Human neutrophil extracellular traps do not impair in vitro Toxoplasma gondii infection

A major Toxoplasma serine protease inhibitor protects the parasite against gut-derived serine proteases and NETosis damage

Toxoplasmosis is a life-threatening opportunistic infection in immunocompromised patients, caused by the parasite Toxoplasma gondii. Infection is initiated through oral ingestion of Toxoplasma cysts that must survive the harsh environment of the gut to undergo excystation. Released parasites invade intestinal epithelial cells and then disseminate throughout tissues for encystation, mainly in the brain. How Toxoplasma escapes destruction mediated by gastrointestinal proteases is poorly understood. T. gondii has nine genes encoding serine protease inhibitor proteins (TgPIs). TgPI-1 is highly expressed across all Toxoplasma strains and developmental stages and contains three domains for binding to various serine proteases. Here, we explore the role of TgPI-1 in protecting Toxoplasma against serine proteases in the gut and neutrophil-derived proteases in the lamina propria. TgPI-1 localizes to the parasite plasma membrane and cyst wall. We generated ΔTgPI-1 parasites, and the mutant is more sensitive to neutrophil elastase (NE), trypsin and chymotrypsin than WT. Neutrophils exposed to Toxoplasma release neutrophil extracellular traps (NET) with strain-dependent morphologies, ranging from spiky to extended cloudy. TgPI-1 was detected on NET containing NE, and ΔTgPI-1 parasites are more susceptible to destruction by NETosis. In mice, ΔTgPI-1 parasites exhibit reduced infectivity, poor dissemination to abdominal organs, and lower cyst burden in the brain. These findings shed light on a strategy employed by Toxoplasma to counteract enzymatic antimicrobial defenses in gut tissues, highlighting potential avenues for controlling tissue dissemination of this medically significant parasite.

Bibliometric analysis of neutrophil extracellular traps induced by protozoan and helminth parasites (2008-2024)

Introduction

Parasitic diseases pose a significant global public health challenge, affecting billions of people and causing substantial economic losses in livestock and poultry. In the fight against these infections, neutrophils play a crucial role, employing various strategies, including the release of neutrophil extracellular traps (NETs). Recent studies have made significant progress in understanding NETs triggered by protozoa and helminths. However, a comprehensive bibliometric analysis that compiles these findings and identifies research hotspots and trends in this field is still lacking.

Methods

We utilized the Web of Science Core Collection and Scopus databases to retrieve original articles on NETs induced by protozoa and helminths. After screening, the data was transferred to the visualization tools VOSviewer, Biblioshiny, and CiteSpace for analysis.

Results

Our study included 159 original articles published in 69 journals, involving 909 authors from 270 institutions across 41 countries. Germany and Brazil have made the most significant contributions to the research on NETs and parasites, accounting for 45 and 32 publications, and 1,495 and 1,342 citations, respectively. Carlos Hermosilla and Anja Taubert (Justus Liebig University Giessen, Germany), and Elvira Saraiva (Federal University of Rio de Janeiro, Brazil), are leaders in the field, both in terms of publication output and citations. Frontiers in Immunology has consistently and significantly impacted the field, and an article in the Proceedings of the National Academy of Sciences of the United States of America providing the first direct evidence of NETs release in response to a parasite is by far the most cited. Current research focuses on malaria, Toxoplasma gondii, Besnoitia besnoiti, nematodes, and the mechanisms of NETs production and their effects on parasites and host cells. Emerging trends include therapeutic targeting of NETs and comparative studies across different host and parasite species.

Conclusion

This study offers a comprehensive overview and visual analysis of NETs and parasites, highlighting key areas for future research.

Prevalence of coccidia in lagomorphs in China between 1981 and 2023: A systematic review and meta-analysis

Lagomorpha coccidiosis, caused by coccidia, is a prevalent disease affecting rabbits, hares and pikas. This meta-analysis aimed to estimate the pooled prevalence of coccidia infection in lagomorphs and identify potential risk factors. A systematic search of six databases yielded 102 studies published between 1981 and 2023. The pooled prevalence of Eimeriidae, Sarcocystidae and Cryptosporidiidae in lagomorphs was 76.4%, 6.2% and 3.9%, respectively. Rabbits had the highest prevalence of Eimeriidae (76.8%) and Sarcocystidae (7.4%), while pikas had the highest prevalence of Cryptosporidiidae (6.2%). Juvenile rabbits exhibited the highest prevalence of Eimeriidae (84.6%) and Cryptosporidiidae (9.9%). Northwest China had the highest prevalence of Eimeriidae (87.8%). Over time, the prevalence of Eimeriidae declined (Coefficient: -0.0062; P<0.05), but remained high (65.0%) in the past five years. Our findings highlight the prevalence of Eimeriidae infection in lagomorphs and the need for further research on Sarcocystidae and Cryptosporidiidae infections. We emphasize the importance of developing lagomorpha coccidia vaccines and implementing vaccination schedules for juvenile rabbits to mitigate coccidia infections.