Metabolic regulation of anti-malarial humoral immunity

Abstract
Following infection, a subset of pathogen-specific B lymphocytes can rapidly differentiate into germinal center
(GC) B cells that undergo rapid proliferation and somatic hypermutation, resulting in the production of high-
affinity memory B cells (MBC) and long-lived antibody secreting plasma cells (LLPC). Studies of T lymphocytes
and cancer cells reveal that rapid differentiation and proliferation requires key changes in cellular metabolic
pathways. During malaria, B cell differentiation and function are suboptimal, leaving individuals in endemic areas
susceptible to repeated infection. Published work from our laboratory (Vijay et al. Nature Immunology. 2020)
showed that dysregulated glutamine metabolism is linked to energetic shortfalls that limit host protective humoral
immunity. In this project, the applicant will investigate how B lymphocytes utilize the amino acid glutamine and
its derivative glutamate to power proliferation, survival, and functional differentiation. The applicant’s new
preliminary data show that deletion of the mitochondrial glutamate transporter results in drastic reductions in the
number of GC B cells responding to Plasmodium infection, parasite-specific secreted antibody, and host
resistance to malaria. Despite these striking phenotypes, the specific cytosolic and mitochondrial metabolic
pathways fed by these metabolites are not known. It is also not known how these metabolites influence the
quantity and quality of GC-dependent MBC and LLPC populations. This project addresses these fundamental
knowledge gaps and will utilize in vivo and ex vivo experiments to define the intracellular biochemical dynamics
that govern the necessity of glutamine and glutamate, as well as the downstream effects that nutrient starvation
plays in how B cells respond to infection. The proposed research will reveal fundamental new information about
B cell metabolism, as well as identify the potential for metabolism-based therapeutic options relevant to
Plasmodium parasite infection. Aim 1 of this proposal will investigate how metabolite restriction in B cells impacts
their proliferation, survival, and functional differentiation by utilizing targeted temporal protein deletion mice and
analyzing readouts in blood parasite burden, immune cell expansion in spleen, and per-cell antibody production
potential. Aim 2 interrogates the specific biochemical pathways that are impacted by B cell nutrient starvation,
utilizing carbon tracing experiments in mice possessing targeted and B cell-restricted metabolite transporter
deletions. In addition to critical scientific advances in B cell metabolism, the successful completion of this project
will also immerse the applicant in a variety of cutting-edge research methods, gain experience in communication
and collaboration with both collaborators and non-scientific audiences, and will condition the applicant to be
better equipped his aspired career in academic scientific research.

Grant Number: 1F31AI194515-01
NIH Institute/Center: NIH
Principal Investigator: Jonathon Bernardi