Shedding of sCD14 by bovine neutrophils following activation with bacterial lipopolysaccharide results in down-regulation of IL-8

Abstract

-CD14, the leukocyte co-receptor for lipopolysaccharide (LPS), is important in the response of bovine polymorphonuclear neutrophil leukocytes (PMN) to Gram-negative bacteria. In other species, the expression of CD14 on the surface of PMN was shown to increase after exposure to inflammatory stimuli. These newly expressed molecules may originate from either an intracellular pool or through new gene expression. We sought to characterize bovine PMN cell surface expression and shedding of CD14 molecules, and CD14's effect on secretion of the chemoattractants IL-8 and IL-1β by PMN. Bovine PMN were incubated in RPMI for 20 h at 37 • C with LPS (1, 10, 100 µg/mL). IL-8 release increased with treatment of 1 µg/mL LPS, but decreased 41.5 and 95% at the 10 and 100 µg/mL concentrations of LPS, respectively. In contrast, shedding of CD14 from the surface of PMN only increased at the highest concentration of LPS (100 µg/mL). Secretion of IL-1β was similar regardless of the LPS concentration used to stimulate PMN. The effect of PMN concentration (1 × 10 7 , 2.5 × 10 7 , 5 × 10 7 , and 10 × 10 7 /mL) on CD14 cell surface expression and shedding of IL-8 and IL-1β were also determined. Shedding of CD14 by PMN increased with increasing concentration of PMN after exposure to 0.1 and 10 µg/mL of LPS, while secretion of IL-8 decreased. IL-1β increased at the highest concentration of PMN. The use of real time polymerase chain reaction showed that CD14 mRNA expression was not different between control and LPS-stimulated cells, indicating that the sCD14 came from either membrane bound CD14 or a preformed pool. Our results demonstrate that release of CD14 from PMN suppresses secretion of IL-8, and may be an important regulatory mechanism for controlling excessive migration of PMN into the bovine mammary gland.CD14 / IL-8 / LPS / neutrophil / bovine

Co-cultures of multiple cell types mimic pulmonary cell communication in response to urban PM10

“…A study of respiratory damage in children chronically exposed to urban pollution in Mexico City showed that serum levels of IL-8 were decreased when compared with children living in a cleaner environment [35]. The downregulation of IL-8 has been related to different factors, such as relatively late sampling [36], the presence of IL-4 and IL-10 [37], and soluble receptors of TNF-a or CD14 [38,39]. In the present study, decreases were observed in the IL-8 secretion by A549 cells and by the biculture of A549 + HMC-1, but large increases in IL-8 secretion were observed in the HMC-1 + THP-1 biculture, the triculture and the triculture with EAHY926 at concentrations of 10 and 30 mg?cm -2 PM10, followed by a decrease at 100 mg?cm -2 .…”

Differential Expression of Interleukin-8 by Polymorphonuclear Leukocytes of Two Closely Related Species, Ovis canadensis and Ovis aries , in Response to Mannheimia haemolytica Infection

“…The association of LPS-bound CD14 with Toll-like receptor 4 and the accessory protein MD-2 triggers the eventual production of effector proteins such as IL-8. Sohn et al (29) have demonstrated a correlation between the levels of soluble CD14 and IL-8 production.…”

Application of Acute Phase Proteins for Monitoring Inflammatory States in Cattle

“…In this review we will focus on sCD14 as an APP. The serum sCD14 is believed to originate from enzymatic cleavage of its membrane homologue mCD14 through the action of specific phospholipases or proteases (Bazil et al, 1989, Sohn et al, 2007. It was first described by Maliszewski et al (1985) as a culturesupernatant blocking factor, soluble My 23, an antigen from human myeloid cells that was able to block staining of monocytes by anti-CD14 monoclonal antibodies.…”

“…Soluble CD14 also functions as a soluble receptor for bacterial LPS to cells that do not express CD14 such as epithelial and endothelial cells and thereby activates TLR-4 and the release of cytokines (Frey et al, 1992;Kitchens & Thompson, 2005). Toll-like receptor 4 mediates cellular responses to microbial LPS and acts as a co-receptor with mCD14 for LPS (Sohn et al, 2007). Soluble CD14 also has pro-inflammatory activities in the extravascular compartments where it increases resistance to bacteria.…”

“…An intracellular pool of CD14 exists in bovine PMN and is capable of translocating to the cell surface as mCD14 (Paape et al, 1996). Research conducted by Sohn et al (2007) indicated that mCD14 expressed on bovine neutrophils is a source of plasma sCD14 in cattle. Moreover, they showed that sCD14 is shed from bovine neutrophils after stimulation by LPS.…”