Cyclic strain stimulates monocyte chemotactic protein-1 mRNA expression in smooth muscle cells

The Entry and Egress of Monocytes in Atherosclerosis: A Biochemical and Biomechanical Driven Process

In accordance with “the response to injury” theory, the entry of monocytes into the intima guided by inflammation signals, taking up cholesterol and transforming into foam cells, and egress from plaques determines the progression of atherosclerosis. Multiple cytokines and receptors have been reported to be involved in monocyte recruitment such as CCL2/CCR2, CCL5/CCR5, and CX3CL1/CX3CR1, and the egress of macrophages from the plaque like CCR7/CCL19/CCL21. Interestingly, some neural guidance molecules such as Netrin-1 and Semaphorin 3E have been demonstrated to show an inhibitory effect on monocyte migration. During the processes of monocytes recruitment and migration, factors affecting the biomechanical properties (e.g., the membrane fluidity, the deformability, and stiffness) of the monocytes, like cholesterol, amyloid-β peptide (Aβ), and lipopolysaccharides (LPS), as well as the biomechanical environment that the monocytes are exposed, like the extracellular matrix stiffness, mechanical stretch, blood flow, and hypertension, were discussed in the latter section. Till now, several small interfering RNAs (siRNAs), monoclonal antibodies, and antagonists for CCR2 have been designed and shown promising efficiency on atherosclerosis therapy. Seeking more possible biochemical factors that are chemotactic or can affect the biomechanical properties of monocytes, and uncovering the underlying mechanism, will be helpful in future studies.

Atheromas feel the pressure: biomechanical stress and atherosclerosis

Atherosclerosis, a chronic vascular disease, is the underlying cause of over half the deaths in the United States each year. Variations in local vascular hemodynamics predispose select sites in the vasculature to atherosclerosis, and the atherosclerotic lesions, in turn alter the biomechanical functioning of the local microenvironment, the consequences of which are not well understood on a molecular level. Further progress in the field of atherosclerosis will require an understanding of the relationship between biomechanics, the tissue microenvironment, and the cellular and molecular response to these factors. This review summarizes this field, particularly within the context of the vascular smooth muscle cell.

Biomechanical stress induces novel arterial intima-enriched genes: implications for vascular adaptation to stress

BACKGROUND

The arterial vasculature is subjected to considerably greater biomechanical stress than the venous circulation. This is reflected in the difference in morphology between large arteries and veins, however little is known about the molecular differences that arise as a consequence of biomechanical stress. Previously, we identified a group of arterial intima-enriched (AIE) genes: sciellin, periplakin, SPRR3, envoplakin, galectin 7, and plakoglobin that are functionally related in that they contribute to the stress properties of stratified epithelium. We sought to test our hypothesis that these genes were regulated by biomechanical stress in vascular smooth muscle cells (VSMCs).

METHODS

Immunofluorescence was employed to determine the expression of the AIE genes in saphenous vein coronary artery bypass grafts. Furthermore, we used a model of cyclic stress to determine if the AIE genes were regulated by biomechanical stress in VSMCs in vitro.

RESULTS

Sciellin and periplakin were upregulated in saphenous vein coronary artery bypass grafts after arterialization, but were absent in non-arterialized saphenous veins. Sciellin, SPRR3, and periplakin transcripts were all upregulated (4.67-, 4.95-, 2.77-fold, respectively) by prolonged exposure to cyclic strain (24-72 h), but not at earlier time points.

CONCLUSIONS

These findings suggest a novel role for several human AIE genes in the VSMC response to arterialization and extended cyclic strain.

SUMMARY

Biomechanical stress has long been implicated in vascular pathologies. We report the novel finding of a group of genes, previously studied in stratified epithelium, that were regulated by prolonged cyclic stress in vascular smooth muscle cells. This may have important implications to vascular disease.