Pharmacological Interactions of Jadomycin B with Topoisomerase Poisons in MDA-MB-231 Human Breast Cancer Cells.

Jadomycin B, a natural product isolated from Streptomyces venezuelae, exerts an anti-cancer effect on human triple negative breast cancer cells in vitro and has anti-tumoral effects in vivo in animal models of breast cancer. One proposed mechanism for this anti-cancer effect is through interaction with topoisomerase 2 (TOP2). Based on the previously described interactions between jadomycin B and TOP2 we hypothesized that jadomycin B will act additively with TOP2 poisons and produce a similar functional outcome in eliciting cell cycle arrest. Combined treatments of jadomycin B and the TOP2 poisons doxorubicin or mitoxantrone produced moderately synergistic to additive cytotoxicity (combination index values ranging from 0.72-0.94) in MDA-MB-231 cells. In comparison, combined mitoxantrone and doxorubicin produced additive cytotoxicity (combination index values 0.96-1.11). Jadomycin B combined with the proteosome inhibitor MG132 had additive cytotoxicity (combination index values 0.76-1.18). In contrast, mitoxantrone or doxorubicin cytotoxicity was antagonized by MG132 (combination index values 1.21-2.31). Jadomycin B treatment arrested cells in S-phase (P = 0.0024) as opposed to mitoxantrone which caused G2/M-phase arrest (P < 0.0001). In conclusion, jadomycin B interacts differently than known TOP2 poisons in combination, supporting a novel pharmacological mechanism(s) of action for jadomycin B cytotoxicity.

COVID-19 Vaccines and the Virus: Impact on Drug Metabolism and Pharmacokinetics.

This article reports on an American Society of Pharmacology and Therapeutics, Division of Drug Metabolism and Disposition symposium held at Experimental Biology on April 2, 2022, in Philadelphia. As of July 2022, over 500 million people have been infected with SARS-CoV-2 (the virus causing COVID-19) and over 12 billion vaccine doses have been administered. Clinically significant interactions between viral infections and hepatic drug metabolism were first recognized over 40 years ago during a cluster of pediatric theophylline toxicity cases attributed to reduced hepatic drug metabolism amid an influenza B outbreak. Today, a substantive body of research supports that the activated innate immune response generally decreases hepatic cytochrome P450 activity. The interactions extend to drug transporters and other organs and have the potential to impact drug absorption, distribution, metabolism, and excretion (ADME). Based on this knowledge, altered ADME is predicted with SARS-CoV-2 infection or vaccination. The report begins with a clinical case exploring the possibility of SARS-CoV-2 vaccination increasing clozapine levels. This is followed by discussions of how SARS-CoV-2 infection or vaccines alter the metabolism and disposition of complex drugs, such as nanoparticles and biologics and small molecule therapies. The review concludes with a discussion of the effects of viral infections on placental amino acid transport and their potential to impact fetal development. The session improved our understanding of the impact of emerging viral infections and vaccine technologies on drug metabolism and disposition, which will help mitigate drug toxicity and improve drug and vaccine safety and effectiveness. SIGNIFICANCE STATEMENT: Altered pharmacokinetics of small molecule and complex molecule drugs and fetal brain distribution of amino acids following SARS-CoV-2 infection or immunization are possible. The proposed mechanisms involve decreased liver cytochrome P450 metabolism of small molecules, enhanced innate immune system metabolism of complex molecules, and altered placental and fetal blood-brain barrier amino acid transport, respectively. Future research is needed to understand the effects of these interactions on adverse drug responses, drug and vaccine safety, and effectiveness and fetal neurodevelopment.

Pilot study of jadomycin B pharmacokinetics and anti-tumoral effects in zebrafish larvae and mouse breast cancer xenograft models.

Despite numerous therapeutic options, multidrug resistance (MDR) remains an obstacle to successful breast cancer therapy. Jadomycin B, a natural product derived from Streptomyces venezuelae ISP5230, maintains cytotoxicity in MDR human breast cancer cells. Our objectives were to evaluate the pharmacokinetics, toxicity, anti-tumoral, and anti-metastatic effects of jadomycin B in zebrafish larvae and mice. In a zebrafish larval xenograft model, jadomycin B significantly reduced the proliferation of human MDA-MB-231 cells at or below its maximum tolerated dose (40 µm). In female Balb/C mice, a single intraperitoneal dose (6 mg/kg) was rapidly absorbed with a maximum serum concentration of 3.4 ± 0.27 µm. Jadomycin B concentrations declined biphasically with an elimination half-life of 1.7 ± 0.058 h. In the 4T1 mouse mammary carcinoma model, jadomycin B (12 mg/kg every 12 h from day 6 to 15 after tumor cell injection) decreased primary tumor volume compared to vehicle control. Jadomycin B-treated mice did not exhibit weight loss, nor significant increases in biomarkers of impaired hepatic (alanine aminotransferase) and renal (creatinine) function. In conclusion, jadomycin B demonstrated a good safety profile and provided partial anti-tumoral effects, warranting further dose-escalation safety and efficacy studies in MDR breast cancer models.

Jadomycins: A potential chemotherapy for multi-drug resistant metastatic breast cancer.

Breast cancer causes the most cancer fatalities in women worldwide. Approximately one-third of breast cancers metastasize, or spread from primary tumors to other tissues, and have a 70% 5-year mortality rate. Current breast cancer treatments like doxorubicin and paclitaxel become ineffective when breast cancer cells develop multi-drug resistance and overexpress ATP-binding cassette transporters, as the transporters cause a substantial efflux of the chemotherapies. Jadomycins, a group of molecules isolated from Streptomyces venezuelae ISP5230, are shown to be cytotoxic against a variety of cancers, especially breast cancer. Furthermore, jadomycins retain their cytotoxic properties in multi-drug resistant breast cancer cells, as they are not expelled through ATP-binding cassette transporters. Here, we describe the research that supports the potential use of jadomycins as a novel chemotherapy in the treatment of multi-drug resistant, metastatic breast cancer. We present the supportive findings, as well as the mechanisms of action investigated thus far. These include copper-mediated reactive oxygen species generation, aurora B kinase inhibition, and topoisomerase IIα and IIß inhibition. We also suggest future directions of jadomycin research, which will help to determine if jadomycins can be used as a breast cancer chemotherapy in clinical practice.

S100B as a biomarker of blood-brain barrier disruption after thoracoabdominal aortic aneurysm repair: a secondary analysis from a prospective cohort study.

PURPOSE: The objective of this study was to determine whether the magnitude of the peripheral inflammatory response to cardiovascular surgery is associated with increases in blood-brain barrier (BBB) permeability as reflected by changes in cerebrospinal fluid (CSF)/plasma S100B concentrations. METHODS: We conducted a secondary analysis from a prospective cohort study of 35 patients undergoing elective thoracoabdominal aortic aneurysm repair with (n = 17) or without (n = 18) cardiopulmonary bypass (CPB). Plasma and CSF S100B, interleukin-6 (IL-6), and albumin concentrations were measured at baseline (C0) and serially for up to five days. RESULTS: Following CPB, the median [interquartile range] plasma S100B concentration increased from 58 [32-88] pg·mL-1 at C0 to a maximum concentration (Cmax) of 1,131 [655-1,875] pg·mL-1 over a median time (tmax) of 6.3 [5.9-7.0] hr. In the non-CPB group, the median plasma S100B increased to a lesser extent. There was a delayed increase in CSF S100B to a median Cmax of 436 [406-922] pg·mL-1 in the CPB group at a tmax of 23.7 [18.5-40.2] hr. In the non-CPB group, the CSF concentrations were similar at all time points. In the CPB group, we did not detect significant correlations between plasma and CSF S100B with plasma IL-6 [r = 0.52 (95% confidence interval [CI], -0.061 to 0.84)] and CSF IL-6 [r = 0.53 (95% CI, -0.073 to 0.85)] concentrations, respectively. Correlations of plasma or CSF S100B levels with BBB permeability were not significant. CONCLUSION: The lack of parallel increases in plasma and CSF S100B following CPB indicates that S100B may not be a reliable biomarker for BBB disruption after thoracoabdominal aortic aneurysm repair employing CPB. TRIAL REGISTRATION: www.clinicaltrials.gov (NCT00878371); registered 7 April 2009.

RéSUMé: OBJECTIF: L'objectif de cette étude était de déterminer si l'intensité de la réponse inflammatoire périphérique à la chirurgie cardiovasculaire était associée à une augmentation de la perméabilité de la barrière hémato-encéphalique (BHE), telle que reflétée par des changements dans les concentrations de S100B dans le liquide céphalorachidien (LCR) et le plasma. MéTHODE: Nous avons mené une analyse secondaire à partir d'une étude de cohorte prospective portant sur 35 patients bénéficiant d'une réparation élective d'un anévrisme aortique thoraco-abdominal avec (n = 17) ou sans (n = 18) circulation extracorporelle (CEC). Les concentrations plasmatiques et dans le LCR de S100B, d'interleukine-6 (IL-6) et d'albumine ont été mesurées au départ (C0) et en série jusqu'à cinq jours. RéSULTATS: Après la CEC, la concentration médiane [écart interquartile] plasmatique de S100B est passée de 58 [32­88] pg·mL-1 au départ (C0) à une concentration maximale (Cmax) de 1131 [655­1875] pg·mL-1 sur une période médiane (tmax) de 6,3 [5,9­7,0] h. Dans le groupe sans CEC, la concentration plasmatique médiane de S100B a augmenté dans une moindre mesure. Il y a eu une augmentation retardée de S100B dans le LCR à une Cmax médiane de 436 [406­922] pg·mL-1 dans le groupe CEC à une tmax de 23,7 [18,5­40,2] h. Dans le groupe sans CEC, les concentrations dans le LCR étaient similaires à tous les moments. Dans le groupe CEC, nous n'avons pas détecté de corrélations significatives entre la concentration de S100B dans le plasma et le LCR avec les concentrations plasmatiques d'IL-6 [r = 0,52 (intervalle de confiance [IC] à 95 %, -0,061 à 0,84)] et d'IL-6 dans le LCR [r = 0,53 (IC 95 %, -0,073 à 0,85)], respectivement. Les corrélations entre les taux plasmatiques ou dans le LCR de S100B et la perméabilité de la BHE n'étaient pas significatives. CONCLUSION: L'absence d'augmentations parallèles de la concentration de S100B dans le plasma et le LCR après la CEC indique que la S100B pourrait ne pas être un biomarqueur fiable de la perturbation de la BHE après une réparation d'anévrisme aortique thoraco-abdominal sous CEC. ENREGISTREMENT DE L'éTUDE: www.clinicaltrials.gov (NCT00878371); enregistrée le 7 avril 2009.

COVID-19 pathophysiology and pharmacology: what do we know and how did Canadians respond? A review of Health Canada authorized clinical vaccine and drug trials.

Coronavirus disease 2019 (COVID-19) has resulted in the death of over 18 000 Canadians and has impacted the lives of all Canadians. Many Canadian research groups have expanded their research programs to include COVID-19. Over the past year, our knowledge of this novel disease has grown and has led to the initiation of a number of clinical vaccine and drug trials for the prevention and treatment of COVID-19. Here, we review SARS-CoV-2 (the coronavirus that causes COVID-19) and the natural history of COVID-19, including a timeline of disease progression after SARS-CoV-2 exposure. We also review the pathophysiological effects of COVID-19 on the organ systems that have been implicated in the disease, including the lungs, upper respiratory tract, immune system, central nervous system, cardiovascular system, gastrointestinal organs, the liver, and the kidneys. Then we review general therapeutics strategies that are being applied and investigated for the prevention or treatment of COVID-19, including vaccines, antivirals, immune system enhancers, pulmonary supportive agents, immunosuppressants and (or) anti-inflammatories, and cardiovascular system regulators. Finally, we provide an overview of all current Health Canada authorized clinical drug and vaccine trials for the prevention or treatment of COVID-19.

Metabolism and pharmacokinetics of a novel polyphenol fatty acid ester phloridzin docosahexaenoate in Balb/c female mice.

Flavonoids are known to undergo phase II metabolism and produce metabolites with similar or stronger biological effects compared to the parent flavonoids. However, the limited cellular uptake and bioavailability restrict their clinical use. We synthesized phloridzin docosahexaenoate (PZ-DHA), a novel fatty acid ester of polyphenol, through an acylation reaction with the aim of increasing the cellular availability and stability of the parent biomolecules, phloridzin (PZ) and docosahexaenoic acid (DHA). Here, we report metabolites and pharmacokinetic parameters of PZ-DHA, determined using ultra-high-performance liquid chromatography-electrospray ionization tandem mass spectrometry. PZ-DHA was taken-up by human (MDA-MB-231, MDA-MB-468, and MCF-7) and mouse (4T1) mammary carcinoma and human non-malignant mammary epithelial cells (MCF-10A) in cellular uptake assays. Our results suggested that the acylation improves the cellular uptake of PZ and stability of DHA within cells. In mouse hepatic microsomal assays, two major glucuronides of PZ-DHA, PZ-DHA-4-O-glucuronide and PZ-DHA-4'-O-glucuronide (MW = 923.02 g/mol), were detected. One tri-methylated- (4,4',6'-O-trimethyl-PZ-DHA) (MW = 788.88 g/mol) and one di-sulphated- (PZ-DHA-4,4'-O-disulphide) PZ-DHA metabolite (MW = 906.20 g/mol) were also identified. Intraperitoneal injections of PZ-DHA (100 mg/kg) into Balb/c female mice was rapidly absorbed with a serum Cmax and Tmax of 23.7 µM and 60 min, respectively, and rapidly eliminated (t1/2 = 28.7 min). PZ-DHA and its metabolites are readily distributed throughout the body (Vd = 57 mL) into many organs. We identified in vitro and in vivo metabolites of PZ-DHA, which could be tested for potential use to treat diseases such as cancer in multiple organ systems.

Decitabine Response in Breast Cancer Requires Efficient Drug Processing and Is Not Limited by Multidrug Resistance.

Dysregulation of DNA methylation is an established feature of breast cancers. DNA demethylating therapies like decitabine are proposed for the treatment of triple-negative breast cancers (TNBC) and indicators of response need to be identified. For this purpose, we characterized the effects of decitabine in a panel of 10 breast cancer cell lines and observed a range of sensitivity to decitabine that was not subtype specific. Knockdown of potential key effectors demonstrated the requirement of deoxycytidine kinase (DCK) for decitabine response in breast cancer cells. In treatment-naïve breast tumors, DCK was higher in TNBCs, and DCK levels were sustained or increased post chemotherapy treatment. This suggests that limited DCK levels will not be a barrier to response in patients with TNBC treated with decitabine as a second-line treatment or in a clinical trial. Methylome analysis revealed that genome-wide, region-specific, tumor suppressor gene-specific methylation, and decitabine-induced demethylation did not predict response to decitabine. Gene set enrichment analysis of transcriptome data demonstrated that decitabine induced genes within apoptosis, cell cycle, stress, and immune pathways. Induced genes included those characterized by the viral mimicry response; however, knockdown of key effectors of the pathway did not affect decitabine sensitivity suggesting that breast cancer growth suppression by decitabine is independent of viral mimicry. Finally, taxol-resistant breast cancer cells expressing high levels of multidrug resistance transporter ABCB1 remained sensitive to decitabine, suggesting that the drug could be used as second-line treatment for chemoresistant patients.

Antitumor Activity of Abnormal Cannabidiol and Its Analog O-1602 in Taxol-Resistant Preclinical Models of Breast Cancer.

Cannabinoids exhibit anti-inflammatory and antitumorigenic properties. Contrary to most cannabinoids present in the Cannabis plant, some, such as O-1602 and abnormal cannabidiol, have no or only little affinity to the CB1 or CB2 cannabinoid receptors and instead exert their effects through other receptors. Here, we investigated whether the synthetic regioisomers of cannabidiol, abnormal cannabidiol, and a closely related compound, O-1602, display antitumorigenic effects in cellular models of breast cancer and whether it could reduce tumorigenesis in vivo. Several studies have shown the effects of cannabinoids on chemotherapy-sensitive breast cancer cell lines, but less is known about the antitumorigenic effects of cannabinoids in chemotherapy-resistant cell lines. Paclitaxel-resistant MDA-MB-231 and MCF-7 breast cancer cell lines were used to study the effect of O-1602 and abnormal cannabidiol on viability, apoptosis, and migration. The effects of O-1602 and abnormal cannabidiol on cell viability were completely blocked by the combination of GPR55 and GPR18-specific siRNAs. Both O-1602 and abnormal cannabidiol decreased viability in paclitaxel-resistant breast cancer cells in a concentration-dependent manner through induction of apoptosis. The effect of these cannabinoids on tumor growth in vivo was studied in a zebrafish xenograft model. In this model, treatment with O-1602 and abnormal cannabidiol (2 µM) significantly reduced tumor growth. Our results suggest that atypical cannabinoids, like O-1602 and abnormal cannabidiol, exert antitumorigenic effects on paclitaxel-resistant breast cancer cells. Due to their lack of central sedation and psychoactive effects, these atypical cannabinoids could represent new leads for the development of additional anticancer treatments when resistance to conventional chemotherapy occurs during the treatment of breast and possibly other cancers.

More Than an Adipokine: The Complex Roles of Chemerin Signaling in Cancer.

Chemerin is widely recognized as an adipokine, with diverse biological roles in cellular differentiation and metabolism, as well as a leukocyte chemoattractant. Research investigating the role of chemerin in the obesity-cancer relationship has provided evidence both for pro- and anti-cancer effects. The tumor-promoting effects of chemerin primarily involve direct effects on migration, invasion, and metastasis as well as growth and proliferation of cancer cells. Chemerin can also promote tumor growth via the recruitment of tumor-supporting mesenchymal stromal cells and stimulation of angiogenesis pathways in endothelial cells. In contrast, the majority of evidence supports that the tumor-suppressing effects of chemerin are immune-mediated and result in a shift from immunosuppressive to immunogenic cell populations within the tumor microenvironment. Systemic chemerin and chemerin produced within the tumor microenvironment may contribute to these effects via signaling through CMKLR1 (chemerin1), GPR1 (chemerin2), and CCLR2 on target cells. As such, inhibition or activation of chemerin signaling could be beneficial as a therapeutic approach depending on the type of cancer. Additional studies are required to determine if obesity influences cancer initiation or progression through increased adipose tissue production of chemerin and/or altered chemerin processing that leads to changes in chemerin signaling in the tumor microenvironment.

Isolation of a jadomycin incorporating L-ornithine, analysis of antimicrobial activity and jadomycin reactive oxygen species (ROS) generation in MDA-MB-231 breast cancer cells.

Herein, we report the characterization and antimicrobial activity of a previously unreported jadomycin (1) obtained from a culture of S. venezuelae ISP5230 with L-ornithine (Orn). 1 arises from the rearrangement of a putative five-membered ring containing jadomycin incorporating Orn, whereby intramolecular attack of the E-ring carbonyl from the δ-NH2 group of the Orn side chain results in collapse of the oxazolone ring and formation of a stable six-membered lactam. This rearrangement produces a jadomycin with a 3a hemiaminal position that is susceptible to solvolysis. A structure-activity relationship is discussed based on the antimicrobial activity of 1 compared to previously reported jadomycins, providing evidence that the presence of a 3a hemiaminal enhances activity against Gram-positive bacteria. Additionally, assays to quantify reactive oxygen species (ROS) generation and cell viability were performed using a series of nine jadomycins. Compound 1 was found to produce the highest ROS activity and to possess the greatest cytotoxicity against MDA-MB-231 breast cancer cells.

Post Polyketide Synthase Carbon-Carbon Bond Formation in Type-II PKS-Derived Natural Products from Streptomyces venezuelae.

Polyketide synthase (PKS) derived natural products are biosynthesized by head-to-tail addition of acetate and malonate extender units resulting in linear extended-polyketide chains. Despite the well-documented structural diversity associated with PKS-derived natural products, C-C chain branching deviating from the usual linear pattern is relatively rare. Herein, type-II PKS angucyclic natural products containing a hemiaminal functionality were identified and proposed as the parent of a series of C-C-branched analogues. These C-C linked acetate or pyruvate branching units were located at the α-positions on the extended polyketide chains of jadomycins incorporating 3- and 4-aminomethylbenzoic acids. Labeling studies utilizing [1-13C]-d-glucose provided mechanistic evidence that the C-C bond formation occurred as a result of a previously unidentified post-PKS processing, additional to the enzymes encoded within the biosynthetic gene cluster. Selected compounds were evaluated in cytotoxic or antimicrobial assays.

Jadomycins Inhibit Type II Topoisomerases and Promote DNA Damage and Apoptosis in Multidrug-Resistant Triple-Negative Breast Cancer Cells.

Jadomycins are natural products that kill drug-sensitive and multidrug-resistant (MDR) breast cancer cells. To date, the cytotoxic activity of jadomycins has never been tested in MDR breast cancer cells that are also triple negative. Additionally, there is only a rudimentary understanding of how jadomycins cause cancer cell death, which includes the induction of intracellular reactive oxygen species (ROS). We first created a paclitaxel-resistant, triple-negative breast cancer cell line [paclitaxel-resistant MDA-MB-231 breast cancer cells (231-TXL)] from drug-sensitive control MDA-MB-231 cells (231-CON). Using thiazolyl blue methyltetrazolium bromide cell viability-measuring assays, jadomycins B, S, and F were found to be equipotent in drug-sensitive 231-CON and MDR 231-TXL cells; and using ROS-detecting assays, these jadomycins were determined to increase ROS activity in both cell lines by up to 7.3-fold. Jadomycins caused DNA double-strand breaks in 231-CON and 231-TXL cells as measured by γH2AX Western blotting. Coincubation with the antioxidant N-acetyl cysteine or pro-oxidant auranofin did not affect jadomycin-mediated DNA damage. Jadomycins induced apoptosis in 231-CON and 231-TXL cells as measured by annexin V affinity assays, a process that was retained when ROS were inhibited. This indicated that jadomycins are capable of inducing MDA-MB-231 apoptotic cell death independently of ROS activity. Using quantitative polymerase chain reaction, Western blotting, and direct topoisomerase inhibition assays, it was determined that jadomycins inhibit type II topoisomerases and that jadomycins B and F selectively poison topoisomerase IIß We therefore propose novel mechanisms through which jadomycins induce breast cancer cell death independently of ROS activity, through inhibition or poisoning of type II topoisomerases and the induction of DNA damage and apoptosis.

An observational study examining the effects of a surgically induced inflammatory response on the distribution of morphine and its metabolites into cerebrospinal fluid.

PURPOSE: Morphine is administered intravenously for pain management in the perioperative period. The effect of the inflammatory response to surgery on morphine distribution across the blood-brain barrier (BBB) in humans was investigated. We hypothesized that a graded surgically induced, systemic inflammatory response alters cerebrospinal fluid (CSF) levels of morphine, morphine-3-glucuronide (M3G), and morphine-6-glucuronide (M6G) through a temporary reduction in BBB drug efflux transporter function. METHODS: We conducted a prospective pharmacokinetic study of the plasma and CSF distribution of the P-glycoprotein (PGP) substrate morphine in 33 patients undergoing open thoracic (n = 18) or endovascular (n = 15) aortic aneurysm repair. Morphine was administered with induction of anesthesia and in the intensive care unit. Plasma and CSF concentrations of interleukin (IL)-6, morphine, M3G, M6G, and albumin were measured prior to surgery (baseline), during surgery, and postoperatively every six hours until removal of the CSF drain. The area under the curve (AUC) was determined for plasma and CSF IL-6, morphine, M3G, and M6G concentrations vs time. The primary endpoint measures were the correlations between the morphine, M6G, and M3G AUC CSF/plasma ratios and systemic inflammation as quantified by the time-normalized IL-6 exposure, which was calculated for each individual by dividing the total exposure (AUC) by time (t). A Bonferroni corrected P < 0.017 indicated a significant correlation. RESULTS: Plasma and CSF IL-6 concentrations increased postoperatively. The median [interquartile range] IL-6 exposures were significantly higher in the open vs endovascular surgical group for plasma (105 [40-256] pg·mL-1 vs 29 [16-70] pg·mL-1, respectively; P = 0.013) and CSF (79 [26-133] pg·mL-1 vs 16 [9-80] pg·mL-1, respectively; P = 0.013). For the primary endpoint, the plasma IL-6 AUC/t did not correlate with the CSF accumulation of morphine (r = -0.009; P = 0.96) or M3G (r = 0.37; P = 0.04) when corrected for surgical procedure, age, and sex. There were insufficient data on CSF concentration to complete the primary analysis for M6G. CONCLUSION: Morphine distribution into the CSF was not significantly altered in patients undergoing thoracic aortic aneurysm repair. This suggests that BBB PGP function may not be affected by the perioperative inflammatory response. TRIAL REGISTRATION: www.clinicaltrials.gov , NCT 00878371. Registered 7 April 2009.

CMKLR1 activation ex vivo does not increase proportionally to serum total chemerin in obese humans.

Prochemerin is the inactive precursor of the adipokine chemerin. Proteolytic processing is obligatory for the conversion of prochemerin into active chemerin and subsequent regulation of cellular processes via the chemokine-like receptor 1 (CMKLR1). Elevated plasma or serum chemerin concentrations and differential processing of prochemerin have been reported in obese humans. The impact of these changes on CMKLR1 signalling in humans is unknown. The objective of this pilot study was to develop a cellular bioassay to measure CMKLR1 activation by chemerin present in human serum and to characterise how obesity modifies serum activation of CMKLR1 under fasted and fed conditions. Blood samples were collected from control (N = 4, BMI 20-25) and obese (N = 4, BMI >30) female subjects after an overnight fast (n = 2) and at regular intervals (n = 7) following consumption of breakfast over a period of 6 h. A cellular CMKLR1-luminescent reporter assay and a pan-chemerin ELISA were used to determine CMKLR1 activation and total chemerin concentrations, respectively. Serum total chemerin concentration (averaged across all samples) was higher in obese vs control subjects (17.9 ± 1.8 vs 10.9 ± 0.5 nM, P < 0.05), but serum activation of CMKLR1 was similar in both groups. The CMKLR1 activation/total chemerin ratio was lower in obese vs control subjects (0.33 ± 0.04 vs 0.58 ± 0.05, P < 0.05). After breakfast, serum total chemerin or CMKLR1 activation did not differ from baseline values. In conclusion, the unexpected observation that obese serum activation of CMKLR1 did not match increased total chemerin concentrations suggests impaired processing to and/or enhanced degradation of active chemerin in serum of obese humans.

The Effects of CKD on Cytochrome P450-Mediated Drug Metabolism.

CKD affects a significant proportion of the world's population, and the prevalence of CKD is increasing. Standard practice currently is to adjust the dose of renally eliminated medications as kidney function declines in effort to prevent adverse drug reactions. It is increasingly becoming recognized that CKD also impacts nonrenal clearance mechanisms such as hepatic and intestinal cytochrome P450 (CYP) enzymes and drug transport proteins, the latter of which is beyond the scope of this review. CYPs are responsible for the metabolism of many clinically used drugs. Genetics, patient factors (eg, age and disease) and drug interactions are well known to affect CYP metabolism resulting in variable pharmacokinetics and responses to medications. There now exists an abundance of evidence demonstrating that CKD can impact the activity of many CYP isoforms either through direct inhibition by circulating uremic toxins and/or by reducing CYP gene expression. Evidence suggests that reductions in CYP metabolism in ESRD are reversed by kidney transplantation and temporarily restored via hemodialysis. This review summarizes the current understanding of the effects that CKD can have on CYP metabolism and also discusses the impact that CYP metabolism phenotypes can have on the development of kidney injury.

Biliopancreatic diversion with duodenal switch modifies plasma chemerin in early and late post-operative periods.

OBJECTIVE: Bariatric surgery remains the most effective treatment for obesity and metabolic syndrome. Surgical benefit arises from early-phase resolution of hyperglycemia and late-phase weight loss. The adipokine chemerin is of interest given its roles in immunity, adipogenesis, and metabolism. The study objective was to examine the effects of biliopancreatic diversion with duodenal switch (BPD-DS) on plasma chemerin in the early and late post-operative stages. METHODS: 83 adults with obesity undergoing BPD-DS, 45 obese non-surgical controls, and 9 lean surgical controls were enrolled. Plasma parameters and anthropometric measures were obtained at baseline and at, early (24 h, 5 D) and late (6 months and 12 months) post-operative stages. RESULTS: Plasma chemerin dropped from 176±49 ng/mL at baseline to 132±52 ng/mL 24 h after BPD-DS, rebounded to 200±66 ng/mL after 5 D, and declined to 124±51 and 110±34 ng/mL after 6 and 12 months. Plasma chemerin correlated negatively with measures of inflammation and hepatic injury and positively with measures of obesity, metabolic syndrome, and inflammation in the early and late post-operative periods, respectively. CONCLUSIONS: Chemerin has a novel role in surgical injury but not hyperglycemia resolution early after BPD-DS. Over the long term, plasma chemerin declines to a new set point that is partially determined by body fat reductions.