The paradoxical protective effect of malnutrition in acetaminophen-induced liver injury

Background

Malnutrition is believed to aggravate drug-induced liver injury (DILI). However, the relationship between protein malnutrition (PMN) and acetaminophen (APAP)-induced liver injury (AILI) remains unclear, particularly in low and middle income countries (LMIC) where PMN is common.

Objective

This study aimed to investigate the role of PMN on AILI in female BALB/c mice.

Methodology

PMN was induced in 15 week old female BALB/c mice by feeding a low protein diet (LPD, 10% protein) after weaning, while control mice received a normal diet (ND, 18% protein). Initially, APAP-induced lethality was assessed at different doses. Subsequently, mice were challenged with a single oral dose of APAP (300 mg/kg) to evaluate liver injury markers, oxidative stress, inflammatory cytokines, CYP2E1 expression and activity, histopathology, PCNA expression, and pharmacokinetic (PK) parameters.

Results

At a single oral dose of 500 mg/kg, APAP-induced lethality was high in the LPD group (3/4). Reducing the dose to 400 mg/kg abolished lethality in the LPD group (0/6) but not in the ND group (4/6). At 300 mg/kg, lethality was absent in both groups. Liver injury assessed by ALT, AST, and ALP levels was greater in the ND group than in the LPD group. Higher oxidative stress and cytokine levels (TNF-α and IL-6), increased PCNA expression, and pronounced histological alterations were observed in ND mice. PK analysis showed greater C_max, T_max, and AUC₀₋₄ values in the LPD group, indicating altered APAP metabolism. In addition, ND mice exhibited greater CYP enzyme expression and activity, suggesting enhanced APAP bioactivation and increased susceptibility to liver injury.

Conclusion

Our findings highlight the paradoxical vulnerability of the ND group to AILI and death. Therefore, PMN could be the reason for fewer APAP overdose-related deaths in developing countries. Further, unravelling the precise molecular mechanisms induced by nutritional changes is critical for understanding the paradoxical decline in liver injury associated with PMN.

Graphical abstract

The graphical abstract illustrates the differential effects of a normal diet (ND) and a low protein diet (LPD) on acetaminophen (APAP)-induced liver injury (AILI) in female BALB/c mice. Mice were divided into ND and LPD groups at week 0 and maintained on their respective diets for 15 weeks. Subsequently, mice were challenged with a single oral dose of APAP (300 mg/kg) to both groups, followed by collection of blood and liver samples at multiple time intervals (0, 1, 3, 6, 24, 36, 48, and 72 h) from a separate set of animals for the assessment of liver injury markers (AST, ALT, and ALP), antioxidant parameters (SOD, catalase, GSH, and MDA), cytokines (TNF-α and IL-6), CYP2E1 enzyme expression and activity, PCNA expression, histopathological evaluation, and liver damage scoring, Additionally, a separate set of animals (n = 6 per group) were used for pharmacokinetic analysis of APAP.