Cholesterol-dependent LXR transcription factor activity represses pronociceptive effects of estrogen in sensory neurons and pain induced by myelin basic protein fragments.

Background: A bioactive myelin basic protein (MBP) fragment, comprising MBP84-104, is released in sciatic nerve after chronic constriction injury (CCI). Intraneural injection (IN) of MBP84-104 in an intact sciatic nerve is sufficient to induce persistent neuropathic pain-like behavior via robust transcriptional remodeling at the injection site and ipsilateral dorsal root ganglia (DRG) and spinal cord. The sex (female)-specific pronociceptive activity of MBP84-104 associates with sex-specific changes in cholesterol metabolism and activation of estrogen receptor (ESR)1 signaling. Methods: In male and female normal and post-CCI rat sciatic nerves, we assessed: (i) cholesterol precursor and metabolite levels by lipidomics; (ii) MBP84-104 interactors by mass spectrometry of MBP84-104 pull-down; and (iii) liver X receptor (LXR)α protein expression by immunoblotting. To test the effect of LXRα stimulation on IN MBP84-104-induced mechanical hypersensitivity, the LXRα expression was confirmed along the segmental neuraxis, in DRG and spinal cord, followed by von Frey testing of the effect of intrathecally administered synthetic LXR agonist, GW3965. In cultured male and female rat DRGs exposed to MBP84-104 and/or estrogen treatments, transcriptional effect of LXR stimulation by GW3965 was assessed on downstream cholesterol transporter Abc, interleukin (IL)-6, and pronociceptive Cacna2d1 gene expression. Results: CCI regulated LXRα ligand and receptor levels in nerves of both sexes, with cholesterol precursors, desmosterol and 7-DHC, and oxysterol elevated in females relative to males. MBP84-104 interacted with nuclear receptor coactivator (Ncoa)1, known to activate LXRα, injury-specific in nerves of both sexes. LXR stimulation suppressed ESR1-induced IL-6 and Cacna2d1 expression in cultured DRGs of both sexes and attenuated MBP84-104-induced pain in females. Conclusion: The injury-released bioactive MBP fragments induce pronociceptive changes by selective inactivation of nuclear transcription factors, including LXRα. By Ncoa1 sequestration, bioactive MBP fragments render LXRα function to counteract pronociceptive activity of estrogen/ESR1 in sensory neurons. This effect of MBP fragments is prevalent in females due to high circulating estrogen levels in females relative to males. Restoring LXR activity presents a promising therapeutic strategy in management of neuropathic pain induced by bioactive MBP.

The restoration of hippocampal nerve de-myelination by methylcobalamin relates with the enzymatic regulation of homocysteine level in a rat model of moderate grade hepatic encephalopathy.

This article describes how methylcobalamin (MeCbl) restores nerve myelination in a moderate- grade hepatic encephalopathy (MoHE) model of ammonia neurotoxicity. The comparative profiles of myelin basic protein (MBP), homocysteine (Hcy) and methionine synthase (MS: a MeCbl- dependent enzyme) activity versus nerve myelination status were studied in the hippocampus of the control, the MoHE (developed by administering 100 mg/kg bw thioacetamide i.p. for 10 days) and the MoHE rats treated with MeCbl (500 µg/kg BW i.p.) for 7 days. Compared to those of control rats, the hippocampal CA1 and CA3 regions of the MoHE rats showed significantly lower myelinated areas and MBP immunostaining. This coincided with the deranged myelin layering in TEM images, decreased MBP protein and its transcript levels in hippocampus of MoHE rats. However, all these parameters recovered to normal levels after MeCbl treatment. MeCbl is a cofactor of MS that catalyzes the conversion of Hcy to methionine as a feeder step of methylation reactions. We observed significantly increased serum and hippocampal Hcy levels in MoHE rats, however, these levels were restored to control values with a concordant activation of MS due to MeCbl treatment. A significant recovery in neurobehavioral impairments in the MoHE rats due to MeCbl treatment was also observed. These findings suggest that MoHE pathogenesis is associated with deranged nerve myelination in the hippocampus and that MeCbl treatment is able to restore it mainly by activating MS, a MeCbl-dependent Hcy-metabolizing enzyme.

Myelin Basic Protein Attenuates Furin-Mediated Bri2 Cleavage and Postpones Its Membrane Trafficking.

Myelin basic protein (MBP) is the second most abundant protein in the central nervous system and is responsible for structural maintenance of the myelin sheath covering axons. Previously, we showed that MBP has a more proactive role in the oligodendrocyte homeostasis, interacting with membrane-associated proteins, including integral membrane protein 2B (ITM2B or Bri2) that is associated with familial dementias. Here, we report that the molecular dynamics of the in silico-generated MBP-Bri2 complex revealed that MBP covers a significant portion of the Bri2 ectodomain, assumingly trapping the furin cleavage site, while the surface of the BRICHOS domain, which is responsible for the multimerization and activation of the Bri2 high-molecular-weight oligomer chaperone function, remains unmasked. These observations were supported by the co-expression of MBP with Bri2, its mature form, and disease-associated mutants, which showed that in mammalian cells, MBP indeed modulates the post-translational processing of Bri2 by restriction of the furin-catalyzed release of its C-terminal peptide. Moreover, we showed that the co-expression of MBP and Bri2 also leads to an altered cellular localization of Bri2, restricting its membrane trafficking independently of the MBP-mediated suppression of the Bri2 C-terminal peptide release. Further investigations should elucidate if these observations have physiological meaning in terms of Bri2 as a MBP chaperone activated by the MBP-dependent postponement of Bri2 membrane trafficking.

Effects of acrylamide exposure during pregnancy and lactation on the development of myelin sheath of corpus callosum in offspring rats.

Acrylamide is an alkene known to induce neurotoxicity in humans and experimental animals. However, the effects of acrylamide on the development of myelin sheath are unclear. The present study was to explore the effects of acrylamide exposure during pregnancy and lactation on the development of myelin sheath in offspring rats. Four groups of thirty-two pregnant Sprague-Dawley rats were exposed to 0, 4.5, 9 and 18 mg/kg BW acrylamide by gavage from gestational day 15 to postnatal day 13. The corpus callosum of nine offspring rats per group were dissected in postpartum day 14. Structural changes and lipid contents in myelin sheaths were examined by transmission electron microscopy(TEM) and Luxol Fast Blue staining(LFB). The expression of MBP and PLP was evaluated by immunohistochemistry and Western blotting. TEM showed that the myelin sheaths in the 18 mg/kg group were disordered compared with control group. Luxol Fast Blue staining gradually decreased with increasing acrylamide maternal exposure. The immunohistochemistry and Western Blotting results showed that maternal exposure to acrylamide caused a decreasing trend in MBP and PLP in the corpus callosum of rats at postnatal day 14. Furthermore, these reduced protein levels may be neurodevelopmental toxicity's mechanism in response to maternal exposure to acrylamide.

5ß-reduced neuroactive steroids as modulators of growth and viability of postnatal neurons and glia.

Endogenous neurosteroids (NS) and their synthetic analogs, neuroactive steroids (NAS), are potentially useful drug-like compounds affecting the pathophysiology of miscellaneous central nervous system disorders (e.g. Alzheimer´s disease, epilepsy, depression, etc.). Additionally, NS have been shown to promote neuron viability and neurite outgrowth upon injury. The molecular, structural and physicochemical basis of the NS effect on neurons is so far not fully understood, and the development of new, biologically relevant assays is essential for their comparative analysis and for assessment of their mechanism of action. Here, we report the development of a novel, plate-based, high-content in vitro assay for screening of NS and newly synthesized, 5ß-reduced NAS for the promotion of postnatal neuron survival and neurite growth using fluorescent, postnatal mixed cortical neuron cultures isolated from thy1-YFP transgenic mice. The screen allows a detailed time course analysis of different parameters, such as the number of neurons or neurite lengths of 7-day, in vitro neuron cultures. Using the screen, we identify a new NAS, compound 42, that promotes the survival and growth of postnatal neurons significantly better than several endogenous NS (dehydroepiandrosterone, progesterone, and allopregnanolone). Interestingly, we demonstrate that compound 42 also promotes the proliferation of glia (in particular oligodendrocytes) and that the glial function is critical for its neuron growth support. Computational analysis of the biological data and calculated physicochemical properties of tested NS and NAS demonstrated that their biological activity is proportional to their lipophilicity. Together, the screen proves useful for the selection of neuron-active NAS and the comparative evaluation of their biologically relevant structural and physicochemical features.

Citrullinated isomer of myelin basic protein can induce inflammatory responses in astrocytes.

Purpose: During the course of demyelinating inflammatory diseases, myelin-derived proteins, including myelin basic protein(MBP), are secreted into extracellular space. MBP shows extensive post-translational modifications, including deimination/citrullination. Deiminated MBP is structurally less ordered, susceptible to proteolytic attack, and more immunogenic than unmodified MBP. This study investigated the effect of the deiminated/citrullinated isomer of MBP(C8) and the unmodified isomer of MBP(C1) on cultured primary astrocytes. Methods: MBP charge isomers were isolated/purified from bovine brain. Primary astrocyte cultures were prepared from the 2-day-old Wistar rats. For evaluation of glutamate release/uptake a Fluorimetric glutamate assay was used. Expression of peroxisome proliferator-activated receptor-gamma(PPAR-γ), excitatory amino acid transporter 2(EAAT2), the inhibitor of the nuclear factor kappa-B(ikB) and high mobility group-B1(HMGB1) protein were assayed by Western blot analysis. IL-17A expression was determined in cell medium by ELISA. Results: We found that MBP(C8) and MBP(C1) acted differently on the uptake/release of glutamate in astrocytes: C1 increased glutamate uptake and did not change its release, whereas C8 decreased glutamate release but did not change its uptake. Both isomers increased the expression of PPAR-γ and EAAT2 to the same degree. Western blots of cell lysates revealed decreased expression of ikB and increased expression of HMGB1 proteins after treatment of astrocytes by C8. Moreover, C8-treated cells released more nitric oxide and proinflammatory IL-17A than C1-treated cells. Conclusions: These data suggest that the most immunogenic deiminated isomer C8, in parallel to the decreases in glutamate release, elicits an inflammatory response and enhances the secretion of proinflammatory molecules via activation of nuclear factor kappa B(NF-kB). Summary statement: The most modified-citrullinated myelin basic protein charge isomer decreases glutamate release, elicits an inflammatory response and enhances the secretion of proinflammatory molecules via activation of nuclear factor kappa B in astrocytes.

Phase-Dependent Adsorption of Myelin Basic Protein to Phosphatidylcholine Lipid Bilayers.

The dense packing of opposite cytoplasmic surfaces of the lipid-enriched myelin membrane, responsible for the proper saltatory conduction of nerve impulses through axons, is ensured by the adhesive properties of myelin basic protein (MBP). Although preferentially interacting with negatively charged phosphatidylserine (PS) lipids, as an intrinsically disordered protein, it can easily adapt its shape to its immediate environment and thus adsorb to domains made of zwitterionic phosphatidylcholine (PC) lipids. As the molecular-level interaction pattern between MBP and PC lipid membranes suffers from scarce characterization, an experimental and computational study of multilamellar liposomes (MLVs) composed of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) in the presence of bovine MBP is presented here. Calorimetric and temperature-dependent UV-Vis measurements identified DPPC pretransition temperature (Tp) and calorimetric enthalpy (ΔHcal) as the physicochemical parameters most responsive to the presence of MBP. Besides suggesting an increase in ß-sheet fractions of structured MBP segments as DPPC lipids undergo from the gel (20 °C) to the fluid (50 °C) phase, FTIR spectra unraveled the significant contribution of lysine (Lys) residues in the adsorption pattern, especially when DPPC is in the fluid (50 °C) phase. In addition to highlighting the importance of Lys residues in the MBP adsorption on DPPC lipid bilayer, employing salt bridges (SBs) and hydrogen bonds (HBs), MD data suggest the crucial importance of the orientation of MBP with respect to the surface of the DPPC lipid bilayer.

Serum tau protein and myelin basic protein in pediatric patients with congenital heart defects undergoing cardiac surgery: preliminary assessment as novel neuromarkers of brain injury.

INTRODUCTION: Neurological impairment is a big concern in the development of patients with congenital heart defects (CHD). A number of neuromarkers have been studied in search of a diagnostic or prognostic marker for brain injury during the vulnerable perioperative period. Our aim was to assess two novel neuromarkers, myelin basic protein (MBP) and protein Tau (pTau), as diagnostic markers for brain injury in perioperative period in children with CHD. METHODS: Forty patients were enrolled and dichotomized based on peripheric oxygen saturation in cyanotic and non-cyanotic group. Blood samples were collected preoperative, after the induction of anesthesia, and in postoperative day 1. Neuromarker concentrations were measured using commercially available ELISA kits. RESULTS: Neuromarkers' values were increased postoperative, with statistical significance reached only in non-cyanotic group (p < 0.0001). A significant positive correlation was observed between preoperatory MBP and albumin level, hemoglobin level, height, and weight of patients. Association with cerebral saturations were analyzed by a coefficient defined as ≥ 20% reduction in cerebral saturation measured by near-infrared spectroscopy during perioperative period. An acceptable predicting model was observed with pTau in cyanotic group (AUC = 0.7). CONCLUSION: We evaluated MBP and pTau as potential biomarkers of brain injury in children with CHD undergoing cardiac surgery. Elevated postoperative pTau and MBP concentrations were observed in both groups. Elevated pTau values were associated with perioperative hypoxemia.

Corrigendum: Treatment of surgical brain injury by immune tolerance induced by peripheral intravenous injection of biotargeting nanoparticles loaded with brain antigens.

[This corrects the article DOI: 10.3389/fimmu.2019.00743.].

Role of Specific Autoantibodies in Neurodegenerative Diseases: Pathogenic Antibodies or Promising Biomarkers for Diagnosis.

Neurodegenerative diseases (NDDs) affect millions of people worldwide. They develop due to the pathological accumulation and aggregation of various misfolded proteins, axonal and synaptic loss and dysfunction, inflammation, cytoskeletal abnormalities, defects in DNA and RNA, and neuronal death. This leads to the activation of immune responses and the release of the antibodies against them. Recently, it has become clear that autoantibodies (Aabs) can contribute to demyelination, axonal loss, and brain and cognitive dysfunction. This has significantly changed the understanding of the participation of humoral autoimmunity in neurodegenerative disorders. It is crucial to understand how neuroinflammation is involved in neurodegeneration, to aid in improving the diagnostic and therapeutic value of Aabs in the future. This review aims to provide data on the immune system's role in NDDs, the pathogenic role of some specific Aabs against molecules associated with the most common NDDs, and their potential role as biomarkers for monitoring and diagnosing NDDs. It is suggested that the autoimmune aspects of NDDs will facilitate early diagnosis and help to elucidate previously unknown aspects of the pathobiology of these diseases.

[Effects of propofol on myelin basic protein expression in zebrafish at different developmental stages].

OBJECTIVE: To observe the effect of propofol on the expression of myelin basic protein (MBP) in developing zebrafish and explore the possible mechanisms. METHODS: A total of 180 zebrafish embryos at 6-48 h post-fertilization were randomly allocated into 3 equal groups and raised in fresh water (control group), water containing dimethyl sulfoxide (DMSO group) and water containing 30 µg/mL propofol (propofol group). On 3, 4, 5, 6, 7, 10 d post-fertilization, the juvenile fish were collected for detection of mRNA and protein expressions of MBP using RT-qPCR and Western blotting. TUNEL assay and immunofluorescence assay were used to detect apoptosis of the oligodendrocytes of the fish at 3 d post-fertilization; RT-qPCR and Western blotting were performed to detect the expressions of apoptosis-related factors caspase-8, caspase-9 and caspase-3. RESULTS: Compared with the control group, the fish with propofol exposure showed significantly decreased mRNA and protein expression of MBP at 3-7 d post-fertilization (P<0.05) with increased apoptosis of the oligodendrocytes and upregulated expressions of caspase-8, caspase-9 and caspase-3 at both the mRNA and protein levels. CONCLUSION: Propofol persistently inhibits MBP expression in developing zebrafish within a short term possibly by mediating apoptosis of the oligodendrocytes.

Engineering chimeric autoantibody receptor T cells for targeted B cell depletion in multiple sclerosis model: An in-vitro study.

Background: Recent evidence suggests that B cells and autoantibodies have a substantial role in the pathogenesis of Multiple sclerosis. T cells could be engineered to express chimeric autoantibody receptors (CAARs), which have an epitope of autoantigens in their extracellular domain acting as bait for trapping autoreactive B cells. This study aims to assess the function of designed CAAR T cells against B cell clones reactive to the myelin basic protein (MBP) autoantigen. Methods: T cells were transduced to express a CAAR consisting of MBP as the extracellular domain. experimental autoimmune encephalomyelitis (EAE) was induced by injecting MBP into mice. The cytotoxicity, proliferation, and cytokine production of the MBP-CAAR T cells were investigated in co-culture with B cells. Results: MBP-CAAR T cells showed higher cytotoxic activity against autoreactive B cells in all effector-to-target ratios compared to Mock T cell (empty vector-transduced T cell) and Un-T cells (un-transduced T cell). In co-cultures containing CAAR T cells, there was more proliferation and inflammatory cytokine release as compared to Un-T and Mock T cell groups. Conclusion: Based on these findings, CAAR T cells are promising for curing or modulating autoimmunity and can be served as a new approach for clone-specific B cell depletion therapy in multiple sclerosis.

Multiple sclerosis: new insights into molecular pathogenesis and novel platforms for disease treatment.

BACKGROUND: Multiple sclerosis (MS), a chronic inflammatory disorder, affects the central nervous system via myelin degradation. The cause of MS is not fully known, but during recent years, our knowledge has deepened significantly regarding the different aspects of MS, including etiology, molecular pathophysiology, diagnosis and therapeutic options. Myelin basic protein (MBP) is the main myelin protein that accounts for maintaining the stability of the myelin sheath. Recent evidence has revealed that MBP citrullination or deamination, which is catalyzed by Ca2+ dependent peptidyl arginine deiminase (PAD) enzyme leads to the reduction of positive charge, and subsequently proteolytic cleavage of MBP. The overexpression of PAD2 in the brains of MS patients plays an essential role in new epitope formation and progression of the autoimmune disorder. Some drugs have recently entered phase III clinical trials with promising efficacy and will probably obtain approval in the near future. As different therapeutic platforms develop, finding an optimal treatment for each individual patient will be more challenging. AIM: This review provides a comprehensive insight into MS with a focus on its pathogenesis and recent advances in diagnostic methods and its present and upcoming treatment modalities. CONCLUSION: MS therapy alters quickly as research findings and therapeutic options surrounding MS expand. McDonald's guidelines have created different criteria for MS diagnosis. In recent years, ever-growing interest in the development of PAD inhibitors has led to the generation of many reversible and irreversible PAD inhibitors against the disease with satisfactory therapeutic outcomes.

Serum Levels of S100B Protein and Myelin Basic Protein as a Potential Biomarkers of Recurrent Depressive Disorders.

Nowadays, nervous tissue damage proteins in serum are considered promising drug targets and biomarkers of Mood Disorders. In a cross-sectional naturalistic study, the S100B, MBP and GFAP levels in the blood serum were compared between two diagnostic groups (patients with Depressive Episode (DE, n = 28) and patients with Recurrent Depressive Disorder (RDD, n = 21)), and healthy controls (n = 25). The diagnostic value of serum markers was assessed by ROC analysis. In the DE group, we did not find changed levels of S100B, MBP and GFAP compared with controls. In the RDD group, we found decreased S100B level (p = 0.011) and increased MBP level (p = 0.015) in comparison to those in healthy controls. Provided ROC analysis indicates that MBP contributes to the development of a DE (AUC = 0.676; 95%Cl 0.525-0.826; p = 0.028), and S100B and MBP have a significant effect on the development of RDD (AUC = 0.732; 95%Cl 0.560-0.903; p = 0.013 and AUC = 0.712; 95%Cl 0.557-0.867; p = 0.015, correspondingly). The study of serum markers of nervous tissue damage in patients with a current DE indicates signs of disintegration of structural and functional relationships, dysfunction of gliotransmission, and impaired secretion of neurospecific proteins. Modified functions of astrocytes and oligodendrocytes are implicated in the pathophysiology of RDD.

Retrospective study on the correlation between serum MIF level and the condition and prognosis of patients with traumatic head injury.

Objective: This study aimed to investigate the correlation between serum levels of macrophage migration inhibitory factor (MIF) and the condition and prognosis of patients with traumatic brain injury (TBI). Methods: A retrospective study design was used, and the clinical data of 131 TBI patients from February 2019 to January 2022 were analyzed. Patients were divided into mild (13-15 points), moderate (9-12 points), or severe (3-8 points) groups according to their Glasgow Coma Scale (GCS) score after admission. The serum levels of BDNF, MIF, and MBP in the three groups were compared, and their correlation with the severity of TBI was analyzed. Patients were then separated into a good prognosis group (4-5 points) and a poor prognosis group (≤3 points) based on their Glasgow Prognostic Score (GOS) after 6 months of follow-up. The predictive power of serum indexes and combined detection on prognosis was analyzed. Results: Patients were classified into a mild group (n = 63), moderate group (n = 47), and severe group (n = 21) based on their GCS, with a significant difference noted in serum levels of MIF, MBP, and BDNF among patients with different degrees of severity (all P < 0.001). The MIF, MBP, and BDNF levels were lower in the mild group compared to the moderate (all P < 0.001) and severe group (all P < 0.001). Additionally, the MIF and BDNF levels in the moderate group were lower compared to the severe group (P = 0.011, P = 0.002). Patients with mild severity had lower serum MIF, MBP, and BDNF levels than those with other degrees, and these indexes were positively correlated with the severity of TBI (all P < 0.001, r = 0.62, r = 0.48, r = 0.58). Based on the GOS, patients were divided into a good prognosis group (n = 107) and a poor prognosis group (n = 24), with the levels of MIF, MBP, and BDNF in the good prognosis group being significantly lower than those in the poor prognosis group (P < 0.001, P = 0.007, P = 0.003). The area under the curve (AUC) of MIF was higher than that of MBP and BDNF in predicting the prognosis of TBI patients; however, the statistical differences were not significant (MIF vs. MBP, P = 0.239; MIF vs. BDNF, P = 0.211; BDNF vs. MBP, P = 0.899). The center line has a large displacement, CT annular cisterna compression, increased white blood cell count, MBP and BDNF were risk factors for prognosis in TBI patients (P = 0.005, P = 0.001, P = 0.005, P = 0.033, P = 0.044). Conclusion: The serum levels of MIF, MBP, and BDNF in TBI patients were positively correlated with the severity of the disease, and MBP, BDNF levels had predictive value in determining patient prognosis.

Characterization of membrane-interaction mechanisms of proteins using vacuum-ultraviolet circular dichroism spectroscopy.

Protein-membrane interactions play an important role in various biological phenomena, such as material transport, demyelinating diseases, and antimicrobial activity. We combined vacuum-ultraviolet circular dichroism (VUVCD) spectroscopy with theoretical (e.g., molecular dynamics and neural networks) and polarization experimental (e.g., linear dichroism and fluorescence anisotropy) methods to characterize the membrane interaction mechanisms of three soluble proteins (or peptides). α1 -Acid glycoprotein has the drug-binding ability, but the combination of VUVCD and neural-network method revealed that the membrane interaction causes the extension of helix in the N-terminal region, which reduces the binding ability. Myelin basic protein (MBP) is an essential component of the myelin sheath with a multi-layered structure. Molecular dynamics simulations using a VUVCD-guided system showed that MBP forms two amphiphilic and three non-amphiphilic helices as membrane interaction sites. These multivalent interactions may allow MBP to interact with two opposing membrane leaflets, contributing to the formation of a multi-layered myelin structure. The antimicrobial peptide magainin 2 interacts with the bacterial membrane, causing damage to its structure. VUVCD analysis revealed that the M2 peptides assemble in the membrane and turn into oligomers with a ß-strand structure. Linear dichroism and fluorescence anisotropy suggested that the oligomers are inserted into the hydrophobic core of the membrane, disrupting the bacterial membrane. Overall, our findings demonstrate that VUVCD and its combination with theoretical and polarization experimental methods pave the way for unraveling the molecular mechanisms of biological phenomena related to protein-membrane interactions.

Citrullination of myelin basic protein induces a Th17-cell response in healthy individuals and enhances the presentation of MBP85-99 in patients with multiple sclerosis.

The post-translational modification citrullination has been proposed to play a role in the pathogenesis of multiple sclerosis (MS). Myelin basic protein (MBP) is a candidate autoantigen which is citrullinated to a minor extent under physiological conditions and hypercitrullinated in MS. We examined immune cell responses elicited by hypercitrullinated MBP (citMBP) in cultures of mononuclear cells from 18 patients with MS and 42 healthy donors (HDs). The immunodominant peptide of MBP, MBP85-99, containing citrulline in position 99, outcompeted the binding of native MBP85-99 to HLA-DR15, which is strongly linked to MS. Moreover, using the monoclonal antibody MK16 as probe, we observed that B cells and monocytes from HLA-DR15+ patients with MS presented MBP85-99 more efficiently after challenge with citMBP than with native MBP. Both citMBP and native MBP induced proliferation of CD4+ T cells from patients with MS as well as TNF-α production by their B cells and CD4+ T cells, and citrullination of MBP tended to enhance TNF-α secretion by CD4+ T cells from HLA-DR15+ patients. Unlike native MBP, citMBP induced differentiation into Th17 cells in cultures from HDs, while neither form of MBP induced Th17-cell differentiation in cultures from patients with MS. These data suggest a role for citrullination in the breach of tolerance to MBP in healthy individuals and in maintenance of the autoimmune response to MBP in patients with MS.

Structural dynamics of moonlighting intrinsically disordered proteins - A black box in multiple sclerosis.

Multiple Sclerosis (MS) is a demyelinating disease of the central nervous system that disturbs the flow of brain signals to other parts of the body. The actual cause of the disease is still not apparent. The intrinsically disordered proteins (IDP) play a crucial role in neurodegenerative diseases like Alzheimer's, Lewy bodies, Parkinson's, Amyotrophic Lateral Sclerosis, Multiple Sclerosis, etc. In MS, it was known that the immune system attacks the proteins like Myelin Basic Protein (MBP), Myelin-associated Oligodendrocyte Basic protein (MOBP), Myelin-Associated Protein (MAG), and Myelin Proteolipid Protein (PLP) and this leads to demyelination causing MS. Here the proteins MBP and MOBP are both moonlighting intrinsically disordered proteins and exist between the myelin sheath, unlike MAG which is a transmembrane protein. The main focus of the article was to examine the significant role of proteins intrinsically disordered regions (IDR) in maintaining their function. Molecular dynamics simulation studies were performed to study the conformational dynamics of these protein IDRs both in water and near the myelin sheath. The results suggest that the IDR dominates the structural dynamics of these proteins and IDR in both proteins was responsible for their interaction with the myelin sheath. Interestingly, it was noted that the known epitopes MBP83-96 and MOBP65-87 in the IDR have no interaction with the myelin sheath. Thus when the protein remains intrinsically disordered it maintains the proper function and myelin integrity and if it adopts folds the region was identified as an epitope by the immune system leading to demyelination causing MS.

Some structural features of the peptide profile of myelin basic protein-hydrolyzing antibodies in schizophrenic patients.

The antibodies of schizophrenic patients that hydrolyze myelin basic protein (MBP) have been actively studied recently, but the mechanism of the catalytic properties of immunoglobulin molecules remains unknown. Determination of specific immunoglobulin sequences associated with the high activity of MBP proteolysis will help to understand the mechanisms of abzyme catalysis. In the course of comparative mass spectrometric analysis of IgG peptides from the blood serum of patients with acute schizophrenia and healthy people, 12 sequences were identified, which were found only in antibodies that hydrolyze MBP. These sequences belong to IgG heavy chains and κ- and λ-type light chains, with eight of them belonging to variable domains. The content of peptides from the variable regions of the light chains does not correlate with the proteolytic activity of IgG to MBP in patients with schizophrenia, whereas for two sequences from the variable regions of the heavy chains (FQ(+0.98)GWVTMTR and *LYLQMN(+0.98)SLR), an increase in activity with increasing their concentration. The results suggest that these sequences may be involved in one way or another in MBP hydrolysis.

Tehranolid and Artemisinin Effects on Ameliorating Experimental Autoimmune Encephalomyelitis by Modulating Inflammation and Remyelination.

Multiple sclerosis (MS) is an autoimmune demyelinating disease of the central nervous system. Artemisinin (ART) is a natural sesquiterpene lactone with an endoperoxide bond that is well-known for its anti-inflammatory effects in experimental autoimmune encephalomyelitis (EAE), the most commonly used animal model of MS. Tehranolide (TEH) is a novel compound with structural similarity to ART. In this study, we aimed to investigate the ameliorating effect of TEH on EAE development by targeting proteins and genes involved in this process and compare its effects with ART. Female C57BL/6 mice were immunized with MOG35-55. Twelve days post-immunization, mice were treated with 0.28 mg/kg/day TEH and 2.8 mg/kg/day ART for 18 consecutive days, and the clinical score was measured daily. The levels of pro-inflammatory and anti-inflammatory cytokines were assessed in mice serum and splenocytes by ELISA. We also evaluated the mRNA expression level of cytokines, as well as genes involved in T cell differentiation and myelination in the spinal cord tissue by qRT-PCR. Administration of TEH and ART significantly alleviated EAE signs. A significant reduction in IL-6 and IL-17 secretion and IL-17 and IL-1 gene expression in spinal cord were observed in the TEH-treated group. ART had similar or less significant effects. Moreover, TGF-ß, IL-4, and IL-10 genes were stimulated by ART and TEH in the spinal cord, while the treatments did not affect IFN-γ expression. Both treatments dramatically increased the expression of FOXP3, GATA3, MBP, and AXL. Additionally, the T-bet gene was reduced after TEH administration. The compounds made no changes in RORγt, nestin, Gas6, Tyro3, and Mertk mRNA expression levels in the spinal cord. The study revealed that both TEH and ART can effectively modulate the genes responsible for inflammation and myelination that play a crucial role in EAE. Interestingly, TEH demonstrated a greater potency compared to ART and hence may have the potential to be evaluated in interventions for the management of MS.