Antigen Presentation in the Lung

Activation and maturation of antigen-specific B cells in nonectopic lung infiltrates are independent of germinal center reactions in the draining lymph node

Pulmonary T and B cells are important for protection of this mucosal barrier site. While viral infections lead to the development of ectopic lymphoid structures highly similar to those in germinal centers in secondary lymphoid organs, little is known about how T/B cooperation occurs in the unstructured, diffuse tissue infiltrates characteristic of autoimmune diseases and nonviral infections. Using a mouse model of interstitial lung inflammation, we found that naive B cells are directly activated in lung tissue. Despite the absence of any germinal center-like structures, the interaction of B cells with peripheral T helper cells results in efficient somatic hypermutation and class switching. As antigen-presenting cells, macrophages are critical for this process. Unique B-cell repertoires indicated that the lung response was autonomous from the lung-draining lymph node. Only lung GC-like B cells were switched to IgA and had a broader repertoire, making them ideal candidates for producing broadly neutralizing immunoglobulins against respiratory pathogens.

Research progress on monocyte/macrophage in the development of gastric cancer

Gastric cancer (GC) is diagnosed more than one million times each year and represents a major cause of cancer-related death worldwide. Although GC presents as a group of different types of disease, chronic inflammation has been strongly associated with tumorigenesis. Monocyte/macrophage play important roles in the development of inflammation and are vital components of the tumor microenvironment (TME). Monocyte/macrophage exert protumor and/or antitumor effects through the release of angiogenic and lymphangiogenic factors. Furthermore, tumor associated macrophages (TAMs) are emerging as key players in GC development. It is necessary to review and elucidate the roles of TAM subsets in GC and their molecular features. In this study, we focused on GC-related subsets of monocytes/macrophages and analyzed signaling related to TAMs in GC as well as the potential roles of these cells as therapeutic targets.

Mast cells are key mediators in the pulmonary inflammatory response to formaldehyde exposure

Formaldehyde (FA) is a common chemical linked to respiratory problems such as airway hyperresponsiveness and pulmonary inflammation. Due to its toxicological effects and ease of mass production, FA is also recognized as a significant chemical threat by the U.S. Department of Homeland Security. This study investigates the role of mast cells in the pulmonary inflammatory response to acute high-dose FA exposure. Using wild-type (C57BL/6J) and mast cell-deficient (KitW-sh) mouse models, we assessed the impact of oropharyngeal aspiration of FA on lung pathology. Our findings reveal that C57BL/6J mice experienced significant increases in cellular infiltration, altered immune cell populations, and changes in lipid mediator profiles. In contrast, KitW-sh mice exhibited significantly reduced inflammatory responses. Notably, the presence of mast cells was associated with enhanced dendritic cell migration and differential production of bioactive lipid mediators, such as specialized pro-resolving mediators and pro-inflammatory leukotrienes in C57BL/6J mice. These results highlight the crucial role of mast cells in the immune response to FA and suggest they could be therapeutic targets for treating FA-induced lung inflammation.

T cell interactions with microglia in immune-inflammatory processes of ischemic stroke

The primary mechanism of secondary injury after cerebral ischemia may be the brain inflammation that emerges after an ischemic stroke, which promotes neuronal death and inhibits nerve tissue regeneration. As the first immune cells to be activated after an ischemic stroke, microglia play an important immunomodulatory role in the progression of the condition. After an ischemic stroke, peripheral blood immune cells (mainly T cells) are recruited to the central nervous system by chemokines secreted by immune cells in the brain, where they interact with central nervous system cells (mainly microglia) to trigger a secondary neuroimmune response. This review summarizes the interactions between T cells and microglia in the immune-inflammatory processes of ischemic stroke. We found that, during ischemic stroke, T cells and microglia demonstrate a more pronounced synergistic effect. Th1, Th17, and M1 microglia can co-secrete pro-inflammatory factors, such as interferon-γ, tumor necrosis factor-α, and interleukin-1β, to promote neuroinflammation and exacerbate brain injury. Th2, Treg, and M2 microglia jointly secrete anti-inflammatory factors, such as interleukin-4, interleukin-10, and transforming growth factor-β, to inhibit the progression of neuroinflammation, as well as growth factors such as brain-derived neurotrophic factor to promote nerve regeneration and repair brain injury. Immune interactions between microglia and T cells influence the direction of the subsequent neuroinflammation, which in turn determines the prognosis of ischemic stroke patients. Clinical trials have been conducted on the ways to modulate the interactions between T cells and microglia toward anti-inflammatory communication using the immunosuppressant fingolimod or overdosing with Treg cells to promote neural tissue repair and reduce the damage caused by ischemic stroke. However, such studies have been relatively infrequent, and clinical experience is still insufficient. In summary, in ischemic stroke, T cell subsets and activated microglia act synergistically to regulate inflammatory progression, mainly by secreting inflammatory factors. In the future, a key research direction for ischemic stroke treatment could be rooted in the enhancement of anti-inflammatory factor secretion by promoting the generation of Th2 and Treg cells, along with the activation of M2-type microglia. These approaches may alleviate neuroinflammation and facilitate the repair of neural tissues.

Cell Population-resolved Multiomics Atlas of the Developing Lung

The lung is a vital organ that undergoes extensive morphological and functional changes during postnatal development. To disambiguate how different cell populations contribute to organ development, we performed proteomic and transcriptomic analyses of four sorted cell populations from the lung of human subjects 0-8 years of age with a focus on early life. The cell populations analyzed included epithelial, endothelial, mesenchymal, and immune cells. Our results revealed distinct molecular signatures for each of the sorted cell populations that enable the description of molecular shifts occurring in these populations during postnatal development. We confirmed that the proteome of the different cell populations was distinct regardless of age and identified functions specific to each population. We identified a series of cell population protein markers, including those located at the cell surface, that show differential expression and distribution on RNA in situ hybridization and immunofluorescence imaging. We validated the spatial distribution of alveolar type 1 and endothelial cell surface markers. Temporal analyses of the proteomes of the four populations revealed processes modulated during postnatal development and clarified the findings obtained from whole-tissue proteome studies. Finally, the proteome was compared with a transcriptomics survey performed on the same lung samples to evaluate processes under post-transcriptional control.

Extracellular Vesicles in Asthma: Intercellular Cross-Talk in TH2 Inflammation

Asthma is a complex, multifactorial inflammatory disorder of the airways, characterized by recurrent symptoms and variable airflow obstruction. So far, two main asthma endotypes have been identified, type 2 (T2)-high or T2-low, based on the underlying immunological mechanisms. Recently, extracellular vesicles (EVs), particularly exosomes, have gained increasing attention due to their pivotal role in intercellular communication and distal signaling modulation. In the context of asthma pathobiology, an increasing amount of experimental evidence suggests that EVs secreted by eosinophils, mast cells, dendritic cells, T cells, neutrophils, macrophages, and epithelial cells contribute to disease modulation. This review explores the role of EVs in profiling the molecular signatures of T2-high and T2-low asthma, offering novel perspectives on disease mechanisms and potential therapeutic targets.

CXCL16 knockout inhibit asthma airway inflammation by suppressing H2-DM molecular mediated antigen presentation

The inflammatory microenvironment influences dendritic cell-mediated antigen presentation to regulate asthma Th2 inflammation. The scavenger receptor is expressed on DCs and regulates antigen presentation and T priming. However, whether the transmembrane scavenger receptor (SR-PSOX/CXCL16) regulates the phenotype and antigen presentation function of DCs remains unclear. We found that CXCL16 is mainly expressed on DCs in the lung tissues of asthma patients and asthma mice. CXCL16 knockout led to the suppression of airway inflammation, mucus overproduction, and airway hyperresponsiveness in Aspergillus-induced asthma. In addition, the adoptive transfer of Aspergillus-pulsed DCs shows the CXCL16+ DCs exerted a promoting role in airway inflammation, the CXCL16- DCs inhibit airway inflammation. Additionally, RNA sequencing and flow cytometry data revealed that CXCL16 knockout inhibits airway inflammation by suppressing the antigen processing and presentation function of DCs, which was mediated by MHC II chaperone H2-DM. Furthermore, we found CXCL16 knockout suppressed dendritic cells differentiated forward to cDC2b subtype which is mainly charged with antigen presentation to T cell. In conclusion, we found that CXCL16 downregulated the capacity of DC antigen processing and presentation to suppress airway inflammation by reducing H2-DM expression which mediated DC differentiation. The study suggested that inhibition of CXCL16 can be a potential therapy for asthma.

Proteomic, metabolomic and lipidomic profiles in community acquired pneumonia for differentiating viral and bacterial infections

Community-acquired pneumonia (CAP) has a significant impact on public health, especially in light of the recent SARS-CoV-2 pandemic. To enhance disease characterization and improve understanding of the underlying mechanisms, a comprehensive analysis of the plasma lipidome, metabolome and proteome was conducted in patients with viral and bacterial CAP infections, including those induced by SARS-CoV-2. Lipidomic, metabolomic and proteomic profiling were conducted on plasma samples of 69 patients suffering either from viral or bacterial CAP. Lipid and metabolite analyses were LC-MS-based, while proteomic analyses were performed using multiple panels of the Olink platform. Statistical methods, machine learning and pathway analyses were conducted investigating differences between the infection types. Through comparison of the bacterial and viral pathogen groups, distinct signatures were observed in the plasma profiles. Notably, linoleic acid-derived inflammation signaling metabolites (EpOME and DiHOME) were increased in viral CAP compared to bacterial CAP. Similarly, proteins involved in cellular immune response and apoptosis (LAG-3 and TRAIL) showed elevated levels in viral CAP, while bacterial CAP exhibited notable elevation in pattern-recognizing receptors (CLEC4D and EN-RAGE). Additionally, within the lipidomic profile at baseline, several lipids displayed notable differences between viral and bacterial pneumonia, including bile acids (GCA, TCA, TCDCA), various tri- and diglycerides (TGs and DGs), and several phosphatidylcholines (PCs). These findings hold promise for facilitating the differential diagnosis of viral and bacterial pulmonary infections based on the systemic lipidome, metabolome and proteome, enabling timely treatment decisions. Additionally, they highlight potential targets for drug research, advancing therapeutic interventions in CAP. By providing valuable insights into the molecular characterization of CAP, this study contributes to the improvement of understanding the disease and, ultimately, the development of effective treatment strategies.

MMPred: a tool to predict peptide mimicry events in MHC class II recognition

We present MMPred, a software tool that integrates epitope prediction and sequence alignment algorithms to streamline the computational analysis of molecular mimicry events in autoimmune diseases. Starting with two protein or peptide sets (e.g., from human and SARS-CoV-2), MMPred facilitates the generation, investigation, and testing of mimicry hypotheses by providing epitope predictions specifically for MHC class II alleles, which are frequently implicated in autoimmunity. However, the tool is easily extendable to MHC class I predictions by incorporating pre-trained models from CNN-PepPred and NetMHCpan. To evaluate MMPred's ability to produce biologically meaningful insights, we conducted a comprehensive assessment involving i) predicting associations between known HLA class II human autoepitopes and microbial-peptide mimicry, ii) interpreting these predictions within a systems biology framework to identify potential functional links between the predicted autoantigens and pathophysiological pathways related to autoimmune diseases, and iii) analyzing illustrative cases in the context of SARS-CoV-2 infection and autoimmunity. MMPred code and user guide are made freely available at https://github.com/ComputBiol-IBB/MMPRED.

Time-resolved scRNA-seq reveals transcription dynamics of polarized macrophages with influenza A virus infection and antigen presentation to T cells

Throughout history, the influenza A virus has caused numerous devastating global pandemics. Macrophages, as pivotal innate immune cells, exhibit a wide range of immune functions characterized by distinct polarization states, reflecting their intricate heterogeneity. In this study, we employed the time-resolved single-cell sequencing technique coupled with metabolic RNA labelling to elucidate the dynamic transcriptional changes in distinct polarized states of bone marrow-derived macrophages (BMDMs) upon infection with the influenza A virus. Our approach not only captures the temporal dimension of transcriptional activity, which is lacking in conventional scRNA-seq methods, but also reveals that M2-polarized Arg1_macrophage cluster is the sole state supporting successful replication of influenza A virus. Furthermore, we identified distinct antigen presentation capabilities to CD4+ T and CD8+ T cells across diverse polarized states of macrophages. Notably, the M1 phenotype, exhibited by (BMDMs) and murine alveolar macrophages (AMs), demonstrated superior conventional and cross-presentation abilities for exogenous antigens, with a particular emphasis on cross-presentation capacity. Additionally, as CD8+ T cell differentiation progressed, M1 polarization exhibited an enhanced capacity for cross-presentation. All three phenotypes of BMDMs, including M1, demonstrated robust presentation to CD4+ regulatory T cells, while displaying limited ability to present to naive CD4+ T cells. These findings offer novel insights into the immunological regulatory mechanisms governing distinct polarized states of macrophages, particularly their roles in restricting the replication of influenza A virus and modulating antigen-specific T cell responses through innate immunity.

Combating Emerging Respiratory Viruses: Lessons and Future Antiviral Strategies

Emerging viral diseases, including seasonal illnesses and pandemics, pose significant global public health risks. Respiratory viruses, particularly coronaviruses and influenza viruses, are associated with high morbidity and mortality, imposing substantial socioeconomic burdens. This review focuses on the current landscape of respiratory viruses, particularly influenza and SARS-CoV-2, and their antiviral treatments. It also discusses the potential for pandemics and the development of new antiviral vaccines and therapies, drawing lessons from past outbreaks to inform future strategies for managing viral threats.

B cell dysregulation and depletion therapy in primary membranous nephropathy: Prospects and potential challenges

B cells are crucial to the humoral immune response, originating in the bone marrow and maturing in the spleen and lymph nodes. They primarily function to protect against a wide range of infections through the secretion of antibodies. The role of B cells in primary membranous nephropathy (PMN) has gained significant attention, especially following the discovery of various autoantibodies that target podocyte antigens and the observed positive outcomes from B cell depletion therapy. Increasing evidence points to the presence of abnormal B cell subsets and functions in MN. B cells have varied roles during the different stages of disease onset, progression, and relapse. Initially, B cells facilitate self-antigen presentation, activate effector T cells, and initiate cellular immunity. Subsequently, the disruption of both central and peripheral immune tolerance results in the emergence of autoreactive B cells, with strong germinal center responses as a major source of MN autoantibodies. Additionally, critical B cell subsets, including Bregs, memory B cells, and plasma cells, play roles in the immune dysregulation observed in MN, assisting in predicting disease recurrence and guiding management strategies for MN. This review offers a detailed overview of research advancements on B cells and elucidates their pathological roles in MN.

Modulating macrophage-mediated programmed cell removal: An attractive strategy for cancer therapy

Macrophage-mediated programmed cell removal (PrCR) is crucial for the identification and elimination of needless cells that maintain tissue homeostasis. The efficacy of PrCR depends on the balance between pro-phagocytic "eat me" signals and anti-phagocytic "don't eat me" signals. Recently, a growing number of studies have shown that tumourigenesis and progression are closely associated with PrCR. In the tumour microenvironment, PrCR activated by the "eat me" signal is counterbalanced by the "don't eat me" signal of CD47/SIRPα, resulting in tumour immune escape. Therefore, targeting exciting "eat me" signalling while simultaneously suppressing "don't eat me" signalling and eventually inducing macrophages to produce effective PrCR will be a very attractive antitumour strategy. Here, we comprehensively review the functions of PrCR-activating signal molecules (CRT, PS, Annexin1, SLAMF7) and PrCR-inhibiting signal molecules (CD47/SIRPα, MHC-I/LILRB1, CD24/Siglec-10, SLAMF3, SLAMF4, PD-1/PD-L1, CD31, GD2, VCAM1), the interactions between these molecules, and Warburg effect. In addition, we highlight the molecular regulatory mechanisms that affect immune system function by exciting or suppressing PrCR. Finally, we review the research advances in tumour therapy by activating PrCR and discuss the challenges and potential solutions to smooth the way for tumour treatment strategies that target PrCR.

Advances in Dendritic-Cell-Based Vaccines against Respiratory Fungal Infections

Ever since the discovery of dendritic cells by Ralph Steinman and Zanvil Cohn in 1973, it is increasingly evident that dendritic cells are integral for adaptive immune responses, and there is an undeniable focus on them for vaccines development. Fungal infections, often thought to be innocuous, are becoming significant threats due to an increased immunocompromised or immune-suppressed population and climate change. Further, the recent COVID-19 pandemic unraveled the wrath of fungal infections and devastating outcomes. Invasive fungal infections cause significant case fatality rates ranging from 20% to 90%. Regrettably, no licensed fungal vaccines exist, and there is an urgent need for preventive and therapeutic purposes. In this review, we discuss the ontogeny, subsets, tissue distribution, and functions of lung dendritic cells. In the latter part, we summarize and discuss the studies on the DC-based vaccines against pulmonary fungal infections. Finally, we highlight some emerging potential avenues that can be incorporated for DC-based vaccines against fungal infections.

Single-cell combined with transcriptome sequencing to explore the molecular mechanism of cell communication in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a common, chronic, and progressive lung disease that severely impacts human health and survival. However, the intricate molecular underpinnings of IPF remains elusive. This study aims to delve into the nuanced molecular interplay of cellular interactions in IPF, thereby laying the groundwork for innovative therapeutic approaches in the clinical field of IPF. Sophisticated bioinformatics methods were employed to identify crucial biomarkers essential for the progression of IPF. The GSE122960 single-cell dataset was obtained from the Gene Expression Omnibus (GEO) compendium, and intercellular communication potentialities were scrutinized via CellChat. The random survival forest paradigm was established using the GSE70866 dataset. Quintessential genes were selected through Kaplan-Meier (KM) curves, while immune infiltration examinations, functional enrichment critiques and nomogram paradigms were inaugurated. Analysis of intercellular communication revealed an intimate potential connections between macrophages and various cell types, pinpointing five cardinal genes influencing the trajectory and prognosis of IPF. The nomogram paradigm, sculpted from these seminal genes, exhibits superior predictive prowess. Our research meticulously identified five critical genes, confirming their intimate association with the prognosis, immune infiltration and transcriptional governance of IPF. Interestingly, we discerned these genes' engagement with the EPITHELIAL_MESENCHYMAL_TRANSITION signalling pathway, which may enhance our understanding of the molecular complexity of IPF.

Effects of Combustible Cigarettes and Electronic Nicotine Delivery Systems on the Development and Progression of Chronic Lung Inflammation in Mice

INTRODUCTION

Although detrimental effects of combustible cigarettes (CCs) on the progression of lung inflammatory diseases are well known, changes in electronic nicotine delivery systems (ENDS)-exposed lung-infiltrated immune cells are still unrevealed.

AIMS AND METHODS

The analysis of blood gas parameters, descriptive and quantitative histology of lung tissues, determination of serum cytokines, intracellular staining, and flow cytometry analysis of lung-infiltrated immune cells were used to determine the differences in the extent of lung injury and inflammation between mice from experimental (CC and ENDS-exposed animals) and control groups (Air-exposed mice).

RESULTS

Continuous exposition to either CCs or ENDS induced severe systemic inflammatory response, increased activation of NLRP3 inflammasome in neutrophils and macrophages and enhanced dendritic cell-dependent activation of Th1 and Th17 cells in the lungs. ENDS induced less severe immune response than CCs. Serum concentrations of inflammatory cytokines were significantly lower in the samples of ENDS-exposed mice. Compared to CCs, ENDS recruited lower number of circulating leukocytes in injured lungs and had less capacity to induce CD14/TLR2-dependent activation of NLRP3 inflammasome in lung-infiltrated neutrophils and macrophages. ENDS-primed dendritic cells had reduced capacity for the generation of Th1 and Th17 cell-driven lung inflammation. Accordingly, extensive immune cell-driven lung injury resulted in severe respiratory dysfunction in CCs-exposed mice, while ENDS caused moderate respiratory dysfunction in experimental animals.

CONCLUSIONS

Continuous exposition to either CCs or ENDS induced immune cell-driven lung damage in mice. ENDS triggered immune response, which was less potent than inflammatory response elicited by CCs and, therefore, caused less severe lung injury and inflammation.

IMPLICATIONS

This is the first study that compared the effects of CCs and ENDS on lung-infiltrated immune cells. Although both CCs and ENDS elicited systemic inflammatory response, immune cell-driven lung injury and inflammation were less severe in ENDS-exposed than in CC-exposed animals. Continuous exposition to ENDS-sourced aerosols was less harmful for respiratory function of experimental animals than CC-derived smoke.

Recent Findings on Therapeutic Cancer Vaccines: An Updated Review

Cancer remains one of the global leading causes of death and various vaccines have been developed over the years against it, including cell-based, nucleic acid-based, and viral-based cancer vaccines. Although many vaccines have been effective in in vivo and clinical studies and some have been FDA-approved, there are major limitations to overcome: (1) developing one universal vaccine for a specific cancer is difficult, as tumors with different antigens are different for different individuals, (2) the tumor antigens may be similar to the body's own antigens, and (3) there is the possibility of cancer recurrence. Therefore, developing personalized cancer vaccines with the ability to distinguish between the tumor and the body's antigens is indispensable. This paper provides a comprehensive review of different types of cancer vaccines and highlights important factors necessary for developing efficient cancer vaccines. Moreover, the application of other technologies in cancer therapy is discussed. Finally, several insights and conclusions are presented, such as the possibility of using cold plasma and cancer stem cells in developing future cancer vaccines, to tackle the major limitations in the cancer vaccine developmental process.

Novel inhalation therapy in pulmonary fibrosis: principles, applications and prospects

Pulmonary fibrosis (PF) threatens millions of people worldwide with its irreversible progression. Although the underlying pathogenesis of PF is not fully understood, there is evidence to suggest that the disease can be blocked at various stages. Inhalation therapy has been applied for lung diseases such as asthma and chronic obstructive pulmonary disease, and its application for treating PF is currently under consideration. New techniques in inhalation therapy, such as the application of microparticles and nanoparticles, traditional Chinese medicine monomers, gene therapy, inhibitors, or agonists of signaling pathways, extracellular vesicle interventions, and other specific drugs, are effective in treating PF. However, the safety and effectiveness of these therapeutic techniques are influenced by the properties of inhaled particles, biological and pathological barriers, and the type of inhalation device used. This review provides a comprehensive overview of the pharmacological, pharmaceutical, technical, preclinical, and clinical experimental aspects of novel inhalation therapy for treating PF and focus on therapeutic methods that significantly improve existing technologies or expand the range of drugs that can be administered via inhalation. Although inhalation therapy for PF has some limitations, the advantages are significant, and further research and innovation about new inhalation techniques and drugs are encouraged.

Single-cell resolution of human airway epithelial cells exposed to bronchiolitis obliterans-associated chemicals

Bronchiolitis obliterans (BO) is a fibrotic lung disease characterized by progressive luminal narrowing and obliteration of the small airways. In the nontransplant population, inhalation exposure to certain chemicals is associated with BO; however, the mechanisms contributing to disease induction remain poorly understood. This study's objective was to use single-cell RNA sequencing for the identification of transcriptomic signatures common to primary human airway epithelial cells after chemical exposure to BO-associated chemicals-diacetyl or nitrogen mustard-to help explain BO induction. Primary airway epithelial cells were cultured at air-liquid interface and exposed to diacetyl, nitrogen mustard, or control vapors. Cultures were dissociated and sequenced for single-cell RNA. Differential gene expression and functional pathway analyses were compared across exposures. In total, 75,663 single cells were captured and sequenced from all exposure conditions. Unbiased clustering identified 11 discrete phenotypes, including 5 basal, 2 ciliated, and 2 secretory cell clusters. With chemical exposure, the proportion of cells assigned to keratin 5+ basal cells decreased, whereas the proportion of cells aligned to secretory cell clusters increased compared with control exposures. Functional pathway analysis identified interferon signaling and antigen processing/presentation as pathways commonly upregulated after diacetyl or nitrogen mustard exposure in a ciliated cell cluster. Conversely, the response of airway basal cells differed significantly with upregulation of the unfolded protein response in diacetyl-exposed basal cells, not seen in nitrogen mustard-exposed cultures. These new insights provide early identification of airway epithelial signatures common to BO-associated chemical exposures.NEW & NOTEWORTHY Bronchiolitis obliterans (BO) is a devastating fibrotic lung disease of the small airways, or bronchioles. This original manuscript uses single-cell RNA sequencing for identifying common signatures of chemically exposed airway epithelial cells in BO induction. Chemical exposure reduced the proportion of keratin 5+ basal cells while increasing the proportion of keratin 4+ suprabasal cells. Functional pathways contributory to these shifts differed significantly across exposures. These new results highlight similarities and differences in BO induction across exposures.

Epithelial-immune cell interactions in allergic diseases

Epithelial/immune interactions are characterized by the different properties of the various epithelial tissues, the mediators involved, and the varying immune cells that initiate, sustain, or abrogate allergic diseases on the surface. The intestinal mucosa, respiratory mucosa, and regular skin feature structural differences according to their primary function and surroundings. In the context of these specialized functions, the active role of the epithelium in shaping immune responses is increasingly recognizable. Crosstalk between epithelial and immune cells plays an important role in maintaining homeostatic conditions. While cells of the myeloid cell lineage, mainly macrophages, are the dominating immune cell population in the skin and the respiratory tract, lymphocytes comprise most intraepithelial immune cells in the intestine under healthy conditions. Common to all surface epithelia is the fact that innate immune cells represent the first line of immunosurveillance that either directly defeats invading pathogens or initiates and coordinates more effective successive immune responses involving adaptive immune cells and effector cells. Pharmacological approaches for the treatment of allergic and chronic inflammatory diseases involving epithelial barriers target immunological mediators downstream of the epithelium (such as IL-4, IL-5, IL-13, and IgE). The next generation of therapeutics involves upstream events of the inflammatory cascade, such as epithelial-derived alarmins and related mediators.

Roles of tissue-resident immune cells in immunotherapy of non-small cell lung cancer

Non-small cell lung cancer (NSCLC) is the most common and lethal type of lung cancer, with limited treatment options and poor prognosis. Immunotherapy offers hope for improving the survival and quality of life of NSCLC patients, but its efficacy depends on the tumor immune microenvironment (TME). Tissue-resident immune cells are a subset of immune cells that reside in various tissues and organs, and play an important role in fighting tumors. In NSCLC, tissue-resident immune cells are heterogeneous in their distribution, phenotype, and function, and can either promote or inhibit tumor progression and response to immunotherapy. In this review, we summarize the current understanding on the characteristics, interactions, and roles of tissue-resident immune cells in NSCLC. We also discuss the potential applications of tissue-resident immune cells in NSCLC immunotherapy, including immune checkpoint inhibitors (ICIs), other immunomodulatory agents, and personalized cell-based therapies. We highlight the challenges and opportunities for developing targeted therapies for tissue-resident immune cells and optimizing existing immunotherapeutic approaches for NSCLC patients. We propose that tissue-resident immune cells are a key determinant of NSCLC outcome and immunotherapy response, and warrant further investigation in future research.

Durable immunity to SARS-CoV-2 in both lower and upper airways achieved with a gorilla adenovirus (GRAd) S-2P vaccine in non-human primates

SARS-CoV-2 continues to pose a global threat, and current vaccines, while effective against severe illness, fall short in preventing transmission. To address this challenge, there's a need for vaccines that induce mucosal immunity and can rapidly control the virus. In this study, we demonstrate that a single immunization with a novel gorilla adenovirus-based vaccine (GRAd) carrying the pre-fusion stabilized Spike protein (S-2P) in non-human primates provided protective immunity for over one year against the BA.5 variant of SARS-CoV-2. A prime-boost regimen using GRAd followed by adjuvanted S-2P (GRAd+S-2P) accelerated viral clearance in both the lower and upper airways. GRAd delivered via aerosol (GRAd(AE)+S-2P) modestly improved protection compared to its matched intramuscular regimen, but showed dramatically superior boosting by mRNA and, importantly, total virus clearance in the upper airway by day 4 post infection. GrAd vaccination regimens elicited robust and durable systemic and mucosal antibody responses to multiple SARS-CoV-2 variants, but only GRAd(AE)+S-2P generated long-lasting T cell responses in the lung. This research underscores the flexibility of the GRAd vaccine platform to provide durable immunity against SARS-CoV-2 in both the lower and upper airways.

Histological and immunohistochemical characterization of mucosa-associated lymphoid tissue and antigen-presenting cells in trachea and lung of cattle

The presence of bronchus-associated lymphoid tissue (BALT) and its structural components has been described in different healthy animal species and in animals with diseases of the respiratory tract. In contrast to normal mammals, BALT is absent in healthy human adult lungs, but has been found in the lungs of children. The histological characteristics of organized mucosa-associated lymphoid tissue (MALT), its subsets of immune cells and their in situ distribution in the lung of healthy subadult and adult cattle shows close similarities with BALT in humans and other animal species such as sheep, horses and pigs. This study clearly demonstrates that organized MALT also occurs in the tracheal mucosa of cattle. The absence of tracheal MALT and BALT in calves suggest that these structures are not constitutive. In the mucosa of bovine trachea, bronchi and bronchioli, MHC II+ and CD11c+ dendritic cells (DCs) are located in the epithelium and in the lamina propria mucosae. These DCs are already present in calves soon after birth. Examination of tangential epithelial sheets shows that in the bovine tracheal epithelium, like in man and rat, a dense network of MHC II+ and CD11c+ DCs exists and that their number is considerably higher than in conventional transverse sections. In the bovine tracheal and bronchial epithelium, MHC II+ DCs are extending their dendrites towards the lumen indicating that these DCs possibly are involved in sampling of luminal antigens. The presence of significantly higher numbers of MHC II+ DCs in the tracheal and bronchial/bronchiolar mucosa of older cattle in than in calves possibly results from local stimulation with exogenous antigens during postnatal life. Detection of DCs expressing the costimulatory molecules CD80 and CD86 in calves and cattle suggests maturation of DCs, which is most likely induced by stimulation with exogenous antigens.

Early innate cell interactions with Mycobacterium tuberculosis in protection and pathology of tuberculosis

Tuberculosis (TB) remains a significant global health challenge, claiming the lives of up to 1.5 million individuals annually. TB is caused by the human pathogen Mycobacterium tuberculosis (Mtb), which primarily infects innate immune cells in the lungs. These immune cells play a critical role in the host defense against Mtb infection, influencing the inflammatory environment in the lungs, and facilitating the development of adaptive immunity. However, Mtb exploits and manipulates innate immune cells, using them as favorable niche for replication. Unfortunately, our understanding of the early interactions between Mtb and innate effector cells remains limited. This review underscores the interactions between Mtb and various innate immune cells, such as macrophages, dendritic cells, granulocytes, NK cells, innate lymphocytes-iNKT and ILCs. In addition, the contribution of alveolar epithelial cell and endothelial cells that constitutes the mucosal barrier in TB immunity will be discussed. Gaining insights into the early cellular basis of immune reactions to Mtb infection is crucial for our understanding of Mtb resistance and disease tolerance mechanisms. We argue that a better understanding of the early host-pathogen interactions could inform on future vaccination approaches and devise intervention strategies.

The effect of Toll-like receptor agonists on the immunogenicity of MVA-SARS-2-S vaccine after intranasal administration in mice

Background and aims

Modified Vaccinia virus Ankara (MVA) represents a promising vaccine vector for respiratory administration to induce protective lung immunity including tertiary lymphoid structure, the bronchus-associated lymphoid tissue (BALT). However, MVA expressing the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Spike protein (MVA-SARS-2-S) required prime-boost administration to induce high titers of anti-Spike antibodies in serum and bronchoalveolar lavage (BAL). As the addition of adjuvants enables efficient tailoring of the immune responses even to live vaccines, we tested whether Toll-like receptor (TLR)-agonists affect immune responses induced by a single dose of intranasally applied MVA-SARS-2-S.

Methods

We intranasally immunized C57BL/6 mice with MVA-SARS-2-S vaccine in the presence of either TLR3 agonist polyinosinic polycytidylic acid [poly(I:C)], TLR4 agonist bacterial lipopolysaccharide (LPS) from Escherichia coli, or TLR9 agonist CpG oligodeoxynucleotide (CpG ODN) 1826. At different time-points after immunization, we analyzed induced immune responses using flow cytometry, immunofluorescent microscopy, and ELISA.

Results

TLR agonists had profound effects on MVA-SARS-2-S-induced immune responses. At day 1 post intranasal application, the TLR4 agonist significantly affected MVA-induced activation of dendritic cells (DCs) within the draining bronchial lymph nodes, increasing the ratio of CD11b+CD86+ to CD103+CD86+ DCs. Nevertheless, the number of Spike-specific CD8+ T cells within the lungs at day 12 after vaccination was increased in mice that received MVA-SARS-2-S co-administered with TLR3 but not TLR4 agonists. TLR9 agonist did neither significantly affect MVA-induced DC activation nor the induction of Spike-specific CD8+ T cells but reduced both number and size of bronchus-associated lymphoid tissue. Surprisingly, the addition of all TLR agonists failed to boost the levels of Spike-specific antibodies in serum and bronchoalveolar lavage.

Conclusions

Our study indicates a potential role of TLR-agonists as a tool to modulate immune responses to live vector vaccines. Particularly TLR3 agonists hold a promise to potentiate MVA-induced cellular immune responses. On the other hand, additional research is necessary to identify optimal combinations of agonists that could enhance MVA-induced humoral responses.

The functional response of human monocyte-derived macrophages to serum amyloid A and Mycobacterium tuberculosis infection

Introduction

In the course of tuberculosis (TB), the level of major acute phase protein, namely serum amyloid A (hSAA-1), increases up to a hundredfold in the pleural fluids of infected individuals. Tubercle bacilli infecting the human host can be opsonized by hSAA-1, which affects bacterial entry into human macrophages and their intracellular multiplication.

Methods

We applied global RNA sequencing to evaluate the functional response of human monocyte-derived macrophages (MDMs), isolated from healthy blood donors, under elevated hSAA-1 conditions and during infection with nonopsonized and hSAA-1-opsonized Mycobacterium tuberculosis (Mtb). In the same infection model, we also examined the functional response of mycobacteria to the intracellular environment of macrophages in the presence and absence of hSAA-1. The RNASeq analysis was validated using qPCR. The functional response of MDMs to hSAA-1 and/or tubercle bacilli was also evaluated for selected cytokines at the protein level by applying the Milliplex system.

Findings

Transcriptomes of MDMs cultured in the presence of hSAA-1 or infected with Mtb showed a high degree of similarity for both upregulated and downregulated genes involved mainly in processes related to cell division and immune response, respectively. Among the most induced genes, across both hSAA-1 and Mtb infection conditions, CXCL8, CCL15, CCL5, IL-1β, and receptors for IL-7 and IL-2 were identified. We also observed the same pattern of upregulated pro-inflammatory cytokines (TNFα, IL-6, IL-12, IL-18, IL-23, and IL-1) and downregulated anti-inflammatory cytokines (IL-10, TGFβ, and antimicrobial peptide cathelicidin) in the hSAA-1 treated-MDMs or the phagocytes infected with tubercle bacilli. At this early stage of infection, Mtb genes affected by the inside microenvironment of MDMs are strictly involved in iron scavenging, adaptation to hypoxia, low pH, and increasing levels of CO2. The genes for the synthesis and transport of virulence lipids, but not cholesterol/fatty acid degradation, were also upregulated.

Conclusion

Elevated serum hSAA-1 levels in tuberculosis enhance the response of host phagocytes to infection, including macrophages that have not yet been in contact with mycobacteria. SAA induces antigen processing and presentation processes by professional phagocytes reversing the inhibition caused by Mtb infection.

A comprehensive review of highly pathogenic avian influenza (HPAI) H5N1: An imminent threat at doorstep

Avian influenza viruses (AIVs) are globally challenging due to widespread circulation and high mortality rates. Highly pathogenic avian influenza (HPAI) strains like H5N1 have caused significant outbreaks in birds. Since 2003 to 14 July 2023, the World Health Organization (WHO) has documented 878 cases of HPAI H5N1 infection in humans and 458 (52.16%) fatalities in 23 countries. Recent outbreaks in wild birds, domestic birds, sea lions, minks, and etc., and the occurrence of genetic variations among HPAI H5N1 strains raise concerns about potential transmission and public health risks. This paper aims to provide a comprehensive overview of the current understanding and new insights into HPAI H5N1. It begins with an introduction to the significance of studying this virus and highlighting the need for updated knowledge. The origin and evaluation of HPAI H5N1 are examined, shedding light on its emergence, and spread across different geographic regions. The genome organization and structural biology of the H5N1 virus are explored, providing insights into its molecular composition and key structural features. This manuscript also delves into the phylogeny, evolution, mutational trends, reservoirs, and transmission routes of HPAI H5N1. The immune response against HPAI H5N1 and its implications for vaccine development are analyzed, along with an exploration of the pathogenesis and clinical manifestations of HPAI H5N1 in human cases. Furthermore, diagnostic tools and preventive and therapeutic strategies are discussed, highlighting the current approaches and potential future directions for better management of the potential pandemic.

Pulmonary inflammation promoted by type-2 dendritic cells is a feature of human and murine schistosomiasis

Schistosomiasis is a parasitic disease affecting over 200 million people in multiple organs, including the lungs. Despite this, there is little understanding of pulmonary immune responses during schistosomiasis. Here, we show type-2 dominated lung immune responses in both patent (egg producing) and pre-patent (larval lung migration) murine Schistosoma mansoni (S. mansoni) infection. Human pre-patent S. mansoni infection pulmonary (sputum) samples revealed a mixed type-1/type-2 inflammatory cytokine profile, whilst a case-control study showed no significant pulmonary cytokine changes in endemic patent infection. However, schistosomiasis induced expansion of pulmonary type-2 conventional dendritic cells (cDC2s) in human and murine hosts, at both infection stages. Further, cDC2s were required for type-2 pulmonary inflammation in murine pre-patent or patent infection. These data elevate our fundamental understanding of pulmonary immune responses during schistosomiasis, which may be important for future vaccine design, as well as for understanding links between schistosomiasis and other lung diseases.

Canine Distemper Virus Alters Defense Responses in an Ex Vivo Model of Pulmonary Infection

Canine distemper virus (CDV), belonging to the genus Morbillivirus, is a highly contagious pathogen. It is infectious in a wide range of host species, including domestic and wildlife carnivores, and causes severe systemic disease with involvement of the respiratory tract. In the present study, canine precision-cut lung slices (PCLSs) were infected with CDV (strain R252) to investigate temporospatial viral loads, cell tropism, ciliary activity, and local immune responses during early infection ex vivo. Progressive viral replication was observed during the infection period in histiocytic and, to a lesser extent, epithelial cells. CDV-infected cells were predominantly located within the bronchial subepithelial tissue. Ciliary activity was reduced in CDV-infected PCLSs, while viability remained unchanged when compared to controls. MHC-II expression was increased in the bronchial epithelium on day three postinfection. Elevated levels of anti-inflammatory cytokines (interleukin-10 and transforming growth factor-β) were observed in CDV-infected PCLSs on day one postinfection. In conclusion, the present study demonstrates that PCLSs are permissive for CDV. The model reveals an impaired ciliary function and an anti-inflammatory cytokine response, potentially fostering viral replication in the lung during the early phase of canine distemper.

The Respiratory Commensal Bacterium Corynebacterium pseudodiphtheriticum as a Mucosal Adjuvant for Nasal Vaccines

Previously, we demonstrated that nasally administered Corynebacterium pseudodiphteriticum 090104 (Cp) or its bacterium-like particles (BLPs) increase the resistance of mice against bacterial and viral respiratory pathogens by modulating the innate immunity. In this work, we evaluated the ability of Cp and BLPs to stimulate alveolar macrophages, and to enhance the humoral immune response induced by a commercial vaccine against Streptococcus pneumoniae. In the first set of experiments, Cp or the BLPs were incubated with primary cultures of murine alveolar macrophages and the phagocytic activity, and the production of cytokines was evaluated. The results revealed that Cp and BLPs were efficiently phagocyted by respiratory macrophages and that both treatments triggered the production of TNF-α, IFN-γ, IL-6, and IL-1β. In the second set of experiments, 3-week-old Swiss mice were intranasally immunized at days 0, 14, and 28 with the pneumococcal vaccine Prevenar®13 (PCV), Cp + PCV, or BLPs + PCV. On day 33, samples of bronco-alveolar lavages (BAL) and serum were collected for the study of specific antibodies. In addition, immunized mice were challenged with S. pneumoniae serotypes 6B or 19F on day 33 and sacrificed on day 35 (day 2 post-infection) to evaluate the resistance to the infection. Both Cp + PCV and BLPs + PCV groups had higher specific serum IgG and BAL IgA antibodies than the PCV control mice. In addition, the mice that were immunized with Cp + PCV or BLPs + PCV had lower lung and blood pneumococcal cell counts as well as lower levels of BAL albumin and LDH, indicating a reduced lung damage compared to the control mice. Improved levels of anti-pneumococcal antibodies were also detected in the serum and BAL samples after the challenges with the pathogens. The results demonstrated that C. pseudodiphteriticum 090104 and its bacterium-like particles are capable of stimulating the respiratory innate immune system serving as adjuvants to potentiate the adaptive humoral immune response. Our study is a step forward in the positioning of this respiratory commensal bacterium as a promising mucosal adjuvant for vaccine formulations aimed at combating respiratory infectious diseases.

Genetic differences between smokers and never-smokers with lung cancer

Smoking is a major risk factor for lung cancer, therefore lung cancer epidemiological trends reflect the past trends of cigarette smoking to a great extent. The geographic patterns in mortality closely follow those in incidence. Although lung cancer is strongly associated with cigarette smoking, only about 15% of smokers get lung cancer, and also some never-smokers develop this malignancy. Although less frequent, lung cancer in never smokers is the seventh leading cause of cancer deaths in both sexes worldwide. Lung cancer in smokers and never-smokers differs in many aspects: in histological types, environmental factors representing a risk, and in genes associated with this disease. In this review, we will focus on the genetic differences between lung cancer in smokers versus never-smokers: gene expression, germ-line polymorphisms, gene mutations, as well as ethnic and gender differences. Finally, treatment options for smokers and never-smokers will be briefly reviewed.

Development of Adaptive Immunity and Its Role in Lung Remodeling

Asthma is characterized by airflow limitations resulting from bronchial closure, which can be either reversible or fixed due to changes in airway tissue composition and structure, also known as remodeling. Airway remodeling is defined as increased presence of mucins-producing epithelial cells, increased thickness of airway smooth muscle cells, angiogenesis, increased number and activation state of fibroblasts, and extracellular matrix (ECM) deposition. Airway inflammation is believed to be the main cause of the development of airway remodeling in asthma. In this chapter, we will review the development of the adaptive immune response and the impact of its mediators and cells on the elements defining airway remodeling in asthma.

Phenotypic and Transcriptional Changes of Pulmonary Immune Responses in Dogs Following Canine Distemper Virus Infection

Canine distemper virus (CDV), a morbillivirus within the family Paramyxoviridae, is a highly contagious infectious agent causing a multisystemic, devastating disease in a broad range of host species, characterized by severe immunosuppression, encephalitis and pneumonia. The present study aimed at investigating pulmonary immune responses of CDV-infected dogs in situ using immunohistochemistry and whole transcriptome analyses by bulk RNA sequencing. Spatiotemporal analysis of phenotypic changes revealed pulmonary immune responses primarily driven by MHC-II⁺, Iba-1⁺ and CD204⁺ innate immune cells during acute and subacute infection phases, which paralleled pathologic lesion development and coincided with high viral loads in CDV-infected lungs. CD20⁺ B cell numbers initially declined, followed by lymphoid repopulation in the advanced disease phase. Transcriptome analysis demonstrated an increased expression of transcripts related to innate immunity, antiviral defense mechanisms, type I interferon responses and regulation of cell death in the lung of CDV-infected dogs. Molecular analyses also revealed disturbed cytokine responses with a pro-inflammatory M1 macrophage polarization and impaired mucociliary defense in CDV-infected lungs. The exploratory study provides detailed data on CDV-related pulmonary immune responses, expanding the list of immunologic parameters potentially leading to viral elimination and virus-induced pulmonary immunopathology in canine distemper.

Tissue-resident immunity in the lung: a first-line defense at the environmental interface

The lung is a vital organ that incessantly faces external environmental challenges. Its homeostasis and unimpeded vital function are ensured by the respiratory epithelium working hand in hand with an intricate fine-tuned tissue-resident immune cell network. Lung tissue-resident immune cells span across the innate and adaptive immunity and protect from infectious agents but can also prove to be pathogenic if dysregulated. Here, we review the innate and adaptive immune cell subtypes comprising lung-resident immunity and discuss their ontogeny and role in distinct respiratory diseases. An improved understanding of the role of lung-resident immunity and how its function is dysregulated under pathological conditions can shed light on the pathogenesis of respiratory diseases.