Palmitate lipotoxicity is closely associated with the fatty acid-albumin complexes in BV-2 microglia.

ABSTRACT

Palmitic acid (PA) is considered a major contributor to the inflammation in many metabolic diseases; however, this role has been questioned recently for the complicated procedures in preparing PA-bovine serum albumin (BSA) complex. This study is aimed to evaluate the effect of PA-BSA complexing methods on cell viability and inflammatory responses of BV-2 cells. Three commercially available BSA brands and two types of solvents were compared for their effects on the expression of inflammatory cytokines. Three commonly used proportions of PA-BSA were tested for cell viability and inflammatory responses. We found that all the three types of BSA were proinflammatory. Both ethanol and isopropanol dampened inflammation except that 1% isopropanol treatment increased the IL-1ß level by 26%. When reducing the BSA content in PA-BSA solutions from 31 to 51, a marked increase in cell viability (11%) was seen. To our surprise, reducing BSA content in PA-BSA solutions from 51 to 101 decreased cell viability by 11%. The 51 group exhibited the lowest inflammatory profile. Either PA-BSA or BSA alone increased the entry of LPS to the cytosol, which further caused pyroptosis. In summary, we found 51 (PABSA) to be the best binding ratio for studying inflammation in BV-2 microglia. The presence of LPS in the cytosol in the context of BSA might be the reason for confounding results from palmitate studies.