Flow cytofluorimetric analysis of anti-LRP4 (LDL receptor-related protein 4) autoantibodies in Italian patients with Myasthenia gravis

Background: Myasthenia gravis (MG) is an autoimmune disease in which 90% of patients have autoanti-bodies against the muscle nicotinic acetylcholine receptor (AChR), while autoantibodies to muscle-specific tyrosine kinase (MuSK) have been detected in half (5%) of the remaining 10%. Recently, the low-density lipoprotein receptor-related protein 4(LRP4), identified as the agrin receptor, has been recognized as a third autoimmune target in a significant portion of the double sero-negative (dSN) myasthenic individuals, with variable frequency depending on different methods and origin countries of the tested population. There is also convincing experimental evidence that anti-LRP4 autoantibodies may cause MG. Methods: The aim of this study was to test the presence and diagnostic significance of anti-LRP4 autoantibodies in an Italian population of 101 myasthenic patients (55 dSN, 23 AChR positive and 23 MuSK positive), 45 healthy blood donors and 40 patients with other neurological diseases as controls. All sera were analyzed by a cell-based antigen assay employing LRP4-transfected HEK293T cells, along with a flow cytofluorimetric detection system. Results: We found a 14.5% (8/55) frequency of positivity in the dSN-MG group and a 13% frequency of co-occurrence (3/23) in both AChR and MuSK positive patients; moreover, we report a younger female prevalence with a mild form of disease in LRP4-positive dSN-MG individuals. Conclusion: Our data confirm LRP4 as a new autoimmune target, supporting the value of including anti-LRP4 antibodies in further studies on Myasthenia gravis

Age-Related Sarcopenia: Diabetes of the Muscle?

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Flow Cytofluorimetric Analysis of Anti-LRP4 (LDL Receptor-Related Protein 4) Autoantibodies in Italian Patients with Myasthenia Gravis

Myasthenia gravis (MG) is an autoimmune disease in which 90% of patients have autoantibodies against the muscle nicotinic acetylcholine receptor (AChR), while autoantibodies to muscle-specific tyrosine kinase (MuSK) have been detected in half (5%) of the remaining 10%. Recently, the low-density lipoprotein receptor-related protein 4 (LRP4), identified as the agrin receptor, has been recognized as a third autoimmune target in a significant portion of the double sero-negative (dSN) myasthenic individuals, with variable frequency depending on different methods and origin countries of the tested population. There is also convincing experimental evidence that anti-LRP4 autoantibodies may cause MG

Association of the DNMT3B -579G>T polymorphism with risk of thymomas in patients with myasthenia gravis

Increasing evidence suggests a contribution of epigenetic processes in promoting cancer and autoimmunity. Myasthenia gravis (MG) is an autoimmune disease mediated, in approximately 80% of the patients, by antibodies against the nicotinic acetylcholine receptor (AChR+). Moreover, epithelial tumours (thymomas) are present in about 10-20% of the patients, and there is indication that changes in DNA methylation might contribute to the risk and progression of thymomas. However, the role of epigenetics in MG is still not completely clarified. In the present study we investigated if a common polymorphism (-579G>T: rs1569686) in the promoter of the DNMT3B gene coding for the DNA methyltransferase 3B, an enzyme that mediates DNA methylation, increases the risk to develop MG or MG-associated thymomas. The study polymorphism was selected based on recent reports and a literature meta-analysis suggesting association with increased risk of various types of cancer. We screened 324 AChR+ MG patients (140 males and 184 females, mean age 56.0 \ub1 16.5 years) and 735 healthy matched controls (294 males and 441 females, mean age 57.3 \ub1 15.6 years). 94 of the total MG patients had a thymoma. While there was no association with the whole cohort of MG patients, we found a statistically significant association of the DNMT3B-579T allele (OR = 1.51; 95% CI=1.1-2.1, P = 0.01) and the TT homozygous genotype (OR = 2.59; 95% CI=1.4-4.9, P = 0.006) with the risk of thymoma. No association was observed in MG patients without thymoma, even after stratification into clinical subtypes. Present results suggest that the DNMT3B-579T allele might contribute to the risk of developing thymoma in MG patients, particularly in homozygous TT subjects

A genome-wide association study of myasthenia gravis

IMPORTANCE: Myasthenia gravis is a chronic, autoimmune, neuromuscular disease characterized by fluctuating weakness of voluntary muscle groups. Although genetic factors are known to play a role in this neuroimmunological condition, the genetic etiology underlying myasthenia gravis is not well understood. OBJECTIVE: To identify genetic variants that alter susceptibility to myasthenia gravis, we performed a genome-wide association study. DESIGN, SETTING, AND PARTICIPANTS: DNA was obtained from 1032 white individuals from North America diagnosed as having acetylcholine receptor antibody–positive myasthenia gravis and 1998 race/ethnicity-matched control individuals from January 2010 to January 2011. These samples were genotyped on Illumina OmniExpress single-nucleotide polymorphism arrays. An independent cohort of 423 Italian cases and 467 Italian control individuals were used for replication. MAIN OUTCOMES AND MEASURES: We calculated P values for association between 8114394 genotyped and imputed variants across the genome and risk for developing myasthenia gravis using logistic regression modeling. A threshold P value of 5.0 × 10(−8) was set for genome-wide significance after Bonferroni correction for multiple testing. RESULTS: In the over all case-control cohort, we identified association signals at CTLA4 (rs231770; P = 3.98 × 10(−8); odds ratio, 1.37; 95% CI, 1.25–1.49), HLA-DQA1 (rs9271871; P = 1.08 × 10(−8); odds ratio, 2.31; 95% CI, 2.02 – 2.60), and TNFRSF11A (rs4263037; P = 1.60 × 10(−9); odds ratio, 1.41; 95% CI, 1.29–1.53). These findings replicated for CTLA4 and HLA-DQA1 in an independent cohort of Italian cases and control individuals. Further analysis revealed distinct, but overlapping, disease-associated loci for early- and late-onset forms of myasthenia gravis. In the late-onset cases, we identified 2 association peaks: one was located in TNFRSF11A (rs4263037; P = 1.32 × 10(−12); odds ratio, 1.56; 95% CI, 1.44–1.68) and the other was detected in the major histocompatibility complex on chromosome 6p21 (HLA-DQA1; rs9271871; P = 7.02 × 10(−18); odds ratio, 4.27; 95% CI, 3.92–4.62). Association within the major histocompatibility complex region was also observed in early-onset cases (HLA-DQA1; rs601006; P = 2.52 × 10(−11); odds ratio, 4.0; 95% CI, 3.57–4.43), although the set of single-nucleotide polymorphisms was different from that implicated among late-onset cases. CONCLUSIONS AND RELEVANCE: Our genetic data provide insights into aberrant cellular mechanisms responsible for this prototypical autoimmune disorder. They also suggest that clinical trials of immunomodulatory drugs related to CTLA4 and that are already Food and Drug Administration approved as therapies for other autoimmune diseases could be considered for patients with refractory disease

A Genome-Wide Association Study of Myasthenia Gravis

Myasthenia gravis is a chronic, autoimmune, neuromuscular disease characterized by fluctuating weakness of voluntary muscle groups. Although genetic factors are known to play a role in this neuroimmunological condition, the genetic etiology underlying myasthenia gravis is not well understood

Why Does an I.M. Immunization Work?

The skeletal muscle has been long viewed as a site of election for immunization due to the sustained stay of the antigens in this tissue. Besides a passive function during immune priming, however, recent studies have shed light on an active role of muscle cells (fibers, satellite cells, and stromal cells) in inflammatory and immune response. In this context, the chemical nature of the antigen (into tissues and cells?) and the choice of adjuvants contribute to determine the fate of the antigen itself and the resulting immune response. In particular, this applies to modern vaccine approaches that involve the use of nucleic acid to locally synthesize the protein antigen. Based on these novel concepts, the possibility of manipulating therapeutically the mechanisms of peripheral tolerance at the level of muscle tissue will be discussed in the light of the recent literature

A Study of Inflammatory/Necrosis Biomarkers in the Fracture of the Femur Treated with Proximal Femoral Nail Antirotation

Pertrochanteric fractures are common injuries in adults and source of morbidity and mortality among the elderly. Different surgical techniques were recommended for their treatment but undoubtedly they add an additional inflammatory trauma along the fracture itself. Many attempts to quantify the degree of approach-related trauma are carried out through measurements of systemic inflammatory parameters. In this study we prospectively analyzed laboratory data of 20 patients over eighty with pertrochanteric fracture of the femur treated with proximal femoral nail antirotation (PFNA). This is an excellent device for osteosynthesis because it can be easily and quickly inserted by a mini-incision providing stable fixation and early full mobilization. Serum tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), C-reactive protein (CRP), and plasma creatin kinase (CK) were evaluated 1 hour preoperatively and 24 hours postoperatively. Our results show that PFNA did not induce significant increments in serum levels of inflammatory cytokines TNF-α and IL-6; CRP was elevated preoperatively in correlation with waiting time for surgery; CRP and CK showed a significant increment in the first postoperatory day; CK increment was correlated with surgical time length. We conclude that, for the markers we analyzed, PFNA shows a low biomechanical-inflammatory profile that represents an advantage over other techniques

Disease specific enrichment of circulating let-7 family microRNA in MuSK+ myasthenia gravis.

Myasthenia gravis (MG) patients with antibodies against the muscle specific tyrosine kinase (MuSK+) have predominantly involvement of cranio-bulbar muscles and do not display thymus pathology, as do acetylcholine receptor antibody seropositive (AChR+) MG patients. In search of novel biomarkers for MuSK+ MG, we evaluated circulating serum microRNAs. Four analyzed microRNAs were specifically elevated in MuSK+ MG patient serum samples: let-7a-5p, let-7f-5p, miR-151a-3p and miR-423-5p. The circulating microRNA profile in MuSK+ MG differs from the profile previously observed in the serum of AChR+ MG, thus indicating the etiological difference between these two entities. We propose that the identified microRNAs could serve as potential serum biomarkers for MuSK+ MG