TY - JOUR
T1 - Early influx of macrophages determines susceptibility to experimental allergic encephalomyelitis in Dark Agouti (DA) rats
AU - Mensah-Brown, Eric P.
AU - Shahin, Allen
AU - Al Shamisi, Mariam
AU - Lukic, Miodrag L.
N1 - Funding Information:
The work was supported by grants from FMHS and UAEU to EPK Mensah-Brown and ML Lukic. The authors are grateful for the contributions of Salama Mohamed Ali Al Housani and Essa Mohammed Ali Abdulla Al Eassa, both students of FMHS who undertook parts of this work as summer projects.
PY - 2011/3
Y1 - 2011/3
N2 - Experimental allergic encephalomyelitis (EAE) is characterized by inflammatory infiltrates of myelin antigen(s) specific T cells and consecutive demyelination. Injection of encephalitogen into the footpads induces disease in genetically susceptible Dark Agouti rats (DA) but not in Albino Oxford (AO) rats although mild inflammatory infiltrates are observed in both strains early after disease induction. In addition, only DA rats develop disease when cells from (AO×DA) F1 hybrids are passively transferred into sub-lethally radiated AO and DA parent hosts. The aim of the study was therefore to examine the participation of accessory cells, macrophages, dendritic cells and microglia in EAE development at the level of the target tissue in these two strains using specific membrane markers. We demonstrate here that in the induction phase of EAE in DA rats, macrophages (CD68+; CD45hiCD11b+) are the first detectable infiltrating cells in the subpial regions of the spinal cord but were not found in AO rats. During the same period, resident microglial cells which are of the ramified variety are observed in both DA and AO rats. In DA rats at the peak of disease, when profuse influx of T cells is seen, macrophages and dendritic cells appear in the parenchyma of the CNS. In addition, at that time, microglial cells are activated. FACS analyses also reveal a significant increase in CD45hiCD11c+ dendritic cells and CD45hiD11b+ macrophages compared with levels in naïve and immunized AO rats. During resolution of disease in DA rats, the expression of microglia and macrophage markers is comparable with those in naïve non-immunized DA and immunized AO rats. We conclude that an initial influx of macrophages is indispensible for the development of EAE in DA rats. The presence of dendritic cells and myeloid dendritic cells at the peak of disease supports the role of these cells in EAE especially in relapses and chronicity. The activation pattern of microglia in DA rats does not indicate their role as antigen presenting cells in disease induction since they are ramified at the induction phase and only become activated after the overwhelming influx of T cells.
AB - Experimental allergic encephalomyelitis (EAE) is characterized by inflammatory infiltrates of myelin antigen(s) specific T cells and consecutive demyelination. Injection of encephalitogen into the footpads induces disease in genetically susceptible Dark Agouti rats (DA) but not in Albino Oxford (AO) rats although mild inflammatory infiltrates are observed in both strains early after disease induction. In addition, only DA rats develop disease when cells from (AO×DA) F1 hybrids are passively transferred into sub-lethally radiated AO and DA parent hosts. The aim of the study was therefore to examine the participation of accessory cells, macrophages, dendritic cells and microglia in EAE development at the level of the target tissue in these two strains using specific membrane markers. We demonstrate here that in the induction phase of EAE in DA rats, macrophages (CD68+; CD45hiCD11b+) are the first detectable infiltrating cells in the subpial regions of the spinal cord but were not found in AO rats. During the same period, resident microglial cells which are of the ramified variety are observed in both DA and AO rats. In DA rats at the peak of disease, when profuse influx of T cells is seen, macrophages and dendritic cells appear in the parenchyma of the CNS. In addition, at that time, microglial cells are activated. FACS analyses also reveal a significant increase in CD45hiCD11c+ dendritic cells and CD45hiD11b+ macrophages compared with levels in naïve and immunized AO rats. During resolution of disease in DA rats, the expression of microglia and macrophage markers is comparable with those in naïve non-immunized DA and immunized AO rats. We conclude that an initial influx of macrophages is indispensible for the development of EAE in DA rats. The presence of dendritic cells and myeloid dendritic cells at the peak of disease supports the role of these cells in EAE especially in relapses and chronicity. The activation pattern of microglia in DA rats does not indicate their role as antigen presenting cells in disease induction since they are ramified at the induction phase and only become activated after the overwhelming influx of T cells.
KW - Apoptosis
KW - Encephalitogen
KW - Macrophages
KW - Microglia
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U2 - 10.1016/j.jneuroim.2010.10.010
DO - 10.1016/j.jneuroim.2010.10.010
M3 - Article
C2 - 21109309
AN - SCOPUS:79952252910
SN - 0165-5728
VL - 232
SP - 68
EP - 74
JO - Journal of Neuroimmunology
JF - Journal of Neuroimmunology
IS - 1-2
ER -