Quercetin reduces neutrophil recruitment induced by CXCL8, LTB4, and fMLP: inhibition of actin polymerization

Oral pectin/oligochitosan microspheres for colon-specific controlled release of quercetin to treat inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic, life quality-reducing disease with no cures available yet. To develop an effective medication suitable for long-term use is an urgent but unmet need. Quercetin (QT) is a natural dietary flavonoid with good safety and multifaceted pharmacological activities against inflammation. However, orally administrated quercetin yields unproductive outcomes for IBD treatment because of its poor solubility and extensive metabolism in the gastrointestinal tract. In this work, a colon-targeted QT delivery system (termed COS-CaP-QT) was developed, of which the pectin (PEC)/Ca²⁺ microspheres were prepared and then crosslinked by oligochitosan (COS). The drug release profile of COS-CaP-QT was pH-dependent and colon microenvironment-responsive, and COS-CaP-QT showed preferential distribution in the colon. The mechanism study showed that QT triggered the Notch pathway to regulate the proliferation of T helper 2 (Th2) cells and group 3 innate lymphoid cells (ILC3s) and the inflammatory microenvironment was remodeled. The in vivo therapeutic results revealed that COS-CaP-QT could relieve the colitis symptoms and maintain the colon length and intestinal barrier integrity.

Anti-Arthritis Effect of Ethanol Extract of Sacha Inchi (Plukenetia volubilis L.) Leaves Against Complete Freund's Adjuvant-Induced Arthritis Model in Mice

Sacha inchi (Plukenetia volubilis L.) is a well-known oleaginous plant used as food source and traditional medicine by indigenous people for a long time. This study was conducted to evaluate anti-arthritis effect of ethanol extract of Sacha inchi leaves and provide scientific evidence to develop the new anti-arthritis remedy from Sacha inchi. Rheumatoid arthritis model was established by injection of complete Freund's adjuvant into right hind footpads of mice and three doses of ethanol extract of Sacha inchi leaves (100, 200 and 300 mg/kg body weight) were used for treatment. The severity of arthritis was evaluated by measuring the ankle diameter and arthritic score, hematological and biochemical parameters (erythrocytes, leukocytes, lymphocytes, monocytes, granulocytes counts, erythrocyte sedimentation rate, C-reactive protein and rheumatoid factor). The pro-and anti-inflammatory cytokines (TNF-α, INF-γ, IL-1β, IL-6, and IL-10) and the histology change of joint were also examined. All three doses of extracts significantly alleviated ankle diameter and arthritic score. Furthermore, the extracts could ameliorate the alternation of inflammatory cytokines as well histological features of CFA-induced mice. The efficacy of extract dose of 300 mg/kg body weight is comparable with reference drug (Mobic, 0.2 mg/kg body weight). This study indicates Sacha inchi leaf extract as the promising remedy for treatment of arthritis.

Lafoensia pacari alleviates intestinal damage by modulating cyclooxygenase-2: In silico and in vivo evaluation in a colitis model

BACKGROUND

Inflammatory bowel diseases (IBD) are a worldwide health problem and mainly affect young people, consequently affecting the workforce. Available treatments are often associated with side effects, and new therapeutic options are needed. For centuries, plants have represented important substrates in the field of drug development. Lafoensia pacari (L. pacari) is a plant whose pharmaceutical potential has been described, and may have biological activity relevant to the treatment of IBD symptoms.

AIM

To investigate the activity of keto-alcoholic extracts of L. pacari with respect to ameliorating the inflammatory and nociceptive symptoms of acute experimental colitis in mice.

METHODS

Keto-alcoholic extracts of L. pacari leaves and bark were administered to male and female Swiss mice weighing 25 g to 30 g (n = 8 male mice and n = 8 female mice). The effect of these extracts was observed in an acetic acid-induced acute experimental model of colitis with regard to antinociception/analgesia and inflammatory tissue damage. Recorded macroscopic indices included the Wallace score and the colon weight obtained using a precision scale. Mechanical hyperalgesia was determined using an electronic analgesimeter. Behavior related to overt pain was determined by quantifying the number of writhing instances within 20 min of administration of acetic acid. Molecular docking was performed using human and murine cyclooxygenase-2 (COX-2) with 3 flavonoids (ellagic acid, kaempferol, and quercetin) on the AutoDock Vina software. Analysis of variance followed by Tukey’s posttest was used with P < 0.05 indicating significance.

RESULTS

In this murine model of colitis, administration of extracts from L. pacari ameliorated acetic acid-induced writhing and colitis-associated inflammatory pain. These improvements may be attributable to the reduction in edema, inflammation (e.g., ulcers, hyperemia, and bowel wall damage), and the intensity of abdominal hyperalgesia. The keto-alcoholic extracts of L. pacari leaves and bark administered at a dose of either 100 mg/kg or 300 mg/kg significantly reduced the number of writhing events when compared to the negative control (P < 0.05). Additionally, extracts of L. pacari bark also performed better than Dipyrone. Leaf extracts administered at 10 mg/kg, 30 mg/kg, and 100 mg/kg and bark extracts administered at 30 mg/kg significantly reduced or prevented the development of edema in the colon of treated mice, while mesalazine did not. Moreover, using molecular docking, we observed that the flavonoids present in L. pacari extracts bind to COX-2, an event not unique to ellagic acid.

CONCLUSION

The results of this study demonstrate a potential novel application of L. pacari extracts for the reduction of inflammation and promotion of antinociception/analgesia as demonstrated by our findings in a murine model of colitis. These findings were also corroborated by in silico analyses, and suggest that L. pacari extracts may be a promising therapeutic agent in the treatment of IBD.

Quercetin: A Functional Food-Flavonoid Incredibly Attenuates Emerging and Re-Emerging Viral Infections through Immunomodulatory Actions

Many of the medicinally active molecules in the flavonoid class of phytochemicals are being researched for their potential antiviral activity against various DNA and RNA viruses. Quercetin is a flavonoid that can be found in a variety of foods, including fruits and vegetables. It has been reported to be effective against a variety of viruses. This review, therefore, deciphered the mechanistic of how Quercetin works against some of the deadliest viruses, such as influenza A, Hepatitis C, Dengue type 2 and Ebola virus, which cause frequent outbreaks worldwide and result in significant morbidity and mortality in humans through epidemics or pandemics. All those have an alarming impact on both human health and the global and national economies. The review extended computing the Quercetin-contained natural recourse and its modes of action in different experimental approaches leading to antiviral actions. The gap in effective treatment emphasizes the necessity of a search for new effective antiviral compounds. Quercetin shows potential antiviral activity and inhibits it by targeting viral infections at multiple stages. The suppression of viral neuraminidase, proteases and DNA/RNA polymerases and the alteration of many viral proteins as well as their immunomodulation are the main molecular mechanisms of Quercetin's antiviral activities. Nonetheless, the huge potential of Quercetin and its extensive use is inadequately approached as a therapeutic for emerging and re-emerging viral infections. Therefore, this review enumerated the food-functioned Quercetin source, the modes of action of Quercetin for antiviral effects and made insights on the mechanism-based antiviral action of Quercetin.

Anti-Inflammatory Activity and Chemical Analysis of Different Fractions from Solidago chilensis Inflorescence

Solidago chilensis Meyen (Compositae) is a species native to South America (Brazil) popularly known as arnica. In Brazilian popular medicine, inflorescences and rhizomes of this plant have been used since the end of the 19th century to replace the exogenous and hepatotoxic Arnica montana L. in the treatment of edema and inflammatory pathologies. Although the anti-inflammatory activity of S. chilensis is evidenced in the literature, there is a lack of studies with enriched fractions or compounds isolated from it. The objective of the current study was to characterize phytochemically and to evaluate the pharmacological action in vivo and in vitro of the crude extract and the different fractions (hexane, dichloromethane, acetal, butanolic, and aqueous) isolated from the inflorescence of S. chilensis. The inflorescence crude extract (ScIE) and fractions were administered by intraperitoneal route to mice at different doses. In an LPS-induced pleurisy model, inhibition of leukocyte influx was observed for the ScIE and all fractions tested, as compared to controls. Dichloromethane (ScDicF), butanolic (ScButF), and aqueous (ScAquF) were selected for further analysis as they showed the best inhibitory effects in leukocyte migration and inflammatory cytokine and chemokine production: TNF-α, CXCL1/KC, CXCL2/MIP-2, and CCL11/eotaxin-1. In LPS-stimulated J774A.1 cell line, ScIE and the ScDicF exhibited an inhibitory effect on nitric oxide (NO) production and downmodulated the COX-2 expression; ScAquF failed to modulate NO production and COX-2 expression. In phytochemical analysis, HPLC-UV-DAD chromatograms of ScDicF and ScAquF showed the main peaks with UV spectrum characteristics of flavonoids; chlorogenic acid and isoquercetin were the most present phytochemicals identified in the ScAquF, and a high number of n-alkanes was found in ScHexF. Our study was the first to address biological effects and correlate them to phytochemically characterized fractions from inflorescences of S. chilensis.

Effect of quercetin on formation of porcine neutrophil extracellular trap

Neutrophil extracellular trap (NET) formation is an immune response to the invasion of external microorganisms. Quercetin, a member of the flavonoid family found in fruits and vegetables, has been examined in multiple biological contexts. The objective of this study was to examine the effect of quercetin on porcine NET formation. We measured NET formation by peripheral blood polymorphonuclear cells (PMNs) using propidium iodide (PI) dye. The amount of tumor necrosis factor (TNF)-α in culture supernatants was quantified by ELISA, and TNF-α mRNA expression was measured by RT-PCR. Direct treatment of PMNs with quercetin did not affect NET formation; however, NET formation was inhibited by exposure to culture supernatant from peripheral blood mononuclear cells (PBMCs) treated with quercetin. By contrast, culture supernatant from PBMCs treated with lipopolysaccharide (LPS) induced high levels of NET formation of PMNs, and this effect was reduced by co-treatment with LPS and quercetin. In addition, treatment of PMNs with recombinant porcine (rp) TNF-α induced high levels of NET formation. PBMCs treated with LPS increased higher levels of TNF-α mRNA and protein, but this effect was weakened when they were co-treated with quercetin. These findings indicated that quercetin inhibits NET formation of PMNs by suppressing production of TNF-α from LPS-stimulated PBMCs. These results suggest that quercetin exerts an anti-inflammatory effect, mediated by down-regulation of TNF-α production from LPS-stimulated PBMCs, which inhibits NET formation in PMNs.

Natural Polyphenols as Immunomodulators to Rescue Immune Response Homeostasis: Quercetin as a Research Model against Severe COVID-19

The COVID-19 pandemic is caused by SARS-CoV-2 and is leading to the worst health crisis of this century. It emerged in China during late 2019 and rapidly spread all over the world, producing a broad spectrum of clinical disease severity, ranging from asymptomatic infection to death (4.3 million victims so far). Consequently, the scientific research is devoted to investigating the mechanisms of COVID-19 pathogenesis to both identify specific therapeutic drugs and develop vaccines. Although immunological mechanisms driving COVID-19 pathogenesis are still largely unknown, new understanding has emerged about the innate and adaptive immune responses elicited in SARS-CoV-2 infection, which are mainly focused on the dysregulated inflammatory response in severe COVID-19. Polyphenols are naturally occurring products with immunomodulatory activity, playing a relevant role in reducing inflammation and preventing the onset of serious chronic diseases. Mainly based on data collected before the appearance of SARS-CoV-2, polyphenols have been recently suggested as promising agents to fight COVID-19, and some clinical trials have already been approved with polyphenols to treat COVID-19. The aim of this review is to analyze and discuss the in vitro and in vivo research on the immunomodulatory activity of quercetin as a research model of polyphenols, focusing on research that addresses issues related to the dysregulated immune response in severe COVID-19. From this analysis, it emerges that although encouraging data are present, they are still insufficient to recommend polyphenols as potential immunomodulatory agents against COVID-19.

Quercetin for COVID-19 and DENGUE co-infection: a potential therapeutic strategy of targeting critical host signal pathways triggered by SARS-CoV-2 and DENV

Background

The clinical consequences of SARS-CoV-2 and DENGUE virus co-infection are not promising. However, their treatment options are currently unavailable. Current studies have shown that quercetin is both resistant to COVID-19 and DENGUE; this study aimed to evaluate the possible functional roles and underlying mechanisms of action of quercetin as a potential molecular candidate against COVID-19 and DENGUE co-infection.

Methods

We used a series of bioinformatics analyses to understand and characterize the biological functions, pharmacological targets and therapeutic mechanisms of quercetin in COVID-19 and DENGUE co-infection.

Results

We revealed the clinical characteristics of COVID-19 and DENGUE, including pathological mechanisms, key inflammatory pathways and possible methods of intervention, 60 overlapping targets related to the co-infection and the drug were identified, the protein–protein interaction (PPI) was constructed and TNFα, CCL-2 and CXCL8 could become potential drug targets. Furthermore, we disclosed the signaling pathways, biological functions and upstream pathway activity of quercetin in COVID-19 and DENGUE. The analysis indicated that quercetin could inhibit cytokines release, alleviate excessive immune responses and eliminate inflammation, through NF-κB, IL-17 and Toll-like receptor signaling pathway.

Conclusions

This study is the first to reveal quercetin as a pharmacological drug for COVID-19 and DENGUE co-infection. COVID-19 and DENGUE co-infection remain a potential threat to the world’s public health system. Therefore, we need innovative thinking to provide admissible evidence for quercetin as a potential molecule drug for the treatment of COVID-19 and DENGUE, but the findings have not been verified in actual patients, so further clinical drug trials are needed.

A topical formulation containing quercetin-loaded microcapsules protects against oxidative and inflammatory skin alterations triggered by UVB irradiation: enhancement of activity by microencapsulation

Ultraviolet B (UVB) irradiation causes free radical production, increase inflammation and oxidative stress, thus, supporting the use of antioxidants by topical administration as therapeutic approaches. Quercetin (QC) is a flavonoid with antioxidant activity, however, high liposolubility makes it difficult to remain in the viable skin layer. Thus, this study evaluated whether microencapsulation of QC would enhance its activity in comparison with the same dose of free QC (non-active dose) and unloaded-microcapsules added in formulation for topical administration in a mouse model of UVB irradiation targeting the skin. Topical formulation containing Quercetin-loaded microcapsules (TFcQCMC) presents physico-chemical (colour, consistence, phase separation and pH) and functional antioxidant stability at 4 °C, room temperature and 40 °C for 6 months. TFcQCMC inhibited the UVB-triggered depletion of antioxidants observed by GSH (reduced glutathione), ability to reduce iron, ability to scavenge 2,2'-azinobis radical and catalase activity. TFcQCMC also inhibited markers of oxidation (lipid hydroperoxides and superoxide anion production). Concerning inflammation, TFcQCMC reduced the production of inflammatory cytokines, matrix metalloproteinase-9 activity, skin edoema, collagen fibre damage, myeloperoxidase activity/neutrophil recruitment, mast cell and sunburn cell counts. The pharmacological activity of TFcQCMC was not shared by the same pharmaceutical form containing the same dose of free QC or unloaded control microcapsules.

A New Diterpene and Anti-inflammatory Sesquiterpene Lactones from Sigesbeckia orientalis

Sigesbeckia orientalis, more commonly referred to as Herba Sigesbeckiae or Xi Xian Cao in traditional Chinese medicine and hy thiêm in traditional Vietnamese medicine, is used in China and Vietnam to treat inflammatory diseases such as arthritis, rheumatism, and joint pain. In initial investigations, the dichloromethane extract from the aerial parts of S. orientalis showed distinct inhibitory effects on the release of interleukin-8 in human neutrophils. Therefore, the purpose of the present study was the phytochemical investigation of the bioactive dichloromethane extract and the in vitro analysis of the effects of the isolated compounds on interleukin-8, interleukin-1β, tumor necrosis factor-α, and monocyte chemoattractant protein 1 release, and surface expression of adhesion molecules (CD11a, CD11b, and CD62L) in lipopolysaccharide-stimulated human neutrophils to identify the active principle(s). The separation of the bioactive dichloromethane extract using various chromatographic techniques led to the isolation of nine compounds. Their chemical structures were elucidated from nuclear magnetic resonance and mass spectrometry data. One diterpene, 17(13 → 14)-abeo-ent-3S*,13S*,16-trihydroxystrob-8(15)-ene, was identified as a new natural product. Three germacranolide sesquiterpene lactones inhibited interleukin-8 production with IC₅₀ values between 1.6 and 6.3 µM, respectively, and tumor necrosis factor-α production with IC₅₀ values between 0.9 and 3.3 µM, respectively. Furthermore, they significantly inhibited interleukin-1β and monocyte chemoattractant protein 1 production and diminished the effects of lipopolysaccharide on the surface expression of the adhesion molecules CD11a, CD11b, and CD62L. These findings support the traditional use of S. orientalis in the treatment of inflammatory diseases.

Biomaterial-Driven Immunomodulation: Cell Biology-Based Strategies to Mitigate Severe Inflammation and Sepsis

Inflammation is an essential component of a wide variety of disease processes and oftentimes can increase the deleterious effects of a disease. Finding ways to modulate this essential immune process is the basis for many therapeutics under development and is a burgeoning area of research for both basic and translational immunology. In addition to developing therapeutics for cellular and molecular targets, the use of biomaterials to modify innate and adaptive immune responses is an area that has recently sparked significant interest. In particular, immunomodulatory activity can be engineered into biomaterials to elicit heightened or dampened immune responses for use in vaccines, immune tolerance, or anti-inflammatory applications. Importantly, the inherent physicochemical properties of the biomaterials play a significant role in determining the observed effects. Properties including composition, molecular weight, size, surface charge, and others affect interactions with immune cells (i.e., nano-bio interactions) and allow for differential biological responses such as activation or inhibition of inflammatory signaling pathways, surface molecule expression, and antigen presentation to be encoded. Numerous opportunities to open new avenues of research to understand the ways in which immune cells interact with and integrate information from their environment may provide critical solutions needed to treat a variety of disorders and diseases where immune dysregulation is a key inciting event. However, to elicit predictable immune responses there is a great need for a thorough understanding of how the biomaterial properties can be tuned to harness a designed immunological outcome. This review aims to systematically describe the biological effects of nanoparticle properties-separate from additional small molecule or biologic delivery-on modulating innate immune cell responses in the context of severe inflammation and sepsis. We propose that nanoparticles represent a potential polypharmacological strategy to simultaneously modify multiple aspects of dysregulated immune responses where single target therapies have fallen short for these applications. This review intends to serve as a resource for immunology labs and other associated fields that would like to apply the growing field of rationally designed biomaterials into their work.

Anti-inflammatory and anti-arthritic activity in extract from the leaves of Eriobotrya japonica

ETHNOPHARMACOLOGICAL RELEVANCE

The Eriobotrya japonica (EJ) is a Chinese medicinal plant that is currently grown in Brazil. E. japonica leaves infusion is traditionally used in the treatment of inflammation; however, there are few scientific studies showing the effects of these properties on joint articular and persistent experimental inflammation.

AIM OF THE STUDY

The present research had objective investigation of the effect of infusion obtained from leaves of E. japonica (EJLE) on acute and persistent experimental articular inflammation.

MATERIALS AND METHODS

The Swiss mice were treated orally with EJLE and analyzed for acute pleural inflammation (30, 100, and 300 mg/kg), paw edema induced by carrageenan (100 mg/kg), acute knee inflammation induced by zymosan (100 mg/kg), and persistent inflammation induced by Complete Freund's Adjuvant (CFA) (30 and 100 mg/kg). Mechanical hyperalgesia, cold and edema were analyzed.

RESULTS

The chromatographic analysis of EJLE revealed the presence of corosolic acid, oleanolic acid, and ursolic acid. EJLE presented anti-inflammatory activity in the pleurisy model, inhibiting leukocyte migration, protein extravasation and nitric oxide production. In the articular inflammation model, EJLE reduced the number of leukocytes in the joint cavity, paw edema and hyperalgesia (4 h after induction). In the persistent inflammation model induced by CFA, the extract reduced paw edema after 11 days of mechanical and cold hyperalgesia on day 6.

CONCLUSIONS

The EJLE has anti-inflammatory and antihyperalgesic potential in models of acute and persistent experimental articular inflammation, making this infusion a new possibility for complementary treating acute or chronic articular inflammatory diseases.

Hesperidin methyl chalcone interacts with NFκB Ser276 and inhibits zymosan-induced joint pain and inflammation, and RAW 264.7 macrophage activation

Arthritis can be defined as a painful musculoskeletal disorder that affects the joints. Hesperidin methyl chalcone (HMC) is a flavonoid with analgesic, anti-inflammatory, and antioxidant effects. However, its effects on a specific cell type and in the zymosan-induced inflammation are unknown. We aimed at evaluating the effects of HMC in a zymosan-induced arthritis model. A dose-response curve of HMC (10, 30, or 100 mg/kg) was performed to determine the most effective analgesic dose after intra-articular zymosan stimuli. Knee joint oedema was determined using a calliper. Leukocyte recruitment was performed by cell counting on knee joint wash as well as histopathological analysis. Oxidative stress was measured by colorimetric assays (GSH, FRAP, ABTS and NBT) and RT-qPCR (gp91^phox and HO-1 mRNA expression) performed. In vitro, oxidative stress was assessed by DCFDA assay using RAW 264.7 macrophages. Cytokine production was evaluated in vivo and in vitro by ELISA. In vitro NF-κB activation was analysed by immunofluorescence. We observed HMC reduced mechanical hypersensitivity and knee joint oedema, leukocyte recruitment, and pro-inflammatory cytokine levels. We also observed a reduction in zymosan-induced oxidative stress as per increase in total antioxidant capacity and reduction in gp91^phox and increase in HO-1 mRNA expression. Accordingly, total ROS production and macrophage NFκB activation were diminished. HMC interaction with NFκB p65 at Ser276 was revealed using molecular docking analysis. Thus, data presented in this work suggest the usefulness of HMC as an analgesic and anti-inflammatory in a zymosan-induced arthritis model, possibly by targeting NFκB activation in macrophages.

Therapeutic Potential of Flavonoids in Pain and Inflammation: Mechanisms of Action, Pre-Clinical and Clinical Data, and Pharmaceutical Development

Pathological pain can be initiated after inflammation and/or peripheral nerve injury. It is a consequence of the pathological functioning of the nervous system rather than only a symptom. In fact, pain is a significant social, health, and economic burden worldwide. Flavonoids are plant derivative compounds easily found in several fruits and vegetables and consumed in the daily food intake. Flavonoids vary in terms of classes, and while structurally unique, they share a basic structure formed by three rings, known as the flavan nucleus. Structural differences can be found in the pattern of substitution in one of these rings. The hydroxyl group (-OH) position in one of the rings determines the mechanisms of action of the flavonoids and reveals a complex multifunctional activity. Flavonoids have been widely used for their antioxidant, analgesic, and anti-inflammatory effects along with safe preclinical and clinical profiles. In this review, we discuss the preclinical and clinical evidence on the analgesic and anti-inflammatory proprieties of flavonoids. We also focus on how the development of formulations containing flavonoids, along with the understanding of their structure-activity relationship, can be harnessed to identify novel flavonoid-based therapies to treat pathological pain and inflammation.

Immunomodulating action of the 3-phenylcoumarin derivative 6,7-dihydroxy-3-[3',4'-methylenedioxyphenyl]-coumarin in neutrophils from patients with rheumatoid arthritis and in rats with acute joint inflammation

OBJECTIVE

To examine whether free (3-PD-5_free) and/or liposomal (3-PD-5_lipo) 6,7-dihydroxy-3-[3',4'-methylenedioxyphenyl]-coumarin (3-PD-5) (1) modulate the effector functions of neutrophils from patients with rheumatoid arthritis under remission (i-RA) and with active disease (a-RA), in vitro; and (2) exert anti-inflammatory effect in a rat model of zymosan-induced acute joint inflammation.

METHODS AND RESULTS

Incorporation of 3-PD-5 into unilamellar liposomes of soya phosphatidylcholine and cholesterol was efficient (57.5 ± 7.9%) and yielded vesicles with low diameter (133.7 ± 18.4 nm), polydispersity index (0.39 ± 0.06), and zeta potential (- 1.22 ± 0.34 mV). 3-PD-5_free (1 µM) and 3-PD-5_lipo (3 µM) equally suppressed elastase release and reactive oxygen species generation in neutrophils from healthy subjects and i-RA and a-RA patients, stimulated with immune complexes. 3-PD-5_free (20 µM) suppressed the release of neutrophil extracellular traps and chemotaxis in vitro, without clear signs of cytotoxicity. 3-PD-5_lipo (1.5 mg/kg, i.p.) diminished joint edema and synovial infiltration of total leukocytes and neutrophils, without changing the synovial levels of TNF-α, IL-1β, and IL-6.

CONCLUSION

Altogether, the results reported herein indicate that 3-PD-5 is a promising modulator of the early stages of acute joint inflammation that can help to diminish not only excessive neutrophil infiltration in the synovia but also neutrophil activation and its outcomes in RA patients.

Eupatoriopicrin Inhibits Pro-inflammatory Functions of Neutrophils via Suppression of IL-8 and TNF-alpha Production and p38 and ERK 1/2 MAP Kinases

During chronic inflammation, neutrophils acting locally as effector cells not only activate antibacterial defense but also promote the inflammatory response. Interleukin 8 (IL-8), the main cytokine produced by activated neutrophils, positively correlates with the severity of respiratory tract diseases. By screening European plants traditionally used for treating respiratory tract diseases, we found that extracts of aerial parts of Eupatorium cannabinum inhibit IL-8 release from neutrophils. Using bioassay-guided fractionation, we identified five sesquiterpene lactones, eupatoriopicrin (1), 5'-deoxyeupatoriopicrin (2), hiyodorilactone A (3), 3-hydroxy-5'- O-acetyleupatoriopicrin = hiyodorilactone D (4), and hiyodorilactone B (5), that efficiently (IC₅₀ < 1 μM) inhibited IL-8 and TNF-α release in lipopolysaccharide (LPS)-stimulated human neutrophils. Moreover, all these sesquiterpene lactones suppressed the adhesion of human neutrophils to an endothelial monolayer by downregulating the expression of the β2 integrin CD11b/CD18 on the neutrophil surface. Furthermore, eupatoriopicrin efficiently suppressed LPS-induced phosphorylation of p38 MAPK and ERK and attenuated neutrophil infiltration in the thioglycolate-induced peritonitis model in mice. Altogether, these results demonstrate the potential of the sesquiterpene lactone eupatoriopicrin as a lead substance for targeting inflammation.

Lignans From Forsythia x Intermedia Leaves and Flowers Attenuate the Pro-inflammatory Function of Leukocytes and Their Interaction With Endothelial Cells

Aim of the study: Taking into account that overactivated leukocytes are an important factor in the development of many chronic diseases, we investigated the activity of phytochemically characterized (HPLC-DAD-MSⁿ) extracts from forsythia leaves and flowers on the pro- and anti-inflammatory functions of leukocytes (effects on IL-1β, IL-8, TNF-α, and TGFβ release) and their adherence to endothelial cells. Using bio-guided fractionation, we isolated the active compounds and determined their biological activity, and we included the positive control quercetin. Methods: The effect on IL-1β, TNF-α, IL-8, and TGF-α production by leukocytes was measured by enzyme-linked immunosorbent assay (ELISA). The surface expression of adhesion molecules was analyzed with flow cytometry, and the neutrophil attachment to the endothelial cells was assessed fluorimetrically. The effects on p38MAPK, ERK1/2 and JNK phosphorylation were determined using western blots. Results: Leaf extracts had the effect of decreasing TNF-α production in neutrophils and monocyte/macrophage cells. The bio-guided fractionation led to the isolation of the following lignan aglycones: (+)-pinoresinol, (+)-epipinoresinol, (-)-matairesinol, (+)-phillygenin, and (-)-arctigenin. Only phillygenin was able to stimulate the anti-inflammatory function of macrophages by inducing TGF-β release and IL-10 receptor surface expression. Arctigenin, phillygenin, and a metabolite produced by the gut microbiota, enterolactone, decreased TNF-α and IL-1β production and neutrophil adhesion to endothelial cells, probably by attenuating the p38 and ERK kinase pathways. Conclusion:Forsythia x intermedia is a valuable source of active lignans, which may be potential candidates for treating inflammatory diseases that are associated with the excessive production of cytokines such as TNF-α and IL-1β.

Quercetin attenuates zymosan-induced arthritis in mice

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by articular lesions, recruitment of inflammatory cells and increased levels of pro-inflammatory cytokine. The intra-articular administration of zymosan is an experimental model that promotes inflammatory parameters resembling RA. Therefore, this model was used to investigate the efficacy of quercetin as a treatment of articular inflammation. Treatment with quercetin dose-dependently reduced zymosan-induced hyperalgesia, articular edema and the recruitment of neutrophils to the knee joint cavity. Histological analysis confirmed that quercetin inhibited zymosan-induced arthritis. The treatment with quercetin also inhibited zymosan-induced depletion of reduced glutathione (GSH) levels, TNFα and IL-1β production, and gp91^phox, prepro-endothelin-1 (preproET-1), and cyclooxygenase-2 mRNA expression. These molecular effects of quercetin were related to the inhibition of the nuclear factor kappa-B and induction of Nuclear factor erythroid 2- related factor (Nrf2)/home oxygenase (HO-1) pathway. Thus, quercetin exerted anti-inflammatory, analgesic and antioxidant effects in experimental arthritis, suggesting quercetin is a possible candidate for arthritis treatment.

The 3-phenylcoumarin derivative 6,7-dihydroxy-3-[3',4'-methylenedioxyphenyl]-coumarin downmodulates the FcγR- and CR-mediated oxidative metabolism and elastase release in human neutrophils: Possible mechanisms underlying inhibition of the formation and release of neutrophil extracellular traps

In this study, we report the ability of a set of eight 3-phenylcoumarin derivatives bearing 6,7- or 5,7-dihydroxyl groups, free or acetylated, bound to the benzopyrone moiety, to modulate the effector functions of human neutrophils. In general, (i) 6,7-disubstituted compounds (5, 6, 19, 20) downmodulated the Fcγ receptor-mediated neutrophil oxidative metabolism more strongly than 5,7-disubstituted compounds (21, 22, 23, 24), and (ii) hydroxylated compounds (5, 19, 21, 23) downmodulated this neutrophil function more effectively than their acetylated counterparts (6, 20, 22, 24, respectively). Compounds 5 (6,7-dihydroxy-3-[3',4'-methylenedioxyphenyl]-coumarin) and 19 (6,7-dihydroxy-3-[3',4'-dihydroxyphenyl]-coumarin) effectively downmodulated the neutrophil oxidative metabolism elicited via Fcγ and/or complement receptors. Compound 5 also downmodulated the immune complex-stimulated phagocytosis, degranulation of elastase, and production and release of neutrophil extracellular traps, as well as the human neutrophil chemotaxis towards n-formyl-methionyl-leucyl-phenylalanine, without altering the expression level of formyl peptide receptor type 1. Both compounds 5 and 19 did not impair the neutrophil capacity to recognize and kill Candida albicans. Docking calculations revealed that compounds 5 and 19 directly interacted with three catalytic residues - Gln-91, His-95, and Arg-239 - inside the myeloperoxidase active site. Together, these findings indicate that (i) inhibition of reactive oxygen species generation and degranulation of elastase are closely associated with downmodulation of release of neutrophil extracellular traps; and (ii) compound 5 can be a prototype for the development of novel immunomodulating drugs to treat immune complex-mediated inflammatory diseases.

The flavonoid quercetin inhibits titanium dioxide (TiO2)-induced chronic arthritis in mice

Titanium dioxide (TiO₂) is a common component of orthopedic prosthesis. However, prosthesis wear releases TiO₂, which induces inflammation and osteolysis in peri-prosthetic tissues. Quercetin is a flavonoid widely present in human diet, which presents biological activities such as antinociceptive, anti-inflammatory and antioxidant effects. Therefore, the effect of intraperitoneal treatment with quercetin in TiO₂-induced arthritis model was evaluated. In the first set of experiments, mice received injection of TiO₂ (0.1-3 mg/knee joint) and articular mechanical hyperalgesia, edema and histopathology analysis were performed in a 30 days protocol. The dose of 3 mg of TiO₂ showed the most harmful effect, and was chosen to the following experiments. Subsequently, mice received 3 mg of TiO₂ followed by post-treatment with quercetin during 30 days. Quercetin (10-100 mg/kg) inhibited in a dose-dependent manner TiO₂-induced knee joint mechanical hyperalgesia, edema and leukocyte recruitment and did not induce damage in major organs such as liver, kidney and stomach. The dose of 30 mg/kg was chosen for the subsequent analysis, and reduced histopathological changes such as leukocyte infiltration, vascular proliferation and synovial hyperplasia (pannus formation) on day 30 after TiO₂ challenge. The protective analgesic and anti-inflammatory mechanisms of quercetin included the inhibition of TiO₂-induced neutrophil and macrophage recruitment, proteoglycan degradation, oxidative stress, cytokine production (TNF-α, IL-1β, IL-6, and IL-10), COX-2 mRNA expression, and bone resorption as well as activation of Nrf2/HO-1 signaling pathway. These results demonstrate the potential therapeutic applicability of the dietary flavonoid quercetin to reduce pain and inflammatory damages associated with prosthesis wear process-induced arthritis.

MicroRNAs in neutrophils: potential next generation therapeutics for inflammatory ailments

Neutrophils play fundamental roles in both acute and chronic inflammatory conditions, and directly contribute to the immune pathologies in both infectious and autoimmune ailments. MicroRNAs (miRs) regulate homeostasis in health and disease by fine tuning the expression of a network of genes through post-transcriptional regulation. Many miRs are expressed in restricted tissues, regulated by stress and disease, and are emerging as mediators for intercellular communication. MiR profiles have been recently utilized as biomarkers for diagnosis and prognostic purposes. In addition, several miRs are in clinical development for various diseases. A short list of miRs that regulate hematopoiesis and neutrophil development is identified. Unfortunately, very limited information is available regarding how miRs regulate neutrophil migration and activation in vivo. Extensive future work is required, especially in animal models such as mice, to illustrate the pivotal and complex miR-mediated regulatory network. In addition, zebrafish, a vertebrate model organism with conserved innate immunity, potentiated by the availability of imaging and genetic tools, will provide a platform for rapid discovery and characterization of miRs that are relevant to neutrophilic inflammation. Advances in this field are expected to provide the foundation for highly selective miR-based therapy to manipulate neutrophils in infection and inflammatory disorders.

Quercetin inhibits gout arthritis in mice: induction of an opioid-dependent regulation of inflammasome

We investigated the anti-inflammatory and analgesic effects of quercetin in monosodium urate crystals (MSU)-induced gout arthritis, and the sensitivity of quercetin effects to naloxone, an opioid receptor antagonist. Mice were treated with quercetin, and mechanical hyperalgesia was assessed at 1-24 h after MSU injection. In vivo, leukocyte recruitment, cytokine levels, oxidative stress, NFκB activation, and gp91phox and inflammasome components (NLRP3, ASC, Pro-caspase-1, and Pro-IL-1β) mRNA expression by qPCR were determined in the knee joints at 24 h after MSU injection. Inflammasome activation was determined, in vitro, in lipopolysaccharide-primed macrophages challenged with MSU. Quercetin inhibited MSU-induced mechanical hyperalgesia, leukocyte recruitment, TNFα and IL-1β production, superoxide anion production, inflammasome activation, decrease of antioxidants levels, NFκB activation, and inflammasome components mRNA expression. Naloxone pre-treatment prevented all the inhibitory effects of quercetin over MSU-induced gout arthritis. These results demonstrate that quercetin exerts analgesic and anti-inflammatory effect in the MSU-induced arthritis in a naloxone-sensitive manner.

Effects of purified anthocyanin supplementation on platelet chemokines in hypocholesterolemic individuals: a randomized controlled trial

Background

It is becoming increasingly evident that platelet chemokines are involved in distinct aspects of atherosclerosis. The aim of this study was to examine the effects of long-term supplementation with purified anthocyanins on platelet chemokines in hypercholesterolemic individuals and to identify correlations of decreased platelet chemokine levels with serum lipid and inflammatory marker levels.

Methods

A total of 146 hypercholesterolemic individuals were recruited and treated with 320 mg of purified anthocyanins (n = 73) or a placebo (n = 73) daily for 24 weeks in this randomized, double-blind, placebo-controlled trial.

Results

Anthocyanin supplementation for 24 weeks significantly decreased the plasma CXCL7 (–12.32% vs. 4.22%, P = 0.001), CXCL5 (–9.95% vs. 1.93%, P = 0.011), CXCL8 (–6.07% vs. 0.66%, P = 0.004), CXCL12 (–8.11% vs. 5.43%, P = 0.023) and CCL2 levels (–11.63% vs. 12.84%, P = 0.001) compared with the placebo. Interestingly, the decreases in the CXCL7 and CCL2 levels were both positively correlated with the decreases in the serum low-density lipoprotein-cholesterol (LDL-C), high-sensitivity C-reactive protein (hsCRP) and interleukin-1β (IL-1β) levels after anthocyanin supplementation for 24 weeks. The decrease in the CXCL8 level was negatively correlated with the increase in the how-density lipoprotein-cholesterol (HDL-C) level and was positively correlated with the decrease in the soluble P-selectin (sP-selectin) level in the anthocyanin group. In addition, a positive correlation was observed between the decreases in the CXCL12 and tumornecrosis factor-α (TNF-α) levels after anthocyanin supplementation. However, the plasma CXCL4L1, CXCL1, macrophage migration inhibitory factor (MIF) and human plasminogen activator inhibitor 1 (PAI-1) levels did not significantly change following anthocyanin supplementation.

Conclusions

The present study supports the notion that platelet chemokines are promising targets of anthocyanins in the prevention of atherosclerosis.

Trial registration

ChiCTR-TRC-08000240. Registered: 10 December 2008.

Eugenia aurata and Eugenia punicifolia HBK inhibit inflammatory response by reducing neutrophil adhesion, degranulation and NET release

BACKGROUND

Eugenia spp. are used in popular medicine in the treatment of pain, diabetes, intestinal disorders and cough. The aim of the work is to evaluate, ex vivo and in vivo, the anti-inflammatory activity of the hydroethanolic extracts of the leaves of Eugenia aurata (EA) and Eugenia punicifolia HBK (EP) upon neutrophils.

METHODS

Ex vivo, isolated human neutrophils were sensitized by Eugenia extracts (0.1-1000 μg/mL) and stimulated by PMA. In these conditions, different neutrophil activities related to inflammatory process were measured: adhesion, degranulation and NET release. Neutrophil viability and tumor line cells were monitored. In vivo, neutrophil influx was evaluated by peritonitis model performed in mice pretreated with different concentrations of Eugenia extracts. Phytochemical profile was assessed by mass spectrometry.

RESULTS

Ex vivo, EA and EP (1000 μg/mL) reduced cell adhesion and degranulation, respectively. NET release was inhibited by EA and EP. Anti-inflammatory activities occurred in the absence of cytotoxicity. In vivo, both EA as EP inhibited neutrophil migration. The phytochemical profile revealed that EA contains myricitrin, rutin, quinic acid and quercetin derivatives. EP presents gallic acid, quercetin derivatives, syringic acid, ellagic acid, monogalloyl-glucose, glycosyringic acid, mudanoside B, HHDP glucose isomer and digalloylglucose isomer. EA and EP inhibit neutrophil migration by different pathways.

CONCLUSION

Different chemical compositions may explain the anti-inflammatory effects described herein for EA and EP. Both extracts inhibit NET release but only EA reduces cell adhesion whereas EP decreases elastase secretion. This work contributes to the elucidation of cellular mechanisms related to the anti-inflammatory activity for leaves of E. aurata and E. punicifolia HBK.

Neutrophils and arthritis: Role in disease and pharmacological perspectives

The inflammatory response in the joint can induce an intense accumulation of leukocytes in the tissue that frequently results in severe local damage and loss of function. Neutrophils are essential cells to combat many pathogens, but their arsenal can contribute or aggravate articular inflammation. Here we summarized some aspects of neutrophil biology, their role in inflammation and indicated how the modulation of neutrophil functions could be useful for the treatment of different forms of arthritis.

Quercetin reduces Ehrlich tumor-induced cancer pain in mice

Cancer pain directly affects the patient's quality of life. We have previously demonstrated that the subcutaneous administration of the mammary adenocarcinoma known as Ehrlich tumor induces pain in mice. Several studies have shown that the flavonoid quercetin presents important biological effects, including anti-inflammatory, antioxidant, analgesic, and antitumor activity. Therefore, the analgesic effect and mechanisms of quercetin were evaluated in Ehrlich tumor-induced cancer pain in mice. Intraperitoneal (i.p.) treatments with quercetin reduced Ehrlich tumor-induced mechanical and thermal hyperalgesia, but not paw thickness or histological alterations, indicating an analgesic effect without affecting tumor growth. Regarding the analgesic mechanisms of quercetin, it inhibited the production of hyperalgesic cytokines IL-1β and TNFα and decreased neutrophil recruitment (myeloperoxidase activity) and oxidative stress. Naloxone (opioid receptor antagonist) inhibited quercetin analgesia without interfering with neutrophil recruitment, cytokine production, and oxidative stress. Importantly, cotreatment with morphine and quercetin at doses that were ineffective as single treatment reduced the nociceptive responses. Concluding, quercetin reduces the Ehrlich tumor-induced cancer pain by reducing the production of hyperalgesic cytokines, neutrophil recruitment, and oxidative stress as well as by activating an opioid-dependent analgesic pathway and potentiation of morphine analgesia. Thus, quercetin treatment seems a suitable therapeutic approach for cancer pain that merits further investigation.

The superoxide anion donor, potassium superoxide, induces pain and inflammation in mice through production of reactive oxygen species and cyclooxygenase-2

It is currently accepted that superoxide anion (O₂^•−) is an important mediator in pain and inflammation. The role of superoxide anion in pain and inflammation has been mainly determined indirectly by modulating its production and inactivation. Direct evidence using potassium superoxide (KO₂), a superoxide anion donor, demonstrated that it induced thermal hyperalgesia, as assessed by the Hargreaves method. However, it remains to be determined whether KO₂ is capable of inducing other inflammatory and nociceptive responses attributed to superoxide anion. Therefore, in the present study, we investigated the nociceptive and inflammatory effects of KO₂. The KO₂-induced inflammatory responses evaluated in mice were: mechanical hyperalgesia (electronic version of von Frey filaments), thermal hyperalgesia (hot plate), edema (caliper rule), myeloperoxidase activity (colorimetric assay), overt pain-like behaviors (flinches, time spent licking and writhing score), leukocyte recruitment, oxidative stress, and cyclooxygenase-2 mRNA expression (quantitative PCR). Administration of KO₂ induced mechanical hyperalgesia, thermal hyperalgesia, paw edema, leukocyte recruitment, the writhing response, paw flinching, and paw licking in a dose-dependent manner. KO₂ also induced time-dependent cyclooxygenase-2 mRNA expression in the paw skin. The nociceptive, inflammatory, and oxidative stress components of KO₂-induced responses were responsive to morphine (analgesic opioid), quercetin (antioxidant flavonoid), and/or celecoxib (anti-inflammatory cyclooxygenase-2 inhibitor) treatment. In conclusion, the well-established superoxide anion donor KO₂ is a valuable tool for studying the mechanisms and pharmacological susceptibilities of superoxide anion-triggered nociceptive and inflammatory responses ranging from mechanical and thermal hyperalgesia to overt pain-like behaviors, edema, and leukocyte recruitment.

Bothrops jararacussu snake venom-induces a local inflammatory response in a prostanoid- and neutrophil-dependent manner

Local tissue reactions provoked by Bothrops venoms are characterized by edema, hemorrhage, pain, and inflammation; however, the mechanisms of tissue damage vary depending upon the species of snake. Here, we investigated the mechanisms involved in the local inflammatory response induced by the Bothrops jararacussu venom (BjcuV). Female Swiss mice were injected with either saline, BjcuV (0.125-8 μg/paw) or loratadine (an H1 receptor antagonist), compound 48/80 (for mast cell depletion), capsaicin (for C-fiber desensitization), infliximab (an anti-TNF-α antibody), indomethacin (a non-specific COX inhibitor), celecoxib (a selective COX-2 inhibitor) or fucoidan (a P- and L-selectins modulator) given before BjcuV injection. Paw edema was measured by plethysmography. In addition, paw tissues were collected for the measurement of myeloperoxidase activity, TNF-α and IL-1 levels, and COX-2 immunoexpression. The direct chemotactic effect of BjcuV and the in vitro calcium dynamic in neutrophils were also investigated. BjcuV caused an edematogenic response with increased local production of TNF-α and IL-1β as well as COX-2 expression. Both edema and neutrophil migration were prevented by pretreatment with indomethacin, celecoxib or fucoidan. Furthermore, BjcuV induced a direct in vitro neutrophil chemotaxis by increasing intracellular calcium. Therefore, BjcuV induces an early onset edema dependent upon prostanoid production and neutrophil migration.

Anethole and eugenol reduce in vitro and in vivo leukocyte migration induced by fMLP, LTB4, and carrageenan

The aim of this study was to investigate the effect of anethole (AN) and eugenol (EUG) on leukocyte migration using in vitro chemotaxis and in situ microcirculation assays. BALB/c mice were used for the in vitro chemotaxis assay, and Wistar rats for the in situ microcirculation assay. We evaluated (a) the in vitro leukocyte migration in response to chemotactic factors (formyl-methionyl-leucyl-phenylalanine [fMLP] and leukotriene B4 [LTB4]) and (b) the rolling, adhesion, and migration of leukocytes induced by an injection of carrageenan (100 µg/cavity) into the scrotum of the animal. In the in vitro chemotaxis assay, AN and EUG at doses of 1, 3, 9, and 27 µg/ml significantly inhibited leukocyte migration when stimulated by the chemotactic agents fMLP and LTB4. In the in situ microcirculation assay, AN at doses of 125 and 250 mg/kg and EUG at a dose of 250 mg/kg significantly decreased the number of leukocytes that rolled, adhered, and migrated to perivascular tissue. The results indicate that AN and EUG exert inhibitory effects on leukocyte migration, highlighting their possible use to diminish excessive leukocyte migration in the inflammatory process.

Quercetin-loaded microcapsules ameliorate experimental colitis in mice by anti-inflammatory and antioxidant mechanisms

Quercetin (1) is an anti-inflammatory and antioxidant flavonoid. However, the oral administration of 1 did not lead to beneficial effects in experimental animal colitis models, which involve cytokines and oxidative stress. A possible explanation is that the absorption profile of 1 prevents its activity. Therefore, it was reasoned that the controlled release of 1 would improve its therapeutic effect. Thus, the therapeutic effect and mechanisms of 1-loaded microcapsules in acetic acid-induced colitis in mice were evaluated. Microcapsules were prepared using pectin/casein polymer and 1. The oral administration of 1-loaded microcapsules decreased neutrophil recruitment, attenuated histological alterations, and reduced macroscopical damage, edema, and IL-1β and IL-33 production in the colon samples. Microcapsules loaded with 1 also prevented the reduction of anti-inflammatory cytokine IL-10 and the antioxidant capacity of the colon. These preclinical data indicate that pectin/casein polymer microcapsules loaded with 1 improved the anti-inflammatory and antioxidant effects of 1 compared to the nonencapsulated drug. Therefore, quercetin seems to be a promising active molecule in inflammatory bowel disease if provided with adequate controlled release.

Neutrophil chemotaxis within a competing gradient of chemoattractants

The dynamics of neutrophil chemotaxis under competing chemoattractant gradients was studied using a microfluidic platform. This microfluidic platform, which establishes a stable and dynamic gradient of chemoattractants across a cell culture chamber, enabled the investigation of human neutrophil migration patterns in the presences of four different chemoattractants (leukotriene B(4), chemokine C-X-C motif ligands 2 and 8, and fMLP) and competing gradients of all pairwise combinations. The migration patterns for individual cells were tracked and quantitatively analyzed, and the results suggest a hierarchy among these chemoattractants of fMLP > CXCL8 > CXCL2 > leukotriene B(4). In all conditions, over 60% of neutrophils exposed to a competing gradient move toward the stronger signal though the weaker chemoattractant still influences neutrophil motility. These results yield insight about how each chemoattractant contributes to overall neutrophil chemotaxis within complex physiological environments.

Perturbation of host cell cytoskeleton by cranberry proanthocyanidins and their effect on enteric infections

Cranberry-derived compounds, including a fraction known as proanthocyanidins (PACs) exhibit anti-microbial, anti-infective, and anti-adhesive properties against a number of disease-causing organisms. In this study, the effect of cranberry proanthocyanidins (CPACs) on the infection of epithelial cells by two enteric bacterial pathogens, enteropathogenic Escherichia coli (EPEC) and Salmonella Typhimurium was investigated. Immunofluorescence data showed that actin pedestal formation, required for infection by enteropathogenic Escherichia coli (EPEC), was disrupted in the presence of CPACs. In addition, invasion of HeLa cells by Salmonella Typhimurium was significantly reduced, as verified by gentamicin protection assay and immunofluorescence. CPACs had no effect on bacterial growth, nor any detectable effect on the production of bacterial effector proteins of the type III secretion system. Furthermore, CPACs did not affect the viability of host cells. Interestingly, we found that CPACs had a potent and dose-dependent effect on the host cell cytoskeleton that was evident even in uninfected cells. CPACs inhibited the phagocytosis of inert particles by a macrophage cell line, providing further evidence that actin-mediated host cell functions are disrupted in the presence of cranberry CPACs. Thus, although CPAC treatment inhibited Salmonella invasion and EPEC pedestal formation, our results suggest that this is likely primarily because of the perturbation of the host cell cytoskeleton by CPACs rather than an effect on bacterial virulence itself. These findings have significant implications for the interpretation of experiments on the effects of CPACs on bacteria-host cell interactions.