fsl-1-lipoprotein--synthetic and Inflammation

Toll-like receptors (TLRs) are a group of sensory receptors which are capable of recognizing a microbial invasion and activating innate immune system responses, including inflammatory responses, in both immune and non-immune cells. However, TLR functions in chick myoblasts, which are myogenic precursor cells contributing to skeletal muscle development and growth, have not been studied. Here, we report the expression patterns of TLR genes as well as TLR ligand-dependent transcriptions of interleukin (IL) genes in primary-cultured chick myoblasts. Almost TLR genes were expressed both in layer and broiler myoblasts but TLR1A was detected only in embryonic layer chick myoblasts. Chick TLR1/2 ligands, Pam

Topics: Animals; Avian Proteins; Bird Diseases; Chick Embryo; Chickens; Diglycerides; Gene Expression Regulation, Developmental; Immunity, Innate; Inflammation; Lipopeptides; Lipopolysaccharides; Muscle, Skeletal; Myoblasts; Oligopeptides; Toll-Like Receptors; Transcriptome

Self-extracellular RNA (eRNA), released from stressed or injured cells upon various pathological situations such as ischemia-reperfusion-injury, has been shown to act as an alarmin by inducing procoagulatory and proinflammatory responses. In particular, M1-polarization of macrophages by eRNA resulted in the expression and release of a variety of cytokines, including tumor necrosis factor (TNF)-α or interleukin-6 (IL-6). The present study now investigates in which way self-eRNA may influence the response of macrophages towards various Toll-like receptor (TLR)-agonists. Isolated agonists of TLR2 (Pam2CSK4), TLR3 (PolyIC), TLR4 (LPS), or TLR7 (R848) induced the release of TNF-α in a concentration-dependent manner in murine macrophages, differentiated from bone marrow-derived stem cells by mouse colony stimulating factor. Here, the presence of eRNA shifted the dose-response curve for Pam2CSK4 (Pam) considerably to the left, indicating that eRNA synergistically enhanced the cytokine liberation from macrophages even at very low Pam-levels. The synergistic activation of TLR2 by eRNA/Pam was duplicated by other TLR2-agonists such as FSL-1 or Pam3CSK4. In contrast, for TLR4-agonists such as LPS a synergistic effect of eRNA was much weaker, and was not existent for TLR3-, or TLR7-agonists. The synergistic eRNA/Pam action was dependent on the NFκB-signaling pathway as well as on p38MAP- and MEK1/ERK-kinases and was prevented by predigestion of eRNA with RNase1 or by antibodies against TLR2. Thus, the presence of self-eRNA as alarming molecule sensitizes innate immune responses towards pathogen-associated molecular patterns (PAMPs) in a synergistic way and may thereby contribute to the differentiated outcome of inflammatory responses.

Topics: Animals; Cytokines; Diglycerides; Extracellular Space; Inflammation; Lipopeptides; Macrophages; Mice, Inbred C57BL; Oligopeptides; Pathogen-Associated Molecular Pattern Molecules; RNA; Signal Transduction; Time Factors; Toll-Like Receptors

Infection and inflammation stimulate pro-inflammatory cytokines, prostaglandins and matrix metalloproteinase (MMP)-9, which play a central role in myometrial contractions and rupture of fetal membranes. In human and mouse immune cells, activating transcription factor 3 (ATF3) is a negative regulator of inflammation. No studies have examined the role of ATF3 in human labour.. Primary amnion cells were used to determine the effect of interleukin (IL)-1β and the bacterial product fibroblast-stimulating lipopeptide (fsl-1) on ATF3 expression, and the effect of ATF3 siRNA on pro-labour mediators. ATF3 expression was assessed in fetal membranes from non-labouring and labouring women at term and preterm, and after preterm pre-labour rupture of membranes (PPROM).. IL-1β and fsl-1 significantly increased ATF3 expression. Silencing ATF3 significantly increased IL-1β- or fsl-1-induced expression of pro-inflammatory cytokines (TNF-α, IL-1α, IL-1β, IL-6) and chemokines (IL-8 and monocyte chemoattractant protein-1 (MCP-1)); cyclooxygenase-2 (COX-2) mRNA expression and prostaglandin PGF. ATF3 is a negative regulator of inflammation in human fetal membranes; in primary amnion cells, ATF3 expression is induced by IL-1β and fsl-1, and ATF3 silencing further exacerbates the inflammatory response when stimulated with these factors. Subsequently, ATF3 expression is decreased in fetal membranes after term labour and with preterm chorioamnionitis, conditions closely associated with inflammation and infection. Our data suggest that ATF3 may play a role in the terminal processes of human labour and delivery.

Topics: Activating Transcription Factor 3; Cell Line; Chorioamnionitis; Cytokines; Diglycerides; Extraembryonic Membranes; Female; Fetal Membranes, Premature Rupture; Humans; Inflammation; Interleukin-1beta; Labor, Obstetric; Oligopeptides; Pregnancy

Systemic lupus erythematosus is characterized by dysregulated activation of T and B cells and autoantibodies to nuclear antigens and, in some cases, lipid antigens. Liposomes with nonbilayer phospholipid arrangements induce a disease resembling human lupus in mice, including IgM and IgG antibodies against nonbilayer phospholipid arrangements. As the effect of these liposomes on the innate immune response is unknown and innate immune system activation is necessary for efficient antibody formation, we evaluated the effect of these liposomes on Toll-like receptor (TLR) signaling, cytokine production, proinflammatory gene expression, and T, NKT, dendritic, and B cells. Liposomes induce TLR-4- and, to a lesser extent, TLR-2/TLR-6-dependent signaling in TLR-expressing human embryonic kidney (HEK) cells and bone marrow-derived macrophages. Mice with the lupus-like disease had increased serum concentrations of proinflammatory cytokines, C3a and C5a; they also had more TLR-4-expressing splenocytes, a higher expression of genes associated with TRIF-dependent TLR-4-signaling and complement activation, and a lower expression of apoptosis-related genes, compared to healthy mice. The percentage of NKT and the percentage and activation of dendritic and B2 cells were also increased. Thus, TLR-4 and TLR-2/TLR-6 activation by nonbilayer phospholipid arrangements triggers an inflammatory response that could contribute to autoantibody production and the generation of a lupus-like disease in mice.

Topics: Animals; Autoantibodies; Chlorpromazine; Cytokines; Diglycerides; Disease Models, Animal; Female; Flagellin; Gene Expression Regulation; HEK293 Cells; Humans; Immunoglobulin G; Immunoglobulin M; Inflammation; Lipopolysaccharides; Liposomes; Lupus Erythematosus, Systemic; Mice; Mice, Inbred BALB C; Oligopeptides; Phosphatidic Acids; Phosphatidylcholines; Phosphatidylserines; Toll-Like Receptor 2; Toll-Like Receptor 4; Toll-Like Receptor 6

CD36 participates in macrophage internalization of a variety of particles, and has been implicated in inflammatory responses to many of these ligands. To what extent CD36 cooperates with other receptors in mediating these processes remains unclear. Because CD36 has been shown to cooperate with TLR2, we investigated the roles and interactions of CD36 and TLRs in inflammation and phagocytosis. Using Ab-induced endocytosis of CD36 and phagocytosis of erythrocytes displaying Abs to CD36, we show that selective engagement and internalization of this receptor did not lead to proinflammatory cytokine production by primary human and murine macrophages. In addition, CD36-mediated phagocytosis of Plasmodium falciparum malaria-parasitized erythrocytes (PEs), which contain parasite components that activate TLRs, also failed to induce cytokine secretion from primary macrophages. Furthermore, we demonstrate that CD36-mediated internalization did not require TLR2 or the TLR-signaling molecule IRAK4. However, macrophage pretreatment with TLR agonists markedly stimulated particle uptake via CD36. Similarly, PE uptake was unaffected by TLR deficiency, but in wild-type cells was increased by pretreatment with purified P. falciparum glycosylphosphatidylinositols, which activate TLR2. Our findings indicate that CD36 must cooperate with other receptors such as TLRs to participate in cytokine responses. Although purified P. falciparum components activate TLRs, CD36-mediated internalization of intact PEs is not inflammatory. Further, CD36 mediates internalization of particles, including PEs, independently of TLR signaling, but can functionally cooperate with TLRs to enhance internalization.

Topics: Animals; CD36 Antigens; Cytokines; Diglycerides; Erythrocytes; Humans; Inflammation; Interleukin-1 Receptor-Associated Kinases; Lipopeptides; Macrophages; Malaria, Falciparum; Membrane Proteins; Mice; Mice, Inbred C57BL; Mice, Knockout; Oligopeptides; Phagocytosis; Plasmodium falciparum; Protozoan Proteins; Toll-Like Receptor 2

Macrophage-activating lipopeptide-2 (MALP-2) from Mycoplasma fermentans has been identified as a pathogen-associated molecular pattern of Mycoplasmas that causes activation of the innate immune system through the activation of the heterodimeric Toll-like receptors (TLRs)-2 and -6. The aim of this study was to characterize the ability of MALP-2 and a synthetic analog fibroblast-stimulating lipopeptide-1 (FSL-1; represents the NH2-terminal sequence of a lipoprotein from M. salivarium) to act as exogenous pyrogens, to induce formation of cytokines (endogenous pyrogens), and to cause sickness behavior, such as depressed motor activity, anorexia, and adipsia. For this purpose, body temperature, activity, food intake, and water intake were recorded for 3 days by use of telemetry devices in several groups of rats treated with MALP-2/FSL-1 or the respective control solutions. Intraperitoneal injections of FSL-1 caused fever at doses of 10 or 100 microg/kg, which was preceded by a pronounced phase of hypothermia in response to a dose of 1,000 microg/kg. The maximal fever (a peak of 1.5 degrees C above baseline) was caused by the 100 microg/kg dose with almost identical responses to both MALP-2 and FSL-1. Fever was accompanied by pronounced rises of the proinflammatory cytokines TNF and IL-6 in plasma. Treatment with the TLR-2 and -6 agonists further induced a dose-dependent manifestation of anorexia and adipsia, as well as a reduction of motor activity. We could thus demonstrate that activation of TLR-2 and -6 can induce systemic inflammation in rats accompanied by the classical signs of brain-controlled illness responses.

Topics: Animals; Anorexia; Body Weight; Brain; Circadian Rhythm; Diglycerides; Drinking; Fever; Inflammation; Lipopeptides; Male; Motor Activity; Oligopeptides; Rats; Rats, Wistar; Toll-Like Receptor 2; Toll-Like Receptor 6