Opportunistic coeliac disease screening in undifferentiated presentations to paediatric acute care.

AIM: Coeliac disease (CD) can remain undiagnosed due to absent/atypical symptoms. We evaluated screening for CD in undifferentiated paediatric patients in the emergency department (ED). METHODS: Subjects were all patients presenting to a children's hospital ED during the study period who had blood taken. Plasma remaining after routine care was tested for tissue transglutaminase IgA (tTG IgA) and deamidated gliadin IgG (DGP IgG) antibodies. Patients with positive results were counselled and offered confirmatory testing, then gastroenterology review if warranted. RESULTS: An initial positive result for either DGP IgG or tTG IgA was found in 4.2% (44/1055). There was a normalisation of 76% (19/25) of positive DGP IgG and 44% (4/9) of tTG IgA results on repeat testing, which was not available in 27% (12/44). The prevalence of biopsy-confirmed CD was 0.7% (7/1055), including two new diagnoses and five subjects with known CD. Three likely cases could not be confirmed. All confirmed and likely cases were >10 years old. In children >10 years old, the prevalence of either biopsy-confirmed or likely CD was 3.3% (10/302). A family history of CD, growth concerns, recurrent abdominal pain and lethargy were associated with persistence of positive tests. CONCLUSION: Opportunistic testing for CD in ED requires further investigation as a CD screening strategy. Our results suggest optimal screening in this setting should be by initially testing for tTG IgA and total IgA in children >10 years old (minimising transiently positive tests). Transiently positive coeliac antibodies may also warrant further investigation as a predictor of future CD.

Cytokine-mediated STAT-dependent pathways underpinning human B-cell differentiation and function.

B cells are fundamental to host defence against infectious diseases; indeed, the ability of humans to elicit robust antibody responses following exposure to foreign antigens underpins long-lived humoral immunity and serological memory, as well as the success of most currently administered vaccines. However, B cells also have a dark side - they can cause myriad diseases, including autoimmunity, atopy, allergy and malignancy. Thus, it is critical to understand the molecular requirements for generating effective, high-affinity, specific immune responses following natural infection or vaccination, as well as for constraining B-cell function to mitigate B-cell-mediated immune dyscrasias. In this review, we discuss recent developments that have been derived from the identification and detailed analysis of individuals with inborn errors of immunity that disrupt cytokine signalling, resulting in immune dysregulatory conditions. These studies have defined fundamental cytokine/cytokine receptor/signal transducer and activator of transcription (STAT) signalling pathways that are critical for the generation and maintenance of human memory B-cell and plasma cell subsets during host defence, as well as revealed mechanisms of disease pathogenesis causing immune deficiency, autoimmunity and atopy. More importantly, these studies have identified molecules that could be targeted to either enhance humoral immunity in the settings of infection or vaccination, or attenuate humoral immunity that contributes to antibody-mediated autoimmunity or allergy.

Osteoclasts recycle via osteomorphs during RANKL-stimulated bone resorption.

Osteoclasts are large multinucleated bone-resorbing cells formed by the fusion of monocyte/macrophage-derived precursors that are thought to undergo apoptosis once resorption is complete. Here, by intravital imaging, we reveal that RANKL-stimulated osteoclasts have an alternative cell fate in which they fission into daughter cells called osteomorphs. Inhibiting RANKL blocked this cellular recycling and resulted in osteomorph accumulation. Single-cell RNA sequencing showed that osteomorphs are transcriptionally distinct from osteoclasts and macrophages and express a number of non-canonical osteoclast genes that are associated with structural and functional bone phenotypes when deleted in mice. Furthermore, genetic variation in human orthologs of osteomorph genes causes monogenic skeletal disorders and associates with bone mineral density, a polygenetic skeletal trait. Thus, osteoclasts recycle via osteomorphs, a cell type involved in the regulation of bone resorption that may be targeted for the treatment of skeletal diseases.