Enfermedad renal crónica: la carga sanitaria invisible para los organismos

The uptake of the current concept of chronic kidney disease (CKD) by the public, physicians and health authorities is low. Physicians still mix up CKD with chronic kidney insufficiency or failure. In a recent manuscript, only 23% of participants in a cohort of persons with CKD had been diagnosed by their physicians as having CKD while 29% has a diagnosis of cancer and 82% had a diagnosis of hypertension. For the wider public and health authorities, CKD evokes kidney replacement therapy (KRT). In Spain, the prevalence of KRT is 0.13%. A prevalent view is that for those in whom kidneys fail, the problem is “solved” by dialysis or kidney transplantation. However, the main burden of CKD is accelerated aging and allcause and cardiovascular premature death. CKD is the most prevalent risk factor for lethal COVID-19 and the factor that most increases the risk of death in COVID-19, after old age. Moreover, men and women undergoing KRT still have an annual mortality which is 10–100- fold higher than similar age peers, and life expectancy is shortened by around 40 years for young persons on dialysis and by 15 years for young persons with a functioning kidney graft. CKD is expected to become the fifth global cause of death by 2040 and the second cause of death in Spain before the end of the century, a time when 1 in 4 Spaniards will have CKD. However, by 2022, CKD will become the only top-15 global predicted cause of death that is not supported by a dedicated well-funded CIBER network research structure in Spain. Leading Spanish kidney researchers grouped in the kidney collaborative research network REDINREN have now applied for the RICORS call of collaborative research in Spain with the support of the Spanish Society of Nephrology, ALCER and ONT: RICORS2040 aims to prevent the dire predictions for the global 2040 burden of CKD from becoming true. However, only the highest level of research funding through the CIBER will allow to adequately address the issue before it is too lateEl impacto del concepto actual de enfermedad renal crónica (ERC) en la población, médicos y autoridades sanitarias ha sido bajo. Los médicos aún confunden la ERC con la insuficiencia renal crónica. En un manuscrito reciente, en una cohorte de personas con ERC, solo el 23% de los participantes fueron diagnosticados de ERC por sus médicos mientras que el 29% estaban diagnosticados de cáncer y el 82% de hipertensión. Para el público en general y las autoridades sanitarias, la ERC evoca la terapia de reemplazo renal (TRR). En España, la prevalencia de TRR es del 0,13%. La opinión predominante es que para aquellos en los que fallan los riñones el problema se “resuelve” mediante diálisis o trasplante de riñón. Sin embargo, la principal carga sanitaria de la ERC es el envejecimiento acelerado y la muerte prematura de causa cardiovascular o de cualquier causa. La ERC es el factor mas prevalente de riesgo de mortalidad por COVID-19 después de la edad avanzada. Además, los hombres y mujeres que se someten a TRR todavía tienen una mortalidad anual que es de 10 a 100 veces superior a sus pares de edades similares, y la esperanza de vida se reduce en alrededor de 40 años para jóvenes en diálisis y en 15 años para jóvenes con un injerto renal funcionante. Se espera que la ERC se convierta en la quinta causa mundial de muerte para 2040 y la segunda causa de muerte en España antes de fin de siglo, época en la que 1 de cada 4 españoles tendrá ERC. Sin embargo, para 2022, la ERC se convertirá en la única causa de muerte entre las 15 principales a nivel mundial que no cuenta con el respaldo de una estructura de investigación CIBER en España. Los Principales grupos de investigación renal en España agrupados en la red de investigación colaborativa renal REDINREN han solicitado la convocatoria RICORS de investigación colaborativa en España con el apoyo de la Sociedad Española de Nefrología, ALCER y ONT: RICORS 040 tiene como objetivo evitar que se hagan realidad las terribles predicciones sobre la carga mundial de ERC para 2040. Sin embargo, solo el más alto nivel de financiación de la investigación a través del CIBER permitirá abordar adecuadamente el problema antes de que sea demasiado tard

El receptor del factor de crecimiento epidérmico (EGFR): Nueva diana terapéutica en la patología renal

Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Medicina, Departamento de Bioquímica. Fecha de lectura: 19-06-2015La mayor parte de las enfermedades renales crónicas (ERC) se caracterizan por una inflamación crónica y una fibrosis progresiva, que conduce a una insuficiencia renal terminal. Existen diferentes factores/mediadores que participan en la progresión de la ERC, entre los que destacan CCN2, PTHrP y TWEAK. El EGFR es un receptor de membrana de tipo tirosina quinasa que se expresa en glomérulo y túbulointersticio renal. Estudios previos han descrito el papel clave del EGFR en la progresión de la fibrosis renal. Sin embargo, no existen apenas datos concluyentes sobre su papel en el proceso inflamatorio. El objetivo general de esta tesis es determinar la contribución de la vía del EGFR en el daño renal experimental, investigando sus efectos en los procesos de inflamación y fibrosis, y evaluando los mecanismos intracelulares implicados, con el fin de mejorar las estrategias terapéuticas actuales empleadas en pacientes con ERC. La activación del EGFR se puede producir mediante activación directa o mediante “transactivación”, esta última dependiente de MMPs/ADAMs. Los resultados de esta tesis han demostrado que CCN2 es un nuevo ligando del EGFR que se une directamente a este receptor y lo activa, de forma independiente de MMPs/ADAMs. Por otro lado, diversos factores implicados en el daño renal, tales como PTHrP y TWEAK, desencadenan la transactivación del EGFR en el riñón. Los mecanismos implicados en la transactivación del EGFR inducida por PTHrP, vía el receptor acoplado a proteínas G PTH1R, incluyen MMPs, PKC y Src. Por otro lado, TWEAK, mediante su interacción con su receptor Fn14, transactiva el EGFR por activación de ADAM17 y liberación de los ligandos HB-EGF y TGF-α. Estudios experimentales previos sugieren que el bloqueo de la vía del EGFR podría ser una diana antifibrótica en la patología renal. En estudios in vitro hemos observado que la activación directa del EGFR por CCN2, y la transactivación de esta ruta por PTHrP es capaz de regular los eventos asociados a la transición epitelio mesenquimal, proceso que contribuye a la fibrogénesis renal. Los resultados obtenidos en esta tesis estudiando los modelos experimentales de daño renal por administración sistémica de CCN2(IV) o de TWEAK en ratón, demuestran que la activación de la vía del EGFR se asocia a un proceso inflamatorio que se previene con el bloqueo farmacológico de esta ruta. El bloqueo de la transactivación del EGFR inducida por TWEAK modulando el eje ADAM17/EGFR, disminuyó la respuesta inflamatoria, sugiriendo que el bloqueo de este eje podría ser una buena opción terapéutica para enfermedades inflamatorias renales. La enfermedad renal crónica se caracteriza por una deficiencia en los niveles de vitamina D. Diversos datos experimentales demuestran que los agonistas del receptor de vitamina D (VDRAs) ejercen efectos antinflamatorios beneficiosos en ERC. En esta tesis hemos observado que el tratamiento con el VDRA Paricalcitol inhibió la transactivación del EGFR inducida por TWEAK así como la activación de mecanismos intracelulares posteriores, incluyendo la sobreexpresión de factores proinflamatorios y la presencia de células infiltrantes en el riñón. El factor de trascripción NF-κB juega un papel clave en la regulación de la respuesta inflamatoria renal. TWEAK es una de las pocas citoquinas que activa la vía canónica y la no canónica de NF-κB. El bloqueo de la trasactivación de EGFR inducido por TWEAK mediante diferentes abordajes farmacológicos, como Paricalcitol, no inhibió la activación de la vía canónica de NF-κB1 mientras que si bloqueó la activación de la vía no canónica NF-κB2 y la inducción de quimioquinas específicas de esta ruta. Estos resultados muestran un nuevo mecanismo antinflamatorio de los VDRAs mediante la modulación de la vía del EGFR y de la ruta no canónica de NF-κB. En resumen, estos datos sugieren que la vía de señalización de EGFR podría ser considerada como una nueva diana terapéutica en el daño renal debido a su participación recurrente en el proceso inflamatorio y fibrótico en respuesta a diferentes estímulos en el riñón. El uso de bloqueantes de esta vía de señalización podría tener un alto valor terapéutico para el tratamiento de pacientes con ECR.Chronic kidney diseases (CKD) are characterized by persistent inflammation and progressive fibrosis leading to end stage renal disease. Several studies have demonstrated that CCN2, PTHrP and TWEAK, are key factors involved in the progression of CKD. EGFR is a membrane tyrosine kinase receptor expressed in the kidney. Previous data have described the role of EGFR in experimental renal fibrosis, but information about its potential role in the inflammatory process is scarce. The main aim of this thesis was to investigate the contribution of the EGFR pathway in experimental kidney damage, evaluating its role on inflammation and fibrosis, and the intracellular mechanisms involved in EGFR signalling. An additional goal was to increase the actual knowledge of renal pathology and improve the current therapeutic strategies. EGFR activation may occur by direct binding or by "transactivation", the latter process mediated by MMPs/ADAMs. The results of this study have shown that CCN2 is a new EGFR ligand that directly binds to this receptor and activates its signalling pathway, by an MMPs/ADAMs independent process. Furthermore, EGFR can be transactivated in the kidney by several factors involved in renal damage such as PTHrP and TWEAK, as described here for the first time. PTHrP, by its binding to the G coupled receptor PTH1R, can transactivate EGFR by 2 different mechanisms; PKC/MMPs activation or Src activation. TWEAK, through interaction with its receptor Fn14, activates ADAM17 that release HB-EGF and TGF-α ligands, leading to EGFR transactivation. Previous experimental studies suggest that EGFR pathway blockade could be an antifibrotic target for renal disease. In vitro studies showed that direct activation of EGFR by CCN2, and EGFR transactivation by PTHrP, could regulate epithelial mesenchymal transition, a process that contributes to renal fibrogenesis. In vivo studies, including the experimental models of renal damage mediated caused by systemic administration of CCN2 (IV) or TWEAK in mice, have demonstrated that activation of the EGFR pathway is associated with an inflammatory process in the kidney, which it is prevented by EGFR pharmacological blockade. In particular, TWEAK-induced EGFR transactivation and renal inflammation was blocked by ADAM17/EGFR inhibition, suggesting that the blockade of this axis could be a good therapeutic option for renal inflammatory diseases. Chronic renal disease is characterized by vitamin D deficiency. Several experimental data have shown that vitamin D receptor agonists (VDRAs) exert beneficial antinflammatory effects in CKD. In this thesis we have described that treatment with the VDRA Paricalcitol inhibited TWEAK-mediated EGFR transactivation and subsequent activation of intracellular mechanisms, including overexpression of proinflammatory factors and the infiltration of inflammatory cells into the kidney. The NF-κB plays a key role in the regulation of the inflammatory response. TWEAK is one of the few cytokines that activates both the canonical and non-canonical NF-κB pathway. Blockade of TWEAK-induced EGFR transactivation by different approaches, including Paricalcitol, inhibited the non canonical, but not the canonical, NF-κB pathway. These results described a novel antinflammatory mechanism of VDRAs that includes the modulation of the EGFR pathway and the inhibition of the noncanonical NF-κB2 pathway. In summary, all these data show that EGFR signalling pathway activation is involved in the modulation of inflammatory and fibrotic process in the kidney in response to different stimuli, and suggest that the blockade of EGFR signalling pathway could be considered as a new therapeutic target in renal diseases. Blockers of this signalling pathway could have a relevant therapeutic value for the treatment of CKD patients

Special issue “Diabetic nephropathy: Diagnosis, prevention and treatment”

Diabetic nephropathy (DN) is the main cause of end-stage renal disease. DN is a complex disease mediated by genetic and environmental factors, and many cellular and molecular mechanisms are involved in renal damage in diabetes. There are no biomarkers that reflect the severity of the underlying renal histopathological changes and can e ectively predict the progression of renal damage and stratify the risk of DN among individuals with diabetes mellitus. Current therapeutic strategies are based on the strict control of glucose and blood pressure levels and, although there are new anti-diabetic drugs, these treatments only retard renal damage progression, being necessary novel therapies. In this Special Issue, there are several comprehensive reviews and interesting original papers covering all these topics, which would be of interest to the growing number of readers of the Journal of Clinical MedicineEditors are funding by Grants from the Instituto de Salud Carlos III(ISCIII) and Fondos FEDER European Union (PI17/00119 and Red de Investigación Renal (REDINREN): RD16/0009, to M.R-O), Comunidad de Madrid (“NOVELREN” B2017/BMD-3751 to M.R-O); the José Castillejo grant (CAS19/00133 to R.R.R-D); the “Juan de la Cierva Formacion” training program of the Ministerio de Economia, Industria y Competitividad (MINECO) supported the salary of SR-M (FJCI-2016-29050); Sociedad Española de Nefrologia (S.E.N. to M.R-O). Grants PAI 82140017 to C.L. of Chile; IMPROVE-PD project (“Identification and Management of Patients atRisk–Outcome and Vascular Events in Peritoneal Dialysis”) funding from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie Grant Agreement No. 812699 to M.R.O

Bromodomain and extraterminal proteins as vovel epigenetic targets for renal diseases

Epigenetic mechanisms, especially DNA methylation and histone modifications, are dynamic processes that regulate the gene expression transcriptional program in normal and diseased states. The bromodomain and extraterminal (BET) protein family (BRD2, BRD3, BRD4, and BRDT) are epigenetic readers that, via bromodomains, regulate gene transcription by binding to acetylated lysine residues on histones and master transcriptional factors. Experimental data have demonstrated the involvement of some BET proteins in many pathological conditions, including tumor development, infections, autoimmunity, and inflammation. Selective bromodomain inhibitors are epigenetic drugs that block the interaction between BET proteins and acetylated proteins, thus exerting beneficial effects. Recent data have described the beneficial effect of BET inhibition on experimental renal diseases. Emerging evidence underscores the importance of environmental modifications in the origin of pathological features in chronic kidney diseases (CKD). Several cellular processes such as oxidation, metabolic disorders, cytokines, inflammation, or accumulated uremic toxins may induce epigenetic modifications that regulate key processes involved in renal damage and in other pathological conditions observed in CKD patients. Here, we review how targeting bromodomains in BET proteins may regulate essential processes involved in renal diseases and in associated complications found in CKD patients, such as cardiovascular damage, highlighting the potential of epigenetic therapeutic strategies against BET proteins for CKD treatment and associated risksThis work was supported by grants from the Instituto de Salud Carlos III (ISCIII) and Fondos FEDER European Union (PI17/00119; Red de Investigación Renal REDINREN: RD16/0009 and PI17/01244), Sociedad Española de Nefrología and “NOVELREN-CM: Enfermedad renal crónica: nuevas Estrategias para la prevención, Diagnóstico y tratamiento”; B2017/BMD- 3751, Comunidad de Madrid. The “Juan de la Cierva Formacion” training program of the Ministerio de Economia, Industria y Competitividad supported the salary of SR-M (FJCI-2016-29050

Role of Epidermal Growth Factor Receptor (EGFR) and Its Ligands in Kidney Inflammation and Damage

Chronickidneydisease (CKD)ischaracterized bypersistent inflammationandprogressive fibrosis,ultimatelyleadingto end-stage renal disease. Although many studies have investigated the factors involved in the progressive deterioration of renal function, current therapeutic strategies only delay disease progression, leaving an unmet need for effective therapeutic interventions that target the cause behind the inflammatory process and could slow down or reverse the development and progression of CKD. Epidermal growth factor receptor (EGFR) (ERBB1), a membrane tyrosine kinase receptor expressed in the kidney, is activated after renal damage, and preclinical studies have evidenced its potential as a therapeutic target in CKD therapy. To date, seven official EGFR ligands have been described, including epidermal growth factor (EGF) (canonical ligand), transforming growth factor-α, heparin-binding epidermal growth factor, amphiregulin, betacellulin, epiregulin, and epigen. Recently, the connective tissue growth factor (CTGF/CCN2) has been described as a novel EGFR ligand. The direct activation of EGFR by its ligands can exert different cellular responses, depending on the specific ligand, tissue, and pathological condition. Among all EGFR ligands, CTGF/CCN2 is of special relevance in CKD. This growth factor, by binding to EGFR and downstream signaling pathway activation, regulates renal inflammation, cell growth, and fibrosis. EGFR can also be “transactivated” by extracellular stimuli, including several key factors involved in renal disease, such as angiotensin II, transforming growth factor beta (TGFB), and other cytokines, including members of the tumor necrosis factor superfamily, showing another important mechanism involved in renal pathology. The aim of this review is to summarize the contribution of EGFR pathway activation in experimental kidney damage, with special attention to the regulation of the inflammatory response and the role of some EGFR ligands in this process. Better insights in EGFR signaling in renal disease could improve our current knowledge of renal pathology contributing to therapeutic strategies for CKD development and progression.This work was supported by the Instituto de Salud Carlos III and Fondos FEDER European Union (PI014/00041, PI17/00119), Red de Investigación Renal (REDinREN; RD16/0009), Comunidad de Madrid (B2017/BMD-3751 NOVELREN-CM), and Sociedad Española de Nefrología. The “Juan de la Cierva de Formacion” training program of the Ministerio de Economía, Industria y Competitividad, Gobierno de España supported the salary of SR-M (FJCI-2016-29050)

Non-coding rnas in kidney diseases: The long and short of them

Recent progress in genomic research has highlighted the genome to be much more transcribed than expected. The formerly so-called junk DNA encodes a miscellaneous group of largely unknown RNA transcripts, which contain the long non-coding RNAs (lncRNAs) family. lncRNAs are instrumental in gene regulation. Moreover, understanding their biological roles in the physiopathology of many diseases, including renal, is a new challenge. lncRNAs regulate the effects of microRNAs (miRNA) on mRNA expression. Understanding the complex crosstalk between lncRNA– miRNA–mRNA is one of the main challenges of modern molecular biology. This review aims to summarize the role of lncRNA on kidney diseases, the molecular mechanisms involved, and their function as emerging prognostic biomarkers for both acute and chronic kidney diseases. Finally, we will also outline new therapeutic opportunities to diminish renal injury by targeting lncRNA with antisense oligonucleotides.This research was funded by SFNDT, Vifor. (L.M., V.M.-L.M. and E.H.), Instituto de Salud Carlos III (ISCIII, FIS-FEDER PI17/00130 and PI20/00375), Spanish Biomedical Research Centre in Cardiovascular Diseases (CIBERCV), Spanish Ministry of Science and Innovation (RYC-2017-22369), and Spanish Society of Nephrology (SEN). The “PFIS” and “Sara Borrell” training program of the ISCIII supported the salary of MGH (FI18/00310) and SR-M (CD19/00021). Córdoba University supported the salary of C.G.C

Gremlin regulates tubular epithelial to mesenchymal transition via VEGFR2: Potential role in renal fibrosis

Chronic kidney disease (CKD) is emerging as an important health problem due to the increase number of CKD patients and the absence of an effective curative treatment. Gremlin has been proposed as a novel therapeutic target for renal inflammatory diseases, acting via Vascular Endothelial Growth Factor Receptor-2 (VEGFR2). Although many evidences suggest that Gremlin could regulate renal fibrosis, the receptor involved has not been yet clarified. Gremlin, as other TGF-β superfamily members, regulates tubular epithelial to mesenchymal transition (EMT) and, therefore, could contribute to renal fibrosis. In cultured tubular epithelial cells Gremlin binding to VEGFR2 is linked to proinflammatory responses. Now, we have found out that in these cells VEGFR2 is also involved in the profibrotic actions of Gremlin. VEGFR2 blockade by a pharmacological kinase inhibitor or gene silencing diminished Gremlin-mediated gene upregulation of profibrotic factors and restored changes in EMT-related genes. Moreover, VEGFR2 inhibition blocked EMT phenotypic changes and dampened the rate of wound healing in response to Gremlin. The role of VEGFR2 in experimental fibrosis was evaluated in experimental unilateral ureteral obstruction. VEFGR2 inhibition diminished the upregulation of profibrotic genes and EMT changes, as well as the accumulation of extracellular matrix proteins, such as fibronectin and collagens in the obstructed kidneys. Notch pathway activation participates in renal damage progression by regulating cell growth/proliferation, regeneration and inflammation. In cultured tubular epithelial cells, Notch inhibition markedly downregulated Gremlin-induced EMT changes and wound healing speed. These results show that Gremlin regulates the EMT process via VEGFR2 and Notch pathway activation, suggesting that the Gremlin/VEGFR2 axis could be a potential therapeutic target for CKD.This work was supported by grants from the Instituto de Salud Carlos III (ISCIII) and Fondos FEDER European Union (PI16/02057, PI17/00119, PI17/01495, and Red de Investigación Renal REDINREN: RD16/0009), Sociedad Española de Nefrologia, “NOVELREN-CM: Enfermedad renal crónica: nuevas Estrategias para la prevención, Diagnóstico y tratamiento”; B2017/BMD-3751, B2017/BMD-3686 CIFRA2-CM, PAI 82140017, and FONDECYT 1160465 (Chile) and Bayer HealthCare AG (Grants4Targets initiative, Berlin, Germany)

Epigenetic Modification Mechanisms Involved in Inflammation and Fibrosis in Renal Pathology

The growing incidence of obesity, hypertension, and diabetes, coupled with the aging of the population, is increasing the prevalence of renal diseases in our society. Chronic kidney disease (CKD) is characterized by persistent inflammation, fibrosis, and loss of renal function leading to end-stage renal disease. Nowadays, CKD treatment has limited effectiveness underscoring the importance of the development of innovative therapeutic options. Recent studies have identified how epigenetic modifications participate in the susceptibility to CKD and have explained how the environment interacts with the renal cell epigenome to contribute to renal damage. Epigenetic mechanisms regulate critical processes involved in gene regulation and downstream cellular responses. The most relevant epigenetic modifications that play a critical role in renal damage include DNA methylation, histone modifications, and changes in miRNA levels. Importantly, these epigenetic modifications are reversible and, therefore, a source of potential therapeutic targets. Here, we will explain how epigenetic mechanisms may regulate essential processes involved in renal pathology and highlight some possible epigenetic therapeutic strategies for CKD treatment.This work was supported by Instituto de Salud Carlos III and Fondos FEDER European Union (PI14/00041, PI15/00960, PI16/01354, PI17/00119, and PI17/01244), Red de Investigación Renal (REDinREN; RD16/0009), Comunidad de Madrid (B2017/BMD-3751 NOVELREN-CM), Fondecyt 1181574 (BK), Sociedad Española de Nefrología, and the “Juan de la Cierva Formacion” training program of the Ministerio de Economia, Industria y Competitividad which supported the salary of S.R-M (FJCI-2016-29050). V. Marchant has a CONICYT Scholarship for his graduate studies at the PhD program in Medical Science, Universidad Austral de Chile. The Centro de Estudios Científicos is funded by the Chilean Government through the Centers of Excellence Basal Financing Program of CONICYT

Statins Inhibit Angiotensin II/Smad Pathway and Related Vascular Fibrosis, by a TGF-β-Independent Process

We have recently described that in an experimental model of atherosclerosis and in vascular smooth muscle cells (VSMCs) statins increased the activation of the Smad pathway by transforming growth factor-β (TGF-β), leading to an increase in TGF-β-dependent matrix accumulation and plaque stabilization. Angiotensin II (AngII) activates the Smad pathway and contributes to vascular fibrosis, although the in vivo contribution of TGF-β has not been completely elucidated. Our aim was to further investigate the mechanisms involved in AngII-induced Smad activation in the vasculature, and to clarify the beneficial effects of statins on AngII-induced vascular fibrosis. Infusion of AngII into rats for 3 days activates the Smad pathway and increases fibrotic-related factors, independently of TGF-β, in rat aorta. Treatment with atorvastatin or simvastatin inhibited AngII-induced Smad activation and related-fibrosis. In cultured rat VSMCs, direct AngII/Smad pathway activation was mediated by p38 MAPK and ROCK activation. Preincubation of VSMCs with statins inhibited AngII-induced Smad activation at all time points studied (from 20 minutes to 24 hours). All these data show that statins inhibited several AngII-activated intracellular signaling systems, including p38-MAPK and ROCK, which regulates the AngII/Smad pathway and related profibrotic factors and matrix proteins, independently of TGF-β responses. The inhibitory effect of statins on the AngII/Smad pathway could explain, at least in part, their beneficial effects on hypertension-induced vascular damage

CCN2 Binds to Tubular Epithelial Cells in the Kidney

Cellular communication network-2 (CCN2), also called connective tissue growth factor (CTGF), is considered a fibrotic biomarker and has been suggested as a potential therapeutic target for kidney pathologies. CCN2 is a matricellular protein with four distinct structural modules that can exert a dual function as a matricellular protein and as a growth factor. Previous experiments using surface plasmon resonance and cultured renal cells have demonstrated that the C-terminal module of CCN2 (CCN2(IV)) interacts with the epidermal growth factor receptor (EGFR). Moreover, CCN2(IV) activates proinflammatory and profibrotic responses in the mouse kidney. The aim of this paper was to locate the in vivo cellular CCN2/EGFR binding sites in the kidney. To this aim, the C-terminal module CCN2(IV) was labeled with a fluorophore (Cy5), and two different administration routes were employed. Both intraperitoneal and direct intra-renal injection of Cy5-CCN2(IV) in mice demonstrated that CCN2(IV) preferentially binds to the tubular epithelial cells, while no signal was detected in glomeruli. Moreover, co-localization of Cy5-CCN2(IV) binding and activated EGFR was found in tubules. In cultured tubular epithelial cells, live-cell confocal microscopy experiments showed that EGFR gene silencing blocked Cy5-CCN2(IV) binding to tubuloepithelial cells. These data clearly show the existence of CCN2/EGFR binding sites in the kidney, mainly in tubular epithelial cells. In conclusion, these studies show that circulating CCN2(IV) can directly bind and activate tubular cells, supporting the role of CCN2 as a growth factor involved in kidney damage progression