Tricking an ancient immune function to eradicate hepatocellular carcinoma

Artificial intelligence/neural network system that accurately diagnoses hepatocellular carcinoma in nonalcoholic steatohepatitis

BACKGROUND AND AIM

The aim of this study was to develop a novel noninvasive test using an artificial intelligence/neural network system (called HCC-Scope) to diagnose early-stage hepatocellular carcinoma (HCC) on the background of nonalcoholic steatohepatitis (NASH).

METHODS

In total, 175 patients with histologically proven nonalcoholic fatty liver disease and 55 patients with NASH-HCC were enrolled for training and validation studies. Of the 55 patients with NASH-HCC, 27 (49.1%) had very early-stage HCC, and six (10.9%) had early-stage HCC based on the Barcelona Clinic Liver Cancer staging system. Diagnosis with HCC-Scope was performed based on 12 items: age, sex, height, weight, AST level, ALT level, gamma-glutamyl transferase level, cholesterol level, triglyceride level, platelet count, diabetes status, and IgM-free apoptosis inhibitor of macrophage level. The FMVWG2U47 hardware (Fujitsu Co. Ltd, Tokyo, Japan) and the originally developed software were used.

RESULTS

HCC-Scope had sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 100% for the differential diagnosis between non-HCC and HCC in a training study with gray zone analysis. It was also excellent in the validation study (95.0% sensitivity, 100% specificity, 100% PPV, and 97.1% NPV with gray zone analysis and 95.2% sensitivity, 100% specificity, 100% PPV, and 97.1% NPV without gray zone analysis). HCC-Scope had a significantly higher sensitivity (85.3%) and specificity (85.1%) than alpha-fetoprotein (AFP) level, AFP-L3 level, des-gamma-carboxy prothrombin (DCP) level, and the gender-age-AFP-L3-AFP-DCP (GALAD) score.

CONCLUSIONS

HCC-Scope can accurately differentially diagnose between non-HCC NASH and NASH-HCC, including very early-stage NASH-HCC.

Serum levels of immunoglobulin M-free inhibitors of macrophage/CD5L as a predictive and early diagnostic marker for nonalcoholic steatohepatitis-associated hepatocellular carcinoma

BACKGROUND

The apoptosis inhibitor of macrophage (AIM) is usually associated with the immunoglobulin M (IgM) pentamer in the blood and is dissociated from IgM in various diseases, including hepatocellular carcinoma (HCC) in nonalcoholic steatohepatitis (NASH). We aimed to elucidate whether IgM-free AIM (fAIM) is useful for detecting latent HCC in NASH.

METHODS

This research consisted of two cohort studies. The levels of serum fAIM, alpha-fetoprotein (AFP), and des-gamma carboxy prothrombin (DCP) of 18 NASH patients who developed HCC were measured during the follow-up period before HCC diagnosis (median, 4.7 years). In total, 199 patients with nonalcoholic fatty liver disease (NAFLD) were included in the HCC survey. The serum fAIM levels were analyzed using enzyme-linked immunosorbent assays.

RESULTS

In the cohort of 18 patients with HCC, 12 had high fAIM at the time of the initial blood sample, three had normal fAIM levels throughout the follow-up period, and three had fAIM elevated from normal to positive. The positive ratio of fAIM prior to HCC diagnosis remained significantly higher than that of AFP and DCP, and the fAIM ratio gradually increased. In a survey of 199 non-HCC NAFLD patients, a Cox regression analysis using independent variables, such as AFP, fAIM, age, albumin, bilirubin, and fibrosis stage, revealed that fAIM and AFP were significantly associated with the incidence of HCC.

CONCLUSIONS

During the development of NASH-HCC, AIM activation in blood appears to start even before HCC is diagnostically detectable. Thus, the serum IgM-free AIM levels could be a new, sensitive biomarker for latent NASH-HCC.

AIM-deficient mouse fed a high-trans fat, high-cholesterol diet: a new animal model for nonalcoholic fatty liver disease

Owing to changes in lifestyle, nonalcoholic fatty liver disease (NAFLD) is becoming a common form of chronic liver injury. NAFLD comprises a wide variety of disease stages, from simple steatosis to nonalcoholic steatohepatitis, which is a risk factor for the development of hepatocellular carcinoma (HCC). Because animal models for NAFLD are needed to investigate the precise pathogenesis, we aimed to establish a new mouse model employing mice deficient for apoptosis inhibitor of macrophage (AIM^−/−), which exhibit accelerated lipid storage in the liver and high susceptibility to developing HCC in response to a high-fat diet (HFD). AIM^−/− mice were fed the D09100301 diet, which contains 40 kcal% fat (trans fat 30 kcal%), high cholesterol (2%), and 40 kcal% carbohydrates (20 kcal% fructose), and then features of obesity and NAFLD including steatosis, inflammation, fibrosis, and HCC development were analyzed. Although a comparable grade of liver steatosis was promoted in AIM^−/− mice by the D09100301 diet and the standard HFD (60 kcal% largely lard fat), significantly less lipid storage in visceral fat was observed when the mice were fed the D09100301 diet. Accelerated liver inflammation was promoted by the D09100301 diet compared with the HFD, but interestingly, HCC development was decreased in mice fed the D09100301 diet. Our findings suggest that AIM^−/− mice fed the D09100301 diet exhibited a phenotype that resembled nonobese NAFLD patients and thus could be an appropriate tool to study the pathophysiology by which obesity increases the risk of HCC.

Independent modes of disease repair by AIM protein distinguished in AIM-felinized mice

Tissue macrophage-derived apoptosis inhibitor of macrophage (AIM, encoded by cd5l gene) is a circulating protein that has suppressive functions in a broad range of diseases including obesity, liver steatosis, hepatocellular carcinoma (HCC), and acute kidney injury (AKI). In healthy states, high levels of AIM circulate in the inactivated state by associating with the immunoglobulin M (IgM) pentamer in the blood, whereas during AKI, AIM dissociates from IgM and gains disease repair activity. Here, we assessed whether AIM activation via its release from IgM is required to ameliorate other diseases. To this end, we employed a mouse line in which mouse AIM was replaced with feline AIM (AIM-felinized mice). Because feline AIM rarely dissociates from IgM due to its extremely high binding affinity for IgM, these mice exhibited deficient AKI repair as in cats. When fed a high-fat diet (HFD), similar to AIM-deficient (AIM^−/−) mice, AIM-felinized mice exhibited enhanced triacylglycerol deposition in visceral adipocytes and hepatocytes, resulting in more prominent obesity and fatty liver than in wild-type mice. In contrast, the incidence of HCC after a 1-year HFD was remarkably lower in AIM-felinized mice than in AIM^−/− mice, suggesting that AIM produced by liver Kupffer macrophages might directly facilitate the elimination of HCC cells. Accordingly, the marked deposition of AIM accompanied by accumulation of Kupffer cells was obvious during HCC tumour development in AIM-felinized mice. Δsµ mice, which harbour almost no circulating AIM due to the lack of secreted IgM, showed a phenotype comparable with that of AIM-felinized mice in prevention of those diseases. Thus, blood AIM released from IgM contributes to suppression of obesity and fatty liver as in AKI, whereas macrophage-derived noncirculating AIM mainly prevents HCC development. Our study depicted two different modes of disease prevention/repair facilitated by AIM, which could be the basis for HCC therapy that works by increasing AIM expression in macrophages.

Dietary fructose-induced hepatocellular carcinoma development manifested in mice lacking apoptosis inhibitor of macrophage (AIM)

The consumption of fructose, including the use of high-fructose corn syrup as a sweetener, has increased continuously in recent decades. Although the involvement of fructose in the development of metabolic diseases has been emphasized recently, whether fructose intake increases susceptibility to steatosis-associated hepatocellular carcinoma (HCC) is unclear. Here, we investigated this issue using mice lacking a circulating protein, apoptosis inhibitor of macrophage (AIM, encoded by cd5l). AIM does not induce carcinogenesis of hepatocytes, but provokes necrotic death specifically in AIM-bound cancer cells through complement cascade activation, thereby preventing HCC tumor development in wild-type mice. When subjected to a high-fructose diet (HFrD), AIM-deficient (AIM^-/- ) mice showed liver steatosis and subsequent liver inflammation as well as fibrosis, but at much milder levels compared with mice fed a high-fat diet. However, AIM^-/- mice were markedly susceptible to HCC tumor development, whereas no wild-type mice developed the disease. Systemic metabolic states, including obesity and insulin resistance, were similar in both types of mice after HFrD challenge, indicating no influence of AIM on HFrD-induced metabolic changes. Our results suggest that dietary fructose increases the risk for liver carcinogenesis and that individuals with low blood AIM levels may be susceptible to HCC under chronic fructose intake.