# Alpha‐Lipoic Acid Reduces NLRP3/ASC Expression and IL‐1β Release in Kupffer Cells and Improves Insulin Signaling in FL83B Hepatocytes Exposed to a Conditioned Medium

## TL;DR

Alpha-lipoic acid reduces inflammation and improves insulin signaling in liver cells, offering potential for treating type 2 diabetes.

## Contribution

Demonstrates that alpha-lipoic acid modulates hepatic immune-metabolic interactions to counteract inflammation-induced insulin resistance.

## Key findings

- Alpha-lipoic acid reduced NLRP3/ASC expression and IL-1β release in Kupffer cells.
- ALA improved insulin signaling in hepatocytes exposed to conditioned medium from treated Kupffer cells.
- ALA preserved mitochondrial membrane potential and inhibited NF-κB/ERK signaling in Kupffer cells.

## Abstract

Type 2 diabetes mellitus (T2DM) is characterized by insulin resistance and chronic inflammation. This study investigated whether alpha‐lipoic acid (ALA), a redox‐active compound with established anti‐inflammatory properties, can inhibit the activation of the nucleotide‐binding oligomerization domain‐like receptor family pyrin domain‐containing 3 (NLRP3) inflammasome in lipopolysaccharide (LPS)‐stimulated Kupffer cells and mitigate inflammation‐induced insulin resistance in FL83B hepatocytes. Kupffer cells were pretreated with ALA prior to exposure to LPS and either adenosine triphosphate or nigericin to activate NLRP3 inflammasome. The resulting conditioned medium was collected for cytokine analysis and subsequently used to treat FL83B hepatocytes. ALA reduced LPS‐induced interleukin‐1β (IL‐1β) secretion in a concentration‐dependent manner, whereas a modest but significant decrease in tumor necrosis factor‐alpha (TNF‐α) was observed only at the highest dose (2000 μM; p < 0.05). Western blot analysis demonstrated that ALA suppressed the expression of NLRP3 and nuclear factor‐kappa B (NF‐κB) (p < 0.05) and inhibited the phosphorylation of extracellular signal‐regulated kinase (ERK). Additionally, ALA preserved mitochondrial membrane potential in Kupffer cells. Kupffer cells treated with ALA (100 μM) prior to LPS stimulation significantly enhanced glucose uptake and upregulated the expression of insulin signaling related proteins, including phosphorylated phosphoinositide 3‐kinase (p‐PI3K), phosphorylated protein kinase B (p‐Akt) and glucose transporter type 2 (GLUT2) expression, in FL83B hepatocytes cultured with a conditioned medium from LPS‐primed and ATP/nigericin‐stimulated Kupffer cells (p < 0.05). These findings highlight the potential of ALA as a modulator of hepatic immune‐metabolic interactions and support its therapeutic relevance for managing insulin resistance in T2DM.

Alpha‐lipoic acid (ALA) reduced NLRP3/ASC expression, attenuated upstream NF‐κB/ERK signaling, and decreased IL‐1β release while preserving mitochondrial membrane potential in murine Kupffer cells subjected to LPS priming and a second signal. Conditioned medium from ALA‐pretreated Kupffer cells (particularly 100 μM) enhanced glucose uptake and improved insulin signaling (p‐PI3K, p‐Akt, and GLUT2) in FL83B hepatocytes. Together, these findings indicate that ALA modulates hepatic immune‐metabolic crosstalk and may help counteract inflammation‐associated insulin resistance in type 2 diabetes.