TGF-β dampens IL-6 signaling in articular chondrocytes by decreasing IL-6 receptor expression

Chondrocyte Response to Fresh Autologous Conditioned Serum Versus Freeze-Dried Allogenic Conditioned Serum

OBJECTIVE

To investigate the cytokine release profile and histological response of human cartilage after exposure to autologous conditioned serum (ACS) and freeze-dried allogenic conditioned serum (FD-CS).

DESIGN

Cartilage explants were collected from 6 patients undergoing total knee arthroplasty. ACS and FD-CS were created from patient serum samples. Cartilage samples were divided into 6 groups: (1) untreated control, (2) ACS, (3) FD-CS, (4) untreated interleukin (IL)-1β (5 ng/ml), (5) IL-1β + ACS, and (6) IL-1β + FD-CS. After 12 days, cartilage samples were analyzed with glycosaminoglycan (GAG) concentration normalized to wet weight while comparing cytokine concentrations, and histological scoring.

RESULTS

There was a significant decrease in pathology scoring for ACS (P = 0.0368) and FD-CS (P = 0.0368) in the IL-1β injury groups compared with the untreated IL-1β insult group. ACS and FD-CS significantly mitigate the IL-1β induced increase in basic fibroblast growth factor (bFGF) (P = 0.0009 and P = 0.0002, respectively). FD-CS showed a significant decrease in IL-1β concentration in the presence of IL-1β insult compared with the untreated IL-1β group (P < 0.0001). ACS-treated samples had significantly higher concentration of tumor necrosis factor (TNF)-α independent of IL-1β when compared with samples not treated with biologics (P = 0.0053).

CONCLUSIONS

Explanted osteoarthritic cartilage responds favorably and equivalently to treatment with ACS and FD-CS from a histological perspective. Both ACS and FD-CS were able to mitigate the IL-1β-induced increases in bFGF and FD-CS lowered IL-1β concentration while increasing interleukin-1 receptor antagonist (IL-1Ra) concentration. Although the cytokine profile of cartilage tissue explants treated with FD-CS appears to be different than that of ACS, this difference does not seem to affect biologic activity of FD-CS.

Ursolic acid inhibits NF-κB signaling and attenuates MMP-9/TIMP-1 in progressive osteoarthritis: a network pharmacology-based analysis

Osteoarthritis (OA) is a degenerative joint disease, characterized by infiltration of monocytes into the synovial joint which promotes inflammation, stiffness, joint swelling, cartilage degradation and further bone destruction. The leaves of Ocimum forskolei have been used for inflammation-related disease management in traditional medicine. Additionally, the downregulation of NF-κB and the MMP/TIMP-1 ratio has been shown to protect against OA. The LC-HR-MS metabolic analysis of Ocimum yielded 19 putative compounds, among which ursolic acid (UA) was detected. Ursolic acid possesses significant anti-inflammatory effects and has been reported to downregulate oxidative stress and inflammatory biomarkers. It was tested on rats in a model of intra-articular carrageenan injection to investigate its efficacy on osteoarthritis progression. The UA emulgel exerted chondroprotective, analgesic and local anaesthetic efficacies confirmed via histopathological investigation and radiographical imaging. A network pharmacology followed by molecular docking highlighted TNF-α, TGF-β and NF-κB as the top filtered genes. Quantitative real-time PCR analysis showed that UA significantly attenuated serum levels of TNF-α, IL-1β, NF-κB, MMP-9/TIMP-1 and elevated levels of TGF-β. Taken together, these results suggest that UA could serve as a functional food-derived phytochemical with a multi-targeted efficacy on progression of OA, regulating the immune and inflammatory responses, particularly, attenuating chondrocytes degeneration via suppression of NF-κB and MMP-9/TIMP-1. Accordingly, UA might be a promising alternative to conventional therapy for safe, easily applicable and effective management of OA.

Emerging technology has a brilliant future: the CRISPR-Cas system for senescence, inflammation, and cartilage repair in osteoarthritis

Osteoarthritis (OA), known as one of the most common types of aseptic inflammation of the musculoskeletal system, is characterized by chronic pain and whole-joint lesions. With cellular and molecular changes including senescence, inflammatory alterations, and subsequent cartilage defects, OA eventually leads to a series of adverse outcomes such as pain and disability. CRISPR-Cas-related technology has been proposed and explored as a gene therapy, offering potential gene-editing tools that are in the spotlight. Considering the genetic and multigene regulatory mechanisms of OA, we systematically review current studies on CRISPR-Cas technology for improving OA in terms of senescence, inflammation, and cartilage damage and summarize various strategies for delivering CRISPR products, hoping to provide a new perspective for the treatment of OA by taking advantage of CRISPR technology.

Importance of IL-6 trans-signaling and high autocrine IL-6 production in human osteoarthritic chondrocyte metabolism

OBJECTIVE

Neutralization of Interleukin (IL)-6-signaling by antibodies is considered a promising tool for the treatment of osteoarthritis (OA). To gain further insight into this potential treatment, this study investigated the effects of IL-6-signaling and IL-6 neutralization on chondrocyte metabolism and the release of IL-6-signaling-related mediators by human chondrocytes.

DESIGN

Chondrocytes were collected from 49 patients with advanced knee/hip OA or femoral neck fracture. Isolated chondrocytes were stimulated with different mediators to analyze the release of IL-6, soluble IL-6 receptor (sIL-6R) and soluble gp130 (sgp130). The effect of IL-6 and IL-6/sIL-6R complex as well as neutralization of IL-6-signaling on the metabolism was analyzed.

RESULTS

OA chondrocytes showed high basal IL-6 production and release, which was strongly negatively correlated with the production of cartilage-matrix-proteins. Chondrocytes produced and released sIL-6R and sgp130. The IL-6/sIL-6R complex significantly increased nitric oxide, prostaglandin E2 and matrix metalloproteinase 1 production, decreased Pro-Collagen Type II and mitochondrial ATP production, and increased glycolysis in OA chondrocytes. Neutralization of IL-6-signaling by antibodies did not significantly affect the metabolism of OA chondrocytes, but blocking of glycoprotein 130 (gp130)-signaling by SC144 significantly reduced the basal IL-6 release.

CONCLUSION

Although IL-6 trans-signaling induced by IL-6/sIL-6R complex negatively affects OA chondrocytes, antibodies against IL-6 or IL-6R did not affect chondrocyte metabolism. Since inhibition of gp130-signaling reduced the enhanced basal release of IL-6, interfering with gp130-signaling may ameliorate OA progression because high cellular release of IL-6 correlates with reduced production of cartilage-matrix-proteins.

Inflammation in osteoarthritis: Our view on its presence and involvement in disease development over the years

Inflammation, both locally in the joint and systemic, is nowadays considered among the mechanisms involved in osteoarthritis (OA). However, this concept has not always been generally accepted. In fact, for long OA has been described as a relatively simple degeneration of articular cartilage as the result of wear and tear only. In this narrative review, we present what our understanding of OA was at the time of the inaugural release of Osteoarthritis and Cartilage about 30 years ago and discuss a set of pivotal papers that changed our view on the role of inflammation in OA development. Furthermore, we briefly discuss the current view on the involvement of inflammation in OA. Next, we use the example of transforming growth factor-β signaling to show how inflammation might influence processes in the joint in a manner that is beyond the simple interaction of ligand and receptor leading to the release of inflammatory and catabolic mediators. Finally, we discuss our view on what should be done in the future to bring the field forward.

Deciphering the developmental trajectory of tissue-resident Foxp3+ regulatory T cells

Foxp3+ TREG cells have been at the focus of intense investigation for their recognized roles in preventing autoimmunity, facilitating tissue recuperation following injury, and orchestrating a tolerance to innocuous non-self-antigens. To perform these critical tasks, TREG cells undergo deep epigenetic, transcriptional, and post-transcriptional changes that allow them to adapt to conditions found in tissues both at steady-state and during inflammation. The path leading TREG cells to express these tissue-specialized phenotypes begins during thymic development, and is further driven by epigenetic and transcriptional modifications following TCR engagement and polarizing signals in the periphery. However, this process is highly regulated and requires TREG cells to adopt strategies to avoid losing their regulatory program altogether. Here, we review the origins of tissue-resident TREG cells, from their thymic and peripheral development to the transcriptional regulators involved in their tissue residency program. In addition, we discuss the distinct signalling pathways that engage the inflammatory adaptation of tissue-resident TREG cells, and how they relate to their ability to recognize tissue and pathogen-derived danger signals.

Pharmacological and immunomodulatory modes of action of medically important phytochemicals against arthritis: A molecular insight

Arthritis is a common illness that affects joints and it may result in inflammation and pain. Even though arthritis usually affects older people, it can also affect children, adults, and both genders. Numerous arthritic mouse models have been developed but the CIA model of rheumatoid arthritis (RA) has received the most attention. With the use of steroids, DMARDs, and NSAIDs, therapy objectives such as reduced disease incidence and better pain management are achieved. Long-term usage of these therapeutic approaches may have negative side effects. Herbal medications are the source of several medicinal substances. Studies have explored the potential benefits of medicinal plants in treating RA. These benefits include up-regulating antioxidant potential, inhibiting cartilage degradation, down-regulating inflammatory cytokines such as NF-kB, IL-6, and TNF-α, and suppressing oxidative stress. In this review, we systematically discuss the role of traditional medicinal plants in rheumatoid arthritis (RA) disease treatment. The role of different medicinal plants such as Curcuma longa, Syzygium aromaticum, Zingiber officinale and Withania somnifera, against arthritis is discussed in this review.

The roles and regulatory mechanisms of TGF-β and BMP signaling in bone and cartilage development, homeostasis and disease

Transforming growth factor-βs (TGF-βs) and bone morphometric proteins (BMPs) belong to the TGF-β superfamily and perform essential functions during osteoblast and chondrocyte lineage commitment and differentiation, skeletal development, and homeostasis. TGF-βs and BMPs transduce signals through SMAD-dependent and -independent pathways; specifically, they recruit different receptor heterotetramers and R-Smad complexes, resulting in unique biological readouts. BMPs promote osteogenesis, osteoclastogenesis, and chondrogenesis at all differentiation stages, while TGF-βs play different roles in a stage-dependent manner. BMPs and TGF-β have opposite functions in articular cartilage homeostasis. Moreover, TGF-β has a specific role in maintaining the osteocyte network. The precise activation of BMP and TGF-β signaling requires regulatory machinery at multiple levels, including latency control in the matrix, extracellular antagonists, ubiquitination and phosphorylation in the cytoplasm, nucleus-cytoplasm transportation, and transcriptional co-regulation in the nuclei. This review weaves the background information with the latest advances in the signaling facilitated by TGF-βs and BMPs, and the advanced understanding of their diverse physiological functions and regulations. This review also summarizes the human diseases and mouse models associated with disordered TGF-β and BMP signaling. A more precise understanding of the BMP and TGF-β signaling could facilitate the development of bona fide clinical applications in treating bone and cartilage disorders.

Effects of Premixing Betamethasone and Lidocaine on Chondrocyte Inflammation in an In Vitro Model

BACKGROUND

It is common practice for hand surgeons to premix corticosteroids with a local anesthetic and store the mixture in pre-loaded syringes for rapid use during clinic. However, any possible loss of efficacy with this practice has never been studied. The purpose of this study, therefore, is to determine whether premixing betamethasone sodium phosphate/betamethasone acetate (BSP) and lidocaine (L) at different time intervals from injection has diminishing anti-inflammatory effects on chondrocytes in vitro.

METHODS

Human articular chondrocytes were partitioned into six groups: two controls and four experimental conditions. The negative control had growth media only. The positive control had growth media and inflammatory cytokines (interleukin-1β and oncostatin M). Experimental conditions were additionally treated with BSP alone or BSP mixed with lidocaine (BSP + L) at the time of treatment (0 hours), or at 4 or 24 hours prior. Relative expressions of inflammatory genes were measured.

RESULTS

Relative to the positive control, chondrocytes in all experimental conditions decreased expression of TNF-α, MMP-3, and ADAMTS-4. Chondrocytes exposed to BSP only or BSP + L at 4 hours or 24 hours prior to treatment decreased expression of IL-8. Chondrocytes exposed to BSP only or BSP + L at 0 hours or 4 hours prior to treatment decreased expression of MMP-1. There were no significant differences in expression of IL-6 or MMP-13.

CONCLUSIONS

Treatment with BSP + L prepared in pre-loaded syringes at varying time intervals up to 24 hours prior to injection does not significantly impact the ability of the mixture to reduce expression of certain key inflammatory mediators in vitro.

Adipose Tissue-Derived Products May Present Inflammatory Properties That Affect Chondrocytes and Synoviocytes from Patients with Knee Osteoarthritis

Adipose tissue-derived cell-based injectable therapies have been demonstrated to have disease-modifying effects on joint tissues in preclinical studies on animal osteoarthritis (OA) models, but clinical results are heterogeneous and not always satisfactory. The aim of this study was to investigate the influence of adipose tissue properties on the therapeutic effects of the adipose-derived product in an in vitro OA setting. Micro-fragmented adipose tissue (MF-AT) samples were obtained from 21 OA patients (mean age 51.7 ± 11.8 years, mean BMI 25.7 ± 4.1 kg/m2). The analysis of the MF-AT supernatant was performed to analyze the release of inflammatory factors. The effects of MF-AT inflammatory factors were investigated on chondrocytes and synoviocytes gene expression levels. Patients' characteristics were analyzed to explore their influence on MF-AT inflammatory molecules and on the MF-AT effects on the gene expression of chondrocytes and synoviocytes. The study results demonstrated that adipose tissue-derived products may present inflammatory properties that influence the therapeutic potential for OA treatment, with products with a higher pro-inflammatory profile stimulating a higher expression of genes related to a more inflamed and catabolic phenotype. A higher pro-inflammatory cytokine pattern and a higher pro-inflammatory effect were found in adipose tissue-derived products obtained from OA patients with higher BMI.

Unravelling the Basic Calcium Phosphate crystal-dependent chondrocyte protein secretome; a role for TGF-β signaling

OBJECTIVE

Basic Calcium Phosphate (BCP) crystals play an active role in the progression of osteoarthritis (OA). However, the cellular consequences remain largely unknown. Therefore, we characterized for the first time the changes in the protein secretome of human OA articular chondrocytes as a result of BCP stimulation using two unbiased proteomic analysis methods.

METHOD

Isolated human OA articular chondrocytes were stimulated with BCP crystals and examined by Quantitative Reverse Transcription PCR (RT-qPCR) and enzyme-linked immune sorbent assay (ELISA) after twenty-four and forty-eight hours. Forty-eight hours conditioned media were analyzed by label-free liquid chromatography-tandem mass spectrometry (LC-MS/MS) and an antibody array. The activity of BCP dependent Transforming Growth Factor Beta (TGF-β) signaling was analyzed by RT-qPCR and luciferase reporter assays. The molecular consequences regarding BCP-dependent TGF-β signaling on BCP-dependent Interleukin 6 (IL-6) were investigated using specific pathway inhibitors.

RESULTS

Synthesized BCP crystals induced IL-6 expression and secretion upon stimulation of human articular chondrocytes. Concomitant induction of catabolic gene expression was observed. Analysis of conditioned media revealed a complex and diverse response with a large number of proteins involved in TGF-β signaling, both in activation of latent TGF-β and TGF-β superfamily members, which were increased compared to non-stimulated OA chondrocytes. Activity of this BCP driven TGF-β signaling was confirmed by increased activity of expression of TGF-β target genes and luciferase reporters. Inhibition of BCP driven TGF-β signaling resulted in decreased IL-6 expression and secretion with a moderate effect on catabolic gene expression.

CONCLUSION

BCP crystal stimulation resulted in a complex and diverse chondrocyte protein secretome response. An important role for BCP-dependent TGF-β signaling was identified in development of a pro-inflammatory environment.

Innate and Adaptive Immunity-Related Markers as Predictors of the Short-Term Progression of Subclinical Atherosclerosis in Middle-Aged Patients

Assessment of inflammation is a promising approach to monitoring the progression of asymptomatic atherosclerosis. The aim of the present study was to investigate the predictive value of innate and adaptive immunity-related markers, in relation to the short-term progression of subclinical atherosclerosis. The study included 183 patients aged 40-64 years who underwent duplex scanning of the carotid and lower limb arteries at two visits with an interval of 12-24 months between examinations. Phenotyping of circulating lymphocytes and monocytes subpopulations were performed through flow cytometry. An increase in the number of circulating TLR4-positive intermediate monocytes (>447.0-467.0 cells/μL) was an independent predictor of the short-term progression of lower limb artery atherosclerosis (p < 0.0001) and polyvascular atherosclerosis (p = 0.003). The assessment of TLR4-positive monocytes significantly improved the prognostic model for the progression of lower limb arterial atherosclerosis (C-index 0.728 (0.642-0.815) versus 0.637 (0.539-0.735); p = 0.038). An increase in the number of circulating TLR4-positive intermediate monocytes was an independent predictor of the short-term progression of lower limb artery and polyvascular atherosclerosis. Their inclusion into models containing conventional risk factors significantly improved their prognostic effectiveness regarding lower limb artery atherosclerosis progression.

The Role of Genetics and Epigenetic Regulation in the Pathogenesis of Osteoarthritis

Osteoarthritis (OA) is progressive disease characterised by cartilage degradation, subchondral bone remodelling and inflammation of the synovium. The disease is associated with obesity, mechanical load and age. However, multiple pro-inflammatory immune mediators regulate the expression of metalloproteinases, which take part in cartilage degradation. Furthermore, genetic factors also contribute to OA susceptibility. Recent studies have highlighted that epigenetic mechanisms may regulate the expression of OA-associated genes. This review aims to present the mechanisms of OA pathogenesis and summarise current evidence regarding the role of genetics and epigenetics in this process.

The mechanism of action of safflower total flavonoids in the treatment of endometritis caused by incomplete abortion based on network pharmacology and 16S rDNA sequencing

ETHNOPHARMACOLOGICAL RELEVANCE

Safflower is a traditional Chinese medicine used for treating gynaecological diseases. However, its material basis and mechanism of action in the treatment of endometritis induced by incomplete abortion are still unclear.

AIM OF THE STUDY

This study aimed to reveal the material basis and mechanism of action of safflower in the treatment of endometritis induced by incomplete abortion through comprehensive methods, including network pharmacology and 16S rDNA sequencing.

MATERIALS AND METHODS

Network pharmacology and molecular docking methods were used to screen the main active components and potential mechanisms of action of safflower in the treatment of endometritis induced by incomplete abortion in rats. A rat model of endometrial inflammation by incomplete abortion was established. The rats were treated with safflower total flavonoids (STF) based on forecasting results, serum levels of inflammatory cytokines were analysed, and immunohistochemistry, Western blots, and 16S rDNA sequencing were performed to investigate the effects of the active ingredient and the treatment mechanism.

RESULTS

The network pharmacology prediction results showed 20 active components with 260 targets in safflower, 1007 targets related to endometritis caused by incomplete abortion, and 114 drug-disease intersecting targets, including TNF, IL6, TP53, AKT1, JUN, VEGFA, CASP3 and other core targets, PI3K/AKT, MAPK and other signalling pathways may be closely related to incomplete abortion leading to endometritis. The animal experiment results showed that STF could significantly repair uterine damage and reduce the amount of bleeding. Compared with the model group, STF significantly down-regulated the levels of pro-inflammatory factors (IL-6, IL-1β, NO, TNF-α) and the expression of JNK, ASK1, Bax, caspase3, and caspase11 proteins. At the same time, the levels of anti-inflammatory factors (TGF-β and PGE2) and the protein expression of ERα, PI3K, AKT, and Bcl2 were up-regulated. Significant differences in the intestinal flora were seen between the normal group and the model group, and the intestinal flora of the rats was closer to the normal group after the administration of STF.

CONCLUSIONS

The characteristics of STF used in the treatment of endometritis induced by incomplete abortion were multi-targeted and involved multiple pathways. The mechanism may be related to the activation of the ERα/PI3K/AKT signalling pathway by regulating the composition and ratio of the gut microbiota.

Lipid-Independent Regulation of PLIN5 via IL-6 through the JAK/STAT3 Axis in Hep3B Cells

Perilipin 5 (PLIN5) is a lipid droplet coat protein that is highly expressed in oxidative tissues such as those of muscles, the heart and the liver. PLIN5 expression is regulated by a family of peroxisome proliferator-activated receptors (PPARs) and modulated by the cellular lipid status. So far, research has focused on the role of PLIN5 in the context of non-alcoholic fatty liver disease (NAFLD) and specifically in lipid droplet formation and lipolysis, where PLIN5 serves as a regulator of lipid metabolism. In addition, there are only limited studies connecting PLIN5 to hepatocellular carcinoma (HCC), where PLIN5 expression is proven to be upregulated in hepatic tissue. Considering that HCC development is highly driven by cytokines present throughout NAFLD development and in the tumor microenvironment, we here explore the possible regulation of PLIN5 by cytokines known to be involved in HCC and NAFLD progression. We demonstrate that PLIN5 expression is strongly induced by interleukin-6 (IL-6) in a dose- and time-dependent manner in Hep3B cells. Moreover, IL-6-dependent PLIN5 upregulation is mediated by the JAK/STAT3 signaling pathway, which can be blocked by transforming growth factor-β (TGF-β) and tumor necrosis factor-α (TNF-α). Furthermore, IL-6-mediated PLIN5 upregulation changes when IL-6 trans-signaling is stimulated through the addition of soluble IL-6R. In sum, this study sheds light on lipid-independent regulation of PLIN5 expression in the liver, making PLIN5 a crucial target for NAFLD-induced HCC.

Cartilage extracellular matrix-derived matrikines in osteoarthritis

Osteoarthritis (OA) is among the most frequent diseases of the musculoskeletal system. Degradation of cartilage extracellular matrix (ECM) is a hallmark of OA. During the degradation process, intact/full-length proteins and proteolytic fragments are released which then might induce different downstream responses via diverse receptors, therefore leading to different biological consequences. Collagen type II and the proteoglycan aggrecan are the most abundant components of the cartilage ECM. However, over the last decades, a large number of minor components have been identified and for some of those, a role in the manifold processes associated with OA has already been demonstrated. To date, there is still no therapy able to halt or cure OA. A better understanding of the matrikine landscape occurring with or even preceding obvious degenerative changes in joint tissues is needed and might help to identify molecules that could serve as biomarkers, druggable targets, or even be blueprints for disease modifying drug OA drugs. For this narrative review, we screened PubMed for relevant literature in the English language and summarized the current knowledge regarding the function of selected ECM molecules and the derived matrikines in the context of cartilage and OA.

Protective effects of Tripterygium glycoside on IL-1β-induced inflammation and apoptosis of rat chondrocytes via microRNA-216a-5p/TLR4/NF-κB axis

BACKGROUND

This study is designed to fill the research gap concerning the efficacy of Tripterygium glycoside (TG) on Interleukin-1β (IL-1β)-induced inflammation and injury in chondrocytes.

METHODS

Chondrocytes were isolated from Sprague-Dawley rats. After the treatment with IL-1β and TG and transfection, the viability and apoptosis of chondrocytes were determined via Cell Counting Kit-8 (CCK-8) assay and flow cytometry. The levels of inflammatory cytokines tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and IL-8 were determined by enzyme-linked immunosorbent assay (ELISA). Relative expression levels of potential microRNAs (miRNAs, miRs) that may target toll-like receptor 4 (TLR4), as well as apoptosis- and TLR4/nuclear factor-κB (TLR4/NF-κB) pathway-associated factors were quantified using quantitative real-time (qRT) PCR and western blot. The targeting relationship between miR-216a-5p and TLR4 was predicted by TargetScan and further confirmed by dual-luciferase reporter assay.

RESULTS

The viability was reduced yet the apoptosis and inflammation were promoted in IL-1β-treated chondrocytes, where upregulation of Bax, Cleaved caspase 3, TLR4, Myeloid differentiation factor 88 (MyD88), phosphorylation of P65 and IκBα yet downregulation of Bcl-2 and IκBα were evidenced. Strikingly, the above changes were reversed by TG. TG also offset the effects of IL-1β on repressing the expression of miR-216a-5p, the miRNA targeting TLR4. Additionally, TLR4 overexpression neutralized the impacts of TG upon viability, apoptosis, and TLR4 expression in IL-1β-treated chondrocytes, while all these effects induced by TLR4 overexpression could be restored by miR-216a-5p.

CONCLUSIONS

TG protects chondrocytes against IL-1β-induced inflammation and apoptosis via miR-216a-5p/TLR4/NF-κB axis.

Loss of alcohol dehydrogenase 1B in cancer-associated fibroblasts: contribution to the increase of tumor-promoting IL-6 in colon cancer

BACKGROUND

Increases in IL-6 by cancer-associated fibroblasts (CAFs) contribute to colon cancer progression, but the mechanisms involved in the increase of this tumor-promoting cytokine are unknown. The aim of this study was to identify novel targets involved in the dysregulation of IL-6 expression by CAFs in colon cancer.

METHODS

Colonic normal (N), hyperplastic, tubular adenoma, adenocarcinoma tissues, and tissue-derived myo-/fibroblasts (MFs) were used in these studies.

RESULTS

Transcriptomic analysis demonstrated a striking decrease in alcohol dehydrogenase 1B (ADH1B) expression, a gene potentially involved in IL-6 dysregulation in CAFs. ADH1B expression was downregulated in approximately 50% of studied tubular adenomas and all T1-4 colon tumors, but not in hyperplastic polyps. ADH1B metabolizes alcohols, including retinol (RO), and is involved in the generation of all-trans retinoic acid (atRA). LPS-induced IL-6 production was inhibited by either RO or its byproduct atRA in N-MFs, but only atRA was effective in CAFs. Silencing ADH1B in N-MFs significantly upregulated LPS-induced IL-6 similar to those observed in CAFs and lead to the loss of RO inhibitory effect on inducible IL-6 expression.

CONCLUSION

Our data identify ADH1B as a novel potential mesenchymal tumor suppressor, which plays a critical role in ADH1B/retinoid-mediated regulation of tumor-promoting IL-6.

Targeting caveolae to pump bispecific antibody to TGF-β into diseased lungs enables ultra-low dose therapeutic efficacy

The long-sought-after "magic bullet" in systemic therapy remains unrealized for disease targets existing inside most tissues, theoretically because vascular endothelium impedes passive tissue entry and full target engagement. We engineered the first "dual precision" bispecific antibody with one arm pair to precisely bind to lung endothelium and drive active delivery and the other to precisely block TGF-β effector function inside lung tissue. Targeting caveolae for transendothelial pumping proved essential for delivering most of the injected intravenous dose precisely into lungs within one hour and for enhancing therapeutic potency by >1000-fold in a rat pneumonitis model. Ultra-low doses (μg/kg) inhibited inflammatory cell infiltration, edema, lung tissue damage, disease biomarker expression and TGF-β signaling. The prodigious benefit of active vs passive transvascular delivery of a precision therapeutic unveils a new promising drug design, delivery and therapy paradigm ripe for expansion and clinical testing.

Genetic Factors for Coronary Heart Disease and Their Mechanisms: A Meta-Analysis and Comprehensive Review of Common Variants from Genome-Wide Association Studies

Genome-wide association studies (GWAS) have discovered 163 loci related to coronary heart disease (CHD). Most GWAS have emphasized pathways related to single-nucleotide polymorphisms (SNPs) that reached genome-wide significance in their reports, while identification of CHD pathways based on the combination of all published GWAS involving various ethnicities has yet to be performed. We conducted a systematic search for articles with comprehensive GWAS data in the GWAS Catalog and PubMed, followed by a meta-analysis of the top recurring SNPs from ≥2 different articles using random or fixed-effect models according to Cochran Q and I² statistics, and pathway enrichment analysis. Meta-analyses showed significance for 265 of 309 recurring SNPs. Enrichment analysis returned 107 significant pathways, including lipoprotein and lipid metabolisms (rs7412, rs6511720, rs11591147, rs1412444, rs11172113, rs11057830, rs4299376), atherogenesis (rs7500448, rs6504218, rs3918226, rs7623687), shared cardiovascular pathways (rs72689147, rs1800449, rs7568458), diabetes-related pathways (rs200787930, rs12146487, rs6129767), hepatitis C virus infection/hepatocellular carcinoma (rs73045269/rs8108632, rs56062135, rs188378669, rs4845625, rs11838776), and miR-29b-3p pathways (rs116843064, rs11617955, rs146092501, rs11838776, rs73045269/rs8108632). In this meta-analysis, the identification of various genetic factors and their associated pathways associated with CHD denotes the complexity of the disease. This provides an opportunity for the future development of novel CHD genetic risk scores relevant to personalized and precision medicine.

The Wnt signaling cascade in the pathogenesis of osteoarthritis and related promising treatment strategies

Osteoarthritis (OA) is the most prevalent joint disease, characterized by the degradation of articular cartilage, synovial inflammation, and changes in periarticular and subchondral bone. Recent studies have reported that Wnt signaling cascades play an important role in the development, growth, and homeostasis of joints. The Wnt signaling cascade should be tightly regulated to maintain the homeostasis of cartilage in either the over-activation or the suppression of Wnt/β-catenin, as this could lead to OA. This review summarizes the role and mechanism of canonical Wnt cascade and noncanonical Wnt cascade experiments in vivo and in vitro. The Wnt cascade is controlled by several agonists and antagonists in the extracellular medium and the cytoplasm. These antagonists and agonists serve as key molecules in drug intervention into the Wnt pathway and may provide potential approaches for the treatment of OA. However, the complexity of the Wnt signaling cascade and the pharmaceutical effects on its mechanism are still not fully understood, which forces us to conduct further research and develop efficient therapeutic approaches to treat OA.

Paradoxical Duel Role of Collagen in Rheumatoid Arthritis: Cause of Inflammation and Treatment

In biology, collagen-biomaterial regulates several signaling mechanisms of bone and immune cells involved in tissue repair and any imbalance in collagen turnover may affect the homeostasis of cells, becoming a major cause of several complications. In this case, the administration of oral collagen may play a potential role in returning cells to their normal function. For several decades, the beneficial effects of collagen have been explored widely, and thus many commercial products are available in cosmetics, food, and biomedical fields. For instance, collagen-based-products have been widely used to treat the complications of cartilage-related-disorders. Many researchers are reporting the anti-arthritogenic properties of collagen-based materials. In contrast, collagen, especially type-II collagen (CII), has been widely used to induce arthritis by immunization in an animal-model with or without adjuvants, and the potentially immunogenic-properties of collagen have been continuously reported for a long time. Additionally, the immune tolerance of collagen is mainly regulated by the T-lymphocytes and B-cells. This controversial hypothesis is getting more and more evidence nowadays from both sides to support its mechanism. Therefore, this review links the gap between the arthritogenic and anti-arthritogenic effects of collagen and explored the actual mechanism to understand the fundamental concept of collagen in arthritis. Accordingly, this review opens-up several unrevealed scientific knots of collagen and arthritis and helps the researchers understand the potential use of collagen in therapeutic applications.

Tofacitinib May Inhibit Myofibroblast Differentiation from Rheumatoid-Fibroblast-like Synoviocytes Induced by TGF-β and IL-6

During rheumatoid arthritis (RA), the pathogenic role of resident cells within the synovial membrane is suggested, especially for a population frequently referred to as fibroblast-like synoviocytes (FLSs). In this study, we assess the markers of myofibroblast differentiation of RA-FLSs by ex vivo observations and in vitro evaluations following the stimulation with both TGF-β and IL-6. Furthermore, we investigated the possible inhibiting role of tofacitinib, a JAK inhibitor, in this context. Myofibroblast differentiation markers were evaluated on RA synovial tissues by immune-fluorescence or immune-histochemistry. RA-FLSs, stimulated with transforming growth factor (TGF-β) and interleukin-6 (IL-6) with/without tofacitinib, were assessed for myofibroblast differentiation markers expression by qRT-PCR and Western blot. The same markers were evaluated following JAK-1 silencing by siRNA assay. The presence of myofibroblast differentiation markers in RA synovial tissue was significantly higher than healthy controls. Ex vivo, α-SMA was increased, whereas E-Cadherin decreased. In vitro, TGF-β and IL-6 stimulation of RA-FLSs promoted a significant increased mRNA expression of collagen I and α-SMA, whereas E-Cadherin mRNA expression was decreased. In the same conditions, the stimulation with tofacitinib significantly reduced the mRNA expression of collagen I and α-SMA, even if the Western blot did not confirm this finding. JAK-1 gene silencing did not fully prevent the effects of stimulation with TGF-β and IL-6 on these features. TGF-β and IL-6 stimulation may play a role in mediating myofibroblast differentiation from RA-FLSs, promoting collagen I and α-SMA while decreasing E-Cadherin. Following the same stimulation, tofacitinib reduced the increases of both collagen I and α-SMA on RA-FLSs, although further studies are needed to fully evaluate this issue and confirm our results.

Identification of Transcription Factors Responsible for a Transforming Growth Factor-β-Driven Hypertrophy-like Phenotype in Human Osteoarthritic Chondrocytes

During osteoarthritis (OA), hypertrophy-like chondrocytes contribute to the disease process. TGF-β's signaling pathways can contribute to a hypertrophy(-like) phenotype in chondrocytes, especially at high doses of TGF-β. In this study, we examine which transcription factors (TFs) are activated and involved in TGF-β-dependent induction of a hypertrophy-like phenotype in human OA chondrocytes. We found that TGF-β, at levels found in synovial fluid in OA patients, induces hypertrophic differentiation, as characterized by increased expression of RUNX2, COL10A1, COL1A1, VEGFA and IHH. Using luciferase-based TF activity assays, we observed that the expression of these hypertrophy genes positively correlated to SMAD3:4, STAT3 and AP1 activity. Blocking these TFs using specific inhibitors for ALK-5-induced SMAD signaling (5 µM SB-505124), JAK-STAT signaling (1 µM Tofacitinib) and JNK signaling (10 µM SP-600125) led to the striking observation that only SB-505124 repressed the expression of hypertrophy factors in TGF-β-stimulated chondrocytes. Therefore, we conclude that ALK5 kinase activity is essential for TGF-β-induced expression of crucial hypertrophy factors in chondrocytes.

Local inhibition of TGF-β1 signaling improves Th17/Treg balance but not joint pathology during experimental arthritis

TGF-β1 is an important growth factor to promote the differentiation of T helper 17 (Th17) and regulatory T cells (Treg). The potential of TGF-β1 as therapeutic target in T cell-mediated diseases like rheumatoid arthritis (RA) is unclear. We investigated the effect of TGF-β1 inhibition on murine Th17 differentiation in vitro, on human RA synovial explants ex vivo, and on the development of experimental arthritis in vivo. Murine splenocytes were differentiated into Th17 cells, and the effect of the TGF-βRI inhibitor SB-505124 was studied. Synovial biopsies were cultured in the presence or absence of SB-505124. Experimental arthritis was induced in C57Bl6 mice and treated daily with SB-505124. Flow cytometry analysis was performed to measure different T cell subsets. Histological sections were analysed to determine joint inflammation and destruction. SB-505124 potently reduced murine Th17 differentiation by decreasing Il17a and Rorc gene expression and IL-17 protein production. SB-505124 significantly suppressed IL-6 production by synovial explants. In vivo, SB-505124 reduced Th17 numbers, while increased numbers of Tregs were observed. Despite this skewed Th17/Treg balance, SB-505124 treatment did not result in suppression of joint inflammation and destruction. Blocking TGF-β1 signalling suppresses Th17 differentiation and improves the Th17/Treg balance. However, local SB-505124 treatment does not suppress experimental arthritis.

Interleukin-6 Induced Proliferation Is Attenuated by Transforming Growth Factor-β-Induced Signaling in Human Hepatocellular Carcinoma Cells

Hepatocellular carcinoma (HCC) is often associated with an inflammatory setting. A plethora of cytokines are secreted in this milieu, actively contributing to the progression of the disease; however, the extent of cytokine interaction and how it contributes to HCC development remains an enigma. In this regard, our analysis of available patient-derived data suggests that cytokines like interleukin-6 (IL-6) and transforming growth factor-beta (TGF-β) are enriched in HCC. We further analyzed the effect of these cytokines independently or in combination on HCC cells. Importantly, IL-6 was found to induce a STAT-3-dependent proliferation and mediate its pro-proliferative effects through activation and direct interaction with the p65 subunit of NFkB. Alternatively, TGF-β was found to induce a SMAD-dependent induction of epithelial to mesenchymal transition (EMT) coupled to growth arrest in these cells. Interestingly, the simultaneous addition of IL-6 and TGF-β failed to profoundly impact EMT markers but resulted in attenuation of IL-6-induced pro-proliferative effects. Analysis of the putative molecular mechanism revealed a decrease in IL-6 receptor (IL-6R) transcript levels, reduced expression of IL-6-induced STAT-3, and its nuclear localization upon addition of TGF-β along with IL-6. Consequently, a reduced p65 activation was also observed in combination treatment. Importantly, SMAD levels were unperturbed and the cells showed more TGF-β-like features under combination treatment. Finally, we observed that TGF-β resulted in enrichment of repressive chromatin mark (H3K27me3) coupled to growth arrest, while IL-6 induced an open chromatin signature (H3K4me3) associated with an enhanced expression of EZH2. Overall, for the first time, we show that TGF-β attenuates IL-6-induced effects by regulating the receptor level, downstream signaling, and the epigenome. Understanding the complex interactions between these cytokines can be imperative to a better understanding of the disease, and manipulation of cytokine balance can act as a prospective future therapeutic strategy.

Restoration of the Phenotype of Dedifferentiated Rabbit Chondrocytes by Sesquiterpene Farnesol

Osteoarthritis (OA) is a joint disorder characterized by the progressive degeneration of articular cartilage. The phenotype and metabolism behavior of chondrocytes plays crucial roles in maintaining articular cartilage function. Chondrocytes dedifferentiate and lose their cartilage phenotype after successive subcultures or inflammation and synthesize collagen I and X (COL I and COL X). Farnesol, a sesquiterpene compound, has an anti-inflammatory effect and promotes collagen synthesis. However, its potent restoration effects on differentiated chondrocytes have seldom been evaluated. The presented study investigated farnesol's effect on phenotype restoration by examining collagen and glycosaminoglycan (GAG) synthesis from dedifferentiated chondrocytes. The results indicated that chondrocytes gradually dedifferentiated through cellular morphology change, reduced expressions of COL II and SOX9, increased the expression of COL X and diminished GAG synthesis during four passages of subcultures. Pure farnesol and hyaluronan-encapsulated farnesol nanoparticles promote COL II synthesis. GAG synthesis significantly increased 2.5-fold after a farnesol treatment of dedifferentiated chondrocytes, indicating the restoration of chondrocyte functions. In addition, farnesol drastically increased the synthesis of COL II (2.5-fold) and GAG (15-fold) on interleukin-1β-induced dedifferentiated chondrocytes. A significant reduction of COL I, COL X and proinflammatory cytokine prostaglandin E2 was observed. In summary, farnesol may serve as a therapeutic agent in OA treatment.

The potential roles of JAK/STAT signaling in the progression of osteoarthritis

Osteoarthritis (OA) is an age-related chronic progressive degenerative disease that induces persistent pain and disabilities. The development of OA is a complex process, and the risk factors are various, including aging, genetics, trauma and altered biomechanics. Inflammation and immunity play an important role in the pathogenesis of OA. JAK/STAT pathway is one of the most prominent intracellular signaling pathways, regulating cell proliferation, differentiation, and apoptosis. Inflammatory factors can act as the initiators of JAK/STAT pathway, which is implicated in the pathophysiological activity of chondrocyte. In this article, we provide a review on the importance of JAK/STAT pathway in the pathological development of OA. Potentially, JAK/STAT pathway becomes a therapeutic target for managing OA.

Increase in Free and Total Plasma TGF-β1 Following Physical Activity

OBJECTIVE

To evaluate effects of physical activity and food consumption on plasma concentrations of free and total transforming growth factor beta-1 (TGF-β1), beta-2 (TGF-β2), and beta-3 (TGF-β3) in individuals with knee osteoarthritis (OA).

METHODS

Participants (n = 40 in 2 cohorts of 20; mean age 70 years) with radiographic knee OA were admitted overnight for serial blood sampling. Cohorts 1 and 2 assessed the impacts of food intake and activity, respectively, on TGF-β concentrations. Cohort 1 blood draws included 2 hours postprandial the evening of day 1 (T3), fasting before rising on day 2 (T0), nonfasting 1 hour after rising (T1B), and 4 hours after rising (T2). Cohort 2 blood draws included T3, T0, fasting 1 hour after rising and performing activities of daily living (T1A), and nonfasting 2 hours after rising (T1B). By sandwich ELISAs, we quantified plasma free and total TGF-β1 concentrations in all samples, and plasma total TGF-β2 and TGF-β3 in cohort 2.

RESULTS

Free TGF-β1 represented a small fraction of the total systemic concentration (mean 0.026%). In cohort 2, free and total TGF-β1 and total TGF-β2 concentration significantly increased in fasting samples collected after an hour (T1A) of activities of daily living (free TGF-β1: P = 0.006; total TGF-β1: P < 0.001; total TGF-β2: P = 0.001). Total TGF-β3 increased nonsignificantly following activity (P = 0.590) and decreased (P = 0.035) after food consumption while resting (T1B).

CONCLUSIONS

Increased plasma concentrations of TGF-β with physical activity suggests activity should be standardized prior to TGF-β1 analyses.

Role of microRNA Shuttled in Small Extracellular Vesicles Derived From Mesenchymal Stem/Stromal Cells for Osteoarticular Disease Treatment

Osteoarticular diseases (OD), such as rheumatoid arthritis (RA) and osteoarthritis (OA) are chronic autoimmune/inflammatory and age-related diseases that affect the joints and other organs for which the current therapies are not effective. Cell therapy using mesenchymal stem/stromal cells (MSCs) is an alternative treatment due to their immunomodulatory and tissue differentiation capacity. Several experimental studies in numerous diseases have demonstrated the MSCs’ therapeutic effects. However, MSCs have shown heterogeneity, instability of stemness and differentiation capacities, limited homing ability, and various adverse responses such as abnormal differentiation and tumor formation. Recently, acellular therapy based on MSC secreted factors has raised the attention of several studies. It has been shown that molecules embedded in extracellular vesicles (EVs) derived from MSCs, particularly those from the small fraction enriched in exosomes (sEVs), effectively mimic their impact in target cells. The biological effects of sEVs critically depend on their cargo, where sEVs-embedded microRNAs (miRNAs) are particularly relevant due to their crucial role in gene expression regulation. Therefore, in this review, we will focus on the effect of sEVs derived from MSCs and their miRNA cargo on target cells associated with the pathology of RA and OA and their potential therapeutic impact.

High Induction of IL-6 Secretion From hUCMSCs Optimize the Potential of hUCMSCs and TCZ as Therapy for COVID-19-Related ARDS

Biological and cellular interleukin-6 (IL-6)-related therapies have been used to treat severe COVID-19 pneumonia with hyperinflammatory syndrome and acute respiratory failure, which prompted further exploration of the role of IL-6 in human umbilical cord mesenchymal stem cell (hUCMSC) therapy. Peripheral blood mononuclear cells (PBMCs) were responders cocultured with hUCMSCs or exogenous IL-6. A PBMC suppression assay was used to analyze the anti-inflammatory effects via MTT assay. The IL-6 concentration in the supernatant was measured using ELISA. The correlation between the anti-inflammatory effect of hUCMSCs and IL-6 levels and the relevant roles of IL-6 and IL-6 mRNA expression was analyzed using the MetaCore functional network constructed from gene microarray data. The location of IL-6 and IL-6 receptor (IL-6R) expression was further evaluated. We reported that hUCMSCs did not initially exert any inhibitory effect on PHA-stimulated proliferation; however, a potent inhibitory effect on PHA-stimulated proliferation was observed, and the IL-6 concentration reached approximately 1000 ng/mL after 72 hours. Exogenous 1000 ng/mL IL-6 inhibited PHA-stimulated inflammation but less so than hUCMSCs. The inhibitory effects of hUCMSCs on PHA-stimulated PBMCs disappeared after adding an IL-6 neutralizing antibody or pretreatment with tocilizumab (TCZ), an IL-6R antagonist. hUCMSCs exert excellent anti-inflammatory effects by inducing higher IL-6 levels, which is different from TCZ. High concentration of IL-6 cytokine secretion plays an important role in the anti-inflammatory effect of hUCMSC therapy. Initial hUCMSC therapy, followed by TCZ, seems to optimize the therapeutic potential to treat COVID-19-related acute respiratory distress syndrome (ARDS).

Crosstalk between immune cells and bone cells or chondrocytes

The term "osteoimmunology" was coined to denote the bridge between the immune system and the skeletal system. Osteoimmunology is interdisciplinary, and a full understanding and development of this "bridge" will provide an in-depth understanding of the switch between body health and disease development. B lymphocytes can promote the maturation and differentiation of osteoclasts, and osteoclasts have a negative feedback effect on B lymphocytes. Different subtypes of T lymphocytes regulate osteoclasts in different directions. T lymphocytes have a two-way regulatory effect on osteoblasts, while B lymphocytes have minimal regulatory effects on osteoblasts. In contrast, osteoblasts can promote the differentiation and maturation of T lymphocytes and B lymphocytes. Different immune cells have different effects on chondrocytes; some cooperate with each other, while some antagonize each other. In a healthy adult body, bone resorption and bone formation are in a dynamic balance under the action of multiple mechanisms. In this review, we summarize the interactions and key signaling molecular mechanisms between each type of cell in the immune system and the skeletal system.

Inhibition of nuclear receptor RORα attenuates cartilage damage in osteoarthritis by modulating IL-6/STAT3 pathway

Osteoarthritis (OA) is characterized by cartilage destruction, chronic inflammation, and local pain. Evidence showed that retinoic acid receptor-related orphan receptor-α (RORα) is crucial in cartilage development and OA pathogenesis. Here, we investigated the role and molecular mechanism of RORα, an important member of the nuclear receptor family, in regulating the development of OA pathologic features. Investigation into clinical cartilage specimens showed that RORα expression level is positively correlated with the severity of OA and cartilage damage. In an in vivo OA model induced by anterior crucial ligament transaction, intra-articular injection of si-Rora adenovirus reversed the cartilage damage. The expression of cartilage matrix components type II collagen and aggrecan were elevated upon RORα blockade. RNA-seq data suggested that the IL-6/STAT3 pathway is significantly downregulated, manifesting the reduced expression level of both IL-6 and phosphorylated STAT3. RORα exerted its effect on IL-6/STAT3 signaling in two different ways, including interaction with STAT3 and IL-6 promoter. Taken together, our findings indicated the pivotal role of the RORα/IL-6/STAT3 axis in OA progression and confirmed that RORα blockade improved the matrix catabolism in OA chondrocytes. These results may provide a potential treatment target in OA therapy.

Signaling Pathways Involved in Diabetic Renal Fibrosis

Diabetic kidney disease (DKD), as the most common complication of diabetes mellitus (DM), is the major cause of end-stage renal disease (ESRD). Renal interstitial fibrosis is a crucial metabolic change in the late stage of DKD, which is always considered to be complex and irreversible. In this review, we discuss the pathological mechanisms of diabetic renal fibrosis and discussed some signaling pathways that are closely related to it, such as the TGF-β, MAPK, Wnt/β-catenin, PI3K/Akt, JAK/STAT, and Notch pathways. The cross-talks among these pathways were then discussed to elucidate the complicated cascade behind the tubulointerstitial fibrosis. Finally, we summarized the new drugs with potential therapeutic effects on renal fibrosis and listed related clinical trials. The purpose of this review is to elucidate the mechanisms and related pathways of renal fibrosis in DKD and to provide novel therapeutic intervention insights for clinical research to delay the progression of renal fibrosis.

Increased IL-6 receptor expression and signaling in ageing cartilage can be explained by loss of TGF-β-mediated IL-6 receptor suppression

OBJECTIVE

Osteoarthritis (OA) development is strongly associated with ageing, possibly due to age-related changes in transforming growth factor-β (TGF-β) signaling in cartilage. Recently, we showed that TGF-β suppresses interleukin (IL)-6 receptor (IL-6R) expression in chondrocytes. As IL-6 is involved in cartilage degeneration, we hypothesized that age-related loss of TGF-β signaling results in increased IL-6R expression and signaling in ageing cartilage.

DESIGN

Bovine articular cartilage was collected and immediately processed to study age-related changes in IL-6R expression using qPCR and IHC (age-range: 0.5-14 years). Moreover, cartilage from young and aged cows was stimulated with rhIL-6 and/or rhTGF-β1 to measure IL-6-induced p-STAT3 using Western blot. Expression of STAT3-responsive genes was analyzed using qPCR.

RESULTS

Expression of IL-6 receptor (bIL-6R) significantly increased in cartilage upon ageing (slope: 0.32, 95%CI: 0.20-0.45), while expression of glycoprotein 130 (bGP130) was unaffected. Cartilage stimulation with IL-6 showed increased induction of p-STAT3 upon ageing (slope: 0.14, 95%CI: 0.08-0.20). Furthermore, IL-6-mediated induction of STAT3-responsive genes like bSOCS3 and bMMP3 was increased in aged compared to young cartilage. Interestingly, the ability of TGF-β to suppress bIL6R expression in young cartilage was lost upon ageing (slope: 0.21, 95%CI: 0.13-0.30). Concurrently, an age-related loss in TGF-β-mediated suppression of IL-6-induced p-STAT3 and bSOCS3 expression was observed.

CONCLUSIONS

Ageing results in enhanced IL-6R expression and subsequent IL-6-induced p-STAT3 signaling in articular cartilage. This is likely caused by age-related loss of protective TGF-β signaling, resulting in loss of TGF-β-mediated IL-6R suppression. Because of the detrimental role of IL-6 in cartilage, this mechanism may be involved in age-related OA development.

Lower androgen levels promote abnormal cartilage development in female patients with adolescent idiopathic scoliosis

Background

Adolescent idiopathic scoliosis (AIS) is a disease characterized by changes in the three-dimensional structure of the spine. Studies have shown that the development of AIS might be associated with genetic, biomechanics, endocrine factors and abnormal bone or cartilage development.

Methods

Blood samples collected from 301 female patients (161 females with AIS and 140 females without AIS) were used for genotyping. Forty-eight serum samples from 161 females with AIS and 40 serum samples from 140 females without AIS were subjected to enzyme-linked immunosorbent assays (ELISAs). We also evaluated 32 facet joints (18 females with AIS and 14 females without AIS from the 301 female patients) using immunohistochemistry, Western blotting, and isolation of human primary chondrocytes, among other methods. We treated the AIS primary chondrocytes with dihydrotestosterone (DHT) to verify the relationship among androgen, the androgen receptor (AR), and its downstream pathway proteins.

Results

The serum androgen level in the AIS group was significantly decreased (1.94±0.09 vs. 2.284±0.103) compared with that in the non-AIS (control) group. The single nucleotide polymorphism genotyping results showed that the mutation rates of rs6259 between the AIS and control groups were significantly different (G/G genotype: 48.4% vs. 42.1%, G/A genotype: 40.4% vs. 35.7%, P<0.05). The levels of interleukin (IL)-6 and metalloproteinase (MMP)-13 were increased in the cartilage of AIS patients, and these patients also exhibited decreased AR levels. The cell experiment results showed that androgen reduced the degree of abnormal cartilage development in female AIS patients through the AR/IL-6/signal transducer and activator of transcription 3 (STAT3) signaling pathway.

Conclusions

Our study provides a new perspective on the pathogenesis of AIS and indicates that decreased androgen levels in female AIS patients play a potential role in the development of AIS via the AR/IL-6/STAT3 signaling pathway.

A roadmap to target interleukin-6 in osteoarthritis

Joint inflammation is present in the majority of OA patients and pro-inflammatory mediators, such as IL-6, are actively involved in disease progression. Increased levels of IL-6 in serum or synovial fluid from OA patients correlate with disease incidence and severity, with IL-6 playing a pivotal role in the development of cartilage pathology, e.g. via induction of matrix-degrading enzymes. However, IL-6 also increases expression of anti-catabolic factors, suggesting a protective role. Until now, this dual role of IL-6 is incompletely understood and may be caused by differential effects of IL-6 classic vs trans-signalling. Here, we review current evidence regarding the role of IL-6 classic- and trans-signalling in local joint pathology of cartilage, synovium and bone. Furthermore, we discuss targeting of IL-6 in experimental OA models and provide future perspective for OA treatment by evaluating currently available IL-6 targeting strategies.

Gene Expression Signatures of Synovial Fluid Multipotent Stromal Cells in Advanced Knee Osteoarthritis and Following Knee Joint Distraction

Osteoarthritis (OA) is the most common musculoskeletal disorder. Although joint replacement remains the standard of care for knee OA patients, knee joint distraction (KJD), which works by temporarily off-loading the joint for 6–8 weeks, is becoming a novel joint-sparing alternative for younger OA sufferers. The biological mechanisms behind KJD structural improvements remain poorly understood but likely involve joint-resident regenerative cells including multipotent stromal cells (MSCs). In this study, we hypothesized that KJD leads to beneficial cartilage-anabolic and anti-catabolic changes in joint-resident MSCs and investigated gene expression profiles of synovial fluid (SF) MSCs following KJD as compared with baseline. To obtain further insights into the effects of local biomechanics on MSCs present in late OA joints, SF MSC gene expression was studied in a separate OA arthroplasty cohort and compared with subchondral bone (SB) MSCs from medial (more loaded) and lateral (less loaded) femoral condyles from the same joints. In OA arthroplasty cohort (n = 12 patients), SF MSCs expressed lower levels of ossification- and hypotrophy-related genes [bone sialoprotein (IBSP), parathyroid hormone 1 receptor (PTH1R), and runt-related transcription factor 2 (RUNX2)] than did SB MSCs. Interestingly, SF MSCs expressed 5- to 50-fold higher levels of transcripts for classical extracellular matrix turnover molecules matrix metalloproteinase 1 (MMP1), a disintegrin and metalloproteinase with thrombospondin motifs 5 (ADAMTS5), and tissue inhibitor of metalloproteinase-3 (TIMP3), all (p < 0.05) potentially indicating greater cartilage remodeling ability of OA SF MSCs, compared with SB MSCs. In KJD cohort (n = 9 patients), joint off-loading resulted in sustained, significant increase in SF MSC colonies’ sizes and densities and a notable transcript upregulation of key cartilage core protein aggrecan (ACAN) (weeks 3 and 6), as well as reduction in pro-inflammatory C–C motif chemokine ligand 2 (CCL2) expression (weeks 3 and 6). Additionally, early KJD changes (week 3) were marked by significant increases in MSC chondrogenic commitment markers gremlin 1 (GREM1) and growth differentiation factor 5 (GDF5). In combination, our results reveal distinct transcriptomes on joint-resident MSCs from different biomechanical environments and show that 6-week joint off-loading leads to transcriptional changes in SF MSCs that may be beneficial for cartilage regeneration. Biomechanical factors should be certainly considered in the development of novel MSC-based therapies for OA.

Resveratrol alleviates the interleukin-1β-induced chondrocytes injury through the NF-κB signaling pathway

BACKGROUND

Osteoarthritis (OA) is a regular age-related disease that affects millions of people. Resveratrol (RSV) is a flavonoid with a stilbene structure with different pharmacological effects. The purpose of the experiment was to evaluate the protective role of RSV against the human OA chondrocyte injury induced by interleukin-1β (IL-1β).

METHODS

Chondrocytes were isolated from OA patients and identified by type II collagen, safranin O staining, and toluidine blue staining. Differentially expressed genes in chondrocytes treated RSV were identified by RNA sequencing. Kyoto encyclopedia of genes and genomes (KEGG) pathway as well as gene ontology (GO) were further conducted through Metascape online tool. A cell counting kit-8 (CCK-8) assay was applied to discover the viability of chondrocytes (6, 12, 24, and 48 μM). Many genes associated with inflammation and matrix degradation are evaluated by real-time PCR (RT-PCR) as well as western blot (WB). The mechanism of RSV for protecting IL-1β induced chondrocytes injury was further measured through immunofluorescence and WB assays.

RESULTS

A total of 845 differentially expressed genes (upregulated = 499, downregulated = 346) were found. These differentially expressed genes mainly enriched into negative regulation of catabolic process, autophagy, and cellular catabolic process, intrinsic apoptotic, apoptotic, and regulation of apoptotic signaling pathway, cellular response to abiotic stimulus, external stimuli, stress, and radiation. These differentially expressed genes were obviously enriched in NF-kB signaling pathway. RSV at the concentration of 48 μM markedly weakened the viability of the cells after 24 h of treatment (87% vs 100%, P < 0.05). No obvious difference was observed between the 6, 12, and 24 μM groups (106% vs 100%, 104% vs 100%, 103% vs 100%, P > 0.05). RSV (24 μM) also markedly depressed the levels of PGE2 and NO induced by IL-1β by 25% and 29% respectively (P < 0.05). Our experiment pointed out that RSV could dramatically inhibit the inflammatory response induced by IL-1β, including the MMP-13, MMP-3, and MMP-1 in human OA chondrocytes by 50%, 35%, and 33% respectively. On the other hand, RSV inhibited cyclooxygenase-2 (COX-2), matrix metalloproteinase-1 (MMP-1), MMP-3, MMP-13, and inducible nitric oxide synthase (iNOs) expression (P < 0.05), while increased collagen-II and aggrecan levels (P < 0.05). From a mechanistic perspective, RSV inhibited the degradation of IκB-α as well as the activation of nuclear factor-kappa B (NF-κB) induced by IL-1β.

CONCLUSION

In summary, RSV regulates the signaling pathway of NF-κB, thus inhibiting inflammation and matrix degradation in chondrocytes. More studies should be focused on the treatment efficacy of RSV for OA in vivo.

Kartogenin mediates cartilage regeneration by stimulating the IL-6/Stat3-dependent proliferation of cartilage stem/progenitor cells

A decrease in the number of endogenous stem cells in cartilage is regarded as the cause of cartilage degeneration. Kartogenin (KGN) is known to induce chondrogenesis of cartilage stem/progenitor cells (CSPCs). Using CSPCs isolated from rat cartilage, we analysed changes in the transcriptome after treatment with KGN in vitro. An animal model of destabilization of the medial meniscus (DMM) was then used to identify the effect of intra-articular (IA) KGN injection on CSPC proliferation in vivo. Here, we demonstrated that KGN promoted the proliferation of CSPCs isolated from cartilage. The percentage of G2-M phase cells in the KGN-treated group reached over 10%, nearly twice that in the control group. Transcriptomic profiling of rat CSPCs revealed significant changes in KGN-treated samples compared to control samples. The gene expression levels of IL-6 and its coreceptor Gp130 were much higher in the KGN-treated group than in the control group. Phosphorylation of the IL-6 downstream molecule Stat3 was enhanced via KGN stimulation. The DMM animal model showed increased articular cartilage thickness after IA KGN injection. IHC staining also demonstrated upregulation of Stat3 phosphorylation and enhanced distribution of CD44⁺/CD105⁺ cells in cartilage following IA KGN injection. Thus, our data suggested that KGN promoted cartilage regeneration at least partially by stimulating IL-6/Stat3-dependent proliferation.

Excessive Production of Transforming Growth Factor β1 Causes Mural Cell Depletion From Cerebral Small Vessels

It is increasingly becoming apparent that cerebrovascular dysfunction contributes to the pathogenic processes involved in vascular dementia, Alzheimer’s disease, and other neurodegenerative disorders. Under these pathologic conditions, the degeneration of cerebral blood vessels is frequently accompanied by a loss of mural cells from the vascular walls. Vascular mural cells play pivotal roles in cerebrovascular functions, such as regulation of cerebral blood flow and maintenance of the blood-brain barrier (BBB). Therefore, cerebrovascular mural cell impairment is involved in the pathophysiology of vascular-related encephalopathies, and protecting these cells is essential for maintaining brain health. However, our understanding of the molecular mechanism underlying mural cell abnormalities is incomplete. Several reports have indicated that dysregulated transforming growth factor β (TGFβ) signaling is involved in the development of cerebral arteriopathies. These studies have specifically suggested the involvement of TGFβ overproduction. Although cerebrovascular toxicity via vascular fibrosis by extracellular matrix accumulation or amyloid deposition is known to occur with enhanced TGFβ production, whether increased TGFβ results in the degeneration of vascular mural cells in vivo remains unknown. Here, we demonstrated that chronic TGFβ1 overproduction causes a dropout of mural cells and reduces their coverage on cerebral vessels in both smooth muscle cells and pericytes. Mural cell degeneration was also accompanied by vascular luminal dilation. TGFβ1 overproduction in astrocytes significantly increased TGFβ1 content in the cerebrospinal fluid (CSF) and increased TGFβ signaling-regulated gene expression in both pial arteries and brain capillaries. These results indicate that TGFβ is an important effector that mediates mural cell abnormalities under pathological conditions related to cerebral arteriopathies.

TGFβ/BMP Signaling Pathway in Cartilage Homeostasis

Cartilage homeostasis is governed by articular chondrocytes via their ability to modulate extracellular matrix production and degradation. In turn, chondrocyte activity is regulated by growth factors such as those of the transforming growth factor β (TGFβ) family. Members of this family include the TGFβs, bone morphogenetic proteins (BMPs), and growth and differentiation factors (GDFs). Signaling by this protein family uniquely activates SMAD-dependent signaling and transcription but also activates SMAD-independent signaling via MAPKs such as ERK and TAK1. This review will address the pivotal role of the TGFβ family in cartilage biology by listing several TGFβ family members and describing their signaling and importance for cartilage maintenance. In addition, it is discussed how (pathological) processes such as aging, mechanical stress, and inflammation contribute to altered TGFβ family signaling, leading to disturbed cartilage metabolism and disease.