Protective effects of cyclooxygenase-2 gene inactivation against peripheral nerve dysfunction and intraepidermal nerve fiber loss in experimental diabetes

Correlates of metabolic syndrome in people with chronic spinal cord injury

PURPOSE

We aimed at identifying clinical risk factors or early markers of metabolic syndrome (MetS) in people with spinal cord injury (SCI) that would facilitate a timely diagnosis and implementation of preventive/therapeutic strategies.

METHODS

One hundred sixty-eight individuals with chronic (> 1 year) SCI underwent clinical and biochemical evaluations. MetS was diagnosed according to modified criteria of the International Diabetes Federation validated in people with SCI. Wilcoxon rank-sum test and χ2 test were used to compare variables between groups with and without MetS. Multiple logistic regression analysis was performed to reveal independent associations with MetS among variables selected by univariate linear regression analyses.

RESULTS

MetS was diagnosed in 56 of 132 men (42.4%) and 17 of 36 women (47.2%). At univariate regression analyses, putative predictors of MetS were an older age, a higher number of comorbidities, a lower insulin-sensitivity, the presence and intensity of pain, a shorter injury duration, a poorer leisure time physical activity (LTPA) and an incomplete motor injury. At the multiple logistic regression analysis, a significant independent association with MetS only persisted for a poorer LTPA in hours/week (OR: 0.880, 95% CI 0.770, 0.990) and more severe pain symptoms as assessed by the numeral rating scale (OR: 1.353, 95% CI 1.085, 1.793).

CONCLUSION

In people with chronic SCI, intense pain symptoms and poor LTPA may indicate a high likelihood of MetS, regardless of age, SCI duration, motor disability degree, insulin-sensitivity and comorbidities.

Recent Advances in Biomolecular Patho-Mechanistic Pathways behind the Development and Progression of Diabetic Neuropathy

Diabetic neuropathy (DN) is a neurodegenerative disorder that is primarily characterized by distal sensory loss, reduced mobility, and foot ulcers that may potentially lead to amputation. The multifaceted etiology of DN is linked to a range of inflammatory, vascular, metabolic, and other neurodegenerative factors. Chronic inflammation, endothelial dysfunction, and oxidative stress are the three basic biological changes that contribute to the development of DN. Although our understanding of the intricacies of DN has advanced significantly over the past decade, the distinctive mechanisms underlying the condition are still poorly understood, which may be the reason behind the lack of an effective treatment and cure for DN. The present study delivers a comprehensive understanding and highlights the potential role of the several pathways and molecular mechanisms underlying the etiopathogenesis of DN. Moreover, Schwann cells and satellite glial cells, as integral factors in the pathogenesis of DN, have been enlightened. This work will motivate allied research disciplines to gain a better understanding and analysis of the current state of the biomolecular mechanisms behind the pathogenesis of DN, which will be essential to effectively address every facet of DN, from prevention to treatment.

Association of serum omentin levels with microvascular complications of type 2 diabetes mellitus: a systematic review and meta-analysis

Background and aims

Type 2 diabetes mellitus (T2DM) is a chronic condition associated with various microvascular complications, including neuropathy, retinopathy, and nephropathy. Recent studies have suggested a potential association between serum omentin levels and the risk of developing microvascular complications in patients with T2DM. However, the existing evidence remains inconclusive. Therefore, we conducted a systematic review and meta-analysis to examine the association between serum omentin levels and microvascular complications in T2DM patients.

Methods

A comprehensive search was conducted in PubMed, Scopus, and Google Scholar databases to retrieve relevant articles published up to May 2023. Observational studies investigating omentin levels association with microvascular complications in T2DM patients were included. Data was extracted and hence analyzed.

Results

A total of seven cross-sectional articles met the inclusion criteria, with a total population of 1587 participants. The meta-analysis revealed a significant association between serum omentin levels and microvascular complications in patients with T2DM. Serum omentin levels were lower in patients with microvascular complications than in those without complications (Mean difference, 95% confidence interval: -1.31 [-2.50, -0.13], I2 = 99.62%).

Conclusion

This systematic review and meta-analysis provides evidence supporting an association between serum omentin levels and microvascular complications in patients with T2DM. The findings suggest that Omentin may be lower in T2DM patients with microvascular complications. Further research is warranted to elucidate the underlying mechanisms and explore the clinical implications of these findings.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40200-023-01359-2.

Novel strategy: Identifying new markers for demyelination in diabetic distal symmetrical polyneuropathy

Objective

To develop a novel strategy for identifying acquired demyelination in diabetic distal symmetrical polyneuropathy (DSP).

Background

Motor nerve conduction velocity (CV) slowing in diabetic DSP exceeds expectations for pure axonal loss thus implicating superimposed acquired demyelination.

Methods

After establishing demyelination confidence intervals by regression analysis of nerve conduction data from chronic inflammatory demyelinating polyneuropathy (CIDP), we prospectively studied CV slowing in 90 diabetic DSP patients with and without at least one motor nerve exhibiting CV slowing (groups A and B) into the demyelination range by American Academy of Neurology (AAN) criteria respectively and 95 amyotrophic lateral sclerosis (ALS) patients. Simultaneously, secretory phospholipase A2 (sPLA2) activity was assessed in both diabetic groups and 46 healthy controls.

Results

No ALS patient exhibited CV slowing in more than two motor nerves based on AAN criteria or the confidence intervals. Group A demonstrated a significantly higher percentage of patients as compared to group B fulfilling the above criteria, with an additional criterion of at least one motor nerve exhibiting CV slowing in the demyelinating range and a corresponding F response in the demyelinating range by AAN criteria (70.3 % vs. 1.9 %; p < 0.0001). Urine sPLA2 activity was increased significantly in diabetic groups as compared to healthy controls (942.9 ± 978.0 vs. 591.6 ± 390.2 pmol/min/ml, p < 0.05), and in group A compared to Group B (1328.3 ± 1274.2 vs. 673.8 ± 576.9 pmol/min/ml, p < 0.01). More patients with elevated sPLA2 activity and more than 2 motor nerves with CV slowing in the AAN or the confidence intervals were identified in group A as compared to group B (35.1 % vs. 5.7 %, p < 0.001). Furthermore, 13.5 % of patients in diabetic DSP Group A, and no patients in diabetic DSP Group B, fulfilled an additional criterion of more than one motor nerve with CV slowing into the demyelinating range with its corresponding F response into the demyelinating range by AAN criteria.

Conclusion

A combination of regression analysis of electrodiagnostic data and a urine biological marker of systemic inflammation identifies a subgroup of diabetic DSP with superimposed acquired demyelination that may respond favorably to immunomodulatory therapy.

Non-pharmacological interventions for diabetic peripheral neuropathy: Are we winning the battle?

Despite the advent of relatively reliable modalities of diagnosing diabetic peripheral neuropathy (DPN), such as nerve conduction studies, there is still a knowledge gap about the pathophysiology, and thus limited available interventions for symptom control and curtailing disease progression. The pharmacologic aspect of management is mainly centred on pain control, however, there are several important aspects of DPN such as loss of vibration sense, pressure sense, and proprioception which are associated with risks to lower limb health, which pharmacotherapy does not address. Furthermore, published evidence suggests non-pharmacologic interventions such as glycaemic control through dietary modification and exercise need to be combined with other measures such as psychotherapy, to reach a desired, however modest effect. Acupuncture is emerging as an important treatment modality for several chronic medical conditions including neuropathic and other pain syndromes. In their study published in the World Journal of Diabetes on the potential of acupuncture to reduce DPN symptoms and enhance nerve conduction parameters, Hoerder et al have been able to demonstrate that acupuncture improves sensory function and that this effect is likely sustained two months after treatment cessation. Although previous studies also support these findings, larger multi-center randomized control trials including a sham-controlled arm accounting for a placebo effect are required. Overall, given the satisfactory safety profile and the positive results found in these studies, it is likely that acupuncture may become an important aspect of the repertoire of effective DPN management.

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.

Evaluation of subclinical left ventricular myocardial systolic dysfunction in type 2 diabetes mellitus patients with and without diabetes peripheral neuropathy by global myocardial work

AIMS

Speckle-tracking echocardiography can non-invasively estimate myocardial work (MW) to evaluate left ventricular (LV) myocardial systolic function. The present study evaluated whether MW may detect subclinical LV myocardial systolic dysfunction in type 2 diabetes mellitus (T2DM) patients with and without diabetes peripheral neuropathy (DPN).

METHODS

A total of 127 T2DM patients were included in the present study, including 67 T2DM patients with DPN. In addition, 73 sex- and age- matched healthy individuals served as normal controls. The global myocardial work index (GWI), global constructive work (GCW), global waste work (GWW), global positive work (GPW), global negative work (GNW), global work efficiency (GWE) and GCW/GWW were measured and analysed. Furthermore, the differences in MW parameters among normal controls, T2DM patients, and T2DM patients with DPN were analysed. Multiple regression models were built to explore for the independent influencing factors of GWI and GPW values in T2DM patients with DPN. Receiver operating characteristic curve analysis was performed to evaluate the sensitivity and specificity of MW in evaluating subclinical LV myocardial systolic dysfunction in T2DM patients with DPN.

RESULTS

The GWI, GCW and GPW of T2DM patients with DPN were significantly decreased compared with those of T2DM patients and normal controls (P < 0.001) and showed a significant decreasing trend overall (P trend < 0.001). GWE and GCW/GWW were significantly decreased in T2DM patients with DPN compared with normal controls (P < 0.05). Although GWW was not significantly different among the three groups, it showed an increasing trend (Ptrend = 0.033). High-density lipoprotein cholesterol (HDL-C) levels were independent influencing factor for decreased GWI (β = 0.21, P = 0.031) and GPW (β = 0.19, P = 0.043) values in T2DM patients with DPN. The combination of the GWI, GCW, GWE, GPW and GCW /GWW had good sensitivity (62.69%) and specificity (89.04%) when evaluating subclinical LV myocardial systolic dysfunction in T2DM patients with DPN.

CONCLUSIONS

Non-invasive evaluation of LV myocardial work can detect subclinical LV myocardial systolic dysfunction in T2DM patients with and without DPN. DPN has additive deleterious effects on LV myocardial systolic function in T2DM patients. The reduction of HDL-C levels may indicate the occurrence of subclinical LV myocardial systolic dysfunction in T2DM patients with DPN.

Residual risk of cardiovascular complications in statin-using patients with type 2 diabetes: the Taiwan Diabetes Registry Study

BACKGROUND

The residual risks of atherosclerotic cardiovascular disease in statin-treated patients with diabetes remain unclear. This study was conducted to identify factors associated with these residual risks in patients with no prior vascular event.

METHODS

Data on 683 statin-using patients with type 2 diabetes mellitus (T2DM) from the Taiwan Diabetes Registry were used in this study. Patients aged < 25 or > 65 years at the time of diabetes diagnosis and those with diabetes durations ≥ 20 years were excluded. The United Kingdom Prospective Diabetes Study risk engine (version 2.01; https://www.dtu.ox.ac.uk/riskengine/ ) was used to calculate 10-year residual nonfatal and fatal coronary heart disease (CHD) and stroke risks. Associations of these risks with physical and biochemical variables, including medication use and comorbidity, were examined.

RESULTS

The 10-year risks of nonfatal CHD in oral anti-diabetic drug (OAD), insulin and OAD plus insulin groups were 11.8%, 16.0%, and 16.8%, respectively. The 10-year risks of nonfatal stroke in OAD, insulin and OAD plus insulin groups were 3.0%, 3.4%, and 4.3%, respectively. In the multivariate model, chronic kidney disease (CKD), neuropathy, insulin use, calcium-channel blocker (CCB) use, higher body mass indices (BMI), low-density lipoprotein (LDL), fasting glucose, log-triglyceride (TG), and log-alanine transaminase (ALT) levels were associated with an increased CHD risk. The residual risk of stroke was associated with CKD, neuropathy, CCB use, and lower LDL cholesterol levels, higher BMI and diastolic blood pressure.

CONCLUSION

This study indicated that insulin was probably a residual risk factor of CHD but not stroke, and that there was a possible presence of obesity paradox in patients with T2DM on statin therapy. In addition to lowering TG and normalizing fasting glucose levels, lower LDL cholesterol level is better for reduction of risk of CHD on statin therapy. On the other hand, lower LDL cholesterol level could potentially be related to higher risk of stroke among populations receiving statin therapy. These findings suggest potential therapeutic targets for residual cardiovascular risk reduction in patients with T2DM on statin therapy.

New Horizons in Diabetic Neuropathies: An Updated Review on their Pathology, Diagnosis, Mechanism, Screening Techniques, Pharmacological, and Future Approaches

BACKGROUND

One of the largest problems for global public health is diabetes mellitus (DM) and its micro and macrovascular consequences. Although prevention, diagnosis, and treatment have generally improved, its incidence is predicted to keep rising over the coming years. Due to the intricacy of the molecular mechanisms, which include inflammation, oxidative stress, and angiogenesis, among others, discovering treatments to stop or slow the course of diabetic complications is still a current unmet need.

METHODS

The pathogenesis and development of diabetic neuropathies may be explained by a wide variety of molecular pathways, hexosamine pathways, such as MAPK pathway, PARP pathway, oxidative stress pathway polyol (sorbitol) pathway, cyclooxygenase pathway, and lipoxygenase pathway. Although diabetic neuropathies can be treated symptomatically, there are limited options for treating the underlying cause.

RESULT

Various pathways and screening models involved in diabetic neuropathies are discussed, along with their possible outcomes. Moreover, both medicinal and non-medical approaches to therapy are also explored.

CONCLUSION

This study highlights the probable involvement of several processes and pathways in the establishment of diabetic neuropathies and presents in-depth knowledge of new therapeutic approaches intended to stop, delay, or reverse different types of diabetic complications.

A Mitochondrial Nanoguard Modulates Redox Homeostasis and Bioenergy Metabolism in Diabetic Peripheral Neuropathy

As a major late complication of diabetes, diabetic peripheral neuropathy (DPN) is the primary reason for amputation. Nevertheless, there are no wonder drugs available. Regulating dysfunctional mitochondria is a key therapeutic target for DPN. Resveratrol (RSV) is widely proven to guard mitochondria, yet the unsatisfactory bioavailability restricts its clinical application. Tetrahedral framework nucleic acids (tFNAs) are promising carriers due to their excellent cell entrance efficiency, biological safety, and structure editability. Here, RSV was intercalated into tFNAs to form the tFNAs-RSV complexes. tFNAs-RSV achieved enhanced stability, bioavailability, and biocompatibility compared with tFNAs and RSV alone. With its treatment, reactive oxygen species (ROS) production was minimized and reductases were activated in an in vitro model of DPN. Besides, respiratory function and adenosine triphosphate (ATP) production were enhanced. tFNAs-RSV also exhibited favorable therapeutic effects on sensory dysfunction, neurovascular deterioration, demyelination, and neuroapoptosis in DPN mice. Metabolomics analysis revealed that redox regulation and energy metabolism were two principal mechanisms that were impacted during the process. Comprehensive inspections indicated that tFNAs-RSV inhibited nitrosation and oxidation and activated reductase and respiratory chain. In sum, tFNAs-RSV served as a mitochondrial nanoguard (mito-guard), representing a viable drilling target for clinical drug development of DPN.

Correlation Between Fibrinogen/Albumin and Diabetic Peripheral Neuropathy

Purpose

This study aimed to examine the correlation between fibrinogen/albumin (FAR) and diabetic peripheral neuropathy (DPN).

Patients and Methods

A total of 342 patients were included and categorized into either the DPN group or the Non-DPN (NDPN) group based on their DPN status. The FAR index was determined by calculating the ratio of fibrinogen (FIB) to serum albumin (ALB), multiplied by 100. The participants were then divided into a High-FAR group and a Low-FAR group using the median FAR value as the threshold. Neurophysiological data were collected from the participants, which included motor conduction velocity (MCV) and sensory conduction velocity (SCV).

Results

The DPN group displayed higher FAR levels [(DPN vs NDPN:6.72 (5.89,7.74) vs 5.94±1.14], in addition to slower SCV and MCV data compared to the NDPN group. The high FAR group had a higher prevalence of DPN (78.9% vs 55.6%) (P<0.05). There was a negative correlation between FAR and NCV, including bilateral median nerve SCV, left ulnar nerve SCV, bilateral median nerve MCV, bilateral common peroneal nerve MCV, bilateral tibial nerve MCV, and left ulnar nerve MCV. FAR was revealed to be an independent risk factor for the development of DPN in patients and demonstrated a greater predictive value for DPN development in Type 2 diabetes mellitus (T2DM) compared with FIB, HbA1c.

Conclusion

The results suggest that monitoring FAR levels in patients with T2DM could identify those at higher risk for developing DPN, making the FAR index a valuable predictor of DPN development. Furthermore, since FAR has an inverse relationship with NCV, it stands to reason that high FAR levels may indicate nerve damage and slower conduction velocities. Thus, managing FAR could prove beneficial in both preventing and delaying the onset of DPN in T2DM patients.

Pediatric Type 1 Diabetes: Mechanisms and Impact of Technologies on Comorbidities and Life Expectancy

Type 1 diabetes (T1D) is one of the most common chronic diseases in childhood, with a progressively increasing incidence. T1D management requires lifelong insulin treatment and ongoing health care support. The main goal of treatment is to maintain blood glucose levels as close to the physiological range as possible, particularly to avoid blood glucose fluctuations, which have been linked to morbidity and mortality in patients with T1D. Indeed, the guidelines of the International Society for Pediatric and Adolescent Diabetes (ISPAD) recommend a glycated hemoglobin (HbA1c) level < 53 mmol/mol (<7.0%) for young people with T1D to avoid comorbidities. Moreover, diabetic disease strongly influences the quality of life of young patients who must undergo continuous monitoring of glycemic values and the administration of subcutaneous insulin. In recent decades, the development of automated insulin delivery (AID) systems improved the metabolic control and the quality of life of T1D patients. Continuous subcutaneous insulin infusion (CSII) combined with continuous glucose monitoring (CGM) devices connected to smartphones represent a good therapeutic option, especially in young children. In this literature review, we revised the mechanisms of the currently available technologies for T1D in pediatric age and explored their effect on short- and long-term diabetes-related comorbidities, quality of life, and life expectation.

Peripheral Neuropathy in Diabetes Mellitus: Pathogenetic Mechanisms and Diagnostic Options

Diabetic neuropathy (DN) is one of the main microvascular complications of both type 1 and type 2 diabetes mellitus. Sometimes, this could already be present at the time of diagnosis for type 2 diabetes mellitus (T2DM), while it appears in subjects with type 1 diabetes mellitus (T1DM) almost 10 years after the onset of the disease. The impairment can involve both somatic fibers of the peripheral nervous system, with sensory-motor manifestations, as well as the autonomic system, with neurovegetative multiorgan manifestations through an impairment of sympathetic/parasympathetic conduction. It seems that, both indirectly and directly, the hyperglycemic state and oxygen delivery reduction through the vasa nervorum can determine inflammatory damage, which in turn is responsible for the alteration of the activity of the nerves. The symptoms and signs are therefore various, although symmetrical painful somatic neuropathy at the level of the lower limbs seems the most frequent manifestation. The pathophysiological aspects underlying the onset and progression of DN are not entirely clear. The purpose of this review is to shed light on the most recent discoveries in the pathophysiological and diagnostic fields concerning this complex and frequent complication of diabetes mellitus.

The conundrum of diabetic neuropathies-Past, present, and future

Diabetic neuropathy (DN) remains arguably the most prevalent chronic complication in people with both type 1 and type 2 diabetes, including in youth, despite changes in the current standards of clinical care. Additionally, emerging evidence demonstrates that neuropathy affects a large proportion of people with undiagnosed diabetes and/or prediabetes, as well as those with obesity. Here we summarize the latest epidemiology of DN, recent findings regarding the pathophysiology of the disease, as well as current outcome measures for screening and diagnosis, in research and clinical settings. The authors discuss novel perspectives on the impact of social determinants of health in DN development and management, and the latest evidence on effective therapies, including pharmacological and nonpharmacological therapies for neuropathic pain. Throughout the publication, we identify knowledge gaps and the need for future funding to address these gaps, as well as needs to advocate for a personalized care approach to reduce the burden of DN and optimize quality of life for all affected individuals.

Potential Roles of Anti-Inflammatory Plant-Derived Bioactive Compounds Targeting Inflammation in Microvascular Complications of Diabetes

Diabetes mellitus (DM) is a group of metabolic disorders, the characteristics of which include chronic hyperglycemia owing to defects in insulin function, insulin secretion, or both. Inflammation plays a crucial role in DM pathogenesis and innate immunity in the development of microvascular complications of diabetes. In addition, hyperglycemia and DM mediate a proinflammatory microenvironment that can result in various microvascular complications, including diabetic nephropathy (DNP), diabetic neuropathy (DN), and diabetic retinopathy (DR). DNP is a major cause of end-stage renal disease. DNP can lead to albuminuria, decreased filtration, mesangium expansion, thickening of the basement membrane, and eventually renal failure. Furthermore, inflammatory cells can accumulate in the interstitium and glomeruli to deteriorate DNP. DN is another most prevalent microvascular complication of DM and the main cause of high mortality, disability, and a poor quality of life. DNs have a wide range of clinical manifestations because of the types of fiber dysfunctions and complex structures of the peripheral nervous system. DR is also a microvascular and multifactorial disease, as well as a major cause of visual impairment globally. Pathogenesis of DR is yet to be fully revealed, however, numerous studies have already confirmed the role of inflammation in the onset and advancement of DR. Despite evidence, and better knowledge regarding the pathogenesis of these microvascular complications of diabetes, there is still a deficiency of effective therapies. Bioactive compounds are mainly derived from plants, and these molecules have promising therapeutic potential. In this review, evidence and molecular mechanisms regarding the role of inflammation in various microvascular complications of diabetes including DNP, DN, and DR, have been summarized. The therapeutic potential of several bioactive compounds derived from plants in the treatment of these microvascular complications of diabetes has also been discussed.

Investigation of Natural Compounds for Therapeutic Potential in Streptozotocin-induced Diabetic Neuroinflammation and Neuropathic Pain

Diabetic neuropathy (DN) is a serious microvascular complication of diabetes mellitus (DM) that impacts the nervous system. Several risk factors are involved in the progression and maintenance of DN-associated pain, such as higher expression of various inflammatory mediators, e.g., tumor necrotic factor-alpha (TNF-α), nuclear factor-kappa B (NF-κB), and cyclo-oxygenase-2 (COX-2). The present research explores the neuroprotective potential of natural isolates, including berbamine, bergapten, and carveol, on the DM-induced neuroinflammation and neurodegeneration that cause neuropathic pain. The study utilized computerized techniques, including computational analysis (a docking assay and a molecular dynamic simulation) before moving to in vivo protocols. Diabetic neuropathy was induced by intraperitonial injection (IP) of streptozotocin (65 mg/kg), and the animal subjects (rats) were kept for 4 weeks for the development of DN. Once diabetic neuropathy was confirmed, the subjects were treated with berbamine, bergapten, and carveol until the sixth week (i.e., 2 weeks of treatment). At the sixth week, the rats were sacrificed, and the sciatic nerve and spinal cord of each was collected for further molecular investigation. Docking and a molecular dynamic simulation (MDS) delivered the information that the natural compounds (berbamine, bergapten, and carveol) were interacting with the selected target protein (i.e., mitogen-activated protein kinase). After IP, it was found that berbamine, bergapten, and carveol had ameliorated mechanical allodynia and thermal hyperalgesia by the 28th day of the study (2 weeks after treatment) without affecting blood glucose levels. Berbamine, bergapten, and carveol markedly elevated the levels of glutathione (GSH) and glutathione s-transferase (GST), in both the sciatic nerve and spinal cord, and also reduced lipid peroxidase (LPO) and nitric oxide (NO). The abovementioned natural isolates reduced pathologic alterations provoked through DN, a finding confirmed through histopathological assays (hematoxylin and eosin staining and immuno-histochemical analysis). Treatment down regulated higher expressions of the inflammatory mediatorcyclooxygenase-2 (COX-2), tumor necrosis factor-α (TNF-α), and nuclear factor kappa B (NF-κB), as confirmed by ELISA and polymerase chain reaction (PCR). The outcomes of berbamine, bergapten, and carveol are compared with those of pregabalin as a positive control group. Compared to pregabalin, treatment with the aforementioned three natural compounds improved nociception and reduced hyperalgesic effects, and consequently reduced pain perception and inflammation. Our results suggest the mechanism for the neuro-protective impact of berbamine, bergapten, and carveol might possibly be arbitrated via COX-2, TNF-α, and NF-κB, and regulated by mitogen-activated protein kinase, ultimately ameliorating STZ-provoked, DM-induced neuroinflammation and neurodegeneration, and associated neuropathic pain.

Obesity-Associated Neuropathy: Recent Preclinical Studies and Proposed Mechanisms

Significance: The prevalence of metabolic syndrome (MetS) and associated obesity has increased in recent years, affecting millions worldwide. One of the most common complications of obesity is damage to the peripheral nerve system, referred to as neuropathy. The lack of disease-modifying therapy for this complication is largely due to a poor understanding of the complex neurobiology underlying neuropathy. Recent preclinical studies suggest that in addition to glucotoxic events, other mechanisms, including lipid signaling, microbiome, or inflammation, may be viable targets to prevent nerve damage and neuropathic pain in obesity. Recent Advances: Clinical and preclinical studies using diet-induced obesity rodent models have identified novel interventions that improve neuropathy. Notably, mechanistic studies suggest that lipid, calcium signaling, and inflammation are converging pathways. Critical Issues: In this review, we focus on interventions and their mechanisms that are shown to ameliorate neuropathy in MetS obese models, including: (i) inhibition of a sensory neuron population, (ii), modification of dietary components, (iii) activation of nuclear and mitochondrial lipid pathways, (iv) exercise, and (v) modulation of gut microbiome composition and their metabolites. Future Directions: These past years, novel research increased our knowledge about neuropathy in obesity and discovered the involvement of nonglucose signaling. More studies are necessary to uncover the interplay between complex metabolic pathways in the peripheral nerve system of obese individuals. Further mechanistic studies in preclinical models and humans are crucial to create single- or multitarget interventions for this complex disease implying complex metabolic phenotyping. Antioxid. Redox Signal. 37, 597-612.

Association between Dietary Inflammatory Index Scores and Diabetes Sensorimotor Polyneuropathy in Patients with Type 2 Diabetes Mellitus: A Case-Control Study

Background

Diabetes sensorimotor polyneuropathy (DSPN) is a common complication of diabetes. Diet has been previously related to DSPN. However, no studies have investigated the relationship between the inflammatory potential of the whole diet and DSPN. So, we aimed to examine the association between dietary inflammatory index (DII) and DSPN in Iranian adults.

Methods

A total of 185 subjects with DSPN and 185 sex- and age-matched controls were selected in this case-control study. A 168-item validated food frequency questionnaire (FFQ) was used to assay dietary intakes. DII was calculated based on the developed formula. The Toronto clinical neuropathy score was applied to define DSPN. Binary logistic regression was used to estimate the odds ratios (ORs) and 95% confidence intervals (95% CIs) of DII in relation to DSPN.

Results

Mean values of age and BMI for all the participants were reported as 50.79 and 28.60, respectively. Also, the median (IQR) of DII for all the participants was estimated as −0.091 (−0.93, 1.07). Our findings suggest that participants in the highest quartile of the DII had higher odds of DSPN (OR = 1.76; 95% CI: 1.03, 3.36) (p-trend = 0.01) compared to subjects in the lowest quartile of DII scores after adjustment for age and sex. Additionally, a strong association was observed after adjusting for energy intake, physical activity, education, smoking status, economic status, marital status, job, BMI, and WC in model 2 (OR = 2.23, 95% CI = 1.13–4.39) (p-trend = 0.0048).

Conclusion

Higher DII score was associated with an increased risk of DSPN. Therefore, it is possible that a diet rich in anti-inflammatory nutrients and foods could improve and prevent DSPN.

Altered Circulating microRNAs in Patients with Diabetic Neuropathy and Corneal Nerve Loss: A Pilot Study

An alteration in circulating miRNAs may have important diagnostic and therapeutic relevance in diabetic neuropathy. Patients with type 2 diabetes mellitus (T2DM) underwent an assessment of neuropathic symptoms using Douleur Neuropathique 4 (DN4), the vibration perception threshold (VPT) using a Neurothesiometer, sudomotor function using the Sudoscan, corneal nerve morphology using corneal confocal microscopy (CCM) and circulating miRNAs using high-throughput miRNA expression profiling. Patients with T2DM, with (n = 9) and without (n = 7) significant corneal nerve loss were comparable in age, gender, diabetes duration, BMI, HbA1c, eGFR, blood pressure, and lipid profile. The VPT was significantly higher (p < 0.05), and electrochemical skin conductance (p < 0.05), corneal nerve fiber density (p = 0.001), corneal nerve branch density (p = 0.013), and corneal nerve fiber length (p < 0.001) were significantly lower in T2DM patients with corneal nerve loss compared to those without corneal nerve loss. Following a q-PCR-based analysis of total plasma microRNAs, we found that miR-92b-3p (p = 0.008) was significantly downregulated, while miR-22-3p (p = 0.0001) was significantly upregulated in T2DM patients with corneal nerve loss. A network analysis revealed that these miRNAs regulate axonal guidance and neuroinflammation genes. These data support the need for more extensive studies to better understand the role of dysregulated miRNAs’ in diabetic neuropathy.

An Insight into Potential Pharmacotherapeutic Agents for Painful Diabetic Neuropathy

Diabetes is the 4th most common disease affecting the world's population. It is accompanied by many complications that deteriorate the quality of life. Painful diabetic neuropathy (PDN) is one of the debilitating consequences of diabetes that effects one-third of diabetic patients. Unfortunately, there is no internationally recommended drug that directly hinders the pathological mechanisms that result in painful diabetic neuropathy. Clinical studies have shown that anticonvulsant and antidepressant therapies have proven fruitful in management of pain associated with PDN. Currently, the FDA approved medications for painful diabetic neuropathies include duloxetine, pregabalin, tapentadol extended release, and capsaicin (for foot PDN only). The FDA has also approved the use of spinal cord stimulation system for the treatment of diabetic neuropathy pain. The drugs recommended by other regulatory bodies include gabapentin, amitriptyline, dextromethorphan, tramadol, venlafaxine, sodium valproate, and 5 % lidocaine patch. These drugs are only partially effective and have adverse effects associated with their use. Treating painful symptoms in diabetic patient can be frustrating not only for the patients but also for health care workers, so additional clinical trials for novel and conventional treatments are required to devise more effective treatment for PDN with minimal side effects. This review gives an insight on the pathways involved in the pathogenesis of PDN and the potential pharmacotherapeutic agents. This will be followed by an overview on the FDA-approved drugs for PDN and commercially available topical analgesic and their effects on painful diabetic neuropathies.

Role of miRNAs in diabetic neuropathy: mechanisms and possible interventions

Accelerating cases of diabetes worldwide have given rise to higher incidences of diabetic complications. MiRNAs, a much-explored class of non-coding RNAs, play a significant role in the pathogenesis of diabetes mellitus by affecting insulin release, β-cell proliferation, and dysfunction. Besides, disrupted miRNAs contribute to various complications, diabetic retinopathy, nephropathy, and neuropathy as well as severe conditions like diabetic foot. MiRNAs regulate various processes involved in diabetic complications like angiogenesis, vascularization, inflammations, and various signaling pathways like PI3K, MAPK, SMAD, and NF-KB signaling pathways. Diabetic neuropathy is the most common diabetic complication, characterized mainly by pain and numbness, especially in the legs and feet. MiRNAs implicated in diabetic neuropathy include mir-9, mir-106a, mir-146a, mir-182, miR-23a and b, miR-34a, and miR-503. The diabetic foot is the most common diabetic neuropathy, often leading to amputations. Mir-203, miR-23c, miR-145, miR-29b and c, miR-126, miR-23a and b, miR-503, and miR-34a are associated with diabetic foot. This review has been compiled to summarize miRNA involved in initiation, progression, and miRNAs affecting various signaling pathways involved in diabetic neuropathy including the diabetic foot. Besides, potential applications of miRNAs as biomarkers and therapeutic targets in this microvascular complication will also be discussed.

A Comprehensive Review of Neuronal Changes in Diabetics

There has been an exponential rise in diabetes mellitus (DM) cases on a global scale. Diabetes affects almost every system of the body, and the nervous system is no exception. Although the brain is dependent on glucose, providing it with the energy required for optimal functionality, glucose also plays a key role in the regulation of oxidative stress, cell death, among others, which furthermore contribute to the pathophysiology of neurological disorders. The variety of biochemical processes engaged in this process is only matched by the multitude of clinical consequences resulting from it. The wide-ranging effects on the central and peripheral nervous system include, but are not limited to axonopathies, neurodegenerative diseases, neurovascular diseases, and general cognitive impairment. All language search was conducted on MEDLINE, COCHRANE, EMBASE, and GOOGLE SCHOLAR till September 2021. The following search strings and Medical Subject Headings (MeSH terms) were used: "Diabetes Mellitus," "CNS," "Diabetic Neuropathy," and "Insulin." We explored the literature on diabetic neuropathy, covering its epidemiology, pathophysiology with the respective molecular pathways, clinical consequences with a special focus on the central nervous system and finally, measures to prevent and treat neuronal changes. Diabetes is slowly becoming an epidemic, rapidly increasing the clinical burden on account of its wide-ranging complications. This review focuses on the neuronal changes occurring in diabetes such as the impact of hyperglycemia on brain function and structure, its association with various neurological disorders, and a few diabetes-induced peripheral neuropathic changes. It is an attempt to summarize the relevant literature about neuronal consequences of DM as treatment options available today are mostly focused on achieving better glycemic control; further research on novel treatment options to prevent or delay the progression of neuronal changes is still needed.

Toll-Like Receptor 2 Antagonist Ameliorates Type 2 Diabetes Mellitus Associated Neuropathic Pain by Repolarizing Pro-inflammatory Macrophages

Diabetic neuropathy is one of the common complications of type 2 diabetes mellitus (T2DM) with severe outcomes. The mechanisms of physiopathology of diabetic neuropathy are not well elucidated. Inflammation and inflammatory macrophages are recognized to be crucial in diabetic neuropathy. Toll-like receptor 2 (TLR2) is an important factor in innate immune response which could promote the polarization of inflammatory macrophages. In present study, we evaluated the effects of a TLR2 antagonist CU-CPT22 on diabetic neuropathy. We induced T2DM in mice by feeding with high fat diet (HFD). We measured the body weight, blood glucose level, paw withdrawal threshold, inflammatory cytokine production, and macrophages infiltration in T2DM mice. We evaluated the effects of CU-CPT22 on pro-inflammatory cytokines production, macrophage marker expression in lipopolysaccharides (LPS)-treated BMDMs. We administrated CU-CPT22 in T2DM mice and measured the pro-inflammatory cytokines levels, expression of macrophages markers in sciatic nerve (SCN), and paw withdrawal threshold. T2DM mice had significantly increased body weight and blood glucose, and had significantly decreased paw withdrawal threshold. Obvious increased pro-inflammatory cytokine level and infiltration of M1 phenotype macrophages was observed in SCN from T2DM mice. CU-CPT22 prevented pro-inflammatory cytokine production in LPS-treated BMDMs and re-polarized them to M2 phenotype. CU-CPT22 suppressed the inflammation and induced M2 macrophages in SCN from T2DM mice, and ameliorated the paw withdrawal threshold in T2DM mice. CU-CPT22 ameliorates neuropathic pain in T2DM by promoting M2 phenotype macrophages.

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.

Evolving concepts on the role of dyslipidemia, bioenergetics, and inflammation in the pathogenesis and treatment of diabetic peripheral neuropathy

Diabetic peripheral neuropathy (DPN) is one of the most widespread and disabling neurological conditions, accounting for half of all neuropathy cases worldwide. Despite its high prevalence, no approved disease modifying therapies exist. There is now a growing body of evidence that DPN secondary to type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM) represents different disease processes, with T2DM DPN best understood within the context of metabolic syndrome rather than hyperglycemia. In this review, we highlight currently understood mechanisms of DPN, along with their corresponding potential therapeutic targets. We frame this discussion within a practical overview of how the field evolved from initial human observations to murine pathomechanistic and therapeutic models into ongoing and human clinical trials, with particular emphasis on T2DM DPN and metabolic syndrome.

Inflammatory biomarkers as a part of diagnosis in diabetic peripheral neuropathy

Diabetic peripheral neuropathy (DPN), a chronic neurological complication of diabetes mellitus, remains scantily addressed area of research. Many lacunae in the temporal sequence between cause and effect of DPN still remain unfilled and therefore treatment of DPN remains unsatisfactory. This is largely due to the conventional glucocentric focus to resolve the problem. This focus over hyperglycemia should be shifted to consider, chronic low grade inflammation as the major determinant in DPN. Rapidly emerging evidences from recent studies suggest that chronic low grade inflammation leads to the activation of innate immune system response, loss of insulin signaling and insulin resistance, endoplasmic reticulum stress, mitochondrial stress, leading to production of kinases like protein kinase C, mitogen activated protein kinase and jun-N-terminal kinase, pro-inflammatory cytokines and inter leukins-1b, 2, 6 and 8, tumour necrosis factor-alpha and other chemokines, leading to DPN. These biomarkers can be early predictors of DPN and therefore should be the focus of work testing their clinical utility to identify high-risk individuals as well as perhaps to target interventions. In this paper, we would like to review all the aspects of DPN, laying greater emphasis on inflammatory biomarkers as a tool for early diagnosis of DPN and the possible research approaches to address it satisfactorily.

The Emerging Role of COX-2, 15-LOX and PPARγ in Metabolic Diseases and Cancer: An Introduction to Novel Multi-target Directed Ligands (MTDLs)

Emerging evidence supports an intertwining framework for the involvement of different inflammatory pathways in a common pathological background for a number of disorders. Of importance are pathways involving arachidonic acid metabolism by cyclooxygenase-2 (COX-2) and 15-lipoxygenase (15-LOX). Both enzyme activities and their products are implicated in a range of pathophysiological processes encompassing metabolic impairment leading to adipose inflammation and the subsequent vascular and neurological disorders, in addition to various pro- and antitumorigenic effects. A further layer of complexity is encountered by the disparate, and often reciprocal, modulatory effect COX-2 and 15-LOX activities and metabolites exert on each other or on other cellular targets, the most prominent of which is peroxisome proliferator-activated receptor gamma (PPARγ). Thus, effective therapeutic intervention with such multifaceted disorders requires the simultaneous modulation of more than one target. Here, we describe the role of COX-2, 15-LOX, and PPARγ in cancer and complications of metabolic disorders, highlight the value of designing multi-target directed ligands (MTDLs) modifying their activity, and summarizing the available literature regarding the rationale and feasibility of design and synthesis of these ligands together with their known biological effects. We speculate on the potential impact of MTDLs in these disorders as well as emphasize the need for structured future effort to translate these early results facilitating the adoption of these, and similar, molecules in clinical research.

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.

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.

Diabetic neuropathy and neuropathic pain: a (con)fusion of pathogenic mechanisms?

Neuropathy is a common complication of long-term diabetes that impairs quality of life by producing pain, sensory loss and limb amputation. The presence of neuropathy in both insulin-deficient (type 1) and insulin resistant (type 2) diabetes along with the slowing of progression of neuropathy by improved glycemic control in type 1 diabetes has caused the majority of preclinical and clinical investigations to focus on hyperglycemia as the initiating pathogenic lesion. Studies in animal models of diabetes have identified multiple plausible mechanisms of glucotoxicity to the nervous system including post-translational modification of proteins by glucose and increased glucose metabolism by aldose reductase, glycolysis and other catabolic pathways. However, it is becoming increasingly apparent that factors not necessarily downstream of hyperglycemia can also contribute to the incidence, progression and severity of neuropathy and neuropathic pain. For example, peripheral nerve contains insulin receptors that transduce the neurotrophic and neurosupportive properties of insulin, independent of systemic glucose regulation, while the detection of neuropathy and neuropathic pain in patients with metabolic syndrome and failure of improved glycemic control to protect against neuropathy in cohorts of type 2 diabetic patients has placed a focus on the pathogenic role of dyslipidemia. This review provides an overview of current understanding of potential initiating lesions for diabetic neuropathy and the multiple downstream mechanisms identified in cell and animal models of diabetes that may contribute to the pathogenesis of diabetic neuropathy and neuropathic pain.

Electroacupuncture Alleviates Diabetic Peripheral Neuropathy by Regulating Glycolipid-Related GLO/AGEs/RAGE Axis

Diabetic peripheral neuropathy (DPN) is one of the most common complications of diabetes mellitus (DM) and affects over one-third of all patients. Neuropathic pain and nerve dysfunction induced by DM is related to the increase of advanced glycation end products (AGEs) produced by reactive dicarbonyl compounds in a hyperglycemia environment. AGEs induce the expression of pro-inflammatory cytokines via the main receptor (RAGE), which has been documented to play a crucial role in the pathogenesis of diabetic peripheral neuropathy. Electroacupuncture (EA) has been reported to have a positive effect on paralgesia caused by various diseases, but the mechanism is unclear. In this study, we used high-fat-fed low-dose streptozotocin-induced rats as a model of type 2 diabetes (T2DM). Persistent metabolic disorder led to mechanical and thermal hyperalgesia, as well as intraepidermal nerve fiber density reduction and nerve demyelination. EA improved neurological hyperalgesia, decreased the pro-inflammatory cytokines, reduced the generation of AGEs and RAGE, and regulated the glyoxalase system in the EA group. Taken together, our study suggested that EA plays a role in the treatment of T2DM-induced DPN, and is probably related to the regulation of metabolism and the secondary influence on the GLO/AGE/RAGE axis.

Satellite glia as a critical component of diabetic neuropathy: Role of lipocalin-2 and pyruvate dehydrogenase kinase-2 axis in the dorsal root ganglion

Diabetic peripheral neuropathy (DPN) is a common complication of uncontrolled diabetes. The pathogenesis of DPN is associated with chronic inflammation in dorsal root ganglion (DRG), eventually causing structural and functional changes. Studies on DPN have primarily focused on neuronal component, and there is limited knowledge about the role of satellite glial cells (SGCs), although they completely enclose neuronal soma in DRG. Lipocalin-2 (LCN2) is a pro-inflammatory acute-phase protein found in high levels in diverse neuroinflammatory and metabolic disorders. In diabetic DRG, the expression of LCN2 was increased exclusively in the SGCs. This upregulation of LCN2 in SGCs correlated with increased inflammatory responses in DRG and sciatic nerve. Furthermore, diabetes-induced inflammation and morphological changes in DRG, as well as sciatic nerve, were attenuated in Lcn2 knockout (KO) mice. Lcn2 gene ablation also ameliorated neuropathy phenotype as determined by nerve conduction velocity and intraepidermal nerve fiber density. Mechanistically, studies using specific gene KO mice, adenovirus-mediated gene overexpression strategy, and primary cultures of DRG SGCs and neurons have demonstrated that LCN2 enhances the expression of mitochondrial gate-keeping regulator pyruvate dehydrogenase kinase-2 (PDK2) through PPARβ/δ, thereby inhibiting pyruvate dehydrogenase activity and increasing production of glycolytic end product lactic acid in DRG SGCs and neurons of diabetic mice. Collectively, our findings reveal a crucial role of glial LCN2-PPARβ/δ-PDK2-lactic acid axis in progression of DPN. Our results establish a link between pro-inflammatory LCN2 and glycolytic PDK2 in DRG SGCs and neurons and propose a novel glia-based mechanism and drug target for therapy of DPN. MAIN POINTS: Diabetes upregulates LCN2 in satellite glia, which in turn increases pyruvate dehydrogenase kinase-2 (PDK2) expression and lactic acid production in dorsal root ganglia (DRG). Glial LCN2-PDK2-lactic acid axis in DRG plays a crucial role in the pathogenesis of diabetic neuropathy.

Plant Compounds for the Treatment of Diabetes, a Metabolic Disorder: NF-κB as a Therapeutic Target

Background:

The prevalence of diabetes in the world population hás reached 8.8 % and is expected to rise to 10.4% by 2040. Hence, there is an urgent need for the discovery of drugs against therapeutic targets to sojourn its prevalence. Previous studies proved that NF-κB serves as a central agent in the development of diabetic complications.

Objectives:

This review intended to list the natural plant compounds that would act as inhibitors of NF-κB signalling in different organs under the diabetic condition with their possible mechanism of action.

Methods:

Information on NF-κB, diabetes, natural products, and relation in between them, was gathered from scientific literature databases such as Pubmed, Medline, Google scholar, Science Direct, Springer, Wiley online library.

Results and Conclusion:

NF-κB plays a crucial role in the development of diabetic complications because of its link in the expression of genes that are responsible for organs damage such as kidney, brain, eye, liver, heart, muscle, endothelium, adipose tissue and pancreas by inflammation, apoptosis and oxidative stress. Activation of PPAR-α, SIRT3/1, and FXR through many cascades by plant compounds such as terpenoids, iridoids, flavonoids, alkaloids, phenols, tannins, carbohydrates, and phytocannabinoids recovers diabetic complications. These compounds also exhibit the prevention of NF-κB translocation into the nucleus by inhibiting NF-κB activators, such as VEGFR, RAGE and TLR4 receptors, which in turn, prevent the activation of many genes involved in tissue damage. Current knowledge on the treatment of diabetes by targeting NF-κB is limited, so future studies would enlighten accordingly.

Metabolic syndrome and peripheral neuropathy

Diabetic peripheral neuropathy and metabolic syndrome (MetS) are both global health challenges with well-established diagnostic criteria and significant impacts on quality of life. Clinical observations, epidemiologic evidence, and animal models of disease have strongly suggested MetS is associated with an elevated risk for cryptogenic sensory peripheral neuropathy (CSPN). MetS neuropathy preferentially affects small unmyelinated axons early in its course, and it may also affect autonomic and large fibers. CSPN risk is linked to MetS and several of its components including obesity, dyslipidemia, and prediabetes. MetS also increases neuropathy risk in patients with established type 1 and type 2 diabetes. In this review we present animal data regarding the role of inflammation and dyslipidemia in MetS neuropathy pathogenesis. Several studies suggest exercise-based lifestyle modification is a promising treatment approach for MetS neuropathy.

Managing diabetic foot in times of COVID-19: time to put the best 'foot' forward

Introduction

The COVID-19 pandemic has had an unparalleled impact on the socio-economic and healthcare structure of India. Due to our large populations of diabetic patients, who have an increased risk of worse outcomes with COVID-19 infection, it is of utmost public health importance to analyse the relationship between the two. The aim of our review was to analyse the possible relationship between COVID-19 infection and DFUs, which are a fairly common, yet serious complication in diabetic patients, as well as their management, under the given changing circumstances.

Methodology

An extensive review of related educational articles was analysed from various databases.

Results

The two main pathogenic mechanisms described in COVID-19 infection are a cytokine storm (causing ARDS) as well as an acquired coagulopathy, with widespread thrombosis. DFUs are associated with an underlying peripheral neuropathy, a chronic low-grade inflammatory state and peripheral arterial disease, which lead to chronic non-healing ulcers. Similarities seen in the pathogenic mechanisms of these two conditions make a bidirectional relationship highly plausible.

Conclusion

Due to the disruptions in the healthcare system brought on by the COVID-19 pandemic, changes in practice to a telehealth-driven approach, with emphasis on homecare and community clinics, need to be adopted, to ensure best possible care to patients with DFUs, in order to reduce their risk of DFU-related complications and need for hospitalization.

DW14006 as a Direct AMPKα Activator Ameliorates Diabetic Peripheral Neuropathy in Mice

Diabetic peripheral neuropathy (DPN) is a long-term complication of diabetes with a complicated pathogenesis. AMP-activated protein kinase (AMPK) senses oxidative stress, and mitochondrial function plays a central role in the regulation of DPN. Here, we reported that DW14006 (2-[3-(7-chloro-6-[2'-hydroxy-(1,1'-biphenyl)-4-yl]-2-oxo-1,2-dihydroquinolin-3-yl)phenyl]acetic acid) as a direct AMPKα activator efficiently ameliorated DPN in both streptozotocin (STZ)-induced type 1 and BKS db/db type 2 diabetic mice. DW14006 administration highly enhanced neurite outgrowth of dorsal root ganglion neurons and improved neurological function in diabetic mice. The underlying mechanisms have been intensively investigated. DW14006 treatment improved mitochondrial bioenergetics profiles and restrained oxidative stress and inflammation in diabetic mice by targeting AMPKα, which has been verified by assay against the STZ-induced diabetic mice injected with adeno-associated virus 8-AMPKα-RNAi. To our knowledge, our work might be the first report on the amelioration of the direct AMPKα activator on DPN by counteracting multiple risk factors including mitochondrial dysfunction, oxidative stress, and inflammation, and DW14006 has been highlighted as a potential leading compound in the treatment of DPN.

Reactive dicarbonyl compounds cause Calcitonin Gene-Related Peptide release and synergize with inflammatory conditions in mouse skin and peritoneum

The plasmas of diabetic or uremic patients and of those receiving peritoneal dialysis treatment have increased levels of the glucose-derived dicarbonyl metabolites like methylglyoxal (MGO), glyoxal (GO), and 3-deoxyglucosone (3-DG). The elevated dicarbonyl levels can contribute to the development of painful neuropathies. Here, we used stimulated immunoreactive Calcitonin Gene-Related Peptide (iCGRP) release as a measure of nociceptor activation, and we found that each dicarbonyl metabolite induces a concentration-, TRPA1-, and Ca²⁺-dependent iCGRP release. MGO, GO, and 3-DG were about equally potent in the millimolar range. We hypothesized that another dicarbonyl, 3,4-dideoxyglucosone-3-ene (3,4-DGE), which is present in peritoneal dialysis (PD) solutions after heat sterilization, activates nociceptors. We also showed that at body temperatures 3,4-DGE is formed from 3-DG and that concentrations of 3,4-DGE in the micromolar range effectively induced iCGRP release from isolated murine skin. In a novel preparation of the isolated parietal peritoneum PD fluid or 3,4-DGE alone, at concentrations found in PD solutions, stimulated iCGRP release. We also tested whether inflammatory tissue conditions synergize with dicarbonyls to induce iCGRP release from isolated skin. Application of MGO together with bradykinin or prostaglandin E₂ resulted in an overadditive effect on iCGRP release, whereas MGO applied at a pH of 5.2 resulted in reduced release, probably due to an MGO-mediated inhibition of transient receptor potential (TRP) V1 receptors. These results indicate that several reactive dicarbonyls activate nociceptors and potentiate inflammatory mediators. Our findings underline the roles of dicarbonyls and TRPA1 receptors in causing pain during diabetes or renal disease.

Cardiovascular autonomic neuropathy: A silent killer with long reach

Cardiovascular autonomic neuropathy (CAN) is a common and deadly complication of diabetes mellitus, which is frequently overlooked in clinical practice due to its characteristic subtle presentation earlier in disease. Yet, timely detection of CAN may help implementation of tailored interventions to prevent its progression and mitigate the risk of associated complications, including cardiovascular disease (CVD), cardiac arrhythmias, myocardial dysfunction leading to congestive heart failure and all-cause mortality. This review highlights current CAN epidemiology trends, novel mechanisms linking CAN with other diabetes complications and current recommendations for diagnosis and management of the disease in the clinical setting.

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 .

Specialized pro-resolving mediators in diabetes: novel therapeutic strategies

Diabetes mellitus (DM) is an important metabolic disorder characterized by persistent hyperglycemia resulting from inadequate production and secretion of insulin, impaired insulin action, or a combination of both. Genetic disorders and insulin receptor disorders, environmental factors, lifestyle choices and toxins are key factors that contribute to DM. While it is often referred to as a metabolic disorder, modern lifestyle choices and nutrient excess induce a state of systemic chronic inflammation that results in the increased production and secretion of inflammatory cytokines that contribute to DM. It is chronic hyperglycemia and the low-grade chronic-inflammation that underlies the development of microvascular and macrovascular complications leading to damage in a number of tissues and organs, including eyes, vasculature, heart, nerves, and kidneys. Improvements in the management of risk factors have been beneficial, including focus on intensified glycemic control, but most current approaches only slow disease progression. Even with recent studies employing SGLT2 inhibitors demonstrating protection against cardiovascular and kidney diseases, kidney function continues to decline in people with established diabetic kidney disease (DKD). Despite the many advances and a greatly improved understanding of the pathobiology of diabetes and its complications, there remains a major unmet need for more effective therapeutics to prevent and reverse the chronic complications of diabetes. More recently, there has been growing interest in the use of specialised pro-resolving mediators (SPMs) as an exciting therapeutic strategy to target diabetes and the chronic complications of diabetes.

Ameliorative Effect of Berberine on Neonatally Induced Type 2 Diabetic Neuropathy via Modulation of BDNF, IGF-1, PPAR-γ, and AMPK Expressions

Neonatal-streptozotocin (n-STZ)-induced diabetes mimics most of the clinicopathological symptoms of type 2 diabetes mellitus (T2DM) peripheral neuropathy. Berberine, a plant alkaloid, is reported to have antidiabetic, antioxidant, anti-inflammatory, and neuroprotective potential. The aim of the present study was to investigate the potential of berberine against n-STZ-induced painful diabetic peripheral polyneuropathy by assessing various biochemical, electrophysiological, morphological, and ultrastructural studies. Type 2 diabetes mellitus was produced neonatal at the age of 2 days (10-12 g) by STZ (90 mg/kg intraperitoneal). After confirmation of neuropathy at 6 weeks, rats were treated with berberine (10, 20, and 40 mg/kg). Administration of n-STZ resulted in T2DM-induced neuropathic pain reflected by a significant alterations (P < .05) in hyperalgesia, allodynia, and motor as well as sensory nerve conduction velocities whereas berberine (20 and 40 mg/kg) treatment significantly attenuated (P < .05) these alterations. Berberine treatment significantly inhibited (P < .05) STZ-induced alterations in aldose reductase, glycated hemoglobin, serum insulin, hepatic cholesterol, and triglyceride levels. The elevated oxido-nitrosative stress and decreased Na-K-ATPase and pulse Ox levels were significantly attenuated (P < .05) by berberine. It also significantly downregulated (P < .05) neural tumor necrosis factor-α (TNF-α), interleukin (IL)-1β and IL-6 messenger RNA (mRNA), and protein expressions both. Streptozotocin-induced downregulated mRNA expressions of brain-derived neurotrophic factor (BDNF), insulin-like growth factor (IGF-1), and peroxisome proliferator-activated receptors-γ (PPAR-γ) in sciatic nerve were significantly upregulated (P < .05) by berberine. Western blot analysis revealed that STZ-induced alterations in adenosine monophosphate protein kinase (AMPK; Thr-172) and protein phosphatase 2C-α protein expressions in dorsal root ganglia were inhibited by berberine. It also attenuated histological and ultrastructural alterations induced in sciatic nerve by STZ. In conclusion, berberine exerts its neuroprotective effect against n-STZ-induced diabetic peripheral neuropathy via modulation of pro-inflammatory cytokines (TNF α, IL-1β, and IL-6), oxido-nitrosative stress, BDNF, IGF-1, PPAR-γ, and AMPK expression to ameliorate impaired allodynia, hyperalgesia, and nerve conduction velocity during T2DM.

Nanoparticle-microRNA-146a-5p polyplexes ameliorate diabetic peripheral neuropathy by modulating inflammation and apoptosis

Nontoxic and nonimmunogenic nanoparticles play an increasingly important role in the application of pharmaceutical nanocarriers. The pathogenesis of diabetic peripheral neuropathy (DPN) has been extensively studied. However, the role of microRNAs in DPN remains to be clarified. We verified in vitro that miR-146a-5p mimics inhibited the expression of proinflammatory cytokines and apoptosis. Then, we explored the protective effect of nanoparticle-miRNA-146a-5p polyplexes (nano-miR-146a-5p) on DPN rats. We demonstrated that nano-miR-146a-5p improved nerve conduction velocity and alleviated the morphological damage and demyelination of the sciatic nerve of DPN rats. The expression of the inflammatory cytokines, caspase-3, and cleaved caspase-3 in the sciatic nerve was inhibited by nano-miR-146a-5p. Additionally, nano-miR-146a-5p increased the expression of myelin basic protein. These results all indicated that nano-miR-146a-5p had a protective effect on peripheral nerves in the DPN rat model, which may occur through the regulation of the inflammatory response and apoptosis.

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.

Preventive action of benztropine on platinum-induced peripheral neuropathies and tumor growth

The endogenous cholinergic system plays a key role in neuronal cells, by suppressing neurite outgrowth and myelination and, in some cancer cells, favoring tumor growth. Platinum compounds are widely used as part of first line conventional cancer chemotherapy; their efficacy is however limited by peripheral neuropathy as a major side-effect. In a multiple sclerosis mouse model, benztropine, that also acts as an anti-histamine and a dopamine re-uptake inhibitor, induced the differentiation of oligodendrocytes through M1 and M3 muscarinic receptors and enhanced re-myelination. We have evaluated whether benztropine can increase anti-tumoral efficacy of oxaliplatin, while preventing its neurotoxicity.We showed that benztropine improves acute and chronic clinical symptoms of oxaliplatin-induced peripheral neuropathies in mice. Sensory alterations detected by electrophysiology in oxaliplatin-treated mice were consistent with a decreased nerve conduction velocity and membrane hyperexcitability due to alterations in the density and/or functioning of both sodium and potassium channels, confirmed by action potential analysis from ex-vivo cultures of mouse dorsal root ganglion sensory neurons using whole-cell patch-clamp. These alterations were all prevented by benztropine. In oxaliplatin-treated mice, MBP expression, confocal and electronic microscopy of the sciatic nerves revealed a demyelination and confirmed the alteration of the myelinated axons morphology when compared to animals injected with oxaliplatin plus benztropine. Benztropine also prevented the decrease in neuronal density in the paws of mice injected with oxaliplatin. The neuroprotection conferred by benztropine against chemotherapeutic drugs was associated with a lower expression of inflammatory cytokines and extended to diabetic-induced peripheral neuropathy in mice.Mice receiving benztropine alone presented a lower tumor growth when compared to untreated animals and synergized the anti-tumoral effect of oxaliplatin, a phenomenon explained at least in part by benztropine-induced ROS imbalance in tumor cells.This report shows that blocking muscarinic receptors with benztropine prevents peripheral neuropathies and increases the therapeutic index of oxaliplatin. These results can be rapidly transposable to patients as benztropine is currently indicated in Parkinson's disease in the United States.

Glucagon-Like Peptide-1 Receptor Agonist Protects Dorsal Root Ganglion Neurons against Oxidative Insult

OBJECTIVE

Diabetic polyneuropathy (DPN) is one of the most prevalent diabetic complications. We previously demonstrated that exendin-4 (Ex4), a glucagon-like peptide-1 receptor agonist (GLP-1RA), has beneficial effects in animal models of DPN. We hypothesized that GLP-1 signaling would protect neurons of the peripheral nervous system from oxidative insult in DPN. Here, the therapeutic potential of GLP-1RAs on DPN was investigated in depth using the cellular oxidative insult model applied to the dorsal root ganglion (DRG) neuronal cell line.

RESEARCH DESIGN AND METHODS

Immortalized DRG neuronal 50B11 cells were cultured with and without hydrogen peroxide in the presence or absence of Ex4 or GLP-1(7-37). Cytotoxicity and viability were determined using a lactate dehydrogenase assay and MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium inner salt), respectively. Antioxidant enzyme activity was evaluated using a superoxide dismutase assay. Alteration of neuronal characteristics of 50B11 cells induced by GLP-1RAs was evaluated with immunocytochemistry utilizing antibodies for transient receptor potential vanilloid subfamily member 1, substance P, and calcitonin gene-related peptide. Cell proliferation and apoptosis were also examined by ethynyl deoxyuridine incorporation assay and APOPercentage dye, respectively. The neurite projection ratio induced by treatment with GLP-1RAs was counted. Intracellular activation of adenylate cyclase/cyclic adenosine monophosphate (cAMP) signaling was also quantified after treatment with GLP-1RAs.

RESULTS

Neither Ex4 nor GLP-1(7-37) demonstrated cytotoxicity in the cells. An MTS assay revealed that GLP-1RAs amended impaired cell viability induced by oxidative insult in 50B11 cells. GLP-1RAs activated superoxide dismutase. GLP-1RAs induced no alteration of the distribution pattern in neuronal markers. Ex4 rescued the cells from oxidative insult-induced apoptosis. GLP-1RAs suppressed proliferation and promoted neurite projections. No GLP-1RAs induced an accumulation of cAMP.

CONCLUSIONS

Our findings indicate that GLP-1RAs have neuroprotective potential which is achieved by their direct actions on DRG neurons. Beneficial effects of GLP-1RAs on DPN could be related to these direct actions on DRG neurons.

Hyperpolarization-activated cyclic nucleotide-gated 2 (HCN2) ion channels drive pain in mouse models of diabetic neuropathy

Diabetic patients frequently suffer from continuous pain that is poorly treated by currently available analgesics. We used mouse models of type 1 and type 2 diabetes to investigate a possible role for the hyperpolarization-activated cyclic nucleotide-gated 2 (HCN2) ion channels as drivers of diabetic pain. Blocking or genetically deleting HCN2 channels in small nociceptive neurons suppressed diabetes-associated mechanical allodynia and prevented neuronal activation of second-order neurons in the spinal cord in mice. In addition, we found that intracellular cyclic adenosine monophosphate (cAMP), a positive HCN2 modulator, is increased in somatosensory neurons in an animal model of painful diabetes. We propose that the increased intracellular cAMP drives diabetes-associated pain by facilitating HCN2 activation and consequently promoting repetitive firing in primary nociceptive nerve fibers. Our results suggest that HCN2 may be an analgesic target in the treatment of painful diabetic neuropathy.

Baseline High-Sensitivity C-Reactive Protein Predicts Macrovascular and Microvascular Complications of Type 2 Diabetes: A Population-Based Study

BACKGROUND/AIMS

This prospective study is aimed at examining the predictive value of high-sensitivity C-reactive protein (hs-CRP) for coronary heart disease (CHD) events and microvascular complications of type 2 diabetes mellitus (T2DM).

METHODS

A population-based study (NCT02958579) was conducted on 1,301 participants with T2DM (mean follow-up of 7.5 years). Risk assessment for vascular events was done at baseline, and serum hs-CRP was measured. End points of this study include CHD events, diabetic retinopathy, neuropathy, and diabetic kidney disease. Individuals with unavailable data or hs-CRP >20 mg/L were excluded. The discrimination and reclassification improvement of study end points were tested after addition of hs-CRP to traditional risk factors.

RESULTS

Median serum hs-CRP was 2.00 ranging from 0.1 to 17 mg/L. Hazards ratio of each SD increment in baseline hs-CRP was 1.028 (1.024-1.032) for CHD, 1.025 (1.021-1.029) for diabetic neuropathy, 1.037 (1.030-1.043) for diabetic retinopathy, and 1.035 (1.027-1.043) for diabetic kidney disease. The addition of hs-CRP to traditional risk factors of vascular complications of T2DM improved discrimination of all end points (p < 0.001). Net reclassification improvement ranged from 8% for diabetic neuropathy to 31% for diabetic kidney disease (p < 0.05).

CONCLUSION

Baseline hs-CRP predicts both of CHD events and microvascular complications of patients with T2D.

Factors associated with the development and severity of oxaliplatin-induced peripheral neuropathy: a systematic review

Oxaliplatin is a platinum-derivative chemotherapeutic agent used for colorectal cancer in the adjuvant and metastatic setting in combination with folinic acid and 5-fluorouracil. Oxaliplatin causes an acute cold-induced neurotoxicity and a chronic cumulative neuropathy, which can require dose modification and impact quality of life. To date, no prevention and treatment strategies have proved effective thus reinforcing the importance of identifying at-risk patients in order to maximize therapeutic benefit while minimizing neurotoxicity. Here we reviewed studies on risk and prognostic factors associated with the development and severity of oxaliplatin-induced peripheral neuropathy. A systematic search was conducted in MEDLINE and Embase, and studies investigating clinical and patient-related factors associated with oxaliplatin-induced peripheral neuropathy as their primary focus were identified, and quantitative data were extracted when available. We identified 15 studies, of which only three were prospective. Notable factors were acute neurotoxicity symptoms predicting chronic neuropathy, baseline laboratory findings, patient demographics such as age and gender, comorbidities, and environmental factors. No factor was consistently identified across multiple studies other than the association with oxaliplatin dose. Further investigation into these factors may yield insight into potential neuropathy prevention and treatment strategies.

Metformin activation of AMPK suppresses AGE-induced inflammatory response in hNSCs

A growing body of evidence suggests type 2 diabetes mellitus (T2DM) is linked to neurodegenerative diseases such as Alzheimer's disease (AD). Although the precise mechanisms remain unclear, T2DM may exacerbate neurodegenerative processes. AMP-activated protein kinase (AMPK) signaling is an evolutionary preserved pathway that is important during homeostatic energy biogenesis responses at both the cellular and whole-body levels. Metformin, a ubiquitously prescribed anti-diabetic drug, exerts its effects by AMPK activation. However, while the roles of AMPK as a metabolic mediator are generally well understood, its performance in neuroprotection and neurodegeneration are not yet well defined. Given hyperglycemia is accompanied by an accelerated rate of advanced glycosylation end product (AGE) formation, which is associated with the pathogenesis of diabetic neuronal impairment and, inflammatory response, clarification of the role of AMPK signaling in these processes is needed. Therefore, we tested the hypothesis that metformin, an AMPK activator, protects against diabetic AGE induced neuronal impairment in human neural stem cells (hNSCs). In the present study, hNSCs exposed to AGE had significantly reduced cell viability, which correlated with elevated inflammatory cytokine expression, such as IL-1α, IL-1β, IL-2, IL-6, IL-12 and TNF-α. Co-treatment with metformin significantly abrogated the AGE-mediated effects in hNSCs. In addition, metformin rescued the transcript and protein expression levels of acetyl-CoA carboxylase (ACC) and inhibitory kappa B kinase (IKK) in AGE-treated hNSCs. NF-κB is a transcription factor with a key role in the expression of a variety of genes involved in inflammatory responses, and metformin did prevent the AGE-mediated increase in NF-κB mRNA and protein levels in the hNSCs exposed to AGE. Indeed, co-treatment with metformin significantly restored inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) levels in AGE-treated hNSCs. These findings extend our understanding of the central role of AMPK in AGE induced inflammatory responses, which increase the risk of neurodegeneration in diabetic patients.