TNF and infection: In this regard, TNF-α levels increase following stroke [24,27], acute ischemic stroke [27], trauma [23], chronic neuroinflammation [26], hemorrhage, infection/sepsis [25], COPD, etc. Since TNF-α disrupts BBB integrity by stimulating PC migration [31], together with the fact that miR638 has been shown to influence cancer cell migration [49,50], it is feasible that TNF-α mediates its BBB disruptive actions by stimulating miR638.