Transient anxiety-and depression-like behaviors are linked to the depletion of Foxp3-expressing cells via inflammasome in the brain

Conductive polyphenol microneedles coupled with electroacupuncture to accelerate wound healing and alleviate depressive-like behaviors in diabetes

Inflammation and depression are serious complications of diabetes that interact to form a feedback loop and may hinder diabetic wound healing. They share a common pathophysiological basis of abnormal interactions between diabetic wounds and the brain. Here, we propose a strategy combining electroacupuncture (EA) stimulation of the Dazhui acupoint (GV14) with polyphenol-mediated conductive hydrogel microneedles to promote diabetic wound healing and alleviate depression through local wound-brain interactions. The conductive microneedles comprised methacrylated gelatin, dopamine (DA), DA-modified poly(3,4-ethylenedioxythiophene), and Lycium barbarum polysaccharide. EA at GV14 activated the vagus-adrenal axis to inhibit systemic inflammation while DA coupled electrical signals for long-term inhibition of local wound inflammation. EA at GV14 was also found to elevate 5-hydroxytryptamine levels in rats with diabetic wounds, consequently mitigating depressive-like behaviors. Additionally, the polyphenol-mediated conductive hydrogel microneedles, and coupled with EA stimulation promoted healing of wound tissue and peripheral nerves. This strategy regulated both local and systemic inflammation while alleviating depressive-like behaviors in diabetic rats, providing a new clinical perspective for the treatment of diabetes-related and emotional disorders.

The role of enteric nervous system and GDNF in depression: Conversation between the brain and the gut

Depression is a debilitating mental disorder that causes a persistent feeling of sadness and loss of interest. Approximately 280 million individuals worldwide suffer from depression by 2023. Despite the heavy medical and social burden imposed by depression, pathophysiology remains incompletely understood. Emerging evidence indicates various bidirectional interplay enable communication between the gut and brain. These interplays provide a link between intestinal and central nervous system as well as feedback from cortical and sensory centers to enteric activities, which also influences physiology and behavior in depression. This review aims to overview the significant role of the enteric nervous system (ENS) in the pathophysiology of depression and gut-brain axis's contribution to depressive disorders. Additionally, we explore the alterations in enteric glia cells (EGCs) and glial cell line-derived neurotrophic factor (GDNF) in depression and their involvement in neuronal support, intestinal homeostasis maintains and immune response activation. Modulating ENS function, EGCs and GDNF level could serve as novel strategies for future antidepressant therapy.

From bite to brain: Neuro-immune interactions in food allergy

Immunoglobulin E (IgE)-mediated food allergies are reported to affect around 3.5% of children and 2.4% of adults, with symptoms varying in range and severity. While being the gold standard for diagnosis, oral food challenges are burdensome, and diagnostic tools based on specific IgE can be flawed. Furthering our understanding of the mechanisms behind food allergy onset, severity and persistence could help reveal immune profiles associated with the disease, to ultimately aid in diagnosis. Alterations to cytokine levels and immune cell ratios have been identified, though further research is needed to fully capture the heterogenous nature of food allergy. Moreover, the existence of such immune alterations also raises the question of potential wider systemic effects. For example, recent research has emphasised the existence and impact of neuro-immune interactions and implicated behavioural and neurological changes associated with food allergy. This review will provide an overview of such food allergy-driven neuro-immune interactions, with the aim of emphasising the importance of furthering our understanding of the immune mechanisms underlying IgE-mediated food allergy.

Regulatory T cells administration reduces anxiety-like behavior in mice submitted to chronic restraint stress

Background

Major depression disorder (MDD) and anxiety are common mental disorders that significantly affect the quality of life of those who suffer from them, altering the person's normal functioning. From the biological perspective, the most classical hypothesis explaining their occurrence relies on neurotransmission and hippocampal excitability alterations. However, around 30% of MDD patients do not respond to medication targeting these processes. Over the last decade, the involvement of inflammatory responses in depression and anxiety pathogenesis has been strongly acknowledged, opening the possibility of tackling these disorders from an immunological point of view. In this context, regulatory T cells (Treg cells), which naturally maintain immune homeostasis by suppressing inflammation could be promising candidates for their therapeutic use in mental disorders.

Methods

To test this hypothesis, C57BL/6 adult male mice were submitted to classical stress protocols to induce depressive and anxiety-like behavior; chronic restriction stress (CRS), and chronic unpredictable stress (CUS). Some of the stressed mice received a single adoptive transfer of Treg cells during stress protocols. Mouse behavior was analyzed through the open field (OFT) and forced swim test (FST). Blood and spleen samples were collected for T cell analysis using cell cytometry, while brains were collected to study changes in microglia by immunohistochemistry.

Results

Mice submitted to CRS and CUS develop anxiety and depressive-like behavior, and only CRS mice exhibit lower frequencies of circulating Treg cells. Adoptive transfer of Treg cells decreased anxiety-like behavior in the OFT only in CRS model, but not depressive behavior in FST in neither of the two models. In CRS mice, Treg cells administration lowered the number of microglia in the hippocampus, which increased due this stress paradigm, and restored its arborization. However, in CUS mice, Treg cells administration increased microglia number with no significant effect on their arborization.

Conclusion

Our results for effector CD4+ T cells in the spleen and microglia number and morphology in the hippocampus add new evidence in favor of the participation of inflammatory responses in the development of depressive and anxiety-like behavior and suggest that the modulation of key immune cells such as Treg cells, could have beneficial effects on these disorders.

CD4+ T-cell subsets are associated with chronic stress effects in newly diagnosed anxiety disorders

Aim

Prior research has indicated a connection between CD4+ T cells and the development of anxiety, but the specific CD4+ T cell subsets linked to anxiety disorders remain uncertain. Our study seeks to investigate the relationship between distinct CD4+ T cell subsets and anxiety, as well as to explore whether CD4+ T cell subsets mediate the effect of chronic psychological stress on anxiety.

Methods

56 eligible matched participants were recruited in Peking Union Medical College Hospital. The diagnosis was made based on DSM-5 diagnostic criteria. The severity of anxiety and depression symptoms was assessed using the Hamilton Anxiety Rating Scale and Hamilton Depression Rating Scale, respectively. The Life Events Scale (LES) evaluated the chronic stress level. CD4+ T cell subsets were characterized using multiparametric flow cytometry. To assess the impact of CD4+ T cells on the effect of chronic psychological stress on anxiety, Partial Least Squares Structural Equation Modeling (PLS-SEM) analysis was employed.

Results

We discovered fifteen notably distinct CD4+ T-cell subsets in anxiety disorder patients compared to healthy controls. Multiple linear regression analysis unveiled an association between anxiety severity and CD27+CD45RA- Th cells, CD27+CD28+ Tregs, and the total Life Events Scale (LES) score. The PLS-SEM analysis demonstrated that CD4+ T cell subsets and LES could explain 80.2% of the variance in anxiety. Furthermore, it was observed that CD27+CD28+ Th/Treg cells acted as inverse mediators of the effects of LES on anxiety (P = 0.031).

Conclusions

Drug naïve anxiety disorder patients exhibited significant alterations in numerous CD4+ T-cell subsets. Specifically, the memory subset of CD27+CD45RA- Th cells and the naïve subset of CD27+CD28+ Treg cells were found to be independent factors associated with the severity of anxiety. Additionally, the CD27+CD28+ Th and Treg cell subsets played a significant mediating role in the influence of long-term psychological stress on anxiety.

T cell-mediated skin-brain axis: Bridging the gap between psoriasis and psychiatric comorbidities

Psoriasis, a chronic inflammatory skin condition, is often accompanied by psychiatric comorbidities such as anxiety, depression, suicidal ideation, and other mental disorders. Psychological disorders may also play a role in the development and progression of psoriasis. The intricate interplay between the skin diseases and the psychiatric comorbidities is mediated by the 'skin-brain axis'. Understanding the mechanisms underlying psoriasis and psychiatric comorbidities can help improve the efficacy of treatment by breaking the vicious cycle of diseases. T cells and related cytokines play a key role in the pathogenesis of psoriasis and psychiatric diseases, and are crucial components of the 'skin-brain axis'. Apart from damaging the blood-brain barrier (BBB) directly, T cells and secreted cytokines could interact with the hypothalamic-pituitary-adrenal axis (HPA axis) and the sympathetic nervous system (SNS) to exacerbate skin diseases or mental disorders. However, few reviews have systematically summarized the roles and mechanisms of T cells in the interaction between psoriasis and psychiatric comorbidities. In this review, we discussed several key T cells and their roles in the 'skin-brain axis', with a focus on the mechanisms underlying the interplay between psoriasis and mental commodities, to provide data that might help develop effective strategies for the treatment of both psoriasis and psychiatric comorbidities.