In obesity, the rise in IL-1β mainly comes from inflamed adipose tissue, especially adipose tissue macrophages that accumulate around stressed, enlarged fat cells and activate the NLRP3 inflammasome, which drives IL-1β production.

Main sources

  • Adipose tissue macrophages: As fat tissue expands, immune cells infiltrate it and macrophages become a major local source of IL-1β.
  • Stressed adipocytes and fat-tissue precursors: Obese adipose tissue creates signals that prime inflammation, and IL-1β is part of this inflammatory loop in fat tissue.
  • Gut-derived inflammatory signals: Obesity is also linked to metabolic endotoxemia, where microbial products such as LPS can amplify inflammatory signaling upstream of IL-1β.

Why it rises

Obesity creates a chronic low-grade inflammatory state, so enlarging fat cells become hypoxic, stressed, and more likely to recruit immune cells that produce IL-1β. That inflammation can then worsen insulin resistance and further reinforce IL-1β signaling.

Simple way to think about it

A useful mental model is: more fat cell stress + more immune-cell infiltration + more inflammasome activation = more IL-1β. So the increase is not from one single place, but mostly from inflamed adipose tissue and the immune cells inside it.

TL;DR

The IL-1β increase in obesity comes primarily from inflamed adipose tissue macrophages , with contributions from stressed fat tissue and inflammatory gut-metabolic signals.