APOE4 encoding apolipoprotein (Apo)E4 is the strongest genetic risk factor for Alzheimer\'s disease (AD). ApoE is key in intercellular lipid trafficking. Fatty acids are essential for brain integrity and cognitive performance and are implicated in neurodegeneration. We determined the sex- and age-dependent effect of AD and APOE4 on brain free fatty acid (FFA) profiles. FFA profiles were determined by LC-MS/MS in hippocampus, cortex, and cerebellum of female and male, young (≤3 months) and older (>5 months), transgenic APOE3 and APOE4 mice with and without five familial AD (FAD) mutations (16 groups; n = 7-10 each). In the different brain regions, females had higher levels than males of either saturated or polyunsaturated FFAs or both. In the hippocampus of young males, but not of older males, APOE4 and FAD each induced 1.3-fold higher levels of almost all FFAs. In young and older females, FAD and to a less extent APOE4-induced shifts among saturated, monounsaturated, and polyunsaturated FFAs without affecting total FFA levels. In cortex and cerebellum, APOE4 and FAD had only minor effects on individual FFAs. The effects of APOE4 and FAD on FFA levels and FFA profiles in the three brain regions were strongly dependent of sex and age, particularly in the hippocampus. Here, most FFAs that are affected by FAD are similarly affected by APOE4. Since APOE4 and FAD affected hippocampal FFA profiles already at young age, these APOE4-induced alterations may modulate the pathogenesis of AD.

This work examines the insecticidal activity of octanoic acid (C8:0), a short-chain fatty acid detected in entomopathogenic fungus - Conidiobolus coronatus medium, against Lucilia sericata larvae and adults. The LD50 value was calculated as 3.04±0.26 µg/mg (3040 mg/kg) of insect body mass, which places the compound in category 5 of acute toxicity (slightly hazardous). The presented research also describes its probable mechanism, with a particular focus on changes in two main insect defense mechanisms: (1) the composition of the cuticle (GC-MS analysis) and (2) immunocompetent cells (microscopic analysis of cultured hemocytes). More precisely, octanoic acid application resulted in changes in cuticular free fatty acid (FFA) profiles in both adults and larvae; generally, treatment increased short-chain FFAs, and a decrease of middle- and long-chain FFAs. Both in vivo and in vitro applications of octanoic acid resulted in vacuolisation, disintegration, and destruction of nets formed by plasmatocytes. As the compound has also previously been found to be toxic against Galleria mellonella, it appears to have lethal potential against insects in both the Orders Diptera and Lepidoptera, indicating it may have strong entomopathogenic potential. It is worth noting that octanoic acid is approved as a food additive with well-documented insecticidal activity, and hence may be a valuable component in the design of new insecticides that are safe for both humans and the environment.

The pituitary is the central endocrine gland with effects on metabolic dysfunction-associated steatotic liver disease (MASLD). However, it is not clear whether the pituitary responds to free fatty acid (FFA) toxicity, thus dysregulating hepatic lipid metabolism. Here, we demonstrate that decreased prolactin (PRL) levels are involved in the association between FFA and MASLD based on a liver biospecimen-based cohort. Moreover, overloaded FFAs decrease serum PRL levels, thus promoting liver steatosis in mice with both dynamic diet intervention and stereotactic pituitary FFA injection. Mechanistic studies show that excessive FFA sensing in pituitary lactotrophs inhibits the synthesis and secretion of PRL in a cell-autonomous manner. Notably, inhibiting excessive lipid uptake using pituitary stereotaxic virus injection or a specific drug delivery system effectively ameliorates hepatic lipid accumulation by improving PRL levels. Targeted inhibition of pituitary FFA sensing may be a potential therapeutic target for liver steatosis.

Lipotoxicity has been considered the main cause of pancreatic beta-cell failure during type 2 diabetes development. Lipid droplets (LD) are believed to regulate the beta-cell sensitivity to free fatty acids (FFA), but the underlying molecular mechanisms are largely unclear. Accumulating evidence points, however, to an important role of intracellular sphingosine-1-phosphate (S1P) metabolism in lipotoxicity-mediated disturbances of beta-cell function. In the present study, we compared the effects of an increased irreversible S1P degradation (S1P-lyase, SPL overexpression) with those associated with an enhanced S1P recycling (overexpression of S1P phosphatase 1, SGPP1) on LD formation and lipotoxicity in rat INS1E beta-cells. Interestingly, although both approaches led to a reduced S1P concentration, they had opposite effects on the susceptibility to FFA. Overexpression of SGPP1 prevented FFA-mediated caspase-3 activation by a mechanism involving an enhanced lipid storage capacity and prevention of oxidative stress. In contrast, SPL overexpression limited lipid droplet biogenesis, content and size, while accelerating lipophagy. This was associated with FFA-induced hydrogen peroxide formation, mitochondrial fragmentation and dysfunction, as well as ER stress. These changes coincided with upregulation of proapoptotic ceramides, but were independent of lipid peroxidation rate. Also in human EndoC-βH1 beta-cells suppression of SPL with simultaneous overexpression of SGPP1 led to a similar and even more pronounced LD phenotype as that in INS1E-SGPP1 cells. Thus, intracellular S1P turnover significantly regulates LD content and size, and influences beta-cell sensitivity to FFA.

The present work evaluated how a native pea protein isolate (PPI) affects the key roles carried out by bile salts (BS) in lipid digestion by means of the in vitro static INFOGEST protocol. Two gastric residence times were evaluated (10 and 60 min), and then the peptides obtained (GPPP) were mixed with BS at physiological concentration in simulated intestinal fluid to understand how they interact with BS both at the bulk and at the interface. Both GPPP give rise to a film with a predominant viscous character that does not constitute a barrier to the penetration of BS, but interact with BS in the bulk duodenal fluid. When the peptides flushing from the stomach after the different gastric residence times undergo duodenal digestion, it was found that for the longer gastric residence time the percentage of soluble fraction in the duodenal phase, that perform synergistically with BS micelles, was twice that of the lower residence time, leading to an increase in the solubilization of oleic acid. These results finally lead to a greater extent of lipolysis of olive oil emulsions. This work demonstrates the usefulness of in vitro models as a starting point to study the influence of gastric residence time of pea protein on its interaction with BS, affecting lipolysis. Pea proteins were shown to be effective emulsifiers that synergistically perform with BS improving the release and bioaccessibility of bioactive lipids as olive oil.

The growing demand for phycobiliproteins from microalgae generates a significant volume of by-products, such as extraction cakes. These cakes are enriched with products of interest for the cosmetics market, namely free fatty acids, particularly polyunsaturated (PUFA). In this work, two cakes, one of spirulina and one of Porphyridium cruentum, were valorized using innovative natural hydrophobic deep eutectic solvents (NaDES) based on alkanediols. The most promising NaDES, as determined by physicochemical properties and screening, are mixtures of alkanediols and fatty acids. These include the mixtures of 1,3-propanediol and octanoic acid (1:5, mol/mol) and 1,3-propanediol and octanoic and decanoic acid (1:3:1, mol/mol). Two extractive processes were implemented: ultrasound-assisted extraction and an innovative mechanical process involving dual asymmetric centrifugation. The second process resulted in the production of extracts significantly enriched in PUFA, ranging from 65 to 220 mg/g dry matter with the two cakes. The extracts and NaDES demonstrated good safety with respect to epidermal keratinocyte viability (>80% at 200 µg/mL). The study of their impact on commensal and pathogenic cutaneous bacteria demonstrated significant effects on the viability of Staphylococcus aureus and Staphylococcus epidermidis (>50% decrease at 200 µg/mL) while preserving Corynebacterium xerosis and Cutibacterium acnes. These results highlight the potential of valorizing these co-products using alkanediol-based NaDES, in a strategy combining an active vector (NaDES) and a growth regulator extract, for the management of cutaneous dysbiosis involving staphylococci.

This study aimed to determine whether obese men with nonalcoholic fatty liver disease (NAFLD) display differences between those with simple steatosis versus steatohepatitis (NASH) in splanchnic and hepatic FFA and VLDL-triglycerides (VLDL-TG) balances. The study involved 17 obese men with biopsy-proven NAFLD (9 with NASH and 8 with simple steatosis). We used hepatic vein catheterization in combination with [3H]palmitate and [14C]VLDL-TG tracers to measure splanchnic palmitate and VLDL-TG uptake and release rates during basal and hyperinsulinemic conditions. Indocyanine green was used to measure splanchnic plasma flow. Splanchnic palmitate uptake was similar in the two groups and significantly reduced during hyperinsulinemia (NASH: 62 (48-77) versus 38 (18-58) μmol/min; simple steatosis: 62 (46-78) versus 45 (25-65) μmol/min, mean (95% CI), basal versus clamp periods, respectively, P = 0.02 time-effect). Splanchnic palmitate release was also comparable between groups and nonsignificantly diminished during hyperinsulinemia. The percent palmitate delivered to the liver originating from visceral adipose tissue lipolysis was similar and unchanged by hyperinsulinemia. Splanchnic uptake and release of VLDL-TG were similar between groups. Hyperinsulinemia suppressed VLDL-TG release (P <0.05 time-effect) in both groups. Insulin-mediated glucose disposal was similar in the two groups (P = 0.54). Obese men with NASH and simple steatosis have similar splanchnic uptake and release of FFA and VLDL-TG and a similar proportion of FFA from visceral adipose tissue lipolysis delivered to the liver. These results demonstrate that the splanchnic balances of FFA and VLDL-TG do not differ between obese men with NASH and those with simple steatosis.

In our previous study, a chemical derivatization reagent named 5-(dimethylamino) naphthalene-1-sulfonyl piperazine (Dns-PP) was developed to enhance the chromatographic retention and the mass spectrometric response of free fatty acids (FFAs) in reversed-phase liquid chromatography coupled with electrospray ionization-mass spectrometry (RPLC-ESI-MS). However, Dns-PP exhibited strong preferences for long-chain FFAs, with limited improvement for short- or medium-chain FFAs. In this study, a new series of labeling reagents targeting FFAs were designed, synthesized, and evaluated. Among these reagents, Tmt-PP (N2, N2, N4, N4-tetramethyl-6-(4-(piperazin-1-ylsulfonyl) phenyl)-1,3,5-triazine-2,4-diamine) exhibited the best MS response and was selected for further evaluations. We compared Tmt-PP with Dns-PP and four commonly used carboxyl labeling reagents from existing studies, demonstrating the advantages of Tmt-PP. Further comparisons between Tmt-PP and Dns-PP in measuring FFAs from biological samples revealed that Tmt-PP labeling enhanced the MS response for about 80 % (30/38) of the measured FFAs, particularly for short- and medium-chain FFAs. Moreover, Tmt-PP labeling significantly improved the chromatographic retention of short-chain FFAs. To ensure accurate quantification, we developed a stable isotope-labeled Tmt-PP (i.e., d12-Tmt-PP) to react with chemical standards and serve as one-to-one internal standards (IS). The method was validated for accuracy, precision, sensitivity, linearity, stability, extraction efficiency, as well as matrix effect. Overall, this study introduced a new chemical derivatization reagent Tmt-PP (d12-Tmt-PP), providing a sensitive and accurate option for quantifying FFAs in biological samples.

There is a growing interest in developing highly viscous lipid foods using plant protein and polysaccharide gum-based emulsion technology. However, gaps remain in understanding the rheological, microstructural, and digestive properties of plant proteins like soybean protein isolate (SPI) in combination with various gums. This study investigates how combining SPI and peach gum (PG) affects rheology and lipolysis of oil-in-water (O/W) emulsions containing 20 wt% soybean oil. Emulsions with varying SPI and PG compositions including SPI-PG single and SPI/PG mixed droplet systems were prepared. Heating induced alterations in viscosity (e.g., SPI-PG from 14.88 to 90.27 Pa·s and SPI/PG from 9.66 to 85.32 Pa·s) and microstructure revealing aggregate formation at oil-water interface. The viscosity decreased significantly from the oral to intestinal phase (SPI-PG: 28.10 to 0.19 Pa·s, SPI/PG: 21.27 to 0.10 Pa·s). These changes affected lipid digestion, notably in SPI-PG and SPI/PG emulsions where a compact interface hindered lipolysis during digestion. Interestingly, free fatty acid (FFA) release during small intestinal phase followed a different order: SPI (82.51 %) > SPI-PG (70.77 %) > SPI/PG (63.60 %) > PG (56.09 %). This study provides insights into creating highly viscous O/W spreads with improved rheology, stability, and delayed lipid digestion, offering potential benefits in food product formulation.

Intestinal dysfunction plays a pivotal role in the development of acute pancreatitis (AP), however, the underlying mechanisms of intestinal dysfunction on severity of hyperlipidemic acute pancreatitis (HLAP) are still unclear. Herein, we explored the role of intestinal function on the severity of HLAP. We found that HLAP patients exhibit higher lipid and inflammatory response than AP patients. Hyperlipidemia significantly elevates serum lipids and worsen pancreatic damage in AP mice. In addition, significant exacerbated intestinal barrier damage and inflammation were observed in experimental HLAP mice, as evidenced by increased serum amylase and lipase levels, and pancreatic edema. Further, RNA-Seq showed that a markedly decrease of glutathione S-transferase pi (GSTpi) in colonic tissue of HLAP mice compared with AP mice, accompanied with increased serum lipopolysaccharides level. However, colonic GSTpi overexpression by adeno-associated virus significantly attenuated intestinal damage and subsequent pancreatic inflammation in HLAP mice. Mechanistically, GSTpi mitigated HLAP-mediated colonic NLRP3 inflammasome activation and barrier dysfunction. These results suggest that intestinal GSTpi deficiency exacerbates the severity of experimental HLAP, providing new insights for the clinical treatment of HLAP.