Whether IL-34 takes on either a pro- or anti-inflammatory role, is ambiguous and may depend on pathologic conditions as studies of certain diseases (e.g., acute kidney injury, inflammatory bowel disease, lupus nephritis, Sjögren's syndrome) characterized IL-34 as a pro-inflammatory factor (25–29), while other clinical settings (e.g., atopic dermatitis, autoimmune hepatitis, lung cancer, sepsis) identified IL-34 as a mediator of anti-inflammatory responses (30–33). Here, IL34 is linked to inflammatory bowel disease.