Peyer’s Patch B Cells Drive Celiac Disease Autoimmunity

Yes, Peyer’s patch B cells play a critical role in driving celiac disease autoimmunity. Here is a detailed explanation based on the context provided:

1. Role of Peyer’s Patches in Celiac Disease:

• Peyer’s patches are specialized lymphoid tissues located in the small intestine, acting as primary inductive sites for intestinal immune responses.
• In celiac disease, Peyer’s patches are pivotal in initiating and sustaining the autoimmune response, particularly the production of disease-specific antibodies.

2. TG2-Specific B Cells in Peyer’s Patches:

• TG2-specific B cells, which recognize and bind to transglutaminase 2 (TG2), are found in Peyer’s patches and gut-draining mesenteric lymph nodes.
• These B cells are not tolerized (i.e., they are not rendered inactive or deleted), which allows them to contribute to the autoimmune process in celiac disease.

3. Central T–B Cell Crosstalk:

• The pathogenesis of celiac disease depends on the interaction between gluten-specific CD4⁺ T cells and TG2-specific B cells.
• TG2-specific B cells present gluten peptides to gluten-specific T cells, receiving help in the form of activation signals. This T–B cell cooperation is essential for the production of anti-TG2 autoantibodies.

4. Antigen Sampling and Uptake:

• TG2-specific B cells in Peyer’s patches localize in the subepithelial dome (SED), where they directly sample antigens (gluten and TG2) from the gut lumen.
• These B cells use their B-cell receptor (BCR) to take up TG2 directly, but this uptake is highly specific—it requires catalytically active TG2 and a matching TG2-specific BCR.

5. Amplification of Autoimmune Responses:

• Increased levels of luminal TG2, potentially due to conditions like infections or heightened epithelial turnover, may amplify gluten-specific T-cell responses during active disease.
• This amplification mechanism highlights the significance of Peyer’s patch B cells in perpetuating the immune response in celiac disease.

6. Germinal Center and Extrafollicular Phenotypes:

• Activated TG2-specific B cells in Peyer’s patches display germinal center and extrafollicular phenotypes, indicating their involvement in both long-term antibody production and rapid immune responses.

7. Therapeutic Implications:

• Given the central role of TG2-specific B cells in Peyer’s patches, targeting these cells or blocking TG2 activity could serve as a potential therapeutic strategy for celiac disease.
• Approaches such as inhibiting TG2 enzymatic activity, disrupting T–B cell interactions, or depleting autoreactive B cells are being explored as treatments.

Conclusion:

Peyer’s patch B cells are key drivers of celiac disease autoimmunity through their ability to recognize TG2, interact with gluten-specific T cells, and produce disease-specific autoantibodies. These findings underscore the importance of Peyer’s patches as critical sites for the initiation and propagation of the autoimmune response in celiac disease.