Inflammation, not hyperhomocysteinemia, is related to oxidative stress and hemostatic and endothelial dysfunction in uremia

Inflammation, not hyperhomocysteinemia, is related to oxidative stress and hemostatic and endothelial dysfunction in uremia.BackgroundSeveral cardiovascular risk factors are present in patients with chronic renal failure (CRF), among which are systemic inflammation and hyperhomocysteinemia. Increased oxidative stress, endothelial activation/dysfunction, and coagulation activation are considered integral components of the inflammatory response, but have also been proposed as mediators of plasma homocysteine (tHcy)-induced cell damage. Using correlation analysis, we assessed the relative contributions of inflammation and hyperhomocysteinemia in the abnormal oxidative stress, endothelial activation/dysfunction, and hemostasis activation in patients with CRF.MethodsThe relationships of inflammatory proteins and tHcy with plasma markers of these processes were studied in 64 patients with CRF (serum creatinine 526 ± 319 μmol/L) on conservative treatment, comparing the results with healthy controls (N = 15 to 40, depending on the measured variable) of similar sex and age.ResultsPatients had significant increases in inflammatory cytokines (TNF-α and IL-8) and acute-phase proteins (C-reactive protein, fibrinogen and α1-antitrypsin). tHcy was increased in 87.5% of patients (mean = 27.1 μmol/L, range 6.5 to 118). Patients had significant increases in (1) indices of oxidative stress: TBARS (thiobarbituric acid-reactive species), a marker of lipid peroxidation and AOPP (advanced oxidation protein products), a marker of protein oxidation; (2) endothelial cell markers such as von Willebrand factor (vWF:Ag), soluble ICAM-1 and soluble thrombomodulin (sTM); (3) markers of intravascular thrombin generation: thrombin-antithrombin complexes (TAT) and prothrombin fragment F1+2 (PF1+2); and (4) indices of activation of fibrinolysis: plasmin-antiplasmin complexes (PAP), fibrin degradation products (FnDP) and fibrinogen degradation products (FgDP). tHcy was significantly correlated with plasma creatinine (r = 0.29, P < 0.018) and with serum folate (r = -0.38, P < 0.002). However, no significant correlations were observed between tHcy and TBARS, AOPP, vWF:Ag, sICAM-1, sTM, TAT, F1+2, sTF, PAP, FnDP, and FgDP. Conversely, acute-phase proteins showed significant, positive correlations with most markers of oxidative stress, endothelial dysfunction and hemostatic activation.ConclusionsSystemic inflammation, which is closely associated with augmented oxidative stress, endothelial cell dysfunction and hemostatic activation, emerges as a major cardiovascular risk factor in CRF. tHcy is unrelated to these events. Thus, alternative mechanisms through which hyperhomocysteinemia could predispose to vascular lesion and thrombotic events in CRF needs to be investigated

<i>E</i>. <i>coli</i> O111 induced platelet-dependent TF procoagulant activity, involving TLR4 activation.

<p><i>E</i>. <i>coli</i> O111 increased FXa generation compared to N-S platelets (***p = 0.0005, n = 8) in assays without external source of TF and phospholipids. The amount of FXa generated was not significantly different than that of platelets stimulated with VWF+Ris (**p = 0.004, n = 8). TLR4 inhibition resulted in a ±-50% reduction in the generated FXa with strain O111 (**p = 0.004, n = 8), but did not influence the FXa generated by VWF+Ris activation of platelets (A). TRAP stimulated platelets did not generated FXa (B). Data analyzed by Paired t test, two-tailed. Pre-incubation of platelets with an inhibitory α-GPIbα MoAb (AP1) did not affect the FXa generated by <i>E</i>. <i>coli</i> but instead, reduce significantly the FXa triggered in platelets with VWF+Ris (*p = 0.03, n = 6) (C). Pre-incubation of platelets with a non-immune irrelevant IgG did not induced significant changes in FXa generation when stimulated with bacteria or VWF+Ris (n = 4) (C). Data were analyzed with Wilcoxon signed rank test, two tails.</p