Correction to: Repository corticotropin injection versus corticosteroids for protection against renal damage in a focal segmental glomerulosclerosis rodent model.

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Repository corticotropin injection versus corticosteroids for protection against renal damage in a focal segmental glomerulosclerosis rodent model.

BACKGROUND: Focal segmental glomerulosclerosis (FSGS) causes renal fibrosis and may lead to kidney failure. FSGS and its common complication, proteinuria, are challenging to treat. Corticosteroids are ineffective in many patients with FSGS, and alternative treatments often yield suboptimal responses. Repository corticotropin injection (RCI; Acthar® Gel), a naturally sourced complex mixture of purified adrenocorticotropic hormone analogs and other pituitary peptides, may have beneficial effects on idiopathic FSGS via melanocortin receptor activation. METHODS: Two studies in a preclinical (female Sprague-Dawley rats) puromycin aminonucleoside FSGS model assessed the effect of RCI on renal function and morphology: an 8-week comparison of a single RCI dose with methylprednisolone (N = 27), and a 12-week chronic RCI dose range study (N = 34). Primary outcomes were proteinuria and renal pathology improvements for measures of renal fibrosis, tubular damage, glomerular injury, and total kidney injury score. Impact of RCI treatment was also determined by assessing urinary biomarkers for renal injury, podocyte expression of podoplanin (a biomarker for injury), podocyte effacement by electron microscopy, and histological staining for fibrosis biomarkers. RESULTS: Compared with saline treatment, RCI 30 IU/kg significantly reduced proteinuria, with a 38% reduction in peak mean urine protein levels on day 28 in the 8-week model, and RCI 10 IU/kg, 30 IU/kg, and 60 IU/kg reduced peak mean urine protein in the 12-week model by 18, 47, and 44%, respectively. RCI also showed significant dose-dependent improvements in fibrosis, interstitial inflammation, tubular injury, and glomerular changes. Total kidney injury score (calculated from histopathological evaluations) demonstrated statistically significant improvements with RCI 30 IU/kg in the 8-week study and RCI 60 IU/kg in the 12-week study. RCI treatment improved levels of urinary biomarkers of kidney injury (KIM-1 and OPN), expression of podoplanin, and podocyte morphology. RCI also reduced levels of desmin and fibrosis-associated collagen deposition staining. Methylprednisolone did not improve renal function or pathology in this model. CONCLUSIONS: These results provide evidence supporting the improvement of FSGS with RCI, which was superior to corticosteroid treatment in this experimental model. To the authors' knowledge, this is the first evidence that a drug for the treatment of FSGS supports podocyte recovery after repeated injury.

Exogenous fluorescent tracer agents based on pegylated pyrazine dyes for real-time point-of-care measurement of glomerular filtration rate.

Novel pyrazine carboxamides bearing hydrophilic poly(ethylene glycol) (PEG) moieties were designed, synthesized, and evaluated for use as fluorescent glomerular filtration rate (GFR) tracer agents. Among these, compounds 4d and 5c that contain about 48 ethylene oxide units in the PEG chain exhibited the most favorable physicochemical and renal clearance properties. In vitro studies show that these two compounds have low plasma protein binding, a necessary condition for renal excretion. In vivo animal model results show that 4d and 5c have a higher urine recovery of the injected dose than iothalamate (a commonly considered gold standard GFR agent). Pharmacokinetic studies show that these two compounds exhibit a plasma clearance equivalent to iothalamate, but with a faster (i.e. lower) terminal half-life than iothalamate (possibly from restricted distribution into the extracellular space due to large molecular size and hydrodynamic volume). Furthermore, the plasma clearance of 4d and 5c remained unchanged upon blockage of the tubular secretion pathway with probenecid, a necessary condition for establishment of clearance via glomerular filtration exclusively. Finally, noninvasive real-time monitoring of this class of compounds was demonstrated by pharmacokinetic clearance of 5c by optical measurements in rat model, which correlates strongly with plasma concentration of the tracer. Hence, 4d and 5c are promising candidates for translation to the clinic as exogenous fluorescent tracer agents in real-time point-of-care monitoring of GFR.

Hydrophilic pyrazine dyes as exogenous fluorescent tracer agents for real-time point-of-care measurement of glomerular filtration rate.

Various hydrophilic pyrazine-bis(carboxamides) derived from 3,5-diamino-pyrazine-2,5-dicarboxylic acid bearing neutral and anionic groups were prepared and evaluated for use as fluorescent glomerular filtration rate (GFR) tracer agents. Among these, the dianionic d-serine pyrazine derivatives 2d and 2j, and the neutral dihydroxypropyl 2h, exhibited favorable physicochemical and clearance properties. In vitro studies show that 2d, 2h, and 2j have low plasma protein binding, a necessary condition for renal excretion. In vivo animal model results show that these three compounds exhibit a plasma clearance equivalent to iothalamate (a commonly considered gold standard GFR agent). In addition, these compounds have a higher urine recovery compared to iothalamate. Finally, the plasma clearance of 2d, 2h, and 2j remained unchanged upon blockage of the tubular secretion pathway with probenecid, a necessary condition for establishment of clearance via glomerular filtration only. Hence, 2d, 2h, and 2j are promising candidates for translation to the clinic as exogenous fluorescent tracer agents in real-time point-of-care monitoring of GFR.

Interferon-beta attenuates angiotensin II-accelerated atherosclerosis and vascular remodeling in apolipoprotein E deficient mice.

Atherosclerotic vascular disease is an inflammatory disease. Interferon-beta (IFN-beta) is an important immune modulator. However, the role of IFN-beta in atherosclerotic vascular disease is still not clear. The present study is designed to determine the effects of IFN-beta on atherosclerosis, abdominal aortic aneurysm (AAA) formation and proliferative vascular remodeling in apolipoprotein E (apoE) deficient mice. Six-month-old male apoE deficient mice fed a normal chow underwent ligation of the common left carotid artery, and were randomly assigned to receive either vehicle or angiotensin II (Ang II, 1.4 mg/kg daily) via a subcutaneously implanted osmotic infusion pump. The animals were further assigned to groups that were subjected to subcutaneous injection of vehicle or murine IFN-beta (10 MIU/kg, daily). Ang II increased atherosclerotic area in the non-ligated carotid artery and aortic arch, induced AAA, and exacerbated ligation-induced adventitial proliferation and neointimal hyperplasia characterized by smooth muscle cell (SMC) proliferation and macrophage infiltration in the ligated carotid artery. Co-treatment with IFN-beta, had no effects by itself, significantly attenuated Ang II-accelerated increase in the areas of neointima, adventitia, SMC and macrophage in the ligated carotid artery and suppressed Ang II-exacerbated atherosclerosis, but did not affect Ang II-induced AAA formation. These data indicate that IFN-beta can play a prominent anti-atherosclerosis, anti-inflammation, and anti-proliferation role of vasculoprotection.

A novel P2Y(12) adenosine diphosphate receptor antagonist that inhibits platelet aggregation and thrombus formation in rat and dog models.

Irreversible platelet inhibitors, such as aspirin and clopidogrel, have limited anti-thrombotic efficacy in the clinic due to their bleeding risk. We have developed an orally active reversible P2Y(12) receptor antagonist, BX 667. The aim of this study was to determine if the reversible antagonist BX 667 had a greater therapeutic index than the irreversible P2Y(12) receptor antagonist clopidogrel. Since BX 667 is rapidly converted to its active metabolite BX 048 in rats, we first injected BX 048 intravenously (iv) in a rat arterial venous (A-V) shunt model of thrombosis. BX 048 dose- and concentration-dependently attenuated thrombosis. When administered orally, BX 667 and clopidogrel had similar efficacy, but BX 667 caused less bleeding than clopidogrel. In a rat model of a platelet-rich thrombus induced by vessel injury with FeCl(2), both BX 667 and clopidogrel exhibited higher levels of thrombus inhibition after oral administration compared to their potency in the A-V shunt model. Again, BX 667 caused less bleeding than clopidogrel. In a dog cyclic flow model, iv injection of either BX 667 or clopidogrel dose-dependently reduced thrombus formation with lower bleeding for BX 667 than clopidogrel. Inhibition of thrombosis was highly correlated with inhibition of ADP-induced platelet aggregation in these animal models. In dogs pre-treated with aspirin, BX 667 maintained its wider therapeutic index, measured by inhibition of platelet aggregation over bleeding, compared to the aspirin-clopidogrel combination. These data demonstrate that the reversible P2Y(12) receptor antagonist, BX 667, has a wider therapeutic index than clopidogrel in experimental models of thrombosis.

Antiviral and myocyte protective effects of murine interferon-beta and -{alpha}2 in coxsackievirus B3-induced myocarditis and epicarditis in Balb/c mice.

The present study tested the hypothesis that murine (m)IFN-beta or mIFN-alpha(2) can eliminate cardiac viral load and protect cardiomyocytes from injury in animals infected with coxsackievirus B3 (CVB3). CVB3-inoculated male Balb/c mice exhibited signs of illness, including lethargy, progressive weight loss, and death (10% on day 3 and 100% on day 8). Cardiac viral load was high [4,277 +/- 1,009 plaque-forming units and 25 +/- 5 copies CVB3/hypoxanthine guanine phosphoribosyl transferase 1 mRNA] on day 4. The cardiac tissue exhibited severe inflammatory infiltration and myocyte damage with an average myocarditis integrated pathology score of 2.1 +/- 0.2 on day 7. Most of the mice infected with CVB3 also developed epicarditis, and 55% had intraventricular thrombi present. Treatment with mIFN-beta [2.5 to 10 million international units (MIU)/kg] dose-dependently improved the general health status in CVB3-inoculated mice, as evidenced by reduction in weight loss, prevention of death, elimination of cardiac viral load, protection of myocytes from injury, decrease in inflammatory cell infiltration, and attenuation of intraventricular thrombus formation. Treatment with 10 MIU/kg mIFN-alpha(2) resulted in a similar level of efficacy as that induced by 5 MIU/kg mIFN-beta, with the exception that mIFN-alpha(2) did not reduce cardiac CVB3 mRNA. However, mIFN-alpha(2) , but not any dose group of mIFN-beta, significantly attenuated CVB3-induced epicarditis. These data demonstrate antiviral effects for both mIFN-beta and mIFN-alpha(2), which lead to protection of the mice from CVB3-induced myocarditis. However, the potential mechanisms leading to a differential host response for the two isoforms of mIFN remain to be elucidated.

Synergistic effect of angiotensin II and nitric oxide synthase inhibitor in increasing aortic stiffness in mice.

Although they are implicated on their own as risk factors for cardiovascular disease, the potential link between nitric oxide (NO) deficiency, ANG II, and vascular stiffening has not been tested before. We evaluated the role of chronic ANG II treatment and NO deficiency, alone and in combination, on aortic stiffness in mice and tested parameters contributing to increases in active or passive components of vascular stiffness, including blood pressure, vascular smooth muscle contractility, and extracellular matrix components. Untreated (control) mice and mice treated with a NO synthase (NOS) inhibitor [N(omega)-nitro-L-arginine methyl ester (L-NAME), 0.5 g/l] were implanted with osmotic minipumps delivering ANG II (500 ng.kg(-1).min(-1)) for 28 days. Aortic stiffness was then measured in vivo by pulse wave velocity (PWV) and ex vivo by load-strain analysis to obtain values of maximal passive stiffness (MPS). Blood pressure and aortic contractility ex vivo were measured. ANG II treatment or NOS inhibition with L-NAME did not independently increase vascular stiffness; however, the combined treatments worked synergistically to increase PWV and MPS. The combined treatments of ANG II + L-NAME also significantly increased aortic wall collagen content while decreasing elastin. These novel results suggest that NO deficiency and ANG II act synergistically to increase aortic stiffness in mice predominantly via changes in aortic wall collagen/elastin ratio.

Vascular stiffness: measurements, mechanisms and implications.

Aging is the dominant process altering vascular stiffness. Risk factors for cardiovascular disease, such as smoking, hypertension and diabetes mellitus, mediate their effects by altering the structure, properties, and function of the vascular wall and endothelial components. Increased vascular stiffness exerts greater afterload stress on the heart. The ability to detect and monitor changes in the physical properties of arteries holds potential to intervene for prevention or attenuation of disease progression. Pulse wave velocity has been used as an index for vascular stiffness and as a surrogate marker for atherosclerosis in laboratory animal models and in the clinic. Mouse models have been used extensively in vascular research. We and others have developed invasive and noninvasive methods to measure pulse wave velocity in rodents, such as rats and mice. Here we review the evidence that the development of atherosclerosis contributes greatly to vascular stiffening; that endothelial nitric oxide plays an important role in modulating vascular stiffness; that angiotensin II injures the vessel and increases vascular stiffness; and that treatment with estrogen attenuates vascular inflammation and reduces vascular stiffness. In addition, we also discuss the influence of hemodynamic, metabolic, inflammatory stimuli in impairing arterial wall integrity as well as potential mechanisms modulating vascular stiffness.

Lipopolysaccharide attenuates thrombolysis in batroxobin-induced lung vasculature fibrin deposition but not in ferrous chloride-induced carotid artery thrombus in rats: role of endogenous PAI-1.

In this study, we investigated if elevation of endogenous plasminogen activator inhibitor type 1 (PAI-1) by lipopolysaccharide (LPS) can retard thrombolysis in both a rat model of lung vasculature fibrin deposition and a platelet-rich thrombus model induced by endothelial injury. By 3 h following an intravenous bolus injection of 0.5 mg/kg LPS, the plasma PAI-1 level had increased to approximately 8 ng/ml. 125I-labeled fibrinogen was injected intravenously followed by an injection of batroxobin. Batroxobin converts fibrinogen into insoluble fibrin, which was then deposited in the lungs within 5 min, followed by spontaneous fibrinolysis that completely cleared fibrin deposition in the lungs by 30 min. In rats pre-treated with LPS, spontaneous fibrinolysis was significantly retarded. In the endothelial injury model, topical application of FeCl2 on the carotid artery induced an occlusive platelet-rich thrombus, which was not sensitive to endogenous thrombolysis. Exogenous tissue-type plasminogen activator (tPA) was required to recanalize the occlusive thrombus in a dose-dependent manner. Pre-treatment with LPS did not alter the dose-response curve of exogenous tPA-induced thrombolysis. These data indicate that batroxobin-induced lung vasculature fibrin deposition in rats, unlike the FeCl2 model, is sensitive to the impact of endogenous PAI-1 on fibrinolysis.