The Interface Between Inflammatory Mediators and MicroRNAs in Plasmodium vivax Severe Thrombocytopenia.

Marina L S Santos,Laurence R Amaral,Luiz F F Guimarães,Matheus S Gomes,Luzia H Carvalho,Ibrahim Hawwari,Dhelio B Pereira,Roney S Coimbra,Tais N Sousa,Bernardo S Franklin,Cor J F Fontes

doi:10.3389/fcimb.2021.631333

Abstract

Severe thrombocytopenia can be a determinant factor in the morbidity of Plasmodium vivax, the most widespread human malaria parasite. Although immune mechanisms may drive P. vivax-induced severe thrombocytopenia (PvST), the current data on the cytokine landscape in PvST is scarce and often conflicting. Here, we hypothesized that the analysis of the bidirectional circuit of inflammatory mediators and their regulatory miRNAs would lead to a better understanding of the mechanisms underlying PvST. For that, we combined Luminex proteomics, NanoString miRNA quantification, and machine learning to evaluate an extensive array of plasma mediators in uncomplicated P. vivax patients with different degrees of thrombocytopenia. Unsupervised clustering analysis identified a set of PvST-linked inflammatory (CXCL10, CCL4, and IL-18) and regulatory (IL-10, IL-1Ra, HGF) mediators. Among the mediators associated with PvST, IL-6 and IL-8 were critical to discriminate P. vivax subgroups, while CCL2 and IFN-γ from healthy controls. Supervised machine learning spotlighted IL-10 in P. vivax-mediated thrombocytopenia and provided evidence for a potential signaling route involving IL-8 and HGF. Finally, we identified a set of miRNAs capable of modulating these signaling pathways. In conclusion, the results place IL-10 and IL-8/HGF in the center of PvST and propose investigating these signaling pathways across the spectrum of malaria infections.

Highlights

Plasmodium vivax is the most widespread human malaria parasite, placing 3.3 billion people at risk worldwide (Battle et al, 2019)
From all the cytokines that showed correlations with platelet counts (Figure 1 and Figure S3B), this analysis highlighted eight proteins (CXCL10, CCL2, CCL4, IL-10, Interleukin 1 Receptor Antagonist (IL-1Ra), Interferon gamma (IFN-g), IL-18, and Hepatocyte Growth Factor (HGF)) as part of a specific pattern linked to P. vivax-induced severe thrombocytopenia (PvST), as compared to unexposed healthy controls (Figure 2A)
The ensemble of inflammatory mediators differentially expressed in the subgroups of P.vivax patients and healthy controls essentially selected a mixed panel of mediators abovementioned as linked to PvST (Figure S4A); hierarchical clustering analysis did not yield in a specific pattern to differentiate moderate thrombocytopenia from other groups (Figure S4B)

Summary

Introduction

Plasmodium vivax is the most widespread human malaria parasite, placing 3.3 billion people at risk worldwide (Battle et al, 2019). In non-immune humans, P. vivax causes a broad spectrum of clinical symptoms, ranging from asymptomatic parasitemia and prodromal symptoms followed by uncomplicated fever to multiple life-threatening organ failure (Bassat and Alonso, 2011). P. vivax has a lower pyrogenic threshold (the parasite density required to evoke a fever), and common prodromal symptoms include headache, anorexia, malaise, myalgias and/or gastrointestinal symptoms for one or more days, sometimes with periodicity (Anstey et al, 2012). It is currently a consensus that the virulence of P. vivax has been underestimated (Tjitra et al, 2008; Lacerda et al, 2012; Douglas et al, 2014), in the presence of co-morbidities (Anstey et al, 2012). Findings suggest that tissue accumulation of P. vivax may occur, with the hidden biomass greatest in severe disease and capable of mediating systemic inflammation (Barber et al, 2015; Silva-Filho et al, 2020)

Methods

Results

Conclusion