Caspase-8 restricts natural killer cell accumulation during MCMV Infection

CASP8 Is a Potential Therapeutic Target and Is Correlated with Pyroptosis in Traumatic Brain Injury

BACKGROUND

Traumatic brain injury (TBI) is a major cause of neurological and psychological problems, especially long-term disability. The purpose of this article is to explore molecular mechanisms linking TBI and pyroptosis with the aim of providing a promising target for future therapeutic interventions.

METHODS

GSE104687 microarray dataset was downloaded from the Gene Expression Omnibus database to obtain differential expressed genes. Meanwhile, pyroptosis-related genes were screened from GeneCards database, and the overlapped genes were considered as the pyroptosis-related genes in TBI. The immune infiltration analysis was conducted to quantify lymphocyte infiltration levels. Moreover, we researched the relevant microRNAs (miRNAs) and transcription factors and investigated the interactions and functions of miRNAs. In addition, the validation set and in vivo experiment further verified the expression of hub gene.

RESULTS

Altogether, we found 240 differential expressed genes in GSE104687 and 254 pyroptosis-related genes in the GeneCards database, and the overlapped gene was caspase 8 (CASP8). Immune Infiltration Analysis suggested the abundance of Tregs cells was significantly higher in TBI group. The NKT and CD8+ Tem were positively correlated with the expression levels of CASP8. The most significant term regarding CASP8 in Reactome pathways analysis was related to NF-kappaB. A total of 20 miRNAs and 25 transcription factors associated with CASP8 were obtained. After investigating the interactions and functions of miRNAs, the NF-kappaB-related signaling pathway was still enriched with a relatively low P-value. The validation set and in vivo experiment further verified the expression of CASP8.

CONCLUSIONS

Our study showed the potential role of CASP8 in pathogenesis of TBI, which may provide a new target for individualized therapy and drug development.

Programmed Necrosis in Host Defense

Host control over infectious disease relies on the ability of cells in multicellular organisms to detect and defend against pathogens to prevent disease. Evolution affords mammals with a wide variety of independent immune mechanisms to control or eliminate invading infectious agents. Many pathogens acquire functions to deflect these immune mechanisms and promote infection. Following successful invasion of a host, cell autonomous signaling pathways drive the production of inflammatory cytokines, deployment of restriction factors and induction of cell death. Combined, these innate immune mechanisms attract dendritic cells, neutrophils and macrophages as well as innate lymphoid cells such as natural killer cells that all help control infection. Eventually, the development of adaptive pathogen-specific immunity clears infection and provides immune memory of the encounter. For obligate intracellular pathogens such as viruses, diverse cell death pathways make a pivotal contribution to early control by eliminating host cells before progeny are produced. Pro-apoptotic caspase-8 activity (along with caspase-10 in humans) executes extrinsic apoptosis, a nonlytic form of cell death triggered by TNF family death receptors (DRs). Over the past two decades, alternate extrinsic apoptosis and necroptosis outcomes have been described. Programmed necrosis, or necroptosis, occurs when receptor interacting protein kinase 3 (RIPK3) activates mixed lineage kinase-like (MLKL), causing cell leakage. Thus, activation of DRs, toll-like receptors (TLRs) or pathogen sensor Z-nucleic acid binding protein 1 (ZBP1) initiates apoptosis as well as necroptosis if not blocked by virus-encoded inhibitors. Mammalian cell death pathways are blocked by herpesvirus- and poxvirus-encoded cell death suppressors. Growing evidence has revealed the importance of Z-nucleic acid sensor, ZBP1, in the cell autonomous recognition of both DNA and RNA virus infection. This volume will explore the detente between viruses and cells to manage death machinery and avoid elimination to support dissemination within the host animal.

The Relationship of Pyroptosis-Related Genes, Patient Outcomes, and Tumor-Infiltrating Cells in Bladder Urothelial Carcinoma (BLCA)

Introduction: The role of pyroptosis and its effects on tumor-infiltrating cells (TICs) in the pathogenesis and treatment outcomes of patients with bladder urothelial carcinoma (BLCA) remains unclear.

Methods: We conducted a bioinformatics analysis on the pyroptosis-related genes (PRGs) and TICs using data from public domains, and evaluated their impact on the pathogenesis and clinical outcomes of BLCA patients. A risk score based on PRGs and a prognostic risk model that incorporated patient demographics, tumor characteristics, and differentially expressed genes (DEGs) were developed.

Results: Twenty-three DEGs of 52 PRGs were identified in BLCA and normal samples from the TCGA database. Missense mutations and single nucleotide polymorphisms in PRGs are the most common genetic abnormalities. Patients with high PRG risk scores showed an inferior survival compared to those with low risk scores. The prognostic risk model based on patient demographics, tumor characteristics, and DEGs showed good predictive values for patient survival at 1, 3, and 5 years in BLCA patients. Caspase-8 (CASP8) was the only intersection gene of the prognostic genes, DEGs, and different genes expressed in tissue. Patients with a high CASP8 expression had improved survival, and an increased CASP8 expression level was observed in activated CD4 memory T cells, follicular T helper cells, resting NK cells, M0 macrophages, and activated dendritic cells. CASP8 expression also showed a positive correlation with the IL7R expression—a key cell marker of CD4 memory T cells. CASP8 expression also showed correlations with immune checkpoints (PDCD1, CD274, and CTLA4) and response to immune checkpoint inhibitors.

Conclusion: Our data suggest that PRGs, especially CASP8, showed strong associations with patient outcomes and TICs in BLCA. If validated, these results could potentially aid in the prognostication and guide treatment in BLCA patients.