TRAF6 is required for BLyS-mediated NF-κB signaling in multiple myeloma cells

Molecular cloning and functional analysis of TRAF6 from Yangzhou great white goose Anser anser

TNF receptor-associated factor 6 (TRAF6) is an adaptor protein and an E3 ubiquitin ligase mediating multiple cell signaling pathway activation in a context-dependent manner. TRAF6 plays critical roles in innate immune response and regulates function of antigen-presenting cells. Here, we cloned the goose TRAF6 (goTRAF6) gene from a healthy Yangzhou great white goose (Anser anser), which had a typical TRAF structure and shared a high-sequence identity with TRAF6 of other birds. Quantitative real-time PCR revealed that goTRAF6 mRNA was broadly expressed in all the studied tissues, with highest expression in the heart and pectoral muscle. Overexpression of goTRAF6 caused NF-κB activation in a dose-dependent manner and substantially upregulated IFN-β expression in HEK293T cells. Following Toll-like receptor (TLR) ligand stimulation of goose peripheral blood mononuclear cells, goTRAF6 and downstream inflammatory cytokine mRNA levels considerably up-regulated, especially at early stages. Salmonella Enteritidis challenge caused overexpression of goTRAF6 and cytokine mRNA in all the examined organs. These findings demonstrated that goTRAF6 played a substantial role in TLR-TRAF6 signaling cascade, and further contributed to the antibacterial-responses in host.

IL-17A Increases Multiple Myeloma Cell Viability by Positively Regulating Syk Expression

PURPOSE: Elevated IL-17 produced by T_h17 cells was reported to promote myeloma cell growth and inhibit immune function in multiple myeloma (MM). IL-17A was also reported to promote MM growth through IL-17 receptors and enhance adhesion to bone marrow stromal cells (BMSCs). Spleen tyrosine kinase (Syk) influences MM cell survival and migration. Herein we aimed to investigate whether Syk was involved in the regulative role of IL-17A in the viability of MM cells. METHODS: Cell viability was determined using CCK8 assay. The production of cytokine including IL-17A was evaluated with ELISA. Western blotting assay was used to determine protein expression levels of Syk and nuclear factor κB (NF-κB) related molecules. mRNA expression level of RORγt was detected with reverse transcription quantitative polymerase chain reaction. RESULTS: IL-17Awas highly expressed in MM patients and was able to induce MM cell viability. Following analysis indicated that the effects of IL-17A were mediated by Syk/ nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling pathway. Immunoprecipitation also indicated that Syk is involved in IL-17A–induced Act1-TRAF6 complex formation and TRAF6 polyubiquitination in MM cells. CONCLUSIONS: Taken together, our study indicated that IL-17A increases MM cell viability through activating NF-κB signal pathway via positively regulating Syk expression. Syk also participates in the formation of IL-17R-proximal signaling complex (IL-17R-Act1-TRAF6), which is essential for IL-17A–mediated NF-kB activation. These investigations highlight that inhibition of Syk may be a potential therapeutic option for neoplastic diseases such as MM.

Targeting the cross-talk between the hedgehog and NF-κB signaling pathways in multiple myeloma

Multiple myeloma (MM) is an incurable plasma cell malignancy. Aberrant activation of the Hedgehog (Hh) and NF-κB signaling pathways is observed in MM and plays a pivotal role in the development of MM by promoting myeloma cell growth, survival, and drug resistance. In this study, we found that the Sonic Hh (SHh) ligand in the bone marrow microenvironment is responsible for the enhancement of NF-κB activity in MM cell lines NCI-H929 and U266. Notably, we discovered that Hh signaling regulates NF-κB through its classical pathway (SHh/PTCH1/SMO/GLI1) in MM cells. Meanwhile, non-classical pathway by SMO recruitment of TRAF6 to ubiquitination is also involved in it. Moreover, the SMO inhibitor cyclopamine enhances the cytotoxic effects of bortezomib in MM cell lines. Our study reveals the cross-talk between Hh members and the NF-κB pathway in the myeloma cells and provides a theoretical basis for combined utilization of Hh members and proteasome inhibition in MM.

Role of interleukin-23 in monocyte-derived dendritic cells of HBV-related acute-on-chronic liver failure and its correlation with the severity of liver damage

BACKGROUND

The role of interleukin-23 (IL-23) in monocyte-derived dendritic cells (MoDCs) from hepatitis B virus-related acute-on-chronic liver failure (HBV-ACLF) patients remains unclear. The aim of this study was to observe the correlation between the activation of the IL-23 signaling pathway and the prognosis of HBV-ACLF patients.

MATERIALS AND METHODS

The baseline levels of serum IL-6, IL-12, IL-17, IL-23, tumor necrosis factor-α (TNF-α), and interferon-γ (IFN-γ) from immune tolerant (IT), chronic hepatitis B (CHB), HBV-ACLF patients and healthy individuals who served as healthy controls (HCs) were analyzed using the Luminex system, whereas serum IL-23 from HBV-ACLF patients was measured by ELISA before and after treatment. Purified monocytes were isolated from peripheral blood and were induced into MoDCs, IL-23, IL-23R, NF-κB and TRAF6 expression in MoDCs from 4 groups was analyzed using real-time PCR, and IL-23R and intracellular IL-23 were evaluated by flow cytometry.

RESULTS

Serum IL-6, IL-12, IL-17, IL-23 and TNF-α levels were upregulated in HBV-ACLF patients compared with IT patients, CHB patients and HCs (P<0.05 for all). Serum IL-23 was closely correlated with elevated serum IL-17 in HBV-ACLF patients (r=0.5935, P<0.0001). Moreover, IL-23 and IL-23R levels were significantly upregulated in MoDCs from patients with CHB or HBV-ACLF compared with HCs, and further upregulation of IL-23 and IL-23R was observed in HBV-ACLF patients compared to CHB patients (P<0.05 for all). IL-23 expression was markedly enhanced and was correlated with elevated NF-κB and TRAF6 in MoDCs from HBV-ACLF patients (P<0.05 for both). Linear correlation analysis demonstrated significant correlations between the expression of IL-23 and disease severity markers (MELD scoring system, international normalized ratio, prothrombin time and total bilirubin, r=0.6874, r=0.6475, r=0.6249, r=0.3771, respectively, P<0.05 for all) for individual HBV-ACLF patients, and IL-23 levels were significantly upregulated in non-survival HBV-ACLF patients compared with survival HBV-ACLF patients (P<0.05).

CONCLUSION

IL-23 in serum and MoDCs is significantly elevated in HBV-ACLF patients, TRAF6/NF-κB may play a role in IL-23 production by MoDCs in HBV-ACLF patients and high pre-treatment IL-23 levels in MoDCs are associated with mortality in HBV-ACLF patients.