2023-08-24 17:45:43
Mussels release immune cells outside of their bodies in response to injury and infection.
This has been confirmed in a study led by the Higher Council for Scientific Research (CSIC), through the Immunology and Genomics group of the Marine Research Institute (IIM).
The authors of the study have observed that the mollusk releases immune cells into the space between the shells. Therefore, these free hemocytes could constitute the first line of defense and extend the immune alert system outside the mussel’s body.
“The mussel, a mollusc of which Spain is the third largest producer in the world, is characterized, among other aspects, by being highly resistant to pathogens. And, as is the case with all invertebrates, it depends solely on its innate immunity, in which hemocytes play the main role”, explains Antonio Figueras, CSIC research professor at the IIM. “It is known that the main player in the mussel’s immune system is the blood cells or hemocytes, and various studies have been carried out on the hemocytes that are inside the body of the bivalve. However, to date, none had been developed in depth on its presence in the intervalval fluid, which is essentially seawater”, adds the scientist.
In the research group, which has been dedicated to the study of the mussel immune response for more than 40 years, the chance observation of cells similar to hemocytes in the interval space (delimited by the shells, surrounded by the mantle and where they are the gills), where supposedly there is only seawater, led them to study these cells in greater depth and to compare them with the hemocytes that can be found inside the mussel’s body.
To do this, they designed a study with the objective of analyzing the characteristics of the hemocytes in the intervalval fluid of the mussels and their response to different stimuli (tissue injury and a bacterial infection transmitted by water) in comparison with the hemocytes of the hemolymph. , your circulatory fluid. They analyzed and compared the number, size, movement, production of reactive oxygen species, phagocytosis, and expression of genes related to migration and immune functions of hemocytes outside (intervalvar fluid) and inside the mussel body.
Mussels, along with some sea urchins. (Photo: NOAA OKEANOS EXPLORER Program, Gulf of Mexico 2014 Expedition)
The results obtained by the research team reveal that the hemocytes of the mussel intervalval fluid share common characteristics with those of the hemolymph, such as cell morphology or the structure of the cell population. However, they also show significant differences in size (smaller in the intervalval fluid), motility (commonly faster in the intervalval fluid), as well as in the production of substances to attack microorganisms or in the expression of immune genes that are overexpressed. in intervalval fluid cells compared to hemolymph cells.
“In conclusion, although most of the studies in mussels are carried out with hemolymph extracted from the posterior adductor muscle, the population of hemocytes in the intervalval fluid should be studied further, especially when the mussels are in stressful situations”, they advance from the team of investigation.
The study is titled “Mytilus galloprovincialis releases immunologically functional haemocytes to the intervalvar space in response to tissue injury and infection”. And it has been published in the academic journal Fish and Shellfish Immunology. (Source: Ana Bellón / CSIC)
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