Clinical immunology
Serum in vivo angiogenic activity and some pro-angiogenic cytokine levels in diabetes mellitus type 2 (DM2) patients with or without background retinopathy

In our previous study we observed higher in vivo angiogenic activity and interleukin 18 level in sera of elderly patients with diabetes mellitus type 2 (DM2) and background retinopathy, in comparison to the controls.
The aim of the present study was to compare the serum IGF1, IL-18, and VEGF concentration as well as serum in vivo angiogenic activity in the diabetes mellitus type 2 (DM2) patients with (DM2R+) or without (DM2R-) background retinopathy and healthy controls. Moreover, the influence of human IGF1 on the angiogenic activity of sera obtained from healthy people and DM2 patients, and on the angiogenic activity of recombined human VEGF and IL-18 was estimated. Insulin-like growth factor 1 (IGF1) is described as partially responsible for diabetic retinopathy and renal vascular complications. However, its possible role in the negative regulation of angiogenesis in some selected physiological conditions has been mentioned as well.
Evaluation of angiogenic response was performed 3 days after intradermal injection of tested materials into mice skin (serum – or cytokine – induced angiogenesis, SIA, or CIA test). Estimation of VEGF, IL-18 and IGF 1 levels in tested sera were performed by ELISA.
Both DM2 groups presented higher angiogenic activity than that observed in the controls (p<0.01). IL-18 level was higher in DM2R+ group than in DM2R- group and than in the respective control (p<0.05). No differences in VEGF and IGF1 levels were seen. The addition of IGF1 to the sera of both DM2 patients and controls highly significantly diminished their angiogenic activity. Similarly, the new blood vessels formation stimulated by VEGF or IL-18 in the CIA test, was significantly lower in the presence of IGF1 (p<0.01).
Conclusions: a) in DM2 patients, serum IL-18 may serve as a marker of retinopathy appearance, b) in neovascular reaction evoked in vivo in mice skin after injection of human serum or human IL-18 and VEGF, human IGF1 behaved as angiogenesis inhibitor.