Controlled human malaria infection leads to long-lasting changes in innate and innate-like lymphocyte populations

M Mpina, NJ Maurice, M Yajima, CK Slichter… - The Journal of …, 2017 - journals.aai.org
M Mpina, NJ Maurice, M Yajima, CK Slichter, HW Miller, M Dutta, MJ McElrath, KD Stuart…
The Journal of Immunology, 2017journals.aai.org
Animal model studies highlight the role of innate-like lymphocyte populations in the early
inflammatory response and subsequent parasite control following Plasmodium infection. IFN-
γ production by these lymphocytes likely plays a key role in the early control of the parasite
and disease severity. Analyzing human innate-like T cell and NK cell responses following
infection with Plasmodium has been challenging because the early stages of infection are
clinically silent. To overcome this limitation, we examined blood samples from a controlled …
Animal model studies highlight the role of innate-like lymphocyte populations in the early inflammatory response and subsequent parasite control following Plasmodium infection. IFN-γ production by these lymphocytes likely plays a key role in the early control of the parasite and disease severity. Analyzing human innate-like T cell and NK cell responses following infection with Plasmodium has been challenging because the early stages of infection are clinically silent. To overcome this limitation, we examined blood samples from a controlled human malaria infection (CHMI) study in a Tanzanian cohort, in which volunteers underwent CHMI with a low or high dose of Plasmodium falciparum sporozoites. The CHMI differentially affected NK, NKT (invariant NKT), and mucosal-associated invariant T cell populations in a dose-dependent manner, resulting in an altered composition of this innate-like lymphocyte compartment. Although these innate-like responses are typically thought of as short-lived, we found that changes persisted for months after the infection was cleared, leading to significantly increased frequencies of mucosal-associated invariant T cells 6 mo postinfection. We used single-cell RNA sequencing and TCR αβ-chain usage analysis to define potential mechanisms for this expansion. These single-cell data suggest that this increase was mediated by homeostatic expansion-like mechanisms. Together, these data demonstrate that CHMI leads to previously unappreciated long-lasting alterations in the human innate-like lymphocyte compartment. We discuss the consequences of these changes for recurrent parasite infection and infection-associated pathologies and highlight the importance of considering host immunity and infection history for vaccine design.
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