A CLOCK-targeting lncRNA induces trained immunity against tuberculosis.

Trained immunity confers innate immune memory via metabolic and epigenetic reprogramming, yet the intercellular mediators regulating this process in host defense remain largely elusive. Here, through plasma exosomal profiling of tuberculosis (TB)-resistant individuals, we identify a trained immunity-inducing long non-coding RNA (lncRNA), termed tuberculosisresister-derived CLOCK regulator 1 (TRCR1). Mechanistically, exosome-derived TRCR1 collaborates with the RNA-binding protein FXR2 to stabilize CLOCK mRNA by forming lncRNA-protein-mRNA complexes in monocytes, thus enhancing circadian regulator CLOCK expression and promoting CLOCK-mediated histone H3 acetylation (K9/K14) at immune gene promoters, ultimately establishing epigenetic memory-mediated antimicrobial activity. We further reveal that Mycobacterium tuberculosis (Mtb)-secreted protein MPT53 induces lung epithelial cells to release TRCR1-enriched exosomes. In mice, TRCR1 training strengthens host anti-Mtb immunity and improves Bacille Calmette-Guérin (BCG) vaccine efficacy. Collectively, our findings unveil an intercellular TRCR1-FXR2-CLOCK axis driving trained immunity at the lung-systemic immune interface, providing a strategy for refining BCG vaccination and preventing infectious diseases.