COMP promotes pancreatic fibrosis by activating pancreatic stellate cells through CD36-ERK/AKT signaling pathways.

BACKGROUND: Pancreatic fibrosis is one of the most important pathological features of chronic pancreatitis (CP) and pancreatic stellate cells (PSCs) are the key cells of fibrosis. As an extracellular matrix (ECM) glycoprotein, cartilage oligomeric matrix protein (COMP) is critical for collagen assembly and ECM stability and recent studies showed that COMP exert promoting fibrosis effect in the skin, lungs and liver. However, the role of COMP in activation of PSCs and pancreatic fibrosis remain unclear. We aimed to investigate the role and specific mechanisms of COMP in regulating the profibrotic phenotype of PSCs and pancreatic fibrosis. METHODS: ELISA method was used to determine serum COMP in patients with CP. Mice model of CP was established by repeated intraperitoneal injection of cerulein and pancreatic fibrosis was evaluated by Hematoxylin-Eosin staining (H&E) and Sirius red staining. Immunohistochemical staining was used to detect the expression changes of COMP and fibrosis marker such as α-SMA and Fibronectin in pancreatic tissue of mice. Cell Counting Kit-8, Wound Healing and Transwell assessed the proliferation and migration of human pancreatic stellate cells (HPSCs). Western blotting, qRT-PCR and immunofluorescence staining were performed to detect the expression of fibrosis marker, AKT and MAPK family proteins in HPSCs. RNA-seq omics analysis as well as small interfering RNA of COMP, recombinant human COMP (rCOMP), MEK inhibitors and PI3K inhibitors were used to study the effect and mechanism of COMP on activation of HPSCs. RESULTS: ELISA showed that the expression of COMP significantly increased in the serum of CP patients. H&E and Sirius red staining analysis showed that there was a large amount of collagen deposition in the mice in the CP model group and high expression of COMP, α-SMA, Fibronectin and Vimentin were observed in fibrotic tissues. TGF-ß1 stimulates the activation of HPSCs and increases the expression of COMP. Knockdown of COMP inhibited proliferation and migration of HPSCs. Further, RNA-seq omics analysis and validation experiments in vitro showed that rCOMP could significantly promote the proliferation and activation of HPSCs, which may be due to promoting the phosphorylation of ERK and AKT through membrane protein receptor CD36. rCOMP simultaneously increased the expression of α-SMA, Fibronectin and Collagen I in HPSCs. CONCLUSION: In conclusion, this study showed that COMP was up-regulated in CP fibrotic tissues and COMP induced the activation, proliferation and migration of PSCs through the CD36-ERK/AKT signaling pathway. COMP may be a potential therapeutic candidate for the treatment of CP. Interfering with the expression of COMP or the communication between COMP and CD36 on PSCs may be the next direction for therapeutic research.

The molecular mechanism of thrombospondin family members in cardiovascular diseases.

Cardiovascular diseases have been identified as vital factors in global morbidity and mortality in recent years. The available evidence suggests that various cytokines and pathological proteins participate in these complicated and changeable diseases. The thrombospondin (TSP) family is a series of conserved, multidomain calcium-binding glycoproteins that cause cell-matrix and cell-cell effects via interactions with other extracellular matrix components and cell surface receptors. The TSP family has five members that can be divided into two groups (Group A and Group B) based on their different structures. TSP-1, TSP-2, and TSP-4 are the most studied proteins. Among recent studies and findings, we investigated the functions of several family members, especially TSP-5. We review the basic concepts of TSPs and summarize the relevant molecular mechanisms and cell interactions in the cardiovascular system. Targeting TSPs in CVD and other diseases has a remarkable therapeutic benefit.

Diagnostic value of serum COMP and ADAMTS7 for intervertebral disc degeneration.

OBJECTIVE: Intervertebral disc degeneration (IVDD) is a major cause of morbidity and disability. Our study aimed to investigate the potential of cartilage oligomeric matrix protein (COMP) and ADAMTS7 (A disintegrin and metalloproteinases with thrombospondin motifs 7) as biomarkers for IVDD together with their functional relationship. METHODS: IVD tissues and peripheral blood samples were collected from IVDD rabbit models over 1-4 weeks. Tissues and blood samples were also collected from clinical patients those were stratified into four equal groups according to Pfirrmann IVDD grading (I-V) with baseline data collected for each participant. COMP and ADAMTS7 expression were analyzed and biomarker characteristics were assessed using linear regression and receiver operating curve (ROC) analyses. RESULTS: COMP and ADAMTS7 expression increased in tissues and serum during IVDD progression. Serum COMP (sCOMP) and serum ADAMTS7 (sADAMTS7) levels increased in a time-dependent manner following IVD damage in the rabbit model while significant positive correlations were detected between sCOMP and sADAMTS7 and Pfirrmann grade in human subjects. ROC analysis showed that combining sCOMP and sADAMTS7 assay results produced an improved diagnostic measure for IVDD compared to individual sCOMP or sADAMTS7 tests. In vitro assays conducted on human cell isolates revealed that COMP prevented extracellular matrix degradation and antagonized ADAMTS7 expression although this protective role was uncoupled under microenvironmental conditions mimicking IVDD. CONCLUSIONS: Increases in circulating COMP and ADAMTS7 correlate with IVDD progression and may play regulatory roles. Assays for sCOMP and/or sADAMTS7 levels can discriminate between healthy subjects and IVDD patients, warranting further clinical assessment.

Modifying loading during gait leads to biochemical changes in serum cartilage oligomeric matrix protein concentrations in a subgroup of individuals with anterior cruciate ligament reconstruction.

PURPOSE: Strong observational evidence has linked changes in limb loading during walking following anterior cruciate ligament reconstruction (ACLR) to posttraumatic osteoarthritis (PTOA). It remains unknown if manipulating peak loading influences joint tissue biochemistry. Thus, the purpose of this study is to determine whether manipulating peak vertical ground reaction force (vGRF) during gait influences changes in serum cartilage oligomeric matrix protein (sCOMP) concentrations in ACLR participants. METHODS: Forty ACLR individuals participated in this randomized crossover study (48% female, age = 21.0 ± 4.4 years, BMI = 24.6 ± 3.1). Participants attended four sessions, wherein they completed one of four biofeedback conditions (habitual loading (no biofeedback), high loading (5% increase in vGRF), low loading (5% decrease in vGRF), and symmetrical loading (between-limb symmetry in vGRF)) while walking on a treadmill for 3000 steps. Serum was collected before (baseline), immediately (acute post), 1 h (1 h post), and 3.5 h (3.5 h post) following each condition. A comprehensive general linear mixed model was constructed to address the differences in sCOMP across all conditions and timepoints in all participants and a subgroup of sCOMP Increasers. RESULTS: No sCOMP differences were found across the entire cohort. In the sCOMP Increasers, a significant time × condition interaction was found (F9,206 = 2.6, p = 0.009). sCOMP was lower during high loading than low loading (p = 0.009) acutely (acute post). At 3.5 h post, sCOMP was higher during habitual loading than symmetrical loading (p = 0.001). CONCLUSION: These data suggest that manipulating lower limb loading in ACLR patients who habitually exhibit an acute increase in sCOMP following walking results in improved biochemical changes linked to cartilage health. Key Points • This study assesses the mechanistic link between lower limb load modification and joint tissue biochemistry at acute and delayed timepoints. • Real-time biofeedback provides a paradigm to experimentally assess the mechanistic link between loading and serum biomarkers. • Manipulating peak loading during gait resulted in a metabolic effect of lower sCOMP concentrations in a subgroup of ACLR individuals. • Peak loading modifications may provide an intervention strategy to mitigate the development of PTOA following ACLR.

Shiga toxin type 2 B subunit protects mice against toxin challenge when leashed and bundled by a stable pentameric coiled-coil molecule.

Vaccines against Shiga toxin (Stx)-producing Escherichia coli (STEC) have not yet been developed. Two immunologically distinct serotypes of Stx (Stx1 and Stx2) are the main virulence factors of STEC. Thus, blocking their B subunits (StxB) from binding to the cell surface receptor globotriaosylceramide (Gb3) efficiently prevents the action of these toxins. We expressed Stx1B and Stx2B in E. coli inclusion bodies and reassembled them into pentamers by a stepwise dialysis. Stx1B pentamer fully protected mice against Stx1 challenge, but Stx2B pentamer failed to protect mice against Stx2 challenge. To explain those observations, we proposed that the pentamer of Stx2B readily dissociates into its constituent monomers, especially under in vivo conditions, thus being unable to induce pentamer-specific immunity. To increase pentamer stability, we fused the B subunit to a pentameric coiled-coil domain of the cartilage oligomeric matrix protein (COMP). This "five-to-five" fusion hybrid molecule (Stx2B-COMP) was shown to be protective against Stx2 challenge, demonstrating that the Stx2B subunit when leashed and bundled by a rigid pentameric coiled-coil domain mount a pentamer-specific immune response and efficiently neutralize the toxin both in vitro and in vivo. Our data strongly suggest that the Stx2B subunit moiety fluctuates between a pentameric and monomeric state within the fusion protein, which may increase the likelihood of the immune system recognizing the pentameric conformation for toxin neutralization.

Early Resveratrol Treatment Mitigates Joint Degeneration and Dampens Pain in a Mouse Model of Pseudoachondroplasia (PSACH).

Pseudoachondroplasia (PSACH), a severe dwarfing condition associated with early-onset joint degeneration and lifelong joint pain, is caused by mutations in cartilage oligomeric matrix protein (COMP). The mechanisms underlying the mutant-COMP pathology have been defined using the MT-COMP mouse model of PSACH that has the common D469del mutation. Mutant-COMP protein does not fold properly, and it is retained in the rough endoplasmic reticulum (rER) of chondrocytes rather than being exported to the extracellular matrix (ECM), driving ER stress that stimulates oxidative stress and inflammation, driving a self-perpetuating cycle. CHOP (ER stress signaling protein) and TNFα inflammation drive high levels of mTORC1 signaling, shutting down autophagy and blocking ER clearance, resulting in premature loss of chondrocytes that negatively impacts linear growth and causes early joint degeneration in MT-COMP mice and PSACH. Previously, we have shown that resveratrol treatment from birth to 20 weeks prevents joint degeneration and decreases the pathological processes in articular chondrocytes. Resveratrol's therapeutic mechanism of action in the mutant-COMP pathology was shown to act by primarily stimulating autophagy and reducing inflammation. Importantly, we demonstrated that MT-COMP mice experience pain consistent with PSACH joint pain. Here, we show, in the MT-COMP mouse, that resveratrol treatment must begin within 4 weeks to preserve joint health and reduce pain. Resveratrol treatment started at 6 or 8 weeks (to 20 weeks) was not effective in preventing joint degeneration. Collectively, our findings in MT-COMP mice show that there is a postnatal resveratrol treatment window wherein the inevitable mutant-COMP joint degeneration and pain can be prevented.

Functional characterization of a rare pathogenic variant c.875G > A, p.(Cys292Tyr) in COMP.

BACKGROUND: The protein encoded by the cartilage oligomeric matrix protein (COMP) gene is a noncollagenous extracellular matrix (ECM) protein that is important for chondrocyte formation and growth. Variations in the COMP gene cause pseudoachondroplasia (PSACH), which is mainly characterized by short-limbed dwarfing in the clinic. AIMS: To characterize the function of a rare pathogenic variant in the COMP gene (c.875G > A, p.Cys292Tyr). MATERIALS & METHODS: We performed 3D structural analysis, in vitro expression analysis, and immunofluorescence to characterize the effects of the variant on protein structure, expression, and cellular localization respectively. RESULTS: Variation modeling showed that the interactions between amino acids were changed after the variation, and there were 31 changes in the secondary structure of mutant COMP (MT-COMP). Western blot showed that the intracellular quantity of MT-COMP was higher than the wild-type COMP (WT-COMP). Cellular immunofluorescence results showed that WT-COMP was less abundant and homogenously distributed in cells, while the MT-COMP accumulated in the cytoplasm. DISCUSSION: Herein, we report a variant of COMP in a Chinese family with PSACH. We have shown that the rare missense variant, COMP c.875G > A, previously reported in ClinVar and identified in our patient, results in excessive accumulation of mutant protein in the cytoplasm, and is therefore pathogenic. CONCLUSION: Through in silico and experimental analyses, we provide evidence that COMP c.875G > A is the likely cause of PSACH in a Chinese family.

Expression of Cartilage Oligomeric Matrix Protein in colorectal cancer is an adverse prognostic factor and correlates negatively with infiltrating immune cells and PD-L1 expression.

Introduction: Cartilage Oligomeric Matrix Protein (COMP) is an oncogenic protein that has been associated with a decrease in infiltrating T-cells in periampullary adenocarcinoma. This study aimed to investigate whether this is also the case for colorectal cancer (CRC) and to evaluate the relationship between COMP expression and clinopathological features. Methods: Immunohistochemistry was used to determine the expression levels of COMP in tumor cells and stroma in primary tumors from a cohort of 537 CRC patients. The expression of immune cell markers, including CD3+, CD8+, FoxP3+, CD68+, CD56+, CD163+, and PD-L1, was evaluated previously. Tumor fibrosis was assessed by Sirius Red staining and evaluation of collagen fiber organization. Results: COMP expression correlated positively with TNM-stage and grade of differentiation. Patients with CRC expressing high levels of COMP had significantly shorter OS than those with low COMP expression (p<0.0001), and fewer infiltrating T-cells were detected in tumors with high COMP expression. Additionally, a negative correlation was identified between the expression of COMP and PD-L1 on both tumor cells and immune cells. Cox regression analysis showed that tumors expressing high levels of COMP had significantly shorter OS, independent of all evaluated immune cell markers. Tumor fibrosis was correlated with high expression of COMP in the stroma (p<0.0001), and tumors with high levels of COMP expression and denser fibrosis displayed more sparse immune cell infiltration. Discussion: The results suggest that COMP expression in CRC may exert an immune regulatory effect by increasing dense fibrosis and decreasing immune cell infiltration. These findings support the notion that COMP is an important factor in the development and progression of CRC.

TGFBI as a candidate biomarker for non-invasive diagnosis of early-stage endometriosis.

STUDY QUESTION: Can cartilage oligomeric matrix protein (COMP) and transforming growth factor-ß-induced protein ig-h3 (TGFBI) alone or in combination with cancer antigen 125 (CA-125) be considered as potential blood biomarkers of endometriosis? SUMMARY ANSWER: The results of this study indicate that COMP has no diagnostic value. TGFBI has potential as a non-invasive biomarker of the early stages of endometriosis, while TGFBI together with CA-125 has similar diagnostic characteristics as CA-125 alone for all stages of endometriosis. WHAT IS KNOWN ALREADY: Endometriosis is a common, chronic gynecological disease that significantly affects patient quality of life by causing pain and infertility. The gold standard for diagnosis is visual inspection of pelvic organs by laparoscopy, therefore there is an urgent need for discovery of non-invasive biomarkers for endometriosis to reduce diagnostic delays and allow earlier treatment of patients. The potential biomarkers for endometriosis evaluated in this study (COMP and TGFBI) were previously identified by our proteomic analysis of peritoneal fluid samples. STUDY DESIGN, SIZE, DURATION: This is a case-control study divided into a discovery (n = 56 patients) and a validation phase (n = 237 patients). All patients were treated between 2008 and 2019 in a tertiary medical center. PARTICIPANTS/MATERIALS, SETTING, METHOD: Patients were stratified based on the laparoscopic findings. The discovery phase included 32 endometriosis patients (cases) and 24 patients with confirmed absence of endometriosis (controls). The validation phase included 166 endometriosis and 71 control patients. Concentrations of COMP and TGFBI were measured by ELISA in plasma samples, whereas concentration of CA-125 was measured using a clinically validated assay for serum samples. Statistical and receiver operating characteristic (ROC) curve analyses were performed. The classification models were built using the linear support vector machine (SVM) method with the SVM built-in feature ranking method. MAIN RESULTS AND THE ROLE OF CHANCE: The discovery phase revealed significantly increased concentration of TGFBI, but not COMP, in plasma samples of patients with endometriosis compared to controls. In this smaller cohort, univariate ROC analysis showed fair diagnostic potential of TGFBI, with an AUC value of 0.77, sensitivity of 58%, and specificity of 84%. The classification model built using linear SVM and combining TGFBI and CA-125 showed an AUC value of 0.91, sensitivity of 88% and specificity of 75% in distinguishing patients with endometriosis from controls. The validation phase results revealed similar diagnostic characteristics of the SVM model combining TGFBI and CA-125, with an AUC value of 0.83, sensitivity of 83% and specificity of 67% and CA-125 alone with AUC value of 0.83, sensitivity of 73% and specificity of 80%. TGFBI exhibited good diagnostic potential for early-stage endometriosis (revised American Society for Reproductive Medicine stage I-II), with an AUC value of 0.74, sensitivity of 61% and specificity of 83% compared to CA-125, which had an AUC value of 0.63, sensitivity of 60% and specificity of 67%. An SVM model combining TGFBI and CA-125 showed a high AUC value of 0.94 and sensitivity of 95% for diagnosing moderate-to-severe endometriosis. LIMITATIONS, REASONS FOR CAUTION: The diagnostic models were built and validated from a single endometriosis center, and thus further validation and technical verification in a multicenter study with a larger cohort is needed. Additional limitation was lack of histological confirmation of disease for some patients in the validation phase. WIDER IMPLICATIONS OF THE FINDINGS: This study revealed for the first time increased concentration of TGFBI in plasma samples of patients with endometriosis, particularly those with minimal-to-mild endometriosis, compared to controls. This is the first step in considering TGFBI as a potential non-invasive biomarker for the early stages of endometriosis. It also opens a path for new basic research to investigate the importance of TGFBI in the pathophysiology of endometriosis. Further studies are needed to confirm the diagnostic potential of a model based on TGFBI and CA-125 for the non-invasive diagnosis of endometriosis. STUDY FUNDING/COMPETING INTEREST(S): The preparation of this manuscript was supported by grant J3-1755 from the Slovenian Research Agency to T.L.R and EU H2020-MSCA-RISE project TRENDO (grant 101008193). All authors declare that they have no conflicts of interest. TRIAL REGISTRATION NUMBER: NCT0459154.

Induction of antitoxic antibody and preventive effect against porcine edema disease by the pentameric Stx2eB subunit vaccine.

Porcine edema disease (ED) is an enterotoxaemia that frequently occurs in 4-12 week-old piglets and results in high mortality. ED is caused by Shiga toxin 2e (Stx2e), produced by host-adapted Shiga toxin-producing Escherichia coli (STEC) strains. We constructed a recombinant protein in which the B subunit of Stx2e (Stx2eB) was linked to Cartilage Oligomeric Matrix Protein (COMP)'s pentameric domain to enhance antigenicity to induce neutralizing antibodies against Stx2e. We evaluated the efficacy of this antigen as a vaccine on the farm where ED had occurred. The suckling piglets were divided into two groups. The pigs in the vaccinated group were intramuscularly immunized with the vaccine containing 30 µg/head of Stx2eB-COMP at 1 and 4 weeks of age. The control pigs were injected with saline instead of the vaccine. The neutralizing antibody titer to Stx2e, mortality, clinical score, and body weight was evaluated up to 11 weeks after the first vaccination. In the vaccinated group, the Stx2e neutralizing antibody was detected 3 weeks after the first vaccination, its titer increased during the following weeks. The antibody was not detected in the control group during the test period. The STEC gene was detected in both groups during the test period, but a typical ED was observed only in control pigs; the mortality and clinical score were significantly lower in the vaccinated group than in the control group. These data indicate that the pentameric B subunit vaccine is effective for preventing ED and offers a promising tool for pig health control.

Co-occurrence of neurofibromatosis type 1 and pseudoachondroplasia - a first case report.

BACKGROUND: Neurofibromatosis type 1 and pseudoachondroplasia are both rare autosomal dominant disorders, caused by pathogenic mutations in NF1 and COMP genes, respectively. Both neurofibromin 1 and cartilage oligomeric matrix protein (COMP) play a role in the development of the skeleton. Carrying both germline mutations has not been previously reported; however, it can affect the developing phenotype. CASE PRESENTATION: The index patient, an 8-year-old female presented with several skeletal and dermatologic anomalies resembling the coexistence of multiple syndromes. Her mother had dermatologic symptoms characteristic for neurofibromatosis type 1, and her father presented with distinct skeletal anomalies. NGS-based analysis revealed a heterozygous pathogenic mutation in genes NF1 and COMP in the index patient. A previously unreported heterozygous variant was detected for the NF1 gene. The sequencing of the COMP gene revealed a previously reported, pathogenic heterozygous variant that is responsible for the development of the pseudoachondroplasia phenotype. CONCLUSIONS: Here, we present the case of a young female carrying pathogenic NF1 and COMP mutations, diagnosed with two distinct heritable disorders, neurofibromatosis type 1 and pseudoachondroplasia. The coincidence of two monogenic autosomal dominant disorders is rare and can pose a differential diagnostic challenge. To the best of our knowledge, this is the first reported co-occurrence of these syndromes.

Chondroitin Sulfate-Tyramine-Based Hydrogels for Cartilage Tissue Repair.

The degradation of cartilage, due to trauma, mechanical load or diseases, results in abundant loss of extracellular matrix (ECM) integrity and development of osteoarthritis (OA). Chondroitin sulfate (CS) is a member of the highly sulfated glycosaminoglycans (GAGs) and a primary component of cartilage tissue ECM. In this study, we aimed to investigate the effect of mechanical load on the chondrogenic differentiation of bone marrow mesenchymal stem cells (BM-MCSs) encapsulated into CS-tyramine-gelatin (CS-Tyr/Gel) hydrogel in order to evaluate the suitability of this composite for OA cartilage regeneration studies in vitro. The CS-Tyr/Gel/BM-MSCs composite showed excellent biointegration on cartilage explants. The applied mild mechanical load stimulated the chondrogenic differentiation of BM-MSCs in CS-Tyr/Gel hydrogel (immunohistochemical collagen II staining). However, the stronger mechanical load had a negative effect on the human OA cartilage explants evaluated by the higher release of ECM components, such as the cartilage oligomeric matrix protein (COMP) and GAGs, compared to the not-compressed explants. Finally, the application of the CS-Tyr/Gel/BM-MSCs composite on the top of the OA cartilage explants decreased the release of COMP and GAGs from the cartilage explants. Data suggest that the CS-Tyr/Gel/BM-MSCs composite can protect the OA cartilage explants from the damaging effects of external mechanical stimuli. Therefore, it can be used for investigation of OA cartilage regenerative potential and mechanisms under the mechanical load in vitro with further perspectives of therapeutic application in vivo.

CurQ+, a Next-Generation Formulation of Curcumin, Ameliorates Growth Plate Chondrocyte Stress and Increases Limb Growth in a Mouse Model of Pseudoachondroplasia.

Mutations in cartilage oligomeric matrix protein (COMP) causes protein misfolding and accumulation in chondrocytes that compromises skeletal growth and joint health in pseudoachondroplasia (PSACH), a severe dwarfing condition. Using the MT-COMP mice, a murine model of PSACH, we showed that pathological autophagy blockage was key to the intracellular accumulation of mutant-COMP. Autophagy is blocked by elevated mTORC1 signaling, preventing ER clearance and ensuring chondrocyte death. We demonstrated that resveratrol reduces the growth plate pathology by relieving the autophagy blockage allowing the ER clearance of mutant-COMP, which partially rescues limb length. To expand potential PSACH treatment options, CurQ+, a uniquely absorbable formulation of curcumin, was tested in MT-COMP mice at doses of 82.3 (1X) and 164.6 mg/kg (2X). CurQ+ treatment of MT-COMP mice from 1 to 4 weeks postnatally decreased mutant COMP intracellular retention, inflammation, restoring both autophagy and chondrocyte proliferation. CurQ+ reduction of cellular stress in growth plate chondrocytes dramatically reduced chondrocyte death, normalized femur length at 2X 164.6 mg/kg and recovered 60% of lost limb growth at 1X 82.3 mg/kg. These results indicate that CurQ+ is a potential therapy for COMPopathy-associated lost limb growth, joint degeneration, and other conditions involving persistent inflammation, oxidative stress, and a block of autophagy.

Cartilage oligomeric matrix protein acts as a molecular biomarker in multiple cancer types

Purpose The main function of cartilage oligomeric matrix protein (COMP) is to maintain the synthesis and stability of the extracellular matrix by interacting with collagen. At present, there are relatively few studies on the role of this protein in tumors. This study aimed to explore the relationship between COMP and pan-cancer, and analyzed its diagnostic and prognostic value. Methods The Cancer Genome Atlas database, the Genotype-Tissue Expression database and the Cancer Cell Line Encyclopedia database was used for gene expression analysis. The receiver operating characteristic curve was used to assess the diagnostic value of COMP in pan-cancer. Kaplan–Meier plots were used to assess the relationship between COMP expression and prognosis of cancers (AU)

Immediate Effects of Walking With a Knee Brace After Anterior Cruciate Ligament Reconstruction: A Biomechanical, Biochemical, and Structural Approach.

CONTEXT: Individuals who undergo anterior cruciate ligament reconstruction (ACLR) are at higher risk of posttraumatic osteoarthritis. Altered joint tissue loading caused by aberrant gait biomechanics leads to deleterious changes in joint health linked to the onset of posttraumatic osteoarthritis. Knee braces have been used to modify joint tissue loading in individuals with joint injury, yet the effects of walking with a brace after ACLR on biomechanical, biochemical, and structural cartilage outcomes are unknown. OBJECTIVE: To compare biomechanical, biochemical, and structural outcomes between braced and nonbraced walking in individuals with ACLR. DESIGN: Crossover study. SETTING: Research laboratory. PATIENTS OR OTHER PARTICIPANTS: A total of 34 individuals with unilateral ACLR (18 females, 16 males; time since ACLR = 50.1 ± 36.8 months). INTERVENTION(S): Gait biomechanics were assessed during braced and unbraced conditions on separate days. MAIN OUTCOME MEASURE(S): Vertical ground reaction force, knee-flexion angle, and internal knee-extension moment waveforms were evaluated throughout the stance phase and compared between conditions. Percentage changes in serum cartilage oligomeric matrix protein (%ΔCOMP) and femoral cartilage cross-sectional area (%ΔCSA) measured via ultrasound were calculated after a 3000-step walking protocol. RESULTS: Braced walking increased the knee-flexion angle (largest difference = 3.56°; Cohen d effect size = 1.72) and knee-extension moment (largest difference = -0.48% body weight × height; Cohen d effect size = -1.14) compared with nonbraced walking but did not influence vertical ground reaction force. Whereas no difference (P = .20) in %ΔCOMP existed between the braced and nonbraced conditions in the entire cohort (n = 30 with complete blood data), a larger increase (P = .04) in %ΔCOMP was seen during nonbraced than braced walking in individuals who demonstrated increased COMP during nonbraced walking. No difference (P = .86) in %ΔCSA was present between the braced and nonbraced conditions. CONCLUSIONS: Braced walking may improve sagittal-plane gait biomechanics and %ΔCOMP in a subset of individuals who demonstrate a typical increased COMP response to load (ie, increase in COMP) after nonbraced walking.

Cartilage oligomeric matrix protein acts as a molecular biomarker in multiple cancer types.

PURPOSE: The main function of cartilage oligomeric matrix protein (COMP) is to maintain the synthesis and stability of the extracellular matrix by interacting with collagen. At present, there are relatively few studies on the role of this protein in tumors. This study aimed to explore the relationship between COMP and pan-cancer, and analyzed its diagnostic and prognostic value. METHODS: The Cancer Genome Atlas database, the Genotype-Tissue Expression database and the Cancer Cell Line Encyclopedia database was used for gene expression analysis. The receiver operating characteristic curve was used to assess the diagnostic value of COMP in pan-cancer. Kaplan-Meier plots were used to assess the relationship between COMP expression and prognosis of cancers. R software v4.1.1 was used for statistical analysis, and the ggplot2 package was used for visualization. RESULTS: COMP was significantly overexpressed in 15 human cancers and showed significantly difference in 12 molecular subtypes and 16 immune subtypes. In addition, the expression of COMP is associated with tumor immune evasion. The ROC curve showed that the expression of COMP could predict the occurrence of 16 kinds of tumors with relative accuracy, including adrenocortical carcinoma (ACC) (AUC = 0.737), breast invasive carcinoma (BRCA) (AUC = 0.896), colon adenocarcinoma (COAD) (AUC = 0.760), colon adenocarcinoma/rectum adenocarcinoma esophageal carcinoma (COADREAD) (AUC = 0.775), lymphoid neoplasm diffuse large B-cell lymphoma (DLBC) (AUC = 0.875), kidney renal papillary cell carcinoma (KIRP) (AUC = 0.773), kidney chromophobe (KICH) (AUC = 0.809), ovarian serous cystadenocarcinoma (OV) (AUC = 0.906), prostate adenocarcinoma (PRAD) (AUC = 0.721), pancreatic adenocarcinoma (PAAD) (AUC = 0.944), rectum adenocarcinoma (READ) (AUC = 0.792), skin cutaneous melanoma (SKCM) (AUC = 0.746), stomach adenocarcinoma (STAD) (AUC = 0.711), testicular germ cell tumors (TGCT) (AUC = 0.823), thymoma (THYM) (AUC = 0.777) and uterine carcinosarcoma (UCS) (AUC = 0.769). Furthermore, COMP expression was correlated with overall survival (OS), disease-specific survival (DSS) and progression-free interval (PFI) in ACC (OS, HR = 4.95, DSS, HR = 5.55, PFI, HR = 2.79), BLCA (OS, HR = 1.59, DSS, HR = 1.72, PFI, HR = 1.36), KIRC (OS, HR = 1.36, DSS, HR = 1.94, PFI, HR = 1.57) and COADREAD (OS, HR = 1.46, DSS, HR = 1.98, PFI, HR = 1.43). We selected previously unreported bladder urothelial carcinoma (BLCA) for further study and found that COMP could be an independent risk factor for OS, DSS and PFI. Moreover, we found differentially expressed genes of COMP in BLCA and obtained top 10 hub genes, including LGR4, LGR5, RSPO2, RSPO1, RSPO3, RNF43, ZNRF3, FYN, LYN and SYK. Finally, we verified the function of COMP at the cellular level by using J82 and T24 cells and found that knockdown of COMP could significantly inhibit migration and invasion. This finding supports that COMP could be a potential biomarker for pan-cancer diagnosis and prognosis encompassing tumor microenvironment, disease stage and prognosis. CONCLUSION: This finding supports that COMP could be a potential biomarker for pan-cancer diagnosis and prognosis encompassing tumor microenvironment, disease stage and prognosis.

Study on the relationship between local muscle fatigue and related metabolic biomarkers in simulated manual lifting / 中国职业医学

{L-End}Objective To analyze the local muscle response under continuous ergonomic workload by simulating manual lifting, and to screen the sensitive metabolic biomarkers during fatigue process. {L-End}Methods A total of 13 healthy male volunteers were selected as the study subjects using simple random sampling method. Study subjects underwent repetitive simulated manual lifting for four periods (T1 to T4), each lasting 12 minutes. The degree of work-related fatigue in the forearm, upper arm, shoulder, back, and leg muscles, and the whole body was accessed using Borg 6-20 Rating of Perceived Exertion (RPE) Scale. The venous blood samples were collected from elbow between each two periods to detect the levels of eight metabolic biomarkers: ammonia, lactate, creatine kinase, lactate dehydrogenase (LDH), C-terminal telopeptide of type Ⅰ collagen (CTX-Ⅰ), C-terminal telopeptide of type Ⅱ collagen (CTX-Ⅱ), cartilage oligomeric matrix protein (COMP), and calcium ions. {L-End}Results The RPE scores of the study subjects for the muscles of five body parts and the whole body increased with the increasing lifting periods (all P<0.01). Fatigue was observed in all target muscles, with overall body fatigue occurring in the T2 period. The levels of ammonia, lactate, creatine kinase, LDH, COMP, and calcium ions in the serum of study subjects were higher in the T1 to T4 periods than in the T0 period (all P<0.05). The serum CTX-Ⅰ level was higher in the T1 and T3 periods than that in the T0 period (all P<0.05) , and the serum CTX-Ⅱ level was higher in the T1, T2 and T4 periods than that in the T0 period (all P<0.05). The level of these eight serum metabolic biomarkers fluctuated during the T1 to T4 periods. The serum creatine kinase level increased with the period of lifting (all P<0.05). The serum lactate level was higher in the T3 period than those in the T1 and T2 periods (all P<0.05). The serum LDH and calcium ion levels were higher in the T2 to T4 periods than that in the T1 period (all P<0.05). The serum COMP level was higher in the T2 and T3 periods than that in the T1 period (all P<0.05). Except for CTX-Ⅰ, the levels of other seven metabolic markers in serum were higher in individuals after fatigue than before fatigue (all P<0.05). {L-End}Conclusion Serum metabolic biomarkers such as ammonia, lactate, creatine kinase, calcium ions, LDH, CTX-Ⅱ, and COMP exhibit significant changes before and after fatigue. These metabolic biomarkers could be used as sensitive biomarkers for evaluating muscle fatigue during repetitive works.

Cartilage Oligomeric Matrix Protein, Diseases, and Therapeutic Opportunities.

Cartilage oligomeric matrix protein (COMP) is an extracellular matrix (ECM) glycoprotein that is critical for collagen assembly and ECM stability. Mutations of COMP cause endoplasmic reticulum stress and chondrocyte apoptosis, resulting in rare skeleton diseases. The bouquet-like structure of COMP allows it to act as a bridging molecule that regulates cellular phenotype and function. COMP is able to interact with many other ECM components and binds directly to a variety of cellular receptors and growth factors. The roles of COMP in other skeleton diseases, such as osteoarthritis, have been implied. As a well-established biochemical marker, COMP indicates cartilage turnover associated with destruction. Recent exciting achievements indicate its involvement in other diseases, such as malignancy, cardiovascular diseases, and tissue fibrosis. Here, we review the basic concepts of COMP and summarize its novel functions in the regulation of signaling events. These findings renew our understanding that COMP has a notable function in cell behavior and disease progression as a signaling regulator. Interestingly, COMP shows distinct functions in different diseases. Targeting COMP in malignancy may withdraw its beneficial effects on the vascular system and induce or aggravate cardiovascular diseases. COMP supplementation is a promising treatment for OA and aortic aneurysms while it may induce tissue fibrosis or cancer metastasis.

Upregulation of Cartilage Oligomeric Matrix Protein Predicts Poor Prognosis in Urothelial Carcinoma.

Purpose: Cartilage oligomeric matrix protein (COMP) is known as a large pentameric glycoprotein, which interacts with various extracellular matrix proteins in tissues. COMP has been reported to play a role in multiple connective tissue disorders. Recently, elevated COMP levels have been found to be associated with increased tumor size, metastases, faster recurrence of cancer, and overall poorer survival in several cancers. However, the clinical importance of COMP in urothelial carcinoma remains unclear. We investigated the association between COMP expression and clinical outcomes in urothelial carcinoma. Patients and Methods: In this retrospective study, we collected urothelial carcinoma (UC) tissue from 340 upper urinary tract UC (UTUC) patients and 295 urinary bladder UC (UBUC) patients. Pearson's chi-square test, Kaplan-Meier analysis, and the multivariate Cox proportional hazards model was used to examine the relationship between COMP expression and patient characteristics, pathological findings, and patient survival, such as metastasis-free survival (MFS) and disease-specific survival (DSS). Results: A total of 295 UBUC patients and 340 UTUC patients were recruited. The COMP mRNA level was significantly higher among invasive tumors (pT2-pT4) than in noninvasive tumors (pTa-T1) in UBUC groups (P < 0.01). COMP overexpression was associated with advanced T stage, nodal metastases, vascular invasion, perineural invasion, high histological grade, and high mitotic rate in both UBUC and UTUC cohorts. COMP overexpression was predictive of shorter DSS (hazard ratio [HR] in UBUC, 3.986, P < 0.001; in UTUC, 2.283, P = 0.027] and MFS (HR in UBUC, 6.813, P < 0.001; in UTUC, 4.070, P < 0.001). Kaplan-Meier analysis demonstrated high COMP expression associated with poor DSS and MFS in UTUC and UBUC groups (all P < 0.0001). Conclusion: COMP overexpression was linked to poor clinical prognosis and poor pathological features in UC. These results suggest COMP as a biomarker for UC.

[Development of a fluorescence immunochromatography for quantitative detection of cartilage oligomeric matrix protein].

The purpose of this study was to develop a fluorescence chromatography method for the detection of cartilage oligomeric matrix protein (COMP) in the auxiliary diagnosis of rheumatoid arthritis (RA). The principle of double antibody sandwich method was used to prepare immunochromatographic test strips, and the performance evaluation and methodological comparison were carried out. Through the detection of clinical samples, a receiver operating characteristic (ROC) curve was obtained, and the sensitivity, specificity, positive and negative predictive values of the test strip were calculated. The linear range was 0.39-50.00 ng/mL. The coefficients of variation inter and intra batches were less than 15%. The test strip was stable at 37 ℃ for 20 days, and the variation range of fluorescence signal intensity was within 15%. There was no cross reaction with rheumatoid factor (RF) and anti-cyclic citrulline peptide (anti-CCP) antibody. Forty-eight clinical serum samples were detected in parallel with ELISA kit, and the correlation was good. The test strip prepared in this study was used to detect the sample, the cut-off value of COMP between RA patients and healthy people was 22.55 ng/mL (sensitivity 0.821, specificity 0.842, positive predictive value 0.741, negative predictive value 0.895). At the same time, the same sample was tested with ELISA kit, the sensitivity and specificity of the two methods reached more than 80%. A quantitative COMP fluorescence chromatography test strip was developed, which has the advantages of celerity, simplicity and sensitivity, and may provide rapid auxiliary diagnosis for RA patients.