Karolina Kędzierska

Association of calpain-10 gene polymorphism and posttransplant diabetes mellitus in kidney transplant patients medicated with tacrolimus

New-onset, posttransplant diabetes mellitus (PTDM) has a high incidence after kidney transplantation in patients medicated with tacrolimus, and may adversely affect the patient and graft survival. The pathophysiology of PTDM closely mimics that of type II diabetes mellitus (T2DM). One of possible genetic factors predisposing to PTDM might be polymorphism in calpain-10 gene (CAPN10), previously associated with increased risk of T2DM in general population. Therefore, the present study was aimed at evaluation of CAPN10 gene polymorphisms in PTDM in kidney transplant patients medicated with tacrolimus. A total of 214 nondiabetic kidney transplant patients medicated with tacrolimus (56 patients with PTDM and 158 patients without PTDM were genotyped for the presence of CAPN10 gene variants (SNP-43: rs3792267:G>A, SNP-19: rs3842570 ins/del and SNP-63: rs5030952:C>T) using PCR-based assays. Frequency of SNP-63 minor allele was slightly increased in PTDM patients (P=0.056), and an association of SNP-63 heterozygosity and the risk of PTDM (odds ratios (OR)=2.45, P=0.023) was observed. An increased odds for PTDM development in patients carrying 1-1-2 haplotype (rs3792267:G-rs3842570:ins-rs5030952:T) compared to noncarriers was also noted (OR=2.35, P=0.026). Patients’ higher body mass index and SNP-63 minor T allele carrier status were identified as independent PTDM risk factors, confirmed by multivariate regression analysis. This is the first study of CAPN10 polymorphism in relation to PTDM risk. However, the application of SNP-63 (rs5030952:C>T) as a marker of PTDM should be verified by further independent studies.

Platelets arachidonic acid metabolism in patients with essential hypertension.

Arachidonic acids (AA) metabolites, eicosanoids, exert a tremendous influence on circulatory and vascular homeostasis, and in humans are generated by many organs and cell types. In this study we wanted to verify whether platelets AA metabolism play a significant role in pathogenesis of essential hypertension (EH). Participants were divided into the study (EH) and the control group. Plasma and urine concentrations of isoprostanes (8-iPF2α-III) and thromboxane B2 (TxB2) were determined using the ELISA method. The levels of 5- and 12-hydroxyeicosatetraenoic (HETE) acids, generated by platelets, were analysed using RP-HPLC. In a suspension of not stimulated and AA-stimulated platelets TxB2 level was statistically lower in the study than in the control group (p < 0.0001 and 0.001 respectively). The concentration of 12-HETE was significantly elevated in EH patients compared to the control group; however, only in the non-stimulated conditions (p < 0.05). Plasma and urine F2-isoprostanes levels were significantly higher in hypertensive individuals than in the control group (p < 0.00002 and p < 0.01 respectively). Moreover, EH patients excreted more TxB2 in urine than normotensive individuals (p < 0.05). Our results highlight the mutual connections between the platelets AA metabolism and indicate its possible role in the pathogenesis of arterial hypertension. Moreover, we hypothesize that platelets AA metabolism may exert a pro-atherosclerotic effect. Finally, we suggest the use of (5-HETE+12-HETE)/TxB2 parameter in further studies.

Activity of CuZn-superoxide dismutase, catalase and glutathione peroxidase in erythrocytes in kidney allografts during reperfusion in patients with and without delayed graft function.

Abstract:  Background:  Generation of reactive oxygen species (ROS) is the main mechanism involved in the ischemic/reperfusion damage of the transplanted organ. Oxygen burst is a trigger for complex biochemical events leading to generation of oxygenated lipids and changes in microcirculation. Many markers have been researched to prove the presence of ROS in the transplanted tissue. Some of them, like superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) are considered to play a major role in graft protection against oxygen stress during reperfusion.

Association of transcription factor 7-like 2 (TCF7L2) gene polymorphism with posttransplant diabetes mellitus in kidney transplant patients medicated with tacrolimus

New onset posttransplant diabetes mellitus (PTDM) has a high incidence after kidney transplantation in patients medicated with tacrolimus. PTDM can adversely affect patient and graft survival. The pathophysiology of PTDM closely mimics type 2 diabetes mellitus (T2DM). One of the possible genetic factors predisposing individuals to PTDM might be a polymorphism in the transcription factor 7-like 2 gene (TCF7L2). This polymorphism has previously been associated with increased risk of T2DM in the general population. Therefore, the present study aimed to evaluate TCF7L2 polymorphisms in PTDM in kidney transplant patients medicated with tacrolimus. Non-diabetic kidney transplant patients medicated with tacrolimus (n = 234) were genotyped for the presence of TCF7L2 gene variants (rs12255372 and rs7903146) using TaqMan probes. Of the 234 patients, 66 patients had developed PTDM and 168 had not. Frequencies of the studied single nucleotide polymorphisms (SNPs) did not differ significantly between the study groups. Moreover, haplotype analyses failed to detect any associations between TCF7L2 haplotypes and PTDM. However, in late-onset PTDM (developed later that 2 weeks from transplantation), frequencies of the rs7903146 TT genotype and T minor allele were significantly increased compared to non-PTDM controls (17.9% vs. 5.9%, p = 0.017, OR: 4.13, 95% CI: 1.19-14.33 for TT genotype, 39.3% vs. 25.9%, p = 0.038 for T allele). If the application of TCF7L2 rs7903146 SNPs as a marker for PTDM is confirmed by further independent studies, replacing tacrolimus with other immunosuppressants could be warranted in patients at high risk of PTDM, as diagnosed by TCF7L2 genotyping.

Oxidative Stress and Renal Interstitial Fibrosis in Patients After Renal Transplantation: Current State of Knowledge

Long-term outcomes in renal transplantation has represented a major challenge for transplantologists and nephrologists for many years. The use of a new generation of immunosuppressive drugs has contributed to reducing the incidence of acute rejection episodes, but chronic allograft nephropathy is the cause of renal allograft loss in ∼50% of recipients. Organ fibrosis is the main histopathologic finding in those cases. Many researchers have focused on mechanisms leading to fibrosis. It is thought that an explanation of the pathologic mechanism of this phenomenon may improve long-term effects of therapy for kidney transplant recipients.

Does Glucose Present in the Dialysate Limit Oxidative Stress in Patients Undergoing Regular Hemodialysis

Background: Decreased glucose concentration in the blood causes the inhibition of the hexose monophosphate (HMP) cycle in the erythrocyte. NADPH, which is the source of the reductive equivalents necessary for the reproduction of glutathione (GSH), is not regenerated. The presence of glucose in dialysate should provide the stability of its concentration in the blood of patients undergoing hemodialysis (HD). The aim of the study was to assess the influence of glucose in the dialysate on the intensity of oxidative stress in patients undergoing regular HD. Methods: The study comprised 43 patients hemodialyzed with dialysate containing (HD-g(+)) or not containing glucose (HD-g(–)). The concentrations of the products of reaction with thiobarbituric acid-reactive substance (TBARS) and GSH as well as the activity of erythrocyte superoxide dismutase were determined. Glucose concentrations in the blood before and immediately after dialysis were also measured. Results: After flow-through dialysis the glucose concentration in the blood decreases both when dialysate does not contain glucose (4.8 vs. 1.6 mmol/l) and when dialysate contains glucose (6.6 vs. 5.8 mmol/l). HD caused changes in the TBARS concentration: in the HD-g(+) group the concentration decreased after HD, whereas in the HD-g(–) group it increased. In both groups of patients studied the GSH concentration changed after HD; in the HD-g(–) group it decreased and in the HD-g(+) group it increased. The results obtained in the groups of patients examined were confirmed by in vitro studies. Conclusions: The presence of glucose in the dialysate guarantees the normal activity of the HMP cycle, which provides the production of reductive equivalents for the regeneration of reduced GSH – free radicals scavenger – and therefore the limitation of oxidative stress.

Influence of angiotensin I‐converting enzyme polymorphism on development of post‐transplant erythrocytosis in renal graft recipients

Abstract:  Background:  Post‐transplant erythrocytosis (PTE) is estimated at 5–20%. Angiotensin II generated by angiotensin I‐converting enzyme (ACE) stimulates erythropoiesis. The highest activity of ACE is observed in DD genotype. The question arises if ACE gene polymorphism influences PTE.

Influence of Glucose in Dialyzing Fluid on Purine Concentrations in Hemodialyzed Patients with Chronic Renal Failure

Background: In chronic renal failure the accumulation of some purine nucleotides (in erythrocytes) develops both in patients undergoing conservative treatment and in hemodialyzed patients. The aim of the study was: (1) To find if hemodialysis (HD) sessions using dialyzing fluid containing glucose leads to an increase in ATP concentration and changes in the concentration of other nucleotides, nucleosides and oxypurines in erythrocytes. The potential consequence of such purine concentration changes is the increase of 2,3-DPG concentration and an improved transportation of oxygen in erythrocytes which are more resistant to hemolysis. (2) To compare blood concentrations of purine nucleotides, nucleosides and oxypurines in patients undergoing chronic HD with dialyzing fluid containing or lacking glucose. Significant differences could suggest the long-term influence of glucose in dialyzing fluid on erythrocyte energetic state. Methods: Whole blood nucleotide concentrations were evaluated with the use of a high-performance liquid chromatography technique. Results: Before the HD session the patients in the ‘plus glucose’ group had significantly higher concentrations of ATP, ADP, AMP, TAN, NAD, NADP, GTP + GDP, GMP, Urd and HYP than patients in the ‘no glucose’ group. After the HD the patients in the ‘plus glucose’ group had significantly higher concentrations of ADP, AMP, TAN, NAD, NADP, Urd and HYP than in the ‘no glucose’ group. Both before and after the HD session, the uric acid concentrations and AEC were significantly lower in the ‘plus glucose’ group than in the ‘no glucose’ group. A significant decrease in the whole blood hypoxanthine (p < 0.05) and uric acid (p < 0.001) concentrations after HD was found in the ‘no glucose’ group while a significant increase in ADP concentration (p < 0.05) was detected in the patients’ erythrocytes in the ‘plus glucose’ group. In this group a significant decrease of GTP + GDP and GMP (p < 0.05), uric acid concentration (p < 0.001) and adenylate energy charge (p < 0.05) were observed after the dialysis. However, no significant differences in nucleotide concentrations before and after the HD were found in the ‘no glucose’ group. Conclusion: The presence of glucose in the dialyzing fluid causes a significant modification of the energetic state of cells which is reflected by the purines’ and their metabolites’ concentrations in the erythrocytes. Higher ATP concentrations in patients with renal failure who have been dialyzed with the fluid containing glucose can be considered as an organism adaptation to a decreased amount of RBC and hemoglobin concentration.

The effect of immunosuppressive therapy on renal cell apoptosis in native rat kidneys

AIM To analyse the impact of the most commonly used immunosuppressive drugs on the occurrence of apoptosis in the native kidneys of Wistar rats. METHOD The study involved 36 rats. the animals being grouped according to the immunosuppressive regimen used (tacrolimus, mycophenolate mofetil, cyclosporine A, rapamycin and prednisone). The rats in all study groups were treated with a 3-drug protocol for 6 months. The medication dose was adjusted based on available literature data. No drugs were administered to the control group. The rats were then killed. Autopsies of all animals were performed and the kidneys were isolated for histopathology (HE + PAS). To assess cell apoptosis the TUNEL reaction was performed. Blood trough levels of immunosuppressive drugs as well as the parameters of peripheral blood were determined. RESULTS 1. In rats treated with cyclosporine A distal nephron tubules were characterised by more pronounced apoptosis. 2. In tacrolimus-treated rats a lower intensity of apoptosis was found in the distal tubules. 3. In rapamycin-treated rats the apoptosis was inhibited both in the distal and proximal nephron tubules. 4. In MMF treated rats intense apoptosis was observed in the proximal nephron tubules. 5. There were no significant changes in renal histopathology (HE + PAS). CONCLUSIONS The apoptosis in nephron tubules caused by immunosuppressive therapy is not accompanied by any histopathological changes (eg fibrosis, inflammation, tubular atrophy, vacuolation of the tubular cells) in light microscopy.

Effects of immunosuppressive treatment on protein expression in rat kidney

The structural proteins of renal tubular epithelial cells may become a target for the toxic metabolites of immunosuppressants. These metabolites can modify the properties of the proteins, thereby affecting cell function, which is a possible explanation for the mechanism of immunosuppressive agents’ toxicity. In our study, we evaluated the effect of two immunosuppressive strategies on protein expression in the kidneys of Wistar rats. Fragments of the rat kidneys were homogenized after cooling in liquid nitrogen and then dissolved in lysis buffer. The protein concentration in the samples was determined using a protein assay kit, and the proteins were separated by two-dimensional electrophoresis. The obtained gels were then stained with Coomassie Brilliant Blue, and their images were analyzed to evaluate differences in protein expression. Identification of selected proteins was then performed using mass spectrometry. We found that the immunosuppressive drugs used in popular regimens induce a series of changes in protein expression in target organs. The expression of proteins involved in drug, glucose, amino acid, and lipid metabolism was pronounced. However, to a lesser extent, we also observed changes in nuclear, structural, and transport proteins’ synthesis. Very slight differences were observed between the group receiving cyclosporine, mycophenolate mofetil, and glucocorticoids (CMG) and the control group. In contrast, compared to the control group, animals receiving tacrolimus, mycophenolate mofetil, and glucocorticoids (TMG) exhibited higher expression of proteins responsible for renal drug metabolism and lower expression levels of cytoplasmic actin and the major urinary protein. In the TMG group, we observed higher expression of proteins responsible for drug metabolism and a decrease in the expression of respiratory chain enzymes (thioredoxin-2) and markers of distal renal tubular damage (heart fatty acid-binding protein) compared to expression in the CMG group. The consequences of the reported changes in protein expression require further study.