Interleukin (IL)-36 is a family of cytokines that belongs to the larger IL-1 superfamily. IL-36 agonist/antagonist binds to the interleukin-36 receptor involving in physiological inflammation regulation and pathogenesis of many inflammatory diseases. In inflammatory joint diseases, the expression of IL-36 changes, and some studies have initially explored the role of IL-36 in these diseases. In psoriatic arthritis, IL-36 signal mediates plasma cell and fibroblast-like synoviocyte crosstalk presenting IL-36 agonist/antagonist imbalance. In rheumatoid arthritis, IL-36 agonists induce fibroblast-like synoviocyte to produce pro-inflammatory factors, while IL-36 antagonist deficiency leads to lesion progression. In osteoarthritis, IL-36 agonists induce chondrocytes to produce catabolic enzymes and pro-inflammatory factors. This article reviews the expression and function of IL-36 in different inflammatory joint diseases to provide a reference for revealing their pathogenic mechanisms and discovering therapeutic targets.
Humans ; Interleukins ; Arthritis, Rheumatoid ; Osteoarthritis/pathology* ; Arthritis, Psoriatic/metabolism* ; Cytokines

The Wnt signaling exists in every kinds of species and regulates a variety of biological processes including cell fate, proliferation and function, immunity, stress, apoptosis and so on. During the researching, Wnt signaling also plays an important role in chondrocyte differentiation and maturation. So it has been the new spot in pathogenesis of osteoarthritis study.
Animals ; Chondrocytes ; metabolism ; pathology ; Humans ; Osteoarthritis ; metabolism ; pathology ; Signal Transduction ; Wnt Proteins ; metabolism

The progressive destruction of condylar cartilage is a hallmark of the temporomandibular joint (TMJ) osteoarthritis (OA); however, its mechanism is incompletely understood. Here, we show that Kindlin-2, a key focal adhesion protein, is strongly detected in cells of mandibular condylar cartilage in mice. We find that genetic ablation of Kindlin-2 in aggrecan-expressing condylar chondrocytes induces multiple spontaneous osteoarthritic lesions, including progressive cartilage loss and deformation, surface fissures, and ectopic cartilage and bone formation in TMJ. Kindlin-2 loss significantly downregulates the expression of aggrecan, Col2a1 and Proteoglycan 4 (Prg4), all anabolic extracellular matrix proteins, and promotes catabolic metabolism in TMJ cartilage by inducing expression of Runx2 and Mmp13 in condylar chondrocytes. Kindlin-2 loss decreases TMJ chondrocyte proliferation in condylar cartilages. Furthermore, Kindlin-2 loss promotes the release of cytochrome c as well as caspase 3 activation, and accelerates chondrocyte apoptosis in vitro and TMJ. Collectively, these findings reveal a crucial role of Kindlin-2 in condylar chondrocytes to maintain TMJ homeostasis.
Aggrecans/metabolism* ; Animals ; Cartilage, Articular/metabolism* ; Chondrocytes/pathology* ; Cytoskeletal Proteins/metabolism* ; Mice ; Muscle Proteins/metabolism* ; Osteoarthritis/pathology* ; Temporomandibular Joint/pathology*

Osteoarthritis (OA) is a prevalent degenerative joint disease characterized by cartilage loss and accounts for a major source of pain and disability worldwide. However, effective strategies for cartilage repair are lacking, and patients with advanced OA usually need joint replacement. Better comprehending OA pathogenesis may lead to transformative therapeutics. Recently studies have reported that exosomes act as a new means of cell-to-cell communication by delivering multiple bioactive molecules to create a particular microenvironment that tunes cartilage behavior. Specifically, exosome cargos, such as noncoding RNAs (ncRNAs) and proteins, play a crucial role in OA progression by regulating the proliferation, apoptosis, autophagy, and inflammatory response of joint cells, rendering them promising candidates for OA monitoring and treatment. This review systematically summarizes the current insight regarding the biogenesis and function of exosomes and their potential as therapeutic tools targeting cell-to-cell communication in OA, suggesting new realms to improve OA management.
Apoptosis ; Cartilage/pathology* ; Cartilage, Articular/metabolism* ; Cell Communication ; Chondrocytes/metabolism* ; Exosomes/pathology* ; Humans ; Osteoarthritis/therapy*

OBJECTIVE: To detect the changes of mitochondrion DNA (mtDNA) sequence in articular chondrocytes of cartilage affected by osteoarthritis and to clarified the pathogenetic mechanism of osteoarthritis. METHODS: We analyzed the mtDNA 4,977 bp deletion mutations of articular chondrocytes in 10 patients with osteoarthritis and 3 normal cartilages using the gap-PCR amplification method. We designed a two round PCR detection method, in which total DNA was isolated from articular chondrocytes as the template of the first round PCR reaction and products from the first round were the template in the second round reaction. RESULTS: The results of the first rounds of PCR reaction showed the mtDNA 524 bp amplified products in the osteoarthritis group and in the corresponding peripheral blood samples were not detected, but the 533 bp products were detected. However,the results of the second round reaction revealed that the 524 bp zones were detected in 2 of the 10 osteoarthritis patients and the corresponding peripheral blood samples were not detected. The 533 bp products were detected in all specimens. The mtDNA 524 bp amplified products in all the normal articular chondrocytes and the corresponding peripheral white blood cells contrast were not detected in both rounds PCR. CONCLUSION This was the first study to evaluate the mtDNA 4799 bp large fragment deletion mutational accumulation between nt8,470 - nt13,447 of articular chondrocytes in osteoarthritic cartilage. Osteoarthritis may be related to mtDNA mutation of articular chondrocytes.
Adult ; Cartilage, Articular ; metabolism ; pathology ; Chondrocytes ; metabolism ; DNA, Mitochondrial ; genetics ; Female ; Gene Deletion ; Humans ; Male ; Middle Aged ; Osteoarthritis ; genetics ; Osteoarthritis, Hip ; genetics ; Osteoarthritis, Knee ; genetics ; Sequence Analysis, DNA

OBJECTIVETo investigate the gene expression and potential functions of transforming growth factor-beta1 in osteophyte development.

METHODSA total of 25 specimens were obtained from individuals undergoing total knee arthroplasty due to severe primary osteoarthritis. Tissue samples were embedded in paraffin wax and made into sections. Hematoxylin and eosin and toluidine blue stainings were performed. The expressions of collagen I, IIa, IIb, and X were detected by immunohistochemistry. Based on the histomorphology of cellularity and matrix abundance, the glycosaminoglycans content, and the differential expressions of collagen I, IIa, IIb, and X, the osteophytic tissues were classified. For each different type of osteophyte, expressions of transforming growth factor-beta1 were detected by immunohistochemistry and in situ hybridization, and results were analyzed using the image analysis system.

RESULTSFive different types of osteophytes were identified as type I, type II, type III, type IV, and type V. Transforming growth factor-beta1 mRNA was more and intensely expressed in chondrocytes of type II and III osteophytes, and was less in other types of osteophytes. The difference was significant (P<0.05, P<0.01).

CONCLUSIONTransforming growth factor-beta1 mRNA is mainly expressed in early-mid stages of osteophytes and may play an important role in promoting the proliferation and differentiation of chondrocytes in the early stages of osteophyte development.

Chondrocytes ; metabolism ; pathology ; Humans ; Osteoarthritis, Knee ; metabolism ; pathology ; Osteophyte ; metabolism ; pathology ; RNA, Messenger ; biosynthesis ; Transforming Growth Factor beta1 ; biosynthesis ; genetics

Osteoarthritis is a common cause of functional deterioration in older adults and is an immense burden on the aging population. Altered chondrogenesis is the most important pathophysiological process involved in the development of osteoarthritis. However, the molecular mechanism underlying the regulation of chondrogenesis in patients with osteoarthritis requires further elucidation, particularly with respect to the role of microRNAs. MiR-21 expression in cartilage specimens was examined in 10 patients with knee osteoarthritis and 10 traumatic amputees. The effect of miR-21 on chondrogenesis was also investigated in a chondrocyte cell line. The effect of miR-21 on the expression of growth differentiation factor 5 (GDF-5) was further assessed by luciferase reporter assay and western blot. We found that endogenous miR-21 is upregulated in osteoarthritis patients, and overexpression of miR-21 could attenuate the process of chondrogenesis. Furthermore, we identified GDF-5 as the direct target of miR-21 during the regulation of chondrogenesis. Our data suggest that miR-21 has an important role in the pathogenesis of osteoarthritis and is a potential therapeutic target.
Cartilage/metabolism/pathology ; Case-Control Studies ; Cell Line ; Chondrocytes/*metabolism/pathology ; Growth Differentiation Factor 5/genetics/*metabolism ; Humans ; MicroRNAs/genetics/*metabolism ; Osteoarthritis/*metabolism/pathology ; Up-Regulation

OBJECTIVETo study the characteristics of cellular metabolism of mandibular condylar chondrocytes in repairing state of osteoarthrosis and investigate its role in the pathogenesis of the disease.

METHODSTemporomandibular joint osteoarthrosis model of rabbits was created by the partial resection of joint disc and confirmed with histological diagnosis. The chondrocytes were harvested from osteoarthritic condylar cartilage in the repairing state and cultured in vitro under the monolayer culture condition. The cellular expression of cartilaginous matrix protein, collagenase and growth factors between the osteoarthritic chondrocytes and the normal controls were measured with RT-PCR technique to outline the basic feature of the osteoarthritic cells.

RESULTSThe cultured cells were confirmed as chondrocytes with their ability of expression of collagen type II and Aggrecan. In the reactive repairing state of osteoarthrosis, the chondrocytes showed the imbalance of expression of ECM proteins, and increased expression of collagenase and endogenous growth factors such as IGF-1 and TGF-beta1.

CONCLUSIONSThis study found the active anabolism of the chondrocytes within the osteoarthritic condylar cartilage and the imbalance synthesis of cartilage matrix. These repairing attempts by the osteoarthritic chondrocytes may be impossible to restore the primary homeostasis within the condylar cartilage.

Animals ; Cartilage, Articular ; metabolism ; pathology ; Cells, Cultured ; Chondrocytes ; metabolism ; Extracellular Matrix ; genetics ; metabolism ; Male ; Mandibular Condyle ; metabolism ; pathology ; Osteoarthritis ; metabolism ; pathology ; RNA, Messenger ; genetics ; metabolism ; Rabbits ; Temporomandibular Joint Disc ; pathology ; Temporomandibular Joint Disorders ; metabolism ; pathology

Calcium Pyrophosphate ; metabolism ; Cartilage, Articular ; metabolism ; pathology ; Chondrocalcinosis ; diagnostic imaging ; metabolism ; pathology ; surgery ; Diagnosis, Differential ; Female ; Gout ; pathology ; Humans ; Knee Joint ; diagnostic imaging ; metabolism ; pathology ; Male ; Menisci, Tibial ; metabolism ; pathology ; Middle Aged ; Osteoarthritis ; etiology ; pathology ; Radiography

OBJECTIVETo explore the expression of interleukin 18 (IL-18) and prostaglandin E2 (PGE2) and their relationship in the synoviocytes of patients with osteoarthritis (OA).

METHODSThe synovial tissues were obtained from 30 OA patients to isolate the synoviocytes for primary culture. The concentrations of IL-18 and PGE2 in the supernatants of synoviocyte culture were measured by enzyme-linked immunosorbent assay (ELISA).

RESULTSThe concentration of IL-18 averaged 51.559-/+27.614 pg/ml and PGE2 327.036-/+333.561 pg/ml in the supernatant of the synoviocytes. A significant positive correlation was noted between their expressions (r=0.863, P<0.01).

CONCLUSIONIL-18 may induce the production of PGE2, and their interactions they may play an important role in the pathogenesis of OA.

Adult ; Aged ; Aged, 80 and over ; Cells, Cultured ; Dinoprostone ; metabolism ; Female ; Humans ; Interleukin-18 ; metabolism ; Male ; Middle Aged ; Osteoarthritis ; metabolism ; pathology ; Synovial Membrane ; metabolism ; pathology