Svetlana Zykova

Uric acid is a risk factor for ischemic stroke and all-cause mortality in the general population: a gender specific analysis from The Tromsø Study.

BackgroundThe role of serum uric acid as an independent predictor of cardiovascular disease and death is uncertain in the general population. Adjustments for additional cardiovascular risk factors have not been consistent. We examined the association of serum uric acid with all-cause mortality, ischemic stroke and myocardial infarction in a prospective population based study, with several traditional and non-traditional risk factors for cardiovascular disease included in the model.MethodsA population-based prospective cohort study was performed among 2696 men and 3004 women. Endpoints were all-cause mortality after 15 years, and fatal or non-fatal myocardial infarction (MI) and ischemic stroke after 12 years.Results1433 deaths, 659 MIs and 430 ischemic strokes occurred during follow-up. Fully adjusted Cox regression analyses showed that per 1 SD (87 μmol/L) increase in serum uric acid level, the risk of all-cause mortality increased in both genders (hazard ratios, HR men; 1.11, 95% CI 1.02-1.20, women; 1.16, 1.05-1.29). HRs and 95% CI for stroke were 1.31, 1.14-1.50 in men, 1.13, 0.94-1.36 in women, and 1.22 (1.09, 1.35) in the overall population. No independent associations were observed with MI.ConclusionSerum uric acid was associated with all-cause mortality in men and women, even after adjustment for blood pressure, estimated GFR, urinary albumin/creatinine ratio, drug intake and traditional cardiovascular risk factors. After the same adjustments, serum uric acid was associated with 31% increased risk of stroke in men.

Progression of Murine Lupus Nephritis Is Linked to Acquired Renal Dnase1 Deficiency and Not to Up-Regulated Apoptosis

The accumulation of apoptotic cells has been suggested as a possible mechanism of nucleosome conversion into self-antigens that may both initiate autoimmune responses and participate in immune complex deposition in lupus nephritis. In this study, we analyzed both the rate of transcription of apoptosis-related genes and the presence of activated apoptotic factors within kidneys of lupus-prone (NZBxNZW) F1 mice during disease progression. The results of this study demonstrated no activation of apoptotic pathways in kidneys of these lupus-prone mice at the time of appearance of anti-double standard DNA antibodies in serum, as well as the formation of mesangial immune deposits in glomeruli. In contrast, the transition of mesangial into membranoproliferative lupus nephritis coincided with an accumulation of activated caspase 3-positive cells in kidneys, in addition to a dramatic decrease in Dnase1 gene transcription. Highly reduced expression levels of the Dnase1 gene may be responsible for the accumulation of large chromatin-containing immune complexes in glomerular capillary membranes. Thus, the initiation of lupus nephritis is not linked to increased apoptotic activity in kidneys. The combined down-regulation of Dnase1 and the increased number of apoptotic cells, which is possibly due to their reduced clearance in affected kidneys, may together be responsible for the transformation of mild mesangial lupus nephritis into severe membranoproliferative, end-stage organ disease.

Renal Dnase1 Enzyme Activity and Protein Expression Is Selectively Shut Down in Murine and Human Membranoproliferative Lupus Nephritis

Background Deposition of chromatin-IgG complexes within glomerular membranes is a key event in the pathogenesis of lupus nephritis. We recently reported an acquired loss of renal Dnase1 expression linked to transformation from mild to severe membranoproliferative lupus nephritis in (NZBxNZW)F1 mice. As this may represent a basic mechanism in the progression of lupus nephritis, several aspects of Dnase1 expression in lupus nephritis were analyzed. Methodology/Principal Findings Total nuclease activity and Dnase1 expression and activity was evaluated using in situ and in vitro analyses of kidneys and sera from (NZBxNZW)F1 mice of different ages, and from age-matched healthy controls. Immunofluorescence staining for Dnase1 was performed on kidney biopsies from (NZBxNZW)F1 mice as well as from human SLE patients and controls. Reduced serum Dnase1 activity was observed in both mesangial and end-stage lupus nephritis. A selective reduction in renal Dnase1 activity was seen in mice with massive deposition of chromatin-containing immune complexes in glomerular capillary walls. Mice with mild mesangial nephritis showed normal renal Dnase1 activity. Similar differences were seen when comparing human kidneys with severe and mild lupus nephritis. Dnase1 was diffusely expressed within the kidney in normal and mildly affected kidneys, whereas upon progression towards end-stage renal disease, Dnase1 was down-regulated in all renal compartments. This demonstrates that the changes associated with development of severe nephritis in the murine model are also relevant to human lupus nephritis. Conclusions/Significance Reduction in renal Dnase1 expression and activity is limited to mice and SLE patients with signs of membranoproliferative nephritis, and may be a critical event in the development of severe forms of lupus nephritis. Reduced Dnase1 activity reflects loss in the expression of the protein and not inhibition of enzyme activity.

Aminated β-1,3-d-glucan improves wound healing in diabetic db/db mice

Delayed wound healing in diabetes is caused by neuropathy, vascular changes, and impaired cellular response to the injury. Macrophages are crucial in normal wound healing, and impaired functions of these cells have been shown in diabetes. β‐1,3‐d‐glucans stimulate macrophage function. This open‐label study was performed to see if aminated β‐1,3‐d‐glucan (AG) stimulates wound healing in diabetes. Four groups (1–4) of diabetic db/db mice and one nondiabetic control group, db/+(5) were studied: group 1 (n=11): topical AG; group 2 (n=10): topical AG and subcutaneous insulin; group 3 (n=14): topical placebo and subcutaneous insulin; group 4 (n=10): diabetic control (placebo); group 5 (n=12): normal control (placebo). At the end of the experiments fasting blood glucose and A1C were (mean ± SE) as follows: Group 1: 30.5 ± 1.9 mmol/L and 11.3 ± 0.6%; group 2: 12.0 ± 1.7 mmol/L and 8.0 ± 0.6%; group 3: 15.4 ± 2.4 mmol/L and 7.4 ± 0.3%; group 4: 32.6 ± 2.6 mmol/L and 12.3 ± 0.6%; group 5: 7.2 ± 0.4 mmol/L and 3.9 ± 0.04%, respectively. The closed wound area was the same in group 1 (AG alone) and group 2 (AG plus insulin) after 17 days, 57.3 ± 4.7 vs. 50.1 ± 4.9% (p=0.7).The results of these two groups were superior to group 3 (insulin treatment alone, 32.0 ± 4.3%, p<0.001) and diabetic controls (38.2 ± 5.1%, p=0.001). The macrophage‐stimulant AG improves wound healing in db/db mice.

The Relationship between Fenestrations, Sieve Plates and Rafts in Liver Sinusoidal Endothelial Cells

Fenestrations are transcellular pores in endothelial cells that facilitate transfer of substrates between blood and the extravascular compartment. In order to understand the regulation and formation of fenestrations, the relationship between membrane rafts and fenestrations was investigated in liver sinusoidal endothelial cells where fenestrations are grouped into sieve plates. Three dimensional structured illumination microscopy, scanning electron microscopy, internal reflectance fluorescence microscopy and two-photon fluorescence microscopy were used to study liver sinusoidal endothelial cells isolated from mice. There was an inverse distribution between sieve plates and membrane rafts visualized by structured illumination microscopy and the fluorescent raft stain, Bodipy FL C5 ganglioside GM1. 7-ketocholesterol and/or cytochalasin D increased both fenestrations and lipid-disordered membrane, while Triton X-100 decreased both fenestrations and lipid-disordered membrane. The effects of cytochalasin D on fenestrations were abrogated by co-administration of Triton X-100, suggesting that actin disruption increases fenestrations by its effects on membrane rafts. Vascular endothelial growth factor (VEGF) depleted lipid-ordered membrane and increased fenestrations. The results are consistent with a sieve-raft interaction, where fenestrations form in non-raft lipid-disordered regions of endothelial cells once the membrane-stabilizing effects of actin cytoskeleton and membrane rafts are diminished.

Increased glomerular matrix metalloproteinase activity in murine lupus nephritis.

Lupus nephritis is associated with thickening of the glomerular basement membrane. Here we measured expression of proteins involved in extracellular matrix turnover in kidneys of lupus-prone mice of the NZBxNZW F1 (B/W) strain before the onset of the disease until the development of proteinuria. Expression of the major isoforms of glomerular basement collagen IV (alpha3/alpha4/alpha5) was unchanged throughout disease progression. Collagen IV alpha1 and alpha2, however, were highly upregulated at the proteinuric stage while collagen IV alpha6 was increased at all time points compared to normal mice. There was increased expression of matrix metalloproteinase-2 and -9, their protein inhibitors TIMP-1 and -2 and the metalloproteinase-9 stabilizing protein lipocalin-2 in kidneys of nephritic lupus-prone mice. When proteinuria appeared we found an increased net glomerular gelatinolytic activity. These studies suggest that matrix metalloproteinases contribute to extracellular matrix expansion and proteinuria by altering matrix composition.

Reduced fragmentation of apoptotic chromatin is associated with nephritis in lupus-prone (NZB × NZW)F1 mice

OBJECTIVE Antinucleosome autoantibodies are pathogenic factors in lupus nephritis. Defects in apoptotic pathways may result in increased levels of apoptotic nucleosomes. The objectives of this study were 1) to determine whether low molecular weight oligonucleosomes are present in the kidneys of autoimmune (NZB x NZW)F(1) mice, 2) to analyze whether the presence of glomerular membrane-associated TUNEL-positive electron-dense structures reflect the existence of low molecular weight oligonucleosomes, and 3) to determine an eventual temporal relationship between glomerular electron-dense structures, oligonucleosomes, and proteinuria in these mice. METHODS DNA was isolated from mouse 111s34 hybridoma cells and from the kidneys of normal BALB/c mice in which apoptosis was induced by camptothecin and from the kidneys of (NZB x NZW)F(1) mice at ages 4 weeks, 8 weeks, 20 weeks, and > or = 26 weeks (nephritic mice). The DNA fragmentation pattern was determined with an Agilent bioanalyzer. An electron microscopy-based TUNEL assay was performed to detect apoptotic chromatin in glomerular membranes, and immunoelectron microscopy was used to determine antibody binding. Transcription levels for nucleases associated with apoptosis and necrosis were determined by real-time polymerase chain reaction. RESULTS DNA from camptothecin-treated cell lines and BALB/c mouse kidneys, but not that from untreated (NZB x NZW)F(1) mouse kidneys, demonstrated DNA cleavage consistent with apoptotic fragmentation. DNA from (NZB x NZW)F(1) mice was devoid of apoptotic fragmentation, irrespective of the age of the mice, whereas TUNEL-positive chromatin particles were detected in glomerular membranes in nephritic mice. Renal DNase I transcription was reduced in nephritic mice. Nucleosomal DNA fragmentation in response to camptothecin exposure was highly reduced in (NZB x NZW)F(1) mouse kidneys compared with that in their normal counterparts. CONCLUSION The results of this study demonstrate that TUNEL-positive chromatin particles are deposited in the glomeruli of nephritic (NZB x NZW)F(1) mice, due to reduced fragmentation and clearance of chromatin.

Glomerular matrix metalloproteinases and their regulators in the pathogenesis of lupus nephritis

Lupus nephritis is a major contributor to morbidity and mortality in systemic lupus erythematosus, but little is known about the pathogenic processes that underlie the progressive decay in renal function. A common finding in lupus nephritis is thickening of glomerular basement membranes associated with immune complex deposition. It has been speculated that alterations in the synthesis or degradation of membrane components might contribute to such changes, and thereby to initiation and progression of nephritis through facilitation of immune complex deposition. Matrix metalloproteinases (MMPs) are enzymes that are intimately involved in the turnover of major glomerular basement membrane constituents, including collagen IV and laminins. Alterations in the expression and activity of MMPs have been described in a number of renal diseases, suggesting their relevance to the pathogenesis of various glomerulopathies. The same is true for their natural inhibitors, the tissue inhibitor of metalloproteinase family. Recent data from our group have identified an increase in proteolytic activity within the glomerulus coinciding with the development of proteinuria in the mouse model of systemic lupus erythematosus. (NXB × NZW)F1 Here we review current understanding of MMP/tissue inhibitor of metalloproteinase function within the kidney, and discuss their possible involvement in the development and progression of lupus nephritis.

Macrophage stimulating agent soluble yeast β‐1,3/1,6‐glucan as a topical treatment of diabetic foot and leg ulcers: A randomized, double blind, placebo‐controlled phase II study

Dysregulated inflammatory response is believed to be an important factor in the pathogenesis of several late complications of diabetes mellitus. β‐Glucans are potent inducers of immune function. The present randomized, double blind, two‐center, placebo‐controlled study was undertaken to explore safety, tolerability and efficacy of soluble β‐1,3/1,6‐glucan (SBG) as a local treatment of diabetic foot ulcers.

Liver Aging and Pseudocapillarization in a Werner Syndrome Mouse Model

Werner syndrome is a progeric syndrome characterized by premature atherosclerosis, diabetes, cancer, and death in humans. The knockout mouse model created by deletion of the RecQ helicase domain of the mouse Wrn homologue gene (Wrn(∆hel/∆hel)) is of great interest because it develops atherosclerosis and hypertriglyceridemia, conditions associated with aging liver and sinusoidal changes. Here, we show that Wrn(∆hel/∆hel) mice exhibit increased extracellular matrix, defenestration, decreased fenestration diameter, and changes in markers of liver sinusoidal endothelial cell inflammation, consistent with age-related pseudocapilliarization. In addition, hepatocytes are larger, have increased lipofuscin deposition, more frequent nuclear morphological anomalies, decreased mitochondria number, and increased mitochondrial diameter compared to wild-type mice. The Wrn(∆hel/∆hel) mice also have altered mitochondrial function and altered nuclei. Microarray data revealed that the Wrn(∆hel/∆hel) genotype does not affect the expression of many genes within the isolated hepatocytes or liver sinusoidal endothelial cells. This study reveals that Wrn(∆hel/∆hel) mice have accelerated typical age-related liver changes including pseudocapillarization. This confirms that pseudocapillarization of the liver sinusoid is a consistent feature of various aging models. Moreover, it implies that DNA repair may be implicated in normal aging changes in the liver.