Dear Editor,
Due to the hypercoagulable state of COVID-19 severity patients, anticoagulants and antiplatelet aggregation have become a research direction to avoid the development of severe COVID-19.1 As a classic antithrombotic drug, aspirin has also been tried in the treatment of COVID-19. Recently, Jean Philippe Kevorkian et al. published an observational cohort study and found that the treatment effect of oral corticosteroids, aspirin, anticoagulants, colchicine and furosemide in combination was better than that of corticosteroids and low-molecular-weight heparin, proved the potential therapeutic effect of aspirin.2 However, a randomized controlled study reported that although aspirin reduced the incidence of thrombotic events, it cannot reduce mortality within 28 days or the risk of progression to invasive mechanical ventilation or death.3 Therefore, the application value of aspirin in COVID-19 is controversial. A Mata-analysis including 12 studies showed that aspirin could improve the outcome of COVID-19, but the mechanism may be related to its anti-inflammatory effects.4 Mendelian randomization (MR) is a reliable method to analyze the causal effect of exposure on disease by using genetic variation.5 In this study, we explored the exact relationship between aspirin and COVID-19 severity through MR analysis, and explored the intermediary to help clinical treatment.
The GWAS data of 18152 very severe COVID-19 cases and 1145546 controls was downloaded from the COVID-19 Host Genetics Initiative (https://www.covid19hg.org/results/r7/). And the GWAS data of aspirin treatment and cytokines were downloaded from the IEU open GWAS project. When aspirin treatment was the exposure, six non palindrome single nucleotide polymorphisms (SNPs) were selected as tool variables (IVs) after removing linkage disequilibrium (r2 < 0.001, Kb > 10000 and p < 5 × 10 − 8). We removed SNPs associated with outcomes and founders to avoid potential pleiotropic effects by the PhenoScannerV2 database (http://www.phenoscanner.medschl.cam.ac.uk/). We use inverse variance weighted (IVW) as the primary MR analysis method, and MR Egger and weighted media were supplemented. The pleiotropy was tested by MR Egger and MR pleiotropy residual sum and outlier (MR-PRESSO), and heterogeneity was analyzed using Cochran's Q test IVW approach. In addition, we also used "Leave-one-out" sensitivity analysis to demonstrate that the causal effect of exposure on outcome was not affected by individual SNPs. Statistical power calculations for MR were implemented by the mRnd website (https://shiny.cnsgenomics.com/mRnd/).
Our results indicated that aspirin treatment was associated with a lower COVID-19 severity rate (P=0.036; OR=0.112; 95% CI: 0.015-0.872). Besides, in the analysis of cytokine as the outcome, aspirin treatment can reduce the level of IL-1RA in serum (P=0.007; β=- 2.323; 95% CI: -4.024- -0.623). Therefore, we further analyzed the relationship between IL1RA and COVID-19 severity. We change the threshold value of the p-value separately to ensure enough SNPs to maintain the statistical strength (P <5 × 10 – 6). Using the same analytical method, we found that the level of IL1RA was related to the higher COVID-19 severity rate (P=0.015; OR=1.128; 95% CI: 1.023-1.243; Table 1 ). We calculated the F values of IVs and all exposed F values are greater than 10, indicating that the SNPs have strong efficacy (Supplementary Table 1). In addition, we did not find significant heterogeneity and pleiotropy (P>0.05, Supplementary Table 2).
Table 1.
The causal association of exposure with outcome in MR analysis.
| Expoure | Outcome | SNPs | Β (95% CI) |
OR (95% CI) |
P |
|---|---|---|---|---|---|
| Aspirin | COVID-19 severity | 6 | |||
| IVW | -2.184 (-4.230- -0.137) |
0.112 (0.015-0.872) |
0.036 | ||
| MR Egger | 2.084 (-3.884-8.053) |
8.038 (0.021-3142.7) |
0.531 | ||
| Weighted median | -1.636 (-4.355-1.082) |
0.195 (0.013-2.952) |
0.238 | ||
| Aspirin | IL1RA | 7 | |||
| IVW | -2.323 (-4.024- -0.623) |
0.098 (0.018-0.536) |
0.007 | ||
| MR Egger | -4.469 (-9.321-0.384) |
0.011 (0-1.467) |
0.131 | ||
| Weighted median | -1.791 (-3.650-0.068) |
0.167 (0.026-1.070) |
0.059 | ||
| IL1RA | COVID-19 severity | 10 | |||
| IVW | 0.120 (0.023-0.217) |
1.128 (1.023-1.243) |
0.015 | ||
| MR Egger | 0.044 (-0.142-0.229) |
1.045 (0.868-1.258) |
0.655 | ||
| Weighted median | 0.069 (-0.045-0.182) |
1.071 (0.956-1.200) |
0.236 |
To calculate the mediating effect of IL1RA on the protection of COVID-19 by aspirin, we defined the causal effect of aspirin treatment on COVID-19 severity as β1, representing the total effect. The causal effect of aspirin treatment on IL1RA is defined as β2, and the causal effect of IL1RA on COVID-19 severity is defined as β3. β2 ×β3 represented the intermediary effect. β2 ×β3/ β1 represented the percentage of the intermediary effect. We calculated that the intermediary effect was -0.279, accounting for 12.76% of the total effect.
In this study, we found that there was a causality between the aspirin treatment and the reduction of COVID-19 severity, but the mechanism is worth exploring. As a non-steroidal anti-inflammatory drug, aspirin can inhibit cyclooxygenase and reduce the production of prostaglandins, affecting the progress of inflammation.6 IL-1RA is an anti-inflammatory antagonist in the interleukin-1 family, and involves in inhibiting the activity of IL-1. It is usually expressed by inflammatory cells such as monocytes, macrophages and dendritic cells, and its expression is increased in acute inflammation.7 It has been found that the monocytes exposed to aspirin upregulated the expression level of IL-1RA and inhibited the IL-1 pathway in vitro cell experiments.8 We speculate that the direct effect of aspirin treatment was related to the upregulated of IL-1RA expression and the inhibition of inflammatory reaction. However, in the MR analysis, the level of IL1RA represents the overall degree of inflammation of the body. Thus, our analysis showed a causal relationship between the aspirin treatment and the low expression of IL1RA. It may represent that aspirin treatment inhibits the inflammatory reaction.
The expression of various cytokines, including IL1RA, was significantly upregulated in the plasma of COVID-19 severity patients.9 In the acute phase of the disease, inflammatory cells are activated and release many cytokines. The high level of IL-1RA represents a severe inflammatory reaction and cytokine storm. Therefore, there is a causal relationship between the high expression of IL1RA and COVID-19 severity. The clinical deterioration and death of COVID-19 severity patients have been considered related to cytokine storm.10 Therefore, inhibiting cytokine storm may be an important link to avoid the occurrence of COVID-19 severity. In conclusion, our study provides evidence for aspirin treatment to reduce COVID-19 severity and provides a potential mechanism that needs further in-depth analysis.
Data availability statement
The original contributions presented in the study are included in the article/Supplementary Material. Further inquiries can be directed to the corresponding authors.
Author contributions
LXX designed the study; LZY wrote the first draft of the manuscript; WJ, SMJ, and ZY revised the manuscript; HCJ, XDB, and ZYM supervised the entire study.
Funding
This work was supported by National Natural Science Foundation of China (No. 82170654, 82100675), Key Research and Development Program of Heilongjiang Province (No.SC2022ZX06C0015) and Excellent Youth Foundation of the First Affiliated Hospital of Harbin Medical University (2021Y12).
Declaration of Competing Interest
The authors have declared no conflict of interest.
Acknowledgments
We thank the COVID-19 Host Gene Initiative for providing high-quality GWAS data.
Footnotes
Supplementary material associated with this article can be found, in the online version, at doi:10.1016/j.jinf.2023.01.025.
Appendix. Supplementary materials
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Data Availability Statement
The original contributions presented in the study are included in the article/Supplementary Material. Further inquiries can be directed to the corresponding authors.