Risk factors for emphysema. Cigarette smoking is associated with a reduction in the association rate constant of lung alpha 1-antitrypsin for neutrophil elastase.

The increased risk of developing emphysema among individuals who smoke cigarettes and who have normal levels of alpha 1-antitrypsin (alpha 1AT) is hypothesized to result from a decrease in the antineutrophil elastase capacity of the lower respiratory tract alpha 1AT of smokers compared with nonsmokers. To evaluate this hypothesis we compared the time-dependent kinetics of the inhibition of neutrophil elastase by lung alpha 1AT from healthy, young cigarette smokers (n = 8) and nonsmokers (n = 12). alpha 1-antitrypsin was purified from lavage fluid using affinity and molecular sieve chromatography, and the association rate constant (k assoc) for neutrophil elastase quantified. The k assoc of smoker plasma alpha 1AT (9.5 +/- 0.5 X 10(6) M-1s-1) was similar to that of nonsmoker plasma (9.3 +/- 0.7 X 10(6) M-1s-1, P greater than 0.5). In marked contrast, the k assoc of smoker lower respiratory tract alpha 1AT was significantly lower than that of nonsmoker alpha 1AT (6.5 +/- 0.4 X 10(6) M-1s-1 vs. 8.1 +/- 0.5 X 10(6) M-1s-1, P less than 0.01). Furthermore, the smoker lower respiratory tract alpha 1AT k assoc was significantly less than that of autologous plasma (P less than 0.01). When considered in the context of the concentration of alpha 1AT in the lower respiratory tract epithelial lining fluid, the inhibition time for neutrophil elastase of smoker lung alpha 1AT was twofold greater than that of nonsmoker lung alpha 1AT (smoker: 0.34 +/- 0.05 s vs. nonsmoker: 0.17 +/- 0.05 s, P less than 0.01). Consequently, for concentrations of alpha 1AT in the lower respiratory tract it takes twice as long for an equivalent amount of neutrophil elastase to be inhibited in the smoker's lung compared with the nonsmoker's lung. These observations support the concept that cigarette smoking is associated with a decrease in the lower respiratory tract neutrophil elastase inhibitory capacity, thus increasing the vulnerability of the lung to elastolytic destruction and thereby increasing the risk for the development of emphysema.

Oxidants spontaneously released by alveolar macrophages of cigarette smokers can inactivate the active site of alpha 1-antitrypsin, rendering it ineffective as an inhibitor of neutrophil elastase.

Current concepts relating to the pathogenesis of emphysema associated with cigarette smoking is that an imbalance exists within the lower respiratory tract between neutrophil elastase and the local anti-neutrophil elastase screen, enabling uninhibited neutrophil elastase to destroy the alveolar structures over time. The possible role of alveolar macrophages in contributing to this imbalance was investigated by evaluating the ability of cigarette smokers' alveolar macrophages to inactivate alpha 1-antitrypsin (alpha 1AT), the major anti-neutrophil elastase of the human lower respiratory tract. In vitro, alveolar macrophages of smokers spontaneously released 2.5-fold more superoxide anion and eightfold more H2O2 than macrophages of nonsmokers (P less than 0.01, both comparisons). Using a model system that reproduced the relative amounts of alveolar macrophages and alpha 1AT found in the epithelial lining fluid of the lower respiratory tract, we observed that smokers' macrophages caused a 60 +/- 5% reduction in the ability of alpha 1AT to inhibit neutrophil elastase. In marked contrast, under the same conditions, nonsmokers' macrophages had no effect upon the anti-neutrophil elastase function of alpha 1AT. Addition of superoxide dismutase, catalase, mannitol, and methionine prevented inactivation of alpha 1AT by smokers' macrophages, implying that the release of oxidants mediated the inactivation of alpha 1AT. In addition, by utilizing a recombinant DNA produced modified form of alpha 1AT containing an active site substitution (met358----val), the inactivation of alpha 1AT by smokers' alveolar macrophages was prevented, suggesting that the smokers' macrophages inactivate alpha 1AT by oxidizing the active site of the alpha 1AT molecule. These results suggest that in cigarette smokers, the alveolar macrophage can modulate the activity of alpha 1AT as an inhibitor of neutrophil elastase and thus play a role in the pathogenesis of emphysema associated with cigarette smoking.

Z-type alpha 1-antitrypsin is less competent than M1-type alpha 1-antitrypsin as an inhibitor of neutrophil elastase.

Alpha 1-antitrypsin (alpha 1AT) deficiency resulting from homozygous inheritance of the Z-type alpha 1AT gene is associated with serum alpha 1AT levels of less than 50 mg/dl and the development of emphysema in the third to fourth decades. Despite the overwhelming evidence that the emphysema of PiZZ individuals develops because of a "deficiency" of alpha 1AT and hence an insufficient antineutrophil elastase defense of the lung, epidemiologic evidence has shown that levels of alpha 1AT of only 80 mg/dl protect the lung from an increased risk of emphysema. With this background, we hypothesized that homozygous inheritance of the Z-type may confer an added risk beyond a simple deficiency of alpha 1AT by virtue of an inability of the Z-type alpha 1AT molecule to inhibit neutrophil elastase as effectively as the common M1-type molecule. To evaluate this hypothesis, the functional status of alpha 1AT from PiZZ individuals (n = 10) was compared with that of alpha 1AT from PiM1M1 individuals (n = 7) for its ability to inhibit neutrophil elastase (percent inhibition) as well as its association rate constant for neutrophil elastase (K association). Plasma alpha 1AT concentration, measured by radial immunodiffusion, was 34 +/- 1 mg/dl in PiZZ patients vs. 237 +/- 14 mg/dl for PiM1M1 plasma, a sevenfold difference. When titrated against neutrophil elastase, the present inhibition of PiZZ plasma was significantly less than Pi M1M1 plasma (ZZ 78 +/- 1% vs. M1M1 95 +/- 1%, P less than 0.001) as was purified Z type alpha 1AT (ZZ, 63 +/- 2% vs. M1M1 86 +/- 2%, P less than 0.001). Sodium dodecyl sulfate (SDS) gel comparisons of the complexes formed with M1-type alpha 1AT and Z-type alpha 1AT with elastase demonstrated the Z alpha 1AT-elastase complexes were less stable than the M1 alpha 1AT-elastase complexes, thus releasing some of the enzyme to continue to function as a protease. Consistent with these observations, the K association of purified Z-type alpha 1AT for neutrophil elastase was lower than that of M1-type alpha 1AT (ZZ 4.5 +/- 0.3 X 10(6) M-1s-1 vs. M1M1 9.7 +/- 0.4 X 10(6) M-1s-1, P less than 0.001), suggesting that for the population of alpha 1AT molecules, the active Z-type molecules take more than twice as long as the active M1-type alpha 1AT to inhibit neutrophil elastase. Consequently, not only is there less alpha1AT in PiZZ individuals, but the population of Z-type alpha1AT molecules is less competent as an inhibitor of neutrophil elastase than M1-type alpha1AT molecules. This combination of defects suggests that PiZZ individuals have far less functional antielastase protection than suggested by the reduced concentrations of alpha1AT alone, further explaining their profound risk for development of emphysema.

In vitro generation of tumoricidal properties in human alveolar macrophages following interaction with endotoxin.

Human alveolar macrophages (AM) obtained by bronchoalveolar lavage from healthy nonsmoking donors exhibited primarily low levels of cytolytic activity against allogeneic tumor target cells. These AM acquired enhanced capacity to kill tumor cells following a 24-hr incubation in vitro with endotoxin [lipopolysaccharide (LPS)]. Maximal tumoricidal activity of LPS-activated AM as measured by lysis of tumor target cells was obtained after incubation with tumor cells for 72 hr. LPS-activated AM lysed allogeneic tumor cell lines of different origins but did not affect normal, nonneoplastic cells. We conclude that LPS induces human AM to become tumoricidal. This method should be useful in studies on therapeutic agents enhancing AM-mediated cytotoxicity in situ.

Enzyme immunoassay of thromboxane B2.

An immunoassay for thromboxane B2 was developed in which the hapten molecule was labeled with beta-galactosidase. The immunoprecipitate formed after competition between enzyme-labeled and unlabeled thromboxane B2 was subjected to a fluorometric assay of beta-galactosidase. Thromboxane B2 was detectable in the range of 0.1-30 pmol. Both enzyme immunoassay and radioimmunoassay showed essentially the same cross-reactivities with other prostaglandins and their metabolites when the same antibody was used. Known amounts of thromboxane B2 were added to human plasma, and the sample was applied to an octadecyl silica column. The extract was analyzed by enzyme immunoassay to examine the correlation between the added (x) and measured (y) thromboxane B2 (y = 1.09x + 11.07 pmol/ml, r = 0.99). A satisfactory correlation was observed between radioimmunoassay (x) and enzyme immunoassay (y) (y = 0.92x + 4.64 pmol/ml, r = 0.96). The validity of enzyme immunoassay was also confirmed by gas chromatography-mass spectrometry of a dimethylisopropylsilyl ether derivative of thromboxane B2 methyl ester. The method was applicable to the assay of thromboxane B2 produced from endogenous precursor during thrombin-induced aggregation of human platelets.

Chymase is a potent chemoattractant for human monocytes and neutrophils.

Chymase is a major chymotrypsin-like serine protease expressed in the secretory granules of mast cells in many mammalian species. In this study, we revealed the chemotactic activity of chymase for human mononuclear cells and neutrophils with a 48-well microchemotaxis chamber technique. Human chymase showed the potent chemotactic activity for monocytes and neutrophils dose-dependently in a concentration range from 0.1 to 10 microg/mL, corresponding to about 4-400 microM. The activity was as potent as that of N-formyl-methionyl-leucyl-phenylalanine. Chymase also stimulated cell migration of lymphocytes and purified T cells, but checkerboard analysis revealed that the effect was chemokinetic rather than chemotactic. Inhibition of chymase activities with chymase inhibitors, such as antileukoprotease and Bowman-Birk soybean trypsin inhibitor, significantly inhibited the chemotactic activity of chymase, suggesting that the proteolytic activity of chymase participates in the chemotactic activity. Our results suggest that mast cell chymase acts as a chemoattractant, and may play a role in the accumulation of inflammatory cells in development of the chronic inflammatory responses of allergic and nonallergic diseases.

Comparison of suppressive effects of a new anti-inflammatory compound, FR167653, on production of PGE2 and inflammatory cytokines, human monocytes, and alveolar macrophages in response to endotoxin.

FR167653 [1-[7-(4-fluorophenyl)-1,2,3,4-tetrahydro-8 (4-pyridyl) pyrazoro [5-1-c] [1,2,4] triazin-2-yl]-2-phenylethanedion sulfate monohydrate] was developed to inhibit proinflammatory cytokine production. However, the effects of FR167653 on prostanoid production are unclear. We investigated the effect of FR167653 on proinflammatory cytokine and prostaglandin (PG) production by lipopolysaccharide (LPS)-stimulated human peripheral blood monocytes and alveolar macrophages (AM) from the same individuals, and compared the effects in monocytes and AM. FR167653 inhibited interleukin-1beta and tumor necrosis factor alpha production. The effect on PGE2 production was assessed by four parameters. FR167653 inhibited PGE2 synthesis and LPS induction of cyclooxygenase activity. Western and Northern blot analyses revealed that LPS induction of cyclooxygenase-2 expression was attenuated by this compound. The suppression in monocytes was greater than that in AM. We concluded that the reduction of LPS-induced PGE2 synthesis by FR167653 was due to inhibition of cyclooxygenase-2 production. These results show that FR167653 may be therapeutically useful for inhibiting production of both inflammatory cytokines and PG production in inflammatory diseases.

Plasma-cell dyscrasia with polyneuropathy and endocrine disorders associated with dysfunction of salivary glands.

A case of plasma-cell dyscrasia with polyneuropathy and endocrine disorders that showed dysfunction of the salivary glands is reported. A 49-year-old Japanese man noticed swelling of the cervical lymph nodes and numbness in the lower extremities in May 1983. Histological examination of the enlarged cervical lymph nodes revealed many follicles penetrated by radial capillaries and proliferation of capillaries and plasma cells in the interfollicular area, forming Castleman disease-like lesions. The patient complained of a dry mouth and noticed swelling of the submandibular salivary gland in April 1984. Microscopic examination of this gland revealed an angiofollicular lymphoid lesion resembling that in the lymph nodes. He also suffered from an endocrine disturbance characterized by increased serum adrenocorticotropic hormone and impotence. This is the second reported case of plasma-cell dyscrasia with polyneuropathy and endocrine disorders that showed dysfunction of exocrine secretion. This case indicates that attention must be paid to organs of exocrine secretion as well as of endocrine secretion in this disease.

PGE2 and PGF2 alpha content in bronchoalveolar lavage fluid obtained from patients with eosinophilic pneumonia.

Cell differential, prostaglandins (PGs) E2 and F2 alpha in the bronchoalveolar lavage fluid (BALF) in two patients with eosinophilic pneumonia were measured at different times in the course of the disease. Results showed markedly increased numbers of eosinophils and increased content of prostaglandin (PG) E2 in BALF obtained from the patients with eosinophilic pneumonia compared to that of normal volunteers. Interestingly, the increased content of PGE2 in BALF obtained from the patients reverted to normal range with corticosteroid treatment. This change in PGE2 content in BALF was accompanied by normalization of number and percentage of eosinophils in BALF. These findings indicated that PGE2 level in lower respiratory tract of patients with eosinophilic pneumonia may be related to an increased number of eosinophils.

Differential cell analysis in bronchoalveolar lavage fluid from pulmonary lesions of patients with tuberculosis.

To obtain information on the cellular reactions to Mycobacterium (M) tuberculosis in the lung, we analyzed the cells in bronchoalveolar lavage (BAL) fluid from pulmonary lesions in comparison with those in BAL fluid from nonaffected regions of the lungs, and control lungs, and in peripheral blood of patients with tuberculosis. Neutrophils and lymphocytes were increased in number in BAL fluid from affected lesions of the lungs of patients with miliary tuberculosis and patients with active pulmonary tuberculosis compared with those in BAL fluid from control patients, but the number of alveolar macrophages was decreased in BAL fluid from tuberculous lesions. However, the numbers of these cells were not changed in the BAL fluid from nonaffected regions of the lungs of patients with active or inactive pulmonary tuberculosis. The numbers of lymphocytes were decreased and the numbers of monocytes were increased in peripheral blood from patients with miliary tuberculosis and with active tuberculosis, indicating inverse changes in the numbers of lymphocytes and monocytes in the peripheral blood to those in the BAL fluid of patients with tuberculosis. These results indicate characteristic redistributions of immune or inflammatory cells in response to infection with M tuberculosis and suggest that these changes are important for understanding the pathophysiology of pulmonary tuberculosis.

Structure and properties of albumin Tokushima and its proteolytic processing by cathepsin B in vitro.

Albumin Tokushima is a Japanese genetic variant of human serum albumin. Two homozygous and 6 heterozygous subjects with this variant were found in a family. Albumin Tokushima was purified from sera of the homozygous subjects. Its amino acid composition and amino-terminal sequence were determined and compared with those of a normal serum albumin. Albumin Tokushima with the amino-terminal sequence of Arg-Gly-Val-Phe-His-Arg-Asp-Ala-His-Lys-Ser-Glu-Val-Ala-His-Arg-Phe-Lys- Asp- Leu-Gly-Glu-Glu-Asn-Phe was found to be the same abnormal proalbumin as proalbumin Lille (Abdo, Y. et al. (1981) FEBS Lett. 131, 286-288). The isoelectric points of albumin Tokushima were pH 4.70 and 4.90 as compared with pH 5.05 and 5.25 of a normal serum albumin. Albumin Tokushima was converted to normal serum albumin by purified cathepsin B in vitro. Albumin Tokushima can bind Ni2+ at 4 degrees C but binds little at 37 degrees C.

Thrombin promotes fibroblast proliferation during the early stages of experimental radiation pneumonitis.

Huang, L., Ogushi, F., Tani, K., Ogawa, H., Kawano, T., Endo, T., Izumi, K., Ueno, J., Nishitani, H. and Sone, S. Thrombin Promotes Fibroblast Proliferation during the Early Stages of Experimental Radiation Pneumonitis. Radiat. Res. 156, 45-52 (2001). To clarify the role of thrombin in the pathogenesis of radiation-induced pneumonitis, we measured the thrombin activity and fibroblast growth-inducing activity in bronchoalveolar lavage fluid obtained from the irradiated lungs of rats at 1, 2, 4, 8 and 18 weeks after irradiation. Thrombin activity was not detected in the bronchoalveolar lavage fluid from unirradiated rats, but the bronchoalveolar lavage fluid from irradiated rats showed significantly increased thrombin activity which reached a maximum at 4 weeks after treatment. Higher fibroblast growth-inducing activity was detected in the bronchoalveolar lavage fluid from irradiated rats at 4 and 18 weeks than in fluid from unirradiated rats. Bronchoalveolar lavage fluid from irradiated rats that were pretreated with the thrombin inhibitors antithrombin III and argatroban showed significantly inhibited fibroblast growth-inducing activity and thrombin activity at 4 weeks. However, these thrombin inhibitors did not inhibit fibroblast growth-inducing activity in bronchoalveolar lavage fluid from irradiated rats at 18 weeks. Purified rat thrombin similarly induced proliferation of fibroblasts derived from irradiated and unirradiated rats. These findings suggest that thrombin may play an important role as a fibroblast growth-inducing factor during the early stages of radiation pneumonitis.

Augmentation of lung antineutrophil elastase capacity with recombinant human alpha-1-antitrypsin.

To evaluate the potential use of recombinant DNA-produced alpha-1-antitrypsin (alpha-1-AT) to augment the lung antineutrophil elastase defenses in alpha-1-AT deficiency, we compared the kinetics of intravenously administered recombinant produced alpha-1-AT (r alpha-1-AT) and purified normal human plasma alpha-1-AT (p alpha-1-AT) in the blood and lung of rhesus monkeys. The r alpha-1-AT was produced in yeast transformed with an expressing plasmid containing a full-length human alpha-1-AT complementary deoxyribonucleic acid and purified to greater than 99% homogeneity. The r alpha-1-AT has a molecular weight of 45,000, no carbohydrates, and is identical in sequence to normal plasma alpha-1-AT except for an additional N-terminal acetylmethionine. Despite its lack of carbohydrates, the r alpha-1-AT inhibited human neutrophil elastase with an association rate constant similar to that of p alpha-1-AT. Rhesus monkeys were infused intravenously with 120 mg/kg of r alpha-1-AT (n = 13) or p alpha-1-AT (n = 12) and the serum, urine, and lung epithelial lining fluid (ELF) concentrations of these molecules quantified at various intervals.(ABSTRACT TRUNCATED AT 250 WORDS)

Successful treatment of metastatic cardiac lymphoma with complete A-V block.

Although involvement of the heart is not a rare manifestation of malignant lymphoma, most cases are diagnosed by postmortem examination. In the present article, we describe a man with metastatic cardiac lymphoma with complete A-V block successfully treated by resection of the heart tumor and sequential combination chemotherapy with cyclophosphamide, doxorubicin, vincristine and predonisolone and radiation therapy. Combination modality resulted in complete disappearance of signs of heart failure and A-V block. Our experience indicated that early diagnosis and combination modality can obtain long survival in case of metastatic cardiac lymphoma.

A case with small cell carcinoma of the esophagus: measurement of tumor markers, including pro-gastrin-releasing peptide.

Small cell carcinoma of the esophagus is a rare clinical entity and the accumulation of information is necessary to clarify its clinical behavior. We report a 69-year-old Japanese man with this rare disease with systemic metastases, including liver, bone and lymphnodes. The patient was treated with systemic chemotherapy consisting of 300 mg/m2 of carboplatin on day 1, and 80 mg/m2 of etoposide on days 1, 2 and 3. Although transient relief of subjective symptoms was obtained, the disease showed systemic progress, and the patient died on day 25 of chemotherapy. During the clinical course of the disease, serum pro-gastrin-releasing peptide (proGRP) decreased upon systemic chemotherapy from elevated level (54.6 pg/ml) to normal range (19.2 pg/ml). Further study is warranted to examine whether measurement of serum proGRP may yield valuable information on the diagnosis and monitoring activities of esophageal small cell carcinoma.

Protease-induced leukocyte chemotaxis and activation: roles in host defense and inflammation.

The migration of leukocytes such as neutrophils, monocytes and lymphocytes into inflamed lesions is one of the critical events of inflammation. Although the traditional function of neutrophil-derived antimicrobial proteases is to ingest and kill bacteria, some neutrophil serine proteases have been shown to induce leukocyte migration and activation. Mast cell-derived chymase also has the chemotactic activity for leukocytes. During the acute phase of inflammatory and allergic diseases, the predominantly migrated cells are neutrophils and mast cells, respectively, and in the subsequent chronic phase, monocytes and lymphocytes are mainly migrated. The chemotactic activity for monocytes and lymphocytes of neutrophil-derived serine proteases and mast cell-derived chymase may have a role in switching acute inflammation to chronic inflammation and delayed-type hypersensitivity. Recently, aminopeptidase N and endothelin were shown to induce chemotactic migration of leukocytes. Thus, protease-induced leukocyte chemotaxis and activation may play an important role in immunologic events of inflammatory and allergic diseases.

Age-related increase of autoantibodies to interleukin 1 alpha in healthy Japanese blood donors.

Although autoantibodies to interleukin-1 alpha (IL-1 alpha autoantibodies) are known to be present in sera of apparently healthy humans, their frequency of occurrence and significance are unclear. To determine the prevalence of detectable IL-1 alpha autoantibodies in normal human blood, we screened the plasma of blood donors (6290 subjects: 3977 men and 2313 women, ages 16 to 64 yr) by a radioimmununoassay which we developed using a method that could detect over 5 ng/ml. Moreover, we investigated immunoglobulin class of IL-1 alpha autoantibodies and also their function. IL-1 alpha autoantibodies were detected in 14.6% of the 6290 donors. Their frequency was higher in males than females (16.6% vs. 11.2%, p < 0.01) and increased with age in both sexes. The proportion of subjects with a high IL-1 alpha autoantibodies titers also increased with age. We showed that IL-1 alpha autoantibodies were of the IgG class and that they had neutralizing function to IL-1 alpha by receptor assay. Neutralizing activity was only shown in plasma with concentration of IL-1 alpha autoantibodies, the level of which was over 1000 ng/ml. The affinity of the IL-1 alpha autoantibodies in plasma was between 2.1 x 10(-10) and 1.2 x 10(-9) M (mean 6.4 x 10(-10)M). Our results provide a basis for comparison with IL-1 alpha autoantibodies prevalence between healthy states and disease states, and suggest that IL-1 alpha autoantibodies may play a significant role in modulating the effects of excessive IL-1 alpha at local site or in systemic regions.

A case of sarcoidosis associated with chronic eosinophilic pneumonia.

A 38-year-old man was hospitalized in our university hospital because of pulmonary opacities with bilateral hilar and mediastinal lymphadenopathy seen on chest radiograph. Eosinophilia was observed in the circulation and bronchoalveolar lavage (BAL) fluid. Histological examination revealed noncaseating epithelioid granulomas and eosinophilic infiltration in the lung. Based on these findings, a diagnosis of sarcoidosis combined with chronic eosinophilic pneumonia was made. The infiltrates on chest radiograph and BAL eosinophilia were promptly reduced with corticosteroid therapy, but only mild reduction was observed in diffuse nodular shadows and hilar and mediastinal lymphadenopathy, and high amounts of lymphocytes in BAL fluid remained. Increased IFN-gamma, IL-4 and IL-5 were detected in the BAL fluid, and corticosteroid therapy reduced IL-4 and IL-5 (Th-2 cytokines) but not IFN-gamma (Th-1 cytokine). These cytokine levels in BAL fluid were intimately correlated with the clinical course of sarcoidosis and chronic eosinophilic pneumonia.

Interleukin-8 in bronchoalveolar lavage fluid of patients with diffuse panbronchiolitis or idiopathic pulmonary fibrosis.

This study was designed to clarify the contribution of IL-8 as a specific neutrophil chemotactic factor in the human respiratory tract in various pulmonary diseases. The neutrophil chemotactic activity (NCA), neutrophil counts and IL-8 concentration in the bronchoalveolar lavage fluid (BALF) obtained from normal volunteers (NV), control patients (CP), patients with diffuse panbronchiolitis (DPB) and patients with idiopathic pulmonary fibrosis (IPF) were examined. Neutrophil counts, NCA and IL-8 concentration in BALF obtained from patients with DPB or IPF was significantly higher than that from NV or CP. The IL-8 concentration correlated with neutrophil count and also correlated with NCA in BALF from patients with IPF, whereas there was no correlation between these factors in BALF from DPB. These results suggest that the contribution of IL-8 to neutrophil accumulation of the lower respiratory tract is different between IPF and DPB.

Thrombin stimulates platelet-derived growth factor release by alveolar macrophages in rats--significance in bleomycin-induced pulmonary fibrosis.

Thrombin is a multifunctional enzyme generated at sites of vascular injury, and is known to be increased in the lungs in some types of fibrotic lung disease. In this study, to determine whether thrombin is associated with fibroblast growth and pulmonary fibrosis in these disorders, we examined whether a growth factor for fibroblasts (platelet-derived growth factor, PDGF) was released by thrombin-stimulated alveolar macrophages (AM). The culture supernatants of rat AM stimulated with 1 or 10 U/ml of thrombin showed a significant increase in fibroblast growth-stimulating activity (FGA). Pretreatment of the AM supernatant with anti-PDGF-AA antibody significantly decreased the FGA, but pretreatment with anti-PDGF-BB antibody did not. The supernatants of AM stimulated with thrombin also increased the growth of fibroblasts from the lungs of rats with bleomycin-induced lung injury. These results indicate that thrombin stimulates AM to release PDGF-AA, which is responsible, at least in part, for fibroblast growth and the development of pulmonary fibrosis in some types of fibrotic lung disease.