Eringa, Etto C

Vascular calcification is a strong predictor of cardiovascular mortality and lacks effective treatment. The transformation of vascular smooth muscle cells (VSMCs) into osteoblast-like phenotypes is a key driver of calcification. This study identifies a regulatory role for Hyaluronan (HA) in VSMC osteogenic differentiation and arterial calcification. Human aortic VSMCs stimulated with high phosphate and/or pro-inflammatory cytokines (IL6 and TGF-β1) exhibited increased RUNX2, alkaline phosphatase and osteopontin expression, along with reduced contractility and elevated calcium deposition. This corresponded with reduced HA deposition and downregulation of HA synthase enzymes (HAS1, HAS2), Hyaluronidase enzymes (Hyal1), and HA binding proteins (CD44, TSG-6), whilst HAS3 and versican were upregulated. Comparable alterations in HA and protein expression were observed in an in vivo model of arterial calcification using vitamin K-deficient warfarin-fed mice. Pharmacological inhibition of HA synthesis, enzyme-mediated HA degradation and siRNA/plasmid modulation of HAS isoenzymes demonstrated a possible functional link between HA regulation and VSMC osteogenic differentiation. This study establishes HA and its associated binding proteins as key regulators of arterial calcification, highlighting a novel pathway for potential therapeutic intervention.

ABSTRACT Background and hypothesis End-stage renal disease patients require peritoneal dialysis (PD) as a life-saving therapy; however, they continue to experience systemic inflammation and increased cardiovascular pathology. These complications can be exacerbated by exposure to PD solutions (PDS) containing glucose. This highlights the clinical unmet need for novel osmotic agents to replace glucose. Here, we tested troxerutin, a Food and Drug Administration–approved drug, as a potential osmotic agent. Methods To evaluate troxerutin osmotic and non-toxic effects, in vitro and in vivo experiments were carried out using artificial membranes, mice and cultured human mesothelial cells (MCs). The local and systemic consequences of chronic peritoneal exposure to PDS associated to renal insufficiency were investigated in a preclinical model. 5/6 nephrectomized C57BL/6J mice were daily exposed to glucose- or troxerutin-PDS for 60 days, then evaluating tissue damage, proinflammatory markers and cardiac damage. Results In vitro and in vivo studies revealed that troxerutin exhibits similar osmotic and ultrafiltration capacities to glucose, but with colloidal properties. Moreover, only glucose, but not troxerutin, reduced MC viability, induced mesothelial-to-mesenchymal transition, and increased damage markers (such as interleukin-6 and vascular endothelial growth factor A). In the preclinical model, long-term treatment with glucose-PDS, but not troxerutin-PDS, significantly increased peritoneal membrane thickening, tissue proinflammatory markers (evaluated in peritoneum, kidney, heart and aorta) and cardiovascular damage (cardiac hypertrophy and fibrosis) in mice. These preclinical data clearly demonstrate the wide deleterious effects of chronic peritoneal exposure to glucose-containing PDS in mice with kidney insufficiency and that the replacement of glucose with troxerutin notably reduces these effects. Conclusion Troxerutin emerges as a more biocompatible alternative to glucose as an osmotic agent for PD therapy, exhibiting no adverse local or systemic side effects in preclinical studies. This research presents a novel approach to reduce cardiovascular complications of PD in end-stage kidney disease.

Background Atherosclerosis is highly prevalent in people with chronic kidney disease (CKD), including those receiving peritoneal dialysis (PD). Although it is lifesaving, PD induces profound systemic inflammation, which may aggravate atherosclerosis. Therefore, the hypothesis is that this PD‐induced inflammation aggravates atherosclerosis via immune cell activation. Methods and Results ApoE −/− mice were subjected to a 5/6 nephrectomy to induce CKD. Three weeks later, mice were fed a high‐cholesterol diet. Half of the nephrectomized mice then received daily peritoneal infusions of 3.86% Physioneal for 67 further days (CKD+PD) until the end of the experiment, and were compared with mice without CKD. Sham operated and PD‐only mice were additional controls. CKD+PD mice displayed more severe atherosclerotic disease than control mice. Plaque area increased, and plaques were more advanced with a vulnerable phenotype typified by decreased collagen content and decreased fibrous cap thickness. Increased CD3 + T‐cell numbers were present in plaques and perivascular adipose tissue of CKD and CKD+PD mice. Plaques of CKD+PD mice contained more iNOS + immune cells. Spleens of CKD+PD mice showed more CD4 + central memory, terminally differentiated type 1 T‐helper (Th1), Th17, and CX3C motif chemokine receptor 1 + (CX3CR1) CD4 + T‐cells with less regulatory and effector T‐cells. Conclusions PD‐fluid exposure in uremic mice potentiates systemic and vascular T‐cell‐driven inflammation and aggravates atherosclerosis. PD polarized CD4 + T‐cells toward an inflammatory Th1/Th17 phenotype, and increased CX3CR1 + CD4 + T‐cells, which are associated with vascular homing in CKD‐associated atherosclerosis. Targeting CD4 + T‐cell activation and CX3CR1 + polarization has the potential to attenuate atherosclerosis in PD patients.