Resting-state fMRI reveals changes within the anxiety and social avoidance circuitry of the brain in mice with psoriasis-like skin lesions

Differential regulation of pruritic sensation and emotion by cannabinoid type 1 receptors on mPFC glutamatergic and GABAergic neurons

Itch causes a strong urge to scratch and induces negative emotions, such as aversion and anxiety. Antihistamine medications are key in the clinical management of pruritus, but their therapeutic efficacy in controlling moderate and severe itching remains limited. The neural circuits in the brain that process itching and itch-induced aversion and anxiety remain unclear so far. Human brain imaging suggests that the medial prefrontal cortex (mPFC) is involved in processing the emotional and motivational components of itching. In this study, we investigated the mechanisms by which glutamatergic and GABAergic neurons in mPFC differentially regulated pruritic sensation and emotion through cannabinoid type 1 receptors (CB1Rs). Chloroquinoline (CQ)-induced acute and calcipotriol (MC903)-induced chronic itch models were established. Fiberoptic calcium imaging was used to detect the activity of the two types of neurons in response to itching. The CB1R antagonist AM251 (0.5 mg in 200 nL) was microinjected into the mPFC through the implanted cannula. We showed that chemogenetic activation of glutamatergic neurons and inhibition of GABAergic neurons in the mPFC reduced scratching and chronic itch-induced anxiety. GABAergic, but not glutamatergic, neurons were involved in acute itch-induced aversion. CB1Rs on glutamatergic and GABAergic neurons modulated chronic itch-induced scratching and anxiety in divergent manners. However, CB1Rs did not affect acute itch-induced scratching. CB1Rs on GABAergic, but not glutamatergic, neurons regulated acute itch-induced aversion. These results may guide the development of therapeutic strategies targeting CB1Rs to treat itch-induced sensory and emotional responses.

Molecular Link Between Psoriasis and Depression-Update on Pathophysiology

Psoriasis disease is a chronic, systemic condition. Various epidemiological studies have indicated a connection between psoriasis and psychiatric diseases. It is obvious that easily visible psoriatic skin lesions cause stigmatization of patients and impact noticeably their life quality, increasing the risk of anxiety and depressive disorders. More and more attention is recently being paid to the common pathogenesis of psoriasis and depression. The underlying cause of psoriasis is chronic inflammation, and depression is also increasingly recognized as a result of neuroinflammation. Therefore, the complexity of the processes underlying both disease entities implies the need to observe psoriatic patients in terms of possible comorbidities, such as mental disorders, regardless of the severity of skin lesions and social stigmatization. This study aims to present an update on the common pathophysiology of both diseases.

MRI-based neuroimaging alterations in immune-related skin diseases: a comprehensive review

The skin, as the largest organ in the human body, serves as the primary physical barrier and plays a crucial role in the immune defense process. Immune-related skin diseases encompass a spectrum of complex dermatological conditions characterized by aberrant immune responses, including the production of autoantibodies and dysregulation of inflammatory mediators. Growing evidence suggest a heightened prevalence of comorbid neuropsychiatric disorders among patients with immune-related skin diseases, indicative of potential shared pathogenesis. In recent years, the brain connectome, delineating the intricate network of neural connections, has gained prominence in elucidating various neurological and psychiatric conditions. Researchers have begun to investigate whether alterations in brain connectivity occur in patients with immune-related skin diseases, thereby exploring the connectome perspective in understanding the pathogenesis of these diseases. This review aims to synthesize and analyze recent neuroimaging studies about immune-related skin diseases, including systemic lupus erythematosus, psoriasis, chronic spontaneous urticaria, and atopic dermatitis. We mainly discussed the connectome studies related to these diseases and summarized the underlying mechanisms associated with their clinical manifestations, progression, and treatment. Then from our perspectives, we believe that interdisciplinary collaborations encompassing fields such as neurology, psychiatry, dermatology, and neuroimaging will be instrumental in advancing our understanding of immune-related skin diseases. Furthermore, multi-omics approaches will enable a comprehensive exploration of the molecular mechanisms underlying these neural changes, facilitating the identification of novel diagnostic biomarkers and therapeutic targets.

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.