Environmental Mold and Mycotoxin Exposures Elicit Specific Cytokine and Chemokine Responses

Background: Molds can cause respiratory symptoms and asthma. We sought to use isolated peripheral blood mononuclear cells (PBMCs) to understand changes in cytokine and chemokine levels in response to mold and mycotoxin exposures and to link these levels with respiratory symptoms in humans. We did this by utilizing an ex vivo assay approach to differentiate mold-exposed patients and unexposed controls. While circulating plasma chemokine and cytokine levels from these two groups might be similar, we hypothesized that by challenging their isolated white blood cells with mold or mold extracts, we would see a differential chemokine and cytokine release. Methods and Findings: Peripheral blood mononuclear cells (PBMCs) were isolated from blood from 33 patients with a history of mold exposures and from 17 controls. Cultured PBMCs were incubated with the most prominent Stachybotrys chartarum mycotoxin, satratoxin G, or with aqueous mold extract, ionomycin, or media, each with or without PMA. Additional PBMCs were exposed to spores of Aspergillus niger, Cladosporium herbarum and Penicillium chrysogenum. After 18 hours, cytokines and chemokines released into the culture medium were measured by multiplex assay. Clinical histories, physical examinations and pulmonary function tests were also conducted. After ex vivo PBMC exposures to molds or mycotoxins, the chemokine and cytokine profiles from patients with a history of mold exposure were significantly different from those of unexposed controls. In contrast, biomarker profiles from cells exposed to media alone showed no difference between the patients and controls. Conclusions: These findings demonstrate that chronic mold exposures induced changes in inflammatory and immune system responses to specific mold and mycotoxin challenges. These responses can differentiate mold-exposed patients from unexposed controls. This strategy may be a powerful approach to document immune system responsiveness to molds and other inflammation-inducing environmental agents

Iron-Responsive Olfactory Uptake of Manganese Improves Motor Function Deficits Associated with Iron Deficiency

Iron-responsive manganese uptake is increased in iron-deficient rats, suggesting that toxicity related to manganese exposure could be modified by iron status. To explore possible interactions, the distribution of intranasally-instilled manganese in control and iron-deficient rat brain was characterized by quantitative image analysis using T1-weighted magnetic resonance imaging (MRI). Manganese accumulation in the brain of iron-deficient rats was doubled after intranasal administration of MnCl2 for 1- or 3-week. Enhanced manganese level was observed in specific brain regions of iron-deficient rats, including the striatum, hippocampus, and prefrontal cortex. Iron-deficient rats spent reduced time on a standard accelerating rotarod bar before falling and with lower peak speed compared to controls; unexpectedly, these measures of motor function significantly improved in iron-deficient rats intranasally-instilled with MnCl2. Although tissue dopamine concentrations were similar in the striatum, dopamine transporter (DAT) and dopamine receptor D1 (D1R) levels were reduced and dopamine receptor D2 (D2R) levels were increased in manganese-instilled rats, suggesting that manganese-induced changes in post-synaptic dopaminergic signaling contribute to the compensatory effect. Enhanced olfactory manganese uptake during iron deficiency appears to be a programmed “rescue response” with beneficial influence on motor impairment due to low iron status

Transport and biological impact of manganese

Manganese (Mn) is an essential nutrient and, unlike other trace elements (e.g., iron), toxicity is more prevalent than dietary deficiency. This chapter will commence with a discussion on the essentiality of Mn and its general biological functions. We will then discuss putative Mn transport mechanisms with a particular emphasis on the lung and brain, the primary organs involved in the etiology of Mn neurotoxicity (manganism). We conclude the chapter with several sections focusing on the neurobiology of manganism. Special emphasis is placed on the neurochemical and biochemical aspects of Mn-induced neuropathology and the biochemical similarities it shares with Parkinson’s disease (PD)

Ingestion of Mn and Pb by rats during and after pregnancy alters iron metabolism and behavior in offspring

Manganese (Mn) and lead (Pb) exposures during developmental period can impair development by direct neurotoxicity or through interaction with iron metabolism. Therefore, we examined the effects of maternal ingestion of Mn or Pb in drinking water during gestation and lactation on iron metabolism as well as behavior in their offspring. Pregnant dams were given distilled water, 4.79mg/ml Mn, or 2.84mg/ml Pb in drinking water during gestation and lactation. Pups were studied at time of weaning for (59)Fe absorption from the gut, duodenal divalent metal transporter 1 (DMT1) expression, hematological parameters, and anxiety-related behavior using an Elevated Plus Maze (EPM) test. Metal-exposed pups had lower body weights and elevated blood and brain concentrations of the respective metal. Pb-exposed pups had lower hematocrits and higher blood Zn protoporphyrin levels. In contrast, Mn exposed pups had normal hematological parameters but significantly reduced Zn protoporphyrin. Pharmacokinetic studies using (59)Fe showed that intestinal absorption in metal-exposed pups was not different from controls, nor was it correlated with duodenal DMT1 expression. However, intravenously injected (59)Fe was cleared more slowly in Pb-exposed pups resulting in higher plasma levels. The overall tissue uptake of (59)Fe was lower in Mn-exposed and lower in the brain in Pb-exposed pups. The EPM test demonstrated that Mn-exposed, but not Pb-exposed, pups had lower anxiety-related behavior compared to controls. We conclude that gestational and lactational exposures to Mn or Pb differentially alter Fe metabolism and anxiety-related behavior. The data suggest that perturbation in Fe metabolism may contribute to the pathophysiologic consequences of Mn and Pb exposure during early development

Effect of iron deficiency and manganese instillation on the expression of dopamine transporters and receptors in the striatum.

<p>Rats intranasally instilled with MnCl₂ (6×10 mg/kg) were euthanized and striatal tissues were collected and homogenized to determine the expression levels of dopamine transporter (DAT; <b>A</b>), dopamine receptor D₁ (D1R; <b>B</b>), and dopamine receptor D₂ (D2R; <b>C</b>). Relative intensities of protein bands normalized to actin were determined using Odyssey software (version 2.1). Empty and closed bars represent water-instilled and MnCl₂-instilled rats, respectively. Data were presented as mean ± SEM (N = 3–4 per group) and were analyzed using two-way ANOVA.</p

Effects of iron deficiency on manganese accumulation in the brain after intranasal instillation.

<p>After intranasal instillation of MnCl₂ (3×10 mg/kg for 1 wk or 6×10 mg/kg for 3 wks), a signal intensity ratio of brain to the background for each image was calculated and corrected for endogenous signal intensity of respective diet group and then normalized to brain weight and dose. Manganese distribution in the axial sections of the brain tissue (<b>A</b>), in specific brain regions (<b>B</b>) and in the whole brain integrating all sections (<b>C</b>) was compared between control and iron-deficient rats. Empty and closed bars represent water-instilled and MnCl₂-instilled rats, respectively. Data were presented as mean ± SEM (N = 4–5). * <i>P</i><0.05 between control and iron-deficient rats determined by two-sample <i>t</i>-test. OB, olfactory bulb; OTR, olfactory tract; OTB, olfactory tubercle; PFC, prefrontal cortex; CPU, caudate-putamen or striatum; GP, globus pallidus; CTX, cortex; HPC, hippocampus.</p

Physiological and hematological characteristics of rats treated with olfactory manganese under iron deficiency.

<p>Data are presented as the mean ± SEM and were analyzed by two-way ANOVA; ND, not determined;</p>‡<p><i>P</i><0.05, effect of iron deficiency;</p>§<p><i>P</i><0.05, effect of interaction between MnCl₂ and iron deficiency.</p

Effect of iron deficiency and manganese exposure on motor coordination of the rat.

<p>Rats were pair-fed, intranasally instilled (6×10 mg/kg) for 3 wks, and tested on the rotarod device to record the time to falling-off (<b>A</b>) and speed of the rod (<b>B</b>). Empty and closed bars represent water-instilled and MnCl₂-instilled rats, respectively. Data were presented as mean ± SEM (N = 3–4 per group) and were analyzed using two-way ANOVA.</p