British Journal of Dermatology

CAMERON, M.M.

doi: 10.1046/j.1365-2133.1997.1760185.xpmid: N/A

SummaryHouse dust mite (HDM) allergens are the most important triggers for atopic dermatitis. Reducing exposure to these allergens may alleviate clinical symptoms. Chemicals with acaricidal activity have been used to treat upholstered furniture, carpets and bedding with the aim to reduce HDM allergen exposure. These chemicals, by reducing HDM, can decrease the concentration of mite allergens in dust but improvements in clinical symptoms are not always apparent. Clinical improvement is more likely to occur if bedding has been treated rather than carpets and upholstery. Future control strategies should be aimed at treating bedding. Permethrin is a very efficient killer of mites. It is used topically to treat scabies and head lice and is impregnated in bed nets to prevent mosquito bites. Even when applied to the skin in high concentrations, it has a very low toxicity in humans and other mammals. Permethrin‐impregnated bedding may prove to be the best control method in the treatment of HDM allergen‐triggered atopic conditions.

ISHIDA‐YAMAMOTO, A.; HASHIMOTO, Y.; MANABE, M.; O'GUIN, W.M.; DALE, B.A.; HZUKA, H.

doi: 10.1046/j.1365-2133.1997.17611855.xpmid: N/A

SummaryFilaggrin and trichohyalin are keratin intermediate filament‐associated proteins, and are primarily expressed in the granular cells of the epidermis and in the inner root sheath cells of the hair follicles, respectively. These two proteins are, however, occasionally co‐expressed in some tissues. To gain more insights into the mechanisms for expression and processing of (pro)filaggrin and trichohyalin during various pathways of epithelial differentiation, we compared their localization by double immunostaining techniques in normal and psoriatic epidermis, tongue filiform papillae and cultured human epidermal keratinocytes. In normal foreskin, trichohyalin immunoreactive cells were observed only occasionally and, when present, they always co‐expressed filaggrin. Trichohyalin expression occurred, however, in filaggrin‐negative cells as well as in filaggrin‐positive cells in the psoriatic epidermis, tongue papillae and cultured keratinocytes. Filaggrin and trichohyalin were induced independently at different times following calcium shift in cultured keratinocytes. Immunoelectron microscopy demonstrated the distinct intracellular distribution of filaggrin and trichohyalin. Some filaggrin granules were observed in the cells where trichohyalin was diffusely distributed. Likewise some trichohyalin granules were found in the cells with diffuse filaggrin labelling. These results suggest the existence of distinct expression/processing mechanisms of filaggrin and trichohyalin in differentiating keratinocytes.

HAYNES, S.L.; SHUTTLEWORTH, C.A.; KIELTY, C.M.

doi: 10.1046/j.1365-2133.1997.1762185.xpmid: N/A

SummaryFibrillin–containing microfibrils are key architectural structures of the upper dermis and integral components of the dermal elastic fibre network. Microfibril bundles intercalate into the dermal—epithelial junction and provide an elastic connection between the dermal elastic fibre network and the epidermis. Immunohistochemical studies have suggested that they are laid down both at the dermal—epithelial junction and in the deep dermis. While dermal fibroblasts are responsible for deposition of the elastin and microfibrillar components that comprise the elastic fibres of the deep dermis, the cellular origin of the microfibril bundles that extrude from the dermal—epithelial junction is not well defined. We have used fresh tissues, freshlyisolated epidermis and primary human and porcine keratinocyte cultures to investigate the possibility that keratinocytes are responsible for deposition of these microfibrils. We have shown that keratinocytes in vivo and in vitro synthesize both fibrillin‐1 and fibrillin‐2, and assemble beaded microfibrils concurrently with expression of basement membrane collagen. These observations suggest that keratinocytes co‐ordinate the secretion, deposition and assembly of these distinct structural elements of the dermal matrix, and have important implications for skin remodelling.

WESTGATE, G.E.; TIDMAN, N.; BERKER, D.DE.; BLOUNT, M.A.; PHILPOTT, M.P.; LEIGH, I.M.

doi: 10.1046/j.1365-2133.1997.1763184.xpmid: N/A

SummaryThe hair follicle is a heterogeneous tissue involving differentiation of both hair forming (trichocyte) and non‐hair forming (root sheath) cells; while there are many antibody markers available which can determine the distribution of ‘soft’ epithelial keratins, fewer have been described which are truly monospecific for hair specific ‘hard’ keratins. We employed the proven strategy of raising monoclonal antibodies to a short synthetic peptide from the carboxy‐terminal sequence of mouse Ha1 and report here the successful production of a monospecific monoclonal antibody which we have called LHTric‐1. We have characterized the antibody using immunostaining on rat and human tissues and by immunoblotting against an extract of human follicles. The antibody cross‐reacted between rat and human tissue but did not stain formalin‐fixed tissue. LHTric‐1 localized very specifically to the pre‐cortical region of the hair follicle in early anagen and to pre‐cortical cells in the upper bulb in anagen. Telogen follicles did not react. LHTric‐1 immunoreacted within tongue and nail, staining being restricted to the mid‐line above the connective tissue core in tongue and to the suprabasal layers of the nail matrix. The antibody did not react with the fully keratinized hair or nail plate. Finally, in immunoblotting. LHTric‐1 reacted with a single band of 44kDa, suggesting that a single protein was recognized. We conclude that this antibody, by virtue of its known antigen sequence specificity, will be useful in research into the formation of hair and nail in normal and diseased states.

COMMO, S.; BERNARD, B.A.

doi: 10.1046/j.1365-2133.1997.17641854.xpmid: N/A

SummaryThe transition from the growth phase (anagen) to the involution phase (catagen) involves profound morphological changes in the human hair follicle. Club hair and epithelial column formation, for example, are key features of the catagen phase, which result in the disruption of physical interaction between the bulb and the dermal papilla. However, the dynamics and tissue remodelling that occur during this involution process remain largely unknown. Using monoclonal antibodies directed against K14 keratin, trichohyalin, transglutaminase I, desmoglein and Ki67 antigen, we followed the movements of each of the main hair follicle compartments during the onset of catagen. Our results indicate that the inner root sheath is an early target in this process, suggesting a key role for this compartment in the maintenance of hair follicle homeostasis.

BÖNI, R.; BURG, G.; DOGUOGLU, A.; ILG, E.C.; SCHÄFER, B.W.; MÜLLER, B.; HEIZMANN, C.W.

doi: 10.1046/j.1365-2133.1997.17651853.xpmid: N/A

SummaryThe purpose of this study was to evaluate the expression of the Ca2+‐binding S100 proteins S100A1. S100A2, S100A3, S100A4, S100A6 and S100B in normal skin. These immunohistochemical staining patterns were compared with those in melanocytic lesions. Parafin‐embedded tissue of normal skin adjacent to 26 naevi. 39 primary cutaneous melanomas and 14 cutaneous melanoma metastases was incubated with polyclonal antibodies against the recombinant human S100 proteins (S100A1, S100A2, S100A3, S100A4, S100A6, S100B) using the alkaline phosphatase anti‐alkaline phosphatase method. The S100A2 antibody stained the basal layer of the epidermis an hair follicles of normal skin. Four of 39 primary cutaneous melanomas were positive for S100A2, whereas none of the methastases or naevi showed any immunoreactivity. The S100A3 antibody only stained the inner root sheath cuticle of some hair follicles but no melanocytes or melanocytic lesions. Staining of S100A4 was weak and thus omitted to further analysis. S100A6 faintly labelled keratinocytes. Langerhans' cells, melanocytes and sweat glands. S100A6 immunoreaction was found in two of seven junctional naevi, five of seven compund naevi, and all dermal and blue naevi. There was an intense cytoplasmatic reaction for S100A6 in all primary cutaneous melanomas and in nine of 14 (64%) metastases. S100B was positive in melanocytes and Langerhans' cells, all primaries as well as in the metastases. S100A1 protein was not detected on any of the tissue specimens examined. Whereas S100B and S100A6 antibodies are useful markers for malignant melanoma, expression of S100A4 antibody is too low to be used for immunohistochemical staining. S100A1 and S100A3 antibodies are not expressed in melanocytic lesions and S100A2 is only found in selected tumours. The investigated S100 proteins, including S100B and S100A6, are also expressed in selected elements of normal skin. These findings are important for correct interpretation of staining patterns, when S100 antibodies are used as markers for melanoma or other tumours.

PARAMIO, J.M.; JORCANO, J.L.

doi: 10.1046/j.1365-2133.1997.17661858.xpmid: N/A

SummaryDifferent chemicals that specifically and selectively inhibit or activate protein kinases have been used to define the possible roles of these enzymes in the different steps of epidermal differentiation. Using HaCaT keratinocytes as a model, and under conditions in which cell proliferation is minimally affected, we found that tyrosine kinase inhibition leads to an inhibition of early (spinous: keratin K 10 expression) and late (granulosum: involucrin expression) differentiation processes, cGMP‐ and cAMP‐dependent protein kinases appear to modulate the transition form spinous to granular differentiation, a process which seems to be negatively controlled by protein phosphatases. Finally, enzymes belonging to the protein kinase C family appear to facilitate the transition from spinous to granular differentiation programmes while inhibiting the early steps of epidermal differentiation.

KARONEN, T.; JESKANEN, L.; KESKI‐OJA, J.

doi: 10.1046/j.1365-2133.1997.17671859.xpmid: N/A

SummaryLatent transforming growth factor‐β1 (TGF‐β1) and its binding protein‐1 (LTBP‐1) are components of the extracellular matrix microfibrils of cultured human fibroblasts. Using immunohistochemistry we have studied the localization of TGF‐β1 and LTBP‐1 and compred their distribution iwth that of elastic fibres in the interstitial connective tissue matrix of the human dermis. Prominent LTBP‐1 specific fibrillar staining co‐localized with the elastic fibres in normal human skin. Co‐distribution was also observed in a number of pathological states of the elastic fibres such as solar elastosis, solar keratosis and pseudoxanthoma elasticum. TGF‐β1 had a staining pattern similar to that of LTBP‐1 in solar elastosis and solar kertosis. No staining for LTBP‐1 or TGF‐β1 was found in dermis devoid of elastic fibres, as in anetoderma. LTBP‐1 is released from the extracellular matrix of cultured human fibroblasts, epithelial and endothelial cells by proteases. Analyogously, the immunoreactivity for LTBP‐1 and TGF‐β1 were also lost form the skin sections by elastase, and by trypsin, a protease pretreatment commonly used in immunohistochemistry. These results indicate that LTBP‐1 is a component of the elastin‐associated microfibrils of the interstitial connective tissue matrix of human skin. Furthermore, the small latent form of TGF‐β1 is likely to associate with the extracellular matrix of human dermis via LTBP‐1. The release of latent TGF‐β1 from the matrix, as a consequence of proteolytic cleavage of LTBP‐1, is a plausible extracellular mechanism for the regulation of TGF‐β1 activation.

D'AURIA, L.; FEI, P.CORDIALI; PIETRAVALLE, M.; FERRARO, C.; MASTROIANNI, A.; BONIFATI, C.; GIACALONE, B.; AMEGLIO, F.

doi: 10.1046/j.1365-2133.1997.1768185.xpmid: N/A

SummarySoluble E(sE)‐selectin represents the soluble isoform of cellular E‐selectin, an adhesion molecule synthesized only by endothelia cells. As a consequences. It may be considered a marker of endothelial activity. The aim of this study was therefor to evaluate the serum levels of sE‐selectin in nine patients affected with pemphigus vulgaris (PV) and in 15 patients with bullous pemphigoid(BP). Higher amounts of sE‐selectin, median 40.3 ng/mL, range 30–109.6 were found in the patients when compared with 20 healthy individuals, median 28.5ng/mL. range 6.4–48: P<0.01, matched for sex and age. These levels were also significantly correlated with the number of detectable lesions (r= 0.63, P<0.001) when the patient data were considered at the time of the first observation. Thirteen subjects were followed over time for a maximum of 3 months (from three to seven observations). During therapy, the number of lesions and the serum sE‐selectin values decreased concomitantly. Differently from sEselectin, the serum soluble intercellular adhesion molecule‐1 (sICAM‐1) values were not significantly differenent in the patients form the controls and showed no correlation with the serum sE‐selectin concentrations or with the number of lesions. The data presented point to the possible use of sEselecti determinations as a non‐specific follow‐up marker, suitable to gauge disease intensity over time and emphasize that endothelial activation is present in BP as well as in PV. Correspondence: Franco Ameglio, MD, Istituto S, Gallicano, Via S. Gallicano 25/A. 00153 Roma. Italy.

NIBBERING, P.H.; THIO, B.; BEZEMER, A.C.; BEIJERSBERGEN, R.L.; ZOMERDIJK, T.P.L.

doi: 10.1046/j.1365-2133.1997.1769185.xpmid: N/A

SummaryMonomethylfumarate (MMF), the most active metabolite of the new antipsoriasis drug FumadermR, stimulates an anti‐inflammatory mediator profile in human leucocytes and inhibits the proliferation of keratinocytes. These effects of MMF on cells in vitro may in part explain the beneficial action of FumadermR in patients. In addition, we have reported that MMF stimulates an increase in the intracellular free Ca2+ concentration ([Ca2+]i) and the cyclic adenosine monophosphate (cAMP) concentration in granulocytes and keratinocytes. Because Ca2+ and cAMP control many physiological cellular responses, including cell proliferation and inflammatory mediator production, the present study focused on the intracellular signal transduction pathway which links interaction between MMF and granulocytes with increases in [Ca2+]i and the cAMP concentration. The increase in [Ca2+]i in granulocytes after MMF depended both on extracellular Ca2+ and Ca2+ from intracellular stores. Ca2+ is essential for the increase in the cAMP concentration after stimulation with MMF. The results found for pharmacological inhibitors of various protein kinases suggest that a staurosporine‐sensitive protein kinase different from protein kinase C (PKC) and protein kinase A is involved in the MMF‐induced increase in [Ca2+]i in granulocytes. As MMF activated protein tyrosine kinase (PTK), and inhibition of this protein kinase partially reduced the increase in [Ca2+]i in granulocytes, PTK activitiy most likely is involved. In addition, activation of protein kinase histone 4 (PKH4) probably plays a part in the MMF ‐stimulated increase in [Ca2+]i in granulocytes as well. As MMF stimulated an increase in the GTP ‐ase activity of membranes and pertussis toxin (PTX) inhibited the increase in the [Ca2+]i and PKH4 activity of granulocytes stimulated by this compound, it is concluded that MMF activates PTX‐sensitive G proteins. Competition binding studies with radiolabelled dimethylfumarate (DMF) and unlabelled DMF and MMF revealed the presence of specific binding sites for methylated fumarates on granulocytes. In summary, MMF binds to specific sites on the plasma membrane of cells. This interaction activates pertussis toxin‐sensitive G proteins which then stimulate an increase in PTK and PKH4 activity. These protein kinases may regulate the rise in [Ca2+]i and the intracellular cAMP concentration. Elevated [Ca2+]i and intracellular cAMP concentration stimulate protein kinases that regulate transcription factors. Activation of these factors results in induction of downstream gene expression and thus controls cell functions, e.g. cell proliferation and production of inflammatory mediators, as has been found for cells incubated with MMF.