Angiotensin II Type 1 Receptor Binding Molecule ATRAP as a Possible Modulator of Renal Sodium Handling and Blood Pressure in Pathophysiology

Exaggerated activation of the renin-angiotensin system via tissue angiotensin II (Ang II) type 1 receptor (AT1R) signaling exerts detrimental effects on cardiovascular, renal and endocrine systems to provoke hypertension and related target organ damage. On the other hand, accumulated research evidence of both basic and clinical studies shows that physiological AT1R signaling also plays an indispensable role for the normal organ development such as the kidney and the maintenance of cardiovascular and renal homeostasis. Such functional diversity of AT1R signaling prompts us to seek a new strategy of selective modulation of AT1R signaling in pathophysiology. In the course of an investigational search for a means to functionally and selectively modulate AT1R signaling for that purpose, a molecule directly interacting with the carboxyl-terminal cytoplasmic domain of AT1R was identified by employing yeast two-hybrid screening of a mouse kidney cDNA library and named AT1R-associated protein (ATRAP). The results of functional analysis showed that ATRAP promotes constitutive AT1R internalization in cultured cells and inhibits Ang II-mediated pathological response in mouse distal convoluted cells. The ATRAP is expressed in a variety of tissues including the kidney where ATRAP is abundantly distributed in epithelial cells along the renal tubules. The results employing genetic engineered mice with modified ATRAP expression showed that ATRAP plays a key role in the regulation of renal sodium handling and the modulation of blood pressure in response to pathological stimuli such as chronic Ang II infusion, and suggest ATRAP to be a target of interest.

P450 oxidoreductase deficiency with maternal virilization during pregnancy

PURPOSE

The authors report on a rare case of maternal virilization during pregnancy caused by autosomal recessive P450 oxidore- ductase (POR) deficiency.

MATERIALS AND METHODS

A 24-year-old primigravida developed a deepening voice and hirsutism in the second trimester. Prenatal ultrasonography failed to detect any fetal abnormality and fetal growth was normal. POR deficiency was suspected, but the mother declined fetal genetic testing. A female neonate was delivered by cesarean section at 41 weeks' gestation.

RESULTS

The neonate had skeletal abnormalities. Mutational analysis of the POR gene demonstrated homozygosity for c.1370 G>A and p.R457H in the patient and heterozygosity in her parents. POR deficiency was confirmed in the neonate.

CONCLUSION

POR deficiency should be suspected in cases of maternal virilization. Maternal urinary estriol, fetal magnetic resonance imaging, and parental genetic testing should be performed. Parental consent for fetal genetic testing should be sought to ensure prompt diagnosis and early treatment.

IL-28B (IFN-λ3) and IFN-α synergistically inhibit HCV replication

Genetic variation in the IL-28B (interleukin-28B; interferon lambda 3) region has been associated with sustained virological response (SVR) rates in patients with chronic hepatitis C treated with peginterferon-α and ribavirin. However, the mechanisms by which polymorphisms in the IL-28B gene region affect host antiviral responses are not well understood. Using the HCV 1b and 2a replicon system, we compared the effects of IFN-λs and IFN-α on HCV RNA replication. The anti-HCV effect of IFN-λ3 and IFN-α in combination was also assessed. Changes in gene expression induced by IFN-λ3 and IFN-α were compared using cDNA microarray analysis. IFN-λs at concentrations of 1 ng/mL or more exhibited concentration- and time-dependent HCV inhibition. In combination, IFN-λ3 and IFN-α had a synergistic anti-HCV effect; however, no synergistic enhancement was observed for interferon-stimulated response element (ISRE) activity or upregulation of interferon-stimulated genes (ISGs). With respect to the time course of ISG upregulation, the peak of IFN-λ3-induced gene expression occurred later and lasted longer than that induced by IFN-α. In addition, although the genes upregulated by IFN-α and IFN-λ3 were similar to microarray analysis, interferon-stimulated gene expression appeared early and was prolonged by combined administration of these two IFNs. In conclusion, IFN-α and IFN-λ3 in combination showed synergistic anti-HCV activity in vitro. Differences in time-dependent upregulation of these genes might contribute to the synergistic antiviral activity.

Human C-reactive protein enhances thrombus formation after neointimal balloon injury in transgenic rabbits

BACKGROUND

High plasma levels of C-reactive protein (CRP) constitute a powerful predictive marker of cardiovascular events. Several lines of evidence suggest that CRP has prothrombogenic effects. However, whether CRP directly participates in the pathogenesis of thrombosis in vivo has not been fully clarified.

OBJECTIVE

To test whether human CRP (hCRP) affects arterial thrombus formation after balloon injury of smooth muscle cell (SMC)-rich or macrophage-rich neointima.

METHODS

We compared the susceptibility of transgenic (Tg) rabbits expressing hCRP (46.21 ± 13.85 mg L(-1), n = 22) and non-Tg rabbits to arterial thrombus formation after balloon injury of SMC-rich or macrophage-rich neointima.

RESULTS

Thrombus size on SMC-rich or macrophage-rich neointima was significantly increased, and was accompanied by an increase in fibrin content in hCRP-Tg rabbits, as compared with non-Tg rabbits. Thrombus size did not significantly differ between SMC-rich and macrophage-rich neointima in hCRP-Tg rabbits. Tissue factor (TF) mRNA expression and activity in these neointimal lesions were significantly increased in hCRP-Tg rabbits as compared with non-Tg rabbits. The degree of CRP deposition correlated with the elevated TF expression and thrombus size on injured neointima. In addition, hCRP isolated from hCRP-Tg rabbit plasma induced TF mRNA expression and activity in rabbit cultured vascular SMCs.

CONCLUSIONS

These results suggest that elevated plasma hCRP levels promote thrombus formation on injured SMC-rich neointima by enhancing TF expression, but have no additive effects in macrophage-rich neointima.

Exercise training reduces PGE2 levels and induces recovery from steatosis in tumor-bearing rats

The effects of endurance training on PGE (2) levels and upon the maximal activity of hepatic carnitine palmitoyltransferase (CPT) system were studied in rats bearing the Walker 256 carciosarcoma. Animals were randomly assigned to a sedentary control (SC), sedentary tumor-bearing (ST), exercised control (EC), and as an exercised tumor-bearing (ET) group. Trained rats ran on a treadmill (60% VO (2) max) for 60 min/day, 5 days/week, for 8 weeks. We examined the mRNA expression (RT-PCR) and maximal activity (radioassay) of the carnitine palmitoyltransferase system enzymes (CPT I and CPT II), as well as the gene expression of fatty-acid-binding protein (L-FABP) in the liver. PGE (2) content was measured in the serum, in tumor cells, and in the liver (ELISA). CPT I and CPT II maximal activity were decreased (p<0.01) in ST when compared with SC. In contrast, serum PGE (2) was increased (p<0.05) in cachectic animals as compared with SC. In the liver, PGE (2) content was also increased (p<0.05) when compared with SC. Endurance training restored maximal CPT I and CPT II activity in the tumor-bearing animals (p<0.0001). Exercise training induced PGE (2) levels to return to control values in the liver of tumor-bearing training rats (p<0.05) and decreased the eicosanoid content in the tumor (p<0.01). In conclusion, endurance training was capable of reestablishing liver carnitine palmitoyltransferase (CPT) system activity associated with decreased PGE (2) levels in cachectic tumor-bearing animals, preventing steatosis.

Disturbed blood flow induces erosive injury to smooth muscle cell-rich neointima and promotes thrombus formation in rabbit femoral arteries

BACKGROUND

Plaque erosion is a cause of atherothrombosis that preferentially occurs on smooth muscle cell (SMC)- and proteoglycan-rich rather than lipid-rich plaques. However, its underlying mechanisms remain unknown.

OBJECTIVE

To determine whether disturbed blood flow induces erosive injury and thrombus formation on SMC-rich neointima.

METHODS

Three weeks after balloon injury, SMC-rich neointima with increased tissue factor (TF) activity developed in rabbit femoral arteries that were narrowed with a vascular occluder to disturb blood flow after stenosis. Neointimal injury and thrombus formation were assessed at 15, 30, and 180 min after the vascular narrowing.

RESULTS

Endothelial detachment, platelet adhesion and neointimal cell apoptosis became evident at the post-stenotic regions of all femoral arteries (n = 5) within 15 min of narrowing. Mural thrombi composed of platelet and fibrin developed after 30 min, and then occlusive thrombi were generated in three out of five vessels after 180 min. The identical vascular narrowing of normal femoral arteries also induced endothelial detachment with small platelet thrombi at post-stenotic regions, but fibrin and occlusive thrombi did not develop. Computational simulation analysis indicated that oscillatory shear stress contributes to the development of erosive damage to the neointima.

CONCLUSIONS

These results suggest that disturbed post-stenotic blood flow can induce erosive injury in SMC-rich plaques and promote thrombus formation that results in vascular events.

Pyranonaphthoquinone lactones: a new class of AKT selective kinase inhibitors alkylate a regulatory loop cysteine

The naturally occurring pyranonaphthoquinone (PNQ) antibiotic lactoquinomycin and related aglycones were found to be selective inhibitors of the serine-threonine kinase AKT. A set of synthetic PNQs were prepared and a minimum active feature set and preliminary SAR were determined. PNQ lactones inhibit the proliferation of human tumor cell lines containing constitutively activated AKT and show expected effects on cellular biomarkers. Biochemical data are presented supporting a proposed bioreductive alkylation mechanism of action.

DNA microarray analyses of genes expressed differentially in 3T3-L1 adipocytes co-cultured with murine macrophage cell line RAW264.7 in the presence of the toll-like receptor 4 ligand bacterial endotoxin

Recent studies have suggested that macrophages were integrated into adipose tissues to interact with adipocytes, thereby exacerbating inflammatory responses. Furthermore, both adipocytes and macrophages appear to express toll-like receptor-4 (TLR-4), and free fatty acids may stimulate cells through TLR-4. Herein, we analyzed genes differentially expressed in adipocytes when co-cultured with macrophages in the presence of a ligand for TLR-4, bacterial lipopolysaccharide (LPS). RAW264.7, a murine macrophage cell line and differentiated 3T3-L1 adipocytes were co-cultured using a transwell system. Genes differentially expressed in adipocytes were analyzed by the DNA microarray method following 4, 8, 12 and 24 h stimulation with 1 ng ml(-1) of Escherichia coli LPS. Randomly selected genes with high expressions were confirmed by quantitative methods at both the gene and the protein level. Co-culture of macrophages and adipocytes with a low LPS concentration (1 ng ml(-1)) markedly upregulated gene expressions associated with inflammation and/or angiogenesis, such as those of interleukin-6 (IL-6), MCP-1, RANTES and CXCL1/KC, in adipocytes. Furthermore, several genes associated with insulin resistance were differentially expressed. Upregulations of genes encoding MCP-1, RANTES and CXC/KC were confirmed by quantitative methods. These results suggest that ligands for TLR-4 stimulate both adipocytes and macrophages to upregulate the expressions of many genes associated with inflammation and/or angiogenesis.

Serotonin induces vasoconstriction of smooth muscle cell-rich neointima through 5-hydroxytryptamine2A receptor in rabbit femoral arteries

BACKGROUND

Smooth muscle cell (SMC)-rich intima is a morphological feature of atherosclerotic lesions that is observed in eroded plaque and spastic arteries. Arteries with SMC-rich intima are susceptible to vasoconstriction or vasospasm against some vasoactive agents.

OBJECTIVE

The present study evaluates the contribution of SMC-rich intima to thrombogenic vasoconstriction.

METHODS

We established SMC-rich neointima by damaging rabbit femoral arteries using balloons and then measured the isometric tension of the femoral strips against 5-hydroxytryptamine (5-HT), adenosine diphosphate, adenosine triphosphate and thrombin.

RESULTS

Among these agents, only 5-HT induced a hypercontractile response of the injured arteries with SMC-rich neointima, compared with non-injured arteries. Smooth muscle cells of both the neointima and media expressed 5-HT(2A) receptor, and sarpogrelate, a selective 5-HT(2A) receptor antagonist significantly inhibited the hypercontraction. Furthermore, 5-HT induced contraction of separated neointima and hypercontraction of separated media compared with non-injured media. Sarpogrelate and fasudil, a specific Rho-kinase inhibitor, significantly suppressed such contraction of both the neointima and media of injured arteries.

CONCLUSIONS

These results suggest that 5-HT plays a crucial role in thrombogenic vasoconstriction, and that SMC-rich intima as well as media directly contributes to the hypercontractile response of atherosclerotic vessels through the 5-HT(2A) receptor and the Rho-kinase pathway.

Medial and adventitial macrophages are associated with expansive atherosclerotic remodeling in rabbit femoral artery

Expansive vascular remodeling is considered a feature of vulnerable plaques. Although inflammation is upregulated in the media and adventitia of atherosclerotic lesions, its contribution to expansive remodeling is unclear. We investigated this issue in injured femoral arteries of normo- and hyperlipidemic rabbits fed with a conventional (CD group; n=20) or a 0.5% cholesterol (ChD group; n=20) diet. Four weeks after balloon injury of the femoral arteries, we examined vascular wall alterations, localization of macrophages and matrix metalloproteases (MMP)-1, -2, -9, and extracellular matrix. Neointimal formation with luminal stenosis was evident in both groups, while expansive remodeling was observed only in the ChD group. Areas immunopositive for macrophages, MMP-1, -2 and -9 were larger not only in the neointima, but also in the media and/or adventitia in the injured arterial walls of the ChD, than in the CD group. Areas containing smooth muscle cells (SMCs), elastin and collagen were smaller in the injured arterial walls of the ChD group. MMP-1, -2 and -9 were mainly localized in infiltrating macrophages. MMP-2 was also found in SMCs and adventitial fibroblasts. Vasa vasorum density was significantly increased in injured arteries of ChD group than in those of CD group. These results suggest that macrophages in the media and adventitia play an important role in expansive atherosclerotic remodeling via extracellular matrix degradation and SMC reduction.

p63(TP63) elicits strong trans-activation of the MFG-E8/lactadherin/BA46 gene through interactions between the TA and DeltaN isoforms

We report here that human MFGE8 encoding milk fat globule-EGF factor 8 protein (MFG-E8), also termed 46 kDa breast epithelial antigen and lactadherin, is transcriptionally activated by p63, or TP63, a p53 (TP53) family protein frequently overexpressed in head-and-neck squamous cell carcinomas, mammary carcinomas and so on. Despite that human MFG-E8 was originally identified as a breast cancer marker, and has recently been reported to provide peptides for cancer immunotherapy, its transcriptional control remains an open question. Observations in immunohistochemical analyses, a tetracycline-induced p63 expression system and keratinocyte cultures suggested a physiological link between p63 and MFGE8. By reporter assays with immediately upstream regions of MFGE8, we determined that the trans-activator (TA) isoforms of p63 activate MFGE8 transcription though a p53/p63 motif at -370, which was confirmed by a chromatin immunoprecipitation experiment. Upon siRNA-mediated p63 silencing in a squamous cell carcinoma line, MFG-E8 production decreased to diminish Saos-2 cell adhesion. Interestingly, the DeltaN-p63 isoform lacking the TA domain enhanced the MFGE8-activating function of TA-p63, if DeltaN-p63 was dominant over TA-p63 as typically observed in undifferentiated keratinocytes and squamous cell carcinomas, implying a self-regulatory mechanism of p63 by the TA:DeltaN association. MFG-E8 may provide a novel pathway of epithelial-nonepithelial cell interactions inducible by p63, probably in pathological processes.

Use of tacrolimus, a potent antifibrotic agent, in bleomycin-induced lung fibrosis

Idiopathic pulmonary fibrosis has a poor prognosis and few efficacious treatments. The immunosuppressant cyclosporin A has been shown to inhibit tumour growth factor (TGF)-beta-induced collagen deposition in vitro, and is widely used in Japan as a potent antifibrotic agent. Tacrolimus (FK506) is another attractive immunosuppressant, which may be useful in the treatment of pulmonary fibrosis. The aim of the present study was to elucidate the antifibrotic effect of FK506. The inhibitory effect of FK506 on collagen synthesis in cultured lung fibroblastic cells, TIG-3-20, and its antifibrotic effect on bleomycin (BLM)-induced pulmonary fibrosis in mice was investigated. FK506 inhibited TGF-beta-induced collagen synthesis, and suppressed the expression of TGF-beta type I receptor (TbetaR-I) in TIG-3-20 cells. Consistent with the in vitro findings, FK506 treatment starting on day 6 attenuated BLM-induced pulmonary fibrosis, in part, via reduced TbetaR-I expression. FK506 treatment in the acute BLM injury phase unexpectedly increased pro-inflammatory cytokine levels in bronchoalveolar lavage fluid and enhanced lung injury, resulting in poor survival. In conclusion, the present results suggest that FK506 has a potent antifibrotic effect and may be useful for the treatment of pulmonary fibrosis, although its use in the acute inflammatory phase may exacerbate lung injury.

The Almodin-Moron trocar for uterine entry during fetal surgery

OBJECTIVE

Compare the use of a newly designed and reusable metal trocar for initial uterine entry with the disposable Tulipan-Bruner trocar in creation of a hysterotomy for fetal surgery.

METHODS

Six consecutive patients undergoing hysterotomy for intrauterine repair of myelomeningocele were randomized to uterine entry either with the Tulipan-Bruner trocar or with the Almodin-Moron trocar. Blood loss was estimated by the primary surgeon.

RESULTS

There was no statistically significant difference in the uterine entry times between the trocars. Blood loss was estimated to be approximately the same. The Almodin-Moron trocar was judged to provide easy handling with good safety.

CONCLUSIONS

The Almodin-Moron trocar provides a uterine entry during creation of a hysterotomy that is as quick and causes as little trauma as the Tulipan-Bruner trocar.