Increased chromosome damage in systemic sclerosis skin fibroblasts

Abstract

Objective: To evaluate chromosome damage, by means of micronucleus frequency, in dermal fibroblasts from affected and non-affected skin from systemic sclerosis (SSc) patients and from controls.

Methods: Primary fibroblast cultures were obtained by biopsy from affected and non-affected skin from SSc patients. Control fibroblasts were derived from skin remnants from plastic surgery in healthy adults. The number of micronuclei-bearing cells per 1000 binucleated cells (MN⁺ cells/1000 BN) was determined in cultures with and without clastogenic stimulus (bleomycin 3 μg/mL).

Results: Primary cultures from 10 SSc patients (affected and non-affected skin) and nine controls were analysed by two blinded examiners. In the absence of bleomycin, the frequency of MN⁺ cells was higher in cultures from affected (14.01 ± 11.96 MN⁺ cells/1000 BN; p = 0.004) and non-affected (15.41 ± 13.58 MN⁺ cells/1000 BN; p = 0.005) skin from SSc patients as compared to fibroblasts from healthy controls (4.74 ± 3.30 MN⁺ cells/1000 BN). In bleomycin-treated cultures, the frequency of MN⁺ cells was higher in SSc affected (38.03 ± 26.14 MN⁺ cells/1000 BN; p = 0.041) and non-affected skin (38.47 ± 17.88 MN⁺ cells/1000 BN; p = 0.034) as compared to healthy control fibroblasts (20.54 ± 13.09 MN⁺ cells/1000 BN). There was no difference in the frequency of MN⁺ cells in cultures from affected and non-affected skin of SSc patients.

Conclusions: This is the first demonstration that dermal fibroblasts from SSc patients present an increased frequency of spontaneous and clastogen-induced micronuclei. Increased clastogenesis seems to be a widespread phenomenon in SSc because fibroblasts from clinically affected and non-affected skin presented the equivalent increased micronuclei counts.

Acknowledgements

This study was supported by grant no. 04/00436-4 from the São Paulo Research Foundation FAPESP, and funds from the Brazilian Society of Rheumatology.