Inhibitory effect of antidepressant drugs on contact hypersensitivity reaction is connected with their suppressive effect on NKT and CD8(+) T cells but not on TCR delta T cells

Immune-Regulatory and Molecular Effects of Antidepressants on the Inflamed Human Keratinocyte HaCaT Cell Line

Allergic contact dermatitis (ACD) is a T cell-mediated type of skin inflammation resulting from contact hypersensitivity (CHS) to antigens. There is strong comorbidity between ACD and major depression. Keratinocytes release immunomodulatory mediators including pro-inflammatory cytokines and chemokines, which modulate skin inflammation and are crucial cell type for the development of CHS. Our previous studies showed that fluoxetine and desipramine were effective in suppressing CHS in different mouse strains. However, the immune and molecular mechanisms underlying this effect remain to be explored. The aim of the current study was to determine the immune and molecular mechanisms of action of antidepressant drugs engaged in the inhibition of CHS response in the stimulated keratinocyte HaCaT cell line. The results show that LPS, TNF-α/IFN-γ, and DNFB stimulate HaCaT cells to produce large amounts of pro-inflammatory factors including IL-1β, IL-6, CCL2, and CXCL8. HaCaT stimulation was associated with increased expression of ICAM-1, a cell adhesion molecule, and decreased expression of E-cadherin. Imipramine, desipramine, and fluoxetine suppress the production of IL-1β, CCL2, as well as the expression of ICAM-1. LPS and TNF-α/IFN-γ activate p-38 kinase, but antidepressants do not regulate this pathway. LPS decreases E-cadherin protein expression and fluoxetine normalizes these effects. In summary, the antidepressant drugs examined in this study attenuate the stimulated secretion of pro-inflammatory cytokines, chemokines, and modulate adhesion molecule expression by the HaCaT cell line. Therefore, antidepressants may have some clinical efficacy in patients with ACD and patients with comorbid depression and contact allergy.

An integrative network analysis framework for identifying molecular functions in complex disorders examining major depressive disorder as a test case

In addition to the psychological depressive phenotype, major depressive disorder (MDD) patients are also associated with underlying immune dysregulation that correlates with metabolic syndrome prevalent in depressive patients. A robust integrative analysis of biological pathways underlying the dysregulated neural connectivity and systemic inflammatory response will provide implications in the development of effective strategies for the diagnosis, management and the alleviation of associated comorbidities. In the current study, focusing on MDD, we explored an integrative network analysis methodology to analyze transcriptomic data combined with the meta-analysis of biomarker data available throughout public databases and published scientific peer-reviewed articles. Detailed gene set enrichment analysis and complex protein–protein, gene regulatory and biochemical pathway analysis has been undertaken to identify the functional significance and potential biomarker utility of differentially regulated genes, proteins and metabolite markers. This integrative analysis method provides insights into the molecular mechanisms along with key glycosylation dysregulation underlying altered neutrophil-platelet activation and dysregulated neuronal survival maintenance and synaptic functioning. Highlighting the significant gap that exists in the current literature, the network analysis framework proposed reduces the impact of data gaps and permits the identification of key molecular signatures underlying complex disorders with multiple etiologies such as within MDD and presents multiple treatment options to address their molecular dysfunction.

Selegiline and clomipramine effects on lymphocyte subsets, regulatory T cells and sheep red blood cell (SRBC)-induced humoral immune response after in vivo administration in mice

We aimed at investigating the influence of clomipramine and selegiline administered in vivo in mice on lymphocyte subsets in lymphoid organs and SRBC-induced humoral immune response. Balb/c mice were given 7 or 14 oral doses (1 mg/kg) of selegiline or clomipramine. Lymphocyte B and T subsets and splenic regulatory T cell (Treg) subset were determined in non-immunized mice 24 and 72 h after the last dose of the drugs. Some mice treated with 7 doses were immunized with sheep red blood cells (SRBC) 2 h after the last dose, and their number of antibody forming cells, haemagglutinin titers and splenocyte subsets were determined. An increase in T lymphocytes and a decrease in B cells were visible in peripheral lymphoid organs, especially after 14 doses of selegiline or clomipramine in non-immunized mice, as well as in spleens of SRBC-immunized mice. The most pronounced change was a decrease in CD4⁺/CD8⁺ ratio resulting mainly from an increase in CD8⁺ subset after seven doses of the drugs in the non-immunized mice. However, it was of a transient nature, as it disappeared after 14 doses of the drugs. The tested drugs only slightly affected thymocyte maturation and did not alter Treg subset. Selegiline and clomipramine transiently stimulated IgG production in SRBC-immunized mice. Both selegiline and clomipramine administered in vivo modulated lymphocyte subsets. This immunomodulatory effect depended on the drug as well as duration of administration.

The role of invariant T cells in inflammation of the skin and airways

Invariant and semi-invariant T cells are emerging as important regulators of host environment interactions at barrier tissues such as the airway and skin. In contrast to conventional T cells, invariant natural killer T (iNKT) cells and mucosal associated invariant T (MAIT) cells express T cell receptors of very limited diversity. iNKT and MAIT cells recognise antigens presented by the MHC class 1-like monomorphic molecules CD1d and MR1, respectively. Both iNKT cells and MAIT cells have been identified in the skin and airways and can rapidly produce cytokines after activation. Numerous studies have implicated iNKT cells in the pathology of both skin and airway disease, but conflicting evidence in human disease means that more studies are necessary to resolve the exact roles of iNKT in inflammation. The functions of MAIT cells in skin and lung inflammation are even less well defined. We herein describe the current literature on iNKT and MAIT cells in allergic and non-allergic skin diseases (dermatitis and psoriasis) and airway diseases (asthma, chronic obstructive pulmonary disease, rhinitis, and chronic rhinosinusitis).

Resilience and immunity

Resilience is the process that allows individuals to adapt to adverse conditions and recover from them. This process is favored by individual qualities that have been amply studied in the field of stress such as personal control, positive affect, optimism, and social support. Biopsychosocial studies on the individual qualities that promote resilience show that these factors help protect against the deleterious influences of stressors on physiology in general and immunity in particular. The reverse is also true as there is evidence that immune processes influence resilience. Most of the data supporting this relationship comes from animal studies on individual differences in the ability to resist situations of chronic stress. These data build on the knowledge that has accumulated on the influence of immune factors on brain and behavior in both animal and human studies. In general, resilient individuals have a different immunophenotype from that of stress susceptible individuals. It is possible to render susceptible individuals resilient and vice versa by changing their inflammatory phenotype. The adaptive immune phenotype also influences the ability to recover from inflammation-induced symptoms. The modulation of these bidirectional relationships between resilience and immunity by the gut microbiota opens the possibility to influence them by probiotics and prebiotics. However, more focused studies on the reciprocal relationship between resilience and immunity will be necessary before this can be put into practice.

Inflammatory Mediators in Mood Disorders: Therapeutic Opportunities

Mood disorders such as depression are among the most prevalent psychiatric disorders in the United States, but they are inadequately treated in a substantial proportion of patients. Accordingly, neuropsychiatric research has pivoted from investigation of monoaminergic mechanisms to exploration of novel mediators, including the role of inflammatory processes. Subsets of mood disorder patients exhibit immune-related abnormalities, including elevated levels of proinflammatory cytokines, monocytes, and neutrophils in the peripheral circulation; dysregulation of neuroglia and blood-brain barrier function; and disruption of gut microbiota. The field of psychoneuroimmunology is one of great therapeutic opportunity, yielding experimental therapeutics for mood disorders, such as peripheral cytokine targeting antibodies, microglia and astrocyte targeting therapies, and probiotic treatments for gut dysbiosis, and producing findings that identify therapeutic targets for future development.

The role of macrophages in anti-inflammatory activity of antidepressant drugs

Depression is a common disease influencing patients' quality of life, whose etiology involves complex interactions of environmental, genetic and immunological factors. The latter factors include proinflammatory activation of monocytes and macrophages and increased serum levels of proinflammatory cytokines, altogether formulated as the "macrophage theory of depression". Our current review summarizes the impact of the most commonly used antidepressant drugs on the immune response with special emphasis on the role of macrophages in the clinically observed effects. The anti-inflammatory action of antidepressants mainly results from their direct interaction with immune cells and from changes in the concentration and the relations of neurotransmitters sensed by these cells. The summarized data revealed that Mφs are one of the leading cell populations involved in drug-mediated immune effects that can be observed both in subjects with depression as well as in individuals not suffering from depression. Thus, currently reviewed immunomodulatory effects of the experimental use of different antidepressant drugs suggest the possibility of utilizing them in complex therapeutic strategies dedicated to various inflammatory and immune-mediated diseases. It is worth noting that an excessive inflammatory reaction is also associated with the pathogenesis of various cardiovascular, metabolic and neuro-endocrine diseases. Thus, the inclusion of antidepressants in the complex therapy of these disorders may have beneficial effects through the enhancement of the mood of the patient and alleviation of chronic inflammation. On the other hand, presented data suggest that the influence of chronically used antidepressants on anti-microbial and anti-tumor immunity could also be taken into consideration.