The exonuclease TREX1 constitutes an innate immune checkpoint limiting cGAS/STING-mediated antitumor immunity.

The DNA exonuclease TREX1 (Three-prime repair exonuclease 1) is critical for preventing autoimmunity in mice and humans by degrading endogenous cytosolic DNA, which otherwise triggers activation of the innate cGAS/STING pathway leading to the production of type I IFNs. Since tumor cells are prone to aberrant cytosolic DNA accumulation, we hypothesized that they are critically dependent on TREX1 activity to limit their immunogenicity. Here we show, that in tumor cells TREX1 indeed restricts the spontaneous activation of the cGAS/STING pathway and the subsequent induction of a type I IFN response. As a result, TREX1 deficiency compromised in vivo tumor growth in mice. This delay depended on a functional immune system, systemic type I IFN signaling, and tumor-intrinsic cGAS expression. Mechanistically, we show that tumor TREX1 loss drove activation of CD8 T cells and NK cells, prevented CD8 T cell exhaustion, and remodeled an immunosuppressive myeloid compartment. Consequently, TREX1 deficiency synergized with T cell-directed immune checkpoint blockade. Collectively, we conclude that TREX1 is essential to limit tumor immunogenicity, and that targeting this innate immune checkpoint remodels the tumor microenvironment and enhances anti-tumor immunity by itself and in combination with T cell-targeted therapies.

Absolute Photoionization Cross Section and Dissociative Ionization Pathways of Alpha-Pinene.

The absolute photoionization cross section of the monoterpenoid, alpha-pinene (AP), is presented together with the relative photoionization cross sections of its dissociative fragments for the first time. Experiments are performed via multiplexed vacuum ultraviolet (VUV) synchrotron photoionization (PI) mass spectrometry in the 8.0-11.0 eV energy range. Experimental work is conducted at the Advanced Light Source of the Lawrence Berkeley National Laboratory. Dissociative fragments were identified at m/z 121, 94, 93, 92, and 80. The photoionization cross section for the parent mass at 11.0 eV was determined to be 17±4 Mb with a total ionization cross section of 92±23 Mb at the same photon energy. Experimental appearance energies of dissociative ionization fragments and potential dissociative ionization pathways calculated at the G4 level of theory are presented as well.

Risk prediction models for antineoplastic-associated cardiotoxicity in treatment of breast cancer: A systematic review.

PURPOSE: The objective of this systematic review is to assess methodology of published models to predict the risk of antineoplastic-associated cardiotoxicity in patients with breast cancer. METHODS: We searched PubMed and Embase for studies that developed or validated a multivariable risk prediction model. Data extraction and quality assessments were performed according to the Prediction Model Risk of Bias Assessment Tool (PROBAST). RESULTS: We identified 2,816 unique publications and included 8 eligible studies (7 new risk models and 1 validation of a risk stratification tool) that modeled risk with trastuzumab (n = 5), anthracyclines (n = 2), and anthracyclines with or without trastuzumab (n = 1). The most common final predictors were previous or concomitant chemotherapy (n = 5) and age (n = 4). Three studies incorporated measures of myocardial mechanics that may not be frequently available. Model discrimination was reported in 7 studies (range of area under the receiver operating characteristic curve, 0.56-0.88), while calibration was reported in 1 study. Internal and external validation were performed in 4 studies and 1 study, respectively. Using the PROBAST methodology, we rated the overall risk of bias as high for 7 of 8 studies and unclear for 1 study. Concerns for applicability were low for all studies. CONCLUSION: Among 8 models to predict the risk of cardiotoxicity of antineoplastic agents for breast cancer, 7 were rated as having a high risk of bias and all had low concerns for clinical applicability. Most evaluated studies reported positive measures of model performance but did not perform external validation. Efforts to improve development and reporting of these models to facilitate their use in practice are warranted.

Sodium-glucose cotransporter 2 inhibitors and cardiovascular clinical outcomes in acute heart failure: A narrative review.

PURPOSE: This review describes the evidence from randomized controlled trials (RCTs) regarding the effects of sodium-glucose cotransporter 2 (SGLT2) inhibitors on cardiovascular (CV) clinical outcomes when therapy is initiated during acute heart failure (HF). SUMMARY: SGLT2 inhibitors have become a cornerstone of guideline-directed medical therapy (GDMT) for type 2 diabetes mellitus, chronic kidney disease, and HF. Because of their ability to promote natriuresis and diuresis as well as other potentially beneficial CV effects, use of SGLT2 inhibitors has been investigated when therapy is initiated during hospitalization for acute HF. We identified 5 placebo-controlled RCTs that reported CV clinical outcomes incorporating one or more components of all-cause mortality, CV mortality, CV hospitalization, HF worsening, and hospitalization for HF in patients treated with empagliflozin (n = 3 trials), dapagliflozin (n = 1 trial), and sotagliflozin (n = 1 trial). Nearly all CV outcomes in these trials showed benefit with SGLT2 inhibitor use during acute HF. Incidence of hypotension, hypokalemia, and acute renal failure was generally similar to that with placebo. These findings are limited by heterogeneous outcome definitions, variation in time to SGLT2 inhibitor initiation, and small sample sizes. CONCLUSION: SGLT2 inhibitors may have a role in inpatient management of acute HF, provided there is close monitoring for fluctuations in hemodynamic, fluid, and electrolyte status. Initiation of SGLT2 inhibitors at the time of acute HF may promote optimized GDMT, continued medication adherence, and reduced risk of CV outcomes.

Predicting wildlife corridors for multiple species in an East African ungulate community.

Wildlife corridors are typically designed for single species, yet holistic conservation approaches require corridors suitable for multiple species. Modelling habitat linkages for wildlife is based on several modelling steps (each involving multiple choices), and in the case of multi-species corridors, an approach to optimize single species corridors to few or a single functional corridor for multiple species. To model robust corridors for multiple species and simultaneously evaluate the impact of methodological choices, we develop a multi-method approach to delineate corridors that effectively capture movement of multiple wildlife species, while limiting the area required. Using wildlife presence data collected along ground-based line transects between Lake Manyara and Tarangire National Parks, Tanzania, we assessed species-habitat association in both ensemble and stacked species distribution frameworks and used these to estimate linearly and non-linearly scaled landscape resistances for seven ungulate species. We evaluated habitat suitability and least-cost and circuit theory-based connectivity models for each species individually and generated a multi-species corridor. Our results revealed that species-habitat relationships and subsequent corridors differed across species, but the pattern of predicted landscape connectivity across the study area was similar for all seven species regardless of method (circuit theory or least-cost) and scaling of the habitat suitability-based cost surface (linear or non-linear). Stacked species distribution models were highly correlated with the seven species for all model outputs (r = 0.79 to 0.97), while having the greatest overlap with the individual species least-cost corridors (linear model: 61.6%; non-linear model: 60.2%). Zebra was the best single-species proxy for landscape connectivity. Overall, we show that multi-species corridors based on stacked species distribution models achieve relatively low cumulative costs for savanna ungulates as compared to their respective single-species corridors. Given the challenges and costs involved in acquiring data and parameterizing corridor models for multiple species, zebra may act as a suitable proxy species for ungulate corridor conservation in this system.

PICC versus midlines: Comparison of peripherally inserted central catheters and midline catheters with respect to incidence of thromboembolic and infectious complications.

INTRODUCTION: To decrease the complications related to central catheters there has been an increasing utilization of peripherally inserted central catheters (PICC) and ultrasound-guided long peripheral intravenous catheters (i.e. midlines). While the complications of PICC lines are well described there is less reported data on complications related to midline catheters. Our study aims are to compare the incidences of infectious and deep venous thrombosis (DVT) and sepsis related to PICCs and Midlines. METHODS: We performed a single-center retrospective review at an academic hospital. Data were collected on patients admitted between 1/1/2014-5/31/2016. Patient demographics, hospital length of stay (LOS), and ventilator days were collected. Outcomes of interest were line-related infections and thromboembolic events after the placement of these catheters. Endpoints were compared between three groups (PICC group, midline group and PICC placement followed by midline placement group). Univariate and multivariable analyses were used to compare across the three groups. RESULTS: The study included 3560 unique patients with 5058 catheters. There was an increase in use of midlines over the observed study period (245% increase from the end of 2015 to the middle of 2016). We found no significant differences in the rates of DVT among the three groups (PICC 4%, midline 3% and PICC-midline 4%; p = 0.12). There were no differences across the groups for sepsis (PICC 29%, midline 27%, and PICC-midline 32%; p = 0.14) or septic shock (PICC 7%, midline 8%, and PICC-midline 6%; p = 0.39). Adjusted means LOS were higher for patients with PICC lines compared to midlines, in both females and males. PICC group stayed longer, on average, on the ventilator compared to the midline group. No other significant differences were seen among groups. CONCLUSION: Increased utilization of midline catheters were not associated with decreased risk of DVT or sepsis when compared to peripherally inserted central catheters.

Novel Patient Metastatic Pleural Effusion-Derived Xenograft Model of Renal Medullary Carcinoma Demonstrates Therapeutic Efficacy of Sunitinib.

BACKGROUND: Renal medullary carcinoma (RMC) is a rare but aggressive tumor often complicated by early lung metastasis with few treatment options and very poor outcomes. There are currently no verified RMC patient-derived xenograft (PDX) mouse models established from metastatic pleural effusion (PE) available to study RMC and evaluate new therapeutic options. METHODS: Renal tumor tissue and malignant PE cells from an RMC patient were successfully engrafted into 20 NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) mice. We evaluated the histopathological similarity of the renal tumor and PE PDXs with the original patient renal tumor and PE, respectively. We then evaluated the molecular integrity of the renal tumor PDXs between passages, as well as the PE PDX compared to two generations of renal tumor PDXs, by microarray analysis. The therapeutic efficacy of sunitinib and temsirolimus was tested in a serially-transplanted generation of 27 PE PDX mice. RESULTS: The pathologic characteristics of the patient renal tumor and patient PE were retained in the PDXs. Gene expression profiling revealed high concordance between the two generations of renal tumor PDXs (RMC-P0 vs. RMC-P1, r=0.865), as well as between the first generation PE PDX and each generation of the renal tumor PDX (PE-P0 vs. RMC-P0, r=0.919 and PE-P0 vs. RMC-P1, r=0.843). A low number (626) of differentially-expressed genes (DEGs) was seen between the first generation PE PDX and the first generation renal tumor PDX. In the PE-P1 xenograft, sunitinib significantly reduced tumor growth (p<0.001) and prolonged survival (p=0.004) compared to the vehicle control. CONCLUSIONS: A metastatic PE-derived RMC PDX model was established and shown to maintain histologic features of the patient cancer. Molecular integrity of the PDX models was well maintained between renal tumor and PE PDX as well as between two successive renal tumor PDX generations. Using the PE PDX model, sunitinib demonstrated therapeutic efficacy for RMC. This model can serve as a foundation for future mechanistic and therapeutic studies for primary and metastatic RMC.

Strength of Recommendation and Quality of Evidence for Recommendations in Current Infectious Diseases Society of America Guidelines.

BACKGROUND: Grading of Recommendations Assessment, Development, and Evaluation (GRADE) is a systematic approach to grading strength of recommendation (SOR) and quality of evidence (QOE) for guideline recommendations. We aimed to assess the relationship between SOR and QOE in current Infectious Diseases Society of America (IDSA) guidelines. METHODS: In this cross-sectional analysis, we analyzed the frequency of SOR-QOE pairings, including discordance (defined as strong SOR based on expert opinion, very low, or low QOE) for GRADEd recommendations in IDSA guidelines published since 2010. Data for each recommendation were extracted on SOR, QOE, the domain of disease management (one or more of diagnosis, treatment, prevention, and other categories), and relevance to drug or nondrug treatment. RESULTS: Seventeen eligible guidelines provided 1042 unique GRADEd recommendations (n = 237, 711, 76, and 73 pertaining to diagnosis, treatment, prevention, and other domains, respectively; n = 574 and 137 pertaining to drug and nondrug treatment). Overall, the most common SOR was strong (71.8%; n = 748) and the most common QOE was low (48.6%; n = 506). Among all strong recommendations, 47.1% (n = 352) demonstrated discordance with QOE. By domain, strong recommendations were discordant in 36.6%, 51.4%, 29.3%, and 58.1% of recommendations pertaining to diagnosis, treatment, prevention, and other domains, respectively. Similarly, 50.7% and 54.0% of strong recommendations related to drug and nondrug treatment were discordant, respectively. We identified 39.6% of discordant recommendations to be consistent with good practice statements, which are recommended to be labeled as such without formal GRADEd designations of SOR or QOE. CONCLUSIONS: Among all IDSA guideline recommendations with strong SOR, approximately half were discordant with QOE, and this frequency varied across strata of domains of disease management.

pH-dependence of signaling-state formation in Drosophila cryptochrome.

Cryptochromes, FAD-dependent blue light photoreceptors, undergo a series of electron transfer reactions after light excitation. Time-resolved optical spectroscopy was employed to investigate the pH dependence of all light-dependent reactions in the cryptochrome from fruit flies. Signal state formation experiments on a time scale of seconds were found to be strongly pH dependent, and formation of both anionic and neutral FAD radicals could be detected, with reaction rates increasing by a factor of ~2.5 from basic to neutral pH values. Additionally, the influence of the amino acid His378 was investigated in further detail: Two protein variants, DmCry H378A and H378Q, showed significantly reduced rate constants for signal state formation, which again differed at neutral and alkaline pH values. Hence, His378 was identified as an amino acid responsible for the pronounced pH dependence; however, this amino acid can be excluded as a proton donor for the protonation of the anionic FAD radical. Other conserved amino acids appear to alter the overall polarity of the binding pocket and thus to be responsible for the pronounced pH dependence. Furthermore, the influence of pH and other experimental parameters, such as temperature, glycerol or ferricyanide concentrations, on the intermediately formed FAD-tryptophan radical pair was explored, which deprotonates on a microsecond time scale with a clear pH dependence, and subsequently recombines within milliseconds. Surprisingly, the latter reaction showed no pH dependence; potential reasons are discussed. All results are reviewed in terms of the photoreceptor and potential magnetoreceptor functions of Drosophila cryptochrome.

Why are they not accessing it? User barriers to clinical information access.

The Medical Library Association's InSight Initiative provides an open and collaborative environment for library and industry partners to discuss vexing problems and find solutions to better serve their users. The initiative's fifth summit, continuing work from the previous summit, focused on understanding how users discover and access information in the clinical environment. During the summit, participants were divided into working groups and encouraged to create a tangible product as a result of their discussions. At the end of the summit, participants established a framework for understanding users' pain points, discussed possible solutions to those points, and received feedback on their work from an End User Advisory Board comprising physicians, clinical researchers, and clinical faculty in biomedicine. In addition to the pain point framework, participants are developing MLA InSight Initiative Learning content with modules to educate librarians and publishers about critical aspects of user behavior. The 2020 Insight Initiative Fall Forum will serve as a virtual home for constructive dialogue between health sciences librarians and publishers on improving discovery and access to information.

Autoimmunity linked protein phosphatase PTPN22 as a target for cancer immunotherapy.

BACKGROUND: Cancer immunotherapy has evolved from interferon-alpha (IFNα) and interleukin-2 in the 1980s to CTLA-4 and PD-1/PD-L1 checkpoint inhibitors (CPIs), the latter highlighting the importance of enhancing T-cell functions. While the search for novel immunomodulatory pathways continues, combination therapies augmenting multiple pathways can also increase efficacy. The association of autoimmune-related adverse events with clinical efficacy following CPI treatment has been inferred and suggests that breaking tolerance thresholds associated with autoimmunity may affect host immune responses for effective cancer immunotherapy. RESULTS: Here, we show that loss of autoimmune associated PTPN22, a key desensitization node for multiple signaling pathways, including IFNα receptor (IFNAR) and T-cell receptor, can augment tumor responses. Implantation of syngeneic tumors in Ptpn22-/- mice led to expansion and activation of peripheral and intratumoral T cells and, in turn, spontaneous tumor regression as well as enhanced responses in combination with anti-PD-L1 treatment. Using genetically modified mice expressing a catalytically inactive PTPN22 or the autoimmunity-associated human single-nucleotide polymorphism variant, augmentation of antitumor immunity was dependent on PTPN22 phosphatase activity and partially on its adaptor functions. Further, antitumor responses were dependent on both CD4+ and CD8+T cells and, in part, IFNAR function. Finally, we demonstrate that the autoimmune susceptibility Ptpn22(C1858T) variant is associated with lower risk of developing non-melanoma skin cancers, improved overall survival and increased risk for development of hyperthyroidism or hypothyroidism following atezolizumab (anti-PD-L1) treatment. CONCLUSIONS: Together, these data suggest that inhibition of PTPN22 phosphatase activity may provide an effective therapeutic option for cancer immunotherapy and that exploring genetic variants that shift immune tolerance thresholds may serve as a paradigm for finding new cancer immunotherapy targets.

COLD REGULATED 27 and 28 are targets of CONSTITUTIVELY PHOTOMORPHOGENIC 1 and negatively affect phytochrome B signalling.

Phytochromes are red/far-red light receptors in plants involved in the regulation of growth and development. Phytochromes can sense the light environment and contribute to measuring day length; thereby, they allow plants to respond and adapt to changes in the ambient environment. Two well-characterized signalling pathways act downstream of phytochromes and link light perception to the regulation of gene expression. The CONSTITUTIVELY PHOTOMORPHOGENIC 1/SUPPRESSOR OF PHYA-105 (COP1/SPA) E3 ubiquitin ligase complex and the PHYTOCHROME INTERACTING FACTORs (PIFs) are key components of these pathways and repress light responses in the dark. In light-grown seedlings, phytochromes inhibit COP1/SPA and PIF activity and thereby promote light signalling. In a yeast-two-hybrid screen for proteins binding to light-activated phytochromes, we identified COLD-REGULATED GENE 27 (COR27). COR27 and its homologue COR28 bind to phyA and phyB, the two primary phytochromes in seed plants. COR27 and COR28 have been described previously with regard to a function in the regulation of freezing tolerance, flowering and the circadian clock. Here, we show that COR27 and COR28 repress early seedling development in blue, far-red and in particular red light. COR27 and COR28 contain a conserved Val-Pro (VP)-peptide motif, which mediates binding to the COP1/SPA complex. COR27 and COR28 are targeted for degradation by COP1/SPA and mutant versions with a VP to AA amino acid substitution in the VP-peptide motif are stabilized. Overall, our data suggest that COR27 and COR28 accumulate in light but act as negative regulators of light signalling during early seedling development, thereby preventing an exaggerated response to light.

Ultrasonography for Dorsal-Sided Wrist Pain in a Combat Environment: Technique, Pearls, and a Case Report of Dynamic Evaluation of the Scapholunate Ligament.

Ultrasonography is a commonly utilized tool in orthopedic surgery for the diagnosis and treatment of a variety of musculoskeletal conditions, including pathology about the wrist. Its value should not be underestimated when other diagnostic resources are unavailable - such as in a combat setting where ultrasounds, but not X-ray, are a standard equipment item. An active duty soldier presented to an orthopedic provider in an austere environment with chronic dorsal wrist pain due to a previous fall. Physical examination and dynamic ultrasound examination allowed the deployed provider to diagnose a scapholunate ligament injury. The patient was appropriately evacuated to a higher level of care without the need for X-ray or other advanced imaging modalities. Making this readily available resource a standard tool for providers deployed to a forward location could be beneficial for efficient and appropriate patient evacuation for musculoskeletal injuries. It can also rule out injuries that would otherwise have required unnecessary soldier movement through hostile territory for diagnostic tests such as X-rays. In addition, a simple technique and pearls for ultrasonography of the wrist are provided.

Novel Vasopressors in the Treatment of Vasodilatory Shock: A Systematic Review of Angiotensin II, Selepressin, and Terlipressin.

STUDY OBJECTIVE: Vasodilatory shock is the most common type of shock. Catecholamine vasopressors are the cornerstone of hemodynamic therapy but carry risks. Angiotensin II (AT2) was recently approved, and other novel agents (selepressin and terlipressin) are under investigation and used outside the United States (terlipressin). We performed a systematic review to summarize the efficacy and safety of these novel vasopressors and to offer guidance on their appropriate use. DESIGN: Systematic review of controlled trials. METHODS: Numerous databases were searched using terms related to angiotensin II, selepressin, terlipressin, vasopressor, and shock. Twenty-one citations, including 16 prospective comparative trials and 5 post hoc analyses reporting effects of AT2, selepressin, and terlipressin, were reviewed for data on outcomes related to hemodynamic measures, mortality, severity and duration of illness, concomitant vasopressor utilization, and adverse effects. Findings from eligible literature are described qualitatively using Cochrane methods. RESULTS: Fourteen controlled trials were assessed after exclusion of 2 dated trials of a distinct AT2 formulation. Trials are limited for AT2 (n = 2) and selepressin (n = 1), while terlipressin was investigated in 11 small trials. Overall, the trials have an unclear risk of bias. Most report mean arterial pressure (MAP) as primary end point, and all indicate novel vasopressors increase MAP compared to placebo and to a similar degree as with catecholamine vasopressors. Mortality findings are preliminary, as they have been limited to specific subgroups in trials of terlipressin and post hoc analyses of one trial of AT2. Trials reported safety concerns for each agent including thromboembolism with AT2 and ischemia with terlipressin/selepressin. CONCLUSION: In this systematic review, controlled trials of novel vasopressors in treatment of vasodilatory shock were limited and of low quality. Angiotensin II, selepressin, and terlipressin appear to significantly increase MAP, but further study is required, particularly for selepressin, to determine their safety, efficacy, and role in treatment of vasodilatory shock.

Photoactivation of Drosophila melanogaster cryptochrome through sequential conformational transitions.

Cryptochromes are blue-light photoreceptor proteins, which provide input to circadian clocks. The cryptochrome from Drosophila melanogaster (DmCry) modulates the degradation of Timeless and itself. It is unclear how light absorption by the chromophore and the subsequent redox reactions trigger these events. Here, we use nano- to millisecond time-resolved x-ray solution scattering to reveal the light-activated conformational changes in DmCry and the related (6-4) photolyase. DmCry undergoes a series of structural changes, culminating in the release of the carboxyl-terminal tail (CTT). The photolyase has a simpler structural response. We find that the CTT release in DmCry depends on pH. Mutation of a conserved histidine, important for the biochemical activity of DmCry, does not affect transduction of the structural signal to the CTT. Instead, molecular dynamics simulations suggest that it stabilizes the CTT in the resting-state conformation. Our structural photocycle unravels the first molecular events of signal transduction in an animal cryptochrome.

Role of angiotensin II in treatment of refractory distributive shock.

OBJECTIVE: Clinical data and gaps in knowledge regarding angiotensin II (AT2), which was approved by the Food and Drug Administration in December 2017 via priority review for treatment of septic and other vasodilatory shock, is discussed. SUMMARY: AT2 is an endogenous peptide that raises blood pressure via vasoconstriction and increased aldosterone release. It was previously available but withdrawn from the US market; previous low-quality research describes increases in mean arterial pressure (MAP). The recent approval of AT2 was based on data from a Phase III randomized trial comparing i.v. AT2 (n = 163) with placebo use (n = 158) in patients with vasodilatory shock receiving high doses of other vasopressors. AT2 significantly increased achievement of the primary endpoint, MAP response at 3 hours after the start of infusion, relative to placebo use (69.9% [n = 114] versus 23.4% [n = 37], p < 0.0001). Serious adverse events occurred in 60.7% (n = 99) and 67.1% (n = 106) of patients treated with AT2 and placebo recipients, respectively, including venous and arterial thromboembolic events (12.9% [n = 21] and 5.1% [n = 8], respectively). No significant effects of AT2 on 7- or 28-day mortality were seen among all patients in the ATHOS-3 trial. However, post hoc analyses suggested that AT2 may reduce mortality in patients with low baseline AT2 levels, exaggerated response to AT2, and acute kidney injury receiving concomitant renal replacement therapy. Overall, due to shortcomings of the ATHOS-3 trial data and the absence of confirmatory studies, the optimal place in therapy of AT2 for vasodilatory shock cannot be determined with confidence. CONCLUSION: Intravenous AT2 represents a novel treatment strategy for refractory septic or other vasodilatory shock, although findings of safety and efficacy have not been replicated and the drug's optimal place in therapy is uncertain.

Coexpression of Inhibitory Receptors Enriches for Activated and Functional CD8+ T Cells in Murine Syngeneic Tumor Models.

Exhausted T cells have been described in cancer patients and murine tumor models largely based on their expression of various inhibitory receptors. Understanding of the functional attributes of these cells is limited. Here, we report that among CD8+ T cells in commonly used syngeneic tumor models, the coexpression of inhibitory receptors PD-1, LAG3, and TIM3 defined a group of highly activated and functional effector cells. Coexpression of these receptors further enriched for antigen-specific cells with increased T-cell receptor clonality. Anti-PD-L1 treatment increased the number and activation of these triple-positive CD8+ T cells without affecting the density of PD-1- cells. The intratumoral density of CD8+ T cells coexpressing inhibitory receptors negatively correlated with tumor burden. The density ratio and pretreatment phenotype of CD8+ T cells coexpressing inhibitory receptors was positively correlated with response across a variety of tumor models. Our results demonstrate that coexpression of inhibitory receptors is not a signifier of exhausted T cells, but rather can define a group of activated and functional effector cells in syngeneic tumor models. In the cancer setting, these cells could represent a heterogeneous population of not only exhausted but also highly activated cells responsive to treatment.

Anti-PD-L1 Treatment Results in Functional Remodeling of the Macrophage Compartment.

Checkpoint inhibitors like anti-PD1/PD-L1 have demonstrated significant therapeutic efficacy in a subset of patients partly through reinvigoration of CD8 T cells. However, their impact on myeloid cells remains largely unknown. Here, we report that anti-PD-L1 treatment favorably impacts the phenotype and function of tumor macrophages by polarizing the macrophage compartment toward a more proinflammatory phenotype. This phenotype was characterized by a decrease in Arginase-I (ARG1) expression and an increase in iNOS, MHCII, and CD40 expression. Whole-transcriptome profiling further confirmed extensive polarization of both tumor monocytes and macrophages from a suppressive to a proinflammatory, immunostimulatory phenotype. This polarization was driven mainly through IFNγ and was associated with enhanced T-cell activity. Transfer of monocytes into anti-PD-L1-treated tumor-bearing mice led to macrophage differentiation into a more proinflammatory phenotype, with an increase in CD8 T cells expressing granzyme-B and an increase in the CD8/Treg ratio compared with control-treated mice. Although in responsive tumor models, anti-PD-L1 treatment remodeled the macrophage compartment with beneficial effects on T cells, both macrophage reprogramming and depletion were needed to maximize anti-PD-L1 responses in a tumor immune contexture with high macrophage burden. Our results demonstrate that anti-PD-L1 treatment can favorably remodel the macrophage compartment in responsive tumor models toward a more proinflammatory phenotype, mainly through increased IFNγ levels. They also suggest that directly targeting these cells with reprogramming and depleting agents may further augment the breadth and depth of response to anti-PD-L1 treatment in less responsive or more macrophage-dense tumor microenvironments. SIGNIFICANCE: This work demonstrates that increased IFNγ signaling following anti-PD-L1 treatment can remodel the macrophage compartment to enhance T-cell responses.Graphical Abstract: http://cancerres.aacrjournals.org/content/canres/79/7/1493/F1.large.jpg.