Background Chronic kidney disease (CKD) patients sustain a fairly high prevalence of cardiovascular disease (CVD). Microvascular inflammation is an early manifestation of CVD, and the released mitochondrial DNA (MtDNA) has been proposed to be a crucial integrator of inflammatory signals. Herein, the aim of this study was to determine the relationship between CVD, microvessel, and circulating MtDNA in the settings of uremia. Methods Forty-two maintenance hemodialysis (MHD) patients and 36 health controls were enrolled in this study. Plasma cell-free MtDNA was detected by TaqMan-based qPCR assay. CVD risk markers including high-sensitive C-reactive protein (Hs-CRP), monocyte chemoattractant protein-1 (MCP-1), fibrinogen, and erythrocyte sedimentation rate (ESR) were measured by standard assays. Ten-year CVD risk was calculated from the Framingham risk score (FRS) model. In vitro study, human cardiac microvascular endothelial cells (HCMECs) were incubated with normal or uremic serum, with or without exogenous MtDNA. Intracellular toll-like receptor 9 (TLR9), adhesion molecule 1 (ICAM-1), MCP-1 and tumor necrosis factor-α (TNF-α) and cytosolic MtDNA were detected by qPCR. Results Plasma MtDNA in MHD patients was significantly higher than healthy controls (4.74 vs. 2.41 × 105 copies/mL; p = 0.000). Subsequently, the MHD patients were classified into two groups based on the MtDNA median (4.34 × 105 copies/mL). In stratified analyses, the levels of Hs-CRP (5.02 vs. 3.73 mg/L; p = 0.042) and MCP-l (99.97 vs. 64.72 pg/mL; p = 0.008) and FRS (21.80 vs. 16.52; p = 0.016) in the high plasma MtDNA group were higher than those in the low plasma MtDNA group. In vitro study, we found that exogenous MtDNA aggravated uremic serum-induced microvascular inflammation (ICAM-1 and TNF-α) in HCMECs (all p < 0.05). Besides, the addition of MtDNA to the medium resulted in a further increase in cytosolic MtDNA and TLR9 levels in uremic serum-treated cells (all p < 0.05). In patients with MHD, MtDNA levels in plasma were significantly reduced after a single routine hemodialysis (pre 4.47 vs. post 3.45 × 105 copies/mL; p = 0.001) or hemodiafiltration (pre 4.85 vs. post 4.09 × 105 copies/mL; p = 0.001). These two approaches seem similar in terms of MtDNA clearance rate (21.26% vs. 11.94%; p = 0.172). Conclusions Overall, the present study suggests that MtDNA released into the circulation under the uremic toxin environment may adversely affect the cardiovascular system by exacerbating microvascular inflammation, and that reducing circulating MtDNA might be a future therapeutic strategy for the prevention of MHD-related CVD.

Objective There is a paucity of research on the association between bile acids (BAs) levels and all-cause death in patients with diabetes mellitus (DM) on maintenance hemodialysis (MHD). This study aimed to investigate the clinical characteristics of patients with DM on MHD according to different BAs levels and their impact on prognosis. Methods A retrospective cohort of 1,081 patients on hemodialysis at Xindu People’s Hospital and the First Affiliated Hospital of Chengdu Medical College were enrolled. Demographic and clinical characteristics were collected. The relationship between BAs and all-cause death risk was fitted using restricted cubic splines (RCS), and the BAs cutoff value was calculated. Patients were divided into low and high BAs groups based on the cutoff value. The primary endpoint was all-cause death and the secondary outcomes were deaths from cardiovascular events. Results Finally, 387 patients with DM on MHD were included. The median BAs level of all patients was 4.0 μmol/L. The RCS-based BAs cutoff value was 3.5 μmol/L. The BAs levels correlated negatively with total cholesterol, low-density lipoprotein, and blood calcium levels. During the follow-up, 21.7% of the patients died. The multivariate Cox regression analysis demonstrated that patients with DM on MHD with higher BAs were associated independently with a decreased risk of all-cause death (HR =0.55; 95% CI, 0.35–0.81, p = 0.01) compared to those with lower BAs levels. Conclusions Higher BAs levels were associated with lower lipid levels in patients with DM on MHD. BAs is an independent risk factor for all-cause death in patients with DM on MHD.

Background Previous studies have shown a role of mitochondrial DNA (MtDNA) in innate immunity. However, the specific role of MtDNA in chronic kidney disease (CKD)-related cardiovascular disease (CVD) remains elusive. This study was designed to investigate the potential relationship between circulating MtDNA and CVD in maintenance hemodialysis (MHD) patients, and to examine the damaging effect of exogenous MtDNA on cardiac microvascular endothelial cells (CMECs) in the uremic milieu. Methods Forty-two MHD patients and 36 health controls were enrolled in this study. Plasma cell-free MtDNA was detected by TaqMan-based qPCR assay. The CVD risk markers including high-sensitive C-reactive protein (Hs-CRP), monocyte chemoattractant protein-1 (MCP-1), fibrinogen, and erythrocyte sedimentation rate (ESR) were measured by using standard assays. The ten-year cardiovascular risk was assessed using the framingham risk score (FRS). Dialysis systems in MHD patients were used to evaluate the effect of different dialysis modes on the clearance of circulating MtDNA. In vitro study, human cardiac microvascular endothelial cells (HCMECs) were incubated with normal or uremic serum with or without exogenous MtDNA stimulation. Intracellular toll-like receptor 9 (TLR9), adhesion molecule 1 (ICAM-1), MCP-1 and tumor necrosis factor-α (TNF-α) mRNA levels and cytosolic MtDNA contents were detected by qPCR. Results Plasma MtDNA was significantly elevated in patients with MHD relative to healthy controls. The MHD patients were subsequently classified into two groups based on the median value of MtDNA. In stratified analyses, the levels of Hs-CRP and MCP-l, and FRS in the high plasma MtDNA group were higher than those in the low plasma MtDNA group. In vitro study, exogenous MtDNA aggravated uremic serum-induced upregulation of ICAM-1 and TNF-α in HCMECs. Also, the addition of MtDNA to the medium resulted in increased cytosolic MtDNA amounts and TLR9 mRNA levels in uremic serum-treated cells. Single routine hemodialysis and hemodiafiltration could partially reduce plasma MtDNA in MHD patients. These two methods seem similar in terms of MtDNA clearance. Conclusions We concluded that MtDNA released into the circulation under the uremic toxin environment may has a detrimental effect on cardiovascular system through aggravating microvascular inflammation, and that reducing circulating MtDNA might be a future therapeutic strategy for the prevention of MHD-related CVD.