Correlation between erythrocyte antioxidant activity, lipid peroxidation, and disease activity in patients with Behçet's disease

Elevated serum fibrinogen levels in Chinese patients with minor recurrent aphthous stomatitis: An observational study

Fibrinogen is a protein that reflects systemic inflammation and regulates the immune response to disease. However, there is a scarcity of data on fibrinogen in recurrent aphthous stomatitis (RAS). We aimed to test the hypothesis that fibrinogen is involved in the aetiology of RAS. Between November 2016 and November 2018, we included 109 minor RAS patients and 29 age- and sex-matched controls in a single-center, observational study. Their clinical history and ulcer manifestations led to the diagnosis of minor RAS. The ulcer severity score (USS) was used to assess disease severity, and fibrinogen was also collected. We conducted three analyses: Analysis 1 (comparison of fibrinogen levels between patients and controls), Analysis 2 (comparison of fibrinogen levels between high and low USS patients) and Analysis 3 (comparison of fibrinogen levels between before and after anti-inflammatory treatment in patients). The fibrinogen levels in the 109 minor RAS patients were statistically higher than in the 29 controls (mean [SD], 2.6 [0.5] vs. 2.3 [0.3]; Student's t-test, p < 0.001). However, there were no significant differences in fibrinogen levels among the 43 patients with high USS and the 39 patients with low USS (mean [SD], 2.7 [0.5] vs. 2.6 [0.4]; Student's t-test, p = 0.278). Furthermore, fibrinogen levels were significantly higher before anti-inflammatory treatment in comparison to those after anti-inflammatory treatment in the 35 paired patients (mean [SD], 2.6 [0.4] vs. 2.5 [0.4]; Student's t-test, p = 0.026). Interestingly, fibrinogen levels were significantly higher in the 35 paired patients after anti-inflammatory treatment compared to the 29 control subjects (mean [SD], 2.5 [0.4] vs. 2.3 [0.3]; Student's t-test, p = 0.026]. Fibrinogen may play a role in the aetiology of RAS and may be a drug target for RAS treatment. Clinicians should be alert that high serum fibrinogen levels might be associated with the risk of RAS.

Behçet's syndrome as a tool to dissect the mechanisms of thrombo-inflammation: clinical and pathogenetic aspects

Behçet's syndrome (BS) is a complex disease with different organ involvement. The vascular one is the most intriguing, considering the existence of a specific group of patients suffering from recurrent vascular events involving the venous and, more rarely, the arterial vessels. Several clinical clues suggest the inflammatory nature of thrombosis in BS, especially of the venous involvement, thus BS is considered a model of inflammation-induced thrombosis. Unique among other inflammatory conditions, venous involvement (together with the arterial one) is currently treated with immunosuppressants, rather than with anti-coagulants. Although many in-vitro studies have suggested the different roles of the multiple players involved in clot formation, in-vivo models are crucial to study this process in a physiological context. At present, no clear mechanisms describing the pathophysiology of thrombo-inflammation in BS exist. Recently, we focused our attention on BS patients as a human in-vivo model of inflammation-induced thrombosis to investigate a new mechanism of clot formation. Indeed, fibrinogen displays a critical role not only in inflammatory processes, but also in clot formation, both in the fibrin network and in platelet aggregation. Reactive oxygen species (ROS)-derived modifications represent the main post-translational fibrinogen alterations responsible for structural and functional changes. Recent data have revealed that neutrophils (pivotal in the pathogenetic mechanisms leading to BS damage) promote fibrinogen oxidation and thrombus formation in BS. Altogether, these new findings may help understand the pathogenetic bases of inflammation-induced thrombosis and, more importantly, may suggest potential targets for innovative therapeutic approaches.

Neutrophil Activation Promotes Fibrinogen Oxidation and Thrombus Formation in Behçet Disease

Background—

Behçet disease (BD) is a systemic vasculitis with a broad range of organ involvement, characterized by a multisystemic, immune-inflammatory disorder involving vessels of all sizes and often complicated by thrombosis. Systemic redox imbalance and circulating neutrophil hyperactivation have been observed in BD patients and are thought to be responsible for impaired coagulation. We here focused on the pathogenetic mechanisms potentially linking immune cell activation and thrombosis, and specifically examined whether neutrophil activation can affect fibrinogen modifications and consequently elicit thrombosis.

Methods and Results—

Blood samples were collected from 98 consecutive BD patients attending our dedicated Center and from 70 age- and sex-matched healthy controls; in all patients fibrinogen function and structure, fibrin susceptibility to plasmin-lysis, plasma redox status, leukocyte oxidative stress markers, and possible reactive oxygen species sources were examined. Thrombin-catalyzed fibrin formation and fibrin susceptibility to plasmin-induced lysis were significantly impaired in BD patients ( P <0.001). These findings were associated with increased plasma oxidative stress markers ( P <0.001) and with a marked carbonylation of fibrinogen ( P <0.001), whose secondary structure appeared deeply modified. Neutrophils displayed an enhanced NADPH oxidase activity and increased reactive oxygen species production ( P <0.001), which significantly correlated with fibrinogen carbonylation level ( r 2 =0.33, P <0.0001), residual β-band intensity ( r 2 =0.07, P <0.01), and fibrinogen clotting ability ( r 2 =0.073, P <0.01)

Conclusions—

In BD patients, altered fibrinogen structure and impaired fibrinogen function are associated with neutrophil activation and enhanced reactive oxygen species production whose primary source is represented by neutrophil NADPH oxidase.

The Significance of Serum Nitric Oxide Levels in Behçet's Disease and Recurrent Aphthous Stomatitis

Behçet's disease (BD) is an inflammatory multisystem disorder characterized by recurrent oral and genital aphthous ulcers, arthritis, uveitis, and thrombophlebitis; it can involve several organs. However, recurrent aphthous stomatitis (RAS) can be seen without a confirmed diagnosis of BD. Moreover, there is no way of predicting whether a patient with RAS will develop BD. Nitric oxide (NO) is a free radical synthesized from L-arginine by one of the family of nitric oxide synthase (NOS) enzymes. Increased production of NO during several inflammatory and infectious processes has been recently postulated. Our aim was to investigate the serum NO levels in patients with active and inactive BD and RAS. Forty-six patients with BD, 30 patients with RAS and 30 healthy controls were enrolled in the study. The patients with BD were separated into two groups: clinically active (n = 24) and inactive (n = 22). A blood sample was collected from all subjects in order to determine their serum NO levels. In patients with active BD, higher serum levels of NO metabolite were found in comparison with patients with inactive BD, in patients with RAS, or healthy controls (p < 0.05). We also found higher serum NO metabolite levels in patients with RAS than in healthy controls (p < 0.05). In patients with inactive BD, statistically significant higher levels of serum NO levels were found in comparison with the control group (p < 0.05). However, we found no statistically significant difference between the patients with inactive BD and RAS, which indicated that inactive BD cannot be distinguished from RAS by serum NO levels. We conclude that serum NO levels may be an important marker for estimating the severity of BD. However, further studies are needed to confirm our findings.

Decreased Total Antioxidant Response and Increased Oxidative Stress in Behcet's Disease

Behcet's disease (BD) is a chronic systemic inflammatory disease. Inflammatory reactions trigger the oxidative stress and oxidants decrease the level of antioxidants. In the present study, we aimed to determine serum oxidative/antioxidative status in patients with BD. Serum antioxidative status was evaluated by measuring total antioxidant capacity (TAC), paraoxonase 1, arylesterase, sulfhydryl groups and ceruloplasmin in patients with BD and in healthy controls. Serum oxidative status was evaluated by measuring total peroxide (TP), lipid hydroperoxides and oxidative stress index (OSI). OSI was calculated by percent ratio of TP to TAC. Serum levels of TAC, sulfhydryl groups and activities of paraoxonase 1, arylesterase, and ceruloplasmin were significantly lower in patients than in controls (p < 0.001 for all). In contrast, TP, lipid hydroperoxides and OSI values were significantly higher in patients than in controls (p < 0.001 for all). Further, the level of TAC was negatively correlated with the levels of TP, lipid hydroperoxides and OSI both in the BD (r = -0.578, p < 0.01; r = -0.559, p < 0.01 and r = -0.552, p < 0.01, respectively) and the control groups (r = -0.469, p < 0.05; r = -0.351, p < 0.05 and r = -0.391, p < 0.05, respectively). These results indicate that the oxidant parameters increased and antioxidant parameters decreased in patients with BD; therefore, these patients might have been exposed to oxidative stress. We suggest that impaired oxidant/antioxidant balance should be taken into consideration in the follow-up of patients with BD.