Modulation of fibroblast growth and glycosaminoglycan synthesis by interleukin-1

Xylosyltransferase I mediates the synthesis of proteoglycans with long glycosaminoglycan chains and controls chondrocyte hypertrophy and collagen fibers organization of in the growth plate

Genetic mutations in the Xylt1 gene are associated with Desbuquois dysplasia type II syndrome characterized by sever prenatal and postnatal short stature. However, the specific role of XylT-I in the growth plate is not completely understood. Here, we show that XylT-I is expressed and critical for the synthesis of proteoglycans in resting and proliferative but not in hypertrophic chondrocytes in the growth plate. We found that loss of XylT-I induces hypertrophic phenotype-like of chondrocytes associated with reduced interterritorial matrix. Mechanistically, deletion of XylT-I impairs the synthesis of long glycosaminoglycan chains leading to the formation of proteoglycans with shorter glycosaminoglycan chains. Histological and Second Harmonic Generation microscopy analysis revealed that deletion of XylT-I accelerated chondrocyte maturation and prevents chondrocytes columnar organization and arrangement in parallel of collagen fibers in the growth plate, suggesting that XylT-I controls chondrocyte maturation and matrix organization. Intriguingly, loss of XylT-I induced at embryonic stage E18.5 the migration of progenitor cells from the perichondrium next to the groove of Ranvier into the central part of epiphysis of E18.5 embryos. These cells characterized by higher expression of glycosaminoglycans exhibit circular organization then undergo hypertrophy and death creating a circular structure at the secondary ossification center location. Our study revealed an uncovered role of XylT-I in the synthesis of proteoglycans and provides evidence that the structure of glycosaminoglycan chains of proteoglycans controls chondrocyte maturation and matrix organization.

TMEM165 a new player in proteoglycan synthesis: loss of TMEM165 impairs elongation of chondroitin- and heparan-sulfate glycosaminoglycan chains of proteoglycans and triggers early chondrocyte differentiation and hypertrophy

TMEM165 deficiency leads to skeletal disorder characterized by major skeletal dysplasia and pronounced dwarfism. However, the molecular mechanisms involved have not been fully understood. Here, we uncover that TMEM165 deficiency impairs the synthesis of proteoglycans by producing a blockage in the elongation of chondroitin-and heparan-sulfate glycosaminoglycan chains leading to the synthesis of proteoglycans with shorter glycosaminoglycan chains. We demonstrated that the blockage in elongation of glycosaminoglycan chains is not due to defect in the Golgi elongating enzymes but rather to availability of the co-factor Mn²⁺. Supplementation of cell with Mn²⁺ rescue the elongation process, confirming a role of TMEM165 in Mn²⁺ Golgi homeostasis. Additionally, we showed that TMEM165 deficiency functionally impairs TGFβ and BMP signaling pathways in chondrocytes and in fibroblast cells of TMEM165 deficient patients. Finally, we found that loss of TMEM165 impairs chondrogenic differentiation by accelerating the timing of Ihh expression and promoting early chondrocyte maturation and hypertrophy. Collectively, our results indicate that TMEM165 plays an important role in proteoglycan synthesis and underline the critical role of glycosaminoglycan chains structure in the regulation of chondrogenesis. Our data also suggest that Mn²⁺ supplementation may be a promising therapeutic strategy in the treatment of TMEM165 deficient patients.

Inflammatory Regulation of CNS Barriers After Traumatic Brain Injury: A Tale Directed by Interleukin-1

Several barriers separate the central nervous system (CNS) from the rest of the body. These barriers are essential for regulating the movement of fluid, ions, molecules, and immune cells into and out of the brain parenchyma. Each CNS barrier is unique and highly dynamic. Endothelial cells, epithelial cells, pericytes, astrocytes, and other cellular constituents each have intricate functions that are essential to sustain the brain's health. Along with damaging neurons, a traumatic brain injury (TBI) also directly insults the CNS barrier-forming cells. Disruption to the barriers first occurs by physical damage to the cells, called the primary injury. Subsequently, during the secondary injury cascade, a further array of molecular and biochemical changes occurs at the barriers. These changes are focused on rebuilding and remodeling, as well as movement of immune cells and waste into and out of the brain. Secondary injury cascades further damage the CNS barriers. Inflammation is central to healthy remodeling of CNS barriers. However, inflammation, as a secondary pathology, also plays a role in the chronic disruption of the barriers' functions after TBI. The goal of this paper is to review the different barriers of the brain, including (1) the blood-brain barrier, (2) the blood-cerebrospinal fluid barrier, (3) the meningeal barrier, (4) the blood-retina barrier, and (5) the brain-lesion border. We then detail the changes at these barriers due to both primary and secondary injury following TBI and indicate areas open for future research and discoveries. Finally, we describe the unique function of the pro-inflammatory cytokine interleukin-1 as a central actor in the inflammatory regulation of CNS barrier function and dysfunction after a TBI.

The effects of TGF-alpha, IL-1beta and PDGF on fibroblast adhesion to ECM-derived matrix and KGF gene expression

The goal of this study was to elucidate the control mechanisms by which exogenous proteins regulate keratinocyte growth factor (KGF) expression in fibroblasts adhered to differing substrates and thereby provide insights into both fundamental in vitro cell signaling and cell-biomaterial interaction research. A serum-free culture system in which cells maintained their proliferative capacity was established and employed. The addition of transforming growth factor- alpha (TGF-alpha), interleukin-1beta (IL-1beta) and platelet-derived growth factor-BB (PDGF-BB) individually showed no effect on KGF protein release, however, IL-1beta addition led to increased KGF mRNA transcription, intracellular KGF protein synthesis, and granulocyte-macrophage colony-stimulating factor (GM-CSF) release. Intracellular KGF protein synthesis and extracellular release were enhanced when fibroblasts were treated with a combination of IL-1beta and PDGF-BB which suggests KGF synthesis and release are largely regulated by synergistic mechanisms. Surface-bound fibronectin-derived ligands and individual exogenous proteins promoted fibroblast adhesion to semi-interpenetrating polymer networks (sIPNs) but did not stimulate KGF release despite enhancement of KGF mRNA transcription. Additionally, serum conditioning was found to have a significant impact on KGF synthesis and the subsequent mechanisms controlling KGF release. This study demonstrates that KGF release from fibroblasts is likely regulated by multiple mechanisms involving post-transcriptional and exocytic controls which may be impacted by the presence of serum and how serum is removed from the in vitro cell environment.

Reversal of photodamage with topical growth factors: a pilot study

BACKGROUND

Interest in the reversal of facial photodamage has increased significantly among patients and physicians in the past decade. Though surgical procedures may be very effective, the associated healing time and potential risks have spurred the development of non-surgical treatments. There has also been an increasing depth of knowledge regarding wound healing and its control by growth factors as well as its modulation by the topical application of growth factors. Bioengineered tissue cultures have resulted in the ability to collect naturally occurring human growth factors in their tissue concentrations.

OBJECTIVE

The objective of this study is to determine if the twice daily application of a combination of multiple growth factors to photodamaged facial skin results in any evidence of improvement after 60 days.

METHODS

Fourteen patients applied a gel containing a mixture of eight different growth factors (Nouricel-MD) to photodamaged facial skin twice daily. Prior to the study and at days there were clinical evaluations of photodamage (Fitzpatrick scale), 3 mm punch biopsies and optical profilometry. Patient questionnaires were answered at 60 days.

RESULTS

Eleven of 14 patients showed clinical improvement in at least one facial area. The peri-orbital region showed a statistically significant improvement (p = 0.0003). Optical profilometry showed a statistically significant reduction in Ra measurement (p=0.0075) and shadowing (p=0.02), both indicating a decrease in the depth and number of textural irregularities or fine lines. Biopsies revealed new collagen formation in the Grenz zone (37% increase in thickness) and thickening of the epidermis by 27%. Eight of 14 patients felt their wrinkles were improved, while 12 of 14 felt their skin texture was improved.

CONCLUSIONS

The application of a mixture of topical growth factors may stimulate the repair of facial photodamage resulting in new collagen formation, epidermal thickening and the clinical appearance of smoother skin with less visible wrinkling.

Trauma and alkali burns induce distinct patterns of cytokine gene expression in the rat cornea

Cytokines such as the interleukins (IL) and tumor necrosis factor alpha (TNF alpha) have traditionally been associated with paracrine regulation of immune reactions. These proteins also have properties suggestive of functional roles in the inflammatory and reparative responses to tissue injury. In this study, mRNA levels for IL-1 alpha, IL-1 beta, IL-6, TNF alpha, interferon gamma, transforming growth factor beta 1, and CD4 were monitored in rat corneas at times from 1 hour through 2 weeks after incisional trauma or alkali burns. Transcripts for IL-1 alpha, TNF alpha, and TGF beta 1 were present in most corneal samples; whereas those for IFN gamma and CD4 were not detected. As early as 1 hour following either of these non-immunologic forms of injury, expression of IL-6 mRNA levels was induced. Only in corneas with alkali burns did IL-6 induction persist from days 1 through 7. The alkali-injured corneas also had markedly increased IL-1 beta mRNA levels from days 1 through 7. These observations indicate that cytokine mRNA is induced in the cornea by trauma without an apparent immunologic stimulus. Our data are consistent with the hypothesis that corneal tissues respond to different types of injury with different patterns of cytokine gene expression.

Modification of alveolar macrophage function with bis-basic ethers of fluorene and fluoren-9-substituted derivatives

Bis-basic ethers of fluorene and fluoren-9-substituted derivatives such as tilorone have been reported to inhibit silica-induced fibrosis in rats. The potential antifibrotic potency of 2,7-bis(diethylamino)ethoxy fluorene (F-9-H,H), fluorenone (F-9-one), fluorenoxime (F-9-oxime), and fluorenol (F-9-ol) was F-9-oxime > F-9-one approximately F-9-H,H >> F-9-ol. Since the release of reactive oxygen species and growth factors from alveolar macrophages (AM) in response to silica exposure has been linked to the development of pulmonary fibrosis, the present study was carried out to determine the inhibitory effects of these compounds on rat AM activity in vitro. The following parameters were monitored: (1) cellular viability; (2) zymosan-induced respiratory burst activity (superoxide and hydrogen peroxide release, chemiluminescence, and oxygen consumption) of AM; (3) drug binding to AM; and (4) lipopolysaccharide (LPS)-stimulated interleukin-1 (IL-1) release from AM. The bis-basic ethers, at 40 microM, did not affect cell viability when incubated with AM for 30 min, but significantly inhibited zymosan-induced macrophage respiratory burst activity. The inhibitory effect of these agents was F-9-oxime > F-9-one approximately F-9-H,H >> F-9-ol. Binding of these drugs to AM was time and dose dependent, and exhibited the following binding affinity: F-9-oxime > F-9-one > F-9-H,H > F-9-ol. F-9-oxime was shown to inhibit LPS-stimulated IL-1 release by AM in a dose-dependent manner. This inhibition of IL-1 release by AM cannot be explained as a decrease in viability. In addition, these drugs were also shown to impair human fibroblast proliferation in response to serum stimuli without impairing cell viability. These results indicate a positive correlation between drug binding to AM or other cell types and their inhibitory effects on cellular activities including oxygen consumption, superoxide release, hydrogen peroxide secretion, chemiluminescence, IL-1 release, and proliferation. The ability of these bis-basic ethers to modify AM and fibroblast functions in vitro suggests that further investigation of their reported antifibrotic potency in vivo is warranted.

Intracellular signal transduction for serum activation of the hyaluronan synthase in eukaryotic cell lines

Hyaluronan synthase was activated in B6 cells or 3T3 fibroblasts by foetal calf serum with maximal activity after 6 h. Activation was inhibited by cycloheximide or by the protein kinase inhibitors H-7 or H-8, indicating that transcription as well as phosphorylation was required for activation. The activation by serum was markedly prolonged, when serum was added together with cholera toxin or theophylline. Without serum stimulation the hyaluronan synthase could also be activated by phorbol-12-myristate-13-acetate, by dibutyryl-c-AMP, or by forskolin. Increasing the intracellular Ca-ion concentration with a Ca-ionophore also led to an activation. The activation of the drugs was not synergistic. In isolated plasma membranes the synthase activity could be decreased by phosphatase treatment and enhanced by ATP in B6 cells and by ATP in the presence of phorbol-12-myristate-13-acetate in 3T3 fibroblasts. Stimulation correlated with increased transcription and phosphorylation of the 52 kD hyaluronan synthase at serine residues. The results led to the conclusion that hyaluronan synthase is induced by transcription and activated by phosphorylation by protein kinase C, c-AMP-dependent protein kinases, or Ca-ion-dependent protein kinases.

Serum hyaluronic acid and interleukin-6 as possible markers of carpal tunnel syndrome in chronic hemodialysis patients

To elucidate the precise mechanism of carpal tunnel syndrome (CTS), serum hyaluronic acid (HA), interleukin-1 beta (IL-1 beta), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-alpha) were measured in 71 chronic hemodialysis patients with or without CTS and/or shoulder pain. Patients were divided into two groups: Group 1 (n = 40) was the control group, and Group 2 (n = 31) patients had carpal tunnel syndrome, shoulder pain, or both. None of the patients had liver disease, rheumatoid arthritis, other inflammatory disease, or cancer. Serum HA concentrations in Groups 1 and 2 were 106.0 +/- 77.5 and 442.6 +/- 564.7 ng/dl (mean +/- SD), respectively. The difference between the groups was significant (p < 0.01). The serum concentrations of IL-6 in Group 1 were significantly lower than in Group 2 (p < 0.05); however, there was no significant difference in serum IL-1 beta and TNF-alpha levels. The mechanisms regulating in vivo synthesis of HA was obscure; however, in vitro studies suggest that inflammatory cytokines may stimulate an increased production of HA. In this study, CTS might be associated with increased serum concentrations of HA, and HA production might be mediated by IL-6.

Changes in the extracellular matrix of the autogenous patellar tendon graft after posterior cruciate ligament reconstruction: a biochemical study in sheep

The left knee joints of female German sheep were operated, replacing the posterior cruciate ligament by the central third of the patellar tendon. After 2, 6, 16, 26 and 52 weeks the graft of the operated leg as well as the contralateral central third of the patellar tendon and the posterior cruciate ligament were dissected and used for biochemical analysis. The total glycosaminoglycan content in grafts increases within the first year up to 5 fold and is higher than that of the patellar tendon, but is lower than that of the cruciate ligament. The distribution pattern of glycosaminoglycans differ in the posterior cruciate ligament and the patellar tendon. In cruciate ligament the main components are chondroitin sulfate (76%) and hyaluronan (15%). In the patellar tendon a higher portion of dermatan sulfate (approx. 16%) was found, next to 52% chondroitin sulfate and 22% hyaluronan. During the examination time the grafts show changes in the concentration and the distribution pattern of glycosaminoglycans. The chondroitin sulfate content increases during the experimental period from 1.4 +/- 1.2 mumol/g dry weight (d.w.) to 8.7 +/- 2.9 mumol/g d.w. After 1 year the chondroitin sulfate content in the graft does not differ significantly from that of the cruciate ligament. In the grafts the concentration of chondroitin (non sulfated) increases after 6 weeks up to 1.3 +/- 0.6 mumol/g d.w. in comparison to the value after 2 weeks (0.2 +/- 0.1 mumol/g d.w.) and also in the other groups (16, 26 and 52 weeks) it remains significantly increased. After 1 year the dermatan sulfate content in the graft has increased up to the fifth-fold compared to the value after 2 weeks and is higher than in the patellar tendon and in the cruciate ligament. In graft the hyaluronan content (1.0 +/- 0.4 mumol/g d.w. does not differ significantly in the groups 2, 6, 16, 26 and 52 weeks after operation, but in all five groups it is lower than in the cruciate ligament (2.4 +/- 1.0 mumol/g d.w.). Dermatan and heparan sulfate are not or only little detected in all three tissues. The distribution pattern of glycosaminoglycans in graft shows chondroitin sulfate and dermatan sulfate being the major parts of glycosaminoglycans with a slight increase of these components in the different groups during the experimental period. Hyaluronan makes up to 24 +/- 5% of the whole content of glycosaminoglycans after 2 weeks and decrease to 8 +/- 1% after 52 weeks.(ABSTRACT TRUNCATED AT 400 WORDS)

Function of peritoneal exudate cells after abdominal surgery

Peritoneal macrophages and polymorphonuclear neutrophils are key cells in the repair of postoperative injury. Increased numbers of macrophages migrate into the peritoneal cavity after operation and the function of these cells changes over the postoperative interval. Macrophage activities, such as respiratory burst, arachidonic acid metabolism, monokine secretion, and plasminogen activator inhibitory activity, are elevated by peritoneal operation. However, the secretion of plasminogen activator activity is decreased after operation. The kinetics with which each of these functions changes varies with the parameter examined, indicating a complex regulation of the differentiation of leukocytes after operation. In addition, the activity of postoperative macrophages can be modulated in vitro by exposure to cytokines and conditioned media from polymorphonuclear neutrophils and macrophages. Thus, cell-cell interactions and factors secreted within the peritoneal cavity may regulate the contribution of postoperative leukocytes to peritoneal repair after operation.

Modulation of peritoneal re-epithelialization by postsurgical macrophages

The studies reviewed here show that postsurgical macrophages are capable of modulating the proliferation of TRC. That is, macrophages either suppress or enhance the proliferation of TRC depending on the culture time and the medium used as a comparison, i.e., culture medium with only serum or spent medium from cultures of resident peritoneal macrophages. Postsurgical macrophages also modulate the morphology of (spindly or rounded appearance) and the secretion of extracellular matrices by TRC. The responsivity of TRC to control by postsurgical macrophage-spent media or growth factors changes as a function of postsurgical and/or culture time. In addition, cells harvested from the site of peritoneal trauma (TRC) did not respond to growth factors in a fashion entirely the same as fibroblasts. This indicates that cells harvested from the site of peritoneal injury are unique. Lastly, after removal of a suppressive factor from postsurgical macrophage-spent media by dialysis, the factors secreted by postsurgical macrophages are more potent in enhancing TRC proliferation than growth factors individually.

Inhibitory action of tetrandrine on macrophage production of interleukin-1 (IL-1)-like activity and thymocyte proliferation

Tetrandrine is a bisbenzylisoquinoline alkaloid which has been shown to exhibit antifibrotic activity against silicosis. Tetrandrine is characterized by its strong binding to alveolar macrophages and inhibition of particle-induced respiratory burst activity in these phagocytes. In contrast, tubocurine and tubocurarine are structurally similar to tetrandrine but exhibit little effect on fibrosis or activation of alveolar macrophages. The objective of the present study was to test the effect of tetrandrine on macrophage production of monokines in response to occupational dusts, and to determine tetrandrine's effect on monokine-medicated cell growth using a mouse thymocyte proliferation assay and lipopolysaccharide (LPS) as a positive control. Stimulation of alveolar macrophages by respirable silica dust resulted in a release of monokines which caused a fourfold increase in thymocyte proliferation. Coal dust, on the other hand, had no effect on macrophage production of this cytokine. Tetrandrine was found to exhibit a dose-dependent inhibition of monokine release from both silica and LPS-stimulated alveolar macrophages. In experiments where thymocytes were directly treated with tetrandrine, a dose-dependent inhibition of thymocyte proliferation was noted with both interleukin-1-(IL-1) specific and nonspecific mitogenic (concanavalin A) actions. In contrast to the inhibitory potency of tetrandrine, tubocurarine was found to have no effect on either the production of monokines by LPS-stimulated alveolar macrophages or IL-1-mediated thymocyte proliferation. These results provide a correlation between the antifibrotic effect of tetrandrine and inhibition of macrophage activation.

Binding and internalization of hyaluronate by human cutaneous fibroblasts

Hyaluronate is a ubiquitous component of mammalian extracellular matrix. It influences numerous cellular processes and accumulates in fibrotic connective tissue disorders. Recently, hyaluronate catabolism has assumed additional importance because of the introduction into clinical practice of therapeutic procedures which deposit high concentrations of hyaluronate directly into tissues. Relatively little is known about the local metabolism, fate, or long-term effects of either endogenous or exogenous hyaluronate at deposition sites. A capacity for degrading hyaluronate within connective tissues, presumably by fibroblasts, has been inferred but remains controversial because direct proof that human fibroblasts endocytose and degrade hyaluronate has been lacking. In the present study, fibroblasts from normal and fibrotic skin were incubated with [3H]-hyaluronate. Binding and internalization of radiolabeled substrate were then measured: Binding assays revealed a saturable, dose-dependent increase in cell surface-associated [3H]-hyaluronate which was enhanced by pretreatment with hyaluronidase. Similar binding curves were obtained for all cells tested. All the cell lines internalized hyaluronate; however, fibroblasts in confluent cultures internalized 3.5- to 4.2-fold more radioactivity per cell than did fibroblasts from corresponding subconfluent cultures (p less than or equal to 0.002). Normal scar fibroblasts showed greater capacity for generating hyaluronate-derived partial degradation products. This work provides clear evidence that human cutaneous fibroblasts are capable of both binding and internalizing hyaluronate, possibly as a prerequisite for degradation.

Comparative effects of interleukin-1 and tumor necrosis factor-alpha on collagen production and corresponding procollagen mRNA levels in human dermal fibroblasts

The effects of recombinant human Interleukin-1 alpha (IL-1 alpha), Interleukin-1 beta (IL-1 beta), and Tumor Necrosis Factor-alpha (TNF-alpha) on collagen biosynthesis were studied in vitro using dermal fibroblast cultures. Both forms of IL-1 and TNF-alpha induced a dose-dependent inhibition of both types I and III collagen synthesis, as measured by radioimmunoassay, gel electrophoresis, or collagenase-sensitive material. This effect was accompanied by a significant release of prostaglandin E2 into the culture medium. However, indomethacin, a potent inhibitor of prostaglandin synthesis, could not prevent the inhibitory effect of the three cytokines on collagen synthesis. Measurement of type I and type III procollagen mRNA levels in IL-1 treated cells revealed that both IL-1 alpha and IL-1 beta were potent enhancers of procollagen gene expression at pretranslational level. On the other hand, TNF-alpha was found to reduce the steady-state levels of type I and III procollagen mRNA in a dose-dependent manner. Quantitation of IL-1 beta and TNF-alpha transcripts following TNF-alpha treatment of fibroblasts indicated that this cytokine can induce IL-1 beta gene expression in these cells. By contrast, TNF-alpha mRNA remained at a constant level after TNF-alpha exposure. These data suggest that IL-1 and TNF-alpha, two cytokines that share several biologic activities, modulate collagen deposition in dermal fibroblasts by mechanisms that are clearly different: TNF-alpha appears to act at a transcriptional level to inhibit collagen synthesis, whereas IL-1 inhibitory action involves important translational regulation, still unknown, that counterbalances its stimulatory effect on procollagen mRNA levels. Moreover, our data suggest the existence of local fibroblastic cytokine production that may be involved in the modulation of extracellular matrix deposition.

Kinetics of interleukin-1 and tumor necrosis factor secretion by rabbit macrophages recovered from the peritoneal cavity after surgery

Macrophages play a crucial role in wound healing after surgical injury, both as scavenger cells responsible for wound debridement and as cells that secrete soluble factors such as interleukin-1 (IL-1) and tumor necrosis factor (TNF). IL-1 and TNF alter many of the biological activities of cells that appear in postsurgical wounds. In this study, we determined the kinetics of IL-1 and TNF production by rabbit macrophages harvested from postsurgical peritoneal exudate (postsurgical macrophages) at several time points after peritoneal surgery. To further characterize the level of functional activities of postsurgical macrophages, the IL-1 and TNF levels were determined with or without stimulating the cells with lipopolysaccharide (LPS) and phorbol myristate acetate (PMA). After surgery, the number of macrophages harvested by peritoneal lavage increased, reached peak levels on postsurgical day 3, and then decreased. IL-1 levels secreted by macrophages cultured without stimuli were elevated on postsurgical day 14 compared to the values on day 3 and 7. TNF concentrations peaked on days 1 and 14. In the conditioned culture media from LPS-PMA-stimulated macrophages, the levels of both IL-1 and TNF peaked on postsurgical days 3 and 14. These data suggest that the susceptibility of postsurgical macrophages to stimuli changes during the wound healing process with maximum sensitivity to the stimuli present during the early phase of peritoneal repair (day 3).

Expression of different glycosaminoglycan synthetic phenotypes by lapine dermal and dermal wound fibroblasts

Synthesis of extracellular matrix by dermal fibroblasts is an important component of cutaneous wound repair. Scar remodeling and maturation is generally seen as the result of a fibroblast-regulated equilibrium between production and degradation of specific matrix constituents. Fibroblasts from normal dermis, reparative granulation tissue and mature scars were compared in vitro in terms of their ability to produce extracellular glycosaminoglycans (GAGs). All cell lines secreted dermatan sulfate (DS) and chondroitin sulfate (CS) into the culture medium. Hyaluronate (HA) was detected in medium from mature granulation tissue and scar cells, but little or none was found in medium from early granulation tissue or skin cells. In medium from normal skin fibroblasts, an unusual GAG was identified as a potential variant of DS on the basis of co-migration with HA but susceptibility to digestion with chondroitinase ABC. Heparan sulfate (HS) was the major pericellular GAG of all cultures except the mature scar cells, which contained a predominance of DS. A second pericellular GAG was identified as CS in mature granulation tissue cells, scar cells and skin cells; while HA was identified in the pericellular matrix of early granulation tissue cells. In addition, fibroblasts from both skin and early granulation tissue contained a GAG believed to be a variant of CS. These differences in GAG synthesis/secretion between cells maintained under identical culturing conditions could indicate either that distinct fibroblastic substrains exist during different stages of healing or that influences present during the healing process induce stable phenotypic alterations that are maintained through explant culturing and subsequent subcultivation.

The induction of specific metabolic alterations in mouse calvarial organ cultures by glycosaminoglycans

Glycosaminoglycans specifically regulate the amount of calcium released from bone cultures; the mechanisms responsible for this regulation are not known. Media from glycosaminoglycan-stimulated bone organ cultures were analysed to determine (1) if specific calcium-releasing substances were selectively produced, and (2) if protein synthesis was differentially affected by glycosaminoglycans. Chondroitin sulphate B, hyaluronic acid and keratan sulphate at 100 micrograms/ml significantly increased prostaglandin release when compared with control cultures. In combination with suboptimal concentrations of PTH, chondroitin sulphate B, heparin and keratan sulphate significantly stimulated prostaglandin release. When indomethacin was included in the test assays, the stimulated prostaglandin release was abolished. Heparin-treated cultures released the greatest percentage of latent collagenase activity followed by hyaluronic acid-treated cultures. Organ cultures treated with heparin and PTH amount of active collagenase. Stimulation increased interleukin-1 above control levels but with no significant difference among the glycosaminoglycans except for keratan sulphate cultures with which had the greatest amount of interleukin-1. Collagen protein decreased between 48 and 72 h under both control and experimental conditions. Examination of the predominant [35S]-methionine labelled proteins revealed that prostaglandin E2 treatment resulted in a relative shift in labelling to higher molecular-weight proteins as time in culture increased (up to 144 h). After 48 h, when equal amounts of labelled protein were analysed, there was a predominance in labelling of a 200,000 Da protein in the prostaglandin-treated cultures. These findings demonstrate that modulation of calcium release by glycosaminoglycans results in the selective release of molecules capable of stimulating calcium release.(ABSTRACT TRUNCATED AT 250 WORDS)

Kinetics of interleukin-1 secretion by murine macrophages recovered from the peritoneal cavity after surgery

Macrophages play a central role in wound healing after surgical injury possibly through the secretion of soluble factors like interleukin-1 (IL-1). IL-1 has many biological activities which regulate most of the cell types that appear in postsurgical wounds. In this study, we determined the levels of IL-1 production by murine macrophages harvested from postsurgical exudate at several time points after standardized peritoneal surgery. To further characterize the level of functional activities of postsurgical macrophages, the IL-1 levels were determined with or without stimulating the cells with lipopolysaccharide (LPS) and phorbol myristate acetate (PMA). After surgery, the number of macrophages harvested by peritoneal lavage increased, reached peak levels on Postsurgical Day 3, and then decreased. IL-1 levels secreted by macrophages cultured without stimuli gradually increased after surgery, reaching peak levels on Day 10. In conditioned media from LPS-PMA-stimulated macrophages, IL-1 levels were significantly greater than in media from unstimulated macrophages and peaked on Postsurgical Day 3. These data suggest that the susceptibility of postsurgical macrophages to stimuli changes during the postsurgical wound healing process. Accordingly, IL-1 may play an important role in the late rather than in the early phase of peritoneal repair.

Differential regulation of collagen, glycosaminoglycan, fibronectin, and collagenase activity production in cultured human adult dermal fibroblasts by interleukin 1-alpha and beta and tumor necrosis factor-alpha and beta

In order to clarify the role played by immunologically derived cytokines in dermal connective tissue synthesis and degradation, we investigated the effect of human recombinant (hu-r) interleukin (IL) 1-alpha and beta, hu-r tumor necrosis factor (TNF)-alpha and beta, hu-r IL 2, and hu-r granulocyte-macrophage colony-stimulating factor (GM-CSF) on the production of collagen, glycosaminoglycan, fibronectin, and collagenase activity by three lines of cultured human adult dermal fibroblasts. Our results show that 24-72 h treatment of confluent fibroblast cultures with IL 1-alpha or beta or TNF-alpha or beta causes concentration (1 to 1 X 10(4) U/ml) dependent increases in collagen, glycosaminoglycan, and collagenase activity production, but decreases in fibronectin production. In contrast, treatment with IL 2 and GM-CSF had no effect on fibroblast functions. The data show that IL 1-alpha and beta and TNF-alpha and beta differentially regulate fibroblast functions, and that increases in catabolic functions like collagenase activity production are more than tenfold greater than increases in anabolic functions like collagen production. When these results are considered along with other reports, they suggest that IL 1 and TNF may play predominately a catabolic role in situ during dermal fibrotic responses by directly inhibiting fibronectin production and indirectly causing the degradation of collagen and glycosaminoglycan by significantly increasing dermal fibroblast elaboration of collagenase and proteoglycanase activities.

Fibroblastic subpopulations in uninjured and wounded rabbit oral mucosa

Fibroblast cultures derived from uninjured and reparative rabbit buccal mucosa were compared in terms of extracellular glycosaminoglycan (GAG) content and cellular response to interleukin-1 (IL-1). Under identical growth conditions, proliferation of both cell lines was the same. Both lines incorporated [3H]-glucosamine into GAG in cellular, pericellular, and medium fractions, with the majority of incorporated label residing in the medium. Dermatan sulfate (DS) was the predominant GAG in the medium fraction of both normal and wound fibroblast cultures; however, the two cell lines differed in the identity of the medium fraction's secondary GAG: chondroitin sulfate (CS) for normal fibroblasts and hyaluronic acid (HA) for wound-derived cells. The GAG content of the pericellular matrix for all cultures was the same regardless of the tissue of origin: heparan sulfate (HS) accompanied by a very small amount of CS. Exposure to IL-1 produced limited but highly specific effects: It was not mitogenic for either cell line but did cause a quantitative change (increase) in overall incorporation into GAG for medium and pericellular fractions for both cell lines. Further, IL-1 induced a qualitative change in GAG composition for normal mucosal fibroblastic medium fractions by causing the synthesis/release of heparan sulfate (HS) and a variant form of DS. These data support the hypothesis that different fibroblastic substrains can populate a given oral site as a function of variables such as injury and/or healing status.

Healing of cutaneous and mucosal wounds grafted with collagen-glycosaminoglycan/silastic bilayer membranes: a preliminary report

This report describes the healing of cutaneous wounds in experimental animals grafted with collagen-glycosaminoglycan (GAG) matrix/Silastic (Dow Corning Corp., Midland, MI) bilayers; assesses the feasibility of using collagen-GAG matrix as a vehicle for delivering culture-selected, autogenous fibroblasts to cutaneous wound sites; and evaluates the use of collagen-GAG/Silastic bilayers as mucosal substitutes. Cutaneous and mucosal wounds in New Zealand white rabbits were grafted with either acellular collagen-GAG/Silastic membrane or collagen-GAG/Silastic membrane previously seeded with cultured autogenous fibroblasts. Over 63 days, wound sites were analyzed at intervals based on wound contraction and histology. Cutaneous wound successfully incorporated grafted collagen-GAG matrix and were significantly inhibited in their rate and extent of wound contraction. Seeding membrane matrices with autogenous, cultured fibroblasts before grafting caused a marked increase in cellularity that persisted throughout the postgraft period. In mucosa, matrices were exteriorized rather than incorporated. This work suggests that collagen-GAG/Silastic bilayer may have value as a dermal substitute and, more significantly, may be appropriate as a vehicle for delivering culture-selected fibroblasts to cutaneous wound sites.

Interleukin-1-induced changes in extracellular glycosaminoglycan composition of cutaneous scar-derived fibroblasts in culture

Fibroblast cultures established from explants of mature scar and skin tissue were analyzed with regard to extracellular glycosaminoglycan (GAG) composition and response to interleukin-1 (IL-1). Following a serum-free 48 hour label with [3H]glucosamine, pericellular and medium GAGs were isolated by precipitation with cetylpyridinium chloride (CPC) and analyzed by cellulose acetate electrophoresis. In addition, susceptibility of the precipitates to Streptomyces hyaluronidase, chondroitinase ABC and heparitinase was determined. Labeled conditioned medium from the scar-derived cells contained both dermatan sulfate (DS) and hyaluronate (HA), as compared to medium from the control (skin-derived) cells which contained predominantly DS. IL-1 induced the appearance of chondroitin 4-sulfate (C4-S) in the medium of the scar cells with no concurrent effect on either DS or HA, and increased the amount of HA in the medium fraction of normal skin cells. The pericellular fraction of the scar-derived cells contained chondroitin 6-sulfate (C6-S) and DS; addition of IL-1 resulted in a shift from DS to heparan sulfate (HS), and the emergence of a pericellular GAG profile similar to that of normal dermal fibroblasts.