Broad-Based Influenza-Specific CD8+ T Cell Response without the Typical Immunodominance Hierarchy and Its Potential Implication.

Syngeneic murine systems have pre-fixed MHC, making them an imperfect model for investigating the impact of MHC polymorphism on immunodominance in influenza A virus (IAV) infections. To date, there are few studies focusing on MHC allelic differences and its impact on immunodominance even though it is well documented that an individual's HLA plays a significant role in determining immunodominance hierarchy. Here, we describe a broad-based CD8+ T cell response in a healthy individual to IAV infection rather than a typical immunodominance hierarchy. We used a systematic antigen screen approach combined with epitope prediction to study such a broad CD8+ T cell response to IAV infection. We show CD8+ T cell responses to nine IAV proteins and identify their minimal epitope sequences. These epitopes are restricted to HLA-B*44:03, HLA-A*24:02 and HLA-A*33:03 and seven out of the nine epitopes are novel (NP319-330# (known and demonstrated minimal epitope positions are subscripted; otherwise, amino acid positions are shown as normal text (for example NP 319-330 or NP 313-330)), M1124-134, M27-15, NA337-346, PB239-49, HA445-453 and NS1195-203). Additionally, most of these novel epitopes are highly conserved among H1N1 and H3N2 strains that circulated in Australia and other parts of the world.

HMGA1 promotes gastric cancer growth and metastasis by transactivating SUZ12 and CCDC43 expression.

HMGA1 protein is an architectural transcription factor that has been implicated in the progression of multiple malignant tumors. However, the role of HMGA1 in the growth and metastasis of gastric cancer (GC) has not yet been elucidated. Here, we show that HMGA1 is overexpressed in GC cells and the high expression of HMGA1 was correlated with worse survival in GC patients using a bioinformatics assay. Functionally, HMGA1 affected the EdU incorporation, colony formation, migration and invasion of GC cells by exogenously increasing or decreasing the expression of HMGA1. Mechanistically, HMGA1 directly bound to the SUZ12 and CCDC43 promoter and transactivated its expression in GC cells. Inhibition of SUZ12 and CCDC43 attenuated the proliferation, migration and invasiveness of HMGA1-overexpressing GC cells in vitro. Moreover, both HMGA1 and SUZ12/CCDC43 were highly expressed in cancer cells but not in normal gastric tissues, and their expressions were positively correlated. Finally, a tail vein metastatic assay showed that HMGA1 promoted SUZ12/CCDC43-mediated GC cell metastasis in vivo. Our findings suggest that HMGA1 promotes GC growth and metastasis by transactivating SUZ12 and CCDC43 expression, highlighting HMGA1 as a potential prognostic biomarker in the treatment of GC.

FACS isolation of low percentage human antigen-specific CD8+ T cells based on activation-induced CD3 and CD8 downregulation.

As T cell activation leads to downregulation of T cell receptor (TCR) and coreceptor CD8, we developed a novel FACS-based sorting method to enrich activated antigen-specific CD8+ T cells. Using multiple established or low percentage T cell cultures, with either single antigen specificity or multiple influenza A virus antigen specificities, we have optimized the sorting method for T cell activation time and stimulating antigen dose. We have also sorted various numbers of antigen-specific CD8+ T cells into 96-well plates to demonstrate these T cells are capable of expanding into nearly pure CD8+ T cell lines. Our approach has the advantage of sorting antigen-specific T cells without knowing their specific antigenic epitopes or restricting HLA. We believe this method can be very helpful for successfully establishing CD8+ T cell lines for various purpose, including immunotherapy.

Broad-Based CD4+ T Cell Responses to Influenza A Virus in a Healthy Individual Who Lacks Typical Immunodominance Hierarchy.

Influenza A virus (IAV) infection is a significant cause of morbidity and mortality worldwide. CD4+ T cell responses have been shown to be important for influenza protection in mouse models and in human volunteers. IAV antigen-specific CD4+ T cell responses were found to focus on matrix 1 (M1) and nucleoprotein (NP) at the protein antigen level. At the epitope level, only several epitopes within M1 and NP were recognized by CD4+ T cells. And the epitope-specific CD4+ T cell responses showed a typical immunodominance hierarchy in most of the healthy individuals studied. In this study, we reported one case of atypical immunodominance hierarchy of CD4+ T cell responses to IAV. M1 and NP were still the immunodominant targets of CD4+ T cell responses. However, CD4+ T cell responses specific to 11 epitopes derived from M1 and NP were detected and showed no significant immunodominance hierarchy. Such an atypical pattern is likely determined by the individual's HLA alleles. These findings will help us better understand the anti-IAV immunity as a whole and improve future vaccines against IAV.

N-acetylglucosaminyltransferase V modulates radiosensitivity and migration of small cell lung cancer through epithelial-mesenchymal transition.

N-acetylglucosaminyltransferase V (Gnt-V) has been linked to the migration of various human cancers. Recently we have found that inhibition of Gnt-V increases the radiosensitivity of cancer cells. However, the mechanisms by which Gnt-V mediates radiosensitivity and migration, especially in small cell lung cancer (SCLC) remain unknown. In our study, two SCLC cell lines (H1688 and H146) were used to investigate whether Gnt-V modulated the radiosensitivity and migration of SCLC cells through the epithelial-mesenchymal transition (EMT). The results showed that the expression of Gnt-V correlated with the N stage in patients with SCLC. Overexpression of Gnt-V led to a further increase in the relative viable cell number and survival fraction with a decrease in apoptosis rate and Bax/Bcl-2 ratio, when the cells were treated with irradiation. By contrast, knockdown of Gnt-V with irradiation resulted in a further decrease in the relative viable cell number and survival fraction but an increase in apoptosis rate and Bax/Bcl-2 ratio. Cells expressing high levels of Gnt-V increased migration whereas low levels of Gnt-V suppressed cell migration. Besides, the transient knockdown of ZEB2 led to an increase in radiosensitivity and an inhibition in the migration of SCLC cells. Furthermore, Gnt-V was negatively correlated with E-cadherin expression but positively correlated with N-cadherin, vimentin and ZEB2 expression. Finally, an in vivo study revealed that upregulation of Gnt-V caused tumour growth more quickly, as well as the expression of EMT-related markers (N-cadherin, vimentin and ZEB2). Taken together, the study suggested that an elevation of Gnt-V could lead to the radiosensitivity and migration of SCLC cells by inducing EMT, thereby highlighting Gnt-V as a potential therapeutic target for the prevention of EMT-associated tumour radioresistance and migration.