Endogenous IL-15 sustains recruitment of IL-2Rbeta and common gamma and IL-2-mediated chemokine production in normal and inflamed human gingival fibroblasts.
We recently reported that anti-IL-15 neutralizing mAb has been shown to inhibit production of MCP-1 in response to IL-2 from normal human gingival fibroblasts (HGF), the major constituent of gingival tissue. In the present study, we examined the expression of IL-2R and IL-15R subunits in HGF from normal and inflamed regions and the role of endogenous IL-15 in IL-2-mediated signaling. Normal HGF expressed IL-2Rbeta and common gamma-chain (gammac) but not IL-2Ralpha or IL-15Ralpha, whereas inflamed HGF expressed IL-2Ralpha, IL-15Ralpha, IL-2Rbeta, and gammac, as assessed by RT-PCR and flow cytometry. Exogenous IL-2 and IL-15 induced production of MCP-1 but not IL-8 in normal HGF, and induced the production of both chemokines in inflamed HGF. Both HGF constitutively transcribed the 48 aa-IL-15 isoform, and the isoform was not actively secreted but rather existed as a membrane-bound form. Pretreatment with anti-IL-15 neutralizing mAb for 24 h completely inhibited the production of MCP-1 induced by IL-2 and IL-15 and IL-2-induced phosphorylation of Jak 1 and 3 in HGF. The pretreatment and RNA interference targeted to IL-15 mRNA resulted in total inhibition of the IL-2Rbeta and gammac expression at mRNA and protein levels. Furthermore, excess amounts of IL-2 restored the inhibitory effect of anti-IL-15, inhibition of NF-kappaB abrogated the expression of IL-2Rbeta and gammac, and IL-2-induced-nuclear translocation of NF-kappaB was completely inhibited by the RNA interference in HGF. These results suggest that endogenous membrane-bound IL-15 sustains recruitment of IL-2Rbeta and gammac through activation of NF-kappaB in HGF.
Division of Oral Immunology, Department of Oral Biology, Tohoku University Graduate School of Dentistry, Aoba-ku, Sendai, Japan.
Akiko
A
Ozawa
Hiroyuki
H
Tada
Yumiko
Y
Sugawara
Akiko
A
Uehara
Takashi
T
Sasano
Hidetoshi
H
Shimauchi
Haruhiko
H
Takada
Shunji
S
Sugawara
D000328:Adult; D018925:Chemokines / Q000096:biosynthesis*; D005347:Fibroblasts / Q000276:immunology / Q000378:metabolism; D005881:Gingiva / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D019409:Interleukin-15 / Q000502:physiology*; D007376:Interleukin-2 / Q000494:pharmacology*; D016328:NF-kappa B / Q000502:physiology; D010518:Periodontitis / Q000276:immunology*; D021122:Protein Subunits; D053647:Receptors, Interleukin-15; D015375:Receptors, Interleukin-2 / Q000032:analysis / Q000378:metabolism*; D015398:Signal Transduction
D018925:Chemokines; C508024:IL15RA protein, human; D019409:Interleukin-15; D007376:Interleukin-2; D016328:NF-kappa B; D021122:Protein Subunits; D053647:Receptors, Interleukin-15; D015375:Receptors, Interleukin-2