Suppressive effects of fisetin on mice T lymphocytes in vitro and in vivo

Application potential of senolytics in clinical treatment

Of the factors studied in individual ageing, the accumulation of senescent cells has been considered as an essential cause of organ degeneration to eventually initiate age-related diseases. Cellular senescence is attributed to the accumulation of damage for an inducement in the activation of cell cycle inhibitory pathways, resulting the cell permanently withdraw from the cell proliferation cycle. Further, senescent cells will activate the inflammatory factor secretion pathway to promote the development of various age-related diseases. Senolytics, a small molecule compound, can delay disease development and extend mammalian lifespan. The evidence from multiple trials shows that the targeted killing of senescent cells has a significant clinical application for the treatment of age-related diseases. In addition, senolytics are also significant for the development of ageing research in solid organ transplantation, which can fully develop the potential of elderly organs and reduce the age gap between demand and supply. We conclude that the main characteristics of cellular senescence, the anti-ageing drug senolytics in the treatment of chronic diseases and organ transplantation, and the latest clinical progress of related researches in order to provide a theoretical basis for the prevention and treatment of ageing and related diseases.

Immunomodulating Phytochemicals: An Insight Into Their Potential Use in Cytokine Storm Situations

Phytochemicals are compounds found in plants that possess a variety of bioactive properties, including antioxidant and immunomodulatory properties. Recent studies have highlighted the potential of phytochemicals in targeting specific signalling pathways involved in cytokine storm, a life-threatening clinical condition resulting from excessive immune cell activation and oversupply of proinflammatory cytokines. Several studies have documented the immunomodulatory effects of phytochemicals on immune function, including their ability to regulate essential cellular and molecular interactions of immune system cells. This makes them a promising alternative for cytokine storm management, especially when combined with existing chemotherapies. Furthermore, phytochemicals have been found to target multiple signalling pathways, including the TNF-α/NF-κB, IL-1/NF-κB, IFN-γ/JAK/STAT, and IL-6/JAK-STAT. These pathways play critical roles in the development and progression of cytokine storm, and targeting them with phytochemicals represents a promising strategy for controlling cytokine release and the subsequent inflammation. Studies have also investigated certain families of plant-related constituents and their potential immunomodulatory actions. In vivo and in vitro studies have reported the immunomodulatory effects of phytochemicals, which provide viable alternatives in the management of cytokine storm syndrome. The collective data from previous studies suggest that phytochemicals represent a potentially functional source of cytokine storm treatment and promote further exploration of these compounds as immunomodulatory agents for suppressing specific signalling cascade responses. Overall, the previous research findings support the use of phytochemicals as a complementary approach in managing cytokine storm and improving patient outcomes.

Comprehensive and critical view on the anti-inflammatory and immunomodulatory role of natural phenolic antioxidants

The immune response encompasses innate and adaptive immunity, each with distinct and specific activities. The innate immune system is constituted by phagocytic cells, macrophages, monocytes and neutrophils, the cascade system, and different classes of receptors such as toll-like receptors that are exploited by the innate immune cells. The adaptive immune system is antigen-specific, encompassing memory lymphocytes and the corresponding specific receptors. Inflammation is understood as an activation of different signaling pathways such as toll-like receptors or nuclear factor kappa-light-chain-enhancer of activated B cells, with an increase in nitric oxide, inflammatory cytokines and chemokines. Increased oxidative stress has been identified as main source of chronic inflammation. Phenolic antioxidants modulate the activities of lymphocytes and macrophages by impacting cytokines and nitric oxide release, exerting anti-inflammatory effect. The nuclear-factor kappa-light-chain-enhancer of activated B cells signaling pathway and the mitogen-activated protein kinase pathway are targeted, alongside an increase in nuclear factor erythroid 2-related factor mediated antioxidant response, triggering the activity of antioxidant enzymes. The inhibitive potential on phospholipase A2, cyclooxygenase and lipoxygenase in the arachidonic acid pathway, and the subsequent reduction in prostaglandin and leukotriene generation, reveals the potential of phenolics as inflammation antagonists. The immunomodulative potential encompasses the capacity to interfere with proinflammatory cytokine synthesis and with the expression of the corresponding genes. A diet rich in antioxidants can result in prevention of inflammation-related pathologies. More investigations are necessary to establish the role of these antioxidants in therapy. The appropriate delivery system and the prooxidant effects exhibited at large doses, or in the presence of heavy metal cations should be regarded.

Impact of senolytic treatment on immunity, aging, and disease

Cellular senescence has been implicated in the pathophysiology of many age-related diseases. However, it also plays an important protective role in the context of tumor suppression and wound healing. Reducing senescence burden through treatment with senolytic drugs or the use of genetically targeted models of senescent cell elimination in animals has shown positive results in the context of mitigating disease and age-associated inflammation. Despite positive, albeit heterogenous, outcomes in clinical trials, very little is known about the short-term and long-term immunological consequences of using senolytics as a treatment for age-related conditions. Further, many studies examining cellular senescence and senolytic treatment have been demonstrated in non-infectious disease models. Several recent reports suggest that senescent cell elimination may have benefits in COVID-19 and influenza resolution and disease prognosis. In this review, we discuss the current clinical trials and pre-clinical studies that are exploring the impact of senolytics on cellular immunity. We propose that while eliminating senescent cells may have an acute beneficial impact on primary immune responses, immunological memory may be negatively impacted. Closer investigation of senolytics on immune function and memory generation would provide insight as to whether senolytics could be used to enhance the aging immune system and have potential to be used as therapeutics or prophylactics in populations that are severely and disproportionately affected by infections such as the elderly and immunocompromised.

Spice-Derived Phenolic Compounds: Potential for Skin Cancer Prevention and Therapy

Skin cancer is a condition characterized by the abnormal growth of skin cells, primarily caused by exposure to ultraviolet (UV) radiation from the sun or artificial sources like tanning beds. Different types of skin cancer include melanoma, basal cell carcinoma, and squamous cell carcinoma. Despite the advancements in targeted therapies, there is still a need for a safer, highly efficient approach to preventing and treating cutaneous malignancies. Spices have a rich history dating back thousands of years and are renowned for their ability to enhance the flavor, taste, and color of food. Derived from various plant parts like seeds, fruits, bark, roots, or flowers, spices are important culinary ingredients. However, their value extends beyond the culinary realm. Some spices contain bioactive compounds, including phenolic compounds, which are known for their significant biological effects. These compounds have attracted attention in scientific research due to their potential health benefits, including their possible role in disease prevention and treatment, such as cancer. This review focuses on examining the potential of spice-derived phenolic compounds as preventive or therapeutic agents for managing skin cancers. By compiling and analyzing the available knowledge, this review aims to provide insights that can guide future research in identifying new anticancer phytochemicals and uncovering additional mechanisms for combating skin cancer.

The influence of phytochemicals on cell heterogeneity in chronic inflammation-associated diseases: the prospects of single cell sequencing

Chronic inflammation-associated diseases include, but is not limited to cardiovascular disease, cancer, obesity, diabetes, etc. Cell heterogeneity is a prerequisite for understanding the physiological and pathological development of cell metabolism, and its response to external stimuli. Recently, dietary habits based on phytochemicals became increasingly recognized to play a pivotal role in chronic inflammation. Phytochemicals can relieve chronic inflammation by regulating inflammatory cell differentiation and immune cell response, but the influence of phytochemicals on cell heterogeneity from in vitro and ex vivo studies cannot simulate the complexity of cell differentiation in vivo due to the differences in cell lines and extracellular environment. Therefore, there is no consensus on the regulation mechanism of phytochemicals on chronic diseases based on cell heterogeneity. The purpose of this review is to summarize cell heterogeneity in common chronic inflammation-associated diseases and trace the effects of phytochemicals on cell differentiation in chronic diseases development. More importantly, by discussing the problems and challenges which hinder the study of cell heterogeneity in recent nutritional assessment experiments, we propose new prospects based on the drawbacks of existing research to optimize the research on the regulation mechanism of phytochemicals on chronic diseases. The need to explore precise measurements of cell heterogeneity is a key pillar in understanding the influence of phytochemicals on certain diseases. In the future, deeper understanding of cell-to-cell variation and the impact of food components and their metabolites on cell function by single-cell genomics and epigenomics with the focus on individual differences will open new avenues for the next generation of health care.

Effects of Fisetin on Allergic Contact Dermatitis via Regulating the Balance of Th17/Treg in Mice

Background. Allergic contact dermatitis (ACD) is a form of chronic cutaneous inflammatory disease of immunological origin that has adverse impacts on patient quality of life, underscoring the need for the development of safe and effective therapeutic agents to treat affected individuals. Fisetin is a Chinese herbal preparation that reportedly exhibits antitumor, antioxidant, antimicrobial, anticoagulatory, and antimalarial activity. In the current report, the immunomodulatory activity of fisetin was appraised by assessing its impact on balance between regulatory T (Treg) and Th17 cells in an ACD model. Methods. BALB/c mice ( $n=60$ ) were randomized into control, ACD model, CTX positive control (20 mg/kg), and fisetin treatment groups (three dose levels: 2, 4, or 8 mg/kg). ACD induction was achieved by sensitizing mice on the shaved ventral abdomen via the application of 5% DNFB (50 μL) on days 1 and 2, followed by rechallenge in the right ear with 5% DNFB (20 μL) on day 5. Beginning on day 1, immunized mice were intraperitoneally injected with the appropriate fisetin dose (in saline) once per day for 7 days. On day 7, ear swelling, transcription factor expression, Th17/Treg cell populations, and cytokine production were assessed in vivo. Results. Fisetin treatment significantly suppressed ear swelling and associated inflammatory cell infiltration, besides reducing the production of Th17 cytokines (IL-17, TNF-α, and IL-6) and the expression of the Th17 lineage transcription factor RORγt while simultaneously enhancing Treg-specific cytokine production (TGF-β and IL-10) and the expression of the Treg lineage transcription factor Foxp3, thereby restoring the Th17/Treg cell in ACD mice. Conclusions. These data indicate that fisetin exhibits immunomodulatory activity and can alter the Th17/Treg cell balance, highlighting its potential value as a treatment drug for ACD.

Reversal of cisplatin resistance by neferine/isoliensinine and their combinatorial regimens with cisplatin-induced apoptosis in cisplatin-resistant colon cancer stem cells (CSCs)

Cisplatin chemotherapy to the colorectal cancer cells (CRCs) is accompanied by dose-limiting adverse effects along with the acquisition of drug resistance implicating low therapeutic outcomes. The present study is aimed to evaluate the chemosensitizing efficacy of neferine/isoliensinine or combinatorial regimen of neferine/isoliensinine with cisplatin against CSCs (cisplatin resistant colon stem cells). CSCs were developed using pulse exposure of cisplatin to parental HCT-15 cells. Neferine/isoliensinine or combinatorial regimens of Neferine/isoliensinine and cisplatin exhibited a stronger cytotoxic activity against CSCs compared to control. IC₅₀ doses were found to be 6.5 μM for neferine, 12.5 μM for isoliensinine, and 120 μM for cisplatin respectively. Furthermore, the combinatorial regimen of a low dose of cisplatin (40 μM) with 4 μM neferine/8 μM isoliensinine induced cell death in a synergistic manner as described by isobologram. Neferine/isoliensinine could confer extensive intracellular reactive oxygen species generation in CSCs. Neferine/isoliensinine or combinatorial regimens dissipated mitochondrial membrane potential and enhanced intracellular [Ca²⁺ ]i, which were measured by spectroflurimetry. Furthermore, these combinatorial regimens induced a significant increase in the sub G0 phase of cell cycle arrest and PI uptake and alleviated the expression of ERCC1 in CSCs. Combinatorial regimens or neferine/isoliensinine treatments downregulated the cell survival protein expression (PI3K/pAkt/mTOR) and activated mitochondria-mediated apoptosis by upregulating Bax, cytochrome c, caspase-3, and PARP cleavage expression while downregulating the BCl-2 expression in CSCs. Our study confirms the chemosensitizing efficacy of neferine/isoliensinine or combinatorial regimens of neferine/isoliensinine with a low dose of cisplatin against CSCs.

The potential of Senolytics in transplantation

Older organs provide a substantial unrealized potential with the capacity to close the gap between demand and supply in organ transplantation. The potential of senolytics in improving age-related conditions has been shown in various experimental studies and early clinical trials. Those encouraging data may also be of relevance for transplantation. As age-differences between donor and recipients are not uncommon, aging may be accelerated in recipients when transplanting older organs; young organs may, at least in theory, have the potential to 'rejuvenate' old recipients. Here, we review the relevance of senescent cells and the effects of senolytics on organ quality, alloimmune responses and outcomes in solid organ transplantation. This article is part of the Special Issue - Senolytics - Edited by Joao Passos and Diana Jurk.

Immunosuppressant flavonoids from Scutellaria baicalensis

Some plants used in Traditional Chinese Medicine serve as treatment for disease states where a suppression of the cellular immune response is desired. However, the compounds responsible for the immunosuppressant effects of these plants are not necessarily known. The immunosuppressant compounds in the roots of Scutellaria baicalensis, one of the most promising plants identified in a previous screening, were tracked by HPLC activity profiling and concomitant on-line spectroscopic analysis. Compounds were then isolated by preparative chromatography, and structures elucidated by spectroscopic methods. Twelve flavonoids (5-16) were identified from the active time windows, and structurally related flavones 2, 4, and 17, and flavanones 1 and 3 were isolated from adjacent fractions. All flavonoids possessed an unusual substitution pattern on the B-ring, with an absence of substituents at C-3 and C-4. Compounds 11, 13, 14, and 16 inhibited T-cell proliferation (IC₅₀ values at 12.1-39 μM) at non-cytotoxic concentrations. The findings may support the use of S. baicalensis in disorders where a modulation of the cellular immune response is desirable.

Immunity boosting nutraceuticals: Current trends and challenges

The immune function of the human body is highly influenced by the dietary intake of certain nutrients and bioactive compounds present in foods. The preventive effects of these bioactive ingredients against various diseases have been well investigated. Functional foods are consumed across various diverse cultures, in some form or the other, which provide benefits greater than the basic nutritional needs. Novel functional foods are being developed using novel bioactive ingredients such as probiotics, polyunsaturated fatty acids, and various phytoconstituents, which have a range of immunomodulatory properties. Apart from immunomodulation, these ingredients also affect immunity by their antioxidant, antibacterial, and antiviral properties. The global pandemic of Severe Acute Respiratory Syndrome Coronavirus-2 has forced the scientific community to race against time to find a proper and effective drug or a vaccine. In this review, various non-pharmacological interventions using nutraceuticals and functional foods have been discussed. PRACTICAL APPLICATIONS: Despite a plethora of research being undertaken to understand the immunity boosting properties of the various bioactive present in food, the findings are not translating to nutraceutical products in the market. Immunity has proved to be one of the most important factors for the health and well-being of an individual, especially when the world has been under the grip of the novel coronavirus Severe Acute Respiratory Syndrome Coronavirus-2. The anti-inflammatory properties of various nutraceuticals can come out as potential inhibitors of the various inflammatory processes such as cytokine storms, usually being observed in COVID 19. This review gives an insight into how various nutraceuticals can help in the prevention of various diseases through different mechanisms. The lack of awareness and proper clinical trials pose a challenge to the nutraceutical industry. This review will help and encourage researchers to further design and develop various functional foods, which might help in building immunity.

Dietary Phytochemicals as a Potential Source for Targeting Cancer Stem Cells

The tumor microenvironment is composed of various types of cells that lead to tumor heterogeneity. In the middle of these populations, cancer stem cells play a vital role in the initiation and progression of cancer cells and are capable of self-renewal and differentiation processes. These cancer stem cells are resistant to conventional therapy such as chemotherapy and radiotherapy. To eradicate the cancer stem cells in the tumor environment, various natural product has been found in recent years. In this review, we have selected some of the natural products based on anticancer potential including targeting cancer cells and cancer stem cells. Further, this review explains the molecular mechanism of action of these natural products in various cancer stem cells. Therefore, targeting a multi-drug resistant cancer stem cell by natural products is a novel method to reduce drug resistance and adverse effect during conventional therapy.

miR-155 influences cell-mediated immunity in Balb/c mice treated with aflatoxin M1

Aflatoxin M1 (AFM1) is a 4-hydroxylated metabolite of aflatoxin B1 (AFB1). It induces various toxicological effects including immunotoxicity. In the present study, we investigated the effects of AFM1 on immune system and its modulation by MicroRNA (miR)-155. AFM1 was administered intraperitoneally at doses of 25 and 50 µg/kg for 28 days to Balb/c mice and different immune system parameters were analyzed. The levels of miR-155 and targeted proteins were evaluated in isolated T cells from spleens of mice. Spleen weight was reduced in mice exposed to AFM1 compared to negative control. Proliferation of splenocytes in response to phytohemagglutinin-A was reduced in mice exposed to AFM1. IFN-γ was decreased in mice exposed to AFM1, whereas IL-10 was increased. Concentration of IL-4 did not change different in mice exposed to AFM1 compared to negative control. Exposure to AFM1 reduced the expression of miR-155. Significant upregulation of phosphatidylinositol-3, 4, 5-trisphosphate 5-phosphatase 1 (Ship1) and suppressor of cytokine signaling 1 (Socs1) was observed in isolated T cells from spleens of mice treated with AFM1, but the transcription factor Maf (c-MAF) was not affected. These results suggest that miR-155 and targeted proteins might be involved in the immunotoxicity observed in mice exposed to AFM1.

New tricks of old drugs: Repurposing non-chemo drugs and dietary phytochemicals as adjuvants in anti-tumor therapies

Combination therapy has long been applied to enhance therapeutic effect and deal with the occurrence of multi-drug resistance in cancer treatment. However, the overlapping toxicity of multiple anticancer drugs to healthy tissues and increasing financial burden on patients emerged as major concerns. As promising alternatives to chemo agents, repurposed non-chemo drugs and dietary phytochemicals have been investigated as adjuvants to conventional anti-tumor therapeutics, offering a safe and economic strategy for combination therapy. In this review, we aim to highlight the advances in research about combination therapy using conventional therapeutics and repurposed drugs or phytochemicals for an enhanced anti-tumor efficacy, along with the mechanisms involved in the synergism. Beyond these, we outlined the potential challenges and solutions for clinical translation of the proposed combination therapy, providing a safe and affordable strategy to improve the reach of cancer therapy to low income regions with such new tricks of old drugs.

Flavonoids as Multi-Target Compounds: A Special Emphasis on their Potential as Chemo-adjuvants in Cancer Therapy

Flavonoids are low molecular weight, polyphenolic phytochemicals, obtained from secondary metabolism of various plant compounds. They have a spectrum of pharmacological efficacies, including potential anticancer efficacy. Natural flavonoids are present in fruits, vegetables, grains, bark, roots, stems, flowers, tea and wine. Flavonoids can attenuate or inhibit the initiation, promotion and progression of cancer by modulating various enzymes and receptors in diverse pathways that involve cellular proliferation, differentiation, apoptosis, inflammation, angiogenesis and metastasis. Furthermore, in vitro, flavonoids have been shown to reverse multidrug resistance when used as chemo-adjuvants. Flavonoids (both natural and synthetic analogues) interact with several oncogenic targets through dependent and independent mechanisms to mediate their anticancer efficacy in different types of cancer cells.

Recent Advances on the Anti-Inflammatory and Antioxidant Properties of Red Grape Polyphenols: In Vitro and In Vivo Studies

In this review, special emphasis will be placed on red grape polyphenols for their antioxidant and anti-inflammatory activities. Therefore, their capacity to inhibit major pathways responsible for activation of oxidative systems and expression and release of proinflammatory cytokines and chemokines will be discussed. Furthermore, regulation of immune cells by polyphenols will be illustrated with special reference to the activation of T regulatory cells which support a tolerogenic pathway at intestinal level. Additionally, the effects of red grape polyphenols will be analyzed in obesity, as a low-grade systemic inflammation. Also, possible modifications of inflammatory bowel disease biomarkers and clinical course have been studied upon polyphenol administration, either in animal models or in clinical trials. Moreover, the ability of polyphenols to cross the blood-brain barrier has been exploited to investigate their neuroprotective properties. In cancer, polyphenols seem to exert several beneficial effects, even if conflicting data are reported about their influence on T regulatory cells. Finally, the effects of polyphenols have been evaluated in experimental models of allergy and autoimmune diseases. Conclusively, red grape polyphenols are endowed with a great antioxidant and anti-inflammatory potential but some issues, such as polyphenol bioavailability, activity of metabolites, and interaction with microbiota, deserve deeper studies.

Fisetin, a 3,7,3',4'-Tetrahydroxyflavone Inhibits the PI3K/Akt/mTOR and MAPK Pathways and Ameliorates Psoriasis Pathology in 2D and 3D Organotypic Human Inflammatory Skin Models

Psoriasis is a chronic immune-mediated skin disease that involves the interaction of immune and skin cells, and is characterized by cytokine-driven epidermal hyperplasia, deviant differentiation, inflammation, and angiogenesis. Because the available treatments for psoriasis have significant limitations, dietary products are potential natural sources of therapeutic molecules, which can repair the molecular defects associated with psoriasis and could possibly be developed for its management. Fisetin (3,7,3',4'-tetrahydroxyflavone), a phytochemical naturally found in pigmented fruits and vegetables, has demonstrated proapoptotic and antioxidant effects in several malignancies. This study utilized biochemical, cellular, pharmacological, and tissue engineering tools to characterize the effects of fisetin on normal human epidermal keratinocytes (NHEKs), peripheral blood mononuclear cells (PBMC), and CD4+ T lymphocytes in 2D and 3D psoriasis-like disease models. Fisetin treatment of NHEKs dose- and time-dependently induced differentiation and inhibited interleukin-22-induced proliferation, as well as activation of the PI3K/Akt/mTOR pathway. Fisetin treatment of TNF-α stimulated NHEKs also significantly inhibited the activation of p38 and JNK, but had enhanced effect on ERK1/2 (MAPK). In addition, fisetin treatment significantly decreased the secretion of Th1/Th-17 pro-inflammatory cytokines, particularly IFN-γ and IL-17A by 12-O-tetradecanolylphorbol 13-acetate (TPA)-stimulated NHEKs and anti-CD3/CD28-activated human PBMCs. Furthermore, we established the in vivo relevance of fisetin functions, using a 3D full-thickness human skin model of psoriasis (FTRHSP) that closely mimics in vivo human psoriatic skin lesions. Herein, fisetin significantly ameliorated psoriasis-like disease features, and decreased the production of IL-17 by CD4+ T lymphocytes co-cultured with FTRHSP. Collectively, our data identify the prodifferentiative, antiproliferative, and anti-inflammatory effects of fisetin, via modulation of the PI3K-Akt-mTOR and p38/JNK pathways and the production of cytokines in 2D and 3D human skin models of psoriasis. These results suggest that fisetin has a great potential to be developed as an effective and inexpensive agent for the treatment of psoriasis and other related inflammatory skin disorders.

Immunomodulatory Effects of Flavonoids: Possible Induction of T CD4+ Regulatory Cells Through Suppression of mTOR Pathway Signaling Activity

The increasing rate of autoimmune disorders and cancer in recent years has been a controversial issue in all aspects of prevention, diagnosis, prognosis and treatment. Among dietary factors, flavonoids have specific immunomodulatory effects that might be of importance to several cancers. Over different types of immune cells, T lymphocytes play a critical role in protecting the immune system as well as in the pathogenesis of specific autoimmune diseases. One of the important mediators of metabolism and immune system is mTOR, especially in T lymphocytes. In the current review, we assessed the effects of flavonoids on the immune system and then their impact on the mTOR pathway. Flavonoids can suppress mTOR activity and are consequently able to induce the T regulatory subset.

Immunotoxicity of aflatoxin M1 : as a potent suppressor of innate and acquired immune systems in a subacute study

BACKGROUND

Although, to date, there have been several in vitro and in vivo studies of immunomodulatory effects of aflatoxin M₁ (AFB₁ ), little is known about the effect of AFM₁ on various aspects of innate and acquired immunity. In the present study, AFM₁ was administered intraperitoneally, at doses of 25 and 50 μg kg^-1 , body mass for 28 days and various immunological parameters were measured.

RESULTS

Several parameters related to immune function were suppressed: organ mass, cellularity of spleen, proliferation response to lipopolysaccaride and phytohemagglutinin-A, hemagglutination titer, delayed type of hypersensitivity response, spleen cell subtypes, serum hemolytic activity, serum immunoglobulin G level and cytokine production. AFM₁ did not cause changes in body mass, hematological parameters or the concentration of immunoglobulin M in blood serum.

CONCLUSIONS

Overall, the data suggested that AFM₁ suppressed innate and acquired immunity. Therefore, with respect to consumer safety, it is extremely important to further control the level of AFM₁ in milk, and this should be considered as a precedence for risk management actions. © 2018 Society of Chemical Industry.

Flavonoids as Th1/Th2 cytokines immunomodulators: A systematic review of studies on animal models

BACKGROUND

Flavonoids are naturally occurring compounds, extensively distributed in plants. T helper (Th)1 and Th2 cytokines balance plays an essential role in the reaction of inflammatory, allergic and infectious processes and transplantation rejection.

PURPOSE

This systematic review focuses on various classes of flavonoids with a view to evaluate whether Th1/Th2 cytokine-mediated pathways of immunoenhancement could reduce immune overwhelming reactions.

METHODS

Articles in English published from inception to December 2017 reporting flavonoids with immunomodulatory activity for the management of immune-mediated disorders were acquired from PubMed, EMBASE, Scopus and Web of Science and a animal experiments where Th1 and Th2 cytokines were investigated to assess the outcome of immunoregulatory therapy were included.

CHAPTERS

1809 publications were identified and 26 were included in this review. Ten articles described the effect of flavonoids on allergic inflammation in an animal model of asthma; eleven in vivo studies evaluated the immunomodulating and immunosuppressive effects of flavonoids on Th1/Th2 cytokines production and five reports described the regulatory role of flavonoids for Th1/Th2 cytokine responses to experimental arthritis and myocarditis. Modulation of Th1/Th2 cytokine balance, inhibition of eosinophil accumulation and remodeling of the airways and lungs, downregulation of Notch and PI3K signaling pathways, regulation of CD4 + /CD8 + lymphocytes ratio and decreasing inflammatory mediator expressions levels are among the most important immunopharmacological mechanisms for the retrieved flavonoids.

CONCLUSION

Naturally occurring flavonoids discussed in the present article have optimal immunomodulation to prevent immune-mediated disorders through management of Th1/Th2 cytokine balance.

Suppression of T lymphocyte activation by 3-chloro-1,2-propanediol mono- and di-palmitate esters in vitro

This study investigated whether and how 3-chloro-1,2-propanediol (3-MCPD) fatty acid esters, a group of food contaminants formed during processing, might inhibit the immune system through suppressing T lymphocyte activation for the first time. Three 3-MCPD esters including 1-palmitoyl-3-chloropropanediol (1-pal), 2-palmitoyl-3-chloropropanediol (2-pal), and1,2-dipalmitoyl-3-chloropropanediol (dipal) were selected as the probe compounds to test the possible effects of fatty acid structure on their potential immune inhibitory effect. The results showed that 1-pal and 2-pal, but not dipal, significantly suppressed ConA-induced T lymphocyte proliferation, cell cycle activity, Th1 and Th2 cytokine secretion, CD4⁺ T cell populations, and the ratio of CD4⁺/CD8⁺ T cells under the experimental conditions. Moreover, Western blotting and immunofluorescence analyses revealed that 1-pal and 2-pal could inhibit the activation of ConA-stimulated mitogen-activated protein kinase (MAPK) and nuclear factor-kappa B (NF-κB) signaling pathways. In addition, 1-pal significantly suppressed DNFB-induced delayed-type hyper sensitivity (DTH) reaction characterized by the increased ear thickness and IFN-γ production in mice. These observations indicated that 3-MCPD esters exerted a negative effect on T lymphocyte-mediated immunity, and the immunosuppressive activities of 3-MCPD monopalmitates were stronger than 3-MCPD dipalmitate.

Mannan Derivatives Instruct Dendritic Cells to Induce Th1/Th2 Cells Polarization via Differential Mitogen-Activated Protein Kinase Activation

Mannan derived from fungal cell walls have potential uses as immunomodulating agents and vaccine adjuvants. Immunization with antigen conjugated to oxidized mannan (OM) or reduced mannan (RM) have induced differential immune responses in mice. Yet, the adjuvant effect and differences in molecular profiles of OM and RM on APCs is unresolved. Here, we investigated the response of mouse bone marrow-derived DCs to OM and RM. OM and RM stimulated DCs to produce differential Th1/Th2-inducing cytokines in vitro. OM and RM-activated DCs stimulated allogeneic T-cell Th1 and Th2 polarization reaction. OM instruct DCs to stimulate Th1 responses via IL-12p70 production, which depends on the phosphorylation of p38, RM barely induce IL-12p70, but IL-10 and IL-4, and magnitude of ERK phosphorylation, which results in a Th2 bias. These findings indicate that OM and RM were potent adjuvant capable of directly initiating DC activation Th1 and Th2 polarization respectively.

Flavonoids in Inflammatory Bowel Disease: A Review

Inflammatory bowel disease (IBD) is characterized by chronic inflammation of the intestine that compromises the patients’ life quality and requires sustained pharmacological and surgical treatments. Since their etiology is not completely understood, non-fully-efficient drugs have been developed and those that have shown effectiveness are not devoid of quite important adverse effects that impair their long-term use. In this regard, a growing body of evidence confirms the health benefits of flavonoids. Flavonoids are compounds with low molecular weight that are widely distributed throughout the vegetable kingdom, including in edible plants. They may be of great utility in conditions of acute or chronic intestinal inflammation through different mechanisms including protection against oxidative stress, and preservation of epithelial barrier function and immunomodulatory properties in the gut. In this review we have revised the main flavonoid classes that have been assessed in different experimental models of colitis as well as the proposed mechanisms that support their beneficial effects.

Neurotoxin from Naja naja atra venom inhibits skin allograft rejection in rats

BACKGROUND

Recent studies reported that Naja naja atra venom (NNAV) regulated immune function and had a therapeutic effect on adjunctive arthritis and nephropathy. We hypothesized that NNAV and its active component, neurotoxin (NTX), might inhibit skin allograft rejection.

METHODS

Skin allografts were used to induce immune rejection in rats. In addition, mixed lymphocyte culture (MLC) was used to mimic immune rejection reaction in vitro. Both NNAV and NTX were orally given starting from 5days prior to skin allograft surgery.

RESULTS

The results showed that oral administration of NNAV or NTX prolonged the survival of skin allografts and inhibited inflammatory response. The production of Th1 cytokines (IFN-γ, IL-2) was also suppressed. NTX inhibited T-cell proliferation and CD4(+) T cell division induced by skin allografts. NTX also showed immunosuppressive activity in mixed lymphocyte culture. Atropine alone inhibited Con A-induced proliferation of T cells and potentiated NTX' s inhibitory effects on T cells, while pilocarpine only slightly enhanced Con A-induced T cell proliferation and partially reversed the inhibitory effect of NTX. On the other hand, neither nicotine nor mecamylamine had an influence on NTX's inhibitory effects on Con A-induced T cell proliferation in vitro. NTX inhibited T cell proliferation by arresting the cell cycle at the G0/G1 phase.

CONCLUSIONS

The present study revealed that NNAV and NTX suppressed skin allograft rejection by inhibiting T cell-mediated immune responses. These findings suggest both NNAV and NTX as potential immunosuppressants for preventing the immune response to skin allografts.

Differential Effects of Naja naja atra Venom on Immune Activity

Previous studies reported that Naja naja atra venom (NNAV) inhibited inflammation and adjuvant arthritis. Here we investigated the role of NNAV in regulation of immune responses in mice. Oral administration of NNAV to normal mice showed significant increase in natural killer cell activity, B lymphocyte proliferation stimulated by lipopolysaccharides, and antibody production in response to sheep red blood cells. Meanwhile, NNAV markedly decreased T lymphocyte proliferation stimulated by concanavalin A, arrested the cell cycle at G₀/G₁ phase, and suppressed CD4 and CD8 T cell divisions. Furthermore, NNAV inhibited the dinitrofluorobenzene-induced delayed-type hypersensitivity reaction. This modulation of immune responses may be partly attributed to the selective increase in Th1 and Th2 cytokines (IFN-γ, IL-4) secretion and inhibition of Th17 cytokine (IL-17) production. In dexamethasone-induced immunosuppressed mice, NNAV restored the concentration of serum IgG and IgM, while decreasing the percentage of CD4 and CD8 T-cell subsets. These results indicate that NNAV enhances the innate and humoral immune responses while inhibiting CD4 Th17 and CD8 T cell actions, suggesting that NNAV could be a potential therapeutic agent for autoimmune diseases.