Skin barrier in atopic dermatitis: beyond filaggrin.

Atopic dermatitis is a chronic inflammatory skin disease with a complex pathogenesis, where changes in skin barrier and imbalance of the immune system are relevant factors. The skin forms a mechanic and immune barrier, regulating water loss from the internal to the external environment, and protecting the individual from external aggressions, such as microorganisms, ultraviolet radiation and physical trauma. Main components of the skin barrier are located in the outer layers of the epidermis (such as filaggrin), the proteins that form the tight junction (TJ) and components of the innate immune system. Recent data involving skin barrier reveal new information regarding its structure and its role in the mechanic-immunological defense; atopic dermatitis (AD) is an example of a disease related to dysfunctions associated with this complex.

Skin barrier in atopic dermatitis: beyond filaggrin

Abstract: Atopic dermatitis is a chronic inflammatory skin disease with a complex pathogenesis, where changes in skin barrier and imbalance of the immune system are relevant factors. The skin forms a mechanic and immune barrier, regulating water loss from the internal to the external environment, and protecting the individual from external aggressions, such as microorganisms, ultraviolet radiation and physical trauma. Main components of the skin barrier are located in the outer layers of the epidermis (such as filaggrin), the proteins that form the tight junction (TJ) and components of the innate immune system. Recent data involving skin barrier reveal new information regarding its structure and its role in the mechanic-immunological defense; atopic dermatitis (AD) is an example of a disease related to dysfunctions associated with this complex.

Intranuclear network of 3-5 nm and 8-10 nm fibers in EL-4 lymphoma cells.

While much evidence indicates a high degree of spatial organization in the nucleus, the underlying molecular structures that support it remain poorly characterized. By extracting with high concentrations of RNase A in a modification of the sequential extraction protocol of Penman, we have identified a novel intranuclear network in the mouse lymphoma cell line, EL-4. Micrographs of embedment-free sections of extracted cells reveal anastomosing filaments of two different diameters: 3-5 nm and 8-10 nm. The 3-5-nm filaments are interconnected in many junctions and appear to blend smoothly into each other. The 8-10-nm fibers frequently split into two 3-5-nm filaments. Some 3-5-nm fibers appear to be connected at 90 degrees angles with the 8-10-nm fibers. All junctions are smooth with no apparent junction protein. Flow cytometric analysis of RNase A- (and DNase I-) extracted nuclear matrices indicates that they do not contain significant amounts of protein that react with anti-actin and anti-vimentin monoclonal antibodies. Extraction of EL-4 nuclear matrices with high salt does not reveal 8-10-nm core filaments described after similar treatment of tumor cell lines of cervical and mammary origin. The novel characteristics of the core filaments in EL-4 lymphoma cells may reflect cell-type specificity of the nuclear matrix.

Antibodies against the 59 kDa polypeptide of the N. crassa 8-10 nm filaments immunodetect a 59 kDa polypeptide in specialized rat epithelial cells.

P59Nc is a polypeptide associated with bundles of cytoplasmic and nuclear filamentous structures of 8-10 nm of diameter in Neurospora crassa cells. It is immunologically unrelated to both higher and lower eucaryotic tubulin and actin proteins and is detected weakly by the anti IFA monoclonal antibody. We analyze here the immunological relationship between P59Nc and intermediate filament (IF) mammalian proteins by using anti P59Nc, anti keratin, anti vimentin and anti IFA antibodies. Anti P59Nc antibodies detected a 59 kDa polypeptide from rat and bovine tissues which copurifies with polypeptides of the IF family. Neither P59Nc nor the 59 kDa rat polypeptide were recognized by anti keratin or anti vimentin antibodies. Immunostaining of rat tongue sections with anti P59Nc antibodies showed that the 59 kDa rat polypeptide is present in the cortical cytoplasm of suprabasal epithelial cells. The results indicate that P59Nc shares common antigenic determinants with a still uncharacterized 59 kDa polypeptide from mammalian tissues which have extractability and immunological properties similar to those of IF polypeptides and shows a tissular distribution and a cellular localization similar but distinguishable from keratins.