Involvement of the Bradykinin B1 Receptor in Microglial Activation: In Vitro and In Vivo Studies.

The importance of brain inflammation to Alzheimer's disease (AD) pathogenesis has been accepted of late, with it currently being held that brain inflammation aggravates AD pathology. One important aspect of brain inflammation is the recruitment and activation of microglia, a process termed microgliosis. Kinins and bradykinin (BK), in particular, are major pro-inflammatory mediators in the periphery, although all of the factors comprising the kinin system have also been described in the brain. Moreover, it was shown that the amyloid ß (Aß) peptide (a component of AD plaques) enhances kinin secretion and activates BK receptors that can, in turn, stimulate Aß production. Still, the role of bradykinin in modulating brain inflammation and AD is not completely understood. In this study, we aimed to investigate the roles of the bradykinin B1 receptor (B1R) and bradykinin B2 receptor (B2R) in regulating microglial secretion of pro-inflammatory factors in vitro. Furthermore, the effects of intranasal administration of specific B1R and B2R antagonists on Aß burden and microglial accumulation in the brains of transgenic AD mice were studied. The data obtained show that neither R-715 (a B1R antagonist) nor HOE 140 (a B2R antagonist) altered microglial cell viability. However, R-715, but not HOE 140, markedly increased lipopolysaccharide-induced nitric oxide (NO) and tumor necrosis factor-alpha (TNF-α) release, as well as inducible nitric oxide synthase expression in BV2 microglial cells. Neither antagonist altered NO nor TNF-α production in non-stimulated cells. We also showed that intranasal administration of R-715 but not HOE 140 to 8-week-old 5X familial AD mice enhanced amyloid burden and microglia/macrophage accumulation in the cortex. To conclude, we provide evidence supporting a role of B1R in brain inflammation and in the regulation of amyloid deposition in AD mice, possibly with microglial/macrophage involvement. Further studies are required to test whether modulation of this receptor can serve as a novel therapeutic strategy for AD.

Angiotensin Converting Enzyme Inhibitors Ameliorate Brain Inflammation Associated with Microglial Activation: Possible Implications for Alzheimer's Disease.

Angiotensin converting enzyme (ACE) converts Angiotensin I to a potent vasoconstrictor angiotensin II (ANG II). ACE inhibitors (ACEIs) are widely used for the management of hypertension. All components of the renin-angiotensin system (RAS) have also been identified in the brain. In addition to cytokines, neuromodulators such as ANG II can induce neuroinflammation. Moreover, in Alzheimer's disease (AD) models, where neuroinflammation occurs and is thought to contribute to the propagation of the disease, increased levels of ANG II and ACE have been detected. However, the specific effect of ACEIs on neuroinflammation and AD remains obscure. The present study suggests that captopril and perindopril, centrally active ACEIs, may serve as modulators for microglial activation associated with AD. Our in vitro study investigated the effect of both ACEIs on nitric oxide (NO), tumor necrosis factor- α (TNF-α) release and inducible NO synthase (iNOS) expression in lipopolysaccharide (LPS)-induced BV2 microglia. Exposure of BV2 microglia to ACEIs significantly attenuated the LPS-induced NO and TNF-α release. In vivo, short term intranasal administration of perindopril or captopril to 5 Familial AD (5XFAD) mice significantly reduced amyloid burden and CD11b expression (a microglial marker) or only CD11b expression respectively, in the cortex of 5XFAD. Long-term intranasal administration of captopril to mice reduced amyloid burden with no effect on CD11b expression. We provide evidence that intranasal delivery of ACEI may serve as an efficient alternative for their systemic administration, as it results in the attenuation of microglial accumulation and even the reduction of Amyloid ß (Aß) plaques.

Telmisartan Modulates Glial Activation: In Vitro and In Vivo Studies.

The circulating renin-angiotensin system (RAS), including the biologically active angiotensin II, is a fundamental regulatory mechanism of blood pressure conserved through evolution. Angiotensin II components of the RAS have also been identified in the brain. In addition to pro-inflammatory cytokines, neuromodulators, such as angiotensin II can induce (through angiotensin type 1 receptor (AT1R)) some of the inflammatory actions of brain glial cells and influence brain inflammation. Moreover, in Alzheimer's disease (AD) models, where neuroinflammation occurs, increased levels of cortical AT1Rs have been shown. Still, the precise role of RAS in neuroinflammation is not completely clear. The overall aim of the present study was to elucidate the role of RAS in the modulation of glial functions and AD pathology. To reach this goal, the specific aims of the present study were a. to investigate the long term effect of telmisartan (AT1R blocker) on tumor necrosis factor-α (TNF-α), interleukin 1-ß (IL1-ß) and nitric oxide (NO) release from glial cells. b. to examine the effect of intranasally administered telmisartan on amyloid burden and microglial activation in 5X familial AD (5XFAD) mice. Telmisartan effects in vivo were compared to those of perindopril (angiotensin converting enzyme inhibitor). Long-term-exposure of BV2 microglia to telmisartan significantly decreased lipopolysaccharide (LPS) -induced NO, inducible NO synthase, TNF-α and IL1-ß synthesis. The effect of Telmisartan on NO production in BV2 cells was confirmed also in primary neonatal rat glial cells. Intranasal administration of telmisartan (1 mg/kg/day) for up to two months significantly reduced amyloid burden and CD11b expression (a marker for microglia) both in the cortex and hipoccampus of 5XFAD. Based on the current view of RAS and our data, showing reduced amyloid burden and glial activation in the brains of 5XFAD transgenic mice, one may envision potential intervention with the progression of glial activation and AD by using AT1R blockers.

Differential regulation of astrocyte prostaglandin response by kinins: possible role for mitogen activated protein kinases.

The role of kinins, well known as peripheral inflammatory mediators, in the modulation of brain inflammation is not completely understood. The present data show that bradykinin, a B2 receptor agonist, enhanced both basal and lipopolysaccharide (LPS)-induced cyclooxygenase-2 mRNA and protein levels and prostaglandin E2 synthesis in primary rat astrocytes. By contrast, Lys-des-Arg(9)-bradykinin, which is a bradykinin breakdown product and a selective kinin B1 receptor agonist, attenuated both basal and LPS-induced astrocyte cyclooxygenase-2 mRNA levels and prostaglandin E2 production. Pre-treating the cells with p42/p44 MAPK but not with JNK or p38 inhibitors completely abrogated PGE2 synthesis in cells stimulated with LPS in the presence of bradykinin or bradykinin B1 receptor agonist. Bradykinin, but not the bradykinin B1 receptor agonist, augmented p42/p44 MAPK phosphorylation. The phosphorylation of JNK and p38 was not altered upon exposure to Bradykinin or the bradykinin B1 receptor agonist. These results suggest that the dual delayed effect of kinins on PGE2 synthesis may be due to differential regulation of COX-2 and signaling molecules such as p42/p44 MAPKs. Thus, kinins may exert opposing actions on brain inflammation and neurodegenerative diseases.

A novel red grape cells complex: health effects and bioavailability of natural resveratrol.

In this study, we present a novel product consisted of red grape cells (RGC) grown in culture and evaluated its effect on human LDL oxidation (in vitro) and inflammatory stress (in an in vivo rat model). We analyzed RGC for its polyphenols content and characterized RGC-derived resveratrol (RES) and its properties; and finally, we characterized the pharmacokinetic profile of RGC-RES in human plasma. RGC has demonstrated a strong inhibitory effect on LDL oxidation with IC50 as low as 8.0 µg/ml. RGC significantly reduced rats inflamed paw size induced by carrageenan injection. LC/MS analysis has shown that the main polyphenol in RGC was RES with one hexose moiety. The human pharmacokinetic analysis (clinicaltrials.gov NCT01747252) revealed relatively high bioavailability and two distinctly separated plasma concentration peaks at 1 and 5 h. The present study demonstrates antioxidant and anti-inflammatory traits of RGC that warrants further research in both pre-clinical and clinical settings.

Bradykinin decreases nitric oxide release from microglia via inhibition of cyclic adenosine monophosphate signaling.

Bradykinin (BK) is a major potent inflammatory mediator outside the central nervous system. In Alzheimer's disease, BK release and BK receptor expression in brain tissues are upregulated relatively early during the course of the disease. Hence, BK was believed to promote neuroinflammation. However, BK was recently reported to possess anti-inflammatory and neuroprotective roles. Exposure of BV2 microglial cell line to BK lead to a decrease in NO release from unstimulated cells as well as a dose-dependent attenuation, mediated by both B1 and B2 receptors, in lipopolysaccharide (LPS)-induced NO production. In this study we examined whether cyclic adenosine monophosphate (cAMP) signaling is involved in BK-mediated effect in microglial nitric oxide (NO) production. A protein kinase A (PKA) inhibitor mimicked the effects of BK, while cAMP elevating agents antagonized BK-mediated NO decrease. Moreover, BK inhibited the activation of cAMP responsive element binding protein (CREB). In addition, BK protected microglial cells from death triggered by combinations of LPS and each of the cAMP elevating agents. Finally, the addition of Gαi protein inhibitor abrogated the effects of BK on NO release, and the expression of Gαi protein in the plasma membrane was induced by BK. These results suggest that BK-mediated reduction in microglial NO production depends on coupling to Gi protein and also involves inhibition of cAMP-PKA-CREB signaling.

Controlling bleeding from superficial wounds by the use of topical alpha adrenoreceptor agonists spray. A randomized, masked, controlled study.

In an attempt to determine whether alpha adrenergic agonists sprayed directly over the wound are able to reduce a superficial bleeding, phenylephrine (0.25%), oxymetazoline (0.05 and 0.25%) and saline (0.9%) were tested in a rat model. The study was randomized, controlled and quantitative. A total of four incisions were made in each rat, and each solution was sprayed directly on the incision according to a specific protocol. The bleeding times were measured and summed up. Biases were minimized by the fact that each rat received all four solutions, including the control, in all possible combinations. The mean bleeding time after spraying phenylephrine (0.25%) was significantly shorter than the mean bleeding time after spraying saline (1.90 +/- 0.14 min versus 4.80 +/- 0.43 min, respectively, P < 0.001) and significantly shorter than the mean bleeding time after spraying oxymetazoline (0.05 or 0.25%: 4.46 +/- 0.54 and 5.50 +/- 0.58 min, respectively, P < 0.001). No statistically significant difference was found between the mean bleeding time after spraying oxymetazoline (0.05 or 0.25%) compared with saline. We conclude that sprayed phenylephrine (0.25%) can be used for reducing superficial bleedings. This method is simple, cost-effective, does not cause further trauma to the tissue, and can be used to treat several bleedings simultaneously (especially abrasions and lacerations) with a single application, without the need for direct physical contact with the bleeding sites. The method is apparently safe, but further studies are needed to test the systemic effect of the sprayed solution.

Herpes simplex virus thymidine kinase gene transduction enhances tumor growth rate and cyclooxygenase-2 expression in murine colon cancer cells.

Transduction of tumor cells with herpes simplex virus thymidine kinase (HSV-tk) gene and subsequent treatment with the prodrug ganciclovir (GCV) is the most common system utilized to date for "suicide" gene therapy of cancer. In the current report, we show that HSV-tk gene transduction enhances tumor growth rate of murine colon cancer cells, that are implanted subcutaneously in syngeneic mice, and enhances cyclooxygenase-2 (COX-2) protein expression and prostaglandin E(2) (PGE(2)) release in vitro and in vivo. It is further shown that the observed phenomenon is related to the presence of the HSV-tk sequence insert in the retroviral vector used for HSV-tk gene delivery. Transduction of murine colon cancer cells with control vector, carrying the neomycin-resistance gene alone, failed to increase tumor growth rate and COX-2 protein expression or PGE(2) production. On the contrary, it even decreased tumor growth, COX-2 protein expression and PGE(2.) The growth rate of HSV-tk-transduced murine tumors was significantly reduced by treatment with the selective COX-2 inhibitor nimesulide. Additionally, we demonstrate herein that both enhanced growth rate of HSV-tk-transduced murine tumors and increased levels of PGE(2) in HSV-tk-transduced cells persist upon the development of GCV resistance. Taken together, these results provide a better understanding of the direct effect of HSV-tk gene transduction on tumor cell biology and target tumor development.

Prior statin therapy is associated with a decreased rate of severe sepsis.

BACKGROUND: Statins have anti-inflammatory properties that are independent of their lipid-lowering abilities. We hypothesized that statin therapy before the onset of an acute bacterial infection may have a protective effect against severe sepsis. The aim of this study was to determine whether patients treated with statins develop severe sepsis less frequently. METHODS AND RESULTS: In this prospective observational cohort study, consecutive patients admitted with presumed or documented acute bacterial infection were enrolled. The primary outcomes were the rate of severe sepsis and intensive care unit (ICU) admission. Of the 361 patients enrolled, 82 (22.7%) were treated with statins before their admission. Both groups had a similar severity of illness on admission. Severe sepsis developed in 19% of patients in the no-statin group and in only 2.4% of the statin group (P<0.001). Statin treatment was associated with a relative risk of developing severe sepsis of 0.13 (95% CI, 0.03 to 0.52) and an absolute risk reduction of 16.6%. The overall ICU admission rate was 10.2% (37/361): 12.2% of the no-statin group required ICU admission, whereas in the statin group only 3.7% were admitted to the ICU (P=0.025), reflecting a relative risk of ICU admission of 0.30 (95% CI, 0.1 to 0.95). CONCLUSIONS: Prior therapy with statins may be associated with a reduced rate of severe sepsis and ICU admission. If supported by prospective controlled trials, statins may have a role in the primary prevention of sepsis.

Multiple effects of arginine vasopressin on prostaglandin E2 synthesis in fibroblasts.

Recent evidence supports the viewpoint that vasopressin, a neurohypophyseal peptide, should be also considered as a neuroendocrine modulator of immune and inflammatory responses. In this work we investigated the role of vasopressin in the regulation of prostaglandin E(2) synthesis by human dermal fibroblasts. Recombinant human interleukin-1 beta increased prostaglandin E(2) synthesis in fibroblasts about sixfold. The prostaglandin E(2) response to interleukin-1 beta was attenuated by lower concentrations of vasopressin (10(-10)-10(-9) M). By contrast, higher concentrations (10(-8)-10(-7) M) of vasopressin effected significant enhancement of the interleukin-1 beta-induced prostaglandin E(2) synthesis. In a similar way, vasopressin (10(-8)-10(-7) M), in the absence of interleukin-1, significantly increased prostaglandin E(2) production. An inhibitory effect of lower concentrations of vasopressin was also observed on basal production of prostaglandin E(2). The effects of vasopressin on basal and interleukin-1 beta-induced prostaglandin E(2) synthesis were antagonized by selective vasopressin receptor antagonists. The findings presented here disclose a novel modulatory role of vasopressin on prostaglandin E(2) synthesis in human dermal fibroblasts and suggest a possible role of vasopressin in the regulation of inflammation.

Pharmacokinetic dosing of aminoglycosides: a controlled trial.

PURPOSE: To evaluate whether individualized pharmacokinetic dosing of aminoglycosides can reduce nephrotoxicity and improve the outcome of patients with gram-negative sepsis. METHODS: We conducted a prospective controlled trial at a tertiary care university hospital. Eighty-one patients with suspected or documented gram-negative infections were enrolled. All were treated with either gentamicin or amikacin, according to clinical judgement. Patients were allocated to one of two groups based on the last digit (odd/even) of their identification number. In the study group (pharmacokinetic dosing) of 43 patients, plasma aminoglycoside levels were determined 1 hour after initiation of drug infusion and 8 to 16 hours later to estimate the elimination half-life and volume of distribution, from which the subsequent dosage schedule was calculated. Target peak plasma levels were 20 microg/mL for gentamicin and 60 microg/mL for amikacin. Target trough levels were <1 microg/mL for both drugs. The control group (fixed once-daily dosing) consisted of 38 patients who were prescribed single daily doses of gentamicin or amikacin. The primary endpoints were renal toxicity (> or = 25% increase in serum creatinine level or a serum creatinine level > or = 1.4 mg/dL) and 28-day mortality. RESULTS: The two study groups were similar in age, sex, indications for therapy, Acute Physiology and Chronic Health Evaluation (APACHE) II score, and clinical assessment at baseline. Although the pharmacokinetic group received significantly greater doses of aminoglycosides than did the once-daily group, the incidence of nephrotoxicity was significantly lower in the pharmacokinetic group (5% [2/43] vs. 21% [8/38], P = 0.03). There was no statistically significant difference in 28-day mortality (27% [12/43] vs. 22% [8/38], P = 0.3). CONCLUSION: These results suggest that individualized pharmacokinetic dosing of aminoglycosides reduces the incidence of nephrotoxicity and allows the use of greater doses of aminoglycosides.

Multiple-Dose Studies can be a More Sensitive Assessment for Bioequivalence than Single-Dose Studies : The Case with Omeprazole.

OBJECTIVE: To evaluate the bioequivalence of two enteric-coated formulations of omeprazole, Losec® (reference) and Omepradex® (test). It is hypothesised that formulation differences may be accentuated following multiple-dose administration, and that testing after multiple administration may therefore provide a more sensitive assessment of bioequivalence. STUDY PARTICIPANTS AND DESIGN: The study comprised two parts: an in vitro dissolution test and an in vivo bioavailability study. The latter was a randomised, two-way crossover comparative study after a single dose and after multiple doses in healthy volunteers. Forty subjects were randomly allocated to receive either test or reference product, once daily in the morning, and blood samples were taken on days 1 and 5. Standard pharmacokinetic analyses were performed, and analysis of variance (ANOVA) was used to compare the log-transformed variables in a model including terms for treatment, subject and period. RESULTS: Although both products meet the formal requirements specified by the United States Pharmacopoeia (USP) for enteric-coated articles, the in vitro dissolution experiments revealed widely differing properties for the two tested products. Less than 10% of the drug content was recovered from the Omepradex® formulation following a pre-exposure to pH 3 or 4, compared with over 90% recovered from the Losec® formulation. These findings were in agreement with the results of the in vivo bioavailability study, which showed that the two products differed in both their rate and extent of absorption after a single dose and following multiple doses. The products failed the bioequivalence test for area under the plasma concentration-time curve (AUC) and maximum plasma drug concentration (Cmax) after a single dose [AUC: test/reference ratio 0.85, 90% confidence interval (0.76-0.95); Cmax: test/reference ratio 0.85, 90% confidence interval (0.75-0.95)], and the difference between the formulations was even more pronounced after multiple doses [AUC: test/reference ratio 0.73, 90% confidence interval (0.65-0.83); Cmax: test/reference ratio 0.71, 90% confidence interval (0.63-0.81)]. CONCLUSIONS: These data suggest that bioequivalence studies on enteric-coated proton pump inhibitors should include both single- and multiple-dose elements to be fully decisive. The two omeprazole products failed to show bioequivalence, with the observed differences being even more apparent after multiple doses, as postulated. Based on this study, the two products may not be considered either therapeutically equivalent or interchangeable.