Fumiyuki Kuze

Serum eosinophil cationic protein as a marker of eosinophilic inflammation in asthma

The serum level of eosinophil cationic protein (ECP) has been used as a clinical marker in asthma, on the assumption that it reflects ongoing eosinophilic inflammation of the airways. However, only a few studies have investigated this issue, using bronchial secretions but not tissue specimens.

Effect of oestrogen on Mycobacterium avium complex pulmonary infection in mice

The purpose of the present study was to elucidate the role of oestrogen in the pathogenesis of Mycobacterium avium complex (MAC) pulmonary disease, which occurs most frequently in postmenopausal women. The study was carried out in a murine infectious model using ovariectomized DBA/2 female mice. Infection with MAC was established by intratracheal administration of bacilli. In some experiments, ovariectomized mice were treated with exogenous 17β‐estradiol (E2). The number of bacilli in the lungs of infected mice which received ovariectomy was significantly larger than that in the lungs of sham‐operated control mice, and treatment of ovariectomized mice with exogenous E2 restored the burden of bacilli to the same level as that in the sham‐operated control mice. We next examined the effect of E2 in vitro using bone marrow‐derived macrophages obtained from DBA/2 female mice. The macrophages showed bacteriostatic activity against MAC after treatment with interferon‐gamma (IFN‐γ) and this activity was further enhanced by the exogenous addition of E2 to the culture medium. In parallel with these findings, E2 augmented the production of reactive nitrogen intermediates (RNI) by macrophages pretreated with IFN‐γ and stimulated with MAC, as shown by evaluating nitrite production and inducible nitric oxide synthase mRNA expression. These findings taken together suggest that absence of endogenous oestrogen appears to be responsible for the development of MAC pulmonary disease in this mouse model and that the enhancement by E2 of anti‐MAC activity of murine macrophages induced through increased RNI production may play some role in resistance to MAC infection.

Reciprocal effects of epidermal growth factor and transforming growth factor β on the anchorage-dependent and -independent growth of A431 epidermoid carcinoma cells

The effects of epidermal growth factor (EGF) and transforming growth factor beta (TGF beta) on the growth of A431 epidermoid carcinoma cells were studied. Whereas the monolayer growth of A431 cells was inhibited by EGF, it was stimulated by TGF beta. Contrary to the effects on the monolayer growth, EGF stimulated the soft agar growth of A431 cells. The stimulatory effects of TGF beta on the anchorage-dependent growth were antagonized by EGF and those of EGF on anchorage-independent growth were antagonized by TGF beta. These results suggest that both factors not only convey the proliferative signals to A431 cells but also induce phenotypic changes, resulting in a preference for either anchorage-dependent or anchorage-independent growth. Moreover, as the stimulatory effects of EGF on the soft agar growth of A431 cells paralleled its reported stimulatory effects on their in vivo growth, it is also suggested that in vivo responses of cells to certain growth factors may correlate better with their responses in soft agar culture than with those in monolayer culture.

Late respiratory response and associated eosinophilic inflammation induced by repeated exposure to toluene diisocyanate in guinea pigs

OBJECTIVE The study was designed to establish an animal model of toluene diisocyanate (TDI)-induced late respiratory response and to investigate airway inflammatory cell dynamics in this model. METHODS Guinea pigs were exposed to 2, 4-TDI dissolved in ethyl acetate by nasal application according to three schedules. Schedule 1 consisted of sensitization and multiple challenge (n = 58): 10% TDI was applied once daily for 7 days (sensitization) followed by challenges with 5% TDI once weekly for 4 weeks. Schedule 2 consisted of sensitization only (n = 5): 10% TDI was applied once daily for 7 days. Schedule 3 consisted of single challenge only (n = 12): 5% TDI was applied only once. As controls, ethyl acetate was applied according to the three schedules described above. Each animal was premedicated with metyrapone before each challenge. Bronchoalveolar lavage and histologic examination were performed at various times after the last challenge. RESULTS Schedule 1 induced immediate and late respiratory responses at a prevalence of 63% and 56%, respectively. Schedules 2 and 3 induced an immediate response in some animals but no late response. Neither immediate nor late response was observed in control animals. All of the subgroups of schedule 1 that developed late responses (examined at 2, 3, 6, 24 and 168 hours) showed a significant increase of eosinophils in bronchoalveolar lavage fluid and tissue compared with the corresponding control of each (examined at the same time points). Two of the subgroups with late responses (examined at 3 and 6 hours) were compared with their corresponding subgroups, which were given the same treatment, failed to develop late response, and were examined at the same time points; they again proved to have a significant increase of eosinophils in both samples. Subgroups of schedule 1 without late response (30 minutes, 3 and 6 hours), schedule 2 (6 hours), or schedule 3 (2 and 6 hours) did not show significant changes in lavage or tissue cell composition, except for the schedule 1 subgroup examined at 6 hours, which showed a significant increase of eosinophils only in the tissue compared with its control. CONCLUSIONS Sensitization and multiple challenge with TDI induced immediate and/or late respiratory responses at a high prevalence in guinea pigs. Eosinophilic but not neutrophilic inflammation was involved in the late response.

Plasmid Profiles of Mycobacterium avium Complex Isolated from Swine

Twenty strains of Mycobacterium avium complex (MAC) isolated from swine and five strains from humans were examined for drug susceptibility and plasmid content. Four strains of swine origin and two strains of human origin harbored plasmid DNAs differing in molecular weights. No relationship between plasmid contents and drug resistance was observed. Southern DNA‐DNA hybridization showed that small plasmids from swine MAC strains were homologous to those from human origin at the nucleotide level.

Effects of the Beige Mutation on Respiratory Tract Infection with Pseudomonas aeruginosa in Mice

The role of neutrophil proteinases in the pathogenesis of respiratory tract infections with Pseudomonas aeruginosa was evaluated by studying the course of murine respiratory tract infection with a clinical isolate of P. aeruginosa mucoid strain developed by the agarose beads method in C57BL/6J(bg/bg) mice (beige mice). Neutrophils of beige mice are known to have defects in elastase and cathepsin G, but to have normal ability to produce reactive oxygen species. Contrary to the reported high susceptibility of beige mice to bacterial infections, we found that intratracheal inoculation of approximately 10(5) colony-forming units (CFU) of P. aeruginosa enmeshed in agarose beads resulted in lower mortality (0/16 versus 16/16, p < .01), fewer CFU counts in the lungs on day 5 (p < .05), and fewer elastolytic lung tissue injuries in beige mice compared with C57BL/6(+/+) mice. In vitro bactericidal study, however, revealed that beige neutrophils killed fewer bacteria than those of C57BL/6(+/+) mice (p < .05). Neutrophil elastase activities in the supernatants of pulmonary lavaged fluids measured using methoxysuccinyl-alanyl-alanyl-prolyl-valine-4-methylcoumar-7-amide were lower (p < .05) in beige mice than those in the normal littermates, whereas neutrophil recruitment into the airways and production of superoxide anion measured as the superoxide dismutase inhibitable rate of cytochrome c reduction were not impaired. These results suggest that neutrophil proteinases play a key role in tissue injuries in the respiratory tract infection with P. aeruginosa.