Posted on October 3, 2021
Shown are the MFI ratios of SFN treated to untreated samples (= 3; mean; SE; *< 0
Shown are the MFI ratios of SFN treated to untreated samples (= 3; mean; SE; *< 0.05, **< 0.01, ***< 0.001). protein oxidation was STAT3, a transcription factor involved in the regulation of TH17-related genes. Accordingly, SFN significantly inhibited the activation of untransformed human T-cells derived from healthy donors or RA patients, and downregulated the expression of the transcription factor RORt, and the TH17-related cytokines IL-17A, IL-17F, and IL-22, which play a major role within the pathophysiology of many chronic inflammatory/autoimmune diseases. The inhibitory effects of SFN could be abolished by exogenously supplied GSH and by the GSH replenishing antioxidant N-acetylcysteine (NAC). Together, our study provides mechanistic insights into the mode of action of the natural substance SFN. It specifically exerts TH17 prone immunosuppressive effects on untransformed human T-cells by decreasing GSH and accumulation of ROS. Thus, SFN may offer novel clinical options for the treatment of TH17 related chronic inflammatory/autoimmune diseases such as rheumatoid arthritis. (1C3). Reactive oxygen species (ROS) promote tumor development and progression, which was the rationale of the hypothesis that this ROS-detoxification process induced by SFN might be useful as an adjuvant during anti-cancer therapy. In several phase I and II clinical trials, the therapeutic benefit of SFN has been evaluated for healthy individuals and malignancy patients (4, 5). However, GF 109203X a beneficial effect for malignancy patients could not be documented in these studies. One possible explanation that has been discussed is a limited SFN concentration or pharmacokinetics in the patients (5). It is also known that this control of tumors is usually highly dependent on the immune system. Thus, if immune cells would be inhibited by SFN, this immunosuppression could outweigh the anti-tumor effects. However, Mouse monoclonal to BID effects of SFN around the immune system of cancer patients were not considered. Recently, some studies have provided first suggestions that SFN is indeed able to modulate the immune system. Kumar et al. exhibited that the development of human myeloid-derived suppressor cells (MDSCs) from CD14+ monocytes cultured in glioma conditioned medium was inhibited by SFN, which may enhance T-cell proliferation (6). On the other hand, the study by Pal et al. suggested that effects induced by SFN eventually shifted human monocyte polarization to a direction specific to M2 macrophages, promoting an anti-inflammatory phenotype (7). Geisel et al. reported that in a murine system, SFN led to diminished IL-12 and IL-23 expression by dendritic cells (DCs) eventually interfering with pro-inflammatory immune responses (8). Yet, a direct effect of SFN on mouse T-cells was not observed. In line with these latter findings, SFN was found to ameliorate murine experimental arthritis (9) and experimental autoimmune encephalomyelitis (EAE) (8, 10). In contrast to the murine system, SFN also seemed to have GF 109203X a direct inhibitory effect on synovial T-cells derived from rheumatoid arthritis (RA) patients (9). However, the effect of SFN on main human T-cells from healthy donors was so far not investigated. Given enormous species differences, this aspect is critical for estimating its potential clinical effects. The molecular theory of how SFN acts in different cell types is as yet only partly understood. Nuclear factor erythroid 2 (NFE2)-related factor 2 (NRF-2) was identified as GF 109203X one target of SFN in murine lymphocytes, murine DCs and malignancy cells (11C13). NRF-2 is usually a leucine-zipper protein that is activated by oxidative stress and induces transcription of genes coding for anti oxidant proteins. Consistent with this, SFN treatment has been shown to boost the ROS-scavenger glutathione (GSH) in murine DCs, and also to result in high expression of the antioxidant protein heme oxygenase-1 (HO-1) (12). In contrast, another study using murine spleen lymphocytes demonstrated that 20 M SFN rather increased the basal levels of intracellular ROS in murine spleen lymphocytes (11). Taken together, the existing data produce a confusing picture of the effects of SFN around the intracellular redox homeostasis, which might be due to the different systems used, i.e., murine vs. human cells, adaptive vs. GF 109203X innate immune cells or tumor cells vs. main cells. However, an exact knowledge of the SFN effect on the redox-regulation in human T-cells is crucial to estimate its clinical relevance in T-cell related diseases, since the redox balance strongly modulates T-cell functions (14). In this regards, we have shown earlier that reducing conditions favor activation of main human T-cells (15), whereas oxidative stress prospects to hyporesponsiveness or even cell death of primary human T-cells (16, 17). In line with these findings, it has recently been postulated that low ROS levels in RA individual derived T-cells connects cellular metabolism with auto-aggressive T-cell immunity including.