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Global amphibian declines are compounded by deadly disease outbreaks caused by the chytrid fungus,Batrachochytrium dendrobatidis(Bd). Much has been learned about the roles of amphibian skin-produced antimicrobial components and microbiomes in controllingBd, yet almost nothing is known about the roles of skin-resident immune cells in anti-Bddefenses. Mammalian mast cells reside within and serve as key immune sentinels in barrier tissues like skin. Accordingly, we investigated the roles ofXenopus laevisfrog mast cells duringBdinfections. Our findings indicate that enrichment ofX. laevisskin mast cells confers anti-Bdprotection and ameliorates the inflammation-associated skin damage caused byBdinfection. This includes a significant reduction in infiltration ofBd-infected skin by neutrophils, promoting mucin content within cutaneous mucus glands, and preventingBd-mediated changes to skin microbiomes. Mammalian mast cells are known for their production of the pleiotropic interleukin-4 (IL4) cytokine and our findings suggest that theX. laevisIL4 plays a key role in manifesting the effects seen following cutaneous mast cell enrichment. Together, this work underscores the importance of amphibian skin-resident immune cells in anti-Bddefenses and illuminates a novel avenue for investigating amphibian host–chytrid pathogen interactions.
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This content will become publicly available on January 1, 2027
Investigating the potential neurotoxic effects of cell-free factors by Batrachochytrium dendrobatidis on locomotion in Xenopus laevis
ABSTRACT Chytridiomycosis is a contributor to amphibian population declines. Diseased amphibians show symptoms of lethargy and loss of righting reflexes, likely due to an ion imbalance across the skin. However, it is possible developing zoosporangia release toxins that affect neuromuscular activity. Using Xenopus laevis as a model, we hypothesized that locomotor performance would be affected by injection of Bd supernatant factors. X. laevis were injected and then filmed performing a swimming escape response with high-speed cameras at 4 h, 24 h, and 1-week post-injection. Average maximum swimming velocity and escape latency were digitized using high-speed video. Despite no difference in escape velocity, there was a significant difference in escape latency 24 h post injection at both concentrations tested, 106 and 107 cell equivalents, though only differences at 106 cell equivalents/ml supernatant persisted 1 week post injection. Changes in specific locomotor function suggest that there may be neurotoxins present, though the potential neurotoxins may exhibit neural circuit specificity across escape behavior. This study provides a method to test more purified extracts to determine whether Bd produces neurotoxic factors that could enter the blood stream and alter locomotion during a natural skin infection.
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- PAR ID:
- 10708535
- Publisher / Repository:
- The Company of Biologists
- Date Published:
- Journal Name:
- Biology Open
- Volume:
- 15
- Issue:
- 1
- ISSN:
- 2046-6390
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Global amphibian declines are largely driven by deadly disease outbreaks caused by the chytrid fungus, Batrachochytrium dendrobatidis (Bd). In the time since these disease outbreaks were first discovered, much has been learned about the roles of amphibian skin-produced antimicrobial components and skin microbiomes in controlling Bd. Yet almost nothing is known about the roles of skin-resident immune cells in anti-Bd defenses. Notably, mammalian mast cells reside within and serve as key immune sentinels in barrier tissues like the skin. Thus, they are critical to immune recognition of pathogens and to orchestrating the ensuing immune responses. Accordingly, we investigated the roles of Xenopus laevis frog mast cells during Bd infections. Our findings indicate that enrichment of X. laevis skin mast cells confers significant anti-Bd protection and ameliorates the inflammation-associated skin damage caused by Bd infection. Moreover, enriching X. laevis mast cells promotes greater mucin content within cutaneous mucus glands and protects frogs from Bd-mediated changes to their skin microbiomes. Together, this work underlines the importance of amphibian skin-resident immune cells in anti-Bd defenses and introduces a novel approach for investigating amphibian host-chytrid pathogen interactions.more » « less
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