Obesity is accompanied by low-grade chronic systemic infl ammation characterized by increased circulating levels of proinfl ammatory cytokines, including interleukin (IL)-1  , tumor necrosis factor (TNF)-␣ , and IL-6 ( 1 ). Activation of infl ammatory pathways induces metabolic disturbances, leading to insulin resistance, dyslipidemia, and cardiovascular diseases. Caspase-1 is a cysteine protease that is known for its crucial role in the activation of the proinfl ammatory cytokines IL-18 and IL-1  . Additionally, caspase-1 has been shown to cleave other substrates, including proteins involved in energy metabolism ( 2-4 ). Caspase-1 activation is controlled by the infl ammasome, a multiprotein Abstract Caspase-1 is known to activate the proinfl ammatory cytokines IL-1  and IL-18. Additionally, it can cleave other substrates, including proteins involved in metabolism. Recently, we showed that caspase-1 defi ciency in mice strongly reduces high-fat diet-induced weight gain, at least partly caused by an increased energy production. Increased feces secretion by caspase-1-defi cient mice suggests that lipid malabsorption possibly further reduces adipose tissue mass. In this study we investigated whether caspase-1 plays a role in triglyceride-(TG)-rich lipoprotein metabolism using caspase-1-defi cient and wild-type mice. Caspase-1 defi ciency reduced the postprandial TG response to an oral lipid load, whereas TG-derived fatty acid (FA) uptake by peripheral tissues was not affected, demonstrated by unaltered kinetics of [
Lipid composition of fecesMice were individually housed for 4 days to determine food intake and collect feces quantitatively. Feces were weighed, freeze-dried, and ground, and fecal fatty acids (FA) were derivatized by methyl esterifi cation. Therefore, 2 ml methanol/hexane (4:1 v/v) containing 80 µg pentadecanoic acid (C15:0) as an internal standard (Fluka) was added to 15 mg of feces. Then, 200 µL acetyl chloride (Merck) was added, and samples were incubated at 95°C. After cooling to 4°C, 5 ml 6% K 2 CO 3 (Sigma) was added, and samples were centrifuged (10 min; 4,000 rpm, 4°C). The upper hexane layer was isolated and used for GC analysis of FA methyl esters (FAME). FAME were separated on a 50 m × 0.25 mm capillary GC column (CP Sil 88; Agilent technologies) in a 3800 GC gas chromatograph (Varian) equipped with a fl ame ionization detector. The injector and fl ame ionization detector were kept at 270°C. The column temperature was programmed from 170°C to 210°C. FAME were introduced by split injection (split ratio 20:1). Quantifi cation was based on the area ratio of the individual FA to the internal standard.To extract total cholesterol from feces, dried feces (10 mg) were incubated in 1 ml alkaline methanol (CH 3 OH: 1 M NaOH = 3:1 [v/v]) for 2 h at 80°C in screw-capped tubes using 5 ␣ -cholestane as internal standard. Tubes were cooled to room temperature, and the cholesterol was extracted twice with 2 ml petroleum ether. The combined petroleum ether layers were evaporated to dryness, and the ...