Hydroxychloroquine restores trophoblast fusion affected by antiphospholipid antibodies

Abstract

Summary. Background: Obstetric antiphospholipid syndrome (APS) is defined by pregnancy complications associated with antiphospholipid antibodies (aPL). The mechanisms of the pathogenic effects of aPL in pregnancy are poorly understood. Toll-like receptors (TLR) have been implicated previously in APS. Objectives: The aims of our study were (1) to determine aPL effects on trophoblastic cell fusion and differentiation, (2) to identify which TLR is involved in this process, and (3) to evaluate the efficacy of hydroxychloroquine (HCQ) to counteract the effects of aPL. Methods: BeWo cells are a model for trophoblast fusion and differentiation. Fusion index was assessed by immunocytochemical examination, and biochemical differentiation by using ELISA-measured b-human choronic gonadotropin hormone (b-hCG) secretion. We used three types of aPL to study their effect on cell fusion and differentiation: aPL derived from obstetric APS patients and affinity purified and polyclonal rabbit anti-b2-glycoprotein-1 (anti-b2GP1) antibodies. Experiments on fusion were confirmed using primary cytotrophoblastic cells. Results: All of the types of aPL used decreased the fusion index in BeWo and primary trophoblastic cells (64%, 52%, and 41% for BeWo cells and 67% and 62% for primary cells, respectively), and anti-b2GP1 antibodies decreased hCG secretion in BeWo cells (41%). To block TLR4 antibodies or to abolish TLR4 cell surface expression restored fusion index in both cell types and b-human choronic gonadotropin hormone excretion in BeWo cells. HCQ treatment induced the same effect and decreased TLR4 mRNA (40% and 35%, respectively) and protein expressions (62% and 42%, respectively) in BeWo cells. Conclusion: Anti-b2GP1 antibodies decrease trophoblastic differentiation via TLR4. This effect is restored by HCQ, suggesting its therapeutic interest in APS pregnancies.

Update on the pathogenesis and treatment of the antiphospholipid syndrome

“…Hydroxychloroquine (HCQ) provides another option in refractory obstetric APS: its addition to standard treatment allowed a decrease in the rate of pregnancy wastage from 81 to 19% [33 & ]. Such clinical efficacy is consistent with its well known in-vitro properties: HCQ not only reduces aPL binding to syncytiotrophoblasts and restores the placental expression of AnnexinA5 [25 && ], but also downregulates TLR4 expression, thus preventing the antib2GPI antibody-induced impairment of trophoblast differentiation [34] and reverses aPL-induced inhibition of pro-migratory IL-6, thus enhancing trophoblast migration [35].…”

Pregnancy and primary Sjögren’s syndrome: management and outcomes in a multicentre retrospective study of 54 pregnancies

“…Compared with the rate of miscarriages among clinically recognized pregnancies in the general population (12-15%) (24,25), women with pSS are at a higher risk of miscarriage, with approximately 30% experiencing miscarriages in our study. Immunological disturbances may be associated with the mechanism of spontaneous abortion, but the present study did not allow us to evaluate the role of aPL antibodies (encountered in 22% of patients with pSS), which are involved in trophoblastic differentiation and invasion through Toll-like receptor 4 (TLR4) (26). However, the presence of aPL antibodies in pSS patients is not associated with the clinical events of APS (27,28).…”

“…However, the limited number of women examined (n = 6) limits our analysis of the potential positive impact of HCQ. Experimental models tend to show that HCQ counters the negative effects of aPL antibodies on trophoblastic differentiation through TLR4 (26). Other immunological disturbances associated with pSS may play a role in placentation and could be restored through immunomodulation therapies.…”

The impact of hydroxychloroquine treatment on pregnancy outcome in women with antiphospholipid antibodies

“…17 Also, it has been reported that hydroxychloroquine restores trophoblast fusion that is affected by aPL. 18 These studies suggest that hydroxychloroquine may improve pregnancy outcome in women with aPL, especially in those with recurrent pregnancy loss refractory to conventional treatment. 19 Several studies have assessed the effect of hydroxychloroquine on pregnancies in women with SLE and demonstrated that hydroxychloroquine is safe in pregnancy.…”