Risk Factors for Incident Polycystic Ovary Syndrome Diagnosis.

Objective: While highly prevalent, risk factors for incident polycystic ovary syndrome (PCOS) are poorly delineated. Using a population-based cohort, we sought to identify predictors of incident PCOS diagnosis. Materials and Methods: A matched case-control analysis was completed utilizing patients enrolled in Kaiser Permanente Washington from 2006 to 2019. Inclusion criteria included female sex, age 16-40 years, and ≥3 years of prior enrollment with ≥1 health care encounter. PCOS cases were identified using International Classification of Diseases codes. For each incident case (n = 2,491), 5 patients without PCOS (n = 12,455) were matched based on birth year and enrollment status. Potential risk factors preceding diagnosis included family history of PCOS, premature menarche, parity, race, weight gain, obesity, valproate use, metabolic syndrome, epilepsy, prediabetes, and types 1 and 2 diabetes. Potential risk factors for incident PCOS diagnosis were assessed with univariate and multivariable conditional logistic regressions. Results: Mean age of PCOS cases was 26.9 years (SD 6.8). PCOS cases, compared with non-PCOS, were more frequently nulliparous (70.9% versus 62.4%) and in the 3 years prior to index date were more likely to have obesity (53.8% versus 20.7%), metabolic syndrome (14.5% versus 4.3%), prediabetes (7.4% versus 1.6%), and type 2 diabetes (4.1% versus 1.7%) (p < 0.001 for all comparisons). In multivariable models, factors associated with higher risk for incident PCOS included the following: obesity (compared with nonobese) Class I-II (body-mass index [BMI], 30-40 kg/m2; odds ratio [OR], 3.8; 95% confidence interval [CI], 3.4-4.2), Class III (BMI > 40 kg/m2; OR, 7.5, 95% CI, 6.5-8.7), weight gain (compared with weight loss or maintenance) of 1-10% (OR, 1.7, 95% CI, 1.3-2.1), 10-20% (OR, 1.9; 95% CI, 1.5-2.4), and >20% (OR, 2.6; 95% CI, 1.9-3.6), prediabetes (OR, 2.7; 95% CI, 2.1-3.4), and metabolic syndrome (OR, 1.8: 95% CI, 1.5-2.1). Conclusion: Excess weight gain, obesity, and metabolic dysfunction may play a key role in the ensuing phenotypic expression of PCOS. Treatment and prevention strategies targeted at preventing weight gain in early reproductive years may help reduce the risk of this syndrome.

Hepatotoxicity of AKR1C3 Inhibitor BAY1128688: Findings from an Early Terminated Phase IIa Trial for the Treatment of Endometriosis.

INTRODUCTION: BAY1128688 is a selective inhibitor of aldo-keto reductase family 1 member C3 (AKR1C3), an enzyme implicated in the pathology of endometriosis and other disorders. In vivo animal studies suggested a potential therapeutic application of BAY1128688 in treating endometriosis. Early clinical studies in healthy volunteers supported the start of phase IIa. OBJECTIVE: This manuscript reports the results of a clinical trial (AKRENDO1) assessing the effects of BAY1128688 in adult premenopausal women with endometriosis-related pain symptoms over a 12-week treatment period. METHODS: Participants in this placebo-controlled, multicenter phase IIa clinical trial (NCT03373422) were randomized into one of five BAY1128688 treatment groups: 3 mg once daily (OD), 10 mg OD, 30 mg OD, 30 mg twice daily (BID), 60 mg BID; or a placebo group. The efficacy, safety, and tolerability of BAY1128688 were investigated. RESULTS: Dose-/exposure-dependent hepatotoxicity was observed following BAY1128688 treatment, characterized by elevations in serum alanine transferase (ALT) occurring at around 12 weeks of treatment and prompting premature trial termination. The reduced number of valid trial completers precludes conclusions regarding treatment efficacy. The pharmacokinetics and pharmacodynamics of BAY1128688 among participants with endometriosis were comparable with those previously found in healthy volunteers and were not predictive of the subsequent ALT elevations observed. CONCLUSIONS: The hepatotoxicity of BAY1128688 observed in AKRENDO1 was not predicted by animal studies nor by studies in healthy volunteers. However, in vitro interactions of BAY1128688 with bile salt transporters indicated a potential risk factor for hepatotoxicity at higher doses. This highlights the importance of in vitro mechanistic and transporter interaction studies in the assessment of hepatoxicity risk and suggests further mechanistic understanding is required. CLINICAL TRIAL REGISTRATION: NCT03373422 (date registered: November 23, 2017).

Novel aldo-keto reductase 1C3 inhibitor affects androgen metabolism but not ovarian function in healthy women: a phase 1 study.

OBJECTIVE: Aldo-keto reductase 1C3 (AKR1C3) has been postulated to be involved in androgen, progesterone, and estrogen metabolism. Aldo-keto reductase 1C3 inhibition has been proposed for treatment of endometriosis and polycystic ovary syndrome. Clinical biomarkers of target engagement, which can greatly facilitate drug development, have not yet been described for AKR1C3 inhibitors. Here, we analyzed pharmacodynamic data from a phase 1 study with a new selective AKR1C3 inhibitor, BAY1128688, to identify response biomarkers and assess effects on ovarian function. DESIGN: In a multiple-ascending-dose placebo-controlled study, 33 postmenopausal women received BAY1128688 (3, 30, or 90 mg once daily or 60 mg twice daily) or placebo for 14 days. Eighteen premenopausal women received 60 mg BAY1128688 once or twice daily for 28 days. METHODS: We measured 17 serum steroids by liquid chromatography-tandem mass spectrometry, alongside analysis of pharmacokinetics, menstrual cyclicity, and safety parameters. RESULTS: In both study populations, we observed substantial, dose-dependent increases in circulating concentrations of the inactive androgen metabolite androsterone and minor increases in circulating etiocholanolone and dihydrotestosterone concentrations. In premenopausal women, androsterone concentrations increased 2.95-fold on average (95% confidence interval: 0.35-3.55) during once- or twice-daily treatment. Note, no concomitant changes in serum 17ß-estradiol and progesterone were observed, and menstrual cyclicity and ovarian function were not altered by the treatment. CONCLUSIONS: Serum androsterone was identified as a robust response biomarker for AKR1C3 inhibitor treatment in women. Aldo-keto reductase 1C3 inhibitor administration for 4 weeks did not affect ovarian function.ClinicalTrials.gov Identifier: NCT02434640; EudraCT Number: 2014-005298-36.

Incidence, prevalence, and trends in polycystic ovary syndrome diagnosis: a United States population-based study from 2006 to 2019.

BACKGROUND: Polycystic ovary syndrome is the most common endocrine disorder in women of reproductive age, yet US incidence estimates do not exist, and prevalence estimates vary widely. OBJECTIVE: A population-based US study estimated the incidence, prevalence, and trends of polycystic ovary syndrome by age, race and ethnicity, and diagnosing provider type. STUDY DESIGN: A retrospective cohort study of patients enrolled in Kaiser Permanente Washington from 2006 to 2019 was conducted. All members identified as female, aged 16 to 40 years with at least 3 years of enrollment and at least 1 healthcare encounter during that time, were eligible for inclusion. Individuals were excluded if they had a history of oophorectomy or hysterectomy. Polycystic ovary syndrome cases were identified using the International Classification of Diseases diagnosis codes (International Classification of Diseases, Ninth Revision, 256.4 or International Classification of Diseases, Tenth Revision, E28.2). Individuals with a polycystic ovary syndrome diagnosis before study entry were excluded from incidence rate estimations. The incidence rates were adjusted by age using direct standardization to the 2010 US census data. Temporal trends in incidence were assessed using weighted linear regression (overall) and Poisson regression (by age, race and ethnicity, and provider type). Prevalent cases were defined as patients with a polycystic ovary syndrome diagnosis at any time before the end of 2019. Medical record review of 700 incident cases diagnosed in 2011-2019 was performed to validate incident cases identified by International Classification of Diseases codes using the Rotterdam criteria. RESULTS: Among 177,527 eligible patients who contributed 586,470 person-years, 2491 incident polycystic ovary syndrome cases were identified. The mean age at diagnosis was 26.9 years, and the mean body mass index was 31.6 kg/m2. Overall incidence was 42.5 per 10,000 person-years; the rates were similar over time but increased in individuals aged 16 to 20 years from 31.0 to 51.9 per 10,000 person-years (P=.01) and decreased among those aged 26 to 30 years from 82.8 to 45.0 per 10,000 person-years (P=.02). A small decreasing temporal trend in incidence rates was only observed among non-Hispanic White individuals (P=.01). The incidence rates by diagnosing provider type varied little over time. Among the 58,241 patients who contributed person-time in 2019, 3036 (5.2%) had a polycystic ovary syndrome International Classification of Diseases diagnosis code; the prevalence was the highest among the Hawaiian and Pacific Islander group (7.6%) followed by Native American and Hispanic groups. Medical record review classified 60% as definite or probable incident, 14% as possible incident, and 17% as prevalent polycystic ovary syndrome. The overall positive predictive value of polycystic ovary syndrome International Classification of Diseases diagnosis code for identifying definite, probable, or possible incident polycystic ovary syndrome was 76% (95% confidence interval, 72%-79%). CONCLUSION: Among a cohort of nonselected females in the United States, we observed stable rates of incident polycystic ovary syndrome diagnoses over time. The incidence of polycystic ovary syndrome was 4- to 5-fold greater than reported for the United Kingdom. The prevalence of polycystic ovary syndrome (5.2%) was almost double before the published US estimates (2.9%) based on the International Classification of Diseases codes. Race and ethnicity and provider type did not seem to have a major impact on temporal rates. Incident diagnoses increased over time in younger and decreased in older age groups, perhaps related to shifting practice patterns with greater awareness among practitioners of the impact of polycystic ovary syndrome on long-term health outcomes and improved prevention efforts. Moreover, increasing obesity rates may be a factor driving the earlier ages at diagnosis.

Science-Based Approach to Harmonize Contraception Recommendations in Clinical Trials and Pharmaceutical Labels.

This review presents a European Federation of Pharmaceutical Industries and Association/PreClinical Development Expert Group (EFPIA-PDEG) topic group consensus on a data-driven approach to harmonized contraception recommendations for clinical trial protocols and product labeling. There is no international agreement in pharmaceutical clinical trial protocols or product labeling on when/if female and/or male contraception is warranted and for how long after the last dose. This absence of consensus has resulted in different recommendations among regions. For most pharmaceuticals, contraception recommendations are generally based exclusively on nonclinical data and/or mechanism. For clinical trials, contraception is the default position and is maintained for women throughout clinical development, whereas appropriate information can justify removing male contraception. Conversely, contraception is only recommended in product labeling when warranted. A base case rationale is proposed for whether or not female and/or male contraception is/are warranted, using available genotoxicity and developmental toxicity data. Contraception is generally warranted for both male and female subjects treated with mutagenic pharmaceuticals. We propose as a starting point that contraception is not typically warranted when the margin is 10-fold or greater between clinical exposure at the maximum recommended human dose and exposure at the no observed adverse effect level (NOAEL) for purely aneugenic pharmaceuticals and for pharmaceuticals that induce fetal malformations or embryo-fetal lethality. Other factors are discussed, including contraception methods, pregnancy testing, drug clearance, options for managing the absence of a developmental toxicity NOAEL, drug-drug interactions, radiopharmaceuticals, and other drug modalities. Overall, we present a data-driven rationale that can serve as a basis for consistent contraception recommendations in clinical trials and in product labeling across regions.

First administration of the Fc-attenuated anti-ß amyloid antibody GSK933776 to patients with mild Alzheimer's disease: a randomized, placebo-controlled study.

OBJECTIVE: To assess the safety, tolerability, pharmacokinetics, and pharmacodynamics of the Fc-inactivated anti-ß amyloid (Aß) monoclonal antibody (mAb) GSK933776 in patients with mild Alzheimer's disease (AD) or mild cognitive impairment (MCI). METHODS: This was a two-part, single blind, placebo-controlled, first-time-in-human (FTIH) study of single (n = 18) and repeat dose (n = 32) intravenous GSK933776 0.001-6 mg/kg (ClinicalTrials.gov: NCT00459550). Additional safety data from an open-label, uncontrolled, single dose study of intravenous GSK933776 1-6 mg/kg (n = 18) are included (ClinicalTrials.gov: NCT01424436). RESULTS: There were no cases of amyloid-related imaging abnormalities-edema (ARIA-E) or -hemorrhage (ARIA-H) after GSK933776 administration in both studies. Three patients across the two studies developed anti-GSK933776 antibodies. Plasma GSK933776 half-life (t1/2) was 10-15 days after repeat dosing. After each of three administrations of GSK933776, plasma levels of total Aß42 and Aß increased whereas plasma levels of free Aß decreased dose dependently; no changes were observed for placebo. For total Aß42 the peak:trough ratio was ≤2 at doses ≥3 mg/kg; for total Aß the ratio was ≤2 at 6 mg/kg. CSF concentrations of Aß showed increases from baseline to week 12 for Aß X-38 (week 12:baseline ratio: 1.65; 95%CI: 1.38, 1.93) and Aß X-42 (week 12:baseline ratio: 1.18; 95%CI: 1.06, 1.30) for values pooled across doses. CONCLUSION: In this FTIH study the Fc-inactivated anti-Aß mAb GSK933776 engaged its target in plasma and CSF without causing brain ARIA-E/H in patients with mild AD or MCI. TRIAL REGISTRATION: ClinicalTrials.gov NCT00459550.

An adaptive design to investigate the effect of ketoconazole on pharmacokinetics of GSK239512 in healthy male volunteers.

This open label drug-drug interaction (DDI) study investigated the effect of a strong CYP3A inhibitor ketoconazole on the PK and safety profile of GSK239512. To mitigate the tolerability concerns of high GSK239512 exposures resulting from CYP3A inhibition, a 2-cohort adaptive design was used to facilitate a stepwise selection of dose levels and subject numbers. In Cohort 1, 6 subjects received a single dose of 20 µg GSK239512 alone and then 10 µg GSK239512 in combination with repeated once daily doses of 400 mg ketoconazole. The results from Cohort 1 demonstrated an approximately 1.5-fold increase in GSK239512 exposure with a good tolerability profile. This led to the adoption of a 3-session option in Cohort 2, in which 16 subjects received sequential single doses of 20 µg GSK239512 alone, 40 µg GSK239512 alone, and a single dose of 40 µg GSK239512 in combination with repeated once daily doses of 400 mg ketoconazole. The 2-cohort adaptive design proved effective in mitigating any potentially significant DDI risk to healthy subjects. Final results showed a 1.3-fold increase in GSK239512 exposure with ketoconazole, suggesting that in vivo metabolism of GSK239512 by CYP3A is unlikely to be the primary route of GSK239512 elimination.

Modulation of ß-amyloid by a single dose of GSK933776 in patients with mild Alzheimer's disease: a phase I study.

INTRODUCTION: In this study, we evaluated the safety and pharmacodynamic effects of the Fc-inactivated anti-ß-amyloid (anti-Aß) monoclonal antibody GSK933776 in patients with mild Alzheimer's disease and mild cognitive impairment. Aß and tau levels were investigated in cerebrospinal fluid (CSF), and the relationship between Aß levels and Aß modulation in plasma was explored. The feasibility of a continuous sampling method using a lumbar catheter was assessed. METHODS: This trial was a phase I, open-label, uncontrolled, single-dose, exploratory experimental medicine study of intravenous GSK933776 at doses of 1 mg/kg, 3 mg/kg or 6 mg/kg (n = 6/group). The time course of plasma and CSF concentrations of GSK933776 and Aß was assessed. Sample size was based on feasibility, and no formal statistical analyses were performed. RESULTS: Following administration of GSK933776 at doses of 1 mg/kg, 3 mg/kg and 6 mg/kg, there were decreases from baseline in CSF Aß1-42 (from 0 to 12 hours) by 22.8 pg/ml (6.2%), 43.5 pg/ml (9.2%) and 60.5 pg/ml (12.5%), respectively. Plasma concentrations of total Aß18-35 and Aß4228-42 increased immediately after infusion and CSF tau concentration increased slightly, but did not significantly change, following administration of all doses of GSK933776. Pharmacokinetics confirmed the presence of GSK933776 in the CSF, which exhibited a dose-response relationship. One patient underwent minor surgery without sequelae following a ruptured lumbar catheter. CONCLUSION: GSK933776 demonstrated pharmacological activity and target engagement in CSF and plasma, and the continuous sampling method via a catheter successfully assessed the Aß changes following single-dose administration of GSK933776. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT01424436. Registered 4 August 2011.

Systemic administration of Abeta mAb reduces retinal deposition of Abeta and activated complement C3 in age-related macular degeneration mouse model.

Age-related macular degeneration (AMD) is a leading cause of legal blindness in the Western world. There are effective treatments for the vascular complications of neo-vascular AMD, but no effective therapies are available for the dry/atrophic form of the disease. A previously described transgenic CFH-gene deficient mouse model, (cfh-/-), shows hallmarks of early AMD. The ocular phenotype has been further analysed to demonstrate amyloid beta (Aß) rich basement membrane deposits associated with activated complement C3. Cfh-/- mice were treated systemically in both prophylactic and therapeutic regimes with an anti-Aß monoclonal antibody (mAb), 6F6, to determine the effect on the cfh-/- retinal phenotype. Prophylactic treatment with 6F6 demonstrated a dose dependent reduction in the accumulation of both Aß and activated C3 deposition. A similar reduction in the retinal endpoints could be seen after therapeutic treatment. Serum Aß levels after systemic administration of 6F6 show accumulation of Aß in the periphery suggestive of a peripheral sink mechanism. In summary, anti-Aß mAb treatment can partially prevent or reverse ocular phenotypes of the cfh-/- mouse. The data support this therapeutic approach in humans potentially modulating two key elements in the pathogenesis of AMD - Aß and activated, complement C3.

Biological response genes after single dose administration of interferon beta-1b to healthy male volunteers.

Treatment with interferon beta-1b (IFNB-1b) is clinically effective in multiple sclerosis patients. However, the mechanism of action is only partially understood, and validated biological response markers are lacking. We assessed IFNB-1b-induced transcriptional changes by microarray technology. Healthy male volunteers received 250 mug IFNB-1b or placebo in a double-blind, randomized controlled trial (n=5 per group). Most transcripts demonstrated peak levels after 6-12 h and returned to baseline after 48 h. We identified 227 differentially regulated genes including novel and previously described markers. This panel may become a valuable tool for development of new IFNB-1b formulations and assessment of clinical drug effects.

VTE Risk assessment - a prognostic Model: BATER Cohort Study of young women.

BACKGROUND: Community-based cohort studies are not available that evaluated the predictive power of both clinical and genetic risk factors for venous thromboembolism (VTE). There is, however, clinical need to forecast the likelihood of future occurrence of VTE, at least qualitatively, to support decisions about intensity of diagnostic or preventive measures. MATERIALS AND METHODS: A 10-year observation period of the Bavarian Thromboembolic Risk (BATER) study, a cohort study of 4337 women (18-55 years), was used to develop a predictive model of VTE based on clinical and genetic variables at baseline (1993). The objective was to prepare a probabilistic scheme that discriminates women with virtually no VTE risk from those at higher levels of absolute VTE risk in the foreseeable future. A multivariate analysis determined which variables at baseline were the best predictors of a future VTE event, provided a ranking according to the predictive power, and permitted to design a simple graphic scheme to assess the individual VTE risk using five predictor variables. RESULTS: Thirty-four new confirmed VTEs occurred during the observation period of over 32,000 women-years (WYs). A model was developed mainly based on clinical information (personal history of previous VTE and family history of VTE, age, BMI) and one composite genetic risk markers (combining Factor V Leiden and Prothrombin G20210A Mutation). Four levels of increasing VTE risk were arbitrarily defined to map the prevalence in the study population: No/low risk of VTE (61.3%), moderate risk (21.1%), high risk (6.0%), very high risk of future VTE (0.9%). In 10.6% of the population the risk assessment was not possible due to lacking VTE cases. The average incidence rates for VTE in these four levels were: 4.1, 12.3, 47.2, and 170.5 per 104 WYs for no, moderate, high, and very high risk, respectively. CONCLUSION: Our prognostic tool - containing clinical information (and if available also genetic data) - seems to be worthwhile testing in medical practice in order to confirm or refute the positive findings of this study. Our cohort study will be continued to include more VTE cases and to increase predictive value of the model.

Bradykinin-induced pulmonary vasoconstriction is time and inducible nitric oxide synthase dependent in a peritonitis sepsis model.

In an isolated perfused lung model, bradykinin induced pulmonary vasoconstriction in rats made septic by the injection of lipopolysaccharide (LPS). To mimic the pathophysiology of sepsis in humans more closely, we investigated pulmonary endothelial injury in a peritonitis model (cecal ligation and perforation; CLP). Male Sprague-Dawley rats were randomly divided into nine groups (n = 6-8). LPS and CLP rats were compared after 6 h with and without treatment with a selective inhibitor of inducible nitric oxide synthase (iNOS), L-N(6)-(1-iminoethyl)-lysine. Time dependency was investigated in CLP-treated rats at 24 h. The pulmonary circulation was isolated and perfused with a constant flow after the rats' tracheas were intubated and ventilated. Bradykinin (1, 3, and 6 microg) was injected, and changes in perfusion pressure were measured. Lungs were harvested for Western blot analysis to determine the role of iNOS in pulmonary endothelial dysfunction. In contrast to CLP 24 h rats, dose-dependent bradykinin-induced pulmonary vasoconstriction was observed in LPS and CLP 6 h rats. Concomitant administration of L-N(6)-(1-iminoethyl)-lysine significantly attenuated this vasoconstriction in both groups. The iNOS protein was expressed in lung homogenates from LPS 6 h and CLP 6 h but not from CLP 24 h rats. Both sepsis models caused bradykinin-induced pulmonary vasoconstriction, with the CLP groups demonstrating a time dependency of this effect. In conjunction with the time-dependent decrease in iNOS protein, the attenuated bradykinin-induced vasoconstriction due to selective iNOS inhibition suggests an important role for iNOS in pulmonary endothelial injury for both sepsis models.

Low-density lipoprotein receptor-related protein interacts with MafB, a regulator of hindbrain development.

The intracellular domain (ICD) of the low-density lipoprotein receptor-related protein (LRP) functionally interacts with adaptor proteins both as an integral part of the receptor polypeptide and after proteolytic release. Identification of such adaptors has been difficult because the ICD is self-activating in conventional transcription factor-based yeast two-hybrid screens. We adopted an alternative screen for the ICD that depends on the activation of the Ras-signaling pathway and uncovered the transcription factor MafB as novel ICD interacting protein. MafB is a regulator of hindbrain segmentation and interacts with the ICD through a leucine zipper domain. The ICD co-localizes with MafB to the nucleus and negatively regulates its transcriptional activity, suggesting a possible role for LRP in brain development.

Functional interaction of megalin with the megalinbinding protein (MegBP), a novel tetratrico peptide repeat-containing adaptor molecule.

Megalin is a member of the LDL receptor gene family that plays an important role in forebrain development and in cellular vitamin D metabolism through endocytic uptake of vitamin D metabolites. Similar to other receptors in this gene family, megalin is believed to functionally interact with intracellular proteins through adaptors that bind to the receptor tail and regulate its endocytic and signal transducing activities. Using yeast two-hybrid screens, we identified a novel scaffold protein with tetratrico peptide repeats, the megalin-binding protein (MegBP) that associates with the receptor. The binding site of MegBP was mapped to an N-terminal region on the receptor tail harboring a proline-rich peptide element. MegBP binding did not block the endocytic activity of the receptor; however, overexpression resulted in cellular lethality. In further screens, we identified proteins that bound to MegBP and thus might be recruited to the megalin tail. MegBP-interacting partners included several transcriptional regulators such as the SKI-interacting protein (SKIP), a co-activator of the vitamin D receptor. These finding suggest a model whereby megalin directly participates in transcriptional regulation through controlled sequestration or release of transcription factors via MegBP.

Expression profiling confirms the role of endocytic receptor megalin in renal vitamin D3 metabolism.

BACKGROUND: The endocytic receptor megalin constitutes the major pathway for clearance of low-molecular weight plasma proteins from the glomerular filtrate into the renal proximal tubules. Furthermore, the receptor has been implicated in a number of other functions in the kidney including uptake and activation of 25-(OH) vitamin D3, calcium and sodium reabsorption as well as signal transduction. METHODS: We used genome-wide expression profiling by microarray technology to detect changes in the gene expression pattern in megalin knockout mouse kidneys and to uncover some of the renal pathways affected by megalin deficiency. RESULTS: Alterations were identified in several (patho)physiologic processes in megalin-deficient kidneys including the renal vitamin D metabolism, transforming growth factor (TGF)-beta1 signal transduction, lipid transport and heavy metal detoxification. Most importantly, changes were detected in the mRNA levels of 25-(OH) vitamin D-24-hydroxylase and 25-(OH) vitamin D-1alpha-hydroxylase as well as strong up-regulation of TGF-beta1 target genes. Both findings indicate plasma vitamin D deficiency and lack of vitamin D signaling in renal tissues. CONCLUSIONS: Expression profiling confirms a crucial role for megalin in renal vitamin D metabolism.

Megalin deficiency offers protection from renal aminoglycoside accumulation.

Aminoglycosides are antibiotics commonly used to treat life-threatening Gram-negative bacterial infections. However, their use is hampered by their severe nephrotoxicity due to accumulation in renal proximal tubules. Several pathways have been implicated in the renal uptake of aminoglycosides including megalin, an endocytic receptor in proximal tubular cells. Here, we have used mouse models with genetic or functional megalin deficiency to explore the contribution of megalin and other pathways to renal aminoglycoside uptake in vivo. We demonstrate that the uptake of aminoglycosides into the kidney directly correlates with renal megalin activity and is completely eliminated in mice lacking the receptor. Thus, our studies provide unequivocal evidence that megalin is the only major pathway responsible for renal aminoglycoside accumulation and that the receptor represents a unique drug target to prevent aminoglycoside-induced nephrotoxicity in patients.