Despite the global impact of macrophage activation in vascular disease, the underlying mechanisms remain obscure. Here we show, with global proteomic analysis of macrophage cell lines treated with either IFNγ or IL-4, that PARP9 and PARP14 regulate macrophage activation. In primary macrophages, PARP9 and PARP14 have opposing roles in macrophage activation. PARP14 silencing induces pro-inflammatory genes and STAT1 phosphorylation in M(IFNγ) cells, whereas it suppresses anti-inflammatory gene expression and STAT6 phosphorylation in M(IL-4) cells. PARP9 silencing suppresses pro-inflammatory genes and STAT1 phosphorylation in M(IFNγ) cells. PARP14 induces ADP-ribosylation of STAT1, which is suppressed by PARP9. Mutations at these ADP-ribosylation sites lead to increased phosphorylation. Network analysis links PARP9–PARP14 with human coronary artery disease. PARP14 deficiency in haematopoietic cells accelerates the development and inflammatory burden of acute and chronic arterial lesions in mice. These findings suggest that PARP9 and PARP14 cross-regulate macrophage activation.

Rationale Mitochondrial changes occur during cell differentiation and cardiovascular disease. Dynamin-related protein 1 (DRP1) is a key regulator of mitochondrial fission. We hypothesized that DRP1 plays a role in cardiovascular calcification, a process involving cell differentiation and a major clinical problem with high unmet needs. Objective To examine the effects of osteogenic promoting conditions on DRP1, and whether DRP1 inhibition alters the development of cardiovascular calcification. Methods and Results DRP1 was enriched in calcified regions of human carotid arteries, examined by immunohistochemistry. Osteogenic differentiation of primary human vascular smooth muscle cells (SMCs) increased DRP1 expression. DRP1 inhibition in human SMCs undergoing osteogenic differentiation attenuated matrix mineralization, cytoskeletal rearrangement, mitochondrial dysfunction, and reduced type 1 collagen secretion and alkaline phosphatase activity. DRP1 protein was observed in calcified human aortic valves, and DRP1 RNA interference reduced primary human valve interstitial cell calcification. Mice heterozygous for Drp1 deletion did not exhibit altered vascular pathology in a PCSK9 gain-of-function atherosclerosis model. However, when mineralization was induced via oxidative stress, DRP1 inhibition attenuated mouse and human SMC calcification. Femur bone density was unchanged in mice heterozygous for Drp1 deletion, and DRP1 inhibition attenuated oxidative stress-mediated dysfunction in human bone osteoblasts. Conclusions We demonstrate a new function of DRP1 in regulating collagen secretion and cardiovascular calcification, a novel area of exploration for the potential development of new therapies to modify cellular fibrocalcific response in cardiovascular diseases. Our data also support a role of mitochondrial dynamics in regulating oxidative stress-mediated arterial calcium accrual and bone loss.

1. Pitavastatin is a potent competitive inhibitor of HMG-CoA reductase little metabolized in hepatic microsomes. Pitavastatin lactone, which can be converted back to the unchanged form, is the major metabolite of pitavastatin in humans. To clarify the mechanism of the lactonization of pitavastatin and the metabolic properties of the lactone, we performed experiments in vitro. 2. On addition of UDP-glucuronic acid, human hepatic microsomes produced pitavastatin lactone and an unknown metabolite (UM-2). UM-2 was converted to its unchanged form by enzymatic hydrolysis and to a lactone form non-enzymatically. Using several human UGT-expressing microsomes, UGT1A3 and UGT2B7 were principally responsible for glucuronidation of pitavastatin leading to lactonization. 3. No marked difference in intrinsic clearance between pitavastatin and its lactone form was detected in human hepatic microsomes. 4. Pitavastatin lactone showed no inhibitory effects on CYP2C9- and CYP3A4-mediated metabolism of model substrates in contrast to other HMG-CoA reductase inhibitors. 5. The mechanism of pitavastatin lactone formation has been clarified, in that glucuronidation by UGT occurs first followed by lactonization via an elimination reaction. It was also found that pitavastatin lactone demonstrates no drug-drug interactions.

Summary:NK-104 is a new and very potent competitive inhibitor of HMG-CoA reductase. NK-104 bound to plasma protein of mouse, rat, rabbit, dog and monkey, at a binding ratio of more than 96%. NK 104 also highly bound to human serum albumin and a1 acid glycoprotein. However, no interaction in pro tein binding was found between NK-104 and selected highly protein binding drugs at their therapeutic con centrations in human plasma.The in vitro metabolism of 14C-NK 104 was investigated using the liver microsomes of rat, rabbit, guinea pig, dog, monkey and human. The radioactivity was mostly due to unchanged NK-104 except for monkey.A relatively large amount of M-13 (8-hydroxy NK-104) was observed in monkey, but not in other animal species. The kinetic study of NK 104 metabolism suggested that M-13 was formed with relatively low in trinsic clearance. Based on three different in vitro approaches, namely 1) chemical inhibition, 2) immunoin hibition and 3) metabolism by recombinant human P450, it is concluded that CYP2C9 and CYP2C8 are the enzymes responsible for the metabolism of NK-104. In addition, no inhibitory effect on CYP mediated 4-hy droxylation of tolbutamide (CYP2C9) in the presence of NK-104 was detected.In conclusion, NK-104 was highly bound to plasma protein whereas no mutual interaction in protein bind ing was found between NK-104 and various commonly used drugs. Furthermore, NK-104 was scarcely metabolized in the liver microsomes, and no drug/drug interaction between NK-104 and tolbutamide was noted in in vitro metabolism.

Pitavastatin is a potent competitive inhibitor of HMG-CoA reductase. In the current study, to elucidate the hepatobiliary excretion of pitavastatin, we investigated the plasma concentration and biliary excretion of (14)C-pitavastatin in EHBR. We also evaluated the distribution of pitavastatin in mdr1a/b knockout mice by whole body autoradiography and quantitative radioassay. In view of the widespread clinical use of pitavastatin and the importance of drug-drug interaction, the inhibitory effect on Pgp-mediated activation of ATPase was also investigated. No marked difference was observed in the plasma concentration and biliary excretion of radioactivity between SDR and EHBR after dosing of (14)C-pitavastatin. Little radioactive transfer into the brain was detected in mdr1a/b knockout mice and the ATPase activity of human Pgp was negligible in the presence of pitavastatin. Moreover, no inhibitory effect on the Pgp-mediated activation of ATPase by verapamil was found in the presence of pitavastatin over a wide concentration range. These results indicated that a cMOAT and Pgp-mediated transport mechanism did not play a major role in the distribution of pitavastatin.