Tanja Ćelić

Mn porphyrin-based SOD mimic, MnTnHex-2-PyP5+, and non-SOD mimic, MnTBAP3−, suppressed rat spinal cord ischemia/reperfusion injury via NF-κB pathways

Abstract Herein we have demonstrated that both superoxide dismutase (SOD) mimic, cationic Mn(III) meso-tetrakis(N-n-hexylpyridinium-2-yl)porphyrin (MnTnHex-2-PyP5+), and non-SOD mimic, anionic Mn(III) meso-tetrakis(4-carboxylatophenyl)porphyrin (MnTBAP3−), protect against oxidative stress caused by spinal cord ischemia/reperfusion via suppression of nuclear factor kappa B (NF-κB) pro-inflammatory pathways. Earlier reports showed that Mn(III) N-alkylpyridylporphyrins were able to prevent the DNA binding of NF-κB in an aqueous system, whereas MnTBAP3− was not. Here, for the first time, in a complex in vivo system—animal model of spinal cord injury—a similar impact of MnTBAP3−, at a dose identical to that of MnTnHex-2-PyP5+, was demonstrated in NF-κB downregulation. Rats were treated subcutaneously at 1.5 mg/kg starting at 30 min before ischemia/reperfusion, and then every 12 h afterward for either 48 h or 7 days. The anti-inflammatory effects of both Mn porphyrins (MnPs) were demonstrated in the spinal cord tissue at both 48 h and 7 days. The downregulation of NF-κB, a major pro-inflammatory signaling protein regulating astrocyte activation, was detected and found to correlate well with the suppression of astrogliosis (as glial fibrillary acidic protein) by both MnPs. The markers of oxidative stress, lipid peroxidation and protein carbonyl formation, were significantly reduced by MnPs. The favorable impact of both MnPs on motor neurons (Tarlov score and inclined plane test) was assessed. No major changes in glutathione peroxidase- and SOD-like activities were demonstrated, which implies that none of the MnPs acted as SOD mimic. Increasing amount of data on the reactivity of MnTBAP3− with reactive nitrogen species (RNS) (.NO/HNO/ONOO−) suggests that RNS/MnTBAP3−-driven modification of NF-κB protein cysteines may be involved in its therapeutic effects. This differs from the therapeutic efficacy of MnTnHex-2-PyP5+ which presumably occurs via reactive oxygen species and relates to NF-κB thiol oxidation; the role of RNS cannot be excluded.

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

Summary Bone morphogenetic protein-9 (BMP-9) is a member of the transforming growth factor beta (TGF-β) 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.

Bone Morphogenetic Protein-7 Reduces Cold Ischemic Injury in Rat Kidney

BACKGROUND Deceased donor kidneys have a high incidence of delayed graft function attributable to ischemia-reperfusion injury. Although preservation solution and cold storage reduce cold ischemic injury, the depletion of cellular energy and oxidative signalling leads to cellular damage. Because bone morphogenetic protein-7 has renoprotective effect, we have hypothesized that recombinant human bone morphogenetic protein-7 (rh BMP-7) will better preserve kidney tissue exposed to prolonged cold ischemia in comparison with University of Wisconsin (UW) solution. We evaluated how the duration of cold ischemia influences the cold ischemic injury. METHODS Levels of lipid peroxidation, protein carbonyl content, as well as superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities were determined in the kidneys by spectrophotometry after 6, 12, and 24 hours of cold ischemia. RESULTS Time-dependent increases in the levels of lipid peroxidation and protein carbonyl content at all time points were significantly lower in rhBMP-7-perfused kidneys versus the UW-treated group. SOD activity after 6 hours, as well as GSH-Px activity after 24 hours of cold ischemia was significantly higher in the kidney tissue perfused by rhBMP-7 than in UW group. CONCLUSION rhBMP-7 significantly decreases cellular damage in rat kidney versus UW preservation solution and this is attributed to lowering of cold ischemia injury and maintaining prolonged tissue antioxidant activity.

Serum Bone Markers and Coronary Artery Calcification in End Stage Renal Failure Patients and Kidney Transplant Recipients

Background: Variety of growth factors and cytokines are involved in the process of bone turnover. Evidences are showing that alterations in OPG/RANK/RANKL system form the basis of many metabolic diseases. So, we evaluated the relationship between OPG and RANKL levels, to establish a possible relationship with other bone markers and coronary artery calcification. Methods: Patients with chronic kidney disease and patients during the first year after transplantation had coronary artery scan and their blood was analyzed for serum bone markers. The following serum markers were measured: OPG, RANKL, BAP, TRAP5b and iPTH. Results: All measured bone markers values increased with the disease progression and return to normal values during the first year after transplantation. Serum values of OPG, BAP, TRAP5b and iPTH are influenced by gender, age and dialysis duration. There is a significant negative correlation between PTH and OPG, and positive between PTH, BAP and TRAP5b values. No correlation between OPG and sRANKL, or OPG/sRANKL levels with other tested markers was found. In multivariate analysis of CACS revealed that OPG is significantly correlated with calcification in entire study population. Conclusions: This study shows that increased bone turnover markers are present in chronic kidney disease but mainly depending on gender, age and dialysis duration. The effects of those factors are overridden by glucocorticoids effect in transplanted patients. The correlation of OPG with arterial calcification presents it as a possible calcification marker. This is the first study on bone metabolism that covered Chronic Kidney Disease (CKD) patients, both predialysed and hemodialysed, as well as kidney transplant recipients. Results of our study demonstrate that serum levels of all investigated bone markers as well as calcification of coronary arteries are increased during CKD, with highest measured values in HD population.