Neuronal and Progenitor/Stem Cell Function During Salivary Gland Development Funded Grant uri icon

description

  • In order to investigate the identities, lineage relationships and functions of salivary progenitor cells we generated a single-cell RNAseq analysis of murine salivary gland development at stages corresponding to endbud initiation, branching morphogenesis, cytodifferentiation, postnatal development and adult homeostasis. This project provided us with an atlas of the transcriptional landscape of murine salivary gland development. Bioinformatic trajectory analysis suggested that acinar populations represent the most differentiated state relative to other populations from the same developmental stage. Acinar differentiation involved a decrease in expression of numerous transcription factors, including Ybx1, Eno1, Atf3, and Atf4. This resource provided us with specific markers to identify and characterize two subsets of intercalated duct cells: a subset defined by Gfra3 and Kit, and a subset defined by Gstt1 with sexually dimorphic Smgc co-expression in females and high Serpinb11 co-expression in males. Trajectory analysis suggested the Gstt1+ population originates from proacinar precursors suggesting plasticity in this population. This organ-specific atlas can be compared with other similar resources to investigate specific cell functions and predict common mechanisms involved in development of branching organs. In order to develop regenerative therapies using the information we gain from studying development, we have focused on the parasympathetic nerves, which are a vital component of the progenitor niche during organogenesis. In addition, injured adult organs do not regenerate after parasympathectomy, and there are few treatments to improve organ regeneration or prevent damage, particularly that caused by therapeutic irradiation. Head and neck cancer patients treated with radiotherapy often suffer from salivary gland hypofunction, which causes significant morbidity and loss of quality of life. Preventing hypofunction is an unmet therapeutic need. We previously identified the neurotrophic factor, neurturin, as being critical for parasympathetic innervation of murine submandibular glands during early gland development. In recent experiments we used an AAV2 vector expressing human neurturin (CERE-120) to treat murine submandibular glands either pre- or post-irradiation (IR). Treatment with CERE-120 pre-IR, not post-IR, prevented hypofunction. RNAseq analysis showed reduced gene expression associated with fibrosis and the innate and humoral immune responses. We then used a minipig model with CERE-120 treatment pre-IR and also compared outcomes of the contralateral non-IR gland. Analysis of gene expression, morphology and immunostaining showed reduced IR-related immune responses and improved secretory mechanisms. CERE-120 prevented IR-induced hypofunction, restored immune homeostasis and there was a coordinated contralateral gland response to either damage or treatment. CERE-120 gene therapy is a potential treatment for head and neck cancer patients to influence communication among neuronal, immune, and epithelial cells to prevent IR-induced salivary hypofunction and restore immune homeostasis.