Neutrophil Subsets Research Articles

Abstract 2082: Neutrophil Programming In Atherosclerosis

Emerging evidence suggest the involvement of neutrophils during the progression of human atherosclerosis through secreting inflammatory mediators and causing damages to endothelial vasculature. However, compared to other well-recognized immune cells such as monocytes/macrophages, mechanisms underlying the regulation of neutrophils during atherosclerosis are relatively less studied and understood. This presents a major impediment in our thorough understanding of the pathogenesis of atherosclerosis. In this study, we reported that both murine and human neutrophil population possesses a minor homeostatic resolving subset characterized by reduced expression of inflammatory mediators (LTB4, elastase), elevated expression of anti-inflammatory resolving mediators (RvD1, CD200R), correlated with reduced expression of inflammatory signaling adaptor TRAM. We observed that TRAM deficient neutrophils are effectively reprogrammed into the resolving state, and can potently improve vascular integrity and suppress atherosclerosis pathogenesis when adoptively transfused into recipient atherosclerotic animals. Mechanistically, TRAM deficiency reduces the expression of LOX5AP, dislodges nuclear localization of LOX5, and favors the generation of RvD1 instead of LTB4. We also observed that human TRAM-low neutrophils are less inflammatory, as reflected in reduced swarming and reduced induction of LTB4/elastase. TRAM serves as a stress sensor of oxLDL and/or free cholesterol, triggers inflammatory signaling processes that facilitate elastase release. Our data defines a novel resolving neutrophil subset due to reduced TRAM expression which may hold therapeutic potential for reducing inflammation and treating atherosclerosis.

The different impact of drug-resistant Leishmania on the transcription programs activated in neutrophils

Drug resistance threatens the effective control of infections, including parasitic diseases such as leishmaniases. Neutrophils are essential players in antimicrobial control, but their role in drug-resistant infections is poorly understood. Here, we evaluated human neutrophil response to clinical parasite strains having distinct natural drug susceptibility. We found that Leishmania antimony drug resistance significantly altered the expression of neutrophil genes, some of them transcribed by specific neutrophil subsets. Infection with drug-resistant parasites increased the expression of detoxification pathways and reduced the production of cytokines. Among these, the chemokine CCL3 was predominantly impacted, which resulted in an impaired ability of neutrophils to attract myeloid cells. Moreover, decreased myeloid recruitment when CCL3 levels are reduced was confirmed by blocking CCL3 in a mouse model. Collectively, these findings reveal that the interplay between naturally drug-resistant parasites and neutrophils modulates the infected skin immune microenvironment, revealing a key role of neutrophils in drug resistance.

Neutrophil subsets.

Neutrophil subsets.

Abstract 6806: Single cell RNA sequencing of human and murine cancers demonstrates metastases-specific neutrophil phenotypes driven by the IL-1β/CXCR2 signaling axis - Disruption of this pathway abrogates neutrophil immunosuppressive effects and reduces tumor burden

Abstract Introduction: Neutrophils are a highly heterogenous, plastic cell population, known to play a vital role in the tumor microenvironment and progression of CMS4 colorectal cancer (CRC) metastases. We have performed a comprehensive examination of different neutrophil transcriptional states, through utilization of single-cell RNA sequencing of publicly available and independently generated data across health and malignancy in human and murine disease, and validated findings using in vivo and in vitro models of CMS4 subtype CRC. Methods: Publicly available and independently generated breast, lung and CRC datasets from human disease mouse models were integrated to establish and validate reproducibility of neutrophil-gene signatures, and pseudo-time analysis was used to identify genes driving neutrophil development along a lineage from health to tumor using Seurat on R. Findings were validated in healthy and KrasG12D/+, Trp53fl/fl, Rosa26N1CD/+ (KPN) tumor-bearing wild type or Mrp8CreCxcr2fl/fl genetically engineered mouse models with neutrophil-specific loss of Cxcr2. Results: We have identified distinct neutrophil subtypes in health and primary tumors, preserved in murine and human cancer and across multiple tumor types. In CRC metastases, discrete neutrophil transcriptomic subtypes are identified, with phenotypes from health to those identified in metastases driven by the IL-1β/CXCL8/CXCR2 signalling axis. Assessment of global signalling of single-cell transcripts has identified CD4+ T cells and macrophages as dominant regulators of the metastatic niche. Neutrophils sorted from the metastatic niche strongly suppress T cell proliferation, identifying them as immunosuppressive. Loss of neutrophil-specific Cxcr2 attenuates suppression of T cell proliferation in co-culture with neutrophils from the metastatic niche of tumor-bearing mice. T cell proliferation is unaffected in co-culture with healthy wild type or Cxcr2fl/fl neutrophils. We currently are running orthotopic intrasplenic models to assess the importance of loss of neutrophil-specific Cxcr2 in generation of metastases in vivo in CMS4 CRC. Conclusions: We speculate that ablation of metastasis specific neutrophil subsets in CMS4 CRC in combination with other therapies, may alter the immunosuppressive nature of the immune microenvironment and allow for reduction in tumor burden in metastatic disease. Citation Format: Alistair S. McLaren, Rana Fetit, Mark White, Megan L. Mills, Tamsin Lannagan, John Falconer, Xabier Cortes-Lavaud, Kathryn Gilroy, Rachel Ridgway, Colin Nixon, Varushka Naiker, Renee Njunge, Cassie J. Clarke, Declan Whyte, Kristina Kirschner, Rene Jackstadt, Jim C. Norman, Leo M. Carlin, Andrew D. Campbell, Owen J. Sansom, Colin W. Steele. Single cell RNA sequencing of human and murine cancers demonstrates metastases-specific neutrophil phenotypes driven by the IL-1β/CXCR2 signaling axis - Disruption of this pathway abrogates neutrophil immunosuppressive effects and reduces tumor burden [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6806.

Abstract B086: Novel myeloid activation therapy promotes regression of metastatic ovarian cancer

Abstract Significance: Most ovarian cancer (OC) patients ultimately succumb to drug-resistant intraperitoneal metastases. There is an unmet need to develop novel therapies against metastatic OC. Whether activating myeloid cells can promote OC regression has not been explored extensively. The purpose of this study is to develop a novel immunotherapy that activates myeloid cells with the goal of eradicating metastatic OC. Methods: In this study, we mainly relied on syngeneic mouse models of metastatic OC. To model metastatic OC in mice, we performed intraperitoneal injection of clinically relevant murine OC cell lines that were recently established by Dr. Robert Weinberg’s group, including homologous recombination (HR)-proficient KPCA cells (KRASG12VTrp53R172HCcne1OEAkt2OE ) and HR-deficient BPPNM cells (Brca1−/−Trp53R172HPten−/− Nf1−/−MycOE ). To activate myeloid cells, we used b-glucan and interferon (IFN) γ. b-glucan is a yeast cell wall polysaccharide that is currently in clinical trials to treat multiple cancers (NCT05159778). It canonically activates myeloid cells through the Dectin-1-spleen tyrosine kinase (SYK) pathway and induces infiltration of monocytes and neutrophils. IFNγ activates macrophages to an anti-tumor status. We investigated whether and how b-glucan affects metastatic OC with or without IFNγ using bioluminescence imaging, confocal imaging, flow cytometry, and single-cell RNA sequencing (scRNA seq). Finally, we tested whether combining myeloid cell activation with carboplatin could eradicate metastatic OC.Results: First, we found that b-glucan alone was highly efficient in clearing ascites. b-glucan captured free-floating OC cells into solid nodules within 5 hours after its injection through two non-redundant and equally important pathways: (1) an unexpected Dectin-1-SYK-independent, heparin-sensitive pathway that was mediated by resident macrophages in the peritoneal fluid; (2) a Dectin-1-SYK-PAD4-dependent pathway that was mediated by neutrophil extracellular traps in the omentum. Second, we found that combining b-glucan with IFNγ (b-glucan/IFNγ) not only cleared ascites but also reduced total metastases compared to PBS-, b-glucan-, or IFNγ-treated mice. This anti-tumor immunity required T cells and non-tumor IFNγ signaling in the host. Third, using scRNA seq, we found that b-glucan/IFNγ induced the enrichment of unique subsets of tumoricidal neutrophils and macrophages compared to other groups. Interestingly, the novel macrophage subset selectively expressed an interleukin (IL)-12 family cytokine, IL-27. We found that blocking IL-27 significantly impaired the anti-tumor response. Finally, combining b-glucan/IFNγ with carboplatin nearly eradicated chemoresistant KPCA tumors and chemosensitive BPPNM tumors. Patients with high expression of the genes identified in the novel myeloid cell subsets correlate with better overall survival. Conclusion: We have identified a novel combination therapy of myeloid activation and chemotherapy that could potentially transform treatments against metastatic OC. Citation Format: Brennah Murphy, Taito Miyamoto, Bryan Manning, Toshitha Kannan, Anastasia Ghilkovsky, Yulia Nefedova, Daniel Claiborne, Rugang Zhang, Andrew Kossenkov, Nan Zhang. Novel myeloid activation therapy promotes regression of metastatic ovarian cancer [abstract]. In: Proceedings of the AACR Special Conference on Ovarian Cancer; 2023 Oct 5-7; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(5 Suppl_2):Abstract nr B086.

Investigation of the miRNA-mRNA Regulatory Circuits and Immune Signatures Associated with Bronchopulmonary Dysplasia.

Bronchopulmonary dysplasia (BPD) has become a major cause of morbidity and mortality in preterm infants worldwide, yet its pathogenesis and underlying mechanisms remain poorly understood. The present study sought to explore microRNA-mRNA regulatory networks and immune cells involvement in BPD through a combination of bioinformatic analysis and experimental validation. MicroRNA and mRNA microarray datasets were obtained from the Gene Expression Omnibus (GEO) database. Differentially expressed microRNAs (DEMs) were identified in BPD patients compared to control subjects, and their target genes were predicted using miRWalk, miRNet, miRDB, and TargetScan databases. Subsequently, protein-protein interaction (PPI) and functional enrichment analyses were conducted on the target genes. 30 hub genes were screened using the Cytohubba plugin of the Cytoscape software. Additionally, mRNA microarray data was utilized to validate the expression of hub genes and to perform immune infiltration analysis. Finally, real-time PCR (RT-PCR), immunohistochemistry (IHC), and flow cytometry were conducted using a mouse model of BPD to confirm the bioinformatics findings. Two DEMs (miR-15b-5p and miR-20a-5p) targeting genes primarily involved in the regulation of cell cycle phase transition, ubiquitin ligase complex, protein serine/threonine kinase activity, and MAPK signaling pathway were identified. APP and four autophagy-related genes (DLC1, PARP1, NLRC4, and NRG1) were differentially expressed in the mRNA microarray dataset. Analysis of immune infiltration revealed significant differences in levels of neutrophils and naive B cells between BPD patients and control subjects. RT-PCR and IHC confirmed reduced expression of APP in a mouse model of BPD. Although the proportion of total neutrophils did not change appreciably, the activation of neutrophils, marked by loss of CD62L, was significantly increased in BPD mice. Downregulation of APP mediated by miR-15b-5p and miR-20a-5p may be associated with the development of BPD. Additionally, increased CD62L- neutrophil subset might be important for the immune-mediated injury in BPD.

Pan-immune-inflammation value could be a new marker to differentiate between vascular Behçet's disease and non-vascular Behçet's disease.

Behçet's disease etiology is uncertain, and no specific diagnostic markers exist in the laboratory. This retrospective study aimed to evaluate the role of inflammatory and hematological parameters, mainly Pan-Immune-Inflammation-Value (PIV), in predicting vascular Behçet's disease (VBD). A total of 85 patients with VBD and 92 patients without vascular involvement (non-VBD) were included in this study. Neutrophil, monocyte, platelet, and lymphocyte subsets are all included in the PIV, a new blood-based biomarker. The optimal cut-off values for the PIV were determined to be ≥261.6. White blood cell, neutrophil, monocyte, hemoglobin, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration (MCHC), red cell distribution, platelet, plateletcrit, PIV, neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio, sedimentation, c-reactive protein (CRP) values were significantly associated with VBD in univariate analysis. After multivariate analysis, PIV [odds ratio (OR): 2.758; 95% confidence interval (CI): 1.327-5.736; p=0.007] and CRP (OR: 4.029; 95% CI: 1.924-8.438; p<0.001) were found to be a positive predictor for VBD, while MCHC (OR: 0.722; 95% CI: 0.530-0.983; p=0.039) was seen as a negative predictor. Based on our results, PIV, an easily accessible, cost-effective, and new composite biomarker, has a significant predictive value in VBD.

Deciphering the heterogeneity of neutrophil cells within circulation and the lung cancer microenvironment pre- and post-operation

Neutrophils play a crucial role in the immune system within tumor microenvironment. At present, numerous studies have explored the changes of neutrophils’ automatic killing effect and cellular communication with other immune cells under pathological conditions through single-cell sequencing. However, there remains a lack of definite conclusion about the identification criteria of neutrophil subgroups. Here, we collected tumor and para-carcinoma tissues, pre- and postoperative blood from patients with non-small cell lung cancer (NSCLC), and performed single-cell RNA (scRNA) sequencing to evaluate the distribution of neutrophil subgroups. We have developed a computational method of over expression rate (OER) to evaluate the specificity of neutrophil subgroups, in order to target gene panels with potential clinical application value. In addition, OER was used to evaluate specificity of neutrophil subsets in healthy people and patients with various diseases to further validate the feasibility of this evaluation system. As a result, we found the specificity of Neu_ c1_ IL1B and Neu_ c2_ cxcr4 (low) in postoperative blood has increased, while that of IL-7R + neutrophils has decreased, indicating that these groups of cells possibly differentiated or migrated to other subgroups in the state of lung cancer. In addition, seven gene panels (Neu_c3_CST7, RSAD2_Neu, S100A2/Pabpc1_Neu, ISG15/Ifit3_Neu, CD74_Neu, PTGS2/Actg1_Neu, SPP1_Neu) were high specific in all the four NSCLC-associated samples, meaning that changes in the percentage of these cell populations would have a high degree of confidence in assessing changes of disease status. In conclusion, combined consideration of the distribution characteristics of neutrophil subgroups could help evaluate the diagnosis and prognosis of NSCLC.Graphical abstract• An evaluation system based on OER was developed to assess the specificity of neutrophil subgroups• Specificity of Neu_ c1_ IL1B, Neu_ c2_ cxcr4 (low) and IL-7R + neutrophils changed significantly between preoperative and postoperative blood• 7 gene panels were high specific in all the four NSCLC-associated samples, meaning a high degree of confidence in assessing changes of these subgroups in various disease status

Metabolic alterations of peripheral blood immune cells and heterogeneity of neutrophil in intracranial aneurysms patients.

Intracranial aneurysms (IAs) represent a severe cerebrovascular disease that can potentially lead to subarachnoid haemorrhage. Previous studies have demonstrated the involvement of peripheral immune cells in the formation and progression of IAs. Nevertheless, the impact of metabolic alterations in peripheral immune cells and changes in neutrophil heterogeneity on the occurrence and progression of IAs remains uncertain. Single-cell Cytometry by Time-of-Flight (CyTOF) technology was employed to profile the single-cell atlas of peripheral blood mononuclear cells (PBMCs) and polymorphonuclear cells (PMNs) in 72 patients with IAs. In a matched cohort, metabolic shifts in PBMC subsets of IA patients were investigated by contrasting the expression levels of key metabolic enzymes with their respective counterparts in the healthy control group. Simultaneously, compositional differences in peripheral blood PMNs subsets between the two groups were analysed to explore the impact of altered heterogeneity in neutrophils on the initiation and progression of IAs. Furthermore, integrating immune features based on CyTOF analysis and clinical characteristics, we constructed an aneurysm occurrence model and an aneurysm growth model using the random forest method in conjunction with LASSO regression. Different subsets exhibited distinct metabolic characteristics. Overall, PBMCs from patients elevated CD98 expression and increased proliferation. Conversely, CD36 was up-regulated in T cells, B cells and monocytes from the controls but down-regulated in NK and NKT cells. The comparison also revealed differences in the metabolism and function of specific subsets between the two groups. In terms of PMNs, the neutrophil landscape within patients group revealed a pronounced shift towards heightened complexity. Various neutrophil subsets from the IA group generally exhibited lower expression levels of anti-inflammatory functional molecules (IL-4 and IL-10). By integrating clinical and immune features, the constructed aneurysm occurrence model could precisely identify patients with IAs with high prediction accuracy (AUC=0.987). Furthermore, the aneurysm growth model also exhibited superiority over ELAPSS scores in predicting aneurysm growth (lower prediction errors and out-of-bag errors). These findings enhanced our understanding of peripheral immune cell participation in aneurysm formation and growth from the perspectives of immune metabolism and neutrophil heterogeneity. Moreover, the predictive model based on CyTOF features holds the potential to aid in diagnosing and monitoring the progression of human IAs.

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) deletion in myeloid cells augments cholestatic liver injury

Ductular reactive (DR) cells exacerbate cholestatic liver injury and fibrosis. Herein, we posit that tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) emanates from recruited macrophages and restrains DR cell expansion, thereby limiting cholestatic liver injury. Wild type (WT), Trailfl/fl and myeloid-specific Trail deleted (TrailΔmye) C57BL/6 mice were exposed to DDC diet-induced cholestatic liver injury, which induced hepatomegaly and liver injury as compared to control diet-fed mice. However, parameters of liver injury, fibrosis, and inflammation were all increased in the TrailΔmye mice as compared to the WT and Trailfl/fl mice. High dimensional mass cytometry indicated that cholestasis resulted in increased hepatic recruitment of subsets of macrophages and neutrophils in the TrailΔmye mice. Spatial transcriptomics analysis revealed that the PanCK+ cholangiocytes from TrailΔmye mice had increased expression of the known myeloid attractants S100a8, Cxcl5, Cx3cl1, and Cxcl1. Additionally, in situ hybridization of Cxcl1, a potent neutrophil chemoattractant, demonstrated an increased expression in CK19+ cholangiocytes of TrailΔmye mice. Collectively, these data suggest that TRAIL from myeloid cells, particularly macrophages, restrains a subset of DR cells (i.e., Cxcl1 positive cells), limiting liver inflammation and fibrosis. Reprogramming macrophages to express TRAIL may be salutary in cholestasis.

Blood neutrophil subset predicts the success of immune checkpoint inhibitors in cancer.

Blood neutrophil subset predicts the success of immune checkpoint inhibitors in cancer.

OMIP-100: A flow cytometry panel to investigate human neutrophil subsets.

This 14-color, 13-antibody optimized multicolor immunofluorescence panel (OMIP) was designed for deep profiling of neutrophil subsets in various types of human samples to contextualize neutrophil plasticity in a range of healthy and diseased states. Markers present in the OMIP allow the profiling of neutrophil subsets associated with ontogeny, migration, phagocytosis capacity, granule release, and immune modulation. For panel design, we ensured that the commonly available fluorophores FITC/AF488, PE, and APC were assigned to the intracellular subset marker Olfactomedin 4, the maturity and activation marker CD10, and whole blood subset marker CD177, respectively. These markers can be easily replaced without affecting the core identification of neutrophils, enabling antibodies to new neutrophil antigens of interest or for fluorescent substrates to assess different neutrophil functions to be easily explored. Panel optimization was performed on whole blood and purified neutrophils. We demonstrate applications on clinical samples (whole blood and saliva) and experimental endpoints (purified neutrophils stimulated through an in vitro transmigration assay). We hope that providing a uniform platform to analyze neutrophil plasticity in various sample types will facilitate the future understanding of neutrophil subsets in health and disease.

Detailed phenotyping reveals diverse and highly skewed neutrophil subsets in both the blood and airways during active tuberculosis infection.

Neutrophils play a complex and important role in the immunopathology of TB. Data suggest they are protective during early infection but become a main driver of immunopathology if infection progresses to active disease. Neutrophils are now recognized to exist in functionally diverse states, but little work has been done on how neutrophil states or subsets are skewed in TB disease. To address this, we carried out comprehensive phenotyping by flow cytometry of neutrophils in the blood and airways of individuals with active pulmonary TB with and without HIV co-infection recruited in Durban, South Africa. Active TB was associated with a profound skewing of neutrophils in the blood toward phenotypes associated with activation and apoptosis, reduced phagocytosis, reverse transmigration, and immune regulation. This skewing was also apparently in airway neutrophils, particularly the regulatory subsets expressing PDL-1 and LOX-1. HIV co-infection did not impact neutrophil subsets in the blood but was associated with a phenotypic change in the airways and a reduction in key neutrophil functional proteins cathelicidin and arginase 1. Active TB is associated with profound skewing of blood and airway neutrophils and suggests multiple mechanisms by which neutrophils may exacerbate the immunopathology of TB. These data indicate potential avenues for reducing neutrophil-mediated lung pathology at the point of diagnosis.

Potential Association of Maker Expression of Low-Density Neutrophils and Their Phenotypes in Patients with Periodontitis: Control Study.

Neutrophils play an important role in maintaining periodontal status in conditions of healthy homeostasis. They achieve their surveillance function by continuously migrating to the gingival sulcus and eradicating periodontal pathogens. In addition, neutrophils are considered an integral element in the pathogenesis of periodontal diseases. Among several neutrophil subsets, low-density neutrophils (LDN) have recently received attention and are linked with cancer, immunological, inflammatory, and infectious diseases. However, the presence, phenotypes, and potential role of LDN in the pathogenesis of periodontitis have not yet been investigated. To investigate the presence, subsets (normal, band, suppressive, and active), and phenotypes via marker expression surface protein known as the cluster of differentiation (CD) (CD16b, CD14, CD15, and CD62L) of LDN in patients with periodontitis. The observational case-control study was conducted to estimate the potential role of LDNs in periodontitis. Venous blood and periodontal indices were obtained from 40 healthy control individuals and 60 periodontitis patients. Subsequently, CD16b, CD62L, CD14, and CD15 expression on the surface of LDN was examined by multicolor flow cytometry, and their subsets were classified as "normal" (CD16brightCD62Lbright), "bands" (CD16dimCD62Lbright), "suppressive" (CD16brightCD62Ldim), and "active" (CD16brightCD62Lnegative). There was a significant difference in the expression of LDN markers for active and suppressive phenotypes, respectively, favoring periodontitis over the control group. In contrast, there were significantly higher levels of CD16b, CD62L, and CD15 ("normal") in the control group when compared with the periodontitis group. LDN was associated with periodontitis as it was significantly increased in the periodontitis group in comparison with the control group and was positively correlated with all periodontal parameters. Cells from both groups of patients (periodontitis and control) expressed a normal mature phenotype (CD16b + High, CD62L + High, CD15+, and CD14-). Regarding subsets, the normal LDN (CD16brightCD62Lbright) was the most predominant phenotype in both periodontitis and control groups. However, the active subset increased in periodontitis compared to normal, indicating their destructive role in periodontitis.

Siglec-F+ neutrophils in the spleen induce immunosuppression following acute infection.

Background: The mechanisms underlying the increased mortality of secondary infections during the immunosuppressive phase of sepsis remain elusive. Objectives: We sought to investigate the role of Siglec-F+ neutrophils on splenic T lymphocytes in the immunosuppressed phase of sepsis and on secondary infection in PICS mice, and to elucidate the underlying mechanisms. Methods: We established a mouse model of sepsis-induced immunosuppression followed by secondary infection with LPS or E. coli. The main manifestation of immunosuppression is the functional exhaustion of splenic T lymphocytes. Treg depletion reagent Anti-IL-2, IL-10 blocker Anti-IL-10R, macrophage depletion reagent Liposomes, neutrophil depletion reagent Anti-Ly6G, neutrophil migration inhibitor SB225002, Siglec-F depletion reagent Anti-Siglec-F are all used on PICS mice. The function of neutrophil subsets was investigated by adoptive transplantation and the experiments in vitro. Results: Compared to other organs, we observed a significant reduction in pro-inflammatory cytokines in the spleen, accompanied by a marked increase in IL-10 production, primarily by infiltrating neutrophils. These infiltrating neutrophils in the spleen during the immunosuppressive phase of sepsis undergo phenotypic change in the local microenvironment, exhibiting high expression of neutrophil biomarkers such as Siglec-F, Ly6G, and Siglec-E. Depletion of neutrophils or specifically targeting Siglec-F leads to enhance the function of T lymphocytes and a notable improvement in the survival of mice with secondary infections. Conclusions: We identified Siglec-F+ neutrophils as the primary producers of IL-10, which significantly contributed to T lymphocyte suppression represents a novel finding with potential therapeutic implications.

Unveiling Differential Responses of Granulocytes to Distinct Immunostimulants with Implications in Autoimmune Uveitis.

The perception of circulating granulocytes as cells with a predetermined immune response mainly triggered by pathogens is evolving, recognizing their functional heterogeneity and adaptability, particularly within the neutrophil subset. The involvement of these cells in the pathophysiology of autoimmune uveitis has become increasingly clear, yet their exact role remains elusive. We used an equine model for autoimmune-mediated recurrent pan-uveitis to investigate early responses of granulocytes in different inflammatory environments. For this purpose, we performed differential proteomics on granulocytes from healthy and diseased horses stimulated with IL8, LPS, or PMA. Compared to healthy horses, granulocytes from the recurrent uveitis model significantly changed the cellular abundance of 384 proteins, with a considerable number of specific changes for each stimulant. To gain more insight into the functional impact of these stimulant-specific proteome changes in ERU pathogenesis, we used Ingenuity Pathway Analysis for pathway enrichment. This resulted in specific reaction patterns for each stimulant, with IL8 predominantly promoting Class I MHC-mediated antigen processing and presentation, LPS enhancing processes in phospholipid biosynthesis, and PMA, clearly inducing neutrophil degranulation. These findings shed light on the remarkably differentiated responses of neutrophils, offering valuable insights into their functional heterogeneity in a T-cell-driven disease. Raw data are available via ProteomeXchange with identifier PXD013648.

Single Cell Multi-Omic Analysis of Tumor Microenvironment Evolution across the Disease Spectrum of Multiple Myeloma Identifies Differential Mechanisms of Immune Suppression

Background: Multiple myeloma (MM) is preceded by the precursor states of monoclonal gammopathy of undetermined significance (MGUS) and smoldering multiple myeloma (SMM). The transformation of these precursors into myeloma is influenced not only by the evolution of tumor itself but also by the tumor microenvironment (TME). However, the specific molecular mechanisms and factors within the TME that drive this malignant progression remain largely unknown. Therefore, exploring the TME from non-malignant precursor stages to active myeloma could facilitate the development of novel therapeutic strategies aimed at slowing down this progression and possibly eradicating MM. Methods: We performed paired scRNA-seq, scTCR-seq and scBCR-seq on 148 freshly collected BM aspirate samplesincluding 73 relapsed refractory (RR) RRMM, 16 newly diagnosed (ND) MM, 34 SMM, 21 MGUS and 4 normal BM (nBM) samples. BM aspirates were subjected to CD138+ selection (n=19) or processed as whole BM (WBM) (n=129, among which 73 samples were also enriched for CD138+ cells). cDNA libraries were prepared from enriched CD138+ (n=92) and WBM samples (n=129) followed by simultaneous 5' gene expression (scRNA-seq) and T/B cell receptor sequencing (scTCR/BCR-seq). Single-cell data was processed as previously described (Dang et. al, Cancer Cell, 2023). Results: We profiled 656,371 high-quality cells including 344,665 CD138+ and 311,706 TME cells. We also obtained scTCR-seq and scBCR-seq data on 86,244 and 566,155 cells, respectively. Among them, 394,187 out of 652,399 cells had paired scRNA-seq data. Unsupervised clustering analysis revealed 15 different major TME cell types. Sub-clustering of each major cell type further resolved them into different subsets, resulting in a total of 94 TME cell subsets ( Figure). Overall, we observed a decreased proportion of CD4 T cells, B cells and progenitors and the enrichment of CD8 T cells, monocytes, and neutrophils along the nBM-MGUS-SMM-NDMM-RRMM axis. Notably, the most profound changes were identified within the context of RRMM. In lymphoid cells, we observed a stepwise decrease in mature B cells during disease progression. For T and NK cells, the naïve-like subsets were more abundant in normal bone marrow and the precursors. In contrast, the effector/cytotoxic subsets were enriched in symptomatic MM (NDMM and RRMM). Immunoregulatory T cells, including CD4T_C2 (Treg), CD4T_C4 (Th17) and CD4T_C7 (Tfh), showed an increased proportion within CD4 T cells in MM, particularly in RRMM compared with precursors. Furthermore, we identified a small exhaustion-like CD8 T cell subset which were enriched in RRMM. In myeloid cells, the classical monocytes showed a high degree of transcriptional homogeneity while the non-classical and intermediate monocytes were more heterogeneous. We observed a unique CD16_Mono_C0 subset which downregulated a considerable number of cytokine/chemokine receptors, almost exclusively unique to MM. The macrophage subsets displaying high phagocytosis signature (Macro_C0/3) were enriched in precursors. The monocyte-like macrophages (Macro_C1/2/4), which showed an angiogenesis phenotype, showed greater abundance in RRMM. Neutrophils were found exclusively in symptomatic MM, demonstrating elevated expression levels of TGFB1. Among the neutrophil subsets, those expressing myeloid checkpoints such as PILRA, SIRPA, and VSIR (Neutro_C0/3/4) exhibited increased prevalence in RRMM. In contrast, subsets expressing ARG1 and MMP9 (Neutro_C1/2) were more enriched in NDMM. Within the dendritic cell population, a specific subset characterized by high TGFB1 and VEGFA expression (cDC2_C1) was exclusively present in MM. Additionally, we observed an enriched proliferative dendritic cell subset in MM. Conclusions: We observed a notable pattern of cellular changes along the nBM-MGUS-SMM-NDMM-RRMM axis, indicating a progressive increase in immune suppression primarily driven by myeloid cells. These observations provide valuable insights into immune cell dynamics, their functional characteristics, and potential roles during disease progression and highlight potential targets for further investigation, especially in the context of RRMM.

The Effects of IL-23/IL-18-Polarized Neutrophils on Renal Ischemia-Reperfusion Injury and Allogeneic-Skin-Graft Rejection in Mice.

Neutrophils display heterogeneity and plasticity with different subgroups and immune-regulatory functions under various surrounding conditions. Neutrophils induced by IL-23/IL-18 (referred to N(IL-23+IL-18) neutrophils) have a unique gene-expression profile, with highly expressing IL-17, MHC-II, and costimulatory molecules. The adoptive transfer of N(IL-23+IL-18) neutrophils significantly increased the pathogenesis in a renal ischemia-reperfusion injury mouse model. N(IL-23+IL-18) neutrophils directly and efficiently induced allogeneic T cell proliferation in vitro. N(IL-23+IL-18) neutrophils enhanced the syngeneic T cell response to allogeneic antigens in mixed-lymphocyte reaction assays. The adoptive transfer of the donor or host N(IL-23+IL-18) neutrophils significantly enhanced the antidonor antibody production in an allogeneic-skin-transplanted mouse model, accompanied by increased Tfh cells in the spleens. Therefore, the neutrophil subset induced by IL-23/IL-18 promotes tissue injury and antidonor humoral response in the allogeneic transplantation mouse model.

Isolation methods determine human neutrophil responses after stimulation.

Studying neutrophils is challenging due to their limited lifespan, inability to proliferate, and resistance to genetic manipulation. Neutrophils can sense various cues, making them susceptible to activation by blood collection techniques, storage conditions, RBC lysis, and the isolation procedure itself. Here we assessed the impact of the five most used methods for neutrophil isolation on neutrophil yield, purity, activation status and responsiveness. We monitored surface markers, reactive oxygen species production, and DNA release as a surrogate for neutrophil extracellular trap (NET) formation. Our results show that neutrophils isolated by negative immunomagnetic selection and density gradient methods, without RBC lysis, resembled untouched neutrophils in whole blood. They were also less activated and more responsive to milder stimuli in functional assays compared to neutrophils obtained using density gradients requiring RBC lysis. Our study highlights the importance of selecting the appropriate method for studying neutrophils, and underscores the need for standardizing isolation protocols to facilitate neutrophil subset characterization and inter-study comparisons.

Comparative analysis of peripheral blood immunoinflammatory landscapes in patients with acute cholangitis and its secondary septic shock using single-cell RNA sequencing

BackgroundAcute cholangitis (AC) is a key pathogeny of septic shock, which has a high mortality rate. AC has significant clinical heterogeneity, but no study has analyzed the discrepancies in immunoresponsiveness between AC and its secondary septic shock. The immune inflammatory responses play a critical role in the development of septic shock. MethodsWe performed single-cell RNA sequencing (scRNA-seq) to analyze the differences of immunocytes in immunoresponse and inflammation between the early stages of AC (A1, A2, and A3) and its secondary septic shock (B1, B2, and B3). ResultsThis study has identified seven cell types, including T cells, B cells, plasma cells, neutrophils, monocytes, platelets and erythrocytes. We mainly focused on neutrophils, monocytes, and T cells. Neutrophil subpopulation analysis indicated that neutrophil progenitors (proNeus) were identified in neutrophil subsets. Compared with patients suffering from AC, the gene phenotypes of proNeus (ELANE, AZU1, MPO, and PRTN3) were significantly upregulated in septic shock. The differentiation direction of neutrophil subsets in peripheral blood mononuclear cells (PBMCs) was determined; Moreover, the proNeus in septic shock presented a state of “expansion”, with upregulation of neutrophil degranulation and downregulation of monocyte and T cell proliferation. Neutrophils-7 (CCL5, RPL23A, RPL13, RPS19 and RPS18) were mainly involved in the regulation of cellular functions. The neutrophils-7 subpopulation in septic shock were in a state of “exhaustion”, and its biological functions showed the characteristics of weakening neutrophil migration and phagocytosis, etc., which maked infection difficult to control and aggravated the development of septic shock. Analysis of monocyte and T cell subpopulations showed that the expression genes and biological functions of subpopulations were closely related to immunoinflammatory regulation. In addition, CCL3 - CCR1, CXCL1 - CXCR2 and other ligand-receptors were highly expressed in neutrophils and monocytes, enhancing interactions between immune cells. ConclusionScRNA-seq revealed significant differences in immune cells between AC and its secondary septic shock, which were primarily manifested in the cellular numbers, differentially expressed genes, functions of cellular subsets, differentiation trajectories, cell-cell interactions and so on. We identified many subsets of neutrophil, T cell and monocyte were associated with inflammation and immunosuppression induced by septic shock. These provided a reference for accurately evaluating the pathological severity of patients with AC and discovering the targets for therapy.