Blood immunophenotyping identifies distinct kidney histopathology and outcomes in patients with lupus nephritis

Lupus nephritis (LN) is a frequent manifestation of systemic lupus erythematosus, and fewer than half of patients achieve complete renal response with standard immunosuppressants. Identifying non-invasive, blood-based pathologic immune alterations associated with renal injury could aid therapeutic decisions. Here, we used mass cytometry immunophenotyping of peripheral blood mononuclear cells in 145 patients with biopsy-proven LN and 40 healthy controls to evaluate the heterogeneity of immune activation in patients with LN and to identify correlates of renal parameters and treatment response. Unbiased analysis identified 3 immunologically distinct groups of patients with LN that were associated with different patterns of histopathology, renal cell infiltrates, urine proteomic profiles, and treatment response at one year. Patients with enriched circulating granzyme B+ T cells at baseline showed more severe disease and increased numbers of activated CD8 T cells in the kidney, yet they had the highest likelihood of treatment response. A second group characterized primarily by a high type I interferon signature had a lower likelihood of response to therapy, while a third group appeared immunologically inactive by immunophenotyping at enrollment but with chronic renal injuries. Main immune profiles could be distilled down to 5 simple cytometric parameters that recapitulate several of the associations, highlighting the potential for blood immune profiling to translate to clinically useful non-invasive metrics to assess immune-mediated disease in LN.

Alternative lengthening of telomeres: mechanism and the pathogenesis of cancer

Telomere maintenance and elongation allows cells to gain replicative immortality and evade cellular senescence during cancer development. While most cancers use telomerase to maintain telomere lengths, a subset of cancers engage the alternative lengthening of telomeres (ALT) pathway for telomere maintenance. ALT is present in 5%-10% of all cancers, although the prevalence is dramatically higher in certain cancer types, including complex karyotype sarcomas, isocitrate dehydrogenase-mutant astrocytoma (WHO grade II-IV), pancreatic neuroendocrine tumours, neuroblastoma and chromophobe hepatocellular carcinomas. ALT is maintained through a homology-directed DNA repair mechanism. Resembling break-induced replication, this aberrant process results in dramatic cell-to-cell telomere length heterogeneity, widespread chromosomal instability and chronic replication stress. Additionally, ALT-positive cancers frequently harbour inactivating mutations in either chromatin remodelling proteins (ATRX, DAXX and H3F3A) or DNA damage repair factors (SMARCAL1 and SLX4IP). ALT can readily be detected in tissue by assessing the presence of unique molecular characteristics, such as large ultrabright nuclear telomeric foci or partially single-stranded telomeric DNA circles (C-circles). Importantly, ALT has been validated as a robust diagnostic and prognostic biomarker for certain cancer types and may even be exploited as a therapeutic target via small molecular inhibitors and/or synthetic lethality approaches.

Deep immunophenotyping reveals circulating activated lymphocytes in individuals at risk for rheumatoid arthritis

Rheumatoid arthritis (RA) is a systemic autoimmune disease with currently no universally highly effective prevention strategies. Identifying pathogenic immune phenotypes in 'At-Risk' populations prior to clinical disease onset is crucial to establishing effective prevention strategies. Here, we applied mass cytometry to deeply characterize the immunophenotypes in blood from At-Risk individuals identified through the presence of serum antibodies to citrullinated protein antigens (ACPA) and/or first-degree relative (FDR) status (n=52), as compared to established RA (n=67), and healthy controls (n=48). We identified significant cell expansions in At-Risk individuals compared with controls, including CCR2+CD4+ T cells, T peripheral helper (Tph) cells, type 1 T helper cells, and CXCR5+CD8+ T cells. We also found that CD15+ classical monocytes were specifically expanded in ACPA-negative FDRs, and an activated PAX5 low naïve B cell population was expanded in ACPA-positive FDRs. Further, we developed an "RA immunophenotype score" classification method based on the degree of enrichment of cell states relevant to established RA patients. This score significantly distinguished At-Risk individuals from controls. In all, we systematically identified activated lymphocyte phenotypes in At-Risk individuals, along with immunophenotypic differences among both ACPA+ and ACPA-FDR At-Risk subpopulations. Our classification model provides a promising approach for understanding RA pathogenesis with the goal to further improve prevention strategies and identify novel therapeutic targets.

The exoribonuclease XRN2 mediates degradation of the long non-coding telomeric RNA TERRA

The telomeric repeat-containing RNA, TERRA, associates with both telomeric DNA and telomeric proteins, often forming RNA:DNA hybrids (R-loops). TERRA is most abundant in cancer cells utilizing the alternative lengthening of telomeres (ALT) pathway for telomere maintenance, suggesting that persistent TERRA R-loops may contribute to activation of the ALT mechanism. Therefore, we sought to identify the enzyme(s) that regulate TERRA metabolism in mammalian cells. Here, we identify that the 5'-3' exoribonuclease XRN2 regulates the stability of TERRA RNA. Moreover, while stabilization of TERRA alone was insufficient to drive ALT, depletion of XRN2 in ALT-positive cells led to a significant increase in TERRA R-loops and exacerbated ALT activity. Together, our findings highlight XRN2 as a key determinant of TERRA metabolism and telomere stability in cancer cells that rely on the ALT pathway.

Implementation of a Standardized Shared Decision-making Bundle to Improve Communication Practices in the Neurocritical Care Unit

Background and Objective

Shared decision-making (SDM) aligns patient preferences with health care team treatment goals. This quality improvement initiative implemented a standardized SDM bundle within a neurocritical care unit (NCCU), where unique demands make existing, provider-driven SDM practices challenging.

Methods

An interprofessional team defined key issues, identified barriers, and created change ideas to drive implementation of an SDM bundle using the Institute for Healthcare Improvement Model for Improvement framework incorporating Plan-Do-Study-Act cycles. The SDM bundle included (1) a health care team huddle pre-SDM and post-SDM conversation; (2) a social worker-driven SDM conversation with the patient family, including core standardized communication elements to ensure consistency and quality; and (3) an SDM documentation tool within the electronic medical record to ensure the SDM conversation was accessible to all health care team members. The primary outcome measure was percentage of SDM conversations documented.

Results

Documentation of SDM conversations improved by 56%, from 27% to 83% pre/postintervention. Average time to documentation decreased by 4 days, from day 9 preintervention to day 5 postintervention. There was no significant change in NCCU length of stay, nor did palliative care consultation rates increase. Postintervention, SDM team huddle compliance was 94.3%.

Discussion

A team-driven, standardized SDM bundle that integrates with health care team workflows enabled SDM conversations to occur earlier and resulted in improved documentation of SDM conversations. Team-driven SDM bundles have the potential to improve communication and promote early alignment with patient family goals, preferences, and values.

MACROPHAGE SWITCHING: POLARIZATION AND MOBILIZATION AFTER TRAUMA

ABSTRACT

Introduction: Trauma alters the immune response in numerous ways, affecting both the innate and adaptive responses. Macrophages play an important role in inflammation and wound healing following injury. We hypothesize that macrophages mobilize from the circulation to the site of injury and secondary sites after trauma, with a transition from proinflammatory (M1) shortly after trauma to anti-inflammatory (M2) at later time points. Methods: C57Bl6 mice (n = 6/group) underwent a polytrauma model using cardiac puncture/hemorrhage, pseudofemoral fracture, and liver crush injury. The animals were killed at several time points: uninjured, 24 h, and 7 days. Peripheral blood mononuclear cells, spleen, liver nonparenchymal cells, and lung were harvested, processed, and stained for flow cytometry. Macrophages were identified as CD68 + ; M1 macrophages were identified as iNOS + ; M2 macrophages as arginase 1 + . Results: We saw a slight presence of M1 macrophages at baseline in peripheral blood mononuclear cells (6.6%), with no significant change at 24 h and 7 days after polytrauma. In contrast, the spleen has a larger population of M1 macrophages at baseline (27.7%), with levels decreasing at 24 h and 7 days after trauma (20.6% and 12.6%, respectively). A similar trend is seen in the lung where at baseline 14.9% of CD68 + macrophages are M1, with subsequent continual decrease reaching 8.7% at 24 h and 4.4% at 7 days after polytrauma. M1 macrophages in the liver represent 14.3% of CD68 + population in the liver nonparenchymal cells at baseline. This percentage increases to 20.8% after trauma and decreases at 7 days after polytrauma (13.4%). There are few M2 macrophages in circulating peripheral blood mononuclear cells and in spleen at baseline and after trauma. The percentage of M2 macrophages in the lungs remains constant after trauma (7.2% at 24 h and 9.2% at 7 days). In contrast, a large proportion of M2 macrophages are seen in the liver at baseline (36.0%). This percentage trends upward and reaches 45.6% acutely after trauma and drops to 21.4% at 7 days. The phenotypic changes in macrophages seen in the lungs did not correlate with a functional change in the ability of the macrophages to perform oxidative burst, with an increase from 2.0% at baseline to 22.1% at 7 days after polytrauma ( P = 0.0258). Conclusion: Macrophage phenotypic changes after polytrauma are noted, especially with a decrease in the lung M1 phenotype and a short-term increase in the M2 phenotype in the liver. However, macrophage function as measured by oxidative burst increased over the time course of trauma, which may signify a change in subset polarization after injury not captured by the typical macrophage phenotypes.

Longitudinal Immune Cell Profiling in Patients With Early Systemic Lupus Erythematosus

OBJECTIVES

To investigate the immune cell profiles of patients with systemic lupus erythematosus (SLE), and to identify longitudinal changes in those profiles over time.

METHODS

We employed mass cytometry with 3 different panels of 38-39 markers (an immunophenotyping panel, a T cell/monocyte panel, and a B cell panel) in cryopreserved peripheral blood mononuclear cells (PBMCs) from 9 patients with early SLE, 15 patients with established SLE, and 14 controls without autoimmune disease. We used machine learning-driven clustering, flow self-organizing maps, and dimensional reduction with t-distributed stochastic neighbor embedding to identify unique cell populations in early SLE and established SLE. We used mass cytometry data of PBMCs from 19 patients with early rheumatoid arthritis (RA) and 23 controls to compare levels of specific cell populations in early RA and SLE. For the 9 patients with early SLE, longitudinal mass cytometry analysis was applied to PBMCs at enrollment, 6 months after enrollment, and 1 year after enrollment. Serum samples were also assayed for 65 cytokines using Luminex multiplex assay, and associations between cell types and cytokines/chemokines were assessed.

RESULTS

Levels of peripheral helper T cells, follicular helper T (Tfh) cells, and several Ki-67+ proliferating subsets (ICOS+Ki-67+ CD8 T cells, Ki-67+ regulatory T cells, CD19intermediate Ki-67high plasmablasts, and PU.1high Ki-67high monocytes) were increased in patients with early SLE, with more prominent alterations than were seen in patients with early RA. Longitudinal mass cytometry and multiplex serum cytokine assays of samples from patients with early SLE revealed that levels of Tfh cells and CXCL10 had decreased 1 year after enrollment. Levels of CXCL13 were positively correlated with levels of several of the expanded cell populations in early SLE.

CONCLUSION

Two major helper T cell subsets and unique Ki-67+ proliferating immune cell subsets were expanded in patients in the early phase of SLE, and the immunologic features characteristic of early SLE evolved over time.

Distinct Injury Responsive Regulatory T Cells Identified by Multi-Dimensional Phenotyping

CD4⁺ regulatory T cells (Tregs) activate and expand in response to different types of injuries, suggesting that they play a critical role in controlling the immune response to tissue and cell damage. This project used multi-dimensional profiling techniques to comprehensively characterize injury responsive Tregs in mice. We show that CD44^high Tregs expand in response to injury and were highly suppressive when compared to CD44^low Tregs. T cell receptor (TCR) repertoire analysis revealed that the CD44^high Treg population undergo TCRαβ clonal expansion as well as increased TCR CDR3 diversity. Bulk RNA sequencing and single-cell RNA sequencing with paired TCR clonotype analysis identified unique differences between CD44^high and CD44^low Tregs and specific upregulation of genes in Tregs with expanded TCR clonotypes. Gene ontology analysis for molecular function of RNA sequencing data identified chemokine receptors and cell division as the most enriched functional terms in CD44^high Tregs versus CD44^low Tregs. Mass cytometry (CyTOF) analysis of Tregs from injured and uninjured mice verified protein expression of these genes on CD44^high Tregs, with injury-induced increases in Helios, Galectin-3 and PYCARD expression. Taken together, these data indicate that injury triggers the expansion of a highly suppressive CD44^high Treg population that is transcriptionally and phenotypically distinct from CD44^low Tregs suggesting that they actively participate in controlling immune responses to injury and tissue damage.

Checkpoint blockade-induced CD8+ T cell differentiation in head and neck cancer responders

Background

Immune checkpoint blockade (ICB) response in recurrent/metastatic head and neck squamous cell carcinoma (HNSCC) is limited to 15%–20% of patients and underpinnings of resistance remain undefined.

Methods

Starting with an anti-PD1 sensitive murine HNSCC cell line, we generated an isogenic anti-PD1 resistant model. Mass cytometry was used to delineate tumor microenvironments of both sensitive parental murine oral carcinoma (MOC1) and resistant MOC1esc1 tumors. To examine heterogeneity and clonal dynamics of tumor infiltrating lymphocytes (TILs), we applied paired single-cell RNA and TCR sequencing in three HNSCC models.

Results

Anti-PD1 resistant MOC1esc1 line displayed a conserved cell intrinsic immune evasion signature. Immunoprofiling showed distinct baseline tumor microenvironments of MOC1 and MOC1esc1, as well as the remodeling of immune compartments on ICB in MOC1esc1 tumors. Single cell sequencing analysis identified several CD8 +TIL subsets including Tcf7 +Pd1− (naïve/memory-like), Tcf7 +Pd1+ (progenitor), and Tcf7-Pd1+ (differentiated effector). Mapping TCR shared fractions identified that successful anti-PD1 or anti-CTLA4 therapy-induced higher post-treatment T cell lineage transitions.

Conclusions

These data highlight critical aspects of CD8 +TIL heterogeneity and differentiation and suggest facilitation of CD8 +TIL differentiation as a strategy to improve HNSCC ICB response.

164 Potent tumor organoid infiltration and killing by PBMC-derived effector cells

Background

Alloplex Biotherapeutics has developed a novel autologous cellular therapy for cancer that uses ENgineered Leukocyte ImmunoSTimulatory cell lines called ENLIST cells to activate and expand a heterogeneous population of tumor killing effector cells from human peripheral blood mononuclear cells (PBMCs). The 2-week manufacturing process from PBMCs consistently results 300-fold expansion of NK cells, CD8+ T cells, gamma/delta T cells, NKT cells and some CD4+ T cells, collectively called SUPLEXA therapeutic cells. SUPLEXA cells will be delivered back to cancer patients via intravenous administrations on a weekly schedule as an autologous adoptive cellular immunotherapy for cancer. In this study, we tested SUPLEXA cells developed from normal healthy volunteer PBMCs for their ability to infiltrate and kill patient-derived tumor organoids (PDO) as a pre-clinical assessment for potency against 2 different types of tumor organoids.

Methods

Tumor organoids derived from colorectal cancer (CRC) or non-small cell lung carcinoma (NSCLC) patients were labeled with cell-trace red dye and plated at equal density in a 96-well plate. After 3 days culture, SUPLEXA cells were thawed (82.8% viable), labeled with cell-trace violet dye, and added to PDO at 1:2 serial diluted numbers ranging from 2 million to 7,800 cells per well. Fluorescent images were captured at 24 hours after adding SUPLEXA cells to PDO models to measure PDO size, tumor infiltration, and PDO killing.

Results

Adding SUPLEXA cells to PDO from CRC and NSCLC resulted in significant infiltration and killing of organoids by 24 hours as shown by the fluorescent images and the organoid size plot for the CRC PDO model (figure 1). Significant reduction in PDO size was observed by adding 31,240 SUPLEXA cells. Similar results were observed with the NSCLC PDO model with significant reduction in PDO size by adding 15,600 SUPLEXA cells. Obvious organoid infiltration was observed in both PDO models and organoid fluorescence was significantly reduced by addition of SUPLEXA cells in both PDO models to suggest that SUPLEXA cells were able to reduce tumor burden (figure 2).

Abstract 164 Figure 1

CRC organoid infiltration and killing by SUPLEXA. A representative fluorescent image of CRC organoid killing with addition of increasing SUPLEXA cell numbers and a plot showing statistical analysis of 6 replicate wells for changes in CRC organoid size in relation to SUPLEXA cell number additions

Abstract 164 Figure 2

Dose-dependent killing in CRC and NSCLC PDO models. CRC and NSCLC organoids were detected by total red fluorescence at 24 hours after adding the indicated numbers of SUPLEXA cells. Loss of red fluorescence after adding SUPLEXA is a measure of overall tumor cell killing/burden in organoids. Data is plotted as mean ± SEM for n=6 replicates per group.

Conclusions

SUPLEXA cells infiltrated and killed tumor cells in patient-derived organoids within 24 hours of culture at low cell concentrations indicating potent tumor killing activity. The observed activity in both colorectal and lung cancer organoid models support broad anti-tumor killing activity by SUPLEXA. These results provide further evidence that PBMCs from cancer patients can be activated and expanded by our approach as a novel autologous cellular immunotherapy for cancer.

miR-378-3p Knockdown Recapitulates Many of the Features of Myelodysplastic Syndromes

Myelodysplastic syndromes (MDS) are clonal neoplasms of the hematopoietic stem cell that result in aberrant differentiation of hematopoietic lineages due to a wide range of underlying genetic, epigenetic, and other causes. Despite the myriad etiologies, there is a recognizable MDS phenotype that has been associated with microRNA (miRNA) aberrant expression. A model of aberrant myeloid maturation mimicking MDS that is seen in MDS has been created using a stable knockdown of miR-378-3p. This model exhibited a transcriptional profile that indicates aberrant maturation and function, showed immunophenotypic and morphologic dysplasia, and displays the aberrant growth and function that characterizes MDS. Moreover, aberrant signal transduction in response to stimulation was demonstrated that is specific to the stage of myeloid maturation and mimics that seen in MDS patient samples using mass cytometry (CyTOF). The aberrant signaling, immunophenotypic changes, cellular growth, and colony formation ability seen in this myeloid model could be reversed with azacytidine (AZA) albeit without significant improvement of neutrophil function.

Diagnosis of Coma

The differential diagnosis for the comatose patient is includes structural abnormality, seizure, encephalitis, metabolic derangements, and toxicologic etiologies. Identifying and treating the underlying pathology in a timely manner is critical for the patient's outcome. We provide a structured approach to taking a history and performing a physical examination for this patient population. We discuss diagnostic testing and treatment methodologies for each of the common causes of coma. Our current understanding of the mechanisms of coma is insufficient to accurately predict the patient's clinical trajectory and more work needs to be done to investigate potential treatments for this often fatal disorder.

Augmenting emergency granulopoiesis with CpG conditioned mesenchymal stromal cells in murine neutropenic sepsis

Patients with immune deficiencies from cancers and associated treatments represent a growing population within the intensive care unit with increased risk of morbidity and mortality from sepsis. Mesenchymal stromal cells (MSCs) are an integral part of the hematopoietic niche and express toll-like receptors, making them candidate cells to sense and translate pathogenic signals into an innate immune response. In this study, we demonstrate that MSCs administered therapeutically in a murine model of radiation-associated neutropenia have dual actions to confer a survival benefit in Pseudomonas aeruginosa pneumo-sepsis that is not from improved bacterial clearance. First, MSCs augment the neutrophil response to infection, an effect that is enhanced when MSCs are preconditioned with CpG oligodeoxynucleotide, a toll-like receptor 9 agonist. Using cytometry by time of flight, we identified proliferating neutrophils (Ly6GlowKi-67+) as the main expanded cell population within the bone marrow. Further analysis revealed that CpG-MSCs expand a lineage restricted progenitor population (Lin-Sca1+C-kit+CD150-CD48+) in the bone marrow, which corresponded to a doubling in the myeloid proliferation and differentiation potential in response to infection compared with control. Despite increased neutrophils, no reduction in organ bacterial count was observed between experimental groups. However, the second effect exerted by CpG-MSCs is to attenuate organ damage, particularly in the lungs. Neutrophils obtained from irradiated mice and cocultured with CpG-MSCs had decreased neutrophil extracellular trap formation, which was associated with decreased citrullinated H3 staining in the lungs of mice given CpG-MSCs in vivo. Thus, this preclinical study provides evidence for the therapeutic potential of MSCs in neutropenic sepsis.

Immune phenotyping of diverse syngeneic murine brain tumors identifies immunologically distinct types

Immunotherapy has emerged as a promising approach to treat cancer, however, its efficacy in highly malignant brain-tumors, glioblastomas (GBM), is limited. Here, we generate distinct imageable syngeneic mouse GBM-tumor models and utilize RNA-sequencing, CyTOF and correlative immunohistochemistry to assess immune-profiles in these models. We identify immunologically-inert and -active syngeneic-tumor types and show that inert tumors have an immune-suppressive phenotype with numerous exhausted CD8 T cells and resident macrophages; fewer eosinophils and SiglecF+ macrophages. To mimic the clinical-settings of first line of GBM-treatment, we show that tumor-resection invigorates an anti-tumor response via increasing T cells, activated microglia and SiglecF+ macrophages and decreasing resident macrophages. A comparative CyTOF analysis of resected-tumor samples from GBM-patients and mouse GBM-tumors show stark similarities in one of the mouse GBM-tumors tested. These findings guide informed choices for use of GBM models for immunotherapeutic interventions and offer a potential to facilitate immune-therapies in GBM patients.

Syngeneic mouse models for glioblastoma (GBM) cannot fully recapitulate clinical findings and response to therapy in patients. Here the authors perform a comprehensive immune profiling of different syngeneic GBM tumour models and compare it with the immune landscape of GBM patients to identify similarities and potential confounding differences.

Increased regulatory T cells suppress traumatic injury induced inflammation and control adaptive immune cell expansion in an experimental model of burn trauma

Trauma-induced inflammatory dysfunction is a lesser appreciated field of conventional immunology. In fact, traumatic injury is the leading cause of death in the US for people under 44 years old and resultantly disrupts immune homeostasis that puts injured patients at risk for developing opportunistic infections and succumbing to post-injury sepsis. Regulatory T cells (Tregs) are unique cells that contribute to immune balance but play a key role in the undesirable post-trauma immune suppression by repressing important Th-1 type immunity. Interestingly however, several reports demonstrate that Tregs confer a survival advantage in trauma. Therefore, it raises the question, do injured patients with quantitively enhanced Tregs fare better than those with less Tregs? Accordingly, we examined the role of increased Tregs on immune cell subsets in a murine burn-trauma model.

C57BL/6 mice were treated with anti-DR3 to increase Tregs before burn trauma. Mice treated with anti-DR3 prior to burn and secondary pseudomonas aeruginosa infection showed improved survival compared with untreated mice. CyTOF analysis revealed burn-injured mice given anti-DR3 showed increased counts of Ki-67+ splenic PMN-MDSCs compared to sham and burn-injured control mice. This corresponded with higher levels of PMN chemoattractants by stimulated splenocytes from burn-injured mice given DR3. Sham and burn-injured mice with higher Tregs also had increased numbers of activated γδ T cells compared to untreated mice, suggesting that these cells are regulated by an increase in Tregs. This study indicates that in trauma, it may be necessary to maintain high Treg levels to alleviate trauma-induced immune dysregulation and restore immune homeostasis.

Circulating Factors in Trauma Plasma Activate Specific Human Immune Cell Subsets

BACKGROUND

Trauma causes tissue injury that results in the release of damage associated molecular patterns (DAMPs) and other mediators at the site of injury and systemically. Such mediators disrupt immune system homeostasis and may activate multicellular immune responses with downstream complications such as the development of infections and sepsis. To characterize these alterations, we used time-of-flight mass cytometry to determine how trauma plasma affects normal peripheral blood mononuclear cell (PBMC) activation to gain insights into the kinetics and nature of trauma-induced circulating factors on human immune cell populations. A better understanding of the components that activate cells in trauma may aid in the discovery of therapeutic targets.

METHODS

PBMCs from healthy volunteers were cultured with 5% plasma (healthy, trauma-1day, or trauma-3day) or known DAMPs for 24 h. Samples were stained with a broad immunophenotyping CyTOF antibody panel. Multiplex (Luminex) cytokine assays were used to measure differences in multiple cytokine levels in healthy and trauma plasma samples.

RESULTS

Plasma from day 1, but not day 3 trauma patients induced the acute expansion of CD11c+ NK cells and CD73+/CCR7+ CD8 T cell subpopulations. Additionally, trauma plasma did not induce CD4+ T cell expansion but did cause a phenotypic shift towards CD38+/CCR7+ expressing CD4+ T cells. Multiplex analysis of cytokines by Luminex showed increased levels of IL-1RA, IL-6 and IL-15 in trauma-1day plasma. Similar to trauma day 1 plasma, PBMC stimulation with known DAMPs showed activation and expansion of CD11c+ NK cells.

CONCLUSIONS

We hypothesized that circulating factors in trauma plasma would induce phenotypic activation of normal human immune cell subsets. Using an unbiased approach, we identified specific changes in immune cell subsets that respond to trauma plasma. Additionally, CD11c+ NK cells expanded in response to DAMPs and LPS, suggesting they may also be responding to similar components in trauma plasma. Collectively, our data demonstrate that the normal PBMC response to trauma plasma involves marked changes in specific subsets of NK and CD8+ T cell populations. Future studies will target the function of these trauma plasma reactive immune cell subsets. These findings have important implications for the field of acute traumatic injuries.

PD-1hiCXCR5- T peripheral helper cells promote B cell responses in lupus via MAF and IL-21

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by pathologic T cell-B cell interactions and autoantibody production. Defining the T cell populations that drive B cell responses in SLE may enable design of therapies that specifically target pathologic cell subsets. Here, we evaluated the phenotypes of CD4+ T cells in the circulation of 52 SLE patients drawn from multiple cohorts and identified a highly expanded PD-1hiCXCR5-CD4+ T cell population. Cytometric, transcriptomic, and functional assays demonstrated that PD-1hiCXCR5-CD4+ T cells from SLE patients are T peripheral helper (Tph) cells, a CXCR5- T cell population that stimulates B cell responses via IL-21. The frequency of Tph cells, but not T follicular helper (Tfh) cells, correlated with both clinical disease activity and the frequency of CD11c+ B cells in SLE patients. PD-1hiCD4+ T cells were found within lupus nephritis kidneys and correlated with B cell numbers in the kidney. Both IL-21 neutralization and CRISPR-mediated deletion of MAF abrogated the ability of Tph cells to induce memory B cell differentiation into plasmablasts in vitro. These findings identify Tph cells as a highly expanded T cell population in SLE and suggest a key role for Tph cells in stimulating pathologic B cell responses.

2395LGE CMR predicts sudden death and VT in adults with repaired tetralogy of Fallot - a prospective study with 3500 patient follow up years

Background

Adults with repaired tetralogy of Fallot (rtoF) are at risk of ventricular arrhythmia and sudden cardiac death (SCD). Cross-sectional data suggest association of late gadolinium enhancement (LGE) cardiovascular magnetic resonance imaging (CMR) with adverse clinical risk factors

Purpose

We sought to determine prognosis related to LGE CMR.

Methods

In this prospective cohort study the primary composite outcome comprised the first of cardiovascular death (SCD or heart failure-related), aborted SCD (successfully resuscitated cardiac arrest or appropriate AICD shock for ventricular fibrillation), and clinical sustained ventricular tachycardia (VT>30 seconds duration).

Results

In 531 rtoF patients (median age 32; 23–42, 296 (56%) male, NYHA≥II 17%) followed up after LGE CMR for median 5 (1.7–8.9) years, there were 39 primary composite outcomes: 10 SCD, 11 heart failure related deaths (2 perioperative RV failure), 2 aborted SCD and 16 clinical sustained VT events. At study end, there were 28 ventricular arrhythmic events in 28 rtoF patients (10 SCD, 16 clinical sustained VT, 2 aborted VF) that were significantly predicted by RV LGE extent (HR 1.45 CI: 1.3–1.6; P<0.001).

Univariable predictors of the primary outcome were RV LGE score; HR: 1.44 (1.31–1.57; p<0.001), (Figure) together with older age; HR: 1.05 (1.02–1.07; P<0.001), late repair; HR: 1.04 (1.02–1.07; p<0.001), lower RV ejection fraction; HR: 0.92 (0.89–0.95; p<0.001), larger RVOT akinetic length; HR: 1.04 (1.02–1.06; p<0.001) larger right atrial area; HR: 1.2 (1.12–1.29; p<0.001); higher BNP levels; HR: 1.01 (1–1.02; p<0.001), lower peak VO2; HR: 0.89 (0.83–0.96; p=0.001), prior atrial arrhythmia; HR: 5.3 (2.8–10.07; p<0.001), and non-sustained VT; HR: 4.1 (2.1–7.7; p<0.001). Inducible VT did not predict the primary outcome; HR: 2.1 (0.57–8; p=0.25)

In multivariable analysis both RV LGE score and indexed right atrial area (RAAi) only, remained predictive of the primary outcome (HR 1.29 CI: 1.12–1.49; p<0.001 and HR 1.1 CI: 1.02–1.12; p=0.01, respectively). Patients could accordingly be stratified such that supramedian RV LGE score (≥5) and RAAi ≥16cm2/m2 had 5-year event free survival 84% vs 94% for supramedian RV LGE score (≥5) and RAAi <16cm2/m2 or 98% for inframedian RV LGE score with RAAI<16cm2/m2. Figure.

Conclusions

For every unit increase in CMR defined RV fibrosis score there is a 44% increased risk of sudden cardiac death and VT. LGE CMR and maximal right atrial area should therefore be incorporated into risk stratification for sudden death in adults with rTOF.

Acknowledgement/Funding

British heart foundation

Abstract 1509: Identification of immunotherapy resistance mechanisms within tumor microenvironment in a mouse model of oral squamous cell carcinoma

The response rate of 15-20% with anti-PD1 in head and neck squamous cell carcinoma (HNSCC) highlights the urgent need for strategies to overcome resistance. Our lab has previously developed a carcinogen-induced immunocompetent murine oral carcinoma (MOC) model to study HNSCC immunobiology. Specifically, MOC1 is an immunogenic cell line that, despite sensitivity to anti-PD-1, exhibits occasional development of escape tumors (MOC1esc). MOC1esc escape tumors display a resistance phenotype similar to those observed in HNSCC patients undergoing anti-PD1 therapy. When independent escape tumors are harvested and re-transplanted into naïve mice, they grow progressively and are resistant to anti-PD1 therapy. Intriguingly, whileMOC1esc is resistant to anti-PD1, it is completely rejected in tumor bearing mice treated with anti-CTLA4. Therefore, the anti-PD1 responsive MOC1 and resistant MOC1esc mouse model is an isogenic system that provides an excellent opportunity to study mechanism(s) in adaptive resistance to anti-PD1 therapy of HNSCC. To gain a comprehensive insight into the tumor microenvironment (TME) as a contributor to adaptive resistance, we analyzed tumor infiltrating lymphocytes (TIL) in naïve MOC1 and MOC1esc tumors using mass cytometry time-of-flight (CyTOF) with a 38-cell marker panel.MOC1esc tumors were highly infiltrated by CD103+ effector/memory regulatory T cells (Tregs) and M2-like tumor associated macrophages (TAMs), while MOC1 tumors have more M1-like TAMs and neutrophils. Furthermore, we observed that both anti-PD1 and anti-CTLA4 treatment dramatically expanded CD8+ T cells and decreased neutrophils in MOC1esc tumors. In responding MOC1esc tumors, anti-CTLA4 treatment resulted in depleted Tregs, decreased M2-like TAMs and neutrophils, as well as a striking increase in M1-like TAMs compared with isotype control treated tumors. In contrast, anti-PD1 treated resistant MOC1esc tumors showed decreased M1-like TAMs, while M2-like TAMs were increased compared with controls. Tregs were not affected by anti-PD1 treatment. Therefore, the comparison between the TME of anti-PD1 treated resistant tumors and anti-CTLA4 treated responding tumors suggeststhat Tregs, neutrophils, and TAMs may contribute to the sensitivity (or resistance) to checkpoint blockade therapy. Ongoing studies will test the functional contribution of these distinct TME components in antitumor immunity including cytokine production, proliferative capacity, and their roles in immunotherapy resistance. In summary, this study identified immune modulators within TME involved in adaptive immunotherapy resistance of HNSCC. Findings from this study have advanced our understanding of HNSCC immunotherapy resistance and will accelerate the discovery of new therapeutic targets and biomarkers for adaptive resistance.

Citation Format: Liye Zhou, Yasutaka Nakahori, Fei Guo, Joshua Keegan, Rachel Riley, James A. Lederer, Ravindra Uppaluri. Identification of immunotherapy resistance mechanisms within tumor microenvironment in a mouse model of oral squamous cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1509.

Encephalopathy and Delirium

Delirium has high prevalence in the intensive care unit (ICU) and carries high morbidity. Delirium is often underrecognized, and implementation of validated screening strategies increases detection rates. Strategies to minimize delirium include limitation or avoidance of certain medications (especially benzodiazepines), frequent reorientation, maintenance of normal sleep/wake cycles, and provision of hearing and vision aids. Optimal treatment of delirium once it occurs is unclear, but antipsychotics may have beneficial effects. Sedative medications to manage pain and agitation are often necessary in the ICU; however, they may contribute to delirium. The agent used should be targeted to the patient’s specific situation. Daily sedation interruptions and targeting light rather than deep sedation help to minimize the doses used. In a subset of patients specific to the neurologic ICU, deeper sedation may be required to avoid intracranial pressure crises.

Methods for high-dimensional analysis of cells dissociated from cryopreserved synovial tissue

Background

Detailed molecular analyses of cells from rheumatoid arthritis (RA) synovium hold promise in identifying cellular phenotypes that drive tissue pathology and joint damage. The Accelerating Medicines Partnership RA/SLE Network aims to deconstruct autoimmune pathology by examining cells within target tissues through multiple high-dimensional assays. Robust standardized protocols need to be developed before cellular phenotypes at a single cell level can be effectively compared across patient samples.

Methods

Multiple clinical sites collected cryopreserved synovial tissue fragments from arthroplasty and synovial biopsy in a 10% DMSO solution. Mechanical and enzymatic dissociation parameters were optimized for viable cell extraction and surface protein preservation for cell sorting and mass cytometry, as well as for reproducibility in RNA sequencing (RNA-seq). Cryopreserved synovial samples were collectively analyzed at a central processing site by a custom-designed and validated 35-marker mass cytometry panel. In parallel, each sample was flow sorted into fibroblast, T-cell, B-cell, and macrophage suspensions for bulk population RNA-seq and plate-based single-cell CEL-Seq2 RNA-seq.

Results

Upon dissociation, cryopreserved synovial tissue fragments yielded a high frequency of viable cells, comparable to samples undergoing immediate processing. Optimization of synovial tissue dissociation across six clinical collection sites with ~ 30 arthroplasty and ~ 20 biopsy samples yielded a consensus digestion protocol using 100 μg/ml of Liberase™ TL enzyme preparation. This protocol yielded immune and stromal cell lineages with preserved surface markers and minimized variability across replicate RNA-seq transcriptomes. Mass cytometry analysis of cells from cryopreserved synovium distinguished diverse fibroblast phenotypes, distinct populations of memory B cells and antibody-secreting cells, and multiple CD4⁺ and CD8⁺ T-cell activation states. Bulk RNA-seq of sorted cell populations demonstrated robust separation of synovial lymphocytes, fibroblasts, and macrophages. Single-cell RNA-seq produced transcriptomes of over 1000 genes/cell, including transcripts encoding characteristic lineage markers identified.

Conclusions

We have established a robust protocol to acquire viable cells from cryopreserved synovial tissue with intact transcriptomes and cell surface phenotypes. A centralized pipeline to generate multiple high-dimensional analyses of synovial tissue samples collected across a collaborative network was developed. Integrated analysis of such datasets from large patient cohorts may help define molecular heterogeneity within RA pathology and identify new therapeutic targets and biomarkers.

Electronic supplementary material

The online version of this article (10.1186/s13075-018-1631-y) contains supplementary material, which is available to authorized users.

Phenotyping the Immune Response to Trauma: A Multiparametric Systems Immunology Approach

OBJECTIVE

Trauma induces a complex immune response that requires a systems biology research approach. Here, we used a novel technology, mass cytometry by time-of-flight, to comprehensively characterize the multicellular response to trauma.

DESIGN

Peripheral blood mononuclear cells samples were stained with a 38-marker immunophenotyping cytometry by time-of-flight panel. Separately, matched peripheral blood mononuclear cells were stimulated in vitro with heat-killed Streptococcus pneumoniae or CD3/CD28 antibodies and stained with a 38-marker cytokine panel. Monocytes were studied for phagocytosis and oxidative burst.

SETTING

Single-institution level 1 trauma center.

PATIENTS OR SUBJECTS

Trauma patients with injury severity scores greater than 20 (n = 10) at days 1, 3, and 5 after injury, and age- and gender-matched controls.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Trauma-induced expansion of Th17-type CD4 T cells was seen with increased expression of interleukin-17 and interleukin-22 by day 5 after injury. Natural killer cells showed reduced T-bet expression at day 1 with an associated decrease in tumor necrosis factor-β, interferon-γ, and monocyte chemoattractant protein-1. Monocytes showed robust expansion following trauma but displayed decreased stimulated proinflammatory cytokine production and significantly reduced human leukocyte antigen - antigen D related expression. Further analysis of trauma-induced monocytes indicated that phagocytosis was no different from controls. However, monocyte oxidative burst after stimulation increased significantly after injury.

CONCLUSIONS

Using cytometry by time-of-flight, we were able to identify several major time-dependent phenotypic changes in blood immune cell subsets that occur following trauma, including induction of Th17-type CD4 T cells, reduced T-bet expression by natural killer cells, and expansion of blood monocytes with less proinflammatory cytokine response to bacterial stimulation and less human leukocyte antigen - antigen D related. We hypothesized that monocyte function might be suppressed after injury. However, monocyte phagocytosis was normal and oxidative burst was augmented, suggesting that their innate antimicrobial functions were preserved. Future studies will better characterize the cell subsets identified as being significantly altered by trauma using cytometry by time-of-flight, RNAseq technology, and functional studies.

CD45 Expression in Mitral Valve Endothelial Cells After Myocardial Infarction

RATIONALE

Ischemic mitral regurgitation, a complication after myocardial infarction (MI), induces adaptive mitral valve (MV) responses that may be initially beneficial but eventually lead to leaflet fibrosis and MV dysfunction. We sought to examine the MV endothelial response and its potential contribution to ischemic mitral regurgitation.

OBJECTIVE

Endothelial, interstitial, and hematopoietic cells in MVs from post-MI sheep were quantified. MV endothelial CD45, found post MI, was analyzed in vitro.

METHODS AND RESULTS

Ovine MVs, harvested 6 months after inferior MI, showed CD45, a protein tyrosine phosphatase, colocalized with von Willebrand factor, an endothelial marker. Flow cytometry of MV cells revealed significant increases in CD45⁺ endothelial cells (VE-cadherin⁺/CD45⁺/α-smooth muscle actin [SMA]⁺ and VE-cadherin⁺/CD45⁺/αSMA- cells) and possible fibrocytes (VE-cadherin^-/CD45⁺/αSMA⁺) in inferior MI compared with sham-operated and normal sheep. CD45⁺ cells correlated with MV fibrosis and mitral regurgitation severity. VE-cadherin⁺/CD45⁺/αSMA⁺ cells suggested that CD45 may be linked to endothelial-to-mesenchymal transition (EndMT). MV endothelial cells treated with transforming growth factor-β1 to induce EndMT expressed CD45 and fibrosis markers collagen 1 and 3 and transforming growth factor-β1 to 3, not observed in transforming growth factor-β1-treated arterial endothelial cells. A CD45 protein tyrosine phosphatase inhibitor blocked induction of EndMT and fibrosis markers and inhibited EndMT-associated migration of MV endothelial cells.

CONCLUSIONS

MV endothelial cells express CD45, both in vivo post MI and in vitro in response to transforming growth factor-β1. A CD45 phosphatase inhibitor blocked hallmarks of EndMT in MV endothelial cells. These results point to a novel, functional requirement for CD45 phosphatase activity in EndMT. The contribution of CD45⁺ endothelial cells to MV adaptation and fibrosis post MI warrants investigation.

Valvular interstitial cells suppress calcification of valvular endothelial cells

BACKGROUND

Calcific aortic valve disease (CAVD) is the most common heart valve disease in the Western world. We previously proposed that valvular endothelial cells (VECs) replenish injured adult valve leaflets via endothelial-to-mesenchymal transformation (EndMT); however, whether EndMT contributes to valvular calcification is unknown. We hypothesized that aortic VECs undergo osteogenic differentiation via an EndMT process that can be inhibited by valvular interstitial cells (VICs).

APPROACH AND RESULTS

VEC clones underwent TGF-β1-mediated EndMT, shown by significantly increased mRNA expression of the EndMT markers α-SMA (5.3 ± 1.2), MMP-2 (13.5 ± 0.6) and Slug (12 ± 2.1) (p < 0.05), (compared to unstimulated controls). To study the effects of VIC on VEC EndMT, clonal populations of VICs were derived from the same valve leaflets, placed in co-culture with VECs, and grown in control/TGF-β1 supplemented media. In the presence of VICs, EndMT was inhibited, shown by decreased mRNA expression of α-SMA (0.1 ± 0.5), MMP-2 (0.1 ± 0.1), and Slug (0.2 ± 0.2) (p < 0.05). When cultured in osteogenic media, VECs demonstrated osteogenic changes confirmed by increase in mRNA expression of osteocalcin (8.6 ± 1.3), osteopontin (3.7 ± 0.3), and Runx2 (5.5 ± 1.5). The VIC presence inhibited VEC osteogenesis, demonstrated by decreased expression of osteocalcin (0.4 ± 0.1) and osteopontin (0.2 ± 0.1) (p < 0.05). Time course analysis suggested that EndMT precedes osteogenesis, shown by an initial increase of α-SMA and MMP-2 (day 7), followed by an increase of osteopontin and osteocalcin (day 14).

CONCLUSIONS

The data indicate that EndMT may precede VEC osteogenesis. This study shows that VICs inhibit VEC EndMT and osteogenesis, indicating the importance of VEC-VIC interactions in valve homeostasis.

Spiral tissue phase velocity mapping in a breath-hold with non-cartesian SENSE

PURPOSE

Tissue phase velocity mapping (TPVM) is capable of reproducibly measuring regional myocardial velocities. However acquisition durations of navigator gated techniques are long and unpredictable while current breath-hold techniques have low temporal resolution. This study presents a spiral TPVM technique which acquires high resolution data within a clinically acceptable breath-hold duration.

METHODS

Ten healthy volunteers are scanned using a spiral sequence with temporal resolution of 24 ms and spatial resolution of 1.7 × 1.7 mm. Retrospective cardiac gating is used to acquire data over the entire cardiac cycle. The acquisition is accelerated by factors of 2 and 3 by use of non-Cartesian SENSE implemented on the Gadgetron GPU system resulting in breath-holds of 17 and 13 heartbeats, respectively. Systolic, early diastolic, and atrial systolic global and regional longitudinal, circumferential, and radial velocities are determined.

RESULTS

Global and regional velocities agree well with those previously reported. The two acceleration factors show no significant differences for any quantitative parameter and the results also closely match previously acquired higher spatial resolution navigator-gated data in the same subjects.

CONCLUSION

By using spiral trajectories and non-Cartesian SENSE high resolution, TPVM data can be acquired within a clinically acceptable breath-hold.

Use of respiratory biofeedback and CLAWS for increased navigator efficiency for imaging the thoracic aorta

A novel technique to guide a subjects' breathing pattern using a respiratory biofeedback (rBF) "game" to improve respiratory efficiency is presented. The continuously adaptive windowing strategy, a fully automatic and highly efficient free-breathing navigator gated technique, is used to acquire the data as it ensures that all potential navigator acceptance windows are possible. This enables the rBF to be fully adaptable to a subject's respiratory pattern. Images of the thoracic aorta acquired using balanced steady-state free precession with continuously adaptive windowing strategy respiratory motion control, with and without rBF, were compared in 10 healthy subjects. Total scan time was reduced by using rBF. The mean scan time was reduced from 7 min 44 s (463 cardiac cycles, ± 127 cc) without rBF to 5 min 43 s (380 cardiac cycles, ± 118 cc) with the use of rBF (P < 0.05). Respiratory efficiency was increased from 45% without rBF to 56% with rBF (P < 0.01). Image quality was the same for both techniques (P = ns). In conclusion, rBF significantly improved respiratory efficiency and reduced acquisition duration without affecting image quality.

The effect of dynamic vessel motion on haemodynamic parameters in the right coronary artery: a combined MR and CFD study

Human right coronary artery (RCA) haemodynamics is investigated using computational fluid dynamics (CFD) based on subject-specific information from magnetic resonance (MR) acquisitions. The dynamically varying vascular geometry is reconstructed from MR images, incorporated in CFD in conjunction with pulsatile flow conditions obtained from MR velocity mapping performed on the same subject. The effects of dynamic vessel motion on instantaneous and cycle-averaged haemodynamic parameters, such as wall shear stress (WSS), time-averaged WSS (TAWSS) and oscillatory shear index (OSI), are examined by comparing an RCA model with a time-varying geometry and those with a static geometry, corresponding to nine different time-points in the cardiac cycle. The results show that the TAWSS is similar for the dynamic and static wall models, both qualitatively and quantitatively (correlation coefficient 0.89-0.95). Conversely, the OSI shows much poorer correlations (correlation coefficient 0.38-0.60), with the best correspondence being observed with the static models constructed from images acquired in late diastole (at t = 0 and 800 ms, the cardiac cycle is 900 ms). These findings suggest that neglecting dynamic motion of the RCA is acceptable if TAWSS is the primary focus but may result in underestimation of haemodynamic parameters related to the oscillatory nature of the blood flow.

Design of a highly stable, high-conversion-efficiency, optical parametric chirped-pulse amplification system with good beam quality

An optical parametric chirped-pulse amplifier (OPCPA) design that provides 40% pump-to-signal conversion efficiency and over-500-mJ signal energy at 1054 nm for front-end injection into a Nd:glass amplifier chain is presented. This OPCPA system is currently being built as the prototype front end for the OMEGA EP (extended performance) laser system at the University of Rochester's Laboratory for Laser Energetics. Using a three-dimensional spatial and temporal numerical model, several design considerations necessary to achieve high conversion efficiency, good output stability, and good beam quality are discussed. The dependence of OPCPA output on the pump beam's spatiotemporal shape and the relative size of seed and pump beams is described. This includes the effects of pump intensity modulation and pump-signal walk-off. The trade-off among efficiency, stability, and low output beam intensity modulation is discussed.

Improved cine cardiovascular magnetic resonance using Clariscan (NC100150 injection)

We evaluated the use of Clariscan 0.75, 2, and 5 mg Fe/kg body weight in six patients to determine optimal dosing for short repetition time cine imaging. Breathhold cine images were acquired in the vertical and horizontal long axes and the short axis. Blood-pool signal-to-noise ratio increased significantly in all planes (p < 0.01) but was least marked in the short axis. Myocardial signal-to-noise ratio increased by a lesser amount (p < 0.05). Myocardial to blood-pool signal-difference-to-noise ratio improved significantly in the long axes (p < 0.05) and was greatest at 2 mg Fe/kg body weight, but changes in the short axis were minor. With the 5-mg Fe/kg body weight dose, the response was reduced or reversed due to T2* effects. Visual assessment improved in all planes (p < 0.05) and was optimal at 2 mg Fe/kg body weight. In conclusion, Clariscan improves short repetition time cardiac breathhold cine imaging, particularly in the long axis planes, with an optimal dose of 2 mg Fe/kg body weight.

Anomalous coronary arteries: anatomic and functional assessment by coronary and perfusion cardiovascular magnetic resonance in three sisters

Combined coronary and perfusion cardiovascular magnetic resonance was performed in three sisters with angina and suspected anomalous coronary arteries. Two sisters had anomalous coronary arteries passing between the aorta and right ventricular outflow tract and had abnormal myocardial perfusion. One sister had normal anatomy and perfusion. The combined approach identified the anatomy and functional significance of suspected anomalous coronary arteries.