Dissecting Disease Tolerance in Plasmodium vivax Malaria Using the Systemic Degree of Inflammatory Perturbation

Abstract Homeostatic perturbation caused by infection fosters two major defense stratagems, resistance and tolerance, which promote the host’s survival. Resistance relates to the ability of the host to restrict the pathogen load. Tolerance minimizes collateral tissue damage without directly affecting pathogen fitness. These concepts have been explored mechanistically in murine models of malaria but only superficially in human disease. Indeed, individuals infected with Plasmodium vivax may present with asymptomatic malaria, only mild symptoms, or be severely ill. We and others have reported a diverse repertoire of immunopathological events that potentially underly susceptibility to disease severity in vivax malaria. Nevertheless, the combined epidemiologic, clinical, parasitological, and immunologic features associated with defining the disease outcomes are still not fully understood. In the present study, we perform an extensive outlining of cytokines and inflammatory proteins in plasma samples from a cohort of individuals from the Brazilian Amazon infected with P. vivax and presenting with asymptomatic (n=108) or symptomatic (n=134) disease (106 with mild presentation and 28 with severe malaria), as well as from uninfected endemic controls (n=128) to elucidate these gaps further. We employ highly multidimensional Systems Immunology analyses using the molecular degree of perturbation to reveal nuances of a unique profile of systemic inflammation and imbalanced immune activation directly linked to disease severity as well as with other clinical and epidemiologic characteristics. The findings mapped the relationships between the systemic degree of inflammatory perturbation and parasitemia values to define the disease tolerance in vivax malaria. Author Summary Plasmodium vivax infection can result in a broad spectrum of disease manifestations, ranging from asymptomatic malaria to severe life-threatening disease. Despite significant advances in the current understanding of the critical factors associated with the disease outcomes in vivax malaria, the immunopathological events responsible for the diversity of severe manifestations in the disease remain deeply unknown. Here, a large panel of cytokines/chemokines were assessed in plasma samples from a Brazilian cohort of P. vivax patients presenting with asymptomatic infection or symptomatic malaria at the time of diagnosis, as well as from uninfected endemic controls, to define the relationships between systemic inflammation, disease presentation, parasitemia, and epidemiologic characteristics. In-depth analyses using the molecular degree of perturbation were employed to reveal nuances of a unique profile of systemic inflammation and imbalanced immune activation directly linked to disease severity. Moreover, the discoveries diagrammed the occurrence of disease tolerance by narrowing down the interactions between the systemic degree of inflammatory perturbation and parasitemia values in vivax malaria patients.