New insights into the roles of myofibroblasts and innervation during skin healing and innovative therapies to improve scar innervation

During the resolution phase of normal skin wound healing, there is a considerable loss of various cell types, including myofibroblasts by apoptosis. Inappropriate delay of apoptosis, and thus increased survival of myofibroblasts, may be a factor leading to pathologies and excessive scarring. Considerable data now clearly suggest that innervation plays a major role in wound healing, including the modulation of fibroblast cellular activity. An abnormal level of neuromediators is implicated not only in the development of chronic wounds but also in excessive scar formation. Understanding interactions between neuromediators and myofibroblasts, allowing normal reinnervation and having adequate levels of neuromediators during the healing process are clearly important to avoid the appearance of pathological healing or fibrosis/scarring. The aim of this review was first to discuss the mechanisms leading to normal or excessive scarring and then to present the roles of innervation during wound healing. Finally, the latest therapeutic strategies to help wound repair and reinnervation after skin damage will be introduced. Advantages and limitations in the use of neuropeptides, growth factors and biomaterials will be discussed as well as the most recent studies on electrostimulation and the potential of targeting resident skin mesenchymal stem cells.     

Validation of a model of itch induction for brain positron emission tomography studies using histamine iontophoresis

Skin-brain signalling in itch reactions has been demonstrated with neuroimaging techniques showing specific brain activation. With positron emission tomography (PET), the itch model used must be adapted to technical and practical constraints. The technique of itch induction by histamine iontophoresis enables modulation of the sensation via the electrical charge applied. This itch model was validated on normal forearm skin of 56 subjects, with itch visual analogue scores peaking to approximately 1.0 cm after 3-4 min, falling to 0.2 cm at 15 min, with no influence of sex, zone, or order. Subsequently, the model was used in a PET study on 14 male volunteers, comparing histamine with physiological saline (control). The results show that the brain is able to discriminate these two conditions, with activated areas similar to those described previously, with, in addition, the anterior cingulate cortex and the insula being positively correlated with the intensity of the sensation.     

Depression and psoriasis

Psychiatric co-morbidity is very frequently associated with psoriasis. Depression is observed in numerous patients with psoriasis. Early detection and treatment are very important. There is a vicious circle psoriasis- alteration of quality of life- depression, but psoriasis improvement is not always followed by an improvement of depression. A contrario, it is obvious that a depressive patient has a bad observance of treatment. Links between psoriasis and depression are not only psychopathological. Biological factors, such as increase of blood amounts of substance P and TNF or decrease of serotonine could also explain this association.     

CD1-reactive leukemic cells in bone marrow: presence of Langerhans cell marker on leukemic monocytic cells.

Langerhans cells originate in bone marrow and probably belong to the monocyte-macrophage lineage. CD1 is a specific marker of Langerhans cells. By immunofluorescence and immunoelectron microscopy, CD1a antigen and myeloid markers (CD11, CD13, CD14, CD15, CD33, HLA-DR) were studied in 53 cases of acute myeloid leukemias (AML) and 3 acute lymphoblastic leukemias (ALL). The 11 ANLL without monocytic component were CD1a negative. 2/5 of acute myelomonocytic leukemias (AML4) and 9/37 of acute monocytic leukemias (AML5) were positive. All 3 ALL were negative. No correlation was found between CD1a and myeloid markers. CD1a+ AML did not differ from CD1a- AML with regard to cytogenetics or response to therapy. The CD1a positive cells may originate from an abnormal proliferation of CD1a positive cells which are present in bone marrow and which may differentiate into Langerhans cell precursors.