key: cord-0814424-a42d3w0c
authors: Wang, Wenjun; Liu, Xiaoqing; Wu, Sipei; Chen, Sibei; Li, Yimin; Nong, Lingbo; Lie, Puyi; Huang, Liyan; Cheng, Linling; Lin, Yongping; He, Jianxing
title: The Definition and Risks of Cytokine Release Syndrome in 11 COVID-19-Affected Critically Ill Patients with Pneumonia: Analysis of Disease Characteristics
date: 2020-06-30
journal: J Infect Dis
DOI: 10.1093/infdis/jiaa387
sha: 19571b359297e610dee6f2bc6be903f14757fa1b
doc_id: 814424
cord_uid: a42d3w0c

Corona Virus Disease 2019(COVID-19)-affected patients with severe immune abnormalities have a risk of cytokine release syndrome. The definition, prevention, and treatment of symptoms of cytokine release syndrome in critically ill patients with COVID-19 are important problems. This was a single-center case series of 11 COVID-19 patients with acute respiratory distress syndrome (ARDS) from The First Affiliated Hospital of Guangzhou Medical University in China from January 26, 2020 to February 18, 2020. The termination date of follow-up was February 19, 2020. In this single-center analysis of 11 critically ill patients with COVID-19, 8 patients were determined to have characteristics of cytokine release syndrome (CRS), including pulmonary inflammation, fever, and dysfunction of non-pulmonary organs; an increase of- Interleukin-6 (IL-6) in peripheral blood was the highest risk factor and an early indicator of CRS in COVID-19.

In December 2019, a novel coronavirus, which was named severe acute respiratory syndrome coronavirus 2 (COVID-19) by the International Committee on Taxonomy of Viruses, was discovered in Wuhan, Hubei province, China [1] [2] [3] . The disease spread rapidly to all provinces of China outside of Wuhan [4, 5] .

By February 17, 2020 , there were 70,636 confirmed cases and 1,772 deaths in China [6] . Some of the COVID-19-affected critically ill patients with pneumonia had serious symptoms with no specific drug treatment indicated. Severe inflammatory reaction and respiratory distress syndrome can lead to rapid progression of the disease and cause death. A guideline, "Diagnosis and treatment of novel coronavirus pneumonia (trial version 5)", was first published in China on February 3 [7] . It suggested that immune factors needed examining in the therapy of COVID-19-affected patients with pneumonia. The release of inflammatory immune cytokines could increase the inflammation of the lung and risk the occurrence of acute respiratory distress syndrome (ARDS) [8] . ARDS may lead to hypoxia and lung injury, causing the further release of inflammatory factors by multiple mechanisms [9] [10] [11] . Therefore, an excessive release of inflammatory factors may promote ARDS in COVID-19 patients with pneumonia.

Critically ill COVID-19-affected patients with pneumonia suffer from fever, pulmonary inflammation, respiratory distress, and other clinical signs. In published data, the proportion of patients requiring intensive care unit (ICU) treatment is 26.1% [12] . The average age of patients in the ICU is higher than A c c e p t e d M a n u s c r i p t that of non-ICU patients [12] . In addition, the incidence of acute heart injury and respiratory distress in ICU patients with COVID-19 is much higher than that in the general population [13] . Serious pulmonary inflammation is common in critically ill COVID-19-affected patients with pneumonia [14] . The large area of infection and inflammatory reaction causes many immunologic problems, such as cytokine release syndrome (CRS), which can rapidly lead to deterioration and death [15, 16] . In this study, after analysis of the clinical diagnosis and immunological characteristics of 11 critically ill COVID-19-affected patients with ARDS, we diagnosed eight (8/11, 72 .7%) patients with features of CRS.

Therefore, we defined this phenomenon as COVID-19 infection-related CRS.

Our results demonstrated that IL-6 was an early indicator of CRS in COVID-19associated pneumonia, and it is suggested that improving ventilation and controlling the area of pulmonary inflammation may be an effective method to treat COVID-19-affected pneumonia patients with CRS and ARDS. Our research provides experimental support and experience useful for the treatment of critically ill COVID-19-affected patients with pneumonia.

This was a single-center study. The patients enrolled in this study were confirmed to have severe or critical COVID-19-associated pneumonia. The inclusion criteria were defined by the "Pneumonia diagnosis and treatment plan for new coronavirus infection (trial version 5)" issued by the National Health A c c e p t e d M a n u s c r i p t Commission on February 5, 2020 (hereinafter referred to as "Diagnosis and treatment plan version 5") [7] . Enrollment began on January 26, 2020. We obtained verbal consent from each patient. According to the monitoring results (the date of transfer out of the ICU), the final follow-up date was February 18, 2020 for all COVID-19-affected patients participating in this study. This series of cases was approved by the ethics committee of the First Affiliated Hospital of Guangzhou Medical University, China.

The team of the First Affiliated Hospital of Guangzhou Medical University conducted an analysis of each patient's medical records, including:

a.) Basic information on the patient: name, gender, age, hospitalization number, diagnosis, date of admission, condition, laboratory examination results, chest CT scan, nursing care, and treatments (i.e. antiviral treatment, corticosteroid treatment, and respiratory support). The records were taken by a team of trained doctors, and the data were obtained from electronic medical records. b. Data generated by bedside monitors: heart rate, respiration, invasive/noninvasive blood pressure, blood oxygen saturation, hemodynamic monitoring.

c. Medical order execution information: administration times for all medicines, drug name, dose, concentration, route, automatically generated quantity in and out. These data were automatically collected by the ICU clinical information system. 

This was a single-center case series and no patients were involved directly in A c c e p t e d M a n u s c r i p t the study design, setting the research questions, or the outcome measures. No patients were asked to advise on interpretation or writing up of the results.

All 11 COVID-19-affected critically ill patients with pneumonia were admitted to the ICU; 10 (90.9%) of them were male. The median age was 58 years (IQR, 49-72 years). The median time from first symptoms to respiratory distress was 10 days (IQR, 7-13 days). All patients had fever: the highest fever was 40°C, and the median temperature was 38.5°C (IQR, 38-39.6°C). Four (36.4%) patients had muscle soreness in the early stage of fever, and nine (81.8%) had dry cough in the early stage of the disease. All patients had symptoms of hypoxia when they were admitted to the ICU. Among them, five (45.5%) patients had a history of cardio-cerebrovascular disease, and four (36.4%) patients had a history of diabetes (type II diabetes). All the patients had symptoms of low oxygen saturation and metabolic acidosis (Table 1) . After entering the ICU, all the patients had at least one or more manifestations of organ dysfunction or even failure. These included nine patients with cardiac dysfunction, eight with renal dysfunction, six with liver dysfunction and coagulation dysfunction, five with coagulant function abnormality, and four with multi-organ failure syndrome. Ten patients were treated with steroids and all patients had antiviral and anti-infective therapy ( Table 2 and Table 3) . (Table   3 and Table 4 ). None of the patients had a known prior history of immune diseases. The level of IL-6 in three of the patients recovered to normal after treatment of the infection, and CT imaging showed that the pulmonary shadows had disappeared. These three patients had no evidence of extrapulmonary organ injury or blood coagulation dysfunction, and two of them were transferred out of the ICU. Eight of the 11 patients showed sufficient evidence of CRS features (Table 3 and Figure 1 ). After treatment, the levels of CD4, CD8, and NK cells were all recovered. In addition, IL-6 and IFN-γ were decreased. At the same time, the organ function of the patients improved (Table 3 and (Table 4 and Figure 2A，2B and 2C). However, three patients (patients 02#, 03# and 07#) were in a stable condition after ICU treatment at the beginning, and their IL-6 levels showed a rapid increase (increased by 7.2 to 9.2 times) in one or two days (sFigure 2A and 2D); the absolute number of CD4 and CD8 cells decreased one day later than the increase of IL-6 in peripheral blood (sFigure 2B and 2C). The PaO2 and PaO2/FiO2 were decreased within one day after the rise of IL-6 (sFigure 2D and 2E). The bedside chest radiography results showed disease progression. These cases indicate that IL-6 was an early indicator of CRS in COVID-19-associated pneumonia.

A c c e p t e d M a n u s c r i p t

Serious pulmonary inflammation is a common symptom in critically ill COVID-19-affected patients with pneumonia [13] . The large area of infection and inflammatory reaction may cause CRS [14, 15] . In our study, according to the distribution of patchy shadows or ground glass opacity in the chest CT images, we divided the patients into groups with < 50% and ≥ 50% (sFigure 2G). The numbers of CD8, CD4, and NK cells in the peripheral blood were higher in the ＜ 50% group than in the ≥ 50% group ( Figure 3A, sFigure2H and sFigure2I ).

In addition, the level of IL-6 in the peripheral blood was lower in the patients with an area of inflammation ≥50 than in those with and area of < 50% on CT imaging ( Figure 3B ).

This was a single-center study of 11 critically ill COVID-19 patients admitted to the ICU with persistent fever and ARDS. In addition to routine laboratory tests Lung injury has a potential risk of CRS [18] . Cytokine release is common in immunotherapy, especially in cellular immunotherapy. The reasons for the A c c e p t e d M a n u s c r i p t occurrence of CRS are unclear, although the main mechanism is that inflammatory cells, such as effector T cells and macrophages, accumulate rapidly from peripheral blood in response to chemokines and release a large number of cytokines into the blood when they kill tumor cells, viruses, or bacteria [19] . The disease is characterized by a marked increase in characteristic cytokines (such as IL-6), persistent fever, and organ and tissue damage [20] . The rapid chain reaction caused by CRS usually causes rapid organ immune-related injury and acute functional failure [21] . In our study, we found that the patients with severe pneumonia also showed an increase of IL-6, and the level of IL-6 was associated with the area of pulmonary inflammation.

It has been suggested that an increase of IL-6 is caused by severe pneumonia and the immune reaction in the lung. However, the decrease of IL-6 in patients with severe pneumonia was earlier than the resolution of the area of pulmonary shadowing. Considering published results, our findings indicate that IL-6 may act as a prognostic factor in COVID-19-affected patients with severe pneumonia.

We analyzed the clinical and immunological characteristics of 11 COVID-19affected patients with severe pneumonia. We found that: Patients with severe pneumonia had different degrees of fever; peripheral blood CD4, CD8, NK, and other immune T cells were decreased; CD4/CD8 increased significantly, and IL-6 increased significantly; multiple organ injuries were present; and coagulation dysfunction occurred. The concentration of IL-6 and the number of A c c e p t e d M a n u s c r i p t CD4, CD8, and NK immune cells in the peripheral blood can be significantly reduced by improving ventilation, lowering body temperature, and using antiinflammatory treatment and other supportive treatment. The function of organs and tissues will be improved, which shows the importance of cytokines. COVID-19-affected patients with severe pneumonia have symptoms and manifestations similar to those of CRS. Therefore, we define this phenomenon as COVID-19-related CRS, and the characteristics include: ① substantial increase of IL-6 cytokine in peripheral blood; ② continuous fever; and ③ organ and tissue damage caused by the cytokine related immune reaction, and coagulation dysfunction. We also found that eight of 11 (72.7%) critically ill patients in our study had characteristics consistent with CRS.

Large-scale lung injury caused by viral pneumonia is the inducing factor for COVID-19-related CRS. Given that large-scale lung injury is a typical feature of critical patients, COVID-19-related CRS may be a common phenomenon in critically ill patients. We found that a large area of lung injury (≥ 50%) with a decrease of CD4 and CD8 cells (< 50% minimum normal range) and an increase of IL-6 in peripheral blood were the most important risk factors for CRS.

With COVID-19-associated pneumonia in critically ill patients, the change of IL-6 levels occurred one or two days earlier than the decreases in the absolute number of CD4 and CD8 cells in peripheral blood. This indicates that IL-6 may work as an early indicator of CRS in COVID-19-related pneumonia.

This study has several limitations. First, we only studied 11 critical patients in a A c c e p t e d M a n u s c r i p t single center and we were unable to conduct a group comparison study.

Additional data from critical patients elsewhere in China would be useful.

Second, due to the strong infectivity of the virus, we were not able to construct an animal model of COVID-19-related pneumonia. A validated model could help clarify the molecular mechanism of CRS caused by viral pneumonia. Third, we have not completed the clinical experiment on the treatment of COVID-19associated pneumonia with IL-6 monoclonal antibody.

We identified and defined CRS in 11 critically ill patients with COVID-19-related pneumonia. IL-6 was an early indicator of CRS in COVID-19 pneumonia. We also found that reducing injury to the lung is a useful method to prevent and improve pneumonia-related CRS in critically ill patients with COVID-19.

For Research articles only A c c e p t e d M a n u s c r i p t Transparency: The lead authors and manuscript's guarantor affirm that the manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned have been explained.

Dissemination to participants and related patient and public communities: No study participants were involved in the preparation of this article. The results of the article will be summarized in media press releases from the Guangzhou Medical University and presented at relevant conferences. M a n u s c r i p t When the shadowed area was less than 50%, the absolute counts of CD8+ (P M a n u s c r i p t Signs and symptoms at admission 

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