Quantitative proteomic analysis of human peripheral nerves from subjects with type 2 diabetes

Insights into the molecular underpinning of type 2 diabetes complications

Type 2 diabetes (T2D) complications pose a significant global health challenge. Omics technologies have been employed to investigate these complications and identify the biological pathways involved. In this review, we focus on four major T2D complications: diabetic kidney disease, diabetic retinopathy, diabetic neuropathy, and cardiovascular complications. We discuss advancements in omics research, summarizing findings from genetic, epigenomic, transcriptomic, proteomic, and metabolomic studies across different ancestries and disease-relevant tissues. We stress the importance of integrating multi-omics techniques to elucidate the biological mechanisms underlying T2D complications and advocate for ancestrally diverse studies. Ultimately, these insights will improve risk prediction for T2D complications and inform translation strategies.

Refinement of Protein Extraction Protocols for Human Peripheral Nerve Tissue

Our aim was to establish an effective method for protein extraction from freshly frozen human peripheral nerves, determine the minimum amount required for consistent protein extraction outcomes, and assess which method produced the highest number of protein identities. Five extraction methods were compared using 8 M urea and Ripa buffer using either the Bullet Blender or Bioruptor. Out of the total 2619 identified proteins, protein extraction using the Ripa buffer combined with either Bioruptor or Bullet Blender resulted in the identification of 1582 (60%) and 1615 (62%) proteins, respectively. In contrast, using 8 M urea and Bioruptor for protein extraction resulted in 1022 proteins (39%), whereas employing Bullet Blender yielded 1446 proteins (55%). Sample amounts, ranging from 0.6 to 10 mg, were prepared with consistent protein extraction outcome obtained for samples ≥1.2 mg. Combining Ripa and 8 M urea with Bullet Blender increased protein identification to 2126 (81%). Proteins were classified by their cell components, molecular functions, and biological processes. Furthermore, a subclassification of proteins involved in the extracellular matrix (ECM) was introduced. We recommend the use of Ripa buffer, in combination with 8 M urea and Bullet Blender for extracting proteins from fresh-frozen human nerves weighing ≥1.2 mg.

Diabetic Peripheral Neuropathy: Emerging Treatments of Neuropathic Pain and Novel Diagnostic Methods

BACKGROUND

Diabetic peripheral neuropathy (DPN) is a prevalent and debilitating complication of diabetes, often leading to severe neuropathic pain. Although other diabetes-related complications have witnessed a surge of emerging treatments in recent years, DPN has seen minimal progression. This stagnation stems from various factors, including insensitive diagnostic methods and inadequate treatment options for neuropathic pain.

METHODS

In this comprehensive review, we highlight promising novel diagnostic techniques for assessing DPN, elucidating their development, strengths, and limitations, and assessing their potential as future reliable clinical biomarkers and endpoints. In addition, we delve into the most promising emerging pharmacological and mechanistic treatments for managing neuropathic pain, an area currently characterized by inadequate pain relief and a notable burden of side effects.

RESULTS

Skin biopsies, corneal confocal microscopy, transcutaneous electrical stimulation, blood-derived biomarkers, and multi-omics emerge as some of the most promising new techniques, while low-dose naltrexone, selective sodium-channel blockers, calcitonin gene-related peptide antibodies, and angiotensin type 2 receptor antagonists emerge as some of the most promising new drug candidates.

CONCLUSION

Our review concludes that although several promising diagnostic modalities and emerging treatments exist, an ongoing need persists for the further development of sensitive diagnostic tools and mechanism-based, personalized treatment approaches.

Serum levels of biomarkers related to severity staging of Raynaud's phenomenon, neurosensory manifestations, and vibration exposure in patients with hand-arm vibration injury

Our aim was to explore possible relationships between serum levels of biomarkers in patients with hand-arm vibration injury in relation to the severity of the vascular, i.e., Raynaud's phenomenon (RP), and neurosensory manifestations, the current exposure level, and the duration of exposure. This study was of case series design and involved 92 patients diagnosed with hand-arm vibration injury. Jonckheere's trend test was used to assess any association between serum levels of biomarkers and RP as well as neurosensory manifestations, graded by the International Consensus Criteria. Generalized linear models with adjustment for possible confounders were also used for associations between serum levels of biomarkers and; (1) severity of RP recorded as the extent of finger blanching calculated with Griffin score, (2) vibration perception thresholds, (3) magnitude of current exposure as [A(8); (m/s2)] value, and (4) the duration of exposure in years. Serum levels of thrombomodulin, von Willebrand factor, calcitonin gene related peptide (CGRP), heat shock protein 27, and caspase-3 were positively associated with severity of RP. Serum levels of CGRP were positively associated with the neurosensory component. No associations with exposure were shown for these biomarkers. For Intercellular adhesion molecule 1 and monocyte chemoattractant protein 1, no associations were found with neither severity nor exposure. Levels of serum biomarkers associated with endothelial injury or dysfunction, inflammation, vasodilation, neuroprotection, and apoptosis were positively associated with the severity of hand-arm vibration injury.

Serum biomarkers in patients with hand-arm vibration injury and in controls

Hand-arm vibration injury is a well-known occupational disorder that affects many workers globally. The diagnosis is based mainly on quantitative psychophysical tests and medical history. Typical manifestations of hand-arm vibration injury entail episodes of finger blanching, Raynaud's phenomenon (RP) and sensorineural symptoms from affected nerve fibres and mechanoreceptors in the skin. Differences in serum levels of 17 different biomarkers between 92 patients with hand-arm vibration injury and 51 controls were analysed. Patients with hand-arm vibration injury entailing RP and sensorineural manifestations showed elevated levels of biomarkers associated with endothelial injury or dysfunction, inflammation, vaso- or neuroprotective compensatory, or apoptotic mechanisms: intercellular adhesion molecule-1 (ICAM-1), monocyte chemoattractant protein-1 (MCP-1); thrombomodulin (TM), heat shock protein 27 (HSP27); von Willebrand factor, calcitonin gene-related peptide (CGRP) and caspase-3. This study adds important knowledge on pathophysiological mechanisms that can contribute to the implementation of a more objective method for diagnosis of hand-arm vibration injury.

The Dynamics of Nerve Degeneration and Regeneration in a Healthy Milieu and in Diabetes

Appropriate animal models, mimicking conditions of both health and disease, are needed to understand not only the biology and the physiology of neurons and other cells under normal conditions but also under stress conditions, like nerve injuries and neuropathy. In such conditions, understanding how genes and different factors are activated through the well-orchestrated programs in neurons and other related cells is crucial. Knowledge about key players associated with nerve regeneration intended for axonal outgrowth, migration of Schwann cells with respect to suitable substrates, invasion of macrophages, appropriate conditioning of extracellular matrix, activation of fibroblasts, formation of endothelial cells and blood vessels, and activation of other players in healthy and diabetic conditions is relevant. Appropriate physical and chemical attractions and repulsions are needed for an optimal and directed regeneration and are investigated in various nerve injury and repair/reconstruction models using healthy and diabetic rat models with relevant blood glucose levels. Understanding dynamic processes constantly occurring in neuropathies, like diabetic neuropathy, with concomitant degeneration and regeneration, requires advanced technology and bioinformatics for an integrated view of the behavior of different cell types based on genomics, transcriptomics, proteomics, and imaging at different visualization levels. Single-cell-transcriptional profile analysis of different cells may reveal any heterogeneity among key players in peripheral nerves in health and disease.

Patient reported symptoms and disabilities before and after neuroma surgery: a register-based study

Residual problems may occur from neuroma despite surgery. In a 12-month follow-up study using national register data, symptoms, and disabilities related to surgical methods and sex were evaluated in patients surgically treated for a neuroma. Among 196 identified patients (55% men; lower age; preoperative response rate 20%), neurolysis for nerve tethering/scar formation was the most used surgical method (41%; more frequent in women) irrespective of affected nerve. Similar preoperative symptoms were seen in patients, where different surgical methods were performed. Pain on load was the dominating symptom preoperatively. Women scored higher preoperatively at pain on motion without load, weakness and QuickDASH. Pain on load and numbness/tingling in fingers transiently improved. The ability to perform daily activities was better after nerve repair/reconstruction/transposition than after neurolysis. Regression analysis, adjusted for age, sex, and affected nerve, showed no association between surgical method and pain on load, tingling/numbness in fingers, or ability to perform daily activities. Neuroma, despite surgery, causes residual problems, affecting daily life. Choice of surgical method is not strongly related to pre- or postoperative symptoms. Neurolysis has similar outcome as other surgical methods. Women have more preoperative symptoms and disabilities than men. Future research would benefit from a neuroma-specific ICD-code, leading to a more precise identification of patients.

Neuromas cause severe residual problems at long-term despite surgery

Pain, and disabilities after neuroma surgery, using patient reported outcome measurements (PROMs), were evaluated by QuickDASH and a specific Hand Questionnaire (HQ-8). The 69 responding individuals (response rate 61%; 59% women; 41% men; median follow up 51 months) reported high QuickDASH score, pain on load, cold sensitivity, ability to perform daily activities and sleeping difficulties. Individuals reporting impaired ability to perform daily activities and sleeping problems had higher scores for pain, stiffness, weakness, numbness/tingling, cold sensitivity and QuickDASH. Only 17% of individuals reported no limitations at all. No differences were observed between sexes. Surgical methods did not influence outcome. Symptoms and disabilities correlated moderately-strongly to each other and to ability to perform regular daily activities as well as to sleeping difficulties. Pain, cold sensitivity, sleeping difficulties and limitation to perform daily activities were associated to higher QuickDASH. A weak association was found between follow up time and QuickDASH score as well as pain on load, but not cold sensitivity. A major nerve injury was frequent among those with limitations during work/performing other regular daily activities. Despite surgical treatment, neuromas cause residual problems, which affect the capacity to perform daily activities and ability to sleep with limited improvement in long-term.

LncRNAs regulate ferroptosis to affect diabetes and its complications

Worldwide, the rapid increase in the incidence of diabetes and its complications poses a serious threat to human health. Ferroptosis, which is a new nonapoptotic form of cell death, has been proven to be closely related to the occurrence and development of diabetes and its complications. In recent years, lncRNAs have been confirmed to be involved in the occurrence and development of diabetes and play an important role in regulating ferroptosis. An increasing number of studies have shown that lncRNAs can affect the occurrence and development of diabetes and its complications by regulating ferroptosis. Therefore, lncRNAs have great potential as therapeutic targets for regulating ferroptosis-mediated diabetes and its complications. This paper reviewed the potential impact and regulatory mechanism of ferroptosis on diabetes and its complications, focusing on the effects of lncRNAs on the occurrence and development of ferroptosis-mediated diabetes and its complications and the regulation of ferroptosis-inducing reactive oxygen species, the key ferroptosis regulator Nrf2 and the NF-κB signaling pathway to provide new therapeutic strategies for the development of lncRNA-regulated ferroptosis-targeted drugs to treat diabetes.

Carpal Tunnel Syndrome and Diabetes—A Comprehensive Review

Carpal tunnel syndrome (CTS) is the most common compression neuropathy in the general population and is frequently encountered among individuals with type 1 and 2 diabetes. The reason(s) why a peripheral nerve trunk in individuals with diabetes is more susceptible to nerve compression is still not completely clarified, but both biochemical and structural changes in the peripheral nerve are probably implicated. In particular, individuals with neuropathy, irrespective of aetiology, have a higher risk of peripheral nerve compression disorders, as reflected among individuals with diabetic neuropathy. Diagnosis of CTS in individuals with diabetes should be carefully evaluated; detailed case history, thorough clinical examination, and electrophysiological examination is recommended. Individuals with diabetes and CTS benefit from surgery to the same extent as otherwise healthy individuals with CTS. In the present review, we describe pathophysiological aspects of the nerve compression disorder CTS in relation to diabetes, current data contributing to the explanation of the increased risk for CTS in individuals with diabetes, as well as diagnostic methods, treatment options, and prognosis of CTS in diabetes.

Carpal Tunnel Syndrome and Ulnar Nerve Entrapment at the Elbow Are Not Associated With Plasma Levels of Caspase-3, Caspase-8 or HSP27

Background

Nerve compression disorders, such as carpal tunnel syndrome (CTS) and ulnar entrapment at the elbow (UNE), may be associated with apoptosis and neuroprotective mechanisms in the peripheral nerve that may be detected by biomarkers in the blood. The relationships between CTS and UNE and two biomarkers of apoptosis, i.e., caspase-3 and caspase-8, and the neuroprotective factor Heat Shock Protein 27 (HSP27) in plasma were examined in a population-based cohort.

Method

The biomarkers caspase-3, caspase-8 and HSP27 were measured in plasma at inclusion of 4,284 study participants aged 46-68 years in the population-based Malmö Diet and Cancer study (MDCS). End-point retrieval was made from national registers concerning CTS and UNE. Independent t-test was used to examine the association between caspase-3, caspase-8 and HSP27 plasma levels and incidence of CTS and UNE. Cox proportional hazards regression was used to investigate if plasma levels of caspase-3, caspase-8 and HSP27 affected time to diagnosis of CTS or UNE.

Results

During the mean follow-up time of 22 years, 189/4,284 (4%) participants were diagnosed with CTS and 42/4,284 (1%) were diagnosed with UNE. No associations were found between incident CTS or UNE and the biomarkers caspase-3, caspase-8 and HSP27 in plasma.

Conclusion

The apoptotic biomarkers caspase-3 and caspase-8 and the neuroprotective factor HSP27 in plasma, factors conceivably related to a nerve injury, are not associated with the nerve compression disorders CTS and UNE in a general population.