L fructose

Compounds DHAP, DHA, l-GAL, AP from potato, isopropyl-β-d-thiogalactopyranoside (IPTG), polyphosphate, ATP, l-fructose, l-tagatose, glycerol, glucose, and antibiotics were purchased from Sigma-Aldrich. All restriction enzymes and DNA ligase were purchased from Novagen (Darmstadt, Germany). Ni–NTA affinity chromatography column was purchased from QIAGEN. The yeast extract and tryptone were purchased from OXOID LID, and brain heart infusion (BHI) was purchased from Becton, Dickinson and Company. All bacterial strains and plasmids are listed in Table 4.

C57BL/6J six-week-old male mice from Envigo RMS, Srl.(Indianapolis, IN, United States) were housed in collective cages at 22°C ± 1 °C under a 12 h light/dark cycle and with food and water provided ad libitum. After a 1-week acclimatization, animals were randomly divided into 3 groups as reported in the experimental scheme in Figure 1. High-fat diet (18% kcal protein, 24% kcal carbohydrate, 58% kcal fat for a total of 5.6 kcal/g) was provided by Laboratory Dottori Piccioni, Milan, Italy). High sugar (23.1 g L-fructose plus 18.9 g L-glucose/L) (Sigma-Aldrich, St. Louis, MO, USA) was added to tap water; the cyclic administration of 1% (w/v) DSS (molecular mass, 36,000–50,000 Da, MP Biomedicals, Santa Ana, CA, USA) was also added in drinking water. After 13 weeks, animals were weighed and euthanized, brains were removed for immunohistochemistry and immunofluorescence, and serum samples were stored at −80 °C for biochemical analysis.