Project description:Colonic goblet cells are specialized epithelial cells that secrete mucus to physically separate the host and its microbiota, thus preventing bacterial invasion and inflammation. How goblet cells control the amount of mucus they secrete is unclear. We found that constitutive activation of autophagy in mice via Beclin 1 enables the production of a thicker and less penetrable mucus layer by reducing endoplasmic reticulum (ER) stress. Accordingly, genetically inhibiting Beclin 1-induced autophagy impairs mucus secretion, while pharmacologically alleviating ER stress results in excessive mucus production. This ER-stress-mediated regulation of mucus secretion is microbiota dependent and requires the Crohn's-disease-risk gene Nod2. Overproduction of mucus alters the gut microbiome, specifically expanding mucus-utilizing bacteria, such as Akkermansia muciniphila, and protects against chemical and microbial-driven intestinal inflammation. Thus, ER stress is a cell-intrinsic switch that limits mucus secretion, whereas autophagy maintains intestinal homeostasis by relieving ER stress.
Project description:Colonic goblet cells respond to invading enteropathogens by secreting Muc2 mucin and other specific goblet cell proteins that physically entrap and expel microbes away from the epithelium. At present, it is unclear how innate effectors in the gut, including small cationic cathelicidin peptides secreted by the intestinal epithelium and leukocytes, contribute to mucus barrier defense during infections. In this study, we used cathelicidin-deficient (Camp-/-) mice, colonoids, and human colonic LS174T goblet cells to elucidate the mechanisms by which cathelicidin regulates goblet cell secretions in innate host defense against attaching/effacing Citrobacter rodentium. We showed that even though Camp-/- littermates infected with C. rodentium displayed increased fecal shedding and epithelial colonization, Muc2 mucin granules were retained in bloated colonic goblet cells that impaired mucus secretion and expressed less mucus-associated proteins, as quantified by proteomic analysis. C. rodentium infected Camp-/- littermates showed impaired reactive oxygen species (ROS) production and transcriptomic profiling associated with decreased ROS biosynthesis and an increase in ROS negative regulators. Camp-/- bone marrow derived macrophages produced less ROS than their wild-type counterparts. In LS174T goblet cells, human cathelicidin LL-37 promptly induced the secretion of goblet cell-associated TFF3 and RELMβ, which was dependent on ROS production. These findings demonstrate that cathelicidin signaling in colonic goblet cells regulates mucus and mucin-associated protein secretion via an ROS-dependent mechanism to clear bacterial infections and restore gut homeostasis.
Project description:To determine how constitutively active autophagy in Becn1F121A mice affects the colonic tissue, we performed a transcriptional analysis.
Project description:High numbers of goblet cells in airways contribute to the mucus obstruction characteristic of asthmatic airways. Allergen challenged mice exhibit robust expression of goblet cells within airway surface epithelium. This study looks at the temporal analysis of IL-13 exposed murine airways to elucidate pathways that result in differentiation of airway epithelial cells to goblet cells.
Project description:High numbers of goblet cells in airways contribute to the mucus obstruction characteristic of asthmatic airways. Allergen challenged mice exhibit robust expression of goblet cells within airway surface epithelium. This study looks at the temporal analysis of IL-13 exposed murine airways to elucidate pathways that result in differentiation of airway epithelial cells to goblet cells. Keywords: other
Project description:Exposure to particulate matter (PM) in ambient air is known to increase the risk of cardiovascular disorders and mortality. The cytotoxicity of PM is mainly due to the abnormal increase of reactive oxygen species (ROS), which damage cellular components such as DNA, RNA, and proteins. The correlation between PM exposure and human disorders, including mortality, is based on long-term exposure. In this study we have investigated acute responses of mucus-secreting goblet cells upon exposure to PM derived from a heavy diesel engine. To this end, we employed the mucociliary epithelium of amphibian embryos and human Calu-3 cells to examine PM mucotoxicity. Our data suggest that acute exposure to PM significantly impairs mucus secretion and results in the accumulation of mucus vesicles in the cytoplasm of goblet cells. RNA-seq analysis revealed that acute responses to PM exposure significantly altered gene expression patterns; however, known regulators of mucus production and the secretory pathway were not significantly altered. Interestingly, pretreatment with α-tocopherol nearly recovered the hyposecretion of mucus from both amphibian and human goblet cells. We believe this study demonstrates the mucotoxicity of PM and the protective function of α-tocopherol on mucotoxicity caused by acute PM exposure from heavy diesel engines.