Obesity-associated microglial inflammatory activation paradoxically improves glucose tolerance

Area of Science:

• Neuroimmunology
• Metabolic Regulation
• Obesity Research

Background:

• High-fat diets (HFD) induce hypothalamic gliosis, increasing susceptibility to hyperphagia and weight gain.
• The specific role of microglia in glucose regulation, independent of body weight, remains unclear.

Purpose of the Study:

• To investigate the body-weight-independent contribution of microglia to glucose homeostasis.
• To elucidate the molecular mechanisms by which microglia regulate glucose metabolism.

Main Methods:

• Utilized cell-specific IKKβ deletion to reduce microglial nuclear factor κB (NF-κB) signaling.
• Employed genetic approaches to enhance microglial pro-inflammatory signaling (NF-κB pathway inhibitor deletion, chemogenetic activation).
• Assessed glucose tolerance in lean and obese rodents under varying dietary conditions.

Main Results:

• Reducing microglial NF-κB signaling exacerbated HFD-induced glucose intolerance, despite weight loss.
• Enhancing microglial pro-inflammatory signaling improved glucose tolerance independent of diet.
• Microglial regulation of glucose homeostasis involves a tumor necrosis factor alpha (TNF-α)-dependent pathway activating hypothalamic neurons.
• This pathway amplifies first-phase insulin secretion via parasympathetic signaling.

Conclusions:

• Microglia regulate glucose homeostasis through a body-weight-independent mechanism.
• Targeting microglial inflammatory pathways offers a potential strategy to mitigate obesity-associated glucose intolerance.