Chemokines
Chemokines are promiscuous in that they can bind several G-protein-coupled receptors and function either as homeostatic or chemotactic proteins (Martins-Green et al., 2013). There are four classes of chemokines: CC chemokines, CXC chemokines, C chemokines, and CX3C chemokines.
The chemokine CXCL8 (IL-8) is particularly important for neutrophil chemotaxis. It is produced by many cell types (e.g. neutrophils, macrophages, keratinocytes, airway smooth muscle cells, endothelial cells). It induces chemotaxis and phagocytosis by neutrophils and is pro-angiogenic (Baggiolini & Clark-Lewis, 1992).Mesenchymal growth factors
Mesenchymal growth factors are cytokines that are extremely important for hematopoiesis. Erythropoietin, thrombopoietin, and colony-stimulating factors are included in this category of cytokines.
Tumor necrosis factors
The most well-characterized member of the TNF family of cytokines is TNFα. This protein induces apoptosis in some cells it interacts with, while other cells are stimulated to proliferate and differentiate. TNFα is a potent stimulator of acute phase protein production by the liver. It is associated with fever via the stimulation of IL-1 secretion and cachexia associated with chronic inflammatory diseases. TNFs induce endothelial cell dysfunction, leading to thrombosis, inflammation, and increased vascular permeability (Zhang et al., 2009). They also stimulate leukocyte functions.