Expression of intracellular cytokines, HSP72, and apoptosis in monocyte subsets during exertional heat stress in trained and untrained individuals

摘要

Normally comprising <10% of all circulating monocytes, the inflammatory subset in the peripheral blood has been shown to expand with exercise (31, 78) and is associated with various inflammatory disorders (29, 30, 82). Elevations in body temperature (32) and secreted levels of TNF-a (71) also have been correlated with inflammatory subset expansion; however, to our knowledge, no data exist relative to exertional heat stress (EHS). Many studies have reported changes in circulating proinflammatory cytokines during EHS (54, 59, 76), and the potential that these mediators originate from circulating leukocytes has been under considerable debate (21, 47, 58, 74-76, 83). Several studies have examined monocytic protein content using a variety of methods including mRNA transcript expression (47, 83) and intracellular flow cytometry (58, 74, 76, 77, 84, 89) in circulating monocytes, without distinction between subsets (21). We recently reported that increases in circulating TNF-a and endotoxin during EHS are accompanied by nuclear factor (NF)-kB translocation in peripheral blood mononuclear cells, suggestive of peripheral blood inflammatory cell activation (68).