P2Y6 signaling in alveolar macrophages prevents leukotriene-dependent type 2 allergic lung inflammation

Revealing the anti-inflammatory ingredients in wine-processed Radix et Rhizoma Rhei using immobilized cysteinyl leukotriene receptor type 1 as the stationary phase

Despite the tremendous progress of wine-processed Radix et Rhizoma Rhei (Jiudahuang, JDH) in removing toxic heat from the blood in the upper portion of the body for hundreds of years, the deep understanding of its functional material basis of the anti-inflammatory ingredients remains unclear due to the lack of high specific and efficient methods. Herein, taking Cysteinyl leukotriene receptor type 1(CysLT1R) as the target protein, we established a chromatographic method based on the immobilized CysLT1R using haloalkane dehalogenases (Halo) at the C-terminus of the receptor in one step. After careful characterization by X-ray photoelectronic spectroscopy, immune-fluorometric analysis, and chromatographic investigations, the immobilized receptor was used to screen the anti-inflammatory ingredients in JDH. Aloe-emodin, rhein, emodin, chrysophanol, and physcion were identified as the main anthraquinone exerting anti-inflammatory effects in the drug. The association constants for the five compounds to bind with the receptor were calculated as (0.30 ± 0.06)× 105, (0.35 ± 0.03)× 105, (0.46 ± 0.05)× 105, (1.05 ± 0.14)× 105, and (1.66 ± 0.17)× 105 M-1 by injection amount-dependent method. Meanwhile, hydrogen bonds were identified as the main driving force for the five compounds to bind with CysLT1R by molecular docking. Based on these results, we believe that the immobilized receptor chromatography preserves historic significance in revealing the functional material basis of the complex matrices.

Lack of S1PR2 in Macrophage Ameliorates Sepsis-associated Lung Injury through Inducing IL-33-mediated Type 2 Immunity

The function of type 2 immunity and mechanisms underlying the initiation of type 2 immunity after sepsis-induced lung injury remain unclear. Sphingosine-1-phosphate receptor 2 (S1PR2) has been demonstrated to modulate type 2 immunity in the context of asthma and pulmonary fibrosis. Thus, this study aims to investigate the role of type 2 immunity and whether and how S1PR2 regulates type 2 immunity in sepsis. Peripheral type 2 immune responses in patients with sepsis and healthy control subjects were assessed. The impact of S1PR2 on type 2 immunity in patients with sepsis and in a murine model of sepsis was further investigated. The type 2 innate immune responses were significantly increased in the circulation of patients 24 hours after sepsis, which was positively related to clinical complications and negatively correlated with S1PR2 mRNA expression. Animal studies showed that genetic deletion or pharmacological inhibition of S1PR2 induced type 2 innate immunity accumulation in the post-septic lungs. Mechanistically, S1PR2 deficiency promoted macrophage-derived interleukin (IL)-33 increase and the associated type 2 response in the lung. Furthermore, S1PR2-regulated IL-33 from macrophages mitigated lung injury after sepsis in mice. In conclusion, a lack of S1PR2 modulates the type 2 immune response by upregulating IL-33 release from macrophages and alleviates sepsis-induced lung injury. Targeting S1PR2 may have potential therapeutic value for sepsis treatment.

Pyrimidinergic receptor P2Y6 expression is elevated in lung adenocarcinoma and is associated with poor prognosis

BACKGROUD

Previous in vitro studies have indicated that pyrimidinergic receptor P2Y6 (P2RY6, P2Y6 receptor) may function as a cancer-promoting factor in lung adenocarcinoma (LUAD). However, the prognostic significance of P2RY6 expression in LUAD has not been investigated.

OBJECTIVE

This study aimed to assess the impact of P2RY6 expression on the survival of patients with LUAD.

METHODS

First, we assessed P2RY6 mRNA and protein expression in LUAD and non-cancerous lung tissues using the online bioinformatics analysis tool GEPIA, fresh LUAD tissues, and LUAD tissue microarrays (TMAs). Second, we investigated the correlation between P2RY6 expression and clinicopathological parameters of LUAD patients based on data from The Cancer Genome Atlas (TCGA) database and TMAs. Finally, we analyzed the prognostic significance of P2RY6 expression in LUAD using the online survival analysis tool Kaplan-Meier Plotter and data from TMAs.

RESULTS

We demonstrated that P2RY6 mRNA and protein expression levels in LUAD tissues were significantly higher than those in non-cancerous lung tissues. The expression of P2RY6 in LUAD was positively correlated with poor differentiation, more lymph node metastasis, and more advanced clinical stage. Higher P2RY6 expression level was correlated with shorter survival of the LUAD patients. Univariate and multivariate Cox regression analyses indicated that higher P2RY6 tumor expression was an independent unfavorable prognostic factor for LUAD patients.

CONCLUSIONS

P2RY6 expression was elevated in LUAD and correlated with poor prognosis.

Macrophage P2Y6 Receptor Signaling Selectively Activates NFATC2 and Suppresses Allergic Lung Inflammation

Innate immune responses to innocuous Ags can either prevent or facilitate adaptive type 2 allergic inflammation, but the mechanisms are incompletely understood. We now demonstrate that macrophage UDP-specific type 6 purinergic (P2Y6) receptors selectively activate NFATC2, a member of the NFAT family, to drive an innate IL-12/IFN-γ axis that prevents type 2 allergic inflammation. UDP priming potentiated IL-12p40 production in bone marrow-derived macrophages (BMMs) stimulated by the house dust mite Dermatophagoides farinae (Df) in a P2Y6-dependent manner. Inhibitions of phospholipase C, calcium increase, and calcineurin eliminated UDP-potentiated Df-induced IL-12p40 production. UDP specifically induced nuclear translocation of NFATC2, but not NFATC1 and NFATC3, in BMMs in a P2Y6-dependent manner. UDP-potentiated IL-12p40 production by BMMs and Df-induced IL-12p40 gene expression by alveolar macrophages were abrogated in cells from Nfatc2 knockout mice. Pulmonary transplantation of wild-type but not Nfatc2 knockout macrophages increased Df-induced IL-12 production and IFN-γ expression in P2ry6 fl/fl/Cre/+ recipient mice. Finally, Nfatc2 knockout mice showed significantly increased indices of type 2 immunopathology in response to Df challenge, similar to P2ry6 fl/fl/Cre/+ mice. Thus, macrophage P2Y6 receptor signaling selectively utilizes NFATC2 to potentiate an innate IL-12/IFN-γ axis, a potential mechanism that protects against inappropriate type 2 immune responses.

Inhibition of P2Y6 receptor expression in Kupffer cells alleviates alcoholic steatohepatitis in mice

Inflammation plays an important role in the progression of alcohol-related liver disease (ALD). UDP-P2Y₆ signaling is involved in many human diseases. The purinergic P2Y₆ receptor, an important regulator of inflammation and phagocytosis, has attracted attention, but its role in alcoholic steatohepatitis remains unclear. Here, we found that P2Y₆ levels were significantly elevated in Kupffer cells in the livers of mice with alcoholic steatohepatitis and ethanol (EtOH)-induced RAW264.7 cells. In this study, mice with alcoholic steatohepatitis were intraperitoneally injected with MRS2578, a specific inhibitor of the P2Y₆ receptor, and P2Y₆ was silenced in EtOH-induced RAW264.7 cells. We found a marked improvement in steatosis and inflammation in the livers of mice with alcoholic steatohepatitis and EtOH-induced RAW264.7 cells. However, P2Y₆ activation in vivo and overexpression in vitro showed contrasting results. In addition, the expression of phospho-p38 mitogen-activated protein kinase (p-p38 MAPK), a phosphorylated protein in the p38 MAPK signaling pathway, was significantly altered after P2Y₆ silencing or overexpression in vitro. P2Y₆ can induce the activation of the p38 MAPK signaling pathway by mediating the calcium influx, whereas inhibition of the expression of P2Y₆ can block the inflammatory process to some extent and thus improve the inflammatory response. The results of this study suggested that targeting P2Y₆ signaling may be a potentially effective strategy for the treatment of alcoholic steatohepatitis.

P2RY6 has a critical role in mouse skin carcinogenesis by regulating the YAP and β-catenin signaling pathways

P2Y purinoceptor 6 (P2RY6) is highly expressed in skin keratinocytes, but its function in skin diseases is unclear. We use two-step chemical induction method to induce mouse skin tumor formation. Multiple in vitro and in vivo assays were used to explore the role of P2RY6 in skin tumor. We report that P2ry6-deficient mice exhibit marked resistance to DMBA/TPA-induced skin papilloma formation compared with wild-type mice. Consistent with these findings, epidermal hyperplasia in response to TPA was suppressed in the P2ry6 knockout or MRS2578 (P2RY6 antagonist)-treated mice. The dramatic decrease in hyperplasia and tumorigenesis due to P2ry6 disruption was associated with the suppression of TPA-induced keratinocyte proliferation and inflammatory reactions. Notably, P2ry6 deletion prevented the TPA-induced increase in YAP nuclear accumulation and its downstream gene expression in an MST/LATS1-dependent manner. Upon TPA stimulation, enhanced activation of MEK1 and β-catenin were also impaired in P2ry6 knockout primary keratinocytes, tumor tissues or MRS2578-treated HaCaT cells. Moreover, mutual promotion of the YAP and β-catenin signaling pathways was observed in normal skin cells treated with TPA, while P2ry6 deletion could inhibit their crosstalk by regulating MEK1. Thus, P2RY6 is a critical positive regulator of skin tumorigenesis via modulation of the Hippo/YAP and Wnt/β-catenin signaling pathways.

Metabolites Profiling of Melanoma Interstitial Fluids Reveals Uridine Diphosphate as Potent Immune Modulator Capable of Limiting Tumor Growth

Tumor interstitial fluid (TIF) surrounds and perfuses tumors and collects ions, metabolites, proteins, and extracellular vesicles secreted by tumor and stromal cells. Specific metabolites, accumulated within the TIF, could induce metabolic alterations of immune cells and shape the tumor microenvironment. We deployed a metabolomic approach to analyze the composition of melanoma TIF and compared it to the plasma of C57BL6 mice, engrafted or not with B16-melanoma cells. Among the classes of metabolites analyzed, monophosphate and diphosphate nucleotides resulted enriched in TIF compared to plasma samples. The analysis of the effects exerted by guanosine diphosphate (GDP) and uridine diphosphate (UDP) on immune response revealed that GDP and UDP increased the percentage of CD4+CD25+FoxP3- and, on isolated CD4+ T-cells, induced the phosphorylation of ERK, STAT1, and STAT3; increased the activity of NF-κB subunits p65, p50, RelB, and p52; increased the expression of Th1/Th17 markers including IFNγ, IL17, T-bet, and RORγt; and reduced the expression of IL13, a Th2 marker. Finally, we observed that local administrations of UDP in B16-engrafted C57BL6 mice reduced tumor growth and necrotic areas. In addition, UDP-treated tumors showed a higher presence of MHCIIhi tumor-associated macrophage (TAM) and of CD3+CD8+ and CD3+CD4+ tumor-infiltrating T-lymphocytes (TILs), both markers of anti-tumor immune response. Consistent with this, intra-tumoral gene expression analysis revealed in UDP-treated tumors an increase in the expression of genes functionally linked to anti-tumor immune response. Our analysis revealed an important metabolite acting as mediator of immune response, which could potentially represent an additional tool to be used as an adjuvant in cancer immunotherapy.

Baicalin inhibits LPS-induced inflammation in RAW264.7 cells through miR-181b/HMGB1/TRL4/NF-κB pathway

PURPOSE

Inflammation out of control may induce many diseases. Baicalin has certain anti-inflammatory effects, but its mechanism of action is not clear. Therefore, this study was designed to explore a potential mechanism of anti-inflammation.

METHODS

In this study, RAW264.7 cells were induced by 1.0 g/mL lipopolysaccharide (LPS) and then exposed to baicalin at various concentrations (0.1-1.0 μmol/L). Then, we investigated the effect of baicalin in RAW264.7 inflammation models.

RESULTS

In this study, 0.1-1.0 μmol/L baicalin, especially baicalin at 1.0 μmol/L, effectively inhibited the expression of inflammatory factors (TNF-α, IL-1β, IL-6, Cox, and iNOS), decreased the activity of High Mobility Group Box 1 (HMGB1)/Toll-like Receptor 4 (TLR4)/nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathway, and stimulated miR-181b expression. HMGB1 was proved to be negatively regulated by miR-181b. Here, up-regulation of miR-181b or down-regulation of HMGB1 exerted similar effects as baicalin and down-regulated miR-181b reversed the anti-inflammatory effect of baicalin in RAW264.7 inflammation models.

CONCLUSION

Baicalin can inhibit LPS-induced inflammation in RAW264.7 cells via the miR-181b/HMGB1/TRL4/NF-κB pathway.

G protein-coupled purinergic P2Y receptor oligomerization: Pharmacological changes and dynamic regulation

P2Y receptors (P2YRs) are a δ group of rhodopsin-like G protein-coupled receptors (GPCRs) with many essential functions in physiology and pathology, such as platelet aggregation, immune responses, neuroprotective effects, inflammation, and cellular proliferation. Thus, they are among the most researched therapeutic targets used for the clinical treatment of diseases (e.g., the antithrombotic drug clopidogrel and the dry eye treatment drug diquafosol). GPCRs transmit signals as dimers to increase the diversity of signalling pathways and pharmacological activities. Many studies have frequently confirmed dimerization between P2YRs and other GPCRs due to their functions in cardiovascular and cerebrovascular processes in vivo and in vitro. Recently, some P2YR dimers that dynamically balance physiological functions in the body were shown to be involved in effective signal transduction and exert pathological responses. In this review, we summarize the types, pharmacological changes, and active regulators of P2YR-related dimerization, and delineate new functions and pharmacological activities of P2YR-related dimers, which may be a novel direction to improve the effectiveness of medications.

Structure activity relationship of 3-nitro-2-(trifluoromethyl)-2H-chromene derivatives as P2Y6 receptor antagonists

Various 6-alkynyl analogues of a known 3-nitro-2-(trifluoromethyl)-2H-chromene antagonist 3 of the Gq-coupled P2Y6 receptor (P2Y6R) were synthesized using a Sonogashira reaction to replace a 6-iodo group. The analogues were tested in a functional assay consisting of inhibition of calcium mobilization in P2Y6R-expressing astrocytoma cells elicited by native P2Y6R agonist UDP. 6-Ethynyl and 6-cyano groups were installed, and the alkynes were extended through both alkyl and aryl spacers. The most potent antagonists, with IC50 of ~1 µM, were found to be trialkylsilyl-ethynyl 7 and 8 (3-5 fold greater affinity than reference 3), t-butyl prop-2-yn-1-ylcarbamate 14 and p-carboxyphenyl-ethynyl 16 derivatives, and 3 and 8 displayed surmountable antagonism of UDP-induced production of inositol phosphates. Other chain-extended terminal carboxylate derivatives were less potent than the corresponding methyl ester derivatives. Thus, the 6 position in this chromene series is suitable for derivatization with flexibility of substitution, even with sterically extended chains, without losing P2Y6R affinity. However, a 3-carboxylic acid or 3-ester substitution did not serve as a nitro bioisostere, as the affinity was eliminated. These compounds provide additional ligand tools for the underexplored P2Y6R, which is a target for inflammatory, neurodegenerative and metabolic diseases.

Purinergic Receptors in the Airways: Potential Therapeutic Targets for Asthma?

Extracellular ATP functions as a signaling messenger through its actions on purinergic receptors, and is known to be involved in numerous physiological and pathophysiological processes throughout the body, including in the lungs and airways. Consequently, purinergic receptors are considered to be promising therapeutic targets for many respiratory diseases, including asthma. This review explores how online bioinformatics resources combined with recently generated datasets can be utilized to investigate purinergic receptor gene expression in tissues and cell types of interest in respiratory disease to identify potential therapeutic targets, which can then be investigated further. These approaches show that different purinergic receptors are expressed at different levels in lung tissue, and that purinergic receptors tend to be expressed at higher levels in immune cells and at more moderate levels in airway structural cells. Notably, P2RX1, P2RX4, P2RX7, P2RY1, P2RY11, and P2RY14 were revealed as the most highly expressed purinergic receptors in lung tissue, therefore suggesting that these receptors have good potential as therapeutic targets for asthma and other respiratory diseases.

Control of Macrophage Inflammation by P2Y Purinergic Receptors

Macrophages comprise a phenotypically and functionally diverse group of hematopoietic cells. Versatile macrophage subsets engage to ensure maintenance of tissue integrity. To perform tissue stress surveillance, macrophages express many different stress-sensing receptors, including purinergic P2X and P2Y receptors that respond to extracellular nucleotides and their sugar derivatives. Activation of G protein-coupled P2Y receptors can be both pro- and anti-inflammatory. Current examples include the observation that P2Y14 receptor promotes STAT1-mediated inflammation in pro-inflammatory M1 macrophages as well as the demonstration that P2Y11 receptor suppresses the secretion of tumor necrosis factor (TNF)-α and concomitantly promotes the release of soluble TNF receptors from anti-inflammatory M2 macrophages. Here, we review macrophage regulation by P2Y purinergic receptors, both in physiological and disease-associated inflammation. Therapeutic targeting of anti-inflammatory P2Y receptor signaling is desirable to attenuate excessive inflammation in infectious diseases such as COVID-19. Conversely, anti-inflammatory P2Y receptor signaling must be suppressed during cancer therapy to preserve its efficacy.

Modulation of P2Y6R expression exacerbates pressure overload-induced cardiac remodeling in mice

Cardiac tissue remodeling caused by hemodynamic overload is a major clinical outcome of heart failure. Uridine-responsive purinergic P2Y₆ receptor (P2Y₆R) contributes to the progression of cardiovascular remodeling in rodents, but it is not known whether inhibition of P2Y₆R prevents or promotes heart failure. We demonstrate that inhibition of P2Y₆R promotes pressure overload-induced sudden death and heart failure in mice. In neonatal cardiomyocytes, knockdown of P2Y₆R significantly attenuated hypertrophic growth and cell death caused by hypotonic stimulation, indicating the involvement of P2Y₆R in mechanical stress-induced myocardial dysfunction. Unexpectedly, compared with wild-type mice, deletion of P2Y₆R promoted pressure overload-induced sudden death, as well as cardiac remodeling and dysfunction. Mice with cardiomyocyte-specific overexpression of P2Y₆R also exhibited cardiac dysfunction and severe fibrosis. In contrast, P2Y₆R deletion had little impact on oxidative stress-mediated cardiac dysfunction induced by doxorubicin treatment. These findings provide overwhelming evidence that systemic inhibition of P2Y₆R exacerbates pressure overload-induced heart failure in mice, although P2Y₆R in cardiomyocytes contributes to the progression of cardiac fibrosis.