Nur77 as a novel regulator of Paneth cell differentiation and function.

Serving as a part of intestinal innate immunity, Paneth cells plays an important role in intestinal homeostasis maintenance via their multiple functions. However, the regulation of Paneth cells has been proved to be complex and diverse. Here, we identified nuclear receptor Nur77 as a novel regulator of Paneth cell differentiation and function. Nur77 deficiency led to the loss of Paneth cells in murine ileal crypts. Intestinal tissues or organoids with Nur77 deficiency exhibited the impaired intestinal stem cell (ISC) niche and failed to enhance antimicrobial peptide (AMP) expression after Paneth cell degranulation. The defects in Paneth cells and AMPs in Nur77-/- mice led to intestinal microbiota disorders. Nur77 deficiency rendered postnatal mice susceptible to necrotizing enterocolitis (NEC). Mechanistically, Nur77 transcriptionally inhibited Dact1 expression to activate Wnt signaling activity, thus promoting Paneth cell differentiation and function. Taken together, our data suggest the regulatory role of Nur77 in Paneth cell differentiation and function and reveal a novel Dact1-mediated Wnt inhibition mechanism in Paneth cell development.

Paneth cells protect intestinal stem cell niche to alleviate deoxynivalenol-induced intestinal injury.

Deoxynivalenol (DON) is a common toxin in grains and feeds, and DON exposure triggers severe small intestinal injury and inflammation, which harms the health of humans and livestock. DON treatment leads to a decrease in Paneth cells, whereas the role of Paneth cells in DON-induced intestinal injury is poorly understood. We utilized dithizone (40 mg/kg) to keep murine Paneth cell number at a low level. The results showed that dithizone-mediated long-term disruption of Paneth cells aggravated intestinal injury, intestinal stem cell (ISC) loss, and microbiota disorder in DON (2 mg/kg)-treated mice. Unexpectedly, the number of goblet cells and proliferative cells was boosted in mice treated with dithizone and DON. After dithizone and DON treatments, the Firmicutes/Bacteroidetes (F/B) ratio was reduced, and the increased abundance of Dubosiella and the decreased abundance of Lactobacillus were observed in mice. The functional recovery of Paneth cells by lysozyme (200 U/day) supplementation improved intestinal injury and ISC loss in mice after DON challenge. In addition, lysozyme also promoted the growth and ISC activity of intestinal organoids. Taken together, these results demonstrate the protective role of Paneth cells in DON-induced intestinal injury. Our study raises a novel target, Paneth cell, for the treatment of DON exposure.

Paneth cells in farm animals: current status and future direction.

A healthy intestine plays an important role in the growth and development of farm animals. In small intestine, Paneth cells are well known for their regulation of intestinal microbiota and intestinal stem cells (ISCs). Although there has been a lot of studies and reviews on human and murine Paneth cells under intestinal homeostasis or disorders, little is known about Paneth cells in farm animals. Most farm animals possess Paneth cells in their small intestine, as identified by various staining methods, and Paneth cells of various livestock species exhibit noticeable differences in cell shape, granule number, and intestinal distribution. Paneth cells in farm animals and their antimicrobial peptides (AMPs) are susceptible to multiple factors such as dietary nutrients and intestinal infection. Thus, the comprehensive understanding of Paneth cells in different livestock species will contribute to the improvement of intestinal health. This review first summarizes the current status of Paneth cells in pig, cattle, sheep, horse, chicken and rabbit, and points out future directions for the investigation of Paneth cells in the reviewed animals.

Multifaceted involvements of Paneth cells in various diseases within intestine and systemically.

Serving as the guardians of small intestine, Paneth cells (PCs) play an important role in intestinal homeostasis maintenance. Although PCs uniquely exist in intestine under homeostasis, the dysfunction of PCs is involved in various diseases not only in intestine but also in extraintestinal organs, suggesting the systemic importance of PCs. The mechanisms under the participation of PCs in these diseases are multiple as well. The involvements of PCs are mostly characterized by limiting intestinal bacterial translocation in necrotizing enterocolitis, liver disease, acute pancreatitis and graft-vs-host disease. Risk genes in PCs render intestine susceptible to Crohn's disease. In intestinal infection, different pathogens induce varied responses in PCs, and toll-like receptor ligands on bacterial surface trigger the degranulation of PCs. The increased level of bile acid dramatically impairs PCs in obesity. PCs can inhibit virus entry and promote intestinal regeneration to alleviate COVID-19. On the contrary, abundant IL-17A in PCs aggravates multi-organ injury in ischemia/reperfusion. The pro-angiogenic effect of PCs aggravates the severity of portal hypertension. Therapeutic strategies targeting PCs mainly include PC protection, PC-derived inflammatory cytokine elimination, and substituting AMP treatment. In this review, we discuss the influence and importance of Paneth cells in both intestinal and extraintestinal diseases as reported so far, as well as the potential therapeutic strategies targeting PCs.

From birth to death: The hardworking life of Paneth cell in the small intestine.

Paneth cells are a group of unique intestinal epithelial cells, and they play an important role in host-microbiota interactions. At the origin of Paneth cell life, several pathways such as Wnt, Notch, and BMP signaling, affect the differentiation of Paneth cells. After lineage commitment, Paneth cells migrate downward and reside in the base of crypts, and they possess abundant granules in their apical cytoplasm. These granules contain some important substances such as antimicrobial peptides and growth factors. Antimicrobial peptides can regulate the composition of microbiota and defend against mucosal penetration by commensal and pathogenic bacteria to protect the intestinal epithelia. The growth factors derived from Paneth cells contribute to the maintenance of the normal functions of intestinal stem cells. The presence of Paneth cells ensures the sterile environment and clearance of apoptotic cells from crypts to maintain the intestinal homeostasis. At the end of their lives, Paneth cells experience different types of programmed cell death such as apoptosis and necroptosis. During intestinal injury, Paneth cells can acquire stem cell features to restore the intestinal epithelial integrity. In view of the crucial roles of Paneth cells in the intestinal homeostasis, research on Paneth cells has rapidly developed in recent years, and the existing reviews on Paneth cells have mainly focused on their functions of antimicrobial peptide secretion and intestinal stem cell support. This review aims to summarize the approaches to studying Paneth cells and introduce the whole life experience of Paneth cells from birth to death.

Functional fiber enhances the effect of every-other-day fasting on insulin sensitivity by regulating the gut microecosystem.

Every-other-day fasting (EODF), which involves alternating days of fasting and feeding, has been reported to lower obesity, and dietary fibers can improve metabolism by altering gut microbiota. This study investigated whether the combination of functional fiber (FF) and EODF (FF-EODF) can further improve insulin sensitivity by regulating the composition of microbiota and curbing weight gain. Twenty-eight diet-induced obese (DIO) mice were randomly divided into four experimental groups (n=7): (1) ad-libitum (AL), (2) EODF, (3) 4% FF-EODF and (4) 6% FF-EODF. After exposure to a high-fat basal diet (HFD) for 12 weeks (1-12 weeks, period 1) and then to a normal chow diet (NCD) for 4 weeks (13-16 weeks, period 2). Compared with EODF alone, 6% FF-EODF treatment could significantly improve the insulin sensitivity of DIO mice without affecting their body weight during period 1(HFD), while significantly increasing satiety, energy consumption, weight, and adipose loss, and insulin sensitivity during period 2 (NCD). Meanwhile, FF-EODF showed a higher increase in short-chain fatty acids (SCFAs) and restored the proportion of induced intraepithelial lymphocytes in the intestinal epithelium compared to EODF alone. Although EODF could increase the relative abundances of Lactobacillus and Bifidobacteriumin, FF supplementation further increased the relative abundance of Lactobacillus, Bifidobacterium, and S24-7 in the intestine. This increase was positively correlated with the decrease in adiposity and insulin resistance, indicating that FF plays a key role in insulin improvement. Our study demonstrated the potential of FF-EODF in promoting insulin sensitivity and reducing body weight via beneficial regulation of gut microecosystem.

Functional Fiber Reduces Mice Obesity by Regulating Intestinal Microbiota.

Obesity may cause metabolic syndrome and has become a global public health problem, and dietary fibers (DF) could alleviate obesity and metabolic syndrome by regulating intestinal microbiota. We developed a functional fiber (FF) with a synthetic mixture of polysaccharides, high viscosity, water-binding capacity, swelling capacity, and fermentability. This study aimed to investigate the effect of FF on obesity and to determine its prevention of obesity by modulating the gut microbiota. Physiological, histological, and biochemical parameters, and gut microbiota composition were investigated in the following six groups: control group (Con), high-fat diet group (HFD), low-fat diet group (LFD, conversion of HFD to LFD), high-fat +8% FF group (8% FF), high-fat +12% FF group (12% FF), and high-fat +12% FF + antibiotic group (12% FF + AB). The results demonstrated that 12% FF could promote a reduction in body weight and epididymal adipocyte area, augment insulin sensitivity, and stimulate heat production from brown adipose tissue (BAT) (p < 0.05). Compared with the HFD, 12% FF could also significantly improve the intestinal morphological integrity, attenuate systemic inflammation, promote intestinal microbiota homeostasis, and stabilize the production of short-chain fatty acids (SCFAs) (p < 0.05). Consistent with the results of 12% FF, the LFD could significantly reduce the body weight and epididymal adipocyte area relative to the HFD (p < 0.05), but the LFD and HFD showed no significant difference (p > 0.05) in the level of inflammation and SCFAs. Meanwhile, 12% FF supplementation showed an increase (p < 0.05) in the abundance of the Bifidobacterium, Lactococcus, and Coprococcus genus in the intestine, which had a negative correlation with obesity and insulin resistance. Additionally, the treatment with antibiotics (12% FF + AB) could inhibit the effect of FF in the HFD. The Kyoto Encyclopedia of Genes and Genomes (KEGG) function prediction revealed that 12% FF could significantly inhibit the cyanogenic amino acid metabolic pathway and decrease the serum succinate concentration relative to the HFD group. The overall results indicate that 12% FF has the potential to reduce obesity through the beneficial regulation of the gut microbiota and metabolites.

Bioactive triple peptide inhibits inflammasome activation to alleviate Salmonella-induced intestinal inflammation in mice via modulation of host defense and bacterial virulence.

Over the past years, Salmonella typhimurium has been considered an important pathogen that causes intestinal diseases and spells enormous economic shock to animal husbandry all over the world. Pyroptosis and inflammasome are involved in intestinal S. typhimurium infections. This study aims to explore the protective effects and potential mechanisms of a bioactive triple peptide (BTP) on S. typhimurium-induced intestinal infection. In this report, BTP exhibited anti-inflammatory and antibacterial activities in vivo (S. typhimurium-infected C57BL/6 mice) and in vitro (S. typhimurium-challenged THP-1 cells). We found that BTP significantly alleviated intestinal injuries and inflammation in S. typhimurium-infected mice. Besides, organ hypertrophy and bacteria translocation were improved effectively after BTP treatment. In macrophages, inflammasome activation caused by S. typhimurium infection was inhibited by BTP treatment. Of note, BTP significantly inhibited the adhesion and invasion of S. typhimurium to THP-1 cells. Moreover, the gene expressions of fljB and fliC were suppressed by BTP. All in all, our results suggest that BTP has the potential for alleviating S. typhimurium-induced inflammation.

Circulating Exosomal miR-221 from Maternal Obesity Inhibits Angiogenesis via Targeting Angptl2.

Maternal obesity disrupts both placental angiogenesis and fetus development. However, the links between adipocytes and endothelial cells in maternal obesity are not fully understood. The aim of this study was to characterize exosome-enriched miRNA from obese sow's adipose tissue and evaluate the effect on angiogenesis of endothelial cells. Plasma exosomes were isolated and analyzed by nanoparticle tracking analysis (NTA), electron morphological analysis, and protein marker expression. The number of exosomes was increased as the gestation of the sows progressed. In addition, we found that exosomes derived from obese sows inhibited endothelial cell migration and angiogenesis. miRNA detection showed that miR-221, one of the miRNAs, was significantly enriched in exosomes from obese sows. Further study demonstrated that exosomal miR-221 inhibited the proliferation and angiogenesis of endothelial cells through repressing the expression of Angptl2 by targeting its 3' untranslated region. In summary, miR-221 was a key component of the adipocyte-secreted exosomal vesicles that mediate angiogenesis. Our study may be a novel mechanism showing the secretion of "harmful" exosomes from obesity adipose tissues causes placental dysplasia during gestation.

Effect of gestation dietary methionine-to-lysine ratio on methionine metabolism and antioxidant ability of high-prolific sows.

The uptake and metabolism of methionine (Met) are critical for epigenetic regulation, redox homeostasis, and embryo development. Our previous study showed that appropriate supplementation of dietary Met promoted the birth weight and placental angiogenesis of high-prolific sows. To further explore the metabolic effect of Met on pregnant sows, we have evaluated the influence of dietary Met level on Met metabolism, and the relationship between metabolites of Met and reproductive performance, antioxidant ability, and placental angiogenesis throughout the gestation of high-prolific sows. Sixty sows (the 3rd parity, Large White) were randomly divided into 5 groups that were fed diets with standardized ileal digestible (SID) methionine-to-lysine (Met:Lys) ratios of 0.27 (control), 0.32, 0.37, 0.42, and 0.47 from the mating day (gestational d 0, G0d) until the farrowing day. HPLC-MS/MS analysis was used to simultaneously evaluate the metabolites related to Met, e.g. S-adenosylmethionine (SAM), S-adenosylhomocysteine (SAH), homocysteine (Hcy), cysteine (Cys), and glutathione (GSH). The concentration of SAM and SAH in plasma had significant fluctuations, especially in late pregnancy. Increasing dietary Met supplementation significantly improved the plasma SAM and methylation potential (SAM-to-SAH ratio) at d 114 of pregnancy (G114d). Moreover, a positive association of the plasma SAM concentration at G114d was observed with the litter weight of born alive (P < 0.05; R 2 = 0.58). Furthermore, Hcy concentration in plasma was at the lowest level for 0.37 ratio group at G114d. However, it significantly increased during late pregnancy. Moreover, there were negative correlations between plasma Hcy concentration at G114d (P < 0.05) and the placental vascular density in the fold and stroma (P < 0.05). Compared with the control group, the expression of vascular endothelial growth factor-A (VEGF-A) in the placenta tissue of 0.37 ratio group increased significantly (P < 0.05). Collectively, these findings indicate that dietary Met:Lys ratio (0.37 to 0.57) in the pregnant diet dose not influence the antioxidant ability of the high-prolific sows; however, the improvement of fetal development and placental angiogenesis of high-prolific sows by supplementation of Met are closely associated to the key Met-related metabolite of SAM and Hcy, respectively.

The Effect of Functional Fiber on Microbiota Composition in Different Intestinal Segments of Obese Mice.

The gastrointestinal tract is a heterogeneous ecosystem with distinct, stratified environments, which leads to different microbial composition in different intestinal segments. The regional heterogeneity of intestinal microbiota complicates the relationship between diet and microbiota. Few studies have focused on the effects of different diets on microbiota in different intestinal segments. This study aimed to investigate the effects of functional fiber on the microbial composition in multiple intestinal segments from a high-fat diet compared with a normal chow diet. We found that the response of microbiota from different intestinal segments to diet was related to the intestinal physiologic function and the physicochemical properties of dietary nutrients. A high-fat diet drove changes in the microbial composition in the hindgut, possibly by affecting the digestive environment of the foregut, and increased the regional heterogeneity of the whole intestinal microbiota. The supplementation of functional fiber promoted the microbial transfer and colonization from the anterior to the posterior intestinal segments, and increased the regional similarity of intestinal microbiota accordingly, particularly within the hindgut. The gut fermentation of the functional fiber, which mainly occurred in the hindgut, resulted in a significant change in the microbial composition and metabolism in the cecum and colon, with richer carbohydrate metabolism-related bacteria, including Mucispirillum, Prevotella, Anaerostipes, Oscillospira, Ruminococcus, Bacteroides, Coprococcus, Ruminococcus (Lachnospiraceae), and Allobaculum, and higher production of acetate and butyrate. We concluded that multiple regulatory mechanisms of diets which affect microbiota composition exist, including microbial metabolism, microbial migration, and the regulation of the intestinal environment.

Effect of Sows Gestational Methionine/Lysine Ratio on Maternal and Placental Hydrogen Sulfide Production.

The placenta is a unique bond between the mother and the fetus during pregnancy, and a proper placental angiogenesis is vital for fetal development. H2S is an endogenous stimulator of angiogenesis that is mainly produced by the methionine transsulfurationpathway. The goal of this study was to evaluate the effect of gestational dietary methionine on maternal and placental H2S production in sows. Multiparous sows (Large×White; third parity; n = 65) were randomly allocated into five groups, with feed diets comprisingstandardized ileal digestible methionine/lysine (Met/Lys) ratios of 0.27 (nutrient requirements of swine (NRC); 2012 level), 0.32, 0.37, 0.42, and 0.47, respectively. The litter size and weight at birth were measured and recorded. Maternal blood samples were obtained at embryonic day (E) E40 d, E90 d, and E114 d of gestation. The placental samples were collected at parturition. The results showed that maternal plasma H2S concentration was not affected at E40 d. However, the maternal plasma H2S concentration changed quadratically with the dietary Met/Lys ratio at E90 d (p < 0.01) and E114 d (p = 0.03). The maximum maternal plasma H2S concentration was at the dietary Met/Lys ratio of 0.37. Meanwhile, maternal plasma H2S concentration was positively correlated with piglets born alive (p < 0.01) and litter weight (p < 0.01). Consistent with the maternal plasma, the placental H2S concentration also changed quadratically with the dietary Met/Lys ratio (p = 0.03); the Met/Lys ratio of 0.37 showed the maximum H2S concentration. In conclusion, our findings revealed that the gestational dietary Met/Lys ratio could affect maternal and placental H2S concentrations, which may be an important molecular mechanism affecting placental angiogenesis and piglet development.

Combined Soluble Fiber-Mediated Intestinal Microbiota Improve Insulin Sensitivity of Obese Mice.

Dietary fiber, an important regulator of intestinal microbiota, is a promising tool for preventing obesity and related metabolic disorders. However, the functional links between dietary fiber, intestinal microbiota, and obesity phenotype are still not fully understood. Combined soluble fiber (CSF) is a synthetic mixture of polysaccharides and displays high viscosity, water-binding capacity, swelling capacity, and fermentability. We found that supplementing high-fat diet (HFD) with 6% CSF significantly improved the insulin sensitivity of obese mice without affecting their body weight. Replacing the HFD with normal chow basal diet (NCD), the presence of CSF in the feed significantly enhanced satiety, decreased energy intake, promoted weight and fat loss, and augmented insulin sensitivity. CSF also improved the intestinal morphological integrity, attenuated systemic inflammation, promoted intestinal microbiota homeostasis, and stabilized the production of short-chain fatty acids (SCFAs) that was perturbed during HFD-induced obesity, and these stabilizing effects were more prominent when the basal diet was switched to NCD. The enrichment of bacteria of the S24-7 family and Allobaculum genus increased markedly in the intestine following 6% CSF supplementation- and correlated with decreased adiposity and insulin resistance. Five bacterial genera that were decreased by CSF, including Oscillospira, unclassified Lachonospitaceae, unclassified Clostridiales, unclassified Desulfovibrionaceae, and unclassified Ruminococcae, were subjected to co-occurrence network analysis and were positively correlated to adiposity and insulin resistance, indicating a key role in the microbial response to CSF. Thus, CSF has a potential to promote insulin sensitivity and even reduce obesity via beneficial regulation of the gut microecosystem.

Early-Life Intervention Using Fecal Microbiota Combined with Probiotics Promotes Gut Microbiota Maturation, Regulates Immune System Development, and Alleviates Weaning Stress in Piglets.

Previous studies have suggested that immune system development and weaning stress are closely related to the maturation of gut microbiota. The early-life period is a "window of opportunity" for microbial colonization, which potentially has a critical impact on the development of the immune system. Fecal microbiota transplantation (FMT) and probiotics are often used to regulate gut microbial colonization. This study aims to test whether early intervention with FMT using fecal microbiota from gestation sows combined with Clostridium butyricum and Saccharomyces boulardii (FMT-CS) administration could promote the maturation of gut microbiota and development of immune system in piglets. Piglets were assigned to control (n = 84) and FMT-CS treatment (n = 106), which were treated with placebo and bacterial suspension during the first three days after birth, respectively. By 16S rRNA gene sequencing, we found that FMT-CS increased the α-diversity and reduced the unweighted UniFrac distances of the OTU community. Besides, FMT-CS increased the relative abundance of beneficial bacteria, while decreasing that of opportunistic pathogens. FMT-CS also enhanced the relative abundance of genes related to cofactors and vitamin, energy, and amino acid metabolisms during the early-life period. ELISA analysis revealed that FMT-CS gave rise to the plasma concentrations of IL-23, IL-17, and IL-22, as well as the plasma levels of anti-M.hyo and anti-PCV2 antibodies. Furthermore, the FMT-CS-treated piglets showed decreases in inflammation levels and oxidative stress injury, and improvement of intestinal barrier function after weaning as well. Taken together, our results suggest that early-life intervention with FMT-CS could promote the development of innate and adaptive immune system and vaccine efficacy, and subsequently alleviate weaning stress through promoting the maturation of gut microbiota in piglets.

FSGHF3 and peptides, prepared from fish skin gelatin, exert a protective effect on DSS-induced colitis via the Nrf2 pathway.

Inflammatory bowel disease (IBD), including Crohn's disease (CD) and ulcerative colitis (UC), is a chronic inflammatory disease affecting the colon, and its incidence is rising worldwide. We previously found that fish skin gelatin hydrolysate fraction 3 (FSGHF3), isolated from fish skin gelatin hydrolysate, could exert antioxidant effects and maintain tight junctions in IPEC-J2 cells. Further HPLC-ESI-QqQ-MS results revealed that this fraction mainly included some peptides. Here, we aim to evaluate the effects of FSGHF3 and peptides in the mice model of dextran sodium sulfate (DSS)-induced colitis and LPS induced inflammation in IECs. The results show that FSGHF3 significantly ameliorates the clinical symptoms of DSS-induced colitis in mice, such as weight loss, disease activity index (DAI), colon shortening, spleen hypertrophy, histological scores, and MPO activity. FSGHF3 and peptide treatment inhibits pro-inflammatory cytokine production, leading to the maintenance of intestinal architecture in vivo and in vitro. Meanwhile, FSGHF3 and peptide treatment promotes antioxidant enzyme expression via activating Nrf2, which results in the removal of ROS and inhibition of NF-κB activation. Overall, our results suggest that FSGHF3 and peptides may be promising potential candidates for the alleviation of colitis.

Maternal Eicosapentaenoic Acid Feeding Decreases Placental Lipid Deposition and Improves the Homeostasis of Oxidative Stress Through a Sirtuin-1 (SIRT1) Independent Manner.

SCOPE: Maternal obesity has been associated with increased placental lipotoxicity and impaired mitochondrial function. Sirtuin-1 (SIRT1) is an important regulator of both lipid metabolism and mitochondrial biogenesis. The present study aims to determine whether supplementation of the maternal diet with eicosapentaenoic acid (EPA) can decrease placental lipid deposition and improve antioxidant ability, in a SIRT1-dependent manner. METHODS AND RESULTS: Pregnant SIRT1+/- mice (mated with male SIRT1+/- ) are fed a high-fat diet consisting of 60% of the kcal from fat, or an equienergy EPA diet for 18.5 d. Supplementation with EPA significantly changes maternal plasma, placental and fetal fatty acid composition, and decreases placental and fetal lipid content. In addition, placental antioxidant capacity and lipid peroxidation products are increased, placental uncoupling protein 1 (UCP1) and PPARγ coactivator-1 α (PGC1α) expression are activated, and mitochondrial swelling decreases. While SIRT1 deficiency has little effect on placental fatty acid composition and lipid content, decreased fetal lipid deposition is observed, placental PGC1α expression decreases, mitochondrial swelling increases, and placental total superoxide dismutase (T-SOD) activity increases. Both EPA and SIRT1 have no effect on BODIPY-FL-C16 uptake. Interestingly, there is no significant interaction between diet and genotype. CONCLUSION: Maternal EPA feeding decreases placental lipid deposition and improves placental oxidative stress homeostasis independent of SIRT1.