Comparison of simple tests for the non-invasive diagnosis of clinically silent cirrhosis in chronic hepatitis C

Inflammatory Protein Signatures as Predictive Disease-Specific Markers for Non-Alcoholic Steatohepatitis (NASH)

Non-alcoholic fatty liver disease (NAFLD) is the most prevalent chronic disease worldwide, consisting of a broad spectrum of diseases such as simple steatosis (NAFL), non-alcoholic steatohepatitis (NASH), fibrosis, cirrhosis, and hepatocellular carcinoma. Hepatic inflammation plays a key role in the pathophysiology of NAFLD. Inflammatory mediators such as cytokines and chemokines are considered as contributing factors to NAFLD development and progression. In the present study, we aimed to investigate the inflammatory protein signatures as predictive disease-specific markers for non-alcoholic fatty liver disease (NAFLD). This cross-sectional study included healthy control (n = 64), NAFL (n = 109), and NASH (n = 60) human subjects. Serum concentrations of various cytokines and chemokines were evaluated using sensitive multiplex assays. We used principal component analysis (PCoA) to reveal distinct differences in the levels of cytokines and chemokines between each of the study groups. Further, a random forest classification model was developed to identify the panel of markers that could predict diseases. The protein-protein network analysis was performed to determine the various signaling pathways associated with the disease-specific panel of markers. Serum concentrations of TNF-α, IL-1β, IL-1ra, G-CSF, PDGF-BB, MCP-1, MIP-1a, MIP-1b, RANTES, eotaxin, IL-8 and IP-10 were significantly increased in NASH group as compared to control group. Furthermore, serum concentrations of IL-9 and IL-13 were significantly lower in the NASH group, whereas IL-2 levels were significantly decreased in the NAFL group when compared to the control group. PCoA results demonstrated statistically significant differences in cytokines and chemokines between each of the study groups (PERMANOVA p = 0.001; R2 = 0.102). RANTES, IL-1ra, MIP-1b, IL-2, and G-CSF could differentiate the NAFL group from the controls; G-CSF, IL-1ra, TNF-α, RANTES, and IL-9 could differentiate the NASH group from the controls; and G-CSF, IL-9, IL-13, eotaxin, and TNF- α could differentiate the NASH group from the NAFL group. Our protein-protein network revealed that these markers are involved in cytokine-cytokine receptor interaction, Th1 and Th2 cell differentiation, TNF, chemokine, JAK/STAT, P13K/Akt, TLR, NOD-like receptor, NF-kB, and adipocytokine signaling pathways which might be responsible for disease pathogenesis. Our study findings revealed a set of distinct cytokine and chemokine markers and they might be considered as biomarkers in distinguishing NASH from NAFL. Future multicentre studies with larger sample size are recommended to determine the potential utility of these panels of markers.

The role of noninvasive scoring systems for predicting cardiovascular disease risk in patients with nonalcoholic fatty liver disease: a systematic review and meta-analysis

BACKGROUNDS

Cardiovascular disease (CVD) is suggested as a leading cause of death among patients with nonalcoholic fatty liver disease (NAFLD). The aim of this work was to clarify the role of noninvasive scoring systems (NSSs) in predicting CVD risk among this population.

METHODS

The PubMed, Web of Science, and Cochrane databases were searched until 23 March 2022. Meta-analysis was performed for three most commonly used NSS separately, that is, fibrosis-4 index (FIB-4), NAFLD fibrosis score (NFS), and AST/platelet ratio index (APRI).

RESULTS

Totally, nine studies including 155 382 patients with NAFLD were enrolled. Patients with NAFLD had a higher risk of CVD with increasing FIB-4 score (1.94, 1.52-2.46), the association remained significant after adjustment for age, sex, body mass index, hypertension, and diabetes (2.44, 1.85-3.22). Similarly, a higher risk of CVD was also observed in patients with increasing NFS (2.17, 1.58-2.98) and APRI scores (1.36, 1.04-1.79) in the unadjusted model. However, in the adjusted model, the association was significant only for NFS (3.83, 1.40-10.43), but not for APRI (1.41, 0.79-2.51). Additionally, the increment in CVD risk was most noticeable in subgroup of FIB > 2.67 vs. FIB ≤ 1.3 (6.52, 3.07-13.86) and subgroup of NFS > 0.676 vs. NFS ≤ -1.455 (16.88, 5.68-50.23). All subgroup analyses showed significant associations between FIB-4, NFS, and risk of CVD. Sensitivity analyses did not modify these results.

CONCLUSIONS

FIB-4 and NFS might be useful in identifying those who are at higher risk of CVD among patients with NAFLD. However, APRI was not recommended for this use.

Statistical Machine Learning Approaches to Liver Disease Prediction

Medical diagnoses have important implications for improving patient care, research, and policy. For a medical diagnosis, health professionals use different kinds of pathological methods to make decisions on medical reports in terms of the patients’ medical conditions. Recently, clinicians have been actively engaged in improving medical diagnoses. The use of artificial intelligence and machine learning in combination with clinical findings has further improved disease detection. In the modern era, with the advantage of computers and technologies, one can collect data and visualize many hidden outcomes such as dealing with missing data in medical research. Statistical machine learning algorithms based on specific problems can assist one to make decisions. Machine learning (ML), data-driven algorithms can be utilized to validate existing methods and help researchers to make potential new decisions. The purpose of this study was to extract significant predictors for liver disease from the medical analysis of 615 humans using ML algorithms. Data visualizations were implemented to reveal significant findings such as missing values. Multiple imputations by chained equations (MICEs) were applied to generate missing data points, and principal component analysis (PCA) was used to reduce the dimensionality. Variable importance ranking using the Gini index was implemented to verify significant predictors obtained from the PCA. Training data (ntrain=399) for learning and testing data (ntest=216) in the ML methods were used for predicting classifications. The study compared binary classifier machine learning algorithms (i.e., artificial neural network, random forest (RF), and support vector machine), which were utilized on a published liver disease data set to classify individuals with liver diseases, which will allow health professionals to make a better diagnosis. The synthetic minority oversampling technique was applied to oversample the minority class to regulate overfitting problems. The RF significantly contributed (p<0.001) to a higher accuracy score of 98.14% compared to the other methods. Thus, this suggests that ML methods predict liver disease by incorporating the risk factors, which may improve the inference-based diagnosis of patients.

Activation of heat shock response improves biomarkers of NAFLD in patients with metabolic diseases

Nonalcoholic fatty liver disease (NAFLD) is often accompanied by metabolic disorders such as metabolic syndrome and type 2 diabetes (T2DM). Heat shock response (HSR) is one of the most important homeostatic abilities but is deteriorated by chronic metabolic insults. Heat shock (HS) with an appropriate mild electrical stimulation (MES) activates HSR and improves metabolic abnormalities including insulin resistance, hyperglycemia and inflammation in metabolic disorders. To analyze the effects of HS + MES treatment on NAFLD biomarkers, three cohorts including healthy men (two times/week, n = 10), patients with metabolic syndrome (four times/week, n = 40), and patients with T2DM (n = 100; four times/week (n = 40) and two, four, seven times/week (n = 20 each)) treated with HS + MES were retrospectively analyzed. The healthy subjects showed no significant alterations in NAFLD biomarkers after the treatment. In patients with metabolic syndrome, many of the NAFLD steatosis markers, including fatty liver index, NAFLD-liver fat score, liver/spleen ratio and hepatic steatosis index and NAFLD fibrosis marker, aspartate aminotransferase/alanine aminotransferase (AST/ALT) ratio, were improved upon the treatment. In patients with T2DM, all investigated NAFLD steatosis markers were improved and NAFLD fibrosis markers such as the AST/ALT ratio, fibrosis-4 index and NAFLD-fibrosis score were improved upon the treatment. Thus, HS + MES, a physical intervention, may become a novel treatment strategy for NAFLD as well as metabolic disorders.

Thrombocytopenia in Patients with Chronic Hepatitis C Virus Infection

Thrombocytopenia in patients with chronic hepatitis C virus (HCV) infection is a major problem. The pathophysiology is multifactorial, with auto-immunogenicity, direct bone marrow suppression, hypersplenism, decreased production of thrombopoietin and therapeutic adverse effect all contributing to thrombocytopenia in different measures. The greatest challenge in the care of chronic HCV patients with thrombocytopenia is the difficulty in initiating or maintaining IFN containing anti-viral therapy. Although at present, it is possible to avoid this challenge with the use of the sole Direct Antiviral Agents (DAAs) as the primary treatment modality, thrombocytopenia remains of particular interest, especially in cases of advanced liver disease. The increased risk of bleeding with thrombocytopenia may also impede the initiation and maintenance of different invasive diagnostic and therapeutic procedures. While eradication of HCV infection itself is the most practical strategy for the remission of thrombocytopenia, various pharmacological and non-pharmacological therapeutic options, which vary in their effectiveness and adverse effect profiles, are available. Sustained increase in platelet count is seen with splenectomy and splenic artery embolization, in contrast to only transient rise with platelet transfusion. However, their routine use is limited by complications. Different thrombopoietin analogues have been tried. The use of synthetic thrombopoietins, such as recombinant human TPO and pegylated recombinant human megakaryocyte growth and development factor (PEG-rHuMDGF), has been hampered by the development of neutralizing antibodies. Thrombopoietin-mimetic agents, in particular, eltrombopag and romiplostim, have been shown to be safe and effective for HCV-related thrombocytopenia in various studies, and they increase platelet count without eliciting any immunogenicity Other treatment modalities including newer TPO analogues-AMG-51, PEG-TPOmp and AKR-501, recombinant human IL-11 (rhIL-11, Oprelvekin), recombinant human erythropoietin (rhEPO), danazol and L-carnitine have shown promising early result with improving thrombocytopenia. Thrombocytopenia in chronic HCV infection remain a major problem, however the recent change in DAAs without IFN, as the frontline therapy for HCV, permit to avoid the dilemmas associated with initiating or maintaining IFN based anti-viral therapy.

Quantitative comparison of transient elastography (TE), shear wave elastography (SWE) and liver biopsy results of patients with chronic liver disease

[Purpose] The purpose of this study was to carry out a comparitive analysis of hepatic fibrosis results of the liver hardness of patients with chronic liver disease as measured by elastography (TE), shear wave elastography (SWE), and liver biopsy. [Subjects and Methods] This study was a retrospective analysis of 304 patients who underwent SWE and TE before and after liver biopsy, taken from among patients who had been checked for liver fibrosis by liver biopsy between August 2013 and August 2014. We used receiver operating characteristic (ROC) curve to prove the diagnostic significance of liver stiffness, and then analyzed the sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of SWE and TE, as well as the kappa index through cross-analysis of SWE, TE, and liver biopsy. [Results] For liver hardness, the sensitivity of SWE was 84.39%, the specificity of SWE was 97.92%, the accuracy of SWE was 87.33%, the positive predictive value of SWE was 99.32%, and the negative predictive value of SWE was 63.51%. The sensitivity of TE was 94.80%, the specificity of TE was 77.08%, the accuracy of TE was 90.95%, the positive predictive value of TE was 93.97%, and the negative predictive value of TE was 80.43%. [Conclusion] It is our opinion that SWE and TE are non-invasive methods that are more effective than the invasive methods used for diagnosing liver hardness. Invasive methods cover only a section of liver tissue, and are more likely to cause side effects during biopsy.

Comparisons of noninvasive indices based on daily practice parameters for predicting liver cirrhosis in chronic hepatitis B and hepatitis C patients in hospital and community populations

Several noninvasive indices have been proposed for predicting liver cirrhosis (LC), particularly in chronic hepatitis C (CHC). In this study, noninvasive indices for predicting LC and hepatocellular carcinoma (HCC) were compared. A total of 119 chronic hepatitis B (CHB) patients and 240 CHC patients were evaluated in a hospital-based setting using various predictors for pathologic LC such as aspartate aminotransferase/alanine aminotransferase (AST/ALT) ratio (AAR), AAR-to-platelet ratio index (AARPRI), AST-to-platelet ratio index (APRI), age-platelet (AP) index, and platelet counts. In addition, these indices were used to predict LC [based on ultrasound (US)] in a community-based population of 201 patients with endemic hepatitis C virus (HCV). These indices were evaluated for their ability to predict HCC in CHB and CHC patients (n = 200). In CHB patients, the diagnostic performance of all indices was inadequate for predicting LC (areas under receiver operating characteristic curves < 0.7). Thrombocytopenia consistently demonstrated comparable accuracy to AARPRI ≥ 0.7 in CHB and AP index ≥ 7.0 in CHC patients. The best cut-off values for APRI, AARPRI, and AP index in predicting LC in CHC were 1.3, 0.8, and 7.0, respectively. The best cut-off values for APRI, AARPRI, and AP index in predicting LC (based on US) were 1.0, 1.2, and 8.0, respectively, in a HCV endemic community. An AAR > 1.4 might be a useful tool to identify candidates at high risk for HCC. In conclusion, platelet count was both consistent and accurate in predicting LC. An AAR > 1.4 is proposed as a possible surrogate marker for identifying patients at high risk for developing HCC.

Prevalence of thrombocytopenia among patients with chronic hepatitis C: a systematic review

Thrombocytopenia (TCP) is a haematological condition known to occur in chronically infected hepatitis C (HCV) patients and may interfere with diagnostic procedures, such as liver biopsy, because of risk of bleeding. It may also exclude patients from effective antiviral treatment. We conducted a systematic literature review of articles and conference abstracts, to assess the prevalence of TCP among those with HCV and to describe demographics, liver disease stage and treatment characteristics of these patients. Studies of individuals with confirmed chronic HCV infection were included in the review if the study had a clear definition of thrombocytopenia and a sample size of at least 50 subjects. The final selection included 27 studies (21 articles and six abstracts). The definitions of thrombocytopenia varied between studies and were based either on platelet counts, with threshold levels ranging between ≤ 100 × 10(9) and ≤ 180 × 10(9) /L, or on criteria set in haematological guidelines. The prevalence of TCP ranged from 0.16% to 45.4% and more than half of the studies reported a TCP prevalence of 24% or more. Because of the different TCP definitions, heterogeneity in study design and insufficient data on study characteristics such as age, gender, HCV treatment rates and disease severity an overall summary estimate of TCP prevalence among patients with HCV was not feasible. However, the relatively large prevalence in the majority of the studies suggests that there may be a substantial number of HCV patients at risk of bleeding complications and reduced likelihood of successful HCV antiviral treatment.

Validation of P2/MS for reflecting hepatic fibrosis in patients with hepatocellular carcinoma

BACKGROUND/AIMS

P2/MS is known as a simple, accurate, and noninvasive marker for determination of the degree of hepatic fibrosis in patients with viral hepatitis. We aimed to validate P2/MS in patients with HCC.

METHODS

Consecutive HCC patients who underwent surgical resection between June 2007 and March 2009 at Seoul National University Hospital were enrolled. Fibrosis stage was reviewed and assessed according to METAVIR scoring. P2/MS values [platelet count (10(9)/L)](2)/[monocyte fraction (%)(x)segmented neutrophil fraction (%)] and other noninvasive fibrosis scoring systems were calculated.

RESULTS

A total of 171 patients were included; seven patients with METAVIR F1, 31 with F2, 41 with F3, and 92 with F4. The area under the receiver-operating characteristic curve of P2/MS was 0.804 [95% confidence interval (CI), 0.681~0.927] for detection of significant fibrosis (F2-F4) and 0.769 (95% CI, 0.698~0.839) for detection of histological cirrhosis (F4). At a value < 62, P2/MS detected significant fibrosis with a specificity of 85.7% (95% CI, 42.0~99.2) and a positive likelihood ratio of 4.268 (95% CI, 0.692~26.309); and at a value > 115, P2/MS ruled out significant fibrosis with a sensitivity of 90.2% (95% CI, 84.4~94.1) and a negative likelihood ratio of 0.34 (95% CI, 0.106~0.095). P2/MS had a superior efficacy for detection of hepatic fibrosis in patients with HCC compared to the other noninvasive panels.

CONCLUSIONS

P2/MS can accurately detect fibrosis in patients with HCC. Thus, P2/MS might be utilized as a noninvasive index reflecting the degree of hepatic fibrosis in HCC patients.

Comparison of noninvasive markers of fibrosis in patients with nonalcoholic fatty liver disease

BACKGROUND & AIMS

There is a need for a reliable and inexpensive noninvasive marker of hepatic fibrosis in patients with nonalcoholic fatty liver disease (NAFLD). We compared the performance of the FIB4 index (based on age, aspartate aminotransferase [AST] and alanine aminotransferase [ALT] levels, and platelet counts) with 6 other non-invasive markers of fibrosis in patients with NAFLD.

METHODS

Using a nation-wide database of 541 adults with NAFLD, jackknife-validated areas under receiver operating characteristic curves (AUROC) of FIB4 and 7 other markers were compared. The sensitivity at 90% specificity, 80% positive predictive value, and 90% negative predictive values were determined along with cutoffs for advanced fibrosis.

RESULTS

The median FIB4 score was 1.11 (interquartile range = 0.74-1.67). The jackknife-validated AUROC for FIB4 was 0.802 (95% confidence interval [CI], 0.758-0.847), which was higher than that of the NAFLD fibrosis score (0.768; 95% CI, 0.720-0.816; P = .09), Goteburg University Cirrhosis Index (0.743; 95% CI, 0.695-0.791; P < .01), AST:ALT ratio (0.742; 95% CI, 0.690-0.794; P < .015), AST:platelet ratio index (0.730; 95% CI, 0.681-0.779; P < .001), AST:platelet ratio (0.720; 95% CI, 0.669-0.770; P < .001), body mass index, AST:ALT, diabetes (BARD) score (0.70; P < .001), or cirrhosis discriminant score (0.666; 95% CI, 0.614-0.718; P < .001). For a fixed specificity of 90% (FIB4 = 1.93), the sensitivity in identifying advanced fibrosis was only 50% (95% CI, 46-55). A FIB4 > or = 2.67 had an 80% positive predictive value and a FIB4 index < or = 1.30 had a 90% negative predictive value.

CONCLUSIONS

The FIB4 index is superior to 7 other noninvasive markers of fibrosis in patients with NAFLD; however its performance characteristics highlight the need for even better noninvasive markers.

Systematic review: non-invasive methods of fibrosis analysis in chronic hepatitis C

BACKGROUND

Accurate determination of the presence and degree of liver fibrosis is essential for prognosis and for planning treatment of patients with chronic hepatitis C virus (HCV). Non-invasive methods of assessing fibrosis have been developed to reduce the need for biopsy.

AIM

To perform a review of these non-invasive measures and their ability to replace biopsy for assessing hepatic fibrosis in patients with chronic HCV.

METHODS

A systematic review of PUBMED and EMBASE was performed through 2008 using the following search terms: HCV, liver, elastography, hepatitis, Fibroscan, SPECT, noninvasive liver fibrosis, ultrasonography, Doppler, MRI, Fibrotest, Fibrosure, Actitest, APRI, Forns and breath tests, alone or in combination.

RESULTS

We identified 151 studies: 87 using biochemical, 57 imaging and seven breath tests either alone or in combination.

CONCLUSIONS

Great strides are being made in the development of accurate non-invasive methods for determination of fibrosis. Although no single non-invasive test or model developed to date can match that information obtained from actual histology (i.e. inflammation, fibrosis, steatosis), combinations of two modalities of non-invasive methods can reliably differentiate between minimal and significant fibrosis, and thereby avoid liver biopsy in a significant percentage of patients.

Prediction of asymptomatic cirrhosis in chronic hepatitis C patients: accuracy of artificial neural networks compared with logistic regression models

OBJECTIVE

Models based on logistic regression analysis are proposed as noninvasive tools to predict cirrhosis in chronic hepatitis C (CHC) patients. However, none showed to be sufficiently accurate to replace liver biopsy. Artificial neural networks (ANNs), providing a prediction based on nonlinear algorithms, can improve the diagnosis of cirrhosis, a syndrome characterized by complex, nonlinear biological alterations. We compared ANNs with two logistic regression analysis-based models in predicting CHC histologically proven cirrhosis.

METHODS

Liver biopsy was obtained in CHC patients of two different cohorts (an internal cohort including 244 patients and an external cohort including 220 patients). One hundred and forty-four patients from the internal cohort served as a training set to construct ANNs and a logistic regression model (LOGIT). These two models and the aspartate aminotransferase-to-platelet ratio index (APRI) were tested in the remaining 100 patients (internal validation set) and in the external cohort (external validation set). Diagnostic performances were evaluated by standard indices of accuracy.

RESULTS

In the internal validation set, ANNs, LOGIT, and APRI showed similar discrimination powers (0.88, 0.87, and 0.87 respectively). However, ANNs showed the best positive predictive value (0.86 vs. 0.67 and 0.56) and positive likelihood ratio (40.2 vs. 13.4 and 8.4). In the external validation set, the discrimination power of ANNs (0.76) was significantly higher than those of LOGIT (0.67) and APRI (0.67).

CONCLUSION

Compared to conventional models, ANNs performance in predicting CHC cirrhosis is slightly better and more reproducible.

[Liver stiffness measurement for the diagnosis of hepatic fibrosis in patients with chronic viral hepatitis]

BACKGROUND AND AIMS

FibroScan is a new medical device that noninvasively measures liver stiffness. The aim of this study was to assess the accuracy of the liver stiffness measurement by FibroScan for making the diagnosis of liver fibrosis in patients with chronic viral hepatitis.

METHODS

We studied 103 patients with chronic viral hepatitis B or C and they underwent FibroScan and liver biopsy between October 2005 and August 2006. Liver fibrosis was staged on a 0-4 scale according to the Korean Society of Pathologists Scoring System. The diagnostic accuracy was assessed by analysis of the receiver operator characteristics (ROC).

RESULTS

The liver stiffness was 3.5-57.1 kPa (mean: 11.8, SD: 8.9). The mean value of liver stiffness in each fibrosis stage group (F1, F2, F3 and F4) was 5.8+/-1.8 kPa, 11.3+/-6.8 kPa, 11.8+/-6.0 kPa and 23.4+/-16.5 kPa, respectively. Liver stiffness measured by FibroScan showed reliable correlation with the liver fibrosis stage as confirmed by liver biopsy (r=0.56, p<0.001). The AUROC (95% CI) of > or = F2, > or = F3 and F4 was 0.93 (0.86-0.99), 0.72 (0.62-0.82) and 0.80 (0.67-0.92), respectively. The sensitivity and specificity of 7.5 kPa, which was the cutoff value for > or = F2, was 84% and 90%, respectively.

CONCLUSIONS

FibroScan is a reliable method for the diagnosis of significant fibrosis (> or =F2) and cirrhosis in patients with chronic liver disease. The liver stiffness measurement by FibroScan showed good diagnostic performance for significant fibrosis.

A study of the effect of splenectomy on hepatic functional reserve and structural damage in patients with chronic hepatitis C virus infection by non-invasive serum markers. A prospective study

Several beneficial effects of splenectomy on the liver integrity have been recently reported by both experimental and clinical studies. However, the effects of splenectomy on hepatic functional reserve and structural damage in patients with chronic hepatitis C (CHC) were not studied by objective evidence. The aim of this study was to assess the effect of splenectomy on hepatic functional reserve and structural damage in patients with CHC by non-invasive serum markers. The study involved 22 patients with histopathological diagnosis of CHC undergoing splenectomy for treatment of associated hypersplenism. The hepatic functional reserve and structural damage markers were assessed before and after splenectomy surgery on the 2nd and 60th postoperative days by aspartate aminotransferase to alanine aminotransferase (AST/ALT ratio), AST to platelet ratio index (APRI) and serum levels of gamma-glutamyl transferase (GGT), hyaluronic acid (HA), type IV collagen (CIV) and tissue inhibitor of metalloproteinase-1 (TIMP-1). After splenectomy, the levels of serum HA showed a significant decrease in relation to the preoperative values both in PO-1 (mean pre-splenectomy: 272+/-88.6 versus 185+/-77.4 ng/ml; P=0.01) and PO-2 (169+/-58.1 ng/ml; 0.017). The levels of type IV collagen showed a significant decrease in relation to the preoperative values both in PO-1 (mean pre-splenectomy: 208+/-134 versus 125+/-100 ng/ml; P=0.01) and PO-2 (121+/-74.7 ng/ml; P=0.02). Serum levels of TIMP-1 also showed a significant decrease in relation to the preoperative values both in PO-1 (mean pre-splenectomy: 764+/-571 versus 261+/-195 ng/ml; P=0.006) and PO-2 (149+/-110.1 ng/ml; P=0.004). There was no significant difference between PO-1 and PO-2 mean values for each of those serum markers. This study found that splenectomy induced a reduction of biochemical markers of liver functional reserve and fibrosis in patients with chronic hepatitis C which reflect a change in the processes involved in of liver fibrosis. However, it cannot be concluded whether this reflects a change in the rate of its progression or a prevention of further fibrosis.