Search Results (112)

Autoimmune hepatitis (AIH) is linked to an increased risk of hepatocellular carcinoma (HCC). However, the precise connection between the two remains unclear. GPR81, a G-protein-coupled receptor located on the membranes of various cell types, plays a role in numerous physiological processes. We established an AIH animal model and activated GPR81 using the agonist 3,5-dihydroxybenzoic acid (3,5-DHBA). Additionally, the effect of GPR81 inhibition on tumor and immune cell dynamics was examined using the HepG2, Hep3B, and Hepa1-6 cell lines with the antagonist 3-hydroxybutyric acid (3-OBA). Our results demonstrated that 3,5-DHBA treatment reduced T cell and pro-inflammatory cytokine secretion, while MDSC secretion increased, inhibiting Concanavalin A (Con A)-induced AIH. The inhibition of GPR81 by 3-OBA suppressed HCC cell proliferation and invasion, reduced tumor volume and weight, and downregulated PD-L1 expression. Furthermore, CTL and DC activity in the spleen and tumors increased, while MDSC activity decreased. This study confirms that GPR81 plays an important role in both inflammation and tumorigenesis, suggesting that GPR81 may serve as a bridge in the transformation of inflammation into cancer. Modulating GPR81 activity may provide a novel therapeutic strategy for hepatitis and cancer. Full article

A series of three 1,3-phenylene bis-oxamides 3a–c, structurally related to the GPR35 receptor-agonist drug lodoxamide, has been synthesized by reacting the 1,3-phenylene bis-oxalamates 2a and 2b with amines. The obtained compounds were characterized by ¹H and ¹³C NMR, and IR spectroscopy, they showed characteristic signals for the aromatic, N―H, and C=O groups. Molecular structure was determined using single-crystal X-ray diffraction. The supramolecular architecture is driven by N―H···O=C, N―H···N, C—H···π, and O=C···O=C interactions depicting a supramolecular helix (3a) and tapes (3b–c). Intermolecular interactions were studied using Hirshfeld surface analysis, where N―H∙∙∙X (X = N, O) hydrogen bonding represents 30.2% to the surface of 3a and 17.8–18.8% to the surface of 3b–c. The most energetic interactions involve the amide N—H∙∙∙O hydrogen bonding, contributing in the −113.9 to −97.0 kJ mol⁻¹ range to the crystal energy, being more dispersive than electrostatic in nature. The molecular docking study was performed to evaluate the binding ability of 3a–c compounds to the GPR35 receptor, showing a favorable binding in a similar way to lodoxamide. Full article

Ketogenesis, a mitochondrial metabolic pathway, occurs primarily in liver, but kidney, colon and retina are also capable of this pathway. It is activated during fasting and exercise, by “keto” diets, and in diabetes as well as during therapy with SGLT2 inhibitors. The principal ketone body is β-hydroxybutyrate, a widely recognized alternative energy source for extrahepatic tissues (brain, heart, muscle, and kidney) when blood glucose is sparse or when glucose transport/metabolism is impaired. Recent studies have identified new functions for β-hydroxybutyrate: it serves as an agonist for the G-protein-coupled receptor GPR109A and also works as an epigenetic modifier. Ketone bodies protect against inflammation, cancer, and neurodegeneration. HMGCS2, as the rate-limiting enzyme, controls ketogenesis. Its expression and activity are regulated by transcriptional and post-translational mechanisms with glucagon, insulin, and glucocorticoids as the principal participants. Loss-of-function mutations occur in HMGCS2 in humans, resulting in a severe metabolic disease. These patients typically present within a year after birth with metabolic acidosis, hypoketotic hypoglycemia, hepatomegaly, steatotic liver damage, hyperammonemia, and neurological complications. Nothing is known about the long-term consequences of this disease. This review provides an up-to-date summary of the biological functions of ketone bodies with a special focus on HMGCS2 in health and disease. Full article

Tumor-associated macrophages (TAMs) in the colorectal cancer (CRC) microenvironment promote tumor progression but can be reprogrammed into a pro-inflammatory state with anti-cancer properties. Activation of the G protein-coupled receptor 84 (GPR84) is associated with pro-inflammatory macrophage polarization, making it a potential target for CRC therapy. This study evaluates the effects of the GPR84 agonists 6-OAU and ZQ-16 on macrophage activation and anti-cancer efficacy. GPR84 expression on THP-1 macrophages and murine BMDMs was analyzed using flow cytometry. Macrophages were treated with 6-OAU or ZQ-16, and pro-inflammatory cytokine levels, reactive oxygen species (ROS) production, and phagocytosis were assessed using qPCR and functional assays. Anti-cancer effects were tested in a subcutaneous MC38 tumor model, with oral or intraperitoneal agonist administration. Pharmacokinetics and compound stability were also evaluated. In THP-1 macrophages, 6-OAU increased pro-inflammatory cytokines and ROS production, with ZQ-16 showing similar effects. However, neither agonist induced pro-inflammatory responses, ROS production, or phagocytosis in murine macrophages. In vivo, both agonists failed to inhibit tumor growth in the MC38 model despite systemic exposure. Current GPR84 agonists lack efficacy in promoting anti-cancer macrophage activity, limiting their potential as CRC therapies. Full article

Gut peptides, including glucagon-like peptide-1 (GLP-1), regulate metabolic homeostasis and have emerged as the basis for multiple state-of-the-art diabetes and obesity therapies. We previously showed that G protein-coupled receptor 17 (GPR17) is expressed in intestinal enteroendocrine cells (EECs) and modulates nutrient-induced GLP-1 secretion. However, the GPR17-mediated molecular signaling pathways in EECs have yet to be fully deciphered. Here, we expressed the human GPR17 long isoform (hGPR17L) in GLUTag cells, a murine EEC line, and we used the GPR17 synthetic agonist MDL29,951 together with pharmacological probes and genetic approaches to quantitatively assess the contribution of GPR17 signaling to GLP-1 secretion. Constitutive hGPR17L activity inhibited GLP-1 secretion, and MDL29,951 treatment further inhibited this secretion, which was attenuated by treatment with the GPR17 antagonist HAMI3379. MDL29,951 promoted both Gi/o and Gq protein coupling to mediate cyclic AMP (cAMP) and calcium signaling. hGPR17L regulation of GLP-1 secretion appeared to be Gq-independent and dependent upon Gi/o signaling, but was not correlated with MDL29,951-induced whole-cell cAMP signaling. Our studies revealed key signaling mechanisms underlying the role of GPR17 in regulating GLP-1 secretion and suggest future opportunities for pharmacologically targeting GPR17 with inverse agonists to maximize GLP-1 secretion. Full article

Cognitive impairment is a core feature of neurodevelopmental (schizophrenia) and aging-associated (mild cognitive impairment and Alzheimer’s dementia) neurodegenerative diseases. Limited efficacy of current pharmacological treatments warrants further search for new targets for nootropic interventions. The breakdown of myelin, a phospholipids axonal sheath that protects the conduction of nerve impulse between neurons, was proposed as a neuropathological abnormality that precedes and promotes the deposition of amyloid-β in neuritic plaques. The present review of the recent literature and our own pre- and clinical data suggest (for the first time) that the anthranilic acid (AA)-induced activation of microglial-expressed G-protein coupled receptor (GPR109A) inhibits cytosolic phospholipase A2 (cPLA2), an enzyme that triggers the degradation of myelin and consequently attenuates cognitive impairment. The present review suggests that the up-regulation of AA formation is a sex-specific compensatory (adaptive) reaction aimed to prevent/treat cognitive impairment. The AA–GPR109A–cPLA2–myelin–cognition cascade suggests new nootropic interventions, e.g., the administration of pegylated kynureninase, an enzyme that catalyzes AA formation from Kynurenine (Kyn), a tryptophane catabolite; pegylated interferon-alpha; central and peripheral Kyn aminotransferase inhibitors that increase availability of Kyn as a substrate for AA formation; and vagus nerve stimulation. The cascade predicts nootropic activity of exogenous GPR109A agonists that were designed and underwent clinical trials (unsuccessful) as anti-dyslipidemia agents. The proposed cascade might contribute to the pathogenesis of cognitive impairment. Data on AA in neurodegenerative disorders are scarce, and the proposed cascade needs further exploration in pre- and clinical studies Full article

Despite the close and clinically confirmed association between depression and overactive bladder, it remains unclear whether this affective disorder is a factor causing overactive bladder or whether overactive bladder is a specific symptom of psychosomatic disorders. This study examined the effects of repeated corticosterone administration on the occurrence of symptoms associated with depression and overactive bladder. Additionally, we examined whether administering TC-G 1008, an antidepressant that selectively activates the GPR39 receptor, could alleviate corticosterone-induced depression-like behavior and detrusor overactivity-related changes in cystometric measurements. We also explored its potential to reverse alterations in various biomarkers associated with both conditions in the serum, urinary bladder, and brain of female rats. The administration of corticosterone (20 mg/kg/day for 14 days) yielded anticipated results, including an increase in the duration of immobility during the forced swim test, alterations in parameters specific to bladder overactivity, a decrease in neurotrophins, and an elevation in pro-inflammatory cytokine levels. Treatment with TC-G 1008 (15 mg/kg/day) alleviated symptoms of both detrusor overactivity and depression, while also restoring the levels of biochemical and cystometric markers to normal ranges. Additionally, antidepressants based on GPR39 agonists could enhance the levels of kynurenic acid in the neuroprotective pathway. These results indicate that the GPR39 agonist receptor might be a promising future therapeutic approach for treating overactive bladder that occurs alongside depression. Full article

Diabetes mellitus (DM) is a common metabolic disease that poses a severe threat to human health. Despite a range of therapeutic approaches, there remains a lack of effective and safe therapies with the existing drugs. Therefore, there is an urgent need to develop novel, effective, and safe therapeutic strategies for DM. Free fatty acid receptor 4 (FFAR4), also known as GPR120, is a member of the G protein-coupled receptor family, which has received considerable attention as an attractive new therapeutic target for treating DM. In the present study, based on the structure of TUG-891, which has excellent activity and selectivity, a series of novel FFAR4 agonists was designed by replacing the phenylpropanoic acid β position carbon atom with an oxygen atom, while replacing the linking oxymethylene with an amide-linking group. The target compounds were evaluated for FFAR4 agonistic activity, and the preferred compounds were evaluated for selectivity, oral glucose tolerance in normal ICR mice, antidiabetic activity in diet-induced obese (DIO) mice, pharmacokinetic properties in ICR mice and molecular modeling studies. The results showed that compound 10f possessed excellent FFAR4 agonistic activity and selectivity, significantly improved glucose tolerance in normal ICR mice, lowered blood glucose and promoted insulin secretion in a dose-dependent manner in DIO mice, and showed favorable pharmacokinetic properties. These results indicate that compound 10f may be a promising compound that deserves further structure–activity relationship and pharmacological studies for the development of antidiabetic drugs. Full article

Pericytes (PCs) contribute to brain capillary/BBB integrity and PC migration is a hallmark for brain capillary leakage following pro-inflammatory insults. Estradiol promotes endothelial barrier integrity by inhibiting tumor necrosis factor-alpha (TNF-α)-induced PC migration. However, the underlying mechanisms remain unclear. Since micro-RNAs (miRs) regulate BBB integrity and increases in miR638 and TNF-α occur in pathological events associated with capillary leakage, we hypothesize that TNF-α mediates its capillary disruptive actions via miR638 and that estradiol blocks these actions. Using quantitative reverse transcription PCR, we first assessed the modulatory effects of TNF-α on miR638. The treatment of PCs with TNF-α significantly induced miR638. Moreover, transfection with miR638 mimic induced PC migration, whereas inhibitory miR638 (anti-miR) abrogated the pro-migratory actions of TNF-α, suggesting that TNF-α stimulates PC migration via miR638. At a molecular level, the pro-migratory effects of miR638 involved the phosphorylation of ERK1/2 but not Akt. Interestingly, estradiol downregulated the constitutive and TNF-α-stimulated expression of miR638 and inhibited the TNF-α-induced migration of PCs. In PCs treated with estrogen receptor (ER) ER-α, ER-β, and GPR30 agonists, a significant downregulation in miR638 expression was solely observed in response to DPN, an ER-β agonist. DPN inhibited the pro-migratory effects of TNF-α but not miR638. Additionally, the ectopic expression of miR638 prevented the inhibitory effects of DPN on TNF-α-induced PC migration, suggesting that interference in miR638 formation plays a key role in mediating the inhibitory actions of estradiol/DPN. In conclusion, these findings provide the first evidence that estradiol inhibits TNF-α-induced PC migration by specifically downregulating miR638 via ER-β and may protect the neurovascular unit during injury/stroke via this mechanism. Full article

Polycystic ovary yndrome (PCOS) is a common metabolic disorder in women, which is usually associated with insulin resistance (IR) and chronic inflammation. Loureirin B (LrB) can effectively improve insulin resistance and alleviate chronic inflammation, and in order to investigate the therapeutic effect of LrB on polycystic ovary syndrome with insulin resistance (PCOS-IR), we conducted animal experiments. A PCOS-IR rat model was established by feeding a high-fat diet combined with letrozole (1 mg/kg·d for 21 days). The rats were treated with the GPR120 agonists TUG-891 and LrB for 4 weeks. Biochemical parameters (fasting blood glucose, total cholesterol, triglycerides, high- and low-density lipoprotein), hormone levels (serum insulin, E2, T, LH, and FSH), and inflammatory cytokines (TNF-α, IL-1β, IL-6, and IL-18) were analyzed. Histopathological analyses of ovaries were performed using hematoxylin/eosin (H&E) staining. Real-time PCR and western blotting were used to assess GPR120, NLRP3, and caspase-1 expression in ovaries, and immunohistochemistry was used to evaluate LKB1 and AMPK protein expression. LrB reduced body weight, Lee’s index, ovarian index, ovarian area, and volume in PCOS-IR rats. It lowered fasting blood glucose, serum insulin, and HOMA-IR. LrB decreased total serum cholesterol, triglyceride, and LDL levels and increased HDL levels. It reduced serum T, LH, and LH/FSH and raised serum E2 and FSH levels. LrB downregulated the mRNA and protein expression levels of NLRP3 and Caspase-1, increased the protein and mRNA expression levels of GPR120 in rat ovaries, and increased LKB1 and AMPK protein expression in ovaries, ameliorating ovarian histopathological changes in PCOS-IR rats. Taken together, LrB upregulated GPR120, LKB1, and AMPK protein expression, downregulated NLRP3 and Caspase-1 protein expression, reduced insulin resistance and chronic inflammation, and ameliorated histopathological changes in ovarian tissues in PCOS rats, suggesting its potential as a treatment for PCOS. Full article

G protein-coupled receptor (GPR)40 and GPR120 are receptors for medium- and long-chain free fatty acids. It has been well documented that GPR40 and GPR120 activation improves metabolic syndrome (MetS) and exerts anti-inflammatory effects. Since chronic periodontitis is a common oral inflammatory disease initiated by periodontal pathogens and exacerbated by MetS, we determined if GPR40 and GPR120 activation with agonists improves MetS-associated periodontitis in animal models in this study. We induced MetS and periodontitis by high-fat diet feeding and periodontal injection of lipopolysaccharide, respectively, and treated mice with GW9508, a synthetic GPR40 and GPR120 dual agonist. We determined alveolar bone loss, osteoclast formation, and periodontal inflammation using micro-computed tomography, osteoclast staining, and histology. To understand the underlying mechanisms, we further performed studies to determine the effects of GW9508 on osteoclastogenesis and proinflammatory gene expression in vitro. Results showed that GW9508 improved metabolic parameters, including glucose, lipids, and insulin resistance. Results also showed that GW9508 improves periodontitis by reducing alveolar bone loss, osteoclastogenesis, and periodontal inflammation. Finally, in vitro studies showed that GW9508 inhibited osteoclast formation and proinflammatory gene secretion from macrophages. In conclusion, this study demonstrated for the first time that GPR40/GPR120 agonist GW9508 reduced alveolar bone loss and alleviated periodontal inflammation in mice with MetS-exacerbated periodontitis, suggesting that activating GPR40/GPR120 with agonist GW9508 is a potential anti-inflammatory approach for the treatment of MetS-associated periodontitis. Full article

The prevalence of obesity-induced asthma increases in women after menopause. We hypothesized that the increase in obese asthma in middle-aged women results from estrogen loss. In particular, we focused on the acute action of estrogen through the G protein-coupled estrogen receptor 1 (GPER), previously known as GPR30. We investigated whether GPER activation ameliorates obesity-induced asthma with a high-fat diet (HFD) using G-1, the GPER agonist, and G-36, the GPER antagonist. Administration of G-1 (0.5 mg/kg) suppressed HFD-induced airway hypersensitivity (AHR), and increased immune cell infiltration, whereas G-36 co-treatment blocked it. Histological analysis showed that G-1 treatment inhibited HFD-induced inflammation, fibrosis, and mucus hypersecretion in a GPER-dependent manner. G-1 inhibited the HFD-induced rise in the mRNA levels of pro-inflammatory cytokines in the gonadal white adipose tissue and lungs, whereas G-36 co-treatment reversed this effect. G-1 increased anti-inflammatory M2 macrophages and inhibited the HFD-induced rise in pro-inflammatory M1 macrophages in the lungs. In addition, G-1 treatment reversed the HFD-induced increase in leptin expression and decrease in adiponectin expression in the lungs and gonadal white adipose tissue. The results suggest that activation of GPER could be a therapeutic option for obesity-induced asthma. Full article

The precise regulation of pH homeostasis is crucial for normal physiology. However, in tissue microenvironments, it can be impacted by pathological conditions such as inflammation and cancer. Due to the overproduction and accumulation of acids (protons), the extracellular pH is characteristically more acidic in inflamed tissues and tumors in comparison to normal tissues. A family of proton-sensing G-protein-coupled receptors (GPCRs) has been identified as molecular sensors for cells responding to acidic tissue microenvironments. Herein, we review the current research progress pertaining to these proton-sensing GPCRs, including GPR4, GPR65 (TDAG8), and GPR68 (OGR1), in inflammation and cancer. Growing evidence suggests that GPR4 and GPR68 are mainly pro-inflammatory, whereas GPR65 is primarily anti-inflammatory, in various inflammatory disorders. Both anti- and pro-tumorigenic effects have been reported for this family of receptors. Moreover, antagonists and agonists targeting proton-sensing GPCRs have been developed and evaluated in preclinical models. Further research is warranted to better understand the roles of these proton-sensing GPCRs in pathophysiology and is required in order to exploit them as potential therapeutic targets for disease treatment. Full article

Alzheimer’s disease (AD), a progressive neurodegenerative disorder, manifests through dysregulation of brain function and subsequent loss of bodily control, attributed to β-amyloid plaque deposition and TAU protein hyperphosphorylation and aggregation, leading to neuronal death. Concurrently, similar cannabinoids to the ones derived from Cannabis sativa are present in the endocannabinoid system, acting through receptors CB₁R and CB₂R and other related receptors such as Trpv-1 and GPR-55, and are being extensively investigated for AD therapy. Given the limited efficacy and adverse effects of current available treatments, alternative approaches are crucial. Therefore, this review aims to identify effective natural and synthetic cannabinoids and elucidate their beneficial actions for AD treatment. PubMed and Scopus databases were queried (2014–2024) using keywords such as “Alzheimer’s disease” and “cannabinoids”. The majority of natural (Δ⁹-THC, CBD, AEA, etc.) and synthetic (JWH-133, WIN55,212-2, CP55-940, etc.) cannabinoids included showed promise in improving memory, cognition, and behavioral symptoms, potentially via pathways involving antioxidant effects of selective CB₁R agonists (such as the BDNF/TrkB/Akt pathway) and immunomodulatory effects of selective CB₂R agonists (TLR4/NF-κB p65 pathway). Combining anticholinesterase properties with a cannabinoid moiety may enhance therapeutic responses, addressing cholinergic deficits of AD brains. Thus, the positive outcomes of the vast majority of studies discussed support further advancing cannabinoids in clinical trials for AD treatment. Full article

β-glucans found in cereal grains have been previously demonstrated to improve blood glucose control; however, current understanding points to their high viscosity as the primary mechanism of action. In this work, we present a novel, highly soluble, low-viscosity β-glucan fiber (HS-BG fiber) and a preclinical dataset that demonstrates its impact on two mechanisms related to the prevention of hyperglycemia. Our results show that HS-BG inhibits the activity of two key proteins involved in glucose metabolism, the α-glucosidase enzyme and the SGLT1 transporter, thereby having the potential to slow starch digestion and subsequent glucose uptake. Furthermore, we demonstrate in a multi-donor fecal fermentation model that HS-BG is metabolized by several different members of the gut microbiome, producing high amounts of short-chain fatty acids (SCFAs), known agonists of GPR43 receptors in the gut related to GLP-1 secretion. The production of SCFAs was verified in the translational gut model, SHIME^®. Moreover, HS-BG fiber fermentation produces compounds that restored permeability in disrupted epithelial cells, decreased inflammatory chemokines (CXCL10, MCP-1, and IL-8), and increased anti-inflammatory marker (IL-10), which could improve insulin resistance. Together, these data suggest that the novel HS-BG fiber is a promising new functional ingredient that can be used to modulate postprandial glycemic responses while the high solubility and low viscosity enable easy formulation in both beverage and solid food matrices. Full article