#1186 Novel T-cell subsets as early non-invasive biomarkers of vascular damage in chronic kidney disease progression
Authors: Virgala Julia Martin , Miranda-Prieto Daniel , Astudillo-Cortés Elena , Bande-Fernández Joaquin , Fernandez-Mariño Belinda , Naves-López Teresa , Llaneza-Faedo Mónica , Gacía-Gil-Albert Carmen , Suarez Ana , Naves-Díaz Manuel , Rodriguez-Carrio Javier , Carrillo-Lopez Natalia 
Published: May 2024

Abstract

Background and Aims
The exploration of early biomarkers for diagnosing vascular alterations in CKD-MBD holds significant clinical potential. Previous evidence has demonstrated profound alterations in immune cell populations linked to vascular homeostasis in CKD dialysis patients. This study aimed to evaluate the utility of immune cell populations as early and progressive biomarkers for non-dialysis CKD patients, examining their correlation with vascular damage.

Method
A total of 43 non-dialysis CKD patients and 38 sex- and age-matched controls were included in the study. Patients were categorized into four groups based on their estimated glomerular filtration rate (eGFR): CKD-2/3a, CKD-3b, CKD-4, and CKD-5. The assessment of left carotid adventitial neovascularization and intima-media thickness (cIMT) was conducted using ultrasensitive ultrasonography without contrast, specifically employing Superb Microvascular Image (SMI) technology. Pulse wave velocity (PWV) was measured to determine aortic stiffness, utilizing the Complior Analyzer. Immunosescencent T-cells (CD4+CD28null), angiogenic T-cells (Tang) (CD3+CD31+CD184+) and their subsets (CD4+Tang, CD8+Tang and CD28nullTang) were quantified by flow cytometry in Peripheral Blood Mononuclear Cells.

Results
No significant differences in age and body mass index were observed between the control group and the four CKD stages. Notably, the values of estimated glomerular filtration rate (eGFR) exhibited a significant and progressive decrease, as indicated in the Table 1. Biochemical parameters related to CKD-MBD are also detailed in the same table.
The carotid intima-media thickness (cIMT) was found to be significantly higher in CKD-5 compared to CKD 2-3a (CKD 2-3a = 0.66 ± 0.14 mm, CKD-5 = 0.80 ± 0.12 mm, p = 0.03). In patients at stage 4 of CKD, there was an increased number of adventitial vasa vasorum (control = 0.53 ± 1.33, CKD-4 = 1.67 ± 2.04, p = 0.0009) and a greater area of adventitial neovascularization in the carotid artery compared to the control group (control = 0.51 ± 1.31%, CKD-4 = 2.67 ± 2.27%, p = 0.0003).
PWV was significantly higher in CKD-5 (control = 10.81 ± 2.01 m/s, CKD-5 = 12.91 ± 3.70 m/s, p = 0.045).
Additionally, a significant correlation was observed between PWV and both the number of adventitial vasa vasorum at the carotid artery (r = 0.24, p = 0.028) and the area of adventitial neovascularization (r = 0.34, p = 0.002).
CD4+CD28null T-cells were increased in CKD patients compared to control group (control = 24.99[5.52], CKD = 27.35[8.58], p = 0.004). Although no differences were found in total levels of Tang in CKD patients (control = 1.64 ± 0.89, CKD= 1.5 ± 1.02, p = 0.757), a strong negative correlation was observed across CKD stages (trend analysis for stages: r = −0.361, p = 0.017). Moreover, CKD patients had altered CD8+ and CD4+ Tang frequencies (CD4+Tang: control = 39.52[18.46], CKD = 33.60[12.84], p = 0.054; CD8+Tang: control = 40.03[14.38], CKD = 48.25[13.16], p = 0.012) and Tang CD28null were increased in CKD patients (control = 44.14[11.99], CKD = 48.62[12.08], p = 0.004). Finally, Tang frequency was significantly correlated with the number of adventitial vasa vasorum (r = 0.368, p = 0.032), area of adventitial neovascularization (r = −0.401, p = 0.019), PWV (r = −0.341, p = 0.048) and cIMT (r = −0.364, p = 0.034).

Conclusion
Carotid adventitial neovascularization, cIMT and PWV demonstrated an increase in advanced CKD stages, implying that they may possess limited clinical utility as early markers of vascular damage in the initial stages of CKD. Immunosenescence and vascular damage traits were found across the CKD spectrum. Altered Tang frequency may be considered a progressive biomarker of impaired vascular homeostasis in CKD.