Stat5 opposes the transcription factor Tox and rewires exhausted CD8+ T cells toward durable effector-like states during chronic antigen exposure

Rewiring exhausted CD8+ T (Tex) cells toward functional states remains a therapeutic challenge. Tex cells are epigenetically programmed by the transcription factor Tox. However, epigenetic remodeling occurs as Tex cells transition from progenitor (Texprog) to intermediate (Texint) and terminal (Texterm) subsets, suggesting development flexibility. We examined epigenetic transitions between Tex cell subsets and revealed a reciprocally antagonistic circuit between Stat5a and Tox. Stat5 directed Texint cell formation and re-instigated partial effector biology during this Texprog-to-Texint cell transition. Constitutive Stat5a activity antagonized Tox and rewired CD8+ T cells from exhaustion to a durable effector and/or natural killer (NK)-like state with superior anti-tumor potential. Temporal induction of Stat5 activity in Tex cells using an orthogonal IL-2:IL2Rβ-pair fostered Texint cell accumulation, particularly upon PD-L1 blockade. Re-engaging Stat5 also partially reprogrammed the epigenetic landscape of exhaustion and restored polyfunctionality. These data highlight therapeutic opportunities of manipulating the IL-2-Stat5 axis to rewire Tex cells toward more durably protective states.

Signaling Through FcγRIIA and the C5a-C5aR Pathway Mediate Platelet Hyperactivation in COVID-19

Patients with COVID-19 present with a wide variety of clinical manifestations. Thromboembolic events constitute a significant cause of morbidity and mortality in patients infected with SARS-CoV-2. Severe COVID-19 has been associated with hyperinflammation and pre-existing cardiovascular disease. Platelets are important mediators and sensors of inflammation and are directly affected by cardiovascular stressors. In this report, we found that platelets from severely ill, hospitalized COVID-19 patients exhibited higher basal levels of activation measured by P-selectin surface expression and had poor functional reserve upon in vitro stimulation. To investigate this question in more detail, we developed an assay to assess the capacity of plasma from COVID-19 patients to activate platelets from healthy donors. Platelet activation was a common feature of plasma from COVID-19 patients and correlated with key measures of clinical outcome including kidney and liver injury, and APACHEIII scores. Further, we identified ferritin as a pivotal clinical marker associated with platelet hyperactivation. The COVID-19 plasma-mediated effect on control platelets was highest for patients that subsequently developed inpatient thrombotic events. Proteomic analysis of plasma from COVID-19 patients identified key mediators of inflammation and cardiovascular disease that positively correlated with in vitro platelet activation. Mechanistically, blocking the signaling of the FcγRIIa-Syk and C5a-C5aR pathways on platelets, using antibody-mediated neutralization, IgG depletion or the Syk inhibitor fostamatinib, reversed this hyperactivity driven by COVID-19 plasma and prevented platelet aggregation in endothelial microfluidic chamber conditions. These data identified these potentially actionable pathways as central for platelet activation and/or vascular complications and clinical outcomes in COVID-19 patients. In conclusion, we reveal a key role of platelet-mediated immunothrombosis in COVID-19 and identify distinct, clinically relevant, targetable signaling pathways that mediate this effect.

Abstract 2723: How BRCA1/2 mutations in TNBC affect TME and subsequently immune cell functions

Breast cancer type 1 and 2 susceptibility proteins (BRCA1/BRCA2) are well known breast cancer genes, mutations in which lead to defective homologous recombination repair (HRR). HR-based DNA repair deficiency (HRD) scores can be used to indicate DNA damage, genomic instability and may predict response to DNA damaging agents in BRCA1/2 mutated tumors. Tumors with a high HRD score caused by complete loss of BRCA1 or BRCA2 function locus-specific LOH are sensitive to DNA damage agents including platinum-based chemotherapy and poly (ADP-ribose) polymerase (PARP) inhibitors (PARPi). To understand the relationship between BRCA1/2 mutations and DNA damage in the tumor microenvironment (TME), we have characterized 107 BRCA1/2 tumors to determine HRD score using whole exome sequencing (WES) and simultaneously measured markers of DNA damage, PARP expression, tumor-infiltrating lymphocytes (TILs) and immune checkpoints to identify potential treatment targets on matching samples (n=47) using highly multiplexed fluorescence microscopy CO-Detection by indEXing (CODEX). We have established and validated a 40-plex breast cancer specific antibody panel consisting of markers to detect DNA damage, TILs and immune checkpoints to deeply profile how the TME is affected by BRCA1/2 mutations using CODEX. Computational image processing of CODEX data was performed to interrogate changes in number, size, morphology, and marker expression in tumor and immune cells. We have characterized BRCA1/2 tumors (n=47) on Tissue Microarrays (TMAs), and we have detected cytotoxic CD8+T and CD107a+NK cells in HRD low (<42) and HRD high groups. Interestingly, their frequency and cytolytic function (measured by Granzyme A and perforin transcript level) appear to be associated with HRD scores. For instance, HRD low groups showed increased cytotoxic CD8+T and CD107a+NK cells whereas HRD high groups revealed decreased cell numbers as well as cytolytic function. We observed that HRD high, LOH positive was associated with increased DNA damage marker expression in tumor cells (H3pSer28, pATM, yH2AX) as well as NK cells (pATM) whereas immune checkpoint protein levels were decreased. We have planned quantitative analysis which allow us to determine the percentage of cell subtypes as well as the spatial compartmentalization of cells to interrogate the tumor microenvironment associated with BRCA1/2 mutations. In conclusion, BRCA1/2 mutated tumors with high HRD score revealed upregulated DNA damage expression in immune cells suggesting that BRCA1/2 mutations can impact HRR in CD8+T cells and CD107a+ NK cells and subsequently affect their ability to produce Granzyme A and Perforin. Our findings will decipher the role of DNA damage in BRCA1/2 mutated tumor cells and immune cell types. Outcomes can potentially predict treatment responses such as DNA damage, PARPi and checkpoint inhibitor therapies in TNBC BRCA1/2 breast cancer.

Citation Format: Dana Pueschl, Derek A. Oldrige, Jonathan Belman, Jake S. Shilan, Anupma Nayak, Bradley Wubbenhorst, John Pluta, Robert H. Vonderheide, Michael Feldman, Kara N. Maxwell, E. John Wherry, Susan M. Domchek, Katherine L. Nathanson. How BRCA1/2 mutations in TNBC affect TME and subsequently immune cell functions [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2723.

Long-term consequences of severe closed head injury on episodic memory

This is the first systematic investigation of the very long-term effects of severe closed head injury (CHI) on objective measures of memory, and the first to employ both a normal control group and an 'other injury' control group consisting of spinal cord injury (SCI) patients. The CHI group displayed significantly poorer performance on every memory measure, and the effect sizes were large. This impairment in episodic memory is neither due to pre-injury nor post-injury differences between CHI and normal control subjects because the same differences were found when the CHI group was compared to a group of SCI patients. The findings demonstrate severe impairment in learning and retention many years after sustaining a severe CHI, which is likely in part due to the bilateral hippocampal damage shown in neuropathological studies. This life-long memory impairment needs to be addressed by community service programs.

A comparison of phonemic, semantic, and alternating word fluency in Parkinson's disease

Word fluency in 45 medicated non-demented Parkinson's disease (PD) patients and 45 normal control subjects was studied with a Phonemic Word Fluency (PWF) task using the letters F, A, and S, a Semantic Word Fluency (SWF) task using the categories animals, boys' names, and states, and an Alternating Word Fluency (AWF) task requiring the person to alternate between colors and occupations, animals and states, and words beginning with C and P. The number of words generated did not differ for trials with F, A, S, or states, but PD patients generated significantly fewer animal names and boys' names. PD patients also generated significantly fewer words on each of the three AWF trials. The PD patients scored 21% lower than the normal control group on the total AWF score, but only 10% lower for the PWF and SWF scores. The greater impairment on the AWF task which requires the use of internal attentional control to rapidly shift mental set can be considered a type of executive functioning deficit. This is consistent with the growing literature suggesting frontal systems dysfunction in PD and with the view that dopaminergic treatment only incompletely restores functioning in the frontostriatal system.

Alzheimer Disease Assessment Scale: a subtest analysis

The Alzheimer Disease Assessment Scale (ADAS) was administered to 61 Alzheimer patients, 52 elderly controls, and 80 controls between age 7 and 54 years. The Alzheimer group was categorized into different severity levels of dementia based on MMSE scores: very mild (> or = 24), mild (> or = 20), moderate (10-19), and severe (0-9). All 11 ADAS Cognitive subtest scores for the mild, moderate, and severe dementia groups were statistically worse than the elderly control group. This was also the case for the very mild group, except for Naming, Commands, Constructional Praxis, and Ideational Praxis. In terms of magnitude of effect, memory and spontaneous language items were the earliest indicators on the ADAS, while praxis, commands, and naming items were only sensitive later in the course of the disorder. The best single indicators of progression throughout the severity continuum of dementia (i.e., from normal to severe) were the Orientation subtest, the ADAS Cognitive score, and the ADAS Total score. The ADAS Noncognitive subtests generally did not show the progression with increasing dementia that was evident on the ADAS Cognitive subtest. Differences in educational level had no statistically significant effects on any of the ADAS subtest scores, and age differences were few and small in magnitude. The differential rate of decline of the various ADAS subtests appears to reflect both the changing pattern of cognitive impairments as a function of severity of DAT and also to some extent the psychometric limitations of some of the subtests.