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Abstract
Understanding wound healing today involves much more than simply stating that there are three phases: "inflammation, proliferation, and maturation." Wound healing is a complex series of reactions and interactions among cells and "mediators." Each year, new mediators are discovered and our understanding of inflammatory mediators and cellular interactions grows. This article will attempt to provide a concise report of the current literature on wound healing by first reviewing the phases of wound healing followed by "the players" of wound healing: inflammatory mediators (cytokines, growth factors, proteases, eicosanoids, kinins, and more), nitric oxide, and the cellular elements. The discussion will end with a pictorial essay summarizing the wound-healing process.
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Affiliation(s)
- George Broughton
- Department of Plastic Surgery, Nancy L and Perry Bass Advanced Wound Healing Laboratory, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9132, USA.
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Harrison CA, Gossiel F, Bullock AJ, Sun T, Blumsohn A, Mac Neil S. Investigation of keratinocyte regulation of collagen I synthesis by dermal fibroblasts in a simplein vitromodel. Br J Dermatol 2005; 154:401-10. [PMID: 16445767 DOI: 10.1111/j.1365-2133.2005.07022.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND Hypertrophic scarring and skin graft contracture are major causes of morbidity after burn injuries. A prominent feature is excessive fibroplasia with accumulation of increased fibrillar collagen relative to normal scar tissue. The application of split-thickness skin grafts or cultured epithelial autografts to burn wounds is known to reduce scarring and contraction. OBJECTIVES To investigate further how the keratinocyte influences underlying fibroblast behaviour by examining the influence of keratinocytes on fibroblast collagen synthesis, using a new assay for collagen synthesis never previously applied to skin cell biology. METHODS We investigated the influence of the keratinocyte on fibroblast synthesis of type I collagen using an immunoassay for the aminoterminal propeptide of type I collagen (P1NP) in conditioned medium from monocultures and cocultures of keratinocytes and fibroblasts over 14 days. The importance of the physical presence of the keratinocyte was investigated by comparing cocultures of keratinocytes and fibroblasts against fibroblast monocultures with keratinocyte-conditioned medium. Pharmacological agents known to promote fibroblast proliferation [basic fibroblast growth factor (bFGF)], keratinocyte proliferation [insulin-like growth factor (IGF)-1], modify scarring in vivo[tumour necrosis factor (TNF)-alpha] or modify collagen biochemistry [putrescine, estrone, estradiol and beta-aminopropionitrile (beta-APN)] were then investigated for their effect on collagen synthesis in fibroblasts and in keratinocyte/fibroblast cocultures. RESULTS Keratinocytes in coculture with fibroblasts, and keratinocyte-conditioned medium, both reduced fibroblast P1NP synthesis. Of the pharmacological agents investigated, bFGF, IGF-1, TNF-alpha and beta-APN all increased collagen synthesis both in monocultures of fibroblasts and in cocultures of keratinocytes and fibroblasts. CONCLUSIONS Fibroblast collagen synthesis appears to be downregulated by keratinocyte-derived cytokines. Fibroblast growth factors and proinflammatory cytokines appear to be able partially to overcome this downregulation and to increase collagen synthesis.
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Affiliation(s)
- C A Harrison
- Skin Research Group, Division of Clinical Sciences (North), University of Sheffield, UK.
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53
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Otte JM, Boser S, Brunke G, Kiehne K, Schmitz F, Banasiewicz T, Drews M, Schmidt WE, Herzig KH. Expression of keratinocyte growth factor and its receptor in adaptive changes of ileorectal pouch mucosa. Scand J Gastroenterol 2005; 40:1066-75. [PMID: 16211713 DOI: 10.1080/00365520510023756] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
OBJECTIVE Total proctocolectomy with formation of an ileo-anal pouch is a well-established surgical procedure for patients with ulcerative colitis (UC) or familiar adenomatous polyposis (FAP). The pouch mucosa undergoes adaptive changes, with inflammation of the ileal reservoir being the most common complication. The aetiology is unknown. The keratinocyte growth factor (KGF) has not only been shown to promote intestinal wound healing and re-epithelialization but also to have some immunomodulatory properties. This study was designed to investigate a putative involvement of KGF in observed histomorphological changes in the pouch mucosa. MATERIALS AND METHODS Multiple biopsies were obtained from age-matched and sex-matched patients. Biopsies were stained with H&E and scored for inflammation and morphological changes. mRNA expression levels of KGF and KGF-receptor (KGFR) were determined using competitive RT-PCR, protein expression and phosphorylation was analyzed by Western blotting. KGF and KGFR were localized in tissue samples by immunohistochemistry. RESULTS Expression of KGF and KGFR was significantly increased in inflamed and adapting mucosa. Patterns of expression did not significantly differ in pouch mucosa from UC or FAP patients. Protein expression correlated with the mRNA results and KGFR was shown to be activated in adapting pouch mucosa. KGF was detected on subepithelial cells, mainly on fibroblasts, whereas expression of KGFR was restricted to epithelial cells. CONCLUSION Expression of KGF and KGFR is significantly increased in the pouch mucosa, suggesting an involvement of this growth factor in tissue repair and adaptive changes. Topical application of KGF might alleviate the inflammatory and promote the adaptive process in the ileo-anal pouch mucosa.
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Affiliation(s)
- Jan-Michel Otte
- Department of Medicine, St. Josef Hospital, Ruhr-University Bochum, Germany
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54
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Finch PW, Rubin JS. Keratinocyte growth factor/fibroblast growth factor 7, a homeostatic factor with therapeutic potential for epithelial protection and repair. Adv Cancer Res 2004; 91:69-136. [PMID: 15327889 DOI: 10.1016/s0065-230x(04)91003-2] [Citation(s) in RCA: 170] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Keratinocyte growth factor (KGF) is a paracrine-acting, epithelial mitogen produced by cells of mesenchymal origin. It is a member of the fibroblast growth factor (FGF) family, and acts exclusively through a subset of FGF receptor isoforms (FGFR2b) expressed predominantly by epithelial cells. The upregulation of KGF after epithelial injury suggested it had an important role in tissue repair. This hypothesis was reinforced by evidence that intestinal damage was worse and healing impaired in KGF null mice. Preclinical data from several animal models demonstrated that recombinant human KGF could enhance the regenerative capacity of epithelial tissues and protect them from a variety of toxic exposures. These beneficial effects are attributed to multiple mechanisms that collectively act to strengthen the integrity of the epithelial barrier, and include the stimulation of cell proliferation, migration, differentiation, survival, DNA repair, and induction of enzymes involved in the detoxification of reactive oxygen species. KGF is currently being evaluated in clinical trials to test its ability to ameliorate severe oral mucositis (OM) that results from cancer chemoradiotherapy. In a phase 3 trial involving patients who were treated with myeloablative chemoradiotherapy before autologous peripheral blood progenitor cell transplantation for hematologic malignancies, KGF significantly reduced both the incidence and duration of severe OM. Similar investigations are underway in patients being treated for solid tumors. On the basis of its success in ameliorating chemoradiotherapy-induced OM in humans and tissue damage in a variety of animal models, additional clinical applications of KGF are worthy of investigation.
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Affiliation(s)
- Paul W Finch
- Laboratory of Cellular and Molecular Biology, National Cancer Institute, Bethesda, Maryland 20892, USA
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55
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Abstract
Growth substances (cytokines and growth factors) are soluble signaling proteins affecting the process of normal wound healing. Cytokines govern the inflammatory phase that clears cellular and extracellular matrix debris. Wound repair is controlled by growth factors (platelet-derived growth factor [PDGF], keratinocyte growth factor, and transforming growth factor beta). Endogenous growth factors communicate across the dermal-epidermal interface. PDGF is important for most phases of wound healing. Becaplermin (PDGF-BB), the only growth factor approved by the Food and Drug Administration, requires daily application for neuropathic wound healing. Gene therapy is under development for more efficient growth factor delivery; a single application will induce constitutive growth factor expression for weeks. Based on dramatic preclinical animal studies, a phase 1 clinical trial planned on a PDGF genetic construct appears promising.
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Affiliation(s)
- Robert Goldman
- Department of Rehabilitation Medicine, University of Pennsylvania, Philadelphia, USA
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56
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Putnins EE, Sanaie AR, Wu Q, Firth JD. Induction of keratinocyte growth factor 1 Expression by lipopolysaccharide is regulated by CD-14 and toll-like receptors 2 and 4. Infect Immun 2002; 70:6541-8. [PMID: 12438323 PMCID: PMC132971 DOI: 10.1128/iai.70.12.6541-6548.2002] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Periodontal disease is a chronic inflammatory condition that is associated with increased concentrations of gram-negative pathogenic bacteria and epithelial cell proliferation. Regulation of this proliferation is poorly understood but is most likely controlled by locally expressed growth factors. Keratinocyte growth factor 1, an epithelium-specific growth factor, is expressed by gingival fibroblasts, and its expression is regulated in a concentration-dependent manner by lipopolysaccharide. In this study, induction of keratinocyte growth factor 1 protein expression was dependent on gingival fibroblast expression of membrane CD14 (mCD14) and Toll-like receptors 2 and 4. Lipopolysaccharides from Escherichia coli and Porphyromonas gingivalis induced membrane expression of CD14 at 1, 3, and 24 h. Specifically, lipopolysaccharide induced low mCD14 expression gingival fibroblasts to express mCD14 at a level consistent with that of high mCD14 expression cells. Functional studies with specific blocking antibodies for CD14 and Toll-like receptors 2 and 4 implicated all of these molecules in signal transduction. The rapid decrease in cell membrane expression of Toll-like receptors 2 and 4 after treatment with lipopolysaccharide was consistent with receptor internalization, and blocking of either of these receptors completely inhibited keratinocyte growth factor 1 protein expression. The transcription factors AP-1 and NF-kappaB were involved in lipopolysaccharide induction of keratinocyte growth factor 1 mRNA and protein expression. These results suggest that lipopolysaccharide may induce proliferation of periodontal epithelial cells by upregulating keratinocyte growth factor 1 expression via the CD14 and Toll-like receptor signaling pathway.
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Affiliation(s)
- Edward E Putnins
- Department of Oral Biological and Medical Sciences University of British Columbia, Vancouver, Canada.
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57
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Saarialho-Kere U, Kerkelä E, Jahkola T, Suomela S, Keski-Oja J, Lohi J. Epilysin (MMP-28) expression is associated with cell proliferation during epithelial repair. J Invest Dermatol 2002; 119:14-21. [PMID: 12164918 DOI: 10.1046/j.1523-1747.2002.01790.x] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Epilysin (MMP-28) is the newest member of the matrix metalloproteinase enzyme family. Several members of this enzyme family have been associated with various aspects of wound repair and cancer invasion. The aim of this study was to characterize in different types of wounds, skin cancers, and keratinocyte cultures factors that contribute to epilysin expression in vivo, as well as how and where it is induced in relation to other matrix metalloproteinases. Our results indicate that epilysin is produced by the mitotic Ki-67-positive keratinocytes distal from the wound edge in both acute and chronic wounds and that it does not generally colocalize with collagenase-1, stromelysin-2, or 92 kDa gelatinase in migrating keratinocytes. An injury of epidermis was needed for epilysin induction as it was upregulated in ulcerated pyogenic granulomas and in suction blisters but was not detected in intact acanthotic or normal skin. Unlike many other matrix metalloproteinases, epilysin was not detected in the invading cancer cell nests of sclerosing basal or squamous cell cancers of various grades. When primary keratinocytes were stimulated with tumor necrosis factor alpha, upregulation of epilysin mRNA was evident within 24-48 h as measured by quantitative reverse transcription polymerase chain reaction. In primary keratinocyte, HaCaT, and A431 carcinoma cell cultures none of the 10 other growth factors or extracellular matrices studied were able to upregulate epilysin expression. Our results suggest that epilysin expression is tightly spatially and temporally regulated during wound repair. Although the in vivo substrates of epilysin are not known at present, its expression pattern suggests that it may be needed to restructure the basement membrane or to degrade adhesive proteins between keratinocytes to supply new cells for the migrating front.
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Affiliation(s)
- Ulpu Saarialho-Kere
- Department of Dermatology, Biomedicum Helsinki, University Central Hospital, University of Helsinki, Meilahdentie 2, 00250 Helsinki, Finland.
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58
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Ware LB, Matthay MA. Keratinocyte and hepatocyte growth factors in the lung: roles in lung development, inflammation, and repair. Am J Physiol Lung Cell Mol Physiol 2002; 282:L924-40. [PMID: 11943656 DOI: 10.1152/ajplung.00439.2001] [Citation(s) in RCA: 218] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
A growing body of evidence indicates that the epithelial-specific growth factors keratinocyte growth factor (KGF), fibroblast growth factor (FGF)-10, and hepatocyte growth factor (HGF) play important roles in lung development, lung inflammation, and repair. The therapeutic potential of these growth factors in lung disease has yet to be fully explored. KGF has been best studied and has impressive protective effects against a wide variety of injurious stimuli when given as a pretreatment in animal models. Whether this protective effect could translate to a treatment effect in humans with acute lung injury needs to be investigated. FGF-10 and HGF may also have therapeutic potential, but more extensive studies in animal models are needed. Because HGF lacks true epithelial specificity, it may have less potential than KGF and FGF-10 as a targeted therapy to facilitate lung epithelial repair. Regardless of their therapeutic potential, studies of the unique roles played by these growth factors in the pathogenesis and the resolution of acute lung injury and other lung diseases will continue to enhance our understanding of the complex pathophysiology of inflammation and repair in the lung.
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Affiliation(s)
- Lorraine B Ware
- Division of Pulmonary and Critical Care, Department of Medicine, University of California, Los Angeles 90024, USA
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59
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Nasu K, Arima K, Fujisawa K, Nishida M, Kai K, Miyakawa I. Secretion of keratinocyte growth factor by cultured human endometrial stromal cells is induced through a cyclic adenosine monophosphate-dependent pathway. Fertil Steril 2002; 77:392-5. [PMID: 11821103 DOI: 10.1016/s0015-0282(01)02975-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
OBJECTIVE To evaluate the effects of known modulators of endometrial function on the production of keratinocyte growth factor by endometrial stromal cells. DESIGN The effects of dibutyryl-cyclic adenosine monophosphate (db-cAMP), 12-O-tetradecanoylphorbol 13-acetate (TPA), ethinyl estradiol-17alpha (EE), and medroxyprogesterone acetate (MPA) on the secretion of keratinocyte growth factor by endometrial stromal cells were investigated. SETTING Research laboratory at a university medical school. PATIENT(S) Eleven endometrial specimens in the late proliferative phase. INTERVENTION(S) Endometrial stromal cells were incubated for 24 hours with db-cAMP, TPA, EE, or MPA. MAIN OUTCOME MEASURE(S) The concentration of keratinocyte growth factor in the culture media was measured using an ELISA. RESULT(S) Small amounts of keratinocyte growth factor were detected in the culture media of unstimulated endometrial stromal cells. The production of keratinocyte growth factor by endometrial stromal cells was stimulated with db-cAMP in a dose-dependent manner. The stimulatory effect of db-cAMP was inhibited by Rp-adenosine 3',5'-cyclic monophosphothioate. None of TPA, EE, nor MPA affected the keratinocyte growth factor production by these cells. CONCLUSION(S) These results suggest that a cAMP-dependent pathway may play an important role in the regulation of keratinocyte growth factor production by endometrial stromal cells. Keratinocyte growth factor secreted by endometrial stromal cells may be involved in the regeneration of the endometrium during the normal menstrual cycle and early pregnancy.
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Affiliation(s)
- Kaei Nasu
- Department of Obstetrics and Gynecology, Oita Medical University, Hasama-machi, Oita 879-5593, Japan.
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60
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Elias PM, Ghadially R. The aged epidermal permeability barrier: basis for functional abnormalities. Clin Geriatr Med 2002; 18:103-20, vii. [PMID: 11913735 DOI: 10.1016/s0749-0690(03)00037-5] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Aged epidermis develops an abnormality in permeability barrier homeostasis, which is accentuated further in photoaged skin. The biochemical basis is a global reduction in stratum corneum lipids and profound abnormality in cholesterol synthesis. Various cytokine/growth factor signaling pathways are abnormal in aged skin, particularly in the interleukin-1 family. Barrier repair therapy can be effective in restoring normal function if a cholesterol-dominant mixture of the three key physiologic lipids, including ceramides and free fatty acids, is emphasized.
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Affiliation(s)
- Peter M Elias
- Department of Dermatology, University of California, San Francisco, USA.
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61
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Giri D, Ittmann M. Interleukin-1alpha is a paracrine inducer of FGF7, a key epithelial growth factor in benign prostatic hyperplasia. THE AMERICAN JOURNAL OF PATHOLOGY 2000; 157:249-55. [PMID: 10880394 PMCID: PMC1850193 DOI: 10.1016/s0002-9440(10)64535-x] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Benign prostatic hyperplasia (BPH) is an extremely common disease of older men in which there is benign overgrowth of the prostatic transition zone, leading to obstruction of urine outflow. FGF7, a potent growth factor for prostatic epithelial cells, is increased by threefold in BPH and is correlated with increased epithelial proliferation in this condition. Immunohistochemistry of normal and hyperplastic prostate revealed that FGF7-expressing fibroblastic cells were present in higher numbers near the epithelial acini, implying that epithelial cells may express a factor that induces FGF7 expression by stromal cells. Conditioned medium (CM) from primary cultures of prostatic epithelial cells was capable of inducing a two- to sixfold increase in the expression of FGF7 by primary stromal cultures. Blocking experiments with neutralizing anti-interleukin-1alpha (Il-1alpha) antibodies and IL-1Ra, an Il-1alpha receptor antagonist, show that this inducing activity was due to the presence of Il-1alpha in the epithelial CM. Analysis of normal prostatic peripheral zone and BPH tissue by enzyme-linked immunoabsorption assay reveal that Il-1alpha is present at increased levels in hyperplastic prostate and that levels of Il-1alpha correlate strongly with tissue FGF7 concentration in BPH. Therefore Il-1alpha is produced by prostatic epithelial cells and can induce FGF7, a potent epithelial growth factor, which can in turn lead to further epithelial growth and increased Il-1alpha secretion, thus establishing a double paracrine loop that is functionally equivalent to an autocrine growth loop. This double paracrine loop may play a key role in the abnormal proliferation of the transition zone, which is critical to the pathogenesis of BPH.
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Affiliation(s)
- D Giri
- Department of Pathology, Baylor College of Medicine, Houston, TX 77030, USA
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62
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Otte JM, Schmitz F, Banasiewicz T, Drews M, Fölsch UR, Herzig KH. Expression of keratinocyte growth factor and its receptor in colorectal cancer. Eur J Clin Invest 2000; 30:222-9. [PMID: 10691999 DOI: 10.1046/j.1365-2362.2000.00617.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND AND AIMS The mesenchymal derived keratinocyte growth factor stimulates growth, differentiation and migration of intestinal epithelial cells. In the human gastrointestinal tract an overexpression of this growth factor has been reported in inflammatory bowel disease and pancreatic cancer. In the present study we investigated expression patterns of keratinocyte growth factor and receptor in normal and neoplastic colonic mucosa and in metastases. Furthermore, biological effects on normal intestinal and colorectal cancer cell lines were determined. MATERIALS AND METHODS Expression patterns were analysed at the mRNA level by reverse transcription-polymerase chain reaction (RT-PCR) and at the protein level by Western blotting. Localization of ligand and receptor in normal intestinal mucosa and cancer tissue was investigated by immunohistochemistry. Mitogenic effects of keratinocyte growth factor were assayed by [3H]thymidine incorporation in normal (Intestine-407, IEC-6, IEC-18) and colorectal cancer cell lines (Colo320, LoVo, SW403, SW707). RESULTS mRNA expression of keratinocyte growth factor and receptor was detected in the majority of normal and cancer samples without significant alterations. At the protein level keratinocyte growth factor expression did not differ between normal and malignant specimens, whereas protein expression of the receptor was increased up to twofold in well- to moderately differentiated colorectal cancers. DNA synthesis was significantly stimulated by keratinocyte growth factor in all three normal intestinal cell lines, whereas this growth factor did not significantly alter the [3H]thymidine incorporation in the colorectal cancer cell lines. CONCLUSION Keratinocyte growth factor and its receptor were detected in the majority of samples from normal and neoplastic colonic mucosa, with an overexpression of the receptor seen in the more differentiated tumour samples. Keratinocyte growth factor is a strong mitogen for normal intestinal cells, whereas it is less effective in neoplastic cells.
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Affiliation(s)
- J M Otte
- Christian-Albrechts-Universität, Kiel, Germany; Karol Marcinowski University, Poznan, Poland
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63
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Mansbridge JN, Liu K, Pinney RE, Patch R, Ratcliffe A, Naughton GK. Growth factors secreted by fibroblasts: role in healing diabetic foot ulcers. Diabetes Obes Metab 1999; 1:265-79. [PMID: 11225638 DOI: 10.1046/j.1463-1326.1999.00032.x] [Citation(s) in RCA: 114] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- J N Mansbridge
- Advanced Tissue Sciences, Inc., La Jolla, CA 92037, USA.
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64
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Charafeddine L, D'Angio CT, Richards JL, Stripp BR, Finkelstein JN, Orlowski CC, LoMonaco MB, Paxhia A, Ryan RM. Hyperoxia increases keratinocyte growth factor mRNA expression in neonatal rabbit lung. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 276:L105-13. [PMID: 9887062 DOI: 10.1152/ajplung.1999.276.1.l105] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Acute hyperoxic lung injury remains a major factor in the development of chronic lung disease in neonates. A critical step in the repair of acute lung injury is the proliferation of type II alveolar epithelial cells. Type II cell proliferation is stimulated by keratinocyte growth factor (KGF), an epithelial cell-specific mitogen. We sought to investigate KGF mRNA expression in relation to type II cell proliferation during hyperoxic lung injury. We studied a previously described newborn (NB) rabbit model of acute and chronic hyperoxic injury [C. T. D'Angio, J. N. Finkelstein, M. B. LoMonaco, A. Paxhia, S. A. Wright, R. B. Baggs, R. H. Notter, and R. M. Ryan. Am. J. Physiol. 272 (Lung Cell. Mol. Physiol. 16): L720-L730, 1997]. NB rabbits were placed in 100% O2 for 9 days and then recovered in 60% O2. RT-PCR was used to synthesize and amplify a 267-bp fragment of rabbit KGF cDNA from whole lung RNA. KGF mRNA expression was analyzed by ribonuclease protection assay, and mRNA abundance was quantified by phosphorimaging. Proliferating cell nuclear antigen immunohistochemistry was used on lung sections to identify proliferating cells. The rabbit partial cDNA sequenced was >95% homologous to human cDNA, and all amino acids were conserved. Whole lung KGF mRNA expression was increased 12-fold after 6 days of hyperoxia compared with control lungs, and remained increased throughout the 100% O2 exposure period. Proliferating cell nuclear antigen immunohistochemistry showed an increase in type II cell proliferation after 8-12 days of hyperoxia. NB rabbits exposed to hyperoxic injury exhibit increased whole lung KGF mRNA expression preceding type II cell proliferation. KGF may be an important mitogen in the regulation of alveolar epithelial repair after hyperoxic lung injury.
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Affiliation(s)
- L Charafeddine
- Department of Pediatrics, Strong Children's Research Center, University of Rochester, Rochester, New York 14642, USA
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65
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Abstract
Keratinocyte growth factor (KGF) is a member of the rapidly growing fibroblast growth factor (FGF) family of mitogens. Whereas most FGFs influence proliferation and/or differentiation of various cell types, KGF seems to act specifically on epithelial cells. It has been demonstrated that KGF stimulates proliferation and migration of these cells, but it also affects differentiation processes. Finally, recent studies have demonstrated a protective function of this growth factor in vitro and in vivo. Due to these properties, KGF could play an important role in repair processes. Indeed a series of studies have provided insight into the expression and function of KGF in inflammation and repair of various tissues and organs, and a therapeutic potential of this growth factor has been demonstrated.
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Affiliation(s)
- S Werner
- Max-Planck-Institut für Biochemie, Martinsried, Germany.
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66
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Casey ML, MacDonald PC. Keratinocyte growth factor expression in the mesenchymal cells of human amnion. J Clin Endocrinol Metab 1997; 82:3319-23. [PMID: 9329361 DOI: 10.1210/jcem.82.10.4294] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Amnion epithelial and mesenchymal cells were separated by differential protease treatment, and the separated cells were maintained in monolayer culture. Keratinocyte growth factor (KGF) messenger RNA (mRNA) was readily detected by Northern analysis of amnion mesenchymal cell total RNA (10 micrograms) but not in amnion epithelial cells. Treatment of the amnion mesenchymal cells in serum-free medium with tetradecanoyl phorbol acetate (1 nM) caused an increase in the level of KGF mRNA. Forskolin treatment also caused an increase in KGF mRNA but not to the levels attained with tetradecanoyl phorbol acetate treatment. Dexamethasone (1 nM) treatment of these cells effected a reduction in the level of KGF mRNA. Prolonged maintenance of mesenchymal cells in serum-free medium also was associated with an increase in the level of KGF mRNA. Treatment with a variety of other agents, viz., interleukin (IL)-1, IL-6 plus or minus IL-6 soluble receptor, IL-11, oncostatin M, epidermal growth factor (EGF), and transforming growth factor-beta and not modify the level of KGF mRNA. Treatment of amnion epithelial cells with KGF caused an increase in the rate of [3H]thymidine incorporation, but the rate of cell replication induced by KGF was less than that induced by treatment with EGF. Transforming growth factor-beta treatment inhibited basal and EGF- and KGF-stimulated amnion epithelial cell replication. The findings of this study are indicative the KGF is expressed in human amnion mesenchymal cells, and that KGF may act on the epithelial cells of this tissue.
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Affiliation(s)
- M L Casey
- Cecil H. and Ida Green Center for Reproductive Biology Sciences, University of Texas Southwestern Medical School, Dallas 75335, USA.
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