Macrophage Lineage Cells in Inflammation: Characterization by Colony-Stimulating Factor-1 (CSF-1) Receptor (c-Fms), ER-MP58, and ER-MP20 (Ly-6C) Expression

Abstract

Macrophage populations resident in tissues and at sites of inflammation are heterogeneous and with local proliferation sometimes evident. Using the convenient murine peritoneal cavity as an inflammation model, the appearance of macrophage lineage cells was followed with time in both thioglycollate- and sodium periodate-induced exudates. The cells were characterized by their proliferative response in vitro in response to colony-stimulating factor-1 (CSF-1) (or macrophage colony-stimulating factor [M-CSF]), particularly by their ability to form colonies in agar, in combination with flow cytometry (surface marker expression and forward and side scatter characteristics). We propose that c-Fms (CSF-1 receptor), unlike other markers, is a uniformly expressed and specific marker suitable for the detection of macrophage-lineage cells in tissues, both in the steady state and after the initiation of an inflammatory reaction. It was shown that the bone marrow myeloid precursor markers, ER-MP58 and ER-MP20 (Ly-6C), but not ER-MP12 (PECAM-1), are expressed by a high proportion of macrophage-lineage cells in the inflamed peritoneum. The macrophage colony-forming cells (M-CFCs) in a 16-hour thioglycollate-induced exudate were phenotyped as c-Fms+ERMP12−20+58+, properties consistent with their being more mature than bone marrow M-CFCs. It is proposed that ER-MP58, as well as ER-MP20, may be a useful marker for distinguishing inflammatory macrophage-lineage cells from the majority of those residing normally in tissues. © 1998 by The American Society of Hematology.

Control of macrophage lineage populations by CSF‐1 receptor and GM‐CSF in homeostasis and inflammation

“…For the wild-type macrophage response, the presence of Ly6C hi macrophages had a similar, but delayed kinetic profile to the neutrophils (Figures 6b versus 5b), with a peak around 48-72 h preceding a decline by 96 h; in GM-CSFÀ/À mice, as for the neutrophils (Figure 5b), the Ly6C hi macrophage numbers declined earlier (Figure 6b). For the wild-type mice, the later macrophage response (around 72-96 h; Figure 5a) is in fact characterized by the appearance of Ly6C lo macrophages (Figure 6c), as found before in the thioglycolate-elicited model, 39 which did not occur in the gene-deficient mice (Figure 6c).…”

“…Peritoneal macrophage subpopulations were next examined, again using Ly6C expression. As before, 39 in wild-type mice, the resident macrophages were Ly6C lo and were replaced by exudate macrophages, which initially were Ly6C hi , but then were Ly6C lo , as the mBSA-induced peritoneal inflammation proceeded (Figure 6a). It can be seen that this transition from Ly6C hi to Ly6C lo expression was gradual rather than being abrupt, indicating perhaps local conversion rather than separate trafficking kinetics being responsible (see Discussion).…”

“…thioglycolate injection, that immature Ly6C hi macrophages were observed early in the exudate to be replaced by Ly6C lo macrophages. 39 To be able to compare directly in the same experiment the involvement of CSF-1R and GM-CSF on macrophage lineage populations in an inflammation model, we chose mBSA-dependent acute peritonitis established in our laboratory, 31 as unlike the widely used thioglycolate-induced peritonitis model, we had shown that the maintenance of the inflammatory reaction was GM-CSF-dependent. 30 Also, an antigen-driven model would serve as a useful one for immune-driven inflammation models in general.…”

Treatment of arthritis by macrophage depletion and immunomodulation: Testing an apoptosis‐mediated therapy in a humanized death receptor mouse model

“…Ly-6C is a monocyte/macrophage differentiation antigen regulated by IFN␥ (39), which has been shown to facilitate apoptosis signaling in macrophages and cancer cells (40,41). Inflammatory macrophages express much higher levels of Ly-6C compared with "those residing normally in tissues" (42). In CIA and K/BxN mouse serum transferinduced arthritis, a reduction in the number of Ly-6Cpositive synovial macrophages has been associated with granulocyte-macrophage colony-stimulating factor (GM-CSF) blockade and reduced disease severity (43), suggesting that Ly-6C high macrophages are associated with a GM-CSF-mediated arthritis response.…”

Flow cytometric isolation and phenotypic characterization of two subsets of ED2+ (CD163) hepatic macrophages in rats

“…The ED2 dim /AF high cells were found expression of ERMP-12 (CD31) and ERMP-20 (Ly-6C) which are genes associated with early myeloid lineage development. 33,34 There was also differential expression of inflammatory cytokine (IL-1b, CCL5, TNF-a), ECM remodeling enzymes (TIMP-1, MMP-9) and fucose receptor by these two ED2 + subsets in normal livers, indicating functional differences between the ED2 dim /AF dim and ED2 high /AF high liver macrophages.…”