Connections between nerve endings and epidermal cells: are they synapses?

Abstract: Based on electron microscopy and confocal scanning microscopy, contacts between sensory axons and the cells of the epidermis have been described: with keratinocytes, Langerhans cells, melanocytes and Merkel cells. We would like to initiate a debate on this question: “Are neuro‐epidermal connections synapses?”. Anatomically, neuro‐epidermal junctions can be considered as synapses in our opinion. If neuro‐epidermal junctions are synapses, they probably belong to the family of en passant synapses, with nerve endings passing along epidermal cells and occasionally connecting to them. In conclusion, we suggest that neuro‐epidermal junctions could be considered as true synapses, but this does not exclude non synaptic interactions.     

Functional HIV CXCR4 coreceptor on human epithelial Langerhans cells and infection by HIV strain X4

HIV can cross the intact epithelium of genital mucosae via Langerhans cells. Fresh Langerhans cells are known to express CD4 and CCR5. The presence of CXCR4 on the surface of cultured but not freshly isolated Langerhans cells has been described. In the present study, we demonstrate that CXCR4 was expressed by fresh Langerhans cells isolated and purified from epidermis. However, the percentage of Langerhans cells expressing CXCR4 or CCR5 increased during maturation of the cells in culture, especially in the presence of exogenous granulocyte-macrophage colony-stimulating factor. To determine whether CXCR4 was functional, freshly isolated Langerhans cells were infected with HIV LAI, a T-cell-tropic strain, and p24 protein production was measured in culture supernatants. p24 production was observed when infected Langerhans cells were cocultured with SupT1 cells. However, the presence of HIV provirus DNA was evidenced within the infected Langerhans cells by nested PCR. Ultrastructural studies confirmed the formation of syncytia when Langerhans cells were cocultured with SupT1 cells. Preincubation of Langerhans cells with azidothymidine or SDF-1-alpha, a natural ligand for CXCR4, prevented infection. These data demonstrated that CXCR4 is present on the surface of Langerhans cells freshly isolated from human skin epidermis and that this expression is functional.     

Stress and seborrheic dermatitis

BACKGROUND: It is widely accepted that episodes of seborrheic dermatitis are frequently induced by stress, as stated in all general reviews of the subject. However, there have been no studies to confirm this view. PATIENTS AND METHODS: This prospective study was performed in two phases. An initial questionnaire collected information on patients' identity, somatic and psychiatric history and seborrheic dermatitis characteristics. Information on triggering episodes was sought by means of an open question and patients were then asked if they had experienced stress during the week or month prior to the active episode. A second questionnaire containing the same questions (except for history) was completed four months later. The two questionnaires contained psychopathological evaluation scales designed to detect symptoms of anxiety and depression among patients (HAD: Hospital Anxiety and Depression scale; Beck; STAI: State-Trait Anxiety Inventory) and determine their perceived stress (PSS: Perceived Stress Scale by Cohen and Williamson). RESULTS: Eighty-two patients (36 women and 46 men) were included in the study. 82% of patients presented involvement of scalp, 33% of the face, 19% of the chest and 13% of other sites (ears, skinfolds). Patients themselves identified stress as the main triggering factor, whether for episodes in general, for the first episode or for the current episode. A stressful event was in fact found in the majority of cases. The fact that stress was recognised as a triggering factor for episodes was not associated with a higher depression score (HAD or Beck) but was associated with a higher anxiety score (STAI). The psychological effects of the disease were pronounced in 11% of patients, moderate in 20%, mild in 35%, and nil in 25%, with 9% of patients stating no opinion. Patients with facial involvement were more depressed in terms of Beck Depression Index score. Two characteristics noted at inclusion were predictive for the onset of at least one further episode or persistence of an ongoing episode four months later: patients' designation of stress as the cause of the previous episode, and STAI score. DISCUSSION: This study confirms that seborrheic dermatitis is often preceded by a stressful event and that stress tends to suggest a poor prognosis. This is the first study to show a possible link between stressful life events and episodes of seborrheic dermatitis. It suggests the need to confirm these results through a study comparing patients with seborrheic dermatitis and subjects without the disease. It also shows that depression is more common among patients with facial involvement and that anxiety is an aggravating factor.     

Low levels of emotional awareness predict a better response to dermatological treatment in patients with psoriasis

BACKGROUND: Personality and emotional factors are thought to influence the onset of psoriasis, the occurrence of relapses, and the sensitivity of this condition to dermatological treatments. OBJECTIVE: To explore the relationships between emotional disorders and emotional information processing in the one hand, and psoriasis severity and response to treatment on the other. METHODS: We recruited 93 patients through an article in the local press. These patients attended three consultations. We evaluated psoriasis severity by Psoriasis Area and Severity Index (PASI) score and response to treatment by change in PASI score from baseline to the 3-month visit. We screened for comorbid mental disorders, using the Mini International Neuropsychiatric Interview. We used the Hospital Anxiety and Depression Scale to assess anxiety and depressive symptoms. Alexithymia (difficulty in identifying and expressing emotions) was evaluated with the 26-item version of the Toronto Alexithymia Scale (TAS-26) and the ability to integrate and differentiate emotions (emotional awareness) was assessed with the Lane and Schwartz Levels of Emotional Awareness Scale (LEAS). RESULTS: Forty patients presented at least one psychiatric diagnosis and 33 were considered alexithymic (TAS > or =73). No psychological score was associated with baseline PASI score, which was higher in men and positively correlated with disease duration. Patients who considered their disease to be stress-reactive tended to have lower LEAS scores (p = 0.052). At the 3-month visit, PASI scores had significantly improved in the subset of patients (n = 67) presenting severe psoriasis at inclusion (PASI >2); emotional awareness and anxiety scores had also improved in these patients (p < 0.001), but dermatological and psychological changes were not statistically related. Dermatological improvement at 3 months with respect to baseline PASI was predicted by longer disease duration (>20 years) and lower baseline LEAS score (p = 0.044 and p = 0.021, respectively). CONCLUSION: This study demonstrates the value of assessing the ability of patients with psoriasis to process emotional information, as defined by emotional awareness. Patients with low LEAS scores appear to be more reactive to stress, but also to be more responsive to treatment, suggesting the activation of a particular stress physiology by negative affective states that are not experienced.