# 7-Ketocholesterol promotes T cell migration through Ca2+-NFATc1 pathway-mediated F-actin polymerization and proinflammatory cytokine production in oral lichen planus

## TL;DR

The study finds that 7-ketocholesterol promotes T cell migration in oral lichen planus through a calcium and NFATc1 signaling pathway, contributing to inflammation.

## Contribution

This is the first study to link 7-ketocholesterol to T cell migration in oral lichen planus via Ca2+-NFATc1 signaling and F-actin polymerization.

## Key findings

- 7-ketocholesterol accumulates in OLP plasma and upregulates cholesterol regulators in T cells.
- 7-ketocholesterol enhances T cell migration through Ca2+-NFATc1 signaling and F-actin polymerization.
- Blocking the Ca2+-NFATc1 pathway reduces T cell migration and proinflammatory cytokine production.

## Abstract

Oral lichen planus (OLP) is a chronic T-cell-mediated inflammatory disorder of unknown etiology. Accumulating evidence has demonstrated elevated cholesterol levels in OLP, and its oxidation products --oxysterols have been implicated in T cell dysfunction. However, whether the oxysterol is involved in OLP pathogenesis remains to be fully elucidated.

Metabolomics was performed to profile oxysterols in the plasma of OLP patients, followed by functional enrichment analysis. Single-cell RNA sequencing was utilized to characterize gene expression dysregulation in tissue-resident T cells isolated from OLP lesions. Flow cytometry, immunofluorescence, and qRT-PCR were collectively used to quantify Ca2+ concentration, cell apoptosis, protein expression, intracellular signaling, and gene transcription levels. Functional validation was conducted through a co-culture model and Transwell migration assays to assess the cytotoxic and migratory capacity of OLP T cells.

The oxysterol profiles were aberrant in OLP plasma, with marked accumulation of 7-ketocholesterol (7KC). Functional analysis identified significant enrichment of differential metabolites in androstenedione metabolism. 7KC upregulated the expression of cholesterol regulators (SREBP2/LXR) in OLP T cells. Pro-7-ketocholesterogenic gene sets were dysregulated in OLP tissues, with localized T cells exhibiting enriched Ca2+ -NFATc1 signaling and coordinated F-actin polymerization/ITGAL (LFA-1α) upregulation, positively correlating with migration signatures. Peripheral OLP T cells showed elevated Ca2+, nuclear NFATc1, F-actin polymerization, and LFA-1α, all of which, along with ITGAL/IL1B/CCL4/IL6 levels, were further potentiated by 7KC treatment. 7KC was confirmed to enhance migrations of primary OLP T cells and OLP plasma-pretreated Jurkat T cells toward LPS-treated keratinocytes, without affecting keratinocyte apoptosis. Furthermore, CM4620-mediated blockade of Ca2+ -NFATc1 pathway in OLP T cells inhibited 7KC-induced NFATc1 activation, reduced the expressions of F-actin and its modulators ACTB/DIAPH1, and IL1B/CCL4/IL6 gene expressions, with migration suppressions of both primary OLP T cells and OLP plasma-pretreated Jurkat T cells.

7KC could promote T cell migration through Ca2+ -NFATc1 pathway-mediated F-actin polymerization and expression of IL1B/CCL4/IL6 in OLP.