Regulation of antibody-mediated effector functions

PROJECT SUMMARY lgG perform immunomodulatory signaling via lgG Fe-Fey receptor (FcyR) interactions that trigger different effector functions according to the balance of activating to inhibitory (A/I) signals. Non-neutralizing, FcyR- mediated effector functions can be critical for optimal protection in many infectious diseases, including both influenza viruses and SARS-CoV-2. Studies over the past decade have shown tremendous heterogeneity in lgG Fe domains across individuals, with Fe domain structure (both protein and glycan components) being one key determinant of effector functions that are engaged during an infection. Yet, it is clear from clinical studies showing variable efficacy of monoclonal antibody (mAb) therapeutics with homogenous Fe domains that Fe domain structure is not the sole determinant of antibody effector function in vivo. The functional capacity of effector cells is almost certainly a critical determinant of lgG activity in vivo, but this has not been defined. This proposal addresses key unanswered questions in immunity mediated by broad, FcyR-dependent antibodies against influenza viruses and SARS-CoV-2: 1) how much heterogeneity exists in the functional capacity of human effector cells and is function altered by influenza virus or SARS-CoV-2 vaccination or infection, 2) how do obesity and diabetes - states that confer high risk during influenza virus or SARS-CoV-2 infections - impact effector cell function 3) can the functional capacity of hypo- or hyperresponsive effector cells be "tuned" using lgG engineering strategies. We will address these questions in experiments that include key collaborations with Project 2 (Barnes), Project 3 (Khatri) and the Technology Project (Davis). Designed immunogen baits via Project 2 will be used to pull out broadly reactive, anti-influenza and SARS-CoV-2 lgG from polyclonal antisera to study the effector functions recruited by these antibodies. Effector cells will furthermore be subject to transcriptomics before and after treatment with lgG immune complexes to define correlates for responses through collaboration with Project 3. In collaboration with the Technology Project we will use spleen, tonsil, and lung organoids to test the hypothesis that effector cell functions can be "tuned" using engineered lgG immune complexes. Finally, to follow up on our observation from humans that effector cell function is heterogeneous across individuals, we will use different collaborative cross mouse strains to test the hypothesis that the ability of broad, non-neutralizing anti-influenza mAbs to protect is correlated with the functional capacity of their effector cells (collaboration between Dr. Taia Wang and Dr. David Schneider). Collectively, this work, alongside the other projects proposed, helps to establish a rigorous immunological foundation for factors underlying protection against influenza virus and SARS-CoV-2.