Character and Temporal Evolution of Apoptosis in Acetaminophen-Induced Acute Liver Failure*

Abstract

Objective To evaluate the role of hepatocellular and extrahepatic apoptosis during the evolution of Acetaminophen-induced acute liver failure (AALF). Design & Setting A prospective observational study in two tertiary liver transplant units. Patients 88 patients with AALF were recruited. Control groups included patients with non-AALF (n=13), non-hepatic multi-organ failure (MOF, n=28), chronic liver disease (CLD, n=19) and healthy controls (HC, n=11). Measurements Total and caspase-cleaved cytokeratin 18 (M65 and M30 measured on admission and sequentially on day 3, 7 and 10 following admission. Levels were also determined from hepatic, portal vein and systemic arterial blood in seven patients undergoing transplantation. Protein arrays of liver homogenates from AALF patients were assessed for apoptosis-associated proteins and histological assessment of liver tissue was performed. Main Results Admission M30 levels were significantly elevated in AALF and NALF patients compared to MOF, CLD and healthy controls. Admission M30 levels correlated with outcome with AUROC of 0.755 (0.639-0.885, p<0.001). Peak levels in ALF patients were seen on admission then fell significantly but did not normalize over ten days. A negative gradient of M30 from the portal to hepatic vein was demonstrated in AALF patients (p=0.042) at the time of liver transplant. Analysis of protein array data demonstrated lower apoptosis-associated protein and higher catalase concentrations in AALF liver compared to controls (p<0.05). Explant histological analysis revealed evidence of cellular proliferation with an absence of histological evidence of apoptosis. Conclusions Hepatocellular apoptosis occurs in the early phases of human AALF, peaking on day 1 of hospital admission and correlates strongly with poor outcome. Hepatic regenerative/tissue repair responses prevail during the later stages of ALF where elevated levels of M30 are likely to reflect epithelial cell death in extra-hepatic organs.

Apoptosis or Necrosis in Acetaminophen-Induced Acute Liver Failure? New Insights From Mechanistic Biomarkers*

“…In addition, they showed a negative gradient of M30 from the portal to the hepatic vein at later time points, suggesting that M30 could not come from the liver. This conclusion was supported by the absence of apoptotic cell death in the explant (10). These data are the first to provide evidence for caspase activation in extrahepatic tissue during AALF.…”

“…Nevertheless, consistent with previous reports (11,12), M30 levels were highest at the time of admission, suggesting that hepatocellular apoptosis occurs in the early phase of acetaminophen hepatotoxicity. Although previous work in our laboratory failed to detect active caspase-3 in plasma from acetaminophen overdose patients with liver injury (13), Possamai et al (10) in their study pointed out that these patients may have presented too late to detect markers of apoptosis. However, this is not very likely.…”

“…Interestingly, Possamai et al (10) reported that higher M30 but not M65 levels at admission were correlated with poor outcome (death or need for liver transplant) in their study. This is supported by a recent report of ALF patients of different etiologies, which indicated that M30 levels enhanced the predictability of poor outcome (14).…”

“…The assumption is that M30 levels in blood reflect apoptotic cell death. Using these variables, Possamai et al (10) showed that M30 levels are elevated in serum early after acetaminophen overdose and subsequently decline but remain significantly above baseline up to 10 days. In addition, they showed a negative gradient of M30 from the portal to the hepatic vein at later time points, suggesting that M30 could not come from the liver.…”

Acetaminophen hepatotoxicity: an updated review

“…Animal studies had previously suggested necrotic death due to depletion of intracellular ATP to be the primary mechanism, but a more recent study demonstrated (Bunchorntavakul and Reddy 2013)] 1 3 increased serum markers of apoptosis (caspase cleaved CK-18, also referred to as M30) in patients with acetaminophen-induced ALF, compared to matched controls. Additionally, M30 levels on admission predicted progression to liver transplantation or death with a sensitivity of 89 % and a specificity of 69 %, suggesting a critical role of apoptosis in the progression of ALF in acetaminophen overdose (Possamai et al 2013). …”