Role of Plasma Calreticulin in the Prediction of Severity in Septic Patients

Hindawi Disease Markers Volume 2019, Article ID 8792640, 6 pages https://doi.org/10.1155/2019/8792640 Research Article Role of Plasma Calreticulin in the Prediction of Severity in Septic Patients Zhiheng Xu, Yuanyuan Yang, Jianmeng Zhou, Yongbo Huang, Ya Wang, Yu Zhang, Yuan Lan, Jie Liang, Xiaoqing Liu, Nanshan Zhong, Yimin Li , and Pu Mao State Key Laboratory of Respiratory Disease, National Clinical Research Center for Respiratory Disease, Guangzhou Institute of Respiratory Health, First Affiliated Hospital of Guangzhou Medical University, Guangzhou Medical University, Guangzhou 510120, China Correspondence should be addressed to Yimin Li; and Pu Mao; Received 23 February 2019; Revised 29 May 2019; Accepted 21 August 2019; Published 12 September 2019 Academic Editor: Silvia Angeletti Copyright © 2019 Zhiheng Xu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Background. Calreticulin has been identified to play a critical role in innate and adaptive immune responses. However, little is known about the role of calreticulin in sepsis with a characteristic of immune disorder. This study was aimed at investigating whether plasma calreticulin level increases in sepsis and its association with sepsis severity. Methods. This retrospective analysis evaluated sepsis patients who were admitted to the intensive care unit (ICU). Healthy subjects were also included as controls. Plasma samples were collected from the patients within 48 h after ICU admission as well as the healthy subjects. Plasma calreticulin levels were measured via the enzyme-linked immunosorbent assay. Results. In total, 127 sepsis patients and 40 healthy controls were included. Calreticulin was significantly increased in sepsis patients than in healthy controls. Furthermore, the level of plasma calreticulin was significantly higher in nonsurvivors than in survivors. Patients with calreticulin levels > 343 5 pg/ml showed lower cumulative survival than those with levels < 343 5 pg/ml. Conclusion. Calreticulin level was positively correlated with the severity of sepsis. High calreticulin level indicated poor prognosis of sepsis patients. 1. Introduction Sepsis is a clinical syndrome associated with a systemic response to infection and an overexuberant inflammatory response, leading to profound cell and organ injury [1]. Despite improvements in intensive care unit (ICU) care during the last 15 years, sepsis remains a life-threatening condition, with mortality rates of 30%–50% [1, 2]. Both innate and adaptive immune system dysfunction play a crucial role during sepsis [3]. Sepsis could alter the innate and adaptive immune responses through immune suppression and chronic inflammation [4]. Immune cell apoptosis has been implicated to be an important mechanism of sepsis, and this is usually followed by multiorgan failure [5]. Thus, identifying a septic immune-related checkpoint of cell death may provide further insight into the pathophysiology of sepsis; further, these checkpoints may serve as predictors of sepsis severity. Calreticulin is a calcium-binding chaperone that is normally an endoplasmic reticulum-resident protein [6], but it has also been identified to play a role in immunogenic cell death and extracellular functions [7]. Under certain stress conditions, including environmental, drug-induced, and hypoxia, calreticulin may be upregulated to regulate cell survival, death, or repair [7]. A previous study showed that calreticulin levels increase during lipopolysaccharideinduced apoptosis [8]. Calreticulin could be secreted from cells [9] and could bind directly to FasL to inhibit FasLmediated apoptosis of Jurkat T cells [10]. Recent studies showed that calreticulin could be expressed on apoptotic cells and contribute to the phagocytosis of the dying cells [11–13]. In addition, calreticulin at higher concentrations in the plasma and synovial fluid of rheumatoid arthritis patients correlated with disease severity [10, 14]. Thus, calreticulin released into the extracellular space may play an 2 important role in immunogenic cell death and inflammatory diseases, which are the key features of sepsis. However, little is known about the role of calreticulin in sepsis in a clinical context. Thus, this study was aimed at investigating the plasma levels of calreticulin in sepsis patients and the potential correlations between plasma calreticulin levels and sepsis severity. Disease Markers Patients identified by inclusion criteria (n = 167) Patients excluded by exclusion criteria (n = 40) (i) Malignant tumor (n = 27) (ii) Organ transplantation (n = 3) (iii) Autoimmune disease (n = 9) (iv) HIV (n = 1) 2. Methods 2.1. Patients and Ethical Concerns. This study was conducted in the Department of Intensive Care Unit of the First Affiliated Hospital of Guangzhou Medical University, from October 2012 to May 2015. We enrolled consecutive patients who fulfilled the sepsis criteria according to Sepsis-3.0 [1, 15]. The ICU patients were excluded if they underwent organ transplantation, have cancer, autoimmune disease, or human immunodeficiency virus (HIV), or are younger than 18 years. Healthy volunteers were also enrolled from our medical examination center as the control group. The study was approved by the Ethics Review Committee of the First Affiliated Hospital of Guangzhou Medical University (#201311), and written informed consent was obtained from patients or surrogates. 2.2. Study Design. Data on demographic characteristics (age and sex), laboratory test findings (blood count and arterial blood gas), length of ICU stay, and 28-day outcomes were collected from medical records. Disease severity was assessed using the Acute Physiology and Chronic Health Evaluation II (APACHE II) score. The primary endpoint was the 28-day sepsis-related mortality. The secondary aim was the relationship between calreticulin levels and sepsis severity. 2.3. Assay Procedures. Plasma calreticulin levels were measured using the enzyme-linked immunosorbent assay according to the manufacturer’s instruction (Cusabio, CSBE09787h). Plasma was collected within 48 h after ICU admission. Briefly, whole blood (5 mL) was drawn and centrifuged at 1000 rpm for 10 min, and the supernatant was stored at -80°C until use. 2.4. Statistical Analysis. Nonnormally distributed variables were expressed as the median and interquartile range (IQR). The Mann–Whitney U test was performed to compare continuous variables between survivors and nonsurvivors. Correlation was determined via the Spearman rank test. Receiver operating characteristic (ROC) curves were used to select the optimal cutoff value for calreticulin. Kaplan-Meier survival analysis using calreticulin groups as strata was conducted via log-rank tests. A univariate and multivariate Cox proportional hazards regression model was used to identify risk f (...truncated)