Intratumoral Bacillus cereus orchestrates stem-like lymphoid niches to potentiate immunotherapy response in hepatocellular carcinoma.

Abstract

Tertiary lymphoid structures (TLSs) drive antitumor immunity, but their functional heterogeneity translates into inconsistent immunotherapy responses in hepatocellular carcinoma (HCC), raising the question of which immune niches actually predict efficacy. Using spatial multi-omics analysis, we uncover a distinct niche, the stem-like lymphoid niches (SLNs), that correlates with stronger responses to PD-1/PD-L1 blockade. Unlike conventional TLS, SLNs feature a specialized niche of CD70+ type 2 innate lymphoid cells (ILC2s) and progenitor exhausted T (Tpex) cells. Intriguingly, intratumoral Bacillus cereus promotes SLN accumulation via triggering endothelial IL-33 release, which rewires ILC2s metabolism and enhances H3K4me3-mediated epigenetic activation of CD70, Lta, and Ltb genes, reinforcing the niche's lymphoid-organizing function. We identify the bacterial phosphoinositide-specific phospholipase C (PI-PLC) as the effector behind this endothelial IL-33 release. Combining PI-PLC with αPD-L1 synergistically amplifies antitumor immunity, highlighting SLNs as a promising target for boosting immunotherapy in HCC.