The Extracellular Matrix and Cell Walls

During inflammation, degranulation of immune cells releases serine proteases that pass through and bind to the capillary wall. Increased levels of Bik suppress these immune cell proteases and protect the extracellular matrix in arterial walls and connective tissue [4]. Bik inhibits phagocytic destruction of cells. Bik has been shown to inhibit elastases, granzymes A and K [4, 57], Mast cell tryptases (J3- and a-tetrameric forms with a molecular weight of 134 kDa) are resistant to aprotinin [58]. Lymphocytes serine esterase TL2 is not inhibited by Bik [59]. 

The extracellular matrix of vascular wall cells, a complex array of collagen, elastin, adhesion proteins, and proteoglycans (see Chapter 13), mediates a variety of functions with significance for the development of atherosclerosis and cardiovascular disease. These include blood cell adhesion, lipoprotein binding, vascular wall... 

Atherosclerotic lesions are thought to arise from transport and retention of plasma LDL through the endothelial cell layer into the extracellular matrix of the subendothelial space. Once in the artery wall, LDL is chemically modified through oxidation and nonenzymatic glycation. Mildly oxidized LDL then recruits monocytes into the artery wall. These monocytes then become transformed into macrophages that accelerate LDL oxidation. 

Vardi A, Formiggini F, Casotti R, De Martino A, Ribalet F, Miralto A, Bowler C (2006) A stress surveillance system based on calcium and nitric oxide in marine diatoms. PLoS Biol 4 411 119 Vorwerk S, Somerville S, Somerville C (2004) The role of plant cell wall polysaccharide composition in disease resistance. Trends Plant Sci 9 203-209 Vreeland V, Laetsch WM (1990) A gelling carbohydrate in algal cell wall formation. In Adair WS, Mecham RP (eds) Organization and assembly of plant and animal extracellular matrix. Academic, San Diego, CA, ppl 37—171... 

These cells, located in the medial layer of the vessel wall, are normally relatively nonproliferative, but they secrete proteins which make up the extracellular matrix of the vessel wall. However, the narrowing of the arteries, a critical, often fatal, consequence of atherosclerosis is due to proliferation of VSMC and their migration into the intimal layer of the vessel wall. 

Polymeric carbohydrates are major structural components in plant and bacterial cell walls and in the extracellular matrix of vertebrates. Branched-chain polymeric carbohydrates covalently linked to proteins are used to give proteins unique signatures that guide them to their final destination and that facilitate specific interactions between free proteins or proteins attached to cells. 

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