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Biomedical subjects

Paul M Stewart

Publications and source records attributed to Paul M Stewart.

At least 19 recordsLinked to original sources
PubMed2007

Inhibition of 11beta-hydroxysteroid dehydrogenase type 1 activity in vivo limits glucocorticoid exposure to human adipose tissue and decreases lipolysis.

CONTEXT: The pathophysiological importance of glucocorticoids (GCs) is exemplified by patients with Cushing's syndrome who develop hypertension, obesity, and insulin resistance. At a cellular level, availability of GCs to the glucocorticoid and mineralocorticoid receptors is controlled by the isoforms of 11beta-hydroxysteroid dehydrogenase (11beta-HSD). In liver and adipose tissue, 11beta-HSD1 converts endogenous, inactive cortisone to active cortisol but also catalyzes the bioactivation of the synthetic prednisone to prednisolone. OBJECTIVE: The objective of the study was to compare markers of 11beta-HSD1 activity and demonstrate that inhibition of 11beta-HSD1 activity limits glucocorticoid availability to adipose tissue. DESIGN AND SETTING: This was a clinical study. PATIENTS: Seven healthy male volunteers participated in the study. INTERVENTION: Intervention included carbenoxolone (CBX) single dose (100 mg) and 72 hr of continuous treatment (300 mg/d). MAIN OUTCOME MEASURES: Inhibition of 11beta-HSD1 was monitored using five different mechanistic biomarkers (serum cortisol and prednisolone generation, urinary corticosteroid metabolite analysis by gas chromatography/mass spectrometry, and adipose tissue microdialysis examining cortisol generation and glucocorticoid-mediated glycerol release). RESULTS: Each biomarker demonstrated reduced 11beta-HSD1 activity after CBX administration. After both a single dose and 72 hr of treatment with CBX, cortisol and prednisolone generation decreased as did the urinary tetrahydrocortisol+5alpha-tetrahydrocortisol to tetrahydrocortisone ratio. Using adipose tissue microdialysis, we observed decreased interstitial fluid cortisol availability with CBX treatment. Furthermore, a functional consequence of 11beta-HSD1 inhibition was observed, namely decreased prednisone-induced glycerol release into adipose tissue interstitial fluid indicative of inhibition of GC-mediated lipolysis. CONCLUSION: CBX is able to inhibit rapidly the generation of active GC in human adipose tissue. Importantly, limiting GC availability in vivo has functional consequences including decreased glycerol release.

11-beta-Hydroxysteroid Dehydrogenase Type 1↗
PubMed2006

Depot-specific prostaglandin synthesis in human adipose tissue: a novel possible mechanism of adipogenesis.

Despite the magnitude of the obesity epidemic, the mechanisms that contribute to increases in fat mass and to differences in fat depots are still poorly understood. Prostanoids have been proposed as potent adipogenic hormones, e.g. metabolites of prostaglandin J2 (PGJ2) bind and activate PPARgamma. We hypothesize that an altered expression of enzymes in PGJ2 synthesis may represent a novel pathogenic mechanism in human obesity. We characterized adipose depot-specific expression of enzymes in PGJ2 synthesis, prostaglandin transporter and PPARgamma isoforms. Paired omental and subcutaneous adipose tissue samples were obtained from 26 women undergoing elective abdominal surgery and gene expression examined in whole tissue and cultured preadipocytes using an Affymetrix cDNA microarray technique and validated with quantitative real-time PCR. All enzymes involved in prostaglandin synthesis were expressed in both adipose tissues. Expression of prostaglandin synthase-1 (PGHS1), prostaglandin D synthase (PTGDS), human prostaglandin transporter (hPGT) and PPARgamma2 was higher in OM adipose tissue compared to SC, whereas 17beta-hydroxysteroid dehydrogenase 5 (AKR1C3) showed predominance in SC adipose tissue. In SC adipose tissue, PGHS1 mRNA expression increased with BMI. The differential, depot-specific expression of key enzymes involved in transport, synthesis and metabolism of prostaglandins may have an important impact upon fat cell biology and may help to explain some of the observed depot-specific differences. In addition, the positive correlation between PGHS1 and BMI offers the novel hypothesis that the regulation of PG synthesis may have a role in determining fat distribution in human obesity.

3-Hydroxysteroid Dehydrogenases↗
PubMed2006

Dissociation of serum dehydroepiandrosterone and dehydroepiandrosterone sulfate in septic shock.

CONTEXT: Dehydroepiandrosterone (DHEA) replacement in sepsis has been advocated because of the sepsis-associated decrease in serum DHEA sulfate (DHEAS). However, experimental sepsis in rodents leads to down-regulation of DHEA sulfotransferase, which inactivates DHEA to DHEAS, theoretically resulting in higher DHEA levels. OBJECTIVE: The objective of the study was to test whether serum DHEA and DHEAS are dissociated in septic shock and to determine their association with circulating cortisol in the context of severity of disease and mortality. DESIGN, SETTING, AND PARTICIPANTS: This was a cross-sectional study consisting of 181 patients with septic shock, 31 patients with acute trauma, and 60 healthy controls. MAIN OUTCOME MEASURES: Serum cortisol, DHEA, and DHEAS were measured before and 60 min after ACTH stimulation. RESULTS: Serum cortisol was increased and DHEAS was decreased in both septic shock and trauma patients (all P < 0.001). However, compared with healthy controls, DHEA was significantly increased in sepsis but decreased after trauma (all P < 0.001). In sepsis, neither cortisol nor DHEA increased significantly after ACTH. Most severely ill patients had higher cortisol (P = 0.069) and lower DHEA (P = 0.076) and a significantly higher cortisol to DHEA ratio (P = 0.004). Similarly, the cortisol to DHEA ratio was significantly increased in nonsurvivors of septic shock (P = 0.026), whereas survivors did not differ from controls (P = 0.322). CONCLUSIONS: The observed dissociation of DHEA and DHEAS in septic shock contradicts the previous concept of sepsis-associated DHEA deficiency. Increased DHEA levels may maintain the balance between glucocorticoid- and DHEA-mediated immune and vascular effects. However, most severe disease and mortality is associated with an increased cortisol to DHEA ratio, which may represent a novel prognostic marker in septic shock.

Adrenocorticotropic Hormone↗
PubMed2006

Altered nuclear receptor corepressor expression attenuates vitamin D receptor signaling in breast cancer cells.

PURPOSE: We hypothesized that deregulated corepressor actions, with associated histone deacetylation activity, epigenetically suppressed vitamin D receptor (VDR) responsiveness and drives resistance towards 1alpha,25-dihydroxyvitamin D(3). EXPERIMENTAL DESIGN: Profiling, transcriptional, and proliferation assays were undertaken in 1alpha,25(OH)(2)D(3)-sensitive MCF-12A nonmalignant breast epithelial cells, a panel of breast cancer cell lines, and a cohort of primary breast cancer tumors (n = 21). RESULTS: Elevated NCoR1 mRNA levels correlated with suppressed regulation of VDR target genes and the ability of cells to undergo arrest in G(1) of the cell cycle. A similar increased ratio of corepressor mRNA to VDR occurred in matched primary tumor and normal cells, noticeably in estrogen receptor alpha-negative (n = 7) tumors. 1alpha,25(OH)(2)D(3) resistance in cancer cell lines was targeted by cotreatments with either 1alpha,25(OH)(2)D(3) or a metabolically stable analogue (RO-26-2198) in combination with either trichostatin A (TSA; histone deacetylation inhibitor) or 5-aza-2'-deoxycytidine (DNA methyltransferase inhibitor). Combinations of vitamin D(3) compounds with TSA restored VDR antiproliferative signaling (target gene regulation, cell cycle arrest, and antiproliferative effects in liquid culture) to levels which were indistinguishable from MCF-12A cells. CONCLUSIONS: Increased NCoR1 mRNA is a novel molecular lesion in breast cancer cells, which acts to suppress responsiveness of VDR target genes, resulting in 1alpha,25(OH)(2)D(3) resistance and seems to be particularly associated with estrogen receptor negativity. This lesion provides a novel molecular diagnostic and can be targeted by combinations of vitamin D(3) compounds and low doses of TSA.

Azacitidine↗
PubMed2006

Cortisol metabolism in hypertension.

Corticosteroids are critically involved in blood pressure regulation. Lack of adrenal steroids in Addison's disease causes life-threatening hypotension, whereas glucocorticoid excess in Cushing's syndrome invariably results in high blood pressure. At a pre-receptor level, glucocorticoid action is modulated by 11beta-hydroxysteroid dehydrogenases (11beta-HSDs). 11Beta-HSD1 activates cortisone to cortisol to facilitate glucocorticoid receptor (GR)-mediated action. By contrast, 11beta-HSD2 plays a pivotal role in aldosterone target tissues where it catalyses the opposite reaction (i.e. inactivation of cortisol to cortisone) to prevent activation of the mineralocorticoid receptor (MR) by cortisol. Mutations in the 11beta-HSD2 gene cause a rare form of inherited hypertension, the syndrome of apparent mineralocorticoid excess (AME), in which cortisol activates the MR resulting in severe hypertension and hypokalemia. Ingestion of competitive inhibitors of 11beta-HSD2 such as liquorice and carbenoxolone result in a similar but milder clinical phenotype. Epidemiological data suggests that polymorphic variability in the HSD11B2 gene determines salt sensitivity in the general population, which is a key predisposing factor to adult onset hypertension in some patients. Extrarenal sites of glucocorticoid action and metabolism that might impact on blood pressure include the vasculature and the central nervous system. Intriguingly, increased exposure to glucocorticoids during fetal life promotes high blood pressure in adulthood suggesting an early programming effect. Thus, metabolism and action in many peripheral tissues might contribute to the pathophysiology of human hypertension.

11-beta-Hydroxysteroid Dehydrogenase Type 2↗
PubMed2006

Integration of the metabolic and cardiovascular effects of exercise.

Most of the essays in this volume have adopted a reductionist approach and have focused on the biochemistry either in skeletal muscle or in the vascular wall. There is however a complex interaction between the biochemistry in the endothelium of the microvascular wall, the vascular smooth muscle and the skeletal muscle fibres involving signalling pathways in the three tissues and an intense exchange of signal molecules between them. In the present essay an integrative overview is given of this complex metabolic interaction and the impairments in it that lead to type 2 diabetes and cardiovascular disease.A reduced nitric oxide production by the (micro)vascular endothelium is identified as the key event and is reversible by regular exercise and a reduced calorie intake. The chapter also contains a description of the complex metabolic network controlled by the inducible transcription factor nuclear factor-kappaB, that is activated in more advanced stages of the chronic diseases, and either leads to repair of the microvascular wall or to irreversible damage and the severe complications of end stage cardiovascular disease and type 2 diabetes.

Atherosclerosis↗
PubMed2006

Assessing the HPA axis in patients with pituitary disease: a UK survey.

OBJECTIVE: Assessing the integrity of the hypothalamic-pituitary-adrenal (HPA) axis following pituitary surgery is necessary to determine the requirement for glucocorticoid replacement therapy, but there remains controversy about the optimum way to measure this. DESIGN AND MEASUREMENTS: Postal questionnaire survey among UK endocrinologists to evaluate the current methods used. RESULTS: The response rate was low (81 out of 598 questionnaires mailed), although 85% were consultants. Fifty-five percent measured 9:00 h plasma cortisol in the immediate postoperative phase. Most carried out definitive testing between 4 and 12 weeks: 36% routinely used the insulin tolerance test (ITT), 59% used the short synacthen test (SST). The 30-min cortisol value was used by 67% as a 'pass' when interpreting the results. Others included cortisol measurement at 60 min (17%) or incremental value (7%). For long-term follow-up of patients not rendered ACTH-deficient by surgery, 64% used the SST for patients who had received radiotherapy. If patients had not had radiotherapy, 42% used the SST, whereas 33% did no routine testing unless the patient was symptomatic or there was evidence of tumour recurrence on imaging. If patients were symptomless but 'failed' the chosen test, 28% still treated the patient with glucocorticoid replacement, 38% retested before treatment and 24% recommended glucocorticoid cover for when unwell or 'stressed'. Fifty-six percent used hydrocortisone at doses of 20 mg/day as replacement therapy. CONCLUSION: Thus, assessment of the HPA axis remains controversial. Although the SST is becoming more popular, there is still considerable variation in the interpretation of results and, in particular, the decision of whether or not to treat with lifelong glucocorticoid replacement therapy.

Adrenocorticotropic Hormone↗
PubMed2006

Variants implicated in cortisone reductase deficiency do not contribute to susceptibility to common forms of polycystic ovary syndrome.

OBJECTIVE: There are close phenotypic similarities between cortisone reductase deficiency (CRD), a rare abnormality of cortisone metabolism, and polycystic ovary syndrome (PCOS). As there is evidence that CRD results from digenic mutations involving the genes encoding 11beta-hydroxysteroid dehydrogenase type 1 (HSD11B1) and hexose-6-phosphate dehydrogenase (H6PD), we sought to establish whether CRD-associated variants in these genes, individually or in combination, influence susceptibility to PCOS. DESIGN: Case-control, family-based association and quantitative-trait analyses. PATIENTS: A UK case sample comprising 256 nuclear families ascertained from a PCOS offspring and 213 singleton PCOS cases plus 549 control subjects. MEASUREMENTS: All subjects were genotyped for CRD-related variants in HSD11B1 (rs12086634) and H6PD (rs6688832). Testosterone was measured with an in-house radioimmunoassay using ether extraction and dextran-coated charcoal separation. RESULTS: Case-control analyses revealed no differences in genotype distribution between PCOS and controls for rs12086634 or rs6688832 (both P = 0.84). Three per cent of cases and 2.4% of controls had genotype combinations (three or more variant alleles at the two sites) considered characteristic of CRD (P = 0.73). There were no departures from expectation in the family-based association studies, and no significant associations between genotypes (individually or in combination) and BMI, WHR or testosterone. CONCLUSIONS: The variants in HSD11B1 and H6PD typed, though implicated in causation of CRD, do not influence susceptibility to PCOS. It seems likely that additional variants within these genes are required for the development of CRD.

11-beta-Hydroxysteroid Dehydrogenase Type 1↗
PubMed2006

Differential expression, function and response to inflammatory stimuli of 11beta-hydroxysteroid dehydrogenase type 1 in human fibroblasts: a mechanism for tissue-specific regulation of inflammation.

Stromal cells such as fibroblasts play an important role in defining tissue-specific responses during the resolution of inflammation. We hypothesized that this involves tissue-specific regulation of glucocorticoids, mediated via differential regulation of the enzyme 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1). Expression, activity and function of 11beta-HSD1 was assessed in matched fibroblasts derived from various tissues (synovium, bone marrow and skin) obtained from patients with rheumatoid arthritis or osteoarthritis. 11beta-HSD1 was expressed in fibroblasts from all tissues but mRNA levels and enzyme activity were higher in synovial fibroblasts (2-fold and 13-fold higher mRNA levels in dermal and synovial fibroblasts, respectively, relative to bone marrow). Expression and activity of the enzyme increased in all fibroblasts following treatment with tumour necrosis factor-alpha or IL-1beta (bone marrow: 8-fold and 37-fold, respectively, compared to vehicle; dermal fibroblasts: 4-fold and 14-fold; synovial fibroblasts: 7-fold and 31-fold; all P < 0.01 compared with vehicle). Treatment with IL-4 or interferon-gamma was without effect, and there was no difference in 11beta-HSD1 expression between fibroblasts (from any site) obtained from patients with rheumatoid arthritis or osteoarthritis. In the presence of 100 nmol/l cortisone, IL-6 production--a characteristic feature of synovial derived fibroblasts--was significantly reduced in synovial but not dermal or bone marrow fibroblasts. This was prevented by co-treatment with an 11beta-HSD inhibitor, emphasizing the potential for autocrine activation of glucocorticoids in synovial fibroblasts. These data indicate that differences in fibroblast-derived glucocorticoid production (via the enzyme 11beta-HSD1) between cells from distinct anatomical locations may play a key role in the predeliction of certain tissues to develop persistent inflammation.

11-beta-Hydroxysteroid Dehydrogenase Type 1↗
PubMed2006

Characterisation of the prereceptor regulation of glucocorticoids in the anterior segment of the rabbit eye.

The prereceptor regulation of glucocorticoids (GCs) by 11beta-hydroxysteroid dehydrogenase type-1 (11beta-HSD1), a bidirectional isozyme that interconverts active (cortisol) and inactive (cortisone) GCs, is an established determinant of GC function in tissues such as liver, adipose and bone. Although the therapeutic use of GCs is abundant in ophthalmic practice, where GC interactions with nuclear receptors modulate gene transcription, the prereceptor regulation of endogenous cortisol is not well described in ocular tissues. Recent descriptive studies have localised 11beta-HSD1 to the human corneal epithelium and non-pigmented epithelium (NPE) of the ciliary body, indicating a link to corneal epithelial physiology and aqueous humour production. In this study, we characterise the functional aspects of the autocrine regulation of GCs in the anterior segment of the rabbit eye. Using our in-house generated primary antibody to human 11beta-HSD1, immunohistochemical analyses were performed on paraffin-embedded sections of whole New Zealand white albino rabbits, (NZWAR) eyes. As in human studies, 11beta-HSD1 was localised to the corneal epithelium and the NPE. No staining was seen in the albino 'pigmented' ciliary epithelium. Specific enzyme assays for oxo-reductase (cortisone-->cortisol) and dehydrogenase (cortisol-->cortisone) activity indicated predominant 11beta-HSD1 oxo-reductase activity from both the intact ciliary body tissue (n=12, median 2.1 pmol/mg per h and range 1.25-2.8 pmol/mg per h; P=0.006) and primary cultures of corneal epithelial cells (n=12, median 3.0 pmol/mg per h and range 1.0-7.4 pmol/mg per h, P=0.008) compared with dehydrogenase activity (median 1.0 pmol/mg per h and range 0.5-2.0 pmol/mg per h; median 0.5 pmol/mg per h and range 0.25-1.9 pmol/mg per h respectively). These findings were supported by expression of 11beta-HSD1 protein as visualised by Western blotting of ciliary body tissue and immunocytochemistry of corneal epithelial cells. Reduction of corneal epithelial cell proliferation was seen after primary cultures were co-incubated with cortisol and cortisone. 11beta-HSD1 activity was not demonstrated in naïve conjunctival fibroblasts or corneal stromal keratocytes. Our results indicate that the distribution of 11beta-HSD1 in the rabbit resembles that of the human eye and activates cortisone to cortisol in both corneal and uveal tissues. The NZWAR provides a suitable in vivo model for the further evaluation of 11beta-HSD1 activity in the eye, especially its role in corneal epithelial and ciliary body physiology.

11-beta-Hydroxysteroid Dehydrogenase Type 1↗
PubMed2005

Hexose-6-phosphate dehydrogenase knock-out mice lack 11 beta-hydroxysteroid dehydrogenase type 1-mediated glucocorticoid generation.

The local generation of active glucocorticoid by NADPH-dependent, 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) oxoreductase activity, has emerged as an important factor in regulating hepatic glucose output and visceral adiposity. We have proposed that this NADPH is generated within the endoplasmic reticulum by the enzyme hexose-6-phosphate dehydrogenase. To address this hypothesis, we generated mice with a targeted inactivation of the H6PD gene. These mice were unable to convert 11-dehydrocorticosterone (11-DHC) to corticosterone but demonstrated increased corticosterone to 11-DHC conversion consistent with lack of 11beta-HSD1 oxoreductase and a concomitant increase in dehydrogenase activity. This increased corticosterone clearance in the knock-out mice resulted in a reduction in circulating corticosterone levels. Our studies define the critical requirement of hexose-6-phosphate dehydrogenase for 11beta-HSD1 oxoreductase activity and add a new dimension to the investigation of 11beta-HSD1 as a therapeutic target in patients with the metabolic syndrome.

11-beta-Hydroxysteroid Dehydrogenase Type 1↗
PubMed2005

The long-term predictive accuracy of the short synacthen (corticotropin) stimulation test for assessment of the hypothalamic-pituitary-adrenal axis.

CONTEXT: The high-dose short Synacthen (corticotropin) test (SST) is widely used to investigate suspected secondary adrenal insufficiency, but concern remains about falsely reassuring results. OBJECTIVE: Our objective was to evaluate the long-term safety of the SST. METHOD: We retrospectively evaluated the clinical outcome in 178 patients who achieved 30-min cortisol values in the lowest 15th percentile of normal healthy responses. Thirty patients were later excluded because of missing case notes (20 patients) or unsubstantiated pituitary pathology (10 patients). The remaining 148 patients were divided into two groups: group 1, patients with cortisol response between the 5th and 15th percentiles of normal response (551-635 nmol/liter, 98 patients); and group 2, patients with borderline response between the 2.5th and 5th percentiles (510-550 nmol/liter, 50 patients). Patients did not receive routine glucocorticoid therapy, but those in group 2 were advised to take hydrocortisone in case of intercurrent illness. RESULTS: The median follow-up period from the initial SST was 4.2 yr (range, 4 months to 7 yr). A total of 137 patients showed no clinical or biochemical evidence of adrenal insufficiency during follow-up. Of the remaining 11 patients, seven became hypoadrenal after subsequent pituitary surgery or radiotherapy, one patient in group 1 developed adrenal insufficiency at 2 yr, and one patient in group 2 developed adrenal insufficiency at 6 months. The other two patients who were in group 2 had clinical diagnostic uncertainty. CONCLUSION: The high-dose SST is safe for the purpose of excluding clinically significant secondary adrenal insufficiency and is indicated as the first line of investigation for this purpose.

Adenoma↗
PubMed2005

Androgen receptor-mediated regulation of the alpha-subunit of the epithelial sodium channel in human kidney.

Rodents studies suggest that androgens are involved in sex-specific differences in blood pressure. In humans, there is no difference in blood pressure between boys and girls, but after puberty, blood pressure increases more in men than in women. We investigated androgen-dependent regulation of the alpha-subunit of the epithelial sodium channel (alphaEnaC) in human kidney and in the human renal cell line immortalized human renal proximal tubular cell line (HKC-8). We used microarray technique to analyze androgen-dependent gene regulation and performed quantitative RT-PCR for verification. Promoter constructs for human alphaENaC were used in transfection studies to analyze the regulation by testosterone. We investigated the in vivo effect of testosterone on alphaENaC in a rat model and used the mouse collecting duct cell line M-1 for transepithelial electrophysiological measurements. The androgen receptor (AR) was expressed in male kidney and HKC-8 cells. AlphaENaC mRNA expression increased 2- to 3-fold after treatment with testosterone in HKC-8 cells. The induction by testosterone was completely blocked by adding the AR antagonist flutamide. Analysis of the alphaENaC promoter sequence identified a putative AR response element (ARE) located 140 nucleotides upstream from the transcription start site. HKC-8 cell transfection studies showed that testosterone directly upregulated gene expression via this ARE. In vivo, testosterone treatment of orchiectomized rats resulted in an increased renal alphaENaC mRNA expression. In testosterone-treated mouse M-1 cells, amiloride caused a significant stronger decrease in short circuit current than in control cells. These data show that alphaENaC expression is directly regulated by androgens in vitro and in vivo and highlight a potential mechanism explaining the reported gender differences in blood pressure.

Animals↗
PubMed2005

Increased expression of mineralocorticoid effector mechanisms in kidney biopsies of patients with heavy proteinuria.

BACKGROUND: Aldosterone has emerged as a deleterious hormone in the heart, with mineralocorticoid receptor (MR) blockade reducing mortality in patients with severe heart failure. There is also experimental evidence that aldosterone contributes to the development of nephrosclerosis and renal fibrosis in rodent models, but little is known of its role in clinical renal disease. METHODS AND RESULTS: We quantified MR, serum- and glucocorticoid-regulated kinase 1 (sgk1), and mRNA expression of inflammatory mediators such as macrophage chemoattractant protein-1 (MCP-1), transforming growth factor-beta1, and interleukin-6 in 95 human kidney biopsies in patients with renal failure and mild to marked proteinuria of diverse etiologic origins. We measured renal function, serum aldosterone, urinary MCP-1 protein excretion, and the amount of chronic renal damage. Macrophage invasion was quantified by CD68 and vascularization by CD34 immunostaining. Serum aldosterone correlated negatively with creatinine clearance (P<0.01) and positively with renal scarring (P<0.05) but did not correlate with MR mRNA expression or proteinuria. Patients with heavy albuminuria (>2 g/24 h; n=15) had the most renal scarring and the lowest endothelial CD34 staining. This group showed a significant 5-fold increase in MR, a 2.5-fold increase in sgk1 expression and a significant increase in inflammatory mediators (7-fold increase in MCP-1, 3-fold increase in transforming growth factor-beta1, and 2-fold increase in interleukin-6 mRNA). Urinary MCP-1 protein excretion and renal macrophage invasion were significantly increased in patients with heavy albuminuria. CONCLUSIONS: These studies support animal data linking aldosterone/MR activation to renal inflammation and proteinuria. Further studies are urgently required to assess the potential beneficial effects of MR antagonism in patients with renal disease.

Adolescent↗
PubMed2005

Sex steroid metabolism in human peripheral blood mononuclear cells changes with aging.

CONTEXT: Dehydroepiandrosterone (DHEA) mainly exerts indirect action via downstream conversion toward sex steroids within peripheral target cells including immune cells. In vitro DHEA has been shown to enhance IL-2 release from T lymphocytes, whereas it inhibits IL-6 secretion. Conversely, aging is associated with a decline in both DHEA and IL-2, whereas IL-6 increases. OBJECTIVE: The objective of the study was to investigate age-related differences in expression and functional activity of steroidogenic enzymes involved in downstream conversion of DHEA in peripheral blood mononuclear cells (PBMCs). DESIGN: This study was cross-sectional. PARTICIPANTS/SETTING: Healthy young men (n = 8; age range, 23-29 yr) and healthy middle-aged men (n = 8; age range, 52-66 yr) were studied in an academic setting. MEASURES: mRNA expression of steroidogenic enzymes in PBMCs was measured by qualitative and quantitative RT-PCR analysis and enzyme activity assays after incubation of PBMCs with radiolabeled DHEA, 4-androstene-3,17-dione (androstenedione), and testosterone. RESULTS: RT-PCR analysis showed expression of all enzymes required for DHEA conversion toward active androgens and to the immune-stimulatory metabolite androstenediol. Steroid conversion patterns indicated a particularly increased activity of 17beta-hydroxysteroid dehydrogenase type 5 (17beta-HSD5) in the older men, demonstrated by significantly higher conversion rates of DHEA to androstenediol and of androstenedione to testosterone (all P < 0.05). By contrast, conversion of DHEA to androstenedione via 3beta-HSD occurred at a similar rate. Quantitative RT-PCR analysis revealed increased expression of 17beta-HSD 5 mRNA in PBMCs from the older men. CONCLUSIONS: Our results provide evidence for significant changes in sex steroid metabolism by human PBMCs with aging, which may represent an endocrine link to immune senescence.

17-Hydroxysteroid Dehydrogenases↗
PubMed2005

Expression profiles for steroidogenic enzymes in adrenocortical disease.

CONTEXT: Excess production of aldosterone or cortisol has profound effects on cardiovascular function and impacts other major organ systems. The mechanisms leading to the autonomous hypersecretion of aldosterone or cortisol in aldosterone-producing adenoma (APA) or cortisol-producing adenoma (CPA) are unknown. OBJECTIVE: The objective of this study was to compare the expression profiles of several steroid-metabolizing enzymes and transcription factors from normal adrenal (NA), APAs, and CPAs. DESIGN: RNA from NAs, APAs, and CPAs were analyzed by microarray and real-time RT-PCR. SETTING: This study was performed at academic research laboratories. PATIENTS: At least nine normal controls and 12 patients with APA or CPA were studied. INTERVENTION: There was no intervention procedure. MAIN OUTCOME MEASURE: The main outcome measure was the expression of steroidogenic enzymes in adrenocortical disease. RESULTS: A microarray indicated a greater than 3-fold increase in the expression of CYP11B2 (aldosterone synthase) in APA, whereas 11beta-hydroxysteroid dehydrogenase type 2 (HSD11B2) and HSD17B1 had greater than 3-fold increases in expression in CPA compared with NA. Real-time RT-PCR showed that APAs produced higher levels of HSD3B2, CYP21 (21-hydroxylase), and CYP11B2 mRNA, whereas CPAs produced higher levels of CYP11A (cholesterol side-chain cleavage), CYP17 (17alpha-hydroxylase/17-20 lyase), HSD3B2, and CYP11B1 (11beta-hydroxylase) mRNA compared with normal adrenal. Steroidogenic factor-1, DAX-1 (dosage-sensitive sex reversal, adrenal hypoplasia congenita, critical region on the X chromosome gene 1), and GATA-6 were expressed at higher levels in APAs and CPAs, whereas NURR1 was expressed at higher levels in APAs than in CPAs or NAs. CONCLUSION: Elevated production of aldosterone in APAs and of cortisol in CPAs is associated with increased expression of enzymes needed for corticosteroid production along with alterations in transcription factors that enhance the expression of steroid-metabolizing enzymes.

Adenoma↗