Serum tau protein as a marker of disease activity in enterohemorrhagic Escherichia coli O111-induced hemolytic uremic syndrome

Nanoparticles induced neurotoxicity

The early development of nanotechnology has spurred major interest on the toxicity of nanoparticles (NPs) due to their ability to penetrate the biological barriers such as the BBB. This review aims at addressing how silver (AgNPs), titanium dioxide (TiO2NPs), zinc oxide (ZnONPs), iron oxide (Fe3O4NPs), carbon NPs, Copper (Cu-NPs), silicon oxide (SiO2 NPs) nanoparticles and quantum dots cause neurotoxicity. Some of the major signaling that occur are the signaling related to oxidative stress, neuroinflammation, mitochondrial dysfunction and cell equilibrium, hence results in neuronal damage and neurodegeneration. It is critical to describe that there are multiple ways by how NPs may be toxic based on their size and surface, dosage, and the recipient's age and health condition. A review on in vitro and in vivo analysis provides information about the toxic potentials of NPs and preventive measures including modification of NP surface and antioxidant treatment. The results underline the necessity of comprehensive safety assessments to allow the further utilization of nanoparticles across the economy.

A novel on-a-chip system with a 3D-bioinspired gut mucus suitable to investigate bacterial endotoxins dynamics

The possible pathogenic impact of pro-inflammatory molecules produced by the gut microbiota is one of the hypotheses considered at the basis of the biomolecular dialogue governing the microbiota-gut-brain axis. Among these molecules, lipopolysaccharides (LPS) produced by Gram-negative gut microbiota strains may have a potential key role due to their toxic effects in both the gut and the brain. In this work, we engineered a new dynamic fluidic system, the MINERVA device (MI-device), with the potential to advance the current knowledge of the biological mechanisms regulating the microbiota-gut molecular crosstalk. The MI-device supported the growth of bacteria that are part of the intestinal microbiota under dynamic conditions within a 3D moving mucus model, with features comparable to the physiological conditions (storage modulus of 80 ± 19 Pa, network mesh size of 41 ± 3 nm), without affecting their viability (∼ 109 bacteria/mL). The integration of a fluidically optimized and user-friendly design with a bioinspired microenvironment enabled the sterile extraction and quantification of the LPS produced within the mucus by bacteria (from 423 ± 34 ng/mL to 1785 ± 91 ng/mL). Compatibility with commercially available Transwell-like inserts allows the user to precisely control the transport phenomena that occur between the two chambers by selecting the pore density of the insert membrane without changing the design of the system. The MI-device is able to provide the flow of sterile medium enriched with LPS directly produced by bacteria, opening up the possibility of studying the effects of bacteria-derived molecules on cells in depth, as well as the assessment and characterization of their effects in a physiological or pathological scenario.

A subarachnoid pleural fistula with massive crystal-clear pleural fluid caused by a lumbar epidural teratoma

A subarachnoid pleural fistula - a connection between the pleural cavity and the subarachnoid space - generally presents after trauma or surgery. A 1-year 11-month-old girl without a history of trauma or surgery presented with fatigue, cyanosis and dyspnoea. A chest radiograph and computed tomography (CT) demonstrated a massive pleural effusion in the right hemithorax. About 300 ml of a crystal-clear pleural effusion, which looked like pure water, was removed by insertion of a chest drain, but it continued to collect. Cisternography and CT myelography confirmed leakage of cerebral spinal fluid into the right pleural cavity around the thoracolumbar region. Magnetic resonance imaging demonstrated an 11-mm enhanced nodule in the epidural space around the right lumbar (L) 1/2 intervertebral foramen. The patient underwent surgery and epidural tumours attached to the L1 nerve root foramen were completely resected and a fistula of the dura adjacent to the tumour was sutured. Histopathological examination demonstrated a mature teratoma containing a pancreatic component. On retrospective analysis of stored pleural fluid, a raised level of pancreatic enzymes was detected. It is presumed that digestive enzymes secreted by the pancreatic component of the teratoma lysed the dura, resulting in formation of the fistula. When a crystal-clear pleural effusion is present, even in the absence of trauma or surgery, a subarachnoid pleural fistula should be considered. As far as we know, this is the first report of a subarachnoid pleural fistula caused by a paravertebral teratoma.Abbreviations: CSF: cerebrospinal fluid; CT: computed tomography; ¹¹¹In-DTPA: indium-111 diethylene triamine penta-acetic acid; MRI: magnetic resonance imaging; NIPPV: non-invasive positive pressure ventilation.

Tau, S100B and NSE as Blood Biomarkers in Acute Cerebrovascular Events

BACKGROUND/AIM

We aimed to analyze the diagnostic value of total tau (T-tau), S-100 calcium-binding protein B (S100B) and neuron-specific enolase (NSE) as blood-based biomarkers in acute ischemic stroke (AIS) or transient ischemic attack (TIA), and their correlation with symptom severity, infarct size, etiology and outcome.

PATIENTS AND METHODS

A total of 102 patients with stroke and 35 with TIA were analyzed. Subacute (63.8±50.1 h) plasma T-tau was measured with the single-molecule array (Simoa) method and NSE and S100B were evaluated for comparison. We evaluated biomarkers associations with: (i) diagnosis of AIS or TIA, (ii) cerebral infarction volume in the brain computed tomography, (iii) stroke etiology, (iv) clinical stroke severity and (iv) functional outcome after three months.

RESULTS

T-tau was higher in patients with stroke [1.0 pg/ml (IQR=0.3-2.2)] than with TIA [0.5 pg/ml (IQR=0.2-1.0), p=0.02]. The levels of S100B were also increased in stroke [0.082 μg/l (IQR=0.049-0.157)] patients compared to TIA patients [0.045 μg/l (IQR=0.03-0.073), p<0.001]. However, when the results were adjusted for confounders, significance was lost. Serum levels of NSE among patients with AIS [11.85 μg/l (IQR=9.30-16.14)] compared to those with TIA [10.96 μg/l (IQR=7.98-15.33), p=0.30] were equal. T-tau and S100B concentrations significantly correlated with cerebral infarction volume (r=0.412, p<0.001) and (r=0.597, p<0.001), also after corrections (p<0.001). mRS scores at three-month follow-up correlated with T-tau (r=0.248, p=0.016) and S100B concentrations (r=0.205, p=0.045).

CONCLUSION

For the diagnosis of TIA vs. AIS, blood T-tau and S100B concentrations discriminated only modestly. Additionally, groups were not separable after measuring of T-tau and S100B levels in the blood. T-tau and S100B concentrations correlated with the infarct size, but were not alone predictive for functional outcome at 3 months.

Serum insulin-like growth factor-binding protein 2 levels as an indicator for disease severity in enterohemorrhagic Escherichia coli induced hemolytic uremic syndrome

Background

Insulin-like growth factor-binding protein (IGFBP) 2 plays an important role in the regulation of cell adhesion, migration, growth, and apoptosis. This study aimed to investigate the clinical significance of serum IGFBP2 as a biomarker for disease activity and severity in hemolytic uremic syndrome (HUS) induced by enterohemorrhagic Escherichia coli (EHEC).

Methods

IGFBP2 production by human renal glomerular endothelial cells (RGECs) after exposure to Shiga toxin 2 (Stx-2) was investigated in vitro. Serum IGFBP2 levels in blood samples obtained from 22 patients with HUS and 10 healthy controls (HCs) were quantified using an enzyme-linked immunosorbent assay. The results were compared to the clinical features of HUS and serum tau and cytokine levels.

Results

Stx-2 induced the production of IGFBP2 in RGECs in a dose-dependent manner. Serum IGFBP2 levels were significantly higher in patients with HUS than in HCs and correlated with disease severity. Additionally, serum IGFBP2 levels were significantly higher in patients with encephalopathy than in those without encephalopathy. A serum IGFBP2 level above 3585 pg/mL was associated with a high risk of encephalopathy. Furthermore, serum IGFBP2 levels significantly correlated with serum levels of tau and inflammatory cytokines associated with the development of HUS.

Conclusions

Correlation of serum IGFBP2 level with disease activity in patients with HUS suggests that IGFBP2 may be considered as a possible indicator for disease activity and severity in HUS. Larger studies and additional experiments using various cells in central nervous system should elucidate the true value of IGFBP2 as a clinical diagnostic marker.

Abbreviations

IGFBP: insulin-like growth factor-binding protein; HUS: hemolytic uremic syndrome; EHEC: enterohemorrhagic Escherichia coli; RGECs: renal glomerular endothelial cells; STx-2: Shiga toxin 2; HCs: healthy controls; LPS: lipopolysaccharide; ROC: receiver operating characteristic; sTNFR: soluble tumor necrosis factor receptor.

Therapeutic Strategies to Protect the Central Nervous System against Shiga Toxin from Enterohemorrhagic Escherichia coli

Infection with Shiga toxin-producing Escherichia coli (STEC) may cause hemorrhagic colitis, hemolytic uremic syndrome (HUS) and encephalopathy. The mortality rate derived from HUS adds up to 5% of the cases, and up to 40% when the central nervous system (CNS) is involved. In addition to the well-known deleterious effect of Stx, the gram-negative STEC releases lipopolysaccharides (LPS) and may induce a variety of inflammatory responses when released in the gut. Common clinical signs of severe CNS injury include sensorimotor, cognitive, emotional and/or autonomic alterations. In the last few years, a number of drugs have been experimentally employed to establish the pathogenesis of, prevent or treat CNS injury by STEC. The strategies in these approaches focus on: 1) inhibition of Stx production and release by STEC, 2) inhibition of Stx bloodstream transport, 3) inhibition of Stx entry into the CNS parenchyma, 4) blockade of deleterious Stx action in neural cells, and 5) inhibition of immune system activation and CNS inflammation. Fast diagnosis of STEC infection, as well as the establishment of early CNS biomarkers of damage, may be determinants of adequate neuropharmacological treatment in time.

Pathogenic role of inflammatory response during Shiga toxin-associated hemolytic uremic syndrome (HUS)

Hemolytic uremic syndrome (HUS) is defined as a triad of noninmune microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury. The most frequent presentation is secondary to Shiga toxin (Stx)-producing Escherichia coli (STEC) infections, which is termed postdiarrheal, epidemiologic or Stx-HUS, considering that Stx is the necessary etiological factor. After ingestion, STEC colonize the intestine and produce Stx, which translocates across the intestinal epithelium. Once Stx enters the bloodstream, it interacts with renal endothelial and epithelial cells, and leukocytes. This review summarizes the current evidence about the involvement of inflammatory components as central pathogenic factors that could determine outcome of STEC infections. Intestinal inflammation may favor epithelial leakage and subsequent passage of Stx to the systemic circulation. Vascular damage triggered by Stx promotes not only release of thrombin and increased fibrin concentration but also production of cytokines and chemokines by endothelial cells. Recent evidence from animal models and patients strongly indicate that several immune cells types may participate in HUS physiopathology: neutrophils, through release of proteases and reactive oxygen species (ROS); monocytes/macrophages through secretion of cytokines and chemokines. In addition, high levels of Bb factor and soluble C5b-9 (sC5b-9) in plasma as well as complement factors adhered to platelet-leukocyte complexes, microparticles and microvesicles, suggest activation of the alternative pathway of complement. Thus, acute immune response secondary to STEC infection, the Stx stimulatory effect on different immune cells, and inflammatory stimulus secondary to endothelial damage all together converge to define a strong inflammatory status that worsens Stx toxicity and disease.

Cerebral Hemodynamics in Patients with Hemolytic Uremic Syndrome Assessed by Susceptibility Weighted Imaging and Four-Dimensional Non-Contrast MR Angiography

Background and Purpose

Conventional magnetic resonance imaging (MRI) of patients with hemolytic uremic syndrome (HUS) and neurological symptoms performed during an epidemic outbreak of Escherichia coli O104:H4 in Northern Europe has previously shown pathological changes in only approximately 50% of patients. In contrast, susceptibility-weighted imaging (SWI) revealed a loss of venous contrast in a large number of patients. We hypothesized that this observation may be due to an increase in cerebral blood flow (CBF) and aimed to identify a plausible cause.

Materials and Methods

Baseline 1.5T MRI scans of 36 patients (female, 26; male, 10; mean age, 38.2±19.3 years) were evaluated. Venous contrast was rated on standard SWI minimum intensity projections. A prototype four-dimensional (time resolved) magnetic resonance angiography (4D MRA) assessed cerebral hemodynamics by global time-to-peak (TTP), as a surrogate marker for CBF. Clinical parameters studied were hemoglobin, hematocrit, creatinine, urea levels, blood pressure, heart rate, and end-tidal CO₂.

Results

SWI venous contrast was abnormally low in 33 of 36 patients. TTP ranged from 3.7 to 10.2 frames (mean, 7.9 ± 1.4). Hemoglobin at the time of MRI (n = 35) was decreased in all patients (range, 5.0 to 12.6 g/dL; mean, 8.2 ± 1.4); hematocrit (n = 33) was abnormally low in all but a single patient (range, 14.3 to 37.2%; mean, 23.7 ± 4.2). Creatinine was abnormally high in 30 of 36 patients (83%) (range, 0.8 to 9.7; mean, 3.7 ± 2.2). SWI venous contrast correlated significantly with hemoglobin (r = 0.52, P = 0.0015), hematocrit (r = 0.65, P < 0.001), and TTP (r = 0.35, P = 0.036). No correlation of SWI with blood pressure, heart rate, end-tidal CO₂, creatinine, and urea level was observed. Findings suggest that the loss of venous contrast is related to an increase in CBF secondary to severe anemia related to HUS. SWI contrast of patients with pathological conventional MRI findings was significantly lower compared to patients with normal MRI (mean SWI score, 1.41 and 2.05, respectively; P = 0.04). In patients with abnormal conventional MRI, mean TTP (7.45), mean hemoglobin (7.65), and mean hematocrit (22.0) were lower compared to patients with normal conventional MRI scans (mean TTP = 8.28, mean hemoglobin = 8.63, mean hematocrit = 25.23).

Conclusion

In contrast to conventional MRI, almost all patients showed pathological changes in cerebral hemodynamics assessed by SWI and 4D MRA. Loss of venous contrast on SWI is most likely the result of an increase in CBF and may be related to the acute onset of anemia. Future studies will be needed to assess a possible therapeutic effect of blood transfusions in patients with HUS and neurological symptoms.

Tumor necrosis factor-α modifies the effects of Shiga toxin on glial cells

Shiga toxin (STX) is one of the main factors inducing hemorrhagic colitis and hemolytic-uremic syndrome (HUS) in infections with STX-producing Escherichia coli (STEC). Approximately 62% of patients with HUS showed symptoms of encephalopathy in the 2011 Japanese outbreak of STEC infections. At that time, we reported elevated serum concentrations of tumor necrosis factor (TNF)-α in patients with acute encephalopathy during the HUS phase. In the current study, we investigated whether TNF-α augments the effects of STX in glial cell lines and primary glial cells. We found that TNF-α alone or STX in combination with TNF-α activates nuclear factor-κB (NF-κB) signaling and inhibits growth of glial cells. The magnitude of the NF-κB activation and the inhibition of cell growth by the STX and TNF-α combination was greater than that obtained with TNF-α alone or STX alone. Thus, this in vitro study reveals the role of TNF-α in glial cells during STEC infections.

The critical role of lipopolysaccharide in the upregulation of aquaporin 4 in glial cells treated with Shiga toxin

Background

In 2011, there was an outbreak of Shiga toxin-producing Escherichia coli (STEC) infections in Japan. Approximately 62 % of patients with hemolytic-uremic syndrome also showed symptoms of encephalopathy. To determine the mechanisms of onset for encephalopathy during STEC infections, we conducted an in vitro study with glial cell lines and primary glial cells.

Results

Shiga toxin 2 (Stx-2) in combination with lipopolysaccharide (LPS), or LPS alone activates nuclear factor-κB (NF-κB) signaling in glial cells. Similarly, Stx-2 in combination with LPS, or LPS alone increases expression levels of aquaporin 4 (AQP4) in glial cells. It is possible that overexpression of AQP4 results in a rapid and increased influx of osmotic water across the plasma membrane into cells, thereby inducing cell swelling and cerebral edema.

Conclusions

We have showed that a combination of Stx-2 and LPS induced apoptosis of glial cells recently. Glial cells are indispensable for cerebral homeostasis; therefore, their dysfunction and death impairs cerebral homeostasis and results in encephalopathy. We postulate that the onset of encephalopathy in STEC infections occurs when Stx-2 attacks vascular endothelial cells of the blood–brain barrier, inducing their death. Stx-2 and LPS then attack the exposed glial cells that are no longer in contact with the endothelial cells. AQP4 is overexpressed in glial cells, resulting in their swelling and adversely affecting cerebral homeostasis. Once cerebral homeostasis is affected in such a way, encephalopathy is the likely result in STEC patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s12929-015-0184-5) contains supplementary material, which is available to authorized users.