Studies performed to identify early events of ovarian cancer and to establish molecular markers to support of early detection and the development of chemopreventive regimens have been hindered by a lack of adequate cell models. Taking advantage of the spontaneous transformation of mouse ovarian surface epithelial (MOSE) cells in culture, we isolated and characterized distinct transitional stages of ovarian cancer as the cells progressed from a premalignant nontumorigenic phenotype to a highly aggressive malignant phenotype. Transitional stages were concurrent with progressive increases in proliferation, anchorage-independent growth capacity, in vivo tumor formation, and aneuploidy. During neoplastic progression, our ovarian cancer model underwent distinct remodeling of the actin cytoskeleton and focal adhesion complexes, concomitant with downregulation and/or aberrant subcellular localization of two tumor-suppressor proteins E-cadherin and connexin-43. In addition, we demonstrate that epigenetic silencing of E-cadherin through promoter methylation is associated with neoplastic progression of our ovarian cancer model. These results establish critical interactions between cellular cytoskeletal remodeling and epigenetic silencing events in the progression of ovarian cancer. Thus, our MOSE model provides an excellent tool to identify both cellular and molecular changes in the early and late stages of ovarian cancer, to evaluate their regulation, and to determine their significance in an immunocompetent in vivo environment.

Previous studies have demonstrated that animals exposed to Streptococcus pneumoniae while recovering from influenza A virus infection exhibit exacerbated disease symptoms. However, many of the current animal models exploring dual viral and bacterial synergistic exacerbations of respiratory disease have utilized mouse-adapted influenza virus and strains of Streptococcus pneumoniae that in themselves are highly lethal to mice. Here we describe a mouse model of bacterial superinfection in which a mild, self-limiting influenza virus infection is followed by mild, self-limiting superinfection with S. pneumoniae serotype 3. S. pneumoniae superinfection results in rapid dissemination of the bacterium from the respiratory tract and systemic spread to all major organs of the mice, resulting in fatal septicemia. This phenomenon in mice was observed in superinfected animals undergoing an active viral infection as well as in mice that had completely cleared the virus 7 to 8 days prior to superinfection. Neutrophils were the predominant cellular inflammatory infiltrate in the lungs of superinfected mice compared to singly infected animals. Among other cytokines and chemokines, the neutrophil activator granulocyte colony-stimulating factor (G-CSF) was found to be significantly overexpressed in the spleens, lungs, and brains of superinfected animals. High G-CSF protein levels were observed in sera and lung lavage fluid from superinfected animals, suggesting that G-CSF is a major contributor to synergistic exacerbation of disease leading to fatal septicemia.

A high percentage of asthma is associated with aeroallergen exposures. Glucocorticoids such as methylprednisolone represent a major method for managing chronic asthma. However, studies suggested that corticosteroid therapy might have the potential to stimulate rather than inhibit adaptive immune inflammatory reactions, raising concerns about possible adverse reactions due to excessive repeated methylprednisolone treatment. Therefore, a murine model of allergen-induced inflammation was characterized and used to investigate the effects of repeated intraperitoneal (ip) and transnasal treatments with methylprednisolone (0-20 mg/kg body weight) and cyclosporin A (20 mg/kg body weight). Sensitized BALB/c female mice were exposed daily to ovalbumin (OVA) aerosols for up to 5 d with 24-h postexposure analyses for airway responses to methacholine aerosols and inflammatory cell recoveries by bronchoalveolar lavage (BAL) and tissue collagenase dispersion. Although increased tissue neutrophils, lymphocytes, monocytes, and macrophages reached maximal levels after 2 daily OVA exposures, recoverable eosinophil numbers continued to rise over the 5-d period. Daily ip treatments with a 5-mg/kg body weight dose of methylprednisolone diminished both OVA-induced airway responses to methacholine and inflammatory-cell accumulations to levels comparable to those observed with cyclosporin A. However, treatments with higher doses of methylprednisolone reversed this anti-inflammatory effect, indicated by a return to untreated levels of OVA-induced eosinophil recovery. A similar biphasic response in eosinophil recoveries was observed using daily transnasal methylprednisolone treatments that correlated with a concomitant fall and rise in BAL interleukin-13. These results supported the hypothesis that repeated high-steroid treatments might activate rather than suppress allergen-induced immune responses.

Exposure to aerosols generated from water-soluble metal-working fluids (MWF) is associated with numerous respiratory symptoms consistent with an acute pulmonary inflammatory event. Previous studies in mice and guinea pigs have implicated endotoxin contamination of MWF as the causative agent responsible for inducing pulmonary neutrophilia and decrements in airway conductance. However, little information is known about the relationship between endotoxin-contaminated MWF exposure and changes in airway physiology. The present study, utilizing a rat model, has demonstrated that exposure to 10 mg/m3 with endotoxin (0 to 3.2 micrograms/m3) resulted in a time- and concentration-dependent migration of neutrophils in the lung tissue's interstitial spaces as well as the lavageable airways. In contrast to other airborne toxicants, where neutrophil infiltration of the lung has been associated with hyperresponsive airways, the endotoxin-induced neutrophilia observed in the present study was not associated with airway hyperresponsiveness to challenge with the muscarinic agent methacholine or with permeability damage to the lung. Bronchoalveolar lavage (BAL)-recovered neutrophils demonstrated no adverse effects as a result of endotoxin-contaminated MWF exposure. In contrast, a population of alveolar macrophages was observed to be enlarged in size and demonstrated an increased sensitivity to oxidative metabolism when challenged with phorbol myristate acetate, consistent with being at a relatively high state of activation. These results suggest that while endotoxin contamination of MWF is capable of producing an acute inflammatory event, other predisposition factors may be required to induce alterations in pulmonary physiology.

This study detailed the sequence of recurring inflammatory events associated with episodic allergen exposures of mice resulting in airway hyperreactivity, sustained inflammation, goblet cell hyperplasia, and fibrogenesis that characterize a lung with chronic asthma. Ovalbumin (OVA)-sensitized female Balb/c mice were exposed to saline-control or OVA aerosols for 1hr per day for episodes of 3 days every week for up to 8 weeks. Lung inflammation was assessed by inflammatory cell recoveries using bronchoalveolar lavages (BAL) and tissue collagenase dispersions. Cell accumulations were observed within airway submucosal and associated perivascular spaces using immunohistochemical and tinctorial staining methods. Airway responsiveness to methacholine aerosols were elevated after 2 weeks and further enhanced to a sustained level after the 4th and 8th weeks. Although by the 8th week, diminished OVA-induced accumulations of eosinophils, neutrophils and monocyte-macrophages were observed, suggesting diminished responsiveness, the BAL recovery of lymphocytes remained elevated. Airway but not perivascular lesions persisted with a proliferating cell population, epithelial goblet cell hyperplasia and evidence of enhanced collagen deposition. Examination of lung inflammatory cell content before the onset of the 1st, 2nd and 4th OVA exposure episodes demonstrated enhancements in residual BAL lymphocyte and BAL and tissue eosinophil recoveries with each exposure episode. Although tissue monocyte-macrophage numbers returned to baseline prior to each exposure episode, the greatest level of accumulation was observed after the 4th week. These results provide the basis for establishing the inflammatory and exposure criteria by which episodic environmental exposures to allergen might result in the development of a remodeled lung in asthma.