Clarifying the cytochrome P450s (CYPs) changes in non-alcoholic fatty liver disease (NAFLD) is important for optimizing drug therapy. This study compared the expression of CYP isoforms in rat models of nonalcoholic fatty liver (NAFL) and non-alcoholic steatohepatitis (NASH). An NAFL model without tissue damage or inflammation was established by feeding rats a high-fat diet (HFD) for a relatively short period of 4 weeks. Feeding rats with a methionine-choline-deficient diet (MCDD) for 4 weeks produced steatohepatitis-like NASH. Here, the mRNA and protein expression levels of several CYP enzymes in NAFL and NASH models were compared with those in rats fed a control diet (CD). CYP1A2 expression and activity were upregulated in the NAFL model and downregulated in the NASH model, suggesting a reversal of CYP1A2 expression between NAFL and NASH. Differential expression of CYP1A2 in the NAFL and NASH models was observed in primary rat hepatocytes. These findings suggest that CYP1A2 expression/activity vary from the early stages of NAFL to NASH and that monitoring the pharmacokinetics of CYP1A2-metabolized drugs in humans with NAFL and NASH is necessary.

Various nanomaterials are used as food additives, medicines, and cosmetics; however, their biological effects are not completely understood. Since the cell membrane is the first point of contact between nanomaterials and cells, we investigated whether amorphous silica particles and titanium dioxide nanoparticles (nTiO₂) interact with the transporters present in the cell membrane. In this study, we prepared an adriamycin (ADM) resistant variant of the mouse lymphocytic leukemia cell line L1210 (L1210/ADM). Since our L1210/ADM cells were confirmed to excrete ADM in a P-glycoprotein (P-gp)-dependent manner, we investigated whether nano- and micro-sized amorphous silica particles (nSP and mSP) and nTiO₂ inhibited ADM excretion from L1210/ADM cells. Both nSP and nTiO₂ inhibited ADM efflux in a dose-dependent manner; however, mSP did not inhibit ADM efflux even at the highest dose (0.25 mg/mL). These results suggest that nSP and nTiO₂ interfere with P-gp, which is involved in ADM transport, and L1210/ADM cells are suitable for safety screening tests of nanomaterials.

In contrast with standard systemic drugs, the toxicity study of ophthalmic drug has unique design and packaging characteristics. The present survey aimed to characterize the nonclinical toxicological strategy of intravitreal administration (IVT) drugs by summarizing the toxicity study packages and comparing toxicity findings with clinical side effects. Safety pharmacology studies, toxicity studies, and clinical adverse reactions of the following seven IVT drugs were surveyed: pegaptanib sodium, ranibizumab, aflibercept, brolucizumab, faricimab, triamcinolone acetonide, and ranibizumab biosimilar. The toxicity study packages for IVT drugs were constructed according to ICH guidelines, although there were several differences between the modalities, application categories, and drugs. The characteristics of toxicity study packages include the fact that many safety pharmacology and acute toxicity endpoints need not be conducted as separate studies owing to the low systemic exposure. In addition, local toxicity findings (especially intraocular inflammation) require caution due to the relatively invasive administration method necessitates, and monkeys were mainly used as animal species in the IVT studies. Notably, certain drugs were found to have the severe adverse reactions of retinal vascular lesions, probably owing to immunoreaction. Importantly, these immunoreaction-related adverse reactions were not detected in these nonclinical toxicity studies. Therefore, risk assessments using toxicity studies, immunogenicity, and host impurities are important for the prediction and control of adverse reactions. This survey provides valuable information for the construction of a toxicity study design for IVT drug development.

Proliferating cells, such as tumor cells, require nucleotides for DNA replication. Mammalian cells are equipped with de novo purine and pyrimidine nucleotide biosynthesis pathways, and a salvage pathway that recycles purine bases, to supply nucleotides for the same. To avoid imbalance in intracellular nucleotide levels, de novo nucleotide biosynthesis pathway is regulated by feedback mechanisms, such as synthase inhibition by nucleotide products. Recently, we reported that the aldehyde dehydrogenase 1 family member L1 (ALDH1L1) consumes 10-formyltetrahydrofolate (10-fTHF), which is utilized by the de novo purine nucleotide synthesis, and results in the accumulation of 5-aminoimidazole-4-carboxamide ribonucleotide (ZMP) during purine biosynthesis. Given that ZMP inhibits pyrimidine nucleotide synthesis, in the present study, we examined the effects of ZMP using brequinar, a dihydroorotate dehydrogenase inhibitor. ALDH1L1-mediated ZMP accumulation was unaffected by brequinar, and no effect was observed when brequinar was combined with 5-aminoimidazole-4-carboxamide riboside (AICAr), a nucleoside of ZMP. Furthermore, we examined involvement in the salvage pathway, because attenuation of de novo purine nucleotide synthesis may require a supply of purine nucleotides from the salvage pathway. The guanine analog, 6-thioguanine, and the 2'-deoxycytidine analog, cytarabine, were used in the assessment of dependency on the salvage pathway. We found that neither ALDH1L1-mediated ZMP accumulation nor the presence of AICAr affected the salvage pathway. Collectively, these results suggest that these purine and pyrimidine analogs can be useful for the treatment of tumor cells, regardless of ALDH1L1 expression.

Coffee which is one of the most popular beverages is under great attention because its attractive pharmacological effects such as anti-cancer properties, antioxidant and cell protective effects. Coffea arabica metabolites like cafestol and kahweol belonging to class of diterpene are expected to be as biotherapeutic drugs for maintaining human health via preventing serious illnesses. However, the understanding of the effects of these two diterpenes against human leukemia cells is still poor. In this study, we investigated the influences of these two coffee diterpenes on the viability and the all-trans retinoic acid (ATRA)-induced superoxide anion (O₂^-)-generating ability of human leukemia U937 cells. Cafestol and kahweol reduced cell viability at a concentration of 50 μM. In addition, 1 μM ATRA significantly reduced viability with cafestol at 48 hr and kahweol at 24 hr respectively. On the other hand, 20 μM these two coffee diterpenes brought about moderate up-regulation of the ATRA-induced O₂^--generating ability. Quantitative RT-PCR and immunoblotting revealed that these two coffee diterpenes significantly up-regulate the ATRA-induced O₂^--generating ability via enhancing gene expression levels of gp91-phox, which is an essential factor for the O₂^--generating ability of leukocytes. These findings demonstrated that cafestol and kahweol show not only the ATRA-enhanced cytotoxicity but also the promoting effects on the ATRA-induced O₂^--generating ability via up-regulation of gp91-phox gene expression.