Transcriptome sequencing reveals inflammation and macrophage heterogeneity in subacromial bursa from degenerative shoulder disorders.

PURPOSE: We aimed to investigate the transcriptomic alterations that occur in the subacromial bursa (SAB) following degenerative or traumatic shoulder diseases. MATERIALS AND METHODS: RNA sequencing was employed to evaluate the transcriptomic alterations of the SAB in individuals afflicted with degenerative rotator cuff tear (RCT), traumatic RCT and proximal humerus fracture (PHF). To gain insights into the biological significance of differentially expressed genes (DEGs), we conducted an enrichment analysis utilizing Gene Ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. We further utilized single-cell RNA sequencing datasets of SAB from a recently published study to explore the associated cellular dynamics and alterations. RESULTS: We detected 1,790 up-regulated and 1,964 down-regulated DEGs between degenerative RCT and PHF, 2,085 up-regulated and 1,919 down-regulated DEGs between degenerative RCT and traumatic RCT, and 20 up-regulated and 12 down-regulated DEGs between traumatic RCT and PHF. Given the similar expression pattern between traumatic RCT and PHF, they were integrated as the traumatic group. In comparison with the traumatic group, 1,983 up-regulated and 2,205 down-regulated DEGs were detected in degenerative SAB. Enrichment analysis of up-regulated DEGs uncovered an elevated inflammatory and immunologic responses in degenerative SAB. Single-cell transcriptomic analysis revealed macrophage represented the immune cell with the most DEGs between the degenerative and traumatic RCT. CONCLUSION: Our results revealed that the SAB in degenerative RCT exhibited a different transcriptional signature compared to that in traumatic RCT, and enrichment analysis showed immunologic and inflammatory activations. Macrophages may play a fundamental role in this process.

Histological and biochemical changes in a rat rotator cuff tear model with or without the subacromial bursa.

The subacromial bursa (SAB) plays an important role in the tendon healing process. Based on previous reports, co-culture of the rotator cuff (RC) and SAB have been shown to increase the tendon-related gene expressions, inflammatory cytokines, and tensile strength. However, the nature of the specific biochemical alterations during the inflammatory and repair phases of tendon healing with or without the SAB remain unknown. Using a full-thickness RC tear rat model, we determined how the presence or absence of the SAB alters the histological characteristics and gene expressions. After 3 and 6 weeks, tissues were collected for histological and real-time quantitative polymerase chain reaction (RT-qPCR) evaluations. Results showed greater cell density at 3 weeks, neovascularization and tendon thickening at 6 weeks with SAB preservation. Immunostaining revealed significant increases in type 3 collagen (COL3) expression at 6 weeks with SAB preservation. The RT-qPCR results showed that SAB preservation induced significant increases in the expression of scleraxis, matrix metalloproteinase-13 (MMP-13), interleukin-1ß (IL-1ß), and inducible nitric oxide synthase (iNOS) at 3 weeks and significant increases in COL3, IL-10, and arginase-1 (Arg-1) at 6 weeks. An RC tear undergoes more appropriate inflammatory and repair phases during the tendon healing process when the SAB is retained.

The subacromial bursa modulates tendon healing after rotator cuff injury in rats.

Rotator cuff injuries result in more than 500,000 surgeries annually in the United States, many of which fail. These surgeries typically involve repair of the injured tendon and removal of the subacromial bursa, a synovial-like tissue that sits between the rotator cuff and the acromion. The subacromial bursa has been implicated in rotator cuff pathogenesis and healing. Using proteomic profiling of bursa samples from nine patients with rotator cuff injury, we show that the bursa responds to injury in the underlying tendon. In a rat model of supraspinatus tenotomy, we evaluated the bursa's effect on the injured supraspinatus tendon, the uninjured infraspinatus tendon, and the underlying humeral head. The bursa protected the intact infraspinatus tendon adjacent to the injured supraspinatus tendon by maintaining its mechanical properties and protected the underlying humeral head by maintaining bone morphometry. The bursa promoted an inflammatory response in injured rat tendon, initiating expression of genes associated with wound healing, including Cox2 and Il6. These results were confirmed in rat bursa organ cultures. To evaluate the potential of the bursa as a therapeutic target, polymer microspheres loaded with dexamethasone were delivered to the intact bursae of rats after tenotomy. Dexamethasone released from the bursa reduced Il1b expression in injured rat supraspinatus tendon, suggesting that the bursa could be used for drug delivery to reduce inflammation in the healing tendon. Our findings indicate that the subacromial bursa contributes to healing in underlying tissues of the shoulder joint, suggesting that its removal during rotator cuff surgery should be reconsidered.

Biomolecules Related to Rotator Cuff Pain: A Scoping Review.

The pathophysiology of pain in patients suffering from rotator cuff (RC) tendinopathy or tears has been examined in various ways. Several molecules from tissue samples taken from the subacromial bursa, supraspinatus tendon, glenohumeral joint fluid, and synovium as well as from peripheral blood have been investigated. This article explores these studies, the assessed biomarkers, and groups their results according to the status of tendon integrity (tendinopathy or tear). Through a structured PubMed database search, 9 out of 658 articles were reviewed. Interleukins, mostly IL-1b and its antagonist, IL-1ra, matrix Metalloproteinases (MMPs), the vascular endothelial growth factor (VEGF) and TNF-a are biomarkers directly searched for correlation to pain level. Most studies agree that IL-1b is directly positively correlated to the degree of pain in patients with RC tendinopathy, especially when the examined sample is taken from the subacromial bursa. VEGF, and TNF-a have been related to shoulder pain preoperatively and TNF-a has also been linked with sleep disturbance. Further studies pointing to more biomarkers taken from the subacromial bursa or tendon directly relating to pain degree are warranted.

MicroRNA-29a Mitigates Subacromial Bursa Fibrosis in Rotator Cuff Lesion with Shoulder Stiffness.

Rotator cuff lesion with shoulder stiffness is a major cause of shoulder pain and motionlessness. Subacromial bursa fibrosis is a prominent pathological feature of the shoulder disorder. MicroRNA-29a (miR-29a) regulates fibrosis in various tissues; however, the miR-29a action to subacromial bursa fibrosis remains elusive. Here, we reveal that subacromial synovium in patients with rotator cuff tear with shoulder stiffness showed severe fibrosis, hypertrophy, and hyperangiogenesis histopathology along with significant increases in fibrotic matrices collagen (COL) 1A1, 3A1, and 4A1 and inflammatory cytokines, whereas miR-29a expression was downregulated. Supraspinatus and infraspinatus tenotomy-injured shoulders in transgenic mice overexpressing miR-29a showed mild swelling, vascularization, fibrosis, and regular gait profiles as compared to severe rotator cuff damage in wild-type mice. Treatment with miR-29a precursor compromised COL3A1 production and hypervascularization in injured shoulders. In vitro, gain of miR-29a function attenuated COL3A1 expression through binding to the 3'-untranslated region (3'-UTR) of COL3A1 in inflamed tenocytes, whereas silencing miR-29a increased the matrix expression. Taken together, miR-29a loss is correlated with subacromial bursa inflammation and fibrosis in rotator cuff tear with shoulder stiffness. miR-29a repressed subacromial bursa fibrosis through directly targeting COL3A1 mRNA, improving rotator cuff integrity and shoulder function. Collective analysis offers a new insight into the molecular mechanism underlying rotator cuff tear with shoulder stiffness. This study also highlights the remedial potential of miR-29a precursor for alleviating the shoulder disorder.

Epigallocatechin-3-gallate suppresses pain-related and proinflammatory mediators in the subacromial bursa in rotator cuff tendinopathy.

Rotator cuff tendinopathy is one of the leading causes of shoulder pain. However, the mechanisms involved in the development of rotator cuff tendinopathy pain are not fully understood. In this study, we first examined the histological features of subacromial bursa from patients with rotator cuff tendinopathy who had symptoms of pain, and investigated the expression of pain mediators, proinflammatory cytokines, metalloproteinases, growth factors, and alarmins in diseased tendon and bursa tissue by real-time PCR, western blot, and/or immunohistochemistry/immunofluorescence staining. Then we investigated whether epigallocatechin-3-gallate (EGCG) could reduce the expression of pain mediators and proinflammatory cytokines in human primary bursa cells and explored the paracrine effect of these EGCG-treated bursa cells on tenocytes in vitro. Neovascularization and infiltration of immune cells including monocytes/macrophages and mast cells were observed in diseased bursa tissue. Bursa from patients with pain had higher mRNA expression of pain mediators and proinflammatory cytokines, compared to the rotator cuff tendon of the same patients, as well as the bursa from asymptomatic patients. EGCG treatment significantly suppressed the interleukin 1 beta (IL-1ß)-induced elevation of mRNA expression of pain mediators, proinflammatory cytokines, and matrix metalloproteinases (MMPs) in bursa cells in vitro; conditioned medium from EGCG-treated bursa cells significantly reduced IL-1ß-induced expression in human primary tenocytes. Our study suggests that the subacromial bursa might serve as a local source of pain mediators and proinflammatory cytokines in rotator cuff tendinopathy. Moreover, EGCG treatment by primarily targeting the subacromial bursa may be a potential strategy to relieve rotator cuff tendinopathy-related pain and symptoms.

IL-1ß mediates NGF and COX-2 expression through transforming growth factor-activating kinase 1 in subacromial bursa cells derived from rotator cuff tear patients.

BACKGROUND: Increased interleukin (IL)-1ß expression in the subacromial bursa (SAB) is associated with severe pain in rotator cuff tears (RCTs). Additionally, transforming growth factor (TGF)-ß-activated kinase 1 (TAK1) is essential for cytokine-mediated cascades. TAK1 also regulates the expression of pain-associated molecules such as cycloxygenase-2 (COX-2) and nerve growth factor (NGF) in synovial fibroblasts; however, this regulation in the SAB is not fully understood. METHODS: SAB samples were harvested from 18 subjects with RCTs. The expression and localization of NGF and COX-2 was determined using polymerase chain reaction (PCR) analysis and immunohistochemistry. Regulation of COX-2 and NGF by IL-1ß in subacromial bursa cells (SABCs) was investigated by culturing and stimulating SABCs with vehicle control (culture medium), 50 ng/ml recombinant human IL-1ß (rhIL1-ß), 50 ng/ml rhIL-1ß and 10 µM celecoxib (COX-2 inhibitor), or 10 µM prostaglandin E2 (PGE2) for 24 h. The effects of TAK1 inhibition on rhIL-1ß stimulation were determined by culturing and treating SABCs with control, 50 ng/ml rhIL-1ß, or 50 ng/ml rhIL-1ß and 10 µM (5Z)-7-oxozeaenol (TAK1 inhibitor) for 24 h. NGF and COX-2 mRNA expression was monitored using quantitative PCR. RESULTS: COX-2 and NGF mRNA expression was observed in all SAB specimens. Immunohistochemical analysis showed that COX-2-positive cells were in the lining and sublining layers. NGF-positive cells were observed in the sublining layer. rhIL-1ß treatment significantly increased NGF and COX-2 mRNA levels compared with control cells. The COX-2 inhibitor did not suppress rhIL-1ß-induced NGF expression, and PGE2 stimulation did not alter NGF mRNA expression. In contrast, the TAK1 inhibitor significantly reduced rhIL-1ß-stimulated COX-2 and NGF mRNA expression. CONCLUSION: IL-1ß regulates the expression of NGF and COX-2, pain-related molecules in the SAB, through TAK1. Therefore, TAK1 may be one potential therapeutic target for reducing pain in patients with RCTs.

Increased expression of type 1 cannabinoid (CB1) receptor among patients with rotator cuff lesions and shoulder stiffness.

BACKGROUND: Shoulder stiffness is a disease manifested by pain, limited range of motion, and functional disability. The inflammatory and fibrosis processes play a substantial role in the pathogenesis of shoulder stiffness. The CB1 receptor has been recognized to mediate the processes of pathologic fibrosis. This study investigated the role of the CB1 pathway in pathogenesis of rotator cuff lesions with shoulder stiffness. METHODS: All of the patients undergoing repair surgery for rotator cuff lesions were recruited and subcategorized into subjects with and without shoulder stiffness. Reverse transcription-polymerase chain reaction assay was used to evaluate the expression level of CB1 and interleukin 1ß (IL-1ß) in the subacromial bursae, and enzyme-linked immunosorbent assay was used to measure the concentration of CB1 and IL-1ß in the subacromial fluid. Tenocytes treated with CB1 agonists and antagonists were also studied for the relationship of CB1 and the inflammatory cytokine IL-1ß. RESULTS: The patients with shoulder stiffness had higher messenger RNA (mRNA) expression (P = .040) and immunohistochemistry staining (P < .001) of CB1 in the subacromial bursa and higher CB1 concentration in the subacromial fluid (P = .008). Tenocytes treated with the CB1 agonist WIN 55,212-2 and antagonist AM251 showed increased expression of IL-1ß mRNA (P = .049) and suppressed expression of IL-1ß mRNA (P = .001), respectively. DISCUSSION: The CB1 pathway is involved in the pathogenesis of shoulder stiffness. It may be a promising target for the treatment of rotator cuff lesions with shoulder stiffness.

RNA­sequence analysis of samples from patients with idiopathic adhesive capsulitis.

The present study aimed to investigate idiopathic adhesive capsulitis (frozen shoulder), to gain insights on its pathogenesis, diagnosis and therapeutic targets. Using RNA­sequencing (seq), the present study investigated differentially expressed genes (DEGs) in five samples from five idiopathic adhesive capsulitis patients and two samples from two acromioclavicular dislocation patients, without idiopathic adhesive capsulitis. The DEGs were analyzed using the following tools: Gene Ontology enrichment analysis, Kyoto Encyclopedia of Genes and Genomes pathways analysis and protein­protein interaction analysis. A total of 188 DEGs were identified and it was observed that 150 of these were upregulated and 38 were downregulated. It was hypothesized that various nutrient associated proteins may be associated with idiopathic adhesive capsulitis. The Matrix metalloproteinase family of proteins (MMPs), may exhibit a key role in the formation of abnormal collagen cross­links. Overall, the comprehensive and detailed information collected in the present study, regarding idiopathic adhesive capsulitis, may provide a foundation on which in­depth follow­up experiments may be based, aimed at identifying novel strategies for treatment of this disease.

Landmark-Guided and Ultrasound-Guided Approaches for Trochanteric Bursa Injection: A Cadaveric Study.

BACKGROUND: Trochanteric bursa (TB) injection with local anesthetic and corticosteroid is a treatment for patients suffering from greater trochanteric pain syndrome. Both landmark (LM)-guided and ultrasound (US)-guided methods have been used, but their accuracies have not been determined. This study examined the accuracy of these injections with cadaveric dissection. METHODS: Twenty-four hip specimens were randomized to receive TB injections with methylene blue under either LM-guided or US-guided approach. After dissection, the locations of the dye were classified into 3 categories: intrabursal, extrabursal, or combined intrabursal and extrabursal. The presence of dye in the intrabursal space with or without extrabursal leak was considered a successful injection. Accuracy was defined as the percentage of successful injection. RESULTS: The accuracies of the LM-guided and US-guided injection were 0.67 (95% confidence interval 0.35-0.90) and 0.92 (95% confidence interval 0.62-1.00), respectively, with no significant difference. CONCLUSIONS: This is the first cadaveric study examining the accuracy of both the US-guided and LM-guided techniques for TB injection. Future clinical studies are required to compare the outcomes of LM-guided and US-guided greater trochanteric pain syndrome injection.

Increased substance P expression in the trochanteric bursa of patients with greater trochanteric pain syndrome.

Greater trochanteric pain syndrome (GTPS) is a pathology that can involve the trochanteric bursa or the tendons which attach to the greater trochanter. To clarify the potential importance of bursa versus tendon pathology and of substance P (SP) in contributing to pain in this condition tendon and bursa tissue biopsies were obtained from 34 patients with GTPS and 29 control subjects. Specimens were evaluated via light microscopy for histopathological and morphological differences, as well as using immunohistochemistry for macrophages (CD68), inflammatory cells (CD45) and SP. Bursa [stroma score, mean (SD): 4.18 (1.65) vs. 2.53 (1.61), p = 0.051] and tendon [Bonar score, mean (SD): GTPS mean (SD) 12.65 (2.0), control (10.43 (4.84), p = 0.04] from subjects with GTPS demonstrated more extensive signs of pathology than specimens from control subjects. There was a significantly greater presence of SP in the bursa (frequency: 9/12 vs. 6/16, p = 0.047), but not in the tendon (8/12 vs. 8/15, p = 0.484) of subjects with GTPS compared to controls. An increased presence of SP in the trochanteric bursa may be related to the pain associated with GTPS.

The possible role of the transcription factor nuclear factor-κB on evolution of rotator cuff tear and on mechanisms of cuff tendon healing.

BACKGROUND: We verified if the nuclear factor-κB (NF-κB) was present on the margins of rotator cuff tears (RCTs). Because NF-κB regulates apoptosis and stimulates neoangiogenesis, we hypothesized that NF-κB has a role in the evolution of RCT and in possible mechanisms of RCT healing. MATERIALS AND METHODS: Samples from tear margins, subacromial bursa, and healthy subscapular tendons were excised during arthroscopic treatment of patients with posterosuperior RCT. Sections were cut and stained with hematoxylin and eosin for morphologic evaluation and used for immunohistochemical analysis with NF-κB p65 antibody. RESULTS: The presence of NF-κB in the RCT margins and subacromial bursa increases with increasing tear size. NF-κB is also present in the subscapularis tendon of patients with large and massive RCT. Analogously, we observed that neoangiogenesis grows with increasing RCT size and is always present in the subscapularis tendon independently from RCT size. Statistical analysis indicates that NF-κB and neoangiogenesis are correlated, regardless of the dimension of the RCT. CONCLUSIONS: This is the first study that identifies the association between activated NF-κB and RCT. Activated NF-κB on the margins of RCT increases with increasing tear size. We hypothesized a series of possible causes responsible for NF-κB activation; however, we believe that activation is due to tissue hypoxia. Activated p65 directly stimulates neoangiogenesis, but the same factors that regulate NF-κB activation might also act as neoangiogenesis inductors.

Inflammatory cytokines are overexpressed in the subacromial bursa of frozen shoulder.

BACKGROUND: Frozen shoulder is a debilitating condition characterized by gradual loss of glenohumeral motion with chronic inflammation and capsular fibrosis. Yet its pathogenesis remains largely unknown. We hypothesized that the subacromial bursa may be responsible for the pathogenesis of frozen shoulder by producing inflammatory cytokines. MATERIALS AND METHODS: We obtained joint capsules and subacromial bursae from 14 patients with idiopathic frozen shoulder and from 7 control subjects to determine the expression levels of interleukin (IL) 1α, IL-1ß, IL-6, tumor necrosis factor α (TNF-α), cyclooxygenase (COX) 1, and COX-2 by real-time reverse transcriptase-polymerase chain reaction, immunohistochemistry, and enzyme-linked immunosorbent assay. RESULTS: IL-1α, IL-1ß, TNF-α, COX-1, and COX-2 were expressed at significantly high levels in the joint capsules of the frozen shoulder group compared with those of the control group. Intriguingly, IL-1α, TNF-α, and COX-2 were also expressed at significantly high levels in the subacromial bursae of the frozen shoulder group compared with those of the control group. Immunohistochemical analysis showed increased expression of COX-2 in both the joint capsules and subacromial bursae of the frozen shoulder group. CONCLUSIONS: These findings imply that elevated levels of inflammatory cytokines in the subacromial bursa may be associated with the pathogenesis of inflammation evolving into fibrosis.

The arthritis severity locus Cia5a regulates the expression of inflammatory mediators including Syk pathway genes and proteases in pristane-induced arthritis.

BACKGROUND: Cia5a is a locus on rat chromosome 10 that regulates disease severity and joint damage in two models of rheumatoid arthritis, collagen- and pristane-induced arthritis (PIA). In this study, we aimed to identify cellular and molecular processes regulated by Cia5a using microarray-based gene expression analysis of synovial tissues from MHC identical DA (severe erosive disease) and DA.F344(Cia5a) congenics (mild non-erosive disease) rats. RESULTS: Synovial tissues from six DA and eight DA.F344(Cia5a) rats were analyzed 21 days after the induction of PIA using the Illumina RatRef-12 BeadChip (21,922 genes) and selected data confirmed with qPCR. There was a significantly increased expression of pro-inflammatory mediators such as Il1b (5-fold), Il18 (3.9-fold), Cxcl1 (10-fold), Cxcl13 (7.5-fold) and Ccl7 (7.9-fold), and proteases like Mmp3 (23-fold), Mmp9 (32-fold), Mmp14 (4.4-fold) and cathepsins in synovial tissues from DA, with reciprocally reduced levels in congenics. mRNA levels of 47 members of the Spleen Tyrosine Kinase (Syk) pathway were significantly increased in DA synovial tissues compared with DA.F344(Cia5a), and included Syk (5.4-fold), Syk-activating receptors and interacting proteins, and genes regulated by Syk such as NFkB, and NAPDH oxidase complex genes. Nuclear receptors (NR) such as Rxrg, Pparg and Rev-erba were increased in the protected congenics, and so was the anti-inflammatory NR-target gene Scd1 (54-fold increase). Tnn (72-fold decrease) was the gene most significantly increased in DA. CONCLUSIONS: Analyses of gene expression in synovial tissues revealed that the arthritis severity locus Cia5a regulates the expression of key mediators of inflammation and joint damage, as well as the expression of members of the Syk pathway. This expression pattern correlates with disease severity and joint damage and along with the gene accounting for Cia5a could become a useful biomarker to identify patients at increased risk for severe and erosive disease. The identification of the gene accounting for Cia5a has the potential to generate a new and important target for therapy and prognosis.

Steroid diffusion into the navicular bursa occurs in horses affected by palmar foot pain.

Palmar foot pain is frequently treated by steroid injections into the distal interphalangeal joint (DIPJ) in the anticipation that the steroid will diffuse to the navicular bursa and palmar foot structures. The object of this study was to determine if triamcinolone acetonide (TA) would in fact be able to locally diffuse from the DIPJ into the navicular bursa in horses affected by palmar foot pain. Both forelimb DIPJs (nine horses) were injected with 10 mg of TA. Navicular bursa fluid samples, both forelimb and one hind limb (systemic control), were analysed for TA with high-performance liquid chromatography/tandem mass spectrometry (HPLC-MS/MS) six hours later. Foot radiographs were graded (0-4) on severity of changes. Forelimb navicular bursa TA concentrations (mean±sd log(10), 3.20±0.56) were significantly higher than systemic control concentrations (mean±sd log(10), 1.89±0.3) (P<0.0001). Horses with a radiographic grade of >2 were four times as likely to have TA log(10) concentrations less than 3.2 (158.49 ng/ml). TA locally diffused from the DIPJ into the navicular bursa in horses affected by palmar foot pain; TA concentrations decreased as radiographic severity increased.

Apoptosis signal-regulating kinase 1 is mediated in TNF-α-induced CCL2 expression in human synovial fibroblasts.

Tumor necrosis factor-α (TNF-α), a pro-inflammatory cytokine with a critical role in osteoarthritis (OA), was primarily produced by monocytes/macrophages and plays a crucial role in the inflammatory response. Here, we investigated the intracellular signaling pathways involved in TNF-α-induced monocyte chemoattractant protein 1 (MCP-1)/CCL2 expression in human synovial fibroblast cells. Stimulation of synovial fibroblasts (OASF) with TNF-α induced concentration- and time-dependent increases in CCL2 expression. TNF-α-mediated CCL2 production was attenuated by TNFR1 monoclonal antibody (Ab). Pretreatment with an apoptosis signal-regulating kinase 1 (ASK1) inhibitor (thioredoxin), JNK inhibitor (SP600125), p38 inhibitor (SB203580), or AP-1 inhibitor (curcumin or tanshinone IIA) also blocked the potentiating action of TNF-α. Stimulation of cells with TNF-α enhanced ASK1, JNK, and p38 activation. Treatment of OASF with TNF-α also increased the accumulation of phosphorylated c-Jun in the nucleus, AP-1-luciferase activity, and c-Jun binding to the AP-1 element on the CCL2 promoter. TNF-α-mediated AP-1-luciferase activity and c-Jun binding to the AP-1 element were inhibited by TNFR1 Ab, thioredoxin, SP600125, and SB203580. Our results suggest that the interaction between TNF-α and TNFR1 increases CCL2 expression in human synovial fibroblasts via the ASK1, JNK/p38, c-Jun, and AP-1 signaling pathway.

Can vagus nerve stimulation halt or ameliorate rheumatoid arthritis and lupus?

Acetylcholine, the principal vagus neurotransmitter, inhibits inflammation by suppressing the production of pro-inflammatory cytokines through a mechanism dependent on the α7 nicotinic acetylcholine receptor subunit (alpha7nAChR) that explains why vagus nerve stimulation is anti-inflammatory in nature. Strong expression of alpha7nAChR in the synovium of rheumatoid arthritis and psoriatic arthritis patients was detected. Peripheral macrophages and synovial fibroblasts respond in vitro to specific alpha7nAChR cholinergic stimulation with potent inhibition of proinflammatory cytokines. Fibroblasts balance inflammatory mechanisms and arthritis development through feedback cholinergic stimulation by nearby immune cells. Collagen induced arthritis in alpha7nAChR(-/-) mice was significantly severe and showed increased synovial inflammation and joint destruction compared to the wild-type mice. Similar to vagal nerve stimulation and alpha7nAChR agonists, polyunsaturated fatty acids: eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) also suppress inflammation. In view of their similar anti-inflammatory actions, it is proposed that vagal nerve stimulation, alpha7nAChR agonists and EPA and DHA may augment the formation of anti-inflammatory lipid molecules: lipoxins, resolvins, protectins and maresins. This implies that therapies directed at regulation of the cholinergic and alpha7nAChR mediated mechanisms and enhancing the formation of lipoxins, resolvins, protectins and maresins may halt and/or ameliorate rheumatoid arthritis, lupus and other rheumatological conditions.

Expression of IL-10 family cytokines in rheumatoid arthritis: elevated levels of IL-19 in the joints.

OBJECTIVES: Interleukin (IL)-10 functions as an anti-inflammatory cytokine in rheumatoid arthritis (RA). New IL-10 family cytokines IL-19, IL-20, IL-22, IL-24, and IL-26 have recently been discovered. Information concerning the expression and function of these cytokines in autoimmune diseases is currently limited. The aim of this study was to investigate their expression in RA. METHODS: mRNA levels of the cytokines were studied using quantitative reverse transcriptase polymerase chain reaction (RT-PCR). Peripheral blood (PB) and synovial fluid (SF) mononuclear cells (MCs), purified T cells, and monocytes/macrophages from RA patients and healthy volunteers, and synovial tissues from patients with RA or osteoarthritis (OA), were examined. The expression of IL-19 protein in T cells and monocytes/macrophages was studied by flow cytometry. RESULTS: IL-10 and IL-19 mRNA levels were significantly elevated in SFMCs from patients with RA compared with PBMCs from RA patients or healthy volunteers. IL-20 and IL-22 mRNA levels were also upregulated in RA SFMCs but their level of expression was lower than that of IL-10 or IL-19. Importantly, synovial tissue IL-19 levels in RA were increased when compared with OA. IL-19 expression was upregulated in both T cells and macrophages derived from patients with RA. IL-1beta increased IL-19 levels in PBMCs, suggesting that elevated levels of IL-1 in RA joints may contribute to upregulated IL-19 expression. CONCLUSIONS: The majority of the IL-10 family cytokines are expressed in RA. IL-19 demonstrated the highest expression in rheumatoid joints, and could thus be involved in the regulation of synovial inflammation in RA.

Evaluation of the diffusion of corticosteroids between the distal interphalangeal joint and navicular bursa in horses.

OBJECTIVE: To determine whether clinically effective concentrations of methylprednisolone or triamcinolone can be achieved in the navicular bursa after injection of methylprednisolone acetate (MPA) or triamcinolone acetonide (TA) into the distal interphalangeal joint (DIPJ) and whether clinically effective concentrations of these drugs can be achieved in the DIPJ after injecting the navicular bursa with the same doses of MPA or TA. ANIMALS: 32 healthy horses. PROCEDURES: Horses in groups 1 through 4 received 40 mg of MPA in the DIPJ, 10 mg of TA in the DIPJ, 40 mg of MPA in the navicular bursa, and 10 mg of TA in the navicular bursa, respectively. Concentrations of corticosteroids that diffused into the adjacent synovial structure were determined. RESULTS: For group 1, injection of MPA into the DIPJ yielded a mean +/- SD concentration of 0.24 +/- 0.072 microg of methylprednisolone/mL in the navicular bursa. For group 2, injection of TA into the DIPJ yielded 0.124 +/- 0.075 microg of triamcinolone/mL in the navicular bursa. For group 3, injection of MPA into the navicular bursa yielded 0.05 +/- 0.012 microg of methylprednisolone/mL in the DIPJ. For group 4, injection of TA into the navicular bursa yielded 0.091 +/- 0.026 microg of triamcinolone/mL in the DIPJ. CONCLUSIONS AND CLINICAL RELEVANCE: A clinically effective concentration of methylprednisolone or triamcinolone diffused between the DIPJ and navicular bursa after intra-articular or intrabursal injection, which would justify injection of the DIPJ with MPA or TA to ameliorate inflammation of the navicular bursa.