High blood pressure arising from a defect in vascular function.

Hypertension, a major cardiovascular risk factor and cause of mortality worldwide, is thought to arise from primary renal abnormalities. However, the etiology of most cases of hypertension remains unexplained. Vascular tone, an important determinant of blood pressure, is regulated by nitric oxide, which causes vascular relaxation by increasing intracellular cGMP and activating cGMP-dependent protein kinase I (PKGI). Here we show that mice with a selective mutation in the N-terminal protein interaction domain of PKGIalpha display inherited vascular smooth muscle cell abnormalities of contraction, abnormal relaxation of large and resistance blood vessels, and increased systemic blood pressure. Renal function studies and responses to changes in dietary sodium in the PKGIalpha mutant mice are normal. These data reveal that PKGIalpha is required for normal VSMC physiology and support the idea that high blood pressure can arise from a primary abnormality of vascular smooth muscle cell contractile regulation, suggesting a new approach to the diagnosis and therapy of hypertension and cardiovascular diseases.

Histopathologic Characterization of the Expression of Vascular Endothelial Growth Factor in a Case of Retinopathy of Prematurity Treated With Ranibizumab.

PURPOSE: To characterize the expression of vascular endothelial growth factor (VEGF) in a patient with retinopathy of prematurity (ROP) treated with ranibizumab (Case 1) and compare it with a case of ROP without treatment (Case 2), a case of a premature baby without ROP (Case 3), and a case of a baby without history of ROP or prematurity (Case 4). DESIGN: Observational case series. METHODS: The eyes of the deceased babies were removed postmortem and were sent to the Florida Lions Ocular Pathology Laboratory, where they were processed. The specimens were immunostained using an antibody against VEGF. RESULTS: All eyes except for the eyes in Case 4 disclosed positive VEGF staining. Positive staining was present within the nerve fiber layer, inner plexiform layer, and inner and outer nuclear layers and within the spindle-shaped cell population in the vanguard in Case 1. In the posterior pole, positive staining was only observed at the level of the nerve fiber layer. This case also demonstrated less positive staining when compared with Case 2, where positive staining was found within all layers of the retina. CONCLUSION: Less VEGF staining was observed within the retina of the eyes treated with ranibizumab when compared with the VEGF staining in Case 2. This supports the idea that anti-VEGF agents are effective in reducing the amount of VEGF present in the retina. Furthermore, the fact that some expression of VEGF remains in the immature retina after injection supports the idea that anti-VEGF agents can suppress uncontrolled neovascularization without completely blocking the vascular drive for the vascularization of the immature retina.

TGFbeta superfamily signals are required for morphogenesis of the kidney mesenchyme progenitor population.

The TGFbeta superfamily plays diverse and essential roles in kidney development. Gdf11 and Bmp4 are essential for outgrowth and positioning of the ureteric bud, the inducer of metanephric mesenchyme. During nephrogenesis, Bmp7 is required for renewal of the mesenchyme progenitor population. Additionally, in vitro studies demonstrate inhibitory effects of BMPs and TGFbetas on collecting duct branching and growth. Here, we explore the predicted models of TGFbeta superfamily function by cell-specific inactivation of Smad4, a key mediator of TGFbeta signaling. Using a HoxB7cre transgene expressed in ureteric bud and collecting duct, we find that development of the collecting duct is Smad4 independent. By contrast, removal of Smad4 in nephrogenic mesenchyme using the Bmp7(cre/+) allele leads to disorganization of the nephrogenic mesenchyme and impairment of mesenchyme induction. Smad4-deficient metanephric mesenchyme does not display defects in inducibility in LiCl or spinal cord induction assays. However, in situ hybridization and lineage analysis of Smad4 null mesenchyme cells at E11.5 show that the nephrogenic mesenchyme does not aggregate tightly around the ureteric bud tips, but remains loosely associated, embedded within a population of cells expressing markers of both nephrogenic mesenchyme and peripheral stroma. We conclude that the failure of recruitment of nephrogenic mesenchyme leaves a primitive population of mesenchyme at the periphery of the kidney. This population is gradually depleted, and by E16.5 the periphery is composed of cells of stromal phenotype. This study uncovers a novel role for TGFbeta superfamily signaling in the recruitment and/or organization of the nephrogenic mesenchyme at early time-points of kidney development. Additionally, we present conclusive genetic lineage mapping of the collecting duct and nephrogenic mesenchyme.