Turnover of bone marrow‐derived cells in the irradiated mouse cornea

Abstract

Summary In light of an increasing awareness of the presence of bone marrow (BM)‐derived macrophages in the normal cornea and their uncertain role in corneal diseases, it is important that the turnover rate of these resident immune cells be established. The baseline density and distribution of macrophages in the corneal stroma was investigated in Cx3cr1gfp transgenic mice in which all monocyte‐derived cells express enhanced green fluorescent protein (eGFP). To quantify turnover, BM‐derived cells from transgenic eGFP mice were transplanted into whole‐body irradiated wild‐type recipients. Additionally, wild‐type BM‐derived cells were injected into irradiated Cx3cr1+/gfp recipients, creating reverse chimeras. At 2, 4 and 8 weeks post‐reconstitution, the number of eGFP+ cells in each corneal whole mount was calculated using epifluorescence microscopy, immunofluorescence staining and confocal microscopy. The total density of myeloid‐derived cells in the normal Cx3cr1+/gfp cornea was 366 cells/mm2. In BM chimeras 2 weeks post‐reconstitution, 24% of the myeloid‐derived cells had been replenished and were predominantly located in the anterior stroma. By 8 weeks post‐reconstitution 75% of the myeloid‐derived cells had been replaced and these cells were distributed uniformly throughout the stroma. All donor eGFP+ cells expressed low to moderate levels of CD45 and CD11b, with approximately 25% coexpressing major histocompatibility complex class II, a phenotype characteristic of previous descriptions of corneal stromal macrophages. In conclusion, 75% of the myeloid‐derived cells in the mouse corneal stroma are replenished after 8 weeks. These data provide a strong basis for functional investigations of the role of resident stromal macrophages versus non‐haematopoietic cells using BM chimeric mice in models of corneal inflammation.

Resident macrophages in the cochlear blood-labyrinth barrier and their renewal via migration of bone-marrow-derived cells

“…Tissue PVMs are renewed by the recruitment of bloodborne monocytes (Xu et al 2007;Chinnery et al 2008). For Fig.…”

“…They have been shown to express CD45, CD11b, MOMA2, MHC-II, F4/80 (Xu et al 2007;Chinnery et al 2008), the hemoglobin-haptoglobin scavenger receptor CD163, and the mannose receptor CD206 (Kim et al 2006;Mitrasinovic et al 2005). Under physiological conditions, PVMs have a long residence period (Chan-Ling et al 2006;Sengupta et al 2003).…”

Herpesvirus Entry Mediator and Ocular Herpesvirus Infection: More than Meets the Eye

“…The shift in HVEMpositive (HVEM ϩ ) populations likely reflects differences in the cellular composition of the ocular infiltrate over time rather than fluctuations in HVEM expression, although this was not directly tested in our study. Stromal macrophages (and DCs) incompletely turn over with irradiation (93); therefore, these could be the radiation-resistant HVEM ϩ cell type identified as mediating disease in adoptive-transfer experiments (44). Although other HVEM ϩ lineages may also contribute to pathogenesis, albeit in a subtler fashion, monocytes/macrophages are particularly intriguing to us in light of these findings.…”

Protective effects of matrix metalloproteinase-12 following corneal injury

“…Sources of MMP12 in the cornea following injury include resident corneal macrophages and macrophages recruited from the peripheral circulation (Brissette-Storkus et al, 2002;Chinnery et al, 2008;Hamrah et al, 2003). To determine the contribution of MMP12 produced by peripheral macrophages to corneal angiogenesis following injury, we reciprocally transplanted bone marrow cells from Mmp12 2/2 mice and WT mice into recipient mice that were lethally irradiated to generate bone marrow chimeric mice.…”