Levels of Lysozyme and SLPI in Bronchoalveolar Lavage: Exploring Their Role in Interstitial Lung Disease.

Interstitial lung diseases (ILDs) are characterized by inflammation or fibrosis of the pulmonary parenchyma. Despite the involvement of immune cells and soluble mediators in pulmonary fibrosis, the influence of antimicrobial peptides (AMPs) remains underexplored. These effector molecules display a range of activities, which include immunomodulation and wound repair. Here, we investigate the role of AMPs in the development of fibrosis in ILD. We compare the concentration of different AMPs and different cytokines in 46 fibrotic (F-ILD) and 17 non-fibrotic (NF-ILD) patients by ELISA and using peripheral blood mononuclear cells from in vitro stimulation in the presence of lysozyme or secretory leukocyte protease inhibitor (SLPI) from 10 healthy donors. We observed that bronchoalveolar lavage (BAL) levels of AMPs were decreased in F-ILD patients (lysozyme: p < 0.001; SLPI: p < 0.001; LL-37: p < 0.001; lactoferrin: p = 0.47) and were negatively correlated with levels of TGF-ß (lysozyme: p = 0.02; SLPI: p < 0.001) and IL-17 (lysozyme: p < 0.001; SLPI: p < 0.001). We observed that lysozyme increased the percentage of CD86+ macrophages (p < 0.001) and the production of TNF-α (p < 0.001). We showed that lysozyme and SLPI were associated with clinical parameters (lysozyme: p < 0.001; SLPI: p < 0.001) and disease progression (lysozyme: p < 0.001; SLPI: p = 0.01). These results suggest that AMPs may play an important role in the anti-fibrotic response, regulating the effect of pro-fibrotic cytokines. In addition, levels of lysozyme in BAL may be a potential biomarker to predict the progression in F-ILD patients.

The immunoregulatory role of IL-35 in patients with interstitial lung disease.

Pulmonary fibrosis involves various types of immune cells and soluble mediators, including TGF-ß and IL-35, a recently identified heterodimeric cytokine that belongs to the IL-12 cytokine family. However, the effect of regulatory IL-35 may play an important role in fibrotic diseases. The aim of this paper is to explore the immunoregulatory role of IL-35 in the development of fibrosis in interstitial lung disease (ILD). To gain a better understanding of this issue, the concentrations of IL-35 and different profibrotic cytokines in fibrotic (F-ILD) and non-fibrotic (NF-ILD) patients by ELISA were compared to that of intracellular IL-35 and IL-17 on CD4+ T cells stimulated in the presence of BAL or with different ratios of recombinant IL-35 (rIL-35) and TGF-ß (rTGF-ß), which were evaluated by flow cytometry. We observed that BAL concentration of IL-35 was lower in F patients (p < 0.001) and was negatively correlated with concentrations of TGF-ß (p < 0.001) and IL-17 (p < 0.001). In supplemented cell cultures, BAL from NF but not F patients enhanced the percentage of IL-35 + CD4+ T (p < 0.001) cells and decreased the percentage of IL-17 + CD4+ T cells (p < 0.001). The percentage of IL-35 + CD4+ T cells correlated positively with BAL concentration of IL-35 (p = 0.02), but correlated negatively with BAL concentrations of IL-17 (p = 0.007) and TGF-ß (p = 0.01). After adjusting the concentrations of recombinant cytokines to establish a TGF-ß: IL-35 ratio of 1:4, an enhanced percentage of IL-35 + CD4+ T cells (p < 0.001) but a decreased percentage of IL-17 + CD4+ T cells (p < 0.001) was observed. After adding recombinant IL-35 to the BAL from F patients until a 1:4 ratio of TGF-ß: IL-35 was reached, a significantly increased percentage of IL-35 + CD4+ T cells (p < 0.001) and a decreased percentage of IL-17 + CD4+ T cells (p = 0.003) was found. These results suggest that IL-35 may induce an anti-fibrotic response, regulating the effect of TGF-ß and the inflammatory response on CD4+ T cells. In addition, the TGF-ß: IL-35 ratio in BAL has been shown to be a potential biomarker to predict the outcome of F patients with ILD.

Prognostic factors of progressive fibrotic hypersensitivity pneumonitis: a large, retrospective, multicentre, observational cohort study.

Background: Fibrotic hypersensitivity pneumonitis (fHP) is an immune-mediated interstitial lung disease caused by sensitisation to chronic allergen inhalation. This study aimed to determine prognostic indicators of progression and mortality in fHP. Methods: This was a retrospective, multicentre, observational, cross-sectional cohort study of consecutive patients diagnosed with fHP from 1 January 2012 to 31 December 2021. Multivariate Cox regression analyses were used to calculate hazard ratios (HRs) with 95% confidence intervals for predictors of progression and survival. Results: A total of 403 patients were diagnosed with fHP: median (interquartile range) age 66.5 (14.0) years, 51.9% females and 55.1% never-smokers. The cause of fHP was mainly fungal (39.7%) or avian (41.4%). Lung biopsy was performed in 269 cases (66.7%). In the whole cohort the variables that were related to mortality or lung transplant were older age (HR 1.08; p<0.001), percentage predicted forced vital capacity (HR 0.96; p=0.001), lymphocytosis in bronchoalveolar lavage (BAL) (HR 0.93; p=0.001), presence of acute exacerbation during follow-up (HR 3.04; p=0.001) and GAP (gender, age and lung physiology) index (HR 1.96; p<0.01). In the group of biopsied patients, the presence of fibroblastic foci at biopsy (HR 8.39; p<0.001) stands out in multivariate Cox regression analyses as a highly significant predictor for increased mortality or lung transplant. GAP index (HR 1.26; p=0.009), lymphocytosis in BAL (HR 0.97; p=0.018) and age (HR 1.03; p=0.018) are also predictors of progression. Conclusions: The study identified several prognostic factors for progression and/or survival in fHP. The presence of fibroblastic foci at biopsy was a consistent predictor for increased mortality and the presence of lymphocytosis in BAL was inversely related to mortality.