Renin-angiotensin system in osteoarthritis: A new potential therapy

Advances in the pathology and treatment of osteoarthritis

BACKGROUND

Osteoarthritis (OA), a widespread degenerative joint disease, predominantly affects individuals from middle age onwards, exhibiting non-inflammatory characteristics. OA leads to the gradual deterioration of articular cartilage and subchondral bone, causing pain and reduced mobility. The risk of OA increases with age, making it a critical health concern for seniors. Despite significant research efforts and various therapeutic approaches, the precise causes of OA remain unclear.

AIM OF REVIEW

This paper provides a thorough examination of OA characteristics, pathogenic mechanisms at various levels, and personalized treatment strategies for different OA stages. The review aims to enhance understanding of disease mechanisms and establish a theoretical framework for developing more effective therapeutic interventions.

KEY SCIENTIFIC CONCEPTS OF REVIEW

This review systematically examines OA through multiple perspectives, integrating current knowledge of clinical presentation, pathological mechanisms, and associated signaling pathways. It assesses diagnostic methods and reviews both pharmacological and surgical treatments for OA, as well as emerging tissue engineering approaches to manage the disease. While therapeutic strategies such as exercise, anti-inflammatory drugs, and surgical interventions are employed to manage symptoms and modify joint structure, none have been able to effectively halt OA's advancement or achieve long-lasting symptom relief. Tissue engineering strategies, such as cell-seeded scaffolds, supportive matrices, and growth factor delivery, have emerged as promising approaches for cartilage repair and OA treatment. To combat the debilitating effects of OA, it is crucial to investigate the molecular basis of its pathogenesis and seek out innovative therapeutic targets for more potent preventive and treatment strategies.

Interaction between angiotensin-converting enzyme gene rs4343 polymorphism, environment factors, and angiotensin II level on susceptibility to knee osteoarthritis

OBJECTIVES

Osteoarthritis (OA) is a complex multifactorial disease. The association of knee OA risk with ACE gene rs4343 polymorphism, gene environment synergistic effect, and angiotensin II serum level has not been previously examined. Therefore, we investigate the ACE gene rs4343 polymorphism in knee OA, and its association with severity of knee OA, and angiotensin II serum level.

METHODS

Using a case-control design, we recruited 200 subjects (100 cases and 100 controls) and all were subjected to genotyping of rs4343 SNP by real-time polymerase chain reaction and assay of serum angiotensin II level by ELISA.

RESULTS

G containing genotypes (AG and GG) and G allele frequencies of the ACE rs4343 polymorphism were significantly higher in the case group than that in the control group. There was significant association between ACE rs4343 genotypes and risk of knee OA under the following genetic inheritance models: GG vs. AA (P=0.003), AA vs. GG/AG (P=0.014), AG/AA vs. GG (P=0.037), and G vs. A (P<0.001). Stratified analyses showed ACE rs4343 polymorphism was evidently associated with a significantly increased risk of knee OA among those had BMI≥25% (adjusted OR=3.016; 95% CI 1.052-8.648; P=0.040). Additionally, knee OA patients with GG genotype had greater knee specific WOMAC index, Kellgren score, and serum angiotensin II level than those with AA or GA genotypes.

CONCLUSION

The investigated polymorphism in the ACE gene rs4343 may reflect the risk and severity of knee OA in the Egyptian population, particularly with the GG genotype. The interaction between ACE gene rs4343 polymorphism and obesity further increased the risk of knee OA. Moreover, the higher angiotensin II level may be involved in the pathogenesis of knee OA.

Aging and "Age-Related" Diseases - What Is the Relation?

The study explores the intricate relationship between aging and the development of noncommunicable diseases [NCDs], focusing on whether these diseases are inevitable consequences of aging or primarily driven by lifestyle factors. By examining epidemiological data, particularly from hunter-gatherer societies, the study highlights that many NCDs prevalent in modern populations are rare in these societies, suggesting a significant influence of lifestyle choices. It delves into the mechanisms through which poor diet, smoking, and other lifestyle factors contribute to systemic physiological imbalances, characterized by oxidative stress, insulin resistance and hyperinsulinemia, and dysregulation of the sympathetic nervous system, the renin-angiotensin-aldosterone system, and the immune system. The interplay between this pattern and individual factors such as genetic susceptibility, biological variability, epigenetic changes and the microbiome is proposed to play a crucial role in the development of a range of age-related NCDs. Modified biomolecules such as oxysterols and advanced glycation end products also contribute to their development. Specific diseases such as benign prostatic hyperplasia, Parkinson's disease, glaucoma and osteoarthritis are analyzed to illustrate these mechanisms. The study concludes that while aging contributes to the risk of NCDs, lifestyle factors play a crucial role, offering potential avenues for prevention and intervention through healthier living practices. One possible approach could be to try to restore the physiological balance, e.g. through dietary measures [e.g. Mediterranean diet, Okinawan diet or Paleolithic diet] in conjunction with [a combination of] pharmacological interventions and other lifestyle changes.

Association between angiotensin-converting enzyme (ACE) gene I/D polymorphism with the risk of knee OA: A systematic review, meta-analysis, and meta-regression

Background

Previous studies have linked genetics to knee osteoarthritis. Angiotensin-converting enzyme (ACE) gene I/D polymorphism may cause OA. However, evidence remains inconsistent. This study examines knee OA risk and ACE gene I/D polymorphism.

Methods

We explored Europe PMC, Medline, Scopus, and Cochrane Library using keywords. Three assessment bias factors were assessed using the Newcastle-Ottawa Scale (NOS). Criteria for inclusion: (1) Split the study population into knee OA patients and healthy controls; (2) Analysed the ACE gene I/D polymorphism; (3) Case-control or cross-sectional surveys. Studies with non-knee OA, incomplete data, and no full-text were excluded. The odds ratio (OR) and 95% confidence intervals (95% CI) were calculated using random-effect models.

Results

A total of 6 case-control studies consist of 1,226 patients with knee OA and 1,145 healthy subjects as controls were included. Our pooled analysis revealed that a significant association between ACE gene I/D polymorphism and risk of knee OA was only seen in the dominant (DD + ID vs. II) [OR 1.69 (95% CI 1.14 - 2.50), p = 0.009, I2 = 72%], and ID vs. II [OR 1.37 (95% CI 1.01- 1.86), p = 0.04, I2 = 43%] genotype models. Other genotype models, including recessive (DD vs. ID + II), alleles (D vs. I), DD vs. ID, and DD vs. II models did not show a significant association with knee OA risk. Further regression analysis revealed that ethnicity and sex may influence those relationships in several genotype models.

Conclusions

Dominant and ID vs. II ACE gene I/D polymorphism models increased knee OA risk significantly. More research with larger samples and different ethnic groups is needed to confirm our findings. After ethnicity subgroup analysis, some genetic models in our study showed significant heterogeneities, and most studies are from Asian countries with Asian populations, with little evidence on Arabs.

Hyaluronic acid/diminazene aceturate combination ameliorates osteoarthritic anomalies in a rodent model: a role of the ACE2/Ang1-7/MasR axis

The implication of the tissue-localized renin-angiotensin system (RAS) in the pathogenesis of osteoarthritis (OA) has been documented in the last decades. A combination of intraarticular (IA) corticosteroid and hyaluronic acid (HYAL) is approved for pain relief in patients with mild to moderate OA. Combining HYAL with an activator of angiotensin-converting enzyme 2, diminazen aceturate (DIZE), was evaluated in this study for its therapeutic potential. Monosodium iodoacetate was used to induce OA. The effects of daily administration of DIZE versus once-per-week IA injection of HYAL and a combination of both drugs for 21 days on OA deformities in rats' knees were observed. Evaluation of motor activities, pain, and inflammatory response was done using rotarod, knee bend, and knee swelling tests. RAS components, inflammatory biomarkers, and oxidative stress mediators were measured in the knee joint. X-ray radiological examination and histopathological investigations were used to assess joint degeneration and regeneration. Levels of both inflammatory and oxidative markers in knee joint homogenate of OA rats rose, and these increments were mostly improved by the three therapies with a more prominent effect of the drug combination, an effect that was also reflected in the behavioral tests. RAS markers have shown better responsiveness to the combination therapy over both drugs individually, showing a pronounced increase in the angiotensin 1-7 amount. Both radiological and histopathology investigations came to confirm the biochemical results, nominating a combination of HYAL and DIZE as a possible therapeutic option for OA.

Diminazene aceturate or losartan ameliorates the functional, radiological and histopathological alterations in knee osteoarthritis rodent model: repurposing of the ACE2/Ang1-7/MasR cascade

PURPOSE

Current therapies for osteoarthritis (OA) are limited to analgesics and anti-inflammatory drugs. Considering the importance of oxidative stress and inflammatory mediators in OA etiology, we tested the hypothesis that targeting the renin-angiotensin-aldosterone system (RAAS) can improve OA anomalies. Diminazene (DIZE), an activator of angiotensin-converting enzyme 2 and the angiotensin 2 type-1 receptor blocker losartan (LOS) were used for this purpose.

METHODS

OA was induced by a single intra-articular injection of monosodium iodoacetate. The effects of exposure to DIZE or LOS for 21 days on OA anomalies in rats' knees were investigated. Evaluation of motor function, nociception, and inflammatory response was done using rotarod, knee bend and knee swelling tests. Markers of knee joint inflammation, and cellular oxidation in addition to the RAAS biomarkers, were assessed in knee tissues, along with radiological and histopathological investigations.

RESULTS

Elevations in inflammatory and oxidative markers in knee tissues of OA rats were mostly improved by the two therapeutic drugs. Such effect was also reflected in the rotarod, knee bend and knee swelling tests. Treatment with DIZE has shown a more prominent effect than LOS in controlling OA-associated inflammation and cellular oxidation. Markers of RAAS have also shown better responsiveness to DIZE over LOS.

CONCLUSIONS

DIZE has shown a prominent increase in the angiotensin 1-7 amount, highlighting the involvement of the signaling pathway in the immunomodulatory effect. The radiological and histopathology examination came to confirm the outcome of biochemical markers, nominating diminazene aceturate as a possible therapeutic option for OA.

The effects of losartan or angiotensin II receptor antagonists on cartilage: a systematic review

OBJECTIVE

The aim of this study is to analyze the latest evidence on the effects of losartan or Ang II receptor antagonists on cartilage repair, with a focus on their clinical relevance.

DESIGN

The PubMed, Embase, and Cochrane Library databases were searched up to November 12th 2021 to evaluate the effects of losartan or Ang II receptor antagonists on cartilage repair in in vitro studies and in vivo animal studies. Study design, sample characteristics, treatment type, duration, and outcomes were analyzed. The risk of bias and the quality of the eligible studies were assessed using the Systematic Review Centre for Laboratory Animal Experimentation (SYRCLE) risk of bias assessment tool and Collaborative Approach to Meta-Analysis and Review of Animal Data from Experimental Studies (CAMARADES).

RESULTS

A total of 12 studies were included in this systematic review. Of the 12 eligible studies, two studies were in vitro human studies, three studies were in vitro animal studies, one study was an in vitro human and animal study, and six studies were in vivo animal studies. The risk bias and quality assessments were predominantly classified as moderate. Since meta-analysis was difficult due to differences in treatment type, dosage, route of administration, and method of outcome assessment among the eligible studies, qualitative evaluation was conducted for each study.

CONCLUSIONS

Both in vitro and in vivo studies provide evidence to demonstrate beneficial effects of Ang II receptor antagonists on osteoarthritis and cartilage defect models across animal species.

Genome-wide association meta-analysis of knee and hip osteoarthritis uncovers genetic differences between patients treated with joint replacement and patients without joint replacement

OBJECTIVES

Osteoarthritis is a common and severe, multifactorial disease with a well-established genetic component. However, little is known about how genetics affect disease progression, and thereby the need for joint placement. Therefore, we aimed to investigate whether the genetic associations of knee and hip osteoarthritis differ between patients treated with joint replacement and patients without joint replacement.

METHODS

We included knee and hip osteoarthritis cases along with healthy controls, altogether counting >700 000 individuals. The cases were divided into two groups based on joint replacement status (surgical vs non-surgical) and included in four genome-wide association meta-analyses: surgical knee osteoarthritis (N = 22 525), non-surgical knee osteoarthritis (N = 38 626), surgical hip osteoarthritis (N = 20 221) and non-surgical hip osteoarthritis (N = 17 847). In addition, we tested for genetic correlation between the osteoarthritis groups and the pain phenotypes intervertebral disc disorder, dorsalgia, fibromyalgia, migraine and joint pain.

RESULTS

We identified 52 sequence variants associated with knee osteoarthritis (surgical: 17, non-surgical: 3) or hip osteoarthritis (surgical: 34, non-surgical: 1). For the surgical phenotypes, we identified 10 novel variants, including genes involved in autophagy (rs2447606 in ATG7) and mechanotransduction (rs202127176 in PIEZO1). One variant, rs13107325 in SLC39A8, associated more strongly with non-surgical knee osteoarthritis than surgical knee osteoarthritis. For all other variants, significance and effect sizes were higher for the surgical phenotypes. In contrast, genetic correlations with pain phenotypes tended to be stronger in the non-surgical groups.

CONCLUSIONS

Our results indicate differences in genetic associations between knee and hip osteoarthritis depending on joint replacement status.

Effect of cell receptors in the pathogenesis of osteoarthritis: Current insights

Osteoarthritis (OA) is a chronic arthritic disease characterized by cartilage degradation, synovial inflammation, and subchondral bone lesions. The studies on the pathogenesis of OA are complex and diverse. The roles of receptors signaling in chondrocyte anabolism, inflammatory factors expression of synovial fibroblast, and angiogenesis in subchondral bone are particularly important for exploring the pathological mechanism of OA and clinical diagnosis and treatment. By reviewing the relevant literature, this article elaborates on the abnormal expression of receptors and the signaling transduction pathways from different pathological changes of OA anatomical components, aiming to provide new research ideas and clinical therapeutic value for OA pathogenesis.

Targeting inflammation and redox perturbations by lisinopril mitigates Freund's adjuvant-induced arthritis in rats: role of JAK-2/STAT-3/RANKL axis, MMPs, and VEGF

BACKGROUND

Cardiovascular disorders are major complications of rheumatoid arthritis (RA). Hence, finding effective agents that can target RA progression and its cardiovascular consequences is demanding. The present work aimed to explore the potential of lisinopril, an angiotensin-converting enzyme inhibitor, to mitigate adjuvant's-induced arthritis with emphasis on the pro-inflammatory signals, articular degradation cues, and angiogenesis alongside JAK-2/STAT-3 and Nrf2/HO-1 pathways.

METHODS

Lisinopril (10 mg/kg/day) was administered by oral gavage for 3 weeks and the target signals were examined by biochemical assays, ELISA, histopathology, immunoblotting, and immunohistochemistry.

RESULTS

Lisinopril attenuated the progression of arthritis as proven by lowering paw edema, arthritic index, and gait scores alongside diminishing the immune-cell infiltration/aberrant histopathology in the dorsal pouch lining. These favorable actions were associated with curtailing the production of inflammatory cytokines (TNF-α, IL-6, IL-1β, and IL-17) and the pro-inflammatory angiotensin II alongside upregulating the anti-inflammatory angiotensin-(1-7) in the hind paw of arthritic rats. At the molecular level, lisinopril inhibited the upstream JAK-2/STAT-3 pathway by downregulating the protein expression of p-JAK-2/total JAK-2 and p-STAT-3/total STAT-3 ratio and the nuclear levels of NF-κBp65. Meanwhile, lisinopril curbed the downstream cartilage degradation signals matrix metalloproteinases (MMP-3 and MMP-9) and the bone erosion cue RANKL. Equally important, the protein expression of the angiogenesis signal VEGF was downregulated in the hind paw/dorsal lining. With respect to oxidative stress, lisinopril suppressed the paw lipid peroxides and boosted GSH and Nrf-2/HO-1 pathway.

CONCLUSION

Lisinopril attenuated adjuvant-induced arthritis via inhibition of inflammation, articular degradation cues, and angiogenesis.

Pleiotropic Effects of Simvastatin and Losartan in Preclinical Models of Post-Traumatic Elbow Contracture

Elbow trauma can lead to post-traumatic joint contracture (PTJC), which is characterized by loss of motion associated with capsule/ligament fibrosis and cartilage damage. Unfortunately, current therapies are often unsuccessful or cause complications. This study aimed to determine the effects of prophylactically administered simvastatin (SV) and losartan (LS) in two preclinical models of elbow PTJC: an in vivo elbow-specific rat injury model and an in vitro collagen gel contraction assay. The in vivo elbow rat (n = 3-10/group) injury model evaluated the effects of orally administered SV and LS at two dosing strategies [i.e., low dose/high frequency/short duration (D1) vs. high dose/low frequency/long duration (D2)] on post-mortem elbow range of motion (via biomechanical testing) as well as capsule fibrosis and cartilage damage (via histopathology). The in vitro gel contraction assay coupled with live/dead staining (n = 3-19/group) evaluated the effects of SV and LS at various concentrations (i.e., 1, 10, 100 µM) and durations (i.e., continuous, short, or delayed) on the contractibility and viability of fibroblasts/myofibroblasts [i.e., NIH3T3 fibroblasts with endogenous transforming growth factor-beta 1 (TGFβ1)]. In vivo, no drug strategy prevented elbow contracture biomechanically. Histologically, only SV-D2 modestly reduced capsule fibrosis but maintained elevated cellularity and tissue hypertrophy, and both SV strategies lessened cartilage damage. SV modest benefits were localized to the anterior region, not the posterior, of the joint. Neither LS strategy had meaningful benefits in capsule nor cartilage. In vitro, irrespective of the presence of TGFβ1, SV (≥10 μM) prevented gel contraction partly by decreasing cell viability (100 μM). In contrast, LS did not prevent gel contraction or affect cell viability. This study demonstrates that SV, but not LS, might be suitable prophylactic drug therapy in two preclinical models of elbow PTJC. Results provide initial insight to guide future preclinical studies aimed at preventing or mitigating elbow PTJC.

COVID-19 in Joint Ageing and Osteoarthritis: Current Status and Perspectives

COVID-19 is a trending topic worldwide due to its immense impact on society. Recent trends have shifted from acute effects towards the long-term morbidity of COVID-19. In this review, we hypothesize that SARS-CoV-2 contributes to age-related perturbations in endothelial and adipose tissue, which are known to characterize the early aging process. This would explain the long-lasting symptoms of SARS-CoV-2 as the result of an accelerated aging process. Connective tissues such as adipose tissue and musculoskeletal tissue are the primary sites of aging. Therefore, current literature was analyzed focusing on the musculoskeletal symptoms in COVID-19 patients. Hypovitaminosis D, increased fragility, and calcium deficiency point towards bone aging, while joint and muscle pain are typical for joint and muscle aging, respectively. These characteristics could be classified as early osteoarthritis-like phenotype. Exploration of the impact of SARS-CoV-2 and osteoarthritis on endothelial and adipose tissue, as well as neuronal function, showed similar perturbations. At a molecular level, this could be attributed to the angiotensin-converting enzyme 2 expression, renin-angiotensin system dysfunction, and inflammation. Finally, the influence of the nicotinic cholinergic system is being evaluated as a new treatment strategy. This is combined with the current knowledge of musculoskeletal aging to pave the road towards the treatment of long-term COVID-19.

Recent Advances in Pharmacological Intervention of Osteoarthritis: A Biological Aspect

Osteoarthritis (OA) is a degenerative joint disease in the musculoskeletal system with a relatively high incidence and disability rate in the elderly. It is characterized by the degradation of articular cartilage, inflammation of the synovial membrane, and abnormal structure in the periarticular and subchondral bones. Although progress has been made in uncovering the molecular mechanism, the etiology of OA is still complicated and unclear. Nevertheless, there is no treatment method that can effectively prevent or reverse the deterioration of cartilage and bone structure. In recent years, in the field of pharmacology, research focus has shifted to disease prevention and early treatment rather than disease modification in OA. Biologic agents become more and more attractive as their direct or indirect intervention effects on the initiation or development of OA. In this review, we will discuss a wide spectrum of biologic agents ranging from DNA, noncoding RNA, exosome, platelet-rich plasma (PRP), to protein. We searched for key words such as OA, DNA, gene, RNA, exosome, PRP, protein, and so on. From the pharmacological aspect, stem cell therapy is a very special technique, which is not included in this review. The literatures ranging from January 2016 to August 2021 were included and summarized. In this review, we aim to help readers have a complete and precise understanding of the current pharmacological research progress in the intervention of OA from the biological aspect and provide an indication for the future translational studies.

The effects of different antihypertensive drugs on pain and joint space width of knee osteoarthritis - A comparative study with data from Osteoarthritis Initiative

Hypertension was one common comorbidity of knee osteoarthritis (KOA), but the effect of different types of antihypertensive drugs on pain and joint space width (JSW) was unclear and not compared. Four hundred ninety KOA patients using one of the beta-blockers, ACE inhibitors, angiotensin receptor blockers, Calcium channel blockers (CCBs), or thiazide diuretics were followed for four years. The blood pressure, cumulative knee replacement rate, Womac pain, and JSW were compared among groups. All data were from the Osteoarthritis Initiative project. The CCBs group has the highest systolic blood pressure, replacement rate, and pain score at most visit timepoints. At baseline, the CCBs group was with significantly higher pain score than the beta-blockers group (3.3 vs 1.3, p < .05), the angiotensin receptor blockers group (3.3 vs 1.4, p < .05), and the thiazide diuretics group (3.3 vs 1.6, p < .05) in male; the CCBs group was with significantly higher pain score than the beta-blockers group (3.8 vs 2.0, p < .01), and the angiotensin receptor blockers group (3.8 vs 2.2, p < .05) in female. The results of females at 36 months were similar to the baseline. Among the common antihypertensive drugs, CCBs were associated with high replacement rates, high pain scores, and less JSW in KOA patients.

Prediction of the Molecular Mechanism of Eucommiae Cortex - Achyranthis Bidentatae Radix in the treatment of Osteoarthritis: Network Pharmacology and Molecular Docking

OBJECTIVE

To retrieve the core drug of osteoarthritis in clinic using Data Mining, predict the drug molecular action target through the Network Pharmacology, identify the key nodes of the interaction by combining with the related targtes of osteoarthritis, explore the pharmacological mechanism of Traditional Chinese Medicine against osteoarthritis and other possible mechanisms of actions.

METHODS

to retrieve the commonly used therapeutic formulations for osteoarthritis patients in clinical with PubMed, CNKI, VIP, CBM, WanFang Database and other databases, and screen out the core drugs through the Ancient and Modern Medical Case Cloud Platform and software Gephi, filter out the core drug molecules and targets combined with TCMSP database and the targets of osteoarthritis in Genecard and OMIM database, plunge those data into R project and Cytoscape to construct the intersection model of Drug molecule-osteoarthritis, establish PPI network and GO and conduct KEGG enrichment analysis with String database. Vina molecular docking was finally implemented to draw molecular docking diagram, and the results were analyzed after comprehensive analysis.

RESULTS

The core drug pairs were identified as "Eucommiae Cortex - Achyranthis Bidentatae Radix" through correlation analysis, complex network analysis based on the coefficient. "Eucommiae Cortex - Achyranthis Bidentatae Radix" can intervene cell behavior through multiple pathways and regulate cell metabolism, cytokine synthesis, oxidative and cellular immunity with the help of topology analysis in String Database.

CONCLUSIONS

The core molecules of Quercetin and Kaempferol derived from "Eucommia bark - achyranthes" can change the spatial conformation of PTGSs by hydrogen bonding with PTGSs, the hydrophobic bonds and van der Waals forces generated by Baicalein, Wogonin and β-carotene, thereby changing the activity of PTGSs and affecting bone properties the process of osteoarthritis.

Tissue Renin-Angiotensin System (tRAS) Induce Intervertebral Disc Degeneration by Activating Oxidative Stress and Inflammatory Reaction

Lumbar intervertebral disc degeneration (IDD) has been the major contributor to low back pain (LBP). IDD is an chronic inflammation process, with the activation of plentiful inflammation-related cytokines and ECM degradation-related enzymes. In the past few years, hypertension has been reported to correlate with LBP. In addition, the local tissue renin-angiotensin system (tRAS) has been identified in multiple tissues, including the spinal cord, skin, kidney, heart, and bone. Recently, tRAS has also been established in both bovine and human intervertebral disc tissues, especially in the degenerated disc tissue. However, the exact of tRAS and IDD remains unknown. In this present study, proteomic analysis, molecular biology analysis, and animal model were all used. Firstly, we revealed that tRAS was excessively activated in the human degenerated intervertebral disc tissue via proteomic analysis and molecular biology analysis. Then, in vitro experiment suggested that Ang II could decrease the cell viability of human NP cells and promote NP cell apoptosis, senescence, oxidative stress, and NLRP3 activation in human NP cells. In addition, Ang II could also trigger degeneration and fibrosis phenotype in human NP cells. Finally, the animal model demonstrated that the local activated ACE/Ang II axis in the NP tissue could accelerate IDD in aging spontaneously hypertensive rats (SHR). Collectively, the degenerated intervertebral disc tissue showed excessively activated tRAS, and local activated tRAS could induce NP cell senescence, apoptosis, oxidative stress, and inflammatory reaction to promote IDD. These biological effects of Ang II on human NP cells may provide novel insight into further treatment of IDD.

The Beneficial Effect of an Intra-articular Injection of Losartan on Microfracture-Mediated Cartilage Repair Is Dose Dependent

BACKGROUND

A previous publication demonstrated that the oral intake of losartan promoted microfracture-mediated hyaline-like cartilage repair in osteochondral defects of a rabbit knee model. However, an intra-articular (IA) injection of losartan may have direct beneficial effects on cartilage repair and has not been studied.

PURPOSE

To determine the dosage and beneficial effects of an IA injection of losartan on microfracture-mediated cartilage repair and normal cartilage homeostasis.

STUDY DESIGN

Controlled laboratory study.

METHODS

Rabbits were divided into 5 groups (n = 6 each): a microfracture group (MFX group) and 4 different losartan treatment groups that received varying doses of IA losartan (0.1, 1, 10, and 100 mg per knee). An osteochondral defect (5 mm) was created in the trochlear groove cartilage of 1 limb in each rabbit, and 5 microfracture perforations were made in the osteochondral defect. Both the injured and the contralateral knee joints were injected with IA losartan immediately after microfracture and at 2 and 4 weeks after surgery. Rabbits were sacrificed at 6 weeks after surgery for analysis including gross observation, micro-computed tomography, histology, and reverse transcription quantitative polymerase chain reaction.

RESULTS

Micro-computed tomography and gross observation demonstrated comparable subchondral bone healing and hyaline-like cartilage morphology in the 0.1-, 1-, and 10-mg losartan groups relative to the MFX group. Conversely, the 100-mg losartan group showed neither bony defect healing nor cartilage repair. Histology revealed higher O'Driscoll scores and hyaline-like cartilage regeneration in the 1-mg losartan group compared with the MFX group. In contrast, the 100-mg losartan group showed the lowest histology score and no cartilage repair. An IA injection of losartan at the doses of 0.1, 1, and 10 mg did not cause adverse effects on uninjured cartilage, while the 100-mg dose induced cartilage damage. Quantitative polymerase chain reaction results showed downregulation of the transforming growth factor β (TGF-β) signaling pathway after IA losartan injection.

CONCLUSION

An IA injection of losartan at the dose of 1 mg was most effective for the enhancement of microfracture-mediated cartilage repair without adversely affecting uninjured cartilage. Conversely, a high dose (100 mg) IA injection of losartan inhibited cartilage repair in the osteochondral defect and was chondrotoxic to normal articular cartilage.

CLINICAL RELEVANCE

An IA injection of losartan at an optimal dosage represents a novel microfracture enhancement therapy and warrants a clinical trial for future clinical applications.

Azilsartan prevented AGE-induced inflammatory response and degradation of aggrecan in human chondrocytes through inhibition of Sox4

Advanced glycation end products (AGEs)-induced inflammation and degradation of aggrecan in human chondrocytes play an important role in the progression and development of osteoarthritis (OA). Azilsartan, an angiotensin II receptor antagonist, has been licensed for the treatment of high blood pressure. However, the effects of Azilsartan in OA and AGEs-induced damages in chondrocytes have not been previously reported. The injured chondrocytes model was established by incubating with 5 μmol/L AGEs. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide was used to evaluate the cell viability of treated SW1353 cells. The gene expression levels of interleukin-1α (IL-1α), tumor necrosis factor-β (TNF-β), IL-6, a disintegrin-like and metallopeptidase with thrombospondin type motif-4 (ADAMTS-4), ADAMTS-5, Aggrecan, and Sox-4 were evaluated using quantitative real-time polymerase chain reaction and their protein levels were determined using enzyme-linked immunosorbent assay or Western blot analysis. Mitogen-activated protein kinase p38 pathway was surveyed using phosp-p38 level and its specific inhibitor SB203580 was employed to block the p38 pathway. The overexpression of Sox4 plasmid was transfected into SW1353 cells to assess its regulation on ADAMTS-4 and ADAMTS-5. Azilsartan reduced AGEs-induced production of proinflammatory cytokines, such as IL-1α, TNF-β, and IL-6. Azilsartan prevented AGEs-induced expressions of ADAMTS-4 and ADAMTS-5 as well as the reduction of aggrecan. Mechanistically, AGEs treatment increased the expression of Sox4 in a dose-dependent manner. AGE treatment increased the level of phosphorylated p38. However, treatment with the p38 inhibitor SB203580 inhibited AGEs-induced expression of Sox4, suggesting that AGEs-induced expression of Sox4 is mediated by p38. Furthermore, Azilsartan suppressed AGEs-induced phosphorylation of p38 and expression of Sox4. Finally, the overexpression of Sox4 abolished the inhibitory effects of Azilsartan against the expressions of ADAMTS-4 and ADAMTS-5. Azilsartan treatment prevented AGEs-induced inflammatory response and degradation of aggrecan through inhibition of Sox4.

Targeting the Protective Arm of the Renin-Angiotensin System: Focused on Angiotensin-(1-7)

The in vivo application and efficacy of many therapeutic peptides is limited because of their instability and proteolytic degradation. Novel strategies for developing therapeutic peptides with higher stability toward proteolytic degradation would be extremely valuable. Such approaches could improve systemic bioavailability and enhance therapeutic effects. The renin-angiotensin system (RAS) is a hormonal system within the body essential for the regulation of blood pressure and fluid balance. The RAS is composed of two opposing classic and protective arms. The balance between these two arms is critical for the homeostasis of the body's physiologic function. Activation of the RAS results in the suppression of its protective arm, which has been reported in inflammatory and pathologic conditions such as arthritis, cardiovascular diseases, diabetes, and cancer. Clinical application of angiotensin-(1-7) [Ang-(1-7)], a RAS critical regulatory peptide, augments the protective arm and restores balance hampered by its enzymatic and chemical instability. Several attempts to increase the half-life and efficacy of this heptapeptide using more stable analogs and different drug delivery approaches have been made. This review article provides an overview of efforts targeting the RAS protective arm. It provides a critical analysis of Ang-(1-7) or its homologs' novel drug delivery systems using different administration routes, their pharmacological characterization, and therapeutic potential in various clinical settings. SIGNIFICANCE STATEMENT: Ang-(1-7) is a unique peptide component of the renin-angiotensin system with vast potential for clinical applications that modulate various inflammatory diseases. Novel Ang-(1-7) peptide drug delivery could compensate its lack of stability for effective clinical application.

Angiotensin-(1-7) attenuates collagen-induced arthritis via inhibiting oxidative stress in rats

The present study was designed to investigate the anti-rheumatic effects and the mechanism of angiotensin (Ang)-(1-7) in rat models with collagen-induced arthritis (CIA). The CIA model was established using male Wistar rats by intradermal injection of bovine collagen-II in complete Freund's adjuvant at the base of the tail. The levels of angiotensin converting enzyme 2 (ACE2)/Ang-(1-7)/Mas receptor (MasR) were reduced in CIA rats. The attenuation of paw swelling and arthritis scores and improvement of indexes of spleen and thymus were done by Ang-(1-7) injection in CIA rats. The increased levels of inflammatory cytokines, such as interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α, and interferon (IFN)-γ in the serum and hind paw were blocked by Ang-(1-7) administration. In addition, enhanced NADPH oxidase (Nox) activity, increased levels of superoxide anions and malondialdehyde (MDA), and weakened superoxide dismutase (SOD) activity, were all reversed by treatment with Ang-(1-7). Nox1 overexpression reversed the suppressing effects of Ang-(1-7) on paw swelling and arthritis scores in CIA rats. The Ang-(1-7)-induced improvement in spleen and thymus indexes in CIA rats was abolished by Nox1 overexpression. Nox1 overexpression reversed the inhibitory effects of Ang-(1-7) by increasing IL-1β, IL-6, TNF-α, and IFN-γ levels in the serum and hind paw of CIA rats. These results demonstrated that Nox1 increased the oxidative stress in arthritis, and Ang-(1-7) improved rheumatism in arthritis via inhibiting oxidative stress.

[Expressions of Renin, angiotensin converting enzyme, angiotensin receptor 1, and angiotensin receptor 2 in synovial tissue of osteoarthritis at different stages]

OBJECTIVE

To study the expressions of Renin, angiotensin converting enzyme (ACE), angiotensin receptor 1 (AT1R), and AT2R in synovial tissue of osteoarthritis (OA) at different stages.

METHODS

The patients who were treated with upper knee amputation because of trauma or total knee arthroplasty for OA between January 2018 and December 2018 were enrolled. Among them, 32 patients who met the selection criteria were included in the study. According to the Kellgren-Lawrence (K-L) X-ray classification, they were allocated to normal synovial group (group A, n=9), moderate OA synovial group (group B, n=11, K-L level 3), and advanced OA synovial group (group C, n=12, K-L level 4). The relative expressions of Renin, ACE, AT1R, and AT2R mRNAs and proteins were detected by real-time fluorescence quantitative PCR (qRT-PCR) and Western blot.

RESULTS

The relative expressions of Renin, ACE, and AT1R mRNAs and proteins were significantly higher in group B and group C than in group A ( P<0.05). The relative expressions of ACE and AT1R mRNAs and proteins and Renin protein were significantly higher in group C than in group B ( P<0.05). However, the relative expressions of AT2R mRNA and protein were lower in group B and group C than in group A ( P<0.05), and in group C than in group B ( P<0.05).

CONCLUSION

The expressions of Renin, ACE, and AT1R in synovial tissue of osteoarthritis significantly increase as the K-L level increased, and the expression of AT2R decreases. Renin, ACE, AT1R, and AT2R have a certain degree of correlation with the development of OA.

Differential Expression of Renin-Angiotensin System-related Components in Patients with Rheumatoid Arthritis and Osteoarthritis

BACKGROUND

The purpose of this study was to demonstrate the role of renin-angiotensin system (RAS)-related components, vascular endothelial growth factor (VEGF) and atrial metalloproteinase-13 (MMP-13) in synovial tissue and synovial fluid from patients with rheumatoid arthritis (RA) and osteoarthritis (OA).

MATERIALS AND METHODS

Thirty-four patients with RA and 41 patients with OA were included in the study. Renin, angiotensin-converting enzyme (ACE), VEGF and MMP-13 protein levels in the synovial fluid were measured by enzyme-linked immunosorbent assay. Quantitative real-time polymerase chain reaction analysis, western blot analysis and immunohistochemistry were used to quantify renin, ACE, angiotensin type 1 and type 2 receptors, VEGF and MMP-13 in OA and RA. Additionally, the correlation was determined by Pearson's coefficient.

RESULTS

In synovial fluid, expression levels of renin, ACE, VEGF and MMP-13 in patients with RA were significantly higher than those in patients with OA. In synovial tissue, the RAS components VEGF and MMP-13 were also elevated in patients with RA. The results of immunohistochemistry in synovial tissue also showed that the RAS components VEGF and MMP-13 were significantly increased in patients with RA. Notably, the Pearson coefficient demonstrated that the levels of the RAS components were positively correlated with the expression of VEGF and MMP-13 in OA and RA.

CONCLUSIONS

The present results suggest that RAS-related components in RA and OA, including renin, ACE, angiotensin type 1 and type 2 receptors, are associated with increased expression of VEGF and play an important role in angiogenesis. Furthermore, there was a significant positive correlation between the expression of VEGF and MMP-13.