Dosage sanguin de l’hydroxychloroquine dans la prise en charge du lupus systémique : intérêts et limites

Hydroxychloroquine sulfate: A novel treatment for lipin-1 deficiency?

BACKGROUND

Lipin-1 deficiency is a life-threatening disease that causes severe rhabdomyolysis (RM) and chronic symptoms associated with oxidative stress. In the absence of treatment, Hydroxychloroquine sulfate (HCQ) was administered to patients off label use on a compassionate basis in order to improve their physical conditions.

METHODS

Eleven patients with LPIN1 mutations were treated with HCQ. Clinical and biological efficacy and tolerance were assessed, including pain and quality of life, physical capacities, cardiopulmonary parameters, creatine kinase levels and plasma proinflammatory cytokines. To explore a dose-dependent effect of HCQ, primary myoblasts from 4 patients were incubated with various HCQ concentrations in growth medium (GM) or during starvation (EBSS medium) to investigate autophagy and oxidative stress.

FINDINGS

Under HCQ treatment, patient physical capacities improved. Abnormal cardiac function and peripheral muscle adaptation to exercise were normalized. However, two patients who had the highest mean blood HCQ concentrations experienced RM. We hypothesized that HCQ exerts deleterious effects at high concentrations by blocking autophagy, and beneficial effects on oxidative stress at low concentrations. We confirmed in primary myoblasts from 4 patients that high in vitro HCQ concentration (10 µM) but not low concentration (1 µM and 0.1 µM) induced autophagy blockage by modifying endolysosomal pH. Low HCQ concentration (1 µM) prevented reactive oxygen species (ROS) and oxidized DNA accumulation in myoblasts during starvation.

INTERPRETATION

HCQ improves the condition of patients with lipin-1 deficiency, but at low concentrations. In vitro, 1 µM HCQ decreases oxidative stress in myoblasts whereas higher concentrations have a deleterious effect by blocking autophagy.

Efficacy and Safety of Hydroxychloroquine Therapy for Systemic Lupus Erythematosus Patients Depend on Administration Dose

Objective Hydroxychloroquine (HCQ) has been prescribed in Japan only relatively recently and is recommended for the treatment of skin lesions, arthritis and renal lesions according to the Japanese Guideline for the Management of systemic lupus erythematosus (SLE) (2019). However, the associations between the efficacy and safety and the HCQ dose in Japanese SLE patients remain unclear. We investigated the efficacy and safety of different HCQ doses in Japanese SLE patients with a low disease activity who were not receiving immunosuppressants. Methods The disease activity was evaluated using the SELENA-SLEDAI 2011 criteria, the Cutaneous Lupus Erythematous Disease Area and Severity Index (CLASI) and serum biomarkers. Safety was evaluated via the frequency of adverse events over a period of three months. Results We enrolled 61 SLE patients treated with HCQ and no additional immunosuppressive therapy for more than 3 months. HCQ was administered to 46 patients at the usual dose and to 15 cases at a lower than usual dose. Although the CLASI activity scores decreased significantly in both groups, the magnitude of this decrease was larger in the usual-dose HCQ group than in the low-dose HCQ group. SLEDAI scores and immunological activity were significantly improved only in the usual-dose HCQ group. In addition, changes in the serum complement levels in the usual-dose HCQ group were more dramatic than in the low-dose HCQ group six months after the initiation of HCQ administration. Adverse events were more frequent in the usual-dose HCQ group than in the low-dose HCQ group (30.4% and 13.3%, respectively). Conclusion HCQ therapy is effective for maintenance therapy of SLE patients. The usual dose of HCQ may have some advantage in ameliorating low complement levels.