Haematopoietic Stem Cell Transplantation for the Treatment of Multiple Sclerosis: Recent Advances.

PURPOSE OF REVIEW: Autologous haematopoietic stem cell transplantation (AHSCT) is increasingly considered a treatment option for patients with multiple sclerosis (MS), an autoimmune demyelinating and degenerative disease of the central nervous system (CNS). AHSCT persistently suppresses inflammation and improves the disease course in large proportions of patients with relapsing-remitting (RR) MS. Aim of this article is to review the relevant new knowledge published during the last 3 years. RECENT FINDINGS: Laboratory studies reported confirmatory and new insights into the immunological and biomarker effects of AHSCT. Retrospective clinical studies confirmed excellent outcomes in RRMS, showing possible superior effectiveness over standard therapies and suggesting a possible benefit in early secondary progressive (SP) MS with inflammatory features. New data on risks of infertility and secondary autoimmunity were also reported. Further evidence on the high effectiveness and acceptable safety of AHSCT strengthens its position as a clinical option for aggressive RRMS. Further research is needed to better define its role in treatment-naïve and progressive forms of MS, ideally within randomised clinical trials (RCTs).

BRCA1, PARP1 and γH2AX in acute myeloid leukemia: Role as biomarkers of response to the PARP inhibitor olaparib.

Olaparib (AZD-2281, Ku-0059436) is an orally bioavailable and well-tolerated poly(ADP-ribose) polymerase (PARP) inhibitor currently under investigation in patients with solid tumors. To study the clinical potential of olaparib as a single-agent for the treatment of acute myeloid leukemia (AML) patients, we analyzed the in vitro sensitivity of AML cell lines and primary blasts. Clinically achievable concentrations of olaparib were able to induce cell death in the majority of primary AML case samples (88%) and tested cell lines. At these concentrations, olaparib preferentially killed leukemic blasts sparing normal lymphocytes derived from the same patient and did not substantially affect the viability of normal bone marrow and CD34-enriched peripheral blood cells obtained from healthy donors. Most primary AML analyzed were characterized by low BRCA1 mRNA level and undetectable protein expression that likely contributed to explain their sensitivity to olaparib. Noteworthy, while PARP1 over-expression was detected in blasts not responsive to olaparib, phosphorylation of the histone H2AFX (γH2AX) was associated with drug sensitivity. As to genetic features of tested cases the highest sensitivity was shown by a patient carrying a 11q23 deletion. The high sensitivity of AML blasts and the identification of biomarkers potentially able to predict response and/or resistance may foster further investigation of olaparib monotherapy for AML patients unfit to conventional chemotherapy.

Modulation of monocytes by bioactive lipid anandamide in multiple sclerosis involves distinct Toll-like receptors.

Monocytes are believed to be involved in the immunopathogenesis of multiple sclerosis (MS). The aim of this study was to investigate their role in MS and their immunomodulation by the endocannabinoid system (ECS), a novel target for the treatment of this disease. We compared the level of cytokine production from monocytes in healthy subjects and MS patients upon stimulation with viral or bacterial Toll-like receptors (TLR) and we evaluated the ECS immunomodulatory role in these cells. Here we show that MS monocytes produced more TNF-α, IL-12 and IL-6 following activation of TLR2/4 with LPS or of TLR5 with flagellin, as opposed to TLR7/8 stimulation with R848. Furthermore AEA, the main endocannabinoid, suppressed cytokine production and release from healthy monocytes upon stimulation with both bacterial and viral TLR receptors but not in cells from MS patients, where its immunosuppressive activity was TLR7/8-dependent. Altered expression levels of key ECS members in MS monocytes paralleled these data. Our data disclose a distinct immunomodulatory effect of AEA and an alteration of AEA-related members of the ECS in monocytes from MS patients that involves viral but not bacterial TLR. These findings not only may help to better understand the role of monocytes in MS immunopathogenesis but also could be of help to exploit new endocannabinoid-based drugs that target innate immune cells.

The p38 mitogen-activated protein kinase cascade modulates T helper type 17 differentiation and functionality in multiple sclerosis.

The p38 mitogen-activated protein kinase cascade is required for the induction of a T helper type 17 (Th17) -mediated autoimmune response, which underlies the development and progression of several autoimmune diseases, such as experimental autoimmune encephalomyelitis, the animal model of multiple sclerosis (MS). However, the contribution of p38 phosphorylation to human Th cell differentiation has not been clarified. Here we demonstrate that the p38 signalling pathway is implicated in the generation of Th17 lymphocytes from human CD4(+)  CD27(+)  CD45RA(+) naive T cells, both in healthy donors and in patients affected by the relapsing-remitting form of MS. Our data also indicate that p38 activation is essential for interleukin-17 release from central memory lymphocytes and committed Th17 cell clones. Furthermore, CD4(+) T cells isolated from individuals with relapsing-remitting MS display an altered responsiveness of the p38 cascade, resulting in increased p38 phosphorylation upon stimulation. These findings suggest that the p38 signalling pathway, by modulating the Th17 differentiation and response, is involved in the pathogenesis of MS, and open new perspectives for the use of p38 inhibitors in the treatment of Th17-mediated autoimmune diseases.

Distinct modulation of human myeloid and plasmacytoid dendritic cells by anandamide in multiple sclerosis.

OBJECTIVE: The immunopathogenesis of multiple sclerosis (MS) has always been thought to be driven by chronically activated and autoreactive Th-1 and Th-17 cells. Recently, dendritic cells (DCs) have also been thought to significantly contribute to antigenic spread and to maturation of adaptive immunity, and have been linked with disease progression and exacerbation. However, the role of DCs in MS pathogenesis remains poorly understood. METHODS: We compared the level of cytokine production by myeloid DCs (mDCs) and plasmacytoid DCs (pDCs) in healthy subjects and MS patients, following in vitro stimulation of Toll-like receptors 7/8. We also evaluated the effect of the main endocannabinoid, anandamide (AEA), in these DC subsets and correlated cytokine levels with defects in the endocannabinoid system. RESULTS: mDCs obtained from MS patients produce higher levels of interleukin-12 and interleukin-6, whereas pDCs account for lower levels of interferon-α compared to healthy subjects. AEA significantly inhibited cytokine production from healthy mDCs and pDCs, as well as their ability to induce Th-1 and Th-17 lineages. Moreover, we found that in MS only pDCs lack responsiveness to cytokine inhibition induced by AEA. Consistently, this specific cell subset expresses higher levels of the anandamide hydrolase fatty acid amide hydrolase (FAAH). INTERPRETATION: Our data disclose a distinct immunomodulatory effect of AEA in mDCs and pDCs from MS patients, which may reflect an alteration of the expression of FAAH, thus forming the basis for the rational design of new endocannabinoid-based immunotherapeutic agents targeting a specific cell subset.

Immune cell reconstitution following autologous hematopoietic stem cell transplantation in multiple sclerosis.

Hematopoietic stem cell transplantation (HSCT) is a multistep procedure aimed at eradicating the immune system and replacing it with a new one reconstituted from hematopoietic stem cells which in autologous HSCT (AHSCT) have previously been harvested from the same individual. Over the last two decades, AHSCT has been developed as a treatment option for people affected by aggressive multiple sclerosis (MS), and it exerts a long-standing effect on new inflammation-driven disease activity. The rationale for the use of AHSCT in MS will be discussed, starting from the first observations on experimental models. The mechanisms and kinetics of repopulation (i.e., quantitative recovery) and reconstitution (i.e., qualitative changes) of the immune cell populations will be explored, focusing on immune reconstitution of the T and B cells compartments and briefly covering changes in the innate immune system. Finally, potential immunologic markers of response to treatment will be reviewed. Insights into the supposed mechanism(s) of action of AHSCT will be provided, discussing the leading hypothesis of the "rebuilding" of a newly tolerant immune system, and examining the apparent paradox of the long-standing control of disease activity despite a relatively short-term immunosuppressive effect of the procedure.

Apaf1 plays a pro-survival role by regulating centrosome morphology and function.

The apoptotic protease activating factor 1 (Apaf1) is the main component of the apoptosome, and a crucial factor in the mitochondria-dependent death pathway. Here we show that Apaf1 plays a role in regulating centrosome maturation. By analyzing Apaf1-depleted cells, we have found that Apaf1 loss induces centrosome defects that impair centrosomal microtubule nucleation and cytoskeleton organization. This, in turn, affects several cellular processes such as mitotic spindle formation, cell migration and mitochondrial network regulation. As a consequence, Apaf1-depleted cells are more fragile and have a lower threshold to stress than wild-type cells. In fact, we found that they exhibit low Bcl-2 and Bcl-X(L) expression and, under apoptotic treatment, rapidly release cytochrome c. We also show that Apaf1 acts by regulating the recruitment of HCA66, with which it interacts, to the centrosome. This function of Apaf1 is carried out during the cell life and is not related to its apoptotic role. Therefore, Apaf1 might also be considered a pro-survival molecule, whose absence impairs cell performance and causes a higher responsiveness to stressful conditions.

Reversible CD8 T cell-neuron cross-talk causes aging-dependent neuronal regenerative decline.

Aging is associated with increased prevalence of axonal injuries characterized by poor regeneration and disability. However, the underlying mechanisms remain unclear. In our experiments, RNA sequencing of sciatic dorsal root ganglia (DRG) revealed significant aging-dependent enrichment in T cell signaling both before and after sciatic nerve injury (SNI) in mice. Lymphotoxin activated the transcription factor NF-κB, which induced expression of the chemokine CXCL13 by neurons. This in turn recruited CXCR5+CD8+ T cells to injured DRG neurons overexpressing major histocompatibility complex class I. CD8+ T cells repressed the axonal regeneration of DRG neurons via caspase 3 activation. CXCL13 neutralization prevented CXCR5+CD8+ T cell recruitment to the DRG and reversed aging-dependent regenerative decline, thereby promoting neurological recovery after SNI. Thus, axonal regeneration can be facilitated by antagonizing cross-talk between immune cells and neurons.

Immune Reconstitution Following Autologous Hematopoietic Stem Cell Transplantation for Multiple Sclerosis: A Review on Behalf of the EBMT Autoimmune Diseases Working Party.

Multiple sclerosis (MS) is a central nervous system (CNS) disorder, which is mediated by an abnormal immune response coordinated by T and B cells resulting in areas of inflammation, demyelination, and axonal loss. Disease-modifying treatments (DMTs) are available to dampen the inflammatory aggression but are ineffective in many patients. Autologous hematopoietic stem cell transplantation (HSCT) has been used as treatment in patients with a highly active disease, achieving a long-term clinical remission in most. The rationale of the intervention is to eradicate inflammatory autoreactive cells with lympho-ablative regimens and restore immune tolerance. Immunological studies have demonstrated that autologous HSCT induces a renewal of TCR repertoires, resurgence of immune regulatory cells, and depletion of proinflammatory T cell subsets, suggesting a "resetting" of immunological memory. Although our understanding of the clinical and immunological effects of autologous HSCT has progressed, further work is required to characterize the mechanisms that underlie treatment efficacy. Considering that memory B cells are disease-promoting and stem-like T cells are multipotent progenitors involved in self-regeneration of central and effector memory cells, investigating the reconstitution of B cell compartment and stem and effector subsets of immunological memory following autologous HSCT could elucidate those mechanisms. Since all subjects need to be optimally protected from vaccine-preventable diseases (including COVID-19), there is a need to ensure that vaccination in subjects undergoing HSCT is effective and safe. Additionally, the study of vaccination in HSCT-treated subjects as a means of evaluating immune responses could further distinguish broad immunosuppression from immune resetting.

Inflammation triggers synaptic alteration and degeneration in experimental autoimmune encephalomyelitis.

Neurodegeneration is the irremediable pathological event occurring during chronic inflammatory diseases of the CNS. Here we show that, in experimental autoimmune encephalomyelitis (EAE), a mouse model of multiple sclerosis, inflammation is capable in enhancing glutamate transmission in the striatum and in promoting synaptic degeneration and dendritic spine loss. These alterations occur early in the disease course, are independent of demyelination, and are strongly associated with massive release of tumor necrosis factor-alpha from activated microglia. CNS invasion by myelin-specific blood-borne immune cells is the triggering event, and the downregulation of the early gene Arc/Arg3.1, leading to the abnormal expression and phosphorylation of AMPA receptors, represents a culminating step in this cascade of neurodegenerative events. Accordingly, EAE-induced synaptopathy subsided during pharmacological blockade of AMPA receptors. Our data establish a link between neuroinflammation and synaptic degeneration and calls for early neuroprotective therapies in chronic inflammatory diseases of the CNS.

Lack of effect of cannabis-based treatment on clinical and laboratory measures in multiple sclerosis.

The endocannabinoid system (ECS) is involved in the pathophysiology of multiple sclerosis (MS), and relief from pain and spasticity has been reported in MS patients self-medicating with marijuana. A cannabis-based medication containing Delta(9)-tetrahydrocannabinol and cannabidiol (Sativex) has been approved in some countries for the treatment of MS-associated pain. The effects of this pharmaceutical preparation on other clinically relevant aspects of MS pathophysiology, however, are still unclear. In 20 MS patients, we measured the effects of Sativex on clinically measured spasticity and on neurophysiological and laboratory parameters that correlate with spasticity severity or with the modulation of the ECS. Sativex failed to affect spasticity and stretch reflex excitability. This compound also failed to affect the synthesis and the degradation of the endocannabinoid anandamide, as well as the expression of both CB1 and CB2 cannabinoid receptors in various subpopulations of peripheral lymphocytes.

ATM kinase sustains HER2 tumorigenicity in breast cancer.

ATM kinase preserves genomic stability by acting as a tumour suppressor. However, its identification as a component of several signalling networks suggests a dualism for ATM in cancer. Here we report that ATM expression and activity promotes HER2-dependent tumorigenicity in vitro and in vivo. We reveal a correlation between ATM activation and the reduced time to recurrence in patients diagnosed with invasive HER2-positive breast cancer. Furthermore, we identify ATM as a novel modulator of HER2 protein stability that acts by promoting a complex of HER2 with the chaperone HSP90, therefore preventing HER2 ubiquitination and degradation. As a consequence, ATM sustains AKT activation downstream of HER2 and may modulate the response to therapeutic approaches, suggesting that the status of ATM activity may be informative for the treatment and prognosis of HER2-positive tumours. Our findings provide evidence for ATM's tumorigenic potential revising the canonical role of ATM as a pure tumour suppressor.

Protein repertoire impact of Ubiquitin-Proteasome System impairment: insight into the protective role of beta-estradiol.

The Ubiquitin-Proteasome System (UPS) and the Autophagy-Lysosome Pathways (ALP) are key mechanisms for cellular homeostasis sustenance and protein clearance. A wide number of Neurodegenerative Diseases (NDs) are tied with UPS impairment and have been also described as proteinopathies caused by aggregate-prone proteins, not efficiently removed by proteasome. Despite the large knowledge on proteasome biological role, molecular mechanisms associated with its impairment are still blur. We have pursued a comprehensive proteomic investigation to evaluate the phenotypic rearrangements in protein repertoires associated with a UPS blockage. Different functional proteomic approaches have been employed to tackle UPS impairment impact on human NeuroBlastoma (NB) cell lines responsive to proteasome inhibition by Epoxomicin. 2-Dimensional Electrophoresis (2-DE) separation combined with Mass Spectrometry and Shotgun Proteomics experiments have been employed to design a thorough picture of protein profile. Unsupervised meta-analysis of the collected proteomic data revealed that all the identified proteins relate each other in a functional network centered on beta-estradiol. Moreover we showed that treatment of cells with beta-estradiol resulted in aggregate removal and increased cell survival due to activation of the autophagic pathway. Our data may provide the molecular basis for the use of beta-estradiol in neurodegenerative disorders by induction of protein aggregate removal.

Anandamide suppresses proliferation and cytokine release from primary human T-lymphocytes mainly via CB2 receptors.

BACKGROUND: Anandamide (AEA) is an endogenous lipid mediator that exerts several effects in the brain as well as in peripheral tissues. These effects are mediated mainly by two types of cannabinoid receptors, named CB(1)R and CB(2)R, making AEA a prominent member of the "endocannabinoid" family. Also immune cells express CB(1) and CB(2) receptors, and possess the whole machinery responsible for endocannabinoid metabolism. Not surprisingly, evidence has been accumulated showing manifold roles of endocannabinoids in the modulation of the immune system. However, details of such a modulation have not yet been disclosed in primary human T-cells. METHODOLOGY/SIGNIFICANCE: In this investigation we used flow cytometry and ELISA tests, in order to show that AEA suppresses proliferation and release of cytokines like IL-2, TNF-alpha and INF-gamma from activated human peripheral T-lymphocytes. However, AEA did not exert any cytotoxic effect on T-cells. The immunosuppression induced by AEA was mainly dependent on CB(2)R, since it could be mimicked by the CB(2)R selective agonist JWH-015, and could be blocked by the specific CB(2)R antagonist SR144528. Instead the selective CB(1)R agonist ACEA, or the selective CB(1)R antagonist SR141716, were ineffective. Furthermore, we demonstrated an unprecedented immunosuppressive effect of AEA on IL-17 production, a typical cytokine that is released from the unique CD4+ T-cell subset T-helper 17. CONCLUSIONS/SIGNIFICANCE: Overall, our study investigates for the first time the effects of the endocannabinoid AEA on primary human T-lymphocytes, demonstrating that it is a powerful modulator of immune cell functions. In particular, not only we clarify that CB(2)R mediates the immunosuppressive activity of AEA, but we are the first to describe such an immunosuppressive effect on the newly identified Th-17 cells. These findings might be of crucial importance for the rational design of new endocannabinoid-based immunotherapeutic approaches.

Immunogenic, antigenic, fibrillogenic and inflammatory properties of new simplified beta-amyloid peptides.

The most promising approach in Alzheimer disease immunotherapy is represented by amyloid beta derivatives with low intrinsic neurotoxicity and minimal overall T cell responses. To avoid toxicity and autoimmune response, we have designed a new class of Abeta derivatives through segmentation of the original Abeta[1-42] peptide and application of the glycine substitution modification technology. Abeta[1-16], Abeta[13-28] and Abeta[25-42] fragments were selected in order to retain the major immunogenic sites of the Abeta[1-42] peptide. All peptides showed comparable immunogenicity, and raised antibodies were all able to cross-recognize both Abeta[1-42] and Abeta[1-40] synthetic amyloid forms. Polyclonal antibodies produced against the simplified variants were able to recognize the parent peptide, but not the opposite simplified forms, in strict agreement with the model of independent surfaces of recognition. All Abeta simplified derivatives showed reduced fibrillogenic properties, thus underlining that the introduction of glycine residues in alternating positions allows to obtain modified peptides maintaining the main immunogenic properties of the parent peptides, but with reduced ability to adopt a beta-sheet conformation and therefore a much lower risk of toxicity in humans. In addition, in vitro studies on peripheral blood mononuclear cells (PBMCs) from healthy donors showed that only the Abeta[13-28]+G peptide failed to induce IFN-gamma production, thus suggesting that this molecule could represent a good candidate for potentially safer vaccine therapy to reduce amyloid burden in Alzheimer's disease instead of using toxic Abeta[1-42].

ATM kinase activity modulates Fas sensitivity through the regulation of FLIP in lymphoid cells.

Ataxia telangiectasia (A-T) is a rare cancer-predisposing genetic disease, caused by the lack of functional ATM kinase, a major actor of the double strand brakes (DSB) DNA-damage response. A-T patients show a broad and diverse phenotype, which includes an increased rate of lymphoma and leukemia development. Fas-induced apoptosis plays a fundamental role in the homeostasis of the immune system and its defects have been associated with autoimmunity and lymphoma development. We therefore investigated the role of ATM kinase in Fas-induced apoptosis. Using A-T lymphoid cells, we could show that ATM deficiency causes resistance to Fas-induced apoptosis. A-T cells up-regulate FLIP protein levels, a well-known inhibitor of Fas-induced apoptosis. Reconstitution of ATM kinase activity was sufficient to decrease FLIP levels and to restore Fas sensitivity. Conversely, genetic and pharmacologic ATM kinase inactivation resulted in FLIP protein up-regulation and Fas resistance. Both ATM and FLIP are aberrantly regulated in Hodgkin lymphoma. Importantly, we found that reconstitution of ATM kinase activity decreases FLIP protein levels and restores Fas sensitivity in Hodgkin lymphoma-derived cells. Overall, these data identify a novel molecular mechanism through which ATM kinase may regulate the immune system homeostasis and impair lymphoma development.

Apoptosome-deficient cells lose cytochrome c through proteasomal degradation but survive by autophagy-dependent glycolysis.

Cytochrome c release from mitochondria promotes apoptosome formation and caspase activation. The question as to whether mitochondrial permeabilization kills cells via a caspase-independent pathway when caspase activation is prevented is still open. Here we report that proneural cells of embryonic origin, when induced to die but rescued by apoptosome inactivation are deprived of cytosolic cytochrome c through proteasomal degradation. We also show that, in this context, those cells keep generating ATP by glycolysis for a long period of time and that they keep their mitochondria in a depolarized state that can be reverted. Moreover, under these conditions, such apoptosome-deficient cells activate a Beclin 1-dependent autophagy pathway to sustain glycolytic-dependent ATP production. Our findings contribute to elucidating what the point-of-no-return in apoptosis is. They also help in clarifying the issue of survival of apoptosome-deficient proneural cells under stress conditions. Unraveling this issue could be highly relevant for pharmacological intervention and for therapies based on neural stem cell transfer in the treatment of neurological disorders.

Transcriptional profiling of gamma delta T cells identifies a role for vitamin D in the immunoregulation of the V gamma 9V delta 2 response to phosphate-containing ligands.

Vitamin D is a steroid hormone that, in addition to its well-characterized role in calcium/phosphate metabolism, has been found to have regulatory properties for immune system function. The nuclear vitamin D receptor is widely expressed in tissues, but has also been shown to be regulated by hormones, growth factors, and cytokines. In this study we show that activation of human Vdelta2Vgamma9 T cells by nonpeptidic monoalkyl phosphates such as isopentenyl pyrophosphate leads to the up-regulation of the vitamin D receptor via a pathway that involves the classical isoforms of protein kinase C. We further show that this receptor is active by demonstrating that the ligand 1alpha,25-dihydroxyvitamin D3 (vitD3) significantly inhibits in a dose-dependent fashion phospholigand-induced gammadelta T cell expansion, IFN-gamma production, and CD25 expression. We also show that vitD3 negatively regulates signaling via Akt and ERK and, at high concentrations, potentiates Ag-induced cell death. As such, these data provide further support for the immunoregulatory properties of vitamin D, and suggest that the ability of vitD3 to negatively regulate the proinflammatory activity of gammadelta T cells may contribute to the protection this vitamin affords against inflammatory and autoimmune disorders dependent upon Th1-type responses.

Quantification of T-Cell Receptor Excision Circles (TRECs).

Aging is a natural process that compromises the immune system's functionality increasing the risk of infectious, tumors, and autoimmune diseases. The thymus involution is an age-dependent process characterized by decreased cellularity, peripheral lymphocyte infiltration into the perivascular space, and expansion of adipose tissue. All those modifications hamper the functionality of the organ and lead to a decline of naïve T-cell production with a shrinking of the T-cell repertoire. Thymus atrophy is described in several disorders including autoimmune diseases. The quantification of T-cell receptor excision circles (TRECs) in recent thymus emigrants is a standard procedure to investigate the thymic function. In this chapter, we discuss the methodology used to quantify this molecule in peripheral blood mononuclear cells and isolated CD4+ and CD8+ T cells.