Acute ischaemic stroke alters the composition and function of circulating B cells

Area of Science:

• Immunology
• Neuroscience
• Cell Biology

Background:

• Circulating B cells, including innate-like populations, play key roles in immunity.
• The impact of tissue injury, particularly acute ischaemic stroke (AIS), on B cell function is not well understood.
• AIS is a major cause of neurological disability and is linked to systemic immune dysfunction.

Purpose of the Study:

• To investigate the effects of AIS on circulating B cell populations and their functionality.
• To explore the role of neuroimmune factors in modulating B cell responses after stroke.
• To determine if stroke or secondary infections are the primary drivers of observed B cell alterations.

Main Methods:

• Analysis of circulating B cell populations in AIS patients and controls.
• Functional assays of B cells, including cytokine and immunoglobulin release.
• Investigation of B cell adrenergic receptor expression and response to noradrenaline (NA).
• In vitro experiments exposing healthy B cells to NA.

Main Results:

• AIS patients showed reduced numbers of marginal zone (MZ)-like B cells, an innate-like subset.
• B cells from AIS patients exhibited impaired release of Immunoglobulin M (IgM) and regulatory cytokines (IL-6, IL-10).
• B cells express adrenergic receptors, and in vitro exposure to NA mimicked some AIS-related functional changes, including increased MZ-like B cell death.
• Observed B cell alterations were primarily attributed to the stroke itself, not secondary infections.

Conclusions:

• Acute ischaemic stroke rapidly modifies circulating B cell populations and their function.
• Neuroimmune signaling, particularly via noradrenaline, significantly impacts B cell responses post-stroke.
• Altered innate-like B cell function is a previously unrecognized feature of the systemic immune response to AIS.