Human Herpesvirus 8-Positive Multicentric Castleman Disease in an Immunocompetent Patient: A Diagnostic Challenge.

We present a clinical case of a 79-year-old male admitted to inpatient care for longstanding asthenia and respiratory symptoms. Associated features were polyserositis, multiple enlarged lymphatic nodules, acute kidney injury, and heart failure. The patient's recent medical history revealed SARS-CoV-2 vaccination a week prior and an upper respiratory tract infection. The laboratory results from thoracentesis were compatible with a transudate, with no immunological stain. Epstein-Barr virus polymerase chain reaction (PCR) was positive. The thoracic, abdominal, and pelvic CT scans revealed multiple enlarged lymphatic nodules, worsening the pre-existent polyserositis and hepatosplenomegaly. The patient began to show signs of neurologic symptoms and deterioration of the global health status. An enlarged lymphatic nodule was excised and the pathology showed human herpesvirus 8 multicentric Castleman disease. The disease evolved rapidly into hematological dysfunction and blood transfusions were necessary. Even though the patient was started on high-dose rituximab therapy combined with etoposide, the disease evolved into multiorgan dysfunction with a fatal outcome.

Neuronal inclusions of α-synuclein contribute to the pathogenesis of Krabbe disease.

Demyelination is a major contributor to the general decay of neural functions in children with Krabbe disease. However, recent reports have indicated a significant involvement of neurons and axons in the neuropathology of the disease. In this study, we have investigated the nature of cellular inclusions in the Krabbe brain. Brain samples from the twitcher mouse model for Krabbe disease and from patients affected with the infantile and late-onset forms of the disease were examined for the presence of neuronal inclusions. Our experiments demonstrated the presence of cytoplasmic aggregates of thioflavin-S-reactive material in both human and murine mutant brains. Most of these inclusions were associated with neurons. A few inclusions were detected to be associated with microglia and none were associated with astrocytes or oligodendrocytes. Thioflavin-S-reactive inclusions increased in abundance, paralleling the development of neurological symptoms, and distributed throughout the twitcher brain in areas of major involvement in cognition and motor functions. Electron microscopy confirmed the presence of aggregates of stereotypic ß-sheet folded proteinaceous material. Immunochemical analyses identified the presence of aggregated forms of α-synuclein and ubiquitin, proteins involved in the formation of Lewy bodies in Parkinson's disease and other neurodegenerative conditions. In vitro assays demonstrated that psychosine, the neurotoxic sphingolipid accumulated in Krabbe disease, accelerated the fibrillization of α-synuclein. This study demonstrates the occurrence of neuronal deposits of fibrillized proteins including α-synuclein, identifying Krabbe disease as a new α-synucleinopathy.

Inhibition of angiogenesis by ß-galactosylceramidase deficiency in globoid cell leukodystrophy.

Globoid cell leukodystrophy (Krabbe disease) is a neurological disorder of infants caused by genetic deficiency of the lysosomal enzyme ß-galactosylceramidase leading to accumulation of the neurotoxic metabolite 1-ß-d-galactosylsphingosine (psychosine) in the central nervous system. Angiogenesis plays a pivotal role in the physiology and pathology of the brain. Here, we demonstrate that psychosine has anti-angiogenic properties by causing the disassembling of endothelial cell actin structures at micromolar concentrations as found in the brain of patients with globoid cell leukodystrophy. Accordingly, significant alterations of microvascular endothelium were observed in the post-natal brain of twitcher mice, an authentic model of globoid cell leukodystrophy. Also, twitcher endothelium showed a progressively reduced capacity to respond to pro-angiogenic factors, defect that was corrected after transduction with a lentiviral vector harbouring the murine ß-galactosylceramidase complementary DNA. Finally, RNA interference-mediated ß-galactosylceramidase gene silencing causes psychosine accumulation in human endothelial cells and hampers their mitogenic and motogenic response to vascular endothelial growth factor. Accordingly, significant alterations were observed in human microvasculature from brain biopsy of a globoid cell leukodystrophy case. Together these data demonstrate that ß-galactosylceramidase deficiency induces significant alterations in endothelial neovascular responses that may contribute to central nervous system and systemic damages that occur in globoid cell leukodystrophy.