Indoxyl sulphate activates cardiac fibroblasts with enhanced collagen synthesis, upregulated angiotensin-neprilysin system, and paracrine induction of cardiomyocyte hypertrophy

• Published in: Vascular pharmacology 2018-04, Vol.103-105, p.48-48
• Main Authors: Barisone, C., Lazzarini, E., Ruggeri, C., Garibaldi, S., Fabbi, P., Verzola, D., Ravera, S., Brunelli, C., Ghigliotti, G., Ameri, P.
• Format: Article
• Language: English
• Subjects: Actin; Activation; Angiotensin; Angiotensinogen; Brain natriuretic peptide; Cardiomyocytes; Cardiovascular disease; Collagen; Conditioning; Coronary artery disease; Drinking water; Endopeptidases; Fibroblasts; Fibrosis; Flow cytometry; Glycolysis; Heart; Heart diseases; Histology; Hypertrophy; Immunocytochemistry; Lysates; Markers; Mice; Muscles; Myosin; Myostatin; Neonates; Neprilysin; Oxidative stress; Peptides; Polymerase chain reaction; Smooth muscle; Studies; Sulfates; Synthesis; Tryptophan; Ventricle; Western blotting
• ISSN: 1537-1891; 1879-3649
• DOI: 10.1016/j.vph.2017.12.005

Objective: Left ventricular hypertrophy (LVH) is common in chronic kidney disease (CKD). Cardiac fibroblast (Fib)-driven myocardial fibrosis is being recognized as important as cardiomyocyte hypertrophy in CKD-related LVH. but the factors triggering it are only partially known. Here, we investigated whether a role may be played by indoxyl sulphate (IS), a tryptophan metabolite that accumulates in CKD since early stages. Methods: Neonatal mouse Fib were treated with 50 μM IS. a concentration found in moderate CKD. with or without the IS antagonist. CH-22319I. Oxidative stress was evaluated by using the CellROX assay, proliferation by BrdU incorporation and flow cytometry for CFSE, α-smooth muscle actin (αSMA). selected paracrine mediators, and the neprilysin-angiotensin (Ang) axis by RT-PCR, western blotting and/or immunocytochemistry. and collagen production by RT-PCR and picrosirius red staining. After incubating neonatal mouse ventricular cardiomyocytes (mNVCM) with the conditioned medium of control or IS-treated Fib. β-myosin heavy chain (β-MHC) and atrial and B-type natriuretic peptide expression was analyzed by RT-PCR and glycolysis by enzymatic assays. Adult C57BL/6 mice were given drinking water with or without IS [1 mg/mL)for 12 weeks, after which cardiac histology and markers of Fib activation and cardiomyocyte hypertrophy were examined. Results: IS enhanced Fib proliferation. αSMA immunopositivity and collagen expression and synthesis. Moreover, it increased the levels of TNF-α and myostatin. an emerging mediator of IS action. The genes encoding angiotensinogen, Ang-converting enzyme, and Ang receptor type 1 were also upregulated by IS. as well as the gene for neprilysin, an endopeptidase that cleaves Angll and - mostly -natriuretic peptides. All these effects were counteracted by CH-223191. Compared with control cells. mNVCM incubated with the conditioned medium of IS-primed Fib exhibited higher levels of β-MHC and heightened activity of glycolytic enzymes, suggesting cellular hypertrophy. The hearts of mice treated with IS displayed histological signs of cardiomyocyte hypertrophy and initial interstitial fibrosis. At the time of this abstract, we have also observed in the lysates of IS-exposed hearts an increase in the majority of the markers of Fib activation evaluated in vitro, as well as heightened β-MHC and natriuretic peptide expression and glycolysis. Conclusions: IS alone may contribute to CKD-associated LVH by eliciting Fib activation w