Genome-wide association study of pain sensitivity assessed by questionnaire and the cold pressor test

Pan-cancer analysis identifies EIPR1 as a potential prognostic and immunological biomarker for lung adenocarcinoma and its functional validation

BACKGROUND

EARP and GARP complex-interacting protein 1 (EIPR1) may be a new oncogene in tumors, influencing the prognosis and invasion of cancer. However, a systematic analysis of the function of EIPR1 in various cancers remains vacant. Thus, we proceeded with a comprehensive analysis to ascertain the role of EIPR1 among various cancers.

METHODS

We explored EIPR1 expression in pan-cancer, and its association with clinical stage, survival, gene mutations and methylation by the TIMER 2.0, GEPIA2, cBioPortal, and UALCAN. The protein-protein interaction (PPI) network, immune infiltration, and immune checkpoint assessments of EIPR1 was performed using the STRING and SangerBox. The role of EIPR1 expression in lung adenocarcinoma (LUAD) was explored by the R software. The impact of EIPR1 expression on LUAD progression was studied through in vitro assays.

RESULTS

EIPR1 was overexpressed in most cancers and revealed as a potential prognostic biomarker in tumors, involving in tumorigenesis by affecting its methylation and gene mutations. The immune infiltration and immune checkpoints of tumors were related to the expression of EIPR1. Additionally, EIPR1 expression affected the survival, diagnosis, clinicopathological features, tumor microenvironment, and drug sensitivity of LUAD patients. Validation studies demonstrated that EIPR1 knockdown suppressed the malignant growth, invasion, and migration of LUAD cells.

CONCLUSIONS

This study delivers an extensive landscape for the oncogenesis and immunological characteristics of EIPR1, which reveals that EIPR1 may serve as a potential biological target for future prognosis and immune treatment in tumors, especially in LUAD.

Exploring the genetic influences on equine analgesic efficacy through genome-wide association analysis of ranked pain responses

Multimodal analgesic administration is a promising strategy for mitigating side effects typically associated with analgesia; nevertheless, variation in analgesic effectiveness still poses a considerable safety concern for both horses and veterinarians. Pharmacogenomic studies have started delving into genetic influences on varying drug effectiveness and related side effects. However, current findings have narrow implications and are limited in their ability to individualize analgesic dosages in horses. Hydromorphone and detomidine were administered to a cohort of 48 horses at standardized time intervals, with dosage rates recorded. Analgesic effectiveness was scored (1-3) based on pain response to dura penetration during cerebrospinal fluid centesis. Genome-wide association (GWA) analyses identified two SNVs passing the nominal significance threshold (P < 1 ×10-5) in association with analgesic effectiveness. One SNV identified on chromosome 27 (rs1142378599) is contained within the LOC100630731 disintegrin and metalloproteinase domain-containing protein 5 gene. The second identified SNV is an intergenic variant located on chromosome 29 (rs3430772468) These SNVs accounted for 26.11 % and 31.72 % of explained variation in analgesic effectiveness respectively, with all eight of the horses with the lowest analgesic effectiveness expressing the A/C genotype at rs3430772468, with six of which also expressing the C/T genotype at rs1142872965. Whilst highlighting the multifactorial nature of analgesic efficacy, this study serves as an important step in the application of genome-wide approaches to better understand genetic factors underpinning commonly observed variation in analgesic effectiveness in horses, with the goal of tailoring analgesic dosage to minimize commonly observed side effects and improve the outcomes of equine pain management.

Impact of Propranolol and Psychologically Informed Intervention on Pain Sensitivity: Secondary Analysis from the Biopsychosocial Influence on Shoulder Pain Preclinical Randomized Trial

Purpose

Measures of pain sensitivity have potential relevance for patient care. We previously identified a subgroup of people at risk for ongoing pain characterized by genetic AND psychological factors. Here, we report planned secondary analyses examining the effect of personalized interventions on pain sensitivity outcomes.

Patients and Methods

Two hundred and sixty-one healthy individuals with the COMT SNP rs6269 AA genotype and Pain Catastrophizing Scale scores of 5 or higher received exercise-induced muscle injury, followed by a randomly assigned treatment: (1) general education and placebo; (2) personalized psychological intervention and placebo; (3) general education and propranolol; or (4) personalized psychological intervention and propranolol. Pain sensitivity outcomes (pressure pain thresholds (PPT), suprathreshold heat rating, temporal summation, and conditioned pain modulation efficiency) were compared using a mixed effect model to examine difference among groups, adjusted for age, sex and race.

Results

No main effects for group assignment were noted (p > 0.05 for all), when considered as 4 groups or 2 collapsed groups (ie propranolol vs placebo or personalized psychologic vs general education). Interaction terms were then entered into our models in an exploratory fashion. For PPT outcomes interactions were noted for, sex and time, and race and time (p<0.015). For temporal summation outcomes, interactions were noted for sex and group and race and group (p < 0.015).

Conclusion

Results indicated no statistically reliable changes in pain sensitivity when considering matched vs unmatched treatment groups. Caution is needed in this interpretation given that the trial was not powered to specifically identify these differences. Exploratory analysis of interactions among ethnic/racial and gender identities by treatment, however, showed the potential for differential effects for specific pain sensitivity measures. Significant interactions across modalities suggest analysis of higher order interactions/intersectionality could be of great interest for testing efficacy of personalized interventions in future trials.

Trajectories of cold but not mechanical sensitivity correspond with disability trajectories after whiplash injury

ABSTRACT

Developmental trajectories for neck disability after whiplash injury have been identified. Their relationship to cold and mechanical sensitivity trajectories is not known. We aimed to (1) identify recovery trajectories of cold and mechanical sensitivity, (2) explore their codevelopment with disability trajectories, (3) identify predictors of sensitivity trajectories, and (4) explore codevelopment of cold and mechanical sensitivity trajectories. Participants (n = 233) were assessed at <1, 3, 6, and 12 months after whiplash injury. Outcomes were cold pain detection threshold (CPT at neck), pressure pain detection thresholds (PPT, neck C5, and tibialis anterior), and the Neck Disability Index. We used group-based trajectory models to identify postinjury recovery trajectories and multinominal logistic regression to explore associations between baseline characteristics and trajectory membership. We identified the following trajectory groups: CPT (low [50.0%], moderate [29.7%], and high [20.4%] sensitivity); PPT C5 (low [10.8%] and high [89.2%] sensitivity); and PPT tibialis anterior (low [23.9%], moderate [39.0%], and high [37.1%] sensitivity); all were stable over the 12 months. There was good correspondence between disability and cold sensitivity trajectory groups but not for mechanical sensitivity; cold and mechanical sensitivity trajectories were not well associated. Higher baseline pain predicted membership of the high cold sensitivity trajectory (RR 1.27, 95% CI 1.01-1.59) and hyperarousal symptoms predicted membership of the moderate cold sensitivity trajectory (RR 1.17, 95% CI 1.01-1.36). We found no associations between baseline characteristics and mechanical sensitivity. There is an interplay between cold allodynia, pain, and hyperarousal symptoms in development of ongoing disability after whiplash injury. Different mechanisms likely underlie cold and mechanical sensitivity.

Osteocytes contribute to sex-specific differences in osteoarthritic pain

Osteoarthritic (OA) pain affects 18% of females and 9.6% of males aged over 60 worldwide, with 62% of all OA patients being women. The molecular drivers of sex-based differences in OA are unknown. Bone is intricately coupled with the sensory nervous system and one of the only joint tissues known to show changes that correlate with patient pain in OA. There are fundamental sex differences in pain sensation and bone biology which may be intrinsic to OA disease progression, however these differences are vastly under researched. We have utilised three data sets to investigate the hypothesis that potential mediators responsible for sex dependent pain mechanisms displayed in OA are derived from mechanically stimulated osteocytes. Our published dataset of the in vitro human osteocyte mechanosome was independently compared with published data from, sex-based gene expression differences in human long bone, the sex-based gene expression differences during the skeletal maturation of the mouse osteocyte transcriptome and sex specific OA risk factors and effector genes in a large human GWAS. 80 of the 377 sex-specific genes identified in the mouse osteocyte transcriptome were mechanically regulated in osteocytes with enrichment associated with neural crest migration and axon extension, and DISEASES analysis enrichment for the rheumatoid arthritis pathway. 3861 mechanically regulated osteocytic genes displayed sex-specific differences in human long bone with enrichment for genes associated with the synapse, sensory perception of pain, axon guidance, immune responses, distal peripheral sensory neuropathy, sensory neuropathy, and poor wound healing. 32 of 77 effector genes and 1 of 3 female specific OA risk factor genes identified in the human GWAS were differentially expressed in the osteocyte mechanosome and male and female bone. This analysis lends support to the hypothesis that mechanically regulated genes in osteocytes could influence sex specific differences in osteoarthritic pain and highlights pain pathways with approved drugs that could potentially treat elevated pain susceptibility in females with OA.

Advancing Pain Understanding and Drug Discovery: Insights from Preclinical Models and Recent Research Findings

Despite major advancements in our understanding of its fundamental causes, pain-both acute and chronic-remains a serious health concern. Various preclinical investigations utilizing diverse animal, cellular, and alternative models are required and frequently demanded by regulatory approval bodies to bridge the gap between the lab and the clinic. Investigating naturally occurring painful disorders can speed up medication development at the preclinical and clinical levels by illuminating molecular pathways. A wide range of animal models related to pain have been developed to elucidate pathophysiological mechanisms and aid in identifying novel targets for treatment. Pain sometimes drugs fail clinically, causing high translational costs due to poor selection and the use of preclinical tools and reporting. To improve the study of pain in a clinical context, researchers have been creating innovative models over the past few decades that better represent pathological pain conditions. In this paper, we provide a summary of traditional animal models, including rodents, cellular models, human volunteers, and alternative models, as well as the specific characteristics of pain diseases they model. However, a more rigorous approach to preclinical research and cutting-edge analgesic technologies may be necessary to successfully create novel analgesics. The research highlights from this review emphasize new opportunities to develop research that includes animals and non-animals using proven methods pertinent to comprehending and treating human suffering. This review highlights the value of using a variety of modern pain models in animals before human trials. These models can help us understand the different mechanisms behind various pain types. This will ultimately lead to the development of more effective pain medications.

Association Between Eye Color and Postoperative Pain in Female Patients With Symptomatic Irreversible Pulpitis in Mandibular Molars: A Prospective, Parallel-Group, Observational Study

Background: Current evidence indicates that some phenotypic characteristics, such as eye or hair color, might be associated with the experience of pain. We, therefore, compared the anesthetic success rate of inferior alveolar nerve block (IANB) and postoperative pain scores between light eyes and dark eyes in female patients who experienced symptomatic irreversible pulpitis (SIP) in a mandibular molar. Methods: This prospective, parallel-group, observational study was registered with ClinicalTrials.gov (NCT06206304). A total of 110 adult female patients who experienced moderate or severe pain with SIP participated in this study. All patients received IANB with 4% articaine with 1:100.000 epinephrine. Endodontic access cavity preparation was initiated after confirmation of IANB. Pain during treatment was recorded by using a Visual Analog Scale. Anesthetic success was recorded as "none" or "mild" pain. Root canal treatment was performed, with standardized protocols. Postoperative pain scores were also recorded at 24, 48, and 72 h and 7 days after treatment. Statistical analyses of the data were performed using the independent t-test, repeated measures ANOVA test, and Pearson's chi-square test. The statistical significance level was set at 0.05. Results: No significant differences were found in the success rate of IANB and postoperative pain scores between light- and dark-eyed patients at any time point (p > 0.05). The success rate of IANB was 72.73% and 67.27% for light- and dark-eyed patients, respectively. Conclusion: Pain scores decreased significantly after RCT in both groups on all days (p < 0.05). No significant differences were found in the success rate of IANB and postop pain scores between light- and dark-eyed female patients who experienced SIP in a mandibular molar. Trial Registration: ClinicalTrials.gov identifier: NCT06206304.

Red-Haired People's Altered Responsiveness to Pain, Analgesics, and Hypnotics: Myth or Fact?-A Narrative Review

Red hair has been linked to altered sensitivity to pain, analgesics, and hypnotics. This alteration may be impacted by variants in the melanocortin-1 receptor (MC1R) gene, which are mainly found in redheads. The aim of this narrative review was to explore and present the current state of knowledge on red hair and its plausible associations with altered responsiveness to pain, analgesics, and hypnotics. Structured searches in the PubMed, CINAHL Complete, and Scopus electronic databases were conducted. Evidence suggests that women with red hair have an increased sensitivity to pain. Conversely, data also indicate a higher pain tolerance in homozygous carriers of MC1R variant alleles. Varied responses to analgesia have been reported, with both increased analgesic responsiveness in homozygous carriers of MC1R variant alleles and less analgesia in redheads. Data indicate an increased need for hypnotics in redheads. However, failed attempts to find statistical associations between red hair and altered responsiveness to hypnotics are also evident. Even though there seems to be an association between red hair and an altered responsiveness to pain, analgesics, and/or hypnotics, the results of this narrative review are inconclusive. Further research studies with larger populations and MC1R testing are needed.

Water temperature during the cold pressor test: A scoping review

The cold pressor test (CPT) is a commonly used method to induce pain and stress in experimental settings. Previous research has found that the temperature of the water used in the test significantly affects outcome measures such as pain tolerance. Variations in CPT protocols, specifically regarding temperature, have been criticized. Hence, our objective is to investigate water temperature and associated methodological factors through a scoping review of the CPT in adults. Among 331 included trials, the most commonly reported temperature was 1°C (33.8°F). Reporting of the water temperature was adequate (93% of all trials), but a precise range within which the temperature was maintained was reported only in 27% of all trials. Pain measurement was the primary focus for most studies (90%), predominantly utilizing pain tolerance as the main outcome (78%). Water circulation was reported in 44% of studies, and 10% reported manually agitating the water. The most common maximum immersion time (i.e., ceiling time) was 180 s; notably, 64% of trials lacked information on participant awareness of this limit specification. The limb most immersed was the hand (76%). Overall, multiple methodological factors significantly impacting outcome measures were inconsistently implemented or reported. For future studies, we advocate for precise standardization of the water temperature used during the CPT. We suggest using 1°C (33.8°F), especially when assessing pain tolerance. A cooling apparatus allowing precise temperature control and continuous water circulation is advised. At the bare minimum, the temperature should be monitored continuously. While other decisions regarding the implementation of the CPT may differ depending on the specific aims of the respective study, it remains essential to standardize the water temperature and to provide a comprehensive report of the experimental protocol.

Enhanced harm detection following maternal separation: Transgenerational transmission and reversibility by inhaled amiloride

Early-life adversities are associated with altered defensive responses. Here, we demonstrate that the repeated cross-fostering (RCF) paradigm of early maternal separation is associated with enhancements of distinct homeostatic reactions: hyperventilation in response to hypercapnia and nociceptive sensitivity, among the first generation of RCF-exposed animals, as well as among two successive generations of their normally reared offspring, through matrilineal transmission. Parallel enhancements of acid-sensing ion channel 1 (ASIC1), ASIC2, and ASIC3 messenger RNA transcripts were detected transgenerationally in central neurons, in the medulla oblongata, and in periaqueductal gray matter of RCF-lineage animals. A single, nebulized dose of the ASIC-antagonist amiloride renormalized respiratory and nociceptive responsiveness across the entire RCF lineage. These findings reveal how, following an early-life adversity, a biological memory reducible to a molecular sensor unfolds, shaping adaptation mechanisms over three generations. Our findings are entwined with multiple correlates of human anxiety and pain conditions and suggest nebulized amiloride as a therapeutic avenue.

A systematic review of genome-wide association studies for pain, nociception, neuropathy, and pain treatment responses

ABSTRACT

Pain is the leading cause of disability worldwide, imposing an enormous burden on personal health and society. Pain is a multifactorial and multidimensional problem. Currently, there is (some) evidence that genetic factors could partially explain individual susceptibility to pain and interpersonal differences in pain treatment response. To better understand the underlying genetic mechanisms of pain, we systematically reviewed and summarized genome-wide association studies (GWASes) investigating the associations between genetic variants and pain/pain-related phenotypes in humans. We reviewed 57 full-text articles and identified 30 loci reported in more than 1 study. To check whether genes described in this review are associated with (other) pain phenotypes, we searched 2 pain genetic databases, Human Pain Genetics Database and Mouse Pain Genetics Database. Six GWAS-identified genes/loci were also reported in those databases, mainly involved in neurological functions and inflammation. These findings demonstrate an important contribution of genetic factors to the risk of pain and pain-related phenotypes. However, replication studies with consistent phenotype definitions and sufficient statistical power are required to validate these pain-associated genes further. Our review also highlights the need for bioinformatic tools to elucidate the function of identified genes/loci. We believe that a better understanding of the genetic background of pain will shed light on the underlying biological mechanisms of pain and benefit patients by improving the clinical management of pain.

We need to talk: The urgent conversation on chronic pain, mental health, prescribing patterns and the opioid crisis

The opioid crisis’ pathways from first exposure onwards to eventual illnesses and fatalities are multiple, intertwined and difficult to dissect. Here, we offer a multidisciplinary appraisal of the relationships among mental health, chronic pain, prescribing patterns worldwide and the opioid crisis. Because the opioid crisis’ toll is especially harsh on young people, emphasis is given on data regarding the younger strata of the population. Because analgesic opioid prescription constitute a recognised entry point towards misuse, opioid use disorder, and ultimately overdose, prescribing patterns across different countries are examined as a modifiable hazard factor along these pathways of risk. Psychiatrists are called to play a more compelling role in this urgent conversation, as they are uniquely placed to provide synthesis and lead action among the different fields of knowledge and care that lie at the crossroads of the opioid crisis. Psychiatrists are also ideally positioned to gauge and disseminate the foundations for diagnosis and clinical management of mental conditions associated with chronic pain, including the identification of hazardous and protective factors. It is our hope to spark more interdisciplinary exchanges and encourage psychiatrists worldwide to become leaders in an urgent conversation with interlocutors from the clinical and basic sciences, policy makers and stakeholders including clients and their families.