Contrasting effects of steroids and mizoribine on macrophage activation and glomerular lesions in rat thy-1 mesangial proliferative glomerulonephritis.
BACKGROUND
Macrophages with a pro-inflammatory (M1) phenotype mediate renal injury in proliferative forms of glomerulonephritis, while alternatively activated (M2) macrophages are thought to be anti-inflammatory and promote repair. Glucocorticoids, the mainstay therapy for proliferative glomerulonephritis, can induce alternative macrophage activation in vitro, but it is unknown whether this occurs in vivo and if this is required for glucocorticoid responsiveness. In addition, clinical studies have suggested that the ability of mizoribine (MZR) to suppress steroid-resistant proliferative glomerulonephritis may operate via inhibiting pro-inflammatory macrophage activation.


METHODS
This study examined prednisolone (PSL) and/or MZR treatment of rat Thy-1 disease - a model in which macrophages promote mesangial proliferative glomerulonephritis.


RESULTS
PSL treatment of Thy-1 nephritis induced an M2-like macrophage phenotype, but failed to modify mesangial hypercellularity and actually exacerbated global glomerulosclerosis. In contrast, MZR treatment reduced hypercellularity and glomerulosclerosis and suppressing both M1 and M2 markers of macrophage activation, with a selective reduction in CD169+ macrophages. Combined PSL/MZR treatment suppressed glomerular lesions and prevented steroid induction of an M2-like macrophage phenotype. In vitro, MZR prevented steroid induction of an M2 macrophage phenotype.


CONCLUSIONS
Glucocorticoid induced alternative macrophage activation failed to ameliorate rat mesangial proliferative glomerulonephritis, whereas MZR suppression of this disease model was attributed, in part, to inhibition of M1-like pro-inflammatory macrophage activation.
Ikezumi
Yohei
Y
Department of Pediatrics, Niigata University Medical and Dental Hospital, Japan. ikezumi@med.niigata-u.ac.jp
Suzuki
Toshiaki
T
Karasawa
Tamaki
T
Hasegawa
Hiroya
H
Kawachi
Hiroshi
H
Nikolic-Paterson
David J
DJ
Uchiyama
Makoto
M
D000818:Animals; D015415:Biomarkers; D002478:Cells, Cultured; D005260:Female; D015870:Gene Expression / Q000276:immunology; D015432:Glomerulonephritis, Membranoproliferative / Q000188:drug therapy* / Q000276:immunology* / Q000473:pathology; D016130:Immunophenotyping; D007166:Immunosuppressive Agents / Q000494:pharmacology; D007678:Kidney Glomerulus / Q000187:drug effects / Q000276:immunology / Q000473:pathology; D017737:Macrophages, Peritoneal / Q000187:drug effects* / Q000276:immunology / Q000473:pathology; D011239:Prednisolone / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D012263:Ribonucleosides / Q000494:pharmacology*; D013256:Steroids / Q000494:pharmacology*; D018800:Thy-1 Antigens / Q000276:immunology
D015415:Biomarkers; D007166:Immunosuppressive Agents; D012263:Ribonucleosides; D013256:Steroids; D018800:Thy-1 Antigens; C010052:mizoribine; D011239:Prednisolone