The airway microbiome of persons with cystic fibrosis correlates with acquisition and microbiological outcomes of incident Stenotrophomonas maltophilia infection.

Rationale: Chronic infection with Stenotrophomonas maltophilia in persons with cystic fibrosis (pwCF) has been linked to an increased risk of pulmonary exacerbations and lung function decline. We sought to establish whether baseline sputum microbiome associates with risk of S. maltophilia incident infection and persistence in pwCF. Methods: pwCF experiencing incident S. maltophilia infections attending the Calgary Adult CF Clinic from 2010-2018 were compared with S. maltophilia-negative sex, age (+/-2 years), and birth-cohort-matched controls. Infection outcomes were classified as persistent (when the pathogen was recovered in ≥50% of cultures in the subsequent year) or transient. We assessed microbial communities from prospectively biobanked sputum using V3-V4 16S ribosomal RNA (rRNA) gene sequencing, in the year preceding (Pre) (n = 57), at (At) (n = 22), and after (Post) (n = 31) incident infection. We verified relative abundance data using S. maltophilia-specific qPCR and 16S rRNA-targeted qPCR to assess bioburden. Strains were typed using pulse-field gel electrophoresis. Results: Twenty-five pwCF with incident S. maltophilia (56% female, median 29 years, median FEV1 61%) with 33 total episodes were compared with 56 uninfected pwCF controls. Demographics and clinical characteristics were similar between cohorts. Among those with incident S. maltophilia infection, sputum communities did not cluster based on infection timeline (Pre, At, Post). Communities differed between the infection cohort and controls (n = 56) based on Shannon Diversity Index (SDI, p = 0.04) and clustered based on Aitchison distance (PERMANOVA, p = 0.01) prior to infection. At the time of incident S. maltophilia isolation, communities did not differ in SDI but clustered based on Aitchison distance (PERMANOVA, p = 0.03) in those that ultimately developed persistent infection versus those that were transient. S. maltophilia abundance within sputum was increased in samples from patients (Pre) relative to controls, measuring both relative (p = 0.004) and absolute (p = 0.001). Furthermore, S. maltophilia abundance was increased in sputum at incident infection in those who ultimately developed persistent infection relative to those with transient infection, measured relatively (p = 0.04) or absolute (p = 0.04), respectively. Conclusion: Microbial community composition of CF sputum associates with S. maltophilia infection acquisition as well as infection outcome. Our study suggests sputum microbiome may serve as a surrogate for identifying infection risk and persistence risk.

A vaping risks education program for school students: Evaluation of the solve mystery toolkit.

One in three grade 7 to 12 students in Canada report trying vaping or e-cigarettes. Despite consequences like nicotine addiction, impaired brain development, increased respiratory symptoms, and association with an increased risk of COVID-19 diagnosis, 48% of youth believe occasional vaping has little to no risk. There is a clear need for youth to learn about vaping consequences. We developed and piloted a novel free interactive educational program on vaping risks which has been used by over 800 grade 7 to 9 students. In post-program surveys, students reported a subjective increase in knowledge about the health consequences of vaping.

Is Canadian federal legislation effective in preventing youth access to vaping initiation products? A study using secret shoppers and online access in three Alberta cities.

The Tobacco and Vaping Products Act (Canada, 1997) (the "TVPA") aims to protect the health of young persons by restricting access to vaping products. We studied whether the TVPA achieves this goal by sending young 'secret shoppers' to 120 shops in Calgary, Edmonton, and Red Deer to attempt to buy nicotine-based vaping-initiation products, and by asking minors to purchase the same product online. We used three 'improper' shop scenarios: 1. a minor or minors; 2. a young adult with no or invalid identification ("ID"); and 3. a young adult with valid ID but clearly buying for an accompanying minor. Of total vendors, 42.5% (51/120) were willing to sell to the young people (p < .001). Most vendors requested ID in all scenarios (97/120, 80.8%). Of these, 28 vendors (28.9% of those requesting ID), were still willing to sell the product. All vendors who did not request ID (23/120, 19.2%) were willing to sell; vape shops were more likely than convenience stores not to request ID (25.4% v. 13.1%). In five online purchase attempts, 60% of deliverers did not meet the TVPA's ID verification requirements. The TVPA does not require packages to reveal their contents; one parent inadvertently signed for the parcel. To prevent youth access, the TVPA should require: a minimum nicotine product purchase age of 21, positive obligations on vendors to request ID, prohibition of sales to adults buying for minors, and that manufacturers disclose the product on posted or delivered parcels. The TVPA should be strictly enforced.

Vitamin D insufficiency and deficiency in pediatric renal transplant recipients.

Vitamin D deficiency is prevalent in the pediatric CKD population. Recognizing that renal transplant recipients have CKD, we assessed the prevalence of vitamin D insufficiency and deficiency in pediatric renal transplant recipients, compared to a healthy pediatric population. We prospectively studied 25(OH)D levels in 29 pediatric renal transplant recipients and 45 control patients over one yr. The overall prevalence of vitamin D insufficiency and deficiency was common in both populations, at 76% (95% CI: 61, 87%) in the pediatric renal transplant recipients and 91% (95% CI: 80, 98%) in the control group. In the paired renal transplant samples, the mean 25(OH)D level was 52.3 ± 17.9 nmol/L in the winter and 65.6 ± 18.8 nmol/L in the summer (95% CI diff.: 3.9, 22.7), in keeping with a significant seasonal difference. The mean dietary intake of vitamin D in the renal transplant recipients, assessed by three-day dietary record, was 5.7 µg/day, with a vitamin D intake below the EAR in the majority. We did not find an association between vitamin D intake and 25(OH)D levels in this study, likely due to the low dietary intake of vitamin D within the transplant population, identifying a potential area for intervention and improvement.

Platelets express functional Toll-like receptor-4.

Profound thrombocytopenia occurs in humans with sepsis and in mice administered lipopolysaccharide (LPS). Growing evidence indicates that platelets may contribute to these abnormalities, but whether that is a direct result of LPS activation of platelets or an indirect result of other inflammatory mechanisms remains unclear. Here we demonstrate that although platelets do not increase P-selectin expression in response to LPS, platelets bind more avidly to fibrinogen under flow conditions in a Toll-like receptor-4 (TLR4)-dependent manner. In addition, we find that CD41+ megakaryocytes grown from fetal livers and adult circulating platelets express significant amounts of TLR4. LPS induced thrombocytopenia in wild-type mice but not in TLR4-deficient (TLR4def) mice. Wild-type platelets accumulated in the lungs of wild-type mice in response to LPS; TLR4def platelets did not. However, wild-type platelets did not accumulate in the lungs of LPS-treated TLR4def mice. Neutrophils also accumulated in the lungs, and this preceded platelet accumulation. Neutrophil depletion completely abolished LPS-induced platelet sequestration into the lungs, but platelet depletion did not affect neutrophil accumulation. Thus, our data show for the first time that platelets do express functional levels of TLR4, which contribute to thrombocytopenia through neutrophil-dependent pulmonary sequestration in response to LPS.

Mast cell-independent mechanisms of immediate hypersensitivity: a role for platelets.

Mast cells have been implicated as the central effectors in allergic responses, yet a fatal anaphylactic response can be induced in mast cell-deficient mice. In this study, we examined the immediate hypersensitivity response in wild-type (WT) and mast cell-deficient mice (W/W(v)) in two different tissues (skin and skeletal muscle). Vascular permeability and leukocyte recruitment were studied after immediate challenge or 4 h postchallenge in OVA-sensitized mice. In skin, immediate challenge induced a significant increase in vascular permeability (75%) within 30 min and was accompanied by increased leukocyte adhesion 4 h postchallenge. In the absence of mast cells, no changes in vascular permeability or leukocyte recruitment were observed in skin. In WT skeletal muscle, immediate challenge induced a rapid increase (80%) in vascular permeability within 5 min and significant leukocyte recruitment after 4 h. Surprisingly, in W/W(v), a gradual increase in vascular permeability was observed, reaching a maximum (50%) within 30 min. Despite the absence of mast cells, subsequent leukocyte emigration was similar to that observed in WT mice. Pretreatment with anti-platelet serum in W/W(v) returned Ag-induced vascular permeability and leukocyte recruitment to baseline. Platelets were shown to interact with endothelium in skeletal muscle, but not dermal microvasculature. These data illustrate that mast cells play a prominent role in vascular permeability and leukocyte recruitment in skin in response to Ag, however, in skeletal muscle; these changes can occur in the absence of mast cells, and are mediated, in part, by the presence of platelets.