Naproxen, meloxicam and methylprednisolone inhibit urokinase plasminogen activator and inhibitor and gelatinases expression during the early stage of osteoarthritis

Chondrotoxicity of Intra-Articular Injection Treatment: A Scoping Review

The purpose of this scoping review was to identify possible chondrotoxic effects caused by drugs usually used for intra-articular injections. PubMed, Scopus, Web of Science and Cochrane were searched. Inclusion criteria required randomized controlled trials written in English that evaluate the toxic effect that damages the cartilage. The literature search resulted in 185 unique articles. 133 full-text articles were screened for inclusion, of which 65 were included. Corticosteroids, with the exception of triamcinolone, along with local anaesthetics, potentially excluding ropivacaine and liposomal bupivacaine, and nonsteroidal anti-inflammatory drugs, exhibited insufficient safety profiles to warrant casual use in clinical settings. Hyaluronic acid, on the other hand, appears to demonstrate safety while also mitigating risks associated with concurrent compounds, thereby facilitating therapeutic combinations. Additionally, there remains a paucity of data regarding platelet-rich plasma, necessitating further evaluation of its potential efficacy and safety. Overall, it seems that results are significantly influenced by the dosage and frequency of injections administered, observed in both human and animal studies.

Corticosteroid injections for the treatment of osteoarthritis present a wide spectrum of effects ranging from detrimental to disease-modifying: A systematic review of preclinical evidence by the ESSKA Orthobiologic Initiative

PURPOSE

Aim of this systematic review of preclinical evidence was to determine the effects of intra-articular corticosteroid (CS) injections in joints affected by osteoarthritis (OA).

METHODS

A systematic review was performed on animal studies evaluating intra-articular CS injections for OA joints. The search was performed on PubMed, Cochrane, and Web of Science databases. A synthesis of the results was performed investigating CS effects by evaluating studies comparing CS with control groups. Morphological, histological, immunohistochemistry evaluations, clinical outcomes, biomarkers and imaging results were evaluated. The risk of bias was assessed according to the Systematic Review Centre for Laboratory Animal Experimentation's tool.

RESULTS

Thirty-two articles analysing CS effects in OA animal models were included (1079 joints), 18 studies on small and 14 on large animals. CS injections showed overall positive effects in at least one of the outcomes in 68% of the studies, while 16% reported a deleterious effect. CS improved cartilage and synovial outcomes in 68% and 60% of the studies, but detrimental effects were documented in 11% and 20% of the studies, respectively. Clinical parameters evaluated in terms of pain, lameness or joint swelling improved in 63% of the studies but deteriorated in 13%. Evidence is limited on imaging and biomarkers results, as well as on the best CS type, dose, formulation and injection protocol. The risk of bias assessment revealed a 28% low and an 18% high risk of bias.

CONCLUSION

Intra-articular CS injections induced a wide range of results on OA joints in experimental animal models, from disease-modifying and positive effects on pain and joint function at short-term evaluation to the lack of benefit or even negative effects. This underlines the need to identify more specific indications and treatment modalities to avoid possible detrimental effects while maximising the anti-inflammatory properties and the benefits of intra-articular CS in OA joints.

LEVEL OF EVIDENCE

Level II.

In Vitro Effects of Triamcinolone and Methylprednisolone on the Viability and Mechanics of Native Articular Cartilage

BACKGROUND

The chondrotoxic effects of methylprednisolone acetate (MP) and triamcinolone acetonide (TA) have been well described. However, the mechanical effects of these commonly used steroids on native cartilage are largely unknown.

PURPOSE

To investigate the in vitro effects of a single 1-hour MP or TA exposure on the viability, mechanics, and biochemical content of native articular cartilage explants.

STUDY DESIGN

Controlled laboratory study.

METHODS

Articular cartilage explants (n = 6 per group) were harvested from the femoral condyles of bovine stifles. Explants were exposed to chondrogenic medium containing a clinical dose of MP or TA for 1 hour, followed by fresh medium wash and exchange. Explants in the control group underwent the same treatment with chondrogenic medium alone. At 24 hours after treatment, samples were assessed for viability (live/dead), mechanical properties (creep indentation and Instron tensile testing), biochemical (collagen and glycosaminoglycan) content, and pyridinoline crosslinking via mass spectrometry.

RESULTS

Mean cell viability was significantly decreased in native explants exposed to MP (35.5%) compared with the control (49.8%; P < .001) and TA (45.7%; P = .01) specimens. Significant decreases were seen in the mechanical properties of steroid-treated native explants when compared with controls, with decreases in aggregate modulus (646.3 vs 312.8 kPa [MP] and 257.0 kPa [TA]; P < .001), shear modulus (370.1 vs 191.2 kPa [MP] and 157.4 kPa [TA]; P < .001), and ultimate tensile strength (9.650 vs 5.648 MPa [MP; P = .021] and 6.065 MPa [TA; P = .0403]). No significant differences in collagen and glycosaminoglycan content were found in the steroid-treated groups. Pyridinoline crosslinking was significantly decreased in explants exposed to TA compared with controls (P = .027).

CONCLUSION

Exposure of MP to articular cartilage explants was chondrotoxic, and exposure of articular cartilage explants to MP or TA resulted in significant decreases in mechanical properties of articular cartilage explants compared with controls. Clinicians should be judicious regarding use of intra-articular steroids, particularly in patients with intact healthy articular cartilage.

Different molecular weights of hyaluronan research in knee osteoarthritis: A state-of-the-art review

Osteoarthritis (OA), the most common form of arthritis, is characterized by progressive cartilage destruction, concomitant adaptive osteogenesis, and loss of joint function. The progression of OA with aging is associated with a decrease in native hyaluronan (HA, hyaluronate or hyaluronic acid) with a high molecular weight (HMW) in synovial fluid and a subsequent increase in lower MW HA and fragments. As HMW HA possesses numerous biochemical and biological properties, we review new molecular insights into the potential of HA to modify OA processes. Different MWs in the formulation of products appear to have varying effects on knee OA (KOA) pain relief, improved function, and postponing surgery. In addition to the safety profile, more evidence indicates that intraarticular (IA) HA administration may be an effective option to treat KOA, with a particular emphasis on the use of HA with fewer injections of higher MW, including potential applications of HA of very HMW. We also analyzed published systemic reviews and meta-analyses of IA HA in treating KOA in order to discuss their conclusions and consensus statements. According to its MW, HA may offer a simple way to refine therapeutic information in selective KOA.

In vivo joint synovial fluid disposition of a novel sustained-release formulation of diclofenac and hyaluronic acid in horses

Intra-articular administration of sustained-release anti-inflammatory drugs is indicated in horses suffering from joint inflammation, but no such drugs are labelled for veterinary use. To obtain initial data on synovial disposition and safety of a new sustained-release formulation of diclofenac (SYN321) in the joints of horses, an experimental interventional study of elimination and side effects of intra-articular administration of SYN321 was conducted. Nine clinically sound horses were included in the study, and SYN321 was administered by the intra-articular route. Dose ranges and sampling intervals were established in a pilot study with two horses, and then applied in a main study involving seven horses treated in the fetlock joint. Diclofenac was detected above lower limit of quantification (LOQ: 0.5 ng/ml) in synovial fluid throughout the study period (14 days), and below LOQ (0.1 ng/ml) in plasma after 4 days and in urine after 14 days. No obvious clinical side effects were detected. Clinical examination and objective lameness evaluation suggested that SYN321 has potential as a local joint NSAID treatment with sustained release in horses, but further studies on synovial fluid exposure, safety and clinical efficacy are warranted.

The potential remedy of melatonin on osteoarthritis

Osteoarthritis (OA), the most common arthritis worldwide, is a degenerative joint disease characterized by progressive cartilage breakdown, subchondral remodeling, and synovial inflammation. Although conventional pharmaceutical therapies aimed to prevent further cartilage loss and joint dysfunction, there are no ideal strategies that target the pathogenesis of OA. Melatonin exhibits a variety of regulatory properties by binding to specific receptors and downstream molecules and exerts a myriad of receptor-independent actions via intracellular targets as a chondrocyte protector, an anti-inflammation modulator, and a free radical scavenger. Melatonin also modulates cartilage regeneration and degradation by directly/indirectly regulating the expression of main circadian clock genes, such as transcriptional activators [brain and muscle aryl hydrocarbon receptor nuclear translocator-like protein (Bmal) and circadian locomotor output cycles kaput (Clock)], transcriptional repressors [period circadian regulator (Per)1/2, cryptochrome (Cry)1/2, and Dec2], and nuclear hormone receptors [Rev-Erbs and retinoid acid-related orphan receptors (Rors)]. Owing to its effects on cartilage homeostasis, we propose a potential role for melatonin in the prevention and therapy of OA via the modulation of circadian clock genes, mitigation of chondrocyte apoptosis, anti-inflammatory activity, and scavenging of free radicals.

Identification of tissue-dependent proteins in knee OA synovial fluid

OBJECTIVE

For many proteins from osteoarthritic synovial fluid, their intra-articular tissue of origin remains unknown. In this study we performed comparative proteomics to identify osteoarthritis-specific and joint tissue-dependent secreted proteins that may serve as candidates for osteoarthritis biomarker development on a tissue-specific basis.

DESIGN

Protein secretomes of cartilage, synovium, Hoffa's fat pad and meniscus from knee osteoarthritis patients were determined using liquid chromatography tandem mass spectrometry, followed by label-free quantification. Validation of tissue-dependent protein species was conducted by ELISA on independent samples. Differential proteomes of osteoarthritic and non-osteoarthritic knee synovial fluids were obtained via similar proteomics approach, followed by ELISA validation.

RESULTS

Proteomics revealed 64 proteins highly secreted from cartilage, 94 from synovium, 37 from Hoffa's fat pad and 21 from meniscus. Proteomic analyses of osteoarthritic vs non-osteoarthritic knee synovial fluid revealed 70 proteins with a relatively higher abundance and 264 proteins with a relatively lower abundance in osteoarthritic synovial fluid. Of the 70 higher abundance proteins, 23 were amongst the most highly expressed in the secretomes of a specific intra-articular tissue measured. Tissue-dependent release was validated for SLPI, C8, CLU, FN1, RARRES2, MATN3, MMP3 and TNC. Abundance in synovial fluid of tissue-dependent proteins was validated for IGF2, AHSG, FN1, CFB, KNG and C8.

CONCLUSIONS

We identified proteins with a tissue-dependent release from intra-articular human knee OA tissues. A number of these proteins also had an osteoarthritis-specific abundance in knee synovial fluid. These proteins may serve as novel candidates for osteoarthritis biomarker development on a tissue-specific basis.

Naproxen platinum(iv) hybrids inhibiting cycloxygenases and matrix metalloproteinases and causing DNA damage: synthesis and biological evaluation as antitumor agents in vitro and in vivo

Cycloxygenases (COXs) and matrix metalloproteinases (MMPs) in the tumor microenvironment (TME) are tightly related to the progression of cancers. Here, naproxen as a potent inhibitor of both COX and MMP was combined with platinum(iv) to construct hybrids as antitumor agents. Compound 2 with comparable or even superior activities to that of cisplatin, oxaliplatin, and carboplatin, great potential for reversing drug resistance, and superior tumor targeting properties was screened out as a lead compound. Moreover, compound 2 possessed potent tumor growth inhibition capability in vivo, which was comparable to that of oxaliplatin, and displayed rather lower side effects than the platinum(ii) reference drugs. The naproxen platinum(iv) complex could easily undergo reduction and liberate the platinum(ii) complex and naproxen as well as exert a multifunctional antitumor mechanism: (i) the liberated platinum(ii) fragment would cause serious DNA injury; (ii) naproxen would inhibit COX-2 and decrease tumor-associated inflammation; and (iii) the naproxen platinum(iv) complex exhibited remarkable MMP-9 inhibition in tumor tissues. These antitumor functions can help reduce the growth and metastasis of malignancy.

Treatment recommendations for chronic knee osteoarthritis

Primary osteoarthritis (OA) hinders an aging global population as one of the leading causes of years-lost-to-disability (YLD). OA in most patients is considered to be an overuse injury that results in degenerative inflammation of the joints with the associated formation of bony outgrowths. Due to the escalating nature of this chronic pain disease, treatment management for OA can initially begin with a more conservative approach. It can eventually lead to more invasive surgical procedures. At present, the standard of care remains initial conservative management with lifestyle changes, including weight loss with concurrent anti-inflammatory regimens. Injections are frequently used for the escalation of care, but a significant number of patients ultimately resort to total knee arthroplasty. This review will focus specifically on knee OA, providing a brief overview of risk factors and early management and in-depth exploration of the invasive interventions that can offer symptomatic relief and return of function.

Analysis of Drug Effects on Primary Human Coronary Artery Endothelial Cells Activated by Serum Amyloid A

Background

RA patients have a higher incidence of cardiovascular diseases compared to the general population. Serum amyloid A (SAA) is an acute-phase protein, upregulated in sera of RA patients.

Aim

To determine the effects of medications on SAA-stimulated human coronary artery endothelial cells (HCAEC).

Methods

HCAEC were preincubated for 2 h with medications from sterile ampules (dexamethasone, methotrexate, certolizumab pegol, and etanercept), dissolved in medium (captopril) or DMSO (etoricoxib, rosiglitazone, meloxicam, fluvastatin, and diclofenac). Human recombinant apo-SAA was used to stimulate HCAEC at a final 1000 nM concentration for 24 hours. IL-6, IL-8, sVCAM-1, and PAI-1 were measured by ELISA. The number of viable cells was determined colorimetrically.

Results

SAA-stimulated levels of released IL-6, IL-8, and sVCAM-1 from HCAEC were significantly attenuated by methotrexate, fluvastatin, and etoricoxib. Both certolizumab pegol and etanercept significantly decreased PAI-1 by an average of 43%. Rosiglitazone significantly inhibited sVCAM-1 by 58%.

Conclusion

We observed marked influence of fluvastatin on lowering cytokine production in SAA-activated HCAEC. Methotrexate showed strong beneficial effects for lowering released Il-6, IL-8, and sVCAM-1. Interesting duality was observed for NSAIDs, with meloxicam exhibiting opposite-trend effects from diclofenac and etoricoxib. This represents unique insight into specific responsiveness of inflammatory-driven HCAEC relevant to atherosclerosis.

Therapeutic Review of Methylprednisolone Acetate Intra-Articular Injection in the Management of Osteoarthritis of the Knee - Part 1: Clinical Effectiveness

Intra-articular (IA) corticosteroid injections are a common approach in the management of osteoarthritis (OA) of the knee. The effectiveness of injections and particular injection products is often discussed and debated in clinical arenas. The following therapeutic review examines the evidence for intra-articular methylprednisolone acetate (MPA) injections in the management of OA knee. A review of research evidence, published guidelines and clinical literature was undertaken following an electronic database and relevant literature search. The review found that there is limited evidence which indicates that a single dose intra-articular MPA injection can provide short to medium term benefits for pain, with less evidence for beneficial effects on function or stiffness. There is heterogeneity across studies and until recently, most studies had only short to medium term follow-up periods, thus limiting the evidence available on longer term benefit. There was also evidence indicating equivalent overall efficacy of MPA to that of other corticosteroid products. Most guideline recommendations concerning IA injections for OA knee have drawn on evidence from pooled data for several corticosteroid products. The review also found there was limited reporting of the incidence of adverse events in most studies. Overall, MPA shows efficacy for symptom relief in OA knee. At an individual management level, evidence for a limited duration of effect needs consideration in injections decisions. Furthermore, consensus across clinical guidelines suggests that the management of OA knee should be individualized to a person's clinical history, degree of disability, risk factors, quality of life and personal preferences, whereby injecting involves a shared decision and forms part of a multimodal approach. Copyright © 2016 John Wiley & Sons Ltd.

The Effect of Intra-articular Corticosteroids on Articular Cartilage: A Systematic Review

Background:

Intra-articular (IA) corticosteroid therapy has been used for the treatment of inflammation and pain in the knee since the 1950s.

Purpose:

To review the current literature on the effects of IA corticosteroids on articular cartilage.

Study Design:

Systematic review.

Methods:

A MEDLINE and SCOPUS database search was performed, and studies were selected for basic science and clinical trial research on corticosteroids with direct outcome measures of cartilage health. Preliminary searches yielded 1929 articles, and final analysis includes 40 studies.

Results:

Methylprednisolone, dexamethasone, hydrocortisone, betamethasone, prednisolone, and triamcinolone were reported to display dose-dependent deleterious effects on cartilage morphology, histology, and viability in both in vitro and in vivo models. The beneficial animal in vivo effects of methylprednisolone, hydrocortisone, and triamcinolone occurred at low doses (usually <2-3 mg/dose or 8-12 mg/cumulative total dose in vivo), at which increased cell growth and recovery from damage was observed; the single human clinical trial indicated a beneficial effect of triamcinolone. However, at higher doses (>3 mg/dose or 18-24 mg/cumulative total dose in vivo), corticosteroids were associated with significant gross cartilage damage and chondrocyte toxicity. Dose and time dependency of corticosteroid chondrotoxicity was supported in the in vitro results, however, without clear dose thresholds.

Conclusion:

Corticosteroids have a time- and dose-dependent effect on articular cartilage, with beneficial effects occurring at low doses and durations and detrimental effects at high doses and durations. Clinically, beneficial effects are supported for IA administration, but the lowest efficacious dose should be used.

In vivo effects of phenylbutazone on inflammation and cartilage-derived biomarkers in equine joints with acute synovitis

Although phenylbutazone (PBZ) is commonly used in equine orthopaedic practice, little is known about its in vivo effects on joint inflammation and cartilage turnover. This study investigates the effects of PBZ on inflammatory parameters, matrix metalloproteinase (MMP) activity and cartilage biomarkers in equine joints with acute synovitis. In a two-period cross-over study, transient synovitis was induced at T = 0 h in the middle carpal joint of seven ponies by lipopolysaccharide (LPS) injection. Ponies received PBZ (2 mg/kg PO twice daily) or placebo for 1 week, starting at T = 2 h. Arthroscopic assessment of the middle carpal joint was performed at T = -504, 48 and 672 h. Synovial fluid (SF) was sampled at T = -504, 0, 8, 24, 48, 168, 336 and 672 h and analysed for leukocytes and total protein, substance P, general MMP activity, glycosaminoglycans (GAG), collagen II cleavage marker C2C and synthesis marker CPII. Markers in PBZ- vs. placebo-treated joints were compared over time using a linear mixed model. LPS injection caused marked transient synovitis without visible cartilage changes. Substance P and general MMP activity were not significantly reduced by PBZ treatment, nor were SF GAG or C2C concentrations at any time point. Concentration of CPII was significantly lower at T = 24 and 168 h in PBZ treated joints compared to placebo. Although PBZ is clinically effective in treating acute synovitis, it does not limit inflammation-induced cartilage catabolism and may transiently reduce collagen anabolism as evidenced by SF markers.

In vivo effects of meloxicam on inflammatory mediators, MMP activity and cartilage biomarkers in equine joints with acute synovitis

REASONS FOR PERFORMING STUDY

Meloxicam is a commonly used nonsteroidal anti-inflammatory drug in equine practice, but little is known about its in vivo effects on joint inflammation and cartilage turnover.

OBJECTIVES

To study the effects of meloxicam on biomarkers of inflammation, matrix metalloproteinase (MMP) activity, and cartilage biomarkers in joints with experimental synovitis.

METHODS

In a 2-period cross-over study, synovitis was induced at T = 0 h in the L or R intercarpal joint of 6 horses by intraarticular injection of 0.5 ng lipopolysaccharide (LPS). Horses received once daily meloxicam (0.6 mg/kg bwt per os) or placebo starting at post injection hour (PIH) 2, and clinical evaluations as well as blood and synovial fluid (SF) sampling were performed at PIH 0, 8, 24 and 168. Synovial fluid was analysed for prostaglandin E2, bradykinin, substance P, general MMP activity, glycosaminoglycans (GAG), CS846 epitope, type II collagen cleavage fragments (C2C) and type II collagen carboxypropeptide (CPII). Concentrations in meloxicam- vs. placebo-treated joints over time were compared using a linear mixed model.

RESULTS

Lipopolysaccharide injection caused marked transient synovitis without systemic effects. Meloxicam caused a significant reduction in lameness at PIH 8 and 24 and tended to reduce effusion. In addition, meloxicam significantly suppressed SF prostaglandin E2 and substance P release at PIH 8 and bradykinin at PIH 24 compared to placebo treatment. General MMP activity at PIH 8 and 24 was significantly lower in meloxicam- vs. placebo-treated joints, as were GAG, C2C and CPII concentrations at PIH 24.

CONCLUSIONS

Acute transient synovitis leads to substantial increases in SF biomarkers of inflammation, MMP activity and cartilage turnover, which can be significantly suppressed by meloxicam.

POTENTIAL RELEVANCE

Early oral treatment with meloxicam ameliorates not only clinical signs and joint inflammation in acute synovitis, but may also limit inflammation-induced cartilage catabolism.

Elevated level of tenascin and matrix metalloproteinase 9 correlates with the bone destruction capacity of cholesteatomas

OBJECTIVES

Bone destruction is a key step in the progression of cholesteatomas. Some of the lesions can grow without affecting the surrounding anatomic structures, whereas others can cause severe bone destruction despite their limited size. This study aims to identify factors that could play important role during the invasion of the disease.

METHODS

Cholesteatoma tissue samples were examined immunohistochemically. Tissue samples were arranged on the basis of bone destruction (destructive cholesteatomas [DC] and nondestructive cholesteatomas [NDC]). Double-immunofluorescent labeling was performed to detect simultaneously 1) tenascin (TN) and cytokeratin; 2) matrix metalloproteinase 9 (MMP-9) and TN; 3) TN and Ki-67. An in situ apoptosis detection kit was used to detect apoptotic cells. External auditory canal skin samples were used as control.

RESULTS

1) In DCs, more widespread stromal TN labeling was seen compared with NDCs or external auditory canal skin samples. 2) More enhanced MMP-9 staining was detected in DCs compared with NDCs. 3) The proportion of Ki-67-positive cells in DC samples was significantly higher than in NDCs. 4) The percentage of apoptotic cells was higher in NDC than in DC samples.

CONCLUSION

Our present study demonstrates that levels of TN, MMP-9, and proliferative activity are increased in cholesteatomas. It has also been shown that increased levels of TN, MMP-9-positive cells, and proliferative activity of the lesions, as well as decreased levels of apoptosis, can be linked to more aggressive clinical behavior of cholesteatomas. Our findings also indicate that TN and MMP-9 can be key molecules of bone destruction during cholesteatoma progression.

Variation patterns of two degradation enzyme systems in articular cartilage in different stages of osteoarthritis: regulation by dehydroepiandrosterone

BACKGROUND

Osteoarthritis (OA) is a multifactorial degenerative joint disease in which the cartilaginous matrix of the articular joint is destroyed in a continuous process. We evaluated mRNA levels of cysteine proteinases/cystatin C system and urokinase plasminogen activator/plasminogen activator inhibitor-1 (uPA/PAI-1) system in articular cartilage and regulation by dehydroepiandrosterone (DHEA) in different stages of osteoarthritis (OA).

METHODS

One hundred and eight rabbits underwent anterior cruciate ligament transection (ACLT) in the left knee, 54 received weekly intra-articular injections of DHEA (100 micromol/l) 0.3 ml 3 weeks after transaction as DHEA group. Thirty-six rabbits (18 from 2 groups respectively) were euthanized 6, 9, and 12 weeks after ACLT. All left knee joints were assessed by gross morphology and histology, meantime the gene expression from articular cartilage was analyzed.

RESULTS

Cathepsins and uPA gene increased significantly 6 weeks and reached peak in the 9th week, while declined to extremely low levels 12 weeks after ACLT. Cystatin C decreased accompanied by OA progression, while PAI-1 expressed in the same trend with uPA. Additionally, these 2 enzyme systems were markedly suppressed by DHEA 6 and 9 weeks after ACLT but not in the 12th week.

CONCLUSION

The variation of these 2 enzyme systems was closely related to the progression of OA, and could be regulated by DHEA especially in the early and medium stages of OA.

Inhibition of matrix metalloproteinases enhances in vitro repair of the meniscus

Damage or injury of the meniscus is associated with onset and progression of knee osteoarthritis (OA). The intrinsic repair capacity of the meniscus is inhibited by inflammatory cytokines, such as interleukin-1 (IL-1). Using an in vitro meniscal repair model system, we examined the hypothesis that inhibition of matrix metalloproteinases (MMPs) in the presence of IL-1 will enhance repair of meniscal lesions. Integrative repair of the meniscus was examined between two concentric explants cultured with IL-1 and various MMP inhibitors for 14 days. Throughout the culture period, we assessed total specific MMP activity in the media. At harvest, biomechanical testing to assess the strength of repair and histologic staining were performed. IL-1 decreased the shear strength of repair, as compared with control explants. In the presence of IL-1, the broad-spectrum MMP inhibitor GM 6001 decreased the MMP activity in the media, increased the shear strength of repair, and enhanced tissue repair in the interface. However, individual MMP inhibitors did not alter the shear strength of repair in either the presence or absence of IL-1. These findings suggest IL-1 may inhibit meniscal repair through upregulation of MMPs, but inhibition of multiple MMPs may be necessary to promote integrative meniscal repair.

Hepatic stellate cells promote hepatocyte engraftment in rat liver after prostaglandin-endoperoxide synthase inhibition

BACKGROUND & AIMS

Hepatic inflammation occurs immediately after cells are transplanted to the liver, but the mechanisms that underlie this process are not fully defined. We examined cyclooxygenase pathways that mediate hepatic inflammation through synthesis of prostaglandins, prostacyclins, thromboxanes, and other prostanoids following transplantation of hepatocytes.

METHODS

We transplanted F344 rat hepatocytes into syngeneic dipeptidyl peptidase IV-deficient F344 rats. Changes in cyclooxygenase pathways were analyzed, and specific pathways were blocked pharmacologically; the effects on cell engraftment and native liver cells were determined.

RESULTS

Transplantation of hepatocytes induced hepatic expression of prostaglandin-endoperoxide synthases 1 and 2, which catalyze production of prostaglandin H2, as well as the downstream factor thromboxane synthase, which produces thromboxane A2 (a regulator of vascular and platelet responses in inflammation). Transplanted hepatocytes were in proximity with liver cells that expressed prostaglandin-endoperoxide synthases. The number of engrafted hepatocytes increased in rats given naproxen or celecoxib before transplantation but not in rats given furegrelate (an inhibitor of thromboxane synthase) or clopodigrel (an antiplatelet drug). Naproxen and celecoxib did not prevent hepatic ischemia or activation of neutrophils, Kupffer cells, or inflammatory cytokines, but they did induce hepatic stellate cells to express cytoprotective genes, vascular endothelial growth factor and hepatocyte growth factor, and matrix-type metalloproteinases and tissue inhibitor of metalloproteinase-1, which regulate hepatic remodeling.

CONCLUSIONS

Activation of cyclooxygenase pathways interferes with engraftment of transplanted hepatocytes in the liver. Pharmacologic blockade of prostaglandin-endoperoxide synthases stimulated hepatic stellate cells and improved cell engraftment.