Increased levels of inflammatory factors are associated with severity of polyneuropathy in type 1 diabetes

Biomarkers and signaling pathways of diabetic nephropathy and peripheral neuropathy: possible therapeutic intervention of rutin and quercetin

Diabetic nephropathy and peripheral neuropathy are the two main complications of chronic diabetes that contribute to high morbidity and mortality. These conditions are characterized by the dysregulation of multiple molecular signaling pathways and the presence of specific biomarkers such as inflammatory cytokines, indicators of oxidative stress, and components of the renin-angiotensin system. In this review, we systematically collected and collated the relevant information from MEDLINE, EMBASE, ELSEVIER, PUBMED, GOOGLE, WEB OF SCIENCE, and SCOPUS databases. This review was conceived with primary objective of revealing the functions of these biomarkers and signaling pathways in the initiation and progression of diabetic nephropathy and peripheral neuropathy. We also highlighted the potential therapeutic effectiveness of rutin and quercetin, two plant-derived flavonoids known for their antioxidant and anti-inflammatory properties. The findings of our study demonstrated that both flavonoids can regulate important disease-promoting systems, such as inflammation, oxidative stress, and dysregulation of the renin-angiotensin system. Importantly, rutin and quercetin have shown protective benefits against nephropathy and neuropathy in diabetic animal models, suggesting them as potential therapeutic agents. These findings provide a solid foundation for further comprehensive investigations and clinical trials to evaluate the potential of rutin and quercetin in the management of diabetic nephropathy and peripheral neuropathy. This may contribute to the development of more efficient and comprehensive treatment approaches for diabetes-associated complications.

Network Cluster Analysis of PPI and Phenotype Ontology for Type 1 Diabetes Mellitus

Background

Our knowledge of Type 1 Diabetes Mellitus (T1DM) etiology is incomplete; however, the pathogenesis of the disease includes T-cell-mediated destruction of β-cells.

Objective

The present study aimed to investigate the key gene pathways and co-expression networks in T1DM disease.

Material and Methods

TIDM-associated genes were identified from 13 databases, enrichment of pathways annotated with functional annotations, and analysis of protein-protein network interactions. Next, functional modules and transcription factor networks were constructed. The analysis of gene co-expression networks was conducted to discover associated pivotal modules.

Results

A total of 172 expressed genes and four variants (SNP) were filtered in the of T1DM disease; pathway enrichment analysis identified key pathways, such as inflammatory bowel disease, type I diabetes mellitus, cytokine-cytokine receptor interaction, Th17 cell differentiation, JAK-STAT signaling pathway, and graft-versus-host disease. A weighted correlation network analysis revealed one module that was strongly correlated with T1DM. Functional annotation revealed that the module was mainly enriched in pathways such as T cell activation, regulation of immune system process, and response to the organic substance. IRF2, IRF4, IRF8, and CDX2 were regulated in the module at a significant level.

Conclusion

The study identified IL-2 as a significant T1DM hotspot and highlighted the role of hub genes and transcription factors in the autoimmune disease, offering potentials for treatment and prevention.

Unraveling the Role of Tumor Necrosis Factor-Alpha in Diabetic Peripheral Neuropathy: A Systematic Review and Meta-Analysis

Diabetic peripheral neuropathy (DPN) is a prevalent and debilitating complication of diabetes mellitus, leading to sensory abnormalities, decreased balance, and increased risk of foot problems. Although tumor necrosis factor-alpha (TNF-α) has emerged as a potential factor in the pathogenesis of DPN, its role remains contested. This study intends to thoroughly analyze the association between TNF-α and DPN by combining data from various global studies. This systematic review and meta-analysis adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and included 23 articles investigating TNF-α levels in DPN patients for systematic review and 11 articles for meta-analysis. Data were extracted, and heterogeneity was examined. A random-effect model was chosen due to high heterogeneity. The major outcome measure across studies was serum TNF-α levels. The meta-analysis found a significant mean difference of 15.2464 (95% confidence interval = 4.4963; 25.9965) under the random-effect model due to the substantial heterogeneity (I2 = 98.1%) among included studies. The meta-analysis indicates a consistent elevation in TNF-α levels in individuals with DPN compared to those without neuropathy. This underlines the potential of TNF-α as a biomarker and contributor to diabetic neuropathy. Despite heterogeneity, the study's extensive scope and systematic approach enhance the trustworthiness and generalizability of the findings.

Cross-sectional study investigating the association between inflammatory biomarkers and neuropathy in adolescents with type 1 diabetes

OBJECTIVES

The aims of this study were to investigate circulating levels of inflammatory markers in adolescents with type 1 diabetes with and without different types of neuropathies and evaluate the association between inflammatory biomarkers, nerve function and clinical parameters.

DESIGN

Cross-sectional study.

SETTING

Hospitals and Steno Diabetes Center in Denmark.

PARTICIPANTS

Adolescents with more than 5 years of diabetes duration were investigated for large fibre, small fibre and autonomic neuropathy as a part of the T1DANES study. Blood samples from the participants were analysed for inflammatory biomarkers by Meso Scale Discovery multiplexing technology.

PRIMARY AND SECONDARY OUTCOME MEASURES

Inflammatory biomarkers and results of diagnostic nerve tests.

RESULTS

Fifty-six adolescents with type 1 diabetes and 23 healthy controls were included. The adolescents with diabetes had significantly higher interferon-gamma, tumour necrosis factor-alpha (TNF-a), interleukin (IL)-10 and soluble urokinase plasminogen activator receptor (suPAR) compared with healthy controls (p values<0.05). TNF-a was higher in the adolescents with large fibre neuropathy (LFN) (p=0.03) compared with those without LFN in the group with diabetes. A negative correlation was seen between TNF-a and conduction velocity in nervus tibialis (p=0.04), and higher TNF-a and IL-6 were associated with higher gastric motility index (TNF-a, p value=0.03; IL-6, p value=0.02). There were no significant associations between inflammatory markers and expressed symptoms, haemoglobin A1c, diabetes duration or body mass index standard derivation score (p values>0.05). The receiver operating characteristic (ROC) curves for the inflammatory markers suggested them as poor screening methods for all types of neuropathies with an area under the curve between 0.47 and 0.67.

CONCLUSION

Our results confirm increased low-grade inflammation in adolescents with type 1 diabetes. TNF-a was higher in adolescents with LFN and correlated negatively with nervus tibialis conduction velocity. The other inflammatory biomarkers fail to support differences in those with and without different types of diabetic neuropathies. However, TNF-a and IL-6 were positively correlated to gastric motility index.

Biomarkers in diabetic neuropathy

CONTEXT

The prevalence of diabetic neuropathy is drastically increasing in the world. To halt the progression of diabetic neuropathy, there is an unmet need to have potential biomarkers for the diagnosis and new drug discovery.

OBJECTIVE

To study various biomarkers involved in the pathogenesis of diabetic neuropathy.

METHODS

The literature was searched with the help of various scientific databases and resources like PubMed, ProQuest, Scopus, and Google scholar from the year 1976 to 2020.

RESULTS

Biomarkers of diabetic neuropathy are categorised as inflammatory biomarkers such as MCP-1, VEGF, TRPV1, NF-κB; oxidative biomarkers such as adiponectin, NFE2L2; enzyme biomarkers like NADPH, ceruloplasmin, HO-1, DPP-4, PARP α; miscellaneous biomarkers such as SIRT1, caveolin 1, MALAT1, and microRNA. All biomarkers have a significant role in the pathogenesis of diabetic neuropathy.

CONCLUSION

These biomarkers have a potential role in the progression of diabetic neuropathy and can be considered as potential targets for new drug discovery.

Systemic Cytokine Expression in Diabetes Is Associated with Prolonged Gastrointestinal Transit Times and Cardinal Gastroparesis Symptoms

Gastroenteropathy is a common complication in diabetes associated with damages to the enteric nervous system. Systemic low-grade inflammation facilitates neurotoxicity, and associations with peripheral and autonomic neuropathy have been reported. However, less is known of associations with gastroenteropathy. To explore the area cross-sectionally, we included individuals with diabetes (type 1: 56, type 2: 100) and 21 healthy controls. Serum levels of interleukin (IL)-6, IL-8, IL-10, tumour necrosis factor (TNF)-α, and interferon (IFN)-γ were measured by multiplex technology. Segmental gastrointestinal transit times were assessed by wireless motility capsule investigations. Symptoms of gastroparesis were rated on Gastroparesis Cardinal Symptom Index questionnaires. Compared to healthy, levels of TNF-α were decreased in type 1 diabetes and increased in type 2 diabetes, while colonic transit time was increased (all p < 0.05). In diabetes, associations between IL-8 and prolonged gastric emptying (odds ratio (OR) 1.07, p = 0.027) and between IL-10 and prolonged colonic transit (OR 29.99, p = 0.013) were seen. Inverse correlations between IL-6 and nausea/vomiting (rho = −0.19, p = 0.026) and bloating (rho = −0.29; p < 0.001) were found. These findings indicate a plausible interaction between inflammation and the enteric nervous system in diabetes, which raises the question of whether anti-inflammatory strategies could be applied in management of diabetic gastroenteropathy.

Immune System Acts on Orthodontic Tooth Movement: Cellular and Molecular Mechanisms

Orthodontic tooth movement (OTM) is a tissue remodeling process based on orthodontic force loading. Compressed periodontal tissues have a complicated aseptic inflammatory cascade, which are considered the initial factor of alveolar bone remodeling. Since skeletal and immune systems shared a wide variety of molecules, osteoimmunology has been generally accepted as an interdisciplinary field to investigate their interactions. Unsurprisingly, OTM is considered a good mirror of osteoimmunology since it involves immune reaction and bone remolding. In fact, besides bone remodeling, OTM involves cementum resorption, soft tissue remodeling, orthodontic pain, and relapse, all correlated with immune cells and/or immunologically active substance. The aim of this paper is to review the interaction of immune system with orthodontic tooth movement, which helps gain insights into mechanisms of OTM and search novel method to short treatment period and control complications.

Association of Diet-Related Systemic Inflammation with Periodontitis and Tooth Loss: The Interaction Effect of Diabetes

Diet is an important factor that can affect inflammatory processes. Diet-related systemic inflammation is closely linked to periodontitis and tooth loss. However, the role that systemic conditions play in influencing this association remains unclear. A cross-sectional analysis was conducted using the National Health and Nutrition Examination Survey (NHANES) from 2009 to 2014. Diet-related systemic inflammation was assessed by the Dietary Inflammatory Index (DII). Multivariate Cox regression models were used to investigate the association between DII and periodontal results, including total periodontitis, tooth loss, severe tooth loss, and the number of teeth lost. The interaction effects between DII and established covariates were tested. Higher DII scores, corresponding to a higher pro-inflammatory potential of the diet, were associated with an increased risk of periodontitis and tooth loss among the 10,096 eligible participants. There was an interaction between diabetes and DII on total periodontitis (p = 0.0136). No significant interaction effect was detected between DII and other established covariates. Participants who consumed an anti-inflammatory diet, and did not have diabetes, experienced the lowest risks of periodontitis and tooth loss. However, in the context of diabetes, the efficacy of such a diet may be weakened or even eliminated. Dietary interventions to manage oral health problems may need to take the individual's metabolic condition into account.

Blood biomarkers of peripheral neuropathy

Traditionally, neurophysiology is the primary diagnostic and prognostic biomarker in peripheral neuropathy clinical practice; however, it may lack responsiveness in the context of slowly progressive neuropathies and where there is significant axonal damage. The development of ultrasensitive platforms for measuring serum proteins at the lower limit of detection of traditional ELISA techniques has transformed the field of blood biomarkers of peripheral neuropathy. A variety of blood biomarkers have been identified from inflammatory cytokines and apokines in diabetic neuropathy through to neuron-specific proteins such as neurofilament light chain, Schwann cell-specific proteins such as TMPRSS5 and microRNAs in other acquired and hereditary neuropathies. In this article, we review blood biomarkers of disease activity for the common subtypes of peripheral neuropathy including inflammatory demyelinating neuropathies, vasculitic neuropathy, diabetic neuropathy, chemotherapy-induced neuropathy and Charcot-Marie-Tooth disease and related disorders including TTR amyloidosis.

Anti-Inflammatory and Antinociceptive Effects of Boesenbergia rotunda Polyphenol Extract in Diabetic Peripheral Neuropathic Rats

Introduction

Methods

Results

Conclusion

Elevated levels of interleukin-12/23p40 may serve as a potential indicator of dysfunctional heart rate variability in type 2 diabetes

Background

Systemic inflammatory processes plausibly contribute to the development of cardiovascular complications, causing increased morbidity and mortality in type 2 diabetes. Circulating inflammatory markers, i.e., interleukin (IL)-6 and tumour necrosis factor-α, are associated with neurocardiac measures. We examined a broad panel of various inflammatory and inflammation-related serum markers to obtain more detailed insight into the possible neuro-immune interaction between cardiovascular regulation and systemic level of inflammation.

Methods

Serum samples from 100 participants with type 2 diabetes were analysed. Heart rate variability, cardiovascular autonomic reflex tests, and cardiac vagal tone tests were performed based on electrocardiographic readings. Data regarding covariates (demographic-, diabetes-, and cardiovascular risk factors) were registered.

Results

Increased serum levels of IL-12/IL-23p40 (p  < 0.01) and intercellular adhesion molecule (ICAM)-1 (p  < 0.007) were associated with diminished heart rate variability measures. After all adjustments, the associations between IL-12/23p40, SDANN and VLF persisted (p  = 0.001). Additionally, serum levels of vascular endothelial growth factor (VEGF)-C were associated with response to standing (p  = 0.005).

Discussion

The few but robust associations between neurocardiac regulation and serum markers found in this study suggest systemic changes in proinflammatory, endothelial, and lymphatic function, which collectively impacts the systemic cardiovascular function. Our results warrant further exploration of IL-12/IL-23p40, ICAM-1, and VEGF-C as possible cardiovascular biomarkers in T2D that may support future decisions regarding treatment strategies for improved patient care.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12933-021-01437-w.

Diagnostic Tools, Biomarkers, and Treatments in Diabetic polyneuropathy and Cardiovascular Autonomic Neuropathy

The various manifestations of diabetic neuropathy, including distal symmetric sensorimotor polyneuropathy (DSPN) and cardiovascular autonomic neuropathy (CAN), are among the most prevalent chronic complications of diabetes. Major clinical complications of diabetic neuropathies, such as neuropathic pain, chronic foot ulcers, and orthostatic hypotension, are associated with considerable morbidity, increased mortality, and diminished quality of life. Despite the substantial individual and socioeconomic burden, the strategies to diagnose and treat diabetic neuropathies remain insufficient. This review provides an overview of the current clinical aspects and recent advances in exploring local and systemic biomarkers of both DSPN and CAN assessed in human studies (such as biomarkers of inflammation and oxidative stress) for better understanding of the underlying pathophysiology and for improving early detection. Current therapeutic options for DSPN are (I) causal treatment, including lifestyle modification, optimal glycemic control, and multifactorial risk intervention, (II) pharmacotherapy derived from pathogenetic concepts, and (III) analgesic treatment against neuropathic pain. Recent advances in each category are discussed, including non-pharmacological approaches, such as electrical stimulation. Finally, the current therapeutic options for cardiovascular autonomic complications are provided. These insights should contribute to a broader understanding of the various manifestations of diabetic neuropathies from both the research and clinical perspectives.

Systemic inflammatory biomarkers in painful diabetic neuropathy

OBJECTIVES

We conducted a systematic review of the literature with meta-analysis to determine whether painful diabetic neuropathy is associated with a specific inflammatory profile.

METHODS

The study is based on the PRISMA statement for systematic reviews. We performed a search of published studies up until January 2021 in MEDLINE and Web of Science based on heading and free text terms. The search strategy included the phrases: diabetic peripheral neuropathy, painful peripheral neuropathy individually and in combination with the terms: inflammation and inflammatory biomarkers. We screened titles and abstracts and performed data extraction. We also manually searched the article titles in the reference lists of key studies and reviews published in the last 20 years.

DATA EXTRACTION

Data extracted from the studies included study design, inclusion and exclusion criteria, sample type including serum and plasma, source of the sample including patients with peripheral diabetic neuropathy or patients with painful and painless neuropathy of any etiology. Blood concentrations of all measured cytokines were recorded. Whenever possible we calculated the effect size and confidence interval. Non-human studies were excluded from the meta-analysis.

RESULTS

Thirteen studies were included in this meta-analysis. The study design was cross-sectional, case control or cohort type studies. Specific inflammatory mediators are significantly higher in painful than in painless diabetic neuropathy as well as in painful neuropathies of any etiology. Markers of inflammation are also increased in those patients with diabetes mellitus, who suffer from peripheral neuropathy in comparison to patients with diabetes mellitus but no signs of peripheral neuropathy. A proinflammatory state may be the common denominator of pain and peripheral neuropathy in patients with diabetes mellitus but the inflammatory profiles seem to differ.

The effects of Bushen Yiqi Huoxue prescription and its disassembled prescriptions on a diabetic retinopathy model in Sprague Dawley rats

BACKGROUND

Diabetic retinopathy (DR) is one of the most serious complications in the late stages of diabetes, with a complex mechanism. As a complication affecting local lesions, few studies have compared differences of cytokine expression in the serum and retina. Owing to the specific value of traditional Chinese medicine (TCM) to complex diseases, TCM research has recently boomed in the prevention and treatment of diabetes. Bushen Yiqi Huoxue (BYH) prescription is a Chinese herbal compound that has been independently developed by our research group and has been proved to have a positive effect on DR; however, its specific mechanism and compatibility rule remain to be further explored.

OBJECTIVE

To construct a DR model of Sprague Dawley (SD) rats, simultaneously detect multiple factor expression in the serum and retina of rats, explore the effect of BYH prescription and its disassembled prescriptions on DR, and discuss the influence of various compatibility combinations.

METHODS

BYH prescription was disassembled into two new compatibilities in the absence of Rehmanniae Radix (Yiqi Huoxue prescription, YH prescription) or Ginseng Radix et Rhizoma (Bushen Huoxue prescription, BH prescription). Male SD rats were induced using streptozotocin + high-fat and high-sugar diet to establish DR models and were divided into groups, then the intragastric administration and sampling. The body weight and fasting blood glucose of rats were continuously recorded during feeding; pathophysiological status observation of the retina by haematoxylin and eosin (HE) staining; advanced glycation end products (AGEs) and haemoglobin A1c (HbA1c) level detection in the rat serum by enzyme-linked immunosorbent assay; and the Luminex technique was used to detect the ICAM-1, IL-1β, IL-6, TNF-α and vascular endothelial growth factor (VEGF) expression concentrations in the retinal tissue and serum.

RESULTS

The results of blood glucose, body weight and HE staining proved that the model was successfully constructed, and the three combinations could reduce the retinal injury in DR rats. Serum AGEs and HbA1c levels of the model group increased compared with the control group (CG). Compared with the DR model group, only AGEs decreased in the BYH group, while the AGEs and HbA1c levels were significantly inhibited in the YH and BH groups, showing a significant correlation between the expression of AGEs and HbA1c in the serum of DR rats. In the serum of rats, IL-1β, IL-6, TNF-α and VEGF concentrations in the DR model group increased, although no statistical difference was observed in the ICAM-1 data compared with the CG. Compared with the DR model group, the IL-1β, IL-6 and TNF-α expression decreased in the BYH group. Moreover, the IL-6 and TNF-α expression decreased in the YH group and only the IL-6 expression decreased in the BH group. In the retina tissue, the model group had higher ICAM-1, IL-1β, IL-6, TNF-α and VEGF levels than the CG. Compared with the DR model group, TNF-α in the BYH group rats decreased, and the ICAM-1, IL-6 and TNF-α concentrations decreased in the YH and BH groups. Furthermore, differences in the ICAM-1 and VEGF expression in the serum and retina existed.

CONCLUSION

BYH compound and its disassembled prescriptions could improve the DR model rats induced with streptozotocin + high-fat and high-sugar diet, respectively, by inhibiting chronic blood glucose, AGEs, or inflammation response. The expression level and location of each factor are different, confirming that the effect of TCM prescriptions is not the simple addition of each single drug or its chemical components, but the rationality of its internal compatibility combination. Further, ICAM-1 and VEGF have exactly different expression levels, suggesting more attention to be paid by other researchers or doctors in future studies.

Molecular Mechanisms and Functions of lncRNAs in the Inflammatory Reaction of Diabetes Mellitus

Diabetes is a chronic inflammatory state, and several studies have shown that the mechanisms of insulin resistance and abnormal islet β-cell function in diabetes are closely related to inflammatory reactions. Inflammation plays a critical role in diabetic complications. Long noncoding RNAs (lncRNAs), a new area of genomic research for gene regulation, have complex biological functions in various aspects of cellular biological activity. Recent studies have shown that lncRNAs are associated with the regulation of inflammatory responses in various ways, including at the epigenetic, transcriptional, and posttranscriptional levels. This paper presents a brief review of studies on the mechanisms of lncRNAs in diabetic inflammation. The purpose of this article is to determine the role of lncRNAs in the process of diabetic inflammation and to provide new strategies for the use of lncRNAs in the treatments for diabetic inflammation.

Circulating Inflammatory Markers Are Inversely Associated with Heart Rate Variability Measures in Type 1 Diabetes

Introduction

A neuroimmune communication exists, and compelling evidence suggests that diabetic neuropathy and systemic inflammation are linked. Our aims were (1) to investigate biomarkers of the ongoing inflammation processes including cytokines, adhesion molecules, and chemokines and (2) to associate the findings with cardiovascular autonomic neuropathy in type 1 diabetes by measuring heart rate variability and cardiac vagal tone.

Materials and Methods

We included 104 adults with type 1 diabetes. Heart rate variability, time domain, and frequency domains were calculated from a 24-hour Holter electrocardiogram, while cardiac vagal tone was determined from a 5-minute electrocardiogram. Cytokines (interleukin- (IL-) 1α, IL-4, IL-12p70, IL-13, IL-17, and tumor necrosis factor- (TNF-) α), adhesion molecules (E-selectin, P-selectin, and intercellular adhesion molecule- (ICAM-) 1), and chemokines (chemokine (C-C motif) ligand (CCL)2, CCL3, CCL4, and C-X-C motif chemokine (CXCL)10) were assessed using a Luminex multiplexing technology. Associations between concentrations of inflammatory biomarkers and continuous variables of heart rate variability and cardiac vagal tone were estimated using multivariable linear regression adjusting for age, sex, disease duration, and smoking.

Results

Participants with the presence of cardiovascular autonomic neuropathy had higher systemic levels of IL-1α, IL-4, CCL2, and E-selectin than those without cardiovascular autonomic neuropathy. IL-1α, IL-4, IL-12, TNF-α, and E-selectin were inversely associated with both sympathetic and parasympathetic heart rate variability measures (p > 0.01). Discussion. Our results show that several pro- and anti-inflammatory factors, believed to be involved in the progression of diabetic polyneuropathy, are associated with cardiovascular autonomic neuropathy, suggesting that these factors may also contribute to the pathogenesis of cardiovascular autonomic neuropathy. Our findings emphasize the importance of the neuroimmune regulatory system in the pathogenesis of neuropathy in type 1 diabetes.