TNF and neurodegenerative disease: Although this study used serum samples, it was found that serum TNF-α can directly cause blood–brain barrier dysfunction by reducing extracellular resistance and cell polarity to induce or aggravate neurodegenerative diseases (Sweeney et al., 2019; Yang et al., 2022; O’Carroll et al., 2015; Murdaca et al., 2022).