Programmed death 1 is highly expressed on CD8+ CD57+ T cells in patients with stable multiple sclerosis and inhibits their cytotoxic response to Epstein-Barr virus

Growing evidence points to a deregulated response to Epstein-Barr virus (EBV) in the central nervous system of patients with multiple sclerosis (MS) as a possible cause of disease. We have investigated the response of a subpopulation of effector CD8⁺ T cells to EBV in 36 healthy donors and in 35 patients with MS in active and inactive disease. We have measured the expression of markers of degranulation, the release of cytokines, cytotoxicity and the regulation of effector functions by inhibitory receptors, such as programmed death 1 (PD-1) and human inhibitor receptor immunoglobulin-like transcript 2 (ILT2). We demonstrate that polyfunctional cytotoxic CD8⁺ CD57⁺ T cells are able to kill EBV-infected cells in healthy donors. In contrast, an anergic exhaustion-like phenotype of CD8⁺ CD57⁺ T cells with high expression of PD-1 was observed in inactive patients with MS compared with active patients with MS or healthy donors. Detection of CD8⁺ CD57⁺ T cells in meningeal inflammatory infiltrates from post-mortem MS tissue confirmed the association of this cell phenotype with the disease pathological process. The overall results suggest that ineffective immune control of EBV in patietns with MS during remission may be one factor preceding and enabling the reactivation of the virus in the central nervous system and may cause exacerbation of the disease.

Increased PSA expression on prostate cancer exosomes in in vitro condition and in cancer patients

Prostate specific antigen (PSA) test is the most common, clinically validated test for the diagnosis of prostate cancer (PCa). While neoplastic lesions of the prostate may cause aberrant levels of PSA in the blood, the quantitation of free or complexed PSA poorly discriminates cancer patients from those developing benign lesions, often leading to invasive and unnecessary surgical procedures. Microenvironmental acidity increases exosome release by cancer cells. In this study we evaluated whether acidity, a critical phenotype of malignancy, could influence exosome release and increase the PSA expression in nanovesicles released by PCa cells. To this aim, we exploited Nanoparticle Tracking Analysis (NTA), an immunocapture-based ELISA, and nanoscale flow-cytometry. The results show that microenvironmental acidity induces an increased release of nanovesicles expressing both PSA and the exosome marker CD81. In order to verify whether the changes induced by the local selective pressure of extracellular acidity may correspond to a clinical pathway we used the same approach to evaluate the levels of PSA-expressing exosomes in the plasma of PCa patients and controls, including subjects with benign prostatic hypertrophy (BPH). The results show that only PCa patients have high levels of nanovesicles expressing both CD81 and PSA. This study shows that tumor acidity exerts a selective pressure leading to the release of extracellular vesicles that express both PSA and exosome markers. A comparable scenario was shown in the plasma of prostate cancer patients as compared to both BPH and healthy controls. These results suggest that microenvironmental acidity may represent a key factor which determines qualitatively and quantitatively the release of extracellular vesicles by malignant tumors, including prostate cancer. This condition leads to the spill-over of nanovesicles into the peripheral blood of prostate cancer patients, where the levels of tumor biomarkers expressed by exosomes, such as PSA-exosomes, may represent a novel, non-invasive clinical tool for the screening and early diagnosis of prostate cancer.

Acridine Orange/exosomes increase the delivery and the effectiveness of Acridine Orange in human melanoma cells: A new prototype for theranostics of tumors

Specifically targeted drug delivery systems with low immunogenicity and toxicity are deemed to increase efficacy of cancer chemotherapy. Acridine Orange (AO) is an acidophilic dye with a strong tumoricidal action following excitation with a light source at 466 nm. However, to date the clinical use of AO is limited by the potential side effects elicited by systemic administration. The endogenous nanocarrier exosomes have been recently introduced as a natural delivery system for therapeutic molecules. In this article, we show the outcome of the administration to human melanoma cells of AO charged Exosomes (Exo-AO), in both monolayer and spheroid models. The results showed an extended drug delivery time of Exo-AO to melanoma cells as compared to the free AO, improving the cytotoxicity of AO. This study shows that Exo-AO have a great potential for a real exploitation as a new theranostic approach against tumors based on AO delivered through the exosomes.

Fas-Fas Ligand: Checkpoint of T Cell Functions in Multiple Sclerosis

Fas and Fas Ligand (FasL) are two molecules involved in the regulation of cell death. Their interaction leads to apoptosis of thymocytes that fail to rearrange correctly their T cell receptor (TCR) genes and of those that recognize self-antigens, a process called negative selection; moreover, Fas–FasL interaction leads to activation-induced cell death, a form of apoptosis induced by repeated TCR stimulation, responsible for the peripheral deletion of activated T cells. Both control mechanisms are particularly relevant in the context of autoimmune diseases, such as multiple sclerosis (MS), where T cells exert an immune response against self-antigens. This concept is well demonstrated by the development of autoimmune diseases in mice and humans with defects in Fas or FasL. In recent years, several new aspects of T cell functions in MS have been elucidated, such as the pathogenic role of T helper (Th) 17 cells and the protective role of T regulatory (Treg) cells. Thus, in this review, we summarize the role of the Fas–FasL pathway, with particular focus on its involvement in MS. We then discuss recent advances concerning the role of Fas–FasL in regulating Th17 and Treg cells’ functions, in the context of MS.

Siponimod (BAF312) prevents synaptic neurodegeneration in experimental multiple sclerosis

Background

Data from multiple sclerosis (MS) and the MS rodent model, experimental autoimmune encephalomyelitis (EAE), highlighted an inflammation-dependent synaptopathy at the basis of the neurodegenerative damage causing irreversible disability in these disorders. This synaptopathy is characterized by an imbalance between glutamatergic and GABAergic transmission and has been proposed to be a potential therapeutic target.

Siponimod (BAF312), a selective sphingosine 1-phosphate1,5 receptor modulator, is currently under investigation in a clinical trial in secondary progressive MS patients. We investigated whether siponimod, in addition to its peripheral immune modulation, may exert direct neuroprotective effects in the central nervous system (CNS) of mice with chronic progressive EAE.

Methods

Minipumps allowing continuous intracerebroventricular (icv) infusion of siponimod for 4 weeks were implanted into C57BL/6 mice subjected to MOG_35-55-induced EAE. Electrophysiology, immunohistochemistry, western blot, qPCR experiments, and peripheral lymphocyte counts were performed. In addition, the effect of siponimod on activated microglia was assessed in vitro to confirm the direct effect of the drug on CNS-resident immune cells.

Results

Siponimod administration (0.45 μg/day) induced a significant beneficial effect on EAE clinical scores with minimal effect on peripheral lymphocyte counts. Siponimod rescued defective GABAergic transmission in the striatum of EAE, without correcting the EAE-induced alterations of glutamatergic transmission. We observed a significant attenuation of astrogliosis and microgliosis together with reduced lymphocyte infiltration in the striatum of EAE mice treated with siponimod. Interestingly, siponimod reduced the release of IL-6 and RANTES from activated microglial cells in vitro, which might explain the reduced lymphocyte infiltration. Furthermore, the loss of parvalbumin-positive (PV+) GABAergic interneurons typical of EAE brains was rescued by siponimod treatment, providing a plausible explanation of the selective effects of this drug on inhibitory synaptic transmission.

Conclusions

Altogether, our results show that siponimod has neuroprotective effects in the CNS of EAE mice, which are likely independent of its peripheral immune effect, suggesting that this drug could be effective in limiting neurodegenerative pathological processes in MS.

Altered intestinal permeability in patients with relapsing-remitting multiple sclerosis: A pilot study

BACKGROUND

Alterations of intestinal permeability (IP) may contribute to the pathophysiology of immune-mediated diseases.

OBJECTIVE

We investigated the possible association between IP changes and multiple sclerosis (MS).

METHODS

We studied 22 patients with relapsing-remitting multiple sclerosis (RRMS) and 18 age- and sex-matched healthy donors (HDs), including five twin pairs (one concordant, and four discordant for disease). Measurement of lactulose (L) and mannitol (M; two non-metabolized sugars) levels in urine samples, after an oral load, allowed to quantify gut dysfunction.

RESULTS

The proportion of participants with increased IP was significantly higher in patients than in HDs (16/22 (73%) versus 5/18 (28%); p = 0.001). Accordingly, the L/M urinary ratio showed significantly higher values in patients than in controls ( p = 0.0284). Urinary mannitol concentration was significantly lower in patients than in controls ( p = 0.022), suggesting a deficit of absorption from intestinal lumen. Such changes did not appear related to patients' clinical-radiological features.

CONCLUSION

The relatively high proportion of IP changes in RR-MS patients seems to confirm our work hypothesis and warrants more work to confirm the result on a larger sample, and to understand the implications for related immunological disturbances and intestinal microbiota alterations. Our finding may also have relevance for oral treatments, recently introduced in clinical practice.

Advances in T Helper 17 Cell Biology: Pathogenic Role and Potential Therapy in Multiple Sclerosis

The discovery of the T helper (Th) 17 lineage, involved in the protection against fungal and extracellular bacterial infections, has profoundly revolutionized our current understanding of T cell-mediated responses in autoimmune diseases, including multiple sclerosis (MS). Indeed, recent data demonstrate the pathogenic role of Th17 cells in autoimmune disorders. In particular, studies in MS and in its animal model (EAE, experimental autoimmune encephalomyelitis) have revealed a crucial role of Th17 cells in the pathogenesis of autoimmune demyelinating diseases in both mice and humans. Over the past years, several important aspects concerning Th17 cells have been elucidated, such as the factors which promote or inhibit their differentiation and the effector cytokines which mediate their responses. The identification of the features endowing Th17 cells with high pathogenicity in MS is of particular interest, and discoveries in Th17 cell biology and function could lead to the design of new strategies aimed at modulating the immune response in MS. Here, we will discuss recent advances in this field, with particular focus on the mechanisms conferring pathogenicity in MS and their potential modulation.

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.

A Leukemia-Associated CD34/CD123/CD25/CD99+ Immunophenotype Identifies FLT3-Mutated Clones in Acute Myeloid Leukemia

PURPOSE

We evaluated leukemia-associated immunophenotypes (LAIP) and their correlation with fms-like tyrosine kinase 3 (FLT3) and nucleophosmin (NPM1) gene mutational status in order to contribute a better identification of patients at highest risk of relapse in acute myeloid leukemia (AML).

EXPERIMENTAL DESIGN

Bone marrow samples from 132 patients with AML were analyzed by nine-color multiparametric flow cytometry. We confirmed the presence of the mutation in diagnostic samples and in sorted cells by conventional RT-PCR and by patient-specific RQ-PCR.

RESULTS

Within the CD34(+) cell fraction, we identified a discrete population expressing high levels of the IL3 receptor α-chain (CD123) and MIC-2 (CD99) in combination with the IL2 receptor α-chain (CD25). The presence of this population positively correlated with the internal tandem duplications (ITD) mutation in the FLT3 gene (r = 0.71). Receiver operating characteristics showed that, within the CD34(+) cell fraction a percentage of CD123/CD99/CD25(+) cells ≥11.7% predicted FLT3-ITD mutations with a specificity and sensitivity of >90%. CD34/CD123/CD99/CD25(+) clones were also detectable at presentation in 3 patients with FLT3 wild-type/NPM1(+) AML who relapsed with FLT3-ITD/NPM1(+) AML. Quantitative real-time PCR designed at relapse for each FLT3-ITD in these three cases confirmed the presence of low copy numbers of the mutation in diagnostic samples.

CONCLUSIONS

Our results suggest that the CD34/CD25/CD123/CD99(+) LAIP is strictly associated with FLT3-ITD-positive cells.

FAS-ligand regulates differential activation-induced cell death of human T-helper 1 and 17 cells in healthy donors and multiple sclerosis patients

Functionally distinct T-helper (Th) subsets orchestrate immune responses. Maintenance of homeostasis through the tight control of inflammatory Th cells is crucial to avoid autoimmune inflammation. Activation-Induced Cell Death (AICD) regulates homeostasis of T cells, and it has never been investigated in human Th cells. We generated stable clones of inflammatory Th subsets involved in autoimmune diseases, such as Th1, Th17 and Th1/17 cells, from healthy donors (HD) and multiple sclerosis (MS) patients and we measured AICD. We find that human Th1 cells are sensitive, whereas Th17 and Th1/17 are resistant, to AICD. In particular, Th1 cells express high level of FAS-ligand (FASL), which interacts with FAS and leads to caspases' cleavage and ultimately to cell death. In contrast, low FASL expression in Th17 and Th1/17 cells blunts caspase 8 activation and thus reduces cell death. Interestingly, Th cells obtained from healthy individuals and MS patients behave similarly, suggesting that this mechanism could explain the persistence of inflammatory IL-17-producing cells in autoimmune diseases, such as MS, where their generation is particularly substantial.

Epstein-Barr virus genetic variants are associated with multiple sclerosis

OBJECTIVE

We analyzed the Epstein-Barr nuclear antigen 2 (EBNA2) gene, which contains the most variable region of the viral genome, in persons with multiple sclerosis (MS) and control subjects to verify whether virus genetic variants are involved in disease development.

METHODS

A seminested PCR approach and Sanger sequencing were used to analyze EBNA2 in 53 patients and 38 matched healthy donors (HDs). High-throughput sequencing by Illumina MiSeq was also applied in a subgroup of donors (17 patients and 17 HDs). Patients underwent gadolinium-enhanced MRI and human leucocyte antigen typing.

RESULTS

MS risk significantly correlated with an excess of 1.2 allele (odds ratio [OR] = 5.13; 95% confidence interval [CI] 1.84-14.32; p = 0.016) and underrepresentation of 1.3B allele (OR = 0.23; 95% CI 0.08-0.51; p = 0.0006). We identified new genetic variants, mostly 1.2 allele- and MS-associated (especially amino acid variation at position 245; OR = 9.4; 95% CI 1.19-78.72; p = 0.0123). In all cases, the consensus sequence from deep sequencing confirmed Sanger sequencing (including the cosegregation of newly identified variants with known EBNA2 alleles) and showed that the extent of genotype intraindividual variability was higher than expected: rare EBNA2 variants were detected in all HDs and patients with MS (range 1-17 and 3-19, respectively). EBNA2 variants did not seem to correlate with human leucocyte antigen typing or clinical/MRI features.

CONCLUSIONS

Our study unveils a strong association between Epstein-Barr virus genomic variants and MS, reinforcing the idea that Epstein-Barr virus contributes to disease development.

Endocannabinoid signalling in innate and adaptive immunity

The immune system can be modulated and regulated not only by foreign antigens but also by other humoral factors and metabolic products, which are able to affect several quantitative and qualitative aspects of immunity. Among these, endocannabinoids are a group of bioactive lipids that might serve as secondary modulators, which when mobilized coincident with or shortly after first-line immune modulators, increase or decrease many immune functions. Most immune cells express these bioactive lipids, together with their set of receptors and of enzymes regulating their synthesis and degradation. In this review, a synopsis of the manifold immunomodulatory effects of endocannabinoids and their signalling in the different cell populations of innate and adaptive immunity is appointed, with a particular distinction between mice and human immune system compartments.

Interleukin-1β causes excitotoxic neurodegeneration and multiple sclerosis disease progression by activating the apoptotic protein p53

Background

Understanding how inflammation causes neuronal damage is of paramount importance in multiple sclerosis (MS) and in other neurodegenerative diseases. Here we addressed the role of the apoptotic cascade in the synaptic abnormalities and neuronal loss caused by the proinflammatory cytokines interleukin-1β (IL-1β) and tumor necrosis factor (TNF-α) in brain tissues, and disease progression caused by inflammation in relapsing-remitting MS (RRMS) patients.

Results

The effect of IL-1β, but not of TNF-α, on glutamate-mediated excitatory postsynaptic currents was blocked by pifithrin-α (PFT), inhibitor of p53. The protein kinase C (PKC)/transient receptor potential vanilloid 1 (TRPV1) pathway was involved in IL-1β-p53 interaction at glutamatergic synapses, as pharmacological modulation of this inflammation-relevant molecular pathway affected PFT effects on the synaptic action of IL-1β. IL-1β-induced neuronal swelling was also blocked by PFT, and IL-1β increased the expression of p21, a canonical downstream target of activated p53.

Consistent with these in vitro results, the Pro/Pro genotype of p53, associated with low efficiency of transcription of p53-regulated genes, abrogated the association between IL-1β cerebrospinal fluid (CSF) levels and disability progression in RRMS patients. The interaction between p53 and CSF IL-1β was also evaluated at the optical coherence tomography (OCT), showing that IL-1β-driven neurodegenerative damage, causing alterations of macular volume and of retinal nerve fibre layer thickness, was modulated by the p53 genotype.

Conclusions

Inflammatory synaptopathy and neurodegeneration caused by IL-1β in RRMS patients involve the apoptotic cascade. Targeting IL-1β-p53 interaction might result in significant neuroprotection in MS.

Mutational analysis identifies residues crucial for homodimerization of myeloid differentiation factor 88 (MyD88) and for its function in immune cells

Myeloid differentiation factor 88 (MyD88) is an adaptor protein that transduces intracellular signaling pathways evoked by the Toll-like receptors (TLRs) and interleukin-1 receptors (IL-1Rs). MyD88 is composed of an N-terminal death domain (DD) and a C-terminal Toll/IL-1 receptor (TIR) domain, separated by a short region. Upon ligand binding, TLR/IL-1Rs hetero- or homodimerize and recruit MyD88 through their respective TIR domains. Then, MyD88 oligomerizes via its DD and TIR domain and interacts with the interleukin-1 receptor-associated kinases (IRAKs) to form the Myddosome complex. We performed site-directed mutagenesis of conserved residues that are located in exposed regions of the MyD88-TIR domain and analyzed the effect of the mutations on MyD88 signaling. Our studies revealed that mutation of Glu(183), Ser(244), and Arg(288) impaired homodimerization of the MyD88-TIR domain, recruitment of IRAKs, and activation of NF-κB. Moreover, overexpression of two green fluorescent protein (GFP)-tagged MyD88 mini-proteins (GFP-MyD88151-189 and GFP-MyD88168-189), comprising the Glu(183) residue, recapitulated these effects. Importantly, expression of these dominant negative MyD88 mini-proteins competed with the function of endogenous MyD88 and interfered with TLR2/4-mediated responses in a human monocytic cell line (THP-1) and in human primary monocyte-derived dendritic cells. Thus, our studies identify novel residues of the TIR domain that are crucially involved in MyD88 homodimerization and TLR signaling in immune cells.

Non-myeloablative autologous haematopoietic stem cell transplantation expands regulatory cells and depletes IL-17 producing mucosal-associated invariant T cells in multiple sclerosis

Autologous haematopoietic stem cell transplantation has been tried as one experimental strategy for the treatment of patients with aggressive multiple sclerosis refractory to other immunotherapies. The procedure is aimed at ablating and repopulating the immune repertoire by sequentially mobilizing and harvesting haematopoietic stem cells, administering an immunosuppressive conditioning regimen, and re-infusing the autologous haematopoietic cell product. 'Non-myeloablative' conditioning regimens to achieve lymphocytic ablation without marrow suppression have been proposed to improve safety and tolerability. One trial with non-myeloablative autologous haematopoietic stem cell transplantation reported clinical improvement and inflammatory stabilization in treated patients with highly active multiple sclerosis. The aim of the present study was to understand the changes in the reconstituted immune repertoire bearing potential relevance to its mode of action. Peripheral blood was obtained from 12 patients with multiple sclerosis participating in the aforementioned trial and longitudinally followed for 2 years. We examined the phenotype and function of peripheral blood lymphocytes by cell surface or intracellular staining and multi-colour fluorescence activated cell sorting alone or in combination with proliferation assays. During immune reconstitution post-transplantation we observed significant though transient increases in the proportion of CD4+ FoxP3+ T cells and CD56(high) natural killer cell subsets, which are cell subsets associated with immunoregulatory function. CD8+ CD57+ cytotoxic T cells were persistently increased after therapy and were able to suppress CD4+ T cell proliferation with variable potency. In contrast, a CD161(high) proinflammatory CD8+ T cell subset was depleted at all time-points post-transplantation. Phenotypic characterization revealed that the CD161(high)CD8+ T cells were mucosal-associated invariant T cells, a novel cell population originating in the gut mucosa but expressing the central nervous system-homing receptor CCR6. Detection of mucosal-associated invariant T cells in post-mortem multiple sclerosis brain white matter active lesions confirmed their involvement in the disease pathology. Intracellular cytokine staining demonstrated interferon γ and interleukin 17 production and lack of interleukin 10 production, a pro-inflammatory profile. Mucosal-associated invariant T cell frequency did not change in patients treated with interferon β; and was more depleted after autologous haematopoietic stem cell transplantation than in patients who had received high-dose cyclophosphamide (n = 7) or alemtuzumab (n = 21) treatment alone, suggesting an additive or synergistic effect of the conditioning regime components. We propose that a favourably modified balance of regulatory and pro-inflammatory lymphocytes underlies the suppression of central nervous system inflammation in patients with multiple sclerosis following non-myeloablative autologous haematopoietic stem cell transplantation with a conditioning regimen consisting of cyclophosphamide and alemtuzumab.