{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\nBPIFB1 is a secreted protein that plays an important role in lung homeostasis and immune regulation. Autoimmune targeting of lung‐specific BPIFB1 is linked to interstitial lung disease (ILD) in patients with autoimmune syndromes such as APS1, and autoantibodies against BPIFB1 have been detected not only in APS1‐ILD but also in subsets of patients with connective tissue disease–associated and idiopathic ILD. In parallel, immunolocalization studies in mice have revealed that BPIFB1 is expressed in select subsets of goblet cells in the nasal passages and pharynx as well as in specific serous glands, suggesting a tissue‐restricted role in the airway and upper respiratory tract."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "1"}]}, {"type": "t", "text": "\n"}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nBeyond its role in mature tissues, BPIFB1 (also referred to as LPLUNC1 in some studies) has been implicated in developmental processes. Transient and asymmetric expression of a related form in the embryonic mouse node suggests that lipid‐binding and transfer functions of BPIFB1 may contribute to left–right axis formation. Moreover, increased BPIFB1 transcript levels in parotid acinar cells from non‐obese diabetic mice—an animal model of Sjögren’s syndrome—highlight its potential involvement in exocrine gland pathology."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "3"}]}, {"type": "t", "text": "\n"}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nIn the airway, BPIFB1 is emerging as a key regulator of mucus composition and mucociliary clearance. Genetic mapping studies identified BPIFB1 as a candidate gene underlying natural variation in airway levels of the major mucin MUC5B. Subsequent investigations demonstrated that BPIFB1 modulates mucus biophysical and biochemical properties, with knockout studies in mice showing impaired mucociliary clearance in the absence of this protein. Although research in related fields (such as studies on CETP inhibitors in metabolic dysfunction) provides a contrasting perspective on protein modulators in systemic physiology, the collective genetic and in vivo functional data firmly establish BPIFB1 as an important component of airway defense."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "5", "end_ref": "7"}]}, {"type": "t", "text": "\n"}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "Anthony K Shum, Mohammad Alimohammadi, Catherine L Tan, et al. 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"}, {"type": "b", "children": [{"type": "t", "text": "Differential localisation of BPIFA1 (SPLUNC1) and BPIFB1 (LPLUNC1) in the nasal and oral cavities of mice."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Cell Tissue Res (2012)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1007/s00441-012-1490-9"}], "href": "https://doi.org/10.1007/s00441-012-1490-9"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "22986921"}], "href": "https://pubmed.ncbi.nlm.nih.gov/22986921"}]}, {"type": "r", "ref": 3, "children": [{"type": "t", "text": "Juan Hou, Kenta Yashiro, Yasushi Okazaki, et al. 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