Activation of apoptosis inhibitor of macrophage is a sensitive diagnostic marker for NASH-associated hepatocellular carcinoma

The Growing Landscape of NAFLD-Associated Hepatocellular Carcinoma and Its Impact in Surveillance

Liver cancer is globally the third leading cause of death from cancer. Hepatocellular carcinoma (HCC) develops in patients with underlying liver disease. The fraction of HCC attributed to nonalcoholic fatty liver disease (NAFLD) shows an accelerated increase in the last decades, being already responsible for 15% of all HCC cases. Similar to other causes of liver cirrhosis, patients with NAFLD-associated cirrhosis should be enrolled in HCC-screening programs, yet these patients are under-screened, and currently are less than half likely to be proposed for HCC screening as compared to patients with HCV-associated cirrhosis. NAFLD-associated HCC has the peculiarity of occurring in precirrhotic phases in 20-50% of the cases. Currently, HCC screening in precirrhotic NAFLD patients is not routinely recommended, since the risk of developing HCC is very low. However, because NAFLD affects one-third of the worldwide population, noncirrhotic NAFLD already accounts for 6% of HCC cases. As such, it is pressing to develop stratification tools, in order to personalize the individual risk of HCC development in a patient with NAFLD, allowing precision HCC-screening programs. This review summarizes the epidemiology of NAFLD-associated HCC with a critical analysis of current HCC-screening recommendations.

AIM/CD5L ameliorates autoimmune arthritis by promoting removal of inflammatory DAMPs at the lesions

The hallmark of autoimmune arthritis is the preceding autoantibody production and the following synovial inflammation with hyperplasia and tissue destruction of the joints. The joint inflammation is mediated not only by effector lymphocytes and auto-antibodies but also chronic activation of innate immunity, particularly promoted by the danger-associated molecular patterns (DAMPs). Here we show that apoptosis inhibitor of macrophage (AIM, also called CD5L) protein regulates arthritis by promoting removal of lesional DAMPs both physiologically and therapeutically. When the autoimmune arthritis was promoted by injecting a cocktail of anti-collagen antibodies without type-II collagen immunization, AIM-deficient (AIM-/-) mice exhibited more exacerbated and sustained swelling at multiple joints with greater synovial hyperplasia and bone erosion than wild-type mice. Administration of recombinant AIM (rAIM) reduced S100A8/9, a major DAMP known to be involved in arthritis progression, and decreased various inflammatory cytokines at the lesions in antibody-injected AIM-/- mice, leading to marked prevention of arthritis symptoms. In human rheumatoid arthritis (RA) patients, AIM was more activated via dissociating from IgM-pentamer in response to DAMPs-mediated inflammation both in serum and synovial fluid than in healthy individuals or non-autoimmune osteoarthritis patients, suggesting a disease-regulatory potency of AIM also in human RA patients. Thus, our study implied a therapeutic availability of rAIM to prevent arthritis symptoms targeting DAMPs.

CD5L is a canonical component of circulatory IgM

Immunoglobulin M (IgM) is an evolutionary conserved key component of humoral immunity, and the first antibody isotype to emerge during an immune response. IgM is a large (1 MDa), multimeric protein, for which both hexameric and pentameric structures have been described, the latter additionally containing a joining (J) chain. Using a combination of single-particle mass spectrometry and mass photometry, proteomics, and immunochemical assays, we here demonstrate that circulatory (serum) IgM exclusively exists as a complex of J-chain-containing pentamers covalently bound to the small (36 kDa) protein CD5 antigen-like (CD5L, also called apoptosis inhibitor of macrophage). In sharp contrast, secretory IgM in saliva and milk is principally devoid of CD5L. Unlike IgM itself, CD5L is not produced by B cells, implying that it associates with IgM in the extracellular space. We demonstrate that CD5L integration has functional implications, i.e., it diminishes IgM binding to two of its receptors, the FcαµR and the polymeric Immunoglobulin receptor. On the other hand, binding to FcµR as well as complement activation via C1q seem unaffected by CD5L integration. Taken together, we redefine the composition of circulatory IgM as a J-chain containing pentamer, always in complex with CD5L.

From NAFLD to HCC: Advances in noninvasive diagnosis

Non-alcoholic fatty liver disease (NAFLD) has gradually become one of the major liver health problems in the world. The dynamic course of the disease goes through steatosis, inflammation, fibrosis, and carcinoma. Before progressing to carcinoma, timely and effective intervention will make the condition better, which highlights the importance of early diagnosis. With the further study of the biological mechanism in the pathogenesis and progression of NAFLD, some potential biomarkers have been discovered, and the possibility of their clinical application is gradually being discussed. At the same time, the progress of imaging technology and the emergence of new materials and methods also provide more possibilities for the diagnosis of NAFLD. This article reviews the diagnostic markers and advanced diagnostic methods of NAFLD in recent years.

Performance of GALAD score and serum biomarkers for detecting NAFLD-related HCC: a systematic review and network meta-analysis

INTRODUCTION

The incidence of nonalcoholic fatty liver disease (NAFLD)-related hepatocellular carcinoma (HCC) is increasing globally. We aimed to assess the performance of alpha-fetoprotein (AFP), AFP-L3, des-gamma-carboxy prothrombin (DCP), and GALAD score in detecting NAFLD-related HCC.

METHODS

We searched the relevant literature in PubMed, Embase and Cochrane. Conventional and network meta-analyses were performed for sensitivity, specificity, Youden index (YI), and the area under the summary receiver operator characteristic curve (AUC).

RESULTS

Fifteen studies involving 2031 NAFLD participants were included in this meta-analysis. When detecting early-stage NAFLD-related HCC, GALAD score and DCP process excellent performance. The sensitivity and AUC of DCP (0.60, 0.74, respectively) were higher than AFP (0.34, 0.59, respectively). The network meta-analysis showed that DCP and GALAD score had similar performance. In detecting all-stage NAFLD-related HCC, GALAD score (sensitivity = 0.87; YI = 0.77) performed better than AFP (sensitivity = 0.56; YI = 0.50), AFP-L3 (sensitivity = 0.39; YI = 0.36) and DCP (sensitivity = 0.73; YI = 0.62). Network meta-analysis obtained consistent results with conventional meta-analysis.

CONCLUSIONS

Due to the lower cost-effectiveness, DCP was more suitable for detecting early NAFLD-related HCC. AFP could be used in detecting all-stage NAFLD-related HCC.

The comprehensive role of apoptosis inhibitor of macrophage (AIM) in pathological conditions

CD5L/AIM (apoptosis inhibitor of macrophage), as an important component in maintaining tissue homeostasis and inflammation, is mainly produced and secreted by macrophages but partially dissociated and released from blood AIM-IgM. AIM plays a regulatory role in intracellular physiological mechanisms, including lipid metabolism and apoptosis. AIM not only increases in autoimmune diseases, directly targets liver cells in liver cancer and promotes cell clearance in acute kidney injury, but also causes arteriosclerosis and cardiovascular events, and aggravates inflammatory reactions in lung diseases and sepsis. Obviously, AIM plays a pleiotropic role in the body. However, to date, studies have failed to decipher the mechanisms behind its different roles (beneficial or harmful) in inflammatory regulation. The inflammatory response is a "double-edged sword," and maintaining balance is critical for effective host defense while minimizing the adverse side effects of acute inflammation. Enhancing the understanding of AIM function could provide the theoretical basis for new therapies in these pathological settings. In this review, we discuss recent studies on the roles of AIM in lipid metabolism, autoimmune diseases and organic tissues, such as liver cancer, myocardial infarction, and kidney disease.

CD5L-associated gene analyses highlight the dysregulations, prognostic effects, immune associations, and drug-sensitivity predicative potentials of LCAT and CDC20 in hepatocellular carcinoma

BACKGROUND

The dysregulation of CD5L has been reported in hepatocellular carcinoma (HCC). However, its functions in HCC were controversial. In this study, we aimed to identify CD5L-associated pathways and markers and explore their values in HCC diagnosis, prognosis and treatment.

METHODS

HCC datasets with gene expression profiles and clinical data in TCGA and ICGC were downloaded. The immune/stroma cell infiltrations were estimated with xCell. CD5L-associated pathways and CD5L-associated genes (CD5L-AGs) were identified with gene expression comparisons and gene set enrichment analysis (GSEA). Cox regression, Kaplan-Meier survival analysis, and least absolute shrinkage and selection operator (LASSO) regression analysis were performed. The correlations of the key genes with immune/stroma infiltrations, immunoregulators, and anti-cancer drug sensitivities in HCC were investigated. At protein level, the key genes dysregulations, their correlations and prognostic values were validated in clinical proteomic tumor analysis consortium (CPTAC) database. Serum CD5L and LCAT activity in 50 HCC and 30 normal samples were evaluated and compared. The correlations of serum LCAT activity with alpha-fetoprotein (AFP), albumin (ALB) and high-density lipoprotein (HDL) in HCC were also investigated.

RESULTS

Through systemic analyses, 14 CD5L-associated biological pathways, 256 CD5L-AGs and 28 CD5L-associated prognostic and diagnostic genes (CD5L-APDGs) were identified. A risk model consisting of LCAT and CDC20 was constructed for HCC overall survival (OS), which could discriminate HCC OS status effectively in both the training and the validation sets. CD5L, LCAT and CDC20 were shown to be significantly correlated with immune/stroma cell infiltrations, immunoregulators and 31 anti-cancer drug sensitivities in HCC. At protein level, the dysregulations of CD5L, LCAT and CDC20 were confirmed. LCAT and CDC20 were shown to be significantly correlated with proliferation marker MKI67. In serum, no significance of CD5L was shown. However, the lower activity of LCAT in HCC serum was obvious, as well as its significant positive correlations ALB and HDL concentrations.

CONCLUSIONS

CD5L, LCAT and CDC20 were dysregulated in HCC both at mRNA and protein levels. The LCAT-CDC20 signature might be new predicator for HCC OS. The associations of the three genes with HCC microenvironment and anti-cancer drug sensitivities would provide new clues for HCC immunotherapy and chemotherapy.

Hepatocellular carcinoma diagnosis using a novel electrochemiluminescence immunoassay targeting serum IgM-free AIM

BACKGROUND

Recent increases in the number of patients with non-alcoholic steatohepatitis (NASH) warrant the identification of biomarkers for early detection of hepatocellular carcinoma (HCC) associated with NASH (NASH-HCC). IgM-free apoptosis inhibitor of macrophage (AIM), which generally associates with IgM in blood and exerts its biological function by dissociation from IgM, may serve as an effective biomarker for NASH-HCC. Here, we established a fully automatic and high-throughput electrochemiluminescence immunoassay (ECLIA) to measure IgM-free AIM and investigated its efficacy in diagnosing NASH-HCC and viral HCC.

METHODS

IgM-free AIM levels were measured in 212 serum samples from patients with, or without, HCC related to NASH, hepatitis B virus, and hepatitis C virus, using ECLIA. We also developed an ECLIA for measuring both IgM-free and IgM-bound AIM and investigated the existing form of AIM in blood by size-exclusion chromatography.

RESULTS

IgM-free AIM levels were significantly higher in the HCC group than in the non-HCC group, regardless of the associated pathogenesis. Moreover, the area under the receiver operating curve for IgM-free AIM was greater than that for conventional HCC biomarkers, alpha-fetoprotein or des-γ-carboxy prothrombin, regardless of the cancer stage. ECLIA counts of IgM-free AIM derived from samples fractionated by size-exclusion chromatography were significantly higher in patients with NASH-HCC than in healthy volunteers and in patients with non-alcoholic fatty liver and NASH.

CONCLUSIONS

Serum IgM-free AIM may represent a universal HCC diagnostic marker superior to alpha-fetoprotein or des-γ-carboxy prothrombin. Our newly established ECLIA could contribute to further clinical studies on AIM and in vitro HCC diagnosis.

AIM/CD5L attenuates DAMPs in the injured brain and thereby ameliorates ischemic stroke

The sterile inflammation caused by damage-associated molecular patterns (DAMPs) worsens the prognosis following primary injury such as ischemic stroke. However, there are no effective treatments to regulate DAMPs. Here, we report that AIM (or CD5L) protein reduces sterile inflammation by attenuating DAMPs and that AIM administration ameliorates the deleterious effects of ischemic stroke. AIM binds to DAMPs via charge-based interactions and disulfide bond formation. This AIM association promotes the phagocytic removal of DAMPs and neutralizes DAMPs by impeding their binding to inflammatory receptors. In experimental stroke, AIM-deficient mice exhibit severe neurological damage and higher mortality with greater levels of DAMPs and associated inflammation in the brain than wild-type mice, in which brain AIM levels increase following stroke onset. Recombinant AIM administration reduces sterile inflammation in the infarcted region, leading to a profound reduction of animal mortality. Our findings provide a basis for the therapies targeting DAMPs to improve ischemic stroke.

Association between apoptosis inhibitor of macrophage and microsatellite instability status in colorectal cancer

BACKGROUND

The microsatellite instability (MSI) in colorectal cancer (CRC) has a more favorable clinical outcome and is characterized by highly upregulated expression of various immunological checkpoints than microsatellite stable (MSS) tumors. Apoptosis inhibitor of macrophage (AIM) is a circulating protein and circulates throughout the body to remove cellular debris. The aim of this study was to evaluate the association between MSI status and AIM levels in CRC patients.

METHODS

In this study, we evaluated the levels of AIM by Enzyme Linked Immuno-Sorbent Assay (ELISA) in serum of 430 CRC patients. All patients' clinical and laboratory characteristics at initial diagnosis were collected. The relationship between AIM levels and MSI status was examined.

RESULTS

64 patients (14.9%) were identified as having MSI-H (high-frequency MSI) and 366 casess (85.1%) having MSS. Patients with an MSI-H phenotype had lower AIM levels compared with MSS patients. Moreover, AIM levels were correlated with histological type and MSI status. Logistic regression analysis revealed that decreased AIM levels were independently associated with MSI-H phenotype after adjusting confounding factors.

CONCLUSION

Reduced AIM levels are associated with MSI-H subtyping of CRC. Further research on the involvement of AIM in MSI-H CRC is needed.

Surveillance of Hepatocellular Carcinoma in Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is becoming the leading cause of hepatocellular carcinoma (HCC), liver-related mortality, and liver transplantation. There is sufficient epidemiological cohort data to recommend the surveillance of patients with NAFLD based upon the incidence of HCC. The American Gastroenterology Association (AGA) expert review published in 2020 recommends that NAFLD patients with cirrhosis or advanced fibrosis estimated by non-invasive tests (NITs) consider HCC surveillance. NITs include the fibrosis-4 (FIB-4) index, the enhanced liver fibrosis (ELF) test, FibroScan, and MR elastography. The recommended surveillance modality is abdominal ultrasound (US), which is cost effective and noninvasive with good sensitivity. However, US is limited in obese patients and those with NAFLD. In NAFLD patients with a high likelihood of having an inadequate US, or if an US is attempted but inadequate, CT or MRI may be utilized. The GALAD score, consisting of age, gender, AFP, the lens culinaris-agglutinin-reactive fraction of AFP (AFP-L3), and the protein induced by the absence of vitamin K or antagonist-II (PIVKA-II), can help identify a high risk of HCC in NAFLD patients. Innovative parameters, including a Mac-2 binding protein glycated isomer, type IV collagen 7S, free apoptosis inhibitor of the macrophage, and a combination of single nucleoside polymorphisms, are expected to be established. Considering the large size of the NAFLD population, optimal screening tests must meet several criteria, including high sensitivity, cost effectiveness, and availability.

Apoptosis Inhibitor of Macrophage, Monocyte Chemotactic Protein-1, and C-Reactive Protein Levels Are Increased in Patients with Metabolic Syndrome: A Pilot Study

Background: Apoptosis inhibitor of macrophage (AIM) and monocyte chemotactic protein-1 (MCP-1) are molecules that cause migration of M1 macrophages to visceral adipocytes, which is the first step in development of metabolic syndrome. The aim of this study is to evaluate the status of AIM and MCP-1 in metabolic syndrome and to investigate their use as biomarkers. Methods: Forty metabolic syndrome patients and 40 healthy individuals were enrolled in the study. Serum AIM, MCP-1, and C-reactive protein (CRP) levels were measured by enzyme-linked immunosorbent assay. Results: AIM, MCP-1, and CRP levels were significantly higher in the metabolic syndrome group (P < 0.01, P < 0.01, and P < 0.05, respectively). There was a positive correlation of serum AIM, MCP-1, and CRP levels with waist circumference (r = 0.480, r = 0.663, and r = 0.418, respectively; P < 0.01). Receiver operating characteristic (ROC) curve analyses revealed AIM, MCP-1, and CRP cutoff points as 2383.7 ng/mL, 172.8 pg/mL, and 0.366 mg/dL, which could be used in the diagnosis of metabolic syndrome with highest sensitivity and specificity. In the logistic regression model, including age, AIM, CRP, and MCP-1 as covariates, having serum AIM and CRP levels above cutoffs were significant independent predictors for metabolic syndrome (odds ratios 13.8 and 21.3), whereas the serum MCP-1 level was not a significant independent predictor, although the odds ratio was 2.6 (P = 0.193). Conclusions: These results suggest that AIM and MCP-1 may play a role in the pathogenesis of metabolic syndrome. AIM and CRP levels may be used as biomarkers in the diagnosis of metabolic syndrome. Although MCP-1 is not an independent predictor, its elevation in metabolic syndrome is noteworthy, which warrants further analyses in larger groups.

Secreted IgM: New tricks for an old molecule

Secreted IgM (sIgM) is a multifunctional evolutionary conserved antibody that is critical for the maintenance of tissue homeostasis as well as the development of fully protective humoral responses to pathogens. Constitutive secretion of self- and polyreactive natural IgM, produced mainly by B-1 cells, provides a circulating antibody that engages with autoantigens as well as invading pathogens, removing apoptotic and other cell debris and initiating strong immune responses. Pathogen-induced IgM production by B-1 and conventional B-2 cells strengthens this early, passive layer of IgM-mediated immune defense and regulates subsequent IgG production. The varied effects of secreted IgM on immune homeostasis and immune defense are facilitated through its binding to numerous different cell types via different receptors. Recent studies identified a novel function for pentameric IgM, namely as a transporter for the effector protein ″apoptosis-inhibitor of macrophages″ (AIM/CD5L). This review aims to provide a summary of the known functions and effects of sIgM on immune homeostasis and immune defense, and its interaction with its various receptors, and to highlight the many critical immune regulatory functions of this ancient and fascinating immunoglobulin.

Non-Cirrhotic Liver is Associated with Poor Prognosis of Hepatocellular Carcinoma: A Literature Review

Primary hepatocellular carcinoma (HCC) is the fifth most frequently reported malignancy, and it is also the second most common cause of cancer-related deaths worldwide. Although most HCC cases have been reported to develop from cirrhosis, accumulating data suggest that HCC is also closely related to non-cirrhotic chronic liver disease. Traditionally, HCC was thought to develop mostly from cirrhosis; however, an increasing number of reports have found that HCC can develop directly from inflammation without cirrhosis. The incidence of HCC in non-cirrhotic liver (HCC-NCL) is high, especially in developed countries. Studies have found that the most common cause of HCC-NCL is neglected fatty liver disease. This type of HCC has unique clinical characteristics and is closely related to metabolic disorders. Unfortunately, the prevention of HCC-NCL has not received enough attention worldwide, and there is also a lack of specific screening methods and clinical guidelines. This article mainly reviews the etiology, incidence, clinical characteristics, and screening markers of HCC-NCL to improve the understanding and prevention of this disease.

Bouchardatine analogue alleviates non-alcoholic hepatic fatty liver disease/non-alcoholic steatohepatitis in high-fat fed mice by inhibiting ATP synthase activity

BACKGROUND AND PURPOSE

Non-alcoholic hepatic fatty liver disease (NAFLD) is a manifestation of the metabolic syndrome in the liver and non-alcoholic steatohepatitis (NASH) represents its advanced stage. R17 derived from bouchardatine, shows benefits in the metabolic syndrome, but has not been tested in the liver. The present study examined the pharmacological effects of R17 in a model of NAFLD/NASH and its mode of action.

EXPERIMENTAL APPROACH

The effects of R17 were examined in mice fed a high-fat (HF) diet to induce the pathological characteristics of NAFLD/NASH and in cultures of HuH7 cells. We used histological and immunohistochemical techniques along with western blotting and siRNA. Generation of ROS and apoptosis were measured.

KEY RESULTS

Administration of R17 (20 mg·kg^-1 , i.p. every other day) for 5 weeks reversed HF-induced hepatic triglyceride content, inflammation (inflammatory cytokines and macrophage numbers), injury (hepatocyte ballooning and apoptosis, plasma levels of alanine aminotransferase and aspartate aminotransferase), and fibrogenesis (collagen deposition and mRNA expression of fibrosis markers). In cultured cells, R17 reduced cell steatosis from both lipogenesis and fatty acid influx. The attenuated inflammation and cell injury were associated with inhibition of both endoplasmic reticulum (ER) stress and oxidative stress. Notably, R17 activated the liver kinase B1-AMP-activated protein kinase (AMPK) pathway by inhibiting activity of ATP synthase, rather than direct stimulation of AMPK.

CONCLUSION AND IMPLICATIONS

R17 has therapeutic potential for NAFLD/NASH. Its mode of action involves the elimination of ER and oxidative stresses, possibly via activating the LKB1-AMPK axis by inhibiting the activity of ATP synthase.

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.

A scavenging system against internal pathogens promoted by the circulating protein apoptosis inhibitor of macrophage (AIM)

An internal system designed to ward off and remove unnecessary or hazardous materials is intrinsic to animals. In addition to exogenous pathogens, a number of self-molecules, such as apoptotic or necrotic dead cells, their debris, and the oxides or peroxides of their cellular components, are recognized as extraneous substances. It is essential to eliminate these internal pathogens as quickly as possible because their accumulation can cause chronic inflammation as well as autoimmune responses, possibly leading to onset or progression of certain diseases. Apoptosis inhibitor of macrophage (AIM, also called CD5L) is a circulating protein that is a member of the scavenger receptor cysteine-rich superfamily, and we recently found that during acute kidney injury, AIM associates with intraluminal dead cell debris accumulated in renal proximal tubules and enhances clearance of luminal obstructions, thereby facilitating repair. Thus, AIM acts as a marker for phagocytes so that they can efficiently recognize and engulf the debris as their targets. In this chapter, we give an overview of the professional and non-professional phagocytes, and how soluble scavenging molecules such as AIM contribute to improvement of diseases by stimulating phagocytic activity.

The IgM pentamer is an asymmetric pentagon with an open groove that binds the AIM protein

Soluble immunoglobulin M (IgM) forms a pentamer containing a joining (J) chain polypeptide. While IgM pentamer has various immune functions, it also behaves as a carrier of circulating apoptosis inhibitor of macrophage (AIM; also called CD5L) protein that facilitates repair during different diseases. AIM binds to the IgM pentamer solely in the presence of the J chain. Here, using a single-particle negative-stain electron microscopy, we found that the IgM pentamer exhibits an asymmetric pentagon containing one large gap, which is markedly different from the textbook symmetric pentagon model. A single AIM molecule specifically fits into the gap, cross-bridging two IgM-Fc that form the edges of the gap through a disulfide bond at one side and a charge-based interaction at the other side. The discovery of the bona fide shape of the IgM pentamer advances our structural understanding of the pentameric IgM and its binding mode with AIM.

Apoptosis and non-alcoholic fatty liver diseases

The number of patients with nonalcoholic fatty liver diseases (NAFLD) including nonalcoholic steatohepatitis (NASH), has been increasing. NASH causes cirrhosis and hepatocellular carcinoma (HCC) and is one of the most serious health problems in the world. The mechanism through which NASH progresses is still largely unknown. Activation of caspases, Bcl-2 family proteins, and c-Jun N-terminal kinase-induced hepatocyte apoptosis plays a role in the activation of NAFLD/NASH. Apoptotic hepatocytes stimulate immune cells and hepatic stellate cells toward the progression of fibrosis in the liver through the production of inflammasomes and cytokines. Abnormalities in glucose and lipid metabolism as well as microbiota accelerate these processes. The production of reactive oxygen species, oxidative stress, and endoplasmic reticulum stress is also involved. Cell death, including apoptosis, seems very important in the progression of NAFLD and NASH. Recently, inhibitors of apoptosis have been developed as drugs for the treatment of NASH and may prevent cirrhosis and HCC. Increased hepatocyte apoptosis may distinguish NASH from NAFLD, and the improvement of apoptosis could play a role in controlling the development of NASH. In this review, the association between apoptosis and NAFLD/NASH are discussed. This review could provide their knowledge, which plays a role in seeing the patients with NAFLD/NASH in daily clinical practice.