Targeting SRSF2 mutations in leukemia with RKI-1447: A strategy to impair cellular division and nuclear structure

Spliceosome machinery mutations are common early mutations in myeloid malignancies; however, effective targeted therapies against them are still lacking. In the current study, we used an in vitro high-throughput drug screen among four different isogenic cell lines and identified RKI-1447, a Rho-associated protein kinase inhibitor, as selective cytotoxic effector of SRSF2 mutant cells. RKI-1447 targeted SRSF2 mutated primary human samples in xenografts models. RKI-1447 induced mitotic catastrophe and induced major reorganization of the microtubule system and severe nuclear deformation. Transmission electron microscopy and 3D light microscopy revealed that SRSF2 mutations induce deep nuclear indentation and segmentation that are apparently driven by microtubule-rich cytoplasmic intrusions, which are exacerbated by RKI-1447. The severe nuclear deformation in RKI-1447-treated SRSF2 mutant cells prevents cells from completing mitosis. These findings shed new light on the interplay between microtubules and the nucleus and offers new ways for targeting pre-leukemic SRSF2 mutant cells.

Age-related micro-environmental changes as drivers of clonal hematopoiesis

PURPOSE OF REVIEW

Both aging and reduced diversity at the hematopoietic stem cells (HSCs) level are ubiquitous. What remains unclear is why some individuals develop clonal hematopoiesis (CH), and why does CH due to specific mutations occur in specific individuals. Much like aging, reduced diversity of HSCs is a complex phenotype shaped by numerous factors (germline & environment). The purpose of the current review is to discuss the role of two other age-related ubiquitous processes that might contribute to the dynamics and characteristics of losing HSC diversity and the evolution of CH. These processes have not been reviewed in depth so far and include the accumulation of fatty bone marrow (FBM), and the decline in sex hormones.

RECENT FINDINGS

Interestingly, sex hormone decline can directly shape HSC function, but also reshape the delicate balance of BM supporting cells, with a shift towards FBM. FBM accumulation can shape the clonal expansion of preleukemic mutations, particularly DNMT3A mutations, through IL-6 mediation. DNMT3A mutations are one of the only preleukemic mutations which is more prevalent in women, and especially in women with early menopause, demonstrating an association between age-related hormone decline and CH evolution, the mechanisms of which are yet to be discovered.

SUMMARY

Aging is a multifactorial phenotype and the same is true for the aging of the blood system. While many factors which can shape CH have been discussed, we shed more light on FBM and sex hormone decline. Much more is missing: how and should we even try to prevent these phenomena? Why do they occur? and how they are connected to other age-related blood factors?

Inflammatory signals from fatty bone marrow support DNMT3A driven clonal hematopoiesis

Both fatty bone marrow (FBM) and somatic mutations in hematopoietic stem cells (HSCs), also termed clonal hematopoiesis (CH) accumulate with human aging. However it remains unclear whether FBM can modify the evolution of CH. To address this question, we herein present the interaction between CH and FBM in two preclinical male mouse models: after sub-lethal irradiation or after castration. An adipogenesis inhibitor (PPARγ inhibitor) is used in both models as a control. A significant increase in self-renewal can be detected in both human and rodent DNMT3A^Mut-HSCs when exposed to FBM. DNMT3A^Mut-HSCs derived from older mice interacting with FBM have even higher self-renewal in comparison to DNMT3A^Mut-HSCs derived from younger mice. Single cell RNA-sequencing on rodent HSCs after exposing them to FBM reveal a 6-10 fold increase in DNMT3A^Mut-HSCs and an activated inflammatory signaling. Cytokine analysis of BM fluid and BM derived adipocytes grown in vitro demonstrates an increased IL-6 levels under FBM conditions. Anti-IL-6 neutralizing antibodies significantly reduce the selective advantage of DNMT3A^Mut-HSCs exposed to FBM. Overall, paracrine FBM inflammatory signals promote DNMT3A-driven clonal hematopoiesis, which can be inhibited by blocking the IL-6 pathway.

The role of RNF149 in the pre-emptive quality control substrate ubiquitination

Protein quality control is a process in which a protein's folding status is constantly monitored. Mislocalized proteins (MLP), are processed by the various quality control pathways, as they are often misfolded due to inappropriate cellular surroundings. Polypeptides that fail to translocate into the ER due to an inefficient signal peptide, mutations or ER stress are recognized by the pre-emptive ER associated quality control (pEQC) pathway and degraded by the 26 S proteasome. In this report we reveal the role of RNF149, a membrane bound E3 ligase in the ubiquitination of known pEQC substrates. We demonstrate its selective binding only to non-translocated proteins and its association with known pEQC components. Impairment in RNF149 function increases translocation flux into the ER and manifests in a myeloproliferative neoplasm (MPN) phenotype, a pathological condition associated with pEQC impairment. Finally, the dynamic localization of RNF149 may provide a molecular switch to regulate pEQC during ER stress.

Clonal hematopoiesis in the donor does not adversely affect long-term outcomes following allogeneic hematopoietic stem cell transplantation: result from 13-year followup

Donor clonal hematopoiesis may be transferred to the recipient through allogeneic hematopoietic stem cell transplantation (HCT), but the potential for adverse long-term impact on transplant outcomes remains unknown. A total of 744 samples from 372 recipients who received HCT and the corresponding donors were included. Bar-coded error-corrected sequencing using a modified molecular inversion probe capture protocol was performed, which targeted 34 genes covering mutations involved in clonal hematopoiesis with indeterminate potential (CHIP) and other AML-related mutations. A total of 30 mutations were detected from 25 donors (6.7%): the most frequently mutated gene was TET2 (n=7, 28%), followed by DNMT3A (n=4, 16%), SMC3 (n=3, 12%) and SF3B1 (n=3, 12%). With a median follow-up duration of 13 years among survivors, the presence of CHIP in the donor was not associated with recipient overall survival (p=0.969), relapse incidence (p=0.600) or non-relapse mortality (p=0.570). Donor CHIP did not impair neutrophil (p=0.460) or platelet (p=0.250) engraftment, the rates of acute (p=0.490), or chronic graft-vs-host disease (p=0.220). No significant difference was noted for secondary malignancy following HCT between the two groups. The present study suggests that the presence of CHIP in allogeneic stem donors does not adversely affect transplant outcomes after HCT. Accordingly, further study is warranted to reach a clearer conclusion on whether molecular profiling to determine the presence of CHIP mutations is necessary for the pre-transplant evaluation of donors prior to stem cell donation.

Pseudo-mutant P53 is a unique phenotype of DNMT3A-mutated pre-leukemia

Pre-leukemic clones carrying DNMT3A mutations have a selective advantage and an inherent chemoresistance, however the basis for this phenotype has not been fully elucidated. Mutations affecting the gene TP53 occur in pre-leukemic hema-topoietic stem/progenitor cells (preL-HSPC) and lead to chemoresistance. Many of these mutations cause a conformational change and some of them were shown to enhance self-renewal capacity of preL-HSPC. Intriguingly, a misfolded P53 was described in AML blasts that do not harbor mutations in TP53, emphasizing the dynamic equilibrium between wild-type (WT) and “pseudo-mutant” conformations of P53. By combining single cell analyses and P53 conformation-specific monoclonal antibodies we studied preL-HSPC from primary human DNMT3A-mutated AML samples. We found that while leu-kemic blasts express mainly the WT conformation, in preL-HSPC the pseudo-mutant conformation is the dominant. HSPC from non-leukemic samples expressed both conformations to a similar extent. In a mouse model we found a small subset of HSPC with a dominant pseudo-mutant P53. This subpopulation was significantly larger among DNMT3A^R882H-mutated HSPC, suggesting that while a pre-leukemic mutation can predispose for P53 misfolding, additional factors are involved as well. Treatment with a short peptide that can shift the dynamic equilibrium favoring the WT conformation of P53, specifically eliminated preL-HSPC that had dysfunctional canonical P53 pathway activity as reflected by single cell RNA sequencing. Our observations shed light upon a possible targetable P53 dysfunction in human preL-HSPC carrying DNMT3A mutations. This opens new avenues for leukemia prevention.

An improved molecular inversion probe based targeted sequencing approach for low variant allele frequency

Deep targeted sequencing technologies are still not widely used in clinical practice due to the complexity of the methods and their cost. The Molecular Inversion Probes (MIP) technology is cost effective and scalable in the number of targets, however, suffers from low overall performance especially in GC rich regions. In order to improve the MIP performance, we sequenced a large cohort of healthy individuals (n = 4417), with a panel of 616 MIPs, at high depth in duplicates. To improve the previous state-of-the-art statistical model for low variant allele frequency, we selected 4635 potentially positive variants and validated them using amplicon sequencing. Using machine learning prediction tools, we significantly improved precision of 10–56.25% (P < 0.0004) to detect variants with VAF > 0.005. We further developed biochemically modified MIP protocol and improved its turn-around-time to ∼4 h. Our new biochemistry significantly improved uniformity, GC-Rich regions coverage, and enabled 95% on target reads in a large MIP panel of 8349 genomic targets. Overall, we demonstrate an enhancement of the MIP targeted sequencing approach in both detection of low frequency variants and in other key parameters, paving its way to become an ultrafast cost-effective research and clinical diagnostic tool.

Recurrent deletions in clonal hematopoiesis are driven by microhomology-mediated end joining

The mutational mechanisms underlying recurrent deletions in clonal hematopoiesis are not entirely clear. In the current study we inspect the genomic regions around recurrent deletions in myeloid malignancies, and identify microhomology-based signatures in CALR, ASXL1 and SRSF2 loci. We demonstrate that these deletions are the result of double stand break repair by a PARP1 dependent microhomology-mediated end joining (MMEJ) pathway. Importantly, we provide evidence that these recurrent deletions originate in pre-leukemic stem cells. While DNA polymerase theta (POLQ) is considered a key component in MMEJ repair, we provide evidence that pre-leukemic MMEJ (preL-MMEJ) deletions can be generated in POLQ knockout cells. In contrast, aphidicolin (an inhibitor of replicative polymerases and replication) treatment resulted in a significant reduction in preL-MMEJ. Altogether, our data indicate an association between POLQ independent MMEJ and clonal hematopoiesis and elucidate mutational mechanisms involved in the very first steps of leukemia evolution.

Dasatinib response in acute myeloid leukemia is correlated with FLT3/ITD, PTPN11 mutations and a unique gene expression signature

Novel targeted therapies demonstrate improved survival in specific subgroups (defined by genetic variants) of acute myeloid leukemia (AML) patients, validating the paradigm of molecularly targeted therapy. However, identifying correlations between AML molecular attributes and effective therapies is challenging. Recent advances in high-throughput in vitro drug sensitivity screening applied to primary AML blasts were used to uncover such correlations; however, these methods cannot predict the response of leukemic stem cells (LSCs). Our study aimed to predict in vitro response to targeted therapies, based on molecular markers, with subsequent validation in LSCs. We performed ex vivo sensitivity screening to 46 drugs on 29 primary AML samples at diagnosis or relapse. Using unsupervised hierarchical clustering analysis we identified group with sensitivity to several tyrosine kinase inhibitors (TKIs), including the multi-TKI, dasatinib, and searched for correlations between dasatinib response, exome sequencing and gene expression from our dataset and from the Beat AML dataset. Unsupervised hierarchical clustering analysis of gene expression resulted in clustering of dasatinib responders and non-responders. In vitro response to dasatinib could be predicted based on gene expression (AUC=0.78). Furthermore, mutations in FLT3/ITD and PTPN11 were enriched in the dasatinib sensitive samples as opposed to mutations in TP53 which were enriched in resistant samples. Based on these results, we selected FLT3/ITD AML samples and injected them to NSG-SGM3 mice. Our results demonstrate that in a subgroup of FLT3/ITD AML (4 out of 9) dasatinib significantly inhibits LSC engraftment. In summary we show that dasatinib has an anti-leukemic effect both on bulk blasts and, more importantly, LSCs from a subset of AML patients that can be identified based on mutational and expression profiles. Our data provide a rational basis for clinical trials of dasatinib in a molecularly selected subset of AML patients.

The Median Eminence, A New Oligodendrogenic Niche in the Adult Mouse Brain

The subventricular zone (SVZ) of the lateral ventricles and the subgranular zone (SGZ) of the dentate gyrus in the hippocampus are known as neurogenic niches. We show that the median eminence (ME) of the hypothalamus comprises BrdU+ newly proliferating cells co-expressing NG2 (oligodendrocyte progenitors) and RIP (pre-myelinating oligodendrocytes), suggesting their differentiation toward mature oligodendrocytes (OLs). ME cells can generate neurospheres (NS) in vitro, which differentiate mostly to OLs compared with SVZ-NS that typically generate neurons. Interestingly, this population of oligodendrocyte progenitors is increased in the ME from experimental autoimmune encephalomyelitis (EAE)-affected mice. Notably, the thrombospondin 1 (TSP1) expressed by astrocytes, acts as negative regulator of oligodendrogenesis in vitro and is downregulated in the ME of EAE mice. Importantly, transplanted ME-NS preferentially differentiate to MBP+ OLs compared with SVZ-NS in Shiverer mice. Hence, discovering the ME as a new site for myelin-producing cells has a great importance for advising future therapy for demyelinating diseases and spinal cord injury.

Circulating Picomolar Levels of CCL2 Downregulate Ongoing Chronic Experimental Autoimmune Encephalomyelitis by Induction of Regulatory Mechanisms

Multiple sclerosis is an inflammatory disease of the CNS characterized by neurologic impairment resulting from primary demyelination and axonal damage. The pathogenic mechanisms of disease development include Ag-specific T cell activation and Th1 differentiation, followed by T cell and macrophage migration into the CNS. CCL2 is a chemokine that induces migration of monocytes, memory T cells, and dendritic cells. We previously demonstrated that picomolar levels of CCL2 strongly restrict the development of inflammation in models of inflammatory bowel disease. Moreover, CCR2 deficiency in T cells promotes a program inducing the accumulation of Foxp3⁺ regulatory T cells while decreasing the levels of Th17 cells in vivo. In the current study, the effect of picomolar levels of CCL2 on the autoimmune inflammatory response associated with a multiple sclerosis-like disease in mice was analyzed. We found that low dosages of CCL2 were effective in suppressing MOG-induced experimental autoimmune encephalomyelitis (EAE), and they downregulated chronic EAE. The modulation of EAE by CCL2 was associated with downregulation of Th1/Th17 cells and upregulation of TGF-β and induction of regulatory CD4⁺Foxp3 T cells. Most strikingly, these low levels of CCL2 induced formation of highly functional regulatory T cells. Thus, this study strongly supports the potential use of CCL2 as a regulatory mediator for treating inflammatory autoimmune diseases.

Modulation of MS-like disease by a multi epitope protein is mediated by induction of CD11c+CD11b+Gr1+ myeloid-derived dendritic cells

Specific neutralization of the pathogenic autoimmune cells is the ultimate goal in therapy of Multiple Sclerosis (MS). However, the pathogenic autoimmunity in MS, can be directed against several major target antigens, and therefore targeting pathogenic T-cells directed against a single target antigen is unlikely to be effective. To overcome this multiplicity and the potential complexity of pathogenic autoreactivities in MS, we have put forward the concept of concomitant multi-antigen/multi-epitope targeting as, a conceivably more effective approach to immunotherapy of MS. We constructed an (Experimental Autoimmune Encephalomeylitis (EAE)/MS-related synthetic human Target Autoantigen Gene (MS-shMultiTAG) designed to encode in tandem only EAE/MS related epitopes of all known encephalitogenic proteins. The MS-related protein product (designated Y-MSPc) was immunofunctional and upon tolerogenic administration, it effectively suppressed and reversed EAE induced by a single encephalitogenic protein. Furthermore, Y-MSPc also fully abrogated the development of "complex EAE" induced by a mixture of five encephalitogenic T-cell lines, each specific for a different encephalitogenic epitope of MBP, MOG, PLP, MOBP and OSP. Strikingly, Y-MSPc was consistently more effective than treatment with the single disease-specific peptide or with the peptide cocktail, both in suppressing the development of "classical" or "complex" EAE and in ameliorating ongoing disease. Overall, the modulation of EAE by Y-MSPc was associated with anergizing the pathogenic autoreactive T-cells, downregulation of Th1/Th17 cytokine secretion and upregulation of TGF-β secretion. Moreover, we show that both suppression and treatment of ongoing EAE by tolerogenic administration of Y-MSPc is associated also with a remarkable increase in a unique subset of dendritic-cells (DCs), CD11c+CD11b+Gr1+-myeloid derived DCs in both spleen and CNS of treated mice. These DCs, which are with strong immunoregulatory characteristics and are functional in down-modulation of MS-like-disease displayed increased production of IL-4, IL-10 and TGF-β and low IL-12. Functionally, these myeloid DCs suppress the in-vitro proliferation of myelin-specific T-cells and more importantly, the cells were functional in-vivo, as their adoptive transfer into EAE induced mice resulted in strong suppression of the disease, associated with a remarkable induction of CD4 + FoxP3+ regulatory cells. These results, which highlight the efficacy of "multi-epitope-targeting" agent in induction of functional regulatory CD11c+CD11b+Gr1+myeloid DCs, further indicate the potential role of these DCs in maintaining peripheral tolerance and their involvement in downregulation of MS-like-disease.

Daily Onset of Light and Darkness Differentially Controls Hematopoietic Stem Cell Differentiation and Maintenance

Hematopoietic stem and progenitor cells (HSPCs) tightly couple maintenance of the bone marrow (BM) reservoir, including undifferentiated long-term repopulating hematopoietic stem cells (LT-HSCs), with intensive daily production of mature leukocytes and blood replenishment. We found two daily peaks of BM HSPC activity that are initiated by onset of light and darkness providing this coupling. Both peaks follow transient elevation of BM norepinephrine and TNF secretion, which temporarily increase HSPC reactive oxygen species (ROS) levels. Light-induced norepinephrine and TNF secretion augments HSPC differentiation and increases vascular permeability to replenish the blood. In contrast, darkness-induced TNF increases melatonin secretion to drive renewal of HSPCs and LT-HSC potential through modulating surface CD150 and c-Kit expression, increasing COX-2/αSMA+ macrophages, diminishing vascular permeability, and reducing HSPC ROS levels. These findings reveal that light- and darkness-induced daily bursts of norepinephrine, TNF, and melatonin within the BM are essential for synchronized mature blood cell production and HSPC pool repopulation.

Small Molecules Co-targeting CKIα and the Transcriptional Kinases CDK7/9 Control AML in Preclinical Models

CKIα ablation induces p53 activation, and CKIα degradation underlies the therapeutic effect of lenalidomide in a pre-leukemia syndrome. Here we describe the development of CKIα inhibitors, which co-target the transcriptional kinases CDK7 and CDK9, thereby augmenting CKIα-induced p53 activation and its anti-leukemic activity. Oncogene-driving super-enhancers (SEs) are highly sensitive to CDK7/9 inhibition. We identified multiple newly gained SEs in primary mouse acute myeloid leukemia (AML) cells and demonstrate that the inhibitors abolish many SEs and preferentially suppress the transcription elongation of SE-driven oncogenes. We show that blocking CKIα together with CDK7 and/or CDK9 synergistically stabilize p53, deprive leukemia cells of survival and proliferation-maintaining SE-driven oncogenes, and induce apoptosis. Leukemia progenitors are selectively eliminated by the inhibitors, explaining their therapeutic efficacy with preserved hematopoiesis and leukemia cure potential; they eradicate leukemia in MLL-AF9 and Tet2^-/-;Flt3^ITD AML mouse models and in several patient-derived AML xenograft models, supporting their potential efficacy in curing human leukemia.

Inhomogeneous Encoding of the Visual Field in the Mouse Retina

Stimulus characteristics of the mouse's visual field differ above and below the skyline. Here, we show for the first time that retinal ganglion cells (RGCs), the output neurons of the retina, gradually change their functional properties along the ventral-dorsal axis to allow better representation of the different stimulus characteristics. We conducted two-photon targeted recordings of transient-Offα-RGCs and found that they gradually became more sustained along the ventral-dorsal axis, revealing >5-fold-longer duration responses in the dorsal retina. Using voltage-clamp recordings, pharmacology, and genetic manipulation, we demonstrated that the primary rod pathway underlies this variance. Our findings challenge the current belief that RGCs of the same subtype exhibit the same light responses, regardless of retinal location, and suggest that networks underlying RGC responses may change with retinal location to enable optimized sampling of the visual image.

CCR2 Regulates the Immune Response by Modulating the Interconversion and Function of Effector and Regulatory T Cells

Chemokines and chemokine receptors establish a complex network modulating immune cell migration and localization. These molecules were also suggested to mediate the differentiation of leukocytes; however, their intrinsic, direct regulation of lymphocyte fate remained unclear. CCR2 is the main chemokine receptor inducing macrophage and monocyte recruitment to sites of inflammation, and it is also expressed on T cells. To assess whether CCR2 directly regulates T cell responses, we followed the fates of CCR2^-/- T cells in T cell-specific inflammatory models. Our in vitro and in vivo results show that CCR2 intrinsically mediates the expression of inflammatory T cell cytokines, and its absence on T cells results in attenuated colitis progression. Moreover, CCR2 deficiency in T cells promoted a program inducing the accumulation of Foxp3⁺ regulatory T cells, while decreasing the levels of Th17 cells in vivo, indicating that CCR2 regulates the immune response by modulating the effector/regulatory T ratio.

Anti-inflammatory effects of the cannabidiol derivative dimethylheptyl-cannabidiol - studies in BV-2 microglia and encephalitogenic T cells

BACKGROUND

Dimethylheptyl-cannabidiol (DMH-CBD), a non-psychoactive, synthetic derivative of the phytocannabinoid cannabidiol (CBD), has been reported to be anti-inflammatory in RAW macrophages. Here, we evaluated the effects of DMH-CBD at the transcriptional level in BV-2 microglial cells as well as on the proliferation of encephalitogenic T cells.

METHODS

BV-2 cells were pretreated with DMH-CBD, followed by stimulation with the endotoxin lipopolysaccharide (LPS). The expression levels of selected genes involved in stress regulation and inflammation were determined by quantitative real-time PCR. In addition, MOG35-55-reactive T cells (TMOG) were cultured with antigen-presenting cells in the presence of DMH-CBD and MOG35-55 peptide, and cell proliferation was determined by measuring [3H]thymidine incorporation.

RESULTS

DMH-CBD treatment downregulated in a dose-dependent manner the mRNA expression of LPS-upregulated pro-inflammatory genes (Il1b, Il6, and Tnf) in BV-2 microglial cells. The expression of these genes was also downregulated by DMH-CBD in unstimulated cells. In parallel, DMH-CBD upregulated the expression of genes related to oxidative stress and glutathione homeostasis such as Trb3, Slc7a11/xCT, Hmox1, Atf4, Chop, and p8 in both stimulated and unstimulated microglial cells. In addition, DMH-CBD dose-dependently inhibited MOG35-55-induced TMOG proliferation.

CONCLUSIONS

The results show that DMH-CBD has similar anti-inflammatory properties to those of CBD. DMH-CBD downregulates the expression of inflammatory cytokines and protects the microglial cells by inducing an adaptive cellular response against inflammatory stimuli and oxidative injury. In addition, DMH-CBD decreases the proliferation of pathogenic activated TMOG cells.

Pathways and gene networks mediating the regulatory effects of cannabidiol, a nonpsychoactive cannabinoid, in autoimmune T cells

Background

Our previous studies showed that the non-psychoactive cannabinoid, cannabidiol (CBD), ameliorates the clinical symptoms in mouse myelin oligodendrocyte glycoprotein (MOG)35-55-induced experimental autoimmune encephalomyelitis model of multiple sclerosis (MS) as well as decreases the memory MOG35-55-specific T cell (T_MOG) proliferation and cytokine secretion including IL-17, a key autoimmune factor. The mechanisms of these activities are currently poorly understood.

Methods

Herein, using microarray-based gene expression profiling, we describe gene networks and intracellular pathways involved in CBD-induced suppression of these activated memory T_MOG cells. Encephalitogenic T_MOG cells were stimulated with MOG35-55 in the presence of spleen-derived antigen presenting cells (APC) with or without CBD. mRNA of purified T_MOG was then subjected to Illumina microarray analysis followed by ingenuity pathway analysis (IPA), weighted gene co-expression network analysis (WGCNA) and gene ontology (GO) elucidation of gene interactions. Results were validated using qPCR and ELISA assays.

Results

Gene profiling showed that the CBD treatment suppresses the transcription of a large number of proinflammatory genes in activated T_MOG. These include cytokines (Xcl1, Il3, Il12a, Il1b), cytokine receptors (Cxcr1, Ifngr1), transcription factors (Ier3, Atf3, Nr4a3, Crem), and TNF superfamily signaling molecules (Tnfsf11, Tnfsf14, Tnfrsf9, Tnfrsf18). “IL-17 differentiation” and “IL-6 and IL-10-signaling” were identified among the top processes affected by CBD. CBD increases a number of IFN-dependent transcripts (Rgs16, Mx2, Rsad2, Irf4, Ifit2, Ephx1, Ets2) known to execute anti-proliferative activities in T cells. Interestingly, certain MOG35-55 up-regulated transcripts were maintained at high levels in the presence of CBD, including transcription factors (Egr2, Egr1, Tbx21), cytokines (Csf2, Tnf, Ifng), and chemokines (Ccl3, Ccl4, Cxcl10) suggesting that CBD may promote exhaustion of memory T_MOG cells. In addition, CBD enhanced the transcription of T cell co-inhibitory molecules (Btla, Lag3, Trat1, and CD69) known to interfere with T/APC interactions. Furthermore, CBD enhanced the transcription of oxidative stress modulators with potent anti-inflammatory activity that are controlled by Nfe2l2/Nrf2 (Mt1, Mt2a, Slc30a1, Hmox1).

Conclusions

Microarray-based gene expression profiling demonstrated that CBD exerts its immunoregulatory effects in activated memory T_MOG cells via (a) suppressing proinflammatory Th17-related transcription, (b) by promoting T cell exhaustion/tolerance, (c) enhancing IFN-dependent anti-proliferative program, (d) hampering antigen presentation, and (d) inducing antioxidant milieu resolving inflammation. These findings put forward mechanism by which CBD exerts its anti-inflammatory effects as well as explain the beneficial role of CBD in pathological memory T cells and in autoimmune diseases.

Electronic supplementary material

The online version of this article (doi:10.1186/s12974-016-0603-x) contains supplementary material, which is available to authorized users.

Post-CNS-inflammation expression of CXCL12 promotes the endogenous myelin/neuronal repair capacity following spontaneous recovery from multiple sclerosis-like disease

BACKGROUND

Demyelination and axonal degeneration, hallmarks of multiple sclerosis (MS), are associated with the central nervous system (CNS) inflammation facilitated by C-X-C motif chemokine 12 (CXCL12) chemokine. Both in MS and in experimental autoimmune encephalomyelitis (EAE), the deleterious CNS inflammation has been associated with upregulation of CXCL12 expression in the CNS. We investigated the expression dynamics of CXCL12 in the CNS with progression of clinical EAE and following spontaneous recovery, with a focus on CXCL12 expression in the hippocampal neurogenic dentate gyrus (DG) and in the corpus callosum (CC) of spontaneously recovered mice, and its potential role in promoting the endogenous myelin/neuronal repair capacity.

METHODS

CNS tissue sections from mice with different clinical EAE phases or following spontaneous recovery and in vitro differentiated adult neural stem cell cultures were analyzed by immunofluorescent staining and confocal imaging for detecting and enumerating neuronal progenitor cells (NPCs) and oligodendrocyte precursor cells (OPCs) and for expression of CXCL12.

RESULTS

Our expression dynamics analysis of CXCL12 in the CNS with EAE progression revealed elevated CXCL12 expression in the DG and CC, which persistently increases following spontaneous recovery even though CNS inflammation has subsided. Correspondingly, the numbers of NPCs and OPCs in the DG and CC, respectively, of EAE-recovered mice increased compared to that of naïve mice (NPCs, p < 0.0001; OPCs, p < 0.00001) or mice with active disease (OPCs, p < 0.0005). Notably, about 30 % of the NPCs and unexpectedly also OPCs (~50 %) express CXCL12, and their numbers in DG and CC, respectively, are higher in EAE-recovered mice compared with naïve mice and also compared with mice with ongoing clinical EAE (CXCL12(+) NPCs, p < 0.005; CXCL12(+) OPCs, p < 0.0005). Moreover, a significant proportion (>20 %) of the CXCL12(+) NPCs and OPCs co-express the CXCL12 receptor, CXCR4, and their numbers significantly increase with recovery from EAE not only relative to naïve mice (p < 0.0002) but also to mice with ongoing EAE (p < 0.004).

CONCLUSIONS

These data link CXCL12 expression in the DG and CC of EAE-recovering mice to the promotion of neuro/oligodendrogenesis generating CXCR4(+) CXCL12(+) neuronal and oligodendrocyte progenitor cells endowed with intrinsic neuro/oligondendroglial differentiation potential. These findings highlight the post-CNS-inflammation role of CXCL12 in augmenting the endogenous myelin/neuronal repair capacity in MS-like disease, likely via CXCL12/CXCR4 autocrine signaling.

HU-446 and HU-465, Derivatives of the Non-psychoactive Cannabinoid Cannabidiol, Decrease the Activation of Encephalitogenic T Cells

Cannabidiol (CBD), the non-psychoactive cannabinoid, has been previously shown by us to decrease peripheral inflammation and neuroinflammation in mouse experimental autoimmune encephalomyelitis (EAE) model of multiple sclerosis (MS). Here we have studied the anti-inflammatory effects of newly synthesized derivatives of natural (-)-CBD ((-)-8,9-dihydro-7-hydroxy-CBD; HU-446) and of synthetic (+)-CBD ((+)-8,9-dihydro-7-hydroxy-CBD; HU-465) on activated myelin oligodendrocyte glycoprotein (MOG)35-55-specific mouse encephalitogenic T cells (T(MOG) ) driving EAE/MS-like pathologies. Binding assays followed by molecular modeling revealed that HU-446 has negligible affinity toward the cannabinoid CB1 and CB2 receptors while HU-465 binds to both CB1 and CB2 receptors at the high nanomolar concentrations (Ki = 76.7 ± 5.8 nm and 12.1 ± 2.3 nm, respectively). Both, HU-446 and HU-465, at 5 and 10 μm (but not at 0.1 and 1 μm), inhibited the MOG35-55-induced proliferation of autoreactive T(MOG) cells via CB1/CB2 receptor independent mechanisms. Moreover, both HU-446 and HU-465, at 5 and 10 μm, inhibited the release of IL-17, a key autoimmune cytokine, from MOG35-55-stimulated T(MOG) cells. These results suggest that HU-446 and HU-465 have anti-inflammatory potential in inflammatory and autoimmune diseases.

Role of a Novel Human Leukocyte Antigen-DQA1*01:02;DRB1*15:01 Mixed Isotype Heterodimer in the Pathogenesis of "Humanized" Multiple Sclerosis-like Disease

Gene-wide association and candidate gene studies indicate that the greatest effect on multiple sclerosis (MS) risk is driven by the HLA-DRB1*15:01 allele within the HLA-DR15 haplotype (HLA-DRB1*15:01-DQA1*01:02-DQB1*0602-DRB5*01:01). Nevertheless, linkage disequilibrium makes it difficult to define, without functional studies, whether the functionally relevant effect derives from DRB1*15:01 only, from its neighboring DQA1*01:02-DQB1*06:02 or DRB5*01:01 genes of HLA-DR15 haplotype, or from their combinations or epistatic interactions. Here, we analyzed the impact of the different HLA-DR15 haplotype alleles on disease susceptibility in a new "humanized" model of MS induced in HLA-transgenic (Tg) mice by human oligodendrocyte-specific protein (OSP)/claudin-11 (hOSP), one of the bona fide potential primary target antigens in MS. We show that the hOSP-associated MS-like disease is dominated by the DRB1*15:01 allele not only as the DRA1*01:01;DRB1*15:01 isotypic heterodimer but also, unexpectedly, as a functional DQA1*01:02;DRB1*15:01 mixed isotype heterodimer. The contribution of HLA-DQA1/DRB1 mixed isotype heterodimer to OSP pathogenesis was revealed in (DRB1*1501xDQB1*0602)F1 double-Tg mice immunized with hOSP(142-161) peptide, where the encephalitogenic potential of prevalent DRB1*1501/hOSP(142-161)-reactive Th1/Th17 cells is hindered due to a single amino acid difference in the OSP(142-161) region between humans and mice; this impedes binding of DRB1*1501 to the mouse OSP(142-161) epitope in the mouse CNS while exposing functional binding of mouse OSP(142-161) to DQA1*01:02;DRB1*15:01 mixed isotype heterodimer. This study, which shows for the first time a functional HLA-DQA1/DRB1 mixed isotype heterodimer and its potential association with disease susceptibility, provides a rationale for a potential effect on MS risk from DQA1*01:02 through functional DQA1*01:02;DRB1*15:01 antigen presentation. Furthermore, it highlights a potential contribution to MS risk also from interisotypic combination between products of neighboring HLA-DR15 haplotype alleles, in this case the DQA1/DRB1 combination.

Cannabidiol, a non-psychoactive cannabinoid, leads to EGR2-dependent anergy in activated encephalitogenic T cells

Background

Cannabidiol (CBD), the main non-psychoactive cannabinoid, has been previously shown by us to ameliorate clinical symptoms and to decrease inflammation in myelin oligodendrocyte glycoprotein (MOG)35-55-induced mouse experimental autoimmune encephalomyelitis model of multiple sclerosis as well as to decrease MOG35-55-induced T cell proliferation and IL-17 secretion. However, the mechanisms of CBD anti-inflammatory activities are unclear.

Methods

Here we analyzed the effects of CBD on splenocytes (source of accessory T cells and antigen presenting cells (APC)) co-cultured with MOG35-55-specific T cells (T_MOG) and stimulated with MOG35-55. Using flow cytometry, we evaluated the expression of surface activation markers and inhibitory molecules on T cells and B cells. T_MOG cells were purified using CD4 positive microbead selection and submitted for quantitative PCR and microarray of mRNA transcript analyzes. Cell signaling studies in purified T_MOG were carried out using immunoblotting.

Results

We found that CBD leads to upregulation of CD69 and lymphocyte-activation gene 3 (LAG3) regulatory molecules on CD4⁺CD25⁻ accessory T cells. This subtype of CD4⁺CD25⁻CD69⁺LAG3⁺ T cells has been recognized as induced regulatory phenotype promoting anergy in activated T cells. Indeed, we observed that CBD treatment results in upregulation of EGR2 (a key T cell anergy inducer) mRNA transcription in stimulated T_MOG cells. This was accompanied by elevated levels of anergy promoting genes such as IL-10 (anti-inflammatory cytokine), STAT5 (regulatory factor), and LAG3 mRNAs, as well as of several enhancers of cell cycle arrest (such as Nfatc1, Casp4, Cdkn1a, and Icos). Moreover, CBD exposure leads to a decrease in STAT3 and to an increase in STAT5 phosphorylation in T_MOG cells, positive and negative regulators of Th17 activity, respectively. In parallel, we observed decreased levels of major histocompatibility complex class II (MHCII), CD25, and CD69 on CD19⁺ B cells following CBD treatment, showing diminished antigen presenting capabilities of B cells and reduction in their pro-inflammatory functions.

Conclusions

Our data suggests that CBD exerts its immunoregulatory effects via induction of CD4⁺CD25⁻CD69⁺LAG3⁺ cells in MOG35-55-activated APC/T_MOG co-cultures. This is accompanied by EGR2-dependent anergy of stimulated T_MOG cells as well as a switch in their intracellular STAT3/STAT5 activation balance leading to the previously observed decrease in Th17 activity.

DQB1*06:02-Associated Pathogenic Anti-Myelin Autoimmunity in Multiple Sclerosis-Like Disease: Potential Function of DQB1*06:02 as a Disease-Predisposing Allele

Susceptibility to multiple sclerosis (MS) has been linked mainly to the HLA-DRB1 locus, with the HLA-DR15 haplotype (DRB1*1501-DQA1*0102-DQB1*0602-DRB5*0101) dominating MS risk in Caucasians. Although genes in the HLA-II region, particularly DRB1*1501, DQA1*0102-DQB1*0602, are in tight linkage disequilibrium, genome-wide-association, and gene candidate studies identified the DRB1*15:01 allele as the primary risk factor in MS. Many genetic and immune-functional studies have indicated DRB1*15:01 as a primary risk factor in MS, while only some functional studies suggested a disease-modifying role for the DRB5*01 or DQB1*06 alleles. In this respect, the susceptibility of DRB1*15:01-transgenic (Tg) mice to myelin basic protein- or myelin oligodendrocyte glycoprotein-induced MS-like disease is consistent with primary contribution of DRB1*15:01 to HLA-DR15+ MS. The studies summarized here show that susceptibility to MS-like disease, induced in HLA-“humanized” mice by myelin oligodendrocytic basic protein or by the proteolipid protein, one of the most prominent encephalitogenic target antigens implicated in human MS, is determined by DQB1*06:02, rather than by the DRB1*15:01 allele. These findings not only offer a rationale for a potential role for DQB1*06:02 in predisposing susceptibility to MS, but also suggest a more complex and differential functional role for HLA-DR15 alleles, depending on the primary target myelin antigen. However, the conflict between these findings in HLA-Tg mice and the extensive genome-wide-association studies, which could not detect any significant effect from the DQB1*06:02 allele on MS risk, is rather puzzling. Functional analysis of MS PBLs for DQB1*06:02-associated anti-myelin autoimmunity may indicate whether or not DQB1*06:02 is associated with MS pathogenesis.

From classic to spontaneous and humanized models of multiple sclerosis: impact on understanding pathogenesis and drug development

Multiple sclerosis (MS), a demyelinating disease of the central nervous system (CNS), presents as a complex disease with variable clinical and pathological manifestations, involving different pathogenic pathways. Animal models, particularly experimental autoimmune encephalomyelitis (EAE), have been key to deciphering the pathophysiology of MS, although no single model can recapitulate the complexity and diversity of MS, or can, to date, integrate the diverse pathogenic pathways. Since the first EAE model was introduced decades ago, multiple classic (induced), spontaneous, and humanized EAE models have been developed, each recapitulating particular aspects of MS pathogenesis. The advances in technologies of genetic ablation and transgenesis in mice of C57BL/6J background and the development of myelin-oligodendrocyte glycoprotein (MOG)-induced EAE in C57BL/6J mice yielded several spontaneous and humanized EAE models, and resulted in a plethora of EAE models in which the role of specific genes or cell populations could be precisely interrogated, towards modeling specific pathways of MS pathogenesis/regulation in MS. Collectively, the numerous studies on the different EAE models contributed immensely to our basic understanding of cellular and molecular pathways in MS pathogenesis as well as to the development of therapeutic agents: several drugs available today as disease modifying treatments were developed from direct studies on EAE models, and many others were tested or validated in EAE. In this review, we discuss the contribution of major classic, spontaneous, and humanized EAE models to our understanding of MS pathophysiology and to insights leading to devising current and future therapies for this disease.

An immunomodulating motif of the HIV-1 fusion protein is chirality-independent: implications for its mode of action

An immunosuppressive motif was recently found within the HIV-1 gp41 fusion protein (termed immunosuppressive loop-associated determinant core motif (ISLAD CM)). Peptides containing the motif interact with the T-cell receptor (TCR) complex; however, the mechanism by which the motif exerts its immunosuppressive activity is yet to be determined. Recent studies showed that interactions between protein domains in the membrane milieu are not always sterically controlled. Therefore, we utilized the unique membrane leniency toward association between D- and L-stereoisomers to investigate the detailed mechanism by which ISLAD CM inhibits T-cell activation. We show that a D-enantiomer of ISLAD CM (termed ISLAD D-CM) inhibited the proliferation of murine myelin oligodendrocyte glycoprotein (MOG)-(35-55)-specific line T-cells to the same extent as the l-motif form. Moreover, the D- and L-forms preferentially bound spleen-derived T-cells over B-cells by 13-fold. Furthermore, both forms of ISLAD CM co-localized with the TCR on activated T-cells and interacted with the transmembrane domain of the TCR. FRET experiments revealed the importance of basic residues for the interaction between ISLAD CM forms and the TCR transmembrane domain. Ex vivo studies demonstrated that ISLAD D-CM administration inhibited the proliferation (72%) and proinflammatory cytokine secretion of pathogenic MOG(35-55)-specific T-cells. This study provides insights into the immunosuppressive mechanism of gp41 and demonstrates that chirality-independent interactions in the membrane can take place in diverse biological systems. Apart from HIV pathogenesis, the D-peptide reported herein may serve as a potential tool for treating T-cell-mediated pathologies.

Cannabinoids decrease the th17 inflammatory autoimmune phenotype

Cannabinoids, the Cannabis constituents, are known to possess anti-inflammatory properties but the mechanisms involved are not understood. Here we show that the main psychoactive cannabinoid, Δ-9-tetrahydrocannabinol (THC), and the main nonpsychoactive cannabinoid, cannabidiol (CBD), markedly reduce the Th17 phenotype which is known to be increased in inflammatory autoimmune pathologies such as Multiple Sclerosis. We found that reactivation by MOG35-55 of MOG35-55-specific encephalitogenic T cells (cells that induce Experimental Autoimmune Encephalitis when injected to mice) in the presence of spleen derived antigen presenting cells led to a large increase in IL-17 production and secretion. In addition, we found that the cannabinoids CBD and THC dose-dependently (at 0.1-5 μM) suppressed the production and secretion of this cytokine. Moreover, the mRNA and protein of IL-6, a key factor in Th17 induction, were also decreased. Pretreatment with CBD also resulted in increased levels of the anti-inflammatory cytokine IL-10. Interestingly, CBD and THC did not affect the levels of TNFα and IFNγ. The downregulation of IL-17 secretion by these cannabinoids does not seem to involve the CB1, CB2, PPARγ, 5-HT1A or TRPV1 receptors. In conclusion, the results show a unique cannabinoid modulation of the autoimmune cytokine milieu combining suppression of the pathogenic IL-17 and IL-6 cytokines along with boosting the expression of the anti-inflammatory cytokine IL-10.

DQB1*0602 rather than DRB1*1501 confers susceptibility to multiple sclerosis-like disease induced by proteolipid protein (PLP)

Background

Multiple sclerosis (MS) is associated with pathogenic autoimmunity primarily focused on major CNS-myelin target antigens including myelin basic protein (MBP), proteolipidprotein (PLP), myelin oligodendrocyte protein (MOG). MS is a complex trait whereby the HLA genes, particularly class-II genes of HLA-DR15 haplotype, dominate the genetic contribution to disease-risk. Due to strong linkage disequilibrium in HLA-II region, it has been hard to establish precisely whether the functionally relevant effect derives from the DRB1*1501, DQA1*0102-DQB1*0602, or DRB5*0101 loci of HLA-DR15 haplotype, their combinations, or their epistatic interactions. Nevertheless, most genetic studies have indicated DRB1*1501 as a primary risk factor in MS. Here, we used 'HLA-humanized' mice to discern the potential relative contribution of DRB1*1501 and DQB1*0602 alleles to susceptibility to "humanized" MS-like disease induced by PLP, one of the most prominent and encephalitogenic target-antigens implicated in human MS.

Methods

The HLA-DRB1*1501- and HLA-DQB1*0602-Tg mice (MHC-II^-/-), and control non-HLA-DR15-relevant-Tg mice were immunized with a set of overlapping PLP peptides or with recombinant soluble PLP for induction of "humanized" MS-like disease, as well as for ex-vivo analysis of immunogenic/immunodominant HLA-restricted T-cell epitopes and associated cytokine secretion profile.

Results

PLP autoimmunity in both HLA-DR15-Tg mice was focused on 139-151 and 175-194 epitopes. Strikingly, however, the HLA-DRB1*1501-transgenics were refractory to disease induction by any of the overlapping PLP peptides, while HLA-DQB1*0602 transgenics were susceptible to disease induction by PLP139-151 and PLP175-194 peptides. Although both transgenics responded to both peptides, the PLP139-151- and PLP175-194-reactive T-cells were directed to Th1/Th17 phenotype in DQB1*0602-Tg mice and towards Th2 in DRB1*1501-Tg mice.

Conclusions

While genome studies map a strong MS susceptibility effect to the region of DRB1*1501, our findings offer a rationale for potential involvement of pathogenic DQ6-associated autoimmunity in MS. Moreover, that DQB1*0602, but not DRB1*1501, determines disease-susceptibility to PLP in HLA-transgenics, suggests a potential differential, functional role for DQB1*0602 as a predisposing allele in MS. This, together with previously demonstrated disease-susceptibility to MBP and MOG in DRB1*1501-transgenics, also suggests a differential role for DRB1*1501 and DQB1*0602 depending on target antigen and imply a potential complex 'genotype/target antigen/phenotype' relationship in MS heterogeneity.

'Multi-epitope-targeted' immune-specific therapy for a multiple sclerosis-like disease via engineered multi-epitope protein is superior to peptides

Antigen-induced peripheral tolerance is potentially one of the most efficient and specific therapeutic approaches for autoimmune diseases. Although highly effective in animal models, antigen-based strategies have not yet been translated into practicable human therapy, and several clinical trials using a single antigen or peptidic-epitope in multiple sclerosis (MS) yielded disappointing results. In these clinical trials, however, the apparent complexity and dynamics of the pathogenic autoimmunity associated with MS, which result from the multiplicity of potential target antigens and “epitope spread”, have not been sufficiently considered. Thus, targeting pathogenic T-cells reactive against a single antigen/epitope is unlikely to be sufficient; to be effective, immunospecific therapy to MS should logically neutralize concomitantly T-cells reactive against as many major target antigens/epitopes as possible. We investigated such “multi-epitope-targeting” approach in murine experimental autoimmune encephalomyelitis (EAE) associated with a single (“classical”) or multiple (“complex”) anti-myelin autoreactivities, using cocktail of different encephalitogenic peptides vis-a-vis artificial multi-epitope-protein (designated Y-MSPc) encompassing rationally selected MS-relevant epitopes of five major myelin antigens, as “multi-epitope-targeting” agents. Y-MSPc was superior to peptide(s) in concomitantly downregulating pathogenic T-cells reactive against multiple myelin antigens/epitopes, via inducing more effective, longer lasting peripheral regulatory mechanisms (cytokine shift, anergy, and Foxp3+ CTLA4+ regulatory T-cells). Y-MSPc was also consistently more effective than the disease-inducing single peptide or peptide cocktail, not only in suppressing the development of “classical” or “complex EAE” or ameliorating ongoing disease, but most importantly, in reversing chronic EAE. Overall, our data emphasize that a “multi-epitope-targeting” strategy is required for effective immune-specific therapy of organ-specific autoimmune diseases associated with complex and dynamic pathogenic autoimmunity, such as MS; our data further demonstrate that the “multi-epitope-targeting” approach to therapy is optimized through specifically designed multi-epitope-proteins, rather than myelin peptide cocktails, as “multi-epitope-targeting” agents. Such artificial multi-epitope proteins can be tailored to other organ-specific autoimmune diseases.

Cannabidiol inhibits pathogenic T cells, decreases spinal microglial activation and ameliorates multiple sclerosis-like disease in C57BL/6 mice

BACKGROUND AND PURPOSE

Cannabis extracts and several cannabinoids have been shown to exert broad anti-inflammatory activities in experimental models of inflammatory CNS degenerative diseases. Clinical use of many cannabinoids is limited by their psychotropic effects. However, phytocannabinoids like cannabidiol (CBD), devoid of psychoactive activity, are, potentially, safe and effective alternatives for alleviating neuroinflammation and neurodegeneration.

EXPERIMENTAL APPROACH

We used experimental autoimmune encephalomyelitis (EAE) induced by myelin oligodendrocyte glycoprotein (MOG) in C57BL/6 mice, as a model of multiple sclerosis. Using immunocytochemistry and cell proliferation assays we evaluated the effects of CBD on microglial activation in MOG-immunized animals and on MOG-specific T-cell proliferation.

KEY RESULTS

Treatment with CBD during disease onset ameliorated the severity of the clinical signs of EAE. This effect of CBD was accompanied by diminished axonal damage and inflammation as well as microglial activation and T-cell recruitment in the spinal cord of MOG-injected mice. Moreover, CBD inhibited MOG-induced T-cell proliferation in vitro at both low and high concentrations of the myelin antigen. This effect was not mediated via the known cannabinoid CB(1) and CB(2) receptors.

CONCLUSIONS AND IMPLICATIONS

CBD, a non-psychoactive cannabinoid, ameliorates clinical signs of EAE in mice, immunized against MOG. Suppression of microglial activity and T-cell proliferation by CBD appeared to contribute to these beneficial effects.

The myelin-associated oligodendrocytic basic protein (MOBP) as a relevant primary target autoantigen in multiple sclerosis

Multiple sclerosis (MS) is a disease of the human CNS, characterized by perivascular inflammation, demyelination and axonal damage. Although the etiology of MS is unknown, it is believed that the disease results from destructive autoimmune mechanisms, presumably initiated by abnormal activation of potentially pathogenic autoimmune T-cells recognizing CNS components. The myelin-associated oligodendrocyte basic protein (MOBP), a relatively abundant CNS-specific myelin protein, which plays a role in stabilizing the myelin sheath in the CNS, has recently been implicated in the pathogenesis of MS. Here we review studies showing that MOBP is as an important candidate target antigen in MS as the other widely studied target antigens, myelin basic protein (MBP), proteolipid protein (PLP), and myelin oligodendrocyte glycoprotein (MOG). The studies summarized below indicate that T-cell autoimmunity against MOBP can be detected in MS patients; T-cells reactive against MOBP can be pathogenic in several mouse strains as well as in the "humanized" HLA-DR15-Tg mice; and, that the HLA-DQ6-restricted, but not HLA-DR15-restricted, MOBP-reactive T-cells cause in HLA-DR15-Tg mice MS-like clinical disease associated with perivascular and parenchymal infiltration, demyelination, axonal loss, and optic neuritis. Accordingly, the MOBP should be considered a bona fide primary target antigen in MS, in addition to MBP, PLP, and MOG.

OSP/claudin-11-induced EAE in mice is mediated by pathogenic T cells primarily governed by OSP192Y residue of major encephalitogenic region OSP179-207

Pathogenic autoimmunity against oligodendrocyte-specific protein (OSP/claudin-11), recently implicated in multiple sclerosis (MS) pathophysiology, has been poorly investigated as compared to that against other myelin encephalitogens. Using recombinant soluble mouse OSP (smOSP) and overlapping peptides thereof, we show that smOSP-induced chronic EAE in C57BL/6J mice is primarily associated with CD4(+) T cells reactive against OSP179-207 and OSP22-46, the major and minor encephalitogenic regions, respectively, and with a predominant B cell response against OSP22-46. The encephalitogenic OSP179-207-specific T cells recognized OSP190-202 as minimal stimulatory epitope, while minimal encephalitogenic sequence was OSP191-199. Further delineation and structural bioinformatic analysis of the major encephalitogenic region suggested four overlapping potential I-A(b) core epitopes, predicting OSP192Y as major TCR-contact residue shared by OSP 188-196, OSP190-198, and OSP191-199 cores, albeit at different MHC-II pockets. Accordingly, substitution at OSP192Y yielded OSP188-192A-202, a non-stimulatory/non-encephalitogenic altered peptide ligand (APL) that was antagonistic for OSP188-202-specific encephalitogenic T cells. Systemic administration of OSP188-192A-202 suppressed OSP188-202-induced EAE and fully reversed smOSP-induced EAE. These data suggest that a single epitopic residue (OSP192Y) governs the selection and control of most pathogenic T cells associated with smOSP-induced EAE in H-2(b) mice. This may impact profoundly on peripheral self-tolerance to OSP and on potential APL-mediated therapy of OSP-related autoimmune pathogenesis.

Epitope specificity of autoreactive T and B cells associated with experimental autoimmune encephalomyelitis and optic neuritis induced by oligodendrocyte-specific protein in SJL/J mice

The encephalitogenic potential of oligodendrocyte-specific protein (OSP) in mice, its specific localization in the intralamellar tight junctions in CNS myelin, and the detection of autoreactivity against OSP in multiple sclerosis (MS) strongly suggest the relevance of autoreactivity against OSP in the pathogenesis of MS. In this study, we have characterized the autoimmune T and B cells that are associated with clinicopathological manifestations of OSP-induced MS-like disease in mice by using recombinant soluble mouse OSP (smOSP) and synthetic overlapping peptides spanning smOSP. SJL/J mice immunized with smOSP developed chronic relapsing clinical experimental autoimmune encephalomyelitis accompanied with intense perivascular and parenchymal inflammatory infiltrates, widespread demyelination, axonal loss, and remarkable optic neuritis. The smOSP-primed lymph node cells reacted predominantly against OSP55-80 and to a lesser extent also to OSP22-46 and OSP179-207. Unexpectedly, in vitro selection with smOSP resulted in pathogenic smOSP-specific CD4+ T cells that reacted equally well against OSP55-80, OSP22-46, OSP45-66, and OSP179-207. Fine analysis of the anti-OSP autoimmunity revealed that the disease is primarily associated with CD4+ T cells directed against the major (OSP55-80) and the minor (OSP179-207) encephalitogenic regions that were further delineated, both in vitro and in vivo, to OSP55-66 and OSP194-207, respectively. In contrast, the OSP-induced Abs were predominantly directed against OSP22-46; these Abs were mostly of IgG1 isotype, but high levels of IgG2a and IgG2b and significant levels of IgE were also observed. The reactivity of pathogenic T cells to two encephalitogenic regions, OSP55-80 and OSP179-207, and their diverse TCRVbeta gene repertoire may impose difficulties for epitope-directed or TCR-targeting approaches to immune-specific modulation of OSP-related pathogenesis.

Anatomy of T cell autoimmunity to myelin oligodendrocyte glycoprotein (MOG): Prime role of MOG44F in selection and control of MOG-reactive T cells in H-2b mice

Myelin oligodendrocyte glycoprotein (MOG) is an important myelin target antigen, and MOG-induced EAE is now a widely used model for multiple sclerosis. Clonal dissection revealed that MOG-induced EAE in H-2(b) mice is associated with activation of an unexpectedly large number of T cell clones reactive against the encephalitogenic epitope MOG35-55. These clones expressed extremely diverse TCR with no obvious CDR3alpha/CDR3beta motif(s). Despite extensive TCR diversity, the cells required MOG40-48 as their common core epitope and shared MOG44F as their major TCR contact. Fine epitope-specificity analysis with progressively truncated peptides suggested that the extensive TCR heterogeneity is mostly related to differential recognition of multiple overlapping epitopes nested within MOG37-52, each comprised of a MOG40-48 core flanked at the N- and/or the C-terminus by a variable number of residues important for interaction with different TCR. Abrogation of both the encephalitogenic potential of MOG and T cell reactivity against MOG by a single mutation (MOG44F/MOG44A), together with effective down-regulation of MOG-induced EAE by MOG37-44A-52, confirmed in vivo the primary role for MOG44F in the selection/activation of MOG-reactive T cells. We suggest that such a highly focused T cell autoreactivity could be a selective force that offsets the extensive TCR diversity to facilitate a more "centralized control" of pathogenic MOG-related T cell autoimmunity.

Acoustic and optical transduction of BuChE binding to procainamide modified surfaces

A novel polymer, poly(procainamide), PPA, containing numerous binding sites for cholinesterases was synthesized as a recognition layer for butyryl cholinesterase (BuChE) interaction with the ligand procainamide, utilizing TSM and SPR sensors. The polymer was synthesized by the reaction of methacryloyl chloride and procainamide followed by radical polymerization. Sensor surfaces (Au or SiO(2)) were spin-coated by the polymer solution to form thin layers. Binding of BuChE was found to be sensitive to the drying procedure of the polymer layer. The binding of BuChE to the polymer coated sensors was monitored on-line by following the response of thickness shear mode (TSM) and surface plasmon resonance (SPR) sensors. Binding of BuChE to PPA-coated TSM sensors were shown to follow a Langmuir isotherm giving association constant 3.4x10(6) M(-1).