Regulation of macrophage activation by lactylation in lung disease.

Lactylation is a process where lactate, a cellular metabolism byproduct, is added to proteins, altering their functions. In the realm of macrophage activation, lactylation impacts inflammatory response and immune regulation. Understanding the effects of lactylation on macrophage activation is vital in lung diseases, as abnormal activation and function are pivotal in conditions like pneumonia, pulmonary fibrosis, COPD, and lung cancer. This review explores the concept of lactylation, its regulation of macrophage activation, and recent research progress in lung diseases. It offers new insights into lung disease pathogenesis and potential therapeutic targets.

Breath of fresh air: Investigating the link between AGEs, sRAGE, and lung diseases.

Advanced glycation end products (AGEs) are compounds formed via non-enzymatic reactions between reducing sugars and amino acids or proteins. AGEs can accumulate in various tissues and organs and have been implicated in the development and progression of various diseases, including lung diseases. The receptor of advanced glycation end products (RAGE) is a receptor that can bind to advanced AGEs and induce several cellular processes such as inflammation and oxidative stress. Several studies have shown that both AGEs and RAGE play a role in the pathogenesis of lung diseases, such as chronic obstructive pulmonary disease, asthma, idiopathic pulmonary fibrosis, cystic fibrosis, and acute lung injury. Moreover, the soluble form of the receptor for advanced glycation end products (sRAGE) has demonstrated its ability to function as a decoy receptor, possessing beneficial characteristics such as anti-inflammatory, antioxidant, and anti-fibrotic properties. These qualities make it an encouraging focus for therapeutic intervention in managing pulmonary disorders. This review highlights the current understanding of the roles of AGEs and (s)RAGE in pulmonary diseases and their potential as biomarkers and therapeutic targets for preventing and treating these pathologies.

Cell Proliferation and Apoptosis-Key Players in the Lung Aging Process.

Currently, the global lifespan has increased, resulting in a higher proportion of the population over 65 years. Changes that occur in the lung during aging increase the risk of developing acute and chronic lung diseases, such as acute respiratory distress syndrome, chronic obstructive pulmonary disease, idiopathic pulmonary fibrosis, and lung cancer. During normal tissue homeostasis, cell proliferation and apoptosis create a dynamic balance that constitutes the physiological cell turnover. In basal conditions, the lungs have a low rate of cell turnover compared to other organs. During aging, changes in the rate of cell turnover in the lung are observed. In this work, we review the literature that evaluates the role of molecules involved in cell proliferation and apoptosis in lung aging and in the development of age-related lung diseases. The list of molecules that regulate cell proliferation, apoptosis, or both processes in lung aging includes TNC, FOXM1, DNA-PKcs, MicroRNAs, BCL-W, BCL-XL, TCF21, p16, NOX4, NRF2, MDM4, RPIA, DHEA, and MMP28. However, despite the studies carried out to date, the complete signaling pathways that regulate cell turnover in lung aging are still unknown. More research is needed to understand the changes that lead to the development of age-related lung diseases.

Defective mesenchymal Bmpr1a-mediated BMP signaling causes congenital pulmonary cysts.

Abnormal lung development can cause congenital pulmonary cysts, the mechanisms of which remain largely unknown. Although the cystic lesions are believed to result directly from disrupted airway epithelial cell growth, the extent to which developmental defects in lung mesenchymal cells contribute to abnormal airway epithelial cell growth and subsequent cystic lesions has not been thoroughly examined. In the present study using genetic mouse models, we dissected the roles of bone morphogenetic protein (BMP) receptor 1a (Bmpr1a)-mediated BMP signaling in lung mesenchyme during prenatal lung development and discovered that abrogation of mesenchymal Bmpr1a disrupted normal lung branching morphogenesis, leading to the formation of prenatal pulmonary cystic lesions. Severe deficiency of airway smooth muscle cells and subepithelial elastin fibers were found in the cystic airways of the mesenchymal Bmpr1a knockout lungs. In addition, ectopic mesenchymal expression of BMP ligands and airway epithelial perturbation of the Sox2-Sox9 proximal-distal axis were detected in the mesenchymal Bmpr1a knockout lungs. However, deletion of Smad1/5, two major BMP signaling downstream effectors, from the lung mesenchyme did not phenocopy the cystic abnormalities observed in the mesenchymal Bmpr1a knockout lungs, suggesting that a Smad-independent mechanism contributes to prenatal pulmonary cystic lesions. These findings reveal for the first time the role of mesenchymal BMP signaling in lung development and a potential pathogenic mechanism underlying congenital pulmonary cysts.

Congenital disorders are medical conditions that are present from birth. Although many congenital disorders are rare, they can have a severe impact on the quality of life of those affected. For example, congenital pulmonary airway malformation (CPAM) is a rare congenital disorder that occurs in around 1 out of every 25,000 pregnancies. In CPAM, abnormal, fluid-filled sac-like pockets of tissue, known as cysts, form within the lungs of unborn babies. After birth, these cysts become air-filled and do not behave like normal lung tissue and stop a baby's lungs from working properly. In severe cases, babies with CPAM need surgery immediately after birth. We still do not understand exactly what the underlying causes of CPAM might be. CPAM is not considered to be hereditary ­ that is, it does not appear to be passed down in families ­ nor is it obviously linked to any environmental factors. CPAM is also very difficult to study, because researchers cannot access tissue samples during the critical early stages of the disease. To overcome these difficulties, Luo et al. wanted to find a way to study CPAM in the laboratory. First, they developed a non-human animal 'model' that naturally forms CPAM-like lung cysts, using genetically modified mice where the gene for the signaling molecule Bmpr1a had been deleted in lung cells. Normally, Bmpr1a is part of a set of the molecular instructions, collectively termed BMP signaling, which guide healthy lung development early in life. However, mouse embryos lacking Bmpr1a developed abnormal lung cysts that were similar to those found in CPAM patients, suggesting that problems with BMP signalling might also trigger CPAM in humans. Luo et al. also identified several other genes in the Bmpr1a-deficient mouse lungs that had abnormal patterns of activity. All these genes were known to be controlled by BMP signaling, and to play a role in the development and organisation of lung tissue. This suggests that when these genes are not controlled properly, they could drive formation of CPAM cysts when BMP signaling is compromised. This work is a significant advance in the tools available to study CPAM. Luo et al.'s results also shed new light on the molecular mechanisms underpinning this rare disorder. In the future, Luo et al. hope this knowledge will help us develop better treatments for CPAM, or even help to prevent it altogether.

Lipid-Laden Macrophages in Pulmonary Diseases.

Pulmonary surfactants play a crucial role in managing lung lipid metabolism, and dysregulation of this process is evident in various lung diseases. Alternations in lipid metabolism lead to pulmonary surfactant damage, resulting in hyperlipidemia in response to lung injury. Lung macrophages are responsible for recycling damaged lipid droplets to maintain lipid homeostasis. The inflammatory response triggered by external stimuli such as cigarette smoke, bleomycin, and bacteria can interfere with this process, resulting in the formation of lipid-laden macrophages (LLMs), also known as foamy macrophages. Recent studies have highlighted the potential significance of LLM formation in a range of pulmonary diseases. Furthermore, growing evidence suggests that LLMs are present in patients suffering from various pulmonary conditions. In this review, we summarize the essential metabolic and signaling pathways driving the LLM formation in chronic obstructive pulmonary disease, pulmonary fibrosis, tuberculosis, and acute lung injury.

Emerging Roles of Galectin-3 in Pulmonary Diseases.

Galectin-3 is a multifunctional protein that is involved in various physiological and pathological events. Emerging evidence suggests that galectin-3 also plays a critical role in the pathogenesis of pulmonary diseases. Galectin-3 can be produced and secreted by various cell types in the lungs, and the overexpression of galectin-3 has been found in acute lung injury/acute respiratory distress syndrome (ALI/ARDS), pulmonary hypertension (PH), pulmonary fibrosis diseases, lung cancer, lung infection, chronic obstructive pulmonary disease (COPD), and asthma. Galectin-3 exerts diverse effects on the inflammatory response, immune cell activation, fibrosis and tissue remodeling, and tumorigenesis in these pulmonary disorders, and genetic and pharmacologic modulation of galectin-3 has therapeutic effects on the treatment of pulmonary illnesses. In this review, we summarize the structure and function of galectin-3 and the underlying mechanisms of galectin-3 in pulmonary disease pathologies; we also discuss preclinical and clinical evidence regarding the therapeutic potential of galectin-3 inhibitors in these pulmonary disorders. Additionally, targeting galectin-3 may be a very promising therapeutic approach for the treatment of pulmonary diseases.

AP-1-dependent fibrosis: Exploring its potential role in the pathogenesis of placental transmogrification of the lung (PTL) via tissue-level transcriptome analysis.

Placental transmogrification of the lung (PTL) is a rare pulmonary condition characterized by the presence of immature placental villous structures. The etiology and molecular mechanisms underlying this disease remain largely unknown. This functional study aimed to identify the molecular signatures in the pathogenesis of PTL via comprehensive transcriptome analysis. Comparative transcriptomic assessment of PTL tissue and stromal cells showed differential expression of 257 genes in PTL tissue and 189 genes in stromal cells. Notably, several transcription factors and regulators, including FOSB, FOS, JUN, and ATF3, were upregulated in PTL tissue. Additionally, genes associated with the extracellular matrix and connective tissue, such as COL1A1, MMP2, and SPARC, were significantly altered, indicating possible fibrotic changes. Gene set enrichment analysis highlighted the role of vascular development and extracellular matrix organization, and the Activator Protein-1 (AP-1) transcription factor was significantly activated in PTL tissue. Furthermore, the analysis highlighted an overlap of 25 genes between PTL tissue and stromal cells, underscoring the importance of shared molecular pathways in the pathogenesis of PTL. Among the shared genes, JUND, COL4A2, COL6A2, IGFBP5, and IGFBP7 were consistently upregulated, highlighting the possible involvement of AP-1-mediated signaling and fibrotic changes in the pathogenesis of PTL. The present findings pave the way for further research into the molecular mechanisms underlying PTL and offer novel insights for therapeutic interventions. Given the rarity of PTL, these molecular findings represent a significant step forward in our understanding this enigmatic disease.

[Research progress of PD-L1 in inflammatory lung diseases].

Programmed death-ligand 1 (PD-L1) is important in maintaining central and peripheral immune tolerance in normal tissues, mediating tumor immune escape and keeping the balance between anti- and pro-inflammatory responses. Inflammation plays an important role in inflammatory lung diseases. This article reviews the research progress and potential clinical value of PD-L1 in inflammatory lung diseases, including acute lung injury, chronic obstructive pulmonary disease, asthma and idiopathic pulmonary fibrosis.

Olfactory receptors impact pathophysiological processes of lung diseases in bronchial epithelial cells.

BACKGROUND: Therapeutic options for steroid-resistant non-type 2 inflammation in obstructive lung diseases are limited. Bronchial epithelial cells are key in the pathogenesis by releasing the central proinflammatory cytokine interleukine-8 (IL-8). Olfactory receptors (ORs) are expressed in various cell types. This study examined the drug target potential of ORs by investigating their impact on associated pathophysiological processes in lung epithelial cells. METHODS: Experiments were performed in the A549 cell line and in primary human bronchial epithelial cells. OR expression was investigated using RT-PCR, Western blot, and immunocytochemical staining. OR-mediated effects were analyzed by measuring 1) intracellular calcium concentration via calcium imaging, 2) cAMP concentration by luminescence-based assays, 3) wound healing by scratch assays, 4) proliferation by MTS-based assays, 5) cellular vitality by Annexin V/PI-based FACS staining, and 6) the secretion of IL-8 in culture supernatants by ELISA. RESULTS: By screening 100 potential OR agonists, we identified two, Brahmanol and Cinnamaldehyde, that increased intracellular calcium concentrations. The mRNA and proteins of the corresponding receptors OR2AT4 and OR2J3 were detected. Stimulation of OR2J3 with Cinnamaldehyde reduced 1) IL-8 in the absence and presence of bacterial and viral pathogen-associated molecular patterns (PAMPs), 2) proliferation, and 3) wound healing but increased cAMP. In contrast, stimulation of OR2AT4 by Brahmanol increased wound healing but did not affect cAMP and proliferation. Both ORs did not influence cell vitality. CONCLUSION: ORs might be promising drug target candidates for lung diseases with non-type 2 inflammation. Their stimulation might reduce inflammation or prevent tissue remodeling by promoting wound healing.

Targeting transitioning lung monocytes/macrophages as treatment strategies in lung disease related to environmental exposures.

BACKGROUND: Environmental/occupational exposures cause significant lung diseases. Agricultural organic dust extracts (ODE) and bacterial component lipopolysaccharide (LPS) induce recruited, transitioning murine lung monocytes/macrophages, yet their cellular role remains unclear. METHODS: CCR2 RFP+ mice were intratracheally instilled with high concentration ODE (25%), LPS (10 µg), or gram-positive peptidoglycan (PGN, 100 µg) for monocyte/macrophage cell-trafficking studies. CCR2 knockout (KO) mice and administration of intravenous clodronate liposomes strategies were employed to reduce circulating monocytes available for lung recruitment following LPS exposure. Lung tissues and bronchoalveolar lavage fluid (BALF) were collected. Pro-inflammatory and/or pro-fibrotic cytokines, chemokines, and lung extracellular matrix mediators were quantitated by ELISA. Infiltrating lung cells including monocyte/macrophage subpopulations, neutrophils, and lymphocytes were characterized by flow cytometry. Lung histopathology, collagen content, vimentin, and post-translational protein citrullination and malondialdehyde acetaldehyde (MAA) modification were quantitated. Parametric statistical tests (one-way ANOVA, Tukey'smultiple comparison) and nonparametric statistical (Kruskal-Wallis, Dunn's multiple comparison) tests were used following Shapiro-Wilk testing for normality. RESULTS: Intratracheal instillation of ODE, LPS, or PGN robustly induced the recruitment of inflammatory CCR2+ CD11cintCD11bhi monocytes/macrophages and both CCR2+ and CCR2- CD11c-CD11bhi monocytes at 48 h. There were also increases in CCR2+ CD4+ and CD8+ T cells and NK cells. Despite reductions in LPS-induced lung infiltrating CD11cintCD11bhi cells (54% reduction), CCR2 knockout (KO) mice were not protected against LPS-induced inflammatory and pro-fibrotic consequences. Instead, compensatory increases in lung neutrophils and CCL2 and CCL7 release occurred. In contrast, the depletion of circulating monocytes through the administration of intravenous clodronate (vs. vehicle) liposomes 24 h prior to LPS exposure reduced LPS-induced infiltrating CD11cintCD11bhi monocyte-macrophage subpopulation by 59% without compensatory changes in other cell populations. Clodronate liposome pre-treatment significantly reduced LPS-induced IL-6 (66% reduction), matrix metalloproteinases (MMP)-3 (36%), MMP-8 (57%), tissue inhibitor of metalloproteinases (61%), fibronectin (38%), collagen content (22%), and vimentin (40%). LPS-induced lung protein citrullination and MAA modification, post-translational modifications implicated in lung disease, were reduced (39% and 48%) with clodronate vs. vehicle liposome. CONCLUSION: Highly concentrated environmental/occupational exposures induced the recruitment of CCR2+ and CCR2- transitioning monocyte-macrophage and monocyte subpopulations and targeting peripheral monocytes may reduce the adverse lung consequences resulting from exposures to LPS-enriched inhalants.

Application of Metabolomics across the Spectrum of Pulmonary and Critical Care Medicine.

In recent years, metabolomics, the systematic study of small-molecule metabolites in biological samples, has yielded fresh insights into the molecular determinants of pulmonary diseases and critical illness. The purpose of this article is to orient the reader to this emerging field by discussing the fundamental tenets underlying metabolomics research, the tools and techniques that serve as foundational methodologies, and the various statistical approaches to analysis of metabolomics datasets. We present several examples of metabolomics applied to pulmonary and critical care medicine to illustrate the potential of this avenue of research to deepen our understanding of pathophysiology. We conclude by reviewing recent advances in the field and future research directions that stand to further the goal of personalizing medicine to improve patient care.

SIRT1: An Intermediator of Key Pathways Regulating Pulmonary Diseases.

Silent information regulator type-1 (SIRT1), a nicotinamide adenine dinucleotide+-dependent deacetylase, is a member of the sirtuins family and has unique protein deacetylase activity. SIRT1 participates in physiological as well as pathophysiological processes by targeting a wide range of protein substrates and signalings. In this review, we described the latest progress of SIRT1 in pulmonary diseases. We have introduced the basic information and summarized the prominent role of SIRT1 in several lung diseases, such as acute lung injury, acute respiratory distress syndrome, chronic obstructive pulmonary disease, lung cancer, and aging-related diseases.

The Dual Role of Chemerin in Lung Diseases.

Chemerin is an atypical chemokine first described as a chemoattractant agent for monocytes, natural killer cells, plasmacytoid and myeloid dendritic cells, through interaction with its main receptor, the G protein-coupled receptor chemokine-like receptor 1 (CMKLR1). Chemerin has been studied in various lung disease models, showing both pro- and anti-inflammatory properties. Given the incidence and burden of inflammatory lung diseases from diverse origins (infectious, autoimmune, age-related, etc.), chemerin has emerged as an interesting therapeutical target due to its immunomodulatory role. However, as highlighted by this review, further research efforts to elucidate the mechanisms governing chemerin's dual pro- and anti-inflammatory characteristics are urgently needed. Moreover, although a growing body of evidence suggests chemerin as a potential biomarker for the diagnosis and/or prognosis of inflammatory lung diseases, this review underscores the necessity for standardizing both sampling types and measurement techniques before drawing definitive conclusions.

Dysregulation of CITED2 in abnormal lung development in the nitrofen rat model.

PURPOSE: CITED2 both modulates lung, heart and diaphragm development. The role of CITED2 in the pathogenesis of congenital diaphragmatic hernia (CDH) is unknown. We aimed to study CITED2 during abnormal lung development in the nitrofen model. METHODS: Timed-pregnant rats were given nitrofen on embryonic day (E) 9 to induce CDH. Fetal lungs were harvested on E15, 18 and 21. We performed RT-qPCR, RNAscope™ in situ hybridization and immunofluorescence staining for CITED2. RESULTS: We observed no difference in RT-qPCR (control: 1.09 ± 0.22 and nitrofen: 0.95 ± 0.18, p = 0.64) and in situ hybridization (1.03 ± 0.03; 1.04 ± 0.03, p = 0.97) for CITED2 expression in E15 nitrofen and control pups. At E18, CITED2 expression was reduced in in situ hybridization of nitrofen lungs (1.47 ± 0.05; 1.14 ± 0.07, p = 0.0006), but not altered in RT-qPCR (1.04 ± 0.16; 0.81 ± 0.13, p = 0.33). In E21 nitrofen lungs, CITED2 RNA expression was increased in RT-qPCR (1.04 ± 0.11; 1.52 ± 0.17, p = 0.03) and in situ hybridization (1.08 ± 0.07, 1.29 ± 0.04, p = 0.02). CITED2 protein abundance was higher in immunofluorescence staining of E21 nitrofen lungs (2.96 × 109 ± 0.13 × 109; 4.82 × 109 ± 0.25 × 109, p < 0.0001). CONCLUSION: Our data suggest that dysregulation of CITED2 contributes to abnormal lung development of CDH, as demonstrated by the distinct spatial-temporal distribution in nitrofen-induced lungs.

Extracellular Matrix as a Driver of Chronic Lung Diseases.

The extracellular matrix (ECM) is not just a three-dimensional scaffold that provides stable support for all cells in the lungs, but also an important component of chronic fibrotic airway, vascular, and interstitial diseases. It is a bioactive entity that is dynamically modulated during tissue homeostasis and disease, that controls structural and immune cell functions and drug responses, and that can release fragments that have biological activity and that can be used to monitor disease activity. There is a growing recognition of the importance of considering ECM changes in chronic airway, vascular, and interstitial diseases, including 1) compositional changes, 2) structural and organizational changes, and 3) mechanical changes and how these affect disease pathogenesis. As altered ECM biology is an important component of many lung diseases, disease models must incorporate this factor to fully recapitulate disease-driver pathways and to study potential novel therapeutic interventions. Although novel models are evolving that capture some or all of the elements of the altered ECM microenvironment in lung diseases, opportunities exist to more fully understand cell-ECM interactions that will help devise future therapeutic targets to restore function in chronic lung diseases. In this perspective article, we review evolving knowledge about the ECM's role in homeostasis and disease in the lung.

Roles of extracellular matrix in lung diseases.

Extracellular matrix (ECM) is a non-cellular constituent found in all tissues and organs. Although ECM was previously recognized as a mere "molecular glue" that supports the tissue structure of organs such as the lungs, it has recently been reported that ECM has important biological activities for tissue morphogenesis, inflammation, wound healing, and tumor progression. Proteoglycans are the main constituent of ECM, with growing evidence that proteoglycans and their associated glycosaminoglycans play important roles in the pathogenesis of several diseases. However, their roles in the lungs are incompletely understood. Leukocyte migration into the lung is one of the main aspects involved in the pathogenesis of several lung diseases. Glycosaminoglycans bind to chemokines and their interaction fine-tunes leukocyte migration into the affected organs. This review focuses on the role chemokine and glycosaminoglycan interactions in neutrophil migration into the lung. Furthermore, this review presents the role of proteoglycans such as syndecan, versican, and hyaluronan in inflammatory and fibrotic lung diseases.

Exploring the mechanism of lung injury induced by lunar dust simulant in rats based on metabolomic analysis.

Inflammatory response and oxidative stress are considered to be important mechanisms of lung injury induced by lunar dust. However, the pulmonary toxicological mechanism remains unclear. In the present study, Wistar rats were exposed to CLDS-i 7 days/week, 4 h/day, for 4 weeks in the mouth and nose. Lung tissue samples were collected for histopathological analysis and ultra-performance liquid chromatography-mass spectrometry analysis. Enzyme activities and expression levels of key metabolic enzymes were detected by biochemical analysis and real-time PCR. The pathological features of lung tissue showed that CLDS-i caused congestion and inflammation in the lungs, and the lung structure was severely damaged. Metabolomics analysis showed that 141 metabolites were significantly changed in the lung tissue of the CLDS-i group compared with the control group. Combined with Kegg pathway analysis, it was found that the changes of amino acid metabolites were involved in these pathways, indicating that the simulated lunar dust exposure had the most obvious effect on amino acid metabolism in the lung tissue of rats. Real-time PCR analysis showed that the mRNA expression of six key enzymes related to amino acid metabolism was changed, and the enzyme activities of these key enzymes were also changed, which were consistent with the results of qPCR. These results suggest that changes in amino acid metabolism may be closely related to the pathogenesis of lung injury induced by lunar dust, and amino acid metabolism may be a potential biomarker of lung diseases related to lunar dust exposure.

Mesenchymal stem cell-derived exosomes as delivery vehicles for non-coding RNAs in lung diseases.

The burden of lung diseases is gradually increasing with an increase in the average human life expectancy. Therefore, it is necessary to identify effective methods to treat lung diseases and reduce their social burden. Currently, an increasing number of studies focus on the role of mesenchymal stem cell-derived exosomes (MSC-Exos) as a cell-free therapy in lung diseases. They show great potential for application to lung diseases as a more stable and safer option than traditional cell therapies. MSC-Exos are rich in various substances, including proteins, nucleic acids, and DNA. Delivery of Non-coding RNAs (ncRNAs) enables MSC-Exos to communicate with target cells. MSC-Exos significantly inhibit inflammatory factors, reduce oxidative stress, promote normal lung cell proliferation, and reduce apoptosis by delivering ncRNAs. Moreover, MSC-Exos carrying specific ncRNAs affect the proliferation, invasion, and migration of lung cancer cells, thereby playing a role in managing lung cancer. The detailed mechanisms of MSC-Exos in the clinical treatment of lung disease were explored by developing standardized culture, isolation, purification, and administration strategies. In summary, MSC-Exo-based delivery methods have important application prospects for treating lung diseases.

Metabolic pathways in immune senescence and inflammaging: Novel therapeutic strategy for chronic inflammatory lung diseases. An EAACI position paper from the Task Force for Immunopharmacology.

The accumulation of senescent cells drives inflammaging and increases morbidity of chronic inflammatory lung diseases. Immune responses are built upon dynamic changes in cell metabolism that supply energy and substrates for cell proliferation, differentiation, and activation. Metabolic changes imposed by environmental stress and inflammation on immune cells and tissue microenvironment are thus chiefly involved in the pathophysiology of allergic and other immune-driven diseases. Altered cell metabolism is also a hallmark of cell senescence, a condition characterized by loss of proliferative activity in cells that remain metabolically active. Accelerated senescence can be triggered by acute or chronic stress and inflammatory responses. In contrast, replicative senescence occurs as part of the physiological aging process and has protective roles in cancer surveillance and wound healing. Importantly, cell senescence can also change or hamper response to diverse therapeutic treatments. Understanding the metabolic pathways of senescence in immune and structural cells is therefore critical to detect, prevent, or revert detrimental aspects of senescence-related immunopathology, by developing specific diagnostics and targeted therapies. In this paper, we review the main changes and metabolic alterations occurring in senescent immune cells (macrophages, B cells, T cells). Subsequently, we present the metabolic footprints described in translational studies in patients with chronic asthma and chronic obstructive pulmonary disease (COPD), and review the ongoing preclinical studies and clinical trials of therapeutic approaches aiming at targeting metabolic pathways to antagonize pathological senescence. Because this is a recently emerging field in allergy and clinical immunology, a better understanding of the metabolic profile of the complex landscape of cell senescence is needed. The progress achieved so far is already providing opportunities for new therapies, as well as for strategies aimed at disease prevention and supporting healthy aging.

Inhaled RNA drugs to treat lung diseases: Disease-related cells and nano-bio interactions.

In recent years, RNA-based therapies have gained much attention as biomedicines due to their remarkable therapeutic effects with high specificity and potency. Lung diseases offer a variety of currently undruggable but attractive targets that could potentially be treated with RNA drugs. Inhaled RNA drugs for the treatment of lung diseases, including asthma, chronic obstructive pulmonary disease, cystic fibrosis, and acute respiratory distress syndrome, have attracted more and more attention. A variety of novel nanoformulations have been designed and attempted for the delivery of RNA drugs to the lung via inhalation. However, the delivery of RNA drugs via inhalation poses several challenges. It includes protection of the stability of RNA molecules, overcoming biological barriers such as mucus and cell membrane to the delivery of RNA molecules to the targeted cytoplasm, escaping endosomal entrapment, and circumventing unwanted immune response etc. To address these challenges, ongoing researches focus on developing innovative nanoparticles to enhance the stability of RNA molecules, improve cellular targeting, enhance cellular uptake and endosomal escape to achieve precise delivery of RNA drugs to the intended lung cells while avoiding unwanted nano-bio interactions and off-target effects. The present review first addresses the pathologic hallmarks of different lung diseases, disease-related cell types in the lung, and promising therapeutic targets in these lung cells. Subsequently we highlight the importance of the nano-bio interactions in the lung that need to be addressed to realize disease-related cell-specific delivery of inhaled RNA drugs. This is followed by a review on the physical and chemical characteristics of inhaled nanoformulations that influence the nano-bio interactions with a focus on surface functionalization. Finally, the challenges in the development of inhaled nanomedicines and some key aspects that need to be considered in the development of future inhaled RNA drugs are discussed.