The Neuroimmunology of Guillain-Barré Syndrome and the Potential Role of an Aging Immune System

The characteristics of Guillain-Barre syndrome in children in pre-COVID-19 and during the COVID-19 pandemic: A cross-sectional study

Background and Aims

In the pathophysiology of Guillain-Barre syndrome (GBS), inflammation and immunity are believed to play a key role. The neutrophil-lymphocyte ratio (NLR), monocyte-lymphocyte ratio (MLR), and platelet-lymphocyte ratio (PLR) have been recently identified as potential markers of inflammation or immunity. This study aimed to investigate whether NLR, MLR, and PLR are associated with GBS characteristics in children. We also assessed the impact of the COVID-19 pandemic on the characteristics of GBS in Iran.

Methods

In this retrospective cross-sectional study, we reviewed the records of all 150 children diagnosed with GBS in the Children's Medical Center hospital affiliated with Tehran University of Medical Sciences (TUMS) from March 2017 until March 2022. The TUMS research ethics committee approved the study (Ethics code: IR.TUMS.CHMC.REC.1399.125). Patients' data including gender, age, clinical symptoms, laboratory findings, and electrodiagnostic study results were collected and analyzed.

Results

This study involved 150 children, comprising 93 boys and 57 girls, with an average age of 7.53 ± 3.75 years. The analysis demonstrated that the number of hospitalization days increased with an increase in NLR (p = 0.025). Moreover, patients with abnormal electrodiagnostic study patterns had a higher risk of intensive care unit (ICU) admission (p: 0.027), although according to binary logistic regression, respiratory failure at admission time was the only significant factor increasing the risk of ICU admission (p = 0.035). The study also found that the pandemic has resulted in a shift from acute inflammatory demyelinating polyneuropathy to acute motor axonal neuropathy as the most common EMG-NCV pattern in our patients (p < 0.001).

Conclusion

We found that higher NLR was associated with a longer hospitalization duration and could potentially distinguish between severe and mild cases of GBS. We have also shown that the COVID-19 pandemic has changed our patients' most frequent electromyography and nerve conduction velocity (EMG-NCV) patterns.

Neurological risks of COVID-19 in women: the complex immunology underpinning sex differences

The COVID-19 pandemic has uncovered many mysteries about SARS-CoV-2, including its potential to trigger abnormal autoimmune responses. Emerging evidence suggests women may face higher risks from COVID-induced autoimmunity manifesting as persistent neurological symptoms. Elucidating the mechanisms underlying this female susceptibility is now imperative. We synthesize key insights from existing studies on how COVID-19 infection can lead to immune tolerance loss, enabling autoreactive antibodies and lymphocyte production. These antibodies and lymphocytes infiltrate the central nervous system. Female sex hormones like estrogen and X-chromosome mediated effects likely contribute to dysregulated humoral immunity and cytokine profiles among women, increasing their predisposition. COVID-19 may also disrupt the delicate immunological balance of the female microbiome. These perturbations precipitate damage to neural damage through mechanisms like demyelination, neuroinflammation, and neurodegeneration - consistent with the observed neurological sequelae in women. An intentional focus on elucidating sex differences in COVID-19 pathogenesis is now needed to inform prognosis assessments and tailored interventions for female patients. From clinical monitoring to evaluating emerging immunomodulatory therapies, a nuanced women-centered approach considering the hormonal status and immunobiology will be vital to ensure equitable outcomes. Overall, deeper insights into the apparent female specificity of COVID-induced autoimmunity will accelerate the development of solutions mitigating associated neurological harm.

The neutrophil-to-lymphocyte ratio as a prognostic biomarker in Guillain-Barre syndrome: a systematic review with meta-analysis

Background and objectives

Guillain-Barre syndrome (GBS) is an immune-mediated neuropathy. This has raised the possibility that the neutrophil-lymphocyte ratio (NLR) may be a biomarker of its activity. We conducted a systematic review and meta-analysis to summarize the evidence of NLR as a potential biomarker for GBS.

Methods

We systematically searched databases (PubMed, Ovid-Medline, Embase, Scopus, Web of Science, SciELO Citation Index, LILACS, and Google Scholar) until October 2021 for studies evaluating pre-treatment NLR values in GBS patients. A meta-analysis using a random-effects model to estimate pooled effects was realized for each outcome and a narrative synthesis when this was not possible. Subgroup and sensitivity analysis were realized. GRADE criteria were used to identify the certainty of evidence for each result.

Results

Ten studies from 745 originally included were selected. Regarding GBS patients versus healthy controls, a meta-analysis of six studies (968 patients) demonstrated a significant increase in NLR values in GBS patients (MD: 1.76; 95% CI: 1.29, 2.24; I2 = 86%) with moderate certainty due to heterogeneity of GBS diagnosis criteria used. Regarding GBS prognosis, assessed by Hughes Score ≥ 3, NLR had a sensitivity between 67.3 and 81.5 and a specificity between 67.3 and 87.5 with low certainty due to imprecision, and heterogeneity. In relation to respiratory failure, NLR had a sensitivity of 86.5 and specificity of 68.2 with high and moderate certainty, respectively.

Discussion

With moderate certainty, mean NLR is higher in GBS patients compared to healthy controls. Furthermore, we found that NLR could be a prognostic factor for disability and respiratory failure with low and moderate certainty, respectively. These results may prove useful for NLR in GBS patients; however, further research is needed.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/, identifier: CRD42021285212.

Molecular, Electrophysiological, and Ultrasonographic Differences in Selected Immune-Mediated Neuropathies with Therapeutic Implications

The spectrum of immune-mediated neuropathies is broad and the different subtypes are still being researched. With the numerous subtypes of immune-mediated neuropathies, establishing the appropriate diagnosis in normal clinical practice is challenging. The treatment of these disorders is also troublesome. The authors have undertaken a literature review of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), Guillain-Barre syndrome (GBS) and multifocal motor neuropathy (MMN). The molecular, electrophysiological and ultrasound features of these autoimmune polyneuropathies are analyzed, highlighting the differences in diagnosis and ultimately treatment. The immune dysfunction can lead to damage to the peripheral nervous system. In practice, it is suspected that these disorders are caused by autoimmunity to proteins located in the node of Ranvier or myelin components of peripheral nerves, although disease-associated autoantibodies have not been identified for all disorders. The electrophysiological presence of conduction blocks is another important factor characterizing separate subgroups of treatment-naive motor neuropathies, including multifocal CIDP (synonyms: multifocal demyelinating neuropathy with persistent conduction block), which differs from multifocal motor neuropathy with conduction block (MMN) in both responses to treatment modalities and electrophysiological features. Ultrasound is a reliable method for diagnosing immune-mediated neuropathies, particularly when alternative diagnostic examinations yield inconclusive results. In overall terms, the management of these disorders includes immunotherapy such as corticosteroids, intravenous immunoglobulin or plasma exchange. Improvements in clinical criteria and the development of more disease-specific immunotherapies should expand the therapeutic possibilities for these debilitating diseases.

COVID-19 as a trigger of Guillain-Barré syndrome: A review of the molecular mechanism

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused a pandemic with serious complications. After coronavirus disease 2019 (COVID-19), several post-acute COVID-19 syndromes (PACSs) and long-COVID sequels were reported. PACSs involve many organs, including the nervous, gustatory, and immune systems. One of the PACSs after SARS-CoV-2 infection and vaccination is Guillain-Barré syndrome (GBS). The incidence rate of GBS after SARS-CoV-2 infection or vaccination is low. However, the high prevalence of COVID-19 and severe complications of GBS, for example, autonomic dysfunction and respiratory failure, highlight the importance of post-COVID-19 GBS. It is while patients with simultaneous COVID-19 and GBS seem to have higher admission rates to the intensive care unit, and demyelination is more aggressive in post-COVID-19 GBS patients. SARS-CoV-2 can trigger GBS via several pathways like direct neurotropism and neurovirulence, microvascular dysfunction and oxidative stress, immune system disruption, molecular mimicry, and autoantibody production. Although there are few molecular studies on the molecular and cellular mechanisms of GBS occurrence after SARS-CoV-2 infection and vaccination, we aimed to discuss the possible pathomechanism of post-COVID-19 GBS by gathering the most recent molecular evidence.

Characteristics of Guillain-Barré syndrome in super-elderly individuals

BACKGROUND

Japan has the world's largest super-aging population, and the number of elderly patients with various diseases is increasing. Herein, we reported the characteristics of super-elderly patients, aged over 80 years, with Guillain-Barré syndrome (GBS), a typical neuroimmune disease.

METHODS

During the period 2019-2021, 74 patients over the age of 80 years diagnosed with GBS at Kindai university were analyzed as the super-elderly group patients. The control group comprised 74 consecutive patients aged < 79 years, under the same conditions. GBS was diagnosed using Brighton diagnostic criteria. Electrophysiology was assessed using the Ho criteria.

RESULTS

The mean age was 83.5 years in the super-elderly group and 51.7 years in the control group. Prior infection was recognized in 50% of cases in the super-elderly group and 77% of cases in the control group with fewer cases in the super-elderly group. The mean number of days until peak symptom presentation was longer in the super-elderly group. The percentage who required a ventilator was significantly higher among the super-elderly group than among the control group. Hughes functional grading scale was more severe in the super-elderly group. Electrophysiological examination revealed the demyelinating form was particularly common in the super-elderly group. Intravenous immunoglobulin was the most common treatment in both the groups, with no difference in efficacy.

CONCLUSIONS

Super-elderly onset GBS tends to be severe, therefore it is important to diagnose and treat appropriately, even in the absence of prior episodes of infection.

Real-world data on the incidence and risk of Guillain-Barré syndrome following SARS-CoV-2 vaccination: a prospective surveillance study

Increasing evidence suggests an association between SARS-CoV-2 vaccines and Guillain-Barré syndrome (GBS). Nevertheless, little is understood about the contributing risk factors and clinical characteristics of GBS post SARS-CoV-2 vaccination. In this prospective surveillance study of 38,828,691 SARS-CoV-2 vaccine doses administered from February 2021 to March 2022 in the Gyeonggi Province, South Korea, 55 cases of GBS were reported post vaccination. We estimated the incidence rate of GBS per million doses and the incidence rate ratio for the vaccine dose, mechanism, age, and sex. Additionally, we compared the clinical characteristics of GBS following mRNA-based and viral vector-based vaccinations. The overall incidence of GBS following SARS-CoV-2 vaccination was 1.42 per million doses. Viral vector-based vaccines were associated with a higher risk of GBS. Men were more likely to develop GBS than women. The third dose of vaccine was associated with a lower risk of developing GBS. Classic sensorimotor and pure motor subtypes were the predominant clinical subtypes, and demyelinating type was the predominant electrodiagnostic subtype. The initial dose of viral-vector based vaccine and later doses of mRNA-based vaccine were associated with GBS, respectively. GBS following SARS-CoV-2 vaccination may not be clinically distinct. However, physicians should pay close attention to the classic presentation of GBS in men receiving an initial dose of viral vector-based SARS-CoV-2 vaccines.

Deciphering the Role of Schwann Cells in Inflammatory Peripheral Neuropathies Post Alphavirus Infection

Old world alphaviruses (e.g., chikungunya) are known to cause severe acute and chronic debilitating arthralgia/arthritis. However, atypical neurological manifestations and, in particular, unexpected cases of acute inflammatory Guillain-Barre syndrome (GBS) have been associated with the arthritogenic alphaviruses. The pathogenesis of alphavirus-associated GBS remains unclear. We herein addressed for the first time the role of Schwann cells (SC) in peripheral neuropathy post-alphaviral infection using the prototypical ONNV alphavirus model. We demonstrated that human SC expressed the recently identified alphavirus receptor MxRA8 and granting viral entry and robust replication. A canonical innate immune response was engaged by ONNV-infected SC with elevated gene expression for RIG-I, MDA5, IFN-β, and ISG15 and inflammatory chemokine CCL5. Transcription levels of prostaglandin E2-metabolizing enzymes including cPLA2α, COX-2, and mPGES-1 were also upregulated in ONNV-infected SC. Counterintuitively, we found that ONNV failed to affect SC regenerative properties as indicated by elevated expression of the pro-myelinating genes MPZ and MBP1 as well as the major pro-myelin transcription factor Egr2. While ONNV infection led to decreased expression of CD55 and CD59, essential to control complement bystander cytotoxicity, it increased TRAIL expression, a major pro-apoptotic T cell signal. Anti-apoptotic Bcl2 transcription levels were also increased in infected SC. Hence, our study provides new insights regarding the remarkable immunomodulatory role of SC of potential importance in the pathogenesis of GBS following alphavirus infection.

Campylobacter jejuni and Postinfectious Autoimmune Diseases: A Proof of Concept in Glycobiology

Glycans, one of the most diverse groups of macromolecules, are ubiquitous constituents of all cells and have many critical functions, including the interaction between microbes and their hosts. One of the best model organisms to study the host-pathogen interaction, the gastrointestinal pathogen Campylobacter jejuni dedicates extensive resources to glycosylation and exhibits a diverse array of surface sugar-coated displays. The first bacterium where N-linked glycosylation was described, C. jejuni can additionally modify proteins by O-linked glycosylation, has extracellular capsular polysaccharides that are important for virulence and represent the major determinant of the Penner serotyping scheme, and has outer membrane lipooligosaccharides that participate in processes such as colonization, survival, inflammation, and immune evasion. In addition to causing gastrointestinal disease and extraintestinal infections, C. jejuni was also linked to postinfectious autoimmune neuropathies, of which Guillain-Barré syndrome (GBS) and Miller Fisher syndrome (MFS) are the most extensively characterized ones. These postinfectious autoimmune neuropathies occur when specific bacterial surface lipooligosaccharides mimic gangliosides in the host nervous system. C. jejuni provided the first proof of concept for the involvement of molecular mimicry in the pathogenesis of an autoimmune disease and, also, for the ability of a bacterial polymorphism to shape the clinical presentation of the postinfectious autoimmune neuropathy. The scientific journey that culminated with elucidating the mechanistic details of the C. jejuni-GBS link was the result of contributions from several fields, including microbiology, structural biology, glycobiology, genetics, and immunology and provides an inspiring and important example to interrogate other instances of molecular mimicry and their involvement in autoimmune disease.

Role of the Neutrophil to Lymphocyte Ratio in Guillain Barré Syndrome: A Systematic Review and Meta-Analysis

In this study, we conducted a systematic review and meta-analysis regarding the role of the neutrophil to lymphocyte ratio (NLR) in Guillain Barré syndrome (GBS). The most recent update to the search was on July 18, 2022, through the databases of Web of Science, PubMed, Embase, and Scopus. The Newcastle-Ottawa scale was used for quality assessment of included studies. Finally, 14 studies were included in the review, and among them, ten studies were included in the meta-analysis. Our results showed that NLR levels were significantly increased in the patients with GBS compared with healthy controls (SMD = 1.05; 95%CI = 0.59 to 1.50, P < 0.001). After treatment, NLR levels were decreased to the extent that they became similar to healthy controls (SMD = −0.03, 95%CI = −0.29 to 0.22, P = 0.204). Moreover, NLR was a stable predictor of outcome or response to treatment in such patients (SMD = 1.01, 95%CI = 0.65 to 1.37, P < 0.001); the higher the NLR, the worse the outcome. In addition, patients who underwent mechanical ventilation had higher levels of NLR compared to those who did not (SMD = 0.93, 95%CI = 0.05 to 1.82, P = 0.03). However, NLR levels were not different among distinct GBS subtypes, so it could not distinguish among them. In conclusion, our analysis indicates that the NLR levels are highly elevated in patients with GBS. Therefore, the NLR has the potential to be used as a biomarker to inform diagnosis, prognosis, or treatment responses in GBS, and future studies are warranted.

Aging and the immune response in diabetic peripheral neuropathy

A large proportion of older individuals with diabetes go on to develop diabetic peripheral neuropathy (DPN). DPN is associated with an increase in inflammatory cells within the peripheral nerve, activation of nuclear factor kappa-light-chain-enhancer of activated B cells and receptors for advanced glycation end products/advanced glycation end products pathways, aberrant cytokine expression, oxidative stress, ischemia, as well as pro-inflammatory changes in the bone marrow; all processes that may be exacerbated with age. We review the immunological features of DPN and discuss whether age-related changes in relevant immunological areas may contribute to age being a risk factor for DPN.