Interleukin 17 and Treg – a common pathomechanism and a new target of therapy in rheumatic diseases and depression

摘要

Depression is one of the most common mental disorders. It affects 10–15% of the population [1]. Depression is closely linked with deterioration of the quality of life of patients and has a?negative impact on the course of coexisting diseases. in Europe, 4.5% of the population suffer from rheumatic diseases such as rheumatoid arthritis, systemic lupus erythematosus, systemic sclerosis, psoriatic arthritis, and ankylosing spondylitis. The percentage of people in this group suffering from depression is elevated threefold – to approximately 50% [2]. Therefore, it is extremely important to learn about the interdependence of these diseases. Research conducted in the last decade shows that the inflammatory process, which is the basis for the development of both diseases, is a?significant aspect of this co-morbidity. In the course of depression, it reduces the availability of tryptophan for serotonin production. This leads to intensification of neurodegenerative processes [3]. A?proper cognitive and emotional response requires balanced cooperation of the limbic system structures with the amygdala and the hippocampus as well as the prefrontal cortex. This area has a?regulatory role. An imbalance in the presence of the inflammatory process causes hyperactivity of limbic structures accompanied by decreased inhibitory capacity of the prefrontal cortex. It is manifested among others in the form of depression. Patients show persistent overreaction to negative stimuli [4]. The immune and affective responses are inseparable aspects of the response to changes in the body (biological or psychological stressors). The immune system has been a?coordinating and integrating system since the very beginning. Its nature and significance in the occurrence of depressive disorders are confirmed by its systemic omnipresence. Additionally, both systems have the same critical developmental moments [5]. They can have a?protective role or amplify harmful reactions, such as an increase in interleukin 6 (IL-6) or anxiety, which are a?source of proinflammatory activity of the immune system. This is possible by deregulating the hypothalamic–pituitary–adrenal axis (HPA) [6]. The process of differentiation of CD4+ lymphocytes is important in the development of the immune system. It enables conversion of one type of cells into another type but is also flexible because the transformations can be reversible. The phenotypic and functional boundaries between their...