Nonclinical toxicology development of a novel antibody antibiotic conjugate for treating invasive Staphylococcus Aureus infections.

Invasive Staphylococcus aureus (S. aureus) infections are a leading cause of death and not effectively treated with prolonged standard of care antibiotics. A novel THIOMAB™ antibody antibiotic conjugate (TAC) was developed that uses a bacterial-wall specific antibody to deliver the antibiotic (dmDNA31, a rifamycin analogue) to bacteria to minimize toxicities typically seen with prolonged use of traditional antibiotics. The TAC nonclinical toxicology package included repeat dose rat and cynomolgus monkey toxicology studies for 8 weekly intravenous (IV) doses, a 7-day daily repeat dose IV toxicology study of dmDNA31 and an assessment of genotoxicity, cardiovascular toxicity, neurotoxicity and sperm parameters. TAC and dmDNA31 were well tolerated in rats and monkeys, and there was no evidence of genotoxicity, cardiovascular toxicity or neurotoxicity. Non-adverse findings were observed and included blue discoloration in skin, blood, etc. due to the blue color of dmDNA31, increased globulin due to the high doses of antibodies, and abnormal sperm morphology of small heads in male rats with no histopathology correlate in testis. This is an example of antibody-mediated delivery of an antibiotic that has the potential to offer a more effective way of eradicating infection while providing a better safety profile compared to traditional antibiotics.

Microcystin-Induced Immunotoxicity in Fishes: A Scoping Review.

Cyanobacteria (blue-green algae) have been present on Earth for over 2 billion years, and can produce a variety of bioactive molecules, such as cyanotoxins. Microcystins (MCs), the most frequently detected cyanotoxins, pose a threat to the aquatic environment and to human health. The classic toxic mechanism of MCs is the inhibition of the protein phosphatases 1 and 2A (PP1 and PP2A). Immunity is known as one of the most important physiological functions in the neuroendocrine-immune network to prevent infections and maintain internal homoeostasis in fish. The present review aimed to summarize existing papers, elaborate on the MC-induced immunotoxicity in fish, and put forward some suggestions for future research. The immunomodulatory effects of MCs in fish depend on the exposure concentrations, doses, time, and routes of exposure. Previous field and laboratory studies provided strong evidence of the associations between MC-induced immunotoxicity and fish death. In our review, we summarized that the immunotoxicity of MCs is primarily characterized by the inhibition of PP1 and PP2A, oxidative stress, immune cell damage, and inflammation, as well as apoptosis. The advances in fish immunoreaction upon encountering MCs will benefit the monitoring and prediction of fish health, helping to achieve an ecotoxicological goal and to ensure the sustainability of species. Future studies concerning MC-induced immunotoxicity should focus on adaptive immunity, the hormesis phenomenon and the synergistic effects of aquatic microbial pathogens.

A Single-Domain Antibody-Based Anti-PSMA Recombinant Immunotoxin Exhibits Specificity and Efficacy for Prostate Cancer Therapy.

Prostate cancer (PCa) is the second most common cancer in men, causing more than 300,000 deaths every year worldwide. Due to their superior cell-killing ability and the relative simplicity of their preparation, immunotoxin molecules have great potential in the clinical treatment of cancer, and several such molecules have been approved for clinical application. In this study, we adopted a relatively simple strategy based on a single-domain antibody (sdAb) and an improved Pseudomonas exotoxin A (PE) toxin (PE24X7) to prepare a safer immunotoxin against prostate-specific membrane antigen (PSMA) for PCa treatment. The designed anti-PSMA immunotoxin, JVM-PE24X7, was conveniently prepared in its soluble form in an Escherichia coli (E. coli) system, avoiding the complex renaturation process needed for immunotoxin preparation by the conventional strategy. The product was very stable and showed a very strong ability to bind the PSMA receptor. Cytotoxicity assays showed that this molecule at a very low concentration could kill PSMA-positive PCa cells, with an EC50 value (concentration at which the cell viability decreased by 50%) of 15.3 pM against PSMA-positive LNCaP cells. Moreover, this molecule showed very good killing selectivity between PSMA-positive and PSMA-negative cells, with a selection ratio of more than 300-fold. Animal studies showed that this molecule at a very low dosage (5 × 0.5 mg/kg once every three days) completely inhibited the growth of PCa tumors, and the maximum tolerable dose (MTD) was more than 15 mg/kg, indicating its very potent tumor-treatment ability and a wide therapeutic window. Use of the new PE toxin, PE24X7, as the effector moiety significantly reduced off-target toxicity and improved the therapeutic window of the immunotoxin. The above results demonstrate that the designed anti-PSMA immunotoxin, JVM-PE24X7, has good application value for the treatment of PCa.

Effects of noise and low-concentration carbon monoxide exposure on rat immunity.

OBJECTIVE: To evaluate the immunotoxicity and effects of noise and/or low-concentration carbon monoxide (CO) exposure on immune organs and immune functions in rats. METHODS: Male Wistar rats exposed to 98 dB(A) white noise and/or 100 ppm CO 4 h/d for 30 d were used to determine the pathological changes in the thymus and spleen, and variations in leukocyte counts, inflammatory factors, and immunoglobulin (Ig) concentrations. RESULTS: The boundaries of the cortex and medulla of the thymus were unclear following noise and combined exposure. The pathological changes in spleen after CO and combined exposure included blurred boundaries of red-pulp and white-pulp, disappearance of normal splenic nodules and neutrophil infiltration. After exposure to noise and in combination, leukocyte and lymphocyte counts decreased significantly. After exposure to low-concentration CO and in combination, serum IgM and IgG levels decreased significantly, but the levels of tumor necrosis factor-α and interferon-γ levels increased significantly. Eosinophils and IgA levels decreased significantly following exposure to noise and/or low concentration of CO, while the level of interleukin-1 increased significantly. Monocytes increased significantly only under noise or CO exposure, but not under combined exposure. CONCLUSIONS: Noise and/or low-concentration CO exposure may suppress innate and adaptive immune functions and induce inflammatory responses. Noise exposure mainly affected the innate immune function of rats, whereas low-concentration CO exposure mainly affected adaptive immune functions. Combined exposure presented higher immunotoxicity than noise or CO alone, suggesting that exposure to noise and low-concentration CO in the living and working environments can affect the immune system.

Triton X-114 and Amine-Based Wash Strategy Reduces Lipopolysaccharides to FDA Limit and Achieves Purer, More Potent Recombinant Immunotoxin.

Many proteins are still routinely expressed prokaryotically in Escherichia coli, some because they are toxic to eukaryotes. Immunotoxins, which are fusion proteins of a targeting moiety and a truncated Pseudomonas exotoxin A, kill target cells by arresting protein synthesis. Thus, immunotoxins must be expressed in E. coli. Proteins expressed in E. coli are contaminated by endotoxin (also called lipopolysaccharides (LPS)). LPS binds to toll-like receptors, inducing up to life-threatening systemic inflammation in mammals. Therefore, accepted LPS limits for therapeutics as well as for substances used in immunological studies in animals are very low. Here, we report the use of Triton X-114 and polyamine-based wash strategies, which only in combination achieved LPS-contamination well below FDA limits. Resulting LPS-reduced immunotoxins were purer and up to 2.4-fold more active in vitro. Increased activity was associated with a 2.4-fold increase in affinity on cell surface expressed target antigen. The combination method maintained enzymatic function, protein stability, and in vivo efficacy and was effective for Fab as well as dsFv formats. With some modifications, the principle of this novel combination may be applied to any chromatography-based purification process.

Perfluorooctanoic acid-induced immunotoxicity via NF-kappa B pathway in zebrafish (Danio rerio) kidney.

Perfluorooctanoic acid (PFOA) is widely used in industrial production due to its stable chemical structure and hydrophobic and oleophobic characteristics. PFOA has been frequently detected in environmental media and organisms, leading to increased health risks. There is a lack of information about the immunotoxicity of aquatic organisms induced by PFOA, and the molecular mechanisms remain unclear. In this study, LC-MS analysis proved that PFOA can accumulate in the kidney of zebrafish. In the 0.05 mg/L PFOA treatment group, the accumulation of PFOA in the kidney after 21 days of exposure significantly increased by 79.89%, compared to 14 days of exposure. And a hydropic endoplasmic reticulum, swelling of mitochondria and vacuolization were observed in kidney immune cells of zebrafish. The Toll-like receptor 2 (TLR2)/myeloid differentiation factor 88 (myd88)/NF-κB (P65) pathway was activated when PFOA exerted its effects, which led to regulation of antibody expression; RT-PCR results showed that the mRNA expression level of interleukin-4 (IL-4) decreased in a dose-dependent manner, decreasing to 29.6% of the control level in the 1 mg/L PFOA group after 21 d of exposure. According to triangle plot analysis, immunoglobulin exhibited a notable stress response to PFOA at an early phase; a high concentration of PFOA may disrupt the immune system of zebrafish. Third-order polynomial fitting analysis showed that the high-mRNA-expression regions of IL-4 and antibodies were partially consistent. The results indicated that PFOA could affect antibodies by increasing the concentrations of proinflammatory cytokines. Changes in antibody levels further influenced the expression of other cytokines, which eventually caused disorders in the zebrafish immune system. This study expands the understanding of PFOA-induced immunosuppression and suggests that toxicity mechanisms should be considered for further health risk assessment of emerging pollutants.

Indirect podocyte injury manifested in a partial podocytectomy mouse model.

In progressive glomerular diseases, segmental podocyte injury often expands, leading to global glomerulosclerosis by unclear mechanisms. To study the expansion of podocyte injury, we established a new mosaic mouse model in which a fraction of podocytes express human (h)CD25 and can be injured by the immunotoxin LMB2. hCD25+ and hCD25- podocytes were designed to express tdTomato and enhanced green fluorescent protein (EGFP), respectively, which enabled cell sorting analysis of podocytes. After the injection of LMB2, mosaic mice developed proteinuria and glomerulosclerosis. Not only tdTomato+ podocytes but also EGFP+ podocytes were decreased in number and showed damage, as evidenced by a decrease in nephrin and an increase in desmin at both protein and RNA levels. Transcriptomics analysis found a decrease in the glucocorticoid-induced transcript 1 gene and an increase in the thrombospondin 4, heparin-binding EGF-like growth factor, and transforming growth factor-ß genes in EGFP+ podocytes; these genes may be candidate mediators of secondary podocyte damage. Pathway analysis suggested that focal adhesion, integrin-mediated cell adhesion, and focal adhesion-phosphatidylinositol 3-kinase-Akt-mammalian target of rapamycin signaling are involved in secondary podocyte injury. Finally, treatment of mosaic mice with angiotensin II receptor blocker markedly ameliorated secondary podocyte injury. This mosaic podocyte injury model has distinctly demonstrated that damaged podocytes cause secondary podocyte damage, which may be a promising therapeutic target in progressive kidney diseases.NEW & NOTEWORTHY This novel mosaic model has demonstrated that when a fraction of podocytes is injured, other podocytes are subjected to secondary injury. This spreading of injury may occur ubiquitously irrespective of the primary cause of podocyte injury, leading to end-stage renal failure. Understanding the molecular mechanism of secondary podocyte injury and its prevention is important for the treatment of progressive kidney diseases. This model will be a powerful tool for studying the indirect podocyte injury.

Evaluation of an in vitro assay to screen for the immunotoxic potential of chemicals to fish.

A wide variety of environmental contaminants has been shown to disrupt immune functions of fish and may compromise their defense capability against pathogens. Immunotoxic effects, however, are rarely considered in ecotoxicological testing strategies. The aim of this study was to systematically evaluate the suitability of an in vitro immuno-assay using selected fish immune parameters to screen for chemicals with known immunotoxic potential and to differentiate them from non-immunotoxicants. Non-stimulated and lipopolysaccharide-stimulated head kidney leukocytes of rainbow trout (Oncorhynchus mykiss) were exposed for 3 h or 19 h to chemicals with different modes of action. As immune parameters, phagocytosis activity, oxidative burst activity and cytokine transcription (IL-1ß, TNFα, IL-10) were examined, accompanied by in silico modelling. The immunotoxicants dexamethasone, benzo(a)pyrene, ethinylestradiol and bisphenol A significantly altered the immune parameters at non-cytotoxic concentrations whereas diclofenac had only weak effects. However, the two baseline chemicals with no known immunotoxic potential, butanol and ethylene glycol, caused significant effects, too. From our results it appears that the in vitro fish leukocyte assay as performed in the present study has only a limited capacity for discriminating between immunotoxicants and non-immunotoxicants.

Effects of an environmentally relevant PCB-mixture on immune function, clinical chemistry, and thyroid hormone levels in adult female B6C3F1 mice.

Polychlorinated biphenyls (PCBs) have been assessed for immunotoxicity; however, humans and wildlife are exposed to multiple PCBs environmentally. Therefore, the aim of this study was to examine the effects of a complex 37 PCB congener mixture identified in blubber specific to dolphins residing in the estuarine waters of Charleston, South Carolina. Immunotoxicity was determined in adult female B6C3F1 mice by assessing lymphocyte proliferation, splenic and thymic immunophenotypes, and IgM production. Mice were exposed via oral gavage to the PCB-mixture (0, 1.8, 3.6, 7.1, or 14.3 mg/kg/day) for 28 days to yield a targeted total administered dose (TAD) 0, 50, 100, 200, or 400 mg/kg. Significant increased liver weight occurred at the highest treatment. IgM production was suppressed compared to control for all treatments. Numbers of thymic CD4+/CD8+, CD4-/CD8-, and CD4+/CD8- cells were not altered, but numbers of thymic CD4-/CD8+ cells were significantly increased in the highest treatment. Lymphocyte proliferation was not markedly affected by any treatment. The numbers of splenic CD4/CD8 T-cells or MHCII+ cells were not significantly changed. Humoral immunity using the plaque-forming cell assay for determining the specific IgM antibody-forming cell response appeared to be the most sensitive endpoint affected. As the lowest concentration tested resulted in decreased IgM production and total and free thyroxine (T4) serum levels a NOAEL was not identified. The calculated ED50 for suppression of IgM production was 2.4 mg/kg/day.

Decrease in immune function and the role of mitogen-activated protein kinase (MAPK) overactivation in apoptosis during T lymphocytes activation induced by zearalenone, deoxynivalenol, and their combinations.

Currently there are few reports on the combined immunotoxicity of zearaleone (ZEA) and deoxynivalenol (DON). Since the two coexist naturally, it is necessary to understand the immunotoxicity caused by the two mycotoxins alone and in combination. To examine T lymphocytes activation and immune effect during activation, we used mouse primary spleen T lymphocytes as the experimental material and concanavalin (Con A) as the stimulator. The effects of ZEA, DON, and their combined exposure on T lymphocytes immune related function and the relationship between the activation of the mitogen-activated protein kinase (MAPK) signaling pathway and mycotoxin induced T lymphocytes apoptosis were studied in vitro. Specifically, T lymphocytes were isolated from primary mouse splenic lymphocytes, activated by Con A and then exposed to different concentrations of ZEA, DON, and their combinations. Our results showed that ZEA and DON alone and their combinations (20:1) can decrease the cell viability of T lymphocytes activated by Con A. The inhibitory effect of the combined groups was greater than that of the single mycotoxins, showing a synergistic effect. In addition, single or combined mycotoxins can lead to intracellular and surface ultrastructure damage of T lymphocytes, inhibit the expression of CD25 and CD278 and inhibit the synthesis of effect molecules poreforming protein (PFP), granzyme A (GZMA), and tumor necrosis factor-α (TNF-α). Meanwhile, the single mycotoxin or combined mycotoxins can promote the apoptosis of T lymphocytes which was accompanied by the overactivation of MAPK. After using the inhibitors of extracellular regulated protein kinases (ERK) and c-Jun N-terminal kinase (JNK) in the MAPK pathway, we found that the apoptosis of the cells induced by the ZEA was significantly decreased, and the apoptosis of the cells induced by DON had no significant changes. This suggests that the activation of MAPK induced by ZEA can promote the apoptosis of T lymphocytes, but the activation of MAPK induced by DON is not directly related to T cell apoptosis.

Fumonisin B1 triggers the formation of bovine neutrophil extracellular traps.

Fumonisin B1 (FB1) is a congener of fumonisins produced by Fusarium species that may be found as corn contaminants threatening health of humans and animals. FB1 causes a variety of toxicity effects, including hepatotoxic, nephrotoxic and cytotoxic effects. However, detailed mechanisms associated with FB1 immunotoxicity in neutrophils are still unclear. To accomplish this, we utilized neutrophils to study the mechanisms of FB1 immunotoxicity. In the current study, we found that FB1 induced the formation of neutrophil extracellular traps (NETs), increased reactive oxygen species (ROS) levels, and decreased SOD and CAT activities. Concurrently, FB1 treatment led to the concentration-dependent phosphorylation of ERK-1/2 and p38 in neutrophils. Moreover, we demonstrated that FB1-induced NET formation was dependent of NADPH oxidase activity. Pretreatment of neutrophils with DPI, U0126 and SB202190 significantly reduced ROS generation, and prevented NET formation, further suggesting that ROS dependent activation of ERK 1/2 and p38 pathways, which possibly mediate FB1-induced NET release in neutrophils. Thus, NET formation and ROS production could be attributed to FB1 immunotoxicity, which might enrich the toxicological mechanisms of FB1.

A novel in vivo model using immunotoxin in the absence of p-glycoprotein to achieve ultra selective depletion of target cells: Applications in trogocytosis and beyond.

A commonly employed method to determine the function of a particular cell population and to assess its contribution to the overall system in vivo is to selectively deplete that population and observe the effects. Using monoclonal antibodies to deliver toxins to target cells can achieve this with a high degree of efficiency. Here, we describe an in vivo model combining the use of immunotoxins and multidrug resistant (MDR) gene deficient mice so that only MDR deficient cells expressing the target molecule would be depleted while target molecule expressing, but MDR sufficient, cells are spared. This allows targeted depletion at a higher degree of specificity than has been previously achieved. We have applied this technique to study trogocytosis, the intercellular transfer of cell surface molecules, but this principle could also be adapted using technology already available for use in other fields of study.

Identification of novel long non-coding RNAs involved in bisphenol A induced immunotoxicity in fish primary macrophages.

Bisphenol A (BPA), a well-known environmental endocrine-disrupting chemical (EDC), could pose a great toxicity risk to aquatic organisms. The present study aimed to evaluate the underlying role of long non-coding RNAs (lncRNAs) in BPA-induced immunotoxicity in head kidney (HK) macrophages of the red common carp (Cyprinus carpio), using lncRNA-RNA sequencing (RNA-Seq). In BPA-exposed HK macrophages group, 2,095 and 1,138 differentially expressed mRNAs (DEGs) and lncRNAs (DE-lncRNAs) were obtained, respectively, compared with controls. The qRT-PCR validation results of DEGs and DE-lncRNAs were similar to the RNA-Seq results. The KEGG analysis of DEGs and target genes of DE-lncRNAs have shown that some immune-related signaling pathways, including NF-kappa B, Toll-like receptor, B-cell receptor, Jak-STAT, and Hippo signaling pathways, were severely disrupted by BPA exposure. Moreover, we observed the synergic regulation of some mRNAs involved in immune response such as two hub genes traf6 and mapk1/3 and their upstream lncRNAs in HK macrophages upon the BPA exposure or its analogue bisphenol S (BPS) exposure. This suggested the dysregulation of lncRNAs by BPA or BPS may lead to a change in the expression of hub genes, which affects the cross-talk of various signaling pathways by interaction with other network genes. In conclusion, the present study demonstrates the potential role of lncRNAs in immunotoxicity of bisphenol compounds in red common carp HK macrophages, and our results provide evidence for further exploring lncRNA's role in EDC-induced toxicity in aquatic organisms.

Immunotoxin SS1P is rapidly removed by proximal tubule cells of kidney, whose damage contributes to albumin loss in urine.

Recombinant immunotoxins (RITs) are chimeric proteins composed of an Fv and a protein toxin being developed for cancer treatment. The Fv brings the toxin to the cancer cell, but most of the RITs do not reach the tumor and are removed by other organs. To identify cells responsible for RIT removal, and the pathway by which RITs reach these cells, we studied SS1P, a 63-kDa RIT that targets mesothelin-expressing tumors and has a short serum half-life. The major organs that remove RIT were identified by live mouse imaging of RIT labeled with FNIR-Z-759. Cells responsible for SS1P removal were identified by immunohistochemistry and intravital two-photon microscopy of kidneys of rats. The primary organ of SS1P removal is kidney followed by liver. In the kidney, SS1P passes through the glomerulus, is taken up by proximal tubular cells, and transferred to lysosomes. In the liver, macrophages are involved in removal. The short half-life of SS1P is due to its very rapid filtration by the kidney followed by degradation in proximal tubular cells of the kidney. In mice treated with SS1P, proximal tubular cells are damaged and albumin in the urine is increased. SS1P uptake by kidney is reduced by coadministration of l-lysine. Our data suggests that l-lysine administration to humans might prevent SS1P-mediated kidney damage, reduce albumin loss in urine, and alleviate capillary leak syndrome.

Immunotoxicity and transcriptome analysis of zebrafish embryos in response to glufosinate-ammonium exposure.

Glufosinate-ammonium (Gla) is a broad-spectrum and non-selective herbicide that widely used in many countries worldwide, but the biological safety including potentially negative effects on aquatic organisms remains largely unknown. In this study, we investigated the immunotoxic effects of Gla exposure on zebrafish embryos. Firstly, Gla markedly decreased the survival rate and caused a series of morphological malformations in a dose-dependent manner. Meanwhile, the number of macrophages and neutrophils was substantially reduced upon Gla exposure. In addition, the levels of oxidative stress were changed and the antioxidant enzyme activities such as CAT and SOD were elevated with the increase of Gla concentrations. Secondly, comparative transcriptome analysis identified 1, 366 differentially expressed genes (DEGs) including 789 up-regulated and 577 down-regulated in zebrafish embryos after Gla exposure. KEGG pathway analysis revealed that metabolic pathways such as drug metabolism-cytochrome P450 was markedly regulated and proteolysis, oxidation-reduction process, and peptidase activity were significantly enriched by the GO analysis. Besides, 55 immunity-related genes were identified in the DEGs, and we found that the genes in the metabolism, redox and immunity display an unique expression profilings by clustering analysis. Finally, 8 inflammatory cytokines and chemokines were further confirmed and they were differentially regulated after Gla exposure. In summary, a global survey of zebrafish defense against glufosinate was performed, and a large number of gene expression levels regarding metabolism, redox, and immunity-related genes were acquired from RNA-Seq. This study provides valuable informations for future elucidating the molecular mechanism of herbicide induced immunotoxicity in aquatic ecosystems.

Immunotoxic effects of lead on birds.

The ingestion of lead (Pb) shot pellets is a well-known cause of avian mortality, but exposure of birds to Pb may have other sublethal effects that can affect population sustainability. One of these effects is the alteration of the immunological status. Pb can affect most components of the avian immune system and imbalance the relationship among them. Pb exposure typically alters the ratio between Th1- and Th2-type responses mounted by different classes of T-lymphocytes, causing the depression of the Th1 responses that are associated with cell-mediated immunity. Immunodepressing effects of Pb on birds are observed at blood levels above 50 µg dL-1, but developing birds show immunodepressing effects at much lower concentrations (> 10 µg dL-1). Impacts of Pb on the avian immune system also relate to reduced resistance to infection. We review immunotoxic effects of Pb on birds affected by shot ingestion as well as by other sources of exposure to this element.

How microwave treatment of gluten affects its toxicity for celiac patients? A study on the effect of microwaves on the structure, conformation, functionality and immunogenicity of gluten.

The microwave heating of wheat kernels, flour, and gluten, has attracted attention lately because it has been claimed to abolish gluten toxicity for celiac patients. Nevertheless, contradictory results have been reported regarding the effect on gluten celiac-immunotoxicity. In order to better understand the effect of the microwave treatment on gluten structure, conformation, functionality and celiac-immunotoxicity, a central composite design with two factors, power level, and treatment time, was used to investigate a possible quadratic and interaction effects between both factors. Extractable gliadins content was affected by the power and time in a linear and quadratic fashion; extractable glutenins were not affected. Gluten secondary structure was affected by the microwave treatment and related to the polymer's disaggregation phenomenon observed. In fact, the microwave treatment increased the amount of potentially toxic epitopes released after peptic and tryptic digestion, showing inefficiency as a treatment to detoxify the gluten for celiac disease patients.

Ricin: An Ancient Story for a Timeless Plant Toxin.

The castor plant (Ricinus communis L.) has been known since time immemorial in traditional medicine in the pharmacopeia of Mediterranean and eastern ancient cultures. Moreover, it is still used in folk medicine worldwide. Castor bean has been mainly recommended as anti-inflammatory, anthelmintic, anti-bacterial, laxative, abortifacient, for wounds, ulcers, and many other indications. Many cases of human intoxication occurred accidentally or voluntarily with the ingestion of castor seeds or derivatives. Ricinus toxicity depends on several molecules, among them the most important is ricin, a protein belonging to the family of ribosome-inactivating proteins. Ricin is the most studied of this category of proteins and it is also known to the general public, having been used for several biocrimes. This manuscript intends to give the reader an overview of ricin, focusing on the historical path to the current knowledge on this protein. The main steps of ricin research are here reported, with particular regard to its enzymatic activity, structure, and cytotoxicity. Moreover, we discuss ricin toxicity for animals and humans, as well as the relation between bioterrorism and ricin and its impact on environmental toxicity. Ricin has also been used to develop immunotoxins for the elimination of unwanted cells, mainly cancer cells; some of these immunoconjugates gave promising results in clinical trials but also showed critical limitation.

Immunotoxicity of four nanoparticles to a marine bivalve species, Tegillarca granosa.

The increasing application of nanomaterials drives the unintentional release of nanoparticles (NPs) into the ocean, which may pose a potential threat to marine organisms. It has been demonstrated that exposure to NPs could chanllenge the immune responses of marine species. However, the affecting mechanism behind remains poorly understood. In this study, the immunotoxic impacts and the mechanisms underpinning the effects of four major NPs, including nZnO, nFe2O3, nCuO, and carbon nanotube (MWCNT), were investigated in blood clam, Tegillarca granosa. The results showed that exposure to tested NPs resulted in reduced total counts, altered cell composition, and constrained phagocytic activities of haemocytes. The intracellular contents of reactive oxygen species (ROS) and the degree of DNA damage of haemocytes were significantly induced, whereas the haemocyte viability was suppressed. Furthermore, NP exposures led to significant increases in the in vivo contents of neurotransmitters. Down-regulations of the immune- and neurotransmitter-related genes were detected as well. Our data suggest that NP exposures hampered the immune responses of blood clams most likely through (1) inducing ROS, causing DNA damage, and reducing cell viability of haemocytes, (2) altering the in vivo contents of neurotransmitters, and (3) affecting the expression of immune- and neurotransmitter-related genes.

Aflatoxin B1 Induces Immunotoxicity through the DNA Methyltransferase-Mediated JAK2/STAT3 Pathway in 3D4/21 Cells.

As the most toxic mycotoxin of all of the fungal toxins, aflatoxin B1 (AFB1) has carcinogenesis, heptotoxicity, and immunotoxicity. DNA methylation plays a critical role in gene expression regulation of the pathological process. However, the relationship between DNA methylation and AFB1-induced immunotoxicity was not yet reported. Therefore, the objectives of this study were to verify AFB1-induced immunotoxicity and investigate the potential role of the DNA methyltransferase (DNMT) family in AFB1-induced immunotoxicity and the pathway mechanism in 3D4/21 cells. The results showed that AFB1 could induce cytotoxicity, apoptosis, pro-inflammatory cytokine expression, DNA damage, and oxidative stress and decrease phagocytotic capacity. Meanwhile, the levels of DNMT1 and DNMT3a were significantly increased in 0.04 and 0.08 µg/mL AFB1 compared to the control. Inhibition of DNMT1 and DNMT3a by 5-Aza-2dc could reverse changes of the above parameters. Further, the JAK2/STAT3 pathway was significantly activated in 0.04 µg/mL AFB1. Inhibition of p-JAK2 and p-STAT3 by AG490 could alleviate AFB1-induced immunotoxicity. Moreover, inhibition of DNMT1 and DNMT3a by 5-Aza-2dc could suppress the phosphorylation of JAK2 and STAT3. Taken together, AFB1-induced immunotoxicity is related to the JAK2/STAT3 pathway mediated by DNMTs in 3D4/21 cells.