Abstract: SA-PO984
The Role of Autophagy in Neutrophil Extracellular Trap (NET) Formation in CKD
Session Information
- Hypertension and CVD: Mechanisms - II
October 27, 2018 | Location: Exhibit Hall, San Diego Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Hypertension and CVD
- 1403 Hypertension and CVD: Mechanisms
Authors
- Kim, Jwa-kyung, Hallym University, Seoul, Korea (the Republic of)
- Joo, Narae, Halyym University Sacred Heart Hospital, AnYang, Korea (the Republic of)
- Kim, Sung gyun, Hallym University, Antang, Korea (the Republic of)
Background
Increased neutrophil extracellular trap (NET) formation could be an endogenous stimulus of chronic vascular inflammation despite its bacterial killing effect. However, researches about the degree of NET formation in chronic uremic conditions and its relationship with vascular complications have been limited. We assessed the relationship between NETs and vascular endothelial dysfunction in maintenance hemodialysis (MHD) patients, and evaluated the role of autophagy in NET formation in uremia
Methods
To quantify extracellular DNA level, serum cell-free nucleosome was measured between MHD patients (n=60) and healthy volunteer (HV, n=20). Then, neutrophils were isolated and stimulated with phorbol 12-myristate 13-acetate (PMA). The NET formation was visualized with confocal microscopy and the activity of neutrophil elastase (NE) were directly measured to confirm the amount of NETs in both groups. Endothelial dysfunction was measured by flow-mediated dilatation (FMD) of brachial artery using an automated device. The autophagic status were evaluated, and the effect of autophagy inhibition on NET formation was further investigated.
Results
The median basal levels of serum cell-free nucleosome were prominently increased in MHD patients than HV (p<0.001). Also, neutrophils isolated from MHD patients showed an increased NE activity as well as higher NET formation than controls both at basal and activated state, suggesting neutrophil priming in MHD group. The increased extracellular DNA level as well as NE activities were strongly associated with FMD (%) even after adjustments for traditional cardiovascular risk factors and uremic toxin levels (nucleosome: β=-0.429 p=0.001, NE β=-0.429 p=0.001). Moreover, neutrophils isolated from MHD patients showed an increase in autophagy function, especially autophagy induction. Interestingly, after treatment of 3-MA or ammonium chloride, inhibitors of autophagy pathways at early and late stages respectively, the levels of NET formation were markedly augmented, suggesting the protective role of autophagy in uremia.
Conclusion
Increased NETs formation may be one of important contributing factors of vascular endothelial dysfunction in hemodialysis patients. Increased autophagy induction in uremia could be an adaptive response as a protective manner to remove uremic toxins, and the inhibition of autophagy may induce excessive NET formation.