IL-11 (Interleukin 11) is a pleiotropic cytokine in the IL-6 family, which also includes LIF, CNTF, Oncostatin M, Cardiotrophin-1, IL-27 and IL-31 [1-4]. In humans, IL-11 was also independently discovered as an adipogenesis inhibitory factor (AGIF) [3]. The mouse IL-11 cDNA encodes a 199 amino acid (aa) precursor, which generates a 178 aa, 19 kDa mature unglycosylated protein. Mature mouse IL-11 shares 88%, 97%, and 89% aa sequence identity with human, rat and canine IL-11, respectively. IL-11 is secreted by osteoblasts, synoviocytes, fibroblasts, chondrocytes, intestinal myofibroblasts, and trophoblasts, among other cell types [1]. It is found in the plasma mainly during inflammation, such as that associated with viral infection, cancer, or inflammatory arthritis, and is considered to be primarily anti-inflammatory [1]. It stimulates hematopoiesis and thrombopoiesis, regulates macrophage differentiation, and confers mucosal protection in the intestine [1]. It has also been found to enhance T cell polarization toward Th2, promote B cell IgG production, increase osteoclast bone absorption, protect endothelial cells from oxidative stress, and regulate epithelial proliferation and apoptosis [1]. IL-11 synergizes with several other cytokines to produce these effects, and its effects overlap with those of IL-6 [1]. IL-11 receptor activation requires formation of a complex of two IL-11 molecules with two molecules of the ligand-binding IL-11 R alpha subunit and two molecules of the ubiquitously expressed cell signaling beta subunit, gp130 [5].
Reference
[1] Putoczki, T. and M. Ernst (2010) J. Leukoc. Biol. 88:1109.
[2] Paul, S.R. et al. (1990) Proc. Natl. Acad. Sci. USA 87:7512.
[3] Kawashima, I. et al. (1991) FEBS Lett. 283:199.
[4] Morris, J.C. et al. (1996) Exp. Hematol. 24:1369.
[5] Barton, V.A. et al. (2000) J. Biol. Chem. 275:36197.
[6] Curtis, D.J. et al. (1997) Blood 90:4403.
[7] Baumann, H. et al. (1996) J. Immunol. 157:284.
[8]- Karow, J. et al. (1996) Biochem. J. 318:489.