Spinal cord injury dysregulates fibro-adipogenic progenitors miRNAs signaling to promote neurogenic heterotopic ossifications

Neurogenic heterotopic ossifications are intramuscular bone formations developing following central nervous system injury. The pathophysiology is poorly understood and current treatments for this debilitating condition remain unsatisfying. Here we explored the role of miRNAs in a clinically relevant mouse model that combines muscle and spinal cord injury, and in patients' cells. We found an osteo-suppressive miRNAs response in injured muscle that was hindered when the spinal cord injury was associated. In isolated fibro-adipogenic progenitors from damaged muscle (cells at the origin of ossification), spinal cord injury induced a downregulation of osteo-suppressive miRNAs while osteogenic markers were overexpressed. The overexpression of selected miRNAs in patient's fibro-adipogenic progenitors inhibited mineralization and osteo-chondrogenic markers in vitro. Altogether, we highlighted an osteo-suppressive mechanism involving multiple miRNAs in response to muscle injury that prevents osteogenic commitment which is ablated by the neurologic lesion in heterotopic ossification pathogenesis. This provides new research hypotheses for preventive treatments.

Interleukin-1 Is Overexpressed in Injured Muscles Following Spinal Cord Injury and Promotes Neurogenic Heterotopic Ossification

Neurogenic heterotopic ossifications (NHOs) form in periarticular muscles after severe spinal cord (SCI) and traumatic brain injuries. The pathogenesis of NHO is poorly understood with no effective preventive treatment. The only curative treatment remains surgical resection of pathological NHOs. In a mouse model of SCI-induced NHO that involves a transection of the spinal cord combined with a muscle injury, a differential gene expression analysis revealed that genes involved in inflammation such as interleukin-1β (IL-1β) were overexpressed in muscles developing NHO. Using mice knocked-out for the gene encoding IL-1 receptor (IL1R1) and neutralizing antibodies for IL-1α and IL-1β, we show that IL-1 signaling contributes to NHO development after SCI in mice. Interestingly, other proteins involved in inflammation that were also overexpressed in muscles developing NHO, such as colony-stimulating factor-1, tumor necrosis factor, or C-C chemokine ligand-2, did not promote NHO development. Finally, using NHO biopsies from SCI and TBI patients, we show that IL-1β is expressed by CD68⁺ macrophages. IL-1α and IL-1β produced by activated human monocytes promote calcium mineralization and RUNX2 expression in fibro-adipogenic progenitors isolated from muscles surrounding NHOs. Altogether, these data suggest that interleukin-1 promotes NHO development in both humans and mice. © 2021 American Society for Bone and Mineral Research (ASBMR).

Spinal cord injury reprograms muscle fibroadipogenic progenitors to form heterotopic bones within muscles

The cells of origin of neurogenic heterotopic ossifications (NHOs), which develop frequently in the periarticular muscles following spinal cord injuries (SCIs) and traumatic brain injuries, remain unclear because skeletal muscle harbors two progenitor cell populations: satellite cells (SCs), which are myogenic, and fibroadipogenic progenitors (FAPs), which are mesenchymal. Lineage-tracing experiments using the Cre recombinase/LoxP system were performed in two mouse strains with the fluorescent protein ZsGreen specifically expressed in either SCs or FAPs in skeletal muscles under the control of the Pax7 or Prrx1 gene promoter, respectively. These experiments demonstrate that following muscle injury, SCI causes the upregulation of PDGFRα expression on FAPs but not SCs and the failure of SCs to regenerate myofibers in the injured muscle, with reduced apoptosis and continued proliferation of muscle resident FAPs enabling their osteogenic differentiation into NHOs. No cells expressing ZsGreen under the Prrx1 promoter were detected in the blood after injury, suggesting that the cells of origin of NHOs are locally derived from the injured muscle. We validated these findings using human NHO biopsies. PDGFRα⁺ mesenchymal cells isolated from the muscle surrounding NHO biopsies could develop ectopic human bones when transplanted into immunocompromised mice, whereas CD56⁺ myogenic cells had a much lower potential. Therefore, NHO is a pathology of the injured muscle in which SCI reprograms FAPs to undergo uncontrolled proliferation and differentiation into osteoblasts.

Clinical outcomes and death associated with cardiorenal syndromes. A comprehensive nationwide cohort study

Background

Cardiorenal syndromes (CRS) are associated with increased risks of all-cause and cardiovascular death, end-stage kidney disease (ESKD), myocardial infarction (MI), heart failure (HF) and ischemic stroke. Whether subtypes of CRS are more prone to develop specific complications is unclear.

Methods

This longitudinal cohort study was based on the national hospitalisation database covering hospital care from the entire French population. The analysis focused on those with at least 5 years of complete follow-up (or dead earlier) as described by others. We identified 385,687 consecutive patients hospitalized in France in 2012 who had heart failure (HF), chronic kidney disease (CKD) and/or CRS. We estimated incidence of cardiovascular and all-cause death, MI, hospitalization for HF, ischemic stroke, ESKD (chronic dialysis or transplantation). Analysis were adjusted for 1) age and sex and 2) all baseline characteristics except cardiac and renal comorbidities.

Results

Overall, 57.7% were male, 67.3% had hypertension, 31.1% had diabetes mellitus and their mean age was 75.3±13.2; 34,217 had isolated CKD, 324,141 had HF, 11,162 had acute concomitant CRS (which could be type 1, 3 or 5 CRS), 12,198 had type 2 CRS and 3,969 had type 4 CRS.

Type 2 CRS was associated with the highest 5-year incidence of all-cause (30.3/100 patient-years [29.7–30.9]) and cardiovascular (10.7 [10.4–11.1]) death and HF (46.9 [45.9–47.9]), type 4 CRS with the highest incidence of MI (2.50 [2.21–2.83]) and patients with acute CRS with the highest incidence of ischemic stroke (2.05 [1.89–2.21]). The incidence of ESKD was 7.43/100 patient-years [6.92–7.99] for type 4 and 6.31 [6.03–6.61] for type 2 CRS, 6.16 [5.88–6.45] for aCRS, 6.00 [5.87–6.14] for CKD and 1.17 [1.15–1.19] for HF.

As compared to CKD, the adjusted risk of ESKD was higher in type 4 (HR: 1.18 [1.10–1.28]) and aCRS (1.07 [1.02–1.13]) and similar for type 2 (HR: 0.99 [0.94–1.04]) CRS. The adjusted risk of all-cause and cardiovascular death and HF was higher in patients with type 2 CRS vs all other groups, and higher in aCRS and 4 CRS than isolated CKD.

Conclusion

The long-term prognosis of CRS subtypes is poor but varies widely, some CRS subtypes being more closely associated with specific complications than others.

Funding Acknowledgement

Type of funding sources: None. All-cause deathCardiovascular death

Neurogenic Heterotopic Ossifications Recapitulate Hematopoietic Stem Cell Niche Development Within an Adult Osteogenic Muscle Environment

Hematopoiesis and bone interact in various developmental and pathological processes. Neurogenic heterotopic ossifications (NHO) are the formation of ectopic hematopoietic bones in peri-articular muscles that develop following severe lesions of the central nervous system such as traumatic cerebral or spinal injuries or strokes. This review will focus on the hematopoietic facet of NHO. The characterization of NHO demonstrates the presence of hematopoietic marrow in which quiescent hematopoietic stem cells (HSC) are maintained by a functional stromal microenvironment, thus documenting that NHOs are neo-formed ectopic HSC niches. Similarly to adult bone marrow, the NHO permissive environment supports HSC maintenance, proliferation and differentiation through bidirectional signaling with mesenchymal stromal cells and endothelial cells, involving cell adhesion molecules, membrane-bound growth factors, hormones, and secreted matrix proteins. The participation of the nervous system, macrophages and inflammatory cytokines including oncostatin M and transforming growth factor (TGF)-β in this process, reveals how neural circuitry fine-tunes the inflammatory response to generate hematopoietic bones in injured muscles. The localization of NHOs in the peri-articular muscle environment also suggests a role of muscle mesenchymal cells and bone metabolism in development of hematopoiesis in adults. Little is known about the establishment of bone marrow niches and the regulation of HSC cycling during fetal development. Similarities between NHO and development of fetal bones make NHOs an interesting model to study the establishment of bone marrow hematopoiesis during development. Conversely, identification of stage-specific factors that specify HSC developmental state during fetal bone development will give more mechanistic insights into NHO.

The 2009 pandemic H1N1 influenza and indigenous populations of the Americas and the Pacific

There are few structured data available to assess the risks associated with pandemic influenza A(H1N1)v infection according to ethnic groups. In countries of the Americas and the Pacific where these data are available, the attack rates are higher in indigenous populations, who also appear to be at approximately three to six-fold higher risk of developing severe disease and of dying. These observations may be associated with documented risk factors for severe disease and death associated with pandemic H1N1 influenza infection (especially the generally higher prevalence of diabetes, obesity, asthma, chronic obstructive pulmonary disease and pregnancy in indigenous populations). More speculative factors include those associated with the risk of infection (e.g. family size, crowding and poverty), differences in access to health services and, perhaps, genetic factors. Whatever the causes, this increased vulnerability of indigenous populations justify specific immediate actions in the control of the current pandemic including primary prevention (intensified hygiene promotion, chemoprophylaxis and vaccination) and secondary prevention (improved access to services and early treatment following symptoms onset) of severe pandemic H1N1 influenza infection.

Plague outbreak in the Libyan Arab Jamahiriya

Plague is circulating regularly in localised areas worldwide, causing sporadic cases outside Africa and remains endemic or causes limited outbreaks in some African countries. Furthermore, some notable outbreaks have been reported in Asia in the last 20 years. A limited outbreak with five cases has recently been notified by the health authorities of the Libyan Arab Jamahiriya.

Plague outbreak in the Libyan Arab Jamahiriya

Plague is circulating regularly in localised areas worldwide, causing sporadic cases outside Africa and remains endemic or causes limited outbreaks in some African countries. Furthermore, some notable outbreaks have been reported in Asia in the last 20 years. A limited outbreak with five cases has recently been notified by the health authorities of the Libyan Arab Jamahiriya.

Adaptive immune responses of legumin nanoparticles

Legumin is one of the main storage proteins in the pea seeds (Pisum sativum L.) and the molecules of this protein have the capacity of binding together to form nanoparticles after aggregation and chemical cross-linkage with glutaraldehyde. The aim of this work was to study the adaptive immune response of legumin nanoparticles in rats. Following intradermal immunisation with the native protein legumin and legumin nanoparticles of about 250 nm, the humoral and cell-mediated immune responses were analysed in rats. The humoral responses against legumin and legumin nanoparticles were examined by western blot and ELISA analysis. Both techniques clearly showed that sera from rats immunised with legumin strongly expressed antibodies against this protein. On the contrary, serum samples from rats inoculated with legumin nanoparticles did not contain detectable amounts of antibodies. These results may be explained by a reduction on the antigenic epitopes of the protein induced by the glutaraldehyde used during the cross-linking step. Concerning the cell-mediated response, neither legumin nor legumin nanoparticles stimulated an immunogenic response. This absence of response of spleen lymphocytes for legumin and legumin nanoparticles may be explained by a cytostatic effect of legumin which was corroborated by the evaluation of the middle phase of cell apoptose. In fact, both legumin and legumin nanoparticles are potent inductors of a cytostatic phenomenon and showed a significant increase of the chromatin condensation (p < 0.05) as compared with control.

Properties of deamidated gluten films enzymatically cross-linked

Films were prepared at neutral pH from deamidated gluten by casting with or without enzymatic treatment by transglutaminase in the presence of various concentrations of diamines added to the film-forming solution. Variation in the glycerol/deamidated gluten ratio from 0.2 to 0.5 had a major effect on the film mechanical properties, which is characteristic of a plasticizing effect. A ratio of 0.35, producing a tensile strength of 1.14 +/- 0.12 MPa and an elongation at break of 376 +/- 62%, was chosen for most of the enzymatic modifications. The action of transglutaminase with or without the addition of external diamines induced a simultaneous increase in tensile strength and elongation at break of the films but tended to decrease the contact angle between the film surface and a water droplet. The presence of diamines in the film solution affected the elongation at break more than the tensile strength of the films. These diamines, able to react at their two extremities, probably acted as spacers between gluten proteins. The decrease in solubility was related to the formation of high molecular weight polymers in the film. The film properties were unaffected by the type of diamine added as secondary substrate in the transglutaminase reaction.

Wheat prolamine crosslinking through dityrosine formation catalyzed by peroxidases: improvement in the modification of a poorly accessible substrate by "indirect" catalysis

"Enzyme-assisted" oxidative polymerization of wheat gliadins was performed in an attempt to obtain new protein-based networks. Two plant peroxidases (soybean and horseradish) were used to induce the dimerization of tyrosine residues. The results show that tyrosines are poorly modified by these enzymes in an aqueous medium (dityrosine corresponded to 2% of the total amount of tyrosine). Two approaches were tested to overcome problems relating to accessibility to the target tyrosines: First, the efficiency of protein crosslinking via tyrosine-tyrosine aromatic ring condensation was enhanced in water when the proteins were oxidized by a fungus peroxidase (manganese-dependent peroxidase from Phanerochaete chrysosporium), which acts according to an indirect catalysis mechanism (up to 12% of the total amount of tyrosine is recovered under a dimeric form). Second, when the gliadins were dispersed in a water/dioxane (3/1) mixed solvent system, the tyrosines were more accessible on the protein surface, and similar yields were obtained with both types of peroxidase. The two types of catalysis (contact and indirect) are considered from the standpoint of the accessibility of the target residues. Enzymatic oxidations were also performed on synthetic peptides mimicking the repeatitive domains of gliadins. The results show that exposure of tyrosine to the solvent may not be sufficient to induce dityrosine formation. The mechanical properties of some films obtained from peroxidase-treated gliadins were investigated to correlate protein crosslinking with a potential application. One effect of the enzymatic treatment was to increase the tensile strength of the films. Copyright 1999 John Wiley & Sons, Inc.

Dimeric crystal structure of a Bowman-Birk protease inhibitor from pea seeds

The trypsin/chymotrypsin inhibitors from winter pea seeds (PsTI) are members of the Bowman-Birk protease inhibitor (BBPI) family. The crystal structure of the isoform PsTI-IVb was determined by molecular replacement at 2.7 A resolution using the X-ray co-ordinates of the soybean inhibitor as a search model. The inhibitor crystallized with a nearly perfect 2-fold symmetric dimer in the asymmetric unit. Although the overall structure is very similar to that seen in other BBPIs, there are notable new structural features. Unlike the previously reported X-ray structures of BBPIs, the structure of PsTI-IVb includes the C-terminal segment of the molecule. The C-terminal tail of each subunit is partly beta-stranded and interacts with the 2-fold symmetry-related subunit, forming a beta-sheet with strands A and B of this subunit. The dimer is mainly stabilized by a large internal hydrogen-bonded network surrounded by two hydrophobic links. Fluorescence anisotropy decay measurements show that residues Tyr59 and Tyr43 are mobile in the picosecond time scale with a large amplitude. The fluorescence study and a molecular model of the simultaneous binding of PsTI-IVb to porcine trypsin and bovine chymotrypsin are compatible only with a monomeric state of the functional molecule in solution.

Chemical cleavage of bovine beta-lactoglobulin by BNPS-skatole for preparative purposes: comparative study of hydrolytic procedures and peptide characterization

A comparative study of various procedures for tryptophanyl peptide bond cleavage by BNPS-skatole [2-(2-nitrophenyl)-3-methyl-3-bromoindolenine] was carried out on native and on reduced and alkylated bovine beta-lactoglobulin (BLG). The reaction yield and the composition of the derived products were studied in acetic acid, trifluoroacetic acid (TFA), and ethanol/TFA. For BNPS-skatole removal, extraction by water or ethyl ether was compared with dialysis and gel filtration. The three expected peptides (1-19, 20-61, 62-162) and incomplete cleaved fragments (1-61, 20-162) were separated and characterized by electrophoresis, reverse-phase high-performance liquid chromatography, and mass spectrometry. The highest hydrolysis yield (67.4%) occurred with native BLG cleaved in 88% acetic acid at 47 degrees C for 60 min. Subsequent water extraction and gel filtration led to total recovery of the material, but reagent elimination was only quantitative after gel filtration. Cleavage specificity was ensured by mass spectrometry and the amino acid composition of peptides 1-19 and 62-162. The chemical side reactions identified are discussed.

Properties of glutaraldehyde cross-linked vicilin nano- and microparticles

The influence of some selected factors on the properties of nano- and microparticles obtained from vicilin (storage protein from Pisum sativum L.) has been studied. These systems were prepared by coacervation followed by a cross-linking step with glutaraldehyde. Stabilized vicilin particles could be formed very rapidly after a short exposure to a low glutaraldehyde concentration. Nevertheless, particles increased in size with time of reaction and with an increase in glutaraldehyde concentration. On the other hand, the cross-linking process greatly influenced particle stability when incubated in the presence of trypsin. In this case, degradation followed a square-root-time relationship, suggesting enzymatic attack at the surface and in the interior of the matrix. The influence of the particle size on the tryptic degradation was also investigated and led to similar conclusions. Thus, microparticles showed a more rapid degradation than might be anticipated considering particle diameter alone.

Trypsin inhibitor polymorphism: multigene family expression and posttranslational modification

Trypsin inhibitors from winter pea seeds (c.v. Frilene) have been purified and shown to consist of six protease inhibitors (PSTI I, II, III, IVa, IVb, and V). Based on amino acid composition, molecular mass, and N-terminal sequence, the six inhibitors are closely related to one another and belong to the Bowman-Birk family of inhibitors. To define the relations among them, molecular mass and amino acid composition of peptides obtained from digestion with trypsin were determined. The sequence and the biosynthetic mechanism of the isoform formation have been partially resolved for four major isoforms. Two isoinhibitor forms (PSTI IVa, IVb) in pea seeds are due to expression of two distinct genes; PSTI IVa has four amino acid replacements when its sequence is compared with the sequence of PSTI IVb. Two others (PSTI I, II) result from posttranslational proteolytic cleavage of nine C-terminal residues of forms PSTI IVa and IVb, respectively.

Amino acid sequence of a Bowman-Birk proteinase inhibitor from pea seeds

Trypsin inhibitors from winter pea seeds (c.v. Frilene) have been purified by ammonium sulfate precipitation, gel filtration, and anion and cation exchange chromatography and shown to consist of six protease inhibitors (PSTI I, II, III, IVa, IVb, and V). Their molecular weights were determined by electrospray mass spectrometry as 6916, 6807, 7676, 7944, 7848 and 7844 D, respectively, and the sequences of the first 20 N-terminal amino acid residues of these six inhibitors were found to be identical. The complete amino acid sequence of PSTI IVa was determined. This protein comprises a total of 72 residues and has 14 cysteines, all involved in disulfide bridges. Comparison of the sequence of PSTI IVa with those of other leguminous Bowman-Birk type inhibitors revealed that PSTI could be classified as a group III inhibitor, closely related to Vicia faba and Vicia angustifolia inhibitors.

Structural characteristics of a globular protein investigated by X-ray photoelectron spectroscopy: comparison between a legumin film and a powdered legumin

Films of legumin, a pea protein, were deposited onto a glass support using the Langmuir-Blodgett method, at various surface pressures. XPS study of these films show that their thickness increases with the deposition pressure. At the pressure limits of films stability, the thickness values (respectively 73 and 110 A) are close to the protein dimensions. Layered at low pressure, the oblate protein stands up when pressure increases. Furthermore, XPS study shows that the orientation of the external flexible loops depends on the obtention conditions. Thus, in the case of Langmuir-Blodgett films, hydrophobic residues are turned towards the external surface, and the hydrophilic ones towards the glass substrate. But, in the opposite, when protein is obtained by lyophilization, the hydrophilic residues are orientated outsides. It seems possible to determine by XPS the nature of the residues which give to the protein its reactivity, since they are located at its external surface.

Conformational changes upon dissociation of a globular protein from pea: a Fourier transform infrared spectroscopy study

Fourier transform infrared spectroscopy shows that the secondary structure of legumin, a globular protein from pea seeds, is composed of 41% beta-sheets and 16% alpha-helices and furthermore reveals the presence of beta-turns. The conformation prediction from the analysis of the amino-acid sequence of legumin using hydrophobic cluster analysis reveals that the C-terminal part of the alpha-polypeptide is devoid of defined secondary structures, whereas the beta-polypeptide is highly ordered. Comparison with analogous 11S globulins from other plant families indicates that ordered domains are highly preserved, phenomenon that may be associated with the similarity of the quaternary structure of these proteins. The results also reveal the presence of a large hypervariable region, located at the surface of the protein, that could be at the origin of the different functional properties of the 11S type globulins. The step-by-step destruction of the quaternary oligomeric structure of the native protein is accompanied by conformational changes that depend on the dissociation conditions. Whereas acylation leads to a decrease of the alpha-helix content by 10% at the expense of the beta-sheet content, addition of sodium perchlorate results in the conversion of 10% of the protein secondary structure from beta-sheet to unordered. These observations provide further evidence of the existence of different monomeric states that differ from their secondary structure and, therefore, exhibit different surface-active properties.

Selected physico-chemical properties of succinylated legumin from pea (Pisum sativum L.)

Selected physico-chemical properties of pea legumin before and after succinylation have been investigated using isoelectric focusing, PAGE, SDS-PAGE, hydrophobicity measurements, SE-HPLC and RP-HPLC. Exhaustive succinylation shifted the I.P. of legumin from 4.75 to 3.5. The stepwise dissociation of legumin by increasing succinylation has been confirmed both by means of PAGE in a nondenaturing system, and by SE-HPLC. The results of SDS-PAGE provided evidence for the exposure of alpha-polypeptide chains in the native legumin. High succinylation resulted in a decrease of the surface hydrophobicity (S0) measured by both fluorescence probes (cis-parinaric acid and anilino-naphthalene sulfonic acid). RP-HPLC gave a response both to conformational changes and the introduced succinyl residues.

Changes of the oligomeric structure of legumin from pea (Pisum sativum L.) after succinylation

The influence of various levels of succinylation on the structure of the legumin from pea seed has been studied by the techniques of sedimentation velocity, viscometry, fluorescence and circular dichroism spectroscopy, as well as dynamic light scattering. The protein dissociates gradually into the 3S subunit forming a 7S intermediate. At a level of 75-80% succinylation, sudden unfolding of the protein occurs characterized by drastic changes in viscometric and spectroscopic properties. The fluorescence spectra point to the formation of a novel organized structure at a moderate degree of modification before the molecular unfolding takes place. The succinylated subunit was shown to have a sedimentation coefficient of 3.2S, a diffusion coefficient of 5.03 x 10(-7) cm2 . s-1 a Stokes' radius of 4.24 nm, a partial specific volume of 0.703 ml/g, an intrinsic viscosity of 0.13 dl/g, a molar mass of 52.2 kDa and a frictional ratio of 1.74.