@article {bioinflmu-385,
	title = {{Activation of interleukin-1 signaling cascades in normal and osteoarthritic articular cartilage}},
	journal = {Am J Pathol},
	volume = {171},
	number = {3},
	year = {2007},
	pages = {938-946},
	abstract = {Interleukin (IL)-1 is one of the most important catabolic cytokines
in rheumatoid arthritis. In this study, we were interested in whether we could
identify IL-1 expression and activity within normal and osteoarthritic cartilage.
mRNA expression of IL-1beta and of one of its major target genes, IL-6, was
observed at very low levels in normal cartilage, whereas only a minor
up-regulation of these cytokines was noted in osteoarthritic cartilage,
suggesting that IL-1 signaling is not a major event in osteoarthritis. However,
immunolocalization of central mediators involved in IL-1 signaling pathways
[38-kd protein kinases, phospho (P)-38-kd protein kinases, extracellular
signal-regulated kinase 1/2, P-extracellular signal-regulated kinase 1/2, c-Jun
NH(2)-terminal kinase 1/2, P-c-Jun NH(2)-terminal kinase 1/2, and nuclear factor
kappaB] showed that the four IL-1 signaling cascades are functional in normal and
osteoarthritic articular chondrocytes. In vivo, we found that IL-1 expression and
signaling mechanisms were detectible in the upper zones of normal cartilage,
whereas these observations were more pronounced in the upper portions of
osteoarthritic cartilage. Given these expression and distribution patterns, our
data support two roles for IL-1 in the pathophysiology of articular cartilage.
First, chondrocytes in the upper zone of osteoarthritic articular cartilage seem
to activate catabolic signaling pathways that may be in response to diffusion of
external IL-1 from the synovial fluid. Second, IL-1 seems to be involved in
normal cartilage tissue homeostasis as shown by identification of baseline
expression patterns and signaling cascade activation.},
	doi = {10.2353/ajpath.2007.061083 },
	author = {Z. Fan and S. Soder and S. Oehler and Katrin Fundel and Thomas Aigner}
}