Intratumoral microbiota-driven macrophage reprogramming in pancreatic cancer via Blautia metabolite 6-hydroxyhexanoic acid

Pancreatic ductal adenocarcinoma (PDAC) exhibits a particularly immunosuppressive microenvironment, which contributes to its poor prognosis and resistance to conventional therapies. Recent studies have highlighted the microbiome as a dynamic regulator of anti-tumor immunity, ultimately contributing to tumor suppression. The tumor microenvironment is increasingly recognized as a dynamic ecosystem where the microbiome plays a pivotal role in shaping immune responses. Therefore, it is crucial to explore the specific biological processes by which intratumoral microbiome suppresses tumor growth and enhances antitumor immunity. In this study, we identified a significant enrichment of Blautia genus in pancreatic cancer patients with favorable prognosis and revealed its role in modulating macrophage phenotypes within the tumor immune microenvironment. Targeted metabolomics and proteomics uncovered the regulatory correlation between its metabolite, 6-hydroxyhexanoic acid (6-HHA), and tumor-associated macrophages (TAMs) within the tumor microenvironment. Through cellular interventions and animal experiments, we demonstrated via flow cytometry and immunofluorescence imaging that 6-HHA facilitates the phenotypic transition of macrophages from M2 to M1, thereby exerting antitumor effects. RNA-seq analysis elucidated the mechanistic underpinnings by which 6-HHA induces M1 polarization through activation of the JAK1-STAT1 signaling pathway in TAMs. Finally, the addition of a JAK1-STAT1 pathway inhibitor in both in vitro and in vivo experiments attenuated the M1 repolarization effect of 6-HHA, suggesting that the JAK1-STAT1 signaling pathway plays a crucial role in mediating this process. Taken together, Blautia and its metabolite 6-HHA potentiate antitumor immunity through activation of TAMs, which establishes a novel microbiota-targeted therapeutic paradigm for cancer intervention.