Tumor necrosis factor and interferon-gamma down-regulate Klotho in mice with colitis.
OBJECTIVE
Klotho (KL) is an anti-inflammatory protein that protects the endothelium from nitric oxide (NO)-induced dysfunction, reduces the expression of endothelial adhesion molecules, and potentially regulates T-cell functions. KL deficiency leads to premature senescence and impaired Ca2+/Pi homeostasis, which can lead to inflammatory bowel disease (IBD)-associated osteopenia/osteoporosis. We investigated the changes in renal expression of Kl as a consequence of colitis.


METHODS
We studied 3 mouse models of IBD: colitis induced by trinitrobenzene sulfonic acid, colitis induced by microflora (in gnotobiotic interleukin-10(-/-)), and colitis induced by adoptive transfer of CD4(+)CD45RB(high) T cells. Effects of the tumor necrosis factor (TNF) and interferon (IFN)-gamma on Kl expression and the activity of its promoter were examined in renal epithelial cells (mpkDCT4 and mIMCD3).


RESULTS
Renal expression of Kl messenger RNA (mRNA) and protein was reduced in all 3 models of IBD. Reduced level of KL correlated with the severity of colitis; the effect was reversed by neutralizing antibodies against TNF. In vitro, TNF inhibited Kl expression, an effect potentiated by IFN-gamma. The combination of TNF and IFN-gamma increased expression of inducible nitric oxide synthase (iNOS) and increased NO production. The effect of IFN-gamma was reproduced by exposure to an NO donor and reversed by the iNOS inhibitor. In cells incubated with TNF and/or IFN-gamma, Kl mRNA stability was unaffected, whereas Kl promoter activity was reduced, indicating that these cytokines regulate Kl at the transcriptional level.


CONCLUSIONS
The down-regulation of KL that occurs during inflammation might account for the extraintestinal complications such as abnormalities in bone homeostasis that occur in patients with IBD.
Thurston
Robert D
RD
Department of Pediatrics, Steele Children's Research Center, University of Arizona Health Sciences Center, Tucson, Arizona 85724, USA.
Larmonier
Claire B
CB
Majewski
Pawel M
PM
Ramalingam
Rajalakshmy
R
Midura-Kiela
Monica
M
Laubitz
Daniel
D
Vandewalle
Alain
A
Besselsen
David G
DG
Mühlbauer
Marcus
M
Jobin
Christian
C
Kiela
Pawel R
PR
Ghishan
Fayez K
FK
D019264:Adoptive Transfer; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D003092:Colitis / Q000378:metabolism*; D004195:Disease Models, Animal; D005966:Glucuronidase / Q000037:antagonists & inhibitors* / Q000235:genetics; D015212:Inflammatory Bowel Diseases / Q000150:complications / Q000378:metabolism; D007371:Interferon-gamma / Q000494:pharmacology*; D016753:Interleukin-10 / Q000502:physiology; D048031:JNK Mitogen-Activated Protein Kinases / Q000502:physiology; D007668:Kidney / Q000378:metabolism; D000090265:Klotho Proteins; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D009569:Nitric Oxide / Q000502:physiology; D010024:Osteoporosis / Q000209:etiology; D014158:Transcription, Genetic / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D014409:Tumor Necrosis Factor-alpha; D016753:Interleukin-10; D009569:Nitric Oxide; D007371:Interferon-gamma; D048031:JNK Mitogen-Activated Protein Kinases; D005966:Glucuronidase; D000090265:Klotho Proteins; D002118:Calcium