Accumulation of plasma proteins in Purkinje cells as an indicator of blood-brain barrier breakdown

Tau protein (MAPT) as a possible biochemical marker of traumatic brain injury in postmortem examination

MAPT is a neuronal protein that plays an important role in axonal stabilization, neuronal development, and neuronal polarity. MAPT release into the CSF and blood has been interpreted as indicative of axonal injury as its elevated levels were observed in olympic boxers even after a mild head trauma suggesting minor CNS injuries. In our study we wanted to check the potential relevance of MAPT examination for forensic purposes. The study was carried out using cases of head injury group and cases of sudden death (cardiopulmonary failure, no injuries of the head - control group) provided by forensic pathologists at the Department of Forensic Medicine, Medical University of Warsaw. CSF and blood were collected within 24h after death using suboccipital puncture and femoral vein puncture. Serum and cerebrospinal fluid Tau protein concentrations were compared using an enzyme-linked immunosorbent assay (elisa). Brain specimens (frontal cortex) were collected during forensic autopsies. Sections were stained histologically (hematoxylin-eosin) and immunohistochemically with anti human Tau antibody, anti glial fibrillary acid protein (GFAP), anti human macrosialin (CD68) or anti human endothelial cells (CD34). In our study we documented that elevated levels of serum and CSF MAPT may also be considered a marker for mild traumatic brain injury and traumatic brain injury (mTBI and TBI). An increase in CSF and serum levels of MAPT in the absence of visible macroscopic traumatic CNS changes indicates that even minor head injuries may result in changes at the neuronal level that could remain undiagnosed during regular forensic autopsy and routine histopathological examination.

Evidence That Cingulin Regulates Endothelial Barrier Function In Vitro and In Vivo

OBJECTIVE

Cingulin is a cytoplasmic component of tight junctions. Although modulation of cingulin levels in cultured epithelial model systems has no significant effect on barrier function, evidence from cingulin knockout mice suggests that cingulin may be involved in the regulation of the behavior of epithelial or endothelial cells. Here, we investigate the role of cingulin in the barrier function of endothelial cells.

APPROACH AND RESULTS

We show that cingulin is expressed in human endothelial cells of the skin, brain, and lung in vivo and in vitro. Endothelial cingulin colocalizes and coimmunoprecipitates with the tight junction proteins zonula occludens-1 and guanine nucleotide exchange factor-H1. Cingulin overexpression in human umbilical vein endothelial cell induces tight junction formation, increases transendothelial electric resistance, and strengthens barrier function for low and high molecular weight tracers. In contrast, cultured endothelial cells lacking cingulin are more permeable for low molecular weight tracers. In cingulin knockout mice, neurons of the area postrema and Purkinje cells show an increased uptake of small molecular weight tracers indicating decreased barrier function at these sites.

CONCLUSIONS

We demonstrate that cingulin participates in the modulation of endothelial barrier function both in human cultured cells in vitro and in mouse brains in vivo. Understanding the role of cingulin in maintaining tight barriers in endothelia may allow developing new strategies for the treatment of vascular leak syndromes.

CADASIL and CARASIL

CADASIL and CARASIL are hereditary small vessel diseases leading to vascular dementia. CADASIL commonly begins with migraine followed by minor strokes in mid-adulthood. Dominantly inherited CADASIL is caused by mutations (n > 230) in NOTCH3 gene, which encodes Notch3 receptor expressed in vascular smooth muscle cells (VSMC). Notch3 extracellular domain (N3ECD) accumulates in arterial walls followed by VSMC degeneration and subsequent fibrosis and stenosis of arterioles, predominantly in cerebral white matter, where characteristic ischemic MRI changes and lacunar infarcts emerge. The likely pathogenesis of CADASIL is toxic gain of function related to mutation-induced unpaired cysteine in N3ECD. Definite diagnosis is made by molecular genetics but is also possible by electron microscopic demonstration of pathognomonic granular osmiophilic material at VSMCs or by positive immunohistochemistry for N3ECD in dermal arteries. In rare, recessively inherited CARASIL the clinical picture and white matter changes are similar as in CADASIL, but cognitive decline begins earlier. In addition, gait disturbance, low back pain and alopecia are characteristic features. CARASIL is caused by mutations (presently n = 10) in high-temperature requirement. A serine peptidase 1 (HTRA1) gene, which result in reduced function of HTRA1 as repressor of transforming growth factor-β (TGF β) -signaling. Cerebral arteries show loss of VSMCs and marked hyalinosis, but not stenosis.