Interleukin-1β-Induced Senescence Promotes Osteoblastic Transition of Vascular Smooth Muscle Cells

Interleukin (IL)-1β, as a key biomarker and mediator of vascular calcification in patients with end-stage renal disease (ESRD), may be involved in the process of premature senescence of vascular smooth muscle cells (VSMCs). This work sought to investigate whether IL-1β-induced premature senescence contributes to the process of osteoblastic transition and vascular calcification in VSMCs.

Eighty-eight patients with ESRD (aged 25-81 years), 11 healthy individuals, and 15 cases of lesion-free distal radial arteries from dialysis ESRD patients with angiostomy were collected in this study. Immunohistochemical analysis was performed to detect expression of IL-1β, p21, and bone morphogenetic protein-2 (BMP2) in the distal radial arteries. Primary human VSMCs from healthy neonatal umbilical cords were incubated with test agents for 1-3 days. Intracellular levels of reactive oxygen species (ROS) and senescence-associated-β-galactosidase (SA-β-gal) staining were used to detect senescent cells. Alizarin red staining and the calcium content of the cell layer were used to detect mineral deposition in VSMCs.

Coincident with positive staining of IL-1β, p21, and BMP2 in the lesion-free distal radial arteries, 66.67% patients showed mineral deposition. Serum IL-1β was 0.24 ± 0.57, 1.20 ± 2.95, and 9.41 ± 40.52 pg/mL in 11 healthy individuals, 20 patients without calcification, and 53 patients with calcification, respectively. Analysis of the cross-table chi-square test showed cardiovascular calcification is not correlated with levels of serum IL-1β in patients with ESRD (p = 0.533). In response to IL-1β, VSMCs showed a senescence-like phenotype, such as flat and enlarged morphology, increased expression of p21, an increased activity of SA-β-gal, and increased levels of ROS. IL-1β-induced senescence of VSMCs was required for the activation of IL-1β/NF-κB/p53/p21 signaling pathway. IL-1β-induced senescent VSMCs underwent calcification due to osteoblastic transition mainly depending upon the upregulation of BMP2. Resveratrol, an activator of sirtuin-1, postponed the IL-1β-induced senescence through blocking the NF-κB/p53/p21 pathway and attenuated the osteoblastic transition and calcification in VSMCs.

High levels of IL-1β in medial smooth muscles of arteries may play roles in inducing senescence-associated calcification. IL-1β-induced senescence depending on the activation of the NF-κB/p53/p21 signaling pathway and contributing to osteoblastic transition of VSMCs.