Elevated levels of liver methylglyoxal and d -lactate in early-stage hepatitis in rats

Methylglyoxal and Its Adducts: Induction, Repair, and Association with Disease

Metabolism is an essential part of life that provides energy for cell growth. During metabolic flux, reactive electrophiles are produced that covalently modify macromolecules, leading to detrimental cellular effects. Methylglyoxal (MG) is an abundant electrophile formed from lipid, protein, and glucose metabolism at intracellular levels of 1-4 μM. MG covalently modifies DNA, RNA, and protein, forming advanced glycation end products (MG-AGEs). MG and MG-AGEs are associated with the onset and progression of many pathologies including diabetes, cancer, and liver and kidney disease. Regulating MG and MG-AGEs is a potential strategy to prevent disease, and they may also have utility as biomarkers to predict disease risk, onset, and progression. Here, we review recent advances and knowledge surrounding MG, including its production and elimination, mechanisms of MG-AGEs formation, the physiological impact of MG and MG-AGEs in disease onset and progression, and the latter in the context of its receptor RAGE. We also discuss methods for measuring MG and MG-AGEs and their clinical application as prognostic biomarkers to allow for early detection and intervention prior to disease onset. Finally, we consider relevant clinical applications and current therapeutic strategies aimed at targeting MG, MG-AGEs, and RAGE to ultimately improve patient outcomes.

Utilizing methylglyoxal and D-lactate in urine to evaluate saikosaponin C treatment in mice with accelerated nephrotoxic serum nephritis

The relationship between methylglyoxal (MGO) and D-lactate during saikosaponin C (SSC) treatment of mice with accelerated nephrotoxic serum (NTS) nephritis was investigated. NTS nephritis was induced by administration of anti-basement membrane antibodies to C57BL/6 mice and three dosages of SSC were administered for 14 days. Proteinuria, blood urea nitrogen, serum creatinine, renal histology, urinary MGO and d-lactate changes were examined. Compared to the NTS control group, the middle dosage (10 mg/kg/day) of SSC significantly alleviated the development of nephritis based on urine protein measurements (34.40 ± 6.85 vs. 17.33 ± 4.79 mg/day, p<0.05). Pathological observation of the glomerular basement membrane (GBM) revealed monocyte infiltration, hypertrophy, and crescents were alleviated, and injury scoring also showed improved efficacy for the middle dose of SSC during nephritis (7.92 ± 1.37 vs. 3.50 ± 1.14, p<0.05). Moreover, the significant decreases in urinary levels of MGO (24.71 ± 3.46 vs. 16.72 ± 2.36 μg/mg, p<0.05) and D-lactate (0.31 ± 0.04 vs. 0.23 ± 0.02 μmol/mg, p<0.05) were consistent with the biochemical and pathological examinations. This study demonstrates that MGO and D-lactate may reflect the extent of damage and the efficacy of SSC in NTS nephritis; further studies are required to enable clinical application.

Plasma claudin-3 is associated with tumor necrosis factor-alpha-induced intestinal endotoxemia in liver disease

OBJECTIVE

To investigate intestinal endotoxemia (IETM), intestinal permeability (IP) and cytokine activity in patients with liver cirrhosis (LC).

MATERIALS AND METHODS

Twenty-nine patients with chronic hepatitis B (CHB), 28 with compensated LC, 33 with decompensated LC, 24 with spontaneous bacterial peritonitis (SBP), 26 with acute-on-chronic liver failure (ACLF), and 24 with decompensated LC complicated by hepatocellular carcinoma (HCC) were recruited. Thirty-one healthy people were included as a control group. Plasma tumor necrosis factor (TNF)-α, interferon (IFN)-γ, D-lactate, endotoxin, and claudin-3 levels were assayed. Data were compared using Pearson correlation testing and analysis of variance, with P < 0.05 considered significant.

RESULTS

TNF-α, claudin-3, and endotoxin levels were significantly increased (P < 0.05) in the plasma of all patients with liver disease compared with that of controls, particularly in patients with decompensated LC, SBP, ACLF, or HCC (P < 0.01). IFN-γ was significantly higher in HCC than in other liver diseases (P < 0.01). Plasma D-lactate was significantly decreased in all liver diseases, except SBP (P < 0.01). TNF-α, endotoxin, and claudin-3 levels were positively correlated (P < 0.01), but correlations of IFN-γ with endotoxin or claudin-3 were not significant. The plasma D-lactate level did not significantly correlate with either TNF-α, endotoxin, or claudin-3 levels.

CONCLUSION

Plasma claudin-3, but not D-lactate, was found to be a marker of IP in patients with liver diseases. Elevated plasma TNF-α in such patients was likely to have injured the intestinal barrier, leading to IETM, especially in end-stage LC.