Biochemical markers cytokines

Osteoclasts are multinucleated cells found on the endosteal surface of bone, in Haversian systems and periosteal surfaces. PTH activates osteoclasts (indirectly via osteoblasts that possess PTH receptors). Calcitonin is a potent inhibitor of osteoclast activity. Local cytokine factors, including interleukin-1 (IL-1), tumour-necrosis factor (TNF), TGF- 0 and interferon-y (INF-y), are important regulators. Osteoclast resorption of bone releases collagen peptides, pyridinoline cross-links and calcium from the bone matrix, through the action of lysosomal enzymes (collagenases and cathepsins). The collagen breakdown products in serum and urine (e.g. hydroxyproline) can be used as biochemical markers. 

Numerous biochemical markers of neuroinflammation have also been found in ALS tissue. The families of compounds include cytokines, chemokines, complement proteins, prostaglandins, interleukins, interferons, integrins, acute phase reactants, apolipoproteins, and (Table 27.1). Many of these biochemical markers have also been found in Alzheimer s disease tissues, suggesting that the inflammatory response in the two conditions may be similar (Eikelenboom and van Gool 2004). 

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