Search Results (34)

Oxidative stress is a key driver of chronic inflammatory diseases. Anodendron affine is a native Formosan plant species in Taiwan that remains largely underexplored phytochemically and bioactivity. To reveal the bioactive constituents and assess its potential as a source of anti-inflammatory antioxidants, we performed bioactivity-guided fractionation and evaluated the inhibition of superoxide anion (O₂^•−) generation in formyl-L-methionyl-L-leucyl-L-phenylalanine-stimulated human neutrophils. Molecular docking simulations were employed to model interactions with Formyl peptide receptor 1 (FPR1) and the Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase complex, including neutrophil cytosol factor 1 (p47phox) and NADPH oxidase 2 (NOX2), to propose a theoretical mechanism of action. Phytochemical investigation led to the isolation of two new compounds, methyl 4,5-O-diferuloyl-3-methoxyquinate (1) and 16-pregnen-3,12,20-trione (2), together with four known compounds. Notably, 4-hydroxy-3-prenylbenzoic acid (5) exhibited potent inhibitory activity (IC₅₀ = 17.65 ± 0.97 μM), surpassing the activity of the positive control, ibuprofen (IC₅₀ = 27.85 ± 3.56 μM). Docking studies suggested that anodendrosin H (4) and 4-hydroxy-3-prenylbenzoic acid (5) exhibit high predicted binding affinity to p47phox and NOX2. Based on these results, compounds 1, 4, and 5 from A. affine were identified as potential lead candidates for the development of novel anti-inflammatory therapeutics. Full article

Objectives: Periodontitis is a multifactorial inflammatory disease initiated by pathogenic bacteria, such as Porphyromonas gingivalis. Resolvin D1 (RvD1) plays a pivotal role in inflammation resolution. This study aimed to identify the mechanism of the regulatory effects of RvD1 on the inflammatory response of human periodontal ligament cells (hPDLCs). Methods: To investigate the mechanism of RvD1’s impact on the hPDLCs, RNA-sequencing (RNA-seq) was used and differentially expressed genes (DEGs) were identified. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed to assess the signaling pathways in which NF-κB and MAPK were determined to play a significant role. Alterations in NF-κB and MAPK pathways were verified by immunofluorescence (IF), quantitative real-time PCR (qRT-PCR), and Western blotting (WB). The expression of RvD1 and lipoxin A4/formyl peptide receptor 2 (ALX/FPR2) was assessed by IF and WB. Inflammatory cytokine interleukin (IL) 6 and IL-1β release was measured by ELISA. Results: GO and KEGG analyses indicated that RvD1 regulates the inflammatory process in PDLCs primarily via TLR4-MyD88-mediated NF-κB and MAPK signaling. RvD1 suppressed lipopolysaccharide (LPS)-induced TLR4 and MyD88 expression, inhibited phosphorylation of NF-κB p65 and its inhibitor IKBKB, and attenuated phosphorylation of p38 MAPK, ERK, and JNK. ALX/FPR2 was expressed on hPDLCs and was further upregulated upon treatment with RvD1. RvD1 significantly down-regulated the IL-6 and IL-1β levels in LPS-stimulated hPDLCs. Conclusions: RvD1 regulates the inflammatory response of LPS-stimulated hPDLCs by the TLR4-MyD88-MAPK and TLR4-MyD88-NF-κB signaling pathways, suggesting the potential role of RvD1 in restoring periodontal tissue homeostasis by regulating PDLC response to inflammatory and infectious stimuli. Full article

Crotoxin (CTX), the main toxin in Crotalus durissus terrificus venom, is a heterodimeric complex known for its antitumoral, anti-inflammatory, and immunomodulatory properties. In macrophages, CTX stimulates energy metabolism, pro-inflammatory cytokines, superoxide production, and lipoxin A₄ secretion while inhibiting macrophage spreading and phagocytosis. These effects are completely blocked by Boc-2, a selective formyl peptide receptors (FPRs) antagonist. Despite the correlation between FPRs and CTX-mediated effects, their involvement in mediating CTX entry into macrophages remains unclear. This study aimed to investigate the involvement of FPRs in CTX entry into monocytes and macrophages. For this, THP-1 cells were silenced for FPRs or treated with Boc-2. Results demonstrated that FPR-related signaling pathways, which influence macrophage functions such as ROS release, phagocytosis, and spreading, were reduced in FPR-silenced cells. However, even in the absence of FPRs, CTX was efficiently internalized by macrophages. These findings suggest that FPRs are essential for the immunomodulatory effects of CTX, but are not involved in CTX internalization. Full article

Chronic neuroinflammation and oxidative stress play an important role in the onset and progression of neurodegenerative disorders, including Alzheimer’s disease, which can ultimately lead to neuronal damage and loss. The mechanisms of sustained neuroinflammation and the coordinated chain of events that initiate, modulate, and then lead to the resolution of inflammation are increasingly being elucidated, offering alternative approaches for treating pathologies with underlying chronic neuroinflammation. Here, we propose a new multitarget approach to address chronic neuroinflammation and oxidative stress in neurodegenerative disorders by activating the formyl peptide receptor 2 (FPR2) combined with the potentiation of hydrogen sulfide (H₂S) release. FPR2 is a key player in the resolution of inflammation because it mediates the effects of several endogenous pro-resolving mediators. At the same time, H₂S is an endogenous gaseous transmitter with anti-inflammatory and pro-resolving properties, and it can protect against oxidative stress. Starting from potent FPR2 agonists identified in our laboratories, we prepared hybrid compounds by embedding an H₂S-donating moiety within the molecular scaffold of these FPR2 agonists. Following this approach, we identified several compounds that combined potent FPR2 agonism with the ability to release H₂S. The release of H₂S was assessed in buffer and intracellularly. Compounds 7b and 8b combined potent FPR2 agonist activity, selectivity over FPR1, and the ability to release H₂S. Compounds 7b and 8b were next studied in murine primary microglial cells stimulated with lipopolysaccharide (LPS), a widely accepted in vitro model of neuroinflammation. Both compounds were able to counterbalance LPS-induced cytotoxicity and the release of pro-inflammatory (IL-18, IL-6) and anti-inflammatory (IL-10) cytokines induced by LPS stimulation. Full article

The acute phase response is a hallmark of all inflammatory reactions and acute phase reactants, such as C-reactive protein (CRP) and serum amyloid A (SAA) proteins, are among the most useful plasma and serum markers of inflammation in clinical medicine. Although it is well established that inflammatory cytokines, mainly interleukin-1 (IL-1), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) induce SAA in the liver, the biological functions of elicited SAA remain an enigma. By the classical multi-step protein purification studies of chemotactic factors present in plasma or serum, we discovered novel chemokines and SAA1 fragments, which are induced during inflammatory reactions. In contrast to earlier literature, pure SAA1 fails to induce chemokines, an ascribed function that most probably originates from contaminating lipopolysaccharide (LPS). However, intact SAA1 and fragments thereof synergize with CXC and CC chemokines to enhance chemotaxis. Natural SAA1 fragments are generated by inflammatory proteinases such as matrix metalloproteinase-9 (MMP-9). They mediate synergy with chemokines by the interaction with cognate G protein-coupled receptors (GPCRs), formyl peptide receptor 2 (FPR2) and (CC and CXC) chemokine receptors. In conclusion, SAA1 enforces the action of many chemokines and assists in local leukocyte recruitment, in particular, when the concentrations of specifically-induced chemokines are still low. Full article

Sex differences are a complex and crucial variable in developing and progressing metabolic and cardiovascular disease pathophysiology and clinical outcomes. The female sex, compared to the male sex, is protected from metabolic disturbances and their resulting cardiovascular events. However, the peculiar life phases associated with females, such as puberty, pregnancy, and premenopausal and menopausal stages, are all associated with different risks for the development of cardiovascular disease (CVD). Metabolic dysfunction-associated steatotic liver disease (MASLD), a condition of hepatic steatosis, and at least one feature of metabolic syndrome is associated with an increased risk of cardiovascular events. The risk of MASLD and its progression to the development of CVD differs between men and women. Differences in several factors, including formyl peptide receptor (FPR) 2, adipose tissue distribution, liver pyruvate kinase (LPK), and ketone body production, may underlie the sex differences in the risk of development of MASLD-induced CVD. Understanding the specific risk factors involved in the development and progression of MASLD between the sexes is crucial. This knowledge will provide important insights into the mechanisms responsible for its cardiovascular complications and can potentially lead to therapeutics targeted explicitly for each sex, offering new hope in the fight against MASLD-induced CVD. Full article

Alcohol-associated liver disease (ALD) is a prevalent medical problem with limited effective treatment strategies. Although many biological processes contributing to ALD have been elucidated, a complete understanding of the underlying mechanisms is still lacking. The current study employed a proteomic approach to identify hepatic changes resulting from ethanol (EtOH) consumption and the genetic ablation of the formyl peptide receptor 2 (FPR2), a G-protein coupled receptor known to regulate multiple signaling pathways and biological processes, in a mouse model of ALD. Since previous research from our team demonstrated a notable reduction in hepatic FPR2 protein levels in patients with alcohol-associated hepatitis (AH), the proteomic changes in the livers of Fpr2^−/− EtOH mice were compared to those observed in patients with AH in order to identify common hepatic proteomic alterations. Several pathways linked to exacerbated ALD in Fpr2^−/− EtOH mice, as well as hepatic protein changes resembling those found in patients suffering from AH, were identified. These alterations included decreased levels of coagulation factors F2 and F9, as well as reduced hepatic levels of glutamate-cysteine ligase catalytic subunit (GCLC) and total glutathione in Fpr2^−/− EtOH compared to WT EtOH mice. In conclusion, the data suggest that FPR2 may play a regulatory role in hepatic blood coagulation and the antioxidant system, both in a pre-clinical model of ALD and in human AH, however further experiments are required to validate these findings. Full article

Cancer cells exhibit high levels of oxidative stress and consequently require a high amount of cysteine for glutathione synthesis. Solute Carrier Family 7 Member 11 (SLC7A11), or xCT, mediates the cellular uptake of cystine in exchange for intracellular glutamate; imported extracellular cystine is reduced to cysteine in the cytosol through a NADPH-consuming reduction reaction. SLC7A11/xCT expression is under the control of stress-inducing conditions and of several transcription factors, such as NRF2 and ATF4. Formyl-peptide receptor 2 (FPR2) belongs to the FPR family, which transduces chemotactic signals mediating either inflammatory or anti-inflammatory responses according to the nature of its ligands and/or FPR2 binding with other FPR isoforms. The repertoire of FPR2 agonists with anti-inflammatory activities comprises WKYMVm peptide and Annexin A1 (ANXA1), and the downstream effects of the intracellular signaling cascades triggered by FPR2 include NADPH oxidase (NOX)-dependent generation of reactive oxygen species. Herein, we demonstrate that stimulation of CaLu-6 cells with either WKYMVm or ANXA1: (i) induces the redox-regulated activation of SLC7A11/xCT; (ii) promotes the synthesis of glutathione; (iii) prevents lipid peroxidation; and (iv) favors NRF2 nuclear translocation and activation. In conclusion, our overall results demonstrate that FPR2 agonists and NOX modulate SLC7A11/xCT expression and activity, thereby identifying a novel regulative pathway of the cystine/glutamate antiport that represents a new potential therapeutical target for the treatment of human cancers. Full article

Phospholipases (PL) A₂ catalyzes the hydrolysis of membrane phospholipids and mostly generates arachidonic acid (AA). The enzyme 5-lipoxygenase (5-LOX) can metabolize AA to obtain inflammatory leukotrienes, whose biosynthesis highly depends on cPLA2 and 5-LOX activities. Formyl Peptide Receptor 2 (FPR2) belongs to a subfamily of class A GPCRs and is considered the most versatile FPRs isoform. Signaling triggered by FPR2 includes the activation of several downstream kinases and NADPH oxidase (NOX)-dependent ROS generation. In a metabolomic analysis we observed a significant increase in AA concentration in FPR2-stimulated lung cancer cell line CaLu-6. We analyzed cPLA2 phosphorylation and observed a time-dependent increase in cPLA2 Ser505 phosphorylation in FPR2-stimulated cells, which was prevented by the MEK inhibitor (PD098059) and the p38MAPK inhibitor (SB203580) and by blocking NOX function. Similarly, we demonstrated that phosphorylation of 5-LOX at Ser271 and Ser663 residues requires FPR2-dependent p38MAPK and ERKs activation. Moreover, we showed that 5-LOX Ser271 phosphorylation depends on a functional NOX expression. Our overall data demonstrate for the first time that FPR2-induced ERK- and p38MAPK-dependent phosphorylation/activation of cPLA2 and 5-LOX requires a functional NADPH oxidase. These findings represent an important step towards future novel therapeutic possibilities aimed at resolving the inflammatory processes underlying many human diseases. Full article

Neuroinflammation driven primarily by microglia directly contributes to neuronal death in many neurodegenerative diseases. Classical anti-inflammatory approaches aim to suppress pro-inflammatory mediator production, but exploitation of inflammatory resolution may also be of benefit. A key driver of peripheral inflammatory resolution, formyl peptide receptor 2 (Fpr2), is expressed by microglia, but its therapeutic potential in neurodegeneration remains unclear. Here, we studied whether targeting of Fpr2 could reverse inflammatory microglial activation induced by the potent bacterial inflammogen lipopolysaccharide (LPS). Exposure of murine primary or immortalised BV2 microglia to LPS triggered pro-inflammatory phenotypic change and activation of ROS production, effects significantly attenuated by subsequent treatment with the Fpr2 agonist C43. Mechanistic studies showed C43 to act through p38 MAPK phosphorylation and reduction of LPS-induced NFκB nuclear translocation via prevention of IκBα degradation. Here, we provide proof-of-concept data highlighting Fpr2 as a potential target for control of microglial pro-inflammatory activity, suggesting that it may be a promising therapeutic target for the treatment of neuroinflammatory disease. Full article

Microglial cells have been demonstrated to be significant resident immune cells that maintain homeostasis under physiological conditions. However, prolonged or excessive microglial activation leads to disturbances in the resolution of inflammation (RoI). Formyl peptide receptor 2 (FPR2) is a crucial player in the RoI, interacting with various ligands to induce distinct conformational changes and, consequently, diverse biological effects. Due to the poor pharmacokinetic properties of endogenous FPR2 ligands, the aim of our study was to evaluate the pro-resolving effects of a new ureidopropanamide agonist, compound AMS21, in hippocampal organotypic cultures (OHCs) stimulated with lipopolysaccharide (LPS). Moreover, to assess whether AMS21 exerts its action via FPR2 specifically located on microglial cells, we conducted a set of experiments in OHCs depleted of microglial cells using clodronate. We demonstrated that the protective and anti-inflammatory activity of AMS21 manifested as decreased levels of lactate dehydrogenase (LDH), nitric oxide (NO), and proinflammatory cytokines IL-1β and IL-6 release evoked by LPS in OHCs. Moreover, in LPS-stimulated OHCs, AMS21 treatment downregulated NLRP3 inflammasome-related factors (CASP1, NLRP3, PYCARD) and this effect was mediated through FPR2 because it was blocked by the FPR2 antagonist WRW4 pre-treatment. Importantly this beneficial effect of AMS21 was only observed in the presence of microglial FPR2, and absent in OHCs depleted with microglial cells using clodronate. Our results strongly suggest that the compound AMS21 exerts, at nanomolar doses, protective and anti-inflammatory properties and an FPR2 receptor located specifically on microglial cells mediates the anti-inflammatory response of AMS21. Therefore, microglial FPR2 represents a promising target for the enhancement of RoI. Full article

Alcohol-associated liver disease (ALD) is the most common chronic liver disease and carries a significant healthcare burden. ALD has no long-term treatment options aside from abstinence, and the mechanisms that contribute to its pathogenesis are not fully understood. This study aimed to investigate the role of formyl peptide receptor 2 (FPR2), a receptor for immunomodulatory signals, in the pathogenesis of ALD. WT and Fpr2^−/− mice were exposed to chronic–binge ethanol administration and subsequently assessed for liver injury, inflammation, and markers of regeneration. The differentiation capacity of liver macrophages and the oxidative burst activity of neutrophils were also examined. Compared to WT, Fpr2^−/− mice developed more severe liver injury and inflammation and had compromised liver regeneration in response to ethanol administration. Fpr2^−/− mice had fewer hepatic monocyte-derived restorative macrophages, and neutrophils isolated from Fpr2^−/− mice had diminished oxidative burst capacity. Fpr2^−/− MoMF differentiation was restored when co-cultured with WT neutrophils. Loss of FPR2 led to exacerbated liver damage via multiple mechanisms, including abnormal immune responses, indicating the crucial role of FPR2 in ALD pathogenesis. Full article

In diabetic retinopathy (DR), Müller cell gliosis contributes to retinal degeneration and inflammation. In this context, we highlight annexin A1 (AnxA1), an anti-inflammatory protein able to regulate neurodegeneration and angiogenesis; however, its mechanisms of action were poorly explored in DR. This study evaluates the function of AnxA1 in streptozotocin (STZ)-induced DR in wild-type (WT) and knockout (AnxA1^-/-) mice after 12 weeks. In addition, in silico analysis was performed with GSE111465 (whole retinas from 6-week-old STZ-diabetic or control animals) and GSE160306 (human retinas with different stages of DR). Retinas from 6-week-old STZ-diabetic mice showed raised transcripts of AnxA1 and GFAP compared to the controls. After 12 weeks, RD was associated with increased levels of AnxA1, formyl peptide receptor 2 (Fpr2) in the WT retina, as well as cleaved caspase 3 and vascular endothelial growth factor (VEGF) compared to the control samples. The lack of AnxA1 caused increased glutamine synthetase expression (Müller cell marker) in the retinas from RD animals compared to the WT RD group. On the other hand, no alterations in the levels of caspase 3 and VEGF expression were showed in the AnxA1^-/- groups. Despite both genotypes presenting with gliosis in the peripheral retinas, as shown by glial fibrillary acid protein (GFAP) immunostaining, the AnxA1^-/- RD group exhibited decreased levels of GFAP compared to the RD WT group. In an in silico study with human retinas, the severity of DR is associated with higher levels of AnxA1 mRNA expression. Additionally, a positive correlation between AnxA1 and GFAP mRNA levels was detected. These results allow us to conclude that AnxA1 participates in the progression of RD and that this protein can regulate the expression of GFAP. Full article

Coronavirus disease 2019 (COVID-19), the current global pandemic is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Various pharmaceuticals are being developed to counter the spread of the virus. The strategy of repurposing known drugs and bioactive molecules is a rational approach. A previously described molecule, Ile-Arg-Trp (IRW), is a bioactive tripeptide that exhibits an ability to boost angiotensin converting enzyme-2 (ACE2) expression in animals and cells. Given the importance of SARS-CoV-2 S receptor binding domain (RBD)-ACE2 interaction in SARS-CoV-2 pathophysiology, we synthesized various IRW analogs intending to mitigate the RBD-ACE-2 interaction. Herein, we describe two analogs of IRW, A9 (Acetyl-Ile-Arg-Trp-Amide) and A14 (Formyl-Ile-Arg-Trp-Amide) which lowered the SARS-CoV-2 S RBD-ACE2 (at 50 µM) in vitro. The free energy of binding suggested that A9 and A14 interacted with the SARS-CoV-2 S RBD more favorably than ACE2. The calculated MMGBSA ΔG of spike binding for A9 was −57.22 kcal/mol, while that of A14 was −52.44 kcal/mol. A14 also inhibited furin enzymatic activity at various tested concentrations (25, 50, and 100 µM). We confirmed the effect of the two potent analogs using SARS-CoV-2 spike protein overexpressing cells. Both peptides lowered the protein expression of SARS-CoV-2 spike protein at the tested concentration (50 µM). Similarly, both peptides, A9 and A14 (50 µM), also inhibited pseudotyped lentiviral particles with SARS-CoV-2 Spike in ACE2 overexpressing cells. Further, the molecular dynamics (MD) calculations showed the interaction of A9 and A14 with multiple residues in spike S1 RBD. In conclusion, novel peptide analogs of ACE2 boosting IRW were prepared and confirmed through in vitro, cellular, and computational evaluations to be potential seed candidates for SARS-CoV-2 host cell binding inhibition. Full article

Formyl peptide receptor (FPR) 2 is known to play a critical role in regulating inflammation, including either the pro-inflammatory or pro-resolving effects. However, its role in neonatal hyperoxia-induced lung injury has not been delineated. In this study, we investigate whether mesenchymal stem cells (MSCs) attenuate hyperoxia-induced neonatal lung injury by regulating FPR2 activity. We observed a significant increase in FPR2 levels in alveolar macrophages (RAW264.7 cells) after H₂O₂-induced stress, which decreased after MSC treatment. In the H₂O₂-induction model, increased levels of inflammatory cytokines (IL-1α and TNF-α) were significantly reduced in RAW264.7 cells after treatment with WRW4, an inhibitor of FPR2, or MSCs. Viability of lung epithelial cells and endothelial cells was significantly improved when cultured in the conditioned media of RAW264.7 cells treated with WRW4 or MSCs, compared to when cultured in the conditioned media of control RAW265.7 cells exposed to H₂O₂. For the in vivo study, wild-type and FPR2 knockout (FPR2^−/−) C57/BL6 mouse pups were randomly exposed to 80% oxygen or room air from postnatal day (P) 1 to P14. At P5, 2 × 10⁵ MSCs were transplanted intratracheally. MSCs reduced the elevated FPR2 activity at P7 and improved the decreased FPR2 activity as well as the increased immuno-stained FPR2 activity in alveolar macrophages in hyperoxic lungs at P14. Both FPR2^−/− and MSCs similarly attenuated impaired alveolarization and angiogenesis, and increased apoptosis and inflammation of hyperoxic lungs without synergistic effects. Our findings suggest that the protective effects of MSCs in hyperoxic lung injury might be related to indirect modulation of FPR2 activity, at least of alveolar macrophages in neonatal mice. Full article