STING agonist promotes CAR T cell trafficking and persistence in breast cancer

CAR T therapy targeting solid tumors is restrained by limited infiltration and persistence of those cells in the tumor microenvironment (TME). Here, we developed approaches to enhance the activity of CAR T cells using an orthotopic model of locally advanced breast cancer. CAR T cells generated from Th/Tc17 cells given with the STING agonists DMXAA or cGAMP greatly enhanced tumor control, which was associated with enhanced CAR T cell persistence in the TME. Using single-cell RNA sequencing, we demonstrate that DMXAA promoted CAR T cell trafficking and persistence, supported by the generation of a chemokine milieu that promoted CAR T cell recruitment and modulation of the immunosuppressive TME through alterations in the balance of immune-stimulatory and suppressive myeloid cells. However, sustained tumor regression was accomplished only with the addition of anti-PD-1 and anti-GR-1 mAb to Th/Tc17 CAR T cell therapy given with STING agonists. This study provides new approaches to enhance adoptive T cell therapy in solid tumors

Persistent ER Stress Induces the Spliced Leader RNA Silencing Pathway (SLS), Leading to Programmed Cell Death in Trypanosoma brucei

Trypanosomes are parasites that cycle between the insect host (procyclic form) and mammalian host (bloodstream form). These parasites lack conventional transcription regulation, including factors that induce the unfolded protein response (UPR). However, they possess a stress response mechanism, the spliced leader RNA silencing (SLS) pathway. SLS elicits shut-off of spliced leader RNA (SL RNA) transcription by perturbing the binding of the transcription factor tSNAP42 to its cognate promoter, thus eliminating trans-splicing of all mRNAs. Induction of endoplasmic reticulum (ER) stress in procyclic trypanosomes elicits changes in the transcriptome similar to those induced by conventional UPR found in other eukaryotes. The mechanism of up-regulation under ER stress is dependent on differential stabilization of mRNAs. The transcriptome changes are accompanied by ER dilation and elevation in the ER chaperone, BiP. Prolonged ER stress induces SLS pathway. RNAi silencing of SEC63, a factor that participates in protein translocation across the ER membrane, or SEC61, the translocation channel, also induces SLS. Silencing of these genes or prolonged ER stress led to programmed cell death (PCD), evident by exposure of phosphatidyl serine, DNA laddering, increase in reactive oxygen species (ROS) production, increase in cytoplasmic Ca2+, and decrease in mitochondrial membrane potential, as well as typical morphological changes observed by transmission electron microscopy (TEM). ER stress response is also induced in the bloodstream form and if the stress persists it leads to SLS. We propose that prolonged ER stress induces SLS, which serves as a unique death pathway, replacing the conventional caspase-mediated PCD observed in higher eukaryotes

A critical role for donor-derived IL-22 in cutaneous chronic GVHD

Graft-versus-host disease (GVHD) is the major cause of nonrelapse morbidity and mortality after allogeneic stem cell transplantation (allo-SCT). Prevention and treatment of GVHD remain inadequate and commonly lead to end-organ dysfunction and opportunistic infection. The role of interleukin (IL)-17 and IL-22 in GVHD remains uncertain, due to an apparent lack of lineage fidelity and variable and contextually determined protective and pathogenic effects. We demonstrate that donor T cell-derived IL-22 significantly exacerbates cutaneous chronic GVHD and that IL-22 is produced by highly inflammatory donor CD4⁺ T cells posttransplantation. IL-22 and IL-17A derive from both independent and overlapping lineages, defined as T helper (Th)22 and IL-22⁺ Th17 cells. Donor Th22 and IL-22⁺ Th17 cells share a similar IL-6-dependent developmental pathway, and while Th22 cells arise independently of the IL-22⁺ Th17 lineage, IL-17 signaling to donor Th22 directly promotes their development in allo-SCT. Importantly, while both IL-22 and IL-17 mediate skin GVHD, Th17-induced chronic GVHD can be attenuated by IL-22 inhibition in preclinical systems. In the clinic, high levels of both IL-17A and IL-22 expression are present in the skin of patients with GVHD after allo-SCT. Together, these data demonstrate a key role for donor-derived IL-22 in patients with chronic skin GVHD and confirm parallel but symbiotic developmental pathways of Th22 and Th17 differentiation.Kate H. Gartlan, Hemamalini Bommiasamy, Katelyn Paz, Andrew N. Wilkinson, Mary Owen, Dawn K. Reichenbach, Tatjana Banovic, Kimberly Wehner, Faith Buchanan, Antiopi Varelias, Rachel D. Kuns, Karshing Chang, Yuri Fedoriw, Thomas Shea, James Coghill, Michael Zaiken, Maximilian W. Plank, Paul S. Foster, Andrew D. Clouston, Bruce R. Blazar, Jonathan S. Serody, Geoffrey R. Hil