Microglial activation in multiple system atrophy: a potential role for NF-kappaB/rel proteins.

Microglial activation is a prominent feature of affected brain areas in multiple system atrophy. Microglia express proinflammatory peptides, which may be a result of activation of nuclear factor-KB. We investigated the nuclear presence of RelA, the 65 kDa subunit of the NF-KB/RelA family in striatum and brain stem of patients with multiple system atrophy. Affected brain areas of patients with multiple system atrophy showed a marked immunoreactivity for nuclear Rel A p65, which was almost exclusively localized in activated microglia. Interestingly nuclear translocation of Rel A was not detected in striatal tissue of controls and Parkinson disease patients. Thus, NF-kappaB/Rel A complexes may play a role in mediating microglial activation in multiple system atrophy.

Effects of macrophage migration inhibitory factor and macrophage migration stimulatory factor on function and survival of foetal dopaminergic grafts in the 6-hydroxydopamine rat model of Parkinson's disease.

Activated microglia play an important role in the rejection of intracerebral grafts and the degeneration of axotomized neurones. We studied the effect of macrophage migration stimulatory factor (MSF) or macrophage migration inhibitory factor (MIF) on allogeneic foetal mesencephalic dopaminergic grafts transplanted into the striatum of 6-hydroxydopamine-lesioned rats. Rotation testing revealed a significant compensation of lesion-induced motor asymmetry 3 weeks post-grafting in animals treated with MIF and vehicle-treated controls compared with pre-graft values (Student's t-test, P < or = 0.005) and MSF-treated animals (ANOVA, post hoc Fisher PLSD test, P < or = 0.05). The MSF group showed no significant compensation. Graft recipients with MIF application (1452.06 +/- 164.32 tyrosine hydroxylase-positive ventral mesencephalic cells) and controls (1753.21 +/- 165.51 tyrosine hydroxylase-positive neurones) displayed good graft survival. Animals with MSF application showed a significant reduction of tyrosine hydroxylase-positive grafted cells (MSF 570.36 +/- 209.49 cells) and graft volumes compared with the MIF and the control group (ANOVA, post hoc Fisher PLSD test, P < or = 0.05). The proportional area of microglia was significantly reduced in MIF animals compared with control animals (ANOVA, post hoc Fisher PLSD test, P < or = 0.001). Activated microglia and macrophages were reduced by half in the MIF-treated group compared with MSF animals and controls. We conclude that intrastriatal injections of MSF result in impaired function and survival of allogeneic ventral mesencephalon (VM) grafts 3 weeks after transplantation. MIF can reduce the number of microglia and macrophages in allogeneic foetal VM grafts. A reduction of microglia via MIF application did not enhance graft function and survival.

Effects of graft pooling of foetal rat and mouse tissue and immunosuppression in the 6-hydroxydopamine rat model of Parkinson's disease.

We employed intracerebral co-transplantation of foetal xenogeneic striatal mouse tissue and allogeneic rat substantia nigra into the adult rat brain to elucidate the effects of xenogeneic mouse graft on the function and survival of an allogeneic rat graft in 6-hydroxydopamine lesioned Sprague-Dawley rats. Foetal mouse striatum (STR) and rat substantia nigra (VM) were transplanted as non-pooled separate deposits or a pooled cell suspension with or without cyclosporin A (Cy A). Immunosuppressed recipients of pooled rat and mouse co-grafts showed a significantly better compensation of amphetamine-induced rotational behaviour compared with non-immunosuppressed animals with pooled rat and mouse co-grafts 3 and 6 weeks post-grafting. Tyrosine hydroxylase (TH) immunohistochemistry revealed a non-significant reduction in survival in pooled (1806.3+/-367.5 cells) rat and mouse co-transplants without immunosuppression compared with immunosuppressed pooled (3383.3+/-732.7 cells) animals with allo- and xenogeneic tissue and controls (3506.4+/-839.3 cells). Graft volumes were significantly reduced in pooled transplants without immunosuppression (0.1+/-0.026 mm3; ANOVA post-hoc Scheffe F-test, P<0.0001) compared with immunosuppressed recipients (0.7+/-0.1 mm3) and controls (0.6+/-0.1 mm3). In non-pooled allo- and xenogeneic grafts without immunosuppression the survival rate of the TH-immunoreactive cells and graft volumes were reduced (2359.3+/-479.5 cells; 0.2+/-0.043 mm3) compared with immunosuppressed animals (2927.3+/-946.6 cells; 0.6+/-0.2 mm3) and controls (2701.1+/-693.8 cells; 0.3+/-0.1 mm3) without reaching a level of significance. Rejection of mouse tissue was observed in all non-immunosuppressed recipients. In summary: (i) continued immunosuppression yielded significant beneficial effects on function and beneficial effects on survival of pooled grafts with an immunogenetic disparity; (ii) the rejection of a xenogeneic graft component may compromise survival and function of other, allogeneic graft components; and (iii) transplantation of non-pooled allo- and xenogeneic tissues may result in a better survival of the graft compared with pooled cell suspensions.

Cellular immune reactions in brain transplantation: effects of graft pooling and immunosuppression in the 6-hydroxydopamine rat model of Parkinson's disease.

We used high immunogenic mouse and low immunogenic rat brain transplants to investigate the effect of pooling of tissue with immunogenetic disparity on cellular immune reactions. Foetal xenogenic mouse striatum and allogenic rat substantia nigra were implanted into i) the 6-hydroxydopamine lesioned striatum of outbred female Sprague-Dawley rats as a pooled cell suspension, or into ii) the unlesioned and lesioned striata as non-pooled separate deposits, with or without immunosuppressive treatment with cyclosporin A (Cy A). In control animals, iii) mouse striatum was replaced by rat striatum, and iv) sham grafts with and without immunosuppression. Six weeks post grafting, brains were semiquantitatively processed using immunocytochemical markers for microglia, astrocytes, T-helper cells, and macrophages, major histocompatibility class (MHC) I and II expression. The total amount of immunoreactivity (PA) for microglial cells and astrocytes was pronounced and the PA for T-helper cells and macrophages was doubled in recipients of pooled rat and mouse cografts compared to non-pooled deposits, indicating ongoing immune reactions with participation of glial cells. MHC I expression was significantly increased in pooled xeno- and allogenic cografts with and without immunosuppression compared to allogenic controls. Expression of MHC II was significantly increased in pooled cografts without immunosuppression. In recipients of separate, non-pooled heteroimmunogenic cotransplants, MHC I and II expression was significantly increased in xenogenic deposits with and without immunosuppression. MHC II was as well significantly increased in allogenic deposits without immunosuppression. Immunosuppressed animals with non-pooled allogenic mouse cografts showed low levels of cellular immune parameters. In conclusion non-pooled heteroimmunogenic grafts lead to less pronounced immune reactions compared to pooled grafts and immunosuppressive treatment with Cy A has a beneficial effect on acute transplant-associated immune parameters.