Functional chemotactic factor CP-10 and MRP-14 are abundant in murine abscesses

Abstract

Murine abscesses induced by intraperitoneal injection of a mixture of Escherichia coli, Bacteroides fragilis, and bran are established models for the study of localized infectious and inflammatory lesions. Chemotactic factors are thought to mediate the directed migration of large numbers of leukocytes into the abscess. Microorganisms located within the encapsulated lesion are not readily eliminated by the leukocytes, but their numbers are controlled over many weeks. We report the presence of large amounts of two murine S100 proteins, CP-10 and migration inhibition factor-related protein 14 (MRP-14), in abscesses as demonstrated by immunohistochemistry and measured by enzyme-linked immunosorbent assay and Western blotting (immunoblotting). High levels of CP-10 (7.7 ؎ 1 mg/ml) and MRP-14 (5.5 ؎ 1 mg/ml) were found throughout the time course of abscess development from early acute-phase lesions, which are predominantly neutrophilic, to late chronic-phase lesions, which contained more mononuclear cells. Approximately one-third of these amounts occurred as monomers (2.0 mg/ml for MRP 14 and 2.2 mg/ml for CP-10). Abscess fluid was strongly chemotactic, and a portion of the activity was due to CP-10, indicating its important role in leukocyte recruitment. CP-10-MRP-14 complexes were present in abscess fluid, and the proteins were immunoabsorbed together. In analogy with the related human MRP-8-MRP-14 complex, these proteins could be involved in the inhibition of microbial growth. No growth inhibition occurred with 20 g of CP-10 or MRP-14 per ml or with mixtures of both, but these concentrations may have been insufficient and were not representative of the high concentrations found within abscesses. CP-10 may contribute indirectly to the antimicrobial response in abscesses by virtue of its strong chemotactic properties and its capacity to modulate the activation state of recruited leukocytes.

FGF‐2, IL‐1β and TGF‐β regulate fibroblast expression of S100A8

“…S100A8 protein in activated 3T3 fibroblasts S100A8 was not detected in unprocessed lysates or supernatants of 2.5-3 · 10 6 stimulated ⁄ unstimulated confluent 3T3 cells by western blot analyses or by double-sandwich ELISA (detection limit ¼ 0.03 nm [40]).…”

“…IgG from pooled sera was purified by Protein A-Sepharose (Amersham Pharmacia Biotech, Buckinghamshire, UK). Titer and reactivities of IgG with mS100A8 ⁄ mOxS100A8 were tested by immunoblotting and ELISA as described [40]. Pre-immune sera did not react with mS100A8 or mOxS100A8.…”

Inflammatory processes in a murine model of intra-abdominal abscess formation

“…Persistence • Viable, functional neutrophils and large amounts of the chemotactic proteins CP-10 and MRP-14 are present within abscesses. However, sequestration of bacteria within neutrophils in abscesses impairs clearance and therefore aids persistence of the lesion [25][26][27][28]. Immunity • T lymphocytes and not antibody mediate protection against abscess formation; the mechanism is unknown [9,29,30].…”

“…However, it is reasonable to hypothesize that any inhibition of oxidative killing mechanisms within neutrophils is likely to have maximal effect in lesions such as abscesses in which oxygen availability would be limiting. Established abscesses contain relatively large amounts of two murine S100 proteins, CP-10 (chemotactic protein 10) and MRP-14 (migration inhibition factor-related protein 14) [28]. Abscess fluid is also strongly chemotactic, with part of this activity due to CP-10 [28].…”

“…Established abscesses contain relatively large amounts of two murine S100 proteins, CP-10 (chemotactic protein 10) and MRP-14 (migration inhibition factor-related protein 14) [28]. Abscess fluid is also strongly chemotactic, with part of this activity due to CP-10 [28]. The ability of proteins such as CP-10 in abscesses to attract and activate neutrophils is reflected in the finding of activated, viable neutrophils in established abscesses [26].…”