Eosinophils mediate SIgA production triggered by TLR2 and TLR4 to control Ascaris suum infection in mice

PLoS Pathog. 2021 Nov 16;17(11):e1010067. doi: 10.1371/journal.ppat.1010067. eCollection 2021 Nov.

Abstract

Human ascariasis is the most prevalent but neglected tropical disease in the world, affecting approximately 450 million people. The initial phase of Ascaris infection is marked by larval migration from the host's organs, causing mechanical injuries followed by an intense local inflammatory response, which is characterized mainly by neutrophil and eosinophil infiltration, especially in the lungs. During the pulmonary phase, the lesions induced by larval migration and excessive immune responses contribute to tissue remodeling marked by fibrosis and lung dysfunction. In this study, we investigated the relationship between SIgA levels and eosinophils. We found that TLR2 and TLR4 signaling induces eosinophils and promotes SIgA production during Ascaris suum infection. Therefore, control of parasite burden during the pulmonary phase of ascariasis involves eosinophil influx and subsequent promotion of SIgA levels. In addition, we also demonstrate that eosinophils also participate in the process of tissue remodeling after lung injury caused by larval migration, contributing to pulmonary fibrosis and dysfunction in re-infected mice. In conclusion, we postulate that eosinophils play a central role in mediating host innate and humoral immune responses by controlling parasite burden, tissue inflammation, and remodeling during Ascaris suum infection. Furthermore, we suggest that the use of probiotics can induce eosinophilia and SIgA production and contribute to controlling parasite burden and morbidity of helminthic diseases with pulmonary cycles.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Ascariasis / immunology*
  • Ascariasis / metabolism
  • Ascariasis / parasitology
  • Ascaris suum / immunology*
  • Eosinophils / physiology*
  • Female
  • Immunoglobulin A, Secretory / genetics
  • Immunoglobulin A, Secretory / metabolism*
  • Mice
  • Mice, Inbred BALB C
  • Mice, Inbred C57BL
  • Pneumonia / immunology
  • Pneumonia / parasitology
  • Pneumonia / prevention & control*
  • Toll-Like Receptor 2 / genetics
  • Toll-Like Receptor 2 / metabolism*
  • Toll-Like Receptor 4 / genetics
  • Toll-Like Receptor 4 / metabolism*

Substances

  • Immunoglobulin A, Secretory
  • Toll-Like Receptor 2
  • Toll-Like Receptor 4

Grants and funding

This work was funded by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) DSN was supported by a post-doctoral fellowship from CAPES (88887.335818/2019-00). This study was also financially supported by Fundação de Amparo a Pesquisa do Estado de Minas Gerais/FAPEMIG, Brazil (Grant no. CBB APQ-03280-15), the Brazilian National Research Council (CNPq) (Grant no. 303345/2018-7), and Pró-Reitoria de Pesquisa of Universidade Federal de Minas Gerais, to RTF. LLB, RCR, and RTF are Research Fellows (Bolsa de Produtividade em Pesquisa) from CNPq. The funders had no role in study design, data collection, and analysis, decision to publish, or preparation of the manuscript.