Adaptor proteins and Ras synergistically regulate IL-1-induced ADAMTS-4 expression in human chondrocytes

Identification of Andrographolide as a novel FABP4 inhibitor for osteoarthritis treatment

BACKGROUND AND PURPOSE

Fatty acid binding protein 4 (FABP4) has been identified as a contributor to cartilage degradation in osteoarthritis (OA) patients, and inhibiting FABP4 using small molecules has emerged as a promising approach for developing OA drugs. Our previous research showed that Andrographis paniculata, a medicinal plant, strongly inhibits FABP4 activity. This led us to hypothesize that Andrographis paniculata ingredients might have protective effects on OA cartilage through FABP4 inhibition.

METHODS

We analyzed scRNA-seq data from joint tissue of OA patients (GSE152805; GSE145286) using Scanpy 1.9.1 and Single Cell Portal. We conducted docking analysis of FABP4 inhibitors using Autodock Vina v.1.0.2. We evaluated the anti-FABP4 activity using a fluorescence displacement assay and measured the fatty acid oxidation (FAO) activity using the FAOBlue assay. We used H₂DCF-DA to measure reactive oxygen species (ROS) levels. We studied signaling pathways using bulk RNA sequencing and western blot analysis in human C28/I2 chondrocytes. We evaluated anti-OA activity in monosodium iodoacetate (MIA)-induced rats.

RESULTS

We identified Andrographolide (AP) as a novel FABP4 inhibitor. Bulk RNA-sequencing analysis revealed that FABP4 upregulated FAO and ROS in chondrocytes, which was inhibited by AP. ROS generation activated the NF-κB pathway, leading to overexpression of a disintegrin and metalloproteinase with thrombospondin motifs 4 (ADAMTS4), which is a responsible factor for cartilage degradation in OA patients. AP inhibited FABP4, thereby reducing the overexpression of ADAMTS4 by inhibiting the NF-κB pathway. In MIA rats, AP treatment reduced the overexpression of ADAMTS4, repaired cartilage and subchondral bone, and promoted cartilage regeneration.

CONCLUSION

Our results indicate that the inhibition of FABP4 activity by AP explains the anti-OA properties of Andrographis paniculata by protecting against cartilage degradation in OA patients. Additionally, our findings suggest that AP may be a promising therapeutic agent for OA treatment due to its ability to alleviate cartilage damage and bone erosion.

Synergistic upregulation of ADAMTS4 (aggrecanase-1) by cytokines and its suppression in knee osteoarthritic synovial fibroblasts

The ADAMTS (a disintegrin and metalloproteinase with thrombospondin motifs) family includes nine members with aggrecan-degrading activity, i.e., ADAMTS1, 4, 5, 8, 9, 15, 16, 18, and 20. However, their systematic expression profile in knee osteoarthritis (OA) synovium and effects of cytokines and growth factors on the expression in OA synovial fibroblasts remain elusive. In this study, expression of all nine aggrecanolytic ADAMTS species was assessed by quantitative real-time PCR in OA and control normal synovial tissues. OA synovial fibroblasts were treated with interleukin-1α (IL-1α), IL-1β, tumor necrosis factor-α (TNF-α), transforming growth factor-β (TGF-β), vascular endothelial growth factor165, and heparin-binding epidermal growth factor, and analyzed for the expression of the ADAMTS species. The signaling pathways and inhibition of ADAMTS4 expression by high-molecular-weight hyaluronan, adalimumab, tocilizumab, and signaling molecule inhibitors were studied. ADAMTS1, 4, 5, 9, and 16 were expressed in OA synovium, but only ADAMTS4 expression was significantly higher in OA as compared to normal synovium. IL-1α, TNF-α, and TGF-β markedly increased ADAMTS4 expression, while their effects were minimal for the other ADAMTS species. ADAMTS4 was synergistically upregulated by treatment with IL-1α and TNF-α, IL-1α and TGF-β, or IL-1α, TNF-α and TGF-β. The signaling molecules' inhibitors demonstrated that IL-1α-induced ADAMTS4 expression is predominantly through TGF-β-associated kinase 1 (TAK1), and the TNF-α-stimulated expression is via TAK1 and nuclear factor-κB (NF-κB). The TGF-β-promoted expression was through the activin receptor-like kinase 5 (ALK5)/Smad2/3, TAK1, and non-TAK1 pathways. Adalimumab blocked TNF-α-stimulated expression. ADAMTS4 expression co-stimulated with IL-1α, TNF-α and TGF-β was abolished by treatment with adalimumab, TAK1 inhibitor, and ALK5/Smad2/3 inhibitor. These data demonstrate marked and synergistic upregulation of ADAMTS4 by IL-1α, TNF-α and TGF-β in OA synovial fibroblasts, and suggest that concurrent therapy with an anti-TNF-α drug and inhibitor(s) may be useful for prevention against aggrecan degradation in OA.

NADPH oxidases in bone and cartilage homeostasis and disease: A promising therapeutic target

Reactive oxygen species (ROS) generated by the NADPH oxidase (Nox) enzymes are important short-range signaling molecules. They have been extensively studied in the physiology and pathophysiology of the cardiovascular system, where they have important roles in vascular inflammation, angiogenesis, hypertension, cardiac injury, stroke, and aging. Increasing evidence demonstrates that ROS and Nox enzymes also affect bone homeostasis and osteoporosis, and more recent studies implicate ROS and Nox enzymes in both inflammatory arthritis and osteoarthritis. Mechanistically, this connection may be through the effects of ROS on signal transduction. ROS affect both transforming growth factor-β/Smad signaling, interleukin-1β/nuclear factor-kappa B signaling, and the resulting changes in matrix metalloproteinase expression. The purpose of this review is to describe the role of Nox enzymes in the physiology and pathobiology of bone and joints and to highlight the potential of therapeutically targeting the Nox enzymes.

Ibuprofen attenuates interleukin-1β-induced inflammation and actin reorganization via modulation of RhoA signaling in rabbit chondrocytes

Ibuprofen, a medication in the nonsteroidal anti-inflammatory drug class, is widely used for treating inflammatory diseases such as osteoarthritis. It has been shown in recent years that ibuprofen has a strong effect on Ras homolog gene family, member A (RhoA) inhibition in multiple cell types. Our previous finding also demonstrated that interleukin-1β (IL-1β) increases filamentous actin (F-actin) of chondrocytes via RhoA pathway. Therefore, we hypothesized that ibuprofen may suppress the IL-1β-induced F-actin upregulation in chondrocytes by inhibiting RhoA pathway. To this end, in this study, articular chondrocytes from New Zealand White rabbits were pretreated with 500 μM ibuprofen for 2 h, then with 10 ng/ml IL-1β for 24 h. Results showed that pretreatment with ibuprofen inhibited the IL-1β-induced nitric oxide (NO) and prostaglandin E2 (PGE2) production, protected the chondrocyte phenotype from IL-1β stimulation, and inhibited the IL-1β-induced actin remodeling via RhoA signaling modulation. In conclusion, ibuprofen showed not only anti-inflammatory function, but also RhoA inhibition in articular chondrocytes.

Cartilage and Bone Destruction in Arthritis: Pathogenesis and Treatment Strategy: A Literature Review

Arthritis is inflammation of the joints accompanied by osteochondral destruction. It can take many forms, including osteoarthritis, rheumatoid arthritis, and psoriatic arthritis. These diseases share one commonality—osteochondral destruction based on inflammation. The background includes a close interaction between osseous tissues and immune cells through various inflammatory cytokines. However, the tissues and cytokines that play major roles are different in each disease, and as a result, the mechanism of osteochondral destruction also differs. In recent years, there have been many findings regarding not only extracellular signaling pathways but also intracellular signaling pathways. In particular, we anticipate that the intracellular signals of osteoclasts, which play a central role in bone destruction, will become novel therapeutic targets. In this review, we have summarized the pathology of arthritis and the latest findings on the mechanism of osteochondral destruction, as well as present and future therapeutic strategies for these targets.

Glucocorticoid signaling and osteoarthritis

Glucocorticoids are steroid hormones synthesized and released by the adrenal cortex. Their main function is to maintain cell homeostasis through a variety of signaling pathways, responding to changes in an organism's environment or developmental status. Mimicking the actions of natural glucocorticoids, synthetic glucocorticoids have been recruited to treat many diseases that implicate glucocorticoid receptor signaling such as osteoarthritis. In osteoarthritis, synthetic glucocorticoids aim to alleviate inflammation and pain. The variation of patients' response and the possibility of complications associated with their long-term use have led to a need for a better understanding of glucocorticoid receptor signaling in osteoarthritis. In this review, we performed a literature search in the molecular pathways that link the osteoarthritic joint to the glucocorticoid receptor signaling. We hope that this information will advance research in the field and propose new molecular targets for the development of more optimized therapies for osteoarthritis.

Restoring the IL-1β/NF-κB-induced impaired chondrogenesis by diallyl disulfide in human adipose-derived mesenchymal stem cells via attenuation of reactive oxygen species and elevation of antioxidant enzymes

Strategies based on mesenchymal stem cell (MSC) therapy for restoring injured articular cartilage are not effective enough in osteoarthritis (OA). Due to the enhanced inflammation and oxidative stress in OA microenvironment, differentiation of MSCs into chondrocytes would be impaired. This study aims to explore the effects of diallyl disulfide (DADS) on IL-1β-mediated inflammation and oxidative stress in human adipose derived mesenchymal stem cells (hADSCs) during chondrogenesis. MTT assay was employed to examine the effects of various concentrations of DADS on the viability of hADSCs at different time scales to obtain non-cytotoxic concentration range of DADS. The effects of DADS on IL-1β-induced intracellular ROS generation and lipid peroxidation were evaluated in hADSCs. Western blotting was used to analyze the protein expression levels of IκBα (np), IκBα (p), NF-κB (np) and NF-κB (p). Furthermore, the gene expression levels of antioxidant enzymes in hADSCs and chondrogenic markers at days 7, 14 and 21 of differentiation were measured using qRT-PCR. The results showed that addition of DADS significantly enhanced the mRNA expression levels of antioxidant enzymes as well as reduced ROS elevation, lipid peroxidation, IκBα activation and NF-κB nuclear translocation in hADSCs treated with IL-1β. In addition, DADS could significantly increase the expression levels of IL-1β-induced impaired chondrogenic marker genes in differentiated hADSCs. Treatment with DADS may provide an effective approach to prevent the pro-inflammatory cytokines and oxidative stress as catabolic causes of chondrocyte cell death and enhance the protective anabolic effects by promoting chondrogenesis associated gene expressions in hADSCs exposed to OA condition.

Therapeutics in Osteoarthritis Based on an Understanding of Its Molecular Pathogenesis

Osteoarthritis (OA) is the most prevalent joint disease in older people and is characterized by the progressive destruction of articular cartilage, synovial inflammation, changes in subchondral bone and peri-articular muscle, and pain. Because our understanding of the aetiopathogenesis of OA remains incomplete, we haven’t discovered a cure for OA yet. This review appraises novel therapeutics based on recent progress in our understanding of the molecular pathogenesis of OA, including pro-inflammatory and pro-catabolic mediators and the relevant signalling mechanisms. The changes in subchondral bone and peri-articular muscle accompanying cartilage damage are also reviewed.

Effect of epigallocatechin-3-o-gallate and quercetin on the cryopreservation of cartilage tissue

The effects of epigallocatechin-3-o-gallate (EGCG) and quercetin on the contents of extracellular matrix (ECM) in porcine cartilage at 4 °C were investigated. The addition of quercetin at 0.01 mM for the incubation of porcine cartilage disks at 4 °C for 2 week could suppress the decrease in ECM and the compliance of the disks, markedly greater than those of EGCG (1.0 mM).

ADAMTS4 and Oxidative/Antioxidative Status in Preterm Premature Rupture of Membranes

AIM

To determine the function of a disintegrin and metalloproteinase with thrombospondin motifs-4 (ADAMTS4), total oxidant status (TOS), total antioxidant status (TAS), and aryl esterase (ARES) in preterm premature rupture of membranes (PPROM) and to investigate the association with premature rupture of membranes (PROMs).

MATERIAL AND METHODS

58 pregnant women were included in this prospective study which comprised 29 PPROM patients as the study group and 29 patients, having healthy amniotic membranes, as the control group. ADAMTS4, TAS, TOS, and ARES levels were studied in the amniotic membrane homogenates of the patients.

RESULTS

ADAMTS4, TAS TOS, and ARES levels of amniotic membrane lysates were significantly different between PPROM and control groups (p < 0.001, p < 0.001, p = 0.008 and p = 0.002, respectively). Increased amniotic membrane ADAMTS4 (OR: 1.051 95% CI 1.006-1.098, p = 0.024) and TOS (OR: 12.777 95% CI 1.595-102.323, p = 0.016) were found to be significantly associated with the increased risk of PPROM.

CONCLUSION

ADAMTS4, TOS, and ARES levels were higher and TAS level was lower in PPROM patients than the normal healthy control group which had healthy amniotic membranes at term. As a result, ADAMTS4 may have a role in the pathogenesis by causing increased oxidative and inflammatory environment in PPROM.

TLR2 and AP-1/NF-kappaB are involved in the regulation of MMP-9 elicited by heat killed Listeria monocytogenes in human monocytic THP-1 cells

BACKGROUND

MMP-9 is crucial for a normal immune response, but excessive release of this enzyme leads to severe tissue damage. Listeria monocytogenes (LM) is an opportunistic food-borne pathogen causing listerosis, meningitis and sepsis. Heat killed Listeria monocytogenes (HKLM) activates immune system and leads production of cytokines and chemokines. However, nothing is known about the involvement of HKLM in MMP-9 regulation. Therefore we investigated the role of HKLM in the regulation of MMP-9 gene expression in THP-1 cells.

METHODS

Commercially available heat killed Listeria monocytogenes was used in this study. HKLM-induced MMP-9 expression was assessed with quantitative real-time qPCR and ELISA. Action of HKLM in different signaling pathways were studied by using THP-1-XBlue™ cells (THP-1-cells with NF-κB/AP-1 reporter construct), THP-1-XBlue™-defMyD cells (MyD88(-/-) THP-1 cells), anti-TLR2 mAb and pharmacological inhibitors. Phospho and total proteins were determined by Western blotting.

RESULTS

Increased MMP-9 production (mRNA: 395-Fold; Protein: 8141 pg/ml; P < 0.05) was observed in HKLM stimulated THP-1 cells as compared to the un-stimulated THP-1 cells. This production of MMP-9 was completely abrogated by anti-TLR2 blocking mAb (P = 0.0024). Furthermore, THP-1-XBlue™-defMyD cells were unable to produce MMP-9 in response to HKLM. HKLM- induced activation of NF-kappaB/AP-1 was also observed in THP-1-XBlue™ Cells. In addition, inhibitors of JNK (SP600125), MEK/ERK (U0126; PD98056), p38 MAPK (SB203580) and NF-kappaB (BAY 11-7085, Triptolide and Resveratrol) significantly suppressed (P < 0.05) HKLM-stimulated MMP-9 expression.

CONCLUSION

Our results indicate that HKLM activates TLR2 and NF-κB/AP-1 signaling pathways, leading to up-regulation of MMP-9 production in THP-1 cells. Thus, MMP-9 could be an appropriate therapeutic target to stop severe tissue damage caused by infection or chronic inflammation.

Disruption of phosphoinositide-specific phospholipases Cγ1 contributes to extracellular matrix synthesis of human osteoarthritis chondrocytes

Osteoarthritis (OA) is a degenerative joint disease characterized by articular cartilage degradation including extracellular matrix (ECM) degradation and cell loss. It is known that phosphoinositide-specific phospholipase γ1 (PLCγ1) can trigger several signaling pathways to regulate cell metabolism. However, whether this kinase is expressive and active in human OA chondrocytes and its role in the pathological progression of OA have not been investigated. The current study was designed to investigate the PLCγ1 expression in human OA cartilage, and whether PLCγ1 was involved in the ECM synthesis had been further explored using cultured human OA chondrocytes. Our results indicated that PLCγ1 was highly expressed in human OA chondrocytes. In our further study using the cultured human OA chondrocytes, the results demonstrated that the disruption of PLCγ1 by its inhibitor, U73122, and siRNA contributed to the ECM synthesis of human OA chondrocytes through regulating the expression of ECM-related signaling molecules, including MMP-13, Col II, TIMP1, Sox-9, and AGG. Furthermore, PLCγ1/IP3/Ca2+/CaMK II signaling axis regulated the ECM synthesis of human chondrocytes through triggering mTOR/P70S6K/S6 pathway. In summary, our results suggested that PLC-γ1 activities played an important role in the ECM synthesis of human OA chondrocytes, and may serve as a therapeutic target for treating OA.

Anabolic/Catabolic balance in pathogenesis of osteoarthritis: identifying molecular targets

Osteoarthritis is the most common degenerative musculoskeletal disease. In healthy cartilage, a low turnover of extracellular matrix molecules occurs. Proper balance of anabolic and catabolic activities is thus crucial for the maintenance of cartilage tissue integrity and for the repair of molecular damages sustained during daily usage. In persons with degenerative diseases such as osteoarthritis, this balance of anabolic and catabolic activities is compromised, and the extent of tissue degradation predominates over the capacity of tissue repair. This mismatch eventually results in cartilage loss in persons with osteoarthritis. Tissue homeostasis is controlled by coordinated actions and crosstalk among a number of proanabolic and antianabolic and procatabolic and anticatabolic factors. In osteoarthritis, an elevation of antianabolic and catabolic factors occurs. Interestingly, anabolic activity is also increased, but this response fails to repair the tissue because of both quantitative and qualitative insufficiency. This review presents an overview of the anabolic and catabolic activities involved in cartilage degeneration and the interplay among different signaling and metabolic factors. Understanding the basic molecular mechanisms responsible for tissue degeneration is critical to identifying and developing means to efficiently block or reverse the pathobiological symptoms of osteoarthritis.

Role of Sp1 transcription factor in Interleukin-1-induced ADAMTS-4 (aggrecanase-1) gene expression in human articular chondrocytes

Proinflammatory cytokines such as interleukin-1 beta (IL-1β) stimulate cartilage extracellular matrix aggrecan degradation by aggrecanases or ADAMTS (a disintegrin and metalloproteinase with thrombospondin motif) during the pathogenesis of arthritis. Human aggrecanase-1 (ADAMTS-4) gene promoter contains at least one specificity protein-1 (Sp1)-transcription factor-binding site. We investigated the previously unknown role of Sp1 in the regulation of ADAMTS-4 gene expression in human articular chondrocytes. Mithramycin and WP631, the specific inhibitors of guanine cytosine (GC)-rich Sp1 DNA binding, partially suppressed IL-1-induced ADAMTS-4 expression and activity. Genetic inhibition of Sp1 by antisense oligonucleotide or by small interfering RNA (siRNA)-mediated Sp1 knockdown partially inhibited ADAMTS-4 induction by IL-1. Sense oligonucleotide and negative control siRNA had no effect. In contrast, cytomegalovirus promoter-driven Sp1 overexpression further enhanced IL-1-induced ADAMTS-4 expression and activity. Constitutively expressed glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was not affected by any of the agents. These results provide pharmacological and genetic evidence for the importance of Sp1 in ADAMTS-4 gene regulation by IL-1. Thus, Sp1 could be potentially targeted to reduce arthritis-associated cartilage aggrecan loss.

Involvement of H-Ras and reactive oxygen species in proinflammatory cytokine-induced matrix metalloproteinase-13 expression in human articular chondrocytes

Proinflammatory cytokines such as interleukin-1 beta (IL-1β) and tumor necrosis factor alpha (TNF-α) enhance degradation of cartilage-specific, type II collagen by matrix metalloproteinase-13 (MMP-13). We investigated the previously unknown role of H-Ras and reactive oxygen species (ROS) in the cytokine induction of MMP-13 gene expression in human articular chondrocytes by using pharmacological inhibitors, RNA interference (RNAi) and antioxidants. Manumycin A, an inhibitor of H-Ras farnesylation by farnesyltransferase, suppressed IL-1β- and TNF-α-induced MMP-13 mRNA and protein expression. Small interfering RNA (siRNA)-mediated H-Ras silencing down-regulated MMP-13 mRNA and protein induction by IL-1β and TNF-α. Nicotinamide adenine dinucleotide phosphate oxidase (NADPH oxidase/NOX) inhibitor, diphenyleneiodonium (DPI) suppressed cytokine-induced MMP-13 expression and superoxide production. Apocynin, another NOX inhibitor, also diminished MMP-13 induction. Deoxyglucose an antimetabolite of glucose metabolism reduced MMP-13 increase. Role of NOX-mediated ROS production was reaffirmed by the observation that the antioxidants, trolox, nordihydroguaiaretic acid (NDGA), quercetin and resveratrol downregulated cytokine-induced MMP-13 mRNA and protein expression. These results provide strong pharmacological and genetic evidence for the implication of H-Ras and NADPH oxidase-generated superoxide production in MMP-13 gene regulation by IL-1β and TNF-α. These proteins could be potentially targeted for therapeutic inhibition of MMP-13-driven cartilage erosion by using H-Ras and NOX inhibitors and antioxidants.

The role of ADAMTSs in arthritis

The ADAMTS (a disintegrin and metalloproteinase with thrombospondin motifs) family consists of 19 proteases. These enzymes are known to play important roles in development, angiogenesis and coagulation; dysregulation and mutation of these enzymes have been implicated in many disease processes, such as inflammation, cancer, arthritis and atherosclerosis. This review briefly summarizes the structural organization and functional roles of ADAMTSs in normal and pathological conditions, focusing on members that are known to be involved in the degradation of extracellular matrix and loss of cartilage in arthritis, including the aggrecanases (ADAMTS-4 and ADAMTS-5), ADAMTS-7 and ADAMTS-12, the latter two are associated with cartilage oligomeric matrix protein (COMP), a component of the cartilage extracellular matrix (ECM). We will discuss the expression pattern and the regulation of these metalloproteinases at multiple levels, including their interaction with substrates, induction by pro-inflammatory cytokines, protein processing, inhibition (e.g., TIMP-3, alpha-2-macroglobulin, GEP), and activation (e.g., syndecan-4, PACE-4).

Matrilin-3 activates the expression of osteoarthritis-associated genes in primary human chondrocytes

Here, we tested the matrilin-3-dependent induction of osteoarthritis-associated genes in primary human chondrocytes. Matrilin stimulation leads to the induction of MMP1, MMP3, MMP13, COX-2, iNOS, IL-1beta, TNFalpha, IL-6 and IL-8. Furthermore, we show the participation of ADAMTS4 and ADAMTS5 in the in vitro degradation of matrilin-3. We provide evidence for a matrilin-3-dependent feed-forward mechanism of matrix degradation, whereby proteolytically-released matrilin-3 induces pro-inflammatory cytokines as well as ADAMTS4 and -5 indirectly via IL-1beta. ADAMTS4 and ADAMTS5, in turn, cleave matrilin-3 and may release more matrilin-3 from the matrix, which could lead to further release of pro-inflammatory cytokines and proteases in cartilage.