title: Nicotinic acetylcholine receptor α1 promotes calpain-1 activation and macrophage inflammation in hypercholesterolemic nephropathy.
abstract: The nicotinic acetylcholine receptor α1 (nAChRα1) was investigated as a potential proinflammatory molecule in the kidney, given a recent report that it is an alternative urokinase plasminogen activator (uPA) receptor, in addition to the classical receptor uPAR. Two animal models and in vitro monocyte studies were involved: (1) In an ApoE(-/-) mouse model of chronic kidney disease, glomerular-resident cells and monocytes/macrophages were identified as the primary cell types that express nAChRα1 during hypercholesterolemia/uninephrectomy-induced nephropathy. Silencing of the nAChRα1 gene for 4 months (6 months on Western diet) prevented the increases in renal monocyte chemoattractant protein-1 and osteopontin expression levels and F4/80+ macrophage infiltration compared with the nonsilenced mice. These changes were associated with significantly reduced transforming growth factor-β1 mRNA (50% decrease) and α smooth muscle actin-positive (αSMA+) myofibroblasts (90% decrease), better glomerular and tubular basement membranes (GBM/TBM) preservation (threefold less disintegration), and better renal function preservation (serum creatinine 40% lower) in the nAChRα1-silenced mice. The nAChRα1 silencing was also associated with significantly reduced renal tissue calcium deposition (78% decrease) and calpain-1 (but not calpain-2) activation (70% decrease). (2) The nAChRα1 was expressed in vitro by mouse monocyte cell line WEHI-274.1. The silencing of nAChRα1 significantly reduced both calpain-1 and -2 activities, and reduced the degradation of the calpain substrate talin. (3) To further explore the role of calpain-1 activity in hypercholesterolemic nephropathy, disease severities were compared in CAST(-/-)ApoE(-/-) (calpain overactive) mice and ApoE(-/-) mice fed with Western diet for 10 months (n=12). Macrophages were the main cell type of renal calpain-1 production in the model. The number of renal F4/80+ macrophages was 10-fold higher in the CAST(-/-)ApoE(-/-) mice (P<0.05), and was associated with a significantly higher level of αSMA+ cells, increased GBM/TBM destruction, and higher serum creatinine levels. Our studies suggest that the receptor nAChRα1 is an important regulator of calpain-1 activation and inflammation in the chronic hypercholesterolemic nephropathy. This new proinflammatory pathway may also be relevant to other disorders beyond hyperlipidemic nephropathy.
authors.affiliation: Division of Nephrology, Seattle Children's Hospital Research Institute, Department of Pediatrics, University of Washington, Seattle, WA 98101, USA. MD6GZ@yahoo.com
authors.forename: Guoqiang
authors.initials: G
authors.lastname: Zhang
authors.forename: Alison L
authors.initials: AL
authors.lastname: Thomas
authors.forename: Amanda L
authors.initials: AL
authors.lastname: Marshall
authors.forename: Kelly A
authors.initials: KA
authors.lastname: Kernan
authors.forename: Yanyuan
authors.initials: Y
authors.lastname: Su
authors.forename: Yi
authors.initials: Y
authors.lastname: Zheng
authors.forename: Jiro
authors.initials: J
authors.lastname: Takano
authors.forename: Takaomi C
authors.initials: TC
authors.lastname: Saido
authors.forename: Allison A
authors.initials: AA
authors.lastname: Eddy
mesh_terms: D000199:Actins / Q000235:genetics; D000818:Animals; D000943:Antigens, Differentiation / Q000378:metabolism; D001057:Apolipoproteins E / Q000235:genetics / Q000378:metabolism; D015152:Blotting, Northern; D015153:Blotting, Western; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism; D002154:Calpain / Q000378:metabolism*; D002460:Cell Line; D005260:Female; D006937:Hypercholesterolemia / Q000150:complications; D007249:Inflammation / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D007668:Kidney / Q000378:metabolism / Q000473:pathology; D007674:Kidney Diseases / Q000209:etiology / Q000235:genetics / Q000378:metabolism*; D008264:Macrophages / Q000378:metabolism* / Q000473:pathology; D008297:Male; D051379:Mice; D057507:Mice, 129 Strain; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009000:Monocytes / Q000378:metabolism; D009392:Nephrectomy / Q000009:adverse effects; D034622:RNA Interference; D011978:Receptors, Nicotinic / Q000235:genetics / Q000378:metabolism*; D053773:Transforming Growth Factor beta1 / Q000235:genetics
chemical_list: D000199:Actins; D000943:Antigens, Differentiation; D001057:Apolipoproteins E; C555576:CHRNA1 protein, mouse; D002135:Calcium-Binding Proteins; D011978:Receptors, Nicotinic; D053773:Transforming Growth Factor beta1; C036763:monocyte-macrophage differentiation antigen; C033668:calpastatin; D002154:Calpain; C112682:Capn1 protein, mouse