Blog – Page 5

If cancer’s genetic off switch is found then even Covid 19s off switch could essentially be found aswell.

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Gene expression, where cells use the genetic information encoded in DNA to produce proteins, has been thought of as a dimmer light.

How much a particular gene gets expressed continually rises and falls, depending on the needs of a cell at any given time. It’s like adjusting the lighting of a room until it’s just right for your mood.

But University at Buffalo researchers have shown that a considerable portion of a human’s roughly 20,000 genes express more like your standard light switch — fully on or fully off.

Dominic P. Golec, Pamela L. Schwartzberg and colleagues (National Institute of Allergy and Infectious Diseases (NIAID)) describe a PI3 Kinase-Foxo1-FasL signaling circuit that promotes amplified signaling and rewires transcriptional and epigenetic programs driving IFN-γ and altered T helper cell differentiation in CD4+ T cells from mice expressing an activating mutant of phosphoinositide 3-kinase delta.

Immunodeficiency LymphocyteBiology

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While inputs regulating CD4⁺ T helper (Th) cell differentiation are well defined, the integration of downstream signaling with transcriptional and epigenetic programs that define Th lineage identity remains incompletely resolved. PI3K signaling is a critical regulator of T cell function; activating mutations affecting PI3Kδ result in an immunodeficiency with multiple T cell defects. Using mice expressing activated PI3Kδ, we found aberrant expression of proinflammatory Th1 signature genes under Th2-inducing conditions, both in vivo and in vitro. This dysregulation was driven by a PI3Kδ-IL-2-Foxo1 signaling amplification loop, fueling Foxo1 inactivation, loss of Th2 lineage restriction, and extensive epigenetic reprogramming. Surprisingly, ablation of Fasl, a Foxo1-repressed gene, normalized both Th2 differentiation and TCR signaling. BioID and imaging revealed Fas interactions with TCR signaling components, which were supported by Fas-mediated potentiation of TCR signaling that could occur in the absence of FADD. Our results highlight Fas-FasL signaling as a critical intermediate in phenotypes driven by activated PI3Kδ, thereby linking two key pathways of immune dysregulation.

Kathrynne Warrick, Chandrashekhar Pasare et al. show that PD-1 blockade leads to de novo priming of self-reactive CD8 T cells resulting in immune related adverse events.

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Immune checkpoint inhibitors (ICIs) improve cancer survival but can trigger immune-related adverse events. Among these, fulminant myocarditis is an often fatal complication with limited therapies. We developed a mouse model employing cardiomyocyte-restricted antigen expression to define how ICIs drive cardiac autoimmunity. Combined cytotoxic T cell antigen-4 (αCTLA-4) and programmed death-1 (αPD-1) blockade uniquely induced robust expansion of antigen-specific CD8 T cells, myocardial inflammation, and lethal arrhythmias. PD-1 blockade alone permitted the priming and effector differentiation of naive autoreactive CD8 T cells, whereas concomitant CTLA-4 inhibition amplified cardiac pathology. Unexpectedly, myocardial injury was independent of perforin-mediated cytotoxicity but critically depended on T cell–derived TNF, which promoted myeloid recruitment, cytokine production, and arrhythmogenesis. Genetic ablation of CD8 T cell–derived tumor necrosis factor (TNF) or TNF receptor 2 (TNFR2) blockade prevented cardiotoxicity while preserving antitumor efficacy. These findings establish a TNF-TNFR2–driven inflammatory circuit downstream of autoreactive CD8 T cells as a central mechanism of ICI myocarditis and a strategy to uncouple cardiotoxicity from immunotherapy benefits.