Pathomorphological sequence of nephron loss in diabetic nephropathy.

Following our previous reports on mesangial sclerosis and vascular proliferation in diabetic nephropathy (DN) (Kriz W, Löwen J, Federico G, van den Born J, Gröne E, Gröne HJ. Am J Physiol Renal Physiol 312: F1101-F1111, 2017; Löwen J, Gröne E, Gröne HJ, Kriz W. Am J Physiol Renal Physiol 317: F399-F410, 2019), we now describe the advanced stages of DN terminating in glomerular obsolescence and tubulointerstitial fibrosis based on a total of 918 biopsies. The structural aberrations emerged from two defects: 1) increased synthesis of glomerular basement membrane (GBM) components by podocytes and endothelial cells leading to an accumulation of GBM material in the mesangium and 2) a defect of glomerular vessels consisting of increased leakiness and an increased propensity to proliferate. Both defects may lead to glomerular degeneration. The progressing compaction of accumulated worn-out GBM material together with the retraction of podocytes out of the tuft and the collapse and hyalinosis of capillaries results in a shrunken tuft that fuses with Bowman's capsule (BC) to glomerular sclerosis. The most frequent pathway to glomerular decay starts with local tuft expansions that result in contacts of structurally intact podocytes to the parietal epithelium initiating the formation of tuft adhesions, which include the penetration of glomerular capillaries into BC. Exudation of plasma from such capillaries into the space between the parietal epithelium and its basement membrane causes the formation of insudative fluid accumulations within BC spreading around the glomerular circumference and, via the glomerulotubular junction, onto the tubule. Degeneration of the corresponding tubule develops secondarily to the glomerular damage, either due to cessation of filtration in cases of global sclerosis or due to encroachment of the insudative spaces. The degenerating tubules induce the proliferation of myofibroblasts resulting in interstitial fibrosis.NEW & NOTEWORTHY Based on analysis of 918 human biopsies, essential derangement in diabetic nephropathy consists of accumulation of worn-out glomerular basement membrane in the mesangium that may advance to global sclerosis. The most frequent pathway to nephron dropout starts with the penetration of glomerular capillaries into Bowman's capsule (BC), delivering an exudate into BC that spreads around the entire glomerular circumference and via the glomerulotubular junction onto the tubule, resulting in glomerular sclerosis and chronic tubulointerstitial damage.

Longitudinal airway remodeling in active and past smokers in a lung cancer screening population.

OBJECTIVES: To longitudinally investigate smoking cessation-related changes of quantitative computed tomography (QCT)-based airway metrics in a group of heavy smokers. METHODS: CT scans were acquired in a lung cancer screening population over 4 years at 12-month intervals in 284 long-term ex-smokers (ES), 405 continuously active smokers (CS), and 31 subjects who quitted smoking within 2 years after baseline CT (recent quitters, RQ). Total diameter (TD), lumen area (LA), and wall percentage (WP) of 1st-8th generation airways were computed using airway analysis software. Inter-group comparison was performed using Mann-Whitney U test or Student's t test (two groups), and ANOVA or ANOVA on ranks with Dunn's multiple comparison test (more than two groups), while Fisher's exact test or chi-squared test was used for categorical data. Multiple linear regression was used for multivariable analysis. RESULTS: At any time, TD and LA were significantly higher in ES than CS, for example, in 5th-8th generation airways at baseline with 6.24 mm vs. 5.93 mm (p < 0.001) and 15.23 mm2 vs. 13.51 mm2 (p < 0.001), respectively. RQ showed higher TD (6.15 mm vs. 5.93 mm, n.s.) and significantly higher LA (14.77 mm2 vs. 13.51 mm2, p < 0.001) than CS after 3 years, and after 4 years. In multivariate analyses, smoking status independently predicted TD, LA, and WP at baseline, at 3 years and 4 years (p < 0.01-0.001), with stronger impact than pack years. CONCLUSIONS: Bronchial dimensions depend on the smoking status. Smoking-induced airway remodeling can be partially reversible after smoking cessation even in long-term heavy smokers. Therefore, QCT-based airway metrics in clinical trials should consider the current smoking status besides pack years. KEY POINTS: • Airway lumen and diameter are decreased in active smokers compared to ex-smokers, and there is a trend towards increased airway wall thickness in active smokers. • Smoking-related airway changes improve within 2 years after smoking cessation. • Smoking status is an independent predictor of airway dimensions.

Effect of smoking cessation on quantitative computed tomography in smokers at risk in a lung cancer screening population.

OBJECTIVE: To longitudinally evaluate effects of smoking cessation on quantitative CT in a lung cancer screening cohort of heavy smokers over 4 years. METHODS: After 4 years, low-dose chest CT was available for 314 long-term ex-smokers (ES), 404 continuous smokers (CS) and 39 recent quitters (RQ) who quitted smoking within 2 years after baseline CT. CT acquired at baseline and after 3 and 4 years was subjected to well-evaluated densitometry software, computing mean lung density (MLD) and 15th percentile of the lung density histogram (15TH). RESULTS: At baseline, active smokers showed significantly higher MLD and 15TH (-822±35 and -936±25 HU, respectively) compared to ES (-831±31 and -947±22 HU, p<0.01-0.001). After 3 years, CS again had significantly higher MLD and 15TH (-801±29 and -896±23 HU) than ES (-808±27 and -906±20 HU, p<0.01-0.001) but also RQ (-813±20 and -909±15 HU, p<0.05-0.001). Quantitative CT parameters did not change significantly after 4 years. Importantly, smoking status independently predicted MLD at baseline and year 3 (p<0.001) in multivariate analysis. CONCLUSION: On quantitative CT, lung density is higher in active smokers than ex-smokers, and sustainably decreases after smoking cessation, reflecting smoking-induced inflammation. Interpretations of quantitative CT data within clinical trials should consider smoking status. KEY POINTS: • Lung density is higher in active smokers than ex-smokers. • Lung density sustainably decreases after smoking cessation. • Impact of smoking cessation on lung density is independent of potentially confounding factors. • Smoke-induced pulmonary inflammation and particle deposition influence lung density on CT.

Primary preventive potential for stroke by avoidance of major lifestyle risk factors: the European Prospective Investigation into Cancer and Nutrition-Heidelberg cohort.

BACKGROUND AND PURPOSE: Because primary prevention of stroke is a priority, our aim was to assess the primary preventive potential of major lifestyle risk factors for stroke in middle-aged women and men. METHODS: Among 23,927 persons, 551 (195 women and 356 men) had a first diagnosis of stroke during an average follow-up of 12.7 years. Using Cox proportional hazards models, we estimated the associations of adiposity, smoking, physical activity, alcohol consumption, and diet with risk of developing stroke. A competing risk model built from cause-specific proportional hazards models accounting for concurrent risk of death was used to calculate relative and absolute reductions in stroke occurrences that could have been achieved by maintaining a healthy lifestyle pattern. RESULTS: Obesity, smoking, alcohol consumption, diet, and physical inactivity were each identified as modifiable lifestyle risk factors for stroke. About 38% of stroke cases were estimated as preventable through adherence to a healthy lifestyle profile (never smoking, maintaining optimal body mass index and waist circumference, performing physical exercise, consuming a moderate quantity of alcohol, and following a healthy dietary pattern). Age-specific estimates of 5-year incidence rates for stroke in the actual cohort and in a hypothetical, comparable cohort of individuals following a healthy lifestyle would be reduced from 153 to 94 per 100,000 women and from 261 to 161 per 100,000 men for the age group 60 to 65 years. CONCLUSIONS: Our analysis confirms the strong primary prevention potential for stroke based on avoidance of excess body weight, smoking, heavy alcohol consumption, unhealthy diet, and physical inactivity.

Primary preventive potential of major lifestyle risk factors for acute myocardial infarction in men: an analysis of the EPIC-Heidelberg cohort.

The aim of this study was to assess the preventive potential of major lifestyle risk factors for acute myocardial infarction (AMI) in middle-aged men. Among 10,981 men in the Heidelberg cohort of the European Prospective Investigation into Cancer and Nutrition, aged 40.2-65.8 years when recruited, 378 developed first-ever AMI during a median follow-up period of 11.4 years. Current smoking, excess body weight, being physically inactive, but not high alcohol consumption, were identified as the major lifestyle risk factors for AMI using Cox regression analysis. A competing AMI risk model built from cause-specific Cox regression models and considering the risk of death predicted 353 AMI cases, 182 (51.6%) of which were estimated as preventable through adherence to a healthy lifestyle profile (never smoking, normal body weight, physically active, and moderate alcohol consumption). The calculated age-specific 5-year incidence rates for AMI in the actual cohort and in a hypothetical, comparable cohort with all men following the healthy lifestyle profile were 128 and 39, respectively, per 100,000 person-years for the age group 40-44, increasing to 468 and 307 per 100,000 person-years for the age group 65-69. The estimated AMI incidence rates for men with the healthy lifestyle profile are still somewhat higher than the average rates reported for documented low-incidence regions, such as parts of Japan. Our analysis confirms the strong primary preventive potential for AMI based on avoidance of smoking and excess body weight, and on regular physical activity.

Cellular senescence limits regenerative capacity and allograft survival.

Long-term graft survival after kidney transplantation remains unsatisfactory and unpredictable. Interstitial fibrosis and tubular atrophy are major contributors to late graft loss; features of tubular cell senescence, such as increased p16(INK4a) expression, associate with these tubulointerstitial changes, but it is unknown whether the relationship is causal. Here, loss of the INK4a locus in mice, which allows escape from p16(INK4a)-dependent senescence, significantly reduced interstitial fibrosis and tubular atrophy and associated with improved renal function, conservation of nephron mass, and transplant survival. Compared with wild-type controls, kidneys from INK4a(-/-) mice developed significantly less interstitial fibrosis and tubular atrophy after ischemia-reperfusion injury. Consistently, mice that received kidney transplants from INK4a/ARF(-/-) donors had significantly better survival 21 days after life-supporting kidney transplantation and developed less tubulointerstitial changes. This correlated with higher proliferative rates of tubular cells and significantly fewer senescent cells. Taken together, these data suggest a pathogenic role of renal cellular senescence in the development of interstitial fibrosis and tubular atrophy and kidney graft deterioration by preventing the recovery from injury. Inhibiting premature senescence could have therapeutic benefit in kidney transplantation but has to be balanced against the risks of suspending antitumor defenses.

Carnosine treatment largely prevents alterations of renal carnosine metabolism in diabetic mice.

Recently, we identified an allelic variant of human carnosinase 1 (CN1) that results in increased enzyme activity and is associated with susceptibility for diabetic nephropathy in humans. Investigations in diabetic (db/db) mice showed that carnosine ameliorates glucose metabolism effectively. We now investigated the renal carnosinase metabolism in db/db mice. Kidney CN1 activity increased with age and was significantly higher in diabetic mice compared to controls. Increased CN1 activity did not affect renal carnosine levels, but anserine concentrations were tenfold lower in db/db mice compared to controls (0.24±0.2 vs. 2.28±0.3 nmol/mg protein in controls; p<0.001). Homocarnosine concentrations in kidney tissue were low in both control and db/db mice (below 0.1 nmol/mg protein, p=n.s.). Carnosine treatment for 4 weeks substantially decreased renal CN1 activity in diabetic mice (0.32±0.3 in non-treated db/db vs. 0.05±0.05 µmol/mg/h in treated db/db mice; p<0.01) close to normal activities. Renal anserine concentrations increased significantly (0.24±0.2 in non-treated db/db vs. 5.7±1.2 µmol/mg/h in treated db/db mice; p<0.01), while carnosine concentrations remained unaltered (53±6.4 in non-treated vs. 61±15 nmol/mg protein in treated db/db mice; p=n.s.). Further, carnosine treatment halved proteinuria and reduced vascular permeability to one-fifth in db/db mice. In renal tissue of diabetic mice carnosinase activity is significantly increased and anserine concentrations are significantly reduced compared to controls. Carnosine treatment largely prevents the alterations of renal carnosine metabolism.

Does pregnancy or pregnancy loss increase later maternal risk of diabetes?

Evidence that childbearing is associated with future development of diabetes remains conflicting and the role of pregnancy loss in this association has not been investigated. We aimed to examine whether pregnancy and/or pregnancy loss (miscarriage, abortion, or stillbirth) are associated with maternal higher risk of diabetes later in life, using a population-based prospective cohort study (mean follow-up = 10.7 years), including 13,612 women (aged 35-65 at baseline). We found pregnancy per se did not change the risk of diabetes after considering the effect of education, smoking, alcohol consumption, physical activity, BMI, waist/hip ratio, hypertension, and hyperlipidemia (fully-adjusted OR: 1.04, 95 % CI: 0.82-1.31). Having more than four live births was associated with around two times higher risk of diabetes later in life (fully-adjusted OR: 1.77, 95 % CI: 1.12-2.80). Having more than two miscarriages was associated with about two-fold higher risk of diabetes (fully-adjusted Odd ratio (OR): 1.85, 95 % CI: 1.17-2.93). After further adjustment for parity, the higher risk of diabetes in those who had history of more than two miscarriages did not change substantially (OR: 1.82; 95 % CI: 1.15-2.88), but the association between more than four live births and diabetes disappeared when the role of pregnancy loss was considered (fully-adjusted HR: 1.06; 95 % CI: 0.54-2.08). No significant association was found between abortion, stillbirth and risk of maternal diabetes. Pregnancy per se did not increase risk of diabetes. Women who experience more than two miscarriages are at around two times higher risk of diabetes later in life. The association between high parity and diabetes is mediated by history of miscarriages and known risk factors of diabetes. The underlying reason for association between miscarriage and diabetes needs further investigation.

Exposure of pregnant rats to cigarette-smoke condensate causes glomerular abnormalities in offspring.

BACKGROUND: Higher blood pressure and albuminuria are found in offspring of mothers who smoke during pregnancy. Whether or not kidney development is affected by maternal smoking is unknown. METHODS: Sprague-Dawley rats were randomly allocated to twice-daily cigarette smoke and nicotine condensate (1 mg/kg) or vehicle at day 10 of pregnancy until delivery. RESULTS: Exposed offspring did not differ from control offspring with respect to body weight, kidney weight, albuminuria, and creatinine clearance. Both male and female offspring had higher tail-plethysmographic blood pressures and lower mean glomerular volume, podocyte, mesangial-cell, and endothelial-cell number, compared to control offspring. CONCLUSIONS: The data document that prenatal exposure to cigarette-smoke condensate containing nicotine influences normal kidney development and could predispose to higher blood pressures later in life.

Benfotiamine protects against peritoneal and kidney damage in peritoneal dialysis.

Residual renal function and the integrity of the peritoneal membrane contribute to morbidity and mortality among patients treated with peritoneal dialysis. Glucose and its degradation products likely contribute to the deterioration of the remnant kidney and damage to the peritoneum. Benfotiamine decreases glucose-induced tissue damage, suggesting the potential for benefit in peritoneal dialysis. Here, in a model of peritoneal dialysis in uremic rats, treatment with benfotiamine decreased peritoneal fibrosis, markers of inflammation, and neovascularization, resulting in improved characteristics of peritoneal transport. Furthermore, rats treated with benfotiamine exhibited lower expression of advanced glycation endproducts and their receptor in the peritoneum and the kidney, reduced glomerular and tubulointerstitial damage, and less albuminuria. Increased activity of transketolase in tissue and blood contributed to the protective effects of benfotiamine. In primary human peritoneal mesothelial cells, the addition of benfotiamine led to enhanced transketolase activity and decreased expression of advanced glycation endproducts and their receptor. Taken together, these data suggest that benfotiamine protects the peritoneal membrane and remnant kidney in a rat model of peritoneal dialysis and uremia.

Effect of paricalcitol and calcitriol on aortic wall remodeling in uninephrectomized ApoE knockout mice.

Despite an only minor reduction in the glomerular filtration rate, uninephrectomy (UNX) markedly accelerates the rate of growth of atherosclerotic plaques in ApoE-/- mice. It has been suggested that vitamin D receptor (VDR) activation exerts an antiproliferative effect on vascular smooth muscle cells, but the side effects may limit its use. To assess a potentially different spectrum of actions, we compared the effects of paricalcitol and calcitriol on remodeling and calcification of the aortic wall in sham-operated and UNX ApoE-/- mice on a diet with normal cholesterol content. Sham-operated and UNX mice were randomly allotted to treatment with solvent, calcitriol (0.03 µg/kg) or paricalcitol (0.1 µg/kg) 5 times/wk intraperitoneally for 10 wk. Semithin (0.6 µm) sections of the aorta were analyzed by 1) morphometry, 2) immunohistochemistry, and 3) Western blotting of key proteins involved in vascular calcification and growth. Compared with sham-operated animals (5.6 ± 0.24), the wall-to-lumen ratio (x100) of the aorta was significantly higher in solvent- and calcitriol-treated UNX animals (6.64 ± 0.27 and 7.17 ± 0.81, respectively, P < 0.05), but not in paricalcitol-treated UNX (6.1 5 ± 0.32). Similar differences were seen with respect to maximal plaque height. Expression of transforming growth factor (TGF)-ß1 in aortic intima/plaque was also significantly higher in UNX solvent and UNX calcitriol compared with sham-operated and UNX paricalcitol animals. Treatment with both paricalcitol and calcitriol caused significant elevation of VDR expression in the aorta. While at the dose employed paricalcitol significantly reduced TGF-ß expression in plaques, calcitriol in contrast caused significant vascular calcification and elevated expression of related proteins (BMP2, RANKL, and Runx2).

Stimulation of the calcium-sensing receptor stabilizes the podocyte cytoskeleton, improves cell survival, and reduces toxin-induced glomerulosclerosis.

Calcimimetics increase the sensitivity of the parathyroid calcium-sensing receptor to extracellular calcium for efficient control of hyperparathyroidism. Recent studies suggest that there are beneficial effects of calcimimetics beyond the control of bone and mineral homeostasis. Here, we tested whether the calcium-sensing receptor is also expressed and functionally relevant in podocytes. Analysis of microarray data using Gene Set Enrichment Analysis found that the calcimimetic R-568 influenced various pathways related to oxidative stress, cytoskeletal regulation, cell proliferation, and survival in cultured podocytes. R-568 induced a dose- and time-dependent phosphorylation of the ERK1/2-P90RSK-CREB signaling cascade, and induced pro-survival phosphorylation of BAD and Bcl-xl, thus reducing puromycin aminonucleoside (PAN)-induced podocyte apoptosis by half. Moreover, R-568 preserved the actin cytoskeleton in podocytes exposed to PAN and improved recovery from exposure to cytochalasin D, a reversible inhibitor of actin polymerization. In rats, co-administration of R-568 prevented the proteinuria caused by a single dose of PAN and attenuated the glomerulosclerosis and loss of GFR caused by repetitive puromycin treatment. Hence, calcimimetics limit podocyte damage by antiapoptotic and cytoskeleton-stabilizing effects and may constitute a new approach in the prevention and treatment of glomerular disease.

Elevated systemic TGF-beta impairs aortic vasomotor function through activation of NADPH oxidase-driven superoxide production and leads to hypertension, myocardial remodeling, and increased plaque formation in apoE(-/-) mice.

The role of circulating, systemic TGF-beta levels in endothelial function is not clear. TGF-beta(1) may cause endothelial dysfunction in apolipoprotein E-deficient (apoE(-/-)) mice via stimulation of reactive oxygen species (ROS) production by the NADPH oxidase (NOX) system and aggravate aortic and heart remodeling and hypertension. Thoracic aorta (TA) were isolated from 4-mo-old control (C57Bl/6), apoE(-/-), TGF-beta(1)-overexpressing (TGFbeta(1)), and crossbred apoE(-/-) x TGFbeta(1) mice. Endothelium-dependent relaxation was measured before and after incubation with apocynin (NOX inhibitor) or superoxide dismutase (SOD; ROS scavenger). Superoxide production within the vessel wall was determined by dihydroethidine staining under confocal microscope. In 8-mo-old mice, aortic and myocardial morphometric changes, plaque formation by en face fat staining, and blood pressure were determined. Serum TGF-beta(1) levels (ELISA) were elevated in TGFbeta(1) mice without downregulation of TGF-beta-I receptor (immunohistochemistry). In the aortic wall, superoxide production was enhanced and NO-dependent relaxation diminished in apoE(-/-) x TGFbeta(1) mice but improved significantly after apocynin or SOD. Myocardial capillary density was reduced, fibrocyte density increased, aortic wall was thicker, combined lesion area was greater, and blood pressure was higher in the apoE(-/-) x TGFbeta vs. C57Bl/6 mice. Our results demonstrate that elevated circulating TGF-beta(1) causes endothelial dysfunction through NOX activation-induced oxidative stress, accelerating atherosclerosis and hypertension in apoE(-/-) mice. These findings may provide a mechanism explaining accelerated atherosclerosis in patients with elevated plasma TGFbeta(1).

Uremia aggravates left ventricular remodeling after myocardial infarction.

BACKGROUND: Renal failure is a well-established cardiovascular risk factor. We hypothesized that uremia negatively affects post-myocardial infarction (MI) remodeling and left ventricular (LV) function and examined the pathohistological correlations. METHODS: Subtotally nephrectomized rats (SNX) and controls with MI only (MIC) were examined 1, 4 and 8 weeks after MI. MI size, ejection fraction (EF), cardiac fibrosis, vascular density and cardiomyocyte density were studied. RESULTS: The extension of MI was 0.08 +/- 0.02 in SNX versus 0.06 +/- 0.02 in MIC rats (p < 0.031). Prior to MI, EF was comparable in SNX and MIC (74 +/- 3 vs. 72 +/- 2%, n.s.). Despite a relatively small infarct size EF in SNX decreased to 58 +/- 4% 1 week after infarction and progressively worsened to 51 +/- 4% after 8 weeks. In MIC animals EF only slightly decreased 1 week after MI (70 +/- 3%) and remained unchanged at follow-up. In SNX animals LV end-diastolic diameter continuously increased following MI throughout the study period indicating accelerated remodeling. Furthermore, accelerated myocardial fibrosis was already notable 1 week after MI in SNX animals and the volume density of capillaries and cardiomyocytes was significantly lower in SNX rats. CONCLUSION: MI in experimental uremia is associated with progressive impairment of LV function, LV dilatation and accelerated myocardial fibrosis.

Expression and function of matrix Gla protein in human peritoneal mesothelial cells.

BACKGROUND: Chronic peritoneal dialysis (PD) is associated with peritoneal calcification. Studies in vascular tissue suggest that ectopic calcification is not merely a passive but a regulated process resembling bone mineralization. We investigated whether peritoneal calcification is controlled by matrix Gla protein (MGP) secreted by peritoneal mesothelial cells. METHODS: Human primary mesothelial cells (HPMC) were exposed to constituents of PD fluids and to cytokines relevant to peritoneal integrity. Messenger RNA was quantitated by real-time reverse transcription polymerase chain reaction (RT-PCR), protein abundance by Western blot and in vivo protein expression immunohistochemically. To demonstrate functional relevance, MGP was silenced in HPMC by siRNA transfection and calcium phosphate matrix deposition measured by o-cresolphthalein complexone method and von Kossa staining. RESULTS: MGP was consistently detected in the mesothelial cell layer of peritoneal tissue specimens from uraemic and non-uraemic patients, in HPMC and in culture medium. MGP mRNA and protein abundance was increased by glucose and IGF1 and decreased by TGFß1. Suppression of MGP increased matrix calcium and phosphorus deposition by 90 ± 6% and 100 ± 4% at 1 mM ambient Ca(2+) and phosphorus concentration. Deposition was not increased any further by higher medium Ca(2+)/phosphorus concentrations nor reduced by inhibition of the phosphate cotransporter Pit1. CONCLUSION: MGP is expressed by HPMC and regulated by glucose, IGF1 and TGFß1. It is a potent inhibitor of calcification in vitro and may thus play a role in the regulation of peritoneal calcium homeostasis.

Chronic low-dose isotretinoin treatment limits renal damage in subtotally nephrectomized rats.

Retinoids are anti-proliferative and anti-inflammatory compounds. We had previously shown that retinoids alleviate kidney damage in acute models of renal disease. We now examined whether retinoids are also effective in a chronic renal ablation model. Subtotally nephrectomized rats (SNx; two-third ablation) were compared to sham-operated controls (sham). SNx rats were administered either 10 mg/kg b.w. (low dose, LD) or 40 mg/kg b.w. (high dose, HD) isotretinoin or vehicle (n = 10 per group). The experiment was terminated after 16 weeks. Systolic blood pressure was significantly higher after SNx compared to sham but lower in SNx with LD isotretinoin (vs. SNx + vehicle). Compared to SNx + vehicle, SNx + LD isotretinoin had lower glomerular cell numbers, less glomerular hypertrophy and sclerosis, and less interstitial expansion. Morphological improvement in SNx + LD isotretinoin was accompanied by improvement in creatinine clearance and reduced urinary albumin excretion. In contrast, HD isotretinoin caused aggravation of renal damage with fibrinoid necroses of vessels and elevated urinary albumin excretion despite lower blood pressure. The dichotomous effects of isotretinoin are at least in part due to time- and dose-dependent alterations of transforming growth factor beta1 and collagen IV gene expression as also suggested by cell-culture studies in vascular smooth muscle cells. In addition, isotretinoin affected the systemic and the renal renin-angiotensin system (which was further analyzed in a model of angiotensin II infusion of the rat). Isotretinoin failed to cumulate at LD but cumulated at HD in SNx. We conclude that LD isotretinoin attenuates progressive renal damage, whereas HD isotretinoin cumulates and aggravates renal damage independent of blood pressure reduction.

Vascular injury biomarkers and stroke risk: A population-based study.

OBJECTIVE: Because little is known about associations between biomarkers of vascular injury and stroke risk, we evaluated associations between plasma concentrations of 6 novel biomarkers of vascular injury and stroke risk in a population-based study. METHODS: A case-cohort subset of EPIC-Heidelberg (European Prospective Investigation for Cancer and Nutrition-Heidelberg) including incident stroke cases (n = 335) and a random subcohort (n = 2,418) was selected. Concentrations of intercellular adhesion molecule 3 (ICAM3), soluble E-selectin and P-selectin, soluble thrombomodulin (sTM), thrombopoietin, and glycoprotein IIb/IIIa were measured in baseline plasma samples. Weighted Cox regression analyses were used to assess associations between biomarker levels and stroke risk. RESULTS: Median follow-up in the subcohort and among cases was 9.8 (range, 0.1-12.5) years and 6.2 (range, 0.01-12.1) years, respectively. ICAM3 levels were associated with increased risk of incident stroke after multivariable adjustment (hazard ratio, highest vs lowest quartile: 1.64 [95% confidence interval, 1.15-2.32]; p linear trend < 0.001). This association was more apparent for ischemic (1.65 [1.12-2.45]; p linear trend < 0.01) than for hemorrhagic stroke (1.29 [0.60-2.78]; p linear trend = 0.3). We further observed a borderline significant trend for a positive association between sTM and overall stroke risk (1.47 [0.99-2.19]; p linear trend = 0.05). CONCLUSIONS: In this population-based study, circulating levels of ICAM3, an adhesion molecule shed by leukocytes, were associated with increased risk of incident stroke. Further mechanistic studies are needed to elucidate the pathophysiology underlying this association. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that plasma levels of ICAM3 are associated with increased stroke risk.

Role of FTY720 on M1 and M2 macrophages, lymphocytes, and chemokines in 5/6 nephrectomized rats.

Renal injury is accompanied by the presence of infiltrating inflammatory cells in the glomerulus and tubulointerstitium. FTY720 modifies lymphocyte migration into injured tissues by lymphocyte sequestration to secondary lymphoid organs. The purpose of this study was to examine the potential of FTY720 to influence the inflammatory response in a nonimmunological model of renal failure. Sham-operated and 5/6 nephrectomized (SNX) Sprague-Dawley rats received two different doses of FTY720 or vehicle orally for 14 wk. Treatment with FTY720 reduced glomerular and tubulointerstitial damage in SNX rats but failed to stabilize creatinine clearance. The increase in gene expression of chemokine receptors CCR1, CCR2, and CCR5 in kidneys of vehicle-treated SNX rats was significantly attenuated by high-dose FTY720. Treatment with high-dose FTY720 tended to normalize RANTES and MCP-1 renal gene expression. FTY720 affected not only glomerular and tubulointerstitial lymphocytes, but M1 and M2 phenotype macrophages were also reduced. FTY720 significantly reduced key mediators of renal inflammation and fibrosis. FTY720 also decreased immunoregulation of M2 macrophages, which are beneficial for tissue remodeling and repair.

Interstitial fibrosis and microvascular disease of the heart in uremia: amelioration by a calcimimetic.

In patients with chronic renal failure, the heart undergoes remodeling, characterized by hypertrophy, fibrosis, and capillary/myocyte mismatch. In this study, we observed the effects of the calcimimetic agent R-568 on microvascular disease and interstitial fibrosis of the heart. Three-month-old male Sprague-Dawley rats were randomized to subtotal nephrectomy (SNX) or sham operation and subsequently received vehicle or R-568 under two experimental protocols, one for 1 month and the other for 3 months. Echocardiography, capillary length density, volume density of interstitial tissue, and immunohistochemistry and western blots (calcium-sensing receptor, collagen I and III, transforming growth factor (TGF)-beta, mitogen-activated protein kinases, and nitrotyrosine) were assessed. After SNX, weight and wall thickness of the left and the right ventricle were elevated. The ratio of heart to body weight and interventricular septum thickness were not changed by R-568 treatment. The left ventricle fractional shortening (by echocardiography) was lower in SNX; this was ameliorated by R-568. Reduced capillary length density and increased interstitial fibrosis in SNX were improved by R-568, which also reduced the expression of TGF-beta, and collagen I and III. The calcimimetic increased the activation of ERK-1/2, normalized p38 and JNK signaling, and prevented oxidative stress. We conclude that lowering parathyroid hormone with a calcimimetic significantly improves cardiac histology and function but not the left ventricular mass in SNX.

A calcimimetic (R-568), but not calcitriol, prevents vascular remodeling in uremia.

Renal insufficiency increases cardiovascular risk, accelerates atherogenesis, and causes vascular wall remodeling. Here we evaluated the effect of the calcimimetic R-568 and non-hypercalcemic doses of calcitriol on vascular structure. Subtotal nephrectomy was produced in Sprague-Dawley rats followed by treatment with R-568, calcitriol, or vehicle for 12 weeks. The aortic wall was significantly thicker in vehicle-treated uremic rats than in those with a sham-operation but R-568-treated uremic rats had a lower value. In contrast, calcitriol increased wall thickness in both the sham-operated and uremic groups. The calcification score, measured by von Kossa staining, and the number of proliferating cells in the intima and media were significantly higher in the calcitriol-treated uremic group. The expression of the calcium sensing receptor was higher in the intima of sham-operated and uremic rats treated with R-568 compared to animals treated with vehicle or calcitriol, while the expression of the vitamin D receptor was upregulated by both calcitriol and R-568. Our study shows that in uremic rats, calcitriol increased while R-568 attenuated media calcification and proliferation of vascular smooth muscle and endothelial cells.