Targeted expression of the human thyrotropin receptor A-subunit to the mouse thyroid: insight into overcoming the lack of response to A-subunit adenovirus immunization

The thyrotropin receptor (TSHR), the major autoantigen in Graves' disease, is posttranslationally modified by intramolecular cleavage to form disulfide-linked A- and B-subunits. Because Graves' hyperthyroidism is preferentially induced in BALB/c mice using adenovirus encoding the free A-subunit rather than full-length human TSHR, the shed A-subunit appears to drive the disease-associated autoimmune response. To further investigate this phenomenon, we generated transgenic mice with the human A-subunit targeted to the thyroid. Founder transgenic mice had normal thyroid function and were backcrossed to BALB/c. The A-subunit mRNA expression was confirmed in thyroid tissue. Unlike wild-type littermates, transgenic mice immunized with low-dose A-subunit adenovirus failed to develop TSHR Abs, hyperthyroidism, or splenocyte responses to TSHR Ag. Conventional immunization with A-subunit protein and adjuvants induced TSHR Abs lacking the characteristics of human autoantibodies. Unresponsiveness was partially overcome using high-dose, full-length human TSHR adenovirus. Although of low titer, these induced Abs recognized the N terminus of the A-subunit, and splenocytes responded to A-subunit peptides. Therefore, "non-self" regions in the B-subunit did not contribute to inducing responses. Indeed, transgenic mice immunized with high-dose A-subunit adenovirus developed TSHR Abs with thyrotropin-binding inhibitory activity, although at lower titers than wild-type littermates, suggesting down-regulation in the transgenic mice. In conclusion, in mice expressing a human A-subunit transgene in the thyroid, non-self human B-subunit epitopes are not necessary to induce responses to the A-subunit. Our findings raise the possibility that autoimmunity to the TSHR in humans may not involve epitopes on a cross-reacting protein, but rather, strong adjuvant signals provided in bystander immune responses.     

Breaking Tolerance in Transgenic Mice Expressing the Human TSH Receptor A-Subunit: Thyroiditis, Epitope Spreading and Adjuvant as a 'Double Edged Sword'

Transgenic mice with the human thyrotropin-receptor (TSHR) A-subunit targeted to the thyroid are tolerant of the transgene. In transgenics that express low A-subunit levels (Lo-expressors), regulatory T cell (Treg) depletion using anti-CD25 before immunization with adenovirus encoding the A-subunit (A-sub-Ad) breaks tolerance, inducing extensive thyroid lymphocytic infiltration, thyroid damage and antibody spreading to other thyroid proteins. In contrast, no thyroiditis develops in Hi-expressor transgenics or wild-type mice. Our present goal was to determine if thyroiditis could be induced in Hi-expressor transgenics using a more potent immunization protocol: Treg depletion, priming with Complete Freund's Adjuvant (CFA) + A-subunit protein and further Treg depletions before two boosts with A-sub-Ad. As controls, anti-CD25 treated Hi- and Lo-expressors and wild-type mice were primed with CFA+ mouse thyroglobulin (Tg) or CFA alone before A-sub-Ad boosting. Thyroiditis developed after CFA+A-subunit protein or Tg and A-sub-Ad boosting in Lo-expressor transgenics but Hi- expressors (and wild-type mice) were resistant to thyroiditis induction. Importantly, in Lo-expressors, thyroiditis was associated with the development of antibodies to the mouse TSHR downstream of the A-subunit. Unexpectedly, we observed that the effect of bacterial products on the immune system is a "double-edged sword". On the one hand, priming with CFA (mycobacteria emulsified in oil) plus A-subunit protein broke tolerance to the A-subunit in Hi-expressor transgenics leading to high TSHR antibody levels. On the other hand, prior treatment with CFA in the absence of A-subunit protein inhibited responses to subsequent immunization with A-sub-Ad. Consequently, adjuvant activity arising in vivo after bacterial infections combined with a protein autoantigen can break self-tolerance but in the absence of the autoantigen, adjuvant activity can inhibit the induction of immunity to autoantigens (like the TSHR) displaying strong self-tolerance.     

Schistosoma mansoni and alpha-galactosylceramide: prophylactic effect of Th1 Immune suppression in a mouse model of Graves' hyperthyroidism

Graves' hyperthyroidism, an organ-specific autoimmune disease mediated by stimulatory thyrotropin receptor (TSHR) autoantibodies, has been considered a Th2-dominant disease. However, recent data with mouse Graves' models are conflicting. For example, we recently demonstrated that injection of BALB/c mice with adenovirus coding the TSHR induced Graves' hyperthyroidism characterized by mixed Th1 and Th2 immune responses against the TSHR, and that transient coexpression of the Th2 cytokine IL-4 by adenovirus skewed Ag-specific immune response toward Th2 and suppressed disease induction. To gain further insight into the relationship between immune polarization and Graves' disease, we evaluated the effect of Th2 immune polarization by helminth Schistosoma mansoni infection and alpha-galactosylceramide (alpha-GalCer), both known to bias the systemic immune response to Th2, on Graves' disease. S. mansoni infection first induced mixed Th1 and Th2 immune responses to soluble worm Ags, followed by a Th2 response to soluble egg Ags. Prior infection with S. mansoni suppressed the Th1-type anti-TSHR immune response, as demonstrated by impaired Ag-specific IFN-gamma secretion of splenocytes and decreased titers of IgG2a subclass anti-TSHR Abs, and also prevented disease development. Similarly, alpha-GalCer suppressed Ag-specific splenocyte secretion of IFN-gamma and prevented disease induction. However, once the anti-TSHR immune response was fully induced, S. mansoni or alpha-GalCer was ineffective in curing disease. These data support the Th1 theory in Graves' disease and indicate that suppression of the Th1-type immune response at the time of Ag priming may be crucial for inhibiting the pathogenic anti-TSHR immune response.     

A novel murine model of Graves' hyperthyroidism with intramuscular injection of adenovirus expressing the thyrotropin receptor

In this work we report a novel method to efficiently induce a murine model of Graves' hyperthyroidism. Inbred mice of different strains were immunized by i.m. injection with adenovirus expressing thyrotropin receptor (TSHR) or beta-galactosidase (1 x 10(11) particles/mouse, three times at 3-wk intervals) and followed up to 8 wk after the third immunization. Fifty-five percent of female and 33% of male BALB/c (H-2(d)) and 25% of female C57BL/6 (H-2(b)) mice developed Graves'-like hyperthyroidism with elevated serum thyroxine (T(4)) levels and positive anti-TSHR autoantibodies with thyroid-stimulating Ig (TSI) and TSH-binding inhibiting Ig (TBII) activities. In contrast, none of female CBA/J (H-2(k)), DBA/1J (H-2(q)), or SJL/J (H-2(s)) mice developed Graves' hyperthyroidism or anti-TSHR autoantibodies except SJL/J, which showed strong TBII activities. There was a significant positive correlation between TSI values and T(4) levels, but the correlations between T(4) and TBII and between TSI and TBII were very weak. TSI activities in sera from hyperthyroid mice measured with some chimeric TSH/lutropin receptors suggested that their epitope(s) on TSHR appeared similar to those in patients with Graves' disease. The thyroid glands from hyperthyroid mice displayed diffuse enlargement with hypertrophy and hypercellularity of follicular epithelia with occasional protrusion into the follicular lumen, characteristics of Graves' hyperthyroidism. Decreased amounts of colloid were also observed. However, there was no inflammatory cell infiltration. Furthermore, extraocular muscles from hyperthyroid mice were normal. Thus, the highly efficient means that we now report to induce Graves' hyperthyroidism in mice will be very useful for studying the pathogenesis of autoimmunity in Graves' disease.     

Prevention of autoantibody-mediated Graves'-like hyperthyroidism in mice with IL-4, a Th2 cytokine

Graves' hyperthyroidism has long been considered to be a Th2-type autoimmune disease because it is directly mediated by autoantibodies against the thyrotropin receptor (TSHR). However, several lines of evidence have recently challenged this concept. The present study evaluated the Th1/Th2 paradigm in Graves' disease using a recently established murine model involving injection of adenovirus expressing the TSHR (AdCMVTSHR). Coinjection with adenovirus expressing IL-4 (AdRGDCMVIL-4) decreased the ratio of Th1/Th2-type anti-TSHR Ab subclasses (IgG2a/IgG1) and suppressed the production of IFN-gamma by splenocytes in response to TSHR Ag. Importantly, immune deviation toward Th2 was accompanied by significant inhibition of thyroid-stimulating Ab production and reduction in hyperthyroidism. However, in a therapeutic setting, injection of AdRGDCMVIL-4 alone or in combination with AdCMVTSHR into hyperthyroid mice had no beneficial effect. In contrast, coinjection of adenoviruses expressing IL-12 and the TSHR promoted the differentiation of Th1-type anti-TSHR immune responses as demonstrated by augmented Ag-specific IFN-gamma secretion from splenocytes without changing disease incidence. Coinjection of adenoviral vectors expressing IL-4 or IL-12 had no effect on the titers of anti-TSHR Abs determined by ELISA or thyroid-stimulating hormone-binding inhibiting Ig assays, suggesting that Ab quality, not quantity, is responsible for disease induction. Our observations demonstrate the critical role of Th1 immune responses in a murine model of Graves' hyperthyroidism. These data may raise a cautionary note for therapeutic strategies aimed at reversing Th2-mediated autoimmune responses in Graves' disease in humans.     

An edited linkage map for the AXB and BXA recombinant inbred mouse strains

We have updated the history of the AXB and BXA recombinant inbred (RI) strains, typed additional loci, and edited the AXB, BXA RI database. Thirteen of the original 51 AXB and BXA RI strains are either extinct or genetically contaminated, leaving 33 living strains available from The Jackson Laboratory. However, we found a high degree of similarity among three sets of strains, indicating that these strains are not independent, which leaves 27 independent RI strains in the set. Accordingly, we modified the database by combining the AXB and BXA RI sets and eliminating strains that were genetically contaminated or extinct with no available DNA. We added 92 newly typed loci, retyped some questionable genotypings, and removed loci with excessive double crossovers or an insufficient number of typed strains. The edited strain distribution pattern (SDP) is available on the World Wide Web (WWW) (http://www.informatics.jax.org/riset.html) and now includes over 700 loci. Each locus is linked to adjacent loci with a LOD score of at least 3.0 with a few described exceptions. We also carried out a second editing designed for the analysis of quantitative trait loci by deleting extinct strains and loci with identical SDPs; this edited database is also available on the WWW. Received: 20 March 1998 / Accepted: 26 May 1998     

Pathogenesis of thyroid eye disease - does autoimmunity against the TSH receptor explain all cases?

Thyroid associated ophthalmopathy, or thyroid eye disease (TED), is a complex inflammatory disorder of the eye that, as its name implies, is usually associated with thyroid disease. Clinical observation supports the existence of three main TED subtypes, namely ocular myopathy, congestive myopathy, and mixed congestive and myopathic ophthalmopathy. Although the precise pathophysiology of TED remains unclear, it is likely to reflect an autoimmune reaction involving sensitised T lymphocytes and autoantibodies directed against a specific orbital or thyroid-and-orbital shared antigen(s). One well-studied candidate in this immune reaction is the thyroid-stimulating hormone receptor (TSHR), which is also expressed in the orbital fibroblast and preadipocyte. Most patients with ophthalmopathy have associated Graves' disease, 10% have Hashimoto's thyroiditis in which the eye changes are often mild and expressed mainly as upper eyelid retraction (UER), and 10% have no apparent associated thyroid disease - so-called "euthyroid Graves' disease". Ophthalmopathy can also occur in some patients with transient thyroiditis, thyroid cancer, and Graves' disease many years after treatment of the hyperthyroidism - situations where TSHR antibodies are not expected to be present, suggesting that the relationship between TSHR antibodies and the eye disorder has not been established for all cases. In our studies of TED we have investigated the nature and significance of antibodies targeting other eye muscle and orbital connective tissue (OCT) antigens, in particular the calcium binding protein calsequestrin (CASQ1) and the orbital fibroblast membrane antigen collagen XIII. Our working hypotheses for the pathogenesis of TED are: i) the initial reaction in the orbit is antibody and T lymphocyte targeting of the TSHR in the OCT compartment, and ii) the associated extra ocular and upper eyelid muscle inflammation reflects either autoimmunity against primary skeletal muscle antigens such as CASQ1 or a secondary, non specific effect of the OCT reactions as proposed by the main proponents of the "TSHR hypothesis". Here, we review the evidence that autoimmunity against the TSHR expressed in the orbit can be implicated in the development of all cases of TED. Although there is a close general correlation between ophthalmopathy and TSHR antibodies there are many exceptions, suggesting that the continued study of the possible role of autoimmunity against calsequestrin and collagen XIII is justified.     

Continuously increasing sensitivity over three generations of TSH receptor autoantibody assays

Thyroid stimulating hormone (TSH) receptor (TSHR) antibodies (TRAb) are the hallmarks in serological diagnosis of Graves' disease (GD, autoimmune hyperthyroidism). In the 1980s, the first generation liquid-phase TRAb assay with detergent solubilized porcine TSHR was introduced into routine thyroid serology and proved to be highly specific for GD, albeit with moderate sensitivity. In the 1990 s, second generation solid-phase TRAb assays with immobilized porcine or recombinant human TSHR became available, and were clearly more sensitive for Graves' disease without loss of specificity. Recently, third generation TRAb assays have been developed, in which the human thyroid stimulating monoclonal antibody M22 replaces bovine TSH as the competing reagent for TRAb binding to TSHR. Again, an improvement in functional sensitivity was reported for this latest assay generation. To investigate the analytical (aas) and functional assay sensitivity (fas) over 3 generations of TRAb assays, pooled serum samples from patients with GD were measured 10-fold in different assay lots over a few months. The 20% inter-assay coefficients of variation (CV) were calculated and compared taking into account the different calibrations of the assay generations. The fas continuously increased from about 8 U/l of MRC B65/122 in liquid phase TRAb assays, to about 1.0 IU/l (NIBSC 90/672) in TSH based solid phase TRAb assays and to about 0.3 IU/l (NIBSC 90/672) in the M22 based TRAb assay finally. In conclusion, the fas of TRAb measurements has been improved continuously over the last 3 decades.     

Strain distribution pattern in AXB and BXA recombinant inbred strains for loci on murine Chromosomes 10, 13, 17, and 18

Strain distribution patterns (SDPs) of selected loci previously mapped to murine Chromosomes (Chrs) 10, 13, 17, and 18 are reported for the AXB, BXA recombinant inbred (RI) strain set derived from the progenitor strains A/J (A) and C57BL/6J (B). The loci included the simple sequence length polymorphisms (D10Nds1, D10Mit2, D10Mit10, D10Mit14, D13Mit3, D13Nds1, D13Mit10, D13Mit13, D13Mit7, D13Mit11, D17Mit18, D17Mit10, D17Mit20, D17Mit3, D17Mit2, D18Mit17, D18Mit9, and D18Mit4), the restriction fragment length polymorphisms Pdea and Csfmr, and the biochemical marker AS-1. These loci were chosen because they map to genomic regions that had few or no genetic markers in the AXB, BXA RI set. Several of these loci also were typed in backcross progeny of matings of the (AXB)F₁ to strain A or B. The strain distribution patterns for chromosomes 10, 13, 17, and 18 are reported, and the gene order and map distances determined from the backcross data. The addition of these markers to the AXB, BXA RI strain set increases the genomic region over which linkage for new markers can be detected.     

The AXB and BXA set of recombinant inbred mouse strains

The recombinant inbred (RI) set of strains, AXB and BXA, derived from C57BL/6J and A/J, originally constructed and maintained at the University of California/San Diego, have been imported into The Jackson Laboratory and are now in the 29th to 59th generation of brother-sister matings. Genetic quality control testing with 45 proviral and 11 biochemical markers previously typed in this RI set indicated that five strains had been genetically contaminated sometime in the past, so these strains have been discarded. The correct and complete strain distribution patterns for 56 genetic markers are reported for the remaining RI strain set, which consists of 31 living strains and 8 extinct strains for which DNA is available. Two additional strains, AXB 12 and BXA 17, are living and may be added to the set pending further tests of genetic purity. The progenitors of this RI set differ in susceptibility to 27 infectious diseases as well as atherosclerosis, obesity, diabetes, cancer, cleft palate, and hydrocephalus. Thus, the AXB and BXA set of RI strains will be useful in the genetic analysis of several complex diseases.     

Similarity and dissimilarity between clinical and laboratory findings, especially anti-thyrotropin receptor antibody in ophthalmic Graves' disease without persistent hyperthyroidism and hyperthyroid Graves' disease

The aim of this study was to investigate thyroid states, significance of anti-TSH receptor antibodies and the clinical courses of patients with euthyroid Graves' ophthalmopathy. The clinical and laboratory finding of 30 patients with euthyroid Graves' ophthalmopathy were briefly as follows: 1) normal sized thyroid or small goiter; 2) negative or weakly positive thyrotropin binding inhibitor immunoglobulin (TBII); 3) normal thyroid [99 m-Tc] pertechnetate uptake; and 4) frequent observations of low serum TSH values. Besides TBII, thyroid stimulating antibody (TSAb) was measured under low salt and isotonic conditions using FRTL-5 rat thyroid cells. Both TBII and TSAb titers were lower in euthyroid Graves' ophthalmopathy than in hyperthyroid Graves' disease. Serum TSH levels frequently became low in patients considered as euthyroid upon the first examination as well as in Graves' patients in remission, reflecting preceding or mild hyperthyroidism. In follow-up studies, these patients with mildly elevated thyroid hormone levels and low TSH levels seldom reached a state of persistent hyperthyroidism, when TBII was negative or only weakly positive.     

Prokaryotic expression of the thyrotropin receptor and identification of an immunogenic region of the protein using synthetic peptides

Graves' disease is characterized by hypersecretion of thyroid hormones due to binding of autoantibodies to the thyrotropin receptor (TSHR). In order to study immunological aspects of the TSHR we expressed the extracellular domain of the rat TSHR (ETSHR) as a fusion protein with beta-galactosidase in a prokaryotic system. The identity of this ETSHR-fusion protein was confirmed by Western blot, using antibodies to synthetic peptides derived from TSHR. Patients' sera reacted to a significantly greater extent with the affinity purified ETSHR relative to control sera. Similarly, sera from patients with Graves' disease displayed significant reactivity with only one of five peptides, RH2 (residues 352-366), when compared with normal sera. These data, together with the predicted hydrophilicity of the peptide RH2, suggest that amino acids 352-366 which lie within one of the unique regions of the extracellular domain of the TSHR may be important for antibody binding.     

New murine polymorphisms detected by random amplified polymorphic DNA (RAPD) PCR and mapped by use of recombinant inbred strains

Oligonucleotide primers of random sequence that were 12 bases in length, 58% in GC content, and lacking internal palindromes were designed. By random amplified polymorphic DNA (RAPD) PCR, these primers were used to survey for DNA variations between the progenitors of the mouse AXB and BXA recombinant inbred sets (A/J and C57BL/6J). We identified 17 DNA variants detected by 10 primers. Map positions for these variants were determined by comparing their strain distribution patterns in the AXB, BXA recombinant inbred sets with strain distribution patterns of previously published loci. When necessary, BXD and NXSM recombinant inbred sets were also used. These 17 new loci mapped to 12 chromosomes. The 10 primers were also used to survey 20 inbred mouse strains including the progenitors of other recombinant inbred sets and four mouse strains recently inbred from the wild (CAST/Ei, MOLF/Ei, PERA/Ei, and SPRET/Ei).     

Cleavage of the human thyrotropin receptor by ADAM10 is regulated by thyrotropin

The thyrotropin receptor (TSHR) has a unique 50 residue (317-366) ectodomain insertion that sets it apart from other glycoprotein hormone receptors (GPHRs). Other ancient members of the leucine-rich repeat G protein-coupled receptor (GPCR) (LGR) family do exhibit ectodomain insertions of variable lengths and sequences. The TSHR-specific insert is digested, apparently spontaneously, to release the ectodomain (A-subunit) leaving the balance of the ectodomain attached to the serpentine (B-subunit). Despite concerted efforts for the last 12 years by many laboratories, the enzyme involved in TSHR cleavage has not been identified and a physiologic role for this process remains unclear. Several lines of evidence had suggested that the TSHR protease is likely a member of the a disintegrin and metalloprotease (ADAM) family of metalloproteases. We show here that the expression of ADAM10 was specific to the thyroid by specially designed DNA microarrays. We also show that TSH increases TSHR cleavage in a dose-dependent manner. To prove that ADAM10 is indeed the TSHR cleavage enzyme, we investigated the effect of TSH-induced cleavage by a peptide based on a motif (TSHR residues 334-349), shared with known ADAM10 substrates. TSH increased dose dependently TSHR ectodomain cleavage in the presence of wild-type peptide but not a scrambled control peptide. Interestingly, TSH increased the abundance of non-cleaved single chain receptor, as well higher molecular forms of the A-subunit, despite their enhancement of the appearance of the fully digested A-subunit. This TSH-related increase in TSHR digested forms was further increased by wild-type peptide. We have identified for the first time ADAM10 as the TSHR cleavage enzyme and shown that TSH regulates its activation.     

Autoantibodies interacting with purified native thyrotropin receptor.

Native thyrotropin receptor (TSHR) was purified by immunoaffinity chromatography from membrane extracts of stably transfected L cells. An ELISA test was devised to study anti-TSHR autoantibodies directly. Comparison of native TSHR with bacterially expressed, denatured TSHR showed that the latter was not recognized by the autoantibodies, suggesting that they bind to conformational epitopes only present on the native receptor. The use of deglycosylated TSHR and of purified receptor ectodomain (alpha-subunit) showed that the autoantibodies recognized only the protein backbone moiety of the receptor and that their epitopes were localized entirely in its ectodomain. Autoantibodies were detected in 45 of 48 subjects with untreated Graves' disease and in 26 of 47 healthy volunteers. The affinity for the receptor was similar in the two groups (Kd = 0.25-1 x 10-10 M) and the autoantibodies belonged to the IgG class in all cases. Although the concentration of autoantibodies was higher in Graves' disease patients (3.50 +/- 0.36 mg.L-1) than in control subjects (1.76 +/- 0.21) (mean +/- SEM), there was an overlap between the groups. Receptor-stimulating autoantibodies (TSAb) were studied by measuring cAMP synthesis in stably transfected HEK 293 cells. Their characteristics (recognition of alpha-subunit, of deglycosylated TSHR, nonrecognition of bacterially expressed denatured receptor) were similar to those of the antibodies detected by the ELISA test. TSAb were only found in individuals with Graves' disease. The ELISA test measures total anti-TSHR antibodies, whereas the test using adenylate cyclase stimulation measures antibodies that recognize specific epitopes involved in receptor activation. Our observations thus disprove the hypothesis according to which Graves' disease is related to the appearance of anti-TSHR antibodies not present in normal subjects. Actually, anti-TSHR antibodies exist in many euthyroid subjects, in some cases even at concentrations higher than those found in patients with Graves' disease. What distinguishes the latter from normal subjects is the existence of subpopulation(s) of antibodies directed against specific epitope(s) of the receptor involved in its activation.     

Etiopathogenesis of Graves' disease

Graves' disease is an autoimmune disorder, caused by thyroid-stimulating antibodies, which bind to and activate the thyrotropin receptor on thyroid cells, inducing the synthesis and release of thyroid hormones. It is a polygenic and multifactorial disease that develops as a result of complex interaction between genetic susceptibility and environmental and/or endogenous factors. Graves' disease differs from other autoimmune diseases of the thyroid by specific clinical features, including hyperthyroidism, vascular goitre, ophthalmopathy and--less commonly--infiltrative dermopathy. This article discusses current theories, regarding the etiology and pathogenesis of Graves' disease, including possible predisposing factors, autoimmune aspects of Graves' disease, ophthalmopathy, and dermopathy.     

Absence of IL-4, and not suppression of the Th2 response,prevents development of experimental autoimmune Graves' disease

In autoimmune Graves' disease (GD), autoantibodies bind to the thyrotropin receptor (TSHR) and cause hyperthyroidism. We studied the effects of fms-like tyrosine kinase receptor 3 ligand (Flt3-L) or GM-CSF treatment on the development of experimental autoimmune GD (EAGD) in mice, a slowly progressing Ab-mediated organ-specific autoimmune disease of the thyroid induced by immunization with syngeneic cells expressing TSHR. Flt3-L and GM-CSF treatment resulted in up-regulation of CD8a(+) and CD8a(-) dendritic cells, and skewing of cytokine and immune responses to TSHR in favor of Th1 and Th2, respectively. However, this skewing did not persist until the later stages, and thus failed to affect the course or severity of the disease. To determine whether the total absence of either IL-4 or IFN-gamma could affect the development of EAGD, we immunized wild-type, IFN-gamma(-/-) and IL-4(-/-) BALB/c mice with TSHR. Nearly 100% of the wild-type and IFN-gamma(-/-) mice developed EAGD with optimal TSHR-specific immune responses, while IL-4(-/-) mice completely resisted disease and showed delayed and suboptimal pathogenic Ab response. These data demonstrated that skewing immune responses to TSHR, using either Flt3-L or GM-CSF, in favor of Th1 or Th2, respectively, may not be sufficient to alter the course of the disease, while the complete absence of IL-4, but not IFN-gamma, can prevent the development of EAGD.     

Congenital hyperthyroidism: the fetus as a patient

Congenital hyperthyroidism is less frequent than congenital hypothyroidism but its impact on growth and development can be as dramatic. The immune form of hyperthyroidism that is transmitted from a mother with Graves' disease to her foetus and then neonate is transient, but cases of persistent congenital hyperthyroidism had also been described, that can now be explained by molecular abnormalities of the thyrotropin receptor. The abundance of published data on the neonatal effects of maternal Graves' disease contrasts with the paucity of information on fetal effects. Recent studies showed that it is of utmost to scrutinize fetal thyroid by expert ultrasonographist and to have a team work with obstetricians and pediatric endocrinologists in pregnant women with Graves' disease. This allowed to accurately determine the fetal thyroid status and to adapt the treatment in the mothers successfully. Fetal hyperthyroidism does exist and needs an appropriate aggressive treatment. Clearly the fetus has become our patient!     

Independent quantitative trait loci influence ventral and dorsal hippocampal volume in recombinant inbred strains of mice

Anatomical and functional studies support segregation of the hippocampus into ventral and dorsal components along its septotemporal axis. However, it is unknown whether the development of these two components of the hippocampus is influenced by common or separate genetic factors. In this study, we used recombinant inbred strains of mice to determine whether the same or different quantitative trait loci (QTL) influence ventral and dorsal hippocampal volume. Using two sets of strains of recombinant inbred mice (BXD and AXB/BXA), we identified separate QTLs for ventral and dorsal hippocampal volume. In BXD mice, suggestive QTLs for ventral hippocampus were identified on chromosomes 2, 8 and 13, and a significant QTL for dorsal hippocampal volume was identified on chromosome 15. There was also a suggestive QTL for dorsal hippocampal volume on chromosome 13. In AXB/BXA mice, there were no significant or suggestive QTLs for ventral hippocampal volume, but a significant QTL for dorsal hippocampus was identified on chromosome 5. These findings suggest that the development of the ventral and dorsal components of the hippocampus is influenced by separate genetic loci.