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Background: Human rhinoviruses (RV), the most common triggers of acute asthma exacerbations, are considered not cytotoxic to the bronchial epithelium. Recent observations, however, have questioned this knowledge. The aim of this study was to evaluate the ability of RV to induce epithelial cytotoxicity and affect epithelial repair in-vitro. Methods: Monolayers of BEAS-2B bronchial epithelial cells, seeded at different densities were exposed to RV serotypes 1b, 5, 7, 9, 14, 16. Cytotoxicity was assessed chromatometrically. Epithelial monolayers were mechanically wounded, exposed or not to RV and the repopulation of the damaged area was assessed by image analysis. Finally epithelial cell proliferation was assessed by quantitation of proliferating cell nuclear antigen (PCNA) by flow cytometry. Results: RV1b, RV5, RV7, RV14 and RV16 were able to induce considerable epithelial cytotoxicity, more pronounced in less dense cultures, in a cell-density and dose-dependent manner. RV9 was not cytotoxic. Furthermore, RV infection diminished the self-repair capacity of bronchial epithelial cells and reduced cell proliferation. Conclusion: RV-induced epithelial cytotoxicity may become considerable in already compromised epithelium, such as in the case of asthma. The RV-induced impairment on epithelial proliferation and self-repair capacity may contribute to the development of airway remodeling. [ABSTRACT FROM AUTHOR]

Background: Human Metapneumovirus (hMPV), has been recently isolated from children with acute respiratory tract infections (RTIs), including bronchiolitis, and classified in the Pneumovirinae subfamily within the Paramyxoviridae family. Objectives: Since most bronchiolitis studies fail to detect any viral pathogen in part of the samples, we sought for the presence of hMPV in a well characterized bronchiolitis cohort. Study design: Nasal washes were obtained from 56 children admitted to the hospital for acute bronchiolitis. RNA extraction and subsequent RT-PCR were used to detect hMPV, and correlated the presence of the virus with clinical characteristics of the disease. Results and conclusions: PCR revealed the presence of hMPV in 16% of bronchiolitis cases, whereas respiratory syncytial virus (RSV; 67.9%) was the most frequently encountered viral pathogen. hMPV was identified either as a unique viral pathogen or co-existed with RSV, with whom they shared a similar seasonal distribution. There were no differences in disease characteristics, either clinical or laboratory, between bronchiolitis cases where hMPV was present and those caused by RSV or other viral pathogens.These findings suggest that hMPV is a common and important causative agent in infants with bronchiolitis, with clinical characteristics similar to that of RSV. [Copyright &y& Elsevier]

The heart's limited regenerative capacity raises the need for novel stem cell-based therapeutic approaches for cardiac regeneration. However, the use of stem cells is restrictive due to poor determination of their properties and the factors that regulate them. Here, we investigated the role of desmin, the major muscle-specific intermediate filament protein, in the characteristics and differentiation capacity of cardiac side population (CSP) and Sca1+ stem cells of adult mice. We found that desmin deficiency affects the microenvironment of the cells and leads to increased numbers of CSP but not Sca1+ cells; CSP subpopulation composition is altered, the expression of the senescence marker p16INK4a in Sca1+ cells is increased, and early cardiomyogenic commitment is impaired. Specifically, we found that mRNA levels of the cardiac transcription factors Mef2c and Nkx2.5 were significantly reduced in des−/− CSP and Sca1+ cells, while differentiation of CSP and Sca1+ cells demonstrated that in the absence of desmin, the levels of Nkx2.5, Mef2c, Tnnt2, Hey2, and Myh6 mRNA are differentially affected. Thus, desmin deficiency restricts the regenerative potential of CSP and Sca1+ cells, both directly and indirectly through their microenvironment. [ABSTRACT FROM AUTHOR]

Galectin-3, a biomarker for heart failure (HF), has been associated with myocardial fibrosis. However, its causal involvement in HF pathogenesis has been questioned in certain models of cardiac injury-induced HF. To address this, we used desmin-deficient mice (des−/−), a model of progressive HF characterized by cardiomyocyte death, spontaneous inflammatory responses sustaining fibrosis, and galectin-3 overexpression. Genetic ablation or pharmacological inhibition of galectin-3 led to improvement of cardiac function and adverse remodeling features including fibrosis. Over the course of development of des−/− cardiomyopathy, monitored for a period of 12 months, galectin-3 deficiency specifically ameliorated the decline in systolic function accompanying the acute inflammatory phase (4-week-old mice), whereas a more pronounced protective effect was observed in older mice, including the preservation of diastolic function. Interestingly, the cardiac repair activities during the early inflammatory phase were restored under galectin-3 deficiency by increasing the proliferation potential and decreasing apoptosis of fibroblasts, while galectin-3 absence modulated macrophage–fibroblast coupled functions and suppressed both pro-fibrotic activation of cardiac fibroblasts and pro-fibrotic gene expression in the des−/− heart. In addition, galectin-3 also affected the emphysema-like comorbid pathology observed in the des−/− mice, as its absence partially normalized lung compliance. Collectively galectin-3 was found to be causally involved in cardiac adverse remodeling, inflammation, and failure by affecting functions of cardiac fibroblasts and macrophages. In concordance with this role, the effectiveness of pharmacological inhibition in ameliorating cardiac pathology features establishes galectin-3 as a valid intervention target for HF, with additive benefits for treatment of associated comorbidities, such as pulmonary defects. Schematic illustrating top to bottom, the detrimental role of galectin-3 (Gal3) in heart failure progression: desmin deficiency-associated spontaneous myocardial inflammation accompanying cardiac cell death (reddish dashed border) is characterized by infiltration of macrophages (round cells) and up-regulation of Lgals3 (encoding secretable galectin-3, green) and detrimental macrophage-related genes (Ccr2 and Arg1). In this galectin-3-enriched milieu, the early up-regulation of profibrotic gene expression (Tgfb1, Acta2, Col1a1), in parallel to the suppression of proliferative activities and a potential of senescence induction by cardiac fibroblasts (spindle-like cells), collectively promote des−/− cardiac fibrosis and dysfunction establishing heart failure (left panel). Additionally, galectin-3+ macrophage-enrichment accompanies the development of emphysema-like lung comorbidities. In the absence of galectin-3 (right panel), the effect of macrophage–fibroblast dipole and associated events are modulated (grey color depicts reduced expression or activities) leading to attenuated cardiac pathology in the des−/−Lgals3−/− mice. Pulmonary comorbidities are also limited. [ABSTRACT FROM AUTHOR]

Inflammation may contribute to disease progression in arrhythmogenic cardiomyopathy (ACM). However, its role in this process is unresolved. Our goal was to delineate the pathogenic role of the complement system in a new animal model of ACM and in human disease. Using cardiac histology, echocardiography, and electrocardiography, we have demonstrated that the desmin-null mouse (Des-/-) recapitulates most of the pathognomonic features of human ACM. Massive complement activation was observed in the Des-/- myocardium in areas of necrotic cells debris and inflammatory infiltrate. Analysis of C5aR-/-Des-/- double-null animals and a pharmaceutical approach using a C5a inhibitor were used to delineate the pathogenic role of the complement system in the disease progression. Our findings indicate that inhibiting C5aR (CD88) signaling improves cardiac function, histopathology, arrhythmias, and survival after endurance. Containment of the inflammatory reaction at the initiation of cardiac tissue injury (2–3 weeks of age), with consequently reduced myocardial remodeling and the absence of a direct long-lasting detrimental effect of C5a–C5aR signaling on cardiomyocytes, could explain the beneficial action of C5aR ablation in Des-/- cardiomyopathy. We extend the relevance of these findings to human pathophysiology by showing for the first time significant complement activation in the cardiac tissues of patients with ACM, thus suggesting that complement modulation could be a new therapeutic target for ACM. [ABSTRACT FROM AUTHOR]

Intermediate filaments are major components of the cytoskeleton. Desmin and synemin, cytoplasmic intermediate filament proteins and A-type lamins, nuclear intermediate filament proteins, play key roles in skeletal and cardiac muscle. Desmin, encoded by the DES gene (OMIM *125660) and A-type lamins by the LMNA gene (OMIM *150330), have been involved in striated muscle disorders. Diseases include desmin-related myopathy and cardiomyopathy (desminopathy), which can be manifested with dilated, restrictive, hypertrophic, arrhythmogenic, or even left ventricular non-compaction cardiomyopathy, Emery–Dreifuss Muscular Dystrophy (EDMD2 and EDMD3, due to LMNA mutations), LMNA-related congenital Muscular Dystrophy (L-CMD) and LMNA-linked dilated cardiomyopathy with conduction system defects (CMD1A). Recently, mutations in synemin (SYNM gene, OMIM *606087) have been linked to cardiomyopathy. This review will summarize clinical and molecular aspects of desmin-, lamin- and synemin-related striated muscle disorders with focus on LMNA and DES-associated clinical entities and will suggest pathogenetic hypotheses based on the interplay of desmin and lamin A/C. In healthy muscle, such interplay is responsible for the involvement of this network in mechanosignaling, nuclear positioning and mitochondrial homeostasis, while in disease it is disturbed, leading to myocyte death and activation of inflammation and the associated secretome alterations. [ABSTRACT FROM AUTHOR]

Fibrosis is a complex and multifactorial process, affecting the structure and compromising the function of several organs. Among those, renal fibrosis is an important pathological change, eventually leading to renal failure. Proteomic analysis of the renal parenchyma in the well-established rat model of unilateral ureteral obstruction (UUO model) suggested that transgelin was up-regulated during the development of fibrosis. Transgelin up-regulation was confirmed both at the protein and at the mRNA level. It was observed that at early stages of fibrosis transgelin was mainly expressed in the interstitial compartment and, more specifically, in cells surrounding the glomeruli. Subsequently, it was confirmed that transgelin expressing cells were activated fibroblasts, based on their extensive co-expression of α-SMA and their complete lack of co-distribution with markers of other cell types (endothelial, epithelial and cells of the immune system). These periglomerular fibroblasts exhibited staining for transgelin mainly cytoplasmic but occasionally nuclear as well. In addition, transgelin expression in periglomerular fibroblasts was absent in renal fibrosis developed in a hypertensive model, compared to the UUO model. Promoter analysis indicated that there are several conserved motifs for transcription factor binding. Among those, Kruppel-like factor 6 was found to be up-regulated in transgelin positive periglomerular activated fibroblasts, suggesting a possible involvement in the mechanism of transgelin up-regulation. These data strongly suggest that transgelin is up-regulated in the obstructive nephropathy and could be used as a novel marker for renal fibrosis in the future. [ABSTRACT FROM AUTHOR]

Abstract: Intermediate filaments (IFs) play a key role in the integration of structure and function of striated muscle, primarily by mediating mechanochemical links between the contractile apparatus and mitochondria, myonuclei, the sarcolemma and potentially the vesicle trafficking apparatus. Linkage of all these membranous structures to the contractile apparatus, mainly through the Z-disks, supports the integration and coordination of growth and energy demands of the working myocyte, not only with force transmission, but also with de novo gene expression, energy production and efficient protein and lipid trafficking and targeting. Desmin, the most abundant and intensively studied muscle intermediate filament protein, is linked to proper costamere organization, myoblast and stem cell fusion and differentiation, nuclear shape and positioning, as well as mitochondrial shape, structure, positioning and function. Similar links have been established for lysosomes and lysosome-related organelles, consistent with the presence of widespread links between IFs and membranous structures and the regulation of their fusion, morphology and stabilization necessary for cell survival. [Copyright &y& Elsevier]

Since pronounced differences exist between the fetal and adult repair processes, we studied the proliferative response of skin fibroblasts from these two stages to transforming growth factor-β (TGF-β), a cytokine with a broad range of activities in tissue repair. Here, we present evidence that TGF-β inhibits fetal human skin fibroblasts, while it is stimulatory for adult ones. This proliferative effect of TGF-β was found to be concentration- dependent, but isoform-independent. Furthermore, even a transient exposure of the cells to this growth factor was sufficient to exert its stimulatory or inhibitory action. Accordingly, we have studied the immediate responses provoked by TGF-β in major signaling pathways, and we have found that it induces a rapid activation of the SMAD pathway, i.e., phosphorylation and nuclear translocation of SMAD2, followed by dephosphorylation, most probably due to degradation by the proteasome. However, similar intensity and kinetics of this activation have been observed in both fetal and adult fibroblasts. On the other hand, curcumin, a natural product with wound healing properties that inhibits several intracellular signaling pathways, was found to completely abrogate the inhibitory effect of TGF-β1 on human fetal skin fibroblasts, without affecting the stimulatory action on fibroblasts from adult donors. In conclusion, there is a major radical in the proliferative response of fetal and adult human skin fibroblasts to TGF-β, possibly reflecting the different repair strategies followed in these two stages of development. [ABSTRACT FROM AUTHOR]