Isolation methods determine human neutrophil responses after stimulation

Smart materials in pharmacological drug development: Neutrophils and its constituents for drug delivery and consequent antitumor effects

Neutrophil-based drug delivery systems for targeted therapy of cancer have been studied widely in the recent past. Chemotactic cytokines including colony-stimulating factors (CSFs) recruit various immune cells including the neutrophils to the tumor microenvironment (TME) leading to enhanced metastasis. These cytokines can be targeted effectively by immunotherapeutic agents such as checkpoint inhibitors and mAbs that can lead to systemic toxicity. To minimize the systemic adverse effects, camouflaged nanoparticles can be used significantly as alternative therapeutic agents. The neutrophil-interacting NPs and neutrophil membrane coated NPs have been exploited recently for their antitumor properties in vitro and pose limited systemic adverse effects in vivo. Neutrophil-derived exosomes derived from immune cells can efficiently escape immune-surveillance and pass through the blood-brain barrier. They possess several intrinsic properties in drug delivery as they are nano-sized, extremely biocompatible, non-immunogenic, biodegradable, stable and can carry targeting agents with limited toxicity and display antitumor properties. Also, neutrophil-based nanotherapy is dependent on factors such as neutrophil kinetics and the physicochemical properties of NPs such as size, shape, and surface chemistry. Therefore, neutrophil-based drug delivery for cancer therapy via the use of polymer nanoparticles is widely studied as their clinical appliance in nanomedicine is still at its infancy.

Blood cell separation with magnetic techniques: a critical review

Blood cell separation is a critical process for many clinical and research applications. Among the various techniques employed for blood cell isolation, magnetic techniques are very attractive due to their multiple benefits, i.e. high efficiency, simplicity, low-cost, and no need for expensive equipment or trained operators. Microfluidic devices integrating magnetophoresis have demonstrated promising results for high-throughput separation, with some achieving separation rates of over 108 cells per hour. However, there are many different approaches that can be used for blood magnetic separations, with the selection depending on the sample properties, target cells and purpose of the isolated fractions. This critical review examines recent advances (2014-2025) in magnetic techniques for separating blood cells. Both labeled and label-free approaches are analyzed, with a focus on their performance and impact on cellular function, highlighting their strengths, limitations, and potential for future development in clinical research applications. Among the labeled approaches, positive selection methods have been shown to achieve high purities for various cell types; nevertheless, these techniques might affect cell functionality after separation. Therefore, negative selection can be used for the separation of cells when cellular functionality needs to be preserved. Moreover, label-free techniques, primarily focused on red blood cells (RBCs) separation, can be used for blood cell isolation by leveraging the cells' intrinsic magnetic properties. These methods showed potential for continuous, high-purity RBCs separation, with some devices achieving over 95% recovery and purity. This work aims to provide valuable guidelines for the appropriate selection of magnetic technologies for blood separations to accomplish the successful implementation of magnetophoresis in clinical practice.

No-lyse no-wash flow cytometry method for ex vivo study of human neutrophils

Neutrophils are vital immune cells involved in immunity via their effector roles and death. While their rapid response to the environment is crucial for immune function, it also makes them difficult to study. Here, we provide a no-lyse no-wash (NLNW) flow cytometry protocol to quantify neutrophil viability and death in whole blood with minimal sample handling. Viability of neutrophils was measured by Annexin V/7AAD staining in whole blood at 0 and 20 h. Associated cost, sample volume, and neutrophil survival were compared with traditional density-gradient isolated neutrophils. The NLNW analysis of whole blood immediately after collection showed ∼85% viable neutrophils. After 20 h of incubation, viability dropped to ∼70%, yet was significantly greater compared with isolated neutrophils, where half the population (∼44%) entered early-stage apoptosis. The NLNW flow cytometry method is an efficient and cost-effective method to measure neutrophil viability in small volumes of whole blood with minimal sample handling.

Deep phenotyping of human neutrophils in whole blood using a 33-color spectral flow cytometry panel

Neutrophils are the most abundant leukocytes in the circulation and critical players in host defense and inflammation. They respond rapidly to numerous biological, chemical, and physical stimuli, making it challenging to characterize their steady-state phenotypes, activation states, and subsets in an unbiased and precise manner. To address this problem, we designed a 33-color spectral flow cytometry panel for the deep profiling of unprocessed neutrophils in human blood. This panel allows the profiling of neutrophil phenotypes related to activation, immune modulation, granule release, ontogeny, phagocytic capacity, and migration, in addition to monitoring all major human leukocyte populations. We validated the panel using whole blood stimulations that induce distinct phenotypic shifts in the neutrophil population. This optimized spectral flow cytometry panel allows comprehensive immune profiling of the functional heterogeneity of human blood neutrophils and is suitable for longitudinal or exploratory analysis of neutrophil dynamics and activation states in clinical cohorts.

Chromatin changes associated with neutrophil extracellular trap formation in whole blood reflect complex immune signaling

Background

Neutrophils are key players in innate immunity, forming neutrophil extracellular traps (NETs) to defend against infections. However, excess NET formation is implicated in inflammatory conditions such as sepsis and immunothrombosis. Studying NET formation in isolated neutrophils provides important mechanistic insights but does not reflect the complexity of immune interactions in whole blood, limiting our understanding of neutrophil responses.

Methods

This study investigates chromatin accessibility changes using Assay for Transposase-Accessible Chromatin with sequencing (ATAC-Seq) during phorbol 12-myristate 13-acetate (PMA) induced NET formation in whole blood. We compared chromatin accessibility patterns in neutrophils following PMA treatment in isolation and whole blood to assess the impact of other immune cells and signaling environment.

Results

Whole blood PMA stimulation elicited consistent chromatin accessibility changes across donors, demonstrating organized chromatin decondensation during NET formation. The chromatin response was characterized by increased accessibility in genomic regions enriched for immune-specific pathways, highlighting the role of immune cell interactions in NET formation. Differentially accessible regions (DARs) present following PMA induction in whole blood and isolated neutrophils showed greater association with NET-related and inflammatory transcription factors, while DARs specific to isolated neutrophils showed fewer relevant motifs. Pathway analysis indicated that whole blood responses involved more robust activation of immune-specific pathways, such as interleukin and cytokine signaling, compared to isolated neutrophils.

Conclusions

Our findings underscore the importance of studying NET formation within a whole blood environment to capture the complexity of neutrophil responses and immune cell interactions. This understanding is crucial for identifying effective therapeutic targets in NET-associated inflammatory diseases.

Aberrant expansion of CD177+ neutrophils promotes endothelial dysfunction in systemic lupus erythematosus via neutrophil extracellular traps

OBJECTIVE

Aberrant neutrophil activation is implicated in the pathogenesis of systemic lupus erythematosus (SLE) and its related comorbidities. We found that CD177 was one of the most highly up-regulated genes at the transcriptional level in purified neutrophils from SLE patients. In this study, we aimed to explore the role of CD177+ neutrophils in the pathogenesis of SLE.

METHODS

Expression of CD177 was analyzed by neutrophil transcriptome and flow cytometry. CD177+ neutrophils and CD177-neutrophils were isolated to determine the role of neutrophils-derived NETs in endothelium dysfunction. Wild type and CD177-/- murine model of lupus were analyzed for organ involvement, endothelium-dependent vasorelaxation, serum autoantibodies, and innate and adaptive immune responses in an imiquimod (IMQ)-induced lupus model.

RESULTS

CD177MFI-hi neutrophils and CD177MFI-hi low-density granulocytes (LDGs) were expanded in active SLE, which were weakly but significantly associated with disease activity. CD177+neutrophils displayed enhanced production of reactive oxygen species (ROS) and NETs, which impaired the murine aortic endothelium-dependent vasorelaxation and induced endothelial cell apoptosis. Moreover, CD177-/- mice exposed to IMQ showed alleviated splenomegaly, endothelium-dependent vasorelaxation, and renal immune complex deposition.

CONCLUSIONS

Our findings indicated that CD177 MFI-hi may serve as a novel biomarker for monitoring disease activity in SLE. Further, CD177+ neutrophils may play a vasculopathic role in cardiovascular disease (CVD) via NETs formation, suggesting that specific targeting CD177+ neutrophil subset may have therapeutic effect in SLE but reducing the levels of NETs-prone neutrophils.

"The NET effect": Neutrophil extracellular traps-a potential key component of the dysregulated host immune response in sepsis

Neutrophils release neutrophil extracellular traps (NETs) as part of a healthy host immune response. NETs physically trap and kill pathogens as well as activating and facilitating crosstalk between immune cells and complement. Excessive or inadequately resolved NETs are implicated in the underlying pathophysiology of sepsis and other inflammatory diseases, including amplification of the inflammatory response and inducing thrombotic complications. Here, we review the growing evidence implicating neutrophils and NETs as central players in the dysregulated host immune response. We discuss potential strategies for modifying NETs to improve patient outcomes and the need for careful patient selection.

A Point-of-Care Diagnostic Platform for Detecting Host Immune Activation due to Infections: Cytocapture of Biomarkers In Situ (CyBIS)

The prompt diagnosis of internal infections is an important, but surprisingly difficult, component of healthcare. Existing clinical and laboratory tests, such as complete blood counts, are low accuracy (~70%), time consuming (>90 min), and require expensive blood analyzers. More sensitive and specific tests, such as PCR or sequencing, require access to a sample of the infected tissue, genomic data for all potential pathogens and expensive equipment. Culturing organisms introduces its own biases and is prone to false positives due to contamination. We describe a device for the rapid isolation of neutrophils and measurement of neutrophil elastase activity to provide a measure of host immune activity toward a broad range of infectious agents. CyBIS (Cytocapture of Biomarkers In Situ) is a Point-of-Care (POC) device that isolates neutrophils from a small volume of blood (75 ul) using anti-CD66b antibody-coated paramagnetic beads and analyzes elastase activity via a kinetic assay. This inexpensive and rapid (35 min) testing system provides a quantitative measure that combines neutrophil count with neutrophil elastase activity per cell to diagnose elevated host immune activity and possible infection. Neutrophil-associated elastase is elevated in emergency department patients with clinically relevant infections, including sepsis, compared to healthy control patients.

Polyethylene Glycols Stimulate Ca2+ Signaling, Cytokine Production, and the Formation of Neutrophil Extracellular Traps

Purpose

Given the increased use of polyethylene glycol (PEG) in refining the therapeutic activity of medicines, our research focuses on explaining the potential mechanism of immune reactions associated with this polymer. We aim to investigate the interaction of different types of PEG with mouse and human immune cells, thereby contributing to understanding PEG interactions with the immune system and verifying the proinflammatory activity of the tested polymers.

Patients and Methods

Mouse macrophage and neutrophil cell lines, human peripheral blood mononuclear cells, and polymorphonuclear cells isolated from healthy donors were exposed to various PEGs. ROS, NO, and cytokine production were analyzed using fluorescence intensity, absorbance, or cytometric measurements. Toll-like receptor (TLR) signaling was verified using HEK-blue-reporter cell lines. Finally, neutrophil trap formation was studied using immunofluorescence labeling, and calcium imaging was performed using a Ca2+-sensitive indicator and fluorescence microscope.

Results

Our findings show that specific PEG and mPEG are not toxic to tested mouse and human cells. However, they exert proinflammatory activity against human immune cells, as evidenced by the increased secretion of proinflammatory cytokines, such as IFN-a2, IFN-γ, TNF-α, MCP-1, IL-8, IL-17A, and IL-23. This phenomenon is independent of PEG signaling via TLR. Additionally, mPEG10 induced the formation of neutrophil extracellular traps and intracellular calcium signaling.

Conclusion

Our finding suggests that some PEG types have proinflammatory activity against human immune cells, manifesting in the upregulated production of cytokines and neutrophils trap releasing.

Fc receptors are key discriminatory markers of granulocytes subsets in people living with HIV-1

Introduction

Granulocytes are innate immune cells that play a key role in pathogen elimination. Recent studies revealed the diversity of granulocytes in terms of phenotype and function. In particular, a subset of granulocytes identified as low-density granulocytes (LDG) has been described in physiological conditions and with increased frequencies in several pathological contexts. However, the properties of LDG are still controversial as they vary according to the pathophysiological environment. Here we investigated the heterogeneity of granulocyte populations and the potential differences in phenotype and immunomodulatory capacity between LDG and normal density granulocytes (NDG) in people living with HIV-1 (PLWH).

Methods

To this end, we developed an optimized method to purify LDG and NDG from a single blood sample, and performed in-depth, comparative phenotypic characterization of both granulocyte subtypes. We also assessed the impact of purification steps on the expression of cell surface markers on LDG by immunophenotyping them at different stages of isolation.

Results

We identified 9 cell surface markers (CD16, CD32, CD89, CD62L, CD177, CD31, CD10, CXCR4 and CD172α) differentially expressed between LDG and NDG. Noteworthy, markers that distinguish the two subsets include receptors for the Fc part of IgG (CD16, CD32) and IgA (CD89). Importantly, we also highlighted that the purification procedure affects the expression of several cell surface markers (i.e.CD63, CD66b, …) which must be taken into account when characterizing LDG. Our work sheds new light on the properties of LDG in PLWH and provides an extensive characterization of this granulocyte subset in which Fc receptors are key discriminatory markers.