The Effect of C-Reactive Protein Isoforms on Nitric Oxide Production by U937 Monocytes/Macrophages.

ABSTRACT: Inflammation is regulated by many endogenous factors including estrogen, a steroid hormone that declines with increasing age, leading to excessive inflammation in the elderly. C-reactive protein (CRP) is an acute phase inflammatory protein that exists in two forms, native CRP (nCRP) and monomeric CRP (mCRP), which mediate distinct biological activities. It is unclear how each CRP isoform mediates nitric oxide (NO), a signaling molecule generated by NO synthase (NOS). This study investigated whether CRP isoforms have distinct effects on NO production by unstimulated and lipopolysaccharide (LPS)-activated monocytes/macrophages and whether estrogen mediates CRP-induced NO production in an in vitro model of aging. NO and inducible NOS (iNOS) were measured (n?=?12) by the Griess assay and an enzyme-linked immunosorbent assay, respectively following incubation (24?h) of human-derived U937 monocytes/macrophages with CRP isoforms [(nCRP)?=?500 and 1,000?µg/ml; (mCRP)?=?100 and 250?µg/ml] in the absence or presence of 17 beta-estradiol (1?×?10-7, 1?×?10-8, and 1?×?10-9?M). The response to each CRP isoform and estrogen was dependent on the differentiation and activation status of cells. Monocytes with or without prior LPS-activation significantly increased (P??0.05) on NO/iNOS production by unactivated or LPS-activated macrophages, whereas nCRP significantly (P?

SUBMITTER: Sproston NR 

PROVIDER: S-EPMC6036124 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature