LipoxinA4 attenuates acute pancreatitis-associated acute lung injury by regulating AQP-5 and MMP-9 expression, anti-apoptosis and PKC/SSeCKS-mediated F-actin activation

Aquaporin-5 Dynamic Regulation

Aquaporin-5 (AQP5), belonging to the aquaporins (AQPs) family of transmembrane water channels, facilitates osmotically driven water flux across biological membranes and the movement of hydrogen peroxide and CO₂. Various mechanisms have been shown to dynamically regulate AQP5 expression, trafficking, and function. Besides fulfilling its primary water permeability function, AQP5 has been shown to regulate downstream effectors playing roles in various cellular processes. This review provides a comprehensive overview of the current knowledge of the upstream and downstream effectors of AQP5 to gain an in-depth understanding of the physiological and pathophysiological processes involving AQP5.

Identification of novel immune-related targets mediating disease progression in acute pancreatitis

Introduction

Acute pancreatitis (AP) is an inflammatory disease with very poor outcomes. However, the order of induction and coordinated interactions of systemic inflammatory response syndrome (SIRS) and compensatory anti-inflammatory response syndrome (CARS) and the potential mechanisms in AP are still unclear.

Methods

An integrative analysis was performed based on transcripts of blood from patients with different severity levels of AP (GSE194331), as well as impaired lung (GSE151572), liver (GSE151927) and pancreas (GSE65146) samples from an AP experimental model to identify inflammatory signals and immune response-associated susceptibility genes. An AP animal model was established in wild-type (WT) mice and Tlr2-deficient mice by repeated intraperitoneal injection of cerulein. Serum lipase and amylase, pancreas impairment and neutrophil infiltration were evaluated to assess the effects of Tlr2 in vivo.

Results

The numbers of anti-inflammatory response-related cells, such as M2 macrophages (P = 3.2 × 10^-3), were increased with worsening AP progression, while the numbers of pro-inflammatory response-related cells, such as neutrophils (P = 3.0 × 10^-8), also increased. Then, 10 immune-related AP susceptibility genes (SOSC3, ITGAM, CAMP, FPR1, IL1R1, TLR2, S100A8/9, HK3 and MMP9) were identified. Finally, compared with WT mice, Tlr2-deficient mice exhibited not only significantly reduced serum lipase and amylase levels after cerulein induction but also alleviated pancreatic inflammation and neutrophil accumulation.

Discussion

In summary, we discovered SIRS and CARS were stimulated in parallel, not activated consecutively. In addition, among the novel susceptibility genes, TLR2might be a novel therapeutic target that mediates dysregulation of inflammatory responses during AP progression.

Application of Precision-Cut Lung Slices as an In Vitro Model for Research of Inflammatory Respiratory Diseases

The leading cause of many respiratory diseases is an ongoing and progressive inflammatory response. Traditionally, inflammatory lung diseases were studied primarily through animal models, cell cultures, and organoids. These technologies have certain limitations, despite their great contributions to the study of respiratory diseases. Precision-cut lung slices (PCLS) are thin, uniform tissue slices made from human or animal lung tissue and are widely used extensively both nationally and internationally as an in vitro organotypic model. Human lung slices bridge the gap between in vivo and in vitro models, and they can replicate the living lung environment well while preserving the lungs' basic structures, such as their primitive cells and trachea. However, there is no perfect model that can completely replace the structure of the human lung, and there is still a long way to go in the research of lung slice technology. This review details and analyzes the strengths and weaknesses of precision lung slices as an in vitro model for exploring respiratory diseases associated with inflammation, as well as recent advances in this field.

Protective effects of the notoginsenoside R1 on acute lung injury by regulating the miR-128-2-5p/Tollip signaling pathway in rats with severe acute pancreatitis

Notoginsenoside R1 (NG-R1), the extract and the main ingredient of Panax notoginseng, has anti-inflammatory effects and can be used in treating acute lung injury (ALI). In this study, we explored the pulmonary protective effect and the underlying mechanism of the NG-R1 on rats with ALI induced by severe acute pancreatitis (SAP). MiR-128-2-5p, ERK1, Tollip, HMGB1, TLR4, IκB, and NF-κB mRNA expression levels were measured using real-time qPCR, and TLR4, Tollip, HMGB1, IRAK1, MyD88, ERK1, NF-κB65, and P-IκB-α protein expression levels using Western blot. The NF-κB and the TLR4 activities were determined using immunohistochemistry, and TNF-α, IL-6, IL-1β, and ICAM-1 levels in the bronchoalveolar lavage fluid (BALF) using ELISA. Lung histopathological changes were observed in each group. NG-R1 treatment reduced miR-128-2-5p expression in the lung tissue, increased Tollip expression, inhibited HMGB1, TLR4, TRAF6, IRAK1, MyD88, NF-κB65, and p-IκB-α expression levels, suppressed NF-κB65 and the TLR4 expression levels, reduced MPO activity, reduced TNF-α, IL-1β, IL-6, and ICAM-1 levels in BALF, and alleviated SAP-induced ALI. NG-R1 can attenuate SAP-induced ALI. The mechanism of action may be due to a decreased expression of miR-128-2-5p, increased activity of the Tollip signaling pathway, decreased activity of HMGB1/TLR4 and ERK1 signaling pathways, and decreased inflammatory response to SAP-induced ALI. Tollip was the regulatory target of miR-128-2-5p.

Effects of Indwelling Pleural Catheter on Severe Acute Pancreatitis: A Retrospective Study

Background. Pleural effusion (PE) is an important predictor for severity and prognosis of severe acute pancreatitis (SAP). However, there are few studies focused on the effects and timing of indwelling pleural catheter (IPC) on SAP. Considering this, we designed a retrospective study to verify the relationship between PE and severity of SAP and observe the effects and timing of IPC in SAP. Methods. A total of 309 SAP patients were enrolled. Based on the presence or absence of PE and IPC and IPC time, the enrolled patients were divided into 6 groups. Then, baseline parameters, disease severity, critical complications, ventilator supporting time (VST), length of stay (LOS), and 60-day mortality were compared between each two groups. Results. PE was a risk factor for death of SAP, but not an independent risk factor. SAP patients with PE rather without PE had higher critical complication rates ( $p<0.001$ ), along with longer VST ( $p<0.001$ ) and LOS ( $p<0.001$ ). And the critical complication rates were lower in group 1 (IPC within 1 week of onset) than group 2 (IPC after 1 week of onset). Further, patients in group 1 also had shorter LOS ( $p=0.042$ ) and VST ( $p=0.001$ ) than those in group 2. In addition, the survival analysis showed the risk of death in the PE group was higher than the non-PE group (HR 6.6, 95% CI, 3.67–11.86, and $p<0.001$ ). And the risk of death in group 1 was lower than group 2 (HR 0.26, 95% CI, 0.08–0.84, and $p=0.025$ ). Conclusions. PE is a risk factor for death of SAP, but not an independent risk factor. IPC, especially IPC within 1 week of onset, has clinical practical value in SAP.

Signal Pathways and Markers Involved in Acute Lung Injury Induced by Acute Pancreatitis

Acute pancreatitis (AP) is a common acute abdominal disease with a mortality rate of about 30%. Acute lung injury (ALI) is a common systemic complication of acute pancreatitis, with progressive hypoxemia and respiratory distress as the main manifestations, which can develop into acute respiratory distress syndrome or even multiple organ dysfunction syndrome (MODS) in severe cases, endangering human health. In the model of AP, pathophysiological process of the lung can be summarized as oxidative stress injury, inflammatory factor infiltration, and alveolar cell apoptosis. However, the intrinsic mechanisms underlying AP and how it leads to ALI are not fully understood. In this paper, we summarize recent articles related to AP leading to ALI, including the signal transduction pathways and biomarkers of AP-ALI. There are factors or pathway aggravating ALI, the JAK2-STAT3 signaling pathway, NLRP3/NF-κB pathway, mitogen-activated protein kinase, PKC pathway, neutrophil protease (NP)-LAMC2-neutrophil pathway, and the P2X7 pathway, and there are important transcription factors in the NRF2 signal transduction pathway which could give researchers better understanding of the underlying mechanisms controlling AP and ALI and lay the foundation for finally curing ALI induced by AP.

Review of the potential of mesenchymal stem cells for the treatment of infectious diseases

The therapeutic value of mesenchymal stem cells (MSCs) for the treatment of infectious diseases and the repair of disease-induced tissue damage has been explored extensively. MSCs inhibit inflammation, reduce pathogen load and tissue damage encountered during infectious diseases through the secretion of antimicrobial factors for pathogen clearance and they phagocytose certain bacteria themselves. MSCs dampen tissue damage during infection by downregulating the levels of pro-inflammatory cytokines, and inhibiting the excessive recruitment of neutrophils and proliferation of T cells at the site of injury. MSCs aid in the regeneration of damaged tissue by differentiating into the damaged cell types or by releasing paracrine factors that direct tissue regeneration, differentiation, and wound healing. In this review, we discuss in detail the various mechanisms by which MSCs help combat pathogens, tissue damage associated with infectious diseases, and challenges in utilizing MSCs for therapy.

Pulmonary Edema in COVID-19 Patients: Mechanisms and Treatment Potential

COVID-19 mortality is primarily driven by abnormal alveolar fluid metabolism of the lung, leading to fluid accumulation in the alveolar airspace. This condition is generally referred to as pulmonary edema and is a direct consequence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. There are multiple potential mechanisms leading to pulmonary edema in severe Coronavirus Disease (COVID-19) patients and understanding of those mechanisms may enable proper management of this condition. Here, we provide a perspective on abnormal lung humoral metabolism of pulmonary edema in COVID-19 patients, review the mechanisms by which pulmonary edema may be induced in COVID-19 patients, and propose putative drug targets that may be of use in treating COVID-19. Among the currently pursued therapeutic strategies against COVID-19, little attention has been paid to abnormal lung humoral metabolism. Perplexingly, successful balance of lung humoral metabolism may lead to the reduction of the number of COVID-19 death limiting the possibility of healthcare services with insufficient capacity to provide ventilator-assisted respiration.

Daphnetin ameliorates acute lung injury in mice with severe acute pancreatitis by inhibiting the JAK2-STAT3 pathway

Severe acute pancreatitis (SAP) is often associated with pulmonary inflammation leading to acute lung injury. Daphnetin, a natural coumarin derivative, has been reported to exert anti-inflammatory effects. Here, we explored the effect and possible mechanism of daphnetin in a mouse model of SAP-associated lung injury induced by an intraperitoneal injection of L-arginine. The severity of pancreatic and lung injury is determined by histology and its score. Immunostaining of inflammatory and apoptotic cells was used to demonstrate lung tissue inflammation and apoptosis; ELISA analysis of serum and tissue cytokine levels; and western blotting and immunohistochemical staining for the activated Janus kinase 2 (JAK2)-signal transducer and activator of transcription protein 3 (STAT3) signalling pathway in lung tissues. Daphnetin pretreatment significantly reduced SAP-induced pancreatic and lung tissue damage, reduced interleukin-6 and tumour necrosis factor-α concentrations in both serum and lung tissues, reduced serum amylase and myeloperoxidase activities, and reduced macrophage (CD11b) and neutrophil (Ly6G) infiltration and cell apoptosis in the lung tissue. Moreover, SAP-induced phosphorylation of JAK2 and STAT3 in the lung tissue was also significantly diminished by the daphnetin pretreatment. These results indicated that daphnetin reduces SAP-associated lung tissue damage, likely by inhibiting the activation of JAK2-STAT3 signalling.

The mechanism underlying hypaconitine-mediated alleviation of pancreatitis-associated lung injury through up-regulating aquaporin-1/TNF-α

BACKGROUND/AIMS

Acute pancreatitis-associated lung injury (APALI) is one of the most common and most dangerous form of extra-pancreatic organ damage in severe acute pancreatitis (SAP). The treatment options for SAP were limited thus far; as a result, approximately 60%-80% of patients with SAP would die within a week. Hypaconitine (HC), one of the most important active ingredients in a Mongolian traditional medicine Radix Aconiti Kusnezoffii has an excellent anti-inflammatory effect.

MATERIALS AND METHODS

To ascertain whether HC has a protective effect against APALI, we investigated the therapeutic effects and the underlying mechanisms in vivo and in vitro and attempted to elucidate the mechanism in detail. In this study, APALI rats and human pulmonary microvascular endothelial cells were treated with therapeutic doses of HC after establishing a model with sodium taurocholate and lipopolysaccharide, respectively.

RESULTS

Serum amylase and lipase activity, lung wet/dry weight ratio, lung myeloperoxidase activity, and pancreatic and lung histopathological changes showed that HC alleviated APALI in a dose-dependent way, which can be abolished by an aquaporin-1 (AQP-1) knockdown. The results of the reverse transcriptase polymerase chain reaction, Western blot, and immunohistochemical staining confirmed the expression of AQP-1, a kind of transmembrane protein that mainly distributed in the membranes of pulmonary cells and contributed to maintain water balance in the body by interacting with tumor necrosis factor-alpha (TNF-α), is negatively associated with APALI. On the contrary, HC treatment up-regulated AQP-1 expression and down-regulated the TNF-α expression as a consequence in APALI.

CONCLUSION

These results suggest that HC has a good anti-inflammatory therapeutic effect on APALI with a possible underlying mechanism that affects the AQP-1/TNF-α pathway.

Nimbolide ameliorates pancreatic inflammation and apoptosis by modulating NF-κB/SIRT1 and apoptosis signaling in acute pancreatitis model

Acute pancreatitis (AP) is a potential gastrointestinal problem most commonly associated with pancreatic inflammation and acinar cells injury. Nimbolide (NB), isolated from the tree Azadirachta indica, possesses antioxidant and anti-inflammatory effects. Here, we aimed to investigate the pancreatic protective effects of NB in ameliorating cerulein-induced pancreatic inflammation and apoptosis in AP model and evaluate the potential mechanism of action. AP was induced in Swiss albino mice by six-hourly intraperitoneal exposures of cerulein (50 µg/kg/hr) and pre-treatment of NB (0.3 and 1 mg/kg) 7 days prior to the cerulein exposure. Various parameters associated with AP in plasma and pancreatic tissues were evaluated. Severity of AP was effectively ameliorated by NB as shown by reducing pancreatic edema, plasma amylase and lipase levels, MPO levels and in cerulein-induced histological damage. Further, the antioxidant effect of NB was associated with a significant inhibition of oxidative-nitrosative stress in Raw 264.7 cells and cerulein-induced AP mice. Moreover, NB suppressed proinflammatory cytokines, iNOS and nitrotyrosine expression. In addition, NB inhibited NF-κB activation and increased SIRT1 expression in cerulein challenged mice. Furthermore, NB also inhibited pancreatic apoptosis by downregulating cleaved caspase 3 and Bax while upregulating Bcl2 expression in cerulein-treated mice. Inhibition of pancreatic inflammation and apoptosis resulted in attenuation of cerulein-induced AP. These results suggest that NB exerts strong anti-pancreatitis effects against cerulein-induced AP by combating inflammatory and apoptosis signaling via SIRT1 activation.

Aquaporins in lung health and disease: Emerging roles, regulation, and clinical implications

Aquaporins (AQPs) aka water channels are a family of conserved transmembrane proteins (~30 kDa monomers) expressed in various organ systems. Of the 13 AQPs (AQP0 through AQP12) in the human body, four (AQPs 1, 3, 4, and 5) are expressed in the respiratory system. These channels are conventionally known for mediating transcellular fluid movements. Certain AQPs (aquaglyceroporins) have the capability to transport glycerol and potentially other solutes. There is an emerging body of literature unveiling the non-conventional roles of AQPs such as in cell proliferation and migration, gas permeation, signal potentiation, etc. Initial gene knock-out studies established a physiological role for lung AQPs, particularly AQP5, in maintaining homeostasis, by mediating fluid secretion from submucosal glands onto the airway surface liquid (ASL) lining. Subsequent studies have highlighted the functional significance of AQPs, particularly AQP1 and AQP5 in lung pathophysiology and diseases, including but not limited to chronic and acute lung injury, chronic obstructive pulmonary disease (COPD), other inflammatory lung conditions, and lung cancer. AQP1 has been suggested as a potential prognostic marker for malignant mesothelioma. Recent efforts are directed toward exploiting AQPs as targets for diagnosis, prevention, intervention, and/or treatment of various lung conditions. Emerging information on regulatory pathways and directed mechanistic research are posited to unravel novel strategies for these clinical implications. Future considerations should focus on development of AQP inhibitors, blockers, and modulators for therapeutic needs, and better understanding the role of lung-specific AQPs in inter-individual susceptibility to chronic lung diseases such as COPD and cancer.

Macrophages in pancreatitis: Mechanisms and therapeutic potential

Macrophages play a crucial role in the pathogenesis of pancreatitis that is a common gastrointestinal disease. Particularly, macrophages differentiate into different phenotypes and exert diverse functions in acute pancreatitis (AP) and chronic pancreatitis (CP), respectively. In AP, macrophages in the pancreas and other related organs are mainly activated and differentiated into a pro-inflammatory M1 phenotype, and furthermore secrete inflammatory cytokines and mediators, causing local inflammation of the pancreas, and even intractable systemic inflammatory response or multiple organ failure. In CP, macrophages often exhibit a M2 polarisation and interact with pancreatic stellate cells (PSCs) in an autocrine and paracrine cytokine-dependent manner to promote the progression of pancreatic fibrosis. As the severity of pancreatic fibrosis aggravates, the proportion of M2/M1 macrophage cytokines in the pancreas increases. The discovery of macrophages in the pathogenesis of pancreatitis has promoted the research of targeted drugs, which provides great potential for the effective treatment of pancreatitis. This paper provides an overview of the roles of various macrophages in the pathogenesis of pancreatitis and the current research status of pancreatitis immunotherapy targeting macrophages. The findings addressed in this review are of considerable significance for understanding the pivotal role of macrophages in pancreatitis.

BML-111 inhibits EMT, migration and metastasis of TAMs-stimulated triple-negative breast cancer cells via ILK pathway

Triple-negative breast cancer (TNBC) has a more aggressive phenotype and higher metastasis and recurrence rates than other breast cancer subtypes. The immune microenvironment and hypoxic microenvironment of breast cancer constitute the survival environment of cancer cells, which is an important environment to support cancer cells. LXA₄ and its analog, BML-111 is an important regulator of inflammatory cytokines, which provides a possible way for the treatment of inflammatory-related tumors. Here, in the in vitro experiment, we showed that BML-111 could inhibit the EMT and migration of TAMs-stimulated TNBC by down-regulating ILK as well as p-Akt and p-GSK3β. And it could prevent the formation of breast cancer cell clusters. In the in vivo experiment, BML-111 could inhibit the metastasis of 4T1 breast cancer cells. We also demonstrated that BML-111 could affect macrophages in tumor microenvironment to prevent metastasis. These results showed that BML-111 could be a possible candidate for breast cancer therapy by targeting ILK and TAMs.

Acute respiratory distress syndrome in acute pancreatitis

Development of organ failure is one of the major determinants of mortality in patients with acute pancreatitis (AP). Acute respiratory distress syndrome (ARDS) is an important cause of respiratory failure in AP and is associated with high mortality. Pathogenesis of ARDS in AP is incompletely understood. Release of various cytokines plays an important role in development of ARDS in AP. Increased gut permeability due to various toxins, inflammatory mediators, and pancreatic enzymes potentiates lung injury by gut-lymph-lung axis leading on to increased translocation of bacterial endotoxins. Various scoring systems, serum levels of various cytokines and lung ultrasound have been evaluated for prediction of development of ARDS in AP with varying results. Various drugs have shown encouraging results in prevention of ARDS in animal models but these encouraging results in animal models are yet to be confirmed in clinical studies. There is no specific effective treatment for ARDS. Treatment of sepsis and local complications of AP should be done according to the standard management strategies. Lung protective ventilatory strategies are of paramount importance to improve outcome of patients of AP with ARDS and therefore effective coordination between gastroenterologists and intensivists is needed for effective management of these patients.

Lipoxin A4 Ameliorates Acute Pancreatitis-Associated Acute Lung Injury through the Antioxidative and Anti-Inflammatory Effects of the Nrf2 Pathway

Acute lung injury (ALI) is a critical event involved in the pathophysiological process of acute pancreatitis (AP). Many methods have been widely used for the treatment of AP-ALI, but few are useful during early inflammation. Lipoxin A4 (LXA4), a potent available anti-inflammatory and novel antioxidant mediator, has been extensively studied in AP-ALI, but its underlying mechanism as a protective mediator is not clear. This research was conducted to identify the possible targets and mechanisms involved in the anti-AP-ALI effect of LXA4. First, we confirmed that LXA4 strongly inhibited AP-ALI in mice. Next, using ELISA, PCR, and fluorescence detection to evaluate different parameters, LXA4 was shown to reduce the inflammatory cytokine production induced by AP and block reactive oxygen species (ROS) generation in vivo and in vitro. In addition, TNF-α treatment activated the nuclear factor E2-related factor 2 (Nrf2) signaling pathway and its downstream gene heme oxygenase-1 (HO-1) in human pulmonary microvascular endothelial cells (HPMECs), and LXA4 further promoted their expression. This study also provided evidence that LXA4 phosphorylates Ser40 and triggers its nuclear translocation to activate Nrf2. Moreover, when Nrf2-knockout (Nrf2^−/−) mice and cells were used to further assess the effect of the Nrf2/HO-1 pathway, we found that Nrf2 expression knockdown partially eliminated the effect of LXA4 on the reductions in inflammatory factor levels while abrogating the inhibitory effect of LXA4 on the ROS generation stimulated by AP-ALI. Overall, LXA4 attenuated the resolution of AP-induced inflammation and ROS generation to mitigate ALI, perhaps by modulating the Nrf2/HO-1 pathway. These findings have laid a foundation for the treatment of AP-ALI.

Lipoxin A4 ameliorates alveolar fluid clearance disturbance in lipopolysaccharide-induced lung injury via aquaporin 5 and MAPK signaling pathway

Background

A characteristic of acute lung injury (ALI) is the inflammatory damage of alveolar fluid transport. Lipoxins are endogenous lipids involving in the resolution of inflammation. It is found that lipoxin A4 (LXA4) has the distinct properties to improve the anti-edema and pro-resolution function in inflammation. Since aquaporins (AQPs) have essential roles in the integrity of barrier function during fluid transport, especially AQP5 in the maintaining of the epithelium permeability, the current study is aimed to evaluate the potential role of LXA4 in regulating alveolar fluid clearance (AFC) during fluid transport and the corresponding change of AQP5 in the lung.

Methods

ALI was induced by the lipopolysaccharide (LPS) intraperitoneal injection, and LXA4 treatment was given 8 hours after LPS administration. We investigated changes in the capacity of AFC, pro-inflammatory cytokine concentrations in bronchoalveolar lavage fluid (BALF) and the severity of ALI. Then AQP5 expression in lung tissue and potential regulatory pathways in LPS-induced ALI was explored.

Results

LXA4 treatment was found to inhibit AFC capacity, inflammatory cytokine release, partially, alleviate ALI severity, and restored AQP5 expression partially. Additionally, we found that LXA4 played a protective role by the inhibition of the phosphorylation of p38 and JNK.

Conclusions

In summary, our results suggest that LXA4 plays a protective role in lipopolysaccharide-induced ALI by restoring AFC capacity and upregulating AQP5 expression and inhibiting the phosphorylation of p38 and JNK. These findings suggest potential new mechanism of LXA4 as anti-inflammation therapy for the impairment of alveolar fluid transport in ALI.