Yuh Fukuda

Gelatinase B Is Required for Alveolar Bronchiolization after Intratracheal Bleomycin

Increased expression of matrix metalloproteinases, particularly gelatinase B (MMP-9), has been described in the lungs in pulmonary fibrosis. Intratracheal bleomycin is often used experimentally to produce lesions resembling human fibrosing alveolitis. To assess the role of gelatinase B in bleomycin-induced fibrosing alveolitis, we instilled bleomycin intratracheally into gelatinase B-deficient mice and gelatinase B+/+ littermates. Twenty-one days after bleomycin the two groups of mice were indistinguishable in terms of pulmonary histology and total lung collagen and elastin. However, the lungs of gelatinase B-deficient mice showed minimal alveolar bronchiolization, whereas bronchiolization was prominent in the lungs of gelatinase B+/+ mice. Gelatinase B was identified immunohistochemically in terminal bronchiolar cells and bronchiolized cells 7 and 14 days after bleomycin in gelatinase B+/+ mice, and whole lung gelatinase B mRNA was increased at the same times. Many bronchiolized cells displayed Clara cell features by electron microscopy. Some bronchiolized cells stained with antibody to helix transcription factor 4, a factor associated with the ciliated cell phenotype. Thus, fibrosing alveolitis develops after intratracheal bleomycin irrespective of gelatinase B. However, gelatinase B is required for alveolar bronchiolization, perhaps by facilitating migration of Clara cells and other bronchiolar cells into the regions of alveolar injury.

Abnormalities in elastic fibers and other connective-tissue components of floppy mitral valve

Histologic, immunohistochemical, and ultrastructural studies were performed on 12 floppy mitral valves, 4 mitral valves showing focal myxomatous changes without prolapse, and 3 normal mitral valves. All floppy mitral valves were thickened by deposits of proteoglycans and also showed diverse structural abnormalities in collagen and elastic fibers. From these observations we conclude that (1) the structure of all major components of connective tissue in floppy mitral valves is abnormal; (2) alterations in collagen and accumulations of proteoglycans are nonspecific changes that may be caused by the abnormal mechanical forces to which floppy mitral valves are subjected because of their excessively large surface area; (3) the presence of excessive amounts of proteoglycans may interfere with the normal assembly of collagen and elastic fibers; (4) abnormalities of elastic fibers resemble those in other conditions characterized by structural dilatation or tissue expansion; and (5) alterations in elastin could result from defective formation, increased degradation, or both.

Wound healing involves induction of cyclooxygenase-2 expression in rat skin.

Cyclooxygenase (COX), an enzyme essential for prostaglandin biosynthesis, has two isoforms, COX-1 and -2. We investigated temporal and spatial changes in localization of these two COX proteins and mRNAs after excisional injury in rat skin. We also quantified the expression of these proteins and studied the effects of a specific COX-2 inhibitor on healing. Immunohistochemistry and in situ hybridization respectively indicated that the COX-2 protein and mRNA were expressed mainly within the basal layer of the epidermis, peripheral cells in the outer root sheath of hair follicles, and fibroblast-like cells and capillaries near epidermal wound edges. Much less intense expression was observed in normal skin than in injured skin. Western analysis demonstrated marked induction of COX-2 protein beginning within 12 hours and peaking 3 days after injury. In contrast, localization of COX-1 protein and mRNA, as well as the amount of protein expression, showed no significant change during wound healing. Administration of the COX-2 inhibitor delayed re-epithelialization in the early phase of wound healing and also inhibited angiogenesis. Thus, COX-2 induction may be important in cutaneous wound healing.

Effect of Helicobacter pylori infection on ghrelin expression in human gastric mucosa.

OBJECTIVES:One of the counter-effects of Helicobacter pylori eradication therapy is subsequent obesity. Ghrelin is a recently discovered growth hormone releasing peptide. This endogenous secretagogue increases appetite and facilitates fat storage. The majority of circulating ghrelin is produced in the gastric mucosa. Therefore, we aimed at investigating changes in ghrelin immunoreactivity in gastric mucosa tissues of patients infected with H. pylori.METHODS:Sixty-one patients with H. pylori infection (25 cases each of duodenal and gastric ulcer, and 11 cases of gastritis) and 22 healthy controls without H. pylori infection were included in the study. H. pylori-infected patients received standard proton pump-based triple therapy followed by histological examination and 13C-urea breath test to confirm H. pylori eradication. H. pylori was eradicated in 50 out of 61 patients. Biopsy specimens were obtained from antrum and corpus before and 3 months following eradication. Ghrelin expression was evaluated immunohistochemically with an anti-ghrelin antibody, and the number of ghrelin-positive cells determined per 1 mm2 of the lamina propria mucosa.RESULTS:There was no relationship between ghrelin immunoreactivity and body weight or body mass index for healthy controls. The number of ghrelin-positive cells was significantly lower for H. pylori-infected patients than for healthy controls. However, the ghrelin-positive cell number increased significantly following H. pylori eradication without significant change in severity of atrophy.CONCLUSIONS:These data indicated that H. pylori infection affected ghrelin expression. After H. pylori eradication, gastric tissue ghrelin concentration increased significantly. This could lead to the increased appetite and weight gain seen following H. pylori eradication.

Long-term systemic therapy of Fabry disease in a knockout mouse by adeno-associated virus-mediated muscle-directed gene transfer

Fabry disease is a systemic disease caused by genetic deficiency of a lysosomal enzyme, α-galactosidase A (α-gal A), and is thought to be an important target for enzyme replacement therapy. We studied the feasibility of gene-mediated enzyme replacement for Fabry disease. The adeno-associated virus (AAV) vector containing the α-gal A gene was injected into the right quadriceps muscles of Fabry knockout mice. A time course study showed that α-gal A activity in plasma was increased to ≈25% of normal mice and that this elevated activity persisted for up to at least 30 weeks without development of anti-α-gal A antibodies. The α-gal A activity in various organs of treated Fabry mice remained 5–20% of those observed in normal mice. Accumulated globotriaosylceramide in these organs was completely cleared by 25 weeks after vector injection. Reduction of globotriaosylceramide levels was also confirmed by immunohistochemical and electronmicroscopic analyses. Echocardiographic examination of treated mice demonstrated structural improvement of cardiac hypertrophy 25 weeks after the treatment. AAV vector-mediated muscle-directed gene transfer provides an efficient and practical therapeutic approach for Fabry disease.

Vascular Endothelial Growth Factor165 Resolves Glomerular Inflammation and Accelerates Glomerular Capillary Repair in Rat Anti–Glomerular Basement Membrane Glomerulonephritis

Vascular endothelial growth factor (VEGF) is essential for maintenance of the glomerular capillary network. The present study investigated the effects of VEGF in rats with progressive crescentic glomerulonephritis (GN). Necrotizing and crescentic GN was induced in rats by injection of anti-rat glomerular basement membrane (GBM) antibody. The alterations of glomerular capillaries and glomerular VEGF expression were assessed. In addition, the effects of continuous VEGF165 administration (10 microg/100 g per d) on glomerular capillaries, glomerular inflammation, and the course of crescentic GN were examined. The appropriate timing of VEGF administration in progressive GN also was evaluated. In anti-GBM GN, necrotizing and crescentic glomerular lesions occurred by day 7, and newly formed necrotizing lesions reoccurred by week 3. Expression of VEGF was markedly reduced in necrotizing and crescentic lesions. Capillary repair was impaired after capillary destruction in necrotizing and crescentic glomeruli, which rapidly progressed to sclerotic glomeruli with chronic renal failure. In contrast, in the rats that received VEGF165 administration from day 7, the necrotizing and crescentic lesions recovered and renal function significantly improved in week 4. This was evident by proliferating endothelial cells and glomerular capillary repair. In addition, VEGF administration decreased intercellular adhesion molecule-1 and monocyte chemoattractant protein-1 expression in glomeruli (particularly on endothelial cells), reduced glomerular infiltrating CD8-postive and ED-1-positive cells, and inhibited the newly formed necrotizing lesions. VEGF administration was apparently effective against both the inflammatory and necrotizing glomerular lesions. These results suggest that VEGF administration resolves glomerular inflammation and accelerates glomerular recovery in the progressive necrotizing and crescentic GN. The therapeutic application of VEGF may be clinically useful for severe GN accompanied by extensive glomerular inflammation and endothelial injury.

Immunohistochemical and gelatin zymography studies for matrix metalloproteinases in bleomycin‐induced pulmonary fibrosis

The role of various matrix metalloproteinases (MMP) and tissue Inhibitor of metalloprotelnases‐2 (TIMP‐2), and the gelatholytic activities of MMP involved in the process of bleomycin‐induced pulmonary fibrosis in rabbits were Investigated. Male Japanese white rabbits were intubated with tracheal tubes under anesthesia, and bleomycin hydrochloride in sterile saline or only sterile saline was administered through the tracheal tubes. The animals were killed 1, 3, 7, 14 and 28 days after the administration of bleomycln (n = 3) or saline (n = 2). Light microscopic lmmunohistochemlstry for MMP‐1 (interstitial collagenase), MMPP (gelatinase A), MMP‐9 (gelatinase B) and TIMP‐2 was performed. The gelatinolytic activities of lung tissue homogenates were studied by gelatin zymography. In the early stages, the gelatholytic activity of MMP‐9 was predominant. MYP‐9 localized in the infiltrating neutrophils, macrophages, bronchial and bronchiolar epithelial cells. The alveolar epithelial basement membrane was frequently disrupted in the early stages, where MMP‐9 possibly contributed to the disruption. In the late stages, the gelatinolytic activities of the latent and active forms of MMP‐2 were predominant, and MMPP localized in the regenerated alveolar epithelial cells in addition to the bronchial epithelial cells. MMP‐2, especially its active form, possibly plays a role in alveolar epithelial cell regeneration. The localization of MMP‐1 was similar to that of MMP‐9. TIMP‐2 localized in the epithelial cells and in some fibroblasts in fibro tic lesions. TIMP‐2 possibly plays a role in extracellular matrix deposition in balance with MMP.

Evolution of three patterns of intra‐alveolar fibrosis produced by bleomycin in rats

In pulmonary fibrosis, it is known that fibrotic changes develop in the intra‐alveolar spaces and that intra‐alveolar fibrosis can be classified into three patterns, namely intraalveolar buds, mural incorporation and obliterative changes. In order to clarify the evolution of intra‐alveolar fibrosis, immunohistochemical studies of extracellular matrix proteins and electron microscopic observations were made of the lungs of rats given a single intretracheal instillation of bleomycin. All three patterns of fibrosis developed in this model. Intra‐alveolar buds changed into globular lesions with dense collagen deposition, the surface of which was covered by alveolar epithelium. Electron microscopy revealed that the buds often contained spiraling collagen fibrils and numerous microfibrils, but not mature elastic fibres, beneath the regenerating epithelial lining cells; the epithelial basement membranes were discontinuous. In contrast, mural incorporation and obliterative changes ware associated with alveolar structural remodeling. Electron microscopically, these lesions had bundles of normal collagen fibrils, small elastic fibers, and continuous epithelial basement membranes. These results indicate that: (i) intra‐alveolar buds, that become intra‐alveolar collagen globules, with an unusual extracellular matrix, do not contribute to alveolar structural remodelling; and (ii) areas of mural incorporation and obliterative changes have the usual type of extracellular matrix and are essential for alveolar structural remodeling.

EXPERIMENTAL MESANGIOPROLIFERATIVE GLOMERULONEPHRITIS IN RATS INDUCED BY INTRAVENOUS ADMINISTRATION OF ANTI-THYMOCYTE SERUM

Focal glomerulonephritis was induced in rats, by a single intravenous injection of anti‐Thy‐1.1 antibody (ATS). One hour after the administration, the glomeruli of affected rats developed necrotic changes of the mesangial cells while after two hours, mesangiolytic changes appeared. From six days onwards, focal segmental mesangial proliferation which persisted until 30 days, occurred. This is thought to be the first report of experimental nephritis induced by pure anti‐mesangial antibody.

Significance of early intra-alveolar fibrotic lesions and integrin expression in lung biopsy specimens from patients with idiopathic pulmonary fibrosis

To study the pulmonary structural remodeling in idiopathic pulmonary fibrosis (IPF), ultrastructural, immunohistochemical, and light microscopic morphometric observations were made on 11 pulmonary biopsy specimens from patients with IPF. The morphometric study was done using sequentially cut tissue sections stained for keratin-alcian blue periodic acid-Schiff (PAS), fibronectin, and type IV collagen-alcian blue PAS. Most of the early fibrotic lesions, which were alcian blue- and fibronectin-positive, were intra-alveolar in location. Intra-alveolar fibrosis is considered to be essential for the fusion of alveolar walls in IPF. A strong reaction for integrin alpha 5 beta 1 and vinculin was found in epithelial cells and mesenchymal cells in areas of intra-alveolar fibrosis. These findings show that these cells are active in adhesion to fibronectin in areas of early intra-alveolar fibrosis. Some of the epithelial cells, including cytoplasmic hyaline-laden cells, showed evidence of inadequate adhesion to the extracellular matrix, and this may constitute one of the mechanisms of progression of fibrosis in IPF.