L-arginine reduces injury from heat stress to bovine intestinal epithelial cells by improving antioxidant and inflammatory response

Heat stress (HS) has a negative impact on the health and performance of dairy cows, resulting in economic losses. Damage to the intestinal epithelium is the main cause of the adverse effects of heat stress on bovine health. This study investigated the repair capability of L-arginine (L-Arg) in reducing the adverse effects of HS on bovine intestinal epithelial cells (BIECs). BIECs were treated as follows: (1) control cells were cultured at 37 °C continuously and received no L-Arg; (2) cells in HS group were grown at 42 °C for 6 h followed by 12 h at 37 °C; and (3) the L-Arg group was cultured at 42 °C for 6 h, then treated with L-Arg at 37 °C for 12 h. HS disrupted redox homeostasis and reduced viability in BIECs, while treatment with L-Arg (6 mmol/L) for 12 h markedly reduced the negative effects of HS. L-Arg protected cells by preventing HS-induced changes in mitochondrial membrane-potential, inflammation, apoptosis-related gene expression and regulation of antioxidant enzymes. The above results indicated that L-Arg reduced the level of damage from HS in BIECs by lowering oxidant stress and inflammation, suggesting that L-Arg could be an effective dietary addition to protect cows from adverse intestinal effects caused by HS.

Leucine protects bovine intestinal epithelial cells from hydrogen peroxide-induced apoptosis by alleviating oxidative damage

BACKGROUND

The present study aimed to investigate whether leucine (Leu) alleviates oxidative injury in bovine intestinal epithelial cells (BIECs) induced by hydrogen peroxide (H₂ O₂ ), as well as the underlying molecular mechanisms.

RESULTS

BIECs were treated with H₂ O₂ (1 mmol L^-1 ) and/or Leu (0, 0.9, 1.8 or 3.6 mmol L^-1 ) for 2 h. Leu increased cell viability (P < 0.05) and decreased the release of lactate dehydrogenase (P < 0.05) in BIECs challenged by H₂ O₂ . Then, the cells were treated with H₂ O₂ (1 mmol L^-1 ) and/or Leu (1.8 mmol L^-1 ) for 2 h. Compared with the H₂ O₂ group, cells treated with Leu and Leu + H₂ O₂ exhibited increased (P < 0.05) mRNA and protein expression of superoxide dismutase 2 (SOD2), catalase (CAT), glutathione peroxidase 1 (GPx1), heme oxygenase 1 (HO-1) and nuclear factor erythroid 2-related factor 2 (Nrf2). BIECs treatment with Leu significantly reduced (P < 0.05) apoptosis induced by H₂ O₂ . BIECs were transfected with Nrf2 small interfering RNA (siRNA) for 48 h and/or treated with H₂ O₂ (1 mmol L^-1 ) and/or Leu (1.8 mmol L^-1 ) for another 2 h. Transfection with Nrf2 siRNA abrogated the protective effect of Leu against H₂ O₂ -induced apoptosis and the mRNA and protein expression of SOD2 (P < 0.05).

CONCLUSION

These results indicate that Leu promotes the relative expression of antioxidant enzymes (SOD2, CAT and GPx1) and phase II detoxification enzymes (HO-1) by upregulating nuclear Nrf2 and activating the Nrf2 signaling pathway, thus enhancing the antioxidant capacity of cells. © 2022 Society of Chemical Industry.

Properties and regulation of Gly-Sar uptake and transport in bovine intestinal epithelial cells

Intestinal absorption of peptides is vital for the overall health and productivity of dairy cows. This study investigated the regulation, uptake and transport of dipeptides in bovine intestinal epithelial cells (BIECs). We also evaluated the effects of time, pH, concentration of the dipeptides, temperature, presence of diethylpyrocarbonate (DEPC)-an inhibitor of PepT1, and other dipeptides (Met-Met, Lys-Lys or Met-Lys), on the uptake and transport of Gly-Sar-FITC, which was a common fluorophore-labelled dipeptide. Under controlled experiments, BIECs were treated with 25 μM LY294002 (a phosphatidylinositol 3-kinase (PI3K) inhibitor) and 25 μM Perifosine (a protein kinase B (AKT) inhibitor). The subsequent expression of PepT1 in the BIECs was assessed by reverse transcriptase polymerase chain reaction (RT-PCR) and Western blotting. It was found that the uptake and transport of Gly-Sar-FITC were significant high at 37℃ than that at 4℃. The optimal pH for transport and uptake of Gly-Sar-FITC was 6.0-6.5, whereas the two properties decreased significantly in the presence of DEPC, Met-Met, Lys-Lys and Met-Lys (p < 0.05). The apical-to-basolateral transport was also found to be significantly higher than the reverse transport (p < 0.05). PI3K and AKT inhibitors were found to significantly suppress the expression of PepT1, thus impairing uptake and transport of Gly-Sar-FITC. Findings of this study thus suggest that the uptake and transport of Gly-Sar-FITC in BIECs are mediated by PepT1, and the PI3K/AKT signalling pathway regulates the absorption of small peptides.

Modulation of Toll-like receptor-mediated innate immunity in bovine intestinal epithelial cells by lactic acid bacteria isolated from feedlot cattle

The ability of lactobacilli isolated from feedlot cattle environment to differentially modulate the innate immune response triggered by Toll-like receptors (TLRs) activation in bovine intestinal epithelial (BIE) cells was evaluated. BIE cells were stimulated with Lactobacillus mucosae CRL2069, Lactobacillus acidophilus CRL2074, Lactobacillus fermentum CRL2085 or Lactobacillus rhamnosus CRL2084 and challenged with heat-stable pathogen associated molecular patterns (PAMPs) from enterotoxigenic Escherichia coli (ETEC) to induce the activation of TLR4 or with polyinosinic:polycytidylic acid (poly(I:C)) to activate TLR3. Type I interferons, cytokines, chemokines and negative regulators of TLR signalling were studied by RT-PCR. L. mucosae CRL2069 significantly reduced the expression of interleukin (IL)-8 and monocyte chemoattractant protein (MCP)-1 in BIE cells in the context of TLR3 activation. L. mucosae CRL2069 also reduced the expression of tumour necrosis factor-α, IL-β, MCP-1, and IL-8 in heat-stable ETEC PAMPs-challenged BIE cells. In addition, reduced expressions of IL-6, MCP-1, and IL-8 were found in BIE cells stimulated with L. rhamnosus CRL2084, although its effect was significantly lower than that observed for the CRL2069 strain. The reduced levels of pro-inflammatory factors in BIE cells induced by the CRL2069 and CRL2085 strains was related to their ability of increasing the expression of TLR negative regulators. L. mucosae CRL2069 significantly improved the expression of A20-binding inhibitor of NFκ-B activation 3 (ABIN-3), interleukin-1 receptor-associated kinase M (IRAK-M) and mitogen-activated protein kinase 1 (MKP-1) while L. rhamnosus CRL2084 augmented ABIN-3 expression in BIE cells. The results of this work suggest that among the studied strains, L. mucosae CRL2069 was able to regulate TLR3-mediated innate immune response and showed a remarkable capacity to modulate TLR4-mediated inflammation in BIE cells. The CRL2069 strain induce the up-regulation of three TLR negative regulators that would influence nuclear factor kB and mitogen-activated protein kinases signalling pathways while reducing the expression of pro-inflammatory cytokines and chemokines. Therefore, L. mucosae CRL2069 is an interesting immunobiotic candidate for the protection of the bovine host against TLR-mediated intestinal inflammatory damage.

Deciphering the influence of paraimmunobiotic bifidobacteria on the innate antiviral immune response of bovine intestinal epitheliocytes by transcriptomic analysis

Previously, we reported that the non-viable immunomodulatory Bifidobacterium infantis MCC12 and Bifidobacterium breve MCC1274 strains (paraimmunobiotic bifidobacteria) were able to increase the protection against rotavirus infection in bovine intestinal epithelial (BIE) cells. In order to gain insight into the influence of paraimmunobiotic bifidobacteria on the innate antiviral immune response of BIE cells, their effect on the transcriptomic response triggered by Toll-like receptor 3 (TLR3) activation was investigated. By using microarray technology and qPCR analysis, we obtained a global overview of the immune genes involved in the innate antiviral immune response in BIE cells. Activation of TLR3 by poly(I:C) in BIE cells significantly increased the expression of interferon (IFN)-α and IFN-β, several interferon-stimulated genes, cytokines, and chemokines. It was also observed that both paraimmunobiotic bifidobacteria differently modulated immune genes expression in poly(I:C)-challenged BIE cells. Most notable changes were found in genes involved in antiviral defence (IFN-β, MX1, OAS1X, MDA5, TLR3, STAT2, STAT3), cytokines (interleukin (IL)-6), and chemokines (CCL2, CXCL2, CXCL6) that were significantly increased in bifidobacteria-treated BIE cells. B. infantis MCC12 and B. breve MCC1274 showed quantitative and qualitative differences in their capacities to modulate the innate antiviral immune response in BIE cells. B. breve MCC1274 was more efficient than the MCC12 strain to improve the production of type I IFNs and antiviral factors, an effect that could be related to its higher ability to protect against rotavirus replication in BIE cells. Interestingly, B. infantis MCC12 showed a remarkable anti-inflammatory effect. The MCC12 strain was more efficient to reduce the expression of inflammatory cytokines and chemokines (IL-16, IL-20, CX3CL1) when compared with B. breve MCC1274. These results provided valuable information for the deeper understanding of the antiviral immune response of intestinal epithelial cells as well as the host-paraimmunobiotic interaction in the bovine host.

Development of an in vitro immunobiotic evaluation system against rotavirus infection in bovine intestinal epitheliocytes

The bovine intestinal epithelial cell line (BIE cells) expresses the Toll-like receptor (TLR)3 and is able to mount an antiviral immune response after the stimulation with poly(I:C). In the present study, we aimed to further characterise the antiviral defence mechanisms in BIE cells by evaluating the innate immune response triggered by rotavirus (RV) infection. In addition, we attempted to determine whether immunobiotic bifidobacteria are able to confer protection of BIE cells against RV infection by beneficially modulating the antiviral immune response. RV OSU (porcine) and UK (bovine) effectively infected BIE cells, while a significant lower capacity to infect BIE cells was observed for human (Wa) and murine (EW) RV. We observed that viral infection in BIE cells triggered TLR3/RIG-I-mediated immune responses with activation of IRF3 and TRAF3, induction of interferon beta (IFN-β) and up-regulation of inflammatory cytokines. Our results also demonstrated that preventive treatments with Bifidobacterium infantis MCC12 or Bifidobacterium breve MCC1274 significantly reduced RV titres in infected BIE cells and differentially modulated the innate immune response. Of note, both strains significantly improved the production of the antiviral factor IFN-β in RV-infected BIE cells. In conclusion, this work provides comprehensive information on the antiviral immune response of BIE cells against RV, that can be further studied for the development of strategies aimed to improve antiviral defences in bovine intestinal epithelial cells. Our results also demonstrate that BIE cells could be used as a newly immunobiotic evaluation system against RV infection for application in the bovine host.

Advanced application of bovine intestinal epithelial cell line for evaluating regulatory effect of lactobacilli against heat-killed enterotoxigenic Escherichia coli-mediated inflammation

BACKGROUND

Previously, a bovine intestinal epithelial cell line (BIE cells) was successfully established. This work hypothesized that BIE cells are useful in vitro model system for the study of interactions of microbial- or pathogen-associated molecular patterns (MAMPs or PAMPs) with bovine intestinal epithelial cells and for the selection of immunoregulatory lactic acid bacteria (LAB).

RESULTS

All toll-like receptor (TLR) genes were expressed in BIE cells, being TLR4 one of the most strongly expressed. We demonstrated that heat-stable PAMPs of enterotoxigenic Escherichia coli (ETEC) significantly enhanced the production of IL-6, IL-8, IL-1α and MCP-1 in BIE cells by activating both NF-κB and MAPK pathways. We evaluated the capacity of several lactobacilli strains to modulate heat-stable ETEC PAMPs-mediated inflammatory response in BIE cells. Among these strains evaluated, Lactobacillus casei OLL2768 attenuated heat-stable ETEC PAMPs-induced pro-inflammatory response by inhibiting NF-κB and p38 signaling pathways in BIE cells. Moreover, L. casei OLL2768 negatively regulated TLR4 signaling in BIE cells by up-regulating Toll interacting protein (Tollip) and B-cell lymphoma 3-encoded protein (Bcl-3).

CONCLUSIONS

BIE cells are suitable for the selection of immunoregulatory LAB and for studying the mechanisms involved in the protective activity of immunobiotics against pathogen-induced inflammatory damage. In addition, we showed that L. casei OLL2768 functionally modulate the bovine intestinal epithelium by attenuating heat-stable ETEC PAMPs-induced inflammation. Therefore L. casei OLL2768 is a good candidate for in vivo studying the protective effect of LAB against intestinal inflammatory damage induced by ETEC infection or heat-stable ETEC PAMPs challenge in the bovine host.