Ryo Morimoto

SLCO4C1 Transporter Eliminates Uremic Toxins and Attenuates Hypertension and Renal Inflammation

Hypertension in patients with chronic kidney disease (CKD) strongly associates with cardiovascular events. Among patients with CKD, reducing the accumulation of uremic toxins may protect against the development of hypertension and progression of renal damage, but there are no established therapies to accomplish this. Here, overexpression of human kidney-specific organic anion transporter SLCO4C1 in rat kidney reduced hypertension, cardiomegaly, and inflammation in the setting of renal failure. In addition, SLCO4C1 overexpression decreased plasma levels of the uremic toxins guanidino succinate, asymmetric dimethylarginine, and the newly identified trans-aconitate. We found that xenobiotic responsive element core motifs regulate SLCO4C1 transcription, and various statins, which act as inducers of nuclear aryl hydrocarbon receptors, upregulate SLCO4C1 transcription. Pravastatin, which is cardioprotective, increased the clearance of asymmetric dimethylarginine and trans-aconitate in renal failure. These data suggest that drugs that upregulate SLCO4C1 may have therapeutic potential for patients with CKD.

Type 5 17β-Hydroxysteroid Dehydrogenase (AKR1C3) Contributes to Testosterone Production in the Adrenal Reticularis

CONTEXT The human adrenal gland produces small amounts of testosterone that are increased under pathological conditions. However, the mechanisms through which the adrenal gland produces testosterone are poorly defined. OBJECTIVE Our objective was to define the role of type 5 17beta-hydroxysteroid dehydrogenase (AKR1C3) in human adrenal production of testosterone. DESIGN AND METHODS Adrenal vein sampling was used to confirm ACTH stimulation of adrenal testosterone production. Adrenal expression of AKR1C3 was studied using microarray, quantitative real-time RT-PCR, and immunohistochemical analyses. AKR1C3 knockdown was accomplished in cultured adrenal cells (H295R) using small interfering RNA, followed by measurement of testosterone production. RESULTS Acute ACTH administration significantly increased adrenal vein testosterone levels. Examination of the enzymes required for the conversion of androstenedione to testosterone using microarray analysis, quantitative real-time RT-PCR, and immunohistochemistry demonstrated that AKR1C3 was present in the adrenal gland and predominantly expressed in the zona reticularis. Decreasing adrenal cell expression of AKR1C3 mRNA and protein inhibited testosterone production in the H295R adrenal cell line. CONCLUSIONS The human adrenal gland directly secretes small, but significant, amounts of testosterone that increases in diseases of androgen excess. AKR1C3 is expressed in the human adrenal gland, with higher levels in the zona reticularis than in the zona fasciculata. AKR1C3, through its ability to convert androstenedione to testosterone, is likely responsible for adrenal testosterone production.

Liquid Chromatography–Tandem Mass Spectrometry Analysis of Human Adrenal Vein 19-Carbon Steroids Before and After ACTH Stimulation

CONTEXT A broad analysis of adrenal gland-derived 19-carbon (C19) steroids has not been reported. This is the first study that uses liquid chromatography-tandem mass spectrometry to quantify 9 C19 steroids (androgens and their precursors), estrone, and estradiol in the adrenal vein (AV) of women, before and after ACTH stimulation. OBJECTIVE The objective of this study was to define the adrenal androgen metabolome in women before and after ACTH infusion. DESIGN This was a retrospective study. PATIENTS Seven women, aged 50.4 ± 5.4 years, with suspected diagnosis of an adrenal aldosterone-producing adenoma were included in the study. METHODS AV and iliac serum samples were collected before and after administration of ACTH (15 minutes). AV samples were analyzed using for concentrations of 9 unconjugated C19 steroids, estrone, and estradiol. Dehydroepiandrosterone sulfate (DHEA-S) was quantified by radioimmunoassay. RESULTS AV levels of DHEA-S were the highest among the steroids measured. The most abundant unconjugated C19 steroids in AV were 11β-hydroxyandrostenedione (11OHA), dehydroepiandrosterone (DHEA), and androstenedione (A4). ACTH significantly increased the adrenal output of 9 of the 12 steroids that were measured. ACTH increased the mean AV concentration of DHEA-S by 5-fold, DHEA by 21-fold, A4 by 7-fold, and 11OHA by 5-fold. 11β-Hydroxytestosterone and testosterone were found to be potent androgen receptor agonists when tested with an androgen-responsive cell reporter model. CONCLUSION The current study indicates that the adrenal gland secretes primarily 3 weak androgens, namely DHEA, 11OHA, and A4. Active androgens, including testosterone and 11β-hydroxytestosterone, are also produced but to a lesser degree.

Localization of Aldosterone-Producing Adrenocortical Adenomas: Significance of Adrenal Venous Sampling

Accurate localization of aldosterone-producing adenoma (APA) is essential for the treatment of primary aldosteronism (PA). In order to confirm the clinical usefulness of adrenal venous sampling (AVS), we retrospectively studied 87 cases of PA in whom AVS was conducted. We collected right and left adrenal venous effluents simultaneously before and after adrenocorticotropic hormone (ACTH) stimulation for measurements of aldosterone concentration (A) and cortisol concentration (C). Based on AVS results, we judged 66 cases as having unilateral aldosterone hypersecretion and the remaining 21 cases as having no apparent laterality. Of the above 66 subjects, 61 underwent laparoscopic removal of the adrenal gland through a retroperitoneal approach. The presence of APA was histopathologically confirmed, and blood pressure decreased significantly with normalization of plasma aldosterone concentration (PAC) in all cases. The receiver operator characteristics (ROC) curve analysis between the operated and no–apparent-laterality groups revealed that the ratio of A/C on the higher side to A/C on the lower side (A/C ratio) after ACTH stimulation is a useful index, with a cutoff value of 2.6, a sensitivity of 0.98 and a specificity of 1.0. The ROC curve analysis between the APA side and contralateral side within the operated patients revealed that the cutoff value of A was 1,340 ng/dL, with a sensitivity of 0.92 and a specificity of 1.00. Our results indicate the usefulness of simultaneous AVS and ACTH stimulation for localizing APA.

Outcomes after adrenalectomy for unilateral primary aldosteronism: an international consensus on outcome measures and analysis of remission rates in an international cohort

BACKGROUND Although unilateral primary aldosteronism is the most common surgically correctable cause of hypertension, no standard criteria exist to classify surgical outcomes. We aimed to create consensus criteria for clinical and biochemical outcomes and follow-up of adrenalectomy for unilateral primary aldosteronism and apply these criteria to an international cohort to analyse the frequency of remission and identify preoperative determinants of successful outcome. METHODS The Primary Aldosteronism Surgical Outcome (PASO) study was an international project to develop consensus criteria for outcomes and follow-up of adrenalectomy for unilateral primary aldosteronism. An international panel of 31 experts from 28 centres, including six endocrine surgeons, used the Delphi method to reach consensus. We then retrospectively analysed follow-up data from prospective cohorts for outcome assessment of patients diagnosed with unilateral primary aldosteronism by adrenal venous sampling who had undergone a total adrenalectomy, consecutively included from 12 referral centres in nine countries. On the basis of standardised criteria, we determined the proportions of patients achieving complete, partial, or absent clinical and biochemical success in accordance with the consensus. We then used logistic regression analyses to identify preoperative factors associated with clinical and biochemical outcomes. FINDINGS Consensus was reached for criteria for six outcomes (complete, partial, and absent success of clinical and biochemical outcomes) based on blood pressure, use of antihypertensive drugs, plasma potassium and aldosterone concentrations, and plasma renin concentrations or activities. Consensus was also reached for two recommendations for the timing of follow-up assessment. For the international cohort analysis, we analysed clinical data from 705 patients recruited between 1994 and 2015, of whom 699 also had biochemical data. Complete clinical success was achieved in 259 (37%) of 705 patients, with a wide variance (range 17-62), and partial clinical success in an additional 334 (47%, range 35-66); complete biochemical success was seen in 656 (94%, 83-100) of 699 patients. Female patients had a higher likelihood of complete clinical success (odds ratio [OR] 2·25, 95% CI 1·40-3·62; p=0·001) and clinical benefit (complete plus partial clinical success; OR 2·89, 1·49-5·59; p=0·002) than male patients. Younger patients had a higher likelihood of complete clinical success (OR 0·95 per extra year, 0·93-0·98; p<0·001) and clinical benefit (OR 0·95 per extra year, 0·92-0·98; p=0·004). Higher levels of preoperative medication were associated with lower levels of complete clinical success (OR 0·80 per unit increase, 0·70-0·90; p<0·001). INTERPRETATION These standardised outcome criteria are relevant for the assessment of the success of surgical treatment in individual patients and will allow the comparison of outcome data in future studies. The variable baseline clinical characteristics of our international cohort contributed to wide variation in clinical outcomes. Most patients derive clinical benefit from adrenalectomy, with younger patients and female patients more likely to have a favourable surgical outcome. Screening for primary aldosteronism should nonetheless be done in every individual fulfilling US Endocrine Society guideline criteria because biochemical success without clinical success is by itself clinically important and older women and men can also derive post-operative clinical benefit. FUNDING European Research Council; European Unions Horizon 2020; Else Kröner-Fresenius Stiftung; Netherlands Organisation for Health Research and Development-Medical Sciences; Japanese Ministry of Health, Labour and Welfare; Ministry of Health, Slovenia; US National Institutes of Health; and CONICYT-FONDECYT (Chile).

Effect of adrenocorticotropic hormone stimulation during adrenal vein sampling in primary aldosteronism.

Adrenal vein sampling (AVS) is fundamental for subtype diagnosis in patients with primary aldosteronism. AVS protocols vary between centers, especially for diagnostic indices and for use of adrenocorticotropic hormone (ACTH) stimulation. We investigated the role of both continuous ACTH infusion and bolus on the performance and interpretation of AVS in a sample of 76 patients with confirmed primary aldosteronism. In 36 primary aldosteronism patients, AVS was performed both under basal conditions and after continuous ACTH infusion, and in 40 primary aldosteronism patients, AVS was performed both under basal conditions and after ACTH IV bolus. Both ACTH protocols determined an increase in the rate of successful cannulation of the adrenal veins. Both ACTH infusion and bolus determined a significant increase in selectivity index for the right adrenal vein and ACTH bolus for the left adrenal vein. Lateralization index was not significantly different after continuous ACTH infusion and IV bolus. In 88% and 78% of the patients, the diagnosis obtained was the same before and after ACTH infusion and IV bolus, respectively. However, the reproducibility of the diagnosis was reduced using less stringent criteria for successful cannulation of the adrenal veins. This study shows that ACTH use during AVS may be of help for centers with lower success rates, because a successful adrenal cannulation is more easily obtained with this protocol; moreover, this technique performs at least as well as the unstimulated strategy and in some cases may be even better. Stringent criteria for cannulation should be used to have a high consistency of the diagnosis.

Expression of adrenomedullin2/intermedin in human brain, heart, and kidney

Adrenomedullin2/intermedin (AM2/IMD) is a novel member of the calcitonin/calcitonin gene-related peptide (CGRP) family. In the present study, we developed a specific radioimmunoassay of human AM2/IMD. Expression of AM2/IMD was studied in the human brain, pituitary, heart and kidney obtained at autopsy by radioimmunoassay and immunocytochemistry. Immunoreactive-AM2/IMD was detected by radioimmunoassay in human brains (range; 0.163-1.495 pmol/g wet weight), pituitaries (4.46+/-0.689 pmol/g wet weight, mean+/-S.E.M, n=3), left ventricles of hearts (0.251+/-0.0321 pmol/g wet weight, n=4), kidneys (3.49+/-1.18 pmol/g wet weight, n=5), and plasma obtained at healthy subjects (24.7+/-1.78 pmol/l, n=3). Reverse-phase high performance liquid chromatography showed that immunoreactive-AM2/IMD in human brain, kidney and plasma extracts were eluted in the position of authentic AM2/IMD. Additional peaks eluted earlier were found in the brain tissue and plasma. Immunocytochemistry showed that immunoreactive-AM2/IMD was localized in paraventricular and supraoptic nuclei of hypothalamus, anterior and posterior lobes of pituitary, cardiomyocytes, pericardial adipocytes, vascular endothelial cells of pericardial veins, and vascular smooth muscle cells of coronary arteries and renal arterioles as well as in renal tubular cells. The present study has shown expression of AM2/IMD in various types of cells in the central nervous system and the cardiovascular system, and suggested possible (patho)physiological roles of AM2/IMD in these systems.

Development of sensitive derivatization method for aldosterone in liquid chromatography–electrospray ionization tandem mass spectrometry of corticosteroids

A highly sensitive quantification method of aldosterone by liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) was investigated in a positive mode using recently developed picolinyl derivatization. Aldosterone was smoothly and quantitatively converted to the ethyl ether-picolinyl derivative by treatment with HCl-ethanol followed by the esterification with picolinic acid in the presence of 2-methyl-6-nitrobenzoic anhydride and 4-dimethylaminopyridine. The positive ion-ESI mass spectrum of the ethyl ether-picolinyl derivative was characterized by an appearance of protonated molecule ([M+H](+)) as a base peak. The ethyl ether-picolinyl derivatization gave a successful result in a separation of aldosterone from corticosterone, dehydrocorticosterone and cortexolone, and also provided an approximately 10-fold higher ESI response in the positive-LC-ESI-MS/MS (selected reaction monitoring; SRM) when compared to that of underivatized molecule (negative mode). The limit of quantification of aldosterone by SRM using ethyl ether-picolinyl derivatization (m/z 494-->m/z 448) was 1 pg/0.2 ml serum with accuracy and precision of 92.6% and 5.6%, respectively.

18-Oxocortisol Measurement in Adrenal Vein Sampling as a Biomarker for Subclassifying Primary Aldosteronism

CONTEXT 18-Oxocortisol (18-oxoF) is a derivative of cortisol (F) that is produced by aldosterone synthase (CYP11B2). The potential for this steroid as a biomarker for differentiating patients with aldosterone-producing adenoma (APA) from those with idiopathic hyperaldosteronism (IHA) has not been examined. OBJECTIVES We measured 18-oxoF, aldosterone, and F in plasma from adrenal vein sampling (AVS) of patients with primary aldosteronism. We compared 18-oxoF levels and 18-oxoF/F ratios for their potential to differentiate APA from IHA. DESIGN, SETTING, AND SUBJECTS This study measured 18-oxoF, F, and aldosterone in AVS obtained from patients with unilateral APA (14 cases) or bilateral IHA (seven cases, 14 samples total) using liquid chromatography-tandem mass spectrometry and RIA analyses. RESULTS The levels of 18-oxoF and the ratios of 18-oxoF/F, before and after ACTH stimulation, were significantly higher in blood-draining APA than in those from the contralateral adrenal glands and from adrenal glands with IHA. CONCLUSIONS The 18-oxoF levels and ratios of 18-oxoF/F in AVS samples can be a clinically useful biomarker for differentiating APA from IHA and for determining the localization or lateralization of APA in patients with primary aldosteronism.

Gene expression of (pro)renin receptor is upregulated in hearts and kidneys of rats with congestive heart failure

Recent studies have revealed that (pro)renin receptor ((P)RR), a newly identified member of the renin-angiotensin system, was associated with organ damage in the kidney. However, there has been little information for (P)RR in hearts. To investigate the regulation of (P)RR in heart failure, we examined the expression of (P)RR in hearts and kidneys of rats with congestive heart failure (CHF) due to coronary ligation by quantitative RT-PCR and immunohistochemistry. Significantly increased levels of (P)RR mRNA were found in the atrium, right ventricle, non-infarcted part of left ventricle, infarcted part of left ventricle and kidney of CHF rats, when compared with sham operated rats (about 1.6-fold, 1.4-fold, 1.6-fold, 1.7-fold and 1.5-fold, respectively). Expression levels of mRNAs encoding renin and angiotensinogen in these heart and kidney tissues were also increased in the CHF rats. Immunohistochemistry showed positive (P)RR immunostaining in the myocardium, the renal tubular cells, and vascular smooth muscle and endothelial cells in the heart and the kidney. The renal tubular cells were more intensely immunostained in CHF rats than in sham operated rats. These findings suggest that the expression of (P)RR is increased in the hearts and kidneys of rats with heart failure, and that (P)RR may contribute to heart failure.