T Cell Activation in South African HIV-Exposed Infants Correlates with Ochratoxin A Exposure

HLA gene variations and mycotoxin toxicity: Four case reports

Mycotoxins are produced by certain molds that can cause many health effects. We present four human cases of prolonged consistent mycotoxins exposure linked to genetic variations in human leukocyte antigen (HLA) alleles. The HLA-DR/DQ isotype alleles are linked to mycotoxins susceptibility due to the lack of proper immune response; individuals with these alleles are poor eliminators of mycotoxins from their system. Four subjects with variations in their HLA-DR alleles were exposed to mycotoxins from living in mold-infested houses and experienced persistent mold-related symptoms long after moving out from the mold-infested houses and only exposed to the levels of molds found in the ambient air. From one of the subjects, two urine samples were collected ~ 18 months apart after the cessation of exposure. Urinary elimination rate was extremely slow for two of the mycotoxins (ochratoxin A [OTA] and mycophenolic acid [MPA]) detected in both samples. In 18 months, decline in OTA level was only ~ 3-fold (estimated t½ of ~ 311 days) and decline in MPA level was ~ 11-fold (estimated t½ of ~ 160 days), which was ~ 10- and ~ 213-fold slower than expected in individuals without HLA-DR alleles, respectively. We estimated that ~ 4.3 and ~ 2.2 years will be required for OTA and MPA to reach < LLQ in urine, respectively. Three other subjects with variations in HLA-DR alleles were members of a family who lived in a mold-infested house for 4 years. They kept experiencing mold-related issues >2 years after moving to a non-mold-infested house. Consistent exposure was confirmed by the presence of several mycotoxins in urine >2 years after the secession of higher than background (from outdoor ambient air) exposure. This was consistent with the extremely slow elimination of mycotoxins from their system. Variations in HLA-DR alleles can, consequently, make even short periods of exposure to chronic exposure scenarios with related adverse health effects. It is, therefore, important to determine genetic predisposition as a reason for prolonged/lingering mold-related symptoms long after the cessation of higher than background exposure. Increased human exposure to mycotoxins is expected from increased mold infestation that is anticipated due to rising CO2, temperature, and humidity from the climate change with possibly increased adverse health effects, especially in individuals with genetic susceptibility to mold toxicity.

PCV2 infection aggravates OTA-induced immunotoxicity in vivo and in vitro

Ochratoxin A (OTA), frequently existing in the food and feeds, could induce immunotoxicity. Porcine circovirus type 2 (PCV2), as a primary causative agent of porcine circovirus-associated disease, also could induce immunosuppression. However, it is still unknown whether PCV2 infection impacts OTA-induced immunotoxicity. The pigs and porcine alveolar macrophages (PAMs) were used as the model in the present experiment. The results in vivo indicated that PCV2 infection exacerbated OTA-induced immunotoxicity, NF-κB p65 phosphorylation, and TLR4 and MyD88 mRNA and protein expression in spleen. The results in vitro showed that OTA at 7.0 and 9.0 μM decreased cell viability and increased LDH release of PAMs without PCV2 infection. However, with PCV2 infection, OTA at 5.0, 7.0 and 9.0 μM significantly decreased cell viability and increased LDH release compared with absence of PCV2 infection. In addition, OTA at 5.0 and 7.0 μM significantly increased Annexin V/PI-positive rate, apoptosis of nuclear, γ-H2AX foci, IL-1α and TNF-α expression in PAMs with PCV2 infection compared with absence of PCV2 infection. In addition, PCV2 infection enhanced OTA-induced TLR4 and MyD88 mRNA and protein expression and NF-κB p65 phosphorylation. Knockdown of TLR4 alleviated the exacerbating effects of PCV2 infection on OTA-induced cytotoxicity, apoptosis and DNA damage in PAMs. These results indicated that PCV2 infection aggravated OTA-induced immunotoxicity and reduced the dose of OTA-induced immunotoxicity via TLR4/NF-κB p65 signaling pathway, which could provide basis for establishing limits for OTA.

Ex Vivo and In Vitro Studies Revealed Underlying Mechanisms of Immature Intestinal Inflammatory Responses Caused by Aflatoxin M1 Together with Ochratoxin A

Aflatoxin M1 (AFM1) and ochratoxin A (OTA), which are occasionally detected in milk and commercial baby foods, could easily enter and reach the gastrointestinal tract, posing impairment to the first line of defense and causing dysfunction of the tissue. The objective of this study was to investigate the immunostimulatory roles of individual and combined AFM1 and OTA on the immature intestine. Thus, we used ELISA assays to evaluate the generation of cytokines from ex vivo CD-1 fetal mouse jejunum induced by AFM1 and OTA and explored the related regulatory pathways and pivot genes using RNA-seq analysis. It was found that OTA exhibited much stronger ability in stimulating pro-inflammatory cytokine IL-6 from jejunum tissues than AFM1 (OTA of 4 μM versus AFM1 of 50 μM), whereas the combination of the two toxins seemed to exert antagonistic actions. In addition, transcriptomics also showed that most gene members in the enriched pathway ‘cytokine–cytokine receptor interaction’ were more highly expressed in OTA than the AFM1 group. By means of PPI network analysis, NFKB1 and RelB were regarded as hub genes in response to OTA but not AFM1. In the human FHs 74 Int cell line, both AFM1 and OTA enhanced the content of reactive oxygen species, and the oxidative response was more apparent in OTA-treated cells in comparison with AFM1. Furthermore, OTA and AFM1 + OTA raised the protein abundance of p50/RelB, and triggered the translocation of the dimer from cytosol to nucleus. Therefore, the experimental data ex vivo and in vitro showed that OTA-induced inflammation was thought to be bound up with the up-regulation and translocation of NF-κB, though AFM1 seemed to have no obvious impact. Since it was the first attempt to uncover the appearances and inner mechanisms regarding inflammation provoked by AFM1 and OTA on immature intestinal models, further efforts are needed to understand the detailed metabolic steps of the toxin in cells and to clarify their causal relationship with the signals proposed from current research.

Mold, Mycotoxins and a Dysregulated Immune System: A Combination of Concern?

Fungi represent one of the most diverse and abundant eukaryotes on earth. The interplay between mold exposure and the host immune system is still not fully elucidated. Literature research focusing on up-to-date publications is providing a heterogenous picture of evidence and opinions regarding the role of mold and mycotoxins in the development of immune diseases. While the induction of allergic immune responses by molds is generally acknowledged, other direct health effects like the toxic mold syndrome are controversially discussed. However, recent observations indicate a particular importance of mold/mycotoxin exposure in individuals with pre-existing dysregulation of the immune system, due to exacerbation of underlying pathophysiology including allergic and non-allergic chronic inflammatory diseases, autoimmune disorders, and even human immunodeficiency virus (HIV) disease progression. In this review, we focus on the impact of mycotoxins regarding their impact on disease progression in pre-existing immune dysregulation. This is complemented by experimental in vivo and in vitro findings to present cellular and molecular modes of action. Furthermore, we discuss hypothetical mechanisms of action, where evidence is missing since much remains to be discovered.

Mannan Oligosaccharide Could Attenuate Ochratoxin A-Induced Immunosuppression with Long-Time Exposure Instead of Immunostimulation with Short-Time Exposure

Our previous study showed that ochratoxin A (OTA), one of the most common mycotoxins in feed, could induce immunosuppression with long-time exposure but immunostimulation with short-time exposure. However, limited studies for the control of OTA-induced two-way immune toxicity were carried out. This study explored the effects of mannan oligosaccharide (MOS), a glucomannoprotein complex with immunoregulatory capability derived from the yeast cell wall, on OTA-induced immune toxicity and its underlying mechanisms. Surprisingly, the results showed that MOS significantly attenuated immunosuppression induced by long-time OTA treatment but did not provide protection against immunostimulation induced by short-time OTA treatment on porcine alveolar macrophages (PAMs), as demonstrated by the expressions of inflammatory cytokines and the capability of migration and phagocytosis. Further, MOS increased the OTA-inhibited autophagy level and the JNK phosphorylation level on PAMs with long-time OTA treatment. In addition, the inhibition of autophagy by 3-MA or the inhibition of JNK phosphorylation by SP600125 could partly block the protective effects of MOS on OTA-induced immunosuppression. Importantly, the inhibition of JNK phosphorylation down-regulated the MOS-promoted autophagy level. In conclusion, MOS could attenuate OTA-induced immunosuppression with short-time exposure on PAMs through activating JNK-mediated autophagy but had no significant effects on OTA-induced immunostimulation with short-time exposure. Our study provides new insights into the application of MOS as an immunoregulator against mycotoxin-induced immune toxicity.

Transient Immune Activation in BCG-Vaccinated Infant Rhesus Macaques Is Not Sufficient to Influence Oral Simian Immunodeficiency Virus Infection

BCG vaccination has been demonstrated to increase levels of activated CD4+ T cells, thus potentially influencing mother-to-child transmission of human immunodeficiency virus (HIV). To assess the risk of BCG vaccination in HIV infection, we randomly assigned newborn rhesus macaques to receive BCG vaccine or remain unvaccinated and then undergo oral simian immunodeficiency virus (SIV) challenges 3 weeks later. We observed elevated levels of activated peripheral CD4+ T cells (ie, HLA-DR+CD38+CCR5+ CD4+ T cells) by week 3 after vaccination. BCG was also associated with an altered immune gene expression profile, as well as with monocyte activation in both peripheral blood and the draining axillary lymph node, indicating significant BCG vaccine-induced immune activation. Despite these effects, BCG vaccination did not increase the rate of SIV oral transmission or disease progression. Our findings therefore identify patterns of T-cell and monocyte activation that occur after BCG vaccination but do not support the hypothesis that BCG vaccination is a risk factor for postnatal HIV transmission or increased pathogenesis in infants.

Mycotoxin Occurrence, Exposure and Health Implications in Infants and Young Children in Sub-Saharan Africa: A Review

Infants and young children (IYC) remain the most vulnerable population group to environmental hazards worldwide, especially in economically developing regions such as sub-Saharan Africa (SSA). As a result, several governmental and non-governmental institutions including health, environmental and food safety networks and researchers have been proactive toward protecting this group. Mycotoxins, toxic secondary fungal metabolites, contribute largely to the health risks of this young population. In SSA, the scenario is worsened by socioeconomic status, poor agricultural and storage practices, and low level of awareness, as well as the non-establishment and lack of enforcement of regulatory limits in the region. Studies have revealed mycotoxin occurrence in breast milk and other weaning foods. Of concern is the early exposure of infants to mycotoxins through transplacental transfer and breast milk as a consequence of maternal exposure, which may result in adverse health effects. The current paper presents an overview of mycotoxin occurrence in foods intended for IYC in SSA. It discusses the imperative evidence of mycotoxin exposure of this population group in SSA, taking into account consumption data and the occurrence of mycotoxins in food, as well as biomonitoring approaches. Additionally, it discusses the health implications associated with IYC exposure to mycotoxins in SSA.