The choroid plexus (CP), located in each of the four ventricles of the brain, is formed by a monolayer of epithelial cells that surrounds a highly vascularized connective tissue with permeable capillaries. These cells are joined by tight junctions forming the blood–cerebrospinal fluid barrier (BCSFB), which strictly regulates the exchange of substances between the blood and cerebrospinal fluid (CSF). The primary purpose of the CP is to secrete CSF, but it also plays a role in the immune surveillance of the central nervous system (CNS) and in the removal of neurotoxic compounds from the CSF. According to recent findings, the CP is also involved in the modulation of the circadian cycle and neurogenesis. In diseases such as Alzheimer’s disease (AD), the function of the CP is impaired, resulting in an altered secretory, barrier, transport, and immune function. This review describes the current state of knowledge concerning the roles of the CP and BCSFB in the pathophysiology of AD and summarizes recently proposed therapies that aim to restore CP and BCSFB functions.

Nocardiosis is a rare opportunistic infection with increasing incidence. Given its rarity, data on the prognosis and distribution are scarce and essential. Retrospective study reviewing all nocardiosis cases diagnosed at our tertiary care hospital from January 2019 to January 2023. A positive Nocardia spp. culture was identified in 20 patients. Nocardia isolation was considered colonization in 2 patients, but the other 18 cases were considered as disease, 6 (33.3%) of which were classified as disseminated nocardiosis (DN). The mean age was 64.0±14.05 years-old and 75% were males. One or more immunosuppressive conditions were identified in 70% of patients, including diabetes mellitus (n=9), active solid tumors (n=3), autoimmune diseases (n=3) and HIV infection with CD4+ < 200 cel/uL (n=2). Among the immunocompromised patients, 28,6% were being treated with high-dose corticosteroid therapy. The lung was the most common site of infection (85%) and most cultures were initially retrieved for lower respiratory tract samples (85%) evaluated for mycobacteria in modified Middlebrook 7H9 Broth. Lymphopenia was observed in 38.9% of patients.The most frequently isolated species were N.nova/africana (n=7), N.cyriacigeorgica (n=4) and N.pseudobrasiliensis (n=3). N.cyriacigeorgica was identified in the two cases considered colonization. Most patients (94.4%) were treated with antimicrobials, 50.0% in monotherapy and 44.4% in combination therapy. The most frequently prescribed antibiotics were co-trimoxazole (94.4%), imipenem (22.2%) and linezolid (16.7%). Selected antimicrobial agents were generally effective, with linezolid and co-trimoxazole having the highest susceptibility rates (100% susceptibility). The median [IQR] duration of treatment was 238 [45–720] and 170 [5–360] days for localized and DN, respectively. The overall one- year case fatality was 25% and was higher in patients with DN (80%). Nocardiosis is an uncommon but emerging disease which can occur both in immunocompetent and immunocompromised patients. The present study reports a case series on Nocardiosis from Portugal and provides important information of this disease. As the outcomes are poor, early recognition and prompt treatment are essential to improve the outcome. All Authors: No reported disclosures