Protein engineering approaches towards respiratory disease prevention and therapeutics

Abstract

For decades, protein engineering has achieved tremendous advances in diseases prevention and treatment. In this dissertation, we introduced the design and development of protein-based platforms to address respiratory diseases: Non-small cell lung cancer and COVID-19. In the first part of this work, certain solid tumors, such as non-small cell lung cancer (NSCLC) bears high somatic mutation frequencies, which are often coupled with increased tumor immunogenicity and high levels of tumor-infiltrating lymphocytes. However, tumor cells can often evade the host's immune surveillance through elaborate mechanisms, involving tumor cell-intrinsic events. One mechanism that impedes efficacious anti-tumor response is silencing of expression of stimulator of interferon genes (STING) in tumor cells. In this section, we engineered the immune adaptor STING as a protein-based delivery system to efficiently encapsulate and intracellular deliver cyclic dinucleotides (CDNs). Through genetic fusion with a protein transduction domain, the recombinant STING can spontaneously penetrate cells to markedly enhance the delivery of CDNs in a mouse vaccination model and a syngeneic mouse tumor model. Moreover, motivated by recent findings that certain tumor cells can evade immune surveillance via loss of STING expression, we further unveiled that our STING platform can serve as a functional vehicle to restore the STING signaling in a panel of lung and melanoma cell lines with impared STING expression. Therefore, our STING-based protein delivery platform may offer a unique direction towards targeting STING-silenced tumors as well as augmenting the efficacy of STING-based vaccine adjuvants. In the second part, the highly transmissible coronavirus SARS-CoV-2 has infected more than 140 million people and has claimed almost 3 million lives globally to date. Despite quarantines and lockdowns that help curb viral transmission, safe and effective preventative measures remain urgently needed. Here, we presented a protein engineering strategy to control the ongoing Coronavirus disease 2019 (COVID-19) pandemic. After devising a protein-based agent by fusing an antiviral nanobody to a cellulose-binding domain and confirming its high yield from bacterial culturing, we validated its capability to bind cellulose products. With presented functions in capturing and neutralizing SARS-CoV-2, we therefore conclude our fusion protein is a promising candidate to intervene against COVID-19.--Author's abstract