The Nkrp1 (Klrb) family of NK cell receptors and their genetically linked Clr (Clec2) ligands are conserved between rodents and humans. Nonetheless, certain mouse and rat Nkrp1 genes exhibit significant allelic polymorphism between inbred strains. We previously demonstrated that the Nkrp1-Clr recognition system is genetically and functionally conserved between the B6 and BALB/c strains, with focused sequence divergence evident in certain genes (e.g., Nkrp1b,c). Here, we extend this finding by mapping the 129-strain Nkrp1-Clr gene cluster, which is structurally conserved yet displays significant sequence divergence relative to the B6 haplotype. In addition, we show that 129-strain NK cells possess comparable Nkrp1 and Clr transcript expression, and characterize several NKR-P1:Clr interactions that are functionally conserved between the B6 and 129 strains, including documented and novel receptor-ligand pairs. Thus, despite significant allelic polymorphism observed in the Nkrp1-Clr region, the overall genetic organization and functional repertoire appear to be conserved among mouse strains, in contrast to the striking variation observed in the corresponding Ly49 region. These data extend our knowledge of the complex genetically linked Nkrp1-Clr NK recognition system in mice.

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Objective: To provide a systematic review of the existing pediatric decannulation protocols, including the role of polysomnography, and their clinical outcomes.Methods: Five online databases were searched from database inception to May 29, 2020. Study inclusion was limited to publications that evaluated tracheostomy decannulation in children 18 years of age and younger. Data extracted included patient demographics and primary indication for tracheostomy. Methods used to assess readiness for decannulation were noted including the use of bronchoscopy, tracheostomy tube modifications, and gas exchange measurements. After decannulation, details regarding mode of ventilation, location, and length of observation period, and clinical outcomes were also collected. Descriptive statistical analyses were performed.Results: A total of 24 studies including 1395 children were reviewed.Tracheostomy indications included upper airway obstruction at a well-defined anatomic site (35%), upper airway obstruction not at a well-defined site (12%) and need for long-term ventilation and pulmonary care (53%). Bronchoscopy was routinely used in 23 of 24 (96%) protocols. Tracheostomy tube modifications in the protocols included capping (n = 20, 83%), downsizing (n = 14, 58%), and fenestrations (n = 2, 8%). Measurements of gas exchange included polysomnography (n = 13/18, 72%), oximetry (n = 10/18, 56%), blood gases (n = 3,17%), and capnography (n = 3, 17%). After decannulation, children in 92% of protocols were transitioned to room air. Observation period of 48 h or less was used in 76% of children.Conclusions: There exists large variability in pediatric decannulation protocols.Polysomnography plays an integral role in assessing most children for tracheostomy removal. Evidence-based guidelines to standardize pediatric tracheostomy care remain an urgent priority.