Biomarker use in ARDS resulting from COVID-19 infection

There is renewed interest in the use of immunomodulator therapies in patients with acute hypoxemic respiratory failure.

Multiple investigations during the course of the COVID-19 pandemic, including the large RECOVERY and CoDEX trials, demonstrated that dexamethasone administration improved mortality in patients with severe COVID-19.^1,2 Beyond COVID-19, studies have also shown corticosteroid therapy improves clinical outcomes in patients with severe community-acquired pneumonia.³ However, the overwhelming majority of studies identifying plasma biomarkers that are associated with clinical outcomes in severe lung injury predate the routine use of corticosteroids.⁴ Two investigators at Massachusetts General Hospital, Jehan W. Alladina, MD, and George A. Alba, MD, performed a study to assess whether plasma biomarkers previously associated with clinical outcomes in ARDS maintained their predictive value in the setting of widespread immunomodulator therapy in the ICU. Drs. Alladina and Alba are physician-scientists and codirectors of the Program for Advancing Critical Care Translational Science at Massachusetts General Hospital in Boston.

In a study published in CHEST^® Critical Care earlier this year, they prospectively enrolled patients with ARDS due to confirmed SARS-CoV-2 infection during the second wave of the COVID-19 pandemic from December 31, 2020, to March 31, 2021, at Massachusetts General Hospital.⁵ Plasma samples were collected within 24 hours of intubation for mechanical ventilation for protein analysis in 69 patients. Baseline demographics included a mean age of 62 plus or minus 15 years and a BMI of 31 plus or minus 8, and 45% were female. The median PaO₂ to FiO₂ ratio was 174 mm Hg, consistent with moderate ARDS, and the median duration of ventilation was 17 days. The patients had a median modified sequential organ failure assessment score of 8.5, and in-hospital mortality was 44% by 60 days. Notably, all patients in this cohort received steroids during their ICU stay.

^CHEST

Dr. George A. Alba

Interestingly, the study investigators found no association between clinical outcomes and circulating proteins implicated in inflammation (eg, interleukin [IL]-6, IL-8), epithelial injury (eg, soluble receptor for advanced glycation end products, surfactant protein D), or coagulation (eg, D-dimer, tissue factor). However, four endothelial biomarkers—von Willebrand factor A2 domain; angiopoietin-2; syndecan-1; and neural precursor cell expressed, developmentally downregulated 9 (NEDD9)—were associated with 60-day mortality after adjusting for age, sex, and severity of illness. A sensitivity analysis, in which patients treated with the IL-6 inhibitor tocilizumab (n=4) were excluded, showed similar results.

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Dr. Jehan A. Alladina

Of the endothelial proteins, NEDD9 demonstrated the greatest effect size in its association with mortality in patients with ARDS due to COVID-19 who were treated with immunomodulators. NEDD9 is a scaffolding protein highly expressed in the pulmonary vascular endothelium, but its role in ARDS is not well known. In pulmonary vascular disease, plasma levels are associated with adverse pulmonary hemodynamics and clinical outcomes. Pulmonary artery endothelial NEDD9 is upregulated by cellular hypoxia and can mediate platelet-endothelial adhesion by interacting with P-selectin on the surface of activated platelets.⁶ Additionally, there is evidence of increased pulmonary endothelial NEDD9 expression and colocalization with fibrin within pulmonary arteries in lung tissue of patients who died from ARDS due to COVID-19.⁷ Thus, NEDD9 may be an important mediator of pulmonary vascular dysfunction observed in ARDS and could be a novel biomarker for patient subphenotyping and prognostication of clinical outcomes.

In summary, in a cohort of patients with COVID-19 ARDS uniformly treated with corticosteroids, plasma biomarkers of inflammation, coagulation, and epithelial injury were not associated with clinical outcomes, but endothelial biomarkers remained prognostic. It is biologically plausible that immunomodulators could attenuate the association between inflammatory biomarkers and patient outcomes. The findings of this study highlight the association of endothelial biomarkers with clinical outcomes in patients with COVID-19 ARDS treated with immunomodulators and warrant prospective validation, especially with the increasing evidence-based use of antiinflammatory therapy in acute lung injury. However, there are several important limitations to consider, including a small sample size from a single institution that precludes any definitive conclusions regarding any negative associations. Moreover, the single time point studied (the day of initiation of mechanical ventilation) and absence of a comparator group do not allow a comprehensive evaluation of the impact of antiinflammatory therapies across the trajectory of disease. Whether the findings are generalizable to all patients with ARDS treated with immunomodulators also remains unknown.

Overall, these data suggest that circulating signatures previously associated with ARDS, particularly those related to systemic inflammation, may have limited prognostic utility in the era of increasing immunomodulator use in critical illness. A deeper understanding of the pathobiology of ARDS, including the complex interplay with systemic immunomodulation, is needed to identify prognostic biomarkers and targeted therapies that improve patient outcomes.

Both authors work in the Division of Pulmonary and Critical Care Medicine, Massachusetts General Hospital, Harvard Medical School, in Boston.

References

1. Horby P, Lim WS, Emberson JR, et al; RECOVERY Collaborative Group. Dexamethasone in hospitalized patients with Covid-19. N Engl J Med. 2021;384(8):693-704.

2. Tomazini BM, Maia IS, Cavalcanti AB, et al. Effect of dexamethasone on days alive and ventilator-free in patients with moderate or severe acute respiratory distress syndrome and COVID-19. JAMA. 2020;324(13):1-11.

3. Dequin P-F, Meziani F, Quenot J-P, et al. Hydrocortisone in severe community-acquired pneumonia. N Engl J Med. 2023;388(21):1931-1941.

4. Del Valle DM, Kim-Schulze S, Huang H-H, et al. An inflammatory cytokine signature predicts COVID-19 severity and survival. Nat Med. 2020;26(10):1636-1643.

5. Alladina JW, Giacona FL, Haring AM, et al. Circulating biomarkers of endothelial dysfunction associated with ventilatory ratio and mortality in ARDS resulting from SARS-CoV-2 infection treated with antiinflammatory therapies. CHEST Crit Care. 2024;2(2):100054.

6. Alba GA, Samokhin AO, Wang R-S, et al. NEDD9 is a novel and modifiable mediator of platelet-endothelial adhesion in the pulmonary circulation. Am J Respir Crit Care Med. 2021;203(12):1533-1545.

7. Alba GA, Samokhin AO, Wang R-S, et al. Pulmonary endothelial NEDD9 and the prothrombotic pathophenotype of acute respiratory distress syndrome due to SARS‐CoV‐2 infection. Pulm Circ. 2022;12(2):e12071.