Reiko Matsumoto

Antipituitary Antibodies in Patients with Lymphocytic Hypophysitis

Background: Lymphocytic hypophysitis is one of the causes of hypopituitarism, which is considered an autoimmune reaction in the anterior pituitary. Method: We examined antipituitary antibodies in patients with lymphocytic hypophysitis and related diseases by immunoblotting method. Results: Autoantibodies to a 22-kDa human pituitary cytosolic protein were identified in significantly higher frequencies in sera from patients with lymphocytic hypophysitis (11 of 15, 73.3%) and isolated ACTH deficiency (7 of 9, 77.8%) compared with Hashimoto thyroiditis, Basedow’s disease and normal control subjects. Also, reactivity against a 49-kDa human pituitary cytosolic protein was seen in 6 of 15 patients (40%) with lymphocytic hypophysitis. N-terminal amino acid sequences of 22-kDa human and rat pituitary cytosolic protein were FPTIPLSVL and FPAMPLSSLFAN, respectively, suggesting that they are human and rat growth hormone, respectively. The pituitary dysfunction (at least one hormone dysfunction) was observed in 11 of 14 patients. Nine of them (82%) showed 22 kDa antibody but 2 of them (18%) did not. Conclusion: The present study demonstrated that pituitary autoantibodies could be involved in the pathogenesis of lymphocytic hypophysitis and could be a positive marker for the disease.

Regulation of Glucocorticoid Receptor Transcription and Nuclear Translocation during Single and Repeated Immobilization Stress

We have previously reported reduced glucocorticoid receptor (GR) mRNA levels in the hippocampus and hypothalamic paraventricular nucleus (PVN) during repeated immobilization, which is potentially associated with persistent activation of the hypothalamic-pituitary-adrenocortical axis. We used in situ hybridization and Western blot to examine the transcriptional regulation of the GR gene, GR nuclear translocation, and expression of cytosolic heat shock protein 90 (hsp90), a chaperone protein essential for GR nuclear translocation, in the hippocampus, PVN, and anterior pituitary (AP) during single immobilization (sIMO) and the final immobilization on d 7 after daily IMO for 6 days (rIMO). As with GR mRNA, GR heteronuclear RNA levels decreased in the hippocampus and PVN and increased in the AP during sIMO and rIMO, indicating that the GR mRNA levels in these regions were regulated at the transcriptional level. In both sIMO and rIMO, nuclear GR levels were significantly increased in the hippocampus, medial basal hypothalamus (MBH), and AP. However, GR nuclear translocation was reduced in the hippocampus, unchanged in the MBH, and enhanced in the AP during rIMO, as compared with sIMO. Cytosolic hsp90 expression was unchanged in the hippocampus and MBH, whereas it significantly increased in the AP at 30 min during rIMO but not during sIMO. These results suggest that the site-specific changes in GR nuclear translocation during sIMO vs. rIMO are partially linked to hsp90 responses to immobilization. The reduced nuclear translocation of GR in the hippocampus during rIMO may reflect decreased glucocorticoid-mediated negative feedback on the hypothalamic-pituitary-adrenocortical axis.

Exposure to the environmental estrogen bisphenol A differentially modulated estrogen receptor-α and -β immunoreactivity and mRNA in male mouse testis

Abstract We examined the effects of bisphenol A (0.5 μg/ml or 50 μg/ml) in the drinking water on estrogen receptor (ER) α and β proteins and mRNA in the testis of young mice following 8-weeks of oral administration of bisphenol A utilizing immunohistochemistry and semiquantitative reverse transcription polymerase chain reaction amplification (RT-PCR). ERβ was clearly localized in the nuclei of spermatogonia and/or spermatocytes. ERβ immunopositive cell numbers per testis section were significantly decreased in the 50 μg/ml bisphenol A-treated group compared with control and the 0.5 μg/ml bisphenol A-treated group. The number of ERα positive cells in the testis was significantly lower than ERβ positive cells in control group. ERα immunopositive cell numbers per testis section were markedly increased in the 50 μg/ml bisphenol A-treated group compared with the control and the 0.5 μg/ml bisphenol A-treated group. ERβ mRNA expression was significantly decreased in the 50 μg/ml bisphenol A-treated group compared with the control and the 0.5 μg/ml bisphenol A-treated group. In contrast, ERα mRNA expression was markedly increased in the 50 μg/ml bisphenol A-treated group compared with the control and the 0.5 μg/ml bisphenol A-treated group. The existence of ERα and β in the testis suggests that estrogens directly affect germ cells during testicular development and spermatogenesis, and differential modulation of ERα and β in the testis could be involved in the effects of bisphenol A.

Angiotensin II receptor blocker inhibits tumour necrosis factor‐alpha‐induced cell damage in human renal proximal tubular epithelial cells

Aim:  We investigated the effect of angiotensin II (AII) type 1 (AT1) and angiotensin II type 2 (AT2) receptor blockers on tumour necrosis factor alpha (TNF‐α)‐induced cell damage in human renal proximal tubular epithelial cells (RPTEC).

Effects of Angiotensin II Type 1 Receptor Blocker on Albumin-Induced Cell Damage in Human Renal Proximal Tubular Epithelial Cells

Background/Aims: Proteinuria is not merely a marker of chronic nephropathies, but may also be involved in the progression to end-stage renal failure. We investigated the effect of angiotensin II type 1 receptor blockers (ARBs) on albumin-induced cell damage in human renal proximal tubular epithelial cells (RPTEC). Methods: The N-acetyl-β- D-glucosaminidase (NAG) and 8-hydroxy-2′-deoxyguanosine (8-OHdG) levels in the medium after albumin treatment with ARBs were determined by commercially available kits. The levels of p22phox protein in RPTEC were measured using Western blotting after albumin treatment with ARBs. Angiotensin II concentrations in cell media and cell lysates were assayed with a commercially available kit. Results: Human albumin (0.1–10 mg/ml) dose-dependently increased NAG release and olmesartan or valsartan (10–9–10–7 mol/l) showed a significant reduction on albumin (1 mg/ml)-induced NAG release in RPTEC. Albumin treatment (1 mg/ml) showed significant increases in p22phox protein levels in RPTEC and ARBs significantly decreased albumin-induced p22phox protein levels. Significant increases in 8-OHdG levels were observed in the albumin (1 mg/ml)-treated group and ARBs markedly reduced albumin-induced 8-OHdG levels in RPTEC. Human albumin dose-dependently increased angiotensin II concentrations in both cell media and lysates. Conclusion: These observations suggest renal tubular cell-protective properties of ARBs related to decreased oxidative stress during proteinuria.

Modulation of Interleukin-1 Receptors Followed by Endotoxin Lipopolysaccharide Treatment in the Mouse AtT-20 Pituitary Tumor Cell Line

Objective: We have previously reported the characterization and regulation of interleukin-1 (IL-1) receptors utilizing [125I]IL-1 binding assay in male C57BL/6 mice and the mouse AtT-20 pituitary tumor cells. In the present study, we examine IL-1 receptors using an immunoblotting method to further characterize the mechanisms regulating the interactions of IL-1 receptors with endotoxin, lipopolysaccharide (LPS). Methods: We established Western blotting for IL-1 receptors using AtT-20 mouse pituitary tumor cells. Results: Several bands were seen; however, only the 105-kD band was neutralized with a 5-fold excess of IL-1 receptor- blocking peptides, suggesting that this band is specific for IL-1 receptors. Next, we investigated the effect of LPS and IL-1β on IL-1 receptors. Treatment of AtT-20 cells with 0.01 µg/ml of LPS did not affect IL-1 receptors. In contrast, 1 µg/ml of LPS significantly increased IL-1 receptors in AtT-20 cells compared with the control group. In addition, [125I]IL-1β binding was markedly increased followed by 1 µg/ml of LPS. In contrast, 1 nM recombinant human IL-1β significantly decreased IL-1 receptors in AtT-20 cells compared with the control group although treatment of AtT-20 cells with 0.01 nM IL-1β did not affect IL-1 receptors. LPS (0.1 and 1 µg/ml) did not affect IL-1β concentrations in the medium of AtT-20 cell culture. IL-1β concentrations in the homogenates from AtT-20 cells were significantly decreased after 1 µg/ml of LPS treatment but not after 0.01 µg/ml LPS. Conclusions: These data demonstrate that LPS and IL-1β differentially modulate IL-1 receptors in AtT-20 cells and LPS-induced modulation of IL-1 receptors may provide a novel mechanism for the actions of LPS to alter pituitary function during endotoxemia. Additional in vivo studies are necessary to determine the physiological relevance of this in vitro phenomenon.

Possible roles of tumor necrosis factor-α and angiotensin II type 1 receptor on high glucose-induced damage in renal proximal tubular cells

Abstract Recent studies have identified that high glucose-induced renal tubular cell damage. We previously demonstrated that high glucose treatment induced oxidative stress in human renal proximal tubular epithelial cells (RPTECs), and angiotensin II type 1 (AT1) receptor blockers reduce high glucose-induced oxidative stress in RPTEC possibly via blockade of intracellular as well as extracellular AT1 receptor. However, exact roles of tumor necrosis factor (TNF)-α and AT1 receptor on high glucose-induced renal tubular function remain unclear. N-acetyl-beta-glucosaminidase (NAG), concentrations of TNF-α/angiotensin II and p22phox protein levels after high glucose treatment with or without AT1 receptor blocker or thalidomide, an inhibitor of TNF-α protein synthesis, were measured in immortalized human renal proximal tubular epithelial cells (HK2 cells). AT1 receptor knockdown was performed with AT1 receptor small interfering RNA (siRNA). High glucose treatment (30 mM) significantly increased NAG release, TNF-α/angiotensin II concentrations in cell media and p22phox protein levels compared with those in regular glucose medium (5.6 mM). Candesartan, an AT1R blocker, showed a significant reduction on high glucose-induced NAG release, TNF-α concentrations and p22phox protein levels in HK2 cells. In addition, significant decreases of NAG release, TNF-α concentrations and p22phox protein levels in HK2 cells were observed in high glucose-treated group with thalidomide. AT1R knockdown with siRNA markedly reversed high glucose, angiotensin II or TNF-α-induced p22phox protein levels in HK2 cells. TNF-α may be involved in high glucose-induced renal tubular damage in HK2 cells possibly via AT1 receptor signaling.

Contents Vol. 55, 2001

W.F. Blum, Bad Homburg J.-P. Bourguignon, Liège H.G. Burger, Melbourne P.G. Chatelain, Lyon G. Chiumello, Milan P.E. Clayton, Manchester G. Copinschi, Brussels H.J. Degenhart, Rotterdam M.G. Forest, Lyon J. Girard, Basel P.D. Gluckman, Auckland A. Grüters, Berlin Z. Hochberg, Haifa R.P. Kelch, Iowa City, Iowa P.J. Keller, Zurich S.W.J. Lamberts, Rotterdam F. Leidenberger, Hamburg C.J. Migeon, Baltimore, Md. E. Milgrom, Bicêtre J. Müller, Copenhagen (Book Reviews) O.H. Pescovitz, Indianapolis, Ind. D.A. Price, Manchester R.G. Rosenfeld, Portland, Ohio G. Saggese, Pisa M.O. Savage, London S.M. Shalet, Manchester T. Tanaka, Tokyo G. Van Vliet, Montreal R.J. Voutilainen, Kuopio G.A. Werther, Parkville, Australia J.-M. Wit, Leiden M. Zachmann, Zurich