Responsive Feeding Practices to Promote Healthy Diets: A Mixed Method Study among Low-Income Caregivers with Toddlers.

Responsive feeding (RF), the reciprocal feeding approach between caregiver and child that promotes child health, is understudied among low-income caregivers. This mixed methods study with low-income caregivers of 12-to-36-month-olds aimed to (1) assess variability in RF and associations with children's dietary intake, and (2) explore caregivers' perceptions of RF. Caregivers (n = 134) completed an online survey with RF questions (n = 25), grouped into environmental (meal environment, caregiver modeling, caregiver beliefs) and child (self-regulation, hunger/satiety cues, food for reward, food acceptance) influences scores. Children's recent food group consumption was loaded onto healthy and less healthy intake scores. In an adjusted multiple linear regression analysis, greater RF scores for environmental and child influences were associated with greater healthy intake scores (p's < 0.01). Greater scores for environmental influences were also associated with lower scores for unhealthy intake (p < 0.01). From focus groups with a separate sample of caregivers (n = 24), thematic analysis uncovered that two themes aligned (trust in child cues, positive strategies to encourage children to eat non-preferred foods) and two misaligned (lack of trust in child cues, use of force/bribery) with RF. Complementary integration of quantitative and qualitative findings can inform future interventions with low-income caregivers, encouraging trust in young children's hunger/satiety cues and positive strategies for food acceptance to improve diet quality.

Representation Matters: One Urology Residency Program's Approach to Increasing Workforce Diversity.

OBJECTIVE: To address the challenge in urology in recruiting physicians from backgrounds racially and ethnically underrepresented in medicine (URiM), we sought to design, implement, and evaluate methods for recruiting URiM candidates to our urology residency program. METHODS: We developed a 3-pronged approach aimed at increasing the number of interviewed applicants, and subsequently number of URiM residents recruited to our program. The 3 facets included: (1) funded visiting student rotation, (2) holistic evaluation of applications, (3) implemented targeted outreach. Statistical analysis of the applicants interviewed and matched into our residency program, as well as traditional metrics used for residency recruitment, were performed from 2015 to 2022. RESULTS: The number of URiM interviewees significantly increased from 6.1% in 2015 to its peak, 40%, in 2020. In 2015, there were no URiM residents in our urology residency program. By 2022, the total URiM complement increased to 35%. In evaluating traditional metrics of residency recruitment, there was no significant difference in mean USMLE Step 1 score before compared with after the implementation of our recruitment approach. The maximum rank number reached to fill the urology residency positions also remained relatively stable throughout the study period, with a range from 5 to 38. CONCLUSION: We demonstrate that the implementation of our innovative and intentional 3-pronged recruitment approach effectively increased the number of URiM interviewees and residents in our residency program. The diversification of our urology workforce depends on the implementation of such efforts, and we encourage urologists to lead the way on such initiatives.

Music therapy in pediatric asthma improves pulmonary function while reducing hospitalizations.

Objective: The aim of this study was to evaluate music therapy (MT), in conjunction with standard care, as a complementary option for asthma management in pediatric patients.Methods: 173 children were randomly assigned to one of three groups: 1) Music: a single individualized MT session along with a recorder and journal with instructions for home use; 2) Music Plus: weekly group MT sessions along with a recorder and journal for home use; or 3) Control: standard of care. Primary endpoints included pulmonary function tests (FEV1, FVC, FEF25-75, PEF), hospitalizations, ER visits, missed school days, and quality of life (Juniper).Results: Significant intergroup differences relative to Controls were observed for FEV1/FVC (Music and Music Plus, p < 0.05) and FEF25-75 (Music Plus; p < 0.01). Music Plus participants experienced fewer hospitalizations compared to Controls (p < 0.001), corresponding to 1.16 fewer hospitalizations per patient-year. Caregivers' perception of their children's QOL significantly increased in the Music (p = 0.011) and Music Plus (p < 0.001) groups compared to Controls.Conclusion: These results reflect MT's potential to favorably impact pediatric asthma management as a child-friendly, low-risk intervention. Further research is needed to substantiate the possible benefits of incorporating MT into standard treatment regimens.

Opportunities for use of one species for longer-term toxicology testing during drug development: A cross-industry evaluation.

An international expert working group representing 37 organisations (pharmaceutical/biotechnology companies, contract research organisations, academic institutions and regulatory bodies) collaborated in a data sharing exercise to evaluate the utility of two species within regulatory general toxicology studies. Anonymised data on 172 drug candidates (92 small molecules, 46 monoclonal antibodies, 15 recombinant proteins, 13 synthetic peptides and 6 antibody-drug conjugates) were submitted by 18 organisations. The use of one or two species across molecule types, the frequency for reduction to a single species within the package of general toxicology studies, and a comparison of target organ toxicities identified in each species in both short and longer-term studies were determined. Reduction to a single species for longer-term toxicity studies, as used for the development of biologicals (ICHS6(R1) guideline) was only applied for 8/133 drug candidates, but might have been possible for more, regardless of drug modality, as similar target organ toxicity profiles were identified in the short-term studies. However, definition and harmonisation around the criteria for similarity of toxicity profiles is needed to enable wider consideration of these principles. Analysis of a more robust dataset would be required to provide clear, evidence-based recommendations for expansion of these principles to small molecules or other modalities where two species toxicity testing is currently recommended.

The Physician's Role in Responding to Existential Suffering: What Does It Mean to Comfort Always?

Existential suffering is commonly experienced by patients with serious medical illnesses despite the advances in the treatment of physical and psychological symptoms that often accompany incurable diseases. Palliative care (PC) clinicians wishing to help these patients are faced with many barriers including the inability to identify existential suffering, lack of training in how to address it, and time constraints. Although mental health and spiritual care providers play an instrumental role in addressing the existential needs of patients, PC clinicians are uniquely positioned to coordinate the necessary resources for addressing existential suffering in their patients. With this article, we present a case of a patient in existential distress and a framework to equip PC clinicians to assess and address existential suffering.

Integrating HIV care and treatment into tuberculosis clinics in Lusaka, Zambia: results from a before-after quasi-experimental study.

BACKGROUND: Patients with HIV-associated tuberculosis (TB) often have their TB and HIV managed in separate vertical programs that offer care for each disease with little coordination. Such "siloed" approaches are associated with diagnostic and treatment delays, which contribute to unnecessary morbidity and mortality. To improve TB/HIV care coordination and early ART initiation, we integrated HIV care and treatment into two busy TB clinics in Zambia. We report here the effects of our intervention on outcomes of linkage to HIV care, early ART uptake, and TB treatment success for patients with HIV-associated TB in Lusaka, Zambia. METHODS: We provided integrated HIV treatment and care using a "one-stop shop" model intervention. All new or relapse HIV-positive TB patients were offered immediate HIV program enrolment and ART within 8 weeks of anti-TB therapy (ATT) initiation. We used a quasi-experimental design, review of routine program data, and survival analysis and logistic regression methods to estimate study outcomes before (June 1, 2010-January 31, 2011) and after (August 1, 2011-March 31, 2012) our intervention among 473 patients with HIV-associated TB categorized into pre- (n = 248) and post-intervention (n = 225) cohorts. RESULTS: Patients in the pre- and post-intervention cohorts were mostly male (60.1% and 52.9%, respectively) and young (median age: 33 years). In time-to-event analyses, a significantly higher proportion of patients in the post-intervention cohort linked to HIV care by 4 weeks post-ATT initiation (53.9% vs. 43.4%, p = 0.03), with median time to care linkage being 59 and 25 days in the pre- and post-intervention cohorts, respectively. In Cox proportional hazard modelling, patients receiving the integration intervention started ART by 8 weeks post-ATT at 1.33 times the rate (HR = 1.33, 95% CI: 1.00-1.77) as patients pre-intervention. In logistic regression modelling, patients receiving the intervention were 2.02 times (95% CI: 1.11-3.67) as likely to have a successful TB treatment outcome as patients not receiving the intervention. CONCLUSIONS: Integrating HIV treatment and care services into routine TB clinics using a one-stop shop model increased linkage to HIV care, rates of early ART initiation, and TB treatment success among patients with HIV-associated TB in Lusaka, Zambia.

A Fully Automated High-Throughput Flow Cytometry Screening System Enabling Phenotypic Drug Discovery.

The goal of high-throughput screening is to enable screening of compound libraries in an automated manner to identify quality starting points for optimization. This often involves screening a large diversity of compounds in an assay that preserves a connection to the disease pathology. Phenotypic screening is a powerful tool for drug identification, in that assays can be run without prior understanding of the target and with primary cells that closely mimic the therapeutic setting. Advanced automation and high-content imaging have enabled many complex assays, but these are still relatively slow and low throughput. To address this limitation, we have developed an automated workflow that is dedicated to processing complex phenotypic assays for flow cytometry. The system can achieve a throughput of 50,000 wells per day, resulting in a fully automated platform that enables robust phenotypic drug discovery. Over the past 5 years, this screening system has been used for a variety of drug discovery programs, across many disease areas, with many molecules advancing quickly into preclinical development and into the clinic. This report will highlight a diversity of approaches that automated flow cytometry has enabled for phenotypic drug discovery.

Child-targeted fast-food television advertising exposure is linked with fast-food intake among pre-school children.

OBJECTIVE: To determine whether exposure to child-targeted fast-food (FF) television (TV) advertising is associated with children's FF intake in a non-experimental setting. DESIGN: Cross-sectional survey conducted April-December 2013. Parents reported their pre-school child's TV viewing time, channels watched and past-week FF consumption. Responses were combined with a list of FF commercials (ads) aired on children's TV channels during the same period to calculate children's exposure to child-targeted TV ads for the following chain FF restaurants: McDonald's, Subway and Wendy's (MSW). SETTING: Paediatric and Women, Infants, and Children (WIC) clinics in New Hampshire, USA. SUBJECTS: Parents (n 548) with a child of pre-school age. RESULTS: Children's mean age was 4·4 years; 43·2 % ate MSW in the past week. Among the 40·8 % exposed to MSW ads, 23·3 % had low, 34·2 % moderate and 42·5 % high exposure. McDonald's accounted for over 70 % of children's MSW ad exposure and consumption. Children's MSW consumption was significantly associated with their ad exposure, but not overall TV viewing time. After adjusting for demographics, socio-economic status and other screen time, moderate MSW ad exposure was associated with a 31 % (95 % CI 1·12, 1·53) increase and high MSW ad exposure with a 26 % (95 % CI 1·13, 1·41) increase in the likelihood of consuming MSW in the past week. Further adjustment for parent FF consumption did not change the findings substantially. CONCLUSIONS: Exposure to child-targeted FF TV advertising is positively associated with FF consumption among children of pre-school age, highlighting the vulnerability of young children to persuasive advertising and supporting recommendations to limit child-directed FF marketing.

Temperature induces significant changes in both glycolytic reserve and mitochondrial spare respiratory capacity in colorectal cancer cell lines.

Thermotherapy, as a method of treating cancer, has recently attracted considerable attention from basic and clinical investigators. A number of studies and clinical trials have shown that thermotherapy can be successfully used as a therapeutic approach for various cancers. However, the effects of temperature on cancer bioenergetics have not been studied in detail with a real time, microplate based, label-free detection approach. This study investigates how changes in temperature affect the bioenergetics characteristics (mitochondrial function and glycolysis) of three colorectal cancer (CRC) cell lines utilizing the Seahorse XF96 technology. Experiments were performed at 32°C, 37°C and 42°C using assay medium conditions and equipment settings adjusted to produce equal oxygen and pH levels ubiquitously at the beginning of all experiments. The results suggest that temperature significantly changes multiple components of glycolytic and mitochondrial function of all cell lines tested. Under hypothermia conditions (32°C), the extracellular acidification rates (ECAR) of CRC cells were significantly lower compared to the same basal ECAR levels measured at 37°C. Mitochondrial stress test for SW480 cells at 37°C vs 42°C demonstrated increased proton leak while all other OCR components remained unchanged (similar results were detected also for the patient-derived xenograft cells Pt.93). Interestingly, the FCCP dose response at 37°C vs 42°C show significant shifts in profiles, suggesting that single dose FCCP experiments might not be sufficient to characterize the mitochondrial metabolic potential when comparing groups, conditions or treatments. These findings provide valuable insights for the metabolic and bioenergetic changes of CRC cells under hypo- and hyperthermia conditions that could potentially lead to development of better targeted and personalized strategies for patients undergoing combined thermotherapy with chemotherapy.

Doxycycline administration improves fascial interface in hernia repair.

BACKGROUND: Despite improvements in ventral hernia repair techniques, their recurrence rates are unacceptably high. Increased levels of matrix metalloproteinases (MMPs) and reduced collagen-1 to -3 ratios are implicated in incisional hernia formation. We have recently shown doxycycline treatment for 4 wk after hernia repair reduced MMP levels, significantly increased collagen-1 to -3 ratios, and increased tensile strength of repaired interface fascia. However, this increase was not statistically significant. In this study, we extended treatment duration to determine whether this would impact the tensile strength of the repaired interface fascia. MATERIALS AND METHODS: Thirty-two male Sprague-Dawley rats underwent incision hernia creation and subsequent repair with polypropylene mesh. The animals received either saline (n = 16) or doxycycline (n = 16) beginning from 1 day before hernia repair until the end of survival time of 6 wk (n = 16) or 12 wk (n = 16). Tissue samples were investigated for MMPs and collagen subtypes using Western blot procedures, and tensiometric analysis was performed. RESULTS: At both 6 and 12 wk after hernia repair, the tensiometric strength of doxycycline-treated mesh to fascia interface (MFI) tissue showed a statistically significant increase when compared with untreated control MFI. In both groups, collagen-1, -2, and -3 ratios were remarkably increased in doxycycline-treated MFI. At 6 wk, the doxycycline-treated MFI group showed a significant decrease in MMP-2, an increase in MMP-3, and no change in MMP-9. At 12 wk, MMP-9 showed a remarkable reduction, whereas MMP-2 and -3 protein levels increased in the doxycycline-treated MFI group. CONCLUSIONS: Doxycycline administration results in significantly improved strength of repaired fascial interface tissue along with a remarkable increase in collagen-1, -2, and -3 ratios.

The Smart Choices front-of-package nutrition label. Influence on perceptions and intake of cereal.

Numerous front-of-package (FOP) nutrition labeling systems exist, but it is unclear if such labels influence behavior. A single-summary label called Smart Choices (SC) appeared briefly on products in the United States in 2009. The current study aimed to evaluate (1) the influence the SC symbol has on the serving and consumption of cereal; and (2) the impact of providing calorie and serving size information on a FOP label. Two hundred and sixteen adults were randomized to a high-sugar breakfast cereal that had either (1) no label; (2) the SC symbol; or (3) a modified SC symbol with serving size information. Participants rated perceptions of healthfulness, taste, and purchase intent, estimated calories per serving and poured and ate the cereal for breakfast. Participants in the SC label conditions were better able to estimate calories per serving, but there were no differences across groups on perceptions of healthfulness, taste, purchase intent, and levels of vitamins, and sugar or amount of cereal poured or consumed. These results suggest that calories per serving information on FOP labels can increase knowledge, but the SC symbol had little impact on behavior. Studies examining FOP label influence on purchasing, consumption, and product reformulation are greatly needed to determine label utility.

Testing two types of self-help CBT-I for insomnia in older adults with arthritis or coronary artery disease.

OBJECTIVE: The present study tested two methods of self-help cognitive-behavioral therapy for insomnia (CBT-I) for 106 older adults (mean age = 68) with osteoarthritis (n = 33) or coronary artery disease (n = 33) or no significant medical condition (n = 40). The latter was employed as a comparison group to test the differential efficacy between primary and comorbid insomnia. METHOD: Self-help CBT-I has demonstrated efficacy in previous studies, so two treatments were compared rather than employing a no treatment control group. Participants were randomly assigned to a book version or an enhanced multimedia version of CBT-I. RESULTS: Both versions of CBT-I demonstrated efficacy in improving all measures of sleep at posttreatment, using intent-to-treat analyses. These sleep improvements were maintained among 86 treatment completers who participated in 1-year follow-up assessment. There were no significant differences in treatment response between primary (no medical condition) and comorbid insomnia participants and no significant differences between the two types of self-help according to sleep log measure. However, multimedia participants compared to book participants showed more improvement on three global sleep measures administered at posttreatment only. CONCLUSIONS: Although outcomes were attenuated relative to those obtained in therapist led intervention studies, the results suggest that self-help CBT-I has good potential to serve as a first-line, cost-effective treatment for both primary and comorbid insomnia in older adults.

Nutrition-related claims on children's cereals: what do they mean to parents and do they influence willingness to buy?

OBJECTIVE: To examine parents' beliefs about the meaning of common front-of-package nutrition-related claims on children's cereals and determine whether the claims would make them more willing to buy the cereals. DESIGN: Parents viewed images of box fronts for children's cereals of below-average nutritional quality, as assessed by a validated nutrient profiling model. These boxes featured various nutrition-related claims including 'supports your child's immunity', 'whole grain', 'fibre', 'calcium and vitamin D' and 'organic'. Participants were provided possible meanings for these claims and asked to select any that applied with the option to write in additional meanings. They also indicated how the claim would affect their willingness to buy the product. SETTING: Online survey. SUBJECTS: Parents with children between the ages of 2 and 11 years (n 306) recruited through an online panel. RESULTS: The majority of parents misinterpreted the meaning of claims commonly used on children's cereals. They inferred that cereals with claims were more nutritious overall and might provide specific health-related benefits for their children; and these beliefs predicted greater willingness to buy the cereals. CONCLUSIONS: These findings indicate that common front-of-package nutrition-related claims are potentially misleading, especially when placed on products with high levels of nutrients to limit (e.g. sugar, sodium) and low levels of other nutrients to encourage (e.g. fibre, protein). Additional regulation is needed to protect consumers in the USA.

Substrate- and species-dependent inhibition of P-glycoprotein-mediated transport: implications for predicting in vivo drug interactions.

P-glycoprotein (P-gp)-based drug interactions are a major concern in the clinic and in preclinical drug development, especially with respect to the intestinal absorption of drugs and distribution of drugs across the blood-brain barrier. Thus, there is significant interest in developing in vitro (e.g., cell culture) and in vivo models (e.g., rodents) to predict such interactions. In order to generate accurate predictions from these models, however, an understanding of the magnitude of substrate- and species-dependent differences in P-gp inhibition is required. We have used a sensitive flow cytometry assay to measure the ability of various drugs to inhibit the initial rate of accumulation of two fluorescent drug analogs (probe substrates), 4,4-difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-s -indacene (BODIPY)-verapamil and BODIPY-prazosin, into Lewis lung carcinoma-porcine kidney 1 (LLC-PK1) cells expressing human or rat P-gp. The inhibition of P-gp-mediated efflux of these two fluorescent substrates by several drugs, including quinidine and itraconazole, was found to be substrate- and/or species-dependent. These data suggest that to provide accurate prediction of clinically significant P-gp drug interactions, multiple P-gp substrates will need to be used in both in vitro and in vivo (including human) drug interaction studies. In addition, extrapolation of P-gp-based drug interaction in rodents to humans must be conducted with caution.

Effects of progressive muscle relaxation training on nociceptive flexion reflex threshold in healthy young adults: a randomized trial.

Although prior studies have demonstrated effects of progressive muscle relaxation (PMR) in reducing self-reported pain, no laboratory studies have examined the effects of PMR on objective indicators of descending modulation of nociception. This randomized controlled study utilized the nociceptive flexion reflex (NFR) to evaluate nociceptive responding among 55 college-age men and women (mean age=19.4+/-1.2 years). Participants completed laboratory assessments of NFR threshold and questionnaires evaluating pain and stress. Participants were then randomly assigned to either a 25-min PMR condition or a no-treatment control condition. Following the brief intervention, participants completed a second NFR procedure and self-report questionnaires. Results indicated a significant time by condition interaction for NFR, with participants in the PMR condition experiencing a significant increase in NFR threshold while participants in the no-treatment condition experienced no change in NFR. Ratings of pain did not change during the study, but PMR participants reported decreased stress following the PMR intervention. This is the first study with a randomized no-treatment control group demonstrating the effect of a brief PMR protocol on descending inhibition of nociception. Results support the efficacy of PMR in reducing nociceptive response and provide further evidence of the utility of behavioral pain management strategies.

Serum omega-3 fatty acids are associated with variation in mood, personality and behavior in hypercholesterolemic community volunteers.

Low dietary intake of omega-3 polyunsaturated fatty acids has been linked to several features of psychiatric symptomatology, including depression, disorders of impulse control, and hostility. Preliminary intervention trials of omega-3 fatty acid supplementation for clinical depression and other disorders have reported benefit. However, few studies have investigated the relationships between these fatty acids and normative variability in mood, behavior and personality. Participants were 105 hypercholesterolemic, but otherwise healthy, non-smoking adults. Fasting serum alpha-linolenic (alpha-LNA), eicosapentaenoic (EPA) and docosahexaenoic acid (DHA) were assayed with gas chromatography. Participants completed the Beck Depression Inventory (BDI), the NEO Five Factor Personality Inventory (NEO-FFI) and the Barratt Impulsiveness Scale (BIS). In multivariate analyses, higher levels of the long chain omega-3 PUFAs, EPA and DHA, were associated with significantly reduced odds of scoring >or=10 on the BDI. Similarly, DHA and EPA covaried inversely with NEO-Neuroticism scores, whereas DHA was positively associated with NEO-Agreeableness. On the BIS, DHA was inversely related to cognitive impulsivity and alpha-LNA was inversely related to motor and total impulsivity. These findings suggest that omega-3 fatty acid status is associated with variability in affect regulation, personality and impulse control.

Use, appropriateness, and diagnostic yield of screening colonoscopy: an international observational study (EPAGE).

BACKGROUND: Screening for colorectal cancer (CRC) has been shown to decrease mortality. OBJECTIVE: To examine determinants associated with having (1) a screening colonoscopy, (2) an appropriate indication for screening, and (3) a significant diagnosis at screening. DESIGN: Prospective observational study. SETTING: Twenty-one endoscopy centers from 11 countries. PATIENTS: Asymptomatic patients who underwent a colonoscopy for the purpose of detecting CRC and who did not have a history of polyps or CRC, a lesion observed at a recent barium enema or sigmoidoscopy, or a recent positive fecal occult blood test. INTERVENTION: Screening colonoscopy. MAIN OUTCOME MEASUREMENTS: Appropriateness according to the European Panel on the Appropriateness of Gastrointestinal Endoscopy (EPAGE) criteria and significant diagnoses (cancer, adenomatous polyps, new diagnoses of inflammatory bowel disease, angiodysplasia). RESULTS: Of 5069 colonoscopies, 561 (11%) were performed for screening purposes. Patients were more likely to have a screening colonoscopy if they were aged 45 to 54 years (odds ratio [OR] 2.53, 95% confidence interval [CI] 1.60-3.99). Screening colonoscopies were appropriate, uncertain, and inappropriate in 26%, 60%, and 14% of cases, respectively. Eighty-one significant diagnoses were made, including 4 cancers. Significant diagnoses were more often made for uncertain/appropriate indications (OR 3.20, 95% CI 1.12-9.17) than for inappropriate indications. LIMITATIONS: Although data completeness was asked of all centers, it is possible that not all consecutive patients were included. Participating centers were a convenience sample and thus may not be representative. CONCLUSIONS: About 1 of 10 colonoscopies were performed for screening, preferentially in middle-aged individuals. A higher diagnostic yield in uncertain/appropriate indications suggests that the use of appropriateness criteria may enhance the efficient use of colonoscopy for screening.

Biochemical characterization of prostasin, a channel activating protease.

Human prostasin was recently identified as a potential regulator of epithelial sodium channel (ENaC) function. Through the use of positional scanning combinatorial substrate libraries, prostasin was shown to have a preference for poly-basic substrates: in position P4 preference was for arginine or lysine; in P3 preference was for histidine, lysine or arginine; in P2 preference was for basic or large hydrophobic amino acids; and in P1 preference was for arginine and lysine. P1', P2', and P3' displayed broad selectivity with the exception of a lack of activity for isoleucine, and P4' had a preference for small, unbranched, amino acids such as alanine and serine. A prostasin-preferred poly-basic cleavage site was found in the extracellular domains of the ENaC alpha- and beta-subunits, and may present a mechanism for prostasin activation. The absence of activity seen with substrates containing isoleucine in position P1' explains the inability of prostasin to autoactivate and suggests that prostasin proteolytic activity is regulated by an upstream protease. Prostasin activity was highly influenced by mono- and divalent metal ions which were potent inhibitors and substrate specific modulators of enzymatic activity. In the presence of sub-inhibitory concentrations of zinc, the activity of prostasin increased several-fold and its substrate specificity was significantly altered in favor of a strong preference for histidine in positions P3 or P4 of the substrate.

Modulation of leukotriene B4 receptor-1 expression by dexamethasone: potential mechanism for enhanced neutrophil survival.

Glucocorticoids can down-regulate many inflammatory and immune responses and constitute a powerful therapeutic tool in a number of diseases. However, they have a somewhat paradoxical effect on neutrophils, in that they prolong their survival. Because leukotriene B(4) (LTB(4)) can also extend neutrophil survival, we proposed that glucocorticoids could prevent neutrophil apoptosis by up-regulating their expression of the high-affinity LTB(4) receptor (BLT1). Here we show that, indeed, dexamethasone (DEX) up-regulates the steady-state levels of BLT1 mRNA in human neutrophils. The effect was time and concentration dependent, being maximal at 4 h and at 10-100 nM DEX. The effect was also dependent on transcriptional activity, whereas BLT1 mRNA stability was not affected. DEX-induced up-regulation of BLT1 expression was prevented by pretreatment with the LTB(4) antagonist LY255283. Moreover, LTB(4) itself up-regulated the expression of BLT1 mRNA. BLT1 protein expression on neutrophils exposed to DEX for 24 h was also up-regulated 2- to 3-fold, and DEX-treated as well as LTB(4)-treated cells showed enhanced responsiveness to LTB(4) in terms of intracellular Ca(2+) mobilization and chemotaxis. Whereas DEX and LTB(4) alone decreased neutrophil apoptosis by approximately 50%, neutrophils treated with both LTB(4) and DEX showed >90% survival at 24 h. Moreover, BLT1 antagonists prevented the increased neutrophil survival induced by DEX as well as by LTB(4). Taken together, our results suggest that DEX-induced up-regulation of BLT1 expression in neutrophils may be one mechanism through which glucocorticoids can prolong neutrophil survival, namely by enhancing cell responses to the antiapoptotic effect of LTB(4).