Isomer-specific effects of conjugated linoleic acid on HDL functionality associated with reverse cholesterol transport

Engineering Yarrowia lipolytica for Sustainable Production of the Pomegranate Seed Oil-Derived Punicic Acid

Punicic acid is a conjugated linolenic acid with various biological activities including antiobesity, antioxidant, anticancer, and anti-inflammatory effects. It is often used as a nutraceutical, dietary additive, and animal feed. Currently, punicic acid is primarily extracted from pomegranate seed oil, but it is restricted due to the extended growth cycle, climatic limitations, and low recovery level. There have also been reports on the chemical synthesis of punicic acid, but it resulted in a mixture of structurally similar isomers, requiring additional purification/separation steps. In this study, a comprehensive strategy for the production of punicic acid in Yarrowia lipolytica was implemented by pushing the supply of linoleic acid precursors in a high-oleic oil strain, expressing multiple copies of the fatty acid conjugase gene from Punica granatum, engineering the acyl-editing pathway to improve the phosphatidylcholine pool, and promoting the assembly of punicic acid in the form of triglycerides. The optimal strain with high oil production capacity and a significantly increased punicic acid ratio accumulated 3072.72 mg/L punicic acid, accounting for 6.19% of total fatty acids in fed-batch fermentation, providing a viable, sustainable, and green approach for punicic acid production to substitute plant extraction and chemical synthesis production.

Advances in research on microbial conjugated linoleic acid bioconversion

Conjugated linoleic acid (CLA) is a functional food ingredient with prebiotic properties that provides health benefits for various human pathologies and disorders. However, limited natural CLA sources in animals and plants have led microorganisms like Lactobacillus and Bifidobacterium to emerge as new CLA sources. Microbial conversion of linoleic acid to CLA is mediated by linoleic acid isomerase and multicomponent enzymatic systems, with CLA production efficiency dependent on microbial species and strains. Additionally, complex factors like LA concentration, growth status, culture substrates, precursor type, prebiotic additives, and co-cultured microbe identity strongly influence CLA production and isomer composition. This review summarizes advances in the past decade regarding microbial CLA production, including bacteria and fungi. We highlight CLA production and potential regulatory mechanisms and discuss using microorganisms to enhance CLA content and nutritional value of fermented products. We also identify primary microbial CLA production bottlenecks and provide strategies to address these challenges and enhance production through functional gene and enzyme mining and downstream processing. This review aims to provide a reference for microbial CLA production and broaden the understanding of the potential probiotic role of microbial CLA producers.

Maternal consumption of conjugated linoleic acid improves tolerance to glucose and hdl-cholesterol in the rat progeny

Our study evaluates the impacts of maternal consumption of different levels of CLA during pregnancy and lactation on physical and metabolic changes in the rat progeny. Three groups were formed: control (CG) - diet without CLA; CLA1 - diet containing 1% CLA; and CLA3 - diet containing 3% CLA. Murinometry, body fat collection, biochemical analysis, glycemic curves, liver fat amount, and fatty acid profiles of the liver were studied. The data were analyzed by ANOVA, followed by the Tukey test (p < 0.05). The CLA3 group presented highest body weight, feed intake and BMI (p < 0.05). The retroperitoneal fat, epididymal fat, and body fat index were higher in the CLA1 and CLA3 groups (p < 0.05) but no difference was observed for mesenteric fat. Yet in contrast, the experimental groups presented lower abdominal circumference and glycemic curves when compared to the CG (p < 0.05). CLA1 and CLA3 groups presented higher values of total cholesterol and HDL-cholesterol (p < 0.05), yet no difference was found in serum triglycerides or LDL. The CLA3 group presented less n-3, n-6, total PUFA, and arachidonic acid in liver fat (p < 0.05). The CLA1 and CLA3 groups were higher in total MUFA in the liver fat. In conclusion, CLA when consumed during gestation and lactation increased: tolerance to glucose, HDL, and the body fat index in the offspring. Only the CLA3 group presented reduced total PUFA, n-3, n-6 and arachidonic acid in the offspring's liver.

Isomer-Specific Effects of cis-9,trans-11- and trans-10,cis-12-CLA on Immune Regulation in Ruminal Epithelial Cells

Simple Summary

The significant contribution of rumen microbiota to the balance of the innate immunity of rumen epithelium has been extensively verified. As the natural rumen microbial metabolites, information regarding the immunoprotective effects of different conjugated linoleic acid (CLA) isomers on ruminal epithelial cells (RECs) is limited. In this study, the 100 μM trans-10,cis-12-CLA exerted better anti-inflammatory effects than the cis-9,trans-11-CLA by significantly downregulating the expression of genes related to inflammation, cell proliferation and migration in RECs upon lipopolysaccharide (LPS) stimulation. The trans-10,cis-12-CLA, but not cis-9,trans-11-CLA, significantly suppressed the biological signals of gene ontology (GO) terms’ response to lipopolysaccharide, the regulation of signal transduction and cytokine production and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways NF-κB, chemokine, NOD-like receptor, Hippo, PI3K-Akt, TGF-β and Rap1 signaling in RECs upon LPS stimulation. Furthermore, pretreatment with trans-10,cis-12-CLA significantly reduced the expression of lipogenic genes and the biosynthesis of the unsaturated fatty acid pathway in RECs compared with the LPS group, however, cis-9,trans-11-CLA exhibited the opposite results. These results suggest the distinct isomer differences of CLA in the regulation of inflammatory responses and adipocytokine signaling in RECs and will provide important references for determining their target use in the future.

Abstract

In this study, we used transcriptomics and qPCR to investigate the potential immunoprotective effects of different conjugated linoleic acid (CLA) isomers, the natural rumen microbial metabolites, on lipopolysaccharide (LPS)-induced inflammation of ruminal epithelial cells (RECs) in vitro. The results showed that 100 μM trans-10,cis-12-CLA exerted higher anti-inflammatory effects than cis-9,trans-11-CLA by significantly downregulating the expression of genes related to inflammation, cell proliferation and migration in RECs upon LPS stimulation. Transcriptomic analyses further indicated that pretreatment with trans-10,cis-12-CLA, but not cis-9,trans-11-CLA, significantly suppressed the biological signals of GO terms’ response to LPS, the regulation of signal transduction and cytokine production and KEGG pathways NF-κB, chemokine, NOD-like receptor, Hippo, PI3K-Akt, TGF-β and Rap1 signaling in RECs upon LPS stimulation. Furthermore, pretreatment with trans-10,cis-12-CLA significantly reduced the expression of lipogenic genes and the biosynthesis of the unsaturated fatty acid pathway in RECs compared with the LPS group, however, cis-9,trans-11-CLA exhibited the opposite results. These results suggest the distinct isomer differences of CLA in the regulation of inflammatory responses and adipocytokine signaling in RECs and will provide important references for determining their target use in the future.

cis 9, trans 11, but not trans 10, cis 12 CLA isomer, impairs intestinal epithelial barrier function in IPEC-J2 cells and mice through activation of GPR120-[Ca2+]i and the MLCK signaling pathway

This study aimed to investigate the effects of conjugated linoleic acid (CLA) on intestinal epithelial barrier function and explore the underlying mechanisms. IPEC-J2 cells and mice were treated with different CLA isomers. The intestinal epithelial barrier function determined by transepithelial electrical resistance (TEER), the expression of tight junction proteins, and the involvement of G-protein coupled receptor 120 (GPR120), intracellular calcium ([Ca2+]i) and myosin light chain kinase (MLCK) were assessed. In vitro, c9, t11-CLA, but not t10, c12-CLA isomer, impaired epithelial barrier function in IPEC-J2 by downregulating the expression of tight junction proteins. Meanwhile, c9, t11-CLA isomer enhanced GPR120 expression, while knockdown of GPR120 eliminated the impaired epithelial barrier function induced by c9, t11-CLA isomer. In addition, c9, t11-CLA isomer increased [Ca2+]i and activated the MLCK signaling pathway in a GPR120-dependent manner. However, chelation of [Ca2+]i reversed c9, t11-CLA isomer-induced MLCK activation and the epithelial barrier function impairment of IPEC-J2. Furthermore, inhibition of MLCK totally abolished the impairment of epithelial barrier function induced by c9, t11-CLA. In vivo, dietary supplementation of c9, t11-CLA rather than t10, c12-CLA isomer decreased the expression of intestinal tight junction proteins and GPR120, increased intestinal permeability, and activated the MLCK signaling pathway in mice. Taken together, our findings showed that c9, t11-CLA, but not t10, c12-CLA isomer, impaired intestinal epithelial barrier function in IPEC-J2 cells and mice through activation of GPR120-[Ca2+]i and the MLCK signaling pathway. These data provided new insight into the regulation of the intestinal epithelial barrier by different CLA isomers and more references for CLA application in humans and animals.

Diosgenin alleviates hypercholesterolemia via SRB1/CES-1/CYP7A1/FXR pathway in high-fat diet-fed rats

Phytosterol diosgenin (DG) exhibits cholesterol-lowering properties. Few studies focused on the underlying mechanism of DG attenuation of hypercholesterolemia by promoting cholesterol metabolism. To investigate the roles of SRB1/CES-1/CYP7A1/FXR pathways in accelerating cholesterol elimination and alleviating hypercholesterolemia, a rat model of hypercholesterolemia was induced by providing a high-fat diet (HFD). Experimental rat models were randomly divided into a normal control (Con) group, HFD group, low-dose DG (LDG) group (150 mg/kg/d), high-dose DG (HDG) group (300 mg/kg) and Simvastatin (Sim) group (4 mg/kg/d). Body weights, serum and hepatic lipid parameters of rats were tested. The expression levels of scavenger receptor class B type I (SRB1), carboxylesterase-1 (CES-1), cholesterol7α- hydroxylase (CYP7A1), and farnesoid X receptor (FXR) were determined. The results showed that DG reduced weight and lowered lipid levels in HFD-fed rats. Pathological morphology analyses revealed that DG notably improved hepatic steatosis and intestinal structure. Further studies showed the increased hepatic SRB1, CES-1, CYP7A1 and inhibited FXR-mediated signaling in DG-fed rats, which contributing to the decrease of hepatic cholesterol. DG also increased intestinal SRB1 and CES-1, inhibiting cholesterol absorption and promoting RCT. The expression levels of these receptors in the HDG group were higher than LDG and Sim groups. These data suggested that DG accelerated reverse cholesterol transport (RCT) and enhanced cholesterol elimination via SRB1/CES-1/CYP7A1/FXR pathway, and DG might be a new candidate for the alleviation of hypercholesterolemia.

Depression in middle and older adulthood: the role of immigration, nutrition, and other determinants of health in the Canadian longitudinal study on aging

BACKGROUND

Little is known about depression in middle-aged and older Canadians and how it is affected by health determinants, particularly immigrant status. This study examined depression and socio-economic, health, immigration and nutrition-related factors in older adults.

METHODS

Using weighted comprehensive cohort data from the baseline Canadian Longitudinal Study on Aging (n = 27,162) of adults aged 45-85, gender-specific binary logistic regression was conducted with the cross-sectional data using the following variables: 1) Depression (outcome) measured using the Center for Epidemiologic Studies Short Depression (CESD-10) rating scale; 2) Immigration status: native-born, recent and mid-term (< 20 years), and long-term immigrants (≥20 years); and 3) covariates: socioeconomic status, physical health (e.g., multi-morbidity), health behavior (e.g., substance use), over-nutrition (e.g., anthropometrics), under-nutrition (e.g., nutrition risk), and dietary intake.

RESULTS

The sample respondents were mainly Canadian-born (82.6%), women (50.6%), 56-65 years (58.9%), earning between C$50,000-99,999 (33.2%), and in a relationship (69.4%). When compared to Canadian-born residents, recent, mid-term (< 20 years), and longer-term (≥ 20 years) immigrant women were more likely to report depression and this relationship was robust to adjustments for 32 covariates (adjusted ORs = 1.19, 2.54, respectively, p < 0.001). For women, not completing secondary school (OR = 1.23, p < 0.05), stage 1 hypertension (OR = 1.31, p < 0.001), chronic pain (OR = 1.79, p < 0.001), low fruit/vegetable intakes (OR = 1.33, p < 0.05), and fruit juice (OR = 1.80, p < 0.001), chocolate (ORs = 1.15-1.66, p's < 0.05), or salty snack (OR = 1.19, p < 0.05) consumption were associated with depression. For all participants, lower grip strength (OR = 1.25, p < 0.001) and high nutritional risk (OR = 2.24, p < 0.001) were associated with depression. For men, being in a relationship (OR = 0.62, p < 0.001), completing post-secondary education (OR = 0.82, p < 0.05), higher fat (ORs = 0.67-83, p's < 0.05) and omega-3 egg intake (OR = 0.86, p < 0.05) as well as moderate intakes of fruits/vegetables and calcium/high vitamin D sources (ORs = 0.71-0.743, p's < 0.05) predicted a lower likelihood of depression. For men, chronic conditions (ORs = 1.36-3.65, p's < 0.001), chronic pain (OR = 1.86, p < 0.001), smoking (OR = 1.17, p < 0.001), or chocolate consumption (ORs = 1.14-1.72, p's < 0.05) predicted a higher likelihood of depression.

CONCLUSIONS

The odds of developing depression were highest among immigrant women. Depression in middle-aged and older adults is also associated with socioeconomic, physical, and nutritional factors and the relationships differ by sex. These results provide insights for mental health interventions specific to adults aged 45-85.

Production of conjugated fatty acids: A review of recent advances

Conjugated fatty acids (CFAs) have received a deal of attention due to the increasing understanding of their beneficial physiological effects, especially the anti-cancer effects and metabolism-regulation activities. However, the production of CFAs is generally difficult. Several challenges are the low CFAs content in natural sources, the difficulty to chemically synthesize target CFA isomers in high purity, and the sensitive characteristics of CFAs. In this article, the current technologies to produce CFAs, including physical, chemical, and biotechnical approaches were summarized, with a focus on the conjugated linoleic acids (CLAs) and conjugated linolenic acids (CLNAs) which are the most common investigated CFAs. CFAs usually demonstrate stronger physiological effects than other non-conjugated fatty acids; however, they are more sensitive to heat and oxidation. Consequently, the quality control throughout the entire production process of CFAs is significant. Special attention was given to the micro- or nano-encapsulation which presented as an emerging technique to improve the bioavailability and storage stability of CFAs. The current applications of CFAs and the potential research directions were also discussed.