Spontaneous cytokine gene expression by cultured skin fibroblasts of systemic sclerosis. Correlation with collagen synthesis.

OBJECTIVE: To investigate the spontaneous cytokine gene expression in fibroblasts from patients with diffuse cutaneous systemic sclerosis. Their pattern of expression was correlated with the production of collagen. METHODS: Fibroblasts were obtained from skin biopsies of nine patients diagnosed with systemic sclerosis (mean 16 +/- 8.7 years of disease duration) and ten control individuals. The cytokine gene expression was detected by coupled reverse transcriptase polymerase chain reaction for interleukins 1 beta, 6, 8, tumour necrosis factor-alpha, and transforming growth factor beta. In addition, collagen synthesis was measured by [14C]-proline uptake in fibroblast cultures. RESULTS: All fibroblast samples from patients expressed the interleukin-6 gene (p = 0.04 compared with controls). Eight of the nine patients expressed interleukin-8 (p = 0.02 compared with controls). Four of them expressed also transforming growth factor beta and two more weakly expressed the tumour necrosis factor-alpha gene. Only one patient showed transcription for the interleukin-1 beta gene. In accordance with such immune activation, collagen synthesis was higher in fibroblasts from patients with systemic sclerosis (p = 0.028) as compared with normal controls. Indeed, a positive correlation was found between the expression of IL-6 gene and collagen production (rs = 1). CONCLUSION: The constitutive expression of IL-6 and IL-8 genes by fibroblasts may play an important role in the perpetuation of local immune dysregulation, thus leading to a permanent fibroblast activation in patients with systemic sclerosis.

Contamination with Mycoplasma spp. induces interleukin-13 expression by human skin fibroblasts in culture.

The mycoplasmas comprise a discrete group of microorganisms that are known to exert a range of effects upon cells derived from the immune system. Some of these interactions turn out to be immunomodulatory, such as polyclonal stimulation of T and B cells or enhancement of the cytolytic potential of macrophages, NK cells and T lymphocytes. Immunologically committed cells, when infected with mycoplasmas, can also increase the production of cytokines (IL-1, IL-2, IL-4 and IL-6), interferon (IFN) gamma, tumor necrosis factor-alpha (TNF-alpha) and colony-stimulating factors (particularly GM-CSF). Moreover, mycoplasmas are potent inductors of cytokine secretion by fibroblasts in culture. Since growth factors are determinants for the activation and proliferation of immunocompetent cells in vitro, we decided to investigate if these effects are concordant with the finding of mycoplasma contamination. In order to address this question, we compared the pattern of lymphokine secretion by normal-derived human fibroblasts in culture with and without Mycoplasma spp. contamination. We found those human fibroblasts that have been contaminated with mycoplasma show production of IL-13 at the transcriptional level. This effect coincides with discrete morphological changes as compared to uncontaminated human fibroblasts. This is the first report to acknowledge that mycoplasma contamination can induce mRNA expression for IL-13 in cultured human fibroblasts.