Abstract 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.
BACKGROUND Mitochondrial impairment and exaggerated inflammation are hallmarks of sarcopenia. Recently, cell-free mitochondrial DNA (cf-mtDNA) has been in the spotlight as an endogenous danger molecule that can potentially elicit inflammation. Yet, its actual impact on sarcopenia, especially in patients with maintenance hemodialysis (MHD), is still at an early stage of investigation. MATERIAL AND METHODS A total of 105 MHD patients were enrolled in this study. The subjects were classified into sarcopenia group (SP) and non-sarcopenia group (NSP) according to the DXA scan and grip strength. Plasma and peripheral blood mononuclear cells (PBMCs) were separated from whole blood. Circulating cf-mtDNA (ccf-mtDNA) was detected using Taq Man RT-qPCR. Cytosolic mtDNA and inflammation- and mitophagy-related genes in PBMCs were quantitated using SYBR Green RT-qPCR. ΔΨm was analyzed using the fluorescent probe JC-1. RESULTS ccf-mtDNA content was significantly higher in SP group than in NSP group. Multivariate regression analysis showed a significant correlation of ccf-mtDNA with sarcopenia after adjusting for potential confounders. A similar trend of increased mtDNA was also observed in the mitochondria-free cytoplasm of PBMCs from SP patients, together with higher expression of TLR9 and IL-6 in this group. Next, using PBMCs as surrogates for mitochondria-rich cells, we found that ΔΨm was dramatically decreased in the SP group. In parallel, the mRNA levels of mitophagy-related genes Parkin and LAMP2 were increased in the SP group. CONCLUSIONS The results obtained demonstrated that ccf-mtDNA, as a potential driver of inflammatory component, may be involved in the pathogenesis of the MHD-related sarcopenia.
A case of hypoglycemic coma caused by a giant borderline phyllodes tumor of the breast has been described. The patient, a 63-year-old woman, was admitted with recurrent unconsciousness. She had a giant breast tumor with decreased blood glucose, insulin, and C-peptide. The patient’s hypoglycemia resolved rapidly after resection of the breast tumor. Pathological examination indicated a borderline phyllodes tumor of the breast, and immunohistochemistry suggested high expression of insulin-like growth factor-2 (IGF-2) in the tumor tissue. A literature review is also included to summarize the clinical characteristics of such patients and to serve as a unique resource for clinical diagnosis and treatment of similar cases.
Abstract 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 × 10 5 copies/mL; p = 0.000). Subsequently, the MHD patients were classified into two groups based on the MtDNA median (4.34 × 10 5 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 × 10 5 copies/mL; p = 0.001) or hemodiafiltration (pre 4.85 vs. post 4.09 × 10 5 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.
Abstract Background Mitochondrial DNA (MtDNA) exposed to the extracellular space due to cell death and stress has immunostimulatory properties. However, the clinical significance of circulating MtDNA in maintenance hemodialysis (MHD) patients and the precise mechanism of its emergence have yet to be investigated. Methods This cross‐sectional study consisted of 52 MHD patients and 32 age‐ and sex‐matched healthy controls. MHD patients were further categorized into high and low circulating cell‐free MtDNA (ccf‐MtDNA) groups based on the median value. Copy number of MtDNA was quantified using TaqMan‐based qPCR. Plasma cytokines were measured using ELISA kits. Reactive oxygen species (ROS) and mitochondrial membrane potential (Δψm) in peripheral blood mononuclear cells (PBMCs) were detected using DCFH‐DA or JC‐1 staining. Results The copy numbers of ccf‐MtDNA in patients with MHD were higher than those in healthy controls, and these alterations were correlated with changes of cytokines TNF‐α and IL‐6. Adjusted model in multivariate analysis showed that the presence of anuria and longer dialysis vintage were independently associated with higher levels of ccf‐MtDNA. Meanwhile, although not statistically significant, an inverse correlative trend between urinary MtDNA and ccf‐MtDNA was observed in patients with residual urine. Afterward, using PBMCs as surrogates for mitochondria‐rich cells, we found that patients in the high ccf‐MtDNA group exhibited a significantly higher ROS production and lower Δψm in cells. Conclusions Our data suggested that changes in ccf‐MtDNA correlate with the degree of inflammatory status in MHD patients, and that the excessive MtDNA may be caused by mitochondrial dysfunction and reduced urinary MtDNA excretion.
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