Macrophage Depletion Protects against Cigarette Smoke-Induced Inflammatory Response in the Mouse Colon and Lung

Chronic Exposure to Both Electronic and Conventional Cigarettes Alters Ileum and Colon Turnover, Immune Function, and Barrier Integrity in Mice

Although the effects of cigarette smoke (CS) on the development of several intestinal diseases is well documented, the impact of e-cigarette aerosol (e-cig) on digestive health is largely unknown. To compare the effects of e-cig and CS on mouse ileum and colon, animals were chronically exposed for 6 months by nose-only inhalation to e-cig at 18 or 30 W power, or to 3R4F CS. Results showed that e-cig exposure decreased colon cell proliferation. Several other proliferative defects were observed in response to both e-cig and CS exposure, including up- and down-regulation of cyclin D1 protein levels in the ileum and colon, respectively. E-cig and CS exposure reduced myeloperoxidase activity in the ileum. In the colon, both exposures disrupted gene expression of cytokines and T cell transcription factors. For tight junction genes, ZO-1- and occludin-protein expression levels were reduced in the ileum and colon, respectively, by e-cig and CS exposure. The 16S sequencing of microbiota showed specific mild dysbiosis, according to the type of exposure. Overall, e-cig exposure led to altered proliferation, inflammation, and barrier function in both the ileum and colon, and therefore may be a gut hazard on par with conventional CS.

Cigarette smoke-induced dysbiosis: comparative analysis of lung and intestinal microbiomes in COPD mice and patients

BACKGROUND

The impact of cigarette smoke (CS) on lung diseases and the role of microbiome dysbiosis in chronic obstructive pulmonary disease (COPD) have been previously reported; however, the relationships remain unclear.

METHODS

Our research examined the effects of 20-week cigarette smoke (CS) exposure on the lung and intestinal microbiomes in C57BL/6JNarl mice, alongside a comparison with COPD patients' intestinal microbiome data from a public dataset.

RESULTS

The study found that CS exposure significantly decreased forced vital capacity (FVC), thickened airway walls, and induced emphysema. Increased lung damage was observed along with higher lung keratinocyte chemoattractant (KC) levels by CS exposure. Lung microbiome analysis revealed a rise in Actinobacteriota, while intestinal microbiome showed significant diversity changes, indicating dysbiosis. Principal coordinate analysis highlighted distinct intestinal microbiome compositions between control and CS-exposed groups. In the intestinal microbiome, notable decreases in Patescibacteria, Campilobacterota, Defferibacterota, Actinobacteriota, and Desulfobacterota were observed. We also identified correlations between lung function and dysbiosis in both lung and intestinal microbiomes. Lung interleukins, interferon-ɣ, KC, and 8-isoprostane levels were linked to lung microbiome dysbiosis. Notably, dysbiosis patterns in CS-exposed mice were similar to those in COPD patients, particularly of Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage 4 patients. This suggests a systemic impact of CS exposure.

CONCLUSION

In summary, CS exposure induces significant dysbiosis in lung and intestinal microbiomes, correlating with lung function decline and injury. These results align with changes in COPD patients, underscoring the important role of microbiome in smoke-related lung diseases.

Development of finely tuned liposome nanoplatform for macrophage depletion

BACKGROUND

Immunotherapy with clodronate-encapsulated liposomes, which induce macrophage depletion, has been studied extensively. However, previously reported liposomal formulation-based drugs (Clodrosome® and m-Clodrosome®) are limited by their inconsistent size and therapeutic efficacy. Thus, we aimed to achieve consistent therapeutic effects by effectively depleting macrophages with uniform-sized liposomes.

RESULTS

We developed four types of click chemistry-based liposome nanoplatforms that were uniformly sized and encapsulated with clodronate, for effective macrophage depletion, followed by conjugation with Man-N3 and radiolabeling. Functionalization with Man-N3 improves the specific targeting of M2 macrophages, and radioisotope labeling enables in vivo imaging of the liposome nanoplatforms. The functionalized liposome nanoplatforms are stable under physiological conditions. The difference in the biodistribution of the four liposome nanoplatforms in vivo were recorded using positron emission tomography imaging. Among the four platforms, the clodronate-encapsulated mannosylated liposome effectively depleted M2 macrophages in the normal liver and tumor microenvironment ex vivo compared to that by Clodrosome® and m-Clodrosome®.

CONCLUSION

The newly-developed liposome nanoplatform, with finely tuned size control, high in vivo stability, and excellent ex vivo M2 macrophage targeting and depletion effects, is a promising macrophage-depleting agent.

PD-L1 Expression Is Increased in LPS-Induced Acute Respiratory Distress Syndrome by PI3K-AKT-Egr-1/C/EBPδ Signaling Pathway

The role of programmed death ligand 1 (PD-L1) has been extensively investigated in adaptive immune system. However, increasing data show that innate immune responses are also affected by the immune checkpoint molecule. It has been demonstrated that regulation of PD-L1 signaling in macrophages may be a potential therapeutic method for acute respiratory distress syndrome (ARDS). However, the PD-L1 expression pattern in local macrophages and whole lung tissues remains mysterious, hindering optimization of the potential treatment program. Therefore, we aim to determine the PD-L1 expression pattern during ARDS. Our findings show that PD-L1 levels are markedly increased in lipopolysaccharide (LPS)-stimulated lung tissues, which might be attributable to an increase in the gene expression by immune cells, including macrophages and neutrophils. In vitro experiments are performed to explore the mechanism involved in LPS-induced PD-L1 production. We find that PD-L1 generation is controlled by transcription factors early growth response 1 (Egr-1) and CCAAT/enhancer binding protein delta (C/EBPδ). Strikingly, PD-L1 production is enhanced by phosphoinositide-3 kinase (PI3K)-protein kinase B (AKT) signaling pathway via up-regulation of Egr-1 and C/EBPδ expressions. Additionally, we observe that expressions of Egr-1 and C/EBPδ mutually reinforce each other. Moreover, we observe that PD-L1 is protective for ARDS due to its regulatory role in macrophage-associated inflammatory response. In summary, during LPS-induced ARDS, PD-L1 expression, which is beneficial for the disease, is increased via the PI3K-AKT1-Egr-1/C/EBPδ signaling pathway, providing theoretical basis for application of methods controlling PD-L1 signaling in macrophages for ARDS treatment in clinic.

Monocyte-derived alveolar macrophages are key drivers of smoke-induced lung inflammation and tissue remodeling

Smoking is a leading risk factor of chronic obstructive pulmonary disease (COPD), that is characterized by chronic lung inflammation, tissue remodeling and emphysema. Although inflammation is critical to COPD pathogenesis, the cellular and molecular basis underlying smoking-induced lung inflammation and pathology remains unclear. Using murine smoke models and single-cell RNA-sequencing, we show that smoking establishes a self-amplifying inflammatory loop characterized by an influx of molecularly heterogeneous neutrophil subsets and excessive recruitment of monocyte-derived alveolar macrophages (MoAM). In contrast to tissue-resident AM, MoAM are absent in homeostasis and characterized by a pro-inflammatory gene signature. Moreover, MoAM represent 46% of AM in emphysematous mice and express markers causally linked to emphysema. We also demonstrate the presence of pro-inflammatory and tissue remodeling associated MoAM orthologs in humans that are significantly increased in emphysematous COPD patients. Inhibition of the IRAK4 kinase depletes a rare inflammatory neutrophil subset, diminishes MoAM recruitment, and alleviates inflammation in the lung of cigarette smoke-exposed mice. This study extends our understanding of the molecular signaling circuits and cellular dynamics in smoking-induced lung inflammation and pathology, highlights the functional consequence of monocyte and neutrophil recruitment, identifies MoAM as key drivers of the inflammatory process, and supports their contribution to pathological tissue remodeling.

The role of Th17 cells: explanation of relationship between periodontitis and COPD?

Periodontitis and chronic obstructive pulmonary disease (COPD) are chronic inflammatory diseases with common risk factors, such as long-term smoking, age, and social deprivation. Many observational studies have shown that periodontitis and COPD are correlated. Moreover, they share a common pathophysiological process involving local accumulation of inflammatory cells and cytokines and damage of soft tissues. The T helper 17 (Th17) cells and the related cytokines, interleukin (IL)-17, IL-22, IL-1β, IL-6, IL-23, and transforming growth factor (TGF)-β, play a crucial regulatory role during the pathophysiological process. This paper reviewed the essential roles of Th17 lineage in the occurrence of periodontitis and COPD. The gaps in the study of their common pathological mechanism were also evaluated to explore future research directions. Therefore, this review can provide study direction for the association between periodontitis and COPD and new ideas for the clinical diagnosis and treatment of the two diseases.

Verapamil attenuates oxidative stress and inflammatory responses in cigarette smoke (CS)-induced murine models of acute lung injury and CSE-stimulated RAW 264.7 macrophages via inhibiting the NF-κB pathway

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS), severe form of ALI, are characterized by overwhelming of lung inflammation, and no treatment is currently available to treat ALI/ARDS. Cigarette smoke (CS) is one of the prime causes to induce ALI/ARDS via oxidative stress. Despite extensive research, no appropriate therapy is currently available to treat ALI/ARDS. Hence, new potential approaches are needed to treat ALI/ARDS. Consequently, this project was designed to explore the protective effects of verapamil against CS-induced ALI by in vivo and in vitro method. In vivo data obtained from respiratory mechanics, pulmonary morphometric analyses and lung histopathology revealed that verapamil dose-dependently and strikingly decreased the lung weight coefficient, attenuated the albumin exudation into lungs, minimized the infiltration of macrophages and neutrophils into lungs, reduced the pro-inflammatory cytokines (tumour necrosis factor-α (TNF-α), interleukin-6 (IL-6) and keratinocyte chemoattractant (KC)) production, and improved the hypoxemia and lung histopathological changes. Similarly, verapamil also reduced the production of TNF-α, IL-6 and KC from cigarette smoke extract (CSE)-stimulated RAW 264.7 macrophage. Importantly, verapamil dose-dependently and remarkably suppressed the CS-induced oxidative stress via not only reducing the myeloperoxidase (MPO) activity of lungs, total oxidative stress (TOS) and malondialdehyde (MDA) content in the lungs and supernatant of RAW 264.7 macrophage but also improving total antioxidant capacity (TAC) and superoxide dismutase (SOD) production. Finally, verapamil strikingly decreased the NF-κB expression both in in vivo and in vitro models. Hence, verapamil has positive therapeutic effects against CS-induced ALI via suppressing uncontrolled inflammatory response, oxidative stress and NF-κB p65 signaling.

Intraperitoneally Delivered Mesenchymal Stem Cells Alleviate Experimental Colitis Through THBS1-Mediated Induction of IL-10-Competent Regulatory B Cells

Mesenchymal stem cells (MSCs) show promising therapeutic potential in treating inflammatory bowel disease (IBD), and intraperitoneal delivery of MSCs have become a more effective route for IBD treatment. However, the underlying mechanisms are still poorly understood. Here, we found that intraperitoneally delivered MSCs significantly alleviated experimental colitis. Depletion of peritoneal B cells, but not macrophages, clearly impaired the therapeutic effects of MSCs. Intraperitoneally delivered MSCs improved IBD likely by boosting the IL-10-producing B cells in the peritoneal cavity, and a single intraperitoneal injection of MSCs could significantly prevent disease severity in a recurrent mouse colitis model, with lower proinflammation cytokines and high level of IL-10. The gene expression profile revealed that thrombospondin-1 (THBS1) was dramatically upregulated in MSCs after coculture with peritoneal lavage fluid from colitis mice. Knockout of THBS1 expression in MSCs abolished their therapeutic effects in colitis and the induction of IL-10-producing B cells. Mechanistically, THBS1 modulates the activation of transforming growth factor-β (TGF-β), which combines with TGF-β receptors on B cells and contributes to IL-10 production. Blocking the interaction between THBS1 and latent TGF-β or inhibiting TGF-β receptors (TGF-βR) significantly reversed the THBS1-mediated induction of IL-10-producing B cells and the therapeutic effects on colitis. Collectively, our study revealed that intraperitoneally delivered MSCs secreted THBS1 to boost IL-10⁺Bregs and control the progression and recurrence of colitis, providing new insight for the prevention and treatment of IBD.

ISM1 protects lung homeostasis via cell-surface GRP78-mediated alveolar macrophage apoptosis

Alveolar macrophages (AMs) are critical for lung immune defense and homeostasis. They are orchestrators of chronic obstructive pulmonary disease (COPD), with their number significantly increased and functions altered in COPD. However, it is unclear how AM number and function are controlled in a healthy lung and if changes in AMs without environmental assault are sufficient to trigger lung inflammation and COPD. We report here that absence of isthmin 1 (ISM1) in mice (Ism1-/- ) leads to increase in both AM number and functional heterogeneity, with enduring lung inflammation, progressive emphysema, and significant lung function decline, phenotypes similar to human COPD. We reveal that ISM1 is a lung resident anti-inflammatory protein that selectively triggers the apoptosis of AMs that harbor high levels of its receptor cell-surface GRP78 (csGRP78). csGRP78 is present at a heterogeneous level in the AMs of a healthy lung, but csGRP78high AMs are expanded in Ism1-/- mice, cigarette smoke (CS)-induced COPD mice, and human COPD lung, making these cells the prime targets of ISM1-mediated apoptosis. We show that csGRP78high AMs mostly express MMP-12, hence proinflammatory. Intratracheal delivery of recombinant ISM1 (rISM1) depleted csGRP78high AMs in both Ism1-/- and CS-induced COPD mice, blocked emphysema development, and preserved lung function. Consistently, ISM1 expression in human lungs positively correlates with AM apoptosis, suggesting similar function of ISM1-csGRP78 in human lungs. Our findings reveal that AM apoptosis regulation is an important physiological mechanism for maintaining lung homeostasis and demonstrate the potential of pulmonary-delivered rISM1 to target csGRP78 as a therapeutic strategy for COPD.

Epithelial Ablation of Miro1/Rhot1 GTPase Augments Lung Inflammation by Cigarette Smoke

Mitochondrial quality control is sustained by Miro1 (Rhot1), a calcium-binding membrane-anchored GTPase during mitophagy. The exact mechanism that operates the interaction of Miro1 with mitophagy machinery and their role in cigarette smoke (CS)-induced mitochondrial dysfunction that often results in lung inflammation is unclear. We hypothesized that Miro1 plays an important role in regulating mitophagy machinery and the resulting lung inflammation by CS exposure to mice. The lung epithelial Rhot1^fl/fl (WT) and Rhot1^CreCC10 mice were exposed to mainstream CS for 3 days (acute) and 4 months (chronic). Acute CS exposure showed a notable increase in the total inflammatory cells, macrophages, and neutrophils that are associated with inflammatory mediators. Chronic exposure showed increased infiltration of neutrophils versus air controls. The effects of acute and chronic CS exposure were augmented in the Rhot1^CreCC10 group, indicating that epithelial Miro1 ablation led to the augmentation of inflammatory cell infiltration with alteration in the inflammatory mediators. Thus, Rhot1/Miro1 plays an important role in regulating CS-induced lung inflammatory responses with implications in mitochondrial quality control.

Recent trends of NFκB decoy oligodeoxynucleotide-based nanotherapeutics in lung diseases

Nuclear factor κB (NFκB) is a unique protein complex that plays a major role in lung inflammation and respiratory dysfunction. The NFκB signaling pathway, therefore becomes an avenue for the development of potential pharmacological interventions, especially in situations where chronic inflammation is often constitutively active and plays a key role in the pathogenesis and progression of the disease. NFκB decoy oligodeoxynucleotides (ODNs) are double-stranded and carry NFκB binding sequences. They prevent the formation of NFκB-mediated inflammatory cytokines and thus have been employed in the treatment of a variety of chronic inflammatory diseases. However, the systemic administration of naked decoy ODNs restricts their therapeutic effectiveness because of their poor pharmacokinetic profile, instability, degradation by cellular enzymes and their low cellular uptake. Both structural modification and nanotechnology have shown promising results in enhancing the pharmacokinetic profiles of potent therapeutic substances and have also shown great potential in the treatment of respiratory diseases such as asthma, chronic obstructive pulmonary disease and cystic fibrosis. In this review, we examine the contribution of NFκB activation in respiratory diseases and recent advancements in the therapeutic use of decoy ODNs. In addition, we also highlight the limitations and challenges in use of decoy ODNs as therapeutic molecules, cellular uptake of decoy ODNs, and the current need for novel delivery systems to provide efficient delivery of decoy ODNs. Furthermore, this review provides a common platform for discussion on the existence of decoy ODNs, as well as outlining perspectives on the latest generation of delivery systems that encapsulate decoy ODNs and target NFκB in respiratory diseases.

Is sputum cytology reliable for detection of atypical lung epithelial proliferative changes triggered by cigarette smoking?

BACKGROUND

In recent years, Saudi Arabia has witnessed major tobacco smoking-related disease, such as cardiovascular disease and cancer, particularly among the younger population.

METHODOLOGY

The present study aimed at evaluating the effect of cigarette smoke on lung epithelial cells.

RESULTS

This was a cross-sectional case-control study involving 300 apparently healthy volunteers living in Ha'il, Northern Saudi Arabia. Cigarette smokers (N = 100) were used as cases, and non-smokers (N = 200) were used as controls. A sputum specimen was obtained from each participant, employing all necessary safety precautions and sample adequacy measures.

RESULTS

Among 300 study subjects, cytologic atypia was identified in 14/300 (4.7%). Among the 14 cases with atypical cytologic changes, 13/14 (92.9%) were in smokers and 1/14 (7.1%) was in a non-smoker. The risk of lung cytologic atypia associated with cigarette smoking, was OR (95% CI) = 29.73 (3.82-230.87), P = 0.0001. Out of 300 study subjects, metaplasia was identified in 45/300 (15%). Among 45 cases with metaplastic changes, 26/45 (57.8%) were in the smokers and 19/45 (42.2%) were in non-smokers. The risk of lung epithelial metaplasia associated with cigarette smoking was OR (95% CI) = 3.34 (1.74-6.41), P = 0.0003.

CONCLUSION

Cigarette smoking is a significant risk for developing lung epithelial atypia, lung metaplasia, and inflammatory cell infiltrate (especially chronic inflammation). Sputum cytology is a simple, non-invasive method that can be used in screening at-risk populations for early detection of lung proliferative changes associated with tobacco smoking.

Targeting macrophage polarization by Nrf2 agonists for treating various xenobiotics-induced toxic responses

Macrophages can polarize into different phenotypes in response to different microenvironmental stimuli. Macrophage polarization has been assigned to two extreme states, namely proinflammatory M1 and anti-inflammatory M2. Accumulating evidences have demonstrated that M1 polarized macrophages contribute to various toxicants-induced deleterious effects. Switching macrophages from proinflammatory M1 phenotype toward anti-inflammatory M2 phenotype could be a promising approach for treating various inflammatory diseases. Studies in the past few decades have revealed that nuclear factor erythroid 2-related factor 2 (Nrf2) can modulate the polarization of macrophages. Specifically, activation of Nrf2 could block M1 stimuli-induced production of proinflammatory cytokines and chemokines, and shift the polarization of macrophages toward M2 by cross-talking with nuclear factor kappa-B (NF-κB), mitogen-activated protein kinases (MAPKs), peroxisome proliferator-activated receptor γ (PPARγ), and autophagy. Importantly, a great number of studies have confirmed the beneficial effects of natural and synthesized Nrf2 agonists on various inflammatory diseases; however, most of these compounds are far away from clinical application due to lack of characterization and defects of study designs. Interestingly, some endogenous Nrf2 inducers and compounds with dual activities (such as the Nrf2 inducing and CO releasing effects) exhibit potent anti-inflammatory effects, which points out an important direction for future researches.

Intratracheal Ovalbumin Administration Induces Colitis Through the IFN-γ Pathway in Mice

Recent studies have reported an increased incidence of inflammatory bowel disease (IBD) in patients with pulmonary diseases. Despite clinical and epidemiological studies of the interplay between colitis and asthma, the diseases' related underlying mechanisms remain unclear. In this study, we evaluated the development of colitis in a model of allergic airway inflammation. We revealed that intratracheal chronic ovalbumin (OVA) exposure induces colitis and allergic airway inflammation. Interestingly, induction of colitis was largely regulated by Th1, rather than Th2 responses, whereas allergic airway inflammation was primarily mediated by Th2 responses. Experiments in Tbx21 (T-bet) and Ifng (IFN-γ) deficient mice have confirmed that IFN-γ is a major mediator involved in OVA-induced colitis. These findings broaden current understanding of allergen induced colitis pathology and could play a role in the development of novel clinical treatment strategies for asthmatic patients who are at risk of developing colitis.

CRTH2 antagonist, CT‑133, effectively alleviates cigarette smoke-induced acute lung injury

AIMS

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS), characterized by overwhelming lung inflammation, are associated with high mortality. Cigarette smoke (CS) is one of the major causes of ALI/ARDS. Since high expression of prostaglandin (PG) D2 has been observed in CS-induced lung injury. Currently, no effective pharmacological therapies are available to treat ALI, and supportive therapies remain the mainstay of treatment. Therefore, we investigated the protective effect of CT‑133, a newly discovered selective CRTH2 antagonist, on CS-induced ALI in vivo and in vitro.

MAIN METHODS

CT‑133 (10 and 30 mg/kg), dexamethasone (1 mg/kg) and normal saline were intratracheally administrated 1 hr prior to whole-body CS-exposure for seven consecutive days to study the key characteristics of ALI. Subsequently, CSE (4%)- and PGD2-stimulated RAW 264.7 macrophages were used to evaluate the protective effect of CT‑133.

KEY FINDINGS

CT‑133 remarkably attenuated infiltration of inflammatory cells, neutrophils, and macrophages in the BALF, albumin contents, expression of IL‑1β, IL‑6, TNF‑α and KC, lung myeloperoxidase (MPO) activity and lung histopathological alterations caused by CS exposure in mice. Moreover, CT‑133 not only reversed the uncontrolled secretion of IL‑1β, IL-6, TNF‑α and KC from CSE- and PGD2-stimulated RAW 264.7 macrophages but also augmented IL-10 production in both in vivo and in vitro studies. Additionally, CT‑133 alleviated in vitro neutrophil migration chemoattracted by PGD2.

SIGNIFICANCE

Our results provide the first evidence that targeting CRTH2 could be a new potential therapeutic option to treat CS-induced ALI.