An Inhaled Inhibitor of Myristoylated Alanine-Rich C Kinase Substrate Reverses LPS-Induced Acute Lung Injury in Mice

MARCKS Inhibition Alters Bovine Neutrophil Responses to Salmonella Typhimurium

Neutrophils are innate immune cells that respond quickly to sites of bacterial infection and play an essential role in host defense. Interestingly, some bacterial pathogens benefit from exuberant neutrophil inflammation. Salmonella is one such pathogen that can utilize the toxic mediators released by neutrophils to colonize the intestine and cause enterocolitis. Because neutrophils can aid gut colonization during Salmonella infection, neutrophils represent a potential host-directed therapeutic target. Myristoylated alanine-rich C-kinase substrate (MARCKS) is an actin-binding protein that plays an essential role in many neutrophil effector responses. We hypothesized that inhibition of MARCKS protein would alter bovine neutrophil responses to Salmonella Typhimurium (STm) ex vivo. We used a MARCKS inhibitor peptide to investigate the role of MARCKS in neutrophil responses to STm. This study demonstrates that MARCKS inhibition attenuated STm-induced neutrophil adhesion and chemotaxis. Interestingly, MARCKS inhibition also enhanced neutrophil phagocytosis and respiratory burst in response to STm. This is the first report describing the role of MARCKS protein in neutrophil antibacterial responses.

Progression of Acute Lung Injury in Intratracheal LPS Rat Model: Efficacy of Fluticasone, Dexamethasone, and Pirfenidone

INTRODUCTION

We investigated the potential of LPS (10-300 µg/rat) administered intratracheally (i.t.) to induce reproducible features of acute lung injury (ALI) and compared the pharmacological efficacy of anti-inflammatory glucocorticoids and antifibrotic drugs to reduce the disease. Additionally, we studied the time-dependent progression of ALI in this LPS rat model.

METHODS

We conducted (1) dose effect studies of LPS administered i.t. at 10, 30, 100, and 300 μg/rat on ALI at 4 h timepoint; (2) pharmacological interventions using i.t. fluticasone (100 and 300 μg/rat), i.t. pirfenidone (4,000 μg/rat), and peroral dexamethasone (1 mg/kg) at 4 h timepoint; (3) kinetic studies at 0, 2, 4, 6, 8, 10, and 24 h post-LPS challenge. Phenotype or pharmacological efficacy was assessed using predetermined ALI features such as pulmonary inflammation, edema, and inflammatory mediators.

RESULTS

All LPS doses induced a similar increase of inflammation, edema, and inflammatory mediators, e.g., IL6, IL1β, TNFα, and CINC-1. In pharmacological intervention studies, we showed fluticasone and dexamethasone ameliorated ALI by inhibiting inflammation (>60-80%), edema (>70-100%), and the increase of cytokines IL6, IL1β, and TNFα (≥70-90%). We also noticed some inhibition of CINC-1 (25-35%) and TIMP1 (57%) increase with fluticasone and dexamethasone. Conversely, pirfenidone failed to inhibit inflammation, edema, and mediators of inflammation. Last, in ALI kinetic studies, we observed progressive pulmonary inflammation and TIMP1 levels, which peaked at 6 h and remained elevated up to 24 h. Progressive pulmonary edema started between 2 and 4 h and was sustained at later timepoints. On average, levels of IL6 (peak at 6-8 h), IL1β (peak at 2-10 h), TNFα (peak at 2 h), CINC-1 (peak at 2-6 h), and TGFβ1 (peak at 8 h) were elevated between 2 and 10 h and declined toward 24 h post-LPS challenge.

CONCLUSION

Our data show that 10 μg/rat LPS achieved a robust, profound, and reproducible experimental ALI phenotype. Glucocorticoids ameliorated key ALI features at the 4-h timepoint, but the antifibrotic pirfenidone failed. Progressive inflammation and sustained pulmonary edema were present up to 24 h, whereas levels of inflammatory mediators were dynamic during ALI progression. This study's data might be helpful in designing appropriate experiments to test the potential of new therapeutics to cure ALI.

Myristoylated, alanine-rich C-kinase substrate (MARCKS) regulates toll-like receptor 4 signaling in macrophages

MARCKS (myristoylated alanine-rich C-kinase substrate) is a membrane-associated protein expressed in many cell types, including macrophages. MARCKS is functionally implicated in cell adhesion, phagocytosis, and inflammation. LPS (lipopolysaccharide) triggers inflammation via TLR4 (toll-like receptor 4).The presence of MARCKS and the formation of phospho-MARCKS in various cell types have been described, but the role(s) of MARCKS in regulating macrophage functions remain unclear. We investigated the role of MARCKS in inflammation. Confocal microscopy revealed that MARCKS and phospho-MARCKS increased localization to endosomes and the Golgi apparatus upon LPS stimulation.CRISPR-CAS9 mediated knockout of MARCKS in macrophages downregulated the production of TNF and IL6, suggesting a role for MARCKS in inflammatory responses. Our comprehensive proteomics analysis together with real-time metabolic assays comparing LPS-stimulation of WT and MARCKS knock-out macrophages provided insights into the involvement of MARCKS in specific biological processes including innate immune response, inflammatory response, cytokine production, and molecular functions such as extracellularly ATP-gated cation channel activity, electron transfer activity and oxidoreductase activity, uncovering specific proteins involved in regulating MARCKS activity upon LPS stimulation. MARCKS appears to be a key regulator of inflammation whose inhibition might be beneficial for therapeutic intervention in inflammatory diseases.

Aerosolized miR-138-5p and miR-200c targets PD-L1 for lung cancer prevention

The development of chemopreventive strategies with the ability to prevent the progression of lung lesions to malignant cancers would reduce the mortality and morbidity resulting from this deadly disease. Delivery of microRNA (miRNA) by inhalation is a novel method for lung cancer prevention. In this study, we investigated the combined efficacy of aerosolized miR-138-5p and miR-200c miRNA mimics in lung cancer prevention. Combination of the two miRNAs inhibited Benzo(a)pyrene (B((a))P)-induced lung adenomas and N-nitroso-tris-chloroethylurea (NTCU)-induced lung squamous cell carcinomas with no detectable side effects. Using single-cell RNA sequencing (scRNA-seq) and imaging mass cytometry (IMC), we found that both miRNAs inhibited programmed cell death ligand 1 (PD-L1) expression. Our flow cytometry results showed that aerosolized delivery of combined miRNAs increased CD4+ and CD8+ T cells and reduced the expression of programmed cell death protein 1 (PD-1) and T-regulatory cells. Our results demonstrated that the delivery of aerosolized microRNAs targeting PD-L1 can be highly effective in preventing lung cancer development and progression in mice.

Patent landscape highlighting therapeutic implications of peptides targeting myristoylated alanine-rich protein kinase-C substrate (MARCKS)

INTRODUCTION

MARCKS protein, a protein kinase C (PKC) substrate, is known to be at the intersection of several intracellular signaling pathways and plays a pivotal role in cellular physiology. Unlike PKC inhibitors, MARCKS-targeting drug (BIO-11006) has shown early success in clinical trials involving lung diseases. Recent research investigations have identified two MARCKS-targeting peptides which possess multifaceted implications against asthma, cancer, inflammation, and lung diseases.

AREAS COVERED

This review article provides the patent landscape and recent developments on peptides targeting MARCKS for therapeutic purposes. Online free open-access databases were used to fetch out the patent information, and research articles were fetched using PubMed.

EXPERT OPINION

Research studies highlighting the intriguing role of MARCKS in human disease and physiology have dramatically increased in recent years. A similar increasing trend in the number of patents has also been observed related to the MARCKS-targeting peptides. Thus, there is a need to amalgamate and translate such a trend into therapeutic intervention. Our review article provides an overview of such recent advances, and we believe that our compilation will fetch the interest of researchers around the globe to develop MARCKS-targeting peptides in future for human diseases.

Early diagnostic imaging of pneumonia with an ultra-sensitive two-photon near-infrared fluorescent probe

The mortality rate of pneumonia increases significantly with the prolongation of illness. In the pursuit of a tool to accurately diagnose pneumonia in its early stages, we designed and synthesized a two-photon near-infrared fluorescent probe (DCQN) to identify increased concentrations of the inflammation marker SO₂. The probe was found to specifically react with SO₂ by undergoing a 1,4-addition reaction to generate near-infrared fluorescence with good sensitivity (6 s), a large Stokes shift (110 nm) and low detection limit (1.49 nM). DCQN has near-infrared emission as well as good two-photon performance, which can image exogenous and endogenous SO₂ in cells and avoid interference from background fluorescence from cells. Furthermore, this study achieved accurate imaging of a pneumonia lesion site in deep tissues to provide a tool for the fluorescence diagnostic imaging of pneumonia in situ.

Plant-derived bioactive compounds regulate the NLRP3 inflammasome to treat NAFLD

Non-alcoholic fatty liver disease (NAFLD) is a liver disorder characterized by abnormal accumulation of hepatic fat and inflammatory response with complex pathogenesis. Over activation of the pyrin domain-containing protein 3 (NLRP3) inflammasome triggers the secretion of interleukin (IL)-1β and IL-18, induces pyroptosis, and promotes the release of a large number of pro-inflammatory proteins. All of which contribute to the development of NAFLD. There is a great deal of evidence indicating that plant-derived active ingredients are effective and safe for NAFLD management. This review aims to summarize the research progress of 31 active plant-derived components (terpenoids, flavonoids, alkaloids, and phenols) that alleviate lipid deposition, inflammation, and pyroptosis by acting on the NLRP3 inflammasome studied in both in vitro and in vivo NAFLD models. These studies confirmed that the NLRP3 inflammasome and its related genes play a key role in NAFLD amelioration, providing a starting point for further study on the correlation of plant-derived compounds treatment with the NLRP3 inflammasome and NAFLD.

Peptide Inhibitors of MARCKS Suppress Endotoxin Induced Uveitis in Rats

Purpose: To determine if inhibition of Myristoylated Alanine Rich C Kinase Substrate (MARCKS) protein, using novel MARCKS inhibitor peptides, will reduce the severity of endotoxin-induced uveitis (EIU) in rats. Methods: EIU was induced in Lewis rats using subcutaneous administration of lipopolysaccharide. In the first phase of the study, 3 different novel MARCKS inhibitor peptides that mimic the N-terminal region of MARCKS (BIO-11006, or lower molecular weight analogs BIO-91201 or BIO-91202; Biomarck Pharmaceuticals, Ltd., Newtown, PA) were administered intravitreally (IVT) at 50 and 100 μM. In the second phase, BIO-91201 was administered IVT at 10, 50, and 100 μM and topically at the 100 μM concentration. The efficacy of MARCKS inhibitor peptides was assessed by clinical examination using slit lamp biomicroscopy, optical coherence tomography (OCT) anterior chamber cell counts, histopathology, and aqueous humor cytokine analysis. Results: Clinical scores were significantly reduced 24 h following uveitis induction in the first phase of the study in the following treatment groups: BIO-11006 50 μM IVT and 100 μM IVT, BIO-91201 50 μM IVT, and BIO-91202 100 μM IVT (P < 0.05). OCT anterior chamber cell counts were significantly reduced in the first phase of the study in all treatment groups (P < 0.001). OCT anterior chamber cell counts and histopathology scores were significantly reduced in the second phase of the study in the BIO-91201 50 μM IVT group (P < 0.05). No effect was seen with topical administration. Conclusion: MARCKS inhibitor peptides were effective in reducing the severity of ocular inflammation and cellular influx in EIU.

Pulmonary Aerosol Delivery of Let-7b microRNA Confers a Striking Inhibitory Effect on Lung Carcinogenesis through Targeting the Tumor Immune Microenvironment

MicroRNAs are potential candidates for lung cancer prevention and therapy. A major limitation is the lack of an efficient delivery system to directly deliver miRNA to cancer cells while limiting systemic exposure. The delivery of miRNA via inhalation is a potential strategy for lung cancer prevention in high-risk individuals. In this study, the authors investigate the efficacy of aerosolized let-7b miRNA treatment in lung cancer prevention. Let-7b shows significant inhibition of B[a]P-induced lung adenoma with no detectable side effects. Single-cell RNA sequencing of tumor-infiltrating T cells from primary tumors reveals that Let-7b post-transcriptionally suppresses PD-L1 and PD-1 expression in the tumor microenvironment, suggesting that let-7b miRNAs may promote antitumor immunity in vivo. Let-7b treatment decreases the expression of PD-1 in CD8+ T cells and reduces PD-L1 expression in lung tumor cells. The results suggest that this aerosolized let-7b mimic is a promising approach for lung cancer prevention, and that the in vivo tumor inhibitory effects of let-7b are mediated, at least in part, by immune-promoting effects via downregulating PD-L1 in tumors and/or PD-1 on CD8+ T cells. These changes potentiate antitumor CD8+ T cell immune responses, and ultimately lead to tumor inhibition.

Vanillin protects lipopolysaccharide-induced acute lung injury by inhibiting ERK1/2, p38 and NF-κB pathway

Aim: Thus far, the anti-inflammatory effect of vanillin in acute lung injury (ALI) has not been studied. This study aimed to investigate the effect of vanillin in lipopolysaccharide (LPS)-induced ALI. Results & methodology: Our study detected the anti-inflammatory effects of vanillin by ELISA and western blot, respectively. Pretreatment of mice with vanillin significantly attenuated LPS-stimulated lung histopathological changes, myeloperoxidase activity and expression levels of proinflammatory cytokines by inhibiting the phosphorylation activities of ERK1/2, p38, AKT and NF-κB p65. In addition, vanillin inhibited LPS-induced TNF-α and IL-6 expression in RAW264.7 cells via ERK1/2, p38 and NF-κB signaling. Conclusion: Vanillin can inhibit macrophage activation and lung inflammation, which suggests new insights for clinical treatment of ALI.

MARCKS and Lung Disease

MARCKS (myristoylated alanine-rich C kinase substrate) is a prominent PKC substrate expressed in all eukaryotic cells. It is known to bind to and cross-link actin filaments, to serve as a bridge between Ca²⁺/calmodulin and PKC signaling, and to sequester the signaling molecule phosphatidylinositol 4,5-bisphosphate in the plasma membrane. Since the mid-1980s, this evolutionarily conserved and ubiquitously expressed protein has been associated with regulating cellular events that require dynamic actin reorganization, including cellular adhesion, migration, and exocytosis. More recently, translational studies have implicated MARCKS in the pathophysiology of a number of airway diseases, including chronic obstructive pulmonary disease, asthma, lung cancer, and acute lung injury/acute respiratory distress syndrome. This article summarizes the structure and cellular function of MARCKS (also including MARCKS family proteins and MARCKSL1 [MARCKS-like protein 1]). Evidence for MARCKS's role in several lung diseases is discussed, as are the technological innovations that took MARCKS-targeting strategies from theoretical to therapeutic. Descriptions and updates derived from ongoing clinical trials that are investigating inhalation of a MARCKS-targeting peptide as therapy for patients with chronic bronchitis, lung cancer, and ARDS are provided.

A Peptide Inhibitor of NADPH Oxidase (NOX2) Activation Markedly Decreases Mouse Lung Injury and Mortality Following Administration of Lipopolysaccharide (LPS)

We have previously derived three related peptides, based on a nine-amino acid sequence in human or rat/mouse surfactant protein A, that inhibit the phospholipase A₂ activity of peroxiredoxin 6 (Prdx6) and prevent the activation of lung NADPH oxidase (type 2). The present study evaluated the effect of these Prdx6-inhibitory peptides (PIP) in a mouse (C57Bl/6) model of acute lung injury following lipopolysaccharide (LPS) administration. All three peptides (PIP-1, 2 and 3) similarly inhibited the production of reactive O₂ species (ROS) in isolated mouse lungs as detected by the oxidation of Amplex red. PIP-2 inhibited both the increased phospholipase A₂ activity of Prdx6 and lung reactive oxygen species (ROS) production following treatment of mice with intratracheal LPS (5 µg/g body wt.). Pre-treatment of mice with PIP-2 prevented LPS-mediated lung injury while treatment with PIP-2 at 12 or 16 h after LPS administration led to reversal of lung injury when evaluated 12 or 8 h later, respectively. With a higher dose of LPS (15 µg/g body wt.), mortality was 100% at 48 h in untreated mice but only 28% in mice that were treated at 12-24 h intervals, with PIP-2 beginning at 12 h after LPS administration. Treatment with PIP-2 also markedly decreased mortality after intraperitoneal LPS (15 µg/g body wt.), used as a model of sepsis. This study shows the dramatic effectiveness of a peptide inhibitor of Prdx6 against lung injury and mouse mortality in LPS models. We propose that the PIP nonapeptides may be a useful modality to prevent or to treat human ALI.

Prenatal maternal vaginal inflammation increases anxiety and alters HPA axis signalling in adult male mice

BACKGROUND

Maternal infection during pregnancy is known to adversely affect foetal development, but previous studies have rarely investigated the impact of gynaecological diseases during pregnancy on offspring during adulthood. Vaginitis is one of the most prevalent gynaecological diseases during pregnancy.

METHODS

The effect of maternal vaginal inflammation on offspring was simulated by inducing maternal vaginal infection. We performed a transvaginal injection of lipopolysaccharide (LPS) in pregnant mice to induce vaginitis and investigated their offspring by means of behavioural tests and molecular and cellular measurements.

RESULTS

Behavioural tests revealed that the offspring of mothers transvaginally injected with LPS exhibited sex-dependent differences. Male offspring showed increased anxiety-related behaviours, including reduced time exploring the open arm in the elevated plus maze test and light chamber in the light-dark box test. Serum levels of corticosterone were increased in LPS male offspring, indicating activation of the hypothalamic-pituitary-adrenal (HPA) axis. Corticotropin-releasing hormone (CRH) protein expression and c-Fos positive cells were increased in the hypothalamic paraventricular nucleus (PVN) in LPS male offspring, which presented with an increased number of microglia.

CONCLUSION

This study suggests that prenatal vaginal infection increases anxiety-like behaviour in male offspring, possibly via activation of the HPA axis.