Hu, Jie

Background/Objectives: Heterotopic ossification (HO), the aberrant formation of bone within soft tissues, arises either from rare genetic mutations or more commonly from traumatic insults. It is a major cause of morbidity not only in individuals harboring causative mutations, but also in those undergoing musculoskeletal surgery or trauma and in soldiers sustaining blast or burn injuries. Bone morphogenetic protein (BMP) signaling is a central driver of both hereditary and acquired forms of HO. Primary cilia are nonmotile, antenna-like organelles that extend from the cell surface and serve as crucial sensory and signaling hubs by concentrating key pathway components within a confined volume at the ciliary tip. However, their functional role in the pathogenesis of traumatic HO remains poorly understood. Methods: We investigate the role of primary cilia in traumatic HO using a genetically modified mouse model and cellular model. Results: We demonstrate that BMP signaling is attenuated when primary cilia function is disrupted. Both ciliation frequency and ciliary length were reduced in Scleraxis-CreERT2; Intraflagellar transport 88 floxed/floxed (Scx-CreERT2;Ift88fl/fl) tenocytes. Deletion of Ift88 effectively suppressed pathological BMP signaling and inhibited HO formation. Conclusions: These findings establish that functional primary cilia are required for traumatic HO development and highlight ciliary regulation as a potential therapeutic avenue for preventing or mitigating post-traumatic HO.

Abstract Background: Hemorrhagic necrotizing pancreatitis (HNP) is a highly lethal form of pancreatitis that lacks mechanism-based therapy. Intra-acinar enzyme activation is fundamental to pancreatitis initiation, yet it does not explain why only a subset of episodes progress to catastrophic hemorrhagic necrosis. Objective: To identify determinants of progression to lethal HNP and test a mechanism-based preventive intervention. Design: Using humanized trypsinogen mouse models and secretagogue regimens, we compared high-dose cerulein with low/moderate-dose cerulein and bombesin. We quantified pancreatic protease activity, performed blinded histopathologic scoring, assessed hemorrhage/vascular disruption, and evaluated enzyme localization and ductal injury by PRSS1 immunostaining. De-identified human pancreatic histology from HNP were examined. We tested a repurposed strategy using clinically approved agents for other indications: secretin to stimulate ductal fluid secretion and isosorbide mononitrate (ISMN) to promote ductal outflow via sphincter of Oddi relaxation. Results: High-dose cerulein induced robust intrapancreatic protease activation but predominantly caused edematous pancreatitis. Paradoxically, bombesin and low/moderate-dose cerulein elicited lower total pancreatic protease activity yet produced severe, frequently lethal HNP with vascular disruption and lobular ischemic necrosis. HNP was associated with intraductal enzyme accumulation and ductal injury. Secretin or ISMN alone showed limited protection, whereas combined secretin+ISMN prevented hemorrhagic necrotizing injury. Conclusion: Pancreatitis severity is determined not only by the magnitude of enzyme activation but also by where enzyme activity is exerted, implicating intraductal enzyme accumulation as a mechanistic determinant and therapeutic target in HNP. Coordinated enhancement of ductal secretion and outflow with clinically approved agents prevents HNP in vivo, supporting a translatable prevention strategy.