Effects of tea polyphenols on intestinal barrier, antioxidant capacity, and cecal microbiota in lion-head geese.

Butyric acid (BA) can potentially enhance the function of the intestinal barrier. However, the mechanisms by which BA protects the intestinal mucosal barrier remain to be elucidated. Given that the Ras homolog gene family, member A (RhoA)/Rho-associated kinase 2 (ROCK2)/Myosin light chain kinase (MLCK) signaling pathway is crucial for maintaining the permeability of the intestinal epithelium, we further investigated whether BA exerts a protective effect on epithelial barrier function by inhibiting this pathway in LPS-induced Caco2 cells. First, we aimed to identify the optimal treatment time and concentration for BA and Lipopolysaccharide (LPS) through a CCK-8 assay. We subsequently measured Trans-epithelial electrical resistance (TEER), FITC-Dextran 4 kDa (FD-4) flux, and the mRNA expression of ZO-1, Occludin, RhoA, ROCK2, and MLCK, along their protein expression levels, and average fluorescence intensity following immunofluorescence staining. We then applied the ROCK2 inhibitor Y-27632 and reevaluated the TEER, FD-4 flux, and mRNA, and protein expression of ZO-1, Occludin, RhoA, ROCK2, and MLCK, as well as their distribution in Caco2 cells. The optimal treatment conditions were determined to be 0.2 mmol/L BA and 5 μg/mL LPS for 24 hours. Compared with LPS treatment alone, BA significantly mitigated the reduction in the TEER, decreased FD-4 flux permeability, increased the mRNA expression of ZO-1 and Occludin, and normalized the distribution of ZO-1 and Occludin in Caco2 cells. Furthermore, BA inhibited the expression of RhoA, ROCK2, and MLCK, and normalized their localization within Caco2 cells. Following treatment with Y-27632, the epithelial barrier function, along with the mRNA and protein expression and distribution of ZO-1 and Occludin were further normalized upon inhibition of the pathway. These findings contribute to a deeper understanding of the potential mechanisms through which BA attenuates LPS-induced impairment of the intestinal epithelial barrier.

To investigate the effect of herb-partitioned moxibustion combined with acupuncture on the expression of intestinal epithelial tight junction (TJ) proteins. Sixty patients diagnosed with mild to moderate Crohn's disease (CD) were allocated into the herb-partitioned moxibustion combined with acupuncture (HMA) group (n = 30) or the mesalazine (MESA) group (n = 30) using a parallel control method. There were 2 sets of acupoints used alternately for HMA treatment. The following points were included in Set A: ST25 (Tianshu), RN6 (Qihai), and RN9 (Shuifen) for herb-partitioned moxibustion and ST36 (Zusanli), ST37 (Shangjuxu), LI11 (Quchi), and LI4 (Hegu) for acupuncture. The points for Set B included BL23 (Shenshu) and BL25 (Dachangshu) for herb-partitioned moxibustion and EX-B2 of T6-T1 (Jiajixue) for acupuncture. The patients received the same treatment 6 times a week for 12 consecutive weeks. The MESA group received 1 g of mesalazine enteric coated tablets 4 times daily for 12 consecutive weeks. Intestinal tissues were stained and examined to compare the morphological and ultrastructural changes before and after the treatment session. Immunohistochemistry and in situ hybridization assays were used to detect the expression of intestinal epithelial TJ proteins zonula occludens-1 (ZO-1), occludin, and claudin-1. The mRNA levels were also evaluated. After the treatment, both herb-partitioned moxibustion combined with acupuncture and mesalazine improved intestinal morphology and ultrastructure of CD patients; the patients treated with HMA showed better improvement. HMA significantly increased the expression of ZO-1 (P = 0.000), occludin (P = 0.021), and claudin-1 (P = 0.016). MESA significantly increased the expression of ZO-1 (P = 0.016) and occludin (P = 0.026). However, there was no significant increase in the expression of claudin-1 (P = 0.935). There was no statistically significant difference between the two groups for the expression of occludin and claudin-1 (P > 0.05). The HMA group showed a significant improvement in ZO-1 expression compared to the MESA group (2333.34 ± 352.51 vs 2160.38 ± 307.08, P = 0.047). HMA significantly increased the expression of ZO-1 mRNA (P = 0.000), occludin mRNA (P = 0.017), and claudin-1 mRNA (P = 0.017). MESA significantly increased the expression of ZO-1 mRNA (P = 0.000), occludin mRNA (P = 0.042), and claudin-1 mRNA (P = 0.041). There was no statistically significant difference between the two groups in the expression of occludin and claudin-1 mRNA (P > 0.05). However, the HMA group showed a significant improvement in ZO-1 mRNA expression compared with the MESA group (2378.17 ± 308.77 vs 2200.56 ± 281.88, P = 0.023). HMA can repair intestinal epithelial barrier lesions and relieve inflammation by upregulating the expression of TJ proteins and their mRNAs.

To study the protective impact of tea polyphenols (TP) on the injury of fibrinolytic functions induced by high-methionine dietary in rats. 50 male Wistar rats were divided by stratified based on body weight into 5 groups with 10 in each group: namely control group, model group, low-dose TP group, medium-dose TP group and high-dose TP group. The rats in model group and TP groups were fed with 3% methionine dietary, control group rats with routine diet. In addition, rats in low-dose, medium-dose and high-dose TP groups were treated with TP at 50, 100 and 200 mg/kg dosage respectively by gavages every day, control group and model group rats were given with same amount distilled water. The animals were sacrificed after 8 weeks. The levels of tissue-type plasminogen activator (t-PA) and type-1 plasminogen activator inhibitor (PAI-1) in plasma were determined by ELISA assays, mRNA levels of t-PA and PAI-1 in aortic arch were detected by RT-PCR, t-PA and PAI-1 expression in aortic arch were detected by immunohistochemistry strept-avidin-biotin complex (SABC). After experiment, the t-PA expression of aortic arch in control group, model group, low-dose TP group, medium-dose TP group and high-dose TP group were 133.03 ± 10.14, 95.46 ± 11.08, 111.97 ± 11.91, 130.23 ± 10.80, 139.39 ± 9.41 (F = 14.15, P < 0.01), respectively, and the PAI-1 expression were 90.91 ± 8.67, 166.76 ± 12.18, 139.63 ± 12.71, 134.66 ± 13.19, 109.49 ± 10.82 (F = 31.44, P < 0.01). The t-PA concentration of plasma were (10.69 ± 1.26), (6.13 ± 0.92), (8.56 ± 1.19), (9.69 ± 0.92), (11.97 ± 1.08) ng/ml, respectively (F = 41.98, P < 0.01), and the PAI-1 concentration of plasma were (6.31 ± 0.81), (16.98 ± 1.27), (11.39 ± 0.82), (8.46 ± 0.67), (8.08 ± 0.91) ng/ml, respectively (F = 207.74, P < 0.01). The mRNA levels of t-PA in aortic arch were 1.12 ± 0.02, 0.75 ± 0.14, 1.01 ± 0.09, 0.95 ± 0.08, 1.05 ± 0.13 (F = 5.77, P < 0.05), and the mRNA levels of PAI-1 in aortic arch were 1.25 ± 0.11, 1.74 ± 0.06, 1.23 ± 0.05, 1.09 ± 0.14, 1.23 ± 0.04 (F = 23.56, P < 0.01). The results indicate that TP seems to have regulatory function on transcription and protein levels of t-PA and PAI-1, in addition to maintaining the balance between PAI-1 and t-PA and healing the injury of fibrinolytic functions in rats induced by high-methionine dietary.

Objective To explore the effect of tea polyphenols on the growth of human papillomavirus 16 (HPV16) subgenes-immortalized human cervical epithelial cells (H8 cells) . Methods Cultured H8 cells were divided into 5 groups to be treated with 0 (control group) , 6.25, 12.5, 25 and 50 mg/L tea polyphenols respectively for 24, 36, and 48 hours, and then cell counting kit-8 (CCK8) assay was performed to detect cell proliferation. After 24 hours of incubation, flow cytometry was conducted to detect cell apoptosis and cell cycle, and fluorescence microscopy to observe the morphology of apoptotic cells. Results After incubation with tea polyphenols at different concentrations for 24, 36 and 48 hours, the proliferation of H8 cells was inhibited, and 12.5 mg/L tea polyphenols could inhibit the relative growth rate of H8 cells in a time-dependent manner. Flow cytometry showed that there was a significant difference in cell apoptosis rate among the 6.25-, 12.5-, 25-, 50-mg/L tea polyphenols groups and the control group (52.62% ± 0.62%, 52.22% ± 0.72%, 42.52% ± 0.90%, 45.96% ± 2.11%, 29.96% ± 0.70% respectively, F = 272.0, P < 0.05) . Moreover, all the tea polyphenol groups showed significantly increased cell apoptosis rate compared with the control group (all P < 0.05) . Fluorescence microscopy showed karyopyknosis, nuclear fragmentation and other typical apoptotic morphological changes in H8 cells in tea polyphenols groups. There were significant differences in the percentage of cells in G1, G2 phase and cell proliferation index among the 5 groups (all P < 0.05) . Compared with the control group, the 6.25-, 12.5-, 25-mg/L tea polyphenols groups showed significantly increased percentage of cells in G1 phase (55.96% ± 0.72%, 54.12% ± 3.20%, 65.30% ± 1.51% respectively, all P < 0.05) , but significantly decreased percentage of cells in G2 phase (3.17 ± 1.82%, 4.94 ± 1.46%, 4.65 ± 4.26% respectively, all P < 0.05) and lower cell proliferation index (0.44 ± 0.01, 0.46 ± 0.02, 0.36 ± 0.01 respectively, all P < 0.05) . Conclusion Tea polyphenols can inhibit the proliferation of H8 cells, induce cell apoptosis, and block cell cycle progression. Key words: Catechin; Cell line, transformed; Cell proliferation; Apoptosis; Cell cycle; Precancerous conditions; Tea polyphenols; Immortalized human cervical epithelial cells

Objective: To study the effect of trefoil factor family (TFF) 3 on the expression of tight junctions (TJs) in the nasal mucosa epithelium of eosinophilic chronic rhinosinusitis (eCRS) and its mechanism. Methods: From September to December 2020, eligible patients from the Department of Otorhinolaryngology of the First Affiliated Hospital of Nanchang University were recruited, including 11 control patients and 37 patients with chronic rhinosinusitis with nasal polyps (CRSwNP), from whom nasal mucosa and nasal polyp tissue samples were collected. Immunohistochemistry (IHC) was used to detect the localization and expression intensity of TFFs (TFF1, TFF2 and TFF3) and TJs (occudin, claudin-1 and ZO-1) in nasal mucosa. Real-time fluorescence quantitative polymerase chain reaction (RT-qPCR) and western blot (WB) were used to detect the mRNA and protein expression. A cell model of tight junction injury in human nasal epithelial cells (HNECs) through stimulation with interleukin (IL)-13 was also established. The optimal modeling concentration and time for HNECs were determined, which were subsequently treated with TFF3 and/or a phosphoinositide 3-kinase (PI3K)-specific inhibitor (LY294002). Finally, RT-qPCR and WB were used to assess the effects of TFF3 on tight junctions and the PI3K/serine/threonine kinase (Akt) signaling pathway. Data were analyzed statistically using GraphPad Prism 7 software. Results: IHC results showed that the expression of TFF1 and TFF3 in nasal mucosa of eCRS group was significantly higher than that of control group (t=4.62, P=0.002; t=5.89, P<0.001), respectively, mainly expressed in goblet cell. The expression of occludin, claudin-1 and ZO-1 in the nasal mucosa of the eCRS group was lower than that of the control group (occludin t=3.98, P=0.019; claudin-1 t=5.15, P=0.002; ZO-1 t=5.42, P=0.001), respectively. WB results showed that the expression of TFF3 in non-eosinophilic chronic sinusitis (Non-eCRS) group and eCRS group was higher than that in the control group (t=3.62, P=0.036; t=5.93, P<0.001). The expression of occludin, claudin-1 and ZO-1 in eCRS group was lower than that in the control group (occludin t=5.14, P=0.002; claudin-1 t=6.35, P<0.001; ZO-1 t=6.64, P<0.001), respectively. The RT-qPCR results showed that compared with the control group, the levels of TFF1 and TFF3 mRNA were increased in the nasal mucosal epithelium of the Non-eCRS and eCRS groups (TFF1 t=3.98, P=0.046, t=4.89, P=0.002; TFF3 t=3.50, P=0.044, t=6.78, P<0.001). There was no statistically significant difference in TFF2 mRNA levels between the Non-eCRS and eCRS groups (t=1.34, P=0.061; t=3.37, P=0.055). Compared with the control group, Non-eCRS and eCRS groups showed a decrease in the mRNA levels of occludin, claudin-1 and ZO-1 (occludin t=4.27, P=0.011, t=5.61, P=0.007; claudin-1 t=3.62, P=0.036, t=6.80, P<0.001; ZO-1 t=3.47, P=0.047, t=7.86, P<0.001). The mRNA levels of TFF3 and TJs in eCRS nasal mucosa tissue showed a moderate positive correlation (occludin r=0.661, claudin-1 r=0.614, ZO-1 r=0.548, all P<0.001); TFF1 showed a low degree of positive correlation with the expression of occludin, claudin-1 and ZO-1 (occludin r=0.467, P=0.040; claudin-1 r=0.362, P=0.012; ZO-1 r=0.425, P=0.025). The establishment of cell models showed that compared with normal HNECs, the mRNA expression of TFF3 was most significantly increased at a concentration of 50 ng/ml stimulated by IL-13 (t=3.72, P=0.013); The mRNA expression of occludin, claudin-1 and ZO-1 decreased (occludin t=3.18, P=0.031; claudin-1 t=3.86, P=0.010; ZO-1 t=5.16, P=0.002). The expression of TFF3 mRNA increased most significantly after 15 hours of IL-13 stimulation (t=3.14, P=0.034); The mRNA expression of occludin, claudin-1 and ZO-1 decreased (occludin t=3.97, P=0.010; claudin-1 t=4.78, P=0.004; ZO-1 t=5.16, P=0.004). TJs damage model could be established by treating HNECs with 50 ng/ml IL-13 for 15 hours. Intervention experiments showed that compared with the IL-13 group, the IL-13+TFF3 group showed an increase in TJs mRNA expression (occludin t=6.10, P=0.009; claudin-1 t=5.90, P=0.013; ZO-1 t=9.44, P=0.007). Compared with the IL-13 group, the expression of TJs protein in the IL-13+TFF3 group increased (occludin t=3.23, P=0.013; claudin-1 t=9.40, P=0.017; ZO-1 t=2.23, P=0.032); The expression of TJs protein decreased in the IL-13+TFF3+LY294002 group (occludin t=4.73, claudin-1 t=8.77, ZO-1 t=3.51, all P<0.001). Compared with the IL-13+TFF3 group, the IL-3+TFF3+LY294002 group showed a decrease in PI3K and p-Akt/Akt protein expression (PI3K t=13.29, p-Akt/Akt t=10.30, all P<0.001). The increased mRNA and protein expression of occludin, claudin-1 and ZO-1 induced by TFF3 were also inhibited by LY294002. Conclusion: TFF3 can up-regulate the expression of occludin, claudin-1, and ZO-1 through PI3K/Akt pathway, and has a certain protective effect on the nasal mucosal epithelial barrier, providing a new idea for treating eCRS.

Rhizoma curcumae Longae ameliorates high dietary carbohydrate-induced hepatic oxidative stress, inflammation in golden pompano Trachinotus ovatus

The objective of this study was to investigate the effects of Lactobacillus reuteri LR1 (LR1), a new strain isolated from the feces of weaning piglets, on the growth performance, intestinal morphology, immune response and intestinal barrier function in weaned piglets. A total of 144 weaned piglets (Duroc×Landrace×Yorkshire, 21 d of age) with an initial BW of 6.49 ± 0.02 kg were randomly assigned to 3 dietary treatments to give 8 pens per treatment and 6 piglets per pen. Piglets were fed with a basal diet (control group), a basal diet supplemented with 75 mg/kg aureomycin +100 mg/kg olaquindox (antibiotic group) or a basal diet supplemented with 5×1010 CFU/kg LR1 (LR1 group) for a 14-d period. At the end of study, the ADG, ADFI and G:F were calculated, and 8 randomly selected piglets from each treatment were euthanized for collecting samples. We found that LR1 treatment increased ADG (22.73%, P < 0.05) compared with the control group. However, no significant differences were observed in ADFI, ADG and G:F between the LR1 group and the antibiotic group. LR1 treatment decreased (P < 0.05) serum IL-6 concentration but increased (P < 0.05) IL-22 and TGF-β content in the mucosa of the ileum compared with the control and antibiotic treatment. We found LR1 treatment increased (P < 0.05) villus height of the ileum and reduced (P < 0.05) crypt depth of the jejunum, and increased (P < 0.05) the ratio of villus height/crypt depth in the jejunum and the ileum compared with the control and antibiotic treatment. Compared with control, LR1 increased (P < 0.05) the mRNA expression of the antimicrobial peptide pBD2 and PG1-5 in the mucosa of the ileum, whereas antibiotic treatment decreased (P < 0.05) expression. Additionally, we demonstrated that LR1 treatment increased (P < 0.05) toll-like receptor (TLR)-2 expression but decreased (P < 0.05) the TLR-4 expression in the mucosa of the ileum compared with the control group. Furthermore, compared with the control and antibiotic treatment, LR1 treatment increased (P < 0.05) the mRNA expression of tight junction protein ZO-1 and claudin-1 in the mucosa of jejunum, and also increased (P < 0.05) the mRNA expression of ZO-1 and occludin in the mucosa of ileum. In conclusion, these data suggest that dietary LR1 supplementation at 5×1010 CFU/kg could improve the growth performance, intestinal morphology and intestinal barrier function in weaned piglets.

In recent years, numerous studies have demonstrated that tea polyphenols (TPPs) can exert neuroprotective effects through the regulation of the PI3K/Akt pathway. The objective of this work was to verify whether TPPs could protect against early brain injury in rats after subarachnoid hemorrhage (SAH) by modulating the PI3K/Akt pathway. A total of 150 rats were randomly rolled into control (C), TPP, and SAH groups. The TPP and SAH groups underwent endovascular perforation to induce SAH, while C group received only endovascular needle puncture and saline injection. Brain water content, Evans Blue (EB) extravasation assay, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining, Western blot, and RT-PCR analyses were performed. Relative to SAH group, TPP treatment considerably improved neurological function scores following SAH, reduced brain edema, cortical neuronal apoptosis, and blood-brain barrier damage. Levels of aquaporin-4 (AQP4) and apoptosis-related protein Bax were considerably lower in the TPP group than in SAH group. Conversely, levels of anti-apoptotic protein Bcl-2 and tight junction protein Zona occludens 1 (ZO-1) were considerably higher in the TPP group. Furthermore, TPP treatment was found to activate the PI3K/Akt signaling. TPPs can mitigate early brain injury caused by SAH in rats by reducing AQP4 levels, alleviating cortical damage, and attenuating neuronal apoptosis. These findings elucidate the protective mechanisms of TPPs against early brain injury following SAH through the regulation of the PI3K/Akt signaling.

IntroductionThe purpose of this study was to explore the effects of tea polyphenols on growth performance, cytokine content, intestinal antioxidant status and intestinal barrier function of lambs, in order to provide reference for intestinal health of ruminants.MethodsThirty weaned lambs (average initial weight 9.32 ± 1.72 kg) were randomly divided into five groups with six lambs in each group. The control group did not add anything but the basic diet mainly composed of Pennisetum and Corn, and the other four groups added 2, 4, 6 g/kg tea polyphenols and 50 mg/kg chlortetracycline to the basic diet, respectively. The experiment lasted for 42 days.ResultsDietary tea polyphenols improved the growth and stress response and reduced intestinal permeability of lambs (p > 0.05), while CTC did not affect the final lamb weight (p > 0.05). Both tea phenols and CTC significantly reduced inflammatory factors and enhanced the immune system (p > 0.05). Dietary tea polyphenols increased villus height, villus height/crypt depth, secretory immunoglobulin A (p > 0.05), and antioxidant enzymes, while decreasing MDA and apoptosis in the intestine (p > 0.05). However, compared with other groups, the content of T-AOC in jejunum did not change significantly (p > 0.05). Tea polyphenols also increased claudin-1 levels in the duodenum, jejunum, and ileum more than CTC (p > 0.05). CTC had a limited effect on the mRNA expression of Occludin and ZO-1, while tea polyphenols increased these in both the duodenum and ileum (p > 0.05).ConclusionThis study demonstrated that tea polyphenols can effectively improve the intestinal barrier of weaned lambs, and that they have anti-inflammatory and antioxidant effects similar to those of antibiotics. Thus, tea polyphenols could be used to replace antibiotics in ensuring safety of livestock products and in achieving the sustainable development of modern animal husbandry.

This study was to illustrate the effects of fructooligosaccharide (FOS) on the antioxidant capacity, intestinal barrier function, and microbial community of weanling pigs. Results showed that FOS reduced the incidence of diarrhea (6.5 vs. 10.8%) of pigs (p < 0.05) but did not affect growth performance when compared with the control group. A diet supplemented with FOS increased ileal mRNA expression of occludin (1.7 vs. 1.0), claudin-1 (1.9 vs. 1.0), claudin-2 (1.8 vs. 1.0), and claudin-4 (1.7 vs. 1.0), as well as colonic mRNA expression of ZO-1 (1.6 vs. 1.0), claudin-1 (1.7 vs. 1.0), occludin (1.9 vs. 1.0), and pBD-1 (1.5 vs. 1.0) when compared with the control group (p < 0.05). FOS supplementation improved the anti-oxidase activity and expression of nuclear factor erythroid-2 related factor 2 (Nrf2), and decreased concentrations of D-lactate (3.05 U/L vs. 2.83 U/L) and TNF-α (59.1 pg/mL vs. 48.0 pg/mL) in the serum when compared with the control group (p < 0.05). In addition, FOS increased Sharpea, Megasphaera, and Bacillus populations in the gut when compared with the control group (p < 0.05). Association analysis indicated that mRNA expression of occludin and claudin-1 in the ileal mucosa were correlated positively with populations of Sharpea and Bacillus (p < 0.05). Furthermore, mRNA expression of occludin and claudin-1 in the colonic mucosa were correlated positively with abundances of Sharpea, Lactobocillus, and Bifidobacterium (p < 0.05). In conclusion, FOS activated Nrf2 signaling and increased the expression of specific tight junction proteins, which were associated with reduced diarrhea incidence.

BackgroundIntestinal barrier dysfunction is not only the consequence of liver cirrhosis, but also an active participant in the development of liver cirrhosis. Previous studies showed that external administration of insulin-like growth factor 1 (IGF-1) improved intestinal barrier function in liver cirrhosis. However, the mechanism of IGF-1 on intestinal barrier in liver cirrhosis is not fully elucidated. The present study aims to investigate the mechanisms of IGF-1 improving intestinal barrier function via regulating tight junctions in intestines.MethodsWe used carbon tetrachloride induced liver cirrhotic rats to investigate the effect of IGF-1 on intestinal claudin-1 and occludin expressions, serum alanine transaminase (ALT) and aspartate transaminase (AST) levels, severity of liver fibrosis, portal pressures, enterocytic apoptosis and lipopolysaccharides (LPS) levels in portal vein. The changes of IGF-1 in serum during the development of rat liver cirrhosis were also evaluated. Additionally, we assessed the effect of IGF-1 on claudin-1 and occludin expressions, changes of transepithelial electrical resistance (TEER) and apoptosis in Caco-2 cells to confirm in vivo findings.ResultsSerum IGF-1 levels were decreased in the development of rat liver cirrhosis, and external administration of IGF-1 restored serum IGF-1 levels. External administration of IGF-1 reduced serum ALT and AST levels, severity of liver fibrosis, LPS levels in portal vein, enterocytic apoptosis and portal pressure in cirrhotic rats. External administration of IGF-1 increased the expressions of claudin-1 and occludin in enterocytes, and attenuated tight junction dysfunction in intestines of cirrhotic rats. LPS decreased TEER in Caco-2 cell monolayer. LPS also decreased claudin-1 and occludin expressions and increased apoptosis in Caco-2 cells. Furthermore, IGF-1 attenuated the effect of LPS on TEER, claudin-1 expression, occludin expression and apoptosis in Caco-2 cells.ConclusionsTight junction dysfunction develops during the development of liver cirrhosis, and endotoxemia will develop subsequently. Correspondingly, increased endotoxin in portal system worsens tight junction dysfunction via decreasing intestinal occludin and claudin-1 expressions and increasing enterocytic apoptosis. Endotoxemia and intestinal barrier dysfunction form a vicious circle. External administration of IGF-1 breaks this vicious circle. Improvement of tight junctions might be one possible mechanism of the restoration of intestinal barrier function mediated by IGF-1.

Effect of phosphorus on growth performance, intestinal tight junctions, Nrf2 signaling pathway and immune response of juvenile mirror carp (Cyprinus carpio) fed different α-ketoglutarate levels

Probiotic Bacteria Induce Maturation of Intestinal Claudin 3 Expression and Barrier Function

Effect of tea polyphenols (TP) on the quality of Chinese steamed bun (CSB) was investigated, while the interaction and action mechanism between TP and vital wheat gluten (VWG, constitutive proteins of flour) were further explored. With a low concentration (1%) of TP, CSB showed positive changes in quality, and the hardness of CSB decreased by 33.95%, while its specific volume, springiness, and resilience separately increased by 1.8%, 11.9%, and 5.5%, whereas the higher concentrations of TP (2% and 4%) caused an adverse impact. By observation of scanning electron microscope, VWG formed a fluffier structure with a low concentration of TP, while the structure deteriorated at high concentration of TP. In addition, the secondary and tertiary structures of VWG were both changed by TP. Along with the results of thermodynamic analysis (thermogravimetric and differential scanning calorimetry measurements), TP could induce the structural rearrangement of VWG. Further, a lower amidogen and sulfhydryl contents of VWG were obtained in TP groups, which illustrated that peptide and disulfide bonds of VWG were not possibly interrupted by TP. Instead, hydrophobic residues of VWG were bonded to form a more hydrophilic structure. Moreover, according to molecular docking results, epigallocatechin-3-gallate interacted tightly with VWG by hydrogen bonds and hydrophobic actions, and the action sites were mainly at hydrophobic and hydrophilic residues. All results suggested that the VWG structure was affected greatly by TP, and a low dose of TP might be potential to improve the quality of flour products. PRACTICAL APPLICATION: The physicochemical properties of gluten show the significant effects on the quality of flour products in food industry. In the present study, a low dose of tea polyphenols exhibited a strengthened effect on gluten, so as to ameliorate the texture of Chinese steamed bun (CSB) due to their tight interactions with gluten, while the color of CSB was changed to brown as tea polyphenols. All results suggested that a low dose of tea polyphenols could be potentially utilized to improve flour quality and enhance gluten strength in food industry.

To investigate the mechanism of autophagy in regulating bacterial translocation in intestinal infection caused by hypervirulent Klebsiella pneumonia (hvKp) and explore the method of reducing translocation infection of intestinal bacteria. Fifty C57BL/6J mice were divided into gavage group (n = 40) and control group (CO group, n = 10). The gavage group was orally administered with 200 μL/d of hvKp (colony count of 109 CFU/mL) continuously for 5 days to establish a hvKp intestinal infection model. CO group was given an equal amount of normal saline. After the experiment, the mice were anesthetized with lsofluraneand euthanized with cervical dislocation under anesthesia. Peripheral venous blood of mice was collected to detect bacterial translocation by 16S rDNA sequencing, then divided into translocation group (BT+ group) and non-translocation group (BT- group). Hematoxylin-eosin (HE) staining was used to evaluate intestinal morphology. The ultrastructural changes of intestinal tissues were observed by electron microscope. The levels of intestinal oxidative stress indicators such as superoxide dismutase (SOD), malondialdehyde (MDA) and glutathione peroxidase (GPx) were measured. Translocation was detected by in situ hybridization. The expression of tight junction protein microtubule-associated protein 1 light chain 3-II (LC3-II) and autophagy protein Beclin-1 were measured by Western blotting. The mRNA expression of tight junction proteins ZO-1 and Claudin-2 were detected by reverse transcription-polymerase chain reaction (RT-PCR). The expression of autophagy protein and tight junction protein were observed by immunofluorescence. Two out of 40 mice in the gavage group died after developing aspiration pneumonia. All mice in the CO group survived. The 16S rDNA sequencing results showed that no bacteria were detected in the peripheral blood of the CO group, but bacteria were detected in the peripheral blood of 18 mice in the gavage group, with a bacterial translocation rate of 47.4%. The BT- and BT+ groups showed intestinal mucosal tissue damage, with severe damage in the BT+ group. Compared with the CO group, the level of MDA in the BT- and BT+ groups were significantly increased, while the activities of SOD and GPx were significantly decreased. Compared with the BT- group, the MDA level in the BT+ group further increased, while the SOD and GPx activities further decreased [MDA (mmol/mg): 2.98±0.11 vs. 2.48±0.11, SOD (U/mg): 62.40±5.45 vs. 73.40±4.08, GPx (U/mg): 254.72±10.80 vs. 303.55±8.57, all P < 0.01]. The results of in situ hybridization detection showed that after continuous gastric lavage for 5 days, displaced hvKp was detected in the intestinal mucosal lamina propria and liver tissue of the BT+ group. Compared with the CO group, the protein expressions of LC3-II and Beclin-1 in the BT- and BT+ groups were significantly increased. The protein expressions of LC3-II and Beclin-1 in the BT+ group were obviously lower than those in the BT- group (LC3-II/β-actin: 0.38±0.04 vs. 0.70±0.09, Beclin-1/β-actin: 0.62±0.05 vs. 0.86±0.05, both P < 0.01), and there were autophagosomes in the intestinal mucosa. These results indicated that intestinal mucosal autophagy was activated after hvKp continuous gavage. Compared with CO group, the mRNA expressions of ZO-1 and Claudin-2 in the BT- and BT+ groups were significantly decreased. Compared with the BT- group, the mRNA expressions of ZO-1 and Claudin-2 in the BT+ group was further reduced [ZO-1 mRNA (2-ΔΔCT): 0.78±0.06 vs. 0.88±0.06, Claudin-2 mRNA (2-ΔΔCT): 0.40±0.04 vs. 0.70±0.06, both P < 0.01]. The immunofluorescence results showed that the fluorescence intensity of LC3-II, Beclin-1, ZO-1, and Claudin-2 in the BT+ group was significantly lower than that in the BT- group. HvKp can activate intestinal mucosal autophagy and reduce the damage to intestinal mucosal barrier function by down-regulating oxidative stress level, reduce the occurrence of bacterial translocation.