In protection against microbes, an organism recognizes the pathogen associated molecular pattern (PAMP) on microbes by pattern recognition receptor (PRR). Toll-like receptor is called innate immunity. A family of cell membrane receptor was found in recent years that can mediate innate immune responses through the activation of a series of immune-related genes. In phylogenesis, it is highly conservative. However, its functions are getting more diversified with the complication of the immune functions of organisms.
Animals ; Humans ; Immunity ; Membrane Glycoproteins ; immunology ; Phylogeny ; Receptors, Cell Surface ; immunology ; Toll-Like Receptors

The innate immune system provides a first line of defense against invading pathogens, in which the pattern recognition receptors (PRR) recognize pathogen-associated molecular patterns (PAMP) and initiate the downstream signaling pathways to eliminate the encountered pathogens. There are two main classes of such signaling pathways: NOD-like receptor (NLR) signaling pathway and Toll-like receptor (TLR) signaling pathway. The microbial pathogens under selective pressure have evolved numerous mechanisms to avoid and/or manipulate the NLR and TLR signal transduction for survival and replication. To evade the NLR signaling pathway, pathogens interfere and/or inhibit inflammasome activation in innate immune cells by producing virulence factors or reducing PAMPs expression. The mechanisms for pathogens to evade TLR signaling pathway include: inhibition of mitogen activated protein kinases (MAPKs) cascade reaction, inhibition of NF-КB activation, and interference of down-stream signal transduction by producing Toll/interleukin-1 receptor (TIR)-containing proteins which bind directly with TLRs or adaptor proteins in the signaling pathway.
Immunity, Innate ; NLR Proteins ; immunology ; Receptors, Interleukin-1 ; metabolism ; Signal Transduction ; Toll-Like Receptors ; immunology

Infection and antibiotic multidrug resistance have become the focal issue in clinical treatment of acute leukemia and will make anti-infection therapy facing to new challenge. Toll-like receptor (TLR) has been found a newly innate immunoreceptor. It is significant in immune response. Along with further investigation of TLR, infection and anti-infection immunity theory would gain a new breakthrough and play a guiding role in clinical treatment of acute leukemia complicated with infection. In this review, the progress in the research of TLR and its expression in acute leukemia complicated with infection were summarized.
Acute Disease ; Humans ; Infection ; complications ; immunology ; Leukemia ; complications ; immunology ; metabolism ; Toll-Like Receptor 4 ; immunology ; metabolism ; Toll-Like Receptors ; immunology ; metabolism

Liver Diseases ; immunology ; metabolism ; Signal Transduction ; Toll-Like Receptors ; immunology ; metabolism

Toll like receptor (TLR) can specifically recgnize pathogen-associated molecular patterns (PAMPs) and is considered as an important link between innate and adaptive immunity. It has been shown that TLR plays an important role in the pathogenesis and pathophysiology of a variety of skin diseases. Moreover, TLR agonists have exhibited promising therapeutic effects on the disease models and are expected to be novel vaccine adjuvants. Investigations of the underlying mechanism will give new insights into these diseases. This review will discuss the relationship between TLR and pathogenesis and management of some cutaneous diseases.
Adaptive Immunity ; Immunity, Innate ; Signal Transduction ; Skin Diseases ; immunology ; metabolism ; Toll-Like Receptors ; immunology ; metabolism ; physiology

Toll-like receptors (TLRs) are pivotal components of the innate immune response, which is responsible for eradicating invading microorganisms through the induction of inflammatory molecules. These receptors are also involved in responding to harmful endogenous molecules and have crucial roles in the activation of the innate immune system and shaping the adaptive immune response. However, TLR signaling pathways must be tightly regulated because undue TLR stimulation may disrupt the fine balance between pro- and anti-inflammatory responses. Such disruptions may harm the host through the development of autoimmune and inflammatory diseases, such as rheumatoid arthritis and systemic lupus erythematosus. Several studies have investigated the regulatory pathways of TLRs that are essential for modulating proinflammatory responses. These studies reported several pathways and molecules that act individually or in combination to regulate immune responses. In this review, we have summarized recent advancements in the elucidation of the negative regulation of TLR signaling. Moreover, this review covers the modulation of TLR signaling at multiple levels, including adaptor complex destabilization, phosphorylation and ubiquitin-mediated degradation of signal proteins, manipulation of other receptors, and transcriptional regulation. Lastly, synthetic inhibitors have also been briefly discussed to highlight negative regulatory approaches in the treatment of inflammatory diseases.
Animals ; Cytokines/biosynthesis ; Humans ; Ligands ; Models, Immunological ; Signal Transduction/*immunology ; Toll-Like Receptors/antagonists & inhibitors/*metabolism

Animals ; Hepatitis B, Chronic ; immunology ; Humans ; Immune System Phenomena ; Toll-Like Receptors

Dendritic cells (DCs), the most potent antigen-presenting cells, recognize pathogen by Toll-like receptors (TLRs) and serve as the bridge between the innate and the adaptive immune responses. TLRs-mediated signal transduction plays a crucial role in the functional maturation of DCs. This review summarizes the research progress on the expression and function of TLRs in DCs.
Dendritic Cells ; immunology ; metabolism ; Humans ; Immunity, Innate ; Signal Transduction ; Toll-Like Receptors ; metabolism ; physiology

OBJECTIVETo investigate the expression of TLR4/2 mRNA in neonatal cord blood mononuclear cells (MNC).

METHODSForty-six neonates without asphyxia and 40 neonates with asphyxia were divided into groups depending on the gestational age. In the neonates without asphyxia, there were 18 full term infants (the gestational age > or = 37 weeks), 16 preterm infants whose gestational age was > or = 32 weeks but < 37 weeks, and 12 preterm infants whose gestational age was < 32 weeks. In the neonates with asphyxia, 11 were full term infants, 15 were preterm infants whose gestational age was > or = 32 weeks but < 37 weeks and 14 were preterm infants at gestational age < 32 weeks. MNCs were separated and cultured with LPS (1 microg/ml) for 3 h. Cells were collected for analysis of gene expression of TLR4/2 by RT-PCR technique. Cell supernatants were taken to measure TNF-alpha production following the ELISA protocol. Fifteen healthy adults were enrolled into the control group. In addition, the Pearson correlation analyses were carried out between the levels of TLR4, TLR2 mRNA and the levels of TNF-alpha.

RESULTSIn the neonates without asphyxia, TLR4, TLR2 mRNA and TNF-alpha levels were 0.75 +/- 0.12, 0.63 +/- 0.08, 2502.6 +/- 273.1 ng/L, separately, in the full term infants, 0.37 +/- 0.04, 0.32 +/- 0.03, 1218.8 +/- 145.7 ng/L, separately, in the preterm infants whose gestational ages were > or = 32 weeks but < 37 weeks, and 0.26 +/- 0.03, 0.20 +/- 0.03, 811.8 +/- 105.2 ng/L separately, in the preterm infants whose gestational ages were < 32 weeks. In the neonates with asphyxia, TLR4, TLR2 mRNA and TNF-alpha levels were 0.58 +/- 0.07, 0.50 +/- 0.06, 1946.4 +/- 244.2 ng/L, separately, in the full term infants, 0.29 +/- 0.03, 0.26 +/- 0.03, 970.0 +/- 94.3 ng/L, separately, in the preterm infants whose gestational age was > or = 32 weeks but < 37 weeks, and 0.17 +/- 0.02, 0.14 +/- 0.02, 652.6 +/- 60.3 ng/L, separately, in the preterm infants whose gestational age was < 32 weeks. The levels of TLR4, TLR2 mRNA and TNF-alpha in the adults were 2.71 +/- 0.75, 2.61 +/- 0.33, 9270.1 +/- 1098.3 ng/L, separately. In the preterm infants and full term infants, the levels of TLR4, TLR2 mRNA and TNF-alpha were lower in comparison to the adults. The lower the gestational age, the lower the levels of TLR4, TLR2 mRNA and TNF-alpha. There were significant differences between the levels of TLR4, TLR2 mRNA and TNF-alpha of the neonates without asphyxia and those of the neonates with asphyxia. In the neonates with asphyxia, the levels of TLR4, TLR2 mRNA and TNF-alpha were lower than those in the neonates without asphyxia (P < 0.01). Whether the neonates were asphyxic or not, the levels of TLR4, TLR2 were paralleled with the levels of TNF-alpha.

CONCLUSIONSThe expression of TLRs in the neonates, especially in the preterm infants was lower than that in the adults, which probably contributes to the susceptibility of neonates to infections.

Blood Cells ; metabolism ; Gene Expression ; Humans ; Infant ; Infant, Newborn ; RNA, Messenger ; genetics ; Toll-Like Receptor 2 ; metabolism ; Toll-Like Receptors ; metabolism ; Tumor Necrosis Factor-alpha ; immunology

Toll-like receptors (TLRs) are the archetypal pattern recognition receptors in sensing exogenous pathogens. Activation of TLRs is a first line of defense of the immune system, leading to the activation and recruitment of neutrophils and macrophages to sites of infection and enhances antimicrobial activity. The TLR signaling through different intracellular molecules, such as MAP kinases and IkappaB kinases which are conserved signaling elements for many receptors, leads to a distinct set of proinflammatory gene expressions. However, how these pathways differentially and precisely control the transcription of identical genes remains largely unknown. Our review focuses on the details of up-to- date signaling molecules including negative regulators and their role in controlling innate immune response. We also stress the importance of developing systemic approaches for the global understanding of TLR signaling so that appropriate drug therapeutic targets can be identified for regulating inflammatory diseases.
Adaptor Proteins, Signal Transducing/*immunology ; Animals ; Humans ; MAP Kinase Signaling System/*immunology ; Receptor Cross-Talk ; Receptors, Interleukin-1/immunology ; *Signal Transduction ; Toll-Like Receptors/*immunology