Abstract 16886: Caspase-4/11 Mediates Intima Formation by Increasing Inflammation and Smooth Muscle Cell Migration and Proliferation

Abstract

Introduction: Intima formation after vessel injury occurs via vascular smooth muscle cell(VSMC) proliferation, migration, dedifferentiation and inflammatory response. Recently, it was demonstrated that caspase-4 (Casp4, human)/caspase11(Casp11, mouse) increases the synthesis and release of inflammatory factors in macrophages, indicating a potential role of Casp4/Casp11 in intima formation. However, to date, the biological role of Casp4/Casp11 in vivo has not been investigated. Therefore, we hypothesize that Casp4/Casp11 deficiency will inhibit intima formation. Method and Results: We measured Casp4 expression and location by immunohistochemistry (IHC) staining in human coronary artery intima lesions from coronary artery disease patients. Surprisingly, we found Casp4 expression was remarkably increased in smooth muscle cells (SMC) and macrophages. We observed similar phenomena of Casp11 expression and location in intima of complete carotid ligation mouse model. These findings imply an important role of Casp4/11 in SMC function. Thus, we performed complete carotid ligation on Casp11 wild type (WT) and knockout (KO) mice.Morphometric analysis demonstrated that Casp11 depletion robustly attenuated intima area and intima/media ratio (I/M) compared with WT mice . Inflammation was quantified by CD45 IHC staining . SMC proliferation was detected by PCNA staining and there was a marked decrease of PCNA positive SMCs. In vitro, Casp4 expression was time- and dose-dependently increased by platelet-derived growth factor(PDGF), angiotensin II(AngII) and TNF-α in human coronary artery SMCs(HCASMCs). Depletion of Casp4 by siRNA decreased expression of cytokines, e.g. IL-1α, IL-1β, IL-6, as well as protein expression of adhesion factors (VCAM-1, ICAM-1, MCP-1) induced by PDGF, AngII or TNF-α. Moreover, HCASMC proliferation stimulated by PDGF was measured by EdU cell proliferation assay and was inhibited by 65% after knockdown of Casp4. Wound scratch assay demonstrated impaired HCASMC migration in Casp4 depleted cells. However, Casp4 has no effects on HCASMCs dedifferentiation. Mechanistically, Casp4 knockdown significantly inhibited NF-κB signaling. Conclusions: Casp4/11 promotes intima formation by increasing SMC proliferation, migration and inflammation through NF κB signaling. Specific inhibition of the Casp4/11 will provide novel therapeutic strategy for vascular remodeling related diseases.