Apolipoproteins A‐I and A‐II downregulate neutrophil functions

Abstract

This work reports the effect of the apolipoproteins A-I and A-II (apoA-I and apoA-II) on the release of tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, IL-8, and IL-1 receptor antagonist (IL-1Ra) and on the oxidative burst of human neutrophils. By themselves, apoA-I and apoA-II do not affect the basal liberation of these cytokines, whereas apoA-I affects the release of IL-1beta from lipopolysaccharide (LPS)-stimulated neutrophils and apoA-II affects IL-8 released from LPS-stimulated neutrophils. ApoA-II also decreases the production of IL-8 released by neutrophils stimulated with the acute phase apolipoprotein serum amyloid A. Both apoA-I and apoA-II exerted approximately 30% inhibition on the oxidative burst of neutrophils stimulated by opsonized zymosan, as revealed by the luminol-enhanced chemiluminescence assay. These findings give additional support to the idea that the role of human plasma lipoproteins and apolipoproteins goes beyond their function in lipid transport and metabolism. HDL apolipoproteins appear to be a class of mediators that can participate in the regulation of the activity of neutrophils.

Protein adsorption steers blood contact activation on engineered cobalt chromium alloy oxide layers

“…580 Moreover, in proteins eluted from TREATED N surfaces -onto 581 which many neutrophils adhered during blood exposure -highest 582 quantities of plasminogen were found, while significantly lower 583 amounts of apolipoprotein A and a2-macroglobulin were detected. 584 Previous findings suggested that a2-macroglobulin inhibits leuko-585 cyte adhesion to biomaterials surfaces [39], and apolipoprotein A 586 reduces neutrophil recruitment and function [40][41][42], while plas-587 minogen recruits neutrophils [43]. We conclude that the 588 TREATED N surfaces were therefore covered with less neutrophil …”

“…Surface-specific blood reactions were confirmed by scanning electron micro- 41 scopy and the adsorbed protein layers were characterized by mass spectrometry. This powerful 42 proteomics tool allowed the identification and quantification of over hundred surface-adhering proteins. 43 Proteins associated with the coagulation cascade, platelet adhesion and neutrophil function correlated 44 with the various blood surface activations observed.…”

Interaction between serum amyloid A and leukocytes—A possible role in the progression of vascular complications in diabetes

“…In vitro, SAA induces the expression and release of proinflammatory cytokines such as tumor necrosis factor-alpha (TNF-␣), interleukin 1beta (IL-1␤) and the chemokine interleukin-8 (IL-8) in neutrophils and monocytes [2][3][4][5]. Furthermore, SAA acts as a priming agent, rendering the neutrophils more responsive to opsonized particles [6].…”

Prognostic value of lipoproteins and their relation to inflammatory markers among patients with coronary artery disease

“…Functional assays and flow cytometry analyses show that apoA-I inhibits contact-mediated activation of monocytes by binding to stimulated T cells, thus inhibiting TNF-a-and IL-1h-production [21]. Furthermore, apoA-I downregulates neutrophile function [22], and inhibits monocyte inflammatory functions in peripheral blood monocytes activated by either specific antigens or lectins without affecting cell proliferation [21].…”