D. Drulis-Fajdasz

Long term potentiation affects intracellular metalloproteinases activity in the mossy fiber — CA3 pathway

Matrix Metalloproteinases (MMPs) are a family of endopeptidases known to process extracellular proteins. In the last decade, studies carried out mainly on the Schaffer collateral-CA1 hippocampal projection have provided solid evidence that MMPs regulate synaptic plasticity and learning. Recently, our group has shown that MMP blockade disrupts LTP maintenance also in the mossy fiber-CA3 (mf-CA3) projection (Wojtowicz and Mozrzymas, 2010), where LTP mechanisms are profoundly different (NMDAR-independent and presynaptic expression site). However, how plasticity of this pathway correlates with activity and expression of MMPs remains unknown. Interestingly, several potential MMP substrates (especially of gelatinases) are localized intracellularly but little is known about MMP activity in this compartment. In the present study we have asked whether LTP is associated with the expression and activity of gelatinases in apparent intra- and extracellular compartments along mf-CA3 projection. In situ zymography showed that LTP induction was associated with increased gelatinases activity in the cytoplasm of the hilar and CA3 neurons. Using gelatin zymography, immunohistochemistry and immunofluorescent staining we found that this effect was due to de novo synthesis and activation of MMP-9 which, 2-3h after LTP induction was particularly evident in the cytoplasm. In contrast, MMP-2 was localized preferentially in the nuclei and was not affected by LTP induction. In conclusion, we demonstrate that LTP induction in the mf-CA3 pathway correlates with increased expression and activity of MMP-9 and provide the first evidence that this increase is particularly evident in the neuronal cytoplasm and nucleus.

Kidney ischemic injury genes expressed after donor brain death are predictive for the outcome of kidney transplantation.

The results of deceased donor kidney transplantation largely depend on the extent of organ injury induced by brain death and the transplantation procedure. In this study, we analyzed the preprocurement intragraft expression of 29 genes involved in apoptosis, tissue injury, immune cell migration, and activation. We also assessed their influence on allograft function. Before flushing with cold solution we obtained 50 kidney core biopsies of deceased donor kidneys immediately after organ retrieval. The control group included 18 biopsies obtained from living donors. Gene expression was analyzed with low-density arrays (Taqman). LCN2/lipocalin-2 is considered a biomarker of kidney epithelial ischemic injury with a renoprotective function. HAVCR1/KIM-1 is associated with acute tubular injury. Comparison of deceased donor kidneys to control organs revealed a significantly higher expression of LCN2 (8.0-fold P=.0006) and HAVCR1 (4.7-fold, P<.0001). Their expressions positively correlated with serum creatinine concentrations after 6 months after transplantation: LCN2 (r=.65, P<.0001), HAVCR1 (r=.44, P=.006). Kidneys displaying delayed graft function and/or an acute rejection episode in the first 6 months after showed higher LCN2 expression compared to event-free ones (1.7-fold, P=.027). A significantly higher increase in expression of TLR2 (5.2-fold), Interleukin (IL) 18 (4.6-fold), HMGB1 (4.1-fold), GUSB (2.4-fold), CASP3 (2.0-fold) FAS (1.8-fold), and TP53 (1.6-fold) was observed among deceased donor kidneys compared with the control group. Their expression levels were not related to clinical outcomes: however, they showed significant correlations with one another (r>.6, P<.0001). We also observed a slightly reduced expression of IL10 (0.6-fold, P=.004). Our data suggested that increased LCN2 and HAVCR1 expression observed in the kidneys after donor brain death were hallmarks of the organ injury process. LCN2 expression level in retrieved kidneys can predict kidney transplantation outcomes.

Duration of Brain Death and Cold Ischemia Time, But Not Warm Ischemia Time, Increases Expression of Genes Associated With Apoptosis in Transplanted Kidneys From Deceased Donors

Apoptosis is one of the most important mechanisms leading to kidney graft injury during transplantation. The aim of this study was to assess the expression of genes involved in apoptosis in transplanted kidneys derived from deceased donors (DD) at various stages of the transplant procedure, seventy eight transplanted kidneys procured from 43 DD were included in this study. As a baseline control for gene expressions we used six kidney allografts obtained from living donors (LD). Three core biopsies were performed: biopsy 1--5 minutes before organ perfusion in the donor; biopsy 2--at the end of cold ischemia before kidney implantation; and biopsy 3--30 minutes after reperfusion. Tumor protein p53 (TP53), caspase-3 (CASP3), B-cell lymphoma 2 protein (Bcl2), and heme oxygenase 1 (HO-1) gene expression levels were determined using custom-designed low-density arrays (TaqMan assay). Comparison of gene expression between DD and LD kidneys revealed greater expression of all genes in kidneys from DD in all biopsies; however, only CASP3 expression in biopsy 1 and TP53 expression in biopsy 3 were statistically significant. Prolongation duration of brain death beyond 10 hours in DD resulted in a significantly decreased CASP3 expression in biopsy 1. When the cold ischemia time (CIT) was longer than 24 hours, the expressions of Bcl2, TP53, and CASP3 were significantly higher compared to kidneys with ClT<24 hours. There was no correlation between warm ischemia time and gene expression in biopsy 3. CASP3 and TP53 expression only in biopsy 1 were significantly higher among kidney allografts with delayed (DGF) compared with immediate graft function. In conclusion expression of genes involved in apoptosis was more pronounced in kidney allografts from deceased donors. A prolonged donor brain-death period beyond 10 hours resulted in decreased CASP3 expression. CIT longer than 24 hours was associated with increased expressions of Bcl2, TP53, and CASP3. CASP3 and TP53 expressions were significantly higher among kidneys allografts displaying DGF.

Impact of Donor-Dependent Genetic Factors on Long-Term Renal Graft Function

Our aim was to study the association of donor genetic features with long-term graft function as well as the impact of donor age, gender compatibility, cold ischemia time (CIT), and delayed graft function (DGF). We observed the outcomes of 125 kidney recipients for a minimum of 12 months (mean, 30.9 +/- 13.0 months). Grafts were obtained from 89 donors who underwent profiling for AHSG 1/2, MMP9 -1562C/T, IL6 -174G/C, IL1beta 3954C/T, MTHFR 677C/T, MTHFR 1298A/C, NOS3 -786C/T, and PAI1 4G/5G single-nucleotide polymorphisms (SNPs) using sequence-specific probe (SSP) polymerase chain reaction (PCR) and MPO -463G/A and CRP -390C/T/A with restriction fragment length polymorphism (RFLP) analysis. NOS3 IVa/b VNTR polymorphism was genotyped by gel electrophoresis of the respective PCR-generated DNA fragment. The presence of the aa eNOS genotype was connected with worse graft function. The aa genotype was also linked to acute rejection episodes. The lowest values of glomerular filtration rate (GFR) were displayed by recipients of grafts from donors with homozygotic PAI1 gene 5G polymorphism, linking paradoxically with lower PAI-1 synthesis suggesting that the intensity of proteolysis led to increased alloantigen specificity stimulating alloresponses. Graft function depended significantly on donor age with an influence of gender matching. GFR showed a significant dependence on DGF. Genetic features of the donor influenced long-term graft function. Variant eNOS gene polymorphism, which produced decreased eNOS activity, was linked to worse remote graft function. A similar negative impact was observed in the case of donor PAI1 polymorphism, with the functional consequence of lower gene product synthesis.

Recipient Genetic Determinants of Inflammatory Process and Nonstandard Atherosclerosis Risk Factors Affect Kidney Graft Function Early Posttransplantation

We analyzed the connections between recipient genetic features and 12-month graft function. The gene polymorphisms of myeloperoxidase (MPO), interleukin (IL)-1beta, IL-6, C-reactive protein (CRP), fetuin A, and homocysteine and their gene product concentrations were correlated with 12-month kidney transplant function. The 125 kidney recipients had at least 12 months of follow-up (average, 30.9 +/- 13.0 months). IL6-174G/C, IL1beta 3954C/T, MTHFR 677C/T, MTHFR 1298A/C, AHSG 1/2 SNPs were determined using SSP-polymerase chain reaction (PCR) and MPO-463G/A and CRP- 390C/T/A with RLFP analysis. Enzyme-linked immunosorbent assay (ELISA) was applied to estimate MPO, fetuin A, IL-6, and IL-1beta; FPIA was applied for L-homocysteine concentrations. The highest CRP values were linked to the presence of the TT genotype. We observed a positive correlation of CRP concentrations and GFR. Lower fetuin A concentrations were linked to the 256Ser allele, and higher levels to better graft function. Worse graft function was inversely associated with serum homocysteine concentrations. Two polymorphisms (CRP and fetuin A) showed functional consequences in recipients. None of the examined genetic determinations influenced long-term graft function. Higher values, although still within the normal range of CRP concentrations on the day of transplantation and 3 months thereafter, were related to greater values of eGFR at 12 months, suggesting that the higher intensity of the inflammatory reaction may be a manifestation of more effective healing of an ischemia reperfusion injury. Both homocysteine and fetuin A showed long-term prognostic importance.

The influence of warm ischemia elimination on kidney injury during transplantation - Clinical and molecular study

Kidney surface cooling was used during implantation to assess the effect of warm ischemia elimination on allograft function, histological changes and immune-related gene expression. 23 recipients were randomly assigned to a group operated on with kidney surface cooling during implantation (ice bag technique, IBT group), and the other 23 recipients receiving the contralateral kidney from the same donor were operated on with a standard technique. Three consecutive kidney core biopsies were obtained during the transplantation procedure: after organ recovery, after cold ischemia and after reperfusion. Gene expression levels were determined using low-density arrays (Format 32, TaqMan). The IBT group showed a significantly lower rate of detrimental events (delayed graft function and/or acute rejection, p = 0.015) as well as higher glomerular filtration rate on day 14 (p = 0.026). A greater decrease of MMP9 and LCN2 gene expression was seen in the IBT group during total ischemia (p = 0.003 and p = 0.018). Elimination of second warm ischemia reduced the number of detrimental events after kidney transplantation, and thus had influence on the short-term but not long-term allograft function. Surface cooling of the kidney during vascular anastomosis may reduce some detrimental effects of immune activation resulting from both brain death and ischemia-reperfusion injury.