Tissue-resident macrophages originate from yolk-sac-derived erythro-myeloid progenitors

Most haematopoietic cells renew from adult haematopoietic stem cells (HSCs), however, macrophages in adult tissues can self-maintain independently of HSCs. Progenitors with macrophage potential in vitro have been described in the yolk sac before emergence of HSCs, and fetal macrophages can develop independently of Myb, a transcription factor required for HSC, and can persist in adult tissues. Nevertheless, the origin of adult macrophages and the qualitative and quantitative contributions of HSC and putative non-HSC-derived progenitors are still unclear. Here we show in mice that the vast majority of adult tissue-resident macrophages in liver (Kupffer cells), brain (microglia), epidermis (Langerhans cells) and lung (alveolar macrophages) originate from a Tie2(+) (also known as Tek) cellular pathway generating Csf1r(+) erythro-myeloid progenitors (EMPs) distinct from HSCs. EMPs develop in the yolk sac at embryonic day (E) 8.5, migrate and colonize the nascent fetal liver before E10.5, and give rise to fetal erythrocytes, macrophages, granulocytes and monocytes until at least E16.5. Subsequently, HSC-derived cells replace erythrocytes, granulocytes and monocytes. Kupffer cells, microglia and Langerhans cells are only marginally replaced in one-year-old mice, whereas alveolar macrophages may be progressively replaced in ageing mice. Our fate-mapping experiments identify, in the fetal liver, a sequence of yolk sac EMP-derived and HSC-derived haematopoiesis, and identify yolk sac EMPs as a common origin for tissue macrophages.

Environment drives selection and function of enhancers controlling tissue-specific macrophage identities

Macrophages reside in essentially all tissues of the body and play key roles in innate and adaptive immune responses. Distinct populations of tissue macrophages also acquire context-specific functions that are important for normal tissue homeostasis. To investigate mechanisms responsible for tissue-specific functions, we analyzed the transcriptomes and enhancer landscapes of brain microglia and resident macrophages of the peritoneal cavity. In addition, we exploited natural genetic variation as a genome-wide "mutagenesis" strategy to identify DNA recognition motifs for transcription factors that promote common or subset-specific binding of the macrophage lineage-determining factor PU.1. We find that distinct tissue environments drive divergent programs of gene expression by differentially activating a common enhancer repertoire and by inducing the expression of divergent secondary transcription factors that collaborate with PU.1 to establish tissue-specific enhancers. These findings provide insights into molecular mechanisms by which tissue environment influences macrophage phenotypes that are likely to be broadly applicable to other cell types.

Infectious disease. Life-threatening influenza and impaired interferon amplification in human IRF7 deficiency

Severe influenza disease strikes otherwise healthy children and remains unexplained. We report compound heterozygous null mutations in IRF7, which encodes the transcription factor interferon regulatory factor 7, in an otherwise healthy child who suffered life-threatening influenza during primary infection. In response to influenza virus, the patient's leukocytes and plasmacytoid dendritic cells produced very little type I and III interferons (IFNs). Moreover, the patient's dermal fibroblasts and induced pluripotent stem cell (iPSC)-derived pulmonary epithelial cells produced reduced amounts of type I IFN and displayed increased influenza virus replication. These findings suggest that IRF7-dependent amplification of type I and III IFNs is required for protection against primary infection by influenza virus in humans. They also show that severe influenza may result from single-gene inborn errors of immunity.

Immune crosstalk in cancer progression and metastatic spread: a complex conversation

Metastatic disease is responsible for approximately 90% of cancer deaths. For successful dissemination and metastasis, cancer cells must evade detection and destruction by the immune system. This process is enabled by factors secreted by the primary tumour that shape both the intratumoural microenvironment and the systemic immune landscape. Here, we review the evidence of aberrant immune cell crosstalk in metastasis formation and the role that primary tumours play in hijacking these interactions in order to enhance their metastatic potential. Moreover, we highlight the intriguing parallels between the inflammatory pathways underlying inflammatory disorders and cancer progression.

The Heterogeneity of Ly6Chi Monocytes Controls Their Differentiation into iNOS+ Macrophages or Monocyte-Derived Dendritic Cells

Inflammation triggers the differentiation of Ly6C^hi monocytes into microbicidal macrophages or monocyte-derived dendritic cells (moDCs). Yet, it is unclear whether environmental inflammatory cues control the polarization of monocytes toward each of these fates or whether specialized monocyte progenitor subsets exist before inflammation. Here, we have shown that naive monocytes are phenotypically heterogeneous and contain an NR4A1- and Flt3L-independent, CCR2-dependent, Flt3⁺CD11c⁻MHCII⁺PU.1^hi subset. This subset acted as a precursor for FcγRIII⁺PD-L2⁺CD209a⁺, GM-CSF-dependent moDCs but was distal from the DC lineage, as shown by fate-mapping experiments using Zbtb46. By contrast, Flt3⁻CD11c⁻MHCII⁻PU.1^lo monocytes differentiated into FcγRIII⁺PD-L2⁻CD209a⁻iNOS⁺ macrophages upon microbial stimulation. Importantly, Sfpi1 haploinsufficiency genetically distinguished the precursor activities of monocytes toward moDCs or microbicidal macrophages. Indeed, Sfpi1^+/− mice had reduced Flt3⁺CD11c⁻MHCII⁺ monocytes and GM-CSF-dependent FcγRIII⁺PD-L2⁺CD209a⁺ moDCs but generated iNOS⁺ macrophages more efficiently. Therefore, intercellular disparities of PU.1 expression within naive monocytes segregate progenitor activity for inflammatory iNOS⁺ macrophages or moDCs.

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Murine Ly6C^hiCD115⁺ monocytes are heterogeneous

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DC-related genes (Cd209a and MHCII) are expressed in a subset of FcγRIII⁺ monocytes

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GM-CSF-dependent CD209a⁺ moDCs are generated by FcγRIII⁺CD209a⁺MHCII⁺ monocytes

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iNOS⁺ macrophages are generated by FcγRIII⁺CD209a⁻MHCII⁻ monocytes

IL-5-producing CD4+ T cells and eosinophils cooperate to enhance response to immune checkpoint blockade in breast cancer

Immune checkpoint blockade (ICB) has heralded a new era in cancer therapy. Research into the mechanisms underlying response to ICB has predominantly focused on T cells; however, effective immune responses require tightly regulated crosstalk between innate and adaptive immune cells. Here, we combine unbiased analysis of blood and tumors from metastatic breast cancer patients treated with ICB with mechanistic studies in mouse models of breast cancer. We observe an increase in systemic and intratumoral eosinophils in patients and mice responding to ICB treatment. Mechanistically, ICB increased IL-5 production by CD4⁺ T cells, stimulating elevated eosinophil production from the bone marrow, leading to systemic eosinophil expansion. Additional induction of IL-33 by ICB-cisplatin combination or recombinant IL-33 promotes intratumoral eosinophil infiltration and eosinophil-dependent CD8⁺ T cell activation to enhance ICB response. This work demonstrates the critical role of eosinophils in ICB response and provides proof-of-principle for eosinophil engagement to enhance ICB efficacy.

Detection of DNA hybridization using the TISPR-1 surface plasmon resonance biosensor

Biotinylated oligonucleotide probes were immobilized to the gold sensor surface of the TISPR-1 miniature integrated surface plasmon resonance liquid sensor system for the purpose of detecting specific DNA hybridization. The immobilization of the oligonucleotide capture probes was carried out through streptavidin-biotin binding technology. The sensor detected the immobilization of unlabeled DNA through shifts in index of refraction as the molecules entered and remained selectively bound to the surface in the vicinity of the exponentially decaying surface plasmon resonance wave. The surface immobilization chemistry was proven to be stable for long periods of time, reproducible, and practical for detecting DNA hybridization with the TISPR-1. DNA hybridization was detected as a slow, positive, and small (when compared to protein-protein or antibody-antigen binding experiments) increase in the measured index of refraction under passive hybridization conditions by the TISPR-1 sensor. The DNA hybridization signal was significant (index of refraction change of 0.001) when large fragment PCR-amplified DNA products were hybridized to the oligonucleotide probes (S/N = 6-10). The DNA hybridization techniques were demonstrated using DNA sequences from the HIV genome which encode the Tat and Rev genes.

The transcription factor NR4A1 is essential for the development of a novel macrophage subset in the thymus

Tissue macrophages function to maintain homeostasis and regulate immune responses. While tissue macrophages derive from one of a small number of progenitor programs, the transcriptional requirements for site-specific macrophage subset development are more complex. We have identified a new tissue macrophage subset in the thymus and have discovered that its development is dependent on transcription factor NR4A1. Functionally, we find that NR4A1-dependent macrophages are critically important for clearance of apoptotic thymocytes. These macrophages are largely reduced or absent in mice lacking NR4A1, and Nr4a1-deficient mice have impaired thymocyte engulfment and clearance. Thus, NR4A1 functions as a master transcription factor for the development of this novel thymus-specific macrophage subset.

PD-L1 blockade in combination with carboplatin as immune induction in metastatic lobular breast cancer: the GELATO trial

Invasive lobular breast cancer (ILC) is the second most common histological breast cancer subtype, but ILC-specific trials are lacking. Translational research revealed an immune-related ILC subset, and in mouse ILC models, synergy between immune checkpoint blockade and platinum was observed. In the phase II GELATO trial ( NCT03147040 ), patients with metastatic ILC were treated with weekly carboplatin (area under the curve 1.5 mg ml-1 min-1) as immune induction for 12 weeks and atezolizumab (PD-L1 blockade; triweekly) from the third week until progression. Four of 23 evaluable patients had a partial response (17%), and 2 had stable disease, resulting in a clinical benefit rate of 26%. From these six patients, four had triple-negative ILC (TN-ILC). We observed higher CD8+ T cell infiltration, immune checkpoint expression and exhausted T cells after treatment. With this GELATO trial, we show that ILC-specific clinical trials are feasible and demonstrate promising antitumor activity of atezolizumab with carboplatin, particularly for TN-ILC, and provide insights for the design of highly needed ILC-specific trials.

Melanoma today does not require radical surgery

From this study we conclude that melanoma has a more favorable outcome today than 20 years ago, 2 cm margins around the tumor achieve acceptable survival and local recurrence rates, primary closure is preferred when possible, elective regional node dissection is of questionable value, and further trials are warranted to determine optimal therapy for intermediate thickness melanoma.

Neoadjuvant immune checkpoint blockade triggers persistent and systemic Treg activation which blunts therapeutic efficacy against metastatic spread of breast tumors

The clinical successes of immune checkpoint blockade (ICB) in advanced cancer patients have recently spurred the clinical implementation of ICB in the neoadjuvant and perioperative setting. However, how neoadjuvant ICB therapy affects the systemic immune landscape and metastatic spread remains to be established. Tumors promote both local and systemic expansion of regulatory T cells (T_regs), which are key orchestrators of tumor-induced immunosuppression, contributing to immune evasion, tumor progression and metastasis. T_regs express inhibitory immune checkpoint molecules and thus may be unintended targets for ICB therapy counteracting its efficacy. Using ICB-refractory models of spontaneous primary and metastatic breast cancer that recapitulate the poor ICB response of breast cancer patients, we observed that combined anti-PD-1 and anti-CTLA-4 therapy inadvertently promotes proliferation and activation of T_regs in the tumor, tumor-draining lymph node and circulation. Also in breast cancer patients, T_reg levels were elevated upon ICB. Depletion of T_regs during neoadjuvant ICB in tumor-bearing mice not only reshaped the intratumoral immune landscape into a state favorable for ICB response but also induced profound and persistent alterations in systemic immunity, characterized by elevated CD8+ T cells and NK cells and durable T cell activation that was maintained after treatment cessation. While depletion of T_regs in combination with neoadjuvant ICB did not inhibit primary tumor growth, it prolonged metastasis-related survival driven predominantly by CD8+ T cells. This study demonstrates that neoadjuvant ICB therapy of breast cancer can be empowered by simultaneous targeting of T_regs, extending metastasis-related survival, independent of a primary tumor response.

The Shwartzman phenomenon in equine species

The occurrence of the Local Shwartzman Reaction (LSR) in equine species has not previously been reported. The molecular mechanism appears identical to that reported for the rabbit and other species. The immunopathologic and histopathologic similarities of the experimentally induced LSR in horses and ponies to that of the hoof-laminae (an extension of the skin) lesion in naturally-occurring and/or carbohydrate induced laminitis may offer insight into the pathogenesis of this complex disease.

Fabrication and evaluation of a near-infrared hyperspectral imaging system

This paper describes modifications to a hyperspectral imaging microscope that extend its capabilities into the near-infrared (950-1300 nm). The major changes include installing a grating, charge-coupled device camera, and lenses and filters appropriate for infrared wavelengths. Calibration of the system and validation with lead sulfide quantum dots of known emission wavelength is reported. Cells from the breast carcinoma cell line SkBr3 were scanned with lead sulfide quantum dots that emit at 1100 nm as the background and an image which contains the integrated spectral data is presented. We also demonstrate that this instrument is capable of detecting the photoluminescence spectra of single-walled carbon nanotubes dispersed in aqueous solution.

Triple-negative breast cancer modifies the systemic immune landscape and alters neutrophil functionality

Cancer disrupts intratumoral innate-adaptive immune crosstalk, but how the systemic immune landscape evolves during breast cancer progression remains unclear. We profiled circulating immune cells in stage I-III and stage IV triple-negative breast cancer (TNBC) patients and healthy donors (HDs). Metastatic TNBC (mTNBC) patients had reduced T cells, dendritic cells, and differentiated B cells compared to non-metastatic TNBC patients and HDs, partly linked to prior chemotherapy. Vδ1 γδ T cells from mTNBC patients produced more IL17 than those from HDs. Chemotherapy-naïve mTNBC patients showed increased classical monocytes and neutrophils. Transcriptional, proteomic, and functional analyses revealed that neutrophils in mTNBC exhibited enhanced migratory capacity, elevated granule proteins, and higher ROS production. Some immune changes, such as reduced non-switched B cells and heightened neutrophil migration, were evident in earlier TNBC stages. This study comprehensively maps systemic immunity in TNBC, guiding future research on patient stratification and immunomodulation strategies.

Multiplexed Tumor Marker Profiling at Single-Cell Resolution: Quantifying Breast Cancer Molecular Signatures

Excluding skin cancers, about 1.5 million new cases of cancer and about 450,000 cancer related deaths occur each year in the United States. The validation and molecular profiling of tumor markers are contributing to new paradigms in cancer research. In this presentation, we will discuss the information that can be obtained by using an Intelligent Single-Cell Optical Profiling Engine (I-SCOPE), consisting of hyperspectral imaging, multiplexed biomarker kits, and bioinformatics tools, to markedly expand the molecular profiling of tumor markers on individual carcinoma cells.Using biomarker antibodies conjugated to particular fluorochromes, we developed a multiplex of 10 different fluorochrome conjugates, one for each different tumor marker plus a nuclear dye. Staining and scanning using the I-SCOPE system showed that it can presently distinguish 10 different fluorochromes in a single pass, resulting in the identification of spatial location and relative intensity of each biomarker being interrogated. By using this system, we analyzed thousands of tumor cells from touch preparations of tumor tissue, circulating tumor cells (CTCs) in pleural fluid and blood, and disseminated tumor cells (DTCs) from bone marrow with 2 multiplex kits for a total of 17 different tumor markers. We have utilized clinically-accepted markers such as estrogen receptor (ER), progesterone receptor (PR), and HER2 in addition to biomarkers undergoing investigation such as B-cell lymphoma 2 (Bcl-2) and urokinase-type plasminogen receptor (uPAR). Furthermore, with the ability to simultaneously image 10 markers, each panel can also contain desired positive and negative controls such as CD45 (positive for white blood cells, negative for CTCs) and cytokeratin (positive for epithelial cells).The results of immunophenotyping of individual tumor cells with 17 different tumor markers indicated that the average expression of each tumor marker in 25 tumor cells was a reproducible representation of the tumor. However, comparison of individual CTCs' expression levels revealed remarkable heterogeneity in primary breast cancer cases.We conclude that hyperspectral microscope imaging together with individual tumor cell analysis represents a major step forward in developing a far more detailed and precise molecular signature of a patient's cancer. Further studies might demonstrate how it can facilitate treatment tailored to the individual patient's tumor, an important objective as new oncology drugs with specific molecular targets become more prevalent.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 6002.

School Safety Concerns and Solutions: A Qualitative Analysis of U.S. School Psychologists' Perspectives

In the present study, we analyzed qualitative survey data from 538 school psychologists across schools in the United States regarding their perceptions of school safety issues and potential strategies to address school safety. There are only a few studies exploring the experiences and perspectives of school psychologists that have been based on large-scale qualitative data. Using inductive coding, three themes for safety concerns emerged: (a) aggressive behaviors from students, (b) mental and behavioral needs, and (c) limited staffing. Three themes also emerged for potential solutions: (a) professional development/training, (b) school-family-community relationships, and (c) threat assessments. These findings from school psychologists have implications for addressing structural issues to prevent school violence in research and practice. Policy recommendations to inform resource allocation and improve school safety are discussed.