Background: Multiple sclerosis (MS) is one of the most common autoimmune disorders characterized by the infiltration of immune cells into the brain and demyelination. The unwanted immunosuppressive side effect of therapeutically successful natalizumab led us to focus on the choroid plexus (CP), a key site for the first wave of immune cell infiltration in experimental autoimmune encephalomyelitis (EAE), for the control of immune cells trafficking. Adenosine A_2A receptor (A_2AR) is emerging as a potential pharmacological target to control EAE pathogenesis. However, the cellular basis for the A_2AR-mediated protection remains undetermined. Methods: In the EAE model, we assessed A_2AR expression and leukocyte trafficking determinants in the CP by immunohistochemistry and qPCR analyses. We determined the effect of the A_2AR antagonist KW6002 treatment at days 8–12 or 8–14 post-immunization on T cell infiltration across the CP and EAE pathology. We determined the critical role of the CP-A_2AR on T cell infiltration and EAE pathology by focal knock-down of CP-A_2AR via intracerebroventricular injection of CRE-TAT recombinase into the A_2AR^flox/flox mice. In the cultured CP epithelium, we also evaluated the effect of overexpression of A_2ARs or the A_2AR agonist CGS21680 treatment on the CP permeability and lymphocytes migration. Results: We found the specific upregulation of A_2AR in the CP associated with enhanced CP gateway activity peaked at day 12 post-immunization in EAE mice. Furthermore, the KW6002 treatment at days 8–12 or 8–14 post-immunization reduced T cell trafficking across the CP and attenuated EAE pathology. Importantly, focal CP-A_2AR knock-down attenuated the pathogenic infiltration of Th17⁺ cells across the CP via inhibiting the CCR6–CCL20 axis through NFκB/STAT3 pathway and protected against EAE pathology. Lastly, activation of A_2AR in the cultured epithelium by A_2AR overexpression or CGS21680 treatment increased the permeability of the CP epithelium and facilitated lymphocytes migration. Conclusion: These findings define the CP niche as one of the primary sites of A_2AR action, whereby A_2AR antagonists confer protection against EAE pathology. Thus, pharmacological targeting of the CP-A_2AR represents a novel therapeutic strategy for MS by controlling immune cell trafficking across CP.

Post-stroke depression (POSD) is a common difficulty and most predominant emotional syndrome after stroke often consequences in poor outcomes. In the present investigation, we have designed and studied the neurologically active celastrol/minocycline encapsulated with macrophages-derived exosomes functionalized PLGA nanoformulations (CMC-EXPL) to achieve enhanced anti-inflammatory behaviour and anti-depressant like activity in a Rat model of POSD. The animal model of POSD was established through stimulating process with chronic unpredictable mild stress (CUM) stimulations after procedure of middle cerebral artery occlusion (MCAO). Neuronal functions and Anti-inflammation behaviours were observed by histopathological (H&E) examination and Elisa analyses, respectively. The anti-depressive activity of the nanoformulations treated Rat models were evaluated by open-field and sucrose preference test methods. Microglial polarization was evaluated via flow-cytometry and qRT-PCR observations. The observed results exhibited that prepared nanoformulations reduced the POSD-stimulated depressive-like activities in rat models as well alleviated the neuronal damages and inflammatory responses in the cerebral hippocampus. Importantly, prepared CMC-EXPL nanoformulation effectively prevented the M1 pro-inflammatory polarization and indorsed M2 anti-inflammatory polarization, which indicates iNOS and CD86 levels significantly decreased and upsurged Arg-1 and CD206 levels. CMC-EXPL nanoformulation suggestively augmented anti-depressive activities and functional capability and also alleviated brain inflammation in POSD rats, demonstrating its therapeutic potential for POSD therapy.

Parkinson’s disease (PD), as a refractory neurological disorder with complex etiology, currently lacks effective therapeutic agents. Natural products (NPs), derived from plants, animals, or microbes, have shown promising effects in PD models through their antioxidative and anti-inflammatory properties, as well as the enhancement of mitochondrial homeostasis and autophagy. The misfolding and deposition of α-Synuclein (α-Syn), due to abnormal overproduction and impaired clearance, being central to the death of dopamine (DA) neurons. Thus, inhibiting α-Syn misfolding and aggregation has become a critical focus in PD discovery. This review highlights NPs that can reduce α-Syn aggregation by preventing its overproduction and misfolding, emphasizing their potential as novel drugs or adjunctive therapies for PD treatment, thereby providing further insights for clinical translation.

Adenosine A2A receptor (A2AR) antagonists have been consistently demonstrated to protect against multiple sclerosis (MS) pathology, but A2AR knockout (A2AR−/−) mice exhibit exacerbated immune injury, raising concerns regarding the use of A2AR antagonists for MS treatment. Here, we revealed the critical involvement of A2AR-mediated interactions between Th1+ T cells and the choroid plexus (ChP) epithelium in the pathology of experimental autoimmune encephalomyelitis (EAE). We assessed the effects of A2AR knockout on ChP gateway activity and the interferon gamma (IFN-γ)-secreting capacity of Th1+ T cells in an EAE model by immunofluorescence, qPCR and flow cytometry (FCM). We also investigated the effects of A2AR-mediated interactions between Th1+ T cells and the ChP epithelium on ChP gateway activity in vivo via intracerebroventricular (ICV) injection of Th1+ T cells and in vitro via coculture of ChP epithelial cells and splenic Th1+ T cells. We further knocked down IFN-γ receptor 1 (IFNGR1) specifically in the ChP of A2AR−/− mice via ICV injection of AAV2/5-shRNA (IFNGR1) to disrupt the interactions between Th1+ T cells and the ChP epithelium and thus assess the roles of these interactions in the development of EAE pathology. A2AR knockout disrupted the ChP barrier and increased T-cell infiltration across the ChP in EAE model mice. Coculture of splenic Th1+ T cells and ChP epithelial cells revealed that A2AR knockout in ChP epithelial cells strengthened the ChP barrier and attenuated T-cell migration, whereas A2AR knockout in Th1+ T cells increased the accumulation of Th1+ T cells in the ChP via the secretion of IFN-γ. Consistent with the coculture results, ICV injection of activated splenic Th1+ T cells from A2AR−/− mice increased the accumulation of T cells in the ChP to a greater extent than did injection of Th1+ T cells from A2AR+/+ mice. This effect was due to the increased secretion of IFN-γ in A2AR−/− mice compared with A2AR+/+ mice. Finally, ChP-specific knockdown of IFNGR1 attenuated A2AR knockout-induced T-cell infiltration, brain inflammation and EAE pathology. A2AR-mediated interactions between Th1+ T cells and the ChP epithelium via the secretion of IFN-γ from CD4+ T cells and the binding IFN-γ to IFNGR1 in the ChP epithelium control immune cell invasion and the development of EAE pathology in A2AR−/− mice.

Disease-modifying therapies (DMTs) that prevent immune cell infiltration into the brain have demonstrated efficacy in multiple sclerosis (MS) treatment. However, their unpredictable adverse effects necessitate the development of safer therapeutic alternatives. The choroid plexus (ChP) functions as a crucial barrier against immune cell invasion, and previous studies have shown that preventing immune cell infiltration across the ChP reduces brain lesion in MS animal models. Understanding ChP barrier regulation is therefore essential for identifying novel therapeutic targets for MS. Here, we explored the role of Ste20-related proline/alanine-rich kinase (SPAK) in experimental autoimmune encephalomyelitis (EAE). We examined the expression patterns of SPAK signaling in ChP using immunofluorescence in the EAE model. To investigate the roles of SPAK, matrix metalloproteinase (MMP) 2 and MMP9 in EAE pathology, we performed ChP-specific gene manipulation via intracerebroventricular (ICV) injection of recombinant adeno-associated virus 2/5 (rAAV2/5). T cell infiltration into the central nervous system (CNS) was analyzed using CD4 immunostaining and flow cytometry. We employed cell immunofluorescence, transwell assays, and rescue experiments in vitro to study SPAK’s effects on ChP epithelial barrier integrity. We also evaluated the protective effects of SPAK-Na-K-2Cl cotransporter-1 (NKCC1) inhibitors (ZT-1a and bumetanide) on immune invasion and demyelination during EAE using pharmacological approaches. Following EAE induction, we observed progressive increases in both total and phosphorylated SPAK levels in ChP epithelium. Notably, ChP-specific SPAK knockdown significantly reduced T cell invasion and ameliorated EAE pathology, while SPAK overexpression exacerbated these effects. Bulk RNA sequencing and subsequent qPCR validation revealed that SPAK knockdown decreased the expression of MMP2 and MMP9, MMPs that compromise barrier integrity by degrading tight junction proteins. In vitro studies demonstrated that SPAK overexpression impaired ChP barrier function through the activator protein-1 (AP-1)-MMP2/9-zonula occludens-1 (ZO-1) axis. Furthermore, ChP-specific knockdown of either MMP2 or MMP9 protected against EAE pathology. Additionally, we identified SPAK-NKCC1 antagonists (bumetanide and ZT-1a) as promising therapeutic candidates for MS/EAE treatment. Our findings demonstrate that targeting ChP-SPAK signaling represents a novel therapeutic strategy for MS treatment.