The clinical significance of serum chitinase 3-like 1 in hepatitis B-related chronic liver diseases.

Abstract Aim In the present study, we purposed to determine serum chitinase 3‐like 1 (CHI3L1) expression characteristics in chronic liver diseases monoinfected with hepatitis B virus and analyze its diagnostic value in liver fibrosis. Methods A total of 467 chronic hepatitis B (CHB) patients, 312 liver cirrhosis (LC) patients, and 104 hepatocellular carcinoma (HCC) patients at our institution were enrolled, and clinical indicators were analyzed. Results Our data have shown that the expression level of serum CHI3L1 was steadily increased from CHB to LC to HCC (P < .001). Serum CHI3L1 expression levels were positively associated with liver stiffness measurement (LSM), fibrosis‐4 (FIB‐4) index, aspartate aminotransferase‐to‐platelet ratio index (APRI), and HCC stage. The receiver operating characteristic (ROC) curve proved that serum CHI3L1 was superior to other noninvasive methods (LSM, FIB‐4, and APRI) with an area under the ROC curve (AUC) of 0.97 in diagnosing significant fibrosis. Conclusions Serum CHI3L1 harbors significant clinical value in chronic liver diseases infected with hepatitis B virus, especially in the diagnosis of fibrosis.

of Liver Diseases (AASLD) and the Guideline of Prevention and Treatment for CHB from Chinese Society of Hepatology, Chinese Medical Association, proper assessment of liver fibrosis stages is vital to determining the timing of antiviral therapy. 6 Hence, it is very considerable for us to detect the degree of liver fibrosis correctly.
In the past few years, liver biopsy is the gold standard for evaluating the stage of liver fibrosis. 7 Nevertheless, for some reasons, such as invasiveness, poor consistency, high cost, or serious complications, its application is greatly limited, especially in dynamic monitoring disease evolution. 8 In recent years, some noninvasive detection techniques have emerged, such as transient elastography (TE), FibroTest, and ActiTest. However, their accuracy is far from satisfactory. 9 Hence, there is an unmet need to discover novel potential biomarkers to improve the accuracy of fibrosis detection.
Chitinase 3-like 1 (CHI3L1) is a member of the chitinase family, which can combine with chitin but lacks chitinolytic activity. 10 CHI3L1 makes a difference in the process of inflammation and tissue remodeling 11 Recently, CHI3L1 mRNA expression was characterized by tissue specificity, which level was highest in the liver. 12 Johansen et al 13 reported that the expression level of CHI3L1 in serum could evaluate the degree of liver fibrosis. These proofs suggest that CHI3L1 can be promising novel targets for fibrosis diagnosis.
The purposes of this study were to explore the expression feature of serum CHI3L1 in the different stages of patients infected with HBV and to analyze the diagnostic value of CHI3Ll in liver fibrosis combined with the pathological data of liver biopsy. Our results indicate that CHI3L1 could serve as a serum biomarker not only for diagnosing liver fibrosis but also for monitoring the process of chronic liver diseases monoinfected with HBV. Of Sciences. Clinical information was obtained under an institutional review board approved study protocol, and written informed consent was signed from each patient.

| Detection of clinical indicators
All clinical indicators were tested during the same period by standard methods in HwaMei Hospital, University Of Chinese Academy Of Sciences, including blood platelet count, alanine aminotransferase (ALT), aspartate aminotransferase (AST), albumin, bilirubin, prothrombin time (PT), α-fetoprotein (AFP), and liver stiffness measurement (LSM). Blood platelet count was measured by ADVIA 2120i

| Serum CHI3L1 protein level determination
The levels of CHI3L1 in the serum were measured by CHI3L1 ELISA Kit manufactured by Proprium Biotech Co.

| Histological assessment
Among the patients with CHB, 50 cases have received ultrasoundguided liver biopsy. METAVIR scoring system was used to assess the fibrosis stage (F0 = no fibrosis, F1 = portal fibrosis without septa, F2 = portal fibrosis with rare septa, F3 = numerous septa without cirrhosis, F4 = cirrhosis) by two experienced pathologists in blind manner. 15

| Clinical score evaluation
The severity of liver dysfunction was evaluated by Child-Pugh score in the LC group. 16 HCC staging was based on the tumor-node-metastasis (TNM) staging system 17

| Characteristics of enrolled patients
The clinical characteristics of all enrolled patients are shown in Table 1. The characteristics of CHB patients who have received ultrasound-guided liver biopsy are shown in Table 2.

| Different serum levels of CHI3L1 in CHB, LC, and HCC
As shown in Figure 1, the expression levels of CHI3L1 were the highest in the HCC group, the lowest in the CHB group, and the middle in the LC group.

| CHI3L1 expression levels were correlated with Child-Pugh stage in LC patients
We grouped the LC patients according to Child-Pugh score. Among them, 247 cases in Child-Pugh A group, 45 cases in Child-Pugh B group, and 20 cases in Child-Pugh C group. Patients were then divided into good liver function group (Child-Pugh A) and liver TA B L E 2 Characteristics of CHB patients who have been carried out ultrasound-guided liver biopsy (data are mean ± SD) dysfunction group (Child-Pugh B and Child-Pugh C). The expression levels of CHI3L1 in good liver function group were lower than those in liver dysfunction group (Figure 2, P < .001).

| CHI3L1 expression levels were correlated with TNM stage, BCLC stage, and AFP in HCC patients
According to TNM stage or BCLC stage, HCC patients were divided into two groups; details are shown in Table 1. As shown in Figure 3, CHI3L1 expression levels were related to TNM stage (P < .001) and BCLC stage (P < .001). ROC curves were then constructed to assess the diagnostic significance of CHI3L1 in HCC staging. 180.23 ng/ mL of CHI3L1 was taken as the cut-off point to distinguish TNM stageⅠ+Ⅱ from stage Ⅲ+Ⅳ, AUC = 0.707, specificity = 0.661, sensitivity = 0.750; taking 168.59 ng/mL of CHI3L1 as the cut-off point to distinguish BCLC stage A + B from stage C + D, AUC = 0.707, specificity = 0.661, sensitivity = 0.750 (Figure 4). Ninety-seven patients have been tested for AFP in the HCC group. According to a threshold of 20 ng/mL, HCC patients were divided into two groups; details are shown in Table 1. As shown in Figure 5, CHI3L1 expression levels were related to serum AFP levels (P < .05).

| Potential value of CHI3L1, LSM, APRI index, and FIB-4 index as biomarkers for fibrosis diagnosis
There were 50 CHB patients on whom ultrasound-guided liver biopsy has been carried out. Among them, 1 patient was stage

| D ISCUSS I ON
The gene of CHI3L1 is located on human chromosome 1q32.1, which is CHI3L1 is not only a noninvasive marker for assessing liver fibrosis before treatment in CHB patients, but also a potential marker for monitoring liver fibrosis changes during treatment.
In this study, serum levels of CHI3L1 were measured in CHB patients, LC patients, and HCC patients and we studied the stage expression characteristics in different stages of chronic liver diseases related to hepatitis B. As Figure 1 shows, the expression levels of Precision staging of HCC patients is critical for determining treatment options and prognosis. 26 As Figure 3 shows, the serum levels of CHI3L1 in HCC patients with early or moderate stages were lower than those with advanced stages. This study indicated that CHI3L1 could be a potential noninvasive surrogate biomarker for HCC staging. AFP was the most widely used biomarker in HCC for decades. 27 As Figure 5 shows, the serum levels of CHI3L1 in HCC patients with low AFP levels were lower than those with high AFP levels. This suggested that CHI3L1 may have potential relationship with AFP, which needs further research.
In recent years, there are some noninvasive methods for fibrosis diagnosing in liver, such as TE, APRI index, and FIB-4 index. Although TE has many advantages, including simple operation, good repeatability, and high accuracy, successful measurement of TE is restricted by size of the intercostal space, obesity, experience of operators, and the value of LSM is affected by cholestasis and fatty degeneration, hepatic inflammation, among other factors. 28 APRI index and FIB-4 index are ground on clinical and biochemical parameters. 29 Patients can benefit from these two indices, because of their low price, good repeatability, and ease of acceptance. 30 However, the sensitivity and accuracy of these two indices in diagnosing CHB-related fibrosis are not very satisfactory. 31 Correlation analysis in this study revealed that CHI3L1 expression levels were positively related to LSM, APRI index, and FIB-4 index in CHB patients ( Figure 6). According to current guidelines, patients with significant fibrosis (≥F2) are recommended for antiviral therapy. 32 (Figure 7).
In summary, we found that serum CHI3L1 has stage expression feature in different stage liver disease with chronic HBV infection. Despite these, our results indicated that CHI3L1 might be utilized as novel biomarker for evaluating the different levels of liver function and HCC staging. Further research demonstrated that CHI3L1 had positive relationship with noninvasive fibrosis diagnosis methods (LSM, APRI index, FIB-4 index) and could be a feasible marker for diagnosing significant fibrosis with a high degree of accuracy, specificity, and sensitivity. But, there are some limitations in this study. Firstly, the number of CHB patients on whom liver biopsy has been carried out is small; secondly, this is single-center study, and multicenter study is to be encouraged to evaluate external performance; thirdly, the exact mechanism of CHI3L1 in hepatocarcinogenesis needs to be further investigated; and fourthly, the prognostic value of CHI3L1 in liver disease is not discussed in this study.