Glycation and acetylation sites on fibrinogen in plasma fibrin clot of patients with type 2 diabetes: Effects of low-dose acetylsalicylic acid.

Acetylsalicylic acid (ASA) and type 2 diabetes mellitus (T2DM) affect fibrin clot properties through fibrinogen acetylation or glycation. We aimed to identify glycation and acetylation sites on fibrinogen in plasma fibrin clot of T2DM patients with respect to effects of ASA and fibrin clot properties. In fibrin clots generated from plasma of 9 T2DM patients, we performed mass-spectrometric analysis of Nε-fructosyl-(FL), Nε-carboxyethyl-(CEL) and Nε-carboxymethyl-lysine (CML), and acetylation sites, before and after one-month administration of 75 mg/d ASA confirmed with determination of thromboxane B2 concentration (TXB), along with clot permeability and lysis time, and thrombin generation. In the proteomic analysis, 216 proteins were identified. Among 10 glycation sites identified in α, 10 in β and 6 in γ fibrinogen chain, there were 17 FL, 5 CEL and 4 CML sites. Some of glycation sites in fibrinogen were previously reported to be involved in cross-linking by factor XIII (αK-208, αK-448 and αK-539) and plasmin cleavage (αK-81). There were 7 acetylation sites in α and β chains, and none in fibrinogen γ chain. Two acetylation sites were identical with FL sites (αK-195 and β-247), while one with CML site (βK-353). In 7 patients with low post-ASA TXB, intensity of acetylation, as well as clot properties were unaffected by ASA. This study identifies glycation and acetylation sites on fibrinogen in plasma fibrin clot of T2DM and supports the view that low-dose ASA does not increase fibrinogen acetylation in T2DM. Our findings suggest that glycation may block sites previously identified to be acetylated in vitro.