Pam3CSK4

The inflammatory cytokine effect of Pam3CSK4 TLR2 agonist alone or in combination with Leishmania infantum antigen on ex-vivo whole blood from sick and resistant dogs.[Pubmed:28288677]

Parasit Vectors. 2017 Mar 13;10(1):123.

BACKGROUND: A wide spectrum of clinical manifestations and immune responses exist in canine L. infantum infection. Ibizan hounds are more "resistant" to disease than other dog breeds. Recognition of pathogen-associated molecule patterns by toll like receptors (TLRs) rapidly triggers a variety of anti-microbial immune responses through the induction of pro-inflammatory cytokines such as TNF-alpha and IL-6 which may play an important role in controlling Leishmania infection. The main objective of this study was to investigate and compare the effect of a TLR2 agonist (TLR2a) alone or in combination with L. infantum antigen (LSA) on ex vivo whole blood cytokine production from healthy seronegative IFN-gamma non-producer dogs from an area of low in canine leishmaniosis endemicity (n = 11); sick seropositive dogs with low production of IFN-gamma (n = 17) and healthy seronegative or low positive Ibizan hounds with a predominant IFN-gamma production (n = 21) from a highly endemic area. Whole blood was stimulated with medium alone (O), LSA, concanavalin A, TLR2 (Pam3CSK4) receptor agonist (O + TLR2a) and TLR2a and LSA (LSA + TLR2a) for 48 h. Supernatants were harvested for measurement of canine TNF-alpha and IL-6 cytokines by ELISA. RESULTS: A significant increase of TNF-alpha was found in the supernatants of stimulated blood from all groups (O + TLR2a and LSA + TLR2a) when compared with medium alone. A similar pattern was observed for IL-6. Interestingly, a significant increase of TNF-alpha production was only observed when stimulation with LSA + TLR2a was compared with TLR2a alone in Ibizan hounds. A significant increase of TNF-alpha production was observed with stimulation of LSA + TLR2a when compared with LSA in all groups. Significantly higher concentrations of TNF-alpha and IL-6 were detected in Ibizan hounds, especially for the O + TLR2a and LSA + TLR2a treatments compared with other groups. CONCLUSIONS: This study demonstrated that TLR2a alone enhances the production of the inflammatory cytokines TNF-alpha and IL-6 in sick, "resistant" and healthy non-infected dogs. In addition, a combination of LSA+TLR2a promoted a synergistic pro-inflammatory effect with TNF-alpha in Ibizan hounds but not in seropositive sick dogs and seronegative healthy dogs. These findings might suggest the importance of Pam3CSK4 as a possible immunomodulator for CanL.

Detection of the Lipopeptide Pam3CSK4 Using a Hybridized Toll-like Receptor Electrochemical Sensor.[Pubmed:28374588]

Anal Chem. 2017 May 2;89(9):4882-4888.

Electrochemical detection of Pam3CSK4, a synthetic triacylated lipopeptide that mimics the structural moieties of its natural Gram negative bacterial pathogen-associated molecular pattern (PAMP) counterpart, has been achieved using hybridized toll-like receptors (TLR) combining TLR1 and TLR2 onto a single sensor surface. These sensors represent the first hybridized TLR sensors. The limit of detection for Pam3CSK4 attained was 7.5 mug/mL, which is within the same order of magnitude for that of the more labor-intensive and time-consuming cell-assay technique, 2.0 mug/mL. The results gathered in these electrochemical experiments show that sensors fabricated by immobilizing a mixture of cooperative TLR1 and -2 generate higher responses when exposed to the analyte in comparison to the control sensors fabricated using pure TLR1 or -2 standalone. A PAMP selectivity test was carried out in line with our inspiration from the mammalian innate immune response. TLRs1-5 as standalone biorecognition elements and the hybridized "TLR1 and 2" sensor surface were investigated, understanding the known TLR-PAMP interactions, through the exploitation of this electrochemical sensor fabrication technique. The experimental result is consistent with observations from previously published in vivo and in vitro studies, and it is the first demonstration of the simultaneous evaluation of electrochemical responses from multiple, unique fabricated TLR sensor surfaces against the same analyte.

Toll-Like Receptor 2 Agonist Pam3CSK4 Alleviates the Pathology of Leptospirosis in Hamster.[Pubmed:27620721]

Infect Immun. 2016 Nov 18;84(12):3350-3357.

Leptospirosis, caused by pathogenic spirochetes, is a zoonotic disease of global importance. The detailed pathogenesis of leptospirosis is still unclear, which limits the ideal treatment of leptospirosis. In this study, we analyzed the expression of Toll-like receptor 2 (TLR2) and TLR4 in target organs of both resistant mice and susceptible hamsters after Leptospira interrogans serovar Autumnalis infection. TLR2 but not TLR4 transcripts in mouse organs contrasted with delayed induction and overexpression in hamster organs. Coinjection of leptospires and the TLR2 agonist Pam3CSK4 into hamsters improved their survival rate, alleviated tissue injury, and decreased the abundance of leptospires in target organs. The production of interleukin-10 (IL-10) from tissues was enhanced in hamsters of the group coinjected with leptospires and Pam3CSK4 compared with the leptospira-injected group. Similarly, IL-10 levels in TLR2-deficient mice were lower than those in wild-type mice. A high ratio of IL-10/tumor necrosis factor alpha (TNF-alpha) levels was found in both infected wild-type mice and hamsters coinjected with leptospires and Pam3CSK4. Moreover, TLR2-dependent IL-10 expression was detected in peritoneal macrophages after leptospira infection. Our data demonstrate that coinjection of leptospires and Pam3CSK4 alleviates the pathology of leptospirosis in hamsters; this effect may result from the enhanced expression of TLR2-dependent IL-10.

Control of Methicillin-Resistant Staphylococcus aureus Pneumonia Utilizing TLR2 Agonist Pam3CSK4.[Pubmed:26974438]

PLoS One. 2016 Mar 14;11(3):e0149233.

The spread of methicillin-resistant Staphylococcus aureus (MRSA) is a critical health issue that has drawn greater attention to the potential use of immunotherapy. Toll-like receptor 2 (TLR2), a pattern recognition receptor, is an essential component in host innate defense system against S. aureus infection. However, little is known about the innate immune response, specifically TLR2 activation, against MRSA infection. Here, we evaluate the protective effect and the mechanism of MRSA murine pneumonia after pretreatment with Pam3CSK4, a TLR2 agonist. We found that the MRSA-pneumonia mouse model, pretreated with Pam3CSK4, had reduced bacteria and mortality in comparison to control mice. As well, lower protein and mRNA levels of TNF-alpha, IL-1beta and IL-6 were observed in lungs and bronchus of the Pam3CSK4 pretreatment group. Conversely, expression of anti-inflammatory cytokine IL-10, but not TGF-beta, increased in Pam3CSK4-pretreated mice. Our additional studies showed that CXCL-2 and CXCL1, which are necessary for neutrophil recruitment, were less evident in the Pam3CSK4-pretreated group compared to control group, whereas the expression of Fcgamma receptors (Fcgamma/) and complement receptors (CR1/3) increased in murine lungs. Furthermore, we found that increased survival and improved bacterial clearance were not a result of higher levels of neutrophil infiltration, but rather a result of enhanced phagocytosis and bactericidal activity of neutrophils in vitro and in vivo as well as increased robust oxidative activity and release of lactoferrin. Our cumulative findings suggest that Pam3CSK4 could be a novel immunotherapeutic candidate against MRSA pneumonia.

MF59 and Pam3CSK4 boost adaptive responses to influenza subunit vaccine through an IFN type I-independent mechanism of action.[Pubmed:22351935]

J Immunol. 2012 Apr 1;188(7):3088-98.

The innate immune pathways induced by adjuvants required to increase adaptive responses to influenza subunit vaccines are not well characterized. We profiled different TLR-independent (MF59 and alum) and TLR-dependent (CpG, resiquimod, and Pam3CSK4) adjuvants for the ability to increase the immunogenicity to a trivalent influenza seasonal subunit vaccine and to tetanus toxoid (TT) in mouse. Although all adjuvants boosted the Ab responses to TT, only MF59 and Pam3CSK4 were able to enhance hemagglutinin Ab responses. To identify innate immune correlates of adjuvanticity to influenza subunit vaccine, we investigated the gene signatures induced by each adjuvant in vitro in splenocytes and in vivo in muscle and lymph nodes using DNA microarrays. We found that flu adjuvanticity correlates with the upregulation of proinflammatory genes and other genes involved in leukocyte transendothelial migration at the vaccine injection site. Confocal and FACS analysis confirmed that MF59 and Pam3CSK4 were the strongest inducers of blood cell recruitment in the muscle compared with the other adjuvants tested. Even though it has been proposed that IFN type I is required for adjuvanticity to influenza vaccines, we found that MF59 and Pam3CSK4 were not good inducers of IFN-related innate immunity pathways. By contrast, resiquimod failed to enhance the adaptive response to flu despite a strong activation of the IFN pathway in muscle and lymph nodes. By blocking IFN type I receptor through a mAb, we confirmed that the adjuvanticity of MF59 and Pam3CSK4 to a trivalent influenza vaccine and to TT is IFN independent.

Toll-like receptor ligands induce the expression of interferon-gamma and interleukin-17 in chicken CD4+ T cells.[Pubmed:23116495]

BMC Res Notes. 2012 Nov 1;5:616.

BACKGROUND: Toll-like receptors (TLRs) are evolutionarily conserved pattern recognition receptors that mediate host responses to pathogens. To date, at least 10 different TLRs have been identified in chickens including TLR2, which binds lipopeptides and other similar ligands such as Pam3CSK4, TLR3, which binds double stranded RNA as well as synthetic molecules such as poly I:C, TLR4, which binds lipopolysaccharide (LPS), and TLR21, which binds CpG DNA motifs. In mammals, TLRs have been detected on CD4+ T cells where they mediate cellular survival, proliferation and the production of cytokines. However, the TLR-mediated responses in chicken CD4+ T cells remain to be determined. As such, the objective of the present study was to elucidate the kinetics of cytokine response to several different TLR ligands in chicken CD4+ T cells. RESULTS: The results suggest that these cells express TLRs 2, 3, 4 and 21 at the transcript level, and treatment with ligands for these TLRs significantly influenced the expression of the cytokines interferon (IFN)-gamma and interleukin (IL)-17, but not IL-4, IL-10 and IL-13. Specifically, treatment with Pam3CSK4, poly I:C and LPS up-regulated IFN-gamma transcripts, while CpG ODN significantly down-regulated them. In contrast, at least one dose of each of the TLR ligands, except for Pam3CSK4, significantly down-regulated IL-17 transcripts. CONCLUSION: Chicken CD4+ T cells respond to ligands for TLRs 2, 3, 4 and 21 by up-regulating or down-regulating cytokine transcripts. Future studies may consider exploring how these TLR ligands may modulate other effector functions in chicken CD4+ T cells, as well as in other T cell subsets such as CD8+ T cells.

Lipopeptides are effective stimulators of tyrosine phosphorylation in human myeloid cells.[Pubmed:1312332]

Biochem J. 1992 Mar 1;282 ( Pt 2):551-7.

Synthetic lipopeptide analogues of the N-terminus of bacterial lipoprotein are effective activators of macrophages, neutrophils and lymphocytes. We studied the effect of the lipopeptide N-palmitoyl-S-[2,3-bis(palmitoyloxy)-(2RS)-propyl]- (R)-cysteinyl-(S)-seryl-(S)-lysyl-(S)-lysyl-(S)-lysyl-(S)-lysine [Pam3Cys-Ser-(Lys)4] on tyrosine phosphorylation in dibutyryl-cyclic-AMP-differentiated HL-60 cells, using anti-phosphotyrosine antibodies. Pam3Cys-Ser-(Lys)4 concentration-dependently stimulated tyrosine phosphorylation of 100/110 kDa and 60 kDa proteins and, to a lesser extent, of 55 kDa and 70/75 kDa proteins. Half-maximal and maximal effects were observed at concentrations of 1-6 and 5-50 micrograms/ml respectively. The lipopeptide-induced increase in phosphorylation was rapid and transient, with a peak response after 30-60 s. The lipopeptide (2S)-2-palmitoylamino-6-palmitoyloxymethyl-7-palmitoyloxy heptanoyl-Ser-(Lys)4 [Pam3Ahh-Ser-(Lys)4] was as potent as Pam3Cys-Ser(Lys)4, whereas (2S,6S)-2-palmitoylamino-6,7-bis(palmitoyloxy)heptanoyl++ +-Ser-(Lys)4 [Pam3Adh-Ser-(Lys)4] and Pam3Cys-Ser-Gly did not induce tyrosine phosphorylation. Lipopeptide-induced tyrosine phosphorylation was not affected by treatment of cells with pertussis toxin. Neither phorbol 12-myristate 13-acetate nor A23187 induced tyrosine phosphorylation in dibutyryl-cyclic-AMP-differentiated HL-60 cells. In HL-60 promyelocytes, Pam3Cys-Ser-(Lys)4 had no effect on tyrosine phosphorylation, whereas the lipopeptide also induced tyrosine phosphorylation in 1,25-dihydroxyvitamin-D3-differentiated HL-60 cells and in human neutrophils. These results show that lipopeptides are effective stimulators of tyrosine phosphorylation in mature human myeloid cells.