L. Domenici

Use of periodate-lysine-paraformaldehyde for the fixation of multiple antigens in human skin biopsies

Periodate-lysine-paraformaldehyde (PLP) has been proposed as a fixative for glycoprotein antigens which should stabilize periodate oxidized polysaccharide chains through lysine mediated crosslinks, either directly or by the intermediation of formaldehyde. In spite of premises and attempts reported in the literature, this fixative has never become popular for the study of membrane antigens of immune system cells, which leads to doubts on its real efficacy. We have addressed this issue in biopsies of human skin and found that PLP followed by cryoprotection with 30% sucrose and cryosectioning, or PLP fixation of isolated epidermal sheets, consistently provided for good preservation of morphology and intense labeling of major histocompatibility complex class II molecules, CD 1 a, CD4, CD8, E-cadherin, cytokeratins in general, cytokeratin-18 in particular, and bromodeoxyuridine, incorporated by cycling cells in vitro, and for the demonstration of tyrosinase enzyme activity. PLP-fixed, osmicated and epon-embedded epidermal sheets proved as good as sheets fixed with a mixture of formaldehyde and glutaraldehyde for electron microscopic morphological analysis. Also, these sheets were amenable to immunoperoxidase staining of Langerhans cell membrane antigen CD1a and keratinocyte membrane antigen E-cadherin before being osmicated and prepared for electron microscopy. In a parallel paper, we had also shown that oral mucosa biopsies fixed in PLP showed good morphology and immunolabeling of CD54, CD80, CD83 and CD86. Therefore, we conclude that PLP can be proposed as a multi-task fixative for light and electron microscopic analysis of membrane, cytoplasmic and nuclear antigens of immune system cells and keratinocytes.

Rosiglitazone Reduces The Inflammatory Response In A Model Of Vascular Injury In Rats

Thiazolidinediones are ligands that bind to and activate the nuclear peroxisome proliferator-activated receptor &ggr;. They are widely used as insulin sensitizers for the treatment of type 2 diabetes. Several studies have implicated the peroxisome proliferator-activated receptor &ggr; agonists rosiglitazone and pioglitazone in inflammatory events. To assess the anti-inflammatory properties of rosiglitazone, we investigated its effects on the molecular and cellular inflammatory response induced by a carotid injury in the rat. Male Wistar rats were randomized into a rosiglitazone-treated group (10 mg kg−1 day−1) and a control group (0.9% w/v NaCl). The drug or vehicle was administered by gavage for 7 days before carotid injury and for up to 21 days after injury. The inflammatory markers p38 mitogen-activated protein kinase, cyclooxygenase 2, nuclear factor-&kgr;B, and heat shock protein 47 and the influx and activity of cells in response to injury were measured. Rosiglitazone treatment significantly reduced the expression of the inflammatory markers compared with control group. p38 mitogen-activated protein kinase and nuclear factor-&kgr;B started to decrease a few hours after injury, whereas cyclooxygenase 2 and heat shock protein 47 expression decreased 7 and 14 days, respectively, after injury. Rosiglitazone also reduced neointima formation and inflammatory cell infiltration. In conclusion, rosiglitazone negatively regulated the inflammatory events involved in tissue repair at molecular and cellular levels. These results suggest that rosiglitazone plays a protective role in inflammatory vascular diseases.

Evolution of Endotoxin-Induced Lung Injury in the Rat beyond the Acute Phase

Objectives: Intratracheal endotoxin in rats causes acute lung injury. Here we have addressed the cellular physiopathology of lung recovery from that injury. Methods: The lungs of 5 untreated rats and rats treated with intratracheal endotoxin from 2, 3, 5, 8 (5 rats each) and 15 days (2 rats) were studied by light and electron microscopy and immunohistochemistry. Results: In the acute phase there was a reduction in the aerated spaces (p < 0.01); diffuse infiltration of granulocytes and macrophages; hyperplasia of type-II pneumocytes, and hypertrophy of interstitial cells. Aerated spaces improved during recovery. In the early recovery phase (3–8 days) the compartmentalization of infiltrating cells varied significantly (p < 0.01): macrophages remained widespread while neutrophils were inside blood vessels. Many pneumocytes were intermediate between type-I and type-II cells. In the late recovery phase (15 days) the infiltrate disappeared; myofibroblasts were significantly more than previously (p < 0.01) and extracellular matrix was abundant; type-II pneumocytes contained non-lamellated lipid inclusions. Conclusions: Macrophages play a pivotal role in the damage-repair processes of the lung following endotoxin injury, leading to an increase in extracellular matrix, differentiation of myofibroblasts and altered secretion of surfactant by newly differentiated type-II pneumocytes.

Early apoptosis plays an important role in the healing mechanism of cutaneous basal cell carcinomas after photodynamic therapy

SIR, Mycosis fungoides (MF) is characterized by clonal helper ⁄ memory (CD4+ CD45RO+) T-cells in the epidermis, whereas follicular mucinosis or alopecia mucinosis has perifollicular T-cell infiltrates and may clinically resemble alopecia areata. Bexarotene is the first retinoid X receptor (RXR)-selective retinoid shown to be effective for cutaneous T-cell lymphoma. Bexarotene has recently been shown to induce T-cell apoptosis in vitro. Although bexarotene oral and topical gel are effective for MF, this is the first report, to our knowledge, of reversal of associated alopecia. Five patients with alopecia secondary to MF or follicular mucinosis were observed among a cohort of over 90 patients receiving bexarotene therapy at the M.D. Anderson Cancer Center. Their demographic data, degree of hair loss, skin biopsy results and drug administration are shown in Table 1. The location of the hair loss was confined to the scalp in four patients and to the extremities in a fifth. All of the skin biopsy specimens revealed atypical CD4+ CD8+ perifollicular lymphocytic infiltrates, and two showed mucin deposits consistent with follicular mucinosis. Three patients had scaling with negative fungal cultures. Patients with early stage MF were treated with topical bexarotene therapy and advanced stage patients with oral bexarotene. The MF as well as the alopecia improved in all five patients, irrespective of the route of delivery. Hair regrowth began within 2–9 months and full regrowth was evident by 1Æ5 years. Patient 1. A 77-year-old Native American woman presented with a 3-month history of a single patch of alopecia accompanied by pruritus and mild tenderness, generalized xerosis, fatigue and a 4Æ5-kg unintentional weight loss. Asthma and childhood eczema were noted. There was a 4 · 5 cm alopecia areata-like lesion with scaling on the scalp (Fig. 1a) and macular erythema of less than 1%. An atypical CD4+ CD8– clonal lymphocytic infiltrate and mucin deposits were present in the follicular epithelium. After applying 1% bexarotene gel daily to the leg and scalp lesions, partial hair regrowth was present at 3 months (Fig. 1b), with full regrowth of terminal grey hair covering the former patch of alopecia at 5 months (Fig. 1c). Patient 2. A 64-year-old Hispanic man with dermatitis for 30 years developed generalized exfoliative erythroderma, patchy alopecia, and a skin biopsy consistent with MF. He had increased fatigue, chills, night sweats and intense pruritus. On examination, he had generalized exfoliative erythroderma and lymphadenopathy. On the scalp, multiple round alopecia areata lesions, patches of white hair, and exclamation point hairs were observed (Fig. 2a,b). An atypical CD4+ CD8+ dermal infiltrate with epidermotropism and a clonal T-cell receptor gene rearrangement were observed in

Langerhans Cell Histiocytosis of the Vulva: An Ultrastructural Study

Langerhans cells histiocytosis (LCH) is a proliferative disorder of Langerhans cells. The lesions are normally characterized by infiltration of eosinophils, neutrophils, lymphocytes, plasma cells, and Langerhans cells. The specific cells of LCH contain Birbeck granules, express the phenotype of Langerhans cells but with markers fixed at an early stage of activation, and are functionally defective in antigen-presenting ability. The disease most often affects children; when it occurs in older patients, anal and groin involvement is quite common and vulvar lesions can be found in older females. The authors report a case of a 64-year-old woman with LCH of the vulva and diabetes insipidus. An immunohistochemical and ultrastructural study of the vulvar lesions showed an infiltrate in which antigenically and morphologically mature Langerhans cells, monocytoid cells, and cells with an intermediate phenotype between monocytes and Langerhans cells were concurrently observed. Although the clinical and histological aspects of LCH are well established, the pathogenetic mechanism of lesions is not yet known. The finding of an infiltrate composed by Langerhans cells and many putative precursors of these cells suggests the hypothesis of an in situ differentiation of Langerhans cells from immature monocytoid precursors.

Dendritic cells with lymphocyte stimulating activity differentiate from human CD133 positive precursors

CD133 is a hallmark of primitive myeloid progenitors. We have addressed whether human cord blood cells selected for CD133 can generate dendritic cells, and Langerhans cells in particular, in conditions that promote that generation from CD34(+) progenitors. Transforming growth factor-β1 (TGF-β1) and anti-TGF-β1 antibody, respectively, were added in some experiments. With TGF-β, monocytoid cells were recognized after 7 days. Immunophenotypically immature dendritic cells were present at day 14. After 4 more days, the cells expressed CD54, CD80, CD83, and CD86 and were potent stimulators in mixed lymphocyte reaction; part of the cells expressed CD1a and langerin, but not Birbeck granules. Without TGF-β, only a small fraction of cells acquired a dendritic shape and expressed the maturation-related antigens, and lymphocytes were poorly stimulated. With anti-TGF-β, the cell growth was greatly hampered, CD54 and langerin were never expressed, and lymphocytes were stimulated weakly. In conclusion, CD133(+) progenitors can give rise in vitro, through definite steps, to mature, immunostimulatory dendritic cells with molecular features of Langerhans cells, although without Birbeck granules. Addition of TGF-β1 helps to stimulate cell growth and promotes the acquisition of mature immunophenotypical and functional features. Neither langerin nor Birbeck granules proved indispensable for lymphocyte stimulation.

Tacrolimus causes reduced GLI1 expression and phenotypic changes in the TE 354.T basal cell carcinoma cell line

[8] Chapkin RS, Ziboh VA, Marcelo CL, Voorhees JJ. Metabolism of essential fatty acids by human epidermal enzyme preparations: evidence of chain elongation. J Lipid Res 1986;27(9):945–54. [9] Cho HP, Nakamura M, Clarke SD. Cloning, expression, and fatty acid regulation of the human delta-5 desaturase. J Biol Chem 1999;274(52):37335–9. [10] Cho HP, Nakamura MT, Clarke SD. Cloning, expression, and nutritional regulation of the mammalian Delta-6 desaturase. J Biol Chem 1999;274(1):471–7.