Autocrine activation by interleukin 1alpha induces the fibrogenic phenotype of systemic sclerosis fibroblasts.
OBJECTIVE
To explore the cellular localization of interleukin 1alpha (IL-1alpha) in cultured fibroblasts from lesional skin of patients with systemic sclerosis (SSc) and to study the role of intracellular IL-1alpha in the activation of fibroblasts.


METHODS
Dermal fibroblasts were derived from 12 patients with SSc. Expression of IL-1alpha mRNA was examined using reverse transcriptase-polymerase chain reaction (RT-PCR). The cellular distribution of IL-1alpha was examined by subcellular fractionation, flow cytometry, and immunocytochemistry. A full-length IL-1alpha cDNA was subcloned into the pcDNA3 vector to create sense and antisense-encoding constructs. Normal and SSc fibroblasts were stably transfected with the sense and antisense-encoding constructs, respectively. Stably transfected fibroblast clones were analyzed for the production of procollagen and IL-6 protein by ELISA, alpha1(I) procollagen mRNA by Northern blot hybridization, and proliferation by [3H]thymidine incorporation.


RESULTS
SSc-affected fibroblasts constitutively expressed intracellular IL-1alpha, which was predominantly located in the nucleus. Inhibition of IL-1alpha expression in SSc-affected fibroblasts using antisense constructs resulted in decreased proliferation, IL-6 production, and procollagen synthesis. Conversely, overexpression of IL-1alpha in normal fibroblasts resulted in development of the SSc fibroblast phenotype.


CONCLUSIONS
IL-1alpha is an important autocrine fibrogenic factor in SSc, suggesting that inhibition of intracellular IL-1alpha may be a novel strategy for the treatment of SSc.
Division of Rheumatology and Clinical Immunology, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.
Yasushi
Y
Kawaguchi
Susan A
SA
McCarthy
Simon C
SC
Watkins
Timothy M
TM
Wright
D019898:Autocrine Communication; D049109:Cell Proliferation; D002478:Cells, Cultured; D005347:Fibroblasts / Q000166:cytology / Q000502:physiology*; D005355:Fibrosis; D006801:Humans; D007375:Interleukin-1 / Q000235:genetics / Q000378:metabolism*; D015850:Interleukin-6 / Q000378:metabolism; D016376:Oligonucleotides, Antisense / Q000235:genetics / Q000378:metabolism; D010641:Phenotype; D011347:Procollagen / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D012595:Scleroderma, Systemic / Q000276:immunology* / Q000473:pathology*; D013347:Subcellular Fractions / Q000378:metabolism
D007375:Interleukin-1; D015850:Interleukin-6; D016376:Oligonucleotides, Antisense; D011347:Procollagen; D012333:RNA, Messenger