Zinc Oxide Nanoparticles Influence Microflora in Ileal Digesta and Correlate Well with Blood Metabolites

Does the dietary supplementation of organic nano-zinc as a growth promoter impact broiler's growth, carcass and meat quality traits, blood metabolites and cecal microbiota?

The present investigation aimed to examine the impact of different dietary organic zinc nanoparticle (ZnNP) levels on gut bacteria, meat quality, growth performance, carcass traits, and blood indicators of broilers. A total of 180 unsexed one-wk broiler chicks (Cobb) were allotted to 3 experimental groups and received a basal diet supplemented with 0, 0.2, and 0.4 mg ZnNPs/Kg diet, respectively. The results showed that, after 38 d of age, the supplementary ZnNPs at a level of 0.4 mg/kg raised body weight and weight gain compared to the control and 0.2 mg ZnNPs/kg diet. The addition of ZnNPs improved the daily feed intake. Some of the carcass characteristics in ZnNPs groups excelled that of the control. ZnNPs treatments gave higher dressing % and decreased (P < 0.05) the cholesterol rates, LDL, and uric acid in the blood. In addition, it gave the best concentrations of ALT and AST. The ZnNPs groups exhibited substantially (P < 0.05) improved moisture and fat values in meat samples. The group given ZnNPs at a concentration of 0.4 mg/kg had a substantially (P < 0.05) lower count of TYMC and E. coli. In conclusion, the high level of ZnNPs (0.4 mg/kg) improved the broilers' performance and some of their carcass traits, enhancing their health and meat quality.

Nanoparticles incorporated hydrogels for delivery of antimicrobial agents: developments and trends

The prevention and treatment of microbial infections is an imminent global public health concern due to the poor antimicrobial performance of the existing antimicrobial regime and rapidly emerging antibiotic resistance in pathogenic microbes. In order to overcome these problems and effectively control bacterial infections, various new treatment modalities have been identified. To attempt this, various micro- and macro-molecular antimicrobial agents that function by microbial membrane disruption have been developed with improved antimicrobial activity and lesser resistance. Antimicrobial nanoparticle-hydrogels systems comprising antimicrobial agents (antibiotics, biological extracts, and antimicrobial peptides) loaded nanoparticles or antimicrobial nanoparticles (metal or metal oxide) constitute an important class of biomaterials for the prevention and treatment of infections. Hydrogels that incorporate nanoparticles can offer an effective strategy for delivering antimicrobial agents (or nanoparticles) in a controlled, sustained, and targeted manner. In this review, we have described an overview of recent advancements in nanoparticle-hydrogel hybrid systems for antimicrobial agent delivery. Firstly, we have provided an overview of the nanoparticle hydrogel system and discussed various advantages of these systems in biomedical and pharmaceutical applications. Thereafter, different hybrid hydrogel systems encapsulating antibacterial metal/metal oxide nanoparticles, polymeric nanoparticles, antibiotics, biological extracts, and antimicrobial peptides for controlling infections have been reviewed in detail. Finally, the challenges and future prospects of nanoparticle-hydrogel systems have been discussed.

Oxidative stress and potential effects of metal nanoparticles: A review of biocompatibility and toxicity concerns

Metal nanoparticles (M-NPs) have garnered significant attention due to their unique properties, driving diverse applications across packaging, biomedicine, electronics, and environmental remediation. However, the potential health risks associated with M-NPs must not be disregarded. M-NPs' ability to accumulate in organs and traverse the blood-brain barrier poses potential health threats to animals, humans, and the environment. The interaction between M-NPs and various cellular components, including DNA, multiple proteins, and mitochondria, triggers the production of reactive oxygen species (ROS), influencing several cellular activities. These interactions have been linked to various effects, such as protein alterations, the buildup of M-NPs in the Golgi apparatus, heightened lysosomal hydrolases, mitochondrial dysfunction, apoptosis, cell membrane impairment, cytoplasmic disruption, and fluctuations in ATP levels. Despite the evident advantages M-NPs offer in diverse applications, gaps in understanding their biocompatibility and toxicity necessitate further research. This review provides an updated assessment of M-NPs' pros and cons across different applications, emphasizing associated hazards and potential toxicity. To ensure the responsible and safe use of M-NPs, comprehensive research is conducted to fully grasp the potential impact of these nanoparticles on both human health and the environment. By delving into their intricate interactions with biological systems, we can navigate the delicate balance between harnessing the benefits of M-NPs and minimizing potential risks. Further exploration will pave the way for informed decision-making, leading to the conscientious development of these nanomaterials and safeguarding the well-being of society and the environment.

Zinc Oxide Nanoparticles Significant Role in Poultry and Novel Toxicological Mechanisms

Zinc oxide nanoparticles (ZnO NPs) have involved a lot of consideration owing to their distinctive features. The ZnO NPs can be described as particularly synthesized mineral salts via nanotechnology, varying in size from 1 to 100 nm, while zinc oxide (ZnO), it is an inorganic substrate of zinc (Zn). The Zn is a critical trace element necessary for various biological and physiological processes in the body. Studies have revealed ZnO NPs' efficient immuno-modulatory, growth-promoting, and antimicrobial properties in poultry birds. They offer increased bioavailability as compared to their traditional sources, producing better results in terms of productivity and welfare and consequently reducing ecological harm in the poultry sector. However, they have also been reported for their toxicological effects, which are size, shape, concentration, and exposure route dependent. The investigations done so far have yielded inconsistent results, therefore, a lot of additional studies and research are required to clarify the harmful consequences of ZnO NPs and to bring them to a logical end. This review explores an overview of efficient possible role of ZnO NPs, while comparing them with other nutritional Zn sources, in the poultry industry, primarily as dietary supplements that effect the growth, health, and performance of the birds. In addition to the anti-bacterial mechanisms of ZnO NPs and their promising role as antifungal, and anti-colloidal agent, this paper also covers the toxicological mechanisms of ZnO NPs and their consequent toxicological hazards to vital organs and the reproductive system of poultry birds.

Paeoniflorin recued hepatotoxicity under zinc oxide nanoparticles exposure via regulation on gut-liver axis and reversal of pyroptosis

The risks of Zinc oxide nanoparticles (ZnO NPs) applications in biological medicine, food processing industry, agricultural production and the biotoxicity brought by environmental invasion of ZnO NPs both gradually troubled the public due to the lack of research on detoxification strategies. TFEB-regulated autophagy-pyroptosis pathways were found as the crux of the hepatotoxicity induced by ZnO NPs in our latest study. Here, our study served as a connecting link between preceding toxic target and the following protection mechanism of Paeoniflorin (PF). According to a combined analysis of network pharmacology/molecular docking-intestinal microbiota-metabolomics first developed in our study, PF alleviated the hepatotoxicity of ZnO NPs from multiple aspects. The hepatic inflammatory injury and hepatocyte pyroptosis in mice liver exposed to ZnO NPs was significantly inhibited by PF. And the intestinal microbiota disorder and liver metabolic disturbance were rescued. The targets predicted by bioinformatics and the signal trend in subacute toxicological model exhibited the protectiveness of PF related to the SIRT1-mTOR-TFEB pathway. These evidences clarified multiple protective mechanisms of PF which provided a novel detoxification approach against ZnO NPs, and further provided a strategy for the medicinal value development of PF.

Influence of heavy metal exposure on gut microbiota: Recent advances

Gut microbiota plays a functionally important part in retaining the homeostasis of host physiology, however, under exposure of various heavy metals, the composition of gut biota is disturbed in relation to species diversity and richness. Ever since the increase of microbiome-related studies during the last decade, many research studies have delivered an understanding of the reasons and concerns of gut microbiota-related modifications. During the past decade, it's been confirmed from various studies that heavy metals poisoning alters the microbial composition, which results in changes in gene expression, alteration in metabolism, immunity, neurological dysfunction, and causes various other disorders. The present comprehensive review is summarizing an attempt to enumerate the key findings from recent clinical or preclinical studies related to the influence of heavy metals on gut microbiota published recently. Google, PubMed, Science Direct, Scopus, and Google Scholar were employed as primary search engines using the keywords such as "heavy metals, gut microbiota, dysbiosis, and intestinal microbiota" for finding relevant research articles from the past 10 years and some old important articles. Here, we tried to provide insight into some of the key timelines and scientific findings from reported literature, like the effects of heavy metals such as arsenic, cadmium, lead, and mercury on the general body and specifically on the gut microbiota of different model organisms. So, it is important to increase awareness against heavy metal-induced toxicity and formulate guidelines for the benefit of the environment.

Effect of Nanomaterials on Gut Microbiota

Nanomaterials are widely employed in everyday life, including food and engineering. Food additives on a nanoscale can enter the body via the digestive tract. The human gut microbiota is a dynamically balanced ecosystem composed of a multitude of microorganisms that play a crucial role in maintaining the proper physiological function of the digestive tract and the body's endocrine coordination. While the antibacterial capabilities of nanomaterials have received much interest in recent years, their impacts on gut microbiota ought to be cautioned about and explored. Nanomaterials exhibit good antibacterial capabilities in vitro. Animal studies have revealed that oral exposure to nanomaterials inhibits probiotic reproduction, stimulates the inflammatory response of the gut immune system, increases opportunistic infections, and changes the composition and structure of the gut microbiota. This article provides an overview of the impacts of nanomaterials, particularly titanium dioxide nanoparticles (TiO₂ NPs), on the gut microbiota. It advances nanomaterial safety research and offers a scientific foundation for the prevention, control, and treatment of illnesses associated with gut microbiota abnormalities.

Heat transfer analysis of fractional model of couple stress Casson tri-hybrid nanofluid using dissimilar shape nanoparticles in blood with biomedical applications

During last decades the research of nanofluid is of great interest all over the World, particularly because of its thermal applications in engineering, and biological sciences. Although nanofluid performance is well appreciate and showed good results in the heat transport phenomena, to further improve conventional base fluids thermal performance an increasing number of researchers have started considering structured nanoparticles suspension in one base fluid. As to make an example, when considering the suspension of three different nanoparticles in a single base fluid we have the so called "ternary hybrid nanofluid". In the present study three different shaped nanoparticles are uniformly dispersed in blood. In particular, the three different shaped nanoparticles are spherical shaped ferric oxide [Formula: see text], platelet shaped zinc [Formula: see text], and cylindrical shaped gold [Formula: see text], which are considered in blood base fluid because of related advance pharmaceutical applications. Accordingly, we focused our attention on the sharp evaluation of heat transfer for the unsteady couple stress Casson tri-hybrid nanofluid flow in channel. In particular, we formulated the problem via momentum and energy equations in terms of partial differential equations equipped with realistic physical initial and boundary conditions. Moreover, we transformed classical model into their fractional counterparts by applying the Atangana-Baleanu time-fractional operator. Solutions to velocity and temperature equations have been obtained by using both the Laplace and the Fourier transforms, while the effect of physical parameters on velocity and temperature profiles, have been graphically analyzed exploiting MATHCAD. In particular, latter study clearly shows that for higher values of volume fraction [Formula: see text] of the nanoparticles the fluid velocity declines, while the temperature rises for the higher values of volume fraction [Formula: see text] of the nanoparticles. Using blood-based ternary hybrid nanofluid enhances the rate of heat transfer up-to 8.05%, spherical shaped [Formula: see text] enhances up-to 4.63%, platelet shaped [Formula: see text] nanoparticles enhances up-to 8.984% and cylindrical shaped gold [Formula: see text] nanoparticles enhances up-to 10.407%.

Metallic Nanosystems in the Development of Antimicrobial Strategies with High Antimicrobial Activity and High Biocompatibility

Antimicrobial resistance is a major and growing global problem and new approaches to combat infections caused by antibiotic resistant bacterial strains are needed. In recent years, increasing attention has been paid to nanomedicine, which has great potential in the development of controlled systems for delivering drugs to specific sites and targeting specific cells, such as pathogenic microbes. There is continued interest in metallic nanoparticles and nanosystems based on metallic nanoparticles containing antimicrobial agents attached to their surface (core shell nanosystems), which offer unique properties, such as the ability to overcome microbial resistance, enhancing antimicrobial activity against both planktonic and biofilm embedded microorganisms, reducing cell toxicity and the possibility of reducing the dosage of antimicrobials. The current review presents the synergistic interactions within metallic nanoparticles by functionalizing their surface with appropriate agents, defining the core structure of metallic nanoparticles and their use in combination therapy to fight infections. Various approaches to modulate the biocompatibility of metallic nanoparticles to control their toxicity in future medical applications are also discussed, as well as their ability to induce resistance and their effects on the host microbiome.

Advanced Hydrogels Combined with Silver and Gold Nanoparticles against Antimicrobial Resistance

The development of multidrug-resistant (MDR) microorganisms has increased dramatically in the last decade as a natural consequence of the misuse and overuse of antimicrobials. The World Health Organization (WHO) recognizes that this is one of the top ten global public health threats facing humanity today, demanding urgent multisectoral action. The UK government foresees that bacterial antimicrobial resistance (AMR) could kill 10 million people per year by 2050 worldwide. In this sense, metallic nanoparticles (NPs) have emerged as promising alternatives due to their outstanding antibacterial and antibiofilm properties. The efficient delivery of the NPs is also a matter of concern, and recent studies have demonstrated that hydrogels present an excellent ability to perform this task. The porous hydrogel structure with a high-water retention capability is a convenient host for the incorporation of the metallic nanoparticles, providing an efficient path to deliver the NPs properly reducing bacterial infections caused by MDR pathogenic microorganisms. This article reviews the most recent investigations on the characteristics, applications, advantages, and limitations of hydrogels combined with metallic NPs for treating MDR bacteria. The mechanisms of action and the antibiofilm activity of the NPs incorporated into hydrogels are also described. Finally, this contribution intends to fill some gaps in nanomedicine and serve as a guide for the development of advanced medical products.

NMR-Based Metabolomics to Decipher the Molecular Mechanisms in the Action of Gut-Modulating Foods

Metabolomics deals with uncovering and characterizing metabolites present in a biological system, and is a leading omics discipline as it provides the nearest link to the biological phenotype. Within food and nutrition, metabolomics applied to fecal samples and bio-fluids has become an important tool to obtain insight into how food and food components may exert gut-modulating effects. This review aims to highlight how nuclear magnetic resonance (NMR)-based metabolomics in food and nutrition science may help us get beyond where we are today in understanding foods’ inherent, or added, biofunctionalities in relation to gut health.

Modulation of Gut Microbiota by Essential Oils and Inorganic Nanoparticles: Impact in Nutrition and Health

Microbiota plays a crucial role in human health and disease; therefore, the modulation of this complex and yet widely unexplored ecosystem is a biomedical priority. Numerous antibacterial alternatives have been developed in recent years, imposed by the huge problem of antibioresistance, but also by the people demand for natural therapeutical products without side effects, as dysbiosis, cyto/hepatotoxicity. Current studies are focusing mainly in the development of nanoparticles (NPs) functionalized with herbal and fruit essential oils (EOs) to fight resistant pathogens. This is due to their increased efficiency against susceptible, multidrug resistant and biofilm embedded microorganisms. They are also studied because of their versatile properties, size and possibility to ensure a targeted administration and a controlled release of bioactive substances. Accordingly, an increasing number of studies addressing the effects of functional nanoparticles and plant products on microbial pathogens has been observed. Regardless the beneficial role of EOs and NPs in the treatment of infectious diseases, concerns regarding their potential activity against human microbiota raised constantly in recent years. The main focus of current research is on gut microbiota (GM) due to well documented metabolic and immunological functions of gut microbes. Moreover, GM is constantly exposed to micro- and nano-particles, but also plant products (including EOs). Because of the great diversity of both microbiota and chemical antimicrobial alternatives (i.e., nanomaterials and EOs), here we limit our discussion on the interactions of gut microbiota, inorganic NPs and EOs. Impact of accidental exposure caused by ingestion of day care products, foods, atmospheric particles and drugs containing nanoparticles and/or fruit EOs on gut dysbiosis and associated diseases is also dissected in this paper. Current models developed to investigate mechanisms of dysbiosis after exposure to NPs/EOs and perspectives for identifying factors driving EOs functionalized NPs dysbiosis are reviewed.

Dietary exposure of copper and zinc oxides nanoparticles affect the fitness, enzyme activity, and microbial community of the model insect, silkworm Bombyx mori

Copper and Zinc oxides nanoparticles (CuO and ZnO NPs, respectively) are among the most produced and commonly used engineered nanomaterials. They can be released into the environment, thereby causing health concerns and risks to biodiversity that indicate a need to evaluate their toxicological effects in a complex situation. Here, we used the insect model organism silkworm Bombyx mori to address the concerns about the biological effects associated with dietary exposure of CuO and ZnO NPs. ICP-MS analysis revealed significant accumulation of Cu and Zn (the latter being more accumulated) in silkworms' tissues (gut, fat body, silk gland, and malpighian tubule), and some elimination through feces in the respective NPs-exposed groups. NPs-exposures led to a decrease in larval body mass, survivorship, and cocoon production, where the effects of ZnO NPs were more pronounced. We also found that NPs-exposure induced gene expression changes (Attacin, lysozyme, SOD, and Dronc) and altered the activities of antioxidant enzymes (SOD, GST, and CAT), as well as impaired nutrient metabolism (alpha-amylase). Given their antibacterial property, CuO and ZnO NPs decreased species richness and diversity of the gut bacterial community and shifted their configuration to overt microbiome i.e., decreased abundance of probiotics (e.g., Acetobacter) and increased pathobionts (e.g., Pseudomonas, Bacillus, Escherichia, Enterococcus, Ralstonia, etc.) proportions. Overall, this integrated study revealed the unintended negative effects of CuO and ZnO NPs on silkworms and highlighted the potential to inevitably affect all living things due to intensive and possible mishandling of nanomaterials.

A systematic review on the effects of nanomaterials on gut microbiota

Some nanomaterials (NMs) have been shown to possess antimicrobial activity and cause GM dysbiosis. Since NMs are being used widely, a systematic assessment of the effects of NMs on GM is warranted. In this systematic review, a total of 46 in vivo and 22 in vitro studies were retrieved from databases and search engines including Science-Direct, Pubmed and Google scholar. Criteria for assessment of studies included use of in vitro or in vivo studies, characterization of NMs, use of single or multiple doses as well as consistency of results. GM dysbiosis has been studied most widely on TiO2, Ag, Zn-based NMs. There was moderate evidence for GM dysbiosis caused by Zn- and Cu-based NMs, Cu-loaded chitosan NPs and Ag NMs, and anatase TiO2 NPs, as well as low evidence for SWCNTs, nanocellulose, SiO2, Se, nanoplastics, CeO2, MoO3 and graphene-based NMs. Most studies indicate adverse effects of NMs towards GM. However, more work is required to elucidate the differences on the reported effects of NM by type and sex of organisms, size, shape and surface properties of NMs as well as effects of exposure to mixtures of NMs. For consistency and better agreement among studies on GM dysbiosis, there is need for internationally agreed protocols on, inter alia, characterization of NMs, dosing (amounts, frequency and duration), use of sonication, test systems (both in vitro and in vivo), including oxygen levels for in vitro models.

Nanoparticle Food Applications and Their Toxicity: Current Trends and Needs in Risk Assessment Strategies

ABSTRACT

Nanotechnology has developed into one of the most groundbreaking scientific fields in the last few decades because it exploits the enhanced reactivity of materials at the atomic scale. The current classification of nanoparticles (NPs) used in foods is outlined in relation to the production and physicochemical characteristics. This review aims to concisely present the most popular and widely used inorganic and organic NPs in food industries. Considering that the toxicity of NPs is often associated with chemical reactivity, a series of in vitro toxicity studies are also summarized, integrating information on the type of NP studies and reported specifications, type of cells used, exposure conditions, and assessed end points. The important role of the digestive system in the absorption and distribution of nanoformulated foods within the body and how this affects the resultant cytotoxicity. Examples of how NPs and their accumulation within different organs are presented in relation to the consumption of specific foods. Finally, the role of developing human health risk assessments to characterize both the potential impact of the hazard and the likelihood or level of human exposure is outlined. Uncertainties exist around risk and exposure assessments of NPs due to limited information on several aspects, including toxicity, behavior, and bioaccumulation. Overall, this review presents current trends and needs for future assessments in toxicity evaluation to ensure the safe application of NPs in the food industry.

HIGHLIGHTS

Synergistic effect of ZnO NPs and imidacloprid on liver injury in male ICR mice: Increase the bioavailability of IMI by targeting the gut microbiota

Although many toxicological studies on pesticides and nanoparticles have been conducted, it is not clear whether nanoparticles will increase the toxicity of pesticides. In this study, we chose imidacloprid (IMI) as a representative pesticide, and explored the influence of ZnO NPs on the toxic effect of IMI. In addition, we studied the bioaccumulation of IMI in mice. Using biochemical index analysis, liver histopathological analysis, non-targeted metabolomics, and LC/MS analysis, we found that ZnO NPs increased the toxicity of IMI, which may be related to the increase in IMI bioaccumulation in mice. In addition, we used intestinal histopathological analysis, RT-qPCR, and 16sRNA sequencing to find that the disturbance of the gut microbiota and the impaired intestinal barrier caused by ZnO NPs may be the reason for the increase in IMI bioaccumulation. In summary, our results indicate that ZnO NPs disrupted the intestinal barrier and enhanced the bioaccumulation of IMI, and therefore increased the toxicity of IMI in mice. Our research has deepened the toxicological insights between nanomaterials and pesticides.

Food Additives, a Key Environmental Factor in the Development of IBD through Gut Dysbiosis

Diet is a key environmental factor in inflammatory bowel disease (IBD) and, at the same time, represents one of the most promising therapies for IBD. Our daily diet often contains food additives present in numerous processed foods and even in dietary supplements. Recently, researchers and national authorities have been paying much attention to their toxicity and effects on gut microbiota and health. This review aims to gather the latest data focusing on the potential role of food additives in the pathogenesis of IBDs through gut microbiota modulation. Some artificial emulsifiers and sweeteners can induce the dysbiosis associated with an alteration of the intestinal barrier, an activation of chronic inflammation, and abnormal immune response accelerating the onset of IBD. Even if most of these results are retrieved from in vivo and in vitro studies, many artificial food additives can represent a potential hidden driver of gut chronic inflammation through gut microbiota alterations, especially in a population with IBD predisposition. In this context, pending the confirmation of these results by large human studies, it would be advisable that IBD patients avoid the consumption of processed food containing artificial food additives and follow a personalized nutritional therapy prescribed by a clinical nutritionist.

Chestnut polysaccharides restore impaired spermatogenesis by adjusting gut microbiota and the intestinal structure

Our previous study confirmed the beneficial effects of chestnut polysaccharides (CPs) on the spermatogenesis process, but the exact mechanism is not clear. Several studies have demonstrated the importance of balanced gut microbiota in maintaining normal reproductive function. In this study, we investigated the biological functions of CPs from the perspective of gut microbiota function, expecting to find out the specific mechanism of CPs in restoring impaired spermatogenesis. Compared with the control group, the mice treated with busulfan showed a reduced number of germ cells, structural changes in the small intestine and composition alteration in the gut microbiota at several levels, including the phylum and genus. In contrast, the number of germ cells in seminiferous tubules was significantly increased, and the structure of the small intestine and the composition of the gut microbiota were altered in the busulfan-treated mice after the CPs treatment. The 16s rRNA analysis results showed that the Firmicutes was the predominant phylum in all groups followed by Proteobacteria, Bacteroidetes, Actinobacteria, Tenericutes, Cyanobacteria and unidentified bacteria. Interestingly, the subsequent functional analysis implied that the steroid hormone biosynthesis process is the major metabolic pathway in the CPs-mediated restoration process and the experimental results confirmed this speculation. In conclusion, this study confirmed that CPs can restore the impaired spermatogenesis process by adjusting the gut microbiota and intestinal structure, which will also provide technical support and a theoretical basis for the subsequent treatment of male infertility.

Impact of nanomaterials on the intestinal mucosal barrier and its application in treating intestinal diseases

The intestinal mucosal barrier (IMB) is one of the important barriers to prevent harmful substances and pathogens from entering the body environment and to maintain intestinal homeostasis. The dysfunction of the IMB is associated with intestinal diseases and disorders. Nanomaterials have been widely used in medicine and as drug carriers due to their large specific surface area, strong adsorbability, and good biocompatibility. In this review, we comprehensively discuss the impact of typical nanomaterials on the IMB and summarize the treatment of intestinal diseases by using nanomaterials. The effects of nanomaterials on the IMB are mainly influenced by factors such as the dosage, size, morphology, and surface functional groups of nanomaterials. There is huge potential and a broad prospect for the application of nanomaterials in regulating the IMB for achieving an optimal therapeutic effect for antibiotics, oral vaccines, drug carriers, and so on.

Antibacterial Potential of Biosynthesized Zinc Oxide Nanoparticles against Poultry-Associated Foodborne Pathogens: An In Vitro Study

Simple Summary

The overuse of antibiotics in the poultry industry has led to the emergence of multidrug-resistant microorganisms. Thus, there is a need to find an alternative to conventional antibiotics. Recently, zinc oxide nanoparticles (ZnO NPs) have gained much attention due to their excellent antibacterial activity. In addition, ZnO NPs is an essential trace mineral in poultry diets. In this sense, incorporating ZnO NPs into poultry can promote growth and performance while serving as an alternative antibacterial agent to control diseases. Therefore, this study aimed to assess the in vitro antibacterial activity and antibacterial mechanisms of ZnO NPs against poultry-associated foodborne pathogens (Salmonella spp., Escherichia coli, and Staphylococcus aureus). The obtained findings demonstrated effective antibacterial actions against the tested microorganisms. The nanotechnology approach could represent a new tool for combating pathogens in the poultry industry.

Abstract

Since the emergence of multidrug-resistant bacteria in the poultry industry is currently a serious threat, there is an urgent need to develop a more efficient and alternative antibacterial substance. Zinc oxide nanoparticles (ZnO NPs) have exhibited antibacterial efficacy against a wide range of microorganisms. Although the in vitro antibacterial activity of ZnO NPs has been studied, little is known about the antibacterial mechanisms of ZnO NPs against poultry-associated foodborne pathogens. In the present study, ZnO NPs were successfully synthesized using Lactobacillus plantarum TA4, characterized, and their antibacterial potential against common avian pathogens (Salmonella spp., Escherichia coli, and Staphylococcus aureus) was investigated. Confirmation of ZnO NPs by UV-Visual spectroscopy showed an absorption band center at 360 nm. Morphologically, the synthesized ZnO NPs were oval with an average particle size of 29.7 nm. Based on the dissolution study of Zn²⁺, ZnO NPs released more ions than their bulk counterparts. Results from the agar well diffusion assay indicated that ZnO NPs effectively inhibited the growth of the three poultry-associated foodborne pathogens. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were assessed using various concentrations of ZnO NPs, which resulted in excellent antibacterial activity as compared to their bulkier counterparts. S. aureus was more susceptible to ZnO NPs compared to the other tested bacteria. Furthermore, the ZnO NPs demonstrated substantial biofilm inhibition and eradication. The formation of reactive oxygen species (ROS) and cellular material leakage was quantified to determine the underlying antibacterial mechanisms, whereas a scanning electron microscope (SEM) was used to examine the morphological changes of tested bacteria treated with ZnO NPs. The findings suggested that ROS-induced oxidative stress caused membrane damage and bacterial cell death. Overall, the results demonstrated that ZnO NPs could be developed as an alternative antibiotic in poultry production and revealed new possibilities in combating pathogenic microorganisms.

Intestinal digestibility of selected minerals, growth performance and meat quality in turkeys fed diets supplemented with different sources and levels of zinc

The aim of this study was to determine whether dietary supplementation with zinc oxide nanoparticales (NP-ZnO) as a substitute for the conventional ZnO affects the intestinal digestibility of selected minerals, growth performance and meat quality in turkeys. The replacement of ZnO with NP-ZnO had no effect on the intestinal digestibility of Zn, Cu, Fe and Ca, whereas the lowest dose of supplemental Zn reduced Zn digestibility. The applied inclusion levels and sources of Zn had no effect on the growth performance (except the feed intake) of turkeys, including liveability. No differences in the relative weights of the heart, spleen and bursa of Fabricius (except the liver), or the weights of the femur and tibia were found between the dietary treatments. Neither the dose nor the source of supplemental Zn influenced carcass dressing percentage or the share of breast, thigh and drumstick muscles in the carcass. In comparison with the highest and moderate doses of Zn, the lowest inclusion level of Zn contributed to increased yellowness of breast meat (P=0.005). The analyzed doses and sources of supplemental Zn exerted varied effects on the redox status of fresh and frozen breast meat. In conclusion, the growth performance of turkeys, carcass yield and composition as well as the redox status of fresh and frozen breast meat were generally similar, regardless of the dietary source and level of Zn. The beneficial effect of Zn addition at 100 mg/kg was improved Zn and Ca digestibility, and increased redness of breast meat.

A review: non-antibacterial, non-antifungal and non-anticancer properties of nanoparticles the forgotten paradigm

The review highlights the need of non-antibacterial, non-antifungal and non-anticancer characters of metal or metal oxide nanoparticles. The usage of nanoparticles as a part of therapeutic measures results in certain unfavourable effects. The nanoparticles can disturb healthy gut microorganisms that may bring about some health damages regarding pathogenic diseases, obesity, and inflammation likewise. Even the nonspecific interactions of nanoparticles with healthy cells and tissues can cause altered expressions of various pro-inflammatory factors and stress related genes. This review indicates and prospect about the demand of nanoparticles with non-antibacterial, non-antifungal and non-anticancer properties. Such nanoparticles will be effective in various remedial and diagnostic purposes.

Nanoparticles in the Food Industry and Their Impact on Human Gut Microbiome and Diseases

The use of inorganic nanoparticles (NPs) has expanded into various industries including food manufacturing, agriculture, cosmetics, and construction. This has allowed NPs access to the human gastrointestinal tract, yet little is known about how they may impact human health. As the gut microbiome continues to be increasingly implicated in various diseases of unknown etiology, researchers have begun studying the potentially toxic effects of these NPs on the gut microbiome. Unfortunately, conflicting results have limited researcher’s ability to evaluate the true impact of NPs on the gut microbiome in relation to health. This review focuses on the impact of five inorganic NPs (silver, iron oxide, zinc oxide, titanium dioxide, and silicon dioxide) on the gut microbiome and gastrointestinal tract with consideration for various methodological differences within the literature. This is important as NP-induced changes to the gut could lead to various gut-related diseases. These include irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), celiac disease, and colorectal cancer. Research in this area is necessary as the use of NPs in various industries continues to grow along with the number of people suffering from chronic gastrointestinal diseases.

The Role of Metal Oxide Nanoparticles, Escherichia coli, and Lactobacillus rhamnosus on Small Intestinal Enzyme Activity

Engineered nanomaterials (ENMs) have become common in the food industry, which motivates the need to evaluate ENM effects on human health. Gastrointestinal (GI) in vitro models (e.g. Caco-2, Caco-2/HT29-MTX) have been used in nanotoxicology research. However, the human gut environment is composed of both human cells and the gut microbiota. The goal of this study is to increase the complexity of the Caco-2/HT29-MTX in vitro model by co-culturing human cells with the Gram-positive, commensal Lactobacillus rhamnosus or the Gram-negative, opportunistic Escherichia coli; with the hypothesis that the presence of bacteria would ameliorate the effects of exposure to metal oxide nanoparticles (NPs) such as iron oxide (Fe2O3), silicone dioxide (SiO2), titanium dioxide (TiO2), or zinc oxide (ZnO). To understand this relationship, Caco-2/HT29-MTX cell barriers were acutely co-exposed (4 hours) to bacteria and/or NPs (pristine or in vitro digested). The activity of the brush border membrane (BBM) enzymes intestinal alkaline phosphatase (IAP), aminopeptidase-N (APN), sucrase isomaltase (SI) and the basolateral membrane enzyme (BLM) Na+/K+ ATPase were assessed. Findings show that (i) the human digestion process alters the physicochemical properties of NPs, (ii) large agglomerates of NPs remain entrapped on the apical side of the intestinal barrier, which (iii) affects the activity of BBM enzymes. Interestingly, some NPs effects were attenuated in the presence of either bacterial strains. Confocal microscopy detected bacteria-NPs interactions, which may impede the NP-intestinal cell contact. These results highlight the importance of improving in vitro models to closely mimic the complexities of the human body.

Alteration in gut microbiota is associated with dysregulation of cytokines and glucocorticoid therapy in systemic lupus erythematosus

A growing corpus of evidence implicates the involvement of the commensal microbiota and immune cytokines in the initiation and progression of systemic lupus erythematosus (SLE). Glucocorticoids have been widely used in the treatment of SLE patients, however, glucocorticoid treatment carries a higher risk of other diseases. Using the 16S rRNA technique, we investigated the differences between the gut microbiota associated with the immune cytokines of SLE and relevant glucocorticoid treatment in a female cohort of 20 healthy control subjects (HC), 17 subjects with SLE (SLE-G), and 20 SLE patients having undergone glucocorticoid treatment (SLE+G). We observed that the diversity and structure of the microbial community in SLE+G patients were significantly changed compared to that of SLE-G patients, whereas the gut microbial community of the SLE+G group showed a similarity with the HC group, which implicate that the shift in the gut microbiome could represent a return to homeostasis. Furthermore, the up-regulations of immune cytokines in SLE-G were identified as closely related to gut dysbiosis, which indicates that the overrepresented genera in SLE patients may play roles in regulating expression level of these immune cytokines. This associated analysis of gut microbiota, glucocorticoid therapy, and immune factors might provide novel and insightful clues revealing the pathogenesis of SLE patients.

Impacts of foodborne inorganic nanoparticles on the gut microbiota-immune axis: potential consequences for host health

BACKGROUND

In food toxicology, there is growing interest in studying the impacts of foodborne nanoparticles (NPs, originating from food additives, food supplements or food packaging) on the intestinal microbiome due to the important and complex physiological roles of these microbial communities in host health. Biocidal activities, as described over recent years for most inorganic and metal NPs, could favour chronic changes in the composition and/or metabolic activities of commensal bacteria (namely, intestinal dysbiosis) with consequences on immune functions. Reciprocally, direct interactions of NPs with the immune system (e.g., inflammatory responses, adjuvant or immunosuppressive properties) may in turn have effects on the gut microbiota. Many chronic diseases in humans are associated with alterations along the microbiota-immune system axis, such as inflammatory bowel diseases (IBD) (Crohn's disease and ulcerative colitis), metabolic disorders (e.g., obesity) or colorectal cancer (CRC). This raises the question of whether chronic dietary exposure to inorganic NPs may be viewed as a risk factor facilitating disease onset and/or progression. Deciphering the variety of effects along the microbiota-immune axis may aid the understanding of how daily exposure to inorganic NPs through various foodstuffs may potentially disturb the intricate dialogue between gut commensals and immunity, hence increasing the vulnerability of the host. In animal studies, dose levels and durations of oral treatment are key factors for mimicking exposure conditions to which humans are or may be exposed through the diet on a daily basis, and are needed for hazard identification and risk assessment of foodborne NPs. This review summarizes relevant studies to support the development of predictive toxicological models that account for the gut microbiota-immune axis.

CONCLUSIONS

The literature indicates that, in addition to evoking immune dysfunctions in the gut, inorganic NPs exhibit a moderate to extensive impact on intestinal microbiota composition and activity, highlighting a recurrent signature that favours colonization of the intestine by pathobionts at the expense of beneficial bacterial strains, as observed in IBD, CRC and obesity. Considering the long-term exposure via food, the effects of NPs on the gut microbiome should be considered in human health risk assessment, especially when a nanomaterial exhibits antimicrobial properties.

Alginate oligosaccharides improve germ cell development and testicular microenvironment to rescue busulfan disrupted spermatogenesis

Rationale: Busulfan is currently an indispensable anti-cancer drug, particularly for children, but the side effects on male reproduction are so serious that critical drug management is needed to minimize any negative impact. Meanwhile, alginate oligosaccharides (AOS) are natural products with many consequent advantages, that have attracted a great deal of pharmaceutical attention. In the current investigation, we performed single-cell RNA sequencing on murine testes treated with busulfan and/or AOS to define the mitigating effects of AOS on spermatogenesis at the single cell level.

Methods: Testicular cells (in vivo) were examined by single cell RNA sequencing analysis, histopathological analysis, immunofluorescence staining, and Western blotting. Testes samples (ex vivo) underwent RNA sequencing analysis. Blood and testicular metabolomes were determined by liquid chromatography-mass spectrometry (LC/MS).

Results: We found that AOS increased murine sperm concentration and motility, and rescued busulfan disrupted spermatogenesis through improving (i) the proportion of germ cells, (ii) gene expression important for spermatogenesis, and (iii) transcriptional factors in vivo. Furthermore, AOS promoted the ex vivo expression of genes important for spermatogenesis. Finally, our results showed that AOS improved blood and testis metabolomes as well as the gut microbiota to support the recovery of spermatogenesis.

Conclusions: AOS could be used to improve fertility in patients undergoing chemotherapy and to combat other factors that induce infertility in humans.

Effect of zinc oxide nanoparticles on broilers' performance and health status

The current study investigated the effects of zinc oxide nanoparticles (ZONPs) and oxytetracycline (OTC) supplementation on broilers' behavior, performance, carcass quality, biochemical parameters, and intestinal microbial populations and birds' response to Newcastle disease (ND) vaccine. A total of 336 seven-day-old IR broiler chicks were randomly allotted to six dietary treatments containing 0, 10, 20, 30 and 40 ppm ZONPs or 50 ppm OTC. Each diet was fed to 7 replicates (8 birds/pen). The results clarified that 10 ppm ZONPs significantly improved the body weight gain and feed conversion in comparison to the control. No changes in behavior were recorded. The 10 ppm and 30 ppm ZONPs and OTC significantly reduced the gizzard weight in comparison to the control. While, 10 ppm ZONPs significantly increased the spleen weight, and all ZONPs doses increased bursa weight in comparison to the control and OTC groups. 20 ppm ZONPs increased the eviscerated yield and edible yield in comparison to the control and OTC groups. 40 ppm ZONPs increased pH, reduced meat color and overall acceptability in comparison to the control. In addition, results revealed that the 20 ppm ZONPs increased Calcium (Ca), High density low cholesterol (HDL-C), reduced urea (UA) and triglyceride (TG). Also, 40 ppm ZONPs and OTC increased creatinine (Cr) and reduced ND-HI titer in comparison to the control. For microbial population, OTC group was significantly lower than ZONPs groups in the total anaerobic, aerobic and lactobacilli count. In conclusion, the dietary inclusion of ZONPs can be applied as antibiotic growth promoter substitutions in broilers' diet. However, further investigations are still needed.

ZnO Modulates Swine Gut Microbiota and Improves Growth Performance of Nursery Pigs When Combined with Peptide Cocktail

Zinc has been very efficacious in reducing post-weaning diarrhea, whereas animal-derived peptides are suggested to improve the growth performance of weaned piglets. However, the combined effect of zinc and peptides on swine production and swine gut microbiota is still largely unknown. In this study, we followed 288 nursery pigs from the age of d30 to d60 to evaluate the growth performance and gut microbiota of weanling pigs subjected to different levels of a fish-porcine-microbial peptide cocktail (0.05%, 0.25%, and 0.5%) with or without the pharmaceutical level of zinc oxide (ZnO) (2500 ppm) supplementation in a nutrient-deficient diet. Rectal swab samples were collected from pigs with body weight (BW) approach average at each pen on d30, d42, and d60 to determine gut microbiota. Average daily gain (ADG) and BW in piglets fed high zinc (HZ) increased with increasing levels of peptide. The microbiota of the HZ group also diverged from those of the standard zinc (SZ) group from d30 to d60. Adding peptide did not alter community structure regardless of zinc supplementation. Collectively, these findings demonstrated that the pharmaceutical level of zinc as ZnO conditioned the gut community to the point where peptide could effectively restore growth performance in nursery pigs fed nutrient-deficient diets.

Microbial synthesis of zinc oxide nanoparticles and their potential application as an antimicrobial agent and a feed supplement in animal industry: a review

In recent years, zinc oxide nanoparticles (ZnO NPs) have gained tremendous attention attributed to their unique properties. Notably, evidence has shown that zinc is an important nutrient in living organisms. As such, both prokaryotes and eukaryotes including bacteria, fungi and yeast are exploited for the synthesis of ZnO NPs by using microbial cells or enzyme, protein and other biomolecules compounds in either an intracellular or extracellular route. ZnO NPs exhibit antimicrobial properties, however, the properties of nanoparticles (NPs) are depended upon on their size and shape, which make them specific for various applications. Nevertheless, the desired size and shape of NPs can be obtained through the optimization process of microbes mediated synthesis by manipulating their reaction conditions. It should be noted that ZnO NPs are synthesized by various chemical and physical methods. Nonetheless, these methods are expensive and not environmentally friendly. On that account, the microbes mediated synthesis of ZnO NPs have rapidly evolved recently where the microbes are cleaner, eco-friendly, non-toxic and biocompatible as the alternatives to chemical and physical practices. Moreover, zinc in the form of NPs is more effective than their bulk counterparts and thus, they have been explored for many potential applications including in animals industry. Notably, with the advent of multi-drug resistant strains, ZnO NPs have emerged as the potential antimicrobial agents. This is mainly due to their superior properties in combating a broad spectrum of pathogens. Moreover, zinc is known as an essential trace element for most of the biological function in the animal's body. As such, the applications of ZnO NPs have been reported to significantly enhance the health and production of the farm animals. Thus, this paper reviews the biological synthesis of ZnO NPs by the microbes, the mechanisms of the biological synthesis, parameters for the optimization process and their potential application as an antimicrobial agent and feed supplement in the animal industry as well as their toxicological hazards on animals.

In-feed bacitracin methylene disalicylate modulates the turkey microbiota and metabolome in a dose-dependent manner

Beginning in 2017, the subtherapeutic use of most antibiotic compounds for growth promotion in food producing animals in the US was prohibited, highlighting the need to discover alternative growth promotants. Identifying the mechanism of action of growth promoting antibiotics may aid in the discovery of antibiotic alternatives. We describe the effects of feeding a subtherapeutic (50 g/ton of feed) and therapeutic (200 g/ton) concentration of bacitracin methylene disalicylate (BMD) to commercial turkeys for 14 weeks, and its effect on turkey intestinal microbial communities and cecal metabolomes. Both BMD concentrations had an immediate and lasting impact on the microbiota structure, and reduced bacterial richness through the end of the study (12 weeks). Metabolomic analysis identified 712 biochemicals, and 69% of metabolites were differentially present in BMD treated turkeys for at least one time point (q < 0.1). Amino acids, carbohydrates, nucleotides, peptides, and lipids were decreased in the turkey ceca early after BMD administration. Long-term metabolome alterations continued even after withdrawal of BMD. The microbial composition, determined by 16S rRNA gene sequencing, was predictive of the metabolome, indicating a connection between the microbiome and metabolome. In-feed BMD may cause bacterial metabolic shifts, leading to beneficial traits that can be targeted to improve animal health and production.

Gold Nanoparticles Cure Bacterial Infection with Benefit to Intestinal Microflora

Antibiotics that are most used to cure bacterial infections in the clinic result in the imbalance of intestinal microflora, destroy the intestinal barrier, and induce bacterial resistance. There is an urgent need for antibacterial agent therapy for bacterial infections that does not destroy intestinal microflora. Herein, we applied 4,6-diamino-2-pyrimidinethiol (DAPT)-coated Au nanoparticles (D-Au NPs) for therapy of bacterial infection induced by Escherichia coli ( E. coli) in the gut. We cultured D-Au NPs and E. coli in an anaerobic atmosphere to evaluate their bactericidal effect. We studied the microflora, distribution of Au, and biomarkers in mice after a 28-day oral administration to analyze the effect of Au NPs on mice. D-Au NPs cured bacterial infections more effectively than levofloxacin without harming intestinal microflora. D-Au NPs showed great potential as alternatives to oral antibiotics.

Zinc phosphate-based nanoparticles as a novel antibacterial agent: in vivo study on rats after dietary exposure

Background

Development of new nanomaterials that inhibit or kill bacteria is an important and timely research topic. For example, financial losses due to infectious diseases, such as diarrhea, are a major concern in livestock productions around the world. Antimicrobial nanoparticles (NPs) represent a promising alternative to antibiotics and may lower antibiotic use and consequently spread of antibiotic resistance traits among bacteria, including pathogens.

Results

Four formulations of zinc nanoparticles (ZnA, ZnB, ZnC, and ZnD) based on phosphates with spherical (ZnA, ZnB) or irregular (ZnC, ZnD) morphology were prepared. The highest in vitro inhibitory effect of our NPs was observed against Staphylococcus aureus (inhibitory concentration values, IC₅₀, ranged from 0.5 to 1.6 mmol/L), followed by Escherichia coli (IC₅₀ 0.8-1.5 mmol/L). In contrast, methicillin resistant S. aureus (IC₅₀ 1.2-4.7 mmol/L) was least affected and this was similar to inhibitory patterns of commercial ZnO-based NPs and ZnO. After the successful in vitro testing, the in vivo study with rats based on dietary supplementation with zinc NPs was conducted. Four groups of rats were treated by 2,000 mg Zn/kg diet of ZnA, ZnB, ZnC, and ZnD, for comparison two groups were supplemented by 2,000 mg Zn/kg diet of ZnO-N and ZnO, and one group (control) was fed only by basal diet. The significantly higher (P < 0.05) Zn level in liver and kidney of all treated groups was found, nevertheless Zn NPs did not greatly influence antioxidant status of rats. However, the total aerobic and coliform bacterial population in rat feces significantly decreased (P < 0.05) in all zinc groups after 30 d of the treatment. Furthermore, when compared to the ZnO group, ZnA and ZnC nanoparticles reduced coliforms significantly more (P < 0.05).

Conclusions

Our results demonstrate that phosphate-based zinc nanoparticles have the potential to act as antibiotic agents.

The gut microbiome and aquatic toxicology: An emerging concept for environmental health

The microbiome plays an essential role in the health and onset of diseases in all animals, including humans. The microbiome has emerged as a central theme in environmental toxicology because microbes interact with the host immune system in addition to its role in chemical detoxification. Pathophysiological changes in the gastrointestinal tissue caused by ingested chemicals and metabolites generated from microbial biodegradation can lead to systemic adverse effects. The present critical review dissects what we know about the impacts of environmental contaminants on the microbiome of aquatic species, with special emphasis on the gut microbiome. We highlight some of the known major gut epithelium proteins in vertebrate hosts that are targets for chemical perturbation, proteins that also directly cross-talk with the microbiome. These proteins may act as molecular initiators for altered gut function, and we propose a general framework for an adverse outcome pathway that considers gut dysbiosis as a major contributing factor to adverse apical endpoints. We present 2 case studies, nanomaterials and hydrocarbons, with special emphasis on the Deepwater Horizon oil spill, to illustrate how investigations into the microbiome can improve understanding of adverse outcomes. Lastly, we present strategies to functionally relate chemical-induced gut dysbiosis with adverse outcomes because this is required to demonstrate cause-effect relationships. Further investigations into the toxicant-microbiome relationship may prove to be a major breakthrough for improving animal and human health. Environ Toxicol Chem 2018;37:2758-2775. © 2018 SETAC.

Intestinal microbiome of broiler chickens after use of nanoparticles and metal salts

The research included the study of influence of ultrafine particle preparations (nanoparticles of copper, zinc, iron, CuZn alloy) and metal salts (iron pyrophosphate, copper asparginate, zinc asparginate) on the composition of cecal microbiota of broiler chickens. Before adding the studied nanoparticles and metal salts to the diet, cecal microbiota of broiler chickens was represented by 76% Firmicutes taxon and 16% Bacteroidetes. Numerous among them were the bacteria of the taxa Anaerotruncus spp., Lactobacillus spp., Blautia spp., Alistipes spp., and Bacteroides spp.; they constituted 18, 17, 11, and 6%, respectively. A peculiarity of action of the most analyzed metals in nanoform and in the form of salts was a decrease in the number of phylum Firmicutes bacteria and an increase in the number of microorganisms of the phylum Bacteroidetes. The number of bacteria belonging to the families Ruminococcaceae (III, IV, V, VII, and VIII groups), Bacteroidaceae (in all experimental groups), and Lachnospiraceae (I, IV, V, and VII groups) was registered within the taxa of Firmicutes and Bacteroidetes. At the same time, in some experimental groups, the number of bacteria of the family Lachnospiraceae (II, III, and VIII) decreased in the intestine. The data obtained can be used to assess the possibility of using metal nanoparticles in the poultry diet, as a micronutrient preparation, to correct dysbiosis and to improve the utilization of fodder energy.

Mechanistic insights into the protective impact of zinc on sepsis

Sepsis, a systemic inflammation as a response to a bacterial infection, is a huge unmet medical need. Data accumulated over the last decade suggest that the nutritional status of patients as well as composition of their gut microbiome, are strongly linked with the risk to develop sepsis, the severity of the disease and prognosis. In particular, the essential micronutrient zinc is essential in the resistance against sepsis and has shown to be protective in animal models as well as in human patients. The potential mechanisms by which zinc protects in sepsis are discussed in this review paper: we will focus on the inflammatory response, chemotaxis, phagocytosis, immune response, oxidative stress and modulation of the microbiome. A full understanding of the mechanism of action of zinc may open new preventive and therapeutic interventions in sepsis.

Pro-Inflammatory versus Immunomodulatory Effects of Silver Nanoparticles in the Lung: The Critical Role of Dose, Size and Surface Modification

The growing use of silver nanoparticles (Ag-NPs) in consumer products raises concerns about their toxicological potential. The purpose of the study was to investigate the size- and coating-dependent pulmonary toxicity of Ag-NPs in vitro and in vivo, using an ovalbumin (OVA)-mouse allergy model. Supernatants from (5.6-45 µg/mL) Ag50-PVP, Ag200-PVP or Ag50-citrate-treated NR8383 alveolar macrophages were tested for lactate dehydrogenase and glucuronidase activity, tumor necrosis factor (TNF)-α release and reactive oxygen species (ROS) production. For the in vivo study, NPs were intratracheally instilled in non-sensitized (NS) and OVA-sensitized (S) mice (1-50 µg/mouse) prior to OVA-challenge and bronchoalveolar lavage fluid (BALF) inflammatory infiltrate was evaluated five days after challenge. In vitro results showed a dose-dependent cytotoxicity of Ag-NPs, which was highest for Ag50-polyvinilpyrrolidone (PVP), followed by Ag50-citrate, and lowest for Ag200-PVP. In vivo 10-50 µg Ag50-PVP triggered a dose-dependent pulmonary inflammatory milieu in NS and S mice, which was significantly higher in S mice and was dampened upon instillation of Ag200-PVP. Surprisingly, instillation of 1 µg Ag50-PVP significantly reduced OVA-induced inflammatory infiltrate in S mice and had no adverse effect in NS mice. Ag50-citrate showed similar beneficial effects at low concentrations and attenuated pro-inflammatory effects at high concentrations. The lung microbiome was altered by NPs instillation dependent on coating and/or mouse batch, showing the most pronounced effects upon instillation of 50 µg Ag50-citrate, which caused an increased abundance of operational taxonomic units assigned to Actinobacteria, Bacteroidetes, Firmicutes and Proteobacteria. However, no correlation with the biphasic effect of low and high Ag-NPs dose was found. Altogether, both in vitro and in vivo data on the pulmonary effects of Ag-NPs suggest the critical role of the size, dose and surface functionalization of Ag-NPs, especially in susceptible allergic individuals. From the perspective of occupational health, care should be taken by the production of Ag-NPs-containing consumer products.

Age-Related Variations in Intestinal Microflora of Free-Range and Caged Hens

Free range feeding pattern puts the chicken in a mixture of growth materials and enteric bacteria excreted by nature, while it is typically unique condition materials and enteric bacteria in commercial caged hens production. Thus, the gastrointestinal microflora in two feeding patterns could be various. However, it remains poorly understood how feeding patterns affect development and composition of layer hens’ intestinal microflora. In this study, the effect of feeding patterns on the bacteria community in layer hens’ gut was investigated using free range and caged feeding form. Samples of whole small intestines and cecal digesta were collected from young hens (8-weeks) and mature laying hens (30-weeks). Based on analysis using polymerase chain reaction-denaturing gradient gel electrophoresis and sequencing of bacterial 16S rDNA gene amplicons, the microflora of all intestinal contents were affected by both feeding patterns and age of hens. Firmicutes, Bacteroidetes, Actinobacteria, Proteobacteria, and Fusobacteria were the main components. Additionally, uncultured environmental samples were found too. There were large differences between young hens and adult laying hens, the latter had more Firmicutes and Bacteroidetes, and bacterial community is more abundant in 30-weeks laying hens of all six phyla than 8-weeks young hens of only two phyla. In addition, the differences were also observed between free range and caged hens. Free range hens had richer Actinobacteria, Bacteroidetes, and Proteobacteria. Most of strains found were detected more abundant in small intestines than in cecum. Also the selected Lactic acid bacteria from hens gut were applied in feed and they had beneficial effects on growth performance and jejunal villus growth of young broilers. This study suggested that feeding patterns have an importance effect on the microflora composition of hens, which may impact the host nutritional status and intestinal health.