Opposing and potentially antagonistic effects of BMP and TGF-β in multiple sclerosis: The "Yin and Yang" of neuro-immune Signaling

Changes in the Expression of TGF-Beta Regulatory Pathway Genes Induced by Vitamin D in Patients with Relapsing-Remitting Multiple Sclerosis

Vitamin D is an environmental factor related to multiple sclerosis that plays a significant role in immune regulation. TGF-β is a superfamily of cytokines with an important dual effect on the immune system. TGF-β inhibits the Th1 response while facilitating the preservation of regulatory T cells (FOXP3+) in an immunoregulatory capacity. However, when IL-6 is present, it stimulates the Th17 response. Our aim was to analyze the regulatory effect of vitamin D on the in vivo TGF-β signaling pathway in patients with relapsing-remitting multiple sclerosis (RRMS). A total of 21 patients with vitamin D levels < 30 ng/mL were recruited and supplemented with oral vitamin D. All patients were receiving disease-modifying therapy, with the majority being on natalizumab. Expression of SMAD7, ERK1, ZMIZ1, BMP2, BMPRII, BMP4, and BMP5 was measured in CD4+ lymphocytes isolated from peripheral blood at baseline and one and six months after supplementation. SMAD7 was overexpressed at six months with respect to baseline and month one. ERK1 was overexpressed at six months with respect to month one of treatment. No significant differences in expression were observed for the remaining genes. No direct correlation was found with serum vitamin D levels. BMPRII expression changed differentially in non-natalizumab- versus natalizumab-treated patients. Changes were observed in the expression of ERK1, BMP2, and BMP5 based on disease activity measured using the Rio-Score, BMP2 in patients who had relapses, and BMP5 in those whose EDSS worsened. Our results suggest indirect regulation of vitamin D in TGF-β pathway genes in patients with RRMS.

Treatment with 1,25-Dihydroxyvitamin D3 Delays Choroid Plexus Infiltration and BCSFB Injury in MRL/lpr Mice Coinciding with Activation of the PPARγ/NF-κB/TNF-α Pathway and Suppression of TGF-β/Smad Signaling

Neuropsychiatric systemic lupus erythematosus (NPSLE) is a serious complication of systemic lupus erythematosus (SLE) involving the nervous system with high morbidity and mortality. A key hypothesis in NPSLE is that a disrupted barrier allows autoantibodies and immune components of peripheral blood to penetrate into the central nervous system (CNS), resulting in inflammation and damage. The blood cerebrospinal fluid barrier (BCSFB), which consists of the choroid plexus and the hypothalamic tanycytes, has long been regarded as an immunological sanctuary site. 1,25-Dihydroxyvitamin D3 [1,25-(OH)₂D₃] is the active form of vitamin D, which plays multiple roles in inflammation and immunoregulation. In this study, we investigated the possible protective effects of 1,25-dihydroxyvitamin D3 against BCSFB dysfunction in NPSLE in MRL/lpr mice and explored the mechanism by which 1,25-dihydroxyvitamin D3 inhibits the progression of NPSLE. In this study, we found that supplementation with 1,25-dihydroxyvitamin D3 markedly improved serological and immunological indices, delayed inflammatory infiltration, delayed neuronal deformation, and upregulated the expression of brain-derived neurotrophic factor (BDNF) proteins in the brain. Furthermore, 1,25-dihydroxyvitamin D3 downregulated proinflammatory cytokines such as nuclear factor kappa-B (NF-κB) and tumor necrosis factor-α (TNF-α) by activating peroxisome proliferator-activated receptor γ (PPARγ), and it reduced the expression of the TGF-β/Smad signaling pathway. Our findings demonstrate that 1,25-dihydroxyvitamin D3 delayed cell infiltration into the choroid plexus and decreased markers suggestive of cognitive decline in MRL/lpr mice, and the mechanism may be related to protection against BCSFB disruption through activation of the anti-inflammatory PPARγ/NF-κB/TNF-α pathway as well as upregulation of BDNF and inhibition of the TGF-β/Smad signaling pathway. These findings provide a novel direction for the study of NPSLE.

[A comparison of DNA methylation profiles of blood mononuclear cells in patients with multiple sclerosis in remission and relapse]

OBJECTIVE

To study the whole-genome DNA methylation profiles of peripheral blood mononuclear blood cells (PBMCs) of patients with relapsing-remitting multiple sclerosis (RRMS) in remission and relapse in order to assess the contribution of this epigenetic mechanism of gene expression regulation to the activity of the pathological process.

MATERIAL AND METHODS

Eight patients with RRMS in remission and 6 patients in relapse were included in the study. Methylation levels of DNA CpG sites in PBMCs were analyzed using Infinium HumanMethylation450 BeadChip DNA microarrays.

RESULTS

Seven differentially methylated positions (DMPs) were identified, of which 3 were hypermethylated (cg02981003, cg18486102, cg19533582) and 4 were hypomethylated (cg16814680, cg1964802, cg18584440, cg08291996) during RRMS relapse. Five DMPs are located in protein-coding genes (GPR123, FAIM2, BTNL2, ZNF8, ASAP2), one in microRNA gene (MIR548N), and one in an intergenic region. For all identified DMPs, we observed a change in DNA methylation levels of more than 20% (range 20.2-57.5%). Hierarchical clustering of DNA samples on the heatmap shows their clear aggregation into separate clusters corresponding to RRMS patients in the stages of relapse and remission.

CONCLUSION

For the first time it was shown that during relapse and remission of RRMS there are differences in the DNA methylation profile that allow discrimination between these clinical stages. These data indicate the involvement of the epigenetic mechanism of DNA methylation in the activation of the pathological process in RRMS.

Wound healing in aged skin exhibits systems-level alterations in cellular composition and cell-cell communication

Delayed and often impaired wound healing in the elderly presents major medical and socioeconomic challenges. A comprehensive understanding of the cellular/molecular changes that shape complex cell-cell communications in aged skin wounds is lacking. Here, we use single-cell RNA sequencing to define the epithelial, fibroblast, immune cell types, and encompassing heterogeneities in young and aged skin during homeostasis and identify major changes in cell compositions, kinetics, and molecular profiles during wound healing. Our comparative study uncovers a more pronounced inflammatory phenotype in aged skin wounds, featuring neutrophil persistence and higher abundance of an inflammatory/glycolytic Arg1^Hi macrophage subset that is more likely to signal to fibroblasts via interleukin (IL)-1 than in young counterparts. We predict systems-level differences in the number, strength, route, and signaling mediators of putative cell-cell communications in young and aged skin wounds. Our study exposes numerous cellular/molecular targets for functional interrogation and provides a hypothesis-generating resource for future wound healing studies.

Identification of Novel Key Genes and Pathways in Multiple Sclerosis Based on Weighted Gene Coexpression Network Analysis and Long Noncoding RNA-Associated Competing Endogenous RNA Network

Objective

Multiple sclerosis (MS) is an autoimmune disease of the central nervous system characterized by chronic inflammation and demyelination. This study is aimed at identifying crucial genes and molecular pathways involved in MS pathogenesis.

Methods

Raw data in GSE52139 were collected from the Gene Expression Omnibus. The top 50% expression variants were subjected to weighted gene coexpression network analysis (WGCNA), and the key module associated with MS occurrence was identified. A long noncoding RNA- (lncRNA-) associated competing endogenous RNA (ceRNA) network was constructed in the key module. The hub gene candidates were subsequently verified in an individual database.

Results

Of the 18 modules obtained, the cyan module was designated as the key module. The established ceRNA network was composed of seven lncRNAs, 45 mRNAs, and 21 microRNAs (miRNAs), and the FAM13A-AS1 was the lncRNA with the highest centrality. Functional assessments indicated that the genes in the cyan module primarily gathered in ribosome-related functional terms. Interestingly, the targeted mRNAs of the ceRNA network enriched in diverse categories. Moreover, highly expressed CYBRD1, GNG12, and SMAD1, which were identified as hub genes, may be associated with “valine leucine and isoleucine degradation,” “base excision repair,” and “fatty acid metabolism,” respectively, according to the results of single gene-based genomes and gene set enrichment analysis (GSEA).

Conclusions

Combined with the WGCNA and ceRNA network, our findings provide novel insights into the pathogenesis of MS. The hub genes discovered herein might also serve as novel biomarkers that correlate with the development and management of MS.

BMP/TGF-β signaling as a modulator of neurodegeneration in ALS

This commentary focuses on the emerging intersection between BMP/TGF-β signaling roles in nervous system function and the amyotrophic lateral sclerosis (ALS) disease state. Future research is critical to elucidate the molecular underpinnings of this intersection of the cellular processes disrupted in ALS and those influenced by BMP/TGF-β signaling, including synapse structure, neurotransmission, plasticity, and neuroinflammation. Such knowledge promises to inform us of ideal entry points for the targeted modulation of dysfunctional cellular processes in an effort to abrogate ALS pathologies. It is likely that different interventions are required, either at discrete points in disease progression, or across multiple dysfunctional processes which together lead to motor neuron degeneration and death. We discuss the challenging, but intriguing idea that modulation of the pleiotropic nature of BMP/TGF-β signaling could be advantageous, as a way to simultaneously treat defects in more than one cell process across different forms of ALS.