Animal model for cystic fibrosis: pulmonary clearance of Staphylococcus aureus in mice treated with reserpine.

Since it has been demonstrated that chronic administration of reserpine to rats produces CF-like alterations, we have studied the lung resistance to bacterial infections in animals treated with reserpine. Mice of the BALB/c inbred strain were injected subcutaneously with different doses of reserpine for 7 days; after, they were submitted to an infective aerosol containing $\text{Staphylococcus aureus}$ in a nebulization chamber. With each pair of exposed animals, an individual value of the uncleared bacteria ratio (UBR) at 4 hours was obtained. Reserpinized animals showed a significant increase in UBR values when compared to control mice (p < 0.05 and p < 0.01 depending on the doses), suggesting an impairment of the lung antibacterial defenses. Although pharmacological doses of reserpine produce catecholamine depletion, we can not conclude that this action upon the nervous system is the only cause of the CF-like response we detected. In conclusion, the observed UBR decrease lends support to the concept of a reserpine-induced CF animal model.     

Surfactant protein A mediates pulmonary clearance of Staphylococcus aureus

Surfactant protein A has been shown to enhance opsonization and clearance of Staphylococcus aureus in vitro. Here, the phagocytosis of alveolar S. aureus was investigated in vivo using intravital microscopy. Fluorescence labelled S. aureus Newman cells were intratracheally administered to anesthetized mice and the alveolar surface was observed for fifteen minutes. Confirming previously reported in vitro data, surfactant protein A-deficient mice showed a significantly reduced uptake of bacteria compared to wild-type mice.     

Generation of transducing particles in Staphylococcus aureus.

Transduction of plasmid pC194 and bacteriophage phi 11de varied inversely with the multiplicity of infection. As the multiplicity of infection decreased from 10(-1) to 10(-5) PFU/CFU, the transduction frequency of pC194 increased 10(4)-fold; the transduction frequency of phi 11de increased 300-fold with a 100-fold decrease in multiplicity of infection. Physical and genetic analysis of the transduced DNA showed that pC194 resided in the phage particle as a random, circularly permuted linear concatemer. In DNA prepared from phage that cotransduced pC194 and phi 11de, pC194 resided in the transducing phage primarily as a linear multimer of 15.8 kilobases, or about 5.4 pC194 monomers. The pC194 multimer was randomly inserted into the phi 11 genome.     

Effect of exercise on redistribution and clearance of inhaled particles from hamster lungs

Does exercise alter the redistribution and clearance of particles from the lungs? Sedentary hamsters and hamsters that were exercise trained by voluntary wheel running for the previous 5 wk were exposed to a 198Au-labeled aerosol for 25 min. Six trained and 6 sedentary animals were killed within 5 min after the exposure (day 0); the same number were killed 5 days later. The trained hamsters ran ad libitum during those 5 days. The lungs of all animals were excised, dried at total lung capacity, sliced into 1-mm-thick sections, and dissected into pieces that were counted for radioactivity and weighed. On day 0, trained hamsters had 80% more particles per milligram of lung than sedentary hamsters, although both were exposed under identical conditions of restraint. After five days, exercising hamsters cleared 38% of the particles present at day 0, whereas sedentary animals removed only 15%. Significant clearance was observed from the middle lung regions of sedentary hamsters and from all lung regions in exercising hamsters. We conclude that exercise can enhance the redistribution and clearance of particles from the lungs; the mechanisms responsible are as yet unclear.     

Influence of steroid aerosol treatments on the clearance of inhaled gold particles

Female Long Evans rats were used to test the hypothesis that inhaled triamcinolone acetonide accelerates the rate of clearance of particles from the lung. Three groups of animals inhaled a radioactive gold aerosol, which functioned as a tracer of respiratory tract clearance, and then were subjected to various inhalation treatments. The group treated with triamcinolone acetonide aerosol showed a significant acceleration in the rate of early clearance, but the total amount of tracer particles cleared in the first day was not significantly increased. Inhaled triamcinolone acetonide appears to accelerate the translocation of foriegn particles from small airways to larger ones, but stimulation of clearance does not appear to be a large effect.     

蜂胶酊对金黄色葡萄球菌性阴道炎疗效观察

目的探讨蜂胶酊对小鼠阴道内致病菌抑制及调理阴道菌群的作用。方法通过感染金黄色葡萄球菌建立小鼠阴道炎模型,用10％蜂胶酊冲洗治疗去除金黄色葡萄球菌在小鼠阴道的定植。倾注培养法（37℃,48h）计数阴道分泌物的细菌总数,镜下观察阴道黏膜炎症程度。结果蜂胶酊治疗组小鼠阴道内细菌的数量明显较对照组数量减少（P〈0．05）,治疗组黏膜炎症的治愈程度显著好于对照组。结论蜂胶酊对小鼠金黄色葡萄球菌性阴道炎有较好的治疗效果。     

Exacerbation of cigarette smoke-induced pulmonary inflammation by Staphylococcus aureus Enterotoxin B in mice

Background

Cigarette smoke (CS) is a major risk factor for the development of COPD. CS exposure is associated with an increased risk of bacterial colonization and respiratory tract infection, because of suppressed antibacterial activities of the immune system and delayed clearance of microbial agents from the lungs. Colonization with Staphylococcus aureus results in release of virulent enterotoxins, with superantigen activity which causes T cell activation.

Objective

To study the effect of Staphylococcus aureus enterotoxin B (SEB) on CS-induced inflammation, in a mouse model of COPD.

Methods

C57/Bl6 mice were exposed to CS or air for 4 weeks (5 cigarettes/exposure, 4x/day, 5 days/week). Endonasal SEB (10 μg/ml) or saline was concomitantly applied starting from week 3, on alternate days. 24 h after the last CS and SEB exposure, mice were sacrificed and bronchoalveolar lavage (BAL) fluid and lung tissue were collected.

Results

Combined exposure to CS and SEB resulted in a raised number of lymphocytes and neutrophils in BAL, as well as increased numbers of CD8⁺ T lymphocytes and granulocytes in lung tissue, compared to sole CS or SEB exposure. Moreover, concomitant CS/SEB exposure induced both IL-13 mRNA expression in lungs and goblet cell hyperplasia in the airway wall. In addition, combined CS/SEB exposure stimulated the formation of dense, organized aggregates of B- and T- lymphocytes in lungs, as well as significant higher CXCL-13 (protein, mRNA) and CCL19 (mRNA) levels in lungs.

Conclusions

Combined CS and SEB exposure aggravates CS-induced inflammation in mice, suggesting that Staphylococcus aureus could influence the pathogenesis of COPD.     

Determining deposition sites of inhaled lung particles and their effect on clearance

An essential component of lung defense is clearance of particulates and infectious vectors from the mucus membrane of the tracheobronchial tree and the alveolar regions of the lung. To partition clearance between these areas we determined the bronchial branching pattern, the anatomical sites of particle deposition, and subsequent clearance in the same animal. Using a 2.85-microns particle tagged with 57Co for inhalation and deposition in the sheep lung, we followed clearance via a series of computer-stored gamma-scintillation lung images. The same sheep was reinhaled, and the particle distributions for both inhalations were compared. After the animals were killed, the bronchial branching pattern and length of the bronchial tree were documented. The number of particles depositing in all bronchi down to 1 mm diam was determined by scintillation counting, and the number in respiratory bronchioles and alveoli was microscopically counted. We conclude that particles deposited in bronchi greater than or equal to 1 mm diam clear in 2-4 h postdeposition. Bronchi distal to 1-mm-diam bronchi and alveoli clear evenly over 72 h, and the number of particles equal to the tracheobronchial deposition cleared after 45 h.     

Effect of the cell components of Staphylococcus aureus on the functional activity of hemopoietic cells in mice

The data on the stimulating action of S. aureus cells, strains B-243, 2287, Wood-46, Cowan I, as well as cell-wall peptidoglycan, on the formation of endogenous colonies in the spleen of sublethally irradiated mice are presented. Teichoic acid, S. aureus ribosomal and cytoplasmic antigens produced no such effect. Whole S. aureus cells and their components were incapable of activating transitory colonies in the spleen of sublethally irradiated mice. After immunization with cell walls, peptidoglycan and protein A the mice showed a rise in the absolute and relative content of blood-forming stem cells in the marrow and the spleen. Killed S. aureus cells increased the relative content of blood-forming stem cells in the marrow, while in the spleen a rise in both absolute and relative content of such cells occurred, which was detected in the exocolonization test.     

Clumping of Staphylococcus aureus in the peritoneal cavity of mice

Kapral, Frank A. (Philadelphia General Hospital, Philadelphia, Pa.). Clumping of Staphylococcus aureus in the peritoneal cavity of mice. J. Bacteriol. 92:1188-1195. 1966.-Nonencapsulated strains of Staphylococcus aureus inoculated into the peritoneal cavity of mice are promptly clumped by the interaction of fibrinogen with the bound coagulase present on the bacterial surface. Some of the pre-existing leukocytes adhere to the staphylococcal clumps during the 1st hr, but phagocytosis is minimal. During the 2nd hr, there is an influx of neutrophils into the region, and these form a thick layer around the staphylococcal clumps and, apparently, prevent further egress of toxin. Leukocytes in proximity to the organisms undergo degeneration, but cells located externally maintain an effective barrier and, thus, confine the organisms. The encapsulated Smith strain of S. aureus is not clumped under these circumstances, presumably because the capsule prevents the bound coagulase-fibrinogen interaction.     

Photodynamic therapy for Staphylococcus aureus infected burn wounds in mice.

The rise of multiply antibiotic resistant bacteria has led to searches for novel antimicrobial therapies to treat infections. Photodynamic therapy (PDT) is a potential candidate; it uses the combination of a photosensitizer with visible light to produce reactive oxygen species that lead to cell death. We used PDT mediated by meso-mono-phenyl-tri(N-methyl-4-pyridyl)-porphyrin (PTMPP) to treat burn wounds in mice with established Staphylococcus aureus infections The third degree burn wounds were infected with bioluminescent S. aureus. PDT was applied after one day of bacterial growth by adding a 25% DMSO/500 microM PTMPP solution to the wound followed by illumination with red light and periodic imaging of the mice using a sensitive camera to detect the bioluminescence. More than 98% of the bacteria were eradicated after a light dose of 210 J cm(-2) in the presence of PTMPP. However, bacterial re-growth was observed. Light alone or PDT both delayed the wound healing. These data suggest that PDT has the potential to rapidly reduce the bacterial load in infected burns. The treatment needs to be optimized to reduce wound damage and prevent recurrence.