Lower activation-induced T-cell apoptosis is related to the pathological immune response in secondary infection with hetero-serotype dengue virus

Mutant KRAS-activated circATXN7 fosters tumor immunoescape by sensitizing tumor-specific T cells to activation-induced cell death

Mutant KRAS (KRASMUT) is often exploited by cancers to shape tumor immunity, but the underlying mechanisms are not fully understood. Here we report that tumor-specific cytotoxic T lymphocytes (CTLs) from KRASMUT cancers are sensitive to activation-induced cell death (AICD). circATXN7, an NF-κB-interacting circular RNA, governs T cell sensitivity to AICD by inactivating NF-κB. Mechanistically, histone lactylation derived from KRASMUT tumor cell-produced lactic acid directly activates transcription of circATXN7, which binds to NF-κB p65 subunit and masks the p65 nuclear localization signal motif, thereby sequestering it in the cytoplasm. Clinically, circATXN7 upregulation in tumor-specific CTLs correlates with adverse clinical outcomes and immunotherapeutic resistance. Genetic ablation of circAtxn7 in CD8+ T cells leads to mutant-selective tumor inhibition, while also increases anti-PD1 efficacy in multiple tumor models in female mice. Furthermore, targeting circATXN7 in adoptively transferred tumor-reactive CTLs improves their antitumor activities. These findings provide insight into how lymphocyte-expressed circRNAs contribute to T-cell fate decisions and anticancer immunotherapies.

Emergence of Dengue 4 as Dominant Serotype During 2017 Outbreak in South India and Associated Cytokine Expression Profile

Dengue virus (DENV) infection is prevalent in tropical and subtropical regions of the world, which is fatal if untreated symptomatically. Emergence of new genotype within serotypes led to enhanced severity. The objective of the study is to identify the molecular characteristics of the DENV circulated during 2017 outbreak in Tamil Nadu, India, and to investigate the role of inflammatory cytokines in different “serotypes” and in “dengue severity”. A total of 135 suspected samples were tested for DENV infection using IgM, IgG, and qPCR assay; where 76 samples were positive for DENV and analyzed for 12 inflammatory cytokines using ELISA. Serotyping shows 14 DENV-1, 22 DENV-2, 7 DENV-3, and 33 DENV-4, where DENV-4 was predominant. Among 76, 42 isolates were successfully sequenced for C-prM region and grouped. A lineage shift was observed in DENV-4 genotype. Irrespective of serotypes, IFNγ was significantly elevated in all serotypes than control as well as in primary infection than secondary, indicating its role in immune response. GM-CSF and IP-10 were significantly elevated in secondary infection and could be used as prognostic biomarkers for secondary infection. Our observation shows differential cytokine expression profile varied with each serotype, indicating serotype/genotype-specific viral proteins might play a major role in dengue severity. DENV-4 as dominant serotype was reported in Tamil Nadu for the first time during an outbreak with a mixed Th1/Th17 cytokine expression profile that correlated with disease severity. We conclude it is essential to identify circulating viral genotype and their fitness by mutational analysis to correlate with disease severity and immune status, as this correlation will be helpful in diagnostics and therapeutics applications.

Highlights for Dengue Immunopathogenesis: Antibody-Dependent Enhancement, Cytokine Storm, and Beyond

Infection with dengue virus (DENV) can lead to a wide spectrum of clinical presentations, ranging from asymptomatic infection to death. It is estimated that the disease manifests only in 90 million cases out of the total 390 million yearly infections. Even though research has not yet elucidated which are the precise pathophysiological mechanisms that trigger severe forms of dengue, the infection elicits a critical immune response significant for dengue pathogenesis development. Understanding how the immune response to DENV is established and how it can resolve the infection or turn into an immunopathology is of great importance in DENV research. Currently, studies have extensively debated 2 hypotheses involving immune response: antibody-dependent enhancement and cytokine storm. However, despite its undeniable importance in severe forms of the disease, these 2 hypotheses are based on a primed immune status resulting from previous heterologous infection, abstaining them from explaining the severe forms of dengue in naive immune subjects, for example. Thus, it seems that a more intricate arrangement of causes and conditions must be achieved to severe dengue to occur. Among them, the cytokine network signature elicited, in association with viral aspects deserves special attention regarding the establishment of infection and evolution to pathogenesis. In this work, we intend to shed light on how those elements contribute to severe dengue development.