TREM2 Loss Drives IL-1β+ Macrophage–Mediated Inflammation and Tumor Progression in Pancreatic Cancer

TREM2, a receptor expressed on tumor-associated macrophages (TAMs), plays a critical role in pancreatic ductal adenocarcinoma (PDAC). Researchers explored its function by genetically removing TREM2 in a transgenic mouse model (KPPC;Trem2−/−) to study PDAC progression. Surprisingly, the absence of TREM2 accelerated tumor growth and reduced survival, showing that TREM2 has a protective, anti-inflammatory role rather than promoting cancer.

Single-cell RNA sequencing revealed that TREM2 depletion caused an increase in proinflammatory macrophages, leading to chronic inflammation in the tumor microenvironment. Mechanistic studies identified TREM2 as a key regulator that suppresses the NLRP3/NF-κB/IL-1β inflammasome pathway, preventing excessive inflammatory signaling. Without TREM2, this pathway becomes overactive, driving harmful inflammation.

Additionally, microbial lipopolysaccharide (LPS) from the gut microbiome worsened inflammation in TREM2-deficient mice, further increasing IL-1β levels and accelerating PDAC progression. This highlights the connection between the gut microbiome and cancer-related inflammation.

Importantly, researchers found that blocking IL-1β or depleting the microbiome reversed the rapid tumor progression caused by TREM2 loss, emphasizing the pathogenic role of IL-1β in PDAC. These findings suggest that TREM2 functions as an anti-inflammatory checkpoint, maintaining immune balance by controlling macrophage-driven inflammation.

Clinically, targeting the IL-1β pathway or modulating TREM2 activity could offer new therapeutic strategies to reduce inflammation and improve outcomes in pancreatic cancer patients. This research redefines the role of TREM2 in PDAC and opens the door for novel approaches to combat tumor-promoting inflammation.