Histone lysine crotonylation during acute kidney injury in mice

Acute kidney injury (AKI) is a potentially lethal condition for which no therapy is available beyond replacement of renal function. Posttranslational histone modifications modulate gene expression and kidney injury. Histone crotonylation is a recently described posttranslational modification. We hypothesized that histone crotonylation might modulate kidney injury. Histone crotonylation was studied in cultured murine proximal tubular cells and in kidneys from mice with AKI induced by folic acid or cisplatin. Histone lysine crotonylation was observedintubularcells from healthy murine and human kidney tissue. Kidney tissue histone crotonylation increased during AKI. This was reproducedbyexposure tothe protein TWEAK incultured tubular cells. Specifically, ChIP-seq revealed enrichment of histone crotonylation at the genes encoding the mitochondrial biogenesis regulator PGC-1α and the sirtuin-3 decrotonylase in both TWEAK-stimulated tubular cells and in AKI kidney tissue. To assess the role of crotonylation in kidney injury, crotonate was used to increase histone crotonylation in cultured tubular cells or in the kidneys in vivo. Crotonate increased the expression of PGC-1α and sirtuin-3, and decreased CCL2 expression in cultured tubular cells and healthy kidneys. Systemic crotonate administration protected from experimental AKI, preventing the decrease in renal function and in kidney PGC-1α and sirtuin-3 levels as well as the increase in CCL2 expression. For the first time, we have identified factors such as cell stress and crotonate availability that increase histone crotonylation in vivo. Overall, increasing histone crotonylation might have a beneficial effect on AKI. This is the first observation of the in vivo potential of the therapeutic manipulation of histone crotonylation in a disease state.This work was supported by the Instituto de Salud Carlos III (ISCIII) [grant numbers PI13/00047, PIE13/00051, PI14/00386, PI15/00298, CP12/03262, CP14/00133, RETIC REDinREN RD12/0021]; the European Regional Development Funds [Fondo Europeo de DesarrolloRegional (FEDER)]; European Uremic Toxin (EUTox) Work Group of the ESAO; the Sociedad Española de Nefrologia (SEN) [9749/002]; Comunidad de Madrid (CIFRA) [grant number S2010/BMD-2378]; and Fundación Renal Iñigo Álvarez de Toledo (FRIAT) [9749/001]. Salary support was provided by ISCIII Miguel Servet MS12/03262 and MS14/00133 to A.B.S. and M.D.S.-N., MECD to O.R.-A. and programa Intensificación Actividad Investigadora (ISCIII/Agencia Laı́n-Entralgo/CM) to A.O. IIS-FJD Biobank RD09/0076/0010

Glomerulonefritis rápidamente progresiva asociada a endocarditis afebril y anca anti-proteinasa 3

Endocarditis associated with antiPR3 ANCA and acute kidney injure generates a challenge in its diagnosis and treatment. In order to make a review about that combination, we presented a patient with necrotizing glomerulonephritis produced by a Enterococcus faecalis´s subacute endocarditis and antiPR3 ANCA positive.Differential diagnosis is made between an acute kidney failure produced by ANCA´s vasculitis vs necrotizing glomerulonephritis by endocarditis. Frequently it is necessary to make a biopsy to get a diagnosis. Negative immunofluorescence will guide to vasculitis associated ANCA, while positive immune complexes will guide to poststreptococcal glomerulonephritis.Other challenge that generates the association of acute kidney disease, endocarditis and antiPR3 ANCA is the treatment. ANCA positive can prompt to start immunosuppressant treatments. However, in the context of endocarditis, it could be inadvisable and even dangerous to use it. For this reason, it is controversial the use of immunosuppressant in combination with antibiotics in the acute process, in contrast with the use of only antibiotics. In the current paper we collect the 19 reports in the literature about endocarditis associated with antiPR3 ANCA, the treatment and the renal evolution of each patient. We concluded, generally, a better improvement of kidney function in patients treated with only antibiotics than those patients treated with the combination of  antibiotics and corticoids. However, there are so few reports that we can´t consider significant the different between both treatment groups.La endocarditis asociada a ANCA anti-PR3 e insuficiencia renal plantea un dilema tanto en su diagnóstico como tratamiento. Para abordar una revisión de dicho tema, se presenta el caso de un paciente con glomerulonefritis rápidamente progresiva secundaria a endocarditis subaguda por Enterococcus faecalis y positividad para ANCA anti-PR3. El diagnóstico diferencial principal se establecería entre una afectación renal de una vasculitis asociada a ANCA no diagnosticada previamente vs una glomerulonefritis postinfecciosa secundaria a la endocarditis. En muchos casos es necesario disponer de una biopsia renal que esclarezca el diagnóstico, ya que una inmunofluorescencia negativa orientará hacia una vasculitis, mientras que una positividad para inmunocomplejos iría a favor de una glomerulonefritis postestreptocócica. El tratamiento a seguir es otro reto que se plantea en la coexistencia de insuficiencia renal aguda, endocarditis y ANCA anti-PR3 positivo. La positividad de ANCAs induce a valorar iniciar tratamiento con inmunosupresores, no obstante, en el lecho de una endocarditis puede resultar desaconsejado e incluso poner en riesgo la vida del paciente someterlo a un estado de inmunosupresión. Es, por tanto, controvertido el uso de inmunosupresión en combinación con antibioterapia en el proceso agudo en contraposición al uso de antibioterapia exclusivamente. En el actual artículo se recogen los 19 casos publicados en la literatura de endocarditis asociados a ANCA anti-PR3, así como el tratamiento que se realizó en cada uno de los casos y la evolución en la función renal de cada paciente, concluyendo, en general, una mejor recuperación de la función renal en los pacientes tratados con antibioterapia en exclusiva que en aquellos tratados con la combinación antibióticocorticoides. Sin embargo, dado el pequeño tamaño muestral, no se puede considerar significativa la diferencia entre ambos tratamientos

Small vessel microembolization and acute glomerulonephritis following infection of aesthetic filler implants

Background: The systemic consequences of esthetic filler injections are poorly understood. Case presentation: We report a patient with a past history of subcutaneous injection of aesthetic filler material in the lower legs, who presented with post-infectious glomerulonephritis following necrotic leg ulcers at the injection site. Kidney biopsy revealed the presence of translucent, non-birefringent microspherical bodies compatible with polymethylmetacrylate (PMMA) microspheres in some capillary lumens. This had not previously been described. PMMA is a biphasic aesthetical filler composed of polymethylmetacrylate microspheres suspended in a biodegradable bovine collagen carrier. The solid phase (PMMA microspheres) persists in tissues for years. Although PMMA was thought to not disseminate systemically, tissue necrosis may have favored systemic dissemination of the microspheres, although entry in the circulation and microembolization at the time of administration cannot be ruled out. Conclusions: In conclusion, aesthetic filler implants may cause microembolization into small vessels. Recognition of the characteristic morphology may expedite diagnosis and avoid unnecessary further testing.AO and CMC were supported by ISCIII and FEDER funds PI13/00047, REDinREN RD012/0021, Comunidad de Madrid CIFRA S2010/BMD-2378 and Programa Intensificación Actividad Investigadora. BFF by ISCIII Joan Rodes

Albumin-induced apoptosis of tubular cells is modulated by BASP1

Albuminuria promotes tubular injury and cell death, and is associated with faster progression of chronic kidney disease (CKD) to end-stage renal disease. However, the molecular mechanisms regulating tubular cell death in response to albuminuria are not fully understood. Brain abundant signal protein 1 (BASP1) was recently shown to mediate glucose-induced apoptosis in tubular cells. We have studied the role of BASP1 in albumin-induced tubular cell death. BASP1 expression was studied in experimental puromycin aminonucleoside-induced nephrotic syndrome in rats and in human nephrotic syndrome. The role of BASP1 in albumin-induced apoptosis was studied in cultured human HK2 proximal tubular epithelial cells. Puromycin aminonucleoside induced proteinuria and increased total kidney BASP1 mRNA and protein expression. Immunohistochemistry localized the increased BASP1 to tubular cells. BASP1 expression colocalized with deoxynucleotidyl-transferase-mediated dUTP nick-end labeling staining for apoptotic cells. Increased tubular BASP1 expression was observed in human proteinuric nephropathy by immunohistochemistry, providing evidence for potential clinical relevance. In cultured tubular cells, albumin induced apoptosis and increased BASP1 mRNA and protein expression at 6–48 h. Confocal microscopy localized the increased BASP1 expression in albumin-treated cells mainly to the perinuclear area. A peripheral location near the cell membrane was more conspicuous in albumin-treated apoptotic cells, where it colocalized with actin. Inhibition of BASP1 expression by a BASP1 siRNA protected from albumin-induced apoptosis. In conclusion, albumin-induced apoptosis in tubular cells is BASP1-dependent. This information may be used to design novel therapeutic approaches to slow CKD progression based on protection of tubular cells from the adverse consequences of albuminuriaGrant support: FIS PS09/00447, PI13/00047, CP14/ 00133, ISCIII-RETIC, REDinREN/RD06/0016/and RD012/0021 FEDER funds, Comunidad de Madrid/CIFRA S2010/BMD-2378. Salary support: FIS to MDSN and ABS (Miguel Servet), Beatriz Fernandez-Fernandez (Rio Hortega). Programa Intensificación Actividad Investigadora (ISCIII/Agencia Laín-Entralgo/CM) to AO. IIS-FJD Biobank RD09/0076/0010

Podocyte and tubular involvement in AngioJet-induced kidney injury

Altres ajuts: Sociedad Española de Nefrología, Fundacion Renal Iñigo Álvarez de Toledo and Comunidad de Madrid CIFRA2 B2017/BMD-3686.The AngioJet technique combines localized thrombolysis and percutaneous mechanical thrombectomy (PMT). However, PMT may cause acute kidney injury (AKI), which has been ascribed to severe mechanical haemolysis, although no renal biopsies have been reported. We now report the first renal biopsy in a patient with AKI following PMT. There is histological evidence of haemoglobin (Hb)-induced tubular injury and podocyte stress characterized by intracellular Hb and staining for ferritin and hemo-oxygenase-1, suggestive of an adaptive response to oxidative stress. This confirms that Hb is involved in kidney cell injury and supports the existence of several different kidney cellular targets

Effective nephroprotection against acute kidney injury with a star-shaped polyglutamate-curcuminoid conjugate

The lack of efective pharmacological treatments for acute kidney injury (AKI) remains a signifcant public health problem. Given the involvement of apoptosis and regulated necrosis in the initiation and progression of AKI, the inhibition of cell death may contribute to AKI prevention/recovery. Curcuminoids are a family of plant polyphenols that exhibit attractive biological properties that make them potentially suitable for AKI treatment. Now, in cultured tubular cells, we demonstrated that a crosslinked self-assembled star-shaped polyglutamate (PGA) conjugate of bisdemethoxycurcumin (StPGA-CL-BDMC) inhibits apoptosis and necroptosis induced by Tweak/TNFα/IFNγ alone or concomitant to caspase inhibition. St-PGA-CL-BDMC also reduced NF-κB activation and subsequent gene transcription. In vivo, St-PGA-CL-BDMC prevented renal cell loss and preserved renal function in mice with folic acid-induced AKI. Mechanistically, St-PGA-CL-BDMC inhibited AKI-induced apoptosis and expression of ferroptosis markers and also decreased the kidney expression of genes involved in tubular damage and infammation, while preserving the kidney expression of the protective factor, Klotho. Thus, due to renal accumulation and attractive pharmacological properties, the application of PGAbased therapeutics may improve nephroprotective properties of current AKI treatmentsTis work was supported by grants from the Instituto de Salud Carlos III, FEDER funds: PI16/02057, PI16/01900, PI18/01133, PI19/00815, ISCIII RETIC REDINREN RD16/0009; Sociedad Española de Nefrología; FRIAT; Comunidad de Madrid en Biomedicina B2017/BMD-3686 CIFRA2-CM; ERA-PerMed-JTC2018 (AC18/00071; DTS18/00032); Spanish Ministry of Economy and Competitiveness (Grant numbers SAF2013-44848-R, SAF2016-80427-R). Partly co-funded by FEDER (PO FEDER Valencian Community - 2014–2020

Nrf2 Plays a Protective Role Against Intravascular Hemolysis-Mediated Acute Kidney Injury

Massive intravascular hemolysis is associated with acute kidney injury (AKI). Nuclear factor erythroid-2-related factor 2 (Nrf2) plays a central role in the defense against oxidative stress by activating the expression of antioxidant proteins. We investigated the role of Nrf2 in intravascular hemolysis and whether Nrf2 activation protected against hemoglobin (Hb)/heme-mediated renal damage in vivo and in vitro. We observed renal Nrf2 activation in human hemolysis and in an experimental model of intravascular hemolysis promoted by phenylhydrazine intraperitoneal injection. In wild-type mice, Hb/heme released from intravascular hemolysis promoted AKI, resulting in decreased renal function, enhanced expression of tubular injury markers (KIM-1 and NGAL), oxidative and endoplasmic reticulum stress (ER), and cell death. These features were more severe in Nrf2-deficient mice, which showed decreased expression of Nrf2-related antioxidant enzymes, including heme oxygenase 1 (HO-1) and ferritin. Nrf2 activation with sulforaphane protected against Hb toxicity in mice and cultured tubular epithelial cells, ameliorating renal function and kidney injury and reducing cell stress and death. Nrf2 genotype or sulforaphane treatment did not influence the severity of hemolysis. In conclusion, our study identifies Nrf2 as a key molecule involved in protection against renal damage associated with hemolysis and opens novel therapeutic approaches to prevent renal damage in patients with severe hemolytic crisis. These findings provide new insights into novel aspects of Hb-mediated renal toxicity and may have important therapeutic implications for intravascular hemolysis-related diseases.Supported by FIS/FEDER CP14/00008, CP16/00014, CP16/00017, PI15/00448, PI16/00735, PI16/02057, PI17/00130, PI17/01495, PI17/01700, ISCIII-RETIC REDinREN RD012/0021, RD016/0009 FEDER funds, Spanish Ministry of Economy and Competitiveness (RYC-2017-22369), Sociedad Española de Nefrología, Fundacion Renal Iñigo Álvarez de Toledo (FRIAT), Comunidad de Madrid CIFRA2 B2017/BMD-3686 and BMD-3827, Fundacion La Caixa, CaixaImpulse program CI17-00048, and Spanish Biomedical Research Centre in Diabetes and Associated Metabolic Disorders (CIBERDEM).S

Association of kidney fibrosis with urinary peptides: a path towards non-invasive liquid biopsies?

Chronic kidney disease (CKD) is a prevalent cause of morbidity and mortality worldwide. A hallmark of CKD progression is renal fibrosis characterized by excessive accumulation of extracellular matrix (ECM) proteins. In this study, we aimed to investigate the correlation of the urinary proteome classifier CKD273 and individual urinary peptides with the degree of fibrosis. In total, 42 kidney biopsies and urine samples were examined. The percentage of fibrosis per total tissue area was assessed in Masson trichrome stained kidney tissues. The urinary proteome was analysed by capillary electrophoresis coupled to mass spectrometry. CKD273 displayed a significant and positive correlation with the degree of fibrosis (Rho = 0.430, P = 0.0044), while the routinely used parameters (glomerular filtration rate, urine albumin-to-creatinine ratio and urine protein-to-creatinine ratio) did not (Rho = -0.222; -0.137; -0.070 and P = 0.16; 0.39; 0.66, respectively). We identified seven fibrosis-associated peptides displaying a significant and negative correlation with the degree of fibrosis. All peptides were collagen fragments, suggesting that these may be causally related to the observed accumulation of ECM in the kidneys. CKD273 and specific peptides are significantly associated with kidney fibrosis; such an association could not be detected by other biomarkers for CKD. These non-invasive fibrosis-related biomarkers can potentially be implemented in future trials

Osteoprotegerin in Exosome-Like Vesicles from Human Cultured Tubular Cells and Urine

Urinary exosomes have been proposed as potential diagnostic tools. TNF superfamily cytokines and receptors may be present in exosomes and are expressed by proximal tubular cells. We have now studied the expression of selected TNF superfamily proteins in exosome-like vesicles from cultured human proximal tubular cells and human urine and have identified additional proteins in these vesicles by LC-MS/MS proteomics. Human proximal tubular cells constitutively released exosome-like vesicles that did not contain the TNF superfamily cytokines TRAIL or TWEAK. However, exosome-like vesicles contained osteoprotegerin (OPG), a TNF receptor superfamily protein, as assessed by Western blot, ELISA or selected reaction monitoring by nLC-(QQQ)MS/MS. Twenty-one additional proteins were identified in tubular cell exosomelike vesicles, including one (vitamin D binding protein) that had not been previously reported in exosome-like vesicles. Twelve were extracellular matrix proteins, including the basement membrane proteins type IV collagen, nidogen-1, agrin and fibulin-1. Urine from chronic kidney disease patients contained a higher amount of exosomal protein and exosomal OPG than urine from healthy volunteers. Specifically OPG was increased in autosomal dominant polycystic kidney disease urinary exosome-like vesicles and expressed by cystic epithelium in vivo. In conclusion, OPG is present in exosome-like vesicles secreted by proximal tubular epithelial cells and isolated from Chronic Kidney Disease urine.This work was supported by grants from the Instituto de Salud Carlos III (ISCIIIRETIC REDINREN RD06/0016, RD12/0021, PI11/01854, PI10/00072 PI09/ 00641 and PS09/00447); Comunidad de Madrid (Fibroteam S2010/BMD-2321, S2010/BMD-2378); Sociedad Española de NefrologÍa; European Network (HEALTH F2-2008-200647); DIALOK European project LSHB-CT-2007-036644; Fundacion Lilly and IRSIN/FRIAT to JE; Programa Intensificación Actividad Investigadora (ISCIII/ Agencia Laín-Entralgo/CM) to AO; Instituto de Salud Carlos III (FIS PI11/01401, CP09/00229); and Fundación Conchita Rábago de Jiménez DÍaz to GAL. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscrip

Positive/retained SDHB immunostaining in renal cell carcinomas associated to germline SDHB-deficiency: case report.

According to WHO, succinate dehydrogenase (SDH)-deficient renal cell carcinoma is characterized by negative immunostaining for SDHB, which remains positive in non-tumor tissue despite germline mutations in the SDHB gene. We now report a patient with a SDHB mutation, c.166_170del (p.Pro56Tyrfs*5) who developed renal cell carcinomas with characteristic morphological features of SDH-deficient renal cell carcinoma but had positive SDHB immunostaining. Within a 6-year period, the patient developed two different renal cell carcinomas, which had characteristic morphological features of SDH-deficient renal cell carcinoma (uniform cells characteristically displaying eosinophilic granular material intermixed with fewer cells exhibiting clear intracytoplasmic inclusions and bland centered nuclei) but displayed immunohistochemistry for SDHB with a cytoplasmic granular positivity (mitochondrial pattern) in tumor cells. For the second case, this was initially interpreted as positive by IHC, but on review some subtle differences were identified. SDHB immunostaining may be positive in renal cell carcinoma associated to germline SDHB deficiency which have other typical morphological features. Immunohistochemistry interpretation may be complex