Diabetic neuropathy is associated with activation of the TNF-alpha system in subjects with type 1 diabetes mellitus

The role of adiponectin and its receptor signaling in ocular inflammation-associated diseases

Ocular inflammation-associated diseases are leading causes of global visual impairment, with limited treatment options. Adiponectin, a hormone primarily secreted by adipose tissue, binds to its receptors, which are widely distributed throughout the body, exerting powerful physiological regulatory effects. The protective role of adiponectin in various inflammatory diseases has gained increasing attention in recent years. Previous studies have confirmed the presence of adiponectin and its receptors in the eyes. Furthermore, adiponectin and its analogs have shown potential as novel drugs for the treatment of inflammatory eye diseases. This article summarizes the evidence for the interplay between adiponectin and inflammatory eye diseases and provides new perspectives on the diagnostic and therapeutic possibilities of adiponectin.

How inflammation dictates diabetic peripheral neuropathy: An enlightening review

BACKGROUND

Diabetic peripheral neuropathy (DPN) constitutes a debilitating complication associated with diabetes. Although, the past decade has seen rapid developments in understanding the complex etiology of DPN, there are no approved therapies that can halt the development of DPN, or target the damaged nerve. Therefore, clarifying the pathogenesis of DPN and finding effective treatment are the crucial issues for the clinical management of DPN.

AIMS

This review is aiming to summary the current knowledge on the pathogenesis of DPN, especially the mechanism and application of inflammatory response.

METHODS

We systematically summarized the latest studies on the pathogenesis and therapeutic strategies of diabetic neuropathy in PubMed.

RESULTS

In this seminal review, the underappreciated role of immune activation in the progression of DPN is scrutinized. Novel insights into the inflammatory regulatory mechanisms of DPN have been unearthed, illuminating potential therapeutic strategies of notable clinical significance. Additionally, a nuanced examination of DPN's complex etiology, including aberrations in glycemic control and insulin signaling pathways, is presented. Crucially, an emphasis has been placed on translating these novel understandings into tangible clinical interventions to ameliorate patient outcomes.

CONCLUSIONS

This review is distinguished by synthesizing cutting-edge mechanisms linking inflammation to DPN and identifying innovative, inflammation-targeted therapeutic approaches.

Exploring the molecular mechanism of Xuebifang in the treatment of diabetic peripheral neuropathy based on bioinformatics and network pharmacology

Background

Xuebifang (XBF), a potent Chinese herbal formula, has been employed in managing diabetic peripheral neuropathy (DPN). Nevertheless, the precise mechanism of its action remains enigmatic.

Purpose

The primary objective of this investigation is to employ a bioinformatics-driven approach combined with network pharmacology to comprehensively explore the therapeutic mechanism of XBF in the context of DPN.

Study design and Methods

The active chemicals and their respective targets of XBF were sourced from the TCMSP and BATMAN databases. Differentially expressed genes (DEGs) related to DPN were obtained from the GEO database. The targets associated with DPN were compiled from the OMIM, GeneCards, and DrugBank databases. The analysis of GO, KEGG pathway enrichment, as well as immuno-infiltration analysis, was conducted using the R language. The investigation focused on the distribution of therapeutic targets of XBF within human organs or cells. Subsequently, molecular docking was employed to evaluate the interactions between potential targets and active compounds of XBF concerning the treatment of DPN.

Results

The study successfully identified a total of 122 active compounds and 272 targets associated with XBF. 5 core targets of XBF for DPN were discovered by building PPI network. According to GO and KEGG pathway enrichment analysis, the mechanisms of XBF for DPN could be related to inflammation, immune regulation, and pivotal signalling pathways such as the TNF, TLR, CLR, and NOD-like receptor signalling pathways. These findings were further supported by immune infiltration analysis and localization of immune organs and cells. Moreover, the molecular docking simulations demonstrated a strong binding affinity between the active chemicals and the carefully selected targets.

Conclusion

In summary, this study proposes a novel treatment model for XBF in DPN, and it also offers a new perspective for exploring the principles of traditional Chinese medicine (TCM) in the clinical management of DPN.

Determination of soluble tumor necrosis factor receptor II and secretory immunoglobulin A in saliva of patients with dementia

The prevalence of pain and dementia increases with age, affecting a significant percentage of the population due to aging. Both pathologies are connected through the inflammatory process, specifically through the tumor necrosis factor. The effect of this cytokine is mediated through the modulation of its TNFRI and TNFRII receptors, which are linked to the dementia process. In addition, immunoglobulins such as secretory immunoglobulin A (sIgA) have been recognized as one of the main biomarkers of pain in saliva. sTNFRII and sIgA levels were determined in saliva samples by ELISA from healthy people and patients with dementia in GDS stages 5-7. The concentrations of these markers were also correlated with the GDS stage and sex. We observed a significant decrease (*** p ≤ 0.001) in the levels of sTNFRII (pg/mL) and a significant increase (** p ≤ 0.01) in the levels of sIgA (ng/mL) in the saliva of patients with dementia compared to the healthy control group. We did not observe a correlation with the data of the biomarkers regarding the GDS stage and sex. The results obtained for sTNFRII are consistent with those obtained by other authors on brain tissue, who conclude that unopposed neuronal TNFRI signaling, when TNFRII is selectively downregulated, leads to a more severe course of AD pathogenesis. Regarding sIgA, the elevated values of sIgA may reflect the immune status of these patients. Therefore, these biomarkers can provide us with relevant information through a non-invasive method such as saliva analysis.

The Influence of Sildenafil-Metformin Combination on Hyperalgesia and Biochemical Markers in Diabetic Neuropathy in Mice

Background and objectives: Worldwide, approximately 500 million people suffer from diabetes and at least 50% of these people develop neuropathy. Currently, therapeutic strategies for reducing diabetic neuropathy (DN)-associated pain are limited and have several side effects. The purpose of the study was to evaluate the antihyperalgesic action of different sildenafil (phosphodiesterase-5 inhibitor) and metformin (antihyperglycemic agent) combinations in alloxan-induced DN. Methods: The study included 100 diabetic mice and 20 non-diabetic mice that were subjected to hot and cold stimulus tests. Furthermore, we determined the influence of this combination on TNF-α, IL-6 and nitrites levels in brain and liver tissues. Results: In both the hot-plate and tail withdrawal test, all sildenafil-metformin combinations administered in our study showed a significant increase in pain reaction latencies when compared to the diabetic control group. Furthermore, all combinations decreased blood glucose levels due to the hypoglycemic effect of metformin. Additionally, changes in nitrite levels and pro-inflammatory cytokines (TNF-α and IL-6) were observed after 14 days of treatment with different sildenafil-metformin combinations. Conclusions: The combination of these two substances increased the pain reaction latency of diabetic animals in a dose-dependent manner. Moreover, all sildenafil-metformin combinations significantly reduced the concentration of nitrites in the brain and liver, which are final products formed under the action of iNOS.

Impact of gut-peripheral nervous system axis on the development of diabetic neuropathy

Diabetes is a chronic metabolic disease caused by a reduction in the production and/or action of insulin, with consequent development of hyperglycemia. Diabetic patients, especially those who develop neuropathy, presented dysbiosis, with an increase in the proportion of pathogenic bacteria and a decrease in the butyrate-producing bacteria. Due to this dysbiosis, diabetic patients presented a weakness of the intestinal permeability barrier and high bacterial product translocation to the bloodstream, in parallel to a high circulating levels of pro-inflammatory cytokines such as TNF-α. In this context, we propose here that dysbiosis-induced increased systemic levels of bacterial products, like lipopolysaccharide (LPS), leads to an increase in the production of pro-inflammatory cytokines, including TNF-α, by Schwann cells and spinal cord of diabetics, being crucial for the development of neuropathy.

Identification of candidate biomarkers and pathways associated with type 1 diabetes mellitus using bioinformatics analysis

Type 1 diabetes mellitus (T1DM) is a metabolic disorder for which the underlying molecular mechanisms remain largely unclear. This investigation aimed to elucidate essential candidate genes and pathways in T1DM by integrated bioinformatics analysis. In this study, differentially expressed genes (DEGs) were analyzed using DESeq2 of R package from GSE162689 of the Gene Expression Omnibus (GEO). Gene ontology (GO) enrichment analysis, REACTOME pathway enrichment analysis, and construction and analysis of protein–protein interaction (PPI) network, modules, miRNA-hub gene regulatory network and TF-hub gene regulatory network, and validation of hub genes were performed. A total of 952 DEGs (477 up regulated and 475 down regulated genes) were identified in T1DM. GO and REACTOME enrichment result results showed that DEGs mainly enriched in multicellular organism development, detection of stimulus, diseases of signal transduction by growth factor receptors and second messengers, and olfactory signaling pathway. The top hub genes such as MYC, EGFR, LNX1, YBX1, HSP90AA1, ESR1, FN1, TK1, ANLN and SMAD9 were screened out as the critical genes among the DEGs from the PPI network, modules, miRNA-hub gene regulatory network and TF-hub gene regulatory network. Receiver operating characteristic curve (ROC) analysis confirmed that these genes were significantly associated with T1DM. In conclusion, the identified DEGs, particularly the hub genes, strengthen the understanding of the advancement and progression of T1DM, and certain genes might be used as candidate target molecules to diagnose, monitor and treat T1DM.

Redefining distal symmetrical polyneuropathy features in type 1 diabetes: a systematic review

Diabetic neuropathy is among the most frequent complications of both type 1 (T1DM) and type 2 diabetes (T2DM) and commonly manifests as a distal symmetrical polyneuropathy (DSPN). Despite evidence that T1DM- and T2DM-related DSPN are separate entities, most of our knowledge on diabetic DSPN derives from studies focused on type 2 diabetes. This systematic review provides an overview of current evidence on DSPN in T1DM, including its epidemiological, pathophysiological and clinical features, along with principal diagnostic tests findings. This review included 182 clinical and preclinical studies. The results indicate that DSPN is a less frequent complication in T1DM compared with T2DM and that distinctive pathophysiological mechanisms underlie T1DM-related DSPN development, with hyperglycemia as a major determinant. T1DM-related DSPN more frequently manifests with non-painful than painful symptoms, with lower neuropathic pain prevalence compared with T2DM-associated DSPN. The overt clinical picture seems characterized by a higher prevalence of large fiber-related clinical signs (e.g., ankle reflexes reduction and vibration hypoesthesia) and to a lesser extent small fiber damage (e.g., thermal or pinprick hypoesthesia). These findings as a whole suggest that large fibers impairment plays a dominant role in the clinical picture of symptomatic T1DM-related DSPN. Nevertheless, small fiber diagnostic testing shows high diagnostic accuracy in detecting early nerve damage and may be an appropriate diagnostic tool for disease monitoring and screening.

Exercise and Nutraceuticals: Eminent approach for Diabetic Neuropathy

Diabetic neuropathy is an incapacitating chronic pathological condition that encompasses a large group of diseases and manifestations of nerve damage. It affects approximately 50% of patients with diabetes mellitus. Autonomic, sensory, and motor neurons are affected. Disabilities are severe, along with poor recovery and diverse pathophysiology. Physical exercise and herbal-based therapies have the potential to decrease the disabilities associated with diabetic neuropathy. Aerobic exercises like walking, weight lifting, the use of nutraceuticals and herbal extracts are found to be effective. Literature from the public domain was studied emphasizing various beneficial effects of different exercises, use of herbal and nutraceuticals for their therapeutic action in diabetic neuropathy. Routine exercises and administration of herbal and nutraceuticals, either the extract of plant material containing the active phytoconstituent or isolated phytoconstituent at safe concentration, have been shown to have promising positive action in the treatment of diabetic neuropathy. Exercise has shown promising effects on vascular and neuronal health and has proven to be well effective in the treatment as well as prevention of diabetic neuropathy by various novel mechanisms, including herbal and nutraceuticals therapy is also beneficial for the condition. They primarily show the anti-oxidant effect, secretagogue, anti-inflammatory, analgesic, and neuroprotective action. Severe adverse events are rare with these therapies. The current review investigates the benefits of exercise and nutraceutical therapies in the treatment of diabetic neuropathy.

Therapeutic Potential of Polyphenols in the Management of Diabetic Neuropathy

Diabetic neuropathy (DN) is a common and serious diabetes-associated complication that primarily takes place because of neuronal dysfunction in patients with diabetes. Use of current therapeutic agents in DN treatment is quite challenging because of their severe adverse effects. Therefore, there is an increased need of identifying new safe and effective therapeutic agents. DN complications are associated with poor glycemic control and metabolic imbalances, primarily oxidative stress (OS) and inflammation. Various mediators and signaling pathways such as glutamate pathway, activation of channels, trophic factors, inflammation, OS, advanced glycation end products, and polyol pathway have a significant contribution to the progression and pathogenesis of DN. It has been indicated that polyphenols have the potential to affect DN pathogenesis and could be used as potential alternative therapy. Several polyphenols including kolaviron, resveratrol, naringenin, quercetin, kaempferol, and curcumin have been administered in patients with DN. Furthermore, chlorogenic acid can provide protection against glutamate neurotoxicity via its hydrolysate, caffeoyl acid group, and caffeic acid through regulating the entry of calcium into neurons. Epigallocatechin-3-gallate treatment can protect motor neurons by regulating the glutamate level. It has been demonstrated that these polyphenols can be promising in combating DN-associated damaging pathways. In this article, we have summarized DN-associated metabolic pathways and clinical manifestations. Finally, we have also focused on the roles of polyphenols in the treatment of DN.

Small Nerve Fiber Damage and Langerhans Cells in Type 1 and Type 2 Diabetes and LADA Measured by Corneal Confocal Microscopy

Purpose

Increased corneal and epidermal Langerhans cells (LCs) have been reported in patients with diabetic neuropathy. The aim of this study was to quantify the density of LCs in relation to corneal nerve morphology and the presence of diabetic neuropathy and to determine if this differed in patients with type 1 diabetes mellitus (T1DM), type 2 diabetes mellitus (T2DM), and latent autoimmune diabetes of adults (LADA).

Methods

Patients with T1DM (n = 25), T2DM (n = 36), or LADA (n = 23) and control subjects (n = 23) underwent detailed assessment of peripheral neuropathy and corneal confocal microscopy. Corneal nerve fiber density (CNFD), branch density (CNBD), length (CNFL) and total, immature and mature LC densities were quantified.

Results

Lower CNFD (P < 0.001), CNBD (P < 0.0001), and CNFL (P < 0.0001) and higher LC density (P = 0.03) were detected in patients with T1DM, T2DM, and LADA compared to controls. CNBD was inversely correlated with mature (r = –0.5; P = 0.008), immature (r = –0.4; P = 0.02) and total (r = –0.5; P = 0.01) LC density, and CNFL was inversely correlated with immature LC density (r = –0.4; P = 0.03) in patients with T1DM but not in patients with T2DM and LADA.

Conclusions

This study shows significant corneal nerve loss and an increase in LC density in patients with T1DM, T2DM, and LADA. Furthermore, increased LC density correlated with corneal nerve loss in patients with T1DM.

Aging and the immune response in diabetic peripheral neuropathy

A large proportion of older individuals with diabetes go on to develop diabetic peripheral neuropathy (DPN). DPN is associated with an increase in inflammatory cells within the peripheral nerve, activation of nuclear factor kappa-light-chain-enhancer of activated B cells and receptors for advanced glycation end products/advanced glycation end products pathways, aberrant cytokine expression, oxidative stress, ischemia, as well as pro-inflammatory changes in the bone marrow; all processes that may be exacerbated with age. We review the immunological features of DPN and discuss whether age-related changes in relevant immunological areas may contribute to age being a risk factor for DPN.

Pathophysiology of Gastroparesis Syndromes Includes Anatomic and Physiologic Abnormalities

BACKGROUND

Factors underlying gastroparesis are not well defined.

AIMS

We hypothesized that multiple systems may be involved in patients with gastroparesis symptoms and performed a comparative physiologic study.

METHODS

We studied 43 consecutive eligible patients with gastroparetic symptoms categorized by GI symptoms, metabolic status, illness quantification, and gastric physiology. Patients were evaluated by two methods in each of five core areas: inflammatory, autonomic, enteric, electrophysiologic, and hormonal with abnormalities examined by correlations.

RESULTS

Patients had similar GI symptoms regardless of baseline gastric emptying or diabetic/idiopathic status, and all patients demonstrated abnormalities in each of the 5 areas studied. Nearly all patients presented with elevated markers of serum TNFα (88%) and serum IL-6 (91%); elevated cutaneous electrogastrogram frequency (95%); and interstitial cells of Cajal count abnormalities (inner: 97%, outer: 100%). Measures of inflammation correlated with a number of autonomic, enteric anatomy, electrophysiologic and hormonal abnormalities.

CONCLUSIONS

We conclude that patients with the symptoms of gastroparesis have multiple abnormalities, when studied by traditional, as well as newer, diagnostic assessments. Inflammation appears to be a fundamental abnormality that affects other organ systems in symptomatic patients. Future work on gastroparetic syndromes and their treatment may benefit from a focus on the diffuse nature of their illness, diverse pathophysiologic mechanisms involved, especially the possible causes of underlying inflammation and disordered hormonal status.

TRAIL REGISTRY

This study is registered with Clinicaltrials.gov under study # NCT03178370 https://clinicaltrials.gov/ct2/show/NCT03178370 .

Serum Levels of Inflammatory Proteins Are Associated With Peripheral Neuropathy in a Cross-Sectional Type-1 Diabetes Cohort

Chronic low-grade inflammation is involved in the pathogenesis of type-1 diabetes (T1D) and its complications. In this cross-section study design, we investigated association between serum levels of soluble cytokine receptors with presence of peripheral neuropathy in 694 type-1 diabetes patients. Sex, age, blood pressure, smoking, alcohol intake, HbA1c and lipid profile, presence of DPN (peripheral and autonomic), retinopathy and nephropathy was obtained from patient’s chart. Measurement of soluble cytokine receptors, markers of systemic and vascular inflammation was done using multiplex immunoassays. Serum levels were elevated in in DPN patients, independent of gender, age and duration of diabetes. Crude odds ratios were significantly associated with presence of DPN for 15/22 proteins. The Odds ratio (OR) remained unchanged for sTNFRI (1.72, p=0.00001), sTNFRII (1.45, p=0.0027), sIL2Rα (1.40, p=0.0023), IGFBP6 (1.51, p=0.0032) and CRP (1.47, p=0.0046) after adjusting for confounding variables, HbA1C, hypertension and dyslipidemia. Further we showed risk of DPN is associated with increase in serum levels of sTNFRI (OR=11.2, p<10), sIL2Rα (8.69, p<10^-15), sNTFRII (4.8, p<10^-8) and MMP2 (4.5, p<10^-5). We combined the serum concentration using ridge regression, into a composite score, which can stratify the DPN patients into low, medium and high-risk groups. Our results here show activation of inflammatory pathway in DPN patients, and could be a potential clinical tool to identify T1D patients for therapeutic intervention of anti-inflammatory therapies.

An updated pharmacological insight of resveratrol in the treatment of diabetic nephropathy

As one of the most common complications of diabetes, nephropathy develops in approximately 40% of diabetic individuals. Although end stage kidney disease is known as one of the most consequences of diabetic nephropathy, the majority of diabetic individuals might die from cardiovascular diseases and infections before renal replacement treatment. Moreover, the routine medical treatments for diabetes hold undesirable side effects. The explosive prevalence of diabetes urges clinicians and scientists to investigate the complementary or alternative therapies. Phytochemicals are emerging as alternatives with a wide range of therapeutic effects on various pathologies, including diabetic kidney disease. Of those phytochemicals, resveratrol, a natural polyphenolic stilbene, has been found to exert a broad spectrum of health benefits via various signaling molecules. In particular, resveratrol has gained a great deal of attention because of its anti-oxidative, anti-inflammatory, anti-diabetic, anti-obesity, cardiovascular-protective, and anti-tumor properties. In the renal system, emerging evidence shows that resveratrol has already been used to ameliorate chronic or acute kidney injury. This review critically summarizes the current findings and molecular mechanisms of resveratrol in diabetic renal damage. In addition, we will discuss the adverse and inconsistent effects of resveratrol in diabetic nephropathy. Although there is increasing evidence that resveratrol affords great potential in diabetic nephropathy therapy, these results should be treated with caution before its clinical translation. In addition, the unfavorable pharmacokinetics and/or pharmacodynamics profiles, such as poor bioavailability, may limit its extensive clinical applications. It is clear that further research is needed to unravel these limitations and improve its efficacy against diabetic nephropathy. Increasing investigation of resveratrol in diabetic kidney disease will not only help us better understand its pharmacological actions, but also provide novel potential targets for therapeutic intervention.

Proinflammatory cytokines predict the incidence of diabetic peripheral neuropathy over 5 years in Chinese type 2 diabetes patients: A prospective cohort study

BACKGROUND

Inflammation has been implicated in the pathogenesis of diabetic peripheral neuropathy (DPN) as suggested in various cross-sectional studies. However, more convincing prospective studies in diabetes patients are scarce. Therefore, we aimed to evaluate whether proinflammatory cytokines could predict the incidence of DPN through a prospective study with a five-year follow-up.

METHODS

We followed up 315 patients with diabetes who did not have DPN, recruited from five community health centers in Shanghai in 2014, for an average of 5.06 years. Based on the integrity of blood samples, 106 patients were selected to obtain the proinflammatory cytokines. Plasma markers of proinflammatory cytokines at baseline included interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), vascular endothelial growth factor (VEGF), and intercellular adhesion molecule 1 (ICAM-1). Neuropathy was assessed by MSNI at baseline and during follow-up.

FINDINGS

Among the 106 chosen patients, 63 developed DPN after 5.06±1.14 years of follow-up. The baseline plasma levels of TNF-α, IL-6, and ICAM-1 were higher in the neuropathic group (p<0.05). In multivariate models, increased plasma levels of TNF-α (hazard ratio, HR: 8.74 [95% confidence interval, CI: 1.05-72.68]; p <0.05) and ICAM-1 (HR 23.74 [95% CI:1.47-383.81]; p<0.05) were both associated with incident DPN, after adjusting for known DPN risk factors.

INTERPRETATION

Increased plasma levels of proinflammatory factors, especially TNF-α and ICAM-1, predicted the incidence of DPN over 5 years in Chinese diabetes patients, but larger longitudinal studies are required for confirmation.

FUNDING

National Natural Science Foundation of China, Shanghai Talent Development Fund Program, Shanghai Shenkang Hospital Developing Center Clinical Scientific and Technological Innovation Program, Shanghai Science and Technology Committee Program, Shanghai General Hospital Program of Chinese traditional and Western medicine combination and Shanghai Municipal Commission of Health and Family Planning Clinical Research Project.

Tranilast attenuates neuropathic pain during type-2 diabetes by inhibiting hypoxia-induced pro-inflammatory cytokines in Zucker diabetic fatty rat model

BACKGROUND

The modulatory effect of tranilast on neuropathic pain in type-2 diabetes (T2DM) remains unclear.

METHODS

We monitored interleukin (IL)-1β, nuclear factor-κB (NF-κB) and tumour necrosis factor-α (TNF-α) levels during the progression of T2DM induced neuropathic pain in rats, and assessed the impact of tranilast treatment of increasing concentrations (0, 200 and 400 mg/kg/day via oral gavage in 1% NaHCO₃ delivered as 100 mg/kg twice a day) on the levels of cytokine production, as well as on the thermal hyperalgesia and mechanical allodynia.

RESULTS

The rats developed hyperglycaemia accompanied with elevated levels of NF-κB, IL-1β and TNF-α in the rostral ventromedial medulla at the age of 16 weeks. Tranilast administration dose dependently alleviated thermal hyperalgesia as well as mechanical allodynia, which was associated with its ability in inhibiting hypoxia-induced levels of NF-κB, IL-1β and TNF-α.

CONCLUSION

Tranilast plays crucial roles in modulating T2DM-related neuropathic pain, likely through inhibiting hypoxia.

Soluble Tumor Necrosis Factor Receptor Type 1 Levels Exhibit A Stronger Association With Renal Outcomes Than Traditional Risk Factors in Chinese Subjects With Type 2 Diabetes Mellitus

OBJECTIVE

Associations between albuminuria and renal outcomes are inconsistent in patients with type 2 diabetes (T2D). Soluble tumor necrosis factor receptor type 1 (sTNFR1) is involved in declined kidney function and poor renal outcomes but this has not been confirmed among Chinese T2D patients. This study aimed to examine the association of sTNFR1 and renal outcomes in a cohort of these patients.

METHODS

Two hundred and eighty-three Chinese T2D patients were enrolled in a prospective observational study which excluded individuals with estimated glomerular filtration rates (eGFR) <30 mL/min/1.73m2. Composite renal outcomes included either or both a >30% decline in eGFR and worsening albuminuria from consecutive tests of blood/urine during a 3.5-year follow-up.

RESULTS

Higher sTNFR1 levels were associated with impaired renal outcomes. sTNFR1 levels of ≥979 pg/mL yielded the most sensitivity and specific predictions of renal outcomes according to the receiver operating curve (area under the curve 0.68, P<.001; sensitivity 78.3%, specificity 48.9%). Renal events occurred more frequently in subjects with sTNFR1 ≥979 pg/mL than in others (sTNFR1 <979 pg/mL; 29% versus 10%; P<.001 by log-rank test). The association between sTNFR1 ≥979 pg/mL and renal outcomes remained significant after adjustment for relevant covariates (adjusted hazard ratio 2.43, 95% confidence interval 1.18 to 5.02; P = .01) and consistent across subgroups stratified by age, sex, blood pressure, eGFR, albuminuria, and the use of renin-angiotensin system inhibitors.

CONCLUSION

Increased sTNFR1 levels were associated with renal outcomes in Chinese T2D subjects, making sTNFR1 a potential biomarker in diabetic kidney disease.

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

OBJECTIVE

Distal symmetrical polyneuropathy (DSPN) is a severe common long-term complication of type 1 diabetes caused by impaired sensory-motor nerve function. As chronic low-grade inflammation may be involved in the pathogenesis of DSPN, we investigated the circulating levels of inflammatory markers in individuals with type 1 diabetes with and without DSPN. Furthermore, we determined to what extent these factors correlated with different peripheral sensory nerve functions.

DESIGN

Cross-sectional study.

PATIENTS

The study included 103 individuals with type 1 diabetes with (n = 50) and without DSPN (n = 53) as well as a cohort of healthy controls (n = 21).

MEASUREMENTS

Circulating levels of various inflammatory markers (cytokines, chemokines and soluble adhesion molecules) were determined in serum samples by Luminex multiplexing technology. Peripheral sensory nerve testing, for example vibration, tactile and thermal perception, was assessed by standardized procedures.

RESULTS

The cytokines IL-1α, IL-4, IL-12p70, IL-13, IL-17A and TNF-α; the chemokine MCP-1; and the adhesion molecule E-selectin were significantly increased in individuals with type 1 diabetes with DSPN compared to those without DSPN (P < .001). These observations were independent of age, sex, BMI, disease duration and blood pressure. Additionally, higher serum concentrations of cytokines and chemokines were associated with higher vibration and tactile perception thresholds, but not with heat tolerance threshold.

CONCLUSIONS

Individuals with type 1 diabetes and concomitant DSPN display higher serum levels of several inflammatory markers. These findings support that systemic low-grade inflammation may play a role in the pathogenesis of DSPN.

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.

Utility of Insulin Resistance in Estimating Cardiovascular Risk in Subjects with Type 1 Diabetes According to the Scores of the Steno Type 1 Risk Engine

BACKGROUND

We sought to assess the potential of insulin resistance (IR) for estimating cardiovascular disease (CVD) risk in adults with type 1 diabetes (T1DM) according to the scores of the Steno Type 1 Risk Engine (ST1RE).

METHODS

A total of 179 adults with T1DM (50.8% men, age 41.2 ± 13.1 years, duration of T1DM 16 (12-23) years) without established CVD were evaluated. IR was assessed by the estimation of insulin sensitivity (eIS) using two validated prediction equations: the estimated insulin sensitivity developed from the Pittsburgh Epidemiology of Diabetes Complications Study (eIS-EDC) and the estimated insulin sensitivity developed from Coronary Artery Calcification in T1DM Study (eIS-CACTI) ST1RE was used to estimate 10-year CVD risk and to classify subjects into three groups according to their risk: low (<10%; n = 105), moderate (10-20%; n = 53), and high (≥20%; n = 21).

RESULTS

Both eIS-EDC and eIS-CACTI correlated negatively with ST1RE scores (eIS-EDC: r = -0.636, p < 0.001; eIS-CACTI: r = -0.291, p < 0.001). The C-statistic for predicting moderate/high risk and high risk was 0.816 (95% confidence interval (CI): 0.754-0.878) and 0.843 (95% CI: 0.772-0.913), respectively, for the eIS-EDC equation, and was 0.686 (95% CI: 0.609-0.763) and 0.646 (95% CI: 0.513-0.778), respectively, for the eIS-CACTI equation. The eIS-EDC equation had a significantly higher C-statistic both for moderate-/high-risk (p = 0.001) and high-risk (p = 0.007) subjects. Two cut-off points of eIS-EDC were identified for detecting moderate/high risk (8.52 mg·kg^-1·min^-1; sensitivity 74% and specificity 76%) and high risk (8.08 mg·kg^-1·min^-1; sensitivity 65% and specificity 95%) with potential applicability in clinical practice.

CONCLUSIONS

eIS negatively correlates with the score of CVD risk in the ST1RE. Two cut-off points of eIS are reported with potential utility in clinical practice for detecting adults with T1DM with the highest CVD risk.

TNF-α mediated upregulation of NaV1.7 currents in rat dorsal root ganglion neurons is independent of CRMP2 SUMOylation

Clinical and preclinical studies have shown that patients with Diabetic Neuropathy Pain (DNP) present with increased tumor necrosis factor alpha (TNF-α) serum concentration, whereas studies with diabetic animals have shown that TNF-α induces an increase in Na_V1.7 sodium channel expression. This is expected to result in sensitization of nociceptor neuron terminals, and therefore the development of DNP. For further study of this mechanism, dissociated dorsal root ganglion (DRG) neurons were exposed to TNF-α for 6 h, at a concentration equivalent to that measured in STZ-induced diabetic rats that developed hyperalgesia. Tetrodotoxin sensitive (TTXs), resistant (TTXr) and total sodium current was studied in these DRG neurons. Total sodium current was also studied in DRG neurons expressing the collapsin response mediator protein 2 (CRMP2) SUMO-incompetent mutant protein (CRMP2-K374A), which causes a significant reduction in Na_V1.7 membrane cell expression levels. Our results show that TNF-α exposure increased the density of the total, TTXs and TTXr sodium current in DRG neurons. Furthermore, TNF-α shifted the steady state activation and inactivation curves of the total and TTXs sodium current. DRG neurons expressing the CRMP2-K374A mutant also exhibited total sodium current increases after exposure to TNF-α, indicating that these effects were independent of SUMOylation of CRMP2. In conclusion, TNF-α sensitizes DRG neurons via augmentation of whole cell sodium current. This may underlie the pronociceptive effects of TNF-α and suggests a molecular mechanism responsible for pain hypersensitivity in diabetic neuropathy patients.

Liraglutide treatment reduced interleukin-6 in adults with type 1 diabetes but did not improve established autonomic or polyneuropathy

AIMS

Type 1 diabetes can be complicated with neuropathy that involves immune-mediated and inflammatory pathways. Glucagon-like peptide-1 receptor agonists such as liraglutide, have shown anti-inflammatory properties, and thus we hypothesized that long-term treatment with liraglutide induced diminished inflammation and thus improved neuronal function.

METHODS

The study was a randomized, double-blinded, placebo-controlled trial of adults with type 1 diabetes and confirmed symmetrical polyneuropathy. They were randomly assigned (1:1) to receive either liraglutide or placebo. Titration was 6 weeks to 1.2-1.8 mg/d, continuing for 26 weeks. The primary endpoint was change in latency of early brain evoked potentials. Secondary endpoints were changes in proinflammatory cytokines, cortical evoked potential, autonomic function and peripheral neurophysiological testing.

RESULTS

Thirty-nine patients completed the study, of whom 19 received liraglutide. In comparison to placebo, liraglutide reduced interleukin-6 (-22.6%; 95% confidence interval [CI]: -38.1, -3.2; P = .025) with concomitant numerical reductions in other proinflammatory cytokines. However neuronal function was unaltered at the central, autonomic or peripheral level. Treatment was associated with -3.38 kg (95% CI: -5.29, -1.48; P < .001] weight loss and a decrease in urine albumin/creatinine ratio (-40.2%; 95% CI: -60.6, -9.5; P = .02).

CONCLUSION

Hitherto, diabetic neuropathy has no cure. Speculations can be raised whether mechanism targeted treatment, e.g. lowering the systemic level of proinflammatory cytokines may lead to prevention or treatment of the neuroinflammatory component in early stages of diabetic neuropathy. If ever successful, this would serve as an example of how fundamental mechanistic principles are translated into clinical practice similar to those applied in the cardiovascular and nephrological clinic.

Polyphenols for diabetes associated neuropathy: Pharmacological targets and clinical perspective

OBJECTIVES

Diabetic neuropathy (DNP) is a widespread and debilitating complication with complex pathophysiology that is caused by neuronal dysfunction in diabetic patients. Conventional therapeutics for DNP are quite challenging due to their serious adverse effects. Hence, there is a need to investigate novel effective and safe options. The novelty of the present study was to provide available therapeutic approaches, emerging molecular mechanisms, signaling pathways and future directions of DNP as well as polyphenols' effect, which accordingly, give new insights for paving the way for novel treatments in DNP.

EVIDENCE ACQUISITION

A comprehensive review was done in electronic databases including Medline, PubMed, Web of Science, Scopus, national database (Irandoc and SID), and related articles regarding metabolic pathways on the pathogenesis of DNP as well as the polyphenols' effect. The keywords "diabetic neuropathy" and "diabetes mellitus" in the title/abstract and "polyphenol" in the whole text were used. Data were collected from inception until May 2019.

RESULTS

DNP complications is mostly related to a poor glycemic control and metabolic imbalances mainly inflammation and oxidative stress. Several signaling and molecular pathways play key roles in the pathogenesis and progression of DNP. Among natural entities, polyphenols are suggested as multi-target alternatives affecting most of these pathogenesis mechanisms in DNP.

CONCLUSION

The findings revealed novel pathogenicity signaling pathways of DNP and affirmed the auspicious role of polyphenols to tackle these destructive pathways in order to prevent, manage, and treat various diseases. Graphical Abstract .

Trigonelline reduced diabetic nephropathy and insulin resistance in type 2 diabetic rats through peroxisome proliferator-activated receptor-γ

Trigonelline has been reported to serve an important role in cell cycle control, oxidative and ultraviolet stress and DNA methylation. In the present study, the effects of trigonelline were examined on type-2 diabetes mellitus (T2DM)-induced renal dysfunction, and its possible mechanism was investigated. Sprague-Dawley rats were fed with high-fat diet (HFD) for 4 weeks and intraperitoneally injected with 35 mg/kg of streptozotocin for 4 weeks. As a result, trigonelline increased body weight, inhibited the kidney weight/body weight ratio and blood glucose levels, and reduced the levels of blood urea nitrogen, creatinine and albumin in type 2 diabetic rats. In addition, trigonelline also reduced inflammation, oxidative stress and kidney cell apoptosis in T2DM rats. In terms of the molecular mechanisms involved, trigonelline induced the protein expression of peroxisome proliferator-activated receptor (PPAR)-γ and suppressed glucose transporter 4 but suppressed the protein expression of tumor necrosis factor-α and leptin in T2DM rats. The present results demonstrated that trigonelline reduced diabetic nephropathy and insulin resistance in T2DM rats through PPAR-γ.

Emerging Biomarkers, Tools, and Treatments for Diabetic Polyneuropathy

Diabetic neuropathy, with its major clinical sequels, notably neuropathic pain, foot ulcers, and autonomic dysfunction, is associated with substantial morbidity, increased risk of mortality, and reduced quality of life. Despite its major clinical impact, diabetic neuropathy remains underdiagnosed and undertreated. Moreover, the evidence supporting a benefit for causal treatment is weak at least in patients with type 2 diabetes, and current pharmacotherapy is largely limited to symptomatic treatment options. Thus, a better understanding of the underlying pathophysiology is mandatory for translation into new diagnostic and treatment approaches. Improved knowledge about pathogenic pathways implicated in the development of diabetic neuropathy could lead to novel diagnostic techniques that have the potential of improving the early detection of neuropathy in diabetes and prediabetes to eventually embark on new treatment strategies. In this review, we first provide an overview on the current clinical aspects and illustrate the pathogenetic concepts of (pre)diabetic neuropathy. We then describe the biomarkers emerging from these concepts and novel diagnostic tools and appraise their utility in the early detection and prediction of predominantly distal sensorimotor polyneuropathy. Finally, we discuss the evidence for and limitations of the current and novel therapy options with particular emphasis on lifestyle modification and pathogenesis-derived treatment approaches. Altogether, recent years have brought forth a multitude of emerging biomarkers reflecting different pathogenic pathways such as oxidative stress and inflammation and diagnostic tools for an early detection and prediction of (pre)diabetic neuropathy. Ultimately, these insights should culminate in improving our therapeutic armamentarium against this common and debilitating or even life-threatening condition.

TNF-α and sTNF-RII Are Associated with Pain Following Hip Fracture Surgery in Older Adults

Objective

To explore whether plasma inflammatory mediators on postoperative day 3 (POD3) are associated with pain scores in older adults after hip fracture surgery.

Design

Cross-sectional study.

Setting

Mount Sinai Hospital, New York, New York.

Subjects

Forty patients age 60 years or older who presented with acute hip fracture at Mount Sinai Hospital between November 2011 and April 2013.

Methods

Plasma levels of six inflammatory mediators of the nuclear factor kappa B pathway were measured using blood collected on POD3. Self-reported pain scores (i.e., pain with resting, walking, and transferring) were assessed at baseline (prefracture) and on POD3. Linear regression models using log-transformed data were performed to determine associations between inflammatory mediators and postoperative pain.

Results

Interleukin 18 (IL-18) was positively associated with POD3 resting pain score in the unadjusted model (β = 0.66, P = 0.03). Tumor necrosis factor α (TNF-α) and soluble TNF receptor II (sTNF-RII) were positively associated with POD3 resting pain score in the adjusted model (β = 0.99, P = 0.03, and β = 0.86, P = 0.04, respectively). Moreover, TNF-α was positively associated with POD3 walking pain score in the adjusted model (β = 1.59, P = 0.05). Pain with transferring was not associated with these inflammatory mediators.

Conclusions

These findings suggest that TNF-α and its receptors may influence pain following hip fracture. Further study of the TNF-α pathway may inform future clinical applications that monitor and treat pain in the vulnerable elderly who are unable to accurately report pain.

Targeting tumor necrosis factor in the brain relieves neuropathic pain

Neuropathic pain is a chronic syndrome caused by direct damage to or disease of the somatosensory nervous system. The lack of safe, adequate and sustained pain relief offered by present analgesic treatments is most alarming. While many treatment options are available to manage chronic pain, such as antidepressants, non-steroidal anti-inflammatory agents, opioids, and anticonvulsants, chronic neuropathic pain remains largely unmanaged. Compounding the dilemma of ineffective chronic pain treatments is the need to provide relief from suffering and yet not contribute to the scourge of drug abuse. A recent epidemic of addiction and accidental drug prescription overdoses parallel the increased use of opioid treatment, even though opioids are rarely an effective treatment of relieving chronic pain. To make matters worse, opioids may contribute to exacerbating pain, and side-effects such as cognitive impairment, nausea, constipation, development of tolerance, as well as their potential for addiction and overdose deaths exist. Clearly, there is an urgent need for alternative, non-opiate treatment of chronic pain. Innovative discoveries of pertinent brain mechanisms and functions are key to developing effective, safe treatments. Pioneering work has revealed the essential effects of the pleiotropic mediator tumor necrosis factor (TNF) on brain functioning. These studies establish that TNF inhibits norepinephrine release from hippocampal neurons, and show that excess TNF production within the hippocampus occurs during neuropathic pain, which mobilizes additional mechanisms that further inhibit norepinephrine release. Significantly, it has been verified that elevated levels of TNF in the brain are actually required for neuropathic pain development. Since TNF decreases norepinephrine release in the brain, enhanced TNF levels would prevent engagement of the norepinephrine descending inhibitory neuronal pain pathways. Increased levels of TNF in the brain are therefore critical to the development of neuropathic pain. Therefore, strategies that decrease this enhanced TNF expression in the brain will have superior analgesic efficacy. We propose this novel approach of targeting the pathologically high levels of brain TNF as an effective strategy in the treatment of the devastating syndrome of chronic pain.

A novel curcumin derivative for the treatment of diabetic neuropathy

Neuropathy is a common complication of long-term diabetes. Proposed mechanisms of neuronal damage caused by diabetes that are downstream of hyperglycemia and/or loss of insulin signaling include ischemic hypoxia, inflammation and loss of neurotrophic support. The curcumin derivative J147 is a potent neurogenic and neuroprotective drug candidate initially developed for the treatment of neurodegenerative conditions associated with aging that impacts many pathways implicated in the pathogenesis of diabetic neuropathy. Here, we demonstrate efficacy of J147 in ameliorating multiple indices of neuropathy in the streptozotocin-induced mouse model of type 1 diabetes. Diabetes was determined by blood glucose, HbA1c, and insulin levels and efficacy of J147 by behavioral, physiologic, biochemical, proteomic, and transcriptomic assays. Biological efficacy of systemic J147 treatment was confirmed by its capacity to decrease TNFα pathway activation and several other markers of neuroinflammation in the CNS. Chronic oral treatment with J147 protected the sciatic nerve from progressive diabetes-induced slowing of large myelinated fiber conduction velocity while single doses of J147 rapidly and transiently reversed established touch-evoked allodynia. Conduction slowing and allodynia are clinically relevant markers of early diabetic neuropathy and neuropathic pain, respectively. RNA expression profiling suggests that one of the pathways by which J147 imparts its protection against diabetic induced neuropathy may be through activation of the AMP kinase pathway. The diverse biological and therapeutic effects of J147 suggest it as an alternative to the polypharmaceutical approaches required to treat the multiple pathogenic mechanisms that contribute to diabetic neuropathy.

Berberine Ameliorates Diabetic Neuropathy: TRPV1 Modulation by PKC Pathway

In recent years, berberine has increasingly become a topic of research as a treatment for diabetes due to its repair function, which recovers damaged pancreatic β cells. However, it is the complications of diabetes that seriously affect patients' life quality and longevity, among which diabetic neuropathy and the consequent acute pain are the most common. In this study, we established STZ-induced diabetic models to observe whether berberine, a main constitute of Coptis chinensis Franch which has shown good hypoglycemic effects, could relieve diabetes-induced pain and explored its possible mechanism in rats and mice. Behavior assays showed increasing mechanical allodynia and thermal hyperalgesia thresholds by the Von Frey test and tail flick test during the treatment of berberine. It was found that the administration of berberine (20, 60 mg/kg; 30, 90 mg/kg) suppressed the expression of PKCε and TRPV1 which could be activated by hyperglycemia-induced inflammatory reaction. Our results also presented its capability to reduce the over expression of TNF-[Formula: see text] in diabetic rats and mice. TNF-[Formula: see text] is an inflammatory cytokine, which is closely related to diabetic peripheral neuropathy (DPN). Consequently, we supposed that berberine exerts its therapeutic effects in part by suppressing the inflammatory process and blocking the PKC pathway to inhibit TRPV1 activation, which damages neurons and causes diabetic pain.

Functional recovery upon human dental pulp stem cell transplantation in a diabetic neuropathy rat model

Diabetic neuropathy (DN) is among the most debilitating complications of diabetes. Here, we investigated the effects of human dental pulp stem cell (DPSC) transplantation in Streptozotocin (STZ)-induced neuropathic rats. Six weeks after STZ injection, DPSCs were transplanted through two routes, intravenous (IV) or intramuscular (IM), in single or two repeat doses. Two weeks after transplantation, a significant improvement in hyperalgesia, grip-strength, motor coordination and nerve conduction velocity was observed in comparison with controls. A rapid improvement in neuropathic symptoms was observed for a single dose of DPSC IV; however, repeat dose of DPSC IV did not bring about added improvement. A single dose of DPSC IM showed steady improvement, and further recovery continued upon repeat IM administration. DPSC single dose IV showed greater improvement than DPSC single dose IM, but IM transplantation brought about better improvement in body weight. A marked reduction in tumor necrosis factor (TNF) α and C-reactive protein (CRP) levels was observed in the blood plasma for all treated groups, as compared with controls. With respect to inflammatory cytokines, repeat dose of DPSC IM showed further improvement, suggesting that a repeat dose is required to maintain the improved inflammatory state. Gene expression of inflammatory markers in liver confirmed amelioration in inflammation. Arachidonic acid level was unaffected by IV DPSC transplantation but showed noticeable increase through IM administration of a repeat dose. These results suggest that DPSC transplantation through both routes and dosage was beneficial for the retrieval of neuropathic parameters of DN; transplantation via the IM route with repeat dose was the most effective.

Proinflammatory Cytokines Predict the Incidence and Progression of Distal Sensorimotor Polyneuropathy: KORA F4/FF4 Study

OBJECTIVE

Experimental and epidemiological studies have implicated inflammatory processes in the pathogenesis of distal sensorimotor polyneuropathy (DSPN), but prospective studies are lacking. We hypothesized that biomarkers of inflammation predict the development and progression of DSPN in a population-based cohort.

RESEARCH DESIGN AND METHODS

This study was based on participants aged 62-81 years from the Cooperative Health Research in the Region of Augsburg (KORA) F4/FF4 cohort, with a mean follow-up of 6.5 years. The predictive value of systemic levels of eight biomarkers of inflammation was assessed for incident DSPN in 133 incident case subjects and 397 individuals without incident DSPN, and for DSPN progression in 57 patients with prevalent DSPN at both time points.

RESULTS

Higher hs-CRP, interleukin (IL)-6, tumor necrosis factor (TNF)-α, IL-1 receptor antagonist (IL-1RA), and soluble intercellular adhesion molecule (sICAM-1) and lower adiponectin levels were associated with incident DSPN in age- and sex-adjusted analysis; IL-18 and omentin were not. IL-6 (odds ratio 1.31 [95% CI 1.00-1.71]) and TNF-α (odds ratio 1.31 [95% CI 1.03-1.67]) remained associated with incident DSPN after adjusting for known DSPN risk factors. The addition of both cytokines to a clinical risk model improved model fit and reclassification. sICAM-1 and IL-1RA were positively associated with progression of DSPN.

CONCLUSIONS

Systemic subclinical and vascular inflammation predicted both the onset and progression of DSPN over 6.5 years in an older general population. Thus modulation of inflammatory processes may be relevant to prevent and/or treat diabetic neuropathy.

Modeling Natural Killer Cell Targeted Immunotherapies

Animal models have extensively contributed to our understanding of human immunobiology and to uncover the underlying pathological mechanisms occurring in the development of diseases. However, mouse models do not reproduce the genetic and molecular complexity inherent in human disease conditions. Human immune system (HIS) mouse models that are susceptible to human pathogens and can recapitulate human hematopoiesis and tumor immunobiology provide one means to bridge the interspecies gap. Natural killer cells are the founding member of the innate lymphoid cell family. They exert a rapid and strong immune response against tumor and pathogen-infected cells. Their antitumor features have long been exploited for therapeutic purposes in the context of cancer. In this review, we detail the development of highly immunodeficient mouse strains and the models currently used in cancer research. We summarize the latest improvements in adoptive natural killer (NK) cell therapies and the development of novel NK cell sources. Finally, we discuss the advantages of HIS mice to study the interactions between human NK cells and human cancers and to develop new therapeutic strategies.

Pepino polyphenolic extract improved oxidative, inflammatory and glycative stress in the sciatic nerves of diabetic mice

The effect of pepino polyphenolic extract (PPE) on diabetic neuropathy was examined. Using HPLC/ESI-MS-MS analysis, PPE was demonstrated to contain coumaroyl and caffeoyl derivatives among polyphenols. PPE at 0.5 or 1% was supplied to diabetic mice for 12 weeks. The PPE intake at two doses significantly improved glycaemic control. These treatments reserved the glutathione (GSH) level, and decreased the thiobarbituric acid reactive substances (TBARS) level, reactive oxygen species (ROS), interleukin (IL)-6, tumour necrosis factor (TNF)-alpha, fructose, and glycation intermediates and precursors of advanced glycation end products (AGEs), such as methylglyoxal (MG) and N-(carboxymethyl)lysine (CML), in the sciatic nerves of diabetic mice. In a histological study of sciatic nerves, PPE had the effects in improving the nerves of diabetic mice, showing disorganization of the fascicle with numerous small myelinated fibers. The PPE intake at two doses retained the activity, and the protein and mRNA levels of glutathione peroxidase (GPX), and decreased protein expressions of aldose reductase (AR) and the receptor for the advanced glycation end product (RAGE) in sciatic nerves. These findings support that pepino polyphenolic extract could attenuate oxidative, inflammatory and glycative stress in diabetic peripheral nerves.

Anti-inflammatory effect of AMPK signaling pathway in rat model of diabetic neuropathy

Diabetic neuropathy (DN) is characterized as Hyperglycemia activates thdisturbed nerve conduction and progressive chronic pain. Inflammatory mediators, particularly cytokines, have a determinant role in the pathogenesis of neuropathic pain. The activity of adenosine monophosphate protein kinase (AMPK), an energy charge sensor with neuroprotective properties, is decreased in diabetes. It has been reported that activation of AMPK reduces the systemic inflammation through inhibition of cytokines. In this study, we aimed to investigate the probable protective effects of AMPK on DN in a rat of diabetes. DN was induced by injection of streptozotocin (65 mg/kg, i.p.). Motor nerve conduction velocities (MNCV) of the sciatic nerve, as an electrophysiological marker for peripheral nerve damage, were measured. Plasma levels of IL-6, TNF-α, CRP were assessed as relevant markers for inflammatory response. Also, the expression of phosphorylated AMPK (p-AMPK) and non-phosphorylated (non-p-AMPK) was evaluated by western blotting in the dorsal root ganglia. Histopathological assessment was performed to determine the extent of nerve damage in sciatic nerve. Our findings showed that activation of AMPK by metformin (300 mg/kg) significantly increased the MNCV and reduced the levels of inflammatory cytokines. In addition, we showed that administration of metformin increased the expression of p-AMPK as well as decline in the level of non p-AMPK. Our results demonstrated that co-administration of dorsomorphin with metformin reversed the beneficial effects of metformin. In conclusion, the results of this study demonstrated that the activation of AMPK signaling pathway in diabetic neuropathy might be associated with the anti-inflammatory response.

Activation of ephrinB-EphB receptor signalling in rat spinal cord contributes to maintenance of diabetic neuropathic pain

BACKGROUND

Diabetic neuropathic pain (DNP) is severe and intractable in clinic. The specific cellular and molecular mechanisms underlying DNP remain elusive and its treatment are limited. We investigated roles of EphB1 receptor in the development of DNP.

METHODS

Diabetic neuropathic pain was produced in male, adult, Sprague-Dawley rats by a single i.p. streptozotocin (STZ) or alloxan. Western blot analysis and immunohistochemistry were used to analyse expression of EphB1 receptor as well as the activation of the glial cells and the pro-inflammatory cytokines in the spinal cord. DNP manifested as mechanical allodynia, which was determined by measuring incidence of foot withdrawal in response to mechanical indentation of the hind paw by an electro von Frey filament.

RESULTS

Diabetic neuropathic pain and high blood glucose were exhibited simultaneously in around 70% of animals that received i.p. STZ or alloxan. Phosphorylation of EphB1, activation of the astrocytes and microglial cells, and level of tumour necrosis factor (TNF)-α and interleukin (IL)-1β in the spinal cord were significantly increased in rats with DNP. Spinal blocking EphB1 receptor activation in the late phase after STZ injection significantly suppressed the established mechanical allodynia as well as activation of the astrocytes and microglial cells and activity of TNF-α and IL-1β. However, spinal treatment of EphB1-Fc in the early phase after STZ injection did not prevent the induction of DNP.

CONCLUSIONS

EphB1 receptor activation in the spinal cord is critical to the maintenance, but not induction of diabetic pain. EphB1 receptor may be a potential target for relieving the established diabetic pain.

SIGNIFICANCE

Activation of EphB1 receptor in the spinal cord is critical to maintaining the established diabetic neuropathic pain, but not to diabetic pain induction. Spinal blocking EphB1 receptor activation suppresses ongoing diabetic neuropathic pain.

Effect of exercise on neurogenic inflammation in spinal cord of Type 1 diabetic rats

Neuropathy is a long-standing and hard to treat complication of diabetes that interferes almost 25-30% of diabetic patients and impacts the quality of life of the patients. Unforeseen side effects, dependency and addiction made the existing medical treatments comparatively ineffective. A number of studies indicate that moderate physical activity provides health-related advantages. However, existing data do not confirm whether regular physical activity would reduce the amount of inflammation in the nervous system of the subjects with Type 1 diabetes. This study reveals the significance of exercise to alleviate inflammation in the spinal cord of the nervous system and preserve sensory nerve function in animals with Type 1 diabetes after 6 weeks of exercise paradigm. Streptozotocin-diabetic animals were placed in motorized running wheels for sixty minutes per day, for five days a week for 6 weeks starting at one week after diabetes. Emerging evidence suggests that the increases in inflammatory mediators play an important role in the development of sensory neuropathy. This study shows that moderate exercise can reduce the release of a number of proinflammatory cytokines in the dorsal horn (DH) of spinal cord, subsequently delaying the development of neuropathy along with an increase in the anti-inflammatory mediator IL10 in the DH. In general, this study indicates that exercise may provide an alternative to the treatment for sensory neuropathy in Type 1 diabetic subjects via reducing the use of medication and providing an easier way to manage neuropathy.

Associations of serum anti-ganglioside antibodies and inflammatory markers in diabetic peripheral neuropathy

AIMS

To investigate the associations between inflammatory markers, serum anti-ganglioside antibodies (anti-GS-ab), serum plasminogen activator inhibitor-1 (PAI-1), tumor necrosis factor-α (TNF-α), C-reactive protein (CRP), and diabetic peripheral neuropathy (DPN).

METHODS

Study subjects were divided into three groups: normal group (N group) with 101 healthy individuals; diabetes mellitus without peripheral neuropathy group (DM group) with 87 patients; and DPN group with 178 cases. American Nicolet Viking IV electromyography was applied to detect nerve conduction velocity; enzyme linked immunosorbent assay was used to determine the levels of anti-GS-IgG-ab, PAI-1, and TNF-α; and immunoturbidimetry was employed to measure CRP levels.

RESULTS

Motor nerve conduction velocity and sensory nerve conduction velocity in the DNC group were significantly lower than in the N and DM groups (all P<0.05). Pairwise comparisons among diabetic peripheral neuropathy clinical (DPNC) levels were statistically significant (P<0.05), and the level of anti-GS-ab was positively correlated with DPNC. There were statistically significant differences in PAI-1, TNF-α, and CRP levels between the DPN group and DM and N groups (both P<0.05). Pairwise comparisons of PAI-1, TNF-α, and CRP levels among DPNC levels showed no statistical significance in volumes (P>0.05), and the concentration of anti-GS-IgM-ab was in significant positive correlated with PAI-1, TNF-α, and CRP levels.

CONCLUSION

Anti-GS-ab and inflammatory markers such as PAI-1, TNF-α, and CRP were associated with DPN and can be used as important indicators for the prediction and early diagnosis of DPN.

Adiponectin, markers of subclinical inflammation and nerve conduction in individuals with recently diagnosed type 1 and type 2 diabetes

OBJECTIVE

Subclinical inflammation has been implicated in the development of diabetic sensorimotor polyneuropathy (DSPN), but studies using electrophysiological assessment as outcomes are scarce. Therefore, we aimed to investigate associations of biomarkers reflecting different aspects of subclinical inflammation with motor and sensory nerve conduction velocity (NCV) in individuals with diabetes.

DESIGN AND METHODS

Motor and sensory NCV was assessed in individuals with recently diagnosed type 2 (n=352) or type 1 diabetes (n=161) from the baseline cohort of the observational German Diabetes Study. NCV sum scores were calculated for median, ulnar and peroneal motor as well as median, ulnar and sural sensory nerves. Associations between inflammation-related biomarkers, DSPN and NCV sum scores were estimated using multiple regression models.

RESULTS

In type 2 diabetes, high serum interleukin (IL)-6 was associated with the presence of DSPN and reduced motor NCV. Moreover, higher levels of high-molecular weight (HMW) adiponectin, total adiponectin and their ratio were associated with prevalent DSPN and both diminished motor and sensory NCV, whereas no consistent associations were observed for C-reactive protein, IL18, soluble intercellular adhesion molecule-1 and E-selectin. In type 1 diabetes, only HMW and total adiponectin showed positive associations with motor NCV.

CONCLUSIONS

Our results point to a link between IL6 and both DSPN and slowed motor NCV in recently diagnosed type 2 diabetes. The reverse associations between adiponectin and NCV in type 1 and type 2 diabetes are intriguing, and further studies should explore whether they may reflect differences in the pathogenesis of DSPN in both diabetes types.

Antagonism of the Prokineticin System Prevents and Reverses Allodynia and Inflammation in a Mouse Model of Diabetes

Neuropathic pain is a severe diabetes complication and its treatment is not satisfactory. It is associated with neuroinflammation-related events that participate in pain generation and chronicization. Prokineticins are a new family of chemokines that has emerged as critical players in immune system, inflammation and pain. We investigated the role of prokineticins and their receptors as modulators of neuropathic pain and inflammatory responses in experimental diabetes. In streptozotocin-induced-diabetes in mice, the time course expression of prokineticin and its receptors was evaluated in spinal cord and sciatic nerves, and correlated with mechanical allodynia. Spinal cord and sciatic nerve pro- and anti-inflammatory cytokines were measured as protein and mRNA, and spinal cord GluR subunits expression studied. The effect of preventive and therapeutic treatment with the prokineticin receptor antagonist PC1 on behavioural and biochemical parameters was evaluated. Peripheral immune activation was assessed measuring macrophage and T-helper cytokine production. An up-regulation of the Prokineticin system was present in spinal cord and nerves of diabetic mice, and correlated with allodynia. Therapeutic PC1 reversed allodynia while preventive treatment blocked its development. PC1 normalized prokineticin levels and prevented the up-regulation of GluN2B subunits in the spinal cord. The antagonist restored the pro-/anti-inflammatory cytokine balance altered in spinal cord and nerves and also reduced peripheral immune system activation in diabetic mice, decreasing macrophage proinflammatory cytokines and the T-helper 1 phenotype. The prokineticin system contributes to altered sensitivity in diabetic neuropathy and its inhibition blocked both allodynia and inflammatory events underlying disease.

The lung endothelin system: a potent therapeutic target with bosentan for the amelioration of lung alterations in a rat model of diabetes mellitus

PURPOSE

The aim of this study is to show the effect of a new mechanism on endothelin (ET) receptors in the physiopathology of diabetes-related pulmonary injury. We tested the hypothesis that dual ET-1 receptor antagonism via bosentan can reverse diabetes-induced lung injury.

METHODS

The rats (24 male) were separated into four groups: group 1 (HEALTHY): Control group; group 2 (DM): Streptozotocin 60 mg/kg (i.p.); group 3 (DM + BOS-1): Diabetes + bosentan 50 mg/kg per-os; group 4 (DM + BOS-2): Diabetes + bosentan 100 mg/kg per-os. The bosentan treatment was initiated immediately after the onset of STZ-induced diabetes and continued for 6 weeks.

RESULTS

In the treatment group, SOD activity was significantly increased, although GSH and MDA levels and TNF-α and TGF-β gene expression were decreased. Bosentan 50 mg/kg and bosentan 100 mg/kg showed a significantly down-regulatory effect on ET-1, ET-A, and ET-B mRNA expression.

CONCLUSIONS

In conclusion, increased endothelin levels in the lung associated with diabetes may be one cause of endothelial dysfunction, cytokine increase, and oxidant/antioxidant imbalance in the pathogenesis of complications that may develop during diabetes. With its multiple effects, bosentan therapy may be an effective option against complications that may develop in association with diabetes.

Dietary fish oil inhibits mechanical allodynia and thermal hyperalgesia in diabetic rats by blocking nuclear factor-κB-mediated inflammatory pathways

One of the most common complications of early-onset diabetes mellitus is peripheral diabetic neuropathy, which is manifested either by loss of nociception or by allodynia and hyperalgesia. Diabetes mellitus is a common metabolic disease in human beings with characteristic symptoms of hyperglycemia, chronic inflammation and insulin resistance. Dietary fatty acids, especially polyunsaturated fatty acids, have been shown anti-inflammatory role in various experimental conditions. The present study investigated the effects of fish oil supplementation on the inflammation in the dorsal root ganglion (DRG) of streptozotocin (STZ)-induced diabetes rats. The effects of diabetes and fish oil treatment on the allodynia and hyperalgesia were also evaluated. Dietary fish oil effectively attenuated both allodynia and hyperalgesia induce by STZ injection. Along with the behavioral findings, DRG from fish oil-treated diabetic rats displayed a decrease in inflammatory cytokines and the expression of nuclear factor-κB (NF-κB) compared with untreated diabetic rats. Fish oil supplementation also increased the phosphorylation of AKT in DRG of diabetic rats. These results suggested that dietary fish oil-inhibited allodynia and hyperalgesia in diabetic rats may stem from its anti-inflammatory potential by regulating NF-κB and AKT. Fish oil might be useful as an adjuvant therapy for the prevention and treatment of diabetic complications.

Moderate exercise training attenuates inflammatory mediators in DRG of Type 1 diabetic rats

Painful neuropathy is a long-term and difficult to treat complication of diabetes that affects 25% of diabetic patients and interferes with their quality of life. Unfortunately, available medical treatments are relatively ineffective due to dependency and addiction. Emerging research indicates that moderate-to-vigorous physical activity provides health-related benefits. However, adequate data is not available to determine whether regular exercise would prevent or delay the development of painful neuropathy in subjects with Type 1 diabetes. This study demonstrates the significance of moderate exercise in the amelioration of pain in animals with Type 1 diabetes after 6weeks of exercise paradigm. After initial acclimatization, streptozotocin-diabetic animals were placed in motorized running wheels for 60minperday, for five days a week for 6weeks starting at one week after diabetes. A growing body of evidence suggests that the release of proinflammatory cytokines plays an important role in the development and persistence of pain. This study demonstrates that moderate exercise increases the expression of inhibitory neurotransmitter enkephalin and also reduces the presence of a number of proinflammatory cytokines in the dorsal root ganglia (DRG), subsequently impeding the development of neuropathy along with a decrease in the voltage gated ion channels in the DRG. Overall, the study suggests that exercise may provide an alternate route of treatment of painful neuropathy in Type 1 diabetic subjects by decreasing the use of pain medications, thereby providing a more useful and efficient way for pain management.

High levels of soluble tumor necrosis factor receptors 1 and 2 and their association with mortality in patients undergoing hemodialysis

OBJECTIVE

Circulating soluble tumor necrosis factor receptors 1 and 2 (sTNFR1 and sTNFR2) are associated with chronic kidney disease (CKD) progression in patients with CKD or diabetes, and with higher mortality. However, data in patients with end-stage renal disease are scarce. Therefore, we analyzed serum levels of sTNFR1 and sTNFR2 and investigated their association with inflammatory markers and mortality in dialysis patients.

RESEARCH DESIGN AND METHODS

This was a longitudinal cohort study of 207 prevalent patients (median age 66 years, 56% men) undergoing hemodialysis in Stockholm, Sweden. Demographics, clinical characteristics, including comorbidities and laboratory data, were obtained at baseline, together with prospective follow-up for mortality.

RESULTS

The median sTNFR1 and sTNFR2 levels were 17,680 ng/l [95% confidence interval (CI) 17,023-18,337] and 24,450 ng/l (95% CI 23,721-25,179), respectively. During a follow-up of 31 months (interquartile range, 21-38), 77 patients died. There was no association between the levels of sTNFRs and mortality in Cox regression models, and no consistent trend towards higher or lower mortality was seen in Laplace regression models. sTNFR1 and sTNFR2 levels were highly associated with other inflammatory markers including interleukin-6, pentraxin 3 and TNF-α.

CONCLUSIONS

Prevalent hemodialysis patients have several-fold higher levels of sTNFRs compared to previous studies in CKD stage 4 patients. As no consistent association between TNFR and mortality was observed, clinical implications of measuring these receptors to predict outcome end-stage renal disease patients provide limited results.

Low serum adiponectin levels in children and adolescents with diabetic retinopathy

OBJECTIVE

The aim of this study was to elucidate the role of adiponectin, leptin, TNF-α and IL-6 on the early detection of the microvascular complications of type I diabetes.

MATERIALS AND METHODS

A total of 88 children were included in the study. There were 60 type I diabetic patients and 28 healthy control children.

RESULTS

The gender, age, weight, height, BMI and puberty status characteristics were similar in the patient and control groups (p>0.05). The serum leptin, TNF-α and IL-6 levels were similar between the patient and control groups (p>0.05) and the only difference was in the serum adiponectin level which was higher in the patient group (p:0.042). We also found no association between the adiponectin, leptin, TNF-α and IL-6 levels and diabetes duration (p>0.05). Leptin was high in the pubertal period (p:0.016), while adiponectin TNF-α and IL-6 levels were similar in the prepubertal and pubertal periods (p>0.05). The serum leptin level was high in microalbuminuria patients (p<0.041). The serum adiponectin, TNF-α, and IL-6 levels were not different in patients with and without microalbuminuria (p>0.05). The serum adiponectin level was lower in diabetic retinopathy patients (p:0.003), while the serum leptin level was higher (p:0.003). The TNF-α and IL-6 levels were similar in patients with and without retinopathy (p>0.05).

CONCLUSION

We found increased serum adinopectin levels in children and adolescents with type I diabetes mellitus and low levels in diabetic retinopathy patients. Patients with low serum adiponectin levels and high leptin levels should be more closely monitored for chronic complication development and better metabolic control should be aimed for.

The Association between Serum Cytokines and Damage to Large and Small Nerve Fibers in Diabetic Peripheral Neuropathy

Diabetic peripheral neuropathy (DPN) is a frequent complication of type 2 diabetes mellitus (DM) and may involve small and large peripheral nerve fibers. Recent evidence suggests a role of cytokines in DPN. The paper is aimed at exploring whether the serum concentration of cytokines is associated with small and large nerve fiber function and with neuropathic pain (NP). We recruited a group of 32 type 2 DM patients who underwent serum cytokines (TNF-α, IL-2, IL-4, IL-6, and IL-10) dosage as well as electrodiagnostic and quantitative sensory testing (QST) assessment to explore damage to large and small nerve fibers. Raised serum levels of IL-6 and IL-10 correlated with markers of large nerve fiber sensory and motor axonal damage. Raised IL-10 serum level was associated with signs of motor nerve demyelination. No differences were found in pain characteristics and electrodiagnostic and QST markers of small nerve fiber function in relation to cytokines serum levels. IL-6 and IL-10 serum levels were associated with large nerve fiber damage but not to small fibers function or NP. IL-6 and IL-10 cytokines might play a role in the pathogenesis of nerve fiber damage or represent a compensatory or neuroprotective mechanism.