PB0856 - Antiplatelet Effects of Hydroxychloroquine in Patients with Systemic Lupus Erythematosus evaluated by Total Thrombus-formation Analysis System (T-TAS)

Monday, June 24, 2024

13:45 – 14:45 ICT

Room: Exhibition Hall

Presenting Author(s)

Daisuke Hiraoka, MD

MD
Department of Hematology, Clinical Immunology and Infectious Diseases, Ehime University Graduate School of Medicine
Toon, Ehime, Japan

Co-Author(s)

TH

Takatsugu Honda

Clinical Laboratory Technician
Clinical Laboratory Department, Ehime University Hospital
Toon, Ehime, Japan
TN

Toshiyuki Niiya

Clinical Laboratory Technician
Clinical Laboratory Department, Ehime University Hospital
Toon, Ehime, Japan
EH

Erika Horimoto

MD
Department of Hematology, Clinical Immunology and Infectious Diseases, Ehime University Graduate School of Medicine
Toon, Ehime, Japan
KH

Kenta Horie

MD
Department of Hematology, Clinical Immunology and Infectious Diseases, Ehime University Graduate School of Medicine
Toon, Ehime, Japan
HY

Hitoshi Yamasaki

MD
Internal medicine, Saiseikai Imabari Hospital
Imabari, Ehime, Japan
JI

Jun Ishizaki

MD, PhD
Department of Hematology, Clinical Immunology and Infectious Diseases, Ehime University Graduate School of Medicine
Toon, Ehime, Japan
TM

Takuya Matsumoto

MD, PhD
Department of Hematology, Clinical Immunology and Infectious Diseases, Ehime University Graduate School of Medicine
Toon, Ehime, Japan
KS

Koichiro Suemori

MD, PhD
Department of Hematology, Clinical Immunology and Infectious Diseases, Ehime University Graduate School of Medicine
Toon, Ehime, Japan
HH

Hitoshi Hasagawa

MD, PhD
Rheumatic center, Ozu Memorial Hospital
Ozu, Ehime, Japan
JY

Jun Yamanouchi

MD, PhD
Department of Hematology, Clinical Immunology and Infectious Diseases, Ehime University Graduate School of Medicine
Toon, Ehime, Japan
KT

Katsuto Takenaka

MD, PhD
Department of Hematology, Clinical Immunology and Infectious Diseases, Ehime University Graduate School of Medicine
Toon, Ehime, Japan

Background: Hydroxychloroquine (HCQ) has been shown to reduce thrombotic events in patients with systemic lupus erythematosus (SLE), but the mechanisms underlying its anti-thrombotic effect remain unclear. The Total Thrombus-formation Analysis System (T-TAS) allows analysis of platelet thrombus formation under flow condition by applying whole blood into collagen-coated capillaries and recording pressure waveforms until flow obstruction due to thrombus formation.

Aims: This study aims to investigate the antiplatelet effects of HCQ in SLE patients using T-TAS.

Methods: This is a single-center cross-sectional study. This study included 57 SLE patients who met the following criteria: platelet count >130,000 /μmL, hematocrit between 25% and 50%. We measured PL-AUC10 (area under the pressure curve for 10 minutes) using T-TAS and analyzed its association with HCQ use. Additionally, HCQ was added to whole blood from ten healthy individuals to achieve concentrations of 0, 1, 2, and 10 μg/mL, and PL-AUC10 was measured.

Results: The median age was 44 years (IQR 36-56), with 49 females, and a median disease duration of 10 years (3-19). No significant difference in PL-AUC10 was found between HCQ non-users (n=18) and HCQ users (n=39) (377.5 vs 357.9, p=0.21). However, HCQ/BW (body weight) ≥5 mg/kg group (n=14) had significantly lower PL-AUC10 than < 5 mg/kg group (n=25) (283.3 vs 380.4, p=0.0004). A negative correlation was observed between HCQ/BW and PL-AUC10 (rs=-0.47, p=0.002). Furthermore, with the increase in HCQ concentration in whole blood from healthy individuals, there was a decreasing trend in PL-AUC10. Compared to HCQ concentration of 0 μg/mL, significant decreases in PL-AUC10 were observed at 1, 2, and 10 μg/mL (p=0.037, p=0.009, and p=0.014, respectively).

Conclusion(s): We demonstrated, for the first time, the concentration-dependent antiplatelet effects of HCQ under conditions simulating the physiological environment by using T-TAS. These findings would provide supporting evidence for the thromboprotective effects of HCQ in SLE patients.