Disruption of macrophage cell volume drives inflammatory responses and type I interferon signaling.

Macrophages coordinate inflammatory and immune responses to threats, yet how they interpret diverse danger signals to tailor inflammation remains unclear. Disturbances in extracellular and intracellular homeostasis alter cell volume, but the consequences for macrophage inflammatory responses are poorly understood. We demonstrate that macrophages use cell volume control as a danger-sensing mechanism to promote and augment inflammation. Using volume-regulated anion channel (VRAC)-deficient macrophages, which lack cell volume control under hypo-osmotic conditions, we show that cell volume disruptions drive transcriptomic reprogramming and induction of inflammation. Cell volume disruption induced type I interferon signaling through a DNA- and TBK1-dependent mechanism, but independent of cGAS and 2'3'-cGAMP transport. VRAC deficiency enhanced macrophage antiviral responses to influenza infection. Cell volume changes synergized with diverse pathogen-associated molecular pattern-mediated signaling to augment type I interferon responses and exacerbate the cytokine storm in mouse models of hyperinflammation. Our findings highlight cell volume as an important regulator in shaping inflammatory responses, expanding our understanding of how macrophages sense complex danger signals.