Relationships between basal hypothalamic-pituitary-thyroid-axis activity and plasma haptoglobin levels in depression

Expression levels of interferon-ɣ and type 2 deiodinase in patients diagnosed with recurrent depressive disorders

BACKGROUND

Thyroid hormones (TH) are involved in modulation of the immune system and inflammation. TH dysregulation is associated with depressive disorders. The iodothyronine deiodinases (DIOs), the key enzymes for TH synthesis, can be affected and induced by pro-inflammatory cytokines. We aimed to investigate the levels of and correlation between type 2 DIO (DIO2) and interferon-gamma (IFN-ɣ) in patients with recurrent depressive disorders (rDD).

METHODS

Data from 91 rDD patients and 105 healthy controls were analyzed. The diagnoses are based on the ICD-10 criteria (F33.0-F33.8). Expression levels of DIO2 and IFN-ɣ were estimated using the method based on the polymerase chain reaction and the enzyme-linked immunosorbent assay (ELISA).

RESULTS

The DIO2 expression on mRNA/protein levels in rDD patients (both female and males) was reduced as compared with the control subjects. No correlation between DIO2 and IFN-ɣ expression was observed.

CONCLUSION

This is the first study to reveal that one may cautiously suggest that DIO2 may be involved in the development and/or progression of rDD. The mechanisms of TH regulation on depression, however, need further investigation.

Polymorphisms of iodothyronine deiodinases (DIO1, DIO3) genes are not associated with recurrent depressive disorder

BACKGROUND

Depressive disorder is characterized by disturbances in the hypothalamic-pituitary-thyroid (HPT) axis and in the metabolism of thyroid hormones (TH). The evidence for changes in TH levels is observed in human sera and cerebrospinal fluid as well as in animal model studies. Iodothyronine deiodinases (DIOs) type 1, 2 and 3 (DIO1, DIO2, DIO3) are important enzymes for the synthesis and determination of TH concentration. This study aims to examine the link between recurrent depressive disorders (rDD) and two functionally known polymorphisms DIO1a-C/T (rs11206244) and DIO1b-A/G (rs12095080) within the DIO1 gene encoding DIO1 and two polymorphisms DIO3-C/T (rs17716499), DIO3-A/C (rs7150269) within the DIO3 gene encoding DIO3.

METHODS

Both variants were genotyped in 254 rDD patients and 197 healthy subjects using polymerase chain reaction. Basic methods and statistical analyses were used to estimate genetic variants in the risk of the disease.

RESULTS

No significant associations were found between the polymorphisms examined here and rDD. There were no significant associations between genotypes distribution and demographic/medical variables. Odds ratios (ORdis) and corresponding 95% confidence interval (95% CI) were calculated, for example: for CC genotype of DIO1a C/T (ORdis=0.86, 95% CI: 0.59, 1.25).

CONCLUSION

Functional variants within the DIO1 gene, which affect TH levels and polymorphisms in DIO3, are not confirmed to be associated with rDD. Nevertheless, considering previous data which indicate that the DIO1 gene is related to the depression, further studies on a larger sample size are recommended.

Serum haptoglobin levels in patients with melancholic and nonmelancholic major depression

BACKGROUND

Major depression (MD) is accompanied by systemic immune activation or an inflammatory response with the involvement of phagocytic cells, T cell activation, B cell proliferation, and an acute phase response with increased levels of positive and decreased levels of negative acute-phase proteins. In this study, we aimed to determine any differences in serum haptoglobin (Hp) concentrations among patients with melancholic and nonmelancholic MD and the healthy controls.

METHODS

This study involved 125 male patients who were admitted to the Department of Psychiatry, Gulhane Military Medical Academy (GMMA), in Ankara, Turkey. They were diagnosed with MD according to the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) and agreed to participate in the study. The melancholic group consisted of 37 patients and the nonmelancholic group had 45 patients. A healthy control group of 40 subjects was selected from the staff of GMMA. These subjects had not had any lifetime psychiatric diagnosis or psychiatric treatment in their medical histories. Peripheral venous blood samples were obtained from the patients and the control group for a complete blood count, routine biochemistry, and the detection of serum Hp levels.

RESULTS

There was no statistically significant difference among the melancholic MD, the nonmelancholic MD, and the healthy control groups in terms of age, level of education, and gender. Serum Hp concentrations are significantly higher in melancholic patients as compared with non-melancholic depressed patients and controls. However, there was no statistically significant difference between the nonmelancholic MD and the control group in terms of Hp concentrations.

CONCLUSION

The results of this study are important in terms of showing different serum Hp concentrations in patients with melancholic and nonmelancholic MD.

Peripheral thyroid dysfunction in depression

The involvement of the thyroid gland and thyroid hormones is generally believed to be important in the aetiopathogenesis of major depression. Major support comes from studies in which alterations in components of the hypothalamic-pituitary-thyroid (HPT) axis have been documented in patients with primary depression. However, screening thyroid tests are often routine and add little to the diagnostic evaluation. Overt thyroid disease is rare among depressed inpatients. The finding that depression often co-exists with autoimmune subclinical thyroiditis suggests that depression may cause alterations in the immune system, or that in fact it could be an autoimmune disorder itself. The outcome of treatment and the course of depression may be related to thyroid status as well. Augmentation of antidepressant therapy with the co-administration of thyroid hormones (mainly T3) is a well-documented treatment option for refractory depressed patients. Review of the literature suggests that there are no conclusive data on the role of thyroid function in depression. It is clear that depression is not characterised by an overt thyroid dysfunction, but it is also clear that a subgroup of depressed patients may manifest subtle thyroid abnormalities, or an activation of an autoimmune process. There is a strong possibility that the presence of a subtle thyroid dysfunction is a negative prognostic factor for depression and may demand specific therapeutic intervention.