Some non-sensitizers upregulate CD54 expression by activation of the NLRP3 inflammasome in THP-1 cells

Abstract

The human cell line activation test (h-CLAT) is a skin sensitization test that measures the expression of cell surface proteins CD86 and CD54 to evaluate the skin sensitization potential of test chemicals. However, some skin irritants have been reported to induce dramatically high CD54 expression leading to false-positive h-CLAT results. Furthermore, CD54 expression is strongly induced by cytokines, such as interleukin (IL)-1β and tumor necrosis factor (TNF)-α, or danger signals that activate its signaling pathways. In this study, we focused on the relationship between CD54 expression and the Nucleotide binding domain, leucine-rich-containing family, pyrin domain containing 3 (NLRP3) inflammasome, a protein complex that plays a pivotal role in intra-cellular inflammation. We observed the activation of caspase-1 and production of IL-1β after exposure of THP-1 cells to 2,4-dinitrochlorobenzene (DNCB, sensitizer), octanoic acid (OA, non-sensitizer), and salicylic acid (SA, non-sensitizer), implying NLRP3 activation. These observations confirmed the activation of the inflammasome by CD54-only positive chemicals. CD54 expression, induced by OA and SA, was suppressed by potassium chloride, a typical inhibitor of NLRP3 inflammasome activation. These results suggested that the NLRP3 inflammasome may be activated in THP-1 cells resulting in the expression of CD54, and subsequently leading to false-positive results.

Co-Culture of THP-1 Cells and Normal Human Epidermal Keratinocytes (NHEK) for Modified Human Cell Line Activation Test (h-CLAT)

“…Rossol et al provided evidence that increased extracellular Ca 2+ ions can activate the NLRP3 inflammasome, which plays a role in controlling skin sensitization [30] in monocytes [31]. Mitachi et al reported that the NLRP3 inflammasome is involved in the upregulation of CD54 expression in THP-1 cells [32]. Corresponding to these published data, our results revealed that high Ca 2+ in the KI medium may enhance CD54 expression in THP-1 cells.…”

Performance of a novel in vitro assay for skin sensitization based on activation of T lymphocytes

“…5). It was reported that salicylic acid induced an increase in CD54 expression in THP-1 cells by activation of NLRP3 inflammasomes (Mitachi et al, 2019). Considering that these positive results for sodium lauryl sulfate and salicylic acid appear to relate to different key events of skin sensitization, the relevance of the false-positive results in our study is unclear.…”

Results of Complex Immunopharmacological Analysis of the Mechanisms of Action of Bioregulation Agents

“…Another functional lymphocyte marker CD54 (ICAM-1) correlated with the severity of the inflammatory process, because CD54 expression is known to be induced by such cytokines as interleukin IL-1β and TNFα [14]. In patients with infectious inflammatory process, the number of CD54 + cells was consistently increased by almost 2-fold in comparison with the reference values (to 10.37±0.42% vs 5.49±0.98% in controls).…”