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* Department of Allergy and Immunology, Faculty of Medicine,
Division of Functional Genomics and Systems Medicine, Research Center for Genomic Medicine, Saitama Medical University, Saitama, and
First Department of Internal Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan
| Abstract |
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| Introduction |
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| Materials and Methods |
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IL-1β, TNF-
, IL-6, TGFβ, IL-12, IL-23, anti-IL-4 Ab, and anti-IFN-
Ab were purchased from PeproTech; IL-4 and GM-CSF were purchased from Primmune. IL-17, IL-5, IL-4, IL-13, IFN-
, and CXCL13 ELISA kits were purchased from R&D Systems.
Preparation of human monocyte-derived dendritic cells and T lymphocytes
Human CD14+ cells were isolated from PBMC by Ficoll-Paque (GE Healthcare) centrifugation and positive selection using CD14 MicroBeads (Miltenyi Biotec). These cells were further depleted with CD4+ T cell isolation kit (Miltenyi Biotec) and separated into CD45RO+ memory T cells and CD45RA+ naive T cells through the use of CD45RO MicroBeads (Miltenyi Biotec). The purity of these cells was >99% as assayed by a FACScan flow cytometer (BD Biosciences). The CD14+ cells were suspended in RPMI 1640 medium containing 10% FCS, 1% L-glutamine, 50 IU/ml penicillin, 50 µg/ml streptomycin, 50 ng/ml IL-4 and GM-CSF and were cultured at 37°C in a humidified atmosphere with 5% CO2. After 5 days, cells were harvested as immature monocyte-derived dendritic cells (Mo-DC).3 This study, which used the peripheral blood of healthy volunteers, was approved by the Saitama Medical University Ethics Committee.
MLR and cytokine measurement by ELISA
Immature Mo-DCs were further cocultured with HLA-DR-nonshared allogeneic CD4+ naive T cells to induce MLR. Alternatively, HLA-DR-nonshared PBMC of two donors (2 x 103/individual donor/well of microculture plate 163118; Nunc) were cocultured to induce MLR. IL-1β (10 ng/ml), TNF-
(10 ng/ml), IL-6 (20 ng/ml), and TGFβ (10 ng/ml) were added in these MLR cultures. After an 8-day culture, the wells where cells proliferated were typically 10% of all the culture wells. The proliferating wells were split into two wells of a 96-well flat-bottom culture plate (Falcon), followed by feeding with irradiated (45 Gy) PBMC used for MLR (1 x 105/well) plus IL-23 (10 ng/ml). After 6 days of culture, the supernatant fluids were harvested to be subjected to IL-17, IL-5, IL-4, IL-13, and IFN-
determination by ELISA. After an additional 24-h culture, typical Th1, Th2, and Th17 cells were cloned by limiting dilution at 0.3–1.0 T cells/well in the presence of irradiated PBMC. CXCL13 production by Th1, Th2, and Th17 cell clones in the frozen culture supernatant fluids was determined by ELISA.
T cell clones specific for Candida albicans
PBMC (5 x 103/microculture well) were cocultured with 100 µg/ml C. albicans Ag (Torii Pharmaceuticals). The determination of cytokine production and limiting dilution was performed as described in the previous section.
Collection of culture supernatants
Allo-specific and C. albicans-specific T cells (3 x 104/well) were stimulated with irradiated allogenic PBMC and irradiated autologous PBMC (1.5 x 105/well) plus C. albicans Ag (10 µg/ml), respectively, in a 96-well flat-bottom microculture plate. Alternatively, cloned T cells were stimulated with PMA (10 ng/ml) plus ionomycin (1 µg/ml). The supernatant fluid specimens were then harvested 16 and 48 h after the initiation of culture, for IL-4 and the other cytokines, respectively.
DNA chip analysis
The total RNA was extracted from M97.1, W10.1, and W110.1 cell clones using RNeasy mini kit (Qiagen) according to the manufacturers instructions. To minimize the contamination of signals due to irradiated PBMC which were added as APCs, the cell preparations were expanded by anti-CD3 plus anti-CD28 Abs before RNA extraction. A gene expression analysis was performed using Affymetrix GeneChip according to the manufacturers instruction. In brief, 5 µg of total RNA was reverse transcribed and second strand cDNA was obtained, then cRNA was synthesized by in vitro transcription, incorporating biotin-labeled nucleotide. Fragmented cRNA was hybridized on Affymetrix GeneChip mouse Genome 430 2.0, and stained by streptavidin PE. After scanning, the quantified data was analyzed by MAS5 normalization and visualized by Spotfire DecisionSite (Spotfire).
RT-PCR
RNA was extracted using the TRIzol reagent (Invitrogen). First-strand cDNA synthesis was performed using the SuperScript II RnaseH– reverse transcriptase (Invitrogen), and cDNA was amplified using AmpliTaq Gold DNA polymerase (Applied Biosystems). The sense and antisense primers specific for β-actin gene were designed as described previously (9). The sense and antisense primer sequences specific for CXCL13 gene were 5'-TGTGTGTGTGGACCCTCAAG-3' and 5'-CAGAGCAGGGATAAGGGAAG-3', respectively. The transcripts were amplified by 30 cycles of the following: cDNA denaturation (30 s at 95°C), followed by 60 s of primer annealing at 57°C, and 60 s of extension at 72°C. The PCR products were subjected to electrophoresis on 1.5% agarose gel and then were visualized by ethidium bromide staining.
Synovial fluid specimens
Fourteen patients with rheumatoid arthritis (RA) and 13 control patients with osteoarthritis (OA)3 were diagnosed according to the American College of Rheumatology criteria (10). Synovial fluid specimens were collected during either diagnostic or therapeutic arthrocentesis of the knee (14 knees in 14 cases with RA or 13 knees in 13 cases with OA). All synovial samples were collected under sterile conditions, and the cellular components were removed immediately after centrifugation. The supernatants were stored at –30°C.
Statistics
Comparisons between the sets of two groups were performed using Students two-tailed t test.
| Results |
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Previous reports have pointed out that IL-2 and IFN-
have an inhibitory effect on the development and maintenance of Th17 cells (11). We, therefore, used limiting dilution conditions as described in Materials and Methods for the primary culture of T cells because such conditions are less likely to allow for cell-cell interactions that negatively affect the development of Th17 cells via a bystander effect of IL-2 and IFN-
. Furthermore, allo-reactive T cells are mainly composed of naive CD4+ T cells (9, 12, 13), and these T cells exist in the peripheral blood at a higher clonal frequency in comparison to naive CD4+ T cells specific for exogenous Ags. We, therefore, attempted to establish Th17 clones by HLA-DR-nonshared MLR, in the presence of IL-1β, TNF-
, IL-6, and TGFβ. For the establishment of allo-reactive Th1 and Th2 cell clones, IL-12 plus anti-IL-4 Ab and IL-4 plus anti-IFN-
Ab were used, respectively. Typical Th1, Th2, and Th17 cell clones were established. Among them, clones M97.1, W10.1, W110.1, and M123.1 as shown in Table I were used for further analysis. They exhibited typical cytokine production patterns when stimulated by MLR, i.e., in an Ag-specific manner. However, when they were stimulated by PMA plus ionomycin, i.e., in an Ag-nonspecific manner, minor contaminating signals were thus detected. They are likely to be attributable to irradiated PBMC which were added to the culture as APCs.
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The differences in the gene expression among three cell lines were compared by using the Affymetrix GeneChip system. Because contaminating signals were detected as shown in Table I, the T cell preparations were further expanded by anti-CD3 plus anti-CD28 Abs before RNA extraction. The normalized expression data were visualized in Fig. 1. The CXCL13 expression as indicated by the arrows was high in Th17 cells, whereas that in Th1 and Th2 cells was none and trace, respectively. Table II shows typical Th17-specific transcriptomes. CCL20 (14), IL-26 (14), RORC (human analog of RORgt) (15), and CXCL13 were preferentially expressed by Th17 clone W110.1. In contrast, none of the three clones expressed CCR6 (16, 17) at high levels. We next performed a RT-PCR analysis for CCR6. Indeed, CCR6 was expressed by Th17, but not by either Th1 or Th2 (data not shown). This discrepancy might be attributable to the probe for CCR6 loaded on the DNA chip.
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To confirm the results of transcriptome analysis, we next examined the expression patterns of CXCL13 mRNA by the Th cell clones, using RT-PCR. As shown in Fig. 2, the Th17 cells exhibited a marked expression of CXCL13 mRNA, whereas none of the Th1 and Th2 cells did. The Th2 cells exhibited a very faint band when much volume was loaded (data not shown).
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To correlate the cytokine production profile and CXCL13 production in Th cell populations, we compared concentrations of CXCL13 in culture supernatant fluids using allo-reactive Th1, Th2, and Th17 cells. As shown in Fig. 3, none of the Th1 cells exhibited CXCL13 production, whereas all Th17 cells exhibited a marked production of CXCL13. Although most of Th2 cells exhibited a small expression of CXCL13, minor proportion of Th2 cells expressed >200 pg/ml CXCL13. To confirm that the correlation of IL-17 and CXCL13 is not limited to allo-reactive Th cells, we performed the same analysis using Th17 cell clones specific for C. albicans Ag. As shown in Fig. 4, a clear correlation of IL-17 and CXCL13 was observed, indicating that the Th17 cell clones differentiated in physiological conditions carry the same property. To confirm the reproducibility of these results and to rule out any donor-to-donor variance, we established Th1, Th2, and Th17 clones specific for C. albicans, by using PBMC from nine healthy individuals. As shown in Table III, CXCL13 was preferentially produced from Th17 cells.
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To further confirm the association between Th17 and CXCL13, not only under physiological conditions but also in Th17-associated human disease, synovial fluid specimens from patients with RA were collected and analyzed for IL-17 and CXCL13. The synovial fluid specimens from patients with OA were analyzed as controls. As shown in Table IV, CXCL13 exhibited markedly higher levels in RA, in comparison to OA (p < 0.01). Furthermore, a statistically significant correlation between IL-17 and CXCL13 was observed by using Spearmans rank correlation (p < 0.01).
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| Discussion |
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Because studies by others (18) have shown controversial effects of TGFβ and IL-6 on human Th17 cells, we checked the efficiency for the establishment and maintenance of human Th17 cells. Indeed, TGFβ exhibited an inhibitory effect on the establishment of Th17 (by 50%; data not shown), whereas the addition of IL-6 exhibited an enhancing effect (data not shown). We also tried adding IL-23, not only for maintenance but also for the establishment of Th17, and we found that IL-23 increased the efficiency of the establishment of Th17 (14).
B cells in mice lacking CXCR5 do not migrate from the T cell-rich zone into B cell follicles in the spleen or the Peyers patches (19). Therefore, the ligand for CXCR5, which has now been identified as CXCL13 (20), is essential for B cell migration within a specific anatomical compartment. Not only Th cells but also B cells are reported to play pivotal roles for the development of murine autoimmune diseases. For example, collagen-induced arthritis, where Th17 cells contribute much to the development of arthritis (3, 4, 5, 6), can be adoptively transferred by an autoantibody alone (21). Because CXCL13 is one of the powerful B cell chemoattractants, it is highly likely that Th17 cells can effectively and closely interact with B cells for the production of autoantibodies. In the case of protective immunity to extracellular microorganisms, such an interaction should allow B cells to produce protective Abs that can help in terminating the infection. Indeed, Acosta-Rodriguez et al. (18) reported that Th17 cells carry Ig class-switching activity. However, the effect of Th17 cells on IgG subclasses remains obscure. Further studies regarding such Th17-B cell interaction both in vitro and in vivo are currently underway.
| Disclosures |
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| Footnotes |
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1 This work was supported in part by an Internal Research Grant from Saitama Medical University and a Research Grant-In-Aid for Scientific Research by the Ministry of Health, Labor and Welfare of Japan, the Ministry of Education, Culture, Sports, Science and Technology of Japan. ![]()
2 Address correspondence and reprint requests to Dr. Sho Matsushita, Department of Allergy and Immunology, Faculty of Medicine, Saitama Medical University, 38 Morohongo, Moroyama, Saitama 350-0495, Japan. E-mail address: shomat{at}saitama-med.ac.jp ![]()
3 Abbreviations used in this paper: Mo-DC, monocyte-derived dendritic cells; OA, osteoarthritis; RA, rheumatoid arthritis. ![]()
Received for publication October 9, 2007. Accepted for publication April 30, 2008.
| References |
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t directs the differentiation program of proinflammatory IL-17+ T helper cells. Cell 126: 1121-1133. [Medline]This article has been cited by other articles:
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Z. Jaffar, M. E. Ferrini, L. A. Herritt, and K. Roberts Cutting Edge: Lung Mucosal Th17-Mediated Responses Induce Polymeric Ig Receptor Expression by the Airway Epithelium and Elevate Secretory IgA Levels J. Immunol., April 15, 2009; 182(8): 4507 - 4511. [Abstract] [Full Text] [PDF] |
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H. Hamada, M. d. l. L. Garcia-Hernandez, J. B. Reome, S. K. Misra, T. M. Strutt, K. K. McKinstry, A. M. Cooper, S. L. Swain, and R. W. Dutton Tc17, a Unique Subset of CD8 T Cells That Can Protect against Lethal Influenza Challenge J. Immunol., March 15, 2009; 182(6): 3469 - 3481. [Abstract] [Full Text] [PDF] |
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