PAIN®Pub Date : 2025-05-13DOI: 10.1097/j.pain.0000000000003607
Cristina D Peterson,Carolyn A Fairbanks
{"title":"Reduced motivation to seek opioid reward in preclinical studies of pain: a commentary on Lueptow et al.","authors":"Cristina D Peterson,Carolyn A Fairbanks","doi":"10.1097/j.pain.0000000000003607","DOIUrl":"https://doi.org/10.1097/j.pain.0000000000003607","url":null,"abstract":"","PeriodicalId":19921,"journal":{"name":"PAIN®","volume":"14 1","pages":""},"PeriodicalIF":7.4,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143992037","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Opioid dose trajectories and associations with opioid- and nonopioid-related emergency department presentations and hospital admissions.","authors":"Ting Xia,Louisa Picco,Bosco Rowland,Grant Russell,Jenni Ilomaki,Nadine Andrew,Samanta Lalic,Rachelle Buchbinder,Dan I Lubman,Suzanne Nielsen","doi":"10.1097/j.pain.0000000000003638","DOIUrl":"https://doi.org/10.1097/j.pain.0000000000003638","url":null,"abstract":"Opioid deprescribing is a key strategy for reducing opioid-related adverse effects. However, although deprescribing can be associated with clinical benefits, international studies suggest that rapid dose reduction in those on long-term opioids may be associated with poorer outcomes. This study examines the association between different opioid dose trajectories and emergency department presentations or hospital admissions related to substance use and mental health in Victoria, Australia. This is a retrospective cohort study of individuals receiving long-term opioids (at least 90 days) between January 1, 2018 and May 31, 2022, over an 18-month follow-up period. Deidentified primary care data were linked with hospital records from 3 metropolitan hospital networks in Victoria. Trajectory modelling was used to identify different prescription opioid dose patterns. Poisson regression modelling was used to examine associations between opioid dose trajectories and clinical outcomes. In total, 39,767 patients were included in the study, and 5 different opioid dose trajectories were identified, including 2 that showed a decreasing pattern. After adjusting for covariates, the incidence risk ratio of mental health-related emergency department presentations increased by 35.0% (95% confidence interval [CI] 1.108-1.645) in the \"gradual decrease from intermediate dose\" group, and 30.8% (95% CI 1.098-1.558) in the \"rapid decrease from low dose\" group, respectively, compared with the medium-stable dose trajectory. The \"gradual decrease from intermediate dose\" trajectory also had an increased risk of hospital admissions related to substance use (incidence risk ratio 1.568, 95% CI 1.266-1.942). A decreasing opioid dose trajectories in patients receiving long-term opioids was associated with an elevated risk of adverse clinical outcomes.","PeriodicalId":19921,"journal":{"name":"PAIN®","volume":"75 1","pages":""},"PeriodicalIF":7.4,"publicationDate":"2025-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143945535","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
PAIN®Pub Date : 2025-05-09DOI: 10.1097/j.pain.0000000000003616
Airam Vivanco-Estela,Sanderson Araujo da Rocha,Daniela Escobar-Espinal,Gabriela Gonçalves Bálico,Robert M Caudle,Francisco S Guimaraes,Elaine Del-Bel,Glauce Crivelaro Nascimento
{"title":"Sex-related differences in cannabidiol's antinociceptive efficacy in a trigeminal neuralgia rodent model.","authors":"Airam Vivanco-Estela,Sanderson Araujo da Rocha,Daniela Escobar-Espinal,Gabriela Gonçalves Bálico,Robert M Caudle,Francisco S Guimaraes,Elaine Del-Bel,Glauce Crivelaro Nascimento","doi":"10.1097/j.pain.0000000000003616","DOIUrl":"https://doi.org/10.1097/j.pain.0000000000003616","url":null,"abstract":"Trigeminal neuralgia (TN) is a severe orofacial pain condition with sex-specific differences in pain responses. Standard treatments offer limited efficacy and significant side effects. We hypothesized that cannabidiol (CBD) alleviates TN-induced allodynia more effectively than carbamazepine in a sex- and dose-dependent manner through neuroimmune mechanisms, including modulation of glia, Fos protein expression, and oxidative stress in the ventrolateral periaqueductal gray (vlPAG) and spinal trigeminal nucleus caudalis (Sp5c). In an infraorbital nerve constriction model, mechanical allodynia was evaluated in male and female Wistar-Hannover rats. Our study demonstrates the potent antinociceptive effects of CBD in reducing mechanical allodynia in both male and female models of trigeminal neuralgia, without affecting locomotor activity, unlike carbamazepine. Although CBD's analgesic effects were consistent across sexes, carbamazepine showed sex-dependent efficacy. Cannabidiol's effects on Fos-B were region- and sex-dependent: it inhibited Fos-B in the Sp5c in both sexes but only in males in the vlPAG, suggesting sexually dimorphic activation of descendent pain circuits. Cannabidiol prevented superoxide oxidation in the vlPAG in both sexes, with effects on microglia and astrocytes at similar doses, suggesting that glial cells produce the oxidative stress inhibited by CBD. In the Sp5c, CBD modulated Fos-B, superoxide oxidation, microglia, and astrocytes in both sexes, indicating a possible lack of sexual dimorphism in this region. These results highlight CBD's efficacy in managing TN by modulating ascending and descending nociceptive pathways. Beyond its neuronal effects, CBD's analgesic actions in TN may also involve significant modulation of glial cell activity, underscoring the complexity of its therapeutic mechanisms.","PeriodicalId":19921,"journal":{"name":"PAIN®","volume":"96 1","pages":""},"PeriodicalIF":7.4,"publicationDate":"2025-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143945510","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
PAIN®Pub Date : 2025-05-09DOI: 10.1097/j.pain.0000000000003622
Orna Gera,Karni Ginzburg,Noga Gur,Ruth Defrin
{"title":"Effects of acute stress exposure on pain sensitivity: the role of individual stress responsiveness and orientation to pain and stress.","authors":"Orna Gera,Karni Ginzburg,Noga Gur,Ruth Defrin","doi":"10.1097/j.pain.0000000000003622","DOIUrl":"https://doi.org/10.1097/j.pain.0000000000003622","url":null,"abstract":"Acute stress exposure has been reported to result in stress-induced hypoalgesia (SI-hypo), hyperalgesia (SI-hyper), or no response (SI-NR). The inconsistency may stem from individual variability in acute stress response and/or individual orientation to stress and pain, factors not commonly examined. We aimed to identify patterns of SI-hypo and SI-hyper, their relation to stress responsiveness, and the moderating effects of stress and pain orientations. Healthy participants (n = 133) were exposed to acute stress via the Montreal Imaging Stress Task (MIST). Heat-pain threshold (HPT) was measured before and after the MIST. Changes in state anxiety pre-post MIST indicated stress responsiveness, and stress and pain orientations were evaluated via Global Perceived Stress (GPS) and Fear of Pain (FOP), respectively. Autonomic variables and salivary cortisol were examined for manipulation check. The MIST induced three pattens of effect on HPT: 27.8% of participants exhibited SI-hypo, 24.8% exhibited SI-hyper, and 47.4% SI-NR. Higher stress responsiveness was associated with greater HPT change. FOP and GPS significantly moderated the association between stress responsiveness and HPT change; the higher the stress response, the greater SI-hypo among individuals with low FOP and among individuals with high GPS. Furthermore, the higher the stress response, the greater SI-hyper among individuals with high FOP. Thus, individual variability in the effects of stress on pain sensitivity may be conditioned by stress responsiveness, and by stress and pain orientations. As increased distress can contribute to, and exacerbate, chronic pain, FOP and GPS may serve as treatment targets for the prevention and amelioration of chronic pain.","PeriodicalId":19921,"journal":{"name":"PAIN®","volume":"113 1","pages":""},"PeriodicalIF":7.4,"publicationDate":"2025-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143945459","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Clinical features and functional analysis of novel SCN9A variants causing congenital insensitivity to pain.","authors":"Peter Sparber,Nikolai Zernov,Tatiana Markova,Inna Sharkova,Irina Nikishina,Valeria Matkava,Fedor Konovalov,Philipp Sviridov,Victoria Zabnenkova,Oxana Ryzhkova,Olga Shchagina,Vyacheslav Tabakov,Mikhail Skoblov","doi":"10.1097/j.pain.0000000000003628","DOIUrl":"https://doi.org/10.1097/j.pain.0000000000003628","url":null,"abstract":"Pain perception is a fundamental protective mechanism that enables us to detect noxious stimuli. With a focus on finding treatments for pain, the molecular mechanisms and key players involved in pain perception are currently under intense study. Congenital insensitivity to pain is one of the rarest and most unusual pain disorders. One of the reasons of pure congenital absence of pain are pathogenic variants in the SCN9A gene, which encodes the α-subunit of the Nav1.7 voltage-gated sodium channel. To date, most of the described variants in SCN9A associated with congenital insensitivity to pain are biallelic frameshifting variants, and the extent to which splice-affecting variants contribute to this rare phenotype remains largely unknown. Here, we describe 4 novel variants in previously unreported patients with congenital insensitivity to pain, all carrying noncoding variants in a homozygous or compound-heterozygous state in the SCN9A gene. Functional analyses demonstrated that all variants affect mRNA splicing, leading to both out-of-frame and in-frame isoforms. In 1 case, a deep-intronic variant detected through whole-genome sequencing led to the inclusion of a pseudoexon in intron 9. Genotype-phenotype analysis did not reveal significant differences in phenotype severity among the patients, suggesting that in-frame shortening of the Nav1.7 protein completely disrupts its function. These findings broaden the understanding of SCN9A-related pain insensitivity and uncover the molecular mechanisms of novel noncoding variants in the SCN9A gene, which is crucial for the development of future tailored therapeutic approaches.","PeriodicalId":19921,"journal":{"name":"PAIN®","volume":"35 1","pages":""},"PeriodicalIF":7.4,"publicationDate":"2025-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143945511","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
PAIN®Pub Date : 2025-05-09DOI: 10.1097/j.pain.0000000000003645
Christopher J Miller,Warren B Bilker,Ian DeLorey,Charles E Argoff,Russell L Bell,Andrew Conroy,Jennifer S Gewandter,Ian Gilron,Jennifer A Haythornthwaite,Nathaniel P Katz,Tara McWilliams,Katherine N Theken,John T Farrar
{"title":"Minimum clinically important differences in acute pain: a patient-level re-analysis of randomized controlled analgesic trials submitted to the US Food and Drug Administration.","authors":"Christopher J Miller,Warren B Bilker,Ian DeLorey,Charles E Argoff,Russell L Bell,Andrew Conroy,Jennifer S Gewandter,Ian Gilron,Jennifer A Haythornthwaite,Nathaniel P Katz,Tara McWilliams,Katherine N Theken,John T Farrar","doi":"10.1097/j.pain.0000000000003645","DOIUrl":"https://doi.org/10.1097/j.pain.0000000000003645","url":null,"abstract":"The lack of established minimum clinically important differences in acute pain has made it challenging to interpret efficacy in analgesic trials. We performed a patient-level re-analysis of double-blind, placebo-controlled trials submitted to the US Food and Drug Administration to estimate minimum clinically important differences in acute postoperative pain. Trials were categorized by acute surgical pain model: dental extraction, bunionectomy, orthopedic surgery, and soft tissue surgery. Pain intensity was assessed using the 0 to 10 numeric rating scale (NRS) or 0 to 100 visual analog scale, with visual analog scale scores converted to NRS for analysis. To avoid misclassification from arbitrary thresholds on global impression of change or pain relief scales, meaningful pain relief was determined using the double-stopwatch technique, where patients actively indicated the times they experienced perceptible and meaningful relief. Across 29 trials, 9047 patients with moderate-to-severe baseline pain were included. Patients with severe baseline pain (NRS ≥7) reported meaningful relief at a higher absolute NRS and required larger absolute reductions in pain intensity than those with moderate baseline pain (NRS 4-<7). However, the percent reduction in pain at meaningful relief remained stable across baseline pain levels, suggesting patients assess meaningful relief in relative rather than absolute terms. No appreciable differences in the changes in pain at meaningful relief were observed by age, sex, drug, or route of administration. Receiver operating characteristic curve analysis identified a 50% reduction in pain intensity as a consistent and clinically meaningful threshold across surgical pain models, supporting its use as a standardized patient-centric metric for evaluating analgesic efficacy.","PeriodicalId":19921,"journal":{"name":"PAIN®","volume":"25 1","pages":""},"PeriodicalIF":7.4,"publicationDate":"2025-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143945537","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
PAIN®Pub Date : 2025-05-09DOI: 10.1097/j.pain.0000000000003618
Hassan A Karoam,Joel Bruss,Katharine Champoux,Marcelo Delboni Lemos,Isabelle Faillenot,Daniel Ciampi de Andrade,Kai Hwang,Emine Bayman,Jatin Vaidya,Evan M Gordon,Daniel Tranel,Joel C Geerling,Aaron D Boes
{"title":"Neuroanatomy and lesion networks of central poststroke pain.","authors":"Hassan A Karoam,Joel Bruss,Katharine Champoux,Marcelo Delboni Lemos,Isabelle Faillenot,Daniel Ciampi de Andrade,Kai Hwang,Emine Bayman,Jatin Vaidya,Evan M Gordon,Daniel Tranel,Joel C Geerling,Aaron D Boes","doi":"10.1097/j.pain.0000000000003618","DOIUrl":"https://doi.org/10.1097/j.pain.0000000000003618","url":null,"abstract":"Identifying lesion sites associated with central poststroke pain (CPSP) may facilitate targeted screening for early symptoms, possibly even paving the way for preventive measures and earlier treatment initiation. Here, we test the hypothesis that damage to a nociceptive pathway extending from the brainstem to the cerebral cortex, and including white matter tracts, is associated with CPSP. We investigated the lesion locations of 72 patients with CPSP relative to poststroke comparison subjects without pain (n = 123), divided into a discovery and independent validation data set. The study included three main analyses: (1) we compared lesion intersection with our a priori region of interest (ROI) between groups with and without CPSP, (2) we performed lesion-symptom mapping to evaluate whether lesions associated with CPSP localize to the a priori ROI, and (3) we used lesion network mapping to infer the broader structural and functional connectivity patterns associated with CPSP lesions. CPSP lesions overlapped the nociceptive pathway ROI to a greater extent than comparison lesions. Lesion-symptom mapping identified a CPSP-associated region overlapping with the ventrocaudal thalamus and adjacent white matter, which was located mostly within the a priori ROI. Lesion network mapping demonstrated that lesions associated with CPSP disrupt nodes and tracts of the nociceptive pathway ROI. Interestingly, the CPSP lesion network results demonstrated connectivity to intereffector nodes of the primary motor cortex, providing a novel link between CPSP and the somato-cognitive action network. Together, these findings indicate that CPSP can be conceptualized as a lesion-associated network disruption of the nociceptive pathway and somato-cognitive action network.","PeriodicalId":19921,"journal":{"name":"PAIN®","volume":"33 1","pages":""},"PeriodicalIF":7.4,"publicationDate":"2025-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143945509","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The bradykinin-1 receptor antagonist fulmetibant in patients with diabetic neuropathic pain: the randomized, crossover, placebo-controlled, double-blind, phase 2a BRADiNP study.","authors":"Brigitte Stemper,Stephanie Löwen,Achim Fritsch,Anja Hoffmann,Arnab Sarkar","doi":"10.1097/j.pain.0000000000003642","DOIUrl":"https://doi.org/10.1097/j.pain.0000000000003642","url":null,"abstract":"The BRADiNP study was a multicenter, randomized, double-blind, placebo-controlled, 2-treatment complete crossover study evaluating the efficacy and safety of the bradykinin 1 receptor antagonist fulmetibant in patients with diabetic neuropathic pain (DNP) (ClinicalTrials.gov NCT05219812). To be eligible for enrollment, patients had to be adults with type 1 or type 2 diabetes mellitus with painful distal symmetric sensorimotor neuropathy of >6 months' duration and neuropathic pain. After blinded washout of prior DNP treatment, patients were randomized 1:1 to start with either fulmetibant once daily or placebo in the first 4 weeks' treatment period and vice versa in the second period. The primary endpoint was the change from baseline in weekly mean 24-hour average pain intensity score at week 4. Seventy-nine participants were treated with fulmetibant (450 mg once daily), and 79 participants were treated with placebo; 75 participants completed treatment in both treatment periods. At week 4, the mean treatment difference was 0.07 (-0.170 to 0.314). Adverse events were mostly mild or moderate in severity and occurred in 51.3% of the treated participants (41.8% after treatment with fulmetibant and 32.9% after treatment with placebo). The results of this study show that preclinical efficacy seen with this bradykinin 1 receptor antagonist did not translate into a meaningful therapeutic approach for pain management in patients with DNP.","PeriodicalId":19921,"journal":{"name":"PAIN®","volume":"117 1","pages":""},"PeriodicalIF":7.4,"publicationDate":"2025-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143921001","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Exploring the presence of long COVID-like symptoms in patients with chronic pain: a large-scale internet-based cross-sectional study in Japan.","authors":"Saki Takaoka,Hanako Saito,Morihiko Kawate,Chisato Tanaka,Yihuan Wu,Shizuko Kosugi,Takashige Yamada,Takahiro Tabuchi,Kenta Wakaizumi","doi":"10.1097/j.pain.0000000000003643","DOIUrl":"https://doi.org/10.1097/j.pain.0000000000003643","url":null,"abstract":"Individuals with chronic pain not only endure the direct burden of pain but also experience various symptoms, including sleep disturbances and fatigue, which deteriorate their quality of life. Notably, these symptoms closely resemble those observed in \"long COVID,\" a prolonged health complication that can arise after coronavirus disease 2019 (COVID-19) infection. Because the similarities between chronic pain and long COVID remain unexplored, this study aimed to investigate their relationship using Japanese epidemiological data. Using the Japan COVID-19 and Society Internet Survey in 2022, which included 32,000 participants, we analyzed data on the presence of chronic pain, history of COVID-19 infection, and presence of 17 long COVID-like symptoms, including gastrointestinal upset, back pain, limb/joint pain, headache, chest pain, shortness of breath, dizziness, sleep disorder, hearing disorder, taste disorder, smell disorder, memory impairment, poor concentration, hair loss, decreased libido, fatigue, and cough. Individuals with history of COVID-19 experienced a significantly greater number of long COVID-like symptoms (median: 5) compared with those with neither COVID-19 nor chronic pain (median: 4, P < 0.001). Individuals with chronic pain alone and those with both COVID-19 and chronic pain exhibited an even greater number of symptoms (median: 8 and 9, respectively). In addition, individuals with chronic pain exhibited greater prevalence odds for 15 of the 17 symptoms than those with neither COVID-19 nor chronic pain (P < 0.001). Our findings indicate that long COVID-like symptoms are not specifically associated with COVID-19. Instead, the data suggest that chronic pain contributes as an independent risk factor for these symptoms.","PeriodicalId":19921,"journal":{"name":"PAIN®","volume":"19 1","pages":""},"PeriodicalIF":7.4,"publicationDate":"2025-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143920999","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
PAIN®Pub Date : 2025-05-06DOI: 10.1097/j.pain.0000000000003629
Richard J Berwick, Peyman Sahbaie, Grace Kenny, Tian-Zhi Guo, Harvey Neiland, David A Andersson, J David Clark, Patrick Mallon, Andreas Goebel
{"title":"Postacute COVID-19 syndrome and fibromyalgia syndrome are associated with anti-satellite glial cell IgG serum autoantibodies but only fibromyalgia syndrome serum-IgG is pronociceptive.","authors":"Richard J Berwick, Peyman Sahbaie, Grace Kenny, Tian-Zhi Guo, Harvey Neiland, David A Andersson, J David Clark, Patrick Mallon, Andreas Goebel","doi":"10.1097/j.pain.0000000000003629","DOIUrl":"https://doi.org/10.1097/j.pain.0000000000003629","url":null,"abstract":"<p><strong>Abstract: </strong>Postacute COVID-19 syndrome (PACS) describes the persistence of symptoms following severe acute respiratory syndrome coronavirus 2 clearance. PACS is sometimes associated with pain and fatigue resembling fibromyalgia syndrome (FMS). Severe FMS has recently been associated with pronociceptive immunoglobulin G (IgG) autoantibodies and anti-satellite glial cell (SGC) IgG autoreactivity, suggesting an autoimmune aetiology. We validated FMS-IgG passive transfer and then tested the hypothesis that PACS-patients, with high musculoskeletal pain and fatigue, harbour proalgesic and anti-SGC autoantibodies. PACS-patients with high pain and fatigue or people recently recovered from acute COVID-19 were recruited to the All-Ireland Infectious Diseases Study. We pooled serum from 18 patients per group and purified their serum-IgG. In addition, we obtained IgG from UK patients with FMS and healthy controls to confirm assay performance. Passive transfer experiments of IgG (8 mg/d) over 3 days were conducted using male (C57BL/6J) mice (n = 6 mice per group). We measured mechanical and cold hypersensitivities and grip strength. Injection of FMS-IgG elicited the previously described mouse phenotype in male rodents, including increased mechanical/cold hypersensitivities and reduced grip strength compared with control IgG, whereas pooled PACS-IgG was inert. Immunocytochemistry of primary-SGC-enriched cultures reproduced the increased staining of FMS-IgG over the control reported previously. Both IgG from patients with PACS and those recently recovered from COVID-19 stained strongly positive. We confirm the pronociceptive properties of FMS-IgG and demonstrate, in contrast, that PACS symptoms from our cohort, with severe pain and fatigue, are not transmissible through passive transfer to male rodents. Postacute COVID-19 syndrome pain is often localised, and stratification according to the widespread distribution of pain should be considered for future studies; recovered COVID-19 leaves a strong trace of anti-SGC autoreactivity.</p>","PeriodicalId":19921,"journal":{"name":"PAIN®","volume":" ","pages":""},"PeriodicalIF":5.9,"publicationDate":"2025-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144132707","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}