Triiodothyronine regulates angiogenic growth factor and cytokine secretion by isolated human decidual cells in a cell-type specific and gestational age-dependent manner.

STUDY QUESTION: Does triiodothyronine (T3) regulate the secretion of angiogenic growth factors and cytokines by human decidual cells isolated from early pregnancy? SUMMARY ANSWER: T3 modulates the secretion of specific angiogenic growth factors and cytokines, with different regulatory patterns observed amongst various isolated subpopulations of human decidual cells and with a distinct change between the first and second trimesters of pregnancy. WHAT IS KNOWN ALREADY: Maternal thyroid dysfunction during early pregnancy is associated with complications of malplacentation including miscarriage and pre-eclampsia. T3 regulates the proliferation and apoptosis of fetal-derived trophoblasts, as well as promotes the invasive capability of extravillous trophoblasts (EVT). We hypothesize that T3 may also have a direct impact on human maternal-derived decidual cells, which are known to exert paracrine regulation upon trophoblast behaviour and vascular development at the uteroplacental interface. STUDY DESIGN, SIZE, DURATION: This laboratory-based study used human decidua from first (8-11 weeks; n = 18) and second (12-16 weeks; n = 12) trimester surgical terminations of apparently uncomplicated pregnancies. PARTICIPANTS/MATERIALS, SETTING, METHODS: Primary cultures of total decidual cells, and immunomagnetic bead-isolated populations of stromal-enriched (CD10+) and stromal-depleted (CD10-) cells, uterine natural killer cells (uNK cells; CD56+) and macrophages (CD14+) were assessed for thyroid hormone receptors and transporters by immunocytochemistry. Each cell population was treated with T3 (0, 1, 10, 100 nM) and assessments were made of cell viability (MTT assay) and angiogenic growth factor and cytokine secretion (immunomediated assay). The effect of decidual cell-conditioned media on EVT invasion through Matrigel(®) was evaluated. MAIN RESULTS AND THE ROLE OF CHANCE: Immunocytochemistry showed the expression of thyroid hormone transporters (MCT8, MCT10) and receptors (TRα1, TRß1) required for thyroid hormone-responsiveness in uNK cells and macrophages from the first trimester. The viability of total decidual cells and the different cell isolates were unaffected by T3 so changes in cell numbers could not account for any observed effects. In the first trimester, T3 decreased VEGF-A secretion by total decidual cells (P < 0.05) and increased angiopoietin-2 secretion by stromal-depleted cells (P < 0.05) but in the second trimester total decidual cells showed only increased angiogenin secretion (P < 0.05). In the first trimester, T3 reduced IL-10 secretion by total decidual cells (P < 0.05), and reduced granulocyte macrophage colony stimulating factor (P < 0.01), IL-8 (P < 0.05), IL-10 (P < 0.01), IL-1ß (P < 0.05) and monocyte chemotactic protein -1 (P < 0.001) secretion by macrophages, but increased tumour necrosis factor-α secretion by stromal-depleted cells (P < 0.05) and increased IL-6 by uNK cells (P < 0.05). In contrast, in the second trimester T3 increased IL-10 secretion by total decidual cells (P < 0.01) but did not affect cytokine secretion by uNK cells and macrophages. Conditioned media from first trimester T3-treated total decidual cells and macrophages did not alter EVT invasion compared with untreated controls. Thus, treatment of decidual cells with T3 resulted in changes in both angiogenic growth factor and cytokine secretion in a cell type-specific and gestational age-dependent manner, with first trimester decidual macrophages being the most responsive to T3 treatment, but these changes in decidual cell secretome did not affect EVT invasion in vitro. LIMITATIONS, REASONS FOR CAUTION: Our results are based on in vitro findings and we cannot be certain if a similar response occurs in human pregnancy in vivo. WIDER IMPLICATIONS OF THE FINDINGS: Optimal maternal thyroid hormone concentrations could play a critical role in maintaining a balanced inflammatory response in early pregnancy to prevent fetal immune rejection and promote normal placental development through the regulation of the secretion of critical cytokines and angiogenic growth factors by human decidual cells. Our data suggest that there is an ontogenically determined regulatory 'switch' in T3 responsiveness between the first and second trimesters, and support the notion that the timely and early correction of maternal thyroid dysfunction is critical in influencing pregnancy outcomes. STUDY FUNDING/COMPETING INTEREST(S): This study is funded by Wellbeing of Women (RG/1082/09 to S.Y.C., M.D.K., J.A.F., L.S.L., G.E.L.) and Action Medical Research - Henry Smith Charity (SP4335 to M.D.K., S.Y.C., L.S.L., J.A.F.). The authors have no conflicts of interest to disclose.

The expression of thyroid hormone transporters in the human fetal cerebral cortex during early development and in N-Tera-2 neurodifferentiation.

Associations of neurological impairment with mutations in the thyroid hormone (TH) transporter, MCT8, and with maternal hypothyroxinaemia, suggest that THs are crucial for human fetal brain development. It has been postulated that TH transporters regulate the cellular supply of THs within the fetal brain during development. This study describes the expression of TH transporters in the human fetal cerebral cortex (7­20 weeks gestation) and during retinoic acid induced neurodifferentiation of the human N-Tera-2 (NT2) cell line, in triiodothyronine (T3) replete and T3-depleted media. Compared with adult cortex, mRNAs encoding OATP1A2, OATP1C1, OATP3A1 variant 2, OATP4A1, LAT2 and CD98 were reduced in fetal cortex at different gestational ages, whilst mRNAs encoding MCT8, MCT10, OATP3A1 variant 1 and LAT1 were similar. From the early first trimester, immunohistochemistry localised MCT8 and MCT10 to the microvasculature and to undifferentiated CNS cells. With neurodifferentiation, NT2 cells demonstrated declining T3 uptake, accompanied by reduced expressions of MCT8, LAT1, CD98 and OATP4A1. T3 depletion significantly reduced MCT10 and LAT2 mRNA expression at specific time points during neurodifferentiation but there were no effects upon T3 uptake, neurodifferentiation marker expression or neurite lengths and branching. MCT8 repression also did not affect NT2 neurodifferentiation. In conclusion, many TH transporters are expressed in the human fetal cerebral cortex from the first trimester, which could regulate cellular TH supply during early development. However, human NT2 neurodifferentiation is not dependent upon T3 or MCT8 and there were no compensatory changes to promote T3 uptake in a T3-depleted environment.

Expression and function of thyroid hormone transporters in the microvillous plasma membrane of human term placental syncytiotrophoblast.

The transplacental passage of thyroid hormones (THs) from mother to fetus in humans has been deduced from observational clinical studies and is important for normal fetoplacental development. To investigate the transporters that regulate TH uptake by syncytiotrophoblast (the primary barrier to maternal-fetal exchange, which lies in direct contact with maternal blood), we isolated the microvillous plasma membrane (MVM) of human term syncytiotrophoblasts. We have demonstrated that MVM vesicles express plasma membrane TH transporter proteins, including system-L (L-type amino acid transporter 1 and CD98), monocarboxylate transporters (MCTs) 8 and 10, organic anion-transporting polypeptides 1A2 and 4A1. We provide the first definitive evidence that the human syncytiotrophoblast MVM is capable of rapid, saturable T(4) and T(3) uptake at similar rates and in a Na(+)-independent manner. These two major forms of THs could not significantly inhibit each others' uptake, suggesting that each is mediated by largely different transporters. No single transporter was noted to play a dominant role in either T(4) or T(3) uptake. Using combinations of transporter inhibitors that had an additive effect on TH uptake, we provide evidence that 67% of saturable T(4) uptake is facilitated by system-L and MCT10 with a minor role played by organic anion-transporting polypeptides, whereas 87% of saturable T(3) uptake is mediated by MCT8 and MCT10. Our data demonstrate that syncytiotrophoblast may control the quantity and forms of THs taken up by the human placenta. Thus, syncytiotrophoblast could be critical in regulating transplacental TH supply from the mother to the fetus.

Differential triiodothyronine responsiveness and transport by human cytotrophoblasts from normal and growth-restricted pregnancies.

CONTEXT: Abnormal placentation in human pregnancy is associated with intrauterine fetal growth restriction (IUGR). Our group has previously reported the association between severe IUGR, lower fetal circulating concentrations of thyroid hormones (THs), and altered expression of TH receptors and TH transporters within human placental villi. We postulate that altered TH bioavailability to trophoblasts may contribute to the pathogenesis of IUGR. DESIGN AND OBJECTIVE: Cytotrophoblasts were isolated from normal and IUGR human placentae to compare their responsiveness to T(3) and their capability for T(3) transport. RESULTS: Compared with normal cytotrophoblasts, the viability of IUGR cytotrophoblasts (assessed by methyltetrazoleum assay) was significantly reduced (P < 0.001), whereas apoptosis (assessed using caspase 3/7 activity and M30 immunoreactivity) was significantly increased after T(3) treatment for 48 h (P < 0.001 and P < 0.01, respectively). The secretion of human chorionic gonadotropin was significantly increased by IUGR cytotrophoblasts compared with normal cytotrophoblasts (P < 0.001), independently of T(3) treatment. Net transport of [(125)I]T(3) was 20% higher by IUGR cytotrophoblasts compared with normal cytotrophoblasts (P < 0.001), and this was accompanied by a 2-fold increase in the protein expression of the TH transporter, monocarboxylate transporter 8, as assessed by Western immunoblotting (P < 0.01). CONCLUSIONS: IUGR cytotrophoblasts demonstrate altered responsiveness to T(3) with significant effects on cell survival and apoptosis compared with normal cytotrophoblasts. Increased monocarboxylate transporter 8 expression and intracellular T(3) accumulation may contribute to the altered T(3) responsiveness of IUGR cytotrophoblasts.

Expression of thyroid hormone transporters in the human placenta and changes associated with intrauterine growth restriction.

Thyroid hormones (TH) are important for the development of the human fetus and placenta from very early gestation. The transplacental passage of TH from mother to fetus and the supply of TH into trophoblasts require the expression of placental TH plasma membrane transporters. We describe the ontogeny of the TH transporters MCT8, MCT10, LAT1, LAT2, OATP1A2 and OATP4A1 in a large series (n = 110) of normal human placentae across gestation and describe their expression changes with intrauterine fetal growth restriction (IUGR n = 22). Quantitative RT-PCR revealed that all the mRNAs encoding TH transporters are expressed in human placenta from 6 weeks gestation and throughout pregnancy. MCT8, MCT10, OATP1A2 and LAT1 mRNA expression increased with gestation. OATP4A1 and CD98 (LATs obligatory associated protein) mRNA expression reached a nadir in mid-gestation before increasing towards term. LAT2 mRNA expression did not alter throughout gestation. Immunohistochemistry localised MCT10 and OATP1A2 to villous cytotrophoblasts and syncytiotrophoblasts, and extravillous trophoblasts while OATP4A1 was preferentially expressed in the villous syncytiotrophoblasts. Whilst MCT8 protein expression was increased, MCT10 mRNA expression was decreased in placentae from IUGR pregnancies delivered in the early 3rd trimester compared to age matched appropriately grown for gestational age controls. No significant change was found in the mRNA expression of the other transporters with IUGR. In conclusion, several TH transporters are present in the human placenta from early 1st trimester with varying patterns of expression throughout gestation. Their coordinated effects may regulate both transplacental TH passage and TH supply to trophoblasts, which are critical for the normal development of the fetus and placenta. Increased MCT8 and decreased MCT10 expression within placentae of pregnancies complicated by IUGR may contribute to aberrant development of the fetoplacental unit.

Human leukocyte antigen class II alleles in Caucasian women with primary biliary cirrhosis.

In the current study, we investigated human leukocyte antigen (HLA) class II alleles in Caucasian women with primary biliary cirrhosis (PBC), a disease that preferentially affects women. Alleles of DRB1, DQA1, and DQB1 were determined by DNA-based HLA typing for women with PBC (n = 72) and healthy women (n = 381). All study subjects were Caucasian. HLA DRB1*08 was significantly increased in women with PBC compared to healthy women. The increase was primarily due to the DRB1*0801 allele, also the most common DRB1*08 allele among controls. DQB1*04 and DQA1*0401 were significantly increased. DRB1*1501, DQA1*0102, and DQB1*0602 were associated with decreased risk. Analyses conducted comparing parous women with PBC to parous healthy women (n = 68 and n = 282, respectively) yielded similar significant results. Although the DRB1*08-DQA1*0401-DQB1*04 haplotype was significantly associated with PBC, consistent with other studies, this haplotype nevertheless represented only 19% (14/72) of all PBC patients and can account for only a minority of the risk of PBC.

HLA allelic variants encoding DR11 in diffuse and limited systemic sclerosis in Caucasian women.

OBJECTIVE: We investigated HLA class II alleles in women with systemic sclerosis (SSc), a rare disease that preferentially affects women. METHODS: Specific alleles of DRB1, DQA1 and DQB1 were determined by DNA-based HLA typing for women with SSc (n = 102) and healthy women (n = 533). All study subjects were Caucasian. DRB1, DQA1 and DQB1 allele frequencies of women with SSc were compared with those of healthy women. RESULTS: Among women with SSc, 29.4% (30/102) and among healthy women 10.7% (57/533) had DRB1*11. Allele frequencies were compared for women with SSc and healthy women (each woman has two alleles). The allele frequency of DRB1*11 was 15.7% (32/204 alleles) in SSc women and 5.8% (62/1066 alleles) in healthy women (P = 0.000002). The increase of DRB1*11 was found both in diffuse (P = 0.0001) and limited SSc (P = 0.002) (allele frequencies 15.0 and 17.2%, respectively). Among women with diffuse SSc, there was a disproportionate increase of the DRB1*1104 allele (P = 0.0004) with no increase of DRB1*1101 (P = 1.00). In contrast, in limited SSc the strongest association was with DRB1*1101 (P = 0.008), with a less significant increase of DRB1*1104 (P = 0.04). CONCLUSIONS: An increase of DRB1*11 in SSc is consistent with other reports. Although present in both diffuse and limited SSc disease subsets, the increase was predominantly due to over-representation of DRB1*1104 in women with diffuse SSc. Women with limited SSc had a preponderance of DRB1*1101, the most common allele in healthy women. DRB1*1104 and DRB1*1101 differ by a single amino acid at position 86, where the former has valine and the latter glycine.