Thymoma-associated myasthenia gravis: Clinical features and predictive value of antiacetylcholine receptor antibodies in the risk of recurrence of thymoma

Somatic mutations of thymic epithelial tumors with myasthenia gravis

Background

Thymic epithelial tumors are rare malignant neoplasms that are frequently associated with paraneoplastic syndromes, especially myasthenia gravis. GTF2I is an oncogene mutated in a subgroup of thymomas that is reputed to drive their growth. However, for GTF2I wild-type tumors, the relevant mutations remain to be identified.

Methods

We performed a meta-analysis and identified 4,208 mutations in 339 patients. We defined a panel of 63 genes frequently mutated in thymic epithelial tumors, which we used to design a custom assay for next-generation sequencing. We sequenced tumor DNA from 67 thymomas of patients with myasthenia gravis who underwent resection in our institution.

Results

Among the 67 thymomas, there were 238 mutations, 83 of which were in coding sequences. There were 14 GTF2I mutations in 6 A, 5 AB, 2 B2 thymomas, and one in a thymoma with unspecified histology. No other oncogenes showed recurrent mutations, while sixteen tumor suppressor genes were predicted to be inactivated. Even with a dedicated assay for the identification of specific somatic mutations in thymic epithelial tumors, only GTF2I mutations were found to be significantly recurrent.

Conclusion

Our evaluation provides insights into the mutational landscape of thymic epithelial tumors, identifies recurrent mutations in different histotypes, and describes the design and implementation of a custom panel for targeted resequencing. These findings contribute to a better understanding of the genetic basis of thymic epithelial tumors and may have implications for future research and treatment strategies.

Expression of Programmed Cell Death 1 Ligand 2 in Patients With Thymoma and Thymomatous Myasthenia Gravis

OBJECTIVES

This study aimed to examine the expression of programmed cell death 1 ligand 2 (PD-L2) in thymoma and thymomatous myasthenia gravis (MG).

METHODS

The records of 70 patients with thymoma receiving surgical resection between January 2017 and December 2018 were retrospectively reviewed. Thymoma PD-L2 expression was evaluated by immunohistochemistry staining. Associations between PD-L2 expression and clinicopathologic features were examined.

RESULTS

PD-L2 expression was positive in 41 patients (58.6%) and negative in 29 patients (41.4%). Of them, 33 had thymomatous MG. Patients with MG were more likely to be 50 years of age or younger (69.70% vs 35.14%); have more World Health Organization (WHO) type B thymomas (84.85% vs 64.86%); have tumors of smaller size (4.09 ± 2.33 cm vs 6.47 ± 2.42 cm); have positive PD-L2 expression (78.79% vs 40.54%); and have a higher percentage of PD-L2-positive cells, higher PD-L2 expression intensity, and score (all P < .05). Positive PD-L2 expression was associated with more type B thymomas, higher Masaoka-Koga stage, smaller tumor size, ectopic thymus, and MG (all P < .05). Factors significantly associated with MG were age under 50 years, tumor size less than 5 cm, and positive PD-L2 expression (all P < .05).

CONCLUSIONS

Thymoma PD-L2 expression is significantly associated with thymomatous MG and WHO histologic types B2 and B3.

Poor responses and adverse outcomes of myasthenia gravis after thymectomy: Predicting factors and immunological implications

Myasthenia gravis (MG) has been recognized as a series of heterogeneous but treatable autoimmune conditions. As one of the indispensable therapies, thymectomy can achieve favorable prognosis especially in early-onset generalized MG patients with seropositive acetylcholine receptor antibody. However, poor outcomes, including worsening or relapse of MG, postoperative myasthenic crisis and even post-thymectomy MG, are also observed in certain scenarios. The responses to thymectomy may be associated with the general characteristics of patients, disease conditions of MG, autoantibody profiles, native or ectopic thymic pathologies, surgical-related factors, pharmacotherapy and other adjuvant modalities, and the presence of comorbidities and complications. However, in addition to these variations among individuals, pathological remnants and the abnormal immunological milieu and responses potentially represent major mechanisms that underlie the detrimental neurological outcomes after thymectomy. We underscore these plausible risk factors and discuss the immunological implications therein, which may be conducive to better managing the indications for thymectomy, to avoiding modifiable risk factors of poor responses and adverse outcomes, and to developing post-thymectomy preventive and therapeutic strategies for MG.

An unusual presentation of thymoma: dysgeusia, ulcerative colitis, keratoconjunctivitis sicca, autoimmune retinopathy and myasthenia gravis

A 41-year-old female presented with dysgeusia, dry eyes, nyctalopia with progressive visual field constriction (due to autoimmune retinopathy) and gastrointestinal symptoms (due to ulcerative colitis). She was subsequently admitted to intensive care with a myasthenic crisis, and CT of the thorax demonstrated a thymoma.Following thymectomy and adjuvant radiotherapy, she has remained in complete remission from her ulcerative colitis and myasthenia gravis, her retinopathy has stabilised and there has been no thymoma recurrence over a 10-year postoperative period. There was a brief relapse of her dysgeusia (causing weight loss) and dry eye symptoms 3 years after her surgery, which resolved 8 months later. While the association of thymomas with paraneoplastic syndromes (PNS) is well established, it is unusual to present with multiple PNS, and some of these have only been documented in sparse case reports to date. Thymectomy played a crucial role in improvement and stabilisation of her PNS.

Comparing the safety and efficacy of thoracoscopic surgery and thoracotomy for thymoma: a systematic review and meta-analysis

BACKGROUND

To systematically evaluate the efficacy of thoracoscopic surgery compared to traditional thoracotomy for thymic tumors.

METHODS

We performed a literature search on computer of the PubMed, Embase, Cochrane Library, Web of Science, China Biology Medicine (CBM), WanFang, and China national knowledge infrastructure (CNKI) databases from the date of establishment of the database to April 2021, and retrieved randomized controlled trials (RCTs) and cohort studies on thoracoscopic surgery and thoracotomy with conventional open thoracic surgery. After independent screening of the literature by two assessors, the relevant data was extracted and the risk of bias in the included studies was evaluated. RevMan 5.3 software was used to perform the analysis.

RESULTS

Five RCTs and eight cohort studies were ultimately included, with a total of 1,093 patients. The results of meta-analysis showed that compared with traditional thoracoscopic surgery, thoracoscopy had shorter surgery duration (OR =22.2, 95% CI: -31.92, -12.52, P<0.00001), ICU stay (OR =0.29, 95% CI: 0.20, 0.42, P<0.00001), and hospitalization time (OR =0.531, 95% CI: 0.41, 0.69, P<0.00001) times, as well as reduced chest tube drainage time (OR =0.49, 95% CI: 0.33, 0.73, P=0.0004), less intraoperative bleeding (OR =43.27, 95% CI: -50.94, -35.60, P<0.00001), and a lower incidence of postoperative complications (OR =0.19, 95% CI: 0.11, 0.34, P<0.00001). However, the tumor recurrence rate was not significantly different between the two procedures (OR =0.69, 95% CI: 0.32, 1.48, P=0.34).

DISCUSSION

The existing evidence suggests that thoracoscopic surgery has shorter surgery duration, ICU stay time, hospitalization time, reduced thoracic tube drainage, less intraoperative bleeding, and a lower incidence of postoperative complications compared with traditional thoracotomy surgery. However, due to the poor quality of the included research, more high-quality studies need to be conducted to verify the above conclusions.

Factors affecting improvement of neurologic status evaluated by Quantitative Myasthenia Gravis Score for patients with thymomatous myasthenia gravis after extended thymectomy

Background

The length of time for clinical improvement of patients with thymomatous myasthenia gravis (MG) after extended thymectomy is not clear. The purpose of this study was to determine the length of time after thymectomy in patients with thymomatous MG to achieve a 3-point reduction of Quantitative Myasthenia Gravis Score (QMGS), and identify variables associated with a failure to achieve the reduction.

Methods

The records of patients with thymomatous MG who underwent extended thymectomy from January 2005 to December 2018 were retrospectively reviewed. The primary end point was a reduction of 3 points of QMGs and the secondary end point was another reduction of 3 points of QMGs.

Results

A total of 481 patients were included in the analysis, the mean age of the patients was 41.63 ± 8.55 years, and approximately 60% were male. The median time to achieve a 3 point decrease in QMGS was 6 months, and the median time to achieve another 3 point decrease was 30 months. Multivariable analysis indicated that age ≥ 42 years and Masaoka-Koga stage > I were associated with a lower probability of achieving a 3 point decrease in QMGS (HR = 0.55 and 0.65, respectively). Likewise, multivariable analysis indicated that age ≥ 42 years and Masaoka-Koga stage > I were associated with a lower probability of achieving a second 3 point decrease in QMGS (HR = 0.53 and 0.53, respectively).

Conclusions

In patients with thymomatous MG who receive thymectomy, age ≥ 42 years and Masaoka-Koga stage > I are associated with a worse prognosis and failure to achieve a 3 point decrease in QMGS.

Improving laboratory diagnostics in myasthenia gravis

Introduction: Myasthenia gravis (MG) is a prototypical autoimmune disease, characterized by pathogenic autoantibodies targeting structures of the neuromuscular junction. Radioimmunoprecipitation assays (RIPAs) represent the gold standard for their detection. However, new methods are emerging to complement, or overcome RIPAs, also with the perspective of eliminating the use of radioactive reagents.Areas covered: We discuss advances in laboratory methods, prompted especially by cell-based assays (CBAs), for the detection of the autoantibodies of MG diagnostics, above all those to the nicotinic acetylcholine receptor (AChR), muscle-specific kinase (MuSK), and low molecular-weight receptor-related low-density lipoprotein-4 (LRP4).Expert opinion: CBA technology makes AChRs aggregate on cell membranes, thus allowing to detect autoantibodies to clustered AChRs, with reduction of seronegative MG cases. The diagnostic relevance of RIPA/CBA-measurable LRP4 antibodies is still unclear, in Caucasian patients at least. Live CBAs for the detection of AChR, MuSK, and LRP4 antibodies might represent an alternative to RIPAs, but first require full validation. CBAs could be used as screening tests, limiting RIPAs for antibody quantification. To this end, ELISAs might be an alternative.Fixation procedures preserving enough degree of antigen conformationality could yield AChR and MuSK CBAs suitable for a wide use in clinical-chemistry laboratories.

MiR-522-3p inhibits proliferation and activation by regulating the expression of SLC31A1 in T cells

We investigated the role of miR-522-3p in thymoma-associated myasthenia gravis (TAMG), and the mechanism of action in T cells. The miR-522-3p expression in normal serum, non-thymoma MG patient serum and TAMG patient serum and tissues was detected by quantitative real-time PCR (qRT-PCR), respectively. We assessed miR-522-3p expression in Jurkat cells and human CD4⁺ T cells after activation by anti-CD3 and anti-CD28 using qRT-PCR. The viability, proliferation, cycle distribution and the levels of CD25, CD69, interleukin-2 (IL-2) and IL-10 in transfected Jurkat cells were detected by Cell counting kit-8, 5-ethynyl-2'-deoxyuridine (EdU), flow cytometry, qRT-PCR, respectively. Targeting relationships of miR-522-3p and SLC31A1 were predicted and validated by bioinformatics analysis and dual-luciferase reporter. The viability, proliferation, cycle distribution and the levels of SLC31A1, CD25, CD69, IL-2 and IL-10 in transfected Jurkat cells were detected by above methods and western blot. The miR-522-3p expression was declined in TAMG and activated T cells. MiR-522-3p inhibitor promoted cell viability, EdU positive cells, cycle progression, and the level of CD25, CD69, IL-2 and IL-10 in Jurkat cells, while the effect of miR-522-3p mimic was the opposite. SLC31A1 was targeted by miR-522-3p, and miR-522-3p inhibited SLC31A1 expression. Overexpressed SLC31A1 reversed the inhibitory effects of miR-522-3p mimic on cell viability, EdU positive cell, cycle progression, and the levels of IL-2 and IL-10 in transfected Jurkat cells. MiR-522-3p expression was down-regulated in TAMG, and miR-522-3p inhibited proliferation and activation by regulating SLC31A1 expression in T cells.

Neobavaisoflavone protects osteoblasts from dexamethasone-induced oxidative stress by upregulating the CRNDE-mediated Nrf2/HO-1 signaling pathway

Neobavaisoflavone (NBIF) is a flavonoid, which has a variety of pharmacological activities. However, the mechanism of NBIF in the treatment of osteoporosis still needs further exploration. The differentiation of osteoblast MC-3T3-E1 cells after treatment was observed by Alizarin red staining. Cell counting kit-8 and flow cytometry were used to detect viability, apoptosis, and reactive oxygen species (ROS) levels of treated MC-3T3-E1 cells, respectively. Malondialdehyde (MDA), lactate dehydrogenase (LDH), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) were tested by ELISA kits. The expressions of lncRNA MALAT1, MEG3, CRNDE, Runx2, osteocalcin (OCN), osteopontin (OPN), collagen I (col-I), nuclear Nrf2, cytoplasm Nrf2, heme oxygenase-1 (HO-1) and quinone oxidoreductase 1 (NQO1) in treated MC-3T3-E1 cells were examined by Quantitative real-time PCR or Western blot. Dexamethasone (Dex) inhibited the viability of MC-3T3-E1 cells, while the appropriate amount of NBIF had no significantly effect on cell viability. Dex downregulated CRNDE expression, whereas NBIF upregulated CRNDE. Overexpressed CRNDE and NBIF reversed the inhibitory effects of Dex on cell viability, differentiation and levels of SOD, GSH-Px, Runx2, OCN, OPN, col-I, nuclear Nrf2, HO-1 and NQO1 while reversing the promoting effect of Dex on apoptosis and the levels of ROS, MDA, LDH and cytoplasm Nrf2 in MC-3T3-E1 cells, respectively, but shCRNDE further reversed the effects of NBIF in MC-3T3-E1 cells. NBIF protected osteoblasts from Dex-induced oxidative stress by upregulating the CRNDE-mediated Nrf2/HO-1 signaling pathway.