Pirfenidone alleviates lung ischemia-reperfusion injury in a rat model

Hemopexin alleviates sterile inflammation in ischemia-reperfusion-induced lung injury

Introduction

Pulmonary ischemia-reperfusion (IR) injury (IRI) plays a significant role in various lung disorders and is a key factor in the development of primary graft dysfunction following lung transplantation. Hemopexin (Hx) is the major serum scavenger protein for heme, which is a prooxidant and pro-inflammatory compound. In the current study, we hypothesized that Hx could confer beneficial effects in sterile inflammation induced by IR-mediated lung injury.

Methods

To examine this hypothesis, we administered Hx in an experimental mouse model of unilateral lung IRI.

Results

Our results demonstrate that treatment with Hx alleviated histopathological signs of inflammation in ischemic lungs, as evidenced by a reduction in the number of infiltrating neutrophils and decreased levels of perivascular edema. In addition, thrombotic vaso-occlusion in pulmonary blood vessels of IRI lungs was reduced by Hx. Immunohistochemical analysis revealed that Hx inhibited the up-regulation of heme oxygenase-1, an enzyme highly induced by heme, in ischemic lungs. Finally, Hx administration caused a decrease in the levels of circulating B- and CD8+ T-lymphocytes in the peripheral blood of mice with pulmonary IRI.

Conclusion

These findings suggest that the serum heme scavenger protein Hx holds therapeutic promise in alleviating lung IRI-mediated sterile inflammation. Thus, Hx may represent a preemptive therapeutic approach in IR-related lung disorders such as primary graft dysfunction in lung transplantation.

Metformin attenuates lung ischemia-reperfusion injury and necroptosis through AMPK pathway in type 2 diabetic recipient rats

BACKGROUND

Diabetes mellitus (DM) can aggravate lung ischemia-reperfusion (I/R) injury and is a significant risk factor for recipient mortality after lung transplantation. Metformin protects against I/R injury in a variety of organs. However, the effect of metformin on diabetic lung I/R injury remains unclear. Therefore, this study aimed to observe the effect and mechanism of metformin on lung I/R injury following lung transplantation in type 2 diabetic rats.

METHODS

Sprague-Dawley rats were randomly divided into the following six groups: the control + sham group (CS group), the control + I/R group (CIR group), the DM + sham group (DS group), the DM + I/R group (DIR group), the DM + I/R + metformin group (DIRM group) and the DM + I/R + metformin + Compound C group (DIRMC group). Control and diabetic rats underwent the sham operation or left lung transplantation operation. Lung function, alveolar capillary permeability, inflammatory response, oxidative stress, necroptosis and the p-AMPK/AMPK ratio were determined after 24 h of reperfusion.

RESULTS

Compared with the CIR group, the DIR group exhibited decreased lung function, increased alveolar capillary permeability, inflammatory responses, oxidative stress and necroptosis, but decreased the p-AMPK/AMPK ratio. Metformin improved the function of lung grafts, decreased alveolar capillary permeability, inflammatory responses, oxidative stress and necroptosis, and increased the p-AMPK/AMPK ratio. In contrast, the protective effects of metformin were abrogated by Compound C.

CONCLUSIONS

Metformin attenuates lung I/R injury and necroptosis through AMPK pathway in type 2 diabetic lung transplant recipient rats.

Penehyclidine hydrochloride alleviates lung ischemia-reperfusion injury by inhibiting pyroptosis

OBJECTIVE

The aim of this research was to examine how penehyclidine hydrochloride (PHC) impacts the occurrence of pyroptosis in lung tissue cells within a rat model of lung ischemia-reperfusion injury.

METHODS

Twenty-four Sprague Dawley (SD) rats, weighing 250 g to 270 g, were randomly distributed into three distinct groups as outlined below: a sham operation group (S group), a control group (C group), and a test group (PHC group). Rats in the PHC group received a preliminary intravenous injection of PHC at a dose of 3 mg/kg. At the conclusion of the experiment, lung tissue and blood samples were collected and properly stored for subsequent analysis. The levels of malondialdehyde, superoxide dismutase, and myeloperoxidase in the lung tissue, as well as IL-18 and IL-1β in the blood serum, were assessed using an Elisa kit. Pyroptosis-related proteins, including Caspase1 p20, GSDMD-N, and NLRP3, were detected through the western blot method. Additionally, the dry-to-wet ratio (D/W) of the lung tissue and the findings from the blood gas analysis were also documented.

RESULTS

In contrast to the control group, the PHC group showed enhancements in oxygenation metrics, reductions in oxidative stress and inflammatory reactions, and a decrease in lung injury. Additionally, the PHC group exhibited lowered levels of pyroptosis-associated proteins, including the N-terminal segment of gasdermin D (GSDMD-N), caspase-1p20, and nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3).

CONCLUSION

Pre-administration of PHC has the potential to mitigate lung ischemia-reperfusion injuries by suppressing the pyroptosis of lung tissue cells, diminishing inflammatory reactions, and enhancing lung function. The primary mechanism behind anti-pyroptotic effect of PHC appears to involve the inhibition of oxidative stress.

Rebaudioside B Attenuates Lung Ischemia-reperfusion Injury Associated Apoptosis and Inflammation

OBJECTIVE

At present, no proven effective treatment is available for Lung Ischemiareperfusion Injury (LIRI). Natural compounds offer promising prospects for developing new drugs to address various diseases. This study sought to explore the potential of Rebaudioside B (Reb B) as a treatment compound for LIRI, both in vivo and in vitro.

METHODS

This study involved utilizing the human pulmonary alveolar cell line A549, consisting of epithelial type II cells, subjected to Oxygen-glucose Deprivation/recovery (OGD/R) for highthroughput in vitro cell viability screening. The aim was to identify the most promising candidate compounds. Additionally, an in vivo rat model of lung ischemia-reperfusion was employed to evaluate the potential protective effects of Reb B.

RESULTS

Through high-throughput screening, Reb B emerged as the most promising natural compound among those tested. In the A549 OGD/R models, Reb B exhibited a capacity to enhance cell viability by mitigating apoptosis. In the in vivo LIRI model, pre-treatment with Reb B notably decreased apoptotic cells, perivascular edema, and neutrophil infiltration within lung tissues. Furthermore, Reb B demonstrated its ability to attenuate lung inflammation associated with LIRI primarily by elevating IL-10 levels while reducing levels of IL-6, IL-8, and TNF-α.

CONCLUSION

The comprehensive outcomes strongly suggest Reb B's potential as a protective agent against LIRI. This effect is attributed to its inhibition of the mitochondrial apoptotic pathway and its ability to mitigate the inflammatory response.

Antifibrotic effects of sodium-glucose cotransporter-2 inhibitors: A comprehensive review

BACKGROUND AND AIMS

Scar tissue accumulation in organs is the underlying cause of many fibrotic diseases. Due to the extensive array of organs affected, the long-term nature of fibrotic processes and the large number of people who suffer from the negative impact of these diseases, they constitute a serious health problem for modern medicine and a huge economic burden on society. Sodium-glucose cotransporter-2 inhibitors (SGLT2is) are a relatively new class of anti-diabetic pharmaceuticals that offer additional benefits over and above their glucose-lowering properties; these medications modulate a variety of diseases, including fibrosis. Herein, we have collated and analyzed all available research on SGLT2is and their effects on organ fibrosis, together with providing a proposed explanation as to the underlying mechanisms.

METHODS

PubMed, ScienceDirect, Google Scholar and Scopus were searched spanning the period from 2012 until April 2023 to find relevant articles describing the antifibrotic effects of SGLT2is.

RESULTS

The majority of reports have shown that SGLT2is are protective against lung, liver, heart and kidney fibrosis as well as arterial stiffness. According to the results of clinical trials and animal studies, many SGLT2 inhibitors are promising candidates for the treatment of fibrosis. Recent studies have demonstrated that SGLT2is affect an array of cellular processes, including hypoxia, inflammation, oxidative stress, the renin-angiotensin system and metabolic activities, all of which have been linked to fibrosis.

CONCLUSION

Extensive evidence indicates that SGLT2is are promising treatments for fibrosis, demonstrating protective effects in various organs and influencing key cellular processes linked to fibrosis.

Effect of antifibrotic agents on postoperative complications after lung transplantation for idiopathic pulmonary fibrosis

BACKGROUND

Antifibrotic agents (AFAs) are now standard-of-care for idiopathic pulmonary fibrosis (IPF). Concerns have arisen about the safety of these drugs in patients undergoing lung transplantation (LTx).

METHODS

We performed a multi-centre, nationwide, retrospective, observational study of French IPF patients undergoing LTx between 2011 and 2018 to determine whether maintaining AFAs in the peri-operative period leads to increased bronchial anastomoses issues, delay in skin healing and haemorrhagic complications. We compared the incidence of post-operative complications and the survival of patients according to AFA exposure.

RESULTS

Among 205 patients who underwent LTx for IPF during the study period, 58 (28%) had received AFAs within 4 weeks before LTx (AFA group): pirfenidone in 37 (18.0%) and nintedanib in 21 (10.2%). The median duration of AFA treatment before LTx was 13.8 (5.6-24) months. The AFA and control groups did not significantly differ in airway, bleeding or skin healing complications (p = 0.91, p = 0.12 and p = 0.70, respectively). Primary graft dysfunction was less frequent in the AFA than control group (26% vs. 43%, p = 0.02), and the 90-day mortality was lower (7% vs. 18%, p = 0.046).

CONCLUSIONS

AFA therapy did not increase airway, bleeding or wound post-operative complications after LTx and could be associated with reduced rates of primary graft dysfunction and 90-day mortality.

Early plasma proteomic biomarkers and prediction model of acute respiratory distress syndrome after cardiopulmonary bypass: a prospective nested cohort study

BACKGROUND

Early recognition of the risk of acute respiratory distress syndrome (ARDS) after cardiopulmonary bypass (CPB) may improve clinical outcomes. The main objective of this study was to identify proteomic biomarkers and develop an early prediction model for CPB-ARDS.

METHODS

The authors conducted three prospective nested cohort studies of all consecutive patients undergoing cardiac surgery with CPB at Union Hospital of Tongji Medical College Hospital. Plasma proteomic profiling was performed in ARDS patients and matched controls (Cohort 1, April 2021-July 2021) at multiple timepoints: before CPB (T1), at the end of CPB (T2), and 24 h after CPB (T3). Then, for Cohort 2 (August 2021-July 2022), biomarker expression was measured and verified in the plasma. Furthermore, lung ischemia/reperfusion injury (LIRI) models and sham-operation were established in 50 rats to explore the tissue-level expression of biomarkers identified in the aforementioned clinical cohort. Subsequently, a machine learning-based prediction model incorporating protein and clinical predictors from Cohort 2 for CPB-ARDS was developed and internally validated. Model performance was externally validated on Cohort 3 (January 2023-March 2023).

RESULTS

A total of 709 proteins were identified, with 9, 29, and 35 altered proteins between ARDS cases and controls at T1, T2, and T3, respectively, in Cohort 1. Following quantitative verification of several predictive proteins in Cohort 2, higher levels of thioredoxin domain containing 5 (TXNDC5), cathepsin L (CTSL), and NPC intracellular cholesterol transporter 2 (NPC2) at T2 were observed in CPB-ARDS patients. A dynamic online predictive nomogram was developed based on three proteins (TXNDC5, CTSL, and NPC2) and two clinical risk factors (CPB time and massive blood transfusion), with excellent performance (precision: 83.33%, sensitivity: 93.33%, specificity: 61.16%, and F1 score: 85.05%). The mean area under the receiver operating characteristics curve (AUC) of the model after 10-fold cross-validation was 0.839 (95% CI: 0.824-0.855). Model discrimination and calibration were maintained during external validation dataset testing, with an AUC of 0.820 (95% CI: 0.685-0.955) and a Brier Score of 0.177 (95% CI: 0.147-0.206). Moreover, the considerably overexpressed TXNDC5 and CTSL proteins identified in the plasma of patients with CPB-ARDS, exhibited a significant upregulation in the lung tissue of LIRI rats.

CONCLUSIONS

This study identified several novel predictive biomarkers, developed and validated a practical prediction tool using biomarker and clinical factor combinations for individual prediction of CPB-ARDS risk. Assessing the plasma TXNDC5, CTSL, and NPC2 levels might identify patients who warrant closer follow-up and intensified therapy for ARDS prevention following major surgery.

Inhibition of autophagy and RIP1/RIP3/MLKL-mediated necroptosis by edaravone attenuates blood spinal cord barrier disruption following spinal cord injury

The disruption of the blood spinal cord barrier (BSCB) after spinal cord injury (SCI) can trigger secondary tissue damage. Edaravone is likely to protect the BSCB as a free radical scavenger, whereas it has been rarely reported thus far. In this study, the protective effect of edaravone was investigated with the use of compression spinal cord injured rats and human brain microvascular endothelial cells (HBMECs) injury. As indicated by the result of this study, edaravone treatment facilitated functional recovery after rats were subjected to SCI, ameliorated the vascular damage, and up-regulated the expression of BSCB-associated proteins. In vitro results, edaravone improved HBMECs viability, restored intercellular junctions, and promoted cellular angiogenic activities. It is noteworthy that autophagy was activated and RIP1/RIP3/MLKL phosphorylation was notably up-regulated. However, edaravone treatment exhibited the capability of mitigating above-mentioned tendency in vivo and in vitro. Moreover, rapamycin (Rapa) treatment deteriorated the protective effect of edaravone while aggravating the phosphorylation of RIP1/RIP3/MLKL expression. In the model of necrotic activator-induced HBMECs, autophagic expression was increased, whereas edaravone prevented autophagy and phosphorylation of RIP1/RIP3/MLKL. In general, our results suggested that edaravone is capable of reducing the destruction of BSCB and promoting functional recovery after SCI. The possible underlying mechanism is that edaravone is capable of protecting angiogenic activity and improving autophagy and the phosphorylation of RIP1/RIP3/MLKL, as well as their mutual deterioration. Accordingly, edaravone can be a favorable option for the treatment of SCI.

Impact of Antifibrotic Treatment on Postoperative Complications in Patients with Interstitial Lung Diseases Undergoing Lung Transplantation: A Systematic Review and Meta-Analysis

Antifibrotic treatment has been approved for reducing disease progression in fibrotic interstitial lung disease (ILD). As a result of increased bleeding risk, some experts suggest cessation of antifibrotics prior to lung transplantation (LT). However, extensive knowledge regarding the impact of antifibrotic treatment on postoperative complications remains unclear. We performed a comprehensive search of several databases from their inception through to 30 September 2021. Original studies were included in the final analysis if they compared postoperative complications, including surgical wound dehiscence, anastomosis complication, bleeding complications, and primary graft dysfunction, between those with and without antifibrotic treatment undergoing LT. Of 563 retrieved studies, 6 studies were included in the final analysis. A total of 543 ILD patients completing LT were included, with 161 patients continuing antifibrotic treatment up to the time of LT and 382 without prior treatment. Antifibrotic treatment was not significantly associated with surgical wound dehiscence (RR 1.05; 95% CI, 0.31-3.60; I² = 0%), anastomotic complications (RR 0.88; 95% CI, 0.37-2.12; I² = 31%), bleeding complications (RR 0.76; 95% CI, 0.33-1.76; I² = 0%), or primary graft dysfunction (RR 0.87; 95% CI, 0.59-1.29; I² = 0%). Finally, continuing antifibrotic treatment prior to LT was not significantly associated with decreased 1-year mortality (RR 0.80; 95% CI, 0.41-1.58; I² = 0%). Our study suggests a similar risk of postoperative complications in ILD patients undergoing LT who received antifibrotic treatment compared to those not on antifibrotic therapy.

Aquaporin-1 inhibition exacerbates ischemia-reperfusion-induced lung injury in mouse

BACKGROUND

Ischemia-reperfusion injury (IRI), which involves severe inflammation and edema, is an inevitable feature of the lung transplantation process and leads to primary graft dysfunction (PGD). The activation of aquaporin 1 (AQP1) modulates fluid transport in the alveolar space. The current study investigated the role of AQP1 in ischemia-reperfusion (IR)-induced lung injury.

METHODS

A mouse model of lung IR was established by clamping the left lung hilar for 1 h and released for reperfusion for 24 h. The AQP1 inhibitor acetazolamide (AZA) was administered 3 days before lung ischemia with a dose of 100 mg/kg per day via gavage. Lung injury was evaluated using the ratio of wet-to-dry weight, peripheral bronchial epithelial thickness, degree of angioedema, acute lung injury score, neutrophil infiltration, and cytokine concentrations in bronchoalveolar lavage fluid.

RESULTS

Compared with sham treatment, ischemia with no reperfusion (IR 0h) and ischemia with reperfusion for 24 h (IR 24 h) significantly upregulated AQP1 expression, increased the wet/dry weight ratio, angioedema, neutrophil infiltration and cytokine production (interleukin -6 and tumor necrosis factor -α) and thickened the peripheral bronchial epithelium. AZA exacerbated inflammation and pulmonary edema.

CONCLUSION

AQP1 may exert a protective effect against IR-induced lung injury, which could be attributed to alleviating pulmonary edema and inflammation. AQP1 upregulation might be a potential application to alleviate lung IRI and decrease the incidence of PGD.

Acteoside alleviates dextran sulphate sodium‑induced ulcerative colitis via regulation of the HO‑1/HMGB1 signaling pathway

Ulcerative colitis (UC) is a significant burden on human health, and the elucidation of the mechanism by which it develops has potential for the prevention and treatment of UC. It has been reported that acteoside (ACT) exhibits strong anti‑inflammatory activity. In the present study, it was hypothesized that ACT may exert a protective effect against UC. The effects of ACT on inflammation, oxidative stress and apoptosis were evaluated using dextran sulphate sodium (DSS)‑treated mice and DSS‑treated human colorectal adenocarcinoma Caco‑2 cells, which have an epithelial morphology. The results demonstrated that the ACT‑treated mice with DSS‑induced UC exhibited significantly reduced colon inflammation, as demonstrated by a reversal in body weight loss, colon shortening, disease activity index score, inflammation, oxidative stress and colonic barrier dysfunction. Further in vivo experiments demonstrated that ACT inhibited DSS‑induced apoptosis in colon tissues, as demonstrated by the results of the TUNEL assay and the altered protein expression levels of Bax, cleaved caspase‑3 and Bcl‑2. Furthermore, DSS significantly stimulated the protein expression levels of high mobility group box 1 protein (HMGB1), which serves a central role in the initiation and progression of UC, an effect which was markedly inhibited by ACT. Finally, DSS significantly decreased the protein expression levels of heme oxygenase‑1 (HO‑1) in colon tissues and the effect of ACT on GSH, apoptotic proteins and HMGB1 was markedly attenuated in the presence of the HO‑1 inhibitor tin protoporphyrin. In conclusion, ACT ameliorated colon inflammation through HMGB1 inhibition in a HO‑1‑dependent manner.

Right lung transplantation with a left-to-right inverted anastomosis in a rat model

Objective

Right lung transplantation in rats has been attempted occasionally, but the technical complexity makes it challenging to apply routinely. Additionally, basic research on inverted lobar lung transplantation is scarce because of the lack of a cost-effective experimental model. We first reported right lung transplantation in a rat model using left-to-right inverted anastomosis to imitate the principle of clinically inverted lung transplantation.

Methods

Right lung transplantation was performed in 10 consecutive rats. By using a 3-cuff technique, the left lung of the donor rat was implanted into the right thoracic cavity of the recipient rat. The rat lung graft was rotated 180° along the vertical axis to achieve anatomic matching of right hilar structures. Another 10 consecutive rats had received orthotopic left lung transplantation as a control.

Results

All lung transplantation procedures were technically successful without intraoperative failure. One rat (10%) died of full pulmonary atelectasis after right lung transplantation, whereas all rats survived after left lung transplantation. No significant difference was observed in heart-lung block retrieval (8.6 ± 0.8 vs 8.4 ± 0.9 minutes), cuff preparation (8.3 ± 0.9 vs 8.7 ± 0.9 minutes), or total procedure time (58.2 ± 2.6 vs 56.6 ± 2.1 minutes) between the right lung transplantation and standard left lung transplantation groups (P > .05), although the cold ischemia time (14.2 ± 0.9 vs 25.5 ± 1.7 minutes) and warm ischemia time (19.8 ± 1.5 vs 13.7 ± 1.8 minutes) were different (P < .001).

Conclusions

Right lung transplantation with a left-to-right inverted anastomosis in a rat model is technically easy to master, expeditious, and reproducible. It can potentially imitate the principle of clinically inverted lung transplantation and become an alternative to standard left lung transplantation.

Effect of Different Doses of Propofol on Pulmonary Function and Inflammatory Response in Patients with Lung Ischemia Reperfusion Injury Induced by One-Lung Ventilation Based on Big Data Analysis

Objective

To analyze the effect of different doses of propofol on pulmonary function and inflammatory response in patients with lung ischemia reperfusion injury (LIRI) induced by one-lung ventilation (OLV) based on big data analysis.

Methods

A retrospective study was performed on 105 patients who underwent lobectomy in our hospital (January 2018 to January 2022). According to the doses of propofol, they were split into low-dose group (LDG), middle-dose group (MDG), and high-dose group (HDG), which received the continuous micropump infusion of propofol at the doses of 2 mg/(kg·h), 5 mg/(kg·h), and 10 mg/(kg·h) after induction, respectively, with 35 cases in each group. The indexes, such as the pulmonary function and inflammatory factors of patients, at different times were compared. The logistic regression analysis was performed according to the occurrence of LIRI.

Results

With no notable difference at T0 among the three groups (P > 0.05), the Cdyn levels significantly decreased at T1 (P < 0.05) and gradually increased at T2. The Cdyn levels at T1 and T2 were remarkably higher in HDG and MDG than in LDG (P < 0.05). With no notable differences at T0 and T1 among the three groups (P > 0.05), the P_A-aO₂ levels and RI values at T2 in MDG and HDG were lower compared with LDG (P < 0.05). The RI values at T1 and T2 in HDG were higher compared with MDG, with no obvious difference (P > 0.05). The OI levels at T1 and T2 in HDG were lower compared with the other two groups (P < 0.05), and the OI levels at T1, T2, and T3 in LDG were higher compared with MDG, with no obvious difference (P > 0.05). The TNF-α and ICAM-1 levels at T1 and T2 in MDG and HDG were lower compared with LDG, with no obvious difference between MDG and HDG (P > 0.05). Compared with LDG, the MDG and HDG at T1 and T2 had lower MDA levels (P < 0.05) and higher SOD levels (P < 0.05). Logistic regression analysis showed that Cdyn, P_A-aO₂, and OLV time were independent risk factors for LIRI in patients undergoing lobectomy.

Conclusion

Propofol has a good protective effect on lung function in patients with OLV-induced LIRI. Appropriately increasing the dose of propofol can effectively improve the local cerebral hypoxia and lung compliance of patients and reduce the inflammatory response and oxidative stress response, with 5 mg/(kg·h) as the clinical reference. Preoperative assessment and preparation should be made for patients, close attention should be paid to risk factors, such as Cdyn and P_A-aO₂, and OLV time should be controlled.

Lidocaine attenuates hypoxia/reoxygenation‑induced inflammation, apoptosis and ferroptosis in lung epithelial cells by regulating the p38 MAPK pathway

Lung ischemia-reperfusion (I/R) injury poses a serious threat to human health, worldwide. The current study aimed to determine the role of lidocaine in A549 cells, in addition to the involvement of the p38 MAPK pathway. Oxygen deprivation/reoxygenation-induced A549 cells were utilized to simulate I/R injury in vitro. Cell viability and apoptosis were detected using MTT and TUNEL assays, respectively. The levels of IL-6, IL-8, TNF-α, malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase, iron and reactive oxygen species (ROS) were measured using corresponding commercial kits. The corresponding protein expression levels were also measured using western blotting. Moreover, a monolayer cell paracellular permeability assay was performed to determine the permeability of A549 cells. The results demonstrated that, whilst lidocaine had no influence on untreated A549 cells, it significantly increased the viability of hypoxia/reoxygenation (H/R)-induced A549 cells. A549 cell apoptosis and the release of inflammatory cytokines in the H/R group were decreased after the addition of lidocaine. When compared with the H/R group, increased MDA level and decreased SOD level were observed in H/R-induced A549 cells following lidocaine treatment. In addition, the permeability of H/R-induced A549 cells was markedly decreased following lidocaine treatment. Compared with the H/R group, the expression levels of tight junction and ferroptosis-related proteins were significantly upregulated by lidocaine, whereas the expression of transferrin was downregulated. However, p79350, an agonist of p38, reversed the effects of lidocaine on H/R-induced A549 cells. In conclusion, lidocaine exerted a protective role in HR-induced lung epithelial cell injury, which may serve as a potential agent for the treatment of patients with lung I/R injury.

Dexmedetomidine Alleviates Lung Oxidative Stress Injury Induced by Ischemia-Reperfusion in Diabetic Rats via the Nrf2-Sulfiredoxin1 Pathway

Oxidative stress injury (OSI) is an important pathological process in lung ischemia-reperfusion injury (LIRI), and diabetes mellitus (DM) can exacerbate this injury. Dexmedetomidine protects against LIRI by reducing OSI. However, the effect of dexmedetomidine on LIRI under diabetic conditions remains unclear. Therefore, this study is aimed at exploring the effects and mechanisms of dexmedetomidine on OSI induced by LIRI in diabetic rats. Rats were randomly divided into control+sham (CS), DM+sham (DS), control+ischemia-reperfusion (CIR), DM+ischemia-reperfusion (DIR), and DM+ischemia-reperfusion+dexmedetomidine (DIRD) groups ( $n=6$ ). In the CS and DS groups, the nondiabetic and diabetic rats underwent thoracotomy only without LIRI. In the CIR, DIR, and DIRD groups, LIRI was induced through left hilum occlusion for 60 min, followed by reperfusion for 120 min in nondiabetic and diabetic rats, and rats in the DIRD group were administered dexmedetomidine (3, 5, and 10 μg/kg). Compared with those in the CS group, the OSI, lung compliance, apoptosis, and oxygenation indices deteriorated in the DS group ( $P<0.05$ ), and these indices were further aggravated in the CIR and DIR groups ( $P<0.05$ ), being the worst in the DIR group ( $P<0.05$ ). Compared to those of the DIR group, the OSI, lung compliance ( $15.8\pm 2.4$ vs. $11.6\pm 1.7\text{ml}/\text{kg}$ ), apoptosis ( $22.5\pm 2.6$ vs. $51.8\pm 5.7$ ), oxygenation ( $381\pm 58$ vs. $308\pm 78\text{mmHg}$ ), and caspase-3 and caspase-9 protein expression indices were attenuated, and Nrf2 and sulfiredoxin1 protein expression was increased in the DIRD group ( $P<0.05$ ). And the lung injury, oxygenation, OSI, and Nrf2 and sulfiredoxin1 protein expression changed in a concentration-dependent manner. In conclusion, dexmedetomidine alleviated lung OSI and improved lung function in a diabetic rat LIRI model through the Nrf2-sulfiredoxin1 pathway.

NETosis in ischemic/reperfusion injuries: An organ-based review

Neutrophil extracellular trap (NETosis), the web-like structures induced by neutrophil death, is an important inflammatory mechanism of the immune system leading to reactive oxygen species production/coagulopathy, endothelial dysfunction, atherosclerosis, and ischemia. NETosis exerts its role through different mechanisms such as triggering Toll-like receptors, inflammatory cytokines, platelet aggregation, neutrophil activation/infiltration, and vascular impairment. NETosis plays a key role in the prognosis of coronary artery disease, ischemic injury of kidney, lung, gastrointestinal tract and skeletal muscles. In this review, we explored the molecular mechanisms involved in NETosis, and ischemic/reperfusion injuries in body organs.

Mangiferin inhibits hypoxia/reoxygenation-induced alveolar epithelial cell injury via the SIRT1/AMPK signaling pathway

Lung ischemia-reperfusion injury (LIRI) is one of the complications that can occur after lung transplantation and may lead to morbidity and mortality. Mangiferin (MAF) is a naturally occurring glucosyl xanthone that has been documented to possess anti-inflammatory, immunomodulatory and potent antioxidant effects. The purpose of the present study was to investigate the effect of MAF on LIRI using a hypoxia-reoxygenation (H/R) cell model. In the present study, the viability of lung alveolar epithelial cells (A549) and H/R-A549 were detected by MTT assay. ELISA was used to evaluate the expression levels of IL-6 and IL-1β. TUNEL assay and western blotting were used to evaluate the apoptosis. In addition, H/R-A549 cells were treated with sirtinol, which is known inhibitor of sirtuin 1 (SIRT1) activity, to determine the effects of MAF on proteins associated with the SIRT1/5'AMP-activate protein kinase (AMPK) signaling pathway using western blotting. The results showed that 20 µM MAF exerted a protective effect on A549 cells against H/R mediating no clear cytotoxic effects. In terms of inflammation, MAF reduced IL-6, IL-1β, cyclooxygenase-2 and inducible nitric oxide synthase expression, which was accompanied by activation of the SIRT1/AMPK signaling pathway. In addition, compared with those in the group treated with sirtinol, expression of SIRT1, Bcl-2 and AMPK activity were elevated in MAF-treated H/R-A549 cells, whereas the expression of Bax, cleaved caspase-3 and cleaved caspase-9 was suppressed. TUNEL analysis of H/R-A549 cells treated with MAF in combination with sirtinol revealed that treatment with sirtinol blocked the SIRT1/AMPK signaling pathway and increased the apoptosis rate compared with the MAF group. Taken together, results of the present study revealed that MAF could inhibit lung H/R cell injury through the SIRT1/AMPK signaling pathway.

ZFP36 protects lungs from intestinal I/R-induced injury and fibrosis through the CREBBP/p53/p21/Bax pathway

Acute lung injury induced by ischemia-reperfusion (I/R)-associated pulmonary inflammation is associated with high rates of morbidity. Despite advances in the clinical management of lung disease, molecular therapeutic options for I/R-associated lung injury are limited. Zinc finger protein 36 (ZFP36) is an AU-rich element-binding protein that is known to suppress the inflammatory response. A ZFP36 binding site occurs in the 3' UTR of the cAMP-response element-binding protein (CREB) binding protein (CREBBP) gene, which is known to interact with apoptotic proteins to promote apoptosis. In this study, we investigate the involvement of ZFP36 and CREBBP on I/R-induced lung injury in vivo and in vitro. Intestinal ischemia/reperfusion (I/R) activates inflammatory responses, resulting in injury to different organs including the lung. Lung tissues from ZFP36-knockdown mice and mouse lung epithelial (MLE)-2 cells were subjected to either Intestinal I/R or hypoxia/reperfusion, respectively, and then analyzed by Western blotting, immunohistochemistry, and real-time PCR. Silico analyses, pull down and RIP assays were used to analyze the relationship between ZFP36 and CREBBP. ZFP36 deficiency upregulated CREBBP, enhanced I/R-induced lung injury, apoptosis, and inflammation, and increased I/R-induced lung fibrosis. In silico analyses indicated that ZFP36 was a strong negative regulator of CREBBP mRNA stability. Results of pull down and RIP assays confirmed that ZFP36 direct interacted with CREBBP mRNA. Our results indicated that ZFP36 can mediate the level of inflammation-associated lung damage following I/R via interactions with the CREBBP/p53/p21/Bax pathway. The downregulation of ZFP36 increased the level of fibrosis.

Methane Inhalation Protects Against Lung Ischemia-Reperfusion Injury in Rats by Regulating Pulmonary Surfactant via the Nrf2 Pathway

Methane (CH₄) exerted protective effects against lung ischemia-reperfusion (I/R) injury, but the mechanism remains unclear, especially the role of pulmonary surfactant. Therefore, this study aimed to explore the effects of CH₄ inhalation on pulmonary surfactant in rat lung I/R injury and to elucidate the mechanism. Rats were randomly divided into three groups (n = 6): the sham, I/R control, and I/R CH₄ groups. In the sham group, only thoracotomy was performed on the rats. In the I/R control and I/R CH₄ groups, the rats underwent left hilum occlusion for 90 min, followed by reperfusion for 180 min and ventilation with O₂ or 2.5% CH₄, respectively. Compared with those of the sham group, the levels of large surfactant aggregates (LAs) in pulmonary surfactant, lung compliance, oxygenation decreased, the small surfactant aggregates (SAs), inflammatory response, oxidative stress injury, and cell apoptosis increased in the control group (P < 0.05). Compared to the control treatment, CH₄ increased LA (0.42 ± 0.06 vs. 0.31 ± 0.09 mg/kg), oxygenation (201 ± 11 vs. 151 ± 14 mmHg), and lung compliance (16.8 ± 1.0 vs. 11.5 ± 1.3 ml/kg), as well as total antioxidant capacity and Nrf2 protein expression and decreased the inflammatory response and number of apoptotic cells (P < 0.05). In conclusion, CH₄ inhalation decreased oxidative stress injury, inflammatory response, and cell apoptosis, and improved lung function through Nrf2-mediated pulmonary surfactant regulation in rat lung I/R injury.

Pirfenidone attenuates synovial fibrosis and postpones the progression of osteoarthritis by anti-fibrotic and anti-inflammatory properties in vivo and in vitro

Background

Osteoarthritis (OA) is a disease of the entire joint involving synovial fibrosis and inflammation. Pathological changes to the synovium can accelerate the progression of OA. Pirfenidone (PFD) is a potent anti-fibrotic drug with additional anti-inflammatory properties. However, the influence of PFD on OA is unknown.

Methods

Proliferation of human fibroblast-like synoviocytes (FLSs) after treatment with TGF-β1 or PFD was evaluated using a Cell Counting Kit-8 assay and their migration using a Transwell assay. The expression of fibrosis-related genes (COL1A1, TIMP-1, and ACTA-2) and those related to inflammation (IL-6 and TNF-α) was quantified by real-time quantitative PCR. The protein expression levels of COL1A1, α-SMA (coded by ACTA-2), IL-6 and TNF-α were measured by enzyme-linked immunosorbent assay. A rabbit model of OA was established and then PFD was administered by gavage. The expression of genes related to fibrosis (COL1A1, TIMP-1, and ADAM-12) and inflammation (IL-6 and TNF-α) was measured using RNA extracted from the synovium. Synovial tissue was examined histologically after staining with H&E, Masson’s trichrome, and immunofluorescence. Synovitis scores, the volume fraction of collagen, and mean fluorescence intensity were calculated. Degeneration of articular cartilage was analyzed using a Safranin O-fast green stain and OARSI grading.

Results

The proliferation of FLSs was greatest when induced with 2.5 ng/ml TGF-β1 although it did not promote their migration. Therefore, 2.5 ng/ml TGF-β1 was used to stimulate the FLSs and evaluate the effects of PFD, which inhibited the migration of FLSs at concentrations as low as 1.0 mg/ml. PFD decreased the expression of COL1A1 while TGF-β1 increased both mRNA and protein expression levels of IL-6 but had no effect on α-SMA or TNF-α expression. PFD decreased mRNA expression levels of COL1A1, IL-6, and TNF-α in vivo. H&E staining and synovitis scores indicated that PFD reduced synovial inflammation, while Masson’s trichrome and immunofluorescence staining suggested that PFD decreased synovial fibrosis. Safranin O-Fast Green staining and the OARSI scores demonstrated that PFD delayed the progression of OA.

Conclusions

PFD attenuated synovial fibrosis and inflammation, and postponed the progression of osteoarthritis in a modified Hulth model of OA in rabbits, which was related to its anti-fibrotic and anti-inflammatory properties.

Alamandine via MrgD receptor attenuates pulmonary fibrosis via NOX4 and autophagy pathway

Alamandine (ALA) and its receptor MrgD were recently identified as components of the renin-angiotensin system, which confer protection against cardio-fibrosis and renal-fibrosis; however, the effects of ALA on pulmonary fibrosis are unknown. This study was designed to serve two goals: (i) to evaluate the ALA/MrgD axis ability in the prevention of angiotensin II (Ang II) - induced pulmonary fibrosis in fibroblasts, and (ii) to determine the effect of ALA in bleomycin (BLM) - treated C57B/6 mice. In vivo experiments revealed that the treatment of C57B/6 mice with ALA prevented BLM-induced fibrosis, and these findings were similar to those reported for pirfenidone. The antifibrosis actions of ALA were mediated via alleviation of oxidative injury and autophagy induction. In addition, in vitro studies revealed that ALA treatment attenuated Ang II-induced α-collagen I, CTGF, and α-SMA production in fibroblast which was blocked by D-Pro7-Ang-(1-7), a MrgD antagonist. This led to alleviation of oxidative injury and induction of autophagy similar to that reported for rapamycin. This study demonstrated that ALA via MrgD receptor reduced pulmonary fibrosis through attenuation of oxidative injury and induction of autophagy.

Protective effect of necrosulfonamide on rat pulmonary ischemia-reperfusion injury via inhibition of necroptosis

BACKGROUND

Necroptosis plays an important role in cell death during pulmonary ischemia-reperfusion injury (IRI). We hypothesized that therapy with necrosulfonamide (NSA), a mixed-lineage kinase domain-like protein inhibitor, would attenuate lung IRI.

METHODS

Rats were assigned at random into the sham operation group (n = 6), vehicle group (n = 8), or NSA group (n = 8). In the NSA and vehicle groups, the animals were heparinized and underwent left thoracotomy, and the left hilum was clamped for 90 minutes, followed by reperfusion for 120 minutes. NSA (0.5 mg/body) and a solvent were administered i.p. in the NSA group and the vehicle group, respectively. The sham group underwent 210 minutes of perfusion without ischemia. After reperfusion, arterial blood gas analysis, physiologic data, lung wet-to-dry weight ratio, histologic changes, and cytokine levels were assessed. Fluorescence double immunostaining was performed to evaluate necroptosis and apoptosis.

RESULTS

Arterial partial pressure of oxygen/fraction of inspired oxygen (PaO₂/FiO₂) was better, dynamic compliance was higher, and mean airway pressure and lung edema were lower in the NSA group compared with the vehicle group. Moreover, in the NSA group, lung injury was significantly alleviated, and the mean number of necroptotic cells (55.3 ± 4.06 vs 78.2 ± 6.87; P = .024), but not of apoptotic cells (P = .084), was significantly reduced compared with the vehicle group. Interleukin (IL)-1β and IL-6 levels were significantly lower with NSA administration.

CONCLUSIONS

In a rat model, our results suggest that NSA may have a potential protective role in lung IRI through the inhibition of necroptosis.

Antifibrotic drugs in connective tissue disease-related interstitial lung disease (CTD-ILD): from mechanistic insights to therapeutic applications

Fibrosing interstitial lung disease (ILD) is one of the most important causes of morbidity and mortality in patients with connective tissue diseases (CTDs), which include systemic sclerosis, rheumatoid arthritis, Sjögren's syndrome, idiopathic inflammatory myositis and systemic lupus erythematosus. The treatment of CTD-ILDs is challenging due to the paucity of proven effective treatments. Recently, two antifibrotic drugs conditionally approved for use in patients with idiopathic pulmonary fibrosis, nintedanib and pirfenidone, have been trialled in CTD-ILDs based on overlapping pathological and clinical features between the two diseases. In this narrative review, we discuss the experimental evidence and clinical trials investigating the efficacy and safety of antifibrotic drugs in patients with CTD-ILDs and the potential mechanisms of action involved. Results from clinical trials suggest that nintedanib use retards lung function decline in progressive fibrotic CTD-ILDs. By contrast, the evidence for the efficacy of pirfenidone in these groups is not equally compelling. Further, well-designed randomized clinical trials are needed to evaluate the efficacy and safety of individual antifibrotic drugs in specific CTD-ILD subgroups.

The effects of pirfenidone on ischaemia-reperfusion injury in testicular torsion-induced rat model

The aim of this study was to analyse the effect of pirfenidone against ischaemia-reperfusion injury occurring after detorsion in rats with induced testicular torsion model. Group 1 was assigned as the control group. Group 2 first had testis torsion performed, and then, testicular detorsion was performed. Group 3 had similar procedures to the rats in Group 2. Rats in Group 3 additionally had 325 mg/kg pirfenidone administered immediately after ischaemia. The blood samples were analysed spectrophotometrically. To determine the intensity of tissue injury, haemorrhage, oedema and congestion levels were evaluated with direct microscopic investigation of testis. Seminiferous tubule architecture, spermatogenesis processes and germ cell maturation were graded by Johnsen and Cosentino scoring systems. In Group 3, superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities increased compared with Group 2 (p:.03 and p:.049 respectively). Additionally, the mean malondialdehyde (MDA) value was higher in Group 2 compared with the other groups (p:.001). Histopathological investigation of rats in Group 3 identified positive changes in haemorrhage, oedema and congestion levels compared with Group 2 (p:.031, p:.048, p:.044 respectively). Similarly, Johnsen and Cosentino scores were positively affected in Group 3 (p:.033, p:.032 respectively). Pirfenidone is protective against testicular oxidative damage.

Pirfenidone: Molecular Mechanisms and Potential Clinical Applications in Lung Disease

Pirfenidone (PFD) is a pharmacological compound with therapeutic efficacy in idiopathic pulmonary fibrosis. It has been chiefly characterized as an antifibrotic agent, although it was initially developed as an antiinflammatory compound because of its ability to diminish the accumulation of inflammatory cells and cytokines. Despite recent studies that have elucidated key mechanisms, the precise molecular activities of PFD remain incompletely understood. PFD modulates fibrogenic growth factors, thereby attenuating fibroblast proliferation, myofibroblast differentiation, collagen and fibronectin synthesis, and deposition of extracellular matrix. This effect is mediated by suppression of TGF-β1 (transforming growth factor-β1) and other growth factors. Here, we appraise the impact of PFD on TGF-β1 production and its downstream pathways. Accumulating evidence indicates that PFD also downregulates inflammatory pathways and therefore has considerable potential as a viable and innovative antiinflammatory compound. We examine the effects of PFD on inflammatory cells and the production of pro- and antiinflammatory cytokines in the lung. In this context, recent evidence that PFD can target inflammasome pathways and ensuing lung inflammation is highlighted. Finally, the antioxidant properties of PFD, such as its ability to inhibit redox reactions and regulate oxidative stress-related genes and enzymes, are detailed. In summary, this narrative review examines molecular mechanisms underpinning PFD and its recognized benefits in lung fibrosis. We highlight preclinical data that demonstrate the potential of PFD as a nonsteroidal antiinflammatory agent and outline areas for future research.

Protective Effects of a Hydrogen-Rich Preservation Solution in a Canine Lung Transplantation Model

BACKGROUND

Molecular hydrogen (H₂) has protective effects against ischemia-reperfusion injury in various organs. Because they are easier to transport and safer to use than inhaled H₂, H₂-rich solutions are suitable for organ preservation. In this study, we examined the protective effects of an H₂-rich solution for lung preservation in a canine left lung transplantation (LTx) model.

METHODS

Ten beagles underwent orthotopic left LTx after 23 hours of cold ischemia followed by reperfusion for 4 hours. Forty-five minutes after reperfusion, the right main pulmonary artery was clamped to evaluate the function of the implanted graft. The beagles were divided into two groups: control group (n = 5), and H₂ group (n = 5). In the control group, the donor lungs were flushed and immersed during cold preservation at 4°C using ET-Kyoto solution, and in the H₂ group, these were flushed and immersed using H₂-rich ET-Kyoto solution. Physiologic assessments were performed during reperfusion. After reperfusion, the wet-to-dry ratios were determined, and histology examinations were performed.

RESULTS

Significantly higher partial pressure of arterial oxygen and significantly lower partial pressure of carbon dioxide were observed in the H₂ group than in the control group (P = .045 and P < .001, respectively). The wet-to-dry ratio was significantly lower in the H₂ group than in the control group (P = .032). Moreover, in histology examination, less lung injury and fewer apoptotic cells were observed in the H₂ group (P < .001 and P < .001, respectively).

CONCLUSIONS

Our results demonstrated that the H₂-rich preservation solution attenuated ischemia-reperfusion injury in a canine left LTx model.

Methane attenuates lung ischemia-reperfusion injury via regulating PI3K-AKT-NFκB signaling pathway

Objective: This study aims to investigate the protective effects and possible mechanism of methane-rich saline (MS) on lung ischemia-reperfusion injury (LIRI) in rats.Methods: MS (2 ml/kg and 20 ml/kg) was injected intraperitoneally in rats after LIRI. Lung injury was assayed by Hematoxylin-eosin (HE) staining and wet-to-dry weight (W/D). The cells in the bronchoalveolar lavage fluid (BALF) and blood were counted. Oxidative stress was examined by the level of malondialdehyde (MDA) and superoxide dismutase (SOD). Inflammatory factors including tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-10 (IL-10) were determined by ELISA. Lung tissue apoptosis was detected by TUNEL staining and western blotting of Bcl-2, Bax, and caspase-3. The expressions of IкBα, p38, PI3K, AKT, and NF-κB were analyzed with Western blotting.Results: MS effectively decreased the lung W/D ratio as well as the lung pathological damage and reduced the localized infiltration of inflammatory cells. Methane suppressed the expression of the PI3K-AKT-NFκB signaling pathway during the lung IR injury, which inhibited the activation of NF-kB and decreased the level of inflammatory cytokines, such as TNF-α, IL-1β, and IL-10. Moreover, we found that MS treatment relieved reactive oxygen species (ROS) damage by downregulating MDA and upregulating SOD. MS treatment also regulated apoptosis-related proteins, such as Bcl-2, Bax, and caspase-3.Conclusions: MS could repair LIRI and reduce the release of oxidative stress, inflammatory cytokines, and cell apoptosis via the PI3K-AKT-NFκB signaling pathway, which may provide a novel and promising strategy for the treatment of LIRI.