Grape seed proanthocyanidin extract (GSPE) differentially regulates Foxp3(+) regulatory and IL-17(+) pathogenic T cell in autoimmune arthritis

Nutraceuticals as Modulators of Immune Function: A Review of Potential Therapeutic Effects

Dietary supplementation with nutraceuticals can promote optimal immune system activation, modulating different pathways that enhance immune defenses. Therefore, the immunity-boosting effects of nutraceuticals encompass not only immunomodulatory but also antioxidant, antitumor, antiviral, antibacterial, and antifungal properties, with therapeutic effects against diverse pathological conditions. However, the complexity of the pathways that regulate the immune system, numerous mechanisms of action, and heterogeneity of the immunodeficiencies, and subjects treated make their application in the clinical field difficult. Some nutraceuticals appear to safely improve immune system function, particularly by preventing viral and bacterial infections in specific groups, such as children, the elderly, and athletes, as well as in frail patients, such as those affected by autoimmune diseases, chronic diseases, or cancer. Several nutraceuticals, such as vitamins, mineral salts, polyunsaturated omega-3 fatty acids, many types of phytocompounds, and probiotic strains, have the most consolidated evidence in humans. In most cases, further large and long-term randomized clinical trials are needed to confirm the available preliminary positive data.

Proanthocyanidins: A novel approach to Henoch‑Schonlein purpura through balancing immunity and arresting oxidative stress via TLR4/MyD88/NF‑κB signaling pathway (Review)

Henoch-Schonlein purpura (HSP), a recurrent and immunoglobulin (Ig)A-mediated vasculitis, presents not only as skin lesions but also as systemic involvement that can be life-threatening. Although the etiology of HSP remains unknown, immune imbalance and oxidative stress (OS) are primary contributors to its pathogenesis, alongside the abnormal activation of Toll-like receptor (TLR)/myeloid differentiation primary response gene 88 (MyD88)/nuclear factor-κB (NF-κB) pathway. TLRs, especially TLR4, stimulate downstream signaling molecules such as NF-κB and proinflammatory cytokines, which are released when TLRs combine with the key adapter molecule MyD88. This leads to the activation of T helper (Th) cell 2/Th17 and overproduction of reactive oxygen species (ROS). The function of regulatory T (Treg) cells is suppressed in the process. Th17/Treg imbalance then produces various inflammatory cytokines to promote proliferation and differentiation of B cells and the secretion of antibodies. IgA is secreted, and it binds to vascular endothelial surface receptors where the complex induces injury of the vascular endothelial cells. Additionally, excessive ROS creates OS that leads to an inflammatory response and vascular cell apoptosis or necrosis, thereby contributing to vascular endothelial damage and HSP occurrence. Proanthocyanidins are active compounds naturally enriched in fruits, vegetables and plants. Proanthocyanidins have diverse properties, including anti-inflammatory, antioxidant, antibacterial, immunoregulatory, anticarcinogenic and vascular protective effects. Proanthocyanidins are used in the management of various diseases. Proanthocyanidins regulate T cells, equilibrate immunity and arrest OS by inhibiting the TLR4/MyD88/NF-κB signaling pathway. Considering the pathogenesis of HSP and the properties of proanthocyanidins, the present study hypothesized that these compounds may potentially lead to HSP recovery through modulating the immune equilibrium and preventing OS by inhibiting the TLR4/MyD88/NF-κB pathway. To the best of our knowledge, however, little is known about the positive effects of proanthocyanidins against HSP. The present review summarizes the potential of proanthocyanidins to treat HSP.

Therapeutic potential of targeting IL-17 and its receptor signaling in neuroinflammation

T helper 17 cells are thought to significantly contribute to the neuroinflammation process during neurogenerative diseases via their signature cytokine, interleukin (IL)-17. Recently, an emerging key role of IL-17 and its receptors has been documented in inflammatory and autoimmune diseases. The clinical studies conducted on patients with neurodegenerative disease have also shown an increase in IL-17 levels in serum as well as cerebrospinal fluid samples. Therapeutic targeting of either IL-17 receptors or direct IL-17 neutralizing antibodies has shown a promising preclinical and clinical proof of concept for treating chronic autoimmune neurodegenerative diseases such as multiple sclerosis. Thus, IL-17 and its receptors have a central role in regulation of neuroinflammation and can be considered as one of the major therapeutic targets in chronic neuroinflammatory diseases.

The protective effect of proanthocyanidins on the psoriasis-like cell models via PI3K/AKT and HO-1

Background

Inflammation and oxidative stress (OS) are important contributors to psoriasis pathogenesis. Proanthocyanidins (PCs) have anti-inflammatory and anti-oxidative activities. Previously, we discovered that PCs alleviated psoriasis-like mice symptoms, likely via mitigating inflammation and OS damage.

Objective

To elucidate the protective mechanism underlying PCs against the damage of TNF-ɑ-induced psoriasis-like cell models.

Methods

Psoriasis-like cell models were established with 7.5 ng/mL TNF-ɑ and then subjected to different-concentrations PCs treatment. Finally, inflammatory and oxidative parameters were determined. Besides, LY294002 (PI3K inhibitor) and ZnPP (HO-1 inhibitor) were employed to investigate the roles of PI3K/AKT and HO-1 in PCs against psoriasis-like cell models.

Results

After TNF-α treatment, cells organized tightly and proliferated greatly (P<0.01); HO-1 expression dropped obviously, along with the increased OS/inflammatory indicators and the decreased antioxidants (P<0.05); consequently, psoriasis-like cell models were well established. In the presence of PCs, nevertheless, the proliferation rate and number of psoriasis-like cells evidently decreased (P<0.01), accompanied with enhanced HO-1 and antioxidants, and lowered OS/inflammatory indicators as well as phosphorylated JAK2/STAT3/PI3/AKT (P<0.01). Similar changes appeared after LY294002 pretreatment, regardless of PCs or not. But after ZnPP pretreatment with or without PCs, the opposite occurred.

Conclusion

The study reveals that PCs can suppress psoriasis-like cell proliferation and reduce inflammatory/OS damage through PI3K/AKT inhibition and HO-1 activation, thus promising a candidate for PCs in treating psoriasis.

Tackling the Future Pandemics: Broad-Spectrum Antiviral Agents (BSAAs) Based on A-Type Proanthocyanidins

A-type proanthocyanidins (PAC-As) are plant-derived natural polyphenols that occur as oligomers or polymers of flavan-3-ol monomers, such as (+)-catechin and (-)-epicatechin, connected through an unusual double A linkage. PAC-As are present in leaves, seeds, flowers, bark, and fruits of many plants, and are thought to exert protective natural roles against microbial pathogens, insects, and herbivores. Consequently, when tested in isolation, PAC-As have shown several biological effects, through antioxidant, antibacterial, immunomodulatory, and antiviral activities. PAC-As have been observed in fact to inhibit replication of many different human viruses, and both enveloped and non-enveloped DNA and RNA viruses proved sensible to their inhibitory effect. Mechanistic studies revealed that PAC-As cause reduction of infectivity of viral particles they come in contact with, as a result of their propensity to interact with virion surface capsid proteins or envelope glycoproteins essential for viral attachment and entry. As viral infections and new virus outbreaks are a major public health concern, development of effective Broad-Spectrum Antiviral Agents (BSAAs) that can be rapidly deployable even against future emerging viruses is an urgent priority. This review summarizes the antiviral activities and mechanism of action of PAC-As, and their potential to be deployed as BSAAs against present and future viral infections.

The immunoregulatory effects of natural products on psoriasis via its action on Th17 cells versus regulatory T cells balance

Psoriasis is an incurable, chronic inflammatory disease, which brings a substantial burden on individuals and society. Currently, the treatment of psoriasis has entered the era of biologics, but its highly targeting of inflammatory mediators may enable the immune response to circumvent the blockade, leading to disease recurrence, or other clinical and immunological characteristics. Therefore, the discovery of new therapies that have the ability of multidirectional regulation on immunity and maintain the dynamic balance of immunity in psoriasis, may be the key to the treatment of the disease. Natural products extracted from herbal medicines have synergistic effects to alleviate psoriasis and its comorbidities because of their structural diversity and multiple active mechanisms. To date, the characteristics of natural products regulating T helper 17 (Th17) cells/regulatory T (Treg) cells balance in the treatment of psoriasis have attracted more and more attention from basic and clinical studies. In this review, we systematically introduced the natural products regulating the balance of Th17/Treg and their specific mechanism of action, finding Datura metel L, Grape seed proanthocyanidin extract (GSPE), Thymol, Kaempferol, Aloperine, Abietic acid (AA), Isogarcinol, Luteolin reduced the frequency and function of Th17 cells and simultaneously increased that of Treg cells. It is expected that our work can provide a reference for clinicians in drug use.

Dietary proanthocyanidins on gastrointestinal health and the interactions with gut microbiota

Many epidemiological and experimental studies have consistently reported the beneficial effects of dietary proanthocyanidins (PAC) on improving gastrointestinal physiological functions. This review aims to present a comprehensive perspective by focusing on structural properties, interactions and gastrointestinal protection of PAC. In brief, the main findings of this review are summarized as follows: (1) Structural features are critical factors in determining the bioavailability and subsequent pharmacology of PAC; (2) PAC and/or their bacterial metabolites can play a direct role in the gastrointestinal tract through their antioxidant, antibacterial, anti-inflammatory, and anti-proliferative properties; (3) PAC can reduce the digestion, absorption, and bioavailability of carbohydrates, proteins, and lipids by interacting with them or their according enzymes and transporters in the gastrointestinal tract; (4). PAC showed a prebiotic-like effect by interacting with the microflora in the intestinal tract, and the enhancement of PAC on a variety of probiotics, such as Bifidobacterium spp. and Lactobacillus spp. could be associated with potential benefits to human health. In conclusion, the potential effects of PAC in prevention and alleviation of gastrointestinal diseases are remarkable but clinical evidence is urgently needed.

Polyphenols affect the humoral response in cancer, infectious and allergic diseases and autoimmunity by modulating the activity of TH1 and TH2 cells

Polyphenols are a wide class of natural substances, pleiotropic molecules capable of modulating several processes, involved in the humoral and cellular immune response. The activation, differentiation of B cells, and production of antibodies to protein antigens by plasma cells depend on T helper (T_H) CD4⁺ cells and secreted cytokines. Cancer, infectious, allergic, and autoimmune diseases are characterized by an imbalance of T_H1/T_H2 immunity and abnormal activation of the humoral response. Accordingly, polyphenols modulate the T_H1/T_H2 ratio, the secretion of multiple cytokines, the levels of antibodies, and therefore could contribute to recovering the state of health in these diseases. In this review, we summarize the current knowledge on the effects of polyphenols in modulating the humoral response in cancer, infectious and allergic diseases and in autoimmunity by affecting the activity of T_H1 and T_H2 cells.

Immunomodulatory Effects of Dietary Polyphenols

Functional and nutraceutical foods provide an alternative way to improve immune function to aid in the management of various diseases. Traditionally, many medicinal products have been derived from natural compounds with healing properties. With the development of research into nutraceuticals, it is becoming apparent that many of the beneficial properties of these compounds are at least partly due to the presence of polyphenols. There is evidence that dietary polyphenols can influence dendritic cells, have an immunomodulatory effect on macrophages, increase proliferation of B cells, T cells and suppress Type 1 T helper (Th1), Th2, Th17 and Th9 cells. Polyphenols reduce inflammation by suppressing the pro-inflammatory cytokines in inflammatory bowel disease by inducing Treg cells in the intestine, inhibition of tumor necrosis factor-alpha (TNF-α) and induction of apoptosis, decreasing DNA damage. Polyphenols have a potential role in prevention/treatment of auto-immune diseases like type 1 diabetes, rheumatoid arthritis and multiple sclerosis by regulating signaling pathways, suppressing inflammation and limiting demyelination. In addition, polyphenols cause immunomodulatory effects against allergic reaction and autoimmune disease by inhibition of autoimmune T cell proliferation and downregulation of pro-inflammatory cytokines (interleukin-6 (IL-6), IL-1, interferon-γ (IFN-γ)). Herein, we summarize the immunomodulatory effects of polyphenols and the underlying mechanisms involved in the stimulation of immune responses.

Regulation of Enteric Infection and Immunity by Dietary Proanthocyanidins

The role of dietary components in immune function has acquired considerable attention in recent years. An important focus area is to unravel the role of bioactive dietary compounds in relation to enteric disease and their impact on gut mucosal immunity. Proanthocyanidins (PAC) are among the most common and most consumed dietary polyphenols, and are characterised by their variable molecular structures and diverse bioactivities. In particular, their anti-oxidative effects and ability to modulate gut microbiota have been widely described. However, there is limited evidence on the mechanism of action of PAC on the immune system, nor is it clearly established how PAC may influence susceptibility to enteric infections. Establishing the sites of action of PAC and their metabolites within the gut environment is fundamental to determine the applicability of PAC against enteric pathogens. Some mechanistic studies have shown that PAC have direct modulatory effects on immune cell signalling, isolated pathogens, and gut mucosal barrier integrity. Boosting the recruitment of immune cells and suppressing the amount of pro-inflammatory cytokines are modulating factors regulated by PAC, and can either be beneficial or detrimental in the course of re-establishing gut homeostasis. Herein, we review how PAC may alter distinct immune responses towards enteric bacterial, viral and parasitic infections, and how the modulation of gut microbiota may act as a mediating factor. Furthermore, we discuss how future studies could help unravel the role of PAC in preventing and/or alleviating intestinal inflammation and dysbiosis caused by enteric disease.

Myxopyrum serratulum ameliorates airway inflammation in LPS-stimulated RAW 264.7 macrophages and OVA-induced murine model of allergic asthma

ETHNOPHARMACOLOGICAL RELEVANCE

Myxopyrum serratulum A. W. Hill. (Oleaceae) is a traditionally used Indian medicinal plant for the treatment of cough, asthma and many other inflammatory diseases.

AIM OF THE STUDY

In this study, the protective effects of M. serratulum on airway inflammation was investigated in ovalbumin (OVA)-induced murine model of allergic asthma and lipopolysaccharide (LPS)-stimulated inflammation in RAW 264.7 murine macrophages, and the possible mechanisms were elucidated.

MATERIALS AND METHODS

The phytochemicals present in the methanolic leaf extract of M. serratulum (MEMS) were identified by reverse phase high performance liquid chromatography (RP-HPLC) analysis. In vitro anti-inflammatory activity of MEMS were evaluated by estimating the levels of nitric oxide (NO), reactive oxygen species (ROS) and cytokines (IL-1α, IL-1β, IL-2, IL-4, IL-6, IL-10, IL-12, IL-17A, IFN-γ, TNF-α, G-CSF and GM-CSF) in LPS-stimulated RAW 264.7 macrophages. In vivo anti-asthmatic activity of MEMS was studied using OVA-induced murine model. Airway hyperresponsiveness (AHR), was measured; total and differential cell counts, eosinophil peroxidase (EPO), prostaglandin E2 (PGE2), NO, ROS, and cytokines (IL-4, IL-5 and IL-13), were estimated in bronchoalveolar lavage fluid (BALF). Serum total IgE level was measured; and the histopathological changes of lung tissues were observed. The expressions of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) in lung tissue homogenates were detected by Western blot.

RESULTS

The chromatographic analysis of MEMS identified the presence of gallic acid, protocatechuic acid, catechin, ellagic acid, rutin, p-coumaric acid, quercetin, naringenin and apigenin. MEMS (125 and 250 μg/mL) dose-dependently reduced the levels of NO, ROS and pro-inflammatory cytokines in LPS-stimulated RAW 264.7 macrophages. MEMS (200 and 400 mg/kg, p.o.) significantly (p < 0.05) alleviated AHR; number of inflammatory cells, EPO, PGE2, NO, ROS, and cytokines (IL-4, IL-5 and IL-13) in BALF; serum total IgE and the histopathological changes associated with lung inflammation. Western blot studies showed that MEMS substantially suppressed COX-2 and iNOS protein expressions in the lung tissues of OVA-sensitized/challenged mice.

CONCLUSIONS

The present study corroborates for the first time the ameliorative effects of MEMS on airway inflammation by reducing the levels of oxidative stress, pro-inflammatory cytokines and inhibiting COX-2, iNOS protein expressions, thereby validating the ethnopharmacological uses of M. serratulum.

GSPE alleviates renal fibrosis by inhibiting the activation of C3/ HMGB1/ TGF-β1 pathway

Grape seed proanthocyanidin extract (GSPE) has been reported to exhibit a variety of protective effects, such as antioxidant, anti-atherosclerosis and other pharmacological effects. As a member of the complement system, complement component 3 (C3) deposition in the glomerulus is recognized as an important causative mediator of various kidney diseases. In this study, we aimed to identify the effect of GSPE on C3 in the chronic kidney fibrosis and evaluate the possible mechanism. We observed that administration of GSPE relieves inflammation and chronic renal fibrosis in mouse models of UUO. GSPE inhibited C3 secreted by macrophages to relieve renal interstitial inflammation. In vitro, we found that C3 stimulated HMGB1 translocation form nucleus to cytoplasm and promote the expression of pro-inflammatory cytokines including TGF-β1 in primary renal tubular epithelial cells (PTEC), which could be inhibited by GSPE. Meanwhile, GSPE could also decreased HMGB1-induced EMT of PTEC through suppresses the HMGB1/TLR4/p65/TGF-β1 pathway. In addition, the myofibroblast activation was inhibited by GSPE via TGF-β1/Smad2/3 signaling pathways in normal rat kidney fibroblast (NRK-49F) cells. Overall, these observations provide that GSPE alleviates renal fibrosis by inhibiting the C3/HMGB1/TGF-β1 pathway and could thus lead to find the potential therapy for the suppression of renal fibrosis.

Implication of oxidative stress in the pathogenesis of systemic sclerosis via inflammation, autoimmunity and fibrosis

Systemic sclerosis is an autoimmune disorder characterized by inflammation and a progressive fibrosis affecting the skin and visceral organs. Over the last two decades, it became clear that oxidative stress plays a key role in its pathogenesis. In this review, we highlighted the role of ROS in the various pathological components of systemic sclerosis, namely the inflammatory, the autoimmune and the fibrotic processes. We also discussed how these pathological processes can induce ROS overproduction, thus maintaining a vicious circle. Finally, we summarized the therapeutic approaches targeting oxidative stress tested in systemic sclerosis, in cells, animal models and patients.

Alpha-mangostin: Anti-inflammatory and antioxidant effects on established collagen-induced arthritis in DBA/1J mice

Rheumatoid arthritis (RA) is an autoimmune disease that causes physical disability in people worldwide. Despite progress made in RA treatment in the past decade, new drugs with high efficacy but few long-term adverse effects are still needed. This study focused on evaluating the therapeutic potential of α-mangostin on established collagen-induced arthritis (CIA) in DBA/1J mice. Arthritic DBA/1J mice were orally administered with two doses of α-mangostin (10 and 40 mg/kg) daily, for 33 days. Alpha-mangostin significantly decreased the clinical score in the short term at both doses and decreased the histopathological score at the higher dose. This improvement was accompanied by a reduction on serum levels of anti-collagen IgG2a autoantibodies and of the production of LIX/CXCL5, IP-10/CXCL10, MIG/CXCL9, RANTES/CCL5, IL-6 and IL-33 in the joints of CIA mice. Alpha-mangostin also exhibited an anti-oxidant effect decreasing the NADPH oxidase activity and lipid peroxidation and preserving the levels of reduced glutathione in the arthritic joints. In vitro this xanthone demonstrated modulatory properties on LPS-activated dendritic cells, although in Th1 and Th17-polarized lymphocytes promotes a pro-apoptotic phenotype. Altogether this study illustrates the capacity of α-mangostin to ameliorate the early clinical and histological signs of established CIA by reducing the inflammatory and oxidative responses.

Proanthocyanidins: novel treatment for psoriasis that reduces oxidative stress and modulates Th17 and Treg cells

Psoriasis is a common, chronic, inflammatory skin disease that affects 2%-4% of the global population. Recent studies have shown that increased oxidative stress (OS) and T-cell abnormalities are central to the pathogenesis of this disease. The resulting reactive oxygen species (ROS) induces proliferation and differentiation of Th17/Th1/Th22 cells and inhibits the anti-inflammatory activities of regulatory T lymphocytes (Treg). Subsequent secretions of inflammatory cytokines, such as interleukin (IL)-17, IL-22, tumor necrosis factor alpha (TNF-α), and interferon-gamma (IFN-γ), and vascular endothelial growth factor (VEGF), stimulate keratinocyte proliferation and angiogenesis. Proanthocyanidins are a class of flavonoids from plants and fruits, and have various antioxidant, anti-inflammatory, and anti-angiogenic properties. Numerous reports have demonstrated therapeutic effects of proanthocyanidins for various diseases. Among clinical activities, proanthocyanidins suppress cell proliferation, prevent OS, and regulate Th17/Treg cells. Because the pathogenesis of psoriasis involves OS and T cells dysregulation, we reviewed the effects of proanthocyanidins on OS, Th17 and Treg cell activities, and keratinocyte proliferation and angiogenesis. Data from multiple previous studies warrant consideration of proanthocyanidins as a promising strategy for the treatment of psoriasis.

Grape seed proanthocyanidin extract ameliorates murine autoimmune arthritis through regulation of TLR4/MyD88/NF-κB signaling pathway

BACKGROUND/AIMS

Grape seed proanthocyanidin extract (GSPE) has been reported to have a beneficial effect on regulating inf lammation. However, the anti-inflammatory mechanism of GSPE remains unclear. The aim of this study was to verify the influence of GSPE on the Toll-like receptor 4 (TLR4)-mediated signaling pathway in the regulation of murine autoimmune arthritis.

METHODS

Collagen-induced arthritis (CIA) was induced in dilute brown non-agouti (DBA)/1J mice. The mice were treated with GSPE (0 or 100 mg/kg) intraperitoneally. The severity of arthritis was assessed clinically, biochemically, and histologically. Immunostaining for TLR4 was performed. The expressions of TLR4 and downstream signaling molecules were analyzed by Western blot. The effect of GSPE on lipopolysaccharide (LPS)-induced TLR4 activation was also evaluated using RAW264.7 cells and fibroblast-like synoviocytes (FLSs) from patients with rheumatoid arthritis and from those with osteoarthritis.

RESULTS

GSPE attenuated the clinical severity of arthritis and decreased histological damage. GSPE treatment reduced the number of TLR4-stained cells in the synovium of mice with CIA. GSPE also downregulated the expression of TLR4, myeloid differentiation factor 88 (MyD88) and phosphorylated IκBα synovial protein in CIA mice. Concurrently, GSPE inhibited the nuclear translocation of nuclear factor-κB (NF-κB) subunits (p65 and p50). LPS-induced TLR4 activation was suppressed by GSPE in human FLS as well as in murine macrophages in vitro.

CONCLUSIONS

Our results demonstrated that GSPE ameliorated CIA by regulating the TLR4-MyD88-NF-κB signaling pathway.

The Role of Flavonoids in Inhibiting Th17 Responses in Inflammatory Arthritis

Flavonoids have been considered powerful anti-inflammatory agents, and their exact immunomodulatory action as therapeutic agents in autoimmune diseases has started to emerge. Their role in the manipulation of immunoregulation is less understood. Several studies attempted to investigate the role of various flavonoids mainly in experimental models of autoimmune diseases, especially in the context of their potential effect on the increase of regulatory T cells (Tregs) and their ability to stimulate an overexpression of anti-inflammatory cytokines, in particular that of IL-10. The emergence of IL-17, a cytokine largely produced by Th17 cells, as a powerful proinflammatory stimulus which attenuates the induction of Tregs has prompted a series of studies investigating the role of flavonoids on Th17 cells in experimental models as well as human autoimmune diseases. This review thoroughly discusses accumulated data on the role of flavonoids on Th17 in rheumatoid arthritis and experimental autoimmune arthritis.

A polyphenol-enriched diet and Ascaris suum infection modulate mucosal immune responses and gut microbiota composition in pigs

Polyphenols are a class of bioactive plant secondary metabolites that are thought to have beneficial effects on gut health, such as modulation of mucosal immune and inflammatory responses and regulation of parasite burdens. Here, we examined the interactions between a polyphenol-rich diet supplement and infection with the enteric nematode Ascaris suum in pigs. Pigs were fed either a basal diet or the same diet supplemented with grape pomace (GP), an industrial by-product rich in polyphenols such as oligomeric proanthocyanidins. Half of the animals in each group were then inoculated with A. suum for 14 days to assess parasite establishment, acquisition of local and systemic immune responses and effects on the gut microbiome. Despite in vitro anthelmintic activity of GP-extracts, numbers of parasite larvae in the intestine were not altered by GP-supplementation. However, the bioactive diet significantly increased numbers of eosinophils induced by A. suum infection in the duodenum, jejunum and ileum, and modulated gene expression in the jejunal mucosa of infected pigs. Both GP-supplementation and A. suum infection induced significant and apparently similar changes in the composition of the prokaryotic gut microbiota, and both also decreased concentrations of isobutyric and isovaleric acid (branched-chain short chain fatty acids) in the colon. Our results demonstrate that while a polyphenol-enriched diet in pigs may not directly influence A. suum establishment, it significantly modulates the subsequent host response to helminth infection. Our results suggest an influence of diet on immune function which may potentially be exploited to enhance immunity to helminths.

Oligomeric proanthocyanidins attenuate airway inflammation in asthma by inhibiting dendritic cells maturation

To date, although a promising anti-inflammatory activity of oligomeric proanthocyanidins (OPCs) has been observed in asthma, the mechanism responsible for these immunomodulatory properties remains obscure. Dendritic cells (DCs) that reside in the airway have been widely perceived as an important contributor to asthma. Our study was to demonstrate OPCs' effects on maturation and immunoregulation of pulmonary CD11c⁺ dendritic cells (DCs). BALB/c mice were exposed to ovalbumin (OVA) to induce murine model of asthma. In addition, pulmonary DCs and bone marrow-derived DCs (BMDCs) cultures were used to evaluate impacts of OPCs on DCs function. The results obtained here indicated that OPCs treatment dramatically reduced airway inflammation, such as the infiltration of inflammatory cells and the levels of allergen-specific serum IgE and Th2 cytokines. The expression of co-stimulatory molecules especially CD86 distributed on pulmonary DCs and bone marrow-derived DCs (BMDCs) also markedly declined. The phosphorylation of cAMP responsive element-binding protein (CREB) was significantly inhibited while no changes were observed in the expression of cAMP responsive element modulator (CREM). By transferring BMDCs into the airways of naïve mice, we found that OPCs-treated DCs (DC+OVA+OPC) were much less potent in promoting CD4⁺ T cells proliferation than OVA-pulsed DCs (DC+OVA), followed by the ameliorated eosinophilic inflammation in airway. Our findings tailor a novel profile of OPCs in the regulation of DCs function, shedding new light on the therapeutic potential of OPCs in asthma management.

Modulation of Inflammatory Response to Implanted Biomaterials Using Natural Compounds

Tissue engineering offers a promising strategy to restore injuries resulting from trauma, infection, tumor resection, or other diseases. In spite of significant progress, the field faces a significant bottleneck; the critical need to understand and exploit the interdependencies of tissue healing, angiogenesis, and inflammation. Inherently, the balance of these interacting processes is affected by a number of injury site conditions that represent a departure from physiological environment, including reduced pH, increased concentration of free radicals, hypoglycemia, and hypoxia. Efforts to harness the potential of immune response as a therapeutic strategy to promote tissue repair have led to identification of natural compounds with significant anti-inflammatory properties. This article provides a concise review of the body's inflammatory response to biomaterials and describes the role of oxygen as a physiological cue in this process. We proceed to highlight the potential of natural compounds to mediate inflammatory response and improve host-graft integration. Herein, we discuss the use of natural compounds to map signaling molecules and checkpoints that regulate the cross-linkage of immune response and skeletal repair.

Proanthocyanidins from the bark of Metasequoia glyptostroboides ameliorate allergic contact dermatitis through directly inhibiting T cells activation and Th1/Th17 responses

OBJECTIVE

The leaves and bark of Metasequoia glyptostroboides are used as anti-microbic, analgesic and anti-inflammatory drug for dermatic diseases in Chinese folk medicine. However, the pharmacological effects and material basis responsible for the therapeutic use of this herb have not yet been well studied. The objectives of this study were to evaluate the anti-inflammatory effects of the proanthocyanidin fraction from the bark of M. glyptostroboides (MGEB) and to elucidate its immunological mechanisms.

MATERIALS AND METHODS

The anti-inflammatory activity of MGEB was evaluated using 2,4-dinitrofluorobenzene (DNFB)-induced allergic contact dermatitis (ACD) in mice. Its potential mechanisms were further investigated by determining its effects on Con A-induced T cell activation and Th1/Th17 responses in vitro.

RESULTS

Both intraperitoneal injection and oral administration of MGEB significantly reduced the ear swelling in DNFB-induced ACD mice. MGEB inhibited Con A-induced proliferation and the expression levels of cell surface molecules CD69 and CD25 of T cells in vitro. MGEB also significantly decreased the production of Th1/Th17 specific cytokines (IL-2, IFN-γ and IL-17) and down-regulated their mRNA expression levels in activated T-cells.

CONCLUSIONS

MGEB could ameliorate ACD, at least in part, through directly inhibiting T cells activation and Th1/Th17 responses.

Celastrol, a Chinese herbal compound, controls autoimmune inflammation by altering the balance of pathogenic and regulatory T cells in the target organ

Inflammation is an integral component of autoimmune arthritis. The balance of pathogenic T helper 17 (Th17) and protective T regulatory (Treg) cells can influence disease severity, and its resetting offers an attractive approach to control autoimmunity. We determined the frequency of Th17 and Treg in the joints of rats with adjuvant arthritis (AA), a model of rheumatoid arthritis (RA). We also investigated the impact of Celastrol, a bioactive compound from the traditional Chinese medicine Celastrus that can suppress AA, on Th17/Treg balance in the joints. Celastrol treatment reduced Th17 cells but increased Treg in the joints, and it inhibited Th17 differentiation but promoted Treg differentiation in vitro by blocking the activation of pSTAT3. Furthermore, Celastrol limited the production of Th17-differentiating cytokines and chemokines (CCL3, CCL5). Thus, Celastrol suppressed arthritis in part by altering Th17/Treg ratio in inflamed joints, and it should be tested as a potential adjunct/alternative for RA therapy.

Sinomenine suppresses collagen-induced arthritis by reciprocal modulation of regulatory T cells and Th17 cells in gut-associated lymphoid tissues

Sinomenine (SIN) has long been used as a therapeutic agent of rheumatoid arthritis (RA) in China. However, the discrepancy between low oral bioavailability and higher minimal effective concentration made its action mode mysterious. The present study aimed to gain insight into the mechanisms by which SIN suppressed collagen-induced arthritis (CIA) in rats in view of Th17 and regulatory T (Treg) cell balance. SIN was orally administered, and the clinical symptoms of CIA rats were monitored; inflammatory cytokines levels in serum were measured by ELISA; pharmacokinetic studies were performed in normal and CIA rats; Th17 and Treg cell frequencies were analyzed by flow cytometry. The data showed that SIN treatment resulted in a dramatic decrease of arthritis scores and paw volume of CIA rats, which was accompanied by down-regulation of IL-17A and up-regulation of IL-10 in rat serum. The frequency of Treg cells was increased and the frequency of Th17 cells was decreased in the gut lymphoid tissues of SIN-treated rats. Immunohistochemistry assay demonstrated that more α4β7-positive cells were detained in joint tissues after SIN treatment. Moreover, the anti-arthritis efficacy of SIN disappeared when it was given by intraperitoneal injection, further confirming the action of SIN was gut-dependent. In conclusion, SIN exerts anti-RA action probably through modulating the frequencies of Treg cells and Th17 cells in intestinal lymph nodes and yielding a trafficking of lymphocytes (especially Treg cells) from gut to joint.

Norisoboldine ameliorates collagen-induced arthritis through regulating the balance between Th17 and regulatory T cells in gut-associated lymphoid tissues

Norisoboldine (NOR), the main active ingredient of the dry root of Lindera aggregata, was previously proven to have substantial therapeutic effects on collagen-induced arthritis (CIA) in mice by oral administration. However, it exhibited a very poor bioavailability in normal rats. The pharmacokinetic-pharmacodynamics disconnection attracts us to explore its anti-arthritic mechanism in more detail. In this study, NOR, administered orally, markedly attenuated the pathological changes in CIA rats, which was accompanied by the down-regulation of pro-inflammatory cytokines and the up-regulation of anti-inflammatory cytokine IL-10. Pharmacokinetic studies demonstrated that the plasma concentration of NOR was moderately elevated in CIA rats compared with normal rats, but it was still far lower than the minimal effective concentration required for inhibiting the proliferation and activation of T lymphocytes in vitro. Interestingly, NOR was shown to regulate the balance between Th17 and regulatory T (Treg) cells in the intestinal lymph nodes more strikingly than in other tissues. It could increase the expression of Foxp3 mRNA in both gut and joints, and markedly up-regulate the number of integrin α4β7 (a marker of gut source)-positive Foxp3(+) cells in the joints of CIA rats. These results suggest that the gut might be the primary action site of NOR, and NOR exerts anti-arthritis effect through regulating the balance between Th17 and Treg cells in intestinal lymph nodes and yielding a trafficking of lymphocytes (especially Treg cells) from the gut to joint. The findings of the present study also provide a plausible explanation for the anti-arthritic effects of poorly absorbed compounds like NOR.

Rebamipide attenuates autoimmune arthritis severity in SKG mice via regulation of B cell and antibody production

Oxidative stress is involved in the pathophysiology of rheumatoid arthritis (RA). We investigated the therapeutic potential of rebamipide, a gastroprotective agent with a property of reactive oxygen species scavenger, on the development of inflammatory polyarthritis and the pathophysiological mechanisms by which rebamipide might confer anti-arthritic effects in SKG mice, an animal model of RA. Intraperitoneal (i.p.) injection of rebamipide attenuated the severity of clinical and histological arthritis. Rebampide treatment reduced the number of T helper type 1 (Th1), Th2, Th17, inducible T cell co-stimulator (ICOS)(+) follicular helper T (Tfh) transitional type (T2) and mature B cells in the spleen, but increased the number of regulatory T (Treg ), CD19(+) CD1d(high) CD5(high) , CD19(+) CD25(high) forkhead box protein 3 (FoxP3)(+) regulatory B (Breg ) cells, memory B cells, and transitional type 1 (T1) B cells. In addition, flow cytometric analysis revealed significantly decreased populations of FAS(+) GL-7(+) germinal centre B cells and B220(-) CD138(+) plasma cells in the spleens of rebamipide-treated SKG mice compared to controls. Rebamipide decreased germinal centre B cells and reciprocally induced Breg cells in a dose-dependent manner in vitro. Rebamipide-induced Breg cells had more suppressive capacity in relation to T cell proliferation and also inhibited Th17 differentiation from murine CD4(+) T cells. Together, these data show that i.p. administration of rebamipide suppresses arthritis severity by inducing Breg and Treg cells and suppressing Tfh and Th17 cells in a murine model of RA.

Gene associated with retinoid-interferon-induced mortality 19 attenuates murine autoimmune arthritis by regulation of th17 and treg cells

OBJECTIVE

STAT-3 is a key transcriptional factor in the interleukin-6 (IL-6)-mediated differentiation of Th17 cells. Because Th17 is believed to be a central player in rheumatoid arthritis (RA), we sought to evaluate whether an endogenous inhibitor of the STAT3 gene, GRIM-19 (gene associated with retinoid-interferon-induced mortality 19), could attenuate the progression and severity of murine collagen-induced arthritis (CIA) through suppression of Th17 cells and, reciprocally, could increase expression of Treg cells.

METHODS

Overexpression of GRIM-19 was produced either by intravenous/intramuscular administration of a GRIM-19 overexpression vector in DBA1/J mice or by development of GRIM-19-transgenic (Tg) mice on a C57BL/6 background. Clinical signs were scored for arthritis severity, and mouse splenocytes, serum, and joint tissue were obtained for immunostaining and histologic analyses.

RESULTS

The numbers of CD4+IL-17+ cells and CD4+pSTAT3+ cells were decreased, while the numbers of CD4+CD25+Foxp3+ cells and CD4+pSTAT5+ cells were increased, in both GRIM-19 vector-transfected and GRIM-19-Tg mice. Administration of the GRIM-19 overexpression vector into mice with CIA markedly suppressed the clinical and histologic signs of arthritis in the affected joints. Similarly, when CIA was induced in GRIM-19-Tg mice, the arthritis phenotype was markedly attenuated and the expression of inflammatory cytokines (IL-1β, IL-6, tumor necrosis factor α, and IL-17) in the arthritic joints was also significantly reduced. Moreover, bone marrow-derived monocyte/macrophages obtained from GRIM-19-Tg mice showed attenuated RANKL-induced osteoclastogenesis in vitro.

CONCLUSION

GRIM-19 improved the clinical and histologic features of CIA and also inhibited osteoclast formation. These findings suggest that GRIM-19 may be a novel treatment agent for RA.

T regulatory cells in childhood arthritis--novel insights

In recent years, there have been many new developments in the field of regulatory T cells (Treg), challenging the consensus on their behaviour, classification and role(s) in disease. The role Treg might play in autoimmune disease appears to be more complex than previously thought. Here, we discuss the current knowledge of regulatory T cells through animal and human research and illustrate the recent developments in childhood autoimmune arthritis (juvenile idiopathic arthritis (JIA)). Furthermore, this review summarises our understanding of the fields and assesses current and future implications for Treg in the treatment of JIA.

Grape seed proanthocyanidin extract-mediated regulation of STAT3 proteins contributes to Treg differentiation and attenuates inflammation in a murine model of obesity-associated arthritis

Grape seed proanthocyanidin extract (GSPE) is a natural flavonoid that exerts anti-inflammatory properties. Obesity is an inflammatory condition and inflammatory cells and their secretion of pro-inflammatory molecules contribute to the pathogenesis of obesity. Rheumatoid arthritis (RA) is a chronic autoimmune disease that is characterized by inflammation of joints lined by synovium. Previously, we demonstrated that obesity augmented arthritis severity in collagen induced arthritis (CIA), a murine model of human RA. Here, we investigated whether oral administration of GSPE showed antiobesity and anti-arthritic effects in high-fat diet-induced obese (DIO) mice and in obese CIA mice, respectively. The pathophysiologic mechanisms by which GSPE attenuates weight gain and arthritis severity in vivo were also investigated. In DIO mice, GSPE administration significantly inhibited weight gain, reduced fat infiltration in liver and improved serum lipid profiles. The antiobesity effect of GSPE was associated with increased populations of regulatory T (Treg) cells and those of decreased Th17 cells. Decrease of Th17 cells was associated with significant inhibition of their key transcriptional factors, pSTAT3(Tyr705) and pSTAT3(Ser727). On the contrary, GSPE-induced Treg induction was associated with enhanced pSTAT5 expression. To identify the anti-arthritis effects of GSPE, GSPE was given orally for 7 weeks after type II collagen immunization. GSPE treatment significantly attenuated the development of autoimmune arthritis in obese CIA model. In line with DIO mice, GSPE administration decreased Th17 cells and reciprocally increased Treg cells by regulating STAT proteins in autoimmune arthritis model. The expressions of pro-inflammatory cytokines and nitrotyrosine in synovium were significantly inhibited by GSPE treatment. Taken together, GSPE functions as a reciprocal regulator of T cell differentiation - suppression of Th17 cells and induction of Tregs in both DIO and obese CIA mice. GSPE may act as a therapeutic agent to treat immunologic diseases related with enhanced STAT3 activity such as metabolic disorders and autoimmune diseases.

Therapeutic potential of interleukin-17 in inflammation and autoimmune diseases

INTRODUCTION

Interleukin-17 (IL-17) is a proinflammatory cytokine that mainly produced by T helper 17 (Th17) cells. In this article, we discussed the role of IL-17 in inflammation and autoimmune diseases, and the therapeutic strategies targeting IL-17.

AREAS COVERED

In this article, we discussed the proinflammatory cytokine IL-17 and IL-17 receptors signals, and their regulation. IL-17 expression was abnormal in the bacterium, virus and fungus infection, and its higher level caused the tissue inflammation. IL-17 was involved in the pathological process of autoimmune diseases, such as systemic sclerosis, rheumatoid arthritis, ankylosing spondylitis and systemic lupus erythematosus, and IL-17 has been put as a therapeutic target in the clinic.

EXPERT OPINION

IL-17/IL-17R signals and their application in inflammation process still need to be explored. Therapeutic strategies targeting IL-17 in autoimmune diseases ameliorated the inadequate response to anti-TNF-α therapy.

In vivo action of IL-27: reciprocal regulation of Th17 and Treg cells in collagen-induced arthritis

Interleukin (IL)-27 is a novel cytokine of the IL-6/IL-12 family that has been reported to be involved in the pathogenesis of autoimmune diseases and has a pivotal role as both a pro- and anti-inflammatory cytokine. We investigated the in vivo effects of IL-27 on arthritis severity in a murine collagen-induced arthritis (CIA) model and its mechanism of action regarding control of regulatory T (Tregs) and IL-17-producing T helper 17 (Th17) cells. IL-27-Fc-treated CIA mice showed a lower severity of arthritis. IL-17 expression in the spleens was significantly decreased in IL-27-Fc-treated CIA mice compared with that in the CIA model. The Th17 population was decreased in the spleens of IL-27-Fc-treated CIA mice, whereas the CD4⁺CD25⁺Foxp3⁺ Treg population increased. In vitro studies revealed that IL-27 inhibited IL-17 production in murine CD4⁺ T cells, and the effect was associated with retinoic acid-related orphan receptor γT and signal transducer and activator of transcription 3 inhibition. In contrast, fluorescein isothiocyanate-labeled forkhead box P3 (Foxp3) and IL-10 were profoundly augmented by IL-27 treatment. Regarding the suppressive capacity of Treg cells, the proportions of CTLA-4⁺ (cytotoxic T-lymphocyte antigen 4), PD-1⁺ (programmed cell death protein 1) and GITR⁺ (glucocorticoid-induced tumor necrosis factor receptor) Tregs increased in the spleens of IL-27-Fc-treated CIA mice. Furthermore, in vitro differentiated Treg cells with IL-27 exerted a more suppressive capacity on T-cell proliferation. We found that IL-27 acts as a reciprocal regulator of the Th17 and Treg populations in CD4⁺ cells isolated from healthy human peripheral blood mononuclear cells (PBMCs), as well as from humans with rheumatoid arthritis (RA) PBMCs. Our study suggests that IL-27 has the potential to ameliorate overwhelming inflammation in patients with RA through a reciprocal regulation of Th17 and Treg cells.

Prevention of colitis-associated cancer: natural compounds that target the IL-6 soluble receptor

The risk of developing colorectal cancer increases in patients with inflammatory bowel disease (IBD) and a growing body of evidence shows the critical role of interleukin (IL-6) in this process. IL-6 is both a pro- and anti-inflammatory cytokine whose effects are mediated through activation of STAT3. Recent studies have also demonstrated that IL-6 trans-signaling through its soluble receptor occurs in IBD and cancer. IL-6 trans-signaling therefore is emerging as an attractive approach to diminish the inflammatory signals in conditions of chronic inflammation. The purpose of cancer chemoprevention is to either delay the onset or progression from precancerous lesions. Natural compounds because of their low toxicity render themselves excellent candidates that can be administered over the lifetime of an individual. With the focus of managing IBD over a long time and preventing onset of colitis-associated cancer, we believe that there should be increased research focus on identifying chemopreventive compounds that can render themselves to long term use possibly for the lifetime of predisposed individuals. Here, we review the role of IL-6 signaling in IBD and colitis-associated cancer and underscore the importance of searching for natural compounds that would target the IL-6 trans-signaling pathway as a way to diminish chronic inflammatory conditions in the gastrointestinal tract and possibly hamper the progression to colon cancer. We propose that effective screening and identification of natural chemopreventive compounds that target IL-6 trans-signaling has important implications for the development of optimal strategies against cancer development triggered by inflammation.

p53 controls autoimmune arthritis via STAT-mediated regulation of the Th17 cell/Treg cell balance in mice

OBJECTIVE

To investigate the connection between p53 and interleukin-17-producing Th17 cell/Treg cell balance in rheumatoid arthritis (RA).

METHODS

Th17 cell and Treg cell frequencies were analyzed by flow cytometry, and cytokine levels in the supernatant were determined using enzyme-linked immunosorbent assays. The expression of transcription factors was analyzed by immunostaining and Western blotting, and the interactions between p53 and STAT-3 or STAT-5 were determined by immunoprecipitation-Western blot analysis. A p53 agonist was administered in the collagen-induced arthritis (CIA) model, and the effects in vivo were determined.

RESULTS

CD4+ T cells from p53-/- mice decreased the activity of STAT-5, lowered the level of phosphorylated STAT-5, and compromised Treg cell differentiation. The protein p53 bound STAT-5 directly, and this interaction was enhanced with increasing p53 activity. Under inflammatory conditions, p53 suppressed Th17 cell differentiation and skewed T cells toward Treg cell differentiation through the activation of STAT-5 signaling cascades. In mice with CIA, injection of a p53 overexpression vector or an antagonist of Mdm2 had the effect of controlling arthritis development in vivo. The regulatory effect of p53 was recapitulated in the cells of RA patients, with more pronounced suppression due to the repressed status of p53 in RA.

CONCLUSION

We demonstrated a link between p53-mediated and STAT-mediated regulation of Th17 cells/Treg cells in RA. Our results suggest that factors involved in this pathway might constitute novel therapeutic targets for the treatment of RA.

Redox regulation of T-cell function: from molecular mechanisms to significance in human health and disease

Reactive oxygen species (ROS) are thought to have effects on T-cell function and proliferation. Low concentrations of ROS in T cells are a prerequisite for cell survival, and increased ROS accumulation can lead to apoptosis/necrosis. The cellular redox state of a T cell can also affect T-cell receptor signaling, skewing the immune response. Various T-cell subsets have different redox statuses, and this differential ROS susceptibility could modulate the outcome of an immune response in various disease states. Recent advances in T-cell redox signaling reveal that ROS modulate signaling cascades such as the mitogen-activated protein kinase, phosphoinositide 3-kinase (PI3K)/AKT, and JAK/STAT pathways. Also, tumor microenvironments, chronic T-cell stimulation leading to replicative senescence, gender, and age affect T-cell susceptibility to ROS, thereby contributing to diverse immune outcomes. Antioxidants such as glutathione, thioredoxin, superoxide dismutase, and catalase balance cellular oxidative stress. T-cell redox states are also regulated by expression of various vitamins and dietary compounds. Changes in T-cell redox regulation may affect the pathogenesis of various human diseases. Many strategies to control oxidative stress have been employed for various diseases, including the use of active antioxidants from dietary products and pharmacologic or genetic engineering of antioxidant genes in T cells. Here, we discuss the existence of a complex web of molecules/factors that exogenously or endogenously affect oxidants, and we relate these molecules to potential therapeutics.

Mediators of inflammation-induced bone damage in arthritis and their control by herbal products

Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic inflammation of the synovial joints leading to bone and cartilage damage. Untreated inflammatory arthritis can result in severe deformities and disability. The use of anti-inflammatory agents and biologics has been the mainstay of treatment of RA. However, the prolonged use of such agents may lead to severe adverse reactions. In addition, many of these drugs are quite expensive. These limitations have necessitated the search for newer therapeutic agents for RA. Natural plant products offer a promising resource for potential antiarthritic agents. We describe here the cellular and soluble mediators of inflammation-induced bone damage (osteoimmunology) in arthritis. We also elaborate upon various herbal products that possess antiarthritic activity, particularly mentioning the specific target molecules. As the use of natural product supplements by RA patients is increasing, this paper presents timely and useful information about the mechanism of action of promising herbal products that can inhibit the progression of inflammation and bone damage in the course of arthritis.

Cranberry proanthocyanidins improve intestinal sIgA during elemental enteral nutrition

BACKGROUND

Elemental enteral nutrition (EEN) decreases gut-associated lymphoid tissue (GALT) function, including fewer Peyer's patch lymphocytes and lower levels of the tissue T helper 2 (Th2) cytokines and mucosal transport protein polymeric immunoglobulin receptor (pIgR), leading to lower luminal secretory immunoglobulin A (sIgA) levels. Since we recently demonstrated that cranberry proanthocyanidins (PACs) maintain the Th2 cytokine interleukin (IL)-4 when added to EEN, we hypothesized the addition of PACs to EEN would normalize other GALT parameters and maintain luminal levels of sIgA.

METHODS

Institute of Cancer Research mice were randomized (12/group) to receive chow, EEN, or EEN + PACs (100 mg/kg body weight) for 5 days, starting 2 days after intragastric cannulation. Ileum tissue was collected to measure IL-4 by enzyme-linked immunosorbent assay, pIgR by Western blot, and phosphorylated STAT-6 by microarray. Intestinal wash fluid was collected to measure sIgA by Western blot.

RESULTS

Compared with chow, EEN significantly decreased tissue IL-4, phosphorylated STAT-6, and pIgR. The addition of PACs to EEN prevented these alterations. Compared with chow, EEN resulted in significantly lower levels of luminal sIgA. The addition of PACs to EEN increased luminal sIgA levels compared with EEN alone.

CONCLUSIONS

This study suggests the addition of PACs to EEN may support GALT function and maintain intestinal sIgA levels compared with EEN administration alone.

Grape-seed proanthocyanidin extract as suppressors of bone destruction in inflammatory autoimmune arthritis

Chronic autoimmune inflammation, which is commonly observed in rheumatoid arthritis (RA), disrupts the delicate balance between bone resorption and formation causing thedestruction of the bone and joints. We undertook this study to verify the effects of natural grape-seed proanthocyanidin extract (GSPE), an antioxidant, on chronic inflammation and bone destruction. GSPE administration ameliorated the arthritic symptoms of collagen-induced arthritis (CIA), which are representative of cartilage and bone destruction. GSPE treatment reduced the formation of tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cells and osteoclast activity and increased differentiation of mature osteoblasts. Receptor activator of NFκB ligand expression in fibroblasts from RA patients was abrogated with GSPE treatment. GSPE blocked human peripheral blood mononuclear cell-derived osteoclastogenesis and acted as an antioxidant. GSPE improved the arthritic manifestations of CIA mice by simultaneously suppressing osteoclast differentiation and promoting osteoblast differentiation. Our results suggest that GSPE may be beneficial for the treatment of inflammation-associated bone destruction.

Key molecules in the differentiation and commitment program of T helper 17 (Th17) cells up-to-date

The mechanisms underlying autoimmunity and cancer remain elusive. However, perpendicular evidence has been evolved in the past decade that T helper (Th)17 cells and their related molecules are implicated in initiation and induction of various disease settings including both diseases. Meanwhile, extensive research on Th17 cells elucidated various molecules including cytokines and transcription factors as well as signaling pathways involved in the differentiation, maturation, survival and ultimate commitment of Th17 cells. In the current review, we revise the mechanistic underpinnings delivered by recent research on these molecules in the Th17 differentiation/commitment concert. We emphasize on those molecules proposed as targets for attaining potential therapies of various autoimmune disorders and cancer, aiming both at dampening the dark-side of Th17 repertoire and simultaneously potentiating its benefits in the roster of the antimicrobial response.

TWEAK promotes the production of Interleukin-17 in rheumatoid arthritis

Tumor necrosis factor (TNF)-like weak inducer of apoptosis (TWEAK) is an inflammatory cytokine that modulates several biological responses by inducing chemokines and proinflammatory cytokines. We hypothesized that TWEAK could promote secretion of IL-17, an amplifier of inflammatory arthritis. To test this, we investigated the capacity of TWEAK to induce IL-17 production in T cells via the fibroblast growth factor-inducible gene 14 (Fn14, also known as TWEAK receptor) signal pathway in rheumatoid arthritis (RA). Fn14 and IL-17 were highly expressed in arthritic tissues of collagen-induced arthritis (CIA) mice. TWEAK induced production of IL-17 alone and synergistically with lipopolysaccharide. In naïve murine T cells, TWEAK promoted Th17 differentiation. The expression of Fn14 was predominant in Th17 cells. TWEAK and IL-17 concentrations were significantly higher in synovial fluid and serum in RA patients than OA patients. In addition, we identified CD4(+)IL-17(+)Fn14(+) cells in synovium from RA patients. TWEAK promoted IL-17 production synergistically with IL-23 or IL-21 and blockade of Fn14 with Fn14-Fc suppressed Th17 differentiation. Conversely, this treatment enhanced Treg differentiation. These results suggest that TWEAK induces IL-17 production and may be a therapeutic target in the treatment of RA.

Adoptive transfer of all-trans-retinal-induced regulatory T cells ameliorates experimental autoimmune arthritis in an interferon-gamma knockout model

Maintaining an appropriate balance between subsets of CD4(+) helper T cells and T regulatory cells (Tregs) is a critical process in immune homeostasis and a protective mechanism against autoimmunity and inflammation. To identify the role of vitamin A-related compounds, we investigated the regulation of interleukin (IL)-17-producing helper T cells (Th17 cells) and Tregs treated with all-trans-retinal (retinal). CD4(+)T cells or total cells from the spleens of C57BL/6 mice were stimulated under Treg-polarizing (anti-CD3/CD28 and TGF-β) or Th17-polarizing (anti-CD3/CD28, TGF-β, and IL-6) conditions in the presence or absence of retinal. To analyze their suppressive abilities, retinal-induced Tregs or TGF-β-induced Tregs were co-cultured with responder T cells. Collagen-induced arthritis (CIA) was established in interferon (IFN)-γ knockout mice. On day 13, retinal-induced Tregs were adoptively transferred to mice with established CIA after second immunizations. Compared with TGF-β-induced Treg cells, retinal-induced Tregs showed increased Foxp3 expression and mediated stronger suppressive activity. Under Th17-polarizing conditions, retinal inhibited the production of IL-17 and increased the expression of Foxp3.Retinal-induced Tregs showed therapeutic effects in IFN-γ knockout CIA mice. Thus, we demonstrated that retinal reciprocally regulates Foxp3(+) Tregs and Th17 cells. These findings suggest that retinal, a vitamin A metabolite, can regulate the balance between pro- and anti-inflammatory immunity. A better understanding of the manipulation of Foxp3 and Tregs may enable the application of this tremendous therapeutic potential in various autoimmune diseases.

Dietary agents in cancer prevention: an immunological perspective

Skin cancer is the most common form of cancer diagnosed in the United States. Exposure to solar ultraviolet (UV) radiations is believed to be the primary cause for skin cancer. Excessive UV radiation can lead to genetic mutations and damage in the skin's cellular DNA that in turn can lead to skin cancer. Lately, chemoprevention by administering naturally occurring non-toxic dietary compounds has proven to be a potential strategy to prevent the occurrence of tumors. Attention has been drawn toward several natural dietary agents such as resveratrol, one of the major components found in grapes, red wines, berries and peanuts, proanthocyanidins from grape seeds, (-)-epigallocatechin-3-gallate from green tea, etc. However, the effect these dietary agents have on the immune system and the immunological mechanisms involved therein are still being explored. In this review, we shall focus on the role of key chemopreventive agents on various immune cells and discuss their potential as antitumor agents with an immunological perspective.

Dietary flavonoid naringenin induces regulatory T cells via an aryl hydrocarbon receptor mediated pathway

The aryl hydrocarbon receptor (AhR), a transcription factor mediating xenobiotic detoxification, plays a considerable role in regulatory T cell (Treg) induction. Tregs regulate the immune system, thus suppressing allergies and autoimmune diseases. This study aims to identify new types of antiallergic dietary factors, with focus on the flavonoids with potential AhR agonistic activity. Among 25 dietary flavonoid samples tested using a reporter assay, 8 showed marked induction of AhR-dependent transcriptional activity. The subsequent T cell proliferation suppression assay identified naringenin as the only sample capable of stimulating Treg induction; notably, this induction was eliminated by cotreatment with AhR antagonists. Indeed, naringenin induced CD4(+)Foxp3(+) Tregs, irrespective of the presence of the transforming growth factor-β (TGF-β), indicating that the conventional TGF-β-dependent signaling pathway might not be involved.

Rheumatoid arthritis and periodontitis - inflammatory and infectious connections. Review of the literature

An association between oral disease/periodontitis and rheumatoid arthritis (RA) has been considered since the early 1820s. The early treatment was tooth eradication. Epidemiological studies suggest that the prevalence of RA and periodontitis may be similar and about 5% of the population are aged 50 years or older. RA is considered as an autoimmune disease whereas periodontitis has an infectious etiology with a complex inflammatory response. Both diseases are chronic and may present with bursts of disease activity. Association studies have suggested odds ratios of having RA and periodontitis varying from 1.8:1 (95% CI: 1.0–3.2, NS) to 8:1 (95% CI: 2.9–22.1, p<0.001). Genetic factors are driving the host responses in both RA and periodontitis. Tumor necrosis factor-α, a proinflammatory cytokine, regulates a cascade of inflammatory events in both RA and periodontitis. Porphyromonas gingivalis is a common pathogen in periodontal infection. P. gingivalis has also been identified in synovial fluid. The specific abilities of P. gingivalis to citrullinate host peptides by proteolytic cleavage at Arg-X peptide bonds by arginine gingipains can induce autoimmune responses in RA through development of anticyclic citrullinated peptide antibodies. In addition, P. gingivalis carries heat shock proteins (HSPs) that may also trigger autoimmune responses in subjects with RA. Data suggest that periodontal therapies combined with routine RA treatments further improve RA status.