Expression of allograft inflammatory factor 1 in tissues from patients with systemic sclerosis and in vitro differential expression of its isoforms in response to transforming growth factor beta.
OBJECTIVE
Allograft inflammatory factor 1 (AIF-1), a protein initially identified in chronically rejected rat cardiac allografts, is involved in the immune response and proliferative vasculopathy that occurs during allograft rejection. Three well-characterized isoforms of AIF-1 result from alternative messenger RNA (mRNA) splicing. We previously identified a strong association of systemic sclerosis (SSc) with a polymorphism in AIF-1 isoform 2. The purpose of this study was to investigate AIF-1 expression in affected tissues from patients with SSc and to examine the regulation of its isoforms by transforming growth factor beta (TGFbeta).


METHODS
AIF-1 in the skin and lung tissues of patients with SSc was analyzed by immunochemistry. AIF-1 isoform expression in response to TGFbeta and interferon-gamma stimulation was examined by quantitative polymerase chain reaction (PCR).


RESULTS
AIF-1 protein was present in affected vessels of the lung and skin lesions of patients with SSc. Quantitative PCR showed an average of 14-fold higher mRNA levels in affected SSc skin than in normal skin. Double-label immunofluorescence staining demonstrated that T cells, macrophages, and endothelial cells in affected tissues expressed AIF-1. Stimulation of peripheral blood mononuclear cells with TGFbeta caused a specific and significant increase in the expression of AIF-1 isoform 2 transcripts (P < 0.005), which was due to stabilization of AIF-1 isoform 2 mRNA.


CONCLUSIONS
These data suggest that AIF-1 plays an important role in the pathogenesis of SSc owing to its increased expression in affected tissues and to the specific stimulation of AIF-1 isoform 2 by TGFbeta.
Del Galdo
Francesco
F
Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.
Maul
Gerd G
GG
Jiménez
Sergio A
SA
Artlett
Carol M
CM
D002135:Calcium-Binding Proteins; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004338:Drug Combinations; D042783:Endothelial Cells / Q000378:metabolism / Q000473:pathology; D004730:Endothelium, Vascular / Q000378:metabolism / Q000473:pathology; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D019084:Fluorescent Antibody Technique, Indirect; D015870:Gene Expression; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology; D007963:Leukocytes, Mononuclear / Q000187:drug effects* / Q000378:metabolism; D008168:Lung / Q000378:metabolism / Q000473:pathology; D008264:Macrophages / Q000378:metabolism / Q000473:pathology; D008840:Microfilament Proteins; D009687:Nuclear Proteins; D020033:Protein Isoforms; D012323:RNA Processing, Post-Transcriptional; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012595:Scleroderma, Systemic / Q000378:metabolism* / Q000473:pathology; D012867:Skin / Q000378:metabolism / Q000473:pathology; D013601:T-Lymphocytes / Q000378:metabolism / Q000473:pathology; D016212:Transforming Growth Factor beta / Q000494:pharmacology*
C112986:AIF1 protein, human; D002135:Calcium-Binding Proteins; D004268:DNA-Binding Proteins; D004338:Drug Combinations; D008840:Microfilament Proteins; D009687:Nuclear Proteins; D020033:Protein Isoforms; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; D007371:Interferon-gamma