Modulatory Effects of Pb2+ on Virally Challenged Chicken Macrophage (HD-11) and B-Lymphocyte (DT40) Cell Lines In Vitro

A novel trivalent inactivated Salmonella vaccine formulated with CpG ODNs to enhance the cellular immunity in chickens

This study aimed to develop and evaluate a CpG oligodeoxynucleotide (CpG ODN)-adjuvanted trivalent inactivated Salmonella vaccine including S. enterica subsp. Enterica serovar Typhimurium, Salmonella enterica subsp. Enterica serovar Enteritidis, and Salmonella enterica serotype Infantis, for its immunogenic efficacy in chickens. The immunomodulatory effects of various CpG ODNs were assessed based on proinflammatory cytokine secretion and the expression levels of CD80, CD86, and MHC-II in the chicken cell lines HD11 and DT40. According to the results, CpG ODNs D35 3CG PO, D35 3CG MB, 1466 Acore PO, 1466 Acore MB, and K3 which exhibited non-cytotoxicity in both HD11 and DT40 cell lines, were selected for vaccine formulation. To evaluate their effects under in vivo conditions, chicks (n = 25) were randomly assigned to fourteen groups (G1: only sterile pyrogen-free saline solution, G2: only inactivated vaccine, G3: inactivated vaccine with 150 mg/dose of ALUM, G4: commercial Salenvac T vaccine, G5-G14: various experimental vaccine formulations which included different CpG ODNs combined with inactivated bacterial strains, with or without ALUM). Immune responses were analyzed through serological assays for antigen-specific antibody titers and ex vivo splenocyte cultures for cytokine secretion. Flow cytometry was performed to assess T-cell activation and IFN-γ production. The results demonstrated that the CpG ODNs-adjuvanted vaccine formulations significantly enhanced both humoral and cellular immunity compared to the commercial vaccine. Specifically, the Vac#5+ ALUM formulation, which included the K3 CpG ODN, induced robust antibody responses against Salmonella antigens and significantly increased IFN-γ secretion, nearly two-fold higher than the commercial vaccine. This effect was primarily mediated by CD4+ helper and CD8+ cytotoxic T cells. These findings highlight the potential of CpG ODNs as effective vaccine adjuvants in poultry. To the best of our knowledge, this is the first study to investigate the use of CpG ODNs as adjuvants in inactivated Salmonella vaccine formulations. Future studies should focus on evaluating the long-term protective efficacy of this vaccine formulation and its ability to provide cross-protection against a broader spectrum of Salmonella serovars.

Modulatory effects of inorganic mercury (Hg (II)) and lead (Pb (II)) on immune responses of Pekin ducklings (Anas platyrhynchos domesticus) upon a viral-like immune challenge

Trace metal contamination is ubiquitous around the world and may affect the health of wildlife. Divalent trace metals, including ions of mercury (Hg) and lead (Pb), have been shown to be immunotoxic to avian species. However, little is known about the immunomodulatory effects of trace metal exposure on viral infections, especially in young birds, who may be more sensitive. Therefore, the objective of the current study is to provide more insights in the causality between trace metal exposure and the effects of exposure on the immune responses in young waterfowls. Pekin duckling was used as an animal model to investigate the effects of inorganic divalent Hg (II) and Pb (II) on avian immune responses upon a viral-like challenge with double-stranded RNA. Our results indicate that Hg (II) altered the immune gene expression 24 h post-challenge, as reflected by induction of pro-inflammatory genes IL-8, iNOS, TLR3 and TLR7, and a significant decrease of microRNA-155. Ducklings exposed to Pb (II) showed lower levels of natural antibodies, reduced white blood cell counts and lower heterophil proportions 24 h post-challenge. Although inorganic divalent Hg (II) and Pb (II) showed specific differential effects on the immune response of Pekin ducklings, the overall adverse immunomodulatory outcomes in both cases point to inflammation, impaired B-cell function, and weaker immunocompetence.

Higher blood manganese level associated with increased risk of adult latent tuberculosis infection in the US population

Background

The associations between blood heavy metal levels and latent tuberculosis infection (LTBI) have not been fully elucidated. The aim of this study was to investigate the potential association between blood heavy metal levels and LTBI in adults using National Health and Nutrition Examination Survey data from 2011 to 2012.

Methods

We enrolled 1710 participants in this study, and compared the baseline characteristics of participants involved. Multivariate logistic regression analysis, restricted cubic splines (RCS) analysis, along with subgroup analysis and interaction tests were utilized to explore the association between blood manganese (Mn) level and LTBI risk.

Results

Participants with LTBI had higher blood Mn level compared to non-LTBI individuals (p < 0.05), while the levels of lead, cadmium, total mercury, selenium, copper, and zinc did not differ significantly between the two groups (p > 0.05). In the fully adjusted model, a slight increase in LTBI risk was observed with each 1-unit increase in blood Mn level (OR = 1.00, 95% CI: 1.00-1.01, p = 0.02). Participants in the highest quartile of blood Mn level had a threefold increase in LTBI risk compared to those in the lowest quartile (OR = 4.01, 95% CI: 1.22-11.33, p = 0.02). RCS analysis did not show a non-linear relationship between blood Mn level and LTBI (non-linear p-value = 0.0826). Subgroup analyses and interaction tests indicated that age, alcohol consumption, and income-to-poverty ratio significantly influenced LTBI risk (interaction p-values<0.05).

Conclusion

Individuals with LTBI had higher blood Mn level compared to non-LTBI individuals, and higher blood Mn level associated with increased LTBI risk.

Increased cytotoxicity of Pb2+ with co-exposures to a mitochondrial uncoupler and mitochondrial calcium uniporter inhibitor

Lead (Pb2+) is an important developmental toxicant. The mitochondrial calcium uniporter (MCU) imports calcium ions using the mitochondrial membrane potential (MMP), and also appears to mediate the influx of Pb2+ into the mitochondria. Since our environment contains mixtures of toxic agents, it is important to consider multi-chemical exposures. To begin to develop generalizable, predictive models of interactive toxicity, we developed mechanism-based hypotheses about interactive effects of Pb2+ with other chemicals. To test these hypotheses, we exposed HepG2 (human liver) cells to Pb2+ alone and in mixtures with other mitochondria-damaging chemicals: carbonyl cyanide-p-trifluoromethoxyphenylhydrazone (FCCP), a mitochondrial uncoupler that reduces MMP, and Ruthenium Red (RuRed), a dye that inhibits the MCU. After 24 hours, Pb2+ alone, the mixture of Pb2+ and RuRed, and the mixture of Pb2+ and FCCP caused no decrease in cell viability. However, the combination of all three exposures led to a significant decrease in cell viability at higher Pb2+ concentrations. After 48 hours, the co-exposure to elevated Pb2+ concentrations and FCCP caused a significant decrease in cell viability, and the mixture of all three showed a clear dose-response curve with significant decreases in cell viability across a range of Pb2+ concentrations. We performed ICP-MS analyses on isolated mitochondrial and cytosolic fractions and found no differences in Pb2+ uptake across exposure groups, ruling out altered cellular uptake as the mechanism for interactive toxicity. We assessed MMP following exposure and observed a decrease in membrane potential that corresponds to loss of cell viability but is likely not sufficient to be the causative mechanistic driver of cell death. This research provides a mechanistically-based framework for understanding Pb2+ toxicity in mixtures with mitochondrial toxicants.

Evaluation of the Effect of Pb Pollution on Avian Influenza Virus-Specific Antibody Production in Black-Headed Gulls (Chroicocephalus ridibundus)

Lead (Pb), an environmental pollutant, has been widely reported to have contaminated mammals, including humans and birds. This study focuses on the effects of Pb pollution on avian influenza virus (AIV) antibody production. A total of 170 black-headed gulls (Chroicocephalus ridibundus) were captured in Tokyo Bay (TBP) from January 2019 to April 2020 and in Mikawa Bay (MBP) from November 2019 to April 2021. The gulls were weighed, subjected to blood sampling, and released with a ring band on their tarsus. The samples were used to measure blood Pb levels (BLL) and AIV-specific antibodies. The BLL were compared using the Wilcoxon two-sample test between the period when black-headed gulls arrived and the wintering period, defined by the number of gulls counted in each area. A significant increase was found in the TBP. A decrease in BLL significantly increased antibody titer during wintering in TBP and MBP. Pb pollution had a negative effect on the production of AIV antibodies. These findings suggest that wild birds that were contaminated by Pb in the environment may facilitate the spread of zoonotic diseases, further increasing the possibility that environmental pollutants may threaten human health.

Modulatory Effects of Mercury (II) Chloride (HgCl2 ) on Chicken Macrophage and B-Lymphocyte Cell Lines with Viral-Like Challenges In Vitro

Mercury (Hg) is a toxic trace metal ubiquitously distributed in the environment. Inorganic mercury (as HgCl₂ ) can cause immunotoxicity in birds, but the mechanisms of action are still not fully resolved, especially with respect to responses to viral infections. To investigate the potential immunomodulatory effects of Hg²⁺ on specific cell types of the avian immune system, chicken macrophage (HD-11) and B-lymphocyte (DT40) cell lines were applied as in vitro models for the innate and adaptive immune systems, respectively. The cells were stimulated with synthetic double-stranded RNA, which can be recognized by toll-like receptor-3 to mimic a viral infection. The Hg²⁺ showed concentration-dependent cytotoxicity in both cell lines, with similar median effect concentrations at 30 µM. The cytotoxicity of Hg²⁺ was closely related to glutathione (GSH) depletion and reactive oxygen species induction, whereas the de novo synthesis of GSH acted as a primary protective strategy. Nitric oxide produced by activated macrophages was strongly inhibited by Hg²⁺ , and was also influenced by cellular GSH levels. Cell proliferation, gene expression of microRNA-155, and cellular IgM levels in B cells were decreased at noncytotoxic Hg²⁺ concentrations. The secretion of antiviral interferon-α was induced by Hg²⁺ in both cell lines. Overall, our results suggest that Hg²⁺ exposure can cause immunomodulatory effects in birds by disrupting immune cell proliferation and cytokine production, and might result in disorders of the avian immune system. Environ Toxicol Chem 2021;40:2813-2824. © 2021 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Toxic metal exposure as a possible risk factor for COVID-19 and other respiratory infectious diseases

Multiple medical, lifestyle, and environmental conditions, including smoking and particulate pollution, have been considered as risk factors for COronaVIrus Disease 2019 (COVID-19) susceptibility and severity. Taking into account the high level of toxic metals in both particulate matter (PM2.5) and tobacco smoke, the objective of this review is to discuss recent data on the role of heavy metal exposure in development of respiratory dysfunction, immunotoxicity, and severity of viral diseases in epidemiological and experimental studies, as to demonstrate the potential crossroads between heavy metal exposure and COVID-19 severity risk. The existing data demonstrate that As, Cd, Hg, and Pb exposure is associated with respiratory dysfunction and respiratory diseases (COPD, bronchitis). These observations corroborate laboratory findings on the role of heavy metal exposure in impaired mucociliary clearance, reduced barrier function, airway inflammation, oxidative stress, and apoptosis. The association between heavy metal exposure and severity of viral diseases, including influenza and respiratory syncytial virus has been also demonstrated. The latter may be considered a consequence of adverse effects of metal exposure on adaptive immunity. Therefore, reduction of toxic metal exposure may be considered as a potential tool for reducing susceptibility and severity of viral diseases affecting the respiratory system, including COVID-19.