Increased renal expression of vascular endothelial growth factor (VEGF) and its receptor VEGFR-2 in experimental diabetes

It has been suggested that the cytokine vascular endothelial growth factor (VEGF) has an important role in the pathogenesis of diabetic retinopathy, but its role in nephropathy has not been clearly demonstrated. Assessment of VEGF, 125I-VEGF binding, and vascular endothelial growth factor receptor-2 (VEGFR-2) in the kidney was performed after 3 and 32 weeks of streptozotocin-induced diabetes. Gene expression of both VEGF and VEGFR-2 was assessed by Northern blot analysis and the localization of the ligand and receptor was examined by in situ hybridization. VEGF and VEGFR-2 protein were also evaluated by immunohistochemistry. Binding of the radioligand 125I-VEGF was evaluated by in vitro and in vivo autoradiography. Diabetes was associated with increased renal VEGF gene expression. VEGF mRNA and protein were localized to the visceral epithelial cells of the glomerulus and to distal tubules and collecting ducts in both diabetic and nondiabetic rats. Renal VEGFR-2 mRNA was increased after 3 weeks of diabetes but not in long-term diabetes. In situ hybridization and immunohistochemical studies revealed that glomerular endothelial cells were the major site of VEGFR-2 expression. In addition, VEGFR-2 gene expression was detected in cortical and renomedullary interstitial cells and on endothelial cells of peritubular capillaries. There was an increase in 125I-VEGF binding sites after 3 but not 32 weeks of diabetes. The major VEGF binding sites were in the glomeruli. 125I-VEGF binding was also observed in medullary rays and in the renal papillae. These studies indicate an early and persistent increase in renal VEGF gene expression in association with experimental diabetes. In addition, an early and transient increase in renal VEGF receptors was also observed in diabetic rats. These findings are consistent with a role for VEGF in mediating some of the changes observed in the diabetic kidney.

Attenuation of extracellular matrix accumulation in diabetic nephropathy by the advanced glycation end product cross-link breaker ALT-711 via a protein kinase C-alpha-dependent pathway

This study investigated the role of advanced glycation end products (AGEs) in mediating protein kinase C (PKC) isoform expression in diabetic nephropathy. In vitro, vascular smooth muscle cells incubated in a high-glucose (25-mmol/l) medium demonstrated translocation and increased expression of PKC-alpha as compared with those from a low-glucose (5-mmol/l) environment. Coincubation with the cross-link breaker ALT-711 and, to a lesser extent, with aminoguanidine, an inhibitor of AGE formation, attenuated the increased expression and translocation of PKC-alpha. Streptozotocin-induced diabetic rats were randomized to no treatment, treatment with ALT-711, or treatment with aminoguanidine. Diabetes induced increases in PKC-alpha as well as in the -betaI, -betaII, and -epsilon isoforms. Treatment with ALT-711 and aminoguanidine, which both attenuate renal AGE accumulation, abrogated these increases in PKC expression. However, translocation of phosphorylated PKC-alpha from the cytoplasm to the membrane was reduced only by ALT-711. ALT-711 treatment attenuated expression of vascular endothelial growth factor and the extracellular matrix proteins, fibronectin and laminin, in association with reduced albuminuria. Aminoguanidine had no effect on VEGF expression, although some reduction of fibronectin and laminin was observed. These findings implicate AGEs as important stimuli for the activation of PKC, particularly PKC-alpha, in the diabetic kidney, which can be directly inhibited by ALT-711.

The burden of respiratory syncytial virus in healthy term-born infants in Europe: a prospective birth cohort study

BACKGROUND

Respiratory syncytial virus (RSV) is a major cause of hospitalisation in infants. The burden of RSV infection in healthy term infants has not yet been established. Accurate health-care burden data in healthy infants are necessary to determine RSV immunisation policy when RSV immunisation becomes available.

METHODS

We performed a multicentre, prospective, observational birth cohort study in healthy term-born infants (≥37 weeks of gestation) in five sites located in different European countries to determine the health-care burden of RSV. The incidence of RSV-associated hospitalisations in the first year of life was determined by parental questionnaires and hospital chart reviews. We performed active RSV surveillance in a nested cohort to determine the incidence of medically attended RSV infections. The study is registered with ClinicalTrials.gov, NCT03627572.

FINDINGS

In total, 9154 infants born between July 1, 2017, and April 1, 2020, were followed up during the first year of life and 993 participated in the nested active surveillance cohort. The incidence of RSV-associated hospitalisations in the total cohort was 1·8% (95% CI 1·6-2·1). There were eight paediatric intensive care unit admissions, corresponding to 5·5% of 145 RSV-associated hospitalisations and 0·09% of the total cohort. Incidence of RSV infection in the active surveillance cohort confirmed by any diagnostic assay was 26·2% (24·0-28·6) and that of medically attended RSV infection was 14·1% (12·3-16·0).

INTERPRETATION

RSV-associated acute respiratory infection causes substantial morbidity, leading to the hospitalisation of one in every 56 healthy term-born infants in high-income settings. Immunisation of pregnant women or healthy term-born infants during their first winter season could have a major effect on the health-care burden caused by RSV infections.

FUNDING

Innovative Medicines Initiative 2 Joint Undertaking, with support from the EU's Horizon 2020 research and innovation programme and European Federation of Pharmaceutical Industries and Associations.

Retinal angiogenesis is mediated by an interaction between the angiotensin type 2 receptor, VEGF, and angiopoietin

There is evidence that angiotensin II, vascular endothelial growth factor (VEGF), angiopoietins, and their cognate receptors participate in retinal angiogenesis. We investigated whether angiotensin type 2-receptor blockade (AT2-RB) reduces retinal angiogenesis and alters the expression of VEGF/VEGF-R2 and angiopoietin-Tie2. Retinopathy of prematurity (ROP) was induced in Sprague Dawley (SD) rats by exposure to 80% oxygen from postnatal (P) days 0 to 11, followed by 7 days in room air. ROP shams were in room air from P0-18. A group of ROP rats received the AT2-RB, PD123319, by mini-osmotic pump (5 mg/kg/day) from P11-18 (angiogenesis period). Evaluation of the retinal status of the AT2 receptor indicated that this receptor, as assessed by real-time PCR, immunohistochemistry, and in vitro autoradiography, was present in the retina, was more abundant than the AT1 receptor in the neonatal retina, and was increased in the ROP model. AT2-RB reduced retinal angiogenesis. VEGF and VEGF-R2 mRNA were increased in ROP and localized to blood vessels, ganglion cells, and the inner nuclear layer, and were decreased by PD123319. Angiopoietin2 and Tie2, but not angiopoietin1 mRNA were increased with ROP, and angiopoietin2 was reduced with PD123319. This study has identified a potential retinoprotective role for AT2-RB possibly mediated via interactions with VEGF- and angiopoietin-dependent pathways.

Increased renal vascular endothelial growth factor and angiopoietins by angiotensin II infusion is mediated by both AT1 and AT2 receptors

A link between angiotensin II and cell proliferation has previously been reported. However, there remains controversy as to the role of the individual angiotensin II receptor subtypes in mediating these effects and their link to angiogenic cytokines and their receptors. Male Sprague-Dawley rats were infused with either angiotensin II or vehicle for 14 d at a dose of 58.3 ng/min. Angiotensin II-infused rats received no treatment, an AT(1) receptor antagonist valsartan (30 mg/kg per d), or an AT(2) receptor antagonist PD123319 (830 ng/min). Gene expression of vascular endothelial growth factor (VEGF) and receptor VEGF-R2, as well as Tie-2 and its ligands angiopoietin-1 (Ang-1) and angiopoietin-2 (Ang-2) were assessed by reverse transcription-PCR. Protein expression was assessed by Western blotting and immunohistochemistry. Gene and protein expression of VEGF, Ang-1, and Ang-2 were increased by angiotensin II infusion. Valsartan and PD123319 attenuated angiotensin II-associated increases in VEGF gene and protein expression. Ang-1 and Ang-2 gene but not protein expression were reduced by both treatments. These changes occurred in the context of attenuation of angiotensin II-induced glomerular cell proliferation by both valsartan and PD123319. In situ hybridization and immunohistochemical studies localized VEGF, Ang-1, and Ang-2 expression to the epithelial cells of the glomerulus, and VEGF-R2 and Tie-2 receptors to the endothelial cells of the kidney. These findings extend the increasing evidence that the AT(2) receptor, in addition to the AT(1) receptor subtype, plays an important role in mediating the proliferative actions of angiotensin II in the kidney.

Impact of high-dose peginterferon alfa-2A on virological response rates in patients with hepatitis C genotype 1: a randomized controlled trial

This study tested the hypothesis that high-dose peginterferon alfa-2a (PEG-IFNalpha-2a) for the first 12 weeks would increase early and sustained virological response (SVR) rates in patients with chronic hepatitis C genotype 1. Eight hundred ninety-six patients were randomized 1:1 to 360 microg (n = 448) or 180 microg (n = 448) PEG-IFNalpha-2a weekly plus ribavirin at 1000-1200 mg/day for 12 weeks, followed by 36 weeks of 180 microg PEG-IFNalpha-2a weekly plus ribavirin at 1000-1200 mg/day with 871 patients evaluable for the intention-to-treat analysis. Virological responses were assessed by TaqMan (limit of detection 15 IU/mL) at week 4, 8, 12, 24, 48 (end of therapy), and 24 weeks following therapy (SVR). Undetectable hepatitis C virus RNA rates were significantly higher among patients receiving high-dose induction therapy at week 4 (36% versus 26%, P < 0.005), week 8 (61% versus 50%, P < 0.005), and week 12 (74% versus 62%, P < 0.005). However, SVR was not significantly different between patients receiving high-dose (53%) and standard (50%) therapy. Significant baseline prognostic factors for SVR included age, sex, race, histological stage, and viral load. SVR was considerably higher among patients with no or minimal fibrosis (64% and 60%, respectively) compared to those with severe fibrosis/cirrhosis (28% and 24%, respectively). The frequency of serious adverse events and drug discontinuations were similar in both groups, whereas PEG-IFN dose modification, weight and appetite reduction, and grade IV neutropenia were significantly higher in the induction arm.

CONCLUSION

Induction dosing with 360 microg/week PEG-IFNalpha-2a for 12 weeks was well tolerated and enhanced early virological response but not SVR rates. The high SVR rates in patients with minimal fibrosis highlight the benefit of early treatment in patients with hepatitis C virus genotype 1.

Temporal renal expression of angiogenic growth factors and their receptors in experimental diabetes: role of the renin-angiotensin system

OBJECTIVE

It has been postulated that vascular endothelial growth factor (VEGF) plays a role in the progression of renal injury. However, the role of other angiogenic factors and their receptors, such as the angiopoietins and Tie2, and in particular their relation to renoprotective therapies, such as agents that interrupt the renin-angiotensin system, have not been studied in the context of diabetes-related renal injury.

DESIGN AND METHODS

Renal expression of VEGF, angiopoietin-1 (Ang-1), angiopoietin-2 (Ang-2) and their receptors, VEGF-R2 and Tie-2, were assessed using reverse transcription-polymerase chain reaction, immunohistochemistry and Western blotting, in control and streptozotocin diabetic rats, untreated or receiving the AT1 receptor antagonist, valsartan, or the AT2 receptor antagonist, PD123319.

RESULTS

Diabetes was associated with increased gene and protein expression of VEGF, VEGF-R2, Ang-1, Ang-2 and Tie-2. AT1 receptor antagonism attenuated gene expression of these cytokines and receptors, yet PD123319, which had no effect on blood pressure, reduced VEGF-R2 and Ang-1 gene expression and decreased VEGF, Ang-1 and Ang-2 protein levels.

CONCLUSIONS

In experimental diabetes, there is significant upregulation within the kidney of various angiogenic cytokines and their receptors. Furthermore, the effects of angiotensin II receptor blockade on these parameters is consistent with the VEGF-VEGF-R2 and angiopoietin-Tie-2 axes being modulated in the kidney by haemodynamic factors in the diabetic context.

Low virological response and high relapse rates in hepatitis C genotype 1 patients with advanced fibrosis despite adequate therapeutic dosing

BACKGROUND & AIMS

The impact of fibrosis stage on chronic hepatitis C virus (HCV) treatment response was explored in CHARIOT, a study of high dose peginterferon alfa-2a (PEG-IFNalpha-2a) induction therapy in treatment naïve genotype 1 infection.

METHODS

Eight hundred and ninety-six patients were randomised 1:1 to 360 microg (n=448) or 180 microg (n=448) PEG-IFNalpha-2a weekly with RBV 1000-1200 mg/day for 12 weeks followed by 36 weeks of 180 microg PEG-IFNalpha-2a weekly plus RBV 1000-1200 mg/day. Virological responses were assessed at week 4, 8, 12, 24, 48 (end of therapy), and 24 weeks following therapy (sustained virological response, SVR). As previously reported, there was no significant difference in SVR in the induction (53%) and standard (50%) arms, therefore the pooled study population was used for analysis of SVR and relapse.

RESULTS

A marked step-wise decline in SVR was evident by fibrosis stage: F0 (70%); F1 (60%); F2 (51%); F3 (31%); F4 (10%) (p<0.0001). Early virological responses were lower among F3/4 patients, including rapid virological response (RVR) (21% vs. 34% for F3/4 and F0-2, respectively) (p=0.0072), and the RVR positive predictive value was also lower (63% vs. 80%). Virological relapse rates were similar in early disease stages (F0, 16%; F1, 23%; F2, 26%), but increased markedly in advanced fibrosis (F3, 50%; F4, 80%) (p<0.0001). Cumulative PEG-IFNalpha-2a and ribavirin doses were similar among patients with F3/4 and F0-2 within treatment arms through week 4, 8, 12, and week 24.

CONCLUSIONS

Low virological response in hepatitis C genotype 1 patients with advanced fibrosis is not explained by inadequate cumulative PEG-IFN and ribavirin doses.

Virological response is associated with decline in hemoglobin concentration during pegylated interferon and ribavirin therapy in hepatitis C virus genotype 1

Anemia may increase the likelihood of achieving a sustained virological response (SVR) during pegylated interferon and ribavirin treatment of hepatitis C virus (HCV) infection. To determine whether hemoglobin decline is associated with SVR, we retrospectively evaluated the CHARIOT study of 871 treatment-naïve HCV genotype 1 patients. Anemia (serum hemoglobin <100 g/L) occurred in 137 (16%) patients, of whom only 14 (10%) received erythropoietin. Hemoglobin decline >30g/L from baseline occurred in 76% of patients overall, including 526 patients who did not become anemic. Virological responses were higher in anemic patients compared with those who did not develop anemia (end of treatment, 80% versus 65%, P = 0.003; SVR, 61% versus 50%, P = 0.02); these differences remained significant when patients receiving erythropoietin were excluded from analysis. SVR was also higher in patients with hemoglobin decline >30 g/L compared with patients without a similar decline. In multiple logistic regression analyses with treatment group and baseline characteristics, the odds ratio for SVR was 1.97 (95% confidence interval, 1.08-3.62) for anemia and 2.17 (95% confidence interval, 1.31-3.62) for hemoglobin decline >30 g/L. Patients who first developed a hemoglobin decline >30 g/L during weeks 5-12 and 13-48 were more likely to achieve SVR than those who first developed such changes in weeks 0-4 or who never experienced them.

CONCLUSION

Patients with HCV genotype 1 infection who develop anemia or experience a hemoglobin decline >30 g/L during weeks 5-48 of therapy achieve higher virological responses to pegylated interferon and ribavirin therapy that are unrelated to erythropoietin use.

Cardiovascular hypertrophy in one-kidney, one-clip renal hypertension is resistant to heparin

OBJECTIVE

Heparin inhibits vascular hypertrophy in angiotensin-induced hypertension, in addition to its well-known role in inhibiting injury-induced vascular smooth muscle proliferation. We tested whether hypertension and vascular hypertrophy could be reduced by heparin independently from the renin-angiotensin system.

METHODS

Rats were made hypertensive with a one-kidney, one-clip (1K1C) procedure and received heparin from osmotic minipumps (0.3 mg/h per kg i.v.) or saline vehicle for 2 weeks. Blood pressure was measured by the tail-cuff method and vessel cross-sectional area was measured by morphometry in the aorta and mesenteric arteries. Proliferation was assessed with bromodeoxyuridine labelling.

RESULTS

Blood pressure elevation and cardiovascular hypertrophy were evident in 1K1C rats. The media of mesenteric arteries was increased by 25%, and the media : lumen ratio by 35%, in hypertensive rats. DNA synthesis by smooth muscle cells in the mesenteric arteries was increased sevenfold in renal hypertension. Heparin treatment did not influence either the increase in blood pressure, the cardiovascular hypertrophy response or hypertension-mediated proliferation of arterial smooth muscle cells.

CONCLUSIONS

These data suggest that the vascular hypertrophy mechanisms operating in 1K1C renal hypertension are not inhibited by heparin and thus are different from those in angiotensin-mediated hypertension. Identifying such mechanisms in the future will be important for devising appropriate intervention strategies in angiotensin-independent forms of vascular hypertrophy.