Lactobacillus casei reduces CD8+ T cell-mediated skin inflammation

Area of Science:

• Immunology
• Microbiology
• Dermatology

Background:

• Probiotics, particularly Lactobacilli, are suggested to help with allergic and inflammatory conditions.
• However, scientific evidence demonstrating their anti-inflammatory effects through immune modulation of T cells is limited.

Purpose of the Study:

• To investigate if Lactobacillus casei (L. casei) influences antigen-specific T cell-mediated skin inflammation.
• To explore the role of L. casei in allergic contact dermatitis models.

Main Methods:

• Contact hypersensitivity (CHS) model using 2,4-dinitrofluorobenzene was employed.
• Mice were orally administered fermented milk with L. casei or L. casei alone.
• The study analyzed the impact on CD8+ cytotoxic T lymphocytes (CTL) and CD4+ regulatory T cells.

Main Results:

• Daily oral administration of L. casei significantly decreased skin inflammation.
• This reduction was achieved by inhibiting the priming and expansion of hapten-specific IFN-gamma-producing CD8+ effector T cells.
• The anti-inflammatory effect was dependent on CD4+ T cells, which regulate the CD8+ T cell pool size.

Conclusions:

• This research provides the first evidence that oral L. casei administration can mitigate antigen-specific skin inflammation.
• L. casei modulates the immune response by controlling the CD8+ effector T cell population.
• Components of the L. casei cell wall appear to contribute to its immunomodulatory effects.