Enriched environment and stress exposure influence splenic B lymphocyte composition.

Area of Science:

• Immunology
• Stress Physiology
• Animal Models

Background:

• Prolonged chronic stress negatively impacts immune function and health.
• The spleen is a critical immune organ, but specific splenic lymphocyte responses to stress are not well understood.
• Understanding these responses is crucial for developing targeted interventions.

Purpose of the Study:

• To investigate the effects of chronic mild stress (CMS) on spleen composition in male mice.
• To compare these effects between standard caging and enriched environment (EE) housing conditions.
• To explore the relationship between stress hormones and splenic immune cell populations.

Main Methods:

• Male mice were exposed to unpredictable CMS under standard or EE conditions.
• Spleen cellularity, lymphocyte subsets (B and T cells), and B cell subtypes were analyzed.
• Fecal corticosterone metabolites (FCM) were measured to assess stress hormone levels.

Main Results:

• Enriched environment housing increased total splenocyte numbers.
• CMS reduced splenocyte numbers in both housing conditions.
• CMS altered the B:T lymphocyte ratio, increasing T cells and decreasing B cells in EE mice.
• CMS increased immature and marginal zone B cells while decreasing follicular B cells.
• Fecal corticosterone metabolites (FCM) were negatively correlated with splenocyte number and B:T ratio.

Conclusions:

• Spleen immune cell composition, particularly B lymphocytes, is modulated by housing environment and chronic stress.
• Enriched environments may alter the physiological response to stress, impacting splenic immune cell dynamics.
• These findings suggest differential immune priming based on environmental and stress exposures.