Distinct populations of inflammatory fibroblasts and myofibroblasts in pancreatic cancer Pancreatic stellate cells (PSCs) differentiate into cancer-associated fibroblasts (CAFs) that produce desmoplastic stroma, modulating disease progression and therapeutic response in pancreatic ductal adenocarcinoma (PDA). However, it is unknown whether CAFs uniformly carry out these tasks or if subtypes of CAFs with distinct phenotypes in PDA exist. The study identified a CAF subpopulation with elevated expression of α-smooth muscle actin (αSMA) located immediately adjacent to neoplastic cells in mouse and human PDA tissue. This finding was recapitulated in co-cultures of murine PSCs and PDA organoids, and demonstrated that organoid-activated CAFs produced desmoplastic stroma. The co-cultures showed cooperative interactions and revealed another distinct subpopulation of CAFs, located more distantly from neoplastic cells, which lacked elevated αSMA expression and instead secreted IL6 and additional inflammatory mediators. These findings were corroborated in mouse and human PDA tissue, providing direct evidence for CAF heterogeneity in PDA tumor biology with implications for disease etiology and therapeutic development. The study identified two distinct subtypes of CAFs in PDA: myofibroblastic CAFs (myCAFs) and inflammatory CAFs (iCAFs). MyCAFs are located in the periglandular region, adjacent to neoplastic cells, and express high levels of αSMA. iCAFs are more distantly located from neoplastic cells and express high levels of IL6 and other inflammatory cytokines. These subtypes have distinct functional roles in PDA, with myCAFs contributing to stroma production and iCAFs secreting inflammatory factors that promote cancer progression and immune suppression. The study used a novel three-dimensional co-culture system to recapitulate the in vivo interactions between CAFs and cancer cells. This system revealed that PSCs can differentiate into CAFs with distinct phenotypes depending on their environment. The study also demonstrated that CAFs can dynamically switch between different phenotypes based on their spatial and biochemical niche within the PDA microenvironment. The study identified distinct transcriptional profiles for myCAFs and iCAFs, with myCAFs expressing genes associated with myofibroblast function and iCAFs expressing genes associated with inflammatory function. These findings highlight the heterogeneity of CAFs in PDA and suggest that targeting CAFs may require consideration of their distinct subtypes to improve therapeutic outcomes. The study also highlights the need for further investigation into the mechanisms that govern the formation and transition of these cell states.Distinct populations of inflammatory fibroblasts and myofibroblasts in pancreatic cancer Pancreatic stellate cells (PSCs) differentiate into cancer-associated fibroblasts (CAFs) that produce desmoplastic stroma, modulating disease progression and therapeutic response in pancreatic ductal adenocarcinoma (PDA). However, it is unknown whether CAFs uniformly carry out these tasks or if subtypes of CAFs with distinct phenotypes in PDA exist. The study identified a CAF subpopulation with elevated expression of α-smooth muscle actin (αSMA) located immediately adjacent to neoplastic cells in mouse and human PDA tissue. This finding was recapitulated in co-cultures of murine PSCs and PDA organoids, and demonstrated that organoid-activated CAFs produced desmoplastic stroma. The co-cultures showed cooperative interactions and revealed another distinct subpopulation of CAFs, located more distantly from neoplastic cells, which lacked elevated αSMA expression and instead secreted IL6 and additional inflammatory mediators. These findings were corroborated in mouse and human PDA tissue, providing direct evidence for CAF heterogeneity in PDA tumor biology with implications for disease etiology and therapeutic development. The study identified two distinct subtypes of CAFs in PDA: myofibroblastic CAFs (myCAFs) and inflammatory CAFs (iCAFs). MyCAFs are located in the periglandular region, adjacent to neoplastic cells, and express high levels of αSMA. iCAFs are more distantly located from neoplastic cells and express high levels of IL6 and other inflammatory cytokines. These subtypes have distinct functional roles in PDA, with myCAFs contributing to stroma production and iCAFs secreting inflammatory factors that promote cancer progression and immune suppression. The study used a novel three-dimensional co-culture system to recapitulate the in vivo interactions between CAFs and cancer cells. This system revealed that PSCs can differentiate into CAFs with distinct phenotypes depending on their environment. The study also demonstrated that CAFs can dynamically switch between different phenotypes based on their spatial and biochemical niche within the PDA microenvironment. The study identified distinct transcriptional profiles for myCAFs and iCAFs, with myCAFs expressing genes associated with myofibroblast function and iCAFs expressing genes associated with inflammatory function. These findings highlight the heterogeneity of CAFs in PDA and suggest that targeting CAFs may require consideration of their distinct subtypes to improve therapeutic outcomes. The study also highlights the need for further investigation into the mechanisms that govern the formation and transition of these cell states.