Propolis modulates NOS2/arginase-1 pathway in tropomyosin-induced experimental autoimmune uveitis.

In this study, we evaluated the preventive and curative effects of ethanolic extract of Propolis (EEP) during α-Tropomyosin-induced uveitis in an experimental model using Wistar rats, through the regulation of inducible nitric oxide synthase (NOS2) and arginase-1. In this context, rats received daily injection of EEP (100 mg/kg) for 5 days prior to immunization or for 9 days commencing 5 days post immunization with α-Tropomyosin extract, then were sacrificed at day 14. Histological examination, NOS2, arginase-1, and nuclear factor-κB (NF-κB) expression were evaluated in the retinas. Plasmatic production of nitric oxide (NO), urea, IL-4, and TNF-α was assessed. We have found that treatment with EEP substantially reduced the retinal histological damages induced by α-Tropomyosin. In the same context, a significant decrease of NO and TNF-α levels was noticed. Interestingly, EEP down-modulated NOS2 and NF-κB expression in retina. Also, an increase in urea and IL-4 levels was concomitant to an up-modulation of arginase-1 expression. Hence, it appears that EEP attenuated retinal damages through the induction of Th2 response and the inhibition of NF-κB/NOS2 pathway.

Ex vivo immunomodulatory effect of ethanolic extract of propolis during Celiac Disease: involvement of nitric oxide pathway.

Celiac Disease (CeD) is a chronic immune-mediated enteropathy, in which dietary gluten induces an inflammatory reaction, predominantly in the duodenum. Propolis is a resinous hive product, collected by honeybees from various plant sources. Propolis is well-known for its anti-inflammatory, anti-oxidant and immunomodulatory effects, due to its major compounds, polyphenols and flavonoids. The aim of our study was to assess the ex vivo effect of ethanolic extract of propolis (EEP) upon the activity and expression of iNOS, along with IFN-γ and IL-10 production in Algerian Celiac patients. In this context, PBMCs isolated from peripheral blood of Celiac patients and healthy controls were cultured with different concentrations of EEP. NO production was measured using the Griess method, whereas quantitation of IFN-γ and IL-10 levels was performed by ELISA. Inducible nitric oxide synthase (iNOS) expression, NFκB and pSTAT-3 activity were analyzed by immunofluorescence assay. Our results showed that PBMCs from Celiac patients produced high levels of NO and IFN-γ compared with healthy controls (HC). Interestingly, EEP reduced significantly, NO and IFN-γ levels and significantly increased IL-10 levels at a concentration of 50 µg/mL. Importantly, EEP downmodulated the iNOS expression as well as the activity of NFκB and pSTAT-3 transcription factors. Altogether, our results highlight the immunomodulatory effect of propolis on NO pathway and on pro-inflammatory cytokines. Therefore, we suggest that propolis may constitute a potential candidate to modulate inflammation during Celiac Disease and has a potential therapeutic value.

Ex vivo effects of flavonoïds extracted from Artemisia herba alba on cytokines and nitric oxide production in Algerian patients with Adamantiades-Behçet's disease.

BACKGROUND: Adamantiades-Behçet's disease (ABD) is a chronic multisystemic inflammation with unknown pathophysiology. This disorder is associated with a dysregulation of the cytokine network that hyperactivates neutrophils and macrophages. In this study, we investigate the modulatory effects of flavonoïd compounds extracted from Algerian medicinal plant Artemisia herba alba on Th1 and Th2 cytokines and nitric oxide production. METHODS: The modulatory effects of flavonoïds extracted from Artemisia herba alba on cytokines and nitric oxide production by peripheral blood mononuclear cells isolated from Algerian ABD patients and healthy controls were respectively measured by means of ELISA assays and Griess modified method. RESULTS: Our results show that flavonoïds significantly reduce the production of interleukin-12, the key effector of T helper 1 (Th1) cells and nitric oxide in a dose-dependent manner in Adamantiades-Behçet's disease. In contrast, the production of IL-4, the key marker of Th2 cells was increased. CONCLUSION: This study suggests that in vitro supplementation with flavonoïds extracted from Artemisia herba alba could have potential immuno-modulatory effects characterised by a down-regulation and up-regulation of Th1 and Th2 cytokines, respectively. Moreover, flavonoïds may prevent nitric oxide induced damages.