Uncovering immune network principles driving humoral immunity in inflammatory conditions

PROJECT SUMMARY/ABSTRACT B cells participate in germinal center (GC) reactions to generate high-affinity antibodies, which represent a crucial line of protection from viruses and other pathogens. To date, the mechanism by which the highest-affinity B cell clones are selected remains elusive. Vital to the development of these high-affinity clones are T follicular helper (Tfh) cells, which stimulate B cells to undergo GC selection through an interaction known as T cell help. While our understanding of T cell help dynamics in single-antigen GCs has significantly increased over the last few years, less is understood about the distribution of Tfh cell help in inflammatory conditions such as viral infections or cancer. Importantly, GC-like clusters referred to as tertiary lymphoid structures (TLSs) have been a subject of recent interest, as chronic respiratory viral infections and many cancers and are accompanied by TLS formation. Notably, the occurrence of TLSs in cancer patients correlates – with some exceptions - with increased responsiveness to immunotherapy. However, most studies are limited to describing the appearance of TLS and how their formation is correlated with patient outcome, rather than providing mechanistic details about their anti- tumoral effects. The F99 phase of this proposal is focused on determining how T cell help varies and is distributed among different viral protein-specific B cell clones co-residing in GCs and TLSs using intercellular labeling and in vivo infection models. Having established novel methods to study immune networks in lymph nodes and virus- induced TLSs in lungs of Influenza A virus infected mice, I am characterizing the properties and directionality in which T cell help is provided to B cells of varying antigen-specificities and investigating how competition for T cell help shapes the antibody repertoire against Influenza A virus. For the K00 phase of this proposal, I plan to leverage my experiences using mechanistic mouse models of B- and T-cell collaboration with my prior work studying cancer immunology to elucidate the dynamics of TLS contribution to humoral immunity in vivo, with a focus on lung adenocarcinoma models. By characterizing the contacts between immune cells taking place in cancer-induced TLSs, I hope to uncover the pathways in tumor- bearing mice that generate beneficial TLSs. Applying my expertise with intercellular labeling approaches and tissue multi-photon microscopy, I aim to identify if and how the immune cell interaction landscape changes in the context of immunotherapy. These insights could then be used to develop ways to reprogram inert TLSs, or produce new TLSs, that are capable of tumor control.