15-Deoxy-Δ(12,14)-prostaglandin J2 (15d-PGJ2) promotes apoptosis of HBx-positive liver cells

Cyclopentenone Prostaglandins: Biologically Active Lipid Mediators Targeting Inflammation

Cyclopentenone prostaglandins (cyPGs) are biologically active lipid mediators, including PGA2, PGA1, PGJ2, and its metabolites. cyPGs are essential regulators of inflammation, cell proliferation, apoptosis, angiogenesis, cell migration, and stem cell activity. cyPGs biologically act on multiple cellular targets, including transcription factors and signal transduction pathways. cyPGs regulate the inflammatory response by interfering with NF-κB, AP-1, MAPK, and JAK/STAT signaling pathways via both a group of nuclear receptor peroxisome proliferator-activated receptor-gamma (PPAR-γ) dependent and PPAR-γ independent mechanisms. cyPGs promote the resolution of chronic inflammation associated with cancers and pathogen (bacterial, viral, and parasitic) infection. cyPGs exhibit potent effects on viral infections by repressing viral protein synthesis, altering viral protein glycosylation, inhibiting virus transmission, and reducing virus-induced inflammation. We summarize their anti-proliferative, pro-apoptotic, cytoprotective, antioxidant, anti-angiogenic, anti-inflammatory, pro-resolution, and anti-metastatic potential. These properties render them unique therapeutic value, especially in resolving inflammation and could be used in adjunct with other existing therapies. We also discuss other α, β -unsaturated carbonyl lipids and cyPGs like isoprostanes (IsoPs) compounds.

Eicosanoids

This article describes the pathways of eicosanoid synthesis, eicosanoid receptors, the action of eicosanoids in different physiological systems, the roles of eicosanoids in selected diseases, and the major inhibitors of eicosanoid synthesis and action. Eicosanoids are oxidised derivatives of 20-carbon polyunsaturated fatty acids (PUFAs) formed by the cyclooxygenase (COX), lipoxygenase (LOX) and cytochrome P450 (cytP450) pathways. Arachidonic acid (ARA) is the usual substrate for eicosanoid synthesis. The COX pathways form prostaglandins (PGs) and thromboxanes (TXs), the LOX pathways form leukotrienes (LTs) and lipoxins (LXs), and the cytP450 pathways form various epoxy, hydroxy and dihydroxy derivatives. Eicosanoids are highly bioactive acting on many cell types through cell membrane G-protein coupled receptors, although some eicosanoids are also ligands for nuclear receptors. Because they are rapidly catabolised, eicosanoids mainly act locally to the site of their production. Many eicosanoids have multiple, sometimes pleiotropic, effects on inflammation and immunity. The most widely studied is PGE2. Many eicosanoids have roles in the regulation of the vascular, renal, gastrointestinal and female reproductive systems. Despite their vital role in physiology, eicosanoids are often associated with disease, including inflammatory disease and cancer. Inhibitors have been developed that interfere with the synthesis or action of various eicosanoids and some of these are used in disease treatment, especially for inflammation.

Remarkable metabolic reorganization and altered metabolic requirements in frog metamorphic climax

Background

Metamorphic climax is the crucial stage of amphibian metamorphosis responsible for the morphological and functional changes necessary for transition to a terrestrial habitat. This developmental period is sensitive to environmental changes and pollution. Understanding its metabolic basis and requirements is significant for ecological and toxicological research. Rana omeimontis tadpoles are a useful model for investigating this stage as their liver is involved in both metabolic regulation and fat storage.

Results

We used a combined approach of transcriptomics and metabolomics to study the metabolic reorganization during natural and T3-driven metamorphic climax in the liver and tail of Rana omeimontis tadpoles. The metabolic flux from the apoptotic tail replaced hepatic fat storage as metabolic fuel, resulting in increased hepatic amino acid and fat levels. In the liver, amino acid catabolism (transamination and urea cycle) was upregulated along with energy metabolism (TCA cycle and oxidative phosphorylation), while the carbohydrate and lipid catabolism (glycolysis, pentose phosphate pathway (PPP), and β-oxidation) decreased. The hepatic glycogen phosphorylation and gluconeogenesis were upregulated, and the carbohydrate flux was used for synthesis of glycan units (e.g., UDP-glucuronate). In the tail, glycolysis, β-oxidation, and transamination were all downregulated, accompanied by synchronous downregulation of energy production and consumption. Glycogenolysis was maintained in the tail, and the carbohydrate flux likely flowed into both PPP and the synthesis of glycan units (e.g., UDP-glucuronate and UDP-glucosamine). Fatty acid elongation and desaturation, as well as the synthesis of bioactive lipid (e.g., prostaglandins) were encouraged in the tail during metamorphic climax. Protein synthesis was downregulated in both the liver and tail. The significance of these metabolic adjustments and their potential regulation mechanism are discussed.

Conclusion

The energic strategy and anabolic requirements during metamorphic climax were revealed at the molecular level. Amino acid made an increased contribution to energy metabolism during metamorphic climax. Carbohydrate anabolism was essential for the body construction of the froglets. The tail was critical in anabolism including synthesizing bioactive metabolites. These findings increase our understanding of amphibian metamorphosis and provide background information for ecological, evolutionary, conservation, and developmental studies of amphibians.

2,5-dimethylcelecoxib improves immune microenvironment of hepatocellular carcinoma by promoting ubiquitination of HBx-induced PD-L1

Background

2,5-dimethylcelecoxib (DMC) is a targeted inhibitor of microsomal prostaglandin E synthase-1 (mPGES-1), a key enzyme in the PGE2 synthesis pathway of inflammatory mediators. Previous studies have confirmed that DMC can inhibit the growth of hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC). However, it is not known whether DMC is involved in the changes of tumor immune microenvironment.

Methods

In this study, we explored the effects of DMC on HBV-related HCC immune microenvironment, and deeply analyzed its unique effect and mechanism on programmed death receptor 1 (PD-1)/and its ligand 1 (PD-L1) pathway.

Results

Clinical hepatoma tissues detection showed that compared with non-virus-related HCC, the level of CD8 of HBV-related HCC was significantly lower, while the levels of PD-L1 and CD163 were higher. In vivo experiments indicated that DMC could increase the level of tumor infiltrating CD8⁺ T cells in hepatitis B virus X (HBx) (+) hepatoma cells implanted mouse models, and inhibit the expression of PD-L1 and CD163 in tumor tissues. DMC combined with atezolizumab had more significant antitumor effect and stronger blocking effect on PD-1/PD-L1 pathway. Mechanism studies have shown that DMC can promote ubiquitin degradation of HBx-induced PD-L1 protein in HCC cells by activating adenosine 5′-monophosphate-activated protein kinase pathway. Further experiments confirmed that this process was mainly mediated by E3 ligase RBX1.

Conclusions

Our results uncover a role for DMC in promoting HBV-related HCC immune microenvironment, which not only enrich the relationship between inflammatory factors (mPGES-1/PGE2 pathway) and immunosuppression (PD-L1), but also provide an important strategic reference for multitarget or combined immunotherapy of HBV-related HCC.

Hepatitis B virus X protein (HBx) promotes ST2 expression by GATA2 in liver cells

At present, most studies on the relationship between hepatitis B virus (HBV) and IL-33/ST2 axis focus on clinical detection, but the underlying molecular mechanisms of HBx and IL-33/ST2 axis regulation and Th cell function regulation have not been explored. In this study, serum samples of patients with chronic hepatitis B (CHB) and HBV-related liver cancer (HBV-HCC), and healthy controls, as well as the supernatant solutions of HL7702-WT, HL7702-NC, and HL7702-HBx cells were collected to detect the content of soluble ST2 (sST2). The contents of Th1 cytokines (TNF-α and TNF-γ) and Th2 cytokines (IL-6 and IL-10) in the supernatant of different co-culture groups were detected. The effects of GATA2 on ST2 promoter transcription were investigated by upregulation or interference with GATA2 expression, dual-luciferase reporting, and ChIP experiments. The combined detection of sST2 and FIB-4 was beneficial to the non-invasive diagnosis of liver fibrosis. HBx promotes sST2 expression in liver cells, upregulates Th2 cell function, and inhibits Th1 cell function through IL-33/ST2 axis. HBx interacts with GATA2 to influence the activity of ST2 promoter. Serum sST2 detection is an invaluable indicator for the assessment of the progress of HBV infectious diseases, and the IL-33/ST2 axis plays an important role in changing the cellular immune function caused by HBV infection.

Generation of induced secretome from adipose-derived stem cells specialized for disease-specific treatment: An experimental mouse model

BACKGROUND

Recently, the exclusive use of mesenchymal stem cell (MSC)-secreted molecules, named as the secretome, have been evaluated for overcoming the limitations of cell-based therapy while maintaining its advantages.

AIM

To improve cell-free therapy by adding disease-specificity through stimulation of MSCs using disease-causing materials.

METHODS

We collected the secretory materials (named as inducers) released from AML12 hepatocytes that had been pretreated with thioacetamide (TAA) and generated the TAA-induced secretome (TAA-isecretome) after stimulating adipose-derived stem cells with the inducers. The TAA-isecretome was intravenously administered to mice with TAA-induced hepatic failure and those with partial hepatectomy.

RESULTS

TAA-isecretome infusion showed higher therapeutic potential in terms of (1) restoring disorganized hepatic tissue to normal tissue; (2) inhibiting proinflammatory cytokines (interleukin-6 and tumor necrosis factor-α); and (3) reducing abnormally elevated liver enzymes (aspartate aminotransferase and alanine aminotransferase) compared to the naïve secretome infusion in mice with TAA-induced hepatic failure. However, the TAA-isecretome showed inferior therapeutic potential for restoring hepatic function in partially hepatectomized mice. Proteomic analysis of TAA-isecretome identified that antioxidant processes were the most predominant enriched biological networks of the proteins exclusively identified in the TAA-isecretome. In addition, peroxiredoxin-1, a potent antioxidant protein, was found to be one of representative components of TAA-isecretome and played a central role in the protection of TAA-induced hepatic injury.

CONCLUSION

Appropriate stimulation of adipose-derived stem cells with TAA led to the production of a secretome enriched with proteins, especially peroxiredoxin-1, with higher antioxidant activity. Our results suggest that appropriate stimulation of MSCs with pathogenic agents can lead to the production of a secretome specialized for protecting against the pathogen. This approach is expected to open a new way of developing various specific therapeutics based on the high plasticity and responsiveness of MSCs.

Expression of programmed cell death1 in T follicular helper cells is regulated by prostaglandin E2 secreted by HBV-infected HepG2.2.1.5 cells

The present study aimed to investigate the distribution of T follicular helper (Tfh)-cell subsets in patients with hepatitis B virus (HBV) and determine the underlying mechanism of HBV regulation of Tfh cells. The frequency of peripheral blood Tfh subsets was analyzed using flow cytometry. The expression level of programmed cell death‑1 (PD‑1) and prostaglandin E2 (PGE2) was quantified using reverse transcription‑quantitative polymerase chain reaction and western blotting. The PGE2 level in culture supernatant was detected using enzyme‑linked immunosorbent assay. A Transwell chamber was used to co‑culture Tfh cells with HepG2 and HepG2.2.1.5. The percentage of inducible T‑cell costimulator (ICOS)+ and total Tfh cells was high at the immune activation (IA) group; however, it was reduced in the immune tolerance (IT), responders with HBsAg seroconversion (RP) and healthy control (HC) groups. The percentage of PD‑1+ Tfh cells was significantly higher in IA and IT compared with RP and HC. The ratio of PD‑1+/total Tfh cells was positively correlated with the load of HBV DNA; therefore, this ratio may act as an indicator for HBV replication. The expression level of PD‑1 in Tfh cells was higher in the HepG2.2.1.5 co‑cultured group compared with the HepG2 group, this may be due to the high PGE2 expression level in HBV‑infected HepG2.2.1.5 cells. The findings of the present study revealed an imbalanced distribution of PD‑1+ Tfh cells in patients with HBV at different immune phases. Additionally, HBV may upregulate the expression of PD‑1 in Tfh cells by promoting HepG2.2.1.5 to secret PGE2. Identifying the effect of HBV on Tfh‑cell subsets is crucial for improving immuno-based therapy for HBV.

Elimination of the biphasic pharmacodynamics of 15d-PGJ2 by controlling its release from a nanoemulsion

15-Deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2) has a dual action of stimulating anti-inflammation and anti-proliferation when exogenously administered at high doses. However, at lower doses, it can be toxic inducing opposite actions, ie, stimulation of both inflammation and cell proliferation. This biphasic phenomenon of 15d-PGJ2 is believed to be due to its multitarget behavior. In this study, we provide a strategy for controlling such biphasic pharmacodynamics by separating its dual actions while retaining the beneficial one by using a nanoemulsion (NE). The 15d-PGJ2 was encapsulated in the NE composed of triolein/distearoyl phosphatidylcholine/Tween 80 at a high encapsulation ratio (>83%). Furthermore, NE enhanced drug retention by slowing down its release rate, which was, unconventionally, inversely dependent on the total surface area of the NE system. Next, focusing on the biphasic effect on cell proliferation, we found that the 15d-PGJ2-loaded slow-release NE showed only a dose-dependent inhibition of the viability of a mouse macrophage cell line, RAW264.7, although a fast-release NE as well as free 15d-PGJ2 exerted a biphasic effect. The observed slow-release kinetics are believed to be responsible for elimination of the biphasic pharmacodynamics of 15d-PGJ2 mainly for two reasons: 1) a high proportion of 15d-PGJ2 that is retained in the NE was delivered to the cytosol, where proapoptotic targets are located and 2) 15d-PGJ2 was able to bypass cell membrane-associated targets that lead to the induction of cellular proliferation. Collectively, our strategy of eliminating the 15d-PGJ2-induced biphasic pharmacodynamics was based on the delivery of 15d-PGJ2 to its desired site of action, excluding undesired sites, on a subcellular level.

15-Deoxy-Δ(12,14)-prostaglandin J2 Induces Apoptosis and Upregulates SOCS3 in Human Thyroid Cancer Cells

The cyclopentenone prostaglandin 15-deoxy-Δ^12,14-prostaglandin J₂ (15d-PGJ₂) is a natural ligand of peroxisome proliferator-activated receptor gamma (PPAR-γ) and a potential mediator of apoptosis in cancer cells. In the present study, we evaluated the effect of 15d-PGJ₂ in human thyroid papillary carcinoma cells (TPC-1) using different doses of 15d-PGJ₂ (0.6 to 20 μM) to determine IC₅₀ (9.3 μM) via the MTT assay. The supernatant culture medium of the TPC-1 cells that was treated either with 15d-PGJ₂ or with vehicle (control) for 24 hours was assessed for IL-6 secretion via CBA assay. RT-qPCR was used to evaluate mRNA expression of IL-6, SOCS1, SOCS3, and STAT3. TPC-1 cells treated with 15d-PGJ₂ decreased the secretion and expression of IL-6 and STAT3, while it increased SOCS1 and SOCS3. Overall, we demonstrated that 15d-PGJ₂ downregulated IL-6 signaling pathway and led TPC-1 cells into apoptosis. In conclusion, 15d-PGJ₂ shows the potential to become a new therapeutic approach for thyroid tumors.

15d-PGJ2 Reduced Microglia Activation and Alleviated Neurological Deficit of Ischemic Reperfusion in Diabetic Rat Model

To investigate the effect of PPARγ agonist 15d-PGJ2 treatment on the microglia activation and neurological deficit of ischemia reperfusion in diabetic rat model, adult Sprague-Dawley rats were sacrificed for the research. The rats were randomly categorized into four groups: (1) sham-operated group; (2) standard ischemia group; (3) diabetic ischemia group; (4) diabetic ischemia group with diabetes and treated with 15d-PGJ2. Compared to the sham-operated group, all the ischemic groups have significantly severer neurological deficits, more TNF-α and IL-1 expression, increased labeling of apoptotic cells, increased CD68 positive staining of brain lesion, and increased volume of infarct and cerebral edema in both 24 hours and 7 days after reperfusion. Interestingly, reduced neurological deficits, decreased TNF-α and IL-1 expression, less apoptotic cells and CD68 positive staining, and alleviated infarct and cerebral edema volume were observed when 15d-PGJ2 was intraperitoneally injected after reperfusion in diabetic ischemia group, suggesting its neuroprotective role in regulating microglia activation, which may have a therapeutic application in the future.