Shiyu Tao

A high-concentrate diet induced colonic epithelial barrier disruption is associated with the activating of cell apoptosis in lactating goats

BackgroundIn ruminants, lower ruminal pH causes massive disruption of ruminal epithelial structure during periods of feeding high-concentrate diets. However, the influence of excessive organic fatty acids in the lumen of hindgut on the epithelial structure is unclear. In this study, twelve mid-lactating goats were randomly assigned to either a HC diet group (65% concentrate of dry matter; n = 6) or a LC diet group (35% concentrate of dry matter; n = 6) for 10 weeks. The colonic epithelial structure was detected by HE staining and transmission electron microscopy (TEM), and the apoptotic status of epithelial cells was estimated by TUNEL method and caspase activities.ResultsHC goats showed higher level of free lipopolysaccharide (LPS) in rumen fluid (p?<?0.01) but not in colonic digesta (p?>?0.05), and higher total volatile fatty acid (VFA) concentrations in rumen fluid (p?<?0.05) and in colonic digesta (p?<?0.01), and higher content of starch in colonic digesta (p?<?0.05) compared to LC goats. HC goats demonstrated profound alterations in the colonic epithelial structure and tight junctions (TJ), apparently due to damage of the epithelium with widened TJs space and nuclear breakdown and mitochondrial swelling. HC goats showed higher level of apoptosis in the colonic epithelium with higher proportion of TUNEL-positive apoptotic cells and increases of caspase-3 and ?3/7 activities, as well as the lower ratio of bcl-2/bax mRNA expression in the colonic mucosa (p?<?0.05). However, ?-defense mRNA was significantly down-regulated in the colonic mucosa of HC goats compared to LC (p?<?0.05). HC goats showed higher level of TJ proteins including claudin-1 and claudin-4 in the colonic mucosa than LC (p?<?0.05). Neither free LPS content in the colonic digesta nor NF-? B protein expression in tissues showed significant difference between HC and LC goats (p?>?0.05).ConclusionsOur results reveal that long-term feeding HC diet to lactating goats causes severe damages to the colonic mucosa barrier associated with activating cells apoptosis.

High Concentrate Diet Induced Mucosal Injuries by Enhancing Epithelial Apoptosis and Inflammatory Response in the Hindgut of Goats

Purpose It is widely accepted that lipopolysaccharide and volatile fatty acids (VFA) accumulate in the digestive tract of ruminants fed diets containing high portions of grain. Compared to the ruminal epithelium, the hindgut epithelium is composed of a monolayer structure that is more “leaky” for lipopolysaccharide and susceptible to organic acid-induced damage. The aim of this study was to investigate changes in epithelial structure, apoptosis and inflammatory response in the hindgut of goats fed a high-concentrate diet for 6 weeks. Experimental Design Eight local Chinese goats with rumen cannulas were randomly assigned to two groups: one group was fed a high-concentrate diet (65% concentrate of dry matter, HC) and the other group was fed a low-concentrate diet (35% concentrate of dry matter, LC) for 6 wks. Ruminal fluid, plasma, and hindgut mucosa tissues were collected. Histological techniques, real-time PCR and western blotting were used to evaluate the tissues structure, cell apoptosis and local inflammation in the hindguts. Results Feeding HC diet for 6 wks resulted in a significant decrease of ruminal pH (p<0.01), and ruminal lipopolysaccharide concentrations were significantly increased in HC goats (p<0.05). Obvious damage was observed to mucosal epithelium of the hindgut and the intercellular tight junctions in HC, but not in LC, goats. The expression of MyD88 and caspase-8 mRNA was increased in colonic epithelium of HC goats compared to LC (p<0.05), and the expression of TLR-4 and caspase-3 showed a tendency to increase. In the cecum, interleukin-1β mRNA expression was decreased (p<0.05), and caspase-3 showed a potential increase (p = 0.07) in HC goats. The level of NF-κB protein was increased in colonic epithelium of HC goats. Caspase-3 activity was elevated in both colon and cecum, whereas caspase-8 activity was statistically increased only in colon. Conclusions Feeding a high-concentrate diet to goats for 6 wks led to hindgut mucosal injuries via activating epithelial cells apoptosis and local inflammatory response.

Feeding a High Concentration Diet Induces Unhealthy Alterations in the Composition and Metabolism of Ruminal Microbiota and Host Response in a Goat Model

There is limited knowledge about the impact of long-term feeding a high-concentrate (HC) diet on rumen microbiota, metabolome, and host cell functions. In this study, a combination of mass spectrometry-based metabolomics techniques, 454 pyrosequencing of 16S rDNA genes, and RT-PCR was applied to evaluate the changes of ruminal microbiota composition, ruminal metabolites, and related genes expression in rumen epithelial cells of lactating goats received either a 35% concentrate diet or a 65% concentrate diet for 4 or 19 weeks, respectively. Results show that feeding a HC diet reduced the microbiota diversity and led to the disorders of metabolism in the rumen. The concentrations of lactate, phosphorus, NH3-N and endotoxin Lipopolysaccharide in ruminal fluids, and plasma histamine, lactate and urine N (UN) were increased significantly in goats fed with a HC diet. A significant increase of genes expression related to volatile fatty acids transport, cell apoptosis, and inflammatory responses were also observed in goats fed with a HC diet. Correlation analysis revealed some potential relationships between bacteria abundance and metabolites concentrations. Our findings indicate that a HC diet can induce ruminal microbiota dysbiosis and metabolic disorders, thus increasing risks to host health and potential harm to the environment.

Paraoxonase 2 modulates a proapoptotic function in LS174T cells in response to quorum sensing molecule N-(3-oxododecanoyl)-L-homoserine lactone

A mucus layer coats the gastrointestinal tract and serves as the first line of intestinal defense against infection. N-acyl-homoserine lactone (AHL) quorum-sensing molecules produced by gram-negative bacteria in the gut can influence the homeostasis of intestinal epithelium. In this study, we investigated the effects of two representative long- and short-chain AHLs, N-3-(oxododecanoyl)-homoserine lactone (C12-HSL) and N-butyryl homoserine lactone (C4-HSL), on cell viability and mucus secretion in LS174T cells. C12-HSL but not C4-HSL significantly decreased cell viability by inducing mitochondrial dysfunction and activating cell apoptosis which led to a decrease in mucin expression. Pretreatment with lipid raft disruptor (Methyl-β-cyclodextrin, MβCD) and oxidative stress inhibitor (N-acetyl-L-cysteine, NAC) slightly rescued the viability of cells damaged by C12-HSL exposure, while the paraoxonase 2 (PON2) inhibitor (Triazolo[4,3-a]quinolone, TQ416) significantly affected recovering cells viability and mucin secretion. When LS174T cells were treated with C12-HSL and TQ416 simultaneously, TQ416 showed the maximal positive effect on cells viability. However, if cells were first treated with C12-HSL for 40 mins, and then TQ46 was added, the TQ416 had no effect on cell viability. These results suggest that the C12-HSL-acid process acts at an early step to activate apoptosis as part of C12-HSL’s effect on intestinal mucus barrier function.

Activation of cellular apoptosis in the caecal epithelium is associated with increased oxidative reactions in lactating goats after feeding a high‐concentrate diet

What is the central question of this study? What are the ultrastructural changes of the caecal mucosa and the status of epithelial cellular apoptosis and oxidative reactions in lactating goats after prolonged feeding with a high‐concentrate diet? What is the main finding and its importance? High‐concentrate diet results in ultrastructural damage to the caprine caecal epithelium. Increased oxidative and decreased antioxidative reactions are involved in the process of activating epithelial apoptosis in the caecal epithelium of goats fed a high‐concentrate diet. Our results provide new insight into the relationship between abnormal fermentation in the hindgut and damage to the intestinal mucosal barrier.

Microbiome-Metabolome Responses to a High-Grain Diet Associated with the Hind-Gut Health of Goats

Studies on the effect of a high-concentrate (HC) diet on the hindgut microbiota and metabolome of ruminants are rarely reported. We used 454 pyrosequencing of 16S rDNA genes and gas chromatography-mass spectrometry to evaluate the effects of long-term feeding (HL) or short-term (HS) feeding of an HC diet on changes in bacterial microbiota and their metabolites in the hindgut, with Guanzhong goat as a ruminant model. Results indicated that an HC diet decreased bacterial diversity and induced metabolic disorder in the hindgut. The levels of lactate, endotoxin (lipopolysaccharide, LPS), and volatile fatty acid concentrations were higher in the intestinal digesta of the HC goats than in those of the LC goats (P < 0.05). The level of beta-alanine decreased, whereas the levels of stigmasterol and quinic acid decreased in the cecal and colonic digesta of the HC goats. At the genus level, the abundance of Clostridium and Turicibacter was significantly increased in both the colonic and cecal digesta of the HC goats. Several potential relationships between metabolites and several microbial species were revealed in this study. The mRNA expression of the genes functionally associated with nutrients transport, including NHE2, NHE3, MCT1, and MCT4 were significantly downregulated in the colonic mucosa by the HC diet (P < 0.05). The expression levels of the genes related to the inflammatory response, including TLR4, MYD88, TNF-α, and IL-1β were markedly upregulated in the cecal mucosa by the HC diet (P < 0.05). Our results indicate that an HC diet induces microbiota dysbiosis, metabolic disorders, and mucosal damage in the hindgut of goats.

Comparative proteomic analysis of the effects of high-concentrate diet on the hepatic metabolism and inflammatory response in lactating dairy goats.

BackgroundTo understand the impact of feeding a high-concentrate diet to mid-lactating goats for a long time on liver metabolism and inflammatory response, two dimensional polyacrylamide gel electrophoresis (2-DE) and real-time PCR method were employed to detect proteins differentially expressed in liver and their mRNAs expression in goats fed high concentrate diet (HC) or low concentrate diet (LC). Twelve lactating dairy goats were randomly assigned to either a HC diet group (65 % concentrate of dry matter; n = 6) or a LC diet group (35 % concentrate of dry matter; n = 6) for 10 wk.ResultsTwenty differentially expressed spots (≥2.0-fold changes) in the hepatic tissues were excised and successfully identified using MALDI TOF/TOF. Of these, 8 proteins were up-regulated, while the rest 12 proteins were down-regulated in HC goats compared to LC. Differential expressed proteins including alpha enolase 1 (ENO1), glutamate dehydrogenase 1 (GLUD1), glutathione S-transferase A1 (GSTA1), ATP synthase subunit 5β (ATP5β), superoxide dismutase [Cu-Zn] (SOD1), cytochrom c oxidase subunit Via (COX6A1) and heat shock protein 60 (HSP60) were further verified by real-time PCR and/or western blot at mRNA or protein expression level. Consistent with the 2-DE results, a significant decrease of β-actin protein expression and SOD enzyme activity was observed in liver of HC goats (P < 0.05), while ENO1 protein expression was significantly up-regulated in HC compared to LC goats (P < 0.05) . However, western blot analysis did not show a significant difference of hepatic HSP60 protein between HC and LC group, which did not match the decrease of HSP60 content detected by 2-DE analysis. Real-time PCR showed that glutathione S-transferase P1 (GSTP1) and SOD1 mRNA expression was significantly decreased in liver of HC goats, while cytochrom c oxidase (COX3) and ATPase 8 (ATP8) mRNAs expression were markedly increased compared to LC (P < 0.05). Gene Ontology (GO) analysis revealed that HC diet resulted in altered expression of proteins related to catalytic and mitochondrial metabolism in the liver, and may increase the stress response with up-regulating the expression of differentiation 14 (CD14) cluster and serum amyloid A (SAA) as well as C-reactive protein (CRP) in the liver.ConclusionsThese results suggest that feeding high concentrate diet to lactating goats for 10 wk leads to the activation of the inflammatory response, and decreases the anti-oxidant capacity, and subsequently impairs the mitochondrial function in the liver.

Chronic dexamethasone exposure markedly decreased the hepatic triglyceride accumulation in growing goats

Chronic stress seriously threatens welfare and health in animals and humans. Consecutive dexamethasone (Dex) injection was used to mimic chronic stress previously. In order to investigate the effect of chronic stress on hepatic lipids metabolism, in this study, 10 healthy male goats were randomly allocated into two groups, one received a consecutive injection of Dex via intramuscularly for 3 weeks (Dex group), the other received the same volume of saline as the control group (Con group). Hepatic health and triglyceride (TG) metabolism were analyzed and compared between two groups. The data showed that a significant decrease of TG in plasma and the liver was significantly decreased by Dex (P < .05), while the hepatic nonesterified fatty acid (NEFA) concentration was increased compared to the Con group (P < .05). Consistent with the decrease of TG level, the activity of hepatic lipoprotein lipase (LPL) and hepatic lipase (HL) enzymes activities were significantly enhanced by Dex. Real-time PCR results showed that the mRNA expression of sterol regulatory element binding transcription factor 1 (SREBP-1), acyl-CoA dehydrogenase long chain (ACADL) and acyl-CoA synthetase bubblegum family member 1 (ACSBG1) genes in liver was significantly up-regulated by chronic Dex injection (P < .05), whereas perilipin 2 (PLIN2) and adipose triglyceride lipase (ATGL) mRNA expression was significantly decreased by Dex (P < .05). In addition, no obvious damages were observed in the liver in both Con and Dex groups demonstrating by the sirius red staining, HE staining as well as several biochemical parameters related to the functional status of hepatocytes. Our data indicate that chronic Dex exposure decreases TG levels in the circulation and the liver through activating lipolysis and inhibiting lipogenesis without causing hepatic damages in the growing goats.

Changes in milk performance and hepatic metabolism in mid-lactating dairy goats after being fed a high concentrate diet for 10 weeks

Feeding a high concentrate (HC) diet is a widely used strategy for supporting high milk yields, yet it may cause certain metabolic disorders. This study aimed to investigate the changes in milk production and hepatic metabolism in goats fed different proportions of concentrate in the diet for 10 weeks. In total, 12 mid-lactating goats were randomly assigned to an HC diet (65% concentrate of dry matter, n=6) or a low concentrate (LC) diet (35% concentrate of dry matter, n=6). Compared with LC, HC goats produced greater amounts of volatile fatty acids and produced more milk and milk lactose, fat and protein (P<0.01). HC goats showed a greater concentration of ATP, NAD, plasma non-esterified fatty acids and hepatic triglycerides than LC goats (P<0.05). Real-time PCR results showed that messenger RNA (mRNA) expression of gluconeogenic genes, namely, glucose-6-phosphatase, pyruvate carboxylase and phosphoenolpyruvate carboxykinase were significantly up-regulated and accompanied greater gluconeogenic enzyme activities in the liver of HC goats. Moreover, the expression of hepatic lipogenic genes including sterol regulatory element-binding protein 1c, fatty acid synthase and diacylglycerol acyltransferase mRNA was also up-regulated by the HC diet (P<0.05). HC goats had greater hepatic phosphorylation of AMP-activated protein kinase than LC (P<0.05). Furthermore, histone-3-lysine-27-acetylation contributed to this elevation of gluconeogenic gene expression. These results indicate that lactating goats fed an HC diet for 10 weeks produced more milk, which was associated with up-regulated gene expression and enzyme activities involved in hepatic gluconeogenesis and lipogenesis.

Downregulation of prostaglandin E2 is involved in hindgut mucosal damage in lactating goats fed a high‐concentrate diet

What is the central question of this study? A high‐concentrate (HC) diet results in damage to the hindgut mucosa. The aim of the study was to investigate the status of epithelial proliferation in the hindgut mucosa of goats with subacute ruminal acidosis and, simultaneously, to evaluate prostaglandin E2 synthesis and the downstream signalling pathways. What is the main finding and its importance? The downregulation of local prostaglandin E2 synthesis and its downstream signalling pathway are involved in the process of inhibiting epithelial proliferation in the hindgut epithelium of HC‐fed goats. Our results provide new insight into the relationship between abnormal fermentation in the hindgut and damage to the intestinal mucosal barrier.