Osteoarthritis of the knee and hip. Part II: therapy with ibuprofen and a review of clinical trials

Neuro-Immunomodulatory Potential of Nanoenabled 4D Bioprinted Microtissue for Cartilage Tissue Engineering

Cartilage defects trigger post-traumatic inflammation, leading to a catabolic metabolism in chondrocytes and exacerbating cartilage degradation. Current treatments aim to relieve pain but fail to target the inflammatory process underlying osteoarthritis (OA) progression. Here, a human cartilage microtissue (HCM) nanoenabled with ibuprofen-loaded poly(lactic-co-glycolic acid) nanoparticles (ibu-PLGA NPs) is 4D-bioprinted to locally mitigate inflammation and impair nerve sprouting. Under an in vitro inflamed environment, the nanoenabled HCM exhibits chondroprotective potential by decreasing the interleukin (IL)1β and IL6 release, while sustaining extracellular matrix (ECM) production. In vivo, assessments utilizing the air pouch mouse model affirm the nanoenabled HCM non-immunogenicity. Nanoenabled HCM-derived secretomes do not elicit a systemic immune response and decrease locally the recruitment of mature dendritic cells and the secretion of multiple inflammatory mediators and matrix metalloproteinases when compared to inflamed HCM condition. Notably, the nanoenabled HCM secretome has no impact on the innervation profile of the skin above the pouch cavity, suggesting a potential to impede nerve growth. Overall, HCM nanoenabled with ibu-PLGA NPs emerges as a potent strategy to mitigate inflammation and protect ECM without triggering nerve growth, introducing an innovative and promising approach in the cartilage tissue engineering field.

Association of long-term use of non-steroidal anti-inflammatory drugs with knee osteoarthritis: a prospective multi-cohort study over 4-to-5 years

This study examines the long-term impact of non-steroidal anti-inflammatory drugs (NSAIDs) on the progression of symptoms and structural deterioration of the joint in knee osteoarthritis. The study analyzes data from 4197 participants (8394 knees) across the Osteoarthritis Initiative (OAI), Multicenter Osteoarthritis Study (MOST), and Cohort Hip and Cohort Knee (CHECK) over 4-to-5 years. Adjustments were made for major covariates. We focussed on binary outcomes to assess the presence or absence of significant changes. We found that, relative to non-users, individuals using NSAIDs long-term were significantly more likely to experience aggravated symptoms exceeding the minimally clinically important difference, specifically, pain (OR: 2.04, 95% CI: 1.66-2.49), disability (OR: 2.21, 95% CI: 1.74-2.80), and stiffness (OR: 1.58, 95% CI: 1.29-1.93). Long-term users also faced a higher probability than non-users of having total knee replacement (OR: 3.13, 95% CI: 2.08-4.70), although no significant difference between long-term users and non-users was observed for structural deterioration in the knee joint (OR: 1.25, 95% CI: 0.94-1.65). While acknowledging the limitations of this study due to its observational design and the potential for bidirectional causality, these findings suggest that long-term NSAID use could accelerate the progression to total knee replacement by markedly exacerbating symptoms.

Osteoarthritis

The clinical appearance and radiological pattern of osteoarthritis have been identified in the skeletons of dinosaurs some 50-70 million years old, and in Egyptian mummies, and in ancient skeletons in England. Osteoarthritis patterns of joint involvement, often referred to as primary osteoarthritis, can be seen in the hands, spinal facet joints, hips, knees and feet, but can also be termed secondary osteoarthritis when seen in any joint that has had trauma, sepsis, surgery or metabolic insult. The prevalence of osteoarthritis increases with age. The histology and pathophysiology both demonstrate an inflammatory process. While there have been studies of genetic predisposition, the basic cause of primary osteoarthritis has not been determined.

ADAM8 silencing suppresses the migration and invasion of fibroblast-like synoviocytes via FSCN1/MAPK cascade in osteoarthritis

OBJECTIVE

Osteoarthritis (OA) is a degenerative joint disease that affects elderly populations worldwide, causing pain and disability. Alteration of the fibroblast-like synoviocytes (FLSs) phenotype leads to an imbalance in the synovial inflammatory microenvironment, which accelerates the progression of OA. Despite this knowledge, the specific molecular mechanisms of the synovium that affect OA are still unclear.

METHODS

Both in vitro and in vivo experiments were undertaken to explore the role of ADAM8 playing in the synovial inflammatory of OA. A small interfering RNA (siRNA) was targeting ADAM8 to intervene. High-throughput sequencing was also used.

RESULTS

Our sequencing analysis revealed significant upregulation of the MAPK signaling cascade and ADAM8 gene expression in IL-1β-induced FLSs. The in vitro results demonstrated that ADAM8 blockade inhibited the invasion and migration of IL-1β-induced FLSs, while also suppressing the expression of related matrix metallomatrix proteinases (MMPs). Furthermore, our study revealed that inhibiting ADAM8 weakened the inflammatory protein secretion and MAPK signaling networks in FLSs. Mechanically, it revealed that inhibiting ADAM8 had a significant effect on the expression of migration-related signaling proteins, specifically FSCN1. When siADAM8 was combined with BDP-13176, a FSCN1 inhibitor, the migration and invasion of FLSs was further inhibited. These results suggest that FSCN1 is a crucial downstream factor of ADAM8 in regulating the biological phenotypes of FLSs. The in vivo experiments demonstrated that ADAM8 inhibition effectively reduced synoviocytes inflammation and alleviated the progression of OA in rats.

CONCLUSIONS

ADAM8 could be a promising therapeutic target for treating OA by targeting synovial inflammation.

Stigmasterol regulates microglial M1/M2 polarization via the TLR4/NF-κB pathway to alleviate neuropathic pain

(Switching from the microglial M1 phenotype to the M2 phenotype is a promising therapeutic strategy for neuropathic pain (NP). This study aimed to investigate the potential use of stigmasterol for treating NP. In animal experiments, 32 male Sprague-Dawley rats were randomly divided into the sham operation group, chronic constriction injury (CCI) group, CCI + ibuprofen group, and CCI + stigmasterol group. We performed behavioral tests, enzyme-linked immunosorbent assay, hematoxylin-esoin staining (H&E) staining and immunohistochemistry, immunofluorescence, and Western blotting. In cell experiments, we performed flow cytometry, immunofluorescence, Western blotting, and qRT-PCR. Stigmasterol reduced thermal and mechanical hyperalgesia and serum IL-1β and IL-8 levels and increased serum IL-4 and TGF-β levels in CCI rats. Stigmasterol reduced IL-1β, COX-2, and TLR4 expression in the right sciatic nerve and IL-1β expression in the spinal cord. Stigmasterol reduced the expression of Iba-1, TLR4, MyD88, pNF-κB, pP38 MAPK, pJNK, pERK, COX-2, IL-1β, and CD32 in the spinal cord of CCI rats while increasing the expression of IL-10 and CD206. Stigmasterol decreased M1 polarization markers and increased M2 polarization markers in lipopolysaccharide (LPS)-induced microglia and decreased the expression of Iba-1, TLR4, MyD88, pNF-κB, pP38 MAPK, pJNK, pERK, iNOS, COX-2, and IL-1β in LPS-treated microglia while increasing the expression of Arg-1 and IL-10. Stigmasterol regulates microglial M1/M2 polarization via the TLR4/NF-κB pathway to alleviate NP.

Consensus Guidelines on Interventional Therapies for Knee Pain (STEP Guidelines) from the American Society of Pain and Neuroscience

Knee pain is second only to the back as the most commonly reported area of pain in the human body. With an overall prevalence of 46.2%, its impact on disability, lost productivity, and cost on healthcare cannot be overlooked. Due to the pervasiveness of knee pain in the general population, there are no shortages of treatment options available for addressing the symptoms. Ranging from physical therapy and pharmacologic agents to interventional pain procedures to surgical options, practitioners have a wide array of options to choose from - unfortunately, there is no consensus on which treatments are "better" and when they should be offered in comparison to others. While it is generally accepted that less invasive treatments should be offered before more invasive ones, there is a lack of agreement on the order in which the less invasive are to be presented. In an effort to standardize the treatment of this extremely prevalent pathology, the authors present an all-encompassing set of guidelines on the treatment of knee pain based on an extensive literature search and data grading for each of the available alternative that will allow practitioners the ability to compare and contrast each option.

A systematic review and meta-analysis of the effect of phonophoresis on patients with knee osteoarthritis

This systematic review and meta-analysis investigated the effect of phonophoresis when various gel types were used. Medline (using PubMed), EMBASE, and Cochrane Central Register of Controlled Trials (CENTRAL) were used to search for relevant studies from the date of their inception to June 28, 2021. We included studies that were randomized controlled trials (RCTs), included patients with a diagnosis of knee osteoarthritis, included treatment with either phonophoresis or therapeutic ultrasound with placebo gel, and reported clinical and functional outcomes. Continuous variables are expressed as standardized mean differences (SMDs) with 95% confidence intervals (CIs). Statistical analysis was performed using RevMan 5.3 software. We initially retrieved 2176 studies and finally analyzed nine RCTs including 423 patients. The intervention group significantly outperformed the control group in pain scores with NSAID gel (SMD = - 0.53, 95% CI [- 1.02, - 0.05], I2 = 73%) and in the Western Ontario and McMaster Universities Arthritis Index (WOMAC) function score with corticosteroid gel (SMD = - 0.96, 95% CI [- 1.47, - 0.44], I2 = 20%). Phonophoresis alleviated pain and improved functional performance. Because of some limitations of this study, additional high-quality, large-scale RCTs are required to confirm the benefits.

The Effects of Antioxidant Supplements on the Inflammatory Gene Expression of Osteoarthritis-Like Chondrocytes

Osteoarthritis patients often experience pain and inflammation in joints. To understand whether antioxidant supplements could reduce inflammation and could potentially be applied for osteoarthritis treatment, vitamin E and resveratrol were investigated in this study. Hydrogen peroxide was used for inducing inflammation in porcine chondrocytes, and the lumen density was measured for the level of oxygen-derived free radicals. In total, 5, 50, 100, and 200 μM of vitamin E and resveratrol were analyzed for cell viability and the effect of lumen density. In addition, the expressions of IL-1β, TNF-α, MMP-1, MMP-13, and COL2A1 were investigated when treating chondrocytes with 100 μM vitamin E, 5 μM resveratrol, or their combination before or after hydrogen peroxide induction. Inducing chondrocytes with hydrogen peroxide for 30 min increased the level of lumen density sufficiently and stimulated the expression of inflammatory genes. All the concentrations of vitamin E and resveratrol showed good cell viability. Single treatment with either vitamin E or resveratrol reduced inflammatory gene expression, and combined treatment increased the expression of collagen type II. The results suggested that post-treatment with both vitamin E and resveratrol has a better effect on the reduction in inflammation in osteoarthritis-like chondrocytes.

Co-Administered Low Doses Of Ibuprofen And Dexamethasone Produce Synergistic Antinociceptive Effects On Neuropathic Mechanical Allodynia In Rats

Background

The traditional analgesics used to treat neuropathic pain such as anticonvulsants, opioids, and nonsteroidal anti-inflammatory drugs (NSAIDs) lack efficacy and/or carry unpleasant side effects. The present study aimed to investigate the synergistic antinociceptive effects of co-administered low doses of ibuprofen and dexamethasone in rats with trigeminal neuropathic pain.

Materials and methods

A Sprague-Dawley rat model for trigeminal neuropathic pain was produced using mal-positioned dental implants. The left mandibular second molar was extracted under anesthesia and replaced with a miniature dental implant to induce injury to the inferior alveolar nerve.

Results

Monotherapy with intraperitoneal injection of high-dose ibuprofen (30 mg/kg) or dexamethasone (10 mg/kg) but not low-dose ibuprofen (1, 5, 10 mg/kg) or dexamethasone (0.01, 1 mg/kg) attenuated the neuropathic mechanical allodynia in the rats with inferior alveolar nerve injury. We examined the synergistic antinociceptive effects of co-administered ibuprofen (5 mg/kg) and dexamethasone (0.01, 0.1, 1 mg/kg). The early co-administration of ibuprofen (5 mg/kg) with dexamethasone (0.1, 1 mg/kg) on postoperative days (POD) 1–3 significantly inhibited mechanical allodynia before the pain had been established. We also observed the synergistic antinociceptive effects of the same doses the combined treatment on mechanical allodynia on POD 7–9, when the pain had already been established. The attenuation of c-fos immuno-positive cells in the ipsilateral trigeminal subnucleus caudalis after the intraperitoneal co-administration of ibuprofen (5 mg/kg) with dexamethasone (1 mg/kg) confirmed these synergistic antinociceptive effects. Moreover, the magnitude of the effects of this co-administration was comparable with that of gabapentin both before and after the pain had been established.

Conclusion

These results suggest that a combination of ibuprofen and dexamethasone at low doses is an alternative therapeutic strategy for neuropathic pain and provide a rationale for the use of such drug combinations in patients who are unable to tolerate high-dose monotherapy.

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.

Adenosine-Functionalized Biodegradable PLA-b-PEG Nanoparticles Ameliorate Osteoarthritis in Rats

Short biologic half-lives limit the therapeutic utility of many small molecules. One approach to extending the half-life of pharmacologically active small molecules is conjugation to less degradable nanoparticles; here we report the synthesis and activity of six targeted polymeric (PEG-b-PLA) nanoparticles for use as adenosine receptor agonists. Using click chemistry, PLA-b-PEG400-N₃ and PLA-b-PEG2000 block copolymers were bound to adenosine at the 3′,4′-OH, 5′-OH, and 6-NH₂ positions with an acetylene group. Activity of the conjugates as adenosine receptor ligands was tested by their capacity to stimulate cAMP increases in RAW264.7 murine macrophage cells. Only adenosine-conjugated nanoparticles (A-3′,4′-OH-TPN2), in which PEG2000 was bound to adenosine on the 3′,4′ hydroxyl groups, stimulated cAMP increases and these increases were blocked by selective antagonists of both adenosine A2A and A2B receptors, consistent with ligation of these receptors. Adenosine nanoparticles were tested in vivo in a rat model of post-traumatic osteoarthritis; intra-articular injection of adenosine nanoparticles prevented the development of osteoarthritis in this model. These studies suggest that attachment of adenosine to biodegradable nanoparticles provides a novel approach to achieving prolonged therapeutic effects.

2017 update of the Turkish League Against Rheumatism (TLAR) evidence-based recommendations for the management of knee osteoarthritis

In a Turkish League Against Rheumatism (TLAR) project, evidence-based recommendations for the management of knee osteoarthritis (OA) was developed for the first time in our country in 2012 (TLAR-2012). In accordance with developing medical knowledge and scientific evidence, recommendations were updated. The committee was composed of 22 physical medicine and rehabilitation specialists (4 have rheumatology subspeciality also) and an orthopaedic surgeon. Systematic literature search were applied on Pubmed, Embase, Cochrane and Turkish Medical Index for the dates between January the 1st 2012 and January the 29th of 2015. The articles were assessed for quality and classified according to hierarchy for the level of evidence, and the selected ones sent to committee members electronically. They were asked to develop new recommendations. In the meeting in 2015, the format of the recommendations was decided to be patient-based and considering the grade and the severity of the disease. By the discussion of the each item under the light of new evidences, the final recommendations were developed. Each item was voted electronically on a 10-cm visual analogue scale (VAS) and the strength of recommendation (SoR) was calculated. In the light of evidences, totally 11 titles of recommendations were developed; the first 7 were applicable to each patient in every stages of the disease, remaining were for defined specific clinical situations. The mean SoR value of the recommendations was between 7.44 and 9.93. TLAR-2012 recommendations were updated in a new format. We think that, present recommendations will be beneficial for the physicians who manage, as well as the patients who suffer from the disease.

Long term use of analgesics and risk of osteoarthritis progressions and knee replacement: propensity score matched cohort analysis of data from the Osteoarthritis Initiative

OBJECTIVES

To determine the association between the long-term use of analgesics and progression of osteoarthritis (OA) as evidenced by up to 3-years follow-up worsening of radiographic Kellgren-Lawrence (KL) grade and incidence of knee replacement (KR).

DESIGN

Using nearest neighbor matching of the propensity scores with caliper in the Osteoarthritis Initiative (OAI) cohort, 173 index (Analgesic +) and 173 referent (Analgesic -) subjects were included. Analgesic + and - subjects had analgesics in all and none of their visits, respectively. Analgesic + and - subjects were balanced in their demographics, baseline, first, second and third year body mass index (BMI), Western Ontario and McMaster (WOMAC) total score, Physical and Mental health summary scales (SF-12), Physical Activity Scale for the Elderly (PASE) and Charleston Comorbidity Scale. Analgesic + and - subjects were also matched for baseline radiographic KL grade. Interval increase in the KL grade and incidence of KR were defined as the outcome.

RESULTS

Included subjects had average 6.5 years of follow-up. By the third year, 44 subjects had an interval increase in the KL grade; 29 in Analgesic + and 15 among Analgesic - subjects (P = 0.024). By the eighth-year, 41 subjects had their first KR; 29 in Analgesic + and 12 among Analgesic - subjects (P = 0.005). Hazard Ratio (HR) of OA progression and KR for Analgesic + subjects was 1.91 (1.02-3.57) and 2.57 (1.31-5.04), respectively.

CONCLUSIONS

Long-term use of analgesics may be associated with radiographic progression of knee OA and increased risk of future KR.

Benefits of antioxidant supplements for knee osteoarthritis: rationale and reality

Arthritis causes disability due to pain and inflammation in joints. There are many forms of arthritis, one of which is osteoarthritis whose prevalence increases with age. It occurs in various joints including hip, knee and hand with knee osteoarthritis being more prevalent. There is no cure for it. The management strategies include exercise, glucosamine plus chondroitin sulfate and NSAIDs. In vitro and animal studies provide a rationale for the use of antioxidant supplements for its management. This review assesses the reality of the benefits of antioxidant supplements in the management of knee osteoarthritis. Several difficulties were encountered in examining this issue: poorly conducted studies, a lack of uniformity in disease definition and diagnosis, and muddling of conclusions from attempts to isolate the efficacious molecules. The antioxidant supplements with most evidence for benefit for pain relief and function in knee osteoarthritis were based on curcumin and avocado-soya bean unsaponifiables. Boswellia and some herbs used in Ayurvedic and Chinese medicine may also be useful. The benefits of cuisines with the appropriate antioxidants should be assessed because they may be more economical and easier to incorporate into the lifestyle.

Effects of prescription nonsteroidal antiinflammatory drugs on symptoms and disease progression among patients with knee osteoarthritis

OBJECTIVE

The effect of short-term and long-term use of nonsteroidal antiinflammatory drugs (NSAIDs) on structural change is equivocal. The aim of this study was to estimate the extent to which short- and long-term use of prescription NSAIDs relieve symptoms and delay structural progression among patients with radiographically confirmed osteoarthritis (OA) of the knee.

METHODS

We applied a new-user design among participants with confirmed OA not reporting NSAID use at the time of enrollment in the Osteoarthritis Initiative. Participants were evaluated for changes in the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) subscales (n = 1,846) and joint space width was measured using serial radiographs and a customized software tool (n = 1,116) over 4 years. We used marginal structural modeling to estimate the effect of NSAIDs.

RESULTS

Compared to participants who never reported prescription NSAID use, those reporting use at 1 or 2 assessments had no clinically important changes, but those reporting prescription NSAID use at all 3 assessments had, on average, 0.88 point improvement over the followup period (95% confidence interval [95% CI] -0.46 to 2.22) in pain, 0.72 point improvement (95% CI -0.12 to 1.56) in stiffness, and 4.27 points improvement (95% CI -0.31 to 8.84) in function. The average change in joint space width was 0.28 mm less among those reporting NSAID use at 3 assessments relative to nonusers (95% CI -0.06 to 0.62). Recent NSAID use findings were not clinically or statistically significant.

CONCLUSION

Long-term, but not short-term, NSAID use was associated with an a priori-defined minimally important clinical change in stiffness, physical function, and joint space width, but not pain. While showing modest clinical importance, the estimates did not reach statistical significance.

Use of ibuprofen sustained release for treating osteoarthritic pain: findings from 15 general medical practices in Egypt

Purpose

Ibuprofen sustained release (SR) has been shown to provide effective symptomatic pain relief in chronic arthritic conditions such as osteoarthritis in European and US patient populations. Few studies have been conducted in other patient populations. A 4-week prospective multicenter open-label observational study was designed to explore and describe the combined effect of ibuprofen SR and standard medical care in patients suffering from osteoarthritis in 15 general medical practices in Egypt.

Patients and methods

In total, 519 patients were prescribed ibuprofen SR 2 ×800 mg once daily for 4 weeks.

Results

Ibuprofen SR combined with standard medical care significantly improved day and night pain, with 99.4% of the patients reporting improvement. The treatment reduced the symptom severity of joint tenderness/stiffness and the duration of morning stiffness, and allowed more patients to carry out normal activities. Overall compliance with the prescribed ibuprofen SR regimen was 98.6%. Ibuprofen SR was generally well tolerated with no serious adverse events reported during the study. There was no increase in blood pressure or heart rate.

Conclusion

The combined treatment provided effective relief of pain in patients with osteoarthritis in a large real-life general medical practice setting in Egypt. Owing to its convenient once-daily dosing regimen, ibuprofen SR may enhance patient compliance.

Ibuprofen: from invention to an OTC therapeutic mainstay

The discovery of ibuprofen's anti-inflammatory activity by Dr (now Professor) Stewart Adams and colleagues (Boots Pure Chemical Company Ltd, Nottingham, UK) 50 years ago represented a milestone in the development of anti-inflammatory analgesics. Subsequent clinical studies were the basis for ibuprofen being widely accepted for treating painful conditions at high anti-rheumatic doses (≤ 2400 mg/d), with lower doses (≤ 1200 mg/d for ≤ 10 days) for mild-moderate acute pain (e.g. dental pain, headache, dysmenorrhoea, respiratory symptoms and acute injury). The early observations have since been verified in studies comparing ibuprofen with newer cyclo-oxygenase-2 selective inhibitors ('coxibs'), paracetamol and other non-steroidal anti-inflammatory drugs (NSAIDs). The use of the low-dose, non-prescription, over-the-counter (OTC) drug was based on marketing approval in 1983 (UK) and 1984 (USA); and it is now available in over 80 countries. The relative safety of OTC ibuprofen has been supported by large-scale controlled studies. It has the same low gastro-intestinal (GI) effects as paracetamol (acetaminophen) and fewer GI effects than aspirin. Ibuprofen is a racemate. Its physicochemical properties and the short plasma-elimination half-life of the R(-) isomer, together with its limited ability to inhibit cyclo-oxygenase-1 (COX-1) and thus prostaglandin (PG) synthesis, compared with that of S(+)-ibuprofen, are responsible for the relatively low GI toxicity. The R(-) isomer is then converted in the body to the S(+) isomer after absorption in the GI tract. Ex vivo inhibition of COX-1 (thromboxane A(2)) and COX-2 (PGE(2)) at the plasma concentrations of S(+)-ibuprofen corresponding to those found in the plasma following ingestion of 400 mg ibuprofen in dental and other inflammatory pain models provides evidence of the anti-inflammatory mechanism at OTC dosages. R(-)-ibuprofen has effects on leucocytes, suggesting that ibuprofen has anti-leucocyte effects, which underlie its anti-inflammatory actions. Future developments include novel gastro-tolerant forms for 'at risk' patients, and uses in the prevention of neuro-inflammatory states and cancers.

Chronic ibuprofen administration reduces neuropathic pain but does not exert neuroprotection after spinal cord injury in adult rats

Ibuprofen is commonly used as an anti-inflammatory analgesic drug, although it is not amongst the first-line treatments for neuropathic pain. Its main effects are mediated by non-specific inhibition of COX enzymes, but it also exerts some COX-independent effects, such as the inhibition of RhoA signaling and the modulation of glial activity. These effects have boosted the use of ibuprofen as a tool to promote axonal regeneration and to increase functional recovery after neural injuries, although with controversial results showing positive and negative outcomes of ibuprofen treatment in several experimental models. We have evaluated the effects of ibuprofen administered at 60 mg/kg twice a day to rats subjected to a mild spinal cord contusion. Our results indicate that ibuprofen ameliorates mechanical hyperalgesia in rats by reducing central hyperexcitability, but failed to produce improvements in the recovery of locomotion. Despite an early effect on reducing microglial reactivity, the ibuprofen treatment did not provide histological evidence of neuroprotection; indeed the volume of cord tissue spared rostral to the lesion was decreased in ibuprofen treated rats. In summary, the early modulation of neuroinflammation produced by the administration of ibuprofen seems to eventually lead to a worse resolution of detrimental events occurring in the secondary injury phase, but also to reduce the development of neuropathic pain.

In vitro evaluation of S-(+)-ibuprofen as drug candidate for intra-articular drug delivery system

Intra-articular drug delivery systems (DDSs) are envisaged as interesting alternative to locally release non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen to reduce pain in patients with osteoarthritis. The present study examines the efficacy of S-(+)-ibuprofen on cartilage degradation as drug candidate for DDS loading. Humeral cartilage and joint capsule explants were collected from healthy sheep shoulder joints and they were cultured in mono- or in co-culture for 13 days with LPS in combination with S-(+)-ibuprofen at 50 µM and 1 mM. S-(+)-ibuprofen (50 µM) blocked prostaglandins production in LPS-activated explants but did not reduce cartilage degradation. By contrast, 1 mM S-(+)-ibuprofen treatment of cartilage explants reduced nitric oxide synthesis by 51% (p = 0.0072), proteoglycans degradation by 35% (p = 0.0114) and expression of serum amyloid protein - the main protein induced upon LPS challenge - by 44% (p < 0.0001). On contrary, in presence of synovial membrane, the protective effects of S-(+)-ibuprofen on cartilage damages were significantly diminished. At 1mM, S-(+)-ibuprofen reduced the cell lysis during culture of cartilage and joint capsule either in mono- or in co-culture. This study performed on sheep explants shows that 1 mM S-(+)-ibuprofen inhibited cartilage degradation via a mechanism independent of cyclooxygenase inhibition. Reduction of prostaglandins synthesis at 50 µM in all treatment groups and reduction of cartilage degradation observed at 1 mM suggest that S-(+)-ibuprofen could be considered as a promising drug candidate for the loading of intra-articular DDS.