Regulation of Toll-like receptor signaling pathways in innate immune responses

The novel fish miRNA, Soc-miR-118, functions as a negative regulator in NF-κB-mediated inflammation by targeting IL-6 in teleost fish

Inflammation is initiated as a protective response of the organism to remove invading bacterial and initiate the healing process. Prolonged inflammation and excessive production of inflammatory cytokines lead to inflammatory disorders or autoimmune diseases. Thus, different layers of negative regulators are needed to achieve balances between protective immunity and inflammatory pathology. Accumulating evidences show that miRNAs act as significant and multifunctional regulators involved in regulating networks of host-pathogen interactions. However, the functions and mechanisms of miRNAs in directly targeting and regulating inflammatory cytokines remains largely unknown in lower vertebrates. In this study, we report a novel miRNA, Soc-miR-118, identified from Sciaenops ocellatus, which plays a negative role in antibacterial immunity by regulating Interleukin-6 (IL-6). Specifically, we found that Soc-miR-118 directly targets IL-6 and suppresses the production of inflammatory cytokines through the NF-κB signaling pathway, thereby avoiding excessive inflammatory response. Particularly, the mechanism by which Soc-miR-118 regulates IL-6 expression also exist in other fish, suggesting that the miRNA in fish has evolutionarily conserved regulatory systems. The collective results that Soc-miR-118 acts as a negative regulator involved in host antibacterial immunity through directly regulating inflammatory cytokines, will greatly enrich the intricate networks of host-pathogen interaction in lower vertebrates.

Bioelectric medicine: unveiling the therapeutic potential of micro-current stimulation

Bioelectric medicine (BEM) refers to the use of electrical signals to modulate the electrical activity of cells and tissues in the body for therapeutic purposes. In this review, we particularly focused on the microcurrent stimulation (MCS), because, this can take place at the cellular level with sub-sensory application unlike other stimuli. These extremely low-level currents mimic the body's natural electrical activity and are believed to promote various physiological processes. To date, MCS has limited use in the field of BEM with applications in several therapeutic purposes. However, recent studies provide hopeful signs that MCS is more scalable and widely applicable than what has been used so far. Therefore, this review delves into the landscape of MCS, shedding light on the multifaceted applications and untapped potential of MCS in the realm of healthcare. Particularly, we summarized the hierarchical mediation from cell to whole body responses by MCS including its physiological applications. Our final objective of this review is to contribute to the growing body of literature that unveils the captivating potential of BEM, with MCS poised at the intersection of technological innovation and the intricacies of the human body.

Toll-like receptor signaling pathway involved in pathogenesis of thromboangiitis obliterans through activating of NF-κB

OBJECTIVES

The pathogenic mechanisms of Thromboangiitis Obliterans (TAO) are not entirely known and autoimmune inflammation plays a vital role in the initiation and continuance of TAO activity. The authors investigated in this study the role of the TLR signaling pathway in the pathogenesis of TAO.

METHODS

First, the authors detected the expressions of MyD88, TRIF and NF-κB in vascular walls of 46 patients with TAO and 32 patients with trauma and osteosarcoma by western blot assay. Second, the authors detected the cellular localization of MyD88, TRIF and NF-κB in vascular walls of patients with TAO by immunofluorescent assay.

RESULTS

The protein expressions of MyD88, TRIF and NF-κB were much higher in vascular walls of TAO patients (p < 0.05). Higher expressions of MyD88 and NF-κB were detected both on vascular endothelial and vascular smooth muscle cells of TAO patients. However, higher expression of TRIF was just detected on vascular smooth muscle cells of TAO patients.

CONCLUSIONS

These dates suggest that the TLR signaling pathway might play an important role in the pathogenesis of TAO, it might induce vasospasm, vasculitis and thrombogenesis to lead to the pathogenesis and progression of TAO.

Moderate altitude exposure impacts host fasting blood glucose and serum metabolome by regulation of the intestinal flora

Moderate altitude exposure has shown beneficial effects on diabetes incidence but the underlying mechanisms are not understood. Our study aimed to investigate how the human gut microbiome impacted the serum metabolome and associated with glucose homeostasis in healthy Chinese individuals upon moderate-altitude exposure. Faecal microbiome composition was assessed using shotgun metagenomic sequencing. Serum metabolome was acquired by untargeted metabolomics technology, and amino acids (AAs) and propionic acid in serum were quantified by targeted metabolomics technology. The results indicated that the moderate-altitude exposed individuals presented lowered fasting blood glucose (FBG) and propionic acid, increased circulating L-Glutamine but decreased L-Glutamate and L-Valine, which correlated with enriched Bacteroidetes and decreased Proteobacteria. Additionally, the silico causality associations among gut microbiota, serum metabolome and host FBG were analyzed by mediation analysis. It showed that increased Bacteroides ovatus (B. ovatus) and decreased Escherichia coli (E. coli) were identified as the main antagonistic species driving the association between L-Glutamate and FBG in silico causality. Furthermore, the high-fat diet (HFD) fed mice subjected to faecal microbiota transplantation (FMT) were applied to validate the cause-in-fact effects of gut microbiota on the beneficial glucose response. We found that microbiome in the moderate-altitude exposed donor could predict the extent of the FBG response in recipient mice, which showed lowered FBG, L-Glutamate and Firmicutes/Bacteroidetes ratio. Our findings suggest that moderate-altitude exposure targeting gut microbiota and circulating metabolome, may pave novel avenues to counter dysglycemia.

DAMPs and alarmin gene expression patterns in aging healthy and diseased mucosal tissues

Introduction

Periodontitis is delineated by a dysbiotic microbiome at sites of lesions accompanied by a dysregulated persistent inflammatory response that undermines the integrity of the periodontium. The interplay of the altered microbial ecology and warning signals from host cells would be a critical feature for maintaining or re-establishing homeostasis in these tissues.

Methods

This study used a nonhuman primate model (Macaca mulatta) with naturally-occurring periodontitis (n = 34) and experimental ligature-induced periodontitis (n = 36) to describe the features of gene expression for an array of damage-associate molecular patterns (DAMPs) or alarmins within the gingival tissues. The animals were age stratified into: ≤3 years (Young), 7-12 years (Adolescent), 12-15 years (Adult) and 17-23 years (Aged). Gingival tissue biopsies were examined via microarray. The analysis focused on 51 genes representative of the DAMPs/alarmins family of host cell warning factors and 18 genes associated with tissue destructive processed in the gingival tissues. Bacterial plaque samples were collected by curette sampling and 16S rRNA gene sequences used to describe the oral microbiome.

Results

A subset of DAMPs/alarmins were expressed in healthy and naturally-occurring periodontitis tissues in the animals and suggested local effects on gingival tissues leading to altered levels of DAMPs/alarmins related to age and disease. Significant differences from adult healthy levels were most frequently observed in the young and adolescent animals with few representatives in this gene array altered in the healthy aged gingival tissues. Of the 51 target genes, only approximately ⅓ were altered by ≥1.5-fold in any of the age groups of animals during disease, with those increases observed during disease initiation. Distinctive positive and negative correlations were noted with the DAMP/alarmin gene levels and comparative expression changes of tissue destructive molecules during disease across the age groups. Finally, specific correlations of DAMP/alarmin genes and relative abundance of particular microbes were observed in health and resolution samples in younger animals, while increased correlations during disease in the older groups were noted.

Conclusions

Thus, using this human-like preclinical model of induced periodontitis, we demonstrated the dynamics of the activation of the DAMP/alarmin warning system in the gingival tissues that showed some specific differences based on age.

MicroRNA-Mediated Host Immune Genes Manipulation Benefits AcMNPV Proliferation in Spodoptera frugiperda

Spodoptera frugiperda is a highly destructive migratory pest that threatens various crops globally. Autographa californica multiple nucleopolyhedrovirus (AcMNPV) is an effective biocontrol agent against lepidopteran pests. Here, we explored the molecular mechanisms underlying the immune response to AcMNPV infection in S. frugiperda. RNA-seq and quantitative reverse transcription-polymerase chain reaction (qRT-PCR) analyses identified the Toll, IMD, and apoptosis pathways as primary immune responses. Investigation into AcMNPV-induced apoptosis in the S. frugiperda cell line (Sf9) revealed that the Toll pathway activated the JNK via the TRAF6 (TNF receptor-associated factor 6) adapter. In addition, AcMNPV-induced the differential expression of several host-encoded microRNAs (miRNAs), with significant negative regulatory effects, on S. frugiperda antiviral immune genes. RNAi and miRNA-mimic mediated silencing of these genes resulted in increased AcMNPV proliferation. Our findings reinforce the potential of AcMNPV as a potent biocontrol agent and further our understanding of developing biotechnology-based targeted pest control agents.

Quercetin Alleviates Lipopolysaccharide-Induced Cell Oxidative Stress and Inflammatory Responses via Regulation of the TLR4-NF-κB Signaling Pathway in Bovine Rumen Epithelial Cells

Subacute rumen acidosis (SARA) will cause an increase in endotoxin, which will have a negative effect on the bovine rumen epithelial cells (BREC). Flavonoids are effective in treating inflammation caused by endotoxin. Quercetin is a vital flavonoid widely occurring in fruits and vegetables and has received significant interest as a prospective anti-inflammatory antioxidant. Nonetheless, quercetin's protective machinery against such damage to BREC induced by lipopolysaccharide (LPS) remains unclear. A combined quercetin and LPS-induced BREC inflammation model was utilized to elucidate the effect of quercetin protecting BREC from LPS-induced injury. After treating BREC with different doses of LPS (1, 5, and 10 μg/mL) for 6 h or 24 h, the mRNA expression of inflammatory factors was detected. Our experimental results show the establishment of the BREC inflammation model via mRNA high expression of pro-inflammatory cytokines in BREC following 6 h treatment with 1 µg/mL LPS. The promotive effect of 80 μg/mL quercetin on BREC growth via the cell counting kit-8 (CCK8) assay was observed. The expression of pro-inflammatory cytokines and chemokines, notably tumor necrosis factor α (TNF-α), Interleukin 1β (IL-1β), IL-6, CC-motif chemokine ligand 2 (CCL2), CCL20, CCL28, and CXC motif chemokine 9 (CXCL9), etc., was significantly reduced by quercetin supplementation. We also analyzed the mRNA detection of related pathways by qRT-PCR. Our validation studies demonstrated that quercetin markedly curbed the mRNA expression of the toll-like receptor 4 (TLR4) and myeloid differentiation primary response protein (MyD88) and the nuclear factor-κB (NF-κB) in LPS-treated BREC. In addition, western blot result outcomes confirmed, as expected, that LPS significantly activated phosphorylation of p44/42 extracellular regulated protein kinases (ERK1/2) and NF-κB. Unexpectedly, this effect was reversed by adding quercetin. To complement western blot results, we assessed p-ERK1/2 and p-p65 protein expression using immunofluorescence, which gave consistent results. Therefore, quercetin's capacity to bar the TLR4-mediated NF-κB and MAPK signaling pathways may be the cause of its anti-inflammatory effects on LPS-induced inflammatory reactions in BREC. According to these results, quercetin may be utilized as an anti-inflammatory medication to alleviate inflammation brought on by high-grain feed, and it also lays out a conceptual foundation regarding the development and utilization of quercetin in the later stage.

Brain alarm by self-extracellular nucleic acids: from neuroinflammation to neurodegeneration

Neurological disorders such as stroke, multiple sclerosis, as well as the neurodegenerative diseases Parkinson's or Alzheimer's disease are accompanied or even powered by danger associated molecular patterns (DAMPs), defined as endogenous molecules released from stressed or damaged tissue. Besides protein-related DAMPs or "alarmins", numerous nucleic acid DAMPs exist in body fluids, such as cell-free nuclear and mitochondrial DNA as well as different species of extracellular RNA, collectively termed as self-extracellular nucleic acids (SENAs). Among these, microRNA, long non-coding RNAs, circular RNAs and extracellular ribosomal RNA constitute the majority of RNA-based DAMPs. Upon tissue injury, necrosis or apoptosis, such SENAs are released from neuronal, immune and other cells predominantly in association with extracellular vesicles and may be translocated to target cells where they can induce intracellular regulatory pathways in gene transcription and translation. The majority of SENA-induced signaling reactions in the brain appear to be related to neuroinflammatory processes, often causally associated with the onset or progression of the respective disease. In this review, the impact of the diverse types of SENAs on neuroinflammatory and neurodegenerative diseases will be discussed. Based on the accumulating knowledge in this field, several specific antagonistic approaches are presented that could serve as therapeutic interventions to lower the pathological outcome of the indicated brain disorders.

Therapeutic implication of Sonic Hedgehog as a potential modulator in ischemic injury

Sonic Hedgehog (SHh) is a homology protein that is involved in the modeling and development of embryonic tissues. As SHh plays both protective and harmful roles in ischemia, any disruption in the transduction and regulation of the SHh signaling pathway causes ischemia to worsen. The SHh signal activation occurs when SHh binds to the receptor complex of Ptc-mediated Smoothened (Smo) (Ptc-smo), which initiates the downstream signaling cascade. This article will shed light on how pharmacological modifications to the SHh signaling pathway transduction mechanism alter ischemic conditions via canonical and non-canonical pathways by activating certain downstream signaling cascades with respect to protein kinase pathways, angiogenic cytokines, inflammatory mediators, oxidative parameters, and apoptotic pathways. The canonical pathway includes direct activation of interleukins (ILs), angiogenic cytokines like hepatocyte growth factor (HGF), platelet-derived growth factor (PDGF), vascular endothelial growth factor (VEGF), epidermal growth factor (EGF), and hypoxia-inducible factor alpha (HIF-), which modulate ischemia. The non-canonical pathway includes indirect activation of certain pathways like mTOR, PI3K/Akt, MAPK, RhoA/ROCK, Wnt/-catenin, NOTCH, Forkhead box protein (FOXF), Toll-like receptors (TLR), oxidative parameters such as GSH, SOD, and CAT, and some apoptotic parameters such as Bcl2. This review provides comprehensive insights that contribute to our knowledge of how SHh impacts the progression and outcomes of ischemic injuries.

Transcriptomic Analysis of mRNA Expression Profiles in the Microglia of Mouse Brains Infected with Rabies Viruses of Varying Virulence

Rabies is a lethal encephalitis caused by the rabies virus (RABV) with a fatality rate near 100% after the onset of clinical symptoms in humans and animals. Microglia are resident immune cells in the central nervous system. Few studies have been conducted on the functional role of microglia in RABV infection. Here, we performed a transcriptomic analysis of mRNA expression profiles in the microglia of mouse brains intracerebrally infected with RABV. We successfully isolated single microglial cells from the mouse brains. The survival rate of dissociated microglial cells was 81.91%-96.7%, and the purity was 88.3%. Transcriptomic analysis revealed 22,079 differentially expressed mRNAs identified in the microglia of mouse brains infected with RABV strains (rRC-HL, GX074, and CVS-24) of varying virulence at 4 and 7 days post-infection (dpi) compared to the control group. The numbers of DEGs versus the control at 4 and 7 dpi in mice infected with rRC-HL, GX074, and CVS-24 were 3622 and 4590, 265 and 4901, and 4079 and 6337. The GO enrichment analysis showed that response to stress, response to external stimulus, regulation of response to stimulus, and immune system process were abundant during RABV infection. The KEGG analysis indicated that the Tlr, Tnf, RIG-I, NOD, NF-κB, MAPK, and Jak-STAT signaling pathways were involved in RABV infection at both 4 and 7 dpi. However, some phagocytosis and cell signal transduction processes, such as endocytosis, p53, phospholipase D, and oxidative phosphorylation signaling pathways, were only expressed at 7 dpi. The involvement of the Tnf and Tlr signaling pathways prompted us to construct a protein-protein interaction (PPI) network of these pathways. The PPI revealed 8 DEGs, including Mmp9, Jun, Pik3r1, and Mapk12. Notably, Il-1b interacted with Tnf and Il-6 with combined scores of 0.973 and 0.981, respectively. RABV causes significant changes in mRNA expression profiles in the microglia in mice. 22,079 differentially expressed mRNAs were identified in the microglia of mice infected with RABV strains of varying virulence at 4 and 7 dpi. The DEGs were evaluated using GO, KEGG, and PPI network analysis. Many immune pathways were up-regulated in RABV-infected groups. The findings will help elucidate the microglial molecular mechanisms of cellular metabolism dysregulated by RABV and may provide important information for investigating RABV pathogenesis and therapeutic methods.

Schizophrenia and obesity: May the gut microbiota serve as a link for the pathogenesis?

Schizophrenia (SZ) places a tremendous burden on public health as one of the leading causes of disability and death. SZ patients are more prone to developing obesity than the general population from the clinical practice. The development of obesity frequently causes poor psychiatric outcomes in SZ patients. In turn, maternal obesity during pregnancy has been associated with an increased risk of SZ in offspring, suggesting that these two disorders may have shared neuropathological mechanisms. The gut microbiota is well known to serve as a major regulator of bidirectional interactions between the central nervous system and the gastrointestinal tract. It also plays a critical role in maintaining physical and mental health in humans. Recent studies have shown that the dysbiosis of gut microbiota is intimately associated with the onset of SZ and obesity through shared pathophysiological mechanisms, particularly the stimulation of immune inflammation. Therefore, gut microbiota may serve as a common biological basis for the etiology in both SZ and obesity, and the perturbed gut-brain axis may therefore account for the high prevalence of obesity in patients with SZ. On the basis of these findings, this review provides updated perspectives and intervention approaches on the etiology, prevention, and management of obesity in SZ patients by summarizing the recent findings on the role of gut microbiota in the pathogenesis of SZ and obesity, highlighting the role of gut-derived inflammation.

Functions and cellular signaling by ribosomal extracellular RNA (rexRNA): Facts and hypotheses on a non-typical DAMP

Upon microbial infections with the subsequent host response of innate immunity, a variety of fragmented RNA- and DNA-based "Pathogen-associated molecular patterns" (PAMPs) are recognized mainly by endosomal or cytoplasmic host cell "Pattern recognition receptors" (PRRs), particularly "Toll-like receptors" (TLRs). Concomitantly, various self-extracellular RNA species (exRNAs) are present in extracellular body fluids where they contribute to diverse physiological and homeostatic processes. In principle, such exRNAs, including the most abundant one, ribosomal exRNA (rexRNA), are designated as "Danger-associated molecular patterns" (DAMPs) and are prevented by e.g. natural modifications from uncontrolled signaling via TLRs to avoid hyper-inflammatory responses or autoimmunity. Upon cellular stress or tissue damage/necrosis, the levels and composition of released self-exRNA species, either in free form, in complex with proteins or in association with extracellular vesicles (EVs), can change considerably. Among the self-exRNAs, rexRNA is considered as a non-typical DAMP, since it may induce inflammatory responses by cell membrane receptors, both in the absence or presence of PAMPs. Yet, its mode of receptor activation to mount inflammatory responses remains obscure. RexRNA also serves as a universal damaging factor in cardiovascular and other diseases independent of PRRs. In general, RNase1 provides a profound antagonist in these pathologies and in rexRNA-mediated inflammatory cell responses. Based on the extrapolation of the here described aspects of rexRNA-biology, further activities of this molecular entity are hypothesized that may stimulate additional research in this area.

Parallel repair mechanisms in plants and animals

All organisms have acquired mechanisms for repairing themselves after accidents or lucky escape from predators, but how analogous are these mechanisms across phyla? Plants and animals are distant relatives in the tree of life, but both need to be able to efficiently repair themselves, or they will perish. Both have an outer epidermal barrier layer and a circulatory system that they must protect from infection. However, plant cells are immotile with rigid cell walls, so they cannot raise an animal-like immune response or move away from the insult, as animals can. Here, we discuss the parallel strategies and signalling pathways used by plants and animals to heal their tissues, as well as key differences. A more comprehensive understanding of these parallels and differences could highlight potential avenues to enhance healing of patients' wounds in the clinic and, in a reciprocal way, for developing novel alternatives to agricultural pesticides.

Toll-like receptors 7 and 9 regulate the proliferation and differentiation of B cells in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune illness marked by the loss of immune tolerance and the production of autoantibodies against nucleic acids and other nuclear antigens (Ags). B lymphocytes are important in the immunopathogenesis of SLE. Multiple receptors control abnormal B-cell activation in SLE patients, including intrinsic Toll-like receptors (TLRs), B-cell receptors (BCRs), and cytokine receptors. The role of TLRs, notably TLR7 and TLR9, in the pathophysiology of SLE has been extensively explored in recent years. When endogenous or exogenous nucleic acid ligands are recognized by BCRs and internalized into B cells, they bind TLR7 or TLR9 to activate related signalling pathways and thus govern the proliferation and differentiation of B cells. Surprisingly, TLR7 and TLR9 appear to play opposing roles in SLE B cells, and the interaction between them is still poorly understood. In addition, other cells can enhance TLR signalling in B cells of SLE patients by releasing cytokines that accelerate the differentiation of B cells into plasma cells. Therefore, the delineation of how TLR7 and TLR9 regulate the abnormal activation of B cells in SLE may aid the understanding of the mechanisms of SLE and provide directions for TLR-targeted therapies for SLE.

Identification of key genes and imbalance of immune cell infiltration in immunoglobulin A associated vasculitis nephritis by integrated bioinformatic analysis

Background

IgAV, the most common systemic vasculitis in childhood, is an immunoglobulin A-associated immune complex-mediated disease and its underlying molecular mechanisms are not fully understood. This study attempted to identify differentially expressed genes (DEGs) and find dysregulated immune cell types in IgAV to find the underlying pathogenesis for IgAVN.

Methods

GSE102114 datasets were obtained from the Gene Expression Omnibus (GEO) database to identify DEGs. Then, the protein-protein interaction (PPI) network of the DEGs was constructed using the STRING database. And key hub genes were identified by cytoHubba plug-in, performed functional enrichment analyses and followed by verification using PCR based on patient samples. Finally, the abundance of 24 immune cells were detected by Immune Cell Abundance Identifier (ImmuCellAI) to estimate the proportions and dysregulation of immune cell types within IgAVN.

Result

A total of 4200 DEGs were screened in IgAVN patients compared to Health Donor, including 2004 upregulated and 2196 downregulated genes. Of the top 10 hub genes from PPI network, STAT1, TLR4, PTEN, UBB, HSPA8, ATP5B, UBA52, and CDC42 were verified significantly upregulated in more patients. Enrichment analyses indicated that hub genes were primarily enriched in Toll-like receptor (TLR) signaling pathway, nucleotide oligomerization domain (NOD)-like receptor signaling pathway, and Th17 signaling pathways. Moreover, we found a diversity of immune cells in IgAVN, consisting mainly of T cells. Finally, this study suggests that the overdifferentiation of Th2 cells, Th17 cells and Tfh cells may be involved in the occurrence and development of IgAVN.

Conclusion

We screened out the key genes, pathways and maladjusted immune cells and associated with the pathogenesis of IgAVN. The unique characteristics of IgAV-infiltrating immune cell subsets were confirmed, providing new insights for future molecular targeted therapy and a direction for immunological research on IgAVN.

Toll-like Receptors and Celiac Disease

Celiac disease (CD) is an immune-mediated disorder triggered by dietary gluten intake in some genetically predisposed individuals; however, the additional non-HLA-related genetic factors implicated in CD immunopathogenesis are not well-defined. The role of the innate immune system in autoimmunity has emerged in the last few years. Genetic polymorphisms of some pattern-recognition receptors, including toll-like receptors (TLRs), have been associated with several autoimmune disorders. In this review, we summarize and discuss the evidence from basic research and clinical studies as regards the potential role of TLRs in CD immunopathogenesis. The evidence supporting the role of TLRs in CD immunopathogenesis is limited, especially in terms of basic research. However, differences in the expression and activation of TLRs between active CD patients from one side, and controls and treated CD patients from the other side, have been described in some clinical studies. Therefore, TLRs may be part of those non-HLA-related genetic factors implicated in CD etiopathogenesis, considering their potential role in the interaction between the host immune system and some environmental factors (including viral infections and gut microbiota), which are included in the list of candidate agents potentially contributing to the determination of CD risk in genetically predisposed individuals exposed to dietary gluten intake. Further basic research and clinical studies focused on TLRs in the context of CD and other gluten-related disorders are needed.

The impact of Hyssop (Hyssopus officinalis) extract on activation of endosomal toll like receptors and their downstream signaling pathways

OBJECTIVES

From the ancient, medicinal benefits of Hyssop (Hyssopus officinalis L.) have been implicated for respiratory and digestive diseases despite the effects of Hyssop on viral infections have not been mechanistically investigated. In this study, we examined whether the Hyssop extract activated anti-viral innate immunity, as a sentinel for immune system, through activation of endosomal TLRs recognizing nucleic acids and their downstream signaling. The Hyssop herb extracts was prepared and co-cultured with healthy individual's peripheral blood mononuclear cells (PBMCs). After viability assay, gene expression levels of TLR3,7,8,9, as well as MyD88 and NF-κB, were evaluated in treated PBMCs using Real-time PCR. Next, the secretion level of immune related cytokines was quantified via ELISA.

RESULTS

Post 24 h, 40 µg/ml of the extract significantly inhibited the viability of less than 50% of cells compared to the control and had a maximum effect on cellular function. The Hyssop-treated PBMCs demonstrated an elevated expression of endosomal TLRs genes, as well as MyD88 and NF-κB. Moreover, the release of INF-α and β notably enhanced in cell culture supernatant, while the content of inflammatory cytokines remarkably diminished (P < 0.05). The Hyssop extract was capable of inducing antiviral innate immune responses so can be promising in antiviral drug strategies.

Quercetin Alleviates Lipopolysaccharide-Induced Cell Damage and Inflammation via Regulation of the TLR4/NF-κB Pathway in Bovine Intestinal Epithelial Cells

Acute diarrhoea and intestinal inflammation represent one of the most prevalent clinical disorders of milk production, resulting in enormous annual financial damage for the dairy sector. In the context of an unsatisfactory therapeutic effect of antibiotics, the natural products of plants have been the focus of research. Quercetin is an important flavonoid found in a variety of plants, including fruits and vegetables, and has strong anti-inflammatory effects, so it has received extensive attention as a potential anti-inflammatory antioxidant. However, the underlying basis of quercetin on inflammatory reactions and oxidative tension generated by lipopolysaccharide (LPS) in bovine intestinal epithelial cells (BIECs) is currently unexplained. This research aimed to determine the influence of quercetin on LPS-induced inflammatory reactions, oxidative tension, and the barrier role of BIECs. Our findings demonstrated that BIEC viability was significantly improved in LPS-treated BIEC with 80 μg/mL quercetin compared with the control group. Indicators of oxidative overload and genes involved in barrier role revealed that 80 μg/mL quercetin efficiently rescued BIECs from oxidative and barrier impairment triggered by 5 μg/mL LPS. In addition, the mRNA expression of pro-inflammatory cytokines TNF-α, IL-1β, and IL-6, as well as chemokines CXCL2, CXCL5, CCL5, and CXCL8, was diminished in LPS-treated BIECs with 80 μg/mL quercetin compared with LPS alone. Furthermore, the mRNA expression of toll-like receptor 4 (TLR4), CD14, myeloid differential protein-2 (MD2), and myeloid differentiation primary response protein (MyD88) genes associated with the TLR4 signal mechanism was markedly reduced by the addition of quercetin to LPS-modulated BIECs, indicating that quercetin can suppress the TLR4 signal mechanism. We performed Western blotting on the NF-κB signalling mechanism and compared it with immunofluorescence to further corroborate this conclusion. The LPS treatment enhanced the proportions of p-IκBα/GAPDH and p-p65/GAPDH. Compared with the LPS-treated group, quercetin administration decreased the proportions of p-IκBα/GAPDH and p-p65/GAPDH. In addition, immunofluorescence demonstrated that quercetin greatly reduced the LPS-induced nuclear translocation of NF-κB p65 in BIECs. The benefits of quercetin on inflammatory reactions in LPS-induced BIECs may be a result of its capacity to inhibit the TLR4-mediated NF-κB signalling mechanism. These findings suggest that quercetin can be used as an anti-inflammatory reagent to treat intestinal inflammation induced by LPS release.

Hepatitis C Virus Infection and Intrinsic Disorder in the Signaling Pathways Induced by Toll-Like Receptors

In this study, we examined the interplay between protein intrinsic disorder, hepatitis C virus (HCV) infection, and signaling pathways induced by Toll-like receptors (TLRs). To this end, 10 HCV proteins, 10 human TLRs, and 41 proteins from the TLR-induced downstream pathways were considered from the prevalence of intrinsic disorder. Mapping of the intrinsic disorder to the HCV-TLR interactome and to the TLR-based pathways of human innate immune response to the HCV infection demonstrates that substantial levels of intrinsic disorder are characteristic for proteins involved in the regulation and execution of these innate immunity pathways and in HCV-TLR interaction. Disordered regions, being commonly enriched in sites of various posttranslational modifications, may play important functional roles by promoting protein-protein interactions and support the binding of the analyzed proteins to other partners such as nucleic acids. It seems that this system represents an important illustration of the role of intrinsic disorder in virus-host warfare.

Quercetin Alleviates Lipopolysaccharide-Induced Inflammatory Response in Bovine Mammary Epithelial Cells by Suppressing TLR4/NF-κB Signaling Pathway

Bovine mastitis is one of the most common clinical diseases in dairy cows, causing huge economic losses to the dairy industry. Quercetin is an important flavonoid existing in many food resources, which has attracted widespread attention as a potential anti-inflammatory and antioxidant. However, the molecular mechanism of quercetin on inflammatory responses and oxidative stress in bovine mammary epithelial cells (BMECs) induced by lipopolysaccharide (LPS) remains unknown. The objective of this study was to investigate the effects of quercetin on inflammation responses, oxidative stress, and barrier function of BMEC induced by LPS. Our results showed that BMEC viability was not affected by treatment with 50 and 100 μg/ml of quercetin and 1 μg/ml of LPS compared with control group. The results of oxidative stress indicators and related genes of barrier function indicated that 100 μg/ml of quercetin effectively protected the BMECs from damage of oxidative and barrier induced by 1 μg/ml of LPS. Moreover, the messenger RNA (mRNA) expressions of pro-inflammatory cytokines TNF-α, IL-1β, IL-6, and chemokines CXCL2, CXCL5, CCL5, and CXCL8 were markedly decreased in the LPS-treated bovine retinal endothelial cells (BRECs) with 100 μg/ml of quercetin relatively to LPS alone. More importantly, the mRNA expressions of toll-like receptor 4 (TLR4), CD14, myeloid differential protein-2 (MD2), and myeloid differentiation primary response protein (MyD88) genes involved in TLR4 signal pathway were significantly attenuated by the addition of quercetin in LPS-treated BMEC, suggesting that quercetin can inhibit the TLR4 signal pathway. In addition, immunocytofluorescence showed that quercetin significantly inhibited the nuclear translocation of NF-κB p65 in BMEC induced by LPS. Therefore, the protective effects of quercetin on inflammatory responses in LPS-induced BMEC may be due to its ability to suppress the TLR4-mediated NF-κB signaling pathway. These findings suggest that quercetin can be used as an anti-inflammatory reagent to treat mastitis induced by exogenous or endogenous LPS release.

Toll-Like Receptor 3 in Cardiovascular Diseases

Toll-like receptor 3 (TLR3) is an important member of the innate immune response receptor toll-like receptors (TLRs) family, which plays a vital role in regulating immune response, promoting the maturation and differentiation of immune cells, and participating in the response of pro-inflammatory factors. TLR3 is activated by pathogen-associated molecular patterns and damage-associated molecular patterns, which support the pathophysiology of many diseases related to inflammation. An increasing number of studies have confirmed that TLR3, as a crucial medium of innate immunity, participates in the occurrence and development of cardiovascular diseases (CVDs) by regulating the transcription and translation of various cytokines, thus affecting the structure and physiological function of resident cells in the cardiovascular system, including vascular endothelial cells, vascular smooth muscle cells, cardiomyocytes, fibroblasts and macrophages. The dysfunction and structural damage of vascular endothelial cells and proliferation of vascular smooth muscle cells are the key factors in the occurrence of vascular diseases such as pulmonary arterial hypertension, atherosclerosis, myocardial hypertrophy, myocardial infarction, ischaemia/reperfusion injury, and heart failure. Meanwhile, cardiomyocytes, fibroblasts, and macrophages are involved in the development of CVDs. Therefore, the purpose of this review was to explore the latest research published on TLR3 in CVDs and discuss current understanding of potential mechanisms by which TLR3 contributes to CVDs. Even though TLR3 is a developing area, it has strong treatment potential as an immunomodulator and deserves further study for clinical translation.

Comparative Analysis of Gene Expression Patterns for Oral Epithelial Cell Functions in Periodontitis

The structure and function of epithelial cells are critical for the construction and maintenance of intact epithelial surfaces throughout the body. Beyond the mechanical barrier functions, epithelial cells have been identified as active participants in providing warning signals to the host immune and inflammatory cells and in communicating various detailed information on the noxious challenge to help drive specificity in the characteristics of the host response related to health or pathologic inflammation. Rhesus monkeys were used in these studies to evaluate the gingival transcriptome for naturally occurring disease samples (GeneChip® Rhesus Macaque Genome Array) or for ligature-induced disease (GeneChip® Rhesus Gene 1.0 ST Array) to explore up to 452 annotated genes related to epithelial cell structure and functions. Animals were distributed by age into four groups: ≤ 3 years (young), 3–7 years (adolescent), 12–16 years (adult), and 18–23 years (aged). For naturally occurring disease, adult and aged periodontitis animals were used, which comprised 34 animals (14 females and 20 males). Groups of nine animals in similar age groups were included in a ligature-induced periodontitis experiment. A buccal gingival sample from either healthy or periodontitis-affected tissues were collected, and microarray analysis performed. The overall results of this investigation suggested a substantial alteration in epithelial cell functions that occurs rapidly with disease initiation. Many of these changes were prolonged throughout disease progression and generally reflect a disruption of normal cellular functions that would presage the resulting tissue destruction and clinical disease measures. Finally, clinical resolution may not signify biological resolution and represent a continued risk for disease that may require considerations for additional biologically specific interventions to best manage further disease.

Dysfunctional monocytic toll-like receptor 4 signaling pathway and cognitive deficits in chronic schizophrenia patients with tardive dyskinesia

BACKGROUND

Mounting evidence suggests that the innate immune system is disrupted in schizophrenia patients with tardive dyskinesia (TD); however, the role of the toll-like receptor 4 (TLR4) signaling pathway remains unclear METHODS: In this study, we quantified the expression of the monocytic TLR4 signaling pathway using flow cytometry, before and after lipopolysaccharide (LPS) stimulation, in chronic schizophrenia patients with (n=61) and without TD (NTD, n=61) and healthy controls (HCs, n=74). Psychopathological symptoms, the severity of TD, and cognitive function were assessed using the Positive and Negative Syndrome Scale (PANSS), Abnormal Involuntary Movement Scale (AIMS), and MATRICS Consensus Cognitive Battery (MCCB), respectively RESULTS: 1) Both TD and NTD patients showed higher TLR4 signaling pathway activity at baseline than that in HCs, but their responses to LPS were weaker than those in HCs; 2) the alteration of the TLR4 signaling pathway was less severe in TD patients than in NTD patients; 3) TLR4 levels and MCCB scores were negatively correlated at baseline but positively correlated after LPS stimulation in TD patients; 4) there was no correlation between the TLR4 signals and PANSS or AIMS scores.

CONCLUSIONS

Our findings suggested the TLR4 signaling pathway disturbance might be related to cognitive deficits in schizophrenia patients with TD.

Autophagy receptor CCDC50 tunes the STING-mediated interferon response in viral infections and autoimmune diseases

DNA sensing and timely activation of interferon (IFN)-mediated innate immunity are crucial for the defense against DNA virus infections and the clearance of abnormal cells. However, overactivation of immune responses may lead to tissue damage and autoimmune diseases; therefore, these processes must be intricately regulated. STING is the key adaptor protein, which is activated by cyclic GMP-AMP, the second messenger derived from cGAS-mediated DNA sensing. Here, we report that CCDC50, a newly identified autophagy receptor, tunes STING-directed type I IFN signaling activity by delivering K63-polyubiquitinated STING to autolysosomes for degradation. Knockout of CCDC50 significantly increases herpes simplex virus 1 (HSV-1)- or DNA ligand-induced production of type I IFN and proinflammatory cytokines. Ccdc50-deficient mice show increased production of IFN, decreased viral replication, reduced cell infiltration, and improved survival rates compared with their wild-type littermates when challenged with HSV-1. Remarkably, the expression of CCDC50 is downregulated in systemic lupus erythematosus (SLE), a chronic autoimmune disease. CCDC50 levels are negatively correlated with IFN signaling pathway activation and disease severity in human SLE patients. CCDC50 deficiency potentiates the cGAS-STING-mediated immune response triggered by SLE serum. Thus, our findings reveal the critical role of CCDC50 in the immune regulation of viral infections and autoimmune diseases and provide insights into the therapeutic implications of CCDC50 manipulation.

Engineering Therapeutic Strategies in Cancer Immunotherapy via Exogenous Delivery of Toll-like Receptor Agonists

As a currently spotlighted method for cancer treatment, cancer immunotherapy has made a lot of progress in recent years. Among tremendous cancer immunotherapy boosters available nowadays, Toll-like receptor (TLR) agonists were specifically selected, because of their effective activation of innate and adaptive immune cells, such as dendritic cells (DCs), T cells, and macrophages. TLR agonists can activate signaling pathways of DCs to express CD80 and CD86 molecules, and secrete various cytokines and chemokines. The maturation of DCs stimulates naïve T cells to differentiate into functional cells, and induces B cell activation. Although TLR agonists have anti-tumor ability by activating the immune system of the host, their drawbacks, which include poor efficiency and remarkably short retention time in the body, must be overcome. In this review, we classify and summarize the recently reported delivery strategies using (1) exogenous TLR agonists to maintain the biological and physiological signaling activities of cargo agonists, (2) usage of multiple TLR agonists for synergistic immune responses, and (3) co-delivery using the combination with other immunomodulators or stimulants. In contrast to naked TLR agonists, these exogenous TLR delivery strategies successfully facilitated immune responses and subsequently mediated anti-tumor efficacy.

Bioinformatics Analysis of circRNA Expression and Construction of "circRNA-miRNA-mRNA" Competing Endogenous RNAs Networks in Bipolar Disorder Patients

Bipolar disorder (BD) is a severe mood disorder disease in China, and its underlying pathogenesis remains unknown. Circular RNAs (circRNAs) have been reported to play a key role in mental disorders and can be used as competitive endogenous RNAs (ceRNAs). However, little is known about the correlation of circRNAs with BD. In this study, Deep RNA sequencing was used to identify differentially expressed circRNAs (DE-circRNAs) and differentially expressed mRNAs (DE-mRNAs) between BD patients and a control group. Real-time quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was used to validate the differentially expressed RNAs (DE-RNAs). In all 9,593 circRNAs and 20,030 mRNAs were found in the two groups of specimens, among which 50 DE-circRNAs and 244 DE-mRNAs were significantly upregulated, and 44 DE-circRNAs and 294 DE-mRNAs were significantly downregulated. Based on the regulatory mechanism of ceRNAs, circRNAs can directly bind microRNAs (miRNAs) to affect mRNA expression, and the expression trends of circRNAs and mRNAs are consistent. According to this mechanism, we constructed two ceRNA networks by using the RNA sequencing data. The function of these DE-circRNAs was further elucidated by enrichment analysis. In summary, the present study showed that the circRNA expression profile of BD patients is altered, and a ceRNA regulatory network was constructed, which provided a hypothesis about the pathogenesis of BD.

Novel Biomimetic Human TLR2-Derived Peptides for Potential Targeting of Lipoteichoic Acid: An In Silico Assessment

Antimicrobial resistance is one of the most significant threats to health and economy around the globe and has been compounded by the emergence of COVID-19, raising important consequences for antimicrobial resistance development. Contrary to conventional targeting approaches, the use of biomimetic application via nanoparticles for enhanced cellular targeting, cell penetration and localized antibiotic delivery has been highlighted as a superior approach to identify novel targeting ligands for combatting antimicrobial resistance. Gram-positive bacterial cell walls contain lipoteichoic acid (LTA), which binds specifically to Toll-like receptor 2 (TLR2) on human macrophages. This phenomenon has the potential to be exploited for the design of biomimetic peptides for antibacterial application. In this study, we have derived peptides from sequences present in human TLR2 that bind to LTA with high affinity. In silico approaches including molecular modelling, molecular docking, molecular dynamics, and thermodynamics have enabled the identification of these crucial binding amino acids, the design of four novel biomimetic TLR2-derived peptides and their LTA binding potential. The outcomes of this study have revealed that one of these novel peptides binds to LTA more strongly and stably than the other three peptides and has the potential to enhance LTA targeting and bacterial cell penetration.

Effect of Tea Tree Oil on the Expression of Genes Involved in the Innate Immune System in Goat Rumen Epithelial Cells

Simple Summary

Subacute rumen acidosis (SARA) often causes significant losses on commercial farms. SARA is mainly caused by endotoxin (LPS) produced by the lysis of Gram-negative bacteria, which causes an inflammatory response. To alleviate the inflammatory response mediated by LPS, it is important to improve animal production performance. Tea tree oil (TTO) is a plant extract that possesses good bactericidal and anti-inflammatory effects. According to this study, LPS can significantly induce inflammatory responses in goat rumen epithelial cells (GRECs), while the addition of TTO could markedly mitigate inflammatory responses mediated by LPS in GRECs. Therefore, it may be useful for the treatment of SARA.

Abstract

In subacute rumen acidosis (SARA), the rumen epithelium is frequently attacked by endotoxin (LPS), which is caused by the lysis of dead Gram-negative bacteria. However, the rumen epithelium innate immune system can actively respond to the infection. Previous studies have demonstrated that tea tree oil (TTO) has good bactericidal and anti-inflammatory effects. Therefore, the aim of this study was to investigate the effect of TTO on the expression of genes involved in the inflammatory cytokines in goat rumen epithelial cells (GRECs) triggered by LPS. Our study shows that rumen epithelial cells isolated from goat rumen tissue can be cultured in vitro in 0.25% trypsin for a long time. These cells were identified as epithelial cells by the expression of cytokeratin 18, monocarboxylate transporter 4 (MCT4), Na[+]/H[+] hydrogen exchanger 1 (NHE1), putative anion transporter 1 (PAT1), vH⁺ ATPase B subunit (vH⁺ ATPase), and anion exchanger 2 (AE2). The mRNA expression of IL-1β, IL-6, TNF-α, TLR-2, NF-κB, CXCL6 and CXCL8 genes was significantly increased when LPS was used compared to untreated controls. In addition, mRNA expression of IL-1β, IL-6, TNF-α, TLR-2, NF-κB, CXCL8, CXCL6 and interferon-induced protein with tetratricopeptide repeats 3 (IFIT3) genes was also significantly higher in the LPS group compared to the 0.05% TTO group. However, the expression of IL-1β, IL-6, TNF-α, TLR-2, CXCL6 and IFIT3 genes was significantly lower in the LPS and 0.05% TTO group compared to the 1 μg/mL LPS group. These results suggest that TTO can inhibit LPS-induced inflammatory cytokines expression in GRECs.

Porcine Epidemic Diarrhea Virus Membrane Protein Interacted with IRF7 to Inhibit Type I IFN Production during Viral Infection

Porcine epidemic diarrhea virus (PEDV) is a highly pathogenic porcine enteropathogenic coronavirus causing severe enteritis and lethal watery diarrhea in piglets. PEDV infection suppresses the synthesis of type I IFN, and multiple viral proteins of PEDV have been shown to target the adaptors of innate immune pathways to inhibit type I IFN production. In this study, we identified PEDV membrane (M) protein as a new antagonist of type I IFN production in both human embryonic kidney HEK293T cells and porcine kidney PK-15 cells and determined the antagonistic mechanism used by M protein to target IFN regulatory factor 7 (IRF7), an important regulator of type I IFN production. IRF7 is phosphorylated and activated by TBK1 and IKKε in response to viral infection. We found that PEDV M protein interacted with the inhibitory domain of IRF7 and significantly suppressed TBK1/IKKε-induced IRF7 phosphorylation and dimerization of IRF7, leading to the decreased expression of type I IFN, although it did not affect the interaction between TBK1/IKKε and IRF7. As expected, overexpression of M protein significantly increased PEDV replication in porcine cells. The M proteins of both epidemic PEDV strains and vaccine strain showed similar antagonistic effect on type I IFN production, and the 1-55 region of M protein was essential for disruption of IRF7 function by interacting with IRF7. Taken together, our data identified a new, to our knowledge, IFN antagonist of PEDV, as well as a novel, to our knowledge, antagonistic mechanism evolved by PEDV to inhibit type I IFN production.

TLR7 Ligation Inhibits TLR8 Responsiveness in IL-27-Primed Human THP-1 Monocytes and Macrophages

Regulation of proinflammatory cytokine expression is critical in the face of single-stranded RNA (ssRNA) virus infections. Many viruses, including coronavirus and influenza virus, wreak havoc on the control of cytokine expression, leading to the formation of detrimental cytokine storms. Understanding the regulation and interplay between inflammatory cytokines is critical to the identification of targets involved in controlling the induction of cytokine expression. In this study, we focused on how the antiviral cytokine interleukin-27 (IL-27) regulates signal transduction downstream of Toll-like receptor 7 (TLR7) and TLR8 ligation, which recognize endosomal single-stranded RNA. Given that IL-27 alters bacterial-sensing TLR expression on myeloid cells and can inhibit replication of single-stranded RNA viruses, we investigated whether IL-27 affects expression and function of TLR7 and TLR8. Analysis of IL-27-treated THP-1 monocytic cells and THP-1-derived macrophages revealed changes in mRNA and protein expression of TLR7 and TLR8. Although treatment with IL-27 enhanced TLR7 expression, only TLR8-mediated cytokine secretion was amplified. Furthermore, we demonstrated that imiquimod, a TLR7 agonist, inhibited cytokine and chemokine production induced by a TLR8 agonist, TL8-506. Delineating the immunomodulatory role of IL-27 on TLR7 and TLR8 responses provides insight into how myeloid cell TLR-mediated responses are regulated during virus infection.

Size matters: TLR4-mediated effects of α-(1,5)-linear arabino-oligosaccharides in macrophage-like cells depend on their degree of polymerization

Linear arabino-oligosaccharides (LAOS) produced from controlled enzymatic hydrolysis of arabinans from sugar beet are well-known because of their chain-length dependent prebiotic effects. However, it is not clear if these α-(1,5)-linked arabinose oligosaccharides can interact directly with immune system cells, as well as if its degree of polymerization (DP) influences possible biological effects. Four high purity LAOS with distinct DP were tested in macrophage-like cells exposed or not to LPS. Results shown that LAOS interact with Toll-like receptor (TLR) 4 in a chain length-dependent manner. LAOS with higher DP induce stimulatory effects mainly through the TLR4/MyD88 pathway, thereby enhancing the release of tumor necrosis factor alpha (TNF-α), interleukin (IL-) 1β, 6, 12, and chemokines including MCP-1, RANTES, IL-8, and IP-10. Notably, LAOS with lower DP appears to have an opposite effect to those counterparts with higher DP, as they does not induce the secretion of cytokines and chemokines in macrophages-like cells, while also inhibit TLR4-mediated effects induced by both lipopolysaccharide and LAOS with higher DP. These findings provide not only insights into potential biological effects of LAOS, but also reveal that controlled enzymatic hydrolysis of sugar beet arabinans may lead to dietary oligosaccharides with desired biological properties.

Sox4 represses host innate immunity to facilitate pathogen infection by hijacking the TLR signaling networks

Toll-like receptors (TLRs) are essential for the protection of the host from pathogen infections by initiating the integration of contextual cues to regulate inflammation and immunity. However, without tightly controlled immune responses, the host will be subjected to detrimental outcomes. Therefore, it is important to balance the positive and negative regulations of TLRs to eliminate pathogen infection, yet avert harmful immunological consequences. This study revealed a distinct mechanism underlying the regulation of the TLR network. The expression of sex-determining region Y-box 4 (Sox4) is induced by virus infection in viral infected patients and cultured cells, which subsequently represses the TLR signaling network to facilitate viral replication at multiple levels by a distinct mechanism. Briefly, Sox4 inhibits the production of myeloid differentiation primary response gene 88 (MyD88) and most of the TLRs by binding to their promoters to attenuate gene transcription. In addition, Sox4 blocks the activities of the TLR/MyD88/IRAK4/TAK1 and TLR/TRIF/TRAF3/TBK1 pathways by repressing their key components. Moreover, Sox4 represses the activation of the nuclear factor kappa-B (NF-κB) through interacting with IKKα/α, and attenuates NF-kB and IFN regulatory factors 3/7 (IRF3/7) abundances by promoting protein degradation. All these contributed to the down-regulation of interferons (IFNs) and IFN-stimulated gene (ISG) expression, leading to facilitate the viral replications. Therefore, we reveal a distinct mechanism by which viral pathogens evade host innate immunity and discover a key regulator in host defense.

The Impact of Whole Sesame Seeds on the Expression of Key-Genes Involved in the Innate Immunity of Dairy Goats

Whole sesame seeds (WSS) are rich in both linoleic acid (LA) and lignans. However, their impact on the innate immunity of goats is not well studied. Twenty-four goats were divided into three homogeneous sub-groups; comprise one control (CON) and two treated (WWS5 and WWS10). In the treated groups, WSS were incorporated in the concentrates of the CON at 5 (WSS5) and 10% (WSS10) respectively, by partial substitution of both soybean meal and corn grain. The expression levels of MAPK1, IL6, TRIF, IFNG, TRAF3, and JUND genes in the neutrophils of WSS10 fed goats were reduced significantly compared with the CON. The same was found for the expression levels of IFNG and TRAF3 genes in the neutrophils of WSS5 fed goats. Both treated groups primarily affected the MYD88-independent pathway. The dietary supplementation of goats with WSS might be a good nutritional strategy to improve their innate immunity.

Role of Tristetraprolin in the Resolution of Inflammation

Simple Summary

Chronic inflammatory diseases account for up to 60% of deaths worldwide and, thus, are considered a great threat for human health by the World Health Organization. Nevertheless, acute inflammatory reactions are an integral part of the host defense against invading pathogens or injuries. To avoid excessive damage due to the persistence of a highly reactive environment, inflammations need to resolve in a coordinate and timely manner, ensuring for the immunological normalization of the affected tissues. Since post-transcriptional regulatory mechanisms are essential for effective resolution, the present review discusses the key role of the RNA-binding and post-transcriptional regulatory protein tristetraprolin in establishing resolution of inflammation.

Abstract

Inflammation is a crucial part of immune responses towards invading pathogens or tissue damage. While inflammatory reactions are aimed at removing the triggering stimulus, it is important that these processes are terminated in a coordinate manner to prevent excessive tissue damage due to the highly reactive inflammatory environment. Initiation of inflammatory responses was proposed to be regulated predominantly at a transcriptional level, whereas post-transcriptional modes of regulation appear to be crucial for resolution of inflammation. The RNA-binding protein tristetraprolin (TTP) interacts with AU-rich elements in the 3′ untranslated region of mRNAs, recruits deadenylase complexes and thereby facilitates degradation of its targets. As TTP regulates the mRNA stability of numerous inflammatory mediators, it was put forward as a crucial post-transcriptional regulator of inflammation. Here, we summarize the current understanding of the function of TTP with a specific focus on its role in adding to resolution of inflammation.

Roles of intestinal bacteroides in human health and diseases

Bacteroides, an abundant genus in the intestines of mammals, has been recently considered as the next generation probiotics (NGP) candidate due to its potential role in promoting host health. However, the role of Bacteroides in the development of intestinal dysfunctions such as diarrhea, inflammatory bowel disease, and colorectal cancer should not be overlooked. In the present study, we focused on nine most widely occurred and abundant Bacteroides species and discussed their roles in host immunity, glucose and lipid metabolism and the prevention or induction of diseases. Besides, we also discussed the current methods used in the safety evaluation of Bacteroides species and key opinions about the concerns of these strains for the future use.

The protective roles of tea tree oil extracts in bovine mammary epithelial cells and polymorphonuclear leukocytes

Background

Tea tree oil (TTO) plays an important role in antibacterial activity and alleviating the inflammatory responses. Bovine mammary epithelium and polymorphonuclear leukocytes (PMNL) can actively respond to bovine mastitis infection. However, regulatory effects of TTO extracts on the innate immune response of bovine mammary epithelial cells (BMECs) and PMNL remain not reported. Therefore, aim of the study was to evaluate the effects of TTO extracts on the mRNA levels of the genes involved in the innate immune response of BMECs and PMNL.

Results

Our results demonstrated that addition of 0.025% and 0.05% TTO increased the proliferation of BMECs, and significantly enhanced (P < 0.05) the viability of BMECs exposed to Staphylococcus aureus (S. aureus). An inhibitory effect was observed against the growth of S. aureus by TTO incubation. The 0.05% TTO reduced S. aureus biofilm formation, association and invasion of S. aureus to BMECs, and changed the morphological and structural features of S. aureus. The proinflammatory cytokines IL-1β, IL-6, and TNF-α were decreased (P < 0.001) by the incubation of TTO. Interestingly, the expression of IL-8 known for PMNL chemotactic function was elevated (P < 0.05) by 0.05% TTO treatment. Consistently, 0.05% TTO increased the migration of PMNL in S. aureus-exposed BMECs when compared with S. aureus treatment alone (P < 0.05). In addition, PMNL incubated with 0.05% TTO decreased the levels of NFKB inhibitor alpha (NFKBIA) and TNF-α.

Conclusions

Our results indicate that use of TTO can relieve the BMECs pro-inflammatory response caused by S. aureus and promote the migration of PMNL to mount the innate immune responses, and it may be novel strategy for the treatment of bovine mastitis caused by S. aureus.

The impact of rumen-protected amino acids on the expression of key- genes involved in the innate immunity of dairy sheep

Rumen protected amino acids inclusion in ewes’ diets has been proposed to enhance their innate immunity. The objective of this work was to determine the impact of dietary supplementation with rumen-protected methionine or lysine, as well as with a combination of these amino acids in two different ratios, on the expression of selected key-genes (NLRs, MyD88, TRIF, MAPK-1, IRF-3, JunD, TRAF-3, IRF-5, IL-1α, IL-10, IKK-α, STAT-3 and HO-1). Thus, sixty Chios dairy ewes (Ovis aries) were assigned to one of the following five dietary treatments (12 animals/ treatment): A: basal diet consist of concentrates, wheat straw and alfalfa hay (control group); B: basal diet +6.0 g/head rumen-protected methionine; C: basal diet + 5.0 g/head rumen-protected lysine; D: basal diet +6.0 g/head rumen-protected methionine + 5.0 g/head rumen-protected lysine and E: basal diet +12.0 g/head rumen-protected methionine + 5.0 g/head rumen-protected lysine. The results revealed a significant downregulation of relative transcript level of the IL-1α gene in the neutrophils of C and in monocytes of D ewes compared with the control. Significantly lower mRNA transcript accumulation was also observed for the MyD88 gene in the neutrophils of ewes fed with lysine only (C). The mRNA relative expression levels of JunD gene were highly induced in the monocytes, while those of IL-10 and HO-1 genes were declined in the neutrophils of ewes fed with the C and D diets compared with the control. Lower transcript levels of STAT-3 gene were observed in the neutrophils of ewes fed with either C or with E diets in comparison with the control. In conclusion, our results suggest that the dietary supplementation of ewes with rumen-protected amino acids, down regulate the expression of some genes involved in the pro-inflammatory signalling.

MHC class I and II peptide homology regulates the cellular immune response

Mammalian immune responses are initiated by "danger" signals--immutable molecular structures known as PAMPs. When detected by fixed, germline encoded receptors, pathogen-associated molecular pattern (PAMPs) subsequently inform the polarization of downstream adaptive responses depending upon identity and localization of the PAMP. Here, we report the existence of a completely novel "PAMP" that is not a molecular structure but an antigenic pattern. This pattern--the incidence of peptide epitopes with stretches of 100% sequence identity bound to both dendritic cell (DC) major histocompatibility (MHC) class I and MHC class II--strongly induces T_H 1 immune polarization and activation of the cellular immune response. Inherent in the existence of this PAMP is the concomitant existence of a molecular sensor complex with the ability to scan and compare amino acid sequence identities of bound class I and II peptides. We provide substantial evidence implicating the multienzyme aminoacyl-tRNA synthetase (mARS) complex and its AIMp1 structural component as the key constituents of this complex. The results demonstrate a wholly novel mechanism by which T-helper (T_H ) polarization is governed and provide critical information for the design of vaccination strategies intended to provoke cell-mediated immunity.

The discovery of potent immunostimulatory CpG-ODNs widely distributed in bacterial genomes

Oligodeoxynucleotides containing unmethylated CpG dinucleotides (CpG-ODN) can be specifically recognized by Toll-like receptor 9 (TLR9), provoking innate immune responses. Designed according to this structural feature, many synthetic phosphorothioate CpG-ODNs successfully activate macrophages. However, it is difficult to find potent stimulatory CpG-DNA fragments in microbial genomes. Therefore, whether microbial CpG-DNA substantially contributes to infectious and immune diseases remains controversial. In this study, high-throughput scanning was carried out for thousands of bacterial genomes with bioinformatics tools to comprehensively evaluate the distribution of CpG-DNA fragments. A random sampling test was then performed to verify their immunostimulatory properties by experiments in vitro and in vivo. Natural TLR9-dependent and potent stimulatory CpG-DNA fragments were found in microbial genomes. Interestingly, highly conserved stimulatory CpG-DNA fragments were found in 16S and 23S rDNA sequences with multiple copies, while others were species-specific. Additionally, we found that the reported active motifs were mostly non-stimulatory in natural CpG fragments. This evidence indicates that the previous structural descriptions of functional CpG-ODNs are incomplete. Our study has assessed the distribution of microbial CpG-DNA fragments, and identified natural stimulatory CpG-DNA fragments. These findings provide a deeper understanding of CpG-ODN structures and new evidence for microbial DNA inflammatory function and pathogenicity.

Toll-Like Receptors-2 and -4 in Graves' Disease-Key Players or Bystanders?

Graves’ disease (GD) is an autoimmune disease that affects the thyroid. The development of autoimmunity is associated with innate immune responses where the prominent role plays Toll-like receptors (TLRs). The aim of our study was to assess the relationship between the expression levels of TLR-2 and TLR-4 on CD4+ and CD8+ T as well as CD19+ B lymphocytes in patients with GD and selected clinical parameters. The study group consisted of 32 women with GD, the control group consisted of 20 healthy women. Immunophenotyping was performed using the flow cytometry and cytokines concentrations were assessed using ELISA assay. The mean percentage of CD4+/TLR-2+ and CD8+/TLR-2+ T cells in patients with GD was higher than in the control group (p < 0.0001). After obtaining euthyroidism, the mean percentage of CD4+/TLR-2+ T cells in patients with GD decreased (p < 0.0001). The expression level of TLR-2 on CD4+ T lymphocytes correlated with serum FT3 concentration in patients with GD (r = 0.47, p = 0.007). The mean percentage of CD8+/TLR-2+ T cells in patients with GD before treatment compared to patients with GD after obtaining euthyroidism was higher (p = 0.0163). Similar findings were found for TLR-4. Thus the TLR-2 and TLR-4 can be a prognostic marker for Graves’ disease.

Acute neuroinflammation elicited by TLR-3 systemic activation combined with early life stress induces working memory impairments in male adolescent mice

Toll-like Receptors (TLRs) are implicated with the pathogenesis of cognitive impairment induced by inflammation. Early life stress is associated with altered trajectories of neuroimmune signaling with implications for cognitive development. However, effects of TLR-3 activation on early life stress-related cognitive outcomes are understudied. We investigated the effects of maternal separation (MS) during postnatal development and a viral immune challenge during adolescence on working memory performance. BALB/c mice exposed to MS were separated from their dams daily for 180-min from postnatal day (PND) 2 to 15. At PND 45, animals were challenged with a single i.p. injection of either Poly (I:C) or sterile saline, and then subjected to a spatial working memory test in a Y-maze apparatus. Gene expression was determined by qPCR. Protein levels of oxidative stress markers were also assessed. A single peripheral administration of a TLR-3 agonist was able to induce working memory impairments in adolescent mice exposed to MS. At a molecular level, exposure to MS was associated with lower mRNA levels of Tlr3 in the medial prefrontal cortex (mPFC). However, when MS animals were exposed to Poly (I:C), a more robust activation of Tlr3, Il6 and Nfkb1 gene transcription was observed in these mice compared with control animals. These modifications did not result in oxidative stress. Finally, higher mRNA levels of Nfkb1 in the mPFC were correlated with lower working memory performance, suggesting that altered NF-κB signaling might be related with poor cognitive functioning. These results have implications for how ELS affects neuroimmune signaling in the mPFC.

Essential roles of S100A10 in Toll-like receptor signaling and immunity to infection

Toll-like receptors (TLRs) are key pattern recognition receptors that mediate innate immune responses to infection. However, uncontrolled TLR activation can lead to severe inflammatory disorders such as septic shock. The molecular mechanisms through which TLR responses are regulated are not fully understood. Here, we demonstrate an essential function of S100A10 in TLR signaling. S100A10 was constitutively expressed in macrophages, but was significantly downregulated upon TLR activation. S100A10-deficient macrophages were hyperresponsive to TLR stimulation, and S100A10-deficient mice were more sensitive to endotoxin-induced lethal shock and Escherichia coli-induced abdominal sepsis. Mechanistically, S100A10 regulated macrophage inflammatory responses by interfering with the appropriate recruitment and activation of the receptor-proximal signaling components and eventually inhibited TLR-triggered downstream signaling. These findings expand our understanding of TLR signaling and establish S100A10 as an essential negative regulator of TLR function and a potential therapeutic target for treating inflammatory diseases.

The Interaction Between Two Worlds: MicroRNAs and Toll-Like Receptors

MicroRNAs (miRNAs) are critical mediators of posttranscriptional regulation via their targeting of the imperfect antisense complementary regions of coding and non-coding transcripts. Recently, researchers have shown that miRNAs play roles in many aspects of regulation of immune cell function by targeting of inflammation-associated genes, including Toll-like receptors (TLRs). Besides this indirect regulatory role of miRNAs, they can also act as physiological ligands of specific TLRs and initiate the signaling cascade of immune response. In this review, we summarize the potential roles of miRNAs in regulation of TLR gene expression and TLR signaling, with a focus on the ability of miRNAs bind to TLRs.

Inhibition of osteoclastogenesis by opsonized Porphyromonas gingivalis

A crucial step in the pathogenesis of periodontal disease (PD) is activation of osteoclasts (OC) by numerous virulence factors produced by Porphyromonas gingivalis (Pg). To understand pathogenesis of PD and the role of specific adaptive immune responses, effects of antibodies on Pg‐induced OC differentiation and function were investigated. Human peripheral blood‐derived monocytes were differentiated to OC in the presence or absence of: (a) Pg; (b) antibodies to Pg; and (c) antibody‐opsonized Pg. Findings suggest significant induction of osteoclastogenesis by Pg when compared to control cultures, whereas opsonization decreased osteoclastogenesis by 45%. Immune receptor gene expression profile in the presence of opsonized Pg showed marked upregulation of TLR1 (three‐fold) and TLR2 (twofold) along with FcγRIIB (two‐fold) and FcγRIII receptors (five‐fold), but not TLR4 and FcRγ receptors. Interestingly, blocking FcγRIIB, but not FcγRIII receptor, reversed the inhibitory effects of opsonized Pg suggesting a critical role played by FcγRIIB in osteoclastogenesis. Furthermore, opsonized Pg transformed OC precursors to a “macrophage phenotype” suggesting a bone protective role of the immune complexes in modulating osteoclastogenesis, probably by competing as an agonist for pattern recognition receptors, and inducing selective activation of FcγRs with simultaneous suppression of FcRγ which regulates bone resorptive process. Further defining effective antibody isotypes, avidity, and antigenic specificity could improve targets for eliciting protective immunity.