Adiponectin was discovered in 1995 by Phillip Scherer’s research group and described as a novel serum protein similar to C1q, being produced exclusively in adipocytes.1 Adiponectin represents an anti-inflammatory, anti-diabetic and anti-fibrotic adipokine that is highly abundant in human plasma. Adiponectin is induced during adipocyte differentiation and secreted from mature adipocytes into the blood stream where it circulates as homo-trimeric, hexameric, nonameric and higher molecular weight isoforms. Mutations in the gene encoding adiponectin result in an impaired multimer formation and cause lower levels of high-molecular weight isoforms in the plasma as well as a reduced abundance of all isoforms due to a disturbed secretion from the adipocyte.2 There are two receptors for adiponectin, AdipoR1 and AdipoR2, which are expressed in a wide variety of organs and cell types. The full-length and the truncated globular isoforms of adiponectin exhibit different receptor binding activities. Processes leading to a cleavage of the full-length protein and the exact mode of receptor interaction of different isoforms are only poorly understood. Adiponectin represents the only adipokine that is downregulated in obesity. Adiponectin exerts pleiotropic effects in several organs and its role in metabolism3 and in inflammation,4^–7 in general, are reviewed elsewhere.

Obesity can be regarded as a chronic and low-grade state of inflammation8 and the interpretation of the role of the adipose tissue has developed from a simple energy store to a highly active endocrine,9 inflammatory5 and immunological4 organ. In the context of obesity, the adipose tissue undergoes an inflammatory transformation10 and becomes infiltrated by significant amounts of macrophages.8 11 Since adiponectin is secreted by intra-abdominal adipose tissue and acts on monocytes in an anti-inflammatory way, it seems reasonable to review the role of adiponectin with respect to inflammatory gastrointestinal diseases, especially to those …