Interleukin-34 sustains inflammatory pathways in the gut

Area of Science:

• Gastroenterology
• Immunology
• Molecular Biology

Background:

• Inflammatory bowel disease (IBD) involves tissue damage driven by monocytes/macrophages.
• These immune cells produce inflammatory cytokines and chemokines in response to stimuli.
• Interleukin-34 (IL-34) is a key regulator of monocyte and macrophage functions.

Purpose of the Study:

• To investigate the expression and role of IL-34 in IBD.
• To determine if IL-34 contributes to the inflammatory processes in Crohn's disease (CD) and ulcerative colitis (UC).

Main Methods:

• Quantified IL-34 mRNA and protein levels in inflamed and uninvolved IBD tissues.
• Assessed IL-34 expression in lamina propria mononuclear cells (LPMCs).
• Investigated the effects of IL-34 on cytokine production and the impact of IL-34 neutralization.

Main Results:

• IL-34 expression was significantly increased in inflamed mucosa of CD and UC patients compared to controls.
• IL-34 was upregulated in normal LPMCs by tumor necrosis factor-alpha (TNF-α) and Toll-like receptor (TLR) ligands.
• IL-34 levels decreased in IBD patients treated with infliximab.
• IL-34 stimulation enhanced TNF-α production via ERK1/2 pathway.
• Neutralizing IL-34 reduced TNF-α and IL-6 synthesis in IBD explants.

Conclusions:

• IL-34 is upregulated in the inflamed tissues of IBD patients.
• IL-34 appears to contribute to the inflammatory response in IBD.
• Targeting IL-34 may offer a therapeutic strategy for IBD.