involucrin and Dermatitis--Irritant

Detergents are skin irritants affecting keratinocytes. In this study, healthy volunteers were exposed to water (vehicle) and 1% sodium lauryl sulfate (SLS) under occlusive patch tests for 24 hours. The messenger RNA (mRNA) expression of keratinocyte differentiation markers and of enzymes involved in corneodesmosome degradation was examined in skin biopsies (n=8) during the repair phase (6 hours to 7 days postexposure) using real-time reverse-transcription PCR. It was found that the expression of involucrin was increased at 6 hours, but then rapidly normalized. The expression of transglutaminase 1 exhibited a twofold increase after 24 hours in the SLS-exposed skin. Profilaggrin was decreased after 6 hours. Later (4-7 days), the expression in SLS-exposed areas was >50% above than in control areas. An increased and altered immunofluorescence pattern of involucrin, transglutaminase 1, and filaggrin was also found (n=4). At 6 hours post-SLS exposure, the mRNA expression of kallikrein-7 (KLK-7) and kallikrein-5 (KLK-5) was decreased by 50 and 75%, respectively, as compared with control and water-exposed areas. Thereafter, the expression pattern of KLK-7 and KLK-5 was normalized. Changes in protein expression of KLK-5 were also found. In conclusion, SLS-induced skin barrier defects induce altered mRNA expression of keratinocyte differentiation markers and enzymes degrading corneodesmosomes.

Topics: Adult; Biopsy; Cell Differentiation; Dermatitis, Irritant; Female; Filaggrin Proteins; Humans; Intermediate Filament Proteins; Irritants; Kallikreins; Keratinocytes; Male; Middle Aged; Patch Tests; Protein Precursors; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Skin; Sodium Dodecyl Sulfate; Transglutaminases; Wound Healing

Previous studies demonstrated that peroxisome-proliferator-activated receptor (PPAR)-alpha or PPAR-delta activation stimulates keratinocyte differentiation, is anti-inflammatory, and improves barrier homeostasis. Here we demonstrate that treatment of cultured human keratinocytes with ciglitazone, a PPAR-gamma activator, increases involucrin and transglutaminase 1 mRNA levels. Moreover, topical treatment of hairless mice with ciglitazone or troglitazone increases loricrin, involucrin, and filaggrin expression without altering epidermal morphology. These results indicate that PPAR-gamma activation stimulates keratinocyte differentiation. Additionally, PPAR-gamma activators accelerated barrier recovery following acute disruption by either tape stripping or acetone treatment, indicating an improvement in permeability barrier homeostasis. Treatment with PPAR-gamma activators also reduced the cutaneous inflammatory response that is induced by phorbol 12-myristate-13-acetate, a model of irritant contact dermatitis and oxazolone, a model of allergic contact dermatitis. To determine whether the effects of PPAR-gamma activators are mediated by PPAR-gamma, we next examined animals deficient in PPAR-gamma. Mice with a deficiency of PPAR-gamma specifically localized to the epidermis did not display any cutaneous abnormalites on inspection, but on light microscopy there was a modest increase in epidermal thickness associated with an increase in proliferating cell nuclear antigen (PCNA) staining. Key functions of the skin including permeability barrier homeostasis, stratum corneum surface pH, and water-holding capacity, and response to inflammatory stimuli were not altered in PPAR-gamma-deficient epidermis. Although PPAR-gamma activators stimulated loricrin and filaggrin expression in wild-type animals, however, in PPAR-gamma-deficient mice no effect was observed indicating that the stimulation of differentiation by PPAR-gamma activators is mediated by PPAR-gamma. In contrast, PPAR-gamma activators inhibited inflammation in both PPAR-gamma-deficient and wild-type mouse skin, indicating that the inhibition of cutaneous inflammation by these PPAR-gamma activators does not require PPAR-gamma in keratinocytes. These observations suggest that thiazolidindiones and perhaps other PPAR-gamma activators maybe useful in the treatment of cutaneous disorders.

Topics: Animals; Cell Differentiation; Dermatitis, Irritant; Epidermis; Female; Filaggrin Proteins; Homeostasis; Hypoglycemic Agents; Keratinocytes; Male; Mice; Mice, Hairless; Mice, Transgenic; Protein Precursors; Receptors, Cytoplasmic and Nuclear; RNA, Messenger; Thiazolidinediones; Transcription Factors; Transglutaminases

Chronic irritant contact dermatitis (CICD) is characterized by erythema, scaling, hyperkeratosis, chapping and fissures. It may be the result of skin damage evoked by the cumulative effect of a variety of irritant stimuli. The diagnosis of CICD is made on basis of the patient's history and clinical features. No specific diagnostic tests are available.. The histopathologic and cell biological features of CICD have not been extensively studied. Here, we describe the histological and immunohistological changes in CICD.. Punch biopsies were taken from 11 patients with CICD for hematoxylin eosin and immunohistochemical stainings. Four skin biopsies of the palms of the hands of healthy volunteers served as controls.. The histopathologic pattern was characterized by different grades of hyperkeratosis, parakeratosis, spongiosis, exocytosis, acanthosis, and mononuclear perivascular infiltrates. Mitotic activity, as measured by Ki-67-staining in the epidermis, was increased fourfold in involved skin as compared with normal skin. Involucrin, a structural protein of the cornified envelope, was expressed from the stratum granulosum throughout the stratum spinosum in all patients with CICD and was upregulated in comparison with normal skin. Epidermal fatty-acid binding protein (E-FABP), a terminal differentiation marker, was proportionally unaltered in the CICD as compared with the normal skin and was localized from the stratum granulosum to the upper layers of the stratum spinosum. Cytokeratin 16, a differentiation marker expressed in hyperproliferative epidermis, was markedly increased from the stratum granulosum throughout the stratum spinosum in 5 out of 11 patients with CICD. Skin-derived antiproteinase (SKALP)/elafin, a proteinase inhibitor expressed in inflamed epidermis, was only detected within the stratum granulosum in 3 out of 11 patients.. We conclude that CICD is clinically characterized by features of a chronic dermatitis and, at the histological level, by inflammatory changes, epidermal hyperproliferation and altered differentiation.

Topics: Adolescent; Adult; Carrier Proteins; Cell Division; Chronic Disease; Dermatitis, Irritant; Fatty Acid-Binding Protein 7; Fatty Acid-Binding Proteins; Female; Humans; Immunohistochemistry; Male; Middle Aged; Myelin P2 Protein; Neoplasm Proteins; Protein Precursors; Proteinase Inhibitory Proteins, Secretory; Proteins; Skin; Tumor Suppressor Proteins

Although the induction of acute irritant dermatitis by detergents has been studied extensively in recent years, our understanding of the cell biological events in the repair phase, and its relevance for the development of chronic irritant dermatitis is limited. Here we studied the reaction pattern of human skin to short-term application of sodium dodecyl sulphate (SDS) in a model that induced a minimal acute inflammatory reaction (absence of polymorphonuclear leucocytes, PMN) and did not have cytopathic effects on the epidermal keratinocytes as determined by histological investigation. All parameters were measured up to 14 days after exposure to SDS. Application of SDS caused disturbances of barrier function as measured by transepidermal water loss and had vascular effects as judged by erythema. Several cell biological markers for epidermal growth and differentiation were examined by immunohistochemistry. A rapid and strong induction of the cornified envelope precursor protein involucrin was seen in the stratum spinosum, with a peak at 24 h. Within 24 h a strong upregulation of epidermal fatty acid binding protein (E-FABP) was noted, with a peak at 7 days after injury. Cellular proliferation in the basal layer was increased fivefold as assessed by nuclear staining for the Ki-67 antigen, showing a peak at 48 h. Surprisingly, no significant induction of cytokeratin 16 and SKALP/elafin expression, two markers associated with epidermal hyper-proliferation and inflammation, was seen. These findings suggest that the cellular changes following exposure to detergent are distinct from those seen in other forms of skin injury. We would speculate that the epidermal response to detergent exposure is primarily directed at restoration of barrier function.

Topics: Adult; Biomarkers; Carrier Proteins; Cell Differentiation; Cell Division; Dermatitis, Irritant; Detergents; Epidermis; Erythema; Fatty Acid-Binding Protein 7; Fatty Acid-Binding Proteins; Female; Humans; Keratinocytes; Keratins; Ki-67 Antigen; Male; Models, Biological; Myelin P2 Protein; Neoplasm Proteins; Protein Precursors; Proteinase Inhibitory Proteins, Secretory; Proteins; Sodium Dodecyl Sulfate; Time Factors; Tumor Suppressor Proteins

Allergic and irritant contact dermatitis are similar clinically, histologically and on immunohistochemistry. In the present investigation, we assessed whether study of the recruitment of cycling epidermal cells, and the expression of keratin 16 and involucrin, are of use in differentiating between the response to contact allergens and the response to the irritant detergent sodium lauryl sulphate. Both allergic and irritant challenges induced epidermal proliferation, and the expression of keratin 16 and involucrin, but the dynamics were different. Two and 3 days after challenge, a highly significant difference between the allergic and irritant reactions was observed with respect to involucrin expression assessed by MON-150 staining.

Topics: Adult; Aged; Cell Differentiation; Cell Division; Dermatitis, Allergic Contact; Dermatitis, Irritant; Epidermis; Female; Humans; Immunohistochemistry; Keratins; Male; Middle Aged; Protein Precursors; Time Factors