Increased nerve growth factor and its receptors in atopic dermatitis: an immunohistochemical study.
ABSTRACT Evidence suggests that neurotrophins may regulate certain immune functions and inflammation. In the present study, the localization and distribution of nerve growth factor (NGF) and its receptors were explored using immunohistochemical methods, with the aim of detecting the cause of the neurohyperplasia in early lesions of atopic dermatitis (AD). In AD involved skin, strong NGF-immunoreactive (IR) cells were observed in the epidermis. In some cases, a huge number of infiltrating cells with stronger NGF immunoreactivity was seen mainly in the dermal papillae. Some trkA immunoreactivity was observed in the outer membrane of cells in the basal and spinal layers of the epidermis. In the papillary dermis, a larger number of cells demonstrated strong trkA immunoreactivity. The p75 NGFr-IR nerve fibre profiles were increased (900 per mm(2); p<0.001) compared to normal [the involved skin also differed from the uninvolved skin (p<0.05)] in the dermal papillae. These nerve fibres were larger, coarser and branched, some of them terminated at p75 NGFr-IR basal cells, and also revealed a stronger fluorescence staining than the controls or the uninvolved skin. In normal healthy volunteers and AD uninvolved skin, the NGF immunoreactivity was weak in the basal layer of epidermis. Only a few trkA positive cells were seen in the basal layer of the epidermis and upper dermis. The IR epidermal basal cells revealed a striking patchy arrangement with strong p75 NGFr immunostaining in the peripheral part of the cells, and short and thick NGFr-IR nerve fibre profiles appeared as smooth endings scattered in the dermis including the cutaneous accessory organs. Using NGF and p75 NGFr double staining, both immunoreactivities showed a weak staining in the epidermis and dermis in normal and uninvolved skin. In the involved dermis of AD, the intensity of p75 NGFr-IR nerves was stronger in areas where there were also increased numbers of NGF-IR cells. These findings indicate that NGF and its receptors may contribute to the neurohyperplasia of AD.
Article: Overexpression of functional TrkA receptors after internalisation in human airway smooth muscle cells.[show abstract] [hide abstract]
ABSTRACT: Trafficking of the TrkA receptor after stimulation by NGF is of emerging importance in structural cells in the context of airway inflammatory diseases. We have recently reported the expression of functional TrkA receptors in human airway smooth muscle cells (HASMC). We have here studied the TrkA trafficking mechanisms in these cells. TrkA disappearance from the cell membrane was induced within 5 min of NGF (3pM) stimulation. Co-immunoprecipitation of clathrin-TrkA was revealed, and TrkA internalisation inhibited either by clathrin inhibitors or by siRNA inducing downregulation of endogenous clathrin. TrkA internalised receptors were totally degraded in lysosomes, with no recycling phenomenon. Newly synthesized TrkA receptors were thereafter re-expressed at the cell membrane within 10 h. TrkA re-synthesis was inhibited by blockade of clathrin-dependent internalisation, but not of TrkA receptors lysosomal degradation. Finally, we observed that NGF multiple stimulations progressively increased TrkA expression in HASMC, which was associated with an increase in NGF/TrkA-dependent proliferation. In conclusion, we show here the occurrence of clathrin-dependent TrkA internalisation and lysosomal degradation in the airway smooth muscle, followed by upregulated re-synthesis of functional TrkA receptors and increased proliferative effect in the human airway smooth muscle. This may have pathophysiological consequences in airway inflammatory diseases.Biochimica et Biophysica Acta 07/2008; 1783(10):1964-71. · 4.66 Impact Factor
Article: A Role of Staphyococcus aureus, Interleukin-18, Nerve Growth Factor and Semaphorin 3A, an Axon Guidance Molecule, in Pathogenesis and Treatment of Atopic Dermatitis.[show abstract] [hide abstract]
ABSTRACT: Staphylococcus aureus (SA) is usually present not only in the skin lesions of atopic dermatitis (AD) but also in the atopic dry skin. SA discharges various toxins and enzymes that injure the skin, results in activation of epidermal keratinocytes, which produce and release IL-18. IL-18 that induces the super Th1 cells secreting IFN-γ and IL-13 is supposed to be involved in development of AD and its pathogenesis. Indeed, the number of SA colonies on the skin surface and the serum IL-18 levels in patients with AD significantly correlated with the skin scores of AD lesions. Also, there is strong positive correlation between the skin scores and serum IL-18 levels in DS-Nh mice (P<0.0001, r=0.64), which develop considerable AD-like legions when they are housed under conventional conditions, but develop skin legions with less severity and less frequency under specific pathogens free (SPF) conditions. Therefore, they are well-known as model mice of AD, in which SA is presumed to be critical factor for the development of AD lesions. Also, theses DS-Nh mice pretreated with Cy developed more remarkable AD-like lesions in comparison with non-treated ones. The levels of INF-r and IL-13 in the supernatants of the lymph node cell cultures stimulated with staphylococcal enterotoxin B (SEB) or ConA were increased in the Cy-treated mice, although the serum levels of total IgE were not. In this experiment, we revealed that Cy-treated mice, to which CD25 +CD4 + reguratory T cells taken from non-treated ones had been transferred, developed the AD-like legions with less severity and less number of SA colonies on the skin surface. Therefore, it is presumed that CD25 +CD4 + reguratory T cells might be involved in the suppression of super Th1 cells which are induced by IL-18 and are involved in the development of AD-like lesions rather than IgE production. The efficient induction of CD25 +CD4 + reguratory T cells is expected for the new type of treatment of AD. We also found that farnesol (F) and xylitol (X) synergistically inhibited biofilm formation by SA, and indeed the ratio of SA in total bacteria at sites to which the FX cream containing F and X had been applied was significantly decreased 1 week later, accompanied with improvement of AD, when compared with that before application and at placebo sites. Therefore, the FX cream is a useful skin-care agent for atopic dry skin colonized by SA. The nerve growth factor (NGF) in the horny layer (the horn NGF) of skin lesions on the cubital fossa was collected by tape stripping and measured using ELISA in AD patients before and after 2 and 4 weeks treatments. Simultaneously, the itch and eruptions on the whole body and on the lesions, in which the horn NGF was measured, were recorded, and also the peripheral blood eosinophil count, serum LDH level and serum total IgE level were examined. The level of NGF was significantly higher in AD patients than in healthy controls, correlated with the severity of itch, erythema, scale/xerosis, the eosinophil count and LDH level, and also significantly decreased after treatments with olopatadine and/or steroid ointment for 2 and 4 weeks. Therefore, the measurement of the NGF by this harmless method seems to be useful to assess the severity of AD and the therapeutic effects on AD. In AD patients, C-fiber in the epidermis increase and sprout, inducing hypersensitivity, which is considered to aggravate the disease. Semaphorin 3A (Sema3A), an axon guidance molecule, is a potent inhibitor of neurite outgrowth of sensory neurons. We administered recombinant Sema3A intracutaneously into the skin lesions of NC/Nga mice, an animal model of AD, and investigated the effect of Sema3A on the skin lesions and their itch. Sema3A dose-dependently improved skin lesions and attenuated the scratching behavior in NC/Nga mice. Histological examinations revealed a decrease in the epidermal thickness, the density of invasive nerve fibers in the epidermis, inflammatory infiltrate including mast cells and CD4 +T cells, and the production of IL-4 in the Sema3A-treated lesions. Because the interruption of the itch-scratch cycle likely contributes to the improvement of the AD-like lesions, Sema3A is expected to become a promising treatment of patients with refractory AD.Allergy, asthma & immunology research 10/2010; 2(4):235-46. · 1.91 Impact Factor