Bitumen products alter bax, bcl-2 and cytokeratin expression: an in vivo study of chronically exposed road pavers.
BACKGROUND
The skin of road pavers is chronically exposed to bitumen fumes, a mixture of volatile compounds and particles, containing several carcinogenic and non-carcinogenic polycyclic aromatic hydrocarbons. Bitumen fumes can alter cutaneous barrier integrity in various ways and induce skin diseases. The present study was devised to investigate the expression of apoptosis proteins (bax and bcl-2) and the cytokeratin pattern in skin specimens from road paving workers exposed to bitumen fumes using immunohistochemical techniques.


METHODS
Skin forearm punch biopsies from 16 occupationally exposed workers and an unexposed control group were processed for immunohistochemistry using a broad-spectrum anti-cytokeratin antibody and monoclonal antibodies for bax and bcl-2 immunostaining. Urinary 1-hydroxypyrene (1-OHP) was also determined.


RESULTS
Morphological specimen evaluation showed epidermal thinning of exposed skin and flattened dermal papillae. In sections from exposed subjects, grade 3 bax overexpression and cytokeratin immunoreaction was detected in all layers, while bcl-2 expression was downregulated (grade 1) and confined to the basal layer. There was a significant difference in 1-OHP values between road pavers and the control group (p < 0.05).


CONCLUSIONS
Overexpression of the cytokeratin pattern and bax and underexpression of bcl-2 in chronically bitumen-exposed skin suggest that bitumen fumes induce activation of apoptosis as a defense mechanism.
Loreto
Carla
C
Department of Anatomy, Diagnostic Pathology, Forensic Medicine, Hygiene and Public Health, University of Catania, Via S. Sofia 87, 95123 Catania, Italy. carla.loreto@unict.it
Rapisarda
Veneranda
V
Carnazza
Maria Luisa
ML
Musumeci
Giuseppe
G
D'Agata
Velia
V
Valentino
Matteo
M
Martinez
Giuseppe
G
D000328:Adult; D000393:Air Pollutants / Q000009:adverse effects*; D006801:Humans; D006838:Hydrocarbons / Q000009:adverse effects*; D007633:Keratins / Q000378:metabolism*; D008297:Male; D016273:Occupational Exposure / Q000009:adverse effects*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D011721:Pyrenes / Q000378:metabolism; D012867:Skin / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D051028:bcl-2-Associated X Protein / Q000378:metabolism*
D000393:Air Pollutants; C494826:BAX protein, human; D006838:Hydrocarbons; D019253:Proto-Oncogene Proteins c-bcl-2; D011721:Pyrenes; D051028:bcl-2-Associated X Protein; D007633:Keratins; C006647:asphalt; C033146:1-hydroxypyrene