Search Results (44)

Several of the integrin family of cell adhesion receptors have been popular targets for the development of anticancer agents, but with little clinical success to date. Cancer cells usually express multiple redundant integrins; one hypothesis for the lack of efficacy of current antagonists is their high selectivity for a single integrin. To address this, we developed a functional dual-β3-expressing cell model to investigate the effects of combined αIIbβ3/αvβ3 antagonism. We established that treating K562 chronic myeloid leukemia cells with 0.04 μM phorbol 12-myristate 13-acetate (PMA) for 40 h significantly upregulates functional αIIbβ3 and αvβ3 integrins. This optimized method provides a reliable platform for adhesion and detachment assays, enabling the characterization of dual integrin targeting strategies. Using this model, we demonstrate that combining αIIbβ3 and αvβ3 antagonists (GR144053 and cRGDfV) synergistically enhances inhibition of cell adhesion and promotes cell detachment compared to single-agent treatments. Our findings establish a reproducible approach for studying dual β3 integrin targeting, which can be used to investigate potential strategies for overcoming integrin redundancy in cancer therapeutics. Full article

The identification of exogenous ligands from natural products is an alternative strategy to explore the unrevealed physiological functions of orphan G-protein-coupled receptors (GPCRs). In this study, we have successfully identified and pharmacologically characterized licoisoflavone A (LIA) as a novel selective antagonist of BRS-3, an orphan GPCR. Functional studies showed that pretreatment with LIA ameliorated hydrogen peroxide (H₂O₂)-induced cardiomyocyte injury. Furthermore, LIA pretreatment significantly restored the activities of malondialdehyde (MDA), superoxide dismutase (SOD), and catalase (CAT), as well as lactate dehydrogenase (LDH) levels, in H9c2 cells following H₂O₂ exposure. The protective effect of LIA was also evident in primary cardiomyocytes from rats and mice against H₂O₂-induced cell injury but was absent in primary cardiomyocytes derived from bombesin receptor subtype-3 knockout (Brs3^−/y) mice, strongly confirming the mechanism of LIA’s action through BRS-3 antagonism. Proteomics studies further revealed that LIA exerted its protective effects via activating the integrin/ILK/AKT and ERK/MAPK signaling pathways. Complementary findings from Bantag-1, a well-recognized antagonist of BRS-3, in human embryonic kidney 293 mBRS-3 (HEK293-mBRS-3) stable cells and B16 cell lines, which demonstrated resistance to H₂O₂-induced damage, further supported the pivotal role of BRS-3 in oxidative stress-induced cell injury. Our study contributes to expanding our understanding of the potential pharmacological functions of BRS-3, unveiling previously unknown pharmacological functionality of this orphan receptor. Full article

The family of the β₂-integrin receptors is critically involved in host defense and homeostasis, by mediating immune cell adhesion, migration, and phagocytosis. Due to their key roles in immune surveillance and inflammation, their modulation has been recognized as an attractive drug target. However, the development of therapeutics has been limited, partly due to the high promiscuity of endogenous ligands, their functional responses, and gaps in our understanding of their disease-related molecular mechanisms. The delineation of the molecular role of β₂ integrins and their ligands has been hampered by a shortage of validated assay systems. To facilitate molecular and functional studies on the β₂-integrin family, and to enable screening of modulators, this study provides a uniform and validated assay platform. For this purpose, the major ligand-binding domains (αI) of all four β₂ integrins were recombinantly expressed in both low- and high-affinity states. By optimizing the expression parameters and selecting appropriate purification tags, all αI-domain variants could be produced with high yield and purity. Direct binding studies using surface plasmon resonance (SPR) confirmed the expected activity and selectivity profiles of the recombinant αI domains towards their reported ligands, validating our approach. In addition, the SPR studies provided additional insights into ligand binding, especially for the scarcely described family member CD11d. Alongside characterizing endogenous ligands, the platform can be employed to test pharmacologically active compounds, such as the reported β₂-integrin antagonist simvastatin. In addition, we established a bead-based adhesion assay using the recombinant αI domains, and a cell-based adhesion assay underlining most findings generated with the isolated αI domains. Interestingly, the binding of ligands to the recombinant α_DI is not dependent on divalent cation, in contrast to the full integrin CD11d/CD18, suggesting a binding mode distinct of the metal ion-dependent adhesion site (MIDAS). The setup highlights the applicability of recombinant αI domains for first screenings and direct or competitive interaction studies, while the full integrin is needed to validate those findings. Full article

Introduction: Crohn’s disease is a chronic inflammatory bowel disease characterized by abdominal pain, diarrhea, and other symptoms. It can lead to significant complications and impact patients’ quality of life. Therefore, effective management strategies are essential for improving outcomes. Methods: To assess the efficacy of the treatments for Crohn’s disease, this umbrella review systematically addresses systematic reviews and meta-analyses on Crohn’s disease management published between 2013 and 2023. The quality of the included studies was assessed using the National Institutes of Health’s quality assessment tool. Results: Sixteen studies were included, evaluating various interventions for the induction and maintenance of remission. These included biologic agents (anti-TNF agents, anti-IL-12/23p40 antibodies, and integrin receptor antagonists), antimetabolites, and corticosteroids. Conclusions: The findings suggest that biologic agents may be promising options for both the induction and maintenance of remission in Crohn’s disease. Antimetabolites and corticosteroids may be effective in certain cases, but their efficacy and safety profiles require further investigation. The included studies varied in quality and sample size. More research is needed to confirm the findings and establish optimal treatment strategies. Moreover, while biologic agents show promise, the optimal management of Crohn’s disease requires further research. A personalized approach considering patient factors and disease characteristics is crucial for optimizing outcomes. Full article

Heart failure is a complex syndrome characterized by cardiac hypertrophy, fibrosis, and diastolic/systolic dysfunction. These changes share many pathological features with significant inflammatory responses in the myocardium. Among the various regulatory systems that impact on these heterogeneous pathological processes, angiotensin II (Ang II)-activated macrophages play a pivotal role in the induction of subcellular defects and cardiac adverse remodeling during the progression of heart failure. Ang II stimulates macrophages via its AT1 receptor to release oxygen-free radicals, cytokines, chemokines, and other inflammatory mediators in the myocardium, and upregulates the expression of integrin adhesion molecules on both monocytes and endothelial cells, leading to monocyte-endothelial cell-cell interactions. The transendothelial migration of monocyte-derived macrophages exerts significant biological effects on the proliferation of fibroblasts, deposition of extracellular matrix proteins, induction of perivascular/interstitial fibrosis, and development of hypertension, cardiac hypertrophy and heart failure. Inhibition of macrophage activation using Ang II AT1 receptor antagonist or depletion of macrophages from the peripheral circulation has shown significant inhibitory effects on Ang II-induced vascular and myocardial injury. The purpose of this review is to discuss the current understanding in Ang II-induced maladaptive cardiac remodeling and dysfunction, particularly focusing on molecular signaling pathways involved in macrophages-mediated hypertension, cardiac hypertrophy, fibrosis, and failure. In addition, the challenges remained in translating these findings to the treatment of heart failure patients are also addressed. Full article

Background: Platelets have been shown to promote ovarian cancer; however, the mechanism is poorly understood. Previously, we demonstrated that platelets reduce the size and increase the density of multi-cellular ovarian cancer spheroids in cell cultures. The objectives of this study were to determine if platelet inhibitors could counteract these effects, and to explore the mechanisms involved. Methods: FDA-approved platelet inhibitors were screened for their abilities to alter platelet effects on ovarian cancer spheroids. Mass spectrometry was used to identify proteins significantly altered in cancer cells upon exposure to platelets. The effects of platelets and/or liver x receptor agonists or antagonists on LXR activity were measured using ES-2 ovarian cancer cells transduced with an LXR-reporter vector. Results: Eptifibatide, a GPIIB-IIIA integrin inhibitor, and dipyridamole, an adenosine reuptake inhibitor, reduced and enhanced platelet effects on ovarian cancer spheroids, respectively. Proteomic studies identified the LXR/RXR and integrin pathways as mediators of platelet effects on ovarian cancer, and downstream effectors of eptifibatide. Conclusions: Integrin pathways and their downstream LXR/RXR effectors are implicated in how platelets alter ovarian cancer spheroid morphology. These results support studying eptifibatide and LXR/RXR agonists as candidate drugs for repurposing as therapeutic strategies to counteract platelet promotion of ovarian cancer. Full article

C-C Chemokine Receptor 7 (CCR7) mediates T-cell acute lymphoblastic leukemia (T-ALL) invasion of the central nervous system (CNS) mediated by chemotactic migration to C-C chemokine ligand 19 (CCL19). To determine if a CCL19 antagonist, CCL19_8-83, could inhibit CCR7-induced chemotaxis and signaling via CCL19 but not CCL21, we used transwell migration and Ca²⁺ mobilization signaling assays. We found that in response to CCL19, human T-ALL cells employ β2 integrins to invade human brain microvascular endothelial cell monolayers. In vivo, using an inducible mouse model of T-ALL, we found that we were able to increase the survival of the mice treated with CCL19_8-83 when compared to non-treated controls. Overall, our results describe a targetable cell surface receptor, CCR7, which can be inhibited to prevent β2-integrin-mediated T-ALL invasion of the CNS and potentially provides a platform for the pharmacological inhibition of T-ALL cell entry into the CNS. Full article

Introduction: The management of Crohn’s disease (CD) in the Middle East, like in other parts of the world, is rapidly evolving with the introduction of novel advanced medical and biological therapies. In the United Arab Emirates (UAE), several biological therapies are used to achieve remission in severe and resistant cases of CD. We carried out a literature search to analyze the effectiveness and safety of biologic treatments currently licensed in the UAE. Methods: We searched the PubMed, Embase and Cochrane library databases from inception to January 2020 to identify relevant studies. Search terms were generated using established treatment guidelines for CD. We also manually searched the bibliographies of relevant literature to obtain additional papers. Results: Biologic and small molecule agents for CD include four core drug classes: anti-tumor necrosis factor-α agents (TNF-α), integrin receptor antagonists, Janus kinase (JAK) inhibitors and IL-12/IL-23 antagonists. All drug classes showed good efficacy and safety in managing patients with CD. Some drug classes had distinguishable side effect profiles. This included an increased lymphoma and tuberculous risk for TNF-α and integrin receptor antagonists. Many trials supported the effectiveness of these licensed drugs. Biologic agent intolerance was common; one-third of patients receiving TNF-α treatment will develop intolerance to that specific drug. Conclusions: Advanced medical therapies licensed in the UAE have proven to be safe and efficacious. Additional research is required to evaluate the safety and efficacy of newer biologics and biosimilars. Full article

Vedolizumab (VDZ) is used for treating inflammatory bowel disease (IBD) patients. A study investigating colonic epithelial barrier function ex vivo following VDZ is lacking. This work aims to evaluate ex vivo the colonic epithelial barrier function in IBD patients at baseline and during VDZ treatment, and to investigate the relationships between barrier function and clinical parameters. Colonic specimens were obtained from 23 IBD patients before, and at 24 and 52 weeks after VDZ treatment, and from 26 healthy volunteers (HV). Transepithelial electrical resistance (TEER, permeability to ions) and paracellular permeability were measured in Ussing chambers. IBD patients showed increased epithelial permeability to ions (TEER, 13.80 ± 1.04 Ω × cm² vs. HV 20.70 ± 1.52 Ω × cm², p < 0.001) without changes in paracellular permeability of a 4 kDa probe. VDZ increased TEER (18.09 ± 1.44 Ω × cm², p < 0.001) after 52 weeks. A clinical response was observed in 58% and 25% of patients at week 24, and in 62% and 50% at week 52, in ulcerative colitis and Crohn’s disease, respectively. Clinical and endoscopic scores were strongly associated with TEER. TEER < 14.65 Ω × cm² predicted response to VDZ (OR 11; CI 2–59). VDZ reduces the increased permeability to ions observed in the colonic epithelium of IBD patients before treatment, in parallel to a clinical, histological (inflammatory infiltrate), and endoscopic improvement. A low TEER predicts clinical response to VDZ therapy. Full article

To develop peptide drugs targeting integrin receptors, synthetic peptide ligands endowed with well-defined selective binding motifs are necessary. The snake venom KTS-containing disintegrins, which selectively block collagen α1β1 integrin, were used as lead compounds for the synthesis and structure–activity relationship of a series of linear peptides containing the KTS-pharmacophore and alternating natural amino acids and 3-aminobenzoic acid (MABA). To ensure a better stiffness and metabolic stability, one, two and three MABA residues, were introduced around the KTS pharmacophore motif. Molecular dynamics simulations determined that the solution conformation of MABA peptide 4 is more compact, underwent larger conformational changes until convergence, and spent most of the time in a single cluster. The peptides’ binding affinity has been characterized by an enzyme linked immunosorbent assay in which the most potent peptide 4 inhibited with IC₅₀ of 324 ± 8 µM and 550 ± 45 µM the binding of GST-α1-A domain to collagen IV fragment CB3, and the cell adhesion to collagen IV using α1-overexpressor cells, respectively. Docking studies and MM-GBSA calculations confirmed that peptide 4 binds a smaller region of the integrin near the collagen-binding site and penetrated deeper into the binding site near Trp1. Peptide 4 inhibited tube formation by endothelial cell migration in the Matrigel angiogenesis in vitro assay. Peptide 4 was acutely tolerated by mice, showed stability in human serum, decreased tumor volume and angiogenesis, and significantly increased the survival of mice injected with B16 melanoma cells. These findings propose that MABA-peptide 4 can further serve as an α1β1-integrin antagonist lead compound for further drug optimization in angiogenesis and cancer therapy. Full article

Integrins are heterodimeric cell-surface receptors that regulate cell–cell adhesion and cellular functions through bidirectional signaling. On the other hand, anomalous trafficking of integrins is also implicated in severe pathologies as cancer, thrombosis, inflammation, allergies, and multiple sclerosis. For this reason, they are attractive candidates as drug targets. However, despite promising preclinical data, several anti-integrin drugs failed in late-stage clinical trials for chronic indications, with paradoxical side effects. One possible reason is that, at low concentration, ligands proposed as antagonists may also act as partial agonists. Hence, the comprehension of the specific structural features for ligands’ agonism or antagonism is currently of the utmost interest. For α4β1 integrin, the situation is particularly obscure because neither the crystallographic nor the cryo-EM structures are known. In addition, very few potent and selective agonists are available for investigating the mechanism at the basis of the receptor activation. In this account, we discuss the physiological role of α4β1 integrin and the related pathologies, and review the few agonists. Finally, we speculate on plausible models to explain agonism vs. antagonism by comparison with RGD-binding integrins and by analysis of computational simulations performed with homology or hybrid receptor structures. Full article

Integrin receptors are heterodimeric surface receptors that play multiple roles regarding cell–cell communication, signaling, and migration. The four members of the β₂ integrin subfamily are composed of an alternative α (CD11a–d) subunit, which determines the specific receptor properties, and a constant β (CD18) subunit. This review aims to present insight into the multiple immunological roles of integrin receptors, with a focus on β₂ integrins that are specifically expressed by leukocytes. The pathophysiological role of β₂ integrins is confirmed by the drastic phenotype of patients suffering from leukocyte adhesion deficiencies, most often resulting in severe recurrent infections and, at the same time, a predisposition for autoimmune diseases. So far, studies on the role of β₂ integrins in vivo employed mice with a constitutive knockout of all β₂ integrins or either family member, respectively, which complicated the differentiation between the direct and indirect effects of β₂ integrin deficiency for distinct cell types. The recent generation and characterization of transgenic mice with a cell-type-specific knockdown of β₂ integrins by our group has enabled the dissection of cell-specific roles of β₂ integrins. Further, integrin receptors have been recognized as target receptors for the treatment of inflammatory diseases as well as tumor therapy. However, whereas both agonistic and antagonistic agents yielded beneficial effects in animal models, the success of clinical trials was limited in most cases and was associated with unwanted side effects. This unfavorable outcome is most probably related to the systemic effects of the used compounds on all leukocytes, thereby emphasizing the need to develop formulations that target distinct types of leukocytes to modulate β₂ integrin activity for therapeutic applications. 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

Integrins were originally identified as receptors for extracellular matrix (ECM) and cell-surface molecules (e.g., VCAM-1 and ICAM-1). Later, we discovered that many soluble growth factors/cytokines bind to integrins and play a critical role in growth factor/cytokine signaling (growth factor–integrin crosstalk). We performed a virtual screening of protein data bank (PDB) using docking simulations with the integrin headpiece as a target. We showed that several growth factors (e.g., FGF1 and IGF1) induce a integrin-growth factor-cognate receptor ternary complex on the surface. Growth factor/cytokine mutants defective in integrin binding were defective in signaling functions and act as antagonists of growth factor signaling. Unexpectedly, several growth factor/cytokines activated integrins by binding to the allosteric site (site 2) in the integrin headpiece, which is distinct from the classical ligand (RGD)-binding site (site 1). Since 25-hydroxycholesterol, a major inflammatory mediator, binds to site 2, activates integrins, and induces inflammatory signaling (e.g., IL-6 and TNFα secretion), it has been proposed that site 2 is involved in inflammatory signaling. We showed that several inflammatory factors (CX3CL1, CXCL12, CCL5, sPLA2-IIA, and P-selectin) bind to site 2 and activate integrins. We propose that site 2 is involved in the pro-inflammatory action of these proteins and a potential therapeutic target. It has been well-established that platelet integrin αIIbβ3 is activated by signals from the inside of platelets induced by platelet agonists (inside-out signaling). In addition to the canonical inside-out signaling, we showed that αIIbβ3 can be allosterically activated by inflammatory cytokines/chemokines that are stored in platelet granules (e.g., CCL5, CXCL12) in the absence of inside-out signaling (e.g., soluble integrins in cell-free conditions). Thus, the allosteric activation may be involved in αIIbβ3 activation, platelet aggregation, and thrombosis. Inhibitory chemokine PF4 (CXCL4) binds to site 2 but did not activate integrins, Unexpectedly, we found that PF4/anti-PF4 complex was able to activate integrins, indicating that the anti-PF4 antibody changed the phenotype of PF4 from inhibitory to inflammatory. Since autoantibodies to PF4 are detected in vaccine-induced thrombocytopenic thrombosis (VIPP) and autoimmune diseases (e.g., SLE, and rheumatoid arthritis), we propose that this phenomenon is related to the pathogenesis of these diseases. P-selectin is known to bind exclusively to glycans (e.g., sLex) and involved in cell–cell interaction by binding to PSGL-1 (CD62P glycoprotein ligand-1). Unexpectedly, through docking simulation, we discovered that the P-selectin C-type lectin domain functions as an integrin ligand. It is interesting that no one has studied whether P-selectin binds to integrins in the last few decades. The integrin-binding site and glycan-binding site were close but distinct. Also, P-selectin lectin domain bound to site 2 and allosterically activated integrins. Full article

IBD consists of two diseases—CD and UC—that affect the digestive tract, with a greater affinity for the large bowel. In this case report, we focus on one of its most common complications. CDI is a pathology that is mostly secondary to UC. Another cause of this bacterial infection is established after the use of antibiotics, most commonly at the hospital level. Around 20 percent of CDI persists because of a chronic dysbiosis of the microbiota and low levels of antibodies against CD toxins. In this case report, we demonstrated mdCDI in a young woman after treatment with multiple drug therapies as well as with semi-invasive procedures as follows: antibiotics (vancomycin, fidaxomicin), anti-inflammatory agents (mesalamine, sulfasalazine), corticosteroids (budesonide, prednisone), integrin receptor antagonists (vedolizumab), several semi-invasive procedures such as fecal transplant microbiota (FMT), aminosalicylates (5-ASA), treatment with tumor necrosis factor (TNF) blockers (adalimumab, golimumab), and immunomodulators (upadcitinib, tofacitinib). This leads us to establish how rCDI and its resistance to different treatments make this a challenge for the health system, both for hospitals and for outpatients, as well as how time-consuming each treatment is from the first intake of the drug until its total efficacy or until patients reach a dose-response and time-response to the disease. Accordingly, this case report and other similar cases reflect the need for randomized control trials or meta-analyses to establish therapeutic guidelines for cases of mdCDI in the near future. Full article