Chronic Estradiol Exposure Modulates Thyroid Structure and Decreases T4 and T3 Serum Levels in Middle-Aged Female Rats

Relationship between thyroid function and sex hormones in female German shepherd dogs

BACKGROUND

Several variables influence the serum concentration of thyroid hormones in dogs, including breed, age, drugs, and concurrent diseases. However, data regarding the interaction between thyroid function and the estrous stage of female dogs are limited.

HYPOTHESIS

Estrous stage may influence thyroid function in German Shepherd dogs.

METHODS

Longitudinal, observational, non-randomized cohort study. The dogs were monitored during the complete estrous cycle, and different stages were determined by vaginal cytology. Two blood samples were collected at the beginning and end of each stage to analyze the following: total thyroxine (TT4), free thyroxine (fT4), total triiodothyronine (TT3), free triiodothyronine (fT3), canine thyrotropin (cTSH), progesterone, 17-β-estradiol, triglycerides, and cholesterol concentrations. Hematological and biochemical evaluations were performed at the beginning and end of the study period.

ANIMALS

Seventeen German Shepherds were included, of which 7 were bred during the study period. One dog was excluded for estrus interruption and another for suspected hypothyroidism.

RESULTS

Serum concentrations of T4, fT4, and fT3 were negatively correlated with age. Total thyroxine demonstrated significant changes in serum concentrations between estrous stages, with higher concentrations in estrus and diestrus. Total thyroxine concentrations were positively correlated with progesterone concentrations and negatively correlated with 17-β-estradiol concentrations. Free thyroxine did not show significant variations but was positively correlated with progesterone concentrations. Canine TSH concentrations were positively correlated with 17-β-estradiol concentrations. No significant differences in thyroid hormones and cTSH concentrations were observed between diestrus during pregnancy and pseudopregnancy.

CONCLUSIONS

Different stages of estrus can influence the measurement of TT4 in female dogs.

Extensive and Persistent Extravascular Dermal Fibrin Deposition Characterizes Systemic Sclerosis

Systemic sclerosis (SSc) is an autoimmune disease characterized by progressive multiorgan fibrosis. While the cause of SSc remains unknown, a perturbed vasculature is considered a critical early step in the pathogenesis. Using fibrinogen as a marker of vascular leakage, we found extensive extravascular fibrinogen deposition in the dermis of both limited and diffuse systemic sclerosis disease, and it was present in both early and late-stage patients. Based on a timed series of excision wounds, retention on the fibrin deposit of the splice variant domain, fibrinogen αEC, indicated a recent event, while fibrin networks lacking the αEC domain were older. Application of this timing tool to SSc revealed considerable heterogeneity in αEC domain distribution providing unique insight into disease activity. Intriguingly, the fibrinogen-αEC domain also accumulated in macrophages. These observations indicate that systemic sclerosis is characterized by ongoing vascular leakage resulting in extensive interstitial fibrin deposition that is either continually replenished and/or there is impaired fibrin clearance. Unresolved fibrin deposition might then incite chronic tissue remodeling.

A New Perspective on Thyroid Hormones: Crosstalk with Reproductive Hormones in Females

Accumulating evidence has shown that thyroid hormones (THs) are vital for female reproductive system homeostasis. THs regulate the reproductive functions through thyroid hormone receptors (THRs)-mediated genomic- and integrin-receptor-associated nongenomic mechanisms, depending on TH ligand status and DNA level, as well as transcription and extra-nuclear signaling transduction activities. These processes involve the binding of THs to intracellular THRs and steroid hormone receptors or membrane receptors and the recruitment of hormone-response elements. In addition, THs and other reproductive hormones can activate common signaling pathways due to their structural similarity and shared DNA consensus sequences among thyroid, peptide, and protein hormones and their receptors, thus constituting a complex and reciprocal interaction network. Moreover, THs not only indirectly affect the synthesis, secretion, and action of reproductive hormones, but are also regulated by these hormones at the same time. This crosstalk may be one of the pivotal factors regulating female reproductive behavior and hormone-related diseases, including tumors. Elucidating the interaction mechanism among the aforementioned hormones will contribute to apprehending the etiology of female reproductive diseases, shedding new light on the treatment of gynecological disorders.

Differential expression and interaction of melatonin and thyroid hormone receptors with estrogen receptor α improve ovarian functions in letrozole-induced rat polycystic ovary syndrome

AIMS

The objective of the present study was to investigate the effect of melatonin and L-thyroxine (T4) on the expression of various receptors, and some metabolic, reproductive, and gonadotropic hormones in letrozole-induced polycystic ovary syndrome (PCOS) in rats.

MATERIAL AND METHODS

Assessment of gravimetric, hormonal profile and thyroid histology and relative expression of melatonin receptors (MT1, MT2) and estrogen receptor α (Erα) in thyroid and ovary, and type II iodothyronine deiodinase (Dio2) and thyroid hormone receptor α (TRα) in ovary were done according to standard protocols.

KEY FINDINGS

A significant increase in thyroid follicles numbers was noted in the hyperthyroid rat. T4 treatment to PCOS showed the expected increment in the circulating level of triiodothyronine (T) and T₄. Melatonin and T4 treatment of PCOS rats resulted in a significant decrease in the circulating level of T₃ and T₄. Hyperthyroid rats showed a decrement in plasma melatonin levels. However, T4 treatment to PCOS rats showed increased circulating melatonin levels, and a decrease in the circulating level of gonadotropins (LH and FSH), and testosterone. Melatonin treatment to PCOS-hyperthyroid rats resulted in the normal expression of ovarian and thyroid MT1 and ERα, receptors, which had been altered in PCOS and hyperthyroid rats, without any significant change in the MT2 receptor.

SIGNIFICANCE

The present findings suggest a fine interplay and cross-talk via melatonin and its two receptors with ERα, TRα, and Dio₂ in thyroid and ovarian tissue during PCOS and hyperthyroidism pathogenicity.

Global skin gene expression analysis of early diffuse cutaneous systemic sclerosis shows a prominent innate and adaptive inflammatory profile

OBJECTIVES

Determine global skin transcriptome patterns of early diffuse systemic sclerosis (SSc) and how they differ from later disease.

METHODS

Skin biopsy RNA from 48 patients in the Prospective Registry for Early Systemic Sclerosis (PRESS) cohort (mean disease duration 1.3 years) and 33 matched healthy controls was examined by next-generation RNA sequencing. Data were analysed for cell type-specific signatures and compared with similarly obtained data from 55 previously biopsied patients in Genetics versus Environment in Scleroderma Outcomes Study cohort with longer disease duration (mean 7.4 years) and their matched controls. Correlations with histological features and clinical course were also evaluated.

RESULTS

SSc patients in PRESS had a high prevalence of M2 (96%) and M1 (94%) macrophage and CD8 T cell (65%), CD4 T cell (60%) and B cell (69%) signatures. Immunohistochemical staining of immune cell markers correlated with the gene expression-based immune cell signatures. The prevalence of immune cell signatures in early diffuse SSc patients was higher than in patients with longer disease duration. In the multivariable model, adaptive immune cell signatures were significantly associated with shorter disease duration, while fibroblast and macrophage cell type signatures were associated with higher modified Rodnan Skin Score (mRSS). Immune cell signatures also correlated with skin thickness progression rate prior to biopsy, but did not predict subsequent mRSS progression.

CONCLUSIONS

Skin in early diffuse SSc has prominent innate and adaptive immune cell signatures. As a prominently affected end organ, these signatures reflect the preceding rate of disease progression. These findings could have implications in understanding SSc pathogenesis and clinical trial design.

Blockade of CCL24 with a monoclonal antibody ameliorates experimental dermal and pulmonary fibrosis

Objectives

We aimed to assess the expression of the CCL24 chemokine in systemic sclerosis (SSc) and to evaluate the possible pathogenic implications of the CCL24/CCR3 axis using both in vitro and in vivo models. We further investigated the efficacy of an anti-CCL24 monoclonal antibody (mAb), CM-101, in inhibiting cell activation as well as dermal and pulmonary inflammation and fibrosis in experimental animal models.

Methods

We used ELISA and fluorescence immunohistochemistry to determine CCL24 levels in serum and CCL24/CCR3 expression in skin biopsies of SSc patients. Skin fibroblasts and endothelial cells treated with CCL24 or SSc serum with or without CM-101 were used to follow cell activation and differentiation. Prevention and treatment in vivo bleomycin (BLM)-induced models were used to evaluate experimental dermal and pulmonary fibrosis progression following treatment with the CM-101 mAb.

Results

CCL24 circulating levels were significantly elevated in SSc patients. CCL24/CCR3 expression was strongly increased in SSc skin. Blockade of CCL24 with CM-101 significantly reduced the activation of dermal fibroblasts and their transition to myofibroblasts induced by SSc serum. CM-101 was also able to significantly inhibit endothelial cell activation induced by CCL24. In BLM-induced experimental animal models, CM-101 profoundly inhibited both dermal and pulmonary fibrosis and inflammation.

Conclusions

CCL24 plays an important role in pathological processes of skin and lung inflammation and fibrosis. Inhibition of CCL24 by CM-101 mAb can be potentially beneficial for therapeutic use in SSc patients.

Histone modifications underlie monocyte dysregulation in patients with systemic sclerosis, underlining the treatment potential of epigenetic targeting

BACKGROUND AND OBJECTIVE

Systemic sclerosis (SSc) is a severe autoimmune disease, in which the pathogenesis is dependent on both genetic and epigenetic factors. Altered gene expression in SSc monocytes, particularly of interferon (IFN)-responsive genes, suggests their involvement in SSc development. We investigated the correlation between epigenetic histone marks and gene expression in SSc monocytes.

METHODS

Chromatin immunoprecipitation followed by sequencing (ChIPseq) for histone marks H3K4me3 and H3K27ac was performed on monocytes of nine healthy controls and 14 patients with SSc. RNA sequencing was performed in parallel to identify aberrantly expressed genes and their correlation with the levels of H3K4me3 and H3K27ac located nearby their transcription start sites. ChIP-qPCR assays were used to verify the role of bromodomain proteins, H3K27ac and STATs on IFN-responsive gene expression.

RESULTS

1046 and 534 genomic loci showed aberrant H3K4me3 and H3K27ac marks, respectively, in SSc monocytes. The expression of 381 genes was directly and significantly proportional to the levels of such chromatin marks present near their transcription start site. Genes correlated to altered histone marks were enriched for immune, IFN and antiviral pathways and presented with recurrent binding sites for IRF and STAT transcription factors at their promoters. IFNα induced the binding of STAT1 and STAT2 at the promoter of two of these genes, while blocking acetylation readers using the bromodomain BET family inhibitor JQ1 suppressed their expression.

CONCLUSION

SSc monocytes have altered chromatin marks correlating with their IFN signature. Enzymes modulating these reversible marks may provide interesting therapeutic targets to restore monocyte homeostasis to treat or even prevent SSc.

Perivascular Adventitial Fibroblast Specialization Accompanies T Cell Retention in the Inflamed Human Dermis

Perivascular accumulation of lymphocytes can be a prominent histopathologic feature of various human inflammatory skin diseases. Select examples include systemic sclerosis, spongiotic dermatitis, and cutaneous lupus. Although a large body of work has described various aspects of the endothelial and vascular smooth muscle layers in these diseases, the outer adventitial compartment is poorly explored. The goal of the current study was to characterize perivascular adventitial fibroblast states in inflammatory human skin diseases and relate these states to perivascular lymphocyte accumulation. In normal skin, adventitial fibroblasts are distinguished by CD90 expression, and dense perivascular lymphocytic infiltrates are uncommon. In systemic sclerosis, this compartment expands, but lymphocyte infiltrates remain sparse. In contrast, perivascular adventitial fibroblast expression of VCAM1 is upregulated in spongiotic dermatitis and lupus and is associated with a dense perivascular T cell infiltrate. VCAM1 expression marks transitioned fibroblasts that show some resemblance to the reticular stromal cells in secondary lymphoid organs. Expanded adventitial compartments with perivascular infiltrates similar to the human settings were not seen in the inflamed murine dermis. This species difference may hinder the dissection of aspects of perivascular adventitial pathology. The altered perivascular adventitial compartment and its associated reticular network form a niche for lymphocytes and appear to be fundamental in the development of an inflammatory pattern.

Effects of soy phytoestrogens on pituitary-ovarian function in middle-aged female rats

The aim of this study was to assess the effects of genistein (G) and daidzein (D) on the histological, hormonal, and functional parameters of the pituitary-ovarian axis in middle-aged female rats, and to compare these effects with the effects of estradiol (E), commonly used in the prevention and treatment of menopausal symptoms. Middle-aged (12 month old) Wistar female rats subcutaneously received 35 mg/kg of G, or 35 mg/kg of D, or 0.625 mg/kg of E every day for 4 weeks. Each of the treated groups had a corresponding control group. An intact control group was also established. G and D did not change the intracellular protein content within gonadotropic and lactotropic cells, but vacuolization was observed in all the cell types. In contrast, E caused an inhibition of gonadotropic and stimulation of lactotropic cells. Also, ovaries of middle-aged female rats exposed to G or D have more healthy primordial and primary follicles and less atretic follicles. E treatment in the ovaries had a mostly negative effect, which is reflected by the increased number of atretic follicles in all tested classes. G and D provoked decrease in CuZnSOD and CAT activity, while E treatment increased MnSOD and decreased CuZnSOD and GSHPx activity. All the treatments increased serum estradiol and decreased testosterone levels, while D and E increased the serum progesterone level. In conclusion, soy phytoestrogens exhibited beneficial effects on pituitary-ovarian function in middle-aged female rats, as compared to estradiol.

Testosterone and estradiol treatments differently affect pituitary-thyroid axis and liver deiodinase 1 activity in orchidectomized middle-aged rats

We previously reported that orchidectomy (Orx) of middle-aged rats (15-16-month-old; MA) slightly affected pituitary-thyroid axis, but decreased liver deiodinase (Dio) type 1 and pituitary Dio2 enzyme activities. At present, we examined the effects of subsequent testosterone-propionate treatment (5mg/kg; Orx+T), and compared the effects of testosterone with the effects of estradiol-dipropionate (0.06mg/kg; Orx+E) treatment. Hormones were subcutaneously administered, daily, for three weeks, while Orx and sham-operated (SO) controls received only the vehicle. The applied dose of T did not alter serum TSH, T4 and T3 concentrations in Orx- MA, though it increased TSH when administrated to Orx young adults (2.5-month-old; Orx-YA). However, pituitaries of Orx-MA+T rats had higher relative intensity of immunofluorescence (RIF) for TSHβ; in their thyroids we found increased volume and height of follicular epithelium, decreased volume of the colloid and higher RIF for T4-bound to thyroglobulin (Tg-T4). Liver Dio1 activity was increased. E-treatment did not affect serum hormone levels, pituitary RIF for TSHβ, or liver Dio1 activity in Orx-MA rats. Thyroids had decreased relative volume and height of follicular epithelium, increased relative volume of the colloid, decreased volume of sodium-iodide symporter-immunopositive epithelium and lower RIF for Tg-T4. Detected changes were statistically significant. In conclusion, androgenization enhanced pituitary TSHβ RIF, thyroid activation and liver Dio1 enzyme activity in Orx-MA, without elevating serum TSH as in Orx-YA rats. Estrogenization induced pituitary enlargement with no effect on pituitary TSHβ RIF, serum TSH or liver Dio1 activity. E also induced alterations in thyroid histology that indicate mild suppression of its functioning, and contributed to thyroid blood vessel enlargement in Orx-MA rats.

Are there any causes for increased thyroid volume in women with prolactinoma?

PURPOSE

The aim of this study was to evaluate thyroid volume in women with prolactinoma and investigate the relationship between anabolic hormones [insulin, insulin like growth factor (IGF-1), estrogen] and thyroid volume in the patients.

MATERIAL-METHOD

Sixty-three euthyroid women with prolactinoma and 60 healthy euthyroid women were included. Serum prolactin (PRL), thyroid-stimulating hormone (TSH), thyroxine (free T4), free tri-iodothyronine (free T3), insulin resistance (IR) which was estimated by the homeostasis model assessment, thyroidal microsome (anti-TPO), antithyroglobulin antibodies (TgAb), estradiol (E2), and insulin like growth factor (IGF-1) were evaluated, and thyroid volume was calculated by B-mode doppler USG.

RESULTS

The mean thyroid volume was significantly higher in women with prolactinoma (82.5±15.1mL) than in healthy women (76±15.1mL)(P=0.014), but no correlation was found between thyroid volume and serum PRL levels (P=0.967). There were also no differences between thyroid volume, anabolic hormones (E2, IGF-1), and insulin resistance in women with prolactinoma (P=0.776, P=0.786, P=0.647, respectively).

CONCLUSIONS

Our study did not show an association between anabolic hormones and increased thyroid volume in women with prolactinoma.

Sexual dimorphism and thyroid dysfunction: a matter of oxidative stress?

Thyroid diseases, such as autoimmune disease and benign and malignant nodules, are more prevalent in women than in men, but the mechanisms involved in this sex difference is still poorly defined. H₂O₂ is produced at high levels in the thyroid gland and regulates parameters such as cell proliferation, migration, survival, and death; an imbalance in the cellular oxidant-antioxidant system in the thyroid may contribute to the greater incidence of thyroid disease among women. Recently, we demonstrated the existence of a sexual dimorphism in the thyrocyte redox balance, characterized by higher H₂O₂ production, due to higher NOX4 and Poldip2 expression, and weakened enzymatic antioxidant defense in the thyroid of adult female rats compared with male rats. In addition, 17β-estradiol administration increased NOX4 mRNA expression and H₂O₂ production in thyroid PCCL3 cells. In this review, we discuss the possible involvement of oxidative stress in estrogen-related thyroid pathophysiology. Our current hypothesis suggests that a redox imbalance elicited by estrogen could be involved in the sex differences found in the prevalence of thyroid dysfunctions.

Soy isoflavones interfere with thyroid hormone homeostasis in orchidectomized middle-aged rats

We previously reported that genistein (G) and daidzein (D) administered subcutaneously (10mg/kg) induce changes in the angio-follicular units of the thyroid gland, reduce concentration of total thyroid hormones (TH) and increase thyrotropin (TSH) in serum of orchidectomized middle-aged (16-month-old) rats. To further investigate these effects, we now examined expression levels of the thyroglobulin (Tg), thyroperoxidase (Tpo), vascular endothelial growth factor A (Vegfa) and deiodinase type 1 (Dio 1) genes in the thyroid; in the pituitary, genes involved in TH feedback control (Tsh β, Dio 1, Dio 2, Trh receptor); and in the liver and kidney, expression of T3-activated genes Dio 1 and Spot 14, as well as transthyretin (Ttr), by quantitative real-time PCR. We also analyzed TPO-immunopositivity and immunofluorescence of T4 bound to Tg, determined thyroid T4 levels and measured deiodinase enzyme activities in examined organs. Decreased expression of Tg and Tpo genes (p<0.05) correlated with immunohistochemical staining results, and together with decreased serum total T4 levels, indicates decreased Tg and TH synthesis following treatments with both isoflavones. However, expression of Spot 14 (p<0.05) gene in liver and kidney was up-regulated, and liver Dio 1 expression and activity (p<0.05) increased. At the level of pituitary, no significant change in gene expression levels, or Dio 1 and 2 enzyme activities was observed. In conclusion, both G and D impaired Tg and TH synthesis, but at the same time increased tissue availability of TH in peripheral tissues of Orx middle-aged rats.

The relationship between LH and thyroid volume in patients with PCOS

Background

Thyroid volume (TV) has been found to be associated with age, anthropometry, smoking, iodine status and hyperinsulinemia. Hyperinsulinemia is frequent finding in patients with PCOS and has associations with TV. However, the TV has been evaluated only a few studies in patients with PCOS. Therefore, the aim of this study was to evaluate the biochemical and hormonal variables in patients with PCOS comparing with the controls and their relationships between TV.

Methods

This was a case–control study conducted in a training and research hospital. The study population consisted of 47 reproductive-age PCOS women and 30 control subjects. We evaluated anthropometric, biochemical and hormonal parameters as well as thyroid volume in PCOS patients and controls. Insulin resistance was calculated using the homeostasis model assessment insulin resistance index (HOMA-IR).

Results

Mean age, BMI, thyroid stimulant hormone (TSH) levels and TV were similar between groups (p<0.05). The HOMA-IR and free T4 levels were higher in patients with PCOS. However, hyperinsulinemia and insulin resistance were not found to be associated with TV. Thyroid volume was positively correlated with the LH and anti TPO levels. The participants were divided into 2 groups according to HOMA-IR levels. The mean TV measurement was higher in group with higher HOMA-IR levels, but the difference was not significant in young age PCOS patients.

Conclusion

In early age PCOS patients it was observed that insulin resistance had no effect on TV. In this case, anti TPO and LH have dominant effect on TV. Chronic stimulation with LH and insulin may lead to increase in TV in later stages of the PCOS diseases.

Medical hypothesis: can gonadotropins influence thyroid volume in women with PCOS?

It has been reported that luteinizing hormone (LH) had thyropropic effect on rat and human thyroid membrane. It has been known that patients with PCOS have elevated LH levels in comparison to healthy controls.The goiter prevalence is more common in women than in men regardless of population. The higher incidence of thyroid diseases in women has been previously attributed to higher estradiol levels. Estradiol has been shown to enhance proliferative and mitogenic activities of thyroid cells. However, in recent years chronic estradiol treatment has been shown to reduce volume densities of thyroid follicles, follicular epithelium and thyroid gland volume. It is thought to be due to LH suppression.Therefore we suggested that increased LH levels might provide a stimulus for growth on thyroid and alter thyroid function. Therefore patients with PCOS who had elevated LH levels should be treated by combined estradiol pills such as estrogen-progestin contraceptives for suppression of LH secretion. Further studies are needed to evaluate the association between LH, LH suppression and thyroid volume in patients with PCOS.

Sonographic evaluation of thyroid morphology during the normal estrous cycle in the Indo-Pacific bottlenose dolphin (Tursiops aduncus)

Physiologic changes occurring in the thyroid in response to the estrous cycle have been noted in companion animals. However, in bottlenose dolphins, the influence of different reproductive states on thyroid morphology remains unclear. Sonography was used to evaluate the variations of thyroid morphology for nine consecutive estrous cycles of four sexually mature, female Indo-Pacific bottlenose dolphins (Tursiops aduncus). The estrous cycle was divided into two phases for evaluation: the follicular and luteal phases. To compare changes associated with sex, thyroid volumes were measured in the different phases during the estrous cycle of female dolphins and were compared to the ultrasound examinations of the four male dolphins measured over a 2-mo period. In males, there was no significant difference in thyroid volume during the study period (P > 0.05). The thyroid volume measured in combining all estrous cycle phases of the female dolphins was significantly larger than that measured in the male dolphins (P < 0.05). A difference in thyroid volume during the estrous cycle was observed, with the thyroid volume during the follicular phase significantly smaller (P < 0.05) than that of the luteal phase, and is possibly related to the influence of female sex steroids. Thyroid volume variability during estrus should, therefore, be taken into account when examining the thyroid gland of female dolphins.

The thyroid lobes: the different twins

Although differences in size of the right and left thyroid lobes are well defined, differences in morphology, follicles structure, cAMP production, thyrotropin receptor, and protein involved in cell signalling have not previously been reported. This study provides morpho-functional data of right and left thyroid lobes by biochemical, immunohistochemistry, immunoblotting and immunofluorescence analysis. We demonstrate that, in comparison with the left lobe, the right lobe has a higher activation index, is more sensitive to thyrotropin treatment, is rich in thyrotropin receptor and caveolin 1 involved in thyroid hormone synthesis as well as in epithelial thyroid cell homeostasis, is characterised by a high content of molecules involved in cell signalling such as stat3, raf1, sphingomyelinase and sphingomyelin-synthase whose activity ratio is necessary for epithelial cell activity and finally has more areas calcitonin-dependent. The relation between structure/function of right lobe and its susceptibility to the higher risk of pathological modifications with respect the left lobe is discussed.

Infliximab may be effective in the treatment of steroid-resistant eosinophilic fasciitis: report of three cases

OBJECTIVE

EF is a rare fibrosing disorder that may involve skin and internal organs. Current therapies include moderate- to high-dose glucocorticoids with or without use of immunosuppressives.

METHODS

We report three cases of steroid-resistant EF in clinical practice who were treated with 3 mg/kg every 8 weeks infliximab therapy.

RESULTS

All patients noticed an improvement in their symptoms, joint contractures and skin thickening within 8 weeks of starting infliximab therapy, ultimately leading to a drug-free remission (range 1-3 years).

CONCLUSION

Based on this and other reported cases, infliximab may be beneficial in patients with steroid-resistant EF.

Effects of chronic estradiol treatment on the thyroid gland structure and function of ovariectomized rats

BACKGROUND

Estrogen therapy is widely used nowadays in women to treat many postmenopausal symptoms but it may have some undesirable effects due to multiple organs affection. So, the aim of this study was to determine the effects of chronic estradiol treatment on the structure and function of the thyroid gland in ovarictomized rats as a model simulating menopause.

FINDINGS

Thirty adult female Wistar rats divided into three groups were used in this study; the first group was sham-operated, while the second and third groups were ovariectomized. The first and second groups were injected with olive oil while the third group was injected with estradiol dipropionate daily for three months, after that; hormonal assay for T3, T4, TSH and specimens of the thyroid were taken and processed to be examined by light and electron microscopy. The results of this study revealed that serum levels of T3 and T4 decreased in ovariectomized animals and significantly increased after estradiol treatment, while TSH increased in ovariectomized animals and decreased with estradiol treatment. Histological and morphometric study in ovariectomized group revealed marked accumulation of colloid in follicular lumens with decreased epithelial height in addition to increased connective tissue amount. After estradiol treatment the follicles became smaller in size, having small amount of colloid with increased epithelial height in addition to decreased connective tissue content. Ultrastructural study supported these results in addition to the presence of large amount of intracytoplasmic colloid vesicles after estradiol treatment.

CONCLUSION

Low estrogen level may lead to mild thyroidal hypofunction while estradiol treatment may lead to hyperactivity so it should be used very cautiously in the treatment of postmenopausal symptoms to avoid its undesirable stimulatory effect on the thyroid.

Estrogen effects on thyroid iodide uptake and thyroperoxidase activity in normal and ovariectomized rats

Sex steroids interfere with the pituitary-thyroid axis function, although the reports have been controversial and no conclusive data is available. Some previous reports indicate that estradiol might also regulate thyroid function through a direct action on the thyrocytes. In this report, we examined the effects of low and high doses of estradiol administered to control and ovariectomized adult female rats and to pre-pubertal females. We demonstrate that estradiol administration to both intact adult and pre-pubertal females causes a significant increase in the relative thyroid weight. Serum T3 is significantly decreased in ovariectomized rats, and is normalized by estrogen replacement. Neither doses of estrogen produced a significant change in serum TSH and total T4 in ovariectomized, adult intact and pre-pubertal rats. The highest, supraphysiological, estradiol dose produced a significant increase in thyroid iodide uptake in ovariectomized and in pre-pubertal rats, but not in control adult females. Thyroperoxidase activity was significantly higher in intact adult rats treated with both estradiol doses and in ovariectomized rats treated with the highest estradiol dose. Since serum TSH levels were not significantly changed, we suggest a direct action of estradiol on the thyroid gland, which depends on the age and on the previous gonad status of the animal.

Effects of ovariectomy and chronic estradiol administration on pituitary–thyroid axis in adult rats

The effects of ovariectomy (Ovx) and of ovariectomy followed by chronic estradiol dipropionate administration (Ovx EDP) on the structure and function of the pituitary-thyroid axis were examined in the rat. Pituitary TSH cells and thyroid tissue were histologically, immunohistochemically and stereologically investigated. Serum TSH and T(4) levels were determined by RIA. Ovx did not affect pituitary weight, but subsequent treatment with EDP led to its more than two-fold increase (p<0.05). After ovariectomy, the cellular volume of pituitary TSH-immunoreactive cells increased by 28%, p<0.05 compared to sham-operated animals (SO). Treatment of Ovx rats with EDP partially reversed this change. However, the relative volume density of thyrotrophs decreased in comparison to the Ovx and SO groups (by 18% and 23%, p<0.05, respectively). No statistically significant differences in serum TSH levels were observed between the experimental groups. In thyroid tissue both peripheral and central follicles responded to Ovx and EDP treatments. Compared to SO rats, the relative volume densities of the follicles and colloid were increased (by 14% and 30%, p<0.05, respectively) in Ovx rats. Chronic EDP treatment of Ovx rats reversed these changes to the pre-ovariectomy state. Hyperplasia of thyroid follicular cells and a significant reduction (by 21%, p<0.05) of the serum level of T(4) were detected. In conclusion, estradiol deficiency and chronic treatment affected pituitary TSH cells and thyroid tissue. The sum effect of Ovx on the pituitary-thyroid axis was slightly stimulatory. Subsequent EDP treatment decreased thyroid functioning but at the same time preserved serum TSH at the control level.

Immunoreactive TSH cells in juvenile and peripubertal rats after estradiol and human chorionic gonadotropin treatment

Different hormones and growth factors control the homeostasis of the anterior pituitary gland. We examined the morphological features of pituitary thyroid stimulating hormone (TSH)-producing cells in juvenile and peripubertal female rats after treatments with estradiol-dipropionate (EDP), human chorionic gonadotropin (hCG) and a combination of both hormones (EDP+hCG). TSH-producing cells were labelled using a peroxidase-antiperoxidase immunohistochemical procedure for binding of a rabbit anti-rat beta-thyrotropic polyclonal antisera. Morphometric differences in the cytoplasmic and nuclear volume densities in thyrotropes after the treatments were determined using a stereological method. The relative weights of the pituitary glands were significantly higher in the EDP- and EDP+hCG-treated juvenile and peripubertal rats than in untreated age-matched controls. Treatment with EDP promoted a decrease, and treatment with hCG an increase, of the cellular and nuclear volumes in TSH cells in both juvenile and peripubertal females in comparison with the respective controls. Treatment with a combination of EDP+hCG did not induce any significant changes. The cytoplasmic and nuclear volume densities in TSH cells in the EDP+hCG-treated group were significantly higher than in the EDP-treated, and significantly lower than in hCG-treated rats at both growth stages. These findings suggest that estradiol and hCG exerted opposite effects on pituitary TSH-immunoreactive cells. The observed effects on thyrotrope morphology were apparently independent of the stage of development.

Oligoclonal T cell expansion in the skin of patients with systemic sclerosis

Fibrosis, microvascular fibroproliferative alterations, and autoantibody production are the main features of systemic sclerosis (SSc), and all of them can be explained by cytokine production by activated T cells. However, little is known about the role of T cells in the pathogenesis of SSc, and there is no information on the Ag(s) that elicits such activation. To determine whether T cells infiltrating the skin biopsies of patients with SSc are oligoclonal, beta-chain TCR transcripts from T cells infiltrating the skin of five patients with SSc of recent onset were amplified by either Vbeta-specific PCR or nonpalindromic adaptor PCR. The resulting PCR products were subsequently cloned and sequenced. High proportions of identical beta-chain TCR transcripts ranging from 43 to 90% of those sequenced were found in five patients, strongly suggesting the presence of oligoclonal T cells in these infiltrates. A dominant T cell clone was found to be clonally expanded in skin biopsies obtained from a single patient with SSc at three different times (0, 8, and 13 mo earlier) and from three different skin regions. beta-chain TCR transcripts from PBMC from normal donors (methodological control) were unique when compared with each other, typical for polyclonal populations of T cells. The finding of oligoclonal T cells infiltrating the skin of patients with SSc suggests that these T cells have undergone proliferation in situ in the skin and clonal expansion in response to as yet unidentified Ag(s). These results suggest that T cells are involved in the pathogenesis of the disease.

Murine sclerodermatous graft-versus-host disease, a model for human scleroderma: cutaneous cytokines, chemokines, and immune cell activation

Murine sclerodermatous graft-vs-host disease (Scl GVHD) models human scleroderma, with prominent skin thickening, lung fibrosis, and up-regulation of cutaneous collagen mRNA. Fibrosis in Scl GVHD may be driven by infiltrating TGF-beta1-producing mononuclear cells. Here we characterize the origin and types of those cutaneous effector cells, the cytokine and chemokine environments, and the effects of anti-TGF-beta Ab on skin fibrosis, immune cell activation markers, and collagen and cytokine synthesis. Donor cells infiltrating skin in Scl GVHD increase significantly at early time points post-transplantation and are detectable by PCR analysis of Y-chromosome sequences when female mice are transplanted with male cells. Cutaneous monocyte/macrophages and T cells are the most numerous cells in Scl GVHD compared with syngeneic controls. These immune cells up-regulate activation markers (MHC class II I-A(d) molecules and class A scavenger receptors), suggesting Ag presentation by cutaneous macrophages in early fibrosing disease. Early elevated cutaneous mRNA expression of TGF-beta1, but not TGF-beta2 or TGF-beta3, and elevated C-C chemokines macrophage chemoattractant protein-1, macrophage inflammatory protein-1alpha, and RANTES precede subsequent skin and lung fibrosis. Therefore, TGF-beta1-producing donor mononuclear cells may be critical effector cells, and C-C chemokines may play important roles in the initiation of Scl GVHD. Abs to TGF-beta prevent Scl GVHD by effectively blocking the influx of monocyte/macrophages and T cells into skin and by abrogating up-regulation of TGF-beta1, thereby preventing new collagen synthesis. The Scl GVHD model is valuable for testing new interventions in early fibrosing diseases, and chemokines may be new potential targets in scleroderma.