Female and male IL10–/– mice and IL10–/– mice lacking TLR4 (TLR4–/– × IL10–/–) (all in C57BL/10ScSn background) were bred and housed within the same specific pathogen-free unit of the Forschungseinrichtungen für Experimentelle Medizin (FEM, Charité – University Medicine Berlin). Immediately after weaning (i.e., at the age of 3 weeks), sex-matched mice of either genotype were subjected to a broad-spectrum antibiotic treatment as described earlier [13 (link), 20 (link)]. In brief, mice were transferred to sterile cages and treated with a quintuple antibiotic cocktail consisting of ampicillin plus sulbactam (1 g/l; Ratiopharm, Ulm, Germany), vancomycin (500 mg/l; Cell Pharm, Hannover, Germany), ciprofloxacin (200 mg/l; Bayer Vital, Leverkusen, Germany), imipenem (250 mg/l; MSD, Haar, Germany), and metronidazole (1 g/l; Fresenius, Bad Homburg, Germany) via the drinking water ad libitum for 4 months. Cultural and culture-independent (i.e., 16S rRNA based molecular) quality control measures revealed virtual absence of bacteria in fecal samples as described previously [13 (link), 21 (link)].