PI3K Signaling in Dendritic Cells Aggravates DSS-Induced Colitis

Area of Science:

• Immunology
• Gastroenterology
• Cell Biology

Background:

• Aberrant innate immune responses to gut microbiota contribute to inflammatory bowel diseases (IBD) pathogenesis.
• Signaling pathways in innate immune cells that modulate adaptive immunity in IBD are not fully understood.

Purpose of the Study:

• To investigate the role of the PI3K/PTEN signaling pathway in dendritic cells (DCs) in IBD pathogenesis.
• To elucidate the mechanisms by which DCs influence adaptive immune responses in colitis.

Main Methods:

• Utilized a dextran sodium sulfate (DSS)-induced colitis model in mice.
• Generated DC-specific PTEN knockout (PTEN^ΔDC) mice.
• Administered antibiotics to deplete gut microbiota and used IL-6 receptor (IL-6R) blocking antibodies.
• Performed adoptive transfer of PTEN-deficient DCs into wild-type (WT) recipients.

Main Results:

• PTEN deficiency in DCs exacerbated DSS-induced colitis, increasing Th1 cell responses and mortality.
• Antibiotic treatment and IL-6R blockade rescued mortality in PTEN^ΔDC mice.
• Adoptive transfer of PTEN^-/- DCs worsened colitis and mortality in WT mice.

Conclusions:

• The PI3K/PTEN signaling pathway in DCs promotes IBD pathology.
• This pathway enhances IL-6 production, which drives detrimental IL-6-mediated Th1 responses.
• Targeting DC PI3K signaling or IL-6 may be a therapeutic strategy for IBD.