Tumor necrosis factor inhibits collagen and fibronectin synthesis in human dermal fibroblasts

Two Distinct Mechanisms Underlying γδ T Cell-Mediated Regulation of Collagen Type I in Lung Fibroblasts

Idiopathic pulmonary fibrosis is a chronic intractable lung disease, leading to respiratory failure and death. Although anti-fibrotic agents delay disease progression, they are not considered curative treatments, and alternative modalities have attracted attention. We examined the effect of human γδ T cells on collagen type I in lung fibroblasts. Collagen type I was markedly reduced in a γδ T cell number-dependent manner following treatment with γδ T cells expanded with tetrakis-pivaloxymethyl 2-(thiazole-2-ylamino) ethylidene-1,1-bisphosphonate (PTA) and interleukin-2. Collagen type I levels remained unchanged on addition of γδ T cells to the culture system through a trans-well culture membrane, suggesting that cell–cell contact is essential for reducing its levels in lung fibroblasts. Re-stimulating γδ T cells with (E)-4-hydroxy-3-methylbut-2-enyl diphosphate (HMBPP) reduced collagen type I levels without cell–cell contact, indicating the existence of HMBPP-induced soluble anti-fibrotic factors in γδ T cells. Adding anti-interferon-γ (IFN-γ)-neutralizing mAb restored collagen type I levels, demonstrating that human γδ T cell-derived IFN-γ reduces collagen type I levels. Conversely, interleukin-18 augmented γδ T cell-induced suppression of collagen type I. Therefore, human γδ T cells reduce collagen levels in lung fibroblasts via two distinct mechanisms; adoptive γδ T cell transfer is potentially a new therapeutic candidate.

Tumor necrosis factor-α promotes and exacerbates calcification in heart valve myofibroblast populations

Pro-inflammatory cytokines play critical roles in regulating valvular interstitial cell (VIC) phenotypic changes that can cause heart valve fibrosis and calcification. Tumor necrosis factor alpha (TNF-α) is a cytokine known to influence VIC behavior and has been reported at high levels in calcified valves ex vivo. We sought to understand the specific effects of TNF-α on VIC phenotypes (eg, fibroblast, profibrotic activated myofibroblasts) and its link with heart valve disorders. We characterize human aortic valve tissue from patients with valve disorders and identify a high variability of fibrotic and calcific markers between tissues. These results motivated in vitro studies to explore the effects of TNF-α on defined VIC fibroblasts and profibrotic activated myofibroblasts, induced via FGF-2 and TGF-β1 treatment. Using 3D hydrogels to culture VICs, we measure the effect of TNF-α (0.1-10 ng/mL) on key markers of fibrosis (eg, αSMA, COL1A1) and calcification (eg, RUNX2, BMP2, and calcium deposits). We observe calcification in TNF-α-treated VIC activated myofibroblasts and identify the MAPK/ERK signaling cascade as a potential pathway for TNF-α mediated calcification. Conversely, VIC fibroblasts respond to TNF-α with decreased calcification. Treatment of VIC profibrotic activated myofibroblast populations with TNF-α leads to increased calcification. Our in vitro findings correlate with findings in diseased human valves and highlight the importance of understanding the effect of cytokines and signaling pathways on specific VIC phenotypes. Finally, we reveal MAPK/ERK as a potential pathway involved in VIC-mediated matrix calcification with TNF-α treatment, suggesting this pathway as a potential pharmaceutical target for aortic valve disease.

Twist1 in T Lymphocytes Augments Kidney Fibrosis after Ureteral Obstruction

Background

Twist1 is a basic helix-loop-helix domain-containing transcription factor that participates in diverse cellular functions, including epithelial-mesenchymal transition and the cellular immune response. Although Twist1 plays critical roles in the initiation and progression of kidney diseases, the effects of Twist1 in the T lymphocyte on the progression of renal fibrosis require elucidation.

Methods

129/SvEv mice with a floxed allele for the gene encoding Twist1 or TNFα were bred with CD4-Cre mice to yield CD4-Cre⁺ Twist1^flox/flox (Twist1-TKO) or CD4-Cre⁺ TNF^flox/flox (TNF-TKO) mice with robust, but selective, deletion of Twist1 or TNFα mRNA in T cells, respectively. Twist1 TKO, TNF TKO, and WT controls underwent UUO with assessment of kidney fibrosis and T-cell phenotype at 14 days.

Results

Compared with WT controls, obstructed kidneys from Twist1 TKO mice had attenuated extracellular matrix deposition. Despite this diminished fibrosis, Twist1 TKO obstructed kidneys contained more CD8⁺ T cells than in WTs. These intrarenal CD8⁺ T cells exhibited greater activation and higher levels of TNFα expression than those from WT obstructed kidneys. Further, we found that selective deletion of TNFα from T cells exaggerated renal scar formation and injury after UUO, highlighting the capacity of T-cell TNF to constrain fibrosis in the kidney.

Conclusions

Twist1 in T cells promotes kidney fibrogenesis, in part, by curtailing the renal accumulation of TNF-elaborating T cells.

Asiaticoside might attenuate bleomycin-induced pulmonary fibrosis by activating cAMP and Rap1 signalling pathway assisted by A2AR

Asiaticoside (AS) has been reported to have protective effect on pulmonary fibrosis (PF). In this study, we aimed to explore the potential mechanism of the therapeutic role of AS and its relationship with A2AR in PF. Adenosine 2A receptor gene knockout (A2AR^−/−) mice and wild‐type (WT) mice were used to establish bleomycin (BLM)‐induced PF models and were then treated with AS (50 mg/kg/d). Pulmonary inflammation and fibrosis were observed in the PF model with much higher severity in A2AR^−/−mice than that in WT mice and AS significantly alleviated lung inflammation and fibrosis; however, it was less effective in A2AR^−/− mice than in WT mice via histopathological analysis. Using RNA sequencing analysis, we found up‐regulated differentially expressed genes (DEGs) in BLM group were enriched in immune and inflammation‐associated pathways compared with control group. There were 242 common DEGs between down‐regulated in BLM vs control group and up‐regulated in BLM + AS vs BLM group, which were enriched in cAMP and Rap1 signalling pathways. Furthermore, the expression of five key factors of these two pathways including adenylate cyclase (ADCY1, ADCY5, ADCY8, cAMP and Rap1) were confirmed up‐regulated by AS with the presence of A2AR. Therefore, AS might attenuate BLM‐induced PF by activating cAMP and Rap1 signalling pathways which is assisted by A2AR, making it a promising therapeutic optional for PF.

Analysis of gene expression profiles and protein-protein interaction networks in multiple tissues of systemic sclerosis

Background

Systemic sclerosis (SSc), a multi-organ disorder, is characterized by vascular abnormalities, dysregulation of the immune system, and fibrosis. The mechanisms underlying tissue pathology in SSc have not been entirely understood. This study intended to investigate the common and tissue-specific pathways involved in different tissues of SSc patients.

Methods

An integrative gene expression analysis of ten independent microarray datasets of three tissues was conducted to identify differentially expressed genes (DEGs). DEGs were mapped to the search tool for retrieval of interacting genes (STRING) to acquire protein–protein interaction (PPI) networks. Then, functional clusters in PPI networks were determined. Enrichr, a gene list enrichment analysis tool, was utilized for the functional enrichment of clusters.

Results

A total of 12, 2, and 4 functional clusters from 619, 52, and 119 DEGs were determined in the lung, peripheral blood mononuclear cell (PBMC), and skin tissues, respectively. Analysis revealed that the tumor necrosis factor (TNF) signaling pathway was enriched significantly in the three investigated tissues as a common pathway. In addition, clusters associated with inflammation and immunity were common in the three investigated tissues. However, clusters related to the fibrosis process were common in lung and skin tissues.

Conclusions

Analysis indicated that there were common pathological clusters that contributed to the pathogenesis of SSc in different tissues. Moreover, it seems that the common pathways in distinct tissues stem from a diverse set of genes.

EDA fibronectin-TLR4 axis sustains megakaryocyte expansion and inflammation in bone marrow fibrosis

The fibronectin EDA isoform (EDA FN) is instrumental in fibrogenesis but, to date, its expression and function in bone marrow (BM) fibrosis have not been explored. We found that mice constitutively expressing the EDA domain (EIIIA+/+), but not EDA knockout mice, are more prone to develop BM fibrosis upon treatment with the thrombopoietin (TPO) mimetic romiplostim (TPOhigh). Mechanistically, EDA FN binds to TLR4 and sustains progenitor cell proliferation and megakaryopoiesis in a TPO-independent fashion, inducing LPS-like responses, such as NF-κB activation and release of profibrotic IL-6. Pharmacological inhibition of TLR4 or TLR4 deletion in TPOhigh mice abrogated Mk hyperplasia, BM fibrosis, IL-6 release, extramedullary hematopoiesis, and splenomegaly. Finally, developing a novel ELISA assay, we analyzed samples from patients affected by primary myelofibrosis (PMF), a well-known pathological situation caused by altered TPO signaling, and found that the EDA FN is increased in plasma and BM biopsies of PMF patients as compared with healthy controls, correlating with fibrotic phase.

Patient with ankylosing spondylitis and scleroderma renal crisis

We report a 56-year-old man with a history of ankylosing spondylitis and systemic scleroderma. The patient had been diagnosed with ankylosing spondylitis 20 years ago and had been receiving treatment with NSAIDs and anti TNFα drugs. He referred to our rheumatology department for Raynaud’s phenomenon, arthralgias and weight loss. Physical examination revealed stiffness of the skin with difficulty in pinching (mainly at lower extremities, from knee to ankle). Soon after his first visit to our department, he developed renal scleroderma crisis with abrupt increase in blood pressure, decline in renal function, and microangiopathic haemolytic anaemia in accordance with positive antinuclear autoantibodies and positive anti-topoisomerase I antibody (anti-Scl70). This is one of the few reports in the literature of coexistence of ankylosing spondylitis and systemic scleroderma. A genetic correlation seems to be an explanation in some patients who carry one or two susceptibility alleles to both diseases. Thus, this might be the case of a ‘genetic trap’ in which distinct genes are cooperating to favour the susceptibility to two different HLA-associated systemic autoimmune diseases.

Protective Effect of Infliximab, a Tumor Necrosis Factor-Alfa Inhibitor, on Bleomycin-Induced Lung Fibrosis in Rats

We aimed to investigate the preventive effect of Infliximab (IFX), a tumor necrosis factor (TNF)-α inhibitor, on bleomycin (BLC)-induced lung fibrosis in rats. Rats were assigned into four groups as follows: I-BLC group, a single intra-tracheal BLC (2.5 mg/kg) was installed; II-control group, a single intra-tracheal saline was installed; III-IFX + BLC group, a single-dose IFX (7 mg/kg) was administered intraperitoneally (i.p.), 72 h before the intra-tracheal BLC installation; IV-IFX group, IFX (7 mg/kg) was administered alone i.p. on the same day with IFX + BLC group. All animals were sacrificed on the 14th day of BLC installation. Levels of tumor necrosis factor (TNF)-α, transforming growth factor (TGF)-β, interleukin (IL)-6, periostin, YKL-40, nitric oxide (NO) in rat serum were measured, as well as, myeloperoxidase (MPO), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) activity, and reduced glutathione (GSH), hydroxyproline, malondialdehyde (MDA) content in lung homogenates. Lung tissues were stained with hematoxylin and eosin (H&E) for quantitative histological evaluation. The inducible nitric oxide synthase (iNOS) expression and cell apoptosis in the lung tissues were determined quantitatively by immunohistochemical staining (INOS) and by TUNNEL staining, respectively. BLC installation worsened antioxidant status (such as SOD, CAT, GPx, GSH, MPO), while it increased the serum TNF-α, TGF-β, IL-6, periostin, YKL-40, and lipid peroxidation, and collagen deposition, measured by MDA and hydroxyproline, respectively. IFX pretreatment improved antioxidant status as well as BLC-induced lung pathological changes, while it decreased the TNF-α, TGF-β, IL-6, periostin, YKL-40, lipid peroxidation and collagen deposition. Finally, histological, immunohistochemical, and TUNNEL evidence also supported the ability of IFX to prevent BLC-induced lung fibrosis. The results of the present study indicate that IFX pretreatment can attenuate BLC-induced pulmonary fibrosis.

Is immunosuppressive therapy the anchor treatment to achieve remission in systemic sclerosis?

Since activation of the immune system and a perivascular infiltrate of inflammatory cells are key features of SSc, immunosuppression has long been considered to be an anchor treatment. Non-selective immunosuppression remains central to the treatment of interstitial lung disease (ILD) and skin involvement, with CYC most widely used to obtain remission. The use of MTX as a first-line agent may be considered in the presence of skin involvement without ILD. More recently, MMF has shown encouraging results in observational studies, but still needs more formal evaluation to verify if it can be considered an alternative drug to CYC or a maintenance agent such as AZA. Rituximab has provided promising results in small open-label studies and other novel therapies targeting specific molecular and cellular targets are under evaluation. Patients with rapidly progressing diffuse cutaneous SSc should be evaluated for haematopoietic stem cell transplantation.

Esophageal epithelial cells acquire functional characteristics of activated myofibroblasts after undergoing an epithelial to mesenchymal transition

BACKGROUND AND AIMS

Eosinophilic esophagitis (EoE) is an allergic inflammatory disease that leads to esophageal fibrosis and stricture. We have recently shown that in EoE, esophageal epithelial cells undergo an epithelial to mesenchymal transition (EMT), characterized by gain of mesenchymal markers and loss of epithelial gene expression. Whether epithelial cells exposed to profibrotic cytokines can also acquire the functional characteristics of activated myofibroblasts, including migration, contraction, and extracellular matrix deposition, is relevant to our understanding and treatment of EoE-associated fibrogenesis. In the current study, we characterize cell migration, contraction, and collagen production by esophageal epithelial cells that have undergone cytokine-induced EMT in vitro.

METHODS AND RESULTS

Stimulation of human non-transformed immortalized esophageal epithelial cells (EPC2-hTERT) with profibrotic cytokines TNFα, TGFβ, and IL1β for three weeks led to acquisition of mesenchymal αSMA and vimentin, and loss of epithelial E-cadherin expression. Upon removal of the profibrotic stimulus, epithelial characteristics were partially rescued. TGFβ stimulation had a robust effect upon epithelial collagen production. Surprisingly, TNFα stimulation had the most potent effect upon cell migration and contraction, exceeding the effects of the prototypical profibrotic cytokine TGFβ. IL1β stimulation alone had minimal effect upon esophageal epithelial migration, contraction, and collagen production.

CONCLUSIONS

Esophageal epithelial cells that have undergone EMT acquire functional characteristics of activated myofibroblasts in vitro. Profibrotic cytokines exert differential effects upon esophageal epithelial cells, underscoring complexities of fibrogenesis in EoE, and implicating esophageal epithelial cells as effector cells in EoE-associated fibrogenesis.

Caffeic acid phenethyl ester prevents detrimental effects of remote ischemia-reperfusion injury on healing of colonic anastomoses

PURPOSE

We aimed to investigate whether caffeic acid phenethyl ester (CAPE) prevents detrimental systemic effects of intestinal ischemia-reperfusion (IR) injury on colonic anastomotic wound healing.

METHODS

This experimental study was conducted on 48 male Wistar albino rats. The rats were randomly allocated into four groups and a left colonic anastomosis was performed in all rats: (i) sham-operated group (n = 12), laparatomy without intestinal IR injury; (ii) sham + CAPE group (n = 12), identical to Group 1 except for CAPE treatment (10 μmol/kg, intravenously); (iii) intestinal IR group (n = 12), 60 min of superior mesenteric ischemia followed by reperfusion; and (iv) IR + CAPE-treated group (n = 12) (10 μmol/kg, intravenously, 30 min before the construction of colonic anastomosis). On the postoperative day 7, the rats were subjected to relaparotomy for in vivo measurement of the colonic anastomotic bursting pressure. A colonic segment including the anastomotic site was resected for histopathological evaluation and biochemical analyses. The plasma proinflammatory cytokine levels were measured. Body weight changes were examined.

RESULTS

CAPE treatment significantly increased colonic anastomotic bursting pressures, and colonic anastomotic tissue hydroxyproline contents and antioxidant parameters (p < .05), and significantly decreased oxidative stress markers in colonic anastomotic tissues and plasma proinflammatory cytokine levels (p < .05). Histopathological scores were significantly better due to CAPE administration (p < .05).

CONCLUSIONS

This study clearly showed that CAPE treatment prevented the delaying effects of remote IR injury on colonic anastomotic wound healing. Further clinical studies are required to determine whether CAPE has a useful role in the enhancement of gastrointestinal anastomotic wound healing during particular surgeries in which IR-induced organ injury occurs.

Differential expression of matrix metalloproteases in human fibroblasts with different origins

Fibroblasts are widely distributed cells and are responsible for the deposition of extracellular matrix (ECM) components but also secrete ECM-degrading matrix metalloproteases. A finely balanced equilibrium between deposition and degradation of ECM is essential for structural integrity of tissues. In the past, fibroblasts have typically been understood as a uniform cell population with comparable functions regardless of their origin. Here, we determined growth curves of fibroblasts derived from heart, skin, and lung and clearly show the lowest proliferation rate for cardiac fibroblasts. Furthermore, we examined basal expression levels of collagen and different MMPs in these three types of fibroblasts and compared these concerning their site of origin. Interestingly, we found major differences in basal mRNA expression especially for MMP1 and MMP3. Moreover, we treated fibroblasts with TNF-α and observed different alterations under these proinflammatory conditions. In conclusion, fibroblasts show different properties in proliferation and MMP expression regarding their originated tissue.

Biological treatments and connective tissue disease associated interstitial lung disease

PURPOSE OF REVIEW

There is no specific therapy for interstitial lung disease associated with connective tissue diseases (CTDs-ILD), a potentially fatal condition for some of these patients. This article reviews currently available information on the effects on CTDs-ILD of biological treatments that are increasingly used with considerable success in various systemic diseases.

RECENT FINDINGS

A beneficial effect of antitumor necrosis factor (TNF) agents on CTDs-ILD has been described in sporadic patients with rheumatoid arthritis (RA), systemic sclerosis (SSc) and systemic lupus erythematosus (SLE). However, and despite the fact that there was no clear evidence of pulmonary toxicity of these agents in randomized-controlled trials comprising thousands of patients with RA and spondylarthropathies, new onset or exacerbation of preexisting ILD with high mortality rates has so far been observed in 144 RA patients following anti-TNF treatment in clinical practice. Likewise, administration of the B-cell depleting anti-CD20 antibody rituximab was beneficial for ILD in SSc patients but associated with new-onset ILD in isolated patients with RA and SLE. Pertinent information on other biological treatments is currently lacking.

SUMMARY

Data on the therapeutic role of biological agents in CTDs-ILD is preliminary and controversial. Although preexisting ILD is not a contraindication for these agents, until more information is available their administration should be stopped when new pulmonary symptoms occur.

Expression of TNF-α and RANTES in drug-induced human gingival overgrowth

Objectives:

Regulated on activation, normal T cell expressed and secreted (RANTES) is a chemokine that is produced by fibroblasts, lymphoid and epithelial cells of the mucosa in response to various external stimuli. RANTES expression has been demonstrated in a variety of diseases characterized by inflammation, including asthma, transplantationassociated accelerated atherosclerosis, endometriosis and fibrosis. RANTES mRNA is quickly up-regulated by tumor necrosis factor (TNF)-α stimulation. Cyclosporine A (CsA) is widely used in organ transplant patients, often causing various side-effects including gingival overgrowth, which is fibrotic in nature. This study was carried out to assess the mRNA expression of TNF-α and RANTES in healthy individual, chronic periodontitis and CsAinduced gingival overgrowth tissues.

Materials and Methods:

Gingival tissue samples were collected from chronic periodontitis, CsAinduced gingival overgrowth patients and healthy individuals. Total RNA was isolated and reverse transcription polymerase chain reaction (RT-PCR) was performed for TNF-α and RANTES expression.

Results:

The results suggest that CsAinduced gingival overgrowth tissues expressed significantly increased TNF-α and RANTES compared to control and chronic periodontitis.

Conclusion:

The findings of the present study suggest that CsA can modify the expression of TNF-α and RANTES in drug-induced human gingival overgrowth.

Particulate β-glucan induces TNF-α production in wound macrophages via a redox-sensitive NF-κβ-dependent pathway

Glucans are known to promote wound repair. Noncellulosic β-glucans are recognized as potent immunological activators. β-Glucans are generally safe and are known to attenuate the rate of postoperative infection. Glyc101 is a particulate β-glucan isolated from Saccharomyces cerevisiae. In this study, the hypothesis that Glyc101 regulates wound macrophage function was tested. Glyc101 induced tumor necrosis factor (TNF) α transcription in macrophages isolated from murine wound site. Multiplex assay identified interleukin (IL)-10 and TNFα as two cytokines that are induced by Glyc101 in human blood monocyte-derived macrophages. Glyc101-induced TNFα production was observed to be mediated via the TLR-2 and dectin-1 receptors, receptor tyrosine kinases and NFκB activation. In murine wound macrophages, Glyc101 potentiated phorbol 12-myristate 13-acetate-induced respiratory burst. In vivo, implantation of Glyc101-enriched polyvinyl alcohol-sponges at the wound-site induced TNFα expression in macrophages. Consistently, Glyc101 induced TNFα expression in wound-site macrophages isolated from two patients with chronic wounds. These observations establish the translational significance of the net findings of this study. Activation of wound macrophages by Glyc101 represents one of the potential mechanisms by which this β-glucan may benefit chronic wounds where inefficient inflammatory response is one of the underlying causes of impaired healing.

Immunotherapy of systemic sclerosis

Scleroderma is a multisystem autoimmune disease characterized by an abnormal immune activation associated with the development of underlying vascular and fibrotic disease manifestations. This article highlights the current use of drugs targeting the immune system in scleroderma. Nonselective immunosuppression, and in particular cyclophosphamide, remains the main treatment for progressing skin involvement and active interstitial lung disease. Mycophenolate mofetil is a promising alternative to cyclophosphamide. The use of cyclosporine has been limited by modest efficacy and serious renal toxicity. Newer T-cell (sirolimus and alefacept) and B-cell (rituximab)-targeted therapies have provided some encouraging results in small pilot studies. Hematopoietic stem cell transplantation can be effective for severe fibrotic skin disease, but toxicity remains a concern. Clinical efficacy and safety of antifibrotic treatments (e.g., imatinib) await confirmation. Newer biological agents targeting key molecular or cellular effectors in scleroderma pathogenesis are now available for clinical testing.

Biologic therapy for systemic sclerosis: a systematic review

OBJECTIVE

Biologic agents are increasingly used in the rheumatic diseases. Their role in patients with systemic sclerosis (SSc) is uncertain. Our aim was to evaluate the effectiveness and safety of biologic agents in SSc. We review the evidence for the use of biologic agents to improve inflammatory arthritis, disability, and skin score, and we review adverse effects with biologic agents in patients with SSc.

METHODS

A systematic literature review was performed to identify studies evaluating the use of biologic agents in SSc. Medline, Embase, CINAHL, and Cochrane Database of Systematic Reviews were searched. A standardized abstraction form was used to extract biologic agent, study design, sample size, treatment effect, and adverse effects.

RESULTS

A total of 23 studies from 1413 citations were evaluated. Three studies evaluated infliximab, 3 evaluated etanercept, 3 evaluated antithymocyte globulin, 3 evaluated imatinib, 6 evaluated rituximab, and 1 study each evaluated interferon-γ (IFN-γ), IFN-α, relaxin, delipidated, deglycolipidated Mycobacterium vaccae, human anti-transforming growth factor ß1 antibody, and oral type I collagen. Studies of etanercept and infliximab suggest improvements in inflammatory arthritis and Health Assessment Questionnaire Disability Index (HAQ-DI). None of the other biologic agents demonstrated reproducible, statistically significant improvements in joint count, HAQ-DI, or skin score.

CONCLUSION

Anti-tumor necrosis factor-α agents may improve inflammatory arthritis and disability in SSc. The effect on skin score is uncertain. Adequately powered trials are needed to evaluate efficacy, and longitudinal studies are needed to evaluate longterm safety of these agents in SSc.

Reduction of adhesion formation and promotion of wound healing after laminectomy by pharmacological inhibition of pro-inflammatory cytokines: an experimental study in the rat

In a previous experiment using TNF inhibition in the rat it was accidentally found that adhesion and scar formation was reduced compared to previous experience. Wound and bone healing also seemed enhanced. The present study was conducted to assess if this observation could be verified in a controlled setting using a standardized laminectomy in the rat. Five rats received doxycycline and five other rats received saline and served as control. Macroscopic blinded evaluation 1 week after the laminectomy revealed that adhesion and scar formation was less in doxycycline-treated animals than in control animals. Wound and bone healing was found to be better in doxycycline-treated animals. The mechanisms for the observed effects cannot be fully understood but the data indicate that further research may lead to opportunities to design pharmacological modalities to reduce adhesion and scar formation, maybe in combination with suitable barriers.

In vivo effect of hyperbaric oxygen on wound angiogenesis and epithelialization

Hyperbaric oxygen (HBO) therapy is increasingly being used in different areas of medical practice. While demonstrated to be effective in several settings, its mechanism of action is not well understood. In the present study, we determined the effects of HBO on wound epithelialization and neovascularization in an in vivo hairless mouse ear "impaired" wound model. To impair wound healing, macrophages were depleted by pretreatment with iota-carrageenan. Wound epithelialization and neovascularization were measured using intravital microscopy and computerized planimetry. Metalloproteinase-2 (MMP-2), MMP-9, tissue inhibitor of metalloproteinase-1 (TIMP-1), and tumor necrosis factor-alpha (TNF-alpha) were measured on days 2 and 7 using immunohistochemistry. In nonimpaired healing wounds, the rate of epithelialization and neovascularization was significantly accelerated in the groups treated with HBO. Time to wound closure was significantly delayed in impaired compared with nonimpaired healing wounds and HBO treatment completely reversed this delay. Neither HBO treatment nor macrophage depletion caused significant alterations in MMP-2 expression in wounds. In contrast, TNF-alpha, MMP-9, and TIMP-1 were significantly up-regulated in the impaired healing group receiving HBO treatment. These results show that HBO therapy effectively reversed the negative effect exerted by macrophage reduction on wound epithelialization and neovascularization. This beneficial effect could be due to stimulation of TNF-alpha production and, to a lesser degree due to release of metalloproteinases.

Activated protein C prevents deleterious effects of remote reperfusion injury caused by intestinal ischemia on wound healing in the left colonic anastomoses: an experimental study in the murine model

BACKGROUND

Activated protein C (APC) is a serine protease with anticoagulant and antiinflammatory activities. The delaying effects of remote reperfusion injury on the wound-healing process in colonic anastomoses have been previously shown. In this study, we aimed to investigate whether APC protects against deleterious systemic effects of intestinal ischemia/reperfusion (I/R) injury on colonic anastomotic wound healing process.

METHODS

Male Wistar-albino rats were randomly allocated into 4 groups, and a left colonic anastomosis was performed in all animals: (1) sham-operated group, simultaneously with left colonic anastomosis, the superior mesenteric artery and collateral branches were divided from the celiac axis, and the inferior mesenteric artery were isolated but not occluded (group 1, n = 12), (2) sham + APC group, identical to group 1 except for APC treatment (100 microg/kg, intravenously, 15 minutes before construction of the colonic anastomosis), (group 2, n = 12), (3) intestinal I/R group, 60 minutes of superior mesenteric ischemia followed by reperfusion (group 3, n = 12), and (4) APC-treated group, (100 microg/kg, intravenously, 15 minutes before reperfusion) (group 4, n = 12). All animals were sacrificed, and colonic anastomotic bursting pressures were measured in vivo on day 7. Tissue samples were obtained for analysis of hydroxyproline contents, nitrate/nitrite levels, and activities of oxidative and antioxidative enzymes. The plasma levels of proinflammatory cytokines and D-dimer were also measured.

RESULTS

Intestinal I/R led to significant decreases in colonic anastomotic bursting pressures, tissue hydroxyproline contents, and activities of antioxidative enzymes, along with increases in tissue nitrate/nitrite levels, activities of oxidative enzymes, and plasma levels of proinflammatory cytokines and D-dimer (P < .05). However, APC treatment led to significant increases in colonic anastomotic bursting pressures, tissue hydroxyproline contents, and activities of antioxidative enzymes, along with decreases in tissue nitrate/nitrite levels, activities of oxidative enzymes, and plasma levels of proinflammatory cytokines and D-dimer (P < .05).

CONCLUSION

This study clearly showed that APC treatment prevented the delaying effects of remote I/R injury on colonic anastomotic wound healing process. Further clinical studies are required to determine whether APC has a useful role in the enhancement of colonic anastomotic wound healing after particular operations in which I/R injury occurs.

Role of activated protein C on wound healing process in left colonic anastomoses in the presence of intra-abdominal sepsis induced by cecal ligation and puncture: an experimental study in the rat

BACKGROUND

Activated protein C (APC) is a serine protease with anticoagulant and anti-inflammatory activities. The delaying effects of intra-abdominal sepsis on wound healing process in colonic anastomoses have been previously demonstrated. This study was designed to investigate the role of APC on wound healing process in left colonic anastomoses in the presence of intra-abdominal sepsis.

METHODS

The left colonic anastomosis was performed in 48 rats that were divided into four groups: (1) sham-operated group, laparatomy plus cecal mobilization (n = 12); (2) sham + APC group, identical to group I except for APC treatment (n = 12); (3) CLP group, cecal ligation and puncture (n = 12); 4) CLP + APC-treated group, 100 microg/kg, 15 min before the construction of colonic anastomosis (n = 12). Anastomotic bursting pressures were measured in vivo on day 7. Tissue samples were obtained for analyses of hydroxyproline (HP) contents, myeloperoxidase (MPO) acivity, malondialdehyde (MDA), and nitrate/nitrite (NO3(-) /NO2(-)) levels. The plasma levels of tumor necrosis factor alpha (TNF-alpha), interleukin (IL)-6, and D-dimer also were measured.

RESULTS

Intra-abdominal sepsis led to significant decreases in colonic anastomotic bursting pressures and tissue HP contents, along with increases in MPO activity, MDA and NO3(-) /NO2(-) levels, and also plasma levels of TNF-alpha, IL-6, and D-dimer (P < 0.05). However, APC treatment led to significant increases in anastomotic bursting pressures and tissue HP ontents, along with decreases in MPO activity, MDA and NO3(-) /NO2(-) levels, and also plasma levels of TNF-alpha, IL-6, and D-dimer (P < 0.05).

CONCLUSIONS

This study clearly showed that APC treatment prevented the delaying effects of intra-abdominal sepsis on colonic anastomotic wound healing process. Further clinical studies are required to determine whether APC has a useful role in the enhancement of anastomotic healing during particular surgeries in which sepsis-induced injury occurs.

Native Human IFN-αIs a More Potent Suppressor of HDF Response to Profibrotic Stimuli Than Recombinant Human IFN-α

Interferon-alpha(IFN-alpha) inhibits fibroblast proliferation, differentiation into myofibroblasts, and extracellular matrix synthesis, which are key events during both normal wound repair and fibrotic lesion formation. Unlike recombinant human IFN-alpha (rHuIFN-alpha), a native human IFN-alpha (nHuIFN-alpha) consists of several IFN-alpha subtypes and traces of other cytokines produced by the Sendai virus-stimulated human leukocytes. This study compares the antifibrotic effect of nHuIFN-alpha and rHuIFN-alpha in normal human dermal fibroblasts (HDFs). Treatment of HDF culture with nHuIFNA-alpha markedly affects HDF viability, whereas different rHuIFN-alpha subtypes show various effects. Two of twelve rHuIFN-alpha subtypes (IFN-alpha B2 and IFN-alpha K) significantly reduce cell viability of HDFs compared with nontreated HDFs. However, nHuIFN-alpha significantly reduces HDF cell viability in comparison to both nontreated cells and cells treated with rHuIFN-alpha. The 50% inhibitory concentration (IC(50)) varied 10-fold between nHuIFN-alpha and rHuIFN-alpha (1,103 IU/mL and 10,762 IU/mL, respectively). The impact on procollagen type I mRNA synthesis level is comparable at low doses of IFN (100 and 500 IU/mL), whereas at the dose of 1,000 IU/mL, nHuIFN-alpha shows higher repression of collagen type I gene than does rHuIFN-alpha. Both, nHuIFN-alpha and rHuIFN-alpha antagonize the effect of exogenous transforming growth factor-beta (TGF-beta) and interleukin-4 (IL-4) as measured by the alpha-smooth muscle actin (alpha -SMA) and procollagen type I mRNA level, but the effect of nHuIFN-alpha is more pronounced. This study suggests that nHuIFN-alpha is a more potent suppressor of the HDF response to profibrotic stimuli than rHuIFN-alpha, probably because of the synergism between different IFN-alpha subtypes and antifibrotic cytokines and factors.

Overexpression of tumor necrosis factor-alpha diminishes pulmonary fibrosis induced by bleomycin or transforming growth factor-beta

Tumor necrosis factor-alpha (TNF-alpha) is thought to be important in the development of pulmonary fibrosis. However, surfactant protein-C/TNF-alpha transgenic mice do not spontaneously develop pulmonary fibrosis but instead develop alveolar enlargement and loss of elastic recoil. We hypothesized that overexpression of TNF-alpha in the lung requires an additional insult to produce fibrosis. In this study we evaluated whether TNF-alpha overexpression altered the development of pulmonary fibrosis due to bleomycin or transforming growth factor-beta (TGF-beta). Either 0.2 U bleomycin or saline was administered into left lung of TNF-alpha transgenic mice and their transgene-negative littermates. To overexpress TGF-beta, an adenovirus vector containing either active TGF-beta (AdTGF-beta) or LacZ was administered at a dose of 3 x 108 plaque-forming units per mouse. Fibrosis was assessed histologically and by measurement of hydroxyproline. TNF-alpha transgenic mice tolerated bleomycin or AdTGF-beta, whereas the transgene-negative littermates demonstrated severe pulmonary fibrosis after either agent. An increase in prostaglandin E2 and downregulation of TNF receptor I expression were observed in the TNF-alpha transgenic mice. In addition, recombinant human TNF-alpha attenuated bleomycin-induced pulmonary fibrosis. TNF-alpha has a complex role in the development of pulmonary fibrosis. Endogenous TNF-alpha may be important in the development of fibrosis as indicated in other reports, but overexpression of TNF-alpha or exogenous TNF-alpha limits pulmonary fibrosis in mice.

Systemic sclerosis Th2 cells inhibit collagen production by dermal fibroblasts via membrane-associated tumor necrosis factor alpha

OBJECTIVE

In systemic sclerosis (SSc; scleroderma), T cells infiltrate organs undergoing fibrotic changes and may participate in dysregulated production of collagen by fibroblasts. The objective of this study was to functionally characterize T cells infiltrating skin lesions in early SSc and investigate their capacity to affect production of type I collagen and interstitial collagenase (matrix metalloproteinase 1 [MMP-1]) by dermal fibroblasts.

METHODS

Four-color cytometric analysis was used to characterize subset distribution and production of interferon-gamma (IFN gamma) and interleukin-4 (IL-4) in T cell lines generated from the skin of patients with SSc. T cell clones were generated, and their capacity to modulate collagen and MMP-1 production by fibroblasts derived from patients with SSc and from normal individuals was assessed. Neutralizing reagents were used to identify T cell mediators involved in fibroblast modulation.

RESULTS

The skin of individuals with early-stage SSc contained T cells preferentially producing high levels of IL-4. Cloned CD4+ Th2-like cells inhibited collagen production by normal fibroblasts. Th2 cell-dependent inhibition was, at least in part, contact-dependent, was essentially mediated by tumor necrosis factor alpha (TNF alpha), and was dominant over the enhancement induced by profibrotic IL-4 and transforming growth factor beta cytokines. The simultaneous induction of MMP-1 production confirmed the specificity of these observations. To be inhibitory, Th2 cells required activation by CD3 ligation. Th2 cells were less potent than were Th1 cells in inhibiting collagen production by normal fibroblasts via cell-to-cell interaction, and SSc fibroblasts were resistant to inhibition.

CONCLUSION

These findings indicate that, despite their production of IL-4, Th2 cells reduce type I collagen synthesis by dermal fibroblasts because of the dominant effect of TNF alpha, and suggest that strategies based on TNF alpha blockade aimed at controlling fibrosis in SSc may be unwise.

Synergistic enhancement of collagenous protein synthesis by human gingival fibroblasts exposed to nifedipine and TNF-alpha in vitro

BACKGROUND

Gingival overgrowth occurs in patients receiving nifedipine. Gingival inflammation may be an etiologic factor.

METHODS

Gingival fibroblasts were either exposed to (i) 0-500 ng/ml TNF-alpha or 10(-7) M nifedipine or (ii) 0-500 ng/ml TNF-alpha + 10(-7) M nifedipine for 7 days. 3H-proline was used to quantify collagenous protein synthesis.

RESULTS

Both TNF-alpha and 10(-7) M nifedipine significantly decreased cell proliferation, and 10(-7) M nifedipine + 500 ng/ml TNF-alpha reversed these effects. Collagenous protein synthesis was significantly reduced by TNF-alpha and was significantly enhanced by either 10(-7) M nifedipine or 5-500 ng/ml TNF-alpha + 10(-7) M nifedipine.

CONCLUSIONS

Our data report that nifedipine reverses the primary effects of TNF-alpha on collagenous protein synthesis. Patients with gingivitis could be susceptible to gingival overgrowth during nifedipine therapy as a result of synergistic effects of these agents on fibroblast metabolism, which occurs irrespective of reduced cell numbers.

Distinct immune profiles characterize patients with diffuse or limited systemic sclerosis

Mitogen-stimulated IL-2, IFN-gamma, TNF-alpha (type 1 cytokines), and IL-10 (type 2 cytokine) production by peripheral blood mononuclear cells, as well as expression of surface markers on immune cells, was evaluated in systemic sclerosis (SSc) patients. Fifty-four SSc patients with either diffuse (dSSc) or limited (lSSc) disease and 20 age- and sex-matched healthy controls (HCs) were examined. Fourteen patients were treated with prednisone and 9 patients with prednisone and cyclophosphamide pulses. Results showed that (1) IL-2 production is significantly decreased, whereas IL-10 is higher in untreated patients compared to HCs; IL-10, IFN-gamma, and TNF-alpha production is higher in lSSc compared to dSSc patients; (2) CD4+25+ (IL-2R), CD8+, and CD8+45RA-28+57- (memory) lymphocytes are reduced in patients compared to HCs; (3) CD95-expressing CD4+ and CD8+ cells are significantly higher in dSSc patients; and (4) steroids are more effective alone than in combination with cyclophosphamide in reducing IL-10 and IFN-gamma production in these patients. These results confirm that a complex imbalance in cytokine production is present in SSc patients and suggest that peculiar phenotypic populations are underrepresented in these patients. Overexpression of Fas in dSSc could results from the attempt of the immune system to induce apoptosis of autoreactive T-cell clones.

Hypertrophic scar formation following carbon dioxide laser ablation of plantar warts in cyclosporin-treated patients

We present four renal transplant patients who developed hypertrophic scars following carbon dioxide laser ablation of recalcitrant plantar warts. All of the patients were on long-term treatment with cyclosporin, which we believe to be responsible. We discuss several possible mechanisms by which cyclosporin may influence wound healing and scarring.

Understanding the final stages of wound contraction

Much research has been undertaken to improve our understanding of the processes of wound contraction. This article, the second in a two-part series, focuses on granulation tissue modulation.

Cyclooxygenase-2 deficiency results in a loss of the anti-proliferative response to transforming growth factor-beta in human fibrotic lung fibroblasts and promotes bleomycin-induced pulmonary fibrosis in mice

Prostaglandin E(2) (PGE(2)) inhibits fibroblast proliferation and collagen production. Its synthesis by fibroblasts is induced by profibrotic mediators including transforming growth factor (TGF)-beta(1). However, in patients with pulmonary fibrosis, PGE(2) levels are decreased. In this study we examined the effect of TGF-beta(1) on PGE(2) synthesis, proliferation, collagen production, and cyclooxygenase (COX) mRNA levels in fibroblasts derived from fibrotic and nonfibrotic human lung. In addition, we examined the effect of bleomycin-induced pulmonary fibrosis in COX-2-deficient mice. We demonstrate that basal and TGF-beta(1)-induced PGE(2) synthesis is limited in fibroblasts from fibrotic lung. Functionally, this correlates with a loss of the anti-proliferative response to TGF-beta(1). This failure to induce PGE(2) synthesis is because of an inability to up-regulate COX-2 mRNA levels in these fibroblasts. Furthermore, mice deficient in COX-2 exhibit an enhanced response to bleomycin. We conclude that a decreased capacity to up-regulate COX-2 expression and COX-2-derived PGE(2) synthesis in the presence of increasing levels of profibrotic mediators such as TGF-beta(1) may lead to unopposed fibroblast proliferation and collagen synthesis and contribute to the pathogenesis of pulmonary fibrosis.

Overexpression of tumor necrosis factor-alpha produces an increase in lung volumes and pulmonary hypertension

Tumor necrosis factor (TNF)-alpha is a key proinflammatory cytokine that is thought to be important in the development of pulmonary fibrosis, whereas its role in pulmonary emphysema has not been as thoroughly documented. In the present study, TNF-alpha was overexpressed in alveolar type II cells under the control of the human surfactant protein C promoter. In this report, we further characterized the pulmonary abnormalities and provided a physiological assessment of these mice. Histopathology of the lungs revealed chronic inflammation, severe alveolar air space enlargement and septal destruction, and bronchiolitis. However, pulmonary fibrosis was very limited and only seen in the subpleural, peribronchiolar, and perivascular regions. Physiological assessment showed an increase in lung volumes and a decrease in elastic recoil characteristic of emphysema; there was no evidence of restrictive lung disease characteristic of pulmonary fibrosis. In addition, the mice raised in ambient conditions in Denver developed pulmonary hypertension. Gelatinase activity was increased in the lavage fluid from these lungs. These results suggest that in these mice TNF-alpha contributed to the development of pulmonary emphysema through chronic lung inflammation and activation of the elastolytic enzymes but by itself was unable to produce significant pulmonary fibrosis.

Influence of alternatively and classically activated macrophages on fibrogenic activities of human fibroblasts

Activated macrophages regulate fibrogenesis by providing cytokines and growth factors that modulate the proliferation and collagen synthesis of fibroblasts. However, macrophages can be activated in a classical pathway induced by LPS or IFN-gamma and an alternative pathway induced by IL-4 or glucocorticoid. Differently activated macrophages display distinct biological features. To clarify the difference between these two subsets of macrophages in the regulatory mechanisms controlling fibrogenesis, human peripheral blood monocytes were used as the source of macrophages and cocultivation of differently activated macrophages and a fibroblast cell line, WI-38, was performed. Alternatively activated macrophages increased the proliferation index and collagen synthesis of cocultivated WI-38 cells in comparison to untreated monocytes, while classically activated macrophages markedly reduced collagen production of cocultivated WI-38 cells. Additionally, mRNA expression and protein production of TGF-beta(1), PDGF-AA, and PDGF-BB were elevated in alternatively activated macrophages in parallel to their profibrogenic effects. In contrast, expression and production of TNF-alpha, as well as MMP-7, were enhanced in classically activated macrophages. These findings suggested that alternatively activated macrophages enhance fibrogenesis of fibroblasts by providing profibrogenic factors, while classically activated macrophages inhibit fibrogenesis of fibroblasts by releasing antifibrogenic or fibrolytic factors.

Cytokine modulation of type XV collagen gene expression in human dermal fibroblast cultures

The expression of type XV collagen was studied in cultured human dermal fibroblasts exposed to transforming growth factor-beta (TGF-beta), tumor necrosis factor-alpha (TNF-alpha) or interleukin-1beta (IL-1beta), cytokines which have been shown previously to alter the expression of several extracellular matrix genes. TGF-beta enhanced the expression of the type XV collagen gene (COL15A1) in a time-dependent manner, up to 4.3-fold after 24 h of incubation, whereas TNF-alpha and IL-1beta reduced the mRNA steady-state levels by 32 and 80%, respectively. When TGF-beta and TNF-alpha were added together to the cultures, the stimulatory effect of TGF-beta on type XV collagen gene expression was abrogated, indicating antagonistic modulation by these 2 cytokines. These data suggest that the cytokines tested in this study may contribute to the regulation of type XV collagen synthesis in a variety of tissues which have recently been shown to express this particular collagen gene.

The tumor necrosis factor-alpha promoter correlates with progression of primary biliary cirrhosis

BACKGROUND/AIMS

There have been many studies attempting to identify genes that determine susceptibility to primary biliary cirrhosis (PBC), but few studies have attempted to define the genes that modulate the natural history of the disease. There is a biallelic polymorphism, coined TNF1 and TNF2, in the TNFalpha promoter region at -308. We investigated the relative frequency of the TNF1 and TNF2 alleles in patients with PBC, based on the hypothesis that a polymorphism of the TNFalpha promoter region may be associated with the rate of progression and prognosis of PBC.

METHODS

Seventy-one Caucasoid patients with PBC and 133 healthy and unrelated Caucasoid individuals were studied. Genomic DNA was extracted from blood, and the mutation at position -308 of the TNFalpha gene analyzed by PCR and NcoI digestion.

RESULTS

In 71 patients with PBC, 56/71 (78.9%) patients were TNF1/TNF1 homozygotes, 14/71 (19.7%) were TNF1/TNF2 heterozygotes and 1/71 (1.4%) were TNF2/TNF2 homozygotes. In 133 healthy individuals, 109/133 (80.5%) patients were TNF1/TNF1 homozygotes, 24/133 (18%) were TNF1/TNF2 heterozygotes. No control individuals were TNF2/TNF2 homozygotes. The difference between the two groups was not statistically significant (p = 0.3684). However, in patients with TNF1/TNF1 the Mayo score for disease severity was 4.596+/-0.157 (mean +/- SEM), compared to 5.637+/-0.420 for patients with TNF1/TNF2. This Mayo score was significantly higher in patients with the TNF1/TNF2 genotype than those with TNF1/TNF1 (p = 0.0140), with an odds ratio of 4.9.

CONCLUSIONS

Our data demonstrate that the presence of the TNF2 allele may be associated with a higher Mayo score, and thus with patients in a more advanced clinical stage. These data have both theoretical and clinical implications.

Transfer of tumor necrosis factor-alpha to rat lung induces severe pulmonary inflammation and patchy interstitial fibrogenesis with induction of transforming growth factor-beta1 and myofibroblasts

Tumor necrosis factor-alpha is up-regulated in a variety of different human immune-inflammatory and fibrotic pulmonary pathologies. However, its precise role in these pathologies and, in particular, the mechanism(s) by which it may induce fibrogenesis are not yet elucidated. Using a replication-deficient adenovirus to transfer the cDNA of tumor necrosis factor-alpha to rat lung, we have been able to study the effect of transient but prolonged (7 to 10 days) overexpression of tumor necrosis factor-alpha in normal adult pulmonary tissue. We have demonstrated that local overexpression resulted in severe pulmonary inflammation with significant increases in neutrophils, macrophages, and lymphocytes and, to a lesser extent, eosinophils, with a peak at day 7. By day 14, the inflammatory cell accumulation had declined, and fibrogenesis became evident, with fibroblast accumulation and deposition of extracellular matrix proteins. Fibrotic changes were patchy but persisted to beyond day 64. To elucidate the mechanism underlying this fibrogenesis, we examined bronchoalveolar fluids for the presence of the fibrogenic cytokine transforming growth factor-beta1 and tissues for induction of alpha-smooth muscle actin-rich myofibroblasts. Transforming growth factor-beta1 was transiently elevated from day 7 (peak at day 14) immediately preceding the onset of fibrogenesis. Furthermore, there was a striking accumulation of myofibroblasts from day 7, with the most extensive and intense immunostaining at day 14, ie, coincident with the up-regulation of transforming growth factor-beta1 and onset of fibrogenesis. Thus, we have provided a model of tumor necrosis factor-alpha-mediated pulmonary inflammation and fibrosis in normal adult lung, and we suggest that the fibrogenesis may be mediated by the secondary up-regulation of transforming growth factor-beta1 and induction of pulmonary myofibroblasts.

Enhancement of fibroblast collagenase (matrix metalloproteinase-1) gene expression by ceramide is mediated by extracellular signal-regulated and stress-activated protein kinase pathways

Inflammatory cytokines tumor necrosis factor-alpha and interleukin-1 trigger the ceramide signaling pathway, initiated by neutral sphingomyelinase-elicited hydrolysis of cell membrane phospholipid sphingomyelin to ceramide, a new lipid second messenger. Here, we show that triggering the ceramide pathway by sphingomyelinase or C2- and C6-ceramide enhances collagenase-1 (matrix metalloproteinase-1; MMP-1) gene expression by fibroblasts. C2-ceramide activates three distinct mitogen-activated protein kinases (MAPKs) in dermal fibroblasts, i.e. extracellular signal-regulated kinase 1/2 (ERK1/2), stress-activated protein kinase/Jun N-terminal-kinase (SAPK/JNK), and p38. Stimulation of MMP-1 promoter activity by C2-ceramide is dependent on the presence of a functional AP-1 cis-element and is entirely inhibited by overexpression of MAPK inhibitor, dual specificity phosphatase CL100 (MAPK phosphatase-1). Activation of MMP-1 promoter by C2-ceramide is also effectively inhibited by kinase-deficient forms of ERK1/2 kinase (MEK1/2) activator Raf-1, ERK1 and ERK2, SAPK/JNK activator SEK1, or SAPKbeta. In addition, ceramide-dependent induction of MMP-1 expression is potently prevented by PD 98059, a selective inhibitor of MEK1 activation, and by specific p38 inhibitor SB 203580. These results show that triggering the ceramide signaling pathway activates MMP-1 gene expression via three distinct MAPK pathways, i.e. ERK1/2, SAPK/JNK, and p38, and suggest that targeted modulation of the ceramide signaling pathway may offer a novel therapeutic approach for inhibiting collagenolytic activity, e.g. in inflammatory disorders.

Schwann cell extracellular matrix protein production is modulated by Mycobacterium leprae and macrophage secretory products

Extracellular matrix (ECM) protein deposition is an important feature of leprous nerves, where Schwann cells (SCs) and macrophages are the main hosts for Mycobacterium leprae. Since, SCs are involved in the synthesis of ECM proteins and its production is regulated by macrophage secretory factors, the present study aimed to determine in vitro, the effect of M. leprae infection and macrophage secretory products on secretion of ECM proteins by SCs in two strains of mice, Swiss White (SW) and C57BL/6, that are known to differ in their nerve pathology and macrophage functions in response to infection. Following six days of M. leprae infection, SCs from SW mice responded with increased secretion of 14C-leucine radiolabelled proteins and a concomitant increase in laminin and collagens type I, III and IV, as determined by enzyme-linked immunosorbent assay. In contrast infected C57BL/6 SCs responded with decreased secretion of total proteins and fibronectin. Exposure of SCs to macrophage conditioned medium resulted in decreased ECM protein secretion in both strains of mice. This decrease was a function of protein breakdown by macrophage derived proteases and also active regulation by macrophage secreted cytokines. A similar effect of M. leprae and macrophage secretory products on SC metabolism in leprous nerves would have major ramifications on damage and repair activities. In addition ECM proteins would also influence the composition of the infiltrating cell population in lepromatous and tuberculoid nerves.

Increased release of tumour necrosis factor-alpha in human tear fluid after excimer laser induced corneal wound

AIMS

To measure the pre- and postoperative tear fluid tumour necrosis factor-alpha (TNF-alpha) concentration and release in patients undergoing excimer laser photorefractive keratectomy (PRK).

METHODS

Tear fluid samples from 18 PRK patients were collected with scaled microcapillary tubes preoperatively (day 0), on the second (day 2), and on the seventh (day 7) postoperative days. The TNF-alpha concentration was measured using a double antibody radioimmunoassay, and the TNF-alpha release was calculated by multiplying the concentration by the tear fluid flow in the collection capillary.

RESULTS

The mean tear fluid flow in the capillary was 22.5 microliters/min (range 1.5-93.2) on day 0, 80.7 microliters/min (3.0-219, p = 0.0002) on day 2, and 14.6 microliters/min (1.8-41.7, NS) on day 7. The mean TNF-alpha concentration and release values were: day 0, 358 ng/I (110-680) and 9.5 pg/min (0.2-37.5, NS); day 2, 417 ng/l (< 5-750, NS) and 28.6 pg/min (0.6-81.5; p = 0.003); and day 7, 320 ng/I (< 5-735, NS) and 4.8 pg/min (0-25.4, NS), respectively.

CONCLUSION

TNF-alpha appears to be a component of normal tear fluid. In spite of hypersecretion caused by the corneal wound, TNF-alpha concentrations remain constant during wound healing. TNF-alpha release increases significantly during the 2 postoperative days following PRK, suggesting a role in corneal wound healing.

Pathogenesis of scleroderma. Collagen

It is now evident that persistent overproduction of collagen and other connective tissue macromolecules results in excessive tissue deposition, and is responsible for the progressive nature of fibrosis in SSc. Up-regulation of collagen gene expression in SSc fibroblasts appears to be a critical event in the development of tissue fibrosis. The coordinate transcriptional activation of a number of extracellular matrix genes suggests a fundamental alteration in the regulatory control of gene expression in SSc fibroblasts. Trans-acting nuclear factors that bind to cis-acting elements in enhancer and promoter regions of the genes modulate the basal and inducible transcriptional activity of the collagen genes. The identity of the nuclear transcriptional factors that regulate normal collagen gene expression remains to be firmly established, and to date, no alterations in the level or in the activity of such DNA binding factors has been demonstrated in SSc fibroblasts. In addition to important interactions between fibroblasts and the extracellular matrix, cytokines and other cellular mediators can positively and negatively influence fibroblast collagen synthesis. Some of these signaling molecules may have physiologic roles, and their aberrant expression, or altered responsiveness of SSc fibroblasts to them, may result in the acquisition of the activated phenotype. The rapid expansion of knowledge regarding the effects of cytokines on extracellular matrix synthesis has led to an appreciation of the enormous complexity of regulatory networks that operate in the physiologic maintenance of connective tissue and which may be responsible for the occurrence of pathologic fibrosis. The ubiquitous growth factor TGF beta is the most potent inducer of collagen gene expression and connective tissue accumulation yet discovered. The expression of TGF beta in activated infiltrating mononuclear cells suggests a role for this cytokine as a mediator of fibroblast activation in SSc. Furthermore, the recognition that TGF beta is capable of inducing its own expression in a variety of cell types, coupled with the demonstration that a subpopulation of SSc dermal fibroblasts produces TGF beta, indicates the existence of a possible autocrine loop whereby lymphocyte-derived TGF beta in early SSc not only signals biosynthetic activation of fibroblasts in a paracrine manner, but autoinduces endogenous TGF beta production by the target fibroblasts themselves. Such an autocrine loop involving TGF beta may explain the persistent activation of collagen gene expression in SSc fibroblasts, and could be responsible for the progressive nature of fibrosis in SSc. Numerous other cytokines, as well as cell-matrix interactions, also modify collagen gene expression and can significantly influence the effects of TGF beta. Although their physiologic function in tissue remodeling or their involvement in abnormal fibrogenesis has not yet been conclusively demonstrated, the study of the biologic effects of these cytokines may provide important clues to understanding the pathogenesis of SSc, and to the development of rational drug therapy aimed at interrupting the abnormal fibrogenic process in this disease.

Tumor necrosis factor-alpha inhibits collagen synthesis in human and rat granulation tissue fibroblasts

The purpose of the study was to examine the effects of tumor necrosis factor-alpha (TNF-alpha) on collagen gene expression in rat and human granulation tissue fibroblast cultures. The cells were exposed to 0.1, 1, 10, or 100 ng/ml of TNF-alpha, and the rate of collagen synthesis was measured as synthesis of protein-bound 3H-hydroxy-proline. Total cellular RNA was isolated from fibroblasts, and measurements of specific cellular RNAs from fibroblasts were performed by Northern blot hybridizations using 32P-labeled cDNA probes. In cultures of rat granulation tissue fibroblasts TNF-alpha decreased 3H-hydroxyproline production to about 75% of that in controls and it also decreased pro alpha 1(I) and pro alpha 1(III) collagen mRNA levels, maximally to 33% and 23% of the control levels, respectively. In cultures of human granulation tissue fibroblasts a similar inhibiting effect in the production of collagen was seen. TNF-alpha decreased the production of 3H-hydroxyproline to 56% of the control value with a dose of 100 ng/ml also having an inhibiting effect on pro alpha 1(I) collagen mRNA levels of up to 43% of the control level. However, no effect was seen on pro alpha 1(III) collagen mRNA levels.

Regulation of keratinocyte growth factor gene expression in human skin fibroblasts

Human keratinocyte growth factor (KGF) is a recently identified mitogen for epithelial cells produced by normal stromal fibroblasts. KGF has been shown to stimulate keratinocyte migration and promote re-epithelialization of skin suggesting a critical role for KGF in wound healing. To understand how KGF might be regulated during wound healing, we examined the ability of the pro-inflammatory cytokines interleukin-1 alpha (IL-1 alpha), interleukin-1 beta (IL-1 beta) interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha) transforming growth factor-beta 1 (TGF-beta 1) and interferon-gamma (IFN-gamma) to modulate KGF gene expression in cultured human fibroblasts, using northern blot analysis. Exposure to IL-1 alpha (20 units/ml) or IL-1 beta (100 units/ml) for 24 h increased KGF mRNA expression by 352% and 504%, respectively, with early induction seen at 2 h and maximal induction seen at 8 h. TNF-alpha (30 ng/ml) increased KGF mRNA expression by 535% at 24 h, with induction first seen at 8 h. The maximal induction of KGF mRNA was observed when IL-1 alpha, IL-1 beta and TNF-alpha were used at 100 units/ml, and 3 ng/ml, respectively, although concentrations 100-500-fold lower (IL-1 alpha, 0.02 units/ml; IL-beta, 0.02 units/ml; and TNF-alpha, 0.03 ng/ml) were nearly as stimulatory, increasing KGF mRNA expression by 175%, 254% and 322%, respectively. IL-6 (200 units/ml), TGF-beta 1 (5 ng/ml) and IFN-gamma (200 units/ml) did not change the level of KGF mRNA at 24 h in human fibroblasts under the same conditions. The protein synthesis inhibitor cycloheximide abrogated the effects of IL-1 alpha, IL-1 beta and TNF-alpha on KGF gene induction, indicating that new protein synthesis is required in the process. Dexamethasone (10(-7) M), known to inhibit inflammatory reactions and retard wound healing, also inhibited the induction of KGF mRNA expression by IL-1 alpha, IL-1 beta and TNF-alpha. Individual variation in KGF mRNA expression was see when fibroblasts from different aged donors were analysed, but no consistent age-associated change was observed. These results suggest that IL-1 alpha, IL-1 beta and TNF-alpha up-regulate KGF gene expression in fibroblasts and might be responsible for its induction following skin wounding or other injury.

TNF-R55-specific form of human tumor necrosis factor-alpha induces collagenase gene expression by human skin fibroblasts

Tumor necrosis factor-alpha (TNF-alpha) is a potent inhibitor of connective tissue formation. The cellular effects of TNF-alpha are mediated by two distinct cell-surface receptors, TNF-R55 and TNF-R75, both present on various types of cells, including fibroblasts. In this study we wanted to elucidate the role of TNF-R55 as a mediator of the connective tissue effects of TNF-alpha by using a mutant, TNF-R55-specific form of human TNF-alpha. This mutant TNF-alpha markedly induced collagenase and stromelysin-1 gene expression in dermal fibroblasts, the maximal activation (up to 42-fold) being 65%-89% of that noted with wild-type human TNF-alpha. In addition, TNF-R55-specific TNF-alpha suppressed type I collagen mRNA levels as potently as wild-type TNF-alpha (by 60%). The enhancement of collagenase gene expression by TNF-R55-specific TNF-alpha was augmented by simultaneous treatment of normal and scleroderma skin fibroblasts with interferon-gamma, indicating specific enhancement of TNF-R55 signaling pathway by interferon-gamma. These results show that stimulation of the TNF-R55 signaling pathway is sufficient for the inhibitory effects of TNF-alpha on extracellular matrix formation by dermal fibroblasts. It is conceivable that due to reduced systemic toxicity, TNF-R55-specific forms of human TNF-alpha may prove to be feasible in the therapy of fibrotic disorders.

Transcriptional regulation of decorin gene expression. Induction by quiescence and repression by tumor necrosis factor-alpha

Decorin, a leucine-rich proteoglycan with ubiquitous tissue distribution, may play essential biological roles during inflammation and cancer growth through its ability to bind extracellular matrix constituents and growth factors. In this study, we demonstrate that decorin gene expression is greatly enhanced after normal diploid fibroblasts reach confluency and cease to proliferate. Elevation of decorin mRNA steady state levels was maintained for up to 16 days postconfluency. In vitro transcription analyses indicated enhanced transcriptional activity in quiescent fibroblasts when compared to cells harvested in their logarithmic phase of growth. This phenotypic trait was reversed by the exogenous addition of tumor necrosis factor-alpha (TNF-alpha). Furthermore, transforming growth factor-beta (TGF-beta) down-regulated decorin gene expression in an additive manner with TNF-alpha. Transient cell transfection assays using plasmid constructs harboring the decorin promoter linked to the chloramphenicol acetyltransferase reporter gene demonstrated a dose-dependent transcriptional repression by TNF-alpha. These findings were further corroborated by in vitro transcription experiments using nuclear extracts from control and TNF-alpha-treated quiescent fibroblasts. In contrast, the decorin promoter constructs failed to respond to TGF-beta, thus suggesting either post-transcriptional regulation by this growth factor or lack of TGF-beta-responsive elements. Further experiments with 5' deletion constructs showed two TNF-alpha response elements, one residing within the 5'-untranslated region (exon Ib), the other one between residues -188 and -140 of the decorin promoter. Collectively, our results indicate that TNF-alpha, through its ability to transcriptionally inhibit decorin gene expression in growth-arrested cells, may be a key modulator of the biological functions of this proteoglycan.

Reciprocal induction of tumor necrosis factor-alpha and interleukin-1 beta activity mediates fibronectin synthesis in coronary artery smooth muscle cells

We previously demonstrated an immune-inflammatory response associated with increased expression of interleukin (IL)-1 beta and fibronectin in graft coronary arteriopathy in piglets following heterotopic heart transplant. Further studies showed that increased endogenously produced IL-1 beta was upregulating fibronectin production by donor coronary artery (CA) smooth muscle cells (SMC). Since co-induction of IL-1 beta and tumor necrosis factor (TNF)-alpha has been shown in other systems, we investigated the possible interaction between these cytokines in regulating fibronectin production in CA SMC. First, we documented increased TNF-alpha expression in vivo in donor compared to host CA. Next, synthesis of fibronectin was measured in host and donor CA SMC following [35S]-methionine radiolabeling and gelatin-sepharose extraction. As previously shown with IL-1 beta, increased donor CA SMC fibronectin synthesis was reduced to host levels in the presence of TNF-alpha antibodies, and exogenous TNF-alpha upregulated fibronectin synthesis in host CA SMC to levels in donor cells. In normal CA SMC, TNF-alpha-stimulated fibronectin production was downregulated to or below control levels in the presence of IL-1 beta antibodies. Likewise, IL-1 beta-stimulated fibronectin synthesis was downregulated to control levels when TNF-alpha neutralizing antibodies were added. Combining TNF-alpha and IL-1 beta enhanced fibronectin production over that observed with either cytokine alone, but was not additive. Thus, our studies suggest that vascular SMC fibronectin synthesis is regulated by reciprocal induction of IL-1 beta and TNF-alpha activity and provide the first demonstration of a 'cytokine loop' modulating matrix production.

Modulation of rabbit articular chondrocyte (RAC) proliferation by TGF-beta isoforms

We have previously shown that TGF-beta 1 exerts a bifunctional effect on RAC proliferation. Added to quiescent cultures, it inhibits the entry of G0/G1 cells into S phase whereas in S phase synchronized populations, it stimulates the DNA replication rate with a delayed G2 + M phase and a subsequent transient increase of cell number. As TGF-beta 2 and beta 3 isoforms are also expressed in bone and cartilage tissues, it was of interest to study their effect on RAC proliferation, in comparison to that of TGF-beta 1. Using cell counting and tritiated thymidine incorporation, we found that all the TGF-beta s used here induced an increase of RAC proliferation rate occurring between 24 and 48 h of exposure. TGF-beta 2 appeared as the most efficient form as judged from the maximum of thymidine labelling. However, TGF-beta 3 induced an increase of cell number slightly higher than both TGF-beta 1 and TGF-beta 2 (+30% versus 20% for TGF-beta 1 and beta 2). TGF-beta 2 and beta 3 were able to stimulate the DNA replication rate as previously demonstrated for TGF-beta 1. However, the effect occurred later for TGF-beta 2 and beta 3 (12 h) than for TGF-beta 1 (6 h). This was confirmed by flow cytometric analysis of DNA content. In addition, immunodetection by flow cytometry demonstrated that all TGF-beta isoforms enhanced endogenous expression of TGF-beta-related peptides. The effect was shown to be associated with the cell cycle S phase and was greater for TGF-beta 3 than for TGF-beta 1 and beta 2. These findings suggest that TGF-beta s could act on RAC functions via autocrine and paracrine ways. Taken together, these data indicate that TGF-beta s may modulate proliferation of articular chondrocytes and therefore could play a role in the activation of these cells in the early stages of osteoarthritis.