Role of proinflammatory cytokines in acetaminophen hepatotoxicity

Acetaminophen (APAP) intoxication has been shown to activate Kupffer cells. Kupffer cell activation is also associated with the release of proinflammatory cytokines which can induce a variety of pathophysiological responses. These studies examined whether proinflammatory cytokines are produced in response to a hepatotoxic dose of APAP, and if so, the role they play in the observed pathological response. Female B6C3F1 mice received 500 mg APAP/kg in the presence and absence of antibodies against tumor necrosis factor-alpha (TNF-alpha), interleukin-1-alpha (IL-1 alpha), and IL-1 receptor antagonist (IL-1ra). Serum TNF-alpha, IL-1 alpha, and liver-associated enzyme levels were measured. In addition, the levels of mRNA transcripts for IL-1 alpha, IL-6, and TNF-alpha from livers of treated mice were examined by reverse transcription-polymerase chain reaction (RT-PCR). Administration of APAP resulted in an immediate reduction in body temperature as well as elevated serum levels of IL-1 alpha and TNF-alpha that reached a peak at 12 and 16 hr, respectively. The reduction in body temperature was partially blocked by injection of antibodies against TNF-alpha or IL-1 alpha. Furthermore, neutralization of TNF-alpha delayed the increase in serum IL-1 alpha and liver enzyme levels. In contrast, pretreatment with IL-1ra antisera exacerbated the effect of APAP on body temperature and increased the release of liver enzymes. These data suggest that TNF-alpha and IL-1 alpha are released in response to APAP intoxication and are responsible for certain pathological manifestations of APAP-induced hepatotoxicity.