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Epigenetic Modifications to H3K9 in Renal Tubulointerstitial Cells after Unilateral Ureteric Obstruction and TGF-β1 Stimulation.

ABSTRACT: Introduction: Epigenetic regulation of fibrogenesis through post-translational histone modifications (marks) may be a key determinant of progression in renal disease. In this study, we examined the distribution and acquisition of histone 3 Lysine 9 (H3K9) marks after injury and stimulation with the pro-fibrotic cytokine TGF-β1. Our focus was on their presence in activated fibroblasts (myofibroblasts) and epithelial cells (epithelial-mesenchymal transition). Methods and Results: Immunofluorescent microscopy was used to examine global H3K9 acetylation (H3K9Ac) and tri-methylation (H3K9Me3) after unilateral ureteric obstruction (UUO) in mice. Confocal, super resolution microscopy and flow cytometry were used to determine the in vitro effect of TGF-β1 on structural arrangement of these marks, and their relationship with α-smooth muscle actin (αSMA) expression, a marker of myofibroblasts and early EMT. The number of individual histone marks was increased 10 days after UUO (p < 0.05 vs. control), with both marks clearly seen in various cell types including proximal tubules and myofibroblasts. Sub-nuclear microscopy in primary rat renal fibroblasts and a proximal tubule cell line (NRK-52e) showed that H3K9Ac was co-localized with phosphorylated-Ser2 RNA polymerase II (pRNAPol II), while H3K9Me3 was not, consistent with permissive and repressive effects on gene expression respectively. In both cell types H3K9Ac was diffusely distributed throughout the nucleus, while H3K9Me3 was found in compartments resembling the nucleolus, and in the case of the fibroblast, also juxtapositioned with the nuclear membrane. TGF-β1 had no effect on H3K9Ac marks in either cell, but resulted in a redistribution of H3K9Me3 within the fibroblast nucleus. This was unrelated to any change in mitogenesis, but was associated with increased αSMA expression. Conclusion: These findings highlight why it is important to consider the epigenetics of each cell individually, because whilst no overall enrichment occurred, renal myofibroblast differentiation was accompanied by distinct changes in histone mark arrangements.

SUBMITTER: Hewitson TD

PROVIDER: S-EPMC5447091 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Chronic kidney disease (CKD) increases the risk and prevalence of cardiovascular disease (CVD) morbidity and mortality. Recent studies have revealed marked changes in the composition of the microbiome and the metabolome and their potential influence in renal disease and CVD via the accumulation of microbial-derived uremic toxins. However, the effect of unilateral ureteral obstruction (UUO) on the gut microbiome and circulating metabolites is unknown. Male Sprague-Dawley rats were randomized to UUO and sham-operated control groups. Renal histology, colonic microbiota, and plasma metabolites were examined two weeks later. We employed 16S rRNA sequence and untargeted metabolomic analyses to explore the changes in colonic microbiota and plasma metabolites and their relationship with tubulointerstitial fibrosis (TIF). The UUO rats exhibited tubular atrophy and dilatation, interstitial fibrosis and inflammatory cell infiltration in the obstructed kidney. UUO rats showed significant colonic enrichment and depletion of genera. Significant differences were identified in 219 plasma metabolites involved in lipid, amino acid, and bile acid metabolism, which were consistent with gut microbiota-related metabolism. Interestingly, tryptophan and its metabolites kynurenine, 5-hydroxytryptophan and 5-hydroxytryptamine levels, which were linked with TIF, correlated with nine specific genera. Plasma tryptophan level was positively correlated with Clostridium IV, Turicibacter, Pseudomonas and Lactobacillales, and negatively correlated with Oscillibacter, Blautia, and Intestinimonas, which possess the genes encoding tryptophan synthase (K16187), indoleamine 2,3-dioxygenase (K00463) and tryptophan 2,3-dioxygenase (K00453) and their corresponding enzymes (EC:1.13.11.52 and EC:1.13.11.11) that exacerbate TIF. In conclusion, UUO results in profound changes in the gut microbiome and circulating metabolites, events that contribute to the pathogenesis of inflammation and TIF.

Project description:BackgroundUnilateral ureteric-pelvic junction obstruction (UPJO) is the most common cause of obstructive uropathy and may lead to renal impairment and loss of renal function. The current diagnostic approach with renal imaging cannot reliably determine which newborns and infants less than two years of age have a significant obstruction and are at risk for permanent kidney damage. There is therefore no consensus on optimal therapeutic management of unilateral UPJO.ObjectivesTo assess the effects of surgical versus non-surgical treatment options for newborns and infants less than two years of age with unilateral UPJO.Search methodsWe searched the Cochrane Central Register of Controlled Trials (CENTRAL) (Issue 6, 2016), MEDLINE/Ovid, and EMBASE/Ovid databases from their inception to 13 June 2016. We searched the reference lists of potentially relevant studies without using any language restriction. We also searched the following trial registers for relevant registered studies: www.clinicaltrials.gov/; ISRCTN registry (controlled-trials.com/); www.trialscentral.org/; apps.who.int/trialsearch/; www.drks.de/; and www.anzctr.org.au/trialSearch.aspx.Selection criteriaWe selected randomised and quasi-randomised controlled trials comparing surgical with non-surgical interventions for the treatment of unilateral UPJO.Data collection and analysisTwo review authors independently assessed study eligibility and risk of bias of included studies and extracted data. In case of disagreements we consulted a third review author. The data reported in the two included studies did not allow us to perform a meta-analysis.Main resultsWe found only two studies at high risk of bias that were eligible for inclusion in this review. The total sample size, including both trials, was small (n = 107 participants less than six months of age from the UK and USA), and not all prespecified outcome measures were assessed. Reported measures only accounted for the short-term follow-ups. The mean split renal function was not statistically different between the surgical and non-surgical group at the six-month or one-year time point (very low-quality evidence). The surgical group showed a significantly less obstructed drainage pattern and a lower urinary tract dilatation than the non-surgical group (very low-quality evidence). Transfer from the non-surgical group to the surgical group was reported for about one out of five participants. Split renal function after secondary surgical intervention was reported with variable results, but most of the participants reverted to pre-deteriorated values. The studies either provided no or insufficient data on the following outcome measures: postoperative complications, UPJO-associated clinical symptoms, costs of interventions, radiation exposure, quality of life, and adverse effects.Authors' conclusionsWe found limited evidence assessing the benefits and harms of surgical compared to non-surgical treatment options for newborns and infants less than two years of age with unilateral UPJO. The majority of participants in the non-surgical treatment group did not experience any significant deterioration of split renal function, and only about 20% of them underwent secondary surgical intervention, with minor risk of permanent deteriorated split renal function. The study follow-up period was too short to assess the long-term effects on split renal function in both treatment groups. We need further randomised controlled trials with sufficient statistical power and an adequate follow-up period to determine the optimal therapy for newborns and infants less than two years of age with unilateral UPJO.

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Epigenetic Modifications to H3K9 in Renal Tubulointerstitial Cells after Unilateral Ureteric Obstruction and TGF-β1 Stimulation.

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