Organic anion-transporting polypeptide 2B1 knockout and humanized mice; insights into the handling of bilirubin and drugs

Organic anion transporting polypeptide 2B1 (OATP2B1/SLCO2B1) facilitates uptake transport of structurally diverse endogenous and exogenous compounds. To investigate the roles of OATP2B1 in physiology and pharmacology, we established and characterized Oatp2b1 knockout (single Slco2b1^-/- and combination Slco1a/1b/2b1^-/-) and humanized hepatic and intestinal OATP2B1 transgenic mouse models. While viable and fertile, these strains exhibited a modestly increased body weight. In males, unconjugated bilirubin levels were markedly reduced in Slco2b1^-/- compared to wild-type mice, whereas bilirubin monoglucuronide levels were modestly increased in Slco1a/1b/2b1^-/- compared to Slco1a/1b^-/- mice. Single Slco2b1^-/- mice showed no significant changes in oral pharmacokinetics of several tested drugs. However, markedly higher or lower plasma exposure of pravastatin and the erlotinib metabolite OSI-420, respectively, were found in Slco1a/1b/2b1^-/- compared to Slco1a/1b^-/- mice, while oral rosuvastatin and fluvastatin behaved similarly between the strains. In males, humanized OATP2B1 strains showed lower conjugated and unconjugated bilirubin levels than control Slco1a/1b/2b1-deficient mice. Moreover, hepatic expression of human OATP2B1 partially or completely rescued the impaired hepatic uptake of OSI-420, rosuvastatin, pravastatin, and fluvastatin in Slco1a/1b/2b1^-/- mice, establishing an important role in hepatic uptake. Expression of human OATP2B1 in the intestine was basolateral and markedly reduced the oral availability of rosuvastatin and pravastatin, but not of OSI-420 and fluvastatin. Neither lack of Oatp2b1, nor overexpression of human OATP2B1 had any effect on fexofenadine oral pharmacokinetics. While these mouse models still have limitations for human translation, with additional work we expect they will provide powerful tools to further understand the physiological and pharmacological roles of OATP2B1.

Effect of statins on the risk of recurrent venous thromboembolism: A systematic review and meta-analysis

BACKGROUND

Recent studies have suggested that statins may be associated with a lower risk of recurrent venous thromboembolism (VTE).

METHODS

We systematically searched PubMed, Web of Science and Cochrane Library from inception until May 2020 to identify any eligible studies that reported the association between statin use and the risk of recurrent VTE, and conducted a comprehensive systematic review and meta-analysis (PROSPERO registration number: CRD42020190169) on this matter.

RESULTS

A total of 14 observational studies were included for qualitative review and 12 of them qualified for meta-analyses. The main meta-analysis found that statin use was associated with a lower risk of disease recurrence among patients with VTE (pooled adjusted HR: 0.76, 95% CI: 0.69-0.83), which was robust in sensitivity analyses and free of significant publication bias. Additionally, such association was present when restricting to periods after anticoagulation withdrawal (pooled adjusted HR: 0.78, 95% CI: 0.70-0.88) and when separately analyzing recurrent deep vein thrombosis (pooled adjusted HR: 0.71, 95% CI: 0.62-0.81) and recurrent pulmonary embolism (pooled adjusted HR: 0.80, 95% CI: 0.66-0.97; P = 0.027). Furthermore, statin use in patients with VTE was also found to be associated with a lower risk of all-cause mortality (adjusted HR: 0.65, 95% CI: 0.56-0.77), and possibly an even lower risk of bleeding (adjusted HR: 0.88, 95% CI: 0.73-1.07), albeit not statistically significant.

CONCLUSION

Statins have the potential to reduce recurrent events among patient with VTE. Randomized clinical trials to better explore the effect of statins in secondary prevention of VTE are warranted.

Differential changes in the pharmacokinetics of statins in collagen-induced arthritis rats

The elevated systemic levels of cytokines in rheumatoid arthritis (RA) can change the expression of metabolic enzymes and transporters. Given that statins are lipid-lowering agents frequently used in RA patients with concurrent cardiovascular diseases, the objective of the present study was to investigate the impacts of RA on the pharmacokinetics of statins of different disposition properties in rats with collagen-induced arthritis (CIA). The expression of metabolic enzymes and transporters in tissues of CIA rats were analyzed by RT-qPCR. Statins were given to CIA rats and controls through different routes, respectively. Blood samples were collected and analyzed by UPLC/MS/MS. Isolated microsomes and hepatocytes were used to determine the metabolic and uptake clearance of statins. The results showed that, compared with controls, the mRNA levels of intestinal Cyp3a1 and hepatic Cyp2c6, Cyp2c7, Cyp3a1, Oatp1a1, Oatp1b2, Oatp1a4, and Mrp2 were markedly decreased in the CIA rats. The maximal metabolic activities of Cyp2c and Cyp3a were reduced in liver microsomes of CIA rats. When given orally or injected through hepatic portal vein, the systemic levels of fluvastatin, simvastatin, and atorvastatin, but not of rosuvastatin and pravastatin, were increased in CIA rats. The metabolic clearance of simvastatin and hepatic uptake clearance of fluvastatin and atorvastatin were decreased in CIA rats. These findings suggest that the changes in the expression of enzymes and/or transporters in CIA rats differentially affect the pharmacokinetics of statins.

Cyclooxygenase inhibition and rosuvastatin-induced vascular protection in the setting of ischemia-reperfusion: A human in vivo study

The 3-hydroxy-3-methylglutaryl coenzyme A (HMG Co-A) reductase inhibitors have preconditioning effects involving up-regulation of cyclooxygenase (COX)-2. We investigated the effect of selective and non-selective COX inhibition on rosuvastatin-mediated protection against ischemia-reperfusion (IR)-induced endothelial dysfunction in the human forearm. Healthy volunteers (n=66) were allocated to placebo, acetylsalicylic acid (ASA) 81mg daily, ASA 325mg daily, celecoxib 200mg twice daily or 400mg ibuprofen four times daily, each administered for 5 to 7days. On the last day of study drug therapy, subjects received a single dose of 40mg rosuvastatin. Twenty-four hours later flow-mediated dilation (FMD) of the radial artery was evaluated before and after IR. In the placebo group, FMD was similar before and after IR (8.1±1.0 vs 7.2±0.8%; P=NS) indicating a significant protective effect of rosuvastatin. There was also no effect of IR on FMD in the ASA 81mg group (6.7±0.6 vs 6.1±0.7%; P=NS). In contrast, following IR there was a significant decrease in FMD in the ASA 325mg group (7.2±0.8 vs 3.3±0.7%, P<0.001), the celecoxib group (7.3±1.5 vs 2.6±1.5%, P<0.01) as well as the ibuprofen group (6.8±0.7 vs 2.6±0.8%; P<0.01). Therefore, nonselective COX inhibition with ASA 325mg and ibuprofen completely inhibit the protective effects of rosuvastatin in the setting of IR injury, as does therapy with the specific COX-2 antagonist celecoxib. In contrast, therapy with low dose ASA (81mg daily) does not have such inhibitory effects.