Cell-extracellular matrix interaction and extracellular matrix remodeling are known to be important in fetal lung development. We investigated the localization of matrix metalloproteinases (MMPs) in fetal rabbit lungs. Immunohistochemistry for type IV collagen, MMP-1, MMP-2, MMP-9, membrane type (MT) 1 MMP, and tissue inhibitor of metalloproteinase (TIMP)-2 and in situ hybridization for MMP-9 mRNA were performed. Gelatin zymography and Western blotting for MT1-MMP in lung tissue homogenates were also studied. MMP-1 and MT1-MMP were detected in epithelial cells, and MMP-2 and TIMP-2 were detected in epithelial cells and some mesenchymal cells in each stage. MMP-9 was found in epithelial cells mainly in the late stage. Gelatin zymography revealed that the ratio of active MMP-2 to latent MMP-2 increased dramatically during the course of development. MT1-MMP was detected in tissue homogenates, especially predominant in the late stage. These findings suggest that MMPs and their inhibitors may contribute to the formation of airways and alveoli in fetal lung development and that activated MMP-2 of alveolar epithelial cells may function to provide an extremely wide alveolar surface.

No abstract

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.

SUMMARY: 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. (Lab Invest 2002, 82:1503-1513.A fter skin injury, a complex series of events must proceed for the epidermal and dermal wound recovery. Keratinocytes at the edge of an epidermal wound migrate, proliferate, and differentiate to cover the exposed wound surface, and fibroblasts and capillaries produce a new granulation tissue (Clark, 1993;Martin, 1997). Each process may be regulated by many bioactive substances, including growth factors, extracellular matrix components, and eicosanoids. Eicosanoids such as prostaglandins (PGs), prostacyclins, and thromboxane have been implicated in wound healing in various tissues such as cornea (Joyce and Meklir, 1994), skin (Talwar et al, 1996), gastrointestinal tract (Zushi et al, 1996), and kidney (Cybulsky et al, 1992). In particular, PGE 2 , which constitutes the major PGs in human and rat skin (Jonsson and Änggård, 1972;Jouvenaz et al, 1970), affects keratinocyte proliferation (Lowe and Stoughton, 1977;Pentland and Needleman, 1986), differentiation (Evans et al, 1993), and angiogenesis in vivo together with PGE 1 (Form and Auerbach, 1983;Ziche et al, 1982). Talwar et al (1996) have found that synthetic PGE 2 facilitates fibrosis in vivo during healing of wounded rat skin. Furthermore, receptors for PGE 2 , E-prostanoid (EP) 2 , and/or EP 4 mediate the effect of PGE2 on keratinocyte growth (Konger et al, 1998). Indeed, EP 4 receptor mRNA showed upregulation in a fetal rabbit skin wound (Li et al, 2000).These findings indicate that PGE2 production is essential for cutaneous wound healing. PGs are formed by the combined actions of phospholipase, which releases arachidonic acid (AA) from cell membrane phospholipids, and cyclooxygenase (COX), which converts AA to PGs.Recently, several investigators have used molecular techniques to confirm the presence of two isoforms of COX, a constitu...

Molecular hydrogen (H(2)) is an efficient antioxidant that diffuses rapidly across cell membranes, reduces reactive oxygen species (ROS), such as hydroxyl radicals and peroxynitrite, and suppresses oxidative stress-induced injury in several organs. ROS have been implicated in radiation-induced damage to lungs. Because prompt elimination of irradiation-induced ROS should protect lung tissue from damaging effects of irradiation, we investigated the possibility that H(2) could serve as a radioprotector in the lung. Cells of the human lung epithelial cell line A549 received 10 Gy irradiation with or without H(2) treatment via H(2)-rich PBS or medium. We studied the possible radioprotective effects of H(2) by analyzing ROS and cell damage. Also, C57BL/6J female mice received 15 Gy irradiation to the thorax. Treatment groups inhaled 3% H(2) gas and drank H(2)-enriched water. We evaluated acute and late-irradiation lung damage after H(2) treatment. H(2) reduced the amount of irradiation-induced ROS in A549 cells, as shown by electron spin resonance and fluorescent indicator signals. H(2) also reduced cell damage, measured as levels of oxidative stress and apoptotic markers, and improved cell viability. Within 1 wk after whole thorax irradiation, immunohistochemistry and immunoblotting showed that H(2) treatment reduced oxidative stress and apoptosis, measures of acute damage, in the lungs of mice. At 5 mo after irradiation, chest computed tomography, Ashcroft scores, and type III collagen deposition demonstrated that H(2) treatment reduced lung fibrosis (late damage). This study thus demonstrated that H(2) treatment is valuable for protection against irradiation lung damage with no known toxicity.

Objective (range, 5-47 months) 5%) had ILD-preceding myositis, and 4 (50%) had simultaneous onset. Chest high-resolution computed tomography frequently showed lung-base predominant ground glass opacities (GGO) with volume loss. The results of surgical lung biopsies indicated that 4 patients had nonspecific interstitial pneumonia (NSIP) and/or organizing pneumonia (OP) patterns. All but 1 received corticosteroid therapy, and 6 patients were also given cyclosporin. The mean duration of follow-up was 22 months

Background-Prostaglandin endoperoxide synthase/cyclooxygenase (COX) is the key enzyme in gastric mucosal protection and repair but its cellular localisation in the human stomach is still unclear. Aims-To investigate immunohistochemically the cellular distribution of COX-1 and COX-2 proteins in the human stomach with or without gastritis or ulceration. Patients and methods-Tissues were obtained by surgical resection of gastric ulcers associated with perforation (n=9) or by biopsy from Helicobacter pylori positive patients with gastric ulcers (n=45) and H pylori negative healthy subjects (n=15). COX expression was detected by semiquantitative reverse transcriptionpolymerase chain reaction (RT-PCR), western blotting, and light and electron microscopic immunohistochemistry. Results-COX-2 mRNA and protein were detected in gastric ulcer tissues but not in intact gastric mucosa. COX-1 mRNA and protein were detected in the intact mucosa. COX-2 immunostaining was exclusively localised in macrophages and fibroblasts between necrotic and granulation tissues of the ulcer bed. The percentage of COX-2 expressing cells was significantly higher in open than in closed ulcers, and in gastritis than in gastric mucosa without H pylori infection. COX-1 immunoreactivity localised in lamina propria mesenchymal cells was similar in various stages of ulcer disease and in intact gastric mucosa. Electron microscopic immunohistochemistry revealed both COX-1 and COX-2 on the luminal surfaces of the endoplasmic reticulum and nuclear envelope of macrophages and fibroblasts. Conclusions-Our results showed that COX-2 protein was induced in macrophages and fibroblasts in gastric ulcers and H pylori related gastritis, suggesting its involvement in the tissue repair process. (Gut 2000;46:782-789)

No abstract