Excitatory amino acid transporter supports inflammatory macrophage responses.

Excitatory amino acid transporters (EAATs) are responsible for excitatory amino acid transportation and are associated with auto-immune diseases in the central nervous system and peripheral tissues. However, the subcellular location and function of EAAT2 in macrophages are still obscure. In this study, we demonstrated that LPS stimulation increases expression of EAAT2 (coded by Slc1a2) via NF-κB signaling. EAAT2 is necessary for inflammatory macrophage polarization through sustaining mTORC1 activation. Mechanistically, lysosomal EAAT2 mediates lysosomal glutamate and aspartate efflux to maintain V-ATPase activation, which sustains macropinocytosis and mTORC1. We also found that mice with myeloid depletion of Slc1a2 show alleviated inflammatory responses in LPS-induced systemic inflammation and high-fat diet induced obesity. Notably, patients with type II diabetes (T2D) have a higher level of expression of lysosomal EAAT2 and activation of mTORC1 in blood macrophages. Taken together, our study links the subcellular location of amino acid transporters with the fate decision of immune cells, which provides potential therapeutic targets for the treatment of inflammatory diseases.

Serine synthesis sustains macrophage IL-1ß production via NAD+-dependent protein acetylation.

Serine metabolism is involved in the fate decisions of immune cells; however, whether and how de novo serine synthesis shapes innate immune cell function remain unknown. Here, we first demonstrated that inflammatory macrophages have high expression of phosphoglycerate dehydrogenase (PHGDH, the rate-limiting enzyme of de novo serine synthesis) via nuclear factor κB signaling. Notably, the pharmacological inhibition or genetic modulation of PHGDH limits macrophage interleukin (IL)-1ß production through NAD+ accumulation and subsequent NAD+-dependent SIRT1 and SIRT3 expression and activity. Mechanistically, PHGDH not only sustains IL-1ß expression through H3K9/27 acetylation-mediated transcriptional activation of Toll-like receptor 4 but also supports IL-1ß maturation via NLRP3-K21/22/24/ASC-K21/22/24 acetylation-mediated activation of the NLRP3 inflammasome. Moreover, mice with myeloid-specific depletion of Phgdh show alleviated inflammatory responses in lipopolysaccharide-induced systemic inflammation. This study reveals a network by which a metabolic enzyme, involved in de novo serine synthesis, mediates post-translational modifications and epigenetic regulation to orchestrate IL-1ß production, providing a potential inflammatory disease target.

Carbon metabolism in the regulation of macrophage functions.

Carbon metabolism, including one-carbon (1C) metabolism and central carbon metabolism (CCM), provides energy for the cell and generates metabolites with signaling activities. The regulation of macrophage polarization involves complex signals and includes an epigenetic level. Epigenetic modifications through changes in carbon metabolism allow macrophages to respond in a timely manner to their environment and adapt to metabolic demands during macrophage polarization. Here we summarize the current understanding of the crosstalk between carbon metabolism and epigenetic modifications in macrophages under physiological conditions and in the tumor microenvironment (TME) and provide targets and further directions for macrophage-associated diseases.

Gut microbiota bridges dietary nutrients and host immunity.

Dietary nutrients and the gut microbiota are increasingly recognized to cross-regulate and entrain each other, and thus affect host health and immune-mediated diseases. Here, we systematically review the current understanding linking dietary nutrients to gut microbiota-host immune interactions, emphasizing how this axis might influence host immunity in health and diseases. Of relevance, we highlight that the implications of gut microbiota-targeted dietary intervention could be harnessed in orchestrating a spectrum of immune-associated diseases.

Transcriptional and Post-Transcriptional Regulation of Autophagy.

Autophagy is a widely conserved process in eukaryotes that is involved in a series of physiological and pathological events, including development, immunity, neurodegenerative disease, and tumorigenesis. It is regulated by nutrient deprivation, energy stress, and other unfavorable conditions through multiple pathways. In general, autophagy is synergistically governed at the RNA and protein levels. The upstream transcription factors trigger or inhibit the expression of autophagy- or lysosome-related genes to facilitate or reduce autophagy. Moreover, a significant number of non-coding RNAs (microRNA, circRNA, and lncRNA) are reported to participate in autophagy regulation. Finally, post-transcriptional modifications, such as RNA methylation, play a key role in controlling autophagy occurrence. In this review, we summarize the progress on autophagy research regarding transcriptional regulation, which will provide the foundations and directions for future studies on this self-eating process.

Glycinergic Signaling in Macrophages and Its Application in Macrophage-Associated Diseases.

Accumulating evidences support that amino acids direct the fate decision of immune cells. Glycine is a simple structural amino acid acting as an inhibitory neurotransmitter. Besides, glycine receptors as well as glycine transporters are found in macrophages, indicating that glycine alters the functions of macrophages besides as an inhibitory neurotransmitter. Mechanistically, glycine shapes macrophage polarization via cellular signaling pathways (e.g., NF-κB, NRF2, and Akt) and microRNAs. Moreover, glycine has beneficial effects in preventing and/or treating macrophage-associated diseases such as colitis, NAFLD and ischemia-reperfusion injury. Collectively, this review highlights the conceivable role of glycinergic signaling for macrophage polarization and indicates the potential application of glycine supplementation as an adjuvant therapy in macrophage-associated diseases.

Dietary dihydroartemisinin supplementation alleviates intestinal inflammatory injury through TLR4/NOD/NF-κB signaling pathway in weaned piglets with intrauterine growth retardation.

The aim of present study was to evaluate whether diets supplemented with dihydroartemisinin (DHA) could alleviate intestinal inflammatory injury in weaned piglets with intrauterine growth retardation (IUGR). Twelve normal birth weight (NBW) piglets and 12 piglets with IUGR were fed a basal diet (NBW-CON and IUCR-CON groups), and another 12 piglets with IUGR were fed the basal diet supplemented with DHA at 80 mg/kg (IUGR-DHA group) from 21 to 49 d of age. At 49 d of age, 8 piglets with similar body weight in each group were sacrificed. The jejunal and ileal samples were collected for further analysis. The results showed that IUGR impaired intestinal morphology, increased intestinal inflammatory response, raised enterocyte apoptosis and reduced enterocyte proliferation and activated transmembrane toll-like receptor 4 (TLR4)/nucleotide-binding and oligomerization domain (NOD)/nuclear factor-κB (NF-κB) signaling pathway. Dihydroartemisinin inclusion ameliorated intestinal morphology, indicated by increased villus height, villus height-to-crypt depth ratio, villus surface area and decreased villus width of piglets with IUGR (P < 0.05). Compared with NBW piglets, IUGR piglets supplemented with DHA exhibited higher apoptosis index and caspase-3 expression, and lower proliferation index and proliferating cell nuclear antigen expression in the intestine (P < 0.05). Dihydroartemisinin supplementation attenuated the intestinal inflammation of piglets with IUGR, indicated by increased concentrations of intestinal inflammatory cytokines and lipopolysaccharides (P < 0.05). In addition, DHA supplementation down-regulated the related mRNA expressions of TLR4/NOD/NF-κB signaling pathway and upregulated mRNA expressions of negative regulators of TLR4 and NOD signaling pathway in the intestine of piglets with IUGR (P < 0.05). Piglets in the IUGR-DHA group showed lower protein expressions of TLR4, phosphorylated NF-κB (pNF-κB) inhibitor α, nuclear pNF-κB, and higher protein expression of cytoplasmic pNF-κB in the intestine than those in the IUGR-CON group (P < 0.05). In conclusion, DHA supplementation could improve intestinal morphology, regulate enterocyte proliferation and apoptosis, and alleviate intestinal inflammation through TLR4/NOD/NF-κB signaling pathway in weaned piglets with IUGR.

Effect of Vitamin E Supplementation on Deposition and Gene Expression Profiling of Abdominal Fat in Broiler Chickens.

The aim of this study was to study the regulation of abdominal fat deposition by DL-α-tocopherol acetate (vitamin E) in broilers. Diets supplemented with 50 IU vitamin E significantly diminished abdominal fat deposition in broilers at day 35. Transcriptome sequencing results for abdominal fat tissues of the control (FC) and 50 IU vitamin E-supplemented (FT) groups identified 602 differentially expressed genes (DEGs), which were enriched in cellular process, cell and cell part, and binding Gene Ontology terms. Pathway functional analysis revealed that the DEGs were enriched in 42 metabolic pathways. Notably, the most enriched pathway, fatty acid biosynthesis, was found to play a key role in lipid metabolism. Further, the key regulators of lipid metabolism, including fatty acid synthase, acetyl-CoA carboxylase alpha, and acyl-CoA synthetase long-chain family member 1, demonstrated decreased expression following vitamin E supplementation. Herein, we have identified pathways and genes regulated by vitamin E, thereby providing novel insights into the nutrients regulating abdominal fat deposition in broilers.

Resveratrol Attenuates Aflatoxin B1-Induced ROS Formation and Increase of m6A RNA Methylation.

Aflatoxin B1 (AFB1) is one of the most dangerous mycotoxins in both humans and animals. Regulation of resveratrol is essential for the inhibition of AFB1-induced oxidative stress and liver injury. Whether N6-methyladenosine (m6A) mRNA methylation participates in the crosstalk between resveratrol and AFB1 is unclear. The objective of this study was to investigate the effects of AFB1 and resveratrol in m6A RNA methylation and their crosstalk in the regulation of hepatic function in mice. Thirty-two C57BL/6J male mice were randomly assigned to a CON (basal diet), RES (basal diet + 500 mg/kg resveratrol), AFB1 (basal diet + 600 µg/kg aflatoxin B1), and ARE (basal diet + 500 mg/kg resveratrol and 600 µg/kg aflatoxin B1) group for 4 weeks of feeding (n = 8/group). Briefly, redox status, apoptosis, and m6A modification in the liver were assessed. Compared to the CON group, the AFB1 group showed increased activities of serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT), prevalent vacuolization and cell edema, abnormal redox status, imbalance apoptosis, and especially, the higher expression of cleaved-caspase-3 protein. On the contrary, resveratrol ameliorated adverse hepatic function, via increasing hepatic antioxidative capacity and inhibiting the expression of cleaved-caspase-3 protein. Importantly, we noted that reactive oxygen species (ROS) content could be responsible for the alterations of m6A modification. Compared to the CON group, the AFB1 group elevated the ROS accumulation, which led to the augment in m6A modification, whereas dietary resveratrol supplementation decreased ROS, followed by the reduction of m6A levels. In conclusion, our findings indicated that resveratrol decreased AFB1-induced ROS accumulation, consequently contributing to the alterations of m6A modification, and eventually impacting on the hepatic function.

Effects of dietary dihydroartemisinin supplementation on growth performance, hepatic inflammation, and lipid metabolism in weaned piglets with intrauterine growth retardation.

The aims of this study were to investigate the effects of dietary supplementation with dihydroartemisinin (DHA) on growth performance, hepatic inflammation, and lipid metabolism in intrauterine growth retardation (IUGR)-affected weaned piglets. Eight piglets with normal birth weight (NBW) and 16 IUGR-affected piglets were selected and fed either a basal diet (NBW and IUGR groups) or the basal diet supplemented with 80 mg/kg DHA (IUGR-DHA group) from 21 to 49 day of age. Blood and liver samples were collected on day 49. DHA supplementation significantly alleviated the compromised growth performance and liver damage in IUGR-affected piglets. Additionally, DHA supplementation decreased the activities of alanine aminotransferase and aspartate aminotransferase, as well as the serum levels of non-esterified fatty acids (NEFA), very-low-density lipoprotein, and total cholesterol. In the liver, the concentrations of interleukin 1 beta, interleukin 6, tumor necrosis factor alpha, triglycerides, and NEFA were decreased. Fatty acid synthesis was decreased by DHA supplementation, whereas the activities of lipoprotein lipase, hepatic lipase, and total lipase were increased. Dietary DHA supplementation led to upregulation of the expression of AMPK/SIRT1 signaling pathway-related genes, whereas that of inflammatory factor-related genes were downregulated. In conclusion, dietary inclusion of 80 mg/kg DHA can alleviate IUGR-induced impairments in piglets.

Resveratrol Attenuates High-Fat Diet Induced Hepatic Lipid Homeostasis Disorder and Decreases m6A RNA Methylation.

Purpose: N 6-methyladenosine (m6A) mRNA methylation is affected by dietary factors and associated with lipid metabolism; however, whether the regulatory role of resveratrol in lipid metabolism is involved in m6A mRNA methylation remains unknown. Here, the objective of this study was to investigate the effect of resveratrol on hepatic lipid metabolism and m6A RNA methylation in the liver of mice. Methods: A total of 24 male mice were randomly allocated to LFD (low-fat diet), LFDR (low-fat diet + resveratrol), HFD (high-fat diet), and HFDR (high-fat diet + resveratrol) groups for 12 weeks (n = 6/group). Final body weight of mice was measured before sacrificing. Perirhemtric fat, abdominal and epididymal fat, liver tissues, and serum were collected at sacrifice and analyzed. Briefly, mice phenotype, lipid metabolic index, and m6A modification in the liver were assessed. Results: Compared to the HFD group, dietary resveratrol supplementation reduced the body weight and relative abdominal, epididymal, and perirhemtric fat weight in high-fat-exposed mice; however, resveratrol significantly increased average daily feed intake in mice given HFD. The amounts of serum low-density lipoprotein cholesterol (LDL), liver total cholesterol (TC), and triacylglycerol (TAG) were significantly decreased by resveratrol supplementation. In addition, resveratrol significantly enhanced the levels of peroxisome proliferator-activated receptor alpha (PPARα), peroxisome proliferator-activated receptor beta/delta (PPARß/δ), cytochrome P450, family 4, subfamily a, polypeptide 10/14 (CYP4A10/14), acyl-CoA oxidase 1 (ACOX1), and fatty acid-binding protein 4 (FABP4) mRNA and inhibited acyl-CoA carboxylase (ACC) mRNA levels in the liver. Furthermore, the resveratrol in HFD increased the transcript levels of methyltransferase like 3 (METTL3), alkB homolog 5 (ALKBH5), fat mass and obesity associated protein (FTO), and YTH domain family 2 (YTHDF2), whereas it decreased the level of YTH domain family 3 (YTHDF3) and m6A abundance in mice liver. Conclusion: The beneficial effect of resveratrol on lipid metabolism disorder under HFD may be due to decrease of m6A RNA methylation and increase of PPARα mRNA, providing mechanistic insights into the function of resveratrol in alleviating the disturbance of lipid metabolism in mice.

Emerging role of m6 A RNA methylation in nutritional physiology and metabolism.

N6 -methyladenine (m6 A) is the most prevalent type of internal RNA methylation in eukaryotic mRNA and plays critical roles in regulating gene expression for fundamental cellular processes and diverse physiological functions. Recent evidence indicates that m6 A methylation regulates physiology and metabolism, and m6 A has been increasingly implicated in a variety of human diseases, including obesity, diabetes, metabolic syndrome and cancer. Conversely, nutrition and diet can modulate or reverse m6 A methylation patterns on gene expression. In this review, we summarize the recent progress in the study of the m6 A methylation mechanisms and highlight the crosstalk between m6 A modification, nutritional physiology and metabolism.

Curcumin Alleviates IUGR Jejunum Damage by Increasing Antioxidant Capacity through Nrf2/Keap1 Pathway in Growing Pigs.

The purpose of this study was to explore the effects of curcumin on IUGR jejunum damage. A total of 24 IUGR and 12 normal-birth weight (NBW) female crossbred (Duroc × Landrace × Large White) piglets were randomly assigned into three groups at weaning (26 days): IUGR group, NBW group, and IUGR + CUR group, which were fed diets containing 0 mg/kg (NBW), 0 mg/kg (IUGR) and 200 mg/kg (IUGR + CUR) curcumin from 26 to 115 days of age. Results showed that dietary supplementation with 200 mg/kg curcumin significantly increased the total superoxide dismutase (T-SOD) activity and decreased the malondialdehyde (MDA) content in the jejunum of IUGR pigs (p < 0.05). Results of real-time PCR showed that the IUGR + CUR group significantly increased the gene expression of NF-E2-related factor 2 (Nrf2) (p < 0.05), and increased the glutamate-cysteine ligase catalytic subunit (GCLC), superoxide dismutase 1 (SOD1), glutamate-cysteine ligase modifier subunit (GCLM), and NAD(P)H quinone dehydrogenase 1 (NQO1) mRNA expression compared with the IUGR group (p < 0.05). Western blot results showed that dietary supplementation with 200 mg/kg curcumin significantly increased the protein levels of Nrf2 and NQO1. Compared with the IUGR group, pigs in IUGR + CUR group showed significantly decreased the levels of tumor necrosis factor-α (TNFα), interleukin-6 (IL-6), and interferon gamma (IFNγ) (p < 0.05), and increased the interleukin-2 (IL-2) level (p < 0.05). Dietary supplementation with 200 mg/kg curcumin significantly reduced cysteinyl aspartate specific proteinase 3 (caspase3), BCL2-associated X protein (bax), B-cellCLL/lymphoma 2 (bcl2), and heat-shock protein 70 (hsp70) mRNA expression, and increased occludin (ocln) mRNA expression (p < 0.05). In conclusion, dietary supplementation with 200 mg/kg curcumin can alleviate jejunum damage in IUGR growing pigs, through Nrf2/Keap1 pathway.

Dietary Curcumin Supplementation Increases Antioxidant Capacity, Upregulates Nrf2 and Hmox1 Levels in the Liver of Piglet Model with Intrauterine Growth Retardation.

Curcumin has improved effects on antioxidant capacity via multiple mechanisms. Intrauterine growth retardation (IUGR) has had adverse influences on human health. IUGR is always associated with elevated oxidative stress and deficiencies in antioxidant defense. Therefore, we chose IUGR piglets as a model to investigate the effects of IUGR on antioxidant capacity of newborn and weaned piglets and determine how these alterations were regulated after supplementation with curcumin in weaned IUGR piglets. In experiment 1, eight normal-birth-weight (NBW) and eight IUGR newborn piglets were selected to determine the effect of IUGR on the antioxidant capacity of neonatal piglets. In experiment 2, thirty-two weaned piglets from four experimental groups: NBW, NC (curcumin supplementation), IUGR, IC (curcumin supplementation) were selected. The results showed that both IUGR newborn and weaned piglets exhibited oxidative damage and lower antioxidant enzymes activities in the liver compared with the NBW piglets. Dietary curcumin supplementation increased body-weight gain, feed intake, activities of antioxidant enzymes, and the expressions of nuclear factor, erythroid 2-like 2 (Nrf2) and heme oxygenase-1 (Hmox1) proteins in the liver of weaned piglets with IUGR. In conclusion, IUGR decreased the antioxidant capacity of newborn and weaned piglets. Curcumin could efficiently improve the growth, increase hepatic antioxidant capacity, and upregulate Nrf2 and Hmox1 levels in the liver of IUGR weaned piglets.

Resveratrol and Curcumin Improve Intestinal Mucosal Integrity and Decrease m6A RNA Methylation in the Intestine of Weaning Piglets.

N 6-Methyladenosine (m6A) is the most prevalent modification on eukaryotic messenger RNA (mRNA). Resveratrol and curcumin, which can exert many health-protective effects, may have a relationship with m6A RNA methylation. We hypothesized that the combination of resveratrol and curcumin could affect growth performance, intestinal mucosal integrity, m6A RNA methylation, and gene expression in weaning piglets. One hundred and eighty piglets weaned at 28 ± 2 days were fed a control diet or supplementary diets (300 mg/kg of antibiotics; 300 mg/kg of each resveratrol and curcumin; 100 mg/kg of each resveratrol and curcumin; 300 mg/kg of resveratrol; 300 mg/kg of curcumin) for 28 days. The results showed that the combination of resveratrol and curcumin improved growth performance and enhanced intestinal mucosal integrity and functions in weaning piglets. Resveratrol and curcumin also increased intestinal antioxidative capacity and mRNA expression of tight junction proteins. Furthermore, resveratrol and curcumin decreased the content of m6A and decreased the enrichment of m6A on the transcripts of tight junction proteins and on heme oxygenase-1 in the intestine. Our findings indicated that the combination of resveratrol and curcumin increased growth performance, enhanced intestine function, and protected piglet health, which may be associated with changes in m6A methylation and gene expression, suggesting that curcumin and resveratrol may be a potential natural alternative to antibiotics.

Curcumin and Resveratrol Regulate Intestinal Bacteria and Alleviate Intestinal Inflammation in Weaned Piglets.

Human infants or piglets are vulnerable to intestinal microbe-caused disorders and inflammation due to their rapidly changing gut microbiota and immaturity of their immune systems at weaning. Resveratrol and curcumin have significant anti-inflammatory, bacteria-regulating and immune-promoting effects. The purpose of this study was to investigate whether dietary supplementation with resveratrol and curcumin can change the intestinal microbiota and alleviate intestinal inflammation induced by weaning in piglets. One hundred eighty piglets weaned at 21 ± 2 d were fed a control diet (CON group) or supplemented diet (300 mg/kg of antibiotics, ANT group; 300 mg/kg of resveratrol and curcumin, respectively, HRC group; 100 mg/kg of resveratrol and curcumin, respectively, LRC group; 300 mg/kg of resveratrol, RES group; 300 mg/kg of curcumin, CUR group) for 28 days. The results showed that compared with the CON group, curcumin alone and antibiotics decreased the copy numbers of Escherichia coli. Both curcumin and resveratrol down-regulated the level of Toll-like-receptor 4 mRNA and protein expression in the intestine to inhibit the release of critical inflammation molecules (interleukin-1ß, tumor necrosis factor-α), and increase the secretion of immunoglobulin. Our results suggested that curcumin and resveratrol can regulate weaned piglet gut microbiota, down-regulate the TLR4 signaling pathway, alleviate intestinal inflammation, and ultimately increase intestinal immune function.