The role of PGC-1α and mitochondrial biogenesis in kidney diseases

Chronic kidney disease (CKD) is one of the fastest growing causes of death worldwide, emphasizing the need to develop novel therapeutic approaches. CKD predisposes to acute kidney injury (AKI) and AKI favors CKD progression. Mitochondrial derangements are common features of both AKI and CKD and mitochondria-targeting therapies are under study as nephroprotective agents. PGC-1α is a master regulator of mitochondrial biogenesis and an attractive therapeutic target. Low PGC-1α levels and decreased transcription of its gene targets have been observed in both preclinical AKI (nephrotoxic, endotoxemia, and ischemia-reperfusion) and in experimental and human CKD, most notably diabetic nephropathy. In mice, PGC-1α deficiency was associated with subclinical CKD and predisposition to AKI while PGC-1α overexpression in tubular cells protected from AKI of diverse causes. Several therapeutic strategies may increase kidney PGC-1α activity and have been successfully tested in animal models. These include AMP-activated protein kinase (AMPK) activators, phosphodiesterase (PDE) inhibitors, and anti-TWEAK antibodies. In conclusion, low PGC-1α activity appears to be a common feature of AKI and CKD and recent characterization of nephroprotective approaches that increase PGC-1α activity may pave the way for nephroprotective strategies potentially effective in both AKI and CKD.Supported by ISCIII-FIS, FEDER funds, CP14/00133, PI16/02057, PI16/01900, PI18/01366, PI19/00588, PI19/00815, DTS18/00032, ERA-PerMed-JTC2018 (KIDNEY ATTACK AC18/00064 and PERSTIGAN AC18/00071, ISCIII-RETIC REDinREN RD016/0009, Sociedad Española de Nefrología, Fundacion Renal Iñigo Álvarez de Toledo (FRIAT), ISCIII Miguel Servet (A.B.S., M.D.S.-N.), ISCIII Sara Borrell (J.M.M.-M.), Comunidad de Madrid CIFRA2 B2017/BMD-3686 (M.F.-B. and D.M.-S.

Protective role of renal proximal tubular alpha-synuclein in the pathogenesis of kidney fibrosis

Kidney fibrosis is a highly deleterious process and a final manifestation of chronic kidney disease. Alpha-(α)-synuclein (SNCA) is an actin-binding neuronal protein with various functions within the brain; however, its role in other tissues is unknown. Here, we describe the expression of SNCA in renal epithelial cells and demonstrate its decrease in renal tubules of murine and human fibrotic kidneys, as well as its downregulation in renal proximal tubular epithelial cells (RPTECs) after TGF-β1 treatment. shRNA-mediated knockdown of SNCA in RPTECs results in de novo expression of vimentin and α-SMA, while SNCA overexpression represses TGF-β1-induced mesenchymal markers. Conditional gene silencing of SNCA in RPTECs leads to an exacerbated tubulointerstitial fibrosis (TIF) in two unrelated in vivo fibrotic models, which is associated with an increased activation of MAPK-p38 and PI3K-Akt pathways. Our study provides an evidence that disruption of SNCA signaling in RPTECs contributes to the pathogenesis of renal TIF by facilitating partial epithelial-to-mesenchymal transition and extracellular matrix accumulation.This work was supported by research grants PI15/00960 and PI17/00119 from the Instituto de Salud Carlos III (ISCII, Spanish Ministry of Economy and Competitiveness) and REDinREN (RD12/0021). The work on human kidney tissue samples was supported by the IRBLleida Biobank (B.0000682) and PLATAFORMA BIOBANCOS PT17/0015/ 0027. M.B. was supported by the REDinREN (RD12/0021/0026) and Department of Health, Government of Catalonia (PERIS 2016-2020, SLT002/16/00178). M.C. was supported by the studentship from the Catalan Government (AGAUR). R.R.R-D. was supported by a grant from the Comunidad Autonóma de Madrid (B2017/BMD-3751 NOVELREN-CM)

Molecular pathways driving omeprazole nephrotoxicity

Omeprazole, a proton pump inhibitor used to treat peptic ulcer and gastroesophageal reflux disease, has been associated to chronic kidney disease and acute interstitial nephritis. However, whether omeprazole is toxic to renal cells is unknown. Omeprazole has a lethal effect over some cancer cells, and cell death is a key process in kidney disease. Thus, we evaluated the potential lethal effect of omeprazole over tubular cells. Omeprazole induced dose-dependent cell death in human and murine proximal tubular cell lines and in human primary proximal tubular cell cultures. Increased cell death was observed at the high concentrations used in cancer cell studies and also at lower concentrations similar to those in peptic ulcer patient serum. Cell death induced by omeprazole had features of necrosis such as annexin V/7-AAD staining, LDH release, vacuolization and irregular chromatin condensation. Weak activation of caspase-3 was observed but inhibitors of caspases (zVAD), necroptosis (Necrostatin-1) or ferroptosis (Ferrostatin-1) did not prevent omeprazole-induced death. However, omeprazole promoted a strong oxidative stress response affecting mitochondria and lysosomes and the antioxidant N-acetyl-cysteine reduced oxidative stress and cell death. By contrast, iron overload increased cell death. An adaptive increase in the antiapoptotic protein BclxL failed to protect cells. In mice, parenteral omeprazole increased tubular cell death and the expression of NGAL and HO-1, markers of renal injury and oxidative stress, respectively. In conclusion, omeprazole nephrotoxicity may be related to induction of oxidative stress and renal tubular cell deathSupported by FIS CP12/03262, CP14/00133, PI16/02057, PI16/ 01900, PI18/01366, PI19/00588, PI19/00815, DTS18/00032, ERAPerMed-JTC2018 (KIDNEY ATTACK AC18/00064 and PERSTIGAN AC18/00071, ISCIII-RETIC REDinREN RD016/0009 FEDER funds, Sociedad Española de Nefrología, Fundacion Renal Iñigo Álvarez de Toledo (FRIAT), ISCIII Miguel Servet (ABS, MDS-N), ISCIII Sara Borrell (JMM-M), Comunidad de Madrid CIFRA2 B2017/BMD-3686 (MF-B and DM-S

Epigenetic modifiers as potential therapeutic targets in diabetic kidney disease

Diabetic kidney disease is one of the fastest growing causes of death worldwide. Epigenetic regulators control gene expression and are potential therapeutic targets. There is functional interventional evidence for a role of DNA methylation and the histone post-translational modifications—histone methylation, acetylation and crotonylation—in the pathogenesis of kidney disease, including diabetic kidney disease. Readers of epigenetic marks, such as bromodomain and extra terminal (BET) proteins, are also therapeutic targets. Thus, the BD2 selective BET inhibitor apabetalone was the first epigenetic regulator to undergo phase-3 clinical trials in diabetic kidney disease with an endpoint of kidney function. The direct therapeutic modulation of epigenetic features is possible through pharmacological modulators of the specific enzymes involved and through the therapeutic use of the required substrates. Of further interest is the characterization of potential indirect effects of nephroprotective drugs on epigenetic regulation. Thus, SGLT2 inhibitors increase the circulating and tissue levels of β-hydroxybutyrate, a molecule that generates a specific histone modification, β-hydroxybutyrylation, which has been associated with the beneficial health effects of fasting. To what extent this impact on epigenetic regulation may underlie or contribute to the so-far unclear molecular mechanisms of cardio-and nephroprotection offered by SGLT2 inhibitors merits further in-depth studies.This research was funded by FIS/FEDER funds (PI15/00298, CP14/00133, PI16/01900, PI18/01386, PI18/0133, PI19/00588, PI19/00815, DTS18/00032, ERA-PerMed-JTC2018 (KIDNEY ATTACK AC18/00064 and PERSTIGAN AC18/00071), ISCIII-RETIC REDinREN RD016/0009), Sociedad Española de Nefrología, FRIAT, Comunidad de Madrid en Biomedicina B2017/BMD- 3686 CIFRA2-CM. Salary support: ISCIII Miguel Servet to ABS and MDS-N, ISCIII Sara Borrell to JM-MM, REDinREN RD016/0009 to MF-B, and MICIU to JG-M

Cancer outcomes among Parkinson's disease patients with leucine rich repeat kinase 2 mutations, idiopathic Parkinson's disease patients, and nonaffected controls

BACKGROUND: Increased cancer risk has been reported in Parkinson's disease (PD) patients carrying the leucine rich repeat kinase 2 (LRRK2) G2019S mutation (LRRK2-PD) in comparison with idiopathic PD (IPD). It is unclear whether the elevated risk would be maintained when compared with unaffected controls. METHODS: Cancer outcomes were compared among 257 LRRK2-PD patients, 712 IPD patients, and 218 controls recruited from 7 LRRK2 consortium centers using mixed-effects logistic regression. Data were then pooled with a previous study to examine cancer risk between 401 LRRK2-PD and 1946 IPD patients. RESULTS: Although cancer prevalence was similar among LRRK2-PD patients (32.3%), IPD patients (27.5%), and controls (27.5%; P = 0.33), LRRK2-PD had increased risks of leukemia (odds ratio [OR] = 4.55; 95% confidence interval [CI], 1.46-10.61) and skin cancer (OR = 1.61; 95% CI, 1.09-2.37). In the pooled analysis, LRRK2-PD patients had also elevated risks of leukemia (OR = 9.84; 95% CI, 2.15-44.94) and colon cancer (OR = 2.34; 95% CI, 1.15-4.74) when compared with IPD patients. CONCLUSIONS: The increased risks of leukemia as well as skin and colon cancers among LRRK2-PD patients suggest that LRRK2 mutations heighten risks of certain cancers. © 2019 International Parkinson and Movement Disorder Society

Global hyperactivation of enhancers stabilizes human and mouse naïve pluripotency through inhibition of CDK8/19 Mediator kinases

Pluripotent stem cells (PSCs) transition between cell states in vitro and reflect developmental changes in the early embryo. PSCs can be stabilized in the naïve state by blocking extracellular differentiation stimuli, particularly FGF-MEK signaling. Here, we report that multiple features of the naïve state in human and mouse PSCs can be recapitulated without affecting FGF-MEK-signaling or global DNA methylation. Mechanistically, chemical inhibition of CDK8 and CDK19 kinases removes their ability to repress the Mediator complex at enhancers. Thus CDK8/19 inhibition increases Mediator-driven recruitment of RNA Pol II to promoters and enhancers. This efficiently stabilizes the naïve transcriptional program and confers resistance to enhancer perturbation by BRD4 inhibition. Moreover, naïve pluripotency during embryonic development coincides with a reduction in CDK8/19. We conclude that global hyperactivation of enhancers drives naïve pluripotency, and this can be achieved in vitro by inhibiting CDK8/19 kinase activity. These principles may apply to other contexts of cellular plasticity

ADRB2 Arg16Gly Polymorphism, Lung Function, and Mortality: Results from the Atherosclerosis Risk in Communities Study

BACKGROUND: Growing evidence suggests that the Arg16Arg genotype of the beta-2 adrenergic receptor gene may be associated with adverse effects of beta-agonist therapy. We sought to examine the association of beta-agonist use and the Arg16Gly polymorphism with lung function and mortality among participants in the Atherosclerosis Risk in Communities study. METHODOLOGY AND PRINCIPAL FINDINGS: We genotyped study participants and analyzed the association of the Arg16Gly polymorphism and beta-agonist use with lung function at baseline and clinical examination three years later and with all-cause mortality during 10 years of follow-up. Lung function was characterized by percent-predicted forced expiratory volume in 1 second. Associations were examined separately for blacks and whites. Black beta-agonist users with the Arg/Arg genotype had better lung function at baseline and at the second clinical visit than those with Arg/Gly and Gly/Gly genotypes. Adjusted mean percent-predicted FEV(1) was 21% higher in Arg/Arg subjects compared to Gly/Gly at baseline (p = 0.01) and 20% higher than Gly/Gly at visit 2 (p = 0.01). Arg/Gly subjects had adjusted percent-predicted FEV(1) 17% lower than Arg/Arg at baseline but were similar to Arg/Arg subjects at visit 2. Although black beta-agonist users with the Arg/Arg genotype appeared to have better crude survival rates, the association between genotype and all-cause mortality was inconclusive. We found no difference in lung function or mortality by genotype among blacks who did not use beta-agonists or among whites, regardless of beta-agonist use. CONCLUSIONS: Black beta-agonist users with the ADRB2 Arg16Arg genotype had better lung function, and, possibly, better overall survival compared to black beta-agonist users with the Gly16Gly genotype. Our findings highlight the need for additional studies of sufficient size and statistical power to allow examination of outcomes among beta-agonist users of different races and genotypes

Effectiveness and safety of anti-CGRP monoclonal antibodies in patients over 65 years: a real-life multicentre analysis of 162 patients

Background Anti-CGRP monoclonal antibodies have shown notable effectiveness and tolerability in migraine patients; however, data on their use in elderly patients is still lacking, as clinical trials have implicit age restrictions and real-world evidence is scarce. In this study, we aimed to describe the safety and effectiveness of erenumab, galcanezumab and fremanezumab in migraine patients over 65 years old in real-life. Methods In this observational real-life study, a retrospective analysis of prospectively collected data from 18 different headache units in Spain was performed. Migraine patients who started treatment with any anti-CGRP monoclonal antibody after the age of 65 years were included. Primary endpoints were reduction in monthly migraine days after 6 months of treatment and the presence of adverse effects. Secondary endpoints were reductions in headache and medication intake frequencies by months 3 and 6, response rates, changes in patient-reported outcomes and reasons for discontinuation. As a subanalysis, reduction in monthly migraine days and proportion of adverse effects were also compared among the three monoclonal antibodies. Results A total of 162 patients were included, median age 68 years (range 65-87), 74.1% women. 42% had dyslipidaemia, 40.3% hypertension, 8% diabetes, and 6.2% previous cardiovascular ischaemic disease. The reduction in monthly migraine days at month 6 was 10.17.3 days. A total of 25.3% of patients presented adverse effects, all of them mild, with only two cases of blood pressure increase. Headache and medication intake frequencies were significantly reduced, and patient-reported outcomes were improved. The proportions of responders were 68%, 57%, 33% and 9% for reductions in monthly migraine days >= 30%,>= 50%,>= 75% and 100%, respectively. A total of 72.8% of patients continued with the treatment after 6 months. The reduction in migraine days was similar for the different anti-CGRP treatments, but fewer adverse effects were detected with fremanezumab (7.7%). Conclusions Anti-CGRP mAbs are safe and effective treatments in migraine patients over 65 years old in real-life clinical practice