Assessment of risks of pulmonary infection during 12 months following immunosuppressive treatment for active connective tissue diseases: a large-scale prospective cohort study

OBJECTIVE

Pulmonary infections (PI) are leading causes of death in patients with connective tissue diseases (CTD). The PREVENT study (Pulmonary infections in patients REceiving immunosuppressiVE treatmeNT for CTD) assessed risk of PI in patients with active CTD in the contemporary era of advanced immunosuppressive therapy.

METHODS

In patients who started corticosteroids (n = 763), conventional immunosuppressants or biologics for active CTD were enrolled. Clinical and laboratory data, usage of drugs, and occurrence of PI were collected for 12 months. Baseline risk factors were investigated using Cox regression analysis. A nested case-control (NCC) study was performed with 1:2 matched case-control pairs to assess the risk for each drug category.

RESULTS

During the observation period, 32 patients died (4.2%) and 66 patients were lost to followup (8.6%). Patients with PI (n = 61, 8%) had a significantly worse accumulated survival rate than patients without (p < 0.01). Cox hazard regression analysis using baseline data showed that these factors were significantly associated with PI: age ≥ 65 years (HR 3.87, 95% CI 2.22-6.74), ≥ 20 pack-years of smoking (2.63, 1.37-5.04), higher serum creatinine level (1.21, 1.05-1.41 per 1.0 mg/dl increase), and maximum prednisolone (PSL) dose during the first 2 weeks of treatment (2.81, 1.35-5.86 per 1.0 mg/kg/day increase). Logistic regression analysis by an NCC study revealed that maximum PSL dose within 14 days before PI (OR 4.82, 95% CI 1.36-17.01 per 1.0 mg/dl increase; 2.57, 1.28-5.16 if ≥ 0.5 mg/kg/day) was significantly associated with the events, while other immunosuppressants were not.

CONCLUSION

Physicians should be aware of the higher risks for corticosteroids of PI than other immunosuppressants and assess these risk factors before immunosuppressive treatment, to prevent PI.

Pulmonary infections following immunosuppressive treatments during hospitalization worsen the short-term vital prognosis for patients with connective tissue disease-associated interstitial pneumonia

OBJECTIVE

Connective tissue disease-associated interstitial pneumonia (CTD-IP) significantly affects the mortality of patients with CTD. The purpose of the present study is to identify causes and risk factors for death during hospitalization for immunosuppressive treatment of CTD-IP.

METHODS

A multicenter, retrospective study was conducted that collected data from patients with CTD who had been hospitalized for commencing or intensifying immunosuppressive treatment of CTD-IP using a standardized case report form. Risk factors were identified using the Cox proportional hazard regression model.

RESULTS

A total of 322 CTD-IP patients were enrolled with rheumatoid arthritis (n = 84), systemic lupus erythematosus (n = 13), polymyositis (n = 33), dermatomyositis (n = 69), systemic sclerosis (n = 55), mixed connective tissue disease (n = 21), microscopic polyangiitis (n = 19), and overlap syndrome (n = 28). Of the 42 patients who died during hospitalization, 22 died from CTD-IP, 15 from CTD-IP and pulmonary infection, 2 from pulmonary infection, and 3 from other causes. Age ≥ 65 years and development of pulmonary infections after commencing or intensifying immunosuppressive treatments were identified as risk factors for death during hospitalization after adjusting for covariates.

CONCLUSION

Careful consideration of the benefit-risk balance of immunosuppressive treatment for CTD-IP is indispensable for improving the short-term vital prognosis of these patients.

Perillyl alcohol suppresses antigen-induced immune responses in the lung

Perillyl alcohol (POH) is an isoprenoid which inhibits farnesyl transferase and geranylgeranyl transferase, key enzymes that induce conformational and functional changes in small G proteins to conduct signal production for cell proliferation. Thus, it has been tried for the treatment of cancers. However, although it affects the proliferation of immunocytes, its influence on immune responses has been examined in only a few studies. Notably, its effect on antigen-induced immune responses has not been studied. In this study, we examined whether POH suppresses Ag-induced immune responses with a mouse model of allergic airway inflammation. POH treatment of sensitized mice suppressed proliferation and cytokine production in Ag-stimulated spleen cells or CD4(+) T cells. Further, sensitized mice received aerosolized OVA to induce allergic airway inflammation, and some mice received POH treatment. POH significantly suppressed indicators of allergic airway inflammation such as airway eosinophilia. Cytokine production in thoracic lymph nodes was also significantly suppressed. These results demonstrate that POH suppresses antigen-induced immune responses in the lung. Considering that it exists naturally, POH could be a novel preventive or therapeutic option for immunologic lung disorders such as asthma with minimal side effects.

Suppression of experimental autoimmune encephalomyelitis by interleukin-10 transduced neural stem/progenitor cells

Neural stem/progenitor cells (NSPCs) have the ability to migrate into the central nervous system (CNS) to replace damaged cells. In inflammatory CNS disease, cytokine transduced neural stem cells may be used as vehicles to specifically reduce inflammation and promote cell replacement. In this study, we used NSPCs overexpressing IL-10, an immunomodulatory cytokine, in an animal model for CNS inflammation and multiple sclerosis (MS). Intravenous injection of IL-10 transduced neural stem/progenitor cells (NSPC^IL-10) suppressed myelin oligodendrocyte glycoprotein aa 35–55 (MOG35-55)- induced experimental autoimmune encephalomyelitis (EAE) and, following intravenous injection, NSPC^IL-10 migrated to peripheral lymphoid organs and into the CNS. NSPC^IL-10 suppressed antigen-specific proliferation and proinflammatory cytokine production of lymph node cells obtained from MOG35-55 peptide immunized mice. In this model, IL-10 producing NSPCs act via a peripheral immunosuppressive effect to attenuate EAE.

Alendronate attenuates eosinophilic airway inflammation associated with suppression of Th2 cytokines, Th17 cytokines, and eotaxin-2

Bisphosphonates (BPs) have been widely used to treat osteoporosis. They act by inhibiting farnesyl diphosphate synthase in the mevalonate pathway. This resembles the action of statins, whose immune-modulating effect has recently been highlighted. In contrast, the effect of BPs on immune responses has not been elucidated well. In this study, we examined the effect of alendronate (ALN), a nitrogen-containing BP, on allergic airway inflammation in a mouse model. BALB/c mice were sensitized twice with OVA and challenged three times with nebulized OVA to induce eosinophilic airway inflammation. ALN was administered by an intragastric tube before each inhalation. ALN strongly suppressed airway eosinophilia and Th2, as well as Th17 cytokine production in the lung. ALN also attenuated eotaxin-2 production in the lung. Immunohistochemistry demonstrated that the major cell source of eotaxin-2 was peribronchial/perivascular macrophages, and flow cytometrical studies confirmed that ALN decreased eotaxin-2 expression in these macrophages. Furthermore, ALN attenuated eotaxin-2 production from mouse pleural macrophages and human monocyte/macrophage-like THP-1 cells in vitro. These results suggest that ALN suppressed Ag-induced airway responses in the mouse model. The suppression of eotaxin-2 production from macrophages appears to be one of ALN's immunomodulatory effects, whereas the mechanism by which ALN suppressed Th2 and Th17 responses could not be fully elucidated in this study. Although a clinical study should be conducted, ALN could be a novel therapeutic option for asthma.

Elevation of KL-6 serum levels in clinical trials of tumor necrosis factor inhibitors in patients with rheumatoid arthritis: a report from the Japan College of Rheumatology Ad Hoc Committee for Safety of Biological DMARDs

OBJECTIVE

The associations between elevated levels of serum Krebs von den Lungen-6 (KL-6) and treatment of rheumatoid arthritis (RA) with tumor necrosis factor (TNF) inhibitors were investigated in five Japanese clinical trials.

METHODS

Percentages and incidence rates were calculated for elevated serum KL-6 levels. Adverse events associated with elevated levels of serum KL-6 were investigated.

RESULTS

In RISING, a clinical trial for infliximab, 15.6 % of the enrolled patients met criterion B (KL-6 ≥500 U/ml and >1.5-fold increase over the baseline value) by week 54. In HIKARI, 7.8 % of the certolizumab pegol (CZP) group and 0 % of the placebo group met criterion B during the double-blind (DB) period (p = 0.003). In J-RAPID, 8.4 % of the methotrexate (MTX) + CZP and 3.9 % of the MTX + placebo groups met criterion B during the DB period. In GO-MONO, 1.8 % of the golimumab (GLM) and 1.3 % of the placebo groups met criterion B during the DB period. In GO-FORTH, 7.1 % of the MTX + GLM and 0 % of the MTX + placebo groups met criteron B during the DB period (p = 0.017). No adverse events accompanied the elevation of serum KL-6 levels in 95.7 % of these patients.

CONCLUSION

Serum KL-6 levels may increase during anti-TNF therapy without significant clinical events. In these patients, continuing treatment with TNF inhibitors under careful observation is a reasonable option.

A retrospective study of serum KL-6 levels during treatment with biological disease-modifying antirheumatic drugs in rheumatoid arthritis patients: a report from the Ad Hoc Committee for Safety of Biological DMARDs of the Japan College of Rheumatology

OBJECTIVE

We investigated associations between treatment with methotrexate (MTX) or biological disease-modifying antirheumatic drugs (DMARDs) and elevation of serum Krebs von den Lungen-6 (KL-6) levels in Japanese patients with rheumatoid arthritis (RA).

METHODS

Using a standardized form, data were collected retrospectively from medical records and analyzed descriptively.

RESULTS

Of a total of 198 RA patients with KL-6 serum levels measured at initiation of treatment (month 0) and two or more times by month 12, 27 (17.9 %) of 151 RA patients treated with biological DMARDs, including infliximab, etanercept, adalimumab, and tocilizumab (the biological DMARDs group), and 5 (10.6 %) of 47 patients treated without biological DMARDs but with MTX (MTX group), met criterion B (max. KL-6 ≥500 U/ml and >1.5-fold from baseline) by 12 months. The majority of patients (n = 28) meeting criterion B had no apparent interstitial lung disease or malignancy. Of these 28 patients, 21 had serum KL-6 levels available after reaching their maximum level, and 13 (61.9 %) of the 21 then met criterion R [decrease to less than 500 U/ml or to less than (baseline + 0.5 × (maximum - baseline))] by month 12.

CONCLUSION

Serum KL-6 levels may increase during treatment with MTX or these biological DMARDs without significant clinical events.

cGMP-dependent protein kinase I is involved in neurite outgrowth via a Rho effector, rhotekin, in Neuro2A neuroblastoma cells

Although the cGMP/cGMP-dependent protein kinase (cGK) signaling is involved in the regulation of neurite outgrowth, its mechanism remains to be clarified. In this study, we identified a Rho effector, rhotekin, as a cGK-I-interacting protein. Rhotekin was also a substrate for cGK-Iα. In neurite-extended Neuro2A neuroblastoma cells, cGK-Iα and rhotekin were colocalized in the plasma membrane and extended neurites, while treatment with cGMP resulted in translocation of rhotekin to the cytoplasm. In addition, we found that cGK-Iα and rhotekin synergistically suppressed Rho-induced neurite retraction. Our findings suggest that cGK-Iα interacts with and phosphorylates rhotekin, thereby contributing to neurite outgrowth regulation.

High expression of IL-22 suppresses antigen-induced immune responses and eosinophilic airway inflammation via an IL-10-associated mechanism

Allergic inflammation in the airway is generally considered a Th2-type immune response. However, Th17-type immune responses also play important roles in this process, especially in the pathogenesis of severe asthma. IL-22 is a Th17-type cytokine and thus might play roles in the development of allergic airway inflammation. There is increasing evidence that IL-22 can act as a proinflammatory or anti-inflammatory cytokine depending on the inflammatory context. However, its role in Ag-induced immune responses is not well understood. This study examined whether IL-22 could suppress allergic airway inflammation and its mechanism of action. BALB/c mice were sensitized and challenged with OVA-Ag to induce airway inflammation. An IL-22-producing plasmid vector was delivered before the systemic sensitization or immediately before the airway challenge. Delivery of the IL-22 gene before sensitization, but not immediately before challenge, suppressed eosinophilic airway inflammation. IL-22 gene delivery suppressed Ag-induced proliferation and overall cytokine production in CD4(+) T cells, indicating that it could suppress Ag-induced T cell priming. Antagonism of IL-22 by IL-22-binding protein abolished IL-22-induced immune suppression, suggesting that IL-22 protein itself played an essential role. IL-22 gene delivery neither increased regulatory T cells nor suppressed dendritic cell functions. The suppression by IL-22 was abolished by deletion of the IL-10 gene or neutralization of the IL-10 protein. Finally, IL-22 gene delivery increased IL-10 production in draining lymph nodes. These findings suggested that IL-22 could have an immunosuppressive effect during the early stage of an immune response. Furthermore, IL-10 plays an important role in the immune suppression by IL-22.

Dopamine D1-like receptor antagonist attenuates Th17-mediated immune response and ovalbumin antigen-induced neutrophilic airway inflammation

Allergic airway inflammation is generally considered a Th2-type immune response. Recent studies, however, demonstrated that Th17-type immune responses also play important roles in this process, especially in the pathogenesis of neutrophilic airway inflammation, a hallmark of severe asthma. We previously reported that dendritic cells release dopamine to naive CD4(+) T cells in Ag-specific cell-cell interaction, in turn inducing Th17 differentiation through dopamine D1-like receptor (D1-like-R). D1-like-R antagonist attenuates Th17-mediated diseases such as experimental autoimmune encephalomyelitis and autoimmune diabetes. However, the effect of antagonizing D1-like-R on Th17-mediated airway inflammation has yet to be studied. In this study, we examined whether D1-like-R antagonist suppresses OVA-induced neutrophilic airway inflammation in OVA TCR-transgenic DO11.10 mice and then elucidated the mechanism of action. DO11.10 mice were nebulized with OVA or PBS, and some mice received D1-like-R antagonist orally before OVA nebulization. D1-like-R antagonist significantly suppressed OVA-induced neutrophilic airway inflammation in DO11.10 mice. It also inhibited the production of IL-17 and infiltration of Th17 cells in the lung. Further, D1-like-R antagonist suppressed the production of IL-23 by lung CD11c(+) APCs. In contrast, D1-like-R antagonist did not increase Foxp3(+) regulatory T cells in the lung. D1-like-R antagonist neither suppressed nonspecific LPS-induced neutrophilic airway inflammation nor OVA-induced eosinophilic airway inflammation. These results indicate that D1-like-R antagonist could suppress Th17-mediated neutrophilic airway inflammation, raising the possibility that antagonizing D1-like-R serves as a promising new strategy for treating neutrophil-dominant severe asthma.

Clinical and radiological features of acute-onset diffuse interstitial lung diseases in patients with rheumatoid arthritis receiving treatment with biological agents: importance of Pneumocystis pneumonia in Japan revealed by a multicenter study

OBJECTIVE

Acute-onset diffuse interstitial lung disease (AoDILD) in patients with rheumatoid arthritis (RA) has been a serious concern, especially for those under treatment with biological agents which may affect the presentation and outcome of AoDILD, including Pneumocystis pneumonia (PCP). Therefore, we conducted a retrospective, multi-center study of AoDILD in RA patients receiving biological agents.

METHODS

Patients who developed AoDILD while receiving biological agents (infliximab, etanercept, adalimumab and tocilizumab) were enrolled in the study. Definite PCP was defined as patients who showed either P. jirovecii organisms in their respiratory samples by microscopic examination, or positive tests for both P. jirovicii DNA-PCR with respiratory samples and an elevated serum 1,3-β-D-glucan level above the cut-off value. Probable PCP was defined as either a positive test for P. jirovicii PCR or an elevated serum β-D-glucan level. Chest HRCT findings were evaluated and scored by two board-certified radiologists.

RESULTS

The final diagnoses for 26 patients examined were definite PCP for 13 patients, probable PCP for 11, and methotrexate-associated pneumonitis in 2 patients. Definite and probable PCP cases were clinically indistinguishable. Generalized, diffuse ground-glass opacity (GGO) is the characteristic HRCT finding in patients with definite or probable PCP, which was different from our previous findings in RA patients, mostly without biologics, showing GGO distributed in a panlobular or multilobular manner. The clinical outcome was favorable by treatment with trimethoprim-sulfamethoxazole and glucocorticoids.

CONCLUSION

The possibility of PCP should be intensively investigated in RA patients developing AoDILD while receiving biological agents.

Intratracheal delivery of hepatocyte growth factor directly attenuates allergic airway inflammation in mice

Hepatocyte growth factor (HGF) has an important role in many biological events such as angiogenesis and cell proliferation, as well as anti-fibrotic and anti-apoptotic effects. In addition, we found that HGF suppresses antigen-induced immune responses in the airway by suppressing dendritic cell functions, using a HGF-producing plasmid vector. In the present study, we examined whether delivery of the HGF protein in the lung attenuates allergic airway inflammation in a mouse model. Generally, HGF is rapidly cleared from organs. So, to achieve the efficient delivery of HGF, we prepared a slow-releasing form by mounting recombinant human (rh) HGF protein in biodegradable gelatin hydrogels. BALB/c mice were immunized and then challenged with ovalbumin (OVA) to induce eosinophilic airway inflammation. Intratracheal delivery of a very small amount of gelatin-coupled rhHGF (0.3 microg) just once before the inhalation of OVA significantly suppressed eosinophilic airway inflammation. In addition, cytokine production in thoracic lymph nodes and the antigen-presenting capacity of lung CD11c+ cells were reduced. In contrast, delivery of 1.0 microg of rhHGF did not exhibit any significantly suppressive effect. These results suggest that the controlled release of rhHGF protein can suppress antigen-induced allergic immune responses in the lung. Therefore, HGF could be a novel therapeutic option for asthma.

Upregulation of lung dendritic cell functions in elastase-induced emphysema

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is now considered a chronic inflammatory disease. Although dendritic cells (DCs) are thought to play a key role in immune responses, studies investigating the role of DCs in COPD are quite limited.

METHODS

Porcine pancreas elastase was intratracheally administered to C57BL/6J mice on day 0. On days 2, 7 and 14, emphysema formation was evaluated by pressure-volume relationships and microscopic findings, including measurement of the mean linear intercept. Lung DCs were isolated on day 2, and their ability to stimulate allogeneic T cells and to produce cytokines was examined.

RESULTS

Pathologic emphysematous change was observed on day 2 and a significant increase in lung volume was observed on day 14. Lung DC function, such as the induction of T-cell proliferation and IL-10 production, was upregulated.

CONCLUSIONS

Upregulation of DC function was observed in elastase-induced emphysema. Further investigation on the contribution to emphysema formation may provide a useful target for future therapy.

Pravastatin attenuates allergic airway inflammation by suppressing antigen sensitisation, interleukin 17 production and antigen presentation in the lung

BACKGROUND

Statins are widely used to treat hyperlipidaemia. Their immunosuppressive effect has recently been confirmed in various immune mediated disease models. However, relatively few studies have been conducted on allergic inflammation, so the precise mechanisms of their actions against allergies have not been fully clarified. On the other hand, the role of interleukin (IL)17 in immune responses has been recently highlighted, but whether statins affect IL17 production has not been well studied. The effect of pravastatin on allergic airway inflammation in a mouse model was examined to elucidate the mechanism of action, focusing on its effect on IL17 production.

METHODS

BALB/c mice were immunised with ovalbumin (OVA) and then challenged with OVA aerosol. Pravastatin was delivered by intraperitoneal injection during either sensitisation or the challenge.

RESULTS

When delivered during systemic sensitisation, pravastatin suppressed OVA induced proliferation and production of Th2 type cytokines such as IL5 in spleen cells ex vivo and in vitro. IL17 production was also suppressed. Furthermore, pavastatin delivered during the inhalation of OVA attenuated eosinophilic airway inflammation, OVA specific IgE production in serum and OVA induced IL17 production in the thoracic lymph node. We also found that pravastatin attenuated the antigen presenting capacity of CD11c(+) cells obtained from the OVA challenged lung.

CONCLUSION

Pravastatin suppresses the systemic sensitisation to allergen with downregulation of IL17 production. It also suppresses an ongoing immune response in the airway partly by suppressing antigen presentation in the lung. Therefore, statins could be a novel therapeutic option for treatment of asthma.

Clinical and radiological features of Pneumocystis pneumonia in patients with rheumatoid arthritis, in comparison with methotrexate pneumonitis and Pneumocystis pneumonia in acquired immunodeficiency syndrome: a multicenter study

OBJECTIVE

To elucidate the clinical and radiological features of Pneumocystis pneumonia (PCP) in patients with rheumatoid arthritis (RA), compared with methotrexate (MTX) pneumonitis in RA and Pneumocystis pneumonia in acquired immunodeficiency syndrome (AIDS).

SUBJECTS AND METHODS

Retrospective analysis of 14 PCP cases in RA (RA-PCP), 10 MTX pneumonitis cases in RA (MTX-P) and 11 PCP cases in AIDS (AIDS-PCP) from 9 centers in the Kanto area in the last 6 years.

RESULTS

Compared with AIDS-PCP, both RA-PCP and MTX-P developed more rapidly, showing higher serum CRP and lower plasma beta-D-glucan levels, and more severe oxygenation impairment. In most of the RA-PCP cases, a high dose of corticosteroid was administered as adjunctive therapy, resulting in a favorable outcome. The mortality was 14% in RA-PCP, 0% in AIDS-PCP and 0% in MTX-P cases. In RA-PCP patients the CD4 cell count showed only mild suppression, not reaching the predisposing level for PCP in HIV infection, suggesting that there are risk factors for RA-PCP other than immunosuppression. Radiologic analysis revealed some characteristic patterns of each disease. In MTX-P, diffuse homogeneous ground glass opacity (GGO) with sharp demarcation by interlobular septa (type A GGO) was found in 70%, while in AIDS-PCP diffuse, homogeneous or nonhomogeneous GGO without interlobular septal boundaries (type B GGO) was predominant (91%). In RA-PCP, type A GGO was found in 6 cases and type B GGO in 5 cases, showing the complex nature of this disease.

CONCLUSION

RA-PCP differed considerably from AIDS-PCP clinically and radiologically. Clinically it occurred without severe immunosuppression, and showed characteristic aspects, with more intense inflammation and less parasite burden. Radiologically it mimicked MTX-P in some cases sharing the conspicuous CT features of MTX-P, rendering the distinction of these two disorders difficult.

Hepatocyte growth factor significantly suppresses collagen-induced arthritis in mice

Hepatocyte growth factor (HGF) plays an important role in angiogenesis, cell proliferation, antifibrosis, and antiapoptosis. Moreover, recent studies have highlighted the immunosuppressive effect of HGF in animal models of allogenic heart transplantation and autoimmune myocarditis and in studies in vitro as well. We also reported that HGF significantly suppresses dendritic cell function, thus down-regulating Ag-induced Th1-type and Th2-type immune responses in allergic airway inflammation. However, the immunosuppressive effect of HGF in many other situations has not been fully clarified. In the present study, using a mouse model of collagen-induced arthritis (CIA) and experiments in vitro, we examined the effect of HGF on autoimmune arthritis and then elucidated the mechanisms of action of HGF. To achieve sufficient delivery of HGF, we used biodegradable gelatin hydrogels as a carrier. HGF suppressed Ag-induced T cell priming by regulating the functions of dendritic cells in the Ag-sensitization phase with down-regulation of IL-10. In contrast, under continuous Ag stimulation HGF induced IL-10-producing immunocytes both in vivo and in vitro. Moreover, HGF potently inhibited the development of CIA with enhancing the Th2-type immune response. We also confirmed that HGF significantly suppressed the production of IL-17 by immunocytes. These results indicate that HGF suppresses the development of CIA through different ways at different phases. They also suggest that HGF could be an attractive tool for treating patients with rheumatoid arthritis.

IL-5-induced hypereosinophilia suppresses the antigen-induced immune response via a TGF-beta-dependent mechanism

Although eosinophils play an essential role in allergic inflammation, their role has recently been under controversy. Epidemic studies suggest that hypereosinophilia induced by parasite infection could suppress subsequent Ag sensitization, although the mechanism has not been fully clarified. In this study, we investigated whether eosinophils could suppress the Ag-specific immune response in the airway. BALB/c mice were sensitized and airway challenged with OVA. Systemic hypereosinophilia was induced by delivery of an IL-5-producing plasmid. IL-5 gene delivery suppressed the Ag-specific proliferation and cytokine production of CD4+ T cells in the spleen. IL-5 gene delivery before OVA sensitization significantly suppressed airway eosinophilia and hyperresponsiveness provoked by subsequent OVA airway challenge, while delivery during the OVA challenge did not suppress them. This IL-5-induced immune suppression was abolished in eosinophil-ablated mice, suggesting an essential role of eosinophils. IL-5 treatment increased the production of TGF-beta1 in the spleen, and we demonstrated that the main cellular source of TGF-beta1 production was eosinophils, using eosinophil-ablated mice and depletion study. TGF-beta1, but not IL-5 itself, suppressed the Ag-specific immune response of CD4+ T cells in vitro. Furthermore, IL-5 treatment enhanced phosphorylation of Smad2 in CD4+ T cells. Finally, a TGF-beta type I receptor kinase inhibitor restored this IL-5-induced immune suppression both in vitro and in vivo. These results suggest that IL-5-induced hypereosinophilia could suppress sensitization to Ag via a TGF-beta-dependent mechanism, thus suppressed allergic airway inflammation. Therefore, hypereosinophilia could reveal an immunosuppressive effect in the early stage of Ag-induced immune response.

Prolonged allergen challenge in murine nasal allergic rhinitis: nasal airway remodeling and adaptation of nasal airway responsiveness

BACKGROUND

Nasal airway remodeling exists in allergic rhinitis, but it appears to be far less extensive than in asthma. However, there has been little study about nasal airway remodeling and no study using mice models. It has been reported that airway hyperresponsiveness decreased after prolonged allergen challenge in a chronic murine asthma model together with the progression of remodeling. However, there has been no study of the relation of remodeling and airway responsiveness in nasal allergy. Therefore, we have undertaken this investigation to characterize nasal airway structural changes after prolonged allergen challenge and to examine the relationship between nasal airway hyperresponsivity and remodeling.

METHODS

We prepared murine allergic rhinitis for ovalbumin. Mice were subsequently challenged three times a week with ovalbumin from day 19 to days 53, 88, and 130. We examined allergen-induced nasal symptoms and objective nasal hyperresponsiveness using the enhanced pause system. Moreover, the pathologic changes were investigated after allergen challenge.

RESULTS

The extended allergen challenge protocol caused significant nasal airway remodeling. Specifically, remodeling was characterized by goblet cell hyperplasia and deposition of collagen in the submucosal area. Allergen-induced nasal hyperresponsiveness was first increased but gradually decreased in nasal symptoms and Penh after prolonged allergen challenge.

CONCLUSIONS

We have demonstrated that a remodeling of nasal mucosa in a murine allergic rhinitis model prolonged allergen exposure. Moreover, prolonged allergen exposure induced a reduction of nasal hyperresponsiveness together with a progression of nasal remodeling.

Noninvasive system for evaluating allergen-induced nasal hypersensitivity in murine allergic rhinitis

Until now there has been no method for physiologically evaluating nasal hypersensitivity in mice. Enhanced pause (Penh) has been used as an indicator that reflects changes in the lower airway. Recently, however, there is disagreement regarding the significance of the Penh system; this is because Penh is not essentially a physiological parameter, and it might not necessarily represent a change in the lower respiratory tract. The purpose of the present study is to investigate whether Penh could be applicable for analyzing nasal hypersensitivity in mice. BALB/c mice were sensitized with ovalbumin (OVA) through a combination of intraperitoneal injection and daily intranasal challenge in an awake condition. Penh was measured at each time point during sensitization, or a serial change in Penh value was followed after the final nasal challenge and the effect of treatment was assessed. Following sensitization and nasal challenge, the Penh value gradually increased and showed a significant difference on day 14. Changes in IgE, eosinophil infiltration into nasal mucosa, and OVA-induced symptoms all strongly correlated with the increase in Penh. On day 19, after OVA nasal provocation, Penh gradually increased and reached maximal values 25 min after the challenge. Pretreatment with dexamethasone or a histamine H1 blocker significantly suppressed this increase in Penh. We confirmed that intranasal OVA challenge did not induce bronchoconstriction by measuring airway resistance and bronchoalveolar lavage fluid, and through histological examination. These results clearly demonstrate that Penh could be a useful noninvasive indicator for studying nasal hypersensitivity.

In vivo IL-10 gene delivery attenuates bleomycin induced pulmonary fibrosis by inhibiting the production and activation of TGF-beta in the lung

BACKGROUND

Idiopathic pulmonary fibrosis is a devastating disorder for which there is no effective treatment. Transforming growth factor (TGF)-beta plays a critical role in provoking fibrosis. Interleukin (IL)-10 is a potent immunosuppressive cytokine but its effect on the fibrosing process is unclear. A study was undertaken to examine whether IL-10 affects the production and activation of TGF-beta and thus can attenuate the fibrosis.

METHODS

Mice were given an intratracheal injection of bleomycin. On day 1 or 14, IL-10 gene was delivered by rapid intravenous injection of Ringer's solution containing plasmid. Two weeks after the plasmid injection the mice were examined for fibrosis. The effect of IL-10 on TGF-beta production by alveolar macrophages was assessed.

RESULTS

Even when delivered during the fibrosing phase, IL-10 gene significantly suppressed the pathological findings, hydroxyproline content, and production of both active and total forms of TGF-beta1 in the lung. Immunohistochemical analyses showed that alveolar macrophages were one of the major sources of TGF-beta1 and IL-10 diminished the intensity of the staining. IL-10 also suppressed the expression of alphaV beta6 integrin, a molecule that plays an important role in TGF-beta activation, on lung epithelial cells. Alveolar macrophages from bleomycin injected mice produced TGF-beta1 spontaneously ex vivo, which was significantly suppressed by treatment of the mice in vivo or by treatment of the explanted macrophages ex vivo with IL-10.

CONCLUSION

IL-10 suppresses the production and activation of TGF-beta in the lung and thus attenuates pulmonary fibrosis, even when delivered in the chronic phase.

Splenic dendritic cells induced by oral antigen administration are important for the transfer of oral tolerance in an experimental model of asthma

Peripheral tolerance can be induced after the feeding of Ag, which is referred to as oral tolerance. We demonstrated in this study that the oral administration of OVA induced tolerance in an experimental model of asthma in mice, and investigated which cells function as the regulatory cells in the transfer of this oral tolerance. In OVA-fed mice, the percentage of eosinophils in bronchoalveolar lavage fluid, serum IgE levels, airway hyperresponsiveness, and mRNA levels of IL-13 and eotaxin were significantly lower than found in nonfed mice. Histological examination of lung tissue showed a suppression of the accumulation of inflammatory cells in the peribronchial area of OVA-fed mice. Feeding after the first immunization or between the first and the second immunization suppressed these findings, whereas feeding just before the airway Ag challenge did not. The suppression of disease in OVA-fed mice was successfully transferred by injection of whole spleen cells of OVA-fed mice. When CD11c+ dendritic cells (DCs) were removed from splenocytes, this transfer of suppression was completely abolished. The injection of splenic DCs purified from OVA-fed mice alone transferred the suppression, whereas the injection of splenic DCs from naive mice that were cocultured with OVA in vitro did not. These data suggest that not only CD4+ T cells, but also CD11c+ DCs induced by Ag feeding are important for the active transfer of oral tolerance in this murine experimental model of asthma.

A novel role of hepatocyte growth factor as an immune regulator through suppressing dendritic cell function

Hepatocyte growth factor (HGF) plays an important role in many biological events such as angiogenesis, cell proliferation, anti-fibrosis and antiapoptosis. It is well known that HGF promotes tumor progression and suppresses development of fibrosis after tissue injury. In contrast, its role in immune-mediated disorders has not been fully clarified. In the present study, we examined the role of HGF in Ag-specific immune response using in vitro studies and an experimental model of allergic airway inflammation. We first confirmed that dendritic cells (DCs) expressed the receptor for HGF, c-met, which was not expressed in T cells. Treatment with HGF both in vitro and in vivo potently suppressed DC functions such as Ag-presenting capacity, thus down-regulating Ag-induced Th1- and Th2-type immune responses. Exogenous administration of the HGF expression plasmid into Ag-primed mice markedly suppressed the development of airway eosinophilia and airway hyperresponsiveness, which was induced by Ag inhalation, with suppression of the Ag-presenting capacity of DCs in the lung. HGF exhibited these immunosuppressive effects without up-regulation of IL-10 or TGF-beta. We also found that expression of endogenous HGF in the lung significantly increased following Ag sensitization and inhalation challenges. Finally, neutralization of endogenous HGF in vivo significantly increased airway eosinophilia and airway hyperresponsiveness with up-regulation of the Ag-presenting capacity of DCs in the lung. These results demonstrated a novel, significant, and possibly therapeutic role of HGF as a potent regulator in immune-mediated disorders such as asthma.

Development of mushrooms for thrombosis prevention by protoplast fusion

With thrombosis a major cause of death in Japan and the Western world, thrombin-inhibitory agents that constrain the formation of fibrin are sought. We screened for basidiomycetes showing anti-thrombin activity and isolated Laetiporus sulphureus. However, it was difficult to cultivate and its form was not satisfactory. We therefore used protoplast fusion between L. sulphureus and the commonly cultivated basidiomycete Hypsizygus marmoreaus to obtain cultivable basidiomycetes that produced an anti-thrombin substance. For the protoplast fusion of L. sulphureus and H. marmoreaus, the protoplast concentration, alternating electric field intensity, dielectrophoresis duration, and field pulse intensity used were of 1 x 10(7) protoplasts/ml, 100 V/cm.1 MHz, 60 s, and 8 kV/cm, respectively. The number of regenerated colonies obtained was 4961, from which 43 strains were selected for electrophoretic analysis. Four of the fusants were found to have a band from each parent in isozyme patterns obtained using their crude extract. The fruiting bodies of the fusants were very similar to those of H. marmoreaus. Crude extract from each of the fusants and from L. sulphureus showed anti-coagulative activity in terms of the thrombin clotting time. We thus obtained improved basidiomycetes that produce an anti-thrombin substance, are easily cultivated, and whose form resembles H. marmoreaus, a commonly used culinary mushroom.

Antigen-sensitized CD4+CD62Llow memory/effector T helper 2 cells can induce airway hyperresponsiveness in an antigen free setting

Background

Airway hyperresponsiveness (AHR) is one of the most prominent features of asthma, however, precise mechanisms for its induction have not been fully elucidated. We previously reported that systemic antigen sensitization alone directly induces AHR before development of eosinophilic airway inflammation in a mouse model of allergic airway inflammation, which suggests a critical role of antigen-specific systemic immune response itself in the induction of AHR. In the present study, we examined this possibility by cell transfer experiment, and then analyzed which cell source was essential for this process.

Methods

BALB/c mice were immunized with ovalbumin (OVA) twice. Spleen cells were obtained from the mice and were transferred in naive mice. Four days later, AHR was assessed. We carried out bronchoalveolar lavage (BAL) to analyze inflammation and cytokine production in the lung. Fluorescence and immunohistochemical studies were performed to identify T cells recruiting and proliferating in the lung or in the gut of the recipient. To determine the essential phenotype, spleen cells were column purified by antibody-coated microbeads with negative or positive selection, and transferred. Then, AHR was assessed.

Results

Transfer of spleen cells obtained from OVA-sensitized mice induced a moderate, but significant, AHR without airway antigen challenge in naive mice without airway eosinophilia. Immunization with T helper (Th) 1 elicited antigen (OVA with complete Freund's adjuvant) did not induce the AHR. Transferred cells distributed among organs, and the cells proliferated in an antigen free setting for at least three days in the lung. This transfer-induced AHR persisted for one week. Interleukin-4 and 5 in the BAL fluid increased in the transferred mice. Immunoglobulin E was not involved in this transfer-induced AHR. Transfer of in vitro polarized CD4⁺ Th2 cells, but not Th1 cells, induced AHR. We finally clarified that CD4⁺CD62L^low memory/effector T cells recruited in the lung and proliferated, thus induced AHR.

Conclusion

These results suggest that antigen-sensitized memory/effector Th2 cells themselves play an important role for induction of basal AHR in an antigen free, eosinophil-independent setting. Therefore, regulation of CD4⁺ T cell-mediated immune response itself could be a critical therapeutic target for allergic asthma.

In Vivo IL-10 Gene Delivery Suppresses Airway Eosinophilia and Hyperreactivity by Down-Regulating APC Functions and Migration without Impairing the Antigen-Specific Systemic Immune Response in a Mouse Model of Allergic Airway Inflammation

IL-10 is an immunosuppressive cytokine. Although previous studies have reported that exogenous delivery of IL-10 reduced airway inflammation in experimental allergic airway inflammation, the mechanism of action has not been fully clarified. In this report, we elucidated a mechanism of action of IL-10 in vivo. BALB/c mice were immunized and aerosol challenged with OVA-Ag. We delivered the IL-10 gene to the mice before systemic sensitization or during aerosol Ag challenge by administering an IL-10-producing plasmid vector. Not only presensitization delivery of IL-10, as reported, but also delivery during inflammation strongly suppressed the development of airway eosinophilia and hyperreactivity. Presensitization delivery suppressed the Ag-specific Th2-type immune response in both the lung and spleen. In contrast, delivery in the effector phase suppressed the Th2 response only in the lung, whereas that in the spleen was not affected. IL-10 gene delivery did not induce the development of a regulatory phenotype of T cells or dendritic cells; rather, it suppressed the overall functions of CD11c(+) APCs of the lung such as Ag-presenting capacity, cytokine production, and transportation of OVA-Ag to lymph nodes, thus attenuating Th2-mediated allergic airway inflammation. Further, IL-10 revealed a distinct immunosuppressive effect in the presence of Ag and APCs. These results suggest that suppression of APC function in the lung, the site of immune response, played a critical role in the IL-10-mediated suppression of Ag-induced airway inflammation and hyperreactivity. Therefore, if delivered selectively, IL-10 could site specifically suppress the Ag-specific immune response without affecting systemic immune responses.

A Novel Role of Cysteinyl Leukotrienes to Promote Dendritic Cell Activation in the Antigen-Induced Immune Responses in the Lung

Although the critical role of cysteinyl leukotrienes (cysLTs) in the inflammation, especially eosinophilic lung inflammation, in asthma has been well documented, their role in the early stage of Ag-specific immune response has not been completely clarified. In the present study, with a mouse model of asthma and in vitro studies we demonstrated that cysLTs potentiated dendritic cell (DC) functions such as Ag-presenting capacity and cytokine production. The cysLT-1 receptor antagonist (LTRA) strongly suppressed the activation of these DC functions and led to inhibition of subsequent not only Th2, but also Th1, responses in the early stage of immune response. Moreover, treatment with LTRA during the early stage of the immune response potently suppressed the development of Ag inhalation-induced eosinophilic airway inflammation, mucus production, and airway hyper-reactivity in vivo. Treatment with LTRA significantly increased PGE(2) production in the lung, and treatment with the cyclooxygenase inhibitor indomethacin abolished LTRA's suppressive effect on DCs and deteriorated the Th2 and Th1 responses and airway inflammation. With in vitro studies, we also confirmed that cysLTs production by DCs increased with LPS stimulation, and that LTRA directly suppressed the alloantigen-presenting capacity of DCs. These results suggested that cysLTs potentiate DC functions both in vivo and in vitro, and that LTRA could be beneficial to suppress the initial immune response in many immune-mediated disorders beyond asthma.

[A case of eosinophilic lung disease presenting asthma-like symptoms and centrilobular shadows in both lung fields]

This case, in a 23-year-old man presenting with cough, sputum, dyspnea on effort and wheezing, had been diagnosed as bronchial asthma at another hospital. Because inhaled steroid and theophylline were far from effective, he was admitted to our hospital for further evaluation. A blood test revealed marked eosinophilia. Chest radiography showed diffuse, small nodular shadows in both lung fields, and a chest CT scan demonstrated diffuse centrilobular nodules and thickening of the bronchi and bronchioles. A spirometric test showed obstructive and restrictive ventilatory impairment, but the depressed forced vital capacity failed to show improvement in response to bronchodilator inhalation, discouraging a diagnosis of asthma. Eosinophilic lung disease with prominent eosinophilic bronchiolitis was diagnosed on the basis of BAL eosinophilia and thoracoscopic lung biopsy findings. The symptoms and blood eosinophilia were responsive to administration of oral prednisolone (30 mg daily); radiographic and CT findings also showed improvement. This case showed a marked similarity to the recently reported "eosinophilic bronchiolitis", and was probably not a type of bronchial asthma.

[Acute exacerbation of interstitial pneumonia associated with active systemic lupus erythematosus in a patient with rheumatoid arthritis]

A 36-year-old woman with rheumatoid arthritis was admitted to our hospital for evaluation of newly developed active systemic lupus erythematosus (SLE). After hospitalization, she showed progressive respiratory failure. Chest CT revealed exacerbation of interstitial pneumonia, showing acute development of air-space consolidation and ground-glass opacity in addition to intensified reticular shadows. Administration of high-dose corticosteroids and cyclosporine A resulted in recovery from respiratory failure, accompanied by obvious improvement in the chest radiographs and CT, as demonstrated by the disappearance of air-space consolidation and ground-glass opacity. Clinically, the exacerbation of her interstitial pneumonia was compatible with acute lupus pneumonitis, a rare complication with active SLE.

A two-way interaction between hepatocyte growth factor and interleukin-6 in tissue invasion of lung cancer cell line

Although both hepatocyte growth factor (HGF) and interleukin (IL)-6 play important roles in invasion of cancer cells, interaction between these two critical factors has not been well elucidated. In the present study we demonstrated a two-way interaction between HGF and IL-6 in in vitro invasion of a lung cancer cell line. A549 lung adenocarcinoma cells were stimulated with IL-6, and this treatment induced an upregulation of c-Met/HGF receptor mRNA expression in the cells. In addition, IL-6 enhanced the HGF-induced in vitro cell invasion. This effect was abolished by pretreatment of the cells with either anti-IL-6 neutralizing antibody or with anti-c-Met/HGF receptor blocking antibody. We also found that HGF upregulated the expression of IL-6 receptor mRNA in the same cell line, and that this upregulation enhanced the IL-6-induced cell invasion. Finally, costimulation with HGF and IL-6 showed an additive effect on invasion, and this effect was mediated by production of matrix metalloproteinase (MMP)-2 and MMP-9. These results suggest that HGF and IL-6 upregulate each other's receptors, and thus would cooperatively enhance tissue invasion. They also suggest an "autocrine circuit" among cytokines and growth factors in certain cancer cells which functions to accelerate their biologic activities such as metastatic property.

Interferon-gamma inhibits hepatocyte growth factor-stimulated cell proliferation of human bronchial epithelial cells: upregulation of p27(kip1) cyclin-dependent kinase inhibitor

Proliferation of bronchial epithelial cells is an important biologic process in a variety of physiologic and pathologic conditions. In this study, we demonstrate that hepatocyte growth factor (HGF) stimulates proliferation of human bronchial epithelial cells obtained from healthy volunteers. The mitogenic effect of HGF is dependent on costimulation with serum and is completely abrogated by interferon-gamma (IFN-gamma). In the absence of serum, HGF is capable of inducing activation of extracellular signal-regulated kinases (ERK)1 and ERK2, but fails to stimulate proliferation by itself. These effects of HGF and IFN-gamma were reproduced faithfully in BEAS-2B cells, which are an immortalized cell line derived from human bronchial epithelial cells. Further, we investigated the molecular mechanisms underlying the effects of HGF and IFN-gamma in BEAS-2B cells and found that the MEK1 inhibitor PD98059, but not the p38 M-associated protein kinase inhibitor SB203580, abrogates HGF-induced ERK activation and proliferation in response to HGF and serum. In addition, LY294002, which is the specific inhibitor of phosphatidyl inositol 3-kinase, partially inhibited HGF- and serum-stimulated proliferation. We also found that HGF by itself is capable of inducing a G1 cyclin, cyclin D1, but fails to downregulate p27(kip1) cyclin-dependent kinase (CDK) inhibitor, which is a requisite for G1 to S phase cell cycle progression. IFN-gamma does not interfere with the effects of HGF on either ERK activation or cyclin D1 induction; however, it prevents the downregulation of p27(kip1) CDK inhibitor that takes place in response to a combination of HGF and serum. These results indicate that the MEK-ERK signaling pathway is necessary but not sufficient for human bronchial epithelial cell proliferation, and implicate the significance of HGF and IFN-gamma in the repair processes of injured human bronchial epithelial cells.

Initial experience of percutaneous renal cryosurgery under the guidance of a horizontal open MRI system

OBJECTIVE

The aim of this study was to obtain preliminary results of cryoablation of renal tumors by using a percutaneous approach guided by a horizontal open MRI system, and to assess the safety and efficacy of this procedure.

MATERIALS AND METHODS

Four patients with renal tumors underwent percutaneous cryosurgery with local anesthesia using a horizontal open MRI system (AIRIS II, Hitachi Medical Corp., Tokyo, Japan). The size of the mass was radiographically documented as 4 cm or less in diameter. A 2- or 3-mm cryoprobe was advanced into the renal mass under real-time MR monitoring. Growth of the iceball during cryoablation was monitored by two-dimensional MR images. Follow-up dynamic CT and physical examination were done after two weeks and six weeks.

RESULT

MR imaging demonstrated the iceballs as sharply marginated regions of signal loss that expanded and engulfed the renal mass with clear contrast between the iceball and surrounding tissue. Cryoablated tumors resolved, and there were no serious complications and no clinically significant changes during the procedures and follow-up study.

CONCLUSION

In this limited clinical trial of percutaneous renal tumor surgery, cryoablation demonstrated its feasibility with minimal morbidity. Intraprocedual MR-guided cryosurgery can be used as a safe modality, although further studies are necessary to determine the long-term efficacy of this procedure.

Early interleukin 4-dependent response can induce airway hyperreactivity before development of airway inflammation in a mouse model of asthma

In experimental models of bronchial asthma with mice, airway inflammation and increase in airway hyperreactivity (AHR) are induced by a combination of systemic sensitization and airway challenge with allergens. In this report, we present another possibility: that systemic antigen-specific sensitization alone can induce AHR before the development of inflammation in the airway. Male BALB/c mice were sensitized with ovalbumin (OVA) by a combination of intraperitoneal injection and aerosol inhalation, and various parameters for airway inflammation and hyperreactivity were sequentially analyzed. Bronchial response measured by a noninvasive method (enhanced pause) and the eosinophil count and interleukin (IL)-5 concentration in bronchoalveolar lavage fluid (BALF) gradually increased following the sensitization, and significant increase was achieved after repeated OVA aerosol inhalation along with development of histologic changes of the airway. In contrast, AHR was already significantly increased by systemic sensitization alone, although airway inflammation hardly developed at that time point. BALF IL-4 concentration and the expression of IL-4 mRNA in the lung reached maximal values after the systemic sensitization, then subsequently decreased. Treatment of mice with anti-IL-4 neutralizing antibody during systemic sensitization significantly suppressed this early increase in AHR. In addition, IL-4 gene-targeted mice did not reveal this early increase in AHR by systemic sensitization. These results suggest that an immune response in the lung in an early stage of sensitization can induce airway hyperreactivity before development of an eosinophilic airway inflammation in BALB/c mice and that IL-4 plays an essential role in this process. If this early increase in AHR does occur in sensitized human infants, it could be another therapeutic target for early prevention of the future onset of asthma.

CT-guided percutaneous laser disk decompression (PLDD) for cervical disk hernia

OBJECTIVE

Percutaneous laser disk decompression (PLDD) is an effective treatment for bulging or protruding disk. The aim of this study was to present a method of PLDD for cervical disk hernia under CT guidance and to evaluate the efficacy and safety of this procedure.

MATERIALS AND METHODS

Seven patients with radiculalgia caused by cervical disk hernia were treated overnight by PLDD. A laser fiber was inserted through an 18 G needle into the target disk under CT guidance. A Nd-Yag laser (1,064 nm) was used for ablation. A CT scan was obtained every 60 joule (J) at the slice of the target disk to visualize the vaporized area during the procedure. The Japan Orthopedic Association (JOA) score of cervical radiculopathy (full score 15) and MacNab criteria were used for assessment of treatment response.

RESULTS

Puncture of the needle to the target disk was safely performed under CT guidance. The total dosage of laser ablation ranged from 120 to 500 J (average, 266 J). The overall success rate according to MacNab criteria was good in all cases. No complications were observed in our series.

CONCLUSION

The CT-guided technique provides safe, accurate PLDD for cervical disk hernia. PLDD for cervical disk hernia shows promise in the management of radiculalgia.

Hepatocyte growth factor attenuates collagen accumulation in a murine model of pulmonary fibrosis

We investigated the in vivo effects of recombinant human hepatocyte growth factor (HGF) on epithelial cell proliferation in normal mouse lung and on the repair process that follows bleomycin-induced lung injury. Intratracheal administration of 100 micrograms of rhHGF to C57BL/6 mice led to proliferation of bronchial and alveolar epithelial cells as indicated by an increased number of cells staining for proliferating cell nuclear antigen (PCNA). The effect of HGF on the lung repair process was examined by administration of 100 micrograms of rhHGF on Day 3 and Day 6 after intratracheal injection of bleomycin to mice. We found that HGF significantly attenuated collagen accumulation induced by bleomycin as determined by quantitation of hydroxyproline content and by scoring of the extent of fibrosis. To explore the potential mechanisms involved in the beneficial effects of HGF, we performed in vitro studies with A549 pulmonary epithelial cells and found that HGF enhanced cell surface plasmin generation, expression of u-PA activity, and cell migration. In summary, HGF has potent in vivo and in vitro effects on epithelial cells, which suggests it may have a role in the therapy of pulmonary fibrosis.