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Introduction Frontotemporal lobar degeneration ( FTLD) is classified mainly into FTLD-tau and FTLD- TDP according to the protein present within inclusion bodies. While such a classification implies only a single type of protein should be present, recent studies have demonstrated dual tau and TDP-43 proteinopathy can occur, particularly in inherited FTLD. Methods We therefore investigated 33 patients with FTLD-tau (including 9 with MAPT mutation) for TDP-43 pathological changes, and 45 patients with FTLD- TDP (including 12 with hexanucleotide expansion in C9ORF72 and 12 with GRN mutation), and 23 patients with motor neurone disease (3 with hexanucleotide expansion in C9ORF72), for tauopathy. Results TDP-43 pathological changes, of the kind seen in many elderly individuals with Alzheimer's disease, were seen in only two FTLD-tau cases - a 70-year-old male with exon 10 + 13 mutation in MAPT, and a 73-year-old female with corticobasal degeneration. Such changes were considered to be secondary and probably reflective of advanced age. Conversely, there was generally only scant tau pathology, usually only within hippocampus and/or entorhinal cortex, in most patients with FTLD- TDP or MND. The extent of tau pathology in FTLD- TDP and MND, as with amyloid β protein, may relate to increased age and possession of Apolipoprotein ε4 allele. Conclusion We find no predilection or predisposition towards an accompanying TDP-43 pathology in patients with FTLD-tau, irrespective of presence or absence of MAPT mutation, or that genetic changes associated with FTLD- TDP predispose towards excessive tauopathy. Where the two processes coexist, this is limited and probably causatively independent of each other. [ABSTRACT FROM AUTHOR]

Aims Pathological heterogeneity within patients with frontotemporal lobar degeneration ( FTLD) in general precludes the accurate assignment of diagnostic subtype in life. The aim of this study was to assess the extent of microglial cell activation in FTLD in order to determine whether it might be possible to employ this as a diagnostic marker in vivo using PET ligand [11 C]( R)- PK11195 in order to differentiate cases of FTLD according to histological subtype. Methods The distribution and extent of microglial cell activation was assessed semi-quantitatively in cortical grey and subcortical white matter of CD68 immunostained sections of frontal and temporal cortex from 78 pathologically confirmed cases of FTLD, 13 of Alzheimer's disease ( AD) and 13 controls. Results Significantly higher levels of microglial cell activation than controls occurred in all four regions in FTLD, and in three of the four regions in AD. Microglial activation was greater in frontal subcortical white matter in FTLD than AD, whereas it was higher in temporal cortical grey matter in AD than FTLD. Microglial cell activation was significantly higher in temporal subcortical white matter in FTLD- MAPT than in other genetic ( GRN, C9ORF 72) or non-genetic forms of FTLD. Conclusions The present study suggests that high levels of microglial cell involvement in temporal lobe (subcortical white matter) might serve as a marker of inherited FTLD associated with intronic mutations in MAPT, with a relatively intense signal in this region in PET studies using [11 C]( R)- PK11195 as microglial cell marker could indicate the presence of MAPT mutation in vivo. [ABSTRACT FROM AUTHOR]

Aims Frontotemporal lobar degeneration ( FTLD) and motor neurone disease are linked by the possession of a hexanucleotide repeat expansion in C9ORF72, and both show neuronal cytoplasmic inclusions within cerebellar and hippocampal neurones which are TDP-43 negative but immunoreactive for p62 and dipeptide repeat proteins ( DPR), these being generated by a non- ATG RAN translation of the expanded region of the gene. Methods Twenty-two cases of FTLD from Newcastle were analysed for an expansion in C9ORF72 by repeat primed PCR and Southern blot. Detailed case note analysis was performed, and blinded retrospective clinical impressions were achieved by review of clinical histories. Sections from all major brain regions were immunostained for TDP-43, p62 and DPR. The extent of TDP-43 and DPR pathology in expansion bearers was compared with that in 13 other previously identified cases from the Manchester Brain Bank with established disease. Results Three Newcastle patients bearing an expansion in C9ORF72 were identified. These three patients died prematurely, two from bronchopneumonia within 10 months and 3 years of onset, and one from myocardial infarction 3 years after onset. In all three, DPR were plentiful throughout all cerebral cortical regions, hippocampus and cerebellum, but TDP-43 pathological changes were sparse. The severity of DPR pathological changes in these three patients was similar to that in the Manchester series, although the extent of TDP-43 pathology was significantly less. Conclusion Widespread accumulation of DPR within nerve cells may occur much earlier than that of TDP-43 in patients with FTLD bearing expansion in C9ORF72. [ABSTRACT FROM AUTHOR]

Aims Frontotemporal lobar degeneration ( FTLD) is clinically and pathologically heterogeneous. Although associated with variations in MAPT, GRN and C9ORF72, the pathogenesis of these, and of other nongenetic, forms of FTLD, remains unknown. Epigenetic factors such as histone regulation by histone deacetylases ( HDAC) may play a role in the dysregulation of transcriptional activity, thought to underpin the neurodegenerative process. Methods The distribution and intensity of HDACs 4, 5 and 6 was assessed semi-quantitatively in immunostained sections of temporal cortex with hippocampus, and cerebellum, from 33 pathologically confirmed cases of FTLD and 27 controls. Results We found a significantly greater intensity of cytoplasmic immunostaining for HDAC4 and HDAC6 in granule cells of the dentate gyrus in cases of FTLD overall compared with controls, and specifically in cases of FTLD tau- Picks compared with FTLD tau- MAPT and controls. No differences were noted between FTLD- TDP subtypes, or between the different genetic and nongenetic forms of FTLD. No changes were seen in HDAC5 in any FTLD or control cases. Conclusions Dysregulation of HDAC4 and/or HDAC6 could play a role in the pathogenesis of FTLD-tau associated with Pick bodies, although their lack of immunostaining implies that such changes do not contribute directly to the formation of Pick bodies. [ABSTRACT FROM AUTHOR]