Akkermansia muciniphila phospholipid induces homeostatic immune responses.

Multiple studies have established associations between human gut bacteria and host physiology, but determining the molecular mechanisms underlying these associations has been challenging1-3. Akkermansia muciniphila has been robustly associated with positive systemic effects on host metabolism, favourable outcomes to checkpoint blockade in cancer immunotherapy and homeostatic immunity4-7. Here we report the identification of a lipid from A. muciniphila's cell membrane that recapitulates the immunomodulatory activity of A. muciniphila in cell-based assays8. The isolated immunogen, a diacyl phosphatidylethanolamine with two branched chains (a15:0-i15:0 PE), was characterized through both spectroscopic analysis and chemical synthesis. The immunogenic activity of a15:0-i15:0 PE has a highly restricted structure-activity relationship, and its immune signalling requires an unexpected toll-like receptor TLR2-TLR1 heterodimer9,10. Certain features of the phospholipid's activity are worth noting: it is significantly less potent than known natural and synthetic TLR2 agonists; it preferentially induces some inflammatory cytokines but not others; and, at low doses (1% of EC50) it resets activation thresholds and responses for immune signalling. Identifying both the molecule and an equipotent synthetic analogue, its non-canonical TLR2-TLR1 signalling pathway, its immunomodulatory selectivity and its low-dose immunoregulatory effects provide a molecular mechanism for a model of A. muciniphila's ability to set immunological tone and its varied roles in health and disease.

MYMD-1, a Novel Immunometabolic Regulator, Ameliorates Autoimmune Thyroiditis via Suppression of Th1 Responses and TNF-α Release.

MYMD-1 is a synthetic derivative of tobacco alkaloids, compounds that possess immunoregulatory properties and have been linked to the epidemiological observation that smoking reduces the odds of developing thyroid Abs and hypothyroidism. To assess the effect and mechanism(s) of the action of MYMD-1, we chose the NOD.H-2h4 mouse model of spontaneous thyroiditis. We began in vitro using T cells isolated from NOD.H-2h4 spleens and found that MYMD-1 suppressed TNF-α production by CD4+ T cells in a dose-dependent manner. We then treated 58 NOD.H-2h4 mice for 12 wk with either unsupplemented water that contained (10 mice) or did not contain (16 mice) MYMD-1 (185 mg/l) or water supplemented with sodium iodide (500 mg/l) that contained (16 mice) or did not contain (16 mice) MYMD-1. Mice were bled at baseline and then every 2 wk until sacrifice. MYMD-1 decreased the incidence and severity (p < 0.001) of thyroiditis, as assessed by histopathology. Similarly, the number of CD3+ T cells and CD19+ B cells infiltrating the thyroid was dampened by MYMD-1, as assessed by flow cytometry. Interestingly, the subset of thyroidal CD3+CD4+Tbet+RORγT- effector Th1 cells and the systemic levels of TNF-α were decreased by MYMD-1. Serum thyroglobulin Abs decreased in the MYMD-1 group. Thyroid hormones did not differ among the four groups, whereas thyroid-stimulating hormone increased upon iodine supplementation but remained normal in MYMD-1-treated mice. Overall, the study suggests that MYMD-1 ameliorates thyroiditis acting on specific lymphoid subsets. Further studies, including other models of autoimmunity, will confirm the potential clinical use of MYMD-1 as a novel immunometabolic regulator.

Aß1-16 can aggregate and induce the production of reactive oxygen species, nitric oxide, and inflammatory cytokines.

Amyloid-ß (Aß40/42) aggregates containing the cross-ß-sheet structure are associated with the pathogenesis of Alzheimer's disease (AD). It is generally accepted that the N-terminal peptide of Aß40/42, Aß1-16, does not aggregate, and is not cytotoxic. However, we here show that Aß1-16 can aggregate, and form cytotoxic aggregates containing ß-turns and regular non-amyloid ß-sheet structures. Factors such as pH, ionic strength, and agitation were found to influence Aß1-16 aggregation, and the amino acid residues Asp1, His6, Ser8, and Val12 in Aß1-16 may play a role in this aggregation. Our MTT results showed that Aß1-16 monomers or oligomers were toxic to SH-SY5Y cells, but Aß1-16 fibrils exhibited less cytotoxicity. Our studies also indicate that Aß1-16 aggregates can increase the formation of reactive oxygen species and nitric oxide, induce the loss of calcium homeostasis, and incur the microglial production of TNF-α and IL-4. Thus, our findings suggest that Aß1-16 may contribute to AD pathogenesis.

EC144, a synthetic inhibitor of heat shock protein 90, blocks innate and adaptive immune responses in models of inflammation and autoimmunity.

Heat shock protein 90 (Hsp90) is a molecular chaperone involved in folding and stabilizing multiple intracellular proteins that have roles in cell activation and proliferation. Many Hsp90 client proteins in tumor cells are mutated or overexpressed oncogenic proteins driving cancer cell growth, leading to the acceptance of Hsp90 as a potential therapeutic target for cancer. Because several signal transduction molecules that are dependent on Hsp90 function are also involved in activation of innate and adaptive cells of the immune system, we investigated the mechanism by which inhibiting Hsp90 leads to therapeutic efficacy in rodent models of inflammation and autoimmunity. EC144, a synthetic Hsp90 inhibitor, blocked LPS-induced TLR4 signaling in RAW 264.7 cells by inhibiting activation of ERK1/2, MEK1/2, JNK, and p38 MAPK but not NF-κB. Ex vivo LPS-stimulated CD11b(+) peritoneal exudate cells from EC144-treated mice were blocked from phosphorylating tumor progression locus 2, MEK1/2, and ERK1/2. Consequently, EC144-treated mice were resistant to LPS administration and had suppressed systemic TNF-α release. Inhibiting Hsp90 also blocked in vitro CD4(+) T cell proliferation in mouse and human MLRs. In vivo, semitherapeutic administration of EC144 blocked disease development in rat collagen-induced arthritis by suppressing the inflammatory response. In a mouse collagen-induced arthritis model, EC144 also suppressed disease development, which correlated with a suppressed Ag-specific Ab response and a block in activation of Ag-specific CD4(+) T cells. Our results describe mechanisms by which blocking Hsp90 function may be applicable to treatment of autoimmune diseases involving inflammation and activation of the adaptive immune response.

CXCL4L1 inhibits angiogenesis and induces undirected endothelial cell migration without affecting endothelial cell proliferation and monocyte recruitment.

BACKGROUND AND OBJECTIVES: The non-allelic variant of CXCL4/PF4, CXCL4L1/PF4alt, differs from CXCL4 in three amino acids of the C-terminal α-helix and has been characterized as a potent anti-angiogenic regulator. Although CXCL4 structurally belongs to the chemokine family, it does not behave like a 'classical' chemokine, lacking significant chemotactic properties. Specific hallmarks are its angiostatic, anti-proliferative activities, and proinflammatory functions, which can be conferred by heteromer-formation with CCL5/RANTES enhancing monocyte recruitment. METHODS AND RESULTS: Here we show that tube formation of endothelial cells was inhibited by CXCL4L1 and CXCL4, while only CXCL4L1 triggered chemokinesis of endothelial cells. The chemotactic response towards VEGF and bFGF was attenuated by both variants and CXCL4L1-induced chemokinesis was blocked by bFGF or VEGF. Endothelial cell proliferation was inhibited by CXCL4 (IC(50) 6.9 µg mL(-1)) but not by CXCL4L1, while both chemokines bound directly to VEGF and bFGF. Moreover, CXCL4 enhanced CCL5-induced monocyte arrest in flow adhesion experiments and monocyte recruitment into the mouse peritoneal cavity in vivo, whereas CXCL4L1 had no effect. CXCL4L1 revealed lower affinity to CCL5 than CXCL4, as quantified by isothermal fluorescence titration. As evidenced by the reduction of the activated partial thromboplastin time, CXCL4L1 showed a tendency towards less heparin-neutralizing activity than CXCL4 (IC(50) 2.45 vs 0.98 µg mL(-1)). CONCLUSIONS: CXCL4L1 may act angiostatically by causing random endothelial cell locomotion, disturbing directed migration towards angiogenic chemokines, serving as a homeostatic chemokine with a moderate structural distinction yet different functional profile from CXCL4.

Improved synthesis of ADAM10 inhibitor GI254023X.

BACKGROUND: The metalloproteinases ADAM10 and ADAM17 are involved in various diseases: neurodegeneration, cancer and inflammation. OBJECTIVE: The inhibition of these proteases is a promising target in the treatment of inflammation and cancer. METHODS AND RESULTS: In this study, we present an improved synthesis of the ADAM10 reference inhibitor GI254023X with a higher overall yield, enhanced detection ability and increased acid stability, providing easier handling. CONCLUSION: This upscaled synthesis, free of diastereomeric intermediates, ensures single-batch identity, thus warranting its reproducibility in further biological investigations.

Natural and synthetic agents targeting inflammation and angiogenesis for chemoprevention of prostate cancer.

Prostate cancer is the most common cancer in men and one of the leading causes of cancer-related deaths in Western countries. The extraordinary biological heterogeneity, the increasing incidence of this disease, and the presence of putative premalignant conditions make prostate cancer a crucial pathology to study and test pharmacological or nutritional chemopreventive strategies. It has been demonstrated that the incidence of prostate cancer is lower in Asian people, and that it increases in Asian men living in Western countries; these data point to a pivotal role of diet in the onset of prostate cancer. A large amount of work has been done in investigating chemopreventive properties of dietary compounds widely used in Asian countries (i.e. soy, soybeans, green tea, fish) in respect of the oxidants- and meat-rich diet typical of Western people, particularly of central and northern Europe. Some dietary products appear promising as chemo-preventive agents for prostate cancer, because they display both anti-oxidant and anti-inflammatory activity - and inflammation is crucial for the aetiology of adeno-carcinoma of the prostate. There is increasing evidence for close correlation between inflammation, the microenvironment and tumour-associated neo-angiogenesis causing the adverse outcomes of prostate cancer. It may thus be useful to develop new strategies to couple the treatment of inflammation-related prostate cancer and the generation of angiopreventive or antiinflammatory molecules to prevent this disease. The search for compounds with few or no adverse effects - particularly cardiovascular - as compared with the agents currently in use is therefore of greatest relevance.

Synthesis and proinflammatory properties of muramyl tripeptides containing lysine and diaminopimelic acid moieties.

The unusual amino acid diaminopimelic acid (DAP) was prepared by cross metathesis of appropriately protected vinyl glycine and allyl glycine derivatives. Catalytic hydrogenation of the cross-coupling product resulted in reduction of the double bond and the removal of protecting groups. The resulting compounds were appropriately protected for the polymer-supported and solution-phase synthesis of muramyl tripeptides 2 and 3, which differ in the amidation of the alpha-carboxylic acids of the isoglutamine and DAP moieties. Muramyl dipeptide (1, MDP), the DAP-containing muramyl tripeptide 3, and the lysine-containing muramyl tripeptides 4 and 5 induced TNF-alpha gene expression without TNF-alpha protein production in a human monocytic cell line. The observed block in translation could be removed by co-incubation with LPS, resulting in an apparent synergistic effect. Compound 2 did not induce TNF-alpha gene expression, neither did it exhibit a synergistic effect with LPS; this indicates that amidation of the alpha-carboxylic acids of the isoglutamine and DAP moieties results in a loss of biological activity. It is proposed that amidation of alpha-carboxylic acids is a strategy that may be used by pathogens to avoid detection by the innate immune system. Furthermore, the pattern recognition receptors Nod1 and Nod2 have been implicated in the possible induction of a synergistic effect of muropeptides with LPS.

A proinflammatory peptide from herpes simplex virus type 2 glycoprotein G affects neutrophil, monocyte, and NK cell functions.

We have identified a synthetic peptide derived from the secreted portion of HSV type 2 glycoprotein G, denoted gG-2p20, which has proinflammatory properties in vitro. The gG-2p20 peptide, corresponding to aa 190-205 of glycoprotein G-2, was a chemoattractant for both monocytes and neutrophils in a dose-dependent fashion, and also induced the release of reactive oxygen from these cells. The receptor mediating the responses was identified as the formyl peptide receptor. The gG-2p20-induced activation of phagocytes had a profound impact on NK cell functions. The reactive oxygen species produced by gG-2p20-activated phagocytes both inhibited NK cell cytotoxicity and accelerated the apoptotic cell death in NK cell-enriched lymphocyte populations. Hence, we have for the first time been able to identify a potential function of the secreted portion of HSV-2 glycoprotein G. We propose that the proinflammatory gG-2p20 peptide identified could contribute to a reduced function and viability of NK cells during HSV-2 infection due to its ability to recruit and activate phagocytic cells.

Identification of a peptide derived from vaccinia virus A52R protein that inhibits cytokine secretion in response to TLR-dependent signaling and reduces in vivo bacterial-induced inflammation.

TLRs recognize and respond to conserved motifs termed pathogen-associated molecular patterns. TLRs are characterized by an extracellular leucine-rich repeat motif and an intracellular Toll/IL-1R domain. Triggering of TLRs by pathogen-associated molecular patterns initiates a series of intracellular signaling events resulting in an inflammatory immune response designed to contain and eliminate the pathogen. Vaccinia virus encodes immunoregulatory proteins, such as A52R, that can effectively inhibit intracellular Toll/IL-1R signaling, resulting in a diminished host immune response and enhancing viral survival. In this study, we report the identification and characterization of a peptide derived from the A52R protein (sequence DIVKLTVYDCI) that, when linked to the nine-arginine cell transduction sequence, effectively inhibits cytokine secretion in response to TLR activation. The peptide had no effect on cytokine secretion resulting from cell activation that was initiated independent of TLR stimulation. Using a mouse model of otitis media with effusion, administration of heat-inactivated Streptococcus pneumoniae into the middle ears of BALB/c mice resulted in a significant inflammatory response that was dramatically reduced with peptide treatment. The identification of this peptide that selectively targets TLR-dependent signaling may have application in the treatment of chronic inflammation initiated by bacterial or viral infections.

Mediadores de inflamación (proteína c reactiva) en el niño con desnutrición proteico-energética y en el niño eutrófico / Inflammation mediators (C reactive protein) in children with proteic-energetic malnutrition and in eutrophic children

Con la finalidad de investigar la síntesis de Proteína C Reactiva (PCR) en niños con diferentes grados de desnutrición y entre desnutridos graves infectados y eutróficos infectados; así como en un grupo control de niños eutróficos, se determinó las concentraciones de esta proteína por el método turbidimétrico en 109 niños venezolanos en edades comprendidas entre 6 meses y 6 años. Los resultados encontrados mostraron que el desnutrido grave infectado aumenta su valor de PCR de manera significativa (80,80 ± 38,39 mg/L) en relación con el no infectado (8,17 ± 3,06 mg/L) (p < 0,001). Igualmente hubo diferencias estadísticamente significativas entre los desnutridos graves infectados y el grupo de eutróficos infectados (p < 0,001) quienes presentaron valores más elevados. En relación con los grupos de desnutridos no infectados se encontró diferencia significativa entre los desnutridos graves con el resto de los grupos y el grupo control eutrófico (p < 0,05), no obstante, sus concentraciones permanecieron dentro del valor normal. Estos resultados permiten concluir que el desnutrido infectado es capaz de sintetizar PCR en respuesta a procesos infecciosos graves pero que difiere significativamente cuando sus valores se comparan con los del eutrófico infectado. Por otra parte el desnutrido libre de infección cualquiera que sea su grado de desnutrición mantiene sus valores de PCR en límites normales

Computational design of variant TNF molecules: a novel methodology for inhibition of proinflammatory cascades.

Site-directed mutagenesis of tumor necrosis factor (TNF) based on prediction of the interaction of specific residues with TNF receptors generated dominant-negative constructs, in which single- or double-amino acid changes result in decreased receptor binding and cellular activation. These dominant-negatives not only provide a novel manner to block the proinflammatory effects of TNF, but also can be used as a tool to examine ligand-receptor interactions and their importance in signaling. Because these TNF mutant molecules are smaller than those used for conventional anti-TNF therapies, such as etanercept or infliximab, they are likely to achieve greater tissue concentrations and may provide enhanced therapeutic effect. However, the immunogenicity, as well as efficacy, of the dominant-negative TNF constructs must be more completely examined.

Inflamación II: mediadores químicos / Inflammation II: Chemical mediators

Los diferentes mediadores químicos presentes en el proceso inflamatorio han sido discutidos en forma separada, pero la realidad es que ellos están íntimamente interrelacionados. Un ejemplo de esto es el papel del factor de Hageman activado que actúa al mismo tiempo sobre el sistema de cininas, de coagulación y el fibrinolítico; lo mismo se puede observar de la síntesis y acción de la citocinas que en algunos casos actúan sinergísticamente y presentan acciones en diferentes células blanco. También es necesario entender que existen mecanismos inactivantes de los diferentes mediadores químicos, los cuales limitan la respuesta inflamatoria. Estos mecanismos en algunos casos son bien entendidos (histaminal), y en otros no han sido dilucidados. Como síntesis, podemos enumerar las siguientes tres acciones principales de los mediadores químicos: 1. Aumento en la permeabilidad vascular: Histamina, anafilatoxinas C3a y C5a, cininas y TAF. 2. Quimiotaxis: Fragmentos del complemento C5a, Leucotrieno B4, PAF y productos bacterianos. 3. Fiebre: IL-1 y TNF, Prostaglandinas. 4. Dolor: Prostaglandinas y Bradicinina. La discusión acerca de los mediadores químicos completa la descripción general sobre el proceso inflamatorio, Aun cuando los cambios hemodinámicos, la permeabilidad y el concurso de los leucocitos han sido descritos secuencialmente, se debe tener en cuenta que como respuesta a los agentes desencadenantes el proceso de la inflamación es concurrente, en donde todos los sistemas se disparan simultáneamente con el fin de controlar el daño local ocasionado a tejidos vascularizados.