Targeting the intestinal TLR4-GABAA axis to promote stroke recovery

Background: Stroke-induced gut dysbiosis exacerbates brain injury via the Toll-like Receptor 4 (TLR4) signaling pathway. However, the role of intestinal-specific TLR4 in ischemic stroke remains unclear. This study aimed to investigate the role of intestinal-specific TLR4 in the acute phase of post-stroke recovery and to explore the underlying gut-brain mechanisms.

Methods: A murine ischemic stroke model was established, and intestinal-specific interventions were performed using TLR4 inhibitors, agonists, and conditional knockout mice. Post-stroke brain injury, systemic inflammation, and gut barrier function were systematically evaluated. Transcriptomic profiling and 16 S rRNA Sequencing were integrated to elucidate the regulatory mechanisms of intestinal TLR4 signaling in stroke outcomes.

Results: Pharmacological inhibition of intestinal TLR4 ameliorated, whereas its activation exacerbated, both cerebral and intestinal injury following stroke. Intestinal epithelial-specific TLR4 knockout (TLR4^flox/flox; Vil^Cre) significantly reduces cerebral infarction, improves neurological function, alleviates neuronal damage, decreases microglial activation, and preserves intestinal barrier integrity after stroke. Compared to brain-specific TLR4 knockout mice (TLR4^flox/flox; Emx1^Cre), intestinal epithelial-specific TLR4 knockout mice exhibit greater efficacy in alleviating brain injury, reducing systemic and neuroinflammation and protecting the gut barrier following stroke. RNA Sequencing reveals upregulation of gamma-aminobutyric acid type A (GABA_A) receptor signaling in the colon of TLR4^flox/flox; Vil^Cre mice. The protective effects of intestinal epithelial-specific TLR4 knockout are abolished by GABA_A receptor inhibition, highlighting the role of the intestinal TLR4-GABA_A axis in stroke recovery. Intestinal epithelial-specific TLR4 knockout reshapes the gut microbiota composition after stroke, and the altered microbial taxa, such as Bacteroides and Prevotella, are closely associated with improved neurological outcomes and upregulation of colonic GABA_A receptors.

Conclusion: This study identifies intestinal TLR4 as a key determinant of stroke outcomes during the acute phase and establishes the intestinal TLR4-GABA_A signaling axis as a central mechanistic pathway mediating gut-brain crosstalk after stroke.

Supplementary Information: The online version contains supplementary material available at 10.1186/s12974-025-03689-9.

GABAA receptor; Gut dysbiosis; Gut-brain axis; Ischemic stroke; Neuroinflammation; TLR4 signaling.