Focal linear elastosis in a patient with joint hypermobility syndrome

Focal linear elastosis (FLE) is a benign skin findingcharacterized by hypertrophic linear plaques withabnormal elastic fibers on histology. We present aunique case in which focal linear elastosis occurredin the setting of joint hypermobility syndrome(JHS). Our patient, a 20-year-old man with a medicalhistory significant for symptoms consistent with JHS,had been followed by the rheumatology clinic formany months. He was referred to the dermatologydepartment for further evaluation of asymptomaticlongitudinal bands on his back that had been presentfor many years. He denied trauma but endorsed ahistory of 'stretch marks.' On examination there werenumerous horizontally oriented, firm, linear, yellowto flesh colored bands, all non-tender to palpation.Punch biopsies were performed of involved anduninvolved skin. Histopathology of normal skinrevealed no significant abnormalities whereasinvolved skin demonstrated broadened collagenbundles in the deep dermis. The elastic fiber stain,Verhoeff-Van Gieson, revealed a gross increase in thenumber of elastic fibers, fragmented fibers, fiberswith "paintbrush" or widened-ends, fibers of varyingthickness, and clumped fibers. This combination ofhistopathologic and clinical features was consistent with FLE.

Absence of TGFbeta signaling in embryonic vascular smooth muscle leads to reduced lysyl oxidase expression, impaired elastogenesis, and aneurysm

To address the requirement for TGFbeta signaling in the formation and maintenance of the vascular matrix, we employed lineage-specific mutation of the type II TGFbeta receptor gene (Tgfbr2) in vascular smooth muscle precursors in mice. In both neural crest- and mesoderm-derived smooth muscle, absence of TGFbeta receptor function resulted in a poorly organized vascular elastic matrix in late-stage embryos which was prone to dilation and aneurysm. This defect represents a failure to initiate formation of the elastic matrix, rather than a failure to maintain a preexisting matrix. In mutant tissue, lysyl oxidase expression was substantially reduced, which may contribute to the observed pathology.

Targeted disruption of fibulin-4 abolishes elastogenesis and causes perinatal lethality in mice

Elastic fibers provide tissues with elasticity which is critical to the function of arteries, lungs, skin, and other dynamic organs. Loss of elasticity is a major contributing factor in aging and diseases. However, the mechanism of elastic fiber development and assembly is poorly understood. Here, we show that lack of fibulin-4, an extracellular matrix molecule, abolishes elastogenesis. fibulin-4-/- mice generated by gene targeting exhibited severe lung and vascular defects including emphysema, artery tortuosity, irregularity, aneurysm, rupture, and resulting hemorrhages. All the homozygous mice died perinatally. The earliest abnormality noted was a uniformly narrowing of the descending aorta in fibulin-4-/- embryos at embryonic day 12.5 (E12.5). Aorta tortuosity and irregularity became noticeable at E15.5. Histological analysis demonstrated that fibulin-4-/- mice do not develop intact elastic fibers but contain irregular elastin aggregates. Electron microscopy revealed that the elastin aggregates are highly unusual in that they contain evenly distributed rod-like filaments, in contrast to the amorphous appearance of normal elastic fibers. Desmosine analysis indicated that elastin cross-links in fibulin-4-/- tissues were largely diminished. However, expression of tropoelastin or lysyl oxidase mRNA was unaffected in fibulin-4-/- mice. In addition, fibulin-4 strongly interacts with tropoelastin and colocalizes with elastic fibers in culture. These results demonstrate that fibulin-4 plays an irreplaceable role in elastogenesis.

EMILIN-1 deficiency induces elastogenesis and vascular cell defects

EMILINs constitute a family of genes of the extracellular matrix with high structural similarity. Four genes have been identified so far in human and mouse. To gain insight into the function of this gene family, EMILIN-1 has been inactivated in the mouse by gene targeting. The homozygous animals were fertile and did not show obvious abnormalities. However, histological and ultrastructural examination revealed alterations of elastic fibers in aorta and skin. Formation of elastic fibers by mutant embryonic fibroblasts in culture was also abnormal. Additional alterations were observed in cell morphology and anchorage of endothelial and smooth muscle cells to elastic lamellae. Considering that EMILIN-1 is adhesive for cells and that the protein binds to elastin and fibulin-5, EMILIN-1 may regulate elastogenesis and vascular cell maintenance by stabilizing molecular interactions between elastic fiber components and by endowing elastic fibers with specific cell adhesion properties.

Etiology of patent ductus arteriosus in dogs

Patent ductus arteriosus (PDA) is the most common congenital heart disease in dogs and usually causes heart failure and death unless corrected at a young age. Previous histologic studies in a line of dogs derived from Miniature Poodles with hereditary PDA identified varying degrees of hypoplasia and asymmetry of ductus-specific smooth muscle and the presence of aortalike elastic tissue in the ductus wall sufficient to cause patency. To determine if similar structural abnormalities cause PDA in other dogs, serial-section, 3-dimensional histology of ductal architecture was studied in 8 non-Poodle purebred dogs with PDA with no immediate family history of PDA. Morphologic abnormalities were observed in 7 of 8 dogs with PDA and essentially were the same as those in dogs known to have a hereditary form of PDA. These findings suggest that apparently sporadic PDA in these breeds is caused by a genetic defect in the structure of the ductus arteriosus that is similar or identical to that in the Poodle. The relatives of dogs with PDA, particularly parents, offspring, and siblings, should be screened for evidence of PDA. Dogs with PDA should not be used for breeding, regardless of breed.

Abnormality of vascular elastic fibers in the macular mouse and a patient with Menkes' disease: ultrastructural and immunohistochemical study

The macular mouse is a mutant mouse with the same gene abnormality as that of Menkes' disease, and it exhibits symptoms and abnormalities similar to those of Menkes' disease. In an electron microscopic study, we examined morphological changes in the internal elastic lamina (IEL) of the elastic arteries (EA) and the muscular arteries (MA) in a patient with Menkes' disease and in the macular mouse, an animal model of this disease. The IEL of the EA was significantly thinner in the macular mouse than that in controls, but the IEL of the MA in the macular mouse was significantly thicker than that of the controls. These contrary results for the thickness of the IEL in the MA and the EA in this animal model of Menkes' disease may reflect differences in the anatomical and pathophysiological properties of the two types of vessels.

Spontaneous elastic tissue lesions in the rat abdominal aorta, a genetically determined phenotype

In this study, phenotypic expression of spontaneous elastic laminae defects within the rat abdominal aorta was examined. Lesions in Brown Norway (BN) rats were compared with those of New Zealand genetically hypertensive (GH) rats. BN and GH rats were cross-bred to determine the phenotypic expression of these lesions in successive F(1) and F(2) generations. Lesions were assessed by distribution, number and a semiquantitative index of severity. All BN aortae contained numerous elastic tissue defects. In comparison, GH aortae contained only occasional elastic tissue lesions. F(1) aortae contained lesions in numbers similar to those of the parental BN strain; however, F(1) lesions were of significantly greater severity. Within the F(2) generation, a wide range in both lesion numbers and severity indices was observed, with approximately a quarter of animals having lesion numbers analogous to the GH parental strain. In conclusion, this study indicates that the spontaneous elastic tissue lesions observed within BN rats are consistent with an autosomal dominant, possibly single gene, effect. Moreover, epistatic effects, derived from the GH strain, may influence the severity of these lesions. The gene(s) responsible may be important in the development of conditions such as arteriosclerosis and aneurysms in humans.

Skin elastic fibers in Williams syndrome

The elastin gene is consistently deleted in Williams syndrome and as this protein represents the major component of the elastic fibers of the dermis, we sought to investigate skin elastic fibers in Williams syndrome as a key to unraveling extracellular matrix disorganization in this condition. Both morphometric parameters analyzed by using automated image analysis and immunofluorescence labeling with monoclonal antibodies against elastin and fibrillin 1 showed a disorganized pre-elastic (oxytalan and elaunin) and mature elastic fibers in the dermis of 10 Williams syndrome patients compared with five healthy children and one patient with isolated supravalvular aortic stenosis. Skin biopsies in Williams syndrome patients provide a simple mean to elucidate extracellular matrix anomalies. Hopefully, this method could give clues to the understanding of the elastic network anomalies in this condition and even to the consequences of these latter on elasticity and resilience of other tissues such as the arterial tree.

Increased expression of gelatinases A and B by skin explants from patients with anetoderma

The extent of alterations to the elastic fibre network in lesional skin areas of three patients with anetoderma was assessed by quantitative image analysis of tissue sections and compared with morphometric parameters from unaffected sites of the same individuals. In the anetodermic skins pre-elastic fibres were undetectable or extremely rare: the volume fraction (Vv%) occupied by these pre-elastic fibres was 0-0.3%, while in unaffected skins the Vv% occupied by pre-elastic fibres was 0.5-0.8%. A nearly complete absence of dermal elastic fibres in lesional skins from the three patients was evidenced (Vv% = 0.2-0.3%). Organ cultures were performed using explants from skin with or without anetodermic lesions to quantify the expressions of elastase-type proteinases. All tissues from anetodermic lesions expressed proforms of gelatinases A and B and the activated form of gelatinase A; their levels increased with the culture time. In comparison, enzymatic activities on oligopeptide substrates specific for leucocyte elastase and fibroblast plasma membrane-associated metalloelastase were not detected in the conditioned media of any explants at any time of culture from 1 to 5 days. Increased production of progelatinases A and B and activation of progelatinase A could be mainly responsible for the degradation of skin elastic fibres demonstrated in anetodermic skins.

Michelin tire syndrome: a congenital disorder of elastic fibre formation?

We describe a 15-month-old girl with Michelin tyre syndrome. She had hirsuties and marked skin folds. Histological examination showed fragmented elastic fibres in addition to smooth muscle hamartoma. On electron microscopy, decreased deposition of elastin was observed. We speculate that elastic fibre abnormalities may account for the characteristic skin changes in the Michelin tyre syndrome.

Abnormalities in elastic fibers and other connective-tissue components of floppy mitral valve

Histologic, immunohistochemical, and ultrastructural studies were performed on 12 floppy mitral valves, 4 mitral valves showing focal myxomatous changes without prolapse, and 3 normal mitral valves. All floppy mitral valves were thickened by deposits of proteoglycans and also showed diverse structural abnormalities in collagen and elastic fibers. From these observations we conclude that (1) the structure of all major components of connective tissue in floppy mitral valves is abnormal; (2) alterations in collagen and accumulations of proteoglycans are nonspecific changes that may be caused by the abnormal mechanical forces to which floppy mitral valves are subjected because of their excessively large surface area; (3) the presence of excessive amounts of proteoglycans may interfere with the normal assembly of collagen and elastic fibers; (4) abnormalities of elastic fibers resemble those in other conditions characterized by structural dilatation or tissue expansion; and (5) alterations in elastin could result from defective formation, increased degradation, or both.

Syndrome of congenital cutis laxa with ligamentous laxity and delayed development: report of a brother and sister from Turkey

Congenital cutis laxa with ligamentous laxity and delayed development has recently been defined as a distinct entity of autosomal recessive inheritance. Here we report on 2 new cases of this syndrome. With severe manifestations in the male, X-linked dominant inheritance is discussed. Results of ultrastructural studies of skin and biochemical studies are reported.