Expression of CD23 in the germinal center of thymus from myasthenia gravis patients

The Association Between Asthma and Risk of Myasthenia Gravis: A Systematic Review and Meta-analysis

PURPOSE

This study aimed to investigate the association between asthma and risk of myasthenia gravis (MG) using the method of systematic review and meta-analysis.

METHODS

Potentially eligible studies were identified from Medline and EMBASE databases from inception to July 2020 using search strategy that comprised terms for "Asthma" and "Myasthenia Gravis". Eligible cohort study must consist of one cohort of individuals with asthma and another cohort of individuals without asthma. Then, the study must report relative risk (RR) with 95% confidence intervals (95% CIs) of incident MG between the groups. Eligible case-control studies must include cases with MG and controls without MG. Then, the study must explore their history of asthma. Odds ratio (OR) with 95% CIs of the association between asthma status and MG must be reported. Point estimates with standard errors were retrieved from each study and were combined together using the generic inverse variance method.

RESULTS

A total of 6,835 articles were identified. After two rounds of independent review by five investigators, two cohort studies and three case-control studies met the eligibility criteria and were included into the meta-analysis. Pooled analysis showed that asthma was significantly associated with risk of MG with the pooled risk ratio of 1.38 (95% CI 1.02-1.86). Funnel plot was symmetric, which was not suggestive of publication bias.

CONCLUSION

The current study found a significant association between asthma and increased risk of MG.

Characterization of the thymus in Lrp4 myasthenia gravis: Four cases

Myasthenia gravis (MG) is an autoimmune disease of the neuromuscular junction. Most patients have pathogenic autoantibodies against the acetylcholine receptor (AChR). In the last years a novel subpopulation of MG patients has been described that harbors antibodies against low-density lipoprotein receptor-related protein 4 (Lrp4), another postsynaptic neuromuscular antigen. In early-onset AChR MG (EOMG), the thymus plays an important role in immunopathogenesis, and early thymectomy is beneficial. It is still unknown if the thymus plays any role in Lrp4-MG. In this pilot study, we compared thymus samples from four patients with Lrp4-MG (one pre-treated with immunosuppressive drugs), four non-MG controls and five EOMG patients (not pretreated with immunosuppressive drugs). Immunohistochemistry of the Lrp4-MG thymi revealed normal architecture, with normal numbers and distribution of B-cells, lymphoid follicles and Hassall's corpuscles. Primary CD23⁺ lymphoid follicles were similarly infrequent in Lrp4-MG and control thymic sections. In none of the control or Lrp4-MG thymi did we find secondary follicles with CD10⁺ germinal centers. These were evident in 2 of the 5 EOMG thymi, where primary lymphoid follicles were also more frequent on average, thus showing considerable heterogeneity between patients. Even if characteristic pathological thymic changes were not observed in the Lrp4 subgroup, we cannot exclude a role for the thymus in Lrp4-MG pathogenesis, since one Lrp4-MG patient went into clinical remission after thymectomy alone (at one year follow-up) and one more improved after thymectomy in combination with immunosuppressive therapy.

Higher risk of myasthenia gravis in patients with thyroid and allergic diseases: a national population-based study

The aim of this study was to determine the risk of myasthenia gravis (MG) in patients with allergic or autoimmune thyroid disease in a large cohort representing 99% of the population in Taiwan. Data from the Taiwan National Health Insurance Database were used to conduct retrospective analyses. The study comprised 1689 adult patients with MG who were 4-fold frequency matched to those without MG by sex, age, and assigned the same index year. Multivariate logistic regression models were used to calculate the odds ratios and 95% confidence intervals for the association between allergic or autoimmune thyroid disease and MG. An increased subsequent risk of MG was observed in the patients with allergic conjunctivitis (AC), allergic rhinitis, Hashimoto thyroiditis, and Graves disease. The adjusted odds ratios (aORs) were 1.93 (1.71-2.18), 1.26 (1.09-1.45), 2.87 (1.18-6.97), and 3.97 (2.71-5.83), respectively. The aORs increased from 1.63 (1.43-1.85) in a patient with only 1 allergic or autoimmune thyroid disease to 2.09 (1.75-2.49) in a patient with 2 thyroid or allergic diseases to 2.82 (2.19-3.64) in a patient with ≥3 thyroid or allergic diseases. MG was associated with the cumulative effect of concurrent allergic and autoimmune thyroid disease with combined AC and Hashimoto thyroiditis representing the highest risk (aOR = 15.62 [2.88-87.71]). This population-based case-control study demonstrates the association between allergic or autoimmune thyroid disease and the risk of MG. The highest risk of subsequent MG was associated with combined AC and Hashimoto thyroiditis.

Silencing miR-146a influences B cells and ameliorates experimental autoimmune myasthenia gravis

MicroRNAs have been shown to be important regulators of immune homeostasis as patients with aberrant microRNA expression appeared to be more susceptible to autoimmune diseases. We recently found that miR-146a was up-regulated in activated B cells in response to rat acetylcholine receptor (AChR) α-subunit 97-116 peptide, and this up-regulation was significantly attenuated by AntagomiR-146a. Our data also demonstrated that silencing miR-146a with its inhibitor AntagomiR-146a effectively ameliorated clinical myasthenic symptoms in mice with ongoing experimental autoimmune myasthenia gravis. Furthermore, multiple defects were observed after miR-146a was knocked down in B cells, including decreased anti-R97-116 antibody production and class switching, reduced numbers of plasma cells, memory B cells and B-1 cells, and weakened activation of B cells. Previously, miR-146a has been identified as a nuclear factor-κB-dependent gene and predicted to base pair with the tumour necrosis factor receptor-associated factor 6 (TRAF6) and interleukin-1 receptor-associated kinase 1 (IRAK1) genes to regulate the immune response. However, our study proved that miR-146a inhibition had no effect on the expression of TRAF6 and IRAK1 in B cells. This result suggests that the function of miR-146a in B cells does not involve these two target molecules. We conclude that silencing miR-146a exerts its therapeutic effects by influencing the B-cell functions that contribute to the autoimmune pathogenesis of myasthenia gravis.

Increased subsequent risk of myasthenia gravis in children with allergic diseases

Myasthenia gravis (MG) is an autoimmune disorder that affects the neuromuscular junction. The initiating factors of MG remain unclear. However, allergy has been regarded as a potential risk factor. We included 410 children with MG diagnosed between 2000 and 2008, as well as 1640 randomly selected controls. The odds ratios of MG were calculated to determine the association between MG and preexisting allergic diseases. The children with allergic diseases were at increased subsequent risk of MG, which was associated with the cumulative effect of the concurrent allergic diseases and the frequency of seeking medical care.

B-cell-activating factor and autoimmune myasthenia gravis

BAFF is a potent B-cell survival factor, and it plays an essential role in B-cell homeostasis and B-cell function in the periphery. Both normal and autoreactive B cells are BAFF dependent; however, excess BAFF promotes the survival, growth, and maturation of autoreactive B cells. When overexpressed, BAFF protects B cells from apoptosis, thereby contributing to autoimmunity. Three independent studies have shown higher BAFF levels in the circulation of MG patients. BAFF may play an important role in the pathogenesis of MG. BAFF antagonists may well provide new treatment options for MG patients, particularly those patients with thymic lymphoid follicular hyperplasia.

Comparison of the histological and immunohistochemical features of the thymus in young- and elderly-onset myasthenia gravis without thymoma

We performed histological and immunohistochemical analyses of the removed thymuses from 20 elderly (onset age > 60 years) and 23 young (onset age < 40 years) patients with myasthenia gravis (MG) who tested positive for serum anti-acetylcholine receptor (AChR) antibodies, but who did not have associated thymoma. In the elderly group, nine (45%) patients had accumulations of lymphocytes, indicating an atrophied thymus with loss of the basic structure. The elderly MG patients with atrophied thymic tissues had higher titres of anti-AChR antibody (59.6+/-81.0 nmol/L) than those with adipose infiltration of the thymus alone (20.1+/-20.9 nmol/L). In immunohistochemical studies using image analysis, both young patients and elderly patients with atrophied thymic tissues were found to have significantly higher levels of CD20 than age-matched controls (p < 0.005). Atrophied thymic tissues, often seen immunohistochemically in young MG patients, may also be found in elderly patients, particularly in those with high titres of the anti-AChR antibody, even though adipose infiltration is marked in these patients.

Lymphoid organ development: from ontogeny to neogenesis

The development of lymphoid organs can be viewed as a continuum. At one end are the 'canonical' secondary lymphoid organs, including lymph nodes and spleen; at the other end are 'ectopic' or tertiary lymphoid organs, which are cellular accumulations arising during chronic inflammation by the process of lymphoid neogenesis. Secondary lymphoid organs are genetically 'preprogrammed' and 'prepatterned' during ontogeny, whereas tertiary lymphoid organs arise under environmental influences and are not restricted to specific developmental 'windows' or anatomic locations. Between these two boundaries are other types of lymphoid tissues that are less developmentally but more environmentally regulated, such as Peyer's patches, nasal-associated lymphoid tissue, bronchial-associated lymphoid tissue and inducible bronchial-associated lymphoid tissue. Their regulation, functions and potential effects are discussed here.

Distinct profiles of Sjögren's syndrome patients with ectopic salivary gland germinal centers revealed by serum cytokines and BAFF

The formation of ectopic germinal centers (GC) has been described in Sjögren's syndrome (SS), although little is known about the molecular basis of this phenomenon. These structures are a focus of in situ autoantibody production and have been hypothesized to be involved in lymphomagenesis in SS patients. Serum cytokines also play an important role in SS pathogenesis in part via immune dysregulation and may therefore contribute to ectopic GC formation. Herein, highly multiplex cytokine screening of SS patients with (SSGC+) and without (SSGC-) GC formation was done to identify cytokine profiles that correlate with this phenomenon. Serum levels of B-cell activating factor (BAFF) were also screened as a potential biomarker of immune dysregulation in SS and SSGC formation. Univariate analysis demonstrated that serum levels of a broad spectrum of immune and inflammatory modulating cytokines are upregulated in SSGC+ and SSGC- patients relative to unaffected controls IL-1beta, IL-2, IL-6, IL-15, IFN-gamma and CCL4 (MIP-1beta). SSGC+ patients were distinguished from healthy individuals by higher levels of IL-4, IL-10, GM-CSF, IFN-alpha, CCL3 (MIP-1alpha), CCL11 (Eotaxin) and BAFF, while SSGC+ and SSGC- patients differed in CCL2 (MCP-1) expression. Discriminant function analysis (DFA), a multivariate discrimination method that uses observed differences to characterize groups when casual relationships are not well understood, was employed to identify a subset of these biomarkers that maximally discriminate among SSGC+, SSGC- and unaffected individuals. The biomarker having the strongest discriminatory power identified by DFA besides CCL11 (Eotaxin) and IFN-gamma was BAFF. The variables identified by DFA are interdependent and are often of mechanistic significance to the pathologic states they distinguish, suggesting that these factors modulate SS pathology and SSGC formation in a synergistic manner.

High frequency of allergic conjunctivitis in myasthenia gravis without thymoma

OBJECTIVES

To investigate the frequency of allergic disorders in myasthenia gravis (MG) patients and characterize the features of MG associated with allergic disorders.

METHODS

Frequencies of past and present common allergic disorders in 160 MG patients who visited the Department of Neurology, Kyushu University Hospital from April 2000 to July 2003 and in 81 neurological normal controls were studied.

RESULTS

Among various allergic disorders, the frequency of allergic conjunctivitis (AC) was significantly higher in MG patients (39/160, 24.4%, p(corr)=0.0112), especially with MG without thymoma (36/123, 29.3%, p(corr)=0.0016), in comparison to the controls (6/81, 7.4%). MG patients with AC showed a significantly higher rate of seronegative MG (43.6% vs. 17.4%, p=0.008) and a higher tendency of ocular MG (43.6% vs. 28.1%, p=0.071). Moreover, MG with AC had significantly lower anti-acetylcholine receptor antibody titers (median 6.8 nmol/l vs. median 23.6 nmol/l, p=0.0359) as well as a lower rate of coexisting thymoma (7.7% vs. 17.4%, p=0.016). The incidence of myasthenic crisis was also lower in MG with AC than without AC, yet the difference was not significant (7.7% vs. 15.7%).

CONCLUSION

There was a significant association of AC with MG especially for ocular or seronegative MG in cases without thymoma.

De novo lymph node formation in chronic inflammation of the human leg

Organized lymphoid tissue is the first line of antigenic defense. Recruited by antigen located in the non-lymphoid tissues, the infiltrating lymphocytes often organize themselves as follicle-like structures that contain germinal centers, similar to those in secondary lymphoid follicles of lymph nodes. These extranodal tertiary lymphoid follicles are found in various autoimmune diseases. We investigated 153 patients with protracted lymph stasis of the lower limb, caused by lymphatic damage incurred through soft tissue bacterial inflammation or mechanical trauma of soft tissues and bones. In 10% of patients with post-inflammatory, and in 25% with post-traumatic lymph stasis, "newly-formed" lymph nodes were detected by means of lymphoscintigraphy. They were located along the large calf and thigh veins. Although scattered nodes are normally detected in these areas, the number and total mass of visualized nodes substantially exceeded those seen in healthy subjects. The calculated surface area of "newly formed" nodes attained 50-70% of the area of ipsilateral inguinal nodes. Histological evaluation of nodal biopsy specimens in three such patients revealed, in one, a lymph node structure without differentiation into cortical and medullary areas, and in a second, a follicle-like structure within a dilated lymph vessel. Lymph clot removed from another dilated vessel contained a lymphocyte/dendritic cell aggregate. The "newly formed" nodes likely originate from primordial lymphoid follicles and/or lymphoid cell aggregates formed in response to chronic stimulation by microbial products and self-antigens from the damaged tissues. Detection of "newly-formed" lymph nodes in the limb is evidence of an ongoing inflammatory process and requires appropriate therapy.

Diminished peripheral blood memory B cells and accumulation of memory B cells in the salivary glands of patients with Sjögren's syndrome

OBJECTIVE

To delineate the mechanism of the abnormalities in B cell biology found in patients with primary Sjögren's syndrome (SS).

METHODS

The distribution of peripheral B cell subpopulations in 21 patients with primary SS was analyzed by immunofluorescence labeling and flow cytometry. Immunoglobulin rearrangements were analyzed in single B cells isolated from the peripheral blood and parotid glands by fluorescence-activated cell sorting.

RESULTS

A significant reduction in the number of peripheral CD27+ memory B cells was found in SS patients, including a significantly reduced number of CD27+/IgD+/IgM+/CD5+ memory B cells. Remarkably, SS patients with secondary lymphoma uniquely exhibited an increase in CD27-expressing peripheral B cells, including CD27(high) plasmablasts. Molecular analysis for mutated Ig gene rearrangements confirmed that CD27 expression distinguished naive and memory cells in SS. In contrast to the peripheral blood, the majority of parotid B cells from 1 patient examined exhibited both the mutational status and phenotype of memory B cells. Accordingly, the mutational frequencies of V(H) rearrangements were significantly greater in parotid B cells than in peripheral blood B cells, whereas the V(H) gene repertoire appeared to be very similar between the compartments.

CONCLUSION

These data indicate that there is an accumulation/retention of memory B cells in the inflamed salivary glands of SS patients. It is possible that preferential accumulation of CD27+ memory B cells in the inflamed parotid gland explains their reduction in the peripheral blood.

Chemokines and cell trafficking in Sjögren's syndrome

Sjögren's syndrome is a chronic inflammatory condition affecting exocrine glands, manifested clinically as dry eyes and dry mouth. It arises secondary to systemic immune-mediated diseases such as rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), scleroderma or 'primary' Sjögren's syndrome. Histologically it is characterized by peri-ductal aggregates of CD4 T lymphocytes, the frequent occurrence of ectopic germinal centres and, in some patients, B-cell infiltration of ductal epithelium (myoepithelial sialadenitis). This latter lesion is the precursor for the development of low grade (MALT) B-cell lymphoma. The identification over recent years of chemokines and their receptors enables us to address the specific processes involved in the migration of inflammatory cells into exocrine glands, the development of their secondary structures and patterns of retention within the glands and potentially the subsequent transformation of B cells into mucosa associated lymphoid tissue (MALT) lymphoma.

Tissue Inhibitor of Metalloproteinase (TIMP)-1 Induces Differentiation and an Antiapoptotic Phenotype in Germinal Center B Cells

Tissue inhibitors of metalloproteinases (TIMPs) have been shown to be multifunctional factors. Contrasting with their enzyme-inhibitory activity, TIMPs also promote cell growth. Previously, we have reported an enhanced expression of TIMP-1 by normal reactive B cells and high-grade lymphomas. In the present study, a series of Burkitt’s lymphoma (BL) cell lines were analyzed for their expression of TIMP-1. TIMP-1 expression correlates with upregulation of activation and survival markers. TIMP-1–negative cells express the phenotype associated with group I BL lines and Epstein-Barr virus (EBV)-negative, nonendemic BLs (CD10+, CD38+, sIg+, and CD77+). However, TIMP-1+ BL lines showed group II/III BL phenotype, downregulation of the above markers, and upregulation and secretion of the activation marker CD23. Also, TIMP-1+ cells have high levels of CD40 expression. To determine whether TIMP-1 is directly involved in the BL phenotype, an EBV-negative BL line JD38 was infected with timp-1–expressing retrovirus and analyzed. In the absence of EBV, upregulation of TIMP-1 is sufficient to induce the same phenotype seen in TIMP-1+, EBV+ BL lines (CD10−, CD38−, sIg−, CD77−, CD23+, CD40 bright). This study not only suggests a role for TIMP-1 in BLs, but also supports its value as a prognostic factor.

This is a US government work. There are no restrictions on its use.

Tissue Inhibitor of Metalloproteinase (TIMP)-1 Induces Differentiation and an Antiapoptotic Phenotype in Germinal Center B Cells

Tissue inhibitors of metalloproteinases (TIMPs) have been shown to be multifunctional factors. Contrasting with their enzyme-inhibitory activity, TIMPs also promote cell growth. Previously, we have reported an enhanced expression of TIMP-1 by normal reactive B cells and high-grade lymphomas. In the present study, a series of Burkitt’s lymphoma (BL) cell lines were analyzed for their expression of TIMP-1. TIMP-1 expression correlates with upregulation of activation and survival markers. TIMP-1–negative cells express the phenotype associated with group I BL lines and Epstein-Barr virus (EBV)-negative, nonendemic BLs (CD10+, CD38+, sIg+, and CD77+). However, TIMP-1+ BL lines showed group II/III BL phenotype, downregulation of the above markers, and upregulation and secretion of the activation marker CD23. Also, TIMP-1+ cells have high levels of CD40 expression. To determine whether TIMP-1 is directly involved in the BL phenotype, an EBV-negative BL line JD38 was infected with timp-1–expressing retrovirus and analyzed. In the absence of EBV, upregulation of TIMP-1 is sufficient to induce the same phenotype seen in TIMP-1+, EBV+ BL lines (CD10−, CD38−, sIg−, CD77−, CD23+, CD40 bright). This study not only suggests a role for TIMP-1 in BLs, but also supports its value as a prognostic factor.

This is a US government work. There are no restrictions on its use.

Germinal centre cell kinetics

The germinal centre is a fundamental component of the humoral immune response, representing a unique microenvironment where antigen-activated B lymphocytes undergo clonal expansion, mutate their immunoglobulin, and are subject to a stringent selection process based on their antigen affinity. This review highlights recent advances in the understanding of the cell kinetic process of activation, proliferation, differentiation, and death of germinal centre cells, which are beginning to provide important insights into the regulation of this highly complex reaction. Their definition may have considerable pathological import given the involvement of the germinal centre in non-Hodgkin's lymphomas and recent evidence suggesting that abnormal germinal centre reactions may be involved in the pathogenesis of Hodgkin's disease and some autoimmune diseases.