Thymoma-associated autoimmune encephalitis with positive Titin antibodies: A case report.

We report a case of thymoma-associated autoimmune encephalitis with positive Titin antibodies. The patient had cognitive dysfunction, psychiatric symptoms and symptomatic epilepsy. PET-CT indicated space-occupied lesion at the thoracic entrance. The patient was diagnosed with paraneoplastic autoimmune encephalitis. After immunotherapy, his condition improved and underwent thymectomy. Pathology revealed type A thymoma. The patient recurred 10 days after the operation. Thymoma is associated with AE. And Titin antibodies may be involved in the extensive immune response to antigens which the patient's thymoma ectopically expressed. This case reflects the complexity of the immune relationship among autoimmune encephalitis, Titin antibodises and thymoma. Titin antibody may have a certain guiding significance for the treatment and prognosis of autoimmune encephalitis.

Matrix metalloproteinase-12 cleaved fragment of titin as a predictor of functional capacity in patients with heart failure and preserved ejection fraction.

OBJECTIVES: Serum levels of matrix metalloproteinase-12 cleaved fragment of titin (TIM), a novel circulatory biomarker specific for cardiac titin degradation, has emerged as a potential biomarker in cardiovascular diseases. In this work, we aimed to evaluate the association between TIM and maximal functional capacity assessed by the percentage of predicted peak exercise oxygen uptake (pp-peakVO2) in patients with heart failure and preserved ejection fraction (HFpEF). Design. In this post-hoc study, we included 46 stable symptomatic (New York Heart Association II-III) HFpEF patients enrolled in the TRAINING-HF study (NCT02638961). pp-peak-VO2 was calculated from baseline values. Baseline circulating levels of TIM were measured by competitive ELISA in serum from the TRAINING-HF patients. The independent association between TIM and pp-peakVO2 was evaluated by multivariate linear regression analysis. Results. The mean age of the sample was 73.8 ± 8.7 years, 56.5% were females, and 76.1% were on NYHA II. The medians of pp-peakVO2 and TIM were 60.9% (50.4-69.3), and 130.1 ng/mL (98.1-159.5), respectively. The median of NT-proBNP was 912 pg/mL (302-1826). pp-peakVO2 was significant and inversely correlated with TIM (r= -41, p = .005). In multivariate analysis, after adjusting for NYHA class, hypertension, body mass index, and glomerular filtration rate, higher TIM was significantly associated with lower pp-peak VO2 (p = .029). Conclusions. In this sample of stable and symptomatic HFpEF patients, higher serum levels of TIM identified patients with worse functional status.

Changes in Urinary Titin Fragment in Response to Different Types of Dynamic Eccentric Exercises.

The urinary level of the titin fragment has been considered a non-invasive and sensitive biomarker for muscle damage in clinical cases. However, there is little evidence regarding changes in the urinary titin fragment in response to exercise-induced muscle damage. In this study, we aimed to investigate whether the urinary titin fragment reflects the magnitude of muscle damage induced by two lower-limb eccentric exercises. In this study, healthy young male subjects performed drop jump (n=9) and eccentric ergometer exercise (n=9). Blood and urine samples were collected at various time points before and after the exercises. Although perceived muscle soreness assessed by sit-to-stand tasks was increased at 24 h and 48 h after both drop jump and the eccentric ergometer exercise groups, the pressure pain threshold was not changed. Changes of the urinary titin fragment, plasma myomesin 3 fragments, creatine kinase (CK), and myoglobin (Mb) after the eccentric exercises were increased but not statistically significant. Meanwhile, we found that the changes in the urinary titin fragment levels in response to both drop jump and the eccentric ergometer exercise were correlated with those of plasma CK and Mb levels. These results provide evidence that the urinary titin fragment level is a non-invasive biomarker reflecting the magnitude of eccentric exercise-induced muscle damage.

Cardiac magnetic resonance using late gadolinium enhancement and atrial T1 mapping predicts poor outcome in patients with atrial fibrillation after catheter ablation therapy.

To determine the pre-procedural value of different fibrotic biomarkers and comprehensive cardiac magnetic resonance (CMR) for the prediction of poor response to ablation therapy in patients with atrial fibrillation (AF). Left atrial (LA) late gadolinium enhancement (LGE) and native LA T1 relaxation times were assessed using CMR. Plasma levels of relaxin, myeloperoxidase and serum levels of matrix metalloproteinase (MMP)-mediated cardiac specific titin fragmentation and MMP-mediated type IV collagen degradation were obtained. Poor outcome was defined by the recurrence of AF during 1-year follow-up. 61 patients were included in final analysis. Twenty (32.8%) patients had recurrence of AF. Patients with a recurrence of AF had a higher percentage of LA LGE (26.7 ± 12.5% vs. 17.0 ± 7.7%; P < 0.001), higher LA T1 relaxation times (856.7 ± 112.2 ms vs. 746.8 ± 91.0 ms; P < 0.001) and higher plasma levels of relaxin (0.69 ± 1.34 pg/ml vs. 0.37 ± 0.88 pg/ml; P = 0.035). In the multivariate Cox regression analysis, poor ablation outcome was best predicted by advanced LGE stage (hazard ratio (HR):5.487; P = 0.001) and T1 relaxation times (HR:1.007; P = 0.001). Pre-procedural CMR is a valuable tool for prediction of poor response to catheter ablation therapy in patients with AF. It offers various imaging techniques for outcome prediction and might be valuable for a better patient selection prior to ablation therapy.

Inverse changes in plasma tetranectin and titin levels in patients with type 2 diabetes mellitus: a potential predictor of acute myocardial infarction?

An early intervention using biomarkers to predict acute myocardial infarction (AMI) will effectively reduce global heart attack incidence, particularly among high-risk patients with type 2 diabetes mellitus (T2DM). This study attempted to identify potential biomarkers by detecting changes in the levels of plasma proteins in T2DM patients following onset of AMI in comparison with those without AMI. Volunteer T2DM patients without AMI (control; n=10) and T2DM patients with AMI (n=10) were recruited. Plasma samples from these patients were evaluated via two-dimensional gel electrophoresis (2DE) to screen for proteins with level changes between the two groups. The abundance of spots on gel images was analyzed using Progenesis SameSpots and subjected to false discovery rate (FDR) analysis. Protein spots with statistically significant changes of at least 1.5 fold were selected for mass spectrometry (MS) analysis. Due to strong cardiac connections, tetranectin and titin were evaluated by enzymelinked immunosorbent assay (ELISA). The adjusted P-values and fold changes between the two groups resulted in identification of 34 protein spots with significantly altered abundance. Upon MS analysis, 17 plasma proteins were identified: tetranectin, titin, clusterin, haptoglobin, myosin-13, zinc fnger protein 445, DNA repair protein RAD50, serum albumin, apolipoprotein A-IV, caspase-6, aminoacyl tRNA synthase complex-interacting multifunctional protein 1, serotransferrin, retinol-binding protein 4, transthyretin, alpha-1-antitrypsin, apolipoprotein A-I and serum amyloid A. Comparable patterns of changes in tetranectin and titin between the control and AMI groups were confirmed using ELISA. In summary, tetranectin and titin in plasma appeared to be closely associated with the onset of AMI among T2DM patients and can be used as potential biomarkers for prediction of a cardiac event, though this requires validation in a prospective cohort study.

Diagnostic and clinical significance of the titin fragment in urine of Duchenne muscular dystrophy patients.

Duchenne muscular dystrophy (DMD) is a fatal progressive muscle wasting disease of childhood. Titin in sarcomere is digested by calcium dependent protease. To explore muscle damage in DMD, the urinary concentrations of the N-terminal fragment of titin were determined using a newly developed enzyme linked immune sorbent assay kit. The urinary titin concentrations were normalized to creatinine (Cr). A total of 145 urine samples were obtained at a single Japanese hospital from 113 DMD patients aged 3-29years. Normalized urinary titin concentration was 965.8±1011.9 (Mean±SD) pmol/mg Cr in patients with DMD. This was nearly 700-fold higher than healthy children (1.4±0.8pmol/mg Cr). The concentration was significantly higher in DMD than in BMD patients who had significantly higher urinary titin than normal. Urinary titin in DMD patients tended to decrease with age. The median concentration of urinary titin in the youngest (aged 3-7years) and oldest (aged ≥16years) groups was 1468.3 and 411.3pmol/mg Cr, respectively, with significant difference. Urinary concentration of titin correlated significantly with serum creatine kinase concentration, the best-known biomarker of DMD. The N-terminal fragment of titin in urine has potential as a diagnostic and clinical biomarker for DMD.

Dramatic elevation in urinary amino terminal titin fragment excretion quantified by immunoassay in Duchenne muscular dystrophy patients and in dystrophin deficient rodents.

Enzyme-linked and electrochemiluminescence immunoassays were developed for quantification of amino (N-) terminal fragments of the skeletal muscle protein titin (N-ter titin) and qualified for use in detection of urinary N-ter titin excretion. Urine from normal subjects contained a small but measurable level of N-ter titin (1.0 ± 0.4 ng/ml). A 365-fold increase (365.4 ± 65.0, P = 0.0001) in urinary N-ter titin excretion was seen in Duchene muscular dystrophy (DMD) patients. Urinary N-ter titin was also evaluated in dystrophin deficient rodent models. Mdx mice exhibited low urinary N-ter titin levels at 2 weeks of age followed by a robust and sustained elevation starting at 3 weeks of age, coincident with the development of systemic skeletal muscle damage in this model; fold elevation could not be determined because urinary N-ter titin was not detected in age-matched wild type mice. Levels of serum creatine kinase and serum skeletal muscle troponin I (TnI) were also low at 2 weeks, elevated at later time points and were significantly correlated with urinary N-ter titin excretion in mdx mice. Corticosteroid treatment of mdx mice resulted in improved exercise performance and lowering of both urinary N-ter titin and serum skeletal muscle TnI concentrations. Low urinary N-ter titin levels were detected in wild type rats (3.0 ± 0.6 ng/ml), while Dmdmdx rats exhibited a 556-fold increase (1652.5 ± 405.7 ng/ml, P = 0.002) (both at 5 months of age). These results suggest that urinary N-ter titin is present at low basal concentrations in normal urine and increases dramatically coincident with muscle damage produced by dystrophin deficiency. Urinary N-ter titin has potential as a facile, non-invasive and translational biomarker for DMD.

Clinicopathological Analysis and Multipronged Quantitative Proteomics Reveal Oxidative Stress and Cytoskeletal Proteins as Possible Markers for Severe Vivax Malaria.

In Plasmodium vivax malaria, mechanisms that trigger transition from uncomplicated to fatal severe infections are obscure. In this multi-disciplinary study we have performed a comprehensive analysis of clinicopathological parameters and serum proteome profiles of vivax malaria patients with different severity levels of infection to investigate pathogenesis of severe malaria and identify surrogate markers of severity. Clinicopathological analysis and proteomics profiling has provided evidences for the modulation of diverse physiological pathways including oxidative stress, cytoskeletal regulation, lipid metabolism and complement cascades in severe malaria. Strikingly, unlike severe falciparum malaria the blood coagulation cascade was not found to be affected adversely in acute P. vivax infection. To the best of our knowledge, this is the first comprehensive proteomics study, which identified some possible cues for severe P. vivax infection. Our results suggest that Superoxide dismutase, Vitronectin, Titin, Apolipoprotein E, Serum amyloid A, and Haptoglobin are potential predictive markers for malaria severity.

Serum proteomic profiling reveals fragments of MYOM3 as potential biomarkers for monitoring the outcome of therapeutic interventions in muscular dystrophies.

Therapy-responsive biomarkers are an important and unmet need in the muscular dystrophy field where new treatments are currently in clinical trials. By using a comprehensive high-resolution mass spectrometry approach and western blot validation, we found that two fragments of the myofibrillar structural protein myomesin-3 (MYOM3) are abnormally present in sera of Duchenne muscular dystrophy (DMD) patients, limb-girdle muscular dystrophy type 2D (LGMD2D) and their respective animal models. Levels of MYOM3 fragments were assayed in therapeutic model systems: (1) restoration of dystrophin expression by antisense oligonucleotide-mediated exon-skipping in mdx mice and (2) stable restoration of α-sarcoglycan expression in KO-SGCA mice by systemic injection of a viral vector. Following administration of the therapeutic agents MYOM3 was restored toward wild-type levels. In the LGMD model, where different doses of vector were used, MYOM3 restoration was dose-dependent. MYOM3 fragments showed lower inter-individual variability compared with the commonly used creatine kinase assay, and correlated better with the restoration of the dystrophin-associated protein complex and muscle force. These data suggest that the MYOM3 fragments hold promise for minimally invasive assessment of experimental therapies for DMD and other neuromuscular disorders.

Measurement of a MMP-2 degraded Titin fragment in serum reflects changes in muscle turnover induced by atrophy.

PURPOSE: In this study we sought to determine whether a Titin peptide fragment can serve as a clinical biomarker for changes in muscle mass. METHODS: Mass spectrometry was used to identify Titin fragment in urine. An antibody against this Titin sequence was raised and used to develop a competitive ELISA assay for measurement in serum. Rat tissue extractions in the presence or absence of a series of proteases of interest were used to identify its enzymatic origin. A rat model of dexamethasone (DEX) induced muscle atrophy and a human 56-day bed rest study with and without vibration therapy were used to assess biological and clinical relevance. RESULTS: A technically robust ELISA measuring the Titin fragment was developed against a Titin peptide fragment identified in human urine. The fragment was shown to be produced primarily by MMP-2 cleavage of Titin. In the rat muscle DEX induced atrophy model, Titin-MMP2 fragment was decreased in the beginning of DEX treatment, and then significantly increased later on during DEX administration. In the human bed rest study, the Titin-MMP2 fragment was initially decreased 11.9 (±3.7) % after 1day of bed rest, and then gradually increased ending up at a 16.4 (±4.6) % increase at day 47. CONCLUSIONS: We developed a robust ELISA measuring a muscle derived MMP-2 generated Titin degradation fragment in rat and human serum. Importantly, the fragment can be measured in serum and that these levels are related to induction of skeletal muscle atrophy.

A pilot study of muscle plasma protein changes after exercise.

INTRODUCTION: Creatine kinase (CK) and myoglobin (Mb) do not possess all good qualities as biomarkers of skeletal muscle damage. We investigated the utility of troponin I (TnI) and telethonin (Tcap) as markers and examined their temporal profiles after skeletal muscle damage. METHODS: Plasma profiles were measured before and after exercise in 3 groups: subjects affected by either Becker muscular dystrophy or McArdle disease, and healthy subjects. RESULTS: Mb and TnI appeared early in the blood, and the increase of TnI was only observed in patients with muscle disease. The CK increase was more delayed in plasma. Tcap was not detectable at any time. CONCLUSIONS: Our results suggest that TnI is a marker of more severe damage signifying sarcomeric damage, and it could therefore be an important supplement to CK and Mb in clinical practice. Tcap is not useful as a marker for skeletal muscle damage.