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The article investigates the impact on the submandibular gland morphology in rats of increased intraluminal pressure. An experiment is performed and results are discussed. Both a widening of the striated and granular duct lumina and unusual enlargement of the intercalated duct lumina were produced by increased pressure. Additional symptoms at even greater pressure included enlarging of the desmosomes. Both the interlobular ducts and main excretory duct, on the other hand, did not appear to be affected.

This study investigates the effects of interleukin (IL)-1 beta on proteoglycan metabolism by fibroblasts surrounded by endogenous extracellular matrix. In both three-dimensional matrix cultures and long-term monolayer cultures IL-1 beta caused a significant decrease in synthesis and deposition of sulphated proteoglycans, but had no effect on release of deposited material. The decrease in synthesis became successively more pronounced, and corresponded to 40-60% of the control after 72 h incubation. The reduction was almost totally accounted for by an effect on the chondroitin ABC-lyase-sensitive proteoglycans. Gel electrophoresis showed a significant decrease in a high-molecular-mass chondroitin ABC-lyase-sensitive proteoglycan after incubation with IL-1 beta. Northern-blot analyses of total RNA revealed a pronounced decrease in the steady-state mRNA levels of versican, the large chondroitin sulphate, with levels corresponding to 10-30% of controls. In comparison, the steady-state mRNA level for decorin, the major sulphated proteoglycan synthesized by the cells, was only slightly affected. The prominent decrease in synthesis of sulphated proteoglycans induced in long-term fibroblast cultures, including the pronounced decrease in versican steady-state mRNA levels, is likely to have a significant effect on the structure of the extracellular matrix. Induction of this type of change may constitute a significant mechanism whereby IL-1 beta can affect the properties of connective tissue during inflammation and wound healing.

In injury and inflammation, complement (C) component C1q, in addition to its central role in initiation of classical pathway of complement activation, modulates diverse cellular functions by binding to specific cell surface receptors. Interaction of substrate-bound C1q with receptors for the collagen-like domain of C1q (C1qRC) of human gingival fibroblasts (HGF) promotes cell attachment. We investigated modulation of the adhesive function and expression of C1qRC by interleukin-1 beta (IL-1 beta) and transforming growth factor-beta (TGF-beta). Confluent fibroblast monolayers were incubated under standard culture conditions with or without cytokines. C1qRC function was measured by attachment assays. IL-1 beta and TGF-beta increased fibroblast adhesion to C1q to 146% and 131% of controls, respectively. Cytokine enhancement of HGF adhesion was concentration-dependent, saturable (20 ng/ml IL-1 beta; 1 ng/ml TGF-beta) and time-dependent (IL-1 beta 12-hr peak; TGF-beta 24-hr peak). Effect of IL-1 beta and TGF-beta on C1qRC expression was assessed by flow cytometry measurements of fluorescence intensity of cells stained with C1q and FITC anti-C1q antibody, and by binding studies with 125I-C1q. Cells treated with cytokines displayed a two- to four-fold increased fluorescence of cell-bound C1q compared to controls. Binding studies indicated the increased fluorescence correlated with increase in number of C1qRC in both IL-1 beta (4.7 x 10(6)/cell) and TGF-beta (3.9 x 10(6)/cell)-treated cells, compared to control (3.0 x 10(6)/cell), but had no effect on binding affinity. Rates of internalization of receptor-bound C1q were similar in cytokine-treated cells and controls. We propose from these data that IL-1 beta and TGF-beta have the ability to upregulate C1qRC expression, and this effect contributes to increased adhesion of HGF to substrate-bound C1q.

Proteoglycans comprise a part of the extracellular matrix that participates in the molecular events that regulate cell adhesion, migration and proliferation. Their structural diversity and tissue distribution suggest a functional versatility not generally encountered for other extracellular matrix components. This versatility is mainly dictated by their molecular interactions and their ability to regulate the activity of key molecules involved in several biological events. This molecular cooperativity either promotes or inhibits cell adhesion, migration and proliferation. A growing number of studies indicate that proteoglycans can play a direct role in these cellular events by functioning either as receptors or as ligands for molecules that are required for these events to occur. Such studies support a role for proteoglycans as important effectors of cellular processes that constitute the basis of development and disease.

This report describes synthesis and degradation of proteoglycans by human gingival fibroblasts growing in an endogenous three-dimensional matrix. Cells grown in the matrix cultures demonstrated a high rate of proteoglycan synthesis, varying between 2 and 4 times that of cells maintained in monolayer cultures. In addition, the relative amount deposited into the cell layer was increased in the matrix cultures, constituting 70% to 90% of the synthesized material during the first 24 h. Comparable levels for the monolayer cultures were 30% to 60%. The majority of the 35S-sulfate-labeled material in both matrix (80%) and monolayer (62%) cultures was susceptible to chondroitin ABC-lyase digestion. The major product was a low Mr (120,000) proteoglycan which could be immunoprecipitated by an antibody against PGII (decorin). In addition, the cells synthesized two chondroitin ABC-lyase-sensitive proteoglycans, one with Mr greater than 400,000, one with an apparent Mr of 250,000, as well as two heparan sulfate proteoglycans with Mr greater than 250,000. The low Mr dermatan sulfate, decorin, was also the major component deposited in the three-dimensional matrix, constituting about 60% of the total sulfate incorporation. In contrast, fibroblasts in monolayer cultures deposited only a small amount (13%) of decorin (PGII) in the cell layer, and the major proteoglycan in this compartment was heparin sulfate. The rate of release of the newly deposited proteoglycans was the same in the two culture conditions, although material released from the three-dimensional matrix cultures contained small Mr components indicating a higher degree of degradation. These studies show differences in proteoglycan metabolism by gingival fibroblasts grown in an endogenous matrix and in monolayer cultures.(ABSTRACT TRUNCATED AT 250 WORDS)

This study describes the alterations induced by Interleukin-1 alpha and -beta (IL-1 alpha and IL-1 beta) on fibroblast-synthesized extracellular matrix. Fibroblasts were grown between pieces of dentin or in collagen-coated Terasaki wells for 3 or 6-9 weeks to create 3-dimensional cell-containing matrices constituted primarily of proteoglycans and collagens, respectively. Following incubation with IL-1 alpha or IL-1 beta (10(-9) M) at 37 degrees C for 24 or 72 hr, samples were prepared for light and electron microscopy. Both IL-1 alpha and IL-1 beta induced collapse of the extracellular matrix by 72 hr, as manifested by a decrease of the cross-sectional area and an increased density of the matrices. Three-week matrices were reduced 26% and 45% by using IL-1 alpha and IL-1 beta, respectively. Comparable values obtained by using 6-week matrices were 14% and 30%. Cells within the matrix, normally stellate in shape with numerous extended processes, attained a more rounded or spindle shape with few and reduced processes and showed apparent alterations at cell matrix attachment sites and rearrangement of the cytoskeleton. Elongated cells at the top of the matrix appeared more compressed. The alterations were more pronounced in cultures incubated with IL-beta than with IL-1 alpha. Immunocytochemistry of extracellular matrix components revealed a decrease in staining intensity of chondroitin and dermatan sulfate in the 3-week matrix following IL-1 beta incubation. There was also a decrease in collagen type 1 staining of 9-week matrices treated with IL-1 alpha or IL-1 beta. These studies show that IL-1 has an effect on fibroblast-synthesized extracellular matrix and indicate that the effects of IL-1 alpha and IL-1 beta may differ. The resulting collapse of the matrix appears at least in part to be due to changes in proteoglycans and collagens.

An experimental model for sialography, involving retrograde infusion of contrast medium into the rat submandibular gland under continuous pressure monitoring, was developed. Morphologic alterations induced during infusion of water- and lipid-soluble radiographic contrast media and the distribution of the media were examined with light and electron microscopy. An uneven distribution of the media throughout the tissue and variations in the degree of the alterations in different parts of the gland were seen at all stages of filling. The changes primarily consisted of dilation of the luminal system, which successively became more pronounced as infusion continued. Infusion of the lipid-based medium consistently resulted in more severe alterations, including changes in the acini. Tracer studies showed that the water-soluble medium leaked out through the intercellular spaces and to the surrounding tissue, whereas the lipid-based medium appeared to be confined to the luminal space. Ductal filling with either medium resulted in a relatively fast recovery; after prolonged infusion, recovery was slower and additional alterations occurred. The acini showed confluence of secretory granules and vacuole formation. After infusion of the lipid-based compound, autophagic vacuoles and granulomatous alterations developed. Prolonged infusion with either medium resulted in atrophy of the parenchyma and connective tissue proliferation in some glands. An inflammatory infiltrate was present in all glands during the recovery period. Functional alterations, primarily consisting of a decrease in flow rate, were noted after prolonged infusion. The increase in intraluminal pressure induced during infusion was most likely the primary cause of the alterations. In addition, the presence of contrast medium contributed to the long-term effects of the procedure.

Development and maturation of an extracellular matrix, synthesized by human gingival fibroblasts, have been studied microscopically. Pairs of demineralized, fibronectin-coated slices of human tooth root, 300 micron thick, were placed on confluent cell layers, defining a 0.5 mm wide space. The cultures were grown under standard conditions with ascorbic acid (50 micrograms ml-1) added daily. At various times up to 13 weeks, the cultures were fixed and the samples prepared for light and electron microscopy. Cells from the monolayer became attached to, and migrated up, the vertical root surface and, during the time studied, completely filled the space between the root slices with an extracellular matrix. A close association was seen between the cell membrane and collagen fibres in the demineralized surface initially. A thin layer of fibrillar material was deposited between the cell and the vertical surface, and eventually an extracellular matrix surrounding the cells and attaching to the root surface was present. Samples fixed in the presence of Ruthenium Red showed intense staining of the fibrillar material, indicating the presence of anionic molecules. Additional cells migrated onto the newly synthesized matrix and up the root surface. Growth of the fibrillar networks on either side, horizontally and vertically, continued and, eventually, an extracellular matrix attaching to the vertical surfaces completely filled the previously empty space. Immunocytochemical staining showed that the matrix contained hyaluronic acid, chondroitin sulphate, dermatan sulphate and fibronectin at this time. Collagen fibres were observed at 6 weeks, and at later times collagen types I, III and V were the primary matrix components. The fibroblasts attaching to the root slice and those present at the edge of the matrix had an elongated, polar form. The cells within the matrix frequently showed a stellate appearance with numerous extended processes, in contact with fibrillar material or collagen fibres. Fibroblast processes were at later times seen to enclose bundles of collagen fibres and to mediate cell-to-cell contact, occasionally via desmosome-like structures. The structure and composition of the matrix and the appearance and apparent behaviour of the cells were similar to that observed in the healing wound. This system thus could provide a model for studying various aspects of regeneration of extracellular matrix.

For microscopic visualization, horseradish peroxidase (HRP; 10 mg/ml) was added to the contrast medium. Some glands were infused with saline solution containing HRP. During continuous infusion, the intraglandular pressure was recorded. Infusion was stopped at different phases of the pressure curve and the glands fixed by vascular perfusion. Morphological alterations, principally dilatation of the intralobular ducts, were most pronounced in the intercalated duct segment. HRP was first observed in the lumina of the intralobular ducts and acini but gained access to the intercellular spaces thought the apical junctional complexes and subsequently surrounded various cellular components. Eventually the tracer was found in blood and lymphatic vessels. Because of an uneven distribution of the tracer and variation in the degree of filling in different areas of the same gland, the development of the intraglandular pressure could not be directly correlated with specific morphological alterations but is thought to reflect all events occurring in the tissue at a particular time.