Increased HLA-DR expression and cortical demyelination in MS links with HLA-DR15

A protective effect of lower MHC-II expression in MOGAD

Myelin oligodendrocyte glycoprotein-antibody-associated disease (MOGAD) is a demyelinating central nervous system disorder. We aimed to uncover immune pathways altered in MOGAD to predict disease progression. Using nanostring nCounter technology, we analyzed immune gene expression in PBMCs from MOGAD patients and compare it with healthy controls (HCs). We found 35 genes that distinguished MOGAD patients and HCs. We then validated those results in a larger cohort including MS and NMOSD patients. Expressions of HLA-DRA was significantly lower in MOGAD patients. This reduction in HLA-DRA, correlated with a monophasic disease course and greater brain volume, enhancing our ability to predict MOGAD progression.

Determination of HLA class II risk alleles and prediction of self/non-self-epitopes contributing Hashimoto's thyroiditis in a group of Iranian patients

One of the probable hypotheses for the onset of autoimmunity is molecular mimicry. This study aimed to determine the HLA-II risk alleles for developing Hashimoto's thyroiditis (HT) in order to analyze the molecular homology between candidate pathogen-derived epitopes and potentially self-antigens (thyroid peroxidase, TPO) based on the presence of HLA risk alleles. HLA-DRB1/-DQB1 genotyping was performed in 100 HT patients and 330 ethnically matched healthy controls to determine the predisposing/protective alleles for HT disease. Then, in silico analysis was conducted to examine the sequence homology between epitopes derived from autoantigens and four potentially relevant pathogens and their binding capacities to HLA risk alleles based on peptide docking analysis. We identified HLA-DRB1*03:01, *04:02, *04:05, and *11:04 as predisposing alleles and DRB1*13:01 as a potentially predictive allele for HT disease. Also, DRB1*11:04 ~ DQB1*03:01 (Pc = 0.002; OR, 3.97) and DRB1*03:01 ~ DQB1*02:01 (Pc = 0.004; OR, 2.24) haplotypes conferred a predisposing role for HT. Based on logistic regression analysis, carrying risk alleles increased the risk of HT development 4.5 times in our population (P = 7.09E-10). Also, ROC curve analysis revealed a high predictive power of those risk alleles for discrimination of the susceptible from healthy individuals (AUC, 0.70; P = 6.6E-10). Analysis of peptide sequence homology between epitopes of TPO and epitopes derived from four candidate microorganisms revealed a homology between envelop glycoprotein D of herpes virus and sequence 151-199 of TPO with remarkable binding capacity to HLA-DRB1*03:01 allele. Our findings indicate the increased risk of developing HT in those individuals carrying HLA risk alleles which can also be related to herpes virus infection.

Causal role of immune cells in obstructive sleep apnea hypopnea syndrome: Mendelian randomization study

BACKGROUND

Despite being one of the most prevalent sleep disorders, obstructive sleep apnea hypoventilation syndrome (OSAHS) has limited information on its immunologic foundation. The immunological underpinnings of certain major psychiatric diseases have been uncovered in recent years thanks to the extensive use of genome-wide association studies (GWAS) and genotyping techniques using high-density genetic markers (e.g., SNP or CNVs). But this tactic hasn't yet been applied to OSAHS. Using a Mendelian randomization analysis, we analyzed the causal link between immune cells and the illness in order to comprehend the immunological bases of OSAHS.

AIM

To investigate the immune cells' association with OSAHS via genetic methods, guiding future clinical research.

METHODS

A comprehensive two-sample mendelian randomization study was conducted to investigate the causal relationship between immune cell characteristics and OSAHS. Summary statistics for each immune cell feature were obtained from the GWAS catalog. Information on 731 immune cell properties, such as morphologic parameters, median fluorescence intensity, absolute cellular, and relative cellular, was compiled using publicly available genetic databases. The results' robustness, heterogeneity, and horizontal pleiotropy were confirmed using extensive sensitivity examination.

RESULTS

Following false discovery rate (FDR) correction, no statistically significant effect of OSAHS on immunophenotypes was observed. However, two lymphocyte subsets were found to have a significant association with the risk of OSAHS: Basophil %CD33dim HLA DR- CD66b- (OR = 1.03, 95%CI = 1.01-1.03, P < 0.001); CD38 on IgD+ CD24- B cell (OR = 1.04, 95%CI = 1.02-1.04, P = 0.019).

CONCLUSION

This study shows a strong link between immune cells and OSAHS through a gene approach, thus offering direction for potential future medical research.

Autophagy in Multiple Sclerosis: Phagocytosis and Autophagy of Oligodendrocyte Precursor Cells

Multiple sclerosis (MS) is a leading cause of chronic neurological dysfunction in young to middle-aged adults, affecting approximately 2.5 million people worldwide. It is characterized by inflammation, multifocal demyelination, axonal loss, and white and gray matter gliosis. Autophagy is a highly conserved protein degradation pathway. Polymorphisms in autophagy-related genes have been implicated in a variety of autoimmune diseases, including systemic lupus erythematosus, rheumatoid arthritis, psoriasis and MS. However, the significance of autophagy in MS remains to be elucidated. This paper aims to explore the potential role of autophagy-related genes in MS diseases by using bioinformatics combined with machine learning methods. Finally, we obtained 9 autophagy genes with the highest correlation with MS, and further changes in these autophagy genes were verified in the experimental autoimmune encephalomyelitis (EAE) model and oligodendrocyte precursor cells (OPCs) engulfed myelin debris (MD). Combined with bioinformatic analysis and experimental data, Becn1 showed obvious expression abnormalities suggesting that this gene has vital functions in autophagy and MD engulfed by OPCs. This work will be of great significance for the further exploration of autophagy-related genes in demyelinating diseases.

High-resolution DNA methylation screening of the major histocompatibility complex in multiple sclerosis

Background

The HLA-DRB1 gene in the major histocompatibility complex (MHC) region in chromosome 6p21 is the strongest genetic factor identified as influencing multiple sclerosis (MS) susceptibility. DNA methylation changes associated with MS have been consistently detected at the MHC region. However, understanding the full scope of epigenetic regulations of the MHC remains incomplete, due in part to the limited coverage of this region by standard whole genome bisulfite sequencing or array-based methods.

Methods

We developed and validated an MHC capture protocol coupled with bisulfite sequencing and conducted a comprehensive analysis of the MHC methylation landscape in blood samples from 147 treatment naïve MS study participants and 129 healthy controls.

Results

We identified 132 differentially methylated region (DMRs) within MHC region associated with disease status. The DMRs overlapped with established MS risk loci. Integration of the MHC methylome with human leukocyte antigen (HLA) genetic data indicate that the methylation changes are significantly associated with HLA genotypes. Using DNA methylation quantitative trait loci (mQTL) mapping and the causal inference test (CIT), we identified 643 cis-mQTL-DMRs paired associations, including 71 DMRs possibly mediating causal relationships between 55 single nucleotide polymorphisms (SNPs) and MS risk.

Results

The results describe MS-associated methylation changes in MHC region and highlight the association between HLA genotypes and methylation changes. Results from the mQTL and CIT analyses provide evidence linking MHC region variations, methylation changes, and disease risk for MS.

Genetic variation in the human leukocyte antigen region confers susceptibility to Clostridioides difficile infection

Clostridioides difficile (C. diff.) infection (CDI) is a leading cause of hospital acquired diarrhea in North America and Europe and a major cause of morbidity and mortality. Known risk factors do not fully explain CDI susceptibility, and genetic susceptibility is suggested by the fact that some patients with colons that are colonized with C. diff. do not develop any infection while others develop severe or recurrent infections. To identify common genetic variants associated with CDI, we performed a genome-wide association analysis in 19,861 participants (1349 cases; 18,512 controls) from the Electronic Medical Records and Genomics (eMERGE) Network. Using logistic regression, we found strong evidence for genetic variation in the DRB locus of the MHC (HLA) II region that predisposes individuals to CDI (P > 1.0 × 10-14; OR 1.56). Altered transcriptional regulation in the HLA region may play a role in conferring susceptibility to this opportunistic enteric pathogen.

Integrated Analysis of Immune Infiltration and Hub Pyroptosis-Related Genes for Multiple Sclerosis

Purpose

Studies on overall immune infiltration and pyroptosis in patients with multiple sclerosis (MS) are limited. This study explored immune cell infiltration and pyroptosis in MS using bioinformatics and experimental validation.

Methods

The GSE131282 and GSE135511 microarray datasets including brain autopsy tissues from controls and MS patients were downloaded for bioinformatic analysis. The gene expression-based deconvolution method, CIBERSORT, was used to determine immune infiltration. Differentially expressed genes (DEGs) and functional enrichments were analyzed. We then extracted pyroptosis-related genes (PRGs) from the DEGs by using machine learning strategies. Their diagnostic ability for MS was evaluated in both the training set (GSE131282 dataset) and validation set (GSE135511 dataset). In addition, messenger RNA (mRNA) expression of PRGs was validated using quantitative real-time polymerase chain reaction (qRT-PCR) in cortical tissue from an experimental autoimmune encephalomyelitis (EAE) model of MS. Moreover, the functional enrichment pathways of each hub PRG were estimated. Finally, co-expressed competitive endogenous RNA (ceRNA) networks of PRGs in MS were constructed.

Results

Among the infiltrating cells, naive CD4+ T cells (P=0.006), resting NK cells (P=0.002), activated mast cells (P=0.022), and neutrophils (P=0.002) were significantly higher in patients with MS than in controls. The DEGs of MS were screened. Analysis of enrichment pathways showed that the pathways of transcriptional regulatory mechanisms and ion channels associating with pyroptosis. Four PRGs genes CASP4, PLCG1, CASP9 and NLRC4 were identified. They were validated in both the GSE135511 dataset and the EAE model by using qRT-PCR. CASP4 and NLRC4 were ultimately identified as stable hub PRGs for MS. Single-gene Gene Set Enrichment Analysis showed that they mainly participated in biosynthesis, metabolism, and organism resistance. ceRNA networks containing CASP4 and NLRC4 were constructed.

Conclusion

MS was associated with immune infiltration. CASP4 and NLRC4 were key biomarkers of pyroptosis in MS.

The genetic variant rs55986091 HLA-DQB1 is associated with a protective effect against cervical cancer

Introduction

Cervical cancer (CC) is a prevalent malignancy affecting women globally. The primary causative factor of CC is the high-risk oncogenic human papillomavirus (HR-HPV). However, it is noteworthy that not all women infected with HR-HPV develop cancer, indicating the potential involvement of genetic predisposition in the development of CC. This study aims to identify genetic risks and their distribution in groups of women with different epidemiological features of HR-HPV.

Materials and methods

A comparison was conducted among four groups of women, comprising 218 HPV-negative women, 120 HPV-positive women, 191 women diagnosed with cervical intraepithelial neoplasia (CIN) grade 2 or 3, and 124 women diagnosed with CC. The analysis focused on four single nucleotide polymorphisms (SNPs): rs55986091 in HLA-DQB1, rs138446575 in TTC34, rs1048943 in CYP1A1, and rs2910164 in miRNA-146a.

Results

The rs55986091-A allele exhibited a protective effect within the "CC" group when compared to the "HPV-Negative" group (OR = 0.4, 95% CI= 0.25-0.65) using a log-additive model. Additionally, similar protective effects were observed in the "CIN 2/3" group compared to the "HPV-Negative" group (OR = 0.47, 95% CI = 0.28-0.79).

Conclusion

The data obtained emphasize the importance of developing PCR-based diagnostic kits for the identification of SNP alleles, particularly for rs55986091, among HR-HPV-positive women within the Russian population.

A deep transcriptome meta-analysis reveals sex differences in multiple sclerosis

BACKGROUND

Multiple sclerosis (MS), a chronic auto-immune, inflammatory, and degenerative disease of the central nervous system, affects both males and females; however, females suffer from a higher risk of developing MS (2-3:1 ratio relative to males). The precise sex-based factors influencing risk of MS are currently unknown. Here, we explore the role of sex in MS to identify molecular mechanisms underlying observed MS sex differences that may guide novel therapeutic approaches tailored for males or females.

METHODS

We performed a rigorous and systematic review of genome-wide transcriptome studies of MS that included patient sex data in the Gene Expression Omnibus and ArrayExpress databases following PRISMA statement guidelines. For each selected study, we analyzed differential gene expression to explore the impact of the disease in females (IDF), in males (IDM) and our main goal: the sex differential impact of the disease (SDID). Then, for each scenario (IDF, IDM and SDID) we performed 2 meta-analyses in the main tissues involved in the disease (brain and blood). Finally, we performed a gene set analysis in brain tissue, in which a higher number of genes were dysregulated, to characterize sex differences in biological pathways.

RESULTS

After screening 122 publications, the systematic review provided a selection of 9 studies (5 in blood and 4 in brain tissue) with a total of 474 samples (189 females with MS and 109 control females; 82 males with MS and 94 control males). Blood and brain tissue meta-analyses identified, respectively, 1 (KIR2DL3) and 13 (ARL17B, CECR7, CEP78, IFFO2, LOC401127, NUDT18, RNF10, SLC17A5, STMP1, TRAF3IP2-AS1, UBXN2B, ZNF117, ZNF488) MS-associated genes that differed between males and females (SDID comparison). Functional analyses in the brain revealed different altered immune patterns in females and males (IDF and IDM comparisons). The pro-inflammatory environment and innate immune responses related to myeloid lineage appear to be more affected in females, while adaptive responses associated with the lymphocyte lineage in males. Additionally, females with MS displayed alterations in mitochondrial respiratory chain complexes, purine, and glutamate metabolism, while MS males displayed alterations in stress response to metal ion, amine, and amino acid transport.

CONCLUSION

We found transcriptomic and functional differences between MS males and MS females (especially in the immune system), which may support the development of new sex-based research of this disease. Our study highlights the importance of understanding the role of biological sex in MS to guide a more personalized medicine.

Epstein-Barr virus and multiple sclerosis

Epstein-Barr virus (EBV) is a ubiquitous human lymphotropic herpesvirus with a well-established causal role in several cancers. Recent studies have provided compelling epidemiological and mechanistic evidence for a causal role of EBV in multiple sclerosis (MS). MS is the most prevalent chronic inflammatory and neurodegenerative disease of the central nervous system and is thought to be triggered in genetically predisposed individuals by an infectious agent, with EBV as the lead candidate. How a ubiquitous virus that typically leads to benign latent infections can promote cancer and autoimmune disease in at-risk populations is not fully understood. Here we review the evidence that EBV is a causal agent for MS and how various risk factors may affect EBV infection and immune control. We focus on EBV contributing to MS through reprogramming of latently infected B lymphocytes and the chronic presentation of viral antigens as a potential source of autoreactivity through molecular mimicry. We consider how knowledge of EBV-associated cancers may be instructive for understanding the role of EBV in MS and discuss the potential for therapies that target EBV to treat MS.

A Systematic Review of Tissue and Single Cell Transcriptome/Proteome Studies of the Brain in Multiple Sclerosis

Multiple sclerosis (MS) is an inflammatory demyelinating and degenerative disease of the central nervous system (CNS). Although inflammatory responses are efficiently treated, therapies for progression are scarce and suboptimal, and biomarkers to predict the disease course are insufficient. Cure or preventive measures for MS require knowledge of core pathological events at the site of the tissue damage. Novelties in systems biology have emerged and paved the way for a more fine-grained understanding of key pathological pathways within the CNS, but they have also raised questions still without answers. Here, we systemically review the power of tissue and single-cell/nucleus CNS omics and discuss major gaps of integration into the clinical practice. Systemic search identified 49 transcriptome and 11 proteome studies of the CNS from 1997 till October 2021. Pioneering molecular discoveries indicate that MS affects the whole brain and all resident cell types. Despite inconsistency of results, studies imply increase in transcripts/proteins of semaphorins, heat shock proteins, myelin proteins, apolipoproteins and HLAs. Different lesions are characterized by distinct astrocytic and microglial polarization, altered oligodendrogenesis, and changes in specific neuronal subtypes. In all white matter lesion types, CXCL12, SCD, CD163 are highly expressed, and STAT6- and TGFβ-signaling are increased. In the grey matter lesions, TNF-signaling seems to drive cell death, and especially CUX2-expressing neurons may be susceptible to neurodegeneration. The vast heterogeneity at both cellular and lesional levels may underlie the clinical heterogeneity of MS, and it may be more complex than the current disease phenotyping in the clinical practice. Systems biology has not solved the mystery of MS, but it has discovered multiple molecules and networks potentially contributing to the pathogenesis. However, these results are mostly descriptive; focused functional studies of the molecular changes may open up for a better interpretation. Guidelines for acceptable quality or awareness of results from low quality data, and standardized computational and biological pipelines may help to overcome limited tissue availability and the “snap shot” problem of omics. These may help in identifying core pathological events and point in directions for focus in clinical prevention.

Gene Expression Profile of Mycobacterium leprae Contribution in the Pathology of Leprosy Neuropathy

Peripheral neuropathy is the main cause of physical disability in leprosy patients. Importantly, the extension and pattern of peripheral damage has been linked to how the host cell will respond against Mycobacterium leprae (M. leprae) infection, in particular, how the pathogen will establish infection in Schwann cells. Interestingly, viable and dead M. leprae have been linked to neuropathology of leprosy by distinct mechanisms. While viable M. leprae promotes transcriptional modifications that allow the bacteria to survive through the use of the host cell's internal machinery and the subvert of host metabolites, components of the dead bacteria are associated with the generation of a harmful nerve microenvironment. Therefore, understanding the pathognomonic characteristics mediated by viable and dead M. leprae are essential for elucidating leprosy disease and its associated reactional episodes. Moreover, the impact of the viable and dead bacteria in Schwann cells is largely unknown and their gene signature profiling has, as yet, been poorly explored. In this study, we analyzed the early differences in the expression profile of genes involved in peripheral neuropathy, dedifferentiation and plasticity, neural regeneration, and inflammation in human Schwann cells challenged with viable and dead M. leprae. We substantiated our findings by analyzing this genetic profiling in human nerve biopsies of leprosy and non-leprosy patients, with accompanied histopathological analysis. We observed that viable and dead bacteria distinctly modulate Schwann cell genes, with emphasis to viable bacilli upregulating transcripts related to glial cell plasticity, dedifferentiation and anti-inflammatory profile, while dead bacteria affected genes involved in neuropathy and pro-inflammatory response. In addition, dead bacteria also upregulated genes associated with nerve support, which expression profile was similar to those obtained from leprosy nerve biopsies. These findings suggest that early exposure to viable and dead bacteria may provoke Schwann cells to behave differentially, with far-reaching implications for the ongoing neuropathy seen in leprosy patients, where a mixture of active and non-active bacteria are found in the nerve microenvironment.

Parental autoimmune and autoinflammatory disorders as multiple risk factors for common neurodevelopmental disorders in offspring: a systematic review and meta-analysis

Epidemiological studies have raised concerns about the risk of neurodevelopmental disorders (NDD) in children of patients with autoimmune or inflammatory disorders (AID). The pathophysiological pathways underlying this association are still unknown and little is known about the specific and distinct risk of each AID. To explore these questions, we investigated the association between the occurrences of several NDD in the offspring of mothers or fathers with different IDA. We conducted a meta-analysis-PROSPERO (CRD42020159250)-examining the risk of NDD in the offspring of mothers or fathers with AID. We performed specific analyses separately in fathers or mothers of NDD patients as well as subgroup analyses for each NDD and AID. We searched MEDLINE, Embase, PsycINFO, Cochrane Central Register of Controlled Trials, and Web of Science Core Collection published until December 2021. From an initial pool of 2074 potentially relevant references, 14 studies were included, involving more than 1,400,000 AID and 10,000,000 control parents, 180,000 children with NDD and more than 14,000,000 control children. We found AID in mothers (Adjusted OR 1.27 [95% CI 1.03; 1.57] p = 0.02, [I² = 65%, Tau² = 0.03 p = 0.01] and adjusted OR 1.31 [95% CI 1.11; 1.55] p = 0.001, [I² = 93%, Tau² = 0.13 p = 0.001] and, although in a lesser extent, in fathers (adjusted OR 1.18 [95% CI 1.07; 1.30] p = 0.01, [I² = 15.5%, Tau² = 0.002 p = 0.47]) and adjusted OR 1.14 [95% CI 1.10; 1.17] p < 0.0001, [I² = 0%, Tau² = 0 p = 0.29]) to be associated with ASD and ADHD in the offspring. This difference in the strength of the association was found in the AID-specific analyses, suggesting that AID increase the risk of NDD by a shared mechanism but that a specific maternal route appears to represent an additional excess risk. Inflammatory bowel disease were not associated with an additional risk (neither in fathers nor in mothers) of NDD in offspring. Our results suggest that complex and multiple AID-specific pathophysiological mechanisms may underlie the association of AID and NDD in offspring. Further, comprehensive studies of the different AID and NDD are needed to draw definitive conclusions about the pathophysiological links between parental AID and NDD in children.

Trans-omics analyses revealed key epigenetic genes associated with overall survival in secondary progressive multiple sclerosis

BACKGROUND

Secondary progressive multiple sclerosis (SPMS) is the second most common presentation of multiple sclerosis (MS) and is characterized by a gradually deteriorating disease with or without relapses. Approximately 80% of patients with relapsing-remitting MS (RRMS) develop SPMS within 20 years. Epidemiological investigations have revealed an average 7-year life expectancy decrease (more severe in progressive subtypes) in patients with MS. Studies have focused on the neurodegenerative pathogenesis of SPMS; and epigenetic changes have been associated with disease progression in neurodegenerative disorders. However, the evidence for the association between epigenetic changes and SPMS is scarce. Thus, in this study we aimed to identify the key epigenetic genes in SPMS.

METHODS

We downloaded DNA methylation and gene expression matrices from the Gene Expression Omnibus (GEO) database. We used bioinformatic analyses to identify key epigenetic genes associated with overall survival (OS) in patients with SPMS.

RESULTS

We found 49 differentially methylated positions (DMPs) between the SPMS and control GSE40360 datasets. We used the wANNOVAR server to obtain 64 methylated genes. We merged the gene expression datasets (GSE131282 and GSE135511) in the NetworkAnalyst platform and found 12,442 differentially-expressed genes (DEGs) between SPMS and controls using the Fisher's method, fixed effect model, Vote counting, and direct merging methods. Moreover, we identified 21 epigenetic genes (all hyper-methylated) after an integrating analysis of DMPs and DEGs of patients with SPMS. We established an epigenetic gene signature associated with the OS of patients with SPMS including six hyper-methylated genes (ITGA6, PPP1R16B, RNF126, ABHD8, FOXK1, and SLC6A19) based on the LASSO-Cox method. The calculated individual risk scores were associated with Oss, and we divided patients into high- and low-risk groups on the basis of the mean cut-off value. The six key epigenetic genes were significantly associated with gender, disease duration, and age at death via Spearman correlation analyses. In addition, survival analyses revealed a significant OS difference between high- and low-risk groups. The ROC curves indicated good performance for this predictive model.

CONCLUSION

We identified 21 hyper-methylated genes in patients with SPMS via an integrated analysis of DNA methylation and gene expression datasets. We identified a six-epigenetic gene signature that predicts the individual OS with good accuracy. These results indicated that epigenetic modifications play a vital role in the disease progression of SPMS.

Dendritic Cell-Targeted Therapies to Treat Neurological Disorders

Dendritic cells (DCs) are the immune system's highly specialized antigen-presenting cells. When DCs are sluggish and mature, self-antigen presentation results in tolerance; however, when pathogen-associated molecular patterns stimulate mature DCs, antigen presentation results in the development of antigen-specific immunity. DCs have been identified in various vital organs of mammals (e.g., the skin, heart, lungs, intestines, and spleen), but the brain has long been thought to be devoid of DCs in the absence of neuroinflammation. However, neuroinflammation is becoming more recognized as a factor in a variety of brain illnesses. DCs are present in the brain parenchyma in trace amounts under healthy circumstances, but their numbers rise during neuroinflammation. New therapeutics are being developed that can reduce dendritic cell immunogenicity by inhibiting pro-inflammatory cytokine production and T cell co-stimulatory pathways. Additionally, innovative ways of regulating dendritic cell growth and differentiation and harnessing their tolerogenic capability are being explored. Herein, we described the function of dendritic cells in neurological disorders and discussed the potential for future therapeutic techniques that target dendritic cells and dendritic cell-related targets in the treatment of neurological disorders.

The influence of HLA-DRB1*15 on the relationship between microglia and neurons in multiple sclerosis normal appearing cortical grey matter

Cortical tissue injury is common in multiple sclerosis (MS) and associates with disability progression. We have previously shown that HLA‐DRB1*15 genotype status associates with the extent of cortical inflammatory pathology. In the current study, we sought to examine the influence of HLA‐DRB1*15 on relationships between inflammation and neurodegeneration in MS. Human post‐mortem MS cases (n = 47) and controls (n = 10) were used. Adjacent sections of motor cortex were stained for microglia (Iba1+, CD68+, TMEM119+), lymphocytes (CD3+, CD8+), GFAP+ astrocytes, and neurons (NeuN+). A subset of MS cases (n = 20) and controls (n = 7) were double‐labeled for neurofilament and glutamic acid decarboxylase 65/67 (GAD+) to assess the extent of the inhibitory synaptic loss. In MS cases, microglial protein expression positively correlated with neuron density (Iba1+: r = 0.548, p < 0.001, CD68+: r = 0.498, p = 0.001, TMEM119+ r = 0.437, p = 0.003). This finding was restricted to MS cases not carrying HLA‐DRB1*15. Evidence of a 14% reduction in inhibitory synapses in MS was detected (MS: 0.299 ± 0.006 synapses/μm² neuronal membrane versus control: 0.348 ± 0.009 synapses/μm² neuronal membrane, p = 0.005). Neurons expressing inhibitory synapses were 24% smaller in MS cases compared to the control (MS: 403 ± 15 μm² versus control: 531 ± 29 μm², p = 0.001), a finding driven by HLA‐DRB1*15+ cases (15+: 376 ± 21 μm² vs. 15−: 432 ± 22 μm², p = 0.018). Taken together, our results demonstrate that HLA‐DRB1*15 modulates the relationship between microglial inflammation, inhibitory synapses, and neuronal density in the MS cortex.

Therapeutic Effects of Physical Exercise and the Mesenchymal Stem Cell Secretome by Modulating Neuroinflammatory Response in Multiple Sclerosis

Multiple sclerosis (MS) is a neurodegenerative, demyelinating, and chronic inflammatory disease characterized by central nervous system (CNS) lesions that lead to high levels of disability and severe physical and cognitive disturbances. Conventional therapies are not enough to control the neuroinflammatory process in MS and are not able to inhibit ongoing damage to the CNS. Thus, the secretome of mesenchymal stem cells (MSC-S) has been postulated as a potential therapy that could mitigate symptoms and disease progression. We considered that its combination with physical exercise (EX) could induce superior effects and increase the MSC-S effectiveness in this condition. Recent studies have revealed that both EX and MSC-S share similar mechanisms of action that mitigate auto-reactive T cell infiltration, regulate the local inflammatory response, modulate the proinflammatory profile of glial cells, and reduce neuronal damage. Clinical and experimental studies have reported that these treatments in an isolated way also improve myelination, regeneration, promote the release of neurotrophic factors, and increase the recruitment of endogenous stem cells. Together, these effects reduce disease progression and improve patient functionality. Despite these results, the combination of these methods has not yet been studied in MS. In this review, we focus on molecular elements and cellular responses induced by these treatments in a separate way, showing their beneficial effects in the control of symptoms and disease progression in MS, as well as indicating their contribution in clinical fields. In addition, we propose the combined use of EX and MSC-S as a strategy to boost their reparative and immunomodulatory effects in this condition, combining their benefits on synaptogenesis, neurogenesis, remyelination, and neuroinflammatory response. The findings here reported are based on the scientific evidence and our professional experience that will bring significant progress to regenerative medicine to deal with this condition.

Identification of immune-associated gene signature and immune cell infiltration related to overall survival in progressive multiple sclerosis

BACKGROUND

Delayed diagnosis and noneffective treatment contribute to the shorter life expectancy in patients with progressive multiple sclerosis (PMS). Studies demonstrate the key role of autoimmunity in PMS, but the prognostic value of immune-associated factors remains unknown. Thus, this study aimed to develop an immune-associated gene (IAG) signature related to overall survival (OS) and conduct an immune cell infiltration analysis using PMS data.

METHODS

The differentially expressed IAGs were identified based on gene expression profiles (from the Gene Expression Omnibus database) and IAGs (from the ImmPort database). Univariate and least absolute shrinkage and selection operator (LASSO)-penalized Cox regression analyses were used to develop the IAG signature related to OS. Kaplan-Meier analyses were conducted, and receiver operating characteristic (ROC) curves were generated to assess the performance. Additionally, the differential distribution of immune cells was identified by Wilcoxon rank-sum tests and correlations with IAGs were analyzed using Spearman correlation analyses. Moreover, univariate and multivariate Cox regression analyses were used to identify the independent prognostic factors to develop a prognostic nomogram.

RESULTS

The training group, consisting of 57 PMS lesions and 52 control tissues, was obtained through batch normalization to remove the inter-batch difference. A total of 206 differentially expressed IAGs were identified, and 38 of them were associated with OS. Thereafter, a 4-IAG signature was constructed to calculate the risk score and thus classify PMS patients into high- and low-risk groups according to mean risk score. Patients in the high-risk group had a lower survival time than those in the low-risk group. The Kaplan-Meier plots and ROC curves demonstrated a good performance in both the training and internal validation groups. Additionally, five differentially abundant immune cell types were identified and their relationships with IAGs were analyzed. Finally, risk score, cortical region, and naive B cells were identified as independent prognostic factors, and a nomogram incorporating these factors was developed to predict the OS in PMS.

CONCLUSION

The novel IAG signature may be a reliable tool for assisting neurologists in predicting the OS for PMS patients in clinical settings. These findings may facilitate personalized treatment and provide insights into the complex mechanism of PMS.

Multiple sclerosis: doubling down on MHC

Human leukocyte antigen (HLA)-encoded surface molecules present antigenic peptides to T lymphocytes and play a key role in adaptive immune responses. Besides their physiological role of defending the host against infectious pathogens, specific alleles serve as genetic risk factors for autoimmune diseases. For multiple sclerosis (MS), an autoimmune disease that affects the brain and spinal cord, an association with the HLA-DR15 haplotype was described in the early 1970s. This short opinion piece discusses the difficulties of disentangling the details of this association and recent observations about the functional involvement of not only one, but also the second gene of the HLA-DR15 haplotype. This information is not only important for understanding the pathomechanism of MS, but also for antigen-specific therapies.

A review of possible therapies for multiple sclerosis

Multiple sclerosis (MS) is an autoimmune chronic inflammatory disease of the central nervous system with a wide range of symptoms, like executive function defect, cognitive dysfunction, blurred vision, decreased sensation, spasticity, fatigue, and other symptoms. This neurological disease is characterized by the destruction of the blood-brain barrier, loss of myelin, and damage to neurons. It is the result of immune cells crossing the blood-brain barrier into the central nervous system and attacking self-antigens. Heretofore, many treatments proved that they can retard the progression of the disease even though there is no cure. Therefore, treatments aimed at improving patients' quality of life and reducing adverse drug reactions and costs are essential. In this review, the treatment approaches to alleviate the progress of MS include the following: pharmacotherapy, antibody therapy, cell therapy, gene therapy, and surgery. The current treatment methods of MS are described in terms of the prevention of myelin shedding, the promotion of myelin regeneration, and the protection of neurons.

HLA-DR15 Molecules Jointly Shape an Autoreactive T Cell Repertoire in Multiple Sclerosis

The HLA-DR15 haplotype is the strongest genetic risk factor for multiple sclerosis (MS), but our understanding of how it contributes to MS is limited. Because autoreactive CD4⁺ T cells and B cells as antigen-presenting cells are involved in MS pathogenesis, we characterized the immunopeptidomes of the two HLA-DR15 allomorphs DR2a and DR2b of human primary B cells and monocytes, thymus, and MS brain tissue. Self-peptides from HLA-DR molecules, particularly from DR2a and DR2b themselves, are abundant on B cells and thymic antigen-presenting cells. Furthermore, we identified autoreactive CD4⁺ T cell clones that can cross-react with HLA-DR-derived self-peptides (HLA-DR-SPs), peptides from MS-associated foreign agents (Epstein-Barr virus and Akkermansia muciniphila), and autoantigens presented by DR2a and DR2b. Thus, both HLA-DR15 allomorphs jointly shape an autoreactive T cell repertoire by serving as antigen-presenting structures and epitope sources and by presenting the same foreign peptides and autoantigens to autoreactive CD4⁺ T cells in MS.

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HLA-DR15 present abundant HLA-DR-derived self-peptides on B cells

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Autoreactive T cells in MS recognize HLA-DR-derived self-peptides/DR15 complexes

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Foreign peptides/DR15 complexes trigger potential autoreactive T cells in MS

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HLA-DR15 shape an autoreactive T cell repertoire by cross-reactivity/restriction