Enhanced collagen synthesis and transcription by peak E, a contaminant of L-tryptophan preparations associated with the eosinophilia myalgia syndrome epidemic.
The pathogenesis of the eosinophilia myalgia syndrome (EMS) remains unclear. Several abnormal constituents have been found in the L-tryptophan lots responsible for the illness, particularly, 1,1-ethylidenebis[L-tryptophan], also called peak E or EBT, and 3-phenylamino-alanine or peak 5. However, the role of these contaminants in the pathogenesis of EMS and in the development of fibrosis is unknown. We now report that peak E, a dimer of L-tryptophan, is a potent stimulus for human dermal fibroblast DNA and collagen synthesis. Peak E (0.1-1.0 microM) increased DNA synthesis up to four-fold (P = 0.0001) in a dose-dependent manner (r = 0.987). When added to monolayer cultures for 2 to 24 h, peak E (0.5 to 100 microM) caused a progressive, more than threefold increase in alpha 1(I) procollagen mRNA levels and collagenous protein. No increase in procollagen mRNA levels was found after the addition of another major L-tryptophan contaminant, peak 5, or with L-tryptophan itself. Transient transfection with a 2.5-kb alpha 1(I) procollagen promoter-luciferase construct showed that peak E causes a twofold upregulation of promoter activity (P = 0.022). Contraction of collagen gels, consisting of human dermal fibroblasts incorporated into a type I collagen lattice, was enhanced two-fold by exposure to peak E (P = 0.001). We conclude that a major constituent of contaminated batches of L-tryptophan, peak E, is a potent stimulus for fibroblast activation and collagen synthesis. This stimulatory action of peak E may provide a direct mechanism for the development of fibrosis in EMS.
Takagi
H
H
University of Miami School of Medicine, Department of Dermatology and Cutaneous Surgery, Florida 33136, USA.
Ochoa
M S
MS
Zhou
L
L
Helfman
T
T
Murata
H
H
Falanga
V
V
D002478:Cells, Cultured; D003094:Collagen / Q000096:biosynthesis* / Q000235:genetics; D004261:DNA Replication / Q000187:drug effects; D004340:Drug Contamination; D016603:Eosinophilia-Myalgia Syndrome / Q000139:chemically induced / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D012867:Skin / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects; D014364:Tryptophan / Q000009:adverse effects*
D014364:Tryptophan; D003094:Collagen