Inhibition of poly (adenosine diphosphate-ribose) polymerase attenuates lung-kidney crosstalk induced by intratracheal lipopolysaccharide instillation in rats

Dexamethasone inhibited angiotensin II and its receptors to reduce sepsis-induced lung and kidney injury in rats

OBJECTIVES

To investigate the effect of dexamethasone (DXM) on acute lung and kidney injury with sepsis and its possible mechanism.

METHODS

Control (NC), lipopolysaccharide (LPS) and lipopolysaccharide + dexamethasone (LPS+DXM) treated groups were established by random assignment of 72 Wistar rats. The NC rats were injected with physiological saline, while the LPS group was injected with LPS (5 mg/kg) and LPS+DXM group was injected with LPS(5 mg/kg) first and followed by DXM (1 mg/kg). Serum tumor necrosis factor-α (TNF-α) and serum macrophage inflammatory protein 1α (MIP-1α) were measured by ELISA. Lung wet/dry weight ratio, serum creatinine(SCR) and blood urea nitrogen(BUN) were determined at various time points. Hematoxylin Eosin staining (HE) for pathological changes in the lung and kidney. Radioimmunoassay was used to detect the levels of angiotensin II (Ang II) in plasma, lung and kidney tissues. Immunohistochemistry and western blot (WB) were used to detect angiotensin II receptor type 1 (AT1R) protein and angiotensin II receptor type 2 (AT2R) protein in lung and kidney tissues. The level of nitric oxide (NO) in serum, lung and kidney were detected using nitrate reductase method.

RESULTS

Compared with control group, serum TNF-α, MIP-1α, SCR, BUN, lung W/D, Ang II level in plasma, lung and kidney, lung and kidney AT2R protein, NO level in serum, lung and kidney were significantly elevated(P<0.05) and pathological damage of lung and kidney tissues were showed in LPS group rats (P<0.05), whereas DXM down-regulated the above indexes and alleviate pathological damage of lung and kidney tissues. However, the expression of the lung and kidney AT1R protein was opposite to the above results.

CONCLUSIONS

Sepsis can cause acute lung and kidney injury and changes RAAS components in circulating, lung and renal. DXM can improve acute lung and kidney injury in septic rats, and the mechanism may be related to the down-regulation of inflammatory factors, AngII, AT2R, NO and up-regulation of AT1R expression by DXM.

Interorgan communication networks in the kidney-lung axis

The homeostasis and health of an organism depend on the coordinated interaction of specialized organs, which is regulated by interorgan communication networks of circulating soluble molecules and neuronal connections. Many diseases that seemingly affect one primary organ are really multiorgan diseases, with substantial secondary remote organ complications that underlie a large part of their morbidity and mortality. Acute kidney injury (AKI) frequently occurs in critically ill patients with multiorgan failure and is associated with high mortality, particularly when it occurs together with respiratory failure. Inflammatory lung lesions in patients with kidney failure that could be distinguished from pulmonary oedema due to volume overload were first reported in the 1930s, but have been largely overlooked in clinical settings. A series of studies over the past two decades have elucidated acute and chronic kidney-lung and lung-kidney interorgan communication networks involving various circulating inflammatory cytokines and chemokines, metabolites, uraemic toxins, immune cells and neuro-immune pathways. Further investigations are warranted to understand these clinical entities of high morbidity and mortality, and to develop effective treatments.

Primary graft dysfunction grade correlates with acute kidney injury stage after lung transplantation

BACKGROUND

Primary graft dysfunction (PGD) and acute kidney injury (AKI) are major early complications of lung transplantation and are associated with increased mortality. Lung injury after PGD can contribute to renal dysfunction; however, the association between PGD and AKI severity has not been thoroughly investigated. We analyzed the association between PGD grading and AKI staging, and the impact of AKI on subsequent changes to chronic kidney disease (CKD), including glomerular filtration rate (GFR), over time.

METHODS

This was a retrospective review of a single-center lung transplantation database between January 2018 and June 2022. AKI and GFR categories were classified according to the Kidney Disease: Improving Global Outcomes criteria. Spearman's and Kaplan-Meier tests were used to compare disease severity and assess survival.

RESULTS

In a total of 206 patients: 119 (57.8%), 25 (12.1%), 34 (16.5%), and 28 (13.6%) had PGD grades 0, 1, 2, and 3, respectively; 96 (46.6%), 47 (22.8%), 27 (13.1%), and 36 (17.5%) had AKI stages 0, 1, 2, and 3, respectively. Twenty-one of the 28 patients (75.0%) with PGD grade 3 had AKI stage 3. There was a significant correlation between PGD grade and AKI stage (P<0.001). There was also a significant correlation between AKI stage and GFR category of CKD at 3, 6, 9, and 12 months after lung transplantation (all P<0.001). For all AKI stages, GFR categories worsened with postoperative time.

CONCLUSIONS

PGD grade was significantly correlated with AKI stage, and AKI stage was correlated with GFR categories of CKD.

Organ Crosstalk in Acute Kidney Injury: Evidence and Mechanisms

Acute kidney injury (AKI) is becoming a public health problem worldwide. AKI is usually considered a complication of lung, heart, liver, gut, and brain disease, but recent findings have supported that injured kidney can also cause dysfunction of other organs, suggesting organ crosstalk existence in AKI. However, the organ crosstalk in AKI and the underlying mechanisms have not been broadly reviewed or fully investigated. In this review, we summarize recent clinical and laboratory findings of organ crosstalk in AKI and highlight the related molecular mechanisms. Moreover, their crosstalk involves inflammatory and immune responses, hemodynamic change, fluid homeostasis, hormone secretion, nerve reflex regulation, uremic toxin, and oxidative stress. Our review provides important clues for the intervention for AKI and investigates important therapeutic potential from a new perspective.

Nebulized Non-Immunogenic Staphylokinase in the Mice Acute Lung Injury Model

Acute lung injury (ALI) as a model of acute respiratory distress syndrome is characterized by inflammation, complex coagulation, and hematologic abnormalities which result in the formation of fibrin-platelet microthrombi in the pulmonary vessels with the rapid development of progressive respiratory dysfunction. We hypothesize that a nebulized fibrinolytic agent, non-immunogenic staphylokinase (nSta), may be useful for ALI therapy. First, the effect of the nebulized nSta (0.2 mg/kg, 1.0 mg/kg, or 2.0 mg/kg) on the coagulogram parameters was studied in healthy rats. ALI was induced in mice by nebulized administration of lipopolysaccharide (LPS) at a dose of 10 mg/kg. nSta (0.2 mg/kg, 0.4 mg/kg or 0.6 mg/kg) was nebulized 30 min, 24 h, and 48 h after LPS administration. The level of pro-inflammatory cytokines was determined in the blood on the 8th day after LPS and nSta administration. The assessment of lung damage was based on their weighing and microscopic analysis. Fibrin/fibrinogen deposition in the lungs was determined by immunohistochemistry. After nSta nebulization in healthy rats, the fibrinogen blood level as well as activated partial thromboplastin time and prothrombin time did not change. In the nebulized ALI model, the mice showed an increase in lung weight due to their edema and rising fibrin deposition. An imbalance of proinflammatory cytokines was also found. Forty percent of mice with ALI without nSta nebulization had died. Nebulized nSta at a dose of 0.2 mg/kg reduced the severity of ALI: a decrease in interstitial edema and inflammatory infiltration was noted. At a dose of 0.4 mg/kg of nebulized nSta, the animals showed no peribronchial edema and the bronchi had an open clear lumen. At a dose of 0.6 mg/kg of nebulized nSta, the manifestations of ALI were completely eliminated. A significant dose-dependent reduction of the fibrin-positive areas in the lungs of mice with ALI was established. Nebulized nSta had a normalizing effect on the proinflammatory cytokines in blood— interleukin (IL)-1α, IL-17A, IL-6, and granulocyte-macrophage colony-stimulating factor (GM-CSF). These data showed the effectiveness of nebulized nSta and the perspectives of its clinical usage in COVID-19 patients with acute respiratory distress syndrome (ARDS).

Structural Characterization and Anti-inflammatory Activity of a Galactorhamnan Polysaccharide From Citrus medica L. var. sarcodactylis

This study aimed to extract polysaccharides from Citrus medica L. var. sarcodactylis (finger citron fruits) and analyze their structures and potential bioactivities. A new polysaccharide named K-CMLP was isolated and purified by Diethylaminoethylcellulose (DEAE)-Sepharose Fast Flow and DEAE-52 cellulose column chromatography with an average molecular weight of 3.76 × 10³ kDa. Monosaccharide composition analysis revealed that K-CLMP consisted of rhamnose, galactose, and glucose, with a molar ratio of 6.75:5.87:1.00. Co-resolved by methylation and two-dimensional nuclear magnetic resonance (NMR), K-CLMP was alternately connected with 1, 2-Rha and 1, 4-Gal to form the backbone, and a small number of glucose residues was connected to O-4 of rhamnose. The results of DPPH⋅ and ABTS⁺⋅ radical scavenging assays indicated that both crude polysaccharide Citrus medica L. var. polysaccharide (CMLP) and K-CLMP exhibited strong free-radical-scavenging properties in a dose-dependent manner. In addition, K-CMLP significantly inhibited the production of pro-inflammatory cytokines (IL-6 and TNF-α) and reactive oxygen species (ROS) in RAW 264.7 cells treated with LPS. These results provide a basis for further use as one of the potential functions of food or natural medicine.

PARP Inhibitors: An Innovative Approach to the Treatment of Inflammation and Metabolic Disorders in Sepsis

Sepsis is not only a threat to the health of individual patients but also presents a serious epidemiological problem. Despite intensive research, modern sepsis therapy remains based primarily on antimicrobial treatment and supporting the functions of failing organs. Finding a cure for sepsis represents a great and as yet unfulfilled need in modern medicine. Research results indicate that the activity of poly (adenosine diphosphate (ADP)-ribose) polymerase (PARP) may play an important role in the inflammatory response and the cellular metabolic disorders found in sepsis. Mechanisms by which PARP-1 may contribute to inflammation and metabolic disorders include effects on the regulation of gene expression, impaired metabolism, cell death, and the release of alarmins. These findings suggest that inhibition of this enzyme may be a promising solution for the treatment of sepsis. In studies using experimental sepsis models, inhibition of PARP-1 has been shown to ameliorate the inflammatory response and increase survival. This action was described, among others, for olaparib, a PARP-1 inhibitor approved for use in oncology. While the results of current research are promising, the use of PARP inhibitors in non-oncological diseases raises some concerns, mainly related to the enzyme's role in deoxyribonucleic acid (DNA) repair. However, the results of studies on experimental models indicate the effectiveness of even short-term PARP-1 inhibition and do not confirm concerns regarding its impact on the integrity of nuclear DNA. Current research presents PARP inhibition as a potential solution for the treatment of sepsis and indicates the need for further research.

Poly(ADP-Ribose) Polymerase Inhibition in Acute Lung Injury. A Reemerging Concept

PARP1, the major isoform of a family of ADP-ribosylating enzymes, has been implicated in the regulation of various biological processes including DNA repair, gene transcription, and cell death. The concept that PARP1 becomes activated in acute lung injury (ALI) and that pharmacological inhibition or genetic deletion of this enzyme can provide therapeutic benefits emerged over 20 years ago. The current article provides an overview of the cellular mechanisms involved in the pathogenetic roles of PARP1 in ALI and provides an overview of the preclinical data supporting the efficacy of PARP (poly[ADP-ribose] polymerase) inhibitors. In recent years, several ultrapotent PARP inhibitors have been approved for clinical use (for the therapy of various oncological diseases): these newly-approved PARP inhibitors were recently reported to show efficacy in animal models of ALI. These observations offer the possibility of therapeutic repurposing of these inhibitors for patients with ALI. The current article lays out a potential roadmap for such repurposing efforts. In addition, the article also overviews the scientific basis of potentially applying PARP inhibitors for the experimental therapy of viral ALI, such as coronavirus disease (COVID-19)-associated ALI.

Pharmacological inhibition of poly (ADP-ribose) polymerase by olaparib ameliorates influenza-virus-induced pneumonia in mice

Treatments against influenza A viruses (IAV) have to be updated regularly due to antigenic drift and drug resistance. Poly (ADP-ribose) polymerases (PARPs) are considered effective therapeutic targets of acute lung inflammatory injury. This study aimed to explore the effects of PARP-1 inhibitor olaparib on IAV-induced lung injury and the underlying mechanisms. Male wild-type C57BL/6 mice were intranasally infected with IAV strain H1N1 to mimic pneumonia experimentally. Olaparib at different doses was intraperitoneally injected 2 days before and 5 consecutive days after virus stimulation. On day 6 post-infection, lung tissues as well as bronchoalveolar lavage fluid (BALF) were sampled for histological and biochemical analyses. Olaparib increased the survival rate of IAV mice dose-dependently. Olaparib remarkably reduced IAV mRNA expression, myeloperoxidase (MPO) level, and inflammatory cell infiltration in IAV lungs. Moreover, olaparib significantly reduced the level of interleukin (IL)-1β, tumor necrosis factor (TNF)-α, interferon (IFN)-γ, IL-6, and IL-4 and increased IL-10 in IAV lungs. Also, olaparib efficiently reduced IL-6, monocyte chemotactic protein (MCP)-1, granulocyte colony-stimulating factor (G-CSF), TNF-α, chemokine (C–X–C motif) ligand (CXCL)1, CXCL10, chemokine (C–C motif) ligand (CCL)3, and regulated on activation, normal T cell expressed and secreted (RANTES) release in IAV BALF. Olaparib decreased PARylated protein content and p65, IκBα phosphorylation in IAV lung tissues. This study successfully constructed the pneumonia murine model using IAV. Olaparib decreased IAV-induced mortality in mice, lung injury, and cytokine production possibly via modulation of PARP-1/NF-κB axis.

Surfactant protein D attenuates acute lung and kidney injuries in pneumonia-induced sepsis through modulating apoptosis, inflammation and NF-κB signaling

Pneumonia and sepsis are major risk factors for acute kidney injury (AKI). Patients with pneumonia and AKI are at increased risk for morbidity and mortality. Surfactant protein D (SP-D) expressed in lung and kidney plays important roles in innate immunity. However, little is known about the role of organ-specific SP-D in the sepsis. The current study uses wild type (WT), SP-D knockout (KO), and humanized SP-D transgenic (hTG, lung-specific SP-D expression) mice to study organ-specific role of SP-D in pneumonia-induced sepsis. Analyses demonstrated differential lung and kidney injury among three-type mice infected with Pseudomonas aeruginosa. After infection, KO mice showed higher injurious scores in both lung and kidney, and decreased renal function than WT and hTG mice. hTG mice exhibited comparable lung injury but more severe kidney injury compared to WT mice. Increased renal tubular apoptosis, NF-κB activation and proinflammatory cytokines in the kidney of KO mice were found when compared with WT and hTG mice. Furthermore, in vitro primary proximal tubular epithelial cells from KO mice showed more apoptosis with higher level of activated caspase-3 than those from WT mice after LPS treatment. Collectively, SP-D attenuates AKI in the sepsis by modulating renal apoptosis, inflammation and NF-κB signaling.

Two hit induced acute lung injury impairs cognitive function in mice: A potential model to study cross talk between lung and brain

Acute lung injury (ALI), a pulmonary inflammatory disorder, is associated with high morbidity and mortality rates. Interestingly, ALI survivors have been reported for some neurocognitive deterioration at/after discharge. However, the molecular factors behind such extra pulmonary manifestation are not clearly known. The present work was designed to investigate lung-brain cross talk in experimental mice for deciphering primary molecular factors that may be involved in ALI-mediated cognitive impairment. ALI was induced in Balb/c mice by intra-tracheal administration of either 0.1 N HCl (2 ml/kg) or LPS (1 mg/kg) as single hits or both agents were administered successively to mimic the 'two hit' model. Interestingly two hit-mediated ALI resulted in exaggerated inflammatory response as reflected by increased pulmonary neutrophils and inflammatory factors (TNF-α/IL-1β/IL-6). Additionally, two hits resulted in delayed resolution of lung inflammation and was coupled with persistent decline in memory, as assessed by Morris water maze test. Further, two hits elevate serum levels of TNF-α/IL-1β which was associated with compromised blood brain barrier (BBB), as evident by decreased expression of occludin/claudin-5 and consequent Evans-blue extravasation in hippocampus 1 week post injury. Finally, dexamethasone protects against the two hit mediated cognitive impairment by lowering the pro-inflammatory factors (TNF-α/IL-1β) both in lungs and blood. Overall, we report for the first time that 'two hit' mediated ALI cause persistent cognitive impairment in mice partly via up-regulating systemic expression of TNF-α/IL-1β that may disrupt BBB and hence the model may be a useful tool to examine the lung-brain cross-talk at the molecular level for exploring newer therapeutics.

Poly(ADP-Ribose)Polymerase-1 in Lung Inflammatory Disorders: A Review

Asthma, acute lung injury (ALI), and chronic obstructive pulmonary disease (COPD) are lung inflammatory disorders with a common outcome, that is, difficulty in breathing. Corticosteroids, a class of potent anti-inflammatory drugs, have shown less success in the treatment/management of these disorders, particularly ALI and COPD; thus, alternative therapies are needed. Poly(ADP-ribose)polymerases (PARPs) are the post-translational modifying enzymes with a primary role in DNA repair. During the last two decades, several studies have reported the critical role played by PARPs in a good of inflammatory disorders. In the current review, the studies that address the role of PARPs in asthma, ALI, and COPD have been discussed. Among the different members of the family, PARP-1 emerges as a key player in the orchestration of lung inflammation in asthma and ALI. In addition, PARP activation seems to be associated with the progression of COPD. Furthermore, PARP-14 seems to play a crucial role in asthma. STAT-6 and GATA-3 are reported to be central players in PARP-1-mediated eosinophilic inflammation in asthma. Interestingly, oxidative stress-PARP-1-NF-κB axis appears to be tightly linked with inflammatory response in all three-lung diseases despite their distinct pathophysiologies. The present review sheds light on PARP-1-regulated factors, which may be common or differential players in asthma/ALI/COPD and put forward our prospective for future studies.

PARP inhibitor, olaparib ameliorates acute lung and kidney injury upon intratracheal administration of LPS in mice

We have previously shown that PARP-1 inhibition provides protection against lung inflammation in the context of asthma and acute lung injury. Olaparib is a potent new generation PARP inhibitor that has been approved for human testing. The present work was designed to evaluate its beneficial potential against LPS-induced acute lung injury and acute kidney injury upon intratracheal administration of the endotoxin in mice. Administration of olaparib at different doses, 30 min after LPS treatment showed that single intraperitoneal injection of the drug at 5 mg/kg b.wt. reduced the total number of inflammatory cells particularly neutrophils in the lungs. This was associated with reduced pulmonary edema as the total protein content in the bronchoalveolar fluid was found to be decreased substantially. Olaparib provided strong protection against LPS-mediated secondary kidney injury as reflected by restoration of serum levels of urea, creatinine, and uric acid toward normal. The drug restored the LPS-mediated redox imbalance toward normal in lung and kidney tissues as assessed by measuring malondialdehyde and GSH levels. Finally, RT-PCR data revealed that olaparib downregulates the LPS-induced expression of NF-κB-dependent genes namely TNF-α, IL-1β, and VCAM-1 in the lungs without altering the expression of total p65NF-κB. Overall, the data suggest that olaparib has a strong potential to protect against LPS-induced lung injury and associated dysfunctioning of kidney in mice. Given the fact that olaparib is approved by FDA for human testing, our findings can pave the way for testing of the drug on humans inflicted with acute lung injury.