Hypoxia-inducible factor-1α inhibition modulates airway hyperresponsiveness and nitric oxide levels in a BALB/c mouse model of asthma.

Hypoxia-inducible factor (HIF)-1α is a master regulator of inflammation and is upregulated in alveolar macrophages and lung parenchyma in asthma. HIF-1α regulates select pathways in allergic inflammation, and thus may drive particular asthma phenotypes. This work examines the role of pharmacologic HIF-1α inhibition in allergic inflammatory airway disease (AIAD) pathogenesis in BALB/c mice, which develop an airway hyperresponsiveness (AHR) asthma phenotype. Systemic treatment with HIF-1α antagonist YC-1 suppressed the increase in HIF-1α expression seen in control AIAD mice. Treatment with YC-1 also decreased AHR, blood eosinophilia, and allergic inflammatory gene expression: IL-5, IL-13, myeloperoxidase and iNOS. AIAD mice had elevated BAL levels of NO, and treatment with YC-1 eliminated this response. However, YC-1 did not decrease BAL, lung or bone marrow eosinophilia. We conclude that HIF-1α inhibition in different genetic backgrounds, and thus different AIAD phenotypes, decreases airway resistance and markers of inflammation in a background specific manner. CAPSULE SUMMARY: Asthma is a common disease that can be difficult to control with current therapeutics. We describe how pharmacologic targeting of a specific transcription factor, HIF-1α, suppresses asthmatic airway reactivity and inflammation.

Is it time to end race and ethnicity adjustment for pediatric pulmonary function tests?

The continued inclusion of race in spirometry reference equations is a topic of intense debate for adult lung function, but less discussion has focused on implications for children. Obtaining accurate estimates of children's lung function is an important component of the diagnosis of childhood respiratory illnesses, including asthma, cystic fibrosis, and interstitial lung disease. Given the higher burden among racial/ethnic minorities for many respiratory illnesses, it is critical to avoid racial bias in interpreting lung function. We recommend against the continued use of race-specific reference equations for a number of reasons. The original reference populations used to develop the equations were comprised of children with restricted racial diversity, relatively small sample sizes, and likely included some unhealthy children. Moreover, there is no scientific justification for innate racial differences in lung function, as there is no clear physiological or genetic explanation for the disparities. Alternatively, many environmental factors harm lung development, including allergens from pests, asbestos, lead, prenatal smoking, and air pollution, as well as preterm birth and childhood respiratory illnesses, which are all more common among minority racial groups. Race-neutral equations may provide a temporary solution, but still rely on the racial diversity of the reference populations used to build them. Ultimately researchers must uncover the underlying factors truly driving racial differences in lung function.

Bacteriophage Therapy of Multidrug-resistant Achromobacter in an 11-Year-old Boy With Cystic Fibrosis Assessed by Metagenome Analysis.

BACKGROUND: Cystic fibrosis (CF) is a genetic disease associated with lung disease characterized by chronic pulmonary infection, increasingly caused by multiple drug-resistant pathogens after repeated antibiotic exposure, limiting antibiotic treatment options. Bacteriophages can provide a pathogen-specific bactericidal treatment used with antibiotics to improve microbiologic and clinical outcomes in CF. METHODS: Achromobacter species isolates from sputum of a chronically infected person with CF, were assessed for susceptibility to bacteriophages: 2 highly active, purified bacteriophages were administered intravenously every 8 hours, in conjunction with a 14-day piperacillin/tazobactam course for CF exacerbation. Sputum and blood were collected for metagenome analysis during treatment, with sputum analysis at 1-month follow-up. Assessments of clinical status, pulmonary status and laboratory evaluation for safety were conducted. RESULTS: Bacteriophage administration was well-tolerated, with no associated clinical or laboratory adverse events. Metagenome analysis documented an 86% decrease in the relative proportion of Achromobacter DNA sequence reads in sputum and a 92% decrease in blood, compared with other bacterial DNA reads, comparing pretreatment and posttreatment samples. Bacteriophage DNA reads were detected in sputum after intravenous administration during treatment, and at 1-month follow-up. Reversal of antibiotic resistance to multiple antibiotics occurred in some isolates during treatment. Stabilization of lung function was documented at 1-month follow-up. CONCLUSIONS: Bacteriophage/antibiotic treatment decreased the host pulmonary bacterial burden for Achromobacter assessed by metagenome analysis of sputum and blood, with ongoing bacteriophage replication documented in sputum at 1-month follow-up. Prospective controlled studies are needed to define the dose, route of administration and duration of bacteriophage therapy for both acute and chronic infection in CF.

Leveraging Electronic Health Records for Guideline-Based Asthma Documentation.

BACKGROUND: Asthma is the most common pediatric chronic disease; thus, clinical guidelines have been developed for its assessment and management, which rely on systematic symptom documentation. Electronic health records (EHR) have the potential to record clinical data systematically; however, variability in documentation persists. OBJECTIVE: To identify if the use of a structured asthma template is associated with increased guideline-based asthma documentation and clinical outcomes when compared with the use of nonstructured ones. METHODS: We performed a retrospective case-control study comparing the use of nonstructured templates (NSTs) and asthma-structured templates (ASTs) in new patient and first follow-up encounters, evaluated by pediatric pulmonologists between March 2016 and December 2021. Asthma history items were selected following clinical guidelines, summarized in 29 items for new and 22 items for follow-up encounters. Associations with demographic, spirometry, and health care utilization were explored. RESULTS: A total of 546 initial encounters were included; 450 used structured templates. The use of an AST was associated with higher documentation of asthma items in initial and follow-up encounters. Linear regression analysis showed that the use of ASTs was associated with a 28.2% and 39.65% increase in asthma history completeness (in initial and follow-up encounters, respectively), compared with the use of NSTs. AST use was associated with higher rates of systemic steroid prescriptions within 12 months. No other differences were observed after adjusting for asthma severity. CONCLUSIONS: Using asthma-specific structured templates was associated with increased guideline-based asthma documentation. Leveraging the EHR as a clinical and research tool has the potential to improve clinical practice.

Bicarbonate Effects on Antibacterial Immunity and Mucus Glycobiology in the Cystic Fibrosis Lung: A Review With Selected Experimental Observations.

The primary defect in cystic fibrosis (CF) is abnormal chloride and bicarbonate transport in the cystic fibrosis transmembrane conductance regulator (CFTR) epithelial ion channel. The apical surface of the respiratory tract is lined by an airway surface liquid layer (ASL) composed of mucin comprising mainly MUC5A and MUC5B glycoproteins. ASL homeostasis depends on sodium bicarbonate secretion into the airways and secretion deficits alter mucus properties leading to airway obstruction, inflammation, and infections. Downstream effects of abnormal ion transport in the lungs include altered intrinsic immune defenses. We observed that neutrophils killed Pseudomonas aeruginosa more efficiently when it had been exposed to sodium bicarbonate, and formation of neutrophil extracellular traps (NETs) by neutrophils was augmented in the presence of increasing bicarbonate concentrations. Physiological levels of bicarbonate sensitized P. aeruginosa to the antimicrobial peptide cathelicidin LL-37, which is present in both lung ASL and in NETs. Sodium bicarbonate has various uses in clinical medicine and in the care of CF patients, and could be further explored as a therapeutic adjunct against Pseudomonas infections.

Persistent recovery of pancreatic function in patients with cystic fibrosis after ivacaftor.

Exocrine pancreatic insufficiency (EPI), which leads to malabsorption and poor weight gain, is seen in 85% of patients with cystic fibrosis (CF). EPI is treated with pancreatic enzyme replacement therapy taken with each meal. The highly effective cystic fibrosis transmembrane conductance regulator (CFTR) modulator, ivacaftor, restores CFTR function in patients with responsive mutations. It is a widely held view that EPI in CF is irreversible due to the complete destruction of pancreatic ducts and acinar cells. We describe three pediatric CF patients with EPI who were started on ivacaftor, and subsequently showed evidence of restored exocrine pancreatic function with clinical and biochemical parameters.

Putting the model to the test: are APC proteins essential for neuronal polarity, axon outgrowth, and axon targeting?

The highly polarized architecture of neurons is important for their function. Experimental data based on dominant-negative approaches suggest that the tumor suppressor adenomatous polyposis coli (APC), a regulator of Wnt signaling and the cytoskeleton, regulates polarity of neuroectodermal precursors and neurons, helping specify one neurite as the axon, promoting its outgrowth, and guiding axon pathfinding. However, such dominant-negative approaches might affect processes in which APC is not essential. We completely removed both APCs from Drosophila melanogaster larval neural precursors and neurons, testing whether APCs play universal roles in neuronal polarity. Surprisingly, APCs are not essential for asymmetric cell division or the stereotyped division axis of central brain (CB) neuroblasts, although they do affect cell cycle progression and spindle architecture. Likewise, CB, lobular plug, and mushroom body neurons do not require APCs for polarization, axon outgrowth, or, in the latter two cases, axon targeting. These data suggest that proposed cytoskeletal roles for APCs in mammals should be reassessed using loss of function tools.

Novel roles for APC family members and Wingless/Wnt signaling during Drosophila brain development.

Construction of the brain is one of the most complex developmental challenges. Wnt signals shape all tissues, including the brain, and the tumor suppressor adenomatous polyposis coli (APC) is a key negative regulator of Wnt/Wingless (Wg) signaling. We carried out the first assessment of the role of APC proteins in brain development, simultaneously inactivating both APC1 and APC2 in clones of cells in the Drosophila larval optic lobe. We focused on the medulla, where epithelial neural progenitors shift from symmetric to asymmetric divisions across the lateral-medial axis. Loss of both APCs triggers dramatic defects in optic lobe development. Double mutant cells segregate from wild-type neighbors, while double mutant neurons form tangled axonal knots, suggesting changes in cell adhesion. Strikingly, phenotypes are graded along the anterior-posterior axis. Activation of Wg signaling downstream of APC mimics these phenotypes, a dominant-negative TCF blocks them, and a known Wg target, decapentaplegic, is activated in double mutant clones, strongly suggesting that the phenotypes result from activated Wg signaling. We also explored the roles of classic cadherins in differential adhesion. Finally, we propose a model suggesting that Wg signaling regulates fine scale cell fates along the anterior-posterior axis, in part by creating an adhesion gradient and consider possible alternate explanations for our observations.

Drosophila APC2 and APC1 have overlapping roles in the larval brain despite their distinct intracellular localizations.

The tumor suppressor APC and its homologs, first identified for a role in colon cancer, negatively regulate Wnt signaling in both oncogenesis and normal development, and play Wnt-independent roles in cytoskeletal regulation. Both Drosophila and mammals have two APC family members. We further explored the functions of the Drosophila APCs using the larval brain as a model. We found that both proteins are expressed in the brain. APC2 has a highly dynamic, asymmetric localization through the larval neuroblast cell cycle relative to known mediators of embryonic neuroblast asymmetric divisions. Adherens junction proteins also are asymmetrically localized in neuroblasts. In addition they accumulate with APC2 and APC1 in nerves formed by axons of the progeny of each neuroblast-ganglion mother cell cluster. APC2 and APC1 localize to very different places when expressed in the larval brain: APC2 localizes to the cell cortex and APC1 to centrosomes and microtubules. Despite this, they play redundant roles in the brain; while each single mutant is normal, the zygotic double mutant has severely reduced numbers of larval neuroblasts. Our experiments suggest that this does not result from misregulation of Wg signaling, and thus may involve the cytoskeletal or adhesive roles of APC proteins.

Drosophila APC2 and APC1 play overlapping roles in wingless signaling in the embryo and imaginal discs.

The regulation of signal transduction plays a key role in cell fate choices, and its disregulation contributes to oncogenesis. This duality is exemplified by the tumor suppressor APC. Originally identified for its role in colon tumors, APC family members were subsequently shown to negatively regulate Wnt signaling in both development and disease. The analysis of the normal roles of APC proteins is complicated by the presence of two APC family members in flies and mice. Previous work demonstrated that, in some tissues, single mutations in each gene have no effect, raising the question of whether there is functional overlap between the two APCs or whether APC-independent mechanisms of Wnt regulation exist. We addressed this by eliminating the function of both Drosophila APC genes simultaneously. We find that APC1 and APC2 play overlapping roles in regulating Wingless signaling in the embryonic epidermis and the imaginal discs. Surprisingly, APC1 function in embryos occurs at levels of expression nearly too low to detect. Further, the overlapping functions exist despite striking differences in the intracellular localization of the two APC family members.