Alkaline phosphatase: a novel treatment target for cardiovascular disease in CKD

Abstract

Cardiovascular disease is the main cause of early death in the settings of chronic kidney disease (CKD), type 2 diabetes mellitus (T2DM), and ageing. Cardiovascular events can be caused by an imbalance between promoters and inhibitors of mineralization, which leads to vascular calcification. This process is akin to skeletal mineralization, which is carefully regulated and in which isozymes of alkaline phosphatase (ALP) have a crucial role. Four genes encode ALP isozymes in humans. Intestinal, placental and germ cell ALPs are tissue-specific, whereas the tissue-nonspecific isozyme of ALP (TNALP) is present in several tissues, including bone, liver and kidney. TNALP has a pivotal role in bone calcification. Experimental overexpression of TNALP in the vasculature is sufficient to induce vascular calcification, cardiac hypertrophy and premature death, mimicking the cardiovascular phenotype often found in CKD and T2DM. Intestinal ALP contributes to the gut mucosal defence and intestinal and liver ALPs might contribute to the acute inflammatory response to endogenous or pathogenic stimuli. Here we review novel mechanisms that link ALP to vascular calcification, inflammation, and endothelial dysfunction in kidney and cardiovascular diseases. We also discuss new drugs that target ALP, which have the potential to improve cardiovascular outcomes without inhibiting skeletal mineralization.

Apabetalone Mediated Epigenetic Modulation is Associated with Favorable Kidney Function and Alkaline Phosphatase Profile in Patients with Chronic Kidney Disease

“…ALP catalyzes the breakdown of inorganic pyrophosphate, which functions as an important inhibitor of calcification and mineralization [12]. Expressed by vascular smooth muscle cells, ALP has been previously associated with vascular calcification [13]. Higher ALP levels are correlated with increased risk of cardiovascular disease, calcification, and mortality in populations with and without CKD [14-16].…”

Assessing Calcification Onset in Aortic Valve Interstitial Cells

“…Two isoforms of TNALP exist: bone-specific TNALP and liver-specific TNALP, both of which are abundantly found in the serum [10]. Within the context of vascular calcification, bone TNALP is highly expressed in calcifying vascular smooth muscle cells and is likely to be responsible for calcium deposition and AVS pathogenesis [10].…”

“…One of these enzymes, alkaline phosphatase (ALP), is a metalloenzyme that has been shown to play a profound role in calcification onset by concentrating calcium [8], mineralizing hydroxyapatite crystals [8], and inactivating inhibitory polyphosphates [9]. In humans, there are four ALP isozymes: alkaline phosphatase, tissue-nonspecific isozyme (TNALP), intestinal-type alkaline phosphatase, placental-type alkaline phosphatase, and placental-like alkaline phosphatase [10]. Two isoforms of TNALP exist: bone-specific TNALP and liver-specific TNALP, both of which are abundantly found in the serum [10].…”

“…In humans, there are four ALP isozymes: alkaline phosphatase, tissue-nonspecific isozyme (TNALP), intestinal-type alkaline phosphatase, placental-type alkaline phosphatase, and placental-like alkaline phosphatase [10]. Two isoforms of TNALP exist: bone-specific TNALP and liver-specific TNALP, both of which are abundantly found in the serum [10]. Within the context of vascular calcification, bone TNALP is highly expressed in calcifying vascular smooth muscle cells and is likely to be responsible for calcium deposition and AVS pathogenesis [10].…”

“…Two isoforms of TNALP exist: bone-specific TNALP and liver-specific TNALP, both of which are abundantly found in the serum [10]. Within the context of vascular calcification, bone TNALP is highly expressed in calcifying vascular smooth muscle cells and is likely to be responsible for calcium deposition and AVS pathogenesis [10].A multitude of studies draw conclusions regarding the pathogenesis of AVS in humans by utilizing aortic valve interstitial cells from bovine [11][12][13]. The ultimate goal of these studies is to identify mechanisms that will help us better understand calcification onset in humans.…”