Pharmacologic Inhibition of Tpl2 Blocks Inflammatory Responses in Primary Human Monocytes, Synoviocytes, and Blood

Abstract

Tumor necrosis factor α (TNFα) is a pro-inflammatory cytokine that controls the initiation and progression of inflammatory diseases such as rheumatoid arthritis. Tpl2 is a MAPKKK in the MAPK (i.e. ERK) pathway, and the Tpl2-MEK-ERK signaling pathway is activated by the pro-inflammatory mediators TNFα, interleukin (IL)-1β, and bacterial endotoxin (lipopolysaccharide (LPS)). Moreover, Tpl2 is required for TNFα expression. Thus, pharmacologic inhibition of Tpl2 should be a valid approach to therapeutic intervention in the pathogenesis of rheumatoid arthritis and other inflammatory diseases in humans. We have developed a series of highly selective and potent Tpl2 inhibitors, and in the present study we have used these inhibitors to demonstrate that the catalytic activity of Tpl2 is required for the LPS-induced activation of MEK and ERK in primary human monocytes. These inhibitors selectively target Tpl2 in these cells, and they block LPS- and IL-1β-induced TNFα production in both primary human monocytes and human blood. In rheumatoid arthritis fibroblast-like synoviocytes these inhibitors block ERK activation, cyclooxygenase-2 expression, and the production of IL-6, IL-8, and prostaglandin E2, and the matrix metalloproteinases MMP-1 and MMP-3. Taken together, our results show that inhibition of Tpl2 in primary human cell types can decrease the production of TNFα and other pro-inflammatory mediators during inflammatory events, and they further support the notion that Tpl2 is an appropriate therapeutic target for rheumatoid arthritis and other human inflammatory diseases. Tumor necrosis factor α (TNFα) is a pro-inflammatory cytokine that controls the initiation and progression of inflammatory diseases such as rheumatoid arthritis. Tpl2 is a MAPKKK in the MAPK (i.e. ERK) pathway, and the Tpl2-MEK-ERK signaling pathway is activated by the pro-inflammatory mediators TNFα, interleukin (IL)-1β, and bacterial endotoxin (lipopolysaccharide (LPS)). Moreover, Tpl2 is required for TNFα expression. Thus, pharmacologic inhibition of Tpl2 should be a valid approach to therapeutic intervention in the pathogenesis of rheumatoid arthritis and other inflammatory diseases in humans. We have developed a series of highly selective and potent Tpl2 inhibitors, and in the present study we have used these inhibitors to demonstrate that the catalytic activity of Tpl2 is required for the LPS-induced activation of MEK and ERK in primary human monocytes. These inhibitors selectively target Tpl2 in these cells, and they block LPS- and IL-1β-induced TNFα production in both primary human monocytes and human blood. In rheumatoid arthritis fibroblast-like synoviocytes these inhibitors block ERK activation, cyclooxygenase-2 expression, and the production of IL-6, IL-8, and prostaglandin E2, and the matrix metalloproteinases MMP-1 and MMP-3. Taken together, our results show that inhibition of Tpl2 in primary human cell types can decrease the production of TNFα and other pro-inflammatory mediators during inflammatory events, and they further support the notion that Tpl2 is an appropriate therapeutic target for rheumatoid arthritis and other human inflammatory diseases. Tpl2 is a member of the MAPKKK family of serine/threonine kinases. It resides upstream of the MAPKKs MEK1 and MEK2, and, in turn, the MAPKs ERK1 and ERK2. This Tpl2-MEK-ERK signaling module is activated in response to various pro-inflammatory stimuli, and it regulates the expression of several pro-inflammatory mediators (1Das S. Cho J. Lambertz I. Kelliher M.A. Eliopoulos A.G. Du K. Tsichlis P.N. J. Biol. Chem. 2005; 280: 23748-23757Abstract Full Text Full Text PDF PubMed Scopus (121) Google Scholar, 2Dumitru C.D. Ceci J.D. Tsatsanis C. Kontoyiannis D. Stamatakis K. Lin J.H. Patriotis C. Jenkins N.A. Copeland N.G. Kollias G. Tsichlis P.N. Cell. 2000; 103: 1071-1083Abstract Full Text Full Text PDF PubMed Scopus (705) Google Scholar, 3Eliopoulos A.G. Dumitru C.D. Wang C.C. Cho J. Tsichlis P.N. EMBO J. 2002; 21: 4831-4840Crossref PubMed Scopus (233) Google Scholar, 4Eliopoulos A.G. Wang C.C. Dumitru C.D. Tsichlis P.N. EMBO J. 2003; 22: 3855-3864Crossref PubMed Scopus (138) Google Scholar, 5Kontoyiannis D. Boulougouris G. Manoloukos M. Armaka M. Apostolaki M. Pizarro T. Kotlyarov A. Forster I. Flavell R. Gaestel M. Tsichlis P. Cominelli F. Kollias G. J. Exp. Med. 2002; 196: 1563-1574Crossref PubMed Scopus (219) Google Scholar, 6Rodriguez C. Pozo M. Nieto E. Fernandez M. Alemany S. Cell Signal. 2006; 18: 1376-1385Crossref PubMed Scopus (19) Google Scholar, 7Stafford M.J. Morrice N.A. Peggie M.W. Cohen P. FEBS Lett. 2006; 580: 4010-4014Crossref PubMed Scopus (37) Google Scholar, 8Sugimoto K. Ohata M. Miyoshi J. Ishizaki H. Tsuboi N. Masuda A. Yoshikai Y. Takamoto M. Sugane K. Matsuo S. Shimada Y. Matsuguchi T. J. Clin. Investig. 2004; 114: 857-866Crossref PubMed Scopus (70) Google Scholar). Notably, Tpl2 regulates the expression of TNFα protein, which is critical to the initiation and progression of many inflammatory disorders including rheumatoid arthritis (9Choy E.H. Panayi G.S. N. Engl. J. Med. 2001; 344: 907-916Crossref PubMed Scopus (1927) Google Scholar, 10Aggarwal B.B. Samanta A. Feldmann M. Oppenheim J.J. Feldmann M Cytokine Reference: A Compendium of Cytokines and Other Mediators of Host Defense. 1st Ed. Academic Press, San Diego2001: 413-434Google Scholar, 11Feldmann M. Maini R.N. Annu. Rev. Immunol. 2001; 19: 163-196Crossref PubMed Scopus (1155) Google Scholar, 12Schottelius A.J. Moldawer L.L. Dinarello C.A. Asadullah K. Sterry W. Edwards 3rd, C.K. Exp. Dermatol. 2004; 13: 193-222Crossref PubMed Scopus (164) Google Scholar, 13Simmons D.L. Drug Discov. Today. 2006; 11: 210-219Crossref PubMed Scopus (63) Google Scholar). Rheumatoid arthritis occurs in nearly 1% of the adult population in most western countries, with an annual incidence of ∼0.04%, and it can develop into a chronic, debilitating condition characterized by joint pain/swelling/stiffness, restricted mobility, and the erosion of bone and cartilage in affected joints (14Doran M.F. Pond G.R. Crowson C.S. O'Fallon W.M. Gabriel S.E. Arthritis Rheum. 2002; 46: 625-631Crossref PubMed Scopus (377) Google Scholar). Protein therapeutics such as ENBREL® (etanercept) (soluble TNFRII-Fc), and REMICADE® (infliximab) and HUMIRA® (adalimumab) (anti-tumor necrosis factor α antibodies) (TNFα) 3The abbreviations used are: TNF, tumor necrosis factor; CaMKII, calciumcalmodulin-dependent protein kinase II; CMV, cytomegalovirus; COX, cyclooxygenase; DELFIA, dissociation-enhanced lanthanide fluoroimmunoassay; DMEM, Dulbeccoʼns modified Eagleʼns media; EGFR, epidermal growth factor receptor; ELISA, enzyme-linked immunosorbent assay; ERK, extracellular signal-regulated kinase; FBS, fetal bovine serum; GST, glutathione S-transferase; IC50, drug concentration required for 50% inhibition; IκBα, inhibitor of NF-κB; IKK, inhibitor of NF-κB kinase; IL, interleukin; JNK, c-Jun N-terminal kinase; KC, cytokine-induced neutrophil chemoattractant; LPS, lipopolysaccharide; MAPK, mitogen-activated protein kinase; MCP, monocyte chemoattractant protein; MEK, mitogen-activated protein/ERK kinase; MK2, MAPK-activated protein kinase-2; MKK, mitogen-activated protein kinase kinase; MMP, matrix metalloproteinase; NF-κB, nuclear factor-κB; PG, prostaglandin; PGE2, protein kinase protein kinase rheumatoid arthritis fibroblast-like activation, and tumor necrosis factor receptor; kinase; that and TNFα have and they have of these the of for and inflammatory and they have the for inhibitors with of to in cytokine signaling and in the production of TNFα, a highly inhibitor of Tpl2 should an for inflammatory disorders such as rheumatoid arthritis. with have that Tpl2 is required for the expression of TNFα in the of in and TNFα production C.D. Ceci J.D. Tsatsanis C. Kontoyiannis D. Stamatakis K. Lin J.H. Patriotis C. Jenkins N.A. Copeland N.G. Kollias G. Tsichlis P.N. Cell. 2000; 103: 1071-1083Abstract Full Text Full Text PDF PubMed Scopus (705) Google Scholar, 8Sugimoto K. Ohata M. Miyoshi J. Ishizaki H. Tsuboi N. Masuda A. Yoshikai Y. Takamoto M. Sugane K. Matsuo S. Shimada Y. Matsuguchi T. J. Clin. Investig. 2004; 114: 857-866Crossref PubMed Scopus (70) Google Scholar). In a restricted in ERK activation, with signaling the and MAPK C.D. Ceci J.D. Tsatsanis C. Kontoyiannis D. Stamatakis K. Lin J.H. Patriotis C. Jenkins N.A. Copeland N.G. Kollias G. Tsichlis P.N. Cell. 2000; 103: 1071-1083Abstract Full Text Full Text PDF PubMed Scopus (705) Google Scholar, 8Sugimoto K. Ohata M. Miyoshi J. Ishizaki H. Tsuboi N. Masuda A. Yoshikai Y. Takamoto M. Sugane K. Matsuo S. Shimada Y. Matsuguchi T. J. Clin. Investig. 2004; 114: 857-866Crossref PubMed Scopus (70) Google Scholar). a progression of in a of inflammatory and ERK activation in (1Das S. Cho J. Lambertz I. Kelliher M.A. Eliopoulos A.G. Du K. Tsichlis P.N. J. Biol. Chem. 2005; 280: 23748-23757Abstract Full Text Full Text PDF PubMed Scopus (121) Google Scholar, 4Eliopoulos A.G. Wang C.C. Dumitru C.D. Tsichlis P.N. EMBO J. 2003; 22: 3855-3864Crossref PubMed Scopus (138) Google Scholar, 5Kontoyiannis D. Boulougouris G. Manoloukos M. Armaka M. Apostolaki M. Pizarro T. Kotlyarov A. Forster I. Flavell R. Gaestel M. Tsichlis P. Cominelli F. Kollias G. J. Exp. Med. 2002; 196: 1563-1574Crossref PubMed Scopus (219) Google Scholar). These the Tpl2-MEK-ERK module as a signaling in of the Tpl2 signaling regulates activation in response to is in cells, and a study of that Tpl2 is a of production in that cell A.G. Wang C.C. Dumitru C.D. Tsichlis P.N. EMBO J. 2003; 22: 3855-3864Crossref PubMed Scopus (138) Google Scholar, 8Sugimoto K. Ohata M. Miyoshi J. Ishizaki H. Tsuboi N. Masuda A. Yoshikai Y. Takamoto M. Sugane K. Matsuo S. Shimada Y. Matsuguchi T. J. Clin. Investig. 2004; 114: 857-866Crossref PubMed Scopus (70) Google Scholar). cell is to cell and in in the that Tpl2 is an of both and of with and of the of Tpl2 in human cell types such 6Rodriguez C. Pozo M. Nieto E. Fernandez M. Alemany S. Cell Signal. 2006; 18: 1376-1385Crossref PubMed Scopus (19) Google Scholar). These to further Tpl2 as a therapeutic target for human inflammatory We have used highly selective and potent inhibitors of Tpl2 activity to several of Tpl2 in human we demonstrate that Tpl2 is required for the LPS-induced activation of MEK and ERK in primary human monocytes. we show that inhibition of Tpl2 LPS- and IL-1β-induced TNFα production in primary human monocytes and human blood. our Tpl2 inhibitors block ERK activation, expression, and the production of various pro-inflammatory mediators in Taken together, our for Tpl2 in human inflammatory cell and they into the of Tpl2 as a target for therapeutic intervention in human inflammatory diseases such as rheumatoid arthritis. used for human human human human and human in Tpl2 inhibitor in for for for for and for with of with and in a in the as and MK2, used for and for for and for used for human MEK1 human human human human human and human for Tpl2 and for which the of Tpl2 and in with with for the Tpl2 inhibitor in for Tpl2 and Tpl2 inhibitor in Tpl2 and MEK1 in in 1% bovine in the Tpl2 and MEK1 with of Tpl2 and MEK1 into and to for with a with in 1% bovine a with of a used for for for for for and for and for CaMKII, EGFR, as Tpl2 and MEK1 and and and and and and human with MEK protein as as Y. A. R. Y. N. H. 2006; PubMed Scopus Google Scholar). Tpl2 inhibitor and in bovine and with of Cell and and in the Cell for and the and in with and human and C. A. J. Tsichlis P.N. S. A. PubMed Scopus Google into a S. J. 2000; Google the of the and by for to the and with and to in with FBS, for inhibitor in DMEM, Tpl2 inhibitors In and the of and by the Cell as by the with the of and and by an inhibition of of in with human and with the of in the these of inhibitor with the in DMEM, to with Cell in and for by a to the the the by to the to a concentration of and the with the Cell for of of with an of with and an of and for the an of and as for and with FBS, cell to in with as by in and for Tpl2 inhibitor for used and used Cell in and cytokine monocytes for and by the in human as N. Y. K. N. A. G. S. Lin L.L. Med. Chem. Lett. 2005; PubMed Scopus Google Scholar). for with San and in to the In to FBS, and Tpl2 inhibitor with Cell in and with for by and for and by with for by with for by the by the and and for Tsichlis These with to to and of with of and by with and in FBS, by and the to various protein by S. and and Cell in and as Cytokine in by A of Tpl2 have developed a series of that and the and of the in series have N. Y. K. N. A. G. S. Lin L.L. Med. Chem. Lett. 2005; PubMed Scopus Google Scholar, Y. N. K. N. S. C. Lin L.L. S. Med. Chem. Lett. 2006; PubMed Scopus Google Scholar). and potent in series and N. Y. K. N. S. J. D. R. J. A. Wang J. S. S. Lin L.L. J. Med. Chem. PubMed Scopus Google Scholar). and in in and of our series of Tpl2 inhibitors as they highly selective for Tpl2 inhibition a of kinases. This to be in TNFα production and other serine/threonine and kinases. an of the highly selective of our Tpl2 inhibitors, the in kinase for the in and as these selective CaMKII, it potent Tpl2 to the in Y. N. K. N. S. C. Lin L.L. S. Med. Chem. Lett. 2006; PubMed Scopus Google the in N. Y. K. N. S. J. D. R. J. A. Wang J. S. S. Lin L.L. J. Med. Chem. PubMed Scopus Google of in a of Tpl2 in for Tpl2 develop a we with a that human Tpl2 by the of Tpl2 the of MEK and ERK and the production and of the pro-inflammatory cytokine This production of is with our W. Lin L.L. Y. J. Biol. Chem. 2003; Full Text Full Text PDF PubMed Scopus Google Scholar). These required the catalytic activity of Tpl2 they in the of the Thus, our activation and production as that by Tpl2 kinase production in a with an of MEK and ERK in these Tpl2 for the LPS-induced of MEK and ERK in we our Tpl2 inhibitors by inhibition of LPS-induced MEK in primary human monocytes. that our Tpl2 in these cells, we a in the Tpl2 and in the monocyte with Tpl2 monocyte and monocyte that Tpl2 for inhibition of monocyte This of in the Tpl2 with activity in the monocyte further by the in with the as and Tpl2 in the with an of and in monocytes it inhibition of and Tpl2 in the with an of and it and in monocytes with of Taken together, these that Tpl2 is the of MEK and ERK in primary human monocytes. of Tpl2 in by of of our for Tpl2 inhibition in primary human monocytes. in LPS-induced MEK and ERK in human monocytes with of for LPS-induced MEK and for ERK of MK2, as a as These demonstrate that selectively Tpl2 in primary human and they with the restricted in ERK activation in C.D. Ceci J.D. Tsatsanis C. Kontoyiannis D. Stamatakis K. Lin J.H. Patriotis C. Jenkins N.A. Copeland N.G. Kollias G. Tsichlis P.N. Cell. 2000; 103: 1071-1083Abstract Full Text Full Text PDF PubMed Scopus (705) Google Scholar, 8Sugimoto K. Ohata M. Miyoshi J. Ishizaki H. Tsuboi N. Masuda A. Yoshikai Y. Takamoto M. Sugane K. Matsuo S. Shimada Y. Matsuguchi T. J. Clin. Investig. 2004; 114: 857-866Crossref PubMed Scopus (70) Google Scholar). to block NF-κB signaling in monocytes with that an into IL-1β-induced activity in as as MAPKKK to MEK is the kinase M. C. Cohen P. Alemany S. J. Biol. Chem. 2003; Full Text Full Text PDF PubMed Scopus Google Scholar, and the inhibition of by our in we monocytes with of and with which selectively the in MEK and ERK These that activity in primary human monocytes. This is with the that in the that is selective for Tpl2 inhibition in we inhibition of LPS-induced TNFα monocyte LPS-induced TNFα with an of which is with the in LPS-induced TNFα production in C.D. Ceci J.D. Tsatsanis C. Kontoyiannis D. Stamatakis K. Lin J.H. Patriotis C. Jenkins N.A. Copeland N.G. Kollias G. Tsichlis P.N. Cell. 2000; 103: 1071-1083Abstract Full Text Full Text PDF PubMed Scopus (705) Google Scholar, 8Sugimoto K. Ohata M. Miyoshi J. Ishizaki H. Tsuboi N. Masuda A. Yoshikai Y. Takamoto M. Sugane K. Matsuo S. Shimada Y. Matsuguchi T. J. Clin. Investig. 2004; 114: 857-866Crossref PubMed Scopus (70) Google Scholar). the that in LPS-induced TNFα by of the to inhibitors with we cell the of the by the to the and to by the activity of which is to the of in the A decrease in the of to as of a In of of primary a 50% in the of the to In the 50% These that for human monocyte of a concentration that of the for LPS-induced TNFα and for TNFα inhibition in these of LPS- and TNFα and production by inhibition inhibition in LPS- inhibition inhibition in LPS- blood. in a that LPS-induced is in K. Ohata M. Miyoshi J. Ishizaki H. Tsuboi N. Masuda A. Yoshikai Y. Takamoto M. Sugane K. Matsuo S. Shimada Y. Matsuguchi T. J. Clin. Investig. 2004; 114: 857-866Crossref PubMed Scopus (70) Google we in primary human monocytes that with LPS-induced in primary monocytes it LPS-induced TNFα We that the pharmacologic inhibition of Tpl2 is for both a and selective in LPS-induced TNFα production in primary human monocytes. of Tpl2 IL-1β-induced and TNFα the of several that the activation of Tpl2-MEK-ERK by the pro-inflammatory cytokine (1Das S. Cho J. Lambertz I. Kelliher M.A. Eliopoulos A.G. Du K. Tsichlis P.N. J. Biol. Chem. 2005; 280: 23748-23757Abstract Full Text Full Text PDF PubMed Scopus (121) Google Scholar, 6Rodriguez C. Pozo M. Nieto E. Fernandez M. Alemany S. Cell Signal. 2006; 18: 1376-1385Crossref PubMed Scopus (19) Google Scholar, 7Stafford M.J. Morrice N.A. Peggie M.W. Cohen P. FEBS Lett. 2006; 580: 4010-4014Crossref PubMed Scopus (37) Google Scholar). we Tpl2 in monocytes. IL-1β-induced MEK and ERK in these cells, with of for IL-1β-induced MEK and for IL-1β-induced ERK IL-1β-induced TNFα production in human with an of C. Pozo M. Nieto E. Fernandez M. Alemany S. Cell Signal. 2006; 18: 1376-1385Crossref PubMed Scopus (19) Google used to Tpl2 in these that Tpl2 is required for IL-1β-induced ERK activation in cell results that the pharmacologic inhibition of Tpl2 in human monocytes IL-1β-induced activation and TNFα production to a approach to that Tpl2 IL-1β-induced ERK activation and TNFα production in the to to and in these ERK in a Tpl2 ERK activation and TNFα production in we the which a C.D. Ceci J.D. Tsatsanis C. Kontoyiannis D. Stamatakis K. Lin J.H. Patriotis C. Jenkins N.A. Copeland N.G. Kollias G. Tsichlis P.N. Cell. 2000; 103: 1071-1083Abstract Full Text Full Text PDF PubMed Scopus (705) Google with and the to These used to the in in LPS, and TNFα ERK in the and of these ERK in results for MEK an of TNFα production in the and in the in LPS-induced TNFα production with the a in TNFα production in the and and in Taken together, these results that Tpl2 is required for IL-1β-induced activation and TNFα production in and they with the pharmacologic inhibition of IL-1β-induced activation and TNFα production in human monocytes by our Tpl2 In the production of IL-6, KC, and the production of IL-6, KC, and and TNFα the production of IL-6, KC, and in LPS- and IL-1β-induced KC, these in the of LPS- and IL-1β-induced TNFα in by the as the in it is to that to joints and in the as of the in of we our Tpl2 inhibitors for inhibition of TNFα production in an in human TNFα with to TNFα production in human LPS- and IL-1β-induced TNFα production in human with of and in the TNFα as with the monocyte TNFα be to a of protein for into the of our Tpl2 inhibitors in human N. Y. K. N. A. G. S. Lin L.L. Med. Chem. Lett. 2005; PubMed Scopus Google Scholar, Y. N. K. N. S. C. Lin L.L. S. Med. Chem. Lett. 2006; PubMed Scopus Google Scholar, N. Y. K. N. S. J. D. R. J. A. Wang J. S. S. Lin L.L. J. Med. Chem. PubMed Scopus Google Scholar). of in by as a and we it inflammatory in in of with for a in ERK and response with an of of with for an in expression and a in and with both and In with for in the of production of and in A.G. Dumitru C.D. Wang C.C. Cho J. Tsichlis P.N. EMBO J. 2002; 21: 4831-4840Crossref PubMed Scopus (233) Google our results that Tpl2 is required for IL-1β-induced expression and production in of inflammatory mediators in by S.E. 50% inhibition of and with of the S.E. 50% inhibition of and with of the S.E. a in response to S.E. In inhibition of MMP-1 with and an for the S.E. S.E. in response to S.E. 50% inhibition of and with of the S.E. a in response to S.E. In inhibition of MMP-1 with and an for the S.E. S.E. in response to in a to IL-6, IL-8, and the matrix metalloproteinases MMP-1 and MMP-3. of can to the and IL-1β-induced IL-6, IL-8, and in the used inhibition of IL-1β-induced MMP-1 in of the in of these these Thus, a IL-1β-induced IL-6, IL-8, and in Tpl2 is required for to TNFα in and (1Das S. Cho J. Lambertz I. Kelliher M.A. Eliopoulos A.G. Du K. Tsichlis P.N. J. Biol. Chem. 2005; 280: 23748-23757Abstract Full Text Full Text PDF PubMed Scopus (121) Google Scholar, 4Eliopoulos A.G. Wang C.C. Dumitru C.D. Tsichlis P.N. EMBO J. 2003; 22: 3855-3864Crossref PubMed Scopus (138) Google we in human and the human cell In our TNFα the production of and other inflammatory mediators in human monocytes and it in monocytes. In production by with TNFα for and by with an of In production of for with TNFα, and with an of Moreover, ERK in by with an of In these TNFα with and the Thus, we that Tpl2 to TNFα in these human cell with protein therapeutics that and TNFα have a for TNFα in the progression of rheumatoid inflammatory and D.L. Drug Discov. Today. 2006; 11: 210-219Crossref PubMed Scopus (63) Google Scholar). Thus, a approach to the of for these diseases is to that block the signaling that TNFα and for we have a series of inhibitors of the Tpl2 of our and and Tpl2 inhibitors highly selective for Tpl2 in our kinase of kinases. of Tpl2 have our of highly selective Tpl2 Tpl2 is the kinase in the human that a of a the in the of the C. A. S.E. Tsichlis P.N. S. A. PubMed Scopus Google Scholar). This Tpl2 to inhibitors that primary Tpl2 is by the kinase inhibitor which in the S. Lin L.L. J. Biol. Chem. 2004; Full Text Full Text PDF PubMed Scopus Google Scholar). A of both the and of our inhibitors be the Tpl2 is of kinase that our Tpl2 inhibitors into a of for Tpl2 inhibition in human monocytes. inhibitors selectively block LPS-induced activation in human monocytes with and they JNK, and NF-κB signaling by and These results with the restricted in ERK activation in C.D. Ceci J.D. Tsatsanis C. Kontoyiannis D. Stamatakis K. Lin J.H. Patriotis C. Jenkins N.A. Copeland N.G. Kollias G. Tsichlis P.N. Cell. 2000; 103: 1071-1083Abstract Full Text Full Text PDF PubMed Scopus (705) Google and they support the notion that the restricted of Tpl2 for in response to in of the Moreover, our demonstrate that Tpl2 is the of MEK and ERK in primary human monocytes. This is by the of in by a of the Tpl2 and monocyte of our of in series with Tpl2 monocyte Thus, in the monocyte is by of should have monocyte of that Tpl2 of for inhibition of monocyte these have and that other in the most for to in human monocytes is to to This the of our inhibitors in the Tpl2 with in the monocyte with of for that Tpl2 catalytic activity is required for the LPS-induced activation of MEK and ERK in primary human monocytes. Tpl2 inhibitors block TNFα production in primary human monocytes and human This is monocytes and for TNFα production in the joints of rheumatoid arthritis and it is that TNFα is in the of other inflammatory diseases M. Maini R.N. Annu. Rev. Immunol. 2001; 19: 163-196Crossref PubMed Scopus (1155) Google Scholar, 12Schottelius A.J. Moldawer L.L. Dinarello C.A. Asadullah K. Sterry W. Edwards 3rd, C.K. Exp. 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IL-1β-induced expression and in and for IL-1β-induced inhibition of IL-1β-induced which is in with the of IL-1β-induced expression Taken with that and expression in A.G. Dumitru C.D. Wang C.C. Cho J. Tsichlis P.N. EMBO J. 2002; 21: 4831-4840Crossref PubMed Scopus (233) Google these that in a signaling that with that Tpl2 is selectively required for ERK activation in that cell with and that Tpl2 is required for JNK, and NF-κB activation (1Das S. Cho J. Lambertz I. Kelliher M.A. Eliopoulos A.G. Du K. Tsichlis P.N. J. Biol. Chem. 2005; 280: 23748-23757Abstract Full Text Full Text PDF PubMed Scopus (121) Google Scholar). A restricted of Tpl2 in ERK activity in as that our Tpl2 inhibitors block and activation in It is that NF-κB is a critical of the expression of and in with C. H. H. A. J. Immunol. 2000; PubMed Scopus Google and and in with the to inhibition Thus, it is that a selective Tpl2 inhibitor IL-1β-induced production in of a for NF-κB in the In our pharmacologic inhibition of IL-1β-induced with in that in IL-1β-induced be to This in the (1Das S. Cho J. Lambertz I. Kelliher M.A. Eliopoulos A.G. Du K. Tsichlis P.N. J. Biol. Chem. 2005; 280: 23748-23757Abstract Full Text Full Text PDF PubMed Scopus (121) Google Scholar). is such a it to these the in which a in IL-1β-induced and it and in affected joints the bone and cartilage with rheumatoid arthritis and other Rheum. 2001; Scholar). In the and and and MMP-1 and in response to IL-1β-induced MMP-1 and expression it to with in rheumatoid and MMP-1 the of cartilage J. M.A. J. 2000; Google Scholar, P. K. T. 2001; PubMed Google Scholar, M.J. Arthritis Rheum. PubMed Scopus Google Scholar). results that Tpl2 inhibition the in by the expression of these It is to that potent MMP-1 and of and These that in of ERK activation required for of these It that the expression of several inflammatory in of Tpl2-MEK-ERK signaling S. A. T. F. D. A. Immunol. 2006; PubMed Scopus (70) Google Scholar). In our be critical for and the many of Tpl2 signaling that In the present they have into various of Tpl2 in human cell and our support to the notion that Tpl2 is a valid target for therapeutic intervention in a of human inflammatory including rheumatoid arthritis. We to and for production of the used in