Phosphorylated TDP-43 localizes to chronic cerebral infarctions in human brains.

The transactivation response DNA-binding protein of 43 kDa (TDP-43) is a nuclear protein pivotal in RNA processing. Because phosphorylated TDP43 (pTDP-43) has been identified as a component of the ubiquitin-positive and tau-negative inclusions observed in the brains of frontotemporal lobar degeneration (FTLD) and amyotrophic lateral sclerosis (ALS) patients, it is considered to play a major role in neurodegenerative processes. We previously reported that pTDP-43 is located in macrophages of atherosclerotic lesions of human carotid and major cerebral arteries. We hence hypothesized that pTDP-43 might be localized in the macrophages of other human brain lesions. Therefore, we investigated the immunolocalization of pTDP-43 in human brains with chronic cerebral infarction. Furthermore, we investigated the colocalization of pTDP-43 and the 14-3-3 eta isoform and found that pTDP-43 was localized in many macrophages located in chronic cerebral infarctions, in 6 out of the 15 human brains analyzed. pTDP-43 colocalized with the 14-3-3 eta isoform in these lesions. This is the first demonstration of pTDP-43 immunolocalization in chronic cerebral infarctions in human brains. We believe that our findings may be useful towards further understanding the pathophysiological roles of TDP-43 in various neurological disorders.