In vitro inflammatory effects of hard metal (WC-Co) nanoparticle exposure

Antimicrobial Peptide Identified via Machine Learning Presents Both Potent Antibacterial Properties and Low Toxicity toward Human Cells

Preventing infection is a critical clinical challenge; however, the extensive use of antibiotics has resulted in remarkably increased antibiotic resistance. A variety of antibiotic alternatives including antimicrobial peptides (AMPs) have been studied. Unfortunately, like most conventional antibiotics, most current AMPs have shown significantly high toxicity toward the host, and therefore induce compromised host responses that may lead to negative clinical outcomes such as delayed wound healing. In this study, one of the AMPs with a short length of nine amino acids was first identified via machine learning to present potentially low cytotoxicity, and then synthesized and validated in vitro against both bacteria and mammalian cells. It was found that this short AMP presented strong and fast-acting antimicrobial properties against bacteria like Staphylococcus aureus, one of the most common bacteria clinically, and it targeted and depolarized bacterial membranes. This AMP also demonstrated significantly lower (e.g., 30%) toxicity toward mammalian cells like osteoblasts, which are important cells for new bone formation, compared to conventional antibiotics like gentamicin, vancomycin, rifampin, cefazolin, and fusidic acid at short treatment times (e.g., 2 h). In addition, this short AMP demonstrated relatively low toxicity, similar to osteoblasts, toward an epithelial cell line like BEAS-2B cells.

Tungsten toxicity on kidney tubular epithelial cells induces renal inflammation and M1-macrophage polarization

Tungsten is widely used in medical, industrial, and military applications. The environmental exposure to tungsten has increased over the past several years, and few studies have addressed its potential toxicity. In this study, we evaluated the effects of chronic oral tungsten exposure (100 ppm) on renal inflammation in male mice. We found that 30- or 90-day tungsten exposure led to the accumulation of LAMP1-positive lysosomes in renal tubular epithelial cells. In addition, the kidneys of mice exposed to tungsten showed interstitial infiltration of leukocytes, myeloid cells, and macrophages together with increased levels of proinflammatory cytokines and p50/p65-NFkB subunits. In proximal tubule epithelial cells (HK-2) in vitro, tungsten induced a similar inflammatory status characterized by increased mRNA levels of CSF1, IL34, CXCL2, and CXCL10 and NFkB activation. Moreover, tungsten exposure reduced HK-2 cell viability and enhanced reactive oxygen species generation. Conditioned media from HK-2 cells treated with tungsten induced an M1-proinflammatory polarization of RAW macrophages as evidenced by increased levels of iNOS and interleukin-6 and decreased levels of the M2-antiinflammatory marker CD206. These effects were not observed when RAW cells were exposed to conditioned media from HK-2 cells treated with tungsten and supplemented with the antioxidant N-acetylcysteine (NAC). Similarly, direct tungsten exposure induced M1-proinflammatory polarization of RAW cells that was prevented by NAC co-treatment. Altogether, our data suggest that prolonged tungsten exposure leads to oxidative injury in the kidney ultimately leading to chronic renal inflammation characterized by a proinflammatory status in kidney tubular epithelial cells and immune cell infiltration.

Optimizing THP-1 Macrophage Culture for an Immune-Responsive Human Intestinal Model

Previously established immune-responsive co-culture models with macrophages have limitations due to the dedifferentiation of macrophages in long-term cultures. This study is the first report of a long-term (21-day) triple co-culture of THP-1 macrophages (THP-1m) with Caco-2 intestinal epithelial cells and HT-29-methotrexate (MTX) goblet cells. We demonstrated that high-density seeded THP-1 cells treated with 100 ng/mL phorbol 12-myristate 13-acetate for 48 h differentiated stably and could be cultured for up to 21 days. THP-1m were identified by their adherent morphology and lysosome expansion. In the triple co-culture immune-responsive model, cytokine secretions during lipopolysaccharide-induced inflammation were confirmed. Tumor necrosis factor-alpha and interleukin 6 levels were elevated in the inflamed state, reaching 824.7 ± 130.0 pg/mL and 609.7 ± 139.5 pg/mL, respectively. Intestinal membrane integrity was maintained with a transepithelial electrical resistance value of 336.4 ± 18.0 Ω·cm². Overall, our findings suggest that THP-1m can be effectively employed in models of long-term immune responses in both normal and chronic inflammatory states of the intestinal epithelium, making them a valuable tool for future research on the association between the immune system and gut health.

Investigation of Trace Elements in Vegan Foods by ICP-MS After Microwave Digestion

Veganism is gaining popularity around the world day by day. Vegan nutrition is a diet in which not all animal foods are used. A vegan diet does not contain meat, fish, milk and dairy products, and eggs and consists of vegetables, fruits, grains, legumes, and nuts. Vegan diets maintain energy balances in a wide variety of plant foods. So, health problems can be seen due to nutrient and mineral deficiencies in the long-term continuation of the vegan diet. Due to insufficient intake of vitamins and minerals such as vitamin D, vitamin B12, calcium, iron, and zinc, energy and protein balance in the body may not be achieved by vegan individuals. The contents of aluminum, chromium, manganese, iron, cobalt, nickel, copper, zinc, arsenic, mercury, cadmium, and lead have been analyzed by inductively coupled plasma mass spectrometer (ICP-MS) in 10 different vegan foods purchased from Turkey. Certified reference material (1547 peach leaves) was used for validating the digestion procedure. Dry, wet, and microwave processes were compared, and it was found that the microwave digestion method was the best. Element levels in the analyzed samples were found below the legal limits. The purpose of this work is to investigate the trace element content of various foods used in vegan nutrition.

Cerium dioxide, a Jekyll and Hyde nanomaterial, can increase basal and decrease elevated inflammation and oxidative stress

It was hypothesized that the catalyst nanoceria can increase inflammation/oxidative stress from the basal and reduce it from the elevated state. Macrophages clear nanoceria. To test the hypothesis, M0 (non-polarized), M1- (classically activated, pro-inflammatory), and M2-like (alternatively activated, regulatory phenotype) RAW 264.7 macrophages were nanoceria exposed. Inflammatory responses were quantified by IL-1β level, arginase activity, and RT-qPCR and metabolic changes and oxidative stress by the mito and glycolysis stress tests (MST and GST). Morphology was determined by light microscopy, macrophage phenotype marker expression, and a novel three-dimensional immunohistochemical method. Nanoceria blocked IL-1β and arginase effects, increased M0 cell OCR and GST toward the M2 phenotype and altered multiple M1- and M2-like cell endpoints toward the M0 level. M1-like cells had greater volume and less circularity/roundness. M2-like cells had greater volume than M0 macrophages. The results are overall consistent with the hypothesis.

Effects on white blood cell counts and the NLRP3 inflammasome due to dust and cobalt exposure in the hard metal industry

INTRODUCTION

In light of potential negative health effects of cobalt exposure, a characterization of inflammatory mechanisms in exposed individuals is warranted. The current study investigated cobalt exposure in the Swedish hard metal industry and its relationship to inflammatory markers, including NLRP3 inflammasome activation and white blood cell (WBC) counts.

MATERIALS AND METHODS

Inhalable cobalt and dust exposures, and systemic cobalt levels, were determined for 72 workers in the hard metal industry and linear regression models were applied to correlate exposure to markers of inflammasome activation and WBC counts.

RESULTS

Mean exposures to inhalable dust (0.11 mg/m³) and cobalt (0.0034 mg/m³) were below the Swedish occupational exposure limits, and these low exposures did not correlate with any investigated outcomes. Instead, cobalt blood levels significantly correlated with a ca 10% decrease in IL-18 plasma levels per 10 nM cobalt increase. Furthermore, pre-shift cobalt blood and/or urine levels significantly correlated with some WBC measures, including decreased neutrophil-to-lymphocyte ratio, increased lymphocyte-to-monocyte ratio, and lymphocyte counts.

CONCLUSION

The low inhalable particle exposures had no impact on WBC counts and inflammasome activation. Instead, systemic cobalt levels, which also include skin exposure, demonstrated possible suppressive effects on inflammatory responses in cobalt-exposed individuals in the hard metal industry.

How macrophages respond to two-dimensional materials: a critical overview focusing on toxicity

With wider use of graphene-based materials and other two-dimensional (2 D) materials in various fields, including electronics, composites, biomedicine, etc., 2 D materials can trigger undesired effects at cellular, tissue and organ level. Macrophages can be found in many organs. They are one of the most important cells in the immune system and they are relevant in the study of nanomaterials as they phagocytose them. Nanomaterials have multi-faceted effects on phagocytic immune cells like macrophages, showing signs of inflammation in the form of pro-inflammatory cytokine or reactive oxidation species production, or upregulation of activation markers due to the presence of these foreign bodies. This review is catered to researchers interested in the potential impact and toxicity of 2 D materials, particularly in macrophages, focusing on few-layer graphene, graphene oxide, graphene quantum dots, as well as other promising 2 D materials containing molybdenum, manganese, boron, phosphorus and tungsten. We describe applications relevant to the growing area of 2 D materials research, and the possible risks of ions and molecules used in the production of these promising 2 D materials, or those produced by the degradation and dissolution of 2 D materials.

Wear particles induce a new macrophage phenotype with the potential to accelerate material corrosion within total hip replacement interfaces

Evidence that macrophages can play a role in accelerating corrosion in CoCrMo alloy in total hip replacement (THR) interfaces leads to questions regarding the underlying cellular mechanisms and immunological responses. Hence, we evaluated the role of macrophages in corrosion processes using the cell culture supernatant from different conditions and the effect of wear particles on macrophage dynamics. Monocytes were exposed to CoCrMo wear particles and their effect on macrophage differentiation was investigated by comparisons with M1 and M2 macrophage differentiation. Corrosion associated macrophages (M_CA macrophages) exhibited upregulation of TNF-α, iNOS, STAT-6, and PPARG and down-regulation of CD86 and ARG, when compared to M1 and M2 macrophages. M_CA cells also secreted higher levels of IL-8, IL-1β, IL-6, IL-10, TNF-α, and IL-12p70 than M1 macrophages and/or M2 macrophages. Our findings revealed variation in macrophage phenotype (M_CA) induced by CoCrMo wear particles in generating a chemical environment that induces cell-accelerated corrosion of CoCrMo alloy at THR modular interfaces. STATEMENT OF SIGNIFICANCE: Fretting wear and corrosion within the implant's modular taper junction are prominent causes of implant failure, as they promote the release of corrosion products and subsequent development of adverse local tissue reactions. Being a multifactorial process, several in vitro models have been developed to recreate the in vivo corrosion process, often summarized as mechanically-assisted crevice corrosion. Considering the excellent corrosion properties of CoCrMo alloy, the severity of chemically-generated damage observed at the modular interface has been surprising and poorly understood. The aim of the current study is to provide a better understanding of macrophages and their plasticity at the THR taper interface when they encounter wear debris from CoCrMo alloy. This is a preliminary study along the path towards determining the mechanism(s) of CAC.

Influence of Biocorona Formation on the Transformation and Dissolution of Cobalt Nanoparticles under Physiological Conditions

Cobalt (Co) nanoparticles (NPs) are produced in different applications and unintentionally generated at several occupational and traffic settings. Their diffuse dispersion may lead to interactions with humans and aquatic organisms via different exposure routes that include their transformation/dissolution in biological media. This paper has investigated the particle stability and reactivity of Co NPs (dispersed by sonication prior to exposure) interacting with selected individual biomolecules (amino acids, polypeptides, and proteins) in phosphate-buffered saline (PBS). No or minor adsorption of amino acids (glutamine, glutamic acid, lysine, and cysteine) was observed on the Co NPs, independent of the functional group and charge. Instead, phosphate adsorption resulted in the formation of a surface layer (a corona) of Co phosphate. The adsorption of larger biomolecules (polyglutamic acid, polylysine, lysozyme, and mucin) was evident in parallel with the formation of Co phosphate. The dissolution of the Co NPs was rapid as 35-55% of the particle mass was dissolved within the first hour of exposure. The larger biomolecules suppressed the dissolution initially compared to exposure in PBS only, whereas the dissolution was essentially unaffected by the presence of amino acids, with cysteine as an exception. The formation of Co phosphate on the NP surface reduced the protective properties of the surface oxide of the Co NPs, as seen from the increased levels of the released Co when compared with the nonphosphate-containing saline. The results underline the diversity of possible outcomes with respect to surface characteristics and dissolution of Co NPs in biological media and emphasize the importance of surface interactions with phosphate on the NP characteristics and reactivity.

Biological Effects of Nanoparticles on Macrophage Polarization in the Tumor Microenvironment

Biological interactions between tumor-associated macrophages (TAMs), cancer cells and other cells within the tumor microenvironment contribute to tumorigenesis, tumor growth, metastasis and therapeutic resistance. TAMs can remodel the tumor microenvironment to reduce growth barriers such as the dense extracellular matrix and shift tumors towards an immunosuppressive microenvironment that protects cancer cells from targeted immune responses. Nanoparticles can interrupt these biological interactions within tumors by altering TAM phenotypes through a process called polarization. Macrophage polarization within tumors can shift TAMs from a growth-promoting phenotype towards a cancer cell-killing phenotype that predicts treatment efficacy. Because many types of nanoparticles have been shown to preferentially accumulate within macrophages following systemic administration, there is considerable interest in identifying nanoparticle effects on TAM polarization, evaluating nanoparticle-induced TAM polarization effects on cancer treatment using drug-loaded nanoparticles and identifying beneficial types of nanoparticles for effective cancer treatment. In this review, the macrophage polarization effects of nanoparticles will be described based on their primary chemical composition. Because of their strong macrophage-polarizing and antitumor effects compared to other types of nanoparticles, the effects of iron oxide nanoparticles on macrophages will be discussed in detail. By comparing the macrophage polarization effects of various nanoparticle treatments reported in the literature, this review aims to both elucidate nanoparticle material effects on macrophage polarization and to provide insight into engineering nanoparticles with more beneficial immunological responses for cancer treatment.

Fate and Effect of Nano Tungsten Carbide Cobalt (WCCo) in the Soil Environment: Observing a Nanoparticle Specific Toxicity in Enchytraeus crypticus

Tungsten carbide cobalt (WCCo) nanoparticles (NPs) are widely used in hard metal industries. Pulmonary diseases and risk of cancer are associated with occupational exposure, but knowledge about the environmental fate and effects is virtually absent. In this study, the fate and effects of crystalline WCCo NPs, WC, and Co²⁺ were assessed in the soil model Enchytraeus crypticus, following the standard Enchytraeid Reproduction Test (ERT). An additional 28 day exposure period compared to the ERT (i.e., a total of 56 days) was performed to assess longer-term effects. WCCo NPs affected reproduction at a concentration higher than the corresponding Co based (EC50 = 1500 mg WCCo/kg, equivalent to 128 mg Co/kg). WC showed no negative effect up to 1000 mg W/kg. Maximum uptake of Co was 10-fold higher for CoCl₂ compared to WCCo exposed organisms. Overall toxicity seems to be due to a combined effect between WC and Co. This is supported by the soil bioavailable fraction and biological tissue measurements. Last, results highlight the need to consider longer exposure period of NPs for comparable methods standardized for conventional chemicals.

Integrin-Mediated Interactions Control Macrophage Polarization in 3D Hydrogels

Adverse immune reactions prevent clinical translation of numerous implantable devices and materials. Although inflammation is an essential part of tissue regeneration, chronic inflammation ultimately leads to implant failure. In particular, macrophage polarity steers the microenvironment toward inflammation or wound healing via the induction of M1 and M2 macrophages, respectively. Here, this paper demonstrates that macrophage polarity within biomaterials can be controlled through integrin-mediated interactions between human monocytic THP-1 cells and collagen-derived matrix. Surface marker, gene expression, biochemical, and cytokine profiling consistently indicate that THP-1 cells within a biomaterial lacking cell attachment motifs yield proinflammatory M1 macrophages, whereas biomaterials with attachment sites in the presence of interleukin-4 (IL-4) induce an anti-inflammatory M2-like phenotype and propagate the effect of IL-4 in induction of M2-like macrophages. Importantly, integrin α2β1 plays a pivotal role as its inhibition blocks the induction of M2 macrophages. The influence of the microenvironment of the biomaterial over macrophage polarity is further confirmed by its ability to modulate the effect of IL-4 and lipopolysaccharide, which are potent inducers of M2 or M1 phenotypes, respectively. Thus, this study represents a novel, versatile, and effective strategy to steer macrophage polarity through integrin-mediated 3D microenvironment for biomaterial-based programming.

Nanotoxicity: emerging concerns regarding nanomaterial safety and occupational hard metal (WC-Co) nanoparticle exposure

As the number of commercial and consumer products containing engineered nanomaterials (ENMs) continually rises, the increased use and production of these ENMs presents an important toxicological concern. Although ENMs offer a number of advantages over traditional materials, their extremely small size and associated characteristics may also greatly enhance their toxic potentials. ENM exposure can occur in various consumer and industrial settings through inhalation, ingestion, or dermal routes. Although the importance of accurate ENM characterization, effective dosage metrics, and selection of appropriate cell or animal-based models are universally agreed upon as important factors in ENM research, at present, there is no “standardized” approach used to assess ENM toxicity in the research community. Of particular interest is occupational exposure to tungsten carbide cobalt (WC-Co) “dusts,” composed of nano- and micro-sized particles, in hard metal manufacturing facilities and mining and drilling industries. Inhalation of WC-Co dust is known to cause “hard metal lung disease” and an increased risk of lung cancer; however, the mechanisms underlying WC-Co toxicity, the inflammatory disease state and progression to cancer are poorly understood. Herein, a discussion of ENM toxicity is followed by a review of the known literature regarding the effects of WC-Co particle exposure. The risk of WC-Co exposure in occupational settings and the updates of in vitro and in vivo studies of both micro- and nano-WC-Co particles are discussed.