Antibiotics damage the colonic mucus barrier in a microbiota-independent manner.

Antibiotic use is a risk factor for development of inflammatory bowel diseases (IBDs). IBDs are characterized by a damaged mucus layer, which does not separate the intestinal epithelium from the microbiota. Here, we hypothesized that antibiotics affect the integrity of the mucus barrier, which allows bacterial penetrance and predisposes to intestinal inflammation.

Salmonella manipulates the host to drive pathogenicity via induction of interleukin 1β.

Acute gastrointestinal infection with intracellular pathogens like Salmonella Typhimurium triggers the release of the proinflammatory cytokine interleukin 1β (IL-1β). However, the role of IL-1β in intestinal defense against Salmonella remains unclear. Here, we show that IL-1β production is detrimental during Salmonella infection.

Autophagy controls mucus secretion from intestinal goblet cells by alleviating ER stress.

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.

Hair-Follicle Mesenchymal Stem Cell Activity during Homeostasis and Wound Healing.

The mesenchymal components of the hair follicle-the dermal papilla (DP) and dermal sheath (DS)-are maintained by hair follicle dermal stem cells, but the position of this stem cell population throughout the hair cycle, its contribution to the maintenance of the dermis, and the existence of a migratory axis from the DP to the dermis remain unclear. In this study, we show that during homeostasis DP and DS cells are confined to their compartments, and during the regression phase of the hair cycle, some DP/DS cells undergo apoptosis and subsequently are internalized by nearby adipocytes. In contrast, during wound healing, DP/DS cells move toward the wound but do not directly participate in follicle neogenesis.

Fgf and Wnt signaling interaction in the mesenchymal niche regulates the murine hair cycle clock.

Tissue growth in the adult is an orchestrated process that often requires biological clocks to time stem cell and progenitor activity. Here, we employed the hair follicle, which cycles between growth and regression in a timely-restricted mode, to show that some components of the hair cycle clock reside within the mesenchymal niche of the hair follicle, the dermal papilla (DP), and both Fgf and Wnt signaling pathways interact within the DP to regulate the expression of these components that include Wnt agonists (Rspondins) and antagonists (Dkk2 and Notum). The levels of Wnt agonists and antagonists in the DP are progressively reduced and elevated during the growth phase, respectively.