Proteomic analysis of the extracellular matrix in idiopathic pes equinovarus

Fibrosis and expression of extracellular matrix proteins in human interventricular septum in aortic valve stenosis and regurgitation

Valvular heart disease leads to ventricular pressure and/or volume overload. Pressure overload leads to fibrosis, which might regress with its resolution, but the limits and details of this reverse remodeling are not known. To gain more insight into the extent and nature of cardiac fibrosis in valve disease, we analyzed needle biopsies taken from the interventricular septum of patients undergoing surgery for valve replacement focusing on the expression and distribution of major extracellular matrix protein involved in this process. Proteomic analysis performed using mass spectrometry revealed an excellent correlation between the expression of collagen type I and III, but there was little correlation with the immunohistochemical staining performed on sister sections, which included antibodies against collagen I, III, fibronectin, sarcomeric actin, and histochemistry for wheat germ agglutinin. Surprisingly, the immunofluorescence intensity did not correlate significantly with the gold standard for fibrosis quantification, which was performed using Picrosirius Red (PSR) staining, unless multiplexed on the same tissue section. There was also little correlation between the immunohistochemical markers and pressure gradient severity. It appears that at least in humans, the immunohistochemical pattern of fibrosis is not clearly correlated with standard Picrosirius Red staining on sister sections or quantitative proteomic data, possibly due to tissue heterogeneity at microscale, comorbidities, or other patient-specific factors. For precise correlation of different types of staining, multiplexing on the same section is the best approach.

Genetic Role in Recurrence of Idiopathic CTEV: A Systematic Review

Background

Congenital Talipes Equinovarus (CTEV) is a multitude of deformities involving equinus, varus, adductus, and cavus deformities. Clubfoot affects 1 in every 1000 infants born worldwide, with various incidences according to geographical areas. It has been previously hypothesized that the possible genetic role in Idiopathic CTEV (ICTEV) might have a treatment-resistant phenotype. However, the genetic involvement in recurrent ICTEV cases is yet to be determined.

Aim

To systematically review existing literature regarding the discovery of genetic involvement in recurrent ICTEV to date to further understand the etiology of relapse.

Methods

A comprehensive search was performed on medical databases, and the review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines. A comprehensive search was performed on several medical databases: PubMed (MEDLINE), Scopus, the Cochrane Library, and European PMC on May 10, 2022. We included studies reporting patients with recurring idiopathic CTEV or CTEV of unknown cause after treatment, reporting whole-genetic sequencing, whole-exome sequencing, Polymerase Chain Reaction, or Western blot analysis as methods of genetic analysis (intervention) and providing results of idiopathic CTEV genetic involvement. Non-English studies, literature reviews, and irrelevant articles were excluded. Quality and risk of bias assessments were performed using Newcastle-Ottawa Quality Assessment Scale for non-randomized studies where appropriate. The authors discussed data extracted with the primary outcome of gene(s) frequency being reported of their involvement in recurrent ICTEV cases.

Results

Three pieces of literature were included in this review. Two studies analyzed the genetic involvement in CTEV occurrence, while one analyzed the protein types found.

Discussion

With included studies of less than five, we could not perform other forms of analysis apart from qualitatively.

Conclusion

The rarity of literature exploring the genetic etiology of recurrent ICTEV cases has been reflected in this systematic review, giving opportunities for future research.

Regulation of COL1A2, AKT3 genes, and related signaling pathway in the pathology of congenital talipes equinovarus

Congenital talipes equinovarus (CTEV) is one of the most common congenital limb defects in children, which is a multifactorial and complex disease that associates with many unknown genetic, social-demographic, and environmental risk factors. Emerging evidence proved that gene expression or mutation might play an important role in the occurrence and development of CTEV. However, the underlying reasons and involved mechanisms are still not clear. Herein, to probe the potential genes and related signaling pathways involved in CTEV, we first identified the differentially expressed genes (DEGs) by mRNA sequencing in pediatric patients with CTEV compared with normal children. The gene of COL1A2 was upregulated, and AKT3 was downregulated at the transcriptional level. Western blot and quantitative polymerase chain reaction (qRT-PCR) results also showed that the expression of COL1A2 in CTEV was enhanced, and the AKT3 was decreased. Furthermore, the COL1A2 Knock-in (+COL1A2) and AKT3 Knock-out (-AKT3) transgenic mice were used to verify the effects of these two genes in the CTEV, and the results of which showed that both COL1A2 and AKT3 were closely related to the CTEV. We also investigated the effect of the PI3K-AKT3 signaling pathway in CTEV by measuring the relative expression of several key genes using Western blot and qRT-PCR. In line with the Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis data, the PI3K-AKT3 signaling pathway might play a potentially important role in the regulation of pathological changes of CTEV. This study will provide new ideas for the mechanism investigation and prenatal diagnosis of CTEV.

Increased Collagen Crosslinking in Stiff Clubfoot Tissue: Implications for the Improvement of Therapeutic Strategies

Congenital clubfoot is a complex musculoskeletal deformity, in which a stiff, contracted tissue forms in the medial part of the foot. Fibrotic changes are associated with increased collagen deposition and lysyl oxidase (LOX)-mediated crosslinking, which impair collagen degradation and increase the tissue stiffness. First, we studied collagen deposition, as well as the expression of collagen and the amount of pyridinoline and deoxypyridinoline crosslinks in the tissue of relapsed clubfoot by immunohistochemistry, real-time PCR, and enzyme-linked immunosorbent assay (ELISA). We then isolated fibroblast-like cells from the contracted tissue to study the potential inhibition of these processes in vitro. We assessed the effects of a LOX inhibitor, β-aminopropionitrile (BAPN), on the cells by a hydroxyproline assay, ELISA, and Second Harmonic Generation imaging. We also evaluated the cell-mediated contraction of extracellular matrix in 3D cell-populated collagen gels. For the first time, we have confirmed significantly increased crosslinking and excessive collagen type I deposition in the clubfoot-contracted tissue. We successfully reduced these processes in vitro in a dose-dependent manner with 10–40 µg/mL of BAPN, and we observed an increasing trend in the inhibition of the cell-mediated contraction of collagen gels. The in vitro inhibitory effects indicate that BAPN has good potential for the treatment of relapsed and resistant clubfeet.

Minoxidil decreases collagen I deposition and tissue-like contraction in clubfoot-derived cells: a way to improve conservative treatment of relapsed clubfoot?

AIM

Clubfoot is a congenital deformity affecting the musculoskeletal system, resulting in contracted and stiff tissue in the medial part of the foot. Minoxidil (MXD) has an inhibitory effect on lysyl hydroxylase, which influences the quality of extracellular matrix crosslinking, and could therefore be used to reduce the stiffness and to improve the flexibility of the tissue. We assessed the in vitro antifibrotic effects of minoxidil on clubfoot-derived cells.

METHODS

Cell viability and proliferation were quantified by xCELLigence, MTS, and LIVE/DEAD assays. The amount of collagen I deposited into the extracellular matrix was quantified using immunofluorescence with subsequent image segmentation analysis, hydroxyproline assay, and Second Harmonic Generation imaging. Extracellular matrix contraction was studied in a 3D model of cell-populated collagen gel lattices.

RESULTS

MXD concentrations of 0.25, 0.5, and 0.75 mM inhibited the cell proliferation in a concentration-dependent manner without causing a cytotoxic effect. Exposure to ≥0.5 mM MXD resulted in a decrease in collagen type I accumulation after 8 and 21 days in culture. Changes in collagen fiber assembly were observed by immunofluorescence microscopy and nonlinear optical microscopy (second harmonic generation). MXD also inhibited the contraction of cell-populated collagen lattices (0.5 mM by 22%; 0.75 mM by 28%).

CONCLUSIONS

Minoxidil exerts an in vitro inhibitory effect on the cell proliferation, collagen accumulation, and extracellular matrix contraction processes that are associated with clubfoot fibrosis. This study provides important preliminary results demonstrating the potential relevance of MXD for adjuvant pharmacological therapy in standard treatment of relapsed clubfoot.

Accelerated in vitro recellularization of decellularized porcine pericardium for cardiovascular grafts

An ideal decellularized allogenic or xenogeneic cardiovascular graft should be capable of preventing thrombus formation after implantation. The antithrombogenicity of the graft is ensured by a confluent endothelial cell layer formed on its surface. Later repopulation and remodeling of the scaffold by the patient's cells should result in the formation of living autologous tissue. In the work presented here, decellularized porcine pericardium scaffolds were modified by growing a fibrin mesh on the surface and inside the scaffolds, and by attaching heparin and human vascular endothelial growth factor (VEGF) to this mesh. Then the scaffolds were seeded with human adipose tissue-derived stem cells (ASCs). While the ASCs grew only on the surface of the decellularized pericardium, the fibrin-modified scaffolds were entirely repopulated in 28 d, and the scaffolds modified with fibrin, heparin and VEGF were already repopulated within 6 d. Label free mass spectrometry revealed fibronectin, collagens, and other extracellular matrix proteins produced by ASCs during recellularization. Thin layers of human umbilical endothelial cells were formed within 4 d after the cells were seeded on the surfaces of the scaffold, which had previously been seeded with ASCs. The results indicate that an artificial tissue prepared by in vitro recellularization and remodeling of decellularized non-autologous pericardium with autologous ASCs seems to be a promising candidate for cardiovascular grafts capable of accelerating in situ endothelialization. ASCs resemble the valve interstitial cells present in heart valves. An advantage of this approach is that ASCs can easily be collected from the patient by liposuction.

A novel mutation in the COL12A1 gene

Mutations in collagen XII have been recently described to cause modifications in the connective tissue which phenotypic demonstration resembles that of collagen VI related myopathies. We describe a Caucasian 14-year old girl who complained to her doctor about not being able to practice schools' sports due to recurrent clavicle dislocation when trying to throw a ball. In addition, when questioned, she also reported a notion of lower strength in the upper limbs when compared to same age peers. Based on the clinical exam performed, a joint hypermobility with a slight reduction of the muscular strength of the upper limbs diagnosis was noted. Targeted sequencing identified a heterozygous missense mutation in COL12A1 - c.8336G > A (p. Arg2779His). Algorithms developed to predict the effect of the changes on the protein structure and function do not agree on the potential impact of this modification. This case shows the importance to consider collagen XII-related disorders when in presence of patients with an overlapping phenotype with both muscle and connective tissue abnormalities, once mutations in collagen VI have been excluded.

Integrated bioinformatics analysis of potential pathway biomarkers using abnormal proteins in clubfoot

Background

As one of the most common major congenital distal skeletal abnormalities, congenital talipes equinovarus (clubfoot) affects approximately one in one thousandth newborns. Although several etiologies of clubfoot have been proposed and several genes have been identified as susceptible genes, previous studies did not further explore signaling pathways and potential upstream and downstream regulatory networks. Therefore, the aim of the present investigation is to explore abnormal pathways and their interactions in clubfoot using integrated bioinformatics analyses.

Methods

KEGG, gene ontology (GO), Reactome (REAC), WikiPathways (WP) or human phenotype ontology (HP) enrichment analysis were performed using WebGestalt, g:Profiler and NetworkAnalyst.

Results

A large number of signaling pathways were enriched e.g. signal transduction, disease, metabolism, gene expression (transcription), immune system, developmental biology, cell cycle, and ECM. Protein-protein interactions (PPIs) and gene regulatory networks (GRNs) analysis results indicated that extensive and complex interactions occur in these proteins, enrichment pathways, and TF-miRNA coregulatory networks. Transcription factors such as SOX9, CTNNB1, GLI3, FHL2, TGFBI and HOXD13, regulated these candidate proteins.

Conclusion

The results of the present study supported previously proposed hypotheses, such as ECM, genetic, muscle, neurological, skeletal, and vascular abnormalities. More importantly, the enrichment results also indicated cellular or immune responses to external stimuli, and abnormal molecular transport or metabolism may be new potential etiological mechanisms of clubfoot.

Comparison of enzymatic activities and proteomic profiles of Butyrivibrio fibrisolvens grown on different carbon sources

Background

The rumen microbiota is one of the most complex consortia of anaerobes, involving archaea, bacteria, protozoa, fungi and phages. They are very effective at utilizing plant polysaccharides, especially cellulose and hemicelluloses. The most important hemicellulose decomposers are clustered with the genus Butyrivibrio. As the related species differ in their range of hydrolytic activities and substrate preferences, Butyrivibrio fibrisolvens was selected as one of the most effective isolates and thus suitable for proteomic studies on substrate comparisons in the extracellular fraction. The B. fibrisolvens genome is the biggest in the butyrivibria cluster and is focused on “environmental information processing” and “carbohydrate metabolism”.

Methods

The study of the effect of carbon source on B. fibrisolvens 3071 was based on cultures grown on four substrates: xylose, glucose, xylan, xylan with 25% glucose. The enzymatic activities were studied by spectrophotometric and zymogram methods. Proteomic study was based on genomics, 2D electrophoresis and nLC/MS (Bruker Daltonics) analysis.

Results

Extracellular β-endoxylanase as well as xylan β-xylosidase activities were induced with xylan. The presence of the xylan polymer induced hemicellulolytic enzymes and increased the protein fraction in the interval from 40 to 80 kDa. 2D electrophoresis with nLC/MS analysis of extracellular B. fibrisolvens 3071 proteins found 14 diverse proteins with significantly different expression on the tested substrates.

Conclusion

The comparison of four carbon sources resulted in the main significant changes in B. fibrisolvens proteome occurring outside the fibrolytic cluster of proteins. The affected proteins mainly belonged to the glycolysis and protein synthesis cluster.

Electronic supplementary material

The online version of this article (10.1186/s12953-019-0150-3) contains supplementary material, which is available to authorized users.

Novel contribution to clubfoot pathogenesis: The possible role of extracellular matrix proteins

Idiopathic pes equinovarus (clubfoot) is a congenital deformity of the feet and lower legs. Clubfoot belongs to a group of fibro-proliferative disorders but its origin remains unknown. Our study aimed to achieve the first complex proteomic comparison of clubfoot contracted tissue of the foot (medial side; n = 16), with non-contracted tissue (lateral side; n = 13). We used label-free mass spectrometry quantification and immunohistochemistry. Seven proteins were observed to be significantly upregulated in the medial side (asporin, collagen type III, V, and VI, versican, tenascin-C, and transforming growth factor beta induced protein) and four in the lateral side (collagen types XII and XIV, fibromodulin, and cartilage intermediate layer protein 2) of the clubfoot. Comparison of control samples from cadavers brought only two different protein concentrations (collagen types I and VI). We also revealed pathological calcification and intracellular positivity of transforming growth factor beta only in the contracted tissue of clubfoot. Most of the 11 differently expressed proteins are strongly related to the extracellular matrix architecture and we assume that they may play specific roles in the pathogenesis of this deformity. These proteins seem to be promising targets for future investigations and treatment of this disease. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

The congenital clubfoot - immunohistological analysis of the extracellular matrix

Purpose

Congenital clubfoot is one of the most common limb disorders in humans and its etiology is still unclear. In order to better understand the pathogenesis of patients with primary clubfoot, we examined whether there are quantitative changes in the extracellular matrix (ECM; based on common interstitial collagens [C] like CI and CIII, microfilamentous collagens like CVI, noncollagenous proteins like undulin, and enzymes like matrixmetalloproteinase [MMP]-2 and tissue inhibitor of matrixmetalloproteinase [TIMP]-2 that are known to play a role in fibrogenesis and fibrolysis) of muscles involved in the foot deformity of patients with primary clubfoot corresponding to fibrosis.

Patients and methods

Thirty patients (age ranging from 4 months to 5 years and 7 months) with primary clubfoot were examined (23 male and 7 female patients), among whom 18 patients were affected on one side and 12 affected on both sides. Twenty-five biopsies were taken during the first operative foot correction (Crawford-McKay) and 5 in the context of relapses. Muscle biopsies were taken from the muscles involved in the defect (Musculus [M.] gastrocnemius and M. tibialis anterior) and from the M. vastus lateralis of the M. quadriceps femoris, which were treated as healthy comparison muscles. Quantitative analysis of the components of the ECM was performed using a computer-assisted fibrosis measurement of the immunohistochemically processed tissue samples.

Results

We found higher values for M. gastrocnemius for CI, CIII, CVI and undulin in comparison with M. vastus lateralis. However, values for TIMP-2 were reduced. We found no significant differences for the components of M. tibialis anterior and M. vastus lateralis. There were no quantitative differences between male and female or between patients affected on one side and both sides. In patients who underwent relapse surgery, CI, CIII, CVI, and undulin of the gastrocnemius were significantly higher, while TIMP-2 was significantly lower.

Conclusion

In the present study, we found manifest fibrosis in gastrocnemius due to quantitative changes in the ECM. In contrast to other studies, we found increasing fibrosis not just in contracted tissues but also in the muscle itself. Further studies are needed to clarify whether these changes are primarily responsible for the malfunction or whether they occur secondarily in the consequence of the dysfunction.

The etiology of idiopathic congenital talipes equinovarus: a systematic review

Background

Also known as clubfoot, idiopathic congenital talipes equinovarus (ICTEV) is the most common pediatric deformity and occurs in 1 in every 1000 live births. Even though it has been widely researched, the etiology of ICTEV remains poorly understood and is often described as being based on a multifactorial genesis. Genetic and environmental factors seem to have a major role in the development of this disease. Thus, the aim of this review is to analyze the available literature to document the current evidence on ICTEV etiology.

Methods

The literature on ICTEV etiology was systematically reviewed using the following inclusion criteria: studies of any level of evidence, reporting clinical or preclinical results, published in the last 20 years (1998–2018), and dealing with the etiology of ICTEV.

Results

A total of 48 articles were included. ICTEV etiology is still controversial. Several hypotheses have been researched, but none of them are decisive. Emerging evidence suggests a role of several pathways and gene families associated with limb development (HOX family; PITX1-TBX4), the apoptotic pathway (caspases), and muscle contractile protein (troponin and tropomyosin), but a major candidate gene has still not been identified. Strong recent evidence emerging from twin studies confirmed major roles of genetics and the environment in the disease pathogenesis.

Conclusions

The available literature on the etiology of ICTEV presents major limitations in terms of great heterogeneity and a lack of high-profile studies. Although many studies focus on the genetic background of the disease, there is lack of consensus on one or multiple targets. Genetics and smoking seem to be strongly associated with ICTEV etiology, but more studies are needed to understand the complex and multifactorial genesis of this common congenital lower-limb disease.

Possible Pathogenetic Mechanisms and New Therapeutic Approaches of Pes Equinovarus

Idiopathic pes equinovarus (clubfoot) is a congenital deformity of the foot and lower leg defined as a fixation of the foot in plantar flexion, adduction, supination and varus. The deformity does not affect only the foot position, which is usually investigated by radiography, CT, micro-CT, MRI or ultrasound but logically influence the whole gait biomechanics. It is supposed, that clubfoot belongs to a group of fibroproliferative disorders whose origin and multi-hierarchical effect remain unknown. It has been suggested that fibroblasts and growth factors may be involved. To gain a more global view, direct analysis of the protein composition of extracellular matrix, a proteomic approach was used. At present two principle methods are mostly used for the treatment of clubfoot: physiotherapy and the Ponseti method. The determination of the general biological and biomechanical parameters for various regions of the clubfoot can potentially help in the understanding of the mechanisms participating on this serious anomaly and thus contribute to the development of the more efficient therapeutic approach. This review summarizes the present knowledge on the possible pathogenetic mechanisms participating in the development of the clubfoot and their possible relation to the new therapeutic approaches.

Endocardial Fibroelastosis is Secondary to Hemodynamic Alterations in the Chick Embryonic Model of Hypoplastic Left Heart Syndrome

BACKGROUND

Endocardial fibroelastosis (EFE) is a diffuse thickening of the ventricular endocardium, causing myocardial dysfunction and presenting as unexplained heart failure in infants and children. One of the postulated causes is persistent and increased wall tension in the ventricles.

RESULTS

To examine whether reduced ventricular pressure in a chick model of hypoplastic left heart syndrome (HLHS) induced by left atrial ligation (LAL) at embryonic day (ED) 4 is associated with EFE at later stages, myocardial fibrosis was evaluated by histology and immunoconfocal microscopy and mass spectrometry (MS) at ED12. Immunohistochemistry with collagen I antibody clearly showed a significant thickening of the layer of subendocardial fibrous tissue in LAL hearts, and MS proved this significant increase of collagen I. To provide further insight into pathogenesis of this increased fibroproduction, hypoxyprobe staining revealed an increased extent of hypoxic regions, normally limited to the interventricular septum, in the ventricular myocardium of LAL hearts at ED8.

CONCLUSIONS

Abnormal hemodynamic loading during heart development leads to myocardial hypoxia, stimulating collagen production in the subendocardium. Therefore, EFE in this chick embryonic model of HLHS appears to be a secondary effect of abnormal hemodynamics. Developmental Dynamics 247:509-520, 2018. © 2017 Wiley Periodicals, Inc.