Understanding how sex hormones interact with ion channels in immune cells could reframe how researchers think about sex-based differences in neuroinflammation and macrophage function. THIK-1, a two-pore domain potassium channel (K2P), is highly expressed in microglia — the brain's resident immune cells — and macrophages, where it governs membrane excitability and inflammatory signaling. The discovery that estradiol directly inhibits this channel adds a mechanistic layer to longstanding observations that estrogen modulates neuroinflammatory responses.
Using heterologous expression systems and patch-clamp electrophysiology in mouse models, the investigators found that 17β-estradiol suppresses THIK-1 current by roughly 40%, with a half-maximal inhibitory concentration of approximately 4.9 μM. Molecular docking simulations pointed to a structural cavity above the channel's so-called Y gate — termed the "pond" — as the primary estradiol binding region. Alanine-substitution mutagenesis confirmed that residues F142, V269, and Y273 within this pond are critical for the inhibitory effect. Notably, mutations at F145 and F276, located outside this region, paradoxically enhanced steroid-mediated inhibition across multiple estrogens and progesterone, suggesting that conformational flexibility around the pond amplifies steroid access. A naturally occurring human THIK-1 variant (T237S) showed a milder version of this enhanced-inhibition phenotype, hinting at possible interindividual variation in estrogen sensitivity at this channel.
This finding sits at a productive intersection of ion channel pharmacology, neuroimmunology, and endocrinology. THIK-1 has emerged as a regulator of NLRP3 inflammasome activation in microglia, linking it to conditions such as Alzheimer's disease, multiple sclerosis, and chronic pain — all of which show sex-biased prevalence. The IC50 of ~4.9 μM is pharmacologically high relative to circulating estradiol levels, raising questions about physiological relevance at baseline; however, locally elevated concentrations in neural tissue or during hormonal fluctuation could narrow that gap. The study is limited to in vitro and computational methods with mouse channels, and causal claims about human neuroinflammation remain speculative. Still, identifying a discrete structural binding site positions THIK-1 as a tractable target for steroid-inspired channel modulators, making this an incremental but mechanistically precise contribution to the field.