Reverse T3 as a parameter of myocardial function impairment in heart failure

Associations of reverse triiodothyronine serum levels with anxiety, depression, and health related quality of life after experiencing acute ischemic stroke

Aim

This study intended to explore associations of reverse triiodothyronine (rT3) with emotional disturbances and health-related quality of life (HRQoL) after experiencing acute ischemic stroke (AIS).

Materials and methods

Serum samples from individuals with AIS were collected on admission to three Lithuania stroke centers and investigated for free tetraiodothyronine, free triiodothyronine (fT3), rT3, and thyroid stimulating hormone levels. At discharge, emotional disturbance was evaluated using the Hospital Depression and Anxiety Scale (HADS), and HRQoL using the EQ-5D-5L scale.

Results

Analyses included 159 individuals (59.7% male and 40.3% female; mean (SD) aged 66.4 [10.3] years), 52.83% of which showed increased rT3 levels upon admission. After adjustment for age, sex, National Institutes of Health Stroke Scale scores, previous stroke, modified Rankin Scale before AIS ≤ 2, and diabetes mellitus, multivariable linear regression revealed negative associations of rT3 with HADS total score (β = -0.163; p = 0.046) and HADS-D subscale score (β = -0.187; p = 0.019). Analyses supported a positive relationship between the fT3 ratio to rT3 with HADS-D score (β = 0.157; p = 0.046) and rT3, rT3 × fT3 product with EQ-5D index score (β = 0.157; p = 0.044 and β = 0.179; p = 0.023, respectively).

Conclusion

We found that individuals who experienced AIS and had higher levels of rT3 at hospital admission had less emotional disturbance and better HRQoL when discharged.

Myocardium of patients with dilated cardiomyopathy presents altered expression of genes involved in thyroid hormone biosynthesis

Background

The association between dilated cardiomyopathy (DCM) and low thyroid hormone (TH) levels has been previously described. In these patients abnormal thyroid function is significantly related to impaired left ventricular (LV) function and increased risk of death. Although TH was originally thought to be produced exclusively by the thyroid gland, we recently reported TH biosynthesis in the human ischemic heart.

Objectives

Based on these findings, we evaluated whether the genes required for TH production are also altered in patients with DCM.

Methods

Twenty-three LV tissue samples were obtained from patients with DCM (n = 13) undergoing heart transplantation and control donors (n = 10), and used for RNA sequencing analysis. The number of LV DCM samples was increased to 23 to determine total T4 and T3 tissue levels by ELISA.

Results

We found that all components of TH biosynthesis are expressed in human dilated heart tissue. Expression of genes encoding thyroperoxidase (–2.57-fold, P < 0.05) and dual oxidase 2 (2.64-fold, P < 0.01), the main enzymatic system of TH production, was significantly altered in patients with DCM and significantly associated with LV remodeling parameters. Thyroxine (T4) cardiac tissue levels were significantly increased (P < 0.01), whilst triiodothyronine (T3) levels were significantly diminished (P < 0.05) in the patients.

Conclusions

Expression of TH biosynthesis machinery in the heart and total tissue levels of T4 and T3, are altered in patients with DCM. Given the relevance of TH in cardiac pathology, our results provide a basis for new gene-based therapeutic strategies for treating DCM.

Thyroxine increases Serca2 and Ryr2 gene expression in heart failure rats with euthyroid sick syndrome

OBJECTIVE

The current study was aimed at analyzing sarcoplasmic reticulum Ca2+ ATPase (Serca2) and ryanodine receptor type 2 (Ryr2) gene expression in rats subjected to surgery that induced HF and were subsequently treated with T4 using physiological doses.

MATERIALS AND METHODS

HF was induced in 18 male Wistar rats by clipping the ascending thoracic aorta to generate aortic stenosis (HFS group), while the control group (9-sham) underwent thoracotomy. After 21 weeks, the HFS group was subdivided into two subgroups. One group (9 Wistar rats) with HF received 1.0 µg of T4/100 g of body weight for five consecutive days (HFS/T4); the other group (9 Wistar rats) received isotonic saline solution (HFS/S). The animals were sacrificed after this treatment and examined for signs of HF. Samples from the left ventricles of these animals were analyzed by RT-qPCR for the expression of Serca2 and Ryr2 genes.

RESULTS

Rats with HF developed euthyroid sick syndrome (ESS) and treatment with T4 restored the T3 values to the Sham level and increased Serca2 and Ryr2 gene expression, thereby demonstrating a possible benefit of T4 treatment for heart function in ESS associated with HF.

CONCLUSION

The T4 treatment can potentially normalize the levels of T3 as well elevated Serca2 and Ryr2 gene expression in the myocardium in heart failure rats with euthyroid sick syndrome.