Reliability of caspase activity as a biomarker of hepatic apoptosis in nonalcoholic fatty liver disease

Hepatocyte and immune cell crosstalk in non-alcoholic fatty liver disease

Introduction: Nonalcoholic fatty liver disease (NAFLD) is the most widespread chronic liver disease in the world. It can evolve into nonalcoholic steatohepatitis (NASH) where inflammation and hepatocyte ballooning are key participants in the determination of this steatotic state.Areas covered: To provide a systematic overview and current understanding of the role of inflammation in NAFLD and its progression to NASH, the function of the cells involved, and the activation pathways of the innate immunity and cell death; resulting in inflammation and chronic liver disease. A PubMed search was made with relevant articles together with relevant references were included for the writing of this review.Expert opinion: Innate and adaptive immunity are the key players in the NAFLD progression; some of the markers presented during NAFLD are also known to be immunity biomarkers. All cells involved in NAFLD and NASH are known to have immunoregulatory properties and their imbalance will completely change the cytokine profile and form a pro-inflammatory microenvironment. It is necessary to fully answer the question of what initiators and metabolic imbalances are particularly important, considering sterile inflammation as the architect of the disease. Due to the shortage of elucidation of NASH progression, we discuss in this review, how inflammation is a key part of this development and we presume the targets should lead to inflammation and oxidative stress treatment.

Nonalcoholic fatty liver may increase the risk of operation in patients with fatty liver and the frequency of cancer in their first-degree relatives

BACKGROUND

Fatty liver is a common disease in developed countries. We investigated the frequency of operation in patients with fatty liver and the frequency of cancer in their first-degree relatives.

METHODS

In this study, we evaluated 105 patients with biopsy-proven nonalcoholic fatty liver disease (NAFLD), 121 patients with hepatitis C (61 patients with fatty liver and 60 patients without fatty liver), 50 patients with inflammatory bowel disease (IBD), and 109 patients with dyspepsia as a control group.

RESULTS

There was no difference for sex, mean age, and marital status among the groups, except that patients with IBD were younger than others (p < 0.001). The frequency of cancer in family was as follows: 18 % in IBD, 9 % in dyspepsia, 28 % in hepatitis C with hepatic steatosis, 21.5 % in hepatitis C without steatosis, and 27 % in NAFLD (p = 0.006). Then, we divided the study group into two groups-group 1: IBD + dyspepsia + hepatitis C without hepatic steatosis, and group 2: hepatitis C with hepatic steatosis + NAFLD-and performed the same analysis. We found that the frequency of cancer in family was 16 % in group 1 (the patients without fatty liver) vs. 24.4 % in group 2 (those with fatty liver; p = 0.037). We also investigated the rate of operation in patients. The results were as follows: 33 % in group 1 vs. 43 % in group 2 (p = 0.043).

CONCLUSIONS

Independently of the underlying chronic diseases, occurrence of fat in the liver increased the frequency of operation in patients with fatty liver and the rate of cancer in their first-degree relatives. Understanding the underlying causes of fatty liver forms might decrease the cancer frequency in the population and number of operation in patients with fatty liver.

From fatty liver to fibrosis: A tale of “second hit”

Although much is known about how fat accumulates in the liver, much remains unknown about how this causes sustained hepatocellular injury. The consequences of injury are recognized as nonalcoholic steatohepatitis (NASH) and progressive fibrosis. The accumulation of fat within the hepatocytes sensitizes the liver to injury from a variety of causes and the regenerative capacity of a fatty liver is impaired. An additional stressor is sometimes referred to as a “second hit” in a paradigm that identifies the accumulation of fat as the “first hit”. Possible candidates for the second hit include increased oxidative stress, lipid peroxidation and release of toxic products such as malondialdehyde and 4-hydroxynonenal, decreased antioxidants, adipocytokines, transforming growth factor (TGF)-β, Fas ligand, mitochondrial dysfunction, fatty acid oxidation by CYPs (CYP 2E1, 4A10 and 4A14), and peroxisomes, excess iron, small intestinal bacterial overgrowth, and the generation of gut-derived toxins such as lipopolysaccharide and ethanol. Oxidative stress is one of the most popular proposed mechanisms of hepatocellular injury. Previous studies have specifically observed increased plasma and tissue levels of oxidative stress markers and lipid peroxidation products, with reduced hepatic and plasma levels of antioxidants. There is also some indirect evidence of the benefit of antioxidants such as vitamin E, S-adenosylmethionine, betaine, phlebotomy to remove iron, and N-acetylcysteine in NASH. However, a causal relationship or a pathogenic link between NASH and oxidative stress has not been established so far. A number of sources of increased reactive oxygen species production have been established in NASH that include proinflammatory cytokines such as tumor necrosis factor (TNF)-α, iron overload, overburdened and dysfunctional mitochondria, CYPs, and peroxisomes. Briefly, the pathogenesis of NASH is multifactorial and excess intracellular fatty acids, oxidant stress, ATP depletion, and mitochondrial dysfunction are important causes of hepatocellular injury in the steatotic liver.