Atlas of grass carp (Ctenopharyngodon idella) in single cells Peripheral blood IgM+ B cells shed light on teleost fish immunological responses mediated by B cells.

• A Parimalagantham

  English

  Author

It is yet unknown how their immune systems react
to bacterial infections. The transcriptome
landscape of peripheral blood IgM+ B cells in
grass carp (Ctenopharyngodon idella) was
characterized in the current study using 10×
Genomics single-cell RNA sequencing (scRNA-
seq) after the fish were challenged with
Aeromonas hydrophila, a significant aquatic
pathogen. (im)mature B cells, innate B cells,
proliferative B cells, IgDhigh B cells, and two
infection-induced subsets known as infection Ⅰ
and Ⅱ B cells are among the six transcriptionally
different IgM+ B cell subpopulations that were
found. Bacterial infection increased the
immunological activation of circulating B cells,
changed the cellular heterogeneity of IgM+ B
cells, and caused metabolic reprogramming in
(im)mature and innate B cell subpopulations.
Interestingly, after being exposed to A. hydrophila,
infection-induced B cells showed strong
production of interferon φ1 (IFNφ1), a type I IFN.
Teleost B cells actively contribute to innate
antibacterial responses through IFN signaling, as
demonstrated by the further validation of this
induction through in vitro bacterial stimulation.
Furthermore, peripheral blood persistently
included the IgDhigh B cell subpopulation in both
infected and uninfected conditions, suggesting a
constitutive and probably mature phenotype.
These discoveries greatly expand our knowledge
of peripheral blood IgM+ B cell heterogeneity and
offer fresh perspectives on IgM+ B cell-
teleost fish immunological responses that are
mediated.

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