Toll-Like Receptor 4 Reduces Oxidative Injury via Glutathione Activity in Sheep

Emerging roles of toll-like receptor 4 in chemotherapy-induced neurotoxicity

Chemotherapy-induced neurotoxicity is one of the most prevalent side effects in cancer patients and survivors. Cognitive decline and peripheral neuropathy are the most common chemotherapy-induced neurotoxic symptoms. These symptoms lead not only to the limiting of the dose of chemotherapy given to cancer patients, but also have an impact on the quality of life of cancer survivors. Although the exact mechanisms involved in chemotherapy-induced neurotoxicity are still unclear, neuroinflammation is widely regarded as being one of the major causes involved in chemotherapy-induced neurotoxicity. It is known that Toll-like receptor 4 (TLR4) plays a critical role in the inflammatory process, and it has been recently reported that it is associated with chemotherapy-induced neurotoxicity. In this review, we summarize and discuss all available evidence regarding the activation of the TLR4 signaling pathway in various models of chemotherapy-induced neurotoxicity. This review also emphasizes the evidence pertinent to TLR4 inhibition on chemotherapy-induced neurotoxicity in rodent studies. Understanding the role of the TLR4 signaling pathway behind chemotherapy-induced neurotoxicity is crucial for improving treatments and ensuring the long-term survival of cancer patients.

Amino Acid Mutations in Hemagglutinin-Neuraminidase Enhance the Virulence and Pathogenicity of the Genotype III Newcastle Disease Vaccine Strain After Intravenous Inoculation

Newcastle disease virus (NDV), the causative agent that generally causes severe disease in poultry, continues to mutate and has thus evolved into 21 genotypes. We previously isolated a velogenic genotype III NDV JS/7/05/Ch that evolved from the vaccine strain Mukteswar, accompanying by amino acid mutations in Hemagglutinin-Neuraminidase (HN). Here, we sought to investigate the role of the mutant HN protein in NDV virulence. The HN genes of Mukteswar and JS/7/05/Ch were replaced reciprocally via reverse genetics, yielding two recombinant viruses rJS/MHN and rMu/JHN, respectively. rMu/JHN, in which the endogenous HN protein was replaced with the HN protein of JS/7/05/Ch, had a higher intravenous pathogenicity index (IVPI) value in chickens. Moreover, dual aa mutations (A494D and E495K from JS/7/05/Ch-type HN) were introduced into the HN protein of Mukteswar to generate the recombinant virus rMukHN494+495JS. This virus showed an equivalent IVPI value to that of rJS/7/05/Ch (generated from parental JS/7/05/Ch via reverse genetics). In vitro and in vivo assays further showed that A494D and E495K in HN induced antigenic changes, a higher replication level and a more intense inflammatory response. Taken together, these findings indicate that aa mutations in HN are crucial for the virulence of the genotype III Newcastle disease (ND) vaccine strain after intravenous inoculation. Our study further highlights that close surveillance is needed to monitor the genetic variation of ND vaccine strains.

Anti-Oxidant and Anti-Inflammatory Effects of Lipopolysaccharide from Rhodobacter sphaeroides against Ethanol-Induced Liver and Kidney Toxicity in Experimental Rats

This study aimed to investigate the protective effects of lipopolysaccharide from Rhodobacter sphaeroides (LPS-RS) against ethanol-induced hepatotoxicity and nephrotoxicity in experimental rats. The study involved an intact control group, LPS-RS group, two groups were given ethanol (3 and 5 g/kg/day) for 28 days, and two other groups (LPS-RS + 3 g/kg ethanol) and (LPS-RS + 5 g/kg ethanol) received a daily dose of LPS-RS (800 μg/kg) before ethanol. Ethanol significantly increased the expression of nuclear factor kappa B (NF-κB) and levels of malondialdehyde (MDA), tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) in the liver tissue and decreased anti-oxidant enzymes. Hepcidin expression was downregulated in the liver, with increased serum levels of ferritin and iron. Prior-administration of LPS-RS alleviated the increase in oxidative stress and inflammatory markers, and preserved iron homeostasis markers. In the kidney, administration of ethanol caused significant increase in the expression of NF-κB and the levels of TNF-α and kidney injury markers; whereas LPS-RS + ethanol groups had significantly lower levels of those parameters. In conclusion; this study reports anti-oxidant, anti-inflammatory and iron homeostasis regulatory effects of the toll-like receptor 4 (TLR4) antagonist LPS-RS against ethanol induced toxicity in both the liver and the kidney of experimental rats.

Terazosin reduces steroidogenic factor 1 and upregulates heat shock protein 90 expression in LH-induced bovine ovarian theca cells

Hyperthecosis syndrome is a common endocrine system metabolic disorder in women of childbearing age. The main symptoms are elevated androgen levels, abnormal ovulation, and excessive oxidative stress. Currently, there is no effective treatment for hyperthecosis syndrome. α(1)-adrenergic receptor (ADRA1) is involved in the metabolic pathway of ovarian steroid hormone. This study studied the mechanism of the ADRA1 inhibitor terazosin in the LH-induced bovine theca cells in vitro. We found that terazosin regulates the expression of steroidogenic factor 1 (SF1) and downstream genes through the ERK1/2 pathway, reducing androgen content. Terazosin promotes the expression of HSP90 and reduces the activity of iNOS. In addition, Terazosin up-regulates the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and its downstream gene γ-GCS, which improves the ability of theca cells to resist oxidative stress. This study provides a reference for the treatment of human hyperthecosis syndrome.

Evaluating the effect of TLR4-overexpressing on the transcriptome profile in ovine peripheral blood mononuclear cells

Background

Toll-like receptor 4 (TLR4) plays an important role in the elimination of Gram-negative bacteria infections and the initiation of antiinflammatory response. Using the technology of pronuclear microinjection, genetically modified (GM) sheep with TLR4 overexpression were generated. Previous studies have shown that these GM sheep exhibited a higher inflammatory response to Gram-negative bacteria infection than wild type (WT) sheep. In order to evaluate the gene expression of GM sheep and study the co-expressed and downstream genes for TLR4, peripheral blood mononuclear cells (PBMC) from TLR4-overexpressing (Tg) and wild type (WT) sheep were selected to discover the transcriptomic differences using RNA-Seq.

Result

An average of 18,754 and 19,530 known genes were identified in the Tg and WT libraries, respectively. A total of 338 known genes and 85 novel transcripts were found to be differentially expressed in the two libraries (p < 0.01). A differentially expressed genes (DEGs) enrichment analysis showed that the GO terms of inflammatory response, cell recognition, etc. were significantly (FDR < 0.05) enriched. Furthermore, the above DEGs were significantly (FDR < 0.05) enriched in the sole KEGG pathway of the Phagosome. Real-time PCR showed the OLR1, TLR4 and CD14 genes to be differentially expressed in the two groups, which validated the DEGs data.

Conclusions

The RNA-Seq results revealed that the overexpressed TLR4 in our experiment strengthened the ovine innate immune response by increasing the phagocytosis in PBMC.

Effects of TLR4 overexpression on sperm quality, seminal plasma biomarkers, sperm DNA methylation and pregnancy rate in sheep

Genetic modification provides a means to enhancing disease resistance in animals. In this study, the first generation of genetically modified (GM) sheep overexpressing TLR4 was produced by microinjection for better disease resistance. To compare semen characteristics including sperm quality, seminal plasma biochemical index, sperm DNA methylation and pregnancy rate of three-year old transgenic sheep with TLR4 overexpressed (toll like receptor 4, TLR4) and non-transgenic ram. Sixteen transgenic ram of F0 generation were produced by microinjection of the TLR4 plasmid into the pronucleus of fertilized ova. Seven transgenic sheep of F1 generation was produced by breeding F0 transgenic founders with non-transgenic sheep of the same breed. There were no significant differences between transgenic and control rams for all semen quality parameters, including semen volume, sperm concentration, sperm viability, and percentages of sperm with an intact plasma membrane, acrosomal integrity, and viable sperm with high mitochondrial membrane potential in both F0 and F1 generation. Furthermore, no significant differences were found for seminal plasma concentrations of zinc, neutral alpha-glucosidase, acid phosphatase or fructose, nor for levels of H19 and IGF2R methylation in sperm DNA. In addition, pregnancy rate was also similar between these two groups. In conclusion, there was no evidence that TLR4 overexpression altered the sperm quality, seminal plasma or sperm DNA of transgenic sheep.

Roles of Toll-Like Receptors in Nitroxidative Stress in Mammals

Free radicals are important antimicrobial effectors that cause damage to DNA, membrane lipids, and proteins. Professional phagocytes produce reactive oxygen species (ROS) and reactive nitrogen species (RNS) that contribute towards the destruction of pathogens. Toll-like receptors (TLRs) play a fundamental role in the innate immune response and respond to conserved microbial products and endogenous molecules resulting from cellular damage to elicit an effective defense against invading pathogens, tissue injury, or cancer. In recent years, several studies have focused on how the TLR-mediated activation of innate immune cells leads to the production of pro-inflammatory factors upon pathogen invasion. Here, we review recent findings that indicate that TLRs trigger a signaling cascade that induces the production of reactive oxygen and nitrogen species.

Role of Toll-like receptor 4/oxidant-coupled activation in regulating the biosynthesis of omega-3 polyunsaturated fatty acid derivative resolvin D1 in primary murine peritoneal macrophage

We have previously shown that reactive oxygen species (ROS) as prooxidants can activate Toll-like receptor 4 (TLR4) with the potential to initiate, propagate and maintain "sterile" inflammation of innate immunity, which plays a mediatory role in a host of human disease states. We now present new evidence that ROS can also activate TLR4 to counter the inflammatory phenotype by increasing the production of resolvin D1 (RvD1), which is a specialized anti-inflammatory and pro-resolving lipid mediator. We used primary murine peritoneal macrophages (pM) derived from both TLR4-WT and TLR4-KO mice as a cellular model. We used potassium peroxychromate (PPC) as a direct in vitro source of exogenous ROS. PPC treatment increased intracellular ROS levels, which decreased intracellular total antioxidant capacity, thus suggesting an enhanced cellular oxidative stress. PPC and LPS-EK (a TLR4-specific agonist) increased pro-inflammatory TNFα production with noeffect on IL-10, an anti-inflammatory cytokine. Treatment with the prooxidant increased the expression of 12 lipoxygenase (12-LOX) and 5-lipoxygenase (5-LOX) only in pM derived from TLR4 WT but not in pM from TLR4-KO mice. 5-LOX and 12-LOX are the key enzymes in the RvD1 biosynthetic pathway. In addition, PPC increased the expression of RvD1 receptor, a member of G-protein-coupled receptor only in pM from TLR4-WT mice. Our data support the involvement of TLR4-mediated oxidant-induced pro-inflammatory phenotypes that are in opposition to the production of anti-inflammatory/pro-resolution phenotypes in macrophages. Now, we show that through TLR4 activation, exogenous oxidants can play a role both in producing proinflammatory phenotypes at the same time that it enhances resolution of inflammation to maintain a state of cellular homeostasis and prevent tissue damage/disease.

Overexpression of Toll-like Receptor 4-linked Mitogen-activated Protein Kinase Signaling Contributes to Internalization of Escherichia coli in Sheep

Escherichia coli is one of the most common causal pathogens of mastitis in milk-producing mammals. Toll-like receptor 4 (TLR4) is important for host recognition of this bacteria. Increased activation of TLR4 can markedly enhance the internalization of E. coli. In this study, the relationship between TLR4 and mitogen-activated protein kinase (MAPK) signaling pathways in mediating E. coli internalization was evaluated in sheep monocytes. Using a TLR4-overexpressing transgenic (Tg) sheep model, we explored the bacterial internalization mechanism in sheep. We found that monocytes of Tg sheep could phagocytize more bacteria and exhibited higher adhesive capacity. The specific inhibition of p38 MAPK or c-Jun N-terminal kinase (JNK) or extracellular signal-regulated kinases (ERKs) reduced TLR4-dependent internalization of bacteria into sheep monocytes. Furthermore, the inhibition of MAPK signaling down-regulated the adhesive capacity of monocytes and the expression of scavenger receptors and adhesion molecules. Taken together, the overexpression of TLR4 in transgenic sheep enhanced the internalization of E. coli via MAPK signaling.

Melatonin reduces oxidative damage and upregulates heat shock protein 90 expression in cryopreserved human semen

Sperm cells can be damaged during the semen cryopreservation process, decreasing their fertilizing ability. Physical damage and oxidative stress may occur during the freeze-thawing process. Antioxidants such as the native antioxidant melatonin can potentially improve cryopreservation outcomes. In this study, we added melatonin to cryoprotectant to examine its effect on frozen-thawed human sperm. We found that adding 0.1mM melatonin to cryoprotectant significantly increased sperm viability (24.80 ± 0.46% vs. 20.97 ± 1.27%, P < 0.05) and membrane integrity (P < 0.05), and decreased intracellular reactive oxygen species and lipid peroxidation damage. Furthermore, mRNA levels of the transcription factor NF-E2-related factor-2 and its downstream genes were significantly increased. Resistance to oxidative stress was enhanced and expression of the antiapoptotic gene Bcl-2 was increased by inclusion of 0.1mM melatonin in the cryoprotectant. Moreover, 0.1mM melatonin upregulated the expression of heat shock protein 90 (HSP90), which confers resistance to stressors in frozen-thawed sperm. Results obtained upon addition of inhibitors of melatonin receptors (luzindole and 4-P-PDOT) and an HSP90 inhibitor (geldanamycin) in the cryoprotectant demonstrated that melatonin promoted HSP90 translation via the melatonin receptor MT1 and increased adenosine triphosphate levels, thus increasing the viability of thawed sperm.

Toll-Like Receptor 4 in Paraventricular Nucleus Mediates Visceral Hypersensitivity Induced by Maternal Separation

Neonatal maternal separation (MS) is a major early life stress that increases the risk of emotional disorders, visceral pain perception and other brain dysfunction. Elevation of toll-like receptor 4 (TLR4) signaling in the paraventricular nucleus (PVN) precipitates early life colorectal distension (CRD)-induced visceral hypersensitivity and pain in adulthood. The present study aimed to investigate the role of TLR4 signaling in the pathogenesis of postnatal MS-induced visceral hypersensitivity and pain during adulthood. The TLR4 gene was selectively knocked out in C57BL/10ScSn mice (Tlr4^-/-). MS was developed by housing the offspring alone for 6 h daily from postnatal day 2 to day 15. Visceral hypersensitivity and pain were assessed in adulthood. Tlr4^+/+, but not Tlr4^-/-, mice that had experienced neonatal MS showed chronic visceral hypersensitivity and pain. TLR4 immunoreactivity was observed predominately in microglia in the PVN, and MS was associated with an increase in the expression of protein and/or mRNA levels of TLR4, corticotropin-releasing factor (CRF), CRF receptor 1 (CRFR1), tumor necrosis factor-α, and interleukin-1β in Tlr4^+/+ mice. These alterations were not observed in Tlr4^-/- mice. Local administration of lipopolysaccharide, a TLR4 agonist, into the lateral cerebral ventricle elicited visceral hypersensitivity and TLR4 mRNA expression in the PVN, which could be prevented by NBI-35965, an antagonist to CRFR1. The present results indicate that neonatal MS induces a sensitization and upregulation of microglial TLR4 signaling activity, which facilitates the neighboring CRF neuronal activity and, eventually, precipitates visceral hypersensitivity in adulthood. Highlights (1)Neonatal MS does not induce chronic visceral hypersensitivity and pain in Tlr4^-/- mice.(2)Neonatal MS increases the expression of TLR4 mRNA, CRF protein and mRNA, CRFR1 protein, TNF-α protein, and IL-1β protein in Tlr4^+/+ mice.(3)TLR4 agonist LPS (i.c.v.) elicits visceral hypersensitivity and TLR4 mRNA expression in the PVN.