Intensive fish farming raises the incidence of injuries and diseases. Skin mucus acts as a mechanical, physical, chemical, biological, and immunological barrier against any external stressor. Skin mucus has become a novel area of research and a true indicator of the immune status of fish. The skin mucus proteome has recently been studied in several fish species. Furthermore, the modulation of the skin mucus proteome has been investigated in response to infection, wounds, stress, or after administration of different dietary supplements . Wound healing and tissue repair are highly complex and indispensable processes to ensure the survival and health of an organism. The regenerative competence differs considerably across organs and organisms and requires the harmonized inter action of different cell types and signaling systems
Ichthyophthirius multifiliis is a ciliated protozoan parasite recognized as one of the most pathogenic diseases of wild and cultured freshwater fish. Fish skin mucus plays a significant role against invading pathogens. However, the protein-based modulation against infection with I. multifiliis , of host fish at this barrier is unknown . Thus, we investigated the skin mucus proteome of common carp using a shotgun proteomic approach at days 1 and 9 after I. multifiliis exposure.
We hypothesized that a proteomic evaluation of skin mucus from non-exposed fish against those exposed to I. multifiliis would facilitate the identification of specific mucus components that are involved in carp immune response to tissue damage caused by the parasite.
The aim of this study was to investigate the modulation of the skin mucus after infection with I. multifiliis using quantitative proteomics to provide insights into the post-transcriptional and post-translational regulation of skin mucus proteins.
We identified 25 differentially expressed proteins in infected carp skin mucus. Upregulated proteins were mainly involved in metabolism, whereas downregulated proteins were mainly structural.
This is the first proteomic analysis of infected common carp skin mucus, and it provides novel information about proteome alteration caused by I. multifiliis .
Furthermore, we identified novel proteins with yet unknown function in common carp following penetrating injuries such as olfactomedin 4, lumican , dermatopontin, papilin and and I cytoskeletal 18 .
This analysis, therefore, represents a key for the search for potential biomarkers, which can help in a better understanding and monitoring of interactions between carp and I. multifiliis .
This proteomic study not only provides information on the protein-level pathways involved in fish-ciliate interactions but also could represent a complementary system for studying tissue repair.