The innate immune system is essential for the initial detection of invading viruses and subsequent activation of adaptive immunity. Three types pattern recognition receptors (PRRs) in innate immune cells play a pivotal role in the first line of host defense system. PRRs include Toll-like receptors (TLRs), RIG-I-like receptors(RLRs) and nucleotide-binding oligomerization domain (NOD)-like receptors (NLRs). PRRs recognize pathogen-associated molecular patterns(PAMPs) or danger-associated molecular patterns (DAMPs) to initiate and regulate innate and adaptive immune responses. Three types PRRs have their own features in ligand recognition and cellular location. Activated PRRs deliver signals to adaptor molecules (MyD88, TRIF, IRAK, IPS-1), which act as important messengers to activate downstream kinases (IKK complex, MAPKs, TBK1, RIP-1) and transcription factors (NF-kappaB, AP-1, IRF3), which produce effected molecules including cytokines, chemokines, inflammatory enzymes, and type I interferons. This review focuses on discussing PRRs signaling pathways and achievements in this field in order to provide beneficial strategies for human life and immune diseases prevention.
Animals ; Humans ; Immunity, Innate ; Receptors, Pattern Recognition ; genetics ; immunology ; metabolism ; Signal Transduction ; Virus Diseases ; immunology ; metabolism ; virology ; Virus Physiological Phenomena

Nucleotide-binding and oligomerization domain (NOD)-like receptors (NLRs) are pattern-recognition receptors similar to toll-like receptors (TLRs). While TLRs are transmembrane receptors, NLRs are cytoplasmic receptors that play a crucial role in the innate immune response by recognizing pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs). Based on their N-terminal domain, NLRs are divided into four subfamilies: NLRA, NLRB, NLRC, and NLRP. NLRs can also be divided into four broad functional categories: inflammasome assembly, signaling transduction, transcription activation, and autophagy. In addition to recognizing PAMPs and DAMPs, NLRs act as a key regulator of apoptosis and early development. Therefore, there are significant associations between NLRs and various diseases related to infection and immunity. NLR studies have recently begun to unveil the roles of NLRs in diseases such as gout, cryopyrin-associated periodic fever syndromes, and Crohn's disease. As these new associations between NRLs and diseases may improve our understanding of disease pathogenesis and lead to new approaches for the prevention and treatment of such diseases, NLRs are becoming increasingly relevant to clinicians. In this review, we provide a concise overview of NLRs and their role in infection, immunity, and disease, particularly from clinical perspectives.
Autophagy/immunology ; Carrier Proteins ; Humans ; *Immunity, Innate ; Inflammasomes ; Nod Signaling Adaptor Proteins/immunology/*metabolism ; Pathogen-Associated Molecular Pattern Molecules ; Receptors, Cytoplasmic and Nuclear/immunology/*metabolism ; Receptors, Pattern Recognition/*immunology ; *Signal Transduction ; Toll-Like Receptors/metabolism

Adaptive Immunity ; Bacterial Infections ; immunology ; prevention & control ; Biological Evolution ; Epithelial Cells ; immunology ; Gastrointestinal Diseases ; immunology ; prevention & control ; Humans ; Immunity, Innate ; Lymphocytes ; immunology ; Mucous Membrane ; cytology ; immunology ; Receptors, Pattern Recognition ; immunology ; Toll-Like Receptors ; immunology

BACKGROUNDTrichophyton rubrum (T. rubrum) represents the most important agent of dermatophytosis in humans. T. rubrum infection causes slight inflammation, and tends to be chronic and recurrent. It is suggested that it may result from the failure of epithelial cells to recognize T. rubrum effectively and initiate effective immune responses. The C-type lectin receptors (CLR) and toll-like receptors (TLR) are the two major pattern recognition receptors (PRRs) that recognize fungal components. Therefore, the purpose of the study was to analyze the expression of those PRRs and the cytokines in HaCaT cells stimulated with heat-inactivated T. rubrum conidia and hyphae, respectively.

METHODSHaCaT cells were unstimulated or stimulated with heat-inactivated T. rubrum conidia and hyphae (1×10(6) and 1.5×10(5) colony-forming unit (CFU) in 2 ml medium, respectively) for 6, 12 and 24 hours. The mRNA expression of PRRs involved in recognizing fungal pathogen-associated molecular patterns (PAMPs) and signaling molecules were measured by quantitative reverse transcription polymerase chain reaction (RT-PCR). Meanwhile, surface toll-like receptor (TLR) 2, TLR4 and Dectin-1 were analyzed by fluorescence-activated cell sorter (FACS) 24 hours after treatment. The cytokines were detected in cell culture supernatants of HaCaT cells in 12 and 24 hours after treatment.

RESULTSHaCaT cells constitutively expressed mRNA of membrane-bound TLR1, 2, 4 and 6, Dectin1 and DC-SIGN, but not Dectin-2 or Mincle. Heat-killed T. rubrum did not significantly upregulate gene transcriptions of the PRRs of HaCaT cells. Heat-inactivated T. rubrum conidia significantly reduced the surface expression of TLR2 and Dectin-1, and suppressed the secretions of interferon-inducible protein-10 (IP-10) and monocyte chemotactic protein-1 (MCP-1) of HaCaT cells, while heat-killed T. rubrum hyphae significantly induced the secretions of IP-10 and MCP-1.

CONCLUSIONThe cell-wall antigens of T. rubrum fail to activate transcriptional expression of PRRs and induce a lower immune response of HaCaT cells by limited cytokines secretion.

Cells, Cultured ; Cytokines ; biosynthesis ; Humans ; Keratinocytes ; immunology ; Lectins, C-Type ; genetics ; physiology ; RNA, Messenger ; analysis ; Receptors, Pattern Recognition ; genetics ; physiology ; Toll-Like Receptor 2 ; physiology ; Trichophyton ; immunology

Influenza A viruses (IAV) are highly contagious pathogens causing dreadful losses to human and animal, around the globe. IAVs first interact with the host through epithelial cells, and the viral RNA containing a 5'-triphosphate group is thought to be the critical trigger for activation of effective innate immunity via pattern recognition receptors-dependent signaling pathways. These induced immune responses establish the antiviral state of the host for effective suppression of viral replication and enhancing viral clearance. However, IAVs have evolved a variety of mechanisms by which they can invade host cells, circumvent the host immune responses, and use the machineries of host cells to synthesize and transport their own components, which help them to establish a successful infection and replication. In this review, we will highlight the molecular mechanisms of how IAV infection stimulates the host innate immune system and strategies by which IAV evades host responses.
Animals ; Humans ; Immune Evasion ; Immunity, Innate ; Influenza A virus ; immunology ; physiology ; Influenza, Human ; immunology ; metabolism ; pathology ; Receptors, Pattern Recognition ; metabolism ; Virus Attachment

Influenza A virus can create acute respiratory infection in humans and animals throughout the world, and it is still one of the major causes of morbidity and mortality in humans worldwide. Numerous studies have shown that influenza A virus infection induces rapidly host innate immune response. Influenza A virus triggers the activation of signaling pathways that are dependent on host pattern recognition receptors (PRRs) including toll like receptors (TLRs) and RIG-I like receptors (RLRs). Using a variety of regulatory mechanisms, these signaling pathways activate downstream transcript factors that control expression of various interferons and cytokines, such as type I and type III interferons. Thus, these interferons stimulate the transcript of relevant interferon-stimulated genes (ISGs) and expression of the antiviral proteins, which are critical components of host innate immunity. In this review, we will highlight the mechanisms by which influenza A virus infection induces the interferon-mediated host innate immunity.
Cytokines ; immunology ; DEAD Box Protein 58 ; DEAD-box RNA Helicases ; immunology ; Humans ; Immunity, Innate ; Influenza A virus ; Influenza, Human ; immunology ; Interferons ; immunology ; Receptors, Pattern Recognition ; immunology ; Signal Transduction ; Toll-Like Receptors ; immunology

The aim of this paper was to study the influence of triptolide in the immune response pathways of acquired immune deficiency syndrome( AIDS). Target proteins of triptolide and related genes of AIDS were searched in PubChem and Gene databases on line. Molecular networks and canonical pathways comparison analyses were performed by bioinformatics software( IPA). There were 15 targets proteins of triptolide and 258 related genes of AIDS. Close biological relationships of molecules of triptolide and AIDS were established by networks analysis. There were 21 common immune response pathways of triptolide and AIDS,including neuroinflammation signaling pathway,Th1 and Th2 activation pathway and role of pattern recognition receptors in recognition of bacteria and viruses. Triptolide stimulated immune response pathways by the main molecules of IFNγ,JAK2,NOD1,PTGS2,RORC. IFNγ is the focus nodes of triptolide and AIDS,and regulates genes of AIDS directly or indirectly. Triptolide may against AIDS by regulating molecules IFNγ in immune response pathways.
Acquired Immunodeficiency Syndrome ; drug therapy ; immunology ; Computational Biology ; Diterpenes ; pharmacology ; Epoxy Compounds ; pharmacology ; Gene Regulatory Networks ; Humans ; Interferon-gamma ; genetics ; Phenanthrenes ; pharmacology ; Receptors, Pattern Recognition ; immunology ; Signal Transduction ; T-Lymphocytes ; immunology

Adjuvants improve the adaptive immune response to a vaccine antigen by modulating innate immunity or facilitating transport and presentation. The selection of an appropriate adjuvant has become vital as new vaccines trend toward narrower composition, expanded application, and improved safety. Functionally, adjuvants act directly or indirectly on antigen presenting cells (APCs) including dendritic cells (DCs) and are perceived as having molecular patterns associated either with pathogen invasion or endogenous cell damage (known as pathogen associated molecular patterns [PAMPs] and damage associated molecular patterns [DAMPs]), thereby initiating sensing and response pathways. PAMP-type adjuvants are ligands for toll-like receptors (TLRs) and can directly affect DCs to alter the strength, potency, speed, duration, bias, breadth, and scope of adaptive immunity. DAMP-type adjuvants signal via proinflammatory pathways and promote immune cell infiltration, antigen presentation, and effector cell maturation. This class of adjuvants includes mineral salts, oil emulsions, nanoparticles, and polyelectrolytes and comprises colloids and molecular assemblies exhibiting complex, heterogeneous structures. Today innovation in adjuvant technology is driven by rapidly expanding knowledge in immunology, cross-fertilization from other areas including systems biology and materials sciences, and regulatory requirements for quality, safety, efficacy and understanding as part of the vaccine product. Standardizations will aid efforts to better define and compare the structure, function and safety of adjuvants. This article briefly surveys the genesis of adjuvant technology and then re-examines polyionic macromolecules and polyelectrolyte materials, adjuvants currently not known to employ TLR. Specific updates are provided for aluminum-based formulations and polyelectrolytes as examples of improvements to the oldest and emerging classes of vaccine adjuvants in use.
Adaptive Immunity ; Adjuvants, Immunologic ; Allergy and Immunology ; Aluminum Hydroxide ; Aluminum* ; Antigen Presentation ; Antigen-Presenting Cells ; Bias (Epidemiology) ; Chitosan ; Colloids ; Dendritic Cells ; Emulsions ; Immunity, Innate ; Ligands ; Nanoparticles ; Polymers ; Receptors, Pattern Recognition ; Salts* ; Systems Biology ; Toll-Like Receptors ; Vaccines

Phagocytosis and innate immune responses to solid structures are topics of interest and debate. Alum, monosodium urate, calcium pyrophosphate dehydrate, silica and by extension all solid entities draw varying degrees of attention from phagocytes, such as antigen presenting cells. For some, innocuous soluble metabolites turn into fierce irritants upon crystallization, pointing to divergent signaling mechanisms of a given substance in its soluble and solid states. Over the years, many mechanisms have been proposed, including phagocytic receptors, toll like receptors, and NACHT-LRRs (NLRs), as well as several other protein structure mediated recognition of the solids. Is there a more general mechanism for sensing solids? In this perspective, I present an alternative view on the topic that membrane lipids can engage solid surfaces, and the binding intensity leads to cellular activation. I argue from the stands of evolution and biological necessity, as well as the progression of our understanding of cellular membranes and phagocytosis. The effort is to invite debate of the topic from a less familiar yet equally thrilling viewing angle.
Adjuvants, Immunologic ; Alum Compounds ; Animals ; Antigen-Presenting Cells ; cytology ; immunology ; Biological Evolution ; Calcium Pyrophosphate ; immunology ; Cell Membrane ; immunology ; Humans ; Immunity, Innate ; Membrane Lipids ; immunology ; Phagocytes ; cytology ; immunology ; Phagocytosis ; immunology ; Phase Transition ; Receptors, Pattern Recognition ; immunology ; Signal Transduction ; immunology ; Silicon Dioxide ; immunology ; Uric Acid ; immunology