Background and purpose: Excessive inflammation in sepsis causes microvascular thrombosis and thrombocytopenia associated with organ dysfunction and high mortality. The present studies aimed to investigate whether inhibition of dipeptidyl peptidase-4 (DPP-4) and supplementation with glucagon-like peptide-1 (GLP-1) receptor agonists improved endotoxaemia-associated microvascular thrombosis via immunomodulatory effects.
Experimental approach: Endotoxaemia was induced in C57BL/6J mice by a single injection of LPS (17.5 mg kg-1 for survival and 10 mg kg-1 for all other studies). For survival studies, treatment was started 6 h after LPS injection. For all other studies, drugs were injected 48 h before LPS treatment.
Key results: Mice treated with LPS alone showed severe thrombocytopenia, microvascular thrombosis in the pulmonary circulation (fluorescence imaging), increased LDH activity, endothelial dysfunction and increased markers of inflammation in aorta and whole blood (leukocyte-dependent oxidative burst, nitrosyl-iron haemoglobin, a marker of nitrosative stress, and expression of inducible NOS). Treatment with the DPP-4 inhibitor linagliptin or the GLP-1 receptor agonist liraglutide, as well as genetic deletion of DPP-4 (DPP4-/- mice) improved all these parameters. In GLP-1 receptor-deficient mice, both linagliptin and liraglutide lost their beneficial effects and improvement of prognosis. Incubation of platelets and cultured monocytes (containing GLP-1 receptor protein) with GLP-1 receptor agonists inhibited the monocytic oxidative burst and platelet activation, with a GLP-1 receptor-dependent elevation of cAMP levels and PKA activation.
Conclusions and implications: GLP-1 receptor activation in platelets by linagliptin and liraglutide strongly attenuated endotoxaemia-induced microvascular thrombosis and mortality by a cAMP/PKA-dependent mechanism, preventing systemic inflammation, vascular dysfunction and end organ damage.
Linked articles: This article is part of a themed section on Redox Biology and Oxidative Stress in Health and Disease. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.12/issuetoc.
© 2016 The British Pharmacological Society.