NLRP3 inflammasome activation induced by engineered nanomaterials

Therapeutic role of inflammasome inhibitors in neurodegenerative disorders

Neuroinflammation, characterized by the activation of glial cells, is a hallmark in several neurological and neurodegenerative disorders. Inadequate inflammation cannot eliminate the infection of pathogens, while excessive or hyper-reactive inflammation can cause chronic or systemic inflammatory diseases affecting the central nervous system (CNS). In response to a brain injury or pathogen invasion, the pathogen recognition receptors (PRRs) expressed on glial cells are activated via binding to cellular damage-associated molecular patterns (DAMPs) or pathogen-associated molecular patterns (PAMPs). This subsequently leads to the activation of NOD (nucleotide-binding oligomerization domain)-like receptor proteins (NLRs). In neurodegenerative diseases such as HIV-1-associated neurocognitive disorders (HAND), Alzheimer's disease (AD), Parkinson's disease (PD), and multiple sclerosis (MS), chronic inflammation is a critical contributing factor for disease manifestation including pathogenesis. Emerging evidence points to the involvement of "inflammasomes", especially the nucleotide-binding oligomerization domain, leucine-rich repeat, and pyrin domain-containing (NLRP) complex in the development of these diseases. The activated NLRP3 results in the proteolytic activation of caspase-1 that facilitates the cleavage of pro-IL-1β and the secretion of IL-1β and IL-18 proinflammatory cytokines. Accordingly, these and other seminal findings have led to the development of NLRP-targeting small-molecule therapeutics as possible treatment options for neurodegenerative disorders. In this review, we will discuss the new advances and evidence-based literature concerning the role of inflammasomes in neurodegenerative diseases, its role in the neurological repercussions of CNS chronic infection, and the examples of preclinical or clinically tested NLRP inhibitors as potential strategies for the treatment of chronic neurological diseases.

Modulation of Macrophages M1/M2 Polarization Using Carbohydrate-Functionalized Polymeric Nanoparticles

Exploiting surface endocytosis receptors using carbohydrate-conjugated nanocarriers brings outstanding approaches to an efficient delivery towards a specific target. Macrophages are cells of innate immunity found throughout the body. Plasticity of macrophages is evidenced by alterations in phenotypic polarization in response to stimuli, and is associated with changes in effector molecules, receptor expression, and cytokine profile. M1-polarized macrophages are involved in pro-inflammatory responses while M2 macrophages are capable of anti-inflammatory response and tissue repair. Modulation of macrophages’ activation state is an effective approach for several disease therapies, mediated by carbohydrate-coated nanocarriers. In this review, polymeric nanocarriers targeting macrophages are described in terms of production methods and conjugation strategies, highlighting the role of mannose receptor in the polarization of macrophages, and targeting approaches for infectious diseases, cancer immunotherapy, and prevention. Translation of this nanomedicine approach still requires further elucidation of the interaction mechanism between nanocarriers and macrophages towards clinical applications.

The role of lysosome in regulated necrosis

Lysosome is a ubiquitous acidic organelle fundamental for the turnover of unwanted cellular molecules, particles, and organelles. Currently, the pivotal role of lysosome in regulating cell death is drawing great attention. Over the past decades, we largely focused on how lysosome influences apoptosis and autophagic cell death. However, extensive studies showed that lysosome is also prerequisite for the execution of regulated necrosis (RN). Different types of RN have been uncovered, among which, necroptosis, ferroptosis, and pyroptosis are under the most intensive investigation. It becomes a hot topic nowadays to target RN as a therapeutic intervention, since it is important in many patho/physiological settings and contributing to numerous diseases. It is promising to target lysosome to control the occurrence of RN thus altering the outcomes of diseases. Therefore, we aim to give an introduction about the common factors influencing lysosomal stability and then summarize the current knowledge on the role of lysosome in the execution of RN, especially in that of necroptosis, ferroptosis, and pyroptosis.

15 Years of Small: Research Trends in Nanosafety

In the field of nano- and microscale science and technology, Small has become one of the worldwide leading journals since its initiation 15 years ago. Among all the topics covered in Small, "nanosafety" has received growing interest over the years, which accounts for a large proportion of the total publications of Small. Herein, inspired by its coming Special Issue "Rethinking Nanosafety," a general bibliometric overview of the nanosafety studies that have been published in Small is presented. Using the data derived from the Web of Science Core Collection, the annual publication growth, most influential countries/institutions as well as the visualized collaborations between different countries and institutions based on CiteSpace software are presented. A special emphasis on the impact of the previous Special Issue from Small that is related to nanosafety research is given and the research trend from the most highly cited papers during last 15 years is analyzed. Lastly, future research directions are also proposed.

Safety Considerations of Cancer Nanomedicine-A Key Step toward Translation

The rate of translational effort of nanomedicine requires strategic planning of nanosafety research in order to enable clinical trials and safe use of nanomedicine in patients. Herein, the experiences that have emerged based on the safety data of classic liposomal formulations in the space of oncology are discussed, along with a description of the new challenges that need to be addressed according to the rapid expansion of nanomedicine platform beyond liposomes. It is valuable to consider the combined use of predictive toxicological assessment supported by deliberate investigation on aspects such as absorption, distribution, metabolism, and excretion (ADME) and toxicokinetic profiles, the risk that may be introduced during nanomanufacture, unique nanomaterials properties, and nonobvious nanosafety endpoints, for example. These efforts will allow the generation of investigational new drug-enabling safety data that can be incorporated into a rational infrastructure for regulatory decision-making. Since the safety assessment relates to nanomaterials, the investigation should cover the important physicochemical properties of the material that may lead to hazards when the nanomedicine product is utilized in humans.

Dexmedetomidine Enhances Autophagy via α2-AR/AMPK/mTOR Pathway to Inhibit the Activation of NLRP3 Inflammasome and Subsequently Alleviates Lipopolysaccharide-Induced Acute Kidney Injury

Background

Acute kidney injury (AKI) is a severe complication of sepsis; however, no effective drugs have been found. Activation of the nucleotide-binding domain-like receptor protein 3 (NLRP3) inflammasome is a major pathogenic mechanism of AKI induced by lipopolysaccharide (LPS). Autophagy, a process of intracellular degradation related to renal homeostasis, effectively restricts inflammatory responses. Herein, we explored the potential protective mechanisms of dexmedetomidine (DEX), which has confirmed anti-inflammatory effects, on LPS-induced AKI.

Methods

AKI was induced in rats by injecting 10 mg/kg of LPS intraperitoneally (i.p.). Wistar rats received intraperitoneal injections of DEX (30 µg/kg) 30 min before an intraperitoneal injection of LPS. Atipamezole (ATI) (250 µg/kg) and 3-methyladenine (3-MA) (15 mg/kg) were intraperitoneally injected 30 min before the DEX injection.

Results

DEX significantly attenuated renal injury. Furthermore, DEX decreased activation of the NLRP3 inflammasome and expression of interleukins 1β and 18. In addition, autophagy-related protein and gene analysis indicated that DEX could significantly enhance autophagy. Finally, we verified the pharmacological effects of DEX on the 5′-adenosine monophosphate-activated protein kinase (AMPK)/mechanistic target of rapamycin (mTOR) pathway. Atip and 3-MA significantly reversed the protective effects of DEX.

Conclusions

Our results suggest that the protective effects of DEX were mediated by enhanced autophagy via the α₂-adrenoreceptor/AMPK/mTOR pathway, which decreased activation of the NLRP3 inflammasome. Above all, we verified the renal protective effects of DEX and offer a new treatment strategy for AKI.

Silica nanoparticles induce lung inflammation in mice via ROS/PARP/TRPM2 signaling-mediated lysosome impairment and autophagy dysfunction

Background

Wide applications of nanoparticles (NPs) have raised increasing concerns about safety to humans. Oxidative stress and inflammation are extensively investigated as mechanisms for NPs-induced toxicity. Autophagy and lysosomal dysfunction are emerging molecular mechanisms. Inhalation is one of the main pathways of exposing humans to NPs, which has been reported to induce severe pulmonary inflammation. However, the underlying mechanisms and, more specifically, the interplays of above-mentioned mechanisms in NPs-induced pulmonary inflammation are still largely obscure. Considered that NPs exposure in modern society is often unavoidable, it is highly desirable to develop effective strategies that could help to prevent nanomaterials-induced pulmonary inflammation.

Results

Pulmonary inflammation induced by intratracheal instillation of silica nanoparticles (SiNPs) in C57BL/6 mice was prevented by PJ34, a poly (ADP-ribose) polymerase (PARP) inhibitor. In human lung bronchial epithelial (BEAS-2B) cells, exposure to SiNPs reduced cell viability, and induced ROS generation, impairment in lysosome function and autophagic flux. Inhibition of ROS generation, PARP and TRPM2 channel suppressed SiNPs-induced lysosome impairment and autophagy dysfunction and consequent inflammatory responses. Consistently, SiNPs-induced pulmonary inflammation was prevented in TRPM2 deficient mice.

Conclusion

The ROS/PARP/TRPM2 signaling is critical in SiNPs-induced pulmonary inflammation, providing novel mechanistic insights into NPs-induced lung injury. Our study identifies TRPM2 channel as a new target for the development of preventive and therapeutic strategies to mitigate nanomaterials-induced lung inflammation.

Graphical abstract

Addressing Nanomaterial Immunosafety by Evaluating Innate Immunity across Living Species

The interaction of a living organism with external foreign agents is a central issue for its survival and adaptation to the environment. Nanosafety should be considered within this perspective, and it should be examined that how different organisms interact with engineered nanomaterials (NM) by either mounting a defensive response or by physiologically adapting to them. Herein, the interaction of NM with one of the major biological systems deputed to recognition of and response to foreign challenges, i.e., the immune system, is specifically addressed. The main focus is innate immunity, the only type of immunity in plants, invertebrates, and lower vertebrates, and that coexists with adaptive immunity in higher vertebrates. Because of their presence in the majority of eukaryotic living organisms, innate immune responses can be viewed in a comparative context. In the majority of cases, the interaction of NM with living organisms results in innate immune reactions that eliminate the possible danger with mechanisms that do not lead to damage. While in some cases such interaction may lead to pathological consequences, in some other cases beneficial effects can be identified.

Continued Efforts on Nanomaterial-Environmental Health and Safety Is Critical to Maintain Sustainable Growth of Nanoindustry

Nanotechnology is enjoying an impressive growth and the global nanotechnology industry is expected to exceed US$ 125 billion by 2024. Based on these successes, there are notions that enough is known and efforts on engineered nanomaterial environmental health and safety (nano-EHS) research should be put on the back burner. However, there are recent events showing that it is not the case. The US Food and Drug Administration found ferumoxytol (carbohydrate-coated superparamagnetic iron oxide nanoparticle) for anemia treatment could induce lethal anaphylactic reactions. The European Union will categorize TiO2 as a category 2 carcinogen due to its inhalation hazard and France banned use of TiO2 (E171) in food from January 1, 2020 because of its carcinogenic potential. Although nanoindustry is seemingly in a healthy state, growth could be hindered for the lack of certainty and more nano-EHS research is needed for the sustainable growth of nanoindustry. Herein, the current knowledge gaps and the way forward are elaborated.

Mechanistic Differences in Cell Death Responses to Metal-Based Engineered Nanomaterials in Kupffer Cells and Hepatocytes

The mononuclear phagocyte system in the liver is a frequent target for nanoparticles (NPs). A toxicological profiling of metal-based NPs is performed in Kupffer cell (KC) and hepatocyte cell lines. Sixteen NPs are provided by the Nanomaterial Health Implications Research Consortium of the National Institute of Environmental Health Sciences to study the toxicological effects in KUP5 (KC) and Hepa 1-6 cells. Five NPs (Ag, CuO, ZnO, SiO2 , and V2 O5 ) exhibit cytotoxicity in both cell types, while SiO2 and V2 O5 induce IL-1β production in KC. Ag, CuO, and ZnO induced caspase 3 generated apoptosis in both cell types is accompanied by ion shedding and generation of mitochondrial reactive oxygen species (ROS) in both cell types. However, the cell death response to SiO2 in KC differs by inducing pyroptosis as a result of potassium efflux, caspase 1 activation, NLRP3 inflammasome assembly, IL-1β release, and cleavage of gasdermin-D. This releases pore-performing peptide fragments responsible for pyroptotic cell swelling. Interestingly, although V2 O5 induces IL-1β release and delays caspase 1 activation by vanadium ion interference in membrane Na+ /K+ adenosine triphosphate (ATP)ase activity, the major cell death mechanism in KC (and Hepa 1-6) is caspase 3 mediated apoptosis. These findings improve the understanding of the mechanisms of metal-based engineered nanomaterial (ENM) toxicity in liver cells toward comprehensive safety evaluation.

Nonclinical regulatory immunotoxicity testing of nanomedicinal products: Proposed strategy and possible pitfalls

Various nanomedicinal products (NMPs) have been reported to induce an adverse immune response, which may be related to their tendency to accumulate in or target cells of the immune system. Therefore, before their market authorization, NMPs should be thoroughly evaluated for their immunotoxic potential. Nonclinical regulatory immunotoxicity testing of nonbiological medicinal products, including NMPs, is currently performed by following the guideline S8 “Immunotoxicity Studies for Human Pharmaceuticals” of the International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use (ICH). However, this guideline does not cover all the immunotoxicity endpoints reported for NMPs in the literature, such as complement activation related pseudo allergy, hypersensitivity and immunosuppression. In addition, ICH‐S8 does not provide any nanospecific testing considerations, which is important given their tendency to interfere with many commonly used toxicity assays. We therefore propose a nonclinical regulatory immunotoxicity assessment strategy, which considers the immunotoxicity endpoints currently missing in the ICH‐S8. We also list the known pitfalls related to the testing of NMPs and how to tackle them. Next to defining the relevant physicochemical and pharmacokinetic properties of the NMP and its intended use, the proposed strategy includes an in vitro assay battery addressing various relevant immunotoxicity endpoints. A weight of evidence evaluation of this information can be used to shape the type and design of further in vivo investigations. The final outcome of the immunotoxicity assessment can be included in the overall risk assessment of the NMP and provide alerts for relevant endpoints to address during clinical investigation.

This article is categorized under:

Toxicology and Regulatory Issues in Nanomedicine > Regulatory and Policy Issues in Nanomedicine

Toxicology and Regulatory Issues in Nanomedicine > Toxicology of Nanomaterials

Macrophage M1/M2 polarization

Macrophages can be affected by a variety of factors to change their phenotype and thus affect their function. Activated macrophages are usually divided into two categories, M1-like macrophages and M2-like macrophages. Both M1 macrophages and M2 macrophages are closely related to inflammatory responses, among which M1 macrophages are mainly involved in pro-inflammatory responses and M2 macrophages are mainly involved in anti-inflammatory responses. Improving the inflammatory environment by modulating the activation state of macrophages is an effective method for the treatment of diseases. In this review, we analyzed the mechanism of macrophage polarization from the tumor microenvironment, nanocarriers, nuclear receptor PPARγ, phagocytosis, NF-κB signaling pathways, and other pathways.

Proinflammatory Effect of Carbon-Based Nanomaterials: In Vitro Study on Stimulation of Inflammasome NLRP3 via Destabilisation of Lysosomes

Carbon-based nanomaterials (C-BNM) have recently attracted an increased attention as the materials with potential applications in industry and medicine. Bioresistance and proinflammatory potential of C-BNM is the main obstacle for their medicinal application which was documented in vivo and in vitro. However, there are still limited data especially on graphene derivatives such as graphene platelets (GP). In this work, we compared multi-walled carbon nanotubes (MWCNT) and two different types of pristine GP in their potential to activate inflammasome NLRP3 (The nod-like receptor family pyrin domain containing 3) in vitro. Our study is focused on exposure of THP-1/THP1-null cells and peripheral blood monocytes to C-BNM as representative models of canonical and alternative pathways, respectively. Although all nanomaterials were extensively accumulated in the cytoplasm, increasing doses of all C-BNM did not lead to cell death. We observed direct activation of NLRP3 via destabilization of lysosomes and release of cathepsin B into cytoplasm only in the case of MWCNTs. Direct activation of NLRP3 by both GP was statistically insignificant but could be induced by synergic action with muramyl dipeptide (MDP), as a representative molecule of the family of pathogen-associated molecular patterns (PAMPs). This study demonstrates a possible proinflammatory potential of GP and MWCNT acting through NLRP3 activation.

Silica dioxide nanoparticles aggravate airway inflammation in an asthmatic mouse model via NLRP3 inflammasome activation

Silica dioxide nanoparticles (SiONPs) are mainly used in the rubber industry; however, they are a major air pollutant in Asia. Thus, extensive research on this issue is required. In this study, we investigated the effects of SiONPs on asthma aggravation and elucidated the underlying mechanism using ovalbumin (OVA)-induced asthmatic mice model and in NCI-H292 cells. Mice exposed to SiONPs showed markedly increased Penh values, inflammatory cell counts, and inflammatory cytokine levels compared to OVA-induced asthmatic mice. Exposure to SiONPs also induced additional airway inflammation and mucus secretion with increases in protein expression levels of thioredoxin-interacting protein (TXNIP), NOD-like receptor pyrin domain-containing 3 (NLRP3) inflammasome, and interleukin (IL)-1β compared to those in OVA-induced asthmatic mice. Treatment of SiONPs in NCI-H292 cells also significantly increased mRNA expression levels of inflammatory cytokines accompanied with elevation in the levels of TXNIP, NLRP3 inflammasome, and IL-1β proteins in a concentration-dependent manner. Taken together, exposure to SiONPs aggravated asthma development, which is closely related to inflammasome activation. Our results provide useful information about the toxicological effects of SiONPs on asthma exacerbation and suggest the need to avoid SiONP exposure especially in individuals with respiratory diseases.

Small and dangerous? Potential toxicity mechanisms of common exposure particles and nanoparticles

We are continuously exposed to large numbers of non-biological, persistent particulates through dermal, oral and inhalation routes. At sizes perfect for cell interactions, such modern particle exposures are derived from human engineering either purposefully (e.g. additives/excipients) or inadvertently (e.g. pollution). Whether oral or dermal exposure to common particles has significantly adverse effects is not yet known. However, relationships between increased morbidity or mortality and airborne particle exposure are well established. Large nanoparticles and microparticles adsorb environmental molecules, including antigens and allergens, and deliver them to cells potentially with an adjuvant effect. Smaller nanoparticles may have enhanced redox activity due to increased surface areas or band gap effects. Under some circumstances, ultrasmall nanoparticles can ligate cellular receptors or interact with other cell machinery and drive distinct cell signalling. These, as well as the potential for inflammasome activation, are discussed as feasible pathways to understanding or de-bunking particle toxicity.

Model-Based Nanoengineered Pharmacokinetics of Iron-Doped Copper Oxide for Nanomedical Applications

The progress in nanomedicine (NM) using nanoparticles (NPs) is mainly based on drug carriers for the delivery of classical chemotherapeutics. As low NM delivery rates limit therapeutic efficacy, an entirely different approach was investigated. A homologous series of engineered CuO NPs was designed for dual purposes (carrier and drug) with a direct chemical composition-biological functionality relationship. Model-based dissolution kinetics of CuO NPs in the cellular interior at post-exposure conditions were controlled through Fe-doping for intra/extra cellular Cu2+ and biological outcome. Through controlled ion release and reactions taking place in the cellular interior, tumors could be treated selectively, in vitro and in vivo. Locally administered NPs enabled tumor cells apoptosis and stimulated systemic anti-cancer immune responses. We clearly show therapeutic effects without tumor cells relapse post-treatment with 6 % Fe-doped CuO NPs combined with myeloid-derived suppressor cell silencing.

In Vivo Metabolic Response upon Exposure to Gold Nanorod Core/Silver Shell Nanostructures: Modulation of Inflammation and Upregulation of Dopamine

With the increasing applications of silver nanoparticles (Ag NPs), the concerns of widespread human exposure as well as subsequent health risks have been continuously growing. The acute and chronic toxicities of Ag NPs in cellular tests and animal tests have been widely investigated. Accumulating evidence shows that Ag NPs can induce inflammation, yet the overall mechanism is incomplete. Herein, using gold nanorod core/silver shell nanostructures (Au@Ag NRs) as a model system, we studied the influence on mice liver and lungs from the viewpoint of metabolism. In agreement with previous studies, Au@Ag NRs' intravenous exposure caused inflammatory reaction, accompanying with metabolic alterations, including energy metabolism, membrane/choline metabolism, redox metabolism, and purine metabolism, the disturbances of which contribute to inflammation. At the same time, dopamine metabolism in liver was also changed. This is the first time to observe the production of dopamine in non-neural tissue after treatment with Ag NPs. As the upregulation of dopamine resists inflammation, it indicates the activation of antioxidant defense systems against oxidative stress induced by Au@Ag NRs. In the end, our findings deepened the understanding of molecular mechanisms of Ag NPs-induced inflammation and provide assistance in the rational design of their biomedical applications.

Effective fraction of Bletilla striata reduces the inflammatory cytokine production induced by water and organic extracts of airborne fine particulate matter (PM2.5) in vitro

BACKGROUND

Bletilla striata is a traditional Chinese medicine used to treat hemorrhage, scald, gastric ulcer, pulmonary diseases and inflammations. In this study, we investigated bioactivity of the effective fraction of B. striata (EFB) in reducing the inflammatory cytokine production induced by water or organic extracts of PM_2.5.

METHODS

PM_2.5 extracts were collected and analyzed by chromatographic system and inductively coupled plasma mass spectrometer. Cell viability was measured using MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) assay, and cell supernatant was analyzed by flow cytometry, ELISA, and qRT-PCR in cultured mouse macrophage cell line RAW264.7 treated with EFB and PM_2.5 extracts. Expressions of nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) signaling pathway were measured by Western blot.

RESULTS

PM_2.5 composition is complex and the toxicity of PM_2.5 extracts were not noticeable. The treatment of EFB at a wide dose-range of 0-40 μg/mL did not cause significant change of RAW264.7 cell proliferation. EFB pretreatment decreased the inflammatory cytokines in the macrophage. Further analysis showed that EFB significantly attenuated PM_2.5-induced proinflammatory protein expression and downregulated the levels of phosphorylated NF-κBp65, inhibitor of kappa B (IκB)-α, c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinase (ERK), and p38.

CONCLUSIONS

Our study demonstrated the potential effectiveness of B. striata extracts for treating PM_2.5-triggered pulmonary inflammation.

Surface Modification of Stöber Silica Nanoparticles with Controlled Moiety Densities Determines Their Cytotoxicity Profiles in Macrophages

Physicochemical properties of nanomaterials play important roles in determining their toxicological profiles during nano-biointeraction. Among them, surface modification is one of the most effective manners to tune the cytotoxicity induced by nanomaterials. However, currently, there is no consistency in surface modification including moiety types and quantities considering the conflicting toxicological profiles of particles across different studies. In this study, in order to systematically investigate how the moiety density affects cytotoxicity of NPs, we chose three different types of functional groups, that is, -NH₂, -COOH, and -PEG, and further controlled their densities on modified Stöber silica nanoparticles (NPs). We demonstrated that densities of functional groups could significantly affect the cytotoxicities of Stöber silica NPs. Regardless of the types of functional groups, high grafting densities could ameliorate the cytotoxicities induced by Stöber silica NPs in macrophages, for example, J774A.1 and N9 cells. When equal amounts of functional groups were present, the cell viability increased in the order of -COOH < -NH₂ < -PEG. Furthermore, it was shown that surface modification could significantly affect the quantities of the surface silanol, which is the determining factor that affects their cytotoxicity. These results show that it is critical to control the surface moiety both quantitatively and qualitatively, which can tune the interaction outcomes at the nano-bio interface. The results found in this article provide useful guidance to adjust nanomaterial cytotoxicity for safer biomedical applications.

A Safe-by-Design Strategy towards Safer Nanomaterials in Nanomedicines

The marriage of nanotechnology and medicine offers new opportunities to fight against human diseases. Benefiting from their unique optical, thermal, magnetic, or redox properties, a wide range of nanomaterials have shown potential in applications such as diagnosis, drug delivery, or tissue repair and regeneration. Despite the considerable success achieved over the past decades, the newly emerging nanomedicines still suffer from an incomplete understanding of their safety risks, and of the relationships between their physicochemical characteristics and safety profiles. Herein, the most important categories of nanomaterials with clinical potential and their toxicological mechanisms are summarized, and then, based on this available information, an overview of the principles in developing safe-by-design nanomaterials for medical applications and of the recent progress in this field is provided. These principles may serve as a starting point to guide the development of more effective safe-by-design strategies and to help identify the major knowledge and skill gaps.

Nano-bio interactions: a neutrophil-centric view

Neutrophils are key components of the innate arm of the immune system and represent the frontline of host defense against intruding pathogens. However, neutrophils can also cause damage to the host. Nanomaterials are being developed for a multitude of different purposes and these minute materials may find their way into the body through deliberate or inadvertent exposure; understanding nanomaterial interactions with the immune system is therefore of critical importance. However, whereas numerous studies have focused on macrophages, less attention is devoted to nanomaterial interactions with neutrophils, the most abundant leukocytes in the blood. We discuss the impact of engineered nanomaterials on neutrophils and how neutrophils, in turn, may digest certain carbon-based materials such as carbon nanotubes and graphene oxide. We also discuss the role of the corona of proteins adsorbed onto the surface of nanomaterials and whether nanomaterials are sensed as pathogens by cells of the immune system.

Assessment of neurotoxicity induced by different-sized Stöber silica nanoparticles: induction of pyroptosis in microglia

With the wide application of Stöber silica nanoparticles and their ability to access the brain, it is crucial to evaluate their neurotoxicity. In this study, we used three in vitro model cells, i.e., N9, bEnd.3 and HT22 cells, representing microglia, microendothelial cells and neurons, respectively, to assess the neurotoxicity of Stöber silica nanoparticles with different sizes. We found that Stöber silica nanoparticles almost had no effect on the viability of bEnd.3 and HT22 cells. In contrast, they induced size-dependent toxicity in N9 cells, which represent the residential macrophages of the central nervous system. Further mechanistic study demonstrated that the toxicity in N9 cells was related to their surface silanol display. In addition, we demonstrated that Stöber silica nanoparticles induced the production of mitochondrial ROS, release of IL-1β, cleavage of GSDMD, and occurrence of pyroptosis in N9 cells. Features of pyroptosis were also observed in primary microglia and macrophage J774A.1. In conclusion, these findings were helpful for the safety consideration of Stöber silica nanoparticles considering their wide applications in our daily life.

Toxic effects and involved molecular pathways of nanoparticles on cells and subcellular organelles

Owing to the increasing application of engineered nanoparticles (NPs), besides the workplace, human beings are also exposed to NPs from nanoproducts through the skin, respiratory tract, digestive tract and vein injection. This review states pathways of cellular uptake, subcellular distribution and excretion of NPs. The uptake pathways commonly include phagocytosis, micropinocytosis, clathrin- and caveolae-mediated endocytosis, scavenger receptor-related pathway, clathrin- or caveolae-independent pathway, and direct penetration or insertion. Then the ability of NPs to decrease cell viability and metabolic activity, change cell morphology, and destroy cell membrane, cytoskeleton and cell function was presented. In addition, the lowest dose decreasing cell metabolic viability compared with the control or IC₅₀ of silver, titanium dioxide, zinc oxide, carbon black, carbon nanotubes, silica, silicon NPs and cadmium telluride quantum dots to some cell lines was gathered. Next, this review attempts to increase our understanding of NP-caused adverse effects on organelles, which have implications in mitochondrial dysfunction, endoplasmic reticulum stress and lysosomal rupture. In particular, the disturbance of mitochondrial biogenesis and mitochondrial dynamic fusion-fission, mitophagy and cytochrome c-dependent apoptosis are involved. In addition, prolonged endoplasmic reticulum stress will result in apoptosis. Rupture of the lysosomal membrane was associated with inflammation, and both induction of autophagy and blockade of autophagic flow can result in cytotoxicity. Finally, the network mechanism of the combined action of multiple organelle dysfunction, apoptosis, autophagy and oxidative stress was discussed.

The neurotoxicity induced by engineered nanomaterials

Engineered nanomaterials (ENMs) have been widely used in various fields due to their novel physicochemical properties. However, the use of ENMs has led to an increased exposure in humans, and the safety of ENMs has attracted much attention. It is universally acknowledged that ENMs could enter the human body via different routes, eg, inhalation, skin contact, and intravenous injection. Studies have proven that ENMs can cross or bypass the blood-brain barrier and then access the central nervous system and cause neurotoxicity. Until now, diverse in vivo and in vitro models have been developed to evaluate the neurotoxicity of ENMs, and oxidative stress, inflammation, DNA damage, and cell death have been identified as being involved. However, due to various physicochemical properties of ENMs and diverse study models in existing studies, it remains challenging to establish the structure-activity relationship of nanomaterials in neurotoxicity. In this paper, we aimed to review current studies on ENM-induced neurotoxicity, with an emphasis on the molecular and cellular mechanisms involved. We hope to provide a rational material design strategy for ENMs when they are applied in biomedical or other engineering applications.

Carbon monoxide releasing molecule-2 protects against particulate matter-induced lung inflammation by inhibiting TLR2 and 4/ROS/NLRP3 inflammasome activation

Exposure to airborne particulate matter (PM) not only causes lung inflammation and chronic respiratory diseases, but also increases the incidence and mortality of cardiopulmonary diseases. The nucleotide-binding domain and leucine-rich repeat protein 3 (NLRP3) inflammasome activation has been shown to play a critical role in the formation of many chronic disorders. On the other hand, carbon monoxide (CO) has been shown to possess anti-inflammatory and antioxidant effects in many tissues and organs. Here, we investigated the effects and mechanisms of carbon monoxide releasing molecule-2 (CORM-2) on PM-induced inflammatory responses in human pulmonary alveolar epithelial cells (HPAEpiCs). We found that PM induced C-reactive protein (CRP) expression, NLRP3 inflammasome activation, IL-1β secretion, and caspase-1 activation, which were inhibited by pretreatment with CORM-2. In addition, transfection with siRNA of Toll-like receptor 2 (TLR2) or TLR4 and pretreatment with an antioxidant (N-acetyl-cysteine, NAC), the inhibitor of NADPH oxidase (diphenyleneiodonium, DPI), or a mitochondria-specific superoxide scavenger (MitoTEMPO) reduced PM-induced inflammatory responses. CORM-2 also inhibited PM-induced NADPH oxidase activity and NADPH oxidase- and mitochondria-derived ROS generation. However, pretreatment with inactivate CORM-2 (iCORM-2) had no effects on PM-induced inflammatory responses. Finally, we showed that CORM-2 inhibited PM-induced CRP, NLRP3 inflammasome, and ASC protein expression in the lung tissues of mice and IL-1β levels in the serum of mice. PM-enhanced leukocyte count in bronchoalveolar lavage fluid in mice was reduced by CORM-2. The results of this study suggested a protective role of CORM-2 in PM-induced lung inflammation by inhibiting the TLR2 and TLR4/ROS-NLRP3 inflammasome-CRP axial.

Vaccine adjuvants: Understanding the structure and mechanism of adjuvanticity

In conjugate, inactivated, recombinant, and toxoid vaccines, adjuvants are extensively and essentially used for enhanced and long-lasting protective immune responses. Depending on the type of diseases and immune responses required, adjuvants with different design strategies are developed. With aluminum salt-based adjuvants as the most used ones in commercial vaccines, other limited adjuvants, e.g., AS01, AS03, AS04, CpG ODN, and MF59, are used in FDA-approved vaccines for human use. In this paper, we review the uses of different adjuvants in vaccines including the ones used in FDA-approved vaccines and vaccines under clinical investigations. We discuss how adjuvants with different formulations could affect the magnitude and quality of adaptive immune response for optimized protection against specific pathogens. We emphasize the molecular mechanisms of various adjuvants, with the aim to establish structure-activity relationships (SARs) for designing more effective and safer adjuvants for both preventative and therapeutic vaccines.

The Overexpression of Sirtuin1 (SIRT1) Alleviated Lipopolysaccharide (LPS)-Induced Acute Kidney Injury (AKI) via Inhibiting the Activation of Nucleotide-Binding Oligomerization Domain-Like Receptors (NLR) Family Pyrin Domain Containing 3 (NLRP3) Inflammasome

Background

Sepsis-induced acute kidney injury (AKI) is threatening the patients with sepsis, and nucleotide-binding oligomerization domain-like receptors (NLR) family pyrin domain containing 3 (NLRP3) inflammasome is considered to play a critical role in this complication of sepsis and might be regulated by sirtuin1 (SIRT1). Thus, we explored the roles of NLRP3 and SIRT1 in the lipopolysaccharide (LPS)-induced AKI in the HK-2 cell line.

Material/Methods

Cell viability was assessed by Cell Counting Kit-8 (CCK-8). Apoptosis rate was measured by flow cytometry. Protein levels of interleukin (IL)-1β and IL-18 were tested by enzyme-linked immunosorbent assay (ELISA) and NLRP3, cleaved caspase-1, caspase-1 were tested by western blot. The mRNA levels of IL-1β, IL-18, and SIRT1 were quantified by qPCR.

Results

LPS could decrease cell viability and the expression of SIRT1 and elevate the expressions of IL-1β, IL-18, NLRP3, and cleaved caspase-1. However, the overexpression of SIRT1 could upregulate cell viability and expression of caspase-1 and downregulate apoptosis rate, expressions of NLRP3, IL-1β, IL-18, and cleaved caspase-1.

Conclusions

NLRP3 inflammasome could act as a critical regulator promoting the process of AKI induced by LPS, and the overexpression of SIRT1 might be able to suppress the activation of NLRP3 and therefore resist the kidney injury, showing promise to be used as a target in the treatment of sepsis-induced AKI.

Membrane fusogenic lysine type lipid assemblies possess enhanced NLRP3 inflammasome activation potency

Lysine (K) type cationic lipid with a propyl spacer and ditetradecyl hydrophobic moieties composing liposomes, K3C14, previously studied for gene delivery, were reported to activate the NLRP3 inflammasomes in human macrophages via the conventional phagolysosomal pathway. In this study, K3C16, a propyl spacer bearing lysine type lipids with dihexadecyl moieties (an extension of two hydrocarbon tail length) were compared with K3C14 as liposomes. Such a small change in tail length did not alter the physical properties such as size distribution, zeta potential and polydispersity index (PDI). The NLRP3 activation potency of K3C16 was shown to be 1.5-fold higher. Yet, the toxicity was minimal, whereas K3C14 has shown to cause significant cell death after 24 h incubation. Even in the presence of endocytosis inhibitors, cytochalasin D or dynasore, K3C16 continued to activate the NLRP3 inflammasomes and to induce IL-1β release. To our surprise, K3C16 liposomes were confirmed to fuse with the plasma membrane of human macrophages and CHO-K1 cells. It is demonstrated that the change in hydrophobic tail length by two hydrocarbons drastically changed a cellular entry route and potency in activating the NLRP3 inflammasomes.

Role of the thioredoxin interacting protein in diabetic nephropathy and the mechanism of regulating NOD‑like receptor protein 3 inflammatory corpuscle

Inflammatory response serves an important role in diabetic nephropathy (DN); however, the mechanism of inflammatory response results in renal damage is not yet clear. The aim of the present study was to investigate the role of the thioredoxin interacting protein (TXNIP)/NOD‑like receptor protein 3 (NLRP3) axis‑mediated activation of NLRP3 inflammasome in DN. A diabetic rat model was induced by streptozotocin injection. Hematoxylin and eosin (H&E) staining and streptavidin‑peroxidase staining were then used to examine the kidney tissue morphology, and TXNIP and NLRP3 protein expression levels, respectively. Furthermore, RNA interference technology was applied to silence the TXNIP gene. TXNIP and NLRP3 inflammasome activation‑associated proteins and mRNAs were detected by western blot analysis and RT‑qPCR, respectively. Enzyme‑linked immunosorbent assay was also used to examine interleukin (IL)‑1 and IL‑18 expression, while flow cytometry was performed to detect reactive oxygen species production. The data revealed that TXNIP and NLRP3 were overexpressed in kidney tissue of DN rats, and the level of antioxidant genes was downregulated. It was also observed that glucose promoted TXNIP expression and activation of NLRP3 inflammasome in a time‑dependent and dose‑dependent manner, therefore promoting inflammatory responses. Silencing of TXNIP gene resulted in the downregulation of NLRP3 inflammasome activation, and inhibited the expression levels of IL‑1 and IL‑18 in a high‑glucose environment. Furthermore, low expression of TXNIP promoted the levels of antioxidant genes and reduced the ROS levels. Taken together, the high‑glucose environment was able to upregulated the level of inflammatory factors by promoting the expression of TXNIP and the activation of NLRP3 inflammasome, consequently participating in DN.

Y2O3 Nanoparticles Caused Bone Tissue Damage by Breaking the Intracellular Phosphate Balance in Bone Marrow Stromal Cells

Y₂O₃ nanoparticles (NPs) have become great promising products for numerous applications in nanoscience especially for biomedical application, therefore increasing the probability of human exposure and gaining wide attention in biosecurity. It is well known that rare earth (RE) materials are deposited in the bone and excreted very slowly. Nevertheless, the effect of Y₂O₃-based NPs on bone metabolism has not been exactly known yet. In the present study, the effects of Y₂O₃ NPs on bone marrow stromal cells (BMSCs) and bone metabolism in mice after intravenous injection were studied. The results demonstrated that Y₂O₃ NPs could be taken up into BMSCs and localized in acidifying intracellular lysosomes and underwent dissolution and transformation from Y₂O₃ to YPO₄, which could lead to a break in the intracellular phosphate balance and induce lysosomal- and mitochondrial-dependent apoptosis pathways. Furthermore, after being administered to mice, a higher concentration of yttrium occurred in bone, which caused the apoptosis of bone cells and induced the destruction of bone structure. However, the formation of a YPO₄ coating on the surface of Y₂O₃ NPs by pretreatment of Y₂O₃ NPs in lysosome-simulated body fluid could observably decrease the toxicity in vivo and in vitro. This study may be useful for practical application of Y₂O₃ NPs in the biomedical field.

Impact of Morphology on Iron Oxide Nanoparticles-Induced Inflammasome Activation in Macrophages

Inflammasomes, a critical component of the innate immune system, mediate much of the inflammatory response manifested by engineered nanomaterials. Iron oxide nanoparticles (IONPs), a type of nanoparticles that have gained widespread acceptance in preclinical and clinical settings, are known to induce inflammasome activation, but how morphology affects the inflammasome-activating property of IONPs has not been addressed. In this report, we have synthesized four morphologically distinct IONPs having the same aspect ratio and similar surface charge, thus offering an ideal system to assess the impact of morphology on nanoparticle-elicited biological effect. We show that morphology was a critical determinant for IONP-induced IL-1β release and pyroptosis, with the octapod and plate IONPs exhibiting significantly higher activity than the cube and sphere IONPs. The inflammasome-activating capacity of different IONPs correlated with their respective ability to elicit intracellular reactive oxygen species generation, lysosomal damage, and potassium efflux, three well-known mechanisms for nanoparticle-facilitated inflammasome activation. Furthermore, we demonstrate that the release of IL-1β induced by IONPs was only partly mediated by NLRP3, suggesting that inflammasomes other than NLRP3 are also involved in IONP-induced inflammasome activation. Our results may have implications for designing safer nanoparticles for in vivo applications.

NLRP3 inflammasome activation and lung fibrosis caused by airborne fine particulate matter

Airborne fine particulate matter (PM_2.5) has been known capable of causing lung inflammation and fibrosis, as a result of a series of chronic respiration diseases. Although NLRP3 inflammasome activation is essential for development of many chronic diseases, the relationship between PM_2.5-induced toxicological effect and NLRP3 inflammasome activation is rarely investigated. Since PM_2.5 contains a large population of nanosized materials and many types of nanomaterials can activate NLRP3 inflammasome, the NLRP3 inflammasome activation and lung fibrosis induced by PM_2.5 were investigated in the present study. PM_2.5 was found capable of causing weak cell death but potent IL-1β secretion in THP-1 cells, which was involved in NLRP3 inflammasome activation as evidenced by Z-YVAD-FMK inhibited IL-1β secretion and overexpressed ASC and NLRP3 protein in PM_2.5 treated cells. PM_2.5 could be internalized into cells through multiple endocytosis processes, such as phagocytosis and pinocytosis (macropinocytosis, clathrin- and caveolin-mediated endocytosis), and activate NLRP3 inflammasome through cathepsin B release, ROS production, and potassium efflux. After 21 days of exposure to PM_2.5 through oropharyngeal aspiration, Balb/c mice showed increased IL-1β and TGF-β1 levels in the bronchoalveolar lavage fluid (BALF) of lung and significant collagen deposition around small airways of mice, suggesting potential lung inflammation and pulmonary fibrosis.

The toxicity of silica nanoparticles to the immune system

Silicon-based materials and their oxides are widely used in drug delivery, dietary supplements, implants and dental fillers. Silica nanoparticles (SiNPs) interact with immunocompetent cells and induce immunotoxicity. However, the toxic effects of SiNPs on the immune system have been inadequately reviewed. The toxicity of SiNPs to the immune system depends on their physicochemical properties and the cell type. Assessments of immunotoxicity include determining cell dysfunctions, cytotoxicity and genotoxicity. This review focuses on the immunotoxicity of SiNPs and investigates the underlying mechanisms. The main mechanisms were proinflammatory responses, oxidative stress and autophagy. Considering the toxicity of SiNPs, surface and shape modifications may mitigate the toxic effects of SiNPs, providing a new way to produce these nanomaterials with less toxic impaction.

Review of in vitro toxicological research of quantum dot and potentially involved mechanisms

Quantum dots (QDs) are one of emerging engineering nanomaterials (NMs) with advantageous properties which can act as candidates for clinical imaging and diagnosis. Nevertheless, toxicological studies have proved that QDs for better or worse pose threats to diverse systems which are attributed to the release of metal ion and specific characteristics of nanoparticles (NPs), hampering the wide use of QDs to biomedical area. It has been postulated that mechanisms of toxicity evoked by QDs have implications in oxidative stress, reactive oxygen species (ROS), inflammation and release of metal ion. Meanwhile, DNA damage and disturbance of subcellular structures would occur during QDs treatment. This review is intended to conclude the cytotoxicity of QDs in multiple systems, as well as the potential mechanisms on the basis of recent literatures. Finally, toxicity-related factors are clarified, among which chirality seems to be a newly proposed influence factor that determines the destiny of cells in response to QDs. However, details of interaction between QDs and cells have not been well elucidated. Given that molecular mechanisms of QDs-induced toxicity are still not clearly elucidated, further research should be required for this meaningful topic.

Dysfunction of various organelles provokes multiple cell death after quantum dot exposure

Quantum dots (QDs) are different from the materials with the micrometer scale. Owing to the superiority in fluorescence and optical stability, QDs act as possible diagnostic and therapeutic tools for application in biomedical field. However, potential threats of QDs to human health hamper their wide utilization in life sciences. It has been reported that oxidative stress and inflammation are involved in toxicity caused by QDs. Recently, accumulating research unveiled that disturbance of subcellular structures plays a magnificent role in cytotoxicity of QDs. Diverse organelles would collapse during QD treatment, including DNA damage, endoplasmic reticulum stress, mitochondrial dysfunction and lysosomal rupture. Different forms of cellular end points on the basis of recent research have been concluded. Apart from apoptosis and autophagy, a new form of cell death termed pyroptosis, which is finely orchestrated by inflammasome complex and gasdermin family with secretion of interleukin-1 beta and interleukin-18, was also summarized. Finally, several potential cellular signaling pathways were also listed. Activation of Toll-like receptor-4/myeloid differentiation primary response 88, nuclear factor kappa-light-chain-enhancer of activated B cells and NACHT, LRR and PYD domains-containing protein 3 inflammasome pathways by QD exposure is associated with regulation of cellular processes. With the development of QDs, toxicity evaluation is far behind its development, where specific mechanisms of toxic effects are not clearly defined. Further studies concerned with this promising area are urgently required.

Oxidative Stress and Inflammation Induced by Environmental and Psychological Stressors: A Biomarker Perspective

SIGNIFICANCE

The environment can elicit biological responses such as oxidative stress (OS) and inflammation as a consequence of chemical, physical, or psychological changes. As population studies are essential for establishing these environment-organism interactions, biomarkers of OS or inflammation are critical in formulating mechanistic hypotheses. Recent Advances: By using examples of stress induced by various mechanisms, we focus on the biomarkers that have been used to assess OS and inflammation in these conditions. We discuss the difference between biomarkers that are the result of a chemical reaction (such as lipid peroxides or oxidized proteins that are a result of the reaction of molecules with reactive oxygen species) and those that represent the biological response to stress, such as the transcription factor NRF2 or inflammation and inflammatory cytokines.

CRITICAL ISSUES

The high-throughput and holistic approaches to biomarker discovery used extensively in large-scale molecular epidemiological exposome are also discussed in the context of human exposure to environmental stressors.

FUTURE DIRECTIONS

We propose to consider the role of biomarkers as signs and to distinguish between signs that are just indicators of biological processes and proxies that one can interact with and modify the disease process. Antioxid. Redox Signal. 28, 852-872.

Polymeric Nanoparticles Induce NLRP3 Inflammasome Activation and Promote Breast Cancer Metastasis

Polymeric nanoparticles gain enormous interests in cancer therapy. Polyethylenimine (PEI) 25 kD is well known for its high transfection efficiency and cytotoxicity. PEI-CyD (PC) was previously synthesized by conjugating low molecular PEI (M _w 600) with β-cyclodextrin (β-CyD), which is shown to induce lower cytotoxicity than PEI 25 kD. In the current study, the in vivo immune response of branched PEI 25 kD and PC is investigated. Compared to PC/pDNA, exposure of PEI 25kD/pDNA induces higher level of immune-stimulation evidenced by the increased spleen weight, phagocytic capacity of peritoneal macrophage, and proinflammatory cytokines in serum and liver. Importantly, administration of PEI 25 kD can greatly promote breast cancer metastasis in liver and lung tissues, which correlates with its ability to induce high oxidative stress and NLRP3-inflammasome activation. These results suggest that polymeric nanocarriers have the potential to induce immune-stimulation and cancer metastasis, which may affect their efficiency for cancer therapy.

Experimental models of sarcoidosis

PURPOSE OF REVIEW

Sarcoidosis is a disease caused by a complex combination of genetic susceptibility, immune networks and infectious and/or environmental agents. The onset and phenotypic variability of sarcoidosis remain poorly elucidated, not only due to the lack of clearly identified causes, but also because it is widely considered that no reliable model of this disease is available. In this review, we discuss the various models of granulomatous diseases in order to challenge this assertion.

RECENT FINDINGS

A large number of models of granulomatous diseases are available, both cellular models used to study the natural history of granulomas and experimental animal models mostly developed in rodents.

SUMMARY

Although none of the available models fully reproduces sarcoidosis, most of them generate various data supporting key concepts. Selected models with a high level of confidence among those already published may provide various pieces of the sarcoidosis jigsaw puzzle, whereas clinical data can provide other elements. A 'systems biology' approach for modelling may be a way of piecing together the various pieces of the puzzle. Finally, experimental models and a systemic approach should be considered to be tools for preclinical evaluation of the efficacy of drugs prior to testing in clinical trials.

The Genetic Heterogeneity among Different Mouse Strains Impacts the Lung Injury Potential of Multiwalled Carbon Nanotubes

Genetic variation constitutes an important variable impacting the susceptibility to inhalable toxic substances and air pollutants, as reflected by epidemiological studies in humans and differences among animal strains. While multiwalled carbon nanotubes (MWCNTs) are capable of causing lung fibrosis in rodents, it is unclear to what extent the genetic variation in different mouse strains influence the outcome. Four inbred mouse strains, including C57Bl/6, Balb/c, NOD/ShiLtJ, and A/J, to test the pro-fibrogenic effects of a library of MWCNTs in vitro and in vivo are chosen. Ex vivo analysis of IL-1β production in bone marrow-derived macrophages (BMDMs) as molecular initiating event (MIE) is performed. The order of cytokine production (Balb/c > A/J > C57Bl/6 > NOD/ShiLtJ) in BMDMs is also duplicated during assessment of IL-1β production in the bronchoalveolar lavage fluid of the same mouse strains 40 h after oropharyngeal instillation of a representative MWCNT. Animal test after 21 d also confirms a similar hierarchy in TGF-β1 production and collagen deposition in the lung. Statistical analysis confirms a correlation between IL-1β production in BMDM and the lung fibrosis. All considered, these data demonstrate that genetic background indeed plays a major role in determining the pro-fibrogenic response to MWCNTs in the lung.

Enhanced Immune Adjuvant Activity of Aluminum Oxyhydroxide Nanorods through Cationic Surface Functionalization

Aluminum-salt-based vaccine adjuvants are prevailingly used in FDA-approved vaccines for the prevention of infectious diseases for over eighty years. Despite their safe applications, the mechanisms regarding how the material characteristics affect the interactions at nano-bio interface and immunogenicity remain unclear. Recently, studies have indicated that the activation of NLRP3 inflammasome plays a critical role in inducing adjuvant effects that are controlled by the inherent shape and hydroxyl contents of aluminum oxyhydroxide (AlOOH) nanoparticles; however, the detailed relationship between surface properties and adjuvant effects for these materials remains unknown. Thus, we engineered AlOOH nanorods (ALNRs) with controlled surface functionalization and charge to assess their effects on the activation of NLRP3 inflammasome in vitro and the potentiation of immunogenicity in vivo. It is demonstrated that NH₂-functionalized ALNRs exhibited higher levels of cellular uptake, lysosomal damage, oxidative stress, and NLRP3 inflammasome activation than pristine and SO₃H-functionalized ALNRs in cells. This structure-activity relationship also correlates with the adjuvant activity of the material using ovalbumin (OVA) in a mouse vaccination model. This study demonstrates that surface functionalization of ALNRs is critical for rational design of aluminum-based adjuvants to boost antigen-specific immune responses for more effective and long-lasting vaccination.