CK-MM autoantibodies: Prevalence, immune complexes, and effect on CK clearance

The Diagnostic Value of MR IVIM and T2 Mapping in Differentiating Autoimmune Myositis From Muscular Dystrophy

RATIONALE AND OBJECTIVES

To confirm the feasibility and compare the accuracy of magnetic resonance imaging intravoxel incoherent motion (IVIM) and T2 mapping models for the differentiation of autoimmune myositis from muscular dystrophy.

MATERIALS AND METHODS

Fourty-two autoimmune myositis and 11 muscular dystrophy patients proven by diagnostic criteria were enrolled in the study. Conventional MR sequences, IVIM, and T2 mapping through the bilateral thighs were obtained as well as blood samples for all patients. IVIM and T2 mapping parameters as well as serum markers were compared between the autoimmune myositis and muscular dystrophy groups. Mann-Whitney U tests were performed for statistical analysis along with receiver operating characteristic curves. Spearman correlation coefficient models were constructed to analyze the correlation between IVIM and T2 mapping with serological parameters.

RESULTS

The intramuscular apparent diffusion coefficient, tissue diffusivity (D), perfusion fraction (f_p), and T2 relaxation time values were statistically significantly different between the autoimmune myositis and muscular dystrophy groups (p < 0.05). Pseudo diffusivity (D_p) values showed no statistical difference between the groups (p > 0.05). D parameter of IVIM sequences differentiated autoimmune and muscular dystrophy with a higher specificity of 75.60%. T2 values within the thighs were correlated with serum creatine kinase and lactate dehydrogenase levels (p < 0.05).

CONCLUSION

Thigh muscle IVIM and T2 mapping parameters are useful in differentiating autoimmune myositis from muscular dystrophy, particularly the IVIM parameters.

Monitoring the Athlete Match Response: Can External Load Variables Predict Post-match Acute and Residual Fatigue in Soccer? A Systematic Review with Meta-analysis

BACKGROUND

Monitoring athletes' external load during a soccer match may be useful to predict post-match acute and residual fatigue. This estimation would allow individual adjustments to training programs to minimize injury risk, improve well-being, and restore players' physical performance and inform the recovery process.

METHODS

Using a systematic review and meta-analysis of the literature, the aim is to determine which monitoring variables would be the strongest predictors of acute (immediately) and residual (up to 72 h) fatigue states in soccer. PubMed, SPORTDiscus, and Web of Science databases were searched (until September 2018). Studies concurrently examining soccer match-related external load metrics and subjective and/or objective measures were selected to determine pooled correlations ([Formula: see text]) with confidence intervals (CI). The quality and strength of the findings of each study were evaluated to identify overall levels of evidence.

RESULTS

Eleven studies were included (n = 165 athletes). Acute ([Formula: see text] = 0.67; 95% CI = [0.40, 0.94]) and residual (24 h post-match, [Formula: see text] = 0.54; 95% CI = [0.35, 0.65]) changes in muscle damage markers and countermovement jump peak power output (CMJ_PPO) were, with moderate to strong evidence, largely correlated with running distance above 5.5 m s^-1. No other external load metric was largely correlated with both biochemical and neuromuscular markers. For every 100-m run above 5.5 m·s^-1, CK activity measured 24 h post-match increased by 30% and CMJ_PPO decreased by 0.5%. Conversely, the total distance covered did not present any evidence of a clear relationship with any fatigue-related marker at any time-point.

CONCLUSIONS

Running distance above 5.5 m·s^-1 represents the most sensitive monitoring variable characterizing biochemical and neuromuscular responses, at least when assessed during the initial 24 h (not at 48 h/72 h) post-match recovery period. In addition, total distance covered is not sensitive enough to inform decision-making during the fatigue monitoring process.

T2 mapping in dermatomyositis/polymyositis and correlation with clinical parameters

AIM

To explore the T2-mapping signal characteristics of the thigh muscles in patients with dermatomyositis/polymyositis (DM/PM) and to investigate the correlation between thigh muscle T2 values, clinical parameters, and serum creatinine kinase (CK).

MATERIALS AND METHODS

Forty-two patients with DM/PM proven by diagnostic criteria were enrolled in the study along with 13 healthy control subjects. Both T2-mapping and conventional magnetic resonance imaging (MRI) images were obtained in the thigh musculature of all subjects. The T2 values of thigh muscles were compared between the DM/PM patients and control groups. Thirty-one DM/PM patients were evaluated with manual muscle testing (MMT) and serum CK levels. A Spearman correlation coefficient model was used to correlate the mean T2 values and clinical assessments. The Kruskal-Wallis test and receiver operating characteristic (ROC) curves were also utilised. p-Values <0.05 reflected statistical significance.

RESULTS

The T2 value of all oedematous muscles was greater on average than that of the unaffected muscles of the DM/PM patients (p<0.05) and the muscles of healthy volunteers (p<0.05). The T2 value of unaffected muscles in DM/PM patients was also greater than that of the normal muscles in healthy volunteers (p<0.05). The area under the curves (AUCs) for T2 relaxation time values was 0.72 with respective sensitivity and specificity of 72.6% and 65.4%. The mean T2 relaxation time of the 31 patients group and the MMTs (p<0.05) was correlated without serum CK levels (p>0.05).

CONCLUSION

T2 mapping is not only quantitatively used for subclinical muscle involvement in DM/PM, but also be used to demonstrate severity of damaged muscles in DM/PM.

Muscle Damage Response in Female Collegiate Athletes After Repeated Sprint Activity

Exercise-induced muscle damage (EIMD) is a well-investigated area, however there is a paucity of data surrounding the damage response in females. The aim of this study was to examine the damage responses from a sport-specific bout of repeated sprints in female athletes. Eleven well-trained females (mean ± SD; age: 22 ± 3 years; height: 166.6 ± 5.7 cm; mass: 62.7 ± 4.5 kg) in the luteal phase of the menstrual cycle completed a repeated sprint protocol designed to induce EIMD (15 × 30 m sprints). Creatine kinase, countermovement jump height, knee extensor maximal voluntary isometric contraction (MVIC) force, delayed onset muscle soreness (DOMS), 30-m sprint time, and limb girth were recorded before, after, 24, 48, and 72 hours after exercise. Creatine kinase was elevated at 24, 48, and 72 hours (p ≤ 0.05), peaking at 24 hours (+418%) and returning toward baseline at 72 hours. Countermovement jump height was reduced immediately after, 24, and 48 hours (p ≤ 0.05). Sprint performance was also negatively affected immediately after, 24, 48, and 72 hours after exercise. Muscle soreness peaked at 48 hours (p < 0.01) and remained significantly elevated at 72 hours after exercise (p < 0.01). Limb girth and MVIC did not alter over time. This study provides new information on the EIMD response in trained females after a sport-specific bout of repeated sprints. Importantly, this damage response has the potential to negatively affect performance for several days after exercise.

Biomarkers of multiorgan injury in a preclinical model of exertional heat stroke

It is likely that the pathophysiology of exertional heat stroke (EHS) differs from passive heat stroke (PHS), but this has been difficult to verify experimentally. C57Bl/6 mice were instrumented with temperature transponders and underwent 3 wk of training using voluntary and forced running wheels. An EHS group was exposed to environmental temperatures (Tenv) of 37.5, 38.5, or 39.5°C at either 30, 50, or 90% relative humidities (RH) while exercising on a forced running wheel. Results were compared with sham-matched exercise controls (EXC) and naïve controls (NC). In EHS, mice exercised in heat until they reached limiting neurological symptoms (loss of consciousness). The symptom-limited maximum core temperatures achieved were between 42.1 and 42.5°C at 50% RH. All mice that were followed for 4 days survived. Additional groups were killed at 0.5, 3, 24, and 96 h, post-EHS or -EXC. Histopathology revealed extensive damage in all regions of the small intestine, liver, and kidney. Plasma creatine kinase, blood urea nitrogen, alanine transaminase, and intestinal fatty acid binding protein-2 were significantly elevated compared with matched EXC and NC, suggesting multiple organ injury to striated muscle, kidney, liver, and intestine, respectively. EHS mice were hypoglycemic immediately following EHS but exhibited sustained hyperglycemia through 4 days. The results demonstrate unique features of survivable EHS in the mouse that included loss of consciousness, extensive organ injury, and rhabdomyolysis.

The influence of estradiol on muscle damage and leg strength after intense eccentric exercise

PURPOSE

To examine the influence of estradiol on muscle damage and leg strength after intense eccentric exercise.

METHODS

Eight men (MEN), eight normally menstruating women (WomenNM), and eight women using oral contraceptives (WomenOC) participated in this study. Subjects performed 240 maximal-effort bilateral eccentric contractions of the quadriceps muscle groups designed to elicit exercise-induced muscle damage (EiMD). Serum creatine kinase (CK), myoglobin (Mb), and fatty acid-binding protein (FABP) concentrations were measured before (pre-) EiMD, as well as 0, 6, 24, and 48 h post-EiMD. Peak isometric quadriceps torque (i.e., leg strength) was measured pre-EiMD, as well as 24 and 48 h post-EiMD.

RESULTS

The increases in CK, Mb, and FABP concentrations from pre- to post-EiMD were greater in MEN (10-fold, 15-fold, and fourfold, respectively) and WomenOC (sevenfold, 11-fold, and ninefold) compared with WomenNM (five-, six-, and threefold; p < 0.05). The decline in leg strength was about 10 % pre- to 24 h post-EiMD in all groups and decreased a further 10-15 % by 48 h post-EiMD in the MEN and WomenOC only.

CONCLUSION

Our findings suggest an important role of estradiol in blunting the muscle damage response to intense eccentric exercise and preserving muscle function after EiMD.

CKM and LILRB5 are associated with serum levels of creatine kinase

BACKGROUND

Statins (HMG-CoA reductase inhibitors) are the most prescribed class of lipid-lowering drugs for the treatment and prevention of cardiovascular disease. Creatine kinase (CK) is a commonly used biomarker to assist in the diagnosis of statin-induced myotoxicity but the normal range of CK concentrations is wide, which limits its use as a diagnostic biomarker.

METHODS AND RESULTS

We conducted a genome-wide association study of serum CK levels in 3412 statin users. Patients were recruited in Quebec, Canada, and genotyped on Illumina Human610-Quad and an iSelect panel enriched for lipid homeostasis, hypertension, and drug metabolism genes. We found a strong association signal between serum levels of CK and the muscle CK (CKM) gene (rs11559024: P=3.69×10(-16); R(2)=0.02) and with the leukocyte immunoglobulin-like receptor subfamily B member 5 (LILRB5) gene (rs2361797: P=1.96×10(-10); R(2)=0.01). Genetic variants in those 2 genes were independently associated with CK levels in statin users. Results were successfully replicated in 5330 participants from the Montreal Heart Institute Biobank in statin users for CKM (rs11559024: P=4.32×10(-16); R(2)=0.02) and LILRB5 (rs12975366 P=4.45×10(-10); R(2)=0.01) and statin nonusers (P=4.08×10(-7), R(2)=0.01; P=3.17×10(-9), R(2)=0.02, respectively).

CONCLUSIONS

This is the first genome-wide study to report on the underlying genetic determinants of CK variation in a population of statin users. We found statistically significant association for variants in the CKM and LILRB5 genes.

Migrant labor and wear-out in manual sugarcane harvesting in São Paulo, Brazil

The scope of this paper is to describe the work of manual sugarcane harvesters, assessing the nutritional behavior and body composition between the beginning and the end of the harvest. A descriptive longitudinal study was made of harvesters in Piracicaba, São Paulo, Brazil, who answered a socio-demographic questionnaire and authorized measurement of Body Mass Index, Body Fat Percentage and Arm Muscle Circumference at three stages. Creatine kinase on the skeletal isoform, C-reactive protein and plasma urea were measured at the end of the harvest. Thirty male migrant harvesters with ages ranging from 18 to 44 from the Northeast (Ceará) were assessed over a nine-month period. The workers suffered significant body fat and weight loss in the first half of the harvest. Eighteen workers had abnormal levels of creatine kinase and four - out of 24 who had donated blood - had altered urea levels. Sugarcane harvesting work causes weight and body fat loss and gains in the lean body mass index, which suffers wear-out when working on consecutive harvests. It can also cause changes in biochemical markers of chronic systemic inflammation. Further studies will make it possible to comprehend the relationships between stress, wear-out, labor longevity and health in sugarcane harvesting.

Laboratory Test Abnormalities are Common in Polymyositis and Dermatomyositis and Differ Among Clinical and Demographic Groups

Objective:

Given the difficulties regarding the interpretation of common laboratory test results in polymyositis (PM) and dermatomyositis (DM) in clinical practice, we assessed their range of abnormalities, differences among phenotypes and interrelationships in a large referral population.

Methods:

We retrospectively assessed 20 commonly measured blood laboratory tests in 620 well-defined PM/DM patients at different stages of illness and treatment to determine the frequency, range of abnormalities and correlations among clinical, gender, racial and age phenotypes.

Results:

Myositis patients at various stages of their disease showed frequent elevations of the serum activities of creatine kinase (51%), alanine aminotransferase (43%), aspartate aminotransferase (51%), lactate dehydrogenase (60%), aldolase (65%) and myoglobin levels (48%) as expected. Other frequent abnormalities, however, included elevated high white blood cell counts (36%), low lymphocyte counts (37%), low hematocrit levels (29%), low albumin levels (22%), high creatine kinase MB isoenzyme fractions (52%), high erythrocyte sedimentation rates (33%) and high IgM and IgG levels (16% and 18%, respectively). Many of these tests significantly differed among the clinical, gender, racial and age groups. Significant correlations were also found among a number of these laboratory tests, particularly in the serum activity levels of creatine kinase, the transaminases, lactate dehydrogenase and aldolase.

Conclusion:

Laboratory test abnormalities are common in PM/DM. Knowledge of the range of these expected abnormalities in different myositis phenotypes, gender and age groups and their correlations should assist clinicians in better interpretation of these test results, allow for a clearer understanding what level of abnormality warrants further evaluation for liver or other diseases, and may avoid unnecessary laboratory or other testing.

Review on autoimmune reactions in female infertility: antibodies to follicle stimulating hormone

Female fertility can be affected by diseases or dysfunctions of reproductive tract, neuroendocrine system, and immune system. Reproductive autoimmune failure can be associated with overall activation of immune system or with immune system reactions specifically directed against ovarian antigens. Majority of the antiovarian autoantibodies are directed against β-subunit of follicle stimulating hormone (anti-FSH). This paper summarizes a current clinical classification of female infertility in the context of general activation of autoimmunity and antiovarian autoimmunity by describing serum anti-FSH. The presence of naturally occurring anti-FSH in healthy women will be discussed. In addition, the putative impairment of ovarian folliculogenesis in case of increased production of those antibodies in infertile women will be characterized.

The influence of estrogen on skeletal muscle: sex matters

As women enter menopause, the concentration of estrogen and other female hormones declines. This hormonal decrease has been associated with a number of negative outcomes, including a greater incidence of injury as well as a delay in recovery from these injuries. Over the past two decades, our understanding of the protective effects of estrogen against various types of injury and disease states has grown immensely. In skeletal muscle, studies with animals have demonstrated that sex and estrogen may potentially influence muscle contractile properties and attenuate indices of post-exercise muscle damage, including the release of creatine kinase into the bloodstream and activity of the intramuscular lysosomal acid hydrolase, beta-glucuronidase. Furthermore, numerous studies have revealed an estrogen-mediated attenuation of infiltration of inflammatory cells such as neutrophils and macrophages into the skeletal muscles of rats following exercise or injury. Estrogen has also been shown to play a significant role in stimulating muscle repair and regenerative processes, including the activation and proliferation of satellite cells. Although the mechanisms by which estrogen exerts its influence upon indices of skeletal muscle damage, inflammation and repair have not been fully elucidated, it is thought that estrogen may potentially exert its protective effects by: (i) acting as an antioxidant, thus limiting oxidative damage; (ii) acting as a membrane stabilizer by intercalating within membrane phospholipids; and (iii) binding to estrogen receptors, thus governing the regulation of a number of downstream genes and molecular targets. In contrast to animal studies, studies with humans have not as clearly delineated an effect of estrogen on muscle contractile function or on indices of post-exercise muscle damage and inflammation. These inconsistencies have been attributed to a number of factors, including age and fitness level of subjects, the type and intensity of exercise protocols, and a focus on sex differences that typically involve factors and hormones in addition to estrogen. In recent years, hormone replacement therapy (HRT) or estrogen combined with exercise have been proposed as potentially therapeutic agents for postmenopausal women, as these agents may potentially limit muscle damage and inflammation and stimulate repair in this population. While the benefits and potential health risks of long-term HRT use have been widely debated, controlled studies using short-term HRT or other estrogen agonists may provide future new and valuable insights into understanding the effects of estrogen on skeletal muscle, and greatly benefit the aging female population. Recent studies with older females have begun to demonstrate their benefits.

Seven weeks of instability and traditional resistance training effects on strength, balance and functional performance

The objective of the study was to compare the effect of a 7-week unstable and stable resistance training program on measures of strength, balance, and functional performance. Forty participants were divided into unstable or stable resistance training groups. Training was conducted twice a week for 7 weeks. Pre- and post-testing measures included leg extension strength, static and dynamic balance, sit-ups, long jump, hopping test for time, shuttle run, and sprint. Results showed that there was no overall difference between unstable and stable resistance training and the training effects were independent of gender. All measures except sprint time improved with training. Interaction effects demonstrated that unstable resistance training did provide an advantage for number of sit-ups performed (p = 0.03; 8.9%) and the right leg hopping test (6.2%; p = 0.0001). This study has demonstrated that instability resistance training may be considered as effective as traditional stable resistance training for inexperienced resistance trainers. Based on the present study and the literature, instability resistance training should be incorporated in conjunction with traditional stable training to provide a greater variety of training experiences without sacrificing training benefits.

Anti-chemokine autoantibody:chemokine immune complexes activate endothelial cells via IgG receptors

Our previous studies revealed that the presence in lung fluids of anti-IL-8 autoantibody:IL-8 immune complexes is an important prognostic indicator for the development and outcome of acute lung injury (ALI)/acute respiratory distress syndrome (ARDS). Anti-IL-8:IL-8 complexes purified from lung edema fluids trigger chemotaxis of neutrophils, induce activation of these cells, and regulate their apoptosis, all via IgG receptor, FcgammaRIIa. Importantly, increased levels of FcgammaRIIa are present in lungs of patients with ARDS, where FcgammaRIIa is partially associated with anti-IL-8:IL-8 complexes. In the current study, we demonstrate the ability of anti-IL-8:IL-8 complexes to promote an inflammatory phenotype of human umbilical vein endothelial cells via interaction with FcgammaRIIa. Human umbilical vein endothelial cells cultured in the presence of the complexes become activated, as shown by increased phosphorylation of ERK, JNK, and Akt, and augmented nuclear translocation of NF-kappaB. Anti-IL-8:IL-8 complexes also up-regulate expression of intracellular adhesion molecule (ICAM)-1 on the cell surface. Furthermore, we detected increased levels of ICAM-1 on lung endothelial cells from mice in which lung injury was induced by generating immune complexes in alveolar spaces. On the other hand, ICAM-1 expression was unchanged in lungs of gamma chain-deficient mice, lacking receptors that interact with immune complexes. Moreover, in lung tissues from patients with ARDS, anti-IL-8:IL-8 complexes were associated with endothelial cells that expressed higher levels of ICAM-1. Our current findings implicate that anti-chemokine autoantibody:chemokine immune complexes, such as IL-8:IL-8 complexes, may contribute to pathogenesis of lung inflammation by inducing activation of endothelial cells through engagement of IgG receptors.

Anti-IL-8 autoantibody:IL-8 immune complexes suppress spontaneous apoptosis of neutrophils

Our previous studies demonstrated that a significant fraction of interleukin-8 (IL-8) in lung fluids from patients with acute lung injury (ALI) and the acute respiratory distress syndrome (ARDS) is associated with anti-IL-8 autoantibodies (anti-IL-8:IL-8 immune complexes). Neutrophils have been implicated in the pathogenesis of ALI/ARDS, and moreover, it is well-established that apoptosis of neutrophils is delayed in patients with ALI/ARDS. The aim of this study was, therefore, to examine the role of anti-IL-8:IL-8 immune complexes in modulating spontaneous apoptosis of normal human neutrophils. Apoptosis was assessed by evaluating morphological changes, measuring enzymatic activity of caspase-3, and determining the extent of DNA degradation. We found that samples containing anti-IL-8:IL-8 immune complexes but not samples from which these complexes were removed inhibited neutrophil apoptosis. Furthermore, the former samples or effectively anti-IL-8:IL-8 complexes induced an increase in the level of antiapoptotic protein, Bcl-X(L). In contrast, levels of proapoptotic proteins Bax and Bak were decreased in the same conditions. Activity of both caspase-3 and caspase-9 was also suppressed by anti-IL-8:IL-8 complex-containing samples. Finally, we established that IgG receptor, FcgammaRIIa, mediates antiapoptotic activity of anti-IL-8:IL-8 complexes and that the key components of the FcgammaRIIa signaling pathway, Src, Syk, PI3 kinase, and ERK, may be involved in regulation of neutrophil apoptosis by the complexes. These studies demonstrate for the first time that anti-IL-8:IL-8 immune complexes have the ability to prolong neutrophil life.