Expression of CHI3L1 and CHIT1 in osteoarthritic rat cartilage model. A morphological study

Transcriptomic analysis reveals distinct molecular signatures and regulatory networks of osteoarthritic chondrocytes versus mesenchymal stem cells during chondrogenesis

BACKGROUND

Recent regenerative studies imply conflicting results on knee osteoarthritic (OA) chondrocytes and mesenchymal stem cells (MSC)-mediated cartilage constructs in terms of compressive properties and tensile strength. This could be attributed to different gene expression patterns between MSC and OA chondrocytes during chondrogenic differentiation. Therefore, we analyzed differentially expressed genes (DEGs) between OA and MSC-derived chondrocytes using bioinformatics tools.

METHODS

We downloaded and analyzed the GSE19664 dataset from the Gene Expression Omnibus to identify DEGs. DAVID was used to perform Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses, while a protein-protein interaction network of DEGs was constructed through the Search Tool for the Retrieval of Interacting Genes (STRING) and identified hub genes by CytoHubba.

RESULTS

A total of 43 DEGs identified (15 downregulated and 28 upregulated) were found to be deregulated between OA and MSC-derived chondrocytes. KEGG analysis revealed the enrichment of complement and coagulation cascades and other pathways among the studied chondrocytes. The pathway enrichment identified top KEGG, gene ontology biological process, molecular function, and cellular component. The hub networks identified the top 5 hub genes involved in chondrogenesis, including CLU, PLAT, CP, TIMP3, and SERPINA1.

CONCLUSIONS

Our results identified significant genes involved in chondrogenesis. These findings provide new avenues for exploring the genetic mechanism underlying cartilage synthesis and novel targets for preclinical intervention and clinical treatment.

Palmatine, an isoquinoline alkaloid from Phellodendron amurense Rupr., ameliorated gouty inflammation by inhibiting pyroptosis via NLRP3 inflammasome

ETHNOPHARMACOLOGICAL RELEVANCE

Palmatine (Pal), derived from Daemonorops margaritae (Hance) Becc and Phellodendron amurense Rupr. is a natural isoquinoline alkaloid widely used in clearing heat and drying dampness, purging the pathogenic fire and removing symptoms, detoxifying toxins and healing sores.

AIM OF THE STUDY

Gout is a common metabolic inflammatory disease caused by the deposition of MSU crystals (MSU) in joints and non-articulation structures. Given the multiple toxic side effects of clinical anti-gout medications, there is a need to find a safe and effective alternative. We investigated the therapeutic effects of Pal on MSU crystal-induced acute gouty inflammation, targeting the NLRP3 inflammasome mediated pyroptosis.

MATERIALS AND METHODS

In vitro, mouse peritoneal macrophages (MPM) and rat articular chondrocytes were stimulated with LPS plus MSU in the presence or absence of Palmatine. In vivo, arthritis models include the acute gouty arthritis model by injecting MSU crystals in the paws of mice and the air pouch acute gout model by injecting MSU crystals into the mouse subcutaneous tissue of the back. Expression of NLRP3 inflammasome activation and NETosis formation was determined by Western blot, ELISA kit, immunohistochemistry, and immunofluorescence. In addition, the anti-cartilage damage of Palmatine on MSU-induced arthritis mice were also evaluated.

RESULTS

Pal dose-dependently decreased levels of NLRP3 inflammasome activation related proteins NLRP3, ASC, caspase-1, IL-1β, HMGB1 and Cathepsin B. The NETosis protein levels of caspase-11, histone3, PR3 and PAD4 were remarkably reduced by Pal. Pal effectively blocked the activation of NLRP3 inflammasome, attenuated the caspase-11 mediated noncanonical NLRP3 inflammasome activation and intervened the formation of NETs, thereby inhibiting the pyroptosis. In vivo, Pal attenuated MSU-induced inflammation in gouty arthritis and protect the articular cartilage through inhibiting the pyroptosis of proteins NLRP3, ASC, caspase-1, IL-1β, HMGB1 and Cathepsin B, reducing levels of NETosis relevant proteins caspase-11, histone3, PR3 and PAD4 and up-regulating expression of protein MMP-3.

CONCLUSION

Palmatine ameliorated gouty inflammation by inhibiting pyroptosis via NLRP3 inflammasome.

Recently Updated Role of Chitinase 3-like 1 on Various Cell Types as a Major Influencer of Chronic Inflammation

Chitinase 3-like 1 (also known as CHI3L1 or YKL-40) is a mammalian chitinase that has no enzymatic activity, but has the ability to bind to chitin, the polymer of N-acetylglucosamine (GlcNAc). Chitin is a component of fungi, crustaceans, arthropods including insects and mites, and parasites, but it is completely absent from mammals, including humans and mice. In general, chitin-containing organisms produce mammalian chitinases, such as CHI3L1, to protect the body from exogenous pathogens as well as hostile environments, and it was thought that it had a similar effect in mammals. However, recent studies have revealed that CHI3L1 plays a pathophysiological role by inducing anti-apoptotic activity in epithelial cells and macrophages. Under chronic inflammatory conditions such as inflammatory bowel disease and chronic obstructive pulmonary disease, many groups already confirmed that the expression of CHI3L1 is significantly induced on the apical side of epithelial cells, and activates many downstream pathways involved in inflammation and carcinogenesis. In this review article, we summarize the expression of CHI3L1 under chronic inflammatory conditions in various disorders and discuss the potential roles of CHI3L1 in those disorders on various cell types.

Baicalin Maintains Articular Cartilage Homeostasis and Alleviates Osteoarthritis by Activating FOXO1

Baicalin has been acknowledged for its anti-inflammatory properties. However, its potential impact on osteoarthritis (OA) has not yet been explored. Therefore, our study aimed to examine the effects of Baicalin on OA, both in laboratory and animal models. To evaluate its efficacy, human chondrocytes affected by OA were treated with interleukin-1β and/or Baicalin. The effects were then assessed through viability tests using the cell counting kit-8 (CCK-8) method and flow cytometry. In addition, we analyzed the expressions of various factors such as FOXO1, autophagy, apoptosis, and cartilage synthesis and breakdown to corroborate the effects of Baicalin. We also assessed the severity of OA through analysis of tissue samples. Our findings demonstrate that Baicalin effectively suppresses inflammatory cytokines and MMP-13 levels caused by collagenase-induced osteoarthritis, while simultaneously preserving the levels of Aggrecan and Col2. Furthermore, Baicalin has been shown to enhance autophagy. Through the use of FOXO1 inhibitors, lentivirus-mediated knockdown, and chromatin immunoprecipitation, we verified that Baicalin exerts its protective effects by activating FOXO1, which binds to the Beclin-1 promoter, thereby promoting autophagy. In conclusion, our results show that Baicalin has potential as a therapeutic agent for treating OA (Clinical Trial Registration number: 2023-61).

Exosomes derived from MSC as drug system in osteoarthritis therapy

Osteoarthritis (OA) is the most common degenerative disease of the joint with irreversible cartilage damage as the main pathological feature. With the development of regenerative medicine, mesenchymal stem cells (MSCs) have been found to have strong therapeutic potential. However, intraarticular MSCs injection therapy is limited by economic costs and ethics. Exosomes derived from MSC (MSC-Exos), as the important intercellular communication mode of MSCs, contain nucleic acid, proteins, lipids, microRNAs, and other biologically active substances. With excellent editability and specificity, MSC-Exos function as a targeted delivery system for OA treatment, modulating immunity, inhibiting apoptosis, and promoting regeneration. This article reviews the mechanism of action of MSC-Exos in the treatment of osteoarthritis, the current research status of the preparation of MSC-Exos and its application of drug delivery in OA therapy.

Pregnancy related factors and temporomandibular disorders evaluated through the diagnostic criteria for temporomandibular disorders (DC/TMD) axis II: a cross sectional study

INTRODUCTION

Temporomandibular disorder (TMD) is a multifaceted condition impacting the chewing system, with its frequency varying across different age groups and showing a higher incidence in women. The involvement of estrogen in TMD has been examined due to the presence of estrogen receptors in the TMJ area. However, the exact effect of estrogen on TMD is complex. During pregnancy, marked by significant hormonal fluctuations, the impact on TMD has been hypothesized but remains unclear due to inconsistent results from various studies.

METHODS

In this cross-sectional study, we enrolled 32 pregnant women consecutively. We gathered information on demographics, TMD evaluations (using the Graded Chronic Pain Scale, Jaw Functional Limitation Scale-20, and Oral Behaviors Checklist), and mental health assessments (including Patient Health Questionnaire-9, Patient Health Questionnaire-15, and Generalized Anxiety Disorder-7). We employed descriptive statistics to summarize continuous and categorical data and used t-tests and chi-square tests for comparisons. We also conducted multivariate linear regression, adjusted for demographic factors, to investigate correlations.

RESULTS

The study group mainly consisted of women aged 30-35 (40.6%) and 25-30 (18.8%). Most participants had completed high school (50%) and were married (71.9%). A notable association was found between younger women (under 30) and higher levels of somatic symptoms (p = 0.008) and generalized anxiety (p = 0.015). Women in their second trimester showed lower severity of somatic symptoms (p = 0.04). A significant link was also observed between depression severity and somatic symptom severity (p = 0.01). However, we found no significant correlations with other TMD-related health aspects.

DISCUSSION

Our study identified significant associations between psychosomatic and psychological symptoms with variables like age and pregnancy trimester in pregnant women. However, it notably failed to establish a clear relationship between pregnancy-related factors and the severity of temporomandibular disorders (TMD). More comprehensive studies with larger participant pools are necessary to further validate and expand these findings.

Significance of chitinase-3-like protein 1 in the pathogenesis of inflammatory diseases and cancer

Chitinase-3-like protein 1 (CHI3L1) is a secreted glycoprotein that mediates inflammation, macrophage polarization, apoptosis, and carcinogenesis. The expression of CHI3L1 is strongly upregulated by various inflammatory and immunological diseases, including several cancers, Alzheimer's disease, and atherosclerosis. Several studies have shown that CHI3L1 can be considered as a marker of disease diagnosis, prognosis, disease activity, and severity. In addition, the proinflammatory action of CHI3L1 may be mediated via responses to various proinflammatory cytokines, including tumor necrosis factor-α, interleukin-1β, interleukin-6, and interferon-γ. Therefore, CHI3L1 may contribute to a vast array of inflammatory diseases. However, its pathophysiological and pharmacological roles in the development of inflammatory diseases remain unclear. In this article, we review recent findings regarding the roles of CHI3L1 in the development of inflammatory diseases and suggest therapeutic approaches that target CHI3L1.

Cardamonin protects against iron overload induced arthritis by attenuating ROS production and NLRP3 inflammasome activation via the SIRT1/p38MAPK signaling pathway

Iron homeostasis plays an essential role in joint health, while iron overload can cause damage and death of cartilage cells. Cardamonin (CAR) is a substance found in the fruit of the chasteberry plant and has anti-inflammatory and anti-tumor activities. We first administered iron dextran (500 mg/kg) intraperitoneally to establish an iron overload mouse model and surgically induced osteoarthritis. The extent of OA and iron deposition were assessed using Micro-ct, Safranin-O/fast green staining, H&E staining, and Prussian Blue 10 weeks later. We administered primary chondrocytes with Ferric Ammonium Citrate (FAC) to evaluate the chondrocyte changes. Chondrocytes were identified in vitro by toluidine blue staining, and chondrocyte viability was evaluated by CCK-8. The rate of apoptosis was determined by Annexin V-FITC/PI assay. The mechanism of action of CAR was verified by adding the SIRT1 inhibitor EX527, and the expression of SIRT1 and MAPK signaling pathways was detected by Western blot. Iron overload also promoted chondrocyte apoptosis, a process that was reversed by CAR. In addition, CAR reduced NLRP3 inflammasome production via the SIRT1-MAPK pathway, and the SIRT1 inhibitor EX527 inhibited the treatment of OA by CAR.CAR inhibited cartilage degeneration induced by iron overload both in vivo and in vitro. Besides, our study showed that iron overload not only inhibited type II collagen expression but also induced MMP expression by catalyzing the generation of NLRP3 inflammasome. Our results suggest that CAR can treat KOA by promoting SIRT1 expression and inhibiting p38MAPK pathway expression to reduce the production of NLRP3 inflammasome vesicles.

Obesity defined molecular endotypes in the synovium of patients with osteoarthritis provides a rationale for therapeutic targeting of fibroblast subsets

BACKGROUND

Osteoarthritis (OA), a multifaceted condition, poses a significant challenge for the successful clinical development of therapeutics due to heterogeneity. However, classifying molecular endotypes of OA pathogenesis could provide invaluable phenotype-directed routes for stratifying subgroups of patients for targeted therapeutics, leading to greater chances of success in trials. This study establishes endotypes in OA soft joint tissue driven by obesity in both load-bearing and non-load bearing joints.

METHODS

Hand, hip, knee and foot joint synovial tissue was obtained from OA patients (n = 32) classified as obese (BMI > 30) or normal weight (BMI 18.5-24.9). Isolated fibroblasts (OA SF) were assayed by Olink proteomic panel, seahorse metabolic flux assay, Illumina's NextSeq 500 bulk and Chromium 10X single cell RNA-sequencing, validated by Luminex and immunofluorescence.

RESULTS

Targeted proteomic, metabolic and transcriptomic analysis found the inflammatory landscape of OA SFs are independently impacted by obesity, joint loading and anatomical site with significant heterogeneity between obese and normal weight patients, confirmed by bulk RNAseq. Further investigation by single cell RNAseq identified four functional molecular endotypes including obesity specific subsets defined by an inflammatory endotype related to immune cell regulation, fibroblast activation and inflammatory signaling, with up-regulated CXCL12, CFD and CHI3L1 expression. Luminex confirmed elevated chitase3-like-1(229.5 vs. 49.5 ng/ml, p < .05) and inhibin (20.6 vs. 63.8 pg/ml, p < .05) in obese and normal weight OA SFs, respectively. Lastly, we find SF subsets in obese patients spatially localise in sublining and lining layers of OA synovium and can be distinguished by differential expression of the transcriptional regulators MYC and FOS.

CONCLUSION

These findings demonstrate the significance of obesity in changing the inflammatory landscape of synovial fibroblasts in both load bearing and non-load bearing joints. Describing multiple heterogeneous OA SF populations characterised by specific molecular endotypes, which drive heterogeneity in OA disease pathogenesis. These molecular endotypes may provide a route for the stratification of patients in clinical trials, providing a rational for the therapeutic targeting of specific SF subsets in specific patient populations with arthritic conditions.

Expression Profile of New Gene Markers Involved in Differentiation of Canine Adipose-Derived Stem Cells into Chondrocytes

The interest in stem cell research continuously increased over the last decades, becoming one of the most important trends in the 21st century medicine. Stem cell-based therapies have a potential to become a solution for a range of currently untreatable diseases, such as spinal cord injuries, type I diabetes, Parkinson’s disease, heart disease, stroke, and osteoarthritis. Hence, this study, based on canine material, aims to investigate the molecular basis of adipose-derived stem cell (ASC) differentiation into chondrocytes, to serve as a transcriptomic reference for further research aiming to introduce ASC into treatment of bone and cartilage related diseases, such as osteoarthritis in veterinary medicine. Adipose tissue samples were harvested from a canine specimen subjected to a routine ovariohysterecromy procedure at an associated veterinary clinic. The material was treated for ASC isolation and chondrogenic differentiation. RNA samples were isolated at day 1 of culture, day 30 of culture in unsupplemented culture media, and day 30 of culture in chondrogenic differentiation media. The resulting RNA was analyzed using RNAseq assays, with the results validated by RT-qPCR. Between differentiated chondrocytes, early and late cultures, most up- and down-regulated genes in each comparison were selected for further analysis., there are several genes (e.g., MMP12, MPEG1, CHI3L1, and CD36) that could be identified as new markers of chondrogenesis and the influence of long-term culture conditions on ASCs. The results of the study prove the usefulness of the in vitro culture model, providing further molecular insight into the processes associated with ASC culture and differentiation. Furthermore, the knowledge obtained could be used as a molecular reference for future in vivo and clinical studies.

Single-Cell RNA-Seq Analysis of Cells from Degenerating and Non-Degenerating Intervertebral Discs from the Same Individual Reveals New Biomarkers for Intervertebral Disc Degeneration

In this study, we used single-cell transcriptomic analysis to identify new specific biomarkers for nucleus pulposus (NP) and inner annulus fibrosis (iAF) cells, and to define cell populations within non-degenerating (nD) and degenerating (D) human intervertebral discs (IVD) of the same individual. Cluster analysis based on differential gene expression delineated 14 cell clusters. Gene expression profiles at single-cell resolution revealed the potential functional differences linked to degeneration, and among NP and iAF subpopulations. GO and KEGG analyses discovered molecular functions, biological processes, and transcription factors linked to cell type and degeneration state. We propose two lists of biomarkers, one as specific cell type, including C2orf40, MGP, MSMP, CD44, EIF1, LGALS1, RGCC, EPYC, HILPDA, ACAN, MT1F, CHI3L1, ID1, ID3 and TMED2. The second list proposes predictive IVD degeneration genes, including MT1G, SPP1, HMGA1, FN1, FBXO2, SPARC, VIM, CTGF, MGST1, TAF1D, CAPS, SPTSSB, S100A1, CHI3L2, PLA2G2A, TNRSF11B, FGFBP2, MGP, SLPI, DCN, MT-ND2, MTCYB, ADIRF, FRZB, CLEC3A, UPP1, S100A2, PRG4, COL2A1, SOD2 and MT2A. Protein and mRNA expression of MGST1, vimentin, SOD2 and SYF2 (p29) genes validated our scRNA-seq findings. Our data provide new insights into disc cells phenotypes and biomarkers of IVD degeneration that could improve diagnostic and therapeutic options.

Compatibility of Achyranthes bidentata components in reducing inflammatory response through Arachidonic acid pathway for treatment of Osteoarthritis

Achyranthes bidentate is a common traditional Chinese medicine (TCM) used in treating osteoarthritis (OA). The compatibility between effective components has now become a breakthrough in understanding the mechanism of TCM. This study aimed at determining the optimal compatibility and possible mechanism of Achyranthes bidentate for OA treatment. Results showed that the adhesion score of the OA group is higher than NC group, and showed a trend of down-regulation in the intervention group. The CHI3L1 and IL-1β in joint fluid of the OA group was significantly increased compared to the sham operation group (NC group). Group G, I, and L exhibited significantly down-regulated CHI3L1, while groups C, F, I, K, and L exhibited reduced IL-1β. Joint adhesion, damage in cartilage, and synovial tissue was found in the OA model, cartilage tissue was found recovered in groups I, J, and L, and synovial tissue was recovered in group G, I, and L. Thus, group I and L were chosen for metabolite analysis, and indole-3-propionic acid was slightly up-regulated, while koeiginequinone A, prostaglandin H2, and 1-hydroxy-3-methoxy-10-methylacridonew were down-regulated in group I and L. According to functional analysis, the arachidonic acid (AA) metabolic pathway is enriched. Down-regulated expression of vital proteins in the AA metabolism pathway, such as PGE2 and COX2 in group I and L were verified. In conclusion, Hydroxyecdysone, Oleanolic acid, Achyranthes bidentata polysaccharide at a compatibility of 0.03-μg/mg, 2.0-μg/mg, 20.0-μg/mg or 0.03-μg/mg, 2.0-μg/mg, 10.0-μg/mg, respectively, may be the optimal compatibility of Achyranthes bidentate.

Proteomic Analysis of Synovial Fibroblasts and Articular Chondrocytes Co-Cultures Reveals Valuable VIP-Modulated Inflammatory and Degradative Proteins in Osteoarthritis

Osteoarthritis (OA) is the most common musculoskeletal disorder causing a great disability and a reduction in the quality of life. In OA, articular chondrocytes (AC) and synovial fibroblasts (SF) release innate-derived immune mediators that initiate and perpetuate inflammation, inducing cartilage extracellular matrix (ECM) degradation. Given the lack of therapies for the treatment of OA, in this study, we explore biomarkers that enable the development of new therapeutical approaches. We analyze the set of secreted proteins in AC and SF co-cultures by stable isotope labeling with amino acids (SILAC). We describe, for the first time, 115 proteins detected in SF-AC co-cultures stimulated by fibronectin fragments (Fn-fs). We also study the role of the vasoactive intestinal peptide (VIP) in this secretome, providing new proteins involved in the main events of OA, confirmed by ELISA and multiplex analyses. VIP decreases proteins involved in the inflammatory process (CHI3L1, PTX3), complement activation (C1r, C3), and cartilage ECM degradation (DCN, CTSB and MMP2), key events in the initiation and progression of OA. Our results support the anti-inflammatory and anti-catabolic properties of VIP in rheumatic diseases and provide potential new targets for OA treatment.

M2a Macrophage-Secreted CHI3L1 Promotes Extracellular Matrix Metabolic Imbalances via Activation of IL-13Rα2/MAPK Pathway in Rat Intervertebral Disc Degeneration

The accumulation of macrophages in degenerated discs is a common phenomenon. However, the roles and mechanisms of M2a macrophages in intervertebral disc degeneration (IDD) have not been illuminated. This study investigated the expression of the M2a macrophage marker (CD206) in human and rat intervertebral disc tissues by immunohistochemistry. To explore the roles of M2a macrophages in IDD, nucleus pulposus (NP) cells were co-cultured with M2a macrophages in vitro. To clarify whether the CHI3L1 protein mediates the effect of M2a macrophages on NP cells, siRNA was used to knock down CHI3L1 transcription. To elucidate the underlying mechanisms, NP cells were incubated with recombinant CHI3L1 proteins, then subjected to western blotting analysis of the IL-13Rα2 receptor and MAPK pathway. CD206-positive cells were detected in degenerated human and rat intervertebral disc tissues. Notably, M2a macrophages promoted the expression of catabolism genes (MMP-3 and MMP-9) and suppressed the expression of anabolism genes (aggrecan and collagen II) in NP cells. These effects were abrogated by CHI3L1 knockdown in M2a macrophages. Exposure to recombinant CHI3L1 promoted an extracellular matrix metabolic imbalance in NP cells via the IL-13Rα2 receptor, along with activation of the ERK and JNK MAPK signaling pathways. This study elucidated the roles of M2a macrophages in IDD and identified potential mechanisms for these effects.

Brain CHID1 Expression Correlates with NRGN and CALB1 in Healthy Subjects and AD Patients

Alzheimer’s disease is a progressive, devastating, and irreversible brain disorder that, day by day, destroys memory skills and social behavior. Despite this, the number of known genes suitable for discriminating between AD patients is insufficient. Among the genes potentially involved in the development of AD, there are the chitinase-like proteins (CLPs) CHI3L1, CHI3L2, and CHID1. The genes of the first two have been extensively investigated while, on the contrary, little information is available on CHID1. In this manuscript, we conducted transcriptome meta-analysis on an extensive sample of brains of healthy control subjects (n = 1849) (NDHC) and brains of AD patients (n = 1170) in order to demonstrate CHID1 involvement. Our analysis revealed an inverse correlation between the brain CHID1 expression levels and the age of NDHC subjects. Significant differences were highlighted comparing CHID1 expression of NDHC subjects and AD patients. Exclusive in AD patients, the CHID1 expression levels were correlated positively to calcium-binding adapter molecule 1 (IBA1) levels. Furthermore, both in NDHC and in AD patient’s brains, the CHID1 expression levels were directly correlated with calbindin 1 (CALB1) and neurogranin (NRGN). According to brain regions, correlation differences were shown between the expression levels of CHID1 in prefrontal, frontal, occipital, cerebellum, temporal, and limbic system. Sex-related differences were only highlighted in NDHC. CHID1 represents a new chitinase potentially involved in the principal processes underlying Alzheimer’s disease.

CHI3L1 promotes Staphylococcus aureus-induced osteomyelitis by activating p38/MAPK and Smad signaling pathways

AIMS

Staphylococcus aureus (S. aureus) is the most common causative bacterial pathogen involved in promoting infection-induced osteomyelitis, a disease resulting in severe bone degradation. In this study, we aimed to identify the mechanism behind inhibition of osteoclast survival and differentiation by CHI3L1, a lectin previously reported to regulate S. aureus-induced osteomyelitis.

MAIN METHODS

The role of CHI3L1 in osteoclast survival, proliferation, and differentiation was studied ex vivo using primary human bone marrow derived stem cells (HBMSCs) and transducing them with lentiviral expression vectors or shRNA knockdown constructs. Cell apoptosis was analyzed by flow cytometry using annexin V-fluorescein isothiocyanate/propidium iodide staining. Cell proliferation was assessed using alkaline phosphatase, Alcian Blue, and TRAP staining. The qRT-PCR was used to measure mRNA levels of osteoclast maturation markers, and western blotting was used to analyze protein expression. An in vivo murine model for osteomyelitis and microcomputed tomography analyses of infected femurs were used to study the effects of CHI3L1 on bone erosion.

KEY FINDINGS

Overexpression of CHI3L1 significantly reduced HBMSC cell viability, proliferation, and differentiation, and knockdown improved these effects in the presence of S. aureus infection. More specifically, CHI3L1 constitutively activated the p38/MAPK pathway to promote apoptosis. Furthermore, CHI3L1 induced activation of the Smad pathway by promoting phosphorylation of Smad-1/5 proteins. Finally, overexpression of CHI3L1 significantly induced bone erosion upon S. aureus infection in a murine osteomyelitis model, and knockdown of CHI3L1 significantly alleviated this effect.

SIGNIFICANCE

CHI3L1 played a vital role in osteoblast differentiation and proliferation by regulating the p38/MAPK and Smad signaling pathways to promote S. aureus-induced osteomyelitis.

Postsynaptic damage and microglial activation in AD patients could be linked CXCR4/CXCL12 expression levels

Alzheimer's disease (AD) is one of the most common forms of dementia with still unknown pathogenesis. Several cytokines and chemokines are involved in the pathogenesis of AD. Among the chemokines, the CXCR4/CXCL12 complex has been shown to play an important role in the pathogenetic development of AD. We investigated the expression levels of CXCR4 / CXCL12 in fifteen brain regions of healthy non-demented subjects (NDHC) (2139 sample) and AD patients (1170 sample) stratified according to sex and age. Furthermore, we correlated their expressions with the Neurogranin (NRGN) and CHI3L1 levels, two inflamm-aging markers. We highlighted that CXCR4 gene expression levels were age-correlated in the brain of NDHC subjects and that AD nullified this correlation. A similar trend, but diametrically opposite was observed for CXCL12. Its expression was decreased during the aging in both sexes, and in the brains of AD patients, it underwent an inversion of the trend, only and exclusively in females. Brains of AD patients expressed high CXCR4 and CHI3L1, and low CXCL12 and Neurogranin levels compared to NDHC subjects. Both CXCR4 and CXCL12 correlated significantly with CHI3L1 and Neurogranin expression levels, regardless of disease. Furthermore, we showed a selective modulation of CXCL12 and CXCR4 only in specific brain regions. Taken together our results demonstrate that CXCL12 and CXCR4 are linked to Neurogranin and CHI3L1 expression levels and the relationship between postsynaptic damage and microglial activation in AD could be shown using all these genes. Further confirmations are needed to demonstrate the close link between these genes.

Cordycepin Alleviates Anterior Cruciate Ligament Transection (ACLT)-Induced Knee Osteoarthritis Through Regulating TGF-β Activity and Autophagy

Introduction

Osteoarthritis is the most prevalent articular disease in the elderly. We aimed to explore the role of cordycepin (COR) in the progression and development of osteoarthritis and its correlation with TGF-β activity and autophagy.

Methods

Sprague Dawley rats were induced by anterior cruciate ligament transection (ACLT) to establish knee osteoarthritis model. To investigate the role of COR in knee osteoarthritis, rats were injected with 5, 10, and 20 mg/kg of COR before joint surgery. After surgery, paw withdrawal mechanical threshold (PWMT) was performed. HE staining and Alcian blue staining were carried out to detect cartilage damage. ELISA was used to detect the level of TGFβ in the serum. Protein expression was analyzed by Western blotting.

Results

In this study, we found that the PWMT of rats with osteoarthritis induced by ACLT was decreased significantly, accompanied by obvious histological and cartilage damage. After different doses of COR treatment, the PWMT of osteoarthritis rats induced by ACLT was increased in a dose-dependent manner. In addition, compared with the control group, COR treatment also reversed the effect of ACLT on cartilage injury in rats. Furthermore, the level of TGF-β in serum of ACLT rats was increased significantly, which may be related to the overexpression of TGF-β R1. However, the increase of serum TGF-β level in ACLT rats was reversed by COR treatment in a dose-dependent manner. It is worth noting that TGF-β overexpression reduced the proportion of autophagy-related protein LC3-II/I, thus inhibiting autophagy. In order to further confirm the effect of TGF-β on autophagy, TGF-β was overexpressed or the autophagy inhibitor 3-MA was applied. The results showed that TGF-β overexpression and 3-MA treatment reversed the effect of COR on autophagy.

Conclusion

In summary, our findings declared that COR alleviated ACLT-induced osteoarthritis pain and cartilage damage by inhibiting TGF-β activity and inducing autophagy in rat model with knee osteoarthritis.

CHI3L2 Expression Levels Are Correlated with AIF1, PECAM1, and CALB1 in the Brains of Alzheimer's Disease Patients

Alzheimer's disease (AD) represents one of the main forms of dementia that afflicts our society. The expression of several genes has been associated with disease development. Despite this, the number of genes known to be capable of discriminating between AD patients according to sex remains deficient. In our study, we performed a transcriptomes meta-analysis on a large court of brains of healthy control subjects (n = 2139) (NDHC) and brains of AD patients (n = 1170). Our aim was to verify the brain expression levels of CHI3L2 and its correlation with genes associated with microglia-mediated neuroinflammation (IBA1), alteration of the blood-brain barrier (PECAM1), and neuronal damage (CALB1). We showed that the CHI3L2, IBA1, PECAM1, and CALB1 expression levels were modulated in the brains of patients with AD compared to NDHC subjects. Furthermore, both in NDHC and in AD patient's brains, the CHI3L2 expression levels were directly correlated with IBA1 and PECAM1 and inversely with CALB1. Additionally, the expression levels of CHI3L2, PECAM1, and CALB1 but not of IBA1 were sex-depended. By stratifying the samples according to age and sex, correlation differences emerged between the expression levels of CHI3L2, IBA1, PECAM1, and CALB1 and the age of NDHC subjects and AD patients. CHI3L2 represents a promising gene potentially involved in the key processes underlying Alzheimer's disease. Its expression in the brains of sex-conditioned AD patients opens up new possible sex therapeutic strategies aimed at controlling imbalance in disease progression.

Baicalin Protects Human OA Chondrocytes Against IL-1β-Induced Apoptosis and ECM Degradation by Activating Autophagy via MiR-766-3p/AIFM1 Axis

Background

Osteoarthritis (OA) is one of the most prevalent and degenerative diseases with complicated pathology including articular cartilage degradation, subchondral sclerosis and synovitis. Chondrocytes play a crucial role in maintaining cartilage integrity.

Methods

Primary chondrocytes were treated with 10 ng/mL IL-1β alone, or pre-treated with 20 μM baicalin for 5 h followed by co-treatment with 20 μM baicalin and 10 ng/mL IL-1β. CCK-8 assay was used to assess cell viability, and cell apoptosis was analyzed by both PI/FITC-Annexin V staining and quantitating apoptosis-related Bcl-2, Bax and cleaved-caspase-3 expression at both protein and mRNA level by Western blotting and qRT-PCR, respectively. Chondrocytes were transfected with miRNA-766-3p mimic and autophagy flux was examined by LC3, Beclin and p62 Western blotting and by Cyto-ID assay to quantify autophagic vacuoles.

Results

Baicalin treatment decreased the apoptosis rate and the expressions of pro-apoptotic proteins induced by IL-1β, up-regulated anti-apoptotic Bcl-2 expression, and inhibited the degradation of ECM. Baicalin increased autophagy through up-regulating the autophagy markers Beclin-1 expression and LC3 Ⅱ/LC3 Ⅰ ratio and promoting autophagic flux. Contrarily, autophagy inhibition partially alleviated the beneficial effects of baicalin on ECM synthesis and anti-apoptosis in the chondrocytes treated with L-1β. Furthermore, the differential expressional profiles of miR-766-3p and apoptosis-inducing factor mitochondria-associated 1 (AIFM1) were determined in IL-1β and IL-1β + baicalin-treated chondrocytes, and we confirmed AIFM1 was a target of miR-766-3p. MiR-766-3p overexpression suppressed apoptosis and facilitated autophagy and ECM synthesis in the chondrocytes through decreasing AIFM1. Contrarily, silencing of miR-766-3p inhibited chondrocyte autophagy and promoted apoptosis, and this effect could be reversed by AIFM1 silence.

Conclusion

Baicalin protects human OA chondrocytes against IL-1β-induced apoptosis and the degradation of ECM through activating autophagy via miR-766-3p/AIFM1 axis and serves as a potential therapeutic candidate for OA treatment.

Current knowledge of pituitary adenylate cyclase activating polypeptide (PACAP) in articular cartilage

Pituitary adenylate cyclase activating polypeptide (PACAP) is an evolutionally well conserved neuropeptide, mainly expressed by neuronal and peripheral cells. It proves to be an interesting object of study both for its trophic functions during the development of several tissues and for its protective effects against oxidative stress, hypoxia, inflammation and apoptosis in different degenerative diseases. This brief review summarises the recent findings concerning the role of PACAP in the articular cartilage. PACAP and its receptors are expressed during chondrogenesis and are shown to activate the pathways involved in regulating cartilage development. Moreover, this neuropeptide proves to be chondroprotective against those stressors that determine cartilage degeneration and contribute to the onset of osteoarthritis (OA), the most common form of degenerative joint disease. Indeed, the degenerated cartilage exhibits low levels of PACAP, suggesting that its endogenous levels in adult cartilage may play an essential role in maintaining physiological properties. Thanks to its peculiar characteristics, exogenous administration of PACAP could be suggested as a potential tool to slow down the progression of OA and for cartilage regeneration approaches.

Research and Publication Ethics in Journal of Functional Morphology and Kinesiology

Research is required to minimize uncertainty and to be reproducible, that is, the design, implementation, evaluation, interpretation, and reporting of the presented data, must follow a good practice. An appropriate experimental design, an accurate execution of the study, a strict criticism of the obtained data while avoiding overestimation, as well as a suitable interpretation of main outcomes, represent key aspects in reporting and disseminating research to the scientific community. Furthermore, author contribution, responsibility, funding, acknowledgement, and adequately declaring any conflict of interest play important roles in science. The Journal of Functional Morphology and Kinesiology (JFMK), a member of the Committee on Publication Ethics (COPE), is committed to the highest scientific and ethical standards and encourages all authors to take into account and to comply, as much as possible, with the contents and issues reported in this technical note. This could be useful to improve the quality of the manuscripts and avoid misconduct, as well as to stimulate interest and debate, reflecting upon uses and misuses within our disciplines belonging to the medicine area (sports medicine and movement sciences) categories: anatomy, histology, orthopedics and sports medicine, rheumatology, sports sciences, physical therapy, sports therapy, and rehabilitation.

Craniomandibular Disorders in Pregnant Women: An Epidemiological Survey

Temporomandibular joint (TMJ) disorder has been reported to be 1.5 to two times more common in women than men. Such a gender-based difference could be attributed to behavioral, hormonal, anatomical, and psychological characteristics. Physiological hormonal differences between genders could be one of the possible explanations for the higher incidence of temporomandibular disorder (TMD) in women. As the plasma level of certain female hormones increases during gestation, it could be assumed that there is a higher prevalence of dysfunctional signs and symptoms in pregnant women. We performed an epidemiological survey based on screening for TMD in a group of 108 pregnant women and found that 72% of young women reported significant signs of TMJ disorders, 9% of the young women reported mild signs of TMJ disorders, and 19% of the included subjects reported no signs or symptoms of TMD. The presence of estrogen receptors in the temporomandibular joint of female baboons could be the basis of an explanation for the increased prevalence of dysfunction in young women reported in the literature and the high feedback we have seen of joint noises in pregnant women. On the basis of the present findings, it could be assumed that gestation period could represent a risk factor for craniomandibular dysfunctions.

The expression levels of CHI3L1 and IL15Rα correlate with TGM2 in duodenum biopsies of patients with celiac disease

OBJECTIVE AND DESIGN

Celiac disease (CD) is an intestinal inflammatory disorder of the small intestine. Gliadins are a component of gluten and there are three main types (α, γ, and ω). Recent studies indicate that gliadin peptides are able to activate an innate immune response. IL15 is a major mediator of the innate immune response and is involved in the early alteration of CD mucosa. The chitinase molecules are highly expressed by the innate immune cells during the inflammatory processes.

MATERIAL OR SUBJECTS

We analyzed several microarray datasets of PBMCs and duodenum biopsies of CD patients and healthy control subjects (HCs). We verified the modulation CHI3L1 in CD patients and correlated the expression levels to the IL15, IL15Rα, TGM2, IFNγ, and IFNGR1/2. Duodenal biopsy samples belonged to nine active and nine treated children patients (long-term effects of gliadin), and 17 adult CD patients and 10 adults HCs. We also selected 169 samples of PBMCs from 127 CD patients on adherence to a gluten-free diet (GFD) for at least 2 years and 44 HCs.

RESULTS

Our analysis showed that CHI3L1 and IL15Rα were significantly upregulated in adult and children's celiac duodenum biopsies. In addition, the two genes were correlated significantly both in children than in adults CD duodenum biopsies. No significant modulation was observed in PBMCs of adult CD patients compared to the HCs. The correlation analysis of the expression levels of CHI3L1 and IL15Rα compared to TGM showed significant values both in adults and in children duodenal biopsies. Furthermore, the IFNγ expression levels were positively correlated with CHI3L1 and IL15Rα. Receiver operating characteristic (ROC) analysis confirmed the diagnostic ability of CHI3L1 and IL15Rα to discriminate CD from HCs.

CONCLUSION

Our data suggest a role for CHI3L1 underlying the pathophysiology of CD and represent a starting point aiming to inspire new investigation that proves the possible use of CHI3L1 as a diagnostic factor and therapeutic target.

Evaluation of a Cell-Free Collagen Type I-Based Scaffold for Articular Cartilage Regeneration in an Orthotopic Rat Model

The management of chondral defects represents a big challenge because of the limited self-healing capacity of cartilage. Many approaches in this field obtained partial satisfactory results. Cartilage tissue engineering, combining innovative scaffolds and stem cells from different sources, emerges as a promising strategy for cartilage regeneration. The aim of this study was to evaluate the capability of a cell-free collagen I-based scaffold to promote cartilaginous repair after orthotopic implantation in vivo. Articular cartilage lesions (ACL) were created at the femoropatellar groove in rat knees and cell free collagen I-based scaffolds (S) were then implanted into right knee defect for the ACL-S group. No scaffold was implanted for the ACL group. At 4-, 8- and 16-weeks post-transplantation, degrees of cartilage repair were evaluated by morphological, histochemical and gene expression analyses. Histological analysis shows the formation of fibrous tissue, at 4-weeks replaced by a tissue resembling the calcified one at 16-weeks in the ACL group. In the ACL-S group, progressive replacement of the scaffold with the newly formed cartilage-like tissue is shown, as confirmed by Alcian Blue staining. Immunohistochemical and quantitative real-time PCR (qRT-PCR) analyses display the expression of typical cartilage markers, such as collagen type I and II (ColI and ColII), Aggrecan and Sox9. The results of this study display that the collagen I-based scaffold is highly biocompatible and able to recruit host cells from the surrounding joint tissues to promote cartilaginous repair of articular defects, suggesting its use as a potential approach for cartilage tissue regeneration.

New Insights on Mechanical Stimulation of Mesenchymal Stem Cells for Cartilage Regeneration

Successful tissue regeneration therapies require further understanding of the environment in which the cells are destined to be set. The aim is to structure approaches that aspire to a holistic view of biological systems and to scientific reliability. Mesenchymal stem cells represent a valuable resource for cartilage tissue engineering, due to their chondrogenic differentiation capacity. Promoting chondrogenesis, not only by growth factors but also by exogenous enhancers such as biomechanics, represents a technical enhancement. Tribological evaluation of the articular joint has demonstrated how mechanical stimuli play a pivotal role in cartilage repair and participate in the homeostasis of this tissue. Loading stresses, physiologically experienced by chondrocytes, can upregulate the production of proteins like glycosaminoglycan or collagen, fundamental for articular wellness, as well as promote and preserve cell viability. Therefore, there is a rising interest in the development of bioreactor devices that impose compression, shear stress, and hydrostatic pressure on stem cells. This strategy aims to mimic chondrogenesis and overcome complications like hypertrophic phenotyping and inappropriate mechanical features. This review will analyze the dynamics inside the joint, the natural stimuli experienced by the chondrocytes, and how the biomechanical stimuli can be applied to a stem cell culture in order to induce chondrogenesis.

Downregulation of miR-34a Promotes Proliferation and Inhibits Apoptosis of Rat Osteoarthritic Cartilage Cells by Activating PI3K/Akt Pathway

Objective

To elucidate the expression and function of miR-34a in rat osteoarthritic cartilage cells, and further to explore its mechanism.

Material and Methods

Rat model of osteoarthritis was constructed and knee joint cartilage cells were isolated in vitro. Immunocytochemical staining was used for identification. qRT-PCR was used to detect the expression of miR-34a in cartilaginous tissues and cartilage cells. Cartilage cells were divided into blank control (BC), negative control (NC), miR-34a inhibitor (34aI), osteoarthritis model (OA), osteoarthritis model + negative control (OA + NC) and osteoarthritis model + miR-34a inhibitor (OA + 34aI) groups. Cell proliferation was detected by CCK-8 and colony formation assays. Cell apoptosis was studied by flow cytometry and Western blot. PI3K/AKT-pathway-related proteins were also analyzed by Western blot. To further validate the effect of miR-34a on the PI3K/Akt pathway, the cartilage cells were divided into blank control (BC), osteoarthritis model (OA), osteoarthritis model + miR-34a inhibitor (OA + 34aI), osteoarthritis model + PI3K activator (OA + IGF-1) and osteoarthritis model + miR-34a inhibitor + PI3K inhibitor (OA + 34aI + LY) groups, the experiments above were repeated.

Results

The expression of miR-34a in cartilaginous tissues and cells of osteoarthritis model was significantly higher than that in normal (p < 0.05). After silencing miR-34a gene, the cell proliferation and proteins expression of PI3K/Akt pathway were increased, while the apoptosis rate and expression of apoptosis-related proteins were decreased. Addition of PI3K activator also evidently promoted proliferation and inhibited apoptosis. The protein expression of Bax, Cleaved caspase-3 and Cleaved caspase-9 were dramatically decreased, while the ratios of p-PI3K/PI3K and p-Akt/Akt were increased in OA + IGF-1 group.

Conclusion

Downregulation of miR-34a regulated proliferation and apoptosis of cartilage cells by activating PI3K/Akt pathway, providing a potential therapeutic approach for the treatment of osteoarthritis.

COL2A1 and Caspase-3 as Promising Biomarkers for Osteoarthritis Prognosis in an Equus asinus Model

Osteoarthritis (OA) is one of the most degenerative joint diseases in both human and veterinary medicine. The objective of the present study was the early diagnosis of OA in donkeys using a reliable grading of the disease based on clinical, chemical, and molecular alterations. OA was induced by intra-articular injection of 25 mg monoiodoacetate (MIA) as a single dose into the left radiocarpal joint of nine donkeys. Animals were clinically evaluated through the assessment of lameness score, radiographic, and ultrasonographic findings for seven months. Synovial fluid and cartilage samples were collected from both normal and diseased joints for the assessment of matrix metalloproteinases (MMPs) activity, COL2A1 protein expression level, and histopathological and immunohistochemical analysis of Caspase-3. Animals showed the highest lameness score post-induction after one week then decreased gradually with the progression of radiographical and ultrasonographic changes. MMP activity and COL2A1 and Caspase-3 expression increased, accompanied by articular cartilage degeneration and loss of proteoglycan. OA was successfully graded in Egyptian donkeys, with the promising use of COL2A1and Caspase-3 for prognosis. However, MMPs failed to discriminate between early and late grades of OA.

Investigating lubricin and known cartilage-based biomarkers of osteoarthritis

Introduction: Osteoarthritis (OA) is a degenerative disease which primarily affects hyaline cartilage, leading to pain, stiffness and loss of mobility of the entire articulation. Diagnosis is commonly based on symptoms and radiographs, but there is a growing interest in detecting novel biomarkers, in serum, urine and synovial fluid, which can be predictors of disease onset and progression.Areas covered: This review provides an overview of the main biomarkers currently used in OA clinical practice, with a focus on lubricin, a surface glycoprotein secreted in the synovial fluid that lubricates the cartilage and reduces the coefficient of friction within the joint. Key findings of the last years are presented throughout the article.Expert opinion: Analysis of biomarkers might suggest personalized protocols of treatment, guide the classification of OA phenotypes, contribute to precision medicine, avoid further unnecessary exams, facilitate drug discovery or refine treatment guidelines. For all these reasons, the investigation of novel cartilage-based biomarker of osteoarthritis needs to be promoted and improved.

LINC00623/miR-101/HRAS axis modulates IL-1β-mediated ECM degradation, apoptosis and senescence of osteoarthritis chondrocytes

Chondrocyte apoptosis and extracellular matrix (ECM) degeneration have been implicated in the pathogenesis of osteoarthritis (OA). Based on previously reported microarray analysis, HRAS (Harvey rat sarcoma viral oncogene homolog), a member of the RAS protein family, was chosen as a potential regulator of OA chondrocyte apoptosis and ECM degradation. HRAS expression was downregulated in OA tissues, particularly in mild-OA tissues. HRAS overexpression partially attenuated IL-1β-induced OA chondrocyte apoptosis and ECM degradation. Similar to HRAS, the long non-coding RNA LINC00623 was downregulated in OA tissues. LINC00623 knockdown enhanced IL-1β-induced OA chondrocyte apoptosis and ECM degradation, which could be partially reversed by HRAS overexpression. It has been reported that lncRNAs act as ceRNAs of miRNAs to exert their function. Herein, miR-101 was predicted to bind to both LINC00623 and HRAS, which was further confirmed by luciferase reporter and RIP assays. LINC00623 competed with HRAS for miR-101 binding, therefore reducing the inhibitory effect of miR-101 on HRAS expression. More importantly, the effect of LINC00623 was partially eliminated by miR-101 inhibition. Overall, the LINC00623/miR-101/HRAS axis modulates OA chondrocyte apoptosis, senescence and ECM degradation through MAPK signaling, which might play a critical role in OA development.

MiR-375 Mediates Chondrocyte Metabolism and Oxidative Stress in Osteoarthritis Mouse Models through the JAK2/STAT3 Signaling Pathway

OBJECTIVE

The aim of this work was to determine the effect of miR-375 on chondrocyte metabolism and oxidative stress in osteoarthritis (OA) mouse models through the JAK2/STAT3 signaling pathway.

METHODS

Chondrocytes were divided into control, IL-1β, IL-1β + miR-375 mimic, IL-1β + miR-375 inhibitor, IL-1β + miR-NC (negative control), and IL-1β + miR-375 inhibitor + siJAK2 groups. The chondrocyte proliferation was determined by MTT assay, the superoxide dismutase (SOD) and malondialdehyde (MDA) levels by corresponding kits, and the chondrocyte apoptosis by TUNEL staining. Furthermore, OA mouse models were divided into Sham, OA + miR-NC, and OA + miRNA-375 antagomir groups. The pathological changes were observed, and the expressions of miR-375 and the JAK2/STAT3 pathway were determined by qRT-PCR and Western blotting, respectively.

RESULTS

IL-1β-induced chondrocytes had significant increases in miR-375 and MDA, with decreased proliferation and SOD levels, as compared to the control group. Meanwhile, they also exhibited elevated apoptosis, with upregulations of ADAMTS-5 and MMP-13 and downregulations of COL2A1 and ACAN, as well as decreased p-JAK2/JAK2, p-STAT3/STAT3, and Bcl-2/Bax. However, these changes were significantly improved after transfection with miR-375 inhibitor, but transfection with miR-375 mimic resulted in severer exacerbation. Notably, the improvement of miR-375 inhibitor could be abolished by transfection with siJAK2. Furthermore, miR-375 antagomir significantly alleviated OA progression in OA mice in vivo.

CONCLUSION

MiR-375 suppression enhanced the ability of chondrocyte to antagonize the oxidative stress and maintained the homeostasis of extracellular matrix metabolism to protect chondrocytes from OA via activation of the JAK2/STAT3 pathway, indicating that miR-375 is a potential molecular target for OA treatment.

Vitellaria paradoxa Nut Triterpene-Rich Extract Ameliorates Symptoms of Inflammation on Post-Traumatic Osteoarthritis in Obese Rats

Purpose

To investigate the ameliorative effects of Vitellaria paradoxa (VP) nut extract for an anterior cruciate ligament transection with medial meniscectomy (ACLT+MMx)-induced osteoarthritis (OA) in high-fat diet (HFD)-induced obese rats.

Methods

The rats were fed by HFD for 5 weeks before surgery-induced OA. Rats were treated orally with three different doses of VP nut extract (111.6, 223.2, and 446.4 mg/kg) for 8 weeks.

Results

The VP nut triterpene-rich extract decreased the level of triglycerides and increased high-density lipoprotein-cholesterol. The level of nitric oxide, interleukin (IL)-1β, IL-6, and tumor necrosis factor-α decreased after treatment with VP nut triterpene-rich extract, especially in high-doses. The VP nut triterpene-rich extracts also alleviated swelling in the knee OA, weight-bearing difference, and suppressed cartilage degradation.

Conclusion

The Vitellaria paradoxa nut triterpene-rich extract suppressed proinflammatory mediators and attenuated the cartilage degradation and pain in osteoarthritis with an obesity rat model. As such, Vitellaria paradoxa nut triterpene-rich extract can be used as an alternative for osteoarthritis treatment.

Coll2-1 and Coll2-1NO2 as exemplars of collagen extracellular matrix turnover - biomarkers to facilitate the treatment of osteoarthritis?

Introduction: Osteoarthritis (OA) is the most common form of arthritis. However, there are no structure or disease-modifying OA drugs (DMOADs). Introducing personalized healthcare to patients and health-care practitioners is a high priority for the management of arthritic and musculoskeletal diseases. However, there are no biomarker tools that can be used for patient stratification, disease management, and drug development. Biomarkers are capable of diagnosing and prognosing some arthritic and musculoskeletal diseases. Cartilage-based biomarkers have the potential to be used in this context to guide the precision treatment of OA. Areas covered: The aim of this review is to focus on the pre-clinical and clinical utility of the Coll2-1 and Coll2-1NO2 biomarkers as unique cartilage-based biomarkers that can guide the development of new treatments for OA. This expert report will begin with a background to collagens and their important biomechanical roles in the musculoskeletal system, but particularly cartilage, before exploring the data and scientific evidence to support the utility of Coll2-1 and Coll2-1NO2 as unique biomarkers. Expert opinion: This review summarises the authors' expert view on the pre-clinical and clinical utility of the Coll2-1 and Coll2-1NO2 biomarkers and their potential for use as drug development tools.

Downregulated CHI3L1 alleviates skeletal muscle stem cell injury in a mouse model of sepsis

Sepsis is an acute systemic inflammatory response of the body to microbial infection and a life-threatening condition associated with multiple organ failure. Recent data suggest that sepsis survivors present with long-term myopathy due to the dysfunction of skeletal muscle stem cells and satellite cells. Accumulating studies have implicated chitinase-3-like-1 protein (CHI3L1) in a variety of infectious diseases, specifically sepsis. Therefore, the aim of the present study is to elucidate the potential mechanism by which CHI3L1 is involved in the injury of skeletal muscle stem cells in mouse models of sepsis. An in vitro cell model was developed by lipopolysaccharide (LPS) and in vivo mouse model of sepsis was induced by CRP-like protein (CLP). To elucidate the biological significance behind the silencing of CHI3L1, modeled skeletal muscle stem cells and mice were treated with siRNA against CHI3L1 or overexpressed CHI3L1. Highly expressed CHI3L1 was found in skeletal muscle tissues of mice with sepsis. Besides, siRNA-mediated silencing of CHI3L1 was revealed to increase Bcl-2 expression along with cell proliferation, while diminishing Bax expression, cell apopstosis as well as serum levels of TNF-α, IL-1β, INF-γ, IL-10, and IL-6. Taken conjointly, this present study provided evidence suggesting that downregulation of CHI3L1 has the potential to prevent the injury of skeletal muscle stem cells in mice with sepsis. Collectively, CHI3L1 may serve as a valuable therapeutic strategy in alleviating sepsis.

Roles of chitinase 3-like 1 in the development of cancer, neurodegenerative diseases, and inflammatory diseases

Chitinase 3-like 1 (CHI3L1) is a secreted glycoprotein that mediates inflammation, macrophage polarization, apoptosis, and carcinogenesis. The expression of CHI3L1 is strongly increased by various inflammatory and immunological conditions, including rheumatoid arthritis, multiple sclerosis, Alzheimer's disease, and several cancers. However, its physiological and pathophysiological roles in the development of cancer and neurodegenerative and inflammatory diseases remain unclear. Several studies have reported that CHI3L1 promotes cancer proliferation, inflammatory cytokine production, and microglial activation, and that multiple receptors, such as advanced glycation end product, syndecan-1/αVβ3, and IL-13Rα2, are involved. In addition, the pro-inflammatory action of CHI3L1 may be mediated via the protein kinase B and phosphoinositide-3 signaling pathways and responses to various pro-inflammatory cytokines, including tumor necrosis factor-α, interleukin-1β, interleukin-6, and interferon-γ. Therefore, CHI3L1 could contribute to a vast array of inflammatory diseases. In this article, we review recent findings regarding the roles of CHI3L1 and suggest therapeutic approaches targeting CHI3L1 in the development of cancers, neurodegenerative diseases, and inflammatory diseases.

Significantly dysregulated genes in osteoarthritic labrum cells identified through gene expression profiling

The aim of the present study was to explore the molecular basis and identify significant genetic alterations in acetabular labrum cells associated with osteoarthritis (OA). Gene expression data of osteoarthritic and normal human labrum cells were downloaded from a public database and reanalyzed. Significant differentially expressed genes (DEGs) were acquired by performing a thorough analysis of microarray data between the OA acetabular labrum cells and control cells. Key genes in OA labrum cells were revealed by a combination of weighted gene co-expression network analysis (WGCNA) and protein-protein interaction (PPI) analysis. Literature mining and drug screening were further performed for these key genes. In total, 141 DEGs between OA and normal labrum cells were identified. In addition, WGCNA and PPI analysis identified 23 DEGs as key genes in the OA labrum. All the key genes were significantly downregulated in OA labrum cells and were grouped into two different WGCNA-PPI common subnetworks. Kinase insert domain receptor (KDR), CD34, cadherin 5 (CDH5), Fms related tyrosine kinase 1 (FLT1) and asporin were hub nodes in the PPI network of DEGs. These key genes were significantly enriched in functional clusters of transforming growth factor, alkaline phosphatase, bone morphogenic protein and extracellular matrix. Drug screening analysis identified several drugs targeting the key genes, including arachidonic acid, yohimbic acid and mimosine. The results of the present study indicate that the changes of FLT1, KDR, CD34 and CDH5 in acetabular labrum cells may be involved in the pathogenesis of OA and could serve as biomarkers and therapeutic targets of OA. Additionally, arachidonic acid, yohimbic acid and mimosine may act as potential drugs for OA.

Synovial fluid proteome changes in ACL injury-induced posttraumatic osteoarthritis: Proteomics analysis of porcine knee synovial fluid

Surgical transection of the anterior cruciate ligament (ACL) in the porcine model leads to posttraumatic osteoarthritis if left untreated. However, a recently developed surgical treatment, bridge-enhanced ACL repair, prevents further cartilage damage. Since the synovial fluid bathes all the intrinsic structures of knee, we reasoned that a comparative analysis of synovial fluid protein contents could help to better understand the observed chondroprotective effects of the bridge-enhanced ACL repair. We hypothesized that post-surgical changes in the synovial fluid proteome would be different in the untreated and repaired knees, and those changes would correlate with the degree of cartilage damage. Thirty adolescent Yucatan mini-pigs underwent unilateral ACL transection and were randomly assigned to either no further treatment (ACLT, n = 14) or bridge-enhanced ACL repair (BEAR, n = 16). We used an isotopically labeled high resolution LC MS/MS-based proteomics approach to analyze the protein profile of synovial fluid at 6 and 12 months after ACL transection in untreated and repaired porcine knees. A linear mixed effect model was used to compare the normalized protein abundance levels between the groups at each time point. Bivariate linear regression analyses were used to assess the correlations between the macroscopic cartilage damage (total lesion area) and normalized abundance levels of each of the identified secreted proteins. There were no significant differences in cartilage lesion area or quantitative abundance levels of the secreted proteins between the ACLT and BEAR groups at 6 months. However, by 12 months, greater cartilage damage was seen in the ACLT group compared to the BEAR group (p = 0.005). This damage was accompanied by differences in the abundance levels of secreted proteins, with higher levels of Vitamin K-dependent protein C (p = 0.001), and lower levels of Apolipoprotein A4 (p = 0.021) and Cartilage intermediate layer protein 1 (p = 0.049) in the ACLT group compared to the BEAR group. There were also group differences in the secreted proteins that significantly changed in abundance between 6 and 12 months in ACLT and BEAR knees. Increased concentration of Ig lambda-1 chain C regions and decreased concentration of Hemopexin, Clusterin, Coagulation factor 12 and Cartilage intermediate layer protein 1 were associated with greater cartilage lesion area. In general, ACLT knees had higher concentrations of pro-inflammatory proteins and lower concentrations of anti-inflammatory proteins than BEAR group. In addition, the ACLT group had a lower and declining synovial concentrations of CILP, in contrast to a consistently high abundance of CILP in repaired knees. These differences suggest that the knees treated with bridge-enhanced ACL repair may be maintaining an environment that is more protective of the extracellular matrix, a function which is not seen in the ACLT knees.

Caffeic acid and ellagic acid ameliorate adjuvant-induced arthritis in rats via targeting inflammatory signals, chitinase-3-like protein-1 and angiogenesis

Rheumatoid arthritis (RA) is a chronic inflammatory arthropathy that principally attacks the joints. The present study aimed to explore the potential anti-arthritic effects of caffeic acid and ellagic acid in adjuvant-induced arthritis, compared to celecoxib. The current study also explored the underlying molecular mechanisms e.g., pro-inflammatory signals including chitinase-3-like protein-1 (CHI3L1); a glycoprotein that correlates with RA joint destruction besides angiogenesis, oxidative stres and apoptosis. Interestingly, caffeic and ellagic acids attenuated the severity of arthritis with comparable efficacy to celecoxib. Both agents effectively mitigated paw edema and inflammatory cell infiltration and protected the joint tissues against pannus formation along with cartilage and bone destruction. Notably, they also lowered the paw expression of NF-κB and the downstream effector CHI3L1 and its synthesis inducer IL-1β. They also lowered the levels of the tissue remodeling factor MMP-9 and the angiogenic signal VEGF in rat paws. Both agents also suppressed serum oxidative stress via diminishing lipid peroxides and nitric oxide together with augmentation of reduced glutathione in arthritic animals. Regarding apoptosis, they attenuated paw caspase-3 levels, favoring cell survival. Together, these favorable findings may advocate the use of caffeic and ellagic acids as adjunct modalities for the management of RA to mitigate joint damage.

Moderate Physical Activity as a Prevention Method for Knee Osteoarthritis and the Role of Synoviocytes as Biological Key

The purpose of this study was to investigate the influence of moderate physical activity (MPA) on the expression of osteoarthritis (OA)-related (IL-1β, IL-6, TNF-α, MMP-13) and anti-inflammatory and chondroprotective (IL-4, IL-10, lubricin) biomarkers in the synovium of an OA-induced rat model. A total of 32 rats were divided into four groups: Control rats (Group 1); rats performing MPA (Group 2); anterior cruciate ligament transection (ACLT)-rats with OA (Group 3); and, ACLT-rats performing MPA (Group 4). Analyses were performed using Hematoxylin & Eosin (H&E) staining, histomorphometry and immunohistochemistry. In Group 3, OA biomarkers were significantly increased, whereas, IL-4, IL-10, and lubricin were significantly lower than in the other experimental groups. We hypothesize that MPA might partake in rescuing type B synoviocyte dysfunction at the early stages of OA, delaying the progression of the disease.

The Synovium Theory: Can Exercise Prevent Knee Osteoarthritis? The Role of "Mechanokines", A Possible Biological Key

Osteoarthritis (OA) is a debilitating disease widespread in the world, having a negative impact on daily activities, especially in old age [...].

Chitinase-3-like Protein 1: A Progranulin Downstream Molecule and Potential Biomarker for Gaucher Disease

We recently reported that progranulin (PGRN) is a novel regulator of glucocerebrosidase and its deficiency associates with Gaucher Diseases (GD) (Jian et al., 2016a; Jian et al., 2018). To isolate the relevant downstream molecules, we performed a whole genome microarray and mass spectrometry analysis, which led to the isolation of Chitinase-3-like-1 (CHI3L1) as one of the up-regulated genes in PGRN null mice. Elevated levels of CHI3L1 were confirmed by immunoblotting and immunohistochemistry. In contrast, treatment with recombinant Pcgin, a derivative of PGRN, as well as imigluerase, significantly reduced the expressions of CHI3L1 in both PGRN null GD model and the fibroblasts from GD patients. Serum levels of CHIT1, a clinical biomarker for GD, were significantly higher in GD patients than healthy controls (51.16±2.824ng/ml vs 35.07±2.099ng/ml, p<0.001). Similar to CHIT1, serum CHI3L1 was also significantly increased in GD patients compared with healthy controls (1736±152.1pg/ml vs 684.7±68.20pg/ml, p<0.001). Whereas the PGRN level is significantly reduced in GD patients as compared to the healthy control (91.56±3.986ng/ml vs 150.6±4.501, p<0.001). Collectively, these results indicate that CHI3L1 may be a previously unrecognized biomarker for diagnosing GD and for evaluating the therapeutic effects of new GD drug(s).

Is there still room for novelty, in histochemical papers?

Histochemistry continues to be widely applied in biomedical research, being nowadays mostly addressed to detect and locate single molecules or molecular complexes inside cells and tissues, and to relate structural organization and function at the high resolution of the more advanced microscopical techniques. In the attempt to see whether histochemical novelties may be found in the recent literature, the articles published in the European Journal of Histochemistry in the period 2014-2016 have been reviewed. In the majority of the published papers, standardized methods have been preferred by scientists to make their results reliably comparable with the data in the literature, but several papers (approximately one fourth of the published articles) described novel histochemical methods and procedures. It is worth noting that there is a growing interest for minimally-invasive in vivo techniques (magnetic resonance imaging, autofluorescence spectroscopy), which may parallel conventional histochemical analyses to acquire evidence not only on the morphological features of living organs and tissues, but also on their functional, biophysical and molecular characteristics. Thanks to this unceasing methodological refinement, histochemistry will continue to provide innovative applications in the biomedical field.

New insights on chitinases immunologic activities

Mammalian chitinases and the related chilectins (ChiLs) belong to the GH18 family, which hydrolyse the glycosidic bond of chitin by a substrate-assisted mechanism. Chitin the fundamental component in the coating of numerous living species is the most abundant natural biopolymer. Mounting evidence suggest that the function of the majority of the mammalian chitinases is not exclusive to catalyze the hydrolysis of chitin producing pathogens, but include crucial role specific in the immunologic activities. The chitinases and chitinase-like proteins are expressed in response to different proinflammatory cues in various tissues by activated macrophages, neutrophils and in different monocyte-derived cell lines. The mechanism and molecular interaction of chitinases in relation to immune regulation embrace bacterial infection, inflammation, dismetabolic and degenerative disease. The aim of this review is to update the reader with regard to the role of chitinases proposed in the recent innate and adaptive immunity literature. The deep scrutiny of this family of enzymes could be a useful base for further studies addressed to the development of potential procedure directing these molecules as diagnostic and prognostic markers for numerous immune and inflammatory diseases.

Chitinase 3 Like-1: An Emerging Molecule Involved in Diabetes and Diabetic Complications

Chitinase 3 like-1 (CHI3L1) is a chitinase-like protein member of family 18 chitinases, expressed in innate immune cells and involved in endothelial dysfunction and tissue remodelling. Since CHI3L1 is highly expressed in a variety of inflammatory diseases of infectious and non-infectious aetiology, it is recognised as a non-invasive prognostic biomarker for inflammation. A variety of studies revealing the increase in CHI3L1 levels in obesity, insulin resistance and in pathological conditions, such as atherosclerosis, coronary artery disease, acute ischaemic stroke, nephropathy, diabetic retinopathy and osteolytic processes, have suggested that CHI3L1 may also play a critical role in the evolution and complication of diabetes mellitus (DM). In this review we highlight the impact of CHI3L1 expression in DM and its contribution to the complication of this disease.

Altered joint tribology in osteoarthritis: Reduced lubricin synthesis due to the inflammatory process. New horizons for therapeutic approaches

Osteoarthritis (OA) is the most common form of joint disease. This review aimed to consolidate the current evidence that implicates the inflammatory process in the attenuation of synovial lubrication and joint tissue homeostasis in OA. Moreover, with these findings, we propose some evidence for novel therapeutic strategies for preventing and/or treating this complex disorder. The studies reviewed support that inflammatory mediators participate in the onset and progression of OA after joint injury. The flow of pro-inflammatory cytokines following an acute injury seems to be directly associated with altered lubricating ability in the joint tissue. The latter is associated with reduced level of lubricin, one of the major joint lubricants. Future research should focus on the development of new therapies that attenuate the inflammatory process and restore lubricin synthesis and function. This approach could support joint tribology and synovial lubrication leading to improved joint function and pain relief.

Co-Expression and Co-Localization of Cartilage Glycoproteins CHI3L1 and Lubricin in Osteoarthritic Cartilage: Morphological, Immunohistochemical and Gene Expression Profiles

Osteoarthritis is the most common human arthritis characterized by degeneration of articular cartilage. Several studies reported that levels of human cartilage glycoprotein chitinase 3-like-1 (CHI3L1) are known as a potential marker for the activation of chondrocytes and the progression of Osteoarthritis (OA), whereas lubricin appears to be chondroprotective. The aim of this study was to investigate the co-expression and co-localization of CHI3L1 and lubricin in normal and osteoarthritic rat articular cartilage to correlate their modified expression to a specific grade of OA. Samples of normal and osteoarthritic rat articular cartilage were analyzed by the Kellgren–Lawrence OA severity scores, the Kraus’ modified Mankin score and the Histopathology Osteoarthritis Research Society International (OARSI) system for histomorphometric evaluations, and through CHI3L1 and lubricin gene expression, immunohistochemistry and double immuno-staining analysis. The immunoexpression and the mRNA levels of lubricin increased in normal cartilage and decreased in OA cartilage (normal vs. OA, p < 0.01). By contrast, the immunoexpression and the mRNA levels of CHI3L1 increased in OA cartilage and decreased in normal cartilage (normal vs. OA, p < 0.01). Our findings are consistent with reports suggesting that these two glycoproteins are functionally associated with the development of OA and in particular with grade 2/3 of OA, suggesting that in the future they could be helpful to stage the severity and progression of the disease.

Animal models of osteoarthritis: classification, update, and measurement of outcomes

Osteoarthritis (OA) is one of the most commonly occurring forms of arthritis in the world today. It is a debilitating chronic illness causing pain and immense discomfort to the affected individual. Significant research is currently ongoing to understand its pathophysiology and develop successful treatment regimens based on this knowledge. Animal models have played a key role in achieving this goal. Animal models currently used to study osteoarthritis can be classified based on the etiology under investigation, primary osteoarthritis, and post-traumatic osteoarthritis, to better clarify the relationship between these models and the pathogenesis of the disease. Non-invasive animal models have shown significant promise in understanding early osteoarthritic changes. Imaging modalities play a pivotal role in understanding the pathogenesis of OA and the correlation with pain. These imaging studies would also allow in vivo surveillance of the disease as a function of time in the animal model. This review summarizes the current understanding of the disease pathogenesis, invasive and non-invasive animal models, imaging modalities, and pain assessment techniques in the animals.