Biochemical evidence of hyperthyroidism is frequently encountered in hyperemesis gravidarum, but its relationship to the cause of hyperemesis is unknown. We studied the relationship of serum hCG, thyroid function, and severity of vomiting among 57 hyperemesis patients and 57 controls matched for gestational age. TSH was suppressed in 60% of hyperemesis patients and 9% of controls. hCG correlated directly with free T4(r = 0.45, P < 0.001) and inversely with TSH (r = -0.48, P < 0.001). Hyperemesis patients had significantly greater mean serum hCG, free T4, total T3, and estradiol, and lesser serum TSH compared to controls. Hyperemesis patients with suppressed TSH had significantly greater free T4 and hCG compared to those with TSH in the normal range. Control and hyperemesis subjects were divided into four groups based on the severity of vomiting. The degree of biochemical hyperthyroidism and hCG concentration varied directly with the severity of vomiting. Unextracted serum was tested for thyrotropic activity by measuring its effect on iodide uptake in cultured FRTL-5 rat thyroid cells. Thyrotropic activity correlated with serum hCG (r = 0.50, P < 0.001). These data show that biochemical hyperthyroidism is a common finding in patients with hyperemesis gravidarum and suggest that hCG is the thyroid stimulator in this state. The increased estradiol concentration in patients with hyperemesis gravidarum may be attributed to the effects of hCG on steroidogenesis.

Administration of recombinant human tumor necrosis factor-alpha (TNF) to rats and mice produces a model of nonthyroid illness in which there is impairment of hypothalamic-pituitary thyroid function, including reduced serum concentrations of T4 and T3, reduced thyroid radioiodine uptake, and reduced response to TSH. In this study, we tested the binding and effects of TNF on FRTL-5 cells and on four human thyroid carcinoma cell lines. The TSH-stimulated [125I]iodide uptake by FRTL-5 cells was inhibited by TNF in a dose-dependent manner. The four human thyroid carcinoma cell lines (NPA, MRO, ARO, WRO) have TSH receptors but did not respond to TSH in regard to iodide uptake and thymidine incorporation. Both human thyroid carcinoma cells and FRTL-5 cells contain specific receptors for TNF. Scatchard analysis showed that the receptor numbers and dissociation constants in human thyroid carcinoma cells and FRTL-5 cells were, respectively; 2.4 x 10(4), 5.4 nM (WRO); 8 x 10(3), 3.4 nM (MRO); 4 x 10(3), 1 nM (ARO); 7 x 10(3), 1 nM (NPA); 3 x 10(3), 1 nM (FRTL-5), and 9 x 10(3), 1 nM (FRTL-5 cells treated with TSH). The results indicate that TNF affects thyroid cell function through binding to the TNF receptor and that the number of TNF receptors is regulated by TSH.

hCG stimulates thyroid function, but it has been suggested that it is impurities in commercial hCG preparations or a variant of hCG that are responsible for the thyrotropic activity. In this study, we tested the thyrotropic activity of purified and commercial hCG and compared its action with that of bovine TSH (bTSH) in cultured rat FRTL-5 cells in regard to stimulation of iodide uptake, activation of adenylate cyclase, and synthesis of DNA. Iodide uptake was measured after incubation of the cells for 48-72 h with the test hormones, followed by a 40-min incubation with 0.1 microCi Na125I and 10 mumol/L carrier NaI; the 125I in the washed cells was counted. Adenylate cyclase was measured after incubation of the cells with the test stimulators for 3 h in hypotonic medium by RIA of cAMP in the medium. DNA synthesis was measured after incubation of the cells with the test substances for 24 h, followed by addition of [3H]thymidine for 3 h and then measuring the incorporation of [3H]thymidine into the cells. Both purified and commercial hCG produced a dose-related increase in iodide uptake. The relative potency of commercial hCG was 0.024 microU bTSH/U hCG and that of purified hCG was 0.042 microU bTSH/U hCG; compared with human TSH, the potency of purified hCG was 0.72 microU/U hCG. hCG caused a dose-related increment of adenylate cyclase and [3H]thymidine incorporation. The effect of hCG on iodide uptake and [3H]thymidine incorporation was additive with that of bTSH; hCG was not an antagonist of TSH in these cultured rat thyroid cells. We conclude that hCG has intrinsic thyrotropic activity in FRTL-5 cells in regard to stimulation of iodide uptake, activation of adenylate cyclase, and stimulation of DNA synthesis.

It is well known that peptide heterogeneity exists in the hCG-beta subunit in pregnancy and in patients with trophoblastic diseases. To elucidate the differences in thyrotropic activity of hCG molecules, we examined cAMP accumulation and TSH receptor binding of intact hCG, hLH, and a recombinant hCG that lacked the C-terminal extension on the beta-subunit, hCG (alpha wt/beta delta T), using Chinese hamster ovary (CHO) cells transfected with hTSH receptors. hLH, which shares 85% sequence identity with the hCG-beta molecule except for the C-terminal amino acid residue extension of the hCG-beta subunit, bound to the TSH receptor and stimulated adenylate cyclase about 10 times more potently than hCG on a molar basis. This was consistent with the result that cAMP stimulation by mutant hCG (alpha wt/beta delta T) was greater than intact hCG. hLH also increased iodide uptake and thymidine incorporation in FRTL-5 rat thyroid cells more potently than intact hCG. These results demonstrate that hLH is a more potent TSH than hCG and that the C-terminal extension of the hCG beta-subunit can interfere with hCG interaction with the hTSH receptor. hCG lacking the C-terminal extension of the beta-subunit occurs in the mixture of heterogeneous hCG molecular forms of pregnancy and trophoblastic diseases and may contribute to the hyperthyroidism in patients with hydatidiform mole, choriocarcinoma, and hyperemesis gravidarum.

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Previous work showed that treatment of rats with tumour necrosis factor-\g=a\ produced a model of nonthyroid illness in which there was reduction of circulating thyroid hormones and TSH, reduced thyroid response to TSH, and reduced thyroid iodide uptake. In vitro studies showed that tumour necrosis factor-\g=a\ binds to a specific receptor on FRTL-5 rat thyroid cells, that TSH increases the number of tumour necrosis factor-\g=a\ receptors, and that tumour necrosis factor-\g=a\ inhibits iodide uptake by these cells. In the present study, we obtained additional data on the effects of tumour necrosis factor-\g=a\ on FRTL-5 cells and studied the mechanism of action of tumour necrosis factor-\g=a\ in these cells. Tumour necrosis factor-\g=a\ inhibited both basal and TSH-stimulated [125I]iodide uptake; tumour necrosis factor-\g=a\ slowed the recovery of [125I]iodide trapping after the cells were exposed to TSH and augmented the loss of the [125I]iodide trapping function after the cells were deprived of TSH; tumour necrosis factor-\g=a\ inhibited[125I]iodide trapping in a noncompetitive manner; tumour necrosis factor-\g=a\ did not affect cell growth of FRTL-5 cells. Interleukin-1 (IL-1) also inhibited basal and TSH-stimulated [125I]iodide uptake, but it stimulated cell growth. Tumour necrosis factor-\g=a\ and IL-1 did not affect the generation of cAMP in the presence or absence of TSH; these cytokines blocked the cAMP-induced stimulation of [125I]iodide uptake. Tumour necrosis factor-\g=a\ did not affect [3H]arachidonic acid uptake or release by FRTL-5 cells. The inhibitors of the phospholipase A2\ x=r eq-\ arachidonic acid pathway did not affect the action of tumour necrosis factor-\g=a\. The H2O2 scavenger, catalase, did not block the action of tumour necrosis factor-\g=a\. The results show that both tumour necrosis factor-\g=a\ and IL-1 inhibit FRTL-5 function and that the site of action of these cytokines is distal to the production of cAMP. The actions of tumour necrosis factor-\g=a\ on FRTL-5 cells do not appear to be mediated by the phospholipase A2-arachidonic acid pathway or by H2O2.Tumour necrosis factor-a (TNF) and interleukin 1 (IL-1) are very important mediators in inflamma¬ tory processes. The biological actions of these cy¬ tokines in vivo and in vitro have received much attention recently (1-3). These cytokines may be responsible for changes of thyroid function in nonthyroid illness, such as infections. Studies in an¬ imals have shown that TNF and IL-1 treatment causes reduction of circulating thyroid hormones, thyrotropin, reduced thyroid [l2T]iodide uptake, and reduced thyroid response to TSH (4-7). FRTL-5 rat thyroid cells have TNF receptors (8). The number of TNF receptors is upregulated by TSH, but TNF does not affect TSH binding to the TSH receptor. TNF treatment causes inhibition of TSH stimulated [12T]iodide uptake by the FRTL-5 cells (7,8). Recent reports showed that the mRNAs of TNF and IL-1 are synthesized at considerable levels even in normal tissues (9). This suggests that TNF and II-1 may h...

We recently reported that tumor necrosis factor-alpha (TNF-alpha) induction of the synthesis and secretion of transforming growth factor (TGF)-beta 1 by FRTL-5 cells is a thyroid-stimulating hormone (TSH)-dependent and age-dependent process. TNF-alpha is only cytotoxic to aged (> 40 passages) FRTL-5 cells grown in TSH-containing medium, whereas TGF-beta induces programmed cell death (apoptosis) in epithelial cells but not in FRTL-5 cells, which otherwise retain many properties of normal thyroid follicular cells. This cell line is, therefore, a convenient model for studies on the TSH-dependent and age-dependent inhibitory effects of these cytokines on epithelial cell growth, viability, and function. One prominent effect of TNF-alpha (and TGF-beta 1) on FRTL-5 cell function is suppression of iodide uptake, which is markedly stimulated by TSH. In aged FRTL-5 cells, iodide uptake is only about 10% that of young control cells. Na+/K(+)-ATPase activity, which drives iodide uptake by thyroid cells, is inhibited by TNF-alpha and TGF-beta. The following experiments quantitate the effects of TSH, aging, TNF-alpha, and TGF-beta 1 on the expression and activity of Na+/K(+)-ATPase activity in FRTL-5 cells. Young (< 20 passages) and aged (> 40 passages) FRTL-5 cells were treated with various doses (0-100 ng/ml) of recombinant human TNF-alpha or TGF-beta 1 for various times (0-3 days) with and without 2 U/liter TSH. These treatments reduced the rate-limiting Na+/K(+)-ATPase beta 1 mRNA level and Na+/K(+)-ATPase activity in parallel in a dose-dependent and time-dependent fashion. Aged FRTL-5 cells were more sensitive to the inhibitory effects of TNF-alpha, whereas young cells were more sensitive to the suppressive effects of TGF-beta 1 on the expression and activity of Na+/K(+)-ATPase. We conclude that inhibition of Na+/K(+)-ATPase activity by TNF-alpha and TGF-beta in FRTL-5 cells is differentially affected by aging and that this inhibitory effect can be dissociated from effects on cell viability.

hCG is known to have thyroid-stimulating activity and may cause hyperthyroidism in patients with trophoblastic diseases. hCG occurs in normal and molar pregnancy with breaks or nicks in the alpha- or beta-subunit peptide linkage and with substantial heterogeneity in the composition and degree of branching within the oligosaccharide side-chains. The bioactivity of hCG is markedly influenced by these structural variations. We purified hCG from five hydatidiform moles, using chromatofocusing separation after gel filtration. The hCG molecules were fractionated according to their isoelectric points, with a linear pH gradient from 3.2-6.1 and a final 1.0 mol/L NaCl step elution. The hCG immunoreactivity of each fraction was measured by RIA, and the thyroid-stimulating activity of hCG was determined by means of the cAMP response in Chinese hamster ovary cells expressing functional human TSH receptors (Chinese hamster ovary-JP09 cells). The chromatofocusing profile showed that hCG from the moles was eluted in six or seven major peaks at pH 6.1, 5.5, 5.3, 4.8, 3.8, and 3.2 and with 1.0 mol/L NaCl, whereas hCG extracted from serum of hydatidiform moles and standard hCG preparation CR-127 extracted from pregnancy urine showed only small peaks at pH greater than 5.3. Each fraction increased cAMP production significantly in Chinese hamster ovary-JP09 cells. The relative bioactivity/immunoreactivity, represented as the ratio of cAMP/hCG (picomoles per IU), was significantly higher in basic components (pI 6.1, 6.2 +/- 1.2; pI 5.5, 4.4 +/- 2.7; pI 5.3, 5.8 +/- 0.3) than in hCG CR-127 (bioactivity/immunoreactivity, 0.42; P < 0.05). The difference in pI of each hCG isoform was attributable to the extent of sialylation; basic hCG isoforms contained less sialic acid by immunological detection using lectins. These results indicate that isoforms of hCG with more thyrotropic activity were produced by trophoblastic tissues in patients with hydatidiform mole. We speculate that these isoforms of hCG may be responsible for the hyperthyroidism in some patients with hydatidiform moles.