Establishment of stable reporter expression for in vivo imaging of nuclear factor-κB activation in mouse liver

Inflammation conditional genome editing mediated by the CRISPR-Cas9 system

The specificity of CRISPR-Cas9 in response to particular pathological stimuli remains largely unexplored. Hence, we designed an inflammation-inducible CRISPR-Cas9 system by grafting a sequence that binds with NF-κB to the CRISPR-Cas9 framework, termed NBS-CRISPR. The genetic scissor function of this developed genome-editing tool is activated on encountering an inflammatory attack and is inactivated or minimized in non-inflammation conditions. Furthermore, we employed this platform to reverse inflammatory conditions by targeting the MyD88 gene, a crucial player in the NF-κB signaling pathway, and achieved impressive therapeutic effects. Finally, during inflammation, P65 (RELA) can translocate to the nucleus from the cytoplasm. Herein, to avoid Cas9 leaky DNA cleavage activity i, we constructed an NBS-P65-CRISPR system expressing the Cas9-p65 fusion protein. Our inflammation inducible Cas9-mediated genome editing strategy provides new perspectives and avenues for pathological gene interrogation.

Stored whole blood transfusion initiates serum amyloid A activation monitored by real-time dynamic imaging

BACKGROUND

Transfusion of stored whole blood (SWB) to resuscitate severe traumatic haemorrhage patients in military operations and civilian emergency centres is being increasingly used in routine practice. It has been well established that transfusion of red blood cells (RBCs) after prolonged storage has harmful effects, mainly mediated by inflammation. Whether the side effects of inflammation are brought about by SWB transfusion remains unclear.

MATERIALS AND METHODS

A hepatocyte SAA (serum amyloid A) specific reporter mouse that facilitated non-invasive imaging of hepatocyte SAA expression was used to evaluate acute inflammation and acute-phase reaction after the transfusion of SWB or components separated from end-storage whole blood. The whole blood of C57BL/6 donor mouse was used to model an allogeneic transfusion to BALB/c recipient mouse.

RESULTS

End-storage whole blood (14 days of storage) transfusion induced the most significant SAA expression, while 10-day storage resulted in a much weaker signal compared to their fresh and 5-day storage counterparts. RBCs rather than white blood cells and plasma-containing platelets are thought to be responsible for the systemic inflammatory and SAA activation during end-storage whole blood transfusion. Circulatory and hepatic pro-inflammatory cytokines secreted by M1-polarised macrophage initiated the SAA expression in hepatocytes through nuclear transcription factor NF-κB.

DISCUSSION

Storage lesions will also occur during the storage of whole blood, which is related to the change in RBCs with prolonged storage. The side effect induced by systemic inflammation and acute-phase reaction should be considered before resuscitation with long-term storage whole blood transfusion.

MARCKS cooperates with NKAP to activate NF-kB signaling in smoke-related lung cancer

Rationale: Cigarette smoking is a major risk factor for lung cancer development and progression; however, the mechanism of how cigarette smoke activates signaling pathways in promoting cancer malignancy remains to be established. Herein, we aimed to determine the contribution of a signaling protein, myristoylated alanine-rich C kinase substrate (MARCKS), in smoke-mediated lung cancer. Methods: We firstly examined the levels of phosphorylated MARCKS (phospho-MARCKS) in smoke-exposed human lung cancer cells and specimens as well as non-human primate airway epithelium. Next, the MARCKS-interactome and its gene networks were identified. We also used genetic and pharmacological approaches to verify the functionality and molecular mechanism of smoke-induced phospho-MARCKS. Results: We observed that MARCKS becomes activated in airway epithelium and lung cancer cells in response to cigarette smoke. Functional proteomics revealed MARCKS protein directly binds to NF-κB-activating protein (NKAP). Following MARCKS phosphorylation at ser159 and ser163, the MARCKS-NKAP interaction was inhibited, leading to the activation of NF-κB signaling. In a screen of two cohorts of lung cancer patients, we confirmed that phospho-MARCKS is positively correlated with phospho-NF-κB (phospho-p65), and poor survival. Surprisingly, smoke-induced phospho-MARCKS upregulated the expression of pro-inflammatory cytokines, epithelial-mesenchymal transition, and stem-like properties. Conversely, targeting of MARCKS phosphorylation with MPS peptide, a specific MARCKS phosphorylation inhibitor, suppressed smoke-mediated NF-κB signaling activity, pro-inflammatory cytokines expression, aggressiveness and stemness of lung cancer cells. Conclusion: Our results suggest that phospho-MARCKS is a novel NF-kB activator in smoke-mediated lung cancer progression and provide a promising molecular model for developing new anticancer strategies.

PTPROt aggravates inflammation by enhancing NF-κB activation in liver macrophages during nonalcoholic steatohepatitis

Rationale: Inflammation plays a crucial role in the progression of nonalcoholic steatohepatitis (NASH). Protein tyrosine phosphatase receptor type O truncated isoform (PTPROt) is an integral membrane protein that has been identified in osteoclasts, macrophages, and B lymphocytes. However, its relationship between inflammation and NASH is largely unknown. Herein, we aimed to study the function of PTPROt in NASH progression.

Methods: We established a NASH mouse model in wild-type (WT), PTPRO knockout mice by western diet (WD) and methionine-choline-deficient diet (MCD). In addition, MCD-induced NASH model was established in BMT mice. Moreover, we determined the expression of PTPROt in liver macrophages in human subjects without steatosis, with simple steatosis, and with NASH to confirm the relationship between PTPROt and NASH. In vitro assays were also performed to study the molecular role of PTPROt in NASH progression.

Results: Human samples and animal model results illustrated that PTPROt is increased in liver macrophages during NASH progression and is positively correlated with the degree of NASH. Our animal model also showed that PTPROt in liver macrophages can enhance the activation of the NF-κB signaling pathway, which induces the transcription of genes involved in the inflammatory response. Moreover, PTPROt promotes the transcription of pro-oxidant genes and inhibits antioxidant and protective genes via increased activation of the NF-κB signaling pathway, thereby causing an increased level of reactive oxygen species (ROS) and damaged mitochondria. This triggers the NLRP3-IL1β axis and causes a heightened inflammatory response. Notably, PTPROt partially limits inflammation and ROS production by promoting mitophagy, which participates in a negative feedback loop in this model.

Conclusions: Our data strongly indicate that PTPROt plays a dual role in inflammation via the NF-κB signaling pathway in liver macrophages during NASH. Further studies are required to explore therapeutic strategies and prevention of this common liver disease through PTPROt.

p300/CBP inhibitor A-485 alleviates acute liver injury by regulating macrophage activation and polarization

High morbidity and mortality are associated with acute liver injury (ALI) for which no effective targeted drugs or pharmacotherapies are available. Discovery of potential therapeutic targets as well as inhibitors that can alleviate ALI is imperative. As excessive inflammatory cytokines released by macrophages are a critical cause of liver injury, we aimed to find novel compounds that could inhibit macrophage expression of inflammatory cytokines and alleviate liver injury.

Methods: A high throughput assay was established to screen a small molecule inhibitor library of epigenetic targets. A highly selective catalytic p300/CBP inhibitor A-485 was identified as a potent hit in vitro and administrated to the lipopolysaccharide (LPS)/D-galactosamine (GalN)-induced mice in vivo. For in vitro analysis, RAW264.7 cells and primary BMDM cells exposed to LPS were co-incubated with A-485. A model of acute liver injury induced by LPS and GalN was used for evaluation of in vivo treatment efficacy.

Results: A-485 inhibited LPS-induced inflammatory cytokine expression in a concentration-dependent manner in vitro. Significantly, A-485 administration alleviated histopathological abnormalities, lowered plasma aminotransferases, and improved the survival rate in the LPS/GalN-stimulated mice. Integrative ChIP-Seq and transcriptome analysis in the ALI animal model and macrophages revealed that A-485 preferentially blocked transcriptional activation of a broad set of pathologic genes enriched in inflammation-related signaling networks. Significant inhibition of H3K27ac/H3K18ac at promoter regions of these pivotal inflammatory genes was observed, in line with their suppressed transcription after A-485 treatment. Reduced expression of these pathological pro-inflammatory genes resulted in a decrease in inflammatory pathway activation, M1 polarization as well as reduced leukocyte infiltration in ALI mouse model, which accounted for the protective effects of A-485 on liver injury.

Conclusion: Using a novel strategy targeting macrophage inflammatory activation and cytokine expression, we established a high-throughput screening assay to discover potential candidates for ALI treatment. We demonstrated that A-485, which targeted pathological inflammatory signaling networks at the level of chromatin, was pharmacologically effective in vivo and in vitro. Our study thus provided a novel target as well as a potential drug candidate for the treatment of liver injury and possibly for other acute inflammatory diseases.

Noninvasive Imaging of Stored Red Blood Cell-Transfusion Aggravating Sepsis-Induced Liver Injury Associated with Increased Activation of M1-Polarized Kupffer Cells

Supplemental Digital Content is available in the text

Liver injury has a critical effect on the severity and outcome of sepsis. The impact of stored red blood cells (RBCs) on the pathogenesis of sepsis-associated hepatic injury is not well understood. Therefore, to investigate the effects of stored-RBC transfusion on sepsis-induced liver damage as well as the associated mechanism, we constructed a sepsis mouse model enabling noninvasive imaging of bacterial infection caused by Pseudomonas aeruginosa, a common gram-negative respiratory pathogen. We showed that transfusions with stored RBCs enhanced sepsis-induced liver injury in vivo, and liver injury exacerbated the severity of sepsis and decreased survival in P aeruginosa-infected mice. Stored-RBC transfusions enhanced the production of proinflammatory cytokines such as tumor necrosis factor (TNF)-α, interleukin 6 (IL-6), and IL-1β, which play important roles in sepsis-associated liver injury in P aeruginosa-infected mice. Further study showed that the enhanced inflammation observed was associated with increased activation of M1-polarized Kupffer cells, which produce many inflammatory cytokines, including TNF-α and IL-6. Moreover, the M1-polarized Kupffer cells and secreted proinflammatory cytokines exerted their effects on hepatocytes through enhanced Jun N-terminal kinase activation and inhibited nuclear factor-kappaB activation, demonstrating that transfusion with stored RBCs disrupted the balance between cell survival and cell death in the liver. Understanding the mechanisms whereby stored RBCs might contribute to these complications will likely be helpful in providing guidance toward making transfusions safer.

Reactive oxygen species-responsive polymeric nanoparticles for alleviating sepsis-induced acute liver injury in mice

Sepsis-associated acute liver injury contributes to the pathogenesis of multiple organ dysfunction syndrome and is associated with increased mortality. Currently, no specific therapeutics for sepsis-associated liver injury are available. With excess levels of reactive oxygen species (ROS) being implicated as key players in sepsis-induced liver injury, we hypothesize that ROS-responsive nanoparticles (NPs) formed via the self-assembly of diblock copolymers of poly(ethylene glycol) (PEG) and poly(propylene sulfide) (PPS) may function as an effective drug delivery system for alleviating sepsis-induced liver injury by preferentially releasing drug molecules at the disease site. However, there are no reports available on the biocompatibility and effect of PEG-b-PPS-NPs in vivo. Herein, this platform was tested for delivering the promising antioxidant therapeutic molecule melatonin (Mel), which currently has limited therapeutic efficacy because of its poor pharmacokinetic properties. The mPEG-b-PPS-NPs efficiently encapsulated Mel using the oil-in-water emulsion technique and provided sustained, on-demand release that was modulated in vitro by the hydrogen peroxide concentration. Animal studies using a mouse model of sepsis-induced acute liver injury revealed that Mel-loaded mPEG-b-PPS-NPs are biocompatible and much more efficacious than an equivalent amount of free drug in attenuating oxidative stress, the inflammatory response, and subsequent liver injury. Accordingly, this work indicates that mPEG-b-PPS-NPs show potential as an ROS-mediated on-demand drug delivery system for improving Mel bioavailability and treating oxidative stress-associated diseases such as sepsis-induced acute liver injury.

Non-Invasive Imaging Serum Amyloid A Activation through the NF-κB Signal Pathway upon Gold Nanostructure Exposure

With the objective of investigating the acute activation of inflammatory cascades upon exposure to gold nanoparticles (GNPs) as well as detailing the mechanisms, a reporter mouse model that allows for non-invasive and longitudinal imaging of hepatic acute-phase serum amyloid A (SAA) activation is constructed. The model is able to visualize SAA activation at the transcriptional stage, with higher sensitivity than serum protein detection by ELISA. GNPs of various sizes (10-80 nm) and geometries are assessed using the reporter mice with results demonstrating that 50 nm nanospheres (GNS50) possess the highest capacity to induce hepatic SAA activation. Detailed analysis uncovers that resident macrophages in the liver are the main origins of these cytokines and that the exposure to GNS50 significantly induces the M1 macrophage phenotype. Moreover, those M1-polarized macrophages, together with the subsequently secreted pro-inflammatory cytokines, exert effects on hepatocytes and then initiate SAA transcription through the NF-κB signal pathway. The results detail the sequential reactions to GNPs among macrophages, inflammatory mediators, and SAA-synthesizing hepatocytes, which shed light on the acute effects of GNPs on the body. In addition, the established in situ and highly sensitive SAA detection system is expected to have vast applications in evaluating NP-induced acute inflammatory reactions.