Immunoglobulin G Fc N-glycosylation in Guillain-Barré syndrome treated with intravenous immunoglobulin.

Intravenous immunoglobulin (IVIg) is the treatment of choice for Guillain-Barré syndrome (GBS), an immune-mediated peripheral neuropathy causing rapidly progressive limb weakness and respiratory failure. The working mechanism of IVIg in autoimmune diseases has not been elucidated, but previous studies indicate that some anti-inflammatory effects may be mediated by the N-glycosylation of the Fc-portion of IgG. GBS is a model disease to investigate these effects because GBS is an acute and monophasic disorder usually affecting healthy persons, which is treated with a standard course of IVIg, although the clinical response is highly variable. In the current study, the N-glycosylation of the Fc-portion of serum IgG was investigated in patients with GBS before and after treatment with IVIg in relation to clinical course and outcome. Glycoforms of serum IgG1 and IgG2 were determined separately by liquid chromatography mass spectrometry. These IgG subclasses were purified from the serum of 174 GBS patients before and in 150 patients 2 weeks after standard IVIg treatment regimen. Treatment-naive GBS patients compared with age- and sex-matched controls had lower levels of galactosylation of IgG1 and IgG2. IVIg preparations contained relatively high levels of galactosylated and sialylated IgG Fc glycoforms compared with serum IgG in patients. Treatment with IVIg resulted in an increase in serum of the Fc-galactosylation and -sialylation of both IgG1 and IgG2. The extent of normalization in serum IgG Fc glycosylation varied between patients. Multiple logistic regression analysis showed that patients with persistent low IgG galactosylation and sialylation despite IVIg treatment had the most severe forms of GBS and needed ventilator support more often. Kaplan-Meier analysis showed that these patients also needed more time to be able to walk again compared with patients with a normalized IgG Fc glycosylation profile. In conclusion, our results suggest that serum IgG Fc glycosylation in GBS is related to disease severity and clinical recovery after IVIg and may help to develop new measures to monitor the efficacy of treatment.

Introduction IgG4-related disease (IgG4-RD) is a systemic fibro-inflammatory condition characterised by an abundance of IgG4+ antibodies in the serum and tissue of involved organs. IgG glycosylation plays an important role in many chronic inflammatory and autoimmune conditions. We sought to assess the glycosylation status in patients with IgG4-RD and correlate with disease activity, damage and response to treatment. Methods IgG Fc and Fab glycosylation status was assessed in patients with IgG4-RD involving the bile ducts (IgG4-sclerosing cholangitis, IgG4-SC) and pancreas (autoimmune pancreatitis) (n=22), disease controls with primary sclerosing cholangitis (DC n=22) and healthy controls (HC n=22). Disease activity, organ damage and response to treatment were assessed serially using the IgG4-responder index. Serum IgG and subclasses were quantified using an ELISA and nephelometry. IgG and subclass Fc glycosylation was analysed by mass spectrometry and Fab glycosylation by lectin (SNA) affinity chromatography. Statistics were performed using Prism. Results IgG4-SC and AIP patients exhibited reduced total IgG Fc galactosylation and IgG1 Fc bisection, and increased IgG4 Fc fucosylation and IgG2/3 Fc hybrid compared with HC. There was recovery of IgG1 Fc bisection (increase) and IgG2/3 Fc hybrid (decrease) upon corticosteroid treatment. IgG Fc galactosylation and IgG2/3 Fc hybrid correlated with disease activity. IgG Fab glycosylation was higher in IgG4-RD patients, with an increase in IgG4-specific, and to a lesser extent IgG1-specific, Fab glycosylation compared to HC and DC. Conclusions In the first study to assess glycosylation status in IgG4-RD, we demonstrated alterations in both IgG Fc and Fab glycosylation, which may play a role in pathophysiology and serve as a biomarker of disease.

The IVIg Dilemma: A Way Out?

Human IgG Fc-glycosylation profiling reveals associations with age, sex, female sex hormones and thyroid cancer

BackgroundGuillain‐Barré syndrome is an acute, paralysing, inflammatory peripheral nerve disease. Intravenous immunoglobulin is beneficial in other autoimmune diseases.ObjectivesWe aimed to determine the efficacy of intravenous immunoglobulin for Guillain‐Barré syndrome.Search strategyWe updated the searches of the Cochrane Neuromuscular Disease Group Trials Specialized Register, MEDLINE and EMBASE in June 2009 using the terms 'Guillain‐Barré syndrome' and 'acute polyradiculoneuritis' combined with 'intravenous immunoglobulin'.Selection criteriaWe included randomised and quasi‐randomised trials.Data collection and analysisTwo authors independently selected papers, extracted data and assessed quality.Main resultsAnother Cochrane systematic review has shown that plasma exchange significantly hastens recovery. In this review, five trials compared intravenous immunoglobulin with plasma exchange in 536 severely affected, mostly adult participants. The mean difference of change in a seven‐grade disability scale after four weeks was not significantly different between the two treatments: 0.02 (95% CI 0.25 to ‐0.20) of a grade more improvement in the intravenous immunoglobulin than the plasma exchange group. There were also no statistically significant differences in the other measures considered. Three studies including a total of 75 children suggested that intravenous immunoglobulin significantly hastens recovery compared with supportive care.In one trial involving 249 participants comparing plasma exchange followed by intravenous immunoglobulin with plasma exchange alone, the mean grade improvement was 0.2 (95% CI ‐0.14 to 0.54) more in the combined treatment group than in the plasma exchange alone group, not significantly different but not excluding the possibility of significant extra benefit. Another trial with 37 participants comparing immunoabsorption followed by intravenous immunoglobulin with immunoabsorption alone did not reveal significant extra benefit from the combined treatment.Small trials in children showed a trend towards more improvement with high‐dose compared with low‐dose intravenous immunoglobulin and no significant difference when the standard dose was given over two days rather than five days.Authors' conclusionsA previous Cochrane review has shown that plasma exchange hastens recovery compared with supportive treatment alone. There are no adequate comparisons of intravenous immunoglobulin with placebo in adults but this review provides moderate quality evidence that, in severe disease, intravenous immunoglobulin started within two weeks from onset hastens recovery as much as plasma exchange. Adverse events were not significantly more frequent with either treatment but intravenous immunoglobulin is significantly much more likely to be completed than plasma exchange. Also according to moderate quality evidence, giving intravenous immunoglobulin after plasma exchange did not confer significant extra benefit. In children, according to low quality evidence, intravenous immunoglobulin probably hastens recovery compared with supportive care alone. More research is needed in mild disease and in patients whose treatment starts more than two weeks after onset. Dose‐ranging studies are also needed.Plain Language SummaryIntravenous immunoglobulin for Guillain‐Barré syndromeGuillain‐Barré syndrome is an uncommon disease of the peripheral nerves. It causes weakness, numbness and breathing difficulty. Another Cochrane review has shown that plasma exchange (taking blood from one vein, separating the plasma from the blood cells and then returning the blood cells with a plasma substitute into another vein) is more effective than supportive care alone. In adults, moderate quality evidence shows that receiving intravenous immunoglobulin (antibodies that have been purified from donated blood) speeds recovery from severe Guillain‐Barré syndrome as much as plasma exchange. Intravenous immunoglobulin is slightly safer and much easier to give than plasma exchange. According to moderate quality evidence, intravenous immunoglobulin added to plasma exchange is not significantly more effective than either alone. A small amount of evidence suggests that intravenous immunoglobulin is also beneficial in children. More research is needed to determine the best dose in adults and children.

Acute thromboembolic events associated with intravenous immunoglobulin infusion in antibody-deficient patients

Intravenous immunoglobulin (IVIg) treatment ameliorates the course of Guillain-Barré syndrome (GBS), but its specific mode of action is unknown. We attempted to delineate the effect of IVIg on neuromuscular blocking antibodies in GBS. A total of seven GBS serum samples were examined for blocking antibodies and the effect of IVIg with a macro-patch-clamp technique in mouse hemidiaphragms. First, serum was tested before and after treatment with IVIg. Second, we investigated with coincubation experiments whether the IVIg was capable of neutralizing neuromuscular blocking antibodies in GBS serum or affinity-purified immunoglobulin G (IgG) fractions. Finally, the mechanism of the neutralizing effect was studied by the coincubation of active blocking GBS IgG with Fab and Fc fragments prepared from IVIg. All GBS sera (two adults and two children) and GBS IgG fractions (three adults) taken before treatment with IVIg blocked evoked quantal release by approximately 90%. Blocking activity was markedly reduced in sera obtained after treatment with IVIg. Coincubation of the pretreatment blocking serum with the posttreatment serum, or with the IVIg preparation used for treatment, reduced the blocking activity of the pretreatment GBS serum. When GBS IgG was coincubated with IVIg, the blocking activity of GBS IgG was diminished dose-dependently. Monovalent and divalent Fab fragments prepared from the IVIg were as effective as whole IVIg, but Fc fragments were ineffective. Therapeutic IVIg is capable of neutralizing neuromuscular blocking antibodies in GBS by a dose-dependent, antibody-mediated mechanism. This may, in part, explain its therapeutic efficacy.

Intravenous immunoglobulin significantly reduces exposure of concomitantly administered anti-C5 monoclonal antibody tesidolumab.

The interactions of antibodies with myeloid Fcγ receptors and the complement system are regulated by an Asn297-linked glycan in the Fc portion of IgG. Alterations of serum IgG-Fc glycosylation have been reported in various autoimmune diseases, and correlate with treatment response and disease activity. We hypothesized that IgG-Fc glycosylation is altered in immune thrombocytopenia (ITP) and associates with response to anti-CD20 monoclonal antibody treatment (rituximab). IgG-Fc glycosylation was analyzed by liquid chromatography-mass spectrometry. We found that IgG-Fc glycosylation was identical between refractory ITP patients (HOVON64 trial; N = 108) and healthy controls (N = 120). Two months after rituximab treatment, we observed a shift in Fc glycosylation, with a mean 1.7% reduction in galactosylation for IgG1 and IgG4 and a mean 1.5% increase for bisection in IgG1, IgG2/3 and IgG4 (adjusted p < 1.7 × 10−3 and p < 2 × 10−4, respectively). Neither baseline nor longitudinal changes in IgG-Fc glycosylation after rituximab were associated with clinical treatment response. We conclude that IgG-Fc glycosylation in refractory ITP is similar to healthy controls and does not predict treatment responses to rituximab. The observed changes two months after treatment suggest that rituximab may influence total serum IgG-Fc glycosylation. Overall, our study suggests that the pathophysiology of refractory ITP may differ from other autoimmune diseases.

Guillain-Barre syndrome (GBS) is the most common cause of acute neuromuscular paralysis, usually due to acute inflammatory demyelinating polyradiculoneuropathy. The presence of activated T lymphocytes and antibodies against peripheral nerve myelin suggests an autoimmune pathogenesis, although there is wide heterogeneity. Gangliosides are sialylated glycolipids widely distributed in nervous system membranes. GBS is usually preceded by an infection, most frequently Campylobacter jejuni enteritis, but also cytomegalovirus, Mycoplasma pneumoniae or Epstein-Barr virus. Patients with GBS and C. jejuni infection are more likely to have neurophysiological features of axonal neuropathy, antibodies to ganglioside GM1, pure motor GBS, a less elevated CSF protein concentration and a worse outcome than other GBS patients. Although molecular mimicry between peripheral nerve gangliosides and epitopes present on C. jejuni lipopolysaccharide could explain some of these associations, this hypothesis is inadequate to account for many aspects of the pathogenesis of GBS.

Glycans attached to the Fc region of IgG antibodies influence their pro- or anti-inflammatory effector function. We aimed to explore the interrelation of the Fc glycosylation profile and disease transition, disease activity, and outcome in patients with suspected and confirmed primary Sjögren disease (SjD). IgG Fc sialylation and IgG Fc galactosylation serum levels were determined in 300 patients from the Belgian Sjögren's Syndrome Transition Trial. This cohort includes both suspected and confirmed patients with SjD meeting the 2016 American College of Rheumatology/EULAR criteria. Salivary gland involvement was evaluated through ultrasonography (Hocevar score 0-48) and histopathology (focus score). The relative amount of sialylated and galactosylated IgG was determined by capillary electrophoresis after using the endoglycosidase S-based assay. Patients with SjD exhibited significantly lower sialylation and galactosylation levels versus asymptomatic carriers of anti-SSA and patients with sicca. Lower sialylation and galactosylation levels were significantly associated with an increase in B cell activation markers and distinct autoantibody profiles, particularly with multiple autoantibody reactivities. They were also linked to histopathological salivary gland alterations, higher Hocevar scores, and, importantly, risk factors for non-Hodgkin lymphoma (NHL) development. In contrast, patients with SjD who were mono-anti-Ro60 positive and those who were anti-SSA negative had normal IgG Fc glycosylation. This study points to a novel role of IgG Fc glycosylation in patients with SjD in predicting disease transition, monitoring disease activity, and stratifying risk of NHL development.

AimAntiretroviral therapy (ART) development has reduced the severity of neurological complications of the human immunodeficiency virus (HIV), but they remain prevalent and need prompt recognition. Acute inflammatory demyelinating polyneuropathy (AIDP) is a rare complication of human immunodeficiency virus (HIV) infection that may appear at any stage of the disease. In this case, AIDP represents a late presentation of HIV infection.MethodsDescriptive study. Patient data were collected from their medical records and by health assessment interviews.ResultsWe report a case of a 52-year-old male with acute lower limb weakness. Given the suggestive clinical presentation of AIDP and a positive HIV test, intravenous immunoglobulin (IVIG) was administered along with antiretroviral therapy. Progressive weakness to the upper limbs, autonomic dysfunction, and pain was observed. The second regimen of IVIG plus corticosteroids was administered. Muscle strength improved after three weeks.ConclusionsScreening for HIV in a patient with AIDP may provide a better outcome because of the early start of ART with good central nervous system penetration in HIV-infected patients.

High-dose intravenous immunoglobulin (IVIg) is effective in the treatment of idiopathic autoimmune neuropathies including Guillain-Barré syndrome (GBS), chronic inflammatory demyelinating neuropathy (CIDP) and multifocal motor neuropathy (MMN), representing a useful option or, as in MMN, the gold standard for their treatment. In GBS, two randomised, controlled trials (RCT) showed that IVIg is at least as effective as plasma exchange (PE). IVIg may however be preferred due to its low number of contraindications and complications and the fact that it can be administered at any time, in any department, including patients with contraindications to PE, or in intensive care units. In CIDP, at least four RCTs have demonstrated the efficacy of IVIg in over 60% of CIDP patients, while two additional RCTs have shown a comparable effect to steroids and PE as initial treatment. As with PE, the effects of IVIg usually last a few weeks meaning that the majority of patients require periodic maintenance infusions. The lower cost and easier administration of oral steroids compared to IVIg may be partly compensated by the safer long-term profile of IVIg over steroids. In MMN, almost 80% of patients improve with IVIg, the efficacy of which has been confirmed by four RCTs, making of IVIg the first-choice therapy in MMN, for which steroids and PE are ineffective or even detrimental. Also in these patients, IVIg induces a rapid improvement that usually lasts only a few weeks and has to be maintained with periodic IVIg infusions for long periods of time, if not indefinitely.

A crucial factor for the development of inflammatory autoimmune diseases is the occurrence of antibodies directed against self-tissues and structures, which leads to damage and inflammation. While little is known about the cause of the development of mis-directed, disease-specific T and B cells and resulting IgG autoantibody responses, there is increasing evidence that their induction can occur years before disease symptoms appear. However, a certain proportion of healthy individuals express specific IgG autoantibodies without disease symptoms and not all subjects who generate autoantibodies may develop disease symptoms. Thus, the development of inflammatory autoimmune diseases seems to involve two steps. Increasing evidence suggests that harmless self-directed T and B cell and resulting IgG autoantibody responses in the pre-autoimmune disease stage might switch to more inflammatory T and B cell and IgG autoantibody responses that trigger the inflammatory autoimmune disease stage. Here, we summarize findings on the transition from the pre-disease to the disease stage and vice versa, e.g. by pregnancy and treatment, with a focus on low-/anti-inflammatory versus pro-inflammatory IgG autoantibody responses, including IgG subclass and Fc glycosylation features. Characterization of biomarkers that identify the transition from the pre-disease to the disease stage might facilitate recognition of the ideal time point of treatment initiation and the development of therapeutic strategies for re-directing inflammatory autoimmune conditions.

Early postnatal life is characterized by a critical time period in which the developing neonatal immune system transitions from passive immunity, induced by protective maternal antibodies, to the competence of a fully functioning immune system. The inflammatory capability of both maternal and neonatal antibodies is governed by N-linked glycosylation of the Fc region, and though this has been examined extensively in adults, there is currently little information regarding antibody glycosylation patterns during early postnatal life. To characterize the murine IgG Fc glycosylation profile during early life, we used nano-LC-ESI-Qq-TOF mass spectrometry analysis to assess subclass specific Asn-297 glycosylation patterns in the serum of BALB/c mice from 5–60 days of age. From birth to adulthood, we observed a decline in proinflammatory Fc glycosylation in all IgG subclasses. This was shown by significantly reduced agalactosylated and monogalactosylated structures combined with increased sialylation after weaning at 45 and 60 days of age. This information indicates that the transition between neonatal life and adulthood in mice is accompanied by reduction of inflammatory IgG antibodies. Our study contributes to a growing body of literature indicating the importance of IgG Fc glycosylation and its association with inflammation during different life stages.