Parathyroid hormone contributes to the down-regulation of cytochrome P450 3A through the cAMP/PI3K/PKC/PKA/NF-κB signaling pathway in secondary hyperparathyroidism

The Dietary Fiber Inulin Slows Progression of Chronic Kidney Disease-Mineral Bone Disorder (CKD-MBD) in a Rat Model of CKD

Chronic kidney disease (CKD)-mineral bone disorder (CKD-MBD) leads to fractures and cardiovascular disease. Observational studies suggest beneficial effects of dietary fiber on both bone and cardiovascular outcomes, but the effect of fiber on CKD-MBD is unknown. To determine the effect of fiber on CKD-MBD, we fed the Cy/+ rat with progressive CKD a casein-based diet of 0.7% phosphate with 10% inulin (fermentable fiber) or cellulose (non-fermentable fiber) from 22 weeks to either 30 or 32 weeks of age (~30% and ~15% of normal kidney function; CKD 4 and 5). We assessed CKD-MBD end points of biochemistry, bone quantity and quality, cardiovascular health, and cecal microbiota and serum gut-derived uremic toxins. Results were analyzed by two-way analysis of variance (ANOVA) to evaluate the main effects of CKD stage and inulin, and their interaction. The results showed that in CKD animals, inulin did not alter kidney function but reduced the increase from stage 4 to 5 in serum levels of phosphate and parathyroid hormone, but not fibroblast growth factor-23 (FGF23). Bone turnover and cortical bone parameters were similarly improved but mechanical properties were not altered. Inulin slowed progression of aorta and cardiac calcification, left ventricular mass index, and fibrosis. To understand the mechanism, we assessed intestinal microbiota and found changes in alpha and beta diversity and significant changes in several taxa with inulin, together with a reduction in circulating gut derived uremic toxins such as indoxyl sulfate and short-chain fatty acids. In conclusion, the addition of the fermentable fiber inulin to the diet of CKD rats led to a slowed progression of CKD-MBD without affecting kidney function, likely mediated by changes in the gut microbiota composition and lowered gut-derived uremic toxins. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC. on behalf of American Society for Bone and Mineral Research.

Evaluation of effects of indoxyl sulfate and parathyroid hormone on CYP3A activity considering the influence of CYP3A5 gene polymorphisms

AIMS

Indoxyl sulfate and parathyroid hormone (PTH), which accumulate in chronic kidney disease (CKD), have been reported to reduce cytochrome P450(CYP)3A activity. Homozygotes of the CYP3A5*3 allele have reduced CYP3A5 activity compared to carriers of at least one CYP3A5*1 allele. 4β-Hydroxycholesterol (4β-OHC) has been established as an endogenous substrate reflecting CYP3A activity. 4β-OHC is produced through hydroxylation by CYP3A4 and CYP3A5 and by autoxidation of cholesterol, whereas 4α-hydroxycholesterol (4α-OHC) is produced solely by autoxidation of cholesterol. This study focused on CKD patients and evaluated the effects of plasma indoxyl sulfate and intact-PTH concentrations on plasma 4β-OHC concentration, 4β-OHC/total cholesterol ratio and 4β-OHC-4α-OHC, with consideration of the influence of CYP3A5 polymorphism.

METHODS

Sixty-three CKD patients were analysed and divided into CYP3A5 carrier group (n = 26) and non-carrier group (n = 37).

RESULTS

Plasma indoxyl sulfate significantly correlated inversely with 4β-OHC concentration and with 4β-OHC-4α-OHC in both the CYP3A5*1 carrier group (r = -0.42, P = .034; r = -0.39, P = .050, respectively) and the non-carrier group (r = -0.45, P = .0054; r = -0.39, P = .019, respectively). However, multiple regression analysis did not identify plasma indoxyl sulfate concentration as a significant independent factor associated with any of the CYP3A activity indices. There was no significant correlation between plasma intact-PTH concentration and any of the CYP3A activity indices.

CONCLUSIONS

The present results suggest that plasma indoxyl sulfate and intact-PTH concentrations do not have clinically significant effects on CYP3A activity in patients with CKD.

Evaluation of Renal Impairment Influence on Metabolic Drug Clearance using a Modelling Approach

BACKGROUND AND OBJECTIVE

Chronic kidney disease (CKD) may alter drug renal elimination but is also known for interacting with hepatic metabolism via multiple uremic components. However, few global models, considering the five major cytochromes, have been published, and none specifically address the decrease in cytochrome P450 (CYP450) activity. The aim of our study was to estimate the possibility of quantifying residual cytochrome activity as a function of filtration rate, according to the data available in the literature.

METHODS

For each drug in the DDI-predictor database, we collected available pharmacokinetic data comparing drug exposition in the healthy patient and in various stages of CKD, before building a model capable of predicting the variation of exposure according to the degree of renal damage. We followed an In vivo Mechanistic Static Model (IMSM) approach, previously validated for predicting change in liver clearance. We estimated the remaining fraction parameters at glomerular filtration rate (GFR) = 0 and the alpha value of GFR to 50% impairment for the 5 major cytochromes using a non-linear constrained regression using Matlab software.

RESULTS

Thirty-one compounds had usable pharmacokinetic data, with 51 AUC ratios between healthy and renal impaired patients. The remaining CYP3A4 activity was estimated to be 0.4 when CYP2D6, 2C9, 2C19 and 1A2 activity was estimated to be 0.43; 1; 0.73 and 0.7, respectively. The alpha value was estimated to be at 6.62; 25; 9.8; 1.38 and 11.04 for each cytochrome. In comparison with published data, all estimates but one were correctly predicted in the range of 0.5-2.

CONCLUSION

Our approach was able to describe the impact of CKD on metabolic elimination. Modelling this process makes it possible to anticipate changes in clearance and drug exposure in CKD patients, with the advantage of greater simplicity than approaches based on physiologically-based pharmacokinetic modelling. However, a precise estimation of the impact of renal failure is not possible with an IMSM approach due to the large variability of the published data, and thus should rely on specific pharmacokinetic modelling for narrow therapeutic margin drugs.

The Dietary Fermentable Fiber Inulin Alters the Intestinal Microbiome and Improves Chronic Kidney Disease Mineral-Bone Disorder in a Rat Model of CKD

Background

Dietary fiber is important for a healthy diet, but intake is low in CKD patients and the impact this has on the manifestations of CKD-Mineral Bone Disorder (MBD) is unknown.

Methods

The Cy/+ rat with progressive CKD was fed a casein-based diet of 0.7% phosphate with 10% inulin (fermentable fiber) or cellulose (non-fermentable fiber) from 22 weeks to either 30 or 32 weeks of age (~30 and ~15 % of normal kidney function). We assessed CKD-MBD, cecal microbiota, and serum gut-derived uremic toxins. Two-way ANOVA was used to evaluate the effect of age and inulin diet, and their interaction.

Results

In CKD animals, dietary inulin led to changes in microbiota alpha and beta diversity at 30 and 32 weeks, with higher relative abundance of several taxa, including Bifidobacterium and Bacteroides , and lower Lactobacillus . Inulin reduced serum levels of gut-derived uremic toxins, phosphate, and parathyroid hormone, but not fibroblast growth factor-23. Dietary inulin decreased aorta and cardiac calcification and reduced left ventricular mass index and cardiac fibrosis. Bone turnover and cortical bone parameters were improved with inulin; however, bone mechanical properties were not altered.

Conclusions

The addition of the fermentable fiber inulin to the diet of CKD rats led to changes in the gut microbiota composition, lowered gut-derived uremic toxins, and improved most parameters of CKD-MBD. Future studies should assess this fiber as an additive therapy to other pharmacologic and diet interventions in CKD.

Significance Statement

Dietary fiber has well established beneficial health effects. However, the impact of fermentable dietary fiber on the intestinal microbiome and CKD-MBD is poorly understood. We used an animal model of progressive CKD and demonstrated that the addition of 10% of the fermentable fiber inulin to the diet altered the intestinal microbiota and lowered circulating gut-derived uremic toxins, phosphorus, and parathyroid hormone. These changes were associated with improved cortical bone parameters, lower vascular calcification, and reduced cardiac hypertrophy, fibrosis and calcification. Taken together, dietary fermentable fiber may be a novel additive intervention to traditional therapies of CKD-MBD.

New Insight Concerning Therapeutic Drug Monitoring-The Importance of the Concept of Psychonephrology

Recently, the concept of psychonephrology was developed and has been recognized as a field of study that focuses on nephrology and mental health fields, such as psychiatry and psychosomatic medicine. Indeed, patients with chronic kidney disease frequently suffer from mental problems as the disease stage progresses. Most psychotropic drugs are hepatically metabolized, but some are unmetabolized and eliminated renally. However, renal disease may affect the pharmacokinetics of many psychotropic drugs, as the decreased renal function not only delays the urinary excretion of the drug and its metabolites but also alters various pharmacokinetic factors, such as protein-binding, enterohepatic circulation, and activity of drug-metabolizing enzymes. Therefore, when prescribing drug therapy for patients with both renal disease and mental issues, we should consider reducing the dosage of psychotropic drugs that are eliminated mainly via the kidney and also carefully monitor the blood drug concentrations of other drugs with a high extrarenal clearance, such as those that are largely metabolized in the liver. Furthermore, we should carefully consider the dialyzability of each psychotropic drug, as the dialyzability impacts the drug clearance in patients with end-stage renal failure undergoing dialysis. Therapeutic drug monitoring (TDM) may be a useful tool for adjusting the dosage of psychotropic drugs appropriately in patients with renal disease. We herein review the pharmacokinetic considerations for psychotropic drugs in patients with renal disease as well as those undergoing dialysis and offer new insight concerning TDM in the field of psychonephrology.

Population Pharmacokinetic Modelling for Nifedipine to Evaluate the Effect of Parathyroid Hormone on CYP3A in Patients with Chronic Kidney Disease

Purpose

Parathyroid hormone (PTH) can induce the downregulation of CYP3A in chronic kidney disease (CKD). Nevertheless, the effect of PTH on CYP3A-mediated clearance pathways from a clinical perspective remains unclear.

Methods

This study employed population pharmacokinetic (PopPK) modeling to delineate potential changes in CYP3A activity in patients with CKD. Pharmacokinetic data for nifedipine, a typical CYP3A substrate, as well as covariate information, were prospectively collected from 157 patients with a total of 612 concentrations. PopPK data analysis was performed using a nonlinear mixed-effects model.

Results

The pharmacokinetics of nifedipine were optimally described according to a one-compartment model with zero-order absorption and first-order elimination. The estimated population parameters (and interindividual variability) were apparent clearance (CL/F) 49.61 L/h (58.33%) and apparent volume of distribution (V/F) 2300.26 L (45.62%), and the PTH level negatively correlated with CL/F. In comparison with the reference level, it was observed that the dosage of nifedipine should be reduced with the maximum boundary value of PTH, after a Monte Carlo simulation.

Conclusion

This study provides insight into the effects of PTH on CYP3A-mediated clearance pathways. Moreover, PTH could be used as a guide for the appropriate administration of CYP3A eliminated drugs in patients with CKD.

Involvement of the Parathyroid Hormone-Related Protein on Changes in the CYP3A Expression in Cancer Cachexia

Parathyroid hormone-related protein (PTHrP), which is secreted from a tumor, contributes to the progression of cachexia, a condition that is observed in half of all cancer patients. Although drug clearance was reported to decrease in patients with cancer cachexia, the details have not been clarified. The present study reports on an investigation of whether PTHrP is involved in the alternation of drug metabolism in cases of cancer cachexia. Cancer cachexia model rats with elevated serum PTHrP levels showed a significant decrease in hepatic and intestinal CYP3A2 protein expression. When midazolam, a CYP3A substrate drug, was administered intravenously or orally to the cancer cachexia rats, its area under the curve (AUC) was increased by about 2 and 5 times, as compared to the control group. Accordingly, the bioavailability of midazolam was increased by about 3 times, thus enhancing its pharmacological effect. In vitro experiments using HepG2 cells and Caco-2 cells showed that the addition of serum from cancer cachexia rats or active PTHrP (1-34) to each cell resulted in a significant decrease in the expression of CYP3A4 mRNA. Treatment with a cell-permeable cAMP analog also resulted in a decreased CYP3A4 expression. Pretreatment with protein kinase A (PKA), protein kinase C (PKC), and nuclear factor-kappa B (NF-κB) inhibitors recovered the decrease in CYP3A4 expression that was induced by PTHrP (1-34). These results suggest that PTHrP suppresses CYP3A expression via the cAMP/PKA/PKC/NF-κB pathway. Therefore, it is likely that PTHrP would be involved in the changes in drug metabolism observed in cancer cachexia.

Variation in Expression of Cytochrome P450 3A Isoforms and Toxicological Effects: Endo- and Exogenous Substances as Regulatory Factors and Substrates

The CYP3A subfamily, which includes isoforms CYP3A4, CYP3A5, and CYP3A7 in humans, plays important roles in the metabolism of various endogenous and exogenous substances. Gene and protein expression of CYP3A4, CYP3A5, and CYP3A7 show large inter-individual differences, which are caused by many endogenous and exogenous factors. Inter-individual differences can cause negative outcomes, such as adverse drug events and disease development. Therefore, it is important to understand the variations in CYP3A expression caused by endo- and exogenous factors, as well as the variation in the metabolism and kinetics of endo- and exogenous substrates. In this review, we summarize the factors regulating CYP3A expression, such as bile acids, hormones, microRNA, inflammatory cytokines, drugs, environmental chemicals, and dietary factors. In addition, variations in CYP3A expression under pathological conditions, such as coronavirus disease 2019 and liver diseases, are described as examples of the physiological effects of endogenous factors. We also summarize endogenous and exogenous substrates metabolized by CYP3A isoforms, such as cholesterol, bile acids, hormones, arachidonic acid, vitamin D, and drugs. The relationship between the changes in the kinetics of these substrates and the toxicological effects in our bodies are discussed. The usefulness of these substrates and metabolites as endogenous biomarkers for CYP3A activity is also discussed. Notably, we focused on discrimination between CYP3A4, CYP3A5, and CYP3A7 to understand inter-individual differences in CYP3A expression and function.

Parathyroid Hormone Induces Transition of Myofibroblasts in Arteriovenous Fistula and Increases Maturation Failure

CONTEXT

Arteriovenous fistula (AVF) maturation failure remains a clinical dilemma, and its pathobiology is largely unclear. Secondary hyperparathyroidism is a complication of chronic renal failure that is associated with cardiovascular disease. While parathyroid hormone (PTH) has a prosclerotic effect on vascular smooth muscle cells (VSMCs), its role in AVF maturation failure remained unknown.

OBJECTIVE

This work aimed to investigate the association between plasma PTH and AVF maturation.

METHODS

Patients receiving AVF creation were enrolled retrospectively. A mouse model of secondary hyperparathyroidism and aortocaval AVF was used to investigate the effect of PTH on an AVF lesion. A cell model of VSMCs treated with PTH in a pressurized culture system was used to disclose the signaling pathway underlying the effect of PTH on an AVF lesion.

RESULTS

In patients receiving AVF creation, higher PTH was associated with an increased risk for maturation failure. In a mouse model, vascular wall thickness and myofibroblasts of AVF significantly increased with higher PTH. When the same mice were treated with cinacalcet, AVF lesions were attenuated by suppression of PTH. A cell model showed that PTH increased the marker of myofibroblasts, integrin β6 subunit (ITGB6), via the phosphorylated protein kinase B pathway. Finally, in the same model of mice AVF, higher PTH also increased the expression of ITGB6 in the smooth muscle layer of AVF, suggesting the transition to myofibroblast.

CONCLUSION

Overall, our results suggest that higher PTH increased the risk of AVF maturation failure through increasing the transition of VSMCs to myofibroblasts. Lowering PTH may be a strategy to enhance AVF maturation.

Effect of Chronic Kidney Disease on Hepatic Clearance of Drugs in Rats

The pharmacokinetics of some hepatically cleared drugs have been reported to fluctuate in patients with renal impairment, but the definitive factors have not been clarified. We compared the pharmacokinetics of some drugs with different hepatic elimination processes in a chronic kidney disease (CKD) rat model, to optimize their administration during kidney injury. We chose indocyanine green (ICG), midazolam (MDZ), and acetaminophen (APAP) as reference drugs to determine changes in hepatic clearance pathways in presence of CKD. Drugs were intravenously administered via the jugular vein to the CKD model rats, previously established by adenine administration, and then, blood, bile, and urine samples were collected. The plasma concentration of ICG, which is eliminated into the bile without biotransformation, increased; and its total body clearance (CL_tot) significantly decreased in the CKD group compared to the control group. Moreover, the plasma concentrations of MDZ and APAP, metabolized in the liver by CYP3A and Ugt1a6 enzymes, respectively, were higher in the CKD group than in the control group. The biliary clearances of APAP and its derivative APAP-glucuronide increased in the CKD group, whereas their renal clearances were markedly decreased with respect to those in the control group. Altogether, plasma concentrations of some hepatically eliminated drugs increased in the CKD rat model, but depending on their pharmacokinetic characteristics. This study provides useful information for optimizing the administration of some hepatically cleared drugs in CKD patients.

Association of CYP3A5 polymorphisms and parathyroid hormone with blood level of tacrolimus in patients with end-stage renal disease

Because tacrolimus is predominantly metabolized by CYP3A, the blood concentration/dose (C/D) ratio is affected by CYP3A5 polymorphism. Parathyroid hormone (PTH) expression increases in secondary hyperparathyroidism, which is frequently associated with end‐stage renal disease. Recently, PTH has been shown to downregulate CYP3A expression at mRNA level. In this study, we examined the influence of CYP3A5 polymorphism on and association of serum intact‐PTH (iPTH) level with blood tacrolimus concentration in patients with end‐stage renal disease just before kidney transplantation. Forty‐eight patients who satisfied the selection criteria were analyzed. Subjects were classified into two phenotype subgroups: CYP3A5 expressor (CYP3A5*1/*1 and *1/*3; n = 15) and CYP3A5 nonexpressor (CYP3A5*3/*3; n = 33). The blood tacrolimus C/D (per body weight) ratio was significantly lower in CYP3A5 expressors than that in CYP3A5 nonexpressors. A significant positive correlation was found between tacrolimus C/D and iPTH concentrations (r = 0.305, p = 0.035), and the correlation coefficient was higher after excluding 20 patients co‐administered CYP3A inhibitor or inducer (r = 0.428, p = 0.023). A multiple logistic regression analysis by stepwise selection identified CYP3A5 polymorphism and serum iPTH level as significant factors associated with tacrolimus C/D. These results may suggest the importance of dose design considering not only the CYP3A5 phenotype but also serum iPTH level when using tacrolimus in patients who undergo renal transplantation.

Application of Individualized PBPK Modeling of Rate Data to Evaluate the Effect of Hemodialysis on Nonrenal Clearance Pathways

The aim of this study was to apply individualized, physiologically based pharmacokinetic modeling of ¹⁴ CO₂ production rates (iPBPK-R) measured by the erythromycin breath test to characterize the effect of hemodialysis on the function of nonrenal clearance pathways in patients with end-stage renal disease. Twelve patients previously received ¹⁴ C-erythromycin intravenously pre- and post-hemodialysis. Serial breath samples were collected after each dose over 2 hours. Eight PBPK parameters were co-estimated across periods, whereas activity of cytochrome P450 (CYP) 3A4 clearance was independently estimated for each period. Inhibition coefficients for organic anion transporting polypeptide (OATP), P-glycoprotein, and multidrug resistance-associated protein 2 activities were also estimated. Nonrenal clearance parameter estimates were explored regarding sex differences and correlations with uremic toxins and were used in hierarchical cluster analysis (HCA). Relationships between the function of nonrenal clearance pathways and uremic toxin concentrations were explored. Mean CYP 3A4 clearance increased by 2.2% post-hemodialysis. Uptake transporter activity was highly intervariable across hemodialysis. Females had 22% and 30% higher median CYP3A4 activity than males pre- and post-hemodialysis, respectively. Exploratory HCA indicated that using both CYP3A4 and OATP activity parameters at pre- and post-hemodialysis best identifies heterogeneous patients. This is the first study to use the iPBPK-R approach to simultaneously estimate multiple in vivo nonrenal elimination pathways in individual patients with kidney disease and to assess the effect of hemodialysis.

Prediction of the mechanisms of action of Shenkang in chronic kidney disease: A network pharmacology study and experimental validation

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Chinese medicine provides a unique curative treatment of complex chronic diseases, including chronic kidney disease (CKD), which is not effectively treated with the current therapies. The pharmacological mechanisms of Shenkang (SK), a herbal medicine containing rhubarb (Rheum palmatum L. or R. tanguticum Maxim. ex Balf.), red sage (Salvia miltiorrhiza Bunge), safflower (Carthamus tinctorius L.), and astragalus (Astragalus mongholicus Bunge), widely used to treat CKD in China, are still unclear.

AIM OF THE STUDY

In this study, the comprehensive approach used for elucidating the pharmacological mechanisms of SK included the identification of the effective constituents, target prediction and network analysis, by investigating the interacting pathways between these molecules in the context of CKD. These results were validated by performing an in vivo study and by comparison with literature reviews.

MATERIALS AND METHODS

This approach involved the following main steps: first, we constructed a molecular database for SK and screened for active molecules by conducting drug-likeness and drug half-life evaluations; second, we used a weighted ensemble similarity drug-targeting model to accurately identify the direct drug targets of the bioactive constituents; third, we constructed compound-target, target-pathway, and target-disease networks using the Cytoscape 3.2 software and determined the distribution of the targets in tissues and organs according to the BioGPS database. Finally, the resulting drug-target mechanisms were compared with those proposed by previous research on SK and validated in a mouse model of CKD.

RESULTS

By using Network analysis, 88 potential bioactive compounds in the four component herbs of SK and 85 CKD-related targets were identified, including pathways that involve the nuclear factor-κB, mitogen-activated protein kinase, transient receptor potential, and vascular endothelial growth factor, which were categorized as inflammation, proliferation, migration, and permeability modules. The results also included different tissues (kidneys, liver, lungs, and heart) and different disease types (urogenital, metabolic, endocrine, cardiovascular, and immune diseases as well as pathological processes) closely related to CKD. These findings agreed with those reported in the literature. However, our findings with the network pharmacology prediction did not account for all the effects reported for SK found in the literature, such as regulation of the hemodynamics, inhibition of oxidative stress and apoptosis, and the involvement of the transforming growth factor-β/SMAD3, sirtuin/forkhead box protein O (SIRT/FOXO) and B-cell lymphoma-2-associated X protein pathways. The in vivo validation experiment revealed that SK ameliorated CKD through antifibrosis and anti-inflammatory effects, by downregulating the levels of vascular cell adhesion protein 1, vitamin D receptor, cyclooxygenase-2, and matrix metalloproteinase 9 proteins in the unilateral ureteral obstruction mouse model. This was consistent with the predicted target and pathway networks.

CONCLUSIONS

SK exerted a curative effect on CKD and CKD-related diseases by targeting different organs, regulating inflammation and proliferation processes, and inhibiting abnormal extracellular matrix accumulation. Thus, pharmacological network analysis with in vivo validation explained the potential effects and mechanisms of SK in the treatment of CKD. However, these findings need to be further confirmed with clinical studies.

Tissue distribution and characterization of feline cytochrome P450 genes related to polychlorinated biphenyl exposure

Cats have been known to be extremely sensitive to chemical exposures. To understand these model species' sensitivity to chemicals and their toxicities, the expression profiles of xenobiotic-metabolizing enzymes should be studied. Unfortunately, the characterization of cytochrome P450 (CYP), the dominant enzyme in phase I metabolism, in cats has not extensively been studied. Polychlorinated biphenyls (PCBs) are known as CYP inducers in animals, but the information regarding the PCB-induced CYP expression in cats is limited. Therefore, in the present study, we aimed to elucidate the mRNA expression of the CYP1-CYP3 families in the cat tissues and to investigate the CYP mRNA expression related to PCB exposure. In cats, the greatest abundance of CYP1-CYP3 (CYP1A2, CYP2A13, CYP2C41, CYP2D6, CYP2E1, CYP2E2, CYP2F2, CYP2F5, CYP2J2, CYP2U1, and CYP3A132) was expressed in the liver, but some extrahepatic isozymes were found in the kidney (CYP1A1), heart (CYP1B1), lung (CYP2B11 and CYP2S1) and small intestine (CYP3A131). In cats, CYP1A1, CYP1A2 and CYP1B1 were significantly upregulated in the liver as well as in several tissues exposed to PCBs, indicating that these CYPs were distinctly induced by PCBs. The strong correlations between 3,3',4,4'-tetrachlorobiphenyl (CB77) and CYP1A1 and CYP1B1 mRNA expressions were noted, demonstrating that CB77 could be a potent CYP1 inducer. In addition, these CYP isoforms could play an essential role in the PCBs biotransformation, particularly 3-4 Cl-PCBs, because a high hydroxylated metabolite level of 3-4 Cl-OH-PCBs was observed in the liver.

Down-regulation of Cx43 expression on PIH-HUVEC cells attenuates monocyte-endothelial adhesion

INTRODUCTION

Pregnancy-induced hypertension (PIH) is the most common serious complication of pregnancy, resulting in significant maternal and fetal morbidity and mortality. Vasospasm is the main pathogenesis of PIH, which leads to the hemodynamic changes and the injury of vascular endothelial cells. However, the underlying mechanism is still unclear. Monocyte-endothelial adhesion is always considered to be one of the most important indicators of vascular endothelial cell injury. Connexin43 (Cx43) plays an important part in monocyte-endothelial adhesion. Thus, we explored effects of Cx43 on cell adhesion in PIH-induced vascular endothelial cells injury.

METHODS

We obtained human umbilical vein endothelial cells (HUVECs) from patients with or without PIH. Different methods, such as inhibitors: oleamide and Gap26, or specific siRNA were used to alter Cx43 channels function or protein expression in normal or PIH-HUVECs. U937-HUVECs adhesion, adhesion molecules expression, such as VCAM-1 and ICAM-1, and the activity of PI3K/AKT/NF-κB signaling pathway were determined.

RESULTS

Monocyte-endothelial adhesion on PIH-HUVECs was much more obvious than that on normal HUVECs. Inhibition of Cx43 protein expression could attenuate cell adhesion significantly, however, function of Cx43 channels had no effects on it. Alternation of Cx43 protein expression on PIH-HUVECs mediated VCAM-1 and ICAM-1 expression via regulating the activity of PI3K/AKT/NF-κB signaling pathway.

CONCLUSIONS

We firstly reported Cx43 protein expression on PIH-HUVECs was much higher than that on normal HUVECs. Elevation of Cx43 protein expression within the vasculature resulted in PI3K/AKT/NF-κB signaling pathway activation and VCAM-1 and ICAM-1 over-expression, which ultimately lead to monocyte-endothelial adhesion increase.

Role of Parathyroid Hormone in Regulating Transporter and Metabolizing Enzyme Function

Recent studies demonstrate that parathyroid hormone (PTH) not only maintains mineral homeostasis through targeting the kidneys and bone, but also exerts its effects on other organs. For instance, PTH induces urate accumulation through inhibiting the expression of the ABCG2 in both the intestine and the kidney. In addition, PTH downregulates the expression of cytochrome P450 (CYP) 3A, a major enzyme for drug metabolism in both the intestine and liver, resulting in the increase of substrate drug exposure. These functions of PTH are mediated through the PTH receptor (PTHR) signaling. Since PTHR exists in various organs, PTH may regulate other, still unspecified transporters or enzymes in the organs that express PTHR.