Akkermansia muciniphila activates natural killer cells by suppressing the TGF-β signaling pathway in lung adenocarcinoma cells

Lung adenocarcinoma (LUAD) stands out as a prevalent malignant tumor necessitating innovative strategies to enhance therapeutic outcomes. Akkermansia muciniphila (AKK) has emerged as intricately linked to tumor immunotherapy, yet its impact on natural killer (NK) cells, which play a crucial role in immunotherapy, remains unclear. This study aims to investigate the effects of AKK outer membrane proteins on NK cells in LUAD and elucidate potential associated molecular mechanisms. 16S rRNA sequencing was employed to analyze bacterial genera and their abundance in fecal samples from LUAD patients. Co-culturing of NK-92 cells with LUAD cells, with or without treatment of AKK outer membrane protein Amuc_1100, was conducted to investigate the mechanisms of AKK on LUAD. Additionally, a xenograft mouse model was established to validate the effects of AKK in an in vivo setting. The experimental findings indicated that LUAD patients with elevated AKK levels in their fecal samples demonstrated increased NK cell infiltration and reduced TGF-β levels. Treatment with Amuc_1100 elevated TNF-α and IL-15 cytokine levels, decreased TGF-β levels and proteins associated with TGF-β pathway, enhanced NK cell cytotoxicity, upregulated perforin and granzyme B expression, induced apoptosis and cell cycle arrest, thereby inhibiting cancer cell proliferation. Amuc_1100 also impeded tumor growth in vivo. In summary, these results suggest that AKK activates NK cells to target tumor cells by suppressing the TGF-β signaling pathway in LUAD cells, underscoring the potential of Akk as an effective immunotherapeutic agent in LUAD NK cell-directed therapies.