Fenretinide inhibited de novo ceramide synthesis and proinflammatory cytokines induced by Aggregatibacter actinomycetemcomitans

Identifying MS4A6A+ macrophages as potential contributors to the pathogenesis of nonalcoholic fatty liver disease, periodontitis, and type 2 diabetes mellitus

Purpose

Concrete epidemiological evidence has suggested the mutually-contributing effect respectively between nonalcoholic fatty liver disease (NAFLD), type 2 diabetes mellitus (T2DM), and periodontitis (PD); however, their shared crosstalk mechanism remains an open issue.

Method

The NAFLD, PD, and T2DM-related datasets were obtained from the NCBI GEO repository. Their common differentially expressed genes (DEGs) were identified and the functional enrichment analysis performed by the DAVID platform determined relevant biological processes and pathways. Then, the STRING database established a PPI network of such DEGs and topological analysis through Cytoscape 3.7.1 software along with the machine-learning analysis by the least absolute shrinkage and selection operator (LASSO) algorithm screened out hub characteristic genes. Their efficacy was validated by external datasets using the receiver operating characteristic (ROC) curve, and gene expression and location of the most robust one was determined using single-cell sequencing and immunohistochemical staining. Finally, the promising drugs were predicted through the CTD database, and the CB-DOCK 2 and Pymol platform mimicked molecular docking.

Result

Intersection of differentially expressed genes from three datasets identified 25 shared DEGs of the three diseases, which were enriched in MHC II-mediated antigen presenting process. PPI network and LASSO machine-learning analysis determined 4 feature genes, of which the MS4A6A gene mainly expressed by macrophages was the hub gene and key immune cell type. Molecular docking simulation chosen fenretinide as the most promising medicant for MS4A6A+ macrophages.

Conclusion

MS4A6A+ macrophages were suggested to be important immune-related mediators in the progression of NAFLD, PD, and T2DM pathologies.

Fenretinide induces apoptosis and synergises the apoptosis inducing effect of gemcitabine through inhibition of key signalling molecules involved in A549 cell survival in in silico and in vitro analyses

Fenretinide is a synthetic retinoid compound, which induces apoptosis via generating reactive oxygen species (ROS) and modulating PI3K/Akt/mTOR signalling pathway. We hypothesise that fenretinide's mechanism of action in triggering apoptosis may involve other targets, beside mTOR signalling pathway and it may augment apoptosis inducing effects of chemotherapeutic drugs in lung cancer. Time-lapse microscopy and Western blotting were used to evaluate apoptosis and apoptotic marker cleaved-Caspase 3 in A549 cells. Relative levels of protein phosphorylation and ROS were quantified by Human Phospho-Kinase Array Kit and CellROX® Green Reagent, respectively. Docking and simulation analyses of proteins and fenretinide interactions were identified and visualised by Discovery Studio Visualizer and AutoDock Vina software. Our results showed that fenretinide induced apoptosis in a dose dependant manner and combinations of fenretinide (5 μg/mL) and gemcitabine (1, 2, 4, 8 and 16 μg/mL) synergistically enhanced apoptosis in A549 cells. Fenretinide caused significant increase of cleaved-Caspase 3, de-phosphorylated p-S473 of Akt and failed to inhibit mTORC1 downstream targets. In silico results revealed that Akt required the lowest energy (-10.2 kcal/mol) to interact with fenretinide in comparison with other proteins. In conclusion, Akt may be exploited as a good target for induction of apoptosis in A549 cells and fenretinide has great potentials to fulfil this task. The mechanism by which fenretinide boosts the apoptosis inducing effects of gemcitabine, which is likely expected to be via inhibiting mTORC2 downstream targets. However, docking investigation revealed that fenretinide lacks specificity as it may also interact with several secondary targets beside Akt.

Cross-talk between bioactive lipid mediators and the unfolded protein response in ischemic stroke

Ischemic cerebral stroke is a severe medical condition that affects about 15 million people every year and is the second leading cause of death and disability globally. Ischemic stroke results in neuronal cell death and neurological impairment. Current therapies may not adequately address the deleterious metabolic changes and may increase neurological damage. Oxygen and nutrient depletion along with the tissue damage result in endoplasmic reticulum (ER) stress, including the Unfolded Protein Response (UPR), and neuroinflammation in the affected area and cause cell death in the lesion core. The spatio-temporal production of lipid mediators, either pro-inflammatory or pro-resolving, decides the course and outcome of stroke. The modulation of the UPR as well as the resolution of inflammation promotes post-stroke cellular viability and neuroprotection. However, studies about the interplay between the UPR and bioactive lipid mediators remain elusive and this review gives insights about the crosstalk between lipid mediators and the UPR in ischemic stroke. Overall, the treatment of ischemic stroke is often inadequate due to lack of effective drugs, thus, this review will provide novel therapeutical strategies that could promote the functional recovery from ischemic stroke.

The Sphingolipid-Signaling Pathway as a Modulator of Infection by SARS-CoV-2

Ceramides and other related sphingolipids, important cellular components linked to metabolic homeostasis and cardiometabolic diseases, have been found to be involved in different steps of the SARS-CoV-2 life cycle. Hence, changes in their physiological levels are identified as predictors of COVID-19 severity and prognosis, as well as potential therapeutic targets. In this review, an overview of the SARS-CoV-2 life cycle is given, followed by a description of the sphingolipid metabolism and its role in viral infection, with a particular focus on those steps required to finalize the viral life cycle. Furthermore, the use and development of pharmaceutical strategies to target sphingolipids to prevent and treat severe and long-term symptoms of infectious diseases, particularly COVID-19, are reviewed herein. Finally, research perspectives and current challenges in this research field are highlighted. Although many aspects of sphingolipid metabolism are not fully known, this review aims to highlight how the discovery and use of molecules targeting sphingolipids with reliable and selective properties may offer new therapeutic alternatives to infectious and other diseases, including COVID-19.

Polypeptides Isolated from Lactococcus lactis Alleviates Lipopolysaccharide (LPS)-Induced Inflammation in Ctenopharyngodon idella

The main purpose of the present study was to evaluate the anti-inflammatory activity of Lactococcus lactis BL52 and isolate active substances responsible for anti-inflammatory activity. Head-kidney (HK) macrophages were used for in vitro bioassay-guided isolation, and the structure of the two peptides was identified by mass spectrometry analysis. Lipopolysaccharide (LPS)-induced inflammatory responses in Ctenopharyngodon idella were also examined to evaluate the in vivo anti-inflammatory activity of active substances. Two active peptides were isolated by HPLC from L. lactis BL52, and an in vitro anti-inflammatory assay demonstrated that peptide ALBL1 and ALBL2 dose-dependently inhibited LPS-induced inflammatory cytokines TNF-α, IL-6, and IL-1β and inflammatory factors NO and PGE 2 production in macrophages (p < 0.05). After being treated with 20 mg/Kg peptide ALBL1 and ALBL2, the expression levels of TNF-α, IL-6, IL-1β, NO, and PGE 2 were significantly inhibited (p < 0.05). Results from the in vivo test showed that when the concentration of peptide ALBL1 and ALBL2 reached 30 mg/Kg, the LPS-induced upregulations of TNF-α, IL-6, IL-1β, NO, and PGE 2 were prevented. In addition, peptide ALBL1 and ALBL2 blocked the expression of Toll-like receptor 2 (TLR2) and then suppressed the phosphorylation of nuclear transcription factor-kappa B (NF-κB) p65 and degradation inhibitor of IκBα. Moreover, C. idella treated with peptide ALBL1 and ALBL2 can relieve pathological inflammatory responses caused by LPS. These results suggest that the anti-inflammatory properties of peptide ALBL1 and ALBL2 might be a result from the inhibition of IL-6, IL-1β, and TNF-α expressions through the downregulation of Toll2/NF-κB signaling pathways.

Fenretinide regulates macrophage polarization to protect against experimental colitis induced by dextran sulfate sodium

Fenretinide (4-HPR), a synthetic retinoid, has attracted attention for its anti-inflammation activity. However, few studies have evaluated the effects of 4-HPR on ulcerative colitis (UC). The present study was performed to investigate the therapeutic effects of 4-HPR on UC, and to explore the mechanisms mainly focused on macrophage polarization involved in this progress. Intraperitoneally administered 4-HPR particularly at dose of 100 mg/kg obviously alleviated UC symptoms and restrained the mRNA expression of colonic IL-1β, IL-6, and TNF-α in dextran sulfate sodium (DSS)-induced mice. Further analysis showed that 4-HPR decreased the mRNA expression of M1 macrophage markers IL-12 and iNOS, while increased M2 macrophage markers Ym1, Arg1 and MRC1 in colonic tissue of mice received DSS. Consistently, an in vitro study revealed that 4-HPR decreased inflammatory response and M1 polarization, while enhanced M2 polarization in LPS-induced RAW264.7 cells. Interestingly, 4-HPR remarkably activated PPAR-γ which was an important regulator of macrophage polarization both in colonic tissue of UC mice and in LPS-induced RAW264.7 cells. Furthermore, these effects of 4-HPR in vivo and in vitro including anti-inflammation and modulation of macrophage polarization were partially abolished by treatment with PPAR-γ antagonist GW9662, indicating that 4-HPR activated PPAR-γ to exert its activities. Taken together, this study demonstrated that 4-HPR might be a potent anti-UC agent that works by regulating macrophage polarization via PPARγ.

Pulmonary Delivery of Fenretinide: A Possible Adjuvant Treatment In COVID-19

At present, there is no vaccine or effective standard treatment for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection (or coronavirus disease-19 (COVID-19)), which frequently leads to lethal pulmonary inflammatory responses. COVID-19 pathology is characterized by extreme inflammation and amplified immune response with activation of a cytokine storm. A subsequent progression to acute lung injury (ALI) or acute respiratory distress syndrome (ARDS) can take place, which is often followed by death. The causes of these strong inflammatory responses in SARS-CoV-2 infection are still unknown. As uncontrolled pulmonary inflammation is likely the main cause of death in SARS-CoV-2 infection, anti-inflammatory therapeutic interventions are particularly important. Fenretinide N-(4-hydroxyphenyl) retinamide is a bioactive molecule characterized by poly-pharmacological properties and a low toxicity profile. Fenretinide is endowed with antitumor, anti-inflammatory, antiviral, and immunomodulating properties other than efficacy in obesity/diabetic pathologies. Its anti-inflammatory and antiviral activities, in particular, could likely have utility in multimodal therapies for the treatment of ALI/ARDS in COVID-19 patients. Moreover, fenretinide administration by pulmonary delivery systems could further increase its therapeutic value by carrying high drug concentrations to the lungs and triggering a rapid onset of activity. This is particularly important in SARS-CoV-2 infection, where only a narrow time window exists for therapeutic intervention.

Florfenicol alleviated lipopolysaccharide (LPS)-induced inflammatory responses in Ctenopharyngodon idella through inhibiting toll / NF-κB signaling pathways

The present study was conducted to evaluate the anti-inflammatory activity of florfenicol (FFC) against lipopolysaccharide (LPS)-induced inflammatory responses in Ctenopharyngodon idella in vivo and in vitro. Head-kidney (HK) macrophages were pre-treated with 10 μg/mL LPS and then exposed to different concentrations of FFC to determine its in vitro anti-inflammatory activity. Inhibitory effect of FFC on inflammatory mediators TNF-α, IL-6 and IL-1β, as well as LPS-induced nitric oxide (NO) and prostaglandin E 2 (PGE 2) production were assayed by ELISA. The expression level of nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) were investigated by RT-PCR. Expression level of TLR-related genes (TLR1, TLR2, TLR4, TLR7, TLR8) expression, tumor necrosis factor receptor-associated factor 6 (TRAF6), transforming growth factor-b-activated kinase 1 (TAK1), Myeloid differentiation factor 88 (MyD88), nucleus p65, NF-κBα (IκBα) were measured by RT-PCR after grass carp were treated with 50, 100 and 200 mg FFC/kg body weight for 3 days. Results from in vitro tests demonstrated that FFC dose-dependently inhibited LPS-induced inflammatory cytokines TNF-α, IL-6 and IL-1β, inflammatory factors NO and PGE 2 production in macrophages. In addition, iNOS and COX-2 expression levels decreased significantly as compared with LPS treated group. In vivo test demonstrated that treatment with FFC prevented the LPS-induced upregulation of TNF-α, IL-6, IL-1β, NO and PGE 2. The expression level of iNOS, and COX-2 in FFC-treated grass carp were also downregulated as compared with LPS treated fish. Besides, FFC blocked the expression of Toll-like receptor 2 (TLR2) and then suppressed the phosphorylation of nuclear transcription factor-kappa B (NF-κB) p65 and degradation inhibitor of IκBα. Furthermore, administration of FFC inhibited the up-regulation of IRAK4, TRAF6 and TAK1 induced by LPS. These results suggest that the anti-inflammatory properties of FFC might be the results from the inhibition of iNOS, COX-2, IL-6, IL-1β, and TNF-α expressions through the down-regulation of Toll/NF-κB signaling pathways.

Recent Advances on Topical Application of Ceramides to Restore Barrier Function of Skin

Human skin is the largest organ of the body and is an effective physical barrier keeping it from environmental conditions. This barrier function of the skin is based on stratum corneum, located in the uppermost skin. Stratum corneum has corneocytes surrounded by multilamellar lipid membranes which are composed of cholesterol, free fatty acids and ceramides (CERs). Alterations in ceramide content of the stratum corneum are associated with numerous skin disorders. In recent years, CERs have been incorporated into conventional and novel carrier systems with the purpose of exogenously applying CERs to help the barrier function of the skin. This review provides an overview of the structure, function and importance of CERs to restore the barrier function of the skin following their topical application.

Ceramide Imbalance and Impaired TLR4-Mediated Autophagy in BMDM of an ORMDL3-Overexpressing Mouse Model

Increased orosomucoid-like 3 (ORMDL3) expression levels, due to single nucleotide polymorphisms (SNPs), have been associated with several inflammatory diseases, including asthma and inflammatory bowel diseases. ORMDL proteins inhibit serine palmitoyltransferase (SPT), the first rate-limiting enzyme in de novo sphingolipid synthesis and alter cellular calcium homeostasis. Both processes are essential for immune response. The present study addresses ORMDL3 protein involvement in macrophage physiology using an overexpressing knock-in mouse model. Ceramide content was notably different in the bone-marrow-derived macrophages (BMDM) from the transgenic mouse model compared with the wild type (WT) macrophages. Our data revealed an alteration of de novo production of sphinganine upon BMDM activation in the transgenic mouse. Gene-expression analysis showed that alteration in ORMDL3 expression levels did not affect activation or macrophage polarization. Nevertheless, we studied phagocytosis and autophagy—crucial processes that are dependent on lipid membrane composition. Phagocytosis in transgenic macrophages was not affected by ORMDL3 overexpression, but we did find a reduction in toll-like receptor 4 (TLR-4)-mediated autophagy. Both genetic and functional studies have pointed to autophagy as an essential pathway involved in inflammation. We believe that our work provides new insights into the functional link between ORMDL3 expression and inflammatory diseases.

Fenretinide Inhibits Neutrophil Recruitment and IL-1β Production in Aspergillus fumigatus Keratitis

Purpose:

Fungal keratitis is a major cause of corneal ulcers, resulting in significant visual impairment and blindness. Fenretinide, a derivative of vitamin A, has been shown to suppress inflammation in a multitude of diseases. In this study, we aimed to characterize the effect of fenretinide in Aspergillus fumigatus keratitis of the eye in a mouse model.

Methods:

In vivo and in vitro experiments were performed in mouse models and THP-1 macrophage cell cultures infected with A. fumigatus, respectively. Experimental subjects were first pretreated with fenretinide, and then the effect of the compound was assessed with clinical evaluation, neutrophil staining, myeloperoxidase assay, quantitative polymerase chain reaction (qRT-PCR), and western blot.

Results:

We confirmed that fenretinide contributed to protection of corneal transparency during early mouse A. fumigatus keratitis by reducing neutrophil recruitment, decreasing myeloperoxidase (MPO) levels and increasing apoptosis. Compared with controls, fenretinide impaired proinflammatory cytokine interleukin 1 beta (IL-1β) production in response to A. fumigatus exposure with contributions by lectin-type oxidized LDL receptor 1 (LOX-1) and c-Jun N-terminal kinase (JNK).

Conclusions:

Together, these findings demonstrate that fenretinide may suppress inflammation through reduced neutrophil recruitment and inflammatory cytokine production in A. fumigatus keratitis.

Phosphoglycerol dihydroceramide, a distinctive ceramide produced by Porphyromonas gingivalis, promotes RANKL-induced osteoclastogenesis by acting on non-muscle myosin II-A (Myh9), an osteoclast cell fusion regulatory factor

Among several virulence factors produced by the periodontal pathogen Porphyromonas gingivalis (Pg), a recently identified novel class of dihydroceramide lipids that contains a long acyl-chain has the potential to play a pathogenic role in periodontitis because of its higher level of tissue penetration compared to other lipid classes produced by Pg. However, the possible impact of Pg ceramides on osteoclastogenesis is largely unknown. In the present study, we report that the phosphoglycerol dihydroceramide (PGDHC) isolated from Pg enhanced osteoclastogenesis in vitro and in vivo. Using RAW264.7 cells, in vitro assays indicated that PGDHC can promote RANKL-induced osteoclastogenesis by generating remarkably larger TRAP+ multinuclear osteoclasts compared to Pg LPS in a TLR2/4-independent manner. According to fluorescent confocal microscopy, co-localization of non-muscle myosin II-A (Myh9) and PGDHC was observed in the cytoplasm of osteoclasts, indicating the membrane-permeability of PGDHC. Loss- and gain-of-function assays using RNAi-based Myh9 gene silencing, as well as overexpression of the Myh9 gene, in RAW264.7 cells showed that interaction of PGDHC with Myh9 enhances RANKL-induced osteoclastogenesis. It was also demonstrated that PGDHC can upregulate the expression of dendritic cell-specific transmembrane protein (DC-STAMP), an important osteoclast fusogen, through signaling that involves Rac1, suggesting that interaction of PGDHC with Myh9 can elicit the cell signal that promotes osteoclast cell fusion. Taken together, our data indicated that PGDHC is a Pg-derived, cell-permeable ceramide that possesses a unique property of promoting osteoclastogenesis via interaction with Myh9 which, in turn, activates a Rac1/DC-STAMP pathway for upregulation of osteoclast cell fusion.

Sphingosine-1-Phosphate Receptor 2 Regulates Proinflammatory Cytokine Production and Osteoclastogenesis

Sphingosine-1-phosphate receptor 2 (S1PR2) couples with the Gi, Gq, and G_12/13 group of proteins, which modulate an array of cellular signaling pathways and affect immune responses to multiple stimuli. In this study, we demonstrated that knockdown of S1PR2 by a specific S1PR2 shRNA lentiviral vector significantly inhibited IL-1β, IL-6, and TNF-α protein levels induced by oral pathogen Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) in murine bone marrow-derived monocytes and macrophages (BMMs) compared with controls. In addition, knockdown of S1PR2 by the S1PR2 shRNA lentiviral vector suppressed p-PI3K, p-ERK, p-JNK, p-p38, and p-NF-κBp65 protein expressions induced by A. actinomycetemcomitans. Furthermore, bone marrow cells treated with the S1PR2 shRNA lentiviral vector inhibited osteoclastogenesis induced by RANKL compared with controls. The S1PR2 shRNA suppressed the mRNA levels of six osteoclastogenic factors including nuclear factor of activated T-cells cytoplasmic calcineurin-dependent 1 (NFATc1), cathepsin K (Ctsk), acid phosphatase 5 (Acp5), osteoclast-associated receptor (Oscar), dendritic cells specific transmembrane protein (Dcstamp), and osteoclast stimulatory transmembrane protein (Ocstamp) in bone marrow cells. We conclude that S1PR2 plays an essential role in modulating proinflammatory cytokine production and osteoclastogenesis. Blocking S1PR2 signaling might be a novel therapeutic strategy to treat inflammatory bone loss diseases.

Soyasaponin Ab inhibits lipopolysaccharide-induced acute lung injury in mice

Soyasaponin Ab (SA) has been reported to have anti-inflammatory effect. However, the effects of SA on lipopolysaccharide (LPS)-induced acute lung injury (ALI) have not been reported. The aim of this study was to investigate the anti-inflammatory effects of SA on LPS-induced ALI and clarify the possible mechanism. The mice were stimulated with LPS to induce ALI. SA was given 1h after LPS treatment. 12h later, lung tissues were collected to assess pathological changes and edema. Bronchoalveolar lavage fluid (BALF) was collected to assess inflammatory cytokines and nitric oxide (NO) production. In vitro, mice alveolar macrophages were used to investigate the anti-inflammatory mechanism of SA. Our results showed that SA attenuated LPS-induced lung pathological changes, edema, the expression of cycloxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) in lung tissues, as well as TNF-α, IL-6, IL-1β, and NO production in mice. Meanwhile, SA up-regulated the activities of superoxide dismutase (SOD) and catalase decreased by LPS in mice. SA also inhibited LPS-induced TNF-α, IL-6 and IL-1β production as well as NF-κB activation in alveolar macrophages. Furthermore, SA could activate Liver X Receptor Alpha (LXRα) and knockdown of LXRα by RNAi abrogated the anti-inflammatory effects of SA. In conclusion, the current study demonstrated that SA exhibited protective effects against LPS-induced acute lung injury and the possible mechanism was involved in activating LXRα, thereby inhibiting LPS-induced inflammatory response.

Diet and asthma: an update

PURPOSE OF REVIEW

Our objective was to provide an overview and discussion of recent experimental studies, epidemiologic studies, and clinical trials of diet and asthma. We focus on dietary sources and vitamins with antioxidant properties [vitamins (A, C, and E), folate, and omega-3 and omega-6 polyunsaturated fatty acids (n-3 and n-6 PUFAs)].

RECENT FINDINGS

Current evidence does not support the use of vitamin A, vitamin C, vitamin E, or PUFAs for the prevention or treatment of asthma or allergies. Current guidelines for prenatal use of folate to prevent neural tube defects should be followed, as there is no evidence of major effects of this practice on asthma or allergies. Consumption of a balanced diet that is rich in sources of antioxidants (e.g. fruits and vegetables) may be beneficial in the primary prevention of asthma.

SUMMARY

None of the vitamins or nutrients examined is consistently associated with asthma or allergies. In some cases, further studies of the effects of a vitamin or nutrient on specific asthma phenotypes (e.g. vitamin C to prevent viral-induced exacerbations) are warranted. Clinical trials of 'whole diet' interventions to prevent asthma are advisable on the basis of existing evidence.

FTY720 inhibited proinflammatory cytokine release and osteoclastogenesis induced by Aggregatibacter actinomycetemcomitans

BACKGROUND

Periodontitis is a bacteria-driven inflammatory bone loss disease. Previous studies showed that the oral pathogen Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) stimulated the generation of sphingosine 1 phosphate (S1P). In addition, S1P signaling regulated the migration of osteoclast precursors and affected osteoclastogenesis. Furthermore, treatment with FTY720 (also called fingolimod, a modulator of multiple S1P receptors) alleviated osteoporosis and suppressed arthritis in animals. This study determined the effect of FTY720 on proinflammatory cytokine production and osteoclastogenesis in murine bone marrow cells with or without A. actinomycetemcomitans stimulation.

METHODS

Murine bone marrow-derived monocytes and macrophages (BMMs) were treated with vehicle ethanol or FTY720, and were either unstimulated or stimulated for 0.5 to 6 h with A. actinomycetemcomitans. The protein levels of interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α in the media of BMMs were quantified by enzyme-linked immunosorbent assay (ELISA). Protein expressions, including phosphorylated phosphoinositide 3-kinase (p-PI3K), p-Akt, p-extracellular signal-regulated kinase (p-ERK), PI3K, Akt, and ERK were evaluated by Western blot. In addition, murine bone marrow-derived pre-osteoclasts were treated with macrophage colony-stimulating factor (M-CSF) and receptor activator of nuclear factor kappa-B ligand (RANKL) for three days. Then the cells were treated with either vehicle or FTY720 and were either unstimulated or stimulated with A. actinomycetemcomitans for 4 to 24 h. Control cells were treated with M-CSF alone with or without bacterial stimulation. Osteoclasts were stained by tartrate-resistant acid phosphatase (TRAP) staining. The mRNA levels of osteoclastogenic factors, including nuclear factor of activated T-cells cytoplasmic calcineurin-dependent 1 (Nfatc1), cathepsin K (Ctsk), acid phosphatase 5 (Acp5), osteoclast-associated receptor (Oscar), and RANKL were quantified by quantitative real-time polymerase chain reaction (PCR).

RESULTS

FTY720 dose-dependently inhibited IL-1β, IL-6, and TNF-α protein levels induced by A. actinomycetemcomitans in BMMs compared with controls. Additionally, FTY720 attenuated p-PI3K, p-Akt, and p-ERK expressions induced by A. actinomycetemcomitans. Furthermore, FTY720 suppressed osteoclastogenesis in bone marrow-derived pre-osteoclasts with or without bacterial stimulation and reduced the mRNA levels of Nfatc1, Ctsk, Acp5, and Oscar, but not RANKL in bone marrow-derived pre-osteoclasts.

CONCLUSION

FTY720 inhibited proinflammatory cytokine production and suppressed osteoclastogenesis, supporting FTY720 as a potential therapy for inflammatory bone loss diseases.

Pinocembrin inhibits lipopolysaccharide-induced inflammatory mediators production in BV2 microglial cells through suppression of PI3K/Akt/NF-κB pathway

Pinocembrin, one of the primary flavonoids from Pinus heartwood and Eucalyptus, has been reported to have anti-inflammatory and antioxidant activity. This study was designed to evaluate the inhibitory effects of pinocembrin on inflammatory mediators production in LPS-stimulated BV2 microglial cells. The results showed that pinocembrin dose-dependently inhibited LPS-induced inflammatory mediators TNF-α, IL-1β, NO and PGE2 production. Pinocembrin also inhibited LPS-induced iNOS and COX-2 expression. Moreover, pinocembrin inhibited LPS-induced PI3K, Akt phosphorylation, and NF-κB activation, which were required for inflammatory mediators production. Furthermore, treatment of pinocembrin induced nuclear translocation of Nrf2 and expression of HO-1. In conclusion, our data indicated that pinocembrin inhibited LPS-induced inflammatory mediators production by suppressing PI3K/Akt/NF-κB signaling pathway.

Salvianolic acid B attenuates lung inflammation induced by cigarette smoke in mice

Salvianolic acid B (Sal B), a bioactive compound isolated from the Chinese herb Radix Salviae Miltiorrhizae, has been reported to exhibit anti-inflammatory and anti-oxidantive effects. The aim of this study was to investigate the protective effects of Sal B on cigarette smoke (CS)-induced acute lung inflammation. Sal B was given intraperitoneally (i.p.) to mice 1h before CS exposure daily for four consecutive days. Bronchoalveolar lavage fluid (BALF) was collected to assess the levels of inflammatory cytokines and cell counts. Lung tissues were used to analysis pathological changes, total glutathione (GSH), nuclear factor erythroid-2 related factor 2 (Nrf-2), and nuclear factor-kappa B (NF-κB) expression. The results showed that Sal B inhibited CS-induced lung pathological changes, the infiltration of inflammatory cells, tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-1β (IL-1β), and monocyte chemoattractant protein 1 (MCP-1) productions. Sal B also up-regulated CS-induced total glutathione (GSH) production. Furthermore, Sal B was found to up-regulate Nrf-2, hemeoxygenase1 (HO1) expression and suppress CS-induced NF-κB activation. In conclusion, the current study demonstrated that Sal B exhibited a protective effect on CS-induced lung injury and the possible mechanism was involved in activating Nrf-2 and inhibiting NF-κB activation.

Periodontal inflammation and alveolar bone loss induced by Aggregatibacter actinomycetemcomitans is attenuated in sphingosine kinase 1-deficient mice

BACKGROUND AND OBJECTIVE

Sphingosine-1-phosphate (S1P) is a bioactive sphingolipid, which is generated by activation of sphingosine kinase (SK) 1 and/or 2 in most mammalian cells with various stimuli, including the oral pathogen Aggregatibacter actinomycetemcomitans. S1P signaling has been shown to regulate the migration of monocytes and macrophages (osteoclast precursors) from the circulation to bone tissues and affect bone homeostasis. We aimed to determine the effects of SK1 deficiency on S1P generation, proinflammatory cytokine production, chemotaxis of monocytes and macrophages, and periodontitis induced by A. actinomycetemcomitans.

MATERIAL AND METHODS

Murine bone marrow-derived monocytes and macrophages (BMMs) from SK1 knockout (KO) mice or wild-type (WT) mice were either untreated or exposed to A. actinomycetemcomitans. The mRNA levels of SK1, SK2 and intracellular sphingolipid levels were quantified. In addition, murine WT BMMs were treated with vehicle, S1P, with or without A. actinomycetemcomitans and the mRNA levels of cyclooxygenase 2 (COX-2), interleukin (IL)-1β, IL-6 and tumor necrosis factor (TNF) were quantified. The protein levels of prostaglandin E2, IL-1β, IL-6 and TNF-α were quantified in the cell media of SK1 KO BMMs or WT BMMs with or without bacterial stimulation. Furthermore, a transwell migration assay was performed and the number of migrated WT BMMs in the presence of vehicle, bacteria-stimulated media, with or without S1P was quantified. Finally, in vivo studies were performed on SK1 KO and WT mice by injecting either phosphate-buffered saline or A. actinomycetemcomitans in the periodontal tissues. The mice maxillae were scanned by micro-computed tomography, and alveolar bone volume was analyzed. The number of periodontal leukocytes and osteoclasts were quantified in maxillary tissue sections.

RESULTS

SK1 mRNA levels significantly increased after A. actinomycetemcomitans stimulation in murine WT BMMs, but were undetectable in SK1 KO BMMs. Deficiency of SK1 in murine BMMs resulted in decreased S1P generation induced by A. actinomycetemcomitans as compared with WT BMMs. Additionally, low levels of S1P (≤ 1 μM) did not have a significant impact on the mRNA production of COX-2, IL-1β, IL-6 and TNF in murine BMMs with or without the presence of A. actinomycetemcomitans. There were no significant differences in prostaglandin E2 , IL-1β, IL-6 and TNF-α protein levels in the media between SK1 KO BMMs and WT BMMs with or without bacterial stimulation. Importantly, low levels of S1P (≤ 1 μM) dose-dependently promoted the chemotaxis of BMMs. The bacteria-stimulated media derived from SK1 BMMs significantly reduced the chemotaxis response compared with WT control. Finally, SK1 KO mice showed significantly attenuated alveolar bone loss stimulated by A. actinomycetemcomitans compared with WT mice treated with A. actinomycetemcomitans. Histological analysis of periodontal tissue sections revealed that SK1 KO mice treated with A. actinomycetemcomitans significantly reduced the number of infiltrated periodontal leukocytes and mature osteoclasts attached on the alveolar bone compared with WT mice.

CONCLUSION

Our studies support that SK1 and S1P play an important role in the inflammatory bone loss response induced by the oral pathogen A. actinomycetemcomitans. Reducing S1P generation by inhibiting SK1 has the potential as a novel therapeutic strategy for periodontitis and other inflammatory bone loss diseases.

Fenretinide prevents inflammation and airway hyperresponsiveness in a mouse model of allergic asthma

Arachidonic acid (AA) and docosahexaenoic acid (DHA) play important roles in inflammation and disease progression, where AA is viewed as proinflammatory and DHA as antiinflammatory. We observe in our model of allergic asthma that the AA/DHA ratio is significantly skewed in a proinflammatory direction. Fenretinide, a vitamin A derivative, has been shown to correct fatty acid imbalances in other diseases. Therefore, we explored if fenretinide can have a protective effect in allergic asthma. To accomplish this, we measured the levels of AA and DHA in the lungs of nonallergic, ovalbumin-induced allergic, and fenretinide-treated allergic mice. We also investigated the effect of allergic asthma and fenretinide treatment on markers of oxidative stress, levels of metabolites, IgE production, airway hyperresponsiveness, and histological changes. Our data demonstrate that treatment of allergen-sensitized mice with fenretinide before allergen challenge prevents ovalbumin-induced changes in the AA/DHA ratio. The levels of several metabolites, such as serotonin, and markers of cellular stress, which are increased after ovalbumin challenge, are also controlled by fenretinide treatment. We observed the protective effect of fenretinide against ovalbumin-induced airway hyperresponsiveness and inflammation in the lungs, illustrated by a complete block in the infiltration of inflammatory cells to the airways and dramatically diminished goblet cell proliferation, even though IgE remained high. Our results demonstrate that fenretinide is an effective agent targeting inflammation, oxidation, and lung pathology observed in allergic asthma.

Coordinated regulation of the orosomucoid-like gene family expression controls de novo ceramide synthesis in mammalian cells

The orosomucoid-like (ORMDL) protein family is involved in the regulation of de novo sphingolipid synthesis, calcium homeostasis, and unfolded protein response. Single nucleotide polymorphisms (SNPs) that increase ORMDL3 expression have been associated with various immune/inflammatory diseases, although the pathophysiological mechanisms underlying this association are poorly understood. ORMDL proteins are claimed to be inhibitors of the serine palmitoyltransferase (SPT). However, it is not clear whether individual ORMDL expression levels have an impact on ceramide synthesis. The present study addressed the interaction with and regulation of SPT activity by ORMDLs to clarify their pathophysiological relevance. We have measured ceramide production in HEK293 cells incubated with palmitate as a direct substrate for SPT reaction. Our results showed that a coordinated overexpression of the three isoforms inhibits the enzyme completely, whereas individual ORMDLs are not as effective. Immunoprecipitation and fluorescence resonance energy transfer (FRET) studies showed that mammalian ORMDLs form oligomeric complexes that change conformation depending on cellular sphingolipid levels. Finally, using macrophages as a model, we demonstrate that mammalian cells modify ORMDL genes expression levels coordinately to regulate the de novo ceramide synthesis pathway. In conclusion, we have shown a physiological modulation of SPT activity by general ORMDL expression level regulation. Moreover, because single ORMDL3 protein alteration produces an incomplete inhibition of SPT activity, this work argues against the idea that ORMDL3 pathophysiology could be explained by a simple on/off mechanism on SPT activity.

Anti-inflammatory action of lipid nanocarrier-delivered myriocin: therapeutic potential in cystic fibrosis

BACKGROUND

Sphingolipids take part in immune response and can initiate and/or sustain inflammation. Various inflammatory diseases have been associated with increased ceramide content, and pharmacological reduction of ceramide diminishes inflammation damage in vivo. Inflammation and susceptibility to microbial infection are two elements in a vicious circle. Recently, sphingolipid metabolism inhibitors were used to reduce infection. Cystic fibrosis (CF) is characterized by a hyper-inflammation and an excessive innate immune response, which fails to evolve into adaptive immunity and to eradicate infection. Chronic infections result in lung damage and patient morbidity. Notably, ceramide content in mucosa airways is higher in CF mouse models and in patients than in control mice or healthy subjects.

METHODS

The therapeutic potential of myriocin, an inhibitor of the sphingolipid de novo synthesis rate limiting enzyme (Serine Palmitoyl Transferase, SPT),was investigated in CF cells and mice models.

RESULTS

We treated CF human respiratory epithelial cells with myriocin, This treatment resulted in reduced basal, as well as TNFα-stimulated, inflammation. In turn, TNFα induced an increase in SPT in these cells, linking de novo synthesis of ceramide to inflammation. Furthermore, myriocin-loaded nanocarrier, injected intratrachea prior to P. aeruginosa challenge, enabled a significant reduction of lung infection and reduced inflammation.

CONCLUSIONS

The presented data suggest that de novo ceramide synthesis is constitutively enhanced in CF mucosa and that it can be envisaged as pharmacological target for modulating inflammation and restoring effective innate immunity against acute infection.

GENERAL SIGNIFICANCE

Myriocin stands as a powerful immunomodulatory agent for inflammatory and infectious diseases.