A major ecological niche of eosinophils in evolving Schistosoma granulomas challenges the eosinophil view as “helminth killer” cells
- Luccas M. Barata
- Kássia K. Malta
- Vitor H. Neves
- Cinthia Palazzi
- Eliane G. Oliveira-Barros
- Yasmin Aguiar
- Felipe Kneip
- Bruno A. Marcelino
- Lívia A. S. Carmo
- João Felipe Audi-Gazeta
- Pedro H. S. Santos
- Maria Karolynna B. Milani
- Michelle C. A. Paula
- Eliana C. B. Toscano
- Rosana Gentile
- Felipe F. Dias
- Thiago P. Silva
- Rossana C. N. Melo
2025-06-11
Eosinophil-rich granulomas, formed around tissue-trapped parasite eggs, are hallmarks of schistosomiasis mansoni, a prevalent neglected tropical disease. How eosinophils populate and affect the complex Schistosoma granulomas remains unclear. Here, we mapped eosinophils across evolutional hepatic granulomas in a mouse model and in a primary wild reservoir for human schistosomiasis in Brazil (water rat Nectomys squamipes ). With in-depth quantitative image analysis and three-dimensional histological reconstructions of entire granulomas, we find that eosinophils are spatially organized and occupy a major, peripheral niche conserved across space and time in all granuloma stages and both experimental and natural infections. Within this niche, immature and mature eosinophils coinhabit, compartmentalize their major basic protein-1 content, robustly interact with other immune cells, and secrete through piecemeal degranulation. This unveiled niche, unrelated to parasite eggs, challenges the concept of eosinophil as a “helminth killer” cell and invigorates its view as an immunoregulatory cell of the tissue microenvironment in Schistosoma granulomas.