Hunger Hormone Receptor Emerges as Unexpected Lever Against Parasitic Liver Disease

A hormone best known for making us feel hungry has turned out to be a surprising accomplice of one of the world’s most stubborn parasitic diseases. In a study published in Acta Parasitologica, researchers in Xinjiang, China, report that blocking the receptor for ghrelin—the so-called hunger hormone—significantly slows the progression of cystic echinococcosis in the liver, a debilitating infection caused by the larval stage of the tapeworm Echinococcus granulosus. The findings, based on ninety days of controlled treatment in infected mice, suggest that a signaling pathway long studied in metabolism and appetite regulation could become an unexpected target for a disease that currently offers few effective drug options.

Cystic echinococcosis is a zoonotic parasitic disease in which humans inadvertently become intermediate hosts of E. granulosus. After ingestion of parasite eggs, larvae migrate chiefly to the liver, where they develop into fluid-filled hydatid cysts that expand slowly over years. The disease is characterized by hepatic fibrosis and liver necrosis, and in endemic regions spanning Central Asia, the Middle East, South America and parts of China, it imposes a heavy burden of chronic illness. Surgery remains the definitive treatment for many patients, but drug therapy relies on a small arsenal of benzimidazole compounds that often achieve only parasitostatic rather than parasiticidal effects. The search for new molecular targets has therefore become a priority for parasitologists.

Ghrelin, an acylated peptide hormone discovered in 1999, is produced mainly by the stomach and acts through its receptor GHSR, a G protein-coupled receptor distributed throughout the central nervous system and peripheral tissues. Beyond stimulating appetite and growth hormone release, ghrelin has been implicated in inflammation, cell proliferation and fibrogenesis in the liver. Previous work by some of the same investigators had shown that ghrelin and GHSR regulate the progression of hepatic E. granulosus infection, and that genetic knockout of the GHSR gene inhibits disease progression in mice. What remained unclear was the precise mechanism by which this receptor influences the host–parasite battleground, and whether pharmacological blockade could reproduce the protective effect seen in knockout animals.

To answer these questions, the team led by Guangfeng Chen and Jiang Zhu infected mice experimentally with E. granulosus and then treated them for ninety days with either recombinant ghrelin protein or [D-Lys3]-GHRP-6, a well-characterized GHSR antagonist, delivered by intraperitoneal injection. The researchers then measured a battery of molecular and pathological indicators, including serum hormone levels, hepatic and lesion-perilesional gene and protein expression, proliferation markers, and fibrotic pathway activity. The long treatment window was designed to capture the chronic nature of hydatid disease, which unfolds over months rather than days in the natural host.

The results were strikingly bidirectional. In mice that received ghrelin, serum ghrelin concentrations rose and ghrelin/GHSR expression increased in both liver tissue and the tissue surrounding the parasitic lesions. These animals showed elevated levels of classic cell proliferation markers—Ki67, PCNA, Cyclin D1 and Cyclin E1—indicating heightened hepatocellular division. At the same time, ghrelin suppressed the hepatic TGF-β1/Smad3 fibrotic signaling pathway and reduced the abundance of fibrosis-associated proteins including alpha-smooth muscle actin, Collagen I and Collagen III. The net effect was deleterious for the host: ghrelin treatment promoted the progression of hepatic E. granulosus infection, effectively giving the parasite more room and resources to expand.

The antagonist told the opposite story. When infected mice were given [D-Lys3]-GHRP-6, serum ghrelin fell and hepatic ghrelin/GHSR levels declined. Expression of the cell proliferation-related proteins dropped, while the TGF-β1/Smad3 fibrotic pathway was activated and fibrotic protein expression increased. Pathologically, this shift translated into a denser fibrotic capsule forming around the parasite and a measurable alleviation of infection progression. In other words, shutting down the ghrelin signal encouraged the liver to wall off the parasite behind scar tissue rather than nurturing it with proliferating host cells.

The mechanistic logic of this finding reframes fibrosis in an unexpected light. In most liver diseases, fibrosis is the villain—a runaway wound-healing response that culminates in cirrhosis and organ failure. But in the context of a parasitic cyst, the fibrotic capsule is a defensive structure, a biological containment wall that restricts the parasite’s access to nutrients and space. By suppressing the TGF-β1/Smad3 axis, ghrelin appears to soften this wall and simultaneously drive the proliferation of host cells that the growing cyst can exploit. Blocking GHSR reverses both effects at once, tightening the enclosure and starving the lesion of proliferative support.

The study builds on a coherent line of earlier evidence. Research in rodents has shown that ghrelin can attenuate hepatocellular injury and liver fibrogenesis in toxic and cirrhotic models, and subsequent work linked ghrelin signaling to TGF-β1 regulation and autophagy in fibrotic livers. Within echinococcosis research specifically, the group had previously reported that ghrelin modulates immunoinflammation and fibrosis in infected liver lesions, and that GHSR gene knockout reduces parasite survival and alleviates the pathological liver response. The new pharmacological data close an important gap by demonstrating that a receptor antagonist—a class of molecules that can, in principle, be developed into drugs—achieves the same protective phenotype as genetic deletion.

Several caveats temper the enthusiasm. The experiments were conducted in mice over a defined ninety-day window, and cystic echinococcosis in humans develops over years within a more complex immune environment. [D-Lys3]-GHRP-6 is a research tool rather than a clinical compound, and chronic GHSR blockade would need to be weighed against ghrelin’s physiological roles in appetite, growth hormone secretion, cardiovascular function and energy homeostasis. Safety, dosing, delivery and efficacy in large animal models of hydatid disease all remain to be established before any translational pathway can be contemplated. The authors also note that the raw data underlying the study are available from the corresponding author upon reasonable request, and the work was approved by the institutional animal ethics committee.

Even so, the study adds a genuinely novel dimension to echinococcosis research by connecting neuroendocrine metabolism to parasite containment. If the mechanism holds in further models, GHSR antagonists—or upstream regulators of the ghrelin system such as the antagonist peptide LEAP-2—could inspire a new class of host-directed therapies for cystic echinococcosis, complementing or even replacing direct antiparasitic drugs that the parasite has limited susceptibility to. For a disease that the World Health Organization has listed among the neglected tropical diseases, and for which current pharmacotherapy falls short in many patients, the idea that a hunger hormone receptor could help the liver imprison its invader is the kind of counterintuitive insight from which new treatments are often born.

Subject of Research: Role of ghrelin receptor signaling in hepatic Echinococcus granulosus infection and liver fibrosis

Article Title: Ghrelin Receptor Blockade Restricts Hepatic Echinococcus granulosus Infection by Suppressing Host Cell Proliferation and Enhancing Fibrotic Encapsulation

Article References: Chen, G., Dilixiati, B., Zhou, T., Rao, X., Aimidoula, R., Zhang, W., Zhao, H., Wusiman, A., & Zhu, J. (2026). Ghrelin Receptor Blockade Restricts Hepatic Echinococcus granulosus Infection by Suppressing Host Cell Proliferation and Enhancing Fibrotic Encapsulation. Acta Parasitologica, 71(5), Article 225. https://doi.org/10.1007/s11686-026-01407-w

Image Credits: AI Generated

DOI: 10.1007/s11686-026-01407-w

Keywords: cystic echinococcosis, Echinococcus granulosus, ghrelin, GHSR, liver fibrosis, TGF-beta/Smad3, cell proliferation, parasitology, hydatid disease, G protein-coupled receptor, host-directed therapy, fibrotic encapsulation