Decreased number of circulating endothelial progenitor cells in patients with Graves' hyperthyroidism

Association between maternal thyroid function and risk of gestational hypertension and pre-eclampsia: a systematic review and individual-participant data meta-analysis

BACKGROUND

Adequate maternal thyroid function is important for an uncomplicated pregnancy. Although multiple observational studies have evaluated the association between thyroid dysfunction and hypertensive disorders of pregnancy, the methods and definitions of abnormalities in thyroid function tests were heterogeneous, and the results were conflicting. We aimed to examine the association between abnormalities in thyroid function tests and risk of gestational hypertension and pre-eclampsia.

METHODS

In this systematic review and meta-analysis of individual-participant data, we searched MEDLINE (Ovid), Embase, Scopus, and the Cochrane Database of Systematic Reviews from date of inception to Dec 27, 2019, for prospective cohort studies with data on maternal concentrations of thyroid-stimulating hormone (TSH), free thyroxine (FT₄), thyroid peroxidase (TPO) antibodies, individually or in combination, as well as on gestational hypertension, pre-eclampsia, or both. We issued open invitations to study authors to participate in the Consortium on Thyroid and Pregnancy and to share the individual-participant data. We excluded participants who had pre-existing thyroid disease or multifetal pregnancy, or were taking medications that affect thyroid function. The primary outcomes were documented gestational hypertension and pre-eclampsia. Individual-participant data were analysed using logistic mixed-effects regression models adjusting for maternal age, BMI, smoking, parity, ethnicity, and gestational age at blood sampling. The study protocol was registered with PROSPERO, CRD42019128585.

FINDINGS

We identified 1539 published studies, of which 33 cohorts met the inclusion criteria and 19 cohorts were included after the authors agreed to participate. Our study population comprised 46 528 pregnant women, of whom 39 826 (85·6%) women had sufficient data (TSH and FT₄ concentrations and TPO antibody status) to be classified according to their thyroid function status. Of these women, 1275 (3·2%) had subclinical hypothyroidism, 933 (2·3%) had isolated hypothyroxinaemia, 619 (1·6%) had subclinical hyperthyroidism, and 337 (0·8%) had overt hyperthyroidism. Compared with euthyroidism, subclinical hypothyroidism was associated with a higher risk of pre-eclampsia (2·1% vs 3·6%; OR 1·53 [95% CI 1·09-2·15]). Subclinical hyperthyroidism, isolated hypothyroxinaemia, or TPO antibody positivity were not associated with gestational hypertension or pre-eclampsia. In continuous analyses, both a higher and a lower TSH concentration were associated with a higher risk of pre-eclampsia (p=0·0001). FT₄ concentrations were not associated with the outcomes measured.

INTERPRETATION

Compared with euthyroidism, subclinical hypothyroidism during pregnancy was associated with a higher risk of pre-eclampsia. There was a U-shaped association of TSH with pre-eclampsia. These results quantify the risks of gestational hypertension or pre-eclampsia in women with thyroid function test abnormalities, adding to the total body of evidence on the risk of adverse maternal and fetal outcomes of thyroid dysfunction during pregnancy. These findings have potential implications for defining the optimal treatment target in women treated with levothyroxine during pregnancy, which needs to be assessed in future interventional studies.

FUNDING

Arkansas Biosciences Institute and Netherlands Organization for Scientific Research.

Hyperthyroidism and vascular cell adhesion molecule-1 are associated with a low ankle-brachial index

We aimed to assess the ankle-brachial index (ABI) in patients with Graves' disease. In the cross-sectional assessments, 81 patients with drug-naïve Graves' disease and 235 with euthyroidism were enrolled. ABI and vascular cell adhesion molecule-1 (VCAM-1) levels were assessed. In the prospective follow-up, 32 patients with Graves' disease were assessed again after antithyroid drugs for at least 4 weeks, and 32 age- and sex-matched controls with euthyroidism were also followed up. Patients with Graves' disease had a higher VCAM-1 level (1309 ± 292 vs. 1009 ± 168 ng/mL, P < 0.001) and a lower ABI (0.98 ± 0.11 vs. 1.06 ± 0.10, P < 0.001) than those with euthyroidism. ABI was significantly lower in patients with hyperthyroidism and a high VCAM-1 level than in those with euthyroidism and a low VCAM-1 level (regression coefficient: - 0.050, 95% confidence interval [CI] between - 0.080 and - 0.019; P = 0.001). After treatment with antithyroid drugs, the change in free thyroxine (T4) level was inversely associated with the percentage change in ABI (regression coefficient: - 0.003, 95% CI between - 0.005 and - 0.001, P = 0.001). A synergistic effect of VCAM-1 and free T4 on ABI reduction was observed. After a longitudinal follow-up, an increase in ABI was significantly correlated with a decrease in the free T4 level.

Microvascular Density and Circulating Endothelial Progenitor Cells Before and After Treatment with Incretin Mimetics in Diabetic Patients

INTRODUCTION

Glucagon-like peptide 1-receptor agonists (incretin mimetics) and dipeptidyl peptidase-4 inhibitors (incretin enhancers) have been recently introduced in the treatment of diabetes mellitus. In particular, incretin mimetics seems to have ancillary antioxidant/antinflammatory properties that might be involved in endothelial protection.

AIM

To investigate the effect of incretin mimetic therapy (liraglutide, exenatide) given to 11 patients with type 2 diabetes mellitus, on circulating endothelial progenitor cells (EPCs) (bone marrow-derived cells possibly participating in neovascularization and endothelial protection and repair) and capillary density.

METHODS

Four diabetic patients were treated with exenatide (5 μg twice daily for 4 weeks and then 10 μg twice daily for 3 weeks) and 7 with liraglutide (0.6 mg per day for 1 week and then 1.2 mg per day for 3 weeks). Peripheral venous blood samples were obtained before treatment (basal) and after 4 week in patients treated with liraglutide, and after 4 and 7 weeks in patients treated with exenatide, since drug titration is usually longer. EPCs were evaluated by flow cytometry as CD34⁺/KDR⁺ cells. Capillary density was evaluated by videomicroscopy, before and after venous congestion, in the dorsum of the 4th finger.

RESULTS

Patients treated with liraglutide (6 males 1 female, age 54 ± 12 years) showed a decrease in body mass index and blood pressure during treatment, while patients treated with exenatide (3 males 1 female, age 57 ± 6 years) did not show any relevant change. EPCs were significantly increased after treatment with exenatide, but not after treatment with liraglutide. Capillary density was slightly increased only after 4 weeks of treatment with exenatide, however the increase was no longer present at the final evaluation.

CONCLUSIONS

Treatment with exenatide, but not with liraglutide, was able to increase the number of circulating EPCs, possibly through an antioxidative/antiinflammatory effect.

Effect of antihypertensive treatment with lercanidipine on endothelial progenitor cells and inflammation in patients with mild to moderate essential hypertension

BACKGROUND

It has been demonstrated that circulating endothelial progenitor cells (EPCs) number reflects the endogenous vascular repair ability, with the EPCs pool declining in presence of cardiovascular risk factors. Several drugs, including dihydropyridine calcium channel blockers, have been reported to elicit antioxidant and anti-inflammatory properties, as well as to improve vascular remodeling and dysfunction. However, no data are available about the effects of lercanidipine on EPCs. The aim of the present study was therefore to investigate the effects of short-term treatment with lercanidipine on circulating EPCs, as well as on indices of inflammation and oxidative stress.

PATIENTS AND METHODS

Twenty essential hypertensive patients were included in the study and treated for 4 weeks with lercanidipine 20 mg per day orally. Investigations were performed in basal condition, after appropriate wash out of previous treatments, and after 4 weeks of lercanidipine treatment. Inflammatory and oxidative stress markers were assessed by ELISA technique. Lin-/7AAD-/CD34+/CD133+/VEGFR-2 + and Lin-/7AAD-/CD34+/VEGFR-2 + cells were identified by flow cytometry and considered as EPCs. EPCs cells were expressed as number of cells per million Lin-mononuclear cells.

RESULTS

Circulating EPCs were significantly increased after lercanidipine treatment (CD34+/CD133+/VEGFR-2 + cells: 78.3 ± 64.5 vs 46.6 ± 32.8; CD34+/VEGFR-2+: 87996 ± 165116 vs 1026 ± 1559, respectively, p < 0.05). A modest reduction in circulating indices of inflammation was also observed.

CONCLUSIONS

In conclusion, lercanidipine is able to increase the number of circulating EPCs, possibly through a reduction of low-grade inflammation.

Are Endothelial Progenitor Cells the Real Solution for Cardiovascular Diseases? Focus on Controversies and Perspectives

Advanced knowledge in the field of stem cell biology and their ability to provide a cue for counteracting several diseases are leading numerous researchers to focus their attention on “regenerative medicine” as possible solutions for cardiovascular diseases (CVDs). However, the lack of consistent evidence in this arena has hampered the clinical application. The same condition affects the research on endothelial progenitor cells (EPCs), creating more confusion than comprehension. In this review, this aspect is discussed with particular emphasis. In particular, we describe biology and physiology of EPCs, outline their clinical relevance as both new predictive, diagnostic, and prognostic CVD biomarkers and therapeutic agents, discuss advantages, disadvantages, and conflicting data about their use as possible solutions for vascular impairment and clinical applications, and finally underline a very crucial aspect of EPCs “characterization and definition,” which seems to be the real cause of large heterogeneity existing in literature data on this topic.

Simultaneous measurement of serum chemokines in autoimmune thyroid diseases: possible role of IP-10 in the inflammatory response

Autoimmune thyroid diseases (AITDs), including Graves' diseases (GD) and Hashimoto's thyroiditis (HT), are the most common autoimmune diseases, and are mainly mediated by T cells that produce cytokines and chemokines in abnormal amounts. Few reports have described the circulating chemokines active in AITDs. Recently, we used a new multiplex immunobead assay to simultaneously measure cytokines and chemokines in small volume serum samples from patients with AITDs. We measured 23 selected serum chemokines in patients with GD (n=45) or HT (n=26), and healthy controls (n=9). GD patients were further classified as either untreated, intractable, or in remission, while HT patients were classified as either hypothyroid or euthyroid. Of the 23 serum chemokines assayed, only the serum level of IP-10 (CXCL10/interferon-γ-inducible protein 10) was elevated, depending on disease activity, in GD or HT compared with healthy controls. However, the serum level of IP-10 was also increased in both untreated GD patients and hypothyroid HT patients, suggesting that levels of this cytokine may not be affected by disease specificity. In conclusion, autoimmune inflammation in patients with AITD is closely related to the level of the serum chemokine, IP-10. Therefore, IP-10 might be a good biomarker for tissue inflammation in the thyroid, but not a useful biomarker for predicting disease specific activity, the progression of AITDs, or responsiveness to treatment because of its independence from thyroid function or disease specificity.

Maternal early-pregnancy thyroid function is associated with subsequent hypertensive disorders of pregnancy: the generation R study

CONTEXT

Hypertensive disorders during pregnancy are associated with a wide range of maternal and fetal complications, and only a few risk factors are known for the development of these disorders during pregnancy. Conflicting and limited data are available on the relationship between thyroid (dys)function and the risk of hypertensive disorders of pregnancy.

OBJECTIVE

The objective of the investigation was to study the associations between early-pregnancy thyroid dysfunction, thyroid function within the normal range, and the risk of hypertensive disorders.

DESIGN, SETTING, AND PARTICIPANTS

In early pregnancy, serum TSH, free T4 (FT4), and thyroperoxidase antibody (TPOAb) levels were determined in 5153 pregnant women. No interventions were done. The associations of thyroid function with the risk of hypertensive disorders were studied.

MAIN OUTCOME MEASURES

Mean blood pressures and hypertensive disorders, including pregnancy-induced hypertension (n = 209) and preeclampsia (n = 136), were measured.

RESULTS

Hyperthyroid mothers had a higher risk of hypertensive disorders [odds ratio (OR) 3.40 [95% confidence interval (CI) 1.46-7.91], P = .005], which was mainly due to an increased risk of pregnancy-induced hypertension [OR 4.18 (95% CI 1.57-11.1), P = .004]. Hypothyroidism and hypothyroxinemia were not associated with hypertensive disorders. Within the normal range, the high-normal FT4 levels were associated with an increased risk of hypertensive disorders [OR 1.62 (95% CI 1.06-2.47), P = .03], which was mainly due to an increased risk of preeclampsia [OR 2.06 (95% CI 1.04-4.08), P = .04]. The TPOAb status was not associated with hypertensive disorders.

CONCLUSIONS

We show that biochemical hyperthyroidism and also high-normal FT4 levels during early pregnancy are associated with an increased risk of hypertensive disorders. These data demonstrate that these associations are even seen for a mild variation in thyroid function within the normal range.

Endothelial dysfunction in Graves' disease

PURPOSE

Graves' disease (GD) is an organ-specific autoimmune thyroid disease, characterized by hyperthyroidism due to excessive production of thyroid hormone induced by thyrotropin receptor-specific stimulatory autoantibodies. In this study, we determined serum levels of the soluble forms of ICAM-1, VCAM-1, vWF, IL-6, IL-12, IL-18, fibrinogen and CRP in patients with subclinical (SH) and overt hyperthyroidism (OH) caused by GD to elucidate a possible role of those parameters as markers of endothelium dysfunction (ED).

MATERIAL/METHODS

The study included 96 patients: 52 with GD and 44 euthyroid controls, divided into 3 groups according to their thyroid function tests: SH, OH and controls (CG).

RESULTS

The values of IL-6, IL-12 and IL-18 were significantly higher in GD than in CG patients (p < 0.0001, p < 0.0001; p < 0.00001, respectively). Significant difference of sVCAM-1 values were found in the patients with GD compared to CG (p < 0.0001). Patients with GD had significantly higher levels of PAI-1 (p < 0.00001), vWF (p < 0.0001), fibrinogen (p < 0.0001) in comparison to CG. In patients with OH, we observed statistically higher values of fibrinogen compared to SH group (p < 0.05). There were no significant differences in serum concentration of other study parameters in patients with SH compared to the OH.

CONCLUSIONS

ED occurs during subclinical and overt hyperthyroidism causing decreased fibrinolytic activity, hypercoagulability and increased levels of IL-6, Il-12 and IL-18. These results support the notion that serum cytokines could be used as a marker of GD activity. Results of this study support the opinion that GD might require treatment as early as in the phase of SH.

Circulating endothelial progenitor cells, microvascular density and fibrosis in obesity before and after bariatric surgery

It is not known whether, in obesity, the capillary density or the number of circulating endothelial progenitor cells (EPCs) are reduced, or whether fibrosis of small vessels is also present. In addition, possible effects of weight reduction on these parameters have never been evaluated. Therefore, we investigated EPCs and capillary density in 25 patients with severe obesity, all submitted to bariatric surgery, and in 18 normotensive lean subjects and 12 hypertensive lean patients as controls. All patients underwent a biopsy of subcutaneous fat during bariatric surgery. In five patients, a second biopsy was obtained after consistent weight loss, about 1 year later, during a surgical intervention for abdominoplasty. EPCs and capillary density were reduced in obesity, and EPCs were significantly increased after weight reduction. Vascular collagen content was clearly increased in obese patients. No significant difference in vascular collagen was observed between normotensive obese patients and hypertensive obese patients. After pronounced weight reduction, collagen content was nearly normalized. No difference in stress-strain relation was observed among groups or before and after weight loss. In conclusion, our data suggest that microvascular rarefaction occurs in obesity. EPCs were significantly reduced in obese patients. Pronounced weight loss induced by bariatric surgery seems to induce a significant improvement of EPC number, but not of capillary rarefaction. A pronounced fibrosis of subcutaneous small resistance arteries is present in obese patients, regardless of the presence of increased blood pressure values. Consistent weight loss induced by bariatric surgery may induce an almost complete regression of microvascular fibrosis.

The changes in the endothelial function and haemostatic and inflammatory parameters in subclinical and overt hyperthyroidism

Introduction. The aim of the present study was to compare the levels of circulating markers of endothelial function and low-grade inflammation in patients with subclinical and overt hyperthyroidism (OH) due to Graves disease (GD) and toxic nodular goiter (TNG). Material and Methods. The group studied consisted of 42 patients with GD, 75 patients with TNG, and 39 healthy controls. Results. Circulating markers of endothelial dysfunction were elevated in the patients with both SH and OH, but the concentrations of interleukin-12 (IL-12) (P < 0.05), IL-18 (P < 0.05), fibrinogen (P < 0.01), and von Willebrand factor (vWF) (P < 0.05) were significantly higher in the OH than in the SH group. The highest levels of IL-6, IL-12, IL-18, vWF, sVCAM-1, and fibrinogen were found in the patients with GD, but the differences between the GD, and TNG groups were not significant. In the subjects with OH serum IL-6 was positively associated with FT3 (R = 0.276, P < 0.05), FT4 (R = 0.273, P < 0.05), and thyroid peroxidase antibodies (R = 0.346, P < 0.01) levels. Conclusion. Our results may suggest that both SH and OH may be associated with endothelial dysfunction, which is reflected by decreased fibrinolytic activity, hypercoagulability, and increased levels of IL-6, IL-12, and IL-18 and depends not only on the cause but also on the degree of hyperthyroidism.

Relative levels of the inflammatory cytokine TNFα and the soluble CD40 ligand profile in serum correlate with the thyrotoxic activity of Graves' disease

BACKGROUND

Interactions between CD40 and its ligand (CD40L) have important roles in T-cell-dependent activation of B cells, which may be related to the thyrotoxic activity of Graves' disease (GD). Soluble forms of CD40 ligand (sCD40L) are released from activated T cells and platelets, and several types of inflammatory cytokines are increased in patients with hyperthyroid GD. The aim of this study was to assess sCD40L and other cytokines as clinical indicators of disease activity or as possible markers of remission in GD.

METHODS

Serum levels of sCD40L, interleukin 18 (IL-18), tumor necrosis factor-alpha (TNFα), and TNFα receptors 1 and 2 (TNFR1 and TNFR2) were investigated in patients with active GD (GD-A), intractable GD (GD-IT), inactive GD (GD-IA), GD in remission (GD-R), and Hashimoto's thyroiditis (HT), and in control subjects (CON).

RESULTS

Serum concentrations of sCD40L were higher in the GD-A and GD-IT groups than in the HT and CON groups. Similarly, serum concentrations of IL-18, which induces Th1 cytokines, such as interferon-γ, were higher in the GD-A and GD-IT groups than in all other groups. Serum levels of TNFR1 and TNFR2 were also significantly higher in the GD-A than in all other groups. The mean serum concentration of TNFα was higher in the GD-R compared with the GD-A and GD-IT groups, although the difference was not significant. Serum sCD40L concentrations in the GD-R group were lower than in the GD-A and GD-IT groups. Finally, the ratio of serum TNFα to sCD40L was higher in the GD-R group than in the GD-A and GD-IT groups. This is the first report that serum sCD40L is increased in active GD, and that the serum TNFα:sCD40L ratio is a marker for remission in GD.

CONCLUSIONS

Our results suggest that not only thyrotoxicosis, but also the activity of the immunoreaction presenting as anti-thyrotropin receptor antibodies (TRAb) titer in GD, affects inflammatory cytokine serum profiles. Serum profiles of cytokines vary in patients with GD depending on disease activity. An elevated serum TNFα:sCD40L ratio indicates declining disease activity and reflects a shift from Th2 to Th1 dominance, suggesting that suppression of sCD40L or increased production of TNFα is required to initiate or maintain remission of GD.

Inflammasome activation of IL-18 results in endothelial progenitor cell dysfunction in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease with heterogeneous manifestations including severe organ damage and vascular dysfunction leading to premature atherosclerosis. IFN-α has been proposed to have an important role in the development of lupus and lupus-related cardiovascular disease, partly by repression of IL-1 pathways leading to impairments in vascular repair induced by endothelial progenitor cells (EPCs) and circulating angiogenic cells (CACs). Counterintuitively, SLE patients also display transcriptional upregulation of the IL-1β/IL-18 processing machinery, the inflammasome. To understand this dichotomy and its impact on SLE-related cardiovascular disease, we examined cultures of human and murine control or lupus EPC/CACs to determine the role of the inflammasome in endothelial differentiation. We show that caspase-1 inhibition improves dysfunctional SLE EPC/CAC differentiation into mature endothelial cells and blocks IFN-α-mediated repression of this differentiation, implicating inflammasome activation as a crucial downstream pathway leading to aberrant vasculogenesis. Furthermore, serum IL-18 levels are elevated in SLE and correlate with EPC/CAC dysfunction. Exogenous IL-18 inhibits endothelial differentiation in control EPC/CACs and neutralization of IL-18 in SLE EPC/CAC cultures restores their capacity to differentiate into mature endothelial cells, supporting a deleterious effect of IL-18 on vascular repair in vivo. Upregulation of the inflammasome machinery was operational in vivo, as evidenced by gene array analysis of lupus nephritis biopsies. Thus, the effects of IFN-α are complex and contribute to an elevated risk of cardiovascular disease by suppression of IL-1β pathways and by upregulation of the inflammasome machinery and potentiation of IL-18 activation.