Collagen-induced arthritis increases inducible nitric oxide synthase not only in aorta but also in the cardiac and renal microcirculation of mice

Targeting the serum marker interleukin 9 improves the underlying characterization and immune homeostasis in rheumatoid arthritis

Introduction

Rheumatoid factor (RF) and anti-citrullinated peptide antibodies (ACPA) are serological markers used for diagnosing rheumatoid arthritis (RA), an autoimmune disease characterized by inflammatory joint damage. However, there is a subset of RA patients who test negative for both RF and ACPA, known as seronegative rheumatoid arthritis (SNRA).

Material and methods

The levels of serum markers were examined in both clinical samples and a rat model of type II collagen-induced RA (CIA). The effect of interleukin 9 (IL-9) on RA was investigated using recombinant rat IL-9 (rrIL-9), anti-rat IL-9 neutralizing monoclonal antibody (mAb), and control IgG antibody in the CIA rat. The severity of arthritis was assessed. Treg and Th17 cells, M1 and M2 macrophages, and inflammatory cytokine levels were analyzed.

Results

We observed higher levels of IL-9 in clinical samples from SNRA patients compared to the normal group. Rat models of CIA exhibit increased arthritis scores, weight loss, paw swelling, and severe joint damage. IL-9 was the most sensitive serum marker for the diagnosis of RA in serum assays of CIA rats. IL-9 increased arthritis scores and cartilage damage, whereas treatment with IL-9 inhibitors produced the opposite effect. IL-9 inhibitors promoted Treg/Th17 homeostasis, decreased M1 macrophages, increased M2 macrophages, and decreased levels of inflammatory cytokines in joint tissues.

Conclusions

These results suggest that IL-9 has potential as a diagnostic marker for SNRA. Inhibition of IL-9 could reduce the severity of arthritis in CIA rats by ameliorating inflammation and modulating the Treg/Th17 immune balance, M2 and M1 macrophage activation.

Adjuvant-induced arthritis promotes vascular hyporesponsiveness to phenylephrine through a nitric oxide-related mechanism

Arthritis has important cardiovascular repercussions. Phenylephrine-induced vasoconstriction is impaired in rat aortas in the early phase of the adjuvant-induced arthritis (AIA), around the 15th day post-induction. Therefore, the present study aimed to verify the effects of AIA on hyporesponsiveness to phenylephrine in rat aortas. AIA was induced by intradermal injection of Mycobacterium tuberculosis (3.8 mg/dL) in the right hind paw of male Wistar rats (n=27). Functional experiments in isolated aortas were carried out 15 days after AIA induction. Morphometric and stereological analyses of the aortas were also performed 36 days after the induction of AIA. AIA did not promote structural modifications in the aortas at any of the time points studied. AIA reduced phenylephrine-induced contraction in endothelium-intact aortas, but not in endothelium-denuded aortas. However, AIA did not change KCl-induced contraction in either endothelium-intact or denuded aortas. L-NAME (non-selective NOS inhibitor), 1400W (selective iNOS inhibitor), and ODQ (guanylyl cyclase inhibitor) reversed AIA-induced hyporesponsiveness to phenylephrine in intact aortas. 7-NI (selective nNOS inhibitor) increased the contraction induced by phenylephrine in aortas from AIA rats. In summary, the hyporesponsiveness to phenylephrine induced by AIA was endothelium-dependent and mediated by iNOS-derived NO through activation of the NO-guanylyl cyclase pathway.

Orchiectomy but not adjuvant-induced arthritis induces structural modifications in rat aortas

Purpose: This study aimed to verify whether Adjuvant-Induced Arthritis (AIA) and/or Orchiectomy (ORX) modify the expression of the Nox1, Nox2 and Nox4 isoforms, the endothelial function or the structure of rat aortas. Methods: Sixty-three Wistar rats were distributed into four groups: 1) Control; 2) ORX; 3) AIA; 4) Orchiectomy plus to Arthritis-induction (ORX/AIA). Thus, 21 days after the onset of AIA (by intradermal injection of Mycobacterium tuberculosis), the presence of Nox1, Nox2 and Nox4, the acetylcholine (ACh)-induced relaxation and the media layer thickness were assessed in the aorta taken from these animals. Results: The Nox1, Nox2 and Nox4 were immunostained in intima, media and adventitia layers of aortas taken from all studied groups and AIA apparently increased this immunostaining. These modifications of Nox1, Nox2 or Nox4 expression, however, were not confirmed by Western blotting. In addition, neither AIA nor ORX changed the endothelial function, but ORX increased the media layer thickness in the studied aortas. Conclusion: The present study showed weak clues of increased expression of Nox1, Nox2 and Nox4 as a result of AIA, as well as of Nox1 reduction caused by ORX. In addition, the endothelial function was not modified in the aortas of these animals by both AIA and/or ORX. On the other hand, ORX increased significantly the aorta media layer thickness in the studied animals, which was apparently mitigated by AIA.

Perivascular brown adipocytes-derived kynurenic acid relaxes blood vessel via endothelium PI3K-Akt-eNOS pathway

OBJECTIVE

Several metabolites from the kynurenine pathway of tryptophan metabolism play a critical role in vascular function and vascular wall remodeling. This study aimed to test whether metabolite kynurenic acid (KYNA) from the kynurenine pathway relaxes blood vessels.

APPROACH AND RESULTS

We employed histological staining, in vitro cell culture, Western blotting, real-time PCR, and nitric oxide detection to validate kynurenine aminotransferase (KAT) localization in the vasculature as well as KYNA action on endothelial cells. We also detected vascular reactivity by organ chamber and monitored blood pressure by telemetry to investigate the regulation effect of KYNA on vascular tone. The results presented that perivascular adipose tissue (PVAT) from mice thoracic aorta had robust staining of anti-KAT1 and KYNA than PVAT from the abdominal aorta and mesenteric artery, which is consistent with the expression profile of brown adipocyte marker uncoupling protein 1. KYNA, metabolized from kynurenine by KAT, relaxed pre-contracted both aortic ring and mesenteric artery. In addition, KYNA derived from KAT in PVAT participates in the cross-talk between PVAT and vessel by mediating PVAT inhibition on agonist-induced thoracic aorta contraction. Furthermore, intraperitoneal injection of KYNA in mice reduced blood pressure. The vessel relaxation effect of KYNA was through the endothelium-dependent PI3K-Akt-eNOS pathway. Finally, the high-fat diet decreased KAT1 expression in perithoracic aortic fat and led to KYNA reduction in blood.

CONCLUSIONS

Our research identified KYNA generated by KAT as a novel perivascular brown adipocyte-derived vascular relaxation factor and suggests that KYNA reduction is a critical event in vascular dysfunction under obese condition.

Angiotensin involvement in kidney injury induced by rheumatoid arthritis in rat

Renal injury induced by rheumatoid arthritis is not clear and may be related to the angiotensin II. We aim to investigate the adjuvant-induced arthritis (AIA) injury in rat kidney, focusing the angiotensin II/AT1 pathway. Male Wistar rats were allocated in to three groups: Control, AIA and AIA plus losartan. The AIA was induced by injection of 100 µL of an emulsion of dissected Mycobacterium tuberculosis (50 mg/mL) on the paw. Treatment with losartan was initiated on the first day of immunization (daily subcutaneous injection, 1 mg/kg). After 60 days post immunization, we evaluated kidney function by plasma creatinine, urea and uric acid levels and creatinine depuration; kidney injury by apoptosis analysis and inflammation markers such as macrophages, transforming growth factor beta (TGF-β) and inducible nitric oxide synthase (iNOS) expression; oxidative stress by plasma thiobarbituric acid reactive substances (TBARS); renal expression of angiotensin receptors subtype 1 (AT1 ) and 2 (AT2 ) and plasma concentration of angiotensin II. AIA rats showed elevated plasma levels of creatinine, urea, uric acid, TBARS and Ang II and reduced creatinine depuration, and enhanced kidney macrophage number, TGF-β, caspase-3, iNOS and AT1 /AT2 receptors expression. The losartan reduced plasma creatinine and its clearance, reduced macrophages and the expression of TGF-β and iNOS in renal tissues, and reduced plasma TBARS. We conclude that AIA causes kidney injury by a physiopathological mechanism that involves AT1  stimulation in renal tissue, elevating the presence of macrophages, the expression of TGF-β and iNOS, as well the local oxidative stress, which contribute to renal function deterioration.

Animal models to study pathogenesis and treatments of cardiac disorders in rheumatoid arthritis: Advances and challenges for clinical translation

Although cardiac diseases such as acute myocardial infarction, heart failure and arrhythmias are the leading cause of cardiovascular complications in rheumatoid arthritis (RA), their pathogenesis is far from being understood and optimal therapeutic options to treat specifically these disorders in RA are lacking. Preclinical studies on animal models of arthritis can help to decipher the complex link between arthritis and the heart, and to identify critical pathways and novel therapeutic targets. This review presented the available data on cardiac disorders in animal models of RA, as well as the current knowledge on pathophysiology and pharmacology of these disorders. Future directions for translational studies in a cardiorheumatic perspective are proposed.

Cardiac Dysfunction in Rheumatoid Arthritis: The Role of Inflammation

Rheumatoid arthritis is a chronic, systemic inflammatory disease that carries an increased risk of mortality due to cardiovascular disease. The link between inflammation and atherosclerotic disease is clear; however, recent evidence suggests that inflammation may also play a role in the development of nonischemic heart disease in rheumatoid arthritis (RA) patients. We consider here the link between inflammation and cardiovascular disease in the RA community with a focus on heart failure with preserved ejection fraction. The effect of current anti-inflammatory therapeutics, used to treat RA patients, on cardiovascular disease are discussed as well as whether targeting resolution of inflammation might offer an alternative strategy for tempering inflammation and subsequent inflammation-driven comorbidities in RA.

Exercise protects against cardiac and skeletal muscle dysfunction in a mouse model of inflammatory arthritis

Rheumatoid arthritis (RA) is a systemic inflammatory arthritis impacting primarily joints and cardiac and skeletal muscle. RA's distinct impact on cardiac and skeletal muscle tissue is suggested by studies showing that new RA pharmacologic agents strongly improve joint inflammation, but have little impact on RA-associated mortality, cardiovascular disease, and sarcopenia. Thus, the objective is to understand the distinct effects of RA on cardiac and skeletal muscle, and to therapeutically target these tissues through endurance-based exercise as a way to improve RA mortality and morbidity. We utilize the well-characterized RA mouse model, the K/BxN mouse, to investigate cardiac and skeletal muscle pathologies, including the use of wheel-running exercise to mitigate these pathologies. Strikingly, we found that K/BxN mice, like patients with RA, also exhibit both cardiac and skeletal muscle myopathies that were correlated with circulating IL-6 levels. Three months of wheel-running exercise significantly improved K/BxN joint swelling and reduced systemic IL-6 concentrations. Importantly, there were morphological, gene expression, and functional improvements in both the skeletal muscle and cardiac myopathies with exercise. The K/BxN mouse model of RA recapitulated important RA clinical comorbidities, including altered joint, cardiac and skeletal muscle function. These morphological, molecular, and functional alterations were mitigated with regular exercise, thus suggesting exercise as a potential therapeutic intervention to lessen disease activity in the joint and the peripheral tissues, including the heart and skeletal muscle.NEW & NOTEWORTHY RA, even when controlled, is associated with skeletal muscle weakness and greater risk of cardiovascular disease (CVD). Using exercise as a therapeutic against, the progression of RA is often avoided due to fear of worsening RA pathology. We introduce the K/BxN mouse as an RA model to study both myocardial and skeletal muscle dysfunction. We show that endurance exercise can improve joint, cardiac, and skeletal muscle function in K/BxN mice, suggesting exercise may be beneficial for patients with RA.

CXC chemokine receptor 3 antagonist AMG487 shows potent anti-arthritic effects on collagen-induced arthritis by modifying B cell inflammatory profile

Several studies have suggested that chemokine receptors are important mediators of inflammatory response in rheumatoid arthritis (RA). B cells are also known to play an important role in RA pathology. C-X-C chemokine receptor type 3 (CXCR3) is considered a potential therapeutic target in different inflammatory diseases; however, the mechanism remains unclear. Here, we evaluated the potentially protective effect of AMG487, a selective CXCR3 antagonist, in collagen-induced arthritis (CIA) mouse model. CIA mice were treated with AMG487 (5 mg/kg) every 48 h, from day 21 until day 41. We then investigated the effect of AMG487 on NF-κB p65-, NOS2-, MCP-1-, TNF-α-, IFN-γ, IL-4-, and IL-27-producing CD19⁺ B cells in the spleen through flow cytometry. We also evaluated the mRNA and protein expression levels of these molecules using RT-PCR and western blotting in the knee tissues. Our results revealed that AMG487-treated mice showed decreased NF-κB p65-, NOS2-, MCP-1-, and TNF-α-, and increased IL-4-, and IL-27-producing CD19⁺ B cells compared with the control mice. Additionally, AMG487 treatment significantly down regulated NF-κB p65, NOS2, TNF-α, and IFN-γ, and upregulated IL-4 and IL-27 mRNA and protein expression levels compared with the control. Thus, our study shows that AMG487 exerts its anti-arthritic effect by potently downregulating inflammatory B cell signaling. Based on our observations, we propose that AMG487 could serve as a potential novel therapeutic agent for inflammatory and autoimmune diseases, including RA.

Gold-Coated Superparamagnetic Iron Oxide Nanoparticles Attenuate Collagen-Induced Arthritis after Magnetic Targeting

The aim of the study was to evaluate if gold-coated superparamagnetic iron oxide nanoparticles (AuSPION) magnetic-targeted to the arthritic articulation of collagen induced arthritis (CIA) rats are able to ameliorate rheumatoid arthritis without producing significant biological adverse effects in comparison to colloidal Au nanoparticles (AuC) and metotrexate (MTX). Male Wistar rats were divided into control; arthritic; AuSPION (150 μg kg^-1); AuC (150 μg kg^-1) and MTX (2.5 μg kg^-1). Treatments were administered thrice every other day by the intraperitoneal route 15 min after all groups had a neodymium magnet coupled to the right ankle joint (kept for 1 h). Paw edema and body weight were measured weekly. Joint sections were evaluated by Haematoxylin & Eosin and immunohistochemistry (TNF-α, IL-1β). Biomarkers of oxidative stress were used to evaluate toxicity. Among the evaluated treatments, AuSPION led to significant clinical improvements (decreased edema and infiltration by leukocytes as well as less positively immunostained cells for both TNF-α and IL-1β in synovium) accompanied by a lack of toxicity as indicated by redox state and genotoxicity assays. Our results clearly indicate that the magnetic targeting of AuSPION suppresses joint edema and inflammation, cytokine expression as well as the redox imbalance, thereby contributing to an amelioration of arthritis severity in CIA rats. The results demonstrate for the first time the potentiality of AuSPION administration under a magnetic field as an attractive alternative for future treatments of rheumatic diseases.

Repercussions of adjuvant-induced arthritis on body composition, soleus muscle, and heart muscle of rats

This study investigated the repercussions of adjuvant-induced arthritis (AIA) on body composition and the structural organization of the soleus and cardiac muscles, including their vascularization, at different times of disease manifestation. Male rats were submitted to AIA induction by intradermal administration of 100 μL of Mycobacterium tuberculosis (50 mg/mL), in the right hind paw. Animals submitted to AIA were studied 4 (AIA4), 15 (AIA15), and 40 (AIA40) days after AIA induction as well as a control group of animals not submitted to AIA. Unlike the control animals, AIA animals did not gain body mass throughout the evolution of the disease. AIA reduced food consumption, but only on the 40th day after induction. In the soleus muscle, AIA reduced the wet mass in a time-dependent manner but increased the capillary density by the 15th day and the fiber density by both 15 and 40 days after induction. The diameter of the soleus fiber decreased from the 4th day after AIA induction as well as the capillary/fiber ratio, which was most evident on the 40th day. Moreover, AIA induced slight histopathological changes in the cardiac muscle that were more evident on the 15th day after induction. In conclusion, AIA-induced changes in body composition as well as in the soleus muscle fibers and vasculature have early onset but are more evident by the 15th day after induction. Moreover, the heart may be a target organ of AIA, although less sensitive than skeletal muscles.

Circulating Insulin-like Growth Factor-1 Levels in Patients with Rheumatoid Arthritis: A Meta-analysis

BACKGROUND AND OBJECTIVES

Insulin-like growth factor-1 (IGF-1) levels have been investigated in rheumatoid arthritis (RA), however, produced inconsistent results. The purpose of this meta-analysis was to derive a more precise conclusion about serum/plasma IGF-1 levels in RA patients.

METHODS

PubMed, Embase and the Cochrane Library databases were searched up to December 2018 in English, and the studies comparing serum/plasma IGF-1 levels between RA group and healthy control group were what we are interested in. The Newcastle-Ottawa Scale (NOS) was used to assess the methodological quality of the included studies. The heterogeneity test was performed by the Cochrane Q statistic and I2 -statistic. The publication bias was evaluated by the funnel plot and Egger's test. The standard mean difference (SMD) with 95% confidence interval (CI) was calculated by the fixed-effects or random-effects model.

RESULTS

A total of eleven articles with 334 cases and 261 controls were finally included. Compared with the healthy group, the RA group had lower circulating IGF-1 levels (pooled SMD= -0.936, 95% CI= -1.382 to -0.489, p<0.001). The subgroup analysis showed that RA patients from Asia (SMD= -0.645, 95% CI= -1.063 to -0.228, p= 0.002) and Europe (SMD= -1.131, 95% CI= -1.767 to -0.495, p<0.001) had lower circulating IGF-1 levels, no significant difference in plasma/serum IGF-1 levels was observed in RA patients from America. Sensitivity analysis indicated the stability and credibility of the overall effect sizes.

CONCLUSION

Patients with RA have lower circulating IGF-1 level than healthy controls, particularly for patients from Asia and Europe. Further studies are necessary to elucidate the role of IGF-1 in the pathological process of RA.

iNOS dependent and independent phases of lymph node expansion in mice with TNF-induced inflammatory-erosive arthritis

Introduction

A pivotal effect of lymphatic vessel (LV) function in joint homeostasis was identified in the tumor necrosis factor-transgenic (TNF-Tg) mouse model of rheumatoid arthritis (RA). Specifically, loss of LV contractions is associated with progressive synovitis and erosions. Furthermore, draining lymph node expansion is a biomarker of arthritic progression, and both macrophages and lymphatic endothelial cells express inducible nitric oxide synthase (iNOS), which disrupts LV contraction and transport of immune cells to the draining lymph nodes. Therefore, to directly assess these relationships, we tested the hypothesis that TNF-Tg mice with global genetic ablation of iNOS (iNOS^−/−) will show delayed draining lymph node expansion, maintained LV contractions, and decreased synovitis and erosions.

Method

iNOS^−/−× TNF-Tg female and male mice, and control littermates (iNOS^−/−, TNF-Tg, and WT), were examined with (1) ultrasound to determine popliteal lymph node (PLN) volume and (2) near-infrared imaging (NIR) to assess popliteal LV contraction frequency, and differences between genotypes were assessed at 3, 4, 5, and 6 months of age. Knees and PLN were harvested at 4 months in females and 6 months in males, to assess synovitis, bone erosions, and cellular accumulation in PLN sinuses via histology.

Results

Initially, an increase in PLN volume was observed for both female and male iNOS^−/−× TNF-Tg and TNF-Tg compared to their WT and iNOS^−/− counterparts at 2 and 3 months, respectively. Subsequently, TNF-Tg PLNs continue to increase in volume, while iNOS^−/−× TNF-Tg did not increase in volume from the initial timepoints. WT and iNOS^−/− PLN volume was unchanged throughout the experiment. LV contraction frequency was increased at 4 months in females and 5 months in males, in the iNOS^−/−× TNF-Tg mice compared to the TNF-Tg. Synovitis and erosions were moderately reduced in iNOS^−/−× TNF-Tg versus TNF-Tg knees in females, while no differences in knee pathology were observed in males.

Conclusions

Genetic iNOS ablation maintains draining lymph node volume and LV function during TNF-induced inflammatory arthritis and is associated with moderately decreased joint inflammation and damage.

Cardiac phenotype in mouse models of systemic autoimmunity

Patients suffering from systemic autoimmune diseases are at significant risk of cardiovascular complications. This can be due to systemically increased levels of inflammation leading to accelerated atherosclerosis, or due to direct damage to the tissues and cells of the heart. Cardiac complications include an increased risk of myocardial infarction, myocarditis and dilated cardiomyopathy, valve disease, endothelial dysfunction, excessive fibrosis, and bona fide autoimmune-mediated tissue damage by autoantibodies or auto-reactive cells. There is, however, still a considerable need to better understand how to diagnose and treat cardiac complications in autoimmune patients. A range of inducible and spontaneous mouse models of systemic autoimmune diseases is available for mechanistic and therapeutic studies. For this Review, we systematically collated information on the cardiac phenotype in the most common inducible, spontaneous and engineered mouse models of systemic lupus erythematosus, rheumatoid arthritis and systemic sclerosis. We also highlight selected lesser-known models of interest to provide researchers with a decision framework to choose the most suitable model for their study of heart involvement in systemic autoimmunity.

Rutin and rutin-conjugated gold nanoparticles ameliorate collagen-induced arthritis in rats through inhibition of NF-κB and iNOS activation

Numerous studies have suggested that nuclear factor-κB (NF-κB) and inducible nitric oxide synthase (iNOS) are important mediators of inflammatory response in human and animal models of arthritis. Besides, oxidative stress markers, nitric oxide (NO) and peroxide (PO) are also major contributors in the pathogenesis of rheumatoid arthritis (RA). Over expression of these inflammatory mediators leads to the extracellular matrix degradation, and excessive cartilage and bone resorption, ultimately leading to the irreversible damage to joints. The aim of the present study was to investigate the anti-arthritic mechanism of bioflavonoids, rutin and rutin-conjugated gold nanoparticles (R-AuNPs) by determining their role in the modulation of NF-κB and iNOS expression in collagen-induced arthritis (CIA) model of rats. Arthritis was induced by the subcutaneous administration of bovine type II collagen. Treatment was started with rutin, indomethacin + rutin (I + R) and R-AuNPs on the day of CIA induction. The severity of arthritis was determined by measuring the arthritic score on alternate days until mean arthritic score of 4 was observed. The NO and PO levels were also analyzed in serum samples. NF-κB and iNOS expression levels were determined in spleen tissue samples by real time RT-PCR and immunohistochemistry. Marked reduction in the arthritic score as well as in the NO and PO levels was observed in the treated groups. A significant downregulation in the NF-κB and iNOS expression levels was also observed in the treatment groups compared to the arthritic control group. Collectively, the findings suggest potential clinical role of rutin and R-AuNPs in the treatment of rheumatoid arthritis.

Simvastatin ameliorates graft-vs-host disease by regulating angiopoietin-1 and angiopoietin-2 in a murine model

Angiopoietins play an important role in vascular endothelial function. Endothelial damage is an important pathogenesis relating with acute graft-versus-host disease (GVHD) after allogeneic hematopoietic stem cell transplantation (allo-HSCT), protecting endothelial cells (ECs) from damage may be a potent prophylaxis and therapeutic strategy of acute GVHD (aGVHD). In this study, we explored changes in Angiopoietin-1 (Ang-1) and Ang-2 expression in a aGVHD mouse model and determined whether simvastatin prevents GVHD through regulating Ang-1 and Ang-2 expression. In vitro simvastatin administration increased Ang-1 production and release but conversely inhibited Ang-2 release from EA.hy926 ECs. Simvastatin improved the survival of aGVHD mice, attenuated the histopathological GVHD grades and plasma levels of Ang-2, and elevated the plasma levels of Ang-1 as well as the aortic endothelial levels of Ang-1 and Ang-2. In summary, simvastatin represents a novel approach to combat GVHD by increasing Ang-1 production while suppressing Ang-2 release to stabilize endothelial cells.