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W C Parks

Publications and source records attributed to W C Parks.

At least 73 records · Page 4Linked to original sources
PubMed1995

Glucocorticoids upregulate tropoelastin expression during late stages of fetal lung development.

The production of elastin, an essential extracellular matrix protein of terminal airway interstitium, occurs mostly during early development. Because glucocorticoids influence airway maturation, we studied the effect of dexamethasone (Dex) on tropoelastin expression during fetal lung development. Timed-pregnant rats were treated with Dex (1 mg/kg daily), and fetal lungs were collected 3 days later at 17, 19, and 21 days of gestation. Dex treatment resulted in about a threefold increase in tropoelastin mRNA levels at 19 days concomitant with accelerated airway development. By in situ hybridization, Dex treatment increased the number of tropoelastin-expressing cells and the level of tropoelastin mRNA per cell. In organ culture, Dex increased lung tropoelastin expression and augmented cortisol stimulation of tropoelastin expression. In fetal pulmonary artery smooth muscle cells, 10(-8) M Dex upregulated tropoelastin mRNA expression and increased tropoelastin promoter-chloramphenicol acetyl transferase activity in transient transfections. These data indicate that pharmacologically administered glucocorticoids transcriptionally upregulate fetal lung tropoelastin expression and suggest that steroid hormones may be important regulators of elastin production in vivo.

Animals↗
PubMed1995

Production and localization of 92-kilodalton gelatinase in abdominal aortic aneurysms. An elastolytic metalloproteinase expressed by aneurysm-infiltrating macrophages.

Abdominal aortic aneurysms (AAA) are characterized by disruption and degradation of the elastic media, yet the elastolytic proteinases involved and their cellular sources are undefined. We examined if 92-kD gelatinase, an elastolytic matrix metalloproteinase, participates in the pathobiology of AAA. Gelatin zymography of conditioned medium from normal, atheroocclusive disease (AOD), or AAA tissues in organ culture showed that all tissues produced 72-kD gelatinase. AOD and AAA cultures also secreted 92-kD gelatinase, but significantly more enzyme was released from AAA tissues. ELISA confirmed that AAA tissues released approximately 2-fold more 92-kD gelatinase than AOD tissue and approximately 10-fold more than normal aorta. Phorbol ester induced a 5.3-fold increase in 92-kD gelatinase secretion by normal aorta and AOD and an 11.5-fold increase by AAA. By immunohistochemistry, 92-kD gelatinase was not detected in normal aorta and was only occasionally seen within the neointimal lesions of AOD tissue. In all AAA specimens, however, 92-kD gelatinase was readily localized to numerous macrophages in the media and at the adventitial-medial junction. The expression of 92-kD gelatinase mRNA by aneurysm-infiltrating macrophages was confirmed by in situ hybridization. These results demonstrate that diseased aortic tissues secrete greater amounts of gelatinolytic activity than normal aorta primarily due to increased production of 92-kD gelatinase. In addition, the localization of 92-kD gelatinase to macrophages in the damaged wall of aneurysmal aortas suggests that chronic release of this elastolytic metalloproteinase contributes to extracellular matrix degradation in AAA.

Aorta↗
PubMed1995

Fibrillin-1 and fibrillin-2 show temporal and tissue-specific regulation of expression in developing elastic tissues.

The recent characterization of multiple fibrillin genes raises the question of whether each of the fibrillin proteins is a component of elastic fiber microfibrils and whether their expression during development of elastic tissues is consistent with a function associated with elastogenesis. To address these possibilities, the expression of fibrillin-1 and fibrillin-2 was compared with expression of MAGP and tropoelastin in two elastogenic tissues that undergo different developmental programs. For both fibrillins, the greatest increase in expression occurred during the last half of fetal development when elastin production is highest. In fetal bovine nuchal ligament, mRNA levels for fibrillin-1 and fibrillin-2 increased approximately threefold during this period, whereas tropoelastin increased 20-fold. Although the relative increase in expression of both fibrillins was equivalent, the basal level of fibrillin-1 expression was greater than fibrillin-2. In developing bovine aorta, fibrillin mRNA levels again paralleled tropoelastin expression although, compared to ligament, elastin synthesis began at an earlier fetal age in this tissue. Furthermore, the relative increase in aortic fibrillin-2 expression was greater than that for fibrillin-1 and the ratio of fibrillin-2 to fibrillin-1 was higher than in the ligament. In contrast to the fibrillins, MAGP expression in nuchal ligament and aorta remained at a constant high level throughout the fetal period. Indirect immunofluorescent staining and immunoelectron microscopy localized both fibrillins as well as MAGP to elastic fiber microfibrils in these developing tissues. The coordinate upregulation of fibrillin-1 and fibrillin-2 expression with the onset of tropoelastin production is consistent with a role in elastic fiber assembly. Our findings also suggest temporal and tissue-specific regulation for the fibrillins during development.

Age Factors↗
PubMed1994

Collagen-stimulated induction of keratinocyte collagenase is mediated via tyrosine kinase and protein kinase C activities.

We have previously shown that during wound healing migrating keratinocytes, which are in contact with the dermal matrix, express interstitial collagenase, whereas basal epidermal cells, which reside on an intact basement membrane, do not. Duplicating this in vivo pattern, collagenase production was induced in primary human keratinocytes grown on native type I collagen, but only background levels of enzyme were detected in cells cultured on denatured type I collagen or on Matrigel. Using genistein, herbimycin A, and sodium orthovanadate, we show that tyrosine kinase activity was required for collagen-mediated induction of keratinocyte collagenase. Similarly, collagenase steady-state mRNA levels and the activity of a transfected human collagenase-promoter CAT construct were inhibited by genistein and enhanced by orthovanadate. Staurosporine and H-7 also blocked collagenase production, indicating that protein kinase C activity was also required for collagen-mediated induction of keratinocyte collagenase. All inhibitory effects were dose-dependent, and no compound significantly affected total protein synthesis. Furthermore, both tyrosine kinase and protein kinase C inhibitors blocked phorbol ester-mediated induction of collagenase, but only protein kinase C antagonists abrogated phorbol ester-mediated induction of c-fos mRNA. These data suggest that similar signal transduction pathways are used by various agonists to mediate the stimulation of interstitial collagenase production.

Alkaloids↗
PubMed1994

Increased mesenchymal cell density accompanies induction of tropoelastin expression in developing elastic tissue.

We studied the differentiation of elastin-producing fetal bovine chondrocytes to understand the regulatory processes associated with induction of elastin expression. Analysis of auricular elastic cartilage development in vivo indicated that differentiation of the prechondrogenic blastema to an elastogenic phenotype was preceded and accompanied by condensation of the mesenchymal cells. In addition, induction of elastin production was temporally and spatially linked to expression of type II collagen and proteoglycans. We assessed the influence of cell density on the induction of tropoelastin expression in pre-elastogenic cells from developing ear buds. Tropoelastin expression was induced in prechondrogenic mesenchymal cells only if the cells were maintained at a high cellular density. In addition, high density culture upregulated tropoelastin expression in fully differentiated chondrocytes. Together these data suggest that high cell density facilitates cell:cell interactions that affect cell proliferation and influence tropoelastin expression.

Animals↗
PubMed1994

Uncoordinate regulation of collagenase, stromelysin, and tissue inhibitor of metalloproteinases genes by prostaglandin E2: selective enhancement of collagenase gene expression in human dermal fibroblasts in culture.

The degradative effects of interleukin-1 (IL-1) on the extracellular matrix of connective tissue are mediated primarily by metalloproteinases and prostaglandins. Clinical observations suggest that these effects can be prevented, to some extent, by the use of non-steroidal anti-inflammatory drugs. We have examined the role of prostaglandin E2 (PGE2) in IL-1-induced gene expression by human skin fibroblasts in culture. Incubation of confluent fibroblast cultures with varying concentrations (0.01-1.0 microgram/ml) of PGE2 led to a dose-dependent elevation of collagenase mRNA steady-state levels, the promoter activity, and the secretion of the protein, whereas relatively little effect was observed on stromelysin and TIMP gene expression. Exogenous PGE2 had no additive or synergistic effect with IL-1 on collagenase gene expression. Furthermore, commonly used non-steroidal anti-inflammatory drugs (indomethacin, acetyl salicylic acid and ibuprofen), at doses which block prostaglandin synthesis in cultured fibroblasts, failed to counteract IL-1-induced collagenase and stromelysin gene expression, nor did they affect TIMP expression. Although the effects of PGE2 did not potentiate those of IL-1 on collagenase gene expression in vitro, one could speculate that massive production of PGE2 by connective tissue cells in vivo in response to inflammatory mediators such as IL-1 or tumor necrosis factor-alpha, could lead to sustained expression of collagenase in connective tissue cells after clearance of the growth factors.

Cells, Cultured↗
PubMed1994

Conversion to an elastogenic phenotype by fetal hyaline chondrocytes is accompanied by altered expression of elastin-related macromolecules.

Elastic fibers are produced during fetal and neonatal periods, and by maturity elastin expression has ceased. Fetal bovine hyaline chondrocytes acquired an elastogenic phenotype within 24 hr after isolation from the tissue, even though the tissue does not produce elastic fibers or tropoelastin mRNA in vivo. By multiple parameters, hyaline chondrocytes produced elastic fibers that were indistinguishable from those made by elastic chondrocytes derived from fetal elastic ear cartilage. The levels of tropoelastin mRNA, secreted protein, and elastic fiber crosslinks as well as the immunostaining and ultrastructural appearance of elastic fibers produced by cultured hyaline chondrocytes were similar if not identical to those of cultured elastic chondrocytes. We also examined the expression of elastin-associated microfibrillar proteins. In intact hyaline cartilage, we did not detect mRNA for fibrillin 5 mRNA and saw only a relatively weak signal for fibrillin 15 mRNA. These microfibrillar products were expressed with tropoelastin in cultured hyaline chondrocytes as well as in intact elastic cartilage and cultured elastic chondrocytes, suggesting that fibrillin 5 and fibrillin 15 are required for elastic fiber formation. In contrast, the levels of microfibrillar-associated glycoprotein mRNA were decreased in both cell types relative to the high expression seen in vivo. These data indicate that conversion to the elastin phenotype includes induction or modulation of all known components of elastic fibers.

Animals↗
PubMed1994

The regulation of collagen in fetal skin wounds: mRNA localization and analysis.

The deposition of collagen in fetal skin wounds has been shown in several animal models. The authors used a radiolabeled RNA antisense probe, complementary to the mRNA for the alpha-1 chain of human procollagen type I, to assess regulation of this collagen species in fetal and adult rabbit wounds. Dorsal skin wounds were placed on fetal and maternal animals at the beginning of the third trimester, and were harvested 3, 5, and 7 days later. In situ RNA/RNA hybridization was performed on suitable specimens, and morphometric analysis was carried out with a computerized LECO image analyzer. Fetal wounds exhibited an inflow of mesenchymal cells that produced collagen type I at levels higher than the surrounding tissue; this activity was highest on days 3 and 5 after wounding. Adult wounds had increased fibroblast presence by day 7, producing collagen type I at levels higher than those of adjacent unwounded tissue. Morphometric analysis of the signal produced by in situ hybridization and of the number of cells producing the signal in a given field showed that fetal wounds appear to produce collagen type I by an increase in the number of cells in the area of the wound--not by induction of the gene for procollagen type I. In contrast, adult wounds had both fibroblast migration and induction of procollagen type I mRNA synthesis. These findings imply multilevel regulation of collagen production in the adult and posttranslational regulation in the fetus.

Animals↗
PubMed1994

Persistence of the fetal pattern of tropoelastin gene expression in severe neonatal bovine pulmonary hypertension.

Neonatal hypoxic pulmonary hypertension causes increases and spatial changes in tropoelastin expression in pulmonary arteries. However, it is not clear if this is due to recruitment of quiescent smooth muscle cells (SMC) into an elastin-producing phenotype or persistence of the fetal pattern of tropoelastin gene expression. We evaluated the distribution and relative concentration of tropoelastin mRNA in intralobar pulmonary arteries from late gestation fetuses and in animals exposed to hypobaric hypoxia (430 mmHg) from birth for 1, 3, 7, or 14 d, as well as in age-matched and adult room air-breathing controls. In situ hybridization demonstrated that tropoelastin mRNA was distributed throughout the entire radius of the pulmonary vessel wall in the fetus and newborn calf. By 15 d of age, only cells in the inner third of the media expressed tropoelastin mRNA, and by adulthood no tropoelastin mRNA was detected in the vessel wall. These findings demonstrated that tropoelastin expression shuts off in a spatially specific pattern, moving from the abluminal to the luminal side of the medial in the neonatal pulmonary artery when pressures and resistance are falling. In the aorta of 15-d-old calves, tropoelastin mRNA expression was seen equally throughout the media, indicating tissue-specific regulation of elastin in the neonatal period. In contrast, intralobar pulmonary arteries from calves exposed to hypoxia, which prevented the normal postnatal decline in pulmonary artery pressure, maintained the fetal pattern and levels of tropoelastin mRNA expression at all time points. Thus, rather than causing a recruitment of SMC into an elastin-producing phenotype, neonatal pulmonary hypertension caused a persistence of the fetal pattern of tropoelastin expression in medial SMC. Cell-free translation showed that the same tropoelastin isoforms were made by mRNA from control and hypertensive calves and, unlike the ligamentum nuchae, did not change during the transition from fetal to neonatal life. We conclude that pulmonary hypertension in the neonate perturbs the normal postpartum repression of tropoelastin expression resulting in a persistence of the fetal spacial and isoform patterns of tropoelastin gene expression.

Animals↗
PubMed1994

92-kD gelatinase is produced by eosinophils at the site of blister formation in bullous pemphigoid and cleaves the extracellular domain of recombinant 180-kD bullous pemphigoid autoantigen.

Eosinophils are prominent in bullous pemphigoid (BP), and proteases secreted from these and other inflammatory cells may induce disruption of the basement membrane. We used in situ hybridization and immunohistochemistry to localize the sites of 92-kD gelatinase expression in BP lesions. In all samples (20/20), a strong signal for gelatinase mRNA was detected only in eosinophils and was most pronounced where these cells accumulated at the floor of forming blisters. No other cells were positive for enzyme mRNA. Both eosinophils and neutrophils, however, contained immunoreactive 92-kD gelatinase indicating that active expression occurred only in eosinophils. Degranulated eosinophils were also seen near blisters, and as demonstrated by gelatin zymography, immunoblotting, and ELISA, 92-kD gelatinase protein was prominent in BP blister fluid. No other gelatinolytic activity was specifically detected in BP fluid, and only small amounts of 92-kD gelatinase were present in suction blister fluids. As demonstrated in vitro, 92-kD gelatinase cleaved the extracellular, collagenous domain of recombinant 180-kD BP autoantigen (BP180, BPAG2, HD4, type XVII collagen), a transmembrane molecule of the epidermal hemidesmosome. Our results suggest that production and release 92-kD gelatinase by eosinophils contributes significantly to tissue damage in BP.

Autoantigens↗
PubMed1994

Distinct populations of basal keratinocytes express stromelysin-1 and stromelysin-2 in chronic wounds.

Wound repair involves cell migration and tissue remodeling, and these ordered and regulated processes are facilitated by matrix-degrading proteases. We reported that interstitial collagenase is invariantly expressed by basal keratinocytes at the migrating front of healing epidermis (Saarialho-Kere, U. K., E. S. Chang, H. G. Welgus, and W. C. Parks, 1992. J. Clin. Invest. 90:1952-1957). Because of the limited substrate specificity of collagenase, principally for interstitial fibrillar collagens, other enzymes must also be produced in the wound environment to effectively restructure tissues with a complex matrix composition. Stromelysins-1 and -2 are closely related, yet distinct metalloproteinases, and both can degrade many noncollagenous connective tissue macromolecules. Using in situ hybridization and immunohistochemistry, we found that both stromelysins are produced by distinct populations of keratinocytes in a variety of chronic ulcers. Stromelysin-1 mRNA and protein were detected in basal keratinocytes adjacent to but distal from the wound edge in what probably represents the sites of proliferating epidermis. In contrast, stromelysin-2 mRNA was seen only in basal keratinocytes at the migrating front, in the same epidermal cell population that expresses collagenase. Stromelysin-1-producing keratinocytes resided on the basement membrane, whereas stromelysin-2-producing keratinocytes were in contact with the dermal matrix. Furthermore, stromelysin-1 expression was prominent in dermal fibroblasts, whereas no signal for stromelysin-2 was seen in any dermal cell. These findings demonstrate that stromelysins-1 and -2 are produced by different populations of basal keratinocytes in response to wounding and suggest that these two matrix metalloproteinases serve distinct roles in tissue repair.

Cells, Cultured↗
PubMed1994

Consequences of prolonged inhalation of ozone on F344/N rats: collaborative studies. Part IV: Effects on expression of extracellular matrix genes.

Increased deposition of lung extracellular matrix in terminal airways is associated with chronic ozone exposure. In situ hybridization was used to assess whether long-term ozone exposure causes elevated and continued expression of genes coding for connective tissue proteins. Accessory lobes were removed from the animals exposed to 0, 0.12, 0.5, or 1.0 parts per million (ppm)* ozone for 20 months as part of the National Toxicology Program (NTP)/HEI Collaborative Ozone Project. The lungs were perfused fixed under physiologic pressure and processed for in situ hybridization. Sections were hybridized with 35S-labeled probes for messenger RNA (mRNA) coding for various matrix proteins, including collagen types I and III, elastin, and fibronectin, and for interstitial collagenase, a matrix metalloproteinase. Fetal rat lung was used as a positive control for hybridization. No signal for any mRNA was detected in terminal airway stromal cells of lungs from animals exposed to ozone for 20 months or control animals breathing clean air. In all samples from animals exposed to ozone for 20 months and control animals, only a very weak signal was seen in occasional cells within the interstitial spaces around large airways and blood vessels. In contrast, a strong signal for matrix-related mRNA was detected in fetal lung tissue. These findings indicate that active or enhanced matrix production is turned off in the adult animals used in the ozone studies, suggesting that the increase in matrix deposition results from a transient and early fibrotic response. Indeed, signal for type I procollagen and tropoelastin mRNAs was seen in alveolar septal cells in lungs of rats exposed to ozone for two months. No signal was seen in alveolar cells of age-matched control animals. (These animals, exposed for two months, and age-matched controls were from earlier studies supported by the HEI.) These findings indicate that ozone mediates a transient fibrotic response that results in a sustained increase in lung extracellular matrix. Confirmation of this hypothesis would require additional studies using animals exposed to ozone for shorter times.

Administration, Inhalation↗
PubMed1994

Persistence, re-expression, and induction of pulmonary arterial fibronectin, tropoelastin, and type I procollagen mRNA expression in neonatal hypoxic pulmonary hypertension.

Changes in the structure and function of muscular pulmonary arteries are crucial for normal adaptation to extrauterine life and rapid changes in matrix protein gene expression are likely necessary for this adaptation. We hypothesized that pathological stimuli imposed at the time of birth would alter developmental changes in matrix protein gene expression thereby affecting the normal post-uterine changes in pulmonary hemodynamics. We used in situ hybridization to examine the normal developmental expression of three extracellular matrix protein mRNAs, fibronectin, tropoelastin, and alpha 1 (I) procollagen, in muscular pulmonary arteries of both fetal and neonatal calves and assessed the impact of severe hypoxia-induced pulmonary hypertension on their expression. Morphometric techniques were used to assess whether changes in matrix protein mRNA levels were related to changes in matrix fiber accumulation. Exposure to chronic hypoxia postnatally resulted in the persistence, reexpression, and induction of fibronectin, tropoelastin, and alpha 1 (I) procollagen mRNAs, respectively, in muscular pulmonary arteries. In each case the hybridization signal was localized primarily to the adventitial layer of the vessel. Morphometric analysis showed that the increased hybridization signals seen correlated with an increase in both vascular elastin and collagen fiber volumes in the adventitial layer. We conclude that the change in expression of matrix genes in the pulmonary artery wall during exposure to chronic hypoxia is an important adaptive response to changes in hemodynamic factors and/or oxygen tension. The unchecked increase in matrix protein expression seen likely contributes to the pathological pulmonary arterial structural remodeling and loss of vasoreactivity that occurs during the development of severe neonatal pulmonary hypertension.

Animals↗
PubMed1993

Effects of 20 months of ozone exposure on lung collagen in Fischer 344 rats.

Fischer 344 rats were exposed to filtered air (controls) or to 0.12, 0.5, or 1.0 ppm of ozone for 6 h/day, 5 days/week, for 20 months. We examined lung collagen deposition and metabolism in tissue from these animals to determine whether chronic exposure of rats to ozone causes pulmonary fibrosis. We observed excess stainable collagen in the centriacinar region of lungs from the rats exposed to 0.5 or 1.0 ppm of ozone. Biochemical analysis indicated a slight, yet significant, excess collagen deposition in the female rats exposed to 0.5 or 1.0 ppm of ozone. Collagen in the lungs of the females also contained relatively more hydroxylysine-derived crosslinks than did lung collagen from age-matched control animals. No excess of type I procollagen mRNA could be appreciated by in situ hybridization in lungs of the rats exposed to 1.0 ppm of ozone for 20 months, although this mRNA was detected in occasional alveolar interstitial cells at 2 months of exposure to ozone under the same protocol. These findings indicate that chronic exposure of rats to ozone causes mild, persistent fibrosis. The significance of these observations with regard to human health risks of chronically inhaling ozone at ambient levels in polluted air remains to be determined.

Animals↗
PubMed1993

Distinct mechanisms regulate interstitial collagenase and 92-kDa gelatinase expression in human monocytic-like cells exposed to bacterial endotoxin.

We studied the mechanisms that govern the expression of interstitial collagenase and 92-kDa gelatinase in U937 cells, a human monocyte-like cell line, exposed to bacterial lipopolysaccharide (LPS), a potent inducer of metalloproteinase expression. U937 cells were differentiated by phorbol ester (phorbol 12-myristate 13-acetate (PMA)) and, 24 h later, were exposed to LPS for an additional 24 h. Enzyme-linked immunosorbent assay and Northern hybridization showed that PMA mediated an induction of collagenase and markedly stimulated the low basal levels of 92-kDa gelatinase. Subsequent exposure to LPS substantially increased the production of both enzymes. Nuclear runoff assay demonstrated that PMA regulated collagenase and 92-kDa gelatinase transcription. LPS also stimulated collagenase transcription but did not affect transcription of 92-kDa gelatinase. Consistent with the runoff data, the decay rate of collagenase mRNA did not differ between experimental treatments, but the half-life of gelatinase mRNA increased with exposure to LPS. Furthermore, in situ hybridization showed that 92-kDa gelatinase was expressed by all cells whereas collagenase was produced by a subpopulation of cells in both PMA- and PMA/LPS-exposed cultures, and similar findings were seen with LPS-activated human alveolar macrophages. These data indicate that divergent mechanisms control metalloproteinase expression in phagocytic cells and that enzyme production differs among macrophage subpopulations.

Adult↗
PubMed1993

Molecular mechanisms regulating the production of collagenase and TIMP in U937 cells: evidence for involvement of delayed transcriptional activation and enhanced mRNA stability.

We have used the human promonocyte-like U937 cell line as a model to study the regulation of interstitial collagenase and tissue inhibitor of metalloproteinases (TIMP) during mononuclear phagocyte development. Our results show that differentiation of U937 cells with exposure to 12-O-tetradecanoylphorbol 13-acetate (TPA) induces a temporally delayed (16-24 h) but marked increase in the biosynthesis and secretion of interstitial collagenase and TIMP. Similarly, steady-state mRNA levels for both proteins rose dramatically during the period of exposure, but again after considerable time delay (12-16 h). For interstitial collagenase, induction was transcriptionally regulated as demonstrated by nuclear run-on experiments, and required the synthesis of proteins as indicated by cycloheximide treatment. However, transcriptional activation of collagenase was never observed prior to 10-12 h; since c-fos is rapidly induced in U937 cells and largely disappears by 2 h (Mitchell et al., 1985), our data strongly suggest that collagenase induction in this system cannot be explained simply or entirely by an AP-1-dependent mechanism. Although TIMP steady-state mRNA levels also increased substantially with cellular differentiation, no transcription was detected by run-on experiments. However, TPA exposure markedly prolonged the half-life of TIMP mRNA from 4 h to > 20 h. While cycloheximide treatment completely blocked TPA-mediated induction of collagenase mRNA, it only marginally interfered with simultaneously induced TIMP mRNA levels. Our results demonstrate that differentiation of U937 monocytic cells is accompanied by markedly enhanced production of both interstitial collagenase and TIMP. However, there are multiple, and perhaps differing, molecular mechanisms regulating these responses.

Adult↗
PubMed1993

Expression of interstitial collagenase, 92-kDa gelatinase, and tissue inhibitor of metalloproteinases-1 in granuloma annulare and necrobiosis lipoidica diabeticorum.

Granuloma annular (GA) and necrobiosis lipoidica diabeticorum (NLD) are disorders characterized by granulomatous inflammation and degenerative changes in collagen and elastic fibers. Because these disorders have often been described as being associated with altered extracellular matrix deposition, we studied the in situ expression of interstitial collagenase, 92-kDa gelatinase, and tissue inhibitor of metalloproteinases (TIMP)-1. Twelve lesions each of GA and NLD of different histopathologic types and durations were examined. Interstitial collagenase mRNA was seen in histiocyte-like cells in one-third of the cases of both diseases, typically in younger lesions. In GA, collagenase mRNA was only detected in lesions of the palisading type. Signal for 92-kDa gelatinase mRNA was observed in eosinophils, which were present in low numbers in five of 12 GA and three of 12 NLD samples. The signal for this enzyme and the presence of eosinophils did not correlate with the age of lesion. TIMP-1 mRNA was consistently expressed by histiocyte-like cells in both disorders. In GA, TIMP-1 mRNA was detected at the outer edge of the palisading granulomas, but in NLD, inhibitor expression was seen in the perivascular and periadnexal accumulation of inflammatory cells. Our data indicate that collagenase and TIMP are expressed early in these disorders and that these proteins may contribute to stromal remodeling associated with necrobiotic lesions. Our results further indicate that the localization of TIMP-1 production may provide a distinction between the two disorders, whereas metalloproteinase expression is not sufficiently specific to aid in the differential diagnosis of GA and NLD.

Adult↗