A potential role of thymic stromal lymphopoietin in the recruitment of macrophages to mouse intervertebral disc cells via monocyte chemotactic protein 1 induction: implications for herniated discs.
OBJECTIVE
To determine whether thymic stromal lymphopoietin (TSLP) plays a role in the resorption of herniated disc tissue.


METHODS
The expression of TSLP messenger RNA (mRNA) and protein in mouse intervertebral disc cells was assessed by quantitative real-time polymerase chain reaction, enzyme-linked immunosorbent assay (ELISA), and immunohistochemical analysis. The ability of mouse intervertebral disc cells to respond to TSLP stimulation was examined by Western blot analysis, ELISA, and protein array analysis. Intracellular signaling pathways involved in TSLP signaling in mouse intervertebral disc cells were investigated using several chemical inhibitors. The role of TSLP in macrophage migration into the intervertebral disc was assessed by in vitro migration assay. Finally, TSLP expression in clinical specimens derived from patients with a herniated disc was examined by immunohistochemistry.


RESULTS
Mouse intervertebral disc cells expressed TSLP mRNA and protein upon stimulation with NF-kappaB-activating ligands such as tumor necrosis factor alpha. In addition, the mouse intervertebral disc cells expressed the TSLP receptor and produced monocyte chemotactic protein 1 (MCP-1; CCL2) and macrophage colony-stimulating factor in response to TSLP stimulation. Both anulus fibrosus and nucleus pulposus intervertebral disc cells expressed MCP-1 upon TSLP stimulation, which was mediated via the phosphatidylinositol 3-kinase/Akt pathway. Consistently, the supernatants of TSLP-activated intervertebral disc cultures had the capacity to induce macrophage migration in an MCP-1-dependent manner. Finally, TSLP and MCP-1 were coexpressed in human herniated disc specimens in which macrophage infiltration into the tissue was observed.


CONCLUSIONS
TSLP induced by NF-kappaB-activating ligands in intervertebral discs may contribute to the recruitment of macrophages to the intervertebral disc by stimulating MCP-1 production and may be involved in the resorption of herniated disc tissue.
Ohba
Tetsuro
T
University of Yamanashi, Yamanashi, Japan.
Haro
Hirotaka
H
Ando
Takashi
T
Koyama
Kensuke
K
Hatsushika
Kyosuke
K
Suenaga
Fumiko
F
Ohnuma
Yuko
Y
Nakamura
Yuki
Y
Katoh
Ryohei
R
Ogawa
Hideoki
H
Hamada
Yoshiki
Y
Nakao
Atsuhito
A
D000818:Animals; D015153:Blotting, Western; D001862:Bone Resorption / Q000503:physiopathology*; D002465:Cell Movement / Q000502:physiology; D002478:Cells, Cultured; D018932:Chemokine CCL2 / Q000378:metabolism*; D016207:Cytokines / Q000502:physiology*; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007150:Immunohistochemistry; D007403:Intervertebral Disc / Q000166:cytology* / Q000502:physiology; D007405:Intervertebral Disc Displacement / Q000503:physiopathology*; D008264:Macrophages / Q000502:physiology*; D051379:Mice; D016328:NF-kappa B / Q000502:physiology; D011506:Proteins / Q000032:analysis; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000094632:Thymic Stromal Lymphopoietin
D018932:Chemokine CCL2; D016207:Cytokines; D016328:NF-kappa B; D011506:Proteins; D012333:RNA, Messenger; D000094632:Thymic Stromal Lymphopoietin