Pediatric Acute Liver Failure & Antiphospholipid Syndrome
The antiphospholipid syndrome (APS) is an entity on its own (also known as primary APS) and is also associated with systemic lupus erythematosus (SLE). Prevalence of APS in SLE is approximately 25%(Singh et al. 2013). The pathophysiology of this syndrome remains unclear as is the why/when of antiphospholipid antibodies (aPL) generation. A combination of genetic and environmental factors play a role. Known triggers are commonly viral and bacterial infections. Trauma, surgery, immune abnormalities, anticoagulation withdrawal, parasitic and fungal infections, along with some malignancies have also been connected to the etiology of this condition.
APS is defined by presence of aPL and a vascular thrombosis and/or complication of pregnancy. The thrombotic episodes range from superficial thrombophlebitis to myocardial infarction, stroke, and catastrophic APS (CAPS). CAPS may develop in less than 1% of APS patients and involves multiple blood clots that develop over a short time frame. These clots impair microcirculation and lead to multisystem organ injury most commonly in brain, lungs, and kidneys.
More recently, research has shown a coagulopathy associated with COVID-19, which suggests an immune-mediated pathway reminiscent of APS and the severe form of CAPS(Serrano et al. 2021). Xiao et al. reported COVID patients with multiple aPL positivities had a higher incidence of cerebral infarction compared to patients who were negative(Xiao et al. 2020). Complement activation has been linked to COVID-19 and contributes to APS pathogenesis (in murine models); the association between the two needs further investigation(Fischetti et al. 2005).