IL-1ß/MMP9 activation in primary human vascular smooth muscle-like cells: Exploring the role of TNFα and P2X7.

BACKGROUND: Vascular smooth muscle cells exhibit phenotypic plasticity in response to microenvironmental stimuli and contribute to vascular remodelling through mechanisms only partially understood. In atherosclerosis, P2X-purinoceptor7 (P2X7) has been related to interleukin-1ß (IL-1ß) and metalloproteinase 9 (MMP9). The hypoxia-inducible factor-1alpha (HIF1α) was associated to remodelling. Here the activation of IL-1ß and MMP9 was studied in relationship to P2X7 and HIF1α in cells exploited from human carotid plaque and internal mammary artery. METHODS AND RESULTS: Migrating cells expressed HIF1α-regulated canopy FGF-signalling regulator 2 and CD117, and led to primary cells with SMC-like phenotype (VSMC), P2X7+. We investigated in VSMC the effects of hypoxia, of treatment with tumour necrosis factor-α (TNFα) and/or with P2X7 antagonist, A740003. Quantitative RT-PCR showed that hypoxia unaffected IL-1ß and down-regulated MMP9 mRNAs, without activating HIF1α. TNFα increased IL-1ß mRNA via NLR Family Pyrin Domain-Containing 3, with production of proIL-1ß but no rise of mature IL-1ß. Zymography demonstrated that A740003 triggered MMP9 secretion from VSMC. Combination of A740003 with TNFα abrogated this effect. Combination was ineffective on IL-1ß activation elicited by TNFα, but down-regulated HIF1α mRNA. A740003 induced the intracellular P2X7 aggregation and differently perturbed lysosome and mitochondria network compared to TNFα. CONCLUSIONS: Cells migration from human arteries leads to partially differentiated VSMC analogous to neointimal cells within atherosclerotic lesions. Down-regulated HIF1α in stimulated VSMC translates in resilience in atherosclerotic lesions. P2X7-independent partial activation of IL-1ß elicited by TNFα underlines complexity of the cytokine secretion. Data also supported P2X7 as modulator of MMP9 secretion, important for atherosclerosis progression.