RESUMO
BACKGROUND: Fibrosis is a suggested cause of graft failure and mortality among kidney transplant recipients (KTRs). Accumulating evidence suggests that collagen type VI is tightly linked to fibrosis and may be a marker of systemic fibrosis and ageing. We studied whether plasma endotrophin, a pro-collagen type VI fragment, is associated with graft failure and mortality among KTRs. METHODS: In cohort A (57% male, age 53 ± 13 years), we measured plasma endotrophin in 690 prevalent KTRs ≥1 year after transplantation. The non-overlapping cohort B included 500 incident KTRs with serial endotrophin measurements before and after kidney transplantation to assess trajectories and intra-individual variation of endotrophin. RESULTS: In cohort A, endotrophin was higher in KTRs compared with healthy controls. Concentrations were positively associated with female sex, diabetes, cardiovascular disease, markers of inflammation and kidney injury. Importantly, endotrophin was associated with graft failure {hazard ratio [HR] per doubling 1.87 [95% confidence interval (CI) 1.07-3.28]} and mortality [HR per doubling 2.59 (95% CI 1.73-3.87)] independent of potential confounders. Data from cohort B showed that endotrophin concentrations strongly decrease after transplantation and remain stable during post-transplantation follow-up [intra-individual coefficient of variation 5.0% (95% CI 3.7-7.6)]. CONCLUSIONS: Plasma endotrophin is strongly associated with graft failure and mortality among KTRs. These findings suggest a key role of abnormal extracellular matrix turnover and fibrosis in graft and patient prognosis among KTRs and highlight the need for (interventional) studies targeting the profibrotic state of KTRs. The intra-individual stability after transplantation indicates potential use of endotrophin as a biomarker and outcome measure of fibrosis. TRIAL REGISTRATION: ClinicalTrials.gov NCT02811835.
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Colágeno Tipo VI , Rim , Humanos , Masculino , Feminino , Adulto , Pessoa de Meia-Idade , Idoso , Estudos Prospectivos , Rim/patologia , Fibrose , Fatores de RiscoRESUMO
BACKGROUND: This case report highlights a successful steroid-free, low-dose immunosuppressive protocol for renal transplantation in a pediatric patient with Schimke immuno-osseous dysplasia with excellent 7-year patient and graft survival. Schimke immuno-osseous dysplasia is a rare multisystem disorder involving the kidney. Renal transplantation is a therapeutic option, but posttransplant mortality is high due to severe infections and posttransplant lymphoproliferative disease. METHODS: A 10-year-old girl diagnosed with Schimke immuno-osseous dysplasia and end-stage renal disease underwent an AB0-compatible living-related kidney transplantation, with no donor-specific antibodies. Our standard immunosuppression protocol was modified due to the risk of infection. Basiliximab was used as induction therapy, and a reduced dose of mycophenolate mofetil and tacrolimus was initiated following transplantation, maintaining the patient on a low tacrolimus target (3-5 µg/L). Mycophenolate mofetil was discontinued after 8 weeks due to neutropenia and the patient was kept on tacrolimus as monotherapy. Five years posttransplant the patient developed acute onset of neurological symptoms, consisting of ataxia, lack of voluntary coordination, balance, aphasia and dysphagia, and diplopia. She recovered without neurological deficits within 6 weeks. Extensive evaluation revealed no pathology. To avoid a possible a component of tacrolimus-induced cerebral vasoconstriction, the immunosuppressive therapy was changed to everolimus. RESULTS: Seven years posttransplant, the patient has experienced no serious infections, no rejections, and had excellent graft function, and no de novo donor-specific antibodies. CONCLUSIONS: The present results indicate that low-dose immunosuppressive therapy after renal transplantation with low immunological risk should be considered for patients with Schimke immuno-osseous dysplasia.
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Transplante de Rim , Tacrolimo , Feminino , Humanos , Criança , Tacrolimo/uso terapêutico , Transplante de Rim/métodos , Ácido Micofenólico/uso terapêutico , Imunossupressores/uso terapêutico , Rejeição de Enxerto , ImunoterapiaRESUMO
BACKGROUND: Angiopoietin-2 (Ang-2) plays a pivotal role in pathological vascular remodeling and angiogenesis. Both vascular mechanisms are active in patients with end-stage renal disease (ESRD) and may contribute to the high mortality in these patients. The aim of this multicenter prospective cohort study was to investigate baseline serum Ang-2 concentrations in ESRD patients on hemodialysis (HD) for their ability to predict all-cause mortality. METHODS: We conducted a prospective cohort study in 340 stable HD patients from different chronic dialysis centers in Berlin, Germany. The primary endpoint was all-cause mortality during a 5-year follow-up period. Blood samples and clinical data were collected at baseline. Serum Ang-2 was measured with a validated enzyme-linked immunosorbent assay (Biomedica, Vienna, Austria). RESULTS: A total of 313 HD patients (206 men and 107 women) were finally included in the study. Receiver operating characteristic (ROC) analysis of Ang-2 concentrations yielded an area under the curve (AUC) of 0.65 (P < 0.0001) for predicting all-cause mortality in the entire study population and was used to determine the optimal cut-off (111.0 pmol/L) for all-cause mortality. Kaplan-Meier survival analysis indicated that male but not female end-stage kidney disease patients on HD with higher Ang-2 concentrations had a significantly lower survival (log-rank test, P < 0.0001 and P = 0.380 for male and female patients, respectively). Multivariable Cox regression analyses adjusted for age, comorbidity, smoking, dialysis vintage, serum creatinine, hemoglobin, C-reactive protein, serum albumin, intact parathyroid hormone (iPTH), low-density lipoprotein (LDL) and Kt/V likewise indicated that elevated Ang-2 concentrations are associated with all-cause mortality in male {hazard ratio [HR] 3.294 [95% confidence interval (CI) 1.768-6.138]; P = 0.0002} but not in female end-stage kidney disease patients on HD [HR 1.084 (95% CI 0.476-2.467); P = 0.847]. CONCLUSION: Ang-2 at baseline is independently associated with all-cause mortality in male ESRD patients on HD.
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Falência Renal Crônica , Diálise Renal , Angiopoietina-2 , Feminino , Humanos , Masculino , Modelos de Riscos Proporcionais , Estudos Prospectivos , Diálise Renal/efeitos adversosRESUMO
BACKGROUND: Atypical hemolytic uremic syndrome (aHUS) is a disorder of the microvasculature with hemolytic anemia, thrombocytopenia and acute kidney injury. Nowadays, aHUS is successfully treated with eculizumab, a humanized, chimeric IgG2/4 kappa antibody, which binds human complement C5 and blocks generation of C5a and membrane-attack-complex. CASE PRESENTATION: A 25-year-old woman with end stage renal disease due to relapsing atypical hemolytic uremic syndrome had a relapse of the disease during pregnancy. She was treated with eculizumab. We measured reduced formation of the membrane-attack complex in newborn's umbilical cord vein blood using the sensitive and specific Palarasah-Nielsen-ELISA. CONCLUSIONS: Eculizumab treatment of the mother with end stage renal disease may cause reduced innate immunity which could render newborns more susceptible to infections.
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Anticorpos Monoclonais Humanizados/uso terapêutico , Síndrome Hemolítico-Urêmica Atípica/tratamento farmacológico , Inativadores do Complemento/uso terapêutico , Complexo de Ataque à Membrana do Sistema Complemento/efeitos dos fármacos , Complicações na Gravidez/tratamento farmacológico , Adulto , Anticorpos Monoclonais Humanizados/metabolismo , Síndrome Hemolítico-Urêmica Atípica/imunologia , Complemento C3/metabolismo , Complemento C5a/metabolismo , Complemento C9/metabolismo , Inativadores do Complemento/metabolismo , Complexo de Ataque à Membrana do Sistema Complemento/metabolismo , Ensaio de Imunoadsorção Enzimática/métodos , Feminino , Sangue Fetal/imunologia , Humanos , Recém-Nascido , Falência Renal Crônica/tratamento farmacológico , Gravidez , RecidivaRESUMO
BACKGROUND/AIMS: Insulin signaling to podocytes is relevant for the function of the glomerulus. Now, we tested the hypothesis that insulin increases the surface expression of canonical transient receptor potential canonical type 6 (TRPC6) channels in podocytes by a calcineurin-dependent pathway. METHODS: We used quantitative RT-PCR, immunoblotting, immunofluorescence and fluorescence spectrophotometry in cultured podocytes. Activation of Nuclear Factor of Activated T-cells (NFATc1) was measured using a specific calorimetric assay. RESULTS: Insulin increased the expression of TRPC6 transcripts and protein in podocytes. Insulin increased TRPC6 transcripts in a time and dose-dependent manner. The insulin-induced elevation of TRPC6 transcripts was blocked in the presence of tacrolimus, cyclosporine A, and NFAT-inhibitor (each p < 0.01 by ANOVA and Bonferroni's multiple comparison test). Transcripts of NOX4, another target gene of the calcineurin-NFAT pathway, were affected in a similar way. Immunoblotting showed that the administration of 100 nmol/L insulin increased TRPC6-proteins 2-fold within 48 hours. Insulin increased the activity of NFATc1 in nuclear extracts (p < 0.001) whereas tacrolimus, cyclosporine A, and NFAT-inhibitor blocked that insulin effect (p < 0.001; two way ANOVA). Immunofluorescence showed that insulin increased TRPC6-expression on the cell surface. Fluorescence-spectrophotometry and manganese quench experiments indicated that the increased TRPC6-expression after insulin administration was accompanied by an elevated transplasmamembrane cation influx. Insulin-stimulated surface expression of TRPC6 as well as transplasmamembrane cation influx could be reduced by pretreatment with tacrolimus. CONCLUSION: Insulin increases the expression of TRPC6 channels in podocytes by activation of the calcineurin-dependent pathway.
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Calcineurina/metabolismo , Insulina/metabolismo , Podócitos/metabolismo , Transdução de Sinais , Canais de Cátion TRPC/genética , Regulação para Cima , Linhagem Celular , Humanos , Insulina/farmacologia , Podócitos/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos , Canais de Cátion TRPC/análise , Canal de Cátion TRPC6 , Ativação Transcricional/efeitos dos fármacos , Regulação para Cima/efeitos dos fármacosRESUMO
BACKGROUND: Tacrolimus is established as immunosuppressant after kidney transplantation. Polymorphism of the cytochrome P450 3A5 (CYP3A5) gene contributes significantly to tacrolimus dose requirements. Recently, CYP3A4*22 was reported to additionally affect tacrolimus pharmacokinetics (PK). In addition, there are further polymorphic genes, possibly influencing CYP3A activity [pregnane x receptor NR1I2, P450 oxidoreductase (POR), and peroxisome proliferator-activator receptor alpha (PPARA)]. We aimed to investigate combined effects of these gene variants on tacrolimus maintenance dose and PK in patients with stable kidney transplantation of 2 study centers. METHODS: A total of 223 white patients (German cohort, 136; Danish cohort, 87) was included and genotyped for CYP3A5 (rs776746), CYP3A4 (rs35599367), NR1I2 (rs2276707), POR (rs1057868), and PPARA (rs4253728). Dosage and trough concentration/dose ratios were considered separately. A subset was investigated for comprehensive PK parameters. RESULTS: Tacrolimus dose, trough concentration, and trough concentration/dose ratio did not differ between the German and Danish cohort. CYP3A5*3 and CYP3A4*22 contributed to dose requirements only in the German and in the total cohort. Homozygous carriers of both variants required 4.8 ± 3.1 mg, whereas carriers of the wild types required 165% higher mean tacrolimus doses (12.5 ± 7.7 mg, P = 1.4 × 10). The PK investigation revealed only nonsignificant impact of CYP3A4 genotypes on AUC12h in CYP3A5 nonexpressers (P = 0.079, power = 57%). For the entire sample, the final multiple linear regression model for trough concentration/dose ratio included CYP3A5, CYP3A4, and age. It explained 18.3% of the interindividual variability of tacrolimus trough concentration/dose ratios (P = 8.8 × 10). CONCLUSIONS: Therapeutic drug monitoring remains essential in clinical care of patients with kidney transplantation. Genotyping of CYP3A5 and CYP3A4, however, could facilitate rapid dose finding to adapt the appropriate immunosuppressant dose, whereas other genetic factors had only little or no effect.
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Citocromo P-450 CYP3A/genética , Transplante de Rim/métodos , Tacrolimo/administração & dosagem , Tacrolimo/farmacocinética , Sistema Enzimático do Citocromo P-450/genética , Monitoramento de Medicamentos/métodos , Feminino , Genótipo , Humanos , Imunossupressores/administração & dosagem , Imunossupressores/farmacocinética , Masculino , Pessoa de Meia-Idade , PPAR alfa/genética , Polimorfismo de Nucleotídeo Único/genética , Receptor de Pregnano X , Receptores de Esteroides/genéticaRESUMO
Transient receptor potential canonical (TRPC) channels type 6 play an important role in the function of human podocytes. Diabetic nephropathy is characterized by altered TRPC6 expression and functions of podocytes. Thus, we hypothesized that high glucose modifies TRPC6 channels via increased oxidative stress and syndecan-4 (SDC-4) in human podocytes. Human podocytes were exposed to control conditions (5.6 mmol/L D-glucose), high glucose (30 mmol/L D-glucose or L-glucose), 100 µmol/L peroxynitrite, or high glucose and the superoxide dismutase mimetic tempol (100 µmol/L). TRPC6 and SDC-4 transcripts and protein expression were measured using RT-PCR and in-cell Western assay. Intracellular reactive oxygen species (ROS) and cytosolic calcium were measured using fluorescent dye techniques. High D-glucose increased TRPC6 transcripts to 8.66±4.08 (p<0.05) and TRPC6 protein expression to 1.44±0.07 (p<0.05) without altering SDC-4 transcripts or protein expression. The D-glucose induced increase of TRPC6 expression was blocked by tempol. Increased oxidative stress using peroxynitrite significantly increased TRPC6 transcripts to 4.29±1.26 (p<0.05) and TRPC6 protein expression to 1.28±0.05 (p<0.05) without altering SDC-4 transcripts or protein expression. In human podocytes transfected with scrambled siRNA, high D-glucose increased ROS after 90 min to 3.55±0.08 arbitrary units while 5.6 mmol/L D-glucose increased ROS to 2.49±0.09 (p<0.001) only. The increase in ROS was inhibited by tempol and by SDC-4 knockdown. High glucose modifies TRPC6 channels and ROS production via SDC-4 in human podocytes.
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Sinalização do Cálcio/fisiologia , Glucose/administração & dosagem , Estresse Oxidativo/fisiologia , Oxigênio/metabolismo , Podócitos/metabolismo , Sindecana-4/metabolismo , Canais de Cátion TRPC/metabolismo , Sinalização do Cálcio/efeitos dos fármacos , Células Cultivadas , Relação Dose-Resposta a Droga , Humanos , Ativação do Canal Iônico/efeitos dos fármacos , Ativação do Canal Iônico/fisiologia , Estresse Oxidativo/efeitos dos fármacos , Podócitos/efeitos dos fármacos , Canais de Cátion TRPC/efeitos dos fármacos , Canal de Cátion TRPC6RESUMO
BACKGROUND: Uraemia and cardiovascular disease appear to be associated with an increased oxidative burden. One of the key players in the genesis of reactive oxygen species (ROS) is nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. Based on initial experiments demonstrating a decreased inhibitory effect on NADPH oxidase activity in the presence of plasma from patients with CKD-5D after dialysis compared with before dialysis, we investigated the effect of 48 known and commercially available uraemic retention solutes on the enzymatic activity of NADPH oxidase. METHODS: Mononuclear leucocytes isolated from buffy coats of healthy volunteers were isolated, lysed and incubated with NADH in the presence of plasma from healthy controls and patients with CKD-5D. Furthermore, the leucocytes were lysed and incubated in the presence of uraemic retention solute of interest and diphenyleneiodonium chloride (DPI), an inhibitor of NADPH oxidase. The effect on enzymatic activity of NADPH oxidase was quantified within an incubation time of 120 min. RESULTS: Thirty-nine of the 48 uraemic retention solutes tested had a significant decreasing effect on NADPH oxidase activity. Oxalate has been characterized as the strongest inhibitor of NADPH oxidase (90% of DPI inhibition). Surprisingly, none of the uraemic retention solutes we investigated was found to increase NADPH oxidase activity. Furthermore, plasma from patients with CKD-5D before dialysis caused significantly higher inhibitory effect on NADPH oxidase activity compared with plasma from healthy subjects. However, this effect was significantly decreased in plasma from patients with CKD-5D after dialysis. CONCLUSIONS: The results of this study show that uraemic retention solutes modulated the activity of the NADPH oxidase. The results of this study might be the basis for the development of inhibitors applicable as drug in the situation of increased oxidative stress.
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Fatores Biológicos/farmacologia , NADPH Oxidases/metabolismo , Insuficiência Renal Crônica/enzimologia , Uremia/enzimologia , Adulto , Feminino , Voluntários Saudáveis , Humanos , Leucócitos Mononucleares/enzimologia , Masculino , Estresse Oxidativo/fisiologia , Plasma/fisiologia , Espécies Reativas de Oxigênio/farmacologia , Diálise Renal , Insuficiência Renal Crônica/terapiaRESUMO
Background: Progressive decline of allograft function leads to premature graft loss. Forkhead box P3 (FOXP3), a characteristic gene of T-regulatory cells, is known to be essential for auto-antigen tolerance. We assessed the hypothesis that low FOXP3 mRNA splice variant levels in peripheral blood cells early after transplantation are associated with progressive allograft injury. Methods: Blood samples were prospectively collected from 333 incident kidney transplant recipients on the first and 29th postoperative day. We used quantitative polymerase chain reaction to determine transcripts of 3 isotypes of FOXP3 splice variants, including pre-mature FOXP3 and full length FOXP3 (FOXP3fl). We investigated the association between FOXP3 splice variant levels and the declines in estimated glomerular filtration rate (eGFR) of more than 5ml/min/1.73m2 within the first-year post-transplant using logistic regression. Results: We observed lower FOXP3fl levels in recipients with declining eGFR (N = 132) than in recipients with stable eGFR (N = 201), (logarithmic value -4.13 [IQR -4.50 to -3.84] vs -4.00 [4.32 to -3.74], p=0.02). In ad hoc analysis pre-transplant FOXP3fl levels were similar in both groups. The association between FOXP3fl and declining eGFR was confirmed by multivariable analysis adjusted for potential confounding factors (Odds Ratio 0.51, 95% confidence interval 0.28 to 0.91: p=0.02). When stratifying FOXP3fl levels into quartiles, recipients with lower day1 FOXP3fl had the highest rate of declining eGFR (p=0.04). Conclusion: Low FOXP3fl splice variant levels at the first postoperative day in kidney transplant recipients were associated with severe decline of eGFR, a well-known surrogate for hard endpoints.
Assuntos
Fatores de Transcrição Forkhead , Transplante de Rim , Tolerância ao Transplante , Feminino , Humanos , Masculino , Aloenxertos/imunologia , Processamento Alternativo , Fatores de Transcrição Forkhead/genética , Taxa de Filtração Glomerular , Rejeição de Enxerto/imunologia , Rejeição de Enxerto/genética , Transplante de Rim/efeitos adversos , Isoformas de Proteínas/genética , Tolerância ao Transplante/genéticaRESUMO
Peripheral blood mononuclear cells contain secretory granules with Perforin and Granzyme B for defense against pathogens. The objective of the present study was to compare the effects of immunosuppressive induction therapies on Perforin and Granzyme B transcripts in kidney transplant recipients. Transcripts were determined in 408 incident kidney transplant recipients eight days posttransplant using quantitative real-time PCR. Compared to 90 healthy subjects, the median Perforin transcripts were lower in kidney transplant recipients with blood-group ABO-incompatible donors (N = 52), compatible living donors (N = 130), and deceased donors (N = 226) (25.7%; IQR, 6.5% to 46.0%; 31.5%; IQR, 10.9% to 57.7%; and 35.6%; IQR, 20.6% to 60.2%; respectively; p = 0.015 by the Kruskal-Wallis test). Kidney transplant recipients who were treated with thymoglobulin (N = 64) had significantly lower Perforin as well as Granzyme B compared to all other induction therapies (N = 344) (each p < 0.001). Receiver operator characteristics analysis showed that both Perforin (area under curve, 0.919) and Granzyme B (area under curve, 0.915) indicated thyroglobulin-containing induction therapies. Regression analysis showed that both reduction in plasma creatinine and human leukocyte antigen mismatches were positively associated with elevated Perforin/Granzyme B transcript ratio posttransplant. We conclude clinical parameters and therapies affect Perforin and Granzyme B transcripts posttransplant.
RESUMO
The forkhead box P3 (FOXP3) transcript is essential for tolerance of alloantigens. Here, we describe the expression of FOXP3 mRNA variants in healthy females and males, and in kidney transplant recipients (KTR). We measured FOXP3 in peripheral blood mononuclear cells from healthy kidney donors (N = 101), and in blood from KTRs (N = 248) before and after transplantation. FOXP3 was measured with quantitative polymerase chain reaction, and differentiated between pre-mature mRNA FOXP3, Total mature FOXP3, FOXP3 in which exon two is spliced, and full length FOXP3. We found similar levels of FOXP3 in healthy female and male kidney donors. We confirmed this result in a publicly available cohort (N = 33) of healthy individuals (GSE97475). Homogenously, female and male KTR FOXP3 levels were similar pre-transplantation, one day post-transplantation and 29 days post-transplantation. This may suggest that kidney transplantation and related immunosuppressive treatments do not influence FOXP3 expression differently in females and males. Finally, fold difference analysis revealed that KTRs express lower levels of mature FOXP3 and higher levels of pre-mature FOXP3 mRNA pre-transplant compared to healthy individuals. This finding may suggest higher pre-mRNA synthesis, lower pre-mRNA degradation, lower spliceosome efficiency or higher degradation of mature FOXP3 mRNA in kidney transplant candidates.
Assuntos
Fatores de Transcrição Forkhead , Transplante de Rim , Humanos , Transplante de Rim/efeitos adversos , Fatores de Transcrição Forkhead/genética , Fatores de Transcrição Forkhead/metabolismo , Masculino , Feminino , Adulto , Pessoa de Meia-Idade , Transplantados , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Processamento Alternativo , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Leucócitos Mononucleares/metabolismo , IdosoRESUMO
INTRODUCTION: Periostin is a matricellular protein. Elevated serum concentrations of periostin have been reported in patients with various cardiovascular diseases, including heart failure. Patients with end-stage renal disease have a substantially increased risk for cardiovascular diseases. However, there is a lack of clinical studies to clarify the prognostic significance of systemic periostin on all-cause mortality in patients with end-stage renal disease on hemodialysis. METHODS: 313 stable end-stage renal disease patients were recruited and followed for 5 years concerning all-cause mortality. At baseline, we collected blood samples and clinical data. Serum periostin concentrations were measured using a certified ELISA. RESULTS: The optimal cut-off value for serum periostin regarding all-cause mortality, calculated through receiver operating characteristic analysis, was 777.5 pmol/L. Kaplan-Meier survival analysis using this cut-off value demonstrated that higher periostin concentrations are linked to higher all-cause mortality (log-rank test: p = 0.002). Subgroup analysis revealed that serum periostin concentrations only affected all-cause mortality in male but not in female patients (p = 0.002 in male patients and p = 0.474 in female patients). Multivariate Cox regression analyses, adjusted for confounding factors, likewise showed that elevated serum periostin concentrations were positively associated with all-cause mortality in male (p = 0.028) but not in female patients on hemodialysis (p = 0.313). CONCLUSION: Baseline serum periostin is an independent risk factor for all-cause mortality in male patients with chronic renal disease on hemodialysis.
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Moléculas de Adesão Celular , Falência Renal Crônica , Diálise Renal , Humanos , Moléculas de Adesão Celular/sangue , Feminino , Falência Renal Crônica/terapia , Falência Renal Crônica/mortalidade , Falência Renal Crônica/sangue , Falência Renal Crônica/complicações , Masculino , Pessoa de Meia-Idade , Idoso , Fatores Sexuais , Prognóstico , Causas de Morte/tendências , Biomarcadores/sangue , Fatores de Risco , Curva ROC , Estimativa de Kaplan-Meier , PeriostinaRESUMO
BACKGROUND: The renal proximal tubule (RPT) plays a pivotal role in regulating sodium reabsorption and thus blood pressure (BP). Transient receptor potential ankyrin 1 (TRPA1) has been reported to protect against renal injury by modulating mitochondrial function. We hypothesize that the activation of TRPA1 by its agonist cinnamaldehyde may mitigate high-salt intake-induced hypertension by inhibiting urinary sodium reabsorption through restoration of renal tubular epithelial mitochondrial function. METHODS: Trpa1-deficient (Trpa1-/-) mice and wild-type (WT) mice were fed standard laboratory chow [normal diet (ND) group, 0.4% salt], standard laboratory chow with 8% salt [high-salt diet (HS) group], or standard laboratory chow with 8% salt plus 0.015% cinnamaldehyde [high-salt plus cinnamaldehyde diet (HSC) group] for 6 months. Urinary sodium excretion, reactive oxygen species (ROS) production, mitochondrial function, and the expression of sodium hydrogen exchanger isoform 3 (NHE3) and Na+/K+-ATPase of RPTs were determined. RESULTS: Chronic dietary cinnamaldehyde supplementation reduced tail systolic BP and 24-hour ambulatory arterial pressure in HS-fed WT mice. Compared with the mice fed HS, cinnamaldehyde supplementation significantly increased urinary sodium excretion, inhibited excess ROS production, and alleviated mitochondrial dysfunction of RPTs in WT mice. However, these effects of cinnamaldehyde were absent in Trpa1-/- mice. Furthermore, chronic dietary cinnamaldehyde supplementation blunted HS-induced upregulation of NHE3 and Na+/K+-ATPase in WT mice but not Trpa1-/- mice. CONCLUSIONS: The present study demonstrated that chronic activation of Trpa1 attenuates HS-induced hypertension by inhibiting urinary sodium reabsorption through restoring renal tubular epithelial mitochondrial function. Renal TRPA1 may be a potential target for the management of excessive dietary salt intake-associated hypertension.
Assuntos
Acroleína , Hipertensão , Camundongos Knockout , Mitocôndrias , Cloreto de Sódio na Dieta , Canal de Cátion TRPA1 , Animais , Canal de Cátion TRPA1/metabolismo , Canal de Cátion TRPA1/genética , Acroleína/análogos & derivados , Acroleína/farmacologia , Hipertensão/metabolismo , Hipertensão/fisiopatologia , Mitocôndrias/metabolismo , Mitocôndrias/efeitos dos fármacos , Masculino , Camundongos Endogâmicos C57BL , ATPase Trocadora de Sódio-Potássio/metabolismo , Modelos Animais de Doenças , Espécies Reativas de Oxigênio/metabolismo , Trocador 3 de Sódio-Hidrogênio/metabolismo , Trocador 3 de Sódio-Hidrogênio/genética , Túbulos Renais Proximais/metabolismo , Túbulos Renais Proximais/efeitos dos fármacos , Camundongos , Pressão Sanguínea/efeitos dos fármacosRESUMO
OBJECTIVE: Syndecan 4 (Sdc4) modulates signal transduction and regulates activity of protein channels. Sdc4 is essential for the regulation of cellular permeability. We hypothesized that Sdc4 may regulate transient receptor potential canonical 6 (TRPC6) channels, a determinant of glomerular permeability, in a RhoA/Rho-associated protein kinase-dependent manner. METHODS AND RESULTS: Sdc4 knockout (Sdc4(-/-)) mice showed increased glomerular filtration rate and ameliorated albuminuria under baseline conditions and after bovine serum albumin overload (each P<0.05). Using reverse transcription-polymerase chain reaction and immunoblotting, Sdc4(-/-) mice showed reduced TRPC6 mRNA by 79% and TRPC6 protein by 82% (each P<0.05). Sdc4(-/-) mice showed an increased RhoA activity by 87% and increased phosphorylation of ezrin in glomeruli by 48% (each P<0.05). Sdc4 knockdown in cultured podocytes reduced TRPC6 gene expression and reduced the association of TRPC6 with plasma membrane and TRPC6-mediated calcium influx and currents. Sdc4 knockdown inactivated negative regulatory protein Rho GTPase activating protein by 33%, accompanied by a 41% increase in RhoA activity and increased phosphorylation of ezrin (P<0.05). Conversely, overexpression of Sdc4 reduced RhoA activity and increased TRPC6 protein and TRPC6-mediated calcium influx and currents. CONCLUSIONS: Our results establish a previously unknown function of Sdc4 for regulation of TRPC6 channels and support the role of Sdc4 for the regulation of glomerular permeability.
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Podócitos/fisiologia , Transdução de Sinais/fisiologia , Sindecana-4/fisiologia , Canais de Cátion TRPC/fisiologia , Proteínas rho de Ligação ao GTP/fisiologia , Quinases Associadas a rho/fisiologia , Animais , Cálcio/fisiologia , Membrana Celular/fisiologia , Células Cultivadas , Taxa de Filtração Glomerular/fisiologia , Córtex Renal/citologia , Camundongos , Camundongos Knockout , Modelos Animais , Podócitos/citologia , Sindecana-4/deficiência , Sindecana-4/genética , Canal de Cátion TRPC6 , Proteína rhoA de Ligação ao GTPRESUMO
: Recent studies indicate that transient receptor potential canonical type 3 (TRPC3) channels contribute to the regulation of blood pressure and vascular and renal function. Several studies show that TRPC3 dysfunction is associated with hypertension, atherosclerosis, cardiac hypertrophy, and cerebrovascular events. In this review, we summarize the role of TRPC3 channels in the cardiovascular system, and we focus on their pathophysiological role in hypertension and related target organ damages. We provide new insight into the involvement of TRPC3 channels in the development of hypertension and its related complications.
Assuntos
Hipertensão/fisiopatologia , Canais de Cátion TRPC/fisiologia , Pressão Sanguínea/fisiologia , Sistema Cardiovascular , Humanos , Hipertensão/complicaçõesRESUMO
BACKGROUND: The biological properties of oxidized and non-oxidized PTH are substantially different. Oxidized PTH (oxPTH) loses its PTH receptor-stimulating properties, whereas non-oxidized PTH (n-oxPTH) is a full agonist of the receptor. This was described in more than 20 well published studies in the 1970(s) and 80(s). However, PTH oxidation has been ignored during the development of PTH assays for clinical use so far. Even the nowadays used third generation assay systems do not consider oxidation of PTH We recently developed an assay to differentiate between oxPTH and n-oxPTH. In the current study we established normal values for this assay system. Furthermore, we compare the ratio of oxPTH to n-oxPTH in different population with chronic renal failure: 620 children with renal failure stage 2-4 of the 4C study, 342 adult patients on dialysis, and 602 kidney transplant recipients. In addition, we performed modeling of the interaction of either oxPTH or n-oxPTH with the PTH receptor using biophysical structure approaches. RESULTS: The children had the highest mean as well as maximum n-oxPTH concentrations as compared to adult patients (both patients on dialysis as well as kidney transplant recipients). The relationship between oxPTH and n-oxPTH of individual patients varied substantially in all three populations with renal impairment. The analysis of n-oxPTH in 89 healthy control subjects revealed that n-oxPTH concentrations in patient with renal failure were higher as compared to healthy adult controls (2.25-fold in children with renal failure, 1.53-fold in adult patients on dialysis, and 1.56-fold in kidney transplant recipients, respectively). Computer assisted biophysical structure modeling demonstrated, however, minor sterical- and/or electrostatic changes in oxPTH and n-oxPTH. This indicated that PTH oxidation may induce refolding of PTH and hence alters PTH-PTH receptor interaction via oxidation induced three-dimensional structure alteration of PTH. CONCLUSION: A huge proportion of circulating PTH measured by current state-of-the-art assay systems is oxidized and thus not biologically active. The relationship between oxPTH and n-oxPTH of individual patients varied substantially. Non-oxidized PTH concentrations are 1.5 - 2.25 fold higher in patients with renal failure as compared to health controls. Measurements of n-oxPTH may reflect the hormone status more precise. The iPTH measures describes most likely oxidative stress in patients with renal failure rather than the PTH hormone status. This, however, needs to be demonstrated in further clinical studies. © 2013 S. Karger AG, Basel.
Assuntos
Falência Renal Crônica/sangue , Transplante de Rim , Modelos Moleculares , Receptor Tipo 1 de Hormônio Paratireóideo/sangue , Diálise Renal , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Biomarcadores/sangue , Criança , Pré-Escolar , Estudos de Coortes , Feminino , Humanos , Falência Renal Crônica/terapia , Masculino , Pessoa de Meia-Idade , Oxirredução , Estudos Prospectivos , Ligação Proteica/fisiologia , Adulto JovemRESUMO
Background and aims: Outcome trials using sodium glucose cotransporter type 2 inhibitors have consistently shown their potential to preserve kidney function in diabetic and nondiabetic patients. Several mechanisms have been introduced which may explain the nephroprotective effect of sodium glucose cotransporter type 2 inhibitors beyond lowering blood glucose. This current narrative review has the objective to describe main underlying mechanisms causing a nephroprotective effect and to show similarities as well as differences between proposed mechanisms which can be observed in patients with diabetic and nondiabetic chronic kidney disease. Methods: We performed a narrative review of the literature on Pubmed and Embase. The research string comprised various combinations of items including "chronic kidney disease", "sodium glucose cotransporter 2 inhibitor" and "mechanisms". We searched for original research and review articles published until march, 2022. The databases were searched independently and the agreements by two authors were jointly obtained. Results: Sodium glucose cotransporter type 2 inhibitors show systemic, hemodynamic, and metabolic effects. Systemic effects include reduction of blood pressure without compensatory activation of the sympathetic nervous system. Hemodynamic effects include restoration of tubuloglomerular feedback which may improve pathologic hyperfiltration observed in most cases with chronic kidney disease. Current literature indicates that SGLT2i may not improve cortical oxygenation and may reduce medullar oxygenation. Conclusion: Sodium glucose cotransporter type 2 inhibitors cause nephroprotective effects by several mechanisms. However, several mediators which are involved in the underlying pathophysiology may be different between diabetic and nondiabetic patients.
Assuntos
Diabetes Mellitus Tipo 2 , Nefropatias Diabéticas , Insuficiência Renal Crônica , Inibidores do Transportador 2 de Sódio-Glicose , Humanos , Nefropatias Diabéticas/tratamento farmacológico , Nefropatias Diabéticas/etiologia , Nefropatias Diabéticas/prevenção & controle , Hipoglicemiantes/uso terapêutico , Hipoglicemiantes/farmacologia , Inibidores do Transportador 2 de Sódio-Glicose/uso terapêutico , Inibidores do Transportador 2 de Sódio-Glicose/farmacologia , Insuficiência Renal Crônica/complicações , Insuficiência Renal Crônica/tratamento farmacológico , Insuficiência Renal Crônica/metabolismo , Diabetes Mellitus Tipo 2/complicações , Diabetes Mellitus Tipo 2/tratamento farmacológico , Proteínas de Transporte de Sódio-GlucoseRESUMO
Background: Immunosuppressive treatment of kidney transplant recipients is mainly aimed at pro-inflammatory T effector cells, yet they also target the immunosuppressive T regulatory cells. Here, we test the hypothesis that low levels of the master gene regulator of T regulatory cells, forkhead box P3 (FOXP3) splice variants, are associated with prolonged inflammatory responses to stimuli. Methods: From blood samples obtained the first - and 29th day post-transplant, we extracted peripheral blood mononuclear cells and measured mRNA levels of Total FOXP3, pre-mature RNA FOXP3 (pre-mRNA FOXP3), full length FOXP3 (FOXP3fl) and, FOXP3 splice variant excluding exon two (FOXP3d2). We defined the primary outcome as the number of days in which C reactive protein (CRP) was above 50 mg/L. CRP levels were gathered in two periods, the first from the second to 29 days post-transplant, and the second from 30 to 57 days post-transplant. The association was tested using adjusted negative binomial regression. Results: From 507 included kidney transplant recipients, 382 recipients had at least one CRP measurement >50 mg/L in the first period, median duration of elevated CRP was 4 days [interquartile range (IQR) 2 to 6]. In the second period, 69 recipients had at least one CRP measurement >50 mg/L, median duration of elevated CRP was 3 days [IQR 2 to 5]. In the first period, we found a significant association between lower levels of Total FOXP3 and prolonged duration of CRP elevation, incidence rate ratio 0.61 (95% confidence interval 0.46-0.80), p<0.01. Conclusion: Lower levels of total FOXP3 mRNA levels in peripheral blood of kidney transplant recipients are associated with prolonged duration of inflammatory responses regardless of the underlying stimuli.
RESUMO
Forkhead Box P3 (FOXP3) is crucial for the development and suppressive function of human regulatory T cells (Tregs). There are two predominant FOXP3 splicing isoforms in healthy humans, the full-length isoform and the isoform lacking exon 2, with different functions and regulation mechanisms. FOXP3 splicing isoforms show distinct abilities in the cofactor interaction and the nuclear translocation, resulting in different effects on the differentiation, cytokine secretion, suppressive function, linage stability, and environmental adaptation of Tregs. The balance of FOXP3 splicing isoforms is related to autoimmune diseases, inflammatory diseases, and cancers. In response to environmental challenges, FOXP3 transcription and splicing can be finely regulated by T cell antigen receptor stimulation, glycolysis, fatty acid oxidation, and reactive oxygen species, with various signaling pathways involved. Strategies targeting energy metabolism and FOXP3 splicing isoforms in Tregs may provide potential new approaches for the treatment of autoimmune diseases, inflammatory diseases, and cancers. In this review, we summarize recent discoveries about the FOXP3 splicing isoforms and address the metabolic regulation and specific functions of FOXP3 splicing isoforms in Tregs.
Assuntos
Doenças Autoimunes , Neoplasias , Humanos , Processamento Alternativo , Doenças Autoimunes/genética , Fatores de Transcrição Forkhead/metabolismo , Neoplasias/genética , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismoRESUMO
Early prediction of kidney graft function may assist clinical management, and for this, reliable non-invasive biomarkers are needed. We evaluated endotrophin (ETP), a novel non-invasive biomarker of collagen type VI formation, as a prognostic marker in kidney transplant recipients. ETP levels were measured with the PRO-C6 ELISA in the plasma (P-ETP) of 218 and urine (U-ETP/Cr) of 172 kidney transplant recipients, one (D1) and five (D5) days, as well as three (M3) and twelve (M12) months, after transplantation. P-ETP and U-ETP/Cr at D1 (P-ETP AUC = 0.86, p < 0.0001; U-ETP/Cr AUC = 0.70, p = 0.0002) were independent markers of delayed graft function (DGF) and P-ETP at D1 had an odds ratio of 6.3 (p < 0.0001) for DGF when adjusted for plasma creatinine. The results for P-ETP at D1 were confirmed in a validation cohort of 146 transplant recipients (AUC = 0.92, p < 0.0001). U-ETP/Cr at M3 was negatively associated with kidney graft function at M12 (p = 0.007). This study suggests that ETP at D1 can identify patients at risk of delayed graft function and that U-ETP/Cr at M3 can predict the future status of the allograft. Thus, measuring collagen type VI formation could aid in predicting graft function in kidney transplant recipients.