SEARCH · Search PubMed

Results for “FIBROBLASTS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,297 records · Page 72Linked to original sources

PubMed2000

Air exposure promotes fibroblast growth with increased expression of mitogen-activated protein kinase cascade.

Subepithelial tissue cell types in vivo are separated from air by the surface-covering epithelial layer of various organs, e.g., the skin, cornea, and respiratory and upper alimentary tracts. The epithelial defect caused by inflammatory, traumatic or surgical injury would be expected to expose the subepithelial tissue-localized fibroblasts to influx air. However, it is unclear what effects air stimulation elicits in fibroblast growth, which is critical for wound healing. To address this question, we examined the proliferation of 3T3 fibroblasts with bromodeoxyuridine (BrdU) uptake, using fibroblast-embedded collagen gel culture with or without air exposure. The BrdU intake of air-exposed fibroblasts was about 6 times that of air-nonexposed cells. To further characterize this fibroblast growth, we examined the expression of mitogen-activated protein kinase (MAPK) cascade, which plays a key role in the growth-signaling pathway of various cell types. Immunohistochemistry and Western blotting showed that air exposure increased MAPK cascade expression of the cells more strongly than air nonexposure. The data indicate that air exposure promotes MAPK cascade-associated fibroblast growth, suggesting in turn that in wound repair air stimulation itself may be involved in the basic mechanisms of subepithelial fibroblast proliferation and that it may be related to the pathogenesis of excessive fibroplasia through fibroblast overgrowth.

3T3 Cells↗

PubMed2001

Isolation and characterization of cultured human periodental ligament fibroblast-specific cDNAs.

The molecular mechanisms that control the function of periodontal ligament (PDL) fibroblasts remain unclear. We speculated that the character of differentiating PDL fibroblasts is defined by the altered expansion of specific genes not found in neighboring gingival fibroblasts in the periodontium. To expand this set, subtractive hybridization was applied between cultured human PDL and gingival fibroblasts to identify genes differentially expressed in PDL. Consequently five candidate clones, PDLs (periodontal ligament specific) 5, -17, -22, -25, and -31 were identified and characterized by homology search, Northern analysis, and in situ hybridization. Although the mRNAs of these clones were expressed by bone marrow cells and rarely by gingival fibroblasts, the highest expression was detected in the PDL cells, which were uniformly distributed throughout the whole PDL. Amongst the five candidate clones, we focused on PDLs17, because it is a hypothetical protein whose biological function has not been reported yet in the database. Polyclonal antiserum raised against PDLs17 peptide was made, and stained the PDL fibroblasts, osteoblast-like cells and stromal cells in the bone marrow, but not gingival fibroblasts. The results suggest that clones, PDLs5, -17, -22, -25, and -31 may be used as PDL fibroblast-specific markers, and that PDLs17 could act as an important factor in the differentiation process of PDL fibroblasts.

Blotting, Northern↗

PubMed1994

Thrombin stimulates fibroblast-mediated collagen lattice contraction by its proteolytically activated receptor.

Fibroblast contraction is proposed to play an important role in tissue contraction during events such as wound healing. Thrombin has been implicated to promote force generation in fibroblasts; however, its extracellular mode of action is unclear. The purpose of this study was to determine the role thrombin and the activation of its receptor plays in promoting the contraction of human fibroblasts in an in vitro collagen lattice contraction assay. Human alpha-thrombin promoted fibroblast contraction in a dose-dependent manner with maximal activity at 0.2 nM. In contrast, both hirudin-alpha-thrombin and D-phenylalanyl-L-propyl-L-arginyl chloromethyl ketone-alpha-thrombin, which lack enzymatic activity, failed to elicit fibroblast contraction. Thus, the enzymatic activity of thrombin appears to be necessary for promotion of fibroblast contraction. Northern analysis confirmed that these human fibroblasts expressed mRNA for the human alpha-thrombin receptor. Moreover, the synthetic peptide (SFLLRNPND-KYEPF) representing the "tethered ligand" portion of the activated alpha-thrombin receptor promoted fibroblast contraction, while a control isomer peptide, in which the first two amino acids were reversed, failed to elicit this response. These findings indicate that alpha-thrombin promotes the contraction of adult human fibroblasts and that cleavage of the human alpha-thrombin receptor is sufficient to produce this response.

Amino Acid Chloromethyl Ketones↗

PubMed1998

Modulated response to cytokines of human wound healing myofibroblasts compared to dermal fibroblasts.

Myofibroblasts play an important role in normal wound healing. They are present transiently during tissue repair. Their differentiation from fibroblasts and their role in granulation tissues are most likely to be modulated by cytokines. As these cells are derived from normal fibroblasts, their responses to cytokines are assumed to be similar. Until now, however, the difficulties in obtaining and maintaining normal human wound healing myofibroblasts in vitro have hampered comparison. The present study was designed to determine the effect of TGF-beta 1 and IFN-gamma, two cytokines known to modulate fibroblast morphology, on wound healing myofibroblasts and to compare it to fibroblasts. Morphological and phenotypic changes were followed by light and electron microscopy (stress fibers) and immunofluorescence cytochemistry (alpha-SM actin). Functional parameters such as the capacity to synthesize collagen and collagen gel contraction were studied. Both cytokines induced a strong modification of growth rate and phenotypic and morphological parameters in fibroblasts whereas collagen synthesis was slightly changed. Furthermore, TGF-beta 1 increased contractile capacity of fibroblasts whereas IFN-gamma greatly decreased it. In myofibroblasts, TGF-beta 1 and IFN-gamma did not induce any variation of morphology or growth rate. Interestingly, a strong modulation of functional parameters was observed: collagen synthesis was highly modified and, as for fibroblasts, the contractile capacity was altered. However, inhibition of contraction by IFN-gamma was irreversible in myofibroblasts but not in fibroblasts. These results suggest that fibroblastic cells show modulated responses to cytokines according to their stage of differentiation during wound healing.

Adult↗

PubMed1998

Assessment of rapid morphological changes associated with elevated cAMP levels in human orbital fibroblasts.

Orbital fibroblasts exhibit a phenotype distinct from that of other types of fibroblasts. Addition of prostaglandin E2 (PGE2) to culture medium elicits a dramatic change in orbital fibroblast morphology. That response is mediated through the generation of cAMP. Orbital fibroblasts can generate high levels of PGE2 through induction by proinflammatory cytokines of prostaglandin endoperoxide H synthase-2 (PGHS-2). Here we compare the influence on fibroblast morphology of exogenous PGE2, forskolin, and 8-br-cAMP to that mediated through PGHS-2 induction by a lymphocyte-derived cytokine. Within a few hours, orbital fibroblasts treated with any of these test compounds appear under phase-contrast microscopy to exhibit a stellate morphology. When these changes were assessed quantitatively by electric cell-substrate impedance sensing (ECIS), it became evident that 8-br-cAMP, forskolin, and PGE2 initiated shape changes within 30 min of addition to the culture medium, while effects of the cytokine were first evident after approximately 3.5 h. Dermal fibroblasts failed to respond to any of these compounds with regard to changes in cellular morphology. Analysis of micromotion, manifested as small impedance fluctuations, revealed that orbital fibroblasts treated with 8-br-cAMP exhibit less motion than did untreated cells. These results suggest that orbital fibroblast shape can be altered by several compounds known to alter intracellular cAMP levels. They demonstrate the utility of ECIS in the assessment of very rapid and dynamic cellular events associated with changes in cell morphology.

8-Bromo Cyclic Adenosine Monophosphate↗

PubMed1994

Dynamics of the expression of cytoskeleton components and adherens molecules by fibroblastic cells in alkali-burned and lacerated corneas.

To provide a better understanding of the role of fibroblastic cells during corneal wound-healing, we examined the expression of cytoskeleton components (i.e. smooth muscle alpha-actin (alpha-SMA), vimentin, desmin), adherens molecules (vinculin and talin) and cellular fibronectin in alkali-burned and lacerated rabbit corneas. Alkali-burned and lacerated corneas, which had healed for various periods of time (1 day to 45 days), were excised and subjected to immunohistochemical studies with monoclonal antibodies against alpha-SMA, vimentin, desmin, vinculin, talin and cellular fibronectin. Monoclonal antibody against alpha-SMA reacted with fibroblastic cells in injured corneas but did not react with keratocytes in normal corneas. Anti-desmin antibody did not react with any corneal cells in normal or injured corneas except the muscle cells in the newly-formed capillary of injured corneas. The results indicate that the fibroblastic cells in injured corneas have the characteristics of myofibroblasts. The number of myofibroblasts in granulation tissues increased and peaked within 3 weeks of injury and then declined. Electron microscopy revealed that some fibroblastic cells in the lacerated cornea which had healed for 4 weeks contained dense chromatins. In situ 3'-end labeling with terminal nucleotide transferase indicating that some of the fibroblastic cells contained nicked genomic DNA. These observations imply that apoptosis plays a role in regulating the number of myofibroblasts in the injured corneas. Antibodies against cellular fibronectin, vinculin and talin react with the fibroblastic cells in the injured corneas, but not with the keratocytes of normal corneas. Examination with transmission electron microscopy demonstrated the presence of microtendon and fibronexis associated with fibroblastic cells and the presence of stress fiber within fibroblastic cells. The results indicate that the fibroblastic cells may cause corneal wound contraction, which in turn contributes to the formation of opaque scar tissues.

Animals↗

PubMed2000

Memory of past exposure to the chemokine IL-8 inhibits the contraction of fibroblast-populated collagen lattices.

The inflammatory cytokine makeup of healing wounds helps delineate the phases of the repair process. As an example, during the lag phase (inflammatory phase) of repair, elevated levels of IL-8, a chemokine, participate in the activation and chemotaxis of neutrophils. During the normal proliferative and remodeling phases of repair, IL-8 levels are minimal. Healing burn wounds often have small, open, slow-to-heal areas, which have been shown to contain elevated levels of IL-8. Does a limited exposure of IL-8 to fibroblasts in vitro at the concentrations measured in these unhealed sites cause altered cell behavior? To study this possibility the fibroblast-populated collagen lattice (FPCL) model, an in vitro model of wound contraction, was used to investigate fibroblast response to IL-8. As previously reported, the chronic exposure of fibroblasts to IL-8 at 30 ng/ml within FPCLs significantly inhibited FPCL contraction. Fibroblasts in monolayer culture were incubated with IL-8 for 3 days. In the absence of IL-8, FPCLs were manufactured with these preexposed cells and it was found that FPCL contraction was inhibited. Fibroblasts retained their reduced capacity of reorganizing collagen fibrils when previously exposed to IL-8. Treating fibroblasts in monolayer with IL-8 for only 1 h prior to their incorporation into collagen lattices caused inhibition of FPCL contraction. The speculation is that in vivo open areas in reepithelialized healed burns are the consequence of the local population of fibroblasts having been exposed to elevated levels of IL-8. Such an earlier exposure triggers a memory in this population of fibroblasts that alters their capacity to lay down an extracellular matrix that optimizes the migration of epidermal cells.

Cells, Cultured↗

PubMed1997

Fibroblasts stimulate human ovarian cancer cell invasion and expression of 72-kDa gelatinase A (MMP-2).

OBJECTIVE: The host-tumor interactions and tumor stroma may participate in the regulation of invasive behavior of tumor cells. In order to better understand the human ovarian cancer invasion we explored the possibility that normal fibroblasts could participate in the control of the spread of human ovarian cancer. RESULTS: A 3.5-fold increase (from 2.83 +/- 0.97 to 10.2 +/- 3.43%) in human ovarian cancer cell (Ovcar-3) invasion through a reconstituted basement membrane was noted when normal fibroblasts (CRL 1295) were added to the invasion chambers in conjunction with tumor cells. Conditioned medium from either fibroblasts or Ovcar-3 also enhanced the in vitro invasion of Ovcar-3 by 2- to 2.5-fold (from 2.83 +/- 0.97 to 5.71 +/- 3.5 and to 7.15 +/- 1.2%, respectively) compared to nonstimulated control cells. Zymographic analysis and assays of mRNA for the 72-kDa matrix metalloproteinase (MMP-2) showed that Ovcar-3 cells alone produced very low levels of MMP-2; the expression of this gelatinase was detectable in zymography only with stimulation by incubation of these cells with conditioned media from either fibroblasts or ovarian cancer cells themselves. Interestingly, MMP-2 activity was increased also in fibroblasts when using either ovarian cancer cell-conditioned (to 178 +/- 67%) or fibroblast-conditioned medium (to 215 +/- 61%) and the gene expression for MMP-2 was similarly increased in both fibroblasts and Ovcar-3 cells when using either fibroblast-conditioned medium or ovarian cancer cell-conditioned medium from 1.00 +/- 0.25 to 2.20 +/- 0.50 and 1.86 +/- 0.10 in fibroblasts and from 1.00 +/- 0.26 to 1.60 +/- 0.34 and 2.15 +/- 0.30 in Ovcar-3 cells, respectively. CONCLUSIONS: These results show that interplay between tumor cells and normal cells in the control of invasion and secretion of proteolytic enzymes may involve not only paracrine but also autocrine elements. Thus, such interactions are possible and may play an important role in the spread of cancer.

Cell Communication↗

PubMed1996

Increased proliferation in keloid fibroblasts wounded in vitro.

A keloid is a pathological overgrowth of scar expanding beyond the boundaries of the initiating skin wound. Ultimately, this expansive scar is a result of excess collagen synthesized by fibroblasts within the wound. The processes that lead to this collagen excess remain unknown. An in vitro wound model was developed to test the hypothesis that fibroblasts isolated from keloid tissue and wounded in vitro might proliferate more rapidly that similarly wounded normal dermal fibroblasts. Keloid fibroblasts (KF) and normal human dermal fibroblasts (NDF) were grown to confluence and quiescence in flexible-bottomed culture plates. Wounds were created in a standardized fashion using a specially designed jig. The jig utilized a 25 gauge needle to reproducibly ablate 16-20% of cells from confluent cell sheets. Wounded and nonwounded cells were labeled with 3H-thymidine at 24, 48, 72 and 96 hr postwounding to measure DNA synthesis. Wounded KF and NDF demonstrated increased 3H-thymidine incorporation compared to nonwounded control cultures, and wounded KF demonstrated significantly higher levels of 3H-thymidine incorporation than wounded NDF both 24 and 48 hr after wounding. A similar trend was seen in cell counts. The wounded KF also showed a statistically greater labeling index quantitated by autoradiography than did wounded NDF. The increased commitment to DNA synthesis in response to wounding in vitro in keloid fibroblasts correlates with pathology seen in vivo. Keloid fibroblasts may have a lower inherent threshold for S phase entry than do normal fibroblasts contributing to the increased proliferation of keloid fibroblasts in response to wounding in vitro.

Autoradiography↗

PubMed1999

TGF-beta2 activates proliferative scar fibroblasts.

BACKGROUND: Cytokines, such as the transforming growth factor beta (TGF-beta) isoforms, have been linked to the formation of proliferative scars. This study examines the stimulating effects of exogenous TGF-beta2 on cultured keloid, burn hypertrophic scar, and normal skin fibroblasts and whether such effects can be suppressed with TGF-beta2 antibody. METHODS: In vitro, the fibroblast-populated collagen lattice (FPCL) is used in the evaluation of fibroblast activation by measuring contraction of the lattice over time. Primary cultures of fibroblasts were grown from keloids, burn hypertrophic scars, and normal skin using standard cell culture techniques. TGF-beta2 (10 ng/ml) was added to each of the three types of cell cultures and placed on prefabricated FPCLs. Each was tested against their normal control counterparts. TGF-beta2 antibody (100 ng/ml) was then placed on the TGF-beta2-treated FPCLs. All lattices were allowed to contract and areas were measured for 5 days. RESULTS: Compared to controls, keloid fibroblasts were most affected by the addition of exogenous TGF-beta2. Normal skin fibroblasts did not show a significant increase in contraction early on, yet a significant difference was seen as time progressed. The addition of TGF-beta2 antibody inhibited the function of keloid and burn hypertrophic scar fibroblasts. It also reversed the increased contraction of the TFG-beta2-treated proliferative scar fibroblasts. CONCLUSION: By utilizing an in vitro model, we have demonstrated that TGF-beta2 antibody reverses the increased contraction of FPCLs by proliferative scar fibroblasts treated with TGF-beta2. This points to a possible treatment modality in patients afflicted with this disfiguring problem.

Antibodies↗

PubMed1999

Stromelysin-1-deficient fibroblasts display impaired contraction in vitro.

Targeted disruption of the stromelysin-1 gene in mice causes a delay in excisional wound healing due to a failure in wound contraction. Therefore, we postulated that stromelysin-1 activity is responsible for initiating contraction. To test this hypothesis, we compared the contractile capacity of fibroblasts from stromelysin-1 knockout mice (strom-1 KO) with that of normal fibroblasts using a collagen gel contraction model. Fibroblast cultures were established from explants of skin and lung parenchyma from strom-1 KO and wild-type mice, then transferred to the surface of collagen gels. The extent of contraction was determined by measuring greatest gel diameter. Results demonstrated that (1) all fibroblasts contracted collagen gels in a uniform concentric fashion, (2) skin fibroblasts from both sets of mice exhibited greater gel contraction than did lung fibroblasts, and (3) strom-1 KO fibroblasts demonstrated significantly less contraction (21-23%) than wild-type fibroblasts. These data support the hypothesis that absence of stromelysin-1 results in defective fibroblast contraction that may contribute to delayed wound healing.

Animals↗

PubMed2002

Arsenite disrupts mitosis and induces apoptosis in SV40-transformed human skin fibroblasts.

Chronic ingestion of arsenite-contaminated drinking water causes skin, bladder, and liver cancer. The mechanism of arsenite-induced carcinogenesis is unknown. Arsenite is known to disrupt mitosis and to delay transit through M phase in normal diploid fibroblasts. SV40-transformed human fibroblasts were observed to be hypersensitive to the cytotoxic and cytostatic effects of NaAsO(2) compared with normal diploid fibroblasts in concentration-response experiments. Five to 20 microM NaAsO(2) induced cytostasis in cycling normal diploid fibroblasts but not overt lethality in quiescent normal diploid fibroblasts. High concentrations of arsenite were overtly lethal in both cycling and quiescent cells. The IC50 for cycling SV40-transformed fibroblasts was 3.8 and 4.8 microM for the SV40-transformed lines GM4429 and GM0637, respectively, whereas, in cycling normal diploid fibroblasts (GM0024), the IC50 was 24.7 microM. Microscopic examination of NaAsO(2)-treated SV40-transformed fibroblasts suggested a concentration-dependent accumulation of cells in mitosis undergoing apoptosis. Treatment of SV40-transformed fibroblasts with 0-10 microM NaAsO(2) caused a concentration-dependent inhibition of cell proliferation, accumulation of cells having G2/M DNA contents, and increases in the mitotic index. Phase microscopy, annexin V binding, and electron microscopy demonstrated that arrested mitotic cells underwent apoptosis. These results indicate that SV40-transformation sensitizes cells to arsenite-induced mitotic arrest and induction of apoptosis in the mitotic cells.

Apoptosis↗

PubMed1995

A fibroblast cell line cultured from a hypertrophic scar displays selective downregulation of collagen gene expression: barely detectable messenger RNA levels of the pro alpha 1(III) chain of type III collagen.

The present study was designed to investigate the expression of type I, III and VI collagens by a fibroblast cell line initiated from a hypertrophic scar. The same tissue has previously been demonstrated to display markedly elevated expression of type I and III collagen mRNAs in vivo. Unexpectedly, slot-blot and Northern hybridizations revealed a barely detectable steady-state level of pro alpha 1(III) collagen chain mRNA in cultured hypertrophic scar fibroblasts. The levels of pro alpha 1(I) and alpha 2(VI) collagen chain mRNAs were essentially the same in fibroblasts cultured from hypertrophic scar and in fibroblasts cultured from normal skin. However, Northern blot analyses indicated that the ratio of 5.8 kb to 4.8 kb species of pro alpha 1(I) collagen mRNA was slightly reduced in fibroblasts originating from the hypertrophic scar compared to that in normal fibroblasts. When normal fibroblasts were incubated in conditioned medium from hypertrophic scar cultures, the expression of pro alpha 1(III) collagen chain mRNA decreased to a markedly lower level. Our studies suggest that collagen synthesis by fibroblasts in hypertrophic scars is stimulated by humoral factors which are active only in vivo. Furthermore, the results suggest that fibroblasts cultured from hypertrophic scar display a selective downregulation of different collagen genes and that this downregulation is exerted through an autocrine mechanism.

Adult↗

PubMed1979

Characterization of the subunits of purine nucleoside phosphorylase from cultured normal human fibroblasts.

In previous communications we have demonstrated that the subunits of normal human erythrocyte purine nucleoside phosphorylase can be resolved into four major (1-4) and two minor (1p and 2p) components with the same molecular weight but different apparent isoelectric points (and net ionic charge). The existence of subunits with different charge results in a complex isoelectric focusing pattern of the native erythrocytic enzyme. In contrast, the isoelectric focusing pattern of the native enzyme obtained from cultured human fibroblasts is simpler. The multiple native isoenzymes obtained from human erythrocytes and human brain have isoelectric points ranging from 5.0 to 6.4 and from 5.2 to 5.8 respectively, whereas cultured human fibroblasts have two major native isoenzymes with apparent isoelectric points of 5.1 and 5.6. Purine nucleoside phosphorylase has been purified at least a hundredfold from 35S-labeled cultured human fibroblasts. A two-dimensional electrophoretic analysis of the denatured purified normal fibroblast enzyme revealed that it consists mainly of subunit 1 (90%) with small amounts of subunits 2 (10%) and 3 (1%). This accounts for the observed differences between the native isoelectric focusing and the electrophoretic patterns of the erythrocyte and fibroblast enzymes. The purine nucleoside phosphorylase subunit 1 is detectable in the autoradiogram from a two-dimensional electrophoretic analysis of a crude, unpurified extract of 35S-labeled cultured normal human fibroblasts. The fibroblast phosphorylase coincides with the erythrocytic subunit 1 of the same enzyme, and the cultured fibroblasts of a purine nucleoside phosphorylase deficient patient (patient I) lack this protein component, genetically confirming the identity of the purine nucleoside phosphorylase subunit in cultured fibroblasts.

Apoenzymes↗

PubMed1983

Stromal cell changes in human colorectal adenomas and carcinomas. An ultrastructural study of fibroblasts, myofibroblasts, and smooth muscle cells.

Structural changes in stromal cells during the development of human colorectal carcinomas were studied by light and electron microscopy. The results were as follows: Stromal cells of the lamina propria in control subjects consisted principally of resting fibroblasts. Stromal fibroblasts were mildy activated in adenomas with mild -moderate atypia, and more markedly in adenomas with severe atypia (carcinoma in situ). In invasive adenocarcinomas, (a) desmoplastic reaction was induced, (b) stromal fibroblasts proliferated significantly and were activated showing enlarged nuclei and abundant rough endoplasmic reticulum, and (c) some smooth muscle cells were endowed with well-developed rough endoplasmic reticulum in their axial cytoplasm, resulting in a similar appearance to "myofibroblasts". Stromal fibroblasts in ulcerative colitis and proctitis were also activated. Morphometric analysis revealed that activated fibroblasts significantly increased the areas of their nuclei and cytoplasm, and the perimeter of rough endoplasmic reticulum. These activated fibroblasts suggested a higher production of collagen and other connective tissue proteins. Bundles of microfilaments of actin type were readily found in fibroblasts in all cases examined. These filaments were most remarkable in the fibroblasts in the desmoplastic stroma of invasive adenocarcinoma and were considered to be one of the basic components of these cells. Relationships between fibroblasts, "myofibroblasts", and smooth muscle cells are discussed.

Adenocarcinoma↗

PubMed1996

Role of fibroblasts in the regulation of proinflammatory interleukin IL-1, IL-6 and IL-8 levels induced by keratinocyte-derived IL-1.

In the epidermis, the keratinocytes are the first cells to be encountered by external stimuli and they are able to promote the inflammatory response by increased production and release of various cytokines. In their turn, these cytokines may directly affect the production of proinflammatory cytokines in human dermal fibroblasts. In addition, in both epithelial and mesenchymal cells cytokine production may be modulated by their mutual interaction, and thereby regulate the inflammatory response. The present study aimed to examine the role of fibroblasts in the regulation of proinflammatory IL-1, IL-6 and IL-8 levels induced by keratinocyte-derived IL-1. The data show that in fibroblasts exposed to conditioned media derived from cultures of normal human keratinocytes or squamous carcinoma cells (SCC-4), both the IL-8 and IL-6 mRNA expression as well as protein production were elevated. In addition, it was shown that these effects were induced by IL-1 alpha. The IL-1 alpha-induced increase in IL-8 and IL-6 production, both on the protein level as well as on the mRNA level, were concentration dependent and occurred almost simultaneously. While the induction of IL-6 and IL-8 occurred simultaneously, the IL-6 mRNA remained elevated for longer. In contrast to increased IL-6 and IL-8 production the IL-1 alpha levels markedly decreased upon culturing of fibroblasts in keratinocyte-derived conditioned medium. From internalization experiments it could be concluded that binding of IL-1 to IL-1 receptors, and its subsequent internalization and intracellular degradation is the most likely mechanism involved in the reduction of IL-1 levels by fibroblasts. Comparing the rate of IL-1 reduction in the presence of various cell types indicated that the rate of IL-1 reduction is directly related to the number of IL-1 receptors found on these cell types. In conclusion, these results indicate that the release of IL-1 alpha by activated keratinocytes may act as an inducer of IL-8 and IL-6 production in neighbouring fibroblasts. This may be an important pathway for the amplification of the inflammatory response. The amounts of both cytokines produced by fibroblasts were at least two to three orders of magnitude higher than those produced by keratinocytes, suggesting an important role of fibroblasts in the general inflammatory response. Furthermore, fibroblasts might be involved in turning off this inflammatory response by reducing IL-1 levels, most likely via IL-1 receptor-mediated uptake.

3T3 Cells↗

PubMed1988

Interactions of extracellular collagen and corneal fibroblasts: morphologic and biochemical changes of rabbit corneal cells cultured in a collagen matrix.

Corneal fibroblasts, also known as keratocytes are surrounded by an extracellular matrix of collagen in vivo. To understand the physiology and pathology of these corneal fibroblasts, it is important to study their interactions with this extracellular matrix. We cultured rabbit corneal fibroblasts on tissue culture plastic dishes or in a hydrated collagen gel and compared the changes in morphology and mitotic activity. Corneal fibroblasts on plastic dishes were flattened and widely spread, whereas those in collagen gel became spindle-shaped with long processes. Examination with an electron microscope revealed that the corneal fibroblasts in collagen gel formed gap junctions with neighboring cells. Gap junctions were hardly ever observed between corneal fibroblasts cultured on plastic dishes. Corneal fibroblasts cultured in a collagen matrix showed much less incorporation of [3H]thymidine than did corneal fibroblasts cultured on plastic, and this incorporation decreased with increasing concentration of collagen. Our present results suggest that the morphologic and biochemical characteristics of corneal fibroblasts cultured in collagen gel are different from those cultured on plastic.

Animals↗

PubMed1986

Proteoglycans synthesized by cultured fibroblasts derived from normal and inflamed human gingiva.

The in vitro proliferations rates and proteoglycans synthesized by adult human gingival fibroblasts derived from six age- and sex-matched donors of healthy and chronically inflamed gingiva were analyzed. Fibroblasts from inflamed gingiva demonstrated a slower growth rate than cells from healthy tissue. The rate of incorporation of [35S]sulfate into cell layer-associated proteoglycans and the release of these macromolecules into the culture medium did not differ appreciably between the two groups of cells. Similarly, no detectable differences in the overall charge of the proteoglycans synthesized by normal and inflamed gingival fibroblasts, as assessed by their elution from DEAE-Sephacel, were noted. However, Sepharose CL-4B chromatography revealed that the medium-associated proteoglycans made by the inflamed tissue fibroblasts were depleted in one species of chondroitin sulfate proteoglycans and contained more dermatan sulfate than did control cells. In addition, the intracellular proteoglycan pool was found to be greatly diminished in the inflamed tissue fibroblast cell layers. Glycosaminoglycan analysis of the proteoglycans confirmed these observations. Compared to normal gingival fibroblasts, the inflamed tissue fibroblasts released less heparan sulfate into the medium. Additionally, increased levels of dermatan sulfate and depleted amounts of chondroitin sulfate in the medium of inflamed gingival cells were noted. The observed changes were stable through several transfers in culture and indicate that chronically inflamed tissue may contain fibroblasts manifesting a heritable phenotype differing from fibroblasts in normal connective tissue.

Cell Division↗