Immune Cells In Bone Marrow Research Articles

Exposure to elevated cholesterol results in a non-reversible epigenetic and metabolic shift in macrophages associated with increased residual inflammatory risk

Abstract Almost all patients with or at high risk of atherosclerosis are treated with statin therapy. However, there remains a high burden of cardiovascular risk in these patients. Indeed, it is now clear that residual inflammatory risk is a stronger predictor of cardiovascular events, cardiovascular death, and all-cause death than residual cholesterol risk (as measured by low-density lipoprotein cholesterol). Therefore, in this study we sought to better understand the origin of inflammatory residual risk associated with previous exposure to high cholesterol. Tissue resident macrophages and bone marrow derived macrophages (BMDM) from mice which have been exposed to high cholesterol display an augmented polarisation profile. BMDM’s generated ex vivo are grown under standard condition so any effects come from in vivo exposure to high cholesterol. BMDMs from high cholesterol mice display a heighten M1 and blunted M2-like phenotype. Metabolomic analysis of M(IL-4) macrophages reveal they have breaks in the TCA cycle resulting in reduced capacity to utilise OxPhos which is needed for full M(IL-4) polarisation. Macrophages from chimeric mice generated by bone marrow transfer of high cholesterol bone marrow into irradiated normo-cholesterol mice retain the same phenotype as macrophages from high-cholesterol mice. Critically we demonstrate that there are genome wide irreversible epigenetic changes in bone marrow cells and tissue resident macrophages as a result of exposure to high cholesterol. Mice from a high cholesterol background have an increased number of total HSC (lin-ckit+sca1+) within the bone marrow, however, there is a decreased in the total number of long term (LT)-HSC; critically, this phenotype is not reversible when lipids levels are normalised using monoclonal antibody therapy against PCSK9. This is coupled with an irreversible myeloid skewing in the bone marrow immune cell composition. Newly recruited macrophages within the adipose also retain a heighten M1 and blunted M2-like phenotype despite lipid normalisation conferring a negative systemic metabolic phenotype. Critically, these data show that cholesterol induces long term epigenetic and metabolic changes to HSC and macrophages, which may account for residual inflammatory risk.

Maternal thirdhand exposure to e-cigarette vapor alters lung and bone marrow immune cell responses in offspring in the absence or presence of influenza infection.

There is increasing evidence that thirdhand exposure to e-cigarette vapor (e-vapor) can have detrimental effects on the lungs. However, whether maternal exposure during pregnancy results in harmful changes to the offspring is unknown. Using two different e-cigarette settings (low vs. high power), BALB/c mice were subjected to thirdhand e-vapor (e-vapor deposited onto towels, towels changed daily) in the absence or presence of nicotine, before, during, and after pregnancy. Male adult offspring were then infected with mouse-adapted influenza A virus (A/PR/8/34 H1N1; Flu) and lung and bone marrow immune cell responses were assessed 7 days postinfection. Maternal thirdhand exposure to low-power (MLP) or high-power (MHP) e-vapor with nicotine (MLP + NIC and MHP + NIC, respectively) increased the percentage of lung immune cells and neutrophils in the bone marrow. Interestingly, Flu-infected offspring from MLP + NIC and MHP + NIC groups had lower percentages of lung alveolar macrophages and more pronounced increases in neutrophils in the bone marrow, when compared with offspring from MSham Flu controls. Flu infection also decreased the percentage of lung CD4+ T cells and increased the percentage of lung CD8+ T cells, irrespective of maternal exposure (MLP -/+ NIC and MHP -/+ NIC). Significantly, both MLP + NIC and MHP + NIC resulted in blunted activation of lung CD4+ T cells, but only MLP + NIC caused blunted activation of lung CD8+ T cells. Together, we show for the first time that maternal thirdhand exposure to e-vapor results in significant, long-lived effects on lung and bone marrow immune cell responses in offspring at baseline and response to Flu infection.NEW & NOTEWORTHY Maternal exposure to environmental residues of e-cigarette use has significant effects on immune cell responses in the lungs and bone marrow of offspring at both baseline and in response to influenza A virus (Flu) infection.

Establishment and verification of a TME prognosis scoring model based on the acute myeloid leukemia single-cell transcriptome

The tumor microenvironment (TME) plays an important role in the occurrence and progression of Acute Myeloid Leukemia (AML). Single-cell sequencing has enabled researchers to explore the correlation between TME subgroups and tumor prognosis, distinguish the existence of drug-resistant subgroups of tumor cells, and unravel the complexity of the AML cellular heterogeneity. We used bone marrow immune cell enrichment analysis from public databases to screen prognostic genes, construct prognostic models, and validate their prognostic significance on independent external datasets and patient samples. A total of 18,251 single cells were obtained to establish prognostic scoring models for 10 key genes including CCL5, ETLS2, and IL2RA.The AML cases were divided into two groups: high-risk and low-risk. The low-risk group exhibited a higher survival rate than the high-risk group. The areas under curves (AUC) of 1-, 3- and 5-year survival curves in the TCGA and GEO training sets were greater than 0.8 and 0.6, respectively, indicating effective prediction. The model’s prognostic efficacy was confirmed across multiple validation sets. It demonstrated increased expression of ETS2, CCL5, and IL2RA in AML samples compared to controls, which was associated with decreased overall survival (OS). This prognostic scoring model based on tumor immune infiltration provides a reference for developing novel treatment strategies for recurrent/refractory AML.

Targeting the glucocorticoid receptor-CCR8 axis mediated bone marrow T cell sequestration enhances infiltration of anti-tumor T cells in intracranial cancers.

Brain tumors such as glioblastomas are resistant to immune checkpoint blockade therapy, largely due to limited T cell infiltration in the tumors. Here, we show that mice bearing intracranial tumors exhibit systemic immunosuppression and T cell sequestration in bone marrow, leading to reduced T cell infiltration in brain tumors. Elevated plasma corticosterone drives the T cell sequestration via glucocorticoid receptors in tumor-bearing mice. Immunosuppression mediated by glucocorticoid-induced T cell dynamics and the subsequent tumor growthpromotion can be abrogated by adrenalectomy, the administration of glucocorticoid activationinhibitors or glucocorticoid receptor antagonists, and in mice with T cell-specific deletion of glucocorticoid receptor. CCR8 expression in T cells is increased in tumor-bearing mice in a glucocorticoid receptor-dependent manner. Additionally, chemokines CCL1 and CCL8, the ligands for CCR8, are highly expressed in bone marrow immune cells in tumor-bearing mice to recruit T cells. These findings suggested that brain tumor-induced glucocorticoid surge and CCR8 upregulation in T cells lead to T cell sequestration in bone marrow, impairing the anti-tumor immune response. Targeting the glucocorticoid receptor-CCR8 axis may offer a promising immunotherapeutic approach for the treatment of intracranial tumors.

PMN-MDSC: A Culprit Behind Immunosenescence and Increased Susceptibility to Clostridioides difficile Infection During Aging

Susceptibility to pathogens in the elderly is heightened with age, largely because of immunosenescence. As an immune regulatory organ, bone marrow creates immune cells that move to other organs and tissues through the blood. Despite the significance of this process of this organ, there is limited research on changes in immune cell generation in the bone marrow and their effects on immunosenescence. In this study, the compositions of immune cells in bone marrow from young (three months) and old (24+ months) mice were compared by means of mass cytometry, with further validation obtained through the reanalysis of single-cell RNA sequencing data and cell sorting via flow cytometry. The effects of differential immune cells on immunosenescence in old mice were evaluated using the Clostridioides difficile (C. difficile) infection model. Our results showed that aged mice presented with a reduction in bone trabeculae structure, which was accompanied by a notable increase in polymorphonuclear (PMN)-myeloid-derived suppressor cell (MDSC) abundance. Through bulk-seq and reverse transcription quantitative polymerase chain reaction (RT-qPCR) analysis, we identified differential genes associated with the immune response—specifically, the Th17 cell differentiation pathway. Furthermore, the increase in exported PMN-MDSCs to the large intestine resulted in increased gut permeability and inflammatory damage to the colon following C. difficile infection. After clearing the PMN-MDSCs in old mice using the anti-Gr-1 antibody, the symptoms induced by C. difficile were significantly relieved, as evidenced by an inhibited IL-17 pathway in the colon and reduced gut permeability. In conclusion, aging increases the number of PMN-MDSCs in both the generated bone marrow and the outputted intestine, which contributes to susceptibility to C. difficile infection. This study provides a novel target for anti-aging therapy for immunosenescence, which is beneficial for improving immune function in elders.

Identification of potential immune-related mechanisms related to the development of multiple myeloma.

Although significant advances have been made in the treatment of multiple myeloma (MM), leading to unprecedented response and survival rates among patients, the majority eventually relapse, and a cure remains elusive. This situation is closely related to an incomplete understanding of the immune microenvironment, especially monocytes/macrophages in patients with treatment-naïve MM. The aim of this study was to provide insight into the immune microenvironment, especially monocytes/macrophages, in patients with treatment-naïve MM. This study used the single-cell RNA sequencing (scRNA-seq) data of both patients with MM and heathy donors to identify immune cells, including natural killer (NK) cells, T cells, dendritic cells (DCs), and monocytes/macrophages. Transcriptomic data and flow cytometry analysis of monocytes/macrophages were used to further examine the effect of monocytes/macrophages in treatment-naïve MM patients. A significant difference was observed between the bone marrow (BM) immune cells of the healthy controls and treatment-naïve MM patients through scRNA-seq. It is noteworthy that, through an scRNA-seq data analysis, this study found that interferon (IFN)-induced NK/T cells, terminally differentiated effector memory (TEMRA) cells, T-helper cells characterized by expression of IFN-stimulated genes (ISG + Th cells), IFN-responding exhausted T cells, mannose receptor C-type 1 (MRC1) + DCs, IFN-responding DCs, MHCII + DCs, and immunosuppressive monocytes/macrophages were enriched in patients with treatment-naïve MM. Significantly, transcriptomic data of monocytes/macrophages demonstrated that "don't eat me"-related genes and IFN-induced genes increase in treatment-naïve MM patients. Furthermore, scRNA-seq, transcriptomic data, and flow cytometry also showed an increased proportion of CD16 + monocytes/macrophages and expression level of CD16. Cell-cell communication analysis indicated that monocytes/macrophages, whose related important signaling pathways include migration inhibitory factor (MIF) and interleukin 16 (IL-16) signaling pathway, are key players in treatment-naïve MM patients. Our findings provide a comprehensive and in-depth molecular characterization of BM immune cell census in MM patients, especially for monocytes/macrophages. Targeting macrophages may be a novel treatment strategy for patients with MM.

Dietary restriction plus exercise change gene expression of Cxcl12 abundant reticular cells in female mice.

Low energy availability due to excessive exercise lowers bone mass and impairs various physiological functions, including immunity and hematopoiesis. We focused on Cxcl12 abundant reticular (CAR) cells, which are bone marrow mesenchymal stem cells and are essential for the maintenance of hematopoietic and immune cells in bone marrow. We examine the functional changes in CAR cells resulting from dietary restriction combined with exercise. Five-week-old wild-type female mice were divided into an ad libitum group (CON), a 60% dietary restriction group (DR), an ad libitum with exercise group (CON + ex), and a 60% dietary restriction with exercise group (DR + ex). Blood parameters, bone structure parameters, and bone marrow fat volume were evaluated after 5weeks. In addition, bone marrow CAR cells were isolated by cell sorting and analyzed for gene expression by RT-qPCR. Bone mineral density (BMD) was significantly decreased in DR and DR + ex compared to CON and CON + ex. Especially, cortical bone mass and thickness were significantly decreased in DR and DR + ex groups, whereas trabecular bone mass was significantly increased. Bone marrow fat volume was significantly increased in DR and DR + ex groups compared to CON and CON + ex. The number of leukocytes in the blood was significantly decreased in the DR + ex group compared to the other three groups. RT-qPCR showed a significant decrease in gene expression of both Foxc1 and Runx2 in CAR cells of the DR + ex group compared to CON. Dietary restriction combined with exercise promotes CAR cell differentiation into bone marrow adipocyte and suppresses osteoblast differentiation.

Immune profiles to predict bortezomib-based treatment response for multiple myeloma patients

BackgroundTo evaluate the distribution of bone marrow immune cell subsets and their correlation with treatment efficacy in patients with multiple myeloma (MM). MethodsWe analyzed the bone marrow lymphocyte subsets of 186 newly diagnosed MM patients at diagnosis and their correlation with clinical characteristics. In our study, eight-color flow cytometry, a method commonly used to detect plasma cell phenotypes, was used to analyze seven bone marrow immune cell groups by change gate-strategy. ResultsFirst, for all the 7 immune cell groups, the percentage of immature B cells was significantly lower in stage III patients than in stage I patients, while the trend was reversed in memory B cells in both the International Staging System(p = 0.004) and Revised International Staging System(p = 0.018). Second, the percentage of naïve B cells were significantly lower in patients with severe anemia, while the percentage of memory B cells had reversed trend. The percentage of immature B cells were lower in patients with Cr ≥ 2 mg/dL than in patients with Cr < 2 mg/dL. Then we followed the treatment efficacy of 152 patients who received four cycles of induction therapy (bortezomib + dexamethasone or bortezomib + lenalidomide + dexamethasone) and analyzed the relationship between bone marrow lymphocyte subsets at the initial stage and treatment response datasets. We found that both the percentage of B cells(p＜0.001) and immature B(p = 0.002) were increased in patients who achieved very good partial remission(VGPR) after four cycles of induction therapy. The ROC results indicated the combination of the multiple immune subgroups had predictive values (AUC = 0.802, p<0.001) in the treatment effect after four cycles of induction therapy. ConclusionsOverall, these results suggest that the analysis of lymphocyte subsets along with plasma cell immunophenotyping could be a potential index for determining the prognosis of MM patients.

Diet-induced obesity reduces bone marrow T and B cells and promotes tumor progression in a transplantable Vk*MYC model of multiple myeloma

Obesity is associated with an increased risk of developing multiple myeloma (MM). The molecular mechanisms causing this association is complex and incompletely understood. Whether obesity affects bone marrow immune cell composition in multiple myeloma is not characterized. Here, we examined the effect of diet-induced obesity on bone marrow immune cell composition and tumor growth in a Vk*MYC (Vk12653) transplant model of multiple myeloma. We find that diet-induced obesity promoted tumor growth in the bone marrow and spleen and reduced the relative number of T and B cells in the bone marrow. Our results suggest that obesity may reduce MM immune surveillance and thus may contribute to increased risk of developing MM.

Single-Cell RNA Sequencing Identifies Distinct Immune Microenvironment in Patients with Primary Plasma Cell Leukemia

Background: Primary plasma cell leukemia (PCL) is a highly aggressive form of multiple myeloma (MM). While recent advances in cellular immunotherapy have significantly improved the outcome of patients with MM, these benefits have been limited for PCL patients, and their survival remains poor. This is in partly attributable to our limited understanding of the dysregulated immune microenvironment in PCL. Furthermore, distinct biological features of PCL compared with MM have not been clearly defined. In this regard, we performed single-cell RNA sequencing of bone marrow (BM) immune cells and tumor cells from patients with MM and PCL at diagnosis and compared them with BM immune cells from healthy donors. Methods: Single-cell analysis was performed using 10X Genomics with BM mononuclear cells (BMMCs) isolated from healthy donors (n=3), MM patients (n=2), PCL patients with lower circulating plasma cells (5-20%) (PCL-1) (n=2), and PCL patients with higher circulating plasma cells (&amp;gt;20%) (PCL-2) (n=2) at diagnosis. Sequencing files were processed with CellRanger (10x Genomics) and the data were analyzed with the Seurat toolkit. Cell types were annotated with SingleR based on the Human Primary Cell Atlas built-in references. Pre-B cells, B cells, plasmablasts, plasma cells, granulocyte/macrophage progenitors (GMPs), hematopoietic stem and progenitor cells (HSPCs), myeloid dendritic cells (mDCs) and plasmacytoid dendritic cells (pDCs), classical monocytes, non-classical monocytes, T cells, natural killer (NK) cells, and stromal cells between healthy donors, MM, PCL-1, and PCL-2 were annotated. Results: We sequenced a total of 85,268 BMMCs to analyze the heterogeneity and transcriptomic features of BMMCs from healthy, MM, and PCL patients. We characterized changes in the transcriptomic features of T cells, NK cells, monocytes, and DCs between healthy, MM, PCL-1, and PCL-2. We examined CD8 + and CD4 + T cell subsets based on differentiation status, including CCR7 + CD45RA + naïve (TN), CCR7 + CD45RA − central memory T (TCM), CCR7 − CD45RA − effector memory (TEM), and CCR7 − CD45RA + terminally differentiated effector memory T (TEMRA) cells. The proportion of CD8 + TN was decreased in MM, PCL-1, and PCL-2 compared with healthy, while the proportion of TEM was increased in MM and PCL-2 compared with healthy. Of note, the proportion of CD8 + NKG7 + cells was highest in PCL-2, followed by PCL-1 and MM, which were minimally detected in healthy. Among CD4 + T cells, the proportion of regulatory T cells did not differ between the groups. However, cytotoxic CD4 + T cells was increased in MM, PCL-1, and PCL-2 compared with healthy. Analysis of NK cells revealed that the proportion of immature NK cells was decreased, while the proportion of mature NK cells was increased in patients with MM, PCL-1, and PCL-2 compared with healthy. We also examined the plasma cells and observed that diversity in plasma cell types is increased in PCL-1 and PCL-2 compared with MM, indicating that the PCL clone is heterogeneous. Conclusion: We demonstrate the characteristics of BM immune cells in PCL by single-cell RNA sequencing. Additional analyses are ongoing to uncover the association between PCL burden and BM immune cell composition and to gain insight into PCL heterogeneity and define high-risk PCL. Our work should improve our understanding to decipher therapeutic options for PCL.

Limitations of PLX3397 as a microglial investigational tool: peripheral and off-target effects dictate the response to inflammation.

Microglia, the resident macrophages of the central nervous system (CNS), play a critical role in CNS homeostasis and neuroinflammation. Pexidartinib (PLX3397), a colony-stimulating factor 1 (CSF1) receptor inhibitor, is widely used to depletemicroglia, offering flexible options for both long-term depletion andhighly versatile depletion-repopulation cycles. However, the potential impact of PLX3397 on peripheral (immune) cells remains controversial. Until now, the microglia-specificity of this type of compounds has not been thoroughly evaluated, particularly in the context of peripherally derived neuroinflammation. Our study addresses this gap by examining the effects of PLX3397 on immune cells in the brain, liver, circulation and bone marrow, both in homeostasis and systemic inflammation models. Intriguingly, we demonstrate that PLX3397 treatment not only influences the levels of tissue-resident macrophages, but also affects circulating and bone marrow immune cells beyond the mononuclear phagocyte system (MPS). These alterations in peripheral immune cells disrupt the response to systemic inflammation, consequently impacting the phenotype irrespective of microglial depletion. Furthermore, we observed that a lower dose of PLX3397, which does not deplete microglia, demonstrates similar (non-)MPS effects, both in the periphery and the brain, but fails to fully replicate the peripheral alterations seen in the higher doses, questioning lower doses as a 'peripheral control' strategy. Overall, our data highlight the need for caution when interpreting studies employing this compound, as it may not be suitable for specific investigation of microglial function in the presence of systemic inflammation.

The Influence of Maternal High Fat Diet During Lactation on Offspring Hematopoietic Priming.

Obesity and metabolic diseases are rising among women of reproductive age, increasing offspring metabolic risk. Maternal nutritional interventions during lactation present an opportunity to modify offspring outcomes. We previously demonstrated in mice that adult male offspring have metabolic impairments and increased adipose tissue macrophages (ATM) when dams are fed high fat diet (HFD) during the postnatal lactation window (HFD PN). We sought to understand the effect of HFD during lactation on early-life inflammation. HFD PN offspring were evaluated at postnatal day 16 to 19 for tissue weight and gene expression. Profiling of adipose tissue and bone marrow immune cells was conducted through lipidomics, in vitro myeloid colony forming unit assays, and flow cytometry. HFD PN mice had more visceral gonadal white adipose tissue (GWAT) and subcutaneous fat. Adipose tissue RNA sequencing demonstrated enrichment of inflammation, chemotaxis, and fatty acid metabolism and concordant changes in GWAT lipidomics. Bone marrow (BM) of both HFD PN male and female offspring had increased monocytes (CD45+Ly6G-CD11b+CD115+) and B cells (CD45+Ly6G-CD11b-CD19+). Similarly, serum from HFD PN offspring enhanced in vitro BM myeloid colonies in a toll-like receptor 4-dependent manner. We identified that male HFD PN offspring had increased GWAT pro-inflammatory CD11c+ ATMs (CD45+CD64+). Maternal exposure to HFD alters milk lipids enhancing adiposity and myeloid inflammation even in early life. Future studies are needed to understand the mechanisms driving this pro-inflammatory state of both BM and ATMs, the causes of the sexually dimorphic phenotypes, and the feasibility of intervening in this window to improve metabolic health.

Bone Marrow-Derived GCA+ Immune Cells Drive Alzheimer's Disease Progression.

Alzheimer's disease (AD) is an age-related degenerative disease of the central nervous system (CNS), whereas the role of bone marrow immune cells in the pathogenesis of AD remains unclear. Here, the study reveals that compared to matched healthy individuals, AD patients have higher circulating grancalcin (GCA) levels, which negatively correlate with cognitive function. Bone marrow-derived GCA+ immune cells, which secret abundant GCA and increase during aging, preferentially invaded the hippocampus and cortex of AD mouse model in a C-C Motif Chemokine Receptor 10 (CCR10)-dependent manner. Transplanting GCA+ immune cells or direct stereotaxic injection of recombinant GCA protein intensified amyloid plaque load and aggravated cognitive and memory impairments. In contrast, genetic ablation of GCA in the hematopoietic compartment improves cognitive and memory function. Mechanistically, GCA competitively binds to the low-density lipoprotein receptor-related protein 1 (LRP1) in microglia, thus inhibiting phagocytosis and clearance of Aβ and potentiating neuropathological changes. Importantly, GCA-neutralizing antibody treatment rejuvenated cognitive and memory function and constrained AD progression. Together, the study demonstrates a pathological role of GCA+ immune cells instigating cognitive and memory decline, suggesting that GCA+ immune cells can be a potential target for innovative therapeutic strategies in AD.

Single-Cell RNA Sequencing Reveals Hypo-Responsiveness of T and NK Cells to Interferon Stimulation As an Immune Hallmark in Asymptomatic Waldenstrom's Macroglobulinemia

Introduction Waldenstrom macroglobulinemia (WM) is a rare, indolent non-Hodgkin lymphoplasmacytic lymphoma of the bone marrow (BM), characterized by monoclonal IgM protein production. WM is preceded by IgM monoclonal gammopathy of undetermined significance (IgM MGUS) and smoldering WM (SWM), which are clinically detectable but asymptomatic precursor phases (collectively referred to as asymptomatic WM; AWM). Recent work has revealed significant changes in the immune microenvironment of patients with overt WM, however, less is known about immune dysregulation in patients with early-stage disease. Methods We performed 5' single-cell RNA sequencing (scRNAseq) on BM immune cells from patients with AWM (n=28), healthy donors (HD, n=23), and patients with smoldering multiple myeloma (SMM) (n=27). We also performed an in vitro stimulation experiment using universal Type I interferon (IFN) and subsequent scRNAseq on bone marrow mononuclear cells (BMMCs) and peripheral blood mononuclear cells (PBMCs) from AWM (n=3) and HD (n=3). Results Overall, we annotated 210,019 immune cells, excluding normal B cells. Despite their early stage, AWM patients showed significantly altered BM immune cell composition, including increased proportions of CD56dim NK cells, CD8+ effector memory cells, and CD16 + Monocytes and decreased proportions of pro-inflammatory CD14 + monocytes and activated and interferon (IFN)-stimulated T and NK cells (q&amp;lt;0.2). Low-risk AWM presented similar changes in immune cell composition as intermediate- and high-risk AWM, implying that compositional alterations may be established early in the disease course. Notably, however, the proportion of Tregs was significantly increased in patients with SWM compared to IgM MGUS (p=0.04), suggesting that Tregs may play a role in disease progression. Next, we compared BM immune cell composition between patients with AWM and SMM. In both tumor types, patients showed significantly higher proportions of CD56dim NK cells and CD16 + monocytes compared to healthy donors. However, strikingly, a significant decrease in activated and IFN-stimulated T and NK cells was only observed in AWM, suggesting it may be a hallmark of disease. Comparison of BMMCs and PBMCs from patients with AWM following in vitro culture revealed that the lack of IFN-stimulated cells was systemic-in both BMMCs and PBMCs-although the effect was significantly more pronounced in BMMCs than PBMCs. Interestingly, while in vitro stimulation with Type I IFN resulted in the generation of IFN-stimulated T and NK cells in both HD and AWM, the levels of IFN stimulation did not entirely normalize, reproducing the gradient observed in the control samples without in vitro stimulation: AWM BM &amp;lt; AWM PB &amp;lt; HD BM. To test whether the observed defect was due to a lack of IFN in AWM, we next compared the gene expression profile of monocytes from AWM and HD, which revealed significantly higher activity of the IFN signature in monocytes from AWM compared to HD (p &amp;lt; 10 -5). This suggests that IFN levels in patients are at least not reduced. Collectively, these results indicate that T and NK cells from AWM are hypo-responsive to IFN stimulation, despite the presence of normal or possibly increased IFN in the BM microenvironment. Conclusion Our results indicate that despite the absence of symptoms, patients with AWM already have immune dysregulation in the BM, including the absence of IFN-stimulated T and NK cells, which may provide a rationale for therapeutic intervention. Previous studies have demonstrated clinical responses to therapeutic IFN administration, suggesting that novel formulations with improved therapeutic windows may have a role in treating patients with WM in the future.

Bone marrow immune cells stop weight regain

Weight regain is a major challenge in the long-term management of obesity; however, the underlying mechanisms remain unclear. Zhou etal. found that bone-marrow-derived CD7+ monocytes respond to fluctuating nutritional stress and suppress weight regain by promoting beige fat thermogenesis.

Blinatumomab differentially modulates peripheral blood and bone marrow immune cell repertoire: A Campus ALL study.

Blinatumomab is the first bi-specific T-cell engager approved for relapsed or refractory B-cell precursor acute lymphoblastic leukaemia (B-ALL). Despite remarkable clinical results, the effects of blinatumomab on the host immune cell repertoire are not fully elucidated. In the present study, we characterized the peripheral blood (PB) and, for the first time, the bone marrow (BM) immune cell repertoire upon blinatumomab treatment. Twenty-nine patients with B-ALL received blinatumomab according to clinical practice. Deep multiparametric flow cytometry was used to characterize lymphoid subsets during the first treatment cycle. Blinatumomab induced a transient redistribution of PB effector T-cell subsets and Treg cells with a persistent increase in cytotoxic NK cells, which was associated with a transient upregulation of immune checkpoint receptors on PB CD4 and CD8 T-cell subpopulations and of CD39 expression on suppressive Treg cells. Of note, BM immune T-cell subsets showed a broader post-treatment subversion, including the modulation of markers associated with a T-cell-exhausted phenotype. In conclusion, our study indicates that blinatumomab differentially modulates the PB and BM immune cell repertoire, which may have relevant clinical implications in the therapeutic setting.

Bone marrow immune cells respond to fluctuating nutritional stress to constrain weight regain

Weight regain after weight loss is a major challenge in the treatment of obesity. Immune cells adapt to fluctuating nutritional stress, but their roles in regulating weight regain remain unclear. Here, we identify a stem cell-like CD7+ monocyte subpopulation accumulating in the bone marrow (BM) of mice and humans that experienced dieting-induced weight loss. Adoptive transfer of CD7+ monocytes suppresses weight regain, whereas inducible depletion of CD7+ monocytes accelerates it. These cells, accumulating metabolic memories via epigenetic adaptations, preferentially migrate to the subcutaneous white adipose tissue (WAT), where they secrete fibrinogen-like protein 2 (FGL2) to activate the protein kinase A (PKA) signaling pathway and facilitate beige fat thermogenesis. Nevertheless, CD7+ monocytes gradually enter a quiescent state after weight loss, accompanied by increased susceptibility to weight regain. Notably, administration of FMS-like tyrosine kinase 3 ligand (FLT3L) remarkably rejuvenates CD7+ monocytes, thus ameliorating rapid weight regain. Together, our findings identify a unique bone marrow-derived metabolic-memory immune cell population that could be targeted to combat obesity.

Intestinal permeability and peripheral immune cell composition are altered by pregnancy and adiposity at mid- and late-gestation in the mouse.

It is clear that the gastrointestinal tract influences metabolism and immune function. Most studies to date have used male test subjects, with a focus on effects of obesity and dietary challenges. Despite significant physiological maternal adaptations that occur across gestation, relatively few studies have examined pregnancy-related gut function. Moreover, it remains unknown how pregnancy and diet can interact to alter intestinal barrier function. In this study, we investigated the impacts of pregnancy and adiposity on maternal intestinal epithelium morphology, in vivo intestinal permeability, and peripheral blood immunophenotype, using control (CTL) and high-fat (HF) fed non-pregnant female mice and pregnant mice at mid- (embryonic day (E)14.5) and late (E18.5) gestation. We found that small intestine length increased between non-pregnant mice and dams at late-gestation, but ileum villus length, and ileum and colon crypt depths and goblet cell numbers remained similar. Compared to CTL-fed mice, HF-fed mice had reduced small intestine length, ileum crypt depth and villus length. Goblet cell numbers were only consistently reduced in HF-fed non-pregnant mice. Pregnancy increased in vivo gut permeability, with a greater effect at mid- versus late-gestation. Non-pregnant HF-fed mice had greater gut permeability, and permeability was also increased in HF-fed pregnant dams at mid but not late-gestation. The impaired maternal gut barrier in HF-fed dams at mid-gestation coincided with changes in maternal blood and bone marrow immune cell composition, including an expansion of circulating inflammatory Ly6Chigh monocytes. In summary, pregnancy has temporal effects on maternal intestinal structure and barrier function, and on peripheral immunophenotype, which are further modified by HF diet-induced maternal adiposity. Maternal adaptations in pregnancy are thus vulnerable to excess maternal adiposity, which may both affect maternal and child health.

CD73 Dysregulates Monocyte Anti-Tumor Activity in Multiple Myeloma.

Multiple myeloma (MM) is characterized by immune cell dysfunction in the tumor microenvironment (TME). We aimed at evaluating the effect of CD73, an overexpressed factor in some tumors, on anti-tumor immune function in the TME of MM. We analyzed the expression of CD73 in T-, B-, and natural killer (NK)-lymphocytes and monocytes in bone marrow (BM), peripheral blood (PB) from MM patients and healthy controls, and residual CD138+ cells using flow cytometry. The anti-tumor activity of these monocytes was confirmed by co-culture with RPMI-8226 cells treated with a CD73 inhibitor. We determined the interleukin (IL)-2, IL-4, IL-6, IL-10, tumor necrosis factor (TNF)-α, and interferon (IFN)-γ levels using a cytometric bead array. Monocyte phagocytosis in cell culture sediment was then observed and measured. CD73 was highly expressed in T-, B-, and NK-lymphocytes and monocytes from the BM and PB isolated from patients with MM. Compared with healthy controls, MM samples exhibited significantly higher CD73 expression and TNF-α, IFN-γ, IL-10 levels in monocytes. Inhibiting CD73 in BM immune cells from MM samples significantly increased the secretion of IL-2, TNF-α, and IFN-γ, as well as the killing ability of immune cells. However, monocyte phagocytosis was seldom observed. Inhibiting CD73 in MM monocytes significantly increased the secretion of IL-2, TNF-α, and IFN-γ in monocytes and improved monocyte killing and phagocytosis. Monocytes from MM exhibited weakened anti-tumor effects, and CD73 was involved in forming an immunosuppressive microenvironment. Inhibiting CD73 partly restored the anti-tumor activity of monocytes, a potential strategy for the treatment of MM.

Chronic IFNα treatment induces leukopoiesis, increased plasma succinate and immune cell metabolic rewiring

Although clinically effective, the actions of IFNα, either produced endogenously or by therapeutic delivery, remain poorly understood. Emblematic of this research gap is the disparate array of notable side effects that occur in susceptible individuals, such as neuropsychiatric consequences, autoimmune phenomena, and infectious complications. We hypothesised that these complications are driven at least in part by dysregulated cellular metabolism. Male Wistar rats were treated with either 170,000 IU/kg human recombinant IFNα-2a or BSA/saline (0.9% NaCl) three times per week for three weeks. Bone marrow (BM) immune cells were isolated from the excised femurs for glycolytic rate and mitochondrial function assessment using Agilent Seahorse Technology. Frequencies of immune cell populations were assessed by flow cytometry to determine whether leukopoietic changes had occurred in both blood and BM. Plasma levels of lactate and succinate were also determined. BMDMs were metabolically assessed as above, as well as their metabolic response to an antigenic stimulus (iH37Rv). We observed that BM immune cells from IFN-treated rats exhibit a hypermetabolic state (increased basal OCR/GlycoPER) with decreased mitochondrial metabolic respiration and increased non-mitochondrial OCR. Flow cytometry results indicated an increase in immature granulocytes (RP1- SSChi CD45lo) only in the blood, together with increased succinate levels in the plasma. BMDMs from IFN-treated rats retained the hypermetabolic phenotype after differentiation and failed to induce a step-up in glycolysis and mitochondrial respiration after bacterial stimulation. This work provides the first evidence of the effects of IFNα treatment in inducing hypermetabolic immune features that are associated with markers of inflammation, leukopoiesis, and defective responses to bacterial stimulation.