Correlation between gene expression and MRI STIR signals in patients with chronic low back pain and Modic changes indicates immune involvement.

Disability and distress caused by chronic low back pain (LBP) lacking clear pathoanatomical explanations cause huge problems both for patients and society. A subgroup of patients has Modic changes (MC), identifiable by MRI as vertebral bone marrow lesions. The cause of such changes and their relationship to pain are not yet understood. We explored the pathobiology of these lesions using profiling of gene expression in blood, coupled with an edema-sensitive MRI technique known as short tau inversion recovery (STIR) imaging. STIR images and total RNA from blood were collected from 96 patients with chronic LBP and MC type I, the most inflammatory MC state. We found the expression of 37 genes significantly associated with STIR signal volume, ten genes with edema abundancy (a constructed combination of STIR signal volume, height, and intensity), and one gene with expression levels significantly associated with maximum STIR signal intensity. Gene sets related to interferon signaling, mitochondrial metabolism and defense response to virus were identified as significantly enriched among the upregulated genes in all three analyses. Our results point to inflammation and immunological defense as important players in MC biology in patients with chronic LBP.

Spinal CCK contributes to somatic hyperalgesia induced by orofacial inflammation combined with stress in adult female rats.

In some chronic primary pain conditions such as temporomandibular disorder (TMD) and fibromyalgia syndrome (FMS), mild or chronic stress enhances pain. TMD and FMS often occur together, but the underlying mechanisms are unclear. The purpose of this study was to investigate the role of cholecystokinin (CCK) in the spinal cord in somatic hyperalgesia induced by orofacial inflammation combined with stress. Somatic hyperalgesia was detected by the thermal withdrawal latency and mechanical withdrawal threshold. The expression of CCK1 receptors, CCK2 receptors, ERK1/2 and p-ERK1/2 in the spinal cord was examined by Western blot. After the stimulation of orofacial inflammation combined with 3 day forced swim, the expression of CCK2 receptors and p-ERK1/2 protein in the L4-L5 spinal dorsal horn increased significantly, while the expression of CCK1 receptors and ERK1/2 protein remained unchanged. Intrathecal injection of the CCK2 receptor antagonist YM-022 or mitogen-activated protein kinase (MAPK) kinase (MEK) inhibitor PD98059 blocked somatic hyperalgesia induced by orofacial inflammation combined with stress. Intrathecal administration of the MEK inhibitor blocked somatic sensitization caused by the CCK receptor agonist CCK8. The CCK2 receptor antagonist YM-022 significantly reduced the expression of p-ERK1/2. These data indicate that upregulation of CCK2 receptors through the MAPK pathway contributes to somatic hyperalgesia in this comorbid pain model. Thus, CCK2 receptors and MAPK pathway may be potential targets for the treatment of TMD comorbid with FMS.

The Persistent Pain Transcriptome: Identification of Cells and Molecules Activated by Hyperalgesia.

During persistent pain, the dorsal spinal cord responds to painful inputs from the site of injury, but the molecular modulatory processes have not been comprehensively examined. Using transcriptomics and multiplex in situ hybridization, we identified the most highly regulated receptors and signaling molecules in rat dorsal spinal cord in peripheral inflammatory and post-surgical incisional pain models. We examined a time course of the response including acute (2 hours) and longer term (2 day) time points after peripheral injury representing the early onset and instantiation of hyperalgesic processes. From this analysis, we identify a key population of superficial dorsal spinal cord neurons marked by somatotopic upregulation of the opioid neuropeptide precursor prodynorphin, and 2 receptors: the neurokinin 1 receptor, and anaplastic lymphoma kinase. These alterations occur specifically in the glutamatergic subpopulation of superficial dynorphinergic neurons. In addition to specific neuronal gene regulation, both models showed induction of broad transcriptional signatures for tissue remodeling, synaptic rearrangement, and immune signaling defined by complement and interferon induction. These signatures were predominantly induced ipsilateral to tissue injury, implying linkage to primary afferent drive. We present a comprehensive set of gene regulatory events across 2 models that can be targeted for the development of non-opioid analgesics. PERSPECTIVE: The deadly impact of the opioid crisis and the need to replace morphine and other opioids in clinical practice is well recognized. Embedded within this research is an overarching goal of obtaining foundational knowledge from transcriptomics to search for non-opioid analgesic targets. Developing such analgesics would address unmet clinical needs.

Role of Peripheral Immune Cells for Development and Recovery of Chronic Pain.

Chronic neuropathic pain (CNP) is caused by a lesion or disease of the somatosensory nervous system. It affects ~8% of the general population and negatively impacts a person's level of functioning and quality of life. Its resistance to available pain therapies makes CNP a major unmet medical need. Immune cells have been shown to play a role for development, maintenance and recovery of CNP and therefore are attractive targets for novel pain therapies. In particular, in neuropathic mice and humans, microglia are activated in the dorsal horn and peripheral immune cells infiltrate the nervous system to promote chronic neuroinflammation and contribute to the initiation and progression of CNP. Importantly, immunity not only controls pain development and maintenance, but is also essential for pain resolution. In particular, regulatory T cells, a subpopulation of T lymphocytes with immune regulatory function, and macrophages were shown to be important contributors to pain recovery. In this review we summarize the interactions of the peripheral immune system with the nervous system and outline their contribution to the development and recovery of pain.

Immune Actions on the Peripheral Nervous System in Pain.

Pain can be induced by tissue injuries, diseases and infections. The interactions between the peripheral nervous system (PNS) and immune system are primary actions in pain sensitizations. In response to stimuli, nociceptors release various mediators from their terminals that potently activate and recruit immune cells, whereas infiltrated immune cells further promote sensitization of nociceptors and the transition from acute to chronic pain by producing cytokines, chemokines, lipid mediators and growth factors. Immune cells not only play roles in pain production but also contribute to PNS repair and pain resolution by secreting anti-inflammatory or analgesic effectors. Here, we discuss the distinct roles of four major types of immune cells (monocyte/macrophage, neutrophil, mast cell, and T cell) acting on the PNS during pain process. Integration of this current knowledge will enhance our understanding of cellular changes and molecular mechanisms underlying pain pathogenies, providing insights for developing new therapeutic strategies.

Immunological alterations in patients with chronic prostatitis/chronic pelvic pain syndrome and experimental autoimmune prostatitis model: A systematic review and meta-analysis.

BACKGROUND: As one of the most common conditions in urological outpatients, chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) puzzles many individuals because of its unclear etiology and lack of effective treatment. Recently, immunological alterations underpinning CP/CPPS have been extensively investigated. METHODS: The PubMed, Web of Science, Cochrane library, and EMBASE databases were used to search original articles on immune mediators in patients with CP/CPPS and in experimental autoimmune prostatitis (EAP) models through April 10, 2020. Standardized mean differences (SMD) were calculated to summarize the differences in immune mediator levels between groups. Funnel plot, Begg's funnel plot, Egger's regression test, and the sensitivity analysis were applied to determine and visualize the stability of our findings. RESULTS: A total of 34 original studies were included in the meta-analysis, including 24 studies on patients with CP/CPPS and 10 studies on EAP models. We found that TNF-α, IL-1ß, IL-6, and IL-8 were the four immune mediators that elevated in most of the samples derived from patients with CP/CPPS and the EAP models. The adjusted publication bias analysis indicated that publication bias was not existed, and the sensitivity analyses showed that the results were stable. CONCLUSIONS: Immune responses play significant roles during the pathogenesis of CP/CPPS by promoting intraprostatic inflammation. Our findings provide potential diagnostic and therapeutic targets for CP/CPPS patients.

Does Pollen Trigger Urological Chronic Pelvic Pain Syndrome Flares? A Case-Crossover Analysis in the Multidisciplinary Approach to the Study of Chronic Pelvic Pain Research Network.

PURPOSE: We sought to determine whether pollen triggers urological chronic pelvic pain syndrome flares. MATERIALS AND METHODS: We assessed flare status every 2 weeks for 1 year as part of the Multidisciplinary Approach to the Study of Chronic Pelvic Pain case-crossover analysis of flare triggers (NCT01098279). Flare symptoms, flare start date and exposures in the 3 days before a flare were queried for the first 3 flares and at 3 randomly selected nonflare times. These data were linked to daily pollen count by date and the first 3 digits of participants' zip codes. Pollen count in the 3 days before and day of a flare, as well as pollen rises past established thresholds, were compared to nonflare values by conditional logistic regression. Poisson regression was used to estimate flare rates in the 3 weeks following pollen rises past established thresholds in the full longitudinal study. Analyses were performed in all participants and separately in those who reported allergies or respiratory tract disorders. RESULTS: Although no associations were observed for daily pollen count and flare onset, positive associations were observed for pollen count rises past medium or higher thresholds in participants with allergies or respiratory tract disorders in the case-crossover (OR 1.31, 95% CI 1.04-1.66) and full longitudinal (RR 1.23, 95% CI 1.03-1.46) samples. CONCLUSIONS: We found some evidence to suggest that rising pollen count may trigger flares of urological chronic pelvic pain syndrome. If confirmed in future studies, these findings may help to inform flare pathophysiology, prevention and treatment, and control over the unpredictability of flares.

The Neuroimmunology of Chronic Pain: From Rodents to Humans.

Chronic pain, encompassing conditions, such as low back pain, arthritis, persistent post-surgical pain, fibromyalgia, and neuropathic pain disorders, is highly prevalent but remains poorly treated. The vast majority of therapeutics are directed solely at neurons, despite the fact that signaling between immune cells, glia, and neurons is now recognized as indispensable for the initiation and maintenance of chronic pain. This review highlights recent advances in understanding fundamental neuroimmune signaling mechanisms and novel therapeutic targets in rodent models of chronic pain. We further discuss new technological developments to study, diagnose, and quantify neuroimmune contributions to chronic pain in patient populations.

Enrichment of genomic pathways based on differential DNA methylation profiles associated with chronic musculoskeletal pain in older adults: An exploratory study.

Our study aimed to identify differentially methylated CpGs/regions and their enriched genomic pathways associated with underlying chronic musculoskeletal pain in older individuals. We recruited cognitively healthy older adults with (n = 20) and without (n = 9) self-reported musculoskeletal pain and collected DNA from peripheral blood that was analyzed using MethylationEPIC arrays. We identified 31,739 hypermethylated CpG and 10,811 hypomethylated CpG probes (ps ≤ 0.05). All CpG probes were clustered into 5966 regions, among which 600 regions were differentially methylated at p ≤ 0.05 level, including 294 hypermethylated regions and 306 hypomethylated regions (differentially methylated regions). Ingenuity pathway enrichment analysis revealed that the pain-related differentially methylated regions were enriched across multiple pathways. The top 10 canonical pathways were linked to cellular signaling processes related to immune responses (i.e. antigen presentation, programed cell death 1 receptor/PD-1 ligand 1, interleukin-4, OX40 signaling, T cell exhaustion, and apoptosis) and gamma-aminobutyric acid receptor signaling. Further, Weighted Gene Correlation Network Analysis revealed a comethylation network module in the pain group that was not preserved in the control group, where the hub gene was the cyclic adenosine monophosphate-dependent transcription factor ATF-2. Our preliminary findings provide new epigenetic insights into the role of aberrant immune signaling in musculoskeletal pain in older adults while further supporting involvement of dysfunctional GABAergic signaling mechanisms in chronic pain. Our findings need to be urgently replicated in larger cohorts as they may serve as a basis for developing and targeting future interventions.

TDAG8 deficiency reduces satellite glial number and pro-inflammatory macrophage number to relieve rheumatoid arthritis disease severity and chronic pain.

BACKGROUND: The autoimmune disease rheumatoid arthritis (RA) affects approximately 1% of the global population. RA is characterized with chronic joint inflammation and often associated with chronic pain. The imbalance of pro-inflammatory and anti-inflammatory macrophages is a feature of RA progression. Glial cells affecting neuronal sensitivity at both peripheral and central levels may also be important for RA progression and associated pain. Genetic variants in the T cell death-associated gene 8 (TDAG8) locus are found to associate with spondyloarthritis. TDAG8 was also found involved in RA disease progression and associated hyperalgesia in the RA mouse model. However, its modulation in RA remains unclear. METHODS: To address this question, we intra-articularly injected complete Freund's adjuvant (CFA) into TDAG8+/+, TDAG8-/- or wild-type mice, followed by pain behavioral tests. Joints and dorsal root ganglia were taken, sectioned, and stained with antibodies to observe the number of immune cells, macrophages, and satellite glial cells (SGCs). For compound treatments, compounds were intraperitoneally or orally administered weekly for 9 consecutive weeks after CFA injection. RESULTS: We demonstrated that TDAG8 deletion slightly reduced RA pain in the early phase but dramatically attenuated RA progression and pain in the chronic phase (> 7 weeks). TDAG8 deletion inhibited an increase in SGC number and inhibition of SGC function attenuated chronic phase of RA pain, so TDAG8 could regulate SGC number to control chronic pain. TDAG8 deletion also reduced M1 pro-inflammatory macrophage number at 12 weeks, contributing to the attenuation of chronic RA pain. Such results were further confirmed by using salicylanilide derivatives, CCL-2d or LCC-09, to suppress TDAG8 expression and function. CONCLUSIONS: This study demonstrates that TDAG8 deletion reduced SGC and M1 macrophage number to relieve RA disease severity and associated chronic pain. M1 macrophages are critical for the development and maintenance of RA disease and pain, but glial activation is also required for the chronic phase of RA pain.

Microbiota: a novel regulator of pain.

Among the various regulators of the nervous system, the gut microbiota has been recently described to have the potential to modulate neuronal cells activation. While bacteria-derived products can induce aversive responses and influence pain perception, recent work suggests that "abnormal" microbiota is associated with neurological diseases such as Alzheimer's, Parkinson's disease or autism spectrum disorder (ASD). Here we review how the gut microbiota modulates afferent sensory neurons function and pain, highlighting the role of the microbiota/gut/brain axis in the control of behaviors and neurological diseases. We outline the changes in gut microbiota, known as dysbiosis, and their influence on painful gastrointestinal disorders. Furthermore, both direct host/microbiota interaction that implicates activation of "pain-sensing" neurons by metabolites, or indirect communication via immune activation is discussed. Finally, treatment options targeting the gut microbiota, including pre- or probiotics, will be proposed. Further studies on microbiota/nervous system interaction should lead to the identification of novel microbial ligands and host receptor-targeted drugs, which could ultimately improve chronic pain management and well-being.

Smoking Associated T-Cell Imbalance in Patients With Chronic Pain.

INTRODUCTION: Smoking is associated with several diseases and affects the immune system. Recently, published data demonstrate an involvement of T helper 17 cells (Th17) and regulatory T cells (Tregs) in the pathogenesis of chronic pain and pain intensity. The role of these T-cell subsets in smoking patients with chronic pain is nebulous so far. We therefore analyzed Th17 cells and Tregs in smokers and nonsmokers with chronic pain. METHODS: Analyses of T-cell subsets, mRNA expression and T-cell related cytokine profiles were done in 44 patients with chronic pain. Twenty-two of these patients were smokers. Numbers of T-cell subsets were quantified by flow cytometry. mRNA expression of the Th17- (RAR-related orphan receptor gamma) and Treg (forkhead box protein P3)-specific transcription factors was determined by quantitative real-time PCR, and levels of cytokines were measured by Human Cytokine Multiplex Immunoassay. RESULTS: Compared to nonsmokers, smokers showed significantly enhanced pain levels. On cellular basis, the number of pro-inflammatory Th17 cells (smokers: 2.2 ± 2.5% vs. nonsmokers: 0.5 ± 0.4%; p = .04) was increased, whereas the number of anti-inflammatory Tregs (smokers: 2.5 ± 0.9% vs. nonsmokers: 3.1 ± 1.1%; p = .02) was significantly decreased, resulting in an altered Th17/Treg ratio (Th17/Treg ratio: 0.9 ± 1.0 in smokers vs. 0.2 ± 0.1 in nonsmokers; p < .01). These findings were confirmed by quantitative real-time PCR. Analyses of cytokines revealed only marginal changes. CONCLUSIONS: In patients with chronic pain, smoking is associated with enhanced pain levels together with an imbalance of the Th17/Treg ratio. The shift of the Th17/Treg ratio toward inflammation may explain in part the increased pain intensity in these patients. IMPLICATIONS: Smoking is associated with increased pain levels and a pro-inflammatory Th17/Treg shift. The altered Th17/Treg ratio in smoking patients with chronic pain may partly explain their increased pain intensity. GERMAN CLINICAL TRIAL REGISTER (DRKS): Registration Trial DRKS00005954.

LPA receptor signaling as a therapeutic target for radical treatment of neuropathic pain and fibromyalgia.

Since the first discovery that the bioactive lipid, lysophosphatidic acid (LPA) and LPA1 receptor signaling play a role in the initiation of neuropathic pain (NeuP), accumulated reports have supported the original findings and extended the study toward possible therapeutic applications. The present review describes beneficial roles of LPA receptor signaling in a variety of chronic pain, such as peripheral NeuP induced by nerve injury, chemotherapy and diabetes, central NeuP induced by cerebral ischemia with hemorrhage and spinal cord injury, and fibromyalgia-like wide spread pain induced by repeated cold, psychological and muscular acidic stress. Emerging mechanistic findings are the feed-forward amplification of LPA production through LPA1, LPA3 and microglia and the evidence for maintenance of chronic pain by LPA receptor signaling.

TNFR2 promotes Treg-mediated recovery from neuropathic pain across sexes.

Tumor necrosis factor receptor 2 (TNFR2) is a transmembrane receptor that is linked to immune modulation and tissue regeneration. Here, we show that TNFR2 essentially promotes long-term pain resolution independently of sex. Genetic deletion of TNFR2 resulted in impaired neuronal regeneration and chronic nonresolving pain after chronic constriction injury (CCI). Further, pharmacological activation of TNFR2 using the TNFR2 agonist EHD2-sc-mTNFR2 in mice with chronic neuropathic pain promoted long-lasting pain recovery. TNFR2 agonist treatment reduced neuronal injury, alleviated peripheral and central inflammation, and promoted repolarization of central nervous system (CNS)-infiltrating myeloid cells into an antiinflammatory/reparative phenotype. Depletion of regulatory T cells (Tregs) delayed spontaneous pain recovery and abolished the therapeutic effect of EHD2-sc-mTNFR2 This study therefore reveals a function of TNFR2 in neuropathic pain recovery and demonstrates that both TNFR2 signaling and Tregs are essential for pain recovery after CCI. Therefore, therapeutic strategies based on the concept of enhancing TNFR2 signaling could be developed into a nonopioid therapy for the treatment of chronic neuropathic pain.

Inhibition of COX-2 alleviates lumbar spinal stenosis-induced chronic mechanical allodynia in rats.

Chronic low back pain due to lumbar spinal stenosis (LSS) is common, costly, mechanistically complex, and clinically challenging. However, the factors and mechanisms causing and mediating chronic pain induced by cauda equina compression remain unclear. Here, we examined the role of cyclooxygenase (COX)-2 in infiltrated macrophages, a key mediator of inflammation, in chronic neuropathic pain by LSS using an animal model. LSS was induced in adult male rats by cauda equina compression procedure using a silicone block within the epidural spaces of L5-L6 vertebrae. Locomotor deficit was observed after compression and mechanical allodynia was developed progressively for 4 weeks after injury. A number of macrophage were also infiltrated into the spinal parenchyma and cauda equina and COX-2 was expressed in infiltrated macrophages at 28 days after cauda equina compression. The administration of COX-2 inhibitors, celecoxib and MPO-0029, significantly alleviated LSS-induced chronic mechanical allodynia and inhibited the mRNA expression of inflammatory mediators such as tnf-α, Il-1ß, il-6, and inos. Furthermore, COX-2 inhibitors significantly reduced prostaglandin E2 production. These results demonstrated the role of COX-2 in LSS-induced chronic neuropathic pain and suggest that the regulation of COX-2 can be considered as a therapeutic target to relive neuropathic pain.

Effect of alcohol on chronic pelvic pain and prostatic inflammation in a mouse model of experimental autoimmune prostatitis.

BACKGROUND: Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) is a prevalent disease of the urogenital system. Alcohol has been reported to be closely related to CP/CPPS. Thus, we intended to verify the role of alcohol in CP/CPPS and determine the underlying mechanism. METHODS: We induced experimental autoimmune prostatitis (EAP) mouse model by intradermally injecting a mixture of prostate antigens (PAgs) and complete Freund's adjuvant on days 0 and 28. Mice were treated with alcohol (control-alcohol and EAP-alcohol groups) or vehicle (control-vehicle, and EAP-vehicle groups) from day 32 to 42. Forty-two days after PAg injection, the pathological appearance of the prostate tissues was evaluated, and histological analyses of the prostate were performed. Chronic pelvic pain was assessed by applying von Frey filaments to the lower abdomen. Proinflammatory cytokines were detected by enzyme-linked immunosorbent assay tests. Then, we explored the effects of the NLRP3 inhibitor MCC950 on chronic pelvic pain and prostatic inflammation in this model. RESULTS: Histological analyses showed diffuse inflammation in the stromal tissues that were characterized by severe infiltration of neutrophils and mononuclear cells in mice in the EAP-alcohol group compared with EAP-vehicle group. Chronic pain tests showed that the response frequency was significantly increased using a von Frey filament at forces of 0.4, 1.0, and 4.0 g in EAP-alcohol group compared with EAP-vehicle (P < .05). The levels of proinflammatory cytokines, including interferon (IFN)-γ, tumor necrosis factor (TNF)-α, IL-17, and IL-1ß were all significantly elevated in EAP-alcohol group compared with the EAP-vehicle group (P < .05). However, between the control-alcohol and control-vehicle groups, chronic pain tests, histological assays, and cytokine determinations showed no differences. Furthermore, our results demonstrated that MCC950 could decrease the expression level of NLRP3 inflammasome-related proteins including NLRP3, ASC, and caspase-1. The chronic pain tests, histological assays, and cytokine determinations showed that MCC950 could attenuate the chronic pain and prostatic inflammation through the inhibition of the NLRP3 inflammasome. CONCLUSIONS: This study indicated that alcohol could aggravate the severity of prostatic inflammation in EAP model though activating the NLRP3 inflammasome. Furthermore, the role of MCC950 in inhibiting NLRP3 inflammasome and decreasing IL-1ß secretion to alleviate EAP severity may show that it is a promising therapeutic agent for CP/CPPS.

Effects of photobiomodulation therapy on inflammatory mediators in patients with chronic non-specific low back pain: Protocol for a randomized placebo-controlled trial.

INTRODUCTION: Low back pain (LBP) is ranked as one of the most prevalent health conditions. It is likely that some inflammatory mediators could be associated with pain and disability in these patients. Photobiomodulation therapy (PBMT) is a non-pharmacological therapy often used in patients with LBP and one of the possible mechanisms of action of therapy is modulate inflammatory mediators. However, to date there are no studies that evaluated the effects of PBMT on the levels of inflammatory mediators in patients with LBP. The aim of this study is to evaluate the acute effects of PBMT on systemic levels of inflammatory mediators and pain intensity in patients with chronic non-specific low back pain. METHODS AND ANALYSIS: This is a prospectively registered, two-arm randomized placebo-controlled trial with blinded patients, assessors and therapists. Eighteen patients with chronic non-specific LBP will be randomized into 2 groups: placebo or active PBMT. The treatment will be provided in a single session. The primary outcome will be levels of prostaglandin E2 (PGE2). The secondary outcomes will be levels of necrosis factor alpha (TNF-α), interleukin 6 (IL-6) and pain intensity. Biochemical and clinical outcomes will be measured at baseline and 15 minutes after the single treatment session. DISCUSSION: Despite PBMT be used in musculoskeletal disorders such as LBP, to the best of our knowledge this is the first study that will investigate a possible biological mechanism behind the positive clinical effects of PBMT on non-specific chronic low back pain. ETHICS AND DISSEMINATION: The study was approved by the Regional Research Ethics Committee. The results will be disseminated through publication in peer-reviewed international journal and conferences. TRIAL REGISTRATION NUMBER: NCT03859505.

Active immunisation targeting nerve growth factor attenuates chronic pain behaviour in murine osteoarthritis.

OBJECTIVES: Nerve growth factor (NGF) has emerged as a key driver of pain in osteoarthritis (OA) and antibodies to NGF are potent analgesics in human disease. Here, we validate a novel vaccine strategy to generate anti-NGF antibodies for reversal of pain behaviour in a surgical model of OA. METHODS: Virus-like particles were derived from the cucumber mosaic virus (CuMV) and coupled to expressed recombinant NGF to create the vaccine. 10-week-old male mice underwent partial meniscectomy to induce OA or sham-surgery. Spontaneous pain behaviour was measured by Linton incapacitance and OA severity was quantified using OARSI histological scoring. Mice (experimental and a sentinel cohort) were inoculated with CuMVttNGF (Vax) or CuMVttctrl (Mock) either before surgery or once pain was established. Efficacy of anti-NGF from the plasma of sentinel vaccinated mice was measured in vitro using a neurite outgrowth assay in PC12 cells. RESULTS: Anti-NGF titres were readily detectable in the vaccinated but not mock vaccinated mice. Regular boosting with fresh vaccine was required to maintain anti-NGF titres as measured in the sentinel cohort. Both prophylactic and therapeutic vaccination demonstrated a reversal of pain behaviour by incapacitance testing, and a meta-analysis of the two studies showing analgesia at peak anti-NGF titres was highly statistically significant. Serum anti-NGF was able to inhibit neurite outgrowth equivalent to around 150 ug/mL of recombinant monoclonal antibody. CONCLUSIONS: This study demonstrates therapeutic efficacy of a novel NGF vaccine strategy that reversibly alleviates spontaneous pain behaviour in surgically induced murine OA.

A nanoparticle-coupled T2 peptide induces immune tolerance and ameliorates chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) in mice model.

Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) is a complex disease of unclear etiology. Precise treatment of CP/CPPS is not available due to lack of specific cause; however, autoimmunity is the most valid theory. We develop a new treatment strategy that involves synthesis and coupling of biodegradable nanoparticles to antigenic T2 peptide to induce immune tolerance in CP/CPPS mice models. A total of 50 male C57BL/6 mice were randomized into five groups, that is, naïve, Model, PLGA-PEMA, PLGA-PEMA-OVA323-339 , and PLGA-PEMA-T2 group. All groups except naïve were injected subcutaneously on day 0 with 0.2 mL of T2 peptide with CFA to generate valid CP/CPPS models. After successful induction of CP/CPPS, Model group, PLGA-PEMA, PLGA-PEMA-OVA, and PLGA-PEMA-T2 groups were treated with 0.15 mL of normal saline, 0.2 mg of PLGA-PEMA and PLG-PEMA-T2 and 0.3 mg PLGA-PEMA-OVA nanoparticles, respectively, on day 28. Hematoxylin and eosin staining, and ELISA were used to evaluate the variation in CP/CPPS manifestations and seral level of IL-10 in each group. Pain threshold and voiding behavior were also recorded for every group. Mice treated with PLGA-PEMA-T2 exhibited enhanced pain threshold, reduced urine frequency, and prostate pathology. Furthermore, serum level of inflammatory mediators (TNF-α and CRP) were reduced and anti-inflammatory IL-10 was enhanced in PLGA-PEMA-T2 group as compared to other groups. Our results demonstrate that PLGA-PEMA-T2 nanoparticle ameliorates disease manifestations in CP/CPPS mice models and upregulates IL-10 which is essential for tolerance induction. This strategy highlights the new therapeutic approach utilizing biodegradable nanoparticles for the treatment of CP/CPPS.