Biology subjects

Ting, A. T.

Publications and source records attributed to Ting, A. T..

3 recordsLinked to original sources

bioRxiv2025

T cells use TNF and IFNγ for paracrine killing with target discrimination programmed by pathogen-derived factors

Cytotoxic T lymphocytes (CTLs) are known to eliminate target cells through perforin-mediated, contact-dependent killing - a process limited by the number of effector T cells despite its serial nature. CTLs likely also possess a mass killing mechanism that can eliminate target cells more efficiently. Using CAR-T cells against B7H3 present on B16 tumor targets, we demonstrate that activated T cells can also kill targets in a perforin-independent manner by releasing diffusible TNF and IFN{gamma} capable of killing nearby targets in a paracrine fashion even if they bear no antigen. Against an unperturbed target, paracrine killing is inefficient but is enhanced by the deletion of TNFR1 signaling molecules such as TAK1, HOIP, or TBK1/IKK{varepsilon}. Notably, these molecules are inhibited naturally by pathogen-encoded antagonists. Expression of a microbial-encoded antagonist, such as the Yersinia-encoded YopJ that antagonizes TAK1 or Ebola-encoded VP35 that antagonizes TBK1/IKK{varepsilon}, alters the target cell response to these cytokines from non-lethal to lethal. We propose that target cells are inherently resistant to killing by TNF and IFN{gamma}, but the presence of a microbial factor alters this sensitivity, providing for the selective elimination of the infected cell while minimizing harm to uninfected bystander cells. We propose the term pathogen-restriction to describe this discriminatory mechanism. Potentially, any microbial-derived factor that crosstalks with the TNF and IFN{gamma} signaling pathways can function as a pathogen-restriction element. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=129 SRC="FIGDIR/small/696308v1_ufig1.gif" ALT="Figure 1"> View larger version (33K): org.highwire.dtl.DTLVardef@ea6418org.highwire.dtl.DTLVardef@517489org.highwire.dtl.DTLVardef@1ba0e22org.highwire.dtl.DTLVardef@1f5fef8_HPS_FORMAT_FIGEXP M_FIG C_FIG Short SummaryT cells use TNF and IFN{gamma} to kill target cells in a paracrine manner where target elimination is restricted by the presence of pathogen-derived factors.

immunology↗

bioRxiv2024

TBK1 and IKKϵ protect target cells from IFNγ-mediated T cell killing via an inflammatory apoptotic mechanism

Cytotoxic T cells produce interferon gamma (IFN{gamma}), which plays a critical role in anti-microbial and anti-tumor responses. However, it is not clear whether T cell-derived IFN{gamma} directly kills infected and tumor target cells, and how this may be regulated. Here, we report that target cell expression of the kinases TBK1 and IKK{varepsilon} regulate IFN{gamma} cytotoxicity by suppressing the ability of T cell-derived IFN{gamma} to kill target cells. In tumor targets lacking TBK1 and IKK{varepsilon}, IFN{gamma} induces expression of TNFR1 and the Z-nucleic acid sensor, ZBP1, to trigger RIPK1-dependent apoptosis, largely in a target cell-autonomous manner. Unexpectedly, IFN{gamma}, which is not known to signal to NF{kappa}B, induces hyperactivation of NF{kappa}B in TBK1 and IKK{varepsilon} double-deficient cells. TBK1 and IKK{varepsilon} suppress IKK/{beta} activity and in their absence, IFN{gamma} induces elevated NF{kappa}B-dependent expression of inflammatory chemokines and cytokines. Apoptosis is thought to be non-inflammatory, but our observations demonstrate that IFN{gamma} can induce an inflammatory form of apoptosis, and this is suppressed by TBK1 and IKK{varepsilon}. The two kinases provide a critical connection between innate and adaptive immunological responses by regulating three key responses: (1) phosphorylation of IRF3/7 to induce type I IFN; (2) inhibition of RIPK1-dependent death; and (3) inhibition of NF{kappa}B-dependent inflammation. We propose that these kinases evolved these functions such that their inhibition by pathogens attempting to block type I IFN expression would enable IFN{gamma} to trigger apoptosis accompanied by an alternative inflammatory response. Our findings show that loss of TBK1 and IKK{varepsilon} in target cells sensitizes them to inflammatory apoptosis induced by T cell-derived IFN{gamma}. Short SummaryIn the absence of TBK1 and IKK{varepsilon}, target cells are killed by T cells in an IFN{gamma}-dependent manner. In TBK1 and IKK{varepsilon}-deficient cells, IFN{gamma} induces RIPK1-dependent death, as well as hyper-induction of NF{kappa}B-dependent inflammatory genes. This suggests that any inhibition of TBK1/IKK{varepsilon} to block type I IFN expression will result in the demise of the cell accompanied by an alternate inflammatory program. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=118 SRC="FIGDIR/small/606693v1_ufig1.gif" ALT="Figure 1"> View larger version (27K): org.highwire.dtl.DTLVardef@1606b75org.highwire.dtl.DTLVardef@12eebc0org.highwire.dtl.DTLVardef@177c033org.highwire.dtl.DTLVardef@eb5819_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2020

Immune dysregulation in SHARPIN-deficient mice is dependent on CYLD-mediated cell death

SHARPIN, together with RNF31/HOIP and RBCK1/HOIL1, form the linear ubiquitin chain assembly complex (LUBAC) E3 ligase that catalyzes M1-linked poly-ubiquitination. Mutations in RNF31/HOIP and RBCK/HOIL1 in humans and Sharpin in mice lead to auto-inflammation and immunodeficiency but the mechanism underlying the immune dysregulation remains unclear. We now show that the phenotype of the Sharpin-/- mice is dependent on CYLD, the deubiquitinase that removes K63-linked poly-ubiquitin chains. The dermatitis, disrupted splenic architecture, and loss of Peyers patches in the Sharpin-/- mice were fully reversed in Sharpin-/-Cyld-/- mice. There is enhanced association of RIPK1 with the death-inducing signaling complex (DISC) following TNF stimulation in Sharpin-/- cells, and this is dependent on CYLD since it is reversed in Sharpin-/-Cyld-/- cells. Enhanced RIPK1 recruitment to the DISC in Sharpin-/- cells correlated with impaired phosphorylation of CYLD at serine 418, a modification reported to inhibit its enzymatic activity. The dermatitis in the Sharpin-/- mice was also ameliorated by the conditional deletion of Cyld using LysM-cre or Cx3cr1-cre indicating that CYLD-dependent death of myeloid cells is inflammatory. Our studies reveal that under physiological conditions, TNF- and RIPK1-dependent cell death is suppressed by the linear ubiquitin-dependent inhibition of CYLD. The Sharpin-/- phenotype illustrates the pathological consequences when CYLD inhibition fails. Short SummaryIn the absence of SHARPIN, cells fail to properly regulate the deubiquitinase CYLD, leading to RIPK1-mediated cell death. Deletion of Cyld reverses the sensitivity of Sharpin-/- cells to TNF-induced cell death, as well as the multi-organ inflammation and immune dysfunction observed in Sharpin-/- mice.

immunology↗