Inflammatory
joint diseases are characterized by enhanced extracellular matrix degradation which is predominantly mediated by
cytokine-stimulated upregulation of
matrix metalloproteinase (
MMP) expression. Besides tumour
necrosis factor-alpha (
TNF-alpha),
Interleukin-1beta (IL-1beta) produced by articular chondrocytes and synovial macrophages, is the most important
cytokine stimulating
MMP expression under inflammatory conditions. Blockade of these two
cytokines and their downstream effectors are suitable molecular targets of antirheumatic
therapy. Hox alpha is a novel stinging nettle (Urtica dioica/Urtica urens) leaf extract used for treatment of
rheumatic diseases. The aim of the present study was to clarify the effects of Hox alpha and the monosubstance
13-HOTrE (13-Hydroxyoctadecatrienic acid) on the expression of
matrix metalloproteinase-1, -3 and -9
proteins (MMP-1, -3, -9). Human chondrocytes were cultured on
collagen type-II-coated petri dishes, exposed to IL-1beta and treated with or without Hox alpha and
13-HOTrE. A close analysis by immunofluorescence microscopy and western blot analysis showed that Hox alpha and
13-HOTrE significantly suppressed IL-1beta-induced expression of
matrix metalloproteinase-1, -3 and -9
proteins on the chondrocytes in vitro. The potential of Hox alpha and
13-HOTrE to suppress the expression of
matrix metalloproteinases may explain the clinical efficacy of stinging nettle leaf extracts in treatment of
rheumatoid arthritis. These results suggest that the monosubstance
13-HOTrE is one of the more active antiinflammatory substances in Hox alpha and that Hox alpha may be a promising remedy for
therapy of inflammatory
joint diseases.