Intervertebral disc (IVD) degeneration is a major cause of low back pain (LBP). Following disc injury, nerve growth factor (NGF) concentrations rise in IVDs, and anti-NGF therapy has been shown to ...attenuate LBP in humans. Increased levels of tumor necrosis factor-α (TNF-α) and transforming growth factor-β (TGF-β) in degenerative IVDs and in in vitro studies suggest that these factors promote NGF production. However, whether these factors regulate NGF in vivo remains unclear. Thus, we studied NGF regulation in a mouse model of IVD injury.
After inducing IVD injury, we examined mRNA levels of Tnfa, Tgfb, and Ngf in IVDs from control and IVD-injured mice across 7 days. To do this, we used magnetic cell separation to isolate CD11b ( +) (macrophage-rich) and CD11b (-) (IVD cell-rich) cell fractions from injured IVDs. To study the effect of TNF-α on Ngf expression, we examined Ngf expression in injured IVDs from C57BL/6 J and Tnfa-knockout (KO) mice (C57BL/6 J background). To study the effect of TGF-β on Ngf expression, C57/BL6J mice were given an intraperitoneal injection of either the TGF-β inhibitor SB431542 or DMSO solution (vehicle) one and two days before harvesting IVDs.
mRNA expression of Tnfa, Tgfb, and Ngf was significantly increased in injured IVDs. Tnfa was predominantly expressed in the CD11b ( +) fraction, and Tgfb in the CD11b (-) fraction. Ngf expression was comparable between CD11b ( +) and CD11b (-) fractions, and between wild-type and Tnfa-KO mice at post-injury day (PID) 1, 3, and 7. SB431542 suppressed TGF-β-mediated Ngf expression and NGF production in vitro. Further, administration of SB431542 significantly reduced Ngf expression in IVDs such that levels were below those observed in vehicle-treated animals at PID3 and PID7.
A TGF-β inhibitor reduced Ngf expression in a mouse model of IVD injury, suggesting that TGF-β may regulate NGF expression in vivo.
Nerve growth factor (NGF) plays a key role in osteoarthritic pain and low back pain. Rotator cuff tear (RCT) is often associated with severe shoulder pain. However, the role of NGF in RCT remains to ...be fully understood.
Rats were divided into sham and RCT groups. The rotator cuff was harvested from the sham and RCT groups on various days for reverse transcription-polymerase chain reaction analysis of Tnfa, Ngf, Il1b, and Cox2 expression. Rotator cuffs from the sham and RCT groups were also harvested at 1 and 14 days for enzyme-linked immunosorbent assay and immunohistochemistry to assess NGF protein levels and localization. Rotator cuff–derived cells were stimulated with rat recombinant tumor necrosis factor (TNF)-α to investigate the involvement of TNF-α in the regulation of NGF expression.
Tnfa and Ngf messenger RNA levels increased within 1 day in the RCT group. Notably, Tnfa and Ngf upregulation persisted for up to 56 days after the RCT surgery, while Il1b and Cox2 expression was significantly reduced. NGF levels in the RCT group were significantly higher than those in the sham operation group on days 1 and 14. Certain inflammatory cells and synovial-like cells lining the surface of the laminated tears were NGF-positive on days 1 and 14, respectively. Ngf messenger RNA levels increased significantly in rotator cuff–derived cells after TNF-α stimulation.
NGF levels are continuously elevated in RCT, which is mainly regulated by TNF-α. NGF may thus represent a potential target for therapies that modulate RCT pain.
Introduction
Studies have identified the presence of M1 and M2 macrophages (Mϕ) in injured intervertebral discs (IVDs). However, the origin and polarization-regulatory factor of M2 Mϕ are not fully ...understood. TGF-β is a regulatory factor for M2 polarization in several tissues. Here, we investigated the source of M2 Mϕ and the role of TGF-β on M2 polarization using a mice disc-puncture injury model.
Methods
To investigate the origin of M2 macrophages, 30 GFP chimeric mice were created by bone marrow transplantation. IVDs were obtained from both groups on pre-puncture (control) and post-puncture days 1, 3, 7, and 14 and CD86 (M1 marker)- and CD206 (M2 marker)-positive cells evaluated by flow cytometry (n = 5 at each time point). To investigate the role of TGF-β on M2 polarization, TGF-β inhibitor (SB431542) was also injected on post-puncture days (PPD) 5 and 6 and CD206 expression was evaluated on day 7 by flow cytometry (n = 5) and real time PCR (n = 10).
Results
The proportion of CD86+ Mϕ within the GFP+ population was significantly increased at PPD 1, 3, 7, and 14 compared to control. CD206-positive cells in GFP-populations were significantly increased on PPD 7 and 14. In addition, the percentage of CD206-positive cells was significantly higher in GFP-populations than in GFP+ populations. TGF-β inhibitor reduced CD206-positive cells and Cd206 expression at 7 days after puncture.
Conclusion
Our findings suggest that M2 Mϕ following IVD injury may originate from resident Mϕ. TGF-β is a key factor for M2 polarization of macrophages following IVD injury.
Animal studies suggest that pain-related-molecule upregulation in degenerated intervertebral discs (IVDs) potentially leads to low back pain (LBP). We hypothesized that IVD mechanical stress and ...axial loading contribute to discogenic LBP's pathomechanism. This study aimed to elucidate the relationships among the clinical findings, radiographical findings, and pain-related-molecule expression in human degenerated IVDs. We harvested degenerated-IVD samples from 35 patients during spinal interbody fusion surgery. Pain-related molecules including tumor necrosis factor alpha (TNF-alpha), interleukin (IL)-6, calcitonin gene-related peptide (CGRP), microsomal prostaglandin E synthase-1 (mPGES1), and nerve growth factor (NGF) were determined. We also recorded preoperative clinical findings including body mass index (BMI), Oswestry Disability Index (ODI), and radiographical findings including the vacuum phenomenon (VP) and spinal instability. Furthermore, we compared pain-related-molecule expression between the VP (-) and (+) groups. BMI was significantly correlated with the ODI, CGRP, and mPGES-1 levels. In the VP (+) group, mPGES-1 levels were significantly higher than in the VP (-) group. Additionally, CGRP and mPGES-1 were significantly correlated. Axial loading and mechanical stress correlated with CGRP and mPGES-1 expression and not with inflammatory cytokine or NGF expression. Therefore, axial loading and mechanical stress upregulate CGRP and mPGES-1 in human degenerated IVDs, potentially leading to chronic discogenic LBP.
Increased interleukin (IL)-1β expression in the subacromial bursa (SAB) is associated with severe pain in rotator cuff tears (RCTs). Additionally, transforming growth factor (TGF)-β-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.
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-1β in subacromial bursa cells (SABCs) was investigated by culturing and stimulating SABCs with vehicle control (culture medium), 50 ng/ml recombinant human IL-1β (rhIL1-β), 50 ng/ml rhIL-1β and 10 μM celecoxib (COX-2 inhibitor), or 10 μM prostaglandin E2 (PGE2) for 24 h. The effects of TAK1 inhibition on rhIL-1β stimulation were determined by culturing and treating SABCs with control, 50 ng/ml rhIL-1β, or 50 ng/ml rhIL-1β and 10 μM (5Z)-7-oxozeaenol (TAK1 inhibitor) for 24 h. NGF and COX-2 mRNA expression was monitored using quantitative PCR.
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-1β treatment significantly increased NGF and COX-2 mRNA levels compared with control cells. The COX-2 inhibitor did not suppress rhIL-1β-induced NGF expression, and PGE2 stimulation did not alter NGF mRNA expression. In contrast, the TAK1 inhibitor significantly reduced rhIL-1β-stimulated COX-2 and NGF mRNA expression.
IL-1β 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.
Epidemiological studies have reported a positive association between hypercholesterolemia and shoulder disease. Previous studies have focused on the effect of hypercholesterolemia on tendinopathy. ...Moreover, hypercholesterolemia has also been linked to joint pathology in the knee and hand. However, the effect of hyperlipidemia on glenohumeral joint remain unclear. A hypercholesterolemic condition has been reported to alter levels of A Disintegrin and Metalloprotease with Thrombospondin Motifs (ADAMTSs) and matrix metalloproteases (MMPs) in synovium of the knee joint. Here, we evaluated the mRNA expression of ADAMTSs and MMPs in the glenohumeral synovium of patients with and without hypercholesterolemia.
Study participants were 73 patients who underwent arthroscopic rotator cuff repair for degenerative rotator cuff tears. They were divided into two groups according to total cholesterol (TC) and triglyceride levels. Synovial membrane samples were harvested at the rotator interval during surgery, and mRNA expression levels of the aggrecanases ADAM-TS4 and ADAM-TS5 and MMPs (MMP-1, 3, 9, and 13) were analyzed quantitatively.
ADAM-TS5 and MMP1 mRNA levels were significantly higher in the high TC group than in the low TC group (P = 0.023 and P = 0.025, respectively). In contrast, no significant differences were observed in ADAMTS4 or MMPs 3, 9, and 13 (ADAMTS4, P = 0.547; MMP3, P = 0.55; MMP9, P = 0.521; and MMP13, P = 0.785).
Hypercholesterolemia may alter MMP1 and ADAMTS5 expression in the synovium of the glenohumeral joint.
The rotator cuff undergoes natural degeneration with age, leading to age-related rotator cuff tear; however, the precise mechanism remains unclear. Transforming growth factor-beta (TGF-β) ...concentrations rise with age and TGF-β contributes to the pathophysiology of skeletal muscle. TGF-β has also been shown to suppress expression of the myokine, apelin, in skin fibroblasts. We hypothesized that TGF-β expression in the rotator cuff changes with age and regulates apelin expression, thereby contributing to rotator cuff degeneration.
We used quantitative reverse-transcription polymerase chain reaction (Q-RT-PCR) to measure the expression of apelin and tendon-related genes (Tnmd, Col1a1, and Col3a1) in the rotator cuff of young (12 weeks), adult (24 weeks), and old (48 weeks) rats. Using Q-RT-PCR and enzyme-linked immunosorbent assay, we also measured Tgfb mRNA and TGF-β protein levels, respectively. Furthermore, we used Q-RT-PCR to measure apelin mRNA levels in rotator cuff-derived cells after treatment with 0 (control) and 10 ng/mL recombinant TGF-β.
Apelin mRNA levels were significantly lower in old compared to young and adult rats. Similarly, tendon-related genes, Tnmd, Col1a1, and Col3a1, were significantly lower in adult and old rats than young rats. In contrast, Tgfb mRNA and TGF-β protein were significantly higher in old compared to young rats. Stimulation with exogenous TGF-β significantly decreased Apelin mRNA expression compared to control.
TGF-β regulates apelin expression in the rotator cuff and may play a key role in the degenerative pathology of the rotator cuff with age.
Background
Rotator cuff tears (RCTs) are often associated with severe shoulder pain. Non-steroidal anti-inflammatory drugs, not recommended for long-term use, do not effectively manage RCT-induced ...pain, resulting in reduced quality of life. To improve management, a better understanding of the fundamental properties of RCT pain is needed. Here, we aimed to compare the expression levels of nerve growth factor (NGF) and cyclooxygenase-2 (COX-2) mRNA in the synovial tissues of patients with RCT-induced pain and patients with non-painful recurrent shoulder dislocation (RSD).
Methods
The study included 32 patients with RCT who underwent arthroscopic rotator cuff repair and 28 patients with non-painful RSD who underwent arthroscopic Bankart repair. Synovial tissue samples were harvested from subacromial bursa and rotator interval of RCT patients and from the rotator interval of RSD patients. Samples were analyzed quantitatively expression levels for NGF and COX2 mRNA and NGF protein.
Results
NGF mRNA and protein levels were significantly higher in the rotator interval of RCT patients than in the rotator interval of RSD patients (p = 0.0017, p = 0.012, respectively), while COX2 mRNA levels did not differ significantly between the two patient groups. In RCT patients, COX2 mRNA was more highly expressed in the rotator interval than in the subacromial bursa (p = 0.038), whereas the mRNA and protein levels of NGF did not differ between the two tissues. The expression of NGF mRNA in the synovium of the rotator interval was significantly correlated with the numeric rating scale of pain (ρ = 0.38, p = 0.004).
Conclusion
NGF mRNA and protein levels were elevated in patients with painful RCT compared with those in patients with non-painful RSD, whereas COX-2 levels were comparable in the two patient groups. These findings provide insights into novel potential strategies for clinical management of RCT.
The purpose of this study to compare glenohumeral joint motion during active shoulder axial rotation between subacromial impingement syndrome (SIS) shoulders and asymptomatic shoulders using ...cine-magnetic resonance imaging (cine-MRI). Measurement of glenohumeral joint motion via manual intervention does not assess the usual glenohumeral joint motion, and the glenoid surface cannot be confirmed manually. However, cine-MRI can produce clear images of glenohumeral joint rotation. Therefore, we sought to measure the active ROM of the glenohumeral rotation using cine-MRI.
Seventy-three shoulders in 42 asymptomatic volunteers and 110 SIS shoulders in 103 consecutive patients were included in this study. We evaluated 36 matched pairs (72 shoulders in total) adjusting for baseline characteristics with propensity score matching method. The patients underwent cine-MRI during axial rotation of the adducted arm. During imaging, participants rotated their shoulder from the maximum internal rotation to the maximum external rotation over the first 10 s and then back to the maximum internal rotation over the subsequent 10 s. We assessed internal/external rotation, and compared the asymptomatic and SIS shoulders in this regard. Evaluation of rotation angles was performed on a series of axial images through the humeral head center.
The mean internal rotation angles of the asymptomatic and patient groups were 55° ± 10° and 41° ± 23°, respectively, (P = .002; 95% Confidence Interval CI, 51-58 vs 33-49); the mean external rotation angles were 47° ± 15° and 21° ± 25°, respectively, (P < .001; CI, 42-52 vs 13-29).
Compared to asymptomatic shoulders, SIS shoulders showed significantly restricted glenohumeral rotation as determined by cine-MRI. Our results suggested that the significant limitation of active glenohumeral rotation might be associated with rotator cuff dysfunction.
Strengthening the infraspinatus is important in shoulder rehabilitation. Changes in infraspinatus activity with changing load and position have not been quantified. We sought to determine the most ...appropriate load and posture for early infraspinatus strengthening by assessing for changes in electromyographic activity in the healthy infraspinatus and other shoulder girdle muscles during isometric external rotational exercise under different loads with the shoulder adducted in the supine and seated positions.
Sixteen healthy adults (30 shoulders) performed isometric shoulder external rotation in the sitting and supine positions, starting with the shoulder and forearm in neutral position and the elbow flexed 90°. Loads (0.5 kg, 1 kg, and 2 kg) were applied at rest. We assessed the infraspinatus, upper trapezius, posterior deltoid, and biceps brachii. For analysis, we used the mean percentage of maximum voluntary muscle contraction (%MVC) value measured during each isometric contraction divided by the maximum voluntary muscle contraction (MVC) of each muscle.
In the infraspinatus and posterior deltoid, significant interaction was observed between body position and load. Compared to the sitting position, an increase in activity in the supine position was attenuated as load increased, especially at 2 kg. The supine values of the upper trapezius and biceps brachii were always significantly lower than those in the sitting position regardless of load.
The activity of the infraspinatus can be increased gradually during rehabilitation by beginning in the supine position, which assures low activity of the upper trapezius and biceps brachii. Exercise with the shoulder adducted in the supine position can strengthen the infraspinatus gradually and avoid compensatory mobility.
Level 3.
PDF
