Molecular mechanisms underlying the pro-inflammatory synergistic effect of tumor necrosis factor alpha and interferon gamma in human microvascular endothelium.
Tumor necrosis factor alpha (TNFalpha) and interferon gamma (IFNgamma) are among the most potent cytokines involved in orchestrating the inflammation response. The molecular mechanisms implicated in the synergism between cytokines are still poorly characterized. We demonstrate that both cytokines dose-dependently stimulate IFNgamma-inducible-protein-of-10-kDa (IP-10) secretion in human microvascular endothelial cells (HMEC-1), showing a potent synergism which is not restricted to IP-10, but is also evident for monokine-induced-by-IFNgamma (MIG) and IL-6 secretion. Immunofluorescence analysis reveals that TNFalpha and IFNgamma converge on a rapid phosphorylation of ERK, which however results in a different subcellular compartmentalization of the activated enzyme in response to the two cytokines. Differences in the subcellular recruitment of ERK in response to IFNgamma and TNFalpha are responsible for generating different ERK downstream signaling, which can thus synergize on the secretion of IP-10 as well as of other cytokines/chemokines. The importance of ERK activation in mediating the synergism of the two cytokines is further confirmed by the inhibitory effect of the anti-diabetic drug rosiglitazone and ERK blockers on IP-10, MIG and IL-6 secretion. A further mechanism of synergism involving the reciprocal upregulation of TNFalpha-RII and of IFNgamma-R, in response to IFNgamma and TNFalpha, respectively, was revealed by flow cytometry and quantitative real time RT-PCR analysis.
Department of Clinical Physiopathology, DENOthe Center of Excellence for Research, Transfer and High Education, University of Florence, Viale Pieraccini 6, I-50139 Florence, Italy.
Adriana
A
Lombardi
Giulia
G
Cantini
Tommaso
T
Mello
Michela
M
Francalanci
Stefania
S
Gelmini
Lorenzo
L
Cosmi
Veronica
V
Santarlasci
Selene
S
Degl'Innocenti
Paola
P
Luciani
Cristiana
C
Deledda
Francesco
F
Annunziato
Gianni
G
Forti
Andrea
A
Galli
Mario
M
Serio
Michaela
M
Luconi
D002478:Cells, Cultured; D054357:Chemokine CXCL10 / Q000378:metabolism; D018925:Chemokines / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D007249:Inflammation / Q000378:metabolism / Q000473:pathology; D007371:Interferon-gamma / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D015854:Up-Regulation
C114753:CXCL10 protein, human; D054357:Chemokine CXCL10; D018925:Chemokines; D016207:Cytokines; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma