Search Results (85)

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

In physiological situations involving cell damage, molecules derived from mitochondria or bacteria are produced. These molecules are known as N-formyl peptides and are detected by formyl peptide receptors (FPRs), which stimulate immune cells to migrate to the specific site of injury or infection. Despite their initially beneficial effects on health, N-formyl peptides also contribute to the development or exacerbation of chronic non-communicable diseases. Therefore, understanding the metabolic pathways related to the involvement of N-formyl peptides and FPRs may increase our ability to regulate immune responses and precisely target FPRs with personalized strategies, offering a promising approach for the treatment of specific diseases. In this way, bioactive compounds in food may influence N-formyl peptides, interacting with the receptors either competitively or by inhibiting them, which affects the inflammatory response and oxidative reactions of cells. This review examines the pathways associated with forming N-formyl peptides, the activation of FPRs, and the roles of bioactive compounds in regulating N-formyl peptides. 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

Background: the treatment of squamous cell carcinomas of the oral cavity (OSCCs) is limited by the lack of reliable diagnostic/prognostic, and predictive markers, as well as by intrinsic tumor cell heterogeneity. 5-azacytidine (5-AZA) offers opportunities for cancer cell reprogramming to develop new target-specific treatments. The protein annexin A1 (ANXA1) is downregulated in head and neck squamous cell carcinoma (HNSCC), correlated with pathological differentiation grade. Objectives: this work aimed to further investigate the role of ANXA1 in OSCC progression based on 5-AZA activity. Methods: we used CAL27 and CAL33 cell lines, which differ in drug sensitivity and differentiation status. Results: CAL27 showed a higher expression of the stemness markers compared to CAL33 cells, but this positivity was lost after treatment with 5-AZA. This drug also decreased CAL27 cell motility, promoting a less aggressive phenotype. Moreover, 5-AZA increased ANXA1 expression only in CAL27. After siRNA-mediated downmodulation, we witnessed a significant rise in cell motility and the inversion of E-/N-cadherin expression, which was reverted again by 5-AZA. To investigate the role of exogenous ANXA1 derived from the tumor microenvironment, we treated CAL27 with Ac2-26, an ANXA1 mimetic peptide. Interestingly, we found that this peptide alone showed impacts similar to 5-AZA in reversing the aggressive phenotype. All these effects were not evidenced in CAL33 cells. Finally, to prove the loop of the exogenous protein, we detected increased expression of its receptors, formyl peptide receptors (FPRs), and their activation, leading to oncosuppressor effects. Conclusions: we propose that ANXA1 mediates the effects of 5-AZA only in poorly differentiated stemlike CAL27 cell lines. This suggests the relevance of ANXA1 as a diagnostic/prognostic biomarker in OSCCs, paving the way for personalized therapies to overcome treatment difficulties. 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

Background: The brain is protected from invading pathogens by the blood−brain barrier (BBB) and the innate immune system. Pattern recognition receptors play a crucial role in detecting bacteria and initiating the innate immune response. Among these are G-protein-coupled formyl peptide receptors (FPR), which are expressed by immune cells in the central nervous system. In this study, we investigated the influence of the FPR ligand Ac2-26 on the integrity of the BBB during pneumococcal meningitis. Methods: Wild-type (WT) and Fpr1- and Fpr2-deficient mice were intrathecally infected with Streptococcus pneumoniae. Subsequently, different groups of mice were treated with intraperitoneal injections of Ac2-26. The integrity of the BBB was analyzed using various markers through immunohistochemistry and immunofluorescence. Results: The results showed reduced BBB integrity during the course of bacterial meningitis. Treatment with Ac2-26 in WT mice significantly prolonged the maintenance of BBB integrity. However, this effect was not observed in Fpr2-deficient mice. Conclusions: This study extends previous findings on the anti-inflammatory properties of Ac2-26 by demonstrating that Ac2-26 positively affects BBB integrity via FPR2 during pneumococcal meningitis. These findings suggest that further investigation of Ac2-26 and other FPR modulators as potential therapies for Streptococcus pneumoniae-induced meningitis is warranted. 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

Systemic Sclerosis (SSc) is a heterogeneous autoimmune disease characterized by widespread vasculopathy, the presence of autoantibodies and the progressive fibrosis of skin and visceral organs. There are still many questions about its pathogenesis, particularly related to the complex regulation of the fibrotic process, and to the factors that trigger its onset. Our recent studies supported a key role of N-formyl peptide receptors (FPRs) and their crosstalk with uPAR in the fibrotic phase of the disease. Here, we found that dermal fibroblasts acquire a proliferative phenotype after the activation of FPRs and their interaction with uPAR, leading to both Rac1 and ERK activation, c-Myc phosphorylation and Cyclin D1 upregulation which drive cell cycle progression. The comparison between normal and SSc fibroblasts reveals that SSc fibroblasts exhibit a higher proliferative rate than healthy control, suggesting that an altered fibroblast proliferation could contribute to the initiation and progression of the fibrotic process. Finally, a synthetic compound targeting the FPRs/uPAR interaction significantly inhibits SSc fibroblast proliferation, paving the way for the development of new targeted therapies in fibrotic diseases. 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

The soluble urokinase plasminogen activator receptor (suPAR) has been implicated in a wide range of pathological conditions including primary nephrotic syndromes and acute kidney injuries. suPAR can trigger transduction cascades in podocytes by outside-in activation of αVβ3-integrin, but there is evidence that the functional cell surface response element is actually a complex of different types of receptors, which may also include the receptor for advanced glycation end-products (RAGE) and formyl peptide receptors (FPRs). Here we observed that ROS accumulation and Src activation could be evoked by continuous 24 h exposure to either suPAR or the FPR agonist fMLF. Responses to suPAR and fMLF were completely blocked by either the FPR antagonist WRW4 or by the αV-integrin inhibitor cilengitide. Moreover, endogenous podocyte mouse Fpr1 co-immunoprecipitates with β3-integrin, suggesting that these receptors occur as a complex on the cell surface. suPAR- and fMLF-evoked activation of Src and ROS differed in time course. Thus, robust pertussis toxin (PTX)-sensitive responses were evoked by 60 min exposures to fMLF but not to suPAR. By contrast, responses to 24 h exposures to either suPAR or fMLF were PTX-resistant and were instead abolished by knockdown of β-arrestin-1 (BAR1). FPRs, integrins, and RAGE (along with various Toll-like receptors) can all function as pattern-recognition receptors that respond to “danger signals” associated with infections and tissue injury. The fact that podocytes express such a wide array of pattern-recognition receptors suggests that the glomerular filter is designed to change its function under certain conditions, possibly to facilitate clearance of toxic macromolecules. 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

Rheumatoid arthritis is an autoimmune disorder that causes chronic joint pain, swelling, and movement impairment, resulting from prolonged inflammation-induced cartilage and bone degradation. The pathogenesis of RA, which is still unclear, makes diagnosis and treatment difficult and calls for new therapeutic strategies to cure the disease. Recent research has identified FPRs as a promising druggable target, with AMC3, a novel agonist, showing preclinical efficacy in vitro and in vivo. In vitro, AMC3 (1–30 µM) exhibited significant antioxidant effects in IL-1β (10 ng/mL)-treated chondrocytes for 24 h. AMC3 displayed a protective effect by downregulating the mRNA expression of several pro-inflammatory and pro-algic genes (iNOS, COX-2, and VEGF-A), while upregulating genes essential for structural integrity (MMP-13, ADAMTS-4, and COLIAI). In vivo, AMC3 (10 mg kg⁻¹) prevented hypersensitivity and restored postural balance in CFA-injected rats after 14 days. AMC3 attenuated joint alterations, reduced joint inflammatory infiltrate, pannus formation, and cartilage erosion. Chronic AMC3 administration reduced transcriptional changes of genes causing excitotoxicity and pain (EAATs and CCL2) and prevented morphological changes in astrocytes, including cell body hypertrophy, processes length, and thickness, caused by CFA in the spinal cord. This study demonstrates the usefulness of AMC3 and establishes the groundwork for further research. Full article