Increased production of interleukin 6 and interleukin 8 in scleroderma fibroblasts.

OBJECTIVE

To determine additional abnormal characteristics related to cytokines in fibroblasts derived from systemic sclerosis (SSc), we examined the production of interleukin 6 (IL-6) and IL-8 and their mRNA levels both in scleroderma fibroblasts and in those from normal skin.

METHODS

Cultured fibroblasts from patients with SSc and healthy controls were examined. Production of IL-6 and IL-8 was assessed by specific ELISA, and the levels of IL-6 and IL-8 mRNA were determined by reverse transcriptase polymerase chain reaction (RT-PCR).

RESULTS

Basal production of both IL-6 and IL-8 was significantly increased in scleroderma fibroblasts compared with controls. When cells were stimulated with either IL-1beta (50 pg/ml) or tumor necrosis factor-alpha (TNF-alpha: 10 ng/ml), the production of IL-6 and IL-8 was predominantly increased in both cell strains and there was no significant difference in the production of IL-6 and IL-8 between them. When normal fibroblasts were stimulated with IL-1beta for 48 h and subcultured, both IL-6 and IL-8 production were significantly increased, and production remained elevated even after 3 passages. RT-PCR revealed that IL-6 and IL-8 mRNA were detected in scleroderma fibroblasts but not in normal skin fibroblasts without cytokine stimulation. When stimulated with IL-1beta, both cell strains expressed IL-6 and IL-8 mRNA to almost the same extent.

CONCLUSION

Increased production of IL-6 and IL-8 by scleroderma fibroblasts suggests that these cells may have been stimulated by certain cytokines in vivo.