Activation of the AIM2 Receptor in Circulating Cells of Post-COVID-19 Patients With Signs of Lung Fibrosis Is Associated With the Release of IL-1α, IFN-α and TGF-ß.

Severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2), responsible for COVID-19, has caused a global pandemic. Observational studies revealed a condition, herein called as Long-COVID syndrome (PC), that affects both moderately and severely infected patients, reducing quality-of-life. The mechanism/s underlying the onset of fibrotic-like changes in PC are still not well defined. The goal of this study was to understand the involvement of the Absent in melanoma-2 (AIM2) inflammasome in PC-associated lung fibrosis-like changes revealed by chest CT scans. Peripheral blood mononuclear cells (PBMCs) obtained from PC patients who did not develop signs of lung fibrosis were not responsive to AIM2 activation by Poly dA:dT. In sharp contrast, PBMCs from PC patients with signs of lung fibrosis were highly responsive to AIM2 activation, which induced the release of IL-1α, IFN-α and TGF-ß. The recognition of Poly dA:dT was not due to the activation of cyclic GMP-AMP (cGAMP) synthase, a stimulator of interferon response (cGAS-STING) pathways, implying a role for AIM2 in PC conditions. The release of IFN-α was caspase-1- and caspase-4-dependent when AIM2 was triggered. Instead, the release of pro-inflammatory IL-1α and pro-fibrogenic TGF-ß were inflammasome independent because the inhibition of caspase-1 and caspase-4 did not alter the levels of the two cytokines. Moreover, the responsiveness of AIM2 correlated with higher expression of the receptor in circulating CD14+ cells in PBMCs from patients with signs of lung fibrosis.

Diabetic Pneumopathy-A New Diabetes-Associated Complication: Mechanisms, Consequences and Treatment Considerations.

Patients with diabetes are over-represented among the total cases reported with "idiopathic" pulmonary fibrosis (IPF). This raises the question, whether this is an association only or whether diabetes itself can cause pulmonary fibrosis. Recent studies in mouse models of type 1 and type 2 diabetes demonstrated that diabetes causes pulmonary fibrosis. Both types of diabetes trigger a cascade, starting with increased DNA damage, an impaired DNA repair, and leading to persistent DNA damage signaling. This response, in turn, induces senescence, a senescence-associated-secretory phenotype (SASP), marked by the release of pro-inflammatory cytokines and growth factors, finally resulting in fibrosis. Restoring DNA repair drives fibrosis into remission, thus proving causality. These data can be translated clinically to patients with type 2 diabetes, characterized by long-term diabetes and albuminuria. Hence there are several arguments, to substitute the term "idiopathic" pulmonary fibrosis (IPF) in patients with diabetes (and exclusion of other causes of lung diseases) by the term "diabetes-induced pulmonary fibrosis" (DiPF). However, future studies are required to establish this term and to study whether patients with diabetes respond to the established therapies similar to non-diabetic patients.

Predicting mortality in non-cystic fibrosis bronchiectasis patients using distance-saturation product.

BACKGROUND: The bronchiectasis severity index (BSI) and FACED score are currently used in predicting outcomes of non-cystic fibrosis bronchiectasis (NCFB). Distance-saturation product (DSP), the product of distance walked, and lowest oxygen saturation during the 6-min walk test showed strong predictive power of mortality in non-CF bronchiectasis patients. This study aimed to compare the efficacy of these scores and DSP in predicting mortality. METHODS AND PATIENTS: Our retrospective study included NCFB patients from January 2004 to December 2017. We recorded the basic data, pulmonary function, radiologic studies, sputum culture results, acute exacerbations (AE), emergency department (ED) visits, hospitalization, and mortality. RESULTS: A total 130 NCFB patients were analysed. The mean BSI score, FACED score, and DSP were 8.8 ± 4.9, 3.4 ± 1.7, and 413.1 ± 101.5 m%, respectively. BSI and FACED scores had comparable predictive power for AE (p=.011; p=.010, respectively). The BSI score demonstrated a significant correlation with ED visits (p=.0003). There were 12 deaths. Patients were stratified using a DSP cut-off value of 345 m% according to the best area under receiver operator characteristic curve (AUC) value in mortality. DSP was not correlated with AE and ED visits. BSI, FACED scores, and DSP demonstrated statistically significant correlations with hospitalization (p<.0001; p<.0001; p=.0007, respectively). The AUC for overall mortality was similar for BSI, FACED score, and DSP (0.80 versus 0.85, p=.491; 0.85 versus 0.83, p=.831). CONCLUSION: DSP had comparable predictive power for mortality as the well-validated BSI and FACED scores and is relatively easy to use in clinical practice.KEY MESSAGEDistance-saturation product (DSP) comprised with the product of distance walked, and lowest oxygen saturation during the 6-min walk test, which is common used in clinical practice.DSP demonstrated strong and comparable predictive power of mortality as the well-validated BSI and FACED scores in non-CF bronchiectasis patients.

sFlt-1 and CA 15.3 are indicators of endothelial damage and pulmonary fibrosis in SARS-CoV-2 infection.

COVID-19 pandemic led to a worldwide increase of hospitalizations for interstitial pneumonia with thrombosis complications, endothelial injury and multiorgan disease. Common CT findings include lung bilateral infiltrates, bilateral ground-glass opacities and/or consolidation whilst no current laboratory parameter consents rapidly evaluation of COVID-19 risk and disease severity. In the present work we investigated the association of sFLT-1 and CA 15.3 with endothelial damage and pulmonary fibrosis. Serum sFlt-1 has been associated with endothelial injury and sepsis severity, CA 15.3 seems an alternative marker for KL-6 for fibrotic lung diseases and pulmonary interstitial damage. We analysed 262 SARS-CoV-2 patients with differing levels of clinical severity; we found an association of serum sFlt-1 (ROC AUC 0.902, decision threshold > 90.3 pg/mL, p < 0.001 Sens. 83.9% and Spec. 86.7%) with presence, extent and severity of the disease. Moreover, CA 15.3 appeared significantly increased in COVID-19 severe lung fibrosis (ICU vs NON-ICU patients 42.6 ± 3.3 vs 25.7 ± 1.5 U/mL, p < 0.0001) and was associated with lung damage severity grade (ROC AUC 0.958, decision threshold > 24.8 U/mL, p < 0.0001, Sens. 88.4% and Spec. 91.8%). In conclusion, serum levels of sFlt-1 and CA 15.3 appeared useful tools for categorizing COVID-19 clinical stage and may represent a valid aid for clinicians to better personalise treatment.

Commonalities Between ARDS, Pulmonary Fibrosis and COVID-19: The Potential of Autotaxin as a Therapeutic Target.

Severe COVID-19 is characterized by acute respiratory distress syndrome (ARDS)-like hyperinflammation and endothelial dysfunction, that can lead to respiratory and multi organ failure and death. Interstitial lung diseases (ILD) and pulmonary fibrosis confer an increased risk for severe disease, while a subset of COVID-19-related ARDS surviving patients will develop a fibroproliferative response that can persist post hospitalization. Autotaxin (ATX) is a secreted lysophospholipase D, largely responsible for the extracellular production of lysophosphatidic acid (LPA), a pleiotropic signaling lysophospholipid with multiple effects in pulmonary and immune cells. In this review, we discuss the similarities of COVID-19, ARDS and ILDs, and suggest ATX as a possible pathologic link and a potential common therapeutic target.

Similarities and differences between IL11 and IL11RA1 knockout mice for lung fibro-inflammation, fertility and craniosynostosis.

Loss of function (LOF) in IL11RA infers IL11 signaling as important for fertility, fibrosis, inflammation and incompletely penetrant craniosynostosis. The impact of LOF in IL11 has not been characterized. We generated IL11 knockout (Il11-/-) mice that are born in expected ratios and have normal hematological profiles. Lung fibroblasts from Il11-/- mice are resistant to pro-fibrotic stimulation with TGFß1. Following bleomycin-induced lung injury, Il11-/- mice are protected from pulmonary fibrosis and exhibit lesser ERK, STAT3 and NF-kB activation, reduced Il1b, Timp1, Ccl2 and diminished IL6 expression, both at baseline and after injury: placing Il11 activity upstream of IL6 in this model. Il11-/- female mice are infertile. Unlike Il11ra1-/- mice, Il11-/- mice do not have craniosynostosis, have normal long bone mass and reduced body weights. These data further establish the role of IL11 signaling in lung fibrosis while suggesting that bone development abnormalities can be associated with mutation of IL11RA but not IL11, which may have implications for therapeutic targeting of IL11 signaling.

Increased Frequency of Activated Switched Memory B Cells and Its Association With the Presence of Pulmonary Fibrosis in Diffuse Cutaneous Systemic Sclerosis Patients.

Disease-associated, high-affinity pathological autoantibody production is a well-described consequence of immune dysregulation affecting B cells in systemic sclerosis (SSc), including the distribution of B-cell subsets. We have previously shown that the increased relative frequency of CD19+CD27+IgD- switched memory B cells is associated with the severe form of SSc. This study sought to analyze memory B cell subsets using an extended range of markers for further subdivision based on CD19, IgD, CD27, CD38 and CD95 phenotype, to define relationship between the alterations of memory B cell subsets and the clinical features of SSc. Peripheral blood samples were obtained from 21 SSc patients, including 14 diffuse (dcSSc) and 7 limited (lcSSc) cutaneous SSc patients, with disease duration of 2.7 ( ± 1.6) years. After purification of CD19+ B cells, multiparametric flow cytometry was performed and the frequencies of CD19+IgD-CD27-CD38+ double negative (DN) 1, CD19+IgDloCD27+CD38+ unswitched, CD19+IgD-CD27+CD38+CD95- resting switched and CD19+IgD-CD27+CD38-CD95+ activated switched memory (ASM) B cells were determined, and correlated with clinical features of SSc. The dcSSc patients had a higher frequency of ASM B cells (p = 0.028) compared to lcSSc patients. The percentage of ASM B cells was elevated in anti-Scl-70 (anti-topoisomerase I) antibody positive patients compared to negative patients (p = 0.016). Additionally, the frequency of ASM B cells was also increased in patients with pulmonary fibrosis (p = 0.003) suggesting that patients with severe form of SSc have higher ASM B cell ratios. Furthermore, the ratio of DN1 B cells was decreased (p = 0.029), while the level of anti-citrate synthase IgG natural autoantibody was elevated (p = 0.028) in patients with active disease. Our observations on the increase of ASM B cells in dcSSc and in patients with pulmonary fibrosis may point to the association of this alteration with the severe form of the disease. Functionally the correlation of ASM B cells as effector memory-plasma cell precursors with anti-topoisomerase I antibody positivity could reflect their contribution to pathological autoantibody production, whereas the decrease of memory precursor DN B cells and the increase of anti-citrate synthase IgG autoantibody may have potential significance in the assessment of disease activity.

Type 1 inflammatory endotype relates to low compliance, lung fibrosis, and severe complications in COVID-19.

BACKGROUND: Coronavirus disease 2019 (COVID-19) is an acute respiratory disease; approximately 5% of patients developing severe COVID-19. It is known that cytokine release is associated with disease severity, but the relationship between the different clinical phenotypes and inflammatory endotypes is not well understood. OBJECTIVE: This study investigated the association between inflammatory biomarker-based endotypes and severe COVID-19 phenotypes. METHODS: Interleukin (IL) -6, C-reactive protein (CRP), C-X-C motif chemokine (CXCL) 9, IL-18, C-C motif chemokine (CCL) 3, CCL17, IL-10, and vascular endothelial growth factor (VEGF) were measured in 57 COVID-19 patients, and their association with clinical characteristics was examined using a cluster analysis. RESULTS: Significantly higher blood levels of the eight inflammatory markers were noted in patients who developed acute respiratory distress syndrome (ARDS) than in those who did not develop ARDS (non-ARDS). Using a cluster analysis, the patient groups were classified into four clusters, of which two had patients with high IL-6 and CRP levels. In the cluster with high levels of Type 1 (T1) inflammatory markers such as CXCL9 and IL-18, 85% of the patients had ARDS, 65% of the patients developed acute kidney injury (AKI), and 78% of the patients developed pulmonary fibrosis. CONCLUSIONS: In the cluster with high levels of T1 inflammatory markers, the patients frequently suffered from tissue damage, manifested as ARDS and AKI. Our findings identified distinct T1 inflammatory endotypes of COVID-19 and suggest the importance of controlling inflammation by monitoring T1 biomarkers and treating accordingly to limit the severity of the disease.

Serum levels of inflammatory mediators as prognostic biomarker in silica exposed workers.

Silicosis is a diffuse interstitial lung disease caused by sustained inhalation of silica and silicates. Several cytokines are activated by their inhalation and can mediate the process of pulmonary fibrosis. The identification of biomarkers could allow an early diagnosis before the development of radiological alterations and help monitor the evolution of patients. The objetive of this study was to determine the clinical significance of specific biomarkers, to estimate their association with the development, severity and/or progression of silicosis, and identify determinants of this evolution. We conducted a prospective observational study in patients attending the pulmonology clinic from 2009 to 2018. Serum levels of the following inflammatory mediators were assessed: interleukin-6 (IL-6), interleukin 2 receptor subunit alpha (IL2R) interleukin 1 beta (IL1B), interleukin-8 (IL-8), tumour necrosis factor-alpha (TNF-α), transforming growth factor-beta1 (TGF-ß1), alpha-1 antitrypsin (AAT), C-reactive protein (CRP), lactate dehydrogenase (LDH) and ferritin in subjects exposed to silica, with and without silicosis. Association between those inflammatory mediators with lung function measurements and radiological severity of disease and their impact on prognosis were analysed. 337 exposed to silica (278 with silicosis) and 30 subjects in the control group were included. IL-8, α1AT, ferritin, CRP and LDH levels were higher in silicosis than in those exposed to silica without silicosis. IL-8, LDH and AAT levels were associated with progression of silicosis and IL-6, IL-8, LDH, AAT, ferritin, and CRP with vital status. The results of the ROC analysis indicated the potential of IL-8 as a biomarker in the presence of silicosis and for the prediction of mortality.

Recent Findings on Cell-Based Therapies for COVID19-Related Pulmonary Fibrosis.

COVID-19 has spread worldwide, including the United States, United Kingdom, and Italy, along with its site of origin in China, since 2020. The virus was first found in the Wuhan seafood market at the end of 2019, with a controversial source. The clinical symptoms of COVID-19 include fever, cough, and respiratory tract inflammation, with some severe patients developing an acute and chronic lung injury, such as acute respiratory distress syndrome (ARDS) and pulmonary fibrosis (PF). It has already claimed approximately 300 thousand human lives and the number is still on the rise; the only way to prevent the infection is to be safe till vaccines and reliable treatments develop. In previous studies, the use of mesenchymal stem cells (MSCs) in clinical trials had been proven to be effective in immune modulation and tissue repair promotion; however, their efficacy in treating COVID-19 remains underestimated. Here, we report the findings from past experiences of SARS and MSCs, and how SARS could also induce PF. Such studies may help to understand the rationale for the recent cell-based therapies for COVID-19.

Correlation of Krebs von den Lungen-6 and fibronectin with pulmonary fibrosis in coronavirus disease 2019.

OBJECTIVE: Coronavirus Disease 2019 (COVID-19) caused by a novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is still spreading worldwide, which may progress to pulmonary fibrosis (PF), leading to the worsen outcome. As the markers of lung injury, the correlation of Krebs von den Lungen-6 (KL-6) and fibronectin (Fn) with pulmonary fibrosis in COVID-19 was still unclear. METHODS: 113 patients diagnosed as COVID-19 were enrolled in this retrospective study, and divided into three categories as mild, moderate and severe cases. The concentrations of serum KL-6 and Fn at hospital admission were tested using the method of latex agglutination assay and immunoturbidimetic assay, respectively. RESULTS: Compared with that in the non-severe COVID-19 cases and normal control subjects, serum KL-6 concentration on admission was significantly higher in the severe group, which was positively correlated with C-reactive protein, and negatively correlated with lymphocytes count. Whereas, no obvious elevation in serum Fn concentration was investigated in COVID-19 patients with the different phenotypes. The severe cases displayed the higher incident rate of pulmonary fibrosis at hospital discharge. Compared with non-PF patients, the COVID-19 cases with PF had the higher serum KL-6 values. CONCLUSION: Serum KL-6 concentration was significantly elevated in severe COVID-19 patients, which may be useful for evaluating the disease severity. For early prevention of the development of pulmonary fibrosis, high concentrations of serum KL-6 in the early stage of COVID-19 should be paid close attention.

Obesity-induced Vitamin D Deficiency Contributes to Lung Fibrosis and Airway Hyperresponsiveness.

Vitamin D (VitD) has pleiotropic effects. VitD deficiency is closely involved with obesity and may contribute to the development of lung fibrosis and aggravation of airway hyperresponsiveness (AHR). We evaluated the causal relationship between VitD deficiency and the lung pathologies associated with obesity. In vivo effects of VitD supplementation were analyzed using high-fat diet (HFD)-induced obese mice and TGF-ß1 (transforming growth factor-ß1) triple transgenic mice. Effects of VitD supplementation were also evaluated in both BEAS-2B and primary lung cells from the transgenic mice. Obese mice had decreased 25-OH VitD and VitD receptor expressions with increases of insulin resistance, renin and angiotensin-2 system (RAS) activity, and leptin. In addition, lung pathologies such as a modest increase in macrophages, enhanced TGF-ß1, IL-1ß, and IL-6 expression, lung fibrosis, and AHR were found. VitD supplementation to HFD-induced obese mice recovered these findings. TGF-ß1-overexpressing transgenic mice enhanced macrophages in BAL fluid, lung expression of RAS, epithelial-mesenchymal transition markers, AHR, and lung fibrosis. VitD supplementation also attenuated these findings in addition to the attenuation of the expressions of TGF-ß1, and phosphorylated Smad-2/3 in lung. Supplementing in vitro-stimulated BEAS-2B and primary lung cells with VitD inhibited TGF-ß1 expression, supporting the suppressive effect of VitD for TGF-ß1 expression. These results suggest that obesity leads to VitD deficiency and worsens insulin resistance while enhancing the expression of leptin, RAS, TGF-ß1, and proinflammatory cytokines. These changes may contribute to the development of lung fibrosis and AHR. VitD supplementation rescues these changes and may have therapeutic potential for asthma with obesity.

Elevated Circulatory Levels of Microparticles Are Associated to Lung Fibrosis and Vasculopathy During Systemic Sclerosis.

Background: Microparticles (MPs) are vesicular structures that derive from multiple cellular sources. MPs play important roles in intercellular communication, regulation of cell signaling or initiation of enzymatic processes. While MPs were characterized in Systemic Sclerosis (SSc) patients, their contribution to SSc pathogenesis remains unknown. Our aim was to investigate the potential role of MPs in SSc pathophysiology and their impact on tissue fibrosis. Methods: Ninety-six SSc patients and 37 sex-matched healthy donors (HD) were enrolled in this study in order to quantify and phenotype their plasmatic MPs by flow cytometry. The ability of MPs purified from SSc patients and HD controls to modulate fibroblast's extra-cellular matrix genes expression was evaluated in vitro by reverse transcriptase quantitative polymerase chain reaction. Results: SSc patients exhibited a higher concentration of circulatory MPs compared to HD. This difference was exacerbated when we only considered patients that were not treated with methotrexate or targeted disease-modifying antirheumatic drugs. Total circulatory MPs were associated to interstitial lung disease, lung fibrosis and diminished lung functional capacity, but also to vascular involvement such as active digital ulcers. Finally, contrary to HD MPs, MPs from SSc patients stimulated the production of extracellular matrix by fibroblast, demonstrating their profibrotic potential. Conclusions: In this study, we provide evidence for a direct profibrotic role of MPs from SSc patients, underpinned by strong clinical associations in a large cohort of patients.

Lower Circulating Interferon-Gamma Is a Risk Factor for Lung Fibrosis in COVID-19 Patients.

Cytokine storm resulting from SARS-CoV-2 infection is one of the leading causes of acute respiratory distress syndrome (ARDS) and lung fibrosis. We investigated the effect of inflammatory molecules to identify any marker that is related to lung fibrosis in coronavirus disease 2019 (COVID-19). Seventy-six COVID-19 patients who were admitted to Youan Hospital between January 21 and March 20, 2020 and recovered were recruited for this study. Pulmonary fibrosis, represented as fibrotic volume on chest CT images, was computed by an artificial intelligence (AI)-assisted program. Plasma samples were collected from the participants shortly after admission, to measure the basal inflammatory molecules levels. At discharge, fibrosis was present in 46 (60.5%) patients whose plasma interferon-γ (IFN-γ) levels were twofold lower than those without fibrosis (p > 0.05). The multivariate-adjusted logistic regression analysis demonstrated the inverse association risk of having lung fibrosis and basal circulating IFN-γ levels with an estimate of 0.43 (p = 0.02). Per the 1-SD increase of basal IFN-γ level in circulation, the fibrosis volume decreased by 0.070% (p = 0.04) at the discharge of participants. The basal circulating IFN-γ levels were comparable with c-reactive protein in the discrimination of the occurrence of lung fibrosis among COVID-19 patients at discharge, unlike circulating IL-6 levels. In conclusion, these data indicate that decreased circulating IFN-γ is a risk factor of lung fibrosis in COVID-19.

Metabolomic analysis of fibrotic mice combined with public RNA-Seq human lung data reveal potential diagnostic biomarker candidates for lung fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a severe lung disease with poor survival that warrants early and precise diagnosis for timely therapeutic intervention. Despite accumulating genomic, transcriptomic, proteomic, and lipidomic data on IPF, evidence from water-soluble metabolomics is limited. To identify biomarkers for IPF from water-soluble metabolomic data, we measured the levels of various metabolites in bronchoalveolar lavage fluid (BALF) and serum samples from a bleomycin-induced murine pulmonary fibrotic model using gas chromatography/mass spectrometry. Thirty-two of 73 BALF metabolites and 29 of 74 serum metabolites were annotated. We observed that the levels of proline and methionine were higher in BALF but lower in serum than those in the control. Furthermore, analysis of public RNA-Seq data from the lungs of patients with IPF revealed that proline- and methionine-related genes were significantly upregulated compared to those in the lungs of healthy controls. These results suggest that proline and methionine may be potential biomarkers for IPF and may help to deepen our understanding of the pathophysiology of the disease. Based on our results, we propose a model capable of recapitulating the proline and methionine metabolism of fibrotic lungs, thereby providing better means for studying the disease and developing novel therapeutic strategies for IPF.

The effects of miR-27a-3p-mediated Smurf2 on bleomycin A5-induced pulmonary fibrosis in rats.

This study aimed to explore the effects of miR-27a-3p-mediated Smurf2 on bleomycin A5-induced pulmonary fibrosis in rats. Sixty clean-grade SD rats were made into models of pulmonary fibrosis induced by bleomycin A5. They were randomly divided into the control group (fed as usual), the bleomycin A5 group, and the miR-27a-3p group according to the modeling. Pathological sections and morphological observations were performed on the lung tissues of all rats, and the expression of miR-27a-3p, Smurf2 mRNA, Smurf2 protein, collagen type I (Col I), collagen type III (Col III), and related inflammatory factors in lung tissues were measured. Dual fluorescein detection was performed for miR-27a-3p and Smurf2 in lung tissues. The lung tissue of rats in the bleomycin A5 group showed obvious pathological changes. The degree of pulmonary fibrosis in the miR-27a-3p group was significantly lower than that in the bleomycin A5 group. The expression levels of Smurf2 mRNA, Smurf2 protein, Col I, Col III, and related inflammatory factors in the lung tissue of rats in the control group were notably lower than rats in the bleomycin A5 group and the miR-27a-3p group (levels of those factors in the miR-27a-3p group were lower than the bleomycin A5 group). The expression level of miR-27a-3p in the lung tissue of rats in the control group was significantly higher than that in the bleomycin A5 group and the miR-27a-3p group (miR-27a-3p level in the miR-27a-3p group was significantly higher than in the bleomycin A5 group). Results of dual fluorescein detection demonstrated that Smurf2 was a direct target gene of miR-27a-3p, and the expression of miR-27a-3p negatively associated with Smurf2. Up-regulation of miR-27a-3p expression can effectively improve the disease degree and inflammatory response in rats with pulmonary fibrosis. Its mechanism may be achieved by regulating Smurf2.