Peripheral blood mononuclear cells from patients with systemic sclerosis spontaneously secrete increased amounts of vascular endothelial growth factor (VEGF) already in the early stage of the disease

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ABSTRACT

Purpose

To investigate the capacity of the peripheral blood mononuclear cells (PBMC) from patients with systemic sclerosis (SSc) to produce vascular endothelial growth factor (VEGF), and to identify clinical associations of altered production of VEGF by PBMC in SSc. In addition, correlation with another pro-angiogenic cytokine, TNF-related weak inducer of apoptosis (TWEAK), was evaluated.

Methods

PBMC were isolated from 25 patients with SSc and 17 healthy controls (HC). VEGF and TWEAK were measured in the supernatants of cultured PBMC using commercially available ELISA kits.

Results

PBMC from SSc patients spontaneously released significantly greater amounts of VEGF as compared with HC. Production of VEGF was comparable between patients with early SSc and those with longer disease duration, and in both SSc groups higher than in HC. Patients without active digital ulcers produced significantly greater amounts of VEGF as compared with HC, while there was no significant difference in the production of VEGF between SSc patients with active digital ulcers and HC. VEGF/TWEAK ratio was significantly higher in PBMC from SSc patients than in HC indicating that high production of VEGF is not paralleled by increased release of TWEAK in SSc.

Conclusions

PBMC form SSc patients produce increased amounts of VEGF already in the early stage of disease. There is an imbalance in the profile of pro-angiogenic mediators produced by PBMC in SSc which might contribute to the pathogenesis of SSc. Further studies should address clinical significance of our findings.

Section snippets

INTRODUCTION

Vascular injury is considered to play a key role in the pathogenesis of systemic sclerosis (scleroderma, SSc) 1, 2. Capillary loss and characteristic deformations of the remaining capillaries are present in nearly all patients with SSc from the very beginning of the disease 3, 4, 5. It has also been shown that the severity of capillary injury correlates with the severity of internal organ involvement 5, 6. Severe ischemia leads to the development of pitting scars and severe digital ulcers.

Patients

25 patients with SSc (21 female and 4 men) were investigated. Patients selected for the study fulfilled the American College of Rheumatology (ACR) classification criteria for SSc.[19] or they had Raynaud's phenomenon and at least one of the following: microangiopathy typical for SSc in capillaroscopy, and/or autoantibodies typical for SSc, which is consistent with the definition of early SSc as proposed by LeRoy and Medsger. [20].

To avoid modification of the activity of leukocytes by

VEGF in SSc patients and healthy controls.

The total leukocyte count, differential leukocyte counts or platelet count did not differ between SSc patients and healthy controls (data not shown). PBMC from SSc patients produced significantly more VEGF (22.6 +/− 10.0 pg/mL/105 cells) compared with PBMC from healthy controls (16.7 +/− 4.0 pg/ mL/105 cells p<0.05 versus SSc patients) (Fig. 1).

The majority (19/25, 76%) of SSc patients had early disease while in the remaining 6 patients disease lasted longer than 3 years in dSSc or longer than

DISCUSSION

In the present study we found that PBMC from SSc patients spontaneously release greater amounts of VEGF as compared with PBMC from healthy subjects. To the best of our knowledge this is the first study evaluating production of VEGF by PBMC from patients with SSc. In general, our findings are consistent with previous studies showing that expression of VEGF is increased in the peripheral blood 8, 9, 10 and skin of patients with SSc 24, 25, 26. Moreover, our results indicate that PBMC might, in

CONCLUSIONS

In conclusion, we showed for the first time that PBMC form SSc patients produce higher amounts of VEGF already in the early stage of disease. Significantly higher VEGF/TWEAK ratio in SSc patients compared with healthy controls indicates that there is an imbalance in the profile of pro-angiogenic mediators produced by PBMC in SSc. Further studies should address clinical significance of our findings.

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      The latter might be of importance in the regeneration of injured blood vessels in SSc since, as discussed above, vascular injury is common and important feature in SSc. Of note, we have previously shown that PBMC from SSc patients release significantly greater amounts of VEGF as compared with healthy controls [38]. Accordingly, injection of PBMC has been shown to improve ischemic diseases through delivery of proangiogenic mediators [39].

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