NFKB1 promoter polymorphism: A new predictive marker of cytomegalovirus infection after kidney transplantation.

INTRODUCTION: Cytomegalovirus (CMV) infection represents a common cause of morbidity and mortality in kidney transplant recipients (KTR). The NF-kB signaling pathway is highly involved in the pathogenesis of CMV infection. The -94ins/delATTG functional polymorphism in the promoter of NFKB1 has been associated with low intracellular levels of the protein and high incidence of inflammatory and autoimmune disease. In this study, we evaluated the association of this NFKB1 polymorphism with the risk of CMV infection. METHODS: CMV infection was defined as virus isolation or detection of viral antigens or nucleic acid in any body fluid or tissue specimen. Using Cox regression and survival analysis, we analyzed the association between the polymorphism and CMV infection as well as recurrence in the first 12 months after transplantation. RESULTS: We analyzed the -94ins/delATTG NFKB1 polymorphism of 189 KTRs. The 65% of CMV infections occurred in ins/ins group. Survival free from CMV infection was 54.7% for ins/ins group and 79.4% for deletion carriers one year after transplantation (P < 0.0001). At multivariate regression, deletion carriers showed a lower risk of CMV infection and recurrence with respect to ins/ins KTRs (HR = 0.224 P = 0.0002; HR = 0.307, P = 0.012, respectively). CONCLUSIONS: In conclusion, pretransplantation screening for NFKB1 -94ins/delATTG polymorphism may predict CMV infection and improve the management of patients at higher risk of infection in the post-transplant period.

Nerve growth factor exposure promotes tubular epithelial-mesenchymal transition via TGF-ß1 signaling activation.

Clinical studies showed that renal expression and serum levels of nerve growth factor (NGF) are increased in renal diseases characterized by progressive fibrosis, a pathologic process in which TGF-ß1 mediates most of the key events leading to tubular epithelial-mesenchymal transition (EMT). However, the pathogenic role of high NGF levels has not yet been elucidated. In this study, we found that in tubular renal cells, HK-2, NGF transcriptionally up-regulated TGF-ß1 expression and secretion and enhanced cell motility by activating EMT markers via its receptors, TrkA and p75(NTR). Interestingly, we observed that TGF-ß1-SMAD pathway activation and the up-regulation of EMT markers NGF-induced were both prevented when knockdown of TGF-ß1 gene occurred and that the pretreatment with an antibody anti-NGF reversed the nuclear translocation of pSMAD3/SMAD4 complex. Collectively, our results demonstrated that NGF promotes renal fibrosis via TGF-ß1-signaling activation, suggesting that in kidney diseases high NGF serum levels could contribute to worsen renal fibrosis.

[Semaglutide in Chronic Kidney Disease: Great Enthusiasm. But How Does It Work?] / La Semaglutide nella Malattia Renale Cronica: tanto entusiasmo. Ma come funziona?

Chronic Kidney Disease (CKD) is a clinical condition characterized by the progressive loss of kidney function. 10% of the world's population is affected by this condition, which represents the fifth leading cause of death globally. Furthermore, CKD is associated with increased risk of fatal and non-fatal cardiovascular events, and progression to end-stage renal disease. Over the last twenty years, an exponential growth in its prevalence and incidence has been observed. For this reason, various drugs have been developed and implemented in clinical practice, with various mechanisms, with the aim of reducing and minimizing this dramatic "cardio-renal" risk. These include SGLT2 inhibitors, mineralocorticoid receptor antagonists, and endothelin receptor antagonists. However, a large proportion of CKD patients do not respond sufficiently to these treatments. GLP-1 receptor agonists represent a class of antidiabetic and nephroprotective drugs that are very promising in improving the prognosis of patients with CKD, especially if associated with one of the above-mentioned classes. In this article, we discuss the direct and indirect mechanisms through which one of the GLP-1 agonists, semaglutide, ensures nephro- and cardioprotection in patients with CKD and type 2 diabetes.

Oxidative Balance and Inflammation in Hemodialysis Patients: Biomarkers of Cardiovascular Risk?

During chronic kidney disease, the progressive deterioration of renal function induces several biological/clinical dysfunctions, including enhancement of synthesis of inflammation/oxidative stress mediators. Impaired renal function is an independent cardiovascular risk factor; indeed, cardiovascular complications dominate the landscape of both chronic kidney disease and end-stage renal disease. The aim of this study is to explore the correlation between the global oxidative balance in hemodialysis patients and both inflammatory markers and cardiovascular events. Using photometric tests, this study explored plasmatic oxidative balance in 97 hemodialysis patients compared to a healthy population. In the hemodialysis patients, we showed that oxidative stress values were significantly lower than in controls while effectiveness in the antioxidant barrier was significantly increased in the hemodialysis group. Furthermore, we highlighted a strong correlation between oxidative index and blood levels of C-reactive protein. When patients were divided into two groups based on previous cardiovascular events, we found that subjects with previous cardiovascular events had higher values of both oxidative stress and antioxidant barrier than patients without cardiovascular events. Our results indicated that in hemodialysis patients, the clinical and prognostic significance of oxidative status is very different from general population. As cardiovascular complications represent a strong negative factor for survival of hemodialysis patients, the research of new cardiovascular risk biomarkers in these patients takes on particular importance in order to translate them into clinical practice/primary care.

Adiponectin secreted by tubular renal cells during LPS exposure worsens the cellular inflammatory damage.

The pathogenetic role of adiponectin (ADPN) in kidney failure is not yet elucidated, since in vitro and in vivo studies have demonstrated that ADPN exerts both anti-inflammatory and pro-inflammatory effects. Starting from our previous findings demonstrating that HK-2 cells express and secrete ADPN, in this study we investigated the autocrine role of ADPN in tubular inflammatory damage induced by lipopolysaccharide (LPS) and the underlying molecular mechanisms. Firstly, we observed that short-term exposure to LPS enhanced ADPN protein expression as well as the adiponectin receptor ADIPOR1 mRNA content together with its signaling pathway downstream, pAMPK/pERK/pJNK, whose up-regulation status was reversed when ADPN gene knockdown occurred. Interestingly, in the same experimental conditions, we observed that ADPN mediated the nuclear translocation of the transcription factors nuclear factor kappa B (NFkB) and pcFos/pcJun (activator protein 1, AP-1), both induced by the pJNK pathway and involved in tumor necrosis factor (TNF)-α transactivation. Indeed, by transient transfection assay, we observed that the LPS-induced increase of TNF-α promoter activity was abrogated in cells pretreated with the inhibitors of NFkB and AP-1. Collectively our results suggest that in HK-2 cells, ADPN produced upon LPS stimulus could worsen the inflammatory damage in an autocrine-dependent manner.

Early subclinical rejection treated with low dose i.v. steroids is not associated to graft survival impairment: 13-years' experience at a single center.

Subclinical rejection (SCR) has been variably associated with reduced graft survival, development and progression of interstitial fibrosis/tubular atrophy and chronic allograft nephropathy, but data are controversial concerning SCR treatment in terms of graft survival improvement. In this single-center retrospective study, we enrolled 174 adult kidney transplant recipients with a protocol biopsy performed at 30 days after transplantation to evaluate the incidence rate and risk factors for early SCR and its impact on 10-year graft survival. Five patients showed primary non function and were excluded. Among 159/169 (94.08 %) patients with stable graft function who underwent protocol biopsy, 17 (10.7 %) showed signs of SCR and were treated with low-dose intravenous (i.v.) steroids. Ten patients showed functional impairment, 8 (4.73 %) resulting as acute rejection. At multivariate analysis, donor age [odds ratio (OR) 1.04, 95 % confidence interval (CI) 1.01-1.09], and delayed graft function (DGF) (OR 1.08, 95 % CI 1.03-1.12) were significantly associated with SCR. The 10-year graft survival rate in the SCR group was similar to that in the normal-findings group (76.5 vs. 74.9 % respectively; p = 0.61). At multivariate Cox regression, acute [hazard ratio (HR) 5.22, 95 % CI 1.70-16.01], but not sub-clinical, rejection was independently associated with long-term graft failure. In conclusion, early protocol biopsy is a useful and safe tool to detect early SCR which seems not to affect the long-term survival. We suggest that this could be, probably, linked to early SCR treatment with low dose i.v. steroids.

Soluble Klotho levels in adult renal transplant recipients are modulated by recombinant human erythropoietin.

BACKGROUND: Data on serum soluble Klotho levels in chronic kidney disease are contradictory and even less is known after renal transplantation. Experimental studies demonstrated that recombinant human erythropoietin (rhEPO) treatment mitigates Klotho reduction caused by renal damage. Therefore, this study aimed to determine serum Klotho levels in a cohort of kidney transplant recipients (KTR) and to evaluate whether rhEPO treatment can modulate, in vivo and in vitro, soluble Klotho. METHODS: 117 KTR and 22 healthy subjects (HS) were enrolled. In 17 KTR, rhEPO was discontinued for 5 weeks and Klotho levels were compared to 34 propensity score-matched controls. Moreover, we evaluated Klotho mRNA expression and protein secretion in HK-2 tubular cells treated with cyclosporin A (CyA) and rhEPO, alone or in combination. RESULTS: Serum Klotho levels in KTR were significantly higher than in HS (0.68 vs. 0.37, p = 0.002) and significantly associated with estimated glomerular filtration rate (r = -0.378, p = 0.003) and fibroblast growth factor 23 (r = -0.307, p < 0.0001). After 5 weeks of rhEPO discontinuation, treated KTR showed a sharper reduction of Klotho levels than controls (-0.56 vs. -0.11 ng/ml, p < 0.0001). In HK-2 cells CyA treatment induced a Klotho down-regulation that was mitigated by rhEPO pre-treatment. In the same experimental conditions, our results revealed that cells treated with CyA + rhEPO secreted higher soluble Klotho levels than those exposed to CyA or rhEPO alone. CONCLUSIONS: Our results demonstrate that KTR have higher serum Klotho levels than HS and that rhEPO treatment modulates these concentrations, suggesting a link between rhEPO and soluble Klotho in KTR.

Exposure to nerve growth factor worsens nephrotoxic effect induced by Cyclosporine A in HK-2 cells.

Nerve growth factor is a neurotrophin that promotes cell growth, differentiation, survival and death through two different receptors: TrkA(NTR) and p75(NTR). Nerve growth factor serum concentrations increase during many inflammatory and autoimmune diseases, glomerulonephritis, chronic kidney disease, end-stage renal disease and, particularly, in renal transplant. Considering that nerve growth factor exerts beneficial effects in the treatment of major central and peripheral neurodegenerative diseases, skin and corneal ulcers, we asked whether nerve growth factor could also exert a role in Cyclosporine A-induced graft nephrotoxicity. Our hypothesis was raised from basic evidence indicating that Cyclosporine A-inhibition of calcineurin-NFAT pathway increases nerve growth factor expression levels. Therefore, we investigated the involvement of nerve growth factor and its receptors in the damage exerted by Cyclosporine A in tubular renal cells, HK-2. Our results showed that in HK-2 cells combined treatment with Cyclosporine A + nerve growth factor induced a significant reduction in cell vitality concomitant with a down-regulation of Cyclin D1 and up-regulation of p21 levels respect to cells treated with Cyclosporine A alone. Moreover functional experiments showed that the co-treatment significantly up-regulated human p21promoter activity by involvement of the Sp1 transcription factor, whose nuclear content was negatively regulated by activated NFATc1. In addition we observed that the combined exposure to Cyclosporine A + nerve growth factor promoted an up-regulation of p75 (NTR) and its target genes, p53 and BAD leading to the activation of intrinsic apoptosis. Finally, the chemical inhibition of p75(NTR) down-regulated the intrinsic apoptotic signal. We describe two new mechanisms by which nerve growth factor promotes growth arrest and apoptosis in tubular renal cells exposed to Cyclosporine A.

Adiponectin is expressed and secreted by renal tubular epithelial cells.

BACKGROUND: Adiponectin (ADPN) is predominantly produced by adipose tissue, and high ADPN levels have been detected in patients affected by proteinuric glomerulonephritis. In this study we investigate whether human tubular epithelial cells express and secrete ADPN. METHODS: In human proximal tubular epithelial cells, HK-2, ADPN mRNA was evaluated by real-time PCR assay, while protein expression levels were measured by Western blot analysis and immunofluorescence assay. Moreover, renal ADPN distribution was assessed by immunohistochemical analysis of kidney biopsy samples from healthy patients. Finally, by ELISA, we measured ADPN concentrations in culture media of HK-2 cells treated with 10 µg/mL lipopolysaccharide (LPS). RESULTS: Our analyses revealed that HK-2 cells express ADPN both in terms of mRNA and protein. These results were confirmed by the observed cytoplasmatic HK-2 intense immunoreactivity for ADPN antibody and by immunohistochemical analysis showing a diffuse ADPN distribution in normal kidney tissue. Furthermore, we observed that tubular cells secrete ADPN in the basal condition and, more interestingly, that this secretion significantly increases (p<0.05) upon LPS treatment in a time-dependent manner. Finally, immunohistochemical analysis of kidney biopsy samples obtained from patients affected by membranous and rapidly progressive glomerulonephritis showed a similar pattern of ADPN staining to that observed in healthy controls. CONCLUSIONS: Our study demonstrates for the first time that renal tubular cells express and secrete ADPN, and their concentration increases upon inflammatory stimulus. These results suggest that in renal inflammatory diseases, tubular cells may contribute to the increase in circulating ADPN levels, triggering a feedback response in order to self-mitigate the inflammatory process.