key: cord-0778516-ookbx0fj
authors: Xiao, Meng; Zhang, Yan; Zhang, Shulan; Qin, Xuzhen; Xia, Peng; Cao, Wei; Jiang, Wei; Chen, Huan; Ding, Xin; Zhao, Hua; Zhang, Hongmin; Wang, Chunyao; Zhao, Jing; Sun, Xuefeng; Tian, Ran; Wu, Wei; Wu, Dong; Ma, Jie; Chen, Yu; Zhang, Dong; Xie, Jing; Yan, Xiaowei; Zhou, Xiang; Liu, Zhengyin; Wang, Jinglan; Du, Bin; Qin, Yan; Gao, Peng; Lu, Minya; Hou, Xin; Wu, Xian; Zhu, Huadong; Xu, Yingchun; Zhang, Wen; Li, Taisheng; Zhang, Fengchun; Zhao, Yongqiang; Li, Yongzhe; Zhang, Shuyang
title: Brief Report: Anti‐phospholipid antibodies in critically ill patients with Coronavirus Disease 2019 (COVID‐19)
date: 2020-06-30
journal: Arthritis Rheumatol
DOI: 10.1002/art.41425
sha: 72403dbb187a5d072691c3c0ff6da4fc3c73ed24
doc_id: 778516
cord_uid: ookbx0fj

OBJECTIVES: Coagulopathy is one of the characteristics of critically ill patients with Coronavirus Disease 2019 (COVID‐19). Antiphospholipid antibodies (aPLs) contribute to coagulopathy, but their role in COVID‐19 remains unclear. We aimed to determine the prevalence and characteristics of aPLs in patients with COVID‐19. METHODS: Sera collected from 66 critically ill and 13 non‐critically ill patients with COVID‐19 were tested for anti‐cardiolipin (aCL) and anti‐β2‐glycoprotein 1 (aβ2GP1) (IgG, IgM, and IgA) and IgG aβ2GP1‐D1 by the chemiluminescence assay (CIA) and IgM and IgG anti‐phosphatidylserine/prothrombin (aPS/PT) by ELISA. RESULTS: aPLs were detected in 47.0% of critically ill patients (31/66), but not in patients with non‐critical conditions. IgA aβ2GP1 was the most common aPL, present in 28.8% (19/66) critically ill patients, followed by IgA aCL (25.8%,17/66) and IgG aβ2GP1 (18.2%,12/66). For multiple aPLs, IgA aβ2GP1+IgA aCL was the most common type (22.7%, 15/66), followed by IgA aβ2GP1+IgA aCL+ IgG aβ2GP1 (15.2%, 10/66). aPLs emerge around 35‐39 days post‐disease onset. Dynamic analysis of aPLs revealed 4 patterns based on persistence or transient appearance of the aPLs. Patients with multiple aPLs displayed significantly higher incidence of cerebral infarction (p=0.023). CONCLUSIONS: aPLs were common in critically ill patients. Multiple medium or high levels aPLs may help identify patients at risk of developing cerebral infarction. aPLs may be transient and disappear within a few weeks, but in genetically predisposed patients, COVID‐19 may trigger the development of “COVID‐19‐induced‐APS‐like‐syndrome”. Long‐term follow‐up on COVID‐19 patients positive for aPLs would be of great importance.

Keywords: COVID-19, antiphospholipid antibodies, coagulopathy, critically ill patients,

We 

Serum aCL and aβ2GP1 (IgG, IgM, and IgA) and IgG aβ2GP1-D1 were determined by the chemiluminescence assay (CIA) (INOVA) (10) . The cutoff values for positivity were set >20 U based on manufacturer's recommendations. IgG/IgM aPS/PT were determined by ELISA (INOVA) (11) . The cutoff values for positivity were set >30 U based on manufacturer's recommendations.

The detection of LA in human citrated plasma was performed by the HemosIL dRVVT Screen and

HemosIL dRVVT Confirm assays, as recommended by the International Society on Thrombosis and Haemostasis (ISTH).

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We first determined the prevalence and characteristics of aPLs in patients with COVID-19. When the manufacturer's recommended cut-off value of >20 CU was utilized, aPLs were detected in 47.0% of critically ill patients (31/66), but not in patients with non-critical conditions ( Next, we determined when the aPLs emerged in those patients. Among the 31 aPL-positive patients, we had sera from 10 patients who were negative for aPLs at early time-point and positive for aPLs at

This article is protected by copyright. All rights reserved Last, we assessed the clinical relevance of aPLs in critically ill patients with COVID-19 ( Table 1) . As mounting evidence suggest that multiple aPL positivity or moderate to high titers of aPLs display better clinical values comparted to single aPL positivity or low titers of aPLs. We divided aPLs positive group into single/multiple lo group (patients positive for single aPL or positive for more than one aPLs but the values of all aPLs was at low titers (<=40 CU), as previously described (13)) and multiple med/hi group (patients positive for more than one aPLs and the value of at least one aPL was at moderate titers (>40 CU)). The three critically ill groups displayed similar clinical and laboratory features, but the multiple med/hi group showed significantly higher incidence of cerebral infarction compared to

This article is protected by copyright. All rights reserved aPL-negative group (0 vs 33.3%, p=0.023), suggesting that aPLs may be helpful in predicting the occurrence of cerebral infarction during COVID-19.

The full spectrum of COVID-19 is still under intense investigation, but increasing evidence suggest that most critically ill patients suffer from coagulopathy (1) (2) (3) . aPLs have been considered as one of the mechanisms leading to a proinflammatory and hypercoagulable state. In this study, we found that aPLs were present in a substantial number of critically ill patients. Although it remains unclear whether aPLs contribute to the hypercoagulable state in COVID-19, our findings suggest a possibility that aPLs may be implicated in this process.

Infection-induced aPL production has been widely acknowledged (14, 15) . Of particular interest is that we found IgA, an isotype specialized in mucosal immunity, was the most common aPLs isotype. As COVID-19 mainly affects pulmonary and intestinal mucosa, the preferential production of IgA isotype may be associated with the breakage of mucosal immune tolerance. IgA aβ2GPI preferentially target the C-terminal portion of β2GPI (domain 4 and 5) (16), thus the presence of IgA aPLs may suggest a novel subgroup of clinically relevant APS in critically ill patients with COVID-19. Interestingly, we found that although IgA aCL and IgA aβ2GPI transiently appeared in a subgroup patient, they persisted in another subgroup patients. Unfortunately, we could not perform long-term follow-up. A prospective evaluation of those aPLs in COVID-19 patients is in great need to investigate whether these are persistent and pathogenic or require long-term anticoagulants.

While it remains unclear whether IgA aPLs are pathogenic in APS, in vivo mouse studies demonstrated that IgA aβ2GPI induced significantly larger thrombi and higher tissue factor (TF) levels

This article is protected by copyright. All rights reserved compared to controls (17) . IgA aβ2GPI are significantly and independently associated with arterial thrombosis and all thrombosis in patients with systemic lupus erythematosus (SLE) and APS (17) . In addition, IgA aβ2GPI has been described as an independent risk factor for acute myocardial infarction (16, 18) and acute cerebral ischaemia (19) . In this study, we found that patients with multiple aPLs, including IgA and IgG aβ2GPI and IgA and IgG aCL, displayed significantly higher incidence of cerebral infarction. Unfortunately, due to the critical condition of those patients as well as the limitation of the isolation ward, a large number of patients could not be screened by ultrasound, thus many thrombotic events may be underrepresented. It is also worth mentioning that the patients who 

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International consensus statement on an update of the classification criteria for definite antiphospholipid syndrome (APS)

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Antiphospholipid Antibodies Technical Task Force Report on Antiphospholipid Syndrome Clinical Features

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The authors declare no competing financial interests.

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Single/multiple lo refers to patients positive for a single aPL or positive for more than one aPLs but the values of all aPLs was <=40 CU. Multiple med/hi refers to patients positive for more than one aPLs and the value of at least one aPL was >40 CU. p value was calculated with a Kruskal-Wallis test followed by Dunnett's T2 test. For cerebral infarction during COVID-19 infection, p-value between aPLs negative group and multiple aPLs positive group was 0.023, p-value between aPLs single positive group and multiple aPLs positive group was 0.101.

Antiphospholipid antibodies (aPLs) Critically-ill (n=66)Non The cutoff values for positivity in all aPLs except IgM/IgG aPT/PS were set >20 U based on the recommendations of the manufacturer. The cutoff values for positivity in IgM/IgG aPT/PS were set >30 U based on the recommendations by the manufacturer. aβ2GP1, anti-β2-glycoprotein 1 antibodies; aβ2GP1-D1, anti-β2-glycoprotein domain 1 antibodies; aCL, anticardiolipin antibodies; aPS/PT, anti-phosphatidylserine/prothrombin, LA, lupus anticoagulants; N/D, not determined