Increased TNF-α and PGI 2, but not NO release from macrophages in 18-month-old rats

Abstract

TNF-α is an important pro-inflammatory mediator that influences host defense against infection and cancer. Previous examinations of TNF-α release and synthesis within the context of age have provided conflicting data, as both increased and decreased TNF-α synthesis have been described in aged populations. The present study was designed to reevaluate TNF-α production and synthesis in primary cultured peritoneal macrophages of young and 18-month-old rats. We were also interested in the link between the production of this cytokine and other important mediators, such as prostaglandin I 2 (PGI 2) and nitric oxide (NO) in these rats. Primary cultured peritoneal macrophages of rat were stimulated with 1.0 μg/ml of lipopolysacharide (LPS) for 12 h. The level of TNF-α protein in culture supernatant was measured by enzyme-linked-immunosorbent-assay (ELISA), and TNF-α mRNA production was assessed by semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR). At the same time, the levels of NO and PGI 2 were measured. Macrophages from 18-month-old rats produced more TNF-α protein, PGI 2 and TNF-α mRNA than those from the young rats (2 month). There was no difference in NO production of macrophages between 18-month-old and young rats. The results demonstrate that TNF-α and PGI 2 production by rat macrophages increase with age. The results also suggest that NO might not contribute to the increased TNF-α production in 18-month-old rat macrophages.