Porcine cytochrome 2A19 and 2E1

Key Role of Porcine Cytochrome P450 2A19 in the Bioactivation of Aflatoxin B1 in the Liver

The metabolic transformation of aflatoxin B1 (AFB1) in pigs remains understudied, presenting a gap in our toxicological understanding compared with extensive human-based research. Here, we found that the main products of AFB1 in porcine liver microsomes (PLMs) were AFB1-8,9-epoxide (AFBO), the generation of which correlated strongly with the protein levels and activities of cytochrome P450 (CYP)3A and CYP2A. In addition, we found that porcine CYP2A19 can transform AFB1 into AFBO, and its metabolic activity was stronger than the other CYPs we have reported, including CYP1A2, CYP3A29, and CYP3A46. Furthermore, we stably transfected all identified CYPs in HepLi cells and found that CYP2A19 stable transfected HepLi cells showed more sensitivity in AFB1-induced DNA adducts, DNA damage, and γH2AX formation than the other three stable cell lines. Moreover, the CYP2A19 N297A mutant that lost catalytic activity toward AFB1 totally eliminated AFB1-induced AFB1-DNA adducts and γH2AX formations in CYP2A19 stable transfected HepLi cells. These results indicate that CYP2A19 mainly mediated AFB1-induced cytotoxicity through metabolizing AFB1 into a highly reactive AFBO, promoting DNA adduct formation and DNA damage, and lastly leading to cell death. This study advances the current understanding of AFB1 bioactivation in pigs and provides a promising target to reduce porcine aflatoxicosis.

The therapeutic potential of dietary intervention: based on the mechanism of a tryptophan derivative-indole propionic acid on metabolic disorders

Tryptophan (TRP) contributes to individual immune homeostasis and good condition via three complex metabolism pathways (5-hydroxytryptamine (5-HT), kynurenine (KP), and gut microbiota pathway). Indole propionic acid (IPA), one of the TRP derivatives of the microbiota pathway, has raised more attention because of its impact on metabolic disorders. Here, we retrospect increasing evidence that TRP metabolites/IPA derived from its proteolysis impact host health and disease. IPA can activate the immune system through aryl hydrocarbon receptor (AHR) and/or Pregnane X receptor (PXR) as a vital mediator among diet-caused host and microbe cross-talk. Different levels of IPA in systemic circulation can predict the risk of NAFLD, T2DM, and CVD. IPA is suggested to alleviate cognitive impairment from oxidative damage, reduce gut inflammation, inhibit lipid accumulation and attenuate the symptoms of NAFLD, putatively enhance the intestinal epithelial barrier, and maintain intestinal homeostasis. Now, we provide a general description of the relationships between IPA and various physiological and pathological processes, which support an opportunity for diet intervention for metabolic diseases.

Research update on aflatoxins toxicity, metabolism, distribution, and detection: A concise overview

Serious health risks associated with the consumption of food products contaminated with aflatoxins (AFs) are worldwide recognized and depend predominantly on consumed AF concentration by diet. A low concentration of aflatoxins in cereals and related food commodities is unavoidable, especially in subtropic and tropic regions. Accordingly, risk assessment guidelines established by regulatory bodies in different countries help in the prevention of aflatoxin intoxication and the protection of public health. By assessing the maximal levels of aflatoxins in food products which are a potential risk to human health, it's possible to establish appropriate risk management strategies. Regarding, a few factors are crucial for making a rational risk management decision, such as toxicological profile, adequate information concerning the exposure duration, availability of routine and some novel analytical techniques, socioeconomic factors, food intake patterns, and maximal allowed levels of each aflatoxin in different food products which may be varied between countries.

Quantitative Proteomic Analysis of Tibetan Pig Livers at Different Altitudes

In this study, the differences in protein profiles between the livers of Shannan Tibetan pigs (SNT), Linzhi Tibetan pigs (LZT) and Jiuzhaigou Tibetan pigs (JZT) were comparatively analyzed by tandem mass spectrometry-labeling quantitative proteomics. A total of 6804 proteins were identified: 6471 were quantified and 1095 were screened as differentially expressed proteins (DEPs). Bioinformatics analysis results show that, compared with JZT livers, up-regulated DEPs in SNT and LZT livers mainly promoted hepatic detoxification through steroid hormone biosynthesis and participated in lipid metabolism to maintain body energy homeostasis, immune response and immune regulation, while down-regulated DEPs were mainly involved in lipid metabolism and immune regulation. Three proteases closely related to hepatic fatty acid oxidation were down-regulated in enzymatic activity, indicating higher levels of lipid oxidation in SNT and LZT livers than in JZT livers. Down-regulation of the expression of ten immunoglobulins suggests that JZT are more susceptible to autoimmune diseases. It is highly likely that these differences in lipid metabolism and immune-related proteins are in response to the ecological environment at different altitudes, and the findings contribute to the understanding of the potential molecular link between Tibetan pig livers and the environment.

Aflatoxins in Feed: Types, Metabolism, Health Consequences in Swine and Mitigation Strategies

Feeding farm animals with aflatoxin-contaminated feed can cause various severe toxic effects, leading to increased susceptibility to infectious diseases and increased mortality, weight loss, poor performance and reduced reproductive capability. Following ingestion of contaminated foodstuffs, aflatoxins are metabolized and biotransformed differently in animals. Swine metabolism is not effective in detoxifying and excreting aflatoxins, meaning the risk of aflatoxicosis is increased. Thus, it is of great importance to elucidate the metabolism and all metabolic pathways associated with this mycotoxin. The damage induced by AFB1 in cells and tissues consists of inhibition of cell proliferation, carcinogenicity, immunosuppression, mutagenicity, oxidative stress, lipid peroxidation and DNA damage, leading to pathological lesions in the liver, spleen, lymph node, kidney, uterus, heart, and lungs of swine. At present, it is a challenging task and of serious concern to completely remove aflatoxins and their metabolites from feedstuff; thus, the aim of this study was a literature review on the deleterious effects of aflatoxins on swine metabolism, as well as alternatives that contribute to the detoxification or amelioration of aflatoxin-induced effects in farm animal feed.

Nuclear Receptor Pathways Mediating the Development of Boar Taint

The nuclear receptors PXR, CAR, and FXR are activated by various ligands and function as transcription factors to control the expression of genes that regulate the synthesis and metabolism of androstenone and skatole. These compounds are produced in entire male pigs and accumulate in the fat to cause the development of a meat quality issue known as boar taint. The extent of this accumulation is influenced by the synthesis and hepatic clearance of androstenone and skatole. For this reason, PXR, CAR, and FXR-mediated signaling pathways have garnered interest as potential targets for specialized treatments designed to reduce the development of boar taint. Recent research has also identified several metabolites produced by gut microbes that act as ligands for these nuclear receptors (e.g., tryptophan metabolites, short-chain fatty acids, bile acids); however, the connection between the gut microbiome and boar taint development is not clear. In this review, we describe the nuclear receptor signaling pathways that regulate the synthesis and metabolism of boar taint compounds and outline the genes involved. We also discuss several microbial-derived metabolites and dietary additives that are known or suspected nuclear receptor ligands and suggest how these compounds could be used to develop novel treatments for boar taint.

Regulation of drug-metabolizing enzymes by sex-related hormones: clinical implications for transgender medicine

Transgender medicine is a diverse and growing clinical field with unmet gaps in pharmacological knowledge. Hormone therapy (testosterone or estrogen treatment), one part of the standard of medical care for transgender adults, aligns secondary sex characteristics with an individual's gender identity and expression. Despite established effects of sex steroids on drug-metabolizing enzyme expression and activity in vitro and in animal models, the effect of long-term, supraphysiological sex hormone treatment on drug metabolism in transgender adults is not yet established. Here, we synthesize available in vitro and animal model data with pharmacological concepts in transgender medicine to predict potential effects of sex steroids on drug-metabolizing enzymes, and their relationship with potential hormone-drug interactions, in transgender medicine.

Hepatic Cytochrome P450 Abundance and Activity in the Developing and Adult Göttingen Minipig: Pivotal Data for PBPK Modeling

The Göttingen Minipig is gaining ground as nonrodent species in safety testing of drugs for pediatric indications. Due to developmental changes in pharmacokinetics and pharmacodynamics, physiologically based pharmacokinetic (PBPK) models are built to better predict drug exposure in children and to aid species selection for nonclinical safety studies. These PBPK models require high quality physiological and ADME data such as protein abundance of drug metabolizing enzymes. These data are available for man and rat, but scarce for the Göttingen Minipig. The aim of this study was to assess hepatic cytochrome P450 (CYP) protein abundance in the developing Göttingen Minipig by using mass spectrometry. In addition, sex-related differences in CYP protein abundance and correlation of CYP enzyme activity with CYP protein abundance were assessed. The following age groups were included: gestational day (GD) 84–86 (n = 8), GD 108 (n = 6), postnatal day (PND) 1 (n = 8), PND 3 (n = 8), PND 7 (n = 8), PND 28 (n = 8) and adult (n = 8). Liver microsomes were extracted and protein abundance was compared to that in adult animals. Next, the CYP protein abundance was correlated to CYP enzyme activity in the same biological samples. In general, CYP protein abundance gradually increased during development. However, we observed a stable protein expression over time for CYP4A24 and CYP20A1 and for CYP51A1, a high protein expression during the fetal stages was followed by a decrease during the first month of life and an increase toward adulthood. Sex-related differences were observed for CYP4V2_2a and CYP20A1 at PND 1 with highest expression in females for both isoforms. In the adult samples, sex-related differences were detected for CYP1A1, CYP1A2, CYP2A19, CYP2E1_2, CYP3A22, CYP4V2_2a and CYP4V2_2b with higher values in female compared to male Göttingen Minipigs. The correlation analysis between CYP protein abundance and CYP enzyme activity showed that CYP3A22 protein abundance correlated clearly with the metabolism of midazolam at PND 7. These data are remarkably comparable to human data and provide a valuable step forward in the construction of a neonatal and juvenile Göttingen Minipig PBPK model.

The Effectiveness of Dietary Byproduct Antioxidants on Induced CYP Genes Expression and Histological Alteration in Piglets Liver and Kidney Fed with Aflatoxin B1 and Ochratoxin A

The purpose of this study was to investigate the potential of a byproduct mixture derived from grapeseed and sea buckthorn oil industry to mitigate the harmful damage produced by ochratoxin A and aflatoxin B1 at hepatic and renal level in piglets after weaning. Forty cross-bred TOPIGS-40 hybrid piglets after weaning were assigned to three experimental groups (E1, E2, E3) and one control group (C), and fed with experimental diets for 30 days. The basal diet was served as a control and contained normal compound feed for starter piglets without mycotoxins. The experimental groups were fed as follows: E1-basal diet plus a mixture (1:1) of two byproducts (grapeseed and sea buckthorn meal); E2-the basal diet experimentally contaminated with mycotoxins (479 ppb OTA and 62ppb AFB1); and E3-basal diet containing 5% of the mixture (1:1) of grapeseed and sea buckthorn meal and contaminated with the mix of OTA and AFB1. After 4 weeks, the animals were slaughtered, and tissue samples were taken from liver and kidney in order to perform gene expression and histological analysis. The gene expression analysis showed that when weaned piglets were fed with contaminated diet, the expression of most analyzed genes was downregulated. Among the CYP450 family, CYP1A2 was the gene with the highest downregulation. According to these results, in liver, we found that mycotoxins induced histomorphological alterations in liver and kidney and had an effect on the expression level of CYP1A2, CYP2A19, CYP2E1, and CYP3A29, but we did not detect important changes in the expression level of CY4A24, MRP2 and GSTA1 genes.

The Neonatal and Juvenile Pig in Pediatric Drug Discovery and Development

Pharmacotherapy in pediatric patients is challenging in view of the maturation of organ systems and processes that affect pharmacokinetics and pharmacodynamics. Especially for the youngest age groups and for pediatric-only indications, neonatal and juvenile animal models can be useful to assess drug safety and to better understand the mechanisms of diseases or conditions. In this respect, the use of neonatal and juvenile pigs in the field of pediatric drug discovery and development is promising, although still limited at this point. This review summarizes the comparative postnatal development of pigs and humans and discusses the advantages of the juvenile pig in view of developmental pharmacology, pediatric diseases, drug discovery and drug safety testing. Furthermore, limitations and unexplored aspects of this large animal model are covered. At this point in time, the potential of the neonatal and juvenile pig as nonclinical safety models for pediatric drug development is underexplored.

Sex dictates the constitutive expression of hepatic cytochrome P450 isoforms in Göttingen minipigs

The cytochrome P450 enzyme (CYP) family includes key enzymes for the metabolism of drugs and xenobiotics. Several animal models have been used to determine the metabolite profile of specific drugs. Among these are porcine microsomes prepared from Göttingen minipigs. However, CYP expression profile in microsomes from this pig breed is unknown. In the present study, we determined the mRNA and protein profiles of a comprehensive selection of CYPs in microsomes prepared from male and female Göttingen minipigs. Using RT-PCR, western blotting and mass spectroscopy, we found that the expression levels of CYP1A, CYP2A and CYP2E1 were significantly higher in females than males. Moreover, some of the transcription factors controlling CYP transcription also showed a sex-dependent expression pattern. Conversely, expression of CYP2B, CYP2D and CYP3A was comparable between sexes. The overall CYP expression distribution showed high similarity with what previously been reported in humans. In conclusion, our results suggest that Göttingen minipigs are a reliable model for studying CYPs.

Porcine cytochrome 2A19 and 2E1

Cytochrome P450 (CYP) is a major group of enzymes, which conduct Phase I metabolism. Among commonly used animal models, the pig has been suggested as the most suitable model for investigating drug metabolism in human beings. Moreover, porcine CYP2A19 and CYP2E1 are responsible for the biotransformation of both endogenous and exogenous compounds such as 3‐methylindole (skatole), sex hormones and food compounds. However, little is known about the regulation of porcine CYP2A19 and CYP2E1. In this MiniReview, we summarise the current knowledge about the regulation of porcine CYP2A19 and CYP2E1 by environmental, biological and dietary factors. Finally, we reflect on the need for further research, to clarify the interaction between active feed components and the porcine CYP system.