Role of a Pharmacist in Postdischarge Care for Patients With Kidney Disease: A Scoping Review

OBJECTIVE

The objective was to explore and describe the role of pharmacists in providing postdischarge care to patients with kidney disease.

DATA SOURCES

PubMed, Embase (Elsevier), CINAHL (Ebscohost), Web of Science Core Collection, and Scopus were searched on January 30, 2023. Publication date limits were not included. Search terms were identified based on 3 concepts: kidney disease, pharmacy services, and patient discharge. Experimental, quasi-experimental, observational, and qualitative studies, or study protocols, describing the pharmacist's role in providing postdischarge care for patients with kidney disease, excluding kidney transplant recipients, were eligible.

STUDY SELECTION AND DATA EXTRACTION

Six unique interventions were described in 10 studies meeting inclusion criteria.

DATA SYNTHESIS

Four interventions targeted patients with acute kidney injury (AKI) during hospitalization and 2 evaluated patients with pre-existing chronic kidney disease. Pharmacists were a multidisciplinary care team (MDCT) member in 5 interventions and were the sole provider in 1. Roles commonly identified include medication review, medication reconciliation, medication action plan formation, kidney function assessment, drug dose adjustments, and disease education. Some studies showed improvements in diagnostic coding, laboratory monitoring, medication therapy problem (MTP) resolution, and patient education; prevention of hospital readmission was inconsistent. Limitations include lack of standardized reporting of kidney disease, transitions of care processes, and differences in outcomes evaluated.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

This review identifies potential roles of a pharmacist as part of a postdischarge MDCT for patients with varying degrees of kidney disease.

CONCLUSIONS

The pharmacist's role in providing postdischarge care to patients with kidney disease is inconsistent. Multidisciplinary care teams including a pharmacist provided consistent identification and resolution of MTPs, improved patient education, and increased self-awareness of diagnosis.

Examining the Impact of Antimicrobial Fluoroquinolones on Human DNA Topoisomerase IIα and IIβ

Fluoroquinolones are a class of widely prescribed antibiotics with a broad range of activity against Gram-positive, Gram-negative, and some atypical microbes. Unfortunately, these drugs are associated with significant adverse events including neuropathy, tendinopathy, cardiac rhythm abnormalities, and mental health side effects. The mechanism by which fluoroquinolones cause many of these toxicities is unknown. The antibacterial mechanism of action involves disruption of the catalytic mechanism of type-II topoisomerases in bacteria, namely topoisomerase IV and DNA gyrase. Fluoroquinolones inhibit the ability of the enzymes to ligate cleaved DNA and result in single- and double-stranded DNA breaks. Thus, there is an interest in investigating whether human topoisomerase II is involved in mediating the adverse events associated with quinolones. Previous studies demonstrate some response of human topoisomerase IIα and IIβ to high levels of ciprofloxacin. However, it is not clear whether the concentration of ciprofloxacin utilized in those studies corresponds to concentrations that would be routinely achievable in patients. Therefore, this study set out to examine three clinically relevant fluoroquinolones along with two older agents to determine whether these compounds display activity against topoisomerase IIα and IIβ at drug concentrations that more closely approximate typical patient plasma values. On the basis of our evidence, none of the quinolones studied were able to poison DNA cleavage by either human enzyme. Ciprofloxacin, desethylene-ciprofloxacin, and the recently removed from market gemifloxacin were able to inhibit topoisomerase II-mediated DNA relaxation at concentrations of 200-300 μM. On the basis of these data, we propose that human topoisomerase II is not likely to be the main cause of these adverse events and that additional targets need to be identified to clarify the mechanisms underlying quinolone toxicities.

The effect of hydrogen sulfide-releasing naproxen (ATB-346) versus naproxen on formation of stress-induced gastric lesions, the regulation of systemic inflammation, hypoxia and alterations in gastric microcirculation

Clinical use of non-steroidal anti-inflammatory drugs (NSAIDs), such as aspirin or naproxen is limited due to the gastrotoxicity evoked by these compounds. Endogenous hydrogen sulfide (H₂s) and delivered via an H₂s donor have been shown to play important role in the maintenance of gastric mucosal integrity. This study aimed to compare the effects of naproxen and an H₂s-releasing naproxen derivative (ATB-346) on gastric lesion induction by water immersion and restraint stress (WRS), the alterations in gastric blood flow (GBF) and the influence of these drugs on systemic inflammation. Wistar rats were pretreated i.g. with vehicle, naproxen (20 mg/kg) or ATB-346 (equimolar dose) or NaHS (5 mg/kg), the H₂s donor, combined with naproxen and exposed to 3.5 hours of WRS. The gastric lesion number and GBF were assessed by planimetry and laser Doppler flowmetry, respectively. Plasma concentrations of interleukins: IL-1α, IL-1β, IL-2, IL-4, IL-5, IL-6, IL-10, IL-12, interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α) and GM-CSF were determined by Luminex system and gastric mucosal protein expression of cystathionine-γ-lyase (CSE), cystathionine-β-synthase (CBS), 3-mercaptopyruvate sulfurtransferase (3-MST), nuclear factor (erythroid-derived 2)-like 2 (Nrf-2), hypoxia inducible factor-1α (HIF-1α), heme oxygenase-1 (HO-1) and cyclooxygenase (COX-2) were analyzed by Western blot. Pretreatment with naproxen increased the number of WRS stress-induced gastric lesions and significantly decreased GBF as compared with vehicle (p < 0.05). In contrast, pretreatment with ATB-346 or naproxen combined with NaHS significantly reduced WRS-lesions number and elevated GBF as compared with naproxen (p < 0.05). Naproxen significantly increased gastric mucosal protein expression of CSE, Nrf-2 and HIF-1α as compared with vehicle (p < 0.05), but failed to affect CBS, 3-MST and HO-1. ATB-346 significantly increased Nrf-2 and HO-1 protein expression as compared with vehicle (P < 0.05) but did not affect the protein expression of CSE, CBS, 3-MST or HIF-1α. ATB-346 but not naproxen decreased COX-2 protein expression in gastric mucosa compromised by WRS (p < 0.05). Exposure to WRS increased plasma concentration of all investigated cytokines (p < 0.05). ATB-346 but not naproxen decreased plasma content of IL-1α, IL-4, IL-5, IL-6, IL-10, IL-12, TNF-α and IFN-γ in rats exposed to WRS (p < 0.05). We conclude that H₂s through its vasoactive properties attenuates the gastrotoxic effects of naproxen, which increased stress-induced hypoxia in gastric mucosa. In contrast to naproxen, ATB-346 decreased stress-induced systemic inflammation and pro-inflammatory COX-2 expression in the gastric mucosa. The decreased gastrotoxicity of ATB-346 could be due to upregulation of Nrf-2/HO-1 pathway mediated by the release of H₂s.

Modifying the risk of recurrent preterm birth: influence of trimester-specific changes in smoking behaviors

BACKGROUND

Women with at least 1 prior occurrence of premature birth often have demographic and medical risk factors that are not modifiable. However, smoking cessation could be a targeted intervention in which a woman with a history of premature birth may be able to reduce her future risk of recurrence.

OBJECTIVE

This study aims to assess how trimester-specific smoking patterns influence the risk of recurrent premature birth.

STUDY DESIGN

This was a population-based retrospective cohort study of singleton nonanomalous live births in Ohio, 2006-2012 using vital statistics birth records. This analysis was limited to women with at least 1 prior premature birth. Rates of birth <37 weeks were compared among nonsmokers, women who smoked in the 3 months prior to pregnancy and quit in the first vs quit in the second vs quit in the third trimester. Multivariate logistic regression analyses assessed the association between smoking cessation at various time points in pregnancy and recurrent premature birth while adjusting for maternal race, education, Medicaid enrollment, and marital status.

RESULTS

We analyzed the outcomes of 36,432 women with a prior premature birth who subsequently delivered at 20-42 weeks. One third of women with a prior premature birth smoked during pregnancy. Of smokers, 16% quit early in the first trimester, 7% quit in the second, 5% quit in the third trimester, and 72% smoked throughout pregnancy. The rate of recurrent premature birth in nonsmokers was high 28% in this cohort. Smoking in pregnancy with cessation in the first or second trimester was not significantly associated with an increase in recurrent premature birth rates (first trimester, 29% adjusted odds ratio, 0.97 [95% confidence interval, 0.9-1.1], and second trimester, 31% adjusted odds ratio, 1.10 [95% confidence interval, 0.9-1.3], respectively). However, quitting late in pregnancy (third trimester) was associated with a high rate (43%) of delivery <37 weeks, adjusted odds ratio, 1.81 (95% confidence interval, 1.48-2.21). Continued smoking throughout pregnancy was also associated with an increased recurrent premature birth (32%), adjusted odds ratio, 1.14 (95% confidence interval, 1.07-1.22), despite adjustment for concomitant premature birth risk factors.

CONCLUSION

Smoking cessation in pregnancy and its relationship to preterm birth has been studied extensively, and it is widely accepted that smoking in pregnancy increases preterm birth rates. However, this study provides novel information quantifying the risk of recurrent preterm birth and stratifies the increased risk of recurrent preterm birth by trimester-specific smoking behavior. Although women with even 1 prior premature birth are at an inherently high risk of recurrence, women who stopped smoking early in the first 2 trimesters experienced similar preterm birth rates compared with nonsmokers. However, delayed smoking cessation or smoking throughout pregnancy significantly increased recurrent premature birth risk. Smoking cessation is a potential modifiable risk factor for recurrent preterm birth in high-risk pregnancies. This study highlights the importance of early pregnancy smoking cessation in those at especially high risk, women with a prior preterm birth.

[TRENDS IN DEVELOPMENT OF GI-SAFE ANTI-INFLAMMATORY DRUGS]

Despite the introduction of anti-inflammatory drugs that selectively inhibit cyclo-oxygenase-2 (COX-2), and potent inhibitors of gastric acid secretion, the gastrointestinal adverse effects of non-steroidal anti-inflammatory drugs (NSAIDs) remain a significant clinical problem. Combined use of antisecretory drugs and COX-2 inhibitors is helpful to limit the damage in the proximal gastrointestinal tract (stomach and duodenum), but it increases the risk of injury of small intestine and colon. It was proven that proton pump inhibitors and H2 receptor antagonists significantly worsen NSAID-induced small intestinal damage and microbiota balance. Nowadays, there is no proven effective preventative or curative treatment for NSAID-induced enteropathy. The new strategy of gastrointestinal protection is based on the discovery of endogenous cytoprotective molecules such as hydrogen sulfide (H₂S). H2S is a gaseous mediator that produces strong cytoprotective and antioxidant effect on the gastrointestinal tract. The role of H₂S in promoting mucosal integrity, healing of tissue injury and resolution of inflammation has been well documented. In addition, H₂S stimulates productions of other cytoprotective molecules including prostaglandins, carbon monoxide and nitric oxide. Nowadays, the new generation of H₂S-releasing non-steroidal anti-inflammatory drugs is developed and tested in clinical trials. H₂S-NSAIDs possess enhanced anti-inflammatory activity and high gastrointestinal safety.

Monitoring of Urate-Lowering Therapy Among US Veterans Following the 2012 American College of Rheumatology Guidelines for Management of Gout

BACKGROUND

With the prevalence of and hospitalizations for gout increasing, optimizing care for patients with gout is imperative. The 2012 American College of Rheumatology gout guidelines emphasize that timely monitoring is key to achieving serum urate (SUA) goals. Few studies have examined this metric following the 2012 update, and to our knowledge, none have examined a veteran population.

OBJECTIVE

To evaluate adherence to urate-lowering therapy (ULT) monitoring guidelines in a veteran population.

METHODS

This is a single-center, multisite, retrospective chart review of US veterans receiving ULT for gout within the VA (Veterans Affairs) Tennessee Valley Healthcare System from January 1, 2013, to June 30, 2015. The primary end point was percentage of patients with a SUA within 6 months of initial xanthine oxidase inhibitor prescription. Secondary end points included percentage of patients with SUA <6 mg/dL and percentage of patients with uptitration following SUA above goal.

RESULTS

A total of 601 patients met inclusion criteria for the study; after application of exclusion criteria, 505 were analyzed. Of these, 295 patients (58%) did not have a SUA drawn within 6 months, and 162 patients (32%) reached the end of the study period without SUA measured. Of 226 patients with SUA above goal on initial check, 64 (28%) had timely dose adjustment, whereas 143 patients (63%) had no adjustment. A total of 161 patients (32%) had a SUA at goal within the study period.

CONCLUSIONS

Rates of ULT monitoring at a major VA medical center were suboptimal, and improved adherence to guideline recommendations is needed.

Glyprolines exert protective and repair-promoting effects in the rat stomach: potential role of the cytokine GRO/CINC-1

Glyprolines have been reported to exert protective effects in the stomach. In this study, we examined the potential effects of intranasal administration of Pro-Gly-Pro (PGP) and N-acetyl-Pro-Gly-Pro (AcPGP) on experimental gastric ulcer formation and healing. We also studied gastric release of the cytokine GRO/CINC-1, and its potential role in ulcer development and healing. Gastric ulcers were induced in rats by applying acetic acid to the serosa of the stomach. PGP and AcPGP were then administered at a dose of 3.7 μmol/kg once daily on either days 1 - 3 (ulcer formation) or days 4 - 6 (ulcer healing). Measurement of ulcer area and histological examination of gastric tissue were carried out on days 4 and 7 after application of acetic acid. In vitro studies involved addition of the glyprolines to cultured rat gastric epithelial cells with or without lipopolysaccharide. Reverse transcription PCR, real-time PCR and ELISA were used for cytokine analysis. PGP and AcPGP significantly reduced ulcer areas on the 4(th) day and accelerated the healing on the 7(th) day compared with the control. After acetic acid-induced ulceration, the expression of GRO/CINC-1 mRNA in gastric tissue was increased 9-fold versus the sham-operated group. Treatment with PGP or AcPGP both significantly suppressed the expression of GRO/CINC-1 mRNA in gastric tissue. However, the glyprolines did not alter LPS-induced mRNA expression or release of GRO/CINC-1 from cultured rat gastric epithelial cells, even though those cells were harvested from rats subjected to the ulcer-induction procedure. The results of this study show that intranasal administration of PGP and AcPGP significantly increased resistance against acetic acid-induced ulceration and accelerated healing in the rats. These effects may be due, at least in part, to their ability to reduce the acetic acid-induced GRO/CINC-1 expression and production in gastric tissue.

Effect of Body Weight on Dose of Vitamin K Antagonists

OBJECTIVES

Numerous factors are well documented to affect the response to vitamin K antagonists (VKA), including dietary vitamin K, other drugs, age, pharmacogenetics, and disease states. Body weight is perhaps not as well known as a variable affecting VKA dose. Our aim was to review the literature regarding body weight and VKA dose requirements.

METHODS

We reviewed the English-language literature via PubMed and Scopus using the search terms VKA, warfarin, acenocoumarol, phenprocoumon, fluindione, AND body weight.

RESULTS

Among 32 studies conducted since the widespread use of the international normalized ratio, 29 found a correlation with body weight or body surface area and VKA dose requirement. Warfarin was evaluated in 27 studies and acenocoumarol, phenprocoumon, or fluindione were assessed in 5 investigations.

CONCLUSIONS

Because of varying study methodologies, further study is warranted. Based on current evidence, clinicians should include body weight, along with other established variables when dosing VKA. Most important, obese and morbidly obese patients may require a 30% to 50% increase with the initial dosing of VKA.

Effect of diseases on response to vitamin K antagonists

INTRODUCTION

The purpose of this review article is to summarize the literature on diseases that are documented to have an effect on response to warfarin and other VKAs.

METHODS

We searched the English literature from 1946 to September 2015 via PubMed, EMBASE, and Scopus for the effect of diseases on response vitamin K antagonists including warfarin, acenocoumarol, phenprocoumon, and fluindione.

DISCUSSION

Among many factors modifying response to VKAs, several disease states are clinically relevant. Liver disease, hyperthyroidism, and CKD are well documented to increase response to VKAs. Decompensated heart failure, fever, and diarrhea may also elevate response to VKAs, but more study is needed. Hypothyroidism is associated with decreased effect of VKAs, and obese patients will likely require higher initial doses of VKAs.

CONCLUSION

In order to minimize risks with VKAs while ensuring efficacy, clinicians must be aware of the effect of disease states when prescribing these oral anticoagulants.

Incorrect use of peak flow meters: are you observing your patients?

BACKGROUND

Monitoring peak expiratory flow (PEF) values is one option as part of asthma action plans per national guidelines. PEF assessment is also recommended in emergency department and hospitalized patients. Incorrect use of peak flow meters (PFM) has obvious implications for appropriate decisions by patients and clinicians.

METHODS

We searched the English literature via PubMed and SCOPUS using the following search terms: PEF maneuver; incorrect use of PFM. When pertinent articles were found, we assessed publications cited in those papers. All studies related to incorrect use of PFM in patients with asthma were included.

RESULTS

Nine studies have reported errors in performing the PEF maneuver, including three pediatric and six adult studies. Errors were found at most steps of the maneuver, and inability to perform all steps correctly was common in these investigations. Examples of errors included failure to inhale fully or give maximum effort on exhalation, accelerating air with the tongue and buccal musculature, and performing only one attempt versus three. Gender differences in correct use of PFM are suggested by three adult studies. One study described falsifying PEF values by manipulating the PFM indicator, and another investigation assessed the PEF maneuver in two positions in bed versus the correct posture of standing.

CONCLUSION

Many pediatric and adult patients do not use PFM correctly. Clinicians should regularly observe patients use PFM to detect errors and help ensure correct use and accurate PEF measurements.

Peak expiratory flow in bed? A comparison of 3 positions

BACKGROUND

Current guidelines for the correct peak expiratory flow (PEF) maneuver include standing. In the hospital setting, PEF values are often ordered to assess response to asthma therapy for exacerbations. We have observed that the PEF is sometimes performed with the patient in bed.

METHODS

Healthy adults performed the PEF maneuver in random order, standing, lying back at an ~45° angle on pillows, and sitting, slumped forward ~10° with legs extended. PEF was recorded for 3 attempts in each of the 3 positions.

RESULTS

We enrolled 94 subjects (39 male, 55 female, mean age 24 y) in 2011. Mean PEF in the standing position (669 ± 42 L/min) was significantly higher than in the lying back (621 ± 42 L/min) (P < .001) and sitting (615 ± 42 L/min) positions in males (P < .001), and, similarly, in females, standing produced a significantly higher mean PEF (462 ± 42 L/min) than the lying back (422 ± 42 L/min) (P < .001) and sitting (447 ± 42 L/min) positions (P < .05).

CONCLUSIONS

Clinicians should ensure that PEF is obtained with patients out of bed and in the standing position.

Comparing dosing of basal insulin analogues detemir and glargine: is it really unit-per-unit and dose-per-dose?

OBJECTIVE

To review the available evidence regarding dosing conversion between glargine and detemir in an effort to assist clinicians in performing dosing conversion.

DATA SOURCES

A MEDLINE literature search was performed using the search terms glargine and detemir for articles published through August 2013.

STUDY SELECTION AND DATA EXTRACTION

All English-language clinical trials were reviewed for inclusion of dosing and/or pharmacokinetic data.

DATA SYNTHESIS

A total of 7 large (n ≥ 258) randomized controlled trials (RCTs) comparing glargine and detemir in patients with type 1 and 2 diabetes had dosing equivalency data available. In these 7 RCTs, on average, a 38% higher detemir dose was required (range = 8.0%-77.2%) to achieve glucose control comparable to that achieved with glargine. A 24-hour isoglycemic clamp study conducted in 11 patients with type 1 diabetes demonstrated that the duration of action of detemir is dose dependent, with increasing doses of detemir resulting in increased duration of action of detemir. Pharmacokinetic studies conducted in patients with type 2 diabetes are conflicting, although the majority of evidence suggests that glargine provides a longer duration of glycemic control as compared with detemir.

CONCLUSIONS

When performing conversion between glargine and detemir, prescribers should be aware that higher doses of detemir as compared with glargine may be necessary to achieve the same glycemic control. Additionally, twice-daily injections of detemir should be considered in clinical situations in which glucose control appears to decline after 12 hours, especially with doses ≤0.4 units/kg/d in patients with type 1 diabetes.

Representation of three-dimensional objects by the rat perirhinal cortex

The perirhinal cortex (PRC) is known to play an important role in object recognition. Little is known, however, regarding the activity of PRC neurons during the presentation of stimuli that are commonly used for recognition memory tasks in rodents, that is, three-dimensional objects. Rats in the present study were exposed to three-dimensional objects while they traversed a circular track for food reward. Under some behavioral conditions, the track contained novel objects, familiar objects, or no objects. Approximately 38% of PRC neurons demonstrated "object fields" (a selective increase in firing at the location of one or more objects). Although the rats spent more time exploring the objects when they were novel compared to familiar, indicating successful recognition memory, the proportion of object fields and the firing rates of PRC neurons were not affected by the rats' previous experience with the objects. Together, these data indicate that the activity of PRC cells is powerfully affected by the presence of objects while animals navigate through an environment; but under these conditions, the firing patterns are not altered by the relative novelty of objects during successful object recognition.

Pro-resolution, protective and anti-nociceptive effects of a cannabis extract in the rat gastrointestinal tract

Cannabis is widely used for treating a number of gastrointestinal ailments, but its use is associated with several adverse effects, particularly when the route of administration is via smoking. In the present study, we tested the effects (in rats) of a simple extract of medicinal cannabis (called "MFF") for its ability to promote resolution of colitis, to prevent gastric damage induced by naproxen, and to reduce gastric distention-induced visceral pain. Intracolonic, but not oral administration of MFF dose-dependently reduced the severity of hapten-induced colitis, an effect not reduced by pretreatment with antagonists of CB1 or CB2 receptors. Significant improvement of symptoms (diarrhea, weight loss) and healing of ulcerated tissue was evident with MFF treatment at doses that did not produce detectable urinary levels of 9-Δ-tetrahydrocannabinol (THC). MFF increased colonic hydrogen sulfide synthesis in healthy rats, but not in rats with colitis, and had no effect on colonic prostaglandin E2 synthesis. Orally, but not systemically administered MFF dose-dependently reduced the severity of naproxen-induced gastric damage, and a CB1 antagonist reversed this effect. MFF prevented gastric distention-induced visceral pain via a CB2-dependent mechanism. These results demonstrate that a simple extract of medicinal cannabis can significantly enhance resolution of inflammation and injury, as well as prevent injury, in the gastrointestinal tract. Interestingly, different cannabinoid receptors were involved in some of the effects. MFF may serve as the basis for a simple preparation of cannabis that would produce beneficial effects in the GI tract with reduced systemic toxicity.

Inflammatory bowel disorders: current and future drugs that modulate adhesion molecules

Infiltration of leucocytes into the mucosa is a hallmark feature of a number of inflammatory bowel disorders, most notably Crohn's disease and ulcerative colitis. The interactions between circulating leucocytes and the vascular endothelium that permit leucocyte migration to a site of injury or infection are mediated via a variety of adhesion molecules. There is now ample evidence for alterations in adhesion molecule expression and function in inflammatory bowel disorders. This raises the possibility that adhesion molecules could be targets for novel therapies. Indeed, many existing anti-inflammatory drugs are capable of modulating adhesion molecule expression or function. Moreover, intensive research is under way to develop more selective and effective modulators of adhesion molecules, in the hope that they will be useful for treating various inflammatory disorders.

Dextran sulfate sodium induces pan-gastroenteritis in rodents: implications for studies of colitis

Dextran sulfate sodium is widely used to induce colitis in rodents. Though given orally in drinking water, this agent is widely believed to produce injury through direct toxic effects on the epithelium, and it has been assumed to produce damage and inflammation only in the colon. Given the apparent toxic effects of dextran sodium sulfate on epithelial cells, its administration orally, and the anticoagulant properties of this agent, we hypothesized that significant damage and inflammation would be produced in regions of the digestive tract proximal to the colon. Groups of rats or mice received DSS (5%) in the drinking water for up to 7 days. Tissues were harvested at various time-points for blind evaluation of damage, and measurement of several markers of inflammation. In both rats and mice given DSS, significant damage and inflammation was produced in the stomach, small intestine and colon. Significant granulocyte infiltration was apparent in all tissues by day 3 of DSS ingestion. Bleeding was evident throughout the small intestine and colon. These studies clearly demonstrate that DSS, when administered orally in drinking water, produces a pan-gastroenteritis, rather than the damage and inflammation being limited to the colon. The damage and inflammation in the stomach and small intestine could contribute to changes in body weight, stool consistency and bleeding, all of which are commonly used as indices of severity of colitis. Beneficial or detrimental effects of therapeutic interventions could be attributable, at least in part, to modulation of injury and inflammation proximal to the colon.

Cardioselective beta-blocker treatment of hypertension in patients with asthma: when do benefits outweigh risks?

BACKGROUND

Benefits outweigh risks of cardioselective beta-blocker therapy in patients with nonsevere asthma and a history of heart failure or myocardial infarction (MI). This review summarizes the risks versus benefits of using cardioselective beta-blockers in the treatment of hypertension in patients with asthma.

METHODS

We searched the English literature from 1976 to 2011 via PubMed, EMBASE, and SCOPUS using the following search terms: "beta-blocker treatment of hypertension" AND "asthma"; "cardioselective beta-blockers" AND "asthma." When pertinent articles were found, we assessed relevant articles cited in those papers. All studies related to cardioselective beta-blocker use in patients with asthma and hypertension were included.

RESULTS

Seven studies with patient populations ranging from 10 to 17 patients evaluated cardioselective beta-blockers in patients with asthma and hypertension. Atenolol and/or immediate-release metoprolol were evaluated in these studies. The duration of beta-blocker therapy in four studies was 1-8 weeks; two studies were single dose and one investigation lasted 8 months. Metoprolol and atenolol were generally well tolerated except at higher doses such as metoprolol >100 mg daily.

CONCLUSION

In the absence of concomitant cardiovascular disease, routine use of beta-blockers for the treatment of hypertension in patients with asthma should be avoided.

Cytokines in inflammatory bowel disease

Over the past decade, much has been learned regarding the role of various cytokines in the pathogenesis of inflammatory bowel disease. Several cytokine ‘knockout’ models in mice have been shown to develop colitis, while alterations in the production of various cytokines has been documented in human Crohn's disease and ulcerative colitis. In recent years, attempts have been made to treat these diseases through modulation of cytokine production or action. This review focuses on the cytokines that have been implicated in the pathogenesis of inflammatory bowel disease. The evidence for and against a role for particular cytokines in intestinal inflammation is reviewed, as is the experimental and clinical data suggesting that cytokines are rational targets for the development of new therapies.

Are we failing to document adequate smoking histories? A brief review 1999-2009

BACKGROUND

Documenting a detailed smoking history is of obvious importance. Failure to adequately document the smoking history may result in the misdiagnosis and management of asthma, and may be associated with a deficiency of care in patients with cardiovascular disease and several other common diseases.

SCOPE

The purpose of this article is to review the evidence over the past decade that demonstrates inadequate documentation of smoking history. A literature search of English language journals from 1999 to 2009 was completed using several databases, including PubMed, MEDLINE, EMBASE, and SCOPUS.

FINDINGS

Fourteen studies demonstrated inadequate documentation of smoking histories by primary care clinicians, specialists, residents, and medical students. Failure to document smoking histories was observed in patients with conditions such as heart failure, coronary artery disease, and asthma. Electronic decision support systems and simple medical record reminders were effective in improving the documentation of smoking histories.

CONCLUSIONS

Failure to adequately document the smoking history appears to be common. Strategies such as electronic decision support systems are needed to correct this problem in order for patients to receive optimal therapy for their appropriate diagnoses.

Lack of effects of acemetacin on signalling pathways for leukocyte adherence may explain its gastrointestinal safety

BACKGROUND AND PURPOSE

Acemetacin is a non-steroidal anti-inflammatory drug which is rapidly bioconverted to indomethacin, but produces significantly less gastric damage than indomethacin. This study was performed to investigate several possible mechanisms that could account for the gastrointestinal tolerability of acemetacin.

EXPERIMENTAL APPROACH

The gastric and intestinal damaging effects of acemetacin and indomethacin were examined in the rat. Effects of the drugs on blood levels of leukotriene B(4) and thromboxane B(2), on leukocyte-endothelial adherence in post-capillary mesenteric venules, and on gastric expression of tumour necrosis factor-alpha (TNF-alpha) were determined. The two drugs were also compared for gastric toxicity in rats pretreated with inhibitors of COX-2 and NOS.

KEY RESULTS

Acemetacin induced significantly less gastric and intestinal damage than indomethacin, despite markedly suppressing COX activity. Indomethacin, but not acemetacin, significantly increased leukocyte adherence within mesenteric venules, and gastric expression of TNF-alpha. Pretreatment with L-nitro-arginine methyl ester or lumiracoxib increased the severity of indomethacin-induced gastric damage, but this was not the case with acemetacin.

CONCLUSIONS AND IMPLICATIONS

The increased gastric and intestinal tolerability of acemetacin may be related to the lack of induction of leukocyte-endothelial adherence. This may be attributable to the reduced ability of acemetacin to elevate leukotriene-B(4) synthesis and TNF-alpha expression, compared to indomethacin, despite the fact that acemetacin is rapidly bioconverted to indomethacin after its absorption.

Suppressive effects of nitric oxide-releasing prednisolone NCX-1015 on the allergic pleural eosinophil recruitment in rats

BACKGROUND

The addition of a nitric oxide (NO)-releasing moiety to prednisolone was shown to enhance the anti-inflammatory activity of this glucocorticoid in some experimental conditions, but its effectiveness in the context of eosinophilic inflammation remains to be elucidated.

OBJECTIVE

This study compared the anti-inflammatory effect of prednisolone to a NO-releasing derivative of prednisolone, NCX-1015, using a model of allergen-evoked eosinophil recruitment in rats. The efficacy of a NO-donor compound, DETA-NONOate, was also assessed for comparison.

METHODS

Wistar rats were actively sensitized with Al(OH)(3) plus ovalbumin and 14 days later challenged with antigen intrapleurally. Treatments were performed locally 1 h before challenge. Cysteinyl-leucotrienes (Cys-LT) and eotaxin were measured by ELISA.

RESULTS

Antigen challenge induced an eosinophil infiltration at 12 h, maximal at 24 h. It also caused an increase in the levels of Cys-LTs in the pleural exudate and in the expression of 5-lipoxygenase (5-LO) in infiltrated leucocytes at 6 h, peaking at 12 h and persisting for at least 24 h. Treatment with equimolar doses of prednisolone and NCX-1015 inhibited the late eosinophil infiltration, although the dose required to produce maximal inhibition was about one-tenth that of prednisolone. Cys-LT generation and 5-LO expression were inhibited by NCX-1015 but not by prednisolone. Treatment with prednisolone combined with the NO-donor DETA-NONOate led to a greater inhibition of the eosinophilia and Cys-LT generation as compared with either drug alone. Administration of the steroid receptor antagonist RU 486, 1 h before prednisolone and NCX-1015, abolished the inhibitory effect of the former, under conditions where it only partially affected the latter.

CONCLUSIONS

Our findings indicate that NCX-1015 provided a greater anti-inflammatory effect than prednisolone on the allergic eosinophil recruitment in rats, suggesting that NO-releasing steroids can be considered as a promising therapeutic approach to allergic diseases.

Mechanisms underlying the anti-inflammatory activity and gastric safety of acemetacin

BACKGROUND AND PURPOSE

Acemetacin is regarded as a pro-drug of indomethacin and induces significantly less gastric damage but the reasons for this greater gastric safety of acemetacin are unclear. The anti-inflammatory effects of acemetacin have been attributed, at least in part, to its hepatic biotransformation to indomethacin. The aim of this study was to determine the effects of acemetacin and indomethacin in an in vivo model of acute inflammation and to examine the importance of biotransformation of acemetacin (to indomethacin) to its anti-inflammatory actions.

EXPERIMENTAL APPROACH

The zymosan airpouch model was used in rats. Indomethacin or acemetacin (2.7-83.8 micromol kg(-1)) were administered orally or directly into the pouch. Leukocyte infiltration, prostaglandin (PG) E(2) and leukotriene (LT) B(4) levels in exudates, and whole blood thromboxane (TX) B(2) synthesis were measured.

KEY RESULTS

Acemetacin was rapidly converted to indomethacin after its administration. Both acemetacin and indomethacin elicited comparable, dose-dependent reductions of leukocyte infiltration and of PGE(2) and TXB(2) synthesis. However, indomethacin induced more gastric damage than acemetacin and elevated LTB(4) production in the airpouch.

CONCLUSIONS AND IMPLICATIONS

The similar effects of acemetacin and indomethacin on leukocyte infiltration and PG synthesis are consistent with rapid biotransformation of acemetacin to indomethacin. Some of this biotransformation may occur extra-hepatically, for instance in inflammatory exudates. Acemetacin probably exerts actions independent of conversion to indomethacin, given the different effects of these two drugs on LTB(4) production. Such differences may contribute to the relative gastric safety of acemetacin compared to indomethacin.

Building a better aspirin: gaseous solutions to a century-old problem

The gastrointestinal adverse effects of nonsteroidal anti-inflammatory drugs (NSAIDs) have been recognized since shortly after the introduction of aspirin to the marketplace over a century ago. However, the underlying pathogenesis of NSAID-induced gastropathy remains incompletely understood. Advances in understanding some of the factors that contribute to the mucosal injury have provided clues for the development of safer NSAIDs. The inhibitory effects of nitric oxide (NO) on NSAID-induced leukocyte adherence were exploited in the development of NO-releasing NSAIDs. As well as eliciting less gastrointestinal damage than conventional NSAIDs, these drugs do not elevate blood pressure and show anti-inflammatory effects, additional to those of the parent drugs. Modification of other drugs in a similar manner (i.e., NO-releasing derivatives) has similarly resulted in more effective drugs. More recently, hydrogen sulphide-releasing derivatives of NSAIDs and of other drugs, have been developed, based on the observed ability of H(2)S to reduce inflammation and pain in experimental models. H(2)S-releasing NSAIDs produce negligible gastric damage and exhibit enhanced anti-inflammatory potency as compared to the parent drugs. The NO-NSAIDs and H(2)S-releasing NSAIDs represent examples of new anti-inflammatory drugs with greatly reduced toxicity and improved therapeutic activity, both created through the concept of exploiting the beneficial effects of endogenous gaseous mediators.

Enhanced activity of a hydrogen sulphide-releasing derivative of mesalamine (ATB-429) in a mouse model of colitis

BACKGROUND AND PURPOSE

Mesalamine is the first-line therapy for colitis, but it lacks potency and is only effective for mild-to-moderate forms of this disease. Hydrogen sulphide has been shown to be a potent, endogenous anti-inflammatory substance, modulating leukocyte-endothelial adhesion and leukocyte migration. The purpose of this study was to determine if an H(2)S-releasing derivative of mesalamine (ATB-429) would exhibit increased potency and effectiveness in a mouse model of colitis.

EXPERIMENTAL APPROACH

Colitis was induced in mice with trinitrobenzene sulphonic acid and the effects of ATB-429 and mesalamine were compared in several treatment regimens. The severity of colitis was determined using several indices, including a disease activity score (comprised of scores for diarrhea, weight loss and fecal blood), colonic myeloperoxidase activity and macroscopic/microscopic scoring of tissue injury.

KEY RESULTS

Irrespective of the treatment regiment, ATB-429 was more effective than mesalamine in reducing the severity of colitis. ATB-429 was particularly effective in reducing granulocyte infiltration into the colonic tissue (by approximately 70%), as well as reducing the expression of mRNA for several key proinflammatory cytokines/chemokines (e.g., TNFalpha, IFNgamma). Treatment with ADT-OH, the H(2)S-releasing moiety of ATB-429, did not affect severity of colitis.

CONCLUSIONS AND IMPLICATIONS

ATB-429 exhibits a marked increase in anti-inflammatory activity and potency in a murine model of colitis, as compared to mesalamine. These results are consistent with recently described anti-inflammatory effects of H(2)S. ATB-429 may represent an attractive alternative to mesalamine for the treatment of inflammatory bowel disease.

Nitric oxide-releasing non-steroidal anti-inflammatory drugs: a new generation of antithrombotics?

Long-term use of aspirin as an antithrombotic agent is limited by its toxicity in the gastrointestinal tract. Even very low doses of aspirin can markedly increase the risk of gastrointestinal bleeding and ulceration. Addition of a nitric oxide (NO)-releasing moiety to non-steroidal anti-inflammatory drugs (NSAIDs) has been shown to greatly reduce their ulcerogenic properties as well as their renal toxicity. We proposed that similar derivatisation of aspirin may yield a potent, gastrointestinal-sparing antithrombotic drug. Two prototype compounds (NCX-4215 and NCX-4016; Nicox SA) have been evaluated thus far. Each shows comparable or better anti-aggregatory activity to aspirin while not inducing detectable gastric damage. Current studies are aimed at determining what the optimal balance is between nitric oxide release and inhibition of thromboxane synthesis to achieve good antithrombotic activity with low toxicity. NO-aspirin derivatives appear to offer great potential as gastrointestinal-sparing antithrombotic drugs.

Evidence that protease activated receptor 2 expression is enhanced in human coronary atherosclerotic lesions

AIM

To investigate protease activated receptor 2 (PAR-2) expression in human coronary atherosclerotic lesions because PAR-2 is involved in the modulation of inflammatory events and vascular function.

METHODS

An immunohistochemical analysis was performed on serial arterial sections, using the following antibodies: MDA2, a murine monoclonal antibody against malondialdehyde lysine epitopes of oxidised low density lipoprotein (oxLDL); HAM-56, a monoclonal antibody against human macrophages/foam cells; B5, a rabbit polyclonal antibody against PAR-2; and SAM11, a mouse monoclonal antibody against human PAR-2. Sections containing at least one lesion showing substantial immunostaining were counted as positive, and results were expressed as per cent of all sections of the same artery.

RESULTS

PAR-2 expression was enhanced in human coronary atherosclerotic lesions. This phenomenon correlated with an increase in oxLDL epitopes in the coronary artery.

CONCLUSION

This study shows for the first time that PAR-2 expression is enhanced in human coronary atherosclerotic lesions, and suggests that PAR-2 dependent cellular trafficking may be one of the regulatory signalling responses to vascular injury. Further pharmacological studies will establish whether modulation (and in which direction) of PAR-2 represents a possible therapeutic target for controlling the vascular response to injury.

Cyclooxygenase 2 mediates post-inflammatory colonic secretory and barrier dysfunction

BACKGROUND AND AIMS

The colonic epithelium plays a key role in host defence. During colitis, epithelial function is impaired, leading to elevated bacterial translocation and exacerbation of inflammation. We previously documented perturbation of epithelial function, in terms of secretion and as a barrier to bacterial translocation, that persisted long after resolution of a bout of colitis in the rat. The mechanisms underlying the epithelial dysfunction are not completely understood.

METHODS

Given the ability of prostaglandin (PG) D2 to suppress colonic epithelial secretion, we investigated the potential roles of this eicosanoid and of cyclooxygenase 2 (COX-2) in mediating post-colitis epithelial secretory and barrier dysfunction.

RESULTS

Six weeks after induction of colitis with trinitrobenzene sulphonic acid, there was marked elevated synthesis of PGD2 and elevated COX-2 expression. Selective COX-2 inhibition abolished the increase in PGD2 synthesis. Colonic chloride secretory responses (in vitro) were significantly diminished relative to those in controls, a defect that was reversed by pre-exposure to a selective COX-2 inhibitor (celecoxib) but not to a selective COX-1 inhibitor (SC-560). The hyporesponsiveness was mimicked by pre-exposure of normal colonic tissue to PGD2, but not to its metabolite, 15-deoxy-Delta(12-14)PGJ2. The post-colitis rats exhibited a 10-fold increase in bacterial colonisation of the colon, and >3-fold increase in bacterial translocation. Twice daily treatment for one week with a selective COX-2 inhibitor (rofecoxib) did not affect bacterial colonisation but abolished the increase in bacterial translocation.

CONCLUSIONS

These studies demonstrate an important role for COX-2, possibly via generation of PGD2, in mediating the prolonged epithelial secretory and barrier dysfunction after a bout of colitis in the rat.

Nitric oxide-releasing mesalamine: potential utility for treatment of inflammatory bowel disease

Nitric oxide can accelerate ulcer healing and exert anti-inflammatory effects. Addition of a nitric oxide-releasing moiety to mesalamine significantly boosts its anti-inflammatory activity. NO-releasing mesalamine suppresses inflammatory cytokine production and reduces leukocyte infiltration.

Role of gastric mucosal and gastric juice cytokine concentrations in development of bisphosphonate damage to gastric mucosa

Previous studies have shown that the bisphosphonates (BP) vary in their damaging effect on the gastric mucosa, and endoscopy scores (erosions or erosions plus ulcers) after 1 and 2 weeks use of BP were significantly lower in H. pylori-positive versus -negative subjects. The mechanism of this damaging effect of BP and the interaction with H. pylori is unknown. As part of a separately reported study of the incidence of gastric damage after 2 weeks of treatment of healthy female postmenopausal volunteers with risedronate (5 mg/day) or alendronate (10 mg/day), gastric aspirates were taken at the time of the baseline esophagogastroduodenoscopy (EGD), and again at 1 and 2 weeks after daily intake of a BP At the time of the third EGD, when the volunteers had been on risedronate or alendronate for 2 weeks, antral biopsies were taken from normal-appearing mucosa. Gastric juice and antral biopsies were assessed for their concentration of the cytokines interleukin-la (IL-1alpha), IL-8, IL-13, and epidermal growth factor (EGF). H. pylori, the use of BP, and development of gastric mucosal lesions had no effect on gastric mucosal concentrations of IL-1alpha, IL-13, or EGF. In contrast, the concentration of IL-8 in antral mucosal biopsies of volunteers given BP for 2 weeks was higher in the presence than in the absence of an H. pylori infection and was increased further in those who develop lesions associated with the use of BP. There was no correlation between gastric mucosal and gastric juice concentrations of IL-8. Gastric juice concentrations of IL-8 and EGF were not affected by H. pylori status, the use of BP, or the development of lesions. However, gastric juice concentrations of IL-1alpha were numerically lower in those who were negative for H. pylori with no mucosal lesions (Hp-L-), intermediate in those who were H. pylori-negative with lesions (Hp-L+), and highest in those who were positive for H. pylori and had lesions (Hp+L+). The gastric juice concentration of IL-13 was threefold higher in the absence than in the presence of H. pylori, and the relative abundance of IL-13 was: Hp-L- >Hp-L+ >Hp+L(-1) >Hp+L+. The prostaglandin E2 concentration in gastric antral biopsies was similar in the four groups and was unchanged with the in vitro biopsy incubation with celecoxib. We speculate that the higher gastric endoscopy scores observed with the use of BP in H. pylori negative as compared with H. pylori positive individuals is due to their lower mucosal concentration of IL-8 as well as the lower gastric juice concentration of IL-1alpha and higher concentration of IL-13.

Suppression of fever at near term is associated with reduced COX-2 protein expression in rat hypothalamus

The fever response is blunted at near term. As the enzyme cyclooxygenase-2 (COX-2) plays a critical role in fever development, we measured its expression in rat hypothalamus during pregnancy and lactation. Western blot analysis revealed a 72-kDa COX-2-immunoreactive band in non-immune-challenged, pregnant rats at day 15 of pregnancy. In contrast, it was almost undetectable at near term and at lactation day 5. COX-2 was significantly induced at the 15th day of pregnancy and at the 5th lactating day after intraperitoneal lipopolysaccharide (50 microg/kg). However, this COX-2 induction was significantly reduced at near term compared with values before and after term. The protein levels of the EP3 receptor in the hypothalamus, one of the prostaglandin E(2) (PGE(2)) receptors suggested to be a key receptor for fever induction, were unaffected throughout the pregnancy and lactation in both non-immune-challenged and lipopolysaccharide-treated rats. These data suggest that suppression of fever at near term is associated with a significantly reduced induction of COX-2 by lipopolysaccharide, resulting in a reduced production of PGE(2). Altered expression of the EP3 receptor does not seem to be involved in this fever refractoriness at near term.

Selective cyclooxygenase-2 inhibitors: after the smoke has cleared

An enormous amount of fanfare and marketing preceded the introduction of selective inhibitors of cyclooxygenase-2 to the marketplace. These drugs were purported to offer equivalent anti-inflammatory and analgesic effects to conventional non-steroidal anti-inflammatory drugs without causing gastrointestinal injury. Now that there is considerable clinical experience with four drugs of this class having been available for at least two years, it is worthwhile re-visiting some of the original claims to determine whether selective cyclooxygenase-2 inhibitors have thus far lived up to their promise. In short, selective cyclooxygenase-2 inhibitors have proven to be somewhat safer in terms of gastrointestinal toxicity, than some (but not all) conventional non-steroidal antiinflammatory drugs. However their efficacy of the selective cyclooxygenase inhibitors has not always matched that of the conventional nonsteroidal anti-inflammatory drugs and there are significant safety concerns with some of the new drugs that deserve very careful consideration.

Selective cyclo-oxygenase-2 inhibitors: cardiovascular and gastrointestinal toxicity

The introduction of selective inhibitors of cyclo-oxygenase-2 to the marketplace has been much anticipated for several years. It would appear that these compounds have lived up to the expectations of having reduced gastrointestinal toxicity and, at least for some indications, of efficacy similar to that of conventional non-steroidal anti-inflammatory drugs. However, there is a growing body of evidence suggesting that cyclo-oxygenase-2 plays a very important role in gastrointestinal mucosal defence, particularly in situations in which the mucosa is damaged or inflamed. Moreover, physiological roles for cyclo-oxygenase-2 both in the renal and cardiovascular systems are becoming better recognized. Inhibition of cyclo-oxygenase-2 can lead to peripheral oedema and hypertension, and may promote thrombosis. Indeed, there is recent evidence of increased rates of myocardial infarction in arthritis patients taking a selective cyclo-oxygenase-2 inhibitor. Use of low-dose aspirin concurrently with use of a selective cyclo-oxygenase-2 inhibitor may provide some degree of protection against the potential cardiovascular toxicity of the latter but both laboratory and clinical studies suggest that the concomitant use of these two types of drugs results in gastrointestinal ulceration comparable to what is seen with conventional non-steroidal anti-inflammatory drugs. These recent results suggest that care must be exercised in the use of selective cyclo-oxygenase-2 inhibitors by individuals who are at increased risk of myocardial infarction and stroke, and the use of low-dose aspirin by these patients may place them at increased risk of gastrointestinal complications.

Prostaglandin biology in inflammatory bowel disease

Similar to in the upper gastrointestinal tract, prostaglandins represent one of the most important components of mucosal defense in the small intestine and colon. The effects of prostaglandins in this context are widespread, ranging from maintenance of blood flow to stimulation of mucus secretion to modulation of the mucosal immune system. There is little doubt that the ability of NSAIDs to cause injury throughout the gastrointestinal tract and to exacerbate IBD is due in large part to the ability of these agents to suppress prostaglandin synthesis. With the advent of selective COX-2 inhibitors, it has become possible to dissect further the roles of prostaglandins in mucosal defense. The weight of evidence collected so far suggests that prostaglandins derived from COX-2 are important in promoting the healing of mucosal injury, in protecting against bacterial invasion, and in down-regulating the mucosal immune system. Suppression of COX-2 in a setting of gastrointestinal inflammation and ulceration has been shown in experimental models to result in impairment of healing and exacerbation of inflammation-mediated injury. In the near future, pharmacologic probes will be available that will permit clinicians to identify better the specific prostaglandin receptors that mediate the effects of this group of mediators on the various aspects of mucosal defense. This identification should permit the development of therapeutic agents that specifically can modulate some aspects of mucosal defense without having undesired effects on other aspects of mucosal function. Such agents may permit clinicians to enhance mucosal repair selectively and to block selectively any contribution of prostaglandins to the pain associated with IBD.

Inflammatory mediators in gastrointestinal defense and injury

Inflammation of the mucosal layer of the gastrointestinal (GI) tract is not only a feature almost always associated with ulceration of those tissues, but it also plays an important role in both the production and healing of the lesions. The mediators that coordinate inflammatory responses also have the capability to alter the resistance of the mucosa to injury induced by noxious substances, while others render the mucosa more susceptible to injury. In this article, we provide a review of the inflammatory mediators that modulate GI mucosal defense. Among the mediators discussed are nitric oxide, the eicosanoids (prostaglandins, leukotrienes, and thromboxanes), neuropeptides, cytokines, and proteinases. Many of these mediators are considered potential therapeutic targets for the treatment of ulcerative diseases of the digestive tract.

Proteinase-activated receptor 2 is an anti-inflammatory signal for colonic lamina propria lymphocytes in a mouse model of colitis

The proteinase-activated receptor 2 (PAR-2) is a member of a family of G protein-coupled receptors for proteases. Proteases cleave PARs within the extracellular N-terminal domains to expose tethered ligands that bind to and activate the cleaved receptors. PAR-2 is highly expressed in colon in epithelial and neuronal elements. In this study we show that PAR-2 activation prevents the development and induces healing of T helper cell type 1-mediated experimental colitis induced by intrarectal administration of 2,4,6-trinitrobenzene sulfonic acid (TNBS) in mice. A role for PAR-2 in the protection against colon inflammation was explored by the use of SLIGRL-NH(2), a synthetic peptide that corresponds to the mouse tethered ligand exposed after PAR-2 cleavage. TNBS-induced colitis was dose-dependently reduced by the administration of SLIGRL-NH(2), whereas the scramble control peptide, LSIGRL-NH(2), was uneffective. This beneficial effect was reflected by increased survival rates, improvement of macroscopic and histologic scores, decrease in mucosal content of T helper cell type 1 cytokines, protein, and mRNA, and a diminished myeloperoxidase activity. SLIGRL-NH(2), but not the scramble peptide, directly inhibited IFN-gamma secretion and CD44 expression on lamina propria T lymphocytes. Protection exerted by PAR-2 in TNBS-treated mice was reverted by injecting mice with a truncated form of calcitonin gene-related peptide and by sensory neurons ablation with the neurotoxin capsaicin. Collectively, these studies show that PAR-2 is an anti-inflammatory receptor in the colon and suggest that PAR-2 ligands might be effective in the treatment of inflammatory bowel diseases.

Inhibition of attaching and effacing lesion formation following enteropathogenic Escherichia coli and Shiga toxin-producing E. coli infection

Enteropathogenic Escherichia coli (EPEC) and Shiga toxin-producing E. coli (STEC) induce cytoskeletal changes in infected epithelial cells. To further characterize host cytosolic responses to infection, a series of specific cell-signaling inhibitors were employed. Initial bacterial adhesion to HEp-2 epithelial cells was not reduced, whereas alpha-actinin accumulation in infected cells was blocked by a phosphoinositide-specific phospholipase C inhibitor (ET-18-OCH3), phosphoinositide 3-kinase inhibitors (wortmannin and LY294002), and a 5-lipoxygenase inhibitor, nordihydroguaretic acid. A cyclooxygenase-2 inhibitor (NS-398), however, did not block alpha-actinin reorganization in response to EPEC and STEC infections. Understanding signal transduction responses to enteric pathogens could provide the basis for the development of novel therapeutic strategies.

Pathogenesis of NSAID-induced gastroduodenal mucosal injury

The use of non-steroidal anti-inflammatory drugs (NSAIDs), even in the era of selective COX-2 inhibitors, remains limited by the ability of these agents to cause gastroduodenal ulceration and bleeding. This damage is caused mainly through the ability of these agents to inhibit prostaglandin synthesis, which has a negative impact on several components of mucosal defence. Many NSAIDs also have topical irritant effects on the epithelium which may be particularly important in the production of small intestinal injury. While the presence of acid in the lumen of the stomach may not be a primary factor in the pathogenesis of NSAID-induced gastroenteropathy it can make an important contribution to the chronicity of these lesions and to bleeding by impairing the restitution process, interfering with haemostasis and inactivating several growth factors that are important in mucosal defence and repair. Through better understanding of the pathogenesis of ulcers induced by NSAIDs, some new approaches to the development of more effective and safer anti-inflammatory drugs have been taken in recent years.

Thrombin-induced platelet endostatin release is blocked by a proteinase activated receptor-4 (PAR4) antagonist

Endostatin is a potent endogenous inhibitor of angiogenesis that was recently shown to be stored in platelets and released in response to thrombin, but not ADP. In the present study, we have tested the hypothesis that thrombin-induced endostatin release from rat platelets is mediated via proteinase-activated receptor-4 (PAR4). Immunoprecipitation and Western blotting confirmed that endostatin is contained within rat platelets. Aggregation and release of endostatin could be elicited by thrombin (0.5 - 1.0 U ml(-1)) or by specific PAR4 agonist (AYPGKF-NH(2); AY-NH(2); 15 - 50 microM). Significant release of endostatin could be induced by a dose of thrombin below that necessary for induction of aggregation. An adenosine diphosphate (ADP) scavenger, apyrase, inhibited the platelet aggregation induced by thrombin, but not the release of endostatin. In contrast, a selective PAR4 antagonist (trans-cinnamoyl-YPGKF-NH(2); tcY-NH(2)) prevented endostatin release and aggregation induced by thrombin or by AY-NH(2). We conclude that thrombin-induced endostatin release from rat platelets is PAR4-mediated via an ADP-independent mechanism that can occur independently of platelet aggregation.

Persistent epithelial dysfunction and bacterial translocation after resolution of intestinal inflammation

Epithelial secretion may play an important role in reducing bacterial colonization and translocation in intestine. If so, secretory dysfunction could result in increased susceptibility to infection and inflammation. We investigated whether long-term colonic secretory dysfunction occurs after a bout of colitis and if this is accompanied by an increase in bacterial colonization and translocation. Rats were studied 6 wk after induction of colitis with trinitrobenzene sulfonic acid when inflammation had completely resolved, and epithelial permeability was normal. Intestinal loops were stimulated with either Clostridium difficile toxin A or a phosphodiesterase inhibitor. In vitro, colonic tissue from previously sensitized rats was exposed to antigen (ovalbumin). Secretory responses to all three stimuli were suppressed in rats that had previously had colitis. These rats exhibited increased (16-fold) numbers of colonic aerobic bacteria and increased (>3-fold) bacterial translocation, similar to results in rats studied after resolution of enteritis. Postcolitis bacterial translocation was prevented by daily treatment with an inhibitor of inducible nitric oxide synthase. This study demonstrates that intestinal inflammation results in prolonged impairment of colonic epithelial secretion, which may contribute to increases in bacterial load and bacterial translocation. Epithelial dysfunction of this type could underlie an increased propensity for further bouts of inflammation, a hallmark of diseases such as inflammatory bowel disease.

Inhibition of neurogenic inflammation by the Amazonian herbal medicine sangre de grado

This study was designed to determine if the Amazonian medicinal sangre de grado, confers benefit by suppressing the activation of sensory afferent nerves.

METHODS

(i) vasorelaxation of rat mesenteric arteries in response to calcitonin gene-related peptide; (ii) rat paw edema in response to protease- activating peptide receptor 2-activating peptide; (iii) rat paw hyperalgesia in response to low-dose protease-activating peptide receptor 2-activating peptide or prostaglandin E2; (iv) gastric hyperemia in response luminal capsaicin; (v) a clinical trial of a sangre de grado balm in pest control workers. The parent botanical was fractionated for evaluation of potential active components. In preconstricted rat mesenteric arteries, highly diluted sangre de grado (1:10,000) caused a shift to the right of the calcitonin gene-related peptide dose-response curve (p < 0.01). Paw edema in response to protease-activating peptide receptor 2-activating peptide (500 microg) was reduced by as single topical administration sangre de grado balm (1% concentration, p < 0.01) for at least 6 h. Hyperalgesia induced by either low-dose protease-activating peptide receptor 2-activating peptide (50 microg) or prostaglandin E2 was prevented by sangre de grado balm. A fraction possessing analgesic and capsaicin antagonistic properties was isolated and high-performance liquid chromatography and gas chromatography-mass spectrometry analysis indicated that it was a proanthocyandin oligomer. In pest control workers, sangre de grado balm (Zangrado) was preferred over placebo, for the relief of itching, pain, discomfort, edema, and redness in response to wasps, fire ants, mosquitoes, bees, cuts, abrasions, and plant reactions. Subjects reported relief within minutes. We conclude that sangre de grado is a potent inhibitor of sensory afferent nerve mechanisms and supports its ethnomedical use for disorders characterized by neurogenic inflammation.

NO-mesalamine protects colonic epithelial cells against apoptotic damage induced by proinflammatory cytokines

The activation of a self-amplifying cascade of caspases, of which caspase-8 is the apical protease, mediates Fas-, tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL)-, and TNF-alpha-induced apoptosis in colon cell lines. Nitric oxide (NO) protects from apoptosis induced by Fas and TNF-alpha. We examined whether NCX-456, an NO-releasing derivative of mesalamine, protects colon epithelial cells from cytokine-induced apoptosis. Caco-2 and HT-29 cell lines express death factor receptors and are driven to apoptosis in response to incubation with Fas-agonistic antibody, TNF-alpha/interferon-gamma, and TRAIL. The two novel observations reported here are that 1) cotreatment of cells with NCX-456, but not mesalamine, resulted in concentration-dependent protection against death factor-induced apoptosis and inhibition of caspase activity, and 2) exposure to dithiothreitol, an agent that effectively removes NO from thiol groups, resulted in a 70% recovery of caspase activity, which is consistent with S-nitrosation as a major mechanism for caspase inactivation. These data suggest that caspase S-nitrosation represents a mechanism for protection of colonic mucosal epithelial cells from death factor-induced death.

Agonists of proteinase-activated receptor 1 induce plasma extravasation by a neurogenic mechanism

Thrombin, generated in the circulation during injury, cleaves proteinase-activated receptor 1 (PAR1) to stimulate plasma extravasation and granulocyte infiltration. However, the mechanism of thrombin-induced inflammation in intact tissues is unknown. We hypothesized that thrombin cleaves PAR1 on sensory nerves to release substance P (SP), which interacts with the neurokinin 1 receptor (NK1R) on endothelial cells to cause plasma extravasation. PAR1 was detected in small diameter neurons known to contain SP in rat dorsal root ganglia by immunohistochemistry and in situ hybridization. Thrombin and the PAR1 agonist TFLLR-NH(2) (TF-NH(2)) increased [Ca(2+)](i) >50% of cultured neurons (EC(50)s 24 mu ml(-1) and 1.9 microM, respectively), assessed using Fura-2 AM. The PAR1 agonist completely desensitized responses to thrombin, indicating that thrombin stimulates neurons through PAR1. Injection of TF-NH(2) into the rat paw stimulated a marked and sustained oedema. An NK1R antagonist and ablation of sensory nerves with capsaicin inhibited oedema by 44% at 1 h and completely by 5 h. In wild-type but not PAR1(-/-) mice, TF-NH(2) stimulated Evans blue extravasation in the bladder, oesophagus, stomach, intestine and pancreas by 2 - 8 fold. Extravasation in the bladder, oesophagus and stomach was abolished by an NK1R antagonist. Thus, thrombin cleaves PAR1 on primary spinal afferent neurons to release SP, which activates the NK1R on endothelial cells to stimulate gap formation, extravasation of plasma proteins, and oedema. In intact tissues, neurogenic mechanisms are predominantly responsible for PAR1-induced oedema.

Protease-activated receptor-1 stimulates Ca(2+)-dependent Cl(-) secretion in human intestinal epithelial cells

The thrombin receptor, protease-activated receptor-1 (PAR-1), has wide tissue distribution and is involved in many physiological functions. Because thrombin is in the intestinal lumen and mucosa during inflammation, we sought to determine PAR-1 expression and function in human intestinal epithelial cells. RT-PCR showed PAR-1 mRNA expression in SCBN cells, a nontransformed duodenal epithelial cell line. Confluent SCBN monolayers mounted in Ussing chambers responded to PAR-1 activation with a Cl(-)-dependent increase in short-circuit current. The secretory effect was blocked by BaCl2 and the Ca(2+)-ATPase inhibitor thapsigargin, but not by the L-type Ca(2+) channel blocker verapamil or DIDS, the nonselective inhibitor of Ca(2+)-dependent Cl(-) transport. Responses to thrombin and PAR-1-activating peptides exhibited auto- and crossdesensitization. Fura 2-loaded SCBN cells had increased fluorescence after PAR-1 activation, indicating increased intracellular Ca(2+). RT-PCR showed that SCBN cells expressed mRNA for the cystic fibrosis transmembrane conductance regulator (CFTR) and hypotonicity-activated Cl(-) channel-2 but not for the Ca(2+)-dependent Cl(-) channel-1. PAR-1 activation failed to increase intracellular cAMP, suggesting that the CFTR channel is not involved in the Cl(-) secretory response. Our data demonstrate that PAR-1 is expressed on human intestinal epithelial cells and regulates a novel Ca(2+)-dependent Cl(-) secretory pathway. This may be of clinical significance in inflammatory intestinal diseases with elevated thrombin levels.