ABSTRACT
<p><b>BACKGROUND</b>Excessive iodine intake and viral infection are recognized as both critical factors associated with autoimmune thyroid diseases. Toll-like receptors (TLRs) have been reported to play an important role in autoimmune and inflammatory disorders. In this study, we aimed to clarify the possible mechanism of TLR3 involved in polyinosine-polycytidylic acid (poly(I:C)) promoting excessive iodine intake induced thyroiditis in non-obese diabetic (NOD) mice.</p><p><b>METHODS</b>Both NOD and BALB/c mice were randomly assigned to four groups: control group (n = 5), high iodine intake (HI) group (n = 7), poly(I:C) group (n = 7) and combination of excessive iodine and poly(I:C) injection (HIP) group (n = 7). After 8 weeks, mice were weighed and blood samples were collected. All the mice were sacrificed before dissection of spleen and thyroid gland. Then, thyroid histology, thyroid secreted hormone, expression of CD3(+) cells and TLR3 as well as inflammatory mRNA level were evaluated.</p><p><b>RESULTS</b>Both NOD and BALB/c mice from HI and HIP group represented goiter and increasing thyroid relative weight. Thyroid histology evidence indicated that only HIP group of NOD mice showed severe thyroiditis with lymphocytes infiltration in majority of thyroid tissue, severe damage of follicles and general fibrosis. Immunofluorescence staining results displayed a large number of CD3(+) cells in HIP NOD mice. Real-time polymerase chain reaction (PCR) results suggested interferon (IFN)-α increased over 30 folds and IFN-γ expression was doubled compared with control group, but interleukin (IL)-4 remained unchanged in HIP group of NOD mice thyroid. Meanwhile, over one third decrease of blood total thyroxine (TT4) and increased thyroid-stimulating hormone (TSH) was observed in HIP group of NOD mice. Only HIP group of NOD mice represented significantly elevation of TLR3 expression.</p><p><b>CONCLUSION</b>Poly(I:C) enhanced excessive dietary iodine induced thyroiditis in NOD mice through increasing TLR3 mediated inflammation.</p>
Subject(s)
Animals , Female , Mice , Inflammation , Metabolism , Iodine , Toxicity , Mice, Inbred NOD , Poly I-C , Pharmacology , Thyroiditis , Allergy and Immunology , Metabolism , Toll-Like Receptor 3 , MetabolismABSTRACT
Objective To observe the effect of iodine excess(HI),polyinosinic-polycytidylic acid[Poly(I:C),Poly]and thyroglobulin(TG)on the thyroid of mice by the expression of Toll-like receptor 3(TLR3)to reveal the functional role of TLR3 in autoimmune thyroiditis.Methods Forty-two non-obese diabetic mice,body weight (20±3)g,were divided into six groups:control group,HI group,Poly group,TG group,HI+TG group,HI+Poly group. Fed with deionized water and injected intraperitoneally with physiological saline 0.1 ml each day for a week, the mice in control group were injected with physiological saline every other day at the same dose for 1 week before they were sacrificed; HI group drank 0.05% NaI water and were injected intraperitoneally with physiological saline same as control group; Poly group drank deionized water and were injected intraperitoneally with poly 0.1 ml (1 g/L)each day of the week, then the mice were injected with Poly every other day at the same dose for 1 week before they were sacrificed; TG group drank deionized water and were injected intraperitoneally with physiological saline same as control group, immunized with 0.1 mg TG by subcutaneously injecting and the immunization was enhanced after they were fed half dose for 4 and 8 weeks separately. In HI + Poly group, the treatment was the same as HI group and Poly group; HI + TG group: the treatment was the same as HI group and TG group. Eight weeks later, mice were sacrificed and thyroids were taken to make frozen sections, Hematoxylin-Eosin (HE) staining was employed to observe the morphological change of the thyroids. The expression of TLR3 of thyroids was observed under fluorescence microscope after Immumofluorescence using TLR3 antibody and TR3-positive cells were analyzed in the thyroid density. Results HE staining showed thyroids of Poly group had no inflammation under microscope.There were different degrees of inflammatory cell infiltration in HI group and TG group. The inflammatory cell infiltration and the damage of follicular thyroid of HI + TG group and HI + Poly group were serious, and the degrees of inflammation were higher over "++". Thyroid follicular epithelial cell with TLR3 expression could be seen in Poly group and HI group, meanwhile, there were TLR3 strong positive inflammatory cells in HI group under fluorescent microscope. Using stereological analysis of TLR3-positive cell density in the thyroid, the difference between groups was statistically significant(F=7.870, P<0.01 ). TLR3-positive cell density in the thyroid of HI + Poly group was higher[ (9.287 ± 0.522)mm2] than control group[ (0.062 ± 0.025)mm2, P < 0.01] significantly, meanwhile, the density in HI + Poly group was higher than HI group [ (2.574 ± 0.257 )mm2] and Poly group[ (1.361 ± 0.148 )mm2, all P < 0.01]. The density in HI + TG group[ (4.843±0.405)mm2] was higher than HI group and TG group[(1.601 ±0.268)mm2, all P < 0.01 )]. Conclusions Excessive iodine and thyroglobulin can induce thyroiditis, and stimulate the expression of TLR3 in the thyroid follicular epithelial, Poly aggravated thyroiditis induced by iodine excess in NOD mice; TLR3 positive inflammatory cells also appeared in inflammatory region, suggesting that TLR3 is involved in the pathogenesis of autoimmune thyroiditis
ABSTRACT
Objective To investigate the influence of iodine excess on expression of TRAIl/TRAIL-sR1 in NOD and Balb/c mice and to study the effect of TRAIl/TRAIL-sR1 on the pathogenesis of experimental autoimmune thyroiditis(EAT). Methods Both Balb/c and NOD mice were divided randomly into control and iodine excess group by feeding with water containing no NaI or 0.05% Nal. The mice were sacrificed after 8 weeks. TRAIL and TRAIL-sR1 mRNA levels were detected by RT-PCR. The function, morphology and apoptosis of thyroids were also observed by ELISA and Tunnel stain. Results Treated by HI, enlarged follicles and flattened epithelium by accumulation of colloid were found in thyroids of both NOD and Balb/c mice. But significant lymphoid cell infiltration and local fibrosis were only found in thyroids of NOD HI group. The relative weight of thyroids of NOD mice in HI group[(104.8±14.5)mg/kg]was heavier than that of control group [(71.8±20.4)mg/kg]. The level of TT4 declined in HI group[(30.77±3.59)mmol/L]compared with control group[(36.43±2.66)mmol/L], meanwhile, the level of TSH was higher in HI group[(6.98±0.66)μg/L]than that in control group [(5.55±0.56)μg/L]. The difference being statistically significant(t=7.773,-9.526,-4.458, all P < 0.05). The relative weight of thyroids of Balb/c mice of HI group[(155.8±20.8)mg/kg]also heavier than that of control group [(105.1±22.0) mg/kg]. The level of TT4 droped in HI group [(19.75±3.32) mmoL/L]was higher than that in control group[(23.46±6.21)mmoL/L], the level of TSH in HI group[(4.14±1.71)μg/L]was higher than that in control group[(3.55±1.41)μg/L], the difference being statistically significant(t=7.554,-7.239,3.140, all P< 0.05). A great deal of apoptotie ceils observed in NOD (3.97±0.91) and Balb/c mice (1.05±0.45) by Tunnel stain were greater than control groups (0.21±0.15, 0.10±0.03), the difference being statistically significant in beth of the two species(t=-7.167,-17.772, both P < 0.05). The apoptosis index of thyroid follicular epithelium in NOD was obviously higher than Balb/c(t=-7.625, P<0.05). The level of TRAIL mRNA did not remarkably change in Balb/c between control group(0.000 59±0.000 39) and HI group(0.001 24±0.000 46, t=-1.940, P>0.05), but it increased apparently in NOD mice HI group(0.018 88±0.005 77) than that of control group(0.009 61± 0.00591, t=-2.71, P<0.05). The level of the expression of TRAIL-sR1 mRNA increased in HI groups of NOD (0.000 53±0.000 15) and Balb/c mice(0.000 42±0.000 09) than that in control groups of NOD(0.000 28± 0.000 05) and Balb/c mice (0.000 17±0.000 06) and the differences were statistically significant between the two species(t=3.050,3.990, all P<0.05). The differences of the expression of TRAIL and TRAIL-sR1 mRNA between the two species were significant(t=-3.37,-4.76, all P<0.05). Conclusions Iodine excess induces colloid goiter in beth species of mice and thyroiditis in NOD mice. The increase of TRAIL and TRAIL-sR1 influenced by iodine excess is one of the molecular bases of follicular epithelium apoptosis and inflammation in thyroids. Genetic factor is a key factor in the pathogenesis of thyroiditis.
ABSTRACT
Objective To observe the different effects of iodine excess on inducing two strain mice thyroiditis. Methods NOD and Balb/c mice, each having 14 mice, were divided into NaI and control group. The mice were given 0.05% NaI water for 8 weeks in NaI group. RIA and ELISA were used respectively to detect TT4, TgAb, TPOAb and TSH level in serum. Morphology changes of thyroid and apoptosis of thyrocytes stained by immunohistochemistry were observed under light microscope. Lymphocytic proliferation of cervical lymph node and spleen to responding to Tg were detected by MTr method. Results After intake of iodine water for 8 weeks, NOD and Balb/c mice showed relative quality of thyroid in Nal group[(104.83±14.52), (155.79±20.77)mg/kg]obviously increased compared with control group[(71.80±20.42), (105.15±21.98)mg/kg, t values:-3.293,-4.429, all P< 0.01)], enlarged follicular lumen with colloid accumulation were observed in thyroid. Serum level of TT4 in Nal group [(29.52±4.42), (19.53± 2.35)nmol/L]to control group[33.40±5.38), (23.47±6.22)nmol/L]of NOD and Balb/c mice showed a decreasing tendency(t values: 1.374,1.567, all P > 0.05). TSH of Nal group showed an increasing tendency in Balb/c mice[(4.14±1.71)μg/L, compared with control [(3.55±1.41)μg/L, t values:-0.705, P > 0.05]and obviously increased in NOD mice [(6.98±0.66)μg/L, compared with control[(555±056)μg/L, t values:-3.562, P< 0.01], but no change of TgAb and TPOAb level in Nal group(1281,1364 cpm, 2.50×103, 0.14×103U/L were observed, compared with control(1297,1220 cpm, 3.17×103,0.03×103 U/L; Zvalues:-0.081,-0.703, -0.244,-1.293, all P > 0.05). In NOD mice NaI group, apoptosis of thyrocytes was more intense than Balb/c mice, obvious infiltration of lymphoeytes, disorganization and focus fibrosis was seen in thyroid. The cell amount of NaI group increased in NOD mice lymph node and spleen cells[(1.100±0.014), (1.076±0.033)]were more than that in the control group [(0.993±0.011), (1.005±0.003), t value:-11.672,-4.314, P < 0.01). Conclusions Iodine leads to enlargement of thyroid and malfunction of thyroid in Balb/c mice. Besides, NOD mice have generate inflammatory reaction in thyroid and produced sensitized lymphocytes to Tg. Iodine excess can induce NOD mice to occur autoimmune thyroiditis.