Ex Vivo Human Colon Tissue Exposure to Pristine Graphene Activates Genes Involved in the Binding, Adhesion and Proliferation of Epithelial Cells

Abstract

Toxicology studies on pristine graphene are limited and lack significant correlations with actual human response. The goal of the current study was to determine the response of total colonic human tissue to pristine graphene exposure. Biopsy punches of colon tissues from healthy human were used to assess the biological response after ex vivo exposure to graphene at three different concentrations (1, 10, and 100 µg/mL). mRNA expression of specific genes or intestinal cytokine abundance was assessed using real-time PCR or multiplex immunoassays, respectively. Pristine graphene-activated genes that are related to binding and adhesion (GTPase and KRAS) within 2 h of exposure. Furthermore, the PCNA (proliferating cell nuclear antigen) gene was upregulated after exposure to graphene at all concentrations. Ingenuity pathway analysis revealed that STAT3 and VEGF signaling pathways (known to be involved in cell proliferation and growth) were upregulated. Graphene exposure (10 µg/mL) for 24 h significantly increased levels of pro-inflammatory cytokines IFNγ, IL-8, IL-17, IL-6, IL-9, MIP-1α, and Eotaxin. Collectively, these results indicated that graphene may activate the STAT3–IL23–IL17 response axis. The findings in this study provide information on toxicity evaluation using a human-relevant ex vivo colon model and serve as a basis for further exploration of its bio-applications.

Ginsenoside Rg3 Reduces the Toxicity of Graphene Oxide Used for pH-Responsive Delivery of Doxorubicin to Liver and Breast Cancer Cells

“…VEGF can also induce cellular processes that are common to many growth factor receptors, including cell migration, expansion, development, and proliferation. In fact, the activation of both of these pathways is indicative of an increase in cell proliferation after exposure to GO ( Figure 2 b), which is similar to the previous report about the cell proliferative effect of pristine graphene [ 61 ]. This can also be supported by increased cell proliferation and growth in numerous cell lines (MCF-7, HepG2, A549, and HeLa cells) treated with pristine graphene [ 63 ].…”

“…Among these, interleukin 17 receptor A (IL17RA) is the receptor for IL17A that is the major proinflammatory cytokine secreted by activated T-lymphocytes. In fact, IL-17 communicates with JAK-STAT family signaling, particularly STAT3 [ 61 ]. Furthermore, IL-17 showed a positive association with vascular endothelial growth factor ( VEGF ) expression and signaling [ 62 ], which is similar to our observations about the overexpression of VEGF by GO, as shown in the angiogenesis genes subset in Figure S4 .…”

Environmental and Health Impacts of Graphene and Other Two-Dimensional Materials: A Graphene Flagship Perspective

“…Inflammatory responses of GBMs in the GI tract and adverse effects on the intestine in the state of inflammation were addressed in several recent studies. Lahiani et al 347 exposed ex vivo human colon tissue to graphene (1− 1.2 nm thick, ≤10 μm lateral size), which resulted in an activation of genes involved in the binding, adhesion (e.g., GTPase and KRAS) and proliferation of epithelial cells (e.g., PCNA, STAT3) within 2 h as well as increased levels of proinflammatory cytokines IFN, IL-8, IL-17, IL-6, IL-9, MIP-1, and Eotaxin within 24 h. 347 These results suggest that pristine graphene may activate the STAT3-IL-23-IL-17 inflammatory response in the gut. Two further studies assessed the inflammatory responses of GO on intestinal epithelial cells in vitro (e.g., NCM460 and FHC human colon epithelial cell lines) and in a mouse model of colitis in vivo.…”