Omega-3 Fatty Acids and FFAR4

Integration of selective sweeps across the sheep genome: understanding the relationship between production and adaptation traits

BACKGROUND

Livestock populations are under constant selective pressure for higher productivity levels for different selective purposes. This pressure results in the selection of animals with unique adaptive and production traits. The study of genomic regions associated with these unique characteristics has the potential to improve biological knowledge regarding the adaptive process and how it is connected to production levels and resilience, which is the ability of an animal to adapt to stress or an imbalance in homeostasis. Sheep is a species that has been subjected to several natural and artificial selective pressures during its history, resulting in a highly specialized species for production and adaptation to challenging environments. Here, the data from multiple studies that aim at mapping selective sweeps across the sheep genome associated with production and adaptation traits were integrated to identify confirmed selective sweeps (CSS).

RESULTS

In total, 37 studies were used to identify 518 CSS across the sheep genome, which were classified as production (147 prodCSS) and adaptation (219 adapCSS) CSS based on the frequency of each type of associated study. The genes within the CSS were associated with relevant biological processes for adaptation and production. For example, for adapCSS, the associated genes were related to the control of seasonality, circadian rhythm, and thermoregulation. On the other hand, genes associated with prodCSS were related to the control of feeding behaviour, reproduction, and cellular differentiation. In addition, genes harbouring both prodCSS and adapCSS showed an interesting association with lipid metabolism, suggesting a potential role of this process in the regulation of pleiotropic effects between these classes of traits.

CONCLUSIONS

The findings of this study contribute to a deeper understanding of the genetic link between productivity and adaptability in sheep breeds. This information may provide insights into the genetic mechanisms that underlie undesirable genetic correlations between these two groups of traits and pave the way for a better understanding of resilience as a positive ability to respond to environmental stressors, where the negative effects on production level are minimized.

Predicting FFAR4 agonists using structure-based machine learning approach based on molecular fingerprints

Free Fatty Acid Receptor 4 (FFAR4), a G-protein-coupled receptor, is responsible for triggering intracellular signaling pathways that regulate various physiological processes. FFAR4 agonists are associated with enhancing insulin release and mitigating the atherogenic, obesogenic, pro-carcinogenic, and pro-diabetogenic effects, normally associated with the free fatty acids bound to FFAR4. In this research, molecular structure-based machine-learning techniques were employed to evaluate compounds as potential agonists for FFAR4. Molecular structures were encoded into bit arrays, serving as molecular fingerprints, which were subsequently analyzed using the Bayesian network algorithm to identify patterns for screening the data. The shortlisted hits obtained via machine learning protocols were further validated by Molecular Docking and via ADME and Toxicity predictions. The shortlisted compounds were then subjected to MD Simulations of the membrane-bound FFAR4-ligand complexes for 100 ns each. Molecular analyses, encompassing binding interactions, RMSD, RMSF, RoG, PCA, and FEL, were conducted to scrutinize the protein-ligand complexes at the inter-atomic level. The analyses revealed significant interactions of the shortlisted compounds with the crucial residues of FFAR4 previously documented. FFAR4 as part of the complexes demonstrated consistent RMSDs, ranging from 3.57 to 3.64, with minimal residue fluctuations 5.27 to 6.03 nm, suggesting stable complexes. The gyration values fluctuated between 22.8 to 23.5 nm, indicating structural compactness and orderliness across the studied systems. Additionally, distinct conformational motions were observed in each complex, with energy contours shifting to broader energy basins throughout the simulation, suggesting thermodynamically stable protein-ligand complexes. The two compounds CHEMBL2012662 and CHEMBL64616 are presented as potential FFAR4 agonists, based on these insights and in-depth analyses. Collectively, these findings advance our comprehension of FFAR4's functions and mechanisms, highlighting these compounds as potential FFAR4 agonists worthy of further exploration as innovative treatments for metabolic and immune-related conditions.

Double knockout of FFAR4 and FGF21 aggravates metabolic disorders in mice

Several investigations have examined the involvement of free fatty acid receptor 4 (FFAR4) in metabolic disorders, but its action remains controversial. To investigate whether endogenous fibroblast growth factor 21 (FGF21)-mediated signaling controls the metabolic status in FFAR4-deficient mice, we generated FFAR4/FGF21 double knockout (DKO) mice. We also evaluated the role of FGF21 on glucose and lipid metabolism in FFAR4 KO mice fed a high-fat diet. Levels of FGF21 were significantly increased in FFAR4-deficient mice and double deletion of FGF21 and FFAR4 led to severe metabolic disorders. Additionally, FFAR4/FGF21 DKO mice displayed metabolic abnormalities that may be caused by decreased energy expenditure. Collectively, this study characterized the effects of endogenous FGF21, which acts as a master feedback regulator in the absence of FFAR4.

Full-Length Transcriptome and Gene Expression Analysis of Different Ovis aries Adipose Tissues Reveals Transcript Variants Involved in Lipid Biosynthesis

Sheep have historically been bred globally as a vital food source. To explore the transcriptome of adipose tissue and investigate key genes regulating adipose metabolism in sheep, adipose tissue samples were obtained from F1 Dorper × Hu sheep. High-throughput sequencing libraries for second- and third-generation sequencing were constructed using extracted total RNA. Functional annotation of differentially expressed genes and isoforms facilitated the identification of key regulatory genes and isoforms associated with sheep fat metabolism. SMRT-seq generated 919,259 high-accuracy cDNA sequences after filtering. Full-length sequences were corrected using RNA-seq sequences, and 699,680 high-quality full-length non-chimeric (FLNC) reads were obtained. Upon evaluating the ratio of total lengths based on FLNC sequencing, it was determined that 36,909 out of 56,316 multiple-exon isoforms met the criteria for full-length status. This indicates the identification of 330,375 full-length FLNC transcripts among the 370,114 multiple-exon FLNC transcripts. By comparing the reference genomes, 60,276 loci and 111,302 isoforms were identified. In addition, 43,423 new genes and 44,563 new isoforms were identified. The results identified 185 (3198), 394 (3592), and 83 (3286) differentially expressed genes (transcripts) between tail and subcutaneous, tail and visceral, and subcutaneous and visceral adipose tissues, respectively. Functional annotation and pathway analysis revealed the following observations. (1) Among the differentially expressed genes (DEGs) of TF and SF tissues, the downregulation of ACADL, ACSL6, and NC_056060.1.2536 was observed in SF, while FFAR4 exhibited upregulation. (2) Among the DEGs of TF and VF tissues, expressions of ACADL, ACSL6, COL1A1, COL1A2, and SCD were downregulated in VF, with upregulation of FFAR4. (3) Among SF and VF expressions of COL1A1, COL1A2, and NC_056060.1.2536 were downregulated in VF. Specific differentially expressed genes (ACADL, ACSL6, COL1A1, COL1A2, FFAR4, NC_056060.1.2536, and SCD) and transcripts (NC_056066.1.1866.16 and NC_056066.1.1866.22) were identified as relevant to fat metabolism. These results provide a dataset for further verification of the regulatory pathway associated with fat metabolism in sheep.

Functional Food in Relation to Gastroesophageal Reflux Disease (GERD)

Gastroesophageal reflux disease (GERD) is a common esophageal disorder characterized by troublesome symptoms associated with increased esophageal acid exposure. The cornerstones of therapy in this regard include treatment with acid-suppressive agents, lifestyle modifications, and dietary therapy, although the latter has not been well defined. As concerns regarding long-term proton pump inhibitor (PPI) use continue to be explored, patients and healthcare providers are becoming increasingly interested in the role of diet in disease management. However, dietary interventions lack evidence of the synthesis effect of functional foods. The following is a review of dietary therapy for GERD, emphasizing food components' impact on GERD pathophysiology and management. Although the sequential dietary elimination of food groups is a common practice, the literature supports broader intervention, including reduced overall sugar intake, increased dietary fiber, and changes in overall eating practices. While the primary concern of food companies is to provide safe products, the caloric, nutritional, and functional composition of foods is also generating interest in the food industry due to consumers' concerns.

Lipid-Sensing Receptor FFAR4 Modulates Pulmonary Epithelial Homeostasis following Immunogenic Exposures Independently of the FFAR4 Ligand Docosahexaenoic Acid (DHA)

The role of pulmonary free fatty acid receptor 4 (FFAR4) is not fully elucidated and we aimed to clarify the impact of FFAR4 on the pulmonary immune response and return to homeostasis. We employed a known high-risk human pulmonary immunogenic exposure to extracts of dust from swine confinement facilities (DE). WT and Ffar4-null mice were repetitively exposed to DE via intranasal instillation and supplemented with docosahexaenoic acid (DHA) by oral gavage. We sought to understand if previous findings of DHA-mediated attenuation of the DE-induced inflammatory response are FFAR4-dependent. We identified that DHA mediates anti-inflammatory effects independent of FFAR4 expression, and that DE-exposed mice lacking FFAR4 had reduced immune cells in the airways, epithelial dysplasia, and impaired pulmonary barrier integrity. Analysis of transcripts using an immunology gene expression panel revealed a role for FFAR4 in lungs related to innate immune initiation of inflammation, cytoprotection, and immune cell migration. Ultimately, the presence of FFAR4 in the lung may regulate cell survival and repair following immune injury, suggestive of potential therapeutic directions for pulmonary disease.

α-Linolenic Acid Inhibits RANKL-Induced Osteoclastogenesis In Vitro and Prevents Inflammation In Vivo

Inflammation is an important risk factor for bone-destroying diseases. Our preliminary research found that Zanthoxylum bungeanum seed oil (ZBSO) is abundant in unsaturated fatty acids and could inhibit osteoclastogenesis in receptor activator of nuclear factor κB ligand (RANKL)-induced RAW264.7 cells. However, the key constituents in ZBSO in the prevention of osteoclastogenesis and its possible mechanism related to inflammation are still unclear. Therefore, in this study, oleic acid (OA), linoleic acid (LA), palmitoleic acid (PLA), and alpha-linolenic acid (ALA) in ZBSO, havingthe strongest effect on RANKL-induced osteoclastogenesis, were selected by a tartrate-resistant acid phosphatase (TRAP) staining method. Furthermore, the effects of the selected fatty acids on anti-inflammation and anti-osteoclastogenesis in vitro and in vivo were assessed using RT-qPCR. Among the four major unsaturated fatty acids we tested, ALA displayed the strongest inhibitory effect on osteoclastogenesis. The increased expression of free fatty acid receptor 4 (FFAR4) and β-arrestin2 (βarr2), as well as the decreased expression of nuclear factor-kappa B (NF-κB), tumor necrosis factor-α (TNF-α), nuclear factor of activated T-cells c1 (NFATc1), and tartrate-resistant acid phosphatase (TRAP) in RAW264.7 cells after ALA treatment were observed. Moreover, in ovariectomized osteoporotic rats with ALA preventive intervention, we found that the expression of TNF-α, interleukin-6 (IL-6), interleukin-1β (IL-1β), NFATc1, and TRAP were decreased, while with the ALA therapeutic intervention, downregulated expression of NF-κB, NFATc1, TRAP, and transforming growth factor beta-activated kinase 1 (TAK1) were noticed. These results indicate that ALA, as the major unsaturated fatty acid in ZBSO, could inhibit RANKL-induced osteoclastogenesis via the FFAR4/βarr2 signaling pathway and could prevent inflammation, suggesting that ZBSO may be a promising potential natural product of unsaturated fatty acids and a dietary supplement for the prevention of osteoclastogenesis and inflammatory diseases.

Immune regulation of poly unsaturated fatty acids and free fatty acid receptor 4

Fatty acid metabolism contributes to energy supply and plays an important role in regulating immunity. Free fatty acids (FFAs) bind to free fatty acid receptors (FFARs) on the cell surface and mediate effects through the intra-cellular FFAR signaling pathways. FFAR4, also known as G-protein coupled receptor 120 (GPR120), has been identified as the primary receptor of omega-3 polyunsaturated fatty acids (ω-3 PUFAs). FFAR4 is a promising target for treating metabolic and inflammatory disorders due to its immune regulatory functions and the discovery of highly selective and efficient agonists. This review summarizes the reported immune regulatory functions of ω-3 PUFAs and FFAR4 in immune cells and immune-related diseases. We also speculate possible involvements of ω-3 PUFAs and FFAR4 in other types of inflammatory disorders.

Genetic Modeling and Genomic Analyses of Yearling Temperament in American Angus Cattle and Its Relationship With Productive Efficiency and Resilience Traits

Cattle temperament has been considered by farmers as a key breeding goal due to its relevance for cattlemen's safety, animal welfare, resilience, and longevity and its association with many economically important traits (e.g., production and meat quality). The definition of proper statistical models, accurate variance component estimates, and knowledge on the genetic background of the indicator trait evaluated are of great importance for accurately predicting the genetic merit of breeding animals. Therefore, 266,029 American Angus cattle with yearling temperament records (1-6 score) were used to evaluate statistical models and estimate variance components; investigate the association of sex and farm management with temperament; assess the weighted correlation of estimated breeding values for temperament and productive, reproductive efficiency and resilience traits; and perform a weighted single-step genome-wide association analysis using 69,559 animals genotyped for 54,609 single-nucleotide polymorphisms. Sex and extrinsic factors were significantly associated with temperament, including conception type, age of dam, birth season, and additional animal-human interactions. Similar results were observed among models including only the direct additive genetic effect and when adding other maternal effects. Estimated heritability of temperament was equal to 0.39 on the liability scale. Favorable genetic correlations were observed between temperament and other relevant traits, including growth, feed efficiency, meat quality, and reproductive traits. The highest approximated genetic correlations were observed between temperament and growth traits (weaning weight, 0.28; yearling weight, 0.28). Altogether, we identified 11 genomic regions, located across nine chromosomes including BTAX, explaining 3.33% of the total additive genetic variance. The candidate genes identified were enriched in pathways related to vision, which could be associated with reception of stimulus and/or cognitive abilities. This study encompasses large and diverse phenotypic, genomic, and pedigree datasets of US Angus cattle. Yearling temperament is a highly heritable and polygenic trait that can be improved through genetic selection. Direct selection for temperament is not expected to result in unfavorable responses on other relevant traits due to the favorable or low genetic correlations observed. In summary, this study contributes to a better understanding of the impact of maternal effects, extrinsic factors, and various genomic regions associated with yearling temperament in North American Angus cattle.

Free fatty acid receptors in the endocrine regulation of glucose metabolism: Insight from gastrointestinal-pancreatic-adipose interactions

Glucose metabolism is primarily controlled by pancreatic hormones, with the coordinated assistance of the hormones from gastrointestine and adipose tissue. Studies have unfolded a sophisticated hormonal gastrointestinal-pancreatic-adipose interaction network, which essentially maintains glucose homeostasis in response to the changes in substrates and nutrients. Free fatty acids (FFAs) are the important substrates that are involved in glucose metabolism. FFAs are able to activate the G-protein coupled membrane receptors including GPR40, GPR120, GPR41 and GPR43, which are specifically expressed in pancreatic islet cells, enteroendocrine cells as well as adipocytes. The activation of FFA receptors regulates the secretion of hormones from pancreas, gastrointestine and adipose tissue to influence glucose metabolism. This review presents the effects of the FFA receptors on glucose metabolism via the hormonal gastrointestinal-pancreatic-adipose interactions and the underlying intracellular mechanisms. Furthermore, the development of therapeutic drugs targeting FFA receptors for the treatment of abnormal glucose metabolism such as type 2 diabetes mellitus is summarized.

Disproportionate Vitamin A Deficiency in Women of Specific Ethnicities Linked to Differences in Allele Frequencies of Vitamin A-Related Polymorphisms

Background: While the current national prevalence rate of vitamin A deficiency (VAD) is estimated to be less than 1%, it is suggested that it varies between different ethnic groups and races within the U.S. We assessed the prevalence of VAD in pregnant women of different ethnic groups and tested these prevalence rates for associations with the vitamin A-related single nucleotide polymorphism (SNP) allele frequencies in each ethnic group. Methods: We analyzed two independent datasets of serum retinol levels with self-reported ethnicities and the differences of allele frequencies of the SNPs associated with vitamin A metabolism between groups in publicly available datasets. Results: Non-Hispanic Black and Hispanic pregnant women showed high VAD prevalence in both datasets. Interestingly, the VAD prevalence for Hispanic pregnant women significantly differed between datasets (p = 1.973 × 10⁻¹⁰, 95%CI 0.04–0.22). Alleles known to confer the risk of low serum retinol (rs10882272 C and rs738409 G) showed higher frequencies in the race/ethnicity groups with more VAD. Moreover, minor allele frequencies of a set of 39 previously reported SNPs associated with vitamin A metabolism were significantly different between the populations of different ancestries than those of randomly selected SNPs (p = 0.030). Conclusions: Our analysis confirmed that VAD prevalence varies between different ethnic groups/races and may be causally associated with genetic variants conferring risk for low retinol levels. Assessing genetic variant information prior to performing an effective nutrient supplementation program will help us plan more effective food-based interventions.

Putting ATM to BED: How Adipose Tissue Macrophages Are Affected by Bariatric Surgery, Exercise, and Dietary Fatty Acids

With increasing adiposity in obesity, adipose tissue macrophages contribute to adipose tissue malfunction and increased circulating proinflammatory cytokines. The chronic low-grade inflammation that occurs in obesity ultimately gives rise to a state of metainflammation that increases the risk of metabolic disease. To date, only lifestyle and surgical interventions have been shown to be somewhat effective at reversing the negative consequences of obesity and restoring adipose tissue homeostasis. Exercise, dietary interventions, and bariatric surgery result in immunomodulation, and for some individuals their effects are significant with or without weight loss. Robust evidence suggests that these interventions reduce chronic inflammation, in part, by affecting macrophage infiltration and promoting a phenotypic switch from the M1- to M2-like macrophages. The purpose of this review is to discuss the impact of dietary fatty acids, exercise, and bariatric surgery on cellular characteristics affecting adipose tissue macrophage presence and phenotypes in obesity.

Anti-Atherosclerotic Potential of Free Fatty Acid Receptor 4 (FFAR4)

Fatty acids (FAs) are considered not only as a basic nutrient, but are also recognized as signaling molecules acting on various types of receptors. The receptors activated by FAs include the family of rhodopsin-like receptors: GPR40 (FFAR1), GPR41 (FFAR3), GPR43 (FFAR2), GPR120 (FFAR4), and several other, less characterized G-protein coupled receptors (GPR84, GPR109A, GPR170, GPR31, GPR132, GPR119, and Olfr78). The ubiquitously distributed FFAR4 can be activated by saturated and unsaturated medium- and long-chain fatty acids (MCFAs and LCFAs), as well as by several synthetic agonists (e.g., TUG-891). The stimulation of FFAR4 using selective synthetic agonists proved to be promising strategy of reduction of inflammatory reactions in various tissues. In this paper, we summarize the evidence showing the mechanisms of the potential beneficial effects of FFAR4 stimulation in atherosclerosis. Based partly on our own results, we also suggest that an important mechanism of such activity may be the modulatory influence of FFAR4 on the phenotype of macrophage involved in atherogenesis.

Odorant and Taste Receptors in Sperm Chemotaxis and Cryopreservation: Roles and Implications in Sperm Capacitation, Motility and Fertility

Sperm chemotaxis, which guide sperm toward oocyte, is tightly associated with sperm capacitation, motility, and fertility. However, the molecular mechanism of sperm chemotaxis is not known. Reproductive odorant and taste receptors, belong to G-protein-coupled receptors (GPCR) super-family, cause an increase in intracellular Ca²⁺ concentration which is pre-requisite for sperm capacitation and acrosomal reaction, and result in sperm hyperpolarization and increase motility through activation of Ca²⁺-dependent Cl^¯ channels. Recently, odorant receptors (ORs) in olfactory transduction pathway were thought to be associated with post-thaw sperm motility, freeze tolerance or freezability and cryo-capacitation-like change during cryopreservation. Investigation of the roles of odorant and taste receptors (TRs) is important for our understanding of the freeze tolerance or freezability mechanism and improve the motility and fertility of post-thaw sperm. Here, we reviewed the roles, mode of action, impact of odorant and taste receptors on sperm chemotaxis and post-thaw sperm quality.

Disrupted Lipid Raft Shuttling of FcεRI by n-3 Polyunsaturated Fatty Acid Is Associated With Ligation of G Protein-Coupled Receptor 120 (GPR120) in Human Mast Cell Line LAD2

n-3 polyunsaturated fatty acids (PUFA) influences a variety of disease conditions, such as hypertension, heart disease, diabetes, cancer and allergic diseases, by modulating membrane constitution, inhibiting production of proinflammatory eicosanoids and cytokines, and binding to cell surface and nuclear receptors. We have previously shown that n-3 PUFA inhibit mast cell functions by disrupting high affinity IgE receptor (FcεRI) lipid raft partitioning and subsequent suppression of FcεRI signaling in mouse bone marrow-derived mast cells. However, it is still largely unknown how n-3 PUFA modulate human mast cell function, which could be attributed to multiple mechanisms. Using a human mast cell line (LAD2), we have shown similar modulating effects of n-3 PUFA on FcεRI lipid raft shuttling, FcεRI signaling, and mediator release after cell activation through FcεRI. We have further shown that these effects are at least partially associated with ligation of G protein-coupled receptor 120 expressed on LAD2 cells. This observation has advanced our mechanistic knowledge of n-3 PUFA's effect on mast cells and demonstrated the interplay between n-3 PUFA, lipid rafts, FcεRI, and G protein-coupled receptor 120. Future research in this direction may present new targets for nutritional intervention and therapeutic agents.

The Role of Omega-3 Polyunsaturated Fatty Acids from Different Sources in Bone Development

N-3 polyunsaturated fatty acids (PUFAs) are essential nutrients that must be obtained from the diet. We have previously showed that endogenous n-3 PUFAs contribute to skeletal development and bone quality in fat-1 mice. Unlike other mammals, these transgenic mice, carry the n-3 desaturase gene and thus can convert n-6 to n-3 PUFAs endogenously. Since this model does not mimic dietary exposure to n-3 PUFAs, diets rich in fish and flaxseed oils were used to further elucidate the role of n-3 PUFAs in bone development. Our investigation reveals that dietary n-3 PUFAs decrease fat accumulation in the liver, lower serum fat levels, and alter fatty acid (FA) content in liver and serum. Bone analyses show that n-3 PUFAs improve mechanical properties, which were measured using a three-point bending test, but exert complex effects on bone structure that vary according to its source. In a micro-CT analysis, we found that the flaxseed oil diet improves trabecular bone micro-architecture, whereas the fish oil diet promotes higher bone mineral density (BMD) with no effect on trabecular bone. The transcriptome characterization of bone by RNA-seq identified regulatory mechanisms of n-3 PUFAs via modulation of the cell cycle and peripheral circadian rhythm genes. These results extend our knowledge and provide insights into the molecular mechanisms of bone remodeling regulation induced by different sources of dietary n-3 PUFAs.

Characterization of Free Fatty Acid Receptor 4 and Its Involvement in Nutritional Control and Immune Response in Pacific Oysters (Crassostrea gigas)

Free fatty acid receptor 4 (FFAR4) has various physiological functions, including energy regulation and immunological homeostasis. We examined the only FFAR4 homologue in the Pacific oyster Crassostrea gigas (CgFFAR4), which functions as a sensor of long-chain fatty acids. CgFFAR4 is 1098 bp long and contains a seven-transmembrane G protein-coupled receptor domain. CgFFAR4 expression was high in the hepatopancreas, but it was downregulated after fasting, indicating that it plays an essential role in food digestion. Lipopolysaccharide stimulation downregulated CgFFAR4 level, probably as an immune response of the animal. Reduced glycogen level alongside decreased insulin receptor, insulin receptor substrate, and C. gigas glycogen synthase transcription levels after CgFFAR4 knockdown revealed that CgFFAR4 was involved in the regulation of fatty acid and glycogen levels via the insulin pathway. Accordingly, this is the first study on an invertebrate FFAR and provides new insights into the role of this receptor in immune response and nutritional control.

Relationship between the effect of polyunsaturated fatty acids (PUFAs) on brain plasticity and the improvement on cognition and behavior in individuals with autism spectrum disorder

Objective: This work aimed to compile information about the neuronal processes in which polyunsaturated fatty acids (PUFAs) could modulate brain plasticity, in order to analyze the role of nutritional intervention with the ω-3 and ω-6 fatty acids as a therapeutic strategy for the Autism Spectrum Disorder (ASD)-related signs and symptoms.Methods: We reviewed different articles reporting the effect of PUFAS on neurite elongation, membrane expansion, cytoskeleton rearrangement and neurotransmission, considering the ASD-related abnormalities in these processes.Results: In accordance to the reviewed studies, it is clear that ASD is one of the neurological conditions associated with an impairment in neuronal plasticity; therefore, PUFAs-rich diet improvements on cognition and behavioral deficits in individuals with autism, could be involved with the regulation of neuronal processes implicated in the atypical brain plasticity related with this neurodevelopmental disorder.Discussion: The behavioral and cognitive improvement observed in individuals with ASD after PUFAs treatment might underlie, at least in part, in the ability of ω-3 and ω-6 fatty acids to induce neurite outgrowth, probably, through the dynamic regulation of the neuronal cytoskeleton along with the expansion of neuronal membranes. Furthermore, it might also be associated with an enhancement of the efficacy of synaptic transmission and the modulation of neurotransmitters release.

Eicosapentaenoic acid prevents the progression of intracranial aneurysms in rats

Background

As subarachnoid hemorrhage due to rupture of an intracranial aneurysm (IA) has quite a poor outcome despite of an intensive medical care, development of a novel treatment targeting unruptured IAs based on the correct understanding of pathogenesis is mandatory for social health.

Methods

Using previously obtained gene expression profile data from surgically resected unruptured human IA lesions, we selected G-protein coupled receptor 120 (GPR120) as a gene whose expression is significantly higher in lesions than that in control arterial walls. To corroborate a contribution of GPR120 signaling to the pathophysiology, we used an animal model of IAs and examine the effect of a GPR120 agonist on the progression of the disease. IA lesion was induced in rats through an increase of hemodynamic stress achieved by a one-sided carotid ligation and induced hypervolemia. Eicosapentaenoic acid (EPA) was used as an agonist for GPR120 in this study and its effect on the size of IAs, the thinning of media, and infiltration of macrophages in lesions were examined.

Result

EPA administered significantly suppressed the size of IAs and the degenerative changes in the media in rats. EPA treatment also inhibited infiltration of macrophages, a hallmark of inflammatory responses in lesions. In in vitro experiments using RAW264.7 cells, pre-treatment of EPA partially suppressed lipopolysaccharide-induced activation of nuclear factor-kappa B and also the transcriptional induction of monocyte chemoattractant protein 1 (MCP-1), a major chemoattractant for macrophages to accumulate in lesions. As a selective agonist of GPR120, TUG-891, could reproduce the effect of EPA in RAW264.7 cells, EPA presumably acted on this receptor to suppress inflammatory responses. Consistently, EPA remarkably suppressed MCP-1 expression in lesions, suggesting the in vivo relevance of in vitro studies.

Conclusions

These results combined together suggest the potential of the medical therapy targeting GPR120 or using EPA to prevent the progression of IAs.

New insights into the pathogenesis of leprosy: contribution of subversion of host cell metabolism to bacterial persistence, disease progression, and transmission

Chronic infection by the obligate intracellular pathogen Mycobacterium leprae may lead to the development of leprosy. Of note, in the lepromatous clinical form of the disease, failure of the immune system to constrain infection allows the pathogen to reproduce to very high numbers with minimal clinical signs, favoring transmission. The bacillus can modulate cellular metabolism to support its survival, and these changes directly influence immune responses, leading to host tolerance, permanent disease, and dissemination. Among the metabolic changes, upregulation of cholesterol, phospholipids, and fatty acid biosynthesis is particularly important, as it leads to lipid accumulation in the host cells (macrophages and Schwann cells) in the form of lipid droplets, which are sites of polyunsaturated fatty acid-derived lipid mediator biosynthesis that modulate the inflammatory and immune responses. In Schwann cells, energy metabolism is also subverted to support a lipogenic environment. Furthermore, effects on tryptophan and iron metabolisms favor pathogen survival with moderate tissue damage. This review discusses the implications of metabolic changes on the course of M. leprae infection and host immune response and emphasizes the induction of regulatory T cells, which may play a pivotal role in immune modulation in leprosy.

Prepartum fatty acid supplementation in sheep. IV. Effect of calcium salts with eicosapentaenoic acid and docosahexaenoic acid in the maternal and finishing diet on lamb liver and adipose tissue during the lamb finishing period1

The objective of this study was to evaluate the effects of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) supplementation to ewes during late gestation on finishing lamb liver and adipose tissue fatty acid (FA) profile and gene expression. Lambs born from ewes supplemented with Ca salts of EPA + DHA, or palm FA distillate (PFAD) high in palmitic and oleic acid at 0.39% DM during the last 50 d of gestation were used. Lambs were weaned at 61 d of age and adapted to a high concentrate diet for 1.5 mo. After adaptation, 74 lambs (28 pens) were blocked by sex and BW and used in a 2 × 2 factorial arrangement of treatments using the factors of dam supplementation (DS) and lamb supplementation (LS) of Ca salts of EPA + DHA or PFAD at 1.48% DM. Lambs were slaughtered after 42 d and liver and adipose tissue collected for FA and gene expression analysis. Liver concentrations of EPA and DHA were greater (P < 0.01) with LS of EPA + DHA vs. PFAD during the finishing period. In adipose tissue, a lamb × dam interaction was observed for EPA (P = 0.02) and DHA (P = 0.04); LS of EPA + DHA increased EPA and DHA, but the increase was greatest in lambs born from ewes supplemented with PFAD. No lamb × dam treatment interactions were observed for gene expression in liver tissue (P > 0.10). Hepatic mRNA abundance of hormone-sensitive lipase (HSL; P = 0.01) was greater in lambs born from EPA + DHA ewes vs. lambs from PFAD ewes. mRNA expression of stearoyl-CoA desaturase (P < 0.01), fatty acid synthase (P = 0.01), Δ5-desaturase (P < 0.01), and Δ6-desaturase (P < 0.01) were decreased in liver of EPA + DHA lambs. A significant lamb × dam diet interaction was observed for elongation of very long chain fatty acid 2 in adipose tissue (P = 0.01); lambs supplemented with the same FA as their dams had lower expression. Expression of HSL tended (P = 0.08) to be decreased in adipose of EPA + DHA lambs born from EPA + DHA ewes. The changes in mRNA expression suggest that lipogenesis decreased, and lipolysis increased in lamb liver with EPA + DHA vs. PFAD supplementation during the finishing period. In adipose tissue, changes suggest that lipogenesis decreased in lambs born from EPA + DHA supplemented dams and supplemented with EPA + DHA during the finishing period. In addition, these results suggest an interaction between supplementation of FA to dams during late gestation on lamb response of adipose tissue, but not liver, to FA supplementation during the finishing period.

Octacosanol and policosanol prevent high-fat diet-induced obesity and metabolic disorders by activating brown adipose tissue and improving liver metabolism

Brown adipose tissue (BAT) is an attractive therapeutic target for treating obesity and metabolic diseases. Octacosanol is the main component of policosanol, a mixture of very long chain aliphatic alcohols obtained from plants. The current study aimed to investigate the effect of octacosanol and policosanol on high-fat diet (HFD)-induced obesity. Mice were fed on chow, or HFD, with or without octacosanol or policosanol treatment for four weeks. HFD-fed mice showed significantly higher body weight and body fat compared with chow-fed mice. However, mice fed on HFD treated with octacosanol or policosanol (HFDo/p) showed lower body weight gain, body fat gain, insulin resistance and hepatic lipid content. Lower body fat gain after octacosanol or policosanol was associated with increased BAT activity, reduced expression of genes involved in lipogenesis and cholesterol uptake in the liver, and amelioration of white adipose tissue (WAT) inflammation. Moreover, octacosanol and policosanol significantly increased the expression of Ffar4, a gene encoding polyunsaturated fatty acid receptor, which activates BAT thermogenesis. Together, these results suggest that octacosanol and policosanol ameliorate diet-induced obesity and metabolic disorders by increasing BAT activity and improving hepatic lipid metabolism. Thus, these lipids represent promising therapeutic targets for the prevention and treatment of obesity and obesity-related metabolic disorders.

The Nematode Caenorhabditis elegans as a Model Organism to Study Metabolic Effects of ω-3 Polyunsaturated Fatty Acids in Obesity

Obesity is a complex disease that is influenced by several factors, such as diet, physical activity, developmental stage, age, genes, and their interactions with the environment. Obesity develops as a result of expansion of fat mass when the intake of energy, stored as triglycerides, exceeds its expenditure. Approximately 40% of the US population suffers from obesity, which represents a worldwide public health problem associated with chronic low-grade adipose tissue and systemic inflammation (sterile inflammation), in part due to adipose tissue expansion. In patients with obesity, energy homeostasis is further impaired by inflammation, oxidative stress, dyslipidemia, and metabolic syndrome. These pathologic conditions increase the risk of developing other chronic diseases including diabetes, hypertension, coronary artery disease, and certain forms of cancer. It is well documented that several bioactive compounds such as omega-3 polyunsaturated fatty acids (ω-3 PUFAs) are able to reduce adipose and systemic inflammation and blood triglycerides and, in some cases, improve glucose intolerance and insulin resistance in vertebrate animal models of obesity. A promising model organism that is gaining tremendous interest for studies of lipid and energy metabolism is the nematode Caenorhabditis elegans. This roundworm stores fats as droplets within its hypodermal and intestinal cells. The nematode's transparent skin enables fat droplet visualization and quantification with the use of dyes that have affinity to lipids. This article provides a review of major research over the past several years on the use of C. elegans to study the effects of ω-3 PUFAs on lipid metabolism and energy homeostasis relative to metabolic diseases.

Extracorporeal shockwave against inflammation mediated by GPR120 receptor in cyclophosphamide-induced rat cystitis model

BACKGROUND

We tested the hypothesis that extracorporeal shockwave treatment (ESWT) can abolish inflammation and restore urothelial barrier integrity in acute interstitial cystitis by upregulating the fatty acid receptor GPR120.

METHODS

A total of 30 female Sprague-Dawley rats were categorized into five groups: (1) sham-operated rats (SC); (2) rats treated with ESWT (SC + ESWT); (3) rats with bladder irritation using 150 mg/kg cyclophosphamide through intraperitoneal injection; (4) cyclophosphamide rats treated with ESWT (cyclophosphamide+ESWT); (5) cyclophosphamide rats treated with GPR120 agonist (cyclophosphamide+GW9508).

RESULTS

On Day 3, urine and bladder specimens were collected for biochemical, histopathological, immunological, and immunoblotting analysis. Following stimulation with cyclophosphamide, the inhibition of the elevated levels of TAK1/NF-κB and phospho-TAK1/NF-κB by ESWT and GPR120 agonists in RT4 cells was associated with a suppression of NF-κB translocation from the cytosol to the nucleus. Accordingly, this anti-inflammatory effect was abolished by GPR120 antagonist and knockdown of GPR120. Histologically, bladder inflammation in cyclophosphamide-treated rats was suppressed by GW9508 or ESWT. Masson's trichrome and Sirius red staining revealed that cyclophosphamide treatment enhanced synthesis of extracellular matrix in rats that was reversed by GW9508 or ESWT. Upregulated pro-inflammatory mediators and cytokines in the cyclophosphamide-treated rats were also suppressed in the GW9508- or ESWT-treated rats. The significantly increased inflammatory cell infiltration as well as the impaired urothelial integrity of the bladder after cyclophosphamide treatment were reversed by treatment with GW9508 or ESWT.

CONCLUSIONS

These findings suggest that GPR120, the sensing receptor for ESWT, may be useful in the treatment of interstitial cystitis by inhibiting inflammatory response in bladder cells.

Prepartum fatty acid supplementation in sheep. II. Supplementation of eicosapentaenoic acid and docosahexaenoic acid during late gestation alters the fatty acid profile of plasma, colostrum, milk and adipose tissue, and increases lipogenic gene expression of adipose tissue

The objectives of this study were as follows: 1) to establish whether feeding a source of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) to ewes during late gestation changes the fatty acid profile of colostrum, milk, ewe adipose tissue, and plasma and subsequently lamb plasma and red blood cells (RBC), and 2) to investigate the effects of EPA and DHA on mRNA expression in ewe adipose tissue. Eighty-four gestating ewes (28 pens, three per pen) were blocked by lambing day and assigned to a diet with an addition of fat at 0.39% of the DM during the last 50 d of gestation using Ca salts of a palm fatty acid distillate (PFAD) high in palmitic and oleic acids or EPA + DHA. Blood samples were taken from ewes on days 20, 1 (parturition), and 30 and from lambs on days 1 and 30 for plasma fatty acid analysis. Fatty analysis of lamb RBC was performed on day 1. Colostrum samples were taken at lambing and milk samples on day 30 for fatty acid analysis. Subcutaneous adipose tissue biopsies were taken from one ewe per pen on day 20 for fatty acid analysis and gene expression analysis of 27 genes. Treatment × day interactions (P < 0.10) were observed for several isomers of C18:1, with concentrations that were greater in plasma of EPA + DHA ewes on day 20, but were not different on day 1 or 30. Plasma concentrations of EPA tended to be greater (P = 0.07), whereas DHA was greater (P < 0.001) in EPA + DHA ewes compared with PFAD ewes. There was no difference in EPA or DHA in adipose tissue with EPA + DHA vs. PFAD supplementation (P > 0.10). Concentrations of fatty acids with 6 to 10 carbons were significantly increased (P < 0.05) in colostrum and milk of EPA + DHA ewes. There was a treatment × day interaction with EPA + DHA ewes yielding greater EPA (P = 0.03) and DHA (P = 0.04) concentrations than PFAD in colostrum, but not in milk. Treatment × day interactions (P < 0.05) were observed for several C18:1 isomers with concentrations that were greater in EPA + DHA ewe colostrum, but were not different between treatments in milk. In lamb plasma and RBC, EPA and DHA were not different between treatments (P > 0.10). The expression of fatty acid synthase and leptin was significantly increased (P < 0.05), whereas the expression of diacylglycerol acyltransferase 2 tended to be increased (P = 0.08) by supplementation of EPA + DHA vs. PFAD. These results suggest that supplementation with EPA and DHA to ewes during late gestation alters the fatty acid profile of plasma, colostrum, and milk and may increase lipogenesis.

Polymorphisms in FFAR4 (GPR120) Gene Modulate Insulin Levels and Sensitivity after Fish Oil Supplementation

The objective was to test whether FFAR4 single nucleotide polymorphisms (SNPs) are associated with glycemic control-related traits in humans following fish oil supplementation. A total of 210 participants were given 3 g/day of omega-3 (n-3) fatty acids (FA) (1.9–2.2 g of eicosapentaenoic acid (EPA) and 1.1 g of docosahexaenoic acid (DHA)) during six weeks. Biochemical parameters were taken before and after the supplementation. Using the HapMap database and the tagger procedure in Haploview, 12 tagging SNPs in FFAR4 were selected and then genotyped using TaqMan technology. Transcript expression levels were measured for 30 participants in peripheral mononuclear blood cells. DNA methylation levels were measured for 35 participants in leukocytes. In silico analyses were also performed. Four gene–diet interactions on fasting insulin levels and homeostatic model assessment of insulin resistance (HOMA-IR) index values were found. rs17108973 explained a significant proportion of the variance of insulin levels (3.0%) and HOMA-IR (2.03%) index values. Splice site prediction was different depending on the allele for rs11187527. rs17108973 and rs17484310 had different affinity for transcription factors depending on the allele. n-3 FAs effectively improve insulin-related traits for major allele homozygotes of four FFAR4 SNPs as opposed to carriers of the minor alleles.

Free Fatty Acid Receptors and Cancer: From Nutrition to Pharmacology

The effects of fatty acids on cancer cells have been studied for decades. The roles of dietary long-chain n-3 polyunsaturated fatty acids, and of microbiome-generated short-chain butyric acid, have been of particular interest over the years. However, the roles of free fatty acid receptors (FFARs) in mediating effects of fatty acids in tumor cells have only recently been examined. In reviewing the literature, the data obtained to date indicate that the long-chain FFARs (FFA1 and FFA4) play different roles than the short-chain FFARs (FFA2 and FFA3). Moreover, FFA1 and FFA4 can in some cases mediate opposing actions in the same cell type. Another conclusion is that different types of cancer cells respond differently to FFAR activation. Currently, the best-studied models are prostate, breast, and colon cancer. FFA1 and FFA4 agonists can inhibit proliferation and migration of prostate and breast cancer cells, but enhance growth of colon cancer cells. In contrast, FFA2 activation can in some cases inhibit proliferation of colon cancer cells. Although the available data are sometimes contradictory, there are several examples in which FFAR agonists inhibit proliferation of cancer cells. This is a unique response to GPCR activation that will benefit from a mechanistic explanation as the field progresses. The development of more selective FFAR agonists and antagonists, combined with gene knockout approaches, will be important for unraveling FFAR-mediated inhibitory effects. These inhibitory actions, mediated by druggable GPCRs, hold promise for cancer prevention and/or therapy.