Anti-elastofibril monoclonal antibody NKH-1: production and application

Microfibrillar elements of the dermal matrix

Connective tissue microfibrils are key structural elements of the dermal matrix which play major roles in establishing and maintaining the structural and mechanical integrity of this complex tissue. Type VI collagen microfibrils form extensive microfibrillar networks which intercalate between the major collagen fibrils and are juxtaposed to cellular basement membranes, blood vessels and other interstitial structures. Fibrillin microfibrils define the continuous elastic network of skin, and are present in dermis as microfibril bundles devoid of measureable elastin extending from the dermal-epithelial junction and as components of the thick elastic fibres present in the deep reticular dermis. Electron microscopic analyses have revealed both classes of microfibrils to have complex ultrastructures. The ability to isolate intact native microfibrils from skin has enabled a combination of high resolution and biochemical techniques to be applied to elucidate their structure:function relationships. These approaches have generated new information about their molecular organisation and physiological interactions in health and disease.

Fibrillin-containing microfibrils: structure and function in health and disease

Fibrillin-containing microfibrils are a unique class of connective tissue macromolecules whose critical contribution to the establishment and maintenance of diverse extracellular matrices was underlined by the recent linkage of their principal structural component fibrillin to Marfan syndrome, a heritable disorder with pleiotrophic connective tissue manifestations. The complexity of the structure: function relationships of these macromolecules was highlighted by the recent elucidation of the primary structure of fibrillin and characterisation of fibrillin mutations in Marfan patients. This review examines current understanding of the expression and assembly of fibrillin and describes new approaches which are now being applied to elucidate the many outstanding structural, organisational and functional aspects of the fibrillin-containing microfibrils.

Biphasic amyloidosis arising from friction melanosis

A 40-year-old woman who had used nylon towels in the bath for about 10 years noticed hyperpigmentation on the prominent regions over the bones of the trunk and extremities. She also developed lichenoid papules with itching on her back. Histologically, both the pigmented and the papular lesions had amyloid deposits beneath the epidermis. In this case it is presumed that the papular lesions with amyloid (lichen amyloidosus) developed initially from friction melanosis which became macular pigmented lesion (macular amyloidosis). The etiologic factor of these sequential pathologic changes is considered to be repeated scrubbing with nylon towels.

Fibrillin immunoreactive fibers constitute a unique network in the human dermis: immunohistochemical comparison of the distributions of fibrillin, vitronectin, amyloid P component, and orcein stainable structures in normal skin and elastosis

Fibrillin, a 350-kD glycoprotein, was recently localized to elastin-associated 10 nm microfibrils. Here, the distribution of fibrillin immunoreactivity was determined in normal skin in individuals of different ages and in lesions of solar elastosis or anetoderma. It was compared with the distribution of orcein-stainable fibers and with the immunoreactivities of vitronectin and amyloid P component. These glycoproteins are known to occur in conjunction with the orcein-stainable elastic fibers in adults, but not in the young. Fibrillin immunoreactivity was associated with orcein-stainable fibers in normal skin of both adults and the young. In addition, the fibrillin immunoreactive fiber network comprised fine fibers that were unstainable by orcein, anti-vitronectin, or anti-amyloid P component. Such fine fibers were especially abundant close to the dermal-epidermal junction zone. Immunoreactivities of anti-vitronectin and anti-amyloid P component were not always associated with fibrillin immunoreactivity but were consistently found to co-localize with orcein-stainable fibers in adults. This suggests vitronectin and amyloid P component to be associated with the amorphous elastin rather than with the microfibrils, although alternative interpretations are possible. In elastotic lesions, fibrillin immunoreactivity was generally fainter than that obtained using anti-vitronectin or anti-amyloid P component. In contrast, an extensive network of dermal fibers stained by anti-fibrillin, but not by anti-amyloid P component, anti-vitronectin, or orcein, was seen in an anetoderma lesion. In conclusion, fibrillin immunoreactivity is associated with a unique dermal network, which ultrastructurally is composed of microfibrils. These fibers are proposed to have an important structural and functional role in anchoring the dermal elastic fibers in the extracellular matrix and to the lamina densa.

Juvenile colloid milium. Immunohistochemical and ultrastructural studies

A 7-year-old Italian girl with juvenile colloid milium was studied with histological, immunohistochemical, and electron microscopic methods. This patient had a well-documented history of severe sunburn and developed the lesions on the face shortly afterward. Numerous apoptotic keratinocytes were observed in the lower epidermis. These cells began their degeneration with filamentous whorl formation (or filamentous degeneration) of tonofilaments. In the papillary dermis the colloid substance was resolved by the electron microscopy into either wavy, thin filaments derived from the epidermal keratinocytes or typical amyloid filaments. Many desmosomes and gap junctions were found in the colloid substance. Polyclonal antikeratin antibody (DAKO) was positive in the colloid substance, particularly in the parts close to the epidermis. These findings suggested that juvenile colloid milium is different from adult colloid milium despite clinical similarities and that the former belongs to the group of actinic amyloid K, i.e. amyloidoses due to actinic degeneration of keratinocyte and its keratin.

Roles of immunoglobulins in amyloidogenesis in cutaneous nodular amyloidosis

Immunoglobulin heavy and light chains and C3 were detected on amyloid deposits in cutaneous nodular amyloidosis (NA) by a direct immunofluorescence method. These immunoglobulin chains and C3 could be removed except lambda (lambda) light chain after treating sections with 0.05% Tween 20 solution, 0.1 M glycine buffer pH 7.4 or 0.5% Triton X solution. Lambda light chain was detected consistently after these treatments. Amyloid filaments were not altered with these treatments. Immunoelectron microscopy demonstrated persistent antigenicity of lambda light chain on amyloid filaments. It was suggested that lambda light chain is an inherent component of amyloid filaments in NA, whereas other chains and complement represent nonessential absorption on amyloid material.