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Introduction: Programmed cell death-ligand 1 (PD-L1) is a biomarker for prediction of the clinical efficacy of immune checkpoint inhibitors in various cancer types. The role of cytokines in regulation of PD-L1 expression in tumor cells has not been fully characterized, however. Here we show that interleukin-1b (IL-1b) plays a key role in regulation of PD-L1 expression in non-small cell lung cancer (NSCLC). Methods: We performed comprehensive screening of cytokine gene expression in NSCLC tissue using available single-cell RNA-Sequence data. Then we examined the role of IL-1b in vitro to elucidate its induction of PD-L1 on NSCLC cells. Results: The IL-1b gene is highly expressed in the tumor microenvironment, particularly in macrophages. The combination of IL-1b and interferon-g (IFN-g) induced a synergistic increase in PD-L1 expression in NSCLC cell lines. IL-1b and IFN-g also cooperatively activated mitogen-activated protein kinase (MAPK) signaling and promoted the binding of downstream transcription factors to the PD-L1 gene promoter. Furthermore, inhibitors of MAPK signaling blocked upregulation of PD-L1 by IL-1b and IFN-g. Discussion:Our study reports high levels of IL-1b in the tumor microenvironment may cooperate with IFN-g to induce maximal PD-L1 expression in tumor cells via activation of MAPK signaling, with the IL-1b-MAPK axis being a promising therapeutic target for attenuation of PD-L1-mediated suppression of antitumor immunity. [ABSTRACT FROM AUTHOR]

The quantification of airway compliance (Caw) is essential to the study of airway alterations in disease models. However, the required measurements of airway pressure and volume are difficult to acquire in mice. We hypothesized that the inflation limb of full-range pressure-volume (PV) curves could be used to quantify Caw, as it contains a segment where only the airway tree is distended. The study objective was to assess the feasibility of the approach by analysis of full-range PV curves previously collected in three mouse models: an elastase model of emphysema, a genetic model spontaneously developing emphysema (leukotriene C4 synthase knockout; LTC4S-KO), and a bleomycin model of lung fibrosis. Attempts to validate results included Caw change relative to respiratory system compliance (ΔCaw/ΔC), the minute work of breathing (mWOB), and the elastance at 20.5 Hz (Ers_20.5) from prior respiratory mechanics measurements in the same subjects. Caw was estimated at 3% of total compliance in healthy mice or 2.3 ± 1 μL/cmH2O (n = 17). The technique detected changes in models of respiratory obstructive and restrictive diseases relative to control mice as well as differences in the two emphysema models studied. The changes in Caw were consistent with those seen in ΔCaw/ΔC, mWOB, or Ers_20.5, with some variations according to the model, as well as with results reported in the literature in humans and mice. Direct Caw measurements in subjects as small as mice could prove useful to further characterize other respiratory disease models associated with airway remodeling or to assess treatment effects. [ABSTRACT FROM AUTHOR]

Asthma and chronic obstructive pulmonary disease (COPD), chronic airway inflammatory diseases characterized by airflow limitation, have different etiologies and pathophysiologies. Asthma-COPD Overlap (ACO) has recently been used for patients with mixed asthma and COPD. The pathophysiological mechanisms of ACO have not been clearly understood due to the lack of an appropriate murine model. To investigate its pathophysiology, we examined a murine model by allergen challenge in surfactant protein-D (SP-D)-deficient mice that spontaneously developed pulmonary emphysema. SP-D-deficient mice were sensitized and challenged by ovalbumin (OVA). Lungs and bronchoalveolar lavage fluid (BALF) were collected for analysis, and static lung compliance and airway hyperresponsiveness (AHR) were measured 48 h after the last OVA challenge. In SP-D-deficient, naiıve, or OVA-challenged mice, the mean linear intercept and static lung compliance were increased compared with wild-type (WT) mice. There was no significant difference in goblet cell hyperplasia and the gene expression of Mucin 5AC (MUC5AC) between SPD- deficient and WT OVA-challenged mice. In SP-D-deficient OVA-challenged mice, airway hyperresponsiveness was significantly enhanced despite the lower eosinophil count and the concentration of interleukin (IL)-5 and IL-13 in BALF compared with WT OVA-challenged mice at 120 ventilations per minute. When mice were ventilated at a lower ventilation frequency of 100 ventilations per minute, elevated airway hyperresponsiveness in SP-D-deficient OVA-challenged mice was diminished. This model of emphysematous change with allergic airway inflammation raises the possibility that frequency-dependent airway hyperresponsiveness may be involved in the pathophysiology of ACO. [ABSTRACT FROM AUTHOR]

GPCRs are involved in numerous physiologic functions and are important drug targets. Although the epithelial barrier is important for protection from invading pathogens, the correlation between GPCRs and epithelial barrier function remains unknown. Leukotriene B4 (LTB4) receptor type 2 (BLT2), mainly expressed in epithelial cells, is a GPCR for 12(S)-hydroxyheptadeca-5Z,8E,10E-trienoic acid (12-HHT) and LTB4. In our study, BLT2 localized at the lateral membrane in BLT2-overexpressing Madin-Darby canine kidney (MDCK) II cells and in the small intestine of BLT2-transgenic mice. BLT2-deficient mice exhibited higher transepidermal water loss and were more sensitive to epicutaneous sensitization. MDCK-BLT2 cells recovered transepithelial electrical resistance (TER) after a calcium switch faster than did MDCK-Mock cells, and 12-HHT stimulation accelerated TER recovery only in MDCK-BLT2 cells. Quantitative PCR and immunoblot analyses revealed that the 12-HHT/BLT2 axis up-regulated claudin-4 (CLDN4) expression in MDCK-BLT2 cells and human primary keratinocytes, and CLDN4 knockdown abolished 12-HHT-dependent TER recovery. Acceleration of TER recovery and induction of CLDN4 expression by 12-HHT stimulation were abolished by inhibition of Gai protein or p38 MAPK. These results show that 12-HHT/BLT2 enhances epithelial barrier function by increasing CLDN4 expression viathe Gai protein-p38 MAPK pathway. [ABSTRACT FROM AUTHOR]