A change in CD3γ, CD3δ, CD3ϵ, and CD3ζ gene expression in T-lymphocytes from benzene-exposed and benzene-poisoned workers

Benzene-associated immunosuppression and chronic inflammation in humans: a systematic review

OBJECTIVE

Recent evidence has accumulated that the immune system is intimately intertwined with cancer development. Two key characteristics of carcinogens in which the immune system plays a central role are chronic inflammation and immunosuppression. In this systematic review, we investigated the association of chronic inflammatory and immunosuppressive outcomes with benzene, a widely used industrial chemical. Benzene has been confirmed to cause acute myeloid leukaemia and suspected to cause non-Hodgkin lymphoma, two cancers of the blood-forming system that affect immune cells.

METHODS

We systematically searched PubMed and Embase for all relevant studies using a combination of Medical Subject Headings (MeSH) and selected key words. The detailed review protocol, including search strategy, was registered with PROSPERO, the international prospective register of systematic reviews (#CRD42019138611).

RESULTS

Based on all human studies selected in the final review, we report new evidence of a benzene-induced immunosuppressive effect on the adaptive immune system and activation of the innate immune system to cause inflammation. In particular, benzene significantly lowers the number of white blood cells, particularly lymphocytes such as CD4+ T-cells, B-cells and natural killer cells, and increases proinflammatory biomarkers at low levels of exposure.

CONCLUSION

To the best of our knowledge, this is the first comprehensive review of benzene's immunotoxicity in humans. Based on results obtained from this review, we propose two potential immunotoxic mechanisms of how benzene induces leukaemia/lymphoma: (1) cancer invasion caused by proinflammatory cytokine production, and (2) cancer promotion via impaired immunosurveillance. Further studies will be required to confirm the connection between benzene exposure and its effects on the immune system.

Epimedium Polysaccharide Ameliorates Benzene-Induced Aplastic Anemia in Mice

Benzene (BZ) is an important occupational and environmental pollutant. Exposure to BZ may cause aplastic anemia which is characterized as bone marrow hematopoietic failure. In order to reduce the harmful effects of this pollutant, it is necessary to identify additional preventative measures. In this study, we investigated the protective effects of epimedium polysaccharide (EPS), a natural compound with antioxidant and immune-enhancing potency, on aplastic anemia induced by benzene exposure in mice. Male CD-1 mice were randomly divided into five groups including control, BZ (880 mg/kg), LE (EPS low-dose, 20 mg/kg + BZ), ME (EPS middle-dose, 100 mg/kg + BZ), and HE (EPS high-dose, 200 mg/kg + BZ) groups. Animals were exposed to BZ by subcutaneous injection in the presence or absence of EPS via oral administration. All mice were treated 3 times a week for 8 consecutive weeks to develop a mouse model of benzene-induced aplastic anemia (BIAA). Results showed that BZ induced a significant decrease in both white and red blood cells, platelet counts, and hemoglobin level compared with that in the control group (p < 0.01). Treatment of EPS led to a protective effect against these changes particularly in the highest-dose group (HE, p < 0.01). EPS also recovered the decreased number of nucleated cells in peripheral blood cell smears and femur biopsies by BZ exposure. The increased level of reactive oxygen species (ROS) in bone marrow mononuclear cells (BMMNCs) in mice from the BZ group was significantly lower (p < 0.01) in the mice from the highest concentration of EPS (HE) group when compared with that from the control group. In addition, BZ exposure led to a significant increase in the apoptosis rate in BMMNCs which was prevented by EPS in a dose-dependent manner (p < 0.01). The antiapoptosis effect of EPS was through reversing apoptotic proteins such as BAX, Caspase-9 and Caspase-3, and Bcl-2. Finally, EPS treatment partially restored the levels of T cells and the different subtypes except CD80⁺ and CD86⁺ compared with the BZ group (HE, p < 0.05). These results suggest that EPS has protective effects against BIAA via antioxidative stress, immune modulation, and antiapoptosis mechanisms.

Epimedium polysaccharides attenuates hematotoxicity by reducing oxidative stress and enhancing immune function in mice model of benzene-induced bone marrow failure

Chronic benzene (BZ) exposure is associated with multiple adverse health effects and leads to progressive bone marrow failure (BMF). BZ-induced BMF is an acquired aplastic anemia characterized by severe anemia, neutropenia and thrombocytopenia, which is likely caused by immunotoxicity and oxidative stress. Previous studies showed that Epimedium polysaccharides (EPS), a natural and major herbal compound derived from Epimedium, has immunomodulatory and antioxidant potential. The purpose of this study was to evaluate the potential efficacy of EPS against BZ-induced BMF. BMF mouse model was established by subcutaneous injection of 2 ml/kg BZ in CD1 mice. Mice received daily oral treatment with 100 mg/kg high-dose EPS and 20 mg/kg low-dose EPS for four weeks. Our data showed that EPS treatment alleviated BZ-associated weight loss and increased the number of whole blood cells in peripheral blood and nucleated cells in bone marrow. Furthermore, EPS treatment decreased apoptotic rate and reactive oxygen species production, S-phase arrest in bone marrow cells. Finally, EPS treatment improved T cell-mediated immune suppression by increasing CD3+, CD4 + T-cell counts, and CD4+/CD8+ ratio. and modulated hematopoietic cytokines including EPO, IL-11, and IL-2 in peripheral blood. Our study suggests that EPS is a potential therapeutic target to attenuate hematotoxicity induced by BZ.

Benzene-Induced Aberrant miRNA Expression Profile in Hematopoietic Progenitor Cells in C57BL/6 Mice

Benzene is a common environmental pollutant that causes hematological alterations. MicroRNAs (miRNAs) may play a role in benzene-induced hematotoxicity. In this study, C57BL/6 mice showed significant hematotoxicity after exposure to 150 mg/kg benzene for 4 weeks. Benzene exposure decreased not only the number of cells in peripheral blood but also hematopoietic progenitor cells in the bone marrow. Meanwhile, RNA from Lin⁻ cells sorted from the bone marrow was applied to aberrant miRNA expression profile using Illumina sequencing. We found that 5 miRNAs were overexpressed and 45 miRNAs were downregulated in the benzene exposure group. Sequencing results were confirmed through qRT-PCR. Furthermore, we also identified five miRNAs which significantly altered in Lin⁻c-Kit⁺ cells obtained from benzene-exposed mice, including mmu-miR-34a-5p; mmu-miR-342-3p; mmu-miR-100-5p; mmu-miR-181a-5p; and mmu-miR-196b-5p. In summary, we successfully established a classical animal model to induce significant hematotoxicity by benzene injection. Benzene exposure may cause severe hematotoxicity not only to blood cells in peripheral circulation but also to hematopoietic cells in bone marrow. Benzene exposure also alters miRNA expression in hematopoietic progenitor cells. This study suggests that benzene induces alteration in hematopoiesis and hematopoiesis-associated miRNAs.

Characteristics of TCRζ, ZAP-70, and FcɛRIγ gene expression in patients with T- and NK/T-cell lymphoma

Abnormal expression of key signaling molecules and defective T-cell function play a crucial role in the pathogenesis of T-cell immunodeficiency in hematological malignancies. To understand the molecular basis of T-cell signaling abnormalities and TCRζ chain deficiencies in T- and NK/T-cell lymphoma, the expression level of the TCRζ, ZAP-70, and FcɛRIγ genes in peripheral blood mononuclear cells from 25 patients with T-cell lymphoma, 16 patients with NK/T-cell lymphoma (NK/T-CL), and 26 healthy individuals was determined. In addition, their relationship with disease stage and TCRζ 3' untranslated region (3'UTR) splice variants was analyzed in this study. The expression level of all three genes was significantly altered with disease progression, and a decreasing trend was found in patients compared with healthy controls. TCRζ and ZAP-70 were significantly positively related in all samples, and a negative relationship between TCRζ and FcɛRIγ was significantly lost in NK/T-CL patients. Moreover, distinct expression patterns were defined for patient groups with different TCRζ 3'UTR isoforms. In conclusion, a lower expression pattern for all three genes may indicate a weaker immune status based on reduced TCRζ and ZAP-70 expression without the complementary effects of FcɛRIγ, while aberrant TCRζ 3'UTR splicing may contribute to T-cell receptor (TCR) signaling regulation in T cells from patients with T- and NK/T-cell lymphoma.