Inderjeet Verma (Senior Research Fellow) Endothelial progenitor cell biology in psoriatic arthritis patients: from biomarker to therapeutic agent Inderjeet Verma (Senior Research Fellow) Department of Pharmaceutical Sciences and Drug Research, Punjabi University, Patiala, India. Cardio-Rheuma & Healing Touch City Clinic, Chandigarh

Disclosures… This study was supported by University Grant Commission (UGC), New Delhi, F.No. 10-15/2007 (SA-1) No other relevant financial involvement with any other organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the presentation apart from those disclosed. No assistance was utilized in the production of this presentation

Study Background….. Arthritis Rheum. 2007;57)6):1074-80. Psoriatic arthritis (PsA) is an immune-mediated inflammatory arthritis associated with psoriasis. Annual incidence of PsA ranges from 0.1 to 23.1 per 100,000. Int J Rheum. 29012. Article ID 71432 Cardiovascular disease is one of the leading causes of death in patients with PsA. Arthritis Rheum. 2007;57)6):1074-80. Chronic immune-mediated inflammation plays a key role in the pathogenesis of atherosclerosis in PsA, acting independently and/or synergistically with the conventional risk factors. Semin Arthritis Rheum. 2004;34:585-92. Endothelial progenitor cells (EPCs) are bone-marrow derived stem cells that contribute to vascular homeostasis and may serve as a circulating pool of cells to improve endothelial dysfunction. Annu Rev Med. 2005;56:79-101.

Study Background….new possibilities EPCs: better predictor of endothelial dysfunction than conventional risk factors; predict occurrence of CV events & cardiovascular death. Arterio Throm Vas Biol 2006;26:257-266. Depletion of EPC population have been shown in RA, recently in AS and other RDs. Arthritis Rheum. 2009; 60:3168–79 Int J Rheum Dis. 2014.doi: 10.1111/1756-185X.12487 EPCs contribute to the enhanced CV risk & predict the occurrence of CV events & cardiovascular death. Previously EPC population has been assessed in a heterogeneous population of with equivocal results in psoriatic arthritis (PsA) patients with confounding factors. Rheumatol Int. 2009;29: 257-62 .

Potential mechanisms involved in reduced EPC levels in rheumatic disease Westerweel PE and Verhaar MC (2009) Endothelial progenitor cell dysfunction in rheumatic disease Nat Rev Rheumatol doi:10.1038/nrrheum.2009.81

Study Objective…. The aim of this study was to investigate EPC population in PsA patients in the absence of traditional cardiovascular risk factors. Its relationship with surrogate of atherosclerosis and clinical parameters of disease activity as well as measures of inflammatory markers.

Flow Mediated Dilatation (FMD) Carotid intimal medial thickness (CIMT) STUDY DESIGN Screening Exclusion criteria Inclusion criteria Cardiovascular/cerebrovascular disorders Diabetes mellitus, thyroid disorders, malignancy, Renal or liver insufficiency, Pregnant or breastfeeding women Previous use of TNFi, ACE inhibitors, ARBs Statin, PPAR agonists, steroids, estrogen or EPO Patients ages ≥18 years with PsA classified according to CASPAR criteria Normotensive. Non-smokers. 20 healthy controls were recruited from the clinic staff. . Psoriatic arthritis n=22 Healthy controls n=20 Assessment Assessment of inflammatory markers: ESR & CRP Assessment of Disease Activity: DAS-28 and DAPSA Proinflammatory Cytokines: TNF-α, IL-6 & IL-1) EPC (CD34+/CD133) by Flow Cytometry (canto II, BD Bio Sciences) Flow Mediated Dilatation (FMD) Carotid intimal medial thickness (CIMT) .

Table 1. Demographic and laboratory characteristics of the participants Variable Psoriatic Arthritis Healthy Controls   P value n 22 20 Age (years) 45.1 ± 13.8 43.9 ± 12.6 0.49 Sex (men/women) 13/9 12/8 0.33 BMI (kg/m2) 26.3 ± 4.76 25.2 ± 3.2 0.27 Smoking (number) - Systolic BP (mm Hg) 126.2 ± 9.42 123.0 ± 12.0 0.36 Diastolic BP (mm Hg) 79.8 ± 8.6 78.3 ± 8.0 0.57 Disease Duration (years) 7.5 ± 4.6 HbA1c (%) 5.28 ±1.6 5.08 ± 0.6 0.40 Total cholesterol (mg/dl) 180.3 ± 19.90 174.9 ± 16.34 HDL cholesterol (mg/dl) 43.0 ± 3.87 47.26 ± 5.59 0.047* LDL cholesterol (mg/dl) 97.21 ± 20.04 88.68 ± 21.96 0.171 Triglycerides (mg/dl) 115.36 ± 19.15 106.00 ± 12.18 0.141 Serum creatinine (μmol/l) 0.91±13 0.86±10 0.527 Values are mean ± SD; BMI: body mass index, HDL: high-density lipoprotein, LDL: low-density lipoprotein, DAS: disease activity score, DAPSA: disease activity index for psoriatic arthritis. ESR: erythrocyte sedimentation rate, CRP: C-reactive protein. *P-value <0.05.

Table 2. Clinical, inflammatory and vascular measures of the study subjects Variable Psoriatic Arthritis Healthy Controls P value n 22 20   DAS-28 4.03 ± 0.74 - DAPSA 27.2 ± 17.7 ESR (mm 1st hr) 24.64 ± 6.78 16.68 ± 4.54 0.001* CRP (mg/dl) 10.79 ± 7.96 3.93 ± 2.10 0.003* TNF-α (pg/ml) 8.82 ± 4.07 4.07 ± 0.85 IL-6 (pg/ml) 8.77 ± 3.67 4.2 ± 2.83 0.004* IL-1 (pg/ml) 172.9 ± 78.2 90.0 ± 18.9 EPC% 0.028 ± 0.009 0.047 ± 0.006 <0.001* FMD% 7.43 ± 2.12 10.52 ± 0.77 cIMT (mm) 0.65 ± 0.17 0.56 ± 0.09 0.068 Values are mean ± SD; EPC: endothelail progenitor cells, FMD: flow mediated dilatation, cIMT: carotid intima media thickness, TNF-α: tumor necrosis factor-a, IL-6: interleukin-6 and IL-1: : interleukin-1. *P-value <0.05.

Figure. 1 Fluorescence-activated cell sorting (FACS) analysis without the use of a viability marker: the first region (P1) sorts the immature mononuclear cells, the second (P2) identifies CD45 positive cells. The third (P3) identifies CD34 positive cells and the forth (P4) identifies CD133 positive cells. The fifth dotblot gates in quadrant 2 (Q2), identifies the cells positive for CD34 and CD133. Percentage of EPC cells was calculated as double positive cells on dotblot of CD34+ CD133+

Table 3. Correlation analyses between EPC population and disease activity, inflammatory measures and surrogates of vascular function EPC Population Correlation Coefficient   pValue AGE -0.315 0.186 Disease duration -0.166 0.489 BMI -0.331 0.175 ESR -0.245 0.325 CRP -0.657 0.002* DAS-28 -0.633 0.004* DAPSA -0.535 0.021* TNF- α -0.586 0.01* IL-6 -0.641 0.003* IL-1 -0.451 0.058 FMD 0.669 CIMT 0.214 0.388 BMI: body mass index, ESR: erythrocyte sedimentation rate, CRP: C-reactive protein, DAS: disease activity score, DAPSA: disease activity index for psoriatic arthritis. FMD: flow mediated dilatation, cIMT: carotid intima media thickness, TNF-α: tumor necrosis factor-a, IL-6: interleukin-6 and IL-1: interleukin-1. *P-value <0.05  

Fig. 3 Inverse correlation between EPC population and inflammatory measures (CRP & TNF-α)

Fig. 3. EPC % showed significant inverse correlation with disesae activity (DAPSA) and positive correlation with FMD% score

First study to report depleted EPCs in PsA. EPCs correlate with: Disease activity Inflammatory measures (CRP, TNF-α and IL-6) FMD% Suggesting the pivotal role of inflammation in depletion of EPC population. EPC depletion in turn appears to contribute to the enhanced CV risk seen in PsA.

Study Implication…. This study opens many domains of investigation of EPC biology in PsA. The potential role of these cells as surrogate biomarkers of endothelial dysfunction/injury or as potential pathogenic players in PsA should be further investigated. EPCs would possibly also serve as a therapeutic target for preventing cardiovascular risk associated with endothelial dysfunction in PsA.

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