Thyroglobulin autoantibodies of patients with subacute thyroiditis are restricted to a major B cell epitope.

BACKGROUND: Thyroglobulin autoantibodies (TgAb) can develop in patients with subacute thyroiditis (SAT). AIM: Comparison of the epitope pattern of TgAb of patients with SAT, Hashimoto's thyroiditis (HT) [autoimmune thyroid disease (AITD)] and non-toxic multinodular goiter (NTMG) (non-AITD). SUBJECTS AND METHODS: Serum TgAb from 10 patients with SAT, 45 with HT, and 19 with NTMG were evaluated. Serum TgAb binding to Tg was inhibited by 4 recombinant human TgAb-Fab, recognizing Tg epitope regions A, B, C, and D. The ability of single TgAb-Fab to inhibit the binding of serum TgAb to Tg was evaluated in enzymelinked immunosorbent assay. RESULTS: Levels of inhibition were different for all TgAb-Fab in the 3 groups of patients. Inhibition by region A TgAb-Fab in SAT [50.5 (30.3-62.5)%] (median and 25th to 75th percentiles) was similar to HT [49.0 (38.0-69.5)%] and significantly higher than in NTMG [25.0 (14.0-37.0)%]; by region B TgAb-Fab in SAT [0.0 (0.0-12.5)%] was significantly lower than in HT [28.0 (9.5-48.0)%] and similar to NTMG [9.0 (4.8-20.5)%]; by region C TgAb-Fab in SAT [9.5 (0.0-25.8)%] were similar to HT [23.0 (9.5-41)%] and NTMG [6.5 (1.7-21.5)%]; and by region D TgAb-Fab in SAT [0.0 (0.0-8.0)%] were lower than in HT [12.0 (1.0-28.5)%] and similar to NTMG [1.0 (0.0-5.0)%]. CONCLUSIONS: The epitope pattern of TgAb of SAT is restricted to the A region that is immunodominant in AITD and non-AITD. In the majority of patients with SAT, the autoimmune phenomena represent a non-specific and transient response to the release of thyroid antigens, rather than the expression of thyroid autoimmunity.

Quercetin decreases proliferation of orbital fibroblasts and their release of hyaluronic acid.

BACKGROUND: Inhibition of fibroblast (FB) proliferation and hyaluronic acid (HA) production may be a therapeutic approach to Graves' ophthalmopathy (GO). The flavonoid quercetin has a wide range of activities, including reduction of FB growth. AIM: To investigate the effects of quercetin in orbital FB from GO patients and control subjects. METHODS: Primary cultures of orbital FB were treated with quercetin or with its glycosides rutin and quercitrin. Cell proliferation, necrosis, apoptosis, HA production, and cell cycle were measured. RESULTS: Beginning at a 30 µM concentration, quercetin, but not rutin and quercitrin, reduced cell proliferation, with no difference between GO and control FB. The effect of quercetin on proliferation was due to necrosis and cell cycle blockade, whereas apoptosis was unaffected. Quercetin reduced HA in the cell media, with no difference between GO and control FB. CONCLUSIONS: Quercetin reduces cell proliferation and HA release in orbital FB. Whether these initial findings have any potential for the use of quercetin in the clinical practice remains to be established.

Lateral wall orbital decompression in Graves' orbitopathy.

Orbital decompression can be carried out, for rehabilitative reasons, using various techniques, but a general consensus on the ideal surgical approach has not been reached. Postoperative diplopia is the most common side effect of decompression surgery. The authors report 39 patients (72 orbits) who underwent lateral wall orbital decompression. Mean preoperative and postoperative Hertel exophthalmometry were 22.8+/-2.2mm (mean+/-SD; range 16-26 mm) and 18.2+/-2.1mm (range 15-22 mm), respectively. Mean proptosis reduction was 4.5+/-1.9 mm. A new appearance of diplopia postoperatively in the extreme gaze direction was observed in three patients (8%). The complication rate in this series was low, making the procedure safe and well tolerated. In the authors' opinion, when a single-wall approach is feasible, lateral wall decompression should be the first choice because of its effectiveness in terms of proptosis reduction and safeness in terms of postoperative diplopia.

Outcome of orbital decompression for disfiguring proptosis in patients with Graves' orbitopathy using various surgical procedures.

AIM: To compare the outcome of various surgical approaches of orbital decompression in patients with Graves' orbitopathy (GO) receiving surgery for disfiguring proptosis. METHOD: Data forms and questionnaires from consecutive, euthyroid patients with inactive GO who had undergone orbital decompression for disfiguring proptosis in 11 European centres were analysed. RESULTS: Eighteen different (combinations of) approaches were used, the swinging eyelid approach being the most popular followed by the coronal and transconjunctival approaches. The average proptosis reduction for all decompressions was 5.0 (SD 2.1) mm. After three-wall decompression the proptosis reduction was significantly greater than after two-wall decompression. Additional fat removal resulted in greater proptosis reduction. Complications were rare, the most frequent being worsening of motility, occurring more frequently after coronal decompression. The average change in quality of life (QOL) in the appearance arm of the GO-QOL questionnaire was 20.5 (SD 24.8) points. CONCLUSIONS: In Europe, a wide range of surgical approaches is used to reduce disfiguring proptosis in patients with GO. The extent of proptosis reduction depends on the number of walls removed and whether or not fat is removed. Serious complications are infrequent. Worsening of ocular motility is still a major complication, but was rare in this series after the swinging eyelid approach.

Autoimmune hepatitis during intravenous glucocorticoid pulse therapy for Graves' ophthalmopathy treated successfully with glucocorticoids themselves.

We report a case of acute hepatitis of autoimmune origin which occurred in a 43-yr-old woman during iv glucocorticoid (GC) pulse therapy for Graves' ophthalmopathy (GO). Prior to therapy, liver function tests were normal with no previous history of liver disorders or conditions predisposing to GC-associated liver damage. After the administration of a 4.7-g cumulative dose of methylprednisolone acetate, there was a marked increase of liver enzymes, prompting immediate discontinuation of iv GC. Nevertheless, liver enzymes increased further, reaching a peak 45 days later, with values 30- to 50-fold greater than those prior to therapy, associated with evidence of impaired liver function. Liver biopsy showed a marked lymphocytic infiltration, likely indicating an autoimmune hepatitis. Based on the assumption that following GC-induced immune suppression, autoimmune hepatitis might have been precipitated by sudden re-activation of the immune system during interpulse periods, we treated the patient with im and then oral GC, in order to re-induce immune suppression. Within three days from re-institution of GC therapy, there was a marked reduction of liver enzymes and amelioration of liver function. Complete normalization was achieved two months later, while the patient was still receiving a low maintenance dose of oral prednisone.

Failure to use measurement of megalin secretory components complexed with serum thyroglobulin as a tool to identify metastases after surgery in papillary thyroid cancer.

When thyroid follicles are intact, some colloidal thyroglobulin (Tg) reaches the circulation by megalin-mediated transcytosis and is to various extents complexed with megalin secretory components. In contrast, in papillary thyroid cancer (PTC), serum Tg is not complexed with megalin because it is directly secreted by tumor cells. Here we attempted to use measurement of megalin secretory components to distinguish PTC patients with thyroid remnant plus metastases from those with thyroid remnant only, after thyroidectomy and before 131I ablation. Tg values in anti-Tg antibodies (TgAb)-free sera from 5 PTC patients with thyroid remnant plus metastases and 12 PTC patients with thyroid remnant only were measured following pre-adsorption with uncoupled protein A beads or with protein A beads coupled with antimegalin antibodies. The degree of Tg pre-adsorption with antimegalin antibodies was minimal, with no substantial differences between the two groups. Thus, we concluded that measurement of megalin secretory components is unlikely to be useful to identify the origin of serum Tg in PTC patients after thyroidectomy.

Role of thyroglobulin in the pathogenesis of Graves' ophthalmopathy: the hypothesis of Kriss revisited.

One of the hypothesis to explain the pathogenesis of Graves' ophthalmopathy (GO) was formulated by Joseph P. Kriss in the early 1970s. He postulated that the initiating event in the pathogenesis of GO is the deposition and accumulation of thyroglobulin (Tg) in orbital tissues, followed by an autoimmune reaction against Tg. In the last 30 yrs several studies have addressed this hypothesis, through various, different experimental approaches, raising results that are both in favor and against the possibility that Tg plays a role in the pathogenesis of GO. The finding that intact Tg is present in orbital tissues of GO patients supports Kriss' hypothesis, although the role of Tg as an autoantigen seems to be unlikely, as GO is not significantly associated with serum TgAb and mice immunized with Tg do not develop GO. Whether Tg is indeed involved in the pathogenesis of GO remains to be established. Our current view is that, provided that Tg plays a role, it is unlikely the only factor involved and Tg in orbital tissues may rather reinforce or worsen a damage initiated by other mechanisms.

Impaired thyroglobulin (Tg) secretion by FRTL-5 cells transfected with soluble receptor associated protein (RAP): evidence for a role of RAP in the Tg biosynthetic pathway.

Secretion of thyroglobulin (Tg) by thyrocytes requires several endoplasmic reticulum (ER)-resident molecular chaperones. The receptor-associated protein (RAP), a known molecular chaperone, binds to Tg in thyroid cells shortly after biosynthesis. Here we investigated whether RAP is involved in Tg secretion by FRTL-5 cells. For this purpose, we studied Tg secretion by FRTL-5 cells transfected with a soluble RAP chimera, as a mean for interfering with endogenous RAP. We used a RAP-human IgG Fc (RAP-Ig) chimeric cDNA, which was designed in order to exclude the ER retention sequence of RAP and to allow generation of a secreted form of RAP. FRTL-5 cells were transiently transfected with the RAP-Ig cDNA or, as control, with a CD8-Ig cDNA. Media were collected at 24, 48 and 72 h after transfection. Secretion of fusion proteins and of Tg in the media was measured by ELISA. As expected, under standard culture conditions, RAP was not secreted into the media by FRTL-5 cells, even though it could be detected by Western blotting in cell extracts. In transfection experiments, fusion proteins were present in the media of FRTL-5 cells transfected with either RAP-Ig or CD8-Ig, indicating that transfection was successful. Although Tg was found in the media of FRTL-5 cells transfected with either CD8-Ig or RAP-Ig, a lower amount was found in cells transfected with RAP-Ig. Therefore, we concluded that RAP is involved in Tg secretion by FRTL-5 cells suggesting that RAP may function as a Tg molecular chaperone.