Haptenation: chemical reactivity and protein binding

It takes Two: Advancing cancer treatment with two-step nanoparticle delivery

The rapid advancement of nanobiotechnology has resulted in the development of numerous targeted nanoformulations and sophisticated nanobiorobots for biomedical applications. Despite the potential of nanostructures to improve drug delivery and therapeutic efficacy, their clinical application is still constrained by insufficient accumulation in tumor tissues. Current methodologies result in only an average of 0.6 % of administered nanoparticles reaching tumors, prompting the development of innovative strategies to improve targeting and influence the pharmacokinetics and pharmacodynamics of drugs. One such approach is two-step targeting, which includes either the concept of tumor pre-targeting with specific recognizing elements or the stimuli-sensitive activation of nanostructures. This review critically evaluates advancements in two-step drug delivery systems utilizing nanobiotechnology for targeted cancer therapy. For instance, two-step delivery based on the pre-targeting concept involves an initial injection of targeting molecules that bind to tumor-specific antigens, followed by the administration of drug-loaded nanocarriers modified with complementary adaptors. This approach enhances nanoparticle accumulation in tumors and improves therapeutic outcomes by increasing interaction avidity and overcoming steric hindrances. We critically assess existing adaptor systems for two-step drug delivery and synthesize findings from various studies demonstrating their efficacy in both in vitro and in vivo settings, while addressing challenges in clinical translation. We also explore future directions for developing novel adaptor systems to enhance two-step delivery mechanisms. This review aims to contribute to optimizing nanobiotechnology in oncology for more effective cancer therapies.

Rupture of Breast Implants Does Not Cause Systemic or Local Immune Changes

Breast implant rupture occurs in both saline and silicone implants, with estimated risk of rupture between 5.3% and 15.1% over a 10-year period. Concerns regarding the effect of breast implants on the immune system remain despite currently published data that does not support a link between implants, ruptured or not, and autoimmune symptoms. The authors aimed to determine if there were systemic or local immune changes caused by implant rupture. Healthy females with either ruptured or intact breast implants were recruited. Enzyme-linked immunosorbent assay (ELISA) was performed to examine systemic levels of 6 antibodies against breast-related antigens. Bulk RNA-sequencing of breast tissue adjacent to the implant was analyzed to identify differentially expressed genes (DEGs). Sixty-seven females were assessed with ELISA. Of those, 24% (16/67) had ruptured breast implants and 76% (51/67) had intact implants. There were no differences in antibody levels between intact and ruptured implants. Subgroup analyses of ruptured implants revealed no differences in antibody levels between ruptured saline and silicone implants, submuscular and subglandular implants, or textured and smooth implants. Bulk RNA-sequencing of breast tissue adjacent to ruptured implants (n = 5) and intact implants (n = 5) was performed. This revealed only 1 immune-related DEG (MS4A1), which was a downregulated gene related to B cell activation and differentiation. Rupture of breast implants was not associated with systemic changes in antibody levels or local changes in gene expression of breast parenchyma. There was no evidence for immune-related changes that might explain the autoimmune-like clinical symptoms some patients experience after implant rupture. Level of Evidence: 3 (Therapeutic).

InterDIA: Interpretable prediction of drug-induced autoimmunity through ensemble machine learning approaches

Drug-induced autoimmunity (DIA) is a non-IgE immune-related adverse drug reaction that poses substantial challenges in predictive toxicology due to its idiosyncratic nature, complex pathogenesis, and diverse clinical manifestations. To address these challenges, we developed InterDIA, an interpretable machine learning framework for predicting DIA toxicity based on molecular physicochemical properties. Multi-strategy feature selection and advanced ensemble resampling approaches were integrated to enhance prediction accuracy and overcome data imbalance. The optimized Easy Ensemble Classifier achieved robust performance in both 10-fold cross-validation (AUC value of 0.8836 and accuracy of 82.81 %) and external validation (AUC value of 0.8930 and accuracy of 85.00 %). Paired case studies of hydralazine/phthalazine and procainamide/N-acetylprocainamide demonstrated the model's capacity to discriminate between structurally similar compounds with distinct immunogenic potentials. Mechanistic interpretation through SHAP (SHapley Additive exPlanations) analysis revealed critical physicochemical determinants of DIA, including molecular lipophilicity, partial charge distribution, electronic states, polarizability, and topological features. These molecular signatures were mechanistically linked to key processes in DIA pathogenesis, such as membrane permeability and tissue distribution, metabolic bioactivation susceptibility, immune protein recognition and binding specificity. SHAP dependence plots analysis identified specific threshold values for key molecular features, providing novel insights into structure-toxicity relationships in DIA. To facilitate practical application, we developed an open-access web platform enabling batch prediction with real-time visualization of molecular feature contributions through SHAP waterfall plots. This integrated framework not only advances our mechanistic understanding of DIA pathogenesis from a molecular perspective but also provides a valuable tool for early assessment of autoimmune toxicity risk during drug development.

Chemical respiratory sensitization-Current status of mechanistic understanding, knowledge gaps and possible identification methods of sensitizers

Respiratory sensitization is a complex immunological process eventually leading to hypersensitivity following re-exposure to the chemical. A frequent consequence is occupational asthma, which may occur after long latency periods. Although chemical-induced respiratory hypersensitivity has been known for decades, there are currently no comprehensive and validated approaches available for the prospective identification of chemicals that induce respiratory sensitization, while the expectations of new approach methodologies (NAMs) are high. A great hope is that due to a better understanding of the molecular key events, new methods can be developed now. However, this is a big challenge due to the different chemical classes to which respiratory sensitizers belong, as well as because of the complexity of the response and the late manifestation of symptoms. In this review article, the current information on respiratory sensitization related processes is summarized by introducing it in the available adverse outcome pathway (AOP) concept. Potentially useful models for prediction are discussed. Knowledge gaps and gaps of regulatory concern are identified.

Efficacy of novel allogeneic cancer cells vaccine to treat colorectal cancer

Colorectal cancer (CRC) remains a significant global health burden, emphasizing the need for innovative treatment strategies. 95% of the CRC population are microsatellite stable (MSS), insensitive to classical immunotherapies such as anti-PD-1; on the other hand, responders can become resistant and relapse. Recently, the use of cancer vaccines enhanced the immune response against tumor cells. In this context, we developed a therapeutic vaccine based on Stimulated Tumor Cells (STC) platform technology. This vaccine is composed of selected tumor cell lines stressed and haptenated in vitro to generate a factory of immunogenic cancer-related antigens validated by a proteomic cross analysis with patient's biopsies. This technology allows a multi-specific education of the immune system to target tumor cells harboring resistant clones. Here, we report safety and antitumor efficacy of the murine version of the STC vaccine on CT26 BALB/c CRC syngeneic murine models. We showed that one cell line (1CL)-based STC vaccine suppressed tumor growth and extended survival. In addition, three cell lines (3CL)-based STC vaccine significantly improves these parameters by presenting additional tumor-related antigens inducing a multi-specific anti-tumor immune response. Furthermore, proteomic analyses validated that the 3CL-based STC vaccine represents a wider quality range of tumor-related proteins than the 1CL-based STC vaccine covering key categories of tumor antigens related to tumor plasticity and treatment resistance. We also evaluated the efficacy of STC vaccine in an MC38 anti-PD-1 resistant syngeneic murine model. Vaccination with the 3CL-based STC vaccine significantly improved survival and showed a confirmed complete response with an antitumor activity carried by the increase of CD8+ lymphocyte T cells and M1 macrophage infiltration. These results demonstrate the potential of this technology to produce human vaccines for the treatment of patients with CRC.

Low-cost quantum mechanical descriptors for data efficient skin sensitization QSAR models

Quantitative Structure Activity Relationship modelling methodologies need to incorporate relevant mechanistic information to have high predictive performance and validity. Electrophilic reactivity is a common mechanistic feature of skin sensitization endpoints which could be concisely characterized with electronic descriptors which is key to enabling the modelling of small datasets in this domain. However, quantum mechanical methodologies have previously featured high computational costs which would exclude the use of large datasets. Consequently, we investigate the use of electronic descriptors calculated using the Hartree Fock with 3 corrections (Hf-3c) method, a low-cost ab initio methodology that has higher chemical accuracy than previous semiempirical methodologies for modelling in vitro skin sensitization assay outcomes. We also model the Ames assay as a surrogate for determining skin sensitization outcomes. The quantum chemical descriptors calculated using the Hf-3c method with conductor-like polarizable continuum model (CPCM) implicit solvation found improved QSAR model performance for the in vitro Ames (n = 6049, 0.770 AUC), KeratinoSens (n = 164, 0.763 AUC), and Direct Peptide Reactivity Assay (n = 122, 0.750 AUC) datasets, with their combination producing high predictive performance for unseen in vivo Local Lymph Node Assay (n = 86, 0.789 AUC) and Human Repeated Insult Patch Test (n = 86, 0.791 AUC) assay toxicant outcomes.

Perioperative Anaphylaxis in Japanese Secondary Care Institutions: Incidence, Causes, and the Imperative for Improved Diagnostic Practices

Background This research investigates the incidence, suspected causes, and diagnostic procedures for perioperative anaphylaxis (POA), a potentially severe complication, in secondary care hospitals across Japan. Methodology We surveyed Saiseikai hospitals and gathered data on surgical procedures, POA occurrences, potential triggers, and diagnostic methods. Results Among 70,523 surgeries, seven were associated with POA, resulting in an approximate incidence rate of 0.01%. Rocuronium was the most commonly suspected trigger, followed by sugammadex, latex, and angiography contrast agents. Despite the importance of skin tests as the most basic and crucial diagnostic method, they were conducted in only three instances. No in vitro tests for drug identification were conducted, and in four cases, the cause was determined merely based on the timing of drug administration, indicating significant diagnostic limitations. Conclusions The study underscores the critical situation in Japan regarding insufficient diagnostic practices and difficulties in identifying triggering drugs rather than the consistent prevalence of POA in secondary care facilities. The findings emphasize the need for improved diagnostic proficiency and more rigorous drug identification practices to ensure prompt and accurate POA diagnosis. It is essential to conduct further research and interventions to increase patient safety during the perioperative period in secondary care settings.

Circular economyeast: Saccharomyces cerevisiae as a sustainable source of glucans and its safety for skincare application

Glucans, a polysaccharide naturally present in the yeast cell wall that can be obtained from side streams generated during the fermentation process, have gained increasing attention for their potential as a skin ingredient. Therefore, this study focused on the extraction method to isolate and purify water-insoluble glucans from two different Saccharomyces cerevisiae strains: an engineered strain obtained from spent yeast in an industrial fermentation process and a wild strain produced through lab-scale fermentation. Two water-insoluble extracts with a high glucose content (> 90 %) were achieved and further subjected to a chemical modification using carboxymethylation to improve their water solubility. All the glucans' extracts, water-insoluble and carboxymethylated, were structurally and chemically characterized, showing almost no differences between both yeast-type strains. To ensure their safety for skin application, a broad safety assessment was undertaken, and no cytotoxic effect, immunomodulatory capacity (IL-6 and IL-8 regulation), genotoxicity, skin sensitization, and impact on the skin microbiota were observed. These findings highlight the potential of glucans derived from spent yeast as a sustainable and safe ingredient for cosmetic and skincare formulations, contributing to the sustainability and circular economy.

Mass spectrometry-based methods to characterize highly heterogeneous biopharmaceuticals, vaccines, and nonbiological complex drugs at the intact-mass level

The intact-mass MS measurements are becoming increasingly popular in characterization of a range of biopolymers, especially those of interest to biopharmaceutical industry. However, as the complexity of protein therapeutics and other macromolecular medicines increases, the new challenges arise, one of which is the high levels of structural heterogeneity that are frequently exhibited by such products. The very notion of the molecular mass measurement loses its clear and intuitive meaning when applied to an extremely heterogenous system that cannot be characterized by a unique mass, but instead requires that a mass distribution be considered. Furthermore, convoluted mass distributions frequently give rise to unresolved ionic signal in mass spectra, from which little-to-none meaningful information can be extracted using standard approaches that work well for homogeneous systems. However, a range of technological advances made in the last decade, such as the hyphenation of intact-mass MS measurements with front-end separations, better integration of ion mobility in MS workflows, development of an impressive arsenal of gas-phase ion chemistry tools to supplement MS methods, as well as the revival of the charge detection MS and its triumphant entry into the field of bioanalysis already made impressive contributions towards addressing the structural heterogeneity challenge. An overview of these techniques is accompanied by critical analysis of the strengths and weaknesses of different approaches, and a brief overview of their applications to specific classes of biopharmaceutical products, vaccines, and nonbiological complex drugs.

A human 3D immune competent full-thickness skin model mimicking dermal dendritic cell activation

We have integrated dermal dendritic cell surrogates originally generated from the cell line THP-1 as central mediators of the immune reaction in a human full-thickness skin model. Accordingly, sensitizer treatment of THP-1-derived CD14-, CD11c+ immature dendritic cells (iDCs) resulted in the phosphorylation of p38 MAPK in the presence of 1-chloro-2,4-dinitrobenzene (DNCB) (2.6-fold) as well as in degradation of the inhibitor protein kappa B alpha (IκBα) upon incubation with NiSO4 (1.6-fold). Furthermore, NiSO4 led to an increase in mRNA levels of IL-6 (2.4-fold), TNF-α (2-fold) and of IL-8 (15-fold). These results were confirmed on the protein level, with even stronger effects on cytokine release in the presence of NiSO4: Cytokine secretion was significantly increased for IL-8 (147-fold), IL-6 (11.8-fold) and IL-1β (28.8-fold). Notably, DNCB treatment revealed an increase for IL-8 (28.6-fold) and IL-1β (5.6-fold). Importantly, NiSO4 treatment of isolated iDCs as well as of iDCs integrated as dermal dendritic cell surrogates into our full-thickness skin model (SM) induced the upregulation of the adhesion molecule clusters of differentiation (CD)54 (iDCs: 1.2-fold; SM: 1.3-fold) and the co-stimulatory molecule and DC maturation marker CD86 (iDCs ~1.4-fold; SM:~1.5-fold) surface marker expression. Noteworthy, the expression of CD54 and CD86 could be suppressed by dexamethasone treatment on isolated iDCs (CD54: 1.3-fold; CD86: 2.1-fold) as well as on the tissue-integrated iDCs (CD54: 1.4-fold; CD86: 1.6-fold). In conclusion, we were able to integrate THP-1-derived iDCs as functional dermal dendritic cell surrogates allowing the qualitative identification of potential sensitizers on the one hand, and drug candidates that potentially suppress sensitization on the other hand in a 3D human skin model corresponding to the 3R principles ("replace", "reduce" and "refine").

Applicability of the DPRA on mixture testing: challenges and opportunities

The in chemico direct peptide reactivity assay (DPRA) is validated to assess protein reactivity of chemical compounds, relating to the molecular initiating event of skin sensitization induction. According to OECD TG 442C, the DPRA is technically applicable to test multi-constituent substances and mixtures of known composition, even though limited experimental data are publicly available. First, we assessed the DPRA's predictive capability for individual substances, but at concentrations other than the recommended 100 mM, i.e., based on the LLNA EC3 concentration (Experiment A). Next, the applicability of the DPRA to test unknown mixtures was assessed (Experiment B). Here, the complexity of unknown mixtures was reduced to mixtures containing either two known skin sensitizers with varying potencies, or a combination of a skin sensitizer with a non-skin sensitizer, or multiple non-sensitizers. Experiments A and B revealed that one extremely potent sensitizer (oxazolone) was incorrectly classified as a non-sensitizer when tested at its low EC3 concentration of 0.4 mM instead of the suggested molar excess conditions of 100 mM (Experiments A). For binary mixtures tested in experiments B, the DPRA was able to distinguish all skin sensitizers and the strongest skin sensitizer in the mixture was determinant for the overall peptide depletion of a sensitizer. In conclusion, we confirmed that the DPRA test method can be used efficiently for well-known characterized mixtures. However, when deviating from the recommended testing concentration of 100 mM, caution should be taken in case of negative results, limiting the DPRA's applicability for mixtures of unknown composition.

When the allergy alarm bells toll: The role of Toll-like receptors in allergic diseases and treatment

Toll-like receptors of the human immune system are specialized pathogen detectors able to link innate and adaptive immune responses. TLR ligands include among others bacteria-, mycoplasma- or virus-derived compounds such as lipids, lipo- and glycoproteins and nucleic acids. Not only are genetic variations in TLR-related genes associated with the pathogenesis of allergic diseases, including asthma and allergic rhinitis, their expression also differs between allergic and non-allergic individuals. Due to a complex interplay of genes, environmental factors, and allergen sources the interpretation of TLRs involved in immunoglobulin E-mediated diseases remains challenging. Therefore, it is imperative to dissect the role of TLRs in allergies. In this review, we discuss i) the expression of TLRs in organs and cell types involved in the allergic immune response, ii) their involvement in modulating allergy-associated or -protective immune responses, and iii) how differential activation of TLRs by environmental factors, such as microbial, viral or air pollutant exposure, results in allergy development. However, we focus on iv) allergen sources interacting with TLRs, and v) how targeting TLRs could be employed in novel therapeutic strategies. Understanding the contributions of TLRs to allergy development allow the identification of knowledge gaps, provide guidance for ongoing research efforts, and built the foundation for future exploitation of TLRs in vaccine design.

Heavy metals in contact dermatitis: A review

Contact dermatitis is an inflammatory skin reaction caused by direct contact with chemical substances in the environment and can either be irritant or allergic in nature. The clinical symptoms of contact dermatitis, include local skin rash, itching, redness, swelling, and lesions. Nowadays, 15-20% of people have some degree of contact dermatitis, which can be more or less severe. Immune responses in allergic contact dermatitis (ACD) are due to the effects of cytokines and allergen-specific CD4⁺ and CD8⁺ T cells on the skin. Acids and alkalis such as drain cleaners, plants such as poinsettias, hair colors, and nail polish remover, are all prominent causes of irritant contact dermatitis (ICDs). Heavy metals are metallic elements with a high atomic weight that are hazardous in low quantities and are known to cause dermatitis after systemic or local exposure. Nickel (Ni), chromium (Cr), lead (Pb), and copper (Cu) are among the most common heavy metals used in various industries. Metal allergies may cause ACD and also systemic contact dermatitis (SCD). Contact dermatitis is detected by laboratory tests such as patch testing, lymphocyte stimulation test (LST), and evaluation of cytokine production by primary cultures of peripheral blood mononuclear cells. This article presents an update on the epidemiological and clinical characteristics of ACD and SCD caused by three heavy metals (Cr, Cu, and Pb). Ni is not discussed due to recent coverage. Furthermore, the effects of contact sensitivity to some other heavy metals, such as gold (Au), cobalt (Co), palladium (Pd), and mercury (Hg) are discussed.

Awaken Immune Cells by Hapten Enhanced Intratumoral Chemotherapy with Penicillin Prolong Pancreatic Cancer Survival

Intratumoral immunotherapy is well studied and is ongoing, but few studies have evaluated the relationship between of cytotoxic drugs intratumoral injection (CDI) and hapten-enhanced cytotoxic drugs intratumoral injection (HECDI) and patient survival. The objectives of this study include comparisons to explore possible associations between the proportions of treatment-induced cytokines and autologous antibodies to tumor-associated antigens (TAAs) and the relative size of the abscopal effects concurring. CDIs contain oxidant and cytotoxic drugs, HECDIs contains the same drug plus penicillin as the new Hapten. Of the 33 patients with advanced pancreatic cancer, 9 received CDI, 20 received HECDI, and 4 (control group) received placebo. Serum levels of cytokines and autoantibodies of TAAs were detected and compared after therapy. The 1-year survival rate was 11.11% for CDI and 52.63% for HECDI (P= 0.035). In the general analysis of cytokines, HECDI exhibited an increasing level of IFN-γ and IL-4, and the non-hapten CDI showed a rising level of IL-12 (P = 0.125, 0.607, & 0.04). Participants who did not receive chemotherapy had significant differences in the level of Zeta autoantibody only before and after HECDI; However, IMP1 levels in patients with previous chemotherapy experience were significantly different before and after HECDI and CDI treatment (P≤0.05, P = 0.316). After HECDI treatment, TAA autoantibodies of RalA, Zeta, HCC1, p16 increased (P = 0.429, 0.416, 0.042, 0.112). The elevated levels of CXCL8, IFN-γ, HCC1, RalA, Zeta, and p16 observed in HECDI may be attributed to the abscopal effect (P = 0.012 & 0.013). Overall survival rates indicated that HECDI treatment extended participants' lives.

The Skin Sensitisation of Cosmetic Ingredients: Review of Actual Regulatory Status

All cosmetics products must be safe under foreseeable conditions of use. Allergenic responses are one of the most frequent adverse reactions noted for cosmetics. Thus, the EU cosmetics legislation requires skin sensitisation assessment for all cosmetics ingredients, including the regulated ones (for which the full toxicological dossier needs to be analysed by the Scientific Committee on Consumer Safety (SCCS)) and those (perceived as less toxic) which are assessed by industrial safety assessors. Regardless of who performs the risk assessment, it should be carried out using scientifically and regulatory body-accepted methods. In the EU, reference methods for chemical toxicity testing are defined in the relevant Annexes (VII-X) of the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) Regulation. Recommendations for Skin Sensitization (Skin Sens) testing are provided in Annex VII, and this particular endpoint information is required for all EU-registered chemicals. Historically, in vivo animal and human methods have been used. Both raise ethical doubts, and some of them cause practical problems in the objective analysis of skin sensitising potency. Previous decades of huge effort have resulted in the regulatory acceptance of the alternative Skin Sens IATA (Integrated Approaches to Testing and Assessment) and NGRA (Next Generation Risk Assessment). Regardless of the testing issues, a serious sociological problem are observed within the market: the consumer assumes the presence of strong sensitisers in cosmetics formulations and insufficient risk management tools used by the industry. The present review aims to provide an overview of methods for assessing skin sensitisation. Additionally, it aims to answer the following question: what are the most potent skin sensitisers used in cosmetics? The answer considers the mechanistic background along with the actual regulatory status of ingredients and practical examples of responsible industry solutions in the area of risk management.

Monocarbonyl Analogs of Curcumin with Potential to Treat Colorectal Cancer

Curcumin has a plethora of biological properties, making this compound potentially effective in the treatment of several diseases, including cancer. However, curcumin clinical use is compromised by its poor pharmacokinetics, being crucial to find novel analogs with better pharmacokinetic and pharmacological properties. Here, we aimed to evaluate the stability, bioavailability and pharmacokinetic profiles of monocarbonyl analogs of curcumin. A small library of monocarbonyl analogs of curcumin 1a-q was synthesized. Lipophilicity and stability in physiological conditions were both assessed by HPLC-UV, while two different methods assessed the electrophilic character of each compound monitored by NMR and by UV-spectroscopy. The potential therapeutic effect of the analogs 1a-q was evaluated in human colon carcinoma cells and toxicity in immortalized hepatocytes. Our results showed that the curcumin analog 1e is a promising agent against colorectal cancer, with improved stability and efficacy/safety profile.

Chemical- and Drug-Induced Allergic, Inflammatory, and Autoimmune Diseases Via Haptenation

Haptens are small molecules that only elicit an immune response when bound to proteins. Haptens initially bind to self-proteins and activate innate immune responses by complex mechanisms via inflammatory cytokines and damage-associated molecular patterns and the subsequent upregulation of costimulatory signals such as cluster of differentiation 86 (CD86) on dendritic cells. Subsequent interactions between CD86 and CD28 on T cells are critically important for properly activating naive T cells and inducing interleukin 2 production, leading to the establishment of adaptive immunity via effector and memory T cells. Accumulating evidence revealed the involvement of haptens in the development of various autoimmune-like diseases such as allergic, inflammatory, and autoimmune diseases including allergic contact dermatitis, atopy, asthma, food allergy, inflammatory bowel diseases, hemolytic anemia, liver injury, leukoderma, and even antitumor immunity. Therefore, the development of in vitro testing alternatives to evaluate in advance whether a substance might lead to the development of these diseases is highly desirable. This review summarizes and discusses recent advances in chemical- and drug-induced allergic, inflammatory, and autoimmune diseases via haptenation and the possible molecular underlying mechanisms, as well as in vitro testing alternatives to evaluate in advance whether a substance might cause the development of these diseases.

Assessing the skin irritation and sensitizing potential of concentrates of water chlorinated in the presence of iodinated X-ray contrast media

Chemical disinfection of water provides significant public health benefits. However, disinfectants like chlorine can react with naturally occurring materials in the water to form disinfection byproducts (DBPs). Natural levels of iodine have been reported to be too low in some source waters to account for the levels of iodinated DBPs detected. Iodinated X-ray contrast media (ICM) have been identified as a potential source of iodine. The toxicological impact of ICM present in source water at the time of disinfection has not been fully investigated. Iopamidol, iohexol, iopromide, and diatrizoate are among the ICM most frequently detected in water. In this study, source water containing one of these four ICM was chlorinated; non-chlorinated ICM-containing water samples served as controls. Reactions were conducted at an ICM concentration of 5 µM and a chlorine dose of 100 µM over 72 hr. Water concentrates (20,000-fold) were prepared by XAD-resin/ethyl acetate extraction and DMSO solvent exchange. We used the MatTek® reconstituted human epithelial skin irritation model to evaluate the water concentrates and also assessed the dermal irritation and sensitization potential of these concentrates using the LLNA:BrdU ELISA in BALB/c mice. None of the water concentrates tested (2500X) resulted in a skin irritant response in the MatTek® skin irritation model. Likewise, none of the concentrates (2500X, 1250X, 625X, 312.5X, 156.25X) produced a skin irritation response in mice: erythema was minimal; the maximum increase in ear thickness was less than 25%. Importantly, none of the concentrates produced a positive threshold response for allergic skin sensitization at any concentration tested in the LLNA:BrdU ELISA. We conclude that concentrates of water disinfected in the presence of four different ICM did not cause significant skin irritation or effects consistent with skin sensitization at the concentrations tested.

The correlation of haptenation of gold nanoparticles and cysteine modified screen printed carbon electrode by impedance technique with local lymph node assay data

Skin sensitization occurs when a skin sensitizer binds covalently to skin proteins through the haptenation process. The objective of this study was to correlate the electrochemical impedance spectroscopy (EIS) data of a screen printed carbon electrode (SPCE) modified with cysteine and gold nanoparticles (AuNPs) with local lymph node assay (LLNA) data as a potential skin sensitizer biosensor. The EIS was used to quantify variations in charge transfer resistance of skin sensitizers (ΔR_CT^{skin sensitizer}) due to different binding rates of skin sensitizers to cysteine. SPCE was modified through electrodeposition of AuNPs/thiourea/self-assembly of AuNPs/cysteine (assigned as ETSC) for the detection of skin sensitizers. Surface analysis of modified SPCEs using FESEM and EDX revealed a smooth surface with an uneven distribution of cysteine with AuNPs molecules. The ETSC modified SPCE showed a significant skin sensitizer biosensor since the ΔR_CT^{skin sensitizer} readings were increased proportionally to the strength of the skin sensitizers, with strong/extreme skin sensitizers displaying higher ΔR_CT^{skin sensitizer} readings compared to moderate and weak/non-skin sensitizers. The skin sensitization analysis from this work was compared to LLNA (animal study), human cell line activation (h-CLAT), direct peptide reactivity assay (DPRA), and KeratinoSens™, surface plasmon resonance (SPR) matched the categorization of LLNA in the following descending order: 96%, 92%, 82%, 70%, 70%, and 12%. With just an 8% mismatch with LLNA data, the EIS approach used in this study could be used as a screening tool for skin sensitizers.

Topical therapy for regression and melanoma prevention of congenital giant nevi

Giant congenital melanocytic nevi are NRAS-driven proliferations that may cover up to 80% of the body surface. Their most dangerous consequence is progression to melanoma. This risk often triggers preemptive extensive surgical excisions in childhood, producing severe lifelong challenges. We have presented preclinical models, including multiple genetically engineered mice and xenografted human lesions, which enabled testing locally applied pharmacologic agents to avoid surgery. The murine models permitted the identification of proliferative versus senescent nevus phases and treatments targeting both. These nevi recapitulated the histologic and molecular features of human giant congenital nevi, including the risk of melanoma transformation. Cutaneously delivered MEK, PI3K, and c-KIT inhibitors or proinflammatory squaric acid dibutylester (SADBE) achieved major regressions. SADBE triggered innate immunity that ablated detectable nevocytes, fully prevented melanoma, and regressed human giant nevus xenografts. These findings reveal nevus mechanistic vulnerabilities and suggest opportunities for topical interventions that may alter the therapeutic options for children with congenital giant nevi.

In Vitro Monitoring of Human T Cell Responses to Skin Sensitizing Chemicals-A Systematic Review

Background: Chemical allergies are T cell-mediated diseases that often manifest in the skin as allergic contact dermatitis (ACD). To prevent ACD on a public health scale and avoid elicitation reactions at the individual patient level, predictive and diagnostic tests, respectively, are indispensable. Currently, there is no validated in vitro T cell assay available. The main bottlenecks concern the inefficient generation of T cell epitopes and the detection of rare antigen-specific T cells. Methods: Here, we systematically review original experimental research papers describing T cell activation to chemical skin sensitizers. We focus our search on studies published in the PubMed and Scopus databases on non-metallic allergens in the last 20 years. Results: We identified 37 papers, among them 32 (86%) describing antigen-specific human T cell activation to 31 different chemical allergens. The remaining studies measured the general effects of chemical allergens on T cell function (five studies, 14%). Most antigen-specific studies used peripheral blood mononuclear cells (PBMC) as antigen-presenting cells (APC, 75%) and interrogated the blood T cell pool (91%). Depending on the individual chemical properties, T cell epitopes were generated either by direct administration into the culture medium (72%), separate modification of autologous APC (29%) or by use of hapten-modified model proteins (13%). Read-outs were mainly based on proliferation (91%), often combined with cytokine secretion (53%). The analysis of T cell clones offers additional opportunities to elucidate the mechanisms of epitope formation and cross-reactivity (13%). The best researched allergen was p-phenylenediamine (PPD, 12 studies, 38%). For this and some other allergens, stronger immune responses were observed in some allergic patients (15/31 chemicals, 48%), illustrating the in vivo relevance of the identified T cells while detection limits remain challenging in many cases. Interpretation: Our results illustrate current hardships and possible solutions to monitoring T cell responses to individual chemical skin sensitizers. The provided data can guide the further development of T cell assays to unfold their full predictive and diagnostic potential, including cross-reactivity assessments.

Skin Sensitization Potential and Cellular ROS-Induced Cytotoxicity of Silica Nanoparticles

Nowadays, various industries using nanomaterials are growing rapidly, and in particular, as the commercialization and use of nanomaterials increase in the cosmetic field, the possibility of exposure of nanomaterials to the skin of product producers and consumers is increasing. Due to the unique properties of nanomaterials with a very small size, they can act as hapten and induce immune responses and skin sensitization, so accurate identification of toxicity is required. Therefore, we selected silica nanomaterials used in various fields such as cosmetics and biomaterials and evaluated the skin sensitization potential step-by-step according to in-vitro and in-vivo alternative test methods. KeratinoSens^TM cells of modified keratinocyte and THP-1 cells mimicking dendritic-cells were treated with silica nanoparticles, and their potential for skin sensitization and cytotoxicity were evaluated, respectively. We also confirmed the sensitizing ability of silica nanoparticles in the auricle-lymph nodes of BALB/C mice by in-vivo analysis. As a result, silica nanoparticles showed high protein binding and reactive oxygen species (ROS) mediated cytotoxicity, but no significant observation of skin sensitization indicators was observed. Although more studies are needed to elucidate the mechanism of skin sensitization by nanomaterials, the results of this study showed that silica nanoparticles did not induce skin sensitization.

Chemical Modifications Induced by Phthalic Anhydride, a Respiratory Sensitizer, in Reconstructed Human Epidermis: A Combined HRMAS NMR and LC-MS/MS Proteomic Approach

Chemical skin and respiratory allergies are becoming a major health problem. To date our knowledge on the process of protein haptenation is still limited and mainly derived from studies performed in solution using model nucleophiles. In order to better understand chemical interactions between chemical allergens and the skin, we have investigated the reactivity of phthalic anhydride 1 (PA), a chemical respiratory sensitizer, toward reconstructed human epidermis (RHE). This study was performed using a new approach combining HRMAS NMR to investigate the in situ chemical reactivity and LC-MS/MS to identify modified epidermal proteins. In RHE, the reaction of PA appeared to be quite fast and the major product formed was phthalic acid. Two amide type adducts on lysine residues were observed and after 8h of incubation, we also observed the formation of an imide type cyclized adducts with lysine. In parallel, RHE samples topically exposed to phthalic anhydride (¹³C)-1 were analyzed using the shotgun proteomics method. Thus, 948 different proteins were extracted and identified, 135 of which being modified by PA, i.e., 14.2% of the extracted proteome. A total of 211 amino acids were modified by PA and validated by fragmentation spectra. We thus identified 154 modified lysines, 22 modified histidines, 30 modified tyrosines, and 5 modified arginines. The rate of modified residues, as a proportion of the total number of modifiable nucleophilic residues in RHE, was rather low (1%). At the protein level, modified proteins were mainly type I and type II keratins and other proteins which are abundant in the epidermis such as protein S100A, Caspase 14, annexin A2, serpin B3, fatty-acid binding protein 5, histone H2, H3, H4, etc. However, the most modified protein, mainly on histidine residues, was filaggrin, a protein that is of low abundance (0.0266 mol %) and rich in histidine.

Simultaneous Evaluation of a Vaccine Component Microheterogeneity and Conformational Integrity Using Native Mass Spectrometry and Limited Charge Reduction

Analytical characterization of extensively modified proteins (such as haptenated carrier proteins in synthetic vaccines) remains a challenging task due to the high degree of structural heterogeneity. Native mass spectrometry (MS) combined with limited charge reduction allows these obstacles to be overcome and enables meaningful characterization of a heavily haptenated carrier protein CRM197 (inactivated diphtheria toxin conjugated with nicotine), a major component of a smoking cessation vaccine. The extensive conjugation results in a near-continuum distribution of ionic signal in electrospray ionization (ESI) mass spectra of haptenated CRM197 even after size-exclusion chromatographic fractionation. However, supplementing the ESI MS measurements with limited charge reduction of ionic populations selected within narrow m/z windows gives rise to well-resolved charge ladders, from which both masses and charge states of the ionic species can be readily deduced. Application of this technique to a research-grade material of CRM197/H7 conjugate not only reveals its marginal conformational stability (manifested by the appearance of high charge-density ions in ESI MS) but also establishes a role of the extent of haptenation as a major factor driving the loss of the higher order structure integrity. The unique information provided by native MS used in combination with limited charge reduction provides a strong argument for this technique to become a standard/required tool in the analytical arsenal in the field of biotechnology and biopharmaceutical analysis, where protein conjugates are becoming increasingly common.

Potential classification of chemical immunologic response based on gene expression profiles

Occupational immune diseases are a serious public health burden and are often a result of exposure to low molecular weight (LMW) chemicals. The complete immunological mechanisms driving these responses are not fully understood which has made the classification of chemical allergens difficult. Antimicrobials are a large group of immunologically-diverse LMW agents. In these studies, mice were dermally exposed to representative antimicrobial chemicals (sensitizers: didecyldimethylammonium chloride (DDAC), ortho-phthalaldehyde (OPA), irritants: benzal-konium chloride (BAC), and adjuvant: triclosan (TCS)) and the mRNA expression of cytokines and cellular mediators was evaluated using real-time qPCR in various tissues over a 7-days period. All antimicrobials caused increases in the mRNA expression of the danger signals Tslp (skin), and S100a8 (skin, blood, lung). Expression of the T_H2 cytokine Il4 peaked at different timepoints for the chemicals based on exposure duration. Unique expression profiles were identified for OPA (Il10 in lymph node, Il4 and Il13 in lung) and TCS (Tlr4 in skin). Additionally, all chemicals except OPA induced decreased expression of the cellular adhesion molecule Ecad. Overall, the results from these studies suggest that unique gene expression profiles are implicated following dermal exposure to various antimicrobial agents, warranting the need for additional studies. In order to advance the development of preventative and therapeutic strategies to combat immunological disease, underlying mechanisms of antimicrobial-induced immunomodulation must be fully understood. This understanding will aid in the development of more effective methods to screen for chemical toxicity, and may potentially lead to more effective treatment strategies for those suffering from immune diseases.

Future perspectives on in-vitro diagnosis of drug allergy by the lymphocyte transformation test

This article aims to envisage future perspectives of the lymphocyte transformation test (LTT). We describe the select innovative techniques, which can be integrated at different stages of the LTT to potentially improve the sensitivity, specificity, or practicability of the LTT. We first focus upon the cell sorting techniques comprising immunomagnetic cell separation and flow cytometry, which can be implemented prior and after the LTT culturing step to concentrate and quantify specific immune cell types. Further, we elaborate upon three important omics techniques such as transcriptomics, proteomics, and metabolomics, which can be integrated downstream of the LTT to analyze molecular changes in specific immune cells following drug induced activation and proliferation. We also develop visions, how state of the art techniques used in other scientific fields, can be transferred and applied in the context of in-vitro detection of drug allergy.

Allergic contact dermatitis: From pathophysiology to development of new preventive strategies

As the body's first line of defense, the skin is the organ most frequently exposed to chemicals present in personal hygiene products, household products, or materials used in the work environment. In this context, skin disorders account for more than 40 % of all occupational and work-related diseases, constituting a significant public health burden. Among skin disorders, allergic contact dermatitis (ACD) is the most prevalent occupational disease and the most common form of immunotoxicity in humans. ACD is a T-cell-mediated skin inflammation resulting from the priming and expansion of allergen-specific CD4⁺ and CD8⁺ T cells. The clinical condition is characterized by local skin rash, itchiness, redness, swelling, and lesions, being mainly diagnosed by the patch test. Upon ACD diagnosis, avoiding the exposure to the triggering allergen is the mainstay of treatment to prevent future flares. In cases where avoidance is not possible, the use of a standard of care interim treatments such as steroid creams or ointments, barrier creams, and moisturizers are strongly recommended to alleviate symptoms. In this review, we sought to provide the reader with an overview of the pathophysiology of ACD as well as the currently available pharmacological treatment options. Furthermore, a comprehensive outline of several preventive strategies is also provided.

Cross-Reactivity between Chemical Antibodies Formed to Serum Proteins and Thyroid Axis Target Sites

In some instances, when chemicals bind to proteins, they have the potential to induce a conformational change in the macromolecule that may misfold in such a way that makes it similar to the various target sites or act as a neoantigen without conformational change. Cross-reactivity then can occur if epitopes of the protein share surface topology to similar binding sites. Alteration of peptides that share topological equivalence with alternating side chains can lead to the formation of binding surfaces that may mimic the antigenic structure of a variant peptide or protein. We investigated how antibodies made against thyroid target sites may bind to various chemical–albumin compounds where binding of the chemical has induced human serum albumin (HSA) misfolding. We found that specific monoclonal or polyclonal antibodies developed against thyroid-stimulating hormone (TSH) receptor, 5′-deiodinase, thyroid peroxidase, thyroglobulin, thyroxine-binding globulin (TBG), thyroxine (T4), and triiodothyronine (T3) bound to various chemical HSA compounds. Our study identified a new mechanism through which chemicals bound to circulating serum proteins lead to structural protein misfolding that creates neoantigens, resulting in the development of antibodies that bind to key target proteins of the thyroid axis through protein misfolding. For demonstration of specificity of thyroid antibody binding to various haptenic chemicals bound to HSA, both serial dilution and inhibition studies were performed and proportioned to the dilution. A significant decline in these reactions was observed. This laboratory analysis of immune reactivity between thyroid target sites and chemicals bound to HSA antibodies identifies a new mechanism by which chemicals can disrupt thyroid function.

NLRP3 Inflammasome and Allergic Contact Dermatitis: A Connection to Demystify

Allergic contact dermatitis is a common occupational disease that manifests as a cell-mediated hypersensitivity reaction following skin exposure to small reactive chemicals termed haptens. Haptens penetrate the stratum corneum and covalently modify proteins in the epidermis, inducing intracellular stress, which further leads to the release of damage-associated molecular patterns (DAMPs), such as uric acid, reactive oxygen species, hyaluronic acid fragments and extracellular adenosine triphosphate (ATP). These DAMPs are recognized by pattern recognition receptors (PRRs) in innate immune cells, namely dendritic cells (DCs), leading to their maturation and migration to the draining lymph nodes where they activate naïve T lymphocytes. Among all PRRs, several studies emphasize the role of NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammasome on the allergic contact dermatitis (ACD) sensitization phase. However, skin allergens-danger signals-NLRP3 inflammasome axis is yet to be completely elucidated. Therefore, in this review, we sought to discuss the molecular mechanisms underlying DAMPs release and NLRP3 inflammasome activation triggered by skin allergens. The elucidation of these key events might help to identify novel therapeutic strategies for ACD, as well as the development of nonanimal alternative methods for the identification and potency categorization of skin sensitizers.

Bioactivation of diclofenac in human hepatocytes and the proposed human hepatic proteins modified by reactive metabolites

To reveal putative bioactivation pathways of diclofenac, in vitro human liver materials such as microsomal fractions and hepatocytes were used to confirm metabolic activation of diclofenac by ³⁵S-cysteine trapping assay and covalent binding assay. Candidate human liver proteins possibly targeted by ¹⁴C-diclofenac via bioactivation were investigated using two-dimensional gel electrophoresis followed by detection of remaining radioactivity on the modified proteins with bio-imaging analyzer.In the ³⁵S-cysteine trapping assay, three and two adducts with ³⁵S-cysteine were observed in NADPH-fortified and UDPGA-fortified human liver microsomes, respectively. In the covalent binding assay using ¹⁴C-diclofenac in human hepatocytes, the extent of covalent binding of diclofenac to human hepatic proteins increased time-dependently. Addition of glutathione attenuated the extent of covalent binding of ¹⁴C-diclofenac to human liver microsomal proteins.Fifty-nine proteins from human hepatocytes were proposed as the candidate proteins targeted by reactive metabolites of diclofenac. Proteins modified by cytochrome P450-mediated reactive metabolites were identified by using a cytochrome P450 inhibitor, 1-aminobenzyltriazole and seven of the nine radioactive protein spots were removed by 1-aminobenzyltriazole treatment.In contrast, the remaining two radioactive protein spots, mainly containing human serum albumin and heat shock proteins, were not affected by the addition of 1-aminobenzyltriazole, which suggested the involvement of the acyl glucuronide of diclofenac, formed via uridine diphosphate-glucuronosyl transferases, in the covalent modifications induced by diclofenac.

Advances in chemistry and bioactivity of parthenolide

(−)-Parthenolide is a germacrane sesquiterpene lactone, available in ample amounts from the traditional medical plant feverfew (Tanacetum parthenium).

Metal nanomaterials: Immune effects and implications of physicochemical properties on sensitization, elicitation, and exacerbation of allergic disease

The recent surge in incorporation of metallic and metal oxide nanomaterials into consumer products and their corresponding use in occupational settings have raised concerns over the potential for metals to induce size-specific adverse toxicological effects. Although nano-metals have been shown to induce greater lung injury and inflammation than their larger metal counterparts, their size-related effects on the immune system and allergic disease remain largely unknown. This knowledge gap is particularly concerning since metals are historically recognized as common inducers of allergic contact dermatitis, occupational asthma, and allergic adjuvancy. The investigation into the potential for adverse immune effects following exposure to metal nanomaterials is becoming an area of scientific interest since these characteristically lightweight materials are easily aerosolized and inhaled, and their small size may allow for penetration of the skin, which may promote unique size-specific immune effects with implications for allergic disease. Additionally, alterations in physicochemical properties of metals in the nano-scale greatly influence their interactions with components of biological systems, potentially leading to implications for inducing or exacerbating allergic disease. Although some research has been directed toward addressing these concerns, many aspects of metal nanomaterial-induced immune effects remain unclear. Overall, more scientific knowledge exists in regards to the potential for metal nanomaterials to exacerbate allergic disease than to their potential to induce allergic disease. Furthermore, effects of metal nanomaterial exposure on respiratory allergy have been more thoroughly-characterized than their potential influence on dermal allergy. Current knowledge regarding metal nanomaterials and their potential to induce/exacerbate dermal and respiratory allergy are summarized in this review. In addition, an examination of several remaining knowledge gaps and considerations for future studies is provided.

Application of the direct peptide reactivity assay (DPRA) to inorganic compounds: a case study of platinum species

The in chemico Direct Peptide Reactivity Assay (DPRA) was developed as a non-animal, relatively high throughput, screening tool for skin sensitization potential. Although the Adverse Outcome Pathway (AOP) for respiratory sensitization remains to be fully elucidated, it is recognized that the molecular initiation event for both skin and respiratory sensitization to low molecular weight chemicals involves haptenation with proteins. The DPRA examines the reactivity of a test compound to two model peptides (containing either cysteine or lysine) and consequently is able to screen for both skin and respiratory sensitization potential. The DPRA was primarily developed for and validated with organic compounds and assessment of the applicability of the assay to metal compounds has received only limited attention. This paper reports the successful application of the DPRA to a series of platinum compounds, including hexachloroplatinate and tetrachloroplatinate salts, which are some of the most potent chemical respiratory sensitizers known. Eleven platinum compounds were evaluated using the DPRA protocol as detailed by Lalko et al., with only minor modification. Two palladium compounds with structures similar to that of the platinum species studied and cobalt chloride were additionally tested for comparison. The hexachloroplatinate and tetrachloroplatinate salts showed exceptionally high reactivity with the cysteine peptide (EC₁₅ values of 1.4 and 14 μM, respectively). However, for platinum compounds (e.g. hydrogen hexahydroxyplatinate and tetraammineplatinum) where clinical and epidemiological evidence indicates limited sensitization potential, the cysteine DPRA showed only minor or no reactivity (EC₁₅ values of 24 600 and >30 000 μM, respectively). The outcomes of the lysine peptide assays were less robust and where EC₁₅ was measurable, values were substantially higher than the corresponding results from the cysteine assay. This work supports the value of in chemico peptide reactivity as a metric for assessment of platinum sensitization potential and therefore in screening of new platinum compounds for low or absent sensitization potential. Additional studies are required to determine whether the DPRA may be successfully applied to other metals. We provide details on method modifications and precautions important to the success of the DPRA in the assessment of metal reactivity.

Syngeneic red blood cell-induced extracellular vesicles suppress delayed-type hypersensitivity to self-antigens in mice

BACKGROUND

At present, the role of autologous cells as antigen carriers inducing immune tolerance is appreciated. Accordingly, intravenous administration of haptenated syngeneic mouse red blood cells (sMRBC) leads to hapten-specific suppression of contact hypersensitivity (CHS) in mice, mediated by light chain-coated extracellular vesicles (EVs). Subsequent studies suggested that mice intravenously administered with sMRBC alone may also generate regulatory EVs, revealing the possible self-tolerogenic potential of autologous erythrocytes.

OBJECTIVES

The current study investigated the immune effects induced by mere intravenous administration of a high dose of sMRBC in mice.

METHODS

The self-tolerogenic potential of EVs was determined in a newly developed mouse model of delayed-type hypersensitivity (DTH) to sMRBC. The effects of EV's action on DTH effector cells were evaluated cytometrically. The suppressive activity of EVs, after coating with anti-hapten antibody light chains, was assessed in hapten-induced CHS in wild-type or miRNA-150^-/- mice.

RESULTS

Intravenous administration of sMRBC led to the generation of CD9 + CD81+ EVs that suppressed sMRBC-induced DTH in a miRNA-150-dependent manner. Furthermore, the treatment of DTH effector cells with sMRBC-induced EVs decreased the activation of T cells but enhanced their apoptosis. Finally, EVs coated with antibody light chains inhibited hapten-induced CHS.

CONCLUSIONS AND CLINICAL RELEVANCE

The current study describes a newly discovered mechanism of self-tolerance induced by the intravenous delivery of a high dose of sMRBC that is mediated by EVs in a miRNA-150-dependent manner. This mechanism implies the concept of naturally occurring immune tolerance, presumably activated by overloading of the organism with altered self-antigens.

The Associations between Immunological Reactivity to the Haptenation of Unconjugated Bisphenol A to Albumin and Protein Disulfide Isomerase with Alpha-Synuclein Antibodies

Patients with Parkinson’s disease (PD) have increased susceptibility to bisphenol A (BPA) exposure since they have an impaired biotransformation capacity to metabolize BPA. PD subjects have reduced levels of conjugated BPA compared to controls. Reduced ability to conjugate BPA provides increased opportunity for unconjugated BPA to bind to albumin in human serum and protein disulfide isomerase on neurons. Once unconjugated BPA binds to proteins, it changes the allosteric structure of the newly configured protein leading to protein misfolding and the ability of the newly configured protein to act as a neoantigen. Once this neoantigen is formed, the immune system produces antibodies against it. The goal of our research was to investigate associations between unconjugated BPA bound to human serum albumin (BPA–HSA) antibodies and alpha-synuclein antibodies and between Protein Disulfide Isomerase (PDI) antibodies and alpha-synuclein antibodies. Enzyme–linked immunosorbent assay was used to determine the occurrences of alpha-synuclein antibodies, antibodies to BPA–HSA adducts, and PDI antibodies in the sera of blood donors. Subjects that exhibited high levels of unconjugated BPA–HSA antibodies or PDI antibodies had correlations and substantial risk for also exhibiting high levels of alpha-synuclein antibodies (p < 0.0001). We conclude that there are significant associations and risks between antibodies to BPA–HSA adducts and PDI antibodies for developing alpha-synuclein antibodies.

Novel cutaneous mediators of chemical allergy

Chemical allergy can manifest into allergic contact dermatitis and asthma and the importance of skin sensitization in both of these diseases is increasingly being recognized. Given the unique characteristics of chemical allergy, coupled with the distinct immunological microenvironment of the skin research is still unraveling the mechanisms through which sensitization and elicitation occur. This review first describes the features of chemical sensitization and the known steps that must occur to develop a chemical allergy. Next, the unique immunological properties of the skin - which may influence chemical sensitization - are highlighted. Additionally, mediators involved with the development of allergy are reviewed, starting with early ones - including the properties of haptens, skin integrity, the microbiome, the inflammasome, and toll-like receptors (TLR). Novel cellular mediators of chemical sensitization are highlighted, including innate lymphoid cells, mast cells, T-helper (T_H) cell subsets, and skin intrinsic populations including γδ T-cells and resident memory T-cells. Finally, this review discusses two epigenetic mechanisms that can influence chemical sensitization, microRNAs and DNA methylation. Overall, this review highlights recent research investigating novel mediators of chemical allergy that are present in the skin. It also emphasizes the need to further explore these mediators to gain a better understanding of what makes a chemical an allergen, and how best to prevent the development of chemical-induced allergic diseases.

One science-driven approach for the regulatory implementation of alternative methods: A multi-sector perspective

EU regulations call for the use of alternative methods to animal testing. During the last decade, an increasing number of alternative approaches have been formally adopted. In parallel, new 3Rs-relevant technologies and mechanistic approaches have increasingly contributed to hazard identification and risk assessment evolution. In this changing landscape, an EPAA meeting reviewed the challenges that different industry sectors face in the implementation of alternative methods following a science-driven approach. Although clear progress was acknowledged in animal testing reduction and refinement thanks to an integration of scientifically robust approaches, the following challenges were identified: i) further characterization of toxicity pathways; ii) development of assays covering current scientific gaps, iii) better characterization of links between in vitro readouts and outcome in the target species; iv) better definition of alternative method applicability domains, and v) appropriate implementation of the available approaches. For areas having regulatory adopted alternative methods (e.g., vaccine batch testing), harmonised acceptance across geographical regions was considered critical for broader application. Overall, the main constraints to the application of non-animal alternatives are the still existing gaps in scientific knowledge and technological limitations. The science-driven identification of most appropriate methods is key for furthering a multi-sectorial decrease in animal testing.

Risks of Allergic Contact Dermatitis Elicited by Nickel, Chromium, and Organic Sensitizers: Quantitative Models Based on Clinical Patch Test Data

Risks of allergic contact dermatitis (ACD) from consumer products intended for extended (nonpiercing) dermal contact are regulated by E.U. Directive EN 1811 that limits released Ni to a weekly equivalent dermal load of ≤0.5 μg/cm² . Similar approaches for thousands of known organic sensitizers are hampered by inability to quantify respective ACD-elicitation risk levels. To help address this gap, normalized values of cumulative risk for eliciting a positive ("≥+") clinical patch test response reported in 12 studies for a total of n = 625 Ni-sensitized patients were modeled in relation to observed ACD-eliciting Ni loads, yielding an approximate lognormal (LN) distribution with a geometric mean and standard deviation of GM_Ni = 15 μg/cm² and GSD_Ni = 8.0, respectively. Such data for five sensitizers (including formaldehyde and 2-hydroxyethyl methacrylate) were also ∼LN distributed, but with a common GSD value equal to GSD_Ni and with heterogeneous sensitizer-specific GM values each defining a respective ACD-eliciting potency GM_Ni /GM relative to Ni. Such potencies were also estimated for nine (meth)acrylates by applying this general LN ACD-elicitation risk model to respective sets of fewer data. ACD-elicitation risk patterns observed for Cr(VI) (n = 417) and Cr(III) (n = 78) were fit to mixed-LN models in which ∼30% and ∼40% of the most sensitive responders, respectively, were estimated to exhibit a LN response also governed by GSD_Ni . The observed common LN-response shape parameter GSD_Ni may reflect a common underlying ACD mechanism and suggests a common interim approach to quantitative ACD-elicitation risk assessment based on available clinical data.

Biomimetic trapping cocktail to screen reactive metabolites: use of an amino acid and DNA motif mixture as light/heavy isotope pairs differing in mass shift

Candidate drugs that can be metabolically transformed into reactive electrophilic products, such as epoxides, quinones, and nitroso compounds, are of special concern because subsequent covalent binding to bio-macromolecules can cause adverse drug reactions, such as allergic reactions, hepatotoxicity, and genotoxicity. Several strategies have been reported for screening reactive metabolites, such as a covalent binding assay with radioisotope-labeled drugs and a trapping method followed by LC-MS/MS analyses. Of these, a trapping method using glutathione is the most common, especially at the early stage of drug development. However, the cysteine of glutathione is not the only nucleophilic site in vivo; lysine, histidine, arginine, and DNA bases are also nucleophilic. Indeed, the glutathione trapping method tends to overlook several types of reactive metabolites, such as aldehydes, acylglucuronides, and nitroso compounds. Here, we introduce an alternate way for screening reactive metabolites as follows: A mixture of the light and heavy isotopes of simplified amino acid motifs and a DNA motif is used as a biomimetic trapping cocktail. This mixture consists of [²H₀]/[²H₃]-1-methylguanidine (arginine motif, Δ 3 Da), [²H₀]/[²H₄]-2-mercaptoethanol (cysteine motif, Δ 4 Da), [²H₀]/[²H₅]-4-methylimidazole (histidine motif, Δ 5 Da), [²H₀]/[²H₉]-n-butylamine (lysine motif, Δ 9 Da), and [¹³C₀,¹⁵N₀]/[¹³C₁,¹⁵N₂]-2'-deoxyguanosine (DNA motif, Δ 3 Da). Mass tag triggered data-dependent acquisition is used to find the characteristic doublet peaks, followed by specific identification of the light isotope peak using MS/MS. Forty-two model drugs were examined using an in vitro microsome experiment to validate the strategy. Graphical abstract Biomimetic trapping cocktail to screen reactive metabolites.

Determination of Protein Haptenation by Chemical Sensitizers Within the Complexity of the Human Skin Proteome

Skin sensitization associated with the development of allergic contact dermatitis occurs via a number of specific key events at the cellular level. The molecular initiating event (MIE), the first in the sequence of these events, occurs after exposure of the skin to an electrophilic chemical, causing the irreversible haptenation of proteins within skin. Characterization of this MIE is a key step in elucidating the skin sensitization adverse outcome pathway and is essential to providing parameters for mathematical models to predict the capacity of a chemical to cause sensitization. As a first step to addressing this challenge, we have exposed complex protein lysates from a keratinocyte cell line and human skin tissue with a range of well characterized sensitizers, including dinitrochlorobenzene, 5-chloro-2-methylisothiazol-3-one, cinnamaldehyde, and the non (or weak) sensitizer 6-methyl coumarin. Using a novel stable isotope labeling approach combined with ion mobility-assisted data independent mass spectrometry (HDMSE), we have characterized the haptenome for these sensitizers. Although a significant proportion of highly abundant proteins were haptenated, we also observed the haptenation of low abundant proteins by all 3 of the chemical sensitizers tested, indicating that within a complex protein background, protein abundance is not the sole determinant driving haptenation, highlighting a relationship to tertiary protein structure and the amino acid specificity of these chemical sensitizers and sensitizer potency.

Nature and kinetics of redox imbalance triggered by respiratory and skin chemical sensitizers on the human monocytic cell line THP-1

Low molecular weight reactive chemicals causing skin and respiratory allergies are known to activate dendritic cells (DC), an event considered to be a key step in both pathologies. Although generation of reactive oxygen species (ROS) is considered a major danger signal responsible for DC maturation, the mechanisms leading to cellular redox imbalance remain poorly understood. Therefore, the aim of this study was to unveil the origin and kinetics of redox imbalance elicited by 1-fluoro-2,4-dinitrobenzene (DNFB) and trimellitic anhydride chloride (TMAC), two golden standards of skin and chemical respiratory allergy, respectively. To track this goal, we addressed the time course modifications of ROS production and cellular antioxidant defenses as well as the modulation of MAPKs signaling pathways and transcription of pathophysiological relevant genes in THP-1 cells. Our data shows that the thiol-reactive sensitizer DNFB directly reacts with cytoplasmic glutathione (GSH) causing its rapid and marked depletion which results in a general increase in ROS accumulation. In turn, TMAC, which preferentially reacts with amine groups, induces a delayed GSH depletion as a consequence of increased mitochondrial ROS production. These divergences in ROS production seem to be correlated with the different extension of intracellular signaling pathways activation and, by consequence, with distinct transcription kinetics of genes such as HMOX1, IL8, IL1B and CD86. Ultimately, our observations may help explain the distinct DC phenotype and T-cell polarizing profile triggered by skin and respiratory sensitizers.

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Distinctive ROS origin and kinetics elicited by skin and respiratory sensitizers.

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ROS production elicited by DNFB results primarily from direct GSH haptenation.

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Distinct expression of genes involved in DC maturation and T-cell polarizing capacity.

Conjugation of nitrated acetaminophen to Der p1 amplifies peripheral blood monocyte response to Der p1

BACKGROUND

An association of acetaminophen use and asthma was observed in the International Study of Asthma and Allergies in Childhood study. However there are no clear mechanisms to explain an association between acetaminophen use and immunologic pathology. In acidic conditions like those in the stomach and inflamed airway, tyrosine residues are nitrated by nitrous and peroxynitrous acids. The resulting nitrotyrosine is structurally similar to 2,4-dinitrophenol and 2,4-dinitrochlorobenzene, known haptens that enhance immune responses by covalently binding proteins. Nitrated acetaminophen shares similar molecular structure.

OBJECTIVE

We hypothesized the acetaminophen phenol ring undergoes nitration under acidic conditions, producing 3-nitro-acetaminophen which augments allergic responses by acting as a hapten for environmental allergens.

METHODS

3-nitro-acetaminophen was formed from acetaminophen in the presence of acidified nitrite, purified by high performance liquid chromatography, and assayed by gas-chromatography mass spectrometry. Purified 3-nitro-acetaminophen was reacted with Dermatophagoides pteronyssinus (Der p1) and analyzed by mass spectrometry to identify the modification site. Human peripheral blood mononuclear cells proliferation response was measured in response to 3-nitro-acetaminophen and to 3-nitro-acetaminophen-modified Der p1.

RESULTS

Acetaminophen was modified by nitrous acid forming 3-nitro-acetaminophen over a range of different acidic conditions consistent with airway inflammation and stomach acidity. The Der p1 protein-hapten adduct creation was confirmed by liquid chromatography-mass spectrometry proteomics modifying cysteine 132. Peripheral blood mononuclear cells exposed to 3-nitro-acetaminophen-modified Der p1 had increased proliferation and cytokine production compared to acetaminophen and Der p1 alone (n = 7; p < 0.05).

CONCLUSION

These data suggests 3-nitro-acetaminophen formation and reaction with Der p1 provides a mechanism by which stomach acid or infection-induced low airway pH in patients could enhance the allergic response to proteins such as Der p1.

3-(Bromomethyl)-2-chloro-4-(methylsulfonyl)- benzoic acid: a new cause of sensitiser induced occupational asthma, rhinitis and urticaria

OBJECTIVES

3-(Bromomethyl)-2-chloro-4-(methylsulfonyl)-benzoic acid (BCMBA) has not previously been identified as a respiratory sensitiser. We detected two cases who presented respiratory and urticaria symptoms related to BCMBA and had positive skin prick tests to the agent. Subsequently, we conducted outbreak investigations at the BCMBA-producing factory and performed clinical examinations to confirm occupational diseases.

METHODS

The outbreak investigations included observations of work processes, assessment of exposure, a medical survey with a questionnaire and skin prick tests with 0.5% BCMBA water solution on 85 exposed workers and 9 unexposed workers. We used specific inhalation or nasal challenge and open skin application test to investigate BCMBA-related occupational asthma, rhinitis and contact urticaria.

RESULTS

We identified nine workers with respiratory and/or skin symptoms and positive skin prick tests to BCMBA in a chemical factory. A survey among chemical factory workers indicated a BCMBA-related sensitisation rate of 8% among all exposed workers; the rate was highest (25%) among production workers in the production hall. Sensitisation was detected only in workers with the estimated highest exposure levels. Six cases of occupational asthma, rhinitis and/or contact urticaria caused by BCMBA were confirmed with challenge tests. Asthma-provoking doses in specific inhalation challenges were very low (0.03% or 0.3% BCMBA in lactose).

CONCLUSIONS

We identified a new low molecular weight agent causing occupational asthma, rhinitis and contact urticaria. A typical clinical picture of allergic diseases and positive skin prick tests suggest underlying IgE-mediated disease mechanisms. Stringent exposure control measures are needed in order to prevent BCMBA-related diseases.

A New Pathway for Protein Haptenation by β-Lactams

The covalent binding of β-lactams to proteins upon photochemical activation has been demonstrated by using an integrated approach that combines photochemical, proteomic and computational studies, selecting human serum albumin (HSA) as a target protein and ezetimibe (1) as a probe. The results have revealed a novel protein haptenation pathway for this family of drugs that is an alternative to the known nucleophilic ring opening of β-lactams by the free amino group of lysine residues. Thus, photochemical ring splitting of the β-lactam ring, following a formal retro-Staudinger reaction, gives a highly reactive ketene intermediate that is trapped by the neighbouring lysine residues, leading to an amide adduct. For the investigated 1/HSA system, covalent modification of residues Lys414 and Lys525, which are located in sub-domains IIIA and IIIB, respectively, occurs. The observed photobinding may constitute the key step in the sequence of events leading to photoallergy. Docking and molecular dynamics simulation studies provide an insight into the molecular basis of the selectivity of 1 for these HSA sub-domains and the covalent modification mechanism. Computational studies also reveal positive cooperative binding of sub-domain IIIB that explains the experimentally observed modification of Lys414, which is located in a barely accessible pocket (sub-domain IIIA).