Contact sensitivity to Candida albicans--comparative studies in man and animal (guinea-pig)

Barrier Function, Epidermal Differentiation, and Human β-Defensin 2 Expression in Tinea Corporis

Tinea corporis is a superficial mycotic infection resulting in substantial epidermal changes. We determined skin barrier function, epidermal differentiation, and human-beta-defensin 2 (hBD-2) protein expression in 10 patients with tinea corporis caused by Trichophyton rubrum (T. rubrum). We found disturbed skin barrier function as shown by a significant increase in transepidermal water loss (TEWL) and specific ultrastructural changes including disturbed formation of extracellular lipid bilayers, lamellar body extrusion, and deposit of clotted material at the stratum granulosum/stratum corneum interface. Epidermal proliferation in tinea increased several fold and accordingly, proliferation and inflammation-associated keratins K6, K16, and K17 were expressed. Expression of basal keratins K5 and K14 increased, whereas differentiation-associated K10 was reduced. Reduction of the cornified envelope proteins involucrin, loricrin, and the S100 protein filaggrin was also seen. Reduced filaggrin expression correlated with reduced skin hydration; protein breakdown products of filaggrin have been shown to be important for water binding. Surprisingly, we found pronounced epidermal protein expression of hBD-2, which may be related to disturbed epidermal differentiation and inflammation. hBD-2 showed a weak, although significant, antifungal activity against T. rubrum in the turbidimetric assay and the immunohistological staining was somewhat less pronounced in areas directly underneath fungal hyphae in the stratum corneum. Together, we describe profound changes in skin barrier structure and function, epidermal proliferation, and differentiation including pronounced protein expression of hBD-2 in tinea corporis.

Patch test responses toMalassezia pachydermatisin healthy dogs

The effects of the patch test application of Malassezia pachydermatis extracts to normal canine skin were evaluated in eight healthy beagle dogs. Antigens (4 and 0.4 mg/ml) and saline controls were applied for 48 h using filter paper discs in Finn chambers. At the first test, two dogs showed patch test reactivity 20 min and 24 h after patch removal. Four out of six dogs that did not react to the first patch test showed reactivity when re-tested on day 8. Two remaining dogs were patch tested for a third time on day 15, after 7 days of cutaneous challenge with suspensions of M. pachydermatis cells, but failed to display reactivity. Positive patch test reactions were characterized histologically by mild epidermal hyperplasia, superficial dermal oedema and mild to moderate perivascular, periadnexal and interstitial infiltrates of neutrophils and CD3+ lymphocytes. Four dogs showed delayed intradermal test reactivity to M. pachydermatis antigens but intradermal and patch test reactivity did not correlate. This study indicates that patch test reactivity to M. pachydermatis antigen occurs in some healthy dogs exposed to the yeast, or may develop after a short period of antigen exposure. Further studies of patch test reactivity are warranted in dogs with disease associated with this cutaneous yeast.

Environmental effects on the functions of the stratum corneum

The stratum corneum (SC) is such an efficient barrier that only 2-5 g per h per cm2 of transepidermal water loss (TEWL) occurs in normal skin. The SC also plays another important role at the skin surface in keeping our skin smooth and flexible by binding water. We exposed a simulation model of in vivo SC to various, excessive physical insults in vitro, such as irradiation with 1 J per cm2 of UVB, 50 J per cm2 of UVA, or 3000 rad of X-ray, heating at 90 degrees C for 3 min, freezing at -196 degrees C for 60 s or repeated placement in an extremely dry or humid condition. None of them could cause any permanent change in the SC functions. Only the application of chemical agents such as lipid solvents or a detergent or the affliction of trauma resulted in a functional derangement of the SC. Because the viable skin tissues are more vulnerable to the effects of the environment than the SC, most of the abnormalities of the SC functions developing after environmental insults are secondarily caused by enhanced epidermal proliferation induced under the influence of underlying inflammation. These functional abnormalities were found to be demonstrable with biophysical measurements long after the disappearance of skin redness, the clinically observable sign of inflammation. The SC abnormalities in inflamed skin are also detectable as a change in the content of chemical mediators. For example, the ratio between proinflammatory IL-1 and its receptor antagonist (IL-1ra) whose production by epidermal keratinocytes is markedly enhanced by various proinflammatory stimuli, showed a deviation towards an excess of the latter in inflammatory skin. Facial skin that is always exposed to the environment is unique in that its SC shows such a deviation in the IL-1/IL-1ra ratio suggestive for the presence of mild inflammation even in normal individuals.

Experimental Candida albicans lesions in healthy humans: dependence on skin pH

The addition of suspensions of Candida albicans cells under occlusion to the left and right forearms, buffered at 2 different pH levels (6.0 and 4.5), resulted after 24 h in unilateral or bilateral lesions in 14 of 15 volunteers. The resulting skin-surface pH was 5.7+/-0.3 and 5.1+/-0.2, respectively. The lesions were more pronounced on the arm with the higher pH in all 14 subjects who reacted. In 11 cases, reactions occurred only on the arm with the higher pH. The pH-induced results are not due to inhibited growth of C. albicans. They may be due to a pH dependence of the yeast's virulence capacity and/or a modulation of the host's defence ability. The use of skin-occlusive products (e.g. dressings, diapers and panty liners) is known to raise skin pH and is associated with skin infections of C. albicans. An acidic buffer incorporated in such products could be a preventive measure for Candida-induced skin rash.

Reduced proliferative responses of peripheral blood mononuclear cells specifically to Candida albicans antigen in patients with atopic dermatitis--comparison with their normal reactivity to bacterial superantigens

Although reduced cutaneous reactivities to Candida albicans have been reported in patients with atopic dermatitis (AD), there is still controversy as to whether the in vivo lymphocyte proliferation response is normal or reduced. We have also reported that patients with AD manifest a decreased cutaneous response only to C. albicans antigen in scarification patch tests. The purpose of this study was to examine whether patients with AD show normal lymphocyte transformation responses to C. albicans antigen. Peripheral blood leucocytes (PBL) from 21 patients with AD and 14 healthy control (HC) subjects were cocultured with optimal concentrations of C. albicans antigen and of superantigens (staphylococcal enterotoxin A and B). PBL from the patients with AD showed a significantly lower response to C. albicans antigen, but there was no statistically significant difference in PBL responses to superantigens between the patients with AD and the HC subjects. This decreased proliferative response of PBL was particularly noticeable in those whose RAST scores for C. albicans antigen were high. These results suggest the development of a specific anergy to C. albicans antigen in patients with AD.

The role of complement-derived mediators in inflammatory skin diseases

The complement system represents an important nonspecific skin defense mechanism. Its activation leads to the generation of products that not only help to maintain normal host defenses but also mediate inflammation and tissue injury. Proinflammatory products of complement include large fragments of C3 with opsonic and cell-stimulatory activities (C3b and C3bi), low molecular weight anaphylatoxins (C3a, C4a, and C5a), and membrane attack complex. Among them C5a or its degradation product C5a des Arg seems to be the most important mediator because it exerts a potent chemotactic effect on inflammatory cells. Intradermal administration of C5a anaphylatoxin induces skin changes quite similar to those observed in cutaneous hypersensitivity vasculitis that occurs through immune complex-mediated complement activation. Complement activation is involved in the pathogenesis of the inflammatory changes in autoimmune bullous dermatoses. In pemphigus complement activation by pemphigus antibody in the epidermis seems to be responsible for the development of characteristic inflammatory changes termed eosinophilic spongiosis. In bullous pemphigoid (BP) interaction of basement membrane zone antigen and BP antibody leads to complement activation that seems to be related to leukocytes lining the dermoepidermal junction. Resultant anaphylatoxins not only activate the infiltrating leukocytes but also induce mast cell degranulation which facilitates dermoepidermal separation and eosinophil infiltration. Similar complement activation seems to play a more direct role in the dermoepidermal separation noted in epidermolysis bullosa acquisita and herpes gestationis. Anaphylatoxin generation via the alternative pathway activation under light irradiation is implicated in the development of the immediate erythematous phototoxic reactions induced by such well-known chemicals as porphyrin, chlorothiazide, demethylchlortetracycline, and chlorpromazine.(ABSTRACT TRUNCATED AT 250 WORDS)

Inability to produce white dermographism in the early stage of infantile eczema

White dermographism constitutes an abnormal vascular reaction characteristically demonstrable in atopic dermatitis; however, there is no information about it in the infantile phase of atopic dermatitis. Therefore we examined 73 infants younger than 3 years of age with eczematous dermatitis for the demonstrability of white dermographism after mechanical stroking of the lesional skin. None of the 40 healthy control infants showed white dermographism on their normal skin. In contrast, an age-dependent increase was demonstrated in patients with infantile eczema, from 11% in those 1 to 2 months of age to 85% in those older than 7 months. There was no correlation between the demonstrability of white dermographism in early infancy and the prognosis of infantile eczema. Based on our study of various types of dermatitis experimentally induced in adult volunteers, we think that, in addition to the immaturity of infantile skin, the presence of acute dermatitic changes may be related to inability to demonstrate white dermographism in the early phase of infantile eczema.