| Wakelkamp et al., Amsterdam, The Netherlands, determined orbital expression and TSH-R mRNA in orbital fat and connective tissue obtained during decompressive surgery of 6 untreated patients with active GO and 11 patients with inactive GO. They found that TSH-R mRNA was present in 5/6 active GO and 2/11 inactive GO. Furthermore in active GO, mRNA levels of pro-inflammatory cytokines (IL-1 b, IL-6, IL-8, and IL-10) were higher than in inactive GO while Th1 cytokine expression IFN a and IL-12 also tended to be higher in active GO. Th2 cytokine expression was similar in both groups and TSH-R mRNA was almost exclusively found in active GO. The authors conclude that expression of the TSH receptor at the transscriptional level is only observed in the active stage of the disease and lost in the inactive stage. Cytokine expression in both GO stages is different and may be used for selection of immunomodulatory treatment. (Comment: The temporary expression of TSH-R is remarkable and its significance as to the cause of the disease warrants further study). Simonetta et al., Pisa, Italy, studied the distribution of thyroglobulin in orbital tissues from patients with OG. They did this because several decades ago Kriss et al. hypothesized that retrograde transported Tg via the lymphatics could move to retro-orbital tissues and in this way act as an autoantigen in the pathogenesis of GO. The present authors took this issue up again and found that in extracts of orbital tissues from patients with a GO in 3/7 cases using immunoprecipitation, and in 4/7 cases using ELISA, Tg was found in retrobulbar fibroadipose tissue and in inflamed palpebral skin. In addition, ELISA Tg was also found in extraocular muscles. The authors feel that these results support the previously forwarded hypothesis by Kriss et al, in that Tg may act as a co-antigen in the pathogenesis of GO (Comment: Is Tg also present in the same tissues of control patients?). |
