The Antiphospholipid Antibody Syndrome Research in Patients with Retinal Venous Occlusion

IgG/IgM antiphospholipid antibodies present in the classification criteria for the antiphospholipid syndrome: a critical review of their association with thrombosis

Essentials The clinical value of IgM antibodies in thrombotic antiphospholipid syndrome (APS) is debated. By review of literature, we reconsidered the clinical value of IgM antibodies in thrombotic APS. More significant correlations with thrombosis were found for the IgG compared to IgM isotype. Unavailability of paired IgG/IgM results hampers evaluating the added value of IgM positivity. Click to hear Dr de Groot's perspective on antiphospholipid syndrome

SUMMARY

Background Despite the update of the classification criteria for the antiphospholipid syndrome (APS), difficulties persist in the identification of patients at risk for thrombosis. Current guidelines include assays detecting IgG/IgM anti-β2 -glycoprotein I and anti-cardiolipin antibodies, although the relevance of IgM antibodies has been debated. Objectives Through a review of the literature from 2001 to 2014, we aimed to formally establish the thrombotic risk stratification potential of IgM as compared with IgG anti-phospholipid antibodies (aPLs). Patients/methods One thousand two hundred and twenty-eight articles were selected by a computer-assisted search of the literature. Of the 177 studies that met our inclusion criteria, the clinical value of IgG/IgM aPLs was established through analysis of odds ratios for thrombosis or percentage of positives in the thrombotic population. Results/conclusions We clearly found more significant correlations with thrombosis for the IgG than for the IgM isotype. Nonetheless, in a minority of studies, significant associations with thrombosis were found for IgM but not IgG antibodies. The unavailability of paired results of IgG and IgM for each separate patient hampers evaluation of the added value of isolated IgM positivity. To fully take advantage of results obtained by future studies, we strongly encourage scientists to provide all studied information per patient. We planned a large multicenter study to investigate clinical associations of isolated/combined positivity for criteria/non-criteria aPLs. Importantly, because of the presence of non-pathogenic aPLs, quantitative assays are characterized by a high false-positivity rate. Optimization of functional assays, such as thrombin generation measuring the whole scheme of coagulation, may help to reduce APS-related morbidity and mortality.

Toll-like receptors play a crucial part in the pathophysiological activity of antiphospholipid antibodies

The antiphospholipid syndrome (APS) is a systemic autoimmune disease characterized by thrombosis, recurrent fetal loss and the presence of a variety of antiphospholipid antibodies (aPL), directed to phospholipids like Cardiolipin and phospholipid binding proteins like β2-glycoprotein I. Till date, the pathophysiological processes underlying these thrombotic events were still not fully understood. Recent data support the idea that the aPL might act via enhanced cytokine release due to activation of certain Toll-like receptors. The investigation of some of those mechanisms in more detail enlightens the involvement of the intracellular receptors TLR7 and TLR8 in a central point. Using patients’ IgG fractions and/or monoclonal aPL, either generated from mouse or from human B-cells for the stimulation experiments of monocytes, endothelial cells or dendritic cells, all these stimuli induced an enhanced expression and secretion of cytokines, especially TNFα, caused by specific regulation or activation of Toll-like receptors. Using specific agonists or inhibitors could confirm the causal connection of these stimulatory effects. This review focuses on the recent developments connecting the binding of aPL with the activity of Toll-like receptors, especially in monocytes, endothelial cells and dendritic cells.

Retinal vein occlusion: beyond the acute event

Retinal vein occlusion is a major cause of vision loss. We provide an overview of the clinical features, pathogenesis, natural history, and management of both branch retinal vein occlusion and central retinal vein occlusion. Several recent multicenter randomized clinical trials have been completed which have changed the approach to this disorder. Management of retinal vein occlusions can be directed at the underlying etiology or the resulting sequelae. Options include surgical intervention, laser photocoagulation, intravitreal pharmacotherapy, and sustained drug delivery devices.

Central retinal vein occlusion in primary antiphospholipid antibody syndrome

PURPOSE

To report a case of a 20-year-old healthy patient with central retinal vein occlusion in his right eye attributable to primary antiphospholipid antibody syndrome.

METHODS

A 20-year-old man with poor vision in the right eye and diffuse retinal hemorrhages was investigated for infections, autoimmune disease, diabetes, and hypertension. Testing for homocysteine, anticardiolipin antibodies, lupus anticoagulant, and functional assays for protein S and protein C was performed to detect a hypercoagulable state.

RESULTS

Laboratory investigations revealed elevated levels of IgG and M anticardiolipin antibodies. Long-term oral anticoagulants were given to reduce the risk of future thromboses.

CONCLUSION

Antiphospholipid antibodies play an important role in occlusive retinal vascular disorders, especially in young patients without any conventional risk factors.

Ocular manifestations in antiphospholipid syndrome

Antiphospholipid syndrome (APS) is characterized by increased hypercoagulability and divergent symptoms including ocular manifestations. In APS patients arterial and/or venous thromboses and repeated fetal loss are diagnosed in presence of antiphospholipid (aPL) antibodies. Antiphospholipid antibodies are heterogeneous group of immunoglobulins with different antigenic structure. Primary APS is defined in the absence of underlying disease, while secondary APS is seen within another pathological condition. In both primary and secondary APS ocular and neuroophthalmic manifestations, such as retinal arteritis, retinal venous occlusion, ischemic optic neuropathy, transient loss of vision - amaurosis fugax, diplopia and others can be diagnosed. In secondary APS occlusion of central retinal artery and vein (OACR, OVCR) is the most common finding, thus when found in younger patients it should be considered indicative of APS. Bilateral ocular changes are considered more significant since they affect both ocular function and life prognosis.