Cells In Bronchoalveolar Lavage Fluid Research Articles

Shared lung and joint T cell repertoire in early rheumatoid arthritis driven by cigarette smoking

ObjectivesSmoking has been associated with an increased risk of developing rheumatoid arthritis (RA) in individuals carrying shared epitope (SE) HLA-DRB1 alleles. Yet, little is known about the regional and systemic...

Effect of vaccination against Mycoplasma hyopneumoniae on divergent pig genetic groups

The bacterium Mycoplasma hyopneumoniae (Mhp) causes a chronic infectious respiratory disease in pigs, leading to important economic losses. This study aimed to compare the immune response of the local Piau breed and a commercial line to Mhp vaccination. For this, two phases were carried out. In the first, gene expression of toll-like receptors (TLR2, TLR4, TLR6, and TLR10) and cytokines (IL2, IL6, IL8, IL10, IL12, IL13, TNFα, and TGFβ) was assessed in porcine blood mononuclear cells (PBMC) from the two genetic groups before and after vaccination. In the second experiment, nitric oxide production, specific antibodies, and gene expression of toll-like receptors and cytokines were evaluated in bronchoalveolar lavage fluid (BALF) cells of vaccinated and unvaccinated pigs. After vaccination against Mhp, TLR2, TLR4, TLR6, TLR10, IL6, TNFα, and TGFβ expression levels were elevated in PBMC from commercial animals, and TLR6, TLR10, and TGFβ expression levels were elevated in PBMC from the Piau group. Vaccination also increased the production of Mhp-specific IgG antibodies in BALF cells in the Piau breed. Comparison of the two genetic groups revealed differences in TNFα and IL10 expression in BALF cells. These results show that Piau pigs have different immune responses to vaccination compared with commercial animals. It is worth noting that these genetic differences between both genetic groups may be related to phenotypic differences in Mhp resistance or susceptibility.

Fluconazole worsened lung inflammation, partly through lung microbiome dysbiosis in mice with ovalbumin-induced asthma.

Innate immunity in asthma may be influenced by alterations in lung microbiota, potentially affecting disease severity. This study investigates the differences in lung inflammation and microbiome between asthma-ovalbumin (OVA) administered with and without fluconazole treatment in C57BL/6 mice. Additionally, the role of inflammation was examined in an in vitro study using a pulmonary cell line. At 30 days post-OVA administration, allergic asthma mice exhibited increased levels of IgE and IL-4 in serum and lung tissue, higher pathological scores, and elevated eosinophils in bronchoalveolar lavage fluid (BALF) compared to control mice. Asthma inflammation was characterized by elevated serum IL-6, increased lung cytokines (TNF-α, IL-6, IL-10), and higher fungal abundance confirmed by polymerase chain reaction (PCR). Fluconazole-treated asthma mice displayed higher levels of cytokines in serum and lung tissue (TNF-α and IL-6), increased pathological scores, and a higher number of mononuclear cells in BALF, with undetectable fungal levels compared to untreated mice. Lung microbiome analysis revealed similarities between control and asthma mice; however, fluconazole-treated asthma mice exhibited higher Bacteroidota levels, lower Firmicutes, and reduced bacterial abundance. Pro-inflammatory cytokine production was increased in supernatants of the pulmonary cell line (NCI-H292) after co-stimulation with LPS and beta-glucan (BG) compared to LPS alone. Fluconazole treatment in OVA-induced asthma mice exacerbated inflammation, partially due to fungi and Gram-negative bacteria, as demonstrated by LPS+BG-activated pulmonary cells. Therefore, fluconazole should be reserved for treating fungal asthma rather than asthma caused by other etiologies.

MiR-144/451 attenuates lipopolysaccharide-induced lung inflammation by downregulating Rac1 and STAT-3 in macrophages.

MicroRNAs have been shown to play a critical role in lung inflammatory diseases. Here, we report that knocking out miR-144/451 in mice exacerbates lipopolysaccharide (LPS)-induced lung inflammation. The lung inflammation in mice was induced by intratracheal instillation of LPS. Loss-of-function experiments demonstrated that miR-144/451 gene knockout (KO) increased LPS-induced lung inflammation and oxidant stress compared with wild-type (WT) mice, as manifested by increased total bronchoalveolar lavage fluid cells and neutrophil counts, elevated TNF-α and IL-6 levels in bronchoalveolar lavage fluid, enhanced myeloperoxidase activity, and reduced catalase and glutathione peroxidase activity in lung tissues. We also found that LPS significantly decreased miR-451 expression in lung tissues and macrophages; while miR-451 overexpression in LPS-induced RAW264.7 cells remarkably reduced TNF-α and IL-6 levels as well as reactive oxygen species (ROS) production, suggesting a feedback loop might exist in inflammatory cells. Rac1 mRNA and protein levels were downregulated in miR-451-overexpressed RAW264.7 cells. Ex vivo stimulation experiments, performed using alveolar macrophages isolated from miR-144/451 KO mice, confirmed that Rac1 inhibitor alleviated levels of TNF-α and ROS in response to LPS stimulation compared with WT controls. Luciferase reporter assay demonstrated that STAT-3 is a direct target of miR-451. STAT-3 protein levels were elevated in miR-144/451 KO macrophages. LPS treatment also resulted in higher phosphorylation levels of STAT-3 in macrophages from KO mice than in WT cells. Our study identified miR-144/451 as an anti-inflammatory factor in LPS-induced lung inflammation that acts by downregulating Rac1 and STAT-3.

Immunological characteristics of bronchoalveolar lavage fluid and blood across connective tissue disease-associated interstitial lung diseases.

Interstitial lung disease (ILD) is a serious complication of connective tissue diseases (CTDs). The heterogeneity of ILDs reflects differences in pathogenesis among diseases. This study aimed to clarify the characteristics of CTD-ILDs via a detailed analysis of the bronchoalveolar lavage fluid (BALF) and blood immune cells. BALF and blood samples were collected from 39 Japanese patients with newly diagnosed ILD: five patients with Sjögren's syndrome (SS), eight patients with dermatomyositis (DM), six patients with rheumatoid arthritis (RA), six patients with systemic sclerosis, four patients with anti-neutrophil cytoplasmic antibody-associated vasculitis, and 10 patients with idiopathic interstitial pneumonia. We performed single-cell RNA sequencing to analyze the gene expression profiles in these patients' immune cells. In patients with SS, B cells in the BALF were increased and genes associated with the innate and acquired immunity were enriched in both the BALF and blood. In contrast, patients with DM showed an upregulation of genes associated with viral infection in both the BALF and blood. In patients with RA, neutrophils in the BALF tended to increase, and their gene expression patterns changed towards inflammation. These disease-specific characteristics may help us understand the pathogenesis for each disease and discover potential biomarkers.

Enhanced immunomodulatory properties of ovalbumin through transglutaminase and tyrosinase/caffeic acid-catalyzed crosslinking plus galactomannan conjugation alleviates allergic asthma

Ovalbumin (OVA) is the primary allergenic protein, associated with T helper 2 (Th2)-mediated allergy reactions. Here, we studied OVA’s conformational structure, digestibility, and allergenic potency upon galactomannan (Man) conjugation along with transglutaminase-catalyzed crosslinking (TG-Man/OVA) and tyrosinase/caffeic acid-catalyzed crosslinking (Tyr-Man/OVA). Enzymatic glycosylation altered OVA’s conformation and enhanced the gastrointestinal digestibility. Stimulation of bone marrow-derived dendritic cells (BMDCs) with enzymatically glycosylated OVA reduced the expression of CD40, CD80, CD86 and MHC class II molecules. Furthermore, glycosylated OVA increased IL-10 production while suppressing proinflammatory cytokine production in BMDCs. In an OVA-induced mouse asthma model, TG-Man/OVA and Tyr-Man/OVA upregulated IFN-γ and IL-10 expression and downregulated IL-4, IL-5, and IL-13 in lungs. Crosslinked OVA diminished infiltrated cells in bronchoalveolar lavage fluid and lung and attenuated eosinophilic airway inflammation. These findings offer valuable insights into the development of a novel product with improved hypoallergenic and immunomodulatory properties and hold promise in attenuating allergic diseases.

Optimisation of bronchoalveolar lavage technique for isolating alveolar macrophages in mice

Bronchoalveolar lavage (BAL) is a widely used technique to collect immune cells from the lungs, with alveolar macrophages (AMs) being the most prevalent cells in BAL fluid. AMs are vital for maintaining lung homeostasis and providing immune defence against airborne pathogens. However, in murine models, BAL procedures usually yield low numbers of AMs, thus limiting experimental design, especially when high cell counts are needed. Objective — to optimise the BAL technique in mice to maximise the collection of AMs. Materials and methods. Young and older BALB/c mice were used in the study. Bronchoalveolar lavage was performed following the method of Luckow and Lehmann (2021) with modifications. Statistical analysis was done using the Mann‑Whitney U test, with a significance level set at p<0.05. Results. Female BALB/c mice of different ages were chosen due to the frequency of their use as models of pulmonary diseases. A simplified method described by Luckow and Lehmann (2021), which avoids tracheotomy by using peroral cannula insertion, was employed. The protocol was modified by securing the cannula with a ligature to prevent BAL fluid leakage in older mice. To reduce mechanical stress on alveoli, a buffer volume of 0.6 mL was used, and the study compared two buffer variants: one at room temperature without EDTA, and another heated to 37°C with EDTA. The pre‑heated buffer with EDTA significantly increased BAL cell yields in all mice groups, confirming the importance of these optimisations for higher cell recovery. Conclusions. Our modified bronchoalveolar lavage protocol includes securing the trachea with a ligature to prevent BAL fluid leakage, reducing lavage volume to 0.6 mL to minimise lung damage, and using a 37°C solution with EDTA for improved AM recovery rates. Further studies are needed to explore the significance of other buffer components for BAL protocol optimisation, the possible age‑related differences in AM isolation in male BALB/c mice, and the strain‑specific features of the BAL technique.

Myricetin ameliorates airway inflammation and remodeling in asthma by activating Sirt1 to regulate the JNK/Smad3 pathway

BackgroundMyricetin has various biological activities and health benefits; however, its effects on airway remodeling in asthma have not been reported. PurposeWe aimed to investigate the possibility that myricetin improves airway remodeling by activating Sirt1 and has potential as a new treatment for asthma. MethodsRAW 264.7 cells were stimulated with lipopolysaccharide and co-cultured with 3T6 cells in vitro to simulate the in vivo effects of inflammation on airway remodeling. Using an ovalbumin-induced chronic asthma mouse model, we compared changes in inflammatory factors and airway remodeling-related factors under treatment with myricetin and/or the Sirt1 inhibitor EX-527 using western blotting and quantitative PCR. Expression plasmids carrying Smad3 site mutations were transfected into 3T6 cells to identify the Sirt1 deacetylation site on Smad3 protein. ResultsMyricetin significantly reduced the infiltration of airway inflammatory cells and the production of interleukin (IL)-6 and IL-5, and inhibited mucus secretion by goblet cells, collagen fiber proliferation, and the increase in inflammatory cells in bronchoalveolar lavage fluid from asthmatic mice. Results of in vitro experiments were consistent with those conducted in vivo. Exploring the mechanism of action of myricetin, we found that myricetin downregulated the levels of phosphorylated (p)-JNK, p-Smad3, and acetylated Smad3 proteins by activating Sirt1 both in vivo and in vitro. K341 was identified as the main deacetylation site of Smad3 by myricetin-activated Sirt1. ConclusionMyricetin ameliorates airway inflammation and remodeling in asthma by activating Sirt1 to regulate the JNK/Smad3 pathway.

Mitigation of allergic asthma in mice: A compound mixture comprising luteolin, arbutin, and marmesin from Gerbera Piloselloides Herba by suppression of PI3K/Akt pathway

BackgroundGerberae Piloselloidis Herba (GPH) exhibits notable efficacy in alleviating allergic asthma. Previous studies in our research have identified a mixture of luteolin, arbutin, and marmesin as effective components of GPH in treating allergic asthma. However, the underlying mechanism remains unclear. This study aims to elucidate the molecular mechanism of these active components. MethodUsing an ovalbumin (OVA)-induced allergic asthma mouse model, various treatment groups were administered, including GPH, the active component mixture (termed "Mixture") containing luteolin, arbutin, and marmesin, and a positive drug (dexamethasone, DEX). Relevant indices were assessed, including behavioral characteristics, inflammatory cell counts, cytokine levels, histopathological examination of lung tissue, apoptosis, and expression of key proteins such as Caspase-3, Bax, Bcl-2, PI3K, p-PI3K, Akt, and p-Akt. The effect of the Mixture on the PI3K/Akt signaling pathway was further verified using the PI3K inhibitor LY294002. ResultsThe Mixture significantly alleviated asthma symptoms, decreased IgE levels, cytokine levels (IL-4, IL-5, IL-13 and TNF-α), and the number of inflammatory cells in serum or bronchoalveolar lavage fluid (BALF), leading to the alleviation of lung pathological lesions. Additionally, the Mixture reduced the expression of Bax and Caspase-3 while increasing Bcl-2 expression, resulting in mitigated apoptosis in lung tissue. Furthermore, there appeared a decrease in the levels of PI3K and p-PI3K, as well as the ratio of p-Akt to Akt in the Mixture group, indicating the suppression of PI3K and Akt phosphorylation. Interestingly, the effects of the Mixture were comparable to those of GPH, LY294002, or the combination of LY294002 with the Mixture. ConclusionThe study confirms that the Mixture containing luteolin, arbutin, and marmesin indeed alleviates allergic asthma induced by OVA in mice by suppressing the PI3K/Akt signaling pathway. These findings highlight the potential of the GPH-derived Mixture as a novel therapeutic for the treatment of allergic asthma.

Therapeutic efficacy of JEW-M449, an anti-TCTP monoclonal antibody, administered via the nasal route in a BALB/c mouse model of ovalbumin-induced acute asthma

Numerous studies have highlighted the role of translationally controlled tumor protein (TCTP) as a key inflammatory mediator of asthma and allergies. Our previous study revealed that blocking the cytokine-like activity of TCTP using JEW-M449, an anti-TCTP monoclonal antibody (mAb), alleviated allergic inflammation in asthmatic mice. This study aimed to determine whether directly delivering JEW-M449 into the respiratory tract is a more effective way of mitigating airway inflammation in a mouse model of ovalbumin (OVA)-induced allergic airway inflammation than delivering this antibody via the intraperitoneal (IP) route. OVA-sensitized mice were intranasally administered JEW-M449 to enable its direct delivery to the respiratory tract before OVA challenge. We evaluated the changes in the levels of bronchoalveolar lavage fluid (BALF) cells, T helper type 2 (Th2) cytokines, OVA-specific immunoglobulin E (IgE), and histopathological alterations in the lung tissues. Intranasal (IN) administration of JEW-M449 significantly ameliorated the pathological changes associated with OVA-induced lung injury, including reduced inflammatory cell infiltration and mucus hypersecretion. Mice IN administered JEW-M449 also showed decreased OVA-mediated induction of Th2 cytokines in BALF and lung homogenates. Importantly, JEW-M449 delivered via the IN route reached the lung tissue more effectively and exerted superior anti-inflammatory effects in OVA-challenged mice than the IP-delivered JEW-M449. This study is the first to demonstrate the efficacy of directly delivering JEW-M449 anti-TCTP mAb into the respiratory tract to alleviate the asthma phenotype in a mouse model, thereby highlighting a potential delivery strategy for novel inhaled mAb therapeutics for human asthma.

The correlation between the level of cellular classification in bronchoalveolar lavage fluid of children with severe Mycoplasma pneumoniae and clinical characteristics.

The BALF of children with SMPP is predominantly neutrophilic. A lower percentage of lymphocytes is related to a higher incidence of pleural effusion, extrapulmonary manifestations and progression to RMPP, as well as a longer length of hospitalisation. • Mycoplasma pneumonia in children is relatively common in clinical practice. Bronchoalveolar lavage (BAL) is a routine clinical procedure. However, there are relatively few studies focusing on the cytomorphological analysis of cells in BAL fluid.

Oligodeoxynucleotides containing CpG motifs (CpG-ODN) restores immune regulatory functions of airway macrophages of patients with asthma.

Allergic asthma is characterized by the polarization of Th2 cells and impaired immune regulation. Macrophages occupy the largest proportion of airway immune cells. This study aims to discover the mechanism that hinders the immune regulatory functions of airway macrophages. In this study, macrophages were isolated from cells in bronchoalveolar lavage fluids (BALF) collected from asthma patients and normal control (NC) subjects. The results indicated that macrophages occupied the largest portion of the cellular components in BALF. The frequency of IL-10+ macrophage was significantly lower in asthma patients than in NC subjects. The expression of IL-10 in macrophages of BALF was associated with the levels of asthma-related parameters. The immune-suppressive functions of BALF M0 cells were defective in asthma patients. The inducibility of IL-10 expression was impaired in BALF macrophages of asthma patients, which could be restored by exposing to CpG. In conclusion, the induction of IL-10 in macrophages of BALF in asthma patients was impaired, and it could be restored by exposure to CpG.

Broncho-Vaxom Attenuates Lipopolysaccharide-Induced Inflammation in a Mouse Model of Acute Lung Injury.

Acute lung injury (ALI) is a condition associated with acute respiratory failure, resulting in significant morbidity and mortality. It involves cellular changes such as disruption of the alveolar-capillary membrane, excessive neutrophil migration, and release of inflammatory mediators. Broncho-Vaxom® (BV), a lyophilized product containing cell membrane components derived from eight bacteria commonly found in the respiratory tract, is known for its potential to reduce viral and bacterial lung infections. However, the specific effect of BV on ALI has not been clearly defined. This study explored the preventive effects of BV and its underlying mechanisms in a lipopolysaccharide (LPS)-induced ALI mouse model. Oral BV (1 mg/kg) gavage was administered one hour before the intratracheal injection of LPS to evaluate its preventive effect on the ALI model. The pre-administration of BV significantly mitigates inflammatory parameters, including the production of inflammatory mediators, macrophage infiltration, and NF-κB activation in lung tissue, and the increase in inflammatory cells in bronchoalveolar lavage fluid (BALF). Moreover, BV (3 μg/mL) pretreatment reduced the expression of M1 macrophage markers, interleukins (IL-1β, IL-6), tumor necrosis factor α, and cyclooxygenase-2, which are activated by LPS, in both mouse alveolar macrophage MH-S cells and human macrophage THP-1 cells. These findings showed that BV exhibits anti-inflammatory effects by suppressing inflammatory mediators through the NF-κB pathway, suggesting its potential to attenuate bronchial and pulmonary inflammation.

Micro-CT-assisted identification of the optimal time-window for antifibrotic treatment in a bleomycin mouse model of long-lasting pulmonary fibrosis

Idiopathic Pulmonary Fibrosis (IPF) is a debilitating and fatal lung disease characterized by the excessive formation of scar tissue and decline of lung function. Despite extensive research, only two FDA-approved drugs exist for IPF, with limited efficacy and relevant side effects. Thus, there is an urgent need for new effective therapies, whose discovery strongly relies on IPF animal models. Despite some limitations, the Bleomycin (BLM)-induced lung fibrosis mouse model is widely used for antifibrotic drug discovery and for investigating disease pathogenesis. The initial acute inflammation triggered by BLM instillation and the spontaneous fibrosis resolution that occurs after 3 weeks are the major drawbacks of this system. In the present study, we applied micro-CT technology to a longer-lasting, triple BLM administration fibrosis mouse model to define the best time-window for Nintedanib (NINT) treatment. Two different treatment regimens were examined, with a daily NINT administration from day 7 to 28 (NINT 7–28), and from day 14 to 28 (NINT 14–28). For the first time, we automatically derived both morphological and functional readouts from longitudinal micro-CT. NINT 14–28 showed significant effects on morphological parameters after just 1 week of treatment, while no modulations of these biomarkers were observed during the preceding 7–14-days period, likely due to persistent inflammation. Micro-CT morphological data evaluated on day 28 were confirmed by lung histology and bronchoalveolar lavage fluid (BALF) cells; Once again, the NINT 7–21 regimen did not provide substantial benefits over the NINT 14–28. Interestingly, both NINT treatments failed to improve micro-CT-derived functional parameters. Altogether, our findings support the need for optimized protocols in preclinical studies to expedite the drug discovery process for antifibrotic agents. This study represents a significant advancement in pulmonary fibrosis animal modeling and antifibrotic treatment understanding, with the potential for improved translatability through the concurrent structural–functional analysis offered by longitudinal micro-CT.

Rosuvastatin attenuates airway inflammation and remodeling in a chronic allergic asthma model through modulation of the AMPKα signaling pathway.

The efficacy of rosuvastatin in reducing allergic inflammation has been established. However, its potential to reduce airway remodeling has yet to be explored. This study aimed to evaluate the efficacy of rosuvastatin in reducing airway inflammation and remodeling in a mouse model of chronic allergic asthma induced by sensitization and challenge with OVA. Histology of the lung tissue and the number of inflammatory cells in bronchoalveolar lavage fluid (BALF) showed a marked decrease in airway inflammation and remodeling in mice treated with rosuvastatin, as evidenced by a decrease in goblet cell hyperplasia, collagen deposition, and smooth muscle hypertrophy. Furthermore, levels of inflammatory cytokines, angiogenesis-related factors, and OVA-specific IgE in BALF, plasma, and serum were all reduced upon treatment with rosuvastatin. Western blotting was employed to detect AMPK expression, while immunohistochemistry staining was used to observe the expression of remodeling signaling proteins such as α-SMA, TGF-β, MMP-9, and p-AMPKα in the lungs. It was found that the activity of 5'-adenosine monophosphate-activated protein kinase alpha (AMPKα) was significantly lower in the lungs of OVA-induced asthmatic mice compared to Control mice. However, the administration of rosuvastatin increased the ratio of phosphorylated AMPK to total AMPKα, thus inhibiting the formation of new blood vessels, as indicated by CD31-positive staining mainly in the sub-epithelial region. These results indicate that rosuvastatin can effectively reduce airway inflammation and remodeling in mice with chronic allergic asthma caused by OVA, likely due to the reactivation of AMPKα and a decrease in angiogenesis.

Deregulated immune cell recruitment orchestrated by c-MET impairs pulmonary inflammation and fibrosis

BackgroundPulmonary fibrosis (PF) represents the pathologic end stage of several interstitial lung diseases (ILDs) associated with high morbidity and mortality rates. However, current treatments can only delay disease progression rather than provide a cure. The role of inflammation in PF progression is well-established, but new insights into immune regulation are fundamental for developing more efficient therapies. c-MET signaling has been implicated in the migratory capacity and effector functions of immune cells. Nevertheless, the role of this signaling pathway in the context of PF-associated lung diseases remains unexplored.MethodsTo determine the influence of c-MET in immune cells in the progression of pulmonary fibrosis, we used a conditional deletion of c-Met in immune cells. To induce pulmonary fibrosis mice were administered with bleomycin (BLM) intratracheally. Over the course of 21 days, mice were assessed for weight change, and after euthanasia at different timepoints, bronchoalveolar lavage fluid cells and lung tissue were assessed for inflammation and fibrosis. Furthermore, c-MET expression was assessed in cryobiopsy sections, bronchoalveolar lavage fluid cells samples and single cell RNA-sequencing dataset from human patients with distinct interstitial lung diseases.Resultsc-MET expression was induced in lung immune cells, specifically in T cells, interstitial macrophages, and neutrophils, during the inflammatory phase of BLM-induced PF mouse model. Deletion of c-Met in immune cells correlated with earlier weight recovery and improved survival of BLM-treated mice. Moreover, the deletion of c-Met in immune cells was associated with early recruitment of the immune cell populations, normally found to express c-MET, leading to a subsequent attenuation of the cytotoxic and proinflammatory environment. Consequently, the less extensive inflammatory response, possibly coupled with tissue repair, culminated in less exacerbated fibrotic lesions. Furthermore, c-MET expression was up-regulated in lung T cells from patients with fibrosing ILD, suggesting a potential involvement of c-MET in the development of fibrosing disease.ConclusionsThese results highlight the critical contribution of c-MET signaling in immune cells to their enhanced uncontrolled recruitment and activation toward a proinflammatory and profibrotic phenotype, leading to the exacerbation of lung injury and consequent development of fibrosis.

Activation of alveolar epithelial ER stress by β-coronavirus infection disrupts surfactant homeostasis in mice: implications for COVID-19 respiratory failure.

COVID-19 syndrome is characterized by acute lung injury, hypoxemic respiratory failure, and high mortality. Alveolar type 2 (AT2) cells are essential for gas exchange, repair, and regeneration of distal lung epithelium. We have shown that the causative agent, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and other members of the β-coronavirus genus induce an endoplasmic reticulum (ER) stress response in vitro; however, the consequences for host AT2 cell function in vivo are less understood. To study this, two murine models of coronavirus infection were used-mouse hepatitis virus-1 (MHV-1) in A/J mice and a mouse-adapted SARS-CoV-2 strain. MHV-1-infected mice exhibited dose-dependent weight loss with histological evidence of distal lung injury accompanied by elevated bronchoalveolar lavage fluid (BALF) cell counts and total protein. AT2 cells showed evidence of both viral infection and increased BIP/GRP78 expression, consistent with activation of the unfolded protein response (UPR). The AT2 UPR included increased inositol-requiring enzyme 1α (IRE1α) signaling and a biphasic response in PKR-like ER kinase (PERK) signaling accompanied by marked reductions in AT2 and BALF surfactant protein (SP-B and SP-C) content, increases in surfactant surface tension, and emergence of a reprogrammed epithelial cell population (Krt8+ and Cldn4+). The loss of a homeostatic AT2 cell state was attenuated by treatment with the IRE1α inhibitor OPK-711. As a proof-of-concept, C57BL6 mice infected with mouse-adapted SARS-CoV-2 demonstrated similar lung injury and evidence of disrupted surfactant homeostasis. We conclude that lung injury from β-coronavirus infection results from an aberrant host response, activating multiple AT2 UPR stress pathways, altering surfactant metabolism/function, and changing AT2 cell state, offering a mechanistic link between SARS-CoV-2 infection, AT2 cell biology, and acute respiratory failure.NEW & NOTEWORTHY COVID-19 syndrome is characterized by hypoxemic respiratory failure and high mortality. In this report, we use two murine models to show that β-coronavirus infection produces acute lung injury, which results from an aberrant host response, activating multiple epithelial endoplasmic reticular stress pathways, disrupting pulmonary surfactant metabolism and function, and forcing emergence of an aberrant epithelial transition state. Our results offer a mechanistic link between SARS-CoV-2 infection, AT2 cell biology, and respiratory failure.

Lipocalin-2 as a prognostic marker in patients with acute exacerbation of idiopathic pulmonary fibrosis

BackgroundLipocalin-2 (LCN2) is a secretory glycoprotein upregulated by oxidative stress; moreover, patients with idiopathic pulmonary fibrosis (IPF) have shown increased LCN2 levels in bronchoalveolar lavage fluid (BALF). This study aimed to determine whether circulatory LCN2 could be a systemic biomarker in patients with IPF and to investigate the role of LCN2 in a bleomycin-induced lung injury mouse model.MethodsWe measured serum LCN2 levels in 99 patients with stable IPF, 27 patients with acute exacerbation (AE) of IPF, 51 patients with chronic hypersensitivity pneumonitis, and 67 healthy controls. Further, LCN2 expression in lung tissue was evaluated in a bleomycin-induced lung injury mouse model, and the role of LCN2 was investigated using LCN2-knockout (LCN2 -/-) mice.ResultsSerum levels of LCN2 were significantly higher in patients with AE-IPF than in the other groups. The multivariate Cox proportional hazards model showed that elevated serum LCN2 level was an independent predictor of poor survival in patients with AE-IPF. In the bleomycin-induced lung injury mouse model, a higher dose of bleomycin resulted in higher LCN2 levels and shorter survival. Bleomycin-treated LCN2 -/- mice exhibited increased BALF cell and protein levels as well as hydroxyproline content. Moreover, compared with wild-type mice, LCN2-/- mice showed higher levels of circulatory 8-isoprostane as well as lower Nrf-2, GCLC, and NQO1 expression levels in lung tissue following bleomycin administration.ConclusionsOur findings demonstrate that serum LCN2 might be a potential prognostic marker of AE-IPF. Moreover, LCN2 expression levels may reflect the severity of lung injury, and LCN2 may be a protective factor against bleomycin-induced acute lung injury and oxidative stress.

L-citrulline Mitigates Systemic Inflammation and Associated Pulmonary Vascular Remodeling in a Neonatal Rat Model of Postnatal Undernutrition

Background & Aim: Preterm infants with postnatal growth restriction and undernutrition are at increased risk of developing bronchopulmonary dysplasia (BPD), pulmonary hypertension (PH), metabolic syndrome, and sepsis. Preclinical and clinical studies report increased systemic inflammation, and lung and pancreatic histopathology in growth-restricted neonates. Safe therapies to mitigate these adverse outcomes associated with postnatal growth restriction and undernutrition in preterm infants are needed. L-citrulline is a non-essential amino acid, involved in the urea and nitric oxide cycles, that exhibits anti-inflammatory properties. This study aims to investigate whether L-citrulline may decrease systemic inflammation and improve histopathology in the lung, heart, and pancreas in a neonatal model of postnatal undernutrition. Methods: Neonatal Sprague Dawley rat pups were divided into 2 groups, normal nutrition (litter size n=12) and undernutrition (litter size n=18) by altering the litter size of the nursing dam. Body weight was measured daily and both groups received daily intraperitoneal injections of saline or L-citrulline (2.5g/kg) for 21 days. On postnatal day 21, heart, lung, and pancreatic tissue were collected for histology and mRNA analyses. Lung and pancreatic tissue were processed for qPCR to detect mRNA expression of pro-inflammatory mediators (MCP-1/CCL2, MIP-1α /CCL3, IL-6, and TNF-α). Right ventricular hypertrophy was calculated using Fulton’s index (weight of the right ventricle divided by the combined weight of the left ventricle and the intraventricular septum). Lung sections were stained with Movat Pentachrome and examined for the presence of immune cells and medial wall thickening of pulmonary arteries. In a separate group of animals, bronchoalveolar lavage fluid (BALF) and blood obtained by cardiac puncture were cytocentrifuged and stained with hematoxylin & eosin for immune cell counts. Results: Undernourished rats had a lower body weight than normally nourished rats at postnatal day 21 (n=11-17; p<0.0001). Undernourished animals had an increased number of immune cells in BALF and lung tissue and an elevated neutrophil count in the blood which were all decreased with concurrent L-citrulline treatment (n=3-4; p<0.001). L-citrulline treatment also prevented the increased mRNA expression of pro-inflammatory mediators in the lungs [MCP-1/CCL2, TNF-α, and IL-1β] (n=8; p<0.05) and pancreas [MCP-1/CCL2, MIP-1α /CCL3, IL-6, and TNF-α] (n=3; p<0.05) of undernourished animals. These animals had a greater pulmonary artery medial wall area and Fulton’s index when compared to normally nourished animals treated with saline or L-citrulline (n=3-4; p<0.001). Concurrent L-citrulline treatment in undernourished animals prevented pulmonary artery vascular remodeling and heart tissue histopathology such that the medial wall area and Fulton’s index did not differ from that of animals in control groups (n=4; p<0.01). Conclusion: L-citrulline effectively mitigates the adverse effects of postnatal undernutrition, reducing lung, pancreatic, and systemic inflammation and histopathology in the lung and heart associated with PH. As a safe, well-tolerated, and inexpensive treatment, L-citrulline presents promising therapeutic potential that could prevent short and long-term morbidities associated with growth restriction and undernutrition in preterm infants. This work was funded by the Women's Auxiliary of The Hospital for Sick Children. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Silicosis and silica-induced autoimmunity in multiple Collaborative Cross strains.

Abstract Background: The connection between pulmonary silica dust exposure and the development of systemic autoimmunity is well established. However, the extent to which genetic differences influence the severity of silica-induced autoimmunity remains unclear. Objective: Investigate the role of silica exposure on disease biomarkers (cytokines/chemokines and antinuclear antibodies (ANA)) and systemic autoimmune disease in genetically diverse Collaborative Cross recombinant inbred (CC RI) mice. Methods: Baseline serum ANA and chemokines/cytokines were assessed from 61 CC RI strains. Six CC RI strains, chosen to represent different baseline immune phenotypes, were exposed to 5 mg crystalline silica or PBS and examined 12 weeks later for serum ANA, bronchoalveolar lavage fluid cell counts, tracheobronchial lymph node and spleen weights, and histological assessment of silicosis and lupus nephritis. Results: All strains developed silicosis; however, two strains with low baseline immune activity did not develop silica-induced autoimmunity. In contrast, strains with higher baseline immune activity developed elevated ANA levels with strain variation in ANA types. One strain developed lupus nephritis, with significantly greater severity compared to controls. Conclusion: Baseline immune activity significantly influences the development of silica-induced autoimmunity and lung inflammation; however, genetics may be mediating silicosis and systemic autoimmunity independently.