Epithelial hyperplasia and metaplasia are common features of inflammatory and neoplastic disease, but the basis for the altered epithelial phenotype is often uncertain. Here we show that long-term ciliated cell hyperplasia coincides with mucous (goblet) cell metaplasia after respiratory viral clearance in mouse airways. This chronic switch in epithelial behavior exhibits genetic susceptibility and depends on persistent activation of EGFR signaling to PI3K that prevents apoptosis of ciliated cells and on IL-13 signaling that promotes transdifferentiation of ciliated to goblet cells. Thus, EGFR blockade (using an irreversible EGFR kinase inhibitor designated EKB-569) prevents virus-induced increases in ciliated and goblet cells whereas IL-13 blockade (using s-IL-13Rα2-Fc) exacerbates ciliated cell hyperplasia but still inhibits goblet cell metaplasia. The distinct effects of EGFR and IL-13 inhibitors after viral reprogramming suggest that these combined therapeutic strategies may also correct epithelial architecture in the setting of airway inflammatory disorders characterized by a similar pattern of chronic EGFR activation, IL-13 expression, and ciliated-to-goblet cell metaplasia. IntroductionEpithelial cell hyperplasia and metaplasia are common consequences of inflammation and may be associated with protective as well as pathogenic outcomes. In the lung, airway epithelial remodeling can be life threatening, since mucous cell metaplasia is the foundation for hypersecretion that can obstruct the airway lumen. Despite the critical nature of this process, little is known about how mucous cell metaplasia develops in the setting of acute or chronic inflammatory disease. Particularly, little is known about the mechanism for what is likely the most common cause of mucous cell metaplasia in the lung, i.e., respiratory viral infection, since previous work has focused on bacterial, allergic, and carcinogenic stimuli. Perhaps because of the paucity of mechanistic information, no effective and specific pharmacologic treatment is currently available to treat epithelial cell metaplasia in general or mucous cell metaplasia in particular.In this context, recent work on mucous cell metaplasia has often focused on signaling pathways initiated by activation of the IL-13 receptor (IL-13R) and EGFR (also designated ErbB1 and HER1). The experimental role of IL-13R was established when a decoy receptor for IL-13 (soluble IL-13Rα2-Fc) was found to inhibit allergen-induced mucous (goblet) cell formation in mice (1, 2). These reports have been followed by evidence that IL-13 can directly drive mucin gene expression in airway epithelial cells cultured under physiologic conditions and in vivo (3-6). Moreover, IL-13 is often overexpressed in the setting of mucous cell metaplasia in asthma

Forkhead transcription factors play key roles in the regulation of immune responses. Here, we identify a role for one member of this family, Foxj1, in the regulation of T cell activation and autoreactivity. Foxj1 deficiency resulted in multiorgan systemic inflammation, exaggerated Th1 cytokine production, and T cell proliferation in autologous mixed lymphocyte reactions. Foxj1 suppressed NF-kappaB transcription activity in vitro, and Foxj1-deficient T cells possessed increased NF-kappaB activity in vivo, correlating with the ability of Foxj1 to regulate IkappaB proteins, particularly IkappaBbeta. Thus, Foxj1 likely modulates inflammatory reactions and prevents autoimmunity by antagonizing proinflammatory transcriptional activities. These results suggest a potentially general role for forkhead genes in the enforcement of lymphocyte quiescence.

Establishment and maintenance of epithelial cell polarity depend on cytoskeletal organization and protein trafficking to polarized cortical membranes. ERM (ezrin, radixin, moesin) family members link polarized proteins with cytoskeletal actin. Although ERMs are often considered to be functionally similar, we found that, in airway epithelial cells, apical localization of ERMs depend on cell differentiation and is independently regulated. Moesin was present in the apical membrane of all undifferentiated epithelial cells. However, in differentiated cells, ezrin and moesin were selectively localized to apical membranes of ciliated airway cells and were absent from secretory cells. To identify regulatory proteins required for selective ERM trafficking, we evaluated airway epithelial cells lacking Foxj1, an F-box factor that directs programs required for cilia formation at the apical membrane. Interestingly, Foxj1 expression was also required for localization of apical ezrin, but not moesin. Additionally, membrane-cytoskeletal and threonine-phosphorylated ezrin were decreased in Foxj1-null cells, consistent with absent apical ezrin. Although apical moesin expression was present in null cells, it could not compensate for ezrin because ERM-associated EBP50 and the β2 adrenergic receptor failed to localize apically in the absence of Foxj1. These findings indicate that Foxj1 regulates ERM proteins differentially to selectively direct the apical localization of ezrin for the organization of multi-protein complexes in apical membranes of airway epithelial cells.

Age-and gender-related lymphoid tissue variability in control male and female monkeys of various ages (under three years; three to six years; seven to fifteen years) was characterized. Spleen and thymus organ weights, organ-to-body and organ-to-brain ratios, morphology by light microscopy, and B-and T-cell immunohistochemistry (IHC) were evaluated. Splenic weights and ratios were not significantly different between various age groups or genders, except males and females in the three-to-six-years age group, who exhibited statistically significant changes from the under-three-years age group. No differences in the number of primary follicles, secondary follicles with germinal centers, B-cell follicles, and periarterial lymphoid sheath were seen between age groups or genders, and no trends were noted in the spleen. By IHC, no differences were observed in B-and T-cell splenic densities. Several age-and gender-related changes in weights and ratios were noted in the thymus. The thymus had a trend toward increased interlobular fat infiltration with increasing age in both males and females. Thymic delineation of the cortex and medulla was significantly decreased in the seven-to-fifteen-years age group for males only. The cortex-to-medulla ratio was significantly lower only in males in the seven-to-fifteen-years age group. B-and T-cell cellular density did not change across various ages.

Alteration in fixation time using Diff-Quik does not improve staining characteristics of mast cell tumors.