Mesangial cell Fas ligand: upregulation in human lupus nephritis and NF-kappaB-mediated expression in cultured human mesangial cells.
BACKGROUND
Fas ligand (FasL) is a well-known death factor; however, the role of FasL in the regulation of human glomerulonephritis remains unclear.


METHODS
We investigated the renal expression and localization of FasL in various forms of human glomerulonephritis by immunohistochemistry, utilizing confocal laser scanning microscopy. We further evaluated cytokine-induced FasL expression via nuclear factor (NF)kappaB in cultured human mesangial cells (HMC). The level of soluble FasL was measured by a specific enzyme-linked immunosorbent assay (ELISA).


RESULTS
The frequency of glomerular FasL-positive cases was higher in lupus nephritis (37.9%) as compared with other forms of glomerulonephritis (8.7%). The glomerular FasL score in proliferative lupus nephritis was significantly higher than that in nonproliferative forms. Patients with a high apoptosis score, severe microhematuria, proteinuria, or decreased renal function had a high FasL score. Double immunolabelling demonstrated that the most prevalent phenotypes of FasL-positive cells were mesangial cells. In cultured HMC, interleukin (IL)1beta, lipopolysaccharide (LPS), or gamma interferon (IFN) upregulated membrane-bound FasL. IL1beta significantly, and LPS or gammaIFN weakly activated NFkappaB, but none of these agents activated NFkappaB/Rel-related nuclear factor of activated T cells (NFATc) or IFN regulatory factor-1. IL1beta-mediated NFkappaB was completely inhibited in the presence of lactacystin, a potent inhibitor of NFkappaB. Lactacystin-mediated inhibition of NFkappaB reduced FasL protein levels. Matrix metalloproteinase (MMP)-7, but not other MMPs (1, 2, 3, 8, or 9), significantly sensitized HMC to release soluble FasL after IL1beta stimulation.


CONCLUSIONS
The results suggest that: (1) upregulation of mesangial FasL may contribute to the glomerular inflammation in proliferative lupus nephritis in vivo; (2) proinflammatory cytokines, in particular IL1beta, produced in nephritis can upregulate FasL via the transcription factor NFkappaB in HMC; and (3) MMP-7-mediated release of soluble FasL could control the mesangial inflammation.
Department of Medicine and Clinical Science, Okayama University Graduate School of Medicine and Dentistry, 2-5-1 Shikata-cho, Okayama 700-8558, Japan.
Tomoko
T
Tsukinoki
Hitoshi
H
Sugiyama
Reiko
R
Sunami
Mizuho
M
Kobayashi
Tetsuya
T
Onoda
Yohei
Y
Maeshima
Yasushi
Y
Yamasaki
Hirofumi
H
Makino
D000111:Acetylcysteine / Q000031:analogs & derivatives* / Q000494:pharmacology; D002478:Cells, Cultured; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D016207:Cytokines / Q000494:pharmacology; D018450:Disease Progression; D024202:Electrophoretic Mobility Shift Assay; D004797:Enzyme-Linked Immunosorbent Assay; D053222:Fas Ligand Protein; D005920:Glomerular Mesangium / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D007202:Indicators and Reagents; D018836:Inflammation Mediators / Q000494:pharmacology; D007375:Interleukin-1 / Q000494:pharmacology; D008181:Lupus Nephritis / Q000378:metabolism*; D020783:Matrix Metalloproteinase 7 / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000096:biosynthesis*; D018613:Microscopy, Confocal; D008854:Microscopy, Electron; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000502:physiology*; D009687:Nuclear Proteins / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects
D015853:Cysteine Proteinase Inhibitors; D016207:Cytokines; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D007202:Indicators and Reagents; D018836:Inflammation Mediators; D007375:Interleukin-1; D008562:Membrane Glycoproteins; D016328:NF-kappa B; D009687:Nuclear Proteins; C067713:lactacystin; D020783:Matrix Metalloproteinase 7; D000111:Acetylcysteine