# Role of mast cell-derived exosomes in exacerbating neuronal injury of experimental cerebral malaria

## TL;DR

Mast cell exosomes worsen brain damage in cerebral malaria by triggering stress in neurons.

## Contribution

This study identifies mast cell-derived exosomes as key drivers of neuronal injury in cerebral malaria through endoplasmic reticulum stress pathways.

## Key findings

- Exosomes from activated mast cells worsen survival and brain pathology in experimental cerebral malaria.
- Exosome treatment increases pro-inflammatory cytokines and ER stress markers in neurons.
- MicroRNA profiling reveals exosome-specific miRNA changes linked to neuronal stress pathways.

## Abstract

Cerebral malaria (CM), a fatal neurological complication of Plasmodium falciparum infection, is partially driven by neuronal injury. Emerging evidence highlights exosomes as vital mediators of mast cell–neuron interactions in neurological disease progression. While mast cells and their exosomes were previously shown to exacerbate experimental cerebral malaria (ECM) severity, the specific role of mast cell-derived exosomes in CM-associated neuronal injury remains unclear.

Exosomes were isolated from resting and lipopolysaccharide (LPS)-activated P815 mast cells (denoted as RE and AE, respectively) and characterized. These exosomes were administered to ECM mice and Plasmodium berghei ANKA (PbA)-infected red blood cell (iRBC)-stimulated neuronal HT-22 cells to investigate their functional impact and mechanisms.

Both RE and AE exhibited spherical morphology (20–100 nm diameter) and expressed exosomal markers (CD9, CD63, and CD81). Compared to infected controls, RE and AE treatments significantly reduced survival time, increased ECM incidence, and exacerbated brain pathology, blood–brain barrier disruption, neuronal injury, and apoptosis. Furthermore, RE and AE administration elevated messenger RNA (mRNA) levels of pro-inflammatory cytokines (interleukin [IL]-6, tumor necrosis factor alpha [TNF-α], and IL-1β) and increased numbers of neurons expressing endoplasmic reticulum (ER) stress markers (GRP78, CHOP, p-IRE1, XBP-1). Notably, AE treatment induced higher morbidity/mortality rates, more severe neuronal injury, and greater ER stress marker expression than RE. In vitro, RE-treated iRBC-stimulated neuronal HT-22 cells showed higher GRP78, CHOP, and XBP-1 mRNA levels than AE-treated cells. MicroRNA (miRNA) sequencing revealed three downregulated miRNAs (miR-330-3p, miR-185-5p, and miR-379-5p) and six upregulated miRNAs (miR-155-5p, miR-423-3p, miR-187-3p, miR-29c-3p, miR-188-5p, miR-192-5p) in AE versus RE, all previously implicated in targeting GRP78, CHOP, or XBP-1.

Mast cell-derived exosomes, particularly those from activated cells (AE), exacerbated ECM neuronal injury through partial activation of ER stress pathways.

The online version contains supplementary material available at 10.1186/s13071-025-06863-3.