Endothelial progenitor cell biology in ankylosing spondylitis

Humoral and Cellular Patterns of Early Endothelial Progenitor Cells in Relation to the Cardiovascular Risk in Axial Spondylarthritis

Background

Spondylarthritis (SpA) significantly affects sacroiliac, intervertebral and peripheral joints. Patients with SpA suffer from increased cardiovascular risk (CVR). The endothelial progenitor cell (EPC) system critically perpetuates vascular repair. The aim of the study was to evaluate circulating EPCs in axial (ax)SpA with special attention on parameters of disease activity and CVR.

Methods

Disease activity and functional impairment were quantified in 50 axSpA patients by using standardized parameters (Bath ankylosing spondylitis disease activity index (BASDAI), C-reactive protein (CRP), finger-floor distance (FFD) and Ott’ sign). Circulating EPCs and EPC regeneration were analyzed (fluorescence-activated cell sorting (FACS) and colony-forming unit (CFU) assay). Serum vasomodulatory mediators were quantified by enzyme-linked immunosorbent assay (ELISA).

Results

EPC colony numbers were lower in axSpA as compared to controls. Females displayed more colonies than males. In addition, fewer colonies were observed in smokers, in patients with a BASDAI of below 4 and in hypertension. Circulating CD133⁺/KDR⁺ cells did not differ between the groups. Follow-up analysis (33 months later) did not show any differences in gender, colony formation, CD133⁺/KDR⁺ cells or serum levels of vasomodulatory mediators if related to the categories of BASDAI, Ott’ sign or FFD.

Conclusions

EPC colony formation is significantly affected in axSpA with particularly low levels in males. EPC-related parameters do not allow predicting disease activity-related or functional parameters nor are they useful for CVR assessment in SpA.

Endothelial dysfunction in patients with ankylosing spondylitis

Ankylosing spondylitis (AS) is associated with accelerated atherosclerosis and enhanced cardiovascular morbidity and mortality compared to the general population. The mechanisms and mediators of this phenomenon have not been fully explained, but an expanding body of evidence demonstrates that increased cardiovascular risk in AS is heralded by endothelial dysfunction. We performed a literature review using the PubMed database from the year 2006 up to 2018. In this article we review the epidemiology, current evidence for impaired endothelial function, potential mechanisms and markers controlling this dysfunction, and finally we summarize the data regarding the efficacy of pharmacotherapy in reducing endothelial dysfunction in patients suffering from AS.

Predictors of endothelial dysfunction and atherosclerosis in rheumatoid arthritis in Indian population

Objective

Cardiovascular (CV) disease is leading cause of mortality in rheumatoid arthritis (RA). Dysfunction of the vascular endothelium is a hallmark of most conditions that are associated with atherosclerosis and is therefore an early feature in atherogenesis. Biomarkers for rapid evolution of CV complications would be highly desirable for risk stratification. Finally, predictive biomarkers for cardiovascular risk would allow tailoring therapy to the individual. We assessed endothelial function and atherosclerosis utilizing carotid intima-media thickness (CIMT) in RA in context of clinical and laboratory markers in Indian RA population.

Methods

We performed a prospective study of 35 consecutive RA patients and 25 age- and sex matched healthy controls. Patients with traditional CV risk factors were excluded. Flow mediated dilatation (FMD) as measures of endothelial function and CIMT as measures of atherosclerosis were assessed. Disease-specific measures, inflammatory measures, serum cytokines, serum nitrite, lipids and endothelial progenitor cells (EPCs) were estimated.

Results

FMD was significantly lower in RA (6.53% ± 1.81%) compared to controls (10.77% ± 0.53%; p < 0.001). CIMT (mm) was significantly increased in RA (0.62 ± 0.17) vs. controls (0.043 ± 0.07; p = 0.003). In RA patients, FMD% inversely correlated with CIMT, CRP, DAS-28, TNF-α, serum nitrite and positively correlated with EPC. CIMT correlated with age, DAS-28, IL-6, HDL, LDL, and inversely correlated with EPC.

Conclusions

In the present study, FMD and CIMT were impaired in RA, indicating endothelial dysfunction and accelerated atherosclerosis respectively. CRP, TNF-α, serum nitrite, DAS-28 and depleted EPC population predicted endothelial dysfunction. Age, IL-6, HDL, LDL and depleted EPC population predicted accelerated atherosclerosis.

Endothelial Progenitor Cells as a Marker of Endothelial Dysfunction and Atherosclerosis in Ankylosing Spondylitis: A Cross-Sectional Study

Endothelial progenitor cells (EPCs) have reparative potential in overcoming the endothelial dysfunction and reducing cardiovascular risk. EPC depletion has been demonstrated in the setting of established atherosclerotic diseases. We evaluated whether reduced EPCs population are associated with endothelial dysfunction, subclinical atherosclerosis, and inflammatory markers in ankylosing spondylitis (AS) patients without any known traditional cardiovascular risk factor. We performed a cross-sectional study of 30 consecutive AS patients and 25 age- and sex-matched healthy controls. Patients with traditional cardiovascular risk factors were excluded. Circulating EPCs (CD34⁺/CD133⁺) were quantified by flow cytometry. The assessment of endothelial function by brachial artery flow-mediated dilatation (FMD) and ultrasound assessment of carotid intima-media thickness (CIMT) was measured in both the groups. EPCs cells were significantly (0.020 ± 0.001 vs. 0.040 ± 0.010%, p < 0.001) reduced in patients with AS compared with healthy controls. Endothelial function (7.35 ± 2.54 vs. 10.27 ± 1.73, p = 0.002), CIMT (0.63 ± 0.01 vs. 0.35 ± 0.02, p < 0.001), and inflammatory markers were also significantly (p < 0.01) altered as compared with controls. EPCs inversely correlated with tumor necrosis factor (TNF)-α and C-reactive protein (CRP) and positively correlated with endothelial function. Present study results demonstrate depleted EPC population in AS patients compared with controls. Increased level of CRP and TNF-α appears to play a key role in EPC depletion and the latter contributes to endothelial dysfunction and atherosclerosis in AS. EPC population would, therefore, represent an attractive measure of endothelial dysfunction and accelerated atherosclerosis disease associated with AS.

Challenges and opportunities for stem cell therapy in patients with chronic kidney disease

Chronic kidney disease (CKD) is a global health care burden affecting billions of individuals worldwide. The kidney has limited regenerative capacity from chronic insults, and for the most common causes of CKD, no effective treatment exists to prevent progression to end-stage kidney failure. Therefore, novel interventions, such as regenerative cell-based therapies, need to be developed for CKD. Given the risk of allosensitization, autologous transplantation of cells to boost regenerative potential is preferred. Therefore, verification of cell function and vitality in CKD patients is imperative. Two cell types have been most commonly applied in regenerative medicine. Endothelial progenitor cells contribute to neovasculogenesis primarily through paracrine angiogenic activity and partly by differentiation into mature endothelial cells in situ. Mesenchymal stem cells also exert paracrine effects, including proangiogenic, anti-inflammatory, and antifibrotic activity. However, in CKD, multiple factors may contribute to reduced cell function, including older age, coexisting cardiovascular disease, diabetes, chronic inflammatory states, and uremia, which may limit the effectiveness of an autologous cell-based therapy approach. This Review highlights current knowledge on stem and progenitor cell function and vitality, aspects of the uremic milieu that may serve as a barrier to therapy, and novel methods to improve stem cell function for potential transplantation.