulated procollagen mRNA synthesis in confluent monolayers of dermal fibroblasts.
Gruber
B L
BL
Department of Medicine and Dermatology, State University of New York at Stony Brook 11794, USA.
Kew
R R
RR
Jelaska
A
A
Marchese
M J
MJ
Garlick
J
J
Ren
S
S
Schwartz
L B
LB
Korn
J H
JH
D000328:Adult; D002460:Cell Line; D002633:Chemotaxis / Q000187:drug effects*; D053818:Chymases; D018920:Coculture Techniques; D003094:Collagen / Q000096:biosynthesis / Q000235:genetics*; D005347:Fibroblasts / Q000187:drug effects / Q000201:enzymology* / Q000276:immunology*; D006801:Humans; D017403:In Situ Hybridization; D008407:Mast Cells / Q000276:immunology*; D009924:Organ Culture Techniques; D012333:RNA, Messenger / Q000096:biosynthesis*; D012697:Serine Endopeptidases / Q000502:physiology*; D012867:Skin / Q000166:cytology; D053802:Tryptases
D012333:RNA, Messenger; D003094:Collagen; D012697:Serine Endopeptidases; C083294:chymase 2; D053818:Chymases; D053802:Tryptases