Intranasal adjuvant immunotherapy increases survival in murine metastatic Lymphangioleiomyomatosis (LAM)

Abstract

Pulmonary lymphangioleiomyomatosis (LAM) is a slow progressing, metastasizing neoplasm primarily affecting women of reproductive age. LAM is characterized by the abnormal growth of smooth muscle-like cells leading to cystic destruction of the lungs. Rapamycin, the only FDA approved treatment for LAM, slows disease progression but patient responses are incomplete. Therefore there is a critical need for new LAM treatments. Research has shown that LAM has several characteristics of cancer including suspected immune suppression. We and others recently found that LAM may be treated using immune checkpoint inhibitors (ICI), a common cancer immunotherapy. Here, we investigate immune-activating adjuvants as local anti-LAM immunotherapies. Using an established murine model of metastatic LAM, we determined survival after twice weekly intranasal treatments of CpG, PolyI:C, or MPLA. We used flow cytometry and immunofluorescence to determine how adjuvants alter the immune response in LAM. We found that intranasal treatment with CpG and PolyI:C, but not MPLA, increased survival in mice with LAM. In more progressive LAM disease, we observed an increase in activated CD8 T cells, and a decrease in B cell, macrophage, and eosinophil infiltration in lungs of CpG treated vs untreated LAM mice. We also observed increased expression of MHC-II on alveolar macrophages but decreased numbers of migratory dendritic cells in CpG treated LAM lungs. These results suggest that CpG immunotherapy in LAM lungs activates cytotoxic lymphocytes while tempering other inflammatory cells like eosinophils. Our findings also suggest that LAM lungs may respond favorably to adjuvant immunotherapy, and that combination ICI-adjuvant therapy could be synergistic.