Functional characterization of T cell populations in a mouse model of chronic obstructive pulmonary disease

Psoralen attenuates cigarette smoke extract-induced inflammation by modulating CD8+ T lymphocyte recruitment and chemokines via the JAK2/STAT1 signaling pathway

Chronic obstructive pulmonary disease (COPD) is a respiratory inflammatory disease. Psoralen (PSO) is the main pharmacological component identified from Bu-Shen-Fang-Chuan formula which has been traditionally used in treatment of COPD, yet its efficacy in COPD inflammation were unreported. In this study, we aimed to elucidate the anti-inflammatory potential of PSO in COPD and unravel the underlying mechanisms, focusing on T lymphocyte recruitment and the modulation of chemokines, namely monokine induced by interferon-gamma (CXCL9), interferon inducible protein 10 (CXCL10), and interferon inducible T-Cell alpha chemoattractant (CXCL11). In vitro, RAW264.7 was stimulated by interferon (IFN)-γ + cigarette smoke extract (CSE) and were treated with PSO (2.5, 5, 10 μM), then the levels of chemokines and the activation of Janus kinase (JAK)/Signal transducer and activator of transcription 1 (STAT1) pathway were analyzed by real time PCR and western blot. In vivo, a murine model was established by intraperitoneal injection of CSE on day 1, 8, 15, and 22, then treated with PSO (10 mg/kg). Our experiments in vitro illustrated that PSO reduced the levels of CXCL9, CXCL10, and CXCL11, and decreased the protein phosphorylation levels of JAK2 and STAT1. Additionally, PSO effectively improved inflammatory infiltration and decreased the proportion of CD8+ T cells in CSE-exposed mice. Furthermore, PSO reduced the levels of CXCL9, CXCL10, and CXCL11 in bronchoalveolar lavage fluid (BALF) and lung tissue, and decreased the protein phosphorylation levels of JAK2 and STAT1. In conclusion, our results revealed the therapeutic potential of PSO for COPD inflammation, possibly mediated through the regulation of CD8+ T cell recruitment and chemokines via the JAK2/STAT1 signaling pathway.

Animal models and mechanisms of tobacco smoke-induced chronic obstructive pulmonary disease (COPD)

Chronic obstructive pulmonary disease (COPD) is the third leading cause of death worldwide, and its global health burden is increasing. COPD is characterized by emphysema, mucus hypersecretion, and persistent lung inflammation, and clinically by chronic airflow obstruction and symptoms of dyspnea, cough, and fatigue in patients. A cluster of pathologies including chronic bronchitis, emphysema, asthma, and cardiovascular disease in the form of hypertension and atherosclerosis variably coexist in COPD patients. Underlying causes for COPD include primarily tobacco use but may also be driven by exposure to air pollutants, biomass burning, and workplace related fumes and chemicals. While no single animal model might mimic all features of human COPD, a wide variety of published models have collectively helped to improve our understanding of disease processes involved in the genesis and persistence of COPD. In this review, the pathogenesis and associated risk factors of COPD are examined in different mammalian models of the disease. Each animal model included in this review is exclusively created by tobacco smoke (TS) exposure. As animal models continue to aid in defining the pathobiological mechanisms of and possible novel therapeutic interventions for COPD, the advantages and disadvantages of each animal model are discussed.

Contribution of adaptive immunity to human COPD and experimental models of emphysema

The pathophysiology of chronic obstructive pulmonary disease (COPD) and the undisputed role of innate immune cells in this condition have dominated the field in the basic research arena for many years. Recently, however, compelling data suggesting that adaptive immune cells may also contribute to the progressive nature of lung destruction associated with COPD in smokers have gained considerable attention. The histopathological changes in the lungs of smokers can be limited to the large or small airways, but alveolar loss leading to emphysema, which occurs in some individuals, remains its most significant and irreversible outcome. Critically, however, the question of why emphysema progresses in a subset of former smokers remained a mystery for many years. The recognition of activated and organized tertiary T- and B-lymphoid aggregates in emphysematous lungs provided the first clue that adaptive immune cells may play a crucial role in COPD pathophysiology. Based on these findings from human translational studies, experimental animal models of emphysema were used to determine the mechanisms through which smoke exposure initiates and orchestrates adaptive autoreactive inflammation in the lungs. These models have revealed that T helper (Th)1 and Th17 subsets promote a positive feedback loop that activates innate immune cells, confirming their role in emphysema pathogenesis. Results from genetic studies and immune-based discoveries have further provided strong evidence for autoimmunity induction in smokers with emphysema. These new findings offer a novel opportunity to explore the mechanisms underlying the inflammatory landscape in the COPD lung and offer insights for development of precision-based treatment to halt lung destruction.

Efferocytosis in lung mucosae: implications for health and disease

Efferocytosis is imperative to maintain lung homeostasis and control inflammation. Populations of lung macrophages are the main efferocytes in this tissue, responsible for controlling immune responses and avoiding unrestrained inflammation and autoimmunity through the expression of a plethora of receptors that recognize multiple 'eat me' signals on apoptotic cells. Efferocytosis is essentially anti-inflammatory and tolerogenic. However, in some situations, apoptotic cells phagocytosis can elicit inflammatory and immunogenic immune responses. Here, we summarized the current knowledge of the mechanisms of efferocytosis, and how any abnormality in this process may have an important contribution to the lung pathophysiology of many chronic inflammatory lung diseases such as asthma, acute lung injury, chronic obstructive pulmonary disease, and cystic fibrosis. Further, we consider the consequences of the dual role of efferocytosis on the susceptibility or resistance to pulmonary microbial infections. Understanding how efferocytosis works in different contexts will be useful to the development of new and more effective strategies to control the diversity of lung diseases.

Effect of Autoimmune Cell Therapy on Immune Cell Content in Patients with COPD: A Randomized Controlled Trial

Objective

To explore the effect of autoimmune cell therapy on immune cells in patients with chronic obstructive pulmonary disease (COPD) and to provide a reference for clinical treatment of COPD.

Methods

Sixty patients with stable COPD were randomly divided into control group and treatment group (n = 30). The control group was given conventional treatment, and the treatment group was given one autoimmune cell therapy on the basis of conventional treatment. The serum levels of CD3+ T cells, CD4+ T cells, CD8+ cells, B cells, and NK cells in the peripheral blood were detected by flow cytometry. Possible adverse reactions were detected at any time during treatment.

Results

There were no significant differences in the contents of CD3+ T cells, CD4+ T cells, CD8+ cells, B cells, and NK cells in the serum of the control group (P > 0.05). Compared with before treatment, the contents of CD3+ T cells, CD4+ T cells, CD8+ cells, B cells, and NK cells in the serum of the treatment group were significantly increased (P < 0.05). The ratio of CD4 + /CD8+ T cells in both control and treatment groups did not change significantly during treatment (P > 0.05). There were no significant differences in serum CD3+ T cells, CD4+ T cells, CD8+ cells, B cells, and NK cells in the treatment group at 30 days and 90 days after treatment (P > 0.05), but they were significantly higher than those in the control group (P < 0.05).

Conclusion

Autoimmune cell therapy can significantly increase the level of immune cells in the body and can be maintained for a long period of time, which has certain clinical benefits for recurrent respiratory tract infections and acute exacerbation in patients with COPD.

A New Prognostic Index PDPI for the Risk of Pneumonia Among Patients With Diabetes

Objective

Risk factors for the development of pneumonia among patients with diabetes mellitus are unclear. The aim of our study was to elucidate the potential risk factors and attempt to predict the probability of pneumonia based on the history of diabetes.

Methods

We performed a population-based, prospective multicenter cohort study of 1,043 adult patients with diabetes in China during 2017–2019. Demographic information, comorbidities, or laboratory examinations were collected.

Results

The study included 417 diabetic patients with pneumonia and 626 no-pneumonia-onset diabetic patients. The predictive risk factors were chosen on the basis of a multivariate logistic regression model to predict pneumonia among patients with diabetes including male sex [odds ratio (OR) = 1.72, 95% confidence interval (CI): 1.27–2.33, p < 0.001], age ≥ 75 years (OR = 2.31, 95% CI: 1.61–3.31, p < 0.001), body mass index < 25 (OR = 2.59, 95% CI: 1.92–3.50, p < 0.001), chronic obstructive pulmonary disease (OR = 6.58, 95% CI: 2.09–20.7, p = 0.001), hypertension (OR = 4.27, 95% CI: 3.12–5.85, p < 0.001), coronary heart disease (OR = 2.98, 95% CI: 1.61–5.52, p < 0.001), renal failure (OR = 1.82, 95% CI: 1.002–3.29, p = 0.049), cancer (OR = 3.57, 95% CI: 1.80–7.06, p < 0.001), use of insulin (OR = 2.28, 95% CI: 1.60–3.25, p < 0.001), and hemoglobin A1c ≥ 9% (OR = 2.70, 95% CI: 1.89–3.85, p < 0.001). A predictive nomogram was established. This model showed c-statistics of 0.811, and sensitivity and specificity were 0.717 and 0.780, respectively, under cut-off of 125 score.

Conclusion

We designed a clinically predictive tool for assessing the risk of pneumonia among adult patients with diabetes. This tool stratifies patients into relevant risk categories and may provide a basis for individually tailored intervention for the purpose of early prevention.

Enhanced lung inflammatory response in whole-body compared to nose-only cigarette smoke-exposed mice

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is characterized by a progressive and abnormal inflammatory response in the lungs, mainly caused by cigarette smoking. Animal models exposed to cigarette smoke (CS) are used to mimic human COPD but the use of different CS protocols makes it difficult to compare the immunological and structural consequences of using a nose-only or whole-body CS exposure system. We hypothesized that when using a standardized CS exposure protocol based on particle density and CO (carbon monoxide) levels, the whole-body CS exposure system would generate a more severe inflammatory response than the nose-only system, due to possible sensitization by uptake of CS-components through the skin or via grooming.

METHODS

In this study focusing on early COPD, mice were exposed twice daily 5 days a week to CS either with a nose-only or whole-body exposure system for 14 weeks to assess lung function, remodeling and inflammation.

RESULTS

At sacrifice, serum cotinine levels were significantly higher in the whole-body (5.3 (2.3-6.9) ng/ml) compared to the nose-only ((2.0 (1.8-2.5) ng/ml) exposure system and controls (1.0 (0.9-1.0) ng/ml). Both CS exposure systems induced a similar degree of lung function impairment, while inflammation was more severe in whole body exposure system. Slightly more bronchial epithelial damage, mucus and airspace enlargement were observed with the nose-only exposure system. More lymphocytes were present in the bronchoalveolar lavage (BAL) and lymph nodes of the whole-body exposure system while enhanced IgA and IgG production was found in BAL and to a lesser extent in serum with the nose-only exposure system.

CONCLUSION

The current standardized CS-exposure protocol resulted in a higher internal load of serum cotinine in the whole-body exposure system, which was associated with more inflammation. However, both exposure systems resulted in a similar lung function impairment. Data also highlighted differences between the two models in terms of lung inflammation and remodelling, and potential sensitization to CS. Researchers should be aware of these differences when designing their future studies for an early intervention in COPD.

A Network Pharmacology Approach to Explore the Potential Mechanisms of Yifei Sanjie Formula in Treating Pulmonary Fibrosis

Objective

Yifei Sanjie Formula (YFSJF) is an effective formula on pulmonary fibrosis (PF), which has been used in clinic for more than 30 years. In order to investigate the molecular mechanism of YFSJF in treating PF, network pharmacology was used to predict the cooperative ingredients and associated pathways.

Methods

Firstly, we collected potential active ingredients of YFSJF by TCMSP databases. Secondly, we obtained PF-associated targets through OMIM and Genecards database. Finally, metascape was applied for the analysis of GO terms and KEGG pathways.

Results

We screened out 76 potential active ingredients and 98 associated proteins. A total of 5715 items were obtained by GO enrichment analysis (P < 0.05), including 4632 biological processes, 444 cellular components, and 639 molecular functions. A total of 143 related KEGG pathways were enriched (P < 0.05), including IL-17 signaling pathway, T cell receptor signaling pathway, TNF signaling pathway, calcium signaling pathway, TH17 cell differentiation, HIF-1 signaling pathway, and PI3K-Akt signaling pathway.

Conclusion

YFSJF can interfere with immune and inflammatory response through multiple targets and pathways, which has a certain role in the treatment of PF. This study lays a foundation for future experimental research.

The role of CD8 + T lymphocytes in chronic obstructive pulmonary disease: a systematic review

OBJECTIVE AND DESIGN

This systematic review aims to establish the role of CD8 + T lymphocytes in COPD.

METHODS

Forty-eight papers published in the last 15 years were identified for inclusion.

RESULTS

CD8 + T-cells are increased in the lungs of patients with COPD (17 studies, 16 positive) whereas in the circulation, findings were inconclusive. Activation of CD8 + T-cells was enhanced in lungs (four studies, three positive) but cell phenotype was unclear. There was substantial evidence of a higher proportion of type 1 CD8 + (Tc1) cells in COPD (11 studies, 9 positive), though the population of type 2 (Tc2) cells was also increased (5 studies, 4 positive). CD8 + T-cells in COPD exhibited greater expression of cytotoxic proteins (five studies, five positive). Studies assessed a variety of questions so evidence was insufficient to draw firm conclusions. The role of CD8 + T-cells at acute exacerbation of COPD and also their contribution to alveolar destruction can only be hypothesised at this stage.

CONCLUSIONS

Not only is the number of CD8 + T-cells increased in COPD, these cells have increased capacity to exert effector functions and are likely to contribute to disease pathogenesis. Several mechanisms highlighted show promise for future investigation to consolidate current knowledge.

Th17/Treg imbalance in COPD development: suppressors of cytokine signaling and signal transducers and activators of transcription proteins

Th17/Treg imbalance contributes to chronic obstructive pulmonary disease (COPD) development and progression. However, intracellular signaling by suppressor of cytokine signaling (SOCS) 1 and SOCS3 and the proteins signal transducer and activator of transcription (STAT) 3 and STAT5 that orchestrate these imbalances are currently poorly understood. Thus, these proteins were investigated in C57BL/6 mice after exposure to cigarette smoke (CS) for 3 and 6 months. The expression of interleukin was measured by ELISA and the density of positive cells in peribronchovascular areas was quantified by immunohistochemistry. We showed that exposure to CS in the 3rd month first induced decreases in the numbers of STAT5+ and pSTAT5+ cells and the expression levels of TGF-β and IL-10. The increases in the numbers of STAT3+ and pSTAT3+ cells and IL-17 expression occurred later (6th month). These findings corroborate the increases in the number of SOCS1+ cells in both the 3rd and 6th months, with concomitant decreases in SOCS3+ cells at the same time points. Our results demonstrated that beginning with the initiation of COPD development, there was a downregulation of the anti-inflammatory response mediated by SOCS and STAT proteins. These results highlight the importance of intracellular signaling in Th17/Treg imbalance and the identification of possible targets for future therapeutic approaches.

Bufei Yishen Formula Restores Th17/Treg Balance and Attenuates Chronic Obstructive Pulmonary Disease via Activation of the Adenosine 2a Receptor

Bufei Yishen formula (BYF) is a Traditional Chinese Medicine (TCM) reported to ameliorate chronic obstructive pulmonary disease (COPD) by regulating the balance between T helper (Th) 17 and regulatory T (Treg) cells. However, its mechanism remains unknown. Therefore, this study aimed to explore the underlying mechanisms of BYF. Naïve CD4+ T cells were exposed to anti-CD3, anti-CD28, transforming growth factor (TGF)-β, and/or interleukin (IL)-6 to promote their differentiation into Th17 or Treg cells. A rat model of cigarette smoke- and bacterial infection-induced COPD was established and orally treated with BYF and/or an adenosine 2a receptor (A2aR) antagonist. Then, the rats were sacrificed, their lung tissues were removed for histological analysis, and their spleens were collected to evaluate Th17 and Treg cells. The results showed that BYF significantly suppressed Th17 cell differentiation and its related cytokines and enhanced Treg cell differentiation and its related cytokines. In addition, BYF activated the A2aR, increased the levels of p-signal transducer and activator of transcription (STAT)5, and decreased the level of p-STAT3 in Treg and Th17 cells. The A2aR antagonist suppressed the changes induced by BYF treatment in Th17 and Treg cells. Furthermore, the A2aR antagonist diminished the therapeutic effect of BYF on COPD, as indicated by the lung injury scores, bronchiole wall thickness, small pulmonary vessels wall thickness, bronchiole stenosis, alveolar diameters, decrease in inflammatory cytokines, increase in alveolar number, and lung functions. Similarly, the A2aR antagonist reversed the effects of BYF on the proportion of Th17 and Treg cells in the spleen. Additionally, BYF increased the protein and mRNA levels of A2aR and regulated the phosphorylation of STAT3 and STAT5 in spleen and lung tissues, which were inhibited by cotreatment with the A2aR antagonist. In conclusion, this study suggested that BYF exhibited its anti-COPD efficacy by restoring the Th17/Treg balance via activating A2aR, which may provide evidence for the clinical application of BYF in the treatment of COPD.

Innate Immunity and Cell Surface Receptors in the Pathogenesis of COPD: Insights from Mouse Smoking Models

Chronic obstructive pulmonary disease (COPD) is mainly associated with smoking habit. Inflammation is the major initiating process whereby neutrophils and monocytes are attracted into the lung microenvironment by external stimuli present in tobacco leaves and in cigarette smoke, which promote chemotaxis, adhesion, phagocytosis, release of superoxide anions and enzyme granule contents. A minority of smokers develops COPD and different molecular factors, which contribute to the onset of the disease, have been put forward. After many years of research, the pathogenesis of COPD is still an object of debate. In vivo models of cigarette smoke-induced COPD may help to unravel cellular and molecular mechanisms underlying the pathogenesis of COPD. The mouse represents the most favored animal choice with regard to the study of immune mechanisms due to its genetic and physiological similarities to humans, the availability of a large variability of inbred strains, the presence in the species of several genetic disorders analogous to those in man, and finally on the possibility to create models “made-to-measure” by genetic manipulation. The review outlines the different response of mouse strains to cigarette smoke used in COPD studies while retaining a strong focus on their relatability to human patients. These studies reveal the importance of innate immunity and cell surface receptors in the pathogenesis of pulmonary injury induced by cigarette smoking. They further advance the way in which we use wild type or genetically manipulated strains to improve our overall understanding of a multifaceted disease such as COPD. The structural and functional features, which have been found in the different strains of mice after chronic exposure to cigarette smoke, can be used in preclinical studies to develop effective new therapeutic agents for the different phenotypes in human COPD.

Role of Pneumocystis jirovecii infection in chronic obstructive pulmonary disease progression in an immunosuppressed rat Pneumocystis pneumonia model

Pneumocystis jirovecii (P. jirovecii), an opportunistic fungal pathogen, is the primary cause of Pneumocystis pneumonia (PCP), which affects immunocompromised individuals and leads to high morbidity and mortality. P. jirovecii colonization is associated with development of chronic obstructive pulmonary disease (COPD) in patients with HIV infection, and also non-sufferers, and in primate models of HIV infection. However, the mechanisms underlying P. jirovecii infection in the pathogenesis of COPD have yet to be fully elucidated. To investigate the pathogenicity of P. jirovecii infection and its role in COPD development, the present study established a PCP rat model induced by dexamethasone sodium phosphate injection. Expression of COPD-related biomarkers, including matrix metalloproteinases (MMPs) MMP-2, MMP-8, MMP-9, and MMP-12, and heat shock protein-27 (HSP-27), were quantified in the rat PCP model using reverse transcription-quantitative polymerase chain reaction, ELISA, western blot analysis, immunohistochemistry and gelatin zymography. Body weight, COPD symptoms, and pulmonary histopathology were assessed. Inflammatory cell counts in splenic tissues were measured using flow cytometry. It was identified that MMP and HSP-27 expression increased in the PCP rats, which was in agreement with previous literature. Therefore, it was hypothesized that P. jirovecii infection may have an important role in COPD development.

A Novel Animal Model of Emphysema Induced by Anti-Elastin Autoimmunity

Loss of immune tolerance to self-antigens can promote chronic inflammation and disrupt the normal function of multiple organs, including the lungs. Degradation of elastin, a highly insoluble protein and a significant component of the lung structural matrix, generates proinflammatory molecules. Elastin fragments (EFs) have been detected in the serum of smokers with emphysema, and elastin-specific T cells have also been detected in the peripheral blood of smokers with emphysema. However, an animal model that could recapitulate T cell-specific autoimmune responses by initiating and sustaining inflammation in the lungs is lacking. In this study, we report an animal model of autoimmune emphysema mediated by the loss of tolerance to elastin. Mice immunized with a combination of human EFs plus rat EFs but not mouse EFs showed increased infiltration of innate and adaptive immune cells to the lungs and developed emphysema. We cloned and expanded mouse elastin-specific CD4+ T cells from the lung and spleen of immunized mice. Finally, we identified TCR sequences from the autoreactive T cell clones, suggesting possible pathogenic TCRs that can cause loss of immune tolerance against elastin. This new autoimmune model of emphysema provides a useful tool to examine the immunological factors that promote loss of immune tolerance to self.

Louqin Zhisou Decoction Inhibits Mucus Hypersecretion for Acute Exacerbation of Chronic Obstructive Pulmonary Disease Rats by Suppressing EGFR-PI3K-AKT Signaling Pathway and Restoring Th17/Treg Balance

Airway mucus hypersecretion is the main pathogenic factor in acute exacerbation of chronic obstructive pulmonary disease (AECOPD) and the control of mucus secretion is closely associated with survival. Louqin Zhisou decoction (LQZS) has been found to improve lung function and reduce sputum in AECOPD patients, but the mechanism remains unclear. This study aimed to explore the mechanism of LQZS against mucus hypersecretion in lung tissues of rat AECOPD model. Wistar rats were used to establish AECOPD model by intratracheal instillation of LPS in combination with the continuous cigarette smoking. Rats were administrated LQZS/clarithromycin (CAM)/distilled water via gavage every day and all rats were sacrificed after 30 days. BALF and lung tissues were obtained. Lung morphology, cytokines levels, MUC5AC mRNA transcription and protein expression, phosphorylation of the EGFR-PI3K-AKT signaling pathway, and molecules involved in Th17/Treg balance were evaluated. The results demonstrated that LQZS protected rats from decline in pulmonary function and ameliorated lung injury. LQZS treatment decreased the number of goblet cells in airway and suppressed MUC5AC mRNA and protein expression of lung tissues. Furthermore, LQZS attenuated the level of phospho-EGFR, phospho-PI3K and phospho-AKT in AECOPD rats. In addition, LQZS could inhibit the production of proinflammatory cytokines in BALF, including IL-6 and IL-17A and downregulate the secretion of NE and MCP-1, indicating that LQZS could limit inflammatory responses in AECOPD. Moreover, LQZS reversed RORγt and Foxp3 expression, the key transcription factors of Th17 and Treg, respectively. In conclusion, this research demonstrated the inhibitory effects of LQZS against mucus hypersecretion in AECOPD via suppressing EGFR-PI3K-AKT signaling pathway and restoring Th17/Treg balance.

Th17/Treg imbalance in COPD progression: A temporal analysis using a CS-induced model

Background

The imbalance between pro- and anti-inflammatory immune responses plays a pivotal role in chronic obstructive pulmonary disease (COPD) development and progression. To clarify the pathophysiological mechanisms of this disease, we performed a temporal analysis of immune response-mediated inflammatory progression in a cigarette smoke (CS)-induced mouse model with a focus on the balance between Th17 and Treg responses.

Methods

C57BL/6 mice were exposed to CS for 1, 3 or 6 months to induce COPD, and the control groups were maintained under filtered air conditions for the same time intervals. We then performed functional (respiratory mechanics) and structural (alveolar enlargement) analyses. We also quantified the NF-κB, TNF-α, CD4, CD8, CD20, IL-17, IL-6, FOXP3, IL-10, or TGF-β positive cells in peribronchovascular areas and assessed FOXP3 and IL-10 expression through double-label immunofluorescence. Additionally, we evaluated the gene expression of NF-κB and TNF in bronchiolar epithelial cells.

Results

Our CS-induced COPD model exhibited an increased proinflammatory immune response (increased expression of the NF-κB, TNF-α, CD4, CD8, CD20, IL-17, and IL-6 markers) with a concomitantly decreased anti-inflammatory immune response (FOXP3, IL-10, and TGF-β markers) compared with the control mice. These changes in the immune responses were associated with increased alveolar enlargement and impaired lung function starting on the first month and third month of CS exposure, respectively, compared with the control mice.

Conclusion

Our results showed that the microenvironmental stimuli produced by the release of cytokines during COPD progression lead to a Th17/Treg imbalance.

How Simian Virus 40 Hijacks the Intracellular Protein Trafficking Pathway to Its Own Benefit … and Ours

Viruses efficiently transfer and express their genes in host cells and evolve to evade the host's defense responses. These properties render them highly attractive for use as gene delivery vectors in vaccines, gene, and immunotherapies. Among the viruses used as gene delivery vectors, the macaque polyomavirus Simian Virus 40 (SV40) is unique in its capacity to evade intracellular antiviral defense responses upon cell entry. We here describe the unique way by which SV40 particles deliver their genomes in the nucleus of permissive cells and how they prevent presentation of viral antigens to the host's immune system. The non-immunogenicity in its natural host is not only of benefit to the virus but also to us in developing effective SV40 vector-based treatments for today's major human diseases.

Restoring Th17/Treg balance via modulation of STAT3 and STAT5 activation contributes to the amelioration of chronic obstructive pulmonary disease by Bufei Yishen formula

ETHNOPHARMACOLOGY RELEVANCE

Bufei Yishen formula (BYF), a Traditional Chinese Medicine (TCM), has been extensively applied in clinical treatment of chronic obstructive pulmonary disease (COPD) and provides an effective treatment strategy for the syndrome of lung-kidney qi deficiency in COPD patients. Here, we investigated its anti-COPD mechanism in COPD rats in relation to the balance between T helper (Th) 17 cells and regulatory T (Treg) cells.

METHODS

Rat model of cigarette smoke- and bacterial infection-induced COPD was established, and orally treated with BYF for 12 consecutive weeks. Then, the rats were sacrificed, their lung tissues were removed for histological analysis, and spleens and mesenteric lymph nodes (MLNs) were collected to evaluate the Th17 and Treg cells.

RESULTS

Oral treatment of BYF markedly suppressed the disease progression and alleviated the pathological changes of COPD. It also decreased the bronchoalveolar lavage fluid (BALF) levels of pro-inflammatory cytokines, including IL-1β, IL-6, TNF-α and Th17-related IL-17A, and induced a significant increase in Treg-related IL-10. Furthermore, BYF treatment obviously decreased the proportion of CD4⁺RORγt⁺ T (Th17) cell and increased the proportion of CD4⁺CD25⁺Foxp3⁺ T (Treg) cell, leading to restore the Th17/Treg balance. BYF treated groups also decreased RORγt and increased Foxp3 expression in the spleens and MLNs. BYF further inhibited the phosphorylation of signal transducer and activator of transcription-3 (STAT3) and boosted the phosphorylation of STAT5, that were critical transcription factors for TH17 and Treg differentiation.

CONCLUSION

these results demonstrated that BYF exerted its anti-COPD efficacy by restoring Th17/Treg balance via reciprocally modulating the activities of STAT3 and STAT5 in COPD rats, which may help to elucidate the underlying immunomodulatory mode of BYF on COPD treatment.

Cigarette smoke exposure promotes differentiation of CD4+ T cells toward Th17 cells by CD40-CD40L costimulatory pathway in mice

Purpose

This study aimed to investigate the impact of cigarette smoke exposure upon CD40–CD40L ligation between bone marrow-derived dendritic cells (BMDCs)and CD4⁺T cells, and to examine the effects of cigarette smoke exposure upon differentiation of CD4⁺T cells toward Th17 cells through blockade of CD40-CD40L pathway in mice.

Methods

The study was processed in vivo and in vitro. In vivo, Th17 cells, CD40, interleukin (IL)-17A, and IL-27 in the lung tissues were quantified and compared between mice with and without cigarette smoke exposure. In vitro, Th17 cells, IL-17A, and IL-27 yielded by multiple cell cultivations in which BMDCs from mice with or without cigarette smoke exposure were fostered with CD4⁺ T cells from healthy mice spleens in the presence of antagonistic CD40 antibody and/or cigarette smoke extract (CSE) were quantified and compared. The flow cytometry was used to detect expressions of Th17 cells and CD40, and the liquid chip was used to detect levels of IL-17A and IL-27.

Results

Both in vivo exposed to cigarette smoke and in vitro to CSE, CD40 expressions noticeably escalated on the surfaces of BMDCs. The presence of Th17 cells, IL-17A, and IL-27 in the lung tissues prominently increased in mice exposed to cigarette smoke. The in vitro culture of CD4⁺ T cells and BMDCs significantly enhanced the differentiation of CD4⁺ T cells toward Th17 cells and secretions of IL-17A and IL-27 in the case that BMDCs were produced from mice exposed to cigarette smoke or the culture occurred in the presence of CSE. Usage of antagonistic CD40 antibody evidently reduced the number of Th17 cells, IL-17A, and IL-27 that increased due to cigarette smoke exposure.

Conclusion

The CD40–CD40L ligation is associated with the quantities of Th17 cells and relevant cytokines in the context of cigarette smoke exposure. Reducing the number of Th17 cells via the usage of antagonistic CD40 antibody can be an inspiration for pursuing a novel therapeutic target for immune inflammation in COPD.

Cigarette smoke-induced inflammation: NLRP10-mediated mechanisms

Chronic obstructive pulmonary disease (COPD) is a progressive, life-threatening disease that causes irreversible lung damage. Cigarette smoking is the chief etiologic factor for the commencement of this condition. Despite constant efforts to develop therapeutic interventions and to ascertain the molecular mechanism leading to the pathophysiology of this disease, much remains unknown. However, pattern recognition receptors (PRRs), i.e., Toll-like-receptors (TLRs) and NOD-like receptors (NLRs) are believed to play important roles in COPD and could serve as effective therapeutic targets. Although the role of TLRs in COPD has been well studied, the importance of NLRs has not yet been explored in detail. The NLR family member NLRP10 (aka NOD8, PAN5, PYNOD) is the only member of this family of proteins that lacks the leucine rich repeat (LRR) domain responsible for detection of pathogen and danger-associated molecular patterns (PAMPs/DAMPs). Therefore, instead of functioning as a PRR, NLRP10 may have a broader regulatory role. To elucidate the role of NLRP10 in secondhand smoke (SHS)-induced inflammation, we exposed C57Bl/6 (WT) and Nlrp10-deficient mice (Nlrp10^-/-) on the C57Bl/6 background to filtered air- or SHS- for 6 weeks (acute exposure) and assessed the resulting molecular events. Leukocyte recruitment in SHS-exposed Nlrp10^-/- mice was found to be significantly lower compared to SHS-exposed WT mice. In addition, we observed an important role for NLRP10 in SHS-mediated caspase-1 activation, cytokine/chemokine production (IL-1β, IL-18, MCP-1 and IL-17A), and induction of NF-κB and MAPKs in the lungs of C57Bl/6 mice. The reduced influx of CD4⁺IL-17A⁺ and CD8⁺IL-17A⁺ cells into the lungs of SHS-exposed Nlrp10^-/- mice and impaired differentiation of Nlrp10^-/- Th0 cells into Th17 cells (ex vivo) provide insight into the mechanistic details underlying NLRP10-dependent IL-17 production. We further substantiated our in vivo findings by challenging human alveolar type II epithelial cells (A549) transfected with scrambled- or Nlrp10-siRNA with cigarette smoke extract (CSE). We observed an important role of NLRP10 in cytokine and chemokine production as well as expression of NF-κB and MAPKs in CSE-exposed A549 cells. Furthermore, replenishment of A549 cell culture with recombinant IL-17A (rIL-17A) during NLRP10 knockdown rescued CSE-induced inflammatory responses. To identify upstream mediators of NLRP10 regulation we investigated epigenetic markers within the Nlrp10 promoter following cigarette smoke exposure and observed significant changes in active as well as repressive gene markers on histone 3 and histone 4 using both in vivo and in vitro study models. Further, alterations in the respective histone acetyl- and methyltransferases (PCAF, SET1, ESET, SUV20H1) correlated well with the observed histone modifications. Overall, our findings suggest a novel role of epigenetically regulated NLRP10 in Th17/IL-17 signaling during CS exposure.

Elastin receptor (S-gal) occupancy by elastin peptides modulates T-cell response during murine emphysema

Chronic obstructive pulmonary disease and emphysema are associated with increased elastin peptides (EP) production because of excessive breakdown of lung connective tissue. We recently reported that exposure of mice to EP elicited hallmark features of emphysema. EP effects are largely mediated through a receptor complex that includes the elastin-binding protein spliced-galactosidase (S-gal). In previous studies, we established a correlation between cytokine production and S-gal protein expression in EP-treated immune cells. In this study, we investigated the S-gal-dependent EP effects on T-helper (Th) and T-cytotoxic (Tc) responses during murine EP-triggered pulmonary inflammation. C57BL/6J mice were endotracheally instilled with the valine-glycine-valine-alanine-proline-glycine (VGVAPG) elastin peptide, and, 21 days after treatment, local and systemic T-lymphocyte phenotypes were analyzed at cytokine and transcription factor expression levels by multicolor flow cytometry. Exposure of mice to the VGVAPG peptide resulted in a significant increase in the proportion of the CD4+ and CD8+ T cells expressing the cytokines IFN-γ or IL-17a and the transcription factors T-box expressed in T cells or retinoic acid-related orphan receptor-γt (RORγt) without effects on IL-4 and Gata-binding protein 3 to DNA sequence [A/T]GATA[A/G] expression. These effects were maximized when each T-cell subpopulation was challenged ex vivo with EP, and they were inhibited in vivo when an analogous peptide antagonizing the EP/S-gal interactions was instilled together with the VGVAPG peptide. This study demonstrates that, during murine emphysema, EP-S-gal interactions contribute to a Th-1 and Th-17 proinflammatory T-cell response combined with a Tc-1 response. Our study also highlights the S-gal receptor as a putative pharmacological target to modulate such an immune response.

Microbiota Promotes Chronic Pulmonary Inflammation by Enhancing IL-17A and Autoantibodies

RATIONALE

Changes in the pulmonary microbiota are associated with progressive respiratory diseases including chronic obstructive pulmonary disease (COPD). Whether there is a causal relationship between these changes and disease progression remains unknown.

OBJECTIVES

To investigate the link between an altered microbiota and disease, we used a murine model of chronic lung inflammation that is characterized by key pathological features found in COPD and compared responses in specific pathogen-free (SPF) mice and mice depleted of microbiota by antibiotic treatment or devoid of a microbiota (axenic).

METHODS

Mice were challenged with LPS/elastase intranasally over 4 weeks, resulting in a chronically inflamed and damaged lung. The ensuing cellular infiltration, histological damage, and decline in lung function were quantified.

MEASUREMENTS AND MAIN RESULTS

Similar to human disease, the composition of the pulmonary microbiota was altered in diseased animals. We found that the microbiota richness and diversity were decreased in LPS/elastase-treated mice, with an increased representation of the genera Pseudomonas and Lactobacillus and a reduction in Prevotella. Moreover, the microbiota was implicated in disease development as mice depleted, or devoid, of microbiota exhibited an improvement in lung function, reduced inflammation, and lymphoid neogenesis. The absence of microbial cues markedly decreased the production of IL-17A, whereas intranasal transfer of fluid enriched with the pulmonary microbiota isolated from diseased mice enhanced IL-17A production in the lungs of antibiotic-treated or axenic recipients. Finally, in mice harboring a microbiota, neutralizing IL-17A dampened inflammation and restored lung function.

CONCLUSIONS

Collectively, our data indicate that host-microbial cross-talk promotes inflammation and could underlie the chronicity of inflammatory lung diseases.

Cigarette Smoke and DNA Cleavage Promote Lung Inflammation and Emphysema

Smoking-related lung diseases are among the most preventable and incurable ailments in the world. Smokers are at increased risk of developing chronic obstructive pulmonary disease that can be further complicated by emphysema and lung cancer. A subset of former smokers shows persistent lung inflammation and progressive loss of lung function, indicating a role for activation of acquired immunity in smoking-induced lung diseases. In addition to the well-established noxious effects of volatile compounds in cigarette smoke, incomplete combustion of tobacco generates nano-sized carbon black (nCB) that accumulate in lung myeloid dendritic cells and macrophages. Experimentally, intra-nasal instillation nCB can cause airway inflammation and emphysema in mice, underscoring their pathogenic role in inflammatory lung diseases. High throughput analyses of macrophages that have engulfed nCB reveal de novo activation of DNA repair enzymes, and histological studies provide evidence for DNA double-stranded breaks. Emphysematous lung myeloid dendritic cells that contain nCB express pro-inflammatory cytokines, and can efficiently differentiate naive CD4 T cells to interferon-g-secreting T helper 1 and interleukin 17A expressing cell subsets. Together these findings indicate that nCB accumulation in lung innate immune cells can initiate and sustain lung inflammation and promote emphysema development.

The Role of Mitochondria and Oxidative/Antioxidative Imbalance in Pathobiology of Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is a common preventable and treatable disease, characterized by persistent airflow limitation that is usually progressive and associated with an enhanced chronic inflammatory response in the airways and the lung to noxious particles or gases. The major risk factor of COPD, which has been proven in many studies, is the exposure to cigarette smoke. However, it is 15-20% of all smokers who develop COPD. This is why we should recognize the pathobiology of COPD as involving a complex interaction between several factors, including genetic vulnerability. Oxidant-antioxidant imbalance is recognized as one of the significant factors in COPD pathogenesis. Numerous exogenous and endogenous sources of ROS are present in pathobiology of COPD. One of endogenous sources of ROS is mitochondria. Although leakage of electrons from electron transport chain and forming of ROS are the effect of physiological functioning of mitochondria, there are various intra- and extracellular factors which may increase this amount and significantly contribute to oxidative-antioxidative imbalance. With the coexistence with impaired antioxidant defence, all these issues lead to oxidative and carbonyl stress. Both of these states play a significant role in pathobiology of COPD and may account for development of major comorbidities of this disease.

Severe Reduction in Number and Function of Peripheral T Cells Does Not Afford Protection toward Emphysema and Bronchial Remodeling Induced in Mice by Cigarette Smoke

The protein Lck (p56(Lck)) is a Src family tyrosine kinase expressed at all stages of thymocyte development and is required for maturation of T cells. The targeted disruption of Lck gene in mice results in severe block in thymocyte maturation with substantial reduction in the development of CD4(+)CD8(+) thymocytes, severe reduction of peripheral T cells, and disruption of T-cell receptor signaling with defective function of T-cell responses. To investigate the role of T lymphocyte in the development of cigarette smoke-induced pulmonary changes, Lck(-/-) mice and corresponding congenic wild-type mice were chronically exposed to cigarette smoke, and their lungs were analyzed by biochemical, immunologic, and morphometric methods. Smoking mice from both genotypes showed disseminated foci of emphysema and large areas of goblet cell metaplasia in bronchial and bronchiolar epithelium. Morphometric evaluation of lung changes and lung elastin determination confirmed that mice from both genotypes showed the same degree of emphysematous lesions. Thus, cigarette smoke exposure in the presence of severe reduction in number and function of peripheral T cells does not influence the development of pulmonary changes induced by cigarette smoke. The data obtained suggest that innate immunity is a leading actor in the early development of pulmonary changes in smoking mice and that the adaptive immune response may play a role at later stages.

Cigarette smoke represses the innate immune response to asbestos

Both cigarette smoke (CS) and asbestos cause lung inflammation and lung cancer, and at high asbestos exposure levels, populations exposed to both of these carcinogens display a synergistic increase in the development of lung cancer. The mechanisms through which these two toxic agents interact to promote lung tumorigenesis are poorly understood. Here, we begin to dissect the inflammatory signals induced by asbestos in combination with CS using a rodent inhalation model and in vitro cell culture. Wild‐type C57BL/6 mice were exposed to room air as a control, CS, and/or asbestos (4 days per week to CS and 1 day per week to asbestos for 5 weeks). Bronchoalveolar lavage (BAL) fluid was collected following exposure and analyzed for inflammatory mediators. Asbestos‐exposed mice displayed an increased innate immune response consistent with NLRP3 inflammasome activation. Compared to mice exposed only to asbestos, animals coexposed to CS + asbestos displayed attenuated levels of innate immune mediators and altered inflammatory cell recruitment. Histopathological changes in CS + asbestos‐exposed mice correlated with attenuated fibroproliferative lesion development relative to their counterparts exposed only to asbestos. In vitro experiments using a human monocyte cell line (THP‐1 cells) supported the in vivo results in that coexposure to cigarette smoke extract repressed NLRP3 inflammasome markers in cells treated with asbestos. These observations indicate that CS represses central components of the innate immune response to inhaled asbestos.

SF3B1 mutant MDS-initiating cells may arise from the haematopoietic stem cell compartment

Despite the recent evidence of the existence of myelodysplastic syndrome (MDS) stem cells in 5q-MDS patients, it is unclear whether haematopoietic stem cells (HSCs) could also be the initiating cells in other MDS subgroups. Here we demonstrate that SF3B1 mutation(s) in our cohort of MDS patients with ring sideroblasts can arise from CD34(+)CD38(-)CD45RA(-)CD90(+)CD49f(+) HSCs and is an initiating event in disease pathogenesis. Xenotransplantation of SF3B1 mutant HSCs leads to persistent long-term engraftment restricted to myeloid lineage. Moreover, genetically diverse evolving subclones of mutant SF3B1 exist in mice, indicating a branching multi-clonal as well as ancestral evolutionary paradigm. Subclonal evolution in mice is also seen in the clinical evolution in patients. Sequential sample analysis shows clonal evolution and selection of the malignant driving clone leading to AML transformation. In conclusion, our data show SF3B1 mutations can propagate from HSCs to myeloid progeny, therefore providing a therapeutic target.

Nanoparticulate carbon black in cigarette smoke induces DNA cleavage and Th17-mediated emphysema

Chronic inhalation of cigarette smoke is the major cause of sterile inflammation and pulmonary emphysema. The effect of carbon black (CB), a universal constituent of smoke derived from the incomplete combustion of organic material, in smokers and non-smokers is less known. In this study, we show that insoluble nanoparticulate carbon black (nCB) accumulates in human myeloid dendritic cells (mDCs) from emphysematous lung and in CD11c⁺ lung antigen presenting cells (APC) of mice exposed to smoke. Likewise, nCB intranasal administration induced emphysema in mouse lungs. Delivered by smoking or intranasally, nCB persisted indefinitely in mouse lung, activated lung APCs, and promoted T helper 17 cell differentiation through double-stranded DNA break (DSB) and ASC-mediated inflammasome assembly in phagocytes. Increasing the polarity or size of CB mitigated many adverse effects. Thus, nCB causes sterile inflammation, DSB, and emphysema and explains adverse health outcomes seen in smokers while implicating the dangers of nCB exposure in non-smokers.

DOI:http://dx.doi.org/10.7554/eLife.09623.001

Smoking for many years damages the lungs and leads to a disease called emphysema that makes it difficult to breathe and is often deadly. There are thousands of chemicals in cigarette smoke and many of them have been linked to the development of lung cancer, although it has been difficult to pinpoint those that are responsible for smoking-related emphysema. Moreover, cigarette smoke also contains large numbers of small particles and relatively little is known about the role played by these particles in smoking-related disease.

One of the hallmarks of long-term smoking is a blackening of the lung tissue that persists even if someone stops smoking. Previously, little was known about the composition of the substance that causes this blackening, or its significance in the development of emphysema. Now, by studying lung tissue taken from smokers with emphysema, You et al. have shown that this black substance is made of nano-sized particles of a material called carbon black (which is also known as elemental carbon). These nanoparticles are produced by the incomplete combustion of the cigarettes. You et al. also confirmed that nanoparticles of carbon black can cause emphysema in mice.

Closer examination of the lung damage caused by the nanoparticles revealed that they trigger breakages in DNA, which leads to inflammation of the lung. And because the nanoparticles cannot be cleared, they are released into the lung when cells die, which perpetuates lung inflammation and damage.

You et al. then went on to show that nanoparticles of carbon black can be modified in a way that allows them to be cleared from the lungs. Such modifications could potentially protect people who are exposed to carbon black nanoparticles in the environment or in workplaces where carbon black is used, such as factories that produce automobile tires and other rubber products.

DOI:http://dx.doi.org/10.7554/eLife.09623.002

Activation of C3a receptor is required in cigarette smoke-mediated emphysema

Exposure to cigarette smoke can initiate sterile inflammatory responses in the lung and activate myeloid dendritic cells (mDCs) that induce differentiation of T helper type 1 (Th1) and Th17 cells in the emphysematous lungs. Consumption of complement proteins increases in acute inflammation, but the contribution of complement protein 3 (C3) to chronic cigarette smoke-induced immune responses in the lung is not clear. Here, we show that following chronic exposure to cigarette smoke, C3-deficient (C3(-/-)) mice develop less emphysema and have fewer CD11b(+)CD11c(+) mDCs infiltrating the lungs as compared with wild-type mice. Proteolytic cleavage of C3 by neutrophil elastase releases C3a, which in turn increases the expression of its receptor (C3aR) on lung mDCs. Mice deficient in the C3aR (C3ar(-/-)) partially phenocopy the attenuated responses to chronic smoke observed in C3(-/-) mice. Consistent with a role for C3 in emphysema, C3 and its active fragments are deposited on the lung tissue of smokers with emphysema, and smoke-exposed mice. Together, these findings suggest a critical role for C3a through autocrine/paracrine induction of C3aR in the pathogenesis of cigarette smoke-induced sterile inflammation and provide new therapeutic targets for the treatment of emphysema.

Timely blockade of ICAM-1.LFA-1 interaction prevents disease onset in a mouse model of emphysema

AIM

It is becoming apparent that emphysema is partly driven by self-reactive T cells inducing inflammatory damage. Thus, T cells become targets for therapy similar to other autoimmune diseases. Costimulatory blockade therapy targets disease-specific T cells, rendering them ineffective by blocking a necessary costimulatory event on the T-cell surface. This therapy is tested here in mouse emphysema.

MATERIALS & METHODS

Peptides representing contact domains of counter receptors LFA-1 and ICAM-1 were used as blockade therapy in elastase-induced emphysema.

RESULTS

When administered during the first week after disease induction, blockade prevented lung destruction, reduced leukocyte infiltration and inhibited the decrease in T-cell CD4:CD8 ratio, also common in human emphysema.

CONCLUSION

Costimulatory blockade therapy can affect the progress of emphysema.

Novel aspects of pathogenesis and regeneration mechanisms in COPD

Chronic obstructive pulmonary disease (COPD), a major cause of death and morbidity worldwide, is characterized by expiratory airflow limitation that is not fully reversible, deregulated chronic inflammation, and emphysematous destruction of the lungs. Despite the fact that COPD is a steadily growing global healthcare problem, the conventional therapies remain palliative, and regenerative approaches for disease management are not available yet. We aim to provide an overview of key reviews, experimental, and clinical studies addressing lung emphysema development and repair mechanisms published in the past decade. Novel aspects discussed herein include integral revision of the literature focused on lung microflora changes in COPD, autoimmune component of the disease, and environmental risk factors other than cigarette smoke. The time span of studies on COPD, including emphysema, chronic bronchitis, and asthmatic bronchitis, covers almost 200 years, and several crucial mechanisms of COPD pathogenesis are described and studied. However, we still lack the holistic understanding of COPD development and the exact picture of the time-course and interplay of the events during stable, exacerbated, corticosteroid-treated COPD states, and transitions in-between. Several generally recognized mechanisms will be discussed shortly herein, ie, unregulated inflammation, proteolysis/antiproteolysis imbalance, and destroyed repair mechanisms, while novel topics such as deviated microbiota, air pollutants-related damage, and autoimmune process within the lung tissue will be discussed more extensively. Considerable influx of new data from the clinic, in vivo and in vitro studies stimulate to search for novel concise explanation and holistic understanding of COPD nowadays.

Different profiles of notch signaling in cigarette smoke-induced pulmonary emphysema and bleomycin-induced pulmonary fibrosis

OBJECTIVE

Different profiles of Notch signaling mediate naive T cell differentiation which might be involved in pulmonary emphysema and fibrosis.

METHODS

C57BL/6 mice were randomized into cigarette smoke (CS) exposure, bleomycin (BLM) exposure, and two separate groups of control for sham exposure to CS or BLM. The paratracheal lymph nodes of the animals were analyzed by real-time PCR and immunohistochemistry. Morphometry of the lung parenchyma, measurement of the cytokines, and cytometry of the bronchoalveolar lavage fluid (BALF) were also done accordingly.

RESULTS

In comparison with controls, all Notch receptors and ligands were upregulated by chronic CS exposure, especially Notch3 and DLL1 (P < 0.01), and this was in line with emphysema-like morphology and Th1-biased inflammation. While Notch3 and DLL1 were downregulated by BLM exposure (P < 0.01), those was in line with fibrotic lung remodeling and Th2 polarization.

CONCLUSIONS

This founding implies that the CS exposure but not the BLM exposure is capable of initiating Notch signaling in lymphoid tissue of the lung, which is likely relevant to the pathogenesis of pulmonary emphysema. Unable to initiate the Th1 response or inhibit it may lead to Th2 polarization and aberrant repair.

Haploinsufficiency of Hedgehog interacting protein causes increased emphysema induced by cigarette smoke through network rewiring

Background

The HHIP gene, encoding Hedgehog interacting protein, has been implicated in chronic obstructive pulmonary disease (COPD) by genome-wide association studies (GWAS), and our subsequent studies identified a functional upstream genetic variant that decreased HHIP transcription. However, little is known about how HHIP contributes to COPD pathogenesis.

Methods

We exposed Hhip haploinsufficient mice (Hhip^+/-) to cigarette smoke (CS) for 6 months to model the biological consequences caused by CS in human COPD risk-allele carriers at the HHIP locus. Gene expression profiling in murine lungs was performed followed by an integrative network inference analysis, PANDA (Passing Attributes between Networks for Data Assimilation) analysis.

Results

We detected more severe airspace enlargement in Hhip^+/- mice vs. wild-type littermates (Hhip^+/+) exposed to CS. Gene expression profiling in murine lungs suggested enhanced lymphocyte activation pathways in CS-exposed Hhip^+/- vs. Hhip^+/+ mice, which was supported by increased numbers of lymphoid aggregates and enhanced activation of CD8+ T cells after CS-exposure in the lungs of Hhip^+/-mice compared to Hhip^+/+ mice. Mechanistically, results from PANDA network analysis suggested a rewired and dampened Klf4 signaling network in Hhip^+/- mice after CS exposure.

Conclusions

In summary, HHIP haploinsufficiency exaggerated CS-induced airspace enlargement, which models CS-induced emphysema in human smokers carrying COPD risk alleles at the HHIP locus. Network modeling suggested rewired lymphocyte activation signaling circuits in the HHIP haploinsufficiency state.

Electronic supplementary material

The online version of this article (doi:10.1186/s13073-015-0137-3) contains supplementary material, which is available to authorized users.

Animal models of chronic obstructive pulmonary disease

Animal models of disease have always been welcomed by the scientific community because they provide an approach to the investigation of certain aspects of the disease in question. Animal models of COPD cannot reproduce the heterogeneity of the disease and usually only manage to represent the disease in its milder stages. Moreover, airflow obstruction, the variable that determines patient diagnosis, not always taken into account in the models. For this reason, models have focused on the development of emphysema, easily detectable by lung morphometry, and have disregarded other components of the disease, such as airway injury or associated vascular changes. Continuous, long-term exposure to cigarette smoke is considered the main risk factor for this disease, justifying the fact that the cigarette smoke exposure model is the most widely used. Some variations on this basic model, related to exposure time, the association of other inducers or inhibitors, exacerbations or the use of transgenic animals to facilitate the identification of pathogenic pathways have been developed. Some variations or heterogeneity of this disease, then, can be reproduced and models can be designed for resolving researchers' questions on disease identification or treatment responses.

Animal models of chronic obstructive pulmonary disease

INTRODUCTION

Chronic obstructive pulmonary disease (COPD) is a leading global cause of mortality and chronic morbidity. Inhalation of cigarette smoke is the principal risk factor for development of this disease. COPD is a progressive disease that is typically characterised by chronic pulmonary inflammation, mucus hypersecretion, airway remodelling and emphysema that collectively reduce lung function. There are currently no therapies that effectively halt or reverse disease progression. It is hoped that the development of animal models that develop the hallmark features of COPD, in a short time frame, will aid in the identifying and testing of new therapeutic approaches.

AREAS COVERED

The authors review the recent developments in mouse models of chronic cigarette smoke-induced COPD as well as the principal findings. Furthermore, the authors discuss the use of mouse models to understand the pathogenesis and the contribution of infectious exacerbations. They also discuss the investigations of the systemic co-morbidities of COPD (pulmonary hypertension, cachexia and osteoporosis).

EXPERT OPINION

Recent advances in the field mark a point where animal models recapitulate the pathologies of COPD patients in a short time frame. They also reveal novel insights into the pathogenesis and potential treatment of this debilitating disease.

TLR and NKG2D signaling pathways mediate CS-induced pulmonary pathologies

Long-term exposure to cigarette smoke (CS) can have deleterious effects on lung epithelial cells including cell death and the initiation of inflammatory responses. CS-induced cell injury can elaborate cell surface signals and cellular byproducts that stimulate immune system surveillance. Our previous work has shown that the expression of ligands for the cytotoxic lymphocyte activating receptor NKG2D is enhanced in patients with COPD and that the induction of these ligands in a mouse model can replicate COPD pathologies. Here, we extend these findings to demonstrate a role for the NKG2D receptor in CS-induced pathophysiology and provide evidence linking nucleic acid-sensing endosomal toll-like receptor (TLR) signaling to COPD pathology through NKG2D activation. Specifically, we show that mice deficient in NKG2D exhibit attenuated pulmonary inflammation and airspace enlargement in a model of CS-induced emphysema. Additionally, we show that CS exposure induces the release of free nucleic acids in the bronchoalveolar lavage and that direct exposure of mouse lung epithelial cells to cigarette smoke extract similarly induces functional nucleic acids as assessed by TLR3, 7, and 9 reporter cell lines. We demonstrate that exposure of mouse lung epithelial cells to TLR ligands stimulates the surface expression of RAET1, a ligand for NKG2D, and that mice deficient in TLR3/7/9 receptor signaling do not exhibit CS-induced NK cell hyperresponsiveness and airspace enlargement. The findings indicate that CS-induced airway injury stimulates TLR signaling by endogenous nucleic acids leading to elevated NKG2D ligand expression. Activation of these pathways plays a major role in the altered NK cell function, pulmonary inflammation and remodeling related to long-term CS exposure.

Tobacco smoke induced COPD/emphysema in the animal model-are we all on the same page?

Chronic Obstructive Pulmonary Disease (COPD) is one of the foremost causes of death worldwide. It is primarily caused by tobacco smoke, making it an easily preventable disease, but facilitated by genetic α-1 antitrypsin deficiency. In addition to active smokers, health problems also occur in people involuntarily exposed to second hand smoke (SHS). Currently, the relationship between SHS and COPD is not well established. Knowledge of pathogenic mechanisms is limited, thereby halting the advancement of new treatments for this socially and economically detrimental disease. Here, we attempt to summarize tobacco smoke studies undertaken in animal models, applying both mainstream (direct, nose only) and side stream (indirect, whole body) smoke exposures. This overview of 155 studies compares cellular and molecular mechanisms as well as proteolytic, inflammatory, and vasoreactive responses underlying COPD development. This is a difficult task, as listing of exposure parameters is limited for most experiments. We show that both mainstream and SHS studies largely present similar inflammatory cell populations dominated by macrophages as well as elevated chemokine/cytokine levels, such as TNF-α. Additionally, SHS, like mainstream smoke, has been shown to cause vascular remodeling and neutrophil elastase-mediated proteolytic matrix breakdown with failure to repair. Disease mechanisms and therapeutic interventions appear to coincide in both exposure scenarios. One of the more widely applied interventions, the anti-oxidant therapy, is successful for both mainstream and SHS. The comparison of direct with indirect smoke exposure studies in this review emphasizes that, even though there are many overlapping pathways, it is not conclusive that SHS is using exactly the same mechanisms as direct smoke in COPD pathogenesis, but should be considered a preventable health risk. Some characteristics and therapeutic alternatives uniquely exist in SHS-related COPD.