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The regulation of the IgE response by schistosomula-released products (SRP) was studied either in vitro with rat and human cell cultures or in vivo by injection into rats of SRP with an unrelated allergen at primary or secondary immunization. The results obtained in vitro showed that non-dialysable factors present in SRP potentiate the IgE synthesis by rat and human cells. This enhancing effect was supported by molecules with serine protease activities. On the other hand, the inhibition or depletion of SRP in serine proteases induced ii weak synthesis of IgM by rat cells in vitro. The injection of SRP into rats on day 0 with an unrelated allergen led to a potentiation of total IgE production, but an inhibition of specific IgE response. In contrast, a marked elevation of specific IgE response was obtained when SRP was injected upon secondary immunization. Serine proteases of SRP were partly responsible for this potentiative effect. [ABSTRACT FROM AUTHOR]

Background: The effects of a dietary supplementation with the vegetable ω-3 α-linolenic acid (ALA) on cardiovascular homeostasis are unclear. In this context, it would be interesting to assess the effects of camelina oil., Objective: This study aimed to assess the cardiovascular and metabolic effects of camelina oil in hypertensive patients with metabolic syndrome., Methods: In a double-blind, placebo-controlled randomized study, treated essential hypertensive patients with metabolic syndrome received, during 6 mo, either cyclodextrin-complexed camelina oil containing ≈ 1.5 g ALA/d (n = 40) or an isocaloric placebo (n = 41), consisting of the same quantity of cyclodextrins and wheat starch. Anthropometric data, plasma lipids, glycemia, insulinemia, creatininemia, TBARs, high-sensitivity C-reactive protein, and n-3, n-6, and n-9 fatty acids in erythrocyte membranes were measured. Peripheral and central blood pressures, arterial stiffness, carotid intima-media thickness, and brachial artery endothelium-dependent flow-mediated dilatation (FMD) and endothelium-independent dilatation were assessed., Results: Compared with placebo, camelina oil increased ALA (mean ± SD: 0 ± 0.04 compared with 0.08 ± 0.06%, P <0.001), its elongation product EPA (0 ± 0.5 compared with 0.16 ± 0.65%, P <0.05), and the n-9 gondoic acid (GA; 0 ± 0.04 compared with 0.08 ± 0.04%, P <0.001). No between-group difference was observed for cardiovascular parameters. However, changes in FMD were associated with the magnitude of changes in EPA (r = 0.26, P = 0.03). Compared with placebo, camelina oil increased fasting glycemia (-0.2 ± 0.6 compared with 0.3 ± 0.5 mmol/L, P <0.001) and HOMA-IR index (-0.8 ± 2.5 compared with 0.5 ± 0.9, P <0.01), without affecting plasma lipids, or inflammatory and oxidative stress markers. Changes in HOMA-IR index were correlated with the magnitude of changes in GA (r = 0.32, P <0.01). Nutritional intake remained similar between groups., Conclusion: ALA supplementation with camelina oil did not improve vascular function but adversely affected glucose metabolism in hypertensive patients with metabolic syndrome. Whether this adverse effect on insulin sensitivity is related to GA enrichment, remains to be elucidated., (© The Author(s) 2021. Published by Oxford University Press on behalf of the American Society for Nutrition.)

Traffic air pollution is a major health problem and is recognized as an important risk factor for cardiovascular (CV) diseases. In a previous experimental study, we showed that diesel exhaust (DE) exposures induced cardiac mitochondrial and CV dysfunctions associated with the gaseous phase. Here, we hypothesized that NO 2 exposures to levels close to those found in DE induce a mitochondrial reactive oxygen species (ROS) production, which contribute to an endothelial dysfunction, an early indicator for numerous CV diseases. For this, we studied the effects of NO 2 on ROS production and its impacts on the mitochondrial, coronary endothelial and cardiac functions, after acute (one single exposure) and repeated (three h/day, five days/week for three weeks) exposures in Wistar rats. Acute NO 2 exposure induced an early but reversible mitochondrial ROS production. This event was isolated since neither mitochondrial function nor endothelial function were impaired, whereas cardiac function assessment showed a reversible left ventricular dysfunction. Conversely, after three weeks of exposure this alteration was accompanied by a cardiac mitochondrial dysfunction highlighted by an alteration of adenosine triphosphate (ATP) synthesis and oxidative phosphorylation and an increase in mitochondrial ROS production. Moreover, repeated NO 2 exposures promoted endothelial dysfunction of the coronary arteries, as shown by reduced acetylcholine-induced vasodilatation, which was due, at least partially, to a superoxide-dependent decrease of nitric oxide (NO) bioavailability. This study shows that NO 2 exposures impair cardiac mitochondrial function, which, in conjunction with coronary endothelial dysfunction, contributes to cardiac dysfunction. Together, these results clearly identify NO 2 as a probable risk factor in ischemic heart diseases.

Introduction: Imeglimin, a glucose-lowering agent targeting mitochondrial bioenergetics, decreases reactive oxygen species (ROS) overproduction and improves glucose homeostasis. We investigated whether this is associated with protective effects on metabolic syndrome-related left ventricular (LV) and vascular dysfunctions., Methods: We used Zucker fa/fa rats to assess the effects on LV function, LV tissue perfusion, LV oxidative stress and vascular function induced by imeglimin administered orally for 9 or 90 days at a dose of 150 mg/kg twice daily., Results: Compared to untreated animals, 9- and 90-day imeglimin treatment decreased LV end-diastolic pressure and LV end-diastolic pressure-volume relation, increased LV tissue perfusion and decreased LV ROS production. Simultaneously, imeglimin restored acetylcholine-mediated coronary relaxation and mesenteric flow-mediated dilation. One hour after imeglimin administration, when glucose plasma levels were not yet modified, imeglimin reduced LV mitochondrial ROS production and improved LV function. Ninety-day imeglimin treatment reduced related LV and kidney fibrosis and improved kidney function., Conclusion: In a rat model, mimicking Human metabolic syndrome, imeglimin immediately countered metabolic syndrome-related cardiac diastolic and vascular dysfunction by reducing oxidative stress/increased NO bioavailability and improving myocardial perfusion and after 90-day treatment myocardial and kidney structure, effects that are, at least in part, independent from glucose control., Competing Interests: Marianne Lachaux, Matthieu Soulié, Mouad Hamzaoui, Anaëlle Bailly, Lionel Nicol, Isabelle Rémy‐Jouet, Sylvanie Renet, Cathy Vendeville, Christelle Monteil, Vincent Richard and Paul Mulder (being the guarantor) have nothing to declare. Pascale Gluais‐Dagorn and Sophie Hallakou‐Bozec are employee Poxel SA., (© 2020 The Authors. Endocrinology, Diabetes & Metabolism published by John Wiley & Sons Ltd.)

Diesel exhaust (DE) contributes to air pollution, an important risk factor for cardiovascular diseases. However, the mechanisms by which DE exposure induces cardiovascular dysfunction remain unknown and there is still debate on the contribution of the primary particulate matter (PM) fraction compared to the gaseous phase. Although the mitochondria play a key role in the events leading to cardiovascular diseases, their role in DE-induced cardiovascular effects has not been investigated. The aim of this study was to highlight cardiac and mitochondrial events that could be disrupted following acute and/or repeated DE exposures and the contribution of gaseous pollutants to these effects. To address this question, Wistar rats were exposed to DE generated under strictly controlled and characterized conditions and extracted upstream or downstream of the diesel particulate filter (DPF). Evaluation of the cardiac function after acute DE exposure showed a disturbance in echocardiographic parameters, which persisted and worsened after repeated exposures. The presence of the DPF did not modify the cardiovascular dysfunction revealing an important implication of the gas phase in this response. Surprisingly, redox parameters were not altered by DE exposures while an alteration in mitochondrial oxidative capacity was observed. Exploration of the mitochondrial function demonstrated a more specific alteration in complex I of the respiratory chain after repeated exposures, which was further confirmed by transcriptional analysis of left ventricular (LV) tissue. In conclusion, this work provides new insights into cardiovascular effects induced by DE, demonstrating a cardiac mitochondrial impairment associated with the gaseous phase. These effects suggest deleterious consequences in terms of cardiac function for vulnerable populations with underlying energy deficit such as patients with heart failure or the elderly., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

The contribution of diesel exhaust to atmospheric pollution is a major concern for public health, especially in terms of occurrence of lung cancers. The present study aimed at addressing the toxic effects of a repeated exposure to these emissions in an animal study performed under strictly controlled conditions. Rats were repeatedly exposed to the exhaust of diesel engine. Parameters such as the presence of a particle filter or the use of gasoil containing rapeseed methyl ester were investigated. Various biological parameters were monitored in the lungs to assess the toxic and genotoxic effects of the exposure. First, a transcriptomic analysis showed that some pathways related to DNA repair and cell cycle were affected to a limited extent by diesel but even less by biodiesel. In agreement with occurrence of a limited genotoxic stress in the lungs of diesel-exposed animals, small induction of γ-H2AX and acrolein adducts was observed but not of bulky adducts and 8-oxodGuo. Unexpected results were obtained in the study of the effect of the particle filter. Indeed, exhausts collected downstream of the particle filter led to a slightly higher induction of a series of genes than those collected upstream. This result was in agreement with the formation of acrolein adducts and γH2AX. On the contrary, induction of oxidative stress remained very limited since only SOD was found to be induced and only when rats were exposed to biodiesel exhaust collected upstream of the particle filter. Parameters related to telomeres were identical in all groups. In summary, our results point to a limited accumulation of damage in lungs following repeated exposure to diesel exhausts when modern engines and relevant fuels are used. Yet, a few significant effects are still observed, mostly after the particle filter, suggesting a remaining toxicity associated with the gaseous or nano-particular phases., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Objectives: The current study addressed the hypothesis that the local decrease in endothelin-1 (ET-1) bioavailability during sustained flow increases contributes to endothelium-dependent, flow-mediated dilatation (FMD) of conduit arteries and is altered in presence of cardiovascular risk factors., Methods and Results: In nine young healthy individuals, the decrease in local ET-1 plasma levels and radial artery FMD in response to hand skin heating (from 34 to 44 °C) was not affected by endothelin type A (ETA) receptor blockade, achieved using the brachial infusion of BQ-123 (100 nmol/min per l of forearm), as compared with physiological saline (0.9% NaCl) infusion. In contrast, endothelin type B (ETB) receptor blockade with BQ-788 (10 nmol/min per l) suppressed the decrease in plasma ET-1 during heating and reduced FMD, without altering nitric oxide release. The coinfusion of BQ-123 did not affect the inhibitory effect of ETB receptor blockade on the decrease in ET-1 plasma levels during heating but prevented the reduction in FMD. Basal radial artery parameters, systemic hemodynamics, and endothelium-independent dilatation to glyceryl trinitrate were not modified by ETA and/or ETB blockade. In a general population of 40 participants without treatment or major cardiovascular diseases, including the nine healthy individuals, the reduction in endothelin-1 level during heating was correlated with FMD (r = -0.55, P < 0.001) and decreased with increased age (r = 0.49, P = 0.001), mean arterial blood pressure (r = 0.48, P = 0.002), and total cholesterol level (r = 0.37, P = 0.024)., Conclusion: The uptake of endothelin-1 by ETB receptors contributes to conduit artery FMD, preventing its vasoconstrictor action mediated by ETA receptors. The alteration of this mechanism by cardiovascular risk factors may contribute to endothelial dysfunction.

Diesel exhausts are partly responsible for the deleterious effects on human health associated with urban pollution, including cardiovascular diseases, asthma, COPD, and possibly lung cancer. Particulate fraction has been incriminated and thus largely investigated for its genotoxic properties, based on exposure conditions that are, however, not relevant for human risk assessment. In this paper, original and more realistic protocols were used to investigate the hazards induced by exhausts emitted by the combustion of standard (DF0) vs. bio-diesel fuels (DF7 and DF30) and to assess the impact of exhaust treatment devices (DOC and DPF). Mutagenicity and genotoxicity were evaluated for (1) resuspended particles ("off line" exposure that takes into account the bioavailability of adsorbed chemicals) and for (2) the whole aerosols (particles+gas phase components) under continuous flow exposure ("on line" exposure). Native particles displayed mutagenic properties associated with nitroaromatic profiles (YG1041), whereas PAHs did not seem to be involved. After DOC treatment, the mutagenicity of particles was fully abolished. In contrast, the level of particle deposition was low under continuous flow exposure, and the observed mutagenicity in TA98 and TA102 was thus attributable to the gas phase. A bactericidal effect was also observed in TA102 after DOC treatment, and a weak but significant mutagenicity persisted after DPF treatment for bio-diesel fuels. No formation of bulky DNA-adducts was observed on A549 cells exposed to diesel exhaust, even in very drastic conditions (organic extracts corresponding to 500 μg equivalent particule/mL, 48 h exposure). Taken together, these data indicate that the exhausts issued from the bio-diesel fuels supplemented with rapseed methyl ester (RME), and generated by current diesel engines equipped with after treatment devices are less mutagenic than older ones. The residual mutagenicity is linked to the gas phase and could be due to pro-oxydants, mainly for RME-supplemented fuels., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Background: Middle molecular weight uraemic toxins are considered to play an important role in vascular dysfunction and cardiovascular outcomes in end-stage renal disease (ESRD) patients. Recent dialysis techniques based on convection, specifically high-efficiency on-line haemodiafiltration (HDF), enhance the removal of middle molecular weight toxins and reduce all-cause mortality in haemodialysis (HD) patients. However, the mechanisms of these improved outcomes remain to be established., Methods: This prospective study randomly assigned 42 ESRD patients to switch from high-flux HD to high-efficiency on-line HDF (n=22) or to continue HD (n=20). Brachial artery endothelium-dependent flow-mediated dilatation, central pulse pressure, carotid artery intima-media thickness (IMT), internal diastolic diameter and distensibility and circulating markers of uraemia, inflammation and oxidative stress were blindly assessed before and after a 4-month follow-up., Results: Brachial flow-mediated dilatation and carotid artery distensibility increased significantly in the HDF group compared with HD, while carotid IMT and diameter remained similar. HDF decreased predialysis levels of the uraemic toxins β2-microglobulin, phosphate and blood TNFα mRNA expression. Oxidative stress markers were not different between the HD and HDF groups. Blood mRNA expression of protein kinase C β2, an endothelial NO-synthase (eNOS) inhibitor, decreased significantly with HDF., Conclusions: High-efficiency on-line HDF prevents the endothelial dysfunction and stiffening of the conduit arteries in ESRD patients compared with high-flux HD. HDF decreases uraemic toxins, vascular inflammation, and is associated with subsequent improvement in eNOS functionality. These results suggest that reduced endothelial dysfunction may be an intermediate mechanism explaining the beneficial outcomes associated with HDF.

Recent studies have shown that long-term cocaine use induces diastolic impairment and a myocardial oxidative stress. Recently, we have reported that cocaine-induced cardiac dysfunction may be due to a mitochondrial reactive oxygen species (ROS) overproduction, which occurs at the same time as xanthine oxidase (XO) activation. In this work, we hypothesized that XO activation contributes to mitochondrial ROS overproduction, which in turn contributes to diastolic dysfunction. To test this, we used a well-established in vivo model of cocaine-induced diastolic dysfunction. In this experimental model treated with or without allopurinol, an inhibitor of XO, we measured mitochondrial ROS production and function. Mitochondrial alterations were characterized by an increase in oxygen consumption through complexes I and III, a reduction in ATP production, and an increased ROS production specifically in isolated interfibrillar mitochondria. Allopurinol treatment prevented the rise in mitochondrial ROS levels and the decrease in ATP production. In the same way, allopurinol treatment improved ventricular relaxation with a decrease in Tau, an index of left ventricle relaxation and of end-diastolic pressure volume relation. These results confirmed the critical role of XO in the sequence of events leading to cocaine-induced cardiac dysfunction.

Influenza A virus (IAV) infection results in a highly contagious respiratory illness leading to substantial morbidity and occasionally death. In this report, we assessed the in vivo physiological contribution of invariant NKT (iNKT) lymphocytes, a subset of lipid-reactive αβ T lymphocytes, on the host response and viral pathogenesis using a virulent, mouse-adapted, IAV H3N2 strain. Upon infection with a lethal dose of IAV, iNKT cells become activated in the lungs and bronchoalveolar space to become rapidly anergic to further restimulation. Relative to wild-type animals, C57BL/6 mice deficient in iNKT cells (Jα18(-/-) mice) developed a more severe bronchopneumonia and had an accelerated fatal outcome, a phenomenon reversed by the adoptive transfer of NKT cells prior to infection. The enhanced pathology in Jα18(-/-) animals was not associated with either reduced or delayed viral clearance in the lungs or with a defective local NK cell response. In marked contrast, Jα18(-/-) mice displayed a dramatically reduced IAV-specific CD8(+) T cell response in the lungs and in lung-draining mediastinal lymph nodes. We further show that this defective CD8(+) T cell response correlates with an altered accumulation and maturation of pulmonary CD103(+), but not CD11b(high), dendritic cells in the mediastinal lymph nodes. Taken together, these findings point to a role for iNKT cells in the control of pneumonia as well as in the development of the CD8(+) T cell response during the early stage of acute IAV H3N2 infection.

Using a focused glycan-gene microarray, we compared the glycosyltransferase (GT) and sulfotransferase gene expression profiles of human monocytes, dendritic cells (DCs) and macrophages (Mphis), isolated or differentiated from the same donors. Microarray analysis indicated that monocytes express transcripts for a full set of enzymes involved in the biosynthesis of multi-multiantennary branched N-glycans, potentially elongated by poly-N-acetyl-lactosamine chains, and of mucin-type Core 1 and Core 2 sialylated O-glycans. Monocytes also express genes involved in the biosynthesis and modification of glycosaminoglycans, but display a limited expression of GTs implicated in glycolipid synthesis. Among genes expressed in monocytes (90 out of 175), one third is significantly modulated in DCs and Mphi respectively, most of them being increased in both cell types relative to monocytes. These changes might potentially enforce the capacity of differentiated cells to synthesize branched N-glycans and mucin-type O-glycans and to remodel cell surface proteoglycans. Stimulation of DCs and Mphis with lipopolysaccharide caused a general decrease in gene expression, mainly affecting genes found to be positively modulated during the differentiation steps. Interestingly, although a similar set of enzymes are modulated in the same direction in mature DCs and Mphis, cell specific genes are also differentially regulated during maturation, a phenomenon that may sustain functional specificities. Validation of this analysis was provided by quantitative real-time PCR and flow cytometry of cell surface glycan antigens. Collectively, this study implies an important modification of the pattern of glycosylation in DCs and Mphis undergoing differentiation and maturation with potential biological consequences.

Unmethylated CpG oligodeoxynucleotides (ODNs), by activating cells of the innate immune system, such as dendritic cells and NK cells, are potent adjuvants for type 1 immune responses. In the present study, we aimed to investigate the role of invariant NKT (iNKT) cells, a subset of lipid-reactive innate lymphocytes, in CpG ODN-induced innate and acquired type 1 responses. Our data show that, in response to the CpG ODN type B 1826, splenic and hepatic iNKT cells become activated and produce IFN-gamma, but not IL-4, both in vitro and in vivo. This Th1 bias is independent from the Ag-presenting molecule CD1d and strongly requires IL-12, at least in vitro. We also report that iNKT cell activation, in response to CpG ODN type B, results in the transactivation of NK cells. To address the potential role of iNKT cells in type 1 innate immunity induced by CpG ODN, a murine model of malignant melanoma was used. We show that CpG ODN type B protects mice against B16F10-induced lung metastasis in wild-type mice, but in a less efficient manner in iNKT cell-deficient animals. Finally, we report that immunization of wild-type mice with CpG ODN type B plus keyhole limpet hemocyanin biases the immune response toward a Th1 direction, an effect strongly mediated by iNKT cells. We conclude that iNKT cells amplify the innate and acquired response to CpG ODN type B, with potentially important consequences for the regulation of immune responses.

Free Bordetella pertussis filamentous hemagglutinin (FHA) can act as an adjuvant for mucosally administrated antigens. Here, we show that independently of the adjuvant properties of FHA toward an unrelated antigen, total IgG or IgA concentrations in serum and mucosal fluids are enhanced by the administration of FHA. Oral administration of FHA increases both total IgG concentrations in serum and total immunoglobulin concentrations in intestinal lavages. Nasal administration of FHA increases total IgA concentrations in broncho-alveolar lavages. FHA induces Langerhans cell recruitment and MIP-3alpha mRNA expression within hours after administration. These observations shed a new light on the potential molecular mechanisms of FHA-induced adjuvanticity.

Toll-like receptors (TLRs) play an important role in the innate recognition of pathogens by dendritic cells (DCs) and in the induction of immune responses. Few studies have been devoted to address the impact of TLR2 (a fully MyD88-dependent receptor) and TLR3 (a fully TRIF-dependent receptor) co-activation on DC functions, especially in the mouse system. Using canonical agonists, we show that TLR2 acts in concert with TLR3 to induce the synthesis of inflammatory cytokines (TNF-alpha, IL-6), of some IL-12 family members (IL-12p40, IL-12p23, IL-27p28) and of the Notch ligand Delta-4 by mouse DCs. In contrast, TLR2 interferes with the TLR3-induced expression of type I interferon stimulated genes (MIG/CXCL9, IP-10/CXCL10, GARG39) and IL-12p35. We also report that TLR2 cooperates with TLR3 to enhance the DC-mediated production of IFN-gamma by Natural Killer cells and by conventional Ag-specific T lymphocytes. To conclude, our data support the existence of TLR2 and TLR3 synergy and cross-inhibition in DCs that could be important to strengthen immune responses during infection.

CD1d-restricted natural killer T (NKT) cells represent a heterogeneous population of innate memory immune cells expressing both NK and T-cell markers distributed into two major subsets, i.e., invariant NKT (iNKT) cells, which express exclusively an invariant T-cell receptor (TCR) alpha chain (Valpha14Jalpha18 in mice), and non-iNKT cells, which express more diverse TCRs. NKT cells quickly produce Th1- and/or Th2-type cytokines following stimulation with glycolipid antigen (Ag) and, through this property, play potent immunoregulatory roles in autoimmune diseases, cancer, and infection. No study has addressed the role of NKT cells in metazoan parasite infections so far. We show that during murine schistosomiasis, the apparent frequency of both iNKT cells and non-iNKT cells decreased in the spleen as early as 3 weeks postinfection (p.i.) and that both populations expressed a greater amount of the activation marker CD69 at 6 weeks p.i., suggesting an activated phenotype. Two different NKT-cell-deficient mouse models, namely, TCR Jalpha18-/- (exclusively deficient in iNKT cells) and CD1d-/- (deficient in both iNKT and non-iNKT cells) mice, were used to explore the implication of these subsets in infection. We show that whereas both iNKT and non-iNKT cells do not have a major impact on the immune response during the early phase (1 and 4 weeks) of infection, they exert important, although opposite, effects on the immune response during the acute phase of the disease (7 and 12 weeks), after schistosome egg production. Indeed, iNKT cells contribute to Th1 cell differentiation whereas non-iNKT cells might be mostly implicated in Th2 cell differentiation in response to parasite Ag. Our findings suggest, for the first time, that helminths activate both iNKT and non-iNKT cells in vivo, enabling them to differentially influence the Th1/Th2 balance of the immune response.

Objective: Unmethylated cytosine-phosphate-guanine (CpG) oligodeoxynucleotides are highly frequent motifs in bacterial DNA and rare in the mammalian genome. They are potent inducers of inflammatory cytokines and act synergistically with lipopolysaccharide (LPS) for the induction of tumor necrosis factor alpha (TNF-alpha) production in vivo. It has therefore been suggested that innate immune reaction to bacterial unmethylated CpG motifs might contribute to the development of septic shock. We designed this study to assess the sensitization role of CpG motifs in LPS-induced shock using the D-galactosamine (D-GalN)-sensitized mouse model., Design: A prospective, randomized in vivo animal laboratory study., Setting: Experimental research laboratory., Intervention: We performed experiments in which CpG, LPS and D-GalN were administrated sequentially in various orders or simultaneously in 8 week-old BALB/c mice., Measurements and Results: Cytosine-phosphate-guanine treatment potentiated LPS action only if injected prior to LPS. A combination of predefined sublethal doses of CpG (1 nmol/mouse) and LPS (1 ng/mouse) not only had a synergetic effect on TNF-alpha production (20.3+/-9.2 IU/ml versus 2.5+/-1.4 IU/ml and 5.6+/-3.4 IU/ml for CpG and LPS groups, respectively, p<0.05), but also led to animal death (5/5). An CpG effect requires de novo mRNA synthesis, since the sensitizing effect was inhibited by co-administration of mRNA transcription inhibitors such as D-GalN and pentoxifylline, which is a specific TNF-alpha transcription inhibitor. Furthermore, CpG treatment provoked a strong TNF-alpha mRNA production in the liver that was dramatically reduced by pre-treatment with D-GalN., Conclusion: Our findings indicate that CpG motifs act synergistically with LPS by initializing the synthesis of TNF-alpha and/or TNF-alpha regulating factors, thereby acting as a sensitizing agent.

A common property of allergens is their potential to generate type 2 cytokine responses. To understand the mechanisms involved in this phenomenon, we have evaluated the polarizing potential of a major allergen, Dermatophagoides pteronyssinus 1 (Der p 1), in an heterologous immunization system using the glutathione S-transferase of the parasite Schistosoma mansoni (Sm28-GST) as immunogen. In previous studies, we showed that immunization with the Sm28-GST emulsified in CFA induced a nonpolarized immune response. In contrast, when alum was used as adjuvant, a type 2 immune response was induced against Sm28-GST. Using this experimental model, we examined whether the administration of Der p 1 together with Sm28-GST influenced the nonpolarized and/or the Th2 profiles induced by the CFA or the alum immunization, respectively. Our results showed that the introduction of Der p 1 in the CFA immunization protocol was associated with diminished anti-Sm28-GST IgG2a Ab titers, reduced IFN-gamma mRNA expression, and frequency of IFN-gamma-producing cells. In contrast, the introduction of Der p 1 in the alum protocol did not affect IL-4 or Ig isotype responses. The effect of Der p 1 was specific, since coimmunization with tetanus toxin fragment C did not affect the profile of the response against Sm28-GST. Furthermore, inactivation of Der p 1 reduced its ability to modify the immune response profile, suggesting that its protease activity played an important role in deviating the immune response. Our results suggest that the Der p 1 has the ability to modify the profile of an immune response by modulating the balance between the polarizing cytokines IL-4 and IFN-gamma.

It has recently been demonstrated that the Schistosoma mansoni P28 antigen can induce a strong protective immunity after direct immunization in various experimental models. T lymphocytes from Fischer rats immunized with the recombinant P28 antigen were cultured in vitro in the presence of seven synthetic peptides derived from the amino acid sequence of the P28. The most significant and reproducible proliferation was obtained with the 24-43 and 115-131 synthetic peptides. In order to analyze whether these located determinants were also exposed to the host's immune system during the natural S. mansoni infection or after immunization with crude antigenic extracts of various development stages of the parasite, the T-cell responsiveness of infected or immunized Fischer rats and BALB/c mice was tested towards these synthetic peptides. The results showed that, in both permissive (mouse) and non-permissive (rat) hosts, 24-43 and 115-131 synthetic peptides are recognized during the course of infection and that there is a dynamic variation of this recognition. These peptides are also recognized by T cells educated against crude antigenic extracts of different developmental stages of the parasite which contained the native form of the P28 molecule. Taken together, the results indicated that these synthetic peptides derived from the recombinant P28 antigen can activate T lymphocytes educated against the native P28 molecule during the development and maturation of the parasite in their hosts. Therefore, they might be useful for the construction of synthetic vaccines against schistosomiasis.