Sphingosine-1-Phosphate Shapes Healthy Monocytes into An Immunosuppressive Phenotype.

BACKGROUND/AIMS: The physiological phenotype of individuals can influence and shape real-life phenomena in that it can contribute to the development of specific characteristics that can affect the immune response to specific stimuli. In this study we aimed to understand whether the sphingosine/sphingosine-1-phoshate (S1P) axis can modulate the immunotype of circulating cells. METHODS: To pursue this goal, we performed bioinformatic analyses of public datasets. RESULTS: The transcriptomic profile of healthy subjects of GSE192829 dataset identified two clusters with different transcriptional repertoire. Cluster 1 expressed higher levels of enzymes for S1P formation than cluster 0 which was characterized by enzymes that lead to ceramide formation, which represent the opposite metabolic direction. Inference analysis showed that cluster 1 was higher populated by monocytes, CD4+ T and B cells than cluster 0. Of particular interest was the phenotype of the monocytes in cluster 1 which showed an immunosuppressive nature compared to those in cluster 0. The role of S1P signature in healthy PBMCs was confirmed with other dataset analyses, supporting that circulating monocytes positive to the ceramidase, unlike the negative ones, had an immunosuppressive phenotype characterized by hub immunosuppressive markers (i.e. TYROBP, FCER1G, SYK, SIRPA, CSF1R, AIF1, FCGR2A, CLEC7A, LYN, PLCG2, LILRs, HCK, GAB2). This hub genes well discriminated the immunotype of healthy subjects. CONCLUSION: In conclusion this study highlights that S1P-associated hub markers can be useful to discriminate subjects with pronounced immunosuppression.

Sex Differences in Sphingosine-1-Phosphate Levels Are Dependent on Ceramide Synthase 1 and Ceramidase in Lung Physiology and Tumor Conditions.

Sex is a biological variable that can reflect clinical outcomes in terms of quality of life, therapy effectiveness, responsiveness and/or toxicity. Sphingosine-1-phosphate (S1P) is a lipidic mediator whose activity can be influenced by sex. To evaluate whether the S1P axis underlies sex 'instructions' in the lung during physiological and oncological lung conditions, sphingosine and S1P were quantified in the blood of healthy (H) volunteers, lung adenocarcinoma (ADK) and squamous cell carcinoma (SCC) patients of both sexes. S1P receptors and their metabolic enzymes were evaluated in the tissues. Circulating levels of S1P were similar among H female and male subjects and female SCC patients. Instead, male and female ADK patients had lower circulating S1P levels. S1P receptor 3 (S1PR3) was physiologically expressed in the lung, but it was overexpressed in male SCC, and female and male ADK, but not in female SCC patients, who showed a significantly reduced ceramide synthase 1 (CERS1) mRNA and an overexpression of the ceramidase (ASAH1) precursor in lung tumor tissues, compared to male SCC and both male and female ADK patients. These findings highlighted sex differences in S1P rheostat in pathological conditions, but not in physiological conditions, identifying S1P as a prognostic mediator depending on lung cancer histotype.

Induction of Inflammation Disrupts the Negative Interplay between STING and S1P Axis That Is Observed during Physiological Conditions in the Lung.

The stimulator of interferon genes (STING) is a master regulator of innate immunity, involved in several inflammatory diseases. Our previous data showed that sphingosine-1-phosphate (S1P) is released during inflammatory conditions in the lung. The aim of this study was to understand the interplay between S1P and STING during both physiological and pathological conditions. The mRNA levels of ceramidase (ASAH1), S1P precursor enzyme, and STING were inversely correlated in healthy lung tissues, but positively correlated in tumor tissues. The activation of STING induced higher expression of ASAH1 and was accompanied by IFN-ß and IL-6 release. ASAH1 and sphingosine kinases (SPHK I/II) blockade significantly reduced IL-6, but not IFNß, after STING activation. In support of this, taking advantage of a mouse model, we found that inflamed lungs had higher levels of inactive ASAH1 when STING was inhibited. This confirmed the human data, where higher levels of STING promoted the activation of ASAH1. Lung cancer patients positive to STING and ASAH1 mRNA levels had a dismal prognosis in that the overall survival was reduced compared to STING/ASAH1 negative patients. These data highlight that during physiological conditions, STING and the S1P axis do not interfere, whereas in lung cancer patients their interplay is associated to poor prognosis.

Sphingosine-1-Phosphate Contributes to TLR9-Induced TNF-α Release in Lung Tumor Cells.

BACKGROUND/AIMS: Sphingosine-1-phosphate (S1P) is a membrane-derived bioactive phospholipid involved in many lung physiological and pathological processes. Higher levels of S1P have been registered in a broad range of respiratory diseases, including inflammatory disorders and cancer. The aim of our study was to understand the role of S1P in healthy versus tumor cells after Toll-Like Receptors (TLRs) activation, well-known modulators of sphingolipid metabolism. METHODS: Lung adenocarcinoma cells and non-pathological human fibroblasts were stimulated with unmethylated Cytosine phosphate Guanosine (CpG), the TLR9 ligand, and S1P-dependent TNF-α release was evaluated by means of ELISA. Immunofluorescence and LC-MS/MS analysis were performed to evaluate/quantify S1P generation following TLR9 activation. RESULTS: We found that S1P was involved in TLR9-induced TNF-α release in that the inhibition of both ceramidase and sphingosine kinase I/II (SPHK I/II) significantly reduced the levels of TNF-α after TLR9 triggering in lung adenocarcinoma cells. These results were not observed in healthy fibroblasts, implying that this pathway was mainly involved in pathological conditions. Moreover, the activation of TLR4 by means of LPS did not have similar effects as in the case of CpG-stimulated TLR9. Importantly, the activation of TLR9 induced S1P generation and allowed it to interact on the outside membrane receptor S1P1 and S1P3 via the efflux through its membrane transporter SPNS2. Indeed, both the blockade of S1P3 and the transporter SPNS2 significantly reduced the activity of S1P on TNF-α release from lung adenocarcinoma cells. CONCLUSION: Our study identifies a novel inflammatory pathway in that TLR9 increases the pro-inflammatory cytokine release, such as TNF-α, via the induction of a ceramide/S1P imbalance in favor of S1P, adding a novel puzzle piece in TLR9-orchestrated inflammatory pathway and shedding more light on the role of the higher levels of S1P during inflammatory conditions.

Intracellular Sphingosine-1-Phosphate Receptor 3 Contributes to Lung Tumor Cell Proliferation.

BACKGROUND/AIMS: The pleiotropic lipid mediator sphingosine-1-phosphate (S1P) exerts a multitude of effects on respiratory cell physiology and pathology through five S1P receptors (S1PR1-5). Epidemiological studies proved high levels of circulating S1P in non-small cell lung cancer (NSCLC) patients. Studies in literature suggest that high levels of S1P support carcinogenesis but the exact mechanism is still elusive. The aim of this study was to understand the mechanism/s underlying S1P-mediated lung tumor cell proliferation. METHODS: We used human samples of NSCLC, a mouse model of first-hand smoking and of Benzo(a)pyrene (BaP)-induced tumor-bearing mice and A549 lung adenocarcinoma cells. RESULTS: We found that the expression of S1PR3 was also into the nucleus of lung cells in vitro, data that were confirmed in lung tissues of NSCLC patients, smoking and tumor bearing BaP-exposed mice. The intranuclear, but not the membrane, localization of S1PR3 was associated to S1P-mediated proliferation of lung adenocarcinoma cells. Indeed, the inhibition of the membrane S1PR3 did not alter tumor cell proliferation after Toll Like Receptor (TLR) 9 activation. Instead, according to the nuclear localization of sphingosine kinase (SPHK) II, the inhibition of the kinase completely blocked the endogenous S1P-induced tumor cell proliferation. CONCLUSION: These results prove that the nuclear S1PR3/SPHK II axis is involved in lung tumor cell proliferation, highlighting a novel molecular mechanism which could provide differential therapeutic approaches especially in non-responsive lung cancer patients.

Frequency of circulating CD8+CD73+T cells is associated with survival in nivolumab-treated melanoma patients.

BACKGROUND: PD-1 blocking agents, such as nivolumab, have demonstrated clear anti-tumor effects and clinical benefits in a subset of patients with advanced malignancies. Nonetheless, more efforts are needed to identify reliable biomarkers for outcome, to correctly select patients who will benefit from anti-PD-1 treatment. The aim of this study was to investigate the role of peripheral CD8+T cells expressing CD73, involved in the generation of the immune suppressive molecule adenosine, in predicting outcome after nivolumab treatment in advanced melanoma patients. METHODS: PBMCs from 100 melanoma patients treated with nivolumab were collected at National Cancer Institute "G. Pascale" of Naples. Frequencies of CD8+ lymphocytes phenotypes were assessed by flow cytometry at baseline before nivolumab treatment, along with clinical characteristics and blood count parameters. Healthy controls (n = 20) were also analysed. Percentages of baseline T cells expressing PD-1 and CD73 were correlated with outcome after nivolumab treatment. RESULTS: Melanoma patients presented a lower frequency of total circulating CD8+ lymphocytes than control subjects (p = 0.008). Patients with low baseline percentage of circulating CD8+PD-1+CD73+ lymphocytes (< 2.3%) had better survival (22.4 months vs 6.9 months, p = 0.001). Patients (39%) with clinical benefit from nivolumab therapy presented a significantly lower frequency of circulating CD8+PD-1+CD73+ lymphocytes than patients who progressed to nivolumab treatment (p = 0.02). CONCLUSIONS: Our observations suggest that baseline CD73 expression on circulating CD8+PD-1+ lymphocytes appear a promising biomarker of response to anti-PD-1 treatment in melanoma patients. Further investigations are needed for validation and for clarifying its role as prognostic or predictive marker.

Winnie-APCMin/+ Mice: A Spontaneous Model of Colitis-Associated Colorectal Cancer Combining Genetics and Inflammation.

(1) Background: Colorectal cancer (CRC) is among the best examples of the relationship between inflammation and increased cancer risk. (2) Methods: To examine the effects of spontaneous low-grade chronic inflammation on the pathogenesis of CRC, we developed a new murine model of colitis-associated cancer (CAC) by crossing Mucin 2 mutated mice (Winnie) with ApcMin/+ mice. (3) Results: The resulting Winnie-ApcMin/+ model combines an inflammatory background with a genetic predisposition to small intestinal polyposis. Winnie-ApcMin/+ mice show an early occurrence of inflammatory signs and dysplastic lesions in the distal colon with a specific molecular signature. (4) Conclusion: The Winnie-ApcMin/+ model is a perfect model to demonstrate that chronic inflammation represents a crucial risk factor for the onset and progression of tumoral lesions in individuals genetically predisposed to CRC.

Zinc and Calcium Cations Combination in the Production of Floating Alginate Beads as Prednisolone Delivery Systems.

The aim of this research was to verify the application of alginate in combination with Ca2+ and Zn2+ ions to produce a floating and prolonged release system for the oral administration of prednisolone. Hollow and floating gel-beads were designed using prilling/ionotropic gelation as the microencapsulation technique, zinc acetate in the gelling solution as the alginate external crosslinker, and calcium carbonate in the feed as the internal crosslinking agent able to generate gas when in contact with the acidic zinc acetate solution. To achieve this goal, drug/alginate solutions were opportunely combined with different amounts of calcium carbonate. The effect of the addition of calcium carbonate into the feed solution on buoyancy, encapsulation efficiency, morphology, size distribution, as well as in vitro drug release profile of the alginate particles was studied. Moreover, the ability of the floating beads to modulate in vivo the anti-inflammatory response was assayed using the carrageenan-induced acute oedema in rat paw. The proposed strategy allowed obtaining alginate beads with extremely high encapsulation efficiency values (up to 94%) and a very porous inner matrix conferring buoyancy in vitro in simulated gastric fluid up to 5 h. Moreover, in vivo, the best formulation, F4, resulted in the ability to prolong the anti-inflammatory effect up to 15 h compared with raw prednisolone.

Mitochondria and Cardiovascular Disease: A Brief Account.

Mitochondria represent the heart unit of the cardiac cell because they are involved in ATP production and in the transfer to the contractile apparatus. Furthermore, mitochondria modulate Ca2+ homeostasis, manage redox status, and regulate response to cellular and environmental stresses. Abnormalities in mitochondrial organelle structure and function have been observed in many cardiovascular diseases, such as ischemic cardiomyopathy, heart failure, and stroke, and in drug-induced cardiomyopathies. This review summarizes the recent literature in this field.

Leukotriene-mediated sex dimorphism in murine asthma-like features during allergen sensitization.

The incidence and severity of asthma preponderate in women versus men. Leukotrienes (LTs) are lipid mediators involved in asthma pathogenesis, and sex disparities in LT biosynthesis and anti-LT pharmacology in inflammation have recently emerged. Here, we report on sex dimorphism in LT production during allergen sensitization and its correlation to lung function. While high plasma levels of IgE, as sensitization index, were elevated in both sexes, LT levels increased only in lungs of female ovalbumin-sensitized BALB/c mice. Sex-dependent elevated LT levels strictly correlated to an enhanced airway hyperreactivity, pulmonary inflammation and mast cell infiltration/activation in female mice. Importantly, this sex bias was coupled to superior therapeutic efficacy of different types of clinically used LT modifiers like zileuton, MK886 and montelukast in female animals. Our findings reveal sex-dependent LT production as a basic mechanism of sex dimorphism in allergic asthma, and suggest that women might benefit more from anti-LT asthma therapy.

Effect of Indoxyl Sulfate on the Repair and Intactness of Intestinal Epithelial Cells: Role of Reactive Oxygen Species' Release.

Chronic kidney disease (CKD) is characterized by an oxidative stress status, driving some CKD-associated complications, even at the gastrointestinal level. Indoxyl Sulfate (IS) is a protein-bound uremic toxin, poorly eliminated by dialysis. This toxin is able to affect the intestinal system, but its molecular mechanism/s in intestinal epithelial cells (IECs) remain poorly understood. This study's aim was to evaluate the effect of IS (31.2-250 µM) on oxidative stress in IEC-6 cells and on the intactness of IECs monolayers. Our results indicated that IS enhanced oxidative cell damage by inducing reactive oxygen species (ROS) release, reducing the antioxidant response and affecting Nuclear factor (erythroid-derived 2)-like 2 (Nrf2) nuclear translocation as well its related antioxidant enzymes. In the wound healing assay model, IS reduced IEC-6 migration, slightly impaired actin cytoskeleton rearrangement; this effect was associated with connexin 43 alteration. Moreover, we reported the effect of CKD patients' sera in IEC-6 cells. Our results indicated that patient sera induced ROS release in IEC-6 cells directly related to IS sera content and this effect was reduced by AST-120 serum treatment. Results highlighted the effect of IS in inducing oxidative stress in IECs and in impairing the intactness of the IECs cell monolayer, thus significantly contributing to CKD-associated intestinal alterations.

Two likely targets for the anti-cancer effect of indole derivatives from cruciferous vegetables: PI3K/Akt/mTOR signalling pathway and the aryl hydrocarbon receptor.

Diets containing high quantities of plant foods are linked with a decreased likelihood of incidence of cancer. Several common plant-based dietary components exert effects on DNA methylation levels, and can positively influence genome stability and the transcription of tumor suppressors and oncogenes. Indole-3-carbinol (I3C) is a substance present in vegetables of the Brassicaeae family, especially broccoli, white cabbage, Brussels sprouts and cauliflower. The in vivo biological effects of I3C are ascribed to a series of oligomeric products (including 3,3'-diindolylmethane), developed under acidic conditions. I3C is one of the many natural products and bioactive compounds found in foods which have recently received much attention for its potential effects in cancer prevention and treatment. In vitro studies report that I3C suppresses the proliferation of different tumor cells, including those isolated from breast, prostate, endometrium, and colon cancers. I3C resulted to be a potent in vivo chemopreventive agent for certain hormone-dependent cancers, including breast and cervical cancer. However, the mechanisms underlying these effects are not well defined. In this review, we have analysed recent literature on the use of indole derivatives against various forms of cancer, and have identified the main signalling pathways involved in their anti-cancer effect as PI3K/Akt/mTOR and the aryl hydrocarbon receptor.

Diazoxide Improves Mitochondrial Connexin 43 Expression in a Mouse Model of Doxorubicin-Induced Cardiotoxicity.

Doxorubicin (DOXO) administration induces alterations in Connexin 43 (Cx43) expression and localization, thus, inducing alterations in chemical and electrical signal transmission between cardiomyocytes and in intracellular calcium homeostasis even evident after a single administration. This study was designed to evaluate if Diazoxide (DZX), a specific opener of mitochondrial KATP channels widely used for its cardioprotective effects, can fight DOXO-induced cardiotoxicity in a short-time mouse model. DZX (20 mg/kg i.p.) was administered 30 min before DOXO (10 mg/kg i.p.) in C57BL/6j female mice for 1-3 or seven days once every other day. A recovery of cardiac parameters, evaluated by Echocardiography, were observed in DZX+DOXO co-treated mice. Western blot analysis performed on heart lysates showed an increase in sarco/endoplasmic reticulum Ca2+-ATPase (SERCAII) and a reduction in phospholamban (PLB) amounts in DZX+DOXO co-treated mice. A contemporary recovery of intracellular Ca2+-signal, detected spectrofluorometrically by means of FURA-2AM, was observed in these mice. Cx43 expression and localization, analyzed by Western blot and confirmed by immunofluorescence analysis, showed that DZX co-treatement increases Cx43 amount both on sarcoplasmic membrane and on mitochondria. In conclusion, our data demonstrate that, in a short-time mouse model of DOXO-induced cardiotoxicity, DZX exerts its cardioprotective effects also by enhancing the amount Cx43.

Soluble CD73 as biomarker in patients with metastatic melanoma patients treated with nivolumab.

BACKGROUND: Nivolumab is an anti-PD1 checkpoint inhibitor active in patients with advanced melanoma and as adjuvant therapy in high-risk metastatic melanoma patients. METHODS: In this single-center retrospective analysis, we investigated the CD73 enzyme activity in patients with metastatic melanoma stage IV and its correlation with the response to nivolumab. The soluble CD73 (sCD73) enzyme activity was measured in the serum of 37 melanoma patients before receiving nivolumab and the Harrel's C index was used to find the best cut-off for this biomarker. The multivariate Cox proportional hazard model was used to evaluate the prognostic value of CD73 enzyme activity for survival and progression-free survival. RESULTS: Our results show that high levels of sCD73 enzyme activity were significantly associated with poor overall survival and progression-free survival in patients with metastatic melanoma. The median progression-free survival was 2.6 months [95% confidence interval (CI) 1.9-3.3] in patients with high sCD73 enzyme activity (> 27.8 pmol/min/mg protein), and 14.2 months (95% CI 4.6-23.8) in patients with lower CD73 enzyme activity, when patients were follow-up for a median of 24 months range. The median overall survival was not reached in patients with low sCD73 activity (< 27.8 pmol/min/mg protein) compared with 6.1 months (95% CI 0-14.8) in patients with higher sCD73 activity. In multivariate analyses, the sCD73 enzyme activity emerged as the strongest prognostic factor for overall survival and progression-free survival. Elevated basal levels of sCD73 enzyme activity, before starting nivolumab treatment, were associated with lower response rates to therapy. CONCLUSIONS: We observed a significant association between the activity of sCD73 in the blood and clinical outcomes in patients with metastatic melanoma stage IV, receiving nivolumab. Although our results need to be confirmed and validated, we suggest that sCD73 might be used as serologic prognostic biomarker. Potentially evaluating sCD73 enzyme activity in the peripheral blood before treatment could help to estimate the response to nivolumab.

Cardiotoxic Effects of Short-Term Doxorubicin Administration: Involvement of Connexin 43 in Calcium Impairment.

The use of Doxorubicin (DOXO), a potent antineoplastic agent, is limited by the development of cardiotoxicity. DOXO-induced cardiotoxicity is multifactorial, although alterations in calcium homeostasis, seem to be involved. Since even the Connexin43 (Cx43) plays a pivotal role in these two phenomena, in this study we have analyzed the effects of DOXO on Cx43 expression and localization. Damage caused by anthracyclines on cardiomyocytes is immediate after each injection, in the present study we used a short-term model of DOXO-induced cardiomyopathy. C57BL/6j female mice were randomly divided in groups and injected with DOXO (2 or 10 mg/kg i.p.) for 1-3 or 7 days once every other day. Cardiac function was assessed by Echocardiography. Sarco/endoplasmic reticulum Ca2+-ATPase (SERCAII) and phospholamban (PLB) expression were assessed by Western blot analysis, intracellular [Ca2+] were detected spectrofluorometrically by means of Fura-2 pentakis (acetoxymethyl) ester (FURA-2AM), and Cx43 and pCx43 expression and localization was analyzed by Western blot and confirmed by immunofluorescence analysis. DOXO induces impairment in Ca2+ homeostasis, already evident after a single administration, and affects Cx43 expression and localization. Our data suggest that DOXO-induced alterations in Ca2+ homeostasis causes in the cells the induction of compensatory mechanisms until a certain threshold, above which cardiac injury is triggered.

Human lung cancer-derived immunosuppressive plasmacytoid dendritic cells release IL-1α in an AIM2 inflammasome-dependent manner.

Plasmacytoid dendritic cells (pDCs) highly populate lung tumor masses and are strictly correlated to bad prognosis, yet their role in lung cancer is controversial. To understand their role in lung cancer, we isolated pDCs from human samples of lung obtained from non-small cell lung cancer patients undergoing thoracic surgery. Tumor masses presented a higher percentage of pDCs than healthy tissues; pDCs were in the immunosuppressive phenotype, as determined by higher levels of CD33 and PD-L1. Despite higher HLA-A and HLA-D expression, cancerous pDCs did not exert cytotoxic activity against tumor cells but instead promoted their proliferation. In this scenario, cancerous pDCs were able to produce high levels of IL-1α. This effect was observed on the specific activation of the inflammasome absent in melanoma 2 (AIM2), which led to higher cytoplasmic calcium release responsible for calpain activation underlying IL-1α release. The blockade of type I interferon receptor and of AIM2 via the addition of LL-37 significantly reduced the release of IL-1α, which was still high after Nod-like receptor P3 inhibition via glibenclamide. More important, mitochondrial-derived reactive oxygen species sequester diminished AIM2-dependent IL-1α release. Our data demonstrate that lung tumor-associated pDCs are responsive to the activation of AIM2 that promotes calcium efflux and reactive oxygen species from mitochondria, leading to calpain activation and high levels of IL-1α, which facilitate tumor cell proliferation in the lung.

Inflammatory mediators in a short-time mouse model of doxorubicin-induced cardiotoxicity.

Doxorubicin (DOXO) is commonly used to treat a wide range of malignant tumors, but its clinical use is limited by acute and chronic cardiotoxicity. The precise mechanism underlying DOXO-induced cardiotoxicity is still not completely elucidated, but cardiac inflammation seems to be involved. Effects of DOXO on proinflammatory cytokines, inflammatory cell infiltration, and necrosis have been proven only when a functional impairment has already occurred, so this study aimed to investigate the acute effect of DOXO administration in mouse heart. The results of our study demonstrated alterations in cardiac function parameters assessed by ultrasound within 24h after a single injection of DOXO, with a cumulative effect along the increase of the dose and the number of DOXO administrations. At the same time, DOXO causes a significant production of proinflammatory cytokines (such as TNF-α and IL-6) with a concomitant reduction of IL-10, a well-known antiinflammatory cytokine. Furthermore, overexpression of inducible nitric oxide synthase (iNOS) in heart tissue and increased levels of serum nitrite in DOXO-treated mice were detected. Notably, DOXO administration significantly increased nitrotyrosine expression in mouse heart. Our data support the hypothesis that these early events, could be responsible for the later onset of more severe deleterious remodeling leading to DOXO induced cardiomyopathy.

Disodium cromoglycate inhibits asthma-like features induced by sphingosine-1-phosphate.

Compelling evidence suggests the involvement of sphingosine-1-phosphate (S1P) in the pathogenesis of asthma. The systemic administration of S1P causes asthma like features in the mouse involving mast cells. In this study we investigated whether disodium cromoglycate (DSCG), administered as a preventative treatment as in human therapy, could affect S1P effects on airways. BALB/c mice, treated with DSCG, received subcutaneous administration of S1P. Bronchi and pulmonary tissues were collected and functional, molecular and cellular studies were performed. DSCG inhibited S1P-induced airway hyper-reactivity as well as pulmonary inflammation. DSCG decreased the recruitment of solely mast cells and B cells in the lung. IgE serum levels, prostaglandin D2, mucus production and IL-13 were also reduced when mice were pretreated with DSCG. S1P induced pulmonary expression of CD23 on T and B cells, that was reversed by DSCG. Conversely, S1P failed to upregulate CD23 in mast cell-deficient Kit W-sh/W-sh mice. In conclusion we have shown that DSCG inhibits S1P-induced asthma like features in the mouse. This beneficial effect is due to a regulatory action on mast cell activity, and in turn to an inhibition of IgE-dependent T and B cells responses.

B cell depletion increases sphingosine-1-phosphate-dependent airway inflammation in mice.

Sphingosine-1-phosphate (S1P) has been widely associated with inflammation-based lung pathologies. Because B cells play a critical role as antigen-presenting and/or Ig-producing cells during asthmatic conditions, we wanted to dissect the role of these cells in S1P-dependent airway hyperreactivity and inflammation. Mice were sensitized to ovalbumin or exposed to S1P. Ovalbumin sensitization caused airway hyperreactivity coupled to an increased lung infiltration of B cells, which was significantly reduced after the inhibition of sphingosine kinases I/II. Similarly, the sole administration of S1P increased bronchial reactivity compared with vehicle and was accompanied by a higher influx of B cells in a time-dependent manner. This effect was associated with higher levels of IL-13, transforming growth factor-ß, IL-10, and T regulatory cells. In addition, isolated S1P-derived lung B cells increased CD4(+) and CD8(+) T cell proliferation in vitro, and their suppressive nature at Day 14 was associated with the higher release of transforming growth factor-ß and IL-10 when they were cocultured. Therefore, to prove the role of B cells in S1P-mediated airway inflammation, and because CD20 expression, contrary to major hystocompatibility complex I and major hystocompatibility complex II, was up-regulated at Day 14, CD20(+) B cells were depleted by means of a specific monoclonal antibody. The absence of CD20(+) B cells increased airway reactivity and inflammation in S1P-treated mice compared with control mice. These data imply that sphingosine kinase/S1P-mediated airway inflammation is countered by B cells via the induction of an immune-suppressive environment to reduce asthma-like outcomes in mice.

A single infection with Chlamydia pneumoniae is sufficient to exacerbate atherosclerosis in ApoE deficient mice.

Several studies have demonstrated a strong link between Chlamydia pneumoniae (Cp) infection and atherosclerosis progression/exacerbation. Here, we try to understand whether a single administration of Cp could exacerbate atherosclerosis. Apoe(-/-) mice were intranasally infected with Cp followed by a high fat diet. Mice were sacrificed at different time points after Cp infection to monitor the development of the atheroma. Cp infection increased lipid content in the aortic sinus of Apoe(-/-) mice starting from 8 weeks. This was associated with increased numbers of active myeloid dendritic cells and plasmacytoid DCs which were co-localized with T-cells in the atherosclerotic plaque. The serum levels of IFN-γ showed a Th1-like environment typical of atherosclerosis. In conclusion, we demonstrate that one dose of Cp could exacerbate atherosclerotic lesion development, triggering innate immune cell accumulation early on that allowed the involvement of Th1-like cells in the exacerbation of the atherosclerotic plaque at later time points.