Comparative effects of 2 antioxidants, selenomethionine and epigallocatechin-gallate, on catabolic and anabolic gene expression of articular chondrocytes.
OBJECTIVE
. To determine the effects of selenomethionine (Se-met) and epigallocatechin-gallate (EGCg) on gene expression, activation of mitogen-activating kinases, and DNA binding of nuclear factor-kappaB (NF-kappaB) and apolipoprotein-1 (AP-1) in articular chondrocytes.


METHODS
Chondrocytes, cultured in low-oxygen tension, were pretreated with L-selenomethionine or EGCg for 24 h, followed by interleukin 1 (IL-1beta) for 1 h (nuclear and cytoplasmic extracts) or 24 h (RNA extraction). Reverse transcription-polymerase chain reaction was performed to determine mRNA levels of matrix metalloproteinases (MMP-1, -3, -13), aggrecanases (-1, -2), IL-1beta, inducible nitric oxide synthase, cyclooxygenases (-1, -2), type II collagen and aggrecan, and transforming growth factor-beta (TGF-beta1, -2, -3) and their receptors I and II. Activity of mitogen-activating protein kinases (MAPK) was assayed by Western blot and AP-1/NF-kB DNA binding by electrophoretic mobility shift assay.


RESULTS
Pretreatment with 0.5 microM Se-met prevented IL-1beta-induced MMP-1 and aggrecanase-1 expression, and reduced the cytokine inhibitory effect on type II collagen, aggrecan core protein, and TGF-beta receptor II (TGF-betaRII) mRNA levels. EGCg was more efficient in modulating the effects of IL-1beta on the genes studied. Whereas EGCg inhibited the IL-1beta-activated MAPK, NF-kappaB, and AP-1, Se-met stimulated that signaling pathway. This could account for the differential effects exerted by these antioxidants on chondrocytes.


CONCLUSIONS
Our data provide insights into the mechanisms whereby ECGg and selenium modulate chondrocyte metabolism. Despite their differential mechanisms of action, the 2 compounds may exert global beneficial effects on articular cartilage.
Andriamanalijaona
Rina
R
Laboratory of Connective Tissue Biochemistry, Faculty of Medicine, 14032 Caen Cedex, France.
Kypriotou
Madeleine
M
Baugé
Catherine
C
Renard
Emmanuelle
E
Legendre
Florence
F
Raoudi
Maha
M
Boumediene
Karim
K
Gatto
Hugues
H
Monginoux
Patricia
P
Pujol
Jean-Pierre
JP
D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D002358:Cartilage, Articular / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology; D002417:Cattle; D002478:Cells, Cultured; D019902:Chondrocytes / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology; D004247:DNA / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D004798:Enzymes / Q000235:genetics* / Q000378:metabolism; D005109:Extracellular Matrix / Q000187:drug effects / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects*; D007375:Interleukin-1 / Q000494:pharmacology; D016328:NF-kappa B / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012645:Selenomethionine / Q000494:pharmacology*; D018808:Transcription Factor AP-1 / Q000378:metabolism
D000975:Antioxidants; D004798:Enzymes; D007375:Interleukin-1; D016328:NF-kappa B; D012333:RNA, Messenger; D018808:Transcription Factor AP-1; D002392:Catechin; D004247:DNA; D012645:Selenomethionine; C045651:epigallocatechin gallate