No abstract

Cytotoxic CD8(+) T lymphocytes (CTLs) play an important role in antiviral immunity. Several human HLA-A*0201 restricted CTL epitopes of severe acute respiratory syndrome (SARS) spike (S) protein have been identified in HLA-A*0201 transgenic (Tg) mice, but the mechanisms and properties of immune responses are still not well understood. In this study, HLA-A*0201 Tg mice were primed intramuscularly with SARS S DNA and boosted subcutaneously with HLA-A*0201 restricted peptides. The lymphocytes from draining lymph nodes, spleens and lungs were stimulated with the cognate peptides. Three different methods (ELISA, ELISPOT and FACS) were used to evaluate the immune responses during short and long periods of time after immunization. Results showed that peptide-specific CD8(+) T cells secreted IFN-γ, TNF-α and IL-2 and expressed CD107a/b on cell surface. IFN-γ(+)CD8(+) T cells and CD107a/b(+)CD8(+) T cells distributed throughout the lymphoid and non-lymphoid tissues, but the frequency of peptide-specific CD8(+) T cells was higher in lungs than in spleens and lymph nodes. The phenotype of the CD8(+) T cells was characterized based on the expression of IFN-γ. Most of the HLA-A*0201 restricted peptide-specific CD8(+) T cells represented a memory subset with CD45RB(high) and CD62L(low). Taken together, these data demonstrate that immunization with SARS S DNA and HLA-A*0201 restricted peptides can elicit antigen-specific CD8(+) T cell immune responses which may have a significant implication in the long-term protection. We provide novel information in cellular immune responses of SARS S antigen-specific CD8(+) T cells, which are important in the development of vaccine against SARS-CoV infection.

Background & Aims: Liver cancer stem cells (LCSCs) mediate therapeutic resistance and correlate with poor outcomes in patients with hepatocellular carcinoma (HCC). Fibroblast growth factor (FGF)-19 is a crucial oncogenic driver gene in HCC and correlates with poor prognosis. However, whether FGF19 signaling regulates the self-renewal of LCSCs is unknown. Methods: LCSCs were enriched by serum-free suspension. Self-renewal of LCSCs were characterized by sphere formation assay, clonogenicity assay, sorafenib resistance assay and tumorigenic potential assays. Ca 2+ image was employed to determine the intracellular concentration of Ca 2+ . Gain- and loss-of function studies were applied to explore the role of FGF19 signaling in the self-renewal of LCSCs. Results: FGF19 was up-regulated in LCSCs, and positively correlated with certain self-renewal related genes in HCC. Silencing FGF19 suppressed self-renewal of LCSCs, whereas overexpressing FGF19 facilitated CSCs-like properties via activation of FGF receptor (FGFR)-4 in none-LCSCs. Mechanistically, FGF19/FGFR4 signaling stimulated store-operated Ca 2+ entry (SOCE) through both the PLCγ and ERK1/2 pathways. Subsequently, SOCE-calcineurin signaling promoted the activation and translocation of nuclear factors of activated T cells (NFAT)-c2, which transcriptionally activated the expression of stemness-related genes ( e.g., NANOG , OCT4 and SOX2 ), as well as FGF19 . Furthermore, blockade of FGF19/FGFR4-NFATc2 signaling observably suppressed the self-renewal of LCSCs. Conclusions: FGF19/FGFR4 axis promotes the self-renewal of LCSCs via activating SOCE/NFATc2 pathway; in turn, NFATc2 transcriptionally activates FGF19 expression. Targeting this signaling circuit represents a potential strategy for improving the therapeutic efficacy of HCC.

BackgroundClonorchis sinensis (C. sinensis, Cs) is a trematode parasite that often causes chronic cumulative infections in the hepatobiliary ducts of the host and can lead to pathological changes by continuously released excretory/secretory proteins (ESPs). A T2 ribonuclease in trematode ESPs, has been identified as a potent regulator of dendritic cell (DCs) modulation. We wondered whether there was a counterpart present in CsESPs with similar activity. To gain a better understanding of CsESPs associated immune responses, we identified and characterized RNASET2 of C. sinensis (CsRNASET2) in this paper.MethodsWe expressed CsRNASET2 in Pichia pastoris and identified its molecular characteristics using bioinformatic analysis and experimental approaches. The immune modulation activities of CsRNASET2 were confirmed by evaluating cytokine production and surface markers of recombinant CsRNASET2 (rCsRNASET2) co-cultured DCs, and monitoring levels of IgG isotypes from rCsRNASET2 administered BALB/c mice.ResultsCsRNASET2 appeared to be a glycoprotein of T2 ribonuclease family harboring conserved CAS motifs and rich in B-cell epitopes. Furthermore, CsRNASET2 was present in CsESPs and was able to modulate cytokine production of DCs. In addition, rCsRNASET2 could significantly suppress the expression of lipopolysaccharide-induced DCs maturation markers. In addition, when subcutaneously administered with rCsRNASET2 there was a marked effect on IgG isotypes in mouse sera.ConclusionCollectively, we revealed that CsRNASET2, a T2 ribonuclease present in CsESPs, could modulate DCs maturation and might play an important role in C. sinensis associated immune regulation in the host.