Diagnosis and treatment of early renal disease in patients with type 2 diabetes mellitus: what are the clinical needs?

Renal disease is prevalent in patients with diabetes mellitus type 2. Aggressive metabolic control and lowering of systemic and/or intraglomerular blood pressure are effective interventions but not without side effects. Thus a better, early identification of patients at risk for incidence or progression to end-stage renal failure by the use of new, validated biomarkers is highly desirable. In the majority of patients, hypertension and hyperglycaemia are pathogenetically important pathways for the progression of renal disease. Nonetheless even aggressive therapy targeting these factors does not eliminate the risk of end-stage renal failure and experimental evidence suggests that many other pathways (e.g. tubulointerstitial hypoxia or inflammation etc.) also contribute. As their individual importance might vary from patient to patient, interventions which interfere are likely not to be therapeutically effective in all subjects. In this situation, an option to preserve the statistical power of clinical trials is to rely on biomarkers that reflect individual pathophysiology. In current clinical practice, albuminuria is the biomarker that has been best evaluated to guide stratified/personalized therapy but there is a clear need to expand our diagnostic abilities.

When the endothelium scores an own goal: endothelial cells actively augment metastatic extravasation through endothelial-mesenchymal transition

Endothelial-mesenchymal transition (EndMT) is an important mechanism during organ development and in certain pathological conditions. For example, EndMT contributes to myofibroblast formation during organ fibrosis, and it has been identified as an important source of cancer-associated fibroblasts, facilitating tumor progression. Recently, EndMT was proposed to modulate endothelial function during intravasation and extravasation of metastatic tumor cells. Evidence suggests that endothelial cells are not passive actors during transendothelial migration (TEM) of cancer cells, as there are profound changes in endothelial junctional protein expression, signaling, permeability, and contractility. This review describes these alterations in endothelial characteristics during TEM of metastatic tumor cells and discusses them in the context of EndMT. EndMT could play an important role during metastatic intravasation and extravasation, a novel hypothesis that may lead to new therapeutic approaches to tackle metastatic disease.

Expression of Vascular Endothelial Growth Factor Has a Regulatory Role in Gingival Venules in Experimental Diabetes

BACKGROUND

In the present study, the possible localization and role of vascular endothelial growth factor receptor type 2 (VEGFR2) in the regulation of gingival venules in a rat model of experimental diabetes are examined.

METHODS

Six weeks after streptozotocin premedication, Wistar male rats presenting blood sugar levels >20 mmol/L were selected for investigation. The VEGFR2 antagonist ZM323881 [5-((7-benzyloxyquinazolin-4-yl)amino)-4-fluoro-2-methylphenol-hydrochloride] (20 μg/mL) was dripped onto the gingiva between the mandibular incisors. Changes in diameter of the selected gingival venule were measured by vital microscopy combined with digital photography at specified times. Immunohistochemical staining was used to localize VEGFR2. For controls, the same protocol was used on animals with normal blood sugar levels and healthy gingiva.

RESULTS

There was a significant difference between the baseline venule diameter of the diabetic and the control groups (47 ± 1 and 28 ± 2 μm, respectively). After 15, 30, and 60 minutes of local application of ZM323881, significant vasoconstriction was observed in the venules of diabetic rats compared with the baseline (81.4% ± 4.6%, 81.8% ± 4.4%, and 80.6% ± 5.1%, respectively). The control group showed no change in the venule diameter. The immunohistochemical analysis showed significantly increased VEGFR2 expression in the mast cells along the venules in the diabetic group, whereas mast cells were rarely found in the control group.

CONCLUSIONS

The findings suggest that VEGF expression is increased in gingiva in experimentally induced diabetes. After VEGFR2 activation, the mast cell-derived vasodilatory and inflammatory mediators may contribute markedly to the concomitant changes in the microcirculation.

Endothelial-mesenchymal transition of brain endothelial cells: possible role during metastatic extravasation

Cancer progression towards metastasis follows a defined sequence of events described as the metastatic cascade. For extravasation and transendothelial migration metastatic cells interact first with endothelial cells. Yet the role of endothelial cells during the process of metastasis formation and extravasation is still unclear, and the interaction between metastatic and endothelial cells during transendothelial migration is poorly understood. Since tumor cells are well known to express TGF-β, and the compact endothelial layer undergoes a series of changes during metastatic extravasation (cell contact disruption, cytoskeletal reorganization, enhanced contractility), we hypothesized that an EndMT may be necessary for metastatic extravasation. We demonstrate that primary cultured rat brain endothelial cells (BEC) undergo EndMT upon TGF-β1 treatment, characterized by the loss of tight and adherens junction proteins, expression of fibronectin, β1-integrin, calponin and α-smooth muscle actin (SMA). B16/F10 cell line conditioned and activated medium (ACM) had similar effects: claudin-5 down-regulation, fibronectin and SMA expression. Inhibition of TGF-β signaling during B16/F10 ACM stimulation using SB-431542 maintained claudin-5 levels and mitigated fibronectin and SMA expression. B16/F10 ACM stimulation of BECs led to phosphorylation of Smad2 and Smad3. SB-431542 prevented SMA up-regulation upon stimulation of BECs with A2058, MCF-7 and MDA-MB231 ACM as well. Moreover, B16/F10 ACM caused a reduction in transendothelial electrical resistance, enhanced the number of melanoma cells adhering to and transmigrating through the endothelial layer, in a TGF-β-dependent manner. These effects were not confined to BECs: HUVECs showed TGF-β-dependent SMA expression when stimulated with breast cancer cell line ACM. Our results indicate that an EndMT may be necessary for metastatic transendothelial migration, and this transition may be one of the potential mechanisms occurring during the complex phenomenon known as metastatic extravasation.

Endothelial-mesenchymal transition of brain endothelial cells: possible role during metastatic extravasation

Cancer progression towards metastasis follows a defined sequence of events described as the metastatic cascade. For extravasation and transendothelial migration metastatic cells interact first with endothelial cells. Yet the role of endothelial cells during the process of metastasis formation and extravasation is still unclear, and the interaction between metastatic and endothelial cells during transendothelial migration is poorly understood. Since tumor cells are well known to express TGF-β, and the compact endothelial layer undergoes a series of changes during metastatic extravasation (cell contact disruption, cytoskeletal reorganization, enhanced contractility), we hypothesized that an EndMT may be necessary for metastatic extravasation. We demonstrate that primary cultured rat brain endothelial cells (BEC) undergo EndMT upon TGF-β1 treatment, characterized by the loss of tight and adherens junction proteins, expression of fibronectin, β1-integrin, calponin and α-smooth muscle actin (SMA). B16/F10 cell line conditioned and activated medium (ACM) had similar effects: claudin-5 down-regulation, fibronectin and SMA expression. Inhibition of TGF-β signaling during B16/F10 ACM stimulation using SB-431542 maintained claudin-5 levels and mitigated fibronectin and SMA expression. B16/F10 ACM stimulation of BECs led to phosphorylation of Smad2 and Smad3. SB-431542 prevented SMA up-regulation upon stimulation of BECs with A2058, MCF-7 and MDA-MB231 ACM as well. Moreover, B16/F10 ACM caused a reduction in transendothelial electrical resistance, enhanced the number of melanoma cells adhering to and transmigrating through the endothelial layer, in a TGF-β-dependent manner. These effects were not confined to BECs: HUVECs showed TGF-β-dependent SMA expression when stimulated with breast cancer cell line ACM. Our results indicate that an EndMT may be necessary for metastatic transendothelial migration, and this transition may be one of the potential mechanisms occurring during the complex phenomenon known as metastatic extravasation.

Rodent models of complement activation-related pseudoallergy: Inducers, symptoms, inhibitors and reaction mechanisms

Complement activation-related pseudoallergy (CARPA) is a hypersensitivity reaction to intravenous administration of nanoparticle-containing medicines (nanomedicines). This review focuses on CARPA in rodent models: rats, mice, guinea pigs and rabbits. Information on all aspects of hypersensitivity reactions caused by known complement activators (zymosan, cobra venom factor) and different nanomedicines (liposomes, other drug carrier nanocarriers) in these species has been compiled and analyzed, trying to highlight the similarities and differences. What is most common in all species’ reactions to i.v. complement activators, liposomes and other nanoparticles is a dose-dependent hemodynamic and cardiopulmonary disturbance manifested in acute, reversible rise or fall of blood pressure and respiratory distress that can lead to shock. Other symptoms include heart rate changes, leukopenia followed by leukocytosis, thrombocytopenia, hemoconcentration due to fluid extravasation (rise of hematocrit) and rise of plasma thromboxane B2. The results of a recent rat study are detailed, which show that rats are 2–3 orders of magnitude less sensitive to liposome-induced CARPA than pigs or hypersensitive humans. It is concluded that CARPA can be studied in rodent models, but they do not necessarily mimic the human reactions in terms of symptom spectrum and sensitivity.

Pulmonary intravascular macrophages: prime suspects as cellular mediators of porcine CARPA

Pigs provide a highly sensitive and quantitative in vivo model for complement (C) activation-related pseudoallergy (CARPA), a hypersensitivity reaction caused by some state-of-art nanomedicines. In an effort to understand the mechanism of the pigs’ unique sensitivity for CARPA, this review focuses on pulmonary intravascular macrophages (PIMs), which are abundantly present in the lung of pigs. These cells represent a macrophage subpopulation whose unique qualities explain the characteristic symptoms of CARPA in this species, most importantly the rapidly (within minutes) developing pulmonary vasoconstriction, leading to elevation of pulmonary arterial pressure. The unique qualities of PIM cells include the following; 1) they are strongly adhered to the capillary walls via desmosome-like intercellular adhesion plaques, which secure stable and lasting direct exposition of the bulk of these cells to the blood stream; 2) their ruffled surface engaged in intense phagocytic activity ensures efficient binding and phagocytosis of nanoparticles; 3) PIM cells express anaphylatoxin receptors, this way C activation can trigger these cells, 4) they also express pattern recognition molecules on their surface, whose engagement with certain coated nanoparticles may also activate these cells or act in synergy with anaphylatoxins and, finally 5) their high metabolic activity and capability for immediate secretion of vasoactive mediators upon stimulation explain the circulatory blockage and other robust physiological effects that their stimulation may cause. These qualities taken together with reports on liposome uptake by PIM cells during CARPA and the possible presence of these cells in human lung suggests that PIM cells may be a potential therapeutic target against CARPA.

Paradoxical rise of hemolytic complement in the blood of mice during zymosan- and liposome-induced CARPA: a pilot study

The complement (C) activating effect of zymosan and liposomal drugs (AmBisome, Caelyx) leads to significant C consumption in rats, dogs, pigs and other species in vivo, as reflected by a fall in hemolytic complement activity (HCA) of their plasma. However, the acute C activating effect of zymosan and liposomal drugs is unclear in the mouse. Therefore, using sheep red blood cells, we assayed the HCA of plasma obtained from apolipoprotein E-deficient (ApoE) as well as from background C57BL/6 (BL6) mice. Intravenous (i.v.) administration of C activators led to a significant rise (up to 40%) in HCA of the plasma. The HCA steadily rose up to 30 min in ApoE mice, while it peaked at 3 min in BL6 mice, returning to baseline thereafter. The elevated HCA after IV injection of C activators is “paradoxical” in mice, since it implies an increase rather than a decrease in C levels in the blood. One possible explanation of the phenomenon is hemoconcentration due to anaphylatoxin-induced capillary leakage, resulting in an apparent rise of HCA. In conclusion, these preliminary observations highlight, for the first time, a species-dependent opposing impact of C activation and the resulting anaphylatoxin actions on hemolytic complement activity.

LPS-induced delayed preconditioning is mediated by Hsp90 and involves the heat shock response in mouse kidney

Introduction

We and others demonstrated previously that preconditioning with endotoxin (LPS) protected from a subsequent lethal LPS challenge or from renal ischemia-reperfusion injury (IRI). LPS is effective in evoking the heat shock response, an ancient and essential cellular defense mechanism, which plays a role in resistance to, and recovery from diseases. Here, by using the pharmacological Hsp90 inhibitor novobiocin (NB), we investigated the role of Hsp90 and the heat shock response in LPS-induced delayed renal preconditioning.

Methods

Male C57BL/6 mice were treated with preconditioning (P: 2 mg/kg, ip.) and subsequent lethal (L: 10 mg/kg, ip.) doses of LPS alone or in combination with NB (100 mg/kg, ip.). Controls received saline (C) or NB.

Results

Preconditioning LPS conferred protection from a subsequent lethal LPS treatment. Importantly, the protective effect of LPS preconditioning was completely abolished by a concomitant treatment with NB. LPS induced a marked heat shock protein increase as demonstrated by Western blots of Hsp70 and Hsp90. NB alone also stimulated Hsp70 and Hsp90 mRNA but not protein expression. However, Hsp70 and Hsp90 protein induction in LPS-treated mice was abolished by a concomitant NB treatment, demonstrating a NB-induced impairment of the heat shock response to LPS preconditioning.

Conclusion

LPS-induced heat shock protein induction and tolerance to a subsequent lethal LPS treatment was prevented by the Hsp90 inhibitor, novobiocin. Our findings demonstrate a critical role of Hsp90 in LPS signaling, and a potential involvement of the heat shock response in LPS-induced preconditioning.

Activation of the miR-17 family and miR-21 during murine kidney ischemia-reperfusion injury

BACKGROUND

Ischemia-reperfusion (I/R) is the main cause of acute kidney injury (AKI) in patients. We investigated renal microRNA (miRNA) expression profiles and the time course of changes in selected miRNA expressions after renal I/R to characterize the miRNA network activated during development and recovery from AKI.

METHODS AND RESULTS

One day after lethal (30 minutes) and sublethal (20 minutes) renal ischemia, AKI was verified by renal histology (tubular necrosis, regeneration), blood urea nitrogen (BUN) level, renal mRNA expression, and plasma concentration of neutrophil gelatinase-associated lipocalin (NGAL) in C57BL/6J mice. On the first day after 30-minute, lethal I/R miR-21, miR-17-5p, and miR-106a were elevated out of the 21 miRNAs successfully profiled on the Luminex multiplex assay. After 20-minute, sublethal I/R, renal miR-17-5p and miR-106a expressions were elevated on the first and second days of reperfusion, while miR-21 expression increased later and lasted longer. Renal miR-17-5p and miR-21 expressions correlated with each other. Renal function returned to normal on the fourth day after sublethal I/R.

CONCLUSIONS

Our results demonstrate that besides miR-21, miR-17-5p, and miR-106a are additionally activated during the maintenance and recovery phases of renal I/R injury. Furthermore, a correlation between renal miR-17-5p and miR-21 expressions warrants further investigation of how they may influence each other and the outcome of renal ischemia-reperfusion injury.

Chlorine dioxide is a size-selective antimicrobial agent

Background / Aims

ClO₂, the so-called “ideal biocide”, could also be applied as an antiseptic if it was understood why the solution killing microbes rapidly does not cause any harm to humans or to animals. Our aim was to find the source of that selectivity by studying its reaction-diffusion mechanism both theoretically and experimentally.

Methods

ClO₂ permeation measurements through protein membranes were performed and the time delay of ClO₂ transport due to reaction and diffusion was determined. To calculate ClO₂ penetration depths and estimate bacterial killing times, approximate solutions of the reaction-diffusion equation were derived. In these calculations evaporation rates of ClO₂ were also measured and taken into account.

Results

The rate law of the reaction-diffusion model predicts that the killing time is proportional to the square of the characteristic size (e.g. diameter) of a body, thus, small ones will be killed extremely fast. For example, the killing time for a bacterium is on the order of milliseconds in a 300 ppm ClO₂ solution. Thus, a few minutes of contact time (limited by the volatility of ClO₂) is quite enough to kill all bacteria, but short enough to keep ClO₂ penetration into the living tissues of a greater organism safely below 0.1 mm, minimizing cytotoxic effects when applying it as an antiseptic. Additional properties of ClO₂, advantageous for an antiseptic, are also discussed. Most importantly, that bacteria are not able to develop resistance against ClO₂ as it reacts with biological thiols which play a vital role in all living organisms.

Conclusion

Selectivity of ClO₂ between humans and bacteria is based not on their different biochemistry, but on their different size. We hope initiating clinical applications of this promising local antiseptic.

[Investigation of the venodilatory effect of vascular endothelial growth factor (VEGF) in rat gingiva]

VEGF induces proliferation of endothelial cells, stimulates angiogenesis, and increases vascular permeability in many organs. Nevertheless, we have only limited information about its role on gingival hemodynamics, especially in venules. Therefor the aim of this study was to assess the acute circulatory effects of VEGF on rat gingival venules by means of the following protocol. Wister rats (n=63) were devided into five study groups after anesthesia; each animal received 10 microl of experimental solution dripped onto the lower interincisal gingiva. The groups included: 1) saline control (after the experiment, gingiva was excised for VEGF receptor 2 [VEGFR2] immunohistochemistry); 2) VEGF (0.1, 1, 10, or 50 microg/ml); 3) VEGF2 receptor antagonist 5-((7-benzyloxyquinazolin-4-yl)amino)-4-fluoro-2-methyl-phenol-hydrochloride (ZM323881; 20 microg/ml); 4) ZM323881 (20 microg/ml) followed by VEGF application (50 microg/ml after 15 minutes); and 5) VEGF (10 microg/ml), these rats were premedicated with nitric oxide (NO) synthase blocker (NG-nitro-L-arginine-methyl-ester [L-NAME]; 1 mg/ml in drinking water) for 1 week before the experiment. Changes in gingival superficial venule diameter were measured by vital microscopy prior to and 1, 5, 15, 30, and 60 minutes after the administration of the experimental solutions. According to our findings, VEGF dose-dependently increased the venular diameter compared to saline. ZM323881 alone did not cause any alteration. Premedication with ZM323881 or L-NAME decreased the dilatory effects of VEGF. Occassionally moderate VEGFR2 immunohistochemical labeling was observed in the wall components of the venules. Concluding our results we can say, that there is no remarkable VEGF production under physiologic circumstances in rat gingiva, but VEGF is able to increase gingival blood flow through the activation of VEGF2 receptors and consequent NO release.

Characterization and role of SCAI during renal fibrosis and epithelial-to-mesenchymal transition

During progressive tubulointerstitial fibrosis, renal tubular epithelial cells transform into α-smooth muscle actin (SMA)-expressing myofibroblasts via epithelial-to-mesenchymal transition (EMT). SMA expression is regulated by transforming growth factor (TGF)-β1 and cell contact disruption, through signaling events targeting the serum response factor-myocardin-related transcription factor (MRTF) complex. MRTFs are important regulators of fibrosis, tumor cell invasion, and metastasis. Consistent with the role of MRTFs in tumor progression, suppressor of cancer cell invasion (SCAI) was recently identified as a negative regulator of MRTF. Herein, we studied the role of SCAI in a fibrotic EMT model established on LLC-PK1 cells. SCAI overexpression prevented SMA promoter activation induced by TGF-β1. When co-expressed, it inhibited the stimulatory effects of MRTF-A, MRTF-B or the constitutive active forms of RhoA, Rac1, or Cdc42 on the SMA promoter. SCAI interfered with TGF-β1-induced SMA, connective tissue growth factor, and calponin protein expression; it rescued TGF-β1-induced E-cadherin down-regulation. IHC studies on human kidneys showed that SCAI expression is reduced during fibrosis. Kidneys of diabetic rats and mice with unilateral ureteral obstruction depicted significant loss of SCAI expression. In parallel with the decrease of SCAI protein expression, diabetic rat and mouse kidneys with unilateral ureteral obstruction showed SMA expression, as evidenced by using Western blot analysis. Finally, TGF-β1 treatment of LLC-PK1 cells attenuated SCAI protein expression. These data suggest that SCAI is a novel transcriptional cofactor that regulates EMT and renal fibrosis.

A porcine model of complement-mediated infusion reactions to drug carrier nanosystems and other medicines

Intravenous administration of low (milligram) doses of nanoparticulate materials in pigs can lead to acute cardiopulmonary, hemodynamic, hematological, biochemical and dermatological changes within minutes, mimicking the human infusion (or anaphylactoid) reactions to many state-of-the-art (nano)medicines and biologicals. Because of the causal role of complement (C) activation, the phenomenon was called C activation-related pseudoallergy (CARPA). This review summarizes the available information on porcine CARPA caused by different liposomes and polymers. It provides methodical details of the model and addresses the quantitation, sensitivity, specificity, reproducibility and variability of symptoms caused by different reactogenic drugs. We describe a unique feature of the model: the rise of tachyphylaxis (self-induced tolerance) as a function of structural properties of reactogenic agents. For drugs that cause tachyphylactic CARPA, such as liposomal doxorubicin (Doxil), the review recapitulates a recently reported method of desensitization, which may prevent this, as well as many similar hypersensitivity reactions. In explaining the underlying mechanism of tachyphylactic CARPA, a new theory on "double hit" is outlined, wherein the pulmonary intravascular macrophages (PIM cells) of pigs give aggravated response to simultaneous stimulation of their anaphylatoxin and other surface receptors (e.g., toll-like, PAMP, DAMP or mannose) that recognize vesicle surface molecular patterns. The porcine CARPA model might provide unique advantages in studying the mechanism of severe hypersensitivity reactions in man to i.v. drugs, as well as in identifying drugs and drug carriers that may cause such reactions.