DAMP-inducing Peptide Nanofibers and PAMP Combination Adjuvants Boost Functional Lung Tissue-resident Memory CD4+ T Cell Responses

Abstract

Vaccine adjuvants are typically composed of pathogen-associated molecular patterns (PAMPs) or danger-associated molecular patterns (DAMPs) that activate innate immune cells. Advances in basic immunology have demonstrated the need for various types of protective immunity, which are difficult to achieve with a single adjuvant. The FDA approval of multiple PAMP-DAMP combinations for clinical use has led to an increased momentum in the area in recent years. Here we report the use of DAMP-inducing peptide nanofibers (PNFs) and CL429 (PAMP) combinations as subunit boosters for Bacille Calmette-Guerin (BCG). We demonstrate that pulmonary boosting with PNFs and CL429 enhances the lung-resident memory phenotype, effector cytokine profiles, and transcription factor bias of antigen-specific CD4+T cell populations compared to PNFs alone. Importantly, the combination significantly improved the frequency of tissue-resident memory T (TRM) cells which, have been shown to provide superior protection compared to circulating memory T cells. Interestingly, the T helper (Th) subset profile was driven in part driven by the route of vaccination resulting in a Th17 bias via a mucosal route or a Th1 bias when delivered intravenously. We show that following pulmonary administration, lung-resident antigen presenting cells (APCs) efficiently internalize PNFs and upregulate important co-stimulatory markers that drive T cell priming and activation. Our findings suggest that heterologous booster vaccines composed of DAMP-inducing PNFs and PAMP combinations can engage innate and adaptive immunity for generating TRM cells that protect against TB and potentially other respiratory diseases.