Impact of Bacillus Calmette–Guérin Moreau vaccine on lung remodeling in experimental asthma

AbstractWe analyzed the effects of different administration routes and application times of the BCG-Moreau strain on airway and lung inflammation and remodeling in a murine model of allergic asthma. BALB/c mice (n=168) were divided into two groups. The first group received BCG-Moreau strain while the second group received saline using the same protocol. BCG or saline were intradermally or intranasally injected one or two months before the induction of asthma. Mice were further sensitized and challenged with ovalbumin or received saline. Twenty-four hours after the last challenge, BCG prevented the triggering of pro-inflammatory cytokines, probably by increasing Foxp3 and interleukin (IL)-10, modulating eosinophil infiltration and collagen fiber deposition, thus reducing airway hyperresponsiveness. In conclusion, BCG-Moreau prevented lung remodeling in the present model of allergic asthma, regardless of administration route and time of vaccination. These beneficial effects may be related to the increase in regulatory T cells and to IL-10 production in tandem with decreased Th2 cytokines (IL-4, IL-5, and IL-13)

The biological effects of higher and lower positive end-expiratory pressure in pulmonary and extrapulmonary acute lung injury with intra-abdominal hypertension. Crit Care

Abstract Introduction: Mechanical ventilation with high positive end-expiratory pressure (PEEP) has been used in patients with acute respiratory distress syndrome (ARDS) and intra-abdominal hypertension (IAH), but the role of PEEP in minimizing lung injury remains controversial. We hypothesized that in the presence of acute lung injury (ALI) with IAH: 1) higher PEEP levels improve pulmonary morphofunction and minimize lung injury; and 2) the biological effects of higher PEEP are more effective in extrapulmonary (exp) than pulmonary (p) ALI

Comparison between high-flow nasal oxygen (HFNO) alternated with non-invasive ventilation (NIV) and HFNO and NIV alone in patients with COVID-19: a retrospective cohort study

Abstract Background Non-invasive respiratory support (conventional oxygen therapy [COT], non-invasive ventilation [NIV], high-flow nasal oxygen [HFNO], and NIV alternated with HFNO [NIV + HFNO] may reduce the need for invasive mechanical ventilation (IMV) in patients with COVID-19. The outcome of patients treated non-invasively depends on clinical severity at admission. We assessed the need for IMV according to NIV, HFNO, and NIV + HFNO in patients with COVID-19 according to disease severity and evaluated in-hospital survival rates and hospital and intensive care unit (ICU) lengths of stay. Methods This cohort study was conducted using data collected between March 2020 and July 2021. Patients ≥ 18 years admitted to the ICU with a diagnosis of COVID-19 were included. Patients hospitalized for  50% lung damage on chest computed tomography (CT): NIV (13.3%), HFNO (15%), NIV + HFNO (71.6%) (p = 0.038); SpO2/FiO2: NIV (271 [118–365] mmHg), HFNO (317 [254–420] mmHg), NIV + HFNO (229 [102–317] mmHg) (p = 0.001); rate of IMV: NIV (26.1%, p = 0.002), HFNO (22.6%, p = 0.023), NIV + HFNO (46.8%); survival rate: HFNO (83.9%), NIV + HFNO (63.6%) (p = 0.027); ICU length of stay: NIV (8.5 [5–14] days), NIV + HFNO (15 [10–25] days (p < 0.001); hospital length of stay: NIV (13 [10–21] days), NIV + HFNO (20 [15–30] days) (p < 0.001). After adjusting for comorbidities, chest CT score and SpO2/FiO2, the risk of IMV in patients on NIV + HFNO remained high (hazard ratio, 1.88; 95% confidence interval, 1.17–3.04). Conclusions In patients with COVID-19, NIV alternating with HFNO was associated with a higher rate of IMV independent of the presence of comorbidities, chest CT score and SpO2/FiO2. Trial registration ClinicalTrials.gov identifier: NCT05579080

Focal ischemic stroke leads to lung injury and reduces alveolar macrophage phagocytic capability in rats

Abstract Background Ischemic stroke causes brain inflammation, which we postulate may result in lung damage. Several studies have focused on stroke-induced immunosuppression and lung infection; however, the possibility that strokes may trigger lung inflammation has been overlooked. We hypothesized that even focal ischemic stroke might induce acute systemic and pulmonary inflammation, thus altering respiratory parameters, lung tissue integrity, and alveolar macrophage behavior. Methods Forty-eight Wistar rats were randomly assigned to ischemic stroke (Stroke) or sham surgery (Sham). Lung function, histology, and inflammation in the lung, brain, bronchoalveolar lavage fluid (BALF), and circulating plasma were evaluated at 24 h. In vitro, alveolar macrophages from naïve rats (unstimulated) were exposed to serum or BALF from Sham or Stroke animals to elucidate possible mechanisms underlying alterations in alveolar macrophage phagocytic capability. Alveolar macrophages and epithelial and endothelial cells of Sham and Stroke animals were also isolated for evaluation of mRNA expression of interleukin (IL)-6 and tumor necrosis factor (TNF)-α. Results Twenty-four hours following ischemic stroke, the tidal volume, expiratory time, and mean inspiratory flow were increased. Compared to Sham animals, the respiratory rate and duty cycle during spontaneous breathing were reduced, but this did not affect lung mechanics during mechanical ventilation. Lungs from Stroke animals showed clear evidence of increased diffuse alveolar damage, pulmonary edema, and inflammation markers. This was associated with an increase in ultrastructural damage, as evidenced by injury to type 2 pneumocytes and endothelial cells, cellular infiltration, and enlarged basement membrane thickness. Protein levels of proinflammatory mediators were documented in the lung, brain, and plasma (TNF-α and IL-6) and in BALF (TNF-α). The phagocytic ability of macrophages was significantly reduced. Unstimulated macrophages isolated from naïve rats only upregulated expression of TNF-α and IL-6 following exposure to serum from Stroke rats. Exposure to BALF from Stroke or Sham animals did not change alveolar macrophage behavior, or gene expression of TNF-α and IL-6. IL-6 expression was increased in macrophages and endothelial cells from Stroke animals. Conclusions In rats, focal ischemic stroke is associated with brain–lung crosstalk, leading to increased pulmonary damage and inflammation, as well as reduced alveolar macrophage phagocytic capability, which seems to be promoted by systemic inflammation

Biologic Impact of Mechanical Power at High and Low Tidal Volumes in Experimental Mild Acute Respiratory Distress Syndrome

Background: The authors hypothesized that low tidal volume (V T ) would minimize ventilator-induced lung injury regardless of the degree of mechanical power. The authors investigated the impact of power, obtained by different combinations of V T and respiratory rate (RR), on ventilator-induced lung injury in experimental mild acute respiratory distress syndrome (ARDS). Methods: Forty Wistar rats received Escherichia coli lipopolysaccharide intratracheally. After 24 h, 32 rats were randomly assigned to be mechanically ventilated (2 h) with a combination of different V T (6 ml/kg and 11 ml/kg) and RR that resulted in low and high power. Power was calculated as energy (\u394P, L2 /E, L ) 7 RR (\u394P, L = transpulmonary driving pressure; E, L = lung elastance), and was threefold higher in high than in low power groups. Eight rats were not mechanically ventilated and used for molecular biology analysis. Results: Diffuse alveolar damage score, which represents the severity of edema, atelectasis, and overdistension, was increased in high V T compared to low V T , in both low (low V T : 11 [9 to 14], high V T : 18 [15 to 20]) and high (low V T : 19 [16 to 25], high V T : 29 [27 to 30]) power groups. At high V T , interleukin-6 and amphiregulin expressions were higher in high-power than in low-power groups. At high power, amphiregulin and club cell protein 16 expressions were higher in high V T than in low V T . Mechanical energy and power correlated well with diffuse alveolar damage score and interleukin-6, amphiregulin, and club cell protein 16 expression. Conclusions: In experimental mild ARDS, even at low V T , high mechanical power promoted ventilator-induced lung injury. To minimize ventilator-induced lung injury, low V T should be combined with low power

Effects of different fluid management on lung and kidney during pressure‐controlled and pressure‐support ventilation in experimental acute lung injury

Abstract Optimal fluid management is critical during mechanical ventilation to mitigate lung damage. Under normovolemia and protective ventilation, pulmonary tensile stress during pressure‐support ventilation (PSV) results in comparable lung protection to compressive stress during pressure‐controlled ventilation (PCV) in experimental acute lung injury (ALI). It is not yet known whether tensile stress can lead to comparable protection to compressive stress in ALI under a liberal fluid strategy (LF). A conservative fluid strategy (CF) was compared with LF during PSV and PCV on lungs and kidneys in an established model of ALI. Twenty‐eight male Wistar rats received endotoxin intratracheally. After 24 h, they were treated with CF (minimum volume of Ringer's lactate to maintain normovolemia and mean arterial pressure ≥70 mmHg) or LF (~4 times higher than CF) combined with PSV or PCV (VT = 6 ml/kg, PEEP = 3 cmH2O) for 1 h. Nonventilated animals (n = 4) were used for molecular biology analyses. CF‐PSV compared with LF‐PSV: (1) decreased the diffuse alveolar damage score (10 [7.8–12] vs. 25 [23–31.5], p = 0.006), mainly due to edema in axial and alveolar parenchyma; (2) increased birefringence for occludin and claudin‐4 in lung tissue and expression of zonula‐occludens‐1 and metalloproteinase‐9 in lung. LF compared with CF reduced neutrophil gelatinase‐associated lipocalin and interleukin‐6 expression in the kidneys in PSV and PCV. In conclusion, CF compared with LF combined with PSV yielded less lung epithelial cell damage in the current model of ALI. However, LF compared with CF resulted in less kidney injury markers, regardless of the ventilatory strategy

Respiratory and systemic effects of LASSBio596 plus surfactant in experimental acute respiratory distress syndrome

Background/Aims: Exogenous surfactant has been proposed as adjunctive therapy for acute respiratory distress syndrome (ARDS), but it is inactivated by different factors present in the alveolar space. We hypothesized that co-administration of LASSBio596, a molecule with significant anti-inflammatory properties, and exogenous surfactant could reduce lung inflammation, thus enabling the surfactant to reduce edema and improve lung function, in experimental ARDS. Methods: ARDS was induced by cecal ligation and puncture surgery in BALB/c mice. A sham-operated group was used as control (CTRL). After surgery (6 hours), CTRL and ARDS animals were assigned to receive: (1) sterile saline solution; (2) LASSBio596; (3) exogenous surfactant or (4) LASSBio596 plus exogenous surfactant (n = 22/group). Results: Regardless of exogenous surfactant administration, LASSBio596 improved survival rate and reduced collagen fiber content, total number of cells and neutrophils in PLF and blood, cell apoptosis, protein content in BALF, and urea and creatinine levels. LASSBio596 plus surfactant yielded all of the aforementioned beneficial effects, as well as increased BALF lipid content and reduced surface tension. Conclusion: LASSBio596 exhibited major anti-inflammatory and anti-fibrogenic effects in experimental sepsis-induced ARDS. Its association with surfactant may provide further advantages, potentially by reducing surface tension