Electroacupuncture Relieves Pain and Attenuates Inflammation Progression Through Inducing IL-10 Production in CFA-Induced Mice

Astrocyte-Microglia Crosstalk: A Novel Target for the Treatment of Migraine

Migraine is a pervasive neurologic disease closely related to neurogenic inflammation. The astrocytes and microglia in the central nervous system are vital in inducing neurogenic inflammation in migraine. Recently, it has been found that there may be a crosstalk phenomenon between microglia and astrocytes, which plays a crucial part in the pathology and treatment of Alzheimer's disease and other central nervous system diseases closely related to inflammation, thus becoming a novel hotspot in neuroimmune research. However, the role of the crosstalk between microglia and astrocytes in the pathogenesis and treatment of migraine is yet to be discussed. Based on the preliminary literature reports, we have reviewed relevant evidence of the crosstalk between microglia and astrocytes in the pathogenesis of migraine and summarized the crosstalk pathways, thereby hoping to provide novel ideas for future research and treatment.

Interleukin-18 in chronic pain: Focus on pathogenic mechanisms and potential therapeutic targets

Chronic pain has been proven to be an independent disease, other than an accompanying symptom of certain diseases. Interleukin-18 (IL-18), a pro-inflammatory cytokine with pleiotropic biological effects, participates in immune modulation, inflammatory response, tumor growth, as well as the process of chronic pain. Compelling evidence suggests that IL-18 is upregulated in the occurrence of chronic pain. Antagonism or inhibition of IL-18 expression can alleviate the occurrence and development of chronic pain. And IL-18 is located in microglia, while IL-18R is mostly located in astrocytes in the spinal cord. This indicates that the interaction between microglia and astrocytes mediated by the IL-18/IL-18R axis is involved in the occurrence of chronic pain. In this review, we described the role and mechanism of IL-18 in different types of chronic pain. This review provides strong evidence that IL-18 is a potential therapeutic target in pain management.

Acupuncture's long-term impact on depression prevention in primary dysmenorrhea: A 19-year follow-up of a Taiwan cohort with neuroimmune insights

BACKGROUND

Primary dysmenorrhea (PD) is a common gynecological condition causing depression. Acupuncture is an effective option for PD management but its effects on PD-associated depression remain unclear.

METHODS

A retrospective cohort study involving 35,099 propensity score-matched pairs of acupuncture users and non-users with PD was conducted using data from Taiwan's Longitudinal Generation Tracking Database 2000. Cox proportional hazard models were used to estimate depression risk, and bioinformatics analyses were performed to uncover underlying molecular mechanisms.

RESULTS

The risk of developing depression was reduced by 64 % in acupuncture users compared with non-acupuncture users during the 19-year follow-up period. The decrease was dose-dependent. Bioinformatics analyses identified 34 co-expressed targets for acupuncture, PD, and depression; and eight hub genes (coding for interleukin 6 and 1B, tumor necrosis factor, albumin, vascular endothelial growth factor A, C-reactive protein, prostaglandin-endoperoxide synthase 2, and brain-derived neurotrophic factor) potentially involved in the therapeutic effects of acupuncture. Several molecular pathways were found to be involved, including cytokine-cytokine receptor interaction, neuroactive ligand-receptor interaction, cyclic adenosine 3',5'-monophosphate signaling pathway, mitogen-activated protein kinase signaling pathway, serotonergic synapse, and estrogen signaling pathway.

LIMITATIONS

Bias in the selection of participants could have been introduced as a consequence of the retrospective nature of the study. Data were derived from a single national database, and acupuncture treatment details were unavailable.

CONCLUSION

Acupuncture may protect against the development of depression in patients with PD. This study provides insight into the potential molecular mechanisms underlying the therapeutic effects of acupuncture in PD management and depression prevention.

Combined therapy of local recombinant human interferon α1b injection and acupuncture on verruca vulgaris: a retrospective study

Verruca vulgaris is always stubborn to treat. We applied a new combined therapy of local recombinant human interferon alpha 1b (rhIFNα1b) injection plus acupuncture on verruca vulgaris recently to evaluate the efficacy and safety of the combined therapy. The retrospective study was conducted in The First Hospital of China Medical University from 2018 to 2020. Patients with verruca vulgaris were included. Combined therapy with local rhIFNα1b injection plus acupuncture was set as treatment group, rhIFNα1b injection and carbon dioxide (CO2) laser were set as control groups. A total of 2415 patients were included in the study. The cure rates were 81.85%, 85.93%, and 100% in combined group, rhIFNα1b group, and CO2 laser group, separately. All lesions cured in combined group were located on hands or feet, while majority of lesions cured in other groups were located on other sites. For patients with medium/big single lesion or 6-9 lesions, less treatment times were needed in combined group than rhIFNα1b group. For patients with small single, two to five or more than ten lesions, the treatment times of combined group and rhIFNα1b group were comparable. All patients complained of pain in varying degrees when local injection or laser irradiation. Compared with CO2 laser group, more fever, less swelling or scar was reported in combined group. In conclusion, combined therapy of local rhIFNα1b plus acupuncture was beneficial for verruca vulgaris with limited adverse effects. The therapy was more acceptable by younger female patients with verruca vulgaris.

Acupuncture Treatment for Breast Cancer-Related Lymphedema: A Randomized Pilot Study

Background: Methods of conservative management for breast cancer-related lymphedema (BCRL) are burdensome in terms of time, cost, and convenience. In addition, many patients are not candidates for surgical treatment. Preliminary results have demonstrated possible beneficial effects of acupuncture for patients with BCRL. In this small pilot study, we examined the safety and feasibility of an acupuncture randomized control trial (RCT) in this patient cohort, utilizing a battery of standardized clinical and patient-centered outcome measures. Methods and Results: Patients with BCRL were randomized 2:1 to the acupuncture (n = 10) or the control (n = 4) group. Patients received acupuncture to the unaffected extremity biweekly for 6 weeks. Feasibility was defined as enrollment ≥80%, completion of ≥9 of 12 acupuncture sessions per person, and ≥75% completion of three of three measurement visits. To inform a future adequately powered RCT, we describe within-group changes in patient-centered outcomes, including circumferential measurements, bioimpedance spectroscopy, perometry, cytokine levels, and patient quality of life. Adverse events were systematically tracked. Fourteen patients completed the study. Of those who received acupuncture (n = 10), 8 completed all 12 acupuncture sessions, and 2 patients completed 11 sessions. Ninety-three percent of all participants completed all three measurement visits. There was no consistent improvement in arm volumes. Inflammatory marker levels had inconclusive fluctuations among both groups. All patients receiving acupuncture demonstrated an improvement in their functional quality-of-life score. No severe adverse events occurred. Conclusions: A randomized controlled study of acupuncture for BCRL is feasible. The acupuncture intervention is acceptable in this population, without safety concerns in a small sample and warrants further investigation.

Peripheral Activation of Formyl Peptide Receptor 2/ALX by Electroacupuncture Alleviates Inflammatory Pain by Increasing Interleukin-10 Levels and Catalase Activity in Mice

In the context of the electroacupuncture (EA) neurobiological mechanisms, we have previously demonstrated the involvement of formyl peptide receptor 2 (FPR2/ALX) in the antihyperalgesic effect of EA. The present study investigated the involvement of peripheral FPR2/ALX in the antihyperalgesic effect of EA on inflammatory cytokines levels, oxidative stress markers and antioxidant enzymes in an animal model of persistent inflammatory pain. Male Swiss mice underwent intraplantar (i.pl.) injection with complete Freund's adjuvant (CFA). Mechanical hyperalgesia was assessed with von Frey monofilaments. Animals were treated with EA (2/10 Hz, ST36-SP6, 20 minutes) for 4 consecutive days. From the first to the fourth day after CFA injection, animals received i.pl. WRW4 (FPR2/ALX antagonist) or saline before EA. Levels of inflammatory cytokines (TNF, IL-6, IL-4 and IL-10), antioxidant enzymes (catalase and superoxide dismutase), oxidative stress markers (TBARS, protein carbonyl, nitrite/nitrate ratio), and myeloperoxidase activity were measured in paw tissue samples. As previously demonstrated, i.pl. injection of the FPR2/ALX antagonist prevented the antihyperalgesic effect induced by EA. Furthermore, animals treated with EA showed higher levels of IL-10 and catalase activity in the inflamed paw, and these effects were prevented by the antagonist WRW4. EA did not change levels of TNF and IL-6, SOD and MPO activity, and oxidative stress markers. Our work demonstrates that the antihyperalgesic effect of EA on CFA-induced inflammatory pain could be partially associated with higher IL-10 levels and catalase activity, and that these effects may be dependent, at least in part, on the activation of peripheral FPR2/ALX.

Protective Effect of Electroacupuncture on Chemotherapy-Induced Salivary Gland Hypofunction in a Mouse Model

Radiotherapy and chemotherapy can impair salivary gland (SG) function, which causes xerostomia and exacerbate other side effects of chemotherapy and oral infection, reducing patients' quality of life. This animal study aimed to assess the efficacy of electroacupuncture (EA) as a means of preventing xerostomia induced by 5-fluorouracil (5-FU). A xerostomia mouse model was induced via four tail vein injections of 5-FU (80 mg/kg/dose). EA was performed at LI4 and LI11 for 7 days. The pilocarpine-stimulated salivary flow rate (SFR) and salivary glands weight (SGW) were recorded. Salivary immunoglobulin A (SIgA) and lysozyme were determined via enzyme-linked immunosorbent assay (ELISA). SG was collected for hematoxylin and eosin staining to measure acini number and acinar cell size. Tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and aquaporin 5 (AQP5) mRNA expressions in SG were quantified via RT-qPCR. 5-FU caused significant decreases in SFR, SGW, SIgA, lysozyme, AQP5 expression, and acini number, while TNF-α and IL-1β expressions and acinar cell size were significantly increased. EA treatment can prevent 5-FU damage to the salivary gland, while pilocarpine treatment can only elevate SFR and AQP5 expression. These findings provide significant evidence to support the use of EA as an alternative treatment for chemotherapy-induced salivary gland hypofunction and xerostomia.

Electroacupuncture improves gout arthritis pain via attenuating ROS-mediated NLRP3 inflammasome overactivation

BACKGROUND

Gout results from disturbed uric acid metabolism, which causes urate crystal deposition in joints and surrounding tissues. Gout pain management is largely limited to colchicine and nonsteroidal anti-inflammatory drugs. Constant usage of these medications leads to severe side effects. We previously showed electroacupuncture (EA) is effective for relieving pain in animal model of gout arthritis. Here we continued to study the mechanisms underlying how EA alleviates gout pain.

METHODS

Monosodium urate was injected into ankle joint to establish gout arthritis model in mice. EA or sham EA was applied at ST36 and BL60 acupoints of model animals. Biochemical assays, immunostaining, live cell Ca²⁺ imaging and behavioral assays were applied.

RESULTS

Model mice displayed obvious mechanical allodynia, accompanied with gait impairments. EA attenuated mechanical hypersensitivities and improved gait impairments. EA reduced the overexpression of NLRP3 inflammasome signaling molecules in ankle joints of model animals. EA-induced anti-allodynia, as well as inhibition on NLRP3 inflammasome, were mimicked by antagonizing but abolished by activating NLRP3 inflammasome via pharmacological methods. EA attenuated oxidative stress, an upstream signaling of NLRP3 inflammasome in ankle joints of model mice. Exogenously increasing oxidative stress abolished EA's inhibitory effect on NLRP3 inflammasome and further reversed EA's anti-allodynic effect. EA reduced neutrophil infiltrations in ankle joint synovium, a major mechanism contributing to oxidative stress in gout. Pharmacological blocking NLRP3 inflammasome or EA reduced TRPV1 channel overexpression in dorsal root ganglion (DRG) neurons. Ca²⁺ imaging confirmed that EA could reduce functional enhancement in TRPV1 channel in DRG neurons during gout.

CONCLUSIONS

Our results demonstrate that EA reduces gout pain possibly through suppressing ROS-mediated NLRP3 inflammasome activation in inflamed ankle joints and TRPV1 upregulation in sensory neurons, supporting EA as a treatment option for gout pain.

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.

The involvement of the primo vascular system in local enteritis and its modification by electroacupuncture

Introduction

The primo vascular system (PVS), an intensive network structure, has been claimed to be representative of the acupuncture meridian. Here, we explored the role of the PVS in local enteritis and its modification by acupuncture.

Methods

Chronic cecitis in rabbits was induced by 2,4,6-trinitro-benzene-sulfonic acid (TNBS). The PVS on the cecum was visualized with trypan blue staining, and collected with the help of microsurgical forceps under an optical stereomicroscope.

Results

The increased primo vessels (PVs) and primo nodes (PNs) of the PVS on the surface of the cecum were induced by local inflammation, which was positively correlated with the inflammatory cells in the cecal mucosa. Tandem mass tag (TMT) based proteomic analysis revealed that 110 differentiated proteins of the PVS existed between TNBS-treated and control rabbits; 65 proteins were upregulated, while 45 proteins were downregulated. These proteins were mainly enriched in inflammation- and immunity-related processes, such as inflammatory cell proliferation, antigen presentation, and cell adhesion in the proliferated PVS (data are available via ProteomeXchange with the identifiers PXD034280). Importantly, TNBS-induced cecitis, the proliferated PVS and inflammation response-related proteins (CD40, CD45, HLA-DRA1, LAMP1, JAGN1 and FGL1) in the PVS were alleviated or reversed by repetitive electroacupuncture (EA) stimulations.

Conclusion

These results suggest that the proliferated PVS and its active inclusions were related to the inflammatory process, which was modified by EA. Our study provides a new avenue for further exploration of the mechanism by which EA exerts anti-inflammatory effects.

Changes of local microenvironment and systemic immunity after acupuncture stimulation during inflammation: A literature review of animal studies

An increasing number of studies have demonstrated the underlying mechanisms by which acupuncture therapy mediates both local and systemic immunomodulation. However, the connection between alterations in the local microenvironment and the resulting change in systemic immunity remains unclear. In this review, we focus on cell-specific changes in local immune responses following acupuncture stimulation and their link to systemic immune modulation. We have gathered the most recent evidence for chemo- and mechano-reactive changes in endothelial cells, neutrophils, macrophages, and mast cells in response to acupuncture. Local signaling is then related to the activation of systemic neuro-immunity including the cholinergic, adrenal, and splenic nervous systems and pain-related neuromodulation. This review aims to serve as a reference for further research in this field.

Research Hotspots and Trends on Acupuncture for Anti-Inflammation: A Bibliometric Analysis from 2011 to 2021

Purpose

We here explored the research status, research hotspots, and development trend of acupuncture against inflammation from both quantitative and qualitative aspects through bibliometrics.

Methods

We used CiteSpace and VOSviewer to analyze the literature about acupuncture against inflammation from 2011 to 2021 in the Web of Science Core Collection database by using a visual knowledge map.

Results

In total, 1479 articles were included, and the number of articles published each year exhibited an upward trend. The largest number of articles were published in China (661), followed by the United States (287) and South Korea (164). The most productive institution is Beijing University of Chinese Medicine (72), while the most influential institution is the Capital Medical University (0.28). Evidence-based Complementary and Alternative Medicine (131) is the journal that published most articles on the topic. Lin Yiwen is the most prolific author, and Borovikova L is the most influential co-cited author. The keywords that have burst in the last 2 years are inflammation and activation. The keywords with the highest frequency of use are electroacupuncture (EA), inflammation, and expression.

Conclusion

The number of publications on acupuncture for anti-inflammation research is rapidly increasing. China is a productive country, but the influence of centrality is poor. Research institutions are concentrated in universities, and the whole collaborative network needs to be strengthened. The anti-inflammatory mechanism of acupuncture is the main focus of research in this field. Regulation of immune cell balance by acupuncture may be a hot topic in mechanism research. At present, immune cells, vagus nerve, signal pathway, inflammatory corpuscles, cytokines and neurotransmitters are popular research topics. In the future, the basic research of acupuncture for anti-inflammation transformed into clinical practice may be a trend. EA and bee venom acupuncture may be promising research directions for acupuncture treatment for inflammatory diseases.

Mechanisms of acupuncture-electroacupuncture on inflammatory pain

Acupuncture, as a traditional treatment, has been extensively used in China for thousands of years. According to the World Health Organization (WHO), acupuncture is recommended for the treatment of 77 diseases. And 16 of these diseases are related to inflammatory pain. As a combination of traditional acupuncture and modern electrotherapy, electroacupuncture (EA) has satisfactory analgesic effects on various acute and chronic pain. Because of its good analgesic effects and no side effects, acupuncture has been widely accepted all over the world. Despite the increase in the number of studies, the mechanisms via which acupuncture exerts its analgesic effects have not been conclusively established. A literature review of related research is of great significance to elaborate on its mechanisms and to inform on further research directions. We elucidated on its mechanisms of action on inflammatory pain from two levels: peripheral and central. It includes the mechanisms of acupuncture in the periphery (immune cells and neurons, purinergic pathway, nociceptive ion channel, cannabinoid receptor and endogenous opioid peptide system) and central nervous system (TPRV1, glutamate and its receptors, glial cells, GABAergic interneurons and signaling molecules). In this review, we collected relevant recent studies to systematically explain the mechanisms of acupuncture in treating inflammatory pain, with a view to providing direction for future applications of acupuncture in inflammatory pain and promoting clinical development.

Electroacupuncture alleviates traumatic brain injury by inhibiting autophagy via increasing IL-10 production and blocking the AMPK/mTOR signaling pathway in rats

Autophagy, switched by the AMPK/mTOR signaling, has been revealed to contribute greatly to traumatic brain injury (TBI). Electroacupuncture (EA) is a promising therapeutic method for TBI, however, the underlying mechanism is still unclear. Herein, we hypothesize that the therapeutic effect of EA on TBI is associated with its inhibition on AMPK/mTOR-mediated autophagy. Sprague-Dawley rats were randomly divided into three groups: sham, TBI, and TBI + EA. TBI model was established by using an electronic controlled cortical impactor. Rats were treated with EA at 12 h after modeling, 15 min daily for 14 consecutive days. EA was applied at the acupuncture points Quchi (LI 11), Hegu (LI4), Baihui (GV20), Guanyuan (CV4), Zusanli (ST36) and Yongquan (KI1), using dense-sparse wave, at frequencies of 1 Hz, and an amplitude of 1 mA. After 3, 7 and 14 days of modeling, the modified neurological severity scale (mNSS), rota rod system, and Morris Water Maze (MWM) test showed that EA treatment promoted neurological function recovery in TBI rats. Moreover, EA treatment alleviated brain edema, pathological damage, neuronal apoptosis in TBI rats. EA improved abnormal ultrastructure, including abnormal mitochondrial morphology and increased autophagosomes, in the brain neurons of TBI rats, as measured by transmission electron microscopy, and the concentration of adenosine triphosphate (ATP), adenosine diphosphate (ADP), and adenosine monophosphate (AMP). Western blot and immunohistochemistry (IHC) assays were performed to measure the protein levels of interleukin 10 (IL-10), autophagy-related proteins and key proteins in the AMPK/mTOR signaling pathway. EA treatment increased IL-10 production, inhibited the AMPK/mTOR signaling, and inhibited excessive autophagy in TBI rats. Additionally, AMPK inhibitor Compound C treatment had similar effects to EA. Both AMPK agonist AICAR and IL-10 neutralizing antibody treatments reversed the effects of EA on the related protein levels of autophagy and the AMPK/mTOR signaling pathway, and abolished the protective effects of EA on TBI rats. In conclusion, EA treatment promoted neurological function recovery and alleviated pathological damage and neuronal apoptosis in TBI rats through inhibiting excessive autophagy via increasing IL-10 production and blocking the AMPK/mTOR signaling pathway.

Glucocorticoid Receptor Contributes to Electroacupuncture-Induced Analgesia by Inhibiting Nav1.7 Expression in Rats With Inflammatory Pain Induced by Complete Freund's Adjuvant

BACKGROUND

While electroacupuncture (EA) has been used traditionally for the treatment of chronic pain, its analgesic mechanisms have not been fully clarified. We observed in an earlier study that EA could reverse inflammatory pain and suppress high Nav1.7 expression. However, the molecular mechanism underlying Nav1.7 expression regulation is unclear. In this study, we studied the relationship between the glucocorticoid receptor (GR) and Nav1.7 and the role of these molecules in EA analgesia.

MATERIALS AND METHODS

In this study, we established an inflammatory pain model by intraplantar injection of complete Freund's adjuvant (CFA) in rats. EA stimulation was applied to the ipsilateral "Huantiao" (GB30) and "Zusanli" (ST36) acupoints in the rat model. Western blotting, real-time polymerase chain reaction, immunostaining, intrathecal injection, and chromatin immunoprecipitation (ChIP) assay were performed to determine whether the sodium channel protein Nav1.7 plays a role in CFA-induced pain and whether GR regulates Nav1.7 expression during analgesia following EA stimulation.

RESULTS

EA application significantly decreased the paw withdrawal threshold thresholds and thermal paw withdrawal latency and suppressed GR and Nav1.7 expression in the dorsal root ganglion. Moreover, treatment with a GR sense oligonucleotide (OND) markedly reversed these alterations. In contrast, treatment with a GR antisense OND along with EA application exerted a better analgesic effect, which was accompanied by the suppression of Nav1.7 and GR protein expression. The ChIP assay showed that the binding activity of GR to the Nav1.7 promoter was enhanced in CFA injected rats and suppressed in EA-treated rats.

CONCLUSIONS

The present study demonstrated that EA exerted anti-hyperalgesic effects by inhibiting GR expression, which led to Nav1.7 expression modulation in the rat model of CFA-induced inflammatory pain.

The NLR family pyrin domain containing 3 inflammasome in the mechanism of electroacupuncture: Current status and future perspectives

Electroacupuncture, which is the most widely used alternative medicine treatment, has been gradually recognized for its effectiveness; however, its mechanism of action is not fully understood. The NLR family pyrin domain containing 3 (NLRP3) inflammasome is a thoroughly studied inflammasome that is closely associated with Alzheimer’s disease, spinal cord injury, and other diseases and plays an important role in the diagnosis and treatment of human immune system diseases. In recent years, some scholars have found that the NLRP3 inflammasome is a part of the mechanism of action of electroacupuncture, which has attracted further attention. In the current review, using “electroacupuncture” and “NLRP3 inflammasome” as keywords and based on the existing randomized controlled trials or clinical trials, we summarize the mechanisms of electroacupuncture targeting NLRP3 inflammasome in the treatment of different diseases and discuss how to optimize the electroacupuncture protocol to obtain thorough mechanisms of NLRP3 inflammasome in electroacupuncture and improve the level of evidence.

Electroacupuncture Ameliorates Mechanical Allodynia of a Rat Model of CRPS-I via Suppressing NLRP3 Inflammasome Activation in Spinal Cord Dorsal Horn Neurons

Complex regional pain syndrome type-I (CRPS-I) is a chronic neurological disorder that results in severe pain and affects patients' life quality. Conventional therapies usually lack effectiveness. Electroacupuncture (EA) is an effective physical therapy for relieving CRPS-I pain. However, the mechanism underlying EA-induced analgesia on CRPS-I still remain unknown. Spinal NLRP3 inflammasome was recently identified to contribute to pain and neuroinflammation in a rat model of CRPS-I by our group. Here, we aimed to study whether EA could inhibit spinal NLRP3 inflammasome activation, thus resulting in pain relief and attenuation of spinal neuroinflammation in the rat model of CRPS-I. We established the rat chronic post-ischemic pain (CPIP) model to mimic CRPS-I. CPIP rats developed remarkable mechanical allodynia that could be relieved by daily EA intervention. NLRP3 inflammasome was activated in spinal cord dorsal horn (SCDH) of CPIP rats, accompanied with over-production of pro-inflammatory cytokine IL-1β. Immunostaining revealed that the cellular distribution of NLRP3 was predominantly located in SCDH neurons. Pharmacological activation of NLRP3 inflammasome per se is sufficient to produce persistent mechanical allodynia in naïve animals, whereas blocking NLRP3 inflammasome attenuates mechanical allodynia of CPIP rats. EA exclusively reduced NLRP3 overexpression in SCDH neurons and attenuated spinal glial cell over-activation in CPIP rats. EA-induced anti-allodynia with attenuation of spinal glial cell over-activation were all mimicked by intrathecal blocking NLRP3 inflammasome and reversed by activating NLRP3 inflammasome, respectively, through pharmacological methods. Finally, spinal blocking IL-1β attenuated mechanical allodynia and spinal glial cell over-activation in CPIP rats, resembling the effects of EA. In all, these results demonstrate that spinal NLRP3 inflammasome activation contributes to mechanical allodynia of the rat model of CRPS-I and EA ameliorates mechanical allodynia through inhibiting NLRP3 inflammasome activation in SCDH neurons. Our study further supports EA can be used as an effective treatment for CRPS-I.

Role of cathepsin K in the expression of mechanical hypersensitivity following intra-plantar inflammation

Persistent/chronic inflammatory pain involves multiple pathophysiological mechanisms and is far more complex than acute/momentary pain. Current therapeutics for chronic inflammatory pain are often not effective because the etiology responsible for the pain is not addressed by traditional pharmacological treatments. Cathepsin K is a cysteine protease that has mostly been studied in the context of bone and joint disorders. Previous work by others has shown that inhibition of cathepsin K activity reduces osteoarthritis-associated nociception in joints. However, the role of cathepsin K in cutaneous inflammation is understudied. We assessed the effectiveness of genetic deletion or pharmacological inhibition of cathepsin K in male mice on the expression of nocifensive behaviors after formalin injection or mechanical and thermal hypersensitivity after injection of complete Freund’s adjuvant (CFA) into the mouse hind paw. Our data demonstrate that cathepsin K knockout mice (Ctsk^−/−) have a reduction in nocifensive behaviors in the formalin test. In addition, Ctsk^−/− do not develop mechanical hypersensitivity after CFA injection for up to 7 days. Moreover, we found that inhibition of cathepsin K reduced mechanical hypersensitivity after CFA injection and mRNA levels, protein levels, and cathepsin K activity levels were elevated after CFA injection. Based upon our data, cathepsin K is indicated to play a role in the expression of chemically-induced cutaneous hypersensitivity, as Ctsk^−/− mice do not develop mechanical hypersensitivity and show a reduction in nocifensive behaviors. Further research is needed to determine whether attenuating cathepsin K activity may generate a clinically relevant therapeutic.

The Anti-Inflammatory Actions and Mechanisms of Acupuncture from Acupoint to Target Organs via Neuro-Immune Regulation

Inflammation plays a significant role in the occurrence and development of multiple diseases. This study comprehensively reviews and presents literature from the last five years, showing that acupuncture indeed exerts strong anti-inflammatory effects in multiple biological systems, namely, the immune, digestive, respiratory, nervous, locomotory, circulatory, endocrine, and genitourinary systems. It is well known that localized acupuncture-mediated anti-inflammatory effects involve the regulation of multiple populations and functions of immune cells, including macrophages, granulocytes, mast cells, and T cells. In acupuncture stimulation, macrophages transform from the M1 to the M2 phenotype and the negative TLR4 regulator PPARγ is activated to inhibit the intracellular TLR/MyD88 and NOD signaling pathways. The downstream IκBα/NF-κB and P38 MAPK pathways are subsequently inhibited by acupuncture, followed by suppressed production of inflammasome and proinflammatory mediators. Acupuncture also modulates the balance of helper T cell populations. Furthermore, it inhibits oxidative stress by enhancing SOD activity via the Nrf2/HO-1 pathway and eliminates the generation of oxygen free radicals, thereby preventing inflammatory cell infiltration. The anti-inflammatory effects of acupuncture on different biological systems are also specific to individual organ microenvironments. As part of its anti-inflammatory action, acupuncture deforms connective tissue and upregulates the secretion of various molecules in acupoints, further activating the NF-κB, MAPK, and ERK pathways in mast cells, fibroblasts, keratinocytes, and monocytes/macrophages. The somatic afferents present in acupuncture-activated acupoints also convey sensory signals to the spinal cord, brainstem, and hypothalamic neurons. Upon information integration in the brain, acupuncture further stimulates multiple neuro-immune pathways, including the cholinergic anti-inflammatory, vagus-adrenal medulla-dopamine, and sympathetic pathways, as well as the hypothalamus-pituitary-adrenal axis, ultimately acting immune cells via the release of crucial neurotransmitters and hormones. This review provides a scientific and reliable basis and viewpoints for the clinical application of acupuncture in various inflammatory conditions.

Moxibustion Inhibits the Expression of Colonic NLRP3 through miR7/RNF183/NF-κB Signaling Pathway in UC Rats

Background

Moxibustion has been recognized as an effective approach for ulcerative colitis, yet its mechanism is not clear. The research aimed to investigate the influence of moxibustion on the activation of NLRP3 inflammasome and its mechanism in treating ulcerative colitis by observing miR7/RNF183 inducing IκB α ubiquitination to regulate NF-κB signaling pathway in an ulcerative colitis rat model.

Methods

An ulcerative colitis rat model was established by unlimited access to self-administration of 3.5% (w/v) dextran sulfate sodium solution. Mild moxibustion was applied to bilateral Tianshu points (ST25) in the moxa-stick moxibustion group; rats in the control group were intervened by intraperitoneal injection of ubiquitination inhibitor, MG132. The disease activity index was determined at the end of the intervention; colon injury was observed and scored after hematoxylin-eosin staining; the immunohistochemical method was adopted to detect the expressions of colonic IL-1β and NLRP3 proteins; Western blot determined the expressions of RNF183, IκB α, and NF-κB p65 proteins in the colon; the immunofluorescence test was used to observe the coexpression of IκB α/ubiquitin and IκB α/RNF183 proteins in the colon; immunoprecipitation assay was adopted to observe the interaction between IκB α and RNF183 proteins; and quantitative real-time polymerase chain reaction determined the expression of colonic miR7.

Results

Moxibustion lowered the disease activity index, manifesting as restored colonic tissue and reduced inflammatory reaction, and decreased expression levels of NLRP3 and IL-1β proteins, compared with the model group. It also reduced colonic expression of NF-κB p65 protein, together with the increased level of IκB α protein and weaker expression levels of ubiquitin and RNF183 proteins and mRNAs and stronger expression of miR7. There were no significant differences between the moxa-stick moxibustion group and the control group except the expressions of RNF183 protein and mRNA and miR7.

Conclusion

Moxibustion encourages the recovery of colon injury probably by regulating the expression of NLRP3 protein in ulcerative colitis rats through miR7/RNF183/NF-κB signaling pathway.

Genome-Wide Regulation of Acupuncture and Moxibustion on Ulcerative Colitis Rats

Acupuncture and moxibustion have definite clinical effects on treating ulcerative colitis (UC), but their mechanism is still unclear. To investigate the molecular mechanisms, we applied herb-partitioned moxibustion or electroacupuncture at the Tianshu (ST25) points on UC rats and used RNA sequencing to identify molecular consequences. Male Sprague Dawley (SD) rats were divided into 6 groups randomly: the normal control (NC) group, the control + herb-partitioned moxibustion (NCHM) group, the control + electroacupuncture (NCEA) group, the model (UC) group, the model + herb-partitioned moxibustion (UCHM) group, and the model + electroacupuncture (UCEA) group. Compared to the UC group, HE staining in the UCHM group and UCEA group indicated that colitis was relieved, the histopathological score and MPO were both significantly reduced, and the serum hs-CRP concentration was decreased significantly. The results of RNA-seq suggested that, compared to the NC group, 206 upregulated genes and 167 downregulated genes were identified in colon tissues from the UC group; compared to the UC group, the expression levels of some genes were both affected in the UCHM group and the UCEA group (684 differentially expressed genes were identified in the UCHM group, and 1182 differentially expressed genes were identified in the UCEA group). KEGG signal pathway analysis indicated that the differentially expressed genes in the UCHM group were associated with the JAK-STAT signaling pathway and cell adhesion molecule (CAM); the differentially expressed genes in the UCEA group were associated with the NF-κB signaling pathway, the toll-like receptor signaling pathways, the PI3K-Akt signaling pathway, the MAPK signaling pathway, and the Wnt signaling pathway. This is the first study to reveal the gene expression characteristics of the anti-inflammatory effect of UC rats from the perspective of acupuncture and moxibustion control, which provide a clue for further investigation into the molecular mechanisms of UC treatment by acupuncture and moxibustion.

Effects of Electroacupuncture on Alleviating Prostatodynia and Inflammation in Rats with Chronic Nonbacterial Prostatitis

Purpose

Chronic prostatitis (CP) is a common urinary disease characterized by a complex sequence of symptoms including prostatodynia, which results in significant physical pain and mental burden to affected patients. Currently, CP has no standard treatment. Thus, physical therapy electroacupuncture (EA) which has been successful in treating several inflammation-related pain conditions was used to determine its effect on rats with CP.

Materials and Methods

Rats were castrated and treated with beta-estradiol for 28 days for CP modeling, and EA was initiated one week after. Following three weeks of treatment, pain-related behavioral testing, mechanical withdrawal threshold, and potential histopathological mechanisms were examined.

Results

EA treatment produced a significant antinociceptive effect, effectively increasing the pain threshold of CP rats, and the biochemical results revealed significantly lowered prostatic specific antigen levels. Histopathological results also demonstrated that EA exerted protective properties on prostate morphological changes, as well as decreased inflammation cytokines and oxidative stress molecular expressions in prostate tissue. Furthermore, EA alleviated microglial and astrocyte activation in the dorsal horn of the spinal cord, decreasing CXC motif ligand 1 expressions in activated spinal astrocytes.

Conclusion

In conclusion, it was demonstrated that EA alleviated CP-induced pain, which was partly achieved by the downregulation of inflammation, oxidative stress, and spinal cord glial activation.

Role of Neuroimmune Crosstalk in Mediating the Anti-inflammatory and Analgesic Effects of Acupuncture on Inflammatory Pain

Inflammatory pain is caused by peripheral tissue injury and inflammation. Inflammation leads to peripheral sensitization, which may further cause central sensitization, resulting in chronic pain and progressive functional disability. Neuroimmune crosstalk plays an essential role in the development and maintenance of inflammatory pain. Studies in recent years have shown that acupuncture can exert anti-inflammatory and analgesic effects by regulating peripheral (i.e., involving local acupoints and inflamed regions) and central neuroimmune interactions. At the local acupoints, acupuncture can activate the TRPV1 and TRPV2 channels of mast cells, thereby promoting degranulation and the release of histamine, adenosine, and other immune mediators, which interact with receptors on nerve endings and initiate neuroimmune regulation. At sites of inflammation, acupuncture enables the recruitment of immune cells, causing the release of opioid peptides, while also exerting direct analgesic effects via nerve endings. Furthermore, acupuncture promotes the balance of immune cells and regulates the release of inflammatory factors, thereby reducing the stimulation of nociceptive receptors in peripheral organs. Acupuncture also alleviates peripheral neurogenic inflammation by inhibiting the release of substance P (SP) and calcitonin gene-related peptide from the dorsal root ganglia. At the central nervous system level, acupuncture inhibits the crosstalk between glial cells and neurons by inhibiting the p38 MAPK, ERK, and JNK signaling pathways and regulating the release of inflammatory mediators. It also reduces the excitability of the pain pathway by reducing the release of excitatory neurotransmitters and promoting the release of inhibitory neurotransmitters from neurons and glial cells. In conclusion, the regulation of neuroimmune crosstalk at the peripheral and central levels mediates the anti-inflammatory and analgesic effects of acupuncture on inflammatory pain in an integrated manner. These findings provide novel insights enabling the clinical application of acupuncture in the treatment of inflammatory diseases.

Electroacupuncture-Induced Muscular Inflammatory Pain Relief Was Associated With Activation of Low-Threshold Mechanoreceptor Neurons and Inhibition of Wide Dynamic Range Neurons in Spinal Dorsal Horn

Acupuncture is an effective alternative therapy for pain management. Evidence suggests that acupuncture relieves pain by exciting somatic afferent nerve fibers. However, the mechanism underlying the interaction between neurons in different layers of the spinal dorsal horn induced by electroacupuncture (EA) remains unclear. The aim of this study was to explore the mechanism of EA relieving inflammatory muscle pain, which was associated with activation of the spontaneous firing of low-threshold mechanoreceptor (LTM) neurons and inhibition of wide dynamic range (WDR) neuronal activities in the spinal dorsal horn of rats. Inflammatory muscle pain was induced by injecting complete Freund’s adjuvant into the right biceps femoris muscle. EA with intensity of threshold of A fibers (Ta) in Liangqiu (ST34) muscle considerably inhibited the abnormal spontaneous activities of electromyography (EMG) due to muscle inflammation. While EA with intensity of C-fiber threshold (Tc) increased the abnormal activities of EMG. EA with Ta also ameliorated the imbalance of weight-bearing behavior. A microelectrode array with 750-μm depth covering 32 channels was used to record the neuronal activities of WDR and LTM in different layers of the spinal dorsal horn. The spontaneous firing of LTM neurons was enhanced by EA-Ta, while the spontaneous firing of WDR neurons was inhibited. Moreover, EA-Ta led to a significant inverse correlation between changes in the frequency of WDR and LTM neurons (r = −0.64, p < 0.05). In conclusion, the results indicated that EA could alleviate inflammatory muscle pain, which was associated with facilitation of the spontaneous firing of LTM neurons and inhibition of WDR neuronal activities. This provides a promising evidence that EA-Ta could be applied to relieve muscular inflammatory pain in clinical practice.

Acupuncture for Paclitaxel-Induced Peripheral Neuropathy: A Review of Clinical and Basic Studies

Paclitaxel-induced peripheral neuropathy (PIPN) is a common and intractable side effect of the conventional chemotherapeutic agent paclitaxel. Acupuncture has been reported as an effective alternative therapy in treatment of PIPN in both basic studies and clinical trials. However, there is a lack of comprehensive surveys to summarize the action of acupuncture in management of PIPN. In this review, we briefly demonstrate the basic pathology of PIPN, which includes the activation of ion channels, mitochondrial dysfunction, disruption of axonal transport and also neuro-inflammatory involvement. Meanwhile, we review both the clinical and basic studies as an emphasis to give a general overview of the therapeutic effect of acupuncture against PIPN. Finally, we summarize the current known mechanisms underlying the action of acupuncture against PIPN mainly at peripheral and spinal levels, which include various neurotransmitters, multiple receptors, different types of enzymes and molecules. In conclusion, acupuncture could be considered as a potential alternative therapy in treatment of PIPN, and further clinical and experimental studies are called for in the future.

The NLRP3 inflammasome: an emerging therapeutic target for chronic pain

Chronic pain affects the life quality of the suffering patients and posts heavy problems to the health care system. Conventional medications are usually insufficient for chronic pain management and oftentimes results in many adverse effects. The NLRP3 inflammasome controls the processing of proinflammatory cytokine interleukin 1β (IL-1β) and is implicated in a variety of disease conditions. Recently, growing number of evidence suggests that NLRP3 inflammasome is dysregulated under chronic pain condition and contributes to pathogenesis of chronic pain. This review provides an up-to-date summary of the recent findings of the involvement of NLRP3 inflammasome in chronic pain and discussed the expression and regulation of NLRP3 inflammasome-related signaling components in chronic pain conditions. This review also summarized the successful therapeutic approaches that target against NLRP3 inflammasome for chronic pain treatment.

Hypoglycemic Effect of Electroacupuncture Combined with Antrodia cinnamomea in Dexamethasone-Induced Insulin-Resistant Rats

Objective: Antrodia cinnamomea (AC), a medicinal mushroom indigenous to Taiwan, exerts various pharmacologic activities. This study compared and evaluated the hypoglycemic effect of treatment with electroacupuncture (EA) combined with AC in steroid-induced insulin-resistant (SIIR) rats. Materials and Methods: Rats were divided into saline, EA, AC, AC+EA, and rosiglitazone (TZD) groups. Plasma-glucose levels were measured in serial blood samples and compared before and after treatment in each group. The levels of signaling proteins-glucose transporter 4, (GLUT4), phosphoinositide 3-kinase (PI3-K), and 5' adenosine monophosphate-activated protein kinase (AMPK)-were analyzed by Western blotting to explore their mechanisms of action. Results: The AC+EA group had reduced plasma-glucose levels at 30 and 60 minutes in SIIR rats, compared to normal rats, and this was better than the EA, AC, and TZD groups at 60 minutes. Furthermore, the signaling protein (GLUT4, PI3-K, and AMPK) levels were increased significantly. Conclusions: These findings showed improved hypoglycemic activity and insulin resistance after EA combined with AC treatment. Therefore, the combined therapy might be a more-effective method than the individual therapies that elevates the expression of the signal proteins, as observed in this study.

The Role of Neuroglial Crosstalk and Synaptic Plasticity-Mediated Central Sensitization in Acupuncture Analgesia

Although pain is regarded as a global public health priority, analgesic therapy remains a significant challenge. Pain is a hypersensitivity state caused by peripheral and central sensitization, with the latter considered the culprit for chronic pain. This study summarizes the pathogenesis of central sensitization from the perspective of neuroglial crosstalk and synaptic plasticity and underlines the related analgesic mechanisms of acupuncture. Central sensitization is modulated by the neurotransmitters and neuropeptides involved in the ascending excitatory pathway and the descending pain modulatory system. Acupuncture analgesia is associated with downregulating glutamate in the ascending excitatory pathway and upregulating opioids, 𝛾-aminobutyric acid, norepinephrine, and 5-hydroxytryptamine in the descending pain modulatory system. Furthermore, it is increasingly appreciated that neurotransmitters, cytokines, and chemokines are implicated in neuroglial crosstalk and associated plasticity, thus contributing to central sensitization. Acupuncture produces its analgesic action by inhibiting cytokines, such as interleukin-1β, interleukin-6, and tumor necrosis factor-α, and upregulating interleukin-10, as well as modulating chemokines and their receptors such as CX3CL1/CX3CR1, CXCL12/CXCR4, CCL2/CCR2, and CXCL1/CXCR2. These factors are regulated by acupuncture through the activation of multiple signaling pathways, including mitogen-activated protein kinase signaling (e.g., the p38, extracellular signal-regulated kinases, and c-Jun-N-terminal kinase pathways), which contribute to the activation of nociceptive neurons. However, the responses of chemokines to acupuncture vary among the types of pain models, acupuncture methods, and stimulation parameters. Thus, the exact mechanisms require future clarification. Taken together, inhibition of central sensitization modulated by neuroglial plasticity is central in acupuncture analgesia, providing a novel insight for the clinical application of acupuncture analgesia.

Tetrahydropalmatine exerts analgesic effects by promoting apoptosis and inhibiting the activation of glial cells in rats with inflammatory pain

BACKGROUND

Pain is an unpleasant sensory experience that usually plays a protective role. Inflammatory pain is often severe and stubborn, which has a great impact on the quality of life of patients. However, there has been no breakthrough in the treatment strategy and mechanism of inflammatory pain.

METHODS

This study investigated the analgesic effect of tetrahydropalmatine (THP) in rats injected with complete Freund's adjuvant (CFA)-induced inflammatory pain. Allodynia and gait analysis of rats were used to evaluate the analgesic effect at different time points before and after operation. THP (2.5, 5, and 10 mg/kg) was administered intraperitoneally once daily for 7 days post Day 3. The expression levels of TNF-α and IL-1β in the spinal cord were measured by enzyme-linked immunosorbent assay. The activation of astrocytes and microglial cells in the spinal cord was tested by western blot before and after THP treatment. The apoptosis of glial cells was tested by flow cytometry after treatment with THP in the primary cultured glial cell model.

RESULTS

CFA treatment induced significant allodynia and caused abnormal gait in rats. Administration of THP at 10 mg/kg significantly alleviated CFA-induced inflammatory pain behaviors. Moreover, CFA-induced activation of glial cells and the increased levels of TNF-α and IL-1β were inhibited by THP administration. In addition, THP promotes apoptosis in primary cultured glial cells. This study suggests the possible clinical utility of THP in the treatment of inflammatory pain.

CONCLUSION

THP plays an analgesic role by inhibiting the activation of glial cells and promoting apoptosis.