CE exerts beneficial metabolic effects through improving HFHS diet-induced features of the metabolic syndrome, which is associated with a proportional increase in Akkermansia spp.

No abstract

Cranberry fruit has been reported to have high antioxidant effectiveness that is potentially linked to its richness in diversified polyphenolic content. The aim of the present study was to determine the role of cranberry polyphenolic fractions in oxidative stress (OxS), inflammation and mitochondrial functions using intestinal Caco-2/15 cells. The combination of HPLC and UltraPerformance LC®-tandem quadrupole (UPLC-TQD) techniques allowed us to characterize the profile of low, medium and high molecular mass polyphenolic compounds in cranberry extracts. The medium molecular mass fraction was enriched with flavonoids and procyanidin dimers whereas procyanidin oligomers (DP > 4) were the dominant class of polyphenols in the high molecular mass fraction. Pre-incubation of Caco-2/15 cells with these cranberry extracts prevented iron/ascorbate-mediated lipid peroxidation and counteracted lipopolysaccharide-mediated inflammation as evidenced by the decrease in pro-inflammatory cytokines (TNF-α and interleukin-6), cyclo-oxygenase-2 and prostaglandin E2. Cranberry polyphenols (CP) fractions limited both nuclear factor κB activation and Nrf2 down-regulation. Consistently, cranberry procyanidins alleviated OxS-dependent mitochondrial dysfunctions as shown by the rise in ATP production and the up-regulation of Bcl-2, as well as the decline of protein expression of cytochrome c and apoptotic-inducing factor. These mitochondrial effects were associated with a significant stimulation of peroxisome-proliferator-activated receptor γ co-activator-1-α, a central inducing factor of mitochondrial biogenesis and transcriptional co-activator of numerous downstream mediators. Finally, cranberry procyanidins forestalled the effect of iron/ascorbate on the protein expression of mitochondrial transcription factors (mtTFA, mtTFB1, mtTFB2). Our findings provide evidence for the capacity of CP to reduce intestinal OxS and inflammation while improving mitochondrial dysfunction.

Since gastrointestinal mucosa is constantly exposed to reactive oxygen species from various sources, the presence of antioxidants may contribute to the body’s natural defenses against inflammatory diseases.HypothesisTo define the polyphenols extracted from dried apple peels (DAPP) and determine their antioxidant and anti-inflammatory potential in the intestine. Caco-2/15 cells were used to study the role of DAPP preventive actions against oxidative stress (OxS) and inflammation induced by iron-ascorbate (Fe/Asc) and lipopolysaccharide (LPS), respectively.ResultsThe combination of HPLC with fluorescence detection, HPLC-ESI-MS TOF and UPLC-ESI-MS/MS QQQ allowed us to characterize the phenolic compounds present in the DAPP (phenolic acids, flavonol glycosides, flavan-3-ols, procyanidins). The addition of Fe/Asc to Caco-2/15 cells induced OxS as demonstrated by the rise in malondialdehyde, depletion of n-3 polyunsaturated fatty acids, and alterations in the activity of endogenous antioxidants (SOD, GPx, G-Red). However, preincubation with DAPP prevented Fe/Asc-mediated lipid peroxidation and counteracted LPS-mediated inflammation as evidenced by the down-regulation of cytokines (TNF-α and IL-6), and prostaglandin E2. The mechanisms of action triggered by DAPP induced also a down-regulation of cyclooxygenase-2 and nuclear factor-κB, respectively. These actions were accompanied by the induction of Nrf2 (orchestrating cellular antioxidant defenses and maintaining redox homeostasis), and PGC-1α (the “master controller” of mitochondrial biogenesis).ConclusionOur findings provide evidence of the capacity of DAPP to reduce OxS and inflammation, two pivotal processes involved in inflammatory bowel diseases.

Short-chain fatty acids (SCFAs) are potent modulators of the growth, function, and differentiation of intestinal epithelia. In addition, high-fiber diets may protect against the development of atherosclerosis because of their cholesterol-lowering effects due, in large part, to SCFA production, liver sterol metabolism, and bile acid excretion. Although the small gut plays a major role in dietary fat transport and contributes substantially to plasma cholesterol and lipoprotein homeostasis, the impact of SCFAs on intestinal lipid handling remains unknown. In the present study, the modulation of lipid synthesis, apolipoprotein biogenesis, and lipoprotein secretion by butyrate was investigated in Caco-2 cells plated on permeable polycarbonate filters, which permit separate access to the upper and lower compartments of the monolayers. Highly differentiated and polarized cells (20 days of culture) were incubated for 20 h with 20 mM butyrate in the apical medium. In the presence of [14C]oleic acid, butyrate led to a significant reduction of secreted, labeled triglycerides (27%; P < 0.01) and phospholipids (25%; P < 0.05). Similarly, butyrate significantly decreased the incorporation of [14C]acetate into exported cholesteryl ester (49%; P < 0.005). As expected from these results, with [14C]oleic acid as a precursor, butyrate significantly (P < 0.05) diminished the delivery of radiolabeled chylomicrons and very low-density lipoproteins. In parallel, [35S]methionine pulse labeling of Caco-2 cells revealed the concomitant inhibitory effect of butyrate on the synthesis of apolipoproteins B-48 (28%; P < 0.05) and A-I (32%; P < 0.01). Collectively, our data indicate that butyrate may influence lipid metabolism in Caco-2 cells, thus suggesting a potential regulation of intestinal fat absorption and circulating lipoprotein concentrations.

Objective: It remains uncertain whether leptin and adiponectin levels are correlated in maternal vs. fetal circulations. Little is known about whether leptin and adiponectin affect insulin sensitivity during fetal life. Design and Methods: In a prospective singleton pregnancy cohort (n ¼ 248), we investigated leptin and adiponectin concentrations in maternal (at 24-28 and 32-35 weeks of gestation) and fetal circulations, and their associations with fetal insulin sensitivity (glucose/insulin ratio, proinsulin level). Results: Comparing concentrations in cord vs. maternal blood, leptin levels were 50% lower, but adiponectin levels more than doubled. Adjusting for gestational age at blood sampling, consistent and similar positive correlations (correlation coefficients: 0.31-0.34, all P < 0.0001) were observed in leptin or adiponectin levels in maternal (at 24-28 or 32-25 weeks of gestation) vs. fetal circulations. For each SD increase in maternal plasma concentration at 24-28 weeks, cord plasma concentration increased by 12.7 (95% confidence interval 6.8-18.5) ng/ml for leptin, and 2.9 (1.8-4.0) mg/ml for adiponectin, respectively (adjusted P < 0.0001). Fetal insulin sensitivity was negatively associated with cord blood leptin (each SD increase was associated with a 5.4 (2.1-8.7) mg/dl/mU/ml reduction in cord plasma glucose/insulin ratio, and a 5.6 (3.9, 7.4) pmol/l increase in proinsulin level, all adjusted P < 0.01) but not adiponectin (P > 0.4) levels). Similar associations were observed in nondiabetic full-term pregnancies (n ¼ 211). Conclusions:The results consistently suggest a maternal impact on fetal leptin and adiponectin levels, which may be an early life pathway in maternal-fetal transmission of the propensity to obesity and insulin resistance.

Although a critical role of microsomal transfer protein (MTP) has been recognized in the assembly of nascent apolipoprotein B (apoB)-containing lipoproteins, it remains unclear where and how MTP transfers lipids in the secretory pathway during the maturational process of apoB lipidation. The aims of this study were to determine whether MTP functions in the secretory pathway as well as in the endoplasmic reticulum and whether its large 97-kDa subunit interacts with the small 58-kDa protein disulfide isomerase (PDI) subunit and apoB, particularly in the Golgi apparatus. Using a high resolution immunogold approach combined with specific polyclonal antibodies, the large and small subunits of MTP were observed over the rough endoplasmic reticulum and the Golgi. Double immunocytochemical detection unraveled the colocalization of MTP and PDI as well as MTP and apoB in these same subcellular compartments. To confirm the spatial contact of these proteins, Golgi fractions were isolated, homogenized, and incubated with an anti-MTP large subunit antibody. Immunoprecipitates were applied on SDS-PAGE and then transferred on to nitrocellulose. Immunoblotting the membrane with PDI and apoB antibodies confirmed the colocalization of these proteins with MTP. Furthermore, MTP activity assay disclosed a substantial triglyceride transfer in the Golgi fractions. The occurrence of membrane-associated apoB in the Golgi, coupled with its interaction with active MTP, suggests an important role for the Golgi in the biogenesis of apoB-containing lipoproteins.Lipids constitute the most calorically dense dietary nutrients. They must undergo emulsification within the intestinal lumen, cell membrane permeation, intracellular esterification, and incorporation into chylomicrons before reaching the circulatory system (for reviews, see Refs. 1-4). Despite significant progress, our understanding of the complex biosynthetic process involved in the formation and secretion of triglyceride-rich lipoprotein particles remains rather fragmentary. In particular, we know little about the sequential multistep assembly of apolipoproteins and lipids or the topology of the proteins in intracellular organelles implicated in lipoprotein production.The study of naturally occurring mutations and genetic variations in humans has greatly contributed to the identification of the proteins essential to the synthetic pathway and to the delineation of key metabolic mechanisms (5-11). Inherited disorders of apolipoprotein B (apoB) 1 and microsomal transfer protein (MTP) deficiency have provided a unique source for delineating, at least partially, the role of these specific proteins as well as elucidating the intracellular mechanisms that result in lipid absorption and transport (5-11). The addition of core lipid to the nascent lipoprotein particle is thought to occur in conjunction with the translation and translocation of apoB in the ER (12)(13)(14)(15). During this process, apoB remains tightly bound to the ER membrane, where it is folded. The initial complement of lipid...

Recently, the idea was advanced that short-chain fatty acids (SCFA) may potentially regulate intestinal fat absorption. The aim of this investigation was to examine the effects of butyrate on the intracellular events governing the assembly of triglyceride-lipoproteins in enterocytes. To this end, differentiated human Caco-2 cells were exposed to 10 or 20 mmol/L butyrate for 20 h. The incubation of Caco-2 cells with butyrate decreased cholesteryl ester (P < 0.005) export in the basolateral medium, probably due to reduced activity of DL-3-hydroxy-3-methyl-glutaryl-CoA reductase (P < 0.02), the rate-limiting enzyme in cholesterol synthesis. Furthermore, a drop was noted in the protein expression of microsomal triglyceride transfer protein (P < 0.03), concomitant with the inhibition of de novo apolipoprotein B-48 synthesis (P < 0.02) and triglyceride-rich lipoprotein output (P < 0.03). Our results support the hypothesis that SCFA can influence lipoprotein concentrations by limiting lipid release from the small intestine into the circulation.