Tapeworm Protein Dampens Immune Alarm to Limit Heart Reperfusion Injury in Mice

In a mouse model, a single intraperitoneal dose of recombinant antigen B subunit 2 (rEgAgB8/2), given at the moment coronary blood flow was restored, improved cardiac function, reduced infarct size, and lowered blood levels of enzymes released by dying heart muscle. The findings, published as an open-access research article in Parasites & Vectors, describe an immunological route by which this parasite-derived molecule tempered the inflammation that injures heart tissue during reperfusion. The researchers ligated the left anterior descending coronary artery in mice for one hour and then allowed twenty-four hours of reperfusion, reproducing the clinical sequence of heart attack followed by revascularization. rEgAgB8/2 is a recombinant version of subunit 2 of antigen B, a protein of the E. granulosus cyst fluid that is known to modulate the host immune response.

Twenty-four hours after reperfusion began, the treated mice fared measurably better than untreated controls. Echocardiography showed improved cardiac function, and TTC/Evans Blue staining revealed smaller infarcts. Levels of lactate dehydrogenase and creatine kinase-MB were significantly reduced in the blood of treated animals, and histopathological analysis of the heart tissue corroborated the functional and biochemical signs of protection.

The immunological signature of the treated hearts shifted consistently. Pro-inflammatory cytokines TNF-α, IL-6, and IL-1β dropped in both serum and cardiac tissue, while the anti-inflammatory cytokines IL-10 and TGF-β rose. The inflammatory M1 macrophage marker iNOS was downregulated in cardiac tissue, whereas the M2 marker Arg-1 was upregulated, indicating a shift in macrophage polarization toward the repair-associated M2 phenotype in the injured myocardium.

To probe the mechanism, the team turned to bone marrow-derived macrophages grown in culture. When exposed to rEgAgB8/2, the cells secreted a cytokine profile matching the in vivo observations and showed reduced activation of the cGAS–STING pathway, an intracellular sensor system that signals through the proteins TBK1 and IRF3 to drive inflammatory responses. Flow cytometry identified M1 cells by the surface marker CD86 and M2 cells by CD206, and the treated macrophages showed enhanced polarization toward the M2 phenotype.

Western blotting of both myocardial tissue and cultured macrophages demonstrated lower levels of proteins in the cGAS/STING/p-TBK1/p-IRF3 signaling pathway after treatment, linking the parasite protein's effect directly to this innate immune signaling axis in the same animals and cells where protection and polarization were measured. The authors conclude that rEgAgB8/2 promotes macrophage polarization toward the M2 phenotype in a manner associated with suppression of the cGAS/STING/TBK1/IRF3 pathway, thereby attenuating myocardial ischemia–reperfusion injury and the associated inflammation. They frame the result as a potential novel therapeutic strategy for reperfusion injury and related inflammatory diseases.

Important caveats remain. The work was conducted in mice with a single twenty-four-hour reperfusion timepoint, and the protein was delivered intraperitoneally. Within this short-term model the study shows that pathway suppression, macrophage polarization, and tissue protection occurred together, and the shared version of the article is an accepted manuscript subject to further editorial processing.

The findings are preclinical and do not yet establish any benefit for human patients.

Subject of Research: Recombinant Echinococcus granulosus antigen B8/2 modulation of the macrophage cGAS–STING pathway in mouse myocardial ischemia–reperfusion injury

Article Title: Echinococcus granulosus antigen B regulates the macrophage cGAS–STING pathway to mitigate myocardial ischemia–reperfusion injury

Article References: Wang, S., Chen, F., Luo, Y., Jin, Q., Li, H., Li, H., Yang, C., Li, X., Wang, W., Gao, E., Chu, L., Qiu, Y., Zhou, R., & Yang, X. (2026). Echinococcus granulosus antigen B regulates the macrophage cGAS–STING pathway to mitigate myocardial ischemia–reperfusion injury. Parasites & Vectors. https://doi.org/10.1186/s13071-026-07653-1

Image Credits: AI Generated

DOI: 10.1186/s13071-026-07653-1

Keywords: Echinococcus granulosus, antigen B, cGAS-STING, macrophage polarization, M2 macrophages, myocardial ischemia-reperfusion injury, inflammation, cytokines, preclinical study, immunomodulation, Echinococcus, granulosus