Syndecan-1 and Syndecan-4 Capture Epidermal Growth Factor Receptor Family Members and the α3ß1 Integrin Via Binding Sites in Their Ectodomains: NOVEL SYNSTATINS PREVENT KINASE CAPTURE AND INHIBIT α6ß4-INTEGRIN-DEPENDENT EPITHELIAL CELL MOTILITY.

The α6ß4 integrin is known to associate with receptor tyrosine kinases when engaged in epithelial wound healing and in carcinoma invasion and survival. Prior work has shown that HER2 associates with α6ß4 integrin and syndecan-1 (Sdc1), in which Sdc1 engages the cytoplasmic domain of the ß4 integrin subunit allowing HER2-dependent motility and carcinoma cell survival. In contrast, EGFR associates with Sdc4 and the α6ß4 integrin, and EGFR-dependent motility depends on cytoplasmic engagement of ß4 integrin with Sdc4. However, how HER2 and EGFR assimilate into a complex with the syndecans and integrin, and why kinase capture is syndecan-specific has remained unknown. In the present study, we demonstrate that HER2 is captured via a site, comprised of amino acids 210-240, in the extracellular domain of human Sdc1, and EGFR is captured via an extracellular site comprised of amino acids 87-131 in human Sdc4. Binding assays using purified recombinant proteins demonstrate that the interaction between the EGFR family members and the syndecans is direct. The α3ß1 integrin, which is responsible for the motility of the cells, is captured at these sites as well. Peptides based on the interaction motifs in Sdc1 and Sdc4, called synstatins (SSTN210-240 and SSTN87-131) competitively displace the receptor tyrosine kinase and α3ß1 integrin from the syndecan with an IC50 of 100-300 nm. The syndecans remain anchored to the α6ß4 integrin via its cytoplasmic domain, but the activation of cell motility is disrupted. These novel SSTN peptides are potential therapeutics for carcinomas that depend on these HER2- and EGFR-coupled mechanisms for their invasion and survival.

Cytoplasmic domain interactions of syndecan-1 and syndecan-4 with α6ß4 integrin mediate human epidermal growth factor receptor (HER1 and HER2)-dependent motility and survival.

Epithelial cells are highly dependent during wound healing and tumorigenesis on the α6ß4 integrin and its association with receptor tyrosine kinases. Previous work showed that phosphorylation of the ß4 subunit upon matrix engagement depends on the matrix receptor syndecan (Sdc)-1 engaging the cytoplasmic domain of the ß4 integrin and coupling of the integrin to human epidermal growth factor receptor-2 (HER2). In this study, HER2-dependent migration activated by matrix engagement is compared with migration stimulated by EGF. We find that whereas HER2-dependent migration depends on Sdc1, EGF-dependent migration depends on a complex consisting of human epidermal growth factor receptor-1 (HER1, commonly known as EGFR), α6ß4, and Sdc4. The two syndecans recognize distinct sites at the extreme C terminus of the ß4 integrin cytoplasmic domain. The binding motif in Sdc1 is QEEXYX, composed in part by its syndecan-specific variable (V) region and in part by the second conserved (C2) region that it shares with other syndecans. A cell-penetrating peptide containing this sequence competes for HER2-dependent epithelial migration and carcinoma survival, although it is without effect on the EGFR-stimulated mechanism. ß4 mutants bearing mutations specific for Sdc1 and Sdc4 recognition act as dominant negative mutants to block cell spreading or cell migration that depends on HER2 or EGFR, respectively. The interaction of the α6ß4 integrin with the syndecans appears critical for it to be utilized as a signaling platform; migration depends on α3ß1 integrin binding to laminin 332 (LN332; also known as laminin 5), whereas antibodies that block α6ß4 binding are without effect. These findings indicate that specific syndecan family members are likely to have key roles in α6ß4 integrin activation by receptor tyrosine kinases.

Integrated Acetabular Prosthesis Versus Bone Grafting in Total Hip Arthroplasty for Crowe Type II and III Hip Dysplasia: A Retrospective Case-Control Study.

OBJECTIVE: Many methods of acetabular reconstruction with total hip arthroplasty (THA) for Crowe type II and III adult developmental dysplasia of the hip (DDH) acetabular bone defect have been implemented clinically. However, there was no study comparing the results of integrated acetabular prosthesis (IAP) with bone grafting (BG). This study aims to investigate the efficacy of IAP and BG for acetabular reconstruction in Crowe type II and III DDH. METHODS: The clinical data of 45 patients with unilateral Crowe type II and III DDH who underwent THA from January 2020 to January 2023 were retrospectively analyzed. The patients were divided into two groups: 25 patients using 3D-printed IAP (IAP group) and 20 patients using BG (BG group). The operation time and intraoperative blood loss were recorded. The clinical outcomes were assessed by Harris Hip Score (HHS) and full weight-bearing time. The radiological outcomes were evaluated by the radiological examination. Accordingly, intraoperative and postoperative complications were observed as well. The data between the two groups were compared by independent sample t-tests and the Mann-Whitney U rank sum test. RESULTS: There were no significant differences between the two groups in Harris Hip Score (HHS) (preoperative, 6 months postoperative, and the last follow-up), leg length discrepancy (LLD), cup inclination, cup anteversion, vertical center of rotation (V-COR), horizontal center of rotation (H-COR) (p > 0.05). The mean HHS in the IAP group was higher than in the BG group at 1 and 3 months postoperative (p < 0.001). The mean surgical time and blood loss in the IAP group were less than in the BG group (p < 0.001). The mean full weight-bearing time in the IAP group was shorter than in the BG group (p < 0.01). No complications were observed in either group during the follow-up period. CONCLUSION: IAP and BG have similar radiographic outcomes and long-term clinical efficacy in THA for Crowe type II and III DDH, but the IAP technique has higher surgical safety and facilitates the recovery of hip joint function, which is worthy of clinical promotion.

Selective Laser Melting of the Porous Ta Scaffold with Mg-Doped Calcium Phosphate Coating for Orthopedic Applications.

Addressing the repair of large-scale bone defects has become a hot research topic within the field of orthopedics. This study assessed the feasibility and effectiveness of using porous tantalum scaffolds to treat such defects. These scaffolds, manufactured using the selective laser melting (SLM) technology, possessed biomechanical properties compatible with natural bone tissue. To enhance the osteogenesis bioactivity of these porous Ta scaffolds, we applied calcium phosphate (CaP) and magnesium-doped calcium phosphate (Mg-CaP) coatings to the surface of SLM Ta scaffolds through a hydrothermal method. These degradable coatings released calcium and magnesium ions, demonstrating osteogenic bioactivity. Experimental results indicated that the Mg-CaP group exhibited biocompatibility comparable to that of the Ta group in vivo and in vitro. In terms of osteogenesis, both the CaP group and the Mg-CaP group showed improved outcomes compared to the control group, with the Mg-CaP group demonstrating superior performance. Therefore, both CaP and magnesium-CaP coatings can significantly enhance the osseointegration of three-dimensional-printed porous Ta, thereby increasing the surface bioactivity. Overall, the present study introduces an innovative approach for the biofunctionalization of SLM porous Ta, aiming to enhance its suitability as a bone implant material.

Design, fabrication and clinical characterization of additively manufactured tantalum hip joint prosthesis.

The joint prosthesis plays a vital role in the outcome of total hip arthroplasty. The key factors that determine the performance of joint prostheses are the materials used and the structural design of the prosthesis. This study aimed to fabricate a porous tantalum (Ta) hip prosthesis using selective laser melting (SLM) technology. The feasibility of SLM Ta use in hip prosthesis was verified by studying its chemical composition, metallographic structure and mechanical properties. In vitro experiments proved that SLM Ta exhibited better biological activities in promoting osteogenesis and inhibiting inflammation than SLM Ti6Al4V. Then, the topological optimization design of the femoral stem of the SLM Ta hip prosthesis was carried out by finite element simulation, and the fatigue performance of the optimized prosthesis was tested to verify the biomechanical safety of the prosthesis. A porous Ta acetabulum cup was also designed and fabricated using SLM. Its mechanical properties were then studied. Finally, clinical trials were conducted to verify the clinical efficacy of the SLM Ta hip prosthesis. The porous structure could reduce the weight of the prosthesis and stress shielding and avoid bone resorption around the prosthesis. In addition, anti-infection drugs can also be loaded into the pores for infection treatment. The acetabular cup can be custom-designed based on the severity of bone loss on the acetabular side, and the integrated acetabular cup can repair the acetabular bone defect while achieving the function of the acetabular cup.

Research progress and clinical translation of three-dimensional printed porous tantalum in orthopaedics.

With continuous developments in additive manufacturing technology, tantalum (Ta) metal has been manufactured into orthopaedic implants with a variety of forms, properties and uses by three-dimensional printing. Based on extensive research in recent years, the design, processing and performance aspects of this new orthopaedic implant material have been greatly improved. Besides the bionic porous structure and mechanical characteristics that are similar to human bone tissue, porous tantalum is considered to be a viable bone repair material due to its outstanding corrosion resistance, biocompatibility, bone integration and bone conductivity. Numerous in vitro, in vivo, and clinical studies have been carried out in order to analyse the safety and efficacy of these implants in orthopaedic applications. This study reviews the most recent advances in manufacturing, characteristics and clinical application of porous tantalum materials.

Related Risk Factors and Treatment Management of Psoriatic Arthritis Complicated With Cardiovascular Disease.

Psoriatic arthritis (PsA) is a chronic autoimmune inflammatory joint disease related to psoriasis (PsO). The risk of PsA patients with cardiovascular disease (CVD) is significantly higher than that of the general population. At present, the relevant mechanism is not clear, chronic inflammation and traditional cardiovascular risk factors are the most important factors for the increased risk of CVD in PsA patients. Early assessment of the risk of PsA patients with CVD, and active control of the disease activity of PsA patients and intervention of traditional cardiovascular risk factors can delay the progression of CVD risk. This article reviews the epidemiology and pathogenesis between PsA and CVD, and reviews the latest developments in the risk assessment and management of CVD in PsA patients.

An air quality index prediction model based on CNN-ILSTM.

Air quality index (AQI) is an essential measure of air pollution evaluation, which describes the air pollution degree and its impact on health, so the accurate prediction of AQI is significant. This paper presents an AQI prediction model based on Convolution Neural Networks (CNN) and Improved Long Short-Term Memory (ILSTM), named CNN-ILSTM. ILSTM deletes the output gate in LSTM and improves its input gate and forget gate, and introduces a Conversion Information Module (CIM) to prevent supersaturation in the learning process. ILSTM realizes efficient learning of historical data, improves prediction accuracy, and reduces the training time. CNN extracts the eigenvalues of input data effectively. This paper uses air quality data from 00:00 on January 1, 2017, to 23:00 on June 30, 2021, in Shijiazhuang City, Hebei Province, China, as experimental data sets, and compares this model with eight prediction models: SVR, RFR, MLP, LSTM, GRU, ILSTM, CNN-LSTM, and CNN-GRU to prove the validity and accuracy of CNN-ILSTM prediction model. The experimental results show the MAE of CNN-ILSTM is 8.4134, MSE is 202.1923, R2 is 0.9601, and the training time is 85.3 s. In this experiment, the performance of this model performs better than other models.

Interaction of syndecan and alpha6beta4 integrin cytoplasmic domains: regulation of ErbB2-mediated integrin activation.

The alpha6beta4 integrin is a laminin 332 (LN332) receptor central to the formation of hemidesmosomes in epithelial layers. However, the integrin becomes phosphorylated by keratinocytes responding to epidermal growth factor in skin wounds or by squamous cell carcinomas that overexpress/hyperactivate the tyrosine kinase ErbB2, epidermal growth factor receptor, or c-Met. We show here that the beta4-dependent signaling in A431 human squamous carcinoma cells is dependent on the syndecan family of matrix receptors. Yeast two-hybrid analysis identifies an interaction within the distal third (amino acids 1473-1752) of the beta4 cytoplasmic domain and the conserved C2 region of the syndecan cytoplasmic domain. Via its C2 region, Sdc1 forms a complex with the alpha6beta4 integrin along with the receptor tyrosine kinase ErbB2 and the cytoplasmic kinase Fyn in A431 cells. Engagement of LN332 or clustering of the alpha6beta4 integrin with integrin-specific antibodies causes phosphorylation of ErbB2, Fyn, and the beta4 subunit as well as activation of phosphatidylinositol 3-kinase and Akt and their assimilation into this complex. This leads to phosphatidylinositol 3-kinase-dependent cell spreading and Akt-dependent protection from apoptosis. This is disrupted by RNA interference silencing of Sdc1 but can be rescued by mouse Sdc1 or Sdc4 but not by syndecan mutants lacking their C-terminal C2 region. This disruption does not prevent the phosphorylation of ErbB2 or Fyn but blocks the Fyn-mediated phosphorylation of the beta4 tail. We propose that syndecans engage the distal region of the beta4 cytoplasmic domain and bring it to the plasma membrane, where it can be acted upon by Src family kinases.

Effects of acetylsalicylic acid on increase of fibrin network porosity and the consequent upregulation of fibrinolysis.

Our earlier study in vivo showed that a lower dose of acetylsalicylic acid (ASA) brought greater enhancement in fibrin gel permeability (Ks) than a higher dose. To assess whether this finding related to modifications of fibrinogen clotting property by ASA, purified fibrinogen was incubated with ASA and/or salicylic acid (SA). The fibrinogen product was examined. Fibrinogen "clotting time" was not affected. Shortening of fibrin clot "lysis time" paralleled the increase of fibrin network porosity demonstrated by measurements of liquid permeability (Ks), fibrin fiber thickness, and 3-dimensional microscopic image, in a low ASA concentration-dependent way. Ks levels were not altered by SA alone but significantly decreased in samples treated by both where the concentrations were low for ASA and high for SA. In conclusion, ASA at the concentrations used did not influence the rate of fibrinogen gelation by thrombin. However, assembly of fibrin monomers was most probably altered, leading to enhancement of fibrin fiber thickness. A looser network was constructed by the thicker fibrin fibers, which benefits fibrinolysis. According to the known mechanism that SA interferes with ASA in preventing acetylation of platelet's proteins, an explanation for the low ASA concentration-dependent effects on fibrin network structure may be that fewer molecules of SA-the hydrolytic product of ASA-are generated from lower doses of ASA, which block acetylation of fibrinogen to a smaller extent and thus more significantly impair fibrin formation.

The interaction between plasminogen and antiplasmin variants as studied by surface plasmon resonance.

The interaction between immobilized plasminogen or an elastase-degradation product from plasminogen, constituting "kringles" 1-3 and different purified variants of antiplasmin has been studied by surface plasmon resonance utilising a BIAcore. The antiplasmin variants studied are wild-type, K429E, K436E, E443G, D444G, K452E and K452T. It is shown that the two mutants K452T and K452E react in quite a similar way as wt-antiplasmin, suggesting that Lys452 is not involved in the lysine-binding site interaction between plasminogen and antiplasmin. On the other hand, the mutant K436E displays a much lower k(a). The affinity between plasminogen or the fragment constituting "kringles" 1-3 and K436E were also much lower than with wt-antiplasmin. Thus, also the data obtained with surface plasmon resonance show that Lys436 indeed is very important in the lysine-binding site mediated interaction between plasminogen and antiplasmin.

Structures of importance for the stability of antiplasmin as studied by site-directed mutagenesis.

Human antiplasmin, a fast-acting inhibitor of plasmin in plasma, belongs to the serpin super-family of proteins. Like other members of this family, antiplasmin has a scissile peptide bond exposed within a reactive centre loop, typically present at the surface of the molecule. Antiplasmin is stable at neutral pH, but at acidic pH or at elevated temperatures it rapidly becomes inactivated. Data regarding "native" antiplasmin have demonstrated that both polymerization processes and formation of latent molecules are important in this respect. In this work we used site-directed mutagenesis to produce 11 single-site mutants (mainly within Abeta-sheet, Bbeta-sheet and reactive centre loop), which were expressed in Drosophila S2 cells, purified and characterized. Five of the 11 mutants were found to have a deviating stability at decreased pH. Glu346Thr was the only mutant with a lesser stability as compared to wt-antiplasmin, but the other 4 were more stable. The most stable mutant, His341Thr, was 7-fold more stable at pH 4.9 as compared to wt-antiplasmin. The wt-antiplasmin had a much more pronounced tendency to polymerize at decreased pH, as compared to "native" antiplasmin. However, many of the mutants clearly rather formed latent molecules, as judged both from PAGE-analysis at non-denaturing condition and reactivation experiments.

Inactivation of antiplasmin at low pH: evidence for the formation of latent molecules.

Several serine proteinase inhibitors (serpins) are metastable proteins which under certain conditions may undergo conformational changes resulting in the insertion of the reactive centre loop into the so-called Abeta-sheet and hence forming latent molecules. Here we have studied the inactivation of antiplasmin as a function of pH and temperature with time. At decreased pH (4.9-5.8) and at room temperature, antiplasmin activity decreased following first-order kinetics. Analysis by polyacrylamide gel electrophoresis under non-denaturing conditions demonstrated that only minor amounts of polymerized material formed after extensive incubation (4 days) at room temperature. However, on incubation at elevated temperatures (45 or 55 degrees C), a rapid formation of polymerized material was observed. We also demonstrated that antiplasmin inactivated by treatment at pH approximately 5 at room temperature spontaneously slowly regained some activity if incubated in a buffer of neutral pH. Furthermore, by treatment with 4 M guanidinium chloride for about 30 min, followed by dialysis against a neutral phosphate buffer, considerable activity (almost 40%) was regained. Thus, we conclude that antiplasmin, at least partially, at lower temperatures is transformed into a latent form, which could be reactivated, in a similar manner as PAI-1. At increased temperature, however, polymerization seems to be the predominant reason for inactivation.

Identification of amino acids in antiplasmin involved in its noncovalent 'lysine-binding-site'-dependent interaction with plasmin.

The lysine-binding-site-mediated interaction between plasmin and antiplasmin is of great importance for the fast rate of this reaction. It also plays an important part in regulating the fibrinolytic enzyme system. To identify structures important for its noncovalent interaction with plasmin, we constructed seven single-site mutants of antiplasmin by modifying charged amino acids in the C-terminal part of the molecule. All the variants were expressed in the Drosophila S2 cell system, purified, and shown to form stable complexes with plasmin. A kinetic evaluation revealed that two mutants of the C-terminal lysine (K452E or K452T) did not differ significantly from wild-type antiplasmin in their reactions with plasmin, in either the presence or absence of 6-aminohexanoic acid, suggesting that this C-terminal lysine is not important for this reaction. On the other hand, modification of Lys436 to Glu decreased the reaction rate about fivefold compared with wild-type. In addition, in the presence of 6-aminohexanoic acid, only a small decrease in the reaction rate was observed, suggesting that Lys436 is important for the lysine-binding-site-mediated interaction between plasmin and antiplasmin. Results from computerized molecular modelling of the C-terminal 40 amino acids support our experimental data.