Genetic variation in the myeloperoxidase gene and cognitive impairment in multiple sclerosis

Myeloperoxidase gene expression and cognitive functions in depression

PURPOSE

Most researchers agree that there are multiple factors influencing the development of recurrent depressive disorder (rDD). Previous studies have found that myeloperoxidase (MPO) may be a key inflammatory enzyme involved in this disorder. The purpose of this study was to determine the mRNA and protein levels of MPO in patients with rDD and to define the relationship between serum MPO levels and cognitive performance.

MATERIAL/METHODS

The study comprised 236 subjects: patients with rDD (n=131) and healthy subjects (n=105, HS). Assessment of cognitive function was based on performance on the Trail Making Test, the Stroop Test, the Verbal Fluency Test (VFT) and the Auditory-Verbal Learning Test (AVLT).

RESULTS

MPO gene expression at mRNA level and at protein level was significantly higher in the rDD group when compared to the HS (p<0.01). There were no significant correlations for each group separately, but in the entire group, statistically significant correlations occurred between both mRNA and protein levels and following test: TMT part A and part B (positive correlations), part RCNb and part NCWd of the Stroop Test (positive correlation), the Verbal Fluency Test (negative correlation) and the AVLT (negative correlation).

CONCLUSIONS

Our study provides evidence that the MPO enzyme coding gene and MPO expression are important for the regulation of cognitive functioning.

Impact of oxidative/nitrosative stress and inflammation on cognitive functions in patients with recurrent depressive disorders

Data show that up to 38.2% of the European population have a mental disorder and that recurrent depressive disorder (rDD) is among the most commonly diagnosed disabling diseases. Over the last few years, neurocognitive impairments in rDD have become a new research front focusing on the role of cognitive decline during the course of rDD and in relation to its clinical presentation and prognosis. Both immune-inflammatory and oxidative and nitrosative stress (O&NS) processes potentially play a role in development of cognitive dysfunction in rDD. New evidence shows that chronic inflammatory and O&NS reactions occur in the brains of patients with neurodegenerative disorders and those with rDD. This narrative review presents the current state of knowledge on the possible impact of selected inflammatory and O&NS enzymes on cognitive functioning in patients with rDD. We focus on manganese superoxide dismutase (MnSOD), inducible nitric oxide synthase (iNOS), and myeloperoxidase (MPO).

Functional polymorphism of the myeloperoxidase gene (G-463A) in depressive patients

Gałecki P, Florkowski A, Bobińska K, Śmigielski J, Bieńkiewicz M, Szemraj J. Functional polymorphism of the myeloperoxidase gene (G-463A) in depressive patients.

OBJECTIVE

Myeloperoxidase (MPO) is an enzyme involved in the production of hypochloric acid as well as other reactive oxygen species. This enzyme plays a significant role in inflammatory processes. In view of the observed associations between depression and such inflammatory processes, as well as of the reports that confirm the presence of oxidative stress in depression, this study was designed to assess the correlation, if any, between the single nucleotide polymorphism G-463A of the MPO gene and the risk of recurrent depressive disorders (DD).

METHODS

The study was carried out in a group of 149 patients with recurrent DD and 149 healthy control subjects. Genotyping was performed by PCR/restriction fragment length polymorphism.

RESULTS

A comparison between healthy controls and depressive patients showed a statistically significant difference in genotype distribution and allele frequency in the studied groups. Genotype distribution and allele frequency did not correlate with clinical variables of the patients.

CONCLUSION

The obtained results of the study allow us to draw a cautious conclusion about the role of the analysed G-463A MPO polymorphism in recurrent DD development, which, however, requires eventual confirmation in further studies.