Blocking exosome release from inflammatory PDLSCs reversed this effect, downregulating M1 markers and enhancing M2-related expression, confirming that these exosomes drive M1 macrophage polarization [25]. The authors proposed that the elevated salivary exosomal PD-L1 mRNA observed in severe periodontitis could reflect an adaptive host mechanism to inhibit further tissue destruction. The gene discussed is CD274; the disease is periodontitis.