Targeting MLCK1 uncouples immune checkpoint inhibitor-induced colitis from antitumour immunity.
Journal
Gut
ISSN
1468-3288
Date Issued
2026-01-06
Author(s)
Xiong, Lei
Huang, Jianshang
Dong, Yunsheng
Han, Wei
Xu, Wentao
Han, Yiran
An, Chenchen
Zhu, Rumeng
Zhu, Nina
Xia, Hanqi
Rahman, Abduxukur
Tang, Sainan
Jiang, Chonggui
Zhao, Junhao
Pei, Wangxiang
Wang, Juan
Wang, Xianda
Song, Jiayi
Wang, Zihan
Wu, Shanshan
Zhang, Hui
Xu, Honghai
Wu, Baoming
Huang, Qiansheng
Bao, Bin
Mei, Qiao
Zhu, Huaqing
Hou, Lanlan
Liangpunsakul, Suthat
Cao, Feng
Weng, Honglei
Tan, Bei
Turner, Jerrold R
Wang, Hua
Zuo, Li
Abstract
Immune checkpoint inhibitors (ICIs) have revolutionised cancer treatment and patients' survival. However, ICIs also cause severe immune-related adverse events, notably colitis, resulting in ICIs therapy discontinuation and tumour immunotherapy failure. This study investigates long myosin light chain kinase 1 (MLCK1), a known regulator of tight junction and gut permeability, to elucidate the mechanisms underlying ICI-mediated colitis and identify approaches to reduce this toxicity.
This study employed an integrated approach, using clinical samples, in vivo models and in vitro organoid systems. Biopsies from patients with ICIs colitis were profiled using single-cell RNA sequencing (scRNA-seq) and spatial transcriptomics. To recapitulate human ICIs colitis, we used a wild mouse microbiota (WildR) model, alongside various genetically modified and tumour-bearing models (including melanoma and MC38). Furthermore, mechanisms were investigated through organoid-immune cell co-cultures. Finally, surface plasmon resonance, microscale thermophoresis, full-spectrum flow cytometry, bulk RNA sequencing, immunostaining, ELISA and gut permeability assays were performed to comprehensively delineate the underlying molecular mechanism.
Tight junction integrity was compromised in both human ICIs colitis and our WildR mouse model. We determined that this barrier dysfunction is driven by activation of the MLCK1-mediated leak pathway following ICI treatment. Using murine models, we identified tumour necrosis factor secreted by CD8 and CD4 T cells as an upstream regulator that induces colitis through this MLCK-dependent mechanism, as genetic deletion of MLCK preserved the tight junction structure and ameliorated the inflammation and ICIs colitis. Furthermore, a pharmacological screen identified the small molecule Epicatechin, which blocks MLCK1-FKBP8 interaction and inhibits the recruitment of MLCK1 to the perijunctional actomyosin ring and prevents the intestinal barrier loss. Finally, treatment with Epicatechin mitigated ICI-induced colitis without compromising the antitumour efficacy of the immunotherapy.
These findings suggest that MLCK1-dependent tight junction regulation is essential for ICIs colitis, positioning barrier restoration as a potential therapeutic strategy.
Subjects
GUT INFLAMMATION
IMMUNOTHERAPY
TIGHT JUNCTION
Type
journal article