Objective and design
Evaluating the pro-/anti-inflammatory activity of the C-terminal cleavage product of osteopontin in comparison to angiotensin 1–7.
Material and subjects
Human coronary endothelial cells (hcEC) treated with conditioned media from human U937 macrophages.
Treatment
Macrophages were (pre)treated with C-terminal, full-length or N-terminal osteopontin (OPN-C, OPN-FL, OPN-N, respectively), angiotensin II, angiotensin 1–7 or TNF-α. OPN-C modulatory capacity was compared to that of Ang1–7 in inhibiting subsequent Ag II, OPN-FL or OPN-N-induced macrophage-mediated endothelial inflammation.
Methods
Protein expression of NFκB, IκB, vCAM-1 and iCAM-1 was assessed using western blot. Promotor activation by NFκB was also assessed by dual-luciferase reporter assay.
Results
Conditioned media of macrophages treated with OPN-C induced hcECs’ NfκB activation to a lower degree than OPN-FL or OPN-N. Priming of macrophages with angiotensin 1–7 attenuated the endothelial pro-inflammatory effect induced by subsequent exposure of the macrophages to angiotensin II, OPN-FL or OPN-N. This was evidenced by both NfκB activation and vCAM and iCAM expression. In contrast, priming macrophages with OPN-C did not significantly attenuate the subsequent response to the pro-inflammatory cytokines.
Conclusions
OPN-C induces lower macrophage-induced endothelial inflammation compared to OPN-FL or OPN-N, but unlike angiotensin 1–7, fails to prevent endothelial inflammation induced by subsequent pro-inflammatory macrophage stimulation.