Prognostic value of thyroid hormones in acute ischemic stroke - a meta analysis

The impact of thyroid disorder on cardiovascular disease: Unraveling the connection and implications for patient care

The thyroid gland is responsible for metabolism, as well as cardiac function and the peripheral vascular system. Thyroid dysfunctions are associated with an increase in the risk of cardiovascular diseases, including heart failure and coronary heart disease atrial fibrillation, by impairing heart contractility, stroke volume, heart rate, peripheral vascular resistance, and electrical activity. Thyroid dysfunctions also alter several cardiovascular risk factors, such as atherosclerosis, hypertension, and dyslipidemia, as well as causing stroke, which is associated with atrial fibrillation. An antiarrhythmic drug, amiodarone, may also induce both thyrotoxicosis and hypothyroidism, so its use requires serial thyroid function testing. Every CVD patient is recommended to be screened and treated for any possible thyroid dysfunction to reduce the patient's mortality and morbidity.

Causal role of thyroid function in functional outcome after ischemic stroke: A Mendelian randomization study

BACKGROUND

Previous observational studies have suggested that thyroid function may be associated with functional outcome after ischemic stroke (IS). Nevertheless, the causal relationship remains unclear. This study aimed to explore the causal effect of thyroid function [thyroid-stimulating hormone (TSH), free thyroxine (FT4), hyperthyroidism, and hypothyroidism] on functional outcome (based on the modified Rankin scale) after IS by two-sample Mendelian randomization (MR) analysis.

METHODS

Inverse variance weighted (IVW) was the primary method for evaluating causal associations. In addition, six additional MR methods (MR-Egger regression, weighted median, maximum likelihood, simple mode, weighted mode, and MR-PRESSO) were employed to supplement IVW. Furthermore, various sensitivity tests were conducted to assess the reliability: (i) Cochrane's Q test for assessing heterogeneity; (ii) MR-Egger intercept test and MR-PRESSO global test for evaluating horizontal pleiotropy; (iii) leave-one-out sensitivity test for determining stability.

RESULTS

The results of IVW indicated that elevated TSH levels significantly improved functional outcome after IS (OR = 0.74, 95 % CI: 0.57-0.97, P = 0.028). In addition, six additional MR methods suggested parallel results. However, no causal effect of FT4, hyperthyroidism, and hypothyroidism on functional outcome after IS was identified. In addition, sensitivity tests demonstrated the reliability of the MR analyses, suggesting that the MR analysis was not influenced by significant heterogeneity and horizontal pleiotropy.

CONCLUSIONS

Our MR study supported that elevated TSH levels might improve functional outcome after IS. Therefore, regular monitoring and maintenance of stable TSH levels may benefit patients recovering from IS.

What is the impact of acute endocrine and metabolic alterations on long-term ischemic stroke prognosis: a prospective study

BACKGROUND

Post-stroke stress can trigger instant survival but its influence on long-term ischemic stroke outcomes remains controversial. Thus, we sought to explore the associations of acute post-stroke stress evidenced by endocrine and metabolic changes, with long-term ischemic stroke outcomes.

METHODS

Admissions for acute ischemic stroke within seven days of onset were prospectively recruited to determine acute endocrine and metabolic variations measured by thyroid parameters and the stress hyperglycemia ratio (SHR). Long-term ischemic stroke prognoses were followed up for one year, with the primary outcome being a modified Rankin Scale score of 3 to 6.

RESULTS

A total of 887 patients were enrolled, of which 535 reached the final one-year followed up at a poor prognosis rate of 29.3%. Patients with poor outcomes were observed to have lower levels of free triiodothyronine (fT3) and higher levels of SHR on admission. Medium values (fT3, 4.4 mmol/L; SHR, 8 nmol/L) were used to divide patients into four gradient stress degrees. Larger acute endocrine and metabolic variations (fT3 < 4.4 mmol/L and SHR ≥ 8 nmol/L) were independently associated with a poor one-year prognosis (adjusted OR = 4.231, P = 0.001).

CONCLUSIONS

High degrees of acute post-stroke stress may aggravate long-term ischemic stroke prognosis and timely stress-reduced interventions may help promote post-stroke living quality is equally important as survival.

Thyroid hormones and stroke, the gap between clinical and experimental studies

Despite plenty of human studies on changes in thyroid hormones after stroke and some animal studies that assessed the effects of thyroid hormone administration on stroke, conclusive evidence for clinical application is lacking. This review aimed to determine the consistency of the results between clinical and preclinical studies. This article reviewed the PubMed, Embase, web of Knowledge, and Google Scholar databases up to June 2023 using the MeSH terms "stroke, cerebral ischemia, cerebral infarction, brain ischemia, brain infarction, triiodothyronine (T3), tetraiodothyronine (T4), thyroxine (T4), and thyroid hormone". The results of clinical and preclinical studies related to T3 substantially confirm each other. That is, in most human studies lower T3 was associated with poor outcomes, and in experimental studies, T3 administration also had therapeutic effects. However, the results of experimental studies related to T4 could not support those of clinical studies. There seem to be some conflicts between experimental and human studies, especially regarding changes and effects of T4 after stroke. The gap between experimental and clinical studies may lead to non-applicable results, wasting time and money, and unnecessary killing of animals.

Impact of thyroid hormone replacement therapy on the course and functional outcome of aneurysmal subarachnoid hemorrhage

BACKGROUND

Thyroid hormones were reported to exert neuroprotective effects after ischemic stroke by reducing the burden of brain injury and promoting post-ischemic brain remodeling.

OBJECTIVE

We aimed to analyze the value of thyroid hormone replacement therapy (THRT) due to pre-existing hypothyroidism on the clinical course and outcome of aneurysmal subarachnoid hemorrhage (SAH).

METHODS

SAH individuals treated between January 2003 and June 2016 were included. Data on baseline characteristics of patients and SAH, adverse events and functional outcome of SAH were recorded. Study endpoints were cerebral infarction, in-hospital mortality and unfavorable outcome at 6 months. Associations were adjusted for outcome-relevant confounders.

RESULTS

109 (11%) of 995 individuals had THRT before SAH. Risk of intracranial pressure- or vasospasm-related cerebrovascular events was inversely associated with presence of THRT (p = 0.047). In multivariate analysis, THRT was independently associated with lower risk of cerebral infarction (adjusted odds ratio [aOR] = 0.64, 95% confidence interval [CI] = 0.41-0.99, p = 0.045) and unfavorable outcome (aOR = 0.50, 95% CI = 0.28-0.89, p = 0.018), but not with in-hospital mortality (aOR = 0.69, 95% CI = 0.38-1.26, p = 0.227).

CONCLUSION

SAH patients with THRT show lower burden of ischemia-relevant cerebrovascular events and more favorable outcome. Further experimental and clinical studies are required to confirm our results and elaborate the mechanistic background of the effect of THRT on course and outcome of SAH.

Genetics of ischemic stroke functional outcome

Ischemic stroke, which accounts for 87% of cerebrovascular accidents, is responsible for massive global burden both in terms of economic cost and personal hardship. Many stroke survivors face long-term disability-a phenotype associated with an increasing number of genetic variants. While clinical variables such as stroke severity greatly impact recovery, genetic polymorphisms linked to functional outcome may offer physicians a unique opportunity to deliver personalized care based on their patient's genetic makeup, leading to improved outcomes. A comprehensive catalogue of the variants at play is required for such an approach. In this review, we compile and describe the polymorphisms associated with outcome scores such as modified Rankin Scale and Barthel Index. Our search identified 74 known genetic polymorphisms spread across 48 features associated with various poststroke disability metrics. The known variants span diverse biological systems and are related to inflammation, vascular homeostasis, growth factors, metabolism, the p53 regulatory pathway, and mitochondrial variation. Understanding how these variants influence functional outcome may be helpful in maximizing poststroke recovery.

Hyperthyroidism and cardiovascular disease: an association study using big data analytics

BACKGROUND

The cardiovascular (CV) system is profoundly affected by thyroid hormones. Both hypo- and hyperthyroidism can increase the risk of severe CV complications.

OBJECTIVE

To assess the association of hyperthyroidism with major CV risk factors (CVRFs) and CV diseases (CVDs) using a big data methodology with the Savana Manager platform.

MATERIAL AND METHODS

This was an observational and retrospective study. The data were obtained from the electronic medical records of the University Hospital Puerta de Hierro Majadahonda (Spain). Artificial intelligence techniques were used to extract the information from the electronic health records and Savana Manager 3.0 software was used for analysis.

RESULTS

Of a total of 540,939 patients studied (53.62% females; mean age 42.2 ± 8.7 years), 5504 patients (1.02%; 69.9% women) had a diagnosis of hyperthyroidism. Patients with this diagnosis had a significantly (p < 0.0001) higher frequency of CVRFs than that found in non-hyperthyroid subjects. The higher frequency of CVRFs in patients with hyperthyroidism was observed in both women and men and in patients younger and older than 65 years of age. The total frequency of CVDs was also significantly (p < 0.0001) higher in patients diagnosed with hyperthyroidism than that found in patients without this diagnosis. The highest odds ratio values obtained were 6.40 (4.27-9.61) for embolic stroke followed by 5.99 (5.62-6.38) for atrial fibrillation. The frequency of all CVDs evaluated in patients with a diagnosis of hyperthyroidism was significantly higher in both women and men, as well as in those younger and older than 65 years, compared to subjects without this diagnosis. A multivariate regression analysis showed that hyperthyroidism was significantly and independently associated with all the CVDs evaluated except for embolic stroke.

CONCLUSION

The data from this hospital cohort suggest that there is a significant association between the diagnosis of hyperthyroidism and the main CVRFs and CVDs in our population, regardless of the age and gender of the patients. Our study, in addition to confirming this association, provides useful information for understanding the applicability of artificial intelligence techniques to "real-world data and information".

Association of thyroid hormone sensitivity index with stroke in patients with coronary artery disease

BACKGROUND AND AIMS

Thyroid hormones (THs) will affect the occurrence and prognosis of stroke, and the research on THs sensitivity index and stroke in patients with coronary heart disease (CHD) is scarce. The goal of this study is to look into the relationship between central and peripheral THs sensitivity index and stroke in patients with CHD.

METHODS

Between January 1, 2014, and September 30, 2020, 30,160 patients with CHD were enrolled in this study. By computing the thyroid feedback quantile index (TFQI), thyroid stimulating hormone index (TSHI), and thyrotropin thyroxine resistance index (TT4RI), the central sensitivity indexes to THs was assessed, and the ratio of serum free triiodothyronine (FT3) to serum free thyroxine (FT4) was used to assess peripheral THs sensitivity. The relationship between central and peripheral THs sensitivity index and stroke was investigated using logistic regression, especially in different types of stroke, ages, sexes, and blood glucose levels.

RESULTS

Stroke risk is positive associated with TSHI, TFQI, and PTFQI. In subgroup analysis, the OR values of these relationships are higher in people younger than 65 years old, male, and diagnosed with diabetes. In addition, stroke risk was negatively associated with FT3/FT4, and the OR values of these relationships were lower in people older than 65 years, female, and diagnosed with prediabetes.

CONCLUSIONS

This study demonstrates that the increase in the central THs sensitivity index and the decrease in the peripheral THs sensitivity index are associated with a higher risk of stroke in CHD patients, and provides new ideas for the assessment of stroke in patients with CHD.

Association between thyroid hormone levels in the acute stage of stroke and risk of poststroke depression: A meta-analysis

BACKGROUND

Thyroid hormones have been indicated to be associated with depression, but their relationship with poststroke depression (PSD) remains controversial. Therefore, we performed a meta-analysis to explore the correlation between thyroid hormone levels in acute stroke and PSD.

METHODS

We searched databases for eligible studies. Standard mean differences (SMD) and 95% confidence intervals (CI) were applied to evaluate the association among levels of thyroid hormones, including thyroid-stimulating hormone (TSH), free triiodothyronine (FT3), and free thyroxine (FT4), in acute stroke patients and the risk of PSD.

RESULTS

A total of 13 studies were included in the analysis. Compared to non-PSD patients, PSD patients had remarkably lower serum TSH and FT3 levels (TSH: SMD = -0.59, 95%CI = -1.04 to -.15, p = .009; FT3: SMD = -0.40, 95%CI = -.51 to -.30, p = .000) and higher serum FT4 levels (SMD = 0.33, 95%CI = .07-.59, p = .013). Subgroup analysis showed that there may be a more statistically significant association between FT3 and the risk of PSD compared to TSH and FT4.

CONCLUSIONS

Our results suggested that patients with lower serum TSH and FT3 levels as well as higher serum FT4 levels in the acute stage of stroke may be more susceptible to PSD.

Preserving and enhancing mitochondrial function after stroke to protect and repair the neurovascular unit: novel opportunities for nanoparticle-based drug delivery

The neurovascular unit (NVU) is composed of vascular cells, glia, and neurons that form the basic component of the blood brain barrier. This intricate structure rapidly adjusts cerebral blood flow to match the metabolic needs of brain activity. However, the NVU is exquisitely sensitive to damage and displays limited repair after a stroke. To effectively treat stroke, it is therefore considered crucial to both protect and repair the NVU. Mitochondrial calcium (Ca2+) uptake supports NVU function by buffering Ca2+ and stimulating energy production. However, excessive mitochondrial Ca2+ uptake causes toxic mitochondrial Ca2+ overloading that triggers numerous cell death pathways which destroy the NVU. Mitochondrial damage is one of the earliest pathological events in stroke. Drugs that preserve mitochondrial integrity and function should therefore confer profound NVU protection by blocking the initiation of numerous injury events. We have shown that mitochondrial Ca2+ uptake and efflux in the brain are mediated by the mitochondrial Ca2+ uniporter complex (MCUcx) and sodium/Ca2+/lithium exchanger (NCLX), respectively. Moreover, our recent pharmacological studies have demonstrated that MCUcx inhibition and NCLX activation suppress ischemic and excitotoxic neuronal cell death by blocking mitochondrial Ca2+ overloading. These findings suggest that combining MCUcx inhibition with NCLX activation should markedly protect the NVU. In terms of promoting NVU repair, nuclear hormone receptor activation is a promising approach. Retinoid X receptor (RXR) and thyroid hormone receptor (TR) agonists activate complementary transcriptional programs that stimulate mitochondrial biogenesis, suppress inflammation, and enhance the production of new vascular cells, glia, and neurons. RXR and TR agonism should thus further improve the clinical benefits of MCUcx inhibition and NCLX activation by increasing NVU repair. However, drugs that either inhibit the MCUcx, or stimulate the NCLX, or activate the RXR or TR, suffer from adverse effects caused by undesired actions on healthy tissues. To overcome this problem, we describe the use of nanoparticle drug formulations that preferentially target metabolically compromised and damaged NVUs after an ischemic or hemorrhagic stroke. These nanoparticle-based approaches have the potential to improve clinical safety and efficacy by maximizing drug delivery to diseased NVUs and minimizing drug exposure in healthy brain and peripheral tissues.

Neuroendocrine regulation in stroke

The neuroendocrine system, a crosstalk between the central nervous system and endocrine glands, balances and controls hormone secretion and their functions. Neuroendocrine pathways and mechanisms often get dysregulated following stroke, leading to altered hormone secretion and aberrant receptor expression. Dysregulation of the hypothalamus-pituitary-thyroid (HPT) axis and hypothalamus-pituitary-adrenal (HPA) axis often led to severe stroke outcomes. Post-stroke complications such as cognitive impairment, depression, infection etc. are directly or indirectly influenced by the altered neuroendocrine activity that plays a crucial role in stroke vulnerability and susceptibility. Therefore, it is imperative to explore various neurohormonal inter-relationships in regulating stroke, its outcome, and prognosis. Here, we review the biology of different hormones associated with stroke and explore their regulation with a view towards prospective therapeutics.

Thyroid stimulating hormone correlates with triglyceride levels but is not associated with the severity of acute ischemic stroke in patients with euthyroidism: a cross-sectional study

Background

Growing evidence suggests an association between thyroid stimulating hormone (TSH) and severity of acute ischemic stroke (AIS). However, few studies have ruled out the potential influences of abnormal thyroid hormones when assessing this association. This study aimed to investigate the association between TSH levels and the severity of AIS patients with euthyroidism, and to explore the potential mechanism of TSH on this disease by analyzing the correlation of TSH with lipid profiles.

Methods

This retrospective study consisted of 345 patients with normal T3 and T4 levels admitted for first-ever cerebral ischemic stroke. Baseline data of participant were collecte. Laboratory data, including serum levels of TSH and lipid profiles were measured in our hospital's clinical laboratory on admission. Stroke severity was recorded using the National Institutes of Health Stroke Scale (NIHSS). Associations between TSH levels and disease severity were analyzed with logistic regression analysis. Correlations between TSH and lipid profiles were analyzed with Spearman's rank correlation analysis.

Results

Among the 345 patients with AIS, the median age was 63 years (63±12 years), 106 patients (30.7%) were female, 237 (68.7%) patients were mild-severity and 108 (31.3%) patients were severity. Data analysis showed that higher serum TSH levels were associated with the mild severity of patients with AIS (P=0.042 in Kruskal-Wallis test, P=0.025 in logistic regression analysis, and P=0.044 in multiple logistic regression), but not in AIS patients with euthyroidism (P=0.078, P=0.337, respectively). Furthermore, TSH levels were correlated with triglycerides (TG) levels not only in total patients (r=0.135, P=0.012) but also in the patients with euthyroidism (r=0.133, P=0.018).

Conclusions

TSH levels are associated with the severity of AIS patients, but not in patients with euthyroidism, predicting that stratified management of TSH may be beneficial in patients with AIS. Moreover, TSH levels are correlated with TG levels in patients with AIS.

Thyroid hormone levels paradox in acute ischemic stroke

Objective

Accumulating evidence has suggested that thyroid hormone levels affect the prognosis of acute ischemic stroke (AIS), but the results have been inconsistent.

Methods

Basic data, neural scale scores, thyroid hormone levels, and other laboratory examination data of AIS patients were collected. The patients were divided into excellent and poor prognosis group at discharge and 90 days after discharge. Logistic regression models were applied to evaluate the relationship between thyroid hormone levels and prognosis. A subgroup analysis was performed based on stroke severity.

Results

A number of 441 AIS patients were included in this study. Those in the poor prognosis group were older, with higher blood sugar levels, higher free thyroxine (FT4) levels, and severe stroke (all p < 0.05) at baseline. Free thyroxine (FT4) showed a predictive value (all p < 0.05) for prognosis in the model adjusted for age, gender, systolic pressure, and glucose level. However, after adjustment for types and severity of stroke, FT4 showed insignificant associations. In the severe subgroup at discharge, the change in FT4 was statistically significant (p = 0.015), odds ratio (95% confidence interval) = 1.394 (1.068-1.820) but not in the other subgroups.

Conclusions

High-normal FT4 serum levels in patients with severe stroke receiving conservative medical treatment at admission may indicate a worse short-term prognosis.

Cardiovascular and Neuronal Consequences of Thyroid Hormones Alterations in the Ischemic Stroke

Ischemic stroke is one of the leading global causes of neurological morbidity and decease. Its etiology depends on multiple events such as cardiac embolism, brain capillaries occlusion and atherosclerosis, which ultimately culminate in blood flow interruption, incurring hypoxia and nutrient deprivation. Thyroid hormones (THs) are pleiotropic modulators of several metabolic pathways, and critically influence different aspects of tissues development. The brain is a key TH target tissue and both hypo- and hyperthyroidism, during embryonic and adult life, are associated with deranged neuronal formation and cognitive functions. Accordingly, increasing pieces of evidence are drawing attention on the consistent relationship between the THs status and the acute cerebral and cardiac diseases. However, the concrete contribution of THs systemic or local alteration to the pathology outcome still needs to be fully addressed. In this review, we aim to summarize the multiple influences that THs exert on the brain and heart patho-physiology, to deepen the reasons for the harmful effects of hypo- and hyperthyroidism on these organs and to provide insights on the intricate relationship between the THs variations and the pathological alterations that take place after the ischemic injury.

Research progress on the role of hormones in ischemic stroke

Ischemic stroke is a major cause of death and disability around the world. However, ischemic stroke treatment is currently limited, with a narrow therapeutic window and unsatisfactory post-treatment outcomes. Therefore, it is critical to investigate the pathophysiological mechanisms following ischemic stroke brain injury. Changes in the immunometabolism and endocrine system after ischemic stroke are important in understanding the pathophysiological mechanisms of cerebral ischemic injury. Hormones are biologically active substances produced by endocrine glands or endocrine cells that play an important role in the organism's growth, development, metabolism, reproduction, and aging. Hormone research in ischemic stroke has made very promising progress. Hormone levels fluctuate during an ischemic stroke. Hormones regulate neuronal plasticity, promote neurotrophic factor formation, reduce cell death, apoptosis, inflammation, excitotoxicity, oxidative and nitrative stress, and brain edema in ischemic stroke. In recent years, many studies have been done on the role of thyroid hormone, growth hormone, testosterone, prolactin, oxytocin, glucocorticoid, parathyroid hormone, and dopamine in ischemic stroke, but comprehensive reviews are scarce. This review focuses on the role of hormones in the pathophysiology of ischemic stroke and discusses the mechanisms involved, intending to provide a reference value for ischemic stroke treatment and prevention.

Thyroid hormone decreasing after mechanical thrombectomy for cerebral infarction

OBJECTIVE

Mechanical thrombectomy (MT) is an established treatment for large vessel occlusion in patients with cerebral infarction. The use of iodine contrast agent decreases thyroid hormone levels via the Wolff-Chaikoff effect. Low triiodothyronine (T3) syndrome caused due to severe illness status can contribute to decreased levels of thyroid hormones. Reportedly, a low T3 level is associated with poor prognosis in patients with cerebral infarction. This study aimed to clarify the changes in thyroid hormone levels in the acute phase after MT and the effects of the iodine contrast agent on these hormones.

METHODS

This was a single-center, prospective, and single-arm trial. Thyroid stimulating hormone (TSH), free T3 (FT3), and free T4 (FT4) levels were tested on admission and 24 h postoperatively in patients who were approved for MT.

RESULTS

A total of 37 patients were screened during the study period and 31 patients were enrolled in this study. Significant decreases were observed in TSH (P < 0.001) and FT3 (P < 0.001) levels 24 h after MT. Moreover, there was a correlation between the decrease in ratio of change in FT3 levels and the amount of iodine contrast agent used per body surface area (r = 0.43, P = 0.019), while no such correlations were detected for TSH and FT4.

CONCLUSION

We demonstrated that TSH and FT3 levels decreased in the acute phase after MT and that FT3 levels were associated with the amount of iodine contrast agent used.

Thyroid Hormone Levels Help to Predict Outcome of Critically Ill Patients Undergoing Early Neurological Rehabilitation

The present study was aimed at examining thyroid hormones and other clinical factors to improve the accuracy of outcome prediction among critically ill patients undergoing early neurological rehabilitation. Patients consecutively admitted to an intensive or intermediate care unit were screened for eligibility. Serum levels of free triiodothyronine (fT3), free thyroxine (fT4), and thyroid-stimulating hormone (TSH) were collected during the first three days after admission. The Glasgow Outcome Scale (GOS) was defined as the primary outcome measure. Thyroid hormone levels and other clinical factors were entered into a binary logistic regression model to predict a good outcome at the end of early rehabilitative treatment. 395 patients (268 males) with a median age of 62 years (IQR = 52 − 76) and a median disease duration of 19 days (IQR = 13 − 28) were included in the study. Most patients (80%) had decreased fT3 values. Patients with low fT3 were admitted earlier to the rehabilitation facility and had more severe impairment upon admission compared to patients with fT3 values within the normal range. Both decreased fT3 and TSH levels were associated with an unfavorable outcome (GOS ≤ 3), but only TSH proved to be an independent predictor in multivariate analyses (OR = 1.11; 95%CI = 1.02 − 1.22). These data suggest that decreased fT3 and TSH levels upon admission may predict an unfavorable outcome at the end of early rehabilitative treatment. Thus, thyroid hormone levels are not only important during acute treatment but also in prolonged critical illness.

Association of thyroid function, within the euthyroid range, with cardiovascular risk: The EPIPorto study

BACKGROUND

Thyroid hormones are important modulators of cardiovascular function. Both hypothyroidism and hyperthyroidism are known to contribute to an increased cardiovascular risk. It remains uncertain whether thyroid hormones level within the euthyroid range are associated with cardiometabolic risk. We aimed to evaluate the association between thyroid function levels within the euthyroid range and cardiovascular risk in a population-based cohort.

METHODS

Eight hundred thirty-five subjects aged ≥45 years from the EPIPorto population-based cohort were included. We excluded participants with TSH, free T4 (FT4), or free T3 (FT3) outside of the reference range, or with previous cardiovascular or thyroid disease. The associations between thyroid function, cardiovascular risk factors and the 10-year estimated risk of cardiovascular events (using SCORE2 and SCORE2-OP) were evaluated in linear and logistic regression models, crudely and adjusting for age, sex, BMI, diabetes, and smoking.

RESULTS

The mean age of the participants was 61.5 (SD 10.5) years and 38.9% were men. Eleven percent of the participants had diabetes, 47.8% had dyslipidemia, and 54.8% had hypertension. The mean body mass index (BMI) was 27.4 (SD 4.6) kg/m², and the median (percentile25-75) 10-year risk of cardiovascular events was 5.46% (2.92, 10.11). Participants with higher BMI, larger waist circumference and higher hs-CRP had higher levels of FT3 and FT3/FT4 ratio. Lower FT3/FT4 ratio and higher FT4 levels were associated with higher prevalence of diabetes and more adverse lipid profile. Higher TSH, lower FT3 and lower FT3/FT4 ratio were associated with lower eGFR. Lower FT3, lower FT3/FT4 ratio and higher FT4 were associated with an increased 10-year risk of cardiovascular events.

CONCLUSIONS

In a population-based study, variations of thyroid function within the euthyroid range were associated with cardiovascular risk factors. On one hand, individuals with higher BMI, larger waist circumference and higher hs-CRP had higher levels of FT3 and FT3/FT4 ratio. On the other hand, a decreased conversion of T4 to T3 (lower FT3, lower FT3/FT4 ratio and/or higher FT4) was associated with a higher prevalence of diabetes, a more adverse lipid profile, a lower eGFR and an increased 10-year risk of cardiovascular events.

Repetitive Transcranial Magnetic Stimulation (rTMS) Modulates Thyroid Hormones Level and Cognition in the Recovery Stage of Stroke Patients with Cognitive Dysfunction

Background

This single-center study aimed to investigate the effects of repetitive transcranial magnetic stimulation (rTMS) on modulation of thyroid hormone levels and cognition in the recovery stage of patients with cognitive dysfunction following stroke.

Material/Methods

Seventy post-stroke patients who had cognitive impairment were randomly assigned to either the rTMS group or the control (sham) group. Both groups were administered basic treatment, with the rTMS group receiving rTMS (1 Hz, 90% MT, 1000 pulse/20 min, once a day for 5 days, for a total of 20 times), the stimulation site was the contralateral dorsolateral prefrontal cortex (DLPFC), and the sham group receiving sham stimulation which had the same stimulation parameters and site, except that the coil plane was placed perpendicular to the surface of the scalp. Cognitive function assessment and thyroid function tests were performed before and after 4 weeks of treatment.

Results

Serum levels of triiodothyronine (T3), free triiodothyronine (FT3), and thyroid stimulating hormone (TSH) showed a positive correlation with Montreal Cognitive Assessment (MoCA) scale score of stroke patients in the recovery phase. The post-treatment change in the scores of MoCA and Modified Barthel Index (MBI) and scores of 3 cognitive domains (visuospatial function, memory, and attention), as well as serum T3, FT3, and TSH levels, were improved more significantly in the rTMS group, and T3 and FT3 levels significantly affected the MoCA scores within the reference range.

Conclusions

Serum T3, FT3, and TSH levels of stroke patients in the recovery phase were positively correlated with MoCA score. rTMS increased T3, FT3, and TSH levels and also improved MoCA and MBI of patients in the recovery phase of stroke.

Relationship between Blood Trihalomethane Concentrations and Serum Thyroid Function Measures in U.S. Adults

Toxicological studies show that exposure to disinfection byproducts, including trihalomethanes (THMs), negatively affects thyroid function; however, few epidemiological studies have explored this link. This study included 2233 adults (ages ≥20 years) from the 2007-2008 National Health and Nutrition Examination Survey (NHANES) who were measured for blood THM concentrations [chloroform (TCM), bromodichloromethane (BDCM), dibromochloromethane (DBCM), or bromoform (TBM)] and serum thyroid function biomarkers [thyroid-stimulating hormone, free thyroxine (FT4), total thyroxine (TT4), free triiodothyronine (FT3), total triiodothyronine (TT3), thyroid peroxidase antibody (TPOAb), and thyroglobulin antibody (TgAb)]. Multivariable linear regression models showed positive associations between blood TCM, BDCM, and total THMs (the sum of all four THMs) concentrations and serum FT4, whereas inverse associations were found between blood DBCM and total brominated THM (Br-THM; the sum of BDCM, DBCM, and TBM) concentrations and serum TT3 (all p < 0.05). Besides, positive associations were observed between blood TCM concentrations and FT4/FT3 ratio, between BDCM, DBCM, and Br-THM concentrations and TT4/TT3 ratio, and between DBCM and Br-THM concentrations and FT3/TT3 ratio (all p < 0.05). Blood THM concentrations were unrelated to the serum levels of thyroid autoantibodies TgAb or TPOAb. In summary, exposure to THMs was associated with altered serum biomarkers of thyroid function but not with thyroid autoimmunity among U.S. adults.

Brain to periphery in acute ischemic stroke: Mechanisms and clinical significance

The social and public health burdens of ischemic stroke have been increasing worldwide. In addition to focal brain damage, acute ischemic stroke (AIS) provokes systemic abnormalities across peripheral organs. AIS profoundly alters the autonomic nervous system, hypothalamic-pituitary-adrenal axis, and immune system, which further yield deleterious organ-specific consequences. Poststroke systemic pathological alterations in turn considerably contribute to the progression of ischemic brain injury, which accounts for the substantial impact of systemic complications on stroke outcomes. This review provides a comprehensive and updated pathophysiological model elucidating the systemic effects of AIS. To address their clinical significance and inform stroke management, we also outline the resulting systemic complications at particular stages of AIS and highlight the mechanisms. Future therapeutic strategies should attempt to integrate the treatment of primary brain lesions with interventions for secondary systemic complications, and should be tailored to patient individualized characteristics to optimize stroke outcomes.

Serum total triiodothyronine (T3) as a predictor of mortality and morbidity in critically ill patients and its correlation of predictability with acute physiology and chronic health evaluation II score: A prospective observational study

Background:

The aim is to assess the prognostic value of total T3, total T4, and thyroid-stimulating hormone among critically ill patients admitted to the medical intensive care unit (ICU) in association with mortality and its correlation with the acute physiology and chronic health evaluation II (APACHE II) score.

METHODS

: Our prospective observational study consists of 257 patients without known thyroid diseases admitted to the medical ICU. The baseline characteristics of the patients were recorded, including the APACHE II score and thyroid hormone levels at ICU admission. Based on the primary outcome of mortality, we analyzed the data by appropriate statistical methods. A P < 0.05 was considered significant.

Results:

Of the 257 patients included in the study, 47 (18.28%) succumbed to their illnesses. A significant difference in T3 levels (P < 0.001), T4 levels (P < 0.001), and APACHE II score (P < 0.001) was found between the survivors and the nonsurvivors. There was negative correlation observed between T3 and APACHE II score (r = −0.448, P < 0.001) and T4 and APACHE II score (r = −0.221, P ≤ 0.001). Multivariate logistic regression analysis determined T3 to be the only independent predictor of ICU mortality among thyroid hormones. The area under the curve (AUC) for T3 (0.811 ± 0.04) was almost equal to that of the APACHE II score (0.858 ± 0.029). The duration of ICU stay and hospital stay in patients with low T3 was significantly higher compared to patients with normal T3.

Conclusion:

Serum T3 is a good indicator for predicting mortality and morbidity among critically ill patients.

The Role of Thyroid Hormone in Neuronal Protection

Thyroid hormone is essential for brain development and brain function in the adult. During development, thyroid hormone acts in a spatial and temporal-specific manner to regulate the expression of genes essential for normal neural cell differentiation, migration, and myelination. In the adult brain, thyroid hormone is important for maintaining normal brain function. Thyroid hormone excess, hyperthyroidism, and thyroid hormone deficiency, hypothyroidism, are associated with disordered brain function, including depression, memory loss, impaired cognitive function, irritability, and anxiety. Adequate thyroid hormone levels are required for normal brain function. Thyroid hormone acts through a cascade of signaling components: activation and inactivation by deiodinase enzymes, thyroid hormone membrane transporters, and nuclear thyroid hormone receptors. Additionally, the hypothalamic-pituitary-thyroid axis, with negative feedback of thyroid hormone on thyrotropin-releasing hormone (TRH) and thyroid-stimulating hormone (TSH) secretion, regulates serum thyroid hormone levels in a narrow range. Animal and human studies have shown both systemic and local reduction in thyroid hormone availability in neurologic disease and after brain trauma. Treatment with thyroid hormone and selective thyroid hormone analogs has resulted in a reduction in injury and improved recovery. This article will describe the thyroid hormone signal transduction pathway in the brain and the role of thyroid hormone in the aging brain, neurologic diseases, and the protective role when administered after traumatic brain injury. © 2021 American Physiological Society. Compr Physiol 11:1-21, 2021.

Cerebrovascular risk factors associated with ischemic stroke in a young non-diabetic and non-hypertensive population: a retrospective case-control study

Background

Globally, rates of ischemic stroke (IS) have been rising among young adults. This study was designed to identify risk factors associated with IS incidence in young adults unaffected by hypertension or diabetes.

Methods

This was a retrospective case-control study of early-onset IS patients without diabetes and hypertension. Control patients were matched with healthy individuals based upon sex, age (±2 years), and BMI (±3 kg/m²) at a 1:3 ratio. Sociodemographic, clinical, and risk factor-related data pertaining to these patients was collected. The association between these risk factors and IS incidence was then assessed using conditional logistic regression models.

Results

We recruited 60 IS patients and 180 controls with mean ages of 44.37 ± 4.68 and 44.31 ± 4.71 years, respectively, for this study. Relative to controls, IS patients had significantly higher total cholesterol (TG), homocysteine (HCY), white blood cell (WBC), absolute neutrophil count (ANC), systolic blood pressure (SBP), and diastolic blood pressure (DBP) levels, and significantly lower high-density lipoprotein cholesterol (HDL-C) and triglyceride cholesterol (TC), free triiodothyronine (FT3), and free thyroxine (FT4) levels (all P < 0.05). After controlling for potential confounding factors, HCY and ANC were found to be significantly positively associated with IS incidence (OR 1.518, 95%CI 1.165–1.977, P = 0.002 and OR 2.418, 95%CI 1.061–5.511, P = 0.036, respectively), whereas HDL-C and FT3 levels were negatively correlated with IS incidence (OR 0.001, 95%CI 0.000–0.083, P = 0.003 and OR 0.053, 95%CI 0.008–0.326, P = 0.002, respectively).

Conclusions

In young non-diabetic and non-hypertensive patients, lower HDL-C and FT3 levels and higher HCY and ANC levels may be associated with an elevated risk of IS. Additional prospective studies of large patient cohorts will be essential to validate these findings.

Transient expression of thyrotropin releasing hormone peptide and mRNA in the rat hippocampus following global cerebral ischemia/reperfusion injury

INTRODUCTION

The role of extra-hypothalamic thyrotropin-releasing hormone (TRH) has been investigated by pharmacological studies using TRH or its analogues and found to produce a wide array of effects in the central nervous system.

METHODS

Immunofluorescence, In situ labeling of DNA (TUNEL), in situ hybridization chain reaction and quantitative real-time polymerase chain reaction were used in this study.

RESULTS

We found that the granular cells of the dentate gyrus expressed transiently a significant amount of TRH-like immunoreactivity and TRH mRNA during the 6-24 h period following global cerebral ischemia/reperfusion injury. TUNEL showed that apoptosis of neurons in the CA1 region occurred from 48 h and almost disappeared at 7 days. TRH administration 30 min before or 24 h after the injury could partially inhibit neuronal loss, and improve the survival of neurons in the CA1 region.

CONCLUSION

These data suggest that endogenous TRH expressed transiently in the dentate gyrus of the hippocampus may play an important role in the survival of neurons during the early stage of ischemia/reperfusion injury and that delayed application of TRH still produced neuroprotection. This delayed application of TRH has a promising therapeutic significance for clinical situations.

Thyroid Hormone and Neural Stem Cells: Repair Potential Following Brain and Spinal Cord Injury

Neurodegenerative diseases are characterized by chronic neuronal and/or glial cell loss, while traumatic injury is often accompanied by the acute loss of both. Multipotent neural stem cells (NSCs) in the adult mammalian brain spontaneously proliferate, forming neuronal and glial progenitors that migrate toward lesion sites upon injury. However, they fail to replace neurons and glial cells due to molecular inhibition and the lack of pro-regenerative cues. A major challenge in regenerative biology therefore is to unveil signaling pathways that could override molecular brakes and boost endogenous repair. In physiological conditions, thyroid hormone (TH) acts on NSC commitment in the subventricular zone, and the subgranular zone, the two largest NSC niches in mammals, including humans. Here, we discuss whether TH could have beneficial actions in various pathological contexts too, by evaluating recent data obtained in mammalian models of multiple sclerosis (MS; loss of oligodendroglial cells), Alzheimer’s disease (loss of neuronal cells), stroke and spinal cord injury (neuroglial cell loss). So far, TH has shown promising effects as a stimulator of remyelination in MS models, while its role in NSC-mediated repair in other diseases remains elusive. Disentangling the spatiotemporal aspects of the injury-driven repair response as well as the molecular and cellular mechanisms by which TH acts, could unveil new ways to further exploit its pro-regenerative potential, while TH (ant)agonists with cell type-specific action could provide safer and more target-directed approaches that translate easier to clinical settings.

Deiodinases, organic anion transporter polypeptide polymorphisms and ischemic stroke outcomes

BACKGROUND

Ischemic stroke is a major cause of premature death and chronic disability worldwide, and individual variation in functional outcome is strongly influenced by genetic factors. Neuroendocrine signaling by the hypothalamic-hypophyseal-thyroid axis is a critical regulator of post-stroke pathogenesis, suggesting that allelic variants in thyroid hormone (TH) signaling can influence stroke outcome.

AIM

To examine associations between acute ischemic stroke (AIS) outcome and allelic variants of the TH metabolizing enzymes deiodinase type 1-3 (DIO1-3) and membrane transporting organic anion polypeptide C1 (OATP1C1).

METHODS

Eligible AIS patients from Lithuania (n = 248) were genotyped for ten DIO1-3 and OATP1C1 single nucleotide polymorphisms (SNPs): DIO1 rs12095080-A/G, rs11206244-C/T, and rs2235544-A/C; DIO2 rs225014-T/C and rs225015-G/A; DIO3 rs945006-T/G; OATP1C1 rs974453-G/A, rs10444412-T/C, rs10770704-C/T, and rs1515777-A/G. Functional outcome was evaluated one year after index AIS using the modified Rankin Scale. Analyses were adjusted for important confounders, including serum free triiodothyronine.

RESULTS

After adjustment for potential confounders, the major allelic (wild-type) DIO3 genotype rs945006-TT was associated with better 1-year AIS functional outcome (odds ratio [OR] = 0.25; 95% confidence interval [CI]: 0.08-0.74; p = .013), while the wild-type OATP1C1 genotype rs10770704-CC was associated with poorer outcome (OR = 2.00, 95%CI: 1.04-3.86; p = .038).

CONCLUSION

Allelic variants in thyroid axis genes may prove useful for prognosis and treatment guidance.

Common genetic variations of deiodinase genes and prognosis of brain tumor patients

BACKGROUND

Thyroid hormone (TH) metabolism can have prognostic significance in brain tumors. We studied the association of common variations in three deiodinase gene single-nucleotide polymorphisms (SNPs) with circulating TH concentrations and prognosis of brain tumor patients.

METHODS

Patients admitted for glioma and meningioma surgery between January, 2010 and September, 2011 were evaluated for functional status (Barthel Index or BI) and circulating free tri-iodothyronine (FT3), free thyroxine (FT4), and thyroid-stimulating hormone (TSH) concentrations. Ten common SNPs in the DIO1 gene; five SNPs in the DIO2 gene; and one SNP in the DIO3 gene were genotyped. Follow-up continued until November, 2017.

RESULTS

In glioblastoma patients, the DIO1 SNP rs2235544 CC genotype was associated with significantly lower risk of death at 2 years when compared to AA + CA genotypes after adjusting for patient gender, age, pre-operative functional status, adjuvant therapy, and extent of resection (HR = 0.34, 95% CI: 0.13-0.84, p = 0.019). The TT genotype vs. CC + TC genotypes of the DI02 SNP rs12885300 was associated with increased mortality risk after adjusting for patient gender, age, pre-operative functional status, adjuvant therapy, extent of resection, and FT3/FT4 (HR = 3.13, 95% CI: 1.20-8.16, p < 0.019). The C-allele of the DI01 SNP rs2235544 was related to increased circulating free T3/ free T4 ratio in glioma and meningioma patients, indicating greater T4 to T3 conversion.

CONCLUSIONS

SNPs of DIO1 gene (rs2235544) and DIO2 gene (rs12885300) have independent prognostic significance in glioblastoma patients. The C-allele of the DIO1 (rs2235544) is associated with greater T4 to T3 conversion.

Thyroid Hormones in the Brain and Their Impact in Recovery Mechanisms After Stroke

Thyroid hormones are of fundamental importance for brain development and essential factors to warrant brain functions throughout life. Their actions are mediated by binding to specific intracellular and membranous receptors regulating genomic and non-genomic mechanisms in neurons and populations of glial cells, respectively. Among others, mechanisms include the regulation of neuronal plasticity processes, stimulation of angiogenesis and neurogenesis as well modulating the dynamics of cytoskeletal elements and intracellular transport processes. These mechanisms overlap with those that have been identified to enhance recovery of lost neurological functions during the first weeks and months after ischemic stroke. Stimulation of thyroid hormone signaling in the postischemic brain might be a promising therapeutic strategy to foster endogenous mechanisms of repair. Several studies have pointed to a significant association between thyroid hormones and outcome after stroke. With this review, we will provide an overview on functions of thyroid hormones in the healthy brain and summarize their mechanisms of action in the developing and adult brain. Also, we compile the major thyroid-modulated molecular pathways in the pathophysiology of ischemic stroke that can enhance recovery, highlighting thyroid hormones as a potential target for therapeutic intervention.

Lower serum free triiodothyronine levels are associated with symptoms of depression after ischemic stroke

OBJECTIVE

Anxiety and depression symptoms are common after stroke. Changes in thyroid axis hormones have been reported to contribute to these symptoms in clinically euthyroid subjects with and without adjacent somatic pathology. This study aimed to determine associations between serum thyroid axis hormone levels, depression and anxiety symptoms in patients who experienced acute ischemic stroke (AIS).

METHODS

In total, 169 patients participated in the study. Serum thyroid stimulating hormone, free tetraiodothyronine (FT4) and free triiodothyronine (FT3) levels were assayed on admission and upon discharge from the hospital. Screening for anxiety and depression symptoms was performed with the Hospital Anxiety and Depression Scale twice - while in the hospital and at the end of rehabilitation course.

RESULTS

In the acute period after AIS, 19.2% of all patients showed symptoms of anxiety and 26.0% - symptoms of depression, while during the subacute period these proportions have increased up to 30.3% and 32.6%. No significant associations between thyroid axis hormones and anxiety were determined for both periods. Serum FT3 levels and FT3/FT4 ratio on admission were significantly lower in patients with symptoms of depression compared to those without. After controlling for possible confounders, lower serum FT3 levels remained significantly associated with higher odds of depression in the acute (OR = 1.85; 95% CI: 1.05-3.23, p = 0.03) and subacute periods (OR = 2.50; 95% CI: 1.06-5.88, p = 0.04) after AIS.

CONCLUSIONS

FT3 serum levels on admission while in the hospital as well as at the end of rehabilitation course may predict post-stroke depression symptoms.

Lower free triiodothyronine levels within the reference range are associated with higher cardiovascular mortality: An analysis of the NHANES

BACKGROUND

Thyroid hormones play a central role in cardiovascular homeostasis. Lower free triiodothyronine (FT3) levels have been associated with worse prognosis in several conditions. However, contrary to thyrotropin (TSH) and free thyroxine (FT4), the role of FT3 in morbidity and mortality in the general population remains uncertain. Our objective was to evaluate the association between within the normal range FT3 levels and mortality in the general population.

METHODS

We evaluated 7116 adults in the National Health and Nutrition Examination Survey (NHANES) 2001-2002, 2007-2008, and 2009-2010 cycles with mortality evaluated as of December 2011. Exclusion criteria were: pregnancy; history of thyroid disease; use of thyroid-related drugs; and TSH, FT4, or FT3 level outside the reference range.

RESULTS

During a median follow-up of 45 months, 357 participants died. In unadjusted analysis, lower FT3 levels were associated with higher all-cause (HR per 0.1 pg/mL increase in FT3: 0.82 [95% confidence interval, 0.78-0.87]), cardiovascular (HR 0.74 [0.66-0.83]), cancer-related (HR 0.88 [0.80-0.97]) and other cause-related mortality (HR 0.83 [0.77-0.90]). After adjustment with Cox proportional hazard models, lower FT3 levels remained significantly associated with higher cardiovascular mortality (HR 0.83 [0.75-0.93]), but not with all-cause (HR 0.97 [0.92-1.02]), cancer-related (HR 1.02 [0.89-1.17]), or other cause-related mortality (HR 1.00 [0.92-1.10]).

CONCLUSIONS

Lower levels of FT3 within the reference range may independently predict higher cardiovascular mortality in the general population.

Nonthyroidal Illness Syndrome in Ischaemic Stroke Patients is Associated with Increased Mortality

BACKGROUND

Results of studies on associations between triiodothyronine serum levels and mortality after acute ischemic stroke (AIS) are inconsistent. Therefore, the aim of this prospective study was to evaluate links between serum levels of thyroid axis associated hormones and all-cause mortality during 1 year after AIS.

METHODS AND RESULTS

This study involved 255 patients with AIS. Patients were divided into two groups: those who survived 1 year after their index stroke and those who not, and by quartiles of free triiodothyronine (FT3) and ΔFT3 (difference between basal FT3 and repeated FT3 on discharge) hormone serum concentrations. To assess serum levels of thyroid stimulating hormone (TSH), FT3 and free tetraiodothyronine (FT4), venous blood was taken from all included patients on admission to hospital. On discharge, blood tests were repeated for 178 (69.8%) patients. Study endpoints were overall mortality within 30, 90 and 365 days after AIS.

RESULTS

Compared with the survivals, those who died had significantly lower mean FT3, FT3/FT4 ratio in all periods and lower median TSH within 30 days. Higher FT3 serum levels versus lower, even after adjustment for included important variables, remained significant for lower odds of death within 365 days after AIS (OR=0.57; 95% CI: 0.33-0.97, p=0.04), but added insignificant additional predictive value to the NIHSS score or age. Kaplan-Meier survival curves demonstrated that the first FT3 quartile was significantly associated with increased mortality compared with all other quartiles within 365 days after AIS. With ΔFT3 quartiles no such association was found.

CONCLUSIONS

Higher FT3 levels on admission versus lower are significantly associated with lower mortality within 365 days after AIS. FT3 serum levels changes over time didn't show any association with mortality within first year.

The prognostic value of total T3 after acute cerebral infarction is age-dependent: a retrospective study on 768 patients

BACKGROUND

Serum triiodothyronine (T3) concentration was reported to be associated with the prognosis after acute ischemic stroke. The aim of this study was to evaluate the effect of age on the prognostic value of thyroid-related hormones after an acute ischemic stroke.

METHODS

This was a retrospective study involving the review of 1072 ischemic stroke patients who had been consecutively admitted to the hospital within 72 h of symptom onset. Total triiodothyronine (T3), total thyroxine (T4), free T3, free T4, and thyroid-stimulating hormone (TSH) were assessed to determine their values for predicting functional outcome at the first follow-up clinic visits, which usually occurred 2 to 4 weeks after discharge from the hospital.

RESULTS

A total of 768 patients were finally included in the study and divided into two age groups: a younger group (age < 65 years) and an older group (age ≥ 65 years). On univariate analysis, four factors-lower total T3, free T3 concentrations, higher scores on the National Institute of Health Stroke Scale (NIHSS) and the presence of atrial fibrillation-were associated with poor functional outcomes in both groups. In addition, older age, female gender, higher free T4, and lower TSH levels were also associated with poor function in the older group. On multiple logistic regression analysis, higher NIHSS scores (odds ratio [OR] =1.95; 95% confidence interval [CI], 1.66-2.30; P ≤ .001) and lower total T3 concentrations (OR = 0.06; 95% CI, 0.01-0.68; P = .024) remained independently associated with poor functional outcome in the older group. However, the independent association with poor function of lower total T3 was not confirmed in the younger group.

CONCLUSIONS

The prognostic value of low total T3 is age-associated and more meaningful in an older population.

Evidence of Aquaporin 4 Regulation by Thyroid Hormone During Mouse Brain Development and in Cultured Human Glioblastoma Multiforme Cells

Accumulating evidence indicates that thyroid function and the thyroid hormones L-thyroxine (T4) and L-triiodothyronine (T3) are important factors contributing to the improvement of various pathologies of the central nervous system, including stroke, and various types of cancer, including glioblastoma multiforme (GBM). Low levels of T3 are correlated with the poorest outcome of post-stroke brain function, as well as an increased migration and proliferation of GBM tumor cells. Thyroid hormones are known to stimulate maturation and brain development. Aquaporin 4 (AQP4) is a key factor mediating the cell swelling and edema that occurs during ischemic stroke, and plays a potential role in the migration and proliferation of GBM tumor cells. In this study, as a possible therapeutic target for GBM, we investigated the potential role of T3 in the expression of AQP4 during different stages of mouse brain development. Pregnant mice at gestational day 18, or young animals at postnatal days 27 and 57, received injection of T3 (1 μg/g) or NaOH (0.02 N vehicle). The brains of mice sacrificed on postnatal days 0, 30, and 60 were perfused with 4% paraformaldehyde and sections were prepared for immunohistochemistry of AQP4. AQP4 immunofluorescence was measured in the mouse brains and human GBM cell lines. We found that distribution of AQP4 was localized in astrocytes of the periventricular, subpial, and cerebral parenchyma. Newborn mice treated with T3 showed a significant decrease in AQP4 immunoreactivity followed by an increased expression at P30 and a subsequent stabilization of aquaporin levels in adulthood. All GBM cell lines examined exhibited significantly lower AQP4 expression than cultured astrocytes. T3 treatment significantly downregulated AQP4 in GBM-95 cells but did not influence the rate of GBM cell migration measured 24 h after treatment initiation. Collectively, our results showed that AQP4 expression is developmentally regulated by T3 in astrocytes of the cerebral cortex of newborn and young mice, and is discretely downregulated in GBM cells. These findings indicate that higher concentrations of T3 thyroid hormone would be more suitable for reducing AQP4 in GBM tumorigenic cells, thereby resulting in better outcomes regarding the reduction of brain tumor cell migration and proliferation.

Low Tri-iodothyronine Syndrome Is Associated With Cognitive Impairment in Patients With Acute Ischemic Stroke: A Prospective Cohort Study

OBJECTIVE

Low tri-iodothyronine (T3) syndrome is a predictor of poor prognosis in patients with stroke. Poststroke cognitive impairment (PSCI) is a common and important complication after stroke. The association between low T3 syndrome and PSCI is unclear. We aimed to explore the potential relationship between low T3 syndrome and PSCI in the acute phase of ischemic stroke at a 1-month follow-up visit.

METHODS

In total, 314 ischemic stroke patients were consecutively enrolled in the study and followed up at 1 month. Thyroid hormones were measured within 24 hours after admission. Cognitive function was evaluated by the Mini-Mental State Exam (MMSE) 1 month after acute ischemic stroke. Cognitive impairment was defined as an MMSE score of less than 27. Cognitive impairment severity was categorized as severe, mild, or none (MMSE score <23, 23-26, or ≥27, respectively).

RESULTS

According to the MMSE score, 182 participants (58.0%) had cognitive impairment 1 month after stroke. Patients with low T3 syndrome were more prone to have cognitive impairment than patients with normal levels of T3 (p < 0.001). After adjusting for potential confounders in our logistic model, low T3 syndrome was independently associated with PSCI (odds ratio 4.319, 95% confidence interval 1.553-12.013, p = 0.005).

CONCLUSION

Low T3 syndrome in the acute phase of ischemic stroke was associated with a higher prevalence of 1-month PSCI, independently of established risk factors.

T3 level may be a helpful marker to predict disease prognosis of acute central nervous system viral infections

AIM OF THE STUDY

Acute central nervous system viral infections are progressive and inflammatory diseases with inflammatory cells infiltrating into the central nervous system (CNS), and thyroid hormone (TH) level is associated with the oxidative and antioxidant status. Variations in oxidative stress and antioxidant status are related to the pathogenesis of inflammatory diseases. Our study aimed to investigate the possible correlation between viral infections in CNS and TH levels of thyroid stimulating hormone (TSH), free thyroxine (fT4) and free triiodothyronine (fT3).

MATERIALS AND METHODS

We measured serum concentrations of TSH, fT4, and fT3 in 206 individuals, including 59 viral meningitis (VM) patients, 60 viral encephalitis (VE) patients, and 87 healthy controls.

RESULTS

Our findings showed that VE and VM patients had lower levels of fT3 and higher levels of fT4 compared with healthy controls, whether male or female. Moreover, levels of TSH and fT3 in patients with viral infections in CNS were inversely correlated with disease prognosis measured by the Glasgow Outcome Scale.

CONCLUSIONS

Variations in TH level may represent the oxidative status and are surrogate biomarkers for disease prognosis of acute central nervous system viral infections.

Reverse triiodothyronine (rT3) attenuates ischemia-reperfusion injury

Hypothyroidism has been associated with better recovery from cerebral ischemia-reperfusion (IR) injury in humans. However, any therapeutic advantage of inducing hypothyroidism for mitigating IR injury without invoking the adverse effect of whole body hypothyroidism remains a challenge. We hypothesize that a deiodinase II (D2) inhibitor reverse triiodothyronine (rT3) may render brain specific hypometabolic state to ensue reduced damage during an acute phase of cerebral ischemia without affecting circulating thyroid hormone levels. Preclinical efficacy of rT3 as a neuroprotective agent was determined in rat model of middle cerebral artery occlusion (MCAO) induced cerebral IR and in oxygen glucose deprivation/reoxygenation (OGD/R) model in vitro. rT3 administration in rats significantly reduced neuronal injury markers, infarct size and neurological deficit upon ischemic insult. Similarly, rT3 increased cellular survival in primary cerebral neurons under OGD/R stress. Based on our results from both in vivo as well as in vitro models of ischemia reperfusion injury we propose rT3 as a novel therapeutic agent in reducing neuronal damage and improving stroke outcome.