Cells Of Myeloid Origin Research Articles

Current ideas on the pathogenesis of osteoporosis in chronic lymphatic leukemia (literature review)

Background. Chronic lymphocytic leukemia (CLL) is the second most common hematological malignancy without a trend towards a decrease in its incidence. 66 % of patients with CLL experience bone fractures as a result of osteoporosis in all age groups, and the detection frequency is no more than 15 %. Insufficient understanding of the osteoporosis pathogenesis in CLL leads to problems in diagnosis, prevention and therapy.The aim of the study. To analyze modern data on the features of the osteoporosis pathogenesis in chronic lymphocytic leukemia.Results and discussion. Osteoporosis is formed when osteoresorption prevails over osteosynthesis due to intercellular interactions of bone tissue and the immune system, dysregulation of intracellular signaling pathways RANKL/RANK/OPG, Wnt, FoxO, RUNX2, initiated by cytokines, growth factors, prostaglandins, and hormones. The degree of osteoresorption in CLL is associated with the severity of the clinical course, chemotherapy and hormonal deprivation. The osteoporosis pathogenesis in CLL is considered as part of a complex set of events, including, firstly, the interaction between leukemic cells (overexpression of PTHrP, RANKL) and bone cells (synthesis of growth factors), which forms a vicious circle of osteoresorption and tumor growth. Secondly, pro-inflammatory markers in CLL (tumor necrosis factor α, interleukin (IL) 1β, IL-6, IL-8, IL-11, granulocyte-macrophage colony-stimulating factor, macrophage colony-stimulating factor, transforming growth factor β, prostaglandin E2) limit osteoblast-induced osteosynthesis and stimulate the expansion of osteoclasts from monocytic suppressor cells of myeloid origin with or without the participation of the RANKL/RANK system. Thirdly, oxidative stress in CLL and impaired efficiency of antioxidant protection with the participation of fibroblast growth factor 23, transcription factor Nrf-2 with activation of JNK, ERK1/2, NF-κB, and also an increase in the RANKL/OPG ratio lead to inhibition of osteoblastogenesis.Conclusion. Analyzing and systematizing data on the osteoporosis pathogenesis in CLL are instrumental for the development of diagnostic criteria for osteoporosis in chronic lymphocytic leukemia that are much-needed in clinical practice and for the improvement of therapeutic tactics.

The expression of signal regulatory protein alpha (SIRPα) in periodontal cells and tissue.

Signal regulatory protein alpha (SIRPα) is mainly expressed by cells of myeloid origin. This membrane glycoprotein is shown to be involved in regulation of different inflammatory conditions, such as colitis and arthritis. However, SIRPα has not been investigated in relationship to periodontitis, an inflammatory condition affecting the tooth supporting tissues. We aim to investigate if resident cells in the periodontium express SIRPα and whether a possible expression is affected by inflammatory conditions. Primary human keratinocytes, fibroblasts, periodontal ligament cells, and osteoblasts were cultured with or without the pro-inflammatory cytokines tumor necrosis factor alpha (TNF-α) or interleukin-1-beta (IL-1β). All different periodontal cell types showed a basal mRNA expression of SIRPα. Pro-inflammatory cytokines induced a 2-3-fold significant increase in SIRPα expression in both cultured human gingival fibroblasts and osteoblasts but neither in keratinocytes nor in periodontal ligament cells. Tissue sections from human gingival tissue biopsies were histochemically stained for SIRPα. Epithelial keratinocytes and gingival fibroblasts stained positive in sections from periodontally healthy as well as in sections from periodontitis. In periodontitis sections, infiltrating leukocytes stained positive for SIRPα. We highlight our finding that oral keratinocytes, gingival fibroblasts, and periodontal ligament cells do express SIRPα, as this has not been presented before. The fact that inflammatory stimulation of gingival fibroblasts increased the expression of SIRPα, while an increased expression by gingival fibroblasts in periodontitis tissue in situ could not be detected, is indeed contradictory.

Keratinocyte and myeloid MCPIP1 have distinct roles in maintaining skin homeostasis

The skin is a complex organ, and the intricate network between keratinocytes and immune cells is critical for ensuring skin function. Monocyte chemotactic protein-1-induced protein 1 (MCPIP1) is a ribonuclease that functions as a key negative modulator of inflammation. We previously reported that conditional deletion of MCPIP1 in keratinocytes (Mcpip1EKO) impairs skin integrity in adult mice. A similar phenotype was observed following the depletion of MCPIP1 in the myeloid compartment (Mcpip1MKO).The aim of this study was to develop a keratinocyte and myeloid double-MCPIP1 knockout mouse model to clarify the specific roles of myeloid and epidermal MCPIP1 in skin biology.Histological analyses indicated that the skin morphology changed after depletion of MCPIP1 in cells of myeloid origin as well as in keratinocytes. The thicknesses of the epidermal and subcutaneous fat layers increased in the mice with a loss of epidermal MCPIP1, whereas the loss of myeloid MCPIP1 had the opposite effect. In addition, both types of mice showed opposite responses to stimulation with 12-O-tetradecanoylphorbol-13-acetate. Transcriptomic profiling of whole-skin lysates revealed some common target transcripts in all the knockout mice. Further analyses revealed that distinct pathways are modulated following the loss of epidermal or myeloid MCPIP1. The skin morphology and inflammatory phenotype of keratinocyte and myeloid double-MCPIP1 knockout mice resembled those of mice with only keratinocyte-specific knockout of MCPIP1.Overall, myeloid and epidermal MCPIP1 play important but distinct roles in the modulation of skin-related processes.

Leukocyte immunoglobulin-like receptor (LILRB2)-targeted JTX-8064 plus the anti-PD1 inhibitor JTX-4014 (pimivalimab) in immune-checkpoint inhibitor (ICl) pretreated patients (pts) with advanced or metastatic renal cell cancer (mRCC): Results from the multi-stage phase 1-2 INNATE trial.

4531 Background: Disease progression following treatment of mRCC pts with ICl-based therapy (tx) is nearly universal, warranting evaluation of novel immunotherapeutic approaches. LILRB2 is an immune checkpoint molecule expressed primarily in cells of myeloid origin (e.g., monocytes/macrophages). Inhibition of LILRB2 reprograms macrophages from an immunosuppressive (M2) to an immunostimulatory (M1) phenotype. JTX-8064 is a humanized monoclonal antibody that binds to LILRB2, blocking its interaction with MHC1 molecules. Preclinical studies suggest that JTX-8064 can overcome anti-PD(L)1 resistance mechanisms. Here we report the results of an expansion cohort of previously-treated mRCC pts in INNATE, a multi-stage phase 1-2 trial of JTX-8064 in combination with anti-PD1 agents in solid tumors. Methods: Pts with pathologically-confirmed clear cell mRCC progressing on or after anti-PD(L)1 tx in the most recent prior line, acceptable end-organ function, and ECOG PS 0-1 were treated with JTX-8064 700 mg and JTX-4014 500 mg IV q3 weeks. Primary endpoint was overall response rate (ORR); secondary endpoints were safety, disease control rate (DCR), progression-free survival (PFS), & overall survival (OS). A Simon 2-stage design (n=10+19) was employed where ORR >= 20% was deemed to be of further interest versus null hypothesis of ORR <= 5%, with alpha=0.05. Results: 31 pts were enrolled, with median age of 64 years (range 38-85); 84% males; 16% Hispanic; 93% White; 45% PS=0; 71% one prior tx line. Of 28 pts evaluable for response, 1 CR, 1 PR, 14 SD (6 SD>= 6 months), and 11 PD were seen for an ORR of 7% & DCR of 54%.Median PFS was 4 months (95%CI: 2, 6.8); 12-month OS was 75% (95%CI: 55,88). Tx-related adverse events (AE) of all grades were reported in 11 pts (45%), most commonly fatigue (16%) & diarrhea (10%). Only 4 protocol-related G3-4 AEs were reported: thrombocytopenia (G4); diplopia, diarrhea, & bradycardia (all G3). Three on-study deaths (hypotension; cardiorespiratory arrest; & unknown) were deemed unrelated to protocol tx. Conclusions: While ORR did not meet the protocol-defined efficacy target, evidence of anti tumor activity was seen in ICI pre-treated mRCC pts with combination JTC-8064 + JTX-4014. Treatment was reasonably well-tolerated. Identification & evaluation of clinical and molecular phenotypes most likely to benefit from LILRB2-targeted therapies are warranted. Clinical trial information: NCT04669899 .

Abstract LB332: Spatial transcriptomic and proteomic analysis of the treatment resistant slow cycling micro environment in GBM

Abstract Within the Glioblastoma (GBM) microenvironment, there are micro-niches originating from independent lineages of cancer stem cells with distinct metabolic requirements that are characterized by Fast cycling cells (FCCs) and Slow cycling cells (SCC). The FCCs employ aerobic glycolysis for energy, while the treatment-resistant SCCs primarily rely on lipid metabolism. Our study allows for the molecular and spatial decoding of the heterogeneity within the GBM microenvironment, with a specific focus on decoding the dichotomy of the immune infiltrates and studying the interactions between the SCCs and the immune compartment in human GBM patients. Our research reveals a new paradigm of interaction within the tumor microenvironment (TME) of glioblastoma (GBM) patients, in which SCCs are instrumental in altering the tumor milieu to favor immune suppression. These SCCs actively recruit and harness sub-population of immune cells of myeloid origin that promote tumor growth and simultaneously provide metabolic aid to these treatment-resistant cells. Our research maps out the intricate metabolic dialogues within GBM and evaluates the potential therapeutic effect of disrupting this interaction to open up new treatment avenues. The findings based on our spatial transcriptomic and proteomic study on brain biopsies from human patients provide a deeper understanding of the critical links among the tumor's local environment, cellular metabolism, anti-tumor immunity, and potential treatment vulnerabilities. In summary, our investigation offers novel insights into how metabolic exchanges contribute to the evolution of GBM leading to the development of drug and immune resistant GBM. Our data is suggestive that therapies aimed at these metabolic interactions, especially those between SCCs and metabolically supporting immunosuppressive myeloid originating immune cells, hold potential as effective therapeutic strategy for GBM. Citation Format: Avirup Chakraborty, Diana Feier, Aryeh Silver, Changlin Yang, Miruna Anica, Avinash Pittu, Olusegun Sobanjo, Ethan Hodge, Mia Engelbart, Christina Von Roemeling, Maryam Rahman, Matthew Sarkisian, Jianping Huang, Jeffrey Harrison, Duane Mitchell, Loic Deleyrolle. Spatial transcriptomic and proteomic analysis of the treatment resistant slow cycling micro environment in GBM [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB332.

Role of Monocyte/Macrophages in the Pathogenesis of NeuroHIV.

Monocyte/macrophages are cells of myeloid origin which play critical roles in innate and adaptive immune responses as well as surveillance and tissue repair. Only recently, the role of monocytes/macrophages in acute and chronic HIV Infection has become accepted. Here, we will focus on monocyte/macrophages on transmigration events and their role as viral reservoirs.

TL-895, a Highly Selective, Covalent Inhibitor of Bruton's Tyrosine Kinase (BTK), Sensitizes Myeloproliferative Neoplasm (MPN)-Blast Phase Stem Cells to Navtemadlin By Targeting Intrinsic Dysregulated MDM2/p53 and NF-Κb Pathways and Disrupting the Protective Tumor Microenvironment (TME)

We recently reported that navtemadlin (nvtm), a potent, orally available, selective inhibitor of MDM2 (MDM2i), can deplete/eliminate TP53WT MPN-blast phase (BP) stem cells (SC) in an MPN-BP patient (pt)-derived xenograft (PDX) model (Wang EHA 2023). Single agent nvtm has demonstrated significant clinical activity in pts with advanced myelofibrosis (MF) (Vachhani EHA 2023, Verstovsek Future Oncology 2022). We hypothesized that effects of nvtm on MPN-BP, which is characterized by multiple SC subclones, could be enhanced by combination with agents that target additional MPN-BP SC vulnerabilities, such as hyperactivation of p65 subunit of NF-κB (Fisher Leukemia 2017; our unpublished data) and dependence on TME support. BTK and bone marrow (BM) kinase X-linked (BMX) are key Tec family members expressed in cells of myeloid origin. Here, we show BTK is constitutively activated in MPN-BP SC subpopulations relative to normal donor (ND) hematopoietic SCs (HSC) and progenitors [phospho (p)-BTK Y233 mean fluorescence intensity fold change (FC)]: CD34 +CD38 - cells: 1.34±0.18, HSC/multipotent progenitor (MPP): 1.50±0.23, multi-lymphoid progenitor (MLP): 1.59±0.59, megakaryocyte-erythroid progenitor (MEP): 1.56±0.49; p <0.05]. TL-895 is a highly selective, potent, orally available, second-generation covalent inhibitor of BTK and BMX, currently under clinical evaluation for treatment of pts with CLL (NCT02825836) and MF (NCT04655118). We used multi-modal single-cell analysis to study mechanistic effects of combination TL-895 + nvtm on dysregulated intracellular signaling pathways in primary MPN-BP SC, and investigated the combination in a PDX model of MPN-BP. In vitro treatment with TL-895 alone (100 nM-5 µM) did not affect growth of ND CD34 + cells [FC (TL-895 vs. vehicle, veh): 2.5 µM: 1.27±0.11, 5 µM: 0.97±0.14, n=3)] but modestly decreased growth of primary TP53WT MPN-BP CD34 + cells, in a dose dependent fashion [FC (TL-895 vs. veh): 2.5 µM: 0.88±0.11, 5 µM: 0.62±0.12, n=4. p<0.05). Addition of TL-895 (5 µM) to nvtm (400 nM) resulted in much greater reductions in MPN-BP CD34 + and CD34 +CD38 - cell numbers, along with increased apoptosis (n=6, p<0.05, TL-895 + nvtm vs. veh, TL-895, or nvtm alone). By contrast, at these doses, combination TL-895 + nvtm did not affect ND HSC subpopulations (n=3). We previously demonstrated that, multiple MPN-BP SC subclones contribute to the development of MPN-BP irrespective of clone size, and minor subclones may be responsible for clonal evolution and disease progression in most cases (Wang JCI insight 2022). Strikingly, single cell mutational profiling and epitope analysis of primary MPN-BP CD34 + cells treated with TL-895 + nvtm showed depletion of all 8 distinct MPN-BP SC subclones with differing variant allele frequencies, each containing 2-3 oncogenic mutations in WT1, ETV6 and/or KRAS. Combination TL-895 + nvtm treatment depleted 7 of 8 subclones to a greater degree than either agent alone (Fig. 1). Bulk RNA-seq and gene set enrichment analysis showed that combination TL-895 + nvtm synergistically upregulated p53 pathway gene transcription ( CDKN1 HDM2, DDB2, BTG2, GADD45A, FAS, FUCA1, S100A10, ATF3) in primary MPN-BP CD34 + cells. Mass cytometry analysis and intracellular flow cytometry of MPN-BP CD34 + cells treated with combination TL-895 + nvtm further revealed significant (p<0.05) upregulation of p53 and BAX proteins and decreases in the anti-apoptotic factors BCL-xL and activated NF-κB (p-p65), as well as significant reductions in DNA synthesis and protein markers associated with glycolysis (p-AMPK, MCT1). Downregulation of NF-κB activation might result from decreases in the upstream modulators p-S6 and p-4EBP1 (p<0.05, TL-895 + nvtm vs. veh). Treatment in vivo withTL-895 promoted dose-dependent egress of hCD45 +CD34 + cells from BM into the spleen and peripheral blood (PB) of MPN-BP PDX mice (Fig. 2). Furthermore, a limited course of combination TL-895 + nvtm treatment for 3 cycles led to clearance of hCD45 +CD34 + cells from the BM, spleen and PB of MPN-BP PDX mice (Fig. 2); neither treatment had this effect when administered alone. Our results indicate that BTKi therapy might increase susceptibility of MPN-BP SC to MDM2i therapy, by upregulating p53 activity and dampening NF-κB signaling, and also by disrupting protective TME interactions that sustain MPN-BP SC. This novel combination merits further clinical investigation in advanced phase MPN.

Effect of pregnancy-specific β1-glycoprotein on the expression of arginase-1 and indolamine-2,3-dioxygenase by myeloid-derived suppressor cells

Myeloid-derived suppressor cells (MDSC) - a population of immature cells of myeloid origin with inhibitory functions, mainly related to T lymphocytes. Normally, MDSC account for less than 1% of leukocytes in peripheral blood. The number of these cells increases during healthy pregnancy. However, MDSC have been shown to play a critical role in the maintenance of tumor growth and in autoimmune diseases.
 Because MDSC are now considered important regulators of immunity, finding ways to manipulate their functions is important for the development of therapies for malignant and autoimmune diseases, as well as for pregnancy pathologies and post-transplant complications. The immunosuppressive mechanisms of these cells are mediated by their expression of the surface molecules CD73, ADAM17, PD -L1, the enzymes arginase 1 (Arg 1), inducible nitric oxide synthase (iNOS), and indoleamine 2,3-dioxygenase (IDO), reactive oxygen species, and the production of the anti-inflammatory cytokines IL -10 and TGF-1.
 Pregnancy-specific 1-glycoprotein (PSG) is a pregnancy glycoprotein that has immunomodulatory effects on natural (dendritic cells and macrophages) and adaptive (T cells) immunity cells. At the same time, the effect of PSG on MDSC has not been investigated so far. Since this glycoprotein has promising pharmacological applications, it is necessary to study not only the native variant of PSG but also its recombinant form.
 Since the main function of MDSC is immunosuppression, the aim of our work was to evaluate one of its mechanisms, namely the intracellular expression of amino acid degradation enzymes Arg1 and IDO under the influence of native and recombinant PSG in vitro.
 MDSC differentiation was performed from CD11b+ cells isolated from peripheral blood of healthy volunteers. Cells were cultured for 7 days with stepwise addition of GM-CSF, IL -1, and LPS. Native (n) (1, 10, and 100 g/mL) and recombinant (r) (1 and 10 g/mL) PSG was added to the cultures three days before the end of incubation. The percentage of MDSCs (Lin- HLA-DR -CD11b+CD33+) intracellularly expressing Arg1 and IDO was determined by flow cytometry.
 It was found that nPSG and rPSG did not alter the amount of Arg1-expressing MDSCs at all concentrations examined. However, at a concentration of 10 g/mL, both types of proteins caused a statistically significant increase in the percentage of cells expressing IDO.
 We have already established that nPSG and rPSG affect MDSC differentiation by increasing the proportion of these cells belonging to the monocytic subpopulation. However, now we can say that PSG, in addition, enhances the suppressive function of the studied cells.
 The obtained data are novel and open perspectives for targeting myeloid suppressor cells to improve cellular technologies in science and medicine.

Depletion of Mcpip1 in murine myeloid cells results in intestinal dysbiosis followed by allergic inflammation

MCPIP1 (called also Regnase-1) is a negative regulator of inflammation. Knockout of the Zc3h12a gene, encoding Mcpip1 in cells of myeloid origin (Mcpip1MKO), has a pathological effect on many organs. The aim of this study was to comprehensively analyze pathological changes in the skin caused by Mcpip1 deficiency in phagocytes with an emphasis on its molecular mechanism associated with microbiome dysbiosis.Mcpip1MKO mice exhibited spontaneous wound formation on the skin. On a molecular level, the Th2-type immune response was predominantly characterized by an increase in Il5 and Il13 transcript levels, as well as eosinophil and mast cell infiltration. Irritation by DNFB led to a more severe skin contact allergy in Mcpip1MKO mice. Allergic reactions on the skin were strongly influenced by gut dysbiosis and enhanced systemic dissemination of bacteria. This process was followed by activation of the C/EBP pathway in peripheral macrophages, leading to local changes in the cytokine microenvironment that promoted the Th2 response. A reduced bacterial load inhibited allergic inflammation, indicating the role of intestinal dysbiosis in the development of skin diseases. Our results clearly show that MCPIP1 in phagocytes is an essential negative regulator that controls the gut-skin axis.

Strategic self-limiting production of infectious HIV particles by CRISPR in permissive cells

Post-translational glycosylation of the HIV-1 envelope protein involving precursor glycan trimming by mannosyl oligosaccharide glucosidase (MOGS) is critically important for morphogenesis of virions and viral entry. Strategic editing of the MOGS gene in T lymphocytes and myeloid origin cells harboring latent proviral DNA results in the production of non-infectious particles upon treatment of cells with latency reversal agents. Controlled activation of CRISPR-MOGS by rebound HIV-1 mitigates production of infectious particles that exhibit poor ability of the virus to penetrate uninfected cells. Moreover, exclusive activation of CRISPR in cells infected with HIV-1 alleviates concern for broad off-target impact of MOGS gene ablation in uninfected cells. Combination CRISPR treatment of peripheral blood lymphocytes prepared from blood of people with HIV-1 (PWH) tailored for editing the MOGS gene (CRISPR-MOGS) and proviral HIV-1 DNA (CRISPR-HIV) revealed a cooperative impact of CRISPR treatment in inhibiting the production of infectious HIV-1 particles. Our design for genetic inactivation of MOGS by CRISPR exhibits no detectable off-target effects on host cells or any deleterious impact on cell survival and proliferation. Our findings offer the development of a new combined gene editing-based cure strategy for the diminution of HIV-1 spread after cessation of antiretroviral therapy (ART) and its elimination.

Features of the microenvironment of oncourological tumors

The interaction of tumor cells, especially if they are stem or resting, with myeloid and lymphoid components, as well as extracellular matrix producers, leads to the formation of a pathological microenvironment that causes resistance to many systemic treatment options. The aim of the work is to present modern literature and own data concerning the features of the composition and structure of the microenvironment in tumors of the kidney, prostate and bladder. The article presents data on the composition and interaction of various subpopulations of cells in the tumor microenvironment, as well as on the role of stem tumor cells in its formation. Defects of signaling pathways of stem tumor cells are described, as well as the mechanism of interaction between the tumor and the immune system in the process of carcinogenesis. Approaches to the assessment of the type of microenvironment for the purpose of individualization of treatment are analyzed in detail. The authors present their own data on the nature of the distribution of subpopulations of lymphocytes and suppressor cells of myeloid origin in patients with metastatic forms of tumors of the genitourinary tract. The variants of using data on the structure of the microenvironment in order to optimize treatment tactics in cancer patients are indicated.

Clinico-Pathological Features of Chronic Myelocytic Leukemia (CML) in Patients Presenting at A Tertiary Care Center

Introduction: Chronic myelocytic leukemia (CML) is a slow growing disorder marked by excessive proliferation of cells of myeloid origin which do not lose their capacity to differentiate. Because of unavailability and un-affordability of such markers in most of our tertiary care centers, it is important to have a better understanding of clinical and hematological insight of this disease. Objective: To determine the clinical and hematological features of chronic myelocytic leukemia on bone marrow examination and trephine biopsy Material and method: The current study was cross-sectional study carried out at the Department of Hematology, Hayatabad medical complex, Peshawar from 8/4/2021 to 8/10/2021. In this study a total 196 patients were observed. The findings of bone marrow aspirate for morphology and phase of the disease, along with the trephine biopsy for bone marrow fibrosis were noted. All data with the demographic information like name, age, gender, occupation for further analysis were recorded. Results: In the current study, totally 196 patients were included. There were 112(57%) male patients and 84(43%) patients were female in our study. Based on clinical features and hematological features of patients with chronic myelocytic leukemia, 153(78%) patients had splenomegaly, 102(52%) patients had fever, 192(98%) patients had leukocytosis, 94(48%) patients had anemia. Conclusion: Our study concludes that the frequency of clinical and hematological features i.e. splenomegaly was 78%, fever was 52%, leukocytosis was 98%, anemia was 48% in patients presenting with chronic myelocytic leukemia. Keywords: clinical and hematological features, chronic myeloid leukemia.

System-wide identification of myeloid markers of TB disease and HIV-induced reactivation in the macaque model of Mtb infection and Mtb/SIV co-infection.

Mycobacterium tuberculosis (Mtb) has developed specialized mechanisms to parasitize its host cell, the macrophage. These mechanisms allow it to overcome killing by oxidative burst and persist in the wake of an inflammatory response. Mtb infection in the majority of those exposed is controlled in an asymptomatic form referred to as latent tuberculosis infection (LTBI). HIV is a well-known catalyst of reactivation of LTBI to active TB infection (ATB). Through the use of nonhuman primates (NHPs) co-infected with Mtb and Simian Immunodeficiency Virus (Mtb/SIV), we are able to simulate human progression of TB/AIDS comorbidity. The advantage of NHP models is that they recapitulate the breadth of human TB outcomes, including immune control of infection, and loss of this control due to SIV co-infection. Identifying correlates of immune control of infection is important for both vaccine and therapeutics development. Using macaques infected with Mtb or Mtb/SIV and with different clinical outcomes we attempted to identify signatures between those that progress to active infection after SIV challenge (reactivators) and those that control the infection (non-reactivators). We particularly focused on pathways relevant to myeloid origin cells such as macrophages, as these innate immunocytes have an important contribution to the initial control or the lack thereof, following Mtb infection. Using bacterial burden, C-reactive protein (CRP), and other clinical indicators of disease severity as a guide, we were able to establish gene signatures of host disease state and progression. In addition to gene signatures, clustering algorithms were used to differentiate between host disease states and identify relationships between genes. This allowed us to identify clusters of genes which exhibited differential expression profiles between the three groups of macaques: ATB, LTBI and Mtb/SIV. The gene signatures were associated with pathways relevant to apoptosis, ATP production, phagocytosis, cell migration, and Type I interferon (IFN), which are related to macrophage function. Our results suggest novel macrophage functions that may play roles in the control of Mtb infection with and without co-infection with SIV. These results particularly point towards an interplay between Type I IFN signaling and IFN-γ signaling, and the resulting impact on lung macrophages as an important determinant of progression to TB.

New Perspectives on Myeloid-Derived Suppressor Cells and Their Emerging Role in Haematology.

Myeloid-derived suppressor cells (MDSCs) are immature cells of myeloid origin that have gained researchers’ attention, as they constitute promising biomarkers and targets for novel therapeutic strategies (i.e., blockage of development, differentiation, depletion, and deactivation) in several conditions, including neoplastic, autoimmune, infective, and inflammatory diseases, as well as pregnancy, obesity, and graft rejection. They are characterised in humans by the typical immunophenotype of CD11b+CD33+HLA-DR–/low and immune-modulating properties leading to decreased T-cell proliferation, induction of T-regulatory cells (T-regs), hindering of natural killer (NK) cell functionality, and macrophage M2-polarisation. The research in the field is challenging, as there are still difficulties in defining cell-surface markers and gating strategies that uniquely identify the different populations of MDSCs, and the currently available functional assays are highly demanding. There is evidence that MDSCs display altered frequency and/or functionality and could be targeted in immune-mediated and malignant haematologic diseases, although there is a large variability of techniques and results between different laboratories. This review presents the current literature concerning MDSCs in a clinical point of view in an attempt to trigger future investigation by serving as a guide to the clinical haematologist in order to apply them in the context of precision medicine as well as the researcher in the field of experimental haematology.

Human Microglia-like Cells: Differentiation from Induced Pluripotent Stem Cells and In Vitro Live-cell Phagocytosis Assay using Human Synaptosomes.

Microglia are the resident immune cells of myeloid origin that maintain homeostasis in the brain microenvironment and have become a key player in multiple neurological diseases. Studying human microglia in health and disease represents a challenge due to the extremely limited supply of human cells. Induced pluripotent stem cells (iPSCs) derived from human individuals can be used to circumvent this barrier. Here, it is demonstrated how to differentiate human iPSCs into microglia-like cells (iMGs) for in vitro experimentation. These iMGs exhibit the expected and physiological properties of microglia, including microglia-like morphology, expression of proper markers, and active phagocytosis. Additionally, documentation for isolating and labeling synaptosome substrates derived from human iPSC-derived lower motor neurons (i3LMNs) is provided. A live-cell, longitudinal imaging assay is used to monitor engulfment of human synaptosomes labeled with a pH-sensitive dye, allowing for investigations of iMG's phagocytic capacity. The protocols described herein are broadly applicable to different fields that are investigating human microglia biology and the contribution of microglia to disease.

Nuclear Receptor Small Heterodimer Partner (SHP) Regulates Hepatic Macrophage Differentiation Through Posttranscriptional Regulation of PPARg

BackgroundHepatic macrophages, consisting of resident Kupffer cells and infiltrating monocyte‐derived macrophages (MDMs), are central players of innate immunity involved in hepatic inflammation. The significance of macrophage differentiation towards M1‐like pro‐inflammatory or M2‐like anti‐inflammatory phenotypes in liver inflammatory diseases is widely appreciated; however, the mechanisms controlling this process are not well understood. SHP is a negative regulator of inflammatory signaling. We recently found that Shpis downregulated in M1 and upregulated in M2‐like macrophages, linking Shp to the regulation of macrophage differentiation. In this study, we uncovered a novel regulatory network consisting of Shp, miR‐34a, and peroxisome proliferator–activated receptor gamma (Pparg) in hepatic macrophage differentiation.MethodsWe generated transgenic mice by knocking out Shp from the cells of myeloid origin using Lyz2‐Cre (Shp‐MKO represents Shpflox/flox; Lyz2‐Cre positive). The littermates Lyz2‐Cre negative mice were used as wild‐type controls (WT represents Shpflox/flox; Lyz2‐Cre negative). The in vitro M1 and M2 macrophage differentiation was conducted using primary hepatic macrophages isolated from WT and Shp‐MKO mice and RAW 264.7 mouse macrophage cell line overexpressing Shp(RAW‐Shp). Lipopolysaccharide (LPS) was injected into WT and Shp‐MKO mice to induce acute liver inflammation. Hepatic non‐parenchymal cells were isolated by liver perfusion and subjected to Flow Cytometry to determine immune cell heterogeneity. Hepatic infiltrating CD11b+ MDMs were isolated using microbeads followed by determination of inflammatory gene expression by qPCR.ResultsThe in vitro macrophage differentiation study showed that Shp deletion promoted M1‐like but interfered M2‐like macrophage polarization. In contrast, Shp‐overexpression inhibited M1‐like polarization of RAW‐Shp cells. Flow cytometry analysis revealed a significant increase in the infiltration of CD11b+ MDMs into the liver of Shp‐MKO in comparison to WT after LPS injection. Additionally, the percentage of pro‐inflammatory CD11b+Ly6c+MDMs population doubled in Shp‐MKO liver after LPS treatment. Accordingly, LPS injection significantly induced hepatic Tnfa and Ccl2expressions in Shp‐MKO, which supports the overall increase in hepatic infiltration of pro‐inflammatory macrophages observed in Shp‐MKO. On the molecular level, SHP overexpression significantly induced Pparg, the master regulator of M2‐like macrophage polarization. To explore the molecular basis of Shp regulation of Pparg, we performed small RNA sequencing of Shp‐knockout liver. A total of 53 different microRNAs (miRNAs) were upregulated in Shp‐knockout liver. Using miRNA target prediction tool, we found that 5 of these upregulated miRNAs (miR‐34a, mir‐27a, miR‐130b, miR‐673, miR‐540) can target Pparg‐3´‐UTR. We confirmed that miR‐34a‐5p, the negative regulator of Pparg, was increased in Shp deficient macrophages but decreased in Shpoverexpressing macrophages.ConclusionOur study revealed a previously unknown role of SHP in macrophage differentiation. We found that Shp promotes the anti‐inflammatory macrophage differentiation by posttranscriptional regulation of Pparg through inhibition of miR‐34a. Targeting SHP may be useful for developing effective treatment for liver inflammatory diseases.

Hexokinase 3 enhances myeloid cell survival via non-glycolytic functions

The family of hexokinases (HKs) catalyzes the first step of glycolysis, the ATP-dependent phosphorylation of glucose to glucose-6-phosphate. While HK1 and HK2 are ubiquitously expressed, the less well-studied HK3 is primarily expressed in hematopoietic cells and tissues and is highly upregulated during terminal differentiation of some acute myeloid leukemia (AML) cell line models. Here we show that expression of HK3 is predominantly originating from myeloid cells and that the upregulation of this glycolytic enzyme is not restricted to differentiation of leukemic cells but also occurs during ex vivo myeloid differentiation of healthy CD34+ hematopoietic stem and progenitor cells. Within the hematopoietic system, we show that HK3 is predominantly expressed in cells of myeloid origin. CRISPR/Cas9 mediated gene disruption revealed that loss of HK3 has no effect on glycolytic activity in AML cell lines while knocking out HK2 significantly reduced basal glycolysis and glycolytic capacity. Instead, loss of HK3 but not HK2 led to increased sensitivity to ATRA-induced cell death in AML cell lines. We found that HK3 knockout (HK3-null) AML cells showed an accumulation of reactive oxygen species (ROS) as well as DNA damage during ATRA-induced differentiation. RNA sequencing analysis confirmed pathway enrichment for programmed cell death, oxidative stress, and DNA damage response in HK3-null AML cells. These signatures were confirmed in ATAC sequencing, showing that loss of HK3 leads to changes in chromatin configuration and increases the accessibility of genes involved in apoptosis and stress response. Through isoform-specific pulldowns, we furthermore identified a direct interaction between HK3 and the proapoptotic BCL-2 family member BIM, which has previously been shown to shorten myeloid life span. Our findings provide evidence that HK3 is dispensable for glycolytic activity in AML cells while promoting cell survival, possibly through direct interaction with the BH3-only protein BIM during ATRA-induced neutrophil differentiation.

A Comprehensive Immune Cell Atlas of Cystic Kidney Disease Reveals the Involvement of Adaptive Immune Cells in Injury-Mediated Cyst Progression in Mice.

Inducible disruption of cilia-related genes in adult mice results in slowly progressive cystic disease, which can be greatly accelerated by renal injury. To identify in an unbiased manner modifier cells that may be influencing the differential rate of cyst growth in injured versus non-injured cilia mutant kidneys at a time of similar cyst severity, we generated a single-cell atlas of cystic kidney disease. We conducted RNA-seq on 79,355 cells from control mice and adult-induced conditional Ift88 mice (hereafter referred to as cilia mutant mice) that were harvested approximately 7 months post-induction or 8 weeks post 30-minute unilateral ischemia reperfusion injury. Analyses of single-cell RNA-seq data of CD45+ immune cells revealed that adaptive immune cells differed more in cluster composition, cell proportion, and gene expression than cells of myeloid origin when comparing cystic models with one another and with non-cystic controls. Surprisingly, genetic deletion of adaptive immune cells significantly reduced injury-accelerated cystic disease but had no effect on cyst growth in non-injured cilia mutant mice, independent of the rate of cyst growth or underlying genetic mutation. Using NicheNet, we identified a list of candidate cell types and ligands that were enriched in injured cilia mutant mice compared with aged cilia mutant mice and non-cystic controls that may be responsible for the observed dependence on adaptive immune cells during injury-accelerated cystic disease. Collectively, these data highlight the diversity of immune cell involvement in cystic kidney disease.

LILRB4, an immune checkpoint on myeloid cells.

Leukocyte immunoglobulin-like receptor B4 (LILRB4) is an inhibitory receptor in the LILR family mainly expressed on normal and malignant human cells of myeloid origin. By binding to ligands, LILRB4 is activated and subsequently recruits adaptors to cytoplasmic immunoreceptor tyrosine inhibitory motifs to initiate different signaling cascades, thus playing an important role in physiological and pathological conditions, including autoimmune diseases, microbial infections, and cancers. In normal myeloid cells, LILRB4 regulates intrinsic cell activation and differentiation. In disease-associated or malignant myeloid cells, LILRB4 is significantly correlated with disease severity or patient survival and suppresses T cells, thereby participating in the pathogenesis of various diseases. In summary, LILRB4 functions as an immune checkpoint on myeloid cells and may be a promising therapeutic target for various human immune diseases, especially for cancer immunotherapy.

IDO Vaccine Ablates Immune-Suppressive Myeloid Populations and Enhances Antitumor Effects Independent of Tumor Cell IDO Status.

The immunosuppressive tumor microenvironment (TME) does not allow generation and expansion of antitumor effector cells. One of the potent immunosuppressive factors present in the TME is the indoleamine-pyrrole 2,3-dioxygenase (IDO) enzyme, produced mainly by cancer cells and suppressive immune cells of myeloid origin. In fact, IDO+ myeloid-derived suppressor cells (MDSC) and dendritic cells (DC) tend to be more suppressive than their IDO- counterparts. Hence, therapeutic approaches that would target the IDO+ cells in the TME, while sparing the antigen-presenting functions of IDO- myeloid populations, are needed. Using an IDO-specific peptide vaccine (IDO vaccine), we explored the possibility of generating effector cells against IDO and non-IDO tumor-derived antigens. For this, IDO-secreting (B16F10 melanoma) and non-IDO-secreting (TC-1) mouse tumor models were employed. We showed that the IDO vaccine significantly reduced tumor growth and enhanced survival of mice in both the tumor models, which associated with a robust induction of IDO-specific effector cells in the TME. The IDO vaccine significantly enhanced the antitumor efficacy of non-IDO tumor antigen-specific vaccines, leading to an increase in the number of total and antigen-specific activated CD8+ T cells (IFNγ+ and granzyme B+). Treatment with the IDO vaccine significantly reduced the numbers of IDO+ MDSCs and DCs, and immunosuppressive regulatory T cells in both tumor models, resulting in enhanced therapeutic ratios. Together, we showed that vaccination against IDO is a promising therapeutic option for both IDO-producing and non-IDO-producing tumors. The IDO vaccine selectively ablates the IDO+ compartment in the TME, leading to a significant enhancement of the immune responses against other tumor antigen-specific vaccines.