Urease and Helicobacter spp. antigens in pulmonary granuloma

Pulmonary sarcoidosis, a human disease of unknown cause, has no animal model. Sarcoidosis patients have serum antibodies specific for Helicobacter pylori and its surface enzyme urease. H. pylori do not survive in the high-oxygen pulmonary atmosphere, but urease may access the lung by oesophageal reflux. A model was established in rats to study gastro-oesophageal reflux of urease into the airways. Pathology in tissues from human sarcoidosis patients was compared with that in the rat model. Changes observed in the rat model included prominent peribronchial lymphocytic infiltration, which is seen occasionally in human sarcoidosis. Granulomas, pathognomonic for human sarcoidosis, occurred occasionally in the lungs of rats given urease protein intratracheally, but were widespread when urease was coupled to microbeads and administered intravenously. Biomarkers associated with human sarcoidosis (interleukin1-β and platelet-activating factor) were up-regulated acutely in the rat model. Further investigations with this model may provide significant insights into the origin and pathogenesis of pulmonary diseases in man and other species that carry gastric Helicobacter spp. and its associated enzyme.

Dissecting the link between nanoparticle lung effects and tumor markers with CD24 measurements

e21085

Background: It was postulated that carbon nanoparticles (CN) induced mesothelioma-like changes equal to asbestos in mice. We investigated CN added to human mesothelial cells in culture and reported that CN-induced cell damage to untransformed human mesothelial cells is rapidly followed by secretion of tumor markers like mesothelin and osteopontin. In vivo in animals, our group quantifies CN lung damage by HMGB1, an intranuclear protein released into alveolar lavage after CN exposure. Recent work suggests that the cell surface marker CD24 associates with HMGB1 to blunt lung responses to damage (like CN), but does not blunt cell response to pathogen-released HMGB1. Since CD24 is also a known cancer marker, elevated in many malignancies, we hypothesized that the cellular change elicited by CD24 when coupled with a damage marker would offer a mechanism through which CN could produce –repeated over time—malignant change in exposed human mesothelial cells. Such expression would support our previous research efforts. Methods: Untransformed human mesothelial cells were cultured and then stimulated or not with a CN dose giving 80% cell viability. At 24, 48 & 72 hr cells were fixed and stained with anti-CD 24. Presence of positive stain was photographed and counted. CN exposed and control rat lungs were harvested and frozen at 0.5 hr, 3 hr, 24 hr and 4 weeks. Western blot and immunostaining (with Anti-CD24 antibody and mucin chemical stain) was used to measure CD24 levels. Results: In CN-exposed animals, CD24 was highest at 24 hr. Mucin presence confirms the CD24 staining. Homogenates by Western blot also showed highest CD24 reactivity at 24 hr. In CN-exposed cultured cells, at 48 hr, some anti-CD24 staining was seen and at 72 hr in clusters of hyperproliferating cells, strong CD24 stain was seen. Conclusions: Our data suggest, as shown by a second cellular marker CD24, that the mesothelin upregulation seen in our previous studies indicated a cellular change beyond necrosis. Nanoparticles at a dose producing 20% cell death induce this change in healthy human mesothelial cells in culture.

Fat embolism: evolution of histopathological changes in the rat lung

The pathophysiology of Fat Embolism Syndrome (FES) is poorly understood and subject to some controversy. Evaluation of the evolution of histological changes in the lungs of patients with FES is impractical. The current theories of FES were established through acute clinical observations and acute animal experiments, but sequential changes in the histology of lungs over a prolonged period have not been made. The progressive effects of fat embolization of the lungs were examined in a rat model over a period of 11 days. Triolein, a major bone marrow fat, was administered to conscious Sprague-Dawley rats via the caudal vein. Rats were euthanized at 24, 48, 96 h, and 11 days, but some died within a few hours. Histomorphometric evaluations of lung tissue were made, including stains for fat, collagen, and smooth muscle actin. Arterial and arteriolar patency decreased progressively up to 96 h, but returned toward normal after 11 days. A striking finding was the very early presence of inflammation and fibrosis after only several hours, persisting up to 11 days. The results of this study provide evidence of both very early and prolonged changes due to fat embolization.

Biochemical and histological effects of exendin-4 (exenatide) on the rat pancreas

AIMS/HYPOTHESIS

Exendin-4 is a 39 amino acid agonist of the glucagon-like peptide receptor and has been approved for treatment of type 2 diabetes. Many reports describe an increased incidence of acute pancreatitis in humans treated with exendin-4 (exenatide). Previous studies have evaluated the effect of exendin-4 on beta cells and beta cell function. We evaluated the histological and biochemical effects of exendin-4 on the pancreas in rats.

METHODS

We studied 20 Sprague-Dawley male rats, ten of which were treated with exendin-4 and ten of which were used as controls. The study period was 75 days. Serum and pancreatic tissue were removed for biochemical and histological study. Blood glucose, amylase, lipase, insulin and adipocytokines were compared between the two groups.

RESULTS

Animals treated with exendin-4 had more pancreatic acinar inflammation, more pyknotic nuclei and weighed significantly less than control rats. They also had higher serum lipase than control animals. Exendin-4 treatment was associated with lower insulin and leptin levels as well as lower HOMA values than in the untreated control group.

CONCLUSIONS/INTERPRETATION

Although the use of exendin-4 in rats is associated with decreased weight gain, lower insulin resistance and lower leptin levels than in control animals, extended use of exendin-4 in rats leads to pancreatic acinar inflammation and pyknosis. This raises important concerns about the likelihood of inducing acute pancreatitis in humans receiving incretin mimetic therapy.