Several lines of evidence suggest that multiple sclerosis (MS), like other autoimmune diseases, may be triggered by microbial infections. Pathogens associated with development or exacerbation of MS include bacteria, such as Chlamydia pneumoniae, Staphylococcus aureus-produced enterotoxins that function as superantigens, and viruses of the Herpesviridae (Epstein–Barr virus and human herpes virus 6) and human endogenous retrovirus families. However, to date, no single pathogen has been accepted as causal agent. In addition, common upper respiratory, gastrointestinal, and urogenital tract infections have also been associated with MS exacerbations. Although evidence of an infectious etiology as cause of MS in humans remains inconclusive, microbial agents may modulate the neuroimmunological system of genetically susceptible individuals. Decoding the epidemiological contribution of different microorganisms to MS, along with their pathogenic mechanisms, may help develop new treatment strategies and prevent relapses.
Multiple Sclerosis (MS) is a major cause of neurological disability, which increases predominantly during disease progression as a result of cortical and grey matter structures involvement. The gradual accumulation of disability characteristic of the disease seems to also result from a different set of mechanisms, including in particular immune reactions confined to the Central Nervous System such as: (a) B-cell dysregulation, (b) CD8+ T cells causing demyelination or axonal/neuronal damage, and (c) microglial cell activation associated with neuritic transection found in cortical demyelinating lesions. Other potential drivers of neurodegeneration are generation of oxygen and nitrogen reactive species, and mitochondrial damage, inducing impaired energy production, and intra-axonal accumulation of Ca2+, which in turn activates a variety of catabolic enzymes ultimately leading to progressive proteolytic degradation of cytoskeleton proteins. Loss of axon energy provided by oligodendrocytes determines further axonal degeneration and neuronal loss. Clearly, these different mechanisms are not mutually exclusive and could act in combination. Given the multifactorial pathophysiology of progressive MS, many potential therapeutic targets could be investigated in the future. This remains however, an objective that has yet to be undertaken.
Susac syndrome (SuS) is a disorder thought to be mediated by an autoimmune response towards endothelial cells (ECs), leading to a characteristic clinical triad of encephalopathy, visual disturbances due to branch arterial occlusions (BRAO), and sensorineural hearing impairment (SNHL). Although it is a rare disease, three reasons make it important. First, given its variable presentation, Susac syndrome is underdiagnosed. Second, it is considered an important differential diagnosis in different neurological, psychiatric, ophthalmological and hearing disorders, and consequently is frequently misdiagnosed. Third, in many cases, SuS is diagnosed and treated late, with significant irreversible sequelae including dementia, blindness and hearing loss. Neuropathology findings derived from both SuS patient tissue, and novel transgenic mouse models indicate cytotoxic CD8+ T cells adhere to microvessels, inducing endothelial cell (EC) swelling, vascular narrowing and occlusion, causing microinfarcts. Anti-endothelial cell antibodies are present in serum, in 25% of SuS patients, but it is unclear whether they are etiologically related to the disease, or an epiphenomenon. The clinical triad comprising encephalopathy, BRAOs, and SNHL is considered pathognomonic, although great variability is found in presentation, and natural course of disease. At first evaluation, only 13-30% of patients exhibit the full clinical triad, making diagnosis difficult. Retinal fluorescein angiography, optic coherence tomography, MRI, and tonal audiometry are helpful methods for diagnosing and monitoring disease activity during treatment. By contrast, there are no reliable, objective immune markers to monitor disease activity. Immunosuppression is the current treatment, with high-dose corticosteroid therapy as the mainstay, but additional therapies such as intravenous immunoglobulins, cyclophosphamide, rituximab, and mycophenolate mofetil are often necessary, since the disease can be devastating, causing irreversible organ damage. Unfortunately, low rates of disease, variability in presentation, and paucity of objective biomarkers, make prospective, controlled clinical trials for SuS treatment difficult. Current immunosuppressive treatments are therefore based on empirical evidence, mainly from retrospective case series and expert opinion. In this Review, we draw attention to the need to take SuS considered in the differential diagnosis of different neurological, psychiatric, ophthalmological, and hearing disorders. Furthermore, we summarize our current knowledge of this syndrome, in reference to its pathophysiology, diagnosis, and management, emphasizing the need for prospective and controlled studies that allow a better therapeutic approach.
Objective To investigate the effects of leptin on different T‐cell populations, in order to gain more insight into the link between leptin and obesity. Methods Three hundred and nine RRMS patients and 322 controls participated in a cross‐sectional survey, to confirm whether excess weight/obesity in adolescence or early adulthood increased the risk of MS. Serum leptin levels were determined by ELISA. MBP83–102, and MOG63–87 peptide‐specific T cells lines were expanded from peripheral blood mononuclear cells. Leptin receptor expression was measured by RT‐PCR and flow cytometry. Bcl‐2, p‐STAT3, pERK1/2, and p27kip1 expression were assayed using ELISA, and apoptosis induction was determined by Annexin V detection. Cytokines were assessed by ELISPOT and ELISA, and regulatory T cells (Tregs) by flow cytometry. Results Logistic regression analysis, showed excess weight at age 15, and obesity at 20 years of age increased MS risk (OR = 2.16, P = 0.01 and OR = 3.9, P = 0.01). Leptin levels correlated with BMI in both groups. The addition of Leptin increased autoreactive T‐cell proliferation, reduced apoptosis induction, and promoted proinflammatory cytokine secretion. Obese patients produced more proinflammatory cytokines compared to overweight/normal/underweight subjects. Inverse correlation was found between leptin levels and circulating Treg cells (r = −0.97, P < 0.0001). Leptin inhibited Treg proliferation. Effects of leptin on CD4+CD25− effector T cells were mediated by increased STAT3 and ERK1/2 phosphorylation, and down modulation of the cell cycle inhibitor P27kip1. In contrast, leptin effects on Tregs resulted from decreased phosphorylation of ERK1/2 and upregulation of p27kip1. Interpretation Leptin promotes autoreactive T‐cell proliferation and proinflammatory cytokine secretion, but inhibits Treg‐cell proliferation.
Objective The aim of this retrospective cohort study was to analyze responses to intravenous (IV) phenytoin (PHT) for trigeminal neuralgia (TN) crisis in a group of patients treated at our institution. Background TN is one of the most common causes of facial pain. Its treatment relies on preventive therapy with either carbamazepine or oxcarbazepine. During severe pain episodes, patients may be unable to eat, drink, or even swallow oral medication, requiring in‐hospital treatment. There is scarce evidence to support IV medication use for TN, making management of this condition difficult. Methods We reviewed clinical records of patients with TN crisis consulting the emergency department at a tertiary neurological referral center in Buenos Aires, Argentina, treated with IV PHT as analgesic strategy, and with at least 1‐month posttreatment follow‐up. Demographic features, magnetic resonance imaging findings, and therapeutic management were analyzed. Results Thirty‐nine patients with TN were included, 18 (46.2%) receiving IV PHT more than once (total number of infusions administered, 65). Immediate pain relief was observed in 89.2% (58/65) and 15.4% (10/65) presented side effects. Conclusions We recommend IV PHT as acute rescue treatment in TN crisis.
Acute inflammatory demyelinating polyneuropathy (AIDP) and acute-onset chronic inflammatory demyelinating polyneuropathy (A-CIDP) are conditions presenting overlapping clinical features during early stages (first 4 weeks), although the latter may progress after 8 weeks. The aim of this study was to identify predictive factors contributing to their differential diagnosis. Clinical records of adult patients with AIDP or A-CIDP diagnosed at our institution between January 2006 and July 2017 were retrospectively reviewed. Demographic characteristics, clinical manifestations, cerebrospinal-fluid (CSF) findings, treatment and clinical evolution were analyzed. Nerve conduction studies were performed in all patients with at least 12 months follow-up. A total of 91 patients were included (AIDP, n = 77; A-CIDP, n = 14). The median age was 55.5 years in patients with A-CIDP vs 43 years in AIDP (P = .07). The history of diabetes mellitus was more frequent in A-CIDP (29% vs 8%, P = .04). No significant differences between groups were observed with respect to: human immunodeficiency virus (HIV) status, presence of auto-immune disorder or oncologic disease. Cranial, motor and autonomic nerve involvement rates were similar in both groups. Patients in the A-CIDP group showed higher frequency of proprioceptive disturbances (83% vs 28%; P < .001), sensory ataxia (46% vs 16%; P = .01), and the use of combined immunotherapy with corticoids (29% vs 3%; P = .005). There were no significant differences in CSF findings, intensive care unit (ICU) admission, or mortality rates. During the first 8 weeks both entities are practically indistinguishable. Alterations in proprioception could suggest A-CIDP. Searching for markers that allow early differentiation could favor the onset of corticotherapy without delay.
Mesenchymal stromal cells (MSCs) are more often obtained from adult and extraembryonic tissues, with the latter sources being likely better from a therapeutic perspective. MSCs show tropism towards inflamed or tumourigenic sites. Mechanisms involved in MSC recruitment into tumours are comprehensively analysed, including chemoattractant signalling axes, endothelial adhesion and transmigration. In addition, signals derived from hepatocellular carcinoma (HCC) tumour microenvironment and their influence in MSC tropism and tumour recruitment are dissected, as well as the present controversy regarding their influence on tumour growth and/or metastasis. Finally, evidences available on the use of MSCs and other selected progenitor/stem cells as vehicles of antitumourigenic genes are discussed. A better knowledge of the mechanisms involved in progenitor/stem cell recruitment to HCC tumours is proposed in order to enhance their tumour targeting which may result in improvements in cell-based gene therapy strategies.
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