Exacerbated vein graft arteriosclerosis in protein kinase Cδ–null mice

Abstract

Smooth muscle cell (SMC) accumulation is a key event in the development of atherosclerosis, including vein bypass graft arteriosclerosis. Because members of the protein kinase C (PKC) family signal cells to undergo proliferation, differentiation, or apoptosis, we generated PKCdelta knockout mice and performed vein bypass grafts on these animals. PKCdelta(-/-) mice developed normally and were fertile. Vein segments from PKCdelta(-/-) mice isografted to carotid arteries of recipient mice of either genotype led to a more severe arteriosclerosis than was seen with PKCdelta(+/+) vein grafts. Arteriosclerotic lesions in PKCdelta(-/-) mice showed a significantly higher number of SMCs than were found in wild-type animals; this was correlated with decreased SMC death in lesions of PKCdelta(-/-) mice. SMCs derived from PKCdelta(-/-) aortae were resistant to cell death induced by any of several stimuli, but they were similar to wild-type SMCs with respect to mitogen-stimulated cell proliferation in vitro. Furthermore, pro-apoptotic treatments led to diminished caspase-3 activation, poly(ADP-ribose) polymerase cleavage, and cytochrome c release in PKCdelta(-/-) relative to wild-type SMCs, suggesting that their apoptotic resistance involves the loss of free radical generation and mitochondrial dysfunction in response to stress stimuli. Our data indicate that PKCdelta maintains SMC homeostasis and that its function in the vessel wall per se is crucial in the development of vein graft arteriosclerosis.

Transgenic Overexpression of IL-37 Protects Against Atherosclerosis and Strengthens Plaque Stability

“…Meanwhile, to further verify that IL-37 suppresses SMC apoptosis, we next pretreated HASMCs with exogenous IL-37 or silenced endogenous IL-37 using IL-37 small interfering RNA (siRNA; siIL-37) before we administered positive stimulation. The HASMCs were then cultured with or without hydrogen peroxide (H 2 O 2 ) or the pro-inflammatory cytokines IFN-γ and TNF-α, which are potent inducers of apoptosis [27]. As expected, flow cytometric analysis showed that treatment with H 2 O 2 or IFN-γ and TNF-α increased the frequency of apoptotic SMCs.…”

“…Cell apoptosis was monitored using FACS analysis with a Flow cytometric apoptosis analysis Kit (eBioscience, Annexin V-FITC and Propidium Iodide staining) [27]. …”

Transcription factor and kinase-mediated signaling in atherosclerosis and vascular injury

“…These studies also showed that PKCβII was involved in vascular smooth muscle cell activation in part through ERK and EGR-1 [59]. Leitges et al [60] showed that PKC δ-null mice showed reduced arteriosclerosis as compared with the wild-type littermates in a vein graft model. The mechanisms responsible for this are unclear because vascular smooth muscle cells from aortas of PKCδ -/-mice were significantly more resistant to apoptosis (induced by multiple stimuli) compared with controls, whereas mitogenic potential was unchanged [60].…”

“…Leitges et al [60] showed that PKC δ-null mice showed reduced arteriosclerosis as compared with the wild-type littermates in a vein graft model. The mechanisms responsible for this are unclear because vascular smooth muscle cells from aortas of PKCδ -/-mice were significantly more resistant to apoptosis (induced by multiple stimuli) compared with controls, whereas mitogenic potential was unchanged [60]. Generation of tissue-specific PKC knockout models will be important in furthering our understanding of the role of PKC in vascular disease [61] and broadening our focus to include inflammatory cells as well as endothelial and smooth muscle cells.…”

Experimental Vein Graft Research: A Critical Appraisal of Models

“…To complicate this issue, the experimental literature has been diluted with an interchanging of terms, often substituting atherosclerotic terminology for what is more identifiable as neointimal formation, either without an atherogenic stimulus 42 or with superimposed atherogenesis. 51,52 This confusion in the literature is a major obstacle to understanding the fundamental mechanisms underlying vein graft pathologies. A better appreciation of the distinction between these pathologies would use the stable development of neointima that then progresses to atherosclerotic lesion presence, ideally with a substantial stenotic component.…”