Manipulating DNA damage-response signaling for the treatment of immune-mediated diseases

Abstract

Antigen-activated lymphocytes undergo extraordinarily rapid cell division in the course of immune responses. We hypothesized that this unique aspect of lymphocyte biology leads to unusual genomic stress in recently antigen-activated lymphocytes and that targeted manipulation of DNA damage-response (DDR) signaling pathways would allow for selective therapeutic targeting of pathological T cells in disease contexts. Consistent with these hypotheses, we found that activated mouse and human T cells display a pronounced DDR in vitro and in vivo. Upon screening a variety of small-molecule compounds, we found that potentiation of p53 (via inhibition of MDM2) or impairment of cell cycle checkpoints (via inhibition of CHK1/2 or WEE1) led to the selective elimination of activated, pathological T cells in vivo. The combination of these strategies [which we termed "p53 potentiation with checkpoint abrogation" (PPCA)] displayed therapeutic benefits in preclinical disease models of hemophagocytic lymphohistiocytosis and multiple sclerosis, which are driven by foreign antigens or self-antigens, respectively. PPCA therapy targeted pathological T cells but did not compromise naive, regulatory, or quiescent memory T-cell pools, and had a modest nonimmune toxicity profile. Thus, PPCA is a therapeutic modality for selective, antigen-specific immune modulation with significant translational potential for diverse immune-mediated diseases.autoimmunity | immune regulation | DNA damage response | therapeutics T he immune system has evolved under intense pressure from pathogens that proliferate very rapidly (1). In responding to infections, the adaptive immune system needs to mobilize rare pathogen-specific lymphocytes quickly. This mobilization is achieved by rapid, exponential expansion of responding lymphocyte clones. Indeed, antigen-activated T and B cells appear to have some of the most rapid division rates among all mammalian cell types (2). We hypothesized that this unique aspect of lymphocyte biology would cause significant genomic stress in responding lymphocytes and that novel forms of therapeutic immune suppression could be developed by exploiting this weakness. Such strategies would allow for "developmental" or "kinetic" targeting of pathological immune responses at the time of disease activity or organ rejection and could complement or replace chronic suppression of immune signaling or cytokine pathways. The recent preclinical and clinical development of a wide array of rationally designed small-molecule inhibitors of various signaling and effector molecules within DNA damage-response (DDR) cascades has provided an opportunity to test this hypothesis (3, 4).We first looked for evidence of a DDR occurring in activated T cells in physiological contexts and found a broad DDR in murine and human T cells. Next, upon screening an array of DNA-damaging agents and DDR-altering small molecules for their ability to kill activated, but not resting, T cells, we identified two promising strategies. We found that inhibition of MDM2 (an end...

ATR kinase inhibitor AZD6738 potentiates CD8+ T cell–dependent antitumor activity following radiation

“…AZD6738 is an ATP-competitive, orally bioavailable pharmaceutical that inhibits ATR kinase activity with an IC 50 of 0.001 μM in vitro, while showing no significant inhibition of 442 other kinases at 1 μM (34,37). AZD6738 has a significantly higher IC 50 against PI3Ks in vitro (IC 50 6.8 μM against PI3Kδ and >50 μM against PI3Kα, PI3Kβ, and PI3Kγ; unpublished observations). In jci.org…”

“…Volume 128 Number 9 September 2018 strated that activated CD8 + T cells are more susceptible to killing by WEE1 and Chk1/2 inhibition, although the effects were more substantial in vitro than in vivo (50). As Chk1 is a direct target of ATR, it may be that AZD6738 selectively kills recently activated, and still rapidly dividing, CD8 + T cells.…”

DNA Damage Response and Oxidative Stress in Systemic Autoimmunity

“…Although these approaches have been extensively studied in cancer, promising results have also been revealed in preclinical mouse models of autoimmunity. Therapeutic targeting of T lymphocytes from autoimmune disease patients with DDR/R inhibitors is based on their high proliferation rate and accumulation of DNA damage [150]. Indeed, in mice with experimental autoimmune encephalitis, the combination of p53 activators and CHK1/2 inhibitors led to the elimination of pathogenic, activated T lymphocytes with no side-toxicity of normal T cells.…”

Type I IFN Drives Experimental Systemic Lupus Erythematosus by Distinct Mechanisms in CD4 T Cells and B Cells

“…4C). A comparable percentage of WT and IFNAR CD4 bm12 T cells also expressed phospho-g H2AX (pgH2AX), a well-characterized marker for the DNA damage response, shown to be highly elevated in in vivo activated and proliferating T cells (36).…”