Epidemiology of neuropathic pain: an analysis of prevalence and associated factors in UK Biobank

Methylcobalamin as a candidate for chronic peripheral neuropathic pain therapy: review of molecular pharmacology actiona

Chronic peripheral neuropathic pain therapy currently focuses on modulating neuroinflammatory conditions. Methylcobalamin (MeCbl), a neuroregenerative agent, modulates neuroinflammation. This review aimed to explore the molecular pharmacology action of MeCbl as a chronic peripheral neuropathic pain therapeutic agent. MeCbl plays a role in various cellular processes and may have therapeutic potential in neurodegenerative diseases. Intracellular MeCbl modulates inflammation by regulating the activity of T lymphocytes and natural killer cells as well as secretion of inflammatory cytokines, namely, tumor necrosis factor-α, interleukin-6, interleukin-1β, epidermal growth factor, and neuronal growth factor. MeCbl can reduce pain symptoms in chronic neuropathic pain conditions by decreasing excitation and hyperpolarization-induced ion channel activity in medium-sized dorsal root ganglion (DRG) neurons and the expression of transient receptor potential ankyrin 1, transient receptor potential cation channel subfamily M member 8, phosphorylated p38MAPK, transient receptor potential cation channel subfamily V members 1 and 4 in the DRG, and the voltage-gated sodium channel in axons.

Preclinical Evaluation of Soluble Epoxide Hydrolase Inhibitor AMHDU against Neuropathic Pain

Inhibition of soluble epoxide hydrolase (sEH) is a promising therapeutic strategy for treating neuropathic pain. These inhibitors effectively reduce diabetic neuropathic pain and inflammation induced by Freund's adjuvant which makes them a suitable alternative to traditional opioids. This study showcased the notable analgesic effects of compound AMHDU (1,1'-(hexane-1,6-diyl)bis(3-((adamantan-1-yl)methyl)urea)) in both inflammatory and diabetic neuropathy models. While lacking anti-inflammatory properties in a paw edema model, AMHDU is comparable to celecoxib as an analgesic in 30 mg/kg dose administrated by intraperitoneal injection. In a diabetic tactile allodynia model, AMHDU showed a prominent analgesic activity in 10 mg/kg intraperitoneal dose (p < 0.05). The effect is comparable to that of gabapentin, but without the risk of dependence due to a different mechanism of action. Low acute oral toxicity (>2000 mg/kg) and a high therapeutic index makes AMHDU a promising candidate for further structure optimization and preclinical evaluation.

Multi-Omics Profiles of Chronic Low Back Pain and Fibromyalgia - Study Protocol

Background

Chronic low back pain (CLBP) and fibromyalgia (FM) are leading causes of suffering, disability, and social costs. Current pharmacological treatments do not target molecular mechanisms driving CLBP and FM, and no validated biomarkers are available, hampering the development of effective therapeutics. Omics research has the potential to substantially advance our ability to develop mechanism-specific therapeutics by identifying pathways involved in the pathophysiology of CLBP and FM, and facilitate the development of diagnostic, predictive, and prognostic biomarkers. We will conduct a blood and urine multi-omics study in comprehensively phenotyped and clinically characterized patients with CLBP and FM. Our aims are to identify molecular pathways potentially involved in the pathophysiology of CLBP and FM that would shift the focus of research to the development of target-specific therapeutics, and identify candidate diagnostic, predictive, and prognostic biomarkers.

Methods

We are conducting a prospective cohort study of adults ≥18 years of age with CLBP (n=100) and FM (n=100), and pain-free controls (n=200). Phenotyping measures include demographics, medication use, pain-related clinical characteristics, physical function, neuropathiccomponents (quantitative sensory tests and DN4 questionnaire), pain facilitation (temporal summation), and psychosocial function as moderator. Blood and urine samples are collected to analyze metabolomics, lipidomics and proteomics. We will integrate the overall omics data to identify common mechanisms and pathways, and associate multi-omics profiles to pain-related clinical characteristics, physical function, indicators of neuropathic pain, and pain facilitation, with psychosocial variables as moderators.

Discussion

Our study addresses the need for a better understanding of the molecular mechanisms underlying chronic low back pain and fibromyalgia. Using a multi-omics approach, we hope to identify converging evidence for potential targets of future therapeutic developments, as well as promising candidate biomarkers for further investigation by biomarker validation studies. We believe that accurate patient phenotyping will be essential for the discovery process, as both conditions are characterized by high heterogeneity and complexity, likely rendering molecular mechanisms phenotype specific.

Identification and validation of aging-related genes in neuropathic pain using bioinformatics

Background

Neuropathic pain (NP) is a debilitating and refractory chronic pain with a higher prevalence especially in elderly patients. Cell senescence considered a key pathogenic factor in NP. The objective of this research is to discover genes associated with aging in peripheral blood of individuals with NP using bioinformatics techniques.

Methods

Two cohorts (GSE124272 and GSE150408) containing peripheral blood samples of NP were downloaded from the GEO database. By merging the two cohorts, differentially expressed aging-related genes (DE-ARGs) were obtained by intersection with aging-related genes. The potential biological mechanisms of DE-ARGs were further analyzed through GO and KEGG. Three machine learning methods, namely, LASSO, SVM-RFE, and Random Forest, were utilized to identify diagnostic biomarkers. A Nomogram model was developed to assess their diagnostic accuracy. The validation of biomarker expression and diagnostic effectiveness was conducted in three distinct pain cohorts. The CIBERSORT algorithm was employed to evaluate the immune cell composition in the peripheral blood of patients with NP and investigate its association with the expression of diagnostic biomarkers.

Results

This study identified a total of 24 DE-ARGs, mainly enriched in "Chemokine signaling pathway," "Inflammatory mediator regulation of TRP channels," "HIF-1 signaling pathway" and "FOXO signaling pathway". Three machine learning algorithms identified a total of four diagnostic biomarkers (CEBPA, CEACAM1, BTG3 and IL-1R1) with good diagnostic performance and the similar expression difference trend in different types of pain cohorts. The expression levels of CEACAM1 and IL-1R1 exhibit a positive correlation with the percentage of neutrophils.

Conclusion

Using machine learning techniques, our research identified four diagnostic biomarkers related to aging in peripheral blood, providing innovative approaches for the diagnosis and treatment of NP.

Association between chronic pain and risk of cardiometabolic multimorbidity: a prospective cohort study

BACKGROUND

Although chronic pain was deleteriously related to single cardiometabolic diseases, the relationship between chronic pain and cardiometabolic multimorbidity remains unclear. The purpose of this study was to investigate the association between chronic pain with the risk of cardiometabolic multimorbidity.

METHODS

A prospective cohort study included 452 818 participants who were free of cardiometabolic multimorbidity at baseline. Chronic pain was assessed in diverse anatomical sites including the head, face, neck/shoulder, stomach/abdominal area, back, hip and knee or 'all over the body'. Participants were classified into six groups according to the amount of chronic pain sites: no chronic pain, chronic pain at one, two, three and four or more sites, and those reporting pain 'all over the body'. Cardiometabolic multimorbidity was defined as the occurrence of at least two cardiometabolic diseases, involving type 2 diabetes, ischaemic heart disease and stroke.

RESULTS

After a median follow-up of 13.7 years, 4445 participants developed cardiometabolic multimorbidity. Compared with individuals without chronic pain, those experiencing chronic pain in four or more sites were associated with a 1.82-fold (HR: 1.82, 95% CI: 1.61, 2.06) higher risk of cardiometabolic multimorbidity. Pain distributed 'all over the body' was associated with a 59% (HR: 1.59, 95% CI: 1.30, 1.93) increased risk of cardiometabolic multimorbidity Additionally, individuals who had chronic pain in both the head and stomach/abdomen showed the highest risk with cardiometabolic multimorbidity (HR: 1.88, 95% CI: 1.60, 2.20).

CONCLUSIONS

Our findings suggested that there was an elevated risk of cardiometabolic multimorbidity associated with an increased amount of chronic pain sites.

Design of Mixed Medicinal Plants, Rich in Polyphenols, Vitamins B, and Palmitoylethanolamide-Based Supplement to Help Reduce Nerve Pain: A Preclinical Study

Neuropathy affects 7-10% of the general population and is caused by a lesion or disease of the somatosensory system. The limitations of current therapies highlight the necessity of a new innovative approach to treating neuropathic pain (NP) based on the close correlation between oxidative stress, inflammatory process, and antioxidant action. The advantageous outcomes of a novel combination composed of Hop extract, Propolis, Ginkgo Biloba, Vitamin B, and palmitoylethanolamide (PEA) used as a treatment was evaluated in this study. To assess the absorption and biodistribution of the combination, its bioavailability was first examined in a 3D intestinal barrier model that replicated intestinal absorption. Further, a 3D nerve tissue model was developed to study the biological impacts of the combination during the essential pathways involved in NP. Our findings show that the combination could cross the intestinal barrier and reach the peripheral nervous system, where it modulates the oxidative stress, inflammation levels, and myelination mechanism (increased NRG, MPZ, ERB, and p75 levels) under Schwann cells damaging. This study proves the effectiveness of Ginkgo Biloba, Propolis, Hop extract, Vitamin B, and PEA in avoiding nerve damage and suggests a potential alternative nutraceutical treatment for NP and neuropathies.

Peripheral neuropathic pain: supporting patients with self-management

Peripheral neuropathic pain is a complex condition that can adversely affect people's quality of life. Alongside pharmacological interventions, nurses can support patients to self-manage their pain using non-pharmacological interventions such as lifestyle changes and exercise. To do this effectively, nurses should be able to recognise the signs and symptoms of peripheral neuropathic pain and be able to educate patients on appropriate self-management approaches. It is important that nurses provide education, advice and information in a way that patients can understand and check this understanding. This article provides an overview of how nurses can support patients to self-manage peripheral neuropathic pain by using various non-pharmacological interventions.

The Spiritual Aspect of Pain: An Integrative Review

Pain is an unpleasant sensory and emotional experience that affects individuals in various ways involving biological, psychological, social, and spiritual aspects. There is currently no comprehensive treatment that effectively addresses all aspects of pain. This integrative review aimed to analyze the spiritual aspect of pain relief. Following the specified methodological criteria, a total of 20 articles were selected. There evidenced a lack of spiritual care provided by healthcare professionals, even though its correlation with pain and its potential benefits have been widely demonstrated in the literature. Fortunately, some patients put into practice existential and religious tools to self-control and cope with their pain, although not always with a successful response.

Introduction to a special issue on big data and pain

This special issue comprised 7 articles from leaders in the field that focus on "big pain data", the large datasets and the associated methods for data analysis that are currently emerging in pain research. This collection of articles highlights the power and potential as well as points of caution that multi-disciplinary research utilising big data and their associated methods and interpretations present for pain research.

Cerebrospinal fluid immune cells appear similar across neuropathic and non-neuropathic pain conditions

Background

Microglia have been implicated in the pathophysiology of neuropathic pain. Here, we sought to investigate whether cerebrospinal fluid (CSF) might be used as a proxy-measure of microglial activation in human participants.

Methods

We preformed fluorescence-activated cell sorting (FACS) of CSF immune cell populations derived from individuals who experienced pain with neuropathic features. We sorted CD4+, CD8+ T cells and monocytes and analyzed their transcriptome using RNA sequencing. We also performed Cellular Indexing of Transcriptomes and Epitopes (CITE) sequencing to characterize the expression of all CSF immune cells in a patient with postherpetic neuralgia and in a patient with neuropathic pain after failed back surgery.

Results

Immune cell numbers and phenotypes were not obviously different between individuals regardless of the etiology of their pain. This was true when examining our own dataset, as well as when comparing it to previously published single-cell RNA sequencing data of human CSF. In all instances, CSF monocytes showed expression of myeloid cell markers commonly associated with microglia ( P2RY12, TMEM119 and OLFML3), which will make it difficult to ascertain the origin of CSF proteins: do they derive directly from circulating CSF monocytes or could some originate in spinal cord microglia in the parenchyma?

Conclusions

We conclude that it will not be straightforward to use CSF as a biomarker for microglial function in humans.

Genetics of diabetes-associated microvascular complications

Diabetes is associated with excess morbidity and mortality due to both micro- and macrovascular complications, as well as a range of non-classical comorbidities. Diabetes-associated microvascular complications are those considered most closely related to hyperglycaemia in a causal manner. However, some individuals with hyperglycaemia (even those with severe hyperglycaemia) do not develop microvascular diseases, which, together with evidence of co-occurrence of microvascular diseases in families, suggests a role for genetics. While genome-wide association studies (GWASs) produced firm evidence of multiple genetic variants underlying differential susceptibility to type 1 and type 2 diabetes, genetic determinants of microvascular complications are mostly suggestive. Identified susceptibility variants of diabetic kidney disease (DKD) in type 2 diabetes mirror variants underlying chronic kidney disease (CKD) in individuals without diabetes. As for retinopathy and neuropathy, reported risk variants currently lack large-scale replication. The reported associations between type 2 diabetes risk variants and microvascular complications may be explained by hyperglycaemia. More extensive phenotyping, along with adjustments for unmeasured confounding, including both early (fetal) and late-life (hyperglycaemia, hypertension, etc.) environmental factors, are urgently needed to understand the genetics of microvascular complications. Finally, genetic variants associated with reduced glycolysis, mitochondrial dysfunction and DNA damage and sustained cell regeneration may protect against microvascular complications, illustrating the utility of studies in individuals who have escaped these complications.

Big data, big consortia, and pain: UK Biobank, PAINSTORM, and DOLORisk

Chronic pain (CP) is a common and often debilitating disorder that has major social and economic impacts. A subset of patients develop CP that significantly interferes with their activities of daily living and requires a high level of healthcare support. The challenge for treating physicians is in preventing the onset of refractory CP or effectively managing existing pain. To be able to do this, it is necessary to understand the risk factors, both genetic and environmental, for the onset of CP and response to treatment, as well as the pathogenesis of the disorder, which is highly heterogenous. However, studies of CP, particularly pain with neuropathic characteristics, have been hindered by a lack of consensus on phenotyping and data collection, making comparisons difficult. Furthermore, existing cohorts have suffered from small sample sizes meaning that analyses, especially genome-wide association studies, are insufficiently powered. The key to overcoming these issues is through the creation of large consortia such as DOLORisk and PAINSTORM and biorepositories, such as UK Biobank, where a common approach can be taken to CP phenotyping, which allows harmonisation across different cohorts and in turn increased study power. This review describes the approach that was used for studying neuropathic pain in DOLORisk and how this has informed current projects such as PAINSTORM, the rephenotyping of UK Biobank, and other endeavours. Moreover, an overview is provided of the outputs from these studies and the lessons learnt for future projects.