Cytokines are a group of peptides or small proteins that are involved in intercellular communication. Most of them are involved in local processes but some have endocrine activity. Cytokines are produced mainly by lymphocytes, monocytes, granulocytes, but also by fibroblasts, endothelial and epithelial cells. Disturbances of the integrity of tissues are the main inducers of cytokine synthesis connected with local immune response. On the other hand there is the group of constitutively produced cytokines that regulates the processes of hematopoesis, tissue remodeling, and lymphocytes migration. At present over one hundred biologically active substances described as cytokines have been identified. High levels of TNF-α, IL-1β i IL-6 are demonstrated both in severe cardiac insufficiency with cachexia and in the left sided cardiac failure. It has been established in several studies that proinflamatory cytokines contribute to dilated cardiomiopathy involvement, decreased blood perfusion in skeletal muscles, and exert endothelial injury of vessels, develop cachexia and inappetance and stimulate cardiac myocytes apoptosis. It was confirmed that cardiac myocytes are able to synthetize TNF-α in response to different types of overload, e.g. volume overload, pressure or ischemic (post infarct). TNF-α and IL-2 impart a negative inotropic effect on the heart proportional to their concentration. TNF-α, IL-1 and IL-6 regulate cardiac functioning indirectly due to the activity of the following: nitric oxide, reactive oxygen species, sphingolipid mediators, arachidonic acid and the modulation of β-adrenergic response.
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