Repeated Electroacupuncture Persistently Elevates Adenosine and Ameliorates Collagen-Induced Arthritis in Rats

Effect of acupuncture on ischaemic stroke in patients with rheumatoid arthritis: a nationwide propensity score-matched study

OBJECTIVE

To demonstrate that acupuncture is beneficial for decreasing the risk of ischaemic stroke in patients with rheumatoid arthritis (RA).

DESIGN

A propensity score-matched cohort study.

SETTING

A nationwide population-based study.

PARTICIPANTS

Patients with RA diagnosed between 1 January 1997 and 31 December 2010, through the National Health Insurance Research Database in Taiwan.

INTERVENTIONS

Patients who were administered acupuncture therapy from the initial date of RA diagnosis to 31 December 2010 were included in the acupuncture cohort. Patients who did not receive acupuncture treatment during the same time interval constituted the no-acupuncture cohort.

PRIMARY OUTCOME MEASURES

A Cox regression model was used to adjust for age, sex, comorbidities, and types of drugs used. We compared the subhazard ratios (SHRs) of ischaemic stroke between these two cohorts through competing-risks regression models.

RESULTS

After 1:1 propensity score matching, a total of 23 226 patients with newly diagnosed RA were equally subgrouped into acupuncture cohort or no-acupuncture cohort according to their use of acupuncture. The basic characteristics of these patients were similar. A lower cumulative incidence of ischaemic stroke was found in the acupuncture cohort (log-rank test, p<0.001; immortal time (period from initial diagnosis of RA to index date) 1065 days; mean number of acupuncture visits 9.83. In the end, 341 patients in the acupuncture cohort (5.95 per 1000 person-years) and 605 patients in the no-acupuncture cohort (12.4 per 1000 person-years) experienced ischaemic stroke (adjusted SHR 0.57, 95% CI 0.50 to 0.65). The advantage of lowering ischaemic stroke incidence through acupuncture therapy in RA patients was independent of sex, age, types of drugs used, and comorbidities.

CONCLUSIONS

This study showed the beneficial effect of acupuncture in reducing the incidence of ischaemic stroke in patients with RA.

The role of purinergic signaling in acupuncture-mediated relief of neuropathic and inflammatory pain

Acupuncture is a traditional medicinal practice in China that has been increasingly recognized in other countries in recent decades. Notably, several reports have demonstrated that acupuncture can effectively aid in pain management. However, the analgesic mechanisms through which acupuncture provides such benefits remain poorly understood. Purinergic signaling, which is mediated by purine nucleotides and purinergic receptors, has been proposed to play a central role in acupuncture analgesia. On the one hand, acupuncture affects the transmission of nociception by increasing adenosine triphosphate dephosphorylation and thereby decreasing downstream P2X3, P2X4, and P2X7 receptors signaling activity, regulating the levels of inflammatory factors, neurotrophic factors, and synapsin I. On the other hand, acupuncture exerts analgesic effects by promoting the production of adenosine, enhancing the expression of downstream adenosine A1 and A2A receptors, and regulating downstream inflammatory factors or synaptic plasticity. Together, this systematic overview of the field provides a sound, evidence-based foundation for future research focused on the application of acupuncture as a means of relieving pain.

Electroacupuncture stimulating Zusanli (ST36), Sanyinjiao (SP6) in mice with collagen-induced arthritis leads to adenosine A2A receptor-mediated alteration of p38α mitogen-activated protein kinase signaling and inhibition of osteoclastogenesis

OBJECTIVE

To observe the effect of electroacupuncture (EA) stimulating Zusanli (ST36), Sanyinjiao (SP6) on inhibition of osteoclastogenesis and the role of the adenosine A2A receptor (A2AR) and the p38α Mitogen-Activated Protein Kinase (MAPK) signaling pathway in mediating this effect.

METHODS

Mice with collagen induced arthritis (CIA) received different treatments. Immunohistochemistry and western blotting were used to determine the levels of multiple signaling molecules in these joints [receptor activator of nuclear transcription factor-κB (NF-κB) ligand (RANKL), receptor activator of NF-κB (RANK), tumor necrosis factor receptor associated factor 6 (TRAF6), p38α, NF-κB, and nuclear factor of activated T cells C1 (NFATc1)]. Osteoclasts were identified using tartrate-resistant acid phosphatase (TRAP) staining.

RESULTS

The immunohistochemistry results indicated upregulation of p38α, NF-κB, and NFATc1 in the CIA-control and CIA-EA-SCH58261 groups, but reduced levels in the CIA-EA group. Western blotting indicated upregulation of RANKL, RANK, TRAF6, p38α, NF-κB, and NFATc1 in the CIA-control and CIA-EA-SCH58261 groups, but reduced expression in the CIA-EA group. Osteoclasts were more abundant in the CIA-control and CIA-EA-SCH58261 groups than in the CIA-EA group.

CONCLUSIONS

EA treatment enhanced the A2AR activity and inhibited osteoclast formation by inhibition of RANKL, RANK, TRAF6, p38α, NF-κB, and NFATc1. SCH58261 reversed the effect of EA. These results suggest that EA regulated p38α-MAPK signaling by increasing A2AR activity, which inhibited osteoclastogenesis.

Electroacupuncture Alleviates CFA-Induced Inflammatory Pain via PD-L1/PD-1-SHP-1 Pathway

Inflammatory pain is difficult to treat clinically, but electroacupuncture (EA) has been demonstrated to be effective in alleviating inflammatory pain. Programmed cell death ligand-1 (PD-L1) and its downstream signal, Src homology region two domain-containing phosphatase-1 (SHP-1) have a critical role in relieving inflammatory pain. However, whether the PD-L1/PD-1-SHP-1 pathway mediates the analgesic and anti-inflammatory effects of EA in inflammatory pain remains unclear. Here, we observed that EA reversed the complete Freund's adjuvant (CFA)-induced hyperalgesia. EA reduced the expression of IL-6, iNOS, and NF-κB pathway in dorsal root ganglia (DRG) on day 7 after CFA injection but had no effect on the expression of IL-6, iNOS, and NF-κB PP65 on day 21 after CFA injection. Moreover, EA upregulated the protein levels of the PD-L1/PD-1-SHP-1 pathway on day 7 and day 21 after CFA injection. Furthermore, EA upregulated PD-L1 expression in calcitonin gene-related peptide (CGRP)⁺ but not in isohaemagglutinin B4 (IB4)⁺ and NF200⁺ neurons on day 7 and day 21 after CFA injection. Intrathecal injection of the PD-L1/PD-1 inhibitor BMS-1 (50 or 100 µg) blocked the EA-induced analgesic effect, significantly increased IL-6 and iNOS levels, and reduced the levels of PD-L1/PD-1-SHP-1. BMS-1 (50 or 100 µg) significantly reduced the expression of PD-L1 in IB4⁺, CGRP⁺, and NF200⁺ neurons. Our results show that EA's anti-inflammatory and analgesic effects are associated with activating the PD-L1/PD-1-SHP-1 pathway and suppressing its regulated neuroinflammation. This study provides a new potential therapeutic target for treating inflammatory pain.

Sciatic-Vagal Nerve Stimulation by Electroacupuncture Alleviates Inflammatory Arthritis in Lyme Disease-Susceptible C3H Mice

Lyme disease is caused by Borrelia burgdorferi, and the pathogenesis of the disease is complex with both bacterial and host factors contributing to inflammatory responses. Lyme disease affects different organs including joints and results in arthritis. Immune responses stimulated by B. burgdorferi through toll-like receptors cause infiltration of leukocytes, which produce inflammatory cytokines and facilitate spirochete clearance. However, arthritic manifestations and chronic fatigue syndrome-like symptoms persist long after completion of antibiotic treatment regimens in a significant number of patients. To counter the effects of inflammation, treatment by non-steroidal anti-inflammatory drugs, hydroxychloroquine, or synovectomy to eradicate inflammatory arthritis in the involved joint could be employed; however, they often have long-term consequences. Acupuncture has been used for a long time in Asian medicine to diminish pain during various ailments, but the effects and its mechanism are just beginning to be explored. Control of inflammation by neuronal stimulation has been exploited as a systemic therapeutic intervention to arrest inflammatory processes. Our objective was to determine whether activation of the sciatic-vagal network by electroacupuncture on ST36 acupoint, which is used to control systemic inflammation in experimental models of infectious disorders such as endotoxemia, can also alleviate Lyme arthritis symptoms in mice. This aim was further strengthened by the reports that sciatic-vagal neuronal network stimulation can lead to dopamine production in the adrenal medulla and moderate the production of inflammatory factors. We first assessed whether electroacupuncture affects spirochete colonization to attenuate Lyme arthritis. Interestingly, bioluminescent B. burgdorferi burden detected by live imaging and qPCR were similar in electroacupuncture- and mock-treated mice, while electroacupuncture induced a lasting anti-inflammatory effect on mice. Despite the discontinuation of treatment at 2 weeks, the simultaneous decrease in neutrophils in the joints and inflammatory cytokine levels throughout the body at 4 weeks suggests a systemic and persistent effect of electroacupuncture that attenuates Lyme arthritis. Our results suggest that electroacupuncture-mediated anti-inflammatory responses could offer promising healthcare benefits in patients suffering from long-term Lyme disease manifestations.

Spinal Neuronal GRK2 Contributes to Preventive Effect by Electroacupuncture on Cisplatin-Induced Peripheral Neuropathy in Mice

The main symptoms of chemotherapy-induced peripheral neuropathy (CIPN) include pain and numbness. Neuronal G protein–coupled receptor kinase 2 (GRK2) plays an important role in various pain models. Cisplatin treatment can induce the activation of proinflammatory microglia in spinal cord. The purpose of this study was to investigate the role of spinal neuronal GRK2 in cisplatin-induced CIPN and in the prevention of CIPN by electroacupuncture (EA).

The Adenosine A2B Receptor Drives Osteoclast-Mediated Bone Resorption in Hypoxic Microenvironments

Osteoclast-mediated bone destruction is amplified in the hypoxic synovial microenvironment of rheumatoid arthritis (RA). This increased bone resorption is driven by the hypoxia-inducible transcription factor HIF. We identified hypoxic induction of the HIF-regulated adenosine A_2B receptor in primary human osteoclasts (mRNA, 3.8-fold increase, p < 0.01) and sought to identify the role(s) of purinergic signaling via this receptor in the bone resorption process. Primary human osteoclasts were differentiated from CD14+ monocytes and exposed to hypoxia (2% O₂) and A_2B receptor inhibitors (MRS1754, PSB603). The hypoxic increase in bone resorption was prevented by the inhibition of the A_2B receptor, at least partly by the attenuation of glycolytic and mitochondrial metabolism via inhibition of HIF. A_2B receptor inhibition also reduced osteoclastogenesis in hypoxia by inhibiting early cell fusion (day 3–4, p < 0.05). The A_2B receptor is only functional in hypoxic or inflammatory environments when the extracellular concentrations of adenosine (1.6-fold increase, p < 0.05) are sufficient to activate the receptor. Inhibition of the A_2B receptor under normoxic conditions therefore did not affect any parameter tested. Reciprocal positive regulation of HIF and the A_2B receptor in a hypoxic microenvironment thus enhances glycolytic and mitochondrial metabolism in osteoclasts to drive increased bone resorption. A_2B receptor inhibition could potentially prevent the pathological osteolysis associated with hypoxic diseases such as rheumatoid arthritis.

Adenosine A2A Receptor Mediates Inhibition of Synovitis and Osteoclastogenesis after Electroacupuncture in Rats with Collagen-Induced Arthritis

Background

This study was to investigate the role of adenosine A2A receptors (A2AR) in inhibiting the effect of electroacupuncture (EA) on osteoclastogenesis in collagen-induced arthritis (CIA).

Methods

Wistar rats were divided into four groups: sham-control group, CIA-control group, CIA-EA group, and CIA-EA-SCH58261 (A2AR antagonist) group. We detected tumor necrosis factor-α (TNF-α), nuclear transcription factor-κB (NF-κB), receptor activator of NF-κB ligand (RANKL), protein kinase A (PKA), and extracellular regulatory protein kinase 1/2 (ERK1/2) in peripheral blood by ELISA. PKA, ERK1/2, and NF-κB in ankle joints were determined by western blotting. We evaluated the arthritis damage by histological examination and determined the number of osteoclasts by tartrate-resistant acid phosphatase (TRAP) staining.

Results

EA treatment downregulated the expression of TNF-α, RANKL, PKA, ERK1/2, and NF-κB in peripheral blood but increased the levels of PKA and ERK1/2 in ankle joints. Importantly, EA treatment reduced bone erosion as evidenced by the histological findings and inhibited osteoclastogenesis as revealed by TRAP staining. All these effects of the EA treatment were reversed by combining EA treatment with the A2AR antagonist SCH58261.

Conclusion

Our data suggest that EA treatment activated A2AR. The effects of the A2AR antagonist SCH58261 suggest that the inhibition of osteoclast formation, the inhibition of TNF-α, RANKL, and NF-κB expression, and the increase of ERK1/2 are all dependent on this EA-induced A2AR activation. It is therefore likely that these pathways with clearly defined roles in inflammation and bone erosion are at least partially involved in the mediation of the inhibition of synovitis and osteoclast formation induced by EA.

Electroacupuncture Alleviates Pain Responses and Inflammation in a Rat Model of Acute Gout Arthritis

Acute gout arthritis is one of the most painful inflammatory conditions. Treatments for gout pain are limited to colchicine, nonsteroidal anti-inflammatory drugs, and corticosteroids, which oftentimes result in severe adverse effects. Electroacupuncture (EA) has been proved to be effective in relieving many inflammatory pain conditions with few side effects. Here, we aim to investigate the therapeutic potentials of EA on pain and inflammation of a rat model of acute gout arthritis and underlying mechanisms. We found that 2/100 Hz EA produced the most robust analgesic effect on mechanical hyperalgesia of acute gout arthritis rat model compared with 2 and 100 Hz. EA produced similar analgesic effect compared with indomethacin. 2/100 Hz EA also significantly alleviates the ongoing pain behavior, thermal hyperalgesia, and ankle edema. Locally applied μ and κ-opioid receptor antagonists but not adenosine A₁ receptor antagonist significantly abolished the analgesic effect of EA. Locally applied μ and κ-opioid receptor agonists produced significant antiallodynia on acute gout arthritis rats, mimicking EA. Furthermore, 2/100 Hz EA upregulated β-endorphin expression in inflamed ankle skin tissue. Our results demonstrated, for the first time, that EA can be used for relieving acute gout arthritis with effect dependent on peripheral opioid system and comparable with the one obtained with indomethacin.

Insomnia: can acupuncture help?

Insomnia is the forgotten partner to many medical problems, not least chronic pain where interference with sleep is a common complaint. However, the relationship is complex: lack of sleep can exacerbate pain through increase in proinflammatory cytokine production. Acupuncture is observed clinically to improve sleeping in chronic pain patients, but reviews are unable firmly to recommend acupuncture for insomnia as many trials are methodologically inadequate, despite most being acupuncture positive. However, there is strong evidence for relief in several chronic pain problems and improvement in these is likely also to restore normal sleeping. So, as the safety profile of acupuncture is excellent, it seems reasonable to utilize acupuncture in a nonpharmacological approach to combating insomnia, despite lack of formal evidence.