Role of S1P/S1PR3 axis in release of CCL20 from human bronchial epithelial cells

The link between the sphingolipid rheostat and obstructive sleep apnea

Chronic inflammation induced by hypoxia during sleep is an important mechanism of microvascular damage in OSA patients. In this study, we investigated the role of the sphingosine rheostat, which has diverse inflammatory effects. Thirty-seven healthy subjects and 31 patients with OSA were recruited. We collected data on demographics and comorbidities. Plasma sphingosine-1-phosphate and ceramide antibody concentrations were measured by ELISA. The results were compared between the OSA and control groups, and the correlations between these measurements and markers of disease severity and comorbidities were explored. Ceramide antibody levels were significantly elevated in OSA patients (892.17 ng/ml) vs. controls (209.55 ng/ml). S1P levels were also significantly higher in patients with OSA (1760.0 pg/ml) than in controls (290.35 pg/ml, p < 0.001). The ceramide antibody concentration showed correlations with BMI (ρ = 0.25, p = 0.04), CRP (ρ = 0.36, p = 0.005), AHI (ρ = 0.43, p < 0.001), ODI (ρ = 0.43, p < 0.001), TST90% (ρ = 0.35, p = 0.004) and the lowest oxygen saturation (ρ =  0.37, p = 0.001) in the whole study population but not when patients with OSA were analyzed separately. The elevated ceramide antibody and sphingosine-1-phosphate concentrations in patients suffering from OSA suggests their involvement in the pathomechanism of OSA and its comorbidities.

Environmental risks and sphingolipid signatures in adult asthma and its phenotypic clusters: a multicentre study

BACKGROUND

Adult asthma is phenotypically heterogeneous with unclear aetiology. We aimed to evaluate the potential contribution of environmental exposure and its ensuing response to asthma and its heterogeneity.

METHODS

Environmental risk was evaluated by assessing the records of National Health Insurance Research Database (NHIRD) and residence-based air pollution (particulate matter with diameter less than 2.5 micrometers (PM_2.5) and PM_2.5-bound polycyclic aromatic hydrocarbons (PAHs)), integrating biomonitoring analysis of environmental pollutants, inflammatory markers and sphingolipid metabolites in case-control populations with mass spectrometry and ELISA. Phenotypic clustering was evaluated by t-distributed stochastic neighbor embedding (t-SNE) integrating 18 clinical and demographic variables.

FINDINGS

In the NHIRD dataset, modest increase in the relative risk with time-lag effect for emergency (N=209 837) and outpatient visits (N=638 538) was observed with increasing levels of PM_2.5 and PAHs. Biomonitoring analysis revealed a panel of metals and organic pollutants, particularly metal Ni and PAH, posing a significant risk for current asthma (ORs=1.28-3.48) and its severity, correlating with the level of oxidative stress markers, notably Nε-(hexanoyl)-lysine (r=0.108-0.311, p<0.05), but not with the accumulated levels of PM_2.5 exposure. Further, levels of circulating sphingosine-1-phosphate and ceramide-1-phosphate were found to discriminate asthma (p<0.001 and p<0.05, respectively), correlating with the levels of PAH (r=0.196, p<0.01) and metal exposure (r=0.202-0.323, p<0.05), respectively, and both correlating with circulating inflammatory markers (r=0.186-0.427, p<0.01). Analysis of six phenotypic clusters and those cases with comorbid type 2 diabetes mellitus (T2DM) revealed cluster-selective environmental risks and biosignatures.

INTERPRETATION

These results suggest the potential contribution of environmental factors from multiple sources, their ensuing oxidative stress and sphingolipid remodeling to adult asthma and its phenotypic heterogeneity.

The Crosstalk between FcεRI and Sphingosine Signaling in Allergic Inflammation

Sphingolipid molecules have recently attracted attention as signaling molecules in allergic inflammation diseases. Sphingosine-1-phosphate (S1P) is synthesized by two isoforms of sphingosine kinases (SPHK 1 and SPHK2) and is known to be involved in various cellular processes. S1P levels reportedly increase in allergic inflammatory diseases, such as asthma and anaphylaxis. FcεRI signaling is necessary for allergic inflammation as it can activate the SPHKs and increase the S1P level; once S1P is secreted, it can bind to the S1P receptors (S1PRs). The role of S1P signaling in various allergic diseases is discussed. Increased levels of S1P are positively associated with asthma and anaphylaxis. S1P can either induce or suppress allergic skin diseases in a context-dependent manner. The crosstalk between FcεRI and S1P/SPHK/S1PRs is discussed. The roles of the microRNAs that regulate the expression of the components of S1P signaling in allergic inflammatory diseases are also discussed. Various reports suggest the role of S1P in FcεRI-mediated mast cell (MC) activation. Thus, S1P/SPHK/S1PRs signaling can be the target for developing anti-allergy drugs.

The Role of Sphingolipids in Allergic Disorders

Allergy is defined as a complex chronic inflammatory condition in which genetic and environmental factors are implicated. Sphingolipids are involved in multiple biological functions, from cell membrane components to critical signaling molecules. To date, sphingolipids have been studied in different human pathologies such as neurological disorders, cancer, autoimmunity, and infections. Sphingolipid metabolites, in particular, ceramide and sphingosine-1-phosphate (S1P), regulate a diverse range of cellular processes that are important in immunity and inflammation. Moreover, variations in the sphingolipid concentrations have been strongly associated with allergic diseases. This review will focus on the role of sphingolipids in the development of allergic sensitization and allergic inflammation through the activation of immune cells resident in tissues, as well as their role in barrier remodeling and anaphylaxis. The knowledge gained in this emerging field will help to develop new therapeutic options for allergic disorders.

The lncRNA H19/miR-766-3p/S1PR3 Axis Contributes to the Hyperproliferation of Keratinocytes and Skin Inflammation in Psoriasis via the AKT/mTOR Pathway

Background

The pathogenesis of long noncoding RNAs (lncRNAs) and microRNAs (miRNAs) are well studied in psoriasis. However, little is known about how specific lncRNAs and miRNAs affect the mechanism of psoriasis development and which pathways are involved.

Objectives

To explore the role of the lncRNA H19/miR-766-3p/S1PR3 axis in psoriasis.

Methods

miRNA and lncRNA microarrays were performed using IL-22-induced HaCaT cells and psoriatic lesions, respectively. Fluorescence in situ hybridization and quantitative reverse-transcriptase polymerase chain reaction were used to detect the expression of miR-766-3p and lncRNA H19. Luciferase reporter assays were used to identify miR-766-3p/lncRNA H19 and miR-766-3p/S1PR3 combinations. CCK-8 and ELISA were performed to evaluate the proliferation of keratinocytes and the secretion of pro-inflammatory cytokines. Western blot analysis was used to detect the expression of S1PR3 and its downstream effector proteins.

Results

MiR-766-3p was upregulated in both HaCaT cells treated with the psoriasis-related cytokine pool (IL-17A, IL-22, IL-1 alpha, oncostatin M, and TNF-alpha) and tissues. Overexpression of miR-766-3p promoted keratinocyte proliferation and IL-17A and IL-22 secretion. LncRNA H19 and S1PR3 were demonstrably combined with miR-766-3p by luciferase reporter assay. lncRNA H19 repressed proliferation and inflammation, which were reduced by the miR-766-3p. AKT/mTOR pathway effected proliferation and inflammation by the lncRNA H19/miR-766-3p/S1PR3 axis.

Conclusions

We established that downregulation of lncRNA H19 promoted the proliferation of keratinocytes and skin inflammation by up-regulating miR-766-3p expression levels and inhibiting activation of S1PR3 through the AKT/mTOR pathway in psoriasis.

Propionate and Butyrate Produced by Gut Microbiota after Probiotic Supplementation Attenuate Lung Metastasis of Melanoma Cells in Mice

SCOPE

The beneficial effects of probiotics in reducing gastrointestinal inflammation and in preventing colorectal cancer have been reported, but the mechanism underlying the immunomodulatory effect of probiotics in inhibiting extra-intestinal tumor progression remains unclear.

METHODS AND RESULTS

This study shows that probiotic supplementation attenuate lung metastasis of melanoma cells in mice. Feeding mice with VSL#3 probiotics change the composition and proportion of gut microbiota. The changes in gut bacteria composition, such as in the abundance of Lachnospiraceae, Streptococcus, and Lachnoclostridium, are associated with the production of short-chain fatty acids in the gut. The concentrations of propionate and butyrate are upregulated in gut and blood after feeding VSL#3, and the increase in propionate and butyrate levels promotes the expression of chemokine (C-C motif) ligand 20 (CCL20) in lung endothelial cells and the recruitment of T helper 17 (Th17) cells to the lungs via the CCL20/chemokine receptor 6 axis. The recruitment of Th17 cells decreases the number of tumor foci in lungs and attenuates the lung metastasis of melanoma cells in mice.

CONCLUSIONS

The results provide new information on the role and mechanisms of action of probiotics in attenuating extra-intestinal tumor metastasis.

S1PR1 as a Novel Promising Therapeutic Target in Cancer Therapy

Sphingosine-1-phosphate (S1P) can regulate several physiological and pathological processes. S1P signaling via its cell surface receptor S1PR1 has been shown to enhance tumorigenesis and stimulate growth, expansion, angiogenesis, metastasis, and survival of cancer cells. S1PR1-mediated tumorigenesis is supported and amplified by activation of downstream effectors including STAT3, interleukin-6, and NF-κB networks. S1PR1 signaling can also trigger various other signaling pathways involved in carcinogenesis including activation of PI3K/AKT, MAPK/ERK1/2, Rac, and PKC/Ca, as well as suppression of cyclic adenosine monophosphate (cAMP). It also induces immunological tolerance in the tumor microenvironment, while the immunosuppressive function of S1PR1 can also lead to the generation of pre-metastatic niches. Some tumor cells upregulate S1PR1 signaling pathways, which leads to drug resistant cancer cells, mainly through activation of STAT3. This signaling pathway is also implicated in some inflammatory conditions leading to the instigation of inflammation-driven cancers. Furthermore, it can also increase survival via induction of anti-apoptotic pathways, for instance, in breast cancer cells. Therefore, S1PR1 and its signaling pathways can be considered as potential anti-tumor therapeutic targets, alone or in combination therapies. Given the oncogenic nature of S1PR1 and its distribution in a variety of cancer cell types along with its targeting advantages over other molecules of this family, S1PR1 should be considered a favorable target in therapeutic approaches to cancer. This review describes the role of S1PR1 in cancer development and progression, specifically addressing breast cancer, glioma, and hematopoietic malignancies. We also discuss the potential use of S1P signaling modulators as therapeutic targets in cancer therapy.

Acid sphingomyelinase regulates TH 2 cytokine release and bronchial asthma

BACKGROUND

Allergic diseases and especially allergic asthma are widespread diseases with high prevalence in childhood, but also in adults. Acid sphingomyelinase (ASM) is a key regulator of the sphingolipid pathway. Previous studies defined the association of ASM with the pathogenesis of T_H 1-directed lung diseases like cystic fibrosis and acute lung injury. Here, we define the role of ASM in T_H 2-regulated allergic bronchial asthma.

METHODS

To determine the role of Asm under baseline conditions, wild-type (WT) and Asm^-/- mice were ventilated with a flexiVent setup and bronchial hyperresponsiveness was determined using acetylcholine. Flow cytometry and cytokine measurements in bronchoalveolar lavage fluid and lung tissue were followed by in vitro T_H 2 differentiations with cells from WT and Asm^-/- mice and blockade of Asm with amitriptyline. As proof of principle, we conducted an ovalbumin-induced model of asthma in WT- and Asm^-/-  mice.

RESULTS

At baseline, Asm^-/- mice showed better lung mechanics, but unaltered bronchial hyperresponsiveness. Higher numbers of Asm^-/- T cells in bronchoalveolar lavage fluid released lower levels of IL-4 and IL-5, and these results were paralleled by decreased production of typical T_H 2 cytokines in Asm^-/- T lymphocytes in vitro. This phenotype could be imitated by incubation of T cells with amitriptyline. In the ovalbumin asthma model, Asm^-/- animals were protected from high disease activity and showed better lung functions and lower levels of eosinophils and T_H 2 cytokines.

CONCLUSION

Asm deficiency could induce higher numbers of T_H 2 cells in the lung, but those cells release decreased T_H 2 cytokine levels. Hereby, Asm^-/- animals are protected from bronchial asthma, which possibly offers novel therapeutic strategies, for example, with ASM blockade.

Chitinase-like protein YKL-40 regulates human bronchial epithelial cells proliferation, apoptosis, and migration through TGF-β1/Smads pathway

In order to study the effects of chitinase-like protein YKL-40 on proliferation, apoptosis, and migration of human bronchial epithelial cell line (BEAS-2B), and the underlying mechanisms, we cultured BEAS-2B alone or with different concentrations of YKL-40. thiazolyl blue tetrazolium bromide (MTT) assay was used to examine the cell proliferation. Annexin V-fluorescein isothiocyanate isomer (FITC)/propidium iodide staining and scratch assay were performed to test the cell apoptosis and migration. The concentrations of transforming growth factor-β1 (TGF-β1), Smad3, Smad7, alpha-smooth muscle actin (α-SMA), interleukin-4 (IL-4), IL-6, and IL-8 in the cell culture supernatant were detected by enzyme-linked immunosorbent assay. The messenger RNA and protein levels of YKL-40, TGF-β1, Smad3, Smad7, and α-SMA were detected by reverse transcription polymerase chain reaction and Western blot. BEAS-2B cells cultured with different concentrations of YKL-40 showed significantly higher cell proliferation and migration and inflammatory cytokines compared with that of control group, while the cell apoptosis was significantly lower than that of control group (p < 0.05). In addition, BEAS-2B cells cultured with YKL-40 had increased TGF-β1, Smad3, Smad7, and α-SMA levels in the supernatant, compared with that of BEAS-2B cells cultured alone (p < 0.05). Furthermore, LY364947, as TGF-β1/Smads signaling pathway inhibitor, decreased cell proliferation and migration ability and enhanced cell apoptosis of BEAS-2B cells compared with control group (p < 0.05). However, YKL-40 administration reversed the effect of LY364947 on the biological behavior of BEAS-2B cells. YKL-40 could affect the biological behaviors of BEAS-2B cells, which might be related to the TGF-β1/Smads pathway.