Intermedin protects against renal ischemia-reperfusion injury by inhibiting endoplasmic reticulum stress.
BACKGROUND
Intermedin (IMD) is a novel member of the calcitonin/calcitonin gene-related peptide family. Endoplasmic reticulum stress (ERS) has been implicated in the pathology of renal ischemia/reperfusion (IRI). In the present study, we investigated whether IMD could reduce ERS damage after renal ischemia.


METHODS
The kidneys of SD rats were subjected to 45 min of warm ischemia followed by 24 h of reperfusion. The hypoxia/reoxygenation(H/R) model in NRK-52E cells consisted of hypoxia for 1 h and reoxygenation for 2 h. IMD was over-expressed in vivo and in vitro using the vector pcDNA3.1-IMD. The serum creatinine concentration and lactate dehydrogenase (LDH) activity in the plasma were determined. Histologic examinations of renal tissues were performed with PAS staining. Real-time PCR and Western blotting were used to determine the mRNA and protein levels, respectively. Additionally, ER staining was used to detect the ERS response.


RESULTS
In the rat renal IRI model, we found that IMD gene transfer markedly improved renal function and pathology and decreased LDH activity and cell apoptosis compared with the kidneys that were transfected with the control plasmid. IMD significantly attenuated the ERS stress parameters compared with IRI group. Indeed, IMD down-regulated glucose-regulated protein 78 (GRP78), C/EBP homologous protein(CHOP), and caspase 12 protein and mRNA levels. Moreover, in the NRK-52E cell H/R model, IMD overexpression prevented the apoptosis induced by H/R. Furthermore, IMD ameliorated the ER structural changes and concomitantly decreased the levels of GRP78, CHOP and caspase-12.


CONCLUSIONS
This study revealed that IMD protects against renal IRI by suppressing ERS and ERS-related apoptosis.
Department of Microbiology and Immunology, Shanxi Medical University, Taiyuan, Shanxi, China. wangyanhongmail@126.com.
Yanhong
Y
Wang
Department of Microbiology and Immunology, Shanxi Medical University, Taiyuan, Shanxi, China. jihutian429@163.com.
Jihua
J
Tian
Department of Nephrology, Second Hospital of Shanxi Medical University, Taiyuan, Shanxi, China. qiaoxi7347@163.com.
Xi
X
Qiao
Department of Nephrology, Second Hospital of Shanxi Medical University, Taiyuan, Shanxi, China. kunle6609@163.com.
Xiaole
X
Su
Department of Microbiology and Immunology, Shanxi Medical University, Taiyuan, Shanxi, China. 285055160@qq.com.
Yang
Y
Mi
Department of Nephrology, Second Hospital of Shanxi Medical University, Taiyuan, Shanxi, China. zhangruijing_0105@163.com.
Ruijing
R
Zhang
Department of Nephrology, the Affiliated People's Hospital of Shanxi Medical University, Shanxi Provincial People's Hospital, Shanxi Kidney Disease Institute, No. 29 Shuang Ta East Street, Taiyuan, 030012, , Shanxi, P. R. China. rongshanli13@163.com.
Rongshan
R
Li
D053607:Adrenomedullin / Q000235:genetics* / Q000378:metabolism*; D000818:Animals; D017209:Apoptosis; D053454:Caspase 12 / Q000378:metabolism; D002460:Cell Line; D003404:Creatinine / Q000097:blood; D059865:Endoplasmic Reticulum Stress; D004847:Epithelial Cells; D015870:Gene Expression; D006360:Heat-Shock Proteins / Q000378:metabolism; D006836:Hydro-Lyases / Q000097:blood; D007684:Kidney Tubules / Q000166:cytology; D008297:Male; D009479:Neuropeptides / Q000235:genetics* / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015427:Reperfusion Injury / Q000097:blood / Q000473:pathology / Q000517:prevention & control*; D051742:Transcription Factor CHOP / Q000378:metabolism; D014162:Transfection; D015854:Up-Regulation / Q000235:genetics; D000091342:Endoplasmic Reticulum Chaperone BiP
D053607:Adrenomedullin; D053454:Caspase 12; D003404:Creatinine; D006360:Heat-Shock Proteins; D006836:Hydro-Lyases; D009479:Neuropeptides; D051742:Transcription Factor CHOP; C499411:Adm2 protein, rat; C497251:Ddit3 protein, rat; C051684:GRP78 protein, rat; D000091342:Endoplasmic Reticulum Chaperone BiP; C045581:lactate dehydratase