Semi- and fully synthetic carbohydrate vaccines against pathogenic bacteria : recent developments

The importance of vaccine-induced protection was repeatedly demonstrated over the last three decades and emphasized during the recent COVID-19 pandemic as the safest and most effective way of preventing infectious diseases. Vaccines have controlled, and in some cases, eradicated global viral and bacterial infections with high efficiency and at a relatively low cost. Carbohydrates form the capsular sugar coat that surrounds the outer surface of human pathogenic bacteria. Specific surface-exposed bacterial carbohydrates serve as potent vaccine targets that broadened our toolbox against bacterial infections. Since first approved for commercial use, antibacterial carbohydrate-based vaccines mostly rely on inherently complex and heterogenous naturally derived polysaccharides, challenging to obtain in a pure, safe, and cost-effective manner. The introduction of synthetic fragments identical with bacterial capsular polysaccharides provided well-defined and homogenous structures that resolved many challenges of purified polysaccharides. The success of semisynthetic glycoconjugate vaccines against bacterial infections, now in different phases of clinical trials, opened up new possibilities and encouraged further development towards fully synthetic antibacterial vaccine solutions. In this mini-review, we describe the recent achievements in semi- and fully synthetic carbohydrate vaccines against a range of human pathogenic bacteria, focusing on preclinical and clinical studies

Protein kinase A inhibition of macrophage maturation is accompanied by an increase in DNA methylation of the colonyâ stimulating factor 1 receptor gene

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134212/1/imm12641.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134212/2/imm12641_am.pd

MicroRNA-21 limits uptake of Listeria monocytogenes by macrophages to reduce the intracellular niche and control infection

MiRNAs are important post-transcriptional regulators of gene expression. MiRNA expression is a crucial part of host responses to bacterial infection, however there is limited knowledge of their impact on the outcome of infections. We investigated the influence of miR-21 on macrophage responses during infection with Listeria monocytogenes, which establishes an intracellular niche within macrophages. MiR-21 is induced following infection of bone marrow-derived macrophages (BMDMs) with Listeria. MiR-21-/- macrophages display an increased bacterial burden with Listeria at 30 min and 2 h post-infection. This phenotype was reversed by the addition of synthetic miR-21 mimics to the system. To assess the immune response of wildtype (WT) and miR-21-/- macrophages, BMDMs were treated with bacterial LPS or infected with Listeria. There was no difference in IL-10 and IL-6 between WT and miR-21-/- BMDMs in response to LPS or Listeria. TNF-α was increased in miR-21-/- BMDMs stimulated with LPS or Listeria compared to WT macrophages. We next assessed the production of nitric oxide (NO), a key bactericidal factor in Listeria infection. There was no significant difference in NO production between WT and miR-21-/- cells, indicating that the increased bacterial burden may not be due to impaired killing. As the increased bacterial load was observed early following infection (30 min), we questioned whether this is due to differences in uptake of Listeria by WT and miR-21-/- macrophages. We show that miR-21-deficiency enhances uptake of FITC-dextran and FITC-Escherichia coli bioparticles by macrophages. The previously observed Listeria burden phenotype was ablated by pre-treatment of cells with the actin polymerization inhibitor cytochalasin-D. From analysis of miR-21 targets, we selected the pro-phagocytic regulators myristoylated alanine-rich C-kinase substrate (MARCKS) and Ras homolog gene family, member B (RhoB) for further investigation. MARCKS and RhoB are increased in miR-21-/- BMDMs, correlating with increased uptake of Listeria. Finally, intra-peritoneal infection of mice with Listeria led to increased bacterial burden in livers of miR-21-/- mice compared to WT mice. These findings suggest a possible role for miR-21 in regulation of phagocytosis during infection, potentially by repression of MARCKS and RhoB, thus serving to limit the availability of the intracellular niche of pathogens like L. monocytogenes

Impaired Production and Diurnal Regulation of Vascular RvDn-3 DPA Increase Systemic Inflammation and Cardiovascular Disease.

RATIONALE: Diurnal mechanisms are central to regulating host responses. Recent studies uncovered a novel family of mediators termed as specialized proresolving mediators that terminate inflammation without interfering with the immune response. OBJECTIVE: Herein, we investigated the diurnal regulation of specialized proresolving mediators in humans and their role in controlling peripheral blood leukocyte and platelet activation. METHODS AND RESULTS: Using lipid mediator profiling and healthy volunteers, we found that plasma concentrations of n-3 docosapentaenoic acid-derived D-series resolvins (RvDn-3 DPA) were regulated in a diurnal manner. The production and regulation of these mediators was markedly altered in patients at risk of myocardial infarct. These changes were associated with decreased 5-lipoxygenase expression and activity, as well as increased systemic adenosine concentrations. We also found a significant negative correlation between plasma RvDn-3 DPA and markers of platelet, monocyte, and neutrophil activation, including CD63 and CD11b. Incubation of RvDn-3 DPA with peripheral blood from healthy volunteers and patients with cardiovascular disease significantly and dose-dependently decreased platelet and leukocyte activation. Furthermore, administration of RvD5n-3 DPA to ApoE-/- (apolipoprotein E deficient) mice significantly reduced platelet-leukocyte aggregates, vascular thromboxane B2 concentrations, and aortic lesions. CONCLUSIONS: These results demonstrate that peripheral blood RvDn-3 DPA are diurnally regulated in humans, and dysregulation in the production of these mediators may lead to cardiovascular disease.Sir Henry Dale Fellowship jointly funded by the Wellcome Trust and the Royal Society (grant number: 107613/Z/15/Z),European Research Council under the European Union’s Horizon 2020 research and innovation program (grant number: 677542),Barts Charity (grant number: MGU0343Medical Research Council Advance Course Masters (grant number: MR/J015741/1)Science Foundation Ireland Starting Investigator Research Grant 13/SIRG/2130Wellcome Trust grant 101604/Z/13/

Impaired Production and Diurnal Regulation of Vascular RvDn-3 DPA Increase Systemic Inflammation and Cardiovascular Disease.

RATIONALE: Diurnal mechanisms are central to regulating host responses. Recent studies uncovered a novel family of mediators termed as specialized proresolving mediators that terminate inflammation without interfering with the immune response. OBJECTIVE: Herein, we investigated the diurnal regulation of specialized proresolving mediators in humans and their role in controlling peripheral blood leukocyte and platelet activation. METHODS AND RESULTS: Using lipid mediator profiling and healthy volunteers, we found that plasma concentrations of n-3 docosapentaenoic acid-derived D-series resolvins (RvDn-3 DPA) were regulated in a diurnal manner. The production and regulation of these mediators was markedly altered in patients at risk of myocardial infarct. These changes were associated with decreased 5-lipoxygenase expression and activity, as well as increased systemic adenosine concentrations. We also found a significant negative correlation between plasma RvDn-3 DPA and markers of platelet, monocyte, and neutrophil activation, including CD63 and CD11b. Incubation of RvDn-3 DPA with peripheral blood from healthy volunteers and patients with cardiovascular disease significantly and dose-dependently decreased platelet and leukocyte activation. Furthermore, administration of RvD5n-3 DPA to ApoE-/- (apolipoprotein E deficient) mice significantly reduced platelet-leukocyte aggregates, vascular thromboxane B2 concentrations, and aortic lesions. CONCLUSIONS: These results demonstrate that peripheral blood RvDn-3 DPA are diurnally regulated in humans, and dysregulation in the production of these mediators may lead to cardiovascular disease.Sir Henry Dale Fellowship jointly funded by the Wellcome Trust and the Royal Society (grant number: 107613/Z/15/Z),European Research Council under the European Union’s Horizon 2020 research and innovation program (grant number: 677542),Barts Charity (grant number: MGU0343Medical Research Council Advance Course Masters (grant number: MR/J015741/1)Science Foundation Ireland Starting Investigator Research Grant 13/SIRG/2130Wellcome Trust grant 101604/Z/13/

Transcriptome profiling of primary murine monocytes, lung macrophages and lung dendritic cells reveals a distinct expression of genes involved in cell trafficking

Abstract Background Peripheral blood monocytes (PBMo) originate from the bone marrow, circulate in the blood and emigrate into various organs where they differentiate into tissue resident cellular phenotypes of the mononuclear phagocyte system, including macrophages (Mϕ) and dendritic cells (DC). Like in other organs, this emigration and differentiation process is essential to replenish the mononuclear phagocyte pool in the lung under both inflammatory and non-inflammatory steady-state conditions. While many studies have addressed inflammation-driven monocyte trafficking to the lung, the emigration and pulmonary differentiation of PBMo under non-inflammatory conditions is much less understood. Methods In order to assess the transcriptional profile of circulating and lung resident mononuclear phagocyte phenotypes, PBMo, lung Mϕ and lung DC from naïve mice were flow-sorted to high purity, and their gene expression was compared by DNA microarrays on a genome-wide scale. Differential regulation of selected genes was validated by quantitative PCR and on protein level by flow cytometry. Results Differentially-expressed genes related to cell traffic were selected and grouped into the clusters (i) matrix metallopeptidases, (ii) chemokines/chemokine receptors, and (iii) integrins. Expression profiles of clustered genes were further assessed at the mRNA and protein levels in subsets of circulating PBMo (GR1- vs GR1+) and lung resident macrophages (alveolar vs interstitial Mϕ). Our data identify differentially activated genetic programs in circulating monocytes and their lung descendents. Lung DC activate an extremely diverse set of gene families but largely preserve a mobile cell profile with high expression levels of integrin and chemokine/chemokine receptors. In contrast, interstitial and even more pronounced alveolar Mϕ, stepwise downregulate gene expression of these traffic relevant communication molecules, but strongly upregulate a distinct set of matrix metallopetidases potentially involved in tissue invasion and remodeling. Conclusion Our data provide new insight in the changes of the genetic profiles of PBMo and their lung descendents, namely DC and Mϕ under non-inflammatory, steady-state conditions. These findings will help to better understand the complex relations within the mononuclear phagocyte pool of the lung.</p

Pyruvate Kinase M2 Is Required for the Expression of the Immune Checkpoint PD-L1 in Immune Cells and Tumors

Blocking interaction of the immune checkpoint receptor PD-1 with its ligand PD-L1 is associated with good clinical outcomes in a broad variety of malignancies. High levels of PD-L1 promote tumor growth by restraining CD8+ T-cell responses against tumors. Limiting PD-L1 expression and function is therefore critical for allowing the development of antitumor immune responses and effective tumor clearance. Pyruvate kinase isoform M2 (PKM2) is also a key player in regulating cancer as well as immune responses. PKM2 catalyzes the final rate-limiting step of glycolysis. Furthermore, PKM2 as a dimer translocates to the nucleus, where it stimulates hypoxia-inducible factor 1α (Hif-1α) transactivation domain function and recruitment of p300 to the hypoxia response elements (HRE) of Hif-1α target genes. Here, we provide the first evidence of a role for PKM2 in regulating the expression of PD-L1 on macrophages, dendritic cells (DCs), T cells, and tumor cells. LPS-induced expression of PD-L1 in primary macrophages was inhibited by the PKM2 targeting compound TEPP-46. Furthermore, RNA silencing of PKM2 inhibited LPS-induced PD-L1 expression. This regulation occurs through direct binding of PKM2 and Hif-1α to HRE sites on the PD-L1 promoter. Moreover, TEPP-46 inhibited expression of PD-L1 on macrophages, DCs, and T cells as well as tumor cells in a mouse CT26 cancer model. These findings broaden our understanding of how PKM2 may contribute to tumor progression and may explain the upregulation of PD-L1 in the tumor microenvironment

Dimethyl fumarate and 4-octyl itaconate are anticoagulants that suppress Tissue Factor in macrophages via inhibition of Type I Interferon

Abstract Excessive inflammation-associated coagulation is a feature of infectious diseases, occurring in such conditions as bacterial sepsis and COVID-19. It can lead to disseminated intravascular coagulation, one of the leading causes of mortality worldwide. Recently, type I interferon (IFN) signaling has been shown to be required for tissue factor (TF; gene name F3) release from macrophages, a critical initiator of coagulation, providing an important mechanistic link between innate immunity and coagulation. The mechanism of release involves type I IFN-induced caspase-11 which promotes macrophage pyroptosis. Here we find that F3 is a type I IFN-stimulated gene. Furthermore, F3 induction by lipopolysaccharide (LPS) is inhibited by the anti-inflammatory agents dimethyl fumarate (DMF) and 4-octyl itaconate (4-OI). Mechanistically, inhibition of F3 by DMF and 4-OI involves suppression of Ifnb1 expression. Additionally, they block type I IFN- and caspase-11-mediated macrophage pyroptosis, and subsequent TF release. Thereby, DMF and 4-OI inhibit TF-dependent thrombin generation. In vivo, DMF and 4-OI suppress TF-dependent thrombin generation, pulmonary thromboinflammation, and lethality induced by LPS, E. coli, and S. aureus, with 4-OI additionally attenuating inflammation-associated coagulation in a model of SARS-CoV-2 infection. Our results identify the clinically approved drug DMF and the pre-clinical tool compound 4-OI as anticoagulants that inhibit TF-mediated coagulopathy via inhibition of the macrophage type I IFN-TF axis