Skeletal muscles control posture, mobility and strength, and influence whole-body metabolism. Muscles are built of different types of myofibers, each having specific metabolic, molecular, and... Show moreSkeletal muscles control posture, mobility and strength, and influence whole-body metabolism. Muscles are built of different types of myofibers, each having specific metabolic, molecular, and contractile properties. Fiber classification is, therefore, regarded the key for understanding muscle biology, (patho-) physiology. The expression of three myosin heavy chain (MyHC) isoforms, MyHC-1, MyHC-2A, and MyHC-2X, marks myofibers in humans. Typically, myofiber classification is performed by an eye-based histological analysis. This classical approach is insufficient to capture complex fiber classes, expressing more than one MyHC-isoform. We, therefore, developed a methodological procedure for high-throughput characterization of myofibers on the basis of multiple isoforms. The mean fluorescence intensity of the three most abundant MyHC isoforms was measured per myofiber in muscle biopsies of 56 healthy elderly adults, and myofiber classes were identified using computational biology tools. Unsupervised clustering revealed the existence of six distinct myofiber clusters. A comparison with the visual assessment of myofibers using the same images showed that some of these myofiber clusters could not be detected or were frequently misclassified. The presence of these six clusters was reinforced by RNA expressions levels of sarcomeric genes. In addition, one of the clusters, expressing all three MyHC isoforms, correlated with histological measures of muscle health. To conclude, this methodological procedure enables deep characterization of the complex muscle heterogeneity. This study opens opportunities to further investigate myofiber composition in comparative studies. Show less
The incidence of bacterial infections and sepsis, as well as the mortality risk from sepsis, is sex specific. These clinical findings have been attributed to sex differences in immune... Show moreThe incidence of bacterial infections and sepsis, as well as the mortality risk from sepsis, is sex specific. These clinical findings have been attributed to sex differences in immune responsiveness. The aim of the present study was to investigate sex differences in monocyte-derived cytokine production response upon stimulation with the gram-negative stimulus lipopolysaccharide (LPS) using cytokine data from 15 study populations. Individual data on ex vivo cytokine production response upon stimulation with LPS in whole blood were available for 4,020 subjects originating from these 15 study populations, either from the general population or from patient populations with specific diseases. Men had a stronger cytokine production response than women to LPS for tumour necrosis factor-alpha, interleukin (IL)-6, IL-12, IL-1 beta, IL-1RA, and IL-10, but not for interferon-gamma. The granulocyte-macrophage colony-stimulating factor production response was lower in men than in women. These sex differences were independent of chronological age. As men had higher monocyte concentrations, we normalized the cytokine production responses for monocyte concentration. After normalization, the sex differences in cytokine production response to LPS disappeared, except for IL-10, for which the production response was lower in men than in women. A sex-based approach to interpreting immune responsiveness is crucial. Show less
Raz, V.; Raz, Y.; Vijver, D. van de; Bindellini, D.; Putten, M. van; Akker, E. ben van den 2019
Contractile properties of myofibers are dictated by the abundance of myosin heavy chain (MyHC) isoforms. MyHC composition designates muscle function, and its alterations could unravel differential... Show moreContractile properties of myofibers are dictated by the abundance of myosin heavy chain (MyHC) isoforms. MyHC composition designates muscle function, and its alterations could unravel differential muscle involvement in muscular dystrophies and aging. Current analyses are limited to visual assessments in which myofibers expressing multiple MyHC isoforms are prone to misclassification. As a result, complex patterns and subtle alterations are unidentified. We developed a high-throughput, data-driven myofiber analysis to quantitatively describe the variations in myofibers across the muscle. We investigated alterations in myofiber composition between genotypes, 2 muscles, and 2 age groups. We show that this analysis facilitates the discovery of complex myofiber compositions and its dependency on age, muscle type, and genetic conditions.Raz, V., Raz, Y., van de Vijver, D., Bindellini, D., van Putten, M., van den Akker, E. B. High-throughput data-driven analysis of myofiber composition reveals muscle-specific disease and age-associated patterns. Show less
Molecular biomarkers emerge as an accurate diagnostic tool, but are scarce for myopathies. Lack of outcome measures sensitive to disease onset and symptom severity hamper evaluation. Cytokines are... Show moreMolecular biomarkers emerge as an accurate diagnostic tool, but are scarce for myopathies. Lack of outcome measures sensitive to disease onset and symptom severity hamper evaluation. Cytokines are circulating immunogenic molecules, and their potential as biomarkers has been exploited in the last decade. Cytokines are released from many tissues, including skeletal muscles, but their application to monitor muscle pathology is sparse. We reported that the cytokine functional group is altered in the transcriptome of Oculopharyngeal muscular dystrophy (OPMD). OPMD is a dominantly inherited, late-onset myopathy, caused by an alanine-expansion mutation in the gene encoding for Poly(A) binding protein nuclear 1 (expPABPN1). Here we investigated the hypothesis that cytokines could mark OPMD disease state. We determined cytokines levels in Vastus lateralis muscle from genetically-confirmed expPABPN1 carriers at a symptomatic or pre-symptomatic stage. We identified cytokine-related genes candidates from a transcriptome study in a mouse overexpressing mutant PABPN1. Six cytokines were found to be consistently down-regulated in OPMD Vastus lateralis muscles. Expression levels of these cytokines were highly correlated in controls, but this correlation pattern was disrupted in OPMD. The levels of these six cytokines were not altered in expPABPN1 carriers at a pre-symptomatic stage, suggesting that this group of cytokines and is a potential biomarker for muscle weakness in OPMD. Correlation pattern of expression levels could be a novel measurer for disease state. Show less
Riaz, M.; Raz, Y.; Putten, M. van; Paniagua-Soriano, G.; Krom, Y.D.; Florea, B.I.; Raz, V. 2016
Chronic muscle diseases are highly prevalent in the elderly causing severe mobility limitations, pain and frailty. The intrinsic molecular mechanisms are poorly understood due to multifactorial... Show moreChronic muscle diseases are highly prevalent in the elderly causing severe mobility limitations, pain and frailty. The intrinsic molecular mechanisms are poorly understood due to multifactorial causes, slow progression with age and variations between individuals. Understanding the underlying molecular mechanisms could lead to new treatment options which are currently limited. Shoulder complaints are highly common in the elderly, and therefore, muscles of the shoulder’s rotator cuff could be considered as a model for chronic age-associated muscle degeneration. Diseased shoulder muscles were characterized by muscle atrophy and fatty infiltration compared with unaffected shoulder muscles. We confirmed fatty infiltration using histochemical analysis. Additionally, fibrosis and loss of contractile myosin expression were found in diseased muscles. Most cellular features, including proliferation rate, apoptosis and cell senescence, remained unchanged and genome-wide molecular signatures were predominantly similar between diseased and intact muscles. However, we found down-regulation of a small subset of muscle function genes, and up-regulation of extracellular region genes. Myogenesis was defected in muscle cell culture from diseased muscles but was restored by elevating MyoD levels. We suggest that impaired muscle functionality in a specific environment of thickened extra-cellular matrix is crucial for the development of chronic age-associated muscle degeneration. Show less
Chronic muscle diseases are highly prevalent in the elderly causing severemobility limitations, pain and frailty. The intrinsic molecular mechanisms are poorlyunderstood due to multifactorial... Show moreChronic muscle diseases are highly prevalent in the elderly causing severemobility limitations, pain and frailty. The intrinsic molecular mechanisms are poorlyunderstood due to multifactorial causes, slow progression with age and variationsbetween individuals. Understanding the underlying molecular mechanisms couldlead to new treatment options which are currently limited. Shoulder complaints arehighly common in the elderly, and therefore, muscles of the shoulder’s rotator cuffcould be considered as a model for chronic age-associated muscle degeneration.Diseased shoulder muscles were characterized by muscle atrophy and fatty infiltrationcompared with unaffected shoulder muscles. We confirmed fatty infiltration usinghistochemical analysis. Additionally, fibrosis and loss of contractile myosin expressionwere found in diseased muscles. Most cellular features, including proliferation rate,apoptosis and cell senescence, remained unchanged and genome-wide molecularsignatures were predominantly similar between diseased and intact muscles.However, we found down-regulation of a small subset of muscle function genes,and up-regulation of extracellular region genes. Myogenesis was defected in musclecell culture from diseased muscles but was restored by elevating MyoD levels. Wesuggest that impaired muscle functionality in a specific environment of thickenedextra-cellular matrix is crucial for the development of chronic age-associated muscledegeneration. Show less
Raz, Y.; Henseler, J.F.; Kolk, A.; Riaz, M.; Zwaal, P. van der; Nagels, J.; ... ; Raz, V. 2015
