Shifting our attention earlier in the multiple sclerosis disease course

PURPOSE OF REVIEW

Revisions of multiple sclerosis (MS) diagnostic criteria enable clinicians to diagnose patients earlier in the biologic disease course. Prompt initiation of therapy correlates with improved clinical outcomes. This has led to increased attention on the earliest stages of MS, including the MS prodrome and radiologically isolated syndrome (RIS). Here, we review current understanding and approach to patients with preclinical MS.

RECENT FINDINGS

MS disease biology often begins well before the onset of typical MS symptoms, and we are increasingly able to recognize preclinical and prodromal stages of MS. RIS represents the best characterized aspect of preclinical MS, and its diagnostic criteria were recently revised to better capture patients at highest risk of conversion to clinical MS. The first two randomized control trials evaluating disease modifying therapy use in RIS also found that treatment could delay or prevent onset of clinical disease.

SUMMARY

Despite progress in our understanding of the earliest stages of the MS disease course, additional research is needed to systematically identify patients with preclinical MS as well as capture those at risk for developing clinical disease. Recent data suggests that preventive immunomodulatory therapies may be beneficial for high-risk patients with RIS; though management remains controversial.

Low-contrast visual acuity test is associated with central inflammation and predicts disability development in newly diagnosed multiple sclerosis patients

Introduction

The visual system is a prominent site of damage in MS since the earliest phases of the disease. Altered low-contrast visual acuity (LCVA) test has been associated with visual impairment and retinal degeneration, predicting medium- and long-term disability. However, it is unclear whether LCVA may also represent a reliable measure of neuroinflammation and a predictor of disease evolution in the very early stages of MS.

Methods

We explored in a group of 76 consecutive newly diagnosed relapsing-remitting MS (RR-MS) patients without visual impairment or altered visual evoked potentials, the association between LCVA scores at 2.5% and 1.25% and clinical characteristics, including prospective disability evaluated after 1- and 2 years of follow-up. Associations between LCVA and the CSF levels of IL-10 at diagnosis were also analyzed.

Results

A negative correlation was found between LCVA at 2.5% and Expanded Disability Status Scale (EDSS) evaluated at first (Spearman's Rho = -0.349, p = 0.005, n = 62) and second year (Spearman's Rho = -0.418, p < 0.001, n = 62) of follow-up, and negative correlations were found with Multiple Sclerosis Severity Score (MSSS) at first (Spearman's Rho = -0.359, p = 0.004, n = 62) and second year (Spearman's Rho = -0.472, p < 0.001, n = 62). All the data were confirmed by a mixed effect model, considering other clinical variables. A positive correlation was found between the CSF concentrations of IL-10 and LCVA at 2.5% (Spearman's Rho = 0.272, p = 0.020, n = 76), and 1.25% (Spearman's Rho, = 0.276, p = 0.018, n = 76), also evidenced in a linear regression.

Discussion

In MS patients at diagnosis, altered LCVA may be associated with CSF inflammation and represent a useful parameter to identify patients with worse disease course.

Genetic regulation of IL-8 influences disease presentation of multiple sclerosis

BACKGROUND

Individual genetic variability may influence the course of multiple sclerosis (MS). The interleukin (IL)-8C>T rs2227306 single nucleotide polymorphism (SNP) regulates IL-8 activity in other clinical conditions; however, its role in MS has never been investigated.

OBJECTIVES

To explore the association between IL-8 SNP rs2227306, cerebrospinal fluid (CSF) IL-8 concentrations, clinical, and radiological characteristics in a group of newly diagnosed MS patients.

METHODS

In 141 relapsing-remitting (RR)-MS patients, rs2227306 polymorphism, CSF levels of IL-8, clinical, and demographical characteristics were determined. In 50 patients, structural magnetic resonance imaging (MRI) measures were also assessed.

RESULTS

An association between CSF IL-8 and Expanded Disability Status Scale (EDSS) at diagnosis was found in our set of patients (r = 0.207, p = 0.014). CSF IL-8 concentrations were significantly higher in patients carrying the T variant of rs2227306 (p = 0.004). In the same group, a positive correlation emerged between IL-8 and EDSS (r = 0.273, p = 0.019). Finally, a negative correlation between CSF levels of IL-8 and cortical thickness emerged in rs2227306T carriers (r = -0.498, p = 0.005).

CONCLUSION

We describe for the first time a role of SNP rs2227306 of IL-8 gene in regulating the expression and the activity of this inflammatory cytokine in MS.

Distinct Immunological Features of Inflammatory Demyelinating Diseases of the Central Nervous System

OBJECTIVE

The immunological features between neuromyelitis optica spectrum disorder (NMOSD), multiple sclerosis (MS), and myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD), lacked systemic comparisons. Accordingly, we aimed to investigate immunological differences between NMOSD, MS, and MOGAD.

METHODS

Patients with MOGAD, MS, and NMOSD who received immunological tests including cytokine profiles and cytometry analysis of the lymphocyte subgroups were retrospectively reviewed and divided into training and validation sets. Discriminatory models based on immunological data were established to identify optimal classifiers using orthogonal partial least square discriminant analysis (OPLS-DA). Constructed models were tested in another independent cohort.

RESULTS

OPLS-DA of the immunological data from 50 patients (26 NMOSD, 14 MS, and 10 MOGAD) demonstrated the discriminatory values of a relatively low level of T-lymphocyte subsets, especially the CD4+ T cells, in MOGAD; a decreased NK cell, eosinophil, and lymphocyte level; an elevated neutrophil-to-lymphocyte ratio in NMOSD; and a declined IFN-γ-producing CD4+ T cells/Th with an increased IL-8 concentration in MS. All the models (NMOSD vs. MS, NMOSD vs. MOGAD, and MS vs. MOGAD) exhibited a significant predictive value and accuracy (>85%).

CONCLUSIONS

NMOSD, MS, and MOGAD may be different in pathogenesis, and several immunological biomarkers can serve as potential classifiers clinically.

Following the Clues: Usefulness of Biomarkers of Neuroinflammation and Neurodegeneration in the Investigation of HTLV-1-Associated Myelopathy Progression

Human T-lymphotropic virus type 1 (HTLV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is a neurodegenerative disease due to axonal damage of the corticospinal secondary to an inflammatory response against infected T-cells. In the present work, we aimed to evaluate biomarkers of neurodegeneration and neuroinflammation in the definition of HAM/TSP prognosis. Neurofilament light (NfL) and phosphorylated heavy (pNfH) chains, total Tau protein, cellular prion protein (PrPc), inflammatory chemokines, and neopterin were quantified in paired cerebrospinal fluid (CSF) and serum samples from HAM/TSP patients (n=21), HTLV-1 asymptomatic carriers (AC) (n=13), and HTLV-1 seronegative individuals with non-inflammatory non-degenerative neurological disease (normal-pressure hydrocephalus) (n=9) as a control group. HTLV-1 proviral load in peripheral blood mononuclear cells and the expression of chemokine receptors CCR4, CCR5, and CXCR3 in infected CD4⁺ T-cells (HTLV-1 Tax⁺ cells) were also assessed. CSF levels of Tau, NfL, and pNfH were similar between groups, but PrPc and neopterin were elevated in HAM/TSP patients. Most individuals in the control group and all HTLV-1 AC had CSF/serum neopterin ratio < 1.0, and two-thirds of HAM/TSP patients had ratio values > 1.0, which positively correlated with the speed of disease progression and pNfH levels, indicating active neuroinflammation. HAM/TSP patients showed high serum levels of CXCR3-binding chemokines (CXCL9, CXCL10, and CXCL11) and elevated CSF levels of CCL2, CCL3, CCL4, CCL17, CXCL5, CXCL10, and CXCL11. Indeed, CXCL10 concentration in CSF of HAM/TSP patients was 5.8-fold and 8.7-fold higher in than in HTLV-1 AC and controls, respectively, and correlated with CSF cell counts. HAM/TSP patients with typical/rapid disease progression had CSF/serum CXCL10 ratio > 1.0 and a higher frequency of CXCR3⁺Tax⁺CD4⁺ T-cells in blood, which indicated a positive gradient for the migration of infected cells and infiltration into the central nervous system. In conclusion, the slow progression of HAM/TSP abrogates the usefulness of biomarkers of neuronal injury for the disease prognosis. Thus, markers of inflammation provide stronger evidence for HAM/TSP progression, particularly the CSF/serum neopterin ratio, which may contribute to overcome differences between laboratory assays.

A comprehensive review on the role of chemokines in the pathogenesis of multiple sclerosis

Multiple sclerosis (MS) as a chronic inflammatory disorder of the central nervous system (CNS) is thought to be caused by the abnormal induction of immune responses. Chemokines as molecules that can engage leukocytes into the location of inflammation, actively participate in the pathogenesis of MS. Several members of this family of chemo attractants have been shown to be dysregulated in the peripheral blood, cerebrospinal fluid or CNS lesions of MS patients. Studies in animal models of MS particularly experimental autoimmune encephalomyelitis have indicated the critical roles of chemokines in the pathophysiology of MS. In the current review, we summarize the data regarding the role of CCL2, CCL3, CCL4, CCL11, CCL20, CXCL1, CXCL2, CXCL8, CXCL10, CXCL12 and CXCL13 in the pathogenesis of MS.

Emulsified silicone oil is taken up by and induces pro-inflammatory response in primary retinal microglia

Purpose

Silicone oil is used as endotamponade in combination with vitrectomy. Thinning of retinal layers and loss of retinal cells under silicone oil use have been found. Here, we investigate the influence of silicone oil on primary microglia cells.

Methods

Primary microglia cells were prepared from the porcine retina. Microglia identity was assessed with Iba1 staining. Silicone oil was emulsified by sonification. Cell morphology and silicone oil uptake were evaluated by light microscopy after Coomassie blue staining. Cytokine secretion was evaluated with ELISA. Toxicity of silicone oil on microglia and toxic effect of silicone oil–treated microglia on neuronal cell line PC12 were evaluated by MTT or WST assay, respectively.

Results

Microglia took up silicone oil droplets after 72 h of incubation. Silicone oil induced no toxicity but increased the metabolism in microglial cells. In addition, the secretion of IL-6 and IL-8, but not of IL-1ß or TNF-α, was induced. Silicone oil–treated microglia did not exert any neurotoxic effect on differentiated PC12 cells but induced an increase in metabolism.

Conclusion

Emulsified silicone oil changes the activity level of microglia and induces the secretion of IL-6 and IL-8. Neurotoxicity is not induced. Further experiments are required to investigate the long-term effect of silicone oil on microglia and their consequent effect on neuronal cells.

PGL I expression in live bacteria allows activation of a CD206/PPARγ cross-talk that may contribute to successful Mycobacterium leprae colonization of peripheral nerves

Mycobacterium leprae, an obligate intracellular bacillus, infects Schwann cells (SCs), leading to peripheral nerve damage, the most severe leprosy symptom. In the present study, we revisited the involvement of phenolic glycolipid I (PGL I), an abundant, private, surface M. leprae molecule, in M. leprae-SC interaction by using a recombinant strain of M. bovis BCG engineered to express this glycolipid. We demonstrate that PGL I is essential for bacterial adhesion and SC internalization. We also show that live mycobacterium-producing PGL I induces the expression of the endocytic mannose receptor (MR/CD206) in infected cells in a peroxisome proliferator-activated receptor gamma (PPARγ)-dependent manner. Of note, blocking mannose recognition decreased bacterial entry and survival, pointing to a role for this alternative recognition pathway in bacterial pathogenesis in the nerve. Moreover, an active crosstalk between CD206 and the nuclear receptor PPARγ was detected that led to the induction of lipid droplets (LDs) formation and prostaglandin E2 (PGE2), previously described as fundamental players in bacterial pathogenesis. Finally, this pathway was shown to induce IL-8 secretion. Altogether, our study provides evidence that the entry of live M. leprae through PGL I recognition modulates the SC phenotype, favoring intracellular bacterial persistence with the concomitant secretion of inflammatory mediators that may ultimately be involved in neuroinflammation.

Nerve damage is the most severe symptom of leprosy, an ancient disease that continues to be a major health problem in several countries. Nerve damage is due to the ability of Mycobacterium leprae, the etiologic agent, to invade SCs, the glial cells of the peripheral nervous system. Understanding the molecular basis of M. leprae–SC interaction is essential for the creation of new tools aiming to treat and, above all, prevent leprosy neuropathy. This study demonstrates the critical role of PGL I, an M. leprae-abundant specific cell wall lipid, in establishing infection. PGL I is not only a prerequisite in initiating bacterial adhesion to and subsequent invasion of SCs, but also for changing the repertoire of cell surface proteins to allow for the entrance of bacteria via alternative pathways. These new invasive pathways induced by PGL I involve recognition of other bacterial cell surface glycolipids that, in turn, evoke functional changes in the infected cell, including the accumulation of host cell-derived lipids, which favor bacterial survival. These pathways also promote the secretion of inflammatory mediators that may contribute to nerve damage. In an era of translational-oriented research, exploring these receptors in depth could lead to the development of attractive strategies to ensure the targeted intracellular delivery of therapeutics aiming to prevent neuropathy.

A potential impact of Helicobacter pylori-related galectin-3 in neurodegeneration

Neurodegeneration represents a component of the central nervous system (CNS) diseases pathogenesis, either as a disability primary source in the frame of prototype neurodegenerative disorders, or as a secondary effect, following inflammation, hypoxia or neurotoxicity. Galectins are members of the lectin superfamily, a group of endogenous glycan-binding proteins, able to interact with glycosylated receptors expressed by several immune cell types. Glycan-lectin interactions play critical roles in the living systems by involving and mediating a variety of biologically important normal and pathological processes, including cell-cell signaling shaping cell communication, proliferation and migration, immune responses and fertilization, host-pathogen interactions and diseases such as neurodegenerative disorders and tumors. This review focuses in the role of Galectin-3 in shaping responses of the immune system against microbial agents, and concretely, Helicobacter pylori (Hp), thereby potentiating effect of the microbe in areas distant from the ordinary site of colonization, like the CNS. We hereby postulate that gastrointestinal Hp alterations in terms of immune cell functional phenotype, cytokine and chemokine secretion, may trigger systemic responses, thereby conferring implications for remote processes susceptible in immunity disequilibrium, namely, the CNS inflammation and/or neurodegeneration.

Amyloid-β Homeostasis Bridges Inflammation, Synaptic Plasticity Deficits and Cognitive Dysfunction in Multiple Sclerosis

Cognitive deficits are frequently observed in multiple sclerosis (MS), mainly involving processing speed and episodic memory. Both demyelination and gray matter atrophy can contribute to cognitive deficits in MS. In recent years, neuroinflammation is emerging as a new factor influencing clinical course in MS. Inflammatory cytokines induce synaptic dysfunction in MS. Synaptic plasticity occurring within hippocampal structures is considered as one of the basic physiological mechanisms of learning and memory. In experimental models of MS, hippocampal plasticity is profoundly altered by proinflammatory cytokines. Although mechanisms of inflammation-induced hippocampal pathology in MS are not completely understood, alteration of Amyloid-β (Aβ) metabolism is emerging as a key factor linking together inflammation, synaptic plasticity and neurodegeneration in different neurological diseases. We explored the correlation between concentrations of Aβ_1–42 and the levels of some proinflammatory and anti-inflammatory cytokines (interleukin-1β (IL-1β), IL1-ra, IL-8, IL-10, IL-12, tumor necrosis factor α (TNFα), interferon γ (IFNγ)) in the cerebrospinal fluid (CSF) of 103 remitting MS patients. CSF levels of Aβ_1–42 were negatively correlated with the proinflammatory cytokine IL-8 and positively correlated with the anti-inflammatory molecules IL-10 and interleukin-1 receptor antagonist (IL-1ra). Other correlations, although noticeable, were either borderline or not significant. Our data show that an imbalance between proinflammatory and anti-inflammatory cytokines may lead to altered Aβ homeostasis, representing a key factor linking together inflammation, synaptic plasticity and cognitive dysfunction in MS. This could be relevant to identify novel therapeutic approaches to hinder the progression of cognitive dysfunction in MS.

Longitudinal Assessment of Transorbital Sonography, Visual Acuity, and Biomarkers for Inflammation and Axonal Injury in Optic Neuritis

Background and Objective

To investigate the relationship between optic nerve sheath diameter, optic nerve diameter, visual acuity and osteopontin, and neurofilament heavy chain in patients with acute optic neuritis.

Patients and Methods

Sonographic and visual acuity assessment and biomarker measurements were executed in 23 patients with unilateral optic neuritis and in 19 sex- and age-matched healthy controls.

Results

ONSD was thicker on the affected side at symptom onset (median 6.3 mm; interquartile range 6.0–6.5) than after 12 months (5.3 mm; 4.9–5.6; p < 0.001) or than in controls (5.2 mm; 4.8–5.5; p < 0.001). OND was significantly increased in the affected side (3.4 mm; 2.9–3.8) compared to healthy controls (2.7 mm; 2.5–2.9; p < 0.001) and was thicker at baseline than after 12 months (2.8 mm; 2.7–3.0; p < 0.01). Visual acuity improved significantly after 12 months (1.00; 0.90–1.00) compared to onset of symptoms (0.80; 0.40–1.00; p < 0.001). OPN levels were significantly higher in patients at presentation (median 6.44 ng/ml; 2.05–10.06) compared to healthy controls (3.21 ng/ml, 1.34–4.34; p < 0.03). Concentrations of NfH were significantly higher in patients than in controls.

Conclusion

ONSD and OND are increased in the affected eye. OPN and NfH are elevated in patients, confirming the presence of any underlying inflammation and axonal injury.

CXCL13, CXCL10 and CXCL8 as Potential Biomarkers for the Diagnosis of Neurosyphilis Patients

At present, diagnosis for neurosyphilis remains a major clinical challenge. Venereal Disease Research Laboratory (VDRL) titer of the cerebrospinal fluid (CSF) is suboptimally sensitive to diagnose neurosyphilis, which can be negative in neurosyphilis patients, especially in asymptomatic neurosyphilis patients. In the search for biomarkers of neurosyphilis, we investigated the chemokine profile in CSF of neurosyphilis patients and found that the concentrations of CXCL13, CXCL10 and CXCL8 were selectively elevated in neurosyphilis patients and correlated with CSF protein concentration and CSF-VDRL titer. After antibiotic treatment, the concentration of these chemokines was dramatically reduced. The area under the ROC curve (AUC) of CSF CXCL13, CXCL8,CXCL10 and the CSF/serum ratio of CXCL13, CXCL8,CXCL10 in the diagnosis of neurosyphilis were 0.940, 0.899, 0.915, 0.963, 0.846 and 0.926, respectively. The corresponding sensitivities/specificities of CSF CXCL13, CXCL8,CXCL10 and the CSF/serum ratio of CXCL13, CXCL8,CXCL10 in diagnosis of neurosyphilis were 85.4%/89.1%, 79%/90.1% and 79.6%/91.1%, 86.6%/99%, 79%/73.3% and 86%/92.1%, respectively. Our results suggest that the elevated concentrations of CXCL13, CXCL8, and CXCL10 or their increasing CSF/serum ratios may be potential biomarkers of neurosyphilis, particularly for asymptomatic neurosyphilis. Reduced concentration of these chemokines may indicate the prognosis of antibiotic therapy.

Argon mediates protection by interleukin-8 suppression via a TLR2/TLR4/STAT3/NF-κB pathway in a model of apoptosis in neuroblastoma cells in vitro and following ischemia-reperfusion injury in rat retina in vivo

Argon has recently come into scientific focus as a neuroprotective agent. The underlying neuroprotective mechanism remains unknown although toll-like receptors were recently suggested to play an important role. We hypothesized that TLR-associated downstream transcription factors are responsible for argon's effects, leading to anti-apoptotic and anti-inflammatory properties. Apoptosis was induced in human neuroblastoma cells. Immediately afterwards, argon treatment (75 Vol% for 2 h) was initiated. Cells were analyzed, measuring mitochondrial membrane potential, reactive-oxygen-species, annexin-V/propidium iodide staining, transcription factor phosphorylation and binding activity as well as protein and mRNA expression of interleukins. Argon's in vivo effects were analyzed by quantification of retinal ganglion cell density, mRNA expression, serum cytokine analysis and immunohistochemistry after retinal ischemia reperfusion injury (IRI) in rats. Argon diminished rotenone-induced kappa-light-chain-enhancer' of activated B-cells (NF-κB) and signal transducer and activator of transcription 3 (STAT3) but not STAT5 or cAMP-response element-binding protein (CREB) phosphorylation and DNA-binding activity. Argon treatment attenuated apoptosis by preservation of mitochondrial membrane potential and decline in reactive oxygen species (ROS) generation. NF-κB and STAT3 inhibition, as well as TLR2 and TLR4 inhibition reversed argon's effects on IL-8 mRNA expression. Argon attenuated rotenone-induced IL-8 protein and mRNA expression in vitro. Inhibition of TLR2 and 4 attenuated argon's protective effect in vivo reducing IRI driven retinal IL-8 expression. IL-8 expression was found in the retina in co-localization with Müller cells and retinal ganglion cells. Argon mediates its neuroprotective effects by TLR-mediated regulation of transcription factors NF-κB and STAT3, thus decreasing interleukin-8 expression in vitro and in vivo. These findings may open up new opportunities to effectively treat cerebral ischemia and reperfusion injury through the inhalation of argon. Argon exerts its protective effects in vitro and in vivo via toll-like receptors TLR2 and TLR4 signaling, followed by alteration of downstream enzymes. In conclusion, argon mediates its beneficial effects by suppression of STAT3 and NF-κB phosphorylation and subsequent suppression of interleukin IL-8 protein expression. These novel findings may open up opportunities for argon as a therapeutic agent, particularly in the treatment of neuronal injury. Cover image for this issue: doi: 10.1111/jnc.13334.