Inhibition of fibroblast chemotaxis by recombinant human interferon gamma and interferon alpha

Cytokine and anti-cytokine therapies in prevention or treatment of fibrosis in IBD

The frequency of fibrosing Crohn's disease (CD) is significant, with approximately 40% of CD patients with ileal disease developing clinically apparent strictures throughout their lifetime. Although strictures may be subdivided into fibrotic, inflammatory, or mixed forms, despite immunosuppressive therapy in CD patients in the form of steroids or immunomodulators, the frequency of fibrostenosing complications has still remained significant. A vast number of genetic and epigenetic variables are thought to contribute to fibrostenosing disease, including those that affect cytokine biology, and therefore highlight the complexity of disease, but also shed light on targetable pathways. Exclusively targeting fibrosis may be difficult, however, because of the relatively slow evolution of fibrosis in CD, and the potential adverse effects of inhibiting pathways involved in tissue repair and mucosal healing. Acknowledging these caveats, cytokine-targeted therapy has become the mainstay of treatment for many inflammatory conditions and is being evaluated for fibrotic disorders. The question of whether anti-cytokine therapy will prove useful for intestinal fibrosis is, therefore, acutely relevant. This review will highlight some of the current therapeutics targeting cytokines involved in fibrosis.

Computational Modeling of Inflammation and Wound Healing

OBJECTIVE

Inflammation is both central to proper wound healing and a key driver of chronic tissue injury via a positive-feedback loop incited by incidental cell damage. We seek to derive actionable insights into the role of inflammation in wound healing in order to improve outcomes for individual patients.

APPROACH

To date, dynamic computational models have been used to study the time evolution of inflammation in wound healing. Emerging clinical data on histo-pathological and macroscopic images of evolving wounds, as well as noninvasive measures of blood flow, suggested the need for tissue-realistic, agent-based, and hybrid mechanistic computational simulations of inflammation and wound healing.

INNOVATION

We developed a computational modeling system, Simple Platform for Agent-based Representation of Knowledge, to facilitate the construction of tissue-realistic models.

RESULTS

A hybrid equation-agent-based model (ABM) of pressure ulcer formation in both spinal cord-injured and -uninjured patients was used to identify control points that reduce stress caused by tissue ischemia/reperfusion. An ABM of arterial restenosis revealed new dynamics of cell migration during neointimal hyperplasia that match histological features, but contradict the currently prevailing mechanistic hypothesis. ABMs of vocal fold inflammation were used to predict inflammatory trajectories in individuals, possibly allowing for personalized treatment.

CONCLUSIONS

The intertwined inflammatory and wound healing responses can be modeled computationally to make predictions in individuals, simulate therapies, and gain mechanistic insights.

Role of GTP binding, isoprenylation, and the C-terminal α-helices in the inhibition of cell spreading by the interferon-induced GTPase, mouse guanylate-binding protein-2

Interferon-γ pre-exposure inhibits Rac activation by either integrin engagement or platelet-derived growth factor treatment. Interferon-γ does this by inducing expression of the large guanosine triphosphatase (GTPase) mouse guanylate-binding protein (mGBP-2). Inhibiting Rac results in the retardation of cell spreading. Analysis of variants of mGBP-2 containing amino acid substitutions in the guanosine triphosphate (GTP) binding domain suggests that GTP binding, and possibly dimerization, of mGBP-2 is necessary to inhibit cell spreading. However, isoprenylation is also required. Removal of the N-terminal GTP-binding globular domain from mGBP-2 yields a protein with only the extended C-terminal α-helices that lacks enzymatic activity. The ability of the C-terminal α-helices alone to inhibit cell spreading suggests that this is the domain that interacts with the downstream effectors of mGBP-2. Interestingly, mGBP-2 can inhibit cell spreading whether it is geranylgeranylated or farnesylated. This study begins to define the properties of mGBP-2 responsible for inhibiting cell spreading.

The interferon-gamma-induced murine guanylate-binding protein-2 inhibits rac activation during cell spreading on fibronectin and after platelet-derived growth factor treatment: role for phosphatidylinositol 3-kinase

Exposure of cells to certain cytokines can alter how these same cells respond to later cues from other agents, such as extracellular matrix or growth factors. Interferon (IFN)-gamma pre-exposure inhibits the spreading of fibroblasts on fibronectin. Expression of the IFN-gamma-induced GTPase murine guanylate-binding protein-2 (mGBP-2) can phenocopy this inhibition and small interfering RNA knockdown of mGBP-2 prevents IFN-gamma-mediated inhibition of cell spreading. Either IFN-gamma treatment or mGBP-2 expression inhibits Rac activation during cell spreading. Rac is required for cell spreading. mGBP-2 also inhibits the activation of Akt during cell spreading on fibronectin. mGBP-2 is incorporated into a protein complex containing the catalytic subunit of phosphatidylinositol 3-kinase (PI3-K), p110. The association of mGBP-2 with p110 seems important for the inhibition of cell spreading because S52N mGBP-2, which does not incorporate into the protein complex with p110, is unable to inhibit cell spreading. PI3-K activation during cell spreading on fibronectin was inhibited in the presence of mGBP-2. Both IFN-gamma and mGBP-2 also inhibit cell spreading initiated by platelet-derived growth factor treatment, which is also accompanied by inhibition of Rac activation by mGBP-2. This is the first report of a novel mechanism by which IFN-gamma can alter how cells respond to subsequent extracellular signals, by the induction of mGBP-2.

Molecular dissection of abnormal wound healing processes resulting in keloid disease

Keloids are locally aggressive scars that typically invade into healthy surrounding skin and cause both physical and psychosocial distress to the patient. These pathological scars occur following minimal skin trauma after a variety of causes including burns and trauma. Although the pathogenesis of keloid disease is not well understood, it is considered to be the end product of an abnormal healing process. The aim of this review was to investigate the molecular and cellular pathobiology of keloid disease in relation to the normal wound healing process. The molecular aberrances in keloids that correlate with the molecular mechanisms in normal wound healing can be categorized into three groups: (1) extracellular matrix proteins and their degradation, (2) cytokines and growth factors, and (3) apoptotic pathways. With respect to cellular involvements, fibroblasts are the most well-studied cell population. However, it is unclear whether the fibroblast is the causative cell; they are modulated by other cell populations in wound repair, such as keratinocytes and macrophages. This review presents a detailed account of individual phases of the healing process and how they may potentially be implicated in aberrant raised scar formation, which may help in clarifying the mechanisms involved in keloid disease pathogenesis.

Inflammation modulates fibronectin isoform expression in colonic lamina propria fibroblasts (CLPF)

BACKGROUND

Migration of colonic lamina propria fibroblasts (CLPF) plays an important role during mucosal wound healing as well as fibrosis and fistula formation in Crohn's disease (CD). Recently, we showed that the migratory potential of CD-CLPF was significantly reduced compared to control CLPF. Fistula-derived CD-CLPF migrated less and fibrosis-CLPF more than CLPF from inflamed CD mucosa. These changes in migratory behavior were associated with changes in production of the migration-inducing fibronectin (FN) isoforms ED-A and ED-B. A permanent reduction of the migratory potential of CLPF was mediated by IFN-gamma and tumor necrosis factor (TNF) modulate FN isofom expression in CLPF and thereby might regulate CLPF migration.

MATERIALS AND METHODS

Control CLPF were incubated for 72 h with IFN-gamma, TNF, IFN-gamma plus TNF, or TGF-beta1. Messenger RNA (mRNA) was isolated and expression of FN and isoforms ED-A and ED-B was quantified by real-time polymerase chain reaction. FN, ED-A, and ED-B were investigated by Western blotting. FN receptor integrin alpha5beta1 was analyzed by FACS.

RESULTS

No difference was found for the surface display of integrin alpha5beta1 between stimulated and non-stimulated cells. In TGF-beta1 incubated CLPF mRNA amount of FN and isoforms ED-A and ED-B was slightly increased. IFN-gamma only decreased FN in CLPF, TNF significantly reduced FN-mRNA by 40%, FN ED-A mRNA by 25%, and ED-B mRNA by 50%. The TNF-mediated mRNA downregulation resulted in a decreased protein amount as revealed by Western blotting.

CONCLUSION

Cytokines such as IFN-gamma, TNF, and TGF-beta1 modulate the production of fibronectin isoforms. Our data indicate that inflammation-induced modulation of FN-isoform production is involved in the alterations of migratory potential of CLPF isolated from CD mucosa.

Agent-based model of inflammation and wound healing: insights into diabetic foot ulcer pathology and the role of transforming growth factor-beta1

Inflammation and wound healing are inextricably linked and complex processes, and are deranged in the setting of chronic, nonhealing diabetic foot ulcers (DFU). An ideal therapy for DFU should both suppress excessive inflammation while enhancing healing. We reasoned that biological simulation would clarify mechanisms and help refine therapeutic approaches to DFU. We developed an agent-based model (ABM) capable of reproducing qualitatively much of the literature data on skin wound healing, including changes in relevant cell populations (macrophages, neutrophils, fibroblasts) and their key effector cytokines (tumor necrosis factor-alpha [TNF], interleukin [IL]-1beta, IL-10, and transforming growth factor [TGF]-beta1). In this simulation, a normal healing response results in tissue damage that first increases (due to wound-induced inflammation) and then decreases as the collagen levels increase. Studies by others suggest that diabetes and DFU are characterized by elevated TNF and reduced TGF-beta1, although which of these changes is a cause and which one is an effect is unclear. Accordingly, we simulated the genesis of DFU in two ways, either by (1) increasing the rate of TNF production fourfold or (2) by decreasing the rate of TGF-beta1 production 67% based on prior literature. Both manipulations resulted in increased inflammation (elevated neutrophils, TNF, and tissue damage) and delayed healing (reduced TGF-beta1 and collagen). Our ABM reproduced the therapeutic effect of platelet-derived growth factor/platelet releasate treatment as well as DFU debridement. We next simulated the expected effect of administering (1) a neutralizing anti-TNF antibody, (2) an agent that would increase the activation of endogenous latent TGF-beta1, or (3) latent TGF-beta1 (which has a longer half-life than active TGF-beta1), and found that these therapies would have similar effects regardless of the initial assumption of the derangement that underlies DFU (elevated TNF vs. reduced TGF-beta1). In silico methods may elucidate mechanisms of and suggest therapies for aberrant skin healing.

Cytokine alterations in lichen sclerosus: an immunohistochemical study

BACKGROUND

Although the histology of lichen sclerosus is characteristic, the precise nature of the inflammatory changes and the signals provoking them is uncertain.

OBJECTIVES

To delineate the inflammatory changes in lichen sclerosus more accurately by studying cytokine changes.

METHODS

An immunohistochemical study of 12 specimens of genital lichen sclerosus and one specimen of extragenital lichen sclerosus was undertaken using monoclonal antibodies to interferon (IFN)-gamma, IFN-gamma receptor, tumour necrosis factor (TNF)-alpha, interleukin (IL)-1alpha, IL-2 receptor (CD25), intercellular adhesion molecule-1 (ICAM-1) and its ligand CD11a. Control specimens were seven specimens of normal vulva obtained during gynaecological procedures, three specimens of normal skin, adjacent uninvolved thigh from three of the patients with lichen sclerosus, five specimens of nonvulval psoriasis, four specimens of nonvulval lichen planus and two specimens from chronic wounds.

RESULTS

The lichen sclerosus specimens demonstrated slightly increased staining for IFN-gamma within the epidermis compared with the normal vulva and nonvulval skin. There was increased dermal staining for IFN-gamma both within the pale zone of the upper dermis and within the inflammatory zone below this. We confirmed our previous demonstration that in lichen sclerosus HLA-DR immunostaining is increased in association with vascular endothelium, the inflammatory cell infiltrate and around the keratinocytes. The areas of the epidermis with the strongest immunostaining for HLA-DR generally also had the strongest staining for IFN-gamma. In the lichen sclerosus specimens the zone of inflammation also demonstrated increased immunostaining for TNF-alpha, IL-1alpha, IFN-gamma receptor, CD25, CD11a and ICAM-1 while the zone of sclerosus demonstrated a smaller increase in immunostaining for IFN-gamma receptor, TNF-alpha, CD11a and ICAM-1, and the epidermis demonstrated increased staining for ICAM-1.

CONCLUSIONS

The increased staining for IFN-gamma, TNF-alpha, IL-1alpha, IFN-gamma receptor, CD25, CD11a and ICAM-1 suggest that the cytokine response in lichen sclerosus shares characteristics of the cytokine response in lichen planus and chronic wounds.

Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, and usually fatal pulmonary disease for which there are no proven drug therapies. Anti-inflammatory and immunosuppressive agents have been largely ineffective. The precise relationship of IPF to other idiopathic interstitial pneumonias (IIPs) is not known, despite the observation that different histopathologic patterns of IIP may coexist in the same patient. We propose that these different histopathologic 'reaction' patterns may be determined by complex interactions between host and environmental factors that alter the local alveolar milieu. Recent paradigms in IPF pathogenesis have focused on dysregulated epithelial-mesenchymal interactions, an imbalance in T(H)1/T(H)2 cytokine profile and potential roles for aberrant angiogenesis. In this review, we discuss these evolving concepts in disease pathogenesis and emerging therapies designed to target pro-fibrogenic pathways in IPF.

Reduced migration of fibroblasts in inflammatory bowel disease: role of inflammatory mediators and focal adhesion kinase

BACKGROUND & AIMS

Crohn's disease (CD) and ulcerative colitis (UC) are associated with chronic tissue damage and continuous tissue repair. A central, but not well-characterized, event during this process is the migration of activated fibroblasts to the wound.

METHODS

Human colonic lamina propria fibroblasts (CLPF) were isolated from patients with CD and UC and from healthy controls and were characterized by immunocytochemistry. Migration assays of CLPF were performed in the modified 48-well Boyden chamber. Focal adhesion kinase (FAK) and FAK autophosphorylation in migrating CLPF were determined by Western blotting. FAK mRNA expression was investigated by Northern blotting.

RESULTS

The migration of CD-CLPF and UC-CLPF was significantly reduced when compared with control-CLPF. This was correlated with a decrease in FAK phosphorylation, whereas, in migrating control-CLPF, an increase was found. Similarly, the presence of the inflammatory mediators interferon (IFN)-gamma (50 ng/mL) or tumor necrosis factor (TNF) (30 ng/mL) in conditioned medium significantly reduced the migration of control-CLPF to 41% +/- 4% or 30% +/- 7%, respectively. Preincubation of control-CLPF with TNF (20 ng/mL) and IFN-gamma (10 ng/mL) for 3 days reduced their migratory response to 10% of control (P < 0.001), which also was correlated with a decrease in FAK phosphorylation. Culture of IFN-gamma/TNF-treated CLPF for a further 7 days without cytokines did not restore the migratory potential and FAK phosphorylation, indicating a persistent functional change.

CONCLUSIONS

CD- and UC-CLPF have a reduced migratory potential compared with normal CLPF. That may be caused by contact with IFN-gamma and TNF. This loss of migratory potential was correlated with diminished FAK phosphorylation.

IFN-gamma fails to antagonize fibrotic effect of TGF-beta on keloid-derived dermal fibroblasts

BACKGROUND

Interferon-gamma (IFN-gamma) has been noted as a potential therapeutic agent for various fibrotic disorders, in part, through its antagonistic effect on a fibrogenic cytokine, transforming growth factor-beta (TGF-beta). Keloid is a fibrotic skin disorder that results in an excessive deposition of extracellular matrix, which is associated with altered-expression of or -responses to TGF-beta in dermal fibroblasts.

OBJECTIVE

We sought to determine whether IFN-gamma antagonized TGF-beta-mediated fibrotic response in keloid-derived dermal fibroblasts.

METHODS

Type I collagen production, fibroblast contractile activity, and alpha-smooth muscle actin (alpha-SMA) expression were assessed by using Western blotting, an in vitro type I collagen gel contraction assay, and immunofluorescence study in normal and keloid-derived human dermal fibroblasts in the presence or absence of IFN-gamma and/or TGF-beta.

RESULTS

In contrast to normal dermal fibroblasts, IFN-gamma did not inhibit TGF-beta-induced type I collagen production, contractile activity, and alpha-SMA expression in keloid-derived dermal fibroblasts. In addition, keloid-derived dermal fibroblasts constitutively expressed type I collagen and alpha-SMA with increased capacity to contract a collagen matrix.

CONCLUSION

IFN-gamma failed to antagonize TGF-beta-mediated fibrotic response in keloid-derived dermal fibroblasts. Thus, IFN-gamma may not be therapeutically useful for keloid and clarification of the molecular mechanisms underlying the IFN-gamma resistance should be investigated for therapeutic application of IFN-gamma for keloid.

Role of Th2 responses in the development of allergen-induced airway remodelling in a murine model of allergic asthma

(1) To clarify the involvement of Th2 responses in the development of allergen-induced airway remodelling, we investigated the effect of anti-CD4 monoclonal antibody (mAb) and anti-CD8 mAb, and the responses of IL-4 gene-knockout (KO) mice in a murine model of allergic asthma. (2) Mice were immunized twice by intraperitoneal injections of ovalbumin (OA), and exposed to aeroallergen (OA, 1% w v(-1)) for 3 weeks. Twenty-four hours after the final challenge, airway responsiveness to acetylcholine was measured, and bronchoalveolar lavage (BAL) and histological examinations were carried out. (3) Anti-CD4 mAb (1 mg kg(-1)) clearly inhibited allergen-induced increases in airway responsiveness to acetylcholine, the number of eosinophils in BAL fluid, serum OA-specific IgE levels, IL-13 and transforming growth factor-beta1 levels in BAL fluid, and amount of hydroxyproline in the lung by 100, 99, 100, 100, 84, and 60%, respectively. Furthermore, the antibody (1 mg kg(-1)) also attenuated allergen-induced goblet cell hyperplasia in the epithelium and subepithelial fibrosis by 72 and 83%, respectively. In contrast, anti-CD8 mAb (1 mg kg(-1)) showed no effect on each parameter. Furthermore, all these parameters were attenuated in IL-4KO mice by 57, 93, 100, 45, 84 and 60%, and also 72 and 83%, respectively. (4) These findings suggest that Th2 responses play a critical role for the development of allergen-induced airway remodelling, and that the inhibition of Th2 responses, e.g. using anti-CD4 mAb, is a therapeutic approach for the treatment of airway remodelling in asthma.

Extracorporeal photochemotherapy in the treatment of eosinophilic fasciitis

BACKGROUND

Eosinophilic fasciitis (EF) is a rare connective tissue disorder characterized clinically by symmetrical swelling, induration and thickening of the skin and histologically by thickening of the fascia with chronic inflammatory infiltrate containing eosinophils. The disease is classified in the spectrum morphea/systemic sclerosis and treated with systemic steroids and other immunosuppressant drugs.

OBJECTIVE

The purpose of this study was to use extracorporeal photochemotherapy (ECP) in patients with EF to evaluate the effectiveness of this therapy.

SUBJECTS AND METHODS

Three patients affected by EF were treated with ECP because they failed to respond or with contraindications to immunosuppressant treatment. The patients underwent ECP with a UVAR XTS apparatus. Subjects were treated on two consecutive days at 2-week intervals for the first 3 months and thereafter every 4 weeks on the basis of clinical response. The patients were assessed before therapy and then monthly by means of a clinical score. Changes in affected areas were evaluated at predetermined points by computerized skin elastometry (Cutometer SEM 474).

RESULT

After 1 year of therapy we found considerable improvement of clinical parameters in two cases. There was less striking improvement in the other case. These clinical results were confirmed by the elastometry measurements. All patients reported improved quality of life, which enabled a reduction in the dose of immunosuppressants.

CONCLUSION

ECP emerged as a safe and effective therapy in association with low doses of immunosuppressants in our three patients. A randomized comparative multicentre study between ECP as single therapy and ECP plus immunosuppressants and conventional therapies is required to firmly establish photopheresis as a possible basic treatment to combine with conventional therapies for EF.

Interleukin-4- and interleukin-13-enhanced transforming growth factor-beta2 production in cultured human bronchial epithelial cells is attenuated by interferon-gamma

Cytokines derived from lymphocytes are believed to play key roles in a variety of diseases, including airway diseases such as asthma. The current study was designed to evaluate the hypothesis that cytokines derived from Th2 cells, interleukin (IL)-4 and IL-13, might contribute to tissue remodeling by modulating the production of transforming growth factor (TGF)-beta. In addition, the ability of interferon (IFN)-gamma, a cytokine derived from Th1 cells that can antagonize many effects of IL-4 and IL-13, was also assessed for its effects on TGF-beta production. IL-4 and IL-13 both stimulated production of TGF-beta2 release from human bronchial epithelial cells in a time- and concentration-dependent manner. Both with and without acidification, TGF-beta2 were detected. Neither TGF-beta1 nor TGF-beta3 was released. In contrast to the stimulatory effect on human bronchial epithelial cells, neither IL-4 nor IL-13 stimulated release of any TGF-beta isoform from human lung fibroblasts. IFN-gamma reduced both basal, IL-4-, and IL-13-stimulated release of TGF-beta2 in human bronchial epithelial cells. The stimulatory effects of IL-4 and IL-13 and the inhibitory effect of IFN-gamma on TGF-beta2 release were paralleled by mRNA levels, as assessed by real-time reverse transcriptase-polymerase chain reaction (RT-PCR). In summary, the Th2-derived cytokines, IL-4 and IL-13, can stimulate production of TGF-beta from airway epithelial cells but not from lung fibroblasts. IFN-gamma, in contrast, can inhibit TGF-beta2 release both under basal conditions and following IL-4 or IL-13 stimulation. The ability of these cytokines to modulate TGF-beta release may contribute to both normal airway repair and to the development of subepithelial fibrosis in asthma.

Prostaglandin E(2) inhibits fibroblast chemotaxis

Fibroblasts are the major source of extracellular connective tissue matrix, and the recruitment, accumulation, and stimulation of these cells are thought to play important roles in both normal healing and the development of fibrosis. Prostaglandin E(2) (PGE(2)) can inhibit this process by blocking fibroblast proliferation and collagen production. The aim of this study was to investigate the inhibitory effect of PGE(2) on human plasma fibronectin (hFN)- and bovine bronchial epithelial cell-conditioned medium (BBEC-CM)-induced chemotaxis of human fetal lung fibroblasts (HFL1). Using the Boyden blind well chamber technique, PGE(2) (10(-7) M) inhibited chemotaxis to hFN 40.8 +/- 5.3% (P < 0.05) and to BBEC-CM 49.7 +/- 11.7% (P < 0.05). Checkerboard analysis demonstrated inhibition of both chemotaxis and chemokinesis. The effect of PGE(2) was concentration dependent, and the inhibitory effect diminished with time. Other agents that increased fibroblast cAMP levels, including isoproterenol (10(-5) M), dibutyryl cAMP (10(-5) M), and forskolin (3 x 10(-5) M) had similar effects and inhibited chemotaxis 54.1, 95.3, and 87.0%, respectively. The inhibitory effect of PGE(2) on HFL1 cell chemotaxis was inhibited by the cAMP-dependent protein kinase (PKA) inhibitor KT-5720, which suggests a cAMP-dependent effect mediated by PKA. In summary, PGE(2) appears to inhibit fibroblast chemotaxis, perhaps by modulating the rate of fibroblast migration. Such an effect may contribute to regulation of the wound healing response after injury.

Interferon-gamma 1b: impact of new indications (idiopathic pulmonary fibrosis)

Idiopathic pulmonary fibrosis (IPF) is a relentlessly progressive disease with inadequate response to conventional treatment with corticosteroids and/or immunosuppressive agents in most patients. Interferon-gamma (IFN-gamma), an antifibrotic agent, has been proposed as a novel therapeutic approach. Several investigators have shown a relative decrease in systemic and pulmonary IFN-gamma activity in patients with IPF. Experimental evidence from animal and human studies also suggests that IFN-gamma administration may ameliorate lung fibrosis. Clinical experience is, however, limited to a single clinical trial that showed objective functional improvement in a small number of patients treated with IFN-gamma and low-dose corticosteroids. Further research is needed to characterise the efficacy, safety and optimum route of administration of this agent before it can be recommended for use in routine clinical practice.

Wound healing after photorefractive keratectomy

For more than 15 years, the excimer laser has been used as a surgical instrument on the cornea. Photorefractive keratectomy (PRK) followed radial keratotomy as researchers sought a more precise technique. In PRK, precision turned out to depend on surgical technique as well as the wound-healing process, with the 2 factors interdependent. The PRK technique has evolved toward a large diameter, flat ablation curvatures, and an even surface. The role of such factors as cytokines and interleukins has become more clear in the past 10 years. However, understanding the wound-healing process becomes more complicated with increasing know edge. Learning the contributing factors and performing trials with new drugs and antibodies to modulate wound healing have shown positive results on the experimental level. Patient selection based on the concentration of epidermal growth factor in tears may be another way to increase PRK s precision. The PRK technique has taught much about wound healing. For the technique to be competitive, increased precision, particularly in eyes with high myopia, is needed. Two other factors are imperative: controlling postoperative pain and decreasing visual rehabilitation time.

Fibroblast biology. Signals targeting the synovial fibroblast in arthritis

Fibroblast-like cells in the synovial lining (type B lining cells), stroma and pannus tissue are targeted by many signals, such as the following: ligands binding to cell surface receptors; lipid soluble, small molecular weight mediators (eg nitric oxide [NO], prostaglandins, carbon monoxide); extracellular matrix (ECM)-cell interactions; and direct cell-cell contacts, including gap junctional intercellular communication. Joints are subjected to cyclic mechanical loading and shear forces. Adherence and mechanical forces affect fibroblasts via the ECM (including the hyaluronan fluid phase matrix) and the pericellular matrix (eg extracellular matrix metalloproteinase inducer [EMMPRIN]) matrices, thus modulating fibroblast migration, adherence, proliferation, programmed cell death (including anoikis), synthesis or degradation of ECM, and production of various cytokines and other mediators [1]. Aggressive, transformed or transfected mesenchymal cells containing proto-oncogenes can act in the absence of lymphocytes, but whether these cells represent regressed fibroblasts, chondrocytes or bone marrow stem cells is unclear.

Negative modulation of alpha1(I) procollagen gene expression in human skin fibroblasts: transcriptional inhibition by interferon-gamma

Interferon-gamma (IFN-gamma), a multifunctional cytokine produced by activated Th1 lymphocytes, exerts potent effects on the extracellular matrix by regulating fibroblast function. In this study, we examined the modulation of alpha1(I) procollagen gene (COL1A1) expression by recombinant IFN-gamma. The results showed that IFN-gamma stimulated the rapid accumulation of interferon regulated factor (IRF)-1 mRNA, followed by a delayed and dose-dependent inhibition of alpha1(I) procollagen mRNA expression in skin fibroblasts from several different donors. The inhibitory response was abrogated in fibroblasts stably expressing IRF-1 in the antisense orientation. A marked decrease in the amount of heterogeneous nuclear pre-mRNA preceded the inhibition of COL1A1 mRNA expression. In fibroblasts transiently transfected with COL1A1 promoter-chloramphenicol acetyltransferase reporter gene plasmids, IFN-gamma selectively inhibited promoter activity and abrogated its stimulation induced by TGF-beta. The inhibition by IFN-gamma was not due to downregulation of TGF-beta receptor mRNA expression in the fibroblasts or decreased ligand binding to the receptor. IFN-alpha and IFN-beta by themselves had little effect on promoter activity, but IFN-alpha augmented the inhibitory effect of IFN-gamma. Using a series of 5' deletion constructs, a proximal region of the COL1A1 promoter was shown to function as an IFN-gamma response element. This region of the gene harbors overlapping binding sites for transcription factors Sp1, Sp3, and NF-1 but no homologs of previously characterized IFN-gamma response elements. The putative IFN-gamma response region was sufficient to confer inhibition of reporter gene expression by treatment with IFN-gamma. Gel mobility shift analysis showed that two distinct and specific DNA-protein complexes were formed when fibroblast nuclear extracts were incubated with oligonucleotides spanning the IFN-gamma response region. IFN-gamma did not modify the ability of nuclear proteins to bind to this region. The results indicate that IFN-gamma inhibits COL1A1 expression in fibroblasts principally at the level of gene transcription. Inhibition involves IRF-1 and is mediated through a short proximal promoter segment but without an apparent change in promoter occupancy. The findings provide novel insight into the mechanism of IFN-gamma regulation of fibroblast function.

A randomized phase II trial of interferon-alpha2b versus 5-fluorouracil after trabeculectomy

PURPOSE

The aim of the present study was to investigate the safety and potential efficacy of subconjunctival interferon-alpha2b (IFN-alpha), either alone or in combination with 5-fluorouracil (5-FU), in reducing the risk of failure of glaucoma surgery

METHODS

A prospective, masked randomized phase II study was undertaken in which patients received three subconjunctival injections per week for 3-4 weeks postoperatively. Three treatments were compared: (i) IFN-alpha (1 x 10(6)IU per dose); (ii) 5-FU (5 mg per dose); and (iii) alternating IFN-alpha and 5-FU (BOTH). The primary outcome measures were: (i) rate of successful control of intra-ocular pressure without further surgery; and (ii) the incidence of side effects.

RESULTS

Fifty-seven patients undergoing glaucoma surgery with an increased risk of failure were evaluated, including 23 patients (40%) undergoing trabeculectomy combined with extracapsular cataract extraction as well as other conventional high-risk groups. With 53 patients (93%) completing 2 years follow up,there was no significant difference in success rates among the three groups. Intra-ocular pressure was controlled without further surgery in 79% of patients (95% confidence interval (CI): 61, 97%) receiving IFN-alpha, in 89% of patients (76, 100%) receiving 5-FU and in 89% of patients (76, 100% receiving BOTH. Side effects were similar among the three groups.

CONCLUSIONS

These results are consistent with a beneficial effect of IFN-alpha2b given either alone or in combination with 5-FU after glaucoma filtering surgery. However, the lack of a clear and substantial benefit over conventional anti-fibrotic therapy does not support the further clinical evaluation of these treatments.

Topical interferon alpha 2b for corneal haze after excimer laser photorefractive keratectomy. The Melbourne Excimer Laser Group

PURPOSE

To determine whether topical interferon alpha 2b (IFN-alpha) prevents corneal haze after excimer laser photorefractive keratectomy (PRK).

SETTING

Tertiary referral ophthalmic hospital.

METHOD

A prospective, double-blind, placebo-controlled, randomized study of 31 patients was undertaken. After surgery in a single institution, patients received a drop of either a placebo or IFN-alpha (5 x 10(6) IU/ml) four times daily for 4 weeks. The main outcome measures were corneal haze, refraction, and visual acuity.

RESULTS

The major side effect of interferon alpha treatment was a significant delay in epithelial healing by a mean of 2 days. The means of the average post-treatment clinical scores for haze in all patients up to 12 months after surgery were 0.46 +/- 0.25 for the IFN-alpha group and 0.64 +/- 0.43 for the placebo group (P = .20). Of patients with a correction of greater than 5.00 diopters (D), the IFN-alpha group had significantly less haze over the course of the study (0.39 +/- 0.23 versus 0.98 +/- 0.50; P = .03). After 12 months, the mean absolute spherical equivalent in the two groups was not significantly different (1.02 +/- 1.13 D versus 1.44 +/- 2.64 D). There was a tendency toward better uncorrected visual acuity in the INF-alpha group (P < .10, Kolmogorov-Smirnov).

CONCLUSION

Topical IFN-alpha may merit further investigation as a treatment to reduce corneal haze after excimer laser PRK for corrections greater than 5.00 D.

Interferon-beta, an autocrine cytokine, suppresses human fetal skin fibroblast migration into a denuded area in a cell monolayer but is not involved in the age-related decline of cell migration

The migration of human skin fibroblasts into a denuded area in a cell monolayer declined during in vitro and in vivo aging. We carried out a study to determine whether this age-related decline in cell migration was mediated by the autocrine cytokine interferon-beta (IFN-beta), which has been reported to suppress the proliferation, chemotaxis and collagen synthesis of human fibroblasts. Actually, IFN-beta specifically suppressed the migration of TIG-3S human fetal skin fibroblasts into a denuded area in a cell monolayer, as shown by the dose response experiments of IFN-beta and neutralizing anti-IFN-beta antibody. IFN-beta also inhibited their collagen synthesis but the addition of type I collagen could not reverse IFN-beta-induced inhibition of cell migration. Double strand RNA, which has been generally known to induce IFN-beta in human skin fibroblasts, suppressed the migration of TIG-3S cells. Next, a study was done to determine whether IFN-beta and double strand RNA suppressed the migration of TIG-3S cells in late passages as well as early passages, or whether neutralizing anti-IFN-beta antibody stimulated the migration of TIG-3S cells in late and middle passages. IFN-beta and double strand RNA suppressed the migration of TIG-3S cells in middle (PD45) and late (PD55) passages as well as in early passages (PD23-28). Neutralizing anti-IFN-beta antibodies could not reverse the low migratory activity of middle and late passage cells to the high migratory activity of early passage cells. These results indicated that the autocrine cytokine IFN-beta did not seem to be involved in the age-dependent decline of fibroblast migration.

Treatment of severe localized scleroderma by plasmapheresis--report of three cases

We report three patients with severe, localized scleroderma, and with elevated titres of antinuclear antibodies, who were treated by plasmapheresis in combination with systemic steroid therapy. The therapeutic effectiveness of plasmapheresis was assessed on the basis of improvement in cutaneous and joint lesions. In all cases, significant improvement occurred after 2 months of therapy. Thus, in addition to treating systemic sclerosis, plasmapheresis can also be recommended for treatment of severe cases of localized scleroderma with elevated titres of antinuclear antibodies and antibodies to ss-DNA.

Effects of aging and dietary restriction on activity of monkey serum in promoting fibroblast migration

In order to determine whether serum modified cellular aging in vivo, we previously studied the effects of serum from various mammals of different ages on cell functions such as proliferation and migration, and reported that cell migration was more greatly inhibited by serum from old donors than cell proliferation [1]. Moreover, since dietary restriction has been reported to extend lifespan and slow the aging rate of some animals [2], we wondered whether sera from dietary restricted and control monkeys of various ages might exhibit reduced aging effects on cell migration. When serum from young adult (3-5 years old) monkeys was added to plain medium, the migration of human fetal skin fibroblasts was very strongly inhibited compared to FBS. Surprisingly, sera from adult (6-11 years old) and old (more than 18 years old) monkeys caused significantly less migration-inhibitory activity than serum from young adult monkeys although sera from adult and old monkeys were much more inhibitory to cell migration than FBS. Dietary restriction only caused marginal effects on serum migration-promoting activity in a few monkey groups. The inhibition of cell migration caused by monkey serum was not brought about by cytotoxic effects since monkey serum stimulated cell proliferation as well as fetal bovine serum. These results indicate that the effects of aging on monkey serum migration-promoting activity are much more pronounced than those of dietary restriction.

Biphasic effects of interleukin-1 alpha on dermal fibroblasts: enhancement of chemotactic responsiveness at low concentrations and of mRNA expression for collagenase at high concentrations

Fibrotic reactions in the skin are frequently preceded by infiltration of inflammatory cells and subsequent migration of fibroblastic cells. Interleukin-1 is secreted by inflammatory cells and can regulate proliferation and protein synthesis of fibroblasts. Its role in fibroblast chemotaxis has not been elucidated in any detail. Using the well-established Boyden chamber assay for measurement of chemotaxis in vitro, we studied a wide range of recombinant human interleukin-1 alpha concentrations to assess intrinsic chemotactic activity of interleukin-1 alpha and to determine the capacity of this mediator to modify the chemotactic response of fibroblasts to other chemoattractants. This was compared with the interleukin-1 alpha dose required for enhancement of mRNA expression for collagenase. Although interleukin-1 alpha was not chemoattractive for fibroblasts, it specifically augmented migration toward fibroblast-conditioned medium and toward platelet-derived growth factor but not toward epidermal growth factor, fibronectin, or transforming-growth factor-beta. Interleukin-1 alpha did not measurably alter the expression of mRNA for the platelet-derived growth factor receptor or its platelet-derived growth factor-binding characteristics. Doses required to enhance fibroblast chemotaxis were distinctly lower than those required for stimulation of collagenase mRNA expression.

Simultaneous assessment of migration and proliferation of murine fibrosarcoma cells, as affected by hydroxyurea, vinblastine, cytochalasin B, Razoxane and interferon

Using porous cell culture chambers, we have simultaneously assessed growth and locomotion of cancer cells to investigate whether certain agents affect cell motility in addition to cell division. First, cells from a murine fibrosarcoma cell line, 1.0/L1, were grown in ordinary flask cultures to determine appropriate cell inocula. Doses of agents were selected to reduce the final 4 day culture cellularity to about 50%, when present during the last two days of culturing. Secondly, the effects of these agents on cell numbers in the porous chambers and on cell migration out of the chambers ('emigration fraction') were recorded. We also examined, using a similar type of porous chamber, whether the agents could affect leucocyte chemotaxis. Hydroxyurea (an inhibitor of DNA synthesis) reduced cancer cell emigration as well as cell growth, without interfering with leucocyte chemotaxis. Cytochalasin B (a microfilament disrupting agent) inhibited cancer cell motility and growth, as well as leucocyte chemotaxis. Vinblastine (a microtubule disrupting agent), at the very low dose chosen, reduced cancer cell growth, but did not consistently affect the migration of either cell type. The experimental anti-metastasis agent Razoxane reduced growth, but had no detectable effects on motility. High doses of natural murine interferon-alpha/beta weakly inhibited both cancer cell growth and locomotion. This motivates for further studies of these and other cytokines, as treatment with agents inhibiting cancer cell locomotion might possibly prevent peri-operative spread of cancer in patients.

Interferon-alpha 2b inhibits proliferation of human Tenon's capsule fibroblasts

To evaluate the potential of interferon-alpha 2b (IFN-alpha) as an antifibrotic treatment after glaucoma filtering surgery, we studied its ability to inhibit mitogen-induced proliferation of human Tenon's capsule fibroblasts in vitro, as shown by [3H]-thymidine incorporation. IFN-alpha inhibited fetal calf serum-induced proliferation in a dose-dependent manner in concentrations ranging from 10 to 10,000 IU/ml (P < 0.001). Inhibition was also found when IFN-alpha was added prior to the mitogen (P = 0.001); this inhibitory effect lasted at least 3 days. We suggest that IFN-alpha deserves further evaluation as a possible agent for the control of ocular fibrosis.

Control of fibrosis in systemic scleroderma

Scleroderma is characterized by an excessive deposition of collagen in all involved organs. This is due to an overproduction of extracellular matrix (ECM) molecules following induction of gene expression, whereas there is no evidence that the composition of the connective tissue matrix is altered. Several in vivo studies and in vitro experiments suggest that a close interaction between inflammatory cells and fibroblasts is required for the initial activation of fibroblasts. TGF-beta presumably plays an important role, but other cytokines, e.g., PDGF or FGF, may also be involved. Many of the ECM molecules have been shown to interact closely with fibroblasts and provide signals that regulate fibroblast metabolism. The cellular response towards those signals is a further aspect of fibrosis that has attracted attention during recent years. The altered expression of receptor proteins on the cell surface of scleroderma fibroblasts for example might explain in part the lack of down-regulation of collagen synthesis in late phases of the disease. This review summarizes the alterations of connective tissue in scleroderma, and discusses the role of cytokines as well as the ECM for the regulation of fibroblast function and their implication for the development of fibrosis.

Treatment of systemic sclerosis with gamma-interferon

Numerous drugs have been recommended for the treatment of systemic sclerosis, but without any significant effect on the fibrotic stage of this disorder. Because recombinant gamma-interferon (gamma-IFN) is a potent and selective inhibitor of fibroblast proliferation and collagen production by human dermal fibroblasts in vitro, we assessed the effects of gamma-IFN treatment on the skin and on pulmonary function in patients with systemic sclerosis. Fourteen patients entered the study, and nine completed the 12-month trial. Fifty micrograms/day of gamma-IFN was administered subcutaneously 3 days per week. At the end of the 12-month treatment period a significant improvement was observed in total skin score, and blood gas analysis showed a significant increase in Pa O2 during therapy with gamma-interferon. Other clinical parameters (dysphagia, Raynaud's phenomenon, cardiac involvement) were not altered significantly. No serious adverse effects were noted. These results suggest a beneficial effect of gamma-IFN on the cutaneous fibrotic abnormalities and on lung fibrosis in systemic sclerosis.

The effect of interferon-gamma on the invasiveness of HT-180 cells

It has been shown that tumour necrosis factor-alpha (TNF-alpha) induces the gene expression of collagenase and enhances the invasiveness of many cell types. However, we have previously demonstrated that interferon-gamma (IFN-gamma) induces the chemotactic response of cells and we have studied the in vitro effects of both cytokines on invasive migration using a human fibrosarcoma cell line (HT-1080). Invasive migration occurred with HT-1800 cells through a basement membrane equivalent (matrigel) and collagen type I gel. Pre-incubation of cells with increasing concentrations of IFN-gamma resulted in a dose-dependent reduction of this invasive migration. TNF-alpha considerably enhanced the invasiveness of HT-1080 cells and of fibroblasts. This effect could be significantly diminished by the pre-incubation of cells with IFN-gamma. Inhibition of invasiveness did not appear to be due to an altered binding to the barriers or altered collagenolytic activity of these cells, as shown by attachment and collagenase assays. These data support the concept that IFN-gamma can reduce the invasiveness of transformed cells which contributes to its in vivo anti-neoplastic effect.

Cytokines, fibrosis and the failure of glaucoma filtration surgery

Current therapies for the prevention of fibrosis after glaucoma filtering surgery can be effective but often produce unwanted side effects. An understanding of the cellular basis of the fibrotic reaction may lead to better treatments. Wound repair revolves around angiogenesis and the activation of fibroblasts by cytokines. These peptides, a number of which have been described, act together in intricately complicated networks to encourage fibroblast chemotaxis, proliferation and contractility, as well as to stimulate the production of glycosaminoglycans and collagen. Since interferons seem to inhibit many of these responses, they deserve further evaluation in the treatment of ocular fibrosis.

Tumor necrosis factor alpha induces invasiveness of human skin fibroblasts in vitro

The chemotactic response of fibroblasts plays an important role during wound healing and fibrosis. Several substances have been found to mediate fibroblast migration in vitro. In the tissue, however, fibroblasts have also the potential to pass through connective tissue barriers following a chemotactic stimulus. Since tumor necrosis factor alpha (TNF alpha) is a cytokine released by mononuclear cells during wound healing, we have been interested in studying its effect on the regulation of fibroblast chemotaxis and invasive migration. TNF alpha did not attract skin fibroblasts nor did it alter their chemotactic response towards other chemoattractants like fibroblast conditioned medium or fibronectin. However, whereas normal skin fibroblasts did not invade a collagen I gel, preincubation of the cells with TNF alpha markedly induced their invasive migration into the gel. This seems to be associated with a specific degradation of type I collagen, because TNF alpha did not promote the invasion of skin fibroblasts through a reconstituted basement membrane (Matrigel).

Interferon gamma inhibits both proliferation and expression of differentiation-specific alpha-smooth muscle actin in arterial smooth muscle cells

Differentiation of muscle cells is characterized morphologically by the acquisition of contractile filaments and characteristic shape changes, and on the molecular level by induction of the expression of several genes, including those for the muscle-specific alpha-actin isoforms. IFN-gamma is an inhibitor of proliferation for several cells, including vascular smooth muscle, and is also an inducer of differentiated properties for several hematopoietic cells. We have therefore investigated whether IFN-gamma affects the expression of alpha-smooth muscle actin in cultured arterial smooth muscle cells. Cells exposed to IFN-gamma show a reduction of alpha-smooth muscle actin-containing stress fibers, as detected by immunofluorescence. The effect was observed in all phases of the cell cycle, and was caused by a reduction of the synthesis of alpha-smooth muscle actin protein as revealed by two-dimensional electrophoretic analysis of actin isoforms. RNA hybridization using a cRNA probe that hybridizes to all actin mRNAs showed that IFN-gamma-treated cells have a reduced content of the 1.7-kb mRNA that codes for alpha-smooth muscle actin, and to a lesser extent, also of the 2.1-kb mRNA encoding the beta and gamma-cytoplasmic actins. The reduction of alpha-smooth muscle actin mRNA was confirmed using an alpha-smooth muscle actin-specific cRNA probe. The reduction of alpha-smooth muscle actin mRNA occurs within 12 h, and is dependent on protein synthesis, since cycloheximide treatment reversed the effect. The inhibition of this mRNA species was dose dependent, and detectable by RNA hybridization at a dose of 50 U/ml IFN-gamma. These results suggest that the differentiation of arterial smooth muscle cells is not necessarily coupled to an inhibition of cellular proliferation. Instead, IFN-gamma may regulate the expression of several genes that control both proliferation and expression of differentiation markers.

Down-regulation of alpha 3(VI) chain expression by gamma-interferon decreases synthesis and deposition of collagen type VI

Treatment of cultured human skin fibroblasts with increasing doses of gamma-interferon produces a distinct reduction of steady-state levels of the alpha 3 chain of collagen VI mRNA by about 60% but not of the alpha 1 and alpha 2 chain mRNAs. A similar decrease was also observed for collagen I and III mRNA while fibronectin mRNA remained at the same level. The decrease in alpha 3(VI) mRNA is accompanied by a reduced synthesis of collagen VI and by a reduced deposition of both collagen VI and fibronectin in urea-insoluble form in the cell matrix. No other gamma-interferon effects were observed for fibronectin biosynthesis. Immunoprecipitation of metabolically labeled collagen VI demonstrated a strongly reduced synthesis (by 65-80%) of intracellular alpha 3(VI) chains with no decrease found for alpha 1(VI) and alpha 2(VI) chains. All three chains were, however, found to be reduced in the culture medium. Pepsin treatment of immunoprecipitated collagen VI showed similar chain ratios for material in the culture medium obtained in the absence or presence of gamma-interferon. It indicates that correctly assembled heterotrimers of the composition [alpha 1(VI) alpha 2(VI) alpha 3(VI)] are formed and secreted also in the absence of an equivalent alpha 3(VI) chain synthesis but at a reduced rate. The data support previous predictions from sequence analyses [Chu et al. (1988) J. Biol. Chem. 263, 18,601-18,606] that collagen VI molecules composed of all three constituent chains are more stable than other assembly alternatives.

Bronchial epithelial cells produce lung fibroblast chemotactic factor: fibronectin

The interaction between the epithelial cells and the subjacent mesenchymal cells in the airway is thought to play a major role during tissue repair after airway injury and lung morphogenesis. To evaluate this interaction, we cultured human lung fibroblasts, and bovine and human bronchial epithelial cells, and determined that bronchial epithelial cell-conditioned medium has a chemotactic activity for lung fibroblasts. This activity had the characteristics of protein: it was nondialyzable, heat-labile, pepsin-labile, acid-stable, and lipid-inextractable. Molecular sieve chromatography on Sephadex G-150 and affinity chromatography on gelatin-Sepharose revealed that there was one peak of chemotactic activity in high molecular weight range, which bound to gelatin, thus suggesting that the chemotactic factor might be fibronectin. Production and secretion of fibronectin into the culture media were demonstrated by biosynthetic incorporation of radioactive amino acid into fibronectin followed by immunoprecipitation on SDS-PAGE and autoradiography. Release into the culture medium was confirmed by ELISA. The identity of fibronectin as the chemotactic activity was confirmed by the addition of antifibronectin antibody to the conditioned medium, which inhibited chemotaxis in dose-dependent manner. Thus, bronchial epithelial cells produce fibronectin which can function as a chemotactic factor for lung fibroblasts. This production of fibronectin by bronchial epithelial cells may play an important role in regulating interaction between the bronchial epithelial cells that line the lumenal surface of the bronchial epithelial wall and the mesenchymal fibroblasts that underlie the bronchial epithelial basement membrane.

Enhanced metastases of a mouse carcinoma after in vitro treatment with murine interferon gamma

We have studied the influence of interferons (IFNs) on the metastatic potential of mouse colon adenocarcinoma, COLON 26, cells. Pre-treatment of the cells in vitro for 24 hr with recombinant murine IFN-gamma (rMuIFN-gamma) significantly increased the number of lung tumour nodules when cells were injected i.v. into immunocompetent BALB/c mice and BALB/c nude mice. However, when MuIFN-gamma-pre-treated cells were injected into beige (NK-deficient) nude mice or anti-asialoGM 1 (asGM 1)-serum-treated BALB/c mice (NK-depleted) no enhancement of metastatic potential was seen. Pre-treatment of COLON 26 cells with recombinant human IFN-alpha A/D (Bg1 I), an IFN with equal activity on human and mouse cells, did not significantly enhance their subsequent metastases in immunocompetent or immunodeficient mice. In fact, there was a small but significant decrease in the number of tumour nodules in the lungs of beige nude and asGM 1-treated mice. The effects of rMuIFN-gamma on COLON 26 cells did not appear to be related to an alteration in MHC expression. COLON 26 cells constitutively express H-2D and H-2K antigens and both IFNs had equal enhancing (approx. 2-fold) activity on the expression of these antigens at the doses used in this experiment (10(3)U/ml). We conclude that pre-treatment with rMuIFN-gamma renders COLON 26 cells resistant to in vivo NK-cell lysis via a mechanism that does not involve changes in MHC expression.