The modulatory effects of caffeic acid on human monocytes and its involvement in propolis action

Objectives: Researchers have been interested in investigating the mechanisms of action of propolis and the compounds involved in its biological activity; however, the effect of its isolated constituents on human immune cells still deserves investigation. Thus, this study aimed to verify the action of caffeic acid on human monocytes in an attempt to verify its effects on the innate immunity, and to analyse its participation in propolis activity. Methods: Monocytes viability was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide method after incubation with caffeic acid. Cell markers expression by monocytes (Toll-like receptors (TLR)-2, TLR-4, human leukocyte antigen (HLA)-DR and CD80) was analysed by flow cytometry. TNF- and IL-10 production was determined by enzyme-linked immunosorbent assay and the activity of monocytes against Candida albicans was investigated after incubation with different concentrations of caffeic acid. Key findings: Caffeic acid downregulated TLR-2 and HLA-DR expression and inhibited cytokine production whereas it upregulated the fungicidal activity of monocytes, without affecting cell viability. Conclusions: Caffeic acid exerted an immunomodulatory action in human monocytes in the evaluated parameters depending on concentration, with no cytotoxic effects. Moreover, it was partially involved in propolis action.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

The immunomodulatory effect of propolis on receptors expression, cytokine production and fungicidal activity of human monocytes

ObjectivesPropolis is a beehive product and its immunomodulatory action has been documented; however, little is known concerning its mechanisms of action on human cells. Propolis influence on the initial events of the immune response was assessed, evaluating cell markers, cytokine production and the fungicidal activity of human monocytes.MethodsToll-like receptor (TLR)-2, TLR-4, human leukocyte antigen-DR and cluster of differentiation (CD)80 expression by human monocytes was assessed using a FACSCalibur flow cytometer, cytokine production (tumour necrosis factor (TNF)- and interleukin (IL)-10) was determined by ELISA and the candidacidal activity was investigated after monocytes incubation with propolis and challenged with Candida albicans. The role of TLR-2 and TLR-4 on propolis action was assessed as well.Key findingsPropolis upregulated TLR-4 and CD80 expression and affected TNF- and IL-10 production, depending on concentration. Propolis also increased the fungicidal activity of monocytes. Cytokine production was decreased by blocking TLR-4, whereas the fungicidal activity was affected by blocking TLR-2.ConclusionsPropolis exerted an immunomodulatory action on cell receptors, cytokine production and fungicidal activity of human monocytes without affecting cell viability and depending on concentration. TLR-2 and TLR-4 may be involved in its mechanism of action.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Propolis effects on pro-inflammatory cytokine production and Toll-like receptor 2 and 4 expression in stressed mice

Introduction: Propolis is a beehive product and its immunomodulatory action has been well documented; however, little is known concerning its activity on the immune system of stressed mice. This work investigated a possible role of propolis against the immunosuppressive effects induced by stress in mice, assessing the pro-inflammatory cytokine (IL-1 beta and IL-6) production and Toll-like receptor (TLR-2 and TLR-4) expression by spleen cells.Methods: BALB/c mice were divided into 3 groups: G1 was considered control; G2 was submitted to restraint stress for 3 days, and G3 was treated with propolis and immediately submitted to stress. After sacrifice, spleens were removed and TLR-2 and TLR-4 gene expression was analyzed, as well as the pro-inflammatory cytokine production. Serum corticosterone levels were determined by radioimmunoassay as a stress indicator.Results: Stressed mice, treated or not with propolis, produced higher corticosterone levels, whereas IL-1 beta and IL-6 production was inhibited. TLR-2 and TLR-4 expression was inhibited in stressed mice, while propolis exerted an immunorestorative role in TLR-4 expression. The immunosuppressive effects on IL-1 beta and IL-6 production and on TLR expression by stressed mice might have occurred due to a higher corticosterone production during stress.Conclusion: Propolis treatment did not antagonize the inhibitory effects on pro-inflammatory cytokine production, however it restored at least partially TLR2 mRNA expression and counteracted the inhibition on TLR-4 expression in stressed animals, contributing to the recognition of microorganisms during stressful conditions. (C) 2009 Elsevier B.V. All rights reserved.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

The effect of propolis on CCL5 and IFN-gamma expression by peripheral blood mononuclear cells from leishmaniasis patients

Objectives Mucocutaneous leishmaniasis is associated with a strong Th1 immune response to Leishmania, which modulates chemokines and their receptors expression, affecting their migratory capacity. There are no antileishmanial vaccines available and chemotherapy still relies on the potentially toxic pentavalent antimonials. Propolis is a bee product with immunomodulatory and antiparasite activities, and researchers have been attracted to its potential for the development of new drugs. This work investigated the effects of propolis on CCL5 and IFN-? expression by peripheral blood mononuclear cells (PBMC) in order to evaluate a possible immunomodulatory action of propolis in patients with leishmaniasis compared to healthy control subjects.Methods PBMC were incubated in the absence or presence of propolis and the evaluation of a possible cytotoxicity of propolis was carried out using MTT assay. The expression level of CCL5 and IFN-gamma was determined by real-time PCR.Key findings Our data indicated that propolis modulates the immune response of leishmaniasis patients in vitro, affecting CCL5 and IFN-gamma expression by PBMC.Conclusions Data suggested that propolis drives an anti-inflammatory response depending on concentration. Although propolis is a potential source of new and selective drugs for the treatment of leishmaniasis, its usefulness in the therapeutics should be further investigated.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Human Sensory Neuron-like Cells and Glycated Collagen Matrix as a Model for the Screening of Analgesic Compounds

Increased collagen-derived advanced glycation end-products (AGEs) are consistently related to painful diseases, including osteoarthritis, diabetic neuropathy, and neurodegenerative disorders. We have recently developed a model combining a two-dimensional glycated extracellular matrix (ECM-GC) and primary dorsal root ganglion (DRG) that mimicked a pro-nociceptive microenvironment. However, culturing primary cells is still a challenge for large-scale screening studies. Here, we characterized a new model using ECM-GC as a stimulus for human sensory-like neurons differentiated from SH-SY5Y cell lines to screen for analgesic compounds. First, we confirmed that the differentiation process induces the expression of neuron markers (MAP2, RBFOX3 (NeuN), and TUBB3 (β-III tubulin), as well as sensory neuron markers critical for pain sensation (TRPV1, SCN9A (Nav1.7), SCN10A (Nav1.8), and SCN11A (Nav1.9). Next, we showed that ECM-GC increased c-Fos expression in human sensory-like neurons, which is suggestive of neuronal activation. In addition, ECM-GC upregulated the expression of critical genes involved in pain, including SCN9A and TACR1. Of interest, ECM-GC induced substance P release, a neuropeptide widely involved in neuroinflammation and pain. Finally, morphine, the prototype opiate, decreased ECM-GC-induced substance P release. Together, our results suggest that we established a functional model that can be useful as a platform for screening candidates for the management of painful conditions