The present study showed that metalloproteinases, particularly MMP-2, MMP-9, MMP-1, and MMP-13, are involved in the gingival extracellular matrix degradation during periodontitis.

Computed morphometric analysis of elastic skin fibres in patients with cutis laxa, anetoderma, Williams-Beuren syndrome, pseudoxanthoma elasticum (PXE), and Buschke-Ollendorff syndrome, all clinically ascertained, was performed and compared with data obtained from healthy individuals of the same age. The diameters, area fractions (AA%) and volume fractions (VV%) occupied by pre-elastic fibres and dermal elastic fibres were determined. Irrespective of age the diameter of dermal elastic fibres followed a Gaussian distribution for all groups studied. These diameters were taken into consideration for VV% determinations. Compared with data from skin of healthy subjects of similar age range, VV% of pre-elastic fibres was significantly decreased in patients with cutis laxa, anetoderma, Williams-Beuren syndrome, and PXE and undetectable in Buschke-Ollendorff patients. VV% of dermal elastic fibres was four- to fivefold increased in Buschke-Ollendorff syndrome, two- to threefold increased in PXE skin, four- to fivefold decreased in cutis laxa and anetoderma skin and about twofold decreased in Williams-Beuren skin. The diameter of oxytalan fibres was decreased in anetoderma and Williams-Beuren syndrome while oxytalan fibre diameter was unchanged in PXE and cutis laxa. The diameter of dermal elastic fibres was increased in PXE and Buschke-Ollendorff syndrome, but was decreased in anetoderma and Williams-Beuren syndrome and unchanged in cutis laxa. We demonstrated that cutis laxa, anetoderma, Williams-Beuren syndrome, PXE, and Buschke-Ollendorff syndrome could be easily differentiated by morphometric analysis of elastic skin fibres. Thus we propose that morphometric analyses together with skin biopsies are a valuable tool for distinguishing between inherited and/or acquired skin diseases known to display alterations of elastic fibres.

A number of COL7A1 mutations have now been reported in recessive dystrophic epidermolysis bullosa patients, and the analysis of phenotype-genotype correlations showed evidence for interfamilial and intrafamilial phenotypic variability, occurring for the same mutation. Collagenase and stromelysin activities have been found to be overexpressed in skin cultures of some recessive dystrophic epidermolysis bullosa patients, and tissue destruction in the disease process might result from an imbalance of metalloproteinases (MMP) over tissueinhibitor of metalloproteinases (TIMP). So we suspected that the phenotypic variability for the same mutation could be linked to other genetic or environmental factors, as a particular balance between MMP and TIMP. Organ cultures were performed using explants from the skin of three patients from the same family with recessive dystrophic epidermolysis bullosa to reveal and quantify the expression of MMP-1 (collagenase 1), MMP-2 and MMP-9 (gelatinases A and B), MMP-3 (stromelysin 1), TIMP-1, and TIMP-2, and to compare the results with those obtained with two human control skins, with the same experimental conditions. Increased amounts of all metalloproteinases investigated were observed in the skin of the three recessive dystrophic epidermolysis bullosa affected sibling brothers, both in lesioned and in apparently nonlesioned skin, compared with controls. The amounts of MMP-1, MMP-2, MMP-3, and MMP-9 increased particularly in the skin of the more clinically affected patient. Furthermore for this patient we evidenced higher amounts of MMP-1 and also a lower TIMP-1 amount in his unlesioned and lesioned skin compared with the other two affected patients and with healthy control donors. So we can suspect that recessive dystrophic epidermolysis bullosa phenotypic variability could be related to patients' collagenase activity heterogeneity, linked to imbalance between MMP-1 and TIMP-1.

The amount of elastic fibers from lesional and healthy skin areas of five patients with anetoderma was determined by automated image analysis. Dermal elastic fibers were almost completely absent in anetodermic skin and preelastic fibers were undetectable or extremely rare. Organ cultures were performed using explants from affected and unaffected skin areas of the same patient. We identified and quantified proteases in the culture media of explants: MMP-1 (collagenase 1), MMP-2 and MMP-9 (gelatinases A and B), MMP-3 (stromelysin 1), MMP-7 (matrilysin 1), and tissue inhibitors of metalloproteinases, TIMP-1 and TIMP-2. The data were compared with those of two healthy donors. For the five samples of anetodermic skin, MMP-1 levels were significantly higher compared with the uninvolved cultures and the two healthy samples. A significant increase of TIMP-1 expression was also observed in the affected cultures. We demonstrated a significant increase in the production of gelatinase A in lesional skin when compared with nonlesional skin and healthy donor samples. We found no significant production of TIMP-2 in the five samples of anetodermic skin compared with the samples from the two healthy donors. There was a significant decrease in TIMP-2 expression in the five nonlesional samples compared with the control samples. These data are in favor of an altered balance in anetodermic patients between MMP-2 and TIMP-2. Levels of MMP-9, MMP-3, and MMP-7 were significantly higher in the culture-conditioned media of the anetodermic skin samples than the nonlesional skin cultures. Because MMP-3, MMP-7, MMP-9 are known to degrade elastin, and MMP-3 can activate the latent forms of MMP-7 and MMP-9, we propose that these metalloproteinases also participate in the degradation of elastic fibers in anetodermic skin.