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Background and Hypothesis: Organ transplantation reverses cognitive impairment in chronic kidney disease (CKD), indicating that cognitive impairment driven by CKD is therapeutically amendable. We recently demonstrated that impaired cognition in CKD is linked to IL-1β-release from microglia and IL-1R1-signaling in neuronal cells, thereby identifying a signaling pathway that can be exploited therapeutically. However, the mechanism of IL-1β-maturation in microglia in CKD remains unknown. We hypothesized that microglia cells require caspase-1 for CKD-driven cognitive impairment., Methods: We used a combination of single cell analyses, in situ analyses, genetically modified mouse models (including newly generated Cre-LoxP mouse models) and in vitro models. The current study builds on a recently identified intercellular crosstalk between microglia and neurons that impairs cognition in chronic kidney disease (CKD)., Results: Here, we show that despite NLRP3 inflammasome activation in the brain and protection of mice with constitutive NLRP3 deficiency from CKD-induced cognitive impairment, (i) caspase-1 is not required for IL-1β maturation in microglia and (ii) targeted caspase-1 deficiency in microglia does not improve cognition in CKD mice. These data indicate that IL-1β maturation in microglia is independent of the NLRP3-caspase-1 interaction in CKD. Indeed, microglia activation in CKD induces noncanonical, cathepsin C-caspase-8 mediated IL-1β maturation. Depletion of cathepsin C or caspase-8 blocks IL-1β maturation in microglia. Preliminary analyses suggest that noncanonical microglia IL-1β maturation occurs also in diabetes mellitus., Conclusion: These results identify a noncanonical IL-1β-maturation pathway as a potential therapeutic target to combat microglia-induced neuronal dysfunction in CKD and possible other peripheral diseases., (© The Author(s) 2024. Published by Oxford University Press on behalf of the ERA.)

Context: Obese women suffer from anovulation and infertility, which are driven by oxidative stress caused by increased levels of lipid peroxides and circulating oxidized low-density lipoprotein (oxLDL). OxLDL binds to lectin-like oxLDL receptor 1 (LOX-1), cluster of differentiation 36 (CD36), and toll-like receptor 4 (TLR4) and causes cell death in human granulosa cells (GCs)., Objective: Our objective was to reveal whether treatment with antioxidants resveratrol (RES) and/or desferoxamine (DFO) protect GCs from oxLDL-induced damage., Design and Setting: This basic research study was performed at the Institute of Anatomy and the Clinic of Reproductive Medicine., Patients: Patients were women undergoing in vitro fertilization therapy., Main Outcome Measures: GC cultures were treated with oxLDL alone or with RES or DFO under serum-free conditions for up to 36 hours. Dead cells were determined by propidium iodide uptake, cleaved caspase-3 expression, and electron microscopy. Mitosis was detected by Ki-67 immunostaining. LOX-1, TLR4, CD36, and heat-shock protein 60 were examined by Western blot. Measurement of oxidative stress markers (8-iso-prostaglandin F2α, advanced glycation end products, and protein carbonyl content) was conducted with ELISA kits., Results: Different subtypes of human GCs exposed to RES or DFO were protected as evidenced by the lack of cell death, enhanced mitosis, induction of protective autophagy, reduction of oxidative stress markers, and reduced expression of LOX-1, TLR4, CD36, and heat-shock protein 60. Importantly, RES could restore steroid biosynthesis in cytokeratin-positive GCs, which exhibited significant induction of steroidogenic acute regulatory protein., Conclusions: RES and DFO exert a protective effect on human GCs. Thus, RES and DFO may help improve the treatment of obese women or polycystic ovarian syndrome patients undergoing in vitro fertilization therapy.

Background: Glioblastoma multiforme is the most common lethal brain tumor in human adults, with no major therapeutic breakthroughs in recent decades. Research is based mostly on human tumor cell lines deprived of their organotypic environment or inserted into immune-deficient animals required for graft survival. Here, we describe how glioblastoma specimens obtained from surgical biopsy material can be sectioned and transferred into cultures within minutes., Methods: Slices were kept in 6-well plates, allowing direct observation, application of temozolomide, and irradiation. At the end of experiments, slice cultures were processed for histological analysis including hematoxylin-eosin staining, detection of proliferation (Ki67), apoptosis/cell death (cleaved caspase 3, propidium iodide), DNA double-strand breaks (γH2AX), and neural subpopulations. First clinical trials employed irradiation with the heavy ion carbon for the treatment of glioblastoma patients, but the biological effects and most effective dose regimens remain to be established. Therefore, we developed an approach to expose glioblastoma slice cultures to (12)C and X-rays., Results: We found preservation of the individual histopathology over at least 16 days. Treatments resulted in activation of caspase 3, inhibition of proliferation, and cell loss. Irradiation induced γH2AX. In line with clinical observations, individual tumors differed significantly in their susceptibility to temozolomide (0.4%-2.5% apoptosis and 1%-15% cell loss)., Conclusion: Glioblastoma multiforme slice cultures provide a unique tool to explore susceptibility of individual tumors for specific therapies including heavy ions, thus potentially allowing more personalized treatments plus exploration of mechanisms of (and strategies to overcome) tumor resistance.

The lack of classical lymph vessels within brain tissue complicates immune surveillance of the CNS, and therefore, cellular emigration out of the CNS parenchyma requires alternate pathways. Whereas invasion of blood-derived mononuclear cells and their transformation into ramified, microglia-like cells in areas of axonal degeneration across an intact BBB have been demonstrated, it still remained unclear whether these cells reside permanently, undergo apoptosis, or leave the brain to present antigen in lymphoid organs. With the use of ECL of mice and injection of GFP-expressing monocytes, we followed the appearance of injected cells in spleen and LNs and the migratory pathways in whole-head histological sections. Monocytes migrated from the lesion site to deep CLNs, peaking in number at Day 7, but they were virtually absent in spleen and in superficial CLNs and inguinal LNs until Day 21 after lesion/injection. In whole-head sections, GFP monocytes were found attached to the olfactory nerves and located within the nasal mucosa at 48 hpi. Thus, monocytes are capable of migrating from lesioned brain areas to deep CLNs and use the cribriform plate as an exit route.

Immune cells enter the central nervous system (CNS) from the circulation under normal conditions for immunosurveillance and in inflammatory neurologic diseases. This review describes the distinct anatomic features of the CNS vasculature that permit it to maintain parenchymal homeostasis and which necessitate specific mechanisms for neuroinflammation to occur. We review the historical evolution of the concept of the blood-brain barrier and discuss distinctions between diffusion/transport of solutes and migration of cells from the blood to CNS parenchyma. The former is regulated at the level of capillaries, whereas the latter takes place in postcapillary venules. We summarize evidence that entry of immune cells into the CNS parenchyma in inflammatory conditions involves 2 differently regulated steps: transmigration of the vascular wall into the perivascular space and progression across the glia limitans into the parenchyma.

The Virchow-Robin spaces (VRS), perivascular compartments surrounding small blood vessels as they penetrate the brain parenchyma, are increasingly recognized for their role in leucocyte trafficking as well as for their potential to modulate immune responses. In the present study, we investigated VRS numbers and volumes in different brain regions in 45 multiple sclerosis patients and 30 healthy controls of similar age and gender distribution, applying three different MRI sequence modalities (T(2)-weighted, T(1)-weighted and FLAIR). VRS were detected in comparable numbers in both multiple sclerosis patients and healthy individuals, indicating that perivascular compartments present on MRI are not a unique feature of multiple sclerosis. However, multiple sclerosis patients had significantly larger VRS volumes than healthy controls (P = 0.004). This finding was not explained by a significantly lower brain parenchymal fraction (BPF), resulting from a higher degree of atrophy, in the patient cohort. In a multiple linear regression analysis, age had a significant influence on VRS volumes in the control group but not in multiple sclerosis patients (P = 0.023 and P = 0.263, respectively). A subsequent prospective longitudinal substudy with monthly follow-up MRI over a period of up to 12 months in 18 patients revealed a significant increase in VRS volumes and counts accompanying the occurrence of contrast-enhancing lesions (CEL). At time points when blood-brain barrier (BBB) breakdown was indicated by the appearance of CEL, total VRS volumes and counts were significantly higher compared with preceding time points without CEL (P = 0.011 and P = 0.041, respectively), whereas a decrease thereafter was not statistically significant. Thus, our data points to an association of VRS with CEL as a sign for inflammation rather than with factors such as age, observed in healthy controls, and therefore suggests a role of VRS in inflammatory processes of the brain.

It has long been recognized that insults to the cerebral cortex, such as trauma, ischaemia or infections, may result in the development of epilepsy, one of the most common neurological disorders. Human and animal studies have suggested that perturbations in neurovascular integrity and breakdown of the blood-brain barrier (BBB) lead to neuronal hypersynchronization and epileptiform activity, but the mechanisms underlying these processes are not known. In this study, we reveal a novel mechanism for epileptogenesis in the injured brain. We used focal neocortical, long-lasting BBB disruption or direct exposure to serum albumin in rats (51 and 13 animals, respectively, and 26 controls) as well as albumin exposure in brain slices in vitro. Most treated slices (72%, n = 189) displayed hypersynchronous propagating epileptiform field potentials when examined 5-49 days after treatment, but only 14% (n = 71) of control slices showed similar responses. We demonstrate that direct brain exposure to serum albumin is associated with albumin uptake into astrocytes, which is mediated by transforming growth factor beta receptors (TGF-betaRs). This uptake is followed by down regulation of inward-rectifying potassium (Kir 4.1) channels in astrocytes, resulting in reduced buffering of extracellular potassium. This, in turn, leads to activity-dependent increased accumulation of extracellular potassium, resulting in facilitated N-methyl-d-aspartate-receptor-mediated neuronal hyperexcitability and eventually epileptiform activity. Blocking TGF-betaR in vivo reduces the likelihood of epileptogenesis in albumin-exposed brains to 29.3% (n = 41 slices, P < 0.05). We propose that the above-described cascade of events following common brain insults leads to brain dysfunction and eventually epilepsy and suggest TGF-betaRs as a possible therapeutic target.

Although drainage pathways of soluble antigens from brain to cervical lymph nodes have been well established, there is no direct evidence for similar routes of leukocytes leaving the central nervous system. We developed a protocol allowing the cross-sectioning of an entire head-neck preparation while preserving the signal of the GFP. We monitored how GFP-expressing CD4 T lymphocytes injected into the entorhinal cortex after lesion or the lateral ventricle of unlesioned C57/bl6 mice reach cervical lymph nodes. Irrespective of the injection site, we demonstrate their passage through the cribroid plate, appearance in the nasal mucosa, and specific accumulation in one of the cervical lymph nodes.

Energy dissipating mechanisms and their regulatory components represent key elements of metabolism and may offer novel targets in the treatment of metabolic disorders, such as obesity and diabetes. Recent studies have shown that a mitochondrial uncoupling protein (UCP2), which uncouples mitochondrial oxidation from phosphorylation, is expressed in the rodent brain by neurons that are known to regulate autonomic, metabolic, and endocrine processes. To help establish the relevance of these rodent data to primate physiology, we now examined UCP2 messenger RNA and peptide expressions in the brain and pituitary gland of nonhuman primates. In situ hybridization histochemistry showed that UCP2 messenger RNA is expressed in the paraventricular, supraoptic, suprachiasmatic, and arcuate nuclei of the primate hypothalamus and also in the anterior lobe of the pituitary gland. Immunocytochemistry revealed abundant UCP2 expression in cell bodies and axonal processes in the aforementioned nuclei as well as in other hypothalamic and brain stem regions and all parts of the pituitary gland. In the hypothalamus, UCP2 was coexpressed with neuropeptide Y, CRH, oxytocin, and vasopressin. In the pituitary, vasopressin and oxytocin-producing axonal processes in the posterior lobe and POMC cells in the intermediate and anterior lobes expressed UCP2. On the other hand, none of the GH-producing cells of the anterior pituitary was found to produce UCP2. The abundance and distribution pattern of UCP2 in the primate brain and pituitary suggest that this protein is evolutionary conserved and may relate to central autonomic, endocrine and metabolic regulation.