S100B as a glial cell marker in diabetic peripheral neuropathy

Colloidal gold-based immunochromatographic biosensor for quantitative detection of S100B in serum samples

Traumatic brain injury has become a serious public health problem. Timely detection, diagnosis and treatment of brain injury are closely related to the prognosis of patients, so identification of highly sensitive and specific biochemical markers of brain injury has important clinical value. Currently, the most studied and most promising marker is the protein S100B. In this study, a rapid quantitative biosensor for S100B was established using colloidal gold labeling and double antibody (8C10-6B8) sandwich immunochromatography. The biosensor was capable of quantifying S100B within 15 min, and showed no cross-reactivity with S100A, NSE, GFAP, or PGP9.5. The detection limit was determined to be 4.6 pg mL-1 with a linear range of 0.01-2 ng mL-1. Recovery experiments also indicated that the method had an acceptable accuracy. Moreover, the quantitative colloidal gold assay correlated well with the results of a chemiluminescence immunoassay when testing 40 clinical serum samples. Our developed colloidal gold quantitative immunochromatographic biosensor is a rapid, sensitive, specific and accurate method for the detection of S100B protein in serum, which is useful in the clinic for early diagnosis, as well as assessment of disease progression and prognosis of traumatic brain injury.

The receptor for advanced glycation end products and its ligands' expression in OVE26 diabetic sciatic nerve during the development of length-dependent neuropathy

Type 1 diabetes (T1D) may affect the peripheral nervous system and alter the expression of proteins contributing to inflammation and cellular cytoskeleton dysfunction, in most cases leading to the development of diabetic length-dependent neuropathy (DLDN). In the present study, we performed immunohistochemistry (IHC) to probe the expression of the receptor for advanced glycation end products (RAGE); its key ligands, high-mobility group box 1 (HMGB1), S100 calcium-binding protein B (S100B), and carboxymethyl-lysine (CML - advanced glycation end products (AGE)); and its cytoplasmic tail-binding partner, diaphanous related formin 1 (DIAPH1) and associated molecules, beta-actin (ACTB) and profilin 1 (PFN1) proteins in sciatic nerves harvested from seven-month old FVB/OVE26 mice with genetically-mediated T1D. We found that the amount of RAGE, HMGB1, and S100B proteins was elevated in diabetic vs the non-diabetic groups, while the amount of DIAPH1, ACTB, as well as PFN1 proteins did not differ between these groups. Moreover, our data revealed linear dependence between RAGE and HMGB1 proteins. Interaction criss-cross of selected sets of proteins in the sciatic nerve revealed that there were connected in a singular network. Our results indicate that T1D may alter expression patterns of RAGE axis proteins and thus contribute to DLDN.

Types and Concentrations of Blood-Based Biomarkers in Adults With Peripheral Neuropathies: A Systematic Review and Meta-analysis

Importance

Peripheral neuropathies are common conditions and can result in numbness, paresthesia, motor deficits, and pain. There is increasing evidence for the use of biomarkers as clinical indicators of the presence, severity, and prognosis of nerve lesions; however, biomarker identification has largely been focused on disorders of the central nervous system, and less is known about their role in the peripheral nervous system.

Objective

To assess blood-based biomarker concentrations associated with nerve involvement in patients with peripheral neuropathy compared with control participants.

Data Sources

Ovid, MEDLINE, Embase, and CINAHL were searched from inception to September 23, 2021.

Study Selection

Observational studies reporting on blood biomarkers in patients diagnosed with peripheral neuropathy were included. This review was preregistered on PROSPERO and followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guideline. Data were abstracted by 1 investigator and independently reviewed by a second.

Data Extraction and Synthesis

Data were meta-analyzed when at least 2 studies reported the same biomarker with comparable methodology. Fixed-effects models were used when only 2 studies were included; random-effects models were used when more than 2 studies were included.

Main Outcomes and Measures

The outcome of interest was concentration of biomarkers.

Results

This review included 36 studies reporting on 4414 participants, including 2113 control participants and 2301 patients with peripheral neuropathy with 13 distinct peripheral neuropathy diagnoses. Diabetic neuropathy was the most common neuropathy diagnosis (13 studies), followed by Charcot-Marie-Tooth disease (6 studies) and Guillain-Barre syndrome (6 studies). Overall, 16 different blood-based biomarkers associated with nerve involvement were evaluated. The most used were neurofilament light chain, S100B, brain-derived neurotrophic factor, and neuron-specific enolase. Patients with peripheral neuropathy demonstrated significantly higher levels of neurofilament light chain compared with controls (standardized mean difference [SMD], 0.93 [95% CI, 0.82 to 1.05]; P < .001). There were no significant differences in levels of S100B (SMD, 1.10 [95% CI, -3.08 to 5.28]; P = .38), brain-derived neurotrophic factor (SMD, -0.52 [95% CI, -2.23 to 1.19]; P = .40), or neuron-specific enolase (SMD, -0.00 [95% CI, -1.99 to 1.98]; P = .10) in patients with peripheral neuropathy compared with control participants.

Conclusions and Relevance

The findings of this systematic review and meta-analysis support the use of neurofilament light chain as a blood-based measure associated with the presence of neuronal injury in patients with peripheral neuropathy.

Plasma biomarkers of brain injury in COVID-19 patients with neurological symptoms

Objective

Neurological symptoms (NS) were often reported in COVID-19 infection. We examined the plasma levels of glial fibrillary acidic protein (GFAP) and S100B together, as brain injury biomarkers, in relation to persistent NS in a cohort of patients with COVID-19 during the acute phase of the disease.

Methods

A total of 20 healthy controls and 58 patients with confirmed COVID-19 were enrolled in this prospective study. Serum GFAP and S100B levels were measured by using enzymle linked immunoassay method from blood samples.

Results

Serum GFAP levels were found to be significantly higher in the severe group than in the controls (p = 0.007). However, serum S100B levels were similar between control and disease groups (p > 0.05). No significant results for GFAP and S100B were obtained between the disease groups depending on whether the sampling time was below or above 5 days (p > 0.05). We did not find a correlation between serum GFAP and S100B levels and the presence of NS (p > 0.05). However, serum S100B levels were slightly higher in patients with multiple NS than in those with a single symptom (p = 0.044).

Conclusions

Elevated GFAP was associated with disease severity but not with NS in COVID-19 patients. Whereas, high serum S100B was associated with the multipl NS in these patients. Our data suggest that GFAP and S100B may be of limited value currently in order to represent the neuronal damage, though serving a basis for the future work.

The cross-talk between RAGE and DIAPH1 in neurological complications of diabetes: A review

Neuropathy, or dysfunction of peripheral nerve, is one of the most common neurological manifestation in patients with diabetes mellitus (DM). DM is typically associated with a hyperglycaemic milieu, which promotes non-enzymatic glycation of proteins. Proteins with advanced glycation are known to engage a cell-surface receptor called the receptor for advanced glycation end products (RAGE). Thus, it is reasonable to assume that RAGE and its associated molecule-mediated cellular signalling may contribute to DM-induced symmetrical axonal (length-dependent) neuropathy. Of particular interest is diaphanous related formin 1 (DIAPH1), a cytoskeletal organizing molecule, which interacts with the cytosolic domain of RAGE and whose dysfunction may precipitate axonopathy/neuropathy. Indeed, it has been demonstrated that both RAGE and DIAPH1 are expressed in the motor and sensory fibres of nerve harvested from DM animal models. Although the detailed molecular role of RAGE and DIAPH1 in diabetic neurological complications remains unclear, here we will discuss available evidence of their involvement in peripheral diabetic neuropathy. Specifically, we will discuss how a hyperglycaemic environment is not only likely to elevate advanced glycation end products (ligands of RAGE) and induce a pro-inflammatory environment but also alter signalling via RAGE and DIAPH1. Further, hyperglycaemia may regulate epigenetic mechanisms that interacts with RAGE signalling. We suggest the cumulative effect of hyperglycaemia on RAGE-DIAPH1-mediated signalling may be disruptive to axonal cytoskeletal organization and transport and is therefore likely to play a key role in pathogenesis of diabetic symmetrical axonal neuropathy.

Circulating Level of Myelin Basic Protein Predicts Postherpetic Neuralgia: A Prospective Study

OBJECTIVES

Patients with herpes zoster (HZ) would benefit from accurate prediction of whether they are likely to develop postherpetic neuralgia (PHN). We investigated whether a circulating biomarker of neuronal damage could be a predictor of PHN in this nonmatched prospective, nested, case-control study.

MATERIALS AND METHODS

We included patients with HZ who were within 90 days after rash onset. Volunteers without a history of HZ were recruited as controls. We evaluated epidemiologic factors and circulating neuronal damage biomarkers, including cell-free DNA, myelin basic protein (MBP), and soluble protein-100B (S100B). We conducted logistic regression analyses to develop a prediction model of PHN.

RESULTS

We found that cell-free DNA and MBP levels were higher in patients with HZ (n=71) than in controls (n=37). However, only MBP level was higher in patients who developed PHN (n=25), in comparison with those who did not (n=46). MBP level and 3 clinical factors, age, acute pain severity, and response to treatment drugs were identified as independent predictors of PHN. Receiver operating characteristic (ROC) curve analysis showed that the prediction made using a combination of MBP level and clinical factors had an area under ROC curve of 0.853 (95% confidence interval: 0.764 to 0.943), which was better than prediction using clinical factors alone (area under ROC curve: 0.823, 95% confidence interval: 0.728 to 0.917).

DISCUSSION

Our results indicate that circulating MBP level in patients with HZ is a predictor for PHN. The combination of clinical predictors and MBP level enhanced the prediction performance.

Sensitively detecting mTBI biomarker S100B by using peptide-modified ratiometric fluorescent C/AuNCs nanoprobe

Mild traumatic brain injury (mTBI) has become a tough nut in forensic science because of its minor damages but serious consequences. Utilizing biomarkers to diagnose mTBI has become a promising approach due to various shortcomings of traditional diagnostic methods. In this work, we developed a peptide-modified ratiometric fluorescent nanoprobe based on carbon dots (CDs) and gold nanoclusters (AuNCs) for the measurements of a pivotal biomarker S100B protein in the early diagnosis of mTBI. It has been found that florescence intensity of AuNCs at 580 nm was decreased as report signal while the florescence intensity of CDs was unchanged as reference signal in this sensing system when the surface modified peptide bind tightly with calcium-activated S100B. Under the optimized conditions, S100B concentration ranging from 0.03 to 1 μg/mL was successfully determined within 30 min, and the detection limit of 0.01 μg/mL was acquired through the standard rule (S/N = 3). Moreover, the detection of S100B in spiked blood samples were conducted with satisfactory recoveries. The as-prepared ratiometric fluorescent nanoprobe was proved to be a time-saving, convenient, and sensitive strategy, and it showed great prospects in the early diagnosis of mTBI in forensic practice.

Levels of serum S100B are associated with cognitive dysfunction in patients with type 2 diabetes

Objective: Previous studies have provided robust evidence that cognitive impairment exists in patients with type 2 diabetes. The predictive role of S100B in a variety of neurodegenerative diseases such as Alzheimer’s disease, has been shown to be closely related to cognitive function. The purpose of this study was to investigate the correlation between serum S100B levels and cognitive function in type 2 diabetes patients.

Results: The type 2 diabetes group scored lower than the healthy control group in all domains of cognitive function except language and attention, and the former group also had lower serum levels of S100B. Besides, serum S100B levels were lower in the type 2 diabetes patients with impaired cognition than in those with normal cognition. In addition, the moderate to severe cognitive impairment group had significantly lower levels than that in mild cognitive impairment group. After adjusting for confounding factors, serum S100B levels were positively correlated with cognitive function in type 2 diabetes patients.

Conclusions: Serum S100B levels were positively correlated with cognitive function in type 2 diabetes patients with cognitive impairment. It is suggested that S100B may be involved in the occurrence and development of cognitive dysfunction in type 2 diabetes patients and play a protective role.

Methods: The clinical data and biochemical indexes of ninety-six patients with type 2 diabetes and sixty-eight healthy subjects were collected. The levels of serum S100B were detected by enzyme-linked immunosorbent assay. Ninety-six type 2 diabetes patients were divided into a cognitive dysfunction group and a normal cognition group according to Mini-mental State Examination scores. To better understand the differences in various aspects of cognition, we used the Repeatable Battery for the Assessment of Neuropsychological Status scale for further evaluation. To study the relationship between serum S100B levels and cognitive impairment, the cognitive dysfunction group was divided into a mild cognitive impairment group and a moderate to severe cognitive impairment group for further study.

Assessment of neuron-specific enolase, S100B and malondialdehyde levels in serum and vitreous of patients with proliferative diabetic retinopathy

PURPOSE

To assess the vitreous and serum levels of neuron-specific enolase (NSE), S100B and malondialdehyde (MDA) in proliferative diabetic retinopathy (PDR) cases and investigate the correlation between preoperative and postoperative anatomical and clinical features.

MATERIALS AND METHODS

The study group included patients who had pars plana vitrectomy (PPV) for PDR. The control group included non-diabetic individuals who underwent PPV surgery for vitreoretinal interface disorders. Samples of serum were taken from all participants preoperatively, while vitreous samples were taken during the PPV. Vitreous and serum levels of NSE, S100B and MDA were measured, and comparisons were made between the groups.

RESULTS

The study group consisted of 56 eyes of 56 cases with PDR. The control group consisted of 20 eyes of 20 cases. The concentrations of vitreous NSE, S100B and MDA were significantly higher than the control group (p < 0.0001, p < 0.05, p < 0.001, respectively). Serum levels were statistically different for NSE and S100B (p < 0.05).

CONCLUSION

Our results clearly show that vitreous levels of S100B, NSE and MDA and serum concentrations of NSE and S100B increased significantly in patients with PDR. The findings may possibly indicate neurodegeneration and oxidative stress; therefore, these markers may have a diagnostic value in patients with PDR.

Associations of Serum S100B and S100P With the Presence and Classification of Diabetic Peripheral Neuropathy in Adults With Type 2 Diabetes: A Case-Cohort Study

OBJECTIVES

Novel biomarkers of diabetic peripheral neuropathy provide potentially useful information for early identification and treatment of diabetic neuropathy, ultimately serving to reduce the burden of disease. This study was designed to investigate the potential associations of serum S100B and S100P (calcium-modulated proteins) with the presence and classification of diabetic peripheral neuropathy in adults with type 2 diabetes.

METHODS

In a case-cohort setting, the data of 44 participants diagnosed with diabetic peripheral neuropathy, 44 control participants with type 2 diabetes but free of peripheral neuropathy and 87 healthy control individuals were collected and analyzed.

RESULTS

Serum S100P concentrations were elevated in participants with diabetic peripheral neuropathy compared with their controls with type 2 diabetes (median [IQR]: 2,235 pg/mL [1,497.5 to 2,680] vs. 1,200 pg/mL [975 to 1,350)], respectively; p<0.001). Conversely, serum S100B values were comparable in these 2 groups (p=0.570). Those with the typical diabetic peripheral neuropathy had significantly higher serum S100P levels compared to their counterparts with the atypical group of diabetic peripheral neuropathies (p=0.048). The independent significant association between serum S100P and diabetic peripheral neuropathy persisted into the multivariable adjusted logistic regression model (OR for S100P: 1.004 [95% CI 1.002 to 1.006]; p<0.001).

CONCLUSIONS

The present study's findings demonstrated that serum S100P is a more significant indicator of peripheral neuropathy in type 2 diabetes than is serum S100B. Prospective longitudinal studies are required to confirm the prognostic value of baseline serum S100P to predict incident peripheral neuropathy in people with diabetes.

Towards frailty biomarkers: Candidates from genes and pathways regulated in aging and age-related diseases

OBJECTIVE

Use of the frailty index to measure an accumulation of deficits has been proven a valuable method for identifying elderly people at risk for increased vulnerability, disease, injury, and mortality. However, complementary molecular frailty biomarkers or ideally biomarker panels have not yet been identified. We conducted a systematic search to identify biomarker candidates for a frailty biomarker panel.

METHODS

Gene expression databases were searched (http://genomics.senescence.info/genes including GenAge, AnAge, LongevityMap, CellAge, DrugAge, Digital Aging Atlas) to identify genes regulated in aging, longevity, and age-related diseases with a focus on secreted factors or molecules detectable in body fluids as potential frailty biomarkers. Factors broadly expressed, related to several "hallmark of aging" pathways as well as used or predicted as biomarkers in other disease settings, particularly age-related pathologies, were identified. This set of biomarkers was further expanded according to the expertise and experience of the authors. In the next step, biomarkers were assigned to six "hallmark of aging" pathways, namely (1) inflammation, (2) mitochondria and apoptosis, (3) calcium homeostasis, (4) fibrosis, (5) NMJ (neuromuscular junction) and neurons, (6) cytoskeleton and hormones, or (7) other principles and an extensive literature search was performed for each candidate to explore their potential and priority as frailty biomarkers.

RESULTS

A total of 44 markers were evaluated in the seven categories listed above, and 19 were awarded a high priority score, 22 identified as medium priority and three were low priority. In each category high and medium priority markers were identified.

CONCLUSION

Biomarker panels for frailty would be of high value and better than single markers. Based on our search we would propose a core panel of frailty biomarkers consisting of (1) CXCL10 (C-X-C motif chemokine ligand 10), IL-6 (interleukin 6), CX3CL1 (C-X3-C motif chemokine ligand 1), (2) GDF15 (growth differentiation factor 15), FNDC5 (fibronectin type III domain containing 5), vimentin (VIM), (3) regucalcin (RGN/SMP30), calreticulin, (4) PLAU (plasminogen activator, urokinase), AGT (angiotensinogen), (5) BDNF (brain derived neurotrophic factor), progranulin (PGRN), (6) α-klotho (KL), FGF23 (fibroblast growth factor 23), FGF21, leptin (LEP), (7) miRNA (micro Ribonucleic acid) panel (to be further defined), AHCY (adenosylhomocysteinase) and KRT18 (keratin 18). An expanded panel would also include (1) pentraxin (PTX3), sVCAM/ICAM (soluble vascular cell adhesion molecule 1/Intercellular adhesion molecule 1), defensin α, (2) APP (amyloid beta precursor protein), LDH (lactate dehydrogenase), (3) S100B (S100 calcium binding protein B), (4) TGFβ (transforming growth factor beta), PAI-1 (plasminogen activator inhibitor 1), TGM2 (transglutaminase 2), (5) sRAGE (soluble receptor for advanced glycosylation end products), HMGB1 (high mobility group box 1), C3/C1Q (complement factor 3/1Q), ST2 (Interleukin 1 receptor like 1), agrin (AGRN), (6) IGF-1 (insulin-like growth factor 1), resistin (RETN), adiponectin (ADIPOQ), ghrelin (GHRL), growth hormone (GH), (7) microparticle panel (to be further defined), GpnmB (glycoprotein nonmetastatic melanoma protein B) and lactoferrin (LTF). We believe that these predicted panels need to be experimentally explored in animal models and frail cohorts in order to ascertain their diagnostic, prognostic and therapeutic potential.

Deficiency of S100B confers resistance to experimental diabetes in mice

The calcium binding protein S100B has been implicated in diabetic neuronal and vascular complications but has not been examined in the development of diabetes. S100B knock out (S100B KO) and wild-type (WT) mice were injected with 40 mg/kg body weight streptozotocin (STZ) for 5 days. Blood and pancreatic tissue samples were obtained to examine islet structure and function, the profile of glucose and insulin and expression of glucose transporter 2 (Glut2), S100B and its receptor, the receptor for advanced glycation end products (RAGE). Primary islet β-cells cultures from WT mice were used to test the apoptotic potential of S100B. S100B KO mice were resistant to STZ induced-diabetes with lower urine volume, food and water intake compared to WT mice. S100B increased in the WT islet following diabetes but did not co-localize with beta or peri-islet Schwann cells but with CD3 + T lymphocytes. S100B KO mice exhibited enhanced glucose tolerance, insulin sensitivity, prevented β-cell destruction and functional impairment in response to STZ treatment. S100B deficiency was associated with decreased Glut2 and RAGE. In primary β-cell cultures from WT mice, S100B induced reactive oxygen species (ROS) and RAGE-dependent apoptosis. In the STZ diabetic animal model, abrogation of S100B enhances insulin sensitivity and reduces pancreatic islet, and β-cell destruction. S100B may be a promising target for pharmacological interventions aimed at repressing diabetes.

S100B Levels in Patients with Type 2 Diabetes Mellitus and Co-Occurring Depressive Symptoms

Depression is a comorbid condition in patients with Type 2 Diabetes mellitus (T2DM). S100B, a glia derived protein, is linked to depression and has been suggested as a biomarker for depression outcomes in several populations. However, to date there is no data about S100B levels and depression in patients with T2DM. Objective. We hypothesized that S100B serum levels are increased in patients with T2DM and recently diagnosed, drug-free depressive symptoms, and could be used for the diagnosis of depression in T2DM. Methods. Overall 52 patients (62 ± 12 years, female 66, 7%) with no history of depression deriving from the Diabetes out-patient clinic of our University Hospital underwent a one-to-one interview with a psychiatrist and filled a self-assessment (Zung) questionnaire. Serum S00B levels were compared between 30 (63±12 years, female 66, 7%) diabetic patients without depressive symptoms vs 22 patients (62 ±12 years, female 68, 2%) with T2DM and depressive symptoms. Results. There was no difference in serum levels of S100B between patients with T2DM without depressive symptoms vs diabetic patients suffering from depressive symptoms (2.1 (1.9-10.9) pg/ml vs 2.4 (1.9-14.8) pg/ml, p=0. 637+). Moreover, linear regression analysis did not show any association between lnS100B levels and depressive symptoms (β = 0.084, 95% CI 0.470-0.871, and p=0.552), Zung self-assessment score (β = 0.048, 95% CI -0.024-0.033, and p=0.738), and other patients' characteristics. Conclusions. In patients with T2DM there is no correlation between S100B serum levels and newly detected mild depressive symptoms. The brain biochemistry pathways of depression in T2DM warrant further investigation in a larger scale population.

Down-regulation of S100A1 protein in patients with metabolic syndrome and its association with zinc-α2-glycoprotein

Objectives It has been proposed that zinc-α2-glycoprotein and S100A1 are possibly linked to the development of lipogenesis and obesity. We aimed to measure serum levels of S100A1 and zinc-α2-glycoprotein in patients with metabolic syndrome and investigate any associations of these two novel peptides with each other or components of metabolic syndrome. Methods Forty-four patients with metabolic syndrome and the equivalent number of healthy controls participated in this study. The participants' body mass index, waist circumference, systolic and diastolic blood pressure were measured. Serum levels of low- and high-density lipoprotein cholesterol, total cholesterol, triglyceride, fasting blood sugar, insulin, zinc-α2-glycoprotein and S100A1 protein were determined. Results Higher levels of anthropometric and lipid indices, metabolic factors and also SBP and DBP were observed in the metabolic syndrome group. Serum S100A1 levels were significantly lower in the metabolic syndrome group than the control group ( P = 0.008). There was a strong positive correlation between serum zinc-α2-glycoprotein and S100A1 levels ( r = 0.80, P < 0.0001). Serum levels of both S100A1 ( P = 0.03) and zinc-α2-glycoprotein ( P = 0.02) were potentially higher in subjects with hypertension than those with normal blood pressure, though these were found as part of multiple testing. Conclusion The results indicate that changes in the circulating level of S100A1 protein occur in metabolic syndrome patients. The strong correlation between serum zinc-α2-glycoprotein and S100A1 might suggest that production or release of these two proteins could be related mechanistically.

ALCAM a novel biomarker in patients with type 2 diabetes mellitus complicated with diabetic nephropathy

BACKGROUND & AIM

Activated leukocyte cell adhesion molecule (ALCAM/CD166) functions analogue to the receptor of advanced glycation end products, which has been implicated in the development of diabetic nephropathy (DN). We investigated the expression of ALCAM and its ligand S100B in patients with DN.

METHODS

A total of 34 non-diabetic patients, 29 patients with type 2 diabetes and normal albuminuria and 107 patients with type 2 diabetes complicated with DN were assessed for serum concentration of soluble ALCAM (sALCAM) by ELISA. Expression of ALCAM and S100B in kidney histology from patients with DN was determined by immunohistochemistry. Cell expression of ALCAM and S100B was analyzed through confocal immunofluorescence microscopy.

RESULTS

Serum concentration of sALCAM was increased in diabetic patients with DN compared to non-diabetic (59.85±14.99ng/ml vs. 126.88±66.45ng/ml, P<0.0001). Moreover sALCAM correlated positively with HbA1c (R=0.31, P<0.0001), as well as with the stages of chronic kidney disease and negatively correlated with eGFR (R=-0.20, P<0.05). In diabetic patients with normal albuminuria sALCAM was increased compared to patients with DN (126.88±66.45ng/ml vs. 197.50±37.17ng/ml, P<0.0001). In diabetic patients, ALCAM expression was significantly upregulated in both the glomeruli and tubules (P<0.001). ALCAM expression in the glomeruli correlated with presence of sclerosis (R=0.25, P<0.001) and localized mainly in the podocytes supporting the hypothesis that membrane bound ALCAM drives diabetic nephropathy and thus explaining sALCAM decrease in diabetic patients with DN. The expression of S100B was increased significantly in the glomeruli of diabetic patients (P<0.001), but not in the tubules. S100B was as well localized in the podocytes.

CONCLUSIONS

This study identifies for the first time ALCAM as a potential mediator in the late complications of diabetes in the kidney.

Peripheral Levels of AGEs and Astrocyte Alterations in the Hippocampus of STZ-Diabetic Rats

Diabetic patients and streptozotocin (STZ)-induced diabetes mellitus (DM) models exhibit signals of brain dysfunction, evidenced by neuronal damage and memory impairment. Astrocytes surrounding capillaries and synapses modulate many brain activities that are connected to neuronal function, such as nutrient flux and glutamatergic neurotransmission. As such, cognitive changes observed in diabetic patients and experimental models could be related to astroglial alterations. Herein, we investigate specific astrocyte changes in the rat hippocampus in a model of DM induced by STZ, particularly looking at glial fibrillary acidic protein (GFAP), S100B protein and glutamate uptake, as well as the content of advanced glycated end products (AGEs) in serum and cerebrospinal fluid (CSF), as a consequence of elevated hyperglycemia and the content of receptor for AGEs in the hippocampus. We found clear peripheral alterations, including hyperglycemia, low levels of proinsulin C-peptide, elevated levels of AGEs in serum and CSF, as well as an increase in RAGE in hippocampal tissue. We found specific astroglial abnormalities in this brain region, such as reduced S100B content, reduced glutamate uptake and increased S100B secretion, which were not accompanied by changes in GFAP. We also observed an increase in the glucose transporter, GLUT-1. All these changes may result from RAGE-induced inflammation; these astroglial alterations together with the reduced content of GluN1, a subunit of the NMDA receptor, in the hippocampus may be associated with the impairment of glutamatergic communication in diabetic rats. These findings contribute to understanding the cognitive deficits in diabetic patients and experimental models.

Intracerebral Glycine Administration Impairs Energy and Redox Homeostasis and Induces Glial Reactivity in Cerebral Cortex of Newborn Rats

Accumulation of glycine (GLY) is the biochemical hallmark of glycine encephalopathy (GE), an aminoacidopathy characterized by severe neurological dysfunction that may lead to early death. In the present study, we evaluated the effect of a single intracerebroventricular administration of GLY on bioenergetics, redox homeostasis, and histopathology in brain of neonatal rats. Our results demonstrated that GLY decreased the activities of the respiratory chain complex IV and creatine kinase, induced reactive species generation, and diminished glutathione (GSH) levels 1, 5, and 10 days after GLY injection in cerebral cortex of 1-day-old rats. GLY also increased malondialdehyde (MDA) levels 5 days after GLY infusion in this brain region. Furthermore, GLY differentially modulated the activities of superoxide dismutase, catalase, and glutathione peroxidase depending on the period tested after GLY administration. In contrast, bioenergetics and redox parameters were not altered in brain of 5-day-old rats. Regarding the histopathological analysis, GLY increased S100β staining in cerebral cortex and striatum, and GFAP in corpus callosum of 1-day-old rats 5 days after injection. Finally, we verified that melatonin prevented the decrease of complex IV and CK activities and GSH concentrations, and the increase of MDA levels and S100β staining caused by GLY. Based on our findings, it may be presumed that impairment of redox and energy homeostasis and glial reactivity induced by GLY may contribute to the neurological dysfunction observed in GE.