Density of TMEM119-positive microglial cells in postmortem cerebrospinal fluid as a surrogate marker for assessing complex neuropathological processes in the CNS

TMEM119-positive microglial cells in cerebrospinal fluid, a potential new marker for neuroinflammatory response after aneurysmal subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (aSAH) is a debilitating condition with significant morbidity and mortality rates. Despite advancements in treatment, understanding the underlying pathophysiology, particularly the inflammatory response, remains crucial for improving patient outcomes. In this study, we investigated the presence of transmembrane protein 119 (TMEM119) of microglial cells in cerebrospinal fluid (CSF) as a potential marker for neuroinflammation following aSAH. CSF samples were collected from aSAH patients, pathological and healthy controls, processed, and analyzed using immunocytochemistry. TMEM119-positive microglial cells were consistently identified in the CSF of aSAH patients, exhibiting amoeboid morphology and intense staining. Importantly, microglial cells were detected as early as the first day post-bleeding, persisting throughout the acute phase in some cases. Analysis of consecutive samples revealed varying trends in microglial cell numbers, with a peak during the initial phase followed by a gradual decline. Our findings suggest that microglia may migrate into the CSF following aSAH, potentially serving as an early predictor of inflammatory-related CNS damage. This study underscores the importance of understanding neuroinflammatory processes in aSAH and opens avenues for further research on the role of microglia in CNS disorders by liquid biopsy.

The polychromatism of postmortem cerebrospinal fluid

Based on the assumption that postmortem cerebrospinal fluid (CSF) is contaminated depending on the chosen sampling technique in the forensic setting resulting in bloody or at least hemolytic CSF samples, we systematically documented a total of 183 postmortem CSF samples. These samples were all assessed for their quality and color, regardless of the cause of death or the postmortem interval. The investigations were carried out through subjective assessment of color and turbidity, as well as objective measurements of the optical density (OD) of the CSF supernatants after centrifugation of each sample, with standardized photographic documentation. The observations revealed that in 28 cases the CSF was absolutely (crystal-) clear and transparent. Most of our samples showed color changes ranging from xanthrochromic to rose. Intensive staining of the supernatants was only found in a small proportion of the examined collective. We found that postmortem CSF has no uniform appearance but rather a diverse range of color spectra, and the color, as well as the OD of the CSF, correlates significantly with the postmortem interval (p < 0.001) when sampled using the proposed standard procedure.

Multiorgan immunohistochemical endothelial expression of E-selectin in a forensic case of sepsis

Sepsis is one of the major threats for the survival and prognosis of patients in intensive care units. In cases where detailed clinical data and monitoring is available, the diagnosis of sepsis is reliable. But when clinical data are incomplete or missing and sepsis is only suspected based on the autopsy results, the picture is often equivocal. This report describes the gross pathological findings obtained from the autopsy of a 48-year-old woman with Crohn's disease after surgical intervention. Macroscopically, we found intestinal perforation and signs of peritonitis. Histologically, the pulmonary/bronchial arteries were lined with E-selectin (CD 62E)-positive endothelial cells, which are an established postmortem histological marker of sepsis. We extended our investigations to the cerebral cortex and subcortical medullary layer. The endothelium of the cortical vessels and those in the cerebral medullary layer were likewise immunopositive for E-selectin. Furthermore, numerous TMEM119-positive, highly ramified microglial cell profiles were found in the grey and white matter. Microglial cells were lining the vascular profiles. In addition, TMEM119-positive microglial profiles were abundant in the cerebrospinal fluid (CSF). Multiorgan E-selectin positivity of the vascular endothelia provides further evidence for the postmortem diagnosis of sepsis.

The Role of Protein Degradation in Estimation Postmortem Interval and Confirmation of Cause of Death in Forensic Pathology: A Literature Review

It is well known that proteins are important bio-macromolecules in human organisms, and numerous proteins are widely used in the clinical practice, whereas their application in forensic science is currently limited. This limitation is mainly attributed to the postmortem degradation of targeted proteins, which can significantly impact final conclusions. In the last decade, numerous methods have been established to detect the protein from a forensic perspective, and some of the postmortem proteins have been applied in forensic practice. To better understand the emerging issues and challenges in postmortem proteins, we have reviewed the current application of protein technologies at postmortem in forensic practice. Meanwhile, we discuss the application of proteins in identifying the cause of death, and postmortem interval (PMI). Finally, we highlight the interpretability and limitations of postmortem protein challenges. We believe that utilizing the multi-omics method can enhance the comprehensiveness of applying proteins in forensic practice.