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Experimental Studies |
Department of Medicine, University of Sheffield, Clinical Sciences Centre, Northern General Hospital, Sheffield S5 7AU, United Kingdom
| Abstract |
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(IFN-
). IL-12 p40 gene expression was
identified in 2 of 10 MNG samples, 6 of 12 GD, and 3 of 4 HT. HT-ori3
and primary thyroid cell cultures were positive for IL-12 p40 messenger
RNA (mRNA) expression in both unstimulated and stimulated cell
cultures. IL-13 mRNA was expressed in 2 MNG, 9 GD, and 1 HT sample.
Both HT-ori3 and primary thyroid cultures expressed IL-13 after TSH,
IL-1, or IFN-
stimulation; unstimulated primary cultures of thyroid
cells, however, did not express IL-13. IL-15 gene expression was
detected in 8 MNG, 8 GD, and 4 HT samples. HT-ori3 and primary thyroid
cell cultures, stimulated with TSH, IL-1, or IFN-
, showed expression
of this cytokine. Unstimulated cells showed only a weak expression. Our
results indicate that the cytokine patterns in the various diseases
studied are heterogeneous; that thyroid cells can express IL-12, IL-13,
and IL-15 mRNA in culture, particularly after TSH, IL-1, or IFN-
stimulation; and that IL-15 is expressed in most of the tissue samples
studied. | Introduction |
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IL-12, IL-13, and IL-15 are recently defined cytokines that have not
been studied previously in autoimmune thyroid disease in man. IL-12 is
a heterodimeric cytokine composed of two subunits, p35 and p40, and is
produced primarily by activated monocytes (reviewed in Ref.16).
Transcripts of p35 gene are constitutively expressed in most cells
studied, whereas p40 messenger RNA (mRNA) is usually restricted to
cells able to produce the heterodimeric IL-12 (17), and its expression
is more tightly regulated than that of p35 (18, 19). IL-12 enhances the
cytotoxic activities of natural killer (NK) and T cells and induces the
production of several cytokines, especially interferon-
(IFN-
).
This cytokine therefore is likely to be involved in the generation of
the Th1 helper T cell subset, which mediates delayed type
hypersensitivity responses (20).
IL-13 is mainly produced by Th2 cells, the T cell subset which provides help for humoral immune responses, although Th1 cells also can produce IL-13 in man. IL-13 shares many features with IL-4, including priming towards a Th2 response. However, its biological activities seem to be more restricted (reviewed in Ref.21). Finally, IL-15 has similar properties to IL-2, in that it stimulates the proliferation of both T and B cells (22, 23). In contrast to IL-2, IL-15 is not produced by T cells, although a large variety of tissues and cells can produce this cytokine (22).
In view of the potential importance of IL-12, IL-13, and IL-15 in immune responses in general, and autoimmunity in particular, we have analyzed IL-12, IL-13, and IL-15 gene expression by RT-PCR in thyroid tissue samples obtained from patients with nontoxic multinodular goiter (MNG), Graves disease (GD), and Hashimotos thyroiditis (HT). This was complemented by in vitro studies carried out on primary TFC cultures and on the immortalized human thyroid cell line, HT-ori3, to determine whether TFC are a possible source of these cytokines.
| Materials and Methods |
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Tissue samples were processed, as described below, to obtain primary TFC cultures or immediately snap frozen in liquid nitrogen. The diagnosis was confirmed in all the patients by histological examination. All HT patients had high-antibody titers against thyroid peroxidase (anti-TPO), whereas 7 of 10 GD patients had raised anti-TPO titers, with data unavailable in another 2. All patients with HT and GD had been treated with T4 and carbimazole, respectively, before surgery. Local ethical committee approval was obtained, and all tissue samples were taken after informed consent.
Thyroid cell culture
The HT-ori3 cell line was established by transfection of normal
thyroid cells with a plasmid-borne origin-defective SV40 genome as
previously described (24). This cell line expresses features of thyroid
epithelial function, including iodide trapping and thyroglobulin
production. Primary TFC cultures were prepared from GD thyroidectomy
specimens using methods described elsewhere (25). Both HT-ori3 and
primary cell cultures were grown to confluence in 25-cm2
flasks and treated with IL-1, bovine TSH, or recombinant IFN-
as
previously described (3). RNA was extracted from cell cultures after
12 h of stimulation.
RNA extraction and complementary DNA (cDNA) synthesis
RNA was extracted from thyroid cell culture and whole tissue (3-mm3 pieces) by using TRIzol (Gibco, Paisley, UK) according to the manufacturers protocol. Moloney murine leukemia virus RT was used to synthesize cDNA as previously described (3).
PCR amplification
PCR was performed in 50 µL amplification reaction, which contained: 5 µL of 10 x concentrated buffer (15 mmol/L MgCl2, 100 mmol/L Tris HCl pH 8.3, 0.1% gelatin, 500 mmol/L KCl, 1% Tween 20, 1% Nonidet NP40; all from Sigma, Poole, Dorset, UK), 2.5 units of Taq DNA polymerase (Promega, Southampton, UK), 0.1 mmol/L of each deoxyribonucleotide triphosphate, 1.5 µL cDNA, and 41 µL autoclaved deionized water.
Amplifications were carried out using cycles of 94 C for 1 min, 55 C for 1 min, and 72 C for 1 min. ß-actin was used as a control for the integrity of cDNA in the samples, and its amplification was performed using 27 cycles. Thirty-five cycles were used to amplify IL-13 cDNA and 39 cycles for the detection of IL-12 and IL-15.
To provide a positive control, normal peripheral blood mononuclear cells (PBMC) were stimulated with phytohemagglutinin M (PHA; Gibco; 1 µg/mL) for 24 h. Adherent PBMC were stimulated for 4 h with lipopolysaccharide (LPS) (10 µg/mL; Sigma). RNA was extracted from these two preparations, pooled together, and used to prepare cDNA as described above. The oligonucleotide primers and probes were designed according to previously published sequences of IL-12 (26), IL-13 (27), and IL-15 (22). The primer sequences were as follows: IL-12 p40: sense 5'-TACTCCTTGTTGTCCCCTCTG-3', antisense 5'-GTGGCCATATGGGAACTGAAG-3'; IL-13: sense 5'-GAAGACCCAGAGGATGCT-3', antisense 5'-CCGCCTACCCAAGACATT-3'; IL-15: sense 5'-CAAGATCGTATTGTATTGTAGGA-3', antisense 5'-ACATTTGGACAATATGTACAAAA-3'.
The primer sequences for ß-actin have been described previously (3).
Control reactions without cDNA were carried out in parallel and were consistently negative.
Oligonucleotide hybridization
Product identification was confirmed by hybridization using internal oligonucleotide probes as previously described (3). Probe sequences were as follows: IL-12 probe: 5'-CAGTACTAGTTTGACATTCAG-3'; IL-13 probe: 5'-CGCACAAGGTCTCAGCTG-3'; IL-15 probe: 5'-ACCGTGGCTTTGAGTAAT-3'.
The probe for ß-actin has been described previously (3).
Statistics
Results were compared by 2 x 2 contingency tables and the
2 test (two-tailed).
| Results |
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Ten MNG, 12 GD, and 4 HT tissue samples were analyzed for IL-12,
IL-13, and IL-15 gene expression by RT-PCR. Representative results are
illustrated in Fig. 1
, where lanes 15 represent MNG,
lanes 611, GD, and lanes 1215, HT tissue samples. C+
represents the positive control obtained from PHA- and LPS-stimulated
PBMC.
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2 = 2.12, P > 0.05 compared with MNG)
and in 3 of the HT samples. Only 2 MNG and 1 HT samples expressed
IL-13, whereas 8 GD samples showed bands for IL-13 (
2 =
4.79, P < 0.03 compared with MNG). Eight of 10 MNG
samples expressed IL-15; 9 GD samples showed also its expression
(
2 = 0.48, P > 0.05 compared with MNG).
IL-15 was detected in all HT samples. TFC and HT-ori3 cultures
The results of experiments to detect IL-12, IL-13, and IL-15 mRNA
in cultured thyroid cells by RT-PCR are shown in Fig. 2
.
Lanes 14 represent cultured HT-ori3 cells, whereas lanes 58 are
primary TFC cultures from a patient with GD. These cells were used
either unstimulated (lanes 1 and 5) or stimulated with IL-1 (lanes 2
and 6), TSH (lanes 3 and 7), or IFN-
(lanes 4 and 8). C+
represents the positive control obtained from PHA- and LPS-stimulated
PBMC. Using methods previously described (3), cDNA samples from both
unstimulated and stimulated cells were equilibrated on the basis of the
yield of ß-actin-specific PCR product, enabling approximate
semiquantitation of the cytokines studied.
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, there was an enhanced expression
of IL-13 and IL-15, with IL-13 becoming detectable in the primary
thyrocyte cultures. This experiment was repeated on two further
occasions using TFC from separate GD patients, as well as replicate
HT-ori3 cells, with similar results. | Discussion |
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IL-12 induces IFN-
production and is thought to play a critical role
in the development of Th1 immune response (20). A recent study of
BioBreeding (BB) autoimmune-thyroiditis-prone rats has shown that IL-12
p40 gene expression increases in the thyroid gland with the progression
of the thyroiditis, implicating IL-12 in the perpetuation, if not the
initiation, of the disease (31). In our study, 3 of 4 HT thyroid
samples and 6 of 12 GD samples expressed IL-12 p40. Although IL-12 p40
was constitutively expressed in thyroid cultures, suggesting a
contribution by TFC to IL-12 expression, it was detected in only 2 of
the MNG tissue samples. This could be caused by unknown inhibitory
factors operating to suppress IL-12 expression in vivo, or
it could be simply caused by low levels of expression in this mixed
cellular population.
IL-13 suppresses the production of proinflammatory cytokines and
facilitates a Th2 response resulting in antibody synthesis (21). IL-4
is a key cytokine product of Th2 cells for this response. Previous
studies on tissue IL-4 mRNA expression in GD have given conflicting
results, in that IL-4 was either not expressed or found in a minority
or detected in all of the samples analyzed (28, 29, 32). A recent study
using quantitative RT-PCR has demonstrated a correlation between tissue
IL-4 mRNA levels and serum levels of anti-TPO in patients with GD (33).
The majority of our GD tissue specimens expressed IL-13, and all but
one of the samples from patients with high anti-TPO titers showed IL-13
expression, suggesting a role for this cytokine in intrathyroidal
autoantibody synthesis. However, one sample from a patient with
undetectable anti-TPO also expressed IL-13; pretreatment with
antithyroid drugs may have influenced antibody levels in these
patients. Although anti-TPO antibody was detected in all HT patients,
only one tissue sample expressed IL-13, but three of these samples,
including the sample expressing IL-13, showed IL-4 expression (data not
shown). IL-13 was either not detected or expressed as a faint band in
unstimulated primary or HT-ori3 cell cultures, respectively. However,
the results after TSH, IL-1, or IFN-
stimulation indicate that TFC
could be a source of IL-13 in pathological settings.
IL-15 induces T and B cell proliferation (22, 23). This cytokine is
expressed by a wide range of human tissues and cell lines, including
skeletal muscle, placenta, and epithelial cell cultures (22). In
keeping with this, IL-15 mRNA was detected in the majority of thyroid
tissue samples from patients with MNG, GD, and HT. Furthermore,
unstimulated primary TFC and HT-ori3 cultures expressed IL-15, and the
expression was increased after stimulation of these cells with TSH,
IL-1, or IFN-
, suggesting that TFC are a source of IL-15 in the
thyroid. IL-15 is known to have noninflammatory actions because it can
be detected in normal muscle tissue, where it is thought to have an
anabolic activity (34). Although we have found a significant difference
in IL-13 gene expression between the GD and the MNG, differences in
IL-12 or IL-15 mRNA expression did not reach statistical significance.
This could be caused by the variable contribution of TFC to expression
of IL-12 and IL-15 by thyrocytes in both disorders, discussed above.
Another possibility is the involvement of autoimmunity in the
pathogenesis of MNG (35), making normal thyroid tissue the ideal
control, but unfortunately, we have been unable to obtain truly normal
thyroid. The HT group was not included in the statistical analysis
because of the limited number of samples analyzed.
In summary, this study demonstrates the ability of TFC to express
IL-12, IL-13, and IL-15 mRNA in culture, particularly after stimulation
with TSH, IL-1, and IFN-
. IL-15 was detected in most of the thyroid
tissue specimens studied. IL-12 and IL-13 were detected with varying
frequencies in GD and HT tissue samples, whereas only a minority of MNG
samples expressed these two cytokines. These results suggest that
intrathyroidal production of IL-12, IL-13, and IL-15 are involved in
the pathogenesis of autoimmune thyroid diseases.
| Acknowledgments |
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| Footnotes |
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2 To whom correspondence and requests for reprints should be
addressed. ![]()
Received June 19, 1996.
Revised August 29, 1996.
Accepted October 7, 1996.
| References |
|---|
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production of thyroid
infiltrating lymphocytes in Hashimotos thyroiditis: a peculiar
feature of thyroid autoimmunity. Autoimmunity. 4:267276.[Medline]
, interleukin-6 and
interleukin-8 mRNA expression by human thyrocytes. J Mol Endocrinol. 15:1121.
and interleukin-6. Clin Exp Immunol. 77:324330.[Medline]
by human
thyroid epithelial cells. Immunology. 75:456462.[Medline]
induces HLA-DR expression by
thyroid epithelium. Clin Exp Immunol. 11:265273.
(TNF) and
-interferon
(
-IFN-) on rat thyroidal cell growth and Ia antigen expression. Immunology. 63:285289.[Medline]
,
separately and added together with interleukin-1ß, on the function of
cultured human thyroid cells. J Endocrinol. 143:359365.
. Thyroid. 3:325330.[Medline]
production by suppressing natural killer cell stimulatory
factor/IL-12 synthesis in accessory cells. J Exp Med. 178:10411048.
production by mouse T
helper clones that are unresponsive to B7 costimulation. J Exp Med. 180:223231.
and IL-12p40 mRNA increase with age in both
diabetic and insulin-treated nondiabetic BB rats. J Immunol. 156:13151321.[Abstract]
producing thyroid-derived T cells are
detected in Graves disease, thyroid autonomy as well as in non-toxic
multinodular goiter. Eur J Endocrinol. 135:6068.This article has been cited by other articles:
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