Zonation of the drug-metabolizing enzyme cytochrome P450 3A in infant mice begins in pre-weaning period

Kupffer cells determine intrahepatic traffic of PEGylated liposomal doxorubicin

Intrahepatic accumulation dominates organ distribution for most nanomedicines. However, obscure intrahepatic fate largely hampers regulation on their in vivo performance. Herein, PEGylated liposomal doxorubicin is exploited to clarify the intrahepatic fate of both liposomes and the payload in male mice. Kupffer cells initiate and dominate intrahepatic capture of liposomal doxorubicin, following to deliver released doxorubicin to hepatocytes with zonated distribution along the lobule porto-central axis. Increasing Kupffer cells capture promotes doxorubicin accumulation in hepatocytes, revealing the Kupffer cells capture-payload release-hepatocytes accumulation scheme. In contrast, free doxorubicin is overlooked by Kupffer cells, instead quickly distributing into hepatocytes by directly crossing fenestrated liver sinusoid endothelium. Compared to free doxorubicin, liposomal doxorubicin exhibits sustained metabolism/excretion due to the extra capture-release process. This work unveils the pivotal role of Kupffer cells in intrahepatic traffic of PEGylated liposomal therapeutics, and quantitively describes the intrahepatic transport/distribution/elimination process, providing crucial information for guiding further development of nanomedicines.

Mouse Cyp2c expression and zonation structure in the liver begins in the early neonatal stage

In the adult liver, drug-metabolizing enzymes such as cytochrome P450 (CYP) efficiently metabolize drugs by forming an expression pattern called "Zonation" structure around central veins. However, most previous studies on CYPs have focused on the expression levels of CYP mRNA and proteins in the whole liver. In this study, we analyzed not only the expression levels of Cyp2c family mRNAs and proteins in mice during fetal liver development, but also the relationship with their localization. In the whole fetal liver, Cyp2c mRNA and protein were hardly expressed. On the other hand, zonation analysis results showed that only some cells around the central vein of the fetal liver expressed Cyp2c. In addition, the protein expression level of Cyp2c in the whole liver during the neonatal period starts from postnatal day (P) 7 in both males and females, while the zonation is weakly formed from P5. This study suggested that fetal liver cannot metabolize Cyp2c substrate drugs transferred from mother to fetus due to low expression of Cyp2c and unformed zonation. The expression level of Cyp2c protein in neonates was lower than that in adult liver, and the zonation structure was not clear, suggesting that drug metabolism was not sufficient. Furthermore, this study revealed that the expression level of Cyp2c does not correlate with the formation of zonation structures, because Cyp2c expression is found in hepatocytes near the central vein even in the fetal and neonatal stages, when Cyp2c protein expression is hardly detectable in the whole liver. This article is protected by copyright. All rights reserved.

Characterization of hepatic zonation in mice by mass-spectrometric and antibody-based proteomics approaches

Periportal and perivenous hepatocytes show zonal heterogeneity in metabolism and signaling. Here, hepatic zonation in mouse liver was analyzed by non-targeted mass spectrometry (MS) and by the antibody-based DigiWest technique, yielding a comprehensive overview of protein expression in periportal and perivenous hepatocytes. Targeted immunoaffinity-based proteomics were used to substantiate findings related to drug metabolism. 165 (MS) and 82 (DigiWest) zonated proteins were identified based on the selected criteria for statistical significance, including 7 (MS) and 43 (DigiWest) proteins not identified as zonated before. New zonated proteins especially comprised kinases and phosphatases related to growth factor-dependent signaling, with mainly periportal localization. Moreover, the mainly perivenous zonation of a large panel of cytochrome P450 enzymes was characterized. DigiWest data were shown to complement the MS results, substantially improving possibilities to bioinformatically identify zonated biological processes. Data mining revealed key regulators and pathways preferentially active in either periportal or perivenous hepatocytes, with β-catenin signaling and nuclear xeno-sensing receptors as the most prominent perivenous regulators, and several kinase- and G-protein-dependent signaling cascades active mainly in periportal hepatocytes. In summary, the present data substantially broaden our knowledge of hepatic zonation in mouse liver at the protein level.

Maternal and Fetal Pharmacokinetic Analysis of Cannabidiol during Pregnancy in Mice

Cannabidiol (CBD), a major component of cannabis, has various effects, such as antiemetic and anxiolytic activities, and has recently been marketed as a supplement. The number of people using CBD during pregnancy is increasing, and there are concerns about its effects on the fetus. In addition, the scientific evidence supporting the fetal safety of CBD use during pregnancy is insufficient. To investigate CBD transfer from the mother to the fetus, a single intravenous dose of CBD was administered to pregnant mice in this study, and fetal pharmacokinetics (distribution and elimination) was analyzed. The transfer of CBD from the maternal blood to the fetus was rapid, and the compound accumulated in the fetal brain, liver, and gastrointestinal tract. Conversely, little CBD was transferred from the mother to the amniotic fluid. We analyzed the pharmacokinetics of CBD using a two-compartment model and found that the maternal and fetal half-lives of CBD were approximately 5 and 2 hours, respectively. Furthermore, we performed a moment analysis of the pharmacokinetics of CBD, observing a mean residence time of less than 2 hours in both the mother and fetus. These results suggest that once-daily CBD intake during pregnancy is unlikely to result in CBD accumulation in the mother or fetus. SIGNIFICANCE STATEMENT: CBD is currently marketed as a supplement, and despite its increasing use during pregnancy, little information concerning its fetal effects has been reported. In the present study, CBD was administered to pregnant mice, and the pharmacokinetics in the fetus was investigated using a two-compartment model and moment analysis. The results of these analyses provide important information for estimating the risk to the fetus if CBD is mistakenly consumed during pregnancy.

Acetaminophen-Induced Liver Injury Alters Expression and Activities of Cytochrome P450 Enzymes in an Age-Dependent Manner in Mouse Liver

Drug-induced liver injury (DILI) is a global medical problem. The risk of DILI is often related to expression and activities of drug-metabolizing enzymes, especially cytochrome P450s (P450s). However, changes on expression and activities of P450s after DILI have not been determined. The aim of this study is to fill this knowledge gap. Acetaminophen (APAP) was used as a model drug to induce DILI in C57BL/6J mice at different ages of days 10 (infant), 22 (child), and 60 (adult). DILI was assessed by levels of alanine aminotransferase and aspartate aminotransferase in plasma with a confirmation by H&E staining on liver tissue sections. The expression of selected P450s at mRNA and protein levels was measured by real-time polymerase chain reaction and liquid chromatography-tandem mass spectrometry, respectively. The activities of these P450s were determined by the formation of metabolites from probe drugs for each P450 using ultraperformance liquid chromatography-quadrupole time of flight mass spectrometry. DILI was induced at mild to severe levels in a dose-dependent manner in 200, 300, and 400 mg/kg APAP-treated groups at child and adult ages, but not at the infant age. Significantly decreased expression at mRNA and protein levels as well as enzymatic activities of CYP2E1, 3A11, 1A2, and 2C29 were found at child and adult ages. Adult male mice were more susceptible to APAP-induced liver injury than female mice with more decreased expression of P450s. These results suggest that altered levels of P450s in livers severely injured by drugs may affect the therapeutic efficacy of drugs, which are metabolized by P450s, more particularly for males. SIGNIFICANCE STATEMENT: The current study in an animal model demonstrates that acetaminophen-induced liver injury results in decreased expression and enzyme activities of several examined drug-metabolizing cytochrome P450s (P450s). The extent of such decreases is correlated to the degree of liver injury severity. The generated data may be translated to human health for patients who have drug-induced liver injury with decreased capability to metabolize drugs by certain P450s.