Chronic heat stress induces the disorder of gut transport and immune function associated with endoplasmic reticulum stress in growing pigs

Bacillus amyloliquefaciens attenuates the intestinal permeability, oxidative stress and endoplasmic reticulum stress: transcriptome and microbiome analyses in weaned piglets

Endoplasmic reticulum (ER) stress is related to oxidative stress (OS) and leads to intestinal injury. Bacillus amyloliquefaciens SC06 (SC06) can regulate OS, but its roles in intestinal ER stress remains unclear. Using a 2 × 2 factorial design, 32 weaned piglets were treated by two SC06 levels (0 or 1 × 108 CFU/g), either with or without diquat (DQ) injection. We found that SC06 increased growth performance, decreased ileal permeability, OS and ER stress in DQ-treated piglets. Transcriptome showed that differentially expressed genes (DEGs) induced by DQ were enriched in NF-κB signaling pathway. DEGs between DQ- and SC06 + DQ-treated piglets were enriched in glutathione metabolism pathway. Ileal microbiome revealed that the SC06 + DQ treatment decreased Clostridium and increased Actinobacillus. Correlations were found between microbiota and ER stress genes. In conclusion, dietary SC06 supplementation increased the performance, decreased the permeability, OS and ER stress in weaned piglets by regulating ileal genes and microbiota.

Alterations of intestinal mucosal barrier, cecal microbiota diversity, composition, and metabolites of yellow-feathered broilers under chronic corticosterone-induced stress: a possible mechanism underlying the anti-growth performance and glycolipid metabolism disorder

This study aimed to explore alterations in growth performance, glycolipid metabolism disorders, intestinal mucosal barrier, cecal microbiota community, and metabolites in a chronic corticosterone (CORT)-induced stress (CCIS) broiler model. Results showed that compared with control (CON) broilers, in CCIS broilers: (i) the final body weight (BW), BW gain, and average daily gain were significantly reduced. (ii) The glycolipid metabolism disorder and impairement of intestinal immune barrier and physical barrier function were observed. (iii) Diversity and richness of cecal microbiota were obviously increased. From phylum to genus level, the abundances of Firmicutes and Faecalibacterium were significantly decreased, while the abundances of Proteobacteria, RuminococcaceaeUCG-005, and Escherichia coli (Shigella) were significantly increased. Microbial network analysis and function pathways prediction showed that cecal microbiota was mainly concentrated in translation, metabolism, nucleotide metabolism, and endocrine system. (iv) The main differential metabolites identified include steroids and their derivatives, amino acids, fatty acids, and carbohydrates; among which 37 metabolites were significantly upregulated, while 27 metabolites were significantly downregulated. These differential metabolites were mainly enriched in pathways related to steroid hormone biosynthesis and tyrosine metabolism. (v) Correlation between cecal microbiota and glycolipid metabolism indexes showed that BW and total cholesterol (TC) were positively correlated with Christensenellaceae_R.7_group and Escherichia_Shigella, respectively. Furthermore, the downregulated Faecalibacterium and Christensenellaceae were negatively correlated with the upregulated differentially expressed metabolites. These findings suggested that CCIS altered cecal microbiota composition and metabolites, which led to glycolipid metabolism disorder and impaired the nutritional metabolism and immune homeostasis, providing a theoretical basis for efforts to eliminate the harm of chronic stress to human health and animal production.

IMPORTANCE

The study aimed to determine the influence of altered intestinal mucosal barrier, cecum flora community, and metabolites on anti-growth performance, glycolipid metabolism disorders of chronic corticosterone (CORT)-induced stress (CCIS) broilers. Compared with control (CON) broilers, in CCIS broilers: (i) anti-growth performance, glycolipid metabolism disorder, and impaired intestinal immune barrier and physical barrier function were observed. (ii) From phylum to genus level, the abundances of Firmicutes and Faecalibacterium were decreased; whereas, the abundances of Proteobacteria, RuminococcaceaeUCG-005, and Escherichia coli (Shigella) were increased. (iii) Differential metabolites in cecum were mainly enriched in steroid hormone biosynthesis and tyrosine metabolism. (iv) Body weight (BW) and total cholesterol (TC) were positively correlated with Christensenellaceae_R.7_group and Escherichia_Shigella, respectively, while downregulated Faecalibacterium and Christensenellaceae were negatively correlated with upregulated metabolites. Our findings suggest that CCIS induces anti-growth performance and glycolipid metabolism disorder by altering cecum flora and metabolites, providing a theoretical basis for efforts to eliminate the effect of chronic stress on human health and animal production.

Folic Acid and Taurine Alleviate the Impairment of Redox Status, Immunity, Rumen Microbial Composition and Fermentation of Lambs under Heat Stress

The aim of this study was to investigate if the supplementation of folic acid and taurine can relieve the adverse effects of different levels of heat stress (HS) on growth performance, physiological indices, antioxidative capacity, immunity, rumen fermentation and microbiota. A total of 24 Dorper × Hu crossbred lambs (27.51 ± 0.96 kg) were divided into four groups: control group (C, 25 °C), moderate HS group (MHS, 35 °C), severe HS group (SHS, 40 °C), and the treatment group, under severe HS (RHS, 40 °C, 4 and 40 mg/kg BW/d coated folic acid and taurine, respectively). Results showed that, compared with Group C, HS significantly decreased the ADG of lambs (p < 0.05), and the ADG in the RHS group was markedly higher than in the MHS and SHS group (p < 0.05). HS had significant detrimental effects on physiological indices, antioxidative indices and immune status on the 4th day (p < 0.05). The physiological indices, such as RR and ST, increased significantly (p < 0.05) with the HS level and were significantly decreased in the RHS group, compared to the SHS group (p < 0.05). HS induced the significant increase of MDA, TNF-α, and IL-β, and the decrease of T-AOC, SOD, GPx, IL-10, IL-13, IgA, IgG, and IgM (p < 0.05). However, there was a significant improvement in these indices after the supplementation of folic acid and taurine under HS. Moreover, there were a significant increase in Quinella and Succinivibrio, and an evident decrease of the genera Rikenellaceae_RC9_gut_group and Asteroleplasma under HS (p < 0.05). The LEfSe analysis showed that the genera Butyrivibrio, Eubacterium_ventriosum_group, and f_Bifidobacteriaceae were enriched in the MHS, SHS and RHS groups, respectively. Correlated analysis indicated that the genus Rikenellaceae_RC9_gut_group was positively associated with MDA, while it was negatively involved in IL-10, IgA, IgM, and SOD (p < 0.05); The genus Anaeroplasma was positively associated with the propionate and valerate, while the genus Succinivibrio was negatively involved in TNF-α (p < 0.05). In conclusion, folic acid and taurine may alleviate the adverse effects of HS on antioxidant capacity, immunomodulation, and rumen fermentation of lambs by inducing changes in the microbiome that improve animal growth performance.

L-Theanine alleviates heat stress through modulation of gut microbiota and immunity

BACKGROUND

Heat stress (HS) damages the intestines, disrupting gut microbiota and immune balance. l-Theanine (LTA), found in tea, alleviates oxidative stress and cell apoptosis under HS; however, its effects on gut microbiota and immunity under HS remain unclear. To investigate this, we administered LTA doses of 100, 200, and 400 mg·kg-1 ·d-1 to C57BL/6J mice. On day 44, the model group and LTA intervention group were subjected to continuous 7-day HS treatment for 2 h per day.

RESULTS

The results demonstrated that LTA intervention improved food intake, body weight, and intestinal epithelium, and reduced the water intake of heat-stressed mice. It increased the abundance of Turicibacter, Faecalibaculum, Bifidobacterium, and norank_f_Muribaculaceae, while reducing that of Lachnoclostridium and Desulfovibrio. LTA intervention also increased the concentrations of amino acid and lipid metabolites, regulated macrophage differentiation stimulated by gut microbiota and metabolites, reduced the antigen presentation by macrophages to the specific immune system, promoted B-cell differentiation and sIgA secretion, inhibited pro-inflammatory factors, and enhanced intestinal defense. Mechanistically, LTA downregulated heat shock protein 70 expression and the TLR4/NF-κB/p38 MAPK signaling pathway, restoring gut microbiota and immune balance.

CONCLUSION

We suggest that LTA can alleviate HS by modulating gut microbiota, metabolites, and immunity, indicating its potential as a natural active ingredient for anti-HS food products. © 2023 Society of Chemical Industry.

Effects of the compound extracts of Caprifoliaceae and Scutellaria baicalensis Georgi on the intestinal microbiota and antioxidant function

According to the Chinese encyclopedia "Ben Cao Gang Mu" (AD 1552-1578), Caprifoliaceae and Scutellaria baicalensis Georgi are used in traditional Chinese medicine to clear heat, detoxify, and treat wind-heat colds, upper respiratory tract infections, and pneumonia. However, the mechanism and the effects of the compound extracts of Caprifoliaceae and Scutellaria baicalensis Georgi on intestinal health remain unclear. From the perspective of intestinal microbes, this study assessed the antioxidant, anti-inflammatory, and intestinal protective properties of Caprifoliaceae and Scutellaria baicalensis Georgi. Mice received diets with or without Caprifoliaceae and Scutellaria baicalensis Georgi extractive (BCA) for 2 weeks in this study. The results showed that BCA increased body weight gain, feed intake, and catalase (CAT) content in the mice but reduced γ-glutamyl transpeptidase (γ-GT) content in the serum (p < 0.05). BCA improved the Sobs, Chao, and Ace indices, as well as the number of Campylobacterota, Patercibacteria, and Desulfobacterota in the colon microbiota, while it decreased the Firmicutes phylum (p < 0.05). At the genus level, BCA increased Candidatus_Saccharimonas, Helicobacter, unclassified_f_Lachnospiraceae, Alistipes, norank_f_norank_o_Clostridia_vadinBB60_group, norank_f_Ruminococcaceae, unclassified_f_Ruminococcaceae, etc. abundance (p < 0.05), but it significantly decreased Lactobacillus and Lachnospiraceae_UCG_001 abundance (p < 0.05). Moreover, BCA improved the concentration of acetic acid, butyric acid, propionic acid, valeric acid, and isovaleric acid and diminished the concentration of isobutyric acid (p < 0.05). Correlation analysis shows that the changes in short-chain fatty acids and antioxidant and inflammatory indices in the serum were significantly correlated with the BCA-enriched microbiota. This study supplemented a database for the application of Caprifoliaceae and Scutellaria baicalensis Georgi in clinical and animal production.

Chitosan-gentamicin conjugate attenuates heat stress-induced intestinal barrier injury via the TLR4/STAT6/MYLK signaling pathway: In vitro and in vivo studies

Heat stress (HS) has a negative impact on animal health. A modified chitosan-gentamicin conjugate (CS-GT) was prepared to investigate its potential protective effects and mechanism of action on heat stress-induced intestinal mucosa injury in IPEC-J2 cells and mouse 3D intestinal organs in a mouse model. CS-GT significantly (P < 0.01) reversed the decline in transmembrane resistance and increased the FITC-dextran permeability of the IPEC-J2 monolayer fusion epithelium caused by heat stress. Heat stress decreased the expression of the tight binding proteins occludin, claudin1, and claudin2. However, pretreatment with CS-GT significantly increased (P < 0.01) the expression of these tight binding proteins. Mechanistically, CS-GT inhibited the activation of the TLR4/STAT6/MYLK signaling pathway induced by heat stress. Molecular docking showed that CS-GT can bind effectively with TLR4. In conclusion, CS-GT alleviates heat stress-induced intestinal mucosal damage both in vitro and in vivo. This effect is mediated, at least partly, by the inhibition of the TLR4/STAT6/MYLK signaling pathway and upregulation of tight junction proteins. These findings suggest that CS-GT may have therapeutic potential in the prevention and treatment of heat stress-related intestinal injury.

Yeast Peptides Improve the Intestinal Barrier Function and Alleviate Weaning Stress by Changing the Intestinal Microflora Structure of Weaned Lambs

Early weaning stress in lambs leads to decreased feed intake, damage to intestinal morphology, changes in the microbial flora structure, and subsequent complications. Yeast peptides are antimicrobial peptides with anti-inflammatory, antioxidant, and bacteriostasis effects. To study the effects of yeast peptides on relieving weaning stress in lambs, 54 lambs were randomly divided into three groups: ewe-reared (ER), yeast-peptide-treated (AP), and early-weaned (EW) lambs. The body weight and dry matter intake did not significantly differ among all groups. After weaning, the daily gain and feed conversion rate decreased significantly (p < 0.01), but AP showed an upward trend. In the EW group, immunoglobulin (Ig) levels changed significantly post-weaning (IgG decreased; IgA and IgM increased); the villi shortened, the crypt depth increased, and the villi height/crypt depth decreased (p < 0.001). The abundance and diversity of microflora among all groups were not significantly different. A column coordinate analysis showed significant differences in the intestinal microbial structure between the AP and EW groups. Lactobacillus, Aeriscardovia, Ruminosaceae_UCG-014, and Catenisphaera may play key roles in alleviating weaning stress in lambs. Our study provides new clues for alleviating weaning stress in lambs by describing the influence of yeast peptides on the intestinal microflora during weaning.

Multi-omics analysis reveals hepatic lipid metabolism profiles and serum lipid biomarkers upon indoor relevant VOC exposure

As a widespread indoor air pollutant, volatile organic compound (VOC) caused various adverse health effects, especial the damage to liver, which has become a growing public concern. However, the current toxic data are intrinsically restricted in the single or major VOC species. Limited knowledge is available regarding toxic effects, biomarkers and underlying mechanisms of real indoor VOC-caused liver damage. Herein, an indoor relevant VOC exposure model was established to evaluate the hepatic adverse outcomes. Machine learning and multi-omics approaches, including liver lipidomic, serum lipidomic and liver transcriptomic, were utilized to uncover the characteristics of liver damage, serum lipid biomarkers, and involved mechanism stimulated by VOC exposure. The result showed that indoor relevant VOC led to the abnormal hepatic lipid metabolism, mainly manifested as a decrease in triacylglycerol (TG) and its precursor substance diacylglycerol (DG), which could be contributed to the occurrence of hepatic adverse outcomes. In terms of serum lipid biomarkers, five lipid biomarkers in serum were uncovered using machine learning to reflect the hepatic lipid disorders induced by VOC. Multi-omics approaches revealed that the upregulated Dgkq disturbed the interconversion of DG and phosphatidic acid (PA), leading to a TG downregulation. The in-depth analysis revealed that VOC down-regulated FoxO transcription factor, contributing to the upregulation of Dgkq. Hence, this study can provide valuable insights into the understanding of liver damage caused by indoor relevant VOC exposure model VOC exposure, from the perspective of multi-omics analysis.

Chronic Heat Stress Affects Bile Acid Profile and Gut Microbiota in Broilers

Heat stress (HS) can inhibit the growth performance of broilers and cause substantial economic losses. Alterations in bile acid (BA) pools have been reported to be correlated with chronic HS, yet the specific mechanism and whether it is related to gut microbiota remains unclear. In this study, 40 Rugao Yellow chickens were randomly selected and distributed into two groups (20 broilers in each group) when reaching 56-day age: a chronic heat stress group (HS, 36 ± 1 °C for 8 h per day in the first 7 days and 36 ± 1 °C for 24 h in the last 7 days) and a control group (CN, 24 ± 1 °C for 24 h within 14 days). Compared with the CN group, total BAs' serum content decreased, while cholic acid (CA), chenodeoxycholic acid (CDCA), and taurolithocholic acid (TLCA) increased significantly in HS broilers. Moreover, 12α-hydroxylase (CYP8B1) and bile salt export protein (BSEP) were upregulated in the liver, and the expression of fibroblast growth factor 19 (FGF19) decreased in the ileum of HS broilers. There were also significant changes in gut microbial composition, and the enrichment of Peptoniphilus was positively correlated with the increased serum level of TLCA. These results indicate that chronic HS disrupts the homeostasis of BA metabolism in broilers, which is associated with alterations in gut microbiota.

Use of zinc nanoparticles and/or prodigiosin to mitigate heat stress in rabbits

Heat stress (HS) is an environmental challenge affecting animals' health, productivity and welfare. This work aimed to inspect the protective effect of zinc oxide nanoparticles (ZnNPs) and/or prodigiosin (PRG) against inflammation, immune dysfunction, oxidative stress and endoplasmic reticulum (ER) stress triggered by HS in growing rabbits. Growing weaned rabbits (one hundred males, 35 days of age) were randomly assigned into four groups. The first group fed a basal diet without supplementation and the 2nd, 3rd, and 4th groups fed diets containing zinc oxide nanoparticles (ZnNPs, 50mg/kg diet), prodigiosin (PRG, 100 mg/kg diet) or their mixture (ZnPRG) under HS conditions for eight successive weeks. The dietary inclusion with ZnNPs and/or PRG significantly boosted FBW (final body weight), CBWG (cumulative body weight gain), and FCR (feed conversion ratio) and had no substantial impacts on the CFI (cumulative feed intake) as compared with those in HS one. All supplemented treatments significantly unveiled an increase in the values of RBCs, hemoglobin, and platelets and significantly decreased in WBCs, basophils and monocytes with non-statistically effects on hematocrit, MCV, MCHC, neutrophils and eosinophils. Compared with the HS group, all supplemental groups showed a significant reduction in TNFα, IL4, IFN-γ, TLR-4 and amyloid A levels and DNA damage markers (Ohdg) and significantly increased in the levels of NO and lysosome activity. Rabbits in the ZnPRG group had significantly higher Ig G and Ig M levels than in other groups. The highest value of CAT and GSH levels were found in rabbits received the mixture of ZnNPs (50mg) and PRG (100mg) in their diets under elevated temperatures. Additionally, both treatments, PRG and ZnNPS, significantly (P<0.001) reduced the values of MDA and MYO, while all treated groups had significantly reduced PC contents compared with the HS group. Co-supplement with ZnPRG showed a considerable restoration in the higher immune expression of reticulum oxidative such GRP78 and IRE1 in hepatic tissues induced by HS conditions. The mixture of ZnNPs and PRG presented more robust effects in mitigating the adverse impacts of HS in rabbits compared with the individual treatments. Collectively, ZnNPs and/or PRG alleviated oxidative stress and DNA damage. In addition, it enhanced the antioxidant capacity and immune function, and downregulated ER stress such as GRP78 and IRE1 signaling in the hepatic tissues of stressed rabbits.

Effects of chronic heat stress on the immunophenotyping of lymphocytes in immune organs of growing pigs

This study aimed to investigate the effects of chronic heat stress on the immunophenotyping of lymphocytes in immune organs of growing pigs. A single-factor randomized block design was used, and 15 healthy growing large white barrows (5 litters, 3 pigs/litter) with similar body weight (40.8 kg) were assigned into 3 groups (5 pigs in each group). Groups were: control group (Con, in 23 °C environmental control chamber, fed ad libitum), heat stress group (HS, in 33 °C environmental control chamber, fed ad libitum), and pair-fed group (PF, in 23 °C environmental control chamber, fed diets according to the feed intake of HS group). After a 7-d adaption, the experiment lasted for 21 d. The results showed as follows: (1) activated T cells in the thymus of HS pigs were higher than those in PF pigs (P < 0.05). Monocytes and dendritic cells in the thymus of HS pigs were significantly higher than that in Con and PF pigs (P < 0.05), while the proportions of these 2 lymphocytes in the thymus of Con pigs did not differ from PF pigs (P > 0.05). Compared with Con pigs, the proportion of CD4+ (P < 0.05) and CD8+ T cells (P < 0.10) in the thymus was increased in HS pigs, while the proportion of CD4+ and CD8+ T cells in PF pigs did not differ from Con pigs (P > 0.05). (2) Compared with Con pigs, significantly decreased T cells, increased B cells and monocytes were found in the spleen of pigs exposed to heat stress (P < 0.05); the proportions of these 3 types of lymphocytes were not significantly different between Con and PF pigs (P > 0.05). The proportions of CD4+ T cells and Treg cells in the spleen of pigs exposed to heat stress tended to be lower than those in the Con pigs (P < 0.10). (3) The proportion of lymphocytes in the tonsils of pigs exposed to heat stress did not differ from Con pigs (P > 0.05); compared with PF pigs, the proportion of Treg cells was significantly decreased in HS pigs (P < 0.05). In conclusion, chronic heat stress stimulates the development and maturation of T cells in the pig thymus toward CD4+ and CD8+ T cells and increases the proportion of monocytes and dendritic cells; under the condition of chronic heat stress, the immune response process in the spleen of pigs is enhanced, but chronic heat stress impairs the survival of CD4+ T cells in the spleen.