The Potential Role of IL-6 in Monitoring Coronavirus Disease 2019

Abstract

Background: The outbreak of coronavirus disease 2019 (COVID-19) in Wuhan City, China spreads rapidly since December, 2019. Most patients show mild symptoms, but some of them develop into severe disease. There is currently no specific medication. The purpose of this study is to explore changes of markers in peripheral blood of severe COVID-19 patients, which may be of value in disease monitoring.

Methods: Clinical data of patients with nonsevere and severe type COVID-19 diagnosed by laboratory test in our institution were collected. The relationship between peripheral blood cells and cytokines, clinical manifestation and outcome was analyzed.

Results: A total of 69 severe type COVID-19 patients were included. On admission, the median age of severe cases was 56-year old, with 52.17% of female patient. The most common symptoms were fever (79.72%), coughing (63.77%), shortness of breath (57.97%) and fatigue (50.72%). Diarrhea is less common. The most common comorbidity is hypertension. Upon admission, the proportion of bilateral pulmonary involvement or interstitial pneumonia evidenced by CT imaging in severe cases was 60.87% and 27.54%, respectively. Compared with patients with nonsevere disease, those with severe disease showed lymphocytopenia. Elevated level of lactate dehydrogenase (LDH), C-reactive protein (CRP), ferritin and D-dimer was found in most cases. Two patients (2.9%) needed transfer to the intensive care unit. Baseline immunological parameters and most of the inflammatory parameters were basically within the normal range. However, baseline IL-6 was significantly increased in severe type which is closely related to the maximal body temperature during hospitalization and CT findings. Baseline IL-6 was also significantly related to the increase of baseline level of CRP, LDH, ferritin and D-dimer. The increase of baseline IL-6 level suggests that it may positively correlate with the severity of COVID-19. Among the 30 severe type patient whose level of IL-6 was assessed before and after treatment, significant decrease in IL-6 and improved CT assessment was found in 25 patients after treatment. Whereas the IL-6 level was further increased in 3 cases, which was closely related to the progression of pneumonia. It is suggested that IL-6 may be used as a biomarker for disease monitoring in severe COVID-19 patients.

Conclusion: On admission, the baseline level of IL-6, CRP, LDH and ferritin was closely related to the severity of COVID-19, and the high level of IL-6 was significantly related to the clinical manifestation of severe type patients. The decrease of IL-6 was closely related to treatment effectiveness, while the increase of IL-6 indicated disease progression. Collectively, the dynamic change of IL-6 level can be used as a marker for disease monitoring in patients with severe COVID-19.

Funding Statement: This work was supported by the National Natural Science Foundation of China (No. 81602696 to TL) and Science and Technology Major Project of China (No.2018ZX10302204-002-003).

Declaration of Interests: All authors declare no competing interests.

Ethics Approval Statement: This study was approved by the Research Ethics Committee of Tongji Medical College, Huazhong University of Science and Technology. Written consent was obtained from patients before the enrollment.

Keywords: Coronavirus disease 2019, interleukin-6