OSTEOPROTEGERIN AS AN EARLY SIGN OF CHRONIC KIDNEY DISEASE-MINERAL AND BONE DISORDER.

Chronic kidney disease (CKD) is among the most significant health problems, with the associated cardiovascular disease and bone metabolism disorders being the leading cause of morbidity and mortality in these patients. The aim of the study was to determine markers of bone turnover in patient sera (phosphates, calcium, alkaline phosphatase, parathyroid hormone and osteoprotegerin (OPG)) in all stages of kidney failure including kidney transplant recipients. We also wanted to determine whether dialysis vintage affects recovery of bone markers one year after transplantation. There were 164 study patients, whereas 30 healthy individuals served as a control group. Serum OPG progressively increased with decline of the glomerular filtration rate. The highest OPG concentration was recorded in dialysis group. We observed a statistically significant OPG increase in stage 2 CKD. In kidney transplant group, there was positive correlation between OPG and dialysis vintage. We also found that serum OPG was lower in patients treated with dialysis for less than 4 years prior to transplantation. We confirmed that CKD-mineral and bone disorder began in stage 3 CKD with parathyroid hormone and OPG elevation, and a statistically significant OPG increase in stage 2 CKD might be an early sign of CKD-mineral and bone disorder. Dialysis vintage longer than 4 years is associated with more significant disturbances in mineral and bone metabolism.

Inhibition of miR-223 Expression Using a Sponge Strategy Decreases Restenosis in Rat Injured Carotids.

OBJECTIVE: Restenosis is a frequent complication of angioplasty. It consists of a neointimal hyperplasia resulting from progression and migration of vascular smooth muscle cells (VSMC) into the vessel lumen. microRNA miR-223 has recently been shown to be involved in cardiovascular diseases including atherosclerosis, vascular calcification and arterial thrombosis. In this study, our aim was to assess the impact of miR-223 modulation on restenosis in a rat model of carotid artery after balloon injury. METHODS: The over and down-expression of miR-223 was induced by adenoviral vectors, containing either a pre-miR-223 sequence allowing artificial miR-223 expression or a sponge sequence, trapping the native microRNA, respectively. Restenosis was quantified on stained rat carotid sections. RESULTS: In vitro, three mRNA (Myocyte Enhancer Factor 2C (MEF2C), Ras homolog gene family, member B (RhoB) and Nuclear factor 1 A-type (NFIA)) reported as miR-223 direct targets and known to be implicated in VSMC differentiation and contractility were studied by RT-qPCR. Our findings showed that down-expression of miR-223 significantly reduced neointimal hyperplasia by 44% in carotids, and was associated with a 2-3-fold overexpression of MEF2C, RhoB and NFIA in a murine monocyte macrophage cell line, RAW 264.7 cells. CONCLUSION: Down-regulating miR-223 could be a potential therapeutic approach to prevent restenosis after angioplasty.

The mir-221/222 Cluster is a Key Player in Vascular Biology via the Fine-Tuning of Endothelial Cell Physiology.

The discovery of small RNAs has shed new light on microRNA (mRNA) regulation and a range of biological processes. The recognition that miRNAs-221 and -222 are sensitive regulators in the endothelium may enable the identification of novel biomarkers and therapeutic targets. Given that endothelial dysfunction precedes the development of atherosclerosis and contributes to the development of cardiovascular damage, circulating miRNAs produced by Endothelial Cells (ECs) are putative biomarkers for a wide range of cardiovascular diseases. Furthermore, EC proliferation and migration have a critical role in the formation of new blood vessels (angiogenesis), an important component of physiological processes and tumour growth. Hence, the use of anti-angiogenic miRNAs might constitute a novel therapeutic strategy. Along with endothelial angiogenesis, several other processes involving ECs (such as neointimal lesion formation, vascular inflammation, lipoprotein metabolism and hypertension) are critical factors in atherogenesis and atherosclerosis. The fact that human blood-derived progenitor cells, endothelial progenitor cells, umbilical vein ECs and quiescent ECs express high levels of miR-221/222 suggests an important role for this miRNA cluster in endothelial (patho) physiology. The present article reviews current knowledge on miRNAs-221/222's regulation roles in endothelial function and disease in general and angiogenesis in particular.

BMP signaling in rats with TNBS-induced colitis following BMP7 therapy.

Beyond stimulating bone formation, bone morphogenetic proteins (BMPs) are important in development, inflammation, and malignancy of the gut. We have previously shown that BMP7 has a regenerative, anti-inflammatory, and antiproliferative effect on experimental inflammatory bowel disease (IBD) in rats. To further investigate the BMP signaling pathway we monitored the effect of BMP7 therapy on the BMP signaling components in the rat colon during different stages of experimentally induced colitis by 2,4,6-trinitrobenzene sulfonic acid (TNBS). The results showed a significantly decreased BMP7 expression in the acute phase, followed by a significantly increased BMP2 and decreased BMP6 expression during the chronic phase of colitis. BMP7 therapy influenced the expression of several BMPs with the most prominent effect on downregulation of BMP2 and upregulation of BMP4 in the chronic phase of colitis. Importantly, connective tissue growth factor and noggin expression were elevated in the acute stage and significantly decreased upon BMP7 therapy. BMP receptor I expression was unchanged, whereas BMP receptor II was decreased at day 2 and increased at days 14 and 30 of TNBS inflammation. However, an opposite pattern of expression following BMP7 therapy has been observed. BMP7 increased the expression of BR-Smad including Smad3 and Smad4. Inhibitory Smads were increased in colitis and significantly decreased following BMP7 therapy at later stages of the disease. We suggest that BMP signaling was altered during TNBS-induced colitis and was recovered with BMP7 administration, suggesting that IBD is a reversible process.

Hepatoregenerative role of bone morphogenetic protein-9.

Bone morphogenetic protein-9 (BMP-9) is a member of the transforming growth factor beta (TGF-ß) superfamily of cytokines, which regulate cell growth and differentiation during embryogenesis. Apart of that, the hypoglycemic potential of BMP-9 is of great interest. It has been confirmed that BMP-9, like insulin, improves glycemia in diabetic mice and regulates directional glucose metabolism in hepatocytes; therefore it is proposed to be a candidate hepatic insulin-sensitizing substance (HISS). In liver fibrosis, due to the portocaval shunt, insulin bypasses the organ and the liver undergoes atrophy. Parenteral administration of insulin reverses atrophy by stimulating mitogenic activity of the hepatocytes. Because BMP-9 has a signaling pathway similar to other BMPs and insulin, it is to be expected that BMP-9 has a certain regenerative role in the liver, supporting the above-mentioned is evidence of BMP-9 expression in Dissè's spaces and BMP-7's mitogenic activity in mucosal cells. However, further studies are needed to confirm the possible regenerative role of BMP-9.

mRNA expression of bone morphogenetic proteins and their receptors in human renal cell carcinoma.

INTRODUCTION: Bone morphogenetic proteins (BMPs) have been studied in several cancers, but only limited information is available about renal cell carcinomas (RCCs). We determined the expression of mRNA of several BMP ligands and BMP receptors (BMPRs) in healthy kidney tissue and RCCs, and data were compared to clinicopathological parameters. MATERIAL AND METHODS: Sixty-four samples of RCCs and healthy renal tissues were prospectively examined. The expression of BMP2, BMP4, BMP6, BMP7, BMPRIA, BMPRIB and BMPRII mRNA was determined using semiquantitative reverse transcriptase-polymerase chain reaction. RESULTS: The expression levels of different BMP ligands and BMPRs were considerably higher in RCCs than in normal kidney tissue. BMP ligands showed elevated expression in clear-cell RCCs, whereas all three BMPRs showed higher expression levels in non-clear-cell RCCs. In clear-cell RCCs, the expression levels of BMP2 progressively increased and expression levels of BMP6, BMP7 and BMPRIB were lost with higher tumor stage. CONCLUSIONS: All BMPs and their receptors have stronger expression levels in RCC. The expression level of BMP2 is strongly elevated in kidney cancer.

Histomorphometric analysis of subchondral bone of the femoral head in osteoarthritis and osteoporosis.

There have been reports both supporting and refuting an inverse relationship between hip fracture and hip osteoarthritis (OA). We have investigated this relationship using histomorphometric study of femoral head subchondral bone. We studied 74 subjects with hip fracture (74% females) and 24 subjects with osteoarthritis (45% females). By histomorphometric analysis of parafined sections, we analysed followed subhondral trabecular bone parameters bone volume (BV), bone volume/tissue volume (BV/TV), trabecular thickness (Tb.Th.), trabecular number (Tb.N.) and trabecular separation (Tb.S.). The subjects with osteoarthritis and subjects with hip fracture had BV/TV 31.3% and 19.6% respectively. BV/TV of osteoarthritis group was rather uniform whereas BV/TV of hip fracture group was greatly ranged and we divided it into three subgroups, 13.2%, 19.8% and 25.9% respectively. The OA group and hip fracture groups had Tb.Th. as followed 0.205 mm, 0.148 mm, 0.170 mm and 0.183 mm respectively. The OA group and hip fracture three subgroups had Tb.N. as followed 1.454/mm, 0.897/mm, 1.170/mm and 1.425/mm respectively. The OA group and hip fracture three subgroups had Tb.S. as followed 0.518 mm, 0.681 mm, 0.620 mm and 0.550 mm respectively. The results of our study support an inverse relationship between hip fracture and hip osteoarthritis.

Surgical technique in the rat model of kidney transplantation.

Today successful kidney transplantation procedures, techniques and immunosuppression protocols are a consequence of extensive research on animal models. During every transplantation surgery there are two crucial points for the success of the entire procedure: vascular (arterial end venous) and ureteral or ureterovesical anastomosis. Renal artery and vein of the donor kidney can be anastomosed end-to-side to the abdominal aorta and vena cava of the recipient (heterotopic transplantation), or end-to-end to the remains of renal artery and vain of the recipient (orthotopic transplantation) after nephrectomy. The ureter can be anastomosed also end-to-end or we can connect it directly to the urinary bladder (ureterocystoneostomy). The aim of this study was to elucidate which technique has better results according to: animal survival, reperfusion and perfusion of the transplanted kidney, elimination of the urine from the transplanted kidney and procedure costs. The study included 240 (120 donors and 120 recipients) male Wistar rats (3 months old; weight 250-300 g Our results are clearly showing that the end-to-end vascular anastomosis, and Paquins ureterovesical anastomosis have better results in transplanted rat kidneys survival and urine drainage compared to end-to-side vascular anastomosis and end-to-end ureteral anastomosis. Based on our experience we can conclude that described methods of end-to-end vascular anastomosis and Paquins ureterovesical anastomosis are less technically demanding and have a shorter learning curve. Therefore, we can recommend the use of described methods in kidney transplantation related researches.

Increased bone turnover markers after renal transplantation.

Bone remodeling is a process that occurs continuously in a seemingly inactive tissue like bone. Because of decreased vitamin D synthesis, phosphorus retention and decreased calcium blood concentration, patients with chronic renal failure (CRF) develop secondary hyperparathyroidism. Elevated PTH levels shifts balance between osteoblast and osteoclast activity in favor of osteoclast activity and, therefore, bone resorption. Bone metabolic disorder that affects patients with CRF is called renal osteodystrophy (ROD). We presume that renal transplantation reverses bone metabolism disorder and our goal was to establish whether osteoblast and osteoclast activity returns to the levels of healthy individuals.

Expression of bone morphogenetic protein-7, its receptors and Smad1/5/8 in normal human kidney and renal cell cancer.

Bone morphogenetic proteins (BMPs) are cytokines which are important for kidney homeostasis but also have role in the some renal diseases and renal cell carcinoma (RCC). In the last three decades incidence of RCC was constantly increased and the role of different molecular biomarkers in RCC is explored'. We analyzed expression of BMP-7, their receptors (BMPR-IA, BMPR-IB, BMPR-II) and proteins of their signaling pathway (pSmad1/5/8) in sixteen renal cancer samples and paired normal tissue. Tissue samples were analyzed by immunohistochemistry and Western blot. BMP-7, BMP receptors and pSmad1/5/8 were expressed in all structures of normal kidney but dominantly in the proximal tubular cells. In the cancer samples their expression was also noticed. Comparison of BMPs between different tissue showed increased expression of BMPR-IB and pSmad 1/5/8 and decreased expression of BMP-7 and BMPR-II in RCC compared to normal kidney. BMPR-IA was detected with immunohistochemistry but with Western blot attenuated signal was presented. BMP-7, BMP receptors and pSmad1/5/8 were showed in normal kidney and RCC. Detected alterations of BMP-7, BMP receptors and pSmad expression in RCC suggested their possible role in tumorigenesis of kidney cancer.