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Hypersensitivity pneumonitis (HP) is an immune-mediated inflammatory interstitial lung disease that may evolve to pulmonary fibrosis, a progressive disorder with a poor prognosis characterized by fibroblast activation and extracellular matrix accumulation. In HP lung fibroblasts, the gene expression of proteins involved in the interaction with the immune response, their isoforms, and how they influence their phenotype have yet to be elucidated. We analyzed the expression and splicing variants of 16 target genes involved in the interaction between HP fibroblasts and immune signaling and evaluated possible correlations with clinical data. The comparison of HP and control fibroblasts revealed distinct gene expression patterns. HP lung fibroblasts displayed an increased expression of IFI27 and PDFGRA and a downregulation of IL17RC and TGFBR3. IFI27 immunoreactive protein was markedly increased in HP lung tissues and normal fibroblasts treated with TGF-β. Furthermore, IFI27 overexpression in normal fibroblasts increased α-SMA and decreased cell number over time. The isoform analysis showed similar expression patterns for most genes, except for the AGER receptor with increased soluble variants relative to full-length AGER in HP fibroblasts. These findings indicate important differences in the expression of genes related to the immune response by HP fibroblasts, highlighting their unique characteristics and providing further insight into a possible profibrotic role of IFI27 in the disease., (© 2024. The Author(s).)

Background: Hypersensitivity pneumonitis is an immune-mediated disease triggered by exposure to organic particles in susceptible individuals. It has been reported that a subgroup of patients with hypersensitivity pneumonitis develops autoantibodies with or without clinical manifestations of autoimmune disease. However, the mechanisms involved in this process and the effect of the autoantibodies on clinical course in hypersensitivity pneumonitis is unknown. We evaluated the association between human leukocyte antigen (HLA) class II alleles and hypersensitivity pneumonitis patients with and without autoantibodies., Methods: 170 hypersensitivity pneumonitis patients were included. We analysed the presence of antinuclear antibodies, rheumatoid factor, anti-SSA/Ro, anti-SSB/La and anti-CCP at the time of diagnosis. In addition, in a subset of patients we evaluated anti-Scl-70, anti-neutrophil cytoplasmic antibody, and anti-DNA. HLA typing was performed using PCR sequence-specific primers in a high-resolution modality, including HLA-DRB1 and HLA-DQB1 loci. Statistical analysis was performed employing Epi-Info v7 and SPSS v20., Results: 60 hypersensitivity pneumonitis patients showed sera autoantibodies (HPAbs + ), and 110 hypersensitivity pneumonitis patients did not (HPAbs - ). The frequency of the allele HLA-DRB1*03:01 was remarkably increased in the HPAbs + group (10.8% versus 0.45%; OR 30.14, 95% CI 3.83-237.1; p=1.65×10 -4 after Bonferroni's correction). Likewise, we found that the haplotype DRB1*03:01-DQB1*02:01 , which is part of the 8.1 ancestral haplotype, a major genetic determinant of autoimmune diseases, confers significant risk to develop autoantibodies (OR 19.23, 95% CI 2.37-155.9; p=0.0088 after Bonferroni's correction). In addition, the HLA-DRB1*03:01 allele was associated with higher mortality in patients with hypersensitivity pneumonitis (adjusted OR 5.9, 95% CI 1.05-33.05; p=0.043)., Conclusions: A subset of hypersensitivity pneumonitis patients presents circulating autoantibodies and higher mortality that are associated with some alleles of 8.1 ancestral haplotype., Competing Interests: Conflict of interest: I. Buendía-Roldán has nothing to disclose. Conflict of interest: L. Santiago-Ruiz has nothing to disclose. Conflict of interest: G. Pérez-Rubio has nothing to disclose. Conflict of interest: M. Mejía has nothing to disclose. Conflict of interest: J. Rojas-Serrano has nothing to disclose. Conflict of interest: E. Ambrocio-Ortiz has nothing to disclose. Conflict of interest: G. Benítez-Valdez has nothing to disclose. Conflict of interest: M. Selman has nothing to disclose. Conflict of interest: R. Falfán-Valencia has nothing to disclose., (Copyright ©ERS 2020.)

Fibrosing diseases are causes of morbidity and mortality around the world, and they are characterized by excessive extracellular matrix (ECM) accumulation. The bHLH transcription factor scleraxis (SCX) regulates the synthesis of ECM proteins in heart fibrosis. SCX expression was evaluated in lung fibroblasts and tissue derived from fibrotic disease patients and healthy controls. We also measured SCX in sera from 57 healthy controls, and 56 Idiopathic Pulmonary Fibrosis (IPF), 40 Hypersensitivity Pneumonitis (HP), and 100 Systemic Sclerosis (SSc) patients. We report high SCX expression in fibroblasts and tissue from IPF patients versus controls. High SCX-serum levels were observed in IPF (0.663 ± 0.559 ng/mL, p < 0.01) and SSc (0.611 ± 0.296 ng/mL, p < 0.001), versus controls (0.351 ± 0.207 ng/mL) and HP (0.323 ± 0.323 ng/mL). Serum levels of the SCX heterodimerization partner, TCF3, did not associate with fibrotic illness. IPF patients with severely affected respiratory capacities and late-stage SSc patients presenting anti-topoisomerase I antibodies and interstitial lung disease showed the highest SCX-serum levels. SCX gain-of-function induced the expression of alpha-smooth muscle actin (α-SMA/ACTA2) in fibroblasts when co-overexpressed with TCF3. As late and severe stages of the fibrotic processes correlated with high circulating SCX, we postulate it as a candidate biomarker of fibrosis and a potential therapeutic target.

Among hypersensitivity pneumonitis (HP) patients have been identified who develop autoantibodies with and without clinical manifestations of autoimmune disease. Genetic factors involved in this process and the effect of these autoantibodies on the clinical phenotype are unknown. Matrix metalloproteinases (MMPs) have an important role in architecture and pulmonary remodeling. The aim of our study was to identify polymorphisms in the MMP1 , MMP2 , MMP9 and MMP12 genes associated with susceptibility to HP with the presence of autoantibodies (HPAbs+). Using the dominant model of genetic association, comparisons were made between three groups. For rs7125062 in MMP1 (CC vs . CT+TT), we found an association when comparing groups of patients with healthy controls: HPAbs+ vs. HC ( p < 0.001, OR = 10.62, CI 95% = 4.34 - 25.96); HP vs. HC ( p < 0.001, OR = 7.85, 95% CI 95% = 4.54 - 13.57). This rs11646643 in MMP2 shows a difference in the HPAbs+ group by the dominant genetic model GG vs. GA+AA, ( p = 0.001, OR = 8.11, CI 95% = 1.83 - 35.84). In the linear regression analysis, rs11646643 was associated with a difference in basal forced vital capacity (FVC)/12 months ( p = 0.013, = 0.228, 95% CI95% = 1.97 - 16.72). We identified single-nucleotide polymorphisms (SNPs) associated with the risk of developing HP, and with the evolution towards the phenotype with the presence of autoantibodies. Also, to the decrease in plasma MMP-2 levels.

Hypersensitivity Pneumonitis (HP) is a lung inflammatory disorder caused by inhalation of organic particles by a susceptible host. Since only a small proportion of individuals exposed to HP-related antigens develop the disease, a genetic predisposition is largely suspected. However, studies regarding genetic susceptibility in this disease are scanty. We have previously found evidence supporting increased risk associated to the major histocompatibility complex (MHC) in sporadic HP. In the present study, we conducted a family-based research that includes nine multicase families with at least two related HP patients (RHP). We evaluated 19 RHP individuals, 25 additional healthy first-degree relatives (REA) and 246 healthy unrelated individuals (HUI). HLA class II typing (DRB1/3/4/5, DQA1, DQB1, DPA1, DPB1, DMA and DMB), and -863, -308 and -238 polymorphisms in the promoter region of TNF-α were performed by PCR based methods. We identified an increased frequency of HLA-DRB1*04:07, DRB1*04:05, DRB1*11:01 and DRB1*13:01 alleles in RHP individuals compared to healthy controls (p < 0.05). A significant higher frequency of DRB1*04:07-DQB1*03:02, DRB1*04:05-DQB1*03:02, and DRB1*04:03-DQB1*03:02 haplotypes was also detected in the group of patients. Likewise, TNF-238 GG genotype was more frequent in the RHP group as compared to REA (p = 0.01, OR = 7.2). Finally, the combination of HLA-DRB1*04 alleles and TNF-238 GG was significantly increased in the RHP group (p = 0.01, OR = 6.93). These findings indicate that genes located within the MHC region confer susceptibility to familial HP in Mexicans., (Copyright © 2013. Published by Elsevier Ltd.)

Hypersensitivity pneumonitis (HP) is an inflammatory interstitial lung disease caused by a wide variety of organic particles and certain small-molecular weight chemical compounds that provoke an exaggerated immune response in susceptible individuals. The clinical manifestations are heterogeneous and have been classically described as acute, subacute and chronic. The chronic form has an insidious onset over a period of months or years, with progressive dyspnea and often evolves to fibrosis. The pathology is characterized by a bronchiolocentric interstitial mononuclear cell infiltration, nonnecrotizing poorly formed granulomas, cellular pneumonitis and variable degrees of fibrosis. However, morphological diagnosis of HP is complicated because the subacute/chronic forms may be difficult to distinguish from idiopathic pulmonary fibrosis/usual interstitial pneumonia and nonspecific interstitial pneumonia. In general, diagnosis of HP represents a challenge for clinicians that need to weigh a constellation of clinical, laboratory, radiographic and (when available) pathological evidence for each patient to assess the certainty of the diagnosis. The cornerstone of therapy is antigen avoidance. Although clinical trials are scanty, corticosteroids are usually indicated based upon expert opinion. In this review we summarize the current evidence regarding the diagnostic criteria and therapeutic strategies as well as the immunopathological mechanisms putatively implicated in the development of the disease., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Background: Idiopathic pulmonary fibrosis (IPF), a devastating lung disorder of unknown aetiology, and chronic hypersensitivity pneumonitis (HP), a disease provoked by an immunopathologic reaction to inhaled antigens, are two common interstitial lung diseases with uncertain pathogenic mechanisms. Previously, we have shown in other upper and lower airway diseases that immunoglobulin free light chains (FLCs) are increased and may be involved in initiating a local inflammation. In this study we explored if such a mechanism may also apply to HP and IPF., Methods: In this study we examined the presence of FLC in serum and BAL fluid from 21 IPF and 22 HP patients and controls. IgG, IgE and tryptase concentrations were measured in BAL fluid only. The presence of FLCs, plasma cells, B cells and mast cells in lung tissue of 3 HP and 3 IPF patients and 1 control was analyzed using immunohistochemistry., Results: FLC concentrations in serum and BAL fluid were increased in IPF and HP patients as compared to control subjects. IgG concentrations were only increased in HP patients, whereas IgE concentrations were comparable to controls in both patient groups. FLC-positive cells, B cells, plasma cells, and large numbers of activated mast cells were all detected in the lungs of HP and IPF patients, not in control lung., Conclusion: These results show that FLC concentrations are increased in serum and BAL fluid of IPF and HP patients and that FLCs are present within affected lung tissue. This suggests that FLCs may be involved in mediating pathology in both diseases.