Dimethyl fumarate modulates the regulatory T cell response in the mesenteric lymph nodes of mice with experimental autoimmune encephalomyelitis

Dimethyl fumarate (DMF, Tecfidera) is an oral drug utilized to treat relapsing-remitting multiple sclerosis (MS). DMF treatment reduces disease activity in MS. Gastrointestinal discomfort is a common adverse effect of the treatment with DMF. This study aimed to investigate the effect of DMF administration in the gut draining lymph nodes cells of C57BL6/J female mice with experimental autoimmune encephalomyelitis (EAE), an animal model of MS. We have demonstrated that the treatment with DMF (7.5 mg/kg) significantly reduces the severity of EAE. This reduction of the severity is accompanied by the increase of both proinflammatory and anti-inflammatory mechanisms at the beginning of the treatment. As the treatment progressed, we observed an increasing number of regulatory Foxp3 negative CD4 T cells (Tr1), and anti-inflammatory cytokines such as IL-27, as well as the reduction of PGE2 level in the mesenteric lymph nodes of mice with EAE. We provide evidence that DMF induces a gradual anti-inflammatory response in the gut draining lymph nodes, which might contribute to the reduction of both intestinal discomfort and the inflammatory response of EAE. These findings indicate that the gut is the first microenvironment of action of DMF, which may contribute to its effects of reducing disease severity in MS patients.

Diving into the proteomic atlas of SARS-CoV-2 infected cells

The COVID-19 pandemic was initiated by the rapid spread of a SARS-CoV-2 strain. Though mainly classified as a respiratory disease, SARS-CoV-2 infects multiple tissues throughout the human body, leading to a wide range of symptoms in patients. To better understand how SARS-CoV-2 affects the proteome from cells with different ontologies, this work generated an infectome atlas of 9 cell models, including cells from brain, blood, digestive system, and adipocyte tissue. Our data shows that SARS-CoV-2 infection mainly trigger dysregulations on proteins related to cellular structure and energy metabolism. Despite these pivotal processes, heterogeneity of infection was also observed, highlighting many proteins and pathways uniquely dysregulated in one cell type or ontological group. These data have been made searchable online via a tool that will permit future submissions of proteomic data ( https://reisdeoliveira.shinyapps.io/Infectome_App/ ) to enrich and expand this knowledgebase.

Combined Training Improves Gene Expression Related to Immunosenescence in Obese Type 2 Diabetic Individuals

Purpose: The aim of this study was to investigate the effects of moderate combined training (CT) on both the gene expression of pro- and anti-inflammatory markers and senescence in the immune system in peripheral blood mononuclear cells (PBMCs) and subcutaneous adipose tissue (SAT) of obese middle-aged individuals with type 2 diabetes (T2D). Methods: Thirty obese individuals (50.2 ± 9.4 years; body mass index: 31.8 ± 2.3 kg/m²) with T2D underwent 16 weeks of a CT group [CT; aerobic (50-60% of VO2max) plus resistance (50-75% of 1RM) training; 3 times/week, 70 min/session; n = 16)] or a control group (CG, n = 14). Nutritional patterns, muscle strength (1RM), cardiorespiratory fitness (VO2max), waist circumference (WC), body composition (Air Displacement Plethysmograph) and blood collections for biochemical (serum leptin, IL-2, IL-4, IL-6, IL-10, TNF-α and anti-CMV) and molecular (gene expression of leptin, IL-2, IL-4, IL-6, IL-10, TNF-α, PD-1, P16ink4a, CCR7, CD28 and CD27 in PBMCs and SAT) analyses were assessed before (Pre) and after (Post) the 16 weeks of the experimental period. Results: Significant decreases were observed in WC and IL4, TNF-α, PD-1 and CD27 expression in PBMCs for CT. Furthermore, significant increases were observed in 1RM and VO2max for CT after the experimental period. Conclusion: Moderate CT contributed to a reduction in the gene expression of markers associated to chronic inflammation and immunosenescence in PBMCs of obese middle-aged individuals with T2D.

Thymic Innervation Impairment in Experimental Autoimmune Encephalomyelitis

INTRODUCTION

The thymus is the primary lymphoid organ responsible for normal T-cell development. Yet, in abnormal metabolic conditions as well as an acute infection, the organ exhibits morphological and cellular alterations. It is well established that the immune system is in a tidy connection and dependent on the central nervous system (CNS), which regulates thymic function by means of innervation and neurotransmitters. Sympathetic innervation leaves the CNS and spreads through thymic tissue, where nerve endings interact directly or indirectly with thymic cells contributing to their maintenance and development.

METHODS

Herein, we hypothesized that brain damage due to an inflammatory process might elicit alterations upon the thymic-CNS neuroimmune axis, altering not just the sympathetic innervation and neurotransmitter release, but also modifying the thymus microenvironment and T-cell development. We used the well-established multiple sclerosis model of experimental autoimmune encephalomyelitis (EAE), to study putative changes in the thymic neural, lymphoid, and microenvironmental compartments.

RESULTS

We showed that along with EAE clinical development, thymus morphology, and cellular compartments are affected, altering the peripheric T-cell population and modifying the retrograde thymic communication toward the CNS.

CONCLUSION

Altogether, our data suggest that the thymic-CNS neuroimmune bidirectional axis is compromised in EAE. This imbalance may contribute to an increased and uncontrolled auto-immune reaction.

SARS-CoV-2 uses CD4 to infect T helper lymphocytes

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the agent of a major global outbreak of respiratory tract disease known as Coronavirus Disease 2019 (COVID-19). SARS-CoV-2 infects mainly lungs and may cause several immune-related complications, such as lymphocytopenia and cytokine storm, which are associated with the severity of the disease and predict mortality. The mechanism by which SARS-CoV-2 infection may result in immune system dysfunction is still not fully understood. Here, we show that SARS-CoV-2 infects human CD4⁺ T helper cells, but not CD8⁺ T cells, and is present in blood and bronchoalveolar lavage T helper cells of severe COVID-19 patients. We demonstrated that SARS-CoV-2 spike glycoprotein (S) directly binds to the CD4 molecule, which in turn mediates the entry of SARS- CoV-2 in T helper cells. This leads to impaired CD4 T cell function and may cause cell death. SARS-CoV-2-infected T helper cells express higher levels of IL-10, which is associated with viral persistence and disease severity. Thus, CD4-mediated SARS-CoV-2 infection of T helper cells may contribute to a poor immune response in COVID-19 patients.

Defective Induction of IL-27-Mediated Immunoregulation by Myeloid DCs in Multiple Sclerosis

The purpose of this study was to examine whether myeloid dendritic cells (mDCs) from patients with multiple sclerosis (MS) and healthy controls (HCs) become similarly tolerogenic when exposed to IL-27 as this may represent a potential mechanism of autoimmune dysregulation. Our study focused on natural mDCs that were isolated from HCs and MS patient peripheral blood mononuclear cells (PBMCs). After a 24-h treatment with IL-27 ± lipopolysaccharide (LPS), the mDCs were either harvested to identify IL-27-regulated gene expression or co-cultured with naive T-cells to measure how the treated DC affected T-cell proliferation and cytokine secretion. mDCs isolated from HCs but not untreated MS patients became functionally tolerogenic after IL-27 treatment. Although IL-27 induced both HC and untreated MS mDCs to produce similar amounts of IL-10, the tolerogenic HC mDCs expressed PD-L2, IDO1, and SOCS1, while the non-tolerogenic untreated MS mDCs expressed IDO1 and IL-6R. Cytokine and RNA analyses identified two signature blocks: the first identified genes associated with mDC tolerizing responses to IL-27, while the second was associated with the presence of MS. In contrast to mDCs from untreated MS patients, mDCs from HCs and IFNb-treated MS patients became tolerogenic in response to IL-27. The genes differentially expressed in the different donor IL-27-treated mDCs may contain targets that regulate mDC tolerogenic responses.

Phenotypic changes in low-density lipoprotein particles as markers of adverse clinical outcomes in COVID-19

BACKGROUND AND AIMS

Low-density lipoprotein (LDL) plasma concentration decline is a biomarker for acute inflammatory diseases, including coronavirus disease-2019 (COVID-19). Phenotypic changes in LDL during COVID-19 may be equally related to adverse clinical outcomes.

METHODS

Individuals hospitalized due to COVID-19 (n = 40) were enrolled. Blood samples were collected on days 0, 2, 4, 6, and 30 (D0, D2, D4, D6, and D30). Oxidized LDL (ox-LDL), and lipoprotein-associated phospholipase A2 (Lp-PLA2) activity were measured. In a consecutive series of cases (n = 13), LDL was isolated by gradient ultracentrifugation from D0 and D6 and was quantified by lipidomic analysis. Association between clinical outcomes and LDL phenotypic changes was investigated.

RESULTS

In the first 30 days, 42.5% of participants died due to Covid-19. The serum ox-LDL increased from D0 to D6 (p < 0.005) and decreased at D30. Moreover, individuals who had an ox-LDL increase from D0 to D6 to over the 90th percentile died. The plasma Lp-PLA2 activity also increased progressively from D0 to D30 (p < 0.005), and the change from D0 to D6 in Lp-PLA2 and ox-LDL were positively correlated (r = 0.65, p < 0.0001). An exploratory untargeted lipidomic analysis uncovered 308 individual lipids in isolated LDL particles. Paired-test analysis from D0 and D6 revealed higher concentrations of 32 lipid species during disease progression, mainly represented by lysophosphatidyl choline and phosphatidylinositol. In addition, 69 lipid species were exclusively modulated in the LDL particles from non-survivors as compared to survivors.

CONCLUSIONS

Phenotypic changes in LDL particles are associated with disease progression and adverse clinical outcomes in COVID-19 patients and could serve as a potential prognostic biomarker.

Morphological, cellular, and molecular basis of brain infection in COVID-19 patients

Although increasing evidence confirms neuropsychiatric manifestations associated mainly with severe COVID-19 infection, long-term neuropsychiatric dysfunction (recently characterized as part of “long COVID-19” syndrome) has been frequently observed after mild infection. We show the spectrum of cerebral impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, ranging from long-term alterations in mildly infected individuals (orbitofrontal cortical atrophy, neurocognitive impairment, excessive fatigue and anxiety symptoms) to severe acute damage confirmed in brain tissue samples extracted from the orbitofrontal region (via endonasal transethmoidal access) from individuals who died of COVID-19. In an independent cohort of 26 individuals who died of COVID-19, we used histopathological signs of brain damage as a guide for possible SARS-CoV-2 brain infection and found that among the 5 individuals who exhibited those signs, all of them had genetic material of the virus in the brain. Brain tissue samples from these five patients also exhibited foci of SARS-CoV-2 infection and replication, particularly in astrocytes. Supporting the hypothesis of astrocyte infection, neural stem cell–derived human astrocytes in vitro are susceptible to SARS-CoV-2 infection through a noncanonical mechanism that involves spike–NRP1 interaction. SARS-CoV-2–infected astrocytes manifested changes in energy metabolism and in key proteins and metabolites used to fuel neurons, as well as in the biogenesis of neurotransmitters. Moreover, human astrocyte infection elicits a secretory phenotype that reduces neuronal viability. Our data support the model in which SARS-CoV-2 reaches the brain, infects astrocytes, and consequently, leads to neuronal death or dysfunction. These deregulated processes could contribute to the structural and functional alterations seen in the brains of COVID-19 patients.

In silico analysis of mutant epitopes in new SARS-CoV-2 lineages suggest global enhanced CD8+ T cell reactivity and also signs of immune response escape

SARS-CoV-2 variants of concern have emerged since the COVID-19 outburst, notably the lineages detected in the UK, South Africa, and Brazil. Their increased transmissibility and higher viral load put them in the spotlight. Much has been investigated on the ability of those new variants to evade antibody recognition. However, little attention has been given to pre-existing and induced SARS-CoV-2-specific CD8+ T cell responses by new lineages. In this work, we predicted SARS-CoV-2-specific CD8+ T cell epitopes from the main variants of concern and their potential to trigger or hinder CD8+ T cell response by using HLA binding and TCR reactivity in silico predictions. Also, we estimated the population's coverage for different lineages, which accounts for the ability to present a set of peptides based on the most frequent HLA alleles of a given population. We considered binding predictions to 110 ccClass I HLA alleles from 29 countries to investigate differences in the fraction of individuals expected to respond to a given epitope set from new and previous lineages. We observed a higher population coverage for the variant detected in the UK (B.1.1.7), and South Africa (B.1.351), as well as for the Brazilian P.1 lineage, but not P.2, compared to the reference lineage. Moreover, individual mutations such as Spike N501Y and Nucleocapsid D138Y were predicted to have an overall stronger affinity through HLA-I than the reference sequence while Spike E484K shows signs of evasion. In summary, we provided evidence for the existence of potentially immunogenic and conserved epitopes across new SARS-CoV-2 variants, but also mutant peptides exhibiting diminished or abolished HLA-I binding. It also highlights the augmented population coverage for three new lineages. Whether these changes imply more T cell reactivity or potential to evade from CD8+ T cell responses requires experimental verification.

Obesity Increases Gene Expression of Markers Associated With Immunosenescence in Obese Middle-Aged Individuals

Recently, it has been argued that obesity leads to a chronic pro-inflammatory state that can accelerate immunosenescence, predisposing to the early acquisition of an immune risk profile and health problems related to immunity in adulthood. In this sense, the present study aimed to verify, in circulating leukocytes, the gene expression of markers related to early immunosenescence associated with obesity and its possible relationships with the physical fitness in obese adults with type 2 diabetes or without associated comorbidities. The sample consisted of middle-aged obese individuals (body mass index (BMI) between 30-35 kg/m²) with type 2 diabetes mellitus (OBD; n = 17) or without associated comorbidity (OB; n = 18), and a control group of eutrophic healthy individuals (BMI: 20 - 25 kg/m²) of same ages (E; n = 18). All groups (OBD, OB and E) performed the functional analyses [muscle strength (1RM) and cardiorespiratory fitness (VO_2max)], anthropometry, body composition (Air Displacement Plethysmograph), blood collections for biochemical (anti-CMV) and molecular (gene expression of leptin, IL-2, IL-4, IL-6, IL-10, TNF-α, PD-1, P16^ink4a, CCR7, CD28 and CD27) analyses of markers related to immunosenescence. Increased gene expression of leptin, IL-2, IL-4, IL-10, TNF-α, PD-1, P16^ink4a, CCR7 and CD27 was found for the OBD and OB groups compared to the E group. Moreover, VO_2max for the OBD and OB groups was significantly lower compared to E. In conclusion, obesity, regardless of associated disease, induces increased gene expression of markers associated with inflammation and immunosenescence in circulating leukocytes in obese middle-aged individuals compared to a eutrophic group of the same age. Additionally, increased adipose tissue and markers of chronic inflammation and immunosenescence were associated to impairments in the cardiorespiratory capacity of obese middle-aged individuals.

Cytotoxic B Cells in Relapsing-Remitting Multiple Sclerosis Patients

Background

Emerging evidence of antibody-independent functions, as well as the clinical efficacy of anti-CD20 depleting therapies, helped to reassess the contribution of B cells during multiple sclerosis (MS) pathogenesis.

Objective

To investigate whether CD19⁺ B cells may share expression of the serine-protease granzyme-B (GzmB), resembling classical cytotoxic CD8⁺ T lymphocytes, in the peripheral blood from relapsing-remitting MS (RRMS) patients.

Methods

In this study, 104 RRMS patients during different treatments and 58 healthy donors were included. CD8, CD19, Runx3, and GzmB expression was assessed by flow cytometry analyses.

Results

RRMS patients during fingolimod (FTY) and natalizumab (NTZ) treatment showed increased percentage of circulating CD8⁺GzmB⁺ T lymphocytes when compared to healthy volunteers. An increase in circulating CD19⁺GzmB⁺ B cells was observed in RRMS patients during FTY and NTZ therapies when compared to glatiramer (GA), untreated RRMS patients, and healthy donors but not when compared to interferon-β (IFN). Moreover, regarding Runx3, the transcriptional factor classically associated with cytotoxicity in CD8⁺ T lymphocytes, the expression of GzmB was significantly higher in CD19⁺Runx3⁺-expressing B cells when compared to CD19⁺Runx3^- counterparts in RRMS patients.

Conclusions

CD19⁺ B cells may exhibit cytotoxic behavior resembling CD8⁺ T lymphocytes in MS patients during different treatments. In the future, monitoring “cytotoxic” subsets might become an accessible marker for investigating MS pathophysiology and even for the development of new therapeutic interventions.

Neutralisation of SARS-CoV-2 lineage P.1 by antibodies elicited through natural SARS-CoV-2 infection or vaccination with an inactivated SARS-CoV-2 vaccine: an immunological study

BACKGROUND

Mutations accrued by SARS-CoV-2 lineage P.1-first detected in Brazil in early January, 2021-include amino acid changes in the receptor-binding domain of the viral spike protein that also are reported in other variants of concern, including B.1.1.7 and B.1.351. We aimed to investigate whether isolates of wild-type P.1 lineage SARS-CoV-2 can escape from neutralising antibodies generated by a polyclonal immune response.

METHODS

We did an immunological study to assess the neutralising effects of antibodies on lineage P.1 and lineage B isolates of SARS-CoV-2, using plasma samples from patients previously infected with or vaccinated against SARS-CoV-2. Two specimens (P.1/28 and P.1/30) containing SARS-CoV-2 lineage P.1 (as confirmed by viral genome sequencing) were obtained from nasopharyngeal and bronchoalveolar lavage samples collected from patients in Manaus, Brazil, and compared against an isolate of SARS-CoV-2 lineage B (SARS.CoV2/SP02.2020) recovered from a patient in Brazil in February, 2020. Isolates were incubated with plasma samples from 21 blood donors who had previously had COVID-19 and from a total of 53 recipients of the chemically inactivated SARS-CoV-2 vaccine CoronaVac: 18 individuals after receipt of a single dose and an additional 20 individuals (38 in total) after receipt of two doses (collected 17-38 days after the most recent dose); and 15 individuals who received two doses during the phase 3 trial of the vaccine (collected 134-230 days after the second dose). Antibody neutralisation of P.1/28, P.1/30, and B isolates by plasma samples were compared in terms of median virus neutralisation titre (VNT50, defined as the reciprocal value of the sample dilution that showed 50% protection against cytopathic effects).

FINDINGS

In terms of VNT50, plasma from individuals previously infected with SARS-CoV-2 had an 8·6 times lower neutralising capacity against the P.1 isolates (median VNT50 30 [IQR <20-45] for P.1/28 and 30 [<20-40] for P.1/30) than against the lineage B isolate (260 [160-400]), with a binominal model showing significant reductions in lineage P.1 isolates compared with the lineage B isolate (p≤0·0001). Efficient neutralisation of P.1 isolates was not seen with plasma samples collected from individuals vaccinated with a first dose of CoronaVac 20-23 days earlier (VNT50s below the limit of detection [<20] for most plasma samples), a second dose 17-38 days earlier (median VNT50 24 [IQR <20-25] for P.1/28 and 28 [<20-25] for P.1/30), or a second dose 134-260 days earlier (all VNT50s below limit of detection). Median VNT50s against the lineage B isolate were 20 (IQR 20-30) after a first dose of CoronaVac 20-23 days earlier, 75 (<20-263) after a second dose 17-38 days earlier, and 20 (<20-30) after a second dose 134-260 days earlier. In plasma collected 17-38 days after a second dose of CoronaVac, neutralising capacity against both P.1 isolates was significantly decreased (p=0·0051 for P.1/28 and p=0·0336 for P.1/30) compared with that against the lineage B isolate. All data were corroborated by results obtained through plaque reduction neutralisation tests.

INTERPRETATION

SARS-CoV-2 lineage P.1 might escape neutralisation by antibodies generated in response to polyclonal stimulation against previously circulating variants of SARS-CoV-2. Continuous genomic surveillance of SARS-CoV-2 combined with antibody neutralisation assays could help to guide national immunisation programmes.

FUNDING

São Paulo Research Foundation, Brazilian Ministry of Science, Technology and Innovation and Funding Authority for Studies, Medical Research Council, National Council for Scientific and Technological Development, National Institutes of Health.

TRANSLATION

For the Portuguese translation of the abstract see Supplementary Materials section.

Decreased Neurofilament L Chain Levels in Cerebrospinal Fluid and Tolerogenic Plasmacytoid Dendritic Cells in Natalizumab-Treated Multiple Sclerosis Patients - Brief Research Report

Background

Neurofilament Light (NfL) chain levels in both cerebrospinal fluid (CSF) and serum have been correlated with the reduction of axonal damage in multiple sclerosis (MS) patients treated with Natalizumab (NTZ). However, little is known about the function of plasmacytoid cells in NTZ-treated MS patients.

Objective

To evaluate CSF NfL, serum levels of soluble-HLA-G (sHLA-G), and eventual tolerogenic behavior of plasmacytoid dendritic cells (pDCs) in MS patients during NTZ treatment.

Methods

CSF NfL and serum sHLA-G levels were measured using an ELISA assay, while pDCs (BDCA-2⁺) were accessed through flow cytometry analyses.

Results

CSF levels of NfL were significantly reduced during NTZ treatment, while the serum levels of sHLA-G were increased. Moreover, NTZ treatment enhanced tolerogenic (HLA-G⁺, CD274⁺, and HLA-DR⁺) molecules and migratory (CCR7⁺) functions of pDCs in the peripheral blood.

Conclusion

These findings suggest that NTZ stimulates the production of molecules with immunoregulatory function such as HLA-G and CD274 programmed death-ligand 1 (PD-L1) which may contribute to the reduction of axonal damage represented by the decrease of NfL levels in patients with MS.

Respiratory Viral Shedding in Healthcare Workers Reinfected with SARS-CoV-2, Brazil, 2020

We documented 4 cases of severe acute respiratory syndrome coronavirus 2 reinfection by non-variant of concern strains among healthcare workers in Campinas, Brazil. We isolated infectious particles from nasopharyngeal secretions during both infection episodes. Improved and continued protection measures are necessary to mitigate the risk for reinfection among healthcare workers.

Kinetics of peripheral blood neutrophils in severe coronavirus disease 2019

OBJECTIVES

Emerging evidence of dysregulation of the myeloid cell compartment urges investigations on neutrophil characteristics in coronavirus disease 2019 (COVID-19). We isolated neutrophils from the blood of COVID-19 patients receiving general ward care and from patients hospitalised at intensive care units (ICUs) to explore the kinetics of circulating neutrophils and factors important for neutrophil migration and activation.

METHODS

Multicolour flow cytometry was exploited for the analysis of neutrophil differentiation and activation markers. Multiplex and ELISA technologies were used for the quantification of protease, protease inhibitor, chemokine and cytokine concentrations in plasma. Neutrophil polarisation responses were evaluated microscopically. Gelatinolytic and metalloproteinase activity in plasma was determined using a fluorogenic substrate. Co-culturing healthy donor neutrophils with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) allowed us to investigate viral replication in neutrophils.

RESULTS

Upon ICU admission, patients displayed high plasma concentrations of granulocyte-colony-stimulating factor (G-CSF) and the chemokine CXCL8, accompanied by emergency myelopoiesis as illustrated by high levels of circulating CD10-, immature neutrophils with reduced CXCR2 and C5aR expression. Neutrophil elastase and non-metalloproteinase-derived gelatinolytic activity were increased in plasma from ICU patients. Significantly higher levels of circulating tissue inhibitor of metalloproteinase 1 (TIMP-1) in patients at ICU admission yielded decreased total MMP proteolytic activity in blood. COVID-19 neutrophils were hyper-responsive to CXCL8 and CXCL12 in shape change assays. Finally, SARS-CoV-2 failed to replicate inside human neutrophils.

CONCLUSION

Our study provides detailed insights into the kinetics of neutrophil phenotype and function in severe COVID-19 patients, and supports the concept of an increased neutrophil activation state in the circulation.

Safety and Outcomes Associated with the Pharmacological Inhibition of the Kinin-Kallikrein System in Severe COVID-19

Background: Coronavirus disease 19 (COVID-19) can develop into a severe respiratory syndrome that results in up to 40% mortality. Acute lung inflammatory edema is a major pathological finding in autopsies explaining O₂ diffusion failure and hypoxemia. Only dexamethasone has been shown to reduce mortality in severe cases, further supporting a role for inflammation in disease severity. SARS-CoV-2 enters cells employing angiotensin-converting enzyme 2 (ACE2) as a receptor, which is highly expressed in lung alveolar cells. ACE2 is one of the components of the cellular machinery that inactivates the potent inflammatory agent bradykinin, and SARS-CoV-2 infection could interfere with the catalytic activity of ACE2, leading to the accumulation of bradykinin. Methods: In this case control study, we tested two pharmacological inhibitors of the kinin–kallikrein system that are currently approved for the treatment of hereditary angioedema, icatibant, and inhibitor of C1 esterase/kallikrein, in a group of 30 patients with severe COVID-19. Results: Neither icatibant nor inhibitor of C1 esterase/kallikrein resulted in changes in time to clinical improvement. However, both compounds were safe and promoted the significant improvement of lung computed tomography scores and increased blood eosinophils, which are indicators of disease recovery. Conclusions: In this small cohort, we found evidence for safety and a beneficial role of pharmacological inhibition of the kinin–kallikrein system in two markers that indicate improved disease recovery.

Depression and anxiety in patients with multiple sclerosis treated with interferon-beta or fingolimod: Role of indoleamine 2,3-dioxygenase and pro-inflammatory cytokines

Depression/anxiety (D/A) occurs in up to 50% of multiple sclerosis (MS) patients. Proinflammatory cytokines induce classical symptoms of depression. Activation of the inflammatory response also triggers production of indoleamine 2,3-dioxygenase (IDO), which catabolizes tryptophan, the amino acid precursor of serotonin and melatonin. It has been suggested that IDO is the link between the immune and serotonergic systems. This study aimed to quantify the levels of IDO and pro-inflammatory and anti-inflammatory cytokines in patients with MS and depression, according to treatment with interferon-beta (IFN-β) or fingolimod. The study inclusion criteria were age 18-60 years and a clinical and radiological diagnosis of MS. One hundred and thirty-two patients diagnosed by McDonald's criteria and followed up at Brasília District Hospital, Brazil, with relapsing-remitting MS were identified as potential study participants. Thirty-five of these patients were identified to be receiving treatment with fingolimod or IFN-β and to have a diagnosis of D/A. IDO and pro-inflammatory and anti-inflammatory cytokine levels were compared between these 35 patients and 18 healthy controls. The level of IL-10 (an anti-inflammatory cytokine) was lower in both the fingolimod-treated (P ​< ​0.001) and IFN-β-treated (P ​< ​0.01) patient groups than in the control group. IFN-β-treated patients showed increased IDO expression and decreased inflammatory cytokine levels. In contrast, fingolimod-treated patients showed significantly decreased expression of IDO and significantly increased levels of proinflammatory cytokines produced by innate immune cells, including tumor necrosis factor-alpha and interleukin-6. The agents used to treat MS maintain symptoms of D/A in patients with MS via different mechanisms.

Elevated Glucose Levels Favor SARS-CoV-2 Infection and Monocyte Response through a HIF-1α/Glycolysis-Dependent Axis

COVID-19 can result in severe lung injury. It remained to be determined why diabetic individuals with uncontrolled glucose levels are more prone to develop the severe form of COVID-19. The molecular mechanism underlying SARS-CoV-2 infection and what determines the onset of the cytokine storm found in severe COVID-19 patients are unknown. Monocytes and macrophages are the most enriched immune cell types in the lungs of COVID-19 patients and appear to have a central role in the pathogenicity of the disease. These cells adapt their metabolism upon infection and become highly glycolytic, which facilitates SARS-CoV-2 replication. The infection triggers mitochondrial ROS production, which induces stabilization of hypoxia-inducible factor-1α (HIF-1α) and consequently promotes glycolysis. HIF-1α-induced changes in monocyte metabolism by SARS-CoV-2 infection directly inhibit T cell response and reduce epithelial cell survival. Targeting HIF-1ɑ may have great therapeutic potential for the development of novel drugs to treat COVID-19.

Neuroinflammation at single cell level: What is new?

Multiple sclerosis is a chronic and demyelinating disease of the central nervous system (CNS), most prevalent in women, and with an important social and economic cost worldwide. It is triggered by self-reacting lymphocytes that infiltrate the CNS and initiate neuroinflammation. Further, axonal loss and neuronal death takes place, leading to neurodegeneration and brain atrophy. The murine model for studying MS, experimental autoimmune encephalomyelitis (EAE), consists in immunizing mice with myelin-derived epitopes. APCs activate encephalitogenic T CD4 and CD8 lymphocytes that migrate mainly to the spinal cord resulting in neuroinflammation. Most of the knowledge on the pathophysiology and treatment of MS was obtained from EAE experiments, as Th17 cells, anti-alpha4 blocking Abs and the role of microbiota. Conversely, recent technology breakthroughs, such as CyTOF and single-cell RNA-seq, promise to revolutionize our understanding on the mechanisms involved both in MS and EAE. In fact, the importance of specific cellular populations and key molecules in MS/EAE is a constant matter of debate. It is well accepted that both Th1 and Th17 T CD4 lymphocytes play a relevant role in disease initiation after re-activation in situ. What is still under constant investigation, however, is the plasticity of the lymphocyte population, and the individual contribution of both resident and inflammatory cells for the progression or recovery of the disease. Thus, in this review, new findings obtained after single-cell analysis of blood and central nervous system infiltrating cells from MS/EAE and how they have contributed to a better knowledge on the cellular and molecular mechanisms of neuroinflammation are discussed.

Partial remission in Brazilian children and adolescents with type 1 diabetes. Association with a haplotype of class II human leukocyte antigen and synthesis of autoantibodies

OBJECTIVE

Characterization of partial remission using the insulin dose-adjusted HbA1c (IDAA1c) ≤ 9 definition in a multiethnic Brazilian population of children and adolescents with type 1 diabetes (T1D), in addition with the determination of both Class II HLA genotype and autoantibodies.

METHODS

We analyzed the prevalence of partial remission in 51 new-onset T1D patients with a median time follow-up of 13 months from diagnosis. For this study, anti-GAD65, anti-IA2 and HLA class II genotyping were considered.

RESULTS

Partial remission occurred in 41.2% of T1D patients until 3 months after diagnosis, mainly in those aged 5-15 years. We have demonstrated a significant increase in the haplotypes of class II HLA DRB1*0301-DQB1*0201 in children and adolescents with a partial remission phase of the disease (42.9% vs 21.7% in non-remitters, P = .0291). This haplotype was also associated with the reduction of anti-IA2 antibodies production. Homozygote DRB1*03-DQB1*0201/DRB1*03-DQB1*0201 children had the lowest prevalence of IA-2A antibodies (P = .0402). However, this association does not correlate with the time of the remission phase.

CONCLUSION

Although the number of patients studied was reduced, our data suggested that the association between genetics and decrease in antibody production to certain islet auto-antigen may contribute, at least in part, to the remission phase of T1D.

Clinical and MRI correlates of CSF neurofilament light chain levels in relapsing and progressive MS

BACKGOUND

A major aim in MS field has been the search for biomarkers that enable accurate detection of neuronal damage. Besides MRI, recent studies have shown that neuroaxonal damage can also be tracked by neurofilament detection. Nevertheless, before widespread implementation, a better understanding of the principal contributors for this biomarker is of paramount importance. Therefore, we analyzed neurofilament light chain (NfL) in relapsing (RMS) and progressive MS (PMS), addressing which MRI and clinical variables are better related to this biomarker.

METHODS

Forty-seven MS patients underwent MRI (3T) and cerebrospinal fluid (CSF) sampling. We measured NfL concentrations using ELISA (UmanDiagnostics) and performed multivariable regression analysis to assess the contribution of clinical and MRI metrics to NfL.

RESULTS

NfL correlated with previous clinical activity in RMS (p < 0.001). In RMS, NfL also correlated with Gad+ and cortical lesion volumes. However, after multivariable analysis, only cortical lesions and relapses in previous 12 months remained in the final model (R² = 0.610; p = 0.009 and p = 0.00008, respectively). In PMS, T1-hypointense lesion volume was the only predictor after multivariate analysis (R² = 0.564; p = 0.012).

CONCLUSIONS

CSF NfL levels are increased in RMS and associated with relapses and cortical lesions. Although NfL levels were correlated with Gad+ lesion volume, this association did not persist in multivariable analysis after controlling for previous clinical activity. We encourage controlling for previous clinical activity when testing the association of NfL with MRI. In PMS, the major contributor to NfL was T1-hypointense lesion volume.

Inhibition of hypoxia-associated response and kynurenine production in response to hyperbaric oxygen as mechanisms involved in protection against experimental cerebral malaria

Cerebral malaria (CM) is a multifactorial syndrome involving an exacerbated proinflammatory status, endothelial cell activation, coagulopathy, hypoxia, and accumulation of leukocytes and parasites in the brain microvasculature. Despite significant improvements in malaria control, 15% of mortality is still observed in CM cases, and 25% of survivors develop neurologic sequelae for life-even after appropriate antimalarial therapy. A treatment that ameliorates CM clinical signs, resulting in complete healing, is urgently needed. Previously, we showed a hyperbaric oxygen (HBO)-protective effect against experimental CM. Here, we provide molecular evidence that HBO targets brain endothelial cells by decreasing their activation and inhibits parasite and leukocyte accumulation, thus improving cerebral microcirculatory blood flow. HBO treatment increased the expression of aryl hydrocarbon receptor over hypoxia-inducible factor 1-α (HIF-1α), an oxygen-sensitive cytosolic receptor, along with decreased indoleamine 2,3-dioxygenase 1 expression and kynurenine levels. Moreover, ablation of HIF-1α expression in endothelial cells in mice conferred protection against CM and improved survival. We propose that HBO should be pursued as an adjunctive therapy in CM patients to prolong survival and diminish deleterious proinflammatory reaction. Furthermore, our data support the use of HBO in therapeutic strategies to improve outcomes of non-CM disorders affecting the brain.-Bastos, M. F., Kayano, A. C. A. V., Silva-Filho, J. L., Dos-Santos, J. C. K., Judice, C., Blanco, Y. C., Shryock, N., Sercundes, M. K., Ortolan, L. S., Francelin, C., Leite, J. A., Oliveira, R., Elias, R. M., Câmara, N. O. S., Lopes, S. C. P., Albrecht, L., Farias, A. S., Vicente, C. P., Werneck, C. C., Giorgio, S., Verinaud, L., Epiphanio, S., Marinho, C. R. F., Lalwani, P., Amino, R., Aliberti, J., Costa, F. T. M. Inhibition of hypoxia-associated response and kynurenine production in response to hyperbaric oxygen as mechanisms involved in protection against experimental cerebral malaria.

Antimelanoma effect of Salmonella Typhimurium integration host factor mutant in murine model

AIM

This study aimed to evaluate an attenuated Salmonella ihfA-null mutant strain as therapeutic agent to control tumor growth.

MATERIALS & METHODS

After bacterial toxicity evaluation, C57BL/6JUnib mice were inoculated with B16F10 cells and treated with two Salmonella strains (LGBM 1.1 and LGBM 1.41).

RESULTS

LGBM 1.1 can reduce tumor mass, but it exerts some toxic effects. Although LGBM 1.41 is less toxic than LGBM 1.1, it does not reduce tumor mass significantly. Indeed, animals treated with LGBM 1.41 present only slightly initial delay in tumor progression and increased survival rate as compared with the control.

CONCLUSION

The null-mutants of ihfA gene of Salmonella Typhimurium could be a promising candidate for melanoma treatment.

Neuroprotection and immunomodulation by xenografted human mesenchymal stem cells following spinal cord ventral root avulsion

The present study investigates the effects of xenotransplantation of Adipose Tissue Mesenchymal Stem Cells (AT-MSCs) in animals after ventral root avulsion. AT-MSC has similar characteristics to bone marrow mesenchymal stem cells (BM-MSCs), such as immunomodulatory properties and expression of neurotrophic factors. In this study, Lewis rats were submitted to surgery for unilateral avulsion of the lumbar ventral roots and received 5 × 10(5) AT-MSCs via the lateral funiculus. Two weeks after cell administration, the animals were sacrificed and the moto neurons, T lymphocytes and cell defense nervous system were analyzed. An increased neuronal survival and partial preservation of synaptophysin-positive nerve terminals, related to GDNF and BDNF expression of AT-MSCs, and reduction of pro-inflammatory reaction were observed. In conclusion, AT-MSCs prevent second phase neuronal injury, since they suppressed lymphocyte, astroglia and microglia effects, which finally contributed to rat motor-neuron survival and synaptic stability of the lesioned motor-neuron. Moreover, the survival of the injected AT- MSCs lasted for at least 14 days. These results indicate that neuronal survival after lesion, followed by mesenchymal stem cell (MSC) administration, might occur through cytokine release and immunomodulation, thus suggesting that AT-MSCs are promising cells for the therapy of neuronal lesions.

Deciphering the biochemistry and identifying biomarkers to multiple sclerosis

Multiple sclerosis is an idiopathic demyelinating disease of the CNS. Despite being extensively studied during the last decades, many molecular aspects of the disease are still to be elucidated. Moreover, biomarkers for treatment and early diagnosis are major issues to be tackled. In this edition of Kroksveen et al. (Proteomics 2015, 15, 3361-3369) present biomarker candidates for the early detection of multiple sclerosis. Despite the need for validation in larger sets of samples, this dataset contributes to resolve open questions associated to multiple sclerosis.

Ten years of proteomics in multiple sclerosis

Multiple sclerosis, which is the most common cause of chronic neurological disability in young adults, is an inflammatory, demyelinating, and neurodegenerative disease of the CNS, which leads to the formation of multiple foci of demyelinated lesions in the white matter. The diagnosis is based currently on magnetic resonance image and evidence of dissemination in time and space. However, this could be facilitated if biomarkers were available to rule out other disorders with similar symptoms as well as to avoid cerebrospinal fluid analysis, which requires an invasive collection. Additionally, the molecular mechanisms of the disease are not completely elucidated, especially those related to the neurodegenerative aspects of the disease. The identification of biomarker candidates and molecular mechanisms of multiple sclerosis may be approached by proteomics. In the last 10 years, proteomic techniques have been applied in different biological samples (CNS tissue, cerebrospinal fluid, and blood) from multiple sclerosis patients and in its experimental model. In this review, we summarize these data, presenting their value to the current knowledge of the disease mechanisms, as well as their importance in identifying biomarkers or treatment targets.

Structural brain abnormalities are related to retinal nerve fiber layer thinning and disease duration in neuromyelitis optica spectrum disorders

BACKGROUND

Although aquaporin-4 (AQP4) is widely expressed in the human brain cortex, lesions are rare in neuromyelitis optica (NMO) spectrum disorders (NMOSD). Recently, however, several studies have demonstrated occult structural brain atrophy in NMO.

OBJECTIVE

This study aims to investigate magnetic resonance imaging (MRI) patterns of gray matter (GM) and white matter (WM) abnormalities in patients with NMOSD and to assess the visual pathway integrity during disease duration correlation of the retinal nerve fiber layer (RNFL) and pericalcarine cortex thickness.

METHODS

Twenty-one patients with NMOSD and 34 matched healthy controls underwent both high-field MRI (3T) high-resolution T1-weighted and diffusion-tensor MRI. Voxel-based morphometry, cortical analyses (Freesurfer) and diffusion-tensor imaging (DTI) analyses (TBSS-FSL) were used to investigate brain abnormalities. In addition, RNFL measurement by optic-coherence tomography (OCT) was performed.

RESULTS

We demonstrate that NMOSD is associated with GM and WM atrophy, encompassing more frequently the motor, sensory and visual pathways, and that the extent of GM atrophy correlates with disease duration. Furthermore, we demonstrate for the first time a correlation between RNFL and pericalcarine cortical thickness, with cortical atrophy evolving over the course of disease.

CONCLUSIONS

Our findings indicate a role for retrograde and anterograde neurodegeneration in GM atrophy in NMOSD. However, the presence atrophy encompassing almost all lobes suggests that additional pathomechanisms might also be involved.

Vitamin D3 induces IDO+ tolerogenic DCs and enhances Treg, reducing the severity of EAE

BACKGROUND

A growing body of evidence supports the hypothesis that vitamin D is an important environmental factor in the etiology of T-cell-mediated autoimmune diseases such as multiple sclerosis (MS).

AIM

The purpose of this study was exploring the mechanisms underlying the beneficial effect of vitamin D3 in encephalomyelitis (EAE).

METHODS

We treated monophasic experimental autoimmune EAE, induced in Lewis rat, with vitamin D3 and adoptively transfer tolerogenic bone marrow-derived DCs generated in the presence of vitamin D3.

RESULTS

This study provides evidence that the in vivo administration of vitamin D3, as well as the adoptive transfer of vitamin D3 -induced IDO(+) immature/tolerogenic dendritic cells, leads to a significant increase in the percentage of CD4(+) CD25(+) Foxp3(+) regulatory T cells in the lymph nodes in a rat model of MS, experimental autoimmune EAE. Concomitant with the increase in this cell population, there is a significant decrease in the number of autoreactive T cells in the central nervous system. Bone marrow-derived DCs cultivated in the presence of vitamin D3 present a tolerogenic profile with high IL-10, TNFα, and IDO expression and decreased MHC-II and CD80 expression. The adoptive transfer of IDO (+) DCs induces a significant increase in the percentage of CD4(+) CD25(+) Foxp3(+) T cells in the lymph nodes, comparable with vitamin D3 treatment.

CONCLUSION

These mechanisms contribute actively to the generation of a microenvironment in the lymph nodes that suppresses the activation of encephalitogenic T cells, resulting in the downregulation of the inflammatory response in the central nervous system.

The suppressive effect of IL-27 on encephalitogenic Th17 cells induced by multiwalled carbon nanotubes reduces the severity of experimental autoimmune encephalomyelitis

BACKGROUND

Both Th1 and Th17 cells specific for neuroantigen are described as encephalitogenic in the experimental autoimmune encephalomyelitis (EAE) model.

AIM

The proposal of this study was to investigate how carbon nanotubes internalized by antigen-presenting cells (APCs) affect the development of encephalitogenic CD4(+) T cells.

METHODS

Therefore, we stimulated encephalitogenic T cells in the presence or not of multiwalled carbon nanotube (MWCNT). After the incubation, we analyzed the expression profile of the encephalitogenic T cells and their capacity to induce EAE.

RESULTS

Encephalitogenic CD4(+) T cells cultured with APCs that were previously incubated with MWCNTs do not express IL-17. The adoptive transfer of these cells causes less severe EAE than the transfer of both Th1 and Th17 cells that are not incubated with MWCNTs. These results suggest that the increased IL-27 level produced by the APCs incubated with the carbon nanotubes inhibits the development of Th17 cells. This observation is confirmed by the concomitant reduction in the level of RORγt, which is a transcription factor essential for the development of Th17 cells. Moreover, the incubation of encephalitogenic T cells devoid of Th17 cells with neutralizing anti-IL-27 antibodies restored the production of IL-17.

CONCLUSION

This finding confirms the suppressive effect of IL-27 on encephalitogenic Th17 cells. The results presented suggest that the stimulation of APCs with carbon nanoparticles prior to neuroantigen presentation affects the development of the Th17 subset of encephalitogenic CD4(+) T lymphocytes and results in less severe EAE.

Proteome analysis of spinal cord during the clinical course of monophasic experimental autoimmune encephalomyelitis

The induction of autoimmune encephalomyelitis (EAE) in Lewis rats results in a period of exacerbation followed by complete recovery. Therefore, this model is widely used for studying the evolution of multiple sclerosis. In the present investigation, differentially expressed proteins in the spinal cord of Lewis rats during the evolution of EAE were assessed using the combination of 2DE and MALDI-TOF MS. The majority of the differentially expressed proteins were identified during the acute phase of EAE, in relation to naïve control animals. On the other hand, recovered rats presented a similar protein expression pattern in comparison with the naïve ones. This observation can be explained, at least in part, by the intense catabolism existent in acute phase due to nervous tissue damage. In recovered rats, we have described the upregulation of proteins that are apparently involved in the recovery of damaged tissue, such as light and medium neurofilaments, glial fibrillary acidic protein, tubulins subunits, and quaking protein. These proteins are involved mainly in cell growth, myelination, and remyelination as well as in astrocyte and oligodendrocyte maturation. The present study has demonstrated that the inflammatory response, characterized by an increase of the proliferative response and infiltration of autoreactive T lymphocytes in the central nervous system, occurs simultaneously with neurodegeneration.

Cellulitis lesions in broiler chickens are induced by Escherichia coli Vacuolating Factor (ECVF)

Escherichia coli Vacuolating Factor (ECVF) is a heat-labile, vacuolating cytotoxin produced by avian pathogenic E. coli (APEC) isolated from avian cellulitis lesions. In this report, we intend to demonstrate that purified ECVF induces the inflammatory process of cellulitis. Our group is the first to demonstrate the effect of ECVF in a histological analysis by in situ inoculation of broiler chickens with purified ECVF. The animals were inoculated with the APEC AC53 and with purified ECVF subcutaneously on their ventral surface (in the sternum region). The histological analysis showed different grades of an acute inflammatory response in the epidermis, dermis and panniculus. An increase in mRNA expression of the proinflammatory cytokine TNF-α was also demonstrated in the inflamed tissue. When ECVF was systemically administered, increased levels of TNF-α and IL-10 were observed in the serum. These results suggest that ECVF plays a key role in the inflammatory process associated with cellulitis that is mainly mediated by TNF-α. In addition, this inflammation can be downregulated by the anti-inflammatory cytokine IL-10.

Aquaporin-4 antibodies are not related to HTLV-1 associated myelopathy

Introduction

The seroprevalence of human T-cell leukemia virus type 1 (HTLV-1) is very high among Brazilians (∼1∶200). HTLV-1 associated myelopathy or tropical spastic paraparesis (HAM/TSP) is the most common neurological complication of HTLV-1 infection. HAM/TSP can present with an acute/subacute form of longitudinally extensive myelitis, which can be confused with lesions seen in aquaporin-4 antibody (AQP4-Ab) positive neuromyelitis optica spectrum disorders (NMOSD) on MRI. Moreover, clinical attacks in patients with NMOSD have been shown to be preceded by viral infections in around 30% of cases.

Objective

To evaluate the frequency of AQP4-Ab in patients with HAM/TSP. To evaluate the frequency of HTLV-1 infection in patients with NMOSD.

Patients and Methods

23 Brazilian patients with HAM/TSP, 20 asymptomatic HTLV-1+ serostatus patients, and 34 with NMOSD were tested for AQP4-Ab using a standardized recombinant cell based assay. In addition, all patients were tested for HTLV-1 by ELISA and Western blotting.

Results

20/34 NMOSD patients were positive for AQP4-Ab but none of the HAM/TSP patients and none of the asymptomatic HTLV-1 infected individuals. Conversely, all AQP4-Ab-positive NMOSD patients were negative for HTLV-1 antibodies. One patient with HAM/TSP developed optic neuritis in addition to subacute LETM; this patient was AQP4-Ab negative as well. Patients were found to be predominantly female and of African descent both in the NMOSD and in the HAM/TSP group; Osame scale and expanded disability status scale scores did not differ significantly between the two groups.

Conclusions

Our results argue both against a role of antibodies to AQP4 in the pathogenesis of HAM/TSP and against an association between HTLV-1 infection and the development of AQP4-Ab. Moreover, the absence of HTLV-1 in all patients with NMOSD suggests that HTLV-1 is not a common trigger of acute attacks in patients with AQP4-Ab positive NMOSD in populations with high HTLV-1 seroprevalence.

Quantitative MRI and cerebrospinal fluid inflammatory mediators in Brazilian patients with relapsing-remitting multiple sclerosis before and after treatment with immunomodulators: a longitudinal study

OBJECTIVE

The pathological hallmarks of multiple sclerosis (MS) lesions are inflammation, demyelination, axon loss and gliosis. The aim of this study was to verify the relation of brain lesion load and volume of the cerebral hemisphere determined by brain MRI with intrathecal antibody synthesis.

METHODS

A longitudinal study of 54 Brazilian patients with the relapsing-remitting form of MS was undertaken after an average of 6.3 ± 2.7 years of treatment. MRI scans were performed, and cerebrospinal fluid samples were collected both during the diagnostic process and after treatment with β-interferon or glatiramer acetate.

RESULTS

A positive correlation between the IgG index and total lesion volume was identified. Intrathecal IgG against Epstein-Barr virus (EBV) was observed in 21 patients. The number of contrast-enhanced lesions observed in these patients was correlated with intrathecal IgM synthesis. Brain atrophy was observed early in the disease, with the number of relapses inversely correlated with brain volume.

CONCLUSION

The high intrathecal IgG synthesis observed in these relapsing-remitting MS patients is associated with the brain lesion burden and the presence of antibodies to EBV, whereas intrathecal IgM synthesis is associated with the activity of the disease, as revealed by MRI.

Disappearance of cerebrospinal fluid oligoclonal bands after natalizumab treatment of multiple sclerosis patients

Intrathecal immunoglobulin synthesis in an oligoclonal pattern is the most common immunologic abnormality detected in MS patients. Various treatments, such as immunomodulators and immunosuppressors, have not been found to modify it. Natalizumab hinders migration of encephalitogenic T-cells into the central nervous system (CNS), reducing inflammatory response. Its impact on CSF oligoclonal bands (OCBs) has not been demonstrated. This report describes its effect in four out of six patients with multiple sclerosis after a mean of 10 infusions: the CSF was negative for OCBs at the second lumbar puncture. In conclusion, natalizumab treatment can reduce CSF OCBs to undetectable levels, although the clinical significance of this observation is not yet known.

Up-regulation of T lymphocyte and antibody production by inflammatory cytokines released by macrophage exposure to multi-walled carbon nanotubes

Our data demonstrate that multi-walled carbon nanotubes (MWCNTs) are internalized by macrophages, subsequently activating them to produce interleukin (IL)-12 (IL-12). This cytokine induced the proliferative response of T lymphocytes to a nonspecific mitogen and to ovalbumin (OVA). This increase in the proliferative response was accompanied by an increase in the expression of pro-inflammatory cytokines, such as interferon-gamma (IFNγ), tumor necrosis factor-alpha (TNFα) and IL-6, in mice inoculated with MWCNTs, whether or not they had been immunized with OVA. A decrease in the expression of transforming growth factor-beta (TGFβ) was observed in the mice treated with MWCNTs, whereas the suppression of the expression of both TGFβ and IL-10 was observed in mice that had been both treated and immunized. The activation of the T lymphocyte response by the pro-inflammatory cytokines leads to an increase in antibody production to OVA, suggesting the important immunostimulatory effect of carbon nanotubes.

Regulatory T cell induction during Plasmodium chabaudi infection modifies the clinical course of experimental autoimmune encephalomyelitis

Background

Experimental autoimmune encephalomyelitis (EAE) is used as an animal model for human multiple sclerosis (MS), which is an inflammatory demyelinating autoimmune disease of the central nervous system characterized by activation of Th1 and/or Th17 cells. Human autoimmune diseases can be either exacerbated or suppressed by infectious agents. Recent studies have shown that regulatory T cells play a crucial role in the escape mechanism of Plasmodium spp. both in humans and in experimental models. These cells suppress the Th1 response against the parasite and prevent its elimination. Regulatory T cells have been largely associated with protection or amelioration in several autoimmune diseases, mainly by their capacity to suppress proinflammatory response.

Methodology/Principal Findings

In this study, we verified that CD4⁺CD25⁺ regulatory T cells (T regs) generated during malaria infection (6 days after EAE induction) interfere with the evolution of EAE. We observed a positive correlation between the reduction of EAE clinical symptoms and an increase of parasitemia levels. Suppression of the disease was also accompanied by a decrease in the expression of IL-17 and IFN-γ and increases in the expression of IL-10 and TGF-β1 relative to EAE control mice. The adoptive transfer of CD4⁺CD25⁺ cells from P. chabaudi-infected mice reduced the clinical evolution of EAE, confirming the role of these T regs.

Conclusions/Significance

These data corroborate previous findings showing that infections interfere with the prevalence and evolution of autoimmune diseases by inducing regulatory T cells, which regulate EAE in an apparently non-specific manner.

Interferon-beta modifies the peripheral blood cell cytokine secretion in patients with multiple sclerosis

Immunotherapy with Interferon-beta (IFNbeta) results in remarkably beneficial effects in patients with relapsing-remitting multiple sclerosis (MS), although the mechanisms by which it exerts these beneficial effects remain poorly understood. An investigation was made of the effects of IFNbeta on pro-inflammatory and anti-inflammatory cytokine production in peripheral blood cells in MS patients, both untreated and those undergoing immunotherapy, as well as in healthy controls. Results show a significant increase in the production of pro-inflammatory cytokines such as TNFalpha, IFNgamma and IL-12 in the plasma and in the supernatant of leukocyte cultures from MS patients with the untreated disease; IFNbeta administration significantly reduced the levels of TNFalpha and IFNgamma, with no changes in the level of IL-12. The Interferon-beta therapy also led to a significant increase in the production of IL-10, as well as a slight increase in that of TGFbeta. The reduction in pro-inflammatory cytokine production in the treated MS patient group, accompanied by a simultaneous increase in the production of anti-inflammatory cytokines and the reduction of relapse rates suggests that the beneficial effects of IFNbeta immunotherapy result, at least in part, from the modulation of cytokine patterns.

Neuropathy of gastrointestinal Chagas' disease: immune response to myelin antigens

Most reports of autoimmune response during infection with the parasite Trypanosoma cruzi have dealt with the cardiomyopathic form of Chagas' disease, but little is known about the mechanisms of tissue damage involved in the gastrointestinal form, which was studied here. Chronically infected patients with a severe gastrointestinal form of Chagas' disease present increased antibody production and proliferative responses to peripheral myelin components, such as myelin basic protein (MBP), which is homologous to the P1 protein fraction of peripheral myelin. T lymphocytes preferentially recognize a region on the MBP molecule (1-30), which suggests that the MBP is a potential target on the peripheral nerve for autoimmune reactions in patients with gastrointestinal lesions resulting from Chagas' disease.

Hyperbaric oxygen prevents early death caused by experimental cerebral malaria

Background

Cerebral malaria (CM) is a syndrome characterized by neurological signs, seizures and coma. Despite the fact that CM presents similarities with cerebral stroke, few studies have focused on new supportive therapies for the disease. Hyperbaric oxygen (HBO) therapy has been successfully used in patients with numerous brain disorders such as stroke, migraine and atherosclerosis.

Methodology/Principal Findings

C57BL/6 mice infected with Plasmodium berghei ANKA (PbA) were exposed to daily doses of HBO (100% O₂, 3.0 ATA, 1–2 h per day) in conditions well-tolerated by humans and animals, before or after parasite establishment. Cumulative survival analyses demonstrated that HBO therapy protected 50% of PbA-infected mice and delayed CM-specific neurological signs when administrated after patent parasitemia. Pressurized oxygen therapy reduced peripheral parasitemia, expression of TNF-α, IFN-γ and IL-10 mRNA levels and percentage of γδ and αβ CD4⁺ and CD8⁺ T lymphocytes sequestered in mice brains, thus resulting in a reduction of blood-brain barrier (BBB) dysfunction and hypothermia.

Conclusions/Significance

The data presented here is the first indication that HBO treatment could be used as supportive therapy, perhaps in association with neuroprotective drugs, to prevent CM clinical outcomes, including death.

Diminished myelin-specific T cell activation associated with increase in CTLA4 and Fas molecules in multiple sclerosis patients treated with IFN-beta

Multiple sclerosis (MS) is a chronic inflammatory disease of the white matter of the central nervous system (CNS) characterized by focal areas of demyelination. Interferon-beta (IFN-beta) provides an effective treatment that lessens the frequency and severity of exacerbations in relapsing-remitting multiple sclerosis (RRMS), but the mechanisms by which IFN-beta is efficient remain uncertain. The data presented here demonstrate that IFN-beta impairs the proliferative response to myelin basic protein (MBP) and myelin, as well as increasing the expression of the CTLA4 intracellular molecule. Moreover, this treatment increases the expression of surface Fas molecules and of the soluble form of these molecules. Our hypothesis is that the increase in Fas and CTLA4 molecules in MS patients may lead to lymphocyte apoptosis, which suggests possible mechanisms underlying the therapeutic response to IFN-beta.

Nitric oxide and TNFalpha effects in experimental autoimmune encephalomyelitis demyelination

The involvement of inducible nitric oxide synthase (iNOS), which plays various roles in the progression of autoimmune diseases, was studied in iNOS knockout (KO) mice and wild-type (WT) controls with respect to experimental autoimmune encephalomyelitis (EAE). The iNOS (KO) mice presented a less severe form of the disease than the WT control mice. Although the levels of TNFalpha decreased in the periphery in both groups, an increase in the number of TNFalpha-positive cells was detected in the central nervous system during the acute phase of EAE in the WT mice, but not in the KO mice. These findings suggest that NO and TNFalpha contribute to the pathogenesis of acute EAE.

The effect of treatment with crotapotin on the evolution of experimental autoimmune neuritis induced in Lewis rats

Biomedical research in which venom components are being investigated for their potential as novel therapeutic agents has emerged as an interesting option. Crotapotin, which is purified from the venom of the rattlesnake Crotalus durissus terrificus, has been described as an anti-inflammatory agent that acts on the innate arm of the immune response. Here we have demonstrated that intraperitoneal administration of crotapotin significantly reduces the severity of experimental autoimmune neuritis (EAN), an experimental model for Guillain-Barré syndrome. The reduction of the severity of the disease is associated with a reduction in the mononuclear cells infiltrating the sciatic nerve and a significant decrease in the lymphocyte proliferative response to neuritogenic peptide.

Intrathecal immunoglobulin G synthesis and brain injury by quantitative MRI in multiple sclerosis

OBJECTIVES

It was the aim of this study to evaluate if the quantitative intrathecal immunoglobulin G (IgG) synthesis correlates with the brain atrophy and the total lesion volume (TLV) in brain magnetic resonance imaging (MRI) of multiple sclerosis (MS) patients.

METHODS

A total of 50 patients with relapsing-remitting MS were included in this study. MRIs were performed and cerebrospinal fluid samples were collected during the diagnostic determination when patients were in remission without treatment.

RESULTS

At study baseline, IgG index values were elevated in 36 patients (72%), and oligoclonal IgG bands were positive in 42 of 50 patients (84%). Brain MRI was abnormal in 94% of patients, and, compared with healthy controls, brain atrophy was observed in MS patients. A positive correlation among IgG index, cerebrospinal fluid leukocyte count and TLV was observed; the Expanded Disability Status Scale correlated positively with TLV and the number of lesions, although a significant relationship between disability and brain atrophy was not demonstrated.

CONCLUSIONS

Although new parameters will be necessary in longitudinal studies to characterize the axonal injury in various stages of the disease, the data suggest that the high intrathecal IgG synthesis may predict a greater brain lesion burden.

Costimulatory molecule expression on leukocytes from mice with experimental autoimmune encephalomyelitis treated with IFN-beta

Interferon-beta (IFN-beta) is of benefit in the treatment of multiple sclerosis (MS) and experimental autoimmune encephalomyelitis (EAE), but the mechanisms by which it exerts this beneficial effect remain uncertain. The present data demonstrate that IFN-beta therapy impairs the proliferative response to concanavalin A (ConA) and myelin basic protein (MBP), decreases expression of the CD80 molecule on leukocytes of treated mice, and may thereby impede the Th1 cell activation-promoting anergy in EAE. Moreover, IFN-beta therapy increases expression of the CTLA4 molecule, which induces a counterregulatory Th2 response. The reduction of CD80 expression with concomitant increase of CTLA4 expression alters the course of EAE and may be useful as a monitor in therapy with IFN-beta.