Dissecting the Mechanisms Underlying the Cytokine Release Syndrome (CRS) Mediated by T-Cell Bispecific Antibodies

PURPOSE

Target-dependent TCB activity can result in the strong and systemic release of cytokines that may develop into cytokine release syndrome (CRS), highlighting the need to understand and prevent this complex clinical syndrome.

EXPERIMENTAL DESIGN

We explored the cellular and molecular players involved in TCB-mediated cytokine release by single-cell RNA-sequencing of whole blood treated with CD20-TCB together with bulk RNA-sequencing of endothelial cells exposed to TCB-induced cytokine release. We used the in vitro whole blood assay and an in vivo DLBCL model in immunocompetent humanized mice to assess the effects of dexamethasone, anti-TNFα, anti-IL6R, anti-IL1R, and inflammasome inhibition, on TCB-mediated cytokine release and antitumor activity.

RESULTS

Activated T cells release TNFα, IFNγ, IL2, IL8, and MIP-1β, which rapidly activate monocytes, neutrophils, DCs, and NKs along with surrounding T cells to amplify the cascade further, leading to TNFα, IL8, IL6, IL1β, MCP-1, MIP-1α, MIP-1β, and IP-10 release. Endothelial cells contribute to IL6 and IL1β release and at the same time release several chemokines (MCP-1, IP-10, MIP-1α, and MIP-1β). Dexamethasone and TNFα blockade efficiently reduced CD20-TCB-mediated cytokine release whereas IL6R blockade, inflammasome inhibition, and IL1R blockade induced a less pronounced effect. Dexamethasone, IL6R blockade, IL1R blockade, and the inflammasome inhibitor did not interfere with CD20-TCB activity, in contrast to TNFα blockade, which partially inhibited antitumor activity.

CONCLUSIONS

Our work sheds new light on the cellular and molecular players involved in cytokine release driven by TCBs and provides a rationale for the prevention of CRS in patients treated with TCBs. See related commentary by Luri-Rey et al., p. 4320.

Elevated and sustained anti-feeding effect of Scalibor® deltamethrin collar against the sand fly Phlebotomus perniciosus in dogs confirmed for 1 year following treatment

Dogs are reservoir hosts for Leishmania infantum, a protozoan parasite transmitted by phlebotomine sand flies. The anti-feeding and fast-killing efficacy of Scalibor® deltamethrin collars against experimental Phlebotomus perniciosus challenges on dogs was determined over 1 year. Two groups of 8 dogs each were fitted with placebo (control) or deltamethrin collars (treated) on Day 0 and exposed to sand flies approximately every 28 days up to Day 364. After each exposure, anti-feeding and fast-killing efficacy rates were determined by comparing blood-fed or live insects, respectively, in the treated vs. the control group. Blood-fed and live sand flies were significantly less in treated dogs as compared to control dogs at each assessment. The anti-feeding efficacy rate exceeded 90% except on Day 337 (89%) but increased again (96%) on Day 364. Fast killing efficacy was <74% over the study when considering all flies. However, this value increased cumulatively to 98% when only blood-fed flies were compared between groups. Scalibor® collars are highly effective at preventing P. perniciosus blood-feeding and in fast-killing flies taking a blood meal for up to 1 year after application. These strong and long-lasting effects are an important strategic component for L. infantum transmission control.

Laboratory evidence that dinotefuran, pyriproxyfen and permethrin combination abrogates Leishmania infantum transmissibility by sick dogs

Dogs are reservoir hosts of leishmaniasis caused by Leishmania infantum and transmitted by phlebotomine vectors. The effect of dinotefuran, pyriproxyfen and permethrin spot-on solution (Vectra®3D, Ceva Santé Animale, Libourne, France) on Leishmania transmissibility by naturally infected dogs via reared Phlebotomus perniciosus, was assessed. Dogs affected by leishmaniasis were submitted to xenodiagnosis and 6 infecting >10% of insects were treated topically on day 0. Antifeeding, insecticidal and anti-transmissibility effects were evaluated through xenodiagnoses performed on days 1, 7 and 28, using individual pre-treatment parameters as control. Feeding and mortality rates were assessed at 24 h, whereas promastigote infection, maturation and burden were assessed up to 96 h post blood meal (potentially infectious rate). On day 1, the anti-feeding efficacy was >95% in 4 dogs, insecticidal efficacy 100% in 4 dogs, and anti-transmissibility effect 100% in 6 dogs. Efficacy rates recorded on day 7 were very similar to day 1. On day 28, anti-feeding and insecticidal efficacy values were much broader, ranging 32.6-100% and 7.7-94.4%, respectively. Potentially infectious insects were recorded from two dogs, with sharp decrease in transmissibility rate as compared with pre-treatment condition. Altogether, Vectra®3D abrogated by >98% the potential Leishmania transmissibility by the examined pool of infected dogs over 1 month.

Myocardial work evaluation in patients with severe aortic stenosis undergoing transcatheter aortic valve implantation

Funding Acknowledgements

Type of funding sources: None.

Background

myocardial work (MW) is a novel echocardiographic technique which assesses left ventricular (LV) performance through LV pressure-strain loops. MW corrects speckle tracking echocardiography (STE)-derived parameters for afterload using non-invasive systolic blood pressure (SBP) as a surrogate for LV systolic pressure. In patients with severe aortic stenosis (AS), the corrected MW (cMW) has been proposed, consisting in adding the mean aortic gradient in SBP. This method revealed to be feasible and reliable, demonstrating good correlation with invasively measured LV systolic pressure.

Purpose

to evaluate myocardial performance of patients with severe AS, before and after transcatheter aortic valve implantation (TAVI), by MW indices.

Methods

patients with severe AS undergoing TAVI were included. Transthoracic, standard echocardiography and STE were performed the day before the procedure and within 2 days after. MW was calculated by combining STE-derived indices with non-invasively estimated LV systolic pressure.

Results

30 patients (79 ± 5 years old, 56% females) with severe AS (mean gradient 47 ± 14 mmHg, aortic valve area 0.6 ± 0.1 cm2), and eligible for TAVI were enrolled. Baseline global longitudinal strain was impaired (GLS -15 ± 4%), in presence of normal LV ejection fraction (LVEF 57 ± 10%). Corrected global work index and global constructive work were preserved at baseline and markedly decreased after TAVI (cGWI 2322 ± 791 vs 1710 ± 505 mmHg%, p = 0.001; cGCW 2774 ± 803 vs 2083 ± 536 mmHg%, p = 0.0007). Corrected global wasted work and global work efficiency were higher than reference values existing in literature, and no significant changes were observed after TAVI (cGWW 276 ± 174 vs 277 ± 165 mmHg%, p = 0.974; cGWE 89 ± 5 vs 87 ± 5%, p = 0.177). A significant inverse correlation was found between baseline cGWI and left atrial volume index (r=-0.5, p = 0.03).

Conclusions

patients with severe aortic stenosis and preserved LVEF show a good LV performance before and after TAVI, with a significant decrease in MW indices after TAVI, because of the reduced afterload due to AS treatment. The negative correlation between left atrial volume and cGWI may reflect the extent of myocardial damage in AS. However, further studies with larger sample size and appropriate follow-up are needed to evaluate the role of MW in prognosis and risk stratification of this subset of patients.

A novel nomogram predicting lymph node invasion among patients with prostate cancer: The importance of extracapsular extension at multiparametric magnetic resonance imaging

PURPOSE

To develop a novel risk tool that allows the prediction of lymph node invasion (LNI) among patients with prostate cancer (PCa) treated with robot-assisted radical prostatectomy (RARP) and extended pelvic lymph node dissection (ePLND).

METHODS

We retrospectively identified 742 patients treated with RARP + ePLND at a single center between 2012 and 2018. All patients underwent multiparametric magnetic resonance imaging (mpMRI) and were diagnosed with targeted biopsies. First, the nomogram published by Briganti et al. was validated in our cohort. Second, three novel multivariable logistic regression models predicting LNI were developed: (1) a complete model fitted with PSA, ISUP grade groups, percentage of positive cores (PCP), extracapsular extension (ECE), and Prostate Imaging Reporting and Data System (PI-RADS) score; (2) a simplified model where ECE score was not included (model 1); and (3) a simplified model where PI-RADS score was not included (model 2). The predictive accuracy of the models was assessed with the receiver operating characteristic-derived area under the curve (AUC). Calibration plots and decision curve analyses were used.

RESULTS

Overall, 149 patients (20%) had LNI. In multivariable logistic regression models, PSA (OR: 1.03; P= 0.001), ISUP grade groups (OR: 1.33; P= 0.001), PCP (OR: 1.01; P= 0.01), and ECE score (ECE 4 vs. 3 OR: 2.99; ECE 5 vs. 3 OR: 6.97; P< 0.001) were associated with higher rates of LNI. The AUC of the Briganti et al. model was 74%. Conversely, the AUC of model 1 vs. model 2 vs. complete model was, respectively, 78% vs. 81% vs. 81%. Simplified model 1 (ECE score only) was then chosen as the best performing model. A nomogram to calculate the individual probability of LNI, based on model 1 was created. Setting our cut-off at 5% we missed only 2.6% of LNI patients.

CONCLUSIONS

We developed a novel nomogram that combines PSA, ISUP grade groups, PCP, and mpMRI-derived ECE score to predict the probability of LNI at final pathology in RARP candidates. The application of a nomogram derived cut-off of 5% allows to avoid a consistent number of ePLND procedures, missing only 2.6% of LNI patients. External validation of our model is needed.

Class IA PI3Ks regulate subcellular and functional dynamics of IDO1

Knowledge of a protein's spatial dynamics at the subcellular level is key to understanding its function(s), interactions, and associated intracellular events. Indoleamine 2,3-dioxygenase 1 (IDO1) is a cytosolic enzyme that controls immune responses via tryptophan metabolism, mainly through its enzymic activity. When phosphorylated, however, IDO1 acts as a signaling molecule in plasmacytoid dendritic cells (pDCs), thus activating genomic effects, ultimately leading to long-lasting immunosuppression. Whether the two activities-namely, the catalytic and signaling functions-are spatially segregated has been unclear. We found that, under conditions favoring signaling rather than catabolic events, IDO1 shifts from the cytosol to early endosomes. The event requires interaction with class IA phosphoinositide 3-kinases (PI3Ks), which become activated, resulting in full expression of the immunoregulatory phenotype in vivo in pDCs as resulting from IDO1-dependent signaling events. Thus, IDO1's spatial dynamics meet the needs for short-acting as well as durable mechanisms of immune suppression, both under acute and chronic inflammatory conditions. These data expand the theoretical basis for an IDO1-centered therapy in inflammation and autoimmunity.

Antiangiogenic immunotherapy suppresses desmoplastic and chemoresistant intestinal tumors in mice

Mutations in APC promote colorectal cancer (CRC) progression through uncontrolled WNT signaling. Patients with desmoplastic CRC have a significantly worse prognosis and do not benefit from chemotherapy, but the mechanisms underlying the differential responses of APC-mutant CRCs to chemotherapy are not well understood. We report that expression of the transcription factor prospero homeobox 1 (PROX1) was reduced in desmoplastic APC-mutant human CRCs. In genetic Apc-mutant mouse models, loss of Prox1 promoted the growth of desmoplastic, angiogenic, and immunologically silent tumors through derepression of Mmp14. Although chemotherapy inhibited Prox1-proficient tumors, it promoted further stromal activation, angiogenesis, and invasion in Prox1-deficient tumors. Blockade of vascular endothelial growth factor A (VEGFA) and angiopoietin-2 (ANGPT2) combined with CD40 agonistic antibodies promoted antiangiogenic and immunostimulatory reprogramming of Prox1-deficient tumors, destroyed tumor fibrosis, and unleashed T cell-mediated killing of cancer cells. These results pinpoint the mechanistic basis of chemotherapy-induced hyperprogression and illustrate a therapeutic strategy for chemoresistant and desmoplastic CRCs.

A single oral dose of fluralaner (Bravecto®) in dogs rapidly kills 100% of blood-fed Phlebotomus perniciosus, a main visceral leishmaniasis vector, for at least 1 month after treatment

Dogs are the reservoir host of zoonotic visceral leishmaniasis (VL) caused by Leishmania infantum (Kinetoplastida: Trypanosomatidae). Both subclinically-infected and sick animals can be infectious to competent phlebotomine vectors. The degree and duration of insecticidal efficacy of an oral dose of fluralaner (Bravecto®; Merck Animal Health) was determined in dogs exposed to bites of Phlebotomus perniciosus (Diptera: Psychodidae), a main Mediterranean vector of VL. Twelve dogs allocated to two groups of six animals each were included in a parallel-group designed, negative-controlled, randomized, blinded, single-centre efficacy study. Group 2 was treated with fluralaner on day 0, and sand-fly exposure of both groups was performed on days 1, 28 and 84. Viability of blood-fed females was assessed up to 96 h after exposure and efficacy was measured as the survival rate of specimens fed on Group 2 versus those fed on Group 1. A mortality of 100% was recorded at 24 h in females fed on Group 2 at both days 1 and 28. Significant insecticidal efficacy was still observed on day 84, with > 50% mortality recorded by 48 h post blood meal in Group 2. Fluralaner treatment of dogs represents a promising and affordable method for reducing the pool of infected vectors in endemic settings of zoonotic VL.

Burnout, depression and paranoid ideation: a cluster-analytic study

Background

A link between burnout and paranoid ideation has long been suspected. However, systematic research on the association has been scarce.

Aims

We investigated the relationship between burnout and paranoid ideation. Because burnout overlaps with depression, depression was also examined.

Methods

A total of 218 Swiss schoolteachers participated in the study (58% female; mean age: 47). Burnout symptoms were assessed with the emotional exhaustion (EE) and depersonalization (DP) subscales of the Maslach Burnout Inventory-Educators Survey, depressive symptoms with the PHQ-9 and paranoid ideation with the Green et al. Paranoid Thought Scales.

Results

Burnout, depression and their subdimensions showed raw correlations ranging from 0.42 to 0.55 with paranoid ideation. Burnout, depression and paranoid thoughts were found to cluster together. Lower levels of burnout and depression coexisted with lower levels of paranoid ideation and higher levels of burnout and depression coexisted with higher levels of paranoid ideation. When corrected for measurement error, the correlations of EE with depression and DP were 0.96 and 0.57, respectively. A principal component analysis confirmed that EE was indistinguishable from depression.

Conclusions

Burnout is substantially associated with paranoid ideation. Interestingly, EE correlated as strongly with paranoid ideation as it correlated with DP. Moreover, if burnout is a syndrome of EE and DP that excludes depression, then the EE-depression correlation should not be close to 1 and EE should not correlate more strongly with depression than with DP. These basic requirements for construct distinctiveness and syndromal unity were not satisfied.

Engagement of Nuclear Coactivator 7 by 3-Hydroxyanthranilic Acid Enhances Activation of Aryl Hydrocarbon Receptor in Immunoregulatory Dendritic Cells

Indoleamine 2,3-dioxygenase 1 (IDO1) catalyzes the first step in the kynurenine pathway of tryptophan (Trp) degradation that produces several biologically active Trp metabolites. L-kynurenine (Kyn), the first byproduct by IDO1, promotes immunoregulatory effects via activation of the Aryl hydrocarbon Receptor (AhR) in dendritic cells (DCs) and T lymphocytes. We here identified the nuclear coactivator 7 (NCOA7) as a molecular target of 3-hydroxyanthranilic acid (3-HAA), a Trp metabolite produced downstream of Kyn along the kynurenine pathway. In cells overexpressing NCOA7 and AhR, the presence of 3-HAA increased the association of the two molecules and enhanced Kyn-driven, AhR-dependent gene transcription. Physiologically, conventional (cDCs) but not plasmacytoid DCs or other immune cells expressed high levels of NCOA7. In cocultures of CD4⁺ T cells with cDCs, the co-addition of Kyn and 3-HAA significantly increased the induction of Foxp3⁺ regulatory T cells and the production of immunosuppressive transforming growth factor β in an NCOA7-dependent fashion. Thus, the co-presence of NCOA7 and the Trp metabolite 3-HAA can selectively enhance the activation of ubiquitary AhR in cDCs and consequent immunoregulatory effects. Because NCOA7 is often overexpressed and/or mutated in tumor microenvironments, our current data may provide evidence for a new immune check-point mechanism based on Trp metabolism and AhR.

Preclinical discovery and development of fingolimod for the treatment of multiple sclerosis

Introduction: Fingolimod, the first oral disease-modifying treatment (DMT) in multiple sclerosis (MS), is a sphingosine 1-phosphate receptor (S1PR) ligand. Approved in 2010, fingolimod has been extensively studied and has been credited with several mechanisms of actions that contribute to its efficacy in MS, among which is the regulation of lymphocyte circulation between the central nervous system and the periphery. Concerns about toxicity, off-target effects, and real-life performance have been raised over time in post-marketing studies of such that next-generation sphingosine-1 phosphate receptor ligands are now being developed. Areas covered: Herein, the authors expand upon previous systematic reviews obtained via PubMed and through their expert opinion on fingolimod use in clinical practice. Long-term data including long-term efficacy, safety, tolerability, and management especially within growing DMT options and pre-treatment constellation in MS patients are discussed, together with the results of an increased understanding of the chemistry underlying the structure-activity relationship. Expert opinion: Despite the limitations illustrated in this article, fingolimod still constitutes a paradigm shift in MS treatment. However, although immunomodulation via S1PRs on lymphocytes has represented a major breakthrough in the clinical management of MS, modifying the evolution of progressive MS will likely require the development of approaches other than merely targeting S1PRs.

IL-35Ig-expressing dendritic cells induce tolerance via Arginase 1

The cytokine interleukin IL‐35 is known to exert strong immunosuppressive functions. Indoleamine 2,3‐dioxygenase 1 (IDO1) and Arginase 1 (Arg1) are metabolic enzymes that, expressed by dendritic cells (DCs), contribute to immunoregulation. Here, we explored any possible link between IL‐35 and the activity of those enzymes. We transfected a single chain IL‐35Ig gene construct in murine splenic DCs (DC₃₅) and assessed any IDO1 and Arg1 activities as resulting from ectopic IL‐35Ig expression, both in vitro and in vivo. Unlike Ido1, Arg1 expression was induced in vitro in DC₃₅, and it conferred an immunosuppressive phenotype on those cells, as revealed by a delayed‐type hypersensitivity assay. Moreover, the in vivo onset of a tolerogenic phenotype in DC₃₅ was associated with the detection of CD25⁺CD39⁺, rather than Foxp3⁺, regulatory T cells. Therefore, Arg1, but not Ido1, expression in DC₃₅ appears to be an early event in IL‐35Ig–mediated immunosuppression.

CD20-TCB with Obinutuzumab Pretreatment as Next-Generation Treatment of Hematologic Malignancies

Purpose: Despite promising clinical activity, T-cell-engaging therapies including T-cell bispecific antibodies (TCB) are associated with severe side effects requiring the use of step-up-dosing (SUD) regimens to mitigate safety. Here, we present a next-generation CD20-targeting TCB (CD20-TCB) with significantly higher potency and a novel approach enabling safer administration of such potent drug.Experimental Design: We developed CD20-TCB based on the 2:1 TCB molecular format and characterized its activity preclinically. We also applied a single administration of obinutuzumab (Gazyva pretreatment, Gpt; Genentech/Roche) prior to the first infusion of CD20-TCB as a way to safely administer such a potent drug.Results: CD20-TCB is associated with a long half-life and high potency enabled by high-avidity bivalent binding to CD20 and head-to-tail orientation of B- and T-cell-binding domains in a 2:1 molecular format. CD20-TCB displays considerably higher potency than other CD20-TCB antibodies in clinical development and is efficacious on tumor cells expressing low levels of CD20. CD20-TCB also displays potent activity in primary tumor samples with low effector:target ratios. In vivo, CD20-TCB regresses established tumors of aggressive lymphoma models. Gpt enables profound B-cell depletion in peripheral blood and secondary lymphoid organs and reduces T-cell activation and cytokine release in the peripheral blood, thus increasing the safety of CD20-TCB administration. Gpt is more efficacious and safer than SUD.Conclusions: CD20-TCB and Gpt represent a potent and safer approach for treatment of lymphoma patients and are currently being evaluated in phase I, multicenter study in patients with relapsed/refractory non-Hodgkin lymphoma (NCT03075696). Clin Cancer Res; 24(19); 4785-97. ©2018 AACR See related commentary by Prakash and Diefenbach, p. 4631.

Detection of Melanoma Cells in Peripheral Blood and Sentinel Lymph Nodes by RT-PCR Analysis: A Comparative Study with Immunohistochemistry

The presence of lymph node metastases is the best prognostic factor for predicting relapse or survival in melanoma patients. It has been demonstrated that melanoma metastases spread through the first lymph node(s) draining the tumor (sentinel lymph node, SN) to the lymphatic system and that detection of melanoma cells in peripheral blood directly correlates with prognosis in melanoma.

To identify lymph node metastases and circulating melanocytes, we developed a single-step reverse transcriptase-polymerase chain reaction assay (RT-PCR) for detection of two melanoma-specific markers: the tyrosinase gene, which encodes an enzyme associated with melanin synthesis, and melanoma antigen-related T-cells, which are present in tumor infiltrating T-lymphocytes. This method detects two tumor cells in a background of 107 lymphocytes.

Thirty patients with stage I–IV cutaneous melanoma entered the study. Blood samples were taken preoperatively, one month after excision of the primary melanoma lesion and the SN or total lymphadenectomy, and before the start of chemotherapy and every three months thereafter in metastatic patients. SNs were collected from 22 patients, bisected and analyzed by RT-PCR and routine pathological and immunohistochemical tests. The preliminary results indicate that RT-PCR for melanoma markers is a sensitive and valuable method for the detection of micrometastases and for early diagnosis and staging of melanoma.

Gamma Probe-Guided Thoracoscopic Surgery of Small Pulmonary Nodules

Video-assisted thoracic surgery (VATS) is an interesting and emerging procedure for the diagnosis and treatment of peripheral pulmonary nodules. We developed a new radioguided surgical technique for the detection during VATS of pulmonary nodules smaller than 2 cm, situated deep in the lung parenchyma and neither visible nor palpable with endoscopic instruments. The procedure is divided into two phases. Two hours before surgery 0.3 ml of a solution composed of 0.2 mL of 99mTc-labeled human serum albumin microspheres (5–10 MBq) and 0.1 mL of non-ionic contrast is injected into the lesion under CT guidance. Then the patient is submitted to VATS. During thoracoscopy a collimated probe of 11 mm diameter connected to a gamma ray detector is introduced via an 11.5 mm trocar and the pleural surface of the suspected area is scanned. A hot spot indicates the presence of the radiolabeled nodule and hence the area to be resected. We treated 39 patients with small pulmonary nodules (mean size, 8.3 mm; range, 4–19 mm). The patients were 27 men and 12 women (mean age, 60.8 years; range, 13–80 years). Nineteen patients had a history of synchronous or metachronous malignancy. In all cases the nodule was detected and resected and the resection margins were pathologically free of tumor. Histological examination showed 21 benign and 18 malignant lesions (7 metastases and 11 primary lung cancers). Nine patients with a frozen section-based histopathological diagnosis of lung cancer without functional contraindications underwent a completion lobectomy by open surgery in the same surgical session. In conclusion, the radiolocalization of small pulmonary nodules by gamma probe during VATS is a safe and easy procedure, with fewer complications and a lower failure rate than other localization techniques.

Deficiency of immunoregulatory indoleamine 2,3-dioxygenase 1in juvenile diabetes

A defect in indoleamine 2,3-dioxygenase 1 (IDO1), which is responsible for immunoregulatory tryptophan catabolism, impairs development of immune tolerance to autoantigens in NOD mice, a model for human autoimmune type 1 diabetes (T1D). Whether IDO1 function is also defective in T1D is still unknown. We investigated IDO1 function in sera and peripheral blood mononuclear cells (PBMCs) from children with T1D and matched controls. These children were further included in a discovery study to identify SNPs in IDO1 that might modify the risk of T1D. T1D in children was characterized by a remarkable defect in IDO1 function. A common haplotype, associated with dysfunctional IDO1, increased the risk of developing T1D in the discovery and also confirmation studies. In T1D patients sharing such a common IDO1 haplotype, incubation of PBMCs in vitro with tocilizumab (TCZ) - an IL-6 receptor blocker - would, however, rescue IDO1 activity. In an experimental setting with diabetic NOD mice, TCZ was found to restore normoglycemia via IDO1-dependent mechanisms. Thus, functional SNPs of IDO1 are associated with defective tryptophan catabolism in human T1D, and maneuvers aimed at restoring IDO1 function would be therapeutically effective in at least a subgroup of T1D pediatric patients.

Lymphatic endothelial cells attenuate inflammation via suppression of dendritic cell maturation

Vascular endothelial growth factor-C (VEGF-C)-induced lymphangiogenesis and increased tissue drainage have been reported to inhibit acute and chronic inflammation, and an activated lymphatic endothelium might mediate peripheral tolerance. Using transgenic mice overexpressing VEGF-C in the skin, we found that under inflammatory conditions, VEGF-C-mediated expansion of the cutaneous lymphatic network establishes an immune-inhibitory microenvironment characterised by increased regulatory T (Treg) cells, immature CD11c+CD11b+ dendritic cells (DCs) and CD8+ cells exhibiting decreased effector function. Strikingly, lymphatic endothelial cell (LEC)-conditioned media (CM) potently suppress DC maturation with reduced expression of MHCII, CD40, and IL-6, and increased IL-10 and CCL2 expression. We identify an imbalance in prostaglandin synthase expression after LEC activation, favoring anti-inflammatory prostacyclin synthesis. Importantly, blockade of LEC prostaglandin synthesis partially restores DC maturity. LECs also produce TGF-ß1, contributing to the immune-inhibitory microenvironment. This study identifies novel mechanisms by which the lymphatic endothelium modulates cellular immune responses to limit inflammation.

Oxidative stress-induced S100B accumulation converts myoblasts into brown adipocytes via an NF-κB/YY1/miR-133 axis and NF-κB/YY1/BMP-7 axis

Muscles of sarcopenic people show hypotrophic myofibers and infiltration with adipose and, at later stages, fibrotic tissue. The origin of infiltrating adipocytes resides in fibro-adipogenic precursors and nonmyogenic mesenchymal progenitor cells, and in satellite cells, the adult stem cells of skeletal muscles. Myoblasts and brown adipocytes share a common Myf5⁺ progenitor cell: the cell fate depends on levels of bone morphogenetic protein 7 (BMP-7), a TGF-β family member. S100B, a Ca²⁺-binding protein of the EF-hand type, is expressed at relatively high levels in myoblasts from sarcopenic humans and exerts anti-myogenic effects via NF-κB-dependent inhibition of MyoD, a myogenic transcription factor acting upstream of the essential myogenic factor, myogenin. Adipogenesis requires high levels of ROS, and myoblasts of sarcopenic subjects show elevated ROS levels. Here we show that: (1) ROS overproduction in myoblasts results in upregulation of S100B levels via NF-κB activation; and (2) ROS/NF-κB-induced accumulation of S100B causes myoblast transition into brown adipocytes. S100B activates an NF-κB/Ying Yang 1 axis that negatively regulates the promyogenic and anti-adipogenic miR-133 with resultant accumulation of the brown adipogenic transcription regulator, PRDM-16. S100B also upregulates BMP-7 via NF-κB/Ying Yang 1 with resultant BMP-7 autocrine activity. Interestingly, myoblasts from sarcopenic humans show features of brown adipocytes. We also show that S100B levels and NF-κB activity are elevated in brown adipocytes obtained by culturing myoblasts in adipocyte differentiation medium and that S100B knockdown or NF-κB inhibition in myoblast-derived brown adipocytes reconverts them into fusion-competent myoblasts. At last, interstitial cells and, unexpectedly, a subpopulation of myofibers in muscles of geriatric but not young mice co-express S100B and the brown adipocyte marker, uncoupling protein-1. These results suggest that S100B is an important intracellular molecular signal regulating Myf5⁺ progenitor cell differentiation into fusion-competent myoblasts or brown adipocytes depending on its levels.

The Pathophysiological Role of Microglia in Dynamic Surveillance, Phagocytosis and Structural Remodeling of the Developing CNS

In vertebrates, during an early wave of hematopoiesis in the yolk sac between embryonic day E7.0 and E9.0, cells of mesodermal leaflet addressed to macrophage lineage enter in developing central nervous system (CNS) and originate the developing native microglial cells. Depending on the species, microglial cells represent 5–20% of glial cells resident in adult brain. Here, we briefly discuss some canonical functions of the microglia, i.e., cytokine secretion and functional transition from M1 to M2 phenotype. In addition, we review studies on the non-canonical functions of microglia such as regulation of phagocytosis, synaptic pruning, and sculpting postnatal neural circuits. In this latter context the contribution of microglia to some neurodevelopmental disorders is now well established. Nasu-Hakola (NHD) disease is considered a primary microgliopathy with alterations of the DNAX activation protein 12 (DAP12)-Triggering receptor expressed on myeloid cells 2 (TREM-2) signaling and removal of macromolecules and apoptotic cells followed by secondary microglia activation. In Rett syndrome Mecp2^-/- microglia shows a substantial impairment of phagocytic ability, although the role of microglia is not yet clear. In a mouse model of Tourette syndrome (TS), microglia abnormalities have also been described, and deficient microglia-mediated neuroprotection is obvious. Here we review the role of microglial cells in neurodevelopmental disorders without inflammation and on the complex role of microglia in developing CNS.

The Proteasome Inhibitor Bortezomib Controls Indoleamine 2,3-Dioxygenase 1 Breakdown and Restores Immune Regulation in Autoimmune Diabetes

Bortezomib (BTZ) is a first-in-class proteasome inhibitor approved for the therapy of multiple myeloma that also displays unique regulatory activities on immune cells. The enzyme indoleamine 2,3-dioxygenase 1 (IDO1) is a tryptophan metabolizing enzyme exerting potent immunoregulatory effects when expressed in dendritic cells (DCs), the most potent antigen-presenting cells capable of promoting either immunity or tolerance. We previously demonstrated that, in inflammatory conditions, IDO1 is subjected to proteasomal degradation in DCs, turning these cells from immunoregulatory to immunostimulatory. In non-obese diabetic (NOD) mice, an experimental model of autoimmune diabetes, we also identified an IDO1 defect such that the DCs do not develop tolerance toward pancreatic islet autoantigens. We found that BTZ rescues IDO1 protein expression in vitro in a particular subset of DCs, i.e., plasmacytoid DCs (pDCs) from NOD mice. When administered in vivo to prediabetic mice, the drug prevented diabetes onset through IDO1- and pDC-dependent mechanisms. Although the drug showed no therapeutic activity when administered alone to overtly diabetic mice, its combination with otherwise suboptimal dosages of autoimmune-preventive anti-CD3 antibody resulted in disease reversal in 70% diabetic mice, a therapeutic effect similar to that afforded by full-dosage anti-CD3. Thus, our data indicate a potential for BTZ in the immunotherapy of autoimmune diabetes and further underline the importance of IDO1-mediated immune regulation in such disease.

Empirical Redundancy of Burnout and Depression: Evidence from Time-standardized Measures

Introduction

Burnout and depression are ordinarily assessed within different time frames. Burnout is most frequently assessed on an annual or a monthly basis whereas depression is generally assessed over a one- or two-week period. This state of affairs may have partly obscured the burnout-depression relationship in past research and contributed to an underestimation of burnout-depression overlap.

Objectives

We investigated burnout-depression overlap using time-standardized measures of the two constructs. We additionally examined whether burnout and depression were differently associated with work-related effort and reward, occupational social support, and intention to quit the job.

Methods

We enrolled 257 Swiss schoolteachers (76% female; mean age: 45). Burnout was assessed with the Shirom-Melamed Burnout Measure and depression with a dedicated module of the Patient Health Questionnaire. Work-related effort and reward were measured with a short version of the Effort-Reward Imbalance Scale and occupational social support with a subscale of the Job Content Questionnaire. Intention to quit the job was assessed with 3 generic items (e.g., “I plan on leaving my job within the next year”).

Results

We observed a raw correlation of .82 and a disattenuated correlation of .91 between burnout and depression. Burnout's dimensions (physical fatigue; cognitive weariness; emotional exhaustion) did not correlate more strongly with each other (mean r = .63) than with depression (mean r = .69). Burnout and depression showed similar associations with the job-related factors under scrutiny.

Conclusions

Burnout and depression may be empirically-redundant constructs. Measurement artifacts probably contributed to an underestimation of burnout-depression overlap in many studies.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

A Person-centered Approach to Burnout-depression Overlap

Introduction

Burnout has widely infiltrated the popular culture and has been extensively studied in both psychiatry and psychology. However, there are currently no consensual or binding diagnostic criteria for burnout. A major obstacle to the elevation of burnout to the status of nosological category is the overlap of burnout with depression.

Objectives

We examined whether burnout and depressive symptoms can be distinguished from each other using a person-centered approach.

Methods

A total of 1759 French schoolteachers took part in the present study (77% female; mean age: 41; mean length of employment: 15). Burnout symptoms were assessed with the Shirom-Melamed Burnout Measure (14 items) and depressive symptoms with a dedicated module of the Patient Health Questionnaire (9 items). Data were primarily processed using two-step cluster analysis. Correlation analysis and analysis of variance (ANOVA) were additionally carried out.

Results

Considered as continuous variables, burnout and depression were found to be closely intertwined (r = 0.81; disattenuated correlation: 0.91). Our cluster analysis revealed four different participant profiles, identifiable as “minimal burnout-depression” (n = 542; 31%), “low burnout-depression” (n = 566; 32%), “medium burnout-depression” (n = 412; 23%), and “high burnout-depression” (n = 239; 14%). Burnout and depression played equivalently important roles in cluster construction. Our ANOVA confirmed that the four clusters differed from each other in terms of burnout and depressive symptoms.

Conclusions

Our findings are consistent with the view that the burnout syndrome is depressive in nature. A diagnostic category dedicated to burnout may therefore not be needed.

Is it Time to Characterize Burnout as a Depressive Syndrome? A Review of Recent Research

Introduction

More than 40 years after the introduction of the construct in the literature, the status of “burnout” remains unclear. Whether burnout is anything other than a depressive syndrome has been increasingly discussed in recent years.

Objectives

We examined the extent to which burnout can be considered distinct from depression.

Methods

We reviewed the literature dedicated to burnout-depression overlap over the last decade.

Results

Recent research suggests that burnout and depression overlap in terms of (a) etiology, with (chronic) unresolvable stress a common, key causal factor, (b) clinical picture and course, with burnout and depressive manifestations inextricably linked such that they increase or decrease together over time, (c) cognitive biases, with burnout and depressive symptoms similarly predicting increased attention to negative stimuli and decreased attention to positive stimuli, (d) dispositional correlates (e.g, neuroticism, rumination, pessimism), and (e) allostatic load—an index of the biological cost of adaptation to life adversity. Hypocortisolism has been linked to both burnout and depression with atypical features—a highly prevalent form of depression. The often-invoked argument that burnout is singularized by its job-related character is actually invalid given that (a) depression can also be job-related and (b) the “job-relatedness” of a syndrome is not nosologically discriminant in itself.

Conclusions

Robust evidence that burnout overlaps with depression has accumulated in recent years. The burnout construct is unlikely to capture a distinct pathological phenomenon. We propose that burnout be characterized as a depressive syndrome for the sake of conceptual parsimony, theoretical clarity, and effective public health policies.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

A Relay Pathway between Arginine and Tryptophan Metabolism Confers Immunosuppressive Properties on Dendritic Cells

Arginase 1 (Arg1) and indoleamine 2,3-dioxygenase 1 (IDO1) are immunoregulatory enzymes catalyzing the degradation of l-arginine and l-tryptophan, respectively, resulting in local amino acid deprivation. In addition, unlike Arg1, IDO1 is also endowed with non-enzymatic signaling activity in dendritic cells (DCs). Despite considerable knowledge of their individual biology, no integrated functions of Arg1 and IDO1 have been reported yet. We found that IDO1 phosphorylation and consequent activation of IDO1 signaling in DCs was strictly dependent on prior expression of Arg1 and Arg1-dependent production of polyamines. Polyamines, either produced by DCs or released by bystander Arg1⁺ myeloid-derived suppressor cells, conditioned DCs toward an IDO1-dependent, immunosuppressive phenotype via activation of the Src kinase, which has IDO1-phosphorylating activity. Thus our data indicate that Arg1 and IDO1 are linked by an entwined pathway in immunometabolism and that their joint modulation could represent an important target for effective immunotherapy in several disease settings.

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Dendritic cells (DCs) can co-express Arg1 and IDO1 immunosuppressive enzymes

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Arg1 activity is required for IDO1 induction by TGF-β in DCs

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Spermidine, a downstream Arg1 product, but not arginine starvation, induces IDO1 in DCs

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Arg1⁺ myeloid derived suppressor cells (MDSCs) can render DCs immunosuppressive via IDO1

Microglia-glioma cross-talk: a two way approach to new strategies against glioma

Glioblastoma (GBM) is the most malignant and aggressive among primary brain tumors, characterized by very low life expectancy. In vivo, glioma and glioblastoma in particular contain large numbers of immune cells (myeloid cells) such as microglia and tumour-infiltrating macrophages (or glioma associated macrophages). These glioma-infiltrating myeloid cells comprise up to 30% of total tumor mass and have been suggested to play several roles in glioma progression including proliferation, survival, motility and immunosuppression. Although tumor microglia and macrophages can acquire proinflammatory (M1) phenotype being capable of releasing proinflammatory cytokines, phagocytosing and presenting antigens, their effector immune function in gliomas appears to be suppressed by the acquisition of an anti-inflammatory (M2) phenotype. In the present work we review the microglia-glioma interactions to highlight the close relationship between the two cell types and the factors that can influence their properties (chemokines, cytokines, S100B protein). A future therapeutic possibility might be to simultaneously targeting, for example with nanomedicine, glioma cells and microglia to push the microglia towards an antitumor phenotype (M1) and/or prevent glioma cells from "conditioning" by microglia.

Postnatal Deletion of Podoplanin in Lymphatic Endothelium Results in Blood Filling of the Lymphatic System and Impairs Dendritic Cell Migration to Lymph Nodes

OBJECTIVE

The lymphatic vascular system exerts major physiological functions in the transport of interstitial fluid from peripheral tissues back to the blood circulation and in the trafficking of immune cells to lymph nodes. Previous studies in global constitutive knockout mice for the lymphatic transmembrane molecule podoplanin reported perinatal lethality and a complex phenotype with lung abnormalities, cardiac defects, lymphedema, blood-filled lymphatic vessels, and lack of lymph node organization, reflecting the importance of podoplanin expression not only by the lymphatic endothelium but also by a variety of nonendothelial cell types. Therefore, we aimed to dissect the specific role of podoplanin expressed by adult lymphatic vessels.

APPROACH AND RESULTS

We generated an inducible, lymphatic-specific podoplanin knockout mouse model (Pdpn^ΔLEC) and induced gene deletion postnatally. Pdpn^ΔLEC mice were viable, and their lymphatic vessels appeared morphologically normal with unaltered fluid drainage function. Intriguingly, Pdpn^ΔLEC mice had blood-filled lymph nodes and vessels, most frequently in the neck and axillary region, and displayed a blood-filled thoracic duct, suggestive of retrograde filling of blood from the blood circulation into the lymphatic system. Histological and fluorescence-activated cell sorter analyses revealed normal lymph node organization with the presence of erythrocytes within lymph node lymphatic vessels but not surrounding high endothelial venules. Moreover, fluorescein isothiocyanate painting experiments revealed reduced dendritic cell migration to lymph nodes in Pdpn^ΔLEC mice.

CONCLUSIONS

These results reveal an important role of podoplanin expressed by lymphatic vessels in preventing postnatal blood filling of the lymphatic vascular system and in contributing to efficient dendritic cell migration to the lymph nodes.