Astroglioma conditioned medium increases synaptic elimination and correlates with major histocompatibility complex of class I (MHC I) upregulation in PC12Cells

Neuroprotection by upregulation of the major histocompatibility complex class I (MHC I) in SOD1G93A mice

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease that progressively affects motoneurons, causing muscle atrophy and evolving to death. Astrocytes inhibit the expression of MHC-I by neurons, contributing to a degenerative outcome. The present study verified the influence of interferon β (IFN β) treatment, a proinflammatory cytokine that upregulates MHC-I expression, in SOD1G93A transgenic mice. For that, 17 days old presymptomatic female mice were subjected to subcutaneous application of IFN β (250, 1,000, and 10,000 IU) every other day for 20 days. Rotarod motor test, clinical score, and body weight assessment were conducted every third day throughout the treatment period. No significant intergroup variations were observed in such parameters during the pre-symptomatic phase. All mice were then euthanized, and the spinal cords collected for comparative analysis of motoneuron survival, reactive gliosis, synapse coverage, microglia morphology classification, cytokine analysis by flow cytometry, and RT-qPCR quantification of gene transcripts. Additionally, mice underwent Rotarod motor assessment, weight monitoring, and neurological scoring. The results show that IFN β treatment led to an increase in the expression of MHC-I, which, even at the lowest dose (250 IU), resulted in a significant increase in neuronal survival in the ALS presymptomatic period which lasted until the onset of the disease. The treatment also influenced synaptic preservation by decreasing excitatory inputs and upregulating the expression of AMPA receptors by astrocytes. Microglial reactivity quantified by the integrated density of pixels did not decrease with treatment but showed a less activated morphology, coupled with polarization to an M1 profile. Disease progression upregulated gene transcripts for pro- and anti-inflammatory cytokines, and IFN β treatment significantly decreased mRNA expression for IL4. Overall, the present results demonstrate that a low dosage of IFN β shows therapeutic potential by increasing MHC-I expression, resulting in neuroprotection and immunomodulation.

SESN2 Could Be a Potential Marker for Diagnosis and Prognosis in Glioma

(1) Background: Glioma is among the most common brain tumors, and is difficult to eradicate with current therapeutic strategies due to its highly invasive and aggressive characteristics. Sestrin2 (SESN2) is an autophagy inducer. The effect of SESN2 on glioma is controversial and unclear. (2) Methods: We downloaded related RNA-seq data from the TCGA and GTEx databases. Bioinformatic analyses including differential gene expression analysis, KM survival curve analysis, univariate and multivariate Cox regression analyses, nomogram analysis, ROC curve analysis, gene function enrichment analysis, and immune cell infiltration analysis were conducted. In addition, data from the Human Protein Atlas (HPA) database were collected to validate SESN2 expression in glioma. (3) Results: In comparison with normal tissue, expression of SESN2 in glioma tissue was higher, and those with higher expressions had significantly lower overall survival rates. The results of univariate Cox regression analyses showed that SESN2 can be a disadvantageous factor in poor glioma prognosis. Both nomograms and ROC curves confirmed these findings. Meanwhile, according to gene function analysis, SESN2 may be involved in immune responses and the tumor microenvironment (TME). Based on the HPA database results, SESN2 is localized in the cytosol and shows high expression in glioma. (4) Conclusions: The expression of SESN2 in gliomas was positively relevant to a poorer prognosis, suggesting that SESN2 could be used as a prognostic gene.

Stress increases MHC-I expression in dopaminergic neurons and induces autoimmune activation in Parkinson's disease

The expression of major histocompatibility complex class I (MHC-I), a key antigen-presenting protein, can be induced in dopaminergic neurons in the substantia nigra, thus indicating its possible involvement in the occurrence and development of Parkinson's disease. However, it remains unclear whether oxidative stress induces Parkinson's disease through the MHC-I pathway. In the present study, polymerase chain reaction and western blot assays were used to determine the expression of MHC-I in 1-methyl-4-phenylpyridinium (MPP⁺)-treated SH-SY5Y cells and a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced Parkinson's disease mouse model. The findings revealed that MHC-I was expressed in both models. To detect whether the expression of MHC-I was able to trigger the infiltration of cytotoxic T cells, immunofluorescence staining was used to detect cytotoxic cluster of differentiation 8 (CD8)⁺ T cell infiltration in the substantia nigra of MPTP-treated mice. The results indicated that the presentation of MHC-I in dopaminergic neurons was indeed accompanied by an increase in the number of CD8⁺ T cells. Moreover, in MPTP-induced Parkinson's disease model mice, the genetic knockdown of endogenous MHC-I, which was caused by injecting specific adenovirus into the substantia nigra, led to a significant reduction in CD8⁺ T cell infiltration and alleviated dopaminergic neuronal death. To further investigate the molecular mechanisms of oxidative stress-induced MHC-I presentation, the expression of PTEN-induced kinase 1 (PINK1) was silenced in MPP⁺-treated SH-SY5Y cells using specific small interfering RNA (siRNA), and there was more presentation of MHC-I in these cells compared with control siRNA-treated cells. Taken together, MPP⁺-/MPTP-induced oxidative stress can trigger MHC-I presentation and autoimmune activation, thus rendering dopaminergic neurons susceptible to immune cells and degeneration. This may be one of the mechanisms of oxidative stress-induced Parkinson's disease, and implies the potential neuroprotective role of PINK1 in oxidative stress-induced MHC-I presentation. All animal experiments were approved by the Southern Medical University Ethics Committee (No. 81802040, approved on February 25, 2018).

Molecular Effects of FDA-Approved Multiple Sclerosis Drugs on Glial Cells and Neurons of the Central Nervous System

Multiple sclerosis (MS) is characterized by peripheral and central inflammatory features, as well as demyelination and neurodegeneration. The available Food and Drug Administration (FDA)-approved drugs for MS have been designed to suppress the peripheral immune system. In addition, however, the effects of these drugs may be partially attributed to their influence on glial cells and neurons of the central nervous system (CNS). We here describe the molecular effects of the traditional and more recent FDA-approved MS drugs Fingolimod, Dimethyl Fumarate, Glatiramer Acetate, Interferon-β, Teriflunomide, Laquinimod, Natalizumab, Alemtuzumab and Ocrelizumab on microglia, astrocytes, neurons and oligodendrocytes. Furthermore, we point to a possible common molecular effect of these drugs, namely a key role for NFκB signaling, causing a switch from pro-inflammatory microglia and astrocytes to anti-inflammatory phenotypes of these CNS cell types that recently emerged as central players in MS pathogenesis. This notion argues for the need to further explore the molecular mechanisms underlying MS drug action.

Retrograde interferon-gamma signaling induces major histocompatibility class I expression in human-induced pluripotent stem cell-derived neurons

Objective

Injury-associated axon-intrinsic signals are thought to underlie pathogenesis and progression in many neuroinflammatory and neurodegenerative diseases, including multiple sclerosis (MS). Retrograde interferon gamma (IFN γ) signals are known to induce expression of major histocompatibility class I (MHC I) genes in murine axons, thereby increasing the susceptibility of these axons to attack by antigen-specific CD8⁺ T cells. We sought to determine whether the same is true in human neurons.

Methods

A novel microisolation chamber design was used to physically isolate and manipulate axons from human skin fibroblast-derived induced pluripotent stem cell (iPSC)-derived neuron-enriched neural aggregates. Fluorescent retrobeads were used to assess the fraction of neurons with projections to the distal chamber. Axons were treated with IFN γ for 72 h and expression of MHC class I and antigen presentation genes were evaluated by RT-PCR and immunofluorescence.

Results

Human iPSC-derived neural stem cells maintained as 3D aggregate cultures in the cell body chamber of polymer microisolation chambers extended dense axonal projections into the fluidically isolated distal chamber. Treatment of these axons with IFN γ resulted in upregulation of MHC class I and antigen processing genes in the neuron cell bodies. IFN γ-induced MHC class I molecules were also anterogradely transported into the distal axon.

Interpretation

These results provide conclusive evidence that human axons are competent to express MHC class I molecules, suggesting that inflammatory factors enriched in demyelinated lesions may render axons vulnerable to attack by autoreactive CD8⁺ T cells in patients with MS. Future work will be aimed at identifying pathogenic anti-axonal T cells in these patients.