Quantification of cells expressing the thyrotropin receptor in extraocular muscles in thyroid associated orbitopathy.
OBJECTIVE
Thyroid associated orbitopathy (TAO) and Graves' disease (GD) have an autoimmune pathogenesis, possibly related to the thyrotropin receptor (TSHR). The aim of this study was to determine whether TSHR immunoreactivity is correlated with disease severity or serum TSHR antibody (TRAB) levels.


METHODS
Orbital tissues from 30 patients with TAO were compared with those of 20 patients with strabismus and four with non-thyroid orbital inflammation. TSHR was detected by immunohistochemistry and TRAB were measured by radioreceptor assay.


RESULTS
No TSHR immunoreactivity was detected in the 24 control orbital tissues, whereas in all TAO biopsies elongated fibroblast-like cells, expressing TSHR, were present. These cells were located between the muscle cells, which were separated by oedema in the acute phase but fibrous tissue in the chronic phase of disease. Semi-thin sections showed numerous mast cells present in the chronic phase and in close contact with adipocytes. The number of TSHR immunostained cells was high in early disease, decreased with disease duration, and was positively correlated with TRAB levels at the onset of TAO.


CONCLUSIONS
TSHR immunoreactivity was demonstrated specifically in TAO orbits which highlights the importance of TRAB early in the pathogenesis.
Boschi
A
A
Department of Ophthalmology, Université Catholique de Louvain, Avenue Hippocrate 10, B-1200 Brussels, Belgium. boschi@ofta.ucl.ac.be
Daumerie
Ch
Ch
Spiritus
M
M
Beguin
C
C
Senou
M
M
Yuksel
D
D
Duplicy
M
M
Costagliola
S
S
Ludgate
M
M
Many
M C
MC
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001323:Autoantibodies / Q000097:blood; D001327:Autoimmune Diseases / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D001706:Biopsy; D018450:Disease Progression; D005260:Female; D006111:Graves Disease / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D007124:Immunoenzyme Techniques; D008297:Male; D008875:Middle Aged; D009801:Oculomotor Muscles / Q000378:metabolism* / Q000473:pathology; D009915:Orbit / Q000378:metabolism / Q000473:pathology; D009916:Orbital Diseases / Q000276:immunology / Q000378:metabolism*; D011989:Receptors, Thyrotropin / Q000276:immunology / Q000378:metabolism*; D012720:Severity of Illness Index; D013967:Thyroiditis, Autoimmune / Q000276:immunology / Q000378:metabolism / Q000473:pathology
D001323:Autoantibodies; D011989:Receptors, Thyrotropin