Src Kinases Are Required for a Balanced Production of IL-12/IL-23 in Human Dendritic Cells Activated by Toll-Like Receptor Agonists

BACKGROUND: Pathogen recognition by dendritic cells (DC) is crucial for the initiation of both innate and adaptive immune responses. Activation of Toll-like Receptors (TLRs) by microbial molecular patterns leads to the maturation of DC, which present the antigen and activate T cells in secondary lymphoid tissues. Cytokine production by DC is critical for shaping the adaptive immune response by regulating T helper cell differentiation. It was previously shown by our group that Src kinases play a key role in cytokines production during TLR4 activation in human DC. PRINCIPAL FINDINGS: In this work we investigated the role of Src kinases during different TLRs triggering in human monocyte-derived DC (MoDC). We found that Src family kinases are important for a balanced production of inflammatory cytokines by human MoDC upon stimulation of TLR3 and 8 with their respective agonists. Disruption of this equilibrium through pharmacological inhibition of Src kinases alters the DC maturation pattern. In particular, while expression of IL-12 and other inflammatory cytokines depend on Src kinases, the induction of IL-23 and co-stimulatory molecules do not. Accordingly, DC treated with Src inhibitors are not compromised in their ability to induce CD4 T cell proliferation and to promote the Th17 subset survival but are less efficient in inducing Th1 differentiation. CONCLUSIONS: We suggest that the pharmacological modulation of DC maturation has the potential to shape the quality of the adaptive immune response and could be exploited for the treatment of inflammation-related diseases

Development and Application of a Novel SPE-Method for Bioassay-Guided Fractionation of Marine Extracts

The biological diversity of marine habitats is a unique source of chemical compounds with potential use as pharmaceuticals, cosmetics and dietary supplements. However, biological screening and chemical analysis of marine extracts pose specific technical constraints and require adequate sample preparation. Here we report an improved method on Solid Phase Extraction (SPE) to fractionate organic extracts containing high concentration of salt that hampers the recovery of secondary metabolites. The procedure uses a water suspension to load the extracts on a poly(styrene-divynylbenzene)-based support and a stepwise organic solvent elution to effectively desalt and fractionate the organic components. The novel protocol has been tested on MeOH-soluble material from three model organisms (Reniera sarai, Dendrilla membranosa and Amphidinium carterae) and was validated on a small panel of 47 marine samples, including sponges and protists, within discovery programs for identification of immuno-stimulatory and anti-infective natural products

Development and Application of a Novel SPE-Method for Bioassay-Guided Fractionation of Marine Extracts

The biological diversity of marine habitats is a unique source of chemical compounds with potential use as pharmaceuticals, cosmetics and dietary supplements. However, biological screening and chemical analysis of marine extracts pose specific technical constraints and require adequate sample preparation. Here we report an improved method on Solid Phase Extraction (SPE) to fractionate organic extracts containing high concentration of salt that hampers the recovery of secondary metabolites. The procedure uses a water suspension to load the extracts on a poly(styrene-divynylbenzene)-based support and a stepwise organic solvent elution to effectively desalt and fractionate the organic components. The novel protocol has been tested on MeOH-soluble material from three model organisms (Reniera sarai, Dendrilla membranosa and Amphidinium carterae) and was validated on a small panel of 47 marine samples, including sponges and protists, within discovery programs for identification of immuno-stimulatory and anti-infective natural products

Modulation of endotoxicity of Shigella Generalized Modules for Membrane Antigens (GMMA) by genetic lipid A modifications: relative activation of TLR4 and TLR2 pathways in different mutants

Outer membrane particles from Gram-negative bacteria are attractive vaccine candidates as they present surface antigens in their natural environment and orientation. We previously developed a high yield production process for genetically derived particles, called Generalized Modules for Membrane Antigens (GMMA), from Shigella. As GMMA are derived from the outer membrane and contain immune-stimulatory components, especially lipopolysaccharide (LPS), we examined ways of reducing their reactogenicity by modifying lipid A, the endotoxic part of LPS, through deletion of late acyltransferase genes msbB or htrB in GMMA-producing S. sonnei and S. flexneri strains. GMMA with resulting penta-acylated lipid A from the msbB mutants showed a 600-fold reduction, GMMA from the S. sonnei ΔhtrB mutant a 60,000-fold reduced ability compared to GMMA with wild-type lipid A to stimulated human Toll-like receptor 4 (TLR4) in a reporter cell line. In contrast, in the S. flexneri ΔhtrB mutant, a compensatory palmitoleoylation occurs resulting in hexa-acylated lipid A with approximately 10-fold higher activity than the penta-acylated lipid A. In human PBMC, GMMA with penta-acylated lipid A showed a marked reduction in induction of inflammatory cytokines (800-fold for S. sonnei ΔhtrB, 300-fold for the msbB mutants) compared to a 50-fold reduction observed for GMMA with palmitoleoylated lipid A from the S. flexneri ΔhtrB strain. We demonstrated that the residual activity of GMMA with penta-acylated lipid A is largely due to non-lipid A related TLR2 activation whereas GMMA with palmitoleoylated hexa-acylated lipid A predominantly activate TLR4. These results identify the relative activation of TLR4 and TLR2 pathways by GMMA

Systems analysis of human responses to an aluminium hydroxide-adsorbed TLR7 agonist (AS37) adjuvanted vaccine reveals a dose-dependent and specific activation of the interferon-mediated antiviral response

The candidate Adjuvant System AS37 contains a synthetic toll-like receptor agonist (TLR7a) adsorbed to alum. In a phase I study (NCT02639351), healthy adults were randomised to receive one dose of licensed alum-adjuvanted meningococcal serogroup C (MenC-CRM197) conjugate vaccine (control) or MenC-CRM197conjugate vaccine adjuvanted with AS37 (TLR7a dose 12.5, 25, 50 or 100 µg). A subset of 66 participants consented to characterisation of peripheral whole blood transcriptomic responses, systemic cytokine/chemokine responses and multiple myeloid and lymphoid cell responses as exploratory study endpoints. Blood samples were collected pre-vaccination, 6 and 24 h post-vaccination, and 3, 7, 28 and 180 days post-vaccination. The gene expression profile in whole blood showed an early, AS37-specific transcriptome response that peaked at 24 h, increased with TLR7a dose up to 50 µg and generally resolved within one week. Five clusters of differentially expressed genes were identified, including those involved in the interferon-mediated antiviral response. Evaluation of 30 cytokines/chemokines by multiplex assay showed an increased level of interferon-induced chemokine CXCL10 (IP-10) at 24 h and 3 days post-vaccination in the AS37-adjuvanted vaccine groups. Increases in activated plasmacytoid dendritic cells (pDC) and intermediate monocytes were detected 3 days post-vaccination in the AS37-adjuvanted vaccine groups. T follicular helper (Tfh) cells increased 7 days post-vaccination and were maintained at 28 days post-vaccination, particularly in the AS37-adjuvanted vaccine groups. Moreover, most of the subjects that received vaccine containing 25, 50 and 100 µg TLR7a showed an increased MenC-specific memory B cell responses versus baseline. These data show that the adsorption of TLR7a to alum promotes an immune signature consistent with TLR7 engagement, with up-regulation of interferon-inducible genes, cytokines and frequency of activated pDC, intermediate monocytes, MenC-specific memory B cells and Tfh cells. TLR7a 25-50 µg can be considered the optimal dose for AS37, particularly for the adjuvanted MenC-CRM197conjugate vaccine