Axonal cytoskeleton changes in experimental optic neuritis

Timing of immunotherapeutic strategies for first-episode Isolated Anti-Myelin Oligodendrocyte Glycoprotein-IgG Associated Optic Neuritis: A single-centre retrospective study

Background

There is no consensus on the timing of immunotherapeutic strategies for the first-episode anti-myelin oligodendrocyte glycoprotein-IgG (MOG-IgG) associated disorders (MOGAD) presenting with isolated optic neuritis (ON).

Objective

To investigate the optimal timing of intravenous methylprednisolone therapy (IVMP) and necessity of immunosuppressive therapy for the first-episode isolated MOG-IgG associated ON (iMOG-ON).

Methods

Adult patients with the first-episode iMOG-ON were enrolled. Primary outcomes were best-corrected visual acuity (BCVA) at last follow-up (i.e. final BCVA) and relapse, and their predictors were assessed by multivariate analysis.

Results

62 patients were included. Logistic regression analysis revealed BCVA at the time of IVMP (odds ratio: 0.463 (95 % confidence interval (CI) 0.310-0.714) was a factor predictive of regaining a final BCVA of 0.0 logMAR vision, and its Youden optimal criterion was <0.175 logMAR by plotting the receiver operating characteristic curve. The time-dependent cox proportional hazards model exhibited MMF therapy was not associated with a high likelihood of relapse-free survival (HR = 1.099, 95 % CI 0.892-1.354, P = 0.376) after adjusting for age of onset, gender, and baseline MOG serum titers. Similar analysis exhibited evidently negative association between high MOG-IgG serum titers at baseline and relapse-free survival after adjusting for age of onset, gender, and MMF therapy (HR = 0.339, 95 % CI 0.155-0.741, P = 0.007).

Conclusions

During the first episode of iMOG-ON, the optimal timing of IVMP may be a short timeframe before visual acuity decreasing to 0.175 logMAR, and MMF therapy may not be recommended for patients with low MOG-IgG serum titers. Further long-term follow-up studies are required to validate these findings.

A 10-Year Single-Center Study of the Clinical Characteristics of Optic Neuritis-Related NMOSD, MS, and Double Seronegative Optic Neuritis, Together with Factors Predicting Visual Outcomes

The clinical characteristics of three types of optic neuritis (double seronegative optic neuritis; DN-ON, Neuromyelitis optica spectrum disorder-related optic neuritis; NMOSD-ON, and multiple sclerosis-related optic neuritis; MS-ON) were examined in order to identify factors that may affect good visual recovery in Thai patients. The study included patients diagnosed with three types of optic neuritis at Rajavithi Hospital between 2011 and 2020. Visual acuity at the end of 12 months was used as the treatment outcome. Multiple logistic regression analysis was used to evaluate potential predictors of good visual recovery. Of the 76 patients, 61 had optic neuritis, with DN-ON as the most common subtype (52.6%). MS-ON patients were significantly younger (28.3 ± 6.6 years, p = 0.002) and there was a female predominance in all subgroups (p = 0.076). NMOSD-ON patients had a significantly higher proportion of poor baseline VA (p < 0.001). None of the NMOSD-ON patients achieved 0.3 logMAR visual recovery in the 12-month period (p = 0.022). A delay in treatment with intravenous methylprednisolone (IVMP) for more than 7 days increased the risk of failure to gain 0.3 logMAR visual recovery by five times (OR 5.29, 95% CI 1.359–20.616, p = 0.016), with NMOSD-ON as the strongest predictor (OR 10.47, 95% CI; 1.095–99.993, p = 0.041). Early treatment with intravenous methylprednisolone may be important for achieving at least 0.3 logMAR visual recovery in Thai patients with optic neuritis.

Does time equal vision in the acute treatment of a cohort of AQP4 and MOG optic neuritis?

Objective

To investigate whether visual disability which is known to accumulate by poor recovery from optic neuritis (ON) attacks can be lessened by early treatment, we investigated whether the time from symptom onset to high-dose IV methylprednisolone (IVMP) affected visual recovery.

Methods

A retrospective study was performed in a consecutive cohort of patients following their first aquaporin-4 (AQP4)-IgG or myelin oligodendrocyte glycoprotein (MOG)-IgG-ON. Best-corrected visual acuity (BCVA) in ON eyes at 3 months (BCVA3mo) was correlated with time to IVMP (days). In cases of bilateral ON, 1 eye was randomly selected.

Results

A total of 29 of 37 patients had ON (27 AQP4-seropositive neuromyelitis optica spectrum disorder [NMOSD] and 9 MOG-IgG-ON), 2 of whom refused treatment. Of the 27 patients included, 10 presented later than 7 days from onset. The median BCVA3mo of patients treated >7 days was 20/100 (interquartile range 20/100-20/200). Patients treated >7 days had an OR of 5.50 (95% CI 0.88-34.46, p = 0.051) of failure to regain 0.0 logMAR vision (20/20) and an OR of 10.0 (95% CI 1.39-71.9) of failure to regain 0.2 logMAR vision (20/30) (p = 0.01) compared with patients treated within 7 days. ROC analysis revealed that the optimal criterion of delay in IVMP initiation was ≤4 days, with a sensitivity and specificity of 71.4% and 76.9%, respectively.

Conclusions

In this retrospective study of ON with AQP4 and MOG-IgG, even a 7-day delay in IVMP initiation was detrimental to vision. These results highlight the importance of early treatment for the long-term visual recovery in this group of patients. A prospective, multicenter study of the effects of timing of IVMP is currently underway.

Classification of evidence

This study provides Class IV evidence that hyperacute treatment of AQP4 and MOG-ON with IVMP increases the chance for good visual recovery (20/20 vision) and that even a greater than 7-day delay in treatment is associated with a higher risk for poor visual recovery.

Guillain-Barré syndrome and optic neuritis after Mycoplasma pneumoniae infection

We report the case of a 12-year-old girl who developed Guillain-Barré syndrome (GBS) and optic neuritis (ON) following Mycoplasma pneumoniae infection. Her symptoms, including bilateral vision impairment and tingling in her hands and right foot, were resolved after methylprednisolone pulse therapy. Serum anti-galactocerebroside (Gal-C) IgM antibodies were detected in our patient. This is the first report of a child with GBS and ON associated with M. pneumoniae infection.

Time is vision in recurrent optic neuritis

In optic neuritis (ON) inflammation precedes onset of demyelination and axonal loss. The anti-inflammatory properties of corticosteroids may be most effective in the early inflammatory phase, but rapid patient recruitment remains a logistic challenge. The aim of the study was to review the effect of time to initiation of treatment on visual outcome in recurrent ON. A retrospective case note review of patients known to our centre with recurrent ON. The primary clinical outcome was change of best corrected high contrast visual acuity (BCVA). The secondary outcome was the change of optical coherence tomography (OCT) thickness of the peripapillary retinal nerve fibre layer (pRNFL) and macular ganglion cell layer (mGCL) from baseline and after a minimum of 3months following the episode of recurrent ON. Of 269 patients with a previous episode of ON, 54 experienced recurrent ON. In total 40 OCT documented episodes of relapsing ON were captured in 19 patients. Treatment within <2days led to better recovery of the BCVA (+0.02) and mGCL (-2.4µm) if compared to delayed treatment (BCVA -0.2, p=0.036, mGCL -25.6µm, p=0.019) or no corticosteroids treatment (BCVA -0.2, p=0.045, GCL -5.0µm, p=0.836). These data suggest a beneficial effect of hyperacute corticosteroid treatment. A pragmatic approach for a prospective treatment trial should consider patients with recurrent ON for logistic reasons.

Experimental optic neuritis induced by the microinjection of lipopolysaccharide into the optic nerve

Optic neuritis (ON) is a condition involving primary inflammation, demyelination, and axonal injury in the optic nerve which leads to retinal ganglion cell (RGC) loss, and visual dysfunction. We investigated the ability of a single microinjection of bacterial lipopolysaccharide (LPS) directly into the optic nerve to induce functional and structural alterations compatible with ON. For this purpose, optic nerves from male Wistar rats remained intact or were injected with vehicle or LPS. The effect of LPS was evaluated at several time points post-injection in terms of: i) visual pathway and retinal function (visual evoked potentials (VEPs) and electroretinograms, (ERGs), respectively), ii) anterograde transport from the retina to its projection areas, iii) consensual pupil light reflex (PLR), iv) optic nerve histology, v) microglia/macrophage reactivity (by Iba-1- and ED1-immunostaining), vi) astrocyte reactivity (by glial fibrillary acid protein-immunostaining), vii) axon number (by toluidine blue staining), vii) demyelination (by myelin basic protein immunoreactivity and luxol fast blue staining), viii) optic nerve ultrastructure, and ix) RGC number (by Brn3a immunoreactivity). LPS induced a significant and persistent decrease in VEP amplitude and PLR, without changes in the ERG. In addition, LPS induced a deficit in anterograde transport, and an early inflammatory response consisting in an increased cellularity, and Iba-1 and ED1-immunoreactivity in the optic nerve, which were followed by changes in axonal density, astrocytosis, demyelination, and axon and RGC loss. These results suggest that the microinjection of LPS into the optic nerve may serve as a new experimental model of primary ON.

Classifying minimally disabled multiple sclerosis patients from resting state functional connectivity

Multiple sclerosis (MS), a variable and diffuse disease affecting white and gray matter, is known to cause functional connectivity anomalies in patients. However, related studies published to-date are post hoc; our hypothesis was that such alterations could discriminate between patients and healthy controls in a predictive setting, laying the groundwork for imaging-based prognosis. Using functional magnetic resonance imaging resting state data of 22 minimally disabled MS patients and 14 controls, we developed a predictive model of connectivity alterations in MS: a whole-brain connectivity matrix was built for each subject from the slow oscillations (<0.11 Hz) of region-averaged time series, and a pattern recognition technique was used to learn a discriminant function indicating which particular functional connections are most affected by disease. Classification performance using strict cross-validation yielded a sensitivity of 82% (above chance at p<0.005) and specificity of 86% (p<0.01) to distinguish between MS patients and controls. The most discriminative connectivity changes were found in subcortical and temporal regions, and contralateral connections were more discriminative than ipsilateral connections. The pattern of decreased discriminative connections can be summarized post hoc in an index that correlates positively (ρ=0.61) with white matter lesion load, possibly indicating functional reorganisation to cope with increasing lesion load. These results are consistent with a subtle but widespread impact of lesions in white matter and in gray matter structures serving as high-level integrative hubs. These findings suggest that predictive models of resting state fMRI can reveal specific anomalies due to MS with high sensitivity and specificity, potentially leading to new non-invasive markers.

Translational research in neurology and neuroscience 2010: multiple sclerosis

Over the past 2 decades, enormous progress has been made with regard to pharmacotherapies for patients with multiple sclerosis. There is perhaps no other subspecialty in neurology in which more agents have been approved that substantially alter the clinical course of a disabling disorder. Many of the pharmaceuticals that are currently approved, in clinical trials, or in preclinical development were initially evaluated in an animal model of multiple sclerosis, experimental autoimmune encephalomyelitis. Two Food and Drug Administration-approved agents (glatiramer acetate and natalizumab) were developed using the experimental autoimmune encephalomyelitis model. This model has served clinician-scientists for many decades to enable understanding the inflammatory cascade that underlies clinical disease activity and disease surrogate markers detected in patients.

New developments in the treatment of optic neuritis

Acute optic neuritis (ON) has various etiologies. The most common presentation is inflammatory, demyelinating, idiopathic, or "typical" ON, which may be associated with multiple sclerosis. This must be differentiated from "atypical" causes of ON, which differ in their clinical presentation, natural history, management, and prognosis. Clinical "red flags" for an atypical cause of ON include absent or persistent pain, exudates and hemorrhages on fundoscopy, very severe, bilateral, or progressive visual loss, and failure to recover. In typical ON, steroids shorten the duration of the attack, but do not influence visual outcome. This is in contrast to atypical ON associated with conditions such as sarcoidosis and neuromyelitis optica, which require aggressive immunosuppression and sometimes plasma exchange. The visual prognosis of typical ON is generally good. The prognosis in atypical ON is more variable. New developments aimed at designing better treatments for patients who fail to recover are discussed, focusing on recent research elucidating mechanisms of damage and recovery in ON. Future therapeutic directions may include enhancing repair processes, such as remyelination or adaptive neuroplasticity, or alternative methods of immunomodulation. Pilot studies investigating the safety and proof-of-principle of stem cell treatment are currently underway.

Brain imaging of multiple sclerosis: the next 10 years

MR imaging has had a major impact on understanding the dynamic neuropathologic findings of multiple sclerosis (MS), early diagnosis of the disease, and clinical trial conduct. The next 10 years can be expected to see further advances with a greater emphasis on large multicenter studies, new techniques and hardware allowing greater imaging sensitivity and resolution, and the exploitation of positron emission tomography molecular imaging for MS. The impact should be felt with a new emphasis on gray matter disease and processes of repair. With new ways of monitoring the disease, new treatment targets should become practical, helping to translate advances in the understanding of immunology and regenerative medicine into novel therapies.

Candidate antigens specifically detected by cerebrospinal fluid-IgG in oligoclonal IgG bands-positive multiple sclerosis patients

The aim of the present study was to detect antigenic proteins that react specifically with cerebrospinal fluid (CSF)-IgG from oligoclonal IgG bands (OB)-positive multiple sclerosis (MS) patients. To identify such antigenic proteins, we developed a rat brain proteome map using 2-DE and applied it to the immunoscreening of brain proteins that react with CSF-IgG but not with serum-IgG in OB-positive MS patients. After sequential MALDI-TOF mass spectrometry, eight proteins [two neuronal proteins (tubulin β-2 and γ enolase-2), HSP-1, Tpi-1 protein and cellular enzymes (creatine kinase, phosphopyruvate hydratase, triosephosphate isomerase and phosphoglycerate kinase-1)] were identified as candidate antigens in seven MS patients. Reactivity to tubulin was seen in Western blotting in four patients, and CSF-specific anti-tubulin IgG was detected in one patient. In addition, CSF-specific anti-gamma enolase IgG was found in another patient. These findings suggest that intrathecal immune responses may occur against a broad range of proteins in MS.

Optical coherence tomography in multiple sclerosis

We do not have currently satisfactory clinical and anatomical correlates to gauge disability in multiple sclerosis. Structural biomarkers (such as MRI) are hindered because they cannot precisely segregate demyelination from axonal elements of tissue injury within the CNS. Axonal degeneration in multiple sclerosis is related to irreversible disability, which suggests that the confirmation of neuroprotective strategies needs highly quantifiable measures of axon loss that can be correlated with reliable measures of physiological function. The coupling of quantifiable measures of visual function with ocular imaging techniques, such as optical coherence tomography, enables us to begin to understand how structural changes in the visual system influence function in patients with multiple sclerosis. In this review, we consider the usefulness of optical imaging of the retina as a biomarker for neurodegeneration in multiple-sclerosis.

Axonal degeneration stimulates the formation of NG2+ cells and oligodendrocytes in the mouse

Proliferation of the adult NG2-expressing oligodendrocyte precursor cells has traditionally been viewed as a remyelination response ensuing from destruction of myelin and oligodendrocytes, and not to the axonal pathology that is also a characteristic of demyelinating disease. To better understand the response of the NG2+ cells to the different components of demyelinating pathology, we investigated the response of adult NG2+ cells to axonal degeneration in the absence of primary myelin or oligodendrocyte pathology. Axonal degeneration was induced in the hippocampal dentate gyrus of adult mice by transection of the entorhino-dentate perforant path projection. The acutely induced degeneration of axons and terminals resulted in a prompt response of NG2+ cells, consisting of morphological transformation, cellular proliferation, and upregulation of NG2 expression days 2-3 after surgery. This was followed by a reduction of cellular NG2 expression to subnormal levels from day 5 to 7 and reappearance of normal appearing NG2+ cells from day 10. Mice that had received repeated injections of bromodeoxyuridine from 24 to 72 h after surgery contained significant numbers of bromodeoxyuridine-incorporating oligodendrocytes in the areas with axonal degeneration at day 7. The results suggest that axonal degeneration induces a unique sequence of changes of NG2+ cells and that a subpopulation of the newly generated NG2+ cells differentiate into oligodendrocytes.

Intrathecal Fas ligand infusion strengthens immunoprivilege of central nervous system and suppresses experimental autoimmune encephalomyelitis

Fas ligand (FasL) is an essential molecule strongly expressed in some immunoprivileged sites, but is expressed at very low levels in normal CNS. In this study, acute experimental autoimmune encephalomyelitis (EAE) was induced in Lewis rats with guinea pig myelin basic protein. Intrathecal infusion of recombinant FasL before EAE onset dose dependently suppressed acute EAE and alleviated pathological inflammation in lumbosacral spinal cord. This treatment greatly increased apoptosis in CNS inflammatory cells, but did not inhibit systemic immune response to myelin basic protein. Systemic administration of a similar dose of rFasL was ineffective. In vitro, encephalitogenic T cells were highly sensitive to rFasL-induced cell death, and activated macrophages were also susceptible. In addition, in vitro rFasL treatment potentiated the immunosuppressive property of rat cerebrospinal fluid. We conclude that intrathecal infusion of rFasL eliminated the initial wave of infiltrating T cells and macrophages, and therefore blocked the later recruitment of inflammatory cells into CNS. Although Fas receptor expression was observed on spinal cord neurons, astrocytes, and oligodendrocytes, no damage to these cells or to the myelin structure was detected after rFasL infusion.

Heightened intrathecal release of axonal cytoskeletal proteins in multiple sclerosis is associated with progressive disease and clinical disability

The pathologic basis of disease progression in multiple sclerosis (MS) is thought to involve axonal degeneration, which contributes to the accumulation of neurological disability. Recent reports suggest that intrathecal concentrations of the neurofilament protein in relapsing remitting MS correlate with disease activity and the degree of disability. We sought to investigate the intrathecal levels of other cytoskeletal components of axons, primarily actin, tubulin and the light subunit of neurofilament (NFL) in patients with progressive MS and relevant controls and correlate results with clinical parameters of disease severity. Cerebrospinal fluid (CSF) concentrations of actin, tubulin and NFL were significantly increased in MS patients when compared to corresponding levels in patients with other inflammatory or non-inflammatory neurological diseases. Moreover, the intrathecal release of actin and tubulin, and to a lesser extent NFL, was significantly more marked in patients with primary and secondary progressive MS when compared to patients with relapsing remitting disease and was correlated with clinical disability. Our findings suggest that progressive MS is associated with the heightened intrathecal release of axonal cytoskeletal proteins, and that CSF actin, tubulin and NFL are reliable markers of axonal damage.