Background & Aims When the glial fibrillary acidic protein (GFAP) promoter is used to express cellular toxins that eliminate glia in mice, intestinal epithelial permeability and proliferation increase; this led to the concept that glia are required for maintenance of the gastrointestinal epithelium. Many enteric glia, however, particularly in the mucosa, do not express GFAP. In contrast, virtually all enteric glia express proteolipid protein 1 (PLP1). We investigated whether elimination of PLP1-expressing cells compromises epithelial maintenance or gastrointestinal motility. Methods We generated mice that express tamoxifen-inducible Cre recombinase under control of the Plp1 promoter and carry the diptheria toxin subunit A (DTA) transgene in the Rosa26 locus (Plp1CreER;Rosa26DTA mice). In these mice, PLP1-expressing glia are selectively eliminated without affecting neighboring cells. We measured epithelial barrier function and gastrointestinal motility in these mice and littermate controls, and analyzed epithelial cell proliferation and ultrastructure from their intestinal tissues. To compare our findings with those from previous studies, we also eliminated glia with ganciclovir in GfapHSV-TK mice. Results Expression of DTA in PLP1-expressing cells selectively eliminated enteric glia from the small and large intestines, but caused no defects in epithelial proliferation, barrier integrity, or ultrastructure. In contrast, administration of ganciclovir to GfapHSV-TK mice eliminated fewer glia but caused considerable non-glial toxicity and epithelial cell death. Elimination of PLP1-expressing cells did not reduce survival of neurons in the intestine, but altered gastrointestinal motility in female, but not male, mice. Conclusions Using the Plp1 promoter to selectively eliminate glia in mice, we found that enteric glia are not required for maintenance of the intestinal epithelium but are required for regulation of intestinal motility in females. Previous observations supporting the concept that maintenance of the intestinal epithelium requires enteric glia can be attributed to non-glial toxicity in GfapHSV-TK mice and epithelial-cell expression of GFAP. Contrary to widespread notions, enteric glia are therefore not required for epithelial homeostasis. However, they regulate intestinal motility in a sex-dependent manner.

Highlights d Treg cells in the colon lamina propria reside close to neuron projections d Neurons modulate the differentiation and phenotype of iTreg cells in culture via IL-6 d Neuron-specific ablation of Il6 increases the number of RORg + Treg cells in vivo d Microbial colonization affects a subset of neurons in the enteric nervous system

Summary Kawasaki disease (KD) is the leading cause of acquired heart disease in children. In addition to coronary artery abnormalities, aneurysms and myocarditis, acute KD is also associated with echocardiogram (ECG) abnormalities in 40–80% of patients. Here, we show that these ECG changes are recapitulated in the Lactobacillus casei cell wall extract (LCWE)‐induced KD vasculitis mouse model. LCWE‐injected mice developed elevated heart rate and decreased R wave amplitude, with significant differences in prolonged ventricular repolarization. LCWE‐injected mice developed cardiac ganglion inflammation, that may affect the impulse‐conducting system in the myocardium. Furthermore, serum nerve growth factor (NGF) was significantly elevated in LCWE‐injected mice, similar to children with KD vasculitis, associated with increased neural remodeling of the myocardium. ECG abnormalities were prevented by blocking interleukin (IL)‐1 signaling with anakinra, and the increase in serum NGF and cardiac neural remodeling were similarly blocked in Il1r1−/− mice and in wild‐type mice treated with anakinra. Thus, similar to clinical KD, the LCWE‐induced KD vasculitis mouse model also exhibits electrophysiological abnormalities and cardiac neuronal remodeling, and these changes can be prevented by blocking IL‐1 signaling. These data support the acceleration of anti‐IL‐1 therapy trials to benefit KD patients.

No abstract