Interstitial lung disease (ILD) encompasses a diverse group of disorders characterized by chronic inflammation and fibrosis of the pulmonary interstitium. Three ILDs, namely idiopathic pulmonary fibrosis (IPF), fibrotic hypersensitivity pneumonitis (fHP), and connective tissue disease-associated ILD (CTD-ILD), exhibit similar progressive fibrosis phenotypes, yet possess distinct etiologies, encouraging us to explore their different underlying mechanisms.
Transcriptome data of fibrotic lung tissues from patients with IPF, fHP, and CTD-ILD were subjected to functional annotation, network, and pathway analyses. Additionally, we employed the xCell deconvolution algorithm to predict immune cell infiltration in patients with fibrotic ILDs and healthy controls.
We identified a shared progressive fibrosis-related module in these diseases which was related to extracellular matrix (ECM) degradation and production and potentially regulated by the p53 family transcription factors. In IPF, neuron-related processes emerged as a critical specific mechanism in functional enrichment. In fHP, we observed that B cell signaling and immunoglobulin A (IgA) production may act as predominant processes, which was further verified by B cell infiltration and the central role of CD19 gene. In CTD-ILD, active chemokine processes were enriched, and active dendritic cells (aDCs) were predicted to infiltrate the lung tissues.
This study revealed shared and specific molecular and cellular pathways among IPF, fHP, and CTD-ILD, providing a basis for understanding their pathogenesis and identifying potential therapeutic targets.

BACKGROUND: Hypersensitivity pneumonitis (HP) is a common type among all the interstitial lung diseases, and transbronchial lung cryobiopsy is an alternative diagnostic technique for interstitial lung diseases. In this study, we describe the clinical and pathological features of fibrotic hypersensitivity pneumonitis diagnosed with transbronchial lung cryobiopsy (TBLC).
METHODS: A total of 46 diffused parenchyma lung disease (DPLD) patients received TBLC were included in this study. Medical records including medical history spirometry examinations, 6-min walk test (6MWT) results, high resolution computed tomographic (HRCT) scans, BAL, and histopathology were collected. Results of HRCT and histopathology were compared and classified, especially.
RESULTS: Sixteen patients were diagnosed with fibrotic HP, the mean age of whom was 56.3 ± 12.1 years, and 62.5% of them were male. Three of the 16 patients had been misdiagnosed as tuberculosis and received antituberculosis medications, five patients had been diagnosed as unclassifiable pulmonary fibrosis, and five patients had been diagnosed as idiopathic pulmonary fibrosis (IPF). Thirteen (81.3%) patients had a normal lymphocyte count in BAL. The pathological features of usual interstitial pneumonia (UIP) were detected in 11 (68.8%) of the cases, poor defined granulomatous was detected in nine (56.3%) of the cases, and bronchiolocentric fibrosis was detected in two (12.5%) of the 16 cases.
CONCLUSIONS: Fibrotic hypersensitivity pneumonitis should be included in differential diagnosis of pulmonary fibrosis. Pathological characteristics of fibrotic hypersensitivity pneumonitis could be demonstrated from cryobiopsy lung tissue. TBLC is recommended as an alternative diagnostic technique, which may improve the specificity of hypersensitivity pneumonia detection, and UIP is the most frequent pathological finding.

BACKGROUND: Fibrotic hypersensitivity pneumonitis (FHP) is an allergic and diffuse pneumonia caused by repeated inhalation of antigenic substances, and sometimes developed in people working in specific environments. While novel antigens and exposures continued to be described, physicians should maintain a high suspicion of potential exposures. A detailed assessment of the patient\'s occupational exposures as well as living environment is necessary and complete allergen avoidance is the first and most important step in the management of FHP once the allergens are determined.
METHODS: A 35-year-old female was admitted to the hospital with a cough and breathing difficulties for more than one year. She was a nonsmoker and a manufacturer of halogen dishes, which are characteristic Chinese foods, for 15 years without any protection. High resolution computed tomography of the chest demonstrated an interstitial pneumonia pattern. Pulmonary function examination showed restricted ventilation dysfunction and a significant reduction in dispersion ability. Cell differentiation in bronchoalveolar lavage fluid demonstrated lymphocytosis (70.4%) with an increased lymphocyte CD4/CD8 ratio (0.94). Transbronchial lung biopsy combined with lung puncture pathology showed diffuse uniform alveolar interval thickening, chronic inflammatory cell infiltration, a proliferation of tissue in the bronchial wall fiber and alveolar epithelial follicle degeneration, resulting in fibrosis.
CONCLUSIONS: Exposure to spices used for the production of halogen dishes may cause FHP.