Diesel exhaust (DE) aggravates pathology of delayed-type hypersensitivity (DTH) induced by methyl-bovine serum albumin (mBSA) in mice

A polysaccharide from Pleurotus citrinopileatus mycelia enhances the immune response in cyclophosphamide-induced immunosuppressed mice via p62/Keap1/Nrf2 signal transduction pathway

The manuscript aimed to study the immunoregulatory activity and the mechanism of the polysaccharide (CMP) from Pleurotus citrinopileatus mycelia. The mice were divided into normal group, model group, different dosage of CMP (50, 100 and 200 mg/kg, respectively) groups and levamisole hydrochloride treated group. The results showed that, compared with the model group, CMP could significantly improve the auricle swelling rate, half hemolysis value and phagocytic index in mice. The indices of immune organs were raised, and tissue damage of spleen was relieved. Splenic Th1 cells were decreased, while Th2 cells were increased, furthermore the proliferation of splenic lymphocytes and the cytotoxicity of NK cells were increased. The levels of interleukin-12 (IL-12), interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α) in spleen were decreased, while interleukin-4 (IL-4) and interleukin-10 (IL-10) were increased. In serum and spleen, the levels of catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) activities were increased, while the level of malondialdehyde (MDA) was decreased. And the levels of Immunoglobulin were also increased. Western blot showed that CMP had immunoregulatory activity by activating Nrf2, Keap1, p62, HO-1, and NQO1 in the p62/Keap1/Nrf2 signaling pathway. The study proved that CMP could be used as a biological Immune regulating agent.

The Ability of AhR Ligands to Attenuate Delayed Type Hypersensitivity Reaction Is Associated With Alterations in the Gut Microbiota

Aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that regulates T cell function. The aim of this study was to investigate the effects of AhR ligands, 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD), and 6-Formylindolo[3,2-b]carbazole (FICZ), on gut-associated microbiota and T cell responses during delayed-type hypersensitivity (DTH) reaction induced by methylated bovine serum albumin (mBSA) in a mouse model. Mice with DTH showed significant changes in gut microbiota including an increased abundance of Bacteroidetes and decreased Firmicutes at the phylum level. Also, there was a decrease in Clostridium cluster XIV and IV, which promote anti-inflammatory responses, and an increase in Prevotella copri that facilitates pro-inflammatory responses. Interestingly, treatment of mice with TCDD attenuated the DTH response, induced Tregs, suppressed Th17 cells in the mesenteric lymph nodes (MLNs), and reversed the gut microbiota composition toward normalcy. In contrast, FICZ exacerbated the DTH response, induced heightened Th17 cells, and failed to cause a major shift in gut microbiota. Furthermore, TCDD but not FICZ caused an increase in the levels of short-chain fatty acids (SCFA), n-butyric acid, and acetic acid. Administration of sodium butyrate into mice with DTH suppressed the response, increased Tregs, and reduced Th17 cells IL17. Butyrate also caused an increase in the abundance of Clostridium and a decrease in Prevotella. Lastly, TCDD, as well as butyrate but not FICZ, were able to inhibit proinflammatory Histone deacetylases (HDACs) class I and II. Together, our data suggest that AhR ligands, such as TCDD that suppress DTH response, may mediate this effect by reversing the gut dysbiosis induced during this inflammatory response, while FICZ may fail to suppress the DTH response because of its inability to overturn the dysbiosis.

Nrf2 Lowers the Risk of Lung Injury via Modulating the Airway Innate Immune Response Induced by Diesel Exhaust in Mice

In the present study, we investigated the role of Nrf2 in airway immune responses induced by diesel exhaust (DE) inhalation in mice. C57BL/6J Nrf2^+/+ and Nrf2^−/− mice were exposed to DE or clean air for 8 h/day and 6 days/week for 4 weeks. After DE exposure, the number of neutrophils and macrophage inflammatory protein (MIP)-2 level in bronchoalveolar lavage fluid (BALF) and interleukin (IL)-17 level in the lung tissue increased in Nrf2^−/− mice compared with Nrf2^+/+ mice; however, the lack of an increase in the level of tumor necrosis factor (TNF)-α in the lung tissue in Nrf2^+/+ mice and mild suppression of the level of TNF-α in Nrf2^−/− mice were observed; the level of granulocyte macrophage colony-stimulating factor (GM-CSF) in the lung tissue decreased in Nrf2^−/− mice than in Nrf2^+/+ mice; the number of DE particle-laden alveolar macrophages in BALF were larger in Nrf2^−/− mice than in Nrf2^+/+ mice. The results of electron microscope observations showed alveolar type II cell injury and degeneration of the lamellar body after DE exposure in Nrf2^−/− mice. Antioxidant enzyme NAD(P)H quinone dehydrogenase (NQO)1 mRNA expression level was higher in Nrf2^+/+ mice than in Nrf2^−/− mice after DE exposure. Our results suggested that Nrf2 reduces the risk of pulmonary disease via modulating the airway innate immune response caused by DE in mice.

A role for TNF-α in alveolar macrophage damage-associated molecular pattern release

Chronic beryllium disease (CBD) is a metal hypersensitivity/autoimmune disease in which damage-associated molecular patterns (DAMPs) promote a break in T cell tolerance and expansion of Be2+/self-peptide-reactive CD4+ T cells. In this study, we investigated the mechanism of cell death induced by beryllium particles in alveolar macrophages (AMs) and its impact on DAMP release. We found that phagocytosis of Be led to AM cell death independent of caspase, receptor-interacting protein kinases 1 and 3, or ROS activity. Before cell death, Be-exposed AMs secreted TNF-α that boosted intracellular stores of IL-1α followed by caspase-8-dependent fragmentation of DNA. IL-1α and nucleosomal DNA were subsequently released from AMs upon loss of plasma membrane integrity. In contrast, necrotic AMs released only unfragmented DNA and necroptotic AMs released only IL-1α. In mice exposed to Be, TNF-α promoted release of DAMPs and was required for the mobilization of immunogenic DCs, the expansion of Be-reactive CD4+ T cells, and pulmonary inflammation in a mouse model of CBD. Thus, early autocrine effects of particle-induced TNF-α on AMs led to a break in peripheral tolerance. This potentially novel mechanism may underlie the known relationship between fine particle inhalation, TNF-α, and loss of peripheral tolerance in T cell-mediated autoimmune disease and hypersensitivities.

Iron oxide nanoparticles attenuate T helper 17 cell responses in vitro and in vivo

Iron oxide nanoparticles (IONPs) have been shown to attenuate T helper (Th)1 and Th2 cell-mediated immunity in ovalbumin (OVA)-sensitized mice. The objective of this study is to investigate the effects of IONPs on the immune responses of Th17 cells, a subset of T cells involved in various inflammatory pathologies. For in vivo study, a murine model of delayed-type hypersensitivity (DTH) was employed. BALB/c mice received a single dose of IONPs (0.2-10 mg iron/kg) via the tail vein 1 h prior to ovalbumin (OVA) sensitization. Their footpads were subcutaneously challenged with OVA to induce DTH reactions. The expression of Th17 cell-related molecules in inflamed footpads were examined by immunohistochemistry. For in vitro study, OVA-primed splenocytes were directly exposed to IONPs (1-100 μg iron/mL), and then re-stimulated with OVA in culture. The expression of Th17 cell-related molecules were measured by reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay. IONP administration attenuated the number of interleukin (IL)-6, IL-17, the transcription factor ROR-γ, and chemokine receptor 6 positive cells in OVA-challenged footpads, whereas the number of transforming growth factor-β, IL-23 and chemokine (C-C motif) ligand 20 positive cells was not altered. Direct exposure of OVA-primed splenocytes to IONPs suppressed the production of IL-6 and IL-17, and the mRNA expression of IL-17 and ROR-γt. These data indicate that exposure to IONPs attenuates Th17 cell responses in vivo and in vitro.

Nrf2 Regulates the Risk of a Diesel Exhaust Inhalation-Induced Immune Response during Bleomycin Lung Injury and Fibrosis in Mice

The present study investigated the effects of diesel exhaust (DE) on an experimental model of bleomycin (BLM)-induced lung injury and fibrosis in mice. BLM was intravenously administered to both Nrf2^+/+ and Nrf2^−/− C57BL/6J mice on day 0. The mice were exposed to DE for 56 days from 28 days before the BLM injection to 28 days after the BLM injection. Inhalation of DE induced significant inhibition of airway clearance function and the proinflammatory cytokine secretion in macrophages, an increase in neutrophils, and severe lung inflammatory injury, which were greater in Nrf2^−/− mice than in Nrf2^+/+ mice. In contrast, inhalation of DE was observed to induce a greater increase of hydroxyproline content in the lung tissues and significantly higher pulmonary antioxidant enzyme mRNA expression in the Nrf2^+/+ mice than in Nrf2^−/− mice. DE is an important risk factor, and Nrf2 regulates the risk of a DE inhalation induced immune response during BLM lung injury and fibrosis in mice.

Suppressive influence of seasonal influenza epidemic on Kawasaki disease onset

  Kawasaki disease (KD) is an acute systemic vasculitis presenting as an infantile febrile disease. In Japan, the widespread cedar plantation commenced in 1945 has been correlated with the increased incidences of both KD and allergic rhinitis (pollinosis) since the early 1960s. We previously showed that KD was a pollen-induced, delayed-type hypersensitivity that displays biphasic peaks in both summer and winter. KD incidences decrease suddenly around February, particularly after influenza epidemics. Here we investigated the reason for a drastic decrease in KD onsets directly before spring pollen release following rapid increase after autumn pollen release leading to the biphasic pattern. We separately analyzed weekly incidences of KD and influenza in Tokyo (1987-2010) and Kanagawa (1991-2002). Repeated measures for the analysis of variance followed by Bonferroni's multiple comparison tests were performed to compare KD incidence over 3 consecutive weeks, including the weeks when the mean KD prevalence showed the steepest decrease. Next, the week with peak influenza incidence was reset for each year. KD incidence over 3 consecutive weeks, including the new origin week (adjusted week 0), was similarly analyzed. In Tokyo and Kanagawa, KD incidence significantly decreased only after resetting the influenza peak time. These findings suggested that influenza epidemics suppressed KD onset.

Inhaled multiwalled carbon nanotubes modulate the immune response of trimellitic anhydride-induced chemical respiratory allergy in brown Norway rats

The interaction between exposure to nanomaterials and existing inflammatory conditions has not been fully established. Multiwalled carbon nanotubes (MWCNT; Nanocyl NC 7000 CAS no. 7782-42-5; count median diameter in atmosphere 61 ± 5 nm) were tested by inhalation in high Immunoglobulin E (IgE)-responding Brown Norway (BN) rats with trimellitic anhydride (TMA)-induced respiratory allergy. The rats were exposed 2 days/week over a 3.5-week period to a low (11 mg/m(3)) or a high (22 mg/m(3)) concentration of MWCNT. Nonallergic animals exposed to MWCNT and unexposed allergic and nonallergic rats served as controls. At the end of the exposure period, the allergic animals were rechallenged with TMA. Histopathological examination of the respiratory tract showed agglomerated/aggregated MWCNT in the lungs and in the lung-draining lymph nodes. Frustrated phagocytosis was observed as incomplete uptake of MWCNT by the alveolar macrophages and clustering of cells around MWCNT. Large MWCNT agglomerates/aggregates were found in granulomas in the allergic rats, suggesting decreased macrophage clearance in allergic rats. In allergic rats, MWCNT exposure decreased serum IgE levels and the number of lymphocytes in bronchoalveolar lavage. In conclusion, MWCNT did not aggravate the acute allergic reaction but modulated the allergy-associated immune response.

Anandamide attenuates Th-17 cell-mediated delayed-type hypersensitivity response by triggering IL-10 production and consequent microRNA induction

Endogenous cannabinoids [endocannabinoids] are lipid signaling molecules that have been shown to modulate immune functions. However, their role in the regulation of Th17 cells has not been studied previously. In the current study, we used methylated Bovine Serum Albumin [mBSA]-induced delayed type hypersensitivity [DTH] response in C57BL/6 mice, mediated by Th17 cells, as a model to test the anti-inflammatory effects of endocannabinoids. Administration of anandamide [AEA], a member of the endocannabinoid family, into mice resulted in significant mitigation of mBSA-induced inflammation, including foot pad swelling, cell infiltration, and cell proliferation in the draining lymph nodes [LN]. AEA treatment significantly reduced IL-17 and IFN-γ production, as well as decreased RORγt expression while causing significant induction of IL-10 in the draining LNs. IL-10 was critical for the AEA-induced mitigation of DTH response inasmuch as neutralization of IL-10 reversed the effects of AEA. We next analyzed miRNA from the LN cells and found that 100 out of 609 miRNA species were differentially regulated in AEA-treated mice when compared to controls. Several of these miRNAs targeted proinflammatory mediators. Interestingly, many of these miRNA were also upregulated upon in vitro treatment of LN cells with IL-10. Together, the current study demonstrates that AEA may suppress Th-17 cell–mediated DTH response by inducing IL-10 which in turn triggers miRNA that target proinflammatory pathways.

Inflammation and atherosclerosis: direct versus indirect mechanisms

It is now widely accepted that the development of atherosclerotic lesions involves a chronic inflammatory response that includes both innate and adaptive immune mechanisms. However, it is still unclear precisely what induces the inflammatory response. Furthermore, inflammation within the blood vessel can be divided into direct mechanisms where the primary inflammatory events occur within the intima of the blood vessel and contribute to both the initiation and progression of the plaques and indirect mechanisms where inflammation at nonvascular sites can contribute to the progression of the lesions. The direct mechanisms include lipid deposition and modification, influx of lipoprotein associated factors and microparticles derived from many different cell types, and possibly bacterial and viral infection of vascular cells. Indirect mechanisms derive from inflammation related to autoimmune diseases, smoking, respiratory infection, and pollution exposure, and possibly periodontal disease and gastric infection. The mechanisms include secretion of cytokines and other inflammatory factors into the circulation with subsequent uptake into the plaques, egress and recruitment of activated inflammatory cells, formation of dysfunctional HDL and crossreactive autoantibodies.

Effects of diesel exhaust particles on primary cultured healthy human conjunctival epithelium

BACKGROUND

Air pollution from road traffic is a serious public health problem. Epidemiologic studies have demonstrated adverse health effects associated with environmental pollution. Diesel exhaust is a major contributor to ambient particulate matter air pollution. We studied the effects of exposure to diesel exhaust particles on allergic conjunctivitis using cultured conjunctival epithelial cells obtained from healthy people.

OBJECTIVE

To identify the factors involved in the human conjunctival epithelial response to diesel exhaust in vitro.

METHODS

Healthy individuals underwent conjunctival biopsy, and the samples were incubated on conjunctival epithelial sheets. We investigated the effects of exposure to diesel exhaust using GeneChip arrays. The adhesion molecules and cytokines showing increased expression on GeneChip arrays were verified by real-time reverse transcription polymerase chain reaction and enzyme-linked immunosorbent assay.

RESULTS

The GeneChip array showed increased expression of adhesion molecules, cytokines, chemokines, and growth factors after exposure to diesel exhaust. Real-time reverse transcription polymerase chain reaction and enzyme-linked immunosorbent assay confirmed that the expression of intercellular adhesion molecule 1 and interleukin 6, in particular, were significantly upregulated.

CONCLUSION

Our experimental data confirm that exposure to diesel exhaust particles increases inflammatory factor expression in human conjunctiva and thereby contributes to allergic conjunctival responses.

Maternal exposure to carbon black nanoparticle increases collagen type VIII expression in the kidney of offspring

The potential health risks of inhaling nanomaterials are of great concern because of their high specific activity and their unique property of translocation. Earlier studies showed that exposure to nanoparticles through the airway affects both respiratory and extrapulmonary organs. When pregnant mice were exposed to nanoparticles, the respiratory system, the central nervous system and the reproductive system of their offspring were affected. The aim of this study was to assess the effect of maternal exposure to nanoparticles on the offspring, particularly on the kidney. Pregnant ICR mice were exposed to a total of 100 µg of carbon black nanoparticle on the fifth and the ninth days of pregnancy. Samples of blood and kidney tissue were collected from 3-week-old and 12-week-old male offspring mice. Collagen expression was examined by quantitative RT-PCR and immunohistochemistry. Serum levels of creatinine and blood urea nitrogen were examined. Exposure of pregnant ICR mice to carbon black resulted in increased expression of Collagen, type VIII, a1 (Col8a1) in the tubular cells in the kidney of 12-week-old offspring mice but not in 3-week-old ones. The levels of serum creatinine and blood urea nitrogen, indices of renal function, were not different between the groups. These observations were similar to those of tubulointerstitial fibrosis in diabetic nephropathy. These results suggest that maternal exposure to carbon black nanoparticle induces renal abnormalities similar to tubulointerstitial fibrosis in diabetic nephropathy are induced in the kidney of offspring.

Pathological study for the effects of in utero and postnatal exposure to diesel exhaust on a rat endometriosis model

Previous studies have shown that prenatal and postnatal exposure to diesel exhaust (DE), which is known to be one of the main constituents of air pollution, enhances the persistence of endometriosis in a rat model. The aim of this study is to investigate the pathological changes induced by DE exposure in a rat model of endometriosis. Pregnant Sprague-Dawley rats were exposed to DE or clean air beginning on gestational day 2 and neonatal rats were persistently exposed to DE or clean air. Endometriosis was induced by autotransplantation of endometrium onto the peritoneum of eight-week-old female offspring. Endometriotic lesions were examined at 7 and 14 days post-transplantation. As a result, infiltration of activated mast cells remained in deeper area of peritoneal tissue around the endometriosis model compared to the control group at 14 days post-autotransplantation. In the DE exposure group, 14 days post-transplant, the remaining lesions contained fibroblasts and activated mast cells, which were surrounded by collagen fibers. The data showed that prenatal and postnatal DE exposure enhances the activation of mast cells and prolongs the persistence of collagen fibers in the induced rat model of endometriosis.