Albumin Nanoparticle Endocytosing Subset of Neutrophils for Precision Therapeutic Targeting of Inflammatory Tissue Injury

Nanotechnology-Mediated Immunomodulation Strategy for Inflammation Resolution

Inflammation serves as a common characteristic across a wide range of diseases and plays a vital role in maintaining homeostasis. Inflammation can lead to tissue damage and the onset of inflammatory diseases. Although significant progress is made in anti-inflammation in recent years, the current clinical approaches mainly rely on the systemic administration of corticosteroids and antibiotics, which only provide short-term relief. Recently, immunomodulatory approaches have emerged as promising strategies for facilitating the resolution of inflammation. Especially, the advanced nanosystems with unique biocompatibility and multifunctionality have provided an ideal platform for immunomodulation. In this review, the pathophysiology of inflammation and current therapeutic strategies are summarized. It is mainly focused on the nanomedicines that modulate the inflammatory signaling pathways, inflammatory cells, oxidative stress, and inflammation targeting. Finally, the challenges and opportunities of nanomaterials in addressing inflammation are also discussed. The nanotechnology-mediated immunomodulation will open a new treatment strategy for inflammation therapy.

Marginated Neutrophils in the Lungs Effectively Compete for Nanoparticles Targeted to the Endothelium, Serving as a Part of the Reticuloendothelial System

Nanomedicine has long pursued the goal of targeted delivery to specific organs and cell types but has yet to achieve this goal with the vast majority of targets. One rare example of success in this pursuit has been the 25+ years of studies targeting the lung endothelium using nanoparticles conjugated to antibodies against endothelial surface molecules. However, here we show that such "endothelial-targeted" nanocarriers also effectively target the lungs' numerous marginated neutrophils, which reside in the pulmonary capillaries and patrol for pathogens. We show that marginated neutrophils' uptake of many of these "endothelial-targeted" nanocarriers is on par with endothelial uptake. This generalizes across diverse nanomaterials and targeting moieties and was even found with physicochemical lung tropism (i.e., without targeting moieties). Further, we observed this in ex vivo human lungs and in vivo healthy mice, with an increase in marginated neutrophil uptake of nanoparticles caused by local or distant inflammation. These findings have implications for nanomedicine development for lung diseases. These data also suggest that marginated neutrophils, especially in the lungs, should be considered a major part of the reticuloendothelial system (RES), with a special role in clearing nanoparticles that adhere to the lumenal surfaces of blood vessels.

Albumin Nanoparticle-Based Drug Delivery Systems

Nanoparticle-based systems are extensively investigated for drug delivery. Among others, with superior biocompatibility and enhanced targeting capacity, albumin appears to be a promising carrier for drug delivery. Albumin nanoparticles are highly favored in many disease therapies, as they have the proper chemical groups for modification, cell-binding sites for cell adhesion, and affinity to protein drugs for nanocomplex generation. Herein, this review summarizes the recent fabrication techniques, modification strategies, and application of albumin nanoparticles. We first discuss various albumin nanoparticle fabrication methods, from both pros and cons. Then, we provide a comprehensive introduction to the modification section, including organic albumin nanoparticles, metal albumin nanoparticles, inorganic albumin nanoparticles, and albumin nanoparticle-based hybrids. We finally bring further perspectives on albumin nanoparticles used for various critical diseases.

Nanoparticle-neutrophils interactions for autoimmune regulation

Neutrophils play an essential role as 'first responders' in the immune response, necessitating many immune-modulating capabilities. Chronic, unresolved inflammation is heavily implicated in the progression and tissue-degrading effects of autoimmune disease. Neutrophils modulate disease pathogenesis by interacting with the inflammatory and autoreactive cells through effector functions, including signaling, degranulation, and neutrophil extracellular traps (NETs) release. Since the current gold standard systemic glucocorticoid administration has many drawbacks and side effects, targeting neutrophils in autoimmunity provides a new approach to developing therapeutics. Nanoparticles enable targeting of specific cell types and controlled release of a loaded drug cargo. Thus, leveraging nanoparticle properties and interactions with neutrophils provides an exciting new direction toward novel therapies for autoimmune diseases. Additionally, recent work has utilized neutrophil properties to design novel targeted particles for delivery into previously inaccessible areas. Here, we outline nanoparticle-based strategies to modulate neutrophil activity in autoimmunity, including various nanoparticle formulations and neutrophil-derived targeting.

Physiologically based pharmacokinetic model for predicting the biodistribution of albumin nanoparticles after induction and recovery from acute lung injury

The application of nanomedicine in the treatment of acute lung injury (ALI) has great potential for the development of new therapeutic strategies. To gain insight into the kinetics of nanocarrier distribution upon time-dependent changes in tissue permeability after ALI induction in mice, we developed a physiologically based pharmacokinetic model for albumin nanoparticles (ANP). The model was calibrated using data from mice treated with intraperitoneal LPS (6 mg/kg), followed by intravenous ANP (0.5 mg/mouse or about 20.8 mg/kg) at 0.5, 6, and 24 h. The simulation results reproduced the experimental observations and indicated that the accumulation of ANP in the lungs increased, reaching a peak 6 h after LPS injury, whereas it decreased in the liver, kidney, and spleen. The model predicted that LPS caused an immediate (within the first 30 min) dramatic increase in lung and kidney tissue permeability, whereas splenic tissue permeability gradually increased over 24 h after LPS injection. This information can be used to design new therapies targeting specific organs affected by bacterial infections and potentially by other inflammatory insults.

Combination of Physicochemical Tropism and Affinity Moiety Targeting of Lipid Nanoparticles Enhances Organ Targeting

Two camps have emerged for targeting nanoparticles to specific organs and cell types: affinity moiety targeting and physicochemical tropism. Here we directly compare and combine both using intravenous (IV) lipid nanoparticles (LNPs) designed to target the lungs. We utilized PECAM antibodies as affinity moieties and cationic lipids for physicochemical tropism. These methods yield nearly identical lung uptake, but aPECAM LNPs show higher endothelial specificity. LNPs combining these targeting methods had >2-fold higher lung uptake than either method alone and markedly enhanced epithelial uptake. To determine if lung uptake is because the lungs are the first organ downstream of IV injection, we compared IV vs intra-arterial (IA) injection into the carotid artery, finding that IA combined-targeting LNPs achieve 35% of the injected dose per gram (%ID/g) in the first-pass organ, the brain, among the highest reported. Thus, combining the affinity moiety and physicochemical strategies provides benefits that neither targeting method achieves alone.

Neutrophils exacerbate acetaminophen-induced liver injury by producing cytotoxic interferon-γ

BACKGROUND

Drug (e.g., acetaminophen, APAP)-associated hepatotoxicity is the major cause of acute liver failure. Emerging evidence shows that initial tissue damage caused by APAP triggers molecular and cellular immune responses, which can modulate the severity of hepatoxicity. The pro-inflammatory and cytotoxic cytokine interferon (IFN)-γ has been reported as a key molecule contributing to APAP-induced liver injury (AILI). However, its cellular source remains undetermined.

RESULTS

In the current study, we show that elevation of serum IFN-γ in patients with drug hepatotoxicity correlates with disease severity. Neutralization of IFN-γ in a mouse model of AILI effectively reduces hepatotoxicity. Strikingly, we reveal that IFN-γ is expressed primarily by hepatic neutrophils, not by conventional immune cells with known IFN-γ-producing capability, e.g., CD8+ T cells, CD4+ T cells, natural killer cells, or natural killer T cells. Upon encountering APAP-injured hepatocytes, neutrophils secrete cytotoxic IFN-γ further causing cell stress and damage, which can be abrogated in the presence of blocking antibodies for IFN-γ or IFN-γreceptor. Furthermore, removal of neutrophils in vivo substantially decreases hepatic IFN-γ levels concomitantly with reduced APAP hepatotoxicity, whereas adoptive transfer of IFN-γ-producing neutrophils confers IFN-γ-/- mice susceptibility to APAP administration.

CONCLUSIONS

Our findings uncover a novel mechanism of neutrophil action in promoting AILI and provide new insights into immune modulation of the disease pathogenesis.

Advanced hitchhiking nanomaterials for biomedical applications

Hitchhiking, a recently developed bio-inspired cargo delivery system, has been harnessed for diverse applications. By leveraging the interactions between nanoparticles and circulatory cells or proteins, hitchhiking enables efficient navigation through the vasculature while evading immune system clearance. Moreover, it allows for targeted delivery of nutrients to tissues, surveillance of the immune system, and pathogen elimination. Various synthetic nanomaterials have been developed to facilitate hitchhiking with circulatory cells or proteins. By combining the advantages of synthetic nanomaterials and circulatory cells or proteins, hitchhiking nanomaterials demonstrate several advantages over conventional vectors, including enhanced circulatory stability and optimized therapeutic efficacy. This review provides an overview of general strategies for hitchhiking, choices of cells and proteins, and recent advances of hitchhiking nanomaterials for biomedical applications.

Efferocytosis-inspired nanodrug treats sepsis by alleviating inflammation and secondary immunosuppression

Uncontrolled inflammation storm induced by sepsis may lead to severe organ dysfunction and secondary immunosuppression, which is one of the main reasons for high mortality and prolonged hospitalization of septic patients. However, there is a lack of effective treatments for it at present. Here, we report an efferocytosis-inspired nanodrug (BCN@M) to treat sepsis and secondary immunosuppression via regulating the macrophage function. Bioactive molecular curcumin was loaded with bovine serum albumin and then coated with the damaged erythrocyte membrane derived from septic mice. It was found that the septic erythrocytes promoted the efferocytosis signal and BCN@M uptake efficiency by macrophages. The well-constructed BCN@M nanodrug reduced the hyperinflammation in sepsis and restored the bacterial clearance ability of macrophage in the secondary immunosuppression state. This study highlights BCN@M as an efferocytosis-inspired nanodrug to alleviate hyperinflammation and secondary immunosuppression of sepsis.

The double-edged role of neutrophil heterogeneity in inflammatory diseases and cancers

Neutrophils are important immune cells act as the body's first line of defense against infection and respond to diverse inflammatory cues. Many studies have demonstrated that neutrophils display plasticity in inflammatory diseases and cancers. Clarifying the role of neutrophil heterogeneity in inflammatory diseases and cancers will contribute to the development of novel treatment strategies. In this review, we have presented a review on the development of the understanding on neutrophil heterogeneity from the traditional perspective and a high-resolution viewpoint. A growing body of evidence has confirmed the double-edged role of neutrophils in inflammatory diseases and tumors. This may be due to a lack of precise understanding of the role of specific neutrophil subsets in the disease. Thus, elucidating specific neutrophil subsets involved in diseases would benefit the development of precision medicine. Thusly, we have summarized the relevance and actions of neutrophil heterogeneity in inflammatory diseases and cancers comprehensively. Meanwhile, we also discussed the potential intervention strategy for neutrophils. This review is intended to deepen our understanding of neutrophil heterogeneity in inflammatory diseases and cancers, while hold promise for precise treatment of neutrophil-related diseases.

Targeted Nanocarriers Co-Opting Pulmonary Intravascular Leukocytes for Drug Delivery to the Injured Brain

Ex vivo-loaded white blood cells (WBC) can transfer cargo to pathological foci in the central nervous system (CNS). Here we tested affinity ligand driven in vivo loading of WBC in order to bypass the need for ex vivo WBC manipulation. We used a mouse model of acute brain inflammation caused by local injection of tumor necrosis factor alpha (TNF-α). We intravenously injected nanoparticles targeted to intercellular adhesion molecule 1 (anti-ICAM/NP). We found that (A) at 2 h, >20% of anti-ICAM/NP were localized to the lungs; (B) of the anti-ICAM/NP in the lungs >90% were associated with leukocytes; (C) at 6 and 22 h, anti-ICAM/NP pulmonary uptake decreased; (D) anti-ICAM/NP uptake in brain increased up to 5-fold in this time interval, concomitantly with migration of WBCs into the injured brain. Intravital microscopy confirmed transport of anti-ICAM/NP beyond the blood-brain barrier and flow cytometry demonstrated complete association of NP with WBC in the brain (98%). Dexamethasone-loaded anti-ICAM/liposomes abrogated brain edema in this model and promoted anti-inflammatory M2 polarization of macrophages in the brain. In vivo targeted loading of WBC in the intravascular pool may provide advantages of coopting WBC predisposed to natural rapid mobilization from the lungs to the brain, connected directly via conduit vessels.

Neutrophils and neutrophil extracellular traps in cancer: promising targets for engineered nanomaterials

Neutrophils are the most abundant white blood cells in circulation and constitute up to 60% of circulating leukocytes. Neutrophils play a significant role in host defense against pathogens through various mechanisms, including phagocytosis, production of antimicrobial proteins, and formation of neutrophil extracellular traps (NETs). Recently, the role of neutrophils and NETs in cancer has generated significant interest, as accumulating evidence suggests that neutrophils and NETs contribute to cancer progression and are associated with adverse patient outcomes. In this review, we will first highlight the roles of neutrophils and NETs in cancer progression and metastasis and discuss new drug delivery approaches to target and modulate neutrophils and NETs for cancer therapeutics.

Neutrophil sub-types in maintaining immune homeostasis during steady state, infections and sterile inflammation

INTRODUCTION

Neutrophils are component of innate immune system and a) eliminate pathogens b) maintain immune homeostasis by regulating other immune cells and c) contribute to the resolution of inflammation. Neutrophil mediated inflammation has been described in pathogenesis of various diseases. This indicates neutrophils do not represent homogeneous population but perform multiple functions through confined subsets. Hence, in the present review we summarize various studies describing the heterogeneous nature of neutrophils and associated functions during steady state and pathological conditions.

METHODOLOGY

We performed extensive literature review with key words 'Neutrophil subpopulations' 'Neutrophil subsets', Neutrophil and infections', 'Neutrophil and metabolic disorders', 'Neutrophil heterogeneity' in PUBMED.

RESULTS

Neutrophil subtypes are characterized based on buoyancy, cell surface markers, localization and maturity. Recent advances in high throughput technologies indicate the existence of functionally diverse subsets of neutrophils in bone marrow, blood and tissues in both steady state and pathological conditions. Further, we found proportions of these subsets significantly vary in pathological conditions. Interestingly, stimulus specific activation of signalling pathways in neutrophils have been demonstrated.

CONCLUSION

Neutrophil sub-populations differ among diseases and hence, mechanisms regulating formation, sustenance, proportions and functions of these sub-types vary between physiological and pathological conditions. Hence, mechanistic insights of neutrophil subsets in disease specific manner may facilitate development of neutrophil-targeted therapies.

Strategies of neutrophil diversification

Neutrophils are formidable defenders. Their vast numbers, constant production, high cytotoxicity and capacity to produce extracellular traps, underlie their ability to efficiently protect in a microorganism-rich world. However, neutrophils are much more than immune sentinels, as evidenced by the expanding repertoire of functions discovered in the context of tissue homeostasis, regeneration or chronic pathologies. In this Perspective, we discuss general functional features of the neutrophil compartment that may be relevant in most, if not all, physiological scenarios in which they participate, including specialization in naïve tissues, transcriptional noise in the bloodstream as a potential strategy for diversification and functional bias in inflammatory sites. We intentionally present the reader with more questions than answers and propose models and approaches that we hope will shed new light onto the biology of these fascinating cells and spark new directions of research.

Neutrophils are gatekeepers of mucosal immunity

Mucosal tissues are constantly exposed to the outside environment. They receive signals from the commensal microbiome and tissue-specific triggers including alimentary and airborne elements and are tasked to maintain balance in the absence of inflammation and infection. Here, we present neutrophils as sentinel cells in mucosal immunity. We discuss the roles of neutrophils in mucosal homeostasis and overview clinical susceptibilities in patients with neutrophil defects. Finally, we present concepts related to specification of neutrophil responses within specific mucosal tissue microenvironments.

Regulation of cGAS Activity and Downstream Signaling

Cyclic GMP-AMP synthase (cGAS) is a predominant and ubiquitously expressed cytosolic onfirmedDNA sensor that activates innate immune responses by producing a second messenger, cyclic GMP-AMP (cGAMP), and the stimulator of interferon genes (STING). cGAS contains a highly disordered N-terminus, which can sense genomic/chromatin DNA, while the C terminal of cGAS binds dsDNA liberated from various sources, including mitochondria, pathogens, and dead cells. Furthermore, cGAS cellular localization dictates its response to foreign versus self-DNA. Recent evidence has also highlighted the importance of dsDNA-induced post-translational modifications of cGAS in modulating inflammatory responses. This review summarizes and analyzes cGAS activity regulation based on structure, sub-cellular localization, post-translational mechanisms, and Ca²⁺ signaling. We also discussed the role of cGAS activation in different diseases and clinical outcomes.

Usage of Nanoparticles to Alter Neutrophils' Function for Therapy

Neutrophils, the most abundant white blood cells in the human body, are important immune cells responsible for the innate immune response. Neutrophils can migrate to inflammatory areas, such as tumor sites and infection sites, because of chemotaxis. Neutrophil-based nanomaterials, such as neutrophil-nanomaterial composites and neutrophil membrane-based nanomaterials, can help the drug or imaging agent gather in the inflammatory area with the help of chemotaxis. In addition, some nanomaterials can interfere with the function of neutrophils to treat tissue damage caused by excessive local accumulation of neutrophils. This review focuses on the interaction between nanomaterials and neutrophils as well as the applications of neutrophil-based nanomaterials and neutrophil-interfering nanomaterials.