Immunotoxicity of Silver Nanoparticles (AgNPs) on the Leukocytes of Common Bottlenose Dolphins (Tursiops truncatus)

Nanomaterials in the environment and their pragmatic voyage at various trophic levels in an ecosystem

In the development of nanotechnology, nanomaterials (NMs) have a huge credential in advancing the existing follow-ups of analytical and diagnosis techniques, drug designing, agricultural science, electronics, cosmetics, sports, textiles and water purification. However, NMs have also grasped attention of researchers onto their toxicity. In the present review, initially the development of notable NMs such as metal and metal-oxide nanoparticles (NPs), magnetic NPs, carbon-based NMs and quantum dots intended to be commercialized along with their applications are discussed. This is followed by the current scenario of NMs in the environment to widen the outlook on the concentration of NPs in the environmental compartments and the frequency of organism exposed to NPs at varied trophic levels. In order to understand the physiochemical and morphological significance of NPs in exhibiting toxicity, fate of NPs in the environment is briefly deliberated. This is further geared-up to glance in-sightedly on the organisms starting from primary producer to primary consumer, secondary consumer, tertiary consumer and decomposers encountering NPs in their habitual niche. The state of NPs to which organisms are exposed, mechanism of NP uptake and toxicity, anomalies faced at each trophic level, concentration of NPs that is liable to cause toxicity and, biotransfer of NPs to the next generation and trophic level are detailed. Finally, the future prospects on bioaccumulation and biomagnification of NP-based products are conversed. Thus, the review would be noteworthy in unveiling the significance of NPs in forthcoming years combined with threat towards each organism in an ecosystem.

Physiological values of phagocytic capacity in marine mammals and alterations during pathological situations

The study of the immune function in marine mammals is essential to understand their physiology and can help to improve their welfare in the aquariums. Dedicating efforts to studying marine mammal physiology, pathophysiology, and implementing new diagnostic and therapeutic tools promote progress towards preventive medicine in aquariums by facilitating early detection and treatment of diseases. However, biological and clinical research on marine mammals is currently very limited due to difficult access to these species and their biological samples. With this objective, our group has adapted to marine mammals a commercially available assay routinely used to evaluate the phagocytic capacity of monocytes and granulocytes in human whole blood samples. We adapted IngoflowEx kit to bottlenose dolphins (Tursiops truncatus), beluga whales (Delphinapterus leucas), walruses (Odobenus rosmarus), Patagonian sea lions (Otaria flavescens), and harbor (Phoca vitulina). In this paper, we report the modifications carried out on the original protocol for their correct functioning in marine mammals. We obtained physiological values of phagocytic capacity in each species after repeated sampling for 4 years in various individuals of each species. Specific results revealed that the % phagocytic cells that ingested E.coli in bottlenose dolphins were 59.6 ± 1.27, in walruses 62.6 ± 2.17, in sea lions 57.5 ± 4.3, and in beluga whales 61.7 ± 1.4. In the case of the % phagocytic cells producing respiratory burst in bottlenose dolphins were 34.2 ± 3.6, in walruses 36.3 ± 4.3, in sea lions 40.8 ± 10.2, and in beluga whales 26.3 ± 3.7. These preliminary results can be used as a reference to detect alterations in phagocytic capacity either by immunosuppression or by exacerbation of the response in infectious inflammatory processes. Clinical applicability of the assay was verified in two clinical cases in which Ingoflow was useful to detect immune alterations in two diseased individuals, before and after the onset of clinical signs.

Engineered Nanomaterials for Immunomodulation: A Review

The immune system usually provides a defense against invading pathogenic microorganisms and any other particulate contaminants. Nonetheless, it has been recently reported that nanomaterials can evade the immune system and modulate immunological responses due to their unique physicochemical characteristics. Consequently, nanomaterial-based activation of immune components, i.e., neutrophils, macrophages, and other effector cells, may induce inflammation and alter the immune response. Here, it is essential to distinguish the acute and chronic modulations triggered by nanomaterials to determine the possible risks to human health. Nanomaterials size, shape, composition, surface charge, and deformability are factors controlling their uptake by immune cells and the resulting immune responses. The exterior corona of molecules adsorbed over nanomaterials surfaces also influences their immunological effects. Here, we review current nanoengineering trends for targeted immunomodulation with an emphasis on the design, safety, and potential toxicity of nanomaterials. First, we describe the characteristics of engineered nanomaterials that trigger immune responses. Then, the biocompatibility and immunotoxicity of nanoengineered particles are debated, because these factors influence applications. Finally, future nanomaterial developments in terms of surface modifications, synergistic approaches, and biomimetics are discussed.

Tissue Distribution, Pharmacokinetics, and Effect of Hematological and Biochemical Parameters of Acute Intravenous Administration of Silver Nanoparticles in Rats

The widespread biomedical and commercial applications of silver nanoparticles (AgNPs) have increased their potential for human and environmental exposure and toxicity to human health. The bio-distribution and toxicity of AgNPs in rodents following inhalation, intratracheal instillation, and oral ingestion are well documented; however, little is known about the bio-distribution of intravenously (IV)-administered AgNPs and their organ-specific pathophysiological effects. Here, we investigate the pharmacokinetic pattern and tissue distribution of AgNPs in male rats following IV administration. The animals were humanely sacrificed after 10 min, 1 h, 6 h, 12 h, 24 h, and 168 h of AgNP administration, and the silver (Ag) content was measured from blood samples and various tissues following acid digestion. The AgNPs were readily absorbed and subsequently distributed into most organs predominantly in the colon, small intestine, kidney, and heart after 6 h; however, they were the highest in the spinal cord after 168 h. White blood cells (WBCs) were significantly increased (42-60%) in AgNP-administered animals at all time points except 10 min. Regarding platelets, all AgNP-administered animals showed counts 7.8-39.2% lower, with the lowest count at 168 h post-administration. In the case of lymphocytes (LYMs), the AgNP-treated animals exhibited a count 19.5-41% lower at 10 min and 1 h post-administration; however, the animals at 168 h post-administration showed a count 30.5% more. The mean corpuscular hemoglobin (MCH) counts from the AgNP-treated animals were decreased by 50-62%. The concentrations of aspartate transaminase (AST), urea, and creatinine were increased in the AgNP-treated animals. Taken together, the results suggest that the acute IV administration of AgNPs alters metabolic and hematological parameters in animals and may pose a health risk to humans.

Dolphin leukocytes exhibit an attenuated cytokine response and increase heme oxygenase activity upon exposure to lipopolysaccharides

Cetaceans exhibit physiological adaptations that allowed the transition to aquatic life, including a robust antioxidant defense system that prevents injury from repeated exposure to ischemia/reperfusion events associated with breath-hold diving. The signaling cascades that characterize ischemic inflammation in humans are well characterized. In contrast, cetaceans' molecular and biochemical mechanisms that confer tolerance to inflammatory events are poorly understood. Heme oxygenase (HO) is a cytoprotective protein with anti-inflammatory properties. HO catalyzes the first step in the oxidative degradation of heme. The inducible HO-1 isoform is regulated by various stimuli, including hypoxia, oxidant stress, and inflammatory cytokines. The objective of this study was to compare the response of HO-1 and cytokines to a proinflammatory challenge in leukocytes isolated from humans and bottlenose dolphins (Tursiops truncatus). We measured changes in HO activity and expression, and abundance and expression of interleukin 1 beta (IL-1β), interleukin 6 (IL-6), tumor necrosis factor-alpha (TNF-α), and heme oxygenase 1 (HMOX1) in leukocytes treated with lipopolysaccharide (LPS) for 24 and 48 h. HO activity increased (p < 0.05) in dolphin (48 h) but not human cells. TNF-α expression increased in human (24 h, 48 h), but not dolphin cells following LPS stimulation. LPS-induced cytokine expression was lower in dolphin than in human leukocytes, suggesting a blunted cytokine response in bottlenose dolphin leukocytes treated with LPS. Results suggest species-specific regulation of inflammatory cytokines in leukocytes treated with LPS, which may lead to differential responses to a pro-inflammatory challenge between marine and terrestrial mammals.

Skin Marks in Critically Endangered Taiwanese Humpback Dolphins (Sousa chinensis taiwanensis)

As long-lived apex predators, Indo-Pacific humpback dolphins (Sousa chinensis) are key indicators of marine coastal environmental health. Skin marks can be observed on dorsal body surfaces that are visible during mark-recapture studies that rely on photo-identification (photo-ID) methods. Skin mark prevalence may be an indicator of environmental or anthropogenic stressors in the ecosystem, which may lead to individual and/or population-level health concerns. The prevalence of marks of anthropogenic origin was assessed in the Critically Endangered S. chinensis taiwanensis population along the coasts of central Taiwan. Fifty, twenty-eight, and thirty-four individuals were identified in 2018, 2019, and 2021, respectively. At least one category of injuries was observed in 47 of 57 distinctive individuals (82%), and adults showed a higher prevalence of deep injuries than the other coloration stages. At least one category of skin lesion was observed in 33 of 57 distinctive individuals (58%), and high prevalence of skin lesions was found in mature individuals. Given the difficulty in taking direct observations, skin mark prevalence is proposed as a proxy for estimating habitat health and anthropogenic stressors upon S. chinensis taiwanensis. The moderate-to-high prevalence of skin marks in this study was designated as a warning of risks. This study provides important updated information for the assessment of the health and survival of this population. More effective management measures are urgently needed to reverse the observed population decline.

Flow Cytometry - Sophisticated Tool for Basic Research or/and Routine Diagnosis; Impact of the Complementarity in Both Pre- as Well as Clinical Studies

Flow cytometry is a sophisticated technology used widely in both basic research and as a routine tool in clinical diagnosis. The technology has progressed from single parameter detection in the 1970s and 1980s to high end multicolor analysis, with currently 30 parameters detected simultaneously, allowing the identification and purification of rare subpopulations of cells of interest. Flow cytometry continues to evolve and expand to facilitate the investigation of new diagnostic and therapeutic avenues. The present review gives an overview of basic theory and instrumentation, presents and compares the advantages and disadvantages of conventional, spectral and imaging flow cytometry as well as mass cytometry. Current methodologies and applications in both research, pre- and clinical settings are discussed, as well as potential limitations and future evolution. This finding encourages the reader to promote such relationship between basic science, diagnosis and multidisciplinary approach since the standard methods have limitations (e.g., in differentiating the cells after staining). Moreover, such path inspires future cytometry specialists develop new/alternative frontiers between pre- and clinical diagnosis and be more flexible in designing the study for both human as well as veterinary medicine.

In Vivo Efficacy of Wound Healing under External (Bio)AgNCs Treatment: Localization Case Study in Liver and Blood Tissue

The present study reports on the in vivo application of (Bio)silver nanocomposite formulations (LBPC-AgNCs) on wound healing. Additionally, the present study emphasizes the limited uptake of silver by liver and blood tissues as well as the high viability of PBMCs following external LBPC-AgNCs treatment. The wound closure was monitored via stereoscopic microscope, a localization case study in liver and blood tissue was carried out by (Inductively Coupled Plasma-Mass Spectrometers (ICP/MS), and peripheral blood mononuclear cells (PMBC) viability was determined via flow cytometry technique. The silver formulation was applied externally on the site of the wound infection for a period of ten days. At the beginning of the experiment, a moderate decrease in body weight and atypical behavior was observed. However, during the last period of the experiment, no abnormal mouse behaviors were noticed. The wound-healing process took place in a gradual manner, presenting the regeneration effect at around 30% from the fourth day. From the seventh day, the wounds treated with the silver formulation showed 80% of the wound healing potential. The viability of PBMCs was found to be 97%, whereas the concentrations of silver in the liver and blood samples were determined to be 0.022 µg/g and 9.3 µg/g, respectively. Furthermore, the present report becomes a pilot study in transferring from in vitro to in vivo scale (e.g., medical field application) once LBPC-AgNCs have demonstrated a unique wound healing potential as well as a non-toxic effect on the liver and blood.

Hyaluronic Acid-Silver Nanocomposites and Their Biomedical Applications: A Review

For the last years scientific community has witnessed a rapid development of novel types of biomaterials, which properties made them applicable in numerous fields of medicine. Although nanosilver, well-known for its antimicrobial, anti-angiogenic, anti-inflammatory and anticancer activities, as well as hyaluronic acid, a natural polysaccharide playing a vital role in the modulation of tissue repair, signal transduction, angiogenesis, cell motility and cancer metastasis, are both thoroughly described in the literature, their complexes are still a novel topic. In this review we introduce the most recent research about the synthesis, properties, and potential applications of HA-nanosilver composites. We also make an attempt to explain the variety of mechanisms involved in their action. Finally, we present biocompatible and biodegradable complexes with bactericidal activity and low cytotoxicity, which properties suggest their suitability for the prophylaxis and therapy of chronic wounds, as well as analgetic therapies, anticancer strategies and the detection of chemical substances and malignant cells. Cited studies reveal that the usage of hyaluronic acid-silver nanocomposites appears to be efficient and safe in clinical practice.

Surface Stabilization Affects Toxicity of Silver Nanoparticles in Human Peripheral Blood Mononuclear Cells

Silver nanoparticles (AgNPs) are one of the most investigated metal-based nanomaterials. Their biocidal activity boosted their application in both diagnostic and therapeutic medical systems. It is therefore crucial to provide sound evidences for human-related safety of AgNPs. This study aimed to enhance scientific knowledge with regard to biomedical safety of AgNPs by investigating how their different surface properties affect human immune system.

METHODS

preparation, characterization and stability evaluation was performed for four differently coated AgNPs encompassing neutral, positive and negative agents used for their surface stabilization. Safety aspects were evaluated by testing interaction of AgNPs with fresh human peripheral blood mononuclear cells (hPBMC) by means of particle cellular uptake and their ability to trigger cell death, apoptosis and DNA damages through induction of oxidative stress and damages of mitochondrial membrane.

RESULTS

all tested AgNPs altered morphology of freshly isolated hPBMC inducing apoptosis and cell death in a dose- and time-dependent manner. Highest toxicity was observed for positively-charged and protein-coated AgNPs. Cellular uptake of AgNPs was also dose-dependently increased and highest for positively charged AgNPs. Intracellularly, AgNPs induced production of reactive oxygen species (ROS) and damaged mitochondrial membrane. Depending on the dose, all AgNPs exhibited genotoxic potential.

CONCLUSIONS

this study provides systematic and comprehensive data showing how differently functionalized AgNPs may affect the human immune system. Presented results are a valuable scientific contribution to safety assessment of nanosilver-based blood-contacting medical products.

Role of Beetroot (Beta vulgaris) Juice on Chronic Nanotoxicity of Silver Nanoparticle-Induced Hepatotoxicity in Male Rats

Introduction

Nanoparticles are at the forefront of rapidly developing nanotechnology and have gained much attention for their application as an effective drug delivery system and as a mediated therapeutic agent for cancer. However, the cytotoxicity of nanoparticles is still relatively unknown and, therefore, additional study is required in order to elucidate the potential toxicity of these nanoparticles on cells.

Materials and Methods

Thus, the following work aimed to investigate the capability of Beta vulgaris (beetroot) water extract (BWE; 200 mg/kg) to protect hepatic tissue following silver nanoparticles (AgNPs; 80 mg/kg; >100 nm) intoxication in male rats.

Results

AgNPs-intoxication elevated the liver function markers – including serum transaminases and alkaline phosphatase activities – and decreased serum levels of albumin and total proteins, in addition to disturbing the oxidation homeostasis. This is evidenced by the increased lipid peroxidation, the depleted glutathione, and the suppressed activity of superoxide dismutase and catalase. In addition, an apoptotic reaction was observed following AgNPs treatment, as indicated by the up-regulation of p53 and down-regulating Bcl-2 expressions, examined by the immunohistochemistry method. Furthermore, AgNPs exhibited a marked elevation in liver DNA damage that was indicated by an increase in tail length, tail DNA% and tail movement. However, BWE eliminated the biochemical and histological alterations, reflecting its hepatoprotection effect in response to AgNPs.

Discussion

Collectively, the present data suggest that BWE could be used following AgNPs as a potential therapeutic intervention to minimize AgNPs-induced liver toxicity.

SilverSil: A New Class of Antibacterial Materials of Broad Scope

Consisting of organically modified silica (ORMOSIL) physically doped with Ag nanoparticles, the SilverSil new class of antibacterial materials of broad scope reported herein shows remarkably high and stable activity against representative Gram-positive and Gram-negative bacteria. The low cost, ease of application and excellent health and environmental profile of SilverSil hybrid glassy coatings open the route to their widespread utilization across domestic, hospital, school, industrial and commercial environments and in consumer products.

The Hemocompatibility of Nanoparticles: A Review of Cell-Nanoparticle Interactions and Hemostasis

Understanding cell-nanoparticle interactions is critical to developing effective nanosized drug delivery systems. Nanoparticles have already advanced the treatment of several challenging conditions including cancer and human immunodeficiency virus (HIV), yet still hold the potential to improve drug delivery to elusive target sites. Even though most nanoparticles will encounter blood at a certain stage of their transport through the body, the interactions between nanoparticles and blood cells is still poorly understood and the importance of evaluating nanoparticle hemocompatibility is vastly understated. In contrast to most review articles that look at the interference of nanoparticles with the intricate coagulation cascade, this review will explore nanoparticle hemocompatibility from a cellular angle. The most important functions of the three cellular components of blood, namely erythrocytes, platelets and leukocytes, in hemostasis are highlighted. The potential deleterious effects that nanoparticles can have on these cells are discussed and insight is provided into some of the complex mechanisms involved in nanoparticle-blood cell interactions. Throughout the review, emphasis is placed on the importance of undertaking thorough, all-inclusive hemocompatibility studies on newly engineered nanoparticles to facilitate their translation into clinical application.

High Bactericidal Self-Assembled Nano-Monolayer of Silver Sulfadiazine on Hydroxylated Material Surfaces

Anti-infective surfaces are a modern strategy to address the issue of infection related to the clinical use of materials for implants and medical devices. Nanocoatings, with their high surface/mass ratio, lend themselves to being mono-layered on the material surfaces to release antibacterial molecules and prevent bacterial adhesion. Here, a “layer-by-layer” (LbL) approach to achieve a self-assembled monolayer (SAM) with high microbicidal effect on hydroxylated surfaces is presented, exploiting the reaction between a monolayer of thiolic functions on glass/quartz surfaces and a newly synthesized derivative of the well-known antibacterial compound silver sulfadiazine. Using several different techniques, it is demonstrated that a nano-monolayer of silver sulfadiazine is formed on the surfaces. The surface-functionalized materials showed efficient bactericidal effect against both Gram-positive and Gram-negative bacteria. Interestingly, bactericidal self-assembled nano-monolayers of silver sulfadiazine could be achieved on a large variety of materials by simply pre-depositing glass-like SiO₂ films on their surfaces.

Stranded false killer whales, Pseudorca crassidens, in Southern South America reveal potentially dangerous silver concentrations

Silver (Ag) is a non-essential metal known to bioaccumulate in aquatic organisms. We determined Ag concentrations in five false killer whales stranded in South America. Silver concentrations (in dry weight basis) range as 6.62-10.78 μg g^-1 in liver, 0.008-7.41 μg g^-1 in spleen, 0.004-5.71 μg g^-1 in testis, 0.757-1.69 μg g^-1 in kidney, 0.011-0.078 μg g^-1 in lung and < 0.01-0.038 μg g^-1 in muscle, whereas in the single samples of uterus and ovary were 0.051 and 0.023 μg g^-1; respectively. Overall, Ag concentration in liver and kidney exceeded the cetacean toxic thresholds, proposed as "unhealthy concentrations" and "critically dangerous" in liver and kidney. These results warrant further eco-toxicological studies, to examine biological effects of elevated silver levels for individuals and to assess the species' conservation status with respect to marine pollution.

Use of Autometallography to Localize and Semi-Quantify Silver in Cetacean Tissues

Silver nanoparticles (AgNPs) have been extensively used in commercial products, including textiles, cosmetics, and health care items, due to their strong antimicrobial effects. They also may be released into the environment and accumulate in the ocean. Therefore, AgNPs are the major source of Ag contamination, and public awareness of the environmental toxicity of Ag is increasing. Previous studies have demonstrated the bioaccumulation (in producers) and magnification (in consumers/predators) of Ag. Cetaceans, as the apex predators of ocean, may have been negatively affected by the Ag/Ag compounds. Although the concentrations of Ag/Ag compounds in cetacean tissues can be measured by inductively coupled plasma mass spectroscopy (ICP-MS), the use of ICP-MS is limited by its high capital cost and the requirement for tissue storage/preparation. Therefore, an autometallography (AMG) method with an image quantitative analysis by using formalin-fixed, paraffin-embedded (FFPE) tissue may be an adjuvant method to localize Ag distribution at the suborgan level and estimate the Ag concentration in cetacean tissues. The AMG positive signals are mainly brown to black granules of various sizes in the cytoplasm of proximal renal tubular epithelium, hepatocytes, and Kupffer cells. Occasionally, some amorphous golden yellow to brown AMG positive signals are noted in the lumen and basement membrane of some proximal renal tubules. The assay for estimating the Ag concentration is named the Cetacean Histological Ag Assay (CHAA), which is a regression model established by the data from image quantitative analysis of the AMG method and ICP-MS. The use of AMG with CHAA to localize and semi-quantify heavy metals provides a convenient methodology for spatio-temporal and cross-species studies.

Th2 cytokine bias induced by silver nanoparticles in peripheral blood mononuclear cells of common bottlenose dolphins (Tursiops truncatus)

BACKGROUND

Silver nanoparticles (AgNPs) have been widely used in many commercial products due to their excellent antibacterial ability. The AgNPs are released into the environment, gradually accumulate in the ocean, and may affect animals at high trophic levels, such as cetaceans and humans, via the food chain. Hence, the negative health impacts caused by AgNPs in cetaceans are of concern. Cytokines play a major role in the modulation of immune system and can be classified into two types: Th1 and Th2. Th1/Th2 balance can be evaluated by the ratios of their polarizing cytokines (i.e., interferon [IFN]-γ/Interleukin [IL]-4), and animals with imbalanced Th1/Th2 response may become more susceptible to certain kinds of infection. Therefore, the present study evaluated the in vitro cytokine responses of cetacean peripheral blood mononuclear cells (cPBMCs) to 20 nm citrate-AgNPs (C-AgNP20) by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR).

METHODS

Blood samples were collected from six captive common bottlenose dolphins (Tursiops truncatus). The cPBMCs were isolated and utilized for evaluating the in vitro cytokine responses. The cytokines evaluated included IL-2, IL-4, IL-10, IL-12, interferon (IFN)-γ, and tumor necrosis factor (TNF)-α. The geometric means of two housekeeping genes (HKGs), glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and β2-microglobulin (B2M), of each sample were determined and used to normalize the mRNA expression levels of target genes.

RESULTS

The ratio of late apoptotic/necrotic cells of cPBMCs significantly increased with or without concanavalin A (ConA) stimulation after 24 h of 10 µg/ml C-AgNP20 treatment. At 4 h of culture, the mRNA expression level of IL-10 was significantly decreased with 1 µg/ml C-AgNP20 treatment. At 24 h of culture with 1 µg/ml C-AgNP20, the mRNA expression levels of all cytokines were significantly decreased, with the exceptions of IL-4 and IL-10. The IFN-γ/IL-4 ratio was significantly decreased at 24 h of culture with 1 µg/ml C-AgNP20 treatment, and the IL-12/IL-4 ratio was significantly decreased at 4 or 24 h of culture with 0.1 or 1 µg/ml C-AgNP20 treatment, respectively. Furthermore, the mRNA expression level of TNF-α was significantly decreased by 1 µg/ml C-AgNP20 after 24 h of culture.

DISCUSSION

The present study demonstrated that the sublethal dose of C-AgNP20 (≤1 µg/ml) had an inhibitory effect on the cytokine mRNA expression levels of cPBMCs with the evidence of Th2 cytokine bias and significantly decreased the mRNA expression level of TNF-α. Th2 cytokine bias is associated with enhanced immunity against parasites but decreased immunity to intracellular microorganisms. TNF-α is a contributing factor for the inflammatory response against the infection of intracellular pathogens. In summary, our data indicate that C-AgNP20 suppresses the cellular immune response and thereby increases the susceptibility of cetaceans to infection by intracellular microorganisms.