Új pathomechanizmusok és kezelési lehetőségek vizsgálata a vese ischémia/reperfúziós károsodásában és krónikus allograft nephropathiában = Investigation of new pathomechanisms and treatment possibilities of renal ischemia/reperfusion injury and chronic allograft nephropathy

Eredményeink az erythropoietin (EPO) védő szerepét igazolták egyoldali vese ischemia/reperfúziós (I/R) károsodásban. Ez a védő szerep elsősorban hímekben igazolható. Hátterében az EPO HSP72-mediálta hatása állhat, amellyel a Na+/K+ ATP-áz funkciójának megtartását segíti elő. Vizsgálataink során az EPO sejt-protektív hatásának hátterében egy új szignál molekulát is sikerült azonosítanunk, a szérum és glükokortikoid aktiválta kináz-1-t (SGK1). Ezek az eredmények az EPO által kifejtett sejtprotekció hátterében álló új pathomechanizmusokat írtak le. Eredményeink alapján az EPO, illetve a leírt útvonalakra ható egyéb szerek további vizsgálata és klinikai hasznosítása jöhet szóba. Másik vizsgálatunk során az I/R-s károsodás kivédésében szerepet játszó mechanizmusok során megfigyelhető nemi különbségeket írtuk le. Igazoltuk, hogy hímekben elsősorban a HIF 1α, míg nőstényekben a HSF útvonal tűnik fontosabbnak. Végül igazoltuk. hogy az SGK1 anti-apoptotikus és sejtvédő funkciójában is nemi különbségek mutathatók ki I/R-t követően. Ezekkel az eredményeinkkel magyarázhatóak az irodalomban korábban leírt és egymásnak ellentmondó közlések, amelyek a tesztoszteron SGK1 reguláló hatását mutatták be. | Our results suggest that EPO protects against severe, unilateral renal I/R injury, especially in male rats. This beneficial effect might be partly the result of EPO’s HSP72-mediated impact on Na+/K+ATPase-α1. Moreover, our data report a new signaling molecule to be involved in EPO cytoprotective actions, since we identified for the first time an important role of SGK1 in the renoprotective effect of EPO. These observations provide insights into a novel signaling mechanism by which EPO partly exerts its potent tissue protective actions. Given our results along with previous reports, the clinical use of EPO possibly leading to reduced cellular damage due to ischemic events should be considered. Our study has revealed a gender-dependent protective mechanism during renal I/R injury. In males mostly the HIF 1α, while in females the HSF is the dominant transcriptional pathway. The EPO treatment results in disappearance of the characteristic signal pathway activation in both genders. The explanation for that could be either a direct negative feedback effect on the transcription factors or an indirect renal protective effect of EPO by which these transcriptional factors do not need to be activated. We could also demonstrate that the anti-apoptotic SGK1 shows a gender-specific expression pattern after renal I/R with higher levels in male rats. These results confirm previous contradictory reports showing that SGK1 might be up-regulated and activated by testosterone

Analysis of Linear Antibody Epitopes on Factor H and CFHR1 Using Sera of Patients with Autoimmune Atypical Hemolytic Uremic Syndrome

Introduction: In autoimmune atypical hemolytic uremic syndrome (aHUS), the complement regulator factor H (FH) is blocked by FH autoantibodies, while 90% of the patients carry a homozygous deletion of its homolog complement FH-related protein 1 (CFHR1). The functional consequence of FH-blockade is widely established; however, the molecular basis of autoantibody binding and the role of CFHR1 deficiency in disease pathogenesis are still unknown. We performed epitope mapping of FH to provide structural insight in the autoantibody recruitment on FH and potentially CFHR1. Methods: Eight anti-FH positive aHUS patients were enrolled in this study. With overlapping synthetic FH and CFHR1 peptides, we located the amino acids (aa) involved in binding of acute and convalescence stage autoantibodies. We confirmed the location of the mapped epitopes using recombinant FH domains 19-20 that carried single-aa substitutions at the suspected antibody binding sites in three of our patients. Location of the linear epitopes and the introduced point mutations was visualized using crystal structures of the corresponding domains of FH and CFHR1. Results: We identified three linear epitopes on FH (aa1157-1171; aa1177-1191; and aa1207-1226) and one on CFHR1 (aa276-290) that are recognized both in the acute and convalescence stages of aHUS. We observed a similar extent of autoantibody binding to the aHUS-specific epitope aa1177-1191 on FH and aa276-290 on CFHR1, despite seven of our patients being deficient for CFHR1. Epitope mapping with the domain constructs validated the location of the linear epitopes on FH with a distinct autoantibody binding motif within aa1183-1198 in line with published observations. Summary: According to the results, the linear epitopes we identified are located close to each other on the crystal structure of FH domains 19-20. This tertiary configuration contains the amino acids reported to be involved in C3b and sialic acid binding on the regulator, which may explain the functional deficiency of FH in the presence of auto antibodies. The data we provide identify the exact structures involved in autoantibody recruitment on FH and confirm the presence of an autoantibody binding epitope on CFHR1.Peer reviewe

First-line therapy in atypical hemolytic uremic syndrome: consideration on infants with a poor prognosis.

BackgroundAtypical hemolytic uremic syndrome (aHUS) is a rare and heterogeneous disorder. The first line treatment of aHUS is plasma therapy, but in the past few years, the recommendations have changed greatly with the advent of eculizumab, a humanized monoclonal anti C5-antibody. Although recent recommendations suggest using it as a primary treatment for aHUS, important questions have arisen about the necessity of immediate use of eculizumab in all cases. We aimed to draw attention to a specific subgroup of aHUS patients with rapid disease progression and high mortality, in whom plasma therapy may not be feasible.MethodsWe present three pediatric patients of acute complement-mediated HUS with a fatal outcome. Classical and alternative complement pathway activity, levels of complement factors C3, C4, H, B and I, as well as of anti-factor H autoantibody and of ADAMTS13 activity were determined. The coding regions of CFH, CFI, CD46, THBD, CFB and C3 genes were sequenced and the copy number of CFI, CD46, CFH and related genes were analyzed.ResultsWe found severe activation and consumption of complement components in these patients, furthermore, in one patient we identified a previously not reported mutation in CFH (Ser722Stop), supporting the diagnosis of complement-mediated HUS. These patients were not responsive to the FFP therapy, and all cases had fatal outcome.ConclusionTaking the heterogeneity and the variable prognosis of atypical HUS into account, we suggest that the immediate use of eculizumab should be considered as first-line therapy in certain small children with complement dysregulation

Validation of distinct pathogenic patterns in a cohort of membranoproliferative glomerulonephritis patients by cluster analysis

Background: A novel data-driven cluster analysis identified distinct pathogenic patterns in C3-glomerulopathies and immune complex-mediated membranoproliferative glomerulonephritis. Our aim was to replicate these observations in an independent cohort and elucidate disease pathophysiology with detailed analysis of functional complement markers. ----- Methods: A total of 92 patients with clinical, histological, complement and genetic data were involved in the study, and hierarchical cluster analysis was done by Ward method, where four clusters were generated. ----- Results: High levels of sC5b-9 (soluble membrane attack complex), low serum C3 levels and young age at onset (13 years) were characteristic for Cluster 1 with a high prevalence of likely pathogenic variations (LPVs) and C3 nephritic factor, whereas for Cluster 2-which is not reliable because of the small number of cases-strong immunoglobulin G staining, low C3 levels and high prevalence of nephritic syndrome at disease onset were observed. Low plasma sC5b-9 levels, decreased C3 levels and high prevalence of LPV and sclerotic glomeruli were present in Cluster 3, and patients with late onset of the disease (median: 39.5 years) and near-normal C3 levels in Cluster 4. A significant difference was observed in the incidence of end-stage renal disease during follow-up between the different clusters. Patients in Clusters 3-4 had worse renal survival than patients in Clusters 1-2. ----- Conclusions: Our results confirm the main findings of the original cluster analysis and indicate that the observed, distinct pathogenic patterns are replicated in our cohort. Further investigations are necessary to analyse the distinct biological and pathogenic processes in these patient groups

C4 nephritic factor in patients with immune-complex-mediated membranoproliferative glomerulonephritis and C3-glomerulopathy

L

Tumor cell expression of Heat Shock Protein (HSP) 72 is influenced by HSP72 [HSPA1B A(1267)G] polymorphism and predicts Survival in Small Cell Lung Cancer (SCLC) patients

The inducible heat shock protein (HSP)72 plays a central role in antitumor immunomodulation. HSP72 expression was assessed on tumor samples of 43 patients with advanced and metastatic small cell lung cancer (SCLC) by immunohistochemistry and HSP72 [HSPA1B A(1267)G] polymorphism was determined. HSP72 expression of SCLC cells was significantly decreased in GG as compared to cells of AA or AG genotype patients, and was associated with significantly shorter survival in GG patients as compared to carriers of the A allele. Decreased HSP72 expression of SCLC cells associated with HSP72 GG genotype is a negative prognostic factor for survival in SCLC patients. © 2012 Informa Healthcare USA, Inc

Renin inhibition mitigates anti-angiogenesis in spontaneously hypertensive rats

Background Spontaneously hypertensive rats (SHRs) are characterized by capillary rarefaction, which may contribute to blood pressure elevation. We hypothesized that capillary rarefaction involves a suppressed angiogenesis; renin inhibition influences anti-angiogenesis homeostasis by acting on angiopoietins; transient renin blockade reduces anti-angiogenesis thereby ameliorating long-lasting blood pressure and cardiac hypertrophy in SHRs. Methods First, serum angiopoietin-1 and angiopoietin-2 were measured in 2-month old normotensive Wistar-Kyoto rats (WKYs) and SHRs after renin inhibition (aliskiren: 1 and 10mg/kg per day) or placebo. Second, 4-week old SHRs were prehypertensively treated with aliskiren (1 and 10mg/kg per day) or placebo for 4 weeks. After 4 weeks of 'drug holiday' 12-week old SHRs were given L-nitro-arginine methyl ester (L-NAME) (25mg/kg per day) for a 4-week interval to promote capillary rarefaction. Thereafter, mean arterial pressure (MAP), cardiacremodeling, capillary density, pAkt/Akt as marker for cellular survival, pro-angiogenic genes and systemic angiopoietins were investigated. Results Baseline angiopoietin levels were similar between WKYs and SHRs. Renin inhibition increased angiopoietin-1 in SHR and reduced angiopoietin-2 in both WKY and SHR blood pressure independently. Prehypertensive renin inhibition reduced MAP and cardiac hypertrophy in adult SHRs. This was associated with higher cardiac capillary density, pAkt/Akt, pro-angiogenic expression pattern and serum angiopoietin-1, whereas angiopoietin-2 was lower as compared to vehicle-pretreated SHRs. These results were independent of prehypertensive blood pressure lowering by aliskiren. Conclusion We conclude that renin inhibition modulates anti-angiogenesis signaling independently of blood pressure by increasing angiopoietin-1/angiopoietin-2 ratio. This promotes in SHR stabilization of endothelial cells, favors pro-angiogenic action and consequently results in higher capillary density. J Hypertens 29: 266-27