Members Of Toll-like Receptor Family Research Articles

TIR domains of TLR family-from the cell culture to the protein sample for structural studies.

Toll-like receptors (TLRs) are key players in the innate immune system. Despite the great efforts in TLR structural biology, today we know the spatial structures of only four human TLR intracellular TIR domains. All of them belong to one of five subfamilies of receptors. One of the main bottlenecks is the high-level production of correctly folded proteins in soluble form. Here we used a rational approach to find the optimal parameters to produce TIR domains of all ten human TLR family members in soluble form in E. coli cells. We showed that dozens of milligrams of soluble His-tagged TLR2/3/6/7TIR and MBP-tagged TLR3/5/7/8TIR can be produced. We also developed the purification protocols and demonstrated by CD and NMR spectroscopy that purified TLR2/3/7TIR demonstrate a structural organization inherent to TIR domains. This illustrates the correct folding of produced proteins and their suitability for further structural and functional investigations.

Toll-Like Receptors 7/8: A Paradigm for the Manipulation of Immunologic Reactions for Immunotherapy.

The innate immune system recognizes conserved features of viral and microbial pathogens through pattern recognition receptors (PRRs). Toll-like receptors (TLRs) are one type of PRR used by the innate immune system to mediate the secretion of proinflammatory cytokines and promote innate and adaptive immune responses. TLR family members TLR7 and TLR8 (referred to as TLR7/8 from herein) are endosomal transmembrane receptors that recognize purine-rich single-stranded RNA (ssRNA) and bacterial DNA, eliciting an immunologic reaction to pathogens. TLR7/8 were discovered to mediate the secretion of proinflammatory cytokines by activating immune cells. In addition, accumulating evidence has indicated that TLR7/8 may be closely related to numerous immune-mediated disorders, specifically several types of cancer, autoimmune disease, and viral disease. TLR7/8 agonists and antagonists, which are used as drugs or adjuvants, have been identified in preclinical studies and clinical trials as promising immune stimulators for the immunotherapy of these immune-mediated disorders. These results provided reasoning to further explore immunotherapy for the treatment of immune-mediated disorders. Nevertheless, numerous needs remain unmet, and the therapeutic effects of TLR7/8 agonists and antagonists are poor and exert strong immune-related toxicities. The present review aimed to provide an overview of the TLR family members, particularly TLR7/8, and address the underlying molecular mechanisms and clinical implications of TLR7/8 in immune-mediated disorders. The aim of the work is to discuss the underlying molecular mechanisms and clinical implications of TLR7/8 in immune-mediated disorders.

Surface immunogenic protein from Streptococcus agalactiae and Fissurella latimarginata hemocyanin are TLR4 ligands and activate MyD88- and TRIF dependent signaling pathways.

The development of vaccine adjuvants is of interest for the management of chronic diseases, cancer, and future pandemics. Therefore, the role of Toll-like receptors (TLRs) in the effects of vaccine adjuvants has been investigated. TLR4 ligand-based adjuvants are the most frequently used adjuvants for human vaccines. Among TLR family members, TLR4 has unique dual signaling capabilities due to the recruitment of two adapter proteins, myeloid differentiation marker 88 (MyD88) and interferon-β adapter inducer containing the toll-interleukin-1 receptor (TIR) domain (TRIF). MyD88-mediated signaling triggers a proinflammatory innate immune response, while TRIF-mediated signaling leads to an adaptive immune response. Most studies have used lipopolysaccharide-based ligands as TLR4 ligand-based adjuvants; however, although protein-based ligands have been proven advantageous as adjuvants, their mechanisms of action, including their ability to undergo structural modifications to achieve optimal immunogenicity, have been explored less thoroughly. In this work, we characterized the effects of two protein-based adjuvants (PBAs) on TLR4 signaling via the recruitment of MyD88 and TRIF. As models of TLR4-PBAs, we used hemocyanin from Fissurella latimarginata (FLH) and a recombinant surface immunogenic protein (rSIP) from Streptococcus agalactiae. We determined that rSIP and FLH are partial TLR4 agonists, and depending on the protein agonist used, TLR4 has a unique bias toward the TRIF or MyD88 pathway. Furthermore, when characterizing gene products with MyD88 and TRIF pathway-dependent expression, differences in TLR4-associated signaling were observed. rSIP and FLH require MyD88 and TRIF to activate nuclear factor kappa beta (NF-κB) and interferon regulatory factor (IRF). However, rSIP and FLH have a specific pattern of interleukin 6 (IL-6) and interferon gamma-induced protein 10 (IP-10) secretion associated with MyD88 and TRIF recruitment. Functionally, rSIP and FLH promote antigen cross-presentation in a manner dependent on TLR4, MyD88 and TRIF signaling. However, FLH activates a specific TRIF-dependent signaling pathway associated with cytokine expression and a pathway dependent on MyD88 and TRIF recruitment for antigen cross-presentation. Finally, this work supports the use of these TLR4-PBAs as clinically useful vaccine adjuvants that selectively activate TRIF- and MyD88-dependent signaling to drive safe innate immune responses and vigorous Th1 adaptive immune responses.

Identification of olive flounder (Paralichthys olivaceus) toll-like receptor genes: Involvement in immune response to temperature stress and Edwardsiella tarda infection.

Toll-like receptor (TLR) genes are best known for their roles in the innate immune defense. However, studies focusing on the reaction mechanisms of TLR genes in olive flounder (Paralichthys olivaceus) immune responses are still limited. In this study, 11 TLR family members (PoTLRs) were identified and classified from P. olivaceus genome. Phylogenetic analysis showed that PoTLRs were highly conserved in olive flounder. The analysis of motif prediction and gene structure indicated that TLRs had high sequence similarity. The expression patterns in developmental stages and different tissues showed that TLR members were spatially and temporally specific. RNA-Seq analysis of temperature stress and Edwardsiella tarda infection suggested that TLR members were involved in inflammatory responses, PoTLR5b and PoTLR22 showed significant differences in response to both temperature stress and E. tarda stress, indicating their potential immune functions. The results of this study suggested that TLR genes played important roles in the innate immune response of olive flounder, and would provide a solid basis for further study of their functions.

Genome-wide identification and expression analyses of Toll-like receptors provide new insights on adaptation to intertidal benthic environments in Urechis unicinctus (Annelida, Echiura)

Toll-like receptors (TLR) are an important class of pattern recognition receptors involved in innate immunity that recognize pathogen-associated and damage-associated molecular patterns. Although the role of TLRs in immunity has been extensively studied, a systematic investigation of their function in environmental adaptation is still in its infancy. In this study, a genome-wide search was conducted to systematically investigate TLR family members of Urechis unicinctus, a typical benthic organism in intertidal mudflats. A total of 28 TLR genes were identified in the U. unicinctus genome, and their fundamental physiological and biochemical properties were characterized. Gene copy number analysis among species in different habitats indicated that TLR family gene expansion may be probably related with benthic environmental adaptation. To further investigate the expression patterns of TLR members under environmental stress, transcriptome data was analyzed from different developmental stages and the hindgut under sulfide stress. Transcriptome analysis of different developmental stages showed that most TLR genes were highly expressed during a key period of benthic environment adaptation (worm-shaped larva). Transcriptome analysis of the hindgut under sulfide stress showed that the expression of 12 TLR members was significantly induced under sulfide stress. These results indicate that the regulation of TLR gene expression may be probably involved in the adaptation of U. unicinctus to the benthic intertidal zone environment. Taken together, this study may lay the foundation for future functional analysis of the specific role of TLRs in host immune responses against sulfide exposure and benthic environmental stress in annelid.

Cyclosporine Ameliorates Silica-Induced Autoimmune Hepatitis in Rat Model by Altering the Expression of Toll-Like Receptor-4, Interleukin-2, and Tumor Necrosis Factor-α.

Autoimmune hepatitis (AIH) is an inflammatory liver disease that is characterized histologically by interface hepatitis, biochemically by elevated transaminase levels, and serologically by the presence of autoantibodies. Toll-like receptor (TLR)-4 is a TLR family member that, upon activation in hepatocytes, initiates a cascade of events. Interleukin-2 (IL-2) and tumour necrosis factor α (TNF-α) are potent inflammatory cytokines secreted in AIH, playing an important role in the early development of inflammation and hepatocyte damage. This study examined the role of cyclosporine in AIH and illustrated its actions on altered hepatic function in the silica-induced AIH model. AIH was induced in Wistar rats using sodium silicate. The rats were divided into four groups: the control group, silica-AIH group, cyclosporine-treated group, and prevention group. TLR-4 and IL-2 mRNA expressions in liver tissues were tested by RTPCR. AIH was associated with up-regulation of liver enzymes, IL-2 and TLR-4 gene expression, while cyclosporine significantly down-regulated the expression of both. The relative quantity of TLR-4 mRNA was 1±0, 13.57±1.91, 4±0.38, and 2±0 in control, AIH, cyclosporine, and prevention groups, respectively (p<0.001). Also, the relative quantity of IL-2 mRNA was 1±0, 14.79±1.42, 7.07±0.96, and 3.4±0.55 in control, AIH, cyclosporine, and prevention groups, respectively (p<0.001). Additionally, immunohistochemical staining for TNF-α in liver sections was increased in the silica-AIH group but was found to decrease in the cyclosporine-treated and prevention groups. This study advocates the therapeutic role of cyclosporine in treating immune-mediated hepatic diseases. Cyclosporine improves histological alterations in the liver and inhibits the production of proinflammatory cytokines.

Expressions of Toll Like Receptor (TLR) Genes in Paralichthys olivaceus After Induced by Different Extracts of Edwardsiella tarda.

Toll like receptors (TLRs) are the main innate immune ‘pattern recognition receptors’ of animals, which play a central role in host cell recognition and responses to invasive pathogens, particularly common structures of microbial pathogens. In this study, the gene expression profiles of TLRs in the spleen, head kidney, gill, small intestine, liver, muscle, and heart of healthy Paralichthys olivaceus were detected by real-time quantitative PCR (qPCR). The TLR family members were widely expressed in different tissues with different basic expression profiles. The highest expressions of TLR1, 5m, 7, 8, 9, 14, and 21 were found in the spleen; the highest expressions of TLR3 and TLR21 were found in the gill; the highest expressions of TLR2 and 5s were found in the small intestine. The second highest expressions of TLR3, 7, and 8 were found in small intestine. The gene expression profiles of TLRs stimulated with Edwardsiella tarda DNA, RNA, and lipopolysaccharide (LPS) were also detected in spleen, head kidney and gill. TLR9 and TLR21 were sensitive to E. tarda DNA; TLR 8 and TLR21 were sensitive to E. tarda RNA; and TLR1 and TLR14 were sensitive to E. tarda LPS. The expressions of the other TLR genes showed no significant changes. The results imply that the expressions of these TLR genes in P. olivaceus are differently regulated in the whole body and play important roles in the immune response against E. tarda infection.

Fat body-derived Spz5 remotely facilitates tumor-suppressive cell competition through Toll-6-α-Spectrin axis-mediated Hippo activation.

Tumor-suppressive cell competition is an evolutionarily conserved process that selectively removes precancerous cells to maintain tissue homeostasis. Using the polarity-deficiency-induced cell competition model in Drosophila, we identify Toll-6, a Toll-like receptor family member, as a driver of tension-mediated cell competition through α-Spectrin (α-Spec)-Yorkie (Yki) cascade. Toll-6 aggregates along the boundary between wild-type and polarity-deficient clones, where Toll-6 physically interacts with the cytoskeleton network protein α-Spec to increase mechanical tension, resulting in actomyosin-dependent Hippo pathway activation and the elimination of scrib mutant cells. Furthermore, we show that Spz5 secreted from fat body, the key innate organ in fly, facilitates the elimination of scrib clones by binding to Toll-6. These findings uncover mechanisms by which fat bodies remotely regulate tumor-suppressive cell competition of polarity-deficient tumors through inter-organ crosstalk and identified the Toll-6-α-Spec axis as an essential guardian that prevents tumorigenesis via tension-mediated cell elimination.

Genome-wide characterization of the Toll-like receptor gene family in Triplophysa rosa and expression profiles in response to Aeromonas hydrophila infection

Toll-like receptors (TLRs) are key pattern recognition receptors playing a pivotal role in innate immunity against pathogen invasion. Although numerous studies have clarified the characteristics and functions of TLRs in both invertebrates and vertebrates, little information is available about TLR genes in the cavefish Triplophysa rosa. Hence, 16 TLR family members, including several fish-specific TLRs (TLR18, TLR19, TLR20, and TLR21), were identified and characterized based on the T. rosa genome. Phylogenetic analysis showed that these TLR genes could be classified into six subfamilies, namely TLR1, TLR3, TLR4, TLR5, TLR7, and TLR11, revealing their evolutionary conservation together with structural analysis. By examining gene copy numbers of TLR genes from several fish species, gene duplications and losses were observed. Moreover, the expression patterns of TLR genes in the gill, skin, intestine, and liver of healthy T. rosa, as well as those in the gill and intestine, in response to Aeromonas hydrophila infection, were investigated by qPCR. Results revealed that 16 TLR genes were ubiquitously expressed in all tested tissues. Furthermore, the expression of most TLRs, including TrTLR4.1, TrTLR4.2, TrTLR5.1, TrTLR9, TrTLR18, TrTLR19, and TrTLR20, was upregulated at all time points. Most TLRs in mucosal immune organs significantly responded to A. hydrophila infection, indicating that the differential expression of TLRs plays important roles in mediating innate immune responses for host defense. Collectively, our findings might help elucidate the crucial roles of TLRs in the immune response of T. rosa, providing valuable genomic resources for future studies investigating the innate immune mechanisms underlying host defense against pathogen infection.

Characterization of a novel toll-like receptor and activation NF-κB signal pathway in triangle sail mussel Hyriopsis cumingii.

Toll-like receptor (TLR) family plays an important role in innate immunity for detection of and defense against microbial pathogens. In this study, a novel toll-like receptor (HcTLRn) was characterized from freshwater pearl mussel H. cumingii. The complete sequence of HcTLRn was 3725 bp, and the open reading frame (ORF) encoded 718 amino acid residues. Predicted HcTLRn protein possessed seven atypical leucine-rich repeat (LRR) domains, two typical LRR subfamily domains, a C-terminal domain LRR, a transmembrane domain and an intracellular Toll/interleukin-1 (IL-1) receptor domain. Transcripts of HcTLRn were constitutive expressed in the tissues of healthy mussels and were markedly induced in hepatopancreas and gills after lipopolysaccharide (LPS), peptidoglycan (PGN) and polyinosinic polycytidylic acid (ploy I: C) stimulation. Knockdown of HcTLRn in vivo significantly decreased the mRNA levels of TLR pathway transcription factors p65 and p105 as well as antimicrobial peptides (AMPs) including lysozyme (HcLys), theromacin (HcTher), whey acidic protein (HcWAP), LPS-binding protein/bactericidal permeability increasing protein (HcLBP/BPI) 1 and 2 after mussels challenged by LPS. In situ hybridization results showed that HcTLRn mRNA was significantly increased in hemocytes after LPS, PGN and poly I:C stimulation. HcTLRn protein was mainly expressed in hepatopancreas and gills and was significantly increased after LPS stimulation. Moreover, recombinant extracellular domain of HcTLRn (HcTLRn-ECD) proteins could bind to a variety of bacterial and pathogen-associated molecular patterns such as LPS, PGN, and poly I:C in vitro. Subcellular localization results showed that HcTLRn was mainly distributed near the cell membrane and in cytoplasm. Over-expression of HcTLRn activated the NF-κB luciferase reporter in HEK293T cells. Collectively, these results suggested that HcTLRn was a TLR family member that might play an important role in activation of NF-κB signal pathway in Mollusca.

Genome-wide identification, characterization, and expression of the Toll-like receptors in Japanese flounder (Paralichthys olivaceus)

Toll-like receptor (TLR) family is a key ancient component of pattern recognition receptors, conserved from insects to mammals, which plays significant roles in immune defense against pathogens invasion. Teleost-specific TLR family members have lost some of the mammalian TLR orthologues or produced duplicates, particularly all bacterial could recognize cell surface TLRs. Edwardsiella tarda is an important pathogen of Japanese flounder (Paralichthys olivaceus) resulting in great economic losses. However, there is little integrated information of the roles about TLRs in mediating immune response to E.tarda infection in Japanese flounder. Here, we performed data-mining on the P. olivaceus genome to extract eleven TLR members: TLR1, TLR2, TLR3, TLR5M, TLR5S, TLR7, TLR8, TLR9, TLR18, TLR21 and TLR22. The TLR family motifs, such as Toll/interleukin (IL)-1 receptor (TIR) domain and leucine rich repeat (LRR) are conserved in TLR1-3, 5M, 7-9, 18, 21 and 22. Phylogenetic analysis verified their identities and supported the classification of TLRs into six subfamilies as in other vertebrates. And then, the expression of P. olivaceus TLRs (PoTLRs) were widely detected in immune-related tissues including intestine, skin, spleen, kidney, liver, and gill. Subsequently, the PoTLRs were exhibited differential regulation in immune-related tissues, such as intestine, spleen, liver and kidney following bacterial challenge by infection with E.tarda, indicating their roles in the immune response. The syntenic analysis showed neighboring genes of TLR1, 7, 8 and 18 were relatively conserved among P.olivaceus, O.latipes, and C.semilaevis. Meanwhile, protein and protein interaction network (PPI) results explained that TLR genes interacted with immune-related mediating factors including Interleukin-related genes, e.g. Il1 and Il10, MyD88-dependent pathway, Sarm1 and NF-κB signaling pathway, which could bind to TIR domain. These analyses will contribute to the functional characterization of P. olivaceus TLRs in further study.

Efficacy of SPG-ODN 1826 Nanovehicles in Inducing M1 Phenotype through TLR-9 Activation in Murine Alveolar J774A.1 Cells: Plausible Nano-Immunotherapy for Lung Carcinoma.

Alveolar macrophages are the first line of defense against intruding pathogens and play a critical role in cancer immunology. The Toll-like receptor (TLR) family mediates an important role in recognizing and mounting an immune response against intruding microbes. TLR-9 is a member of the intracellular TLR family, which recognizes unmethylated CG motifs from the prokaryotic genome. Upon its activation, TLR-9 triggers downstream of the MyD-88-dependent transcriptional activation of NF-κB, and subsequently results in abundant inflammatory cytokines expression that induces a profound inflammatory milieu. The present exploratory investigation aimed at elucidating the potency of schizophyllan for entrapping ODN 1826 (SPG-ODN 1826)-mediated stimulation of TLR-9 in provoking an inflammatory-type response in murine alveolar macrophages. Schizophyllan (SPG), a representative of the β-glucan family, was used in the present study as a nanovehicle for endosomal trafficking of CpG ODN 1826. TEM analysis of SPG-ODN 1826 nanovehicles revealed that the prepared nanovehicles are spherical and have an average size of about 100 nm. Interestingly, SPG-ODN 1826 nanovehicles were competent in delivering their therapeutic payload within endosomes of murine alveolar macrophage (J774A.1) cells. Exposure of these nanovehicles within LPS stimulated J774A.1, resulted in a significant provocation of reactive oxygen species (ROS) (p < 0.01) in comparison to CpG ODN 1826 alone. Moreover, the formulated nanovehicles succeeded in generating a profound Th1-based cytokine profile constituted by enhanced expression of IFN-γ (p < 0.001) and IL-1β (p < 0.001) inflammatory cytokines. These findings clearly indicated the immunostimulatory potential of SPG-ODN 1826 nanovehicles for inducing the Th1-type phenotype, which would certainly assist in skewing M2 phenotype into the much-desired M1 type during lung cancer.

Role of necroptosis in infection-related, immune-mediated, and autoimmune skin diseases.

Regulated necrosis, also termed necroptosis, is another programmed cell death depending on a unique molecular pathway that does not overlap with apoptosis. Tumor necrosis factor and Toll-like receptor family members, interferon, and other mediators are the factors that mainly cause necroptosis. Activating necroptosis by ligands of death receptors requires the kinase activity of receptor-interacting proteins 1 and 3, and a mixed lineage kinase domain-like protein, which is a critical downstream mediator of necroptosis. Increasing evidence has revealed that necroptosis does not only involve physiological regulation but also the occurrence, development, and prognosis of certain diseases, such as septicemia, neurodegenerative diseases, and ischemic-reperfusion injury. Many excellent documented systematic discussions of necroptosis and its role in various skin diseases. In this review, we summarize the molecular mechanism of necroptosis, as well as the current knowledge on the contribution of necroptosis, in infection-related, immune-mediated, autoimmune skin diseases, and malignant skin tumors.

TLR10 and Its Role in Immunity.

Toll like receptors (TLRs) are the most studied pattern recognition receptors (PRRs) as they connect the innate to the acquired immune response. To date, there are ten human TLRs which are expressed either on the plasma membrane or on the endosomes. TLR1, TLR2, TLR4, TLR5, TLR6 and TLR10 are plasma membrane TLRs that recognise extracellular components of pathogens, whereas TLR3, TLR7, TLR8 and TLR9 are located on endosomes where they recognise foreign nucleic acids. Of these TLRs, TLR10 is the latest human TLR to be discovered and its function and ligands are still unclear. TLR10 is the only known member of TLR family that can elicit anti-inflammatory effect. TLR10 can inhibit other TLRs by competing with stimulatory TLRs, dimerising with TLR1, TLR2 and TLR6, and by inducing PI3K/Akt to produce IL-1Ra. There is controversy on the function of TLR10 as an anti-inflammatory TLR as initial studies on TLR10 revealed it to promote inflammation. Herein, we review the detailed functions of TLR10 in immunity and give an account of how and when TLR10 can act on both sides of the inflammatory spectrum.

Discovery of Potent and Orally Bioavailable Small Molecule Antagonists of Toll-like Receptors 7/8/9 (TLR7/8/9).

The toll-like receptor (TLR) family is an evolutionarily conserved component of the innate immune system, responsible for the early detection of foreign or endogenous threat signals. In the context of autoimmunity, the unintended recognition of self-motifs as foreign promotes initiation or propagation of disease. Overactivation of TLR7 and TLR9 have been implicated as factors contributing to autoimmune disorders such as psoriasis, arthritis, and lupus. In our search for small molecule antagonists of TLR7/9, 7f was identified as possessing excellent on-target potency for human TLR7/9 as well as for TLR8, with selectivity against other representative TLR family members. Good pharmacokinetic properties and a relatively balanced potency against TLR7 and TLR9 in mouse systems (systems which lack functional TLR8) made this an excellent in vivo tool compound, and efficacy from oral dosing in preclinical models of autoimmune disease was demonstrated.

Small-Molecule Modulators of Toll-like Receptors.

Toll-like receptors (TLRs) are the "gatekeepers" of the immune system in humans and other animals to protect the host from invading bacteria, viruses, and other microorganisms. Since TLR4 was discovered as the receptor for endotoxin in the late 1990s, significant progress has been made in exploiting an understanding of the function of TLRs. The TLR-signaling pathway is crucial for the induction and progression of various diseases. Dysregulation of TLR signaling contributes to numerous pathological conditions, including chronic inflammation, sepsis, cancers, asthma, neuropathic pain, drug addiction, and autoimmune diseases. Therefore, manipulation of TLR signaling is promising to halt their activity in inflammatory diseases, to enhance their signaling to fight cancers, to modulate their role in autoimmune diseases, and to suppress them to treat drug addiction. TLR agonists have demonstrated great potential as antimicrobial agents and vaccine adjuvants, whereas TLR antagonists are being developed as reagents and drugs to dampen immune responses. Because of their pivotal potential therapeutic applications, fruitful small-molecule compounds and peptide fragments have been discovered, and many of them have advanced to various stages of clinical trials (though only two have been approved by the Food and Drug Administration (FDA): MPLA as a TLR4 agonist and imiquimod as a TLR7 agonist).In this Account, we focus on the progress in developing TLR signaling pathway modulators (mainly focused on the Yin and Wang laboratories) over the past decade and highlight the accomplishments and currently existing challenges in the development of TLR modulators. First, we briefly describe the members of the human TLR family along with their natural modulators. Second, we illustrate our endeavors to discover TLR-targeted agents using comprehensive approaches. Specifically, a discussion of identification and characterization of new chemical entities, determination of modes of action, and further applications is presented. For instance, the TLR3 antagonist was first discovered through in silico screening, and the inhibitory activity was confirmed in murine cells. Considering the glycosylation on TLR3, a new direction for TLR3 modulator design was pointed out to target asparagine glycosylation. We have particularly focused on the discovery of TLR4 antagonists and have assessed their great potential in the clinical treatment of drug addiction and alcohol use disorders. In addition, we discuss multiple other popular and robust techniques for modulator discovery. Not only small organic modulators but also stapled peptides and peptidomimetics will attract more and more attention in the future. Finally, current challenges, opportunities, and future perspectives for TLR-targeted agents are also discussed.

Dendritic cells aggregate inflammation in experimental osteoarthritis through a toll-like receptor (TLR)-dependent machinery response to challenges

AimsDendritic cells (DCs) and Toll-like receptor (TLR) participate in mediating inflammation process. However, the functional role of TLR expressed on DCs in osteoarthritis (OA) development has not been defined yet. The purpose of this study was to investigate the role and mechanism of TLR and DCs in the progression of experimental osteoarthritis (OA). Materials and methodsExperimental OA model was induced by iodoacetate injection. Expressions of toll-like receptors in DCs of OA mice were detected by qRT-PCR and flow cytometry. TLR agonists lipopolysaccharide (LPS) and R848 or TLR antagonist FP7 were used, and the levels of TLRs and inflammatory cytokines were examined by qRT-PCR and ELISA. Key findingsThe expression levels of TLR family members were increased in DCs derived from synovial fluid of OA mice compared with the sham mice. In vitro, OA mice-derived DCs had increased production of inflammatory cytokine after TLR agonists LPS and R848 challenge, while TLR challenges did not affect DCs maturation. Inhibition of TLR by TLR antagonist FP7 blocked TLR challenges-induced increased inflammation in DCs. In mice, administration of FP7 attenuated LPS-induced inflammatory response and OA condition. SignificanceIncreased TLR expression in OA-derived DCs contributes to the inflammation condition and potentially acts as a therapeutic target for osteoarthritis.

IL1R8 Deficiency Drives Autoimmunity-Associated Lymphoma Development.

Chronic inflammation, including that driven by autoimmunity, is associated with the development of B-cell lymphomas. IL1R8 is a regulatory receptor belonging to the IL1R family, which negatively regulates NF-κB activation following stimulation of IL1R or Toll-like receptor family members. IL1R8 deficiency is associated with the development of severe autoimmune lupus-like disease in lpr mice. We herein investigated whether concomitant exacerbated inflammation and autoimmunity caused by the deficiency of IL1R8 could recapitulate autoimmunity-associated lymphomagenesis. We thus monitored B-cell lymphoma development during the aging of IL1R8-deficient lpr mice, observing an increased lymphoid cell expansion that evolved to diffuse large B-cell lymphoma (DLBCL). Molecular and gene-expression analyses showed that the NF-κB pathway was constitutively activated in Il1r8 -/-/lpr B splenocytes. In human DLBCL, IL1R8 had reduced expression compared with normal B cells, and higher IL1R8 expression was associated with a better outcome. Thus, IL1R8 silencing is associated with increased lymphoproliferation and transformation in the pathogenesis of B-cell lymphomas associated with autoimmunity.

A novel invertebrate toll-like receptor with broad recognition spectrum from thick shell mussel Mytilus coruscus

Toll-like receptors (TLRs) are a category of most well recognized pattern recognition molecules that act on a vital role in both innate and adaptive immunity. In the present study, a novel toll-like receptor (McTLRw) was identified and characterized in thick shell mussel Mytilus coruscus. McTLRw possesses one intracellular Toll/interleukin-1 (IL-1) receptor (TIR) domain, one transmembrane region (TM), one leucine rich repeat N-terminal domain (LRR_NT) and a few of leucine-rich repeats (LRRs), which all are common in typical TLRs. McTLRw transcripts were constitutively expressed in all examined tissues with higher expression levels in immune related tissues, and were significantly induced in haemocytes with the challenges of live Vibrio alginolyticus, lipopolysaccharide (LPS), peptidoglycans (PGN) and β-glucan (GLU), but not induced by polyinosinic-polycytidylic acid (poly I:C). rMcTLRw exhibited affinity to LPS, PGN and GLU while no affinity to poly I:C. Further, the downstream of TLR signaling pathway myeloid differentiation factor 88a (MyD88a), interleukin-1 receptor-associated kinase-4 (IRAK4) and tumor necrosis factor receptor-associated factor 6 (TRAF6) were significantly repressed in McTLRw silenced mussels while challenged with LPS. These results collectively indicated that McTLRw is one member of TLR family and involved in immune response to against invaders by taking participate in TLR mediated signaling pathway.

Expression Response Profiles of Toll-Like Receptor Family Members in Cyprinus Carpio after Lipopolysaccharide Stimulation, and Implication for Disease Control in Aquaculture

In this study, response profiles of 17 Toll-like receptors (TLRs) to lipopolysaccharide (LPS) stimulation were studied at mRNA levels in the liver of the common carp Cyprinus carpio. Three types of gene response profiles were observed in TLR family. The first pattern was that the expressions of some TLRs were initially up-regulated and then decreased with time. This finding indicated that the responses of these TLRs were sensitive to LPS stimulation, and it was suggested that these TLRs were involved in responding and coping with LPS, implying that these TLRs were important in immune defense from Gram-negative bacteria. The second pattern was that some TLR expressions showed no obvious change after LPS stimulation, demonstrating that they were not sensitive to LPS and probably did not recognize LPS, implying that these TLRs should not be regarded as the major receptors to be regulated to prevent disease caused by Gram-negative bacteria. The third pattern was that gene expressions of partial TLRs were significantly downregulated after a period of LPS stimulation, indicating that their gene expressions were inhibited by LPS action, and implying that these TLRs did not initiate the signal pathway for inflammation reaction to clear Gramnegative bacteria. This study is based on the different response patterns of TLRs to LPS, that imply that the sensitive response TLR genes to LPS might be selected as target genes regulated by drugs that control inflammation reaction of diseased fish in aquaculture.