Autophagy induced by DAMPs facilitates the inflammation response in lungs undergoing ischemia-reperfusion injury through promoting TRAF6 ubiquitination

Salidroside inhibits the ferroptosis to alleviate lung ischemia reperfusion injury via the JAK2/STAT3 signalling pathway

OBJECTIVE

The present study aims to investigate the protective potential of salidroside in both lung ischemia/reperfusion injury (LIRI) mice model and cell hypoxia/reoxygenation (H/R)model and the involvement of ferroptosis and JAK2/STAT3 pathway.

MATERIALS AND METHODS

After we established the IR-induced lung injury model in mice, we administered salidroside and the ferroptosis inhibitor, ferrostatin-1, then assessed the lung tissue injury, ferroptosis (levels of reactive oxygen species level, malondialdehyde and glutathione), and inflammation in lung tissues. The levels of ferroptosis-related proteins (glutathione peroxidase 4, fibroblast-specific protein 1, solute carrier family 1 member 5 and glutaminase 2) in the lung tissue were measured with Western blotting. Next, BEAS-2B cells were used to establish an H/R cell model and treated with salidroside or ferrostatin-1 before the cell viability and the levels of lactate dehydrogenase (LDH), inflammatory factor, ferroptosis-related proteins were measured. The activation of the JAK2/STAT3 signaling pathway was measured with Western blotting, then its role was confirmed with STAT3 knockdown.

RESULTS

Remarkably, salidroside was found to alleviate ferroptosis, inflammation, and lung injury in LIRI mice and the cell injury in H/R cell model. Severe ferroptosis were observed in LIRI mice models and H/R-induced BEAS-2B cells, which was alleviated by salidroside. Furthermore, salidroside could inhibit JAK2/STAT3 activation induced by LIRI. STAT3 knockdown could enhance the effect of salidroside treatment on H/R-induced cell damage and ferroptosis in vitro.

CONCLUSIONS

Salidroside inhibits ferroptosis to alleviate lung ischemia reperfusion injury via the JAK2/STAT3 signaling pathway.

Impact of Pre-Transplant Left Ventricular Diastolic Pressure on Primary Graft Dysfunction after Lung Transplantation: A Narrative Review

Lung transplantation (LT) constitutes the last therapeutic option for selected patients with end-stage respiratory disease. Primary graft dysfunction (PGD) is a form of severe lung injury, occurring in the first 72 h following LT and constitutes the most common cause of early death after LT. The presence of pulmonary hypertension (PH) has been reported to favor PGD development, with a negative impact on patients' outcomes while complicating medical management. Although several studies have suggested a potential association between pre-LT left ventricular diastolic dysfunction (LVDD) and PGD occurrence, the underlying mechanisms of such an association remain elusive. Importantly, the heterogeneity of the study protocols and the various inclusion criteria used to define the diastolic dysfunction in those patients prevents solid conclusions from being drawn. In this review, we aim at summarizing PGD mechanisms, risk factors, and diagnostic criteria, with a further focus on the interplay between LVDD and PGD development. Finally, we explore the predictive value of several diastolic dysfunction diagnostic parameters to predict PGD occurrence and severity.

African swine fever virus A137R protein inhibits NF-κB activation via suppression of MyD88 signaling in PK15 and 3D4/21 cells in vitro

African swine fever (ASF) is an infectious disease with high mortality caused by African swine fever virus (ASFV), which poses a great threat to the global swine industry. ASFV has evolved multiple strategies to evade host antiviral innate immunity by perturbing inflammatory responses and interferon production. However, the molecular mechanisms underlying manipulation of inflammatory responses by ASFV proteins are not fully understood. Here, we report that A137R protein of ASFV is a key suppressor of host inflammatory responses. Ectopic expression of ASFV A137R in HEK293T cells significantly inhibited the activation of IL-8 and NF-κB promoters triggered by Sendai virus (SeV), influenza A virus (IAV), or vesicular stomatitis virus (VSV). Accordingly, forced A137R expression caused a significant decrease in the production of several inflammatory cytokines such as IL-8, IL-6 and TNF-α in the cells infected with SeV or IAV. Similar results were obtained from experiments using A137R overexpressing PK15 and 3D4/21 cells infected with SeV or VSV. Furthermore, we observed that A137R impaired the activation of MAPK and NF-κB signaling pathways, as enhanced expression of A137R significantly decreased the phosphorylation of JNK, p38 and p65 respectively upon viral infection (SeV or IAV) and IL-1β treatment. Mechanistically, we found that A137R interacted with MyD88, and dampened MyD88-mediated activation of MAPK and NF-κB signaling. Together, these findings uncover a critical role of A137R in restraining host inflammatory responses, and improve our understanding of complicated mechanisms whereby ASFV evades innate immunity.

TRAF6 triggers Mycobacterium-infected host autophagy through Rab7 ubiquitination

Tumor necrosis factor receptor-associated factor 6 (TRAF6) is an E3 ubiquitin ligase that is extensively involved in the autophagy process by interacting with diverse autophagy initiation and autophagosome maturation molecules. However, whether TRAF6 interacts with lysosomal proteins to regulate Mycobacterium-induced autophagy has not been completely characterized. Herein, the present study showed that TRAF6 interacted with lysosomal key proteins Rab7 through RING domain which caused Rab7 ubiquitination and subsequently ubiquitinated Rab7 binds to STX17 (syntaxin 17, a SNARE protein that is essential for mature autophagosome), and thus promoted the fusion of autophagosomes and lysosomes. Furthermore, TRAF6 enhanced the initiation and formation of autophagosomes in Mycobacterium-induced autophagy in both BMDMs and RAW264.7 cells, as evidenced by autophagic flux, colocalization of LC3 and BCG, autophagy rates, and autophagy-associated protein expression. Noteworthy to mention, TRAF6 deficiency exacerbated lung injury and promoted BCG survival. Taken together, these results identify novel molecular and cellular mechanisms by which TRAF6 positively regulates Mycobacterium-induced autophagy.

Therapeutic benefits of nitric oxide in lung transplantation

Lung transplantation is an evolutionary procedure from its experimental origin in the twentieth century and is now recognized as an established and routine life-saving intervention for a variety of end-stage pulmonary diseases refractory to medical management. Despite the success and continuous refinement in lung transplantation techniques, the widespread application of this important life-saving intervention is severely hampered by poor allograft quality offered from donors-after-brain-death. This has necessitated the use of lung allografts from donors-after-cardiac-death (DCD) as an additional source to expand the pool of donor lungs. Remarkably, the lung exhibits unique properties that may make it ideally suitable for DCD lung transplantation. However, primary graft dysfunction (PGD), allograft rejection and other post-transplant complications arising from unavoidable ischemia-reperfusion injury (IRI) of transplanted lungs, increase morbidity and mortality of lung transplant recipients annually. In the light of this, nitric oxide (NO), a selective pulmonary vasodilator, has been identified as a suitable agent that attenuates lung IRI and prevents PGD when administered directly to lung donors prior to donor lung procurement, or to recipients during and after transplantation, or administered indirectly by supplementing lung preservation solutions. This review presents a historical account of clinical lung transplantation and discusses the lung as an ideal organ for DCD. Next, the author highlights IRI and its clinical effects in lung transplantation. Finally, the author discusses preservation solutions suitable for lung transplantation, and the protective effects and mechanisms of NO in experimental and clinical lung transplantation.

VEGFC ameliorates salt-sensitive hypertension and hypertensive nephropathy by inhibiting NLRP3 inflammasome via activating VEGFR3-AMPK dependent autophagy pathway

Salt-sensitivity hypertension (SSHTN) is an independent predictor for cardiovascular mortality. VEGFC has been reported to be a protective role in SSHTN and hypertensive kidney injury. However, the underlying mechanisms remain largely unclear. The current study aimed to explore the protective effects and mechanisms of VEGFC against SSHTN and hypertensive nephropathy. Here, we reported that VEGFC attenuated high blood pressure as well as protected against renal inflammation and fibrosis in SSHTN mice. Moreover, VEGFC suppressed the activation of renal NLRP3 inflammasome in SSHTN mice. In vitro, we found VEGFC inhibited NLRP3 inflammasome activation, meanwhile, upregulated autophagy in high-salt-induced macrophages, while these effects were reversed by an autophagy inhibitor 3MA. Furthermore, in vivo, 3MA pretreatment weakened the protective effects of VEGFC on SSHTN and hypertensive nephropathy. Mechanistically, VEGF receptor 3 (VEGFR3) kinase domain activated AMPK by promoting the phosphorylation at Thr183 via binding to AMPK, thus enhancing autophagy activity in the context of high-salt-induced macrophages. These findings indicated that VEGFC inhibited NLRP3 inflammasome activation by promoting VEGFR3-AMPK-dependent autophagy pathway in high-salt-induced macrophages, which provided a mechanistic basis for the therapeutic target in SSHTN and hypertensive kidney injury.

The interaction between autophagy, Helicobacter pylori, and gut microbiota in gastric carcinogenesis

Chronic infection with Helicobacter pylori is the primary risk factor for the development of gastric cancer. Hindering our ability to comprehend the precise role of autophagy during H. pylori infection is the complexity of context-dependent autophagy signaling pathways. Recent and ongoing progress in understanding H. pylori virulence allows new frontiers of research for the crosstalk between autophagy and H. pylori. Novel approaches toward discovering autophagy signaling networks have further revealed their critical influence on the structure of gut microbiota and the metabolome. Here we intend to present a holistic view of the perplexing role of autophagy in H. pylori pathogenesis and carcinogenesis. We also discuss the intermediate role of autophagy in H. pylori-mediated modification of gut inflammatory responses and microbiota structure.

Primary Graft Dysfunction in Lung Transplantation: A Review of Mechanisms and Future Applications

Lung allograft recipients have worse survival than all other solid organ transplant recipients, largely because of primary graft dysfunction (PGD), a major form of acute lung injury affecting a third of lung recipients within the first 72 h after transplant. PGD is the clinical manifestation of ischemia-reperfusion injury and represents the predominate cause of early morbidity and mortality. Despite PGD's impact on lung transplant outcomes, no targeted therapies are currently available; hence, care remains supportive and largely ineffective. This review focuses on molecular and innate immune mechanisms of ischemia-reperfusion injury leading to PGD. We also discuss novel research aimed at discovering biomarkers that could better predict PGD and potential targeted interventions that may improve outcomes in lung transplantation.

PIF1 Promotes Autophagy to Inhibit Chronic Hypoxia Induced Apoptosis of Pulmonary Artery Endothelial Cells

Purpose

Pulmonary artery hypertension (PAH) is a common complication of chronic obstructive pulmonary disease and obstructive sleep apnea/hypopnea syndrome worldwide. Pulmonary vascular alterations associated with PAH have multifactorial causes, in which endothelial cells play an important role. Autophagy is closely related to endothelial cell injury and the development of PAH. PIF1 is a multifunctional helicase crucial for cell survival. The present study investigated the effect of PIF1 on autophagy and apoptosis in human pulmonary artery endothelial cells (HPAECs) under chronic hypoxia stress.

Methods

Chronic hypoxia Gene expression profiling chip-assays identified the PIF1 gene as differentially expressed, which was verified by RT-qPCR analysis. Electron microscopy, immunofluorescence, and Western blotting were used to analyze autophagy and the expression of LC3 and P62. Apoptosis was analyzed using flow cytometry.

Results

Our study found that chronic hypoxia induces autophagy in HPAECs, and apoptosis was exacerbated by inhibiting autophagy. Levels of the DNA helicase PIF1 were increased in HPAECs after chronic hypoxia. PIF1 knockdown inhibited autophagy and promoted the apoptosis of HPAECs under chronic hypoxia stress.

Conclusion

Based on these findings, we conclude that PIF1 inhibits the apoptosis of HPAECs by accelerating the autophagy pathway. Therefore, PIF1 plays a crucial role in HPAEC dysfunction in chronic hypoxia-induced PAH and may be a potential target for the treatment of PAH.

FGF10 ameliorates lipopolysaccharide-induced acute lung injury in mice via the BMP4-autophagy pathway

Introduction: Damage to alveolar epithelial cells caused by uncontrolled inflammation is considered to be the main pathophysiological change in acute lung injury. FGF10 plays an important role as a fibroblast growth factor in lung development and lung diseases, but its protective effect against acute lung injury is unclear. Therefore, this study aimed to investigate protective effect and mechanism of FGF10 on acute lung injury in mice. Methods: ALI was induced by intratracheal injection of LPS into 57BL/6J mice. Six hours later, lung bronchoalveolar lavage fluid (BALF) was acquired to analyse cells, protein and the determination of pro-inflammatory factor levels, and lung issues were collected for histologic examination and wet/dry (W/D) weight ratio analysis and blot analysis of protein expression. Results: We found that FGF10 can prevent the release of IL-6, TNF-α, and IL-1β, increase the expression of BMP4 and autophagy pathway, promote the regeneration of alveolar epithelial type Ⅱ cells, and improve acute lung injury. BMP4 gene knockdown decreased the protective effect of FGF10 on the lung tissue of mice. However, the activation of autophagy was reduced after BMP4 inhibition by Noggin. Additionally, the inhibition of autophagy by 3-MA also lowered the protective effect of FGF10 on alveolar epithelial cells induced by LPS. Conclusions: These data suggest that the protective effect of FGF10 is related to the activation of autophagy and regeneration of alveolar epithelial cells in an LPS-induced ALI model, and that the activation of autophagy may depend on the increase in BMP4 expression.

Dexmedetomidine attenuates subarachnoid hemorrhage-induced acute lung injury through regulating autophagy and TLR/NFκB signaling pathway

BACKGROUND

Acute lung injury (ALI) is the most serious complication of subarachnoid hemorrhage (SAH). We investigated role of autophagy and inflammatory signaling pathways in lung damage and therapeutic effects of dexmedetomidine (DEX).

METHODS

Fifty male Wistar rats were randomly divided into five groups: sham, SAH, SAH+ DEX5, SAH+DEX25, and SAH+DEX50. SAH was induced using endovascular perforation technique. All rats received mechanical ventilation for 60 minutes. At 2 and 24 h of SAH induction, SAH+DEX groups were treated with 5, 25, and 50 µg/kg of DEX, respectively. Histological ALI score and pulmonary edema were assessed after 48 h. Lung expression of LC3B, ATG3, p62, TLR4, TLR9, and NFκB was assessed using western blotting and quantitative PCR. Blood levels of IL-6, IL-1β, IFN-γ, and TNFα were also assessed.

RESULTS

SAH induced ALI and pulmonary edema, which were attenuated in SAH+DEX5 (P < 0.001 for both) and SAH+DEX25 groups (P = 0.001 and P < 0.001 for ALI and edema, respectively). Lung expressions of LC3B and ATG3 were upregulated in SAH group, which was attenuated in SAH+DEX5 and SAH+DEX25 groups. Lung expressions of TLR4, TLR9, and NFκB were increased in SAH group, which was attenuated in SAH+DEX5 group. Blood IL-6 level was increased in SAH group and attenuated in SAH+DEX5 and SAH+DEX25 groups. Blood IFN-γ level was lower in SAH group than in sham group, and it was increased in SAH+DEX25 group.

CONCLUSIONS

Low-dose DEX treatment after SAH may protect against ALI by disrupting pathological brain-lung crosstalk and alleviating autophagy flux and TLR-dependent inflammatory pathways.

Adiponectin protects skeletal muscle from ischaemia–reperfusion injury in mice through miR ‐21/ PI3K /Akt signalling pathway

Previous studies have confirmed that adiponectin (APN) plays a protective role in myocardial ischaemia-reperfusion (IR) injury, and the aim of this study was to investigate its effect on skeletal muscle. ELISA was used to detect the levels of Creatinine Kinase (CK), LDH, SOD and MDA in the plasma of the lower limbs of mice, and the levels of IL-6, IL-1β and TNF-α in the gastrocnemius. Quantitative PCR was used to detect the expression level of miR-21. TUNEL staining was used to detect the apoptosis of the gastrocnemius. The expression levels of apoptosis proteins, autophagy marker proteins and downstream target genes of miR-21 in gastrocnemius were detected by Western Blot. The results of this study revealed that APN levels were significantly reduced in gastrocnemius of IR mice. The oxidative stress, inflammatory response, apoptosis and autophagy induced by IR were significantly ameliorated by APN injection. The above effects of APN may be achieved through miR-21/PI3K signalling pathway, as found by interfering gene expression levels with miRNA antagomir and lentiviral injection. Taken together, our study revealed that APN protects skeletal muscle from IR injury through miR-21 /PI3K/Akt signalling pathway through inhibiting inflammatory response, apoptosis and autophagy.

Classic and Current Opinions in Human Organ and Tissue Transplantation

Graft tolerance is a pathophysiological condition heavily reliant on the dynamic interaction of the innate and adaptive immune systems. Genetic polymorphism determines immune responses to tissue/organ transplantation, and intricate humoral and cell-mediated mechanisms control these responses. In transplantation, the clinician's goal is to achieve a delicate equilibrium between the allogeneic immune response, undesired effects of the immunosuppressive drugs, and the existing morbidities that are potentially life-threatening. Transplant immunopathology involves sensitization, effector, and apoptosis phases which recruit and engages immunological cells like natural killer cells, lymphocytes, neutrophils, and monocytes. Similarly, these cells are involved in the transfer of normal or genetically engineered T cells. Advances in tissue transplantation would involve a profound knowledge of the molecular mechanisms that underpin the respective immunopathology involved and the design of precision medicines that are safe and effective.

Progress in preclinical studies of macrophage autophagy in the regulation of ALI/ARDS

Acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) is a critical clinical syndrome with high morbidity and mortality that poses a major challenge in critical care medicine. The development of ALI/ARDS involves excessive inflammatory response, and macrophage autophagy plays an important role in regulating the inflammatory response in ALI/ARDS. In this paper, we review the effects of autophagy in regulating macrophage function, discuss the roles of macrophage autophagy in ALI/ARDS, and highlight drugs and other interventions that can modulate macrophage autophagy in ALI/ARDS to improve the understanding of the mechanism of macrophage autophagy in ALI/ARDS and provide new ideas and further research directions for the treatment of ALI/ARDS.

The Chemokines CXC, CC and C in the Pathogenesis of COVID-19 Disease and as Surrogates of Vaccine-Induced Innate and Adaptive Protective Responses

COVID-19 is one of the progressive viral pandemics that originated from East Asia. COVID-19 or SARS-CoV-2 has been shown to be associated with a chain of physio-pathological mechanisms that are basically immunological in nature. In addition, chemokines have been proposed as a subgroup of chemotactic cytokines with different activities ranging from leukocyte recruitment to injury sites, irritation, and inflammation to angiostasis and angiogenesis. Therefore, researchers have categorized the chemotactic elements into four classes, including CX3C, CXC, CC, and C, based on the location of the cysteine motifs in their structures. Considering the severe cases of COVID-19, the hyperproduction of particular chemokines occurring in lung tissue as well as pro-inflammatory cytokines significantly worsen the disease prognosis. According to the studies conducted in the field documenting the changing expression of CXC and CC chemokines in COVID-19 cases, the CC and CXC chemokines contribute to this pandemic, and their impact could reflect the development of reasonable strategies for COVID-19 management. The CC and the CXC families of chemokines are important in host immunity to viral infections and along with other biomarkers can serve as the surrogates of vaccine-induced innate and adaptive protective responses, facilitating the improvement of vaccine efficacy. Furthermore, the immunogenicity elicited by the chemokine response to adenovirus vector vaccines may constitute the basis of vaccine-induced immune thrombotic thrombocytopaenia.

Oleuropein ameliorated lung ischemia-reperfusion injury by inhibiting TLR4 signaling cascade in alveolar macrophages

Lung ischemia-reperfusion (I/R) injury is a common postoperative complication in patients with lung transplantation, pulmonary embolism, and cardiopulmonary bypass. Lung I/R injury is a sterile inflammatory process that leads to lung dysfunction, and is an important cause of patient death. Effectively alleviating lung I/R injury can thus improve the prognosis of patients. In this study, we created a mouse model of lung I/R injury by transient unilateral left pulmonary artery occlusion. 6-8 weeks male C57BL/6 mice were randomly assigned to four groups: Sham, I/R, I/R + oleuropein (OLE) and OLE. OLE (50 mg/kg) was orally 24 h and 30 min before anesthesia. Measurement of lung pathohistological, isolated alveolar macrophages (AMs), inflammatory mediators, TLR4 and its downstream factors (MyD88, NF-κB) were performed. We then evaluated the ability of oleuropein (OLE) to ameliorate I/R-induced lung injury and explored the possible molecular mechanisms. OLE ameliorated I/R-induced lung injury and edema and decreased inflammatory factors in lung tissue and bronchoalveolar lavage fluid. This protection required toll-like receptor 4 (TLR4). OLE significantly inhibited I/R-induced expression of TLR4 and its downstream factors in lung tissue and alveolar macrophages. In addition, hypoxia-inducible factor 1α protein accumulated in TLR4-mediated lung I/R injury, and further induced the production of inflammatory factors. Collectively, these data suggest that OLE ameliorates I/R-induced lung injury. The mechanism responsible for its protective effect may involve inhibition of the I/R-induced inflammatory response by downregulating the TLR4 signaling cascade in AMs.

The Role of Neutrophils as a Driver in Hepatic Ischemia-Reperfusion Injury and Cancer Growth

The innate immune system plays an essential role in the response to sterile inflammation and its association with liver ischemia and reperfusion injury (IRI). Liver IRI often manifests during times of surgical stress such as cancer surgery or liver transplantation. Following the initiation of liver IRI, stressed hepatocytes release damage-associated molecular patterns (DAMPs) which promote the infiltration of innate immune cells which then initiate an inflammatory cascade and cytokine storm. Upon reperfusion, neutrophils are among the first cells that infiltrate the liver. Within the liver, neutrophils play an important role in fueling tissue damage and tumor progression by promoting the metastatic cascade through the formation of Neutrophil Extracellular Traps (NETs). NETs are composed of web-like DNA structures containing proteins that are released in response to inflammatory stimuli in the environment. Additionally, NETs can aid in mediating liver IRI, promoting tumor progression, and most recently, in mediating early graft rejection in liver transplantation. In this review we aim to summarize the current knowledge of innate immune cells, with a focus on neutrophils, and their role in mediating IRI in mouse and human diseases, including cancer and transplantation. Moreover, we will investigate the interaction of Neutrophils with varying subtypes of other cells. Furthermore, we will discuss the role and different treatment modalities in targeting Neutrophils and NETs to prevent IRI.

KIF2A decreases IL-33 production and attenuates allergic asthmatic inflammation

Background

The microtubule-dependent molecular motor protein Kinesin Family Member 2A (KIF2A) is down-regulated in asthmatic human airway epithelium. However, little is known about the roles of KIF2A as well as the possible underlying mechanisms in asthma.

Methods

House dust mite (HDM) extract was administered to establish a murine model of asthma. The expression of KIF2A, IL-33 and the autophagy pathways were detected. The plasmid pCMV-KIF2A was used to overexpress KIF2A in the airway epithelial cells in vitro and in vivo. IL-4, IL-5, IL-33 and other cytokines in bronchoalveolar lavage fluid (BALF) and lung tissues homogenates were measured.

Results

In response to the challenge of house dust mite (HDM) in vitro and in vivo, airway epithelial cells displayed decreased production of KIF2A. Meanwhile, autophagy and IL-33 were increased in HMD-treated epithelial cells. Mechanistically, KIF2A decreased autophagy via suppressing mTORC1 pathway in HDM-treated epithelial cells, which contributed to the reduced production of IL-33. Moreover, in vivo KIF2A transfection reduced IL-33 and autophagy in the lung, leading to the attenuation of allergic asthma.

Conclusion

KIF2A suppressed mTORC1-mediated autophagy and decreased the production of epithelial-derived cytokine IL-33 in allergic airway inflammation. These data indicate that KIF2A may be a novel target in allergic asthma.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13223-022-00697-9.

Toll-like receptors and damage-associated molecular patterns in the pathogenesis of heart transplant rejection

Significant strides have been made in our understanding of the immune system and its role in cardiac transplant rejection. Despite the growing knowledge of immune responses, the mortality rate following cardiac transplantation remains grim. Related to procedural and pathological complications, toll-like receptor (TLR) and damage-associated molecular pattern (DAMP) signaling is the most direct and earliest interface between tissue integration and the innate immune response. This in turn can activate an adaptive immune response that further damages myocardial tissue. Furthermore, relevant literature on the status of DAMPs in the context of heart-transplantation remains limited, warranting further attention in clinical and translational research. This review aims to critically appraise the perspectives, advances, and challenges on DAMP-mediated innate immune response in the immune-mediated rejection of cardiac transplantation. Detailed analysis of the influence of TLR and DAMP signaling in mounting the immune response against the transplanted heart holds promise for improving outcomes through early detection and prevention of varied forms of organ rejection.

HMGB1: A Potential Target of Nervus Vagus Stimulation in Pediatric SARS-CoV-2-Induced ALI/ARDS

From the start of pandemics, children were described as the ones who were less affected by SARS-Cov-2 or COVID-19, which was mild in most of the cases. However, with the growing vaccination rate of the adult population, children became more exposed to the virus and more cases of severe SARS-CoV-2-induced ARDS are being diagnosed with the disabling consequences or lethal outcomes associated with the cytokine storm. Thus, we do hypothesize that some of the children could benefit from nervus vagus stimulation during COVID-19 ARDS through the inhibition of HMGB1 release and interaction with the receptor, resulting in decreased neutrophil accumulation, oxidative stress, and coagulopathy as well as lung vascular permeability. Moreover, stimulation through alpha-7 nicotinic acetylcholine receptors could boost macrophage phagocytosis and increase the clearance of DAMPs and PAMPs. Further rise of FGF10 could contribute to lung stem cell proliferation and potential regeneration of the injured lung. However, this stimulation should be very specific, timely, and of proper duration, as it could lead to such adverse effects as increased viral spread and systemic infection, especially in small children or infants due to specific pediatric immunity state and anatomical features of the respiratory system.

Autophagy-Inflammation Interplay During Infection: Balancing Pathogen Clearance and Host Inflammation

Inflammation is an essential immune response of the host against infections but is often over-activated, leading to a variety of disorders. Autophagy, a conserved degradation pathway, also protects cells by capturing intracellular pathogens that enter the cell and transporting them to the lysosome for clearance. Dysfunctional autophagy is often associated with uncontrolled inflammatory responses during infection. In recent years, more and more research has focused on the crosstalk between autophagy and inflammation. In this paper, we review the latest research advances in this field, hoping to gain insight into the mechanisms by which the body balances autophagy and inflammation in infections and how this mechanism can be used to fight infections better.

Postconditioning with Irisin Attenuates Lung Ischemia/Reperfusion Injury by Suppressing Ferroptosis via Induction of the Nrf2/HO-1 Signal Axis

Iron-dependent lipid peroxidation causes ferroptosis. This study was aimed at verifying that irisin postconditioning can inhibit ferroptosis and minimize lung ischemia/reperfusion (I/R) damage via activating the Nrf2/HO-1 signal axis. We constructed a murine model of I/R lung damage. At the onset of reperfusion, irisin, ferroptosis inhibitor ferrostatin-1, and ferroptosis inducer Fe-citrate were all administered. We discovered that irisin could reduce lung I/R injury, consistent with ferrostatin-1's action. Furthermore, irisin suppressed ferroptosis in lung I/R damage, as evidenced by lower ROS, MDA, and Fe²⁺, as well as alterations in critical protein expression (GPX4 and ACSL4). However, Fe-citrate abolished the protective effects of irisin. Transcriptome research found that irisin increased the mRNA levels of Nrf2 and HO-1. Thus, we used siRNA to investigate the role of the Nrf2/HO-1 axis in irisin-mediated protection against hypoxia/reoxygenation (H/R) damage in MLE-12 cells. Irisin consistently reduced ferroptosis and improved mitochondrial dysfunction caused by H/R. Irisin's cytoprotective function was eliminated when Nrf2 was silenced. As a result, irisin postconditioning may protect against lung I/R damage by suppressing ferroptosis via the Nrf2/HO-1 signaling axis.

Significance of Immune Status of SARS-CoV-2 Infected Patients in Determining the Efficacy of Therapeutic Interventions

Coronavirus disease 2019 (COVID-19) is now being investigated for its distinctive patterns in the course of disease development which can be indicated with miscellaneous immune responses in infected individuals. Besides this series of investigations on the pathophysiology of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), significant fundamental immunological and physiological processes are indispensable to address clinical markers of COVID-19 disease and essential to identify or design effective therapeutics. Recent developments in the literature suggest that deficiency of type I interferon (IFN) in serum samples can be used to represent a severe progression of COVID-19 disease and can be used as the basis to develop combined immunotherapeutic strategies. Precise control over inflammatory response is a significant aspect of targeting viral infections. This account presents a brief review of the pathophysiological characteristics of the SARS-CoV-2 virus and the understanding of the immune status of infected patients. We further discuss the immune system’s interaction with the SARS-CoV-2 virus and their subsequent involvement of dysfunctional immune responses during the progression of the disease. Finally, we highlight some of the implications of the different approaches applicable in developing promising therapeutic interventions that redirect immunoregulation and viral infection.

The dynamic changes in autophagy activity and its role in lung injury after deep hypothermic circulatory arrest

Deep hypothermic circulatory arrest (DHCA) can cause acute lung injury (ALI), and its pathogenesis mimics ischaemia/reperfusion (I/R) injury. Autophagy is also involved in lung I/R injury. The present study aimed to elucidate whether DHCA induces natural autophagy activation and its role in DHCA‐mediated lung injury. Here, rats were randomly assigned to the Sham or DHCA group. The sham group (n = 5) only received anaesthesia and air intubation. DHCA group rats underwent cardiopulmonary bypass (CPB) followed by the DHCA procedure. The rats were then sacrificed at 3, 6 and 24 h after the DHCA procedure (n = 5) to measure lung injury and autophagy activity. Chloroquine (CQ) was delivered to evaluate autophagic flux. DHCA caused lung injury, which was prominent 3–6 h after DHCA, as confirmed by histological examination and inflammatory cytokine quantification. Lung injury subsided at 24 h. Autophagy was suppressed 3 h but was exaggerated at 6 h. At both time points, autophagic flux appeared uninterrupted. To further assess the role of autophagy in DHCA‐mediated lung injury, the autophagy inducer rapamycin and its inhibitor 3‐methyladenine (3‐MA) were applied, and lung injury was reassessed. When rapamycin was administered at an early time point, lung injury worsened, whereas administration of 3‐MA at a late time point ameliorated lung injury, indicating that autophagy contributed to lung injury after DHCA. Our study presents a time course of lung injury following DHCA. Autophagy showed adaptive yet protective suppression 3 h after DHCA, as induction of autophagy caused worsening of lung tissue. In contrast, autophagy was exaggerated 6 h after DHCA, and autophagy inhibition attenuated DHCA‐mediated lung injury.

Heme Oxygenase-1/High Mobility Group Box 1 Pathway May Have a Possible Role in COVID-19 ARDS (Acute Respiratory Distress Syndrome): A Pilot Histological Study

COVID-19 is a pandemic disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The persistent and excessive inflammatory response can build up a clinical picture that is difficult to manage and potentially fatal. Potent activators of inflammatory phenomena are damage-associated molecular patterns (DAMPs) and, in particular, the high-mobility group box 1 (HMGB1). HMGB1 is an intranuclear protein that is either passively released during hypoxia-related necrosis or actively released by macrophages. Heme oxygenase (HO-1) has an anti-inflammatory effect by inhibiting HMGB1, which could be a therapeutic target to reduce COVID-19 inflammation. In our study, we evaluated CD3, CD4, CD8, HMGB1 and HO-1 in the COVID-19 lung and correlated it to clinical data.

FBXO22 Promotes Growth and Metastasis and Inhibits Autophagy in Epithelial Ovarian Cancers via the MAPK/ERK Pathway

E3 ubiquitin ligase F-box only protein 22 (FBXO22), which targets the key regulators of cellular activities for ubiquitylation and degradation, plays an important role in tumorigenesis and metastasis. However, the function of FBXO22 in epithelial ovarian cancers has not been reported. This study aims to explore the biological function of FBXO22 in epithelial ovarian cancers progression and metastasis and its specific regulation mechanism. Immunohistochemistry analysis of tissue microarray was performed to evaluate the expression of FBXO22 in epithelial ovarian cancers patients. The proliferative ability of epithelial ovarian cancers cells was examined by the CCK8. The metastasis ability was detected by the wound healing assay, migration and invasion assays. Western blot was used to verify the relationship between FBXO22 expression and mitogen-activated protein kinase related proteins. Autophagic flux was detected by electron microscopy, mRFP-GFP-LC3 adenovirus, lysosomal tracker and western blot. For in vivo experiments, the effect of FBXO22 on epithelial ovarian cancers resistance was observed in a xenograft tumor model and a metastatic mice model. We found that FBXO22 expression was significantly increased in epithelial ovarian cancers tissues and was closely correlated with clinical pathological factors. As a result, we found that FBXO22 promoted the growth and metastasis, as well as inhibited the autophagy flux. In addition, we identified that FBXO22 performed these functions via the MAPK/ERK pathway. Our results first reported the function of FBXO22 in epithelial ovarian cancer and the correlation between FBXO22 and autophagy, suggesting FBXO22 as a novel target of epithelial ovarian cancers assessment and treatment.

Downregulation of miR-223 promotes HMGB2 expression and induces oxidative stress to activate JNK and promote autophagy in an in vitro model of acute lung injury

Background

Excessive autophagic activity in alveolar epithelial cells is one of the main causes of acute lung injury (ALI), but the underlying molecular mechanism has not been fully elucidated. Previous studies have shown that microRNAs (miRs) are involved in regulating autophagy in several diseases. This study aimed to determine the role of miR-223 in excessive autophagic activity in alveolar epithelial cells and the underlying mechanism to identify a novel therapeutic targets for the development of new drugs to treat acute respiratory distress syndrome (ARDS).

Methods

A549 cells were treated with lipopolysaccharide (LPS) to establish an ALI in vitro model. The expression of miR-223 and its role of miR-223 in regulating oxidative stress and autophagy in the LPS-treated A549 cells, were examined using RT-PCR, flow cytometry and ELISA. A luciferase reporter assay was performed to verify the interaction between miR-223 and the high-mobility group box 2 (HMGB2) protein.

Results

The results showed that the LPS treatment downregulated miR-223 expression in alveolar epithelial cells. We further proved that miR-223 directly targeted the 3-untranslated region of the HMGB2 gene and the downregulation of miR-223 increased HMGB2 protein level, which activated the JNK signalling pathway and thus induced oxidative stress and autophagy in LPS-treated alveolar epithelial cells. Knockdown of HMGB2 protein deactivated the JNK signalling pathway and inhibited autophagy and oxidative stress in alveolar epithelial cells.

Conclusions

The results of this study suggest that miR-223 regulates oxidative stress and autophagy in alveolar epithelial cells by targeting HMGB2 via the JNK signalling pathway.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12950-021-00295-3.

Protective effects of anti-HMGB1 monoclonal antibody on lung ischemia reperfusion injury in mice

During ischemia reperfusion (IR) injury, high mobility group box 1 (HMGB1), a chromatin binding protein, is released from necrotic cells and triggers inflammatory responses. We assessed the therapeutic effect of a neutralizing anti-HMGB1 monoclonal antibody (mAb) on lung IR injury. A murine hilar clamp model of IR was used, where mice were divided into sham and IR groups with intravenous administration of anti-HMGB 1 mAb or control mAb. We analyzed the effect of anti-HMGB1 mAb against IR injury by assessing lung oxygenation, lung injury score, neutrophil infiltration, expression of proinflammatory cytokines and chemokines, levels of mitogen-activated protein kinase (MAPK) signaling, and measurement of apoptotic cells. Anti-HMGB1 mAb significantly decreased the plasma level of HMGB1 elevated by IR. The severity of IR injury represented by oxygenation capacity, lung injury score, and neutrophil infiltration was significantly improved by anti-HMGB1 mAb treatment. The expression of proinflammatory factors, including IL-1β, IL-6, IL-12, TNF-α, CXCL-1, and CXCL-2, and phosphorylation of p38 MAPK were both significantly reduced by anti-HMGB1 mAb treatment. Furthermore, anti-HMGB1 mAb treatment suppressed apoptosis, as determined through TUNEL assays. Overall, anti-HMGB1 mAb ameliorated lung IR injury by reducing inflammatory responses and apoptosis. Our findings indicate that anti-HMGB1 mAb has potential for use as a therapeutic to improve IR injury symptoms during lung transplantation.

Therapeutic targets and interventional strategies in COVID-19: mechanisms and clinical studies

Owing to the limitations of the present efforts on drug discovery against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the lack of the understanding of the biological regulation mechanisms underlying COVID-19, alternative or novel therapeutic targets for COVID-19 treatment are still urgently required. SARS-CoV-2 infection and immunity dysfunction are the two main courses driving the pathogenesis of COVID-19. Both the virus and host factors are potential targets for antiviral therapy. Hence, in this study, the current therapeutic strategies of COVID-19 have been classified into "target virus" and "target host" categories. Repurposing drugs, emerging approaches, and promising potential targets are the implementations of the above two strategies. First, a comprehensive review of the highly acclaimed old drugs was performed according to evidence-based medicine to provide recommendations for clinicians. Additionally, their unavailability in the fight against COVID-19 was analyzed. Next, a profound analysis of the emerging approaches was conducted, particularly all licensed vaccines and monoclonal antibodies (mAbs) enrolled in clinical trials against primary SARS-CoV-2 and mutant strains. Furthermore, the pros and cons of the present licensed vaccines were compared from different perspectives. Finally, the most promising potential targets were reviewed, and the update of the progress of treatments has been summarized based on these reviews.

Therapeutic Potential of B-1a Cells in Intestinal Ischemia-reperfusion Injury

BACKGROUND

Acute mesenteric ischemia is a common surgical emergency. Restoration of blood flow is a critical objective of treating this pathology. However, many patients suffer from ischemia-reperfusion (I/R) injuries at the time of revascularization, requiring prolonged hospitalizations. B-1a cells are a subtype of B lymphocytes with roles in regulating inflammation and tissue injury by spontaneous release of natural IgM and IL-10. We hypothesized that treatment with B-1a cells protects mice from intestinal I/R.

METHODS

Mesenteric ischemia was induced in mice by placing a vascular clip on the superior mesenteric artery for 60 minutes. At the time of reperfusion, B-1a cells or PBS control were instilled into the peritoneal cavity (PerC) of mice. PerC lavage, blood, intestine, and lungs were collected 4 h after reperfusion. Serum organ injury and inflammatory markers such as ALT, AST, LDH, lactate, IL-6, as well as lung and gut histology and myeloperoxidase (MPO) were assessed.

RESULTS

In intestinal I/R, B-1a cell frequency and number in the PerC were significantly decreased compared to sham-operated mice. There was an increase in the serum levels of ALT, AST, LDH, lactate, and IL-6 when comparing the vehicle group with the sham group. These increases were significantly reduced in the B-1a cell treated group. B-1a cell treatment significantly decreased the intestine and lung injury scores as well as MPO content, compared to vehicle treated mice. B-1a cell treatment resulted in a reduction of apoptotic cells in these tissues. Serum IgM levels were decreased in intestinal I/R, while treatment with B-1a cells significantly increased their levels towards normal levels.

CONCLUSIONS

B-1a cell treatment at the time of mesenteric reperfusion ameliorates end organ damage and reduces systemic inflammation through the improvement of serum IgM levels. Preserving B-1a cells pool could serve as a novel therapeutic avenue in intestinal I/R injury.

MicroRNA-146a overexpression alleviates intestinal ischemia/reperfusion-induced acute lung injury in mice

Previous studies have shown that microRNAs (miRs), such as miR-146a play an important role in the pathogenesis of intestinal ischemia/reperfusion (I/R)-induced injury; however, the role of miR-146a in intestinal I/R-induced acute lung injury has not been elucidated. An intestinal I/R-induced injury mouse model was established in the present study by clamping the superior mesenteric artery and expression levels of miR-146a in intestinal and lung tissue samples were evaluated using reverse transcription-quantitative PCR (RT-qPCR). Intestinal and lung histopathological characteristics in mice with intestinal I/R-induced injury were assessed by hematoxylin and eosin staining, and mRNA and protein expression levels in intestinal and lung tissue samples were evaluated using RT-qPCR and western blotting, respectively. miR-146a expression was significantly downregulated in the intestinal and lung tissue samples of mice with intestinal I/R-induced injury. Intestinal I/R injury-induced histopathological changes in the lung and intestines, and pulmonary edema in mice transduced with an adenoviral miR-146a-overexpression vector (the miR-146a overexpression group) were alleviated. mRNA expression levels of TNF-α, IL-1β, IFN-γ and TGF-β1, and protein expression levels of TNF receptor-associated factor 6, phosphorylated-p65 NF-κB, cleaved caspase-3 and cleaved caspase-9 in lung and intestinal tissue samples were downregulated in I/R-miR-146a-overexpressing mice, compared with those from the I/R-negative control group. Thus, the present study identified that pre-treatment with the miR-146a overexpression vector alleviated intestinal I/R-induced acute lung injury in mice.

Potential biomarkers for the early prediction of SARS-COV-2 disease outcome

The current pandemic due to the fast spreading of SARS-CoV-2 infection has caused severe impairment in health, social, economic, scientific, and medical sectors across the globe. Owing to the not so well understood mechanism of disease pathogenesis in terms of variations in immune responses, there remains obscure why some of the patients who are infected by the novel SARS-CoV-2 develop an unpredictable clinical course that rapidly causes severe and deadly complications/manifestations. Currently, several assays are available for the confirmation of SARS-CoV-2 infection at the point of care. However, none of these assays can predict the severity of the COVID-19 disease. Thus, the identification of a prognostic biomarker that forecasts the condition of SARS-CoV-2 patients to develop a severe form of the disease could enable the clinicians for more efficient patient triage and treatment. In this regard, the present review describes the role of selected biomolecules that are crucially involved in the immune-pathogenesis of SARS-CoV-2 infection such as hyper-immune responsiveness, bradykinin storm and vascular leakage assuming these may serve as an effective prognostic biomarker in COVID-19 to understand the outcome of the disease. Based on the review, we also propose the development of a cost-effective SERS-based prognostic biosensor for the detection and quantification of biomolecules for use as a point-of-care system during a disease outbreak.

Autophagy, Unfolded Protein Response, and Neuropilin-1 Cross-Talk in SARS-CoV-2 Infection: What Can Be Learned from Other Coronaviruses

The COVID-19 pandemic is caused by the 2019-nCoV/SARS-CoV-2 virus. This severe acute respiratory syndrome is currently a global health emergency and needs much effort to generate an urgent practical treatment to reduce COVID-19 complications and mortality in humans. Viral infection activates various cellular responses in infected cells, including cellular stress responses such as unfolded protein response (UPR) and autophagy, following the inhibition of mTOR. Both UPR and autophagy mechanisms are involved in cellular and tissue homeostasis, apoptosis, innate immunity modulation, and clearance of pathogens such as viral particles. However, during an evolutionary arms race, viruses gain the ability to subvert autophagy and UPR for their benefit. SARS-CoV-2 can enter host cells through binding to cell surface receptors, including angiotensin-converting enzyme 2 (ACE2) and neuropilin-1 (NRP1). ACE2 blockage increases autophagy through mTOR inhibition, leading to gastrointestinal complications during SARS-CoV-2 virus infection. NRP1 is also regulated by the mTOR pathway. An increased NRP1 can enhance the susceptibility of immune system dendritic cells (DCs) to SARS-CoV-2 and induce cytokine storm, which is related to high COVID-19 mortality. Therefore, signaling pathways such as mTOR, UPR, and autophagy may be potential therapeutic targets for COVID-19. Hence, extensive investigations are required to confirm these potentials. Since there is currently no specific treatment for COVID-19 infection, we sought to review and discuss the important roles of autophagy, UPR, and mTOR mechanisms in the regulation of cellular responses to coronavirus infection to help identify new antiviral modalities against SARS-CoV-2 virus.

Ischemia-Reperfusion Injury in Lung Transplantation

Lung transplantation has been established worldwide as the last treatment for end-stage respiratory failure. However, ischemia–reperfusion injury (IRI) inevitably occurs after lung transplantation. The most severe form of IRI leads to primary graft failure, which is an important cause of morbidity and mortality after lung transplantation. IRI may also induce rejection, which is the main cause of mortality in recipients. Despite advances in donor management and graft preservation, most donor grafts are still unsuitable for transplantation. Although the pulmonary endothelium is the primary target site of IRI, the pathophysiology of lung IRI remains incompletely understood. It is essential to understand the mechanism of pulmonary IRI to improve the outcomes of lung transplantation. Therefore, we reviewed the state-of-the-art in the management of pulmonary IRI after lung transplantation. Recently, the ex vivo lung perfusion (EVLP) system has been clinically introduced worldwide. Various promising therapeutic strategies for the protection of the endothelium against IRI, including EVLP, inhalation therapy with therapeutic gases and substances, fibrinolytic treatment, and mesenchymal stromal cell therapy, are awaiting clinical application. We herein review the latest advances in the field of pulmonary IRI in lung transplantation.

Autophagy protects against cerebral ischemic reperfusion injury by inhibiting neuroinflammation

OBJECTIVE

To examine the effect of autophagy on cerebral damage caused by different models and test the hypothesis that its protection mechanism acts via inhibiting expression of neuroinflammatory mediators.

METHODS

Autophagy was induced by rapamycin treatment. Cerebral damage was induced using models of IL-6 treatment, oxygen glucose deprivation/reoxygenation (OGD/R) in vitro, and middle cerebral artery occlusion (MCAO) in vivo. The effect and mechanism of autophagy was examined and assessed in terms of cell viability, infarction size in brain tissue, neurological score, production of inflammatory mediators IL-1β and IL-6, transcription and protein expression of autophagy markers beclin-1 and LC-3II in different experimental groups.

RESULTS

Autophagy triggered by rapamycin could protect neurons from IL-6-induced injury and astrocytes from OGD/R-induced injury in vitro and in rat brain tissue from MCAO in vivo. Autophagy significantly increased cell viability, attenuated cerebral infarction and improved neurological scores. It also inhibited production of the IL-1β and IL-6 and elevated the expression of beclin-1 and LC-3II.

CONCLUSIONS

Autophagy can inhibit the inflammatory response and reduce cerebral I/R injury. There was a relationship between the extent of protection and (i) the level of the autophagic response, (ii) the stage of the cerebral I/R injury, and (iii) the time of intervention.

Combination of autophagy and NFE2L2/NRF2 activation as a treatment approach for neuropathic pain

Macroautophagy/autophagy, an evolutionarily conserved process, plays an important role in the regulation of immune inflammation and nervous system homeostasis. However, the exact role and mechanism of autophagy in pain is still unclear. Here, we showed that impaired autophagy flux mainly occurred in astrocytes during the maintenance of neuropathic pain. No matter the stage of neuropathic pain induction or maintenance, activation of autophagy relieved the level of pain, whereas inhibition of autophagy aggravated pain. Moreover, the levels of neuroinflammation and reactive oxygen species (ROS) were increased or decreased following autophagy inhibition or activation. Further study showed that inhibition of autophagy slowed the induction, but increased the maintenance of neuroinflammatory responses, which could be achieved by promoting the binding of TRAF6 (TNF receptor-associated factor 6) to K63 ubiquitinated protein, and increasing the levels of p-MAPK8/JNK (mitogen-activated protein kinase 8) and nuclear factor of kappa light polypeptide gene enhancer in B cells (NFKB/NF-κB). Impaired autophagy also reduced the protective effect of astrocytes on neurons against ROS stress because of the decrease in the level of glutathione released by astrocytes, which could be improved by activating the NFE2L2/NRF2 (nuclear factor, erythroid derived 2, like 2) pathway. We also demonstrated that simultaneous activation of autophagy and the NFE2L2 pathway further relieved pain, compared to activating autophagy alone. Our study provides an underlying mechanism by which autophagy participates in the regulation of neuropathic pain, and a combination of autophagy and NFE2L2 activation may be a new treatment approach for neuropathic pain.

Abbreviation: 3-MA: 3-methyladenine; 8-OHdG: 8-hydroxydeoxy-guanosine; ACTB: actin, beta; AMPAR: alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate receptor; ATG: autophagy-related; CAMK2/CaMKII: calcium/calmodulin-dependent protein kinase II; CCL7: chemokine (C-C motif) ligand 7; CGAS: cyclic GMP-AMP synthase; CQ: chloroquine; GABA: gamma-aminobutyrate; GCLC: glutamate-cysteine ligase, catalytic subunit; GFAP: glial fibrillary acidic protein; GSH: glutathione; HMOX1/HO-1: heme oxygenase 1; KEAP1: kelch-like ECH-associated protein 1; MAP1LC3/LC3-II: microtubule-associated protein 1 light chain 3 beta (phosphatidylethanolamine-conjugated form); MAPK: mitogen-activated protein kinase; MAPK1/ERK: mitogen-activated protein kinase 1; MMP2: matrix metallopeptidase 2; MAPK8/JNK: mitogen-activated protein kinase 8; MAPK14/p38: mitogen-activated protein kinase 14; NFE2L2/NRF2: nuclear factor, erythroid derived 2, like 2; NFKB/NF-κB: nuclear factor of kappa light polypeptide gene enhancer in B cells; ROS: reactive oxygen species; SLC12A5: solute carrier family 12, member 5; SNL: spinal nerve ligation; TLR4: toll-like receptor 4; TRAF6: TNF receptor-associated factor; TRP: transient receptor potential.

The Immune System in Transfusion-Related Acute Lung Injury Prevention and Therapy: Update and Perspective

As an initiator of respiratory distress, transfusion-related acute lung injury (TRALI) is regarded as one of the rare complications associated with transfusion medicine. However, to date, the pathogenesis of TRALI is still unclear, and specific therapies are unavailable. Understanding the mechanisms of TRALI may promote the design of preventive and therapeutic strategies. The immune system plays vital roles in reproduction, development and homeostasis. Sterile tissue damage, such as physical trauma, ischemia, or reperfusion injury, induces an inflammatory reaction that results in wound healing and regenerative mechanisms. In other words, in addition to protecting against pathogens, the immune response may be strongly associated with TRALI prevention and treatment through a variety of immunomodulatory strategies to inhibit excessive immune system activation. Immunotherapy based on immune cells or immunological targets may eradicate complications. For example, IL-10 therapy is a promising therapeutic strategy to explore further. This review will focus on ultramodern advances in our understanding of the potential role of the immune system in TRALI prevention and treatment.

Fractalkine Is Linked to the Necrosome Pathway in Acute Pulmonary Inflammation

Acute pulmonary inflammation affects over 10% of intensive care unit (ICU) patients and is associated with high mortality. Fractalkine (CX₃CL1) and its receptor, CX₃CR1, have been shown to affect pulmonary inflammation, but previous studies have focused on macrophages. In a murine model of acute pulmonary inflammation, we identified inflammatory hallmarks in C57BL/6J and CX₃CR1^−/− mice. Pulmonary inflammation was significantly enhanced in the CX₃CR1^−/− animals compared to the C57BL/6J animals, as assessed by microvascular permeability, polymorphonuclear neutrophil (PMN) migration into lung tissue and alveolar space. The CX₃CR1^−/− mice showed increased levels of apoptotic PMNs in the lungs, and further investigations revealed an increased activation of necrosome-related receptor-interacting serine/threonine-protein kinases 1 (RIPK1), 3 (RIPK3), and mixed-lineage kinase domain-like pseudokinase (MLKL). Phosphorylated MLKL leads to membrane rupture and damage-associated molecular pattern (DAMP) release, which further enhance inflammation. The release of DAMPs was significantly higher in the CX₃CR1^−/− mice and led to the activation of various cascades, explaining the increased inflammation. RIPK3 and MLKL inhibition improved the inflammatory response in human PMNs in vitro and confirmed our in vivo findings. In conclusion, we linked CX₃CL1 to the necrosome complex in pulmonary inflammation and demonstrated a pivotal role of the necrosome complex in human PMNs.

Endothelium-dependent remote signaling in ischemia and reperfusion: Alterations in the cardiometabolic continuum

Intact endothelial function plays a fundamental role for the maintenance of cardiovascular (CV) health. The endothelium is also involved in remote signaling pathway-mediated protection against ischemia/reperfusion (I/R) injury. However, the transfer of these protective signals into clinical practice has been hampered by the complex metabolic alterations frequently observed in the cardiometabolic continuum, which affect redox balance and inflammatory pathways. Despite recent advances in determining the distinct roles of hyperglycemia, insulin resistance (InR), hyperinsulinemia, and ultimately diabetes mellitus (DM), which define the cardiometabolic continuum, our understanding of how these conditions modulate endothelial signaling remains challenging. It is widely accepted that endothelial cells (ECs) undergo functional changes within the cardiometabolic continuum. Beyond vascular tone and platelet-endothelium interaction, endothelial dysfunction may have profound negative effects on outcome during I/R. In this review, we summarize the current knowledge of the influence of hyperglycemia, InR, hyperinsulinemia, and DM on endothelial function and redox balance, their influence on remote protective signaling pathways, and their impact on potential therapeutic strategies to optimize protective heterocellular signaling.

Effects of prolonged cold-ischemia on autophagy in the graft lung in a rat orthotopic lung transplantation model

INTRODUCTION

Ischemia-reperfusion (I/R) injury causes present challenges in the field of graft transplantation which is also a major contributor to early graft dysfunction or failure after organ transplantation. The study focuses on the effects of prolonged cold-ischemia (CI) on the autophagic activity in the graft lung in a rat orthotopic lung transplantation model.

MATERIAL AND METHODS

Donor lungs were preserved under CI conditions for different periods. An orthotopic lung transplantation model was developed, and the lung tissues from donor lungs subjected to CI preservation and reperfusion were harvested. We evaluated the effects of different CI periods on autophagy, reactive oxygen species (ROS) and glucose consumption. Additionally, the mechanism by which prolonged CI affected autophagy was investigated through determination of the molecules related to the mTOR pathway after treatment with 3-Methyladenine (3-MA), rapamycin and an adenosine triphosphate (ATP) synthase inhibitor oligomycin (OM).

RESULTS

Prolonged CI led to increased activities of key glycolytic enzymes, glucose consumption and lactic acid production. Autophagy, ROS and glucose consumption were induced in the graft lung after I/R, which reached peak levels after 6 h and was gradually decreased. Most importantly, the perfusion treatment of 3-MA or OM decreased ROS level and autophagy, but increased the extent of mTOR phosphorylation, while the perfusion treatment of rapamycin induced ROS and autophagy.

CONCLUSION

Taken together, autophagy mediated by a prolonged CI preservation affects the glucose consumption and ROS production in the graft lung via the mTOR signaling pathway.

microRNA-145 Inhibition Upregulates SIRT1 and Attenuates Autophagy in a Mouse Model of Lung Ischemia/Reperfusion Injury via NF-κB-dependent Beclin 1

BACKGROUND

MicroRNA-145 (miR-145) has been shown to play a critical role in ischemia/reperfusion (I/R) injury; however, the expression and function of miR-145 in lung I/R injury have not been reported yet. This study aimed to elucidate the potential effects of miR-145 in lung I/R injury.

METHODS

Lung I/R mice models and hypoxia/reoxygenation (H/R) pulmonary microvascular endothelial cell models were established. The expression of miR-145 and sirtuin 1 (SIRT1) was measured with reverse transcription-quantitative polymerase chain reaction and Western blot analysis in mouse lung tissue and cells. Artificial modulation of miR-145 and SIRT1 (downregulation) was done in I/R mice and H/R cells. Additionally, Pao2/FiO2 ratio, wet weight-to-dry weight ratio, and cell apoptosis in mouse lung tissues were determined by blood gas analyzer, electronic balance, and deoxyuridine triphosphate-biotin nick end-labeling assay, respectively. Autophagy marker Beclin 1 and LC3 expression, NF-κB acetylation levels, and autophagy bodies were detected in cell H/R and mouse I/R models by Western blot analysis. pulmonary microvascular endothelial cell apoptosis was detected with flow cytometry.

RESULTS

miR-145 was abundantly expressed in the lung tissue of mice and PMVECs following I/R injury. In addition, miR-145 directly targeted SIRT1, which led to significantly decreased Pao2/FiO2 ratio and increased wet weight-to-dry weight ratio, elevated acetylation levels and transcriptional activity of NF-κB, upregulated expressions of tumor necrosis factor-α, interleukins-6, and Beclin 1, autophagy bodies, cell apoptosis, as well as LC3-II/LC3I ratio.

CONCLUSIONS

In summary, miR-145 enhances autophagy and aggravates lung I/R injury by promoting NF-κB transcriptional activity via SIRT1 expression.

Bone marrow-derived mesenchymal stem cells modulate autophagy in RAW264.7 macrophages via the phosphoinositide 3-kinase/protein kinase B/heme oxygenase-1 signaling pathway under oxygen-glucose deprivation/restoration conditions

Background

Autophagy of alveolar macrophages is a crucial process in ischemia/reperfusion injury-induced acute lung injury (ALI). Bone marrow-derived mesenchymal stem cells (BM-MSCs) are multipotent cells with the potential for repairing injured sites and regulating autophagy. This study was to investigate the influence of BM-MSCs on autophagy of macrophages in the oxygen-glucose deprivation/restoration (OGD/R) microenvironment and to explore the potential mechanism.

Methods

We established a co-culture system of macrophages (RAW264.7) with BM-MSCs under OGD/R conditions in vitro. RAW264.7 cells were transfected with recombinant adenovirus (Ad-mCherry-GFP-LC3B) and autophagic status of RAW264.7 cells was observed under a fluorescence microscope. Autophagy-related proteins light chain 3 (LC3)-I, LC3-II, and p62 in RAW264.7 cells were detected by Western blotting. We used microarray expression analysis to identify the differently expressed genes between OGD/R treated macrophages and macrophages co-culture with BM-MSCs. We investigated the gene heme oxygenase-1 (HO-1), which is downstream of the phosphoinositide 3-kinase/protein kinase B (PI3K/Akt) signaling pathway.

Results

The ratio of LC3-II/LC3-I of OGD/R treated RAW264.7 cells was increased (1.27 ± 0.20 vs. 0.44 ± 0.08, t = 6.67, P < 0.05), while the expression of p62 was decreased (0.77 ± 0.04 vs. 0.95 ± 0.10, t = 2.90, P < 0.05), and PI3K (0.40 ± 0.06 vs. 0.63 ± 0.10, t = 3.42, P < 0.05) and p-Akt/Akt ratio was also decreased (0.39 ± 0.02 vs. 0.58 ± 0.03, t = 9.13, P < 0.05). BM-MSCs reduced the LC3-II/LC3-I ratio of OGD/R treated RAW264.7 cells (0.68 ± 0.14 vs. 1.27 ± 0.20, t = 4.12, P < 0.05), up-regulated p62 expression (1.10 ± 0.20 vs. 0.77 ± 0.04, t = 2.80, P < 0.05), and up-regulated PI3K (0.54 ± 0.05 vs. 0.40 ± 0.06, t = 3.11, P < 0.05) and p-Akt/Akt ratios (0.52 ± 0.05 vs. 0.39 ± 0.02, t = 9.13, P < 0.05). A whole-genome microarray assay screened the differentially expressed gene HO-1, which is downstream of the PI3K/Akt signaling pathway, and the alteration of HO-1 mRNA and protein expression was consistent with the data on PI3K/Akt pathway.

Conclusions

Our results suggest the existence of the PI3K/Akt/HO-1 signaling pathway in RAW264.7 cells under OGD/R circumstances in vitro, revealing the mechanism underlying BM-MSC-mediated regulation of autophagy and enriching the understanding of potential therapeutic targets for the treatment of ALI.

Myocardial ischemia-reperfusion induced cardiac extracellular vesicles harbour proinflammatory features and aggravate heart injury

Extracellular vesicles (EVs) curb important biological functions. We previously disclosed that ischemia-reperfusion (IR) induces increased release of EVs (IR-EVs) in the heart. However, the role of IR-EVs in IR pathological process remains poorly understood. Here we found that adoptive transfer of IR-EVs aggravated IR induced heart injury, and EV inhibition by GW4869 reduced the IR injury. Our in vivo and in vitro investigations substantiated that IR-EVs facilitated M1-like polarization of macrophages with increased expression of proinflammatory cytokines. Further, we disclosed the miRNA profile in cardiac EVs and confirmed the enrichment of miRNAs, such as miR-155-5p in IR-EVs compared to EVs from the sham heart (S-EVs). In particular, IR-EVs transferred miR-155-5p to macrophages and enhanced the inflammatory response through activating JAK2/STAT1 pathway. Interestingly, IR-EVs not only boosted the local inflammation in the heart, but even triggered systemic inflammation in distant organs. Taken together, we newly identify an IR-EVs-miR-155-5p-M1 polarization axis in the heart post IR. The EVs derived from IR-injured heart contribute to both local and systemic inflammation. Importantly, EV inhibition by GW4869 is supposed to be a promising therapeutic strategy for IR injury.

Overview of COVID-19 inflammatory pathogenesis from the therapeutic perspective

The novel beta coronavirus (SARS-CoV-2, designated as COVID-19) that is responsible for severe acute respiratory syndrome has devastated the global economy and health care system. Since COVID-19 changed the definition of “normal” in ordinary life around the world, the development of effective therapeutics and preventive measures is desperately needed to fight SARS-CoV-2 infection and restore normalcy. A clear understanding of COVID-19 pathogenesis is crucial in providing the scientific rationale necessary to develop anti-COVID19 drugs and vaccines. According to the most recently published literature, COVID-19 pathogenesis was postulated to occur in three sequential phases: pulmonary, proinflammatory, and prothrombic. Herein, virus-host interactions, potential pathogenic mechanisms, and clinical manifestations are described for each phase. Additionally, based on this pathogenesis model, various therapeutic strategies involving current clinical trials are presented with an explanation of their modes of action and example drugs. This review is a thorough, updated summary of COVID-19 pathogenesis and the therapeutic options available for this disease.

Taming the Autophagy as a Strategy for Treating COVID-19

Currently, an efficient treatment for COVID-19 is still unavailable, and people are continuing to die from complications associated with SARS-CoV-2 infection. Thus, the development of new therapeutic approaches is urgently needed, and one alternative is to target the mechanisms of autophagy. Due to its multifaceted role in physiological processes, many questions remain unanswered about the possible advantages of inhibiting or activating autophagy. Based on a search of the literature in this field, a novel analysis has been made to highlight the relation between the mechanisms of autophagy in antiviral and inflammatory activity in contrast with those of the pathogenesis of COVID-19. The present analysis reveals a remarkable coincidence between the uncontrolled inflammation triggered by SARS-CoV-2 and autophagy defects. Particularly, there is conclusive evidence about the substantial contribution of two concomitant factors to the development of severe COVID-19: a delayed or absent type I and III interferon (IFN-I and IFN-III) response together with robust cytokine and chemokine production. In addition, a negative interplay exists between autophagy and an IFN-I response. According to previous studies, the clinical decision to inhibit or activate autophagy should depend on the underlying context of the pathological timeline of COVID-19. Several treatment options are herein discussed as a guide for future research on this topic.

Roles of TRAFs in Ischemia-Reperfusion Injury

Tumor necrosis factor receptor-associated factor (TRAF) proteins are a family of signaling molecules that function downstream of multiple receptor signaling pathways, and they play a pivotal role in the regulation of intracellular biological progresses. These TRAF-dependent signaling pathways and physiological functions have been involved in the occurrence and progression of ischemia-reperfusion injury (IRI), which is a common pathophysiological process that occurs in a wide variety of clinical events, including ischemic shock, organ transplantation, and thrombolytic therapy, resulting in a poor prognosis and high mortality. IRI occurs in multiple organs, including liver, kidney, heart, lung, brain, intestine, and retina. In recent years, mounting compelling evidence has confirmed that the genetic alterations of TRAFs can cause subversive phenotype changes during IRI of those organs. In this review, based on current knowledge, we summarized and analyzed the regulatory effect of TRAFs on the IRI of various organs, providing clear direction and a firm theoretical basis for the development of treatment strategies to manipulate TRAF proteins or TRAF-dependent signaling pathways in IRI-related diseases.

Inhibition of ACSL4 attenuates ferroptotic damage after pulmonary ischemia-reperfusion

Lung ischemia-reperfusion (IR) injury is a common clinical pathology associated with high mortality. Ferroptosis, a novel mode of cell death elicited by iron-dependent phospholipid peroxidation, has been implicated in ischemic events. Acyl-CoA synthetase long-chain family member 4 (ACSL4) is one of the main enzymes in pro-ferroptotic lipid metabolism. In this study, the involvement of ferroptotic death in different durations of reperfusion was evaluated by assessing the iron content, malondialdehyde, and glutathione levels, ferroptosis-related protein expression, and mitochondria morphology. The roles of ferroptosis-specific inhibitor, liproxastin-1 (Lip-1), and ACSL4 modulation in a preventive regimen were assessed in vivo and in vitro. The hallmarks of pulmonary function, such as histological lung injury score, wet/dry ratio, and oxygenation index, were evaluated as well. Results showed that lung IR increased the tissue iron content and lipid peroxidation accumulation, along with key protein (GPX4 and ACSL4) expression alteration during reperfusion. Pretreatment with Lip-1 inhibited ferroptosis and ameliorated lung IR-induced injury in animal and cell models. In addition, administering ACSL4 inhibitor rosiglitazone before ischemia diminished the ferroptotic damage in IR-injured lung tissue, consistent with the protective effect of ACSL4 knockdown on lung epithelial cells subjected to hypoxia/reoxygenation. Thus, this study delineated that IR-induced ferroptotic cell death in lung tissue and ACSL4 were correlated with this process. Inhibition of ferroptosis and ACSL4 mitigated the ferroptotic damage in IR-induced lung injury by reducing lipid peroxidation and increasing the glutathione and GPX4 levels.

SARS-CoV-2 multifaceted interaction with the human host. Part II: Innate immunity response, immunopathology, and epigenetics

The SARS-CoV-2 makes its way into the cell via the ACE2 receptor and the proteolytic action of TMPRSS2. In response to the SARS-CoV-2 infection, the innate immune response is the first line of defense, triggering multiple signaling pathways to produce interferons, pro-inflammatory cytokines and chemokines, and initiating the adaptive immune response against the virus. Unsurprisingly, the virus has developed strategies to evade detection, which can result in delayed, excessive activation of the innate immune system. The response elicited by the host depends on multiple factors, including health status, age, and sex. An overactive innate immune response can lead to a cytokine storm, inflammation, and vascular disruption, leading to the vast array of symptoms exhibited by COVID-19 patients. What is known about the expression and epigenetic regulation of the ACE2 gene and the various players in the host response are explored in this review.