Complex sentence: However, the blood--brain barrier becomes more permeable during infla, this allows some antibiotics and phagocytes to move across the BBB; although, this can allow bacteria/viruses to also move across.
Split into simpler sentences: However, the blood--brain barrier becomes more permeable during inflammation. This allows some antibiotics and phagocytes to move across the BBB; although, this can allow bacteria/viruses to also move across.