Production of Acetylcholine by Podocytes and its Protection from Kidney Injury in GN

KEY POINTS: Our study demonstrated the sole enzyme responsible for acetylcholine production, choline acetyltransferase, was expressed in podocytes. Acetylcholine decreased glomerular injury in GN by reducing inflammation and protecting endothelium. Choline acetyltransferase/acetylcholine production was induced in podocytes with drugs already available.

BACKGROUND: One of the most important factors modulating endothelial health is acetylcholine; and while it is associated as a cholinergic neurotransmitter, it is also expressed by non-neuronal cells. However, its role in the kidney, which does not receive cholinergic innervation, remains unknown.

METHODS: To determine whether acetylcholine is produced in the kidney, we used choline acetyltransferase (ChAT) (BAC)–enhanced green fluorescent protein (ChAT mice) transgenic mice in which enhanced green fluorescent protein is expressed under the control of the endogenous ChAT transcriptional regulatory elements. We then investigated the role of acetylcholine in kidney disease by inducing antiglomerular basement membrane GN (anti-GBM GN) in ChAT transgenic mice.

RESULTS: We demonstrate ChAT, the sole enzyme responsible for acetylcholine production, was expressed in glomerular podocytes and produced acetylcholine. We also show during anti-GBM GN in ChAT transgenic mice, ChAT expression was induced in the glomeruli, mainly in podocytes, and protects mice from kidney injury with marked reduction of glomerular proliferation/fibrinoid necrosis (by 71%), crescent formation (by 98%), and tubular injury (by 78%). By contrast, specific knockout of podocyte ChAT worsened the severity of the disease. The mechanism of protection included reduction of inflammation, attenuation of angiogenic factors reduction, and increase of endothelial nitric oxide synthase expression. In vitro and in vivo studies demonstrated available drugs such as cholinesterase inhibitors and ChAT inducers increased the expression of podocyte-ChAT and acetylcholine production.

CONCLUSIONS: These findings suggest de novo synthesis of acetylcholine by podocytes protected against inflammation and glomerular endothelium damage in anti-GBM GN.

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