Dysgammaglobulinemia Associated With Glu349del, a Hypomorphic XIAP Mutation.

BACKGROUND: X-linked lymphoproliferative syndrome type 2 is a rare hereditary immunodeficiency caused by mutations in the XIAP gene. This immunodeficiency frequently results in hemophagocytic lymphohistiocytosis, although hypogammaglobulinemia and dysgammaglobulinemia are also common. OBJECTIVE: We identified 17 patients from 12 Japanese families with mutations in XIAP. The Glu349del mutation was observed in 3 patients, each from a different family. Interestingly, these patients exhibited dysgammaglobulinemia but not hemophagocytic lymphohistiocytosis. We conducted an immunological study of patients carrying Glu349del and other mutations to elucidate the pathogenic mechanisms of dysgammaglobulinemia in patients with mutations in the XIAP gene. PATIENTS AND METHODS: We performed an immunological study of 2 patients carrying the Glu349del mutation and 8 patients with other mutations. RESULTS: Flow cytometry showed that the percentage of memory B cells in patients with a mutation in XIAP was lower than that observed in the healthy controls. The patients with the Glu349del mutation had a lower percentage of memory B cells than those with other mutations. Ig production was reduced in patients with the Glu349del mutation. Increased susceptibility to apoptosis was observed in the patients with other mutations. Susceptibility to apoptosis was normal in patients with Glu349del. Microarray analysis indicated that expression of Ig-related genes was reduced in patients with the Glu349del mutation and that the pattern was different from that observed in the healthy controls or patients with other mutations in XIAP. CONCLUSIONS: Patients carrying the Glu349del mutation in the XIAP gene may have a clinically and immunologically distinct phenotype from patients with other XIAP mutations. The Glu349del mutation may be associated with dysgammaglobulinemia.

Dysgammaglobulinemia associated with Glu349del, a hypomorphic XIAP mutation

Antecedentes: El síndrome linfoproliferativo ligado al cromosoma X (XLP) tipo 2, está causado por la mutación del gen XIAP. Se trata de una inmunodeficiencia hereditaria rara. Frecuentemente, los pacientes con XLP2 padecen linfohistiocitosis hemofagocítica (HLH) y disgammaglobulinemia. Objetivo: Se han evaluado diecisiete pacientes japoneses, provenientes de doce familias con mutaciones XIAP y tres pacientes con la mutación Glu349del. Curiosamente, estos últimos pacientes desarrollaron una disgammaglobulinemia pero no HLH. Para dilucidar el fondo patogénico de la disgammaglobulinemia en pacientes con mutación del gen XIAP , se llevó a cabo un estudio inmunológico de estos pacientes. Pacientes y métodos: Pudieron concluir el estudio inmunológico dos pacientes con la mutación Glu349del y ocho pacientes con otras mutaciones. Resultados: Mediante análisis de citometría de flujo se observó que la proporción de linfocitos B de memoria en los pacientes con la mutación XIAP fue menor que la observada en los controles. Los pacientes con la mutación Glu349del tuvieron una menor proporción de linfocitos B de memoria que aquellos con otras mutaciones. Los pacientes con la mutación Glu349del presentaron menor producción de inmunoglobulinas. Los pacientes con la mutación Glu349del mostraron una susceptibilidad normal a la apoptosis, mientras que en los portadores de otras mutaciones se observó una mayor susceptibilidad a la muerte celular. El análisis de microarray indicó que los pacientes con la mutación Glu349del tenían disminuida la expresión de genes relacionados con las inmunoglobulinas y un patrón diferente de la observada en los controles normales o en pacientes con otras mutaciones de genes de XIAP. Conclusiones: Los pacientes portadores de la mutación en el gen Glu349 del XIAP pueden tener un fenotipo clínicamente e inmunológicamente diferente que los pacientes con otras mutaciones XIAP . La mutación Glu349del puede estar asociada con disgammaglobulinemia (AU)

Background: X-linked lymphoproliferative syndrome type 2 is a rare hereditary immunodeficiency caused by mutations in the XIAP gene. This immunodeficiency frequently results in hemophagocytic lymphohistiocytosis, although hypogammaglobulinemia and dysgammaglobulinemia are also common. Objective: We identified 17 patients from 12 Japanese families with mutations in XIAP . The Glu349del mutation was observed in 3 patients, each from a different family. Interestingly, these patients exhibited dysgammaglobulinemia but not hemophagocytic lymphohistiocytosis. We conducted an immunological study of patients carrying Glu349del and other mutations to elucidate the pathogenic mechanisms of dysgammaglobulinemia in patients with mutations in the XIAP gene. Patients and Methods: We performed an immunological study of 2 patients carrying the Glu349del mutation and 8 patients with other mutations. Results: Flow cytometry showed that the percentage of memory B cells in patients with a mutation in XIAP was lower than that observed in the healthy controls. The patients with the Glu349del mutation had a lower percentage of memory B cells than those with other mutations. Ig production was reduced in patients with the Glu349del mutation. Increased susceptibility to apoptosis was observed in the patients with other mutations. Susceptibility to apoptosis was normal in patients with Glu349del. Microarray analysis indicated that expression of Ig-related genes was reduced in patients with the Glu349del mutation and that the pattern was different from that observed in the healthy controls or patients with other mutations in XIAP. Conclusions: Patients carrying the Glu349del mutation in the XIAP gene may have a clinically and immunologically distinct phenotype from patients with other XIAP mutations. The Glu349del mutation may be associated with dysgammaglobulinemia (AU)

Different roles of nitric oxide synthase-1 and -2 between herpetic and postherpetic allodynia in mice.

We investigated using the mice role of nitric oxide synthase (NOS) in the spinal dorsal horn in herpetic and postherpetic pain, especially allodynia, which was induced by transdermal inoculation of the hind paw with herpes simplex virus type-1 (HSV-1). The virus inoculation induced NOS2 expression in the lumbar dorsal horn of mice with herpetic allodynia, but not postherpetic allodynia. There were no substantial alternations in the expression level of NOS1 at the herpetic and postherpetic stages. Herpetic allodynia was significantly inhibited by i.p. administration of the selective NOS2 inhibitor S-methylisothiourea, but not the selective NOS1 inhibitor 7-nitroindazole. NOS2 expression was observed around HSV-1 antigen-immunoreactive cells. On the other hand, postherpetic allodynia was significantly inhibited by i.p. administration of 7-nitroindazole, but not S-methylisothiourea. The activity of reduced nicotinamide adenine dinucleotide phosphate diaphorase, an index of NOS1 activity, significantly increased in the laminae I and II of the lumbar dorsal horn of mice with postherpetic allodynia, but not mice without postherpetic allodynia. The expression level of NOS1 mRNA in the dorsal root ganglia was similar between mice with and without postherpetic allodynia. The results suggest that herpetic and postherpetic allodynia is mediated by nitric oxide in the dorsal horn and that NOS2 and NOS1 are responsible for herpetic and postherpetic allodynia, respectively. It may be worth testing the effects of NOS2 and NOS1 inhibitors on herpetic pain and postherpetic neuralgia in human subjects, respectively.

Induction by carrageenan inflammation of prepronociceptin mRNA in VR1-immunoreactive neurons in rat dorsal root ganglia.

Nociceptin (orphanin FQ) may act on primary afferents and be involved in the regulation of nociceptive processing. We have shown, using reverse transcription-polymerase chain reaction (RT-PCR), that carrageenan-produced peripheral inflammation induces the expression of prepronociceptin (PPN) mRNA in the dorsal root ganglia (DRG). The present experiments were conducted to determine the localization of PPN mRNA in primary sensory neurons after peripheral inflammation, using in situ hybridization. An intraplantar injection of carrageenan induced the expression of PPN mRNA in small and medium sized neurons in the DRG; the effect peaked 0.5 h after carrageenan and subsided by 6 h. All neurons positive for PPN mRNA were positive for vanilloid receptor subtype 1 (VR1)-like immunoreactivity and some VR1-immunoreactive neurons were negative for PPN mRNA. The results suggest that peripheral inflammation induces the production of nociceptin in a sub-population of VR1-positive primary sensory neurons and support the idea that nociceptin produced there is involved in the regulation of nociceptive processing.

Trandolaprilat, an angiotensin-converting enzyme inhibitor, is not excreted in bile via an ATP-dependent active transporter (cMOAT).

Trandolapril is the prodrug of an angiotensin-converting enzyme (ACE) inhibitor. It has been proposed that its active metabolite, trandolaprilat, is mainly excreted in bile, but this has not been clearly demonstrated. Recently it has been reported that temocaprilat, an active metabolite of the ACE inhibitor temocapril, is effectively excreted in bile via an ATP-dependent active transporter (canalicular multispecific organic anion transporter: cMOAT). To investigate whether trandolaprilat has the pharmacological ability to affect the cMOAT system in a manner similar to temocaprilat. The lipophilicity of trandolaprilat and temocaprilat was measured to determine the n-octanol-water partition coefficients. The dose-dependent inhibition of the up-take of [3H]-estradiol-17beta-D-glucuronide and [3H]-2,4-dinitrophenyl-S-glutathione, which are good substrates for cMOAT, in canalicular membrane vesicles (CMVs) prepared from Sprague-Dawley rats was determined in the presence of trandolaprilat and temocaprilat. The partition coefficient of trandolaprilat (log Po/w - 1.1) was about 30 times higher than that of temocaprilat (log Po/w - 2.5). The uptake of [3H]-estradiol-17beta-D-glucuronide and [3H]-2,4-dinitrophenyl-S-glutathione was dose-dependently inhibited by the presence of temocaprilat, but trandolaprilat had no effect on the transport of [3H]-estradiol-17beta-D-glucuronide or [3H]-2,4-dinitrophenyl-S-glutathione into CMVs even at concentrations as high as 200 microM. It could be concluded that trandolaprilat has a higher lipophilicity than temocaprilat. But the hepatobiliary excretion system via cMOAT may not contribute to the excretion of trandolaprilat in bile.

Gabapentin antinociception in mice with acute herpetic pain induced by herpes simplex virus infection.

The effects of systemic and local injections of gabapentin, a novel anticonvulsant agent, were tested on nociceptive behaviors in mice with acute herpetic pain. Transdermal infection with herpes simplex virus type-1 (HSV-1) produced nociceptive hypersensitivity of the infected hind paw to innocuous (allodynia) and noxious mechanical stimulation (hyperalgesia) with von Frey filaments. Systemic administration of gabapentin (10-100 mg/kg, peroral) produced a dose-dependent inhibition of both allodynia and hyperalgesia; gabapentin (30-300 mg/kg) did not affect locomotor activity. Intrathecal injection of gabapentin (10-100 microg/animal) also attenuated dose dependently both nociceptive hypersensitivities. In contrast, intraplantar, intracisternal, and intracerebroventricular administration of gabapentin (10-100 microg/animal) had no effect on the HSV-1-induced nociceptive hypersensitivities. Pretreatment with naltrexone (1 mg/kg) inhibited antinociceptive effect of morphine (5 mg/kg), but not gabapentin (100 mg/kg). Repeated administration of morphine (5 mg/kg, four times) led to tolerance of antinociceptive action, whereas gabapentin (100 mg/kg, four times) had antinociceptive effect even after the forth administration. The present results suggest that gabapentin is effective in the treatment of acute herpetic pain without apparent adverse effects, and analgesic action of gabapentin is mainly mediated by actions on the spinal cord.

Expression of renin-angiotensin system and extracellular matrix genes in cardiovascular cells and its regulation through AT1 receptor.

Angiotensinogen (AGT) is a unique substrate of the renin-angiotensin system and fibronectin (FN) is an important component of the extracellular matrix. These play critical roles in the pathophysiological changes including cardiovascular remodeling and hypertrophy in response to hypertension. This study was performed to examine the regulation of AGT and FN gene in cardiac myocytes (CMs) and vascular smooth muscle cells (VSMCs) in response to mechanical stretch. Mechanical stretch significantly increased the AGT mRNA expression in CMs, while these stimuli did not affect FN mRNA levels. On the other hand, mechanical stretch upregulated FN mRNA levels in VSMCs, whereas no increase in AGT mRNA levels was observed in response to stretch stimuli. An angiotensin II type 1 (AT1) receptor antagonist (CV11974) significantly decreased these stretch-mediated increases in mRNA level and promoter activity of the AGT and FN gene, whereas angiotensin II type 2 (AT2) receptor antagonist (PD 123319) did not affect the induction. These results indicate that mechanical stretch activates transcription of the AGT and FN gene mainly via AT1 receptor-pathway in CMs and VSMCs. Furthermore, mechanisms regulating AGT and FN gene seem to be different between CMs and VSMCs.

Comparison of long-term therapeutic effect of an ACE inhibitor, temocapril, with that of a diuretic on microalbuminuria in non-diabetic essential hypertension.

Many investigators have reported that angiotensin-converting enzyme (ACE) inhibitors have antiproteinuric effects and retard the progression of renal impairment in diabetic patients. On the other hand, those effects of ACE inhibitors have not been well established in patients with essential hypertension. This study was conducted to prospectively evaluate whether an ACE inhibitor, temocapril, could modify the urinary microalbumin excretion rate (UAE) in hypertensive outpatients who had no signs of renal impairment. To compare the long-term effect of temocapril with that of a diuretic on UAE, hypertensive patients treated with a diuretic (trichlormethiazide) were enrolled in a prospective study if they had normal serum creatinine levels and no overt proteinuria during a 3-month screening period. A urinary microalbumin-to-urinary-creatinine ratio (mg albumin/mmol Cr) was used as an estimate of UAE. Patients visited the hospital monthly to determine blood pressure (BP) and UAE. After baseline observation during the treatment with the diuretic, the subjects were randomly divided into two groups. In group A, the diuretic was switched to temocapril, 2 to 4 mg once daily for 12 months. In group B, the subjects continued to receive the diuretic for an additional 12 months. Seventy-six outpatients (41 men and 35 women; mean age, 59.0+/-1.4 years) with essential hypertension entered the study. The effects of temocapril on BP appeared to be clinically similar to those of the trichlormethiazide, but the use of temocapril significantly decreased UAE. In group A (n=37), UAE decreased significantly (p<0.01) from the baseline value of 4.19+/-0.37 mg albumin/mmol Cr to 2.47+/-0.29 and 2.68+/-0.28 mg albumin/mmol Cr at the 6th and 12th month of temocapril therapy, respectively. In contrast, in group B (n=39) UAE was unchanged (baseline, 4.16+/-0.63 mg albumin/mmol Cr; 6 months, 4.92+/-0.72; 12 months, 4.71+/-0.74). These results indicate that long-term therapy with temocapril may be superior in reducing UAE than is diuretic therapy in patients with essential hypertension who had no signs of renal impairment.

Pharmacological and immunohistochemical characterization of a mouse model of acute herpetic pain.

We have recently found that the infection with herpes simplex virus type-1 (HSV-1) of primary sensory neurons induces nociceptive hypersensitivity to noxious mechanical (hyperalgesia) and tactile stimulation (allodynia) in mice. In the present experiments, we determined the distribution of HSV-1 in the dorsal root ganglia and examined the effects of four analgesic agents on hyperalgesia and allodynia. HSV-1 was inoculated on the unilateral shin. HSV-antigen-positive cells were detected in the L4 and L5 dorsal root ganglia on days 5 and 7, but not day 3, post-inoculation. About 80% of the positive cells were small in size. Allodynia and hyperalgesia appeared on day 5 post-inoculation. Antinociceptive effects of analgesic agents were examined on day 6 post-inoculation. Morphine (1-5 mg/kg, subcutaneous) and gabapentin (10-100 mg/kg, peroral) dose-dependently inhibited both allodynia and hyperalgesia. Diclofenac (10-100 mg/kg, intraperitoneal) also produced antinociceptive effects, but there was a ceiling for the effect on hyperalgesia. Amitriptyline (3, 10 mg/kg, subcutaneous) did not affect allodynia and hyperalgesia. The results suggest that mechanical allodynia and hyperalgesia appeared when HSV-1 proliferated in the sensory neurons. This mouse model may be useful for studying the mechanisms of acute herpetic pain and anti-neuropathic pain agents.

Molecular mechanism of fibronectin gene activation by cyclic stretch in vascular smooth muscle cells.

Fibronectin plays an important role in vascular remodeling. A functional interaction between mechanical stimuli and locally produced vasoactive agents is suggested to be crucial for vascular remodeling. We examined the effect of mechanical stretch on fibronectin gene expression in vascular smooth muscle cells and the role of vascular angiotensin II in the regulation of the fibronectin gene in response to stretch. Cyclic stretch induced an increase in vascular fibronectin mRNA levels that was inhibited by actinomycin D and CV11974, an angiotensin II type 1 receptor antagonist; cycloheximide and PD123319, an angiotensin II type 2 receptor antagonist, did not affect the induction. In transfection experiments, fibronectin promoter activity was stimulated by stretch and inhibited by CV11974 but not by PD123319. DNA-protein binding experiments revealed that cyclic stretch enhanced nuclear binding to the AP-1 site, which was partially supershifted by antibody to c-Jun. Site-directed mutation of the AP-1 site significantly decreased the cyclic stretch-mediated activation of fibronectin promoter. Furthermore, antisense c-jun oligonucleotides decreased the stretch-induced stimulation of the fibronectin promoter activity and the mRNA expression. These results suggest that cyclic stretch stimulates vascular fibronectin gene expression mainly via the activation of AP-1 through the angiotensin II type 1 receptor.

Allodynia and hyperalgesia induced by herpes simplex virus type-1 infection in mice.

Human subjects infected with herpes or varicella-zoster viruses complain of pain, such as allodynia, in or near the region with vesicles. However, the mechanisms of the pain are unclear. We show for the first time that infection with herpes simplex virus type-1 (HSV-1) induces allodynia and hyperalgesia in mice. When HSV-1 was inoculated on the hind paw of the mouse, eruption appeared on the back on day 5 post-inoculation, and zosteriform skin lesions were developed on the inoculated side. Allodynia and hyperalgesia became apparent in the hind paw on the inoculated side on day 5 and persisted until at least day 8. HSV-1 DNA was detected in the dorsal root ganglia from days 2 to 8 post-inoculation, with a peak effect on day 5. The application of heat-inactivated HSV-1 induced no allodynia, hyperalgesia and skin lesion. When started from days 0 or 2, repeated treatment with acyclovir, anti-HSV-1 agent, inhibited the appearance of allodynia, hyperalgesia, eruption and the viral proliferation in the dorsal root ganglia. In contrast, when started from days 5 or 6, acyclovir treatment slightly inhibited the development of skin lesions and the viral proliferation, but not allodynia and hyperalgesia. These results suggest that the propagation of HSV-1 in the dorsal root ganglia produces allodynia and hyperalgesia as a result of functional abnormality of the sensory neurons in mice. This may be a useful model for studying the mechanisms of herpetic pain.

Increased circulating vascular endothelial growth factor is correlated with disease activity in polyarticular juvenile rheumatoid arthritis.

OBJECTIVE: To investigate the relevance of vascular endothelial growth factor (VEGF) in the pathogenesis of juvenile rheumatoid arthritis (JRA). METHODS: Serum VEGF levels in 58 patients with JRA (systemic in 17, polyarticular in 29, pauciarticular in 12) were measured by ELISA and compared with those of 21 patients with infectious diseases and 50 healthy children. Correlations of VEGF levels with number of joints with active arthritis, erythrocyte sedimentation rate (ESR), and hyaluronic acid (HA) were examined. RESULTS: Serum levels of VEGF in patients with JRA were significantly higher than in healthy controls. Patients with systemic and polyarticular JRA showed statistically higher levels of VEGF than those with infectious diseases. VEGF levels correlated statistically with C-reactive protein (CRP) in patients with both infectious diseases and polyarticular JRA, but the regression slope (VEGF/CRP) was much steeper in polyarticular JRA than in infectious diseases. Serum VEGF levels correlated with disease activity variables such as the number of joints with active arthritis, ESR, and serum HA levels in polyarticular JRA. CONCLUSION: The correlation of serum VEGF levels and disease activity in polyarticular JRA suggests that VEGF may take an active part in joint inflammation.

Severe hyperparathyroidism with hypercalcemia associated with chronic renal failure at pre-dialysis stage.

We report a case of a 23-year-old Japanese woman who had severe hyperparathyroidism associated with chronic renal failure before the start of dialysis treatment. Her chief complaints were swelling and pain in both shoulders. Laboratory examination revealed renal failure (BUN 134 mg/dl, serum Cr 7.3 mg/dl), severe normocytic normochromic anemia (hemoglobin 4.3 g/dl), hypercalcemia (11.8 mg/dl), and hyperphosphatemia (9.7 mg/dl). Serum PTH levels were extremely increased (intact PTH >1,000 pg/ml: normal range 10-50 pg/ml). X-ray examination of the skull and shoulders showed a salt and pepper appearance, and cauliflower-like deformity of the distal end of both clavicles, respectively. Accelerated ectopic calcification was observed in the costal cartilages, internal carotid arteries, and splenic arteries. Ultrasonographic examination revealed enlargement of the four parathyroid glands. Thallium-technetium subtraction scintigraphy of the parathyroid glands showed increased uptake into the upper two. Renal needle biopsy revealed severe impairment of the interstitium and tubules with much milder changes in glomeruli. The etiology of the renal failure could not be identified. Hemodialysis, total parathyroidectomy and auto-transplantation into the forearm were immediately performed. The pathological diagnosis was chief cell hyperplasia of the parathyroid glands. Based on the presence of chronic renal failure, remarkable hyperphosphatemia with mild hypercalcemia, an unusually high level of serum PTH, and accelerated ectopic calcification, the patient was diagnosed to have severe secondary hyperparathyroidism caused by chronic renal failure with major impairment of the renal interstitium and tubules.

Thrombin receptor mediated signals induce expressions of interleukin 6 and granulocyte colony stimulating factor via NF-kappa B activation in synovial fibroblasts.

OBJECTIVE: To clarify the mechanism of thrombin receptor mediated signal transduction and the induction of cytokines by thrombin stimulation in rheumatoid synovial fibroblasts. METHODS: Cytokines were measured by enzyme linked immunosorbent assay (ELISA) in the supernatants of cultured rheumatoid synovial fibroblasts stimulated by thrombin. To assess the mechanism of thrombin receptor mediated signal transduction in the rheumatoid synovial fibroblasts, electrophoretic mobility gel shift assay (EMSA), immunoglobulin kappa-chloramphenicol acetyltransferase (CAT) assay, and immunostaining for NF-kappa B subunit molecule was performed. RESULTS: Thrombin stimulation activated the inducible transcription factor NF-kappa B, and then induced subsequent expressions of interleukin 6 (IL6) and granulocyte colony stimulating factor (G-CSF) in the cells. CONCLUSION: Thrombin receptor mediated signal transduction could induce the expressions of IL6 and G-CSF, and increase inflammatory events in the cavum articulare via NF-kappa B activation.

Renin-angiotensin system and fibronectin gene expression in Dahl Iwai salt-sensitive and salt-resistant rats.

OBJECTIVE: The tissue renin-angiotensin system and extracellular matrix are involved in the cardiovascular hypertrophy and remodeling induced by hypertension. In this study, we examined the gene expression of the tissue renin-angiotensin system and fibronectin in inbred Dahl Iwai salt-sensitive and salt-resistant rats. MATERIALS AND METHODS: Eight pairs of 6-week-old male Dahl Iwai salt-sensitive and salt-resistant rats were fed either a low- or high-salt diet (0.3% or 8% NaCl, respectively) for 4 weeks. Activities of the circulating renin-angiotensin system were measured by radioimmunoassay and the gene expression of tissue angiotensinogen, the angiotensin II type 1 receptor (AT1) and fibronectin were analyzed by Northern blot analysis. RESULTS: Salt loading significantly increased blood pressure and produced cardiovascular hypertrophy and nephrosclerosis in the salt-sensitive rats. Activities of the circulating renin-angiotensin system were lower in salt-sensitive rats than in salt-resistant rats fed the low-salt diet, and salt loading lowered these activities in salt-resistant rats but not in salt-sensitive rats. In salt-resistant rats, salt loading increased renal, cardiac and aortic angiotensinogen, AT1 and fibronectin messenger (m)RNA expression except for aortic fibronectin mRNA expression. In contrast, in the salt-sensitive rats, salt loading stimulated the expression of cardiac fibronectin and aortic angiotensinogen, AT1 and fibronectin mRNAs. Furthermore, the cardiac and aortic fibronectin mRNA levels in salt-sensitive rats were higher than those in salt-resistant rats when both strains were fed the high-salt diet. CONCLUSIONS: These results demonstrate that the expression of tissue angiotensinogen, AT1 and fibronectin mRNAs is regulated differently in Dahl Iwai salt-sensitive and salt-resistant rats, and indicate that salt-mediated hypertension activates the cardiac fibronectin gene independently of the tissue renin-angiotensin system and stimulates the aortic fibronectin gene with activation of the tissue renin-angiotensin system.

Effects of renin-angiotensin system blockade and dietary salt intake on left ventricular hypertrophy in Dahl salt-sensitive rats.

We studied the effects of chronic blockade of the renin-angiotensin system on hypertension and cardiac left ventricular hypertrophy (LVH) in Dahl salt-sensitive (DS) rats given a high-salt or low-salt diet. [Experiment 1] Twelve-week-old male DS rats were fed an 8% NaCl diet and received the angiotensin II receptor (AT1) antagonist, candesartan (3 mg/kg/d), the angiotensin converting enzyme inhibitor enalapril (30 mg/kg/d), or vehicle for 6 wk after 3 wk of 8% salt-loading. Neither candesartan nor enalapril with concomitant high salt-loading attenuated the blood pressure (BP) elevation. LVH was also not attenuated significantly by these treatments. [Experiment 2] After 8 wk of 8% salt-loading, the rats were given a 0.3% NaCl diet and concurrently received candesartan, enalapril, or vehicle for 5 wk. Switching from the high-salt to low-salt diet significantly decreased BP and left ventricular mass in the vehicle-treated animals. Both candesartan and enalapril normalized BP during salt-depletion; the blockade of the renin-angiotensin system produced an additive reduction in LVH. These findings suggest that sodium intake and hemodynamic load, but not the renin-angiotensin system, may be major determinants of the development of LVH in DS rats.

Mechanism of angiotensin II-mediated regulation of fibronectin gene in rat vascular smooth muscle cells.

This study was performed to investigate a mechanism of angiotensin II (Ang II)-mediated activation of the fibronectin (FN) gene in rat vascular smooth muscle cells. Actinomycin D and CV11974 completely inhibited Ang II-mediated increase in FN mRNA levels. Inhibitors of protein kinase C (PKC), protein-tyrosine kinase (PTK), phosphatidylinositol-specific phospholipase C, Ras, phosphatidylinositol 3-kinase, p70 S6 kinase, and Ca2+/calmodulin kinase also decreased Ang II-induced activation of FN mRNA. In contrast, cycloheximide; PD123319; or inhibitors of Gi, protein kinase A, or mitogen-activated protein kinase kinase did not affect the induction. FN promoter contained a putative AP-1 binding site (rFN/AP-1; -463 to -437), and the results of a transient transfection and electrophoretic mobility shift assay showed that Ang II enhanced rFN/AP-1 activity. CV11974 and inhibitors of PKC or PTK suppressed Ang II-mediated increases in rFN/AP-1 activity, although neither PD123319 nor a protein kinase A inhibitor affected the induction. Furthermore, mutation of rFN/AP-1 that disrupted nuclear binding suppressed Ang II-induced transcription in the native FN promoter (-1908 to +136) context. Thus, Ang II activates transcription of the FN gene through the Ang II type 1 receptor in vascular smooth muscle cells, at least in part, via the activation of AP-1 by a signaling mechanism dependent on PKC and PTK.

Intravascular ultrasound imaging of atherosclerotic renal arteries: comparison between in vitro and in vivo studies.

BACKGROUND: Intravascular ultrasound (IVUS) imaging, a new modality, may be feasible and useful for the assessment of atherosclerotic renal arteries. However, comparison between in vivo and in vitro studies to confirm pathological changes corresponding with IVUS findings obtained from renal arteries was not fully evaluated. METHODS: We evaluated ultrasound images of 18 post-mortem human renal arteries and cross-sectional IVUS images of main renal arteries in five patients with renal artery stenosis (RAS) or essential hypertension. RESULTS: In vitro studies have shown that renal-artery images had three layers when the arteries had fibrous intimal thickening and medial hypertrophy. Renal arteries, in which the fibrous intima was not well developed, showed circumferentially homogeneous bright echoes. In patients with atherosclerotic RAS and essential hypertension, IVUS images showed hyperechoic areas in the renal arterial walls, probably due to atherosclerosis. Typical three-layered ultrasound appearance was not easily seen during in vivo studies. CONCLUSION: Our findings suggest that hyperechoic images can be a diagnostic clue of atherosclerosis However, in vitro results do not always correspond exactly to in vivo findings, and caution is needed when findings from in vitro IVUS imaging studies are applied to in vivo studies.

Long-term therapy with an ACE inhibitor, temocapril, reduces microalbuminuria in essential hypertension.

The present study was conducted to prospectively evaluate whether a new ACE inhibitor, temocapril, could modify urinary microalbumin excretion rate (UAE) in a group of hypertensive outpatients who had no evidence of renal impairment. Sixty-three outpatients (32 men and 31 women; mean age, 59.9 +/- 1.5 yr) with essential hypertension entered the study, all having been treated for at least 6 mo with dihydropyridine calcium-channel blockers (CCBs: nitrendipine, nisoldipine, or amlodipine). Their blood pressures (BPs) had been controlled to adequate levels with the CCBs. None had overt proteinuria (determined by Albustix) or abnormal serum creatinine levels. After 3 mo of baseline observation under the previous treatment, the subjects were randomly divided into two groups. In group A (n = 31), the previously used CCBs were switched to temocapril, 2 to 4 mg once daily for 12 mo, and BP was controlled at a level equivalent to that during CCB treatment. In group B (n = 32), the subjects were maintained on their previous treatment for a further 12 mo. The effect of temocapril on BP appeared to be clinically similar to that of the previously used CCBs, but it significantly decreased UAE as compared with the previous therapy. In group A, UAE decreased significantly (p < 0.01) from the baseline value of 38.9 +/- 5.1 mg/g creatinine (Cr) to 22.2 +/- 4.2 and 25.3 +/- 5.6 mg/g Cr at the 6th and 12th months of temocapril therapy, respectively. In contrast, in group B UAE was unchanged (baseline 39.8 +/- 6.6 mg/g Cr; 6 mo, 44.6 +/- 6.8; 12 mo, 45.9 +/- 7.7). In group A, 17 of 31 patients (54.8%) had abnormal UAE levels (> or = 29.5 mg/g Cr) during previous therapy with CCBs, but 6 mo after switching to temocapril 25 of these patients (80.6%) had normal UAE (< 29.5 mg/g Cr). In group B, 15 of 32 patients (46.9%) had abnormal UAE levels during the observation period, and these abnormal UAE levels remained unchanged; 17 of the 32 patients (53.1%) had abnormal UAE levels after a further 6 mo of continued CCBs therapy. We conclude that long-term therapy with temocapril may provide renal protection by reducing UAE even in hypertensive patients with no evidence of renal impairment.