The Role of Neutrophil Extracellular Traps (NETs) in the Pathogenesis of Systemic Lupus Erythematosus and Antiphospholipid Syndrome

Insight into antiphospholipid syndrome: the role and clinical utility of neutrophils extracellular traps formation

Antiphospholipid syndrome (APLS) is a systemic immune dysregulation distinguished by repetitive complications and pregnancy loss in the absence of definite etiology. Most research focuses on the laboratory detection and clinical features of APLS, but its precise etiology remains to be deeply explored. NETosis is a newly developed theory in the pathophysiology of APLS which may serve as the missing bridge between coagulation and inflammation reaching the disease progression and severity. We aimed in this study to navigate the prognostic role of NETosis in thrombotic APLS. Our study included 49 newly diagnosed APLS patients (both 1ry and 2ry) who met clinical and laboratory criteria as per the international consensus statement on the update of the classification criteria for definite APLS and were sub-classified according to the occurrence of thrombotic events in thrombotic and non-thrombotic types. In addition, 20 sex and age-matched reactive subjects and 20 sex and age-matched healthy volunteer controls were enrolled. NETosis formation was assessed by measuring serum Myeloperoxidase (MPO) and Histones level using the enzyme-linked immunosorbent assay (ELISA) technique. Both MPO and Histones levels were able to discriminate among APLS cases from normal controls, showing significant cutoffs of > 2.09 ng/ml for MPO and > 1.45 ng/ml for Histones (AUC values were 0.987and 1.000, respectively). These values can be used as predictors for NETosis pathophysiology in APLS patients. Additionally, these markers demonstrated a significant association with several prognostic indicators, including thrombosis, higher PT and INR, and lower hemoglobin (Hb) levels which are supposed to be ameliorated by using NETs inhibitors. In conclusion, we suggest that measuring NETosis markers, MPO, and Histones, in the early course of APLS using proposed cutoff values will facilitate the timely initiation of anti-NETosis therapy and improve the overall prognosis, particularly for patients with thrombotic APLS.

Insight into antiphospholipid syndrome: the role and clinical utility of neutrophils extracellular traps formation

Antiphospholipid syndrome (APLS) is a systemic immune dysregulation distinguished by repetitive complications and pregnancy loss in the absence of definite etiology. Most research focuses on the laboratory detection and clinical features of APLS, but its precise etiology remains to be deeply explored. NETosis is a newly developed theory in the pathophysiology of APLS which may serve as the missing bridge between coagulation and inflammation reaching the disease progression and severity. We aimed in this study to navigate the prognostic role of NETosis in thrombotic APLS. Our study included 49 newly diagnosed APLS patients (both 1ry and 2ry) who met clinical and laboratory criteria as per the international consensus statement on the update of the classification criteria for definite APLS and were sub-classified according to the occurrence of thrombotic events in thrombotic and non-thrombotic types. In addition, 20 sex and age-matched reactive subjects and 20 sex and age-matched healthy volunteer controls were enrolled. NETosis formation was assessed by measuring serum Myeloperoxidase (MPO) and Histones level using the enzyme-linked immunosorbent assay (ELISA) technique. Both MPO and Histones levels were able to discriminate among APLS cases from normal controls, showing significant cutoffs of > 2.09 ng/ml for MPO and > 1.45 ng/ml for Histones (AUC values were 0.987and 1.000, respectively). These values can be used as predictors for NETosis pathophysiology in APLS patients. Additionally, these markers demonstrated a significant association with several prognostic indicators, including thrombosis, higher PT and INR, and lower hemoglobin (Hb) levels which are supposed to be ameliorated by using NETs inhibitors. In conclusion, we suggest that measuring NETosis markers, MPO, and Histones, in the early course of APLS using proposed cutoff values will facilitate the timely initiation of anti-NETosis therapy and improve the overall prognosis, particularly for patients with thrombotic APLS.

Screening of natural inhibitors against peptidyl arginine deiminase 4 from herbal extracts by a high-performance liquid chromatography ultraviolet-visible based method

Peptidyl arginine deiminase 4 (PAD4) is an important biocatalytic enzymes involved in the conversion of protein arginine to citrulline, its dysregulation has a great impact on many physiological processes. Recently, PAD4 has emerged as a potential therapeutic target for the treatment of various diseases including rheumatoid arthritis (RA). Traditional Chinese Medicines (TCMs), also known as herbal plants, have gained great attention by the scientific community due to their good therapeutic performance and far fewer side effects observed in the clinical treatment. However, limited researches have been reported to screen natural PAD4 inhibitors from herbal plants. The color developing reagent (COLDER) or fluorescence based methods have been widely used in PAD4 activity assay and inhibitor screening. However, both methods measure the overall absorbance or fluorescence in the reaction solution, which are easy to be affected by the background interference due to colorful extracts from herbal plants. In this study, a simple, and robust high-performance liquid chromatography ultraviolet-visible (HPLC-UV) based method was developed to determine PAD4 activity. The proposed strategy was established based on COLDER principle, while used hydrophilic l-arginine instead of hydrophobic N-benzoyl-l-arginine ethyl ester (BAEE) as a new substrate to determine PAD4 inhibition activity of herbal extracts. The herbal extracts and PAD4 generated hydrophobic l-citrulline were successfully separated by the HPLC, and the developed method was optimized and validated with a known PAD4 inhibitor (GSK484) in comparison with COLDER assay. The IC50 value of GSK484 measured by HPLC-UV method was 153 nM, and the detection limit of the citrulline was 0.5 nmol, respectively, with a linear range of 0.5 nmol to 20 nmol. The IC50 value of the HPLC-UV method was improved by nearly three times compared with COLDER assay (527 nM), and the results indicated the reliability of PAD4 inhibition via HPLC-UV method. The inhibitory effect against PAD4 were fast and accurately screened for the twenty-four extracts from eight herbs. Among them, Ephedra Herba extracts showed significant inhibitory activity against the PAD4 with the IC50 values of three extracts (ethanol, ethyl acetate and water) ranging from 29.11 μg/mL to 41.36 μg/mL, which may help researchers to discover novel natural compounds holding high PAD4 inhibition activity.