Chronic Kidney Disease (CKD) patients are at high risk of presenting with arterial calcification or stiffness, which confers increased cardiovascular mortality and morbidity. In recent years, it has become evident that VC is an active process regulated by various molecules that may act as inhibitors of vessel mineralization. Matrix Gla Protein (MGP), one the most powerful naturally occurring inhibitors of arterial calcification, requires vitamin K as a co-factor in order to undergo post-translational γ-carboxylation and phosphrorylation and become biologically active. The inactive form of MGP (dephosphorylated, uncarboxylated dp-ucMGP) reflects vitamin K deficiency and has been repeatedly associated with surrogate markers of VC, stiffness, and cardiovascular outcomes in CKD populations. As CKD is a state of progressive vitamin K depletion and VC, research has focused on clinical trials aiming to investigate the possible beneficial effects of vitamin K in CKD and dialysis patients. In this study, we aim to review the current evidence regarding vitamin K supplementation in uremic patients.

Maladaptive activation of the immune system plays a key role in the pathogenesis of chronic kidney disease (CKD). Our aim was to investigate differences in circulating immune cells between type 2 cardiorenal syndrome (CRS-2) patients and CKD patients without cardiovascular disease (CVD). CRS-2 patients were prospectively followed up, with the primary endpoint being all-cause and cardiovascular mortality. Method: A total of 39 stable males with CRS-2 and 24 male CKD patients matched for eGFR (CKD-EPI) were enrolled. A selected panel of immune cell subsets was measured by flow cytometry. Results: Compared to CKD patients, CRS-2 patients displayed higher levels of proinflammatory CD14++CD16+ monocytes (p = 0.04) and T regulatory cells (Tregs) (p = 0.03), lower lymphocytes (p = 0.04), and lower natural killer cells (p = 0.001). Decreased lymphocytes, T-lymphocytes, CD4+ T-cells, CD8+ T-cells, Tregs, and increased CD14++CD16+ monocytes were associated with mortality at a median follow-up of 30 months (p < 0.05 for all). In a multivariate model including all six immune cell subsets, only CD4+ T-lymphocytes remained independent predictors of mortality (OR 0.66; 95% CI 0.50–0.87; p = 0.004). Conclusion: Patients with CRS-2 exhibit alterations in immune cell profile compared to CKD patients of similar kidney function but without CVD. In the CRS-2 cohort, CD4+ T-lymphocytes independently predicted fatal cardiovascular events.

The role of immune system components in the development of myocardial remodeling in chronic kidney disease (CKD) and kidney transplantation remains an open question. Our aim was to investigate the associations between immune cell subpopulations in the circulation of CKD patients and kidney transplant recipients (KTRs) with subclinical indices of myocardial performance. We enrolled 44 CKD patients and 38 KTRs without established cardiovascular disease. A selected panel of immune cells was measured by flow cytometry. Classical and novel strain-related indices of ventricular function were measured by speckle-tracking echocardiography at baseline and following dipyridamole infusion. In CKD patients, the left ventricular (LV) relative wall thickness correlated with the CD14++CD16− monocytes (β = 0.447, p = 0.004), while the CD14++CD16+ monocytes were independent correlates of the global radial strain (β = 0.351, p = 0.04). In KTRs, dipyridamole induced changes in global longitudinal strain correlated with CD14++CD16+ monocytes (β = 0.423, p = 0.009) and CD4+ T-cells (β = 0.403, p = 0.01). LV twist and untwist were independently correlated with the CD8+ T-cells (β = 0.405, p = 0.02 and β = −0.367, p = 0.03, respectively) in CKD patients, whereas the CD14++CD16+ monocytes were independent correlates of LV twist and untwist in KTRs (β = 0.405, p = 0.02 and β = −0.367, p = 0.03, respectively). Immune cell subsets independently correlate with left ventricular strain and torsion-related indices in CKD patients and KTRs without established CVD.

Aberrant signaling pathways of the acquired immune system are implicated in the development of cardiovascular disease (CVD) and chronic kidney disease (CKD) phenotypes. Understanding the complex abnormalities of lymphocyte subpopulations in CKD is a prerequisite for elucidating their implication in uremic cardiomyopathy. T cell subsets display various patterns of association with indices of myocardial function in both experimental and clinical CKD models. The role of Tregs in CVD and CKD has attracted significant research interest. Although experimental data suggest a protective role of Tregs from the development of arterial hypertension- and pressure overload-induced myocardial hypertrophy, there might be a change in the regulatory T cell (Treg) phenotype towards a profibrotic one in the settings of CKD and heart failure. Depletion of B lymphocytes is a hallmark of CKD and heart failure, bearing adverse prognostic significance, yet evidence of B lymphocytes’ involvement in the pathogenesis of myocardial damage is currently lacking. Considering that myocardial remodeling is the final outcome of diverse pathogenic processes targeting the heart, the aim of this review is to present the evidence available up to now regarding the role of acquired immune cells in the pathogenesis of the structural and functional alterations of the myocardium in CKD.