Regulatory T Cells in Respiratory Health and Diseases

Nebulized platelet-derived extracellular vesicles attenuate chronic cigarette smoke-induced murine emphysema

Chronic obstructive pulmonary disease (COPD) is a prevalent lung disease usually resulting from cigarette smoking (CS). Cigarette smoking induces oxidative stress, which causes inflammation and alveolar epithelial cell apoptosis and represents a compelling therapeutic target for COPD. Purified human platelet-derived exosome product (PEP) is endowed with antioxidant enzymes and immunomodulatory molecules that mediate tissue repair. In this study, a murine model of CS-induced emphysema was used to determine whether nebulized PEP can influence the development of CS-induced emphysema through the mitigation of oxidative stress and inflammation in the lung. Nebulization of PEP effectively delivered the PEP vesicles into the alveolar region, with evidence of their uptake by type I and type II alveolar epithelial cells and macrophages. Lung function testing and morphometric assessment showed a significant attenuation of CS-induced emphysema in mice treated with nebulized PEP thrice weekly for 4 weeks. Whole lung immuno-oncology RNA sequencing analysis revealed that PEP suppressed several CS-induced cell injuries and inflammatory pathways. Validation of inflammatory cytokines and apoptotic protein expression on the lung tissue revealed that mice treated with PEP had significantly lower levels of S100A8/A9 expressing macrophages, higher levels of CD4+/FOXP3+ Treg cells, and reduced NF-κB activation, inflammatory cytokine production, and apoptotic proteins expression. Further validation using in vitro cell culture showed that pretreatment of alveolar epithelial cells with PEP significantly attenuated CS extract-induced apoptotic cell death. These data show that nebulization of exosomes like PEP can effectively deliver exosome cargo into the lung, mitigate CS-induced emphysema in mice, and suppress oxidative lung injury, inflammation, and apoptotic alveolar epithelial cell death.

Molecular Hydrogen as a Promising Therapy Could Be Linked With Increased Resting Treg Cells or Decreased Fas+ T Cell Subsets in a IgG4-PF-ILD Patient: A Case Report

BACKGROUND/AIM

Progressive fibrosing interstitial lung disease (PF-ILD) refers to a group of chronic lung conditions commonly associated with immunoglobulin G4-related disorders. It is characterized by progressive scarring (fibrosis) within the pulmonary interstitium, resulting in respiratory failure and early mortality. Some patients do not respond to standard therapeutic interventions. Numerous studies have confirmed the anti-inflammatory and antioxidant properties of molecular hydrogen in various disease models.

CASE REPORT

In this report, we present a case study of an 85-year-old female diagnosed with suspected IgG4-related PF-ILD complicated by hospital-acquired pneumonia. On the fourth day of hydrogen-assisted therapy, a noticeable improvement in lung infiltrations was observed in chest X-rays as the patient gradually progressed towards weaning off mechanical ventilation. To assess treatment responses, we compared immune phenotypes before and after hydrogen treatment. A marked increase was observed in resting regulatory T cell levels after treatment, accompanied by a notable decrease in Fas+ helper T cell and cytotoxic T cell subtypes.

CONCLUSION

This case study highlights the effectiveness of hydrogen-assisted therapy in managing PF-ILD complicated by pneumonia, warranting further research in the future.

Molecular Mechanisms Responsible for the Therapeutic Potential of Mesenchymal Stem Cell-Derived Exosomes in the Treatment of Lung Fibrosis

Mesenchymal stem cell-derived exosomes (MSC-Exos) are nano-sized extracellular vesicles which contain various MSC-sourced anti-fibrotic, immunoregulatory and angio-modulatory proteins (growth factors, immunoregulatory cytokines, chemokines), lipids, and nucleic acids (messenger RNA and microRNAs). Due to their lipid envelope, MSC-Exos easily by-pass all barriers in the body and deliver their cargo directly in target cells, modulating their viability, proliferation, phenotype and function. The results obtained in recently published experimental studies demonstrated beneficial effects of MSC-Exos in the treatment of lung fibrosis. MSC-Exos reduced activation of fibroblasts and prevented their differentiation in myofibroblasts. By delivering MSC-sourced immunoregulatory factors in lung-infiltrated monocytes and T cells, MSC-Exos modulate their function, alleviating on-going inflammation and fibrosis. MSC-Exos may also serve as vehicles for the target delivery of anti-fibrotic and immunomodulatory agents, enabling enhanced attenuation of lung fibrosis. Although numerous pre-clinical studies have demonstrated the therapeutic potential of MSC-Exos in the treatment of pulmonary fibrosis, there are several challenges that currently hinder their clinical implementation. Therefore, in this review article, we summarized current knowledge and we discussed future perspectives regarding molecular and cellular mechanisms which were responsible for the anti-fibrotic, anti-inflammatory and immunoregulatory properties of MSC-Exos, paving the way for their clinical use in the treatment of lung fibrosis.

N-acetyl cysteine augments adipose tissue-derived stem cell efficacy on inflammatory markers and regulatory T cell system balance in an allergic asthma model

BACKGROUND

Allergic asthma is a destructive inflammatory process in the respiratory system. The anti-inflammatory and antioxidant effects of N-acetylcysteine (NAC) have been reported in patients with obstructive pulmonary disease. On the other hand, several studies have shown the modulatory effects of mesenchymal stem cells on the immune system and inflammatory responses. Accordingly, the purpose of the current study was to evaluate the effect of administration of adipose tissue-derived stem cells (ADSCs) plus NAC on regulatory T cell system balance in an allergic asthma model.

METHODS

Eighty Sprague- Dawley rats were randomly divided into the following groups: Control, Plasmalite, Allergic asthma, Allergic asthma + ADSCs, NAC, Allergic asthma + NAC, Allergic asthma + ADSCs + NAC and Allergic asthma + Prednisolone. at the end of the experiment, arterial blood gas analysis, inflammatory cell counts in bronchoalveolar lavage fluid (BALF), inflammatory cytokine concentration, total IgE and specific OVA-IgE levels, gene expression levels of CD4+-T cell subsets, pulmonary indicators, edema, and lung histopathology were evaluated in all groups.

RESULTS

Administration of NAC plus ADSCs demonstrated a significant decrease in total WBC and eosinophil counts, which was in line with remarkable decrease in IL-17 and TNF-α concentrations and increases in IL-10 level compared with other treated groups. NAC plus ADSC treatment showed significant increases in Treg gene expression, although Th17 and Th2 expression significantly decreased compared with that in prednisolone- treated rats.

CONCLUSION

The results of the present study documented that the administration of ADSCs plus NAC has an inhibitory effect on the inflammation caused by allergic asthma in a rat model. The improvement of inflammatory indexes was significantly higher than that with prednisolone treatment.

Association between Increased Risk of Pneumonia with ICS in COPD: A Continuous Variable Analysis of Patient Factors from the IMPACT Study

INTRODUCTION

Despite the proven benefits of inhaled corticosteroid (ICS)-containing triple therapy for chronic obstructive pulmonary disease (COPD), clinicians limit patient exposure to ICS due to the risk of pneumonia. However, there are multiple factors associated with the risk of pneumonia in patients with COPD. This post hoc analysis of IMPACT trial data aims to set the risks associated with ICS into a context of specific patient-related factors that contribute to the risk of pneumonia.

METHODS

The 52-week, double-blind IMPACT trial randomized patients with symptomatic COPD and ≥1 exacerbation in the prior year 2:2:1 to once-daily fluticasone furoate (FF)/umeclidinium (UMEC)/vilanterol (VI), FF/VI or UMEC/VI. Annual rate of on-treatment pneumonias in the intent-to-treat population associated with age, body mass index (BMI), percent predicted forced expiratory volume in 1 s (FEV1) and blood eosinophil count (BEC) was evaluated.

RESULTS

This analysis revealed that the annual rate of pneumonia showed the lowest risk at the age of 50 years. The 95% confidence intervals (CI) between ICS-containing and non-ICS containing treatments diverged in ages > 63 years, suggesting a significantly increased ICS-related risk in older patients. In contrast, the annual rate of pneumonia rose in both groups below BMI of 22.5 kg/m2, but above that, there was no relationship to pneumonia rate and no differential effect between the two groups. The relationship between BEC and pneumonia was flat up to > 300/µL cells with ICS-containing treatment and then rose. In contrast, the rate of pneumonia with non-ICS containing treatment appeared to increase at a lower level of BEC (~ 200/µL).

CONCLUSIONS

There was little evidence of a differential effect of older age, lower BMI, lower FEV1 and BEC on the pneumonia rate between ICS-containing and non-ICS containing treatments. This analysis points to the need for a balanced approach to risk versus benefit in the use of ICS-containing treatments in COPD.

CLINICAL TRIAL REGISTRATION

IMPACT ClinicalTrials.gov number, NCT02164513.

Boosting regulatory T cell-dependent immune tolerance by activation of p53

Regulatory T cells (Tregs) have critical roles in maintaining immune hemostasis and have important anti-inflammatory functions in diseases. Recently, we identified that CX-5461 (a selective RNA polymerase I inhibitor and p53 activator) acted as a potent immunosuppressive agent, which prevented allogeneic acute rejection in animal models via a molecular mechanism distinct from all those of conventional immunosuppressive drugs. Unexpectedly, we discovered that CX-5461 could promote Treg differentiation. In this review, we have summarized the evidence for a potential role of p53 in mediating Treg differentiation and its possible mechanisms, including regulation of FoxP3 transcription, regulation of the expression of PTEN (phosphatase and tensin homolog), as well as protein-protein interaction with the transcription factor STAT5 (signal transducer and activator of transcription 5). Evidence also suggests that pharmacological p53 activators may potentially be used to boost Treg-mediated immune tolerance. Based on these data, we argue that novel p53 activators such as CX-5461 may represent a distinct class of immunosuppressants that repress conventional T cell-mediated alloimmunity with concomitant boosting of Treg-dependent immune tolerance.

Regulatory T cells in lung disease and transplantation

Pulmonary disease can refer to the disease of the lung itself or the pulmonary manifestations of systemic diseases, which are often connected to the malfunction of the immune system. Regulatory T (Treg) cells have been shown to be important in maintaining immune homeostasis and preventing inflammatory damage, including lung diseases. Given the increasing amount of evidence linking Treg cells to various pulmonary conditions, Treg cells might serve as a therapeutic strategy for the treatment of lung diseases and potentially promote lung transplant tolerance. The most potent and well-defined Treg cells are Foxp3-expressing CD4+ Treg cells, which contribute to the prevention of autoimmune lung diseases and the promotion of lung transplant rejection. The protective mechanisms of Treg cells in lung disease and transplantation involve multiple immune suppression mechanisms. This review summarizes the development, phenotype and function of CD4+Foxp3+ Treg cells. Then, we focus on the therapeutic potential of Treg cells in preventing lung disease and limiting lung transplant rejection. Furthermore, we discussed the possibility of Treg cell utilization in clinical applications. This will provide an overview of current research advances in Treg cells and their relevant application in clinics.

The functional adaptation of effector Foxp3+ regulatory T cells to pulmonary inflammation

During infections, the timings of effector differentiation of pulmonary immune responses are of paramount importance, as pathogen persistence and unsuppressed inflammation can rapidly lead to a loss of function, increased frailty, and death. Thus, both an efficient clearance of the danger and a rapid resolution of inflammation are critical to host survival. We now know that tissue-localized FoxP3+ regulatory T cells, a subset of CD4+ T cells, are highly attuned to the type of immune response, acquiring unique phenotypic characteristics that allow them to adapt their suppressive functions with the nature of inflammatory cells. To achieve this, activated effector TREG cells acquire specialized TH 1, TH 2, and TH 17-like characteristics that allow them to migrate, survive, and time their function(s) through refined mechanisms. Herein, we describe how this process requires a unique developmental path that includes the acquisition of master transcription factors and the expression of receptors adapted to sense local danger signals that are found during pulmonary inflammation. In turn, we offer an overview of how these characteristics promote the capacity of local effector TREG cells to proliferate, survive, and display suppressive strategies to resolve lung injury.

Host gut-derived Bacillus probiotics supplementation improves growth performance, serum and liver immunity, gut health, and resistive capacity against Vibrio harveyi infection in hybrid grouper (♀Epinephelus fuscoguttatus × ♂Epinephelus lanceolatus)

Several reports have revealed the vital role that probiotics play in fish growth and health. However, few works are available for host gut-derived probiotics on the growth, immunity, and gut microbiota of fish, especially in hybrid grouper (♀Epinephelus fuscoguttatus × ♂Epinephelus lanceolatus) due to their isolation difficulty and functional verification. This study aimed at assessing 3 host gut-derived Bacillus species' effects on the growth, immune and antioxidant-biochemical responses, haematological parameters, intestinal morphology, immune-related gene expression, gut microbiota, and disease resistance against Vibrio harveyi in hybrid grouper. A total of 480 hybrid grouper (initial weight = 9.03 ± 0.02 g) were randomly allotted into 4 groups, namely, the group fed a basal diet without probiotic inclusion (control, B0), the group fed the basal diet with Bacillus velezensis GPSAK4 (BV), the group fed the basal diet with Bacillus subtilis GPSAK9 (BS), and the group fed the basal diet with Bacillus tequilensis GPSAK2 (BT) strains at 1.0 × 10⁹ CFU/g. After a 6-week feeding trial, the results revealed significant improvements (P < 0.05) in the growth performance, whole fish-body proximate composition, blood haematological parameters, serum, liver, and intestinal biochemical indexes, intestinal morphology, and protection against V. harveyi pathogen in the probiotic-treated groups compared with the untreated. Additionally, the expressions of intestinal tight junction genes (occludin and ZO1), pro- and anti-inflammatory genes, including IL1β, IL6, IL8, TNFα, MyD88, IL10, and TGFβ, were upregulated (P < 0.05) after Bacillus species administration. Host gut-derived Bacillus supplementation shaped the gut microbiota by significantly increasing (P < 0.05) the relative abundance of Proteobacteria, Bacteroidetes, Actinobacteria (except the BS group), Acidobacteria (except the BT group), Cyanobacteria (except the BV and BT groups), and Verrucomicrobia phyla, as well as known beneficial genera (Romboutsia, Turicibacter, Epulopiscium, Clostridium_sensu_stricto 1 and 13, Lactobacillus, and Bacillus), but significantly decreased (P < 0.05) the abundance of Firmicutes, Chloroflexi, and Fusobacteria phyla, and purported pathogenic genera (Staphylococcus and Photobacterium) compared with the control group. Collectively, the results suggest that B. velezensis GPSAK4, B. subtilis GPSAK9 (especially this strain), B. tequilensis GPSAK2 dietary supplementation at 1.0 × 10⁹ CFU/g has positive effects on the intestinal health of hybrid grouper via microbial composition modulation, thus enhancing the assimilation and absorption of nutrients to boost fish growth, immunity, and disease resistance.

Distribution and chemotactic mechanism of CD4+ T cells in traumatic tracheal stenosis

A systemic and local inflammatory immune imbalance is thought to be the cause of traumatic tracheal stenosis (TS). However, with CD4+ T lymphocytes being the predominant immune cells in TS, the mechanism of action and recruitment has not been described. In our research, using flow cytometry, ELISA, immunofluorescence, and Transwell chamber assays, the expression, distribution, and potential chemotactic function of CD4+ T cells in TS patients were examined before and after treatment. The results showed that the untreated group had significantly more CD4+ T cells and their secreted TGF-β1 than the treated group. Additionally, the untreated group's CD4+ T cells showed a significant rise in CCL22 and CCL1, as well as a larger proportion of CCR4 and CCR8. CD4+ T cells and CD68+ macrophages located in TS also expressed CCL1 and CCL22. In vitro, anti-CCL1 and anti-CCL22 can partially block the chemoattractant effect of TS bronchoalveolar lavage (BAL) on purified CD4+ T cells. The findings of this study indicated that TS contained unbalanced CD4 immune cells that were actively recruited locally by CCR4/CCL22 and CCR8/CCL1. As a result, it is anticipated that CD4 immune rebalancing can serve as a novel treatment for TS.

Circulating Regulatory T Cell Subsets in Patients with Sarcoidosis

Over recent years, many researchers have supported the autoimmune theory of sarcoidosis. The presence of uncontrolled inflammatory response on local and system levels in patients with sarcoidosis did not define that the immunoregulatory mechanisms could be affected. The aim of this study was to evaluate the distribution and the disturbance circulating Treg cell subsets in the peripheral blood in patients with sarcoidosis.

MATERIALS AND METHODS

A prospective comparative study was performed in 2016-2018 (34 patients with sarcoidosis (men (67.6%), women (32.3%)) were examined). Healthy subjects-the control group (n = 40). The diagnosis of pulmonary sarcoidosis was performed according to the standard criteria. We used two ten-color combinations of antibodies for Treg immunophenotyping. The first one contained CD39-FITC, CD127-PE, CCR4-PE/Dazzle™ 594, CD25-PC5.5, CD161-PC7, CD4-APC, CD8-APC-AF700, CD3-APC/Cy7, HLA-DR-PacBlue, and CD45 RA-BV 510™, while the second consisted of CXCR3-Alexa Fluor 488, CD25-РЕ, CXCR5-РЕ/Dazzle™ 594, CCR4-PerСP/Сy5.5, CCR6-РЕ/Cy7, CD4-АPC, CD8 АPC-AF700, CD3-АPC/Cy7, CCR7-BV 421, and CD45 RA-BV 510. The flow cytometry data were analyzed by using Kaluza software v2.3. A statistical analysis was performed with Statistica 7.0 and GraphPad Prism 8 software packages.

RESULTS OF THE STUDY

Primarily, we found that patients with sarcoidosis had decreased absolute numbers of Treg cells in circulation. We noted that the level of CCR7-expressing Tregs decreased in patients with sarcoidosis vs. the control group (65.55% (60.08; 70.60) vs. 76.93% (69.59; 79.86) with p < 0.001). We noticed that the relative numbers of CD45RA-CCR7+ Tregs decreased in patients with sarcoidosis (27.11% vs. 35.43%, p < 0.001), while the frequency of CD45 RA-CCR7- and CD45RA+ CCR7- Tregs increased compared to the control group (33.3% vs. 22.73% and 0.76% vs. 0.51% with p < 0.001 and p = 0.028, respectively). CXCR3-expressing Treg cell subsets-Th1-like CCR60078CXCR3+ Tregs and Th17.1-like CCR6+ CXCR3+ Tregs-significantly increased in patients with sarcoidosis vs. the control group (14.4% vs. 10.5% with p < 0.01 and 27.9% vs. 22.8% with p < 0.01, respectively). Furthermore, the levels of peripheral blood EM Th17-like Tregs significantly decreased in the sarcoidosis group vs. the control group (36.38% vs. 46.70% with p < 0.001). Finally, we found that CXCR5 expression was increased in CM Tregs cell subsets in patients with sarcoidosis.

CONCLUSIONS

Our data indicated a decrease in circulating Tregs absolute numbers and several alterations in Treg cell subsets. Moreover, our results highlight the presence of increased levels of CM CXCR5+ follicular Tregs in the periphery that could be linked with the imbalance of follicular Th cell subsets and alterations in B cell, based on the immune response. The balance between the two functionally distinct Treg cell populations-Th1-like and Th17-like Tregs-could be used in sarcoidosis diagnosis and the determination of prognosis and disease outcomes. Furthermore, we want to declare that analysis of Treg numbers of phenotypes could fully characterize their functional activity in peripherally inflamed tissues.

Novel Strategy for Alzheimer’s Disease Treatment through Oral Vaccine Therapy with Amyloid Beta

Alzheimer’s disease (AD) is a neuropathology characterized by progressive cognitive impairment and dementia. The disease is attributed to senile plaques, which are aggregates of amyloid beta (Aβ) outside nerve cells; neurofibrillary tangles, which are filamentous accumulations of phosphorylated tau in nerve cells; and loss of neurons in the brain tissue. Immunization of an AD mouse model with Aβ-eliminated pre-existing senile plaque amyloids and prevented new accumulation. Furthermore, its effect showed that cognitive function can be improved by passive immunity without side effects, such as lymphocyte infiltration in AD model mice treated with vaccine therapy, indicating the possibility of vaccine therapy for AD. Further, considering the possibility of side effects due to direct administration of Aβ, the practical use of the safe oral vaccine, which expressed Aβ in plants, is expected. Indeed, administration of this oral vaccine to Alzheimer’s model mice reduced Aβ accumulation in the brain. Moreover, almost no expression of inflammatory IgG was observed. Therefore, vaccination prior to Aβ accumulation or at an early stage of accumulation may prevent Aβ from causing AD.

Where do T cell subsets stand in SARS-CoV-2 infection: an update

An outbreak of coronavirus disease 2019 (COVID-19) emerged in China in December 2019 and spread so rapidly all around the globe. It’s continued and spreading more dangerously in India and Brazil with higher mortality rate. Understanding of the pathophysiology of COVID-19 depends on unraveling of interactional mechanism of SARS-CoV-2 and human immune response. The immune response is a complex process, which can be better understood by understanding the immunological response and pathological mechanisms of COVID-19, which will provide new treatments, increase treatment efficacy, and decrease mortality associated with the disease. In this review we present a amalgamate viewpoint based on the current available knowledge on COVID-19 which includes entry of the virus and multiplication of virus, its pathological effects on the cellular level, immunological reaction, systemic and organ presentation. T cells play a crucial role in controlling and clearing viral infections. Several studies have now shown that the severity of the COVID-19 disease is inversely correlated with the magnitude of the T cell response. Understanding SARS-CoV-2 T cell responses is of high interest because T cells are attractive vaccine targets and could help reduce COVID-19 severity. Even though there is a significant amount of literature regarding SARS-CoV-2, there are still very few studies focused on understanding the T cell response to this novel virus. Nevertheless, a majority of these studies focused on peripheral blood CD4+ and CD8+ T cells that were specific for viruses. The focus of this review is on different subtypes of T cell responses in COVID-19 patients, Th17, follicular helper T (TFH), regulatory T (Treg) cells, and less classical, invariant T cell populations, such as δγ T cells and mucosal-associated invariant T (MAIT) cells etc that could influence disease outcome.

Lung Cancer in the Course of COPD-Emerging Problems Today

Tobacco smoking remains the main cause of tobacco-dependent diseases like lung cancer, chronic obstructive pulmonary disease (COPD), in addition to cardiovascular diseases and other cancers. Whilst the majority of smokers will not develop either COPD or lung cancer, they are closely related diseases, occurring as co-morbidities at a higher rate than if they were independently triggered by smoking. A patient with COPD has a four- to six-fold greater risk of developing lung cancer independent of smoking exposure, when compared to matched smokers with normal lung function. The 10 year risk is about 8.8% in the COPD group and only 2% in patients with normal lung function. COPD is not a uniform disorder: there are different phenotypes. One of them is manifested by the prevalence of emphysema and this is complicated by malignant processes most often. Here, we present and discuss the clinical problems of COPD in patients with lung cancer and against lung cancer in the course of COPD. There are common pathological pathways in both diseases. These are inflammation with participation of macrophages and neutrophils and proteases. It is known that anticancer immune regulation is distorted towards immunosuppression, while in COPD the elements of autoimmunity are described. Cytotoxic T cells, lymphocytes B and regulatory T cells with the important role of check point molecules are involved in both processes. A growing number of lung cancer patients are treated with immune check point inhibitors (ICIs), and it was found that COPD patients may have benefits from this treatment. Altogether, the data point to the necessity for deeper analysis and intensive research studies to limit the burden of these serious diseases by prevention and by elaboration of specific therapeutic options.

Mucosal viral infection induces a regulatory T cell activation phenotype distinct from tissue residency in mouse and human tissues

Regulatory T cells (Tregs) mediate immune homeostasis, yet also facilitate nuanced immune responses during infection, balancing pathogen control while limiting host inflammation. Recent studies have identified Treg populations in non-lymphoid tissues that are phenotypically distinct from Tregs in lymphoid tissues (LT), including performance of location-dependent roles. Mucosal tissues serve as critical barriers to microbes while performing unique physiologic functions, so we sought to identify distinct phenotypical and functional aspects of mucosal Tregs in the female reproductive tract. In healthy human and mouse vaginal mucosa, we found that Tregs are highly activated compared to blood or LT Tregs. To determine if this phenotype reflects acute activation or a general signature of vaginal tract (VT)-residency, we infected mice with HSV-2 to discover that VT Tregs express granzyme-B (GzmB) and acquire a VT Treg signature distinct from baseline. To determine the mechanisms that drive GzmB expression, we performed ex vivo assays to reveal that a combination of type-I interferons and interleukin-2 is sufficient for GzmB expression. Together, we highlight that VT Tregs are activated at steady state and become further activated in response to infection; thus, they may exert robust control of local immune responses, which could have implications for mucosal vaccine design.

Airway Basal Cells, Protectors of Epithelial Walls in Health and Respiratory Diseases

The airway epithelium provides a critical barrier to the outside environment. When its integrity is impaired, epithelial cells and residing immune cells collaborate to exclude pathogens and to heal tissue damage. Healing is achieved through tissue-specific stem cells: the airway basal cells. Positioned near the basal membrane, airway basal cells sense and respond to changes in tissue health by initiating a pro-inflammatory response and tissue repair via complex crosstalks with nearby fibroblasts and specialized immune cells. In addition, basal cells have the capacity to learn from previous encounters with the environment. Inflammation can indeed imprint a certain memory on basal cells by epigenetic changes so that sensitized tissues may respond differently to future assaults and the epithelium becomes better equipped to respond faster and more robustly to barrier defects. This memory can, however, be lost in diseased states. In this review, we discuss airway basal cells in respiratory diseases, the communication network between airway basal cells and tissue-resident and/or recruited immune cells, and how basal cell adaptation to environmental triggers occurs.

Increased cytotoxic T-cells in the airways of adults with former bronchopulmonary dysplasia

Rationale

Bronchopulmonary dysplasia (BPD) in preterm-born infants is a risk factor for chronic airway obstruction in adulthood. Cytotoxic T-cells are implicated in COPD, but their involvement in BPD is not known.

Objectives

To characterise the distribution of airway T-cell subsets in adults with a history of BPD.

Methods

Young adults with former BPD (n=22; median age 19.6 years), age-matched adults born preterm (n=22), patients with allergic asthma born at term (n=22) and healthy control subjects born at term (n=24) underwent bronchoalveolar lavage (BAL). T-cell subsets in BAL were analysed using flow cytometry.

Results

The total number of cells and the differential cell counts in BAL were similar among the study groups. The percentage of CD3⁺CD8⁺ T-cells was higher (p=0.005) and the proportion of CD3⁺CD4⁺ T-cells was reduced (p=0.01) in the BPD group, resulting in a lower CD4/CD8 ratio (p=0.007) compared to the healthy controls (median 2.2 versus 5.3). In BPD and preterm-born study subjects, both CD3⁺CD4⁺ T-cells (r_s=0.38, p=0.03) and CD4/CD8 ratio (r_s=0.44, p=0.01) correlated positively with forced expiratory volume in 1 s (FEV₁). Furthermore, CD3⁺CD8⁺ T-cells were negatively correlated with both FEV₁ and FEV₁/forced vital capacity (r_s= −0.44, p=0.09 and r_s= −0.41, p=0.01, respectively).

Conclusions

Young adults with former BPD have a T-cell subset pattern in the airways resembling features of COPD. Our findings are compatible with the hypothesis that CD3⁺CD8⁺ T-cells are involved in mechanisms behind chronic airway obstruction in these patients.

Young adults with former BPD display more cytotoxic T-cells in the airways than healthy subjects. These T-cells correlate with FEV₁. Thus, cytotoxic T-cells may contribute to the pathology behind chronic airway obstruction in adults with former BPD.https://bit.ly/3soI4lK

Normal ex vivo mesenchymal stem cell function combined with abnormal immune profiles sets the stage for informative cell therapy trials in idiopathic pulmonary fibrosis patients

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive pulmonary disease characterized by aberrant tissue remodeling, formation of scar tissue within the lungs and continuous loss of lung function. The areas of fibrosis seen in lungs of IPF patients share many features with normal aging lung including cellular senescence. The contribution of the immune system to the etiology of IPF remains poorly understood. Evidence obtained from animal models and human studies suggests that innate and adaptive immune processes can orchestrate existing fibrotic responses. Currently, there is only modest effective pharmacotherapy for IPF. Mesenchymal stem cells (MSCs)-based therapies have emerged as a potential option treatment of IPF. This study characterizes the functionality of autologous MSCs for use as an IPF therapy and presents an attempt to determine whether the disease occurring in the lungs is associated with an alterated immune system.

METHODS

Comprehensive characterization of autologous adipose-derived MSCs (aMSCs) from 5 IPF patient and 5 age- and gender-matched healthy controls (HC) was done using flow cytometry, PCR (ddPCR), multiplex Luminex xMAP technology, confocal microscopy self-renewal capacity and osteogenic differentiation. Additionally, multi-parameter quantitative flow cytometry of unmanipulated whole blood of 15 IPF patients and 87 (30 age- and gender-matched) HC was used to analyze 110 peripheral phenotypes to determine disease-associated changes in the immune system.

RESULTS

There are no differences between autologous aMSCs from IPF patients and HC in their stem cell properties, self-renewal capacity, osteogenic differentiation, secretome content, cell cycle inhibitor marker levels and mitochondrial health. IPF patients had altered peripheral blood immunophenotype including reduced B cells subsets, increased T cell subsets and increased granulocytes demonstrating disease-associated alterations in the immune system.

CONCLUSIONS

Our results indicate that there are no differences in aMSC properties from IPF patients and HC, suggesting that autologous aMSCs may be an acceptable option for IPF therapy. The altered immune system of IPF patients may be a valuable biomarker for disease burden and monitoring therapeutic response.

Mucosal tissue regulatory T cells are integral in balancing immunity and tolerance at portals of antigen entry

Foxp3+ regulatory T cells (Tregs) are a subset of CD4+ T cells that exert suppressive control over other immune cells. Tregs are critical for preventing systemic autoimmunity and maintaining peripheral tolerance, and yet they also assist in orchestration of immunity to pathogenic insult, wherein they limit collateral immunopathology and assist in facilitating a fine balance between immune tolerance and effector activity. Tregs have been extensively studied in lymphoid tissues, and a growing body of work has characterized phenotypically distinct Tregs localized in various nonlymphoid tissue compartments. These tissue Tregs can perform location-specific, alternative functions, highlighting their dynamic, context-dependent roles. Tregs have also been identified in mucosal tissues where specialized physiological functions are paramount, including helping the host to respond appropriately to pathogenic versus innocuous antigens that are abundant at mucosal portals of antigen entry. As in other tissue Treg compartments, mucosal Tregs in the respiratory, gastrointestinal, and genitourinary tracts are distinct from circulating counterparts and can carry out mucosa-specific functions as well as classic suppressive functions that are the hallmark of Tregs. In this review, we summarize current knowledge regarding mucosal Tregs in both health and disease.

Benzo[a]pyrene immunogenetics and immune archetype reprogramming of lung

Overexposure to carcinogenic precursor, benzo[a]pyrene [BaP], modulates the lung immune microenvironment. The present review seeks to elucidate novel pathways behind the tumor effect of BaP in the lungs, emphasizing immunomodulatory mediators and immune cells. In this review, BaP reprograms lung immune microenvironment through modulating transforming growth factor-beta (TGF-β), programmed cell death 1 (PD-1), cytotoxic T lymphocyte antigen-4 (CTLA-4), Interleukin 12 (IL-12), indoleamine 2,3 dioxygenase (IDO), forkhead box protein P3 (FOXP3) and interferon-gamma (IFN-γ) levels. Moreover, BaP modulated lung immune cellular architecture such as dendritic cells, T cells, Tregs, macrophages, neutrophils, and myeloid-derived suppressor cells (MDSCs). All mentioned changes in immune architecture and mediators lead to the induction of lung cancer.

Immunomodulatory Role of Nutrients: How Can Pulmonary Dysfunctions Improve?

Nutrition is an important tool that can be used to modulate the immune response during infectious diseases. In addition, through diet, important substrates are acquired for the biosynthesis of regulatory molecules in the immune response, influencing the progression and treatment of chronic lung diseases, such as asthma and chronic obstructive pulmonary disease (COPD). In this way, nutrition can promote lung health status. A range of nutrients, such as vitamins (A, C, D, and E), minerals (zinc, selenium, iron, and magnesium), flavonoids and fatty acids, play important roles in reducing the risk of pulmonary chronic diseases and viral infections. Through their antioxidant and anti-inflammatory effects, nutrients are associated with better lung function and a lower risk of complications since they can decrease the harmful effects from the immune system during the inflammatory response. In addition, bioactive compounds can even contribute to epigenetic changes, including histone deacetylase (HDAC) modifications that inhibit the transcription of proinflammatory cytokines, which can contribute to the maintenance of homeostasis in the context of infections and chronic inflammatory diseases. These nutrients also play an important role in activating immune responses against pathogens, which can help the immune system during infections. Here, we provide an updated overview of the roles played by dietary factors and how they can affect respiratory health. Therefore, we will show the anti-inflammatory role of flavonoids, fatty acids, vitamins and microbiota, important for the control of chronic inflammatory diseases and allergies, in addition to the antiviral role of vitamins, flavonoids, and minerals during pulmonary viral infections, addressing the mechanisms involved in each function. These mechanisms are interesting in the discussion of perspectives associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and its pulmonary complications since patients with severe disease have vitamins deficiency, especially vitamin D. In addition, researches with the use of flavonoids have been shown to decrease viral replication in vitro. This way, a full understanding of dietary influences can improve the lung health of patients.

Sarcoidosis and autoimmunity

PURPOSE OF REVIEW

Sarcoidosis is a poorly understood multisystem granulomatous disease that frequently involves the lungs but can affect any organ system. In this review, we summarize recent developments in the understanding of the immune dysregulation seen in sarcoidosis and propose a new expanded definition of human autoimmunity in sarcoidosis, and the implications it would have on treating sarcoidosis with targeted immunotherapy regimens in the future.

RECENT FINDINGS

Sarcoidosis has been linked to infectious organisms like Mycobacterium and Cutibacterium, and certain manifestations of sarcoidosis have been linked to specific HLA alleles, but the overall pathogenesis remains uncertain. Sarcoidosis patients have similar patterns of cellular immune dysregulation seen in other autoimmune diseases like rheumatoid arthritis, and recent large-scale population studies show that sarcoidosis frequently presents with other autoimmune diseases.

SUMMARY

Advancements in the understanding of sarcoidosis support its consideration as an autoimmune disease. Sarcoidosis patients carry a higher risk of comorbid autoimmune conditions which offers an excellent opportunity to further understand autoimmunity and explore biologic therapies in sarcoidosis treatment, and furthermore will better targeted immunotherapy regimens for sarcoidosis patients in the future.

Mannose-Modified Chitosan Poly(lactic-co-glycolic acid) Microspheres Act as a Mannose Receptor-Mediated Delivery System Enhancing the Immune Response

The mannose receptor (MAN-R)-targeted delivery system is commonly used to deliver antigens to macrophages or immature dendritic cells (DCs) to promote the efficiency of antigen presentation. To maximize the enhancement effects of chitosan (CS) and induce an efficient humoral and cellular immune response against an antigen, we encapsulated ovalbumin (OVA) in poly(lactic-co-glycolic acid) (PLGA) microspheres (MPs) and conjugated it with MAN-modified CS to obtain MAN-R-targeting nano-MPs (MAN-CS-OVA-PLGA-MPs). The physicochemical properties, drug loading rate, and immunomodulation activity of MAN-CS-OVA-PLGA-MPs were evaluated. In vitro, MAN-CS-OVA-PLGA-MPs (80 μg mL⁻¹) could enhance the proliferation of DCs and increase their phagocytic efficiency. In vivo, MAN-CS-OVA-PLGA-MPs significantly increased the ratio of CD3⁺CD4⁺/CD3⁺CD8⁺ T cells, increased CD80⁺, CD86⁺, and MHC II expression in DCs, and improved OVA-specific IgG, IgG1, IgG2a, and IgG2b antibodies. Moreover, MAN-CS-OVA-PLGA-MPs promoted cytokine (IFN-γ, IL-4, and IL-6) production in mice. Taken together, our results show that MAN-CS-OVA-PLGA-MPs may act by activating the T cells to initiate an immune response by promoting the maturation of dendritic cells and improving their antigen presentation efficiency. The current study provides a basis for the use of MAN-CS-OVA-PLGA-MPs as an antigen and adjuvant delivery system targeting the MAN-R on the surface of macrophages and dendritic cells.

Toward an understanding of regulatory T cells in COVID-19: A systematic review

A more detailed understanding of Treg cells in COVID-19 infection will broaden our knowledge of the COVID-19 immunopathology and give us more insight into the curative immune-based strategies. We systematically searched electronic databases (PubMed, Google Scholar, EMBASE) and identified 18 eligible studies. Despite the inconsistencies between the results, we observed a trend toward decreasing Treg levels in severe COVID-19 patients. This finding underlines the hypothesis that Tregs play a role in the pathogenesis of COVID-19. Further studies on Tregs' functional aspects are necessary to illustrate Tregs' potential role in COVID-19 disease.

Fluoride Can Damage the Spleen of Mice by Perturbing Th1/Th2 Cell Balance

To investigate the mechanism of fluoride-induced splenic toxicity, 0, 25, 50, and 100 mg/L sodium fluoride (NaF) were administered in male mice via drinking water for 90 days. After NaF treatment, the histological structure of the spleen, the proportion of helper T 1 cell (Th1) and helper T 2 cell (Th2), and the relative expression levels of cytokines and T-bet and GATA3 were analyzed. The results showed that 50 and 100 mg/L NaF consumption can change the normal structure of mouse spleen and the proportion of Th1/Th2 cells. It also decreased the mRNA expression levels of IL-2, INF-γ, and TGF-β, but increased the levels of IL-4, IL-6, and IL-10. Importantly, fluoride increased the protein expression of GATA3 but decreased the expression of T-bet. Our findings indicate that superfluous fluoride intake damages the balance of Th1/Th2 cells by changing the levels of T-bet and GATA3 in the spleen, and further changes the expression of Th1/Th2 cell-related cytokines in the spleen microenvironment, eventually leading to spleen injury.

Mycobacterium-Induced Th1, Helminths-Induced Th2 Cells and the Potential Vaccine Candidates for Allergic Asthma: Imitation of Natural Infection

Bronchial asthma is one of the most chronic pulmonary diseases and major public health problems. In general, asthma prevails in developed countries than developing countries, and its prevalence is increasing in the latter. For instance, the hygiene hypothesis demonstrated that this phenomenon resulted from higher household hygienic standards that decreased the chances of infections, which would subsequently increase the occurrence of allergy. In this review, we attempted to integrate our knowledge with the hygiene hypothesis into beneficial preventive approaches for allergic asthma. Therefore, we highlighted the studies that investigated the correlation between allergic asthma and the two different types of infections that induce the two major antagonizing arms of T cells. This elucidation reflects the association between various types of natural infections and the immune system, which is predicted to support the main objective of the current research on investigating of the benefits of natural infections, regardless their immune pathways for the prevention of allergic asthma. We demonstrated that natural infection with Mycobacterium tuberculosis (Mtb) prevents the development of allergic asthma, thus Bacille Calmette-Guérin (BCG) vaccine is suggested at early age to mediate the same prevention particularly with increasing its efficiency through genetic engineering-based modifications. Likewise, natural helminth infections might inhabit the allergic asthma development. Therefore, helminth-derived proteins at early age are good candidates for designing vaccines for allergic asthma and it requires further investigation. Finally, we recommend imitation of natural infections as a general strategy for preventing allergic asthma that increased dramatically over the past decades.

Atrial fibrillation in COVID-19: A review of possible mechanisms

A relationship between COVID-19 infection and an increasing incidence of atrial fibrillation has been observed. However, the underlying pathophysiology as a precipitant to AF has not been reviewed. This paper will consider the possible pathological and immunological AF mechanisms as a result, of COVID-19 infection. We discuss the role myocardial microvascular pericytes expressing the ACE-2 receptor and their potential for an organ-specific cardiac involvement with COVID-19. Dysfunctional microvascular support by pericytes or endothelial cells may increase the propensity for AF via increased myocardial inflammation, fibrosis, increased tissue edema, and interstitial hydrostatic pressure. All of these factors can lead to electrical perturbances at the tissue and cellular level. We also consider the contribution of Angiotensin, pulmonary hypertension, and regulatory T cells as additional contributors to AF during COVID-19 infection. Finally, reference is given to two common drugs, corticosteroids and metformin, in COVID-19 and how they might influence AF incidence.

Activation of pro- and anti-inflammatory responses in lung tissue injury during the acute phase of PRRSV-1 infection with the virulent strain Lena

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Lena virulent strain caused an increase in sera levels of IFN-γ and IL-6.

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Lung viral load and PRRSV-N-protein⁺ cells were inversely correlated with CD163⁺ macrophages in the lung.

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CD14⁺ cells infiltrated interstitium to possibly replenish macrophages subsets.

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Lena-induced microscopic lung injury was linked to an increase of iNOS⁺ cells.

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The increase of CD200R1⁺ and FoxP3⁺ cells was associated with the course of lung injury.

Porcine reproductive and respiratory syndrome virus (PRRSV) plays a key role in porcine respiratory disease complex modulating the host immune response and favouring secondary bacterial infections. Pulmonary alveolar macrophages (PAMs) are the main cells supporting PRRSV replication, with CD163 as the essential receptor for viral infection. Although interstitial pneumonia is by far the representative lung lesion, suppurative bronchopneumonia is described for PRRSV virulent strains. This research explores the role of several immune markers potentially involved in the regulation of the inflammatory response and sensitisation of lung to secondary bacterial infections by PRRSV-1 strains of different virulence. Conventional pigs were intranasally inoculated with the virulent subtype 3 Lena strain or the low virulent subtype 1 3249 strain and euthanised at 1, 3, 6 and 8 dpi. Lena-infected pigs exhibited more severe clinical signs, macroscopic lung score and viraemia associated with an increase of IL-6 and IFN-γ in sera compared to 3249-infected pigs. Extensive areas of lung consolidation corresponding with suppurative bronchopneumonia were observed in Lena-infected pigs. Lung viral load and PRRSV-N-protein⁺ cells were always higher in Lena-infected animals. PRRSV-N-protein⁺ cells were linked to a marked drop of CD163⁺ macrophages. The number of CD14⁺ and iNOS⁺ cells gradually increased along PRRSV-1 infection, being more evident in Lena-infected pigs. The frequency of CD200R1⁺ and FoxP3⁺ cells peaked late in both PRRSV-1 strains, with a strong correlation between CD200R1⁺ cells and lung injury in Lena-infected pigs. These results highlight the role of molecules involved in the earlier and higher extent of lung lesions in piglets infected with the virulent Lena strain, pointing out the activation of routes potentially involved in the restraint of the local inflammatory response.