A potential role for dendritic cell/macrophage-expressing DPP4 in obesity-induced visceral inflammation

Evidence from laboratory and animal studies provides groundwork for understanding mechanisms and potential before human studies continue.

• Level A · Stronger Clinical Evidence
• Level B · Emerging clinical evidence with positive signals
• Level C · Early human research exploring benefits
• Level D · Scientific groundwork from lab and animal studies
• Emerging · Emerging topic under active research

Abstract (original English)

Dipeptidyl peptidase-4 (DDP4) inhibitors target the enzymatic degradation of incretin peptides and represent a major advance in the treatment of type 2 diabetes. DPP4 has a number of nonenzymatic functions that involve its interaction with adenosine deaminase (ADA) and other extracellular matrix proteins. Here, we assessed the nonenzymatic role of DPP4 in regulating dendritic cell (DC)/macrophage-mediated adipose inflammation in obesity. Both obese humans and rodents demonstrated increased levels of DPP4 expression in DC/macrophage cell populations from visceral adipose tissue (VAT). The DPP4 expression increased during monocyte differentiation to DC/macrophages and with lipopolysaccharide (LPS)-induced activation of DC/macrophages. The DPP4 colocalized with membrane-bound ADA on human DCs and enhanced the ability of the latter to stimulate T-cell proliferation. The DPP4 interaction with ADA in human DC/macrophages was competitively inhibited by the addition of exogenous soluble DPP4. Knockdown of DPP4 in human DCs, but not pharmacologic inhibition of their enzymatic function, significantly attenuated the ability to activate T cells without influencing its capacity to secrete proinflammatory cytokines. The nonenzymatic function of DPP4 on DC may play a role in potentiation of inflammation in obesity by interacting with ADA. These findings suggest a novel role for the paracrine

Evidence level

Evidence from laboratory and animal studies provides groundwork for understanding mechanisms and potential before human studies continue.

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