Biomedical subjects

A Weetman

Publications and source records attributed to A Weetman.

10 recordsLinked to original sources

PubMed2002

The incidence of thyroid abnormalities in adults irradiated for lymphoma.

The aim of the study was to investigate the incidence of thyroid abnormalities in neck irradiated lymphoma patients. Of the 298 patients who had irradiation to the neck for lymphoma between 1966-1988, 174 were found to be alive and free of disease. These patients were invited to participate in the study. From the 174, 93 were able to participate (group 1). Two control groups were recruited; both were sex and aged matched. One group (group 2) consisted of lymphoma patients who were treated with chemotherapy (n=39) or irradiation to areas other than the neck (n=16). The other group (group 3) consisting of healthy volunteers (n=35) recruited from hospital staff and minor surgery attendees, had never had lymphoma or radiotherapy. All participants were required to complete a past medical history and thyroid symptom questionnaire, had blood taken for assays of thyroid stimulating hormone (TSH), thyroglobulin antibodies, thyroid peroxidase antibodies, sodium iodide symporter antibodies and TSH receptor antibodies and underwent ultrasound and clinical examination of the neck. A significant percentage of patients who had been irradiated in the neck had abnormalities on ultrasound, compared to groups 2 and 3 (77% vs 42% vs 24%). Abnormal TSH levels were found to be significantly more common in neck irradiated patients compared to the other groups (50% vs 9% vs 5%). There is a clear difference between neck irradiated patients and control groups. The importance of screening irradiated patients for thyroid abnormalities is re-emphasised.

Adult↗

PubMed1999

Pulsed monoclonal antibody treatment and autoimmune thyroid disease in multiple sclerosis.

BACKGROUND: Multiple sclerosis results from T-cell-dependent inflammatory demyelination of the central nervous system. Our objective was long-term suppression of inflammation with short-term monoclonal antibody treatment. METHODS: We depleted 95% of circulating lymphocytes in 27 patients with multiple sclerosis by means of a 5-day pulse of the humanised anti-CD52 monoclonal antibody, Campath-1H. Clinical and haematological consequences of T-cell depletion, and in-vitro responses of patients' peripheral-blood mononuclear cells were analysed serially for 18 months after treatment. FINDINGS: Radiological and clinical markers of disease activity were significantly decreased for at least 18 months after treatment. However, a third of patients developed antibodies against the thyrotropin receptor and carbimazole-responsive autoimmune hyperthyroidism. The depleted peripheral lymphocyte pool was reconstituted with cells that had decreased mitogen-induced proliferation and interferon gamma secretion in vitro. INTERPRETATION: Campath-1H causes the immune response to change from the Th1 phenotype, suppressing multiple sclerosis disease activity, but permitting the generation of antibody-mediated thyroid autoimmunity.

Adult↗

PubMed1999

Contrasting effects of activating mutations of GalphaS and the thyrotropin receptor on proliferation and differentiation of thyroid follicular cells.

The cyclic AMP pathway is a major regulator of thyrocyte function and proliferation and, predictably, its inappropriate activation is associated with a sub-set of human thyroid tumours. Activating mutations are, however, more common in the thyrotropin receptor (TSHR) than in its downstream transducer, Galphas. To investigate whether this reflects an inherent difference in their oncogenic potency, we compared the effects of retrovirally-transduced mutant (A623I) TSHR or (Q227L) Galphas (GSP), using the rat thyroid cell line FRTL5 and primary human thyrocytes. In FRTL5, expression of GSP or mutant (m) TSHR induced a 2 - 3-fold increase in basal levels of cAMP. This was associated with TSH-independent proliferation (assessed by both cell number and DNA synthesis) and function (as shown by increased expression of thyroglobulin (Tg) and the sodium/iodide symporter). In primary cultures, expression of mTSHR, but not GSP, consistently induced formation of colonies with epithelial morphology and thyroglobulin expression, capable of 10 - 15 population doublings (PD) compared to less than three in controls. Thus, while mTSHR and GSP exert similar effects in FRTL5, use of primary cultures reveals a major difference in their ability to induce sustained proliferation in normal human thyrocytes, and provides the first direct evidence that mTSHR is sufficient to initiate thyroid tumorigenesis.

Animals↗

PubMed1999

Multicenter study on TGPO autoantibody prevalence in various thyroid and non-thyroid diseases; relationships with thyroglobulin and thyroperoxidase autoantibody parameters.

OBJECTIVE: TGPO autoantibodies (aAbs) that bind simultaneously to thyroglobulin (Tg) and thyroperoxidase (TPO) are present in the serum of patients with autoimmune thyroid diseases (AITD) and have been found to differ from monospecific Tg and TPO aAbs. To obtain further insights on the prevalence defined as the rate of occurrence and significance of TGPO aAbs in a large population, we carried out a collaborative study involving 15 European teams. METHODS: Serum samples from 3122 patients with various thyroid and non-thyroid diseases and normal subjects were assayed using a novel TGPO aAb detection kit. This test was designed so that TGPO aAbs are trapped between the Tg-coated solid phase and the soluble TPO labeled with a radioiodinated monoclonal antibody. RESULTS: Only three out of the 220 normal subjects (prevalence of 1.4%) were found to have positive TGPO aAb levels, which were mainly observed in the patients with AITD: the group of patients suffering from Hashimoto's thyroiditis had a TGPO aAb prevalence of 40.5% (n=437 patients), those with Graves' disease, a prevalence of 34.6% (n=645) and those with post-partum thyroiditis, 16.0% (n=243). Among the non-AITD patients with positive TGPO aAb levels, the TGPO aAb prevalence ranged from 20.7% among those with thyroid cancer (n=246) to 0% among those with toxic thyroid nodules (n=47). Among the patients with non-thyroid diseases, the TGPO aAb prevalence ranged from 9.8% in the case of Biermer's pernicious anemia (n=78) to 0% in that of premature ovarian failure (n=44). It is worth noting that the groups showing the highest TGPO aAb prevalence also contained the patients with the highest TGPO aAb titers. Statistical comparisons between the TGPO aAb prevalences in the various groups showed that TGPO aAb could be used as a parameter to distinguish between the groups of Hashimoto's and Graves' patients and between the women with post-partum thyroiditis and the post-partum women with only Tg and/or TPO aAb established during early pregnancy. Unexpectedly, the correlations between TGPO aAbs and Tg and TPO aAbs were found to depend mainly on the assay kit used. CONCLUSION: High TGPO aAb titers are consistently associated with AITD but the reverse was not found to be true. TGPO aAbs are a potentially useful tool, however, for establishing Hashimoto's diagnosis, and would be worth testing in this respect with a view to using them for routine AITD investigations.

Autoantibodies↗

PubMed1998

The thyrotropin receptor in thyroid eye disease.

Thyroid eye disease (TED) has an autoimmune etiology, but the nature of the autoantigen that is the target of the initiating event remains unknown. A number of candidates have been proposed based on Western blotting, library screening, and deduction from sequence similarity. A strong favorite is the thyrotropin receptor (TSHR), which is the target of the thyroid stimulating antibodies (TSAB) of Graves' disease (GD). We have recently demonstrated TSHR transcripts in orbital adipose tissue from a patient with TED by Northern blot, transcripts in normal adipose tissue being at the limit of detection. We have shown that the transcripts are translated into protein by immunohistochemical analysis using two monoclonal antibodies to the TSHR generated by genetic immunization. TSHR immunoreactivity is associated with elongated cells with the appearance of a fibroblast, often adjacent to clusters of adipocytes, in orbital biopsies from patients with TED but not in strabismus or pseudotumor biopsies. In animal studies, we have transferred thyroiditis to naive BALBc and NOD mice, using T cells primed to the human TSHR, either using the receptor expressed as a bacterial fusion protein or by genetic immunization. The BALBc develop a Th2-type response to the receptor, but the NOD a Th1-type with thyrocyte destruction. Orbital pathology, edema, infiltration by mast cells and lymphocytes, and adipose accumulation was also induced in 68% of the BALBc but none of the NOD mice. Together these data indicate that the preadipocyte expresses the TSHR and that a Th2 autoimmune response to the receptor may be an initiating event in TED.

Animals↗

PubMed1998

Somatic hypermutation in autoimmune thyroid disease.

Autoimmune thyroid disease is one of the most common autoimmune diseases. There is typically patient antibody (Ab) reactivity to one or more of the antigens thyroglobulin (Tg), thyroid peroxidase (TPO) and the thyroid simulating hormone receptor (TSHr). With the advent of combinatorial library technology, there has been an enormous increase in the number of sequences from Ab to Tg and TPO. The repertoire of both Tg and TPO Ab is restricted and indicates the importance of somatic hypermutation in the development of the high affinity Ab response. However, there are still too few sequences to determine patterns in which the mutation occurs, which residues are introduced during substitution and how individual substitutions affect the affinity of the Ab. Ab to the TSHr are of far greater pathological significance than those to Tg and TPO, but the current repertoire of Ab to the TSHr has yet to include the high affinity IgG Ab characteristic of patient serum Ab. Instructive analysis of the role of somatic hypermutation in the development of TSHr Ab therefore still awaits the isolation of the pathologically active repertoire. Despite this, the Ab response in thyroid autoimmunity remains one of the best characterised of human autoimmune diseases.

Amino Acid Sequence↗

PubMed1998

Common mutations in autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy patients of different origins.

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED; OMIM *240300, also called APS 1,) is a rare autosomal recessive disorder that is more frequent in certain isolated populations. It is generally characterized by two of the three major clinical symptoms that may be present, Addison's disease and/or hypoparathyroidism and/or chronic mucocutaneous candidiasis. Patients may also have a number of other clinical symptoms including chronic gastritis, gonadal failure, and rarely, autoimmune thyroid disease and insulin-dependent diabetes mellitus. We and others have recently identified the gene for APECED, which we termed AIRE (for autoimmune regulator). AIRE is expressed in thymus, lymph nodes, and fetal liver and encodes a protein containing motifs suggestive of a transcriptional regulator, including two zinc finger motifs (PHD finger), a proline-rich region, and three LXXLL motifs. Six mutations, in cluding R257X, the predominant Finnish APECED allele, have been defined. R257X was also observed in non-Finnish APECED patients occurring on different chromosomal haplotypes suggesting different mutational origins. Here we present mutation analyses in an extended series of patients, mainly of Northern Italian origin. We have detected 12 polymorphisms, including one amino acid substitution, and two additional mutations, R203X and X546C, in addition to the previously described mutations, R257X, 1096-1097insCCTG, and a 13-bp deletion (1094-1106del). R257X was also the common mutation in the Northern Italian patients (10 of 18 alleles), and 1094-1106del accounted for 5 of 18 Northern Italian alleles. Both R257X and 1094-1106del were both observed in patients of four different geo-ethnic origins, and both were associated with multiple different haplotypes using closely flanking polymorphic markers showing likely multiple mutation events (six and four, respectively). The identification of common AIRE mutations in different APECED patient groups will facilitate its genetic diagnosis. In addition, the polymorphisms presented provide the tools for investigation of the involvement of AIRE in other autoimmune diseases, particularly those affecting the endocrine system.

Female↗

PubMed1997

Antigen presentation by epithelial cells induces anergic immunoregulatory CD45RO+ T cells and deletion of CD45RA+ T cells.

The immunoregulatory effects of alloantigen presentation by tissue parenchymal cells to resting peripheral blood CD4+ T cells was investigated. Coculture of CD45RO+ (memory) and CD45RA+ (naive) T lymphocytes with primary cultures of MHC class II-expressing epithelial cells rendered both populations of T cells hyporesponsive to a subsequent challenge by the same MHC molecule expressed on EBV-transformed lymphoblastoid B cell lines. However, the mechanisms responsible for the allospecific hyporesponsiveness were distinct. For the CD45RO+ T cells, responsiveness was restored by subsequent culture in the presence of IL-2; the addition of IL-2 had no effect on the reactivity of the CD45RA+ T cells. In contrast, the naive T cells were protected from the induction of nonresponsiveness by the presence of a neutralizing anti-CD95 Ab during the culture with thyroid follicular cells. In addition, the hyporesponsive CD45RO+ T cells effected linked suppression, in that they inhibited proliferation against a third-party DR alloantigen when the third-party alloantigen was coexpressed with the DR Ag against which hyporesponsiveness had been induced. These results suggest that recognition of Ag by T cells on tissue parenchymal cells plays an important role in the maintenance of peripheral T cell tolerance, inducing nonresponsiveness in naive and memory T cells by distinct mechanisms.

Animals↗

PubMed1997

Antigen presentation by interferon-gamma-treated thyroid follicular cells inhibits interleukin-2 (IL-2) and supports IL-4 production by B7-dependent human T cells.

The consequence of recognition of antigen on antigen-presenting cells that are induced to express major histocompatibility complex (MHC) class II molecules following an inflammatory process is still not clear. In this study, we have investigated the outcome of antigen presentation by epithelial cells and we have used as a model thyroid follicular cells (TFC) that are known to express MHC class II molecules in autoimmune thyroid diseases and acquire the capacity to present autoantigens to T cells infiltrating the thyroid gland. The result show that MHC class II-expressing TFC were unable to stimulate a primary T cell alloresponse, using CD4+ T cells from three HLA-mismatched responders. Phenotypic analysis showed that TFC, after incubation with interferon-gamma, do not express the costimulatory molecules B7-1 (CD80) and -2 (CD86). Addition of murine DAP.3 cells expressing human B7-1 (DAP.3-B7) to cultures containing peripheral blood CD4+ T cells and DR1-expressing TFC led to a proliferative response, suggesting that the failure of TFC to stimulate a primary alloresponse was due to a lack of co-stimulation. Similarly, HLA-DR-restricted, influenza-specific T cell clones dependent on B7 for co-stimulation did not respond to peptide presented by TFC; again the lack of response could be overcome by co-culture of TFC with DAP.3-B7. Furthermore, recognition of antigen on TFC inhibited interleukin-2 (IL-2) production in the B7-dependent T cells. In contrast, in T helper type 0 (Th0) T cells, IL-4 release was not affected by TFC presentation. In addition, antigen presentation by TFC favored IL-4 production relative to IL-2 production by B7-independent Th0 clones. These results suggest that antigen presentation by MHC class II+ TFC may induce tolerance in autoreactive Th1 cells but may simultaneously favors a Th2 response in uncommitted T cells, and thereby support autoantibody production.

Adult↗

PubMed1994

Presence of nonfunctional thyrotropin receptor variant transcripts in retroocular and other tissues.

The TSH receptor (TSHR) has been proposed as an antigenic link between the thyroid and the orbit; TSHR transcripts have been demonstrated by other groups, one in orbital tissue and the other in orbital and dermal fibroblasts. In a previous study we were unable to demonstrate transcripts for the complete TSHR in retroocular muscle containing also fibroblasts. We now confirm this finding. A 1.3-kilobase variant of the TSHR messenger ribonucleic acid (mRNA) has been described in normal and Graves' thyroids; it contains exons 1-8 of the major mRNA species and a unique 3'-sequence predicted to encode further amino acids and a polyadenylated tail. Lacking the membrane-spanning region, the corresponding variant protein, if expressed, is not expected to couple to G-proteins. Using primers specific for this variant in reverse polymerase chain reaction experiments, Southern blotting and frequencies, we demonstrate the presence of this transcript in normal and Graves' thyroid, extraocular muscle, peripheral blood mononuclear cells, and, to a lesser extent, in fat and fibroblasts. TSH-mediated protein synthesis, cAMP, and glycosaminoglycan production have been measured in cultured fibroblasts. At 5 mU/mL, bovine TSH stimulated glycosaminoglycan production, but recombinant TSH did not, even at higher concentrations, suggesting that contaminating factors are responsible. Together the data do not support the presence of a functional complete TSHR in orbital tissue. However, they are compatible with a role for the extracellular portion of the receptor as a nonfunctional autoantigen and provide some explanation for the conflicting results with regard to the relevance of the TSHR in the pathophysiology of thyroid-associated ophthalmopathy.

Actins↗