Neuropathological characterization of a novel TANK binding kinase (TBK1) gene loss of function mutation associated with amyotrophic lateral sclerosis.

AIMS: Mutations in TANK binding kinase gene (TBK1) are causative in amyotrophic lateral sclerosis (ALS), however correlations between clinical features and TBK1 mutations have not been fully elucidated. We aimed to identify and compare TBK1 mutations to clinical features in a cohort of ALS patients from Northern England. METHODS: TBK1 mutations were analysed in 290 ALS cases. Immunohistochemistry was performed in brain and spinal cord of one case with a novel in-frame deletion. RESULTS: Seven TBK1 variants were identified, including one novel in-frame deletion (p.85delIle). In silico analysis and literature suggested four variants were pathogenic, and three were variants of uncertain significance or benign. Post-mortem immunohistochemistry established an individual with the novel in-frame deletion had classical ALS and Type B FTLD-TDP pathology, with no changes in TBK1 staining or interferon regulatory factor IRF3. CONCLUSIONS: TBK1 mutations were present in 1.38% of our cohort, and screening showed no clear genotype-phenotype associations compared to other genetic and sporadic ALS cases. TBK1 immunohistochemistry was consistent with previously published literature and we are the first to show no differential expression of interferon regulatory factor IRF3, a downstream effector of TBK1 in the immune pathway, in the TBK1-mutant tissue, compared to controls.

Expression microdissection isolation of enriched cell populations from archival brain tissue.

BACKGROUND: Laser capture microdissection (LCM) is an established technique for the procurement of enriched cell populations that can undergo further downstream analysis, although it does have limitations. Expression microdissection (xMD) is a new technique that begins to address these pitfalls, such as operator dependence and contamination. NEW METHOD: xMD utilises immunohistochemistry in conjunction with a chromogen to isolate specific cell types by extending the fundamental principles of LCM to create an operator-independent method for the procurement of specific CNS cell types. RESULTS: We report how xMD enables the isolation of specific cell populations, namely neurones and astrocytes, from rat formalin fixed-paraffin embedded (FFPE) tissue. Subsequent reverse transcriptase-polymerase chain reaction (RT-PCR) analysis confirms the enrichment of these specific populations. RIN values after xMD indicate samples are sufficient to carry out further analysis. COMPARISON WITH EXISTING METHOD: xMD offers a rapid method of isolating specific CNS cell types without the need for identification by an operator, reducing the amount of unintentional contamination caused by operator error, whilst also significantly reducing the time required by the current basic LCM technique. CONCLUSIONS: xMD is a superior method for the procurement of enriched cell populations from post-mortem tissue, which can be utilised to create transcriptome profiles, aiding our understanding of the contribution of these cells to a range of neurological diseases. xMD also addresses the issues associated with LCM, such as reliance on an operator to identify target cells, which can cause contamination, as well as addressing the time consuming nature of LCM.

Orexin-A, an hypothalamic peptide with analgesic properties.

The hypothalamic peptide orexin-A and the orexin-1 receptor are localized in areas of the brain and spinal cord associated with nociceptive processing. In the present study, localization was confirmed in the spinal cord and demonstrated in the dorsal root ganglion for both orexin-A and the orexin-1 receptor. The link with nociception was extended when orexin-A was shown to be analgesic when given i.v. but not s.c. in mouse and rat models of nociception and hyperalgesia. The efficacy of orexin-A was similar to that of morphine in the 50 degrees C hotplate test and the carrageenan-induced thermal hyperalgesia test. However, involvement of the opiate system in these effects was ruled out as they were blocked by the orexin-1 receptor antagonist SB-334867 but not naloxone. Orexin-1 receptor antagonists had no effect in acute nociceptive tests but under particular inflammatory conditions were pro-hyperalgesic, suggesting a tonic inhibitory orexin drive in these circumstances. These data demonstrate that the orexinergic system has a potential role in the modulation of nociceptive transmission.