Green propolis increases myeloid suppressor cells and CD4+Foxp3+ cells and reduces Th2 inflammation in the lungs after allergen exposure

Phytomedical compounds as promising therapeutic agents for COVID-19 targeting angiotensin-converting enzyme 2: a review

AIMS

The aim of the present review was to highlight natural product investigations in silico and in vitro to find plants and chemicals that inhibit or stimulate angiotensin-converting enzyme 2 (ACE-2).

BACKGROUND

The global reduction of incidents and fatalities attributable to infections with SARS-CoV-2 is one of the most public health problems. In the absence of specific therapy for coronavirus disease 2019 (COVID-19), phytocompounds generated from plant extracts may be a promising strategy worth further investigation, motivating researchers to evaluate the safety and anti-SARS-CoV-2 effectiveness of these ingredients.

OBJECTIVE

To review phytochemicals in silico for anti-SARS-CoV-2 activity and to assess their safety and effectiveness in vitro and in vivo.

METHODS

The present review was conducted using various scientific databases and studies on anti-SARS-CoV-2 phytochemicals were analyzed and summarized. The results obtained from the in silico screening were subjected to extraction, isolation, and purification. The in vitro studies on anti-SarcoV-2 were also included in this review. In addition, the results of this research were interpreted, analyzed, and documented on the basis of the bibliographic information obtained.

RESULTS

This review discusses recent research on using natural remedies to cure or prevent COVID-19 infection. The literature analysis shows that the various herbal preparations (extracts) and purified compounds can block the replication or entrance of the virus directly to carry out their anti-SARS-CoV-2 effects. It is interesting to note that certain items can prevent SARS-CoV-2 from infecting human cells by blocking the ACE-2 receptor or the serine protease TMPRRS2. Moreover, natural substances have been demonstrated to block proteins involved in the SARS-CoV-2 life cycle, such as papain- or chymotrypsin-like proteases.

CONCLUSION

The natural products may have the potential for use singly or in combination as alternative drugs to treat/prevent COVID-19 infection, including blocking or stimulating ACE-2. In addition, their structures may provide indications for the development of anti-SARS-CoV-2 drugs.

Productions of Th2 cytokines, IL-4 and IL-10, were enhanced via the function of IL-2 from anti-CD3 antibody-stimulated mouse spleen cells treated with caffeic acid phenethyl ester

OBJECTIVES

Interleukin (IL)-2 production by mouse spleen cells stimulated with an anti-CD3 antibody is significantly enhanced by caffeic acid phenethyl ester (CAPE), a major constituent of Chinese propolis (CP). In this study, we evaluated the functional significance of IL-2 in CAPE-treated activated spleen cells.

METHODS

Mouse spleen cells were stimulated with an anti-CD3 monoclonal antibody in the presence of CAPE. Cytokine production was examined using an enzyme-linked immunosorbent assay (ELISA). Messenger RNA level expression was examined via reverse transcription quantitative polymerase chain reaction (RT-PCR). IL-2 function was assessed using IL-2 and a neutralizing antibody. Spleen cell subsets were identified and characterized using flow cytometry.

RESULTS

CAPE treatment of anti-CD3 antibody-stimulated spleen cells reduced IFN-γ production, then enhanced IL-2 production, followed by enhancement of IL-4 and IL-10 production. The Th2 cytokine production enhancing effects of CAPE were completely abolished by addition of an anti-IL-2 neutralizing antibody. In the absence of CAPE, exogenously added IL-2 could enhance IL-4 production to a lesser degree, but did not stimulate IL-10 production, in stimulated spleen cells. Interestingly, CAPE significantly reduced the proportions of CD4+ and CD8+ cells, and increased those of CD4-CD8- cells among anti-CD3 stimulated spleen cells, in the presence or absence of anti-IL-2 neutralizing antibody treatment.

CONCLUSIONS

CAPE reduced IFN-γ production, then enhanced IL-4 and IL-10 production via the activity of specifically elevated IL-2 in stimulated spleen cells. CAPE exerted these effects in a CD4- CD8- cell specific manner.

Effects of Anatolian Propolis and Hypertonic Saline Combination Nasal Spray on Allergic Rhinitis Symptoms: A Prospective, Multicenter Study

Objectives: This study aimed to evaluate how Rhinapi nasal spray affects symptoms of allergic rhinitis. Methods: In this prospective, multicenter, observational study, 10,000 patients (comprising 5028 males and 4972 females) exhibiting symptoms of allergic rhinitis (namely, nasal discharge, sneezing, nasal itching, and nasal obstruction) from different centers in different regions of Turkey were enrolled in the study between March 2022 and March 2023. All the patients wanted to participate in the study and were administered Rhinapi one puff to each nostril three times a day, for a period of 3 weeks. Total symptom scores, quality of life (QoL) scores, and otolaryngological examination scores were evaluated before and 3 weeks after treatment. Results: The scores for discharge from the nose, sneezing, nasal pruritus, and blockage of the nose all indicated improvement when compared to pre-medication and post-medication. This difference achieved statistical significance (P < .001). The mean total symptom score fell following treatment (P < .001): whilst the score was 11.09 ± 3.41 before administering Rhinapi; after administration, the average score was 6.23 ± 2.41. The mean QoL scores also altered after medication (P < .001), improving from a mean value of 6.44 ± 1.55 to a mean of 7.31 ± 1.24. Significant improvement was also noted in the scores for conchal color and degree of edema after the treatment had been administered (P < .001). Conclusion: The study demonstrates that Rhinapi nasal spray decreases total symptom scores, and results in improved QoL and otolaryngological examination scores. Propolis spray may be recommended for patients with allergic rhinitis alongside other treatments.

Evaluation of the flexural strength of orthodontic acrylic resin incorporated with propolis nanoparticles: an in vitro study

AIM

Nanopropolis has become the subject of interest in medicine and dentistry as a natural product due to its outstanding properties, particularly antimicrobial activity. This study aimed at investigating the effect of nanopropolis on flexural strength of polymethyl methacrylate (PMMA).

The recent progress of myeloid-derived suppressor cell and its targeted therapies in cancers

Myeloid-derived suppressor cells (MDSCs) are an immature group of myeloid-derived cells generated from myeloid cell precursors in the bone marrow. MDSCs appear almost exclusively in pathological conditions, such as tumor progression and various inflammatory diseases. The leading function of MDSCs is their immunosuppressive ability, which plays a crucial role in tumor progression and metastasis through their immunosuppressive effects. Since MDSCs have specific molecular features, and only a tiny amount exists in physiological conditions, MDSC-targeted therapy has become a promising research direction for tumor treatment with minimal side effects. In this review, we briefly introduce the classification, generation and maturation process, and features of MDSCs, and detail their functions under various circumstances. The present review specifically demonstrates the environmental specificity of MDSCs, highlighting the differences between MDSCs from cancer and healthy individuals, as well as tumor-infiltrating MDSCs and circulating MDSCs. Then, we further describe recent advances in MDSC-targeted therapies. The existing and potential targeted drugs are divided into three categories, monoclonal antibodies, small-molecular inhibitors, and peptides. Their targeting mechanisms and characteristics have been summarized respectively. We believe that a comprehensive in-depth understanding of MDSC-targeted therapy could provide more possibilities for the treatment of cancer.

Propolis anti-inflammatory effects on MAGE-1 and retinoic acid-treated dendritic cells and on Th1 and T regulatory cells

Background

Propolis exhibits huge potential in the pharmaceutical industry. In the present study, its effects were investigated on dendritic cells (DCs) stimulated with a tumor antigen (MAGE-1) and retinoic acid (RA) and on T lymphocytes to observe a possible differential activation of T lymphocytes, driving preferentially to Th1 or Treg cells.

Methods

Cell viability, lymphocyte proliferation, gene expression (T-bet and FoxP3), and cytokine production by DCs (TNF-α, IL-10, IL-6 and IL-1β) and lymphocytes (IFN-γ and TGF-β) were analyzed.

Results

MAGE-1 and RA alone or in combination with propolis inhibited TNF-α production and induced a higher lymphoproliferation compared to control, while MAGE-1 + propolis induced IL-6 production. Propolis in combination with RA induced FoxP3 expression. MAGE-1 induced IFN-γ production while propolis inhibited it, returning to basal levels. RA inhibited TGF-β production, what was counteracted by propolis.

Conclusion

Propolis affected immunological parameters inhibiting pro-inflammatory cytokines and favoring the regulatory profile, opening perspectives for the control of inflammatory conditions.

Recent Update on the Anti-Inflammatory Activities of Propolis

In recent years, research has demonstrated the efficacy propolis as a potential raw material for pharmaceuticals and nutraceuticals. There is limited report detailing the mechanisms of action of propolis and its bioactive compounds in relation to their anti-inflammatory properties. Thus, the aim of the present review is to examine the latest experimental evidence (2017-2022) regarding the anti-inflammatory properties of propolis. A systematic scoping review methodology was implemented. After applying the exclusion criteria, a total of 166 research publications were identified and retrieved from Scopus, Web of Science, and Pubmed. Several key themes related to the anti-inflammatory properties of propolis were subsequently identified, namely in relation to cancers, oral health, metabolic syndrome, organ toxicity and inflammation, immune system, wound healing, and pathogenic infections. Based on the latest experimental evidence, propolis is demonstrated to possess various mechanisms of action in modulating inflammation towards the regulatory balance and anti-inflammatory environment. In general, we summarize that propolis acts as an anti-inflammatory substance by inhibiting and downregulating TLR4, MyD88, IRAK4, TRIF, NLRP inflammasomes, NF-κB, and their associated pro-inflammatory cytokines such as IL-1β, IL-6, IFN-γ, and TNF-α. Propolis also reduces the migration of immune cells such as macrophages and neutrophils, possibly by downregulating the chemokines CXCL9 and CXCL10.

Anti-Inflammatory Effect of Korean Propolis on Helicobacter pylori-Infected Gastric Mucosal Injury Mice Model

Propolis, a natural resinous substance obtained from a variety of buds and plants, has been reported to possess various biological functions. Several recent studies have demonstrated the inhibitory effects of propolis on the growth of Helicobacter pylori (H. pylori) in vitro; however, current research efforts on Korean propolis (KP) remain insufficient especially in vivo. Our study aims to investigate the anti-inflammatory effect and molecular mechanism of KP on mouse gastric mucosa during H. pylori infection. We examined an in vivo H. pylori-induced gastric mucosal injury mice model. We found that KP inhibited the growth of H. pylori and attenuated the expression of H. pylori virulence factors such as cytotoxin-associated gene A, encoding urease A subunit, surface antigen gene and neutrophil-activating protein A. Moreover, KP reduced both gross lesions and pathological scores in H. pylori-challenged mice. In addition, KP markedly restrained the production of pro-inflammatory cytokines and nitric oxide levels compared with an untreated H. pylori-infected group. In particular, we found that KP repressed the phosphorylation of IκBα and NF-κB p65 subunit, and subsequently suppressed their downstream target genes. Taken together, these findings demonstrate the beneficial effects of KP on inflammation through the inhibition of NF-κB signaling as well as inhibition of H. pylori growth in a mouse model infected with H. pylori. This suggests the potential application of KP as a natural supplement for patient’s suffering from gastric mucosal injury caused by H. pylori infection.

Allergic Inflammation: Effect of Propolis and Its Flavonoids

The incidence of allergic diseases and their complications are increasing worldwide. Today, people increasingly use natural products, which has been termed a "return to nature". Natural products with healing properties, especially those obtained from plants and bees, have been used in the prevention and treatment of numerous chronic diseases, including allergy and/or inflammation. Propolis is a multi-component resin rich in flavonoids, collected and transformed by honeybees from buds and plant wounds for the construction and adaptation of their nests. This article describes the current views regarding the possible mechanisms and multiple benefits of flavonoids in combating allergy and allergy-related complications. These benefits arise from flavonoid anti-allergic, anti-inflammatory, antioxidative, and wound healing activities and their effects on microbe-immune system interactions in developing host responses to different allergens. Finally, this article presents various aspects of allergy pathobiology and possible molecular approaches in their treatment. Possible mechanisms regarding the antiallergic action of propolis on the microbiota of the digestive and respiratory tracts and skin diseases as a method to selectively remove allergenic molecules by the process of bacterial biotransformation are also reported.

Development of propolis and essential oils containing oral/throat spray formulation against SARS-CoV-2 infection

A broad range of evidence has confirmed that natural products and essential oils might have the potential to suppress COVID-19 infection. Therefore, this study aimed to develop an oral/throat spray formulation for prophylactic use in the oral cavity or help treatment modalities. Based on a reference survey, several essential oils, a cold-pressed oil, and propolis were selected, and cytotoxicity and antiviral activity of each component and the developed spray formulation were examined against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection using Vero E6 cells. Anti-inflammatory, antimicrobial, and analgesic activities as well as mutagenicity and anti-mutagenicity of the formulation were analysed. Forty-three phenolics were identified in both propolis extract and oral/throat spray. The spray with 1:640-fold dilution provided the highest efficacy and the cytopathic effect was delayed for 54 h at this dilution, and the antiviral activity rate was 85.3%. A combination of natural products with essential oils at the right concentrations can be used as a supplement for the prevention of SARS-CoV-2 infection.

Can natural products modulate cytokine storm in SARS-CoV2 patients?

Currently, the number of cases and deaths of SARS-CoV2, especially among the chronic disease groups, due to aggressive SARS-CoV2 infection is increasing day by day. Various infections, particularly viral ones, cause a cytokine storm resulting in shortness of breath, bleeding, hypotension, and ultimately multi-organ failure due to over-expression of certain cytokines and necrosis factors. The most prominent clinical feature of SARS-CoV2 is the presence of elevated proinflammatory cytokines in the serum of patients with SARS-CoV2. Severe cases exhibit higher levels of cytokines, leading to a "cytokine storm" that further increases disease severity and causes acute respiratory distress syndrome, multiple organ failure, and death. Therefore, targeted cytokine production could be a potential therapeutic option for patients severely infected with SARS-CoV2. Given the current scenario, great scientific progress has been made in understanding the disease and its forms of treatment. Because of natural ingredients properties, they have the potential to be used as potential agents with the ability to modulate immune responses. Moreover, they can be used safely because they have no toxic effects, are biodegradable and biocompatible. However, these natural substances can continue to be used in the development of new therapies and vaccines. Finally, the aim and approach of this review article is to highlight current research on the possible use of natural products with promising potential as immune response activators. Moreover, consider the expected use of natural products when developing potential therapies and vaccines.

Enhanced production of IL-2 from anti-CD3 antibody-stimulated mouse spleen cells by artepillin C, a major component of Brazilian green propolis

OBJECTIVES

In this report, we attempt to clarify the immune modulatory effects of Brazilian green propolis (BGP) and its major component, artepillin C, on the cytokine production of anti-CD3 antibody-stimulated mouse spleen cells. We also estimate the physiological mechanism affecting artepillin C's upon the cells.

METHODS

Male C3H/HeN mouse spleen cells stimulated by antiCD3 monoclonal antibody were co-cultured with BGP, artepillin C, and HC030031, a transient receptor potential ankyrin 1 (TRPA1) Ca²⁺ channel antagonist. The synthesis of interferon (IFN)-γ, interleukin (IL)-6, IL-17, IL-4, IL-10, and IL-2 was assayed by enzyme-linked immunoassay. The expression of IL-2 mRNA and the protein product were examined by reverse transcription-quantitative polymerase chain reaction and Western blot analyses, respectively.

RESULTS

The production of IL-2 was markedly enhanced, while that of IL-4 and IL-10 was not significantly affected; by contrast, the production of IFN-γ, IL-6, and IL-17 was significantly reduced in the antibody-stimulated spleen cells treated with BGP at a non-cytostatic concentration. These effects were reproduced in the cells treated with artepillin C. The expression of IL-2 mRNA was unaffected; however, that of the protein was significantly enhanced in the artepillin C-treated cells compared to untreated control cells. The enhancement of protein expression and the production of IL-2 by artepillin C was significantly alleviated by adding HC030031.

CONCLUSIONS

Artepillin C is an important regulator of cytokine synthesis from activated spleen cells. The agent specifically augmented the expression of IL-2 via the Ca²⁺-permeable cation channel, TRPA1, at least in part, at the translational or secretion levels.

The antiviral and immunomodulatory activities of propolis: An update and future perspectives for respiratory diseases

Propolis is a complex natural product that possesses antioxidant, anti-inflammatory, immunomodulatory, antibacterial, and antiviral properties mainly attributed to the high content in flavonoids, phenolic acids, and their derivatives. The chemical composition of propolis is multifarious, as it depends on the botanical sources from which honeybees collect resins and exudates. Nevertheless, despite this variability propolis may have a general pharmacological value, and this review systematically compiles, for the first time, the existing preclinical and clinical evidence of propolis activities as an antiviral and immunomodulatory agent, focusing on the possible application in respiratory diseases. In vitro and in vivo assays have demonstrated propolis broad-spectrum effects on viral infectivity and replication, as well as the modulatory actions on cytokine production and immune cell activation as part of both innate and adaptive immune responses. Clinical trials confirmed propolis undeniable potential as an effective therapeutic agent; however, the lack of rigorous randomized clinical trials in the context of respiratory diseases is tangible. Since propolis is available as a dietary supplement, possible use for the prevention of respiratory diseases and their deleterious inflammatory drawbacks on the respiratory tract in humans is considered and discussed. This review opens up new perspectives on the clinical investigation of neglected propolis biological properties which, now more than ever, are particularly relevant with respect to the recent outbreaks of pandemic respiratory infections.

Anti-Allergic Properties of Propolis: Evidence From Preclinical and Clinical Studies

Allergic diseases are a global health burden with increasing prevalence. Side effects of available medications (antihistamines and steroids), lack of patients' perceived effectiveness and high cost of biologic therapies (omalizumab) are challenges to the clinical management of allergic diseases. As allergy symptoms persist for a long time, complementary and alternative medicine (CAM) such as propolis may be considered a potential prophylactic or therapeutic option to avoid long-term medication use. Propolis is a natural resinous substance produced by bees. Although propolis is well known to possess antioxidant, antimicrobial, and anticancer properties, its anti-allergic potential is not fully explored. Several preclinical studies demonstrated the therapeutic effects of propolis extracts against allergic inflammation, asthma, allergic rhinitis, atopic dermatitis, and food allergy, which may be partly attributed to their inhibitory effects on the activation of mast cells and basophils. Clinically, the consumption of propolis as a supplement or an adjunct therapy is safe and attenuates various pathological conditions in asthma. Such an approach may be adopted for atopic dermatitis and allergic rhinitis. Although flavonoids (chrysin, kaempferol, galangin, and pinocembrin) and cinnamic acid derivatives (artepillin C and caffeic acid phenethyl ester) can contribute to the anti-allergic activities, they may not be present in all propolis samples due to variations in the chemical composition. Future studies should relate the anti-allergic activity of propolis with its chemical contents. This mini-review summarizes and discusses existing preclinical and clinical studies reporting the anti-allergic activities of propolis to provide insights into its potential applications in allergic diseases.

The Potential Use of Propolis as a Primary or an Adjunctive Therapy in Respiratory Tract-Related Diseases and Disorders: A Systematic Scoping Review

Propolis is a resinous beehive product that is collected by the bees from plant resin and exudates, to protect and maintain hive homeostasis. Propolis has been used by humans therapeutically to treat many ailments including respiratory tract-related diseases and disorders. The aim of the present systematic scoping review is to evaluate the experimental evidence to support the use of propolis as a primary or an adjunctive therapy in respiratory tract-related diseases and disorders. After applying the exclusion criteria, 158 research publications were retrieved and identified from Scopus, Web of Science, Pubmed, and Google Scholar. The key themes of the included studies were pathogenic infection-related diseases and disorders, inflammation-related disorders, lung cancers, and adverse effects. Furthermore, the potential molecular and biochemical mechanisms of action of propolis in alleviating respiratory tract-related diseases and disorders are discussed. In conclusion, the therapeutic benefits of propolis have been demonstrated by various in vitro studies, in silico studies, animal models, and human clinical trials. Based on the weight and robustness of the available experimental and clinical evidence, propolis is effective, either as a primary or an adjunctive therapy, in treating respiratory tract-related diseases.

Artepillin C Reduces Allergic Airway Inflammation by Induction of Monocytic Myeloid-Derived Suppressor Cells

Propolis is a natural product produced by bees that is primarily used in complementary and alternative medicine and has anti-inflammatory, antibacterial, antiviral, and antitumoral biological properties. Some studies have reported the beneficial effects of propolis in models of allergic asthma. In a previous study, our group showed that green propolis treatment reduced airway inflammation and mucus secretion in an ovalbumin (OVA)-induced asthma model and resulted in increased regulatory T cells (Treg) and polymorphonuclear myeloid-derived suppressor cells (PMN-MDSC) frequencies in the lungs, two leukocyte populations that have immunosuppressive functions. In this study, we evaluated the anti-inflammatory effects of artepillin C (ArtC), the major compound of green propolis, in the context of allergic airway inflammation. Our results show that ArtC induces in vitro differentiation of Treg cells and monocytic MDSC (M-MDSC). Furthermore, in an OVA-induced asthma model, ArtC treatment reduced pulmonary inflammation, eosinophil influx to the airways, mucus and IL-5 secretion along with increased frequency of M-MDSC, but not Treg cells, in the lungs. Using an adoptive transfer model, we confirmed that the effect of ArtC in the reduction in airway inflammation was dependent on M-MDSC. Altogether, our data show that ArtC exhibits an anti-inflammatory effect and might be an adjuvant therapy for allergic asthma.

Baccharin and p-coumaric acid from green propolis mitigate inflammation by modulating the production of cytokines and eicosanoids

ETHNOPHARMACOLOGICAL RELEVANCE

Green propolis is produced by Apis mellifera honeybees using Baccharis dracunculifolia D.C. (Asteraceae) as substrate. This Southern Brazilian native plant and green propolis have been used in traditional medicine to treat gastric diseases, inflammation and liver disorders.

AIM OF THE STUDY

Investigate the effects of baccharin (Bac) or p-coumaric acid (pCA) isolated from B. dracunculifolia D.C. (Asteraceae) over the inflammation induced by lipopolysaccharide (LPS) in vivo.

MATERIALS AND METHODS

Inflammation was induced by LPS injection into air-pouches in mice, which were subsequently treated with Bac or pCA. Lavage fluid was collected from air pouches for the quantification of cellular influx via microscopy, and quantification of inflammatory mediators via colorimetric methods, ELISA and liquid chromatography-tandem mass spectrometry (LC-MS/MS).

RESULTS

LPS-induced inflammation increased cellular influx and increased the levels of parameters related to vascular permeability and edema formation, such as nitric oxide (NO) and protein extravasation. Moreover, LPS increased the levels of cytokines and eicosanoids in the air-pouches. Importantly, both Bac and pCA suppressed the infiltration of neutrophils, production of NO and protein extravasation. Notably, the compounds promote differential regulation of cytokine and eicosanoid production.

CONCLUSIONS

Our results suggest that Bac from green propolis directly affects inflammation by inhibiting the production of cytokines and eicosanoids, while pCA may exert direct, but also indirect effects on inflammation by stimulating the production of regulatory effectors such as interkeukin-10 in vivo.

Immunomodulatory effect of standardized C. asiatica extract on a promotion of regulatory T cells in rats

Background

ECa 233 is a standardized extract of C. asiatica containing the triterpenoid glycosides, madecassoside to asiaticoside in the ratio of (1.5 ± 0.5):1. Anti-inflammatory activities of ECa 233 have been reported; however the immunomodulatory effects of ECa 233 on regulatory T cells, which have a pivotal role in immune regulation, has not been elucidated. Therefore, we investigated the effects of ECa 233 on regulatory T cells that may provide benefits in autoimmune and chronic inflammatory diseases.

Methods

ECa 233 was prepared as oral suspension in 0.5% carboxymethylcellulose and administered to male Wistar rats via oral gavage. The pharmacokinetics and toxicity of ECa 233 were evaluated. Splenic lymphocytes were isolated and analyzed by flow cytometry and qPCR to determine the immunomodulatory effects of ECa 233 on regulatory T cells.

Results

All rats had good tolerability to ECa 233 and other test preparations. The pharmacokinetic study showed low oral bioavailability for both triterpenoids, with the maximum plasma concentration reached at 4 h for asiaticoside and at 0.5 h for madecassoside. Multiple oral administration of ECa 233 reduced the frequency of T cells, particularly CD8 T cells in rats. ECa 233 enhanced the percentage of regulatory T cells, characterized by high expression of CD25⁺ and upregulation of FoxP3 gene.

Conclusions

The present study demonstrated that ECa 233 possesses immunosuppressive properties by enhancing regulatory T cells. These results provide in vivo evidence for the anti-inflammatory action of ECa 233, in line with previously reports, and the potential uses of ECa 233 in the treatment of chronic inflammatory and autoimmune diseases.

Propolis increases Foxp3 expression and lymphocyte proliferation in HIV-infected people: A randomized, double blind, parallel-group and placebo-controlled study

HIV infection and the prolonged use of antiretroviral therapy (ART) contribute to persistent inflammation and immune deregulation in people living with HIV/AIDS (PLWHA). Propolis is a bee product with plenty of biological properties, including immunomodulatory and anti-inflammatory action. This work aimed to evaluate possible changes in the immune/inflammatory response in PLWHA under ART after propolis intake. Asymptomatic PLWHA were double-blindly randomized into parallel groups receiving propolis (500 mg/day, n = 20) for 3 months or placebo (n = 20). Plasma cytokines (TNF-α, IL-2, IL-4, IL-6, IL-10 and IL17) were evaluated by cytometric bead array; cytokine production by PBMC (IFN-γ, IL-5, IL-17, IL-10, IL-1β, IL-18, and IL-33) was assessed by ELISA; gene expression (T-bet, GATA-3, RORγt and Foxp3) was determined by RT-qPCR, and cell proliferation was analysed by flow cytometry using CFSE staining. The average of gender, age, CD4⁺/CD8⁺ T cell count, time of diagnosis and treatment were similar in both groups. No differences were observed in cytokine levels nor in inflammasome activation. However, Pearson's correlation showed that IL-10 was directly correlated to CD4⁺ T cell count and inversely to IFN-γ after treatment with propolis. Foxp3 expression and lymphocyte proliferation increased in the propolis group. Data suggested that daily propolis consumption may improve the immune response and decrease the inflammatory status in asymptomatic PLWHA under ART.

Anti-Viral and Immunomodulatory Properties of Propolis: Chemical Diversity, Pharmacological Properties, Preclinical and Clinical Applications, and In Silico Potential against SARS-CoV-2

Propolis, a resin produced by honeybees, has long been used as a dietary supplement and folk remedy, and more recent preclinical investigations have demonstrated a large spectrum of potential therapeutic bioactivities, including antioxidant, antibacterial, anti-inflammatory, neuroprotective, immunomodulatory, anticancer, and antiviral properties. As an antiviral agent, propolis and various constituents have shown promising preclinical efficacy against adenoviruses, influenza viruses, respiratory tract viruses, herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2), human immunodeficiency virus (HIV), and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Over 300 chemical components have been identified in propolis, including terpenes, flavonoids, and phenolic acids, with the specific constituent profile varying widely according to geographic origin and regional flora. Propolis and its constituents have demonstrated potential efficacy against SARS-CoV-2 by modulating multiple pathogenic and antiviral pathways. Molecular docking studies have demonstrated high binding affinities of propolis derivatives to multiple SARS-CoV-2 proteins, including 3C-like protease (3CLpro), papain-like protease (PLpro), RNA-dependent RNA polymerase (RdRp), the receptor-binding domain (RBD) of the spike protein (S-protein), and helicase (NSP13), as well as to the viral target angiotensin-converting enzyme 2 (ACE2). Among these compounds, retusapurpurin A has shown high affinity to 3CLpro (ΔG = -9.4 kcal/mol), RdRp (-7.5), RBD (-7.2), NSP13 (-9.4), and ACE2 (-10.4) and potent inhibition of viral entry by forming hydrogen bonds with amino acid residues within viral and human target proteins. In addition, propolis-derived baccharin demonstrated even higher binding affinity towards PLpro (-8.2 kcal/mol). Measures of drug-likeness parameters, including metabolism, distribution, absorption, excretion, and toxicity (ADMET) characteristics, also support the potential of propolis as an effective agent to combat COVID-19.

Experimental Evidence for Therapeutic Potentials of Propolis

Propolis is produced by honeybees from materials collected from plants they visit. It is a resinous material having mixtures of wax and bee enzymes. Propolis is also known as bee glue and used by bees as a building material in their hives, for blocking holes and cracks, repairing the combs and strengthening their thin borders. It has been extensively used since ancient times for different purposes in traditional human healthcare practices. The quality and composition of propolis depend on its geographic location, climatic zone and local flora. The New Zealand and Brazilian green propolis are the two main kinds that have been extensively studied in recent years. Their bioactive components have been found to possess a variety of therapeutic potentials. It was found that Brazilian green propolis improves the cognitive functions of mild cognitive impairments in patients living at high altitude and protects them from neurodegenerative damage through its antioxidant properties. It possesses artepillin C (ARC) as the key component, also known to possess anticancer potential. The New Zealand propolis contains caffeic acid phenethyl ester (CAPE) as the main bioactive with multiple therapeutic potentials. Our lab performed in vitro and in vivo assays on the extracts prepared from New Zealand and Brazilian propolis and their active ingredients. We provided experimental evidence that these extracts possess anticancer, antistress and hypoxia-modulating activities. Furthermore, their conjugation with γCD proved to be more effective. In the present review, we portray the experimental evidence showing that propolis has the potential to be a candidate drug for different ailments and improve the quality of life.

Natural products and phytochemicals as potential anti-SARS-CoV-2 drugs

The current pandemic responsible for the crippling of the health care system is caused by the novel SARS‐CoV‐2 in 2019 and leading to coronavirus disease 2019 (COVID‐19). The virus enters into humans by attachment of its Spike protein (S) to the ACE receptor present on the lung epithelial cell surface followed by cleavage of S protein by the cellular transmembrane serine protease (TMPRSS2). After entry, the SARS‐CoV‐2 RNA genome is released into the cytosol, where it highjacks host replication machinery for viral replication, assemblage, as well as the release of new viral particles. The major drug targets that have been identified for SARS‐CoV‐2 through host‐virus interaction studies include 3CLpro, PLpro, RNA‐dependent RNA polymerase, and S proteins. Several reports of natural compounds along with synthetic products have displayed promising results and some of them are Tripterygium wilfordii, Pudilan Xiaoyan Oral Liquid, Saponin derivates, Artemisia annua, Glycyrrhiza glabra L., Jinhua Qinggan granules, Xuebijing, and Propolis. This review attempts to disclose the natural products identified as anti‐SARS‐CoV‐2 based on in silico prediction and the effect of a variety of phytochemicals either alone and/or in combination with conventional treatments along with their possible molecular mechanisms involved for both prevention and treatment of the SARS‐CoV‐2 disease.

Preliminary Study on the In Vitro Antitumor Effects of Nidus Vespae on Gastric Cancer

Objective

The aim of this study was to investigate the in vitro antitumor effects of Nidus Vespae on gastric cancer and its ability to promote immune function.

Methods

Cell viability was detected by the Cell Counting Kit-8 (CCK-8) assay. Cell cycle distribution and apoptosis were detected using flow cytometry. The THP-1 human monocytic cell line was used as a source of monocytic effector cells for analyzing proliferation and dendritic cell (DC) induction. Enzyme-linked immunosorbent assay was used to detect cytokine production, and multicolor flow cytometry was used to study the phenotype and functionality of THP-1 DCs.

Results

A high concentration (>10 mg/mL) of Nidus Vespae decoction (NVD) inhibited SGC-7901 gastric cancer cell growth by inducing G2/M cell cycle arrest and apoptosis. However, a low concentration (≤10 mg/mL) of NVD significantly increased the proliferative ability of THP-1 in serum-containing medium and caused an increase in dendritic protrusions with the typical morphology of DCs compared to the negative control in serum-free medium. The THP-1 DCs had significantly increased expression of cluster of differentiation 11c (CD11c), CD40, CD80, CD83, and CD86, as well as secretion of tumor necrosis factor-alpha. Furthermore, the supernatant of THP-1 DCs significantly inhibited the proliferation of gastric cancer cells by inducing apoptosis and G1/S cell cycle arrest.

Conclusions

Our findings suggest that NVD not only directly inhibits the growth of gastric cancer cells but also exerts indirect antitumor effects by enhancing immune function. These results provide an important theoretical basis for the clinical application of Nidus Vespae in gastric cancer treatment.

Brazilian green propolis promotes TNFR2 expression on regulatory T cells

FoxP3+ regulatory T cells (Tregs) are needed to suppress inflammatory diseases and maintain immune homeostasis. The suppressive function of Tregs can be used to control autoimmune or inflammatory diseases; therefore, it is well studied how Tregs can be artificially up- or downregulated in vitro and in vivo, by using antibodies, chemical compounds, foods, and natural resources. Propolis is a famous functional food that has an anti-inflammatory effect. However, the influences of propolis on Treg function have not been fully evaluated so far. Here, we demonstrated that Brazilian green propolis increases TNFR2 expression in Tregs via the IRF4/cMyc axis, and artepillin C was a major effective component of propolis on Tregs. These results indicate that propolis and artepillin C have the potential as Treg activators via TNFR2 expression and may be useful for the prevention and/or therapy of autoimmune or inflammatory diseases.

Propolis antiviral and immunomodulatory activity: a review and perspectives for COVID-19 treatment

OBJECTIVES

Viral outbreaks are a frequent concern for humans. A great variety of drugs has been used to treat viral diseases, which are not always safe and effective and may induce adverse effects, indicating the need for new antiviral drugs extracted from natural sources. Propolis is a bee-made product exhibiting many biological properties. An overview of viruses, antiviral immunity, propolis safety and its immunomodulatory and antiviral action is reported, as well as perspectives for coronavirus disease 2019 (COVID-19) treatment. PubMed platform was used for data collection, searching for the keywords "propolis", "virus", "antiviral", "antimicrobial" and "coronavirus".

KEY FINDINGS

Propolis is safe and exerts antiviral and immunomodulatory activity; however, clinical trials should investigate its effects on individuals with viral diseases, in combination or not with antiviral drugs or vaccines.

SUMMARY

Regarding COVID-19, the effects of propolis should be investigated directly on the virus in vitro or on infected individuals alone or in combination with antiviral drugs, due to its immunomodulatory and anti-inflammatory action. Propolis administration simultaneously with vaccines should be analyzed, due to its adjuvant properties, to enhance the individuals' immune response. The search for therapeutic targets may be useful to find out how propolis can help to control COVID-19.

The diverse roles of myeloid derived suppressor cells in mucosal immunity

The mucosal immune system plays a vital role in protecting the host from the external environment. Its major challenge is to balance immune responses against harmful and harmless agents and serve as a 'homeostatic gate keeper'. Myeloid derived suppressor cells (MDSCs) are a heterogeneous population of undifferentiated cells that are characterized by an immunoregulatory and immunosuppressive phenotype. Herein we postulate that MDSCs may be involved in shaping immune responses related to mucosal immunity, due to their immunomodulatory and tissue remodeling functions. Until recently, MDSCs were investigated mainly in cancerous diseases, where they induce and contribute to an immunosuppressive and inflammatory environment that favors tumor development. However, it is now becoming clear that MDSCs participate in non-cancerous conditions such as chronic infections, autoimmune diseases, pregnancy, aging processes and immune tolerance to commensal microbiota at mucosal sites. Since MDSCs are found in the periphery only in small numbers under normal conditions, their role is highlighted during pathologies characterized by acute or chronic inflammation, when they accumulate and become activated. In this review, we describe several aspects of the current knowledge characterizing MDSCs and their involvement in the regulation of the mucosal epithelial barrier, their crosstalk with commensal microbiota and pathogenic microorganisms, and their complex interactions with a variety of surrounding regulatory and effector immune cells. Finally, we discuss the beneficial and harmful outcomes of the MDSC regulatory functions in diseases affecting mucosal tissues. We wish to illuminate the pivotal role of MDSCs in mucosal immunity, the limitations in our understanding of all the players and the intricate challenges stemming from the complex interactions of MDSCs with their environment.

Efficacy of Brazilian green propolis (EPP-AF®) as an adjunct treatment for hospitalized COVID-19 patients: A randomized, controlled clinical trial

Background

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) promotes challenging immune and inflammatory phenomena. Though various therapeutic possibilities have been tested against coronavirus disease 2019 (COVID-19), the most adequate treatment has not yet been established. Propolis is a natural product with considerable evidence of immunoregulatory and anti-inflammatory activities, and experimental data point to potential against viral targets. We hypothesized that propolis can reduce the negative effects of COVID-19.

Methods

In a randomized, controlled, open-label, single-center trial, hospitalized adult COVID-19 patients were treated with a standardized green propolis extract (EPP-AF®️) as an adjunct therapy. Patients were allocated to receive standard care plus an oral dose of 400 mg or 800 mg/day of green propolis for seven days, or standard care alone. Standard care included all necessary interventions, as determined by the attending physician. The primary end point was the time to clinical improvement, defined as the length of hospital stay or oxygen therapy dependency duration. Secondary outcomes included acute kidney injury and need for intensive care or vasoactive drugs. Patients were followed for 28 days after admission.

Results

We enrolled 124 patients; 40 were assigned to EPP-AF®️ 400 mg/day, 42 to EPP-AF®️ 800 mg/day, and 42 to the control group. The length of hospital stay post-intervention was shorter in both propolis groups than in the control group; lower dose, median 7 days versus 12 days (95% confidence interval [CI] −6.23 to −0.07; p = 0.049) and higher dose, median 6 days versus 12 days (95% CI −7.00 to −1.09; p = 0.009). Propolis did not significantly affect the need for oxygen supplementation. In the high dose propolis group, there was a lower rate of acute kidney injury than in the controls (4.8 vs 23.8%), (odds ratio [OR] 0.18; 95% CI 0.03–0.84; p = 0.048). No patient had propolis treatment discontinued due to adverse events.

Conclusions

Addition of propolis to the standard care procedures resulted in clinical benefits for the hospitalized COVID-19 patients, especially evidenced by a reduction in the length of hospital stay. Consequently, we conclude that propolis can reduce the impact of COVID-19.

New Insights Into Potential Benefits of Bioactive Compounds of Bee Products on COVID-19: A Review and Assessment of Recent Research

The recent emergence of COVID-19 represents one of the biggest challenges facing the world today. Despite the recent attempts to understand the epidemiological pattern and pathogenesis of the disease, detailed data about the physiology and pathology of the disease is still out of reach. Moreover, the lack of a widespread vaccine prompts an urgent call for developing a proper intervention strategy against the virus. Importantly, identification of novel molecules that target replication of the virus represents one of the promising strategies for the control this pandemic crisis. Among others, honey bee products contain numerous bioactive compounds such as propolis and several phenolic compounds that possess a wide range of therapeutic properties for combating various pathological disorders and infectious agents. The intention of the present review is to highlight the stages of SARS-CoV-2 lifecycle, the molecular mechanisms explaining the health benefits of honey bee products on COVID-19 physiology and pathology and the possible limitations. Further future research is suggested to explore more about bee natural bioactive compounds as potential candidates against SARS-CoV-2.

Propolis and its potential against SARS-CoV-2 infection mechanisms and COVID-19 disease: Running title: Propolis against SARS-CoV-2 infection and COVID-19

Propolis, a resinous material produced by honey bees from plant exudates, has long been used in traditional herbal medicine and is widely consumed as a health aid and immune system booster. The COVID-19 pandemic has renewed interest in propolis products worldwide; fortunately, various aspects of the SARS-CoV-2 infection mechanism are potential targets for propolis compounds. SARS-CoV-2 entry into host cells is characterized by viral spike protein interaction with cellular angiotensin-converting enzyme 2 (ACE2) and serine protease TMPRSS2. This mechanism involves PAK1 overexpression, which is a kinase that mediates coronavirus-induced lung inflammation, fibrosis, and immune system suppression. Propolis components have inhibitory effects on the ACE2, TMPRSS2 and PAK1 signaling pathways; in addition, antiviral activity has been proven in vitro and in vivo. In pre-clinical studies, propolis promoted immunoregulation of pro-inflammatory cytokines, including reduction in IL-6, IL-1 beta and TNF-α. This immunoregulation involves monocytes and macrophages, as well as Jak2/STAT3, NF-kB, and inflammasome pathways, reducing the risk of cytokine storm syndrome, a major mortality factor in advanced COVID-19 disease. Propolis has also shown promise as an aid in the treatment of various of the comorbidities that are particularly dangerous in COVID-19 patients, including respiratory diseases, hypertension, diabetes, and cancer. Standardized propolis products with consistent bioactive properties are now available. Given the current emergency caused by the COVID-19 pandemic and limited therapeutic options, propolis is presented as a promising and relevant therapeutic option that is safe, easy to administrate orally and is readily available as a natural supplement and functional food.

Souto E, Cardoso JC. Red Propolis and Its Dyslipidemic Regulator Formononetin: Evaluation of Antioxidant Activity and Gastroprotective Effects in Rat Model of Gastric Ulcer

Propolis has various pharmacological properties of clinical interest, and is also considered a functional food. In particular, hydroalcoholic extracts of red propolis (HERP), together with its isoflavonoid formononetin, have recognized antioxidant and anti-inflammatory properties, with known added value against dyslipidemia. In this study, we report the gastroprotective effects of HERP (50–500 mg/kg, p.o.) and formononetin (10 mg/kg, p.o.) in ethanol and non-steroidal anti-inflammatory drug-induced models of rat ulcer. The volume, pH, and total acidity were the evaluated gastric secretion parameters using the pylorus ligature model, together with the assessment of gastric mucus contents. The anti-Helicobacter pylori activities of HERP were evaluated using the agar-well diffusion method. In our experiments, HERP (250 and 500 mg/kg) and formononetin (10 mg/kg) reduced (p < 0.001) total lesion areas in the ethanol-induced rat ulcer model, and reduced (p < 0.05) ulcer indices in the indomethacin-induced rat ulcer model. Administration of HERP and formononetin to pylorus ligature models significantly decreased (p < 0.01) gastric secretion volumes and increased (p < 0.05) mucus production. We have also shown the antioxidant and anti-Helicobacter pylori activities of HERP. The obtained results indicate that HERP and formononetin are gastroprotective in acute ulcer models, suggesting a prominent role of formononetin in the effects of HERP.

Preparation, statistical optimization, in vitro characterization, and in vivo pharmacological evaluation of solid lipid nanoparticles encapsulating propolis flavonoids: a novel treatment for skin edema

Propolis is a natural resinous product and exerts anti-inflammatory properties. The aim of this study is formulation and characterization of solid lipid nanoparticles (SLNs) encapsulating propolis flavonoids (PFs), intended for topical treatment of skin edema. The nanoparticles were prepared and statistically optimized using Box-Behnken response surface methodology. The in vitro release profile of the optimized nanoparticles was investigated. Cytotoxicity of nanoparticles on HSF-PI 18 cell line was determined. Permeation and penetration of nanoparticles across the incised skin were measured. Finally, the nanoparticles were incorporated into a pharmaceutical hydrogel formulation and the in vivo efficacy in reduction of skin edema was determined. The size, PdI, zeta potential, entrapment efficiency (EE%) and loading efficiency (LE %) of the optimized nanoparticles were 111.3 ± 19.35 nm, 0.34 ± 0.005, -24.17 ± 3.3 mV, 73.5 ± 0.86%, and 3.2 ± 0.27%, respectively. Data obtained through in vitro release study suggested a burst release followed by a prolonged release behavior up to 24 h post incubation time interval. The prepared SLNs exhibited no cytotoxicity on HSF-PI 18 cell line. Ex vivo permeation and penetration study of nanoparticles across the incised skin showed approximately a 2.5-fold and a 3-fold increase in cumulative amount of transport and cumulative amount of skin penetration, respectively. Finally, in vivo studies in rat models, showed a threefold reduction in volume of the edema in animals treated with SLNs. The obtained data revealed that the prepared SNs entrapping PFs, exert high skin targeting effects, prolonged anti-inflammatory properties and therefore high efficiency in treatment of skin edema.