TGFB1 and infectious otitis media: Here, documented BBB impairment revealed by the decrease of tight junction proteins (Figure 2B), accompanied by a significant decrease of active form TGF-β1, as it was measured in brain tissue of AOM mice, reflected further in TGF-β1 decreased signaling, revealed by the reduced protein level of TGF-β1 and phosphorylated intracellular effector protein SMAD3, after its recruitment to the TGF-βRII receptor.