Altered immunohistochemical localization of basic fibroblast growth factor after bleomycin-induced lung injury

Basic fibroblast growth factor protects against influenza A virus-induced acute lung injury by recruiting neutrophils

Influenza virus (IAV) infection is a major cause of severe respiratory illness that affects almost every country in the world. IAV infections result in respiratory illness and even acute lung injury and death, but the underlying mechanisms responsible for IAV pathogenesis have not yet been fully elucidated. In this study, the basic fibroblast growth factor 2 (FGF2) level was markedly increased in H1N1 virus-infected humans and mice. FGF2, which is predominately derived from epithelial cells, recruits and activates neutrophils via the FGFR2-PI3K-AKT-NFκB signaling pathway. FGF2 depletion or knockout exacerbated influenza-associated disease by impairing neutrophil recruitment and activation. More importantly, administration of the recombinant FGF2 protein significantly alleviated the severity of IAV-induced lung injury and promoted the survival of IAV-infected mice. Based on the results from experiments in which neutrophils were depleted and adoptively transferred, FGF2 protected mice against IAV infection by recruiting neutrophils. Thus, FGF2 plays a critical role in preventing IAV-induced lung injury, and FGF2 is a promising potential therapeutic target during IAV infection.

Fibroblast growth factor 2 decreases bleomycin-induced pulmonary fibrosis and inhibits fibroblast collagen production and myofibroblast differentiation

Fibroblast growth factor (FGF) signaling has been implicated in the pathogenesis of pulmonary fibrosis. Mice lacking FGF2 have increased mortality and impaired epithelial recovery after bleomycin exposure, supporting a protective or reparative function following lung injury. To determine whether FGF2 overexpression reduces bleomycin-induced injury, we developed an inducible genetic system to express FGF2 in type II pneumocytes. Double-transgenic (DTG) mice with doxycycline-inducible overexpression of human FGF2 (SPC-rtTA;TRE-hFGF2) or single-transgenic controls were administered intratracheal bleomycin and fed doxycycline chow, starting at either day 0 or day 7. In addition, wild-type mice received intratracheal or intravenous recombinant FGF2, starting at the time of bleomycin treatment. Compared to controls, doxycycline-induced DTG mice had decreased pulmonary fibrosis 21 days after bleomycin, as assessed by gene expression and histology. This beneficial effect was seen when FGF2 overexpression was induced at day 0 or day 7 after bleomycin. FGF2 overexpression did not alter epithelial gene expression, bronchoalveolar lavage cellularity or total protein. In vitro studies using primary mouse and human lung fibroblasts showed that FGF2 strongly inhibited baseline and TGFβ1-induced expression of alpha smooth muscle actin (αSMA), collagen, and connective tissue growth factor. While FGF2 did not suppress phosphorylation of Smad2 or Smad-dependent gene expression, FGF2 inhibited TGFβ1-induced stress fiber formation and serum response factor-dependent gene expression. FGF2 inhibition of stress fiber formation and αSMA requires FGF receptor 1 (FGFR1) and downstream MEK/ERK, but not AKT signaling. In summary, overexpression of FGF2 protects against bleomycin-induced pulmonary fibrosis in vivo and reverses TGFβ1-induced collagen and αSMA expression and stress fiber formation in lung fibroblasts in vitro, without affecting either inflammation or epithelial gene expression. Our results suggest that in the lung, FGF2 is antifibrotic in part through decreased collagen expression and fibroblast to myofibroblast differentiation. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

The Effect of Topical Corticosteroid on Basic Fibroblast Growth Factor in Nasal Polyp Tissue

Background

The etiology of nasal polyposis and pathophysiological mechanisms of polyp formation is still poorly understood. Experimental models have suggested that nasal polyp growth requires extracellular matrix formation and is associated with fibroblast proliferation. Intranasal corticosteroids appear to be useful in reducing nasal polypoid lesions and the likelihood of polyp recurrence after surgery. Basic fibroblast growth factor (bFGF) is a potent angiogenesis factor and is mitogenic for a wide range of cell types. We investigated the alteration of bFGF levels in nasal polyp tissue after administration of topical corticosteroid.

Methods

Nasal polyp tissues were obtained from 36 patients with diffuse nasal polyposis before and after topical nasal steroid treatment. As a topical nasal steroid mometasone furoate was given for 4 weeks in a dosage of 200 μg/day. The bFGF levels were measured by competitive enzyme immunoassay method.

Results

The mean levels of tissue bFGF, before and after topical nasal steroid treatment, were 1485 ± 826 ng/mg protein (range, 416–3434 ng/mg) and 1340 ± 749 ng/mg protein (range, 330–3288 ng/mg), respectively. The levels of bFGF in nasal polyps were significantly lower than those before treatment after administration of topical nasal steroid (p = 0.011).

Conclusion

Administration of topical nasal steroid decreases bFGF levels of nasal polyp. It may be suggested that one of the effects in diminishing the size of nasal polyps is by decreasing the bFGF.

Fibroblast growth factor 2 is required for epithelial recovery, but not for pulmonary fibrosis, in response to bleomycin

The pathogenesis of pulmonary fibrosis involves lung epithelial injury and aberrant proliferation of fibroblasts, and results in progressive pulmonary scarring and declining lung function. In vitro, fibroblast growth factor (FGF) 2 promotes myofibroblast differentiation and proliferation in cooperation with the profibrotic growth factor, transforming growth factor-β1, but the in vivo requirement for FGF2 in the development of pulmonary fibrosis is not known. The bleomycin model of lung injury and pulmonary fibrosis was applied to Fgf2 knockout (Fgf2(-/-)) and littermate control mice. Weight loss, mortality, pulmonary fibrosis, and histology were analyzed after a single intranasal dose of bleomycin. Inflammation was evaluated in bronchoalveolar lavage (BAL) fluid, and epithelial barrier integrity was assessed by measuring BAL protein and Evans Blue dye permeability. Fgf2 is expressed in mouse and human lung epithelial and inflammatory cells, and, in response to bleomycin, Fgf2(-/-) mice have significantly increased mortality and weight loss. Analysis of BAL fluid and histology show that pulmonary fibrosis is unaltered, but Fgf2(-/-) mice fail to efficiently resolve inflammation, have increased BAL cellularity, and, importantly, deficient recovery of epithelial integrity. Fgf2(-/-) mice similarly have deficient recovery of club cell secretory protein(+) bronchial epithelium in response to naphthalene. We conclude that FGF2 is not required for bleomycin-induced pulmonary fibrosis, but rather is essential for epithelial repair and maintaining epithelial integrity after bleomycin-induced lung injury in mice. These data identify that FGF2 acts as a protective growth factor after lung epithelial injury, and call into question the role of FGF2 as a profibrotic growth factor in vivo.

The controversial role of mast cells in tumor growth

Mast cells (MCs) were first described by Paul Ehrlich (Beiträge zur Theorie und Praxis der Histologischen Färbung, Thesis, Leipzig University, 1878). They have long been implicated in the pathogenesis of allergic reactions and protective responses to parasites. However, their functional role has been found to be complex and multifarious. MCs are also involved in various cell-mediated immune reactions and found in tissues from multiple disease sites, and as a component of the host reaction to bacteria, parasite, and even virus infections. They also participate in angiogenic and tissue repair processes after injury. The importance of a possible functional link between chronic inflammation and cancer has long been recognized. As most tumors contain inflammatory cell infiltrates, which often include plentiful MCs, a possible contribution of these cells to tumor development has emerged. In this review, general biology of mast cells, their development, anatomical distribution, and phenotype as well as their secretory products will first be discussed. The specific involvement of MCs in tumor biology and tumor fate will then be considered, with particular emphasis on their capacity to stimulate tumor growth by promoting angiogenesis and lymphangiogenesis. Finally, it is suggested that mast cells may serve as a novel therapeutic target for cancer treatment.

Molecular profile of the antrochoanal polyp: up-regulation of basic fibroblast growth factor and transforming growth factor beta in maxillary sinus mucosa

BACKGROUND

Various pathogenetic mechanisms have been proposed to explain the development of antrochoanal polyps (ACPs); however, the cause is still largely unknown. The aim of this study was to characterize the expression and the potential role of a battery of molecular markers in the development of ACPs. A prospective controlled study of a case series was performed.

METHODS

Tissue samples of maxillary sinus mucosa were obtained from 14 patients with ACPs, 17 patients with chronic nonpolypoid maxillary sinusitis, and 4 patients with normal maxillary sinus mucosa; RNAs were extracted from the sinus mucosa, and semiquantitative reverse transcription-polymerase chain reaction was performed for basic fibroblast growth factor, transforming growth factor P, and mucin genes (MUC), MUC5AC, MUC5B, and MUC8, to investigate their expression.

RESULTS

The expression of basic fibroblast growth factor and transforming growth factor beta was significantly higher in ACPs than in chronic rhinosinusitis and healthy mucosa. Meanwhile, the levels of expression of MUC genes were higher in ACPs and chronic rhinosinusitis compared with healthy mucosa.

CONCLUSION

These findings suggest that ACPs may represent an inflammatory reaction caused by overproduction of tissue-derived growth factors in an inductive environment.

Chronic obstructive pulmonary disease is associated with enhanced bronchial expression of FGF-1, FGF-2, and FGFR-1

An important feature of chronic obstructive pulmonary disease (COPD) is airway remodelling, the molecular mechanisms of which are poorly understood. In this study, the role of fibroblast growth factors (FGF-1 and FGF-2) and their receptor, FGFR-1, was assessed in bronchial airway wall remodelling in patients with COPD (FEV1 < 75%; n = 15) and without COPD (FEV1 > 85%; n = 16). FGF-1 and FGFR-1 were immunolocalized in bronchial epithelium, airway smooth muscle (ASM), submucosal glandular epithelium, and vascular smooth muscle. Quantitative digital image analysis revealed increased cytoplasmic expression of FGF-2 in bronchial epithelium (0.35 +/- 0.03 vs 0.20 +/- 0.04, p < 0.008) and nuclear localization in ASM (p < 0.0001) in COPD patients compared with controls. Elevated levels of FGFR-1 in ASM (p < 0.005) and of FGF-1 (p < 0.04) and FGFR-1 (p < 0.001) in bronchial epithelium were observed. In cultured human ASM cells, FGF-1 and/or FGF-2 (10 ng/ml) induced cellular proliferation, as shown by [3H]thymidine incorporation and by cell number counts. Steady-state mRNA levels of FGFR-1 were elevated in human ASM cells treated with either FGF-1 or FGF-2. The increased bronchial expression of fibroblast growth factors and their receptor in patients with COPD, and the mitogenic response of human ASM cells to FGFs in vitro suggest a potential role for the FGF/FGFR-1 system in the remodelling of bronchial airways in COPD.

Vascular endothelial growth factor, fibroblast growth factor 2, platelet derived growth factor and transforming growth factor beta released in human dental pulp following orthodontic force

OBJECTIVE

The release of four diffusible angiogenic growth factors in human dental pulp following orthodontic force was investigated by using neutralising growth factor antibodies (NAs), individually and in four different combinations to block their effects. This study investigated if increasing the number of NAs (anti h vascular endothelial growth factor (VEGF), anti h fibroblast growth factor (FGF2), anti h platelet derived growth factor (PDGF) and anti Transforming growth factor beta (TGFbeta)) in combination resulted in a progressive reduction of the angiogenic response of the pulp.

MATERIALS AND METHODS

The dental pulps from two groups of 40 premolar teeth, four teeth from each of 20 patients treated with fixed appliances for 2 weeks, were divided vertically, and sections from each half pulp co-cultured with sections of rat aorta in collagen. In one group, one of each of the four NAs, and in the other group, one of the four different NA combinations were added to the media of the co-cultures from one half of the pulp from each of the four teeth of each patient; the other half pulp co-cultures were controls. Cultures were examined daily by light microscopy for growth and number of microvessels.

RESULTS

NAs significantly reduced microvessel numbers in the co-cultures when added individually (P<0.004), and in each of the four combinations (P<0.002), with a trend to progressively reduced microvessel numbers with increasing number of NAs in combination.

CONCLUSIONS

Results indicated that all four angiogenic growth factors examined were released following orthodontic force application and play a role in the angiogenic response of the pulp, and that these factors may be more effective in combination.

Retrovirally introduced prostaglandin D2 synthase suppresses lung injury induced by bleomycin

Hematopoietic prostaglandin D synthase (PGDS) is a key enzyme to produce prostaglandin (PG) D and J series. These PGs are involved in inflammation and immune system. The PGDS complementary DNA (cDNA)-expressing retrovirally transfected fibroblasts were introduced in vivo, and effect of the expression on lung injury induced by bleomycin was investigated in mice. Intravenous injection of PGDS cDNA-expressing fibroblasts significantly reduced lung edema, leukocyte infiltration in bronchoalveolar lavage (BAL) fluid, and pulmonary collagen content at 4 wk after instillation of bleomycin. Survival rate in mice instilled with the PGDS-expressing fibroblasts was higher than that in mice that received the mock transfection. Administration of 15-deoxy-Delta 12,14-PGJ2, which is a nonenzymatic metabolite of PGD2, also attenuated the lung injury, suggesting mediation of PGs produced by PGDS for the attenuation. Introduction of PGDS cDNA-expressing fibroblasts suppressed expression of basic fibroblast growth factor, connective tissue growth factor, and collagen messenger RNAs in the lungs, as well as the levels of total proteins and hemoglobin in BAL fluid. These data suggest that the suppressive effect of PGDS on the lung injury could be partly mediated by edema formation and inhibition of genes involved in the fibrotic change.

Enhanced expression of fibroblast growth factors and receptor FGFR-1 during vascular remodeling in chronic obstructive pulmonary disease

Important characteristics of chronic obstructive pulmonary disease (COPD) include airway and vascular remodeling, the molecular mechanisms of which are poorly understood. We assessed the role of fibroblast growth factors (FGF) in pulmonary vascular remodeling by examining the expression pattern of FGF-1, FGF-2, and the FGF receptor (FGFR-1) in peripheral area of lung tissues from patients with COPD (FEV(1) < or = 75%; n = 15) and without COPD (FEV(1) > or = 85%; n = 13). Immunohistochemical staining results were evaluated by digital video image analysis as well as by manual scoring. FGF-1 and FGFR-1 were detected in vascular smooth muscle (VSM), airway smooth muscle, and airway epithelial cells. FGF-2 was localized in the cytoplasm of airway epithelium and in the nuclei of airway smooth muscle, VSM, and endothelial cells. In COPD cases, an unequivocal increase in FGF-2 expression was observed in VSM (3-fold, P = 0.001) and endothelium (2-fold, P = 0.007) of small pulmonary vessels with a luminal diameter under 200 micro m. In addition, FGFR-1 levels were elevated in the intima (1.5-fold, P = 0.05). VSM cells of large (> 200 micro m) pulmonary vessels showed increased staining for FGF-1 (1.6-fold, P < 0.03) and FGFR-1 (1.4-fold, P < 0.04) in COPD. Pulmonary vascular remodeling, assessed as the ratio of alpha-smooth muscle actin staining and vascular wall area with the lumen diameter, was increased in large vessels of patients with COPD (P = 0.007) and was inversely correlated with FEV(1) values (P < 0.007). Our results suggest an autocrine role of the FGF-FGFR-1 system in the pathogenesis of COPD-associated vascular remodeling.

Basic fibroblast growth factor and its receptors in idiopathic pulmonary fibrosis and lymphangioleiomyomatosis

Basic fibroblast growth factor (bFGF) is a potent mitogenic factor for smooth muscle cells, myofibroblasts, and fibroblasts, proliferation of which is a hallmark of idiopathic pulmonary fibrosis (IPF) and lymphangioleiomyomatosis (LAM). Mast cells produce bFGF and have been associated with pulmonary fibrosis. We hypothesize that smooth muscle cell/myofibroblast-like cells will be spatially associated with bFGF-containing mast cells and that bFGF receptors will be expressed on the effector cells in IPF and LAM. We performed quantitative immunohistochemistry for bFGF, mast cell tryptase, smooth muscle actin for smooth muscle cell/myofibroblast-like cells, and fibroblast growth factor receptors (Flg, Bek) and measured collagen and elastic fiber in lung sections from IPF (n = 14), LAM (n = 9), and control lung (n = 10). IPF and LAM lung contained more smooth muscle cell/myofibroblast-like cells than did control lung. bFGF-containing mast cells were abundant both in IPF and LAM and were associated with collagen, elastic fibers, and smooth muscle cell/myofibroblast-like cells in IPF. Flg was expressed on epithelial cells, endothelial cells, smooth muscle cell/myofibroblast-like cells, and macrophages in IPF. In LAM, Flg was expressed on epithelial cells adjacent to smooth muscle cell/myofibroblast-like cell aggregates. Bek was expressed dominantly on smooth muscle cell/myofibroblast-like cells in LAM and on smooth muscle cell/myofibroblast-like cells as well as neutrophils in IPF. These data suggest that mast cell-derived bFGF might exert fibrogenic, proliferative effects on smooth muscle cell/myofibroblast-like cells through its receptors.

VEGF and bFGF are highly expressed in intraluminal fibromyxoid lesions in bronchiolitis obliterans organizing pneumonia

Bronchiolitis obliterans organizing pneumonia (BOOP) and usual interstitial pneumonia (UIP) are fibrous pulmonary disorders in which new fibromyxoid connective tissue is formed in distal air spaces. In BOOP this tissue is susceptible to even complete reversal, but in UIP it participates in the remodelling of the interstitium. Our previous study showed that in BOOP this newly formed intraluminal tissue is more capillarized than in UIP. This paper studies the immunohistochemical expression of vascular endothelial growth factor (VEGF) and its receptors Flt-1 and Flk-1, and basic fibroblast growth factor (bFGF) in BOOP and UIP. It was hypothesized that there would be a difference in the expression of these angiogenic growth factors paralleling the difference in their capillarization. The results show that both VEGF and bFGF are widely expressed in BOOP and in UIP. It was shown with two different VEGF antibodies that its expression was more pronounced in the intraluminal fibromyxoid lesions in BOOP than in UIP (p<0.001 and 0.004, respectively). Similarly, bFGF also showed stronger espression in BOOP than in UIP (p<0.02) in these areas. The expression of Flt-1 and Flk-1 was in agreement with the expression of VEGF. It is concluded that the growth factors VEGF and bFGF may have an important role in the pathogenesis of BOOP and UIP; furthermore, their expression correlates with the angiogenic activity of the newly formed intraluminal fibromyxoid connective tissue in BOOP. Angiogenesis mediated by these growth factors may be one reason for the reversal of intraluminal fibromyxoid connective tissue in BOOP and for its good clinical outcome.

Mast cell basic fibroblast growth factor in silicosis

To investigate the role of mast cells (MC) and their fibrogenic growth factors in silicosis, we performed quantitative immunohistochemistry for MC tryptase and for basic fibroblast growth factor (bFGF) in lung tissue from silicotic and control subjects. Anti-bFGF antibody was bound to lung MC, basement membrane, endothelial cells, and smooth-muscle cells. Morphometric analysis revealed that the volume density (V(v)) of MC was increased in silicotic lung and that the V(v) of bFGF-positive (bFGF(+)) cells was significantly higher than normal in silicotic lung. Most MC contained bFGF (rho = 0.88, p < 0.001). The V(v) of collagen/reticulin fibers was increased in silicosis and correlated with the V(v) of bFGF(+) cells (rho = 0.81, p < 0.001). Immature silicotic nodules contained bFGF(+) MC throughout the loose array of collagen/reticulin fibers. In large, mature nodules, the density of collagen/reticulin fibers was higher, and bFGF(+) MC were found only in the nodule periphery. Because of this circumferential MC alignment in silicotic nodules, we observed a negative correlation between the V(v) of bFGF(+) MC and the density of collagen/reticulin fibers in silicotic nodules (rho = -0.80, p < 0.001) and between the V(v) of all other nodule-associated cells and the density of collagen/reticulin fibers in the hypocellular nodule centers (rho = -0.84, p < 0.001). We conclude that MC that produce bFGF may play an important role in the development of silicosis.

Reversal of HO-1 related cytoprotection with increased expression is due to reactive iron

It is often postulated that the cytoprotective nature of heme oxygenase (HO-1) explains the inducible nature of this enzyme. However, the mechanisms by which protection occurs are not verified by systematic evaluation of the physiological effects of HO. To explain how induction of HO-1 results in protection against oxygen toxicity, hamster fibroblasts (HA-1) were stably transfected with a tetracycline response plasmid containing the full-length rat HO-1 cDNA construct to allow for regulation of gene expression by varying concentrations of doxycycline (Dox). Transfected cells were exposed to hyperoxia (95% O(2)/5% CO2) for 24 h and several markers of oxidative injury were measured. With varying concentrations of Dox, HO activity was regulated between 3- and 17-fold. Despite cytoprotection with low (less than fivefold) HO activity, high levels of HO-1 expression (greater than 15-fold) were associated with significant oxygen cytotoxicity. Levels of non-heme reactive iron correlated with cellular injury in hyperoxia whereas lower levels of heme were associated with cytoprotection. Cellular levels of cyclic GMP and bilirubin were not significantly altered by modification of HO activity, precluding a substantial role for activation of guanylate cyclase by carbon monoxide or for accumulation of bile pigments in the physiological consequences of HO-1 overexpression. Inhibition of HO activity or chelation of cellular iron prior to hyperoxic exposure decreased reactive iron levels in the samples and significantly reduced oxygen toxicity. We conclude that there is a beneficial threshold of HO-1 overexpression related to the accumulation of reactive iron released in the degradation of heme. Therefore, despite the ready induction of HO-1 in oxidant stress, accumulation of reactive iron formed makes it unlikely that exaggerated expression of HO-1 is a cytoprotective response.

Proliferation, C-myc, and cyclin D1 expression in diffuse alveolar damage: potential roles in pathogenesis and implications for prognosis

In this study we compared expression of DNA topoisomerase IIalpha, a marker of cellular proliferation, c-myc, and cyclin D1 in lung biopsy specimens showing diffuse alveolar damage (DAD) with control lung tissues. We subsequently correlated DNA topoisomerase IIalpha, c-myc, and cyclin D1 expression with survival. We hypothesized that poor outcome may correlate with a higher proliferation index, and that c-myc and cyclin D1 activation are potentially important regulators of both proliferation and apoptosis in DAD. Immnuohistochemical stains for c-myc, cyclin D1, and DNA topoisomerase IIalpha were performed on 10 cases of DAD (15 cases for DNA topoisomerase IIalpha) and 10 control lungs. A proliferation index for each case was calculated by dividing the number of nuclei expressing DNA topoisomerase IIalpha by the total number of nuclei counted. The percentages of alveolar pneumocytes and interstitial cells staining positively for c-myc and cyclin D1 were estimated. The average proliferation index (DNA topoisomerase IIalpha index) in DAD (0.16 +/- 0.06, n = 15) was significantly greater than in control lungs (0.00 +/- 0.01, n = 10) (P < .0001). The average proliferation index of patients with DAD who died of respiratory failure (0.18 +/- 0.05, n = 9) was significantly greater than the average proliferation index of patients whose respiratory disease resolved or stabilized (0.11 +/- 0.05, n = 5) (P < .03). Expression of c-myc in alveolar pneumocytes and interstitial cells was more intense and slightly more widespread in cases of DAD compared with control lungs. In 9 of 10 cases of DAD, cyclin D1 expression was present in up to 30% of alveolar pneumocytes and up to 10% of interstitial cells. No staining for cyclin D1 was present in control lungs. These results show that the proliferation index in DAD potentially correlates with patient survival. Furthermore, enhanced expression of c-myc and cyclin D1 may contribute to dysregulation of cellular proliferation and apoptosis observed in DAD.

Perspective article: transforming growth factor-beta: crossroad of glucocorticoid and bleomycin regulation of collagen synthesis in lung fibroblasts

Fibrosis is a consequence of injury which is characterized by accumulation of excess collagen and other extracellular matrix components, resulting in the destruction of normal tissue architecture and function. Transforming growth factor-beta, a potent wound healing agent, has also been shown to be an agent that can produce fibrosis because it is a potent stimulator of collagen synthesis. Both glucocorticoids and bleomycin have recently been shown to affect collagen synthesis in opposite directions, by utilizing a common pathway of involving transforming growth factor-beta activator protein binding to the transforming growth factor-beta element. This article presents a mechanistic overview of collagen synthesis regulation by glucocorticoids and bleomycin through the transforming growth factor-beta pathway.

Basic fibroblast growth factor and fibrosis in Hodgkin's disease

Hodgkin's disease (HD) is characterized by the presence of Hodgkin and Reed-Sternberg (H-RS) cells against a hyperplastic background of reactive cells such as lymphocytes, histiocytes, plasma cells, eosinophils, neutrophils and stromal cells. In addition, the HD nodular sclerosis (NS) subtype shows characteristic fibrous bundles, while the other subtypes do not. The fibrosis is considered to correlate with multiple cytokines and cytokine networks. Basic fibroblast growth factor (bFGF), one of the potent stimulators of fibroblasts, has also been linked to the fibroproliferative process. To investigate the relationship of fibrosis and bFGF, we thus performed both immunostaining, in situ hybridization (ISH) and reverse transcriptase-polymerase chain reaction (RT-PCR) on 25 cases of HD, which included 12 cases with NS subtype, 10 cases with mixed cellularity (MC), and 3 cases with lymphocyte predominance (LP). In NS, the expression of bFGF was stronger than that in LP and MC. In addition, the H-RS cells in NS frequently expressed bFGF. The stromal cells and histiocytes in the background expressed bFGF in NS. However, in MC and LP the number of bFGF-expressed H-RS cells was small, and the bFGF expression of background cells was rarely detected. However, the amount of bFGF varied in each case with HD NS. The above results support the possibilities that H-RS cells and background cells are a cellular source of bFGF and that the bFGF expression of those cells is also one of the influencing factors in the development of fibrosis in the HD NS subtype.

Mast cells and their mediators in cutaneous wound healing--active participants or innocent bystanders?

Mast cells are traditionally viewed as effector cells of immediate type hypersensitivity reactions. There is, however, a growing body of evidence that the cells might play an important role in the maintenance of tissue homeostasis and repair. We here present our own data and those from the literature elucidating the possible role of mast cells during wound healing. Studies on the fate of mast cells in scars of varying ages suggest that these cells degranulate during wounding, with a marked decrease of chymase-positive cells, although the total number of cells does not decrease, based on SCF-receptor staining. Mast cells contain a plethora of preformed mediators like heparin, histamine, tryptase, chymase, VEGF and TNF-alpha which, on release during the initial stages of wound healing, affect bleeding and subsequent coagulation and acute inflammation. Various additional vasoactive and chemotactic, rapidly generated mediators (C3a, C5a, LTB4, LTC4, PAF) will contribute to these processes, whereas mast cell-derived proinflammatory and growth promoting peptide mediators (VEGF, FGF-2, PDGF, TGF-beta, NGF, IL-4, IL-8) contribute to neoangiogenesis, fibrinogenesis or re-epithelization during the repair process. The increasing number of tryptase-positive mast cells in older scars suggest that these cells continue to be exposed to specific chemotactic, growth- and differentiation-promoting factors throughout the process of tissue remodelling. All these data indicate that mast cells contribute in a major way to wound healing. their role as potential initiators of or as contributors to this process, compared to other cell types, will however have to be further elucidated.

Expression of basic fibroblast growth factor in nasal polyps

Basic fibroblast growth factor (bFGF) is a polypeptide that is mitogenic for a wide variety of cell types. We used Northern blot analysis and immunohistochemistry to determine if bFGF is expressed in the nasal polyp tissue; bFGF messenger RNA was detectable in the polyps examined by Northern blot analysis. Strong immunostaining for bFGF was found in blood vessels and along the basement membrane of the epithelial cell layers. Basal epithelial cells and some infiltrating mononuclear cells also stained for bFGF. Proliferating cell nuclear antigen colocalized with bFGF to basal epithelial cells, endothelial cells, and areas of focal epithelial metaplasia. The polyp tissue was double-labeled with a mouse monoclonal antitryptase, a specific mast cell marker, and anti-bFGF. A significant number (65% +/- 19%) of the bFGF-positive mononuclear cells in the polyp tissues were positive for tryptase. These findings suggest that bFGF may contribute to the endothelial and epithelial proliferation in nasal polyp tissues and that mast cells are one source of this growth factor.

Collagenase and gelatinase activities in bronchoalveolar lavage fluids during bleomycin-induced lung injury

Basement membrane degradation can be indicative of tissue injury, but the process may also release matrix-bound cytokines to stimulate cell regeneration. To investigate this process, acute lung injury was induced in rats by intratracheal bleomycin and animals were killed from 3 days to 8 weeks later. The lungs were lavaged with saline to collect bronchoalveolar lavage (BAL) fluid and cell proliferation was assessed by pulse incorporation of tritiated thymidine. Bleomycin induced rapid inflammation with increased cell numbers and protein levels in BAL. Collagen degradation products were also increased in BAL fluid from 3 days to 4 weeks. Incubating samples of BAL fluid with radiolabelled collagens I and IV showed that high levels of activity, particularly for the degradation of type IV collagen, were present as early as 3 days post-bleomycin and persisted over the 8-week period. Zymograms demonstrated the highest level of gelatinase A (MMP-2) activity in BAL fluid in the first 2 weeks after bleomycin. Coincident with peak basement membrane degradative activity was the onset of a phase of epithelial cell proliferation, as measured by labelled nuclei in autoradiographs. The results show that enzymes capable of degrading the alveolar basement membrane are secreted early in the lung injury phase and that their presence in BAL fluid can be used as a measure of alveolar wall damage. It is possible that this enzyme action may release bound cytokines from the basement membrane, since maximal gelatinase activity correlates with alveolar epithelial cell proliferation.