Intratumoral B cells under stress

Area of Science:

• Immunology
• Cancer Biology
• Microbiome Research

Background:

• Stress hormones like corticosterone can impact immune function.
• Germinal center B cell responses are crucial for effective anti-tumor immunity.
• The interplay between gut microbiota and cancer-associated fibroblasts (CAFs) in immune suppression is not fully understood.

Purpose of the Study:

• To investigate how stress-induced corticosterone affects germinal center B cell responses and anti-tumor immunity.
• To identify the specific triggers and mechanisms by which corticosterone is secreted in the tumor microenvironment.
• To elucidate the role of gut microbiota in activating immune-suppressive pathways.

Main Methods:

• Analysis of B cell responses in the presence of corticosterone.
• Investigating Toll-like receptor 9 (TLR9) activation by microbial DNA.
• Assessing corticosterone secretion by cancer-associated fibroblasts (CAFs).
• Utilizing mouse models to study gut microbiota-derived signals.

Main Results:

• Stress-induced corticosterone was found to suppress germinal center B cell responses.
• Impaired anti-tumor immunity was observed due to corticosterone.
• Gut microbiota-derived phage DNA was identified as a trigger for TLR9 activation.
• CAFs were shown to secrete corticosterone upon TLR9 activation.

Conclusions:

• Stress significantly impairs anti-tumor immunity by suppressing B cell responses via corticosterone.
• Gut microbiota-derived phage DNA is a critical factor initiating TLR9 activation and subsequent corticosterone release from CAFs.
• This study reveals a novel bacteria-driven mechanism of immune suppression in cancer.