No abstract

Both smoking and thyroid dysfunction are frequent in the general population. Many studies have shown that cigarette smoking interferes with thyroid function and with the evolution of thyroid pathology (e.g. goiter formation and thyroid cancer development). Some studies have also suggested a significant correlation of Graves' hyperthyroidism and Graves' ophthalmopathy with the severity of smoking. In addition, cigarette smoking may reduce the effectiveness of some therapeutic modalities, such as orbital radiotherapy or high-dose systemic glucocorticoid administration for severe thyroid eye disease. Tobacco smoking seems to induce similar changes in thyroid function in the adult and the fetus. This review article discusses the effect of cigarette smoking on thyroid function and morphology as well as on thyroid autoimmunity.

Cytokines are likely to play an important role in auto¬ immune thyroid disease. These molecules are produced by both inflammatory cells and thyroid follicular cells and may affect the latter directly including expression of major histocompatibility complex class II molecules and adhesion mol¬ ecules (1-9).Interleukin-8 (IL-8) is a cytokine with neutrophil chemotactic/activating and T-cell chemotactic activity both in vivo and in vitro (10,11)· It is synthesized as a 99-amino acid pre¬ cursor and secreted as a 72-amino acid peptide after succes¬ sive removal of aminoterminal residues. Its known actions include chemotaxis and activation of neutrophils, expression of surface adhesion molecules on neutrophils, angiogenesis (12) and mitogenesis of epidermal (13), melanoma (14), and vascular smooth muscle cells (15). IL-8 has not been investi¬ gated in depth in autoimmune thyroid diseases in humans. We quantitated IL-8 levels in patients with Graves' disease, toxic nodular goiter, and Hashimoto's thyroiditis.We studied 30 thyrotoxic patients (TP) all with elevated free thyroxine (FT4) and suppressed thyrotropin (TSH) lev¬ els (9 males and 21 females; mean age 42.3 ± 11.1; range, 24-65), 20 of whom (6 males and 14 females) had Graves' disease (GD) and 10 toxic nodular goiter (TNG). Patients with GD were identified by the presence of one or more of the following: diffuse uptake of thyroid with 99-technetium scanning, positive thyroid antibodies, and signs of thyroid eye disease. We also studied 16 patients with Hashimoto's thyroiditis (HT), (4 males and 12 females; mean age 52.0 ± 13.8; range, 19-77), all with elevated TSH (> 9 µ /mL) and positive thyroid antibodies. Fifteen normal individuals of similar age and gender were used as controls (C).In all patients and controls, IL-8 levels were measured, for which a competitive enzyme-linked immunosorbent assay was used. This assay measures the total amount of free and bound cytokine in serum.The lower limit of detection was 10 pg/mL. All results are expressed as mean ± SD. Data were compared with Stu¬ dent's unpaired t test and correlations between variables within groups were tested by Pearson's correlation test, < 0.05 was accepted as significant.Our results indicated that although mean levels of IL-8 were higher in TP in comparison with C (50.97 ± 42.14 vs. 37.17 ± 41.63) this difference was not statistically significant, most probably due to the high SD. A positive correlation was found between mean IL-8 values and FT4 (p = 0.005). No dif¬ ferences were found in IL-8 levels between GD and TNG subgroups (49.91 ± 41.3 vs. 53.09 ± 45.94), as well as be¬ tween these subgroups and C (49.91 ± 41.3 vs. 37.17 ± 41.63 and 53.09 ± 45.94 vs. 37.17 ± 41.63). No differences were found between TP and HT groups (50.97 ± 42.14 vs. 40.20 ± 29.87). Also, no differences were quantitated concerning IL-8 levels between male and female patients when compared with C (46.08 ± 20.28 vs. 37.17 ± 41.63 and 53.06 ± 48.95 vs. 37.17 ± 41.63, respectively). As far as the HT patients are concerned, w...