Inflammatory Cascades in the Pathogenesis of Multiple Sclerosis Lesions

Multiple sclerosis (MS) is a disease of the human central nervous system (CNS) characterised by inflammation and demyelination. Initially the MS lesion has a distinct histopathological picture with myelin-positive microglia in the midst of apparently intact myelin but minimal perivascular inflammation. Inflammatory mediators produced by these activated microglia may precipitate the infiltration of mononuclear cells and the overt myelin loss seen in actively demyelinating MS lesions. Nuclear factor-κB (NF-κB) is a transcriptional regulator of proteolytic enzymes, adhesion molecules and inflammatory cytokines which rapidly translates extracellular signals into protein synthesis. The immunocytochemical detection of the transcriptionally active form of NF-κB, but not the inhibitory protein IκBα, in the nuclei of microglia in normal human CNS white matter indicates the capability of microglia to respond rapidly to pathological stimuli in the CNS. Activation of NF-κB in MS plaques, evident from the nuclear localisation of the NF-κB subunits RelA, c-Rel and p50 in macrophages, may propagate inflammatory demyelination through upregulation of NF-κB-controlled macrophage genes for inflammatory mediators. In demyelinating disease the plasmin-matrix metalloprotease (MMP) enzymatic cascade promotes blood-brain barrier (BBB) damage, generation of encephalitogenic myelin peptides and activation of pro-inflammatory cytokines. Constitutive expression of MMPs 1, 2, 3 and 9 in glial cells in normal control white matter was demonstrated by immunocytochemistry. However, the lack of tissue (t-PA) and urokinase (u-PA) plasminogen activators in glial cells and the absence of caseinolytic activity as shown by in situ zymography emphasises the latent nature of the plasmin-MMP cascade in normal CNS tissue. In contrast, the co-localisation of t-PA and u-PA, rate-limiting serine-proteases, and MMPs in macrophages and astrocytes in active MS lesions forms the basis of a functional enzymatic cascade. Furthermore, increased amounts and activity of u-PA and MMP-9 in homogenates of active MS plaques coupled with the presence of caseinolytic activity in foamy macrophages implicates these cells as the major source of MMPs, which cause proteolytic damage in MS. Insulin-like growth factors (IGFs) play an important role in development and myelination in the CNS but can also stimulate phagocytosis and production of inflammatory mediators by macrophages. In active MS lesions binding of IGF-II to the IGF receptor on foamy macrophages may induce mitogenic responses and invasiveness of macrophages which can be further enhanced by MMP-mediated proteolytic removal of inhibitory IGF-binding proteins. Similarly, the potent mitogens IGF-I and insulin may stimulate astrocytosis and gliosis. In contrast, oligodendrocytes in normal-appearing white matter do not express IGFs or IGF-I receptor which implies that the oligodendrocyte response to these remyelinating growth factors is impaired. Therefore, the prevailing role of IGFs in MS lesions may be in line with pro-inflammatory mediators promoting macrophage and astrocyte responses to tissue damage. In conclusion, NF-κB activation in microglia and macrophages upregulates the production of PAs and inflammatory cytokines which trigger the plasmin-MMP cascade, leading to BBB damage and enhanced inflammatory cell migration and demyelination in white matter. Influx of IGFs through the damaged BBB and their increased local production may promote myelin phagocytosis and reactive astrocytosis. In turn IGF-mediated upregulation of PAs in glial cells could provide a feedback amplification of the MMP cascade. Therefore, the findings from these studies bring together three systems of mediators, NF-κB, MMPS and IGFs, into a hypothetical model for the propagation of demyelination in MS lesions

Baclofen-induced dyshidrosiform bullous pemphigoid in a paraplegic patient complicated with methicillin-resistant Staphylococcus aureus (mrsa) and urinary infection

Bullous pemphigoid (BP) is an autoimmune disorder which is usually chronic, with blistering that predominantly affects the skin and occasionally the mucosa, and which includes several different types. One of them is a very rare dyshidrosiform type which is localized on the hands and feet with small or large blisters on the palmoplantar surfaces. BP resulting from a drug reaction is a relatively rare occurrence, and so far more than 50 different medications have been identified as triggers. The aim of this article was to present the case of a paraplegic patient who developed this rare dyshidrosiform type of BP while he was being neurologically treated with baclofen. In spite of therapy with systemic and topical corticosteroids and other measures, successful treatment was achieved only after eliminating baclofen from the patient’s regimen. His general state of health was seriously endangered due to nasal and skin methicillin-resistant Staphylococcus aureus (MRSA), urinary infection, and oral mycosis (soor), and he was at high risk of sepsis and a fatal outcome. Through our efforts, however, we managed to achieve an excellent outcome. According to our knowledge, this was the first case of baclofen-induced dyshidrosiform BP. </p

Baclofen-induced dyshidrosiform bullous pemphigoid in a paraplegic patient complicated with methicillin-resistant Staphylococcus aureus (mrsa) and urinary infection

Bullous pemphigoid (BP) is an autoimmune disorder which is usually chronic, with blistering that predominantly affects the skin and occasionally the mucosa, and which includes several different types. One of them is a very rare dyshidrosiform type which is localized on the hands and feet with small or large blisters on the palmoplantar surfaces. BP resulting from a drug reaction is a relatively rare occurrence, and so far more than 50 different medications have been identified as triggers. The aim of this article was to present the case of a paraplegic patient who developed this rare dyshidrosiform type of BP while he was being neurologically treated with baclofen. In spite of therapy with systemic and topical corticosteroids and other measures, successful treatment was achieved only after eliminating baclofen from the patient’s regimen. His general state of health was seriously endangered due to nasal and skin methicillin-resistant Staphylococcus aureus (MRSA), urinary infection, and oral mycosis (soor), and he was at high risk of sepsis and a fatal outcome. Through our efforts, however, we managed to achieve an excellent outcome. According to our knowledge, this was the first case of baclofen-induced dyshidrosiform BP. </p

Production of IL-16 correlates with CD4+ Th1 inflammation and phosphorylation of axonal cytoskeleton in multiple sclerosis lesions

BACKGROUND: Multiple sclerosis (MS) is a central nervous system-specific autoimmune, demyelinating and neurodegenerative disease. Infiltration of lesions by autoaggressive, myelin-specific CD4+Th1 cells correlates with clinical manifestations of disease. The cytokine IL-16 is a CD4+ T cell-specific chemoattractant that is biased towards CD4+ Th1 cells. IL-16 precursor is constitutively expressed in lymphocytes and during CD4+ T cell activation; active caspase-3 cleaves and releases C-terminal bioactive IL-16. Previously, we used an animal model of MS to demonstrate an important role for IL-16 in regulation of autoimmune inflammation and subsequent axonal damage. This role of IL-16 in MS is largely unexplored. Here we examine the regulation of IL-16 in relation to CD4+ Th1 infiltration and inflammation-related changes of axonal cytoskeleton in MS lesions. METHODS: We measured relative levels of IL-16, active caspase-3, T-bet, Stat-1 (Tyr (701)), and phosphorylated NF(M+H), in brain and spinal cord lesions from MS autopsies, using western blot analysis. We examined samples from 39 MS cases, which included acute, subacute and chronic lesions, as well as adjacent, normal-appearing white and grey matter. All samples were taken from patients with relapsing remitting clinical disease. We employed two-color immunostaining and confocal microscopy to identify phenotypes of IL-16-containing cells in frozen tissue sections from MS lesions. RESULTS: We found markedly increased levels of pro- and secreted IL-16 (80 kD and 22 kD, respectively) in MS lesions compared to controls. Levels of IL-16 peaked in acute, diminished in subacute, and were elevated again in chronic active lesions. Compared to lesions, lower but still appreciable IL-6 levels were measured in normal-appearing white matter adjacent to active lesions. Levels of IL-16 corresponded to increases in active-caspase-3, T-bet and phosphorylated Stat-1. In MS lesions, we readily observed IL-16 immunoreactivity confined to infiltrating CD3+, T-bet+ and active caspase-3+ mononuclear cells. CONCLUSION: We present evidence suggesting that IL-16 production occurs in MS lesions. We show correlations between increased levels of secreted IL-16, CD4+ Th1 cell inflammation, and phosphorylation of axonal cytoskeleton in MS lesions. Overall, the data suggest a possible role for IL-16 in regulation of inflammation and of subsequent changes in the axonal cytoskeleton in MS

Substantial subpial cortical demyelination in progressive multiple sclerosis: have we underestimated the extent of cortical pathology?

Aim: Multiple sclerosis (MS) is an inflammatory demyelinating and neurodegenerative disease. Much of the complex symptomatology relates to pathology outside the classic white matter plaque, whereby lesions of the cortical grey matter, which are difficult to resolve by conventional clinical imaging, are in part predictive of outcome. We investigated the extent of grey matter pathology in whole coronal macrosections to reassess the contribution of cortical pathology to total demyelinating lesion area in progressive MS. Methods: Twenty-two cases of progressive MS were prepared as whole bi-hemispheric macrosections for histology, immunostaining and quantitative analysis of lesion number and relative area, leptomeningeal inflammation and microglial/macrophage activation. Results: Cortical grey matter demyelination was seen in all cases, which was more extensive than in white and deep grey matter (hippocampus, thalamus and basal ganglia) and accounted for 0.8%-60.2% of the entire measurable cortical ribbon. The pattern of cortical grey matter demyelination was predominantly subpial (mean 90.9%, range 60%-100%, of total cortical grey matter lesion area) and cases with the largest areas of subpial cortical lesions had more and larger deep grey matter lesions, greater numbers of activated microglia/macrophages, both in lesions as well as in normal cortical grey matter, together with elevated leptomeningeal inflammation and lymphoid-like structures. White matter lesion area was unchanged when compared with the progressive MS cases with little subpial cortical demyelination. Conclusion: Analysis of whole coronal macrosections reveals cortical demyelination is more extensive than reported by conventional histological methods. Cases of progressive MS with substantial subpial cortical demyelination that is independent of underlying white matter lesion area support the implications that these lesions may in-part arise through different pathogenetic mechanisms. Biomarkers and/or imaging correlates of this subpial pathology are required if we are to fully comprehend the clinical disease process

A Perspective of Coagulation Dysfunction in Multiple Sclerosis and in Experimental Allergic Encephalomyelitis

A key role of both coagulation and vascular thrombosis has been reported since the first descriptions of multiple sclerosis (MS). Subsequently, the observation of a close concordance between perivascular fibrin(ogen) deposition and the occurrence of clinical signs in experimental allergic encephalomyelitis (EAE), an animal model of MS, led to numerous investigations focused on the role of thrombin and fibrin(ogen). Indeed, the activation of microglia, resident innate immune cells, occurs early after fibrinogen leakage in the pre-demyelinating lesion stage of EAE and MS. Thrombin has both neuroprotective and pro-apoptotic effects according to its concentration. After exposure to high concentrations of thrombin, astrocytes become reactive and lose their neuroprotective and supportive functions, microglia proliferate, and produce reactive oxygen species, IL-1β, and TNFα. Heparin inhibits the thrombin generation and suppresses EAE. Platelets play an important role too. Indeed, in the acute phase of the disease, they begin the inflammatory response in the central nervous system by producing of IL-1alpha and triggering and amplifying the immune response. Their depletion, on the contrary, ameliorates the course of EAE. Finally, it has been proven that the use of several anticoagulant agents can successfully improve EAE. Altogether, these studies highlight the role of the coagulation pathway in the pathophysiology of MS and suggest possible therapeutic targets that may complement existing treatments

Unveiling the olfactory proteostatic dissangement in Parkinson's disease by proteome-wide profiling

Olfactory dysfunction is one of the earliest features in Lewy-type alphasynucleinopathies (LTS) such as Parkinson´s disease (PD). However, the underlying molecular mechanisms associated to smell impairment are poorly understood. Applying mass spectrometry-based quantitative proteomics in postmortem olfactory bulbs (OB) across limbic, early-neocortical, and neocortical LTS stages of parkinsonian subjects, a proteostasis impairment was observed, identifying 268 differentially expressed proteins between controls and PD phenotypes. In addition, network-driven proteomics revealed a modulation in ERK1/2, MKK3/6, and PDK1/PKC signalling axis. Moreover, a crossdisease study of selected olfactory molecules in sporadic Alzheimer's disease (AD) cases, revealed different protein derangements in the modulation of Secretagogin (SCGN), Calcyclin binding protein (CACYBP), and Glucosamine 6 phosphate isomerase 2 (GNPDA2) between PD and AD. An inverse correlation between GNPDA2 and α-synuclein protein levels was also reflected in PD cerebrospinal fluid (CSF). Interestingly, PD patients exhibited significantly lower serum GNPDA2 levels than controls (n=82/group). Our study provides important avenues for understanding the OB proteostasis imbalance in PD, deciphering mechanistic clues to the equivalent smell deficits observed in AD and PD pathologies

Alzheimer's disease pathology explains association between dementia with Lewy bodies and APOE-ε4/TOMM40 long poly-T repeat allele variants.

Introduction: The role of TOMM40-APOE 19q13.3 region variants is well documented in Alzheimer's disease (AD) but remains contentious in dementia with Lewy bodies (DLB) and Parkinson's disease dementia (PDD). Methods: We dissected genetic profiles within the TOMM40-APOE region in 451 individuals from four European brain banks, including DLB and PDD cases with/without neuropathological evidence of AD-related pathology and healthy controls. Results: TOMM40-L/APOE-ε4 alleles were associated with DLB (OR TOMM40 -L = 3.61; P value = 3.23 × 10-9; OR APOE -ε4 = 3.75; P value = 4.90 × 10-10) and earlier age at onset of DLB (HR TOMM40 -L = 1.33, P value = .031; HR APOE -ε4 = 1.46, P value = .004), but not with PDD. The TOMM40-L/APOE-ε4 effect was most pronounced in DLB individuals with concomitant AD pathology (OR TOMM40 -L = 4.40, P value = 1.15 × 10-6; OR APOE -ε4 = 5.65, P value = 2.97 × 10-8) but was not significant in DLB without AD. Meta-analyses combining all APOE-ε4 data in DLB confirmed our findings (ORDLB = 2.93, P value = 3.78 × 10-99; ORDLB+AD = 5.36, P value = 1.56 × 10-47). Discussion: APOE-ε4/TOMM40-L alleles increase susceptibility and risk of earlier DLB onset, an effect explained by concomitant AD-related pathology. These findings have important implications in future drug discovery and development efforts in DLB

Cellular and molecular mechanisms underpinning macrophage activation during remyelination

Remyelination is an example of central nervous system (CNS) regeneration, whereby myelin is restored around demyelinated axons, re-establishing saltatory conduction and trophic/metabolic support. In progressive multiple sclerosis, remyelination is limited or fails altogether which is considered to contribute to axonal damage/loss and consequent disability. Macrophages have critical roles in both CNS damage and regeneration, such as remyelination. This diverse range in functions reflects the ability of macrophages to acquire tissue microenvironment-specific activation states. This activation is dynamically regulated during efficient regeneration, with a switch from pro-inflammatory to inflammation-resolution/pro-regenerative phenotypes. Although, some molecules and pathways have been implicated in the dynamic activation of macrophages, such as NFκB, the cellular and molecular mechanisms underpinning plasticity of macrophage activation are unclear. Identifying mechanisms regulating macrophage activation to pro-regenerative phenotypes may lead to novel therapeutic strategies to promote remyelination in multiple sclerosis