XCL1 enhances regulatory activities of CD4+ CD25(high) CD127(low/-) T cells in human allergic asthma

Single-cell profiling of bronchoalveolar cells reveals a Th17 signature in neutrophilic severe equine asthma

Severe equine asthma (SEA) is a complex respiratory condition characterized by chronic airway inflammation. It shares many clinical and pathological features with human neutrophilic asthma, making it a valuable model for studying this condition. However, the immune mechanisms driving SEA have remained elusive. Although SEA has been primarily associated with a Th2 response, there have also been reports of Th1, Th17, or mixed-mediated responses. To uncover the elusive immune mechanisms driving SEA, we performed single-cell mRNA sequencing (scRNA-seq) on cryopreserved bronchoalveolar cells from 11 Warmblood horses, 5 controls and 6 with SEA. We identified six major cell types, including B cells, T cells, monocytes-macrophages, dendritic cells, neutrophils, and mast cells. All cell types exhibited significant heterogeneity, with previously identified and novel cell subtypes. Notably, we observed monocyte-lymphocyte complexes and detected a robust Th17 signature in SEA, with CXCL13 upregulation in intermediate monocytes. Asthmatic horses exhibited expansion of the B-cell population, Th17 polarization of the T-cell populations, and dysregulation of genes associated with T-cell function. Neutrophils demonstrated enhanced migratory capacity and heightened aptitude for neutrophil extracellular trap formation. These findings provide compelling evidence for a predominant Th17 immune response in neutrophilic SEA, driven by dysregulation of monocyte and T-cell genes. The dysregulated genes identified through scRNA-seq have potential as biomarkers and therapeutic targets for SEA and provide insights into human neutrophilic asthma.

Anti-metabolic agent pegaspargase plus PD-1 antibody sintilimab for first-line treatment in advanced natural killer T cell lymphoma

Natural killer T cell lymphoma (NKTCL) is highly aggressive, with advanced stage patients poorly responding to intensive chemotherapy. To explore effective and safe treatment for newly diagnosed advanced stage NKTCL, we conducted a phase II study of anti-metabolic agent pegaspargase plus PD-1 antibody sintilimab (NCT04096690). Twenty-two patients with a median age of 51 years (range, 24-74) were enrolled and treated with induction treatment of pegaspargase 2500 IU/m2 intramuscularly on day 1 and sintilimab 200 mg intravenously on day 2 for 6 cycles of 21 days, followed by maintenance treatment of sintilimab 200 mg for 28 cycles of 21 days. The complete response and overall response rate after induction treatment were 59% (95%CI, 43-79%) and 68% (95%CI, 47-84%), respectively. With a median follow-up of 30 months, the 2 year progression-free and overall survival rates were 68% (95%CI, 45-83%) and 86% (95%CI, 63-95%), respectively. The most frequently grade 3/4 adverse events were neutropenia (32%, n = 7) and hypofibrinogenemia (18%, n = 4), which were manageable and led to no discontinuation of treatment. Tumor proportion score of PD-L1, peripheral blood high-density lipoprotein cholesterol, and apolipoprotein A-I correlated with good response, while PD-1 on tumor infiltrating lymphocytes and peripheral Treg cells with poor response to pegaspargase plus sintilimab treatment. In conclusion, the chemo-free regimen pegaspargase plus sintilimab was effective and safe in newly diagnosed, advanced stage NKTCL. Dysregulated lipid profile and immunosuppressive signature contributed to treatment resistance, providing an alternative therapeutic approach dual targeting fatty acid metabolism and CTLA-4 in NKTCL.

Different Transcriptome Features of Peripheral Blood Mononuclear Cells in Non-Emphysematous Chronic Obstructive Pulmonary Disease

Non-emphysematous chronic obstructive pulmonary disease (COPD), which is defined based on chest computed tomography findings, presented different transcriptome features of peripheral blood mononuclear cells (PBMCs) compared with emphysematous COPD. Enrichment analysis of transcriptomic data in COPD demonstrated that the "Hematopoietic cell lineage" pathway in Kyoto Encyclopedia of Genes and Genomes pathway analysis was highly upregulated, suggesting that cellular dynamic dysregulation in COPD lungs is affected by pathologically modified PBMCs. The differentially expressed genes (DEGs) upregulated in PBMCs reflected the disease state of non-emphysematous COPD. Upregulated DEGs such as XCL1, PRKCZ, TMEM102, CD200R1, and AQP1 activate T lymphocytes and eosinophils. Upregulating keratan sulfate biosynthesis and metabolic processes is associated with protection against the destruction of the distal airways. ITGA3 upregulation augments interactions with extracellular matrix proteins, and COL6A1 augments the profibrotic mast cell phenotype during alveolar collagen VI deposition. Upregulating HSPG2, PDGFRB, and PAK4 contributes to the thickening of the airway wall, and upregulating SERPINF1 expression explains the better-preserved vascular bed. Therefore, gene expression and pathway analysis in PBMCs in patients with non-emphysematous COPD represented type 2 immune responses and airway remodeling features. Therefore, these patients have asthmatic potential despite no clinical signs of asthma, in contrast to those with emphysematous COPD.

Conventional type I migratory CD103+ dendritic cells are required for corneal allograft survival

Corneal transplant rejection primarily occurs because of the T helper 1 (Th1) effector cell-mediated immune response of the host towards allogeneic tissue. The evidence suggests that type 1 migratory conventional CD103+ dendritic cells (CD103+DC1) acquire an immunosuppressive phenotype in the tumor environment; however, the involvement of CD103+DC1 in allograft survival continues to be an elusive question of great clinical significance in tissue transplantation. In this study, we assess the role of CD103+DC1 in suppressing Th1 alloreactivity against transplanted corneal allografts. The immunosuppressive function of CD103+DC1 has been extensively studied in non-transplantation settings. We found that host CD103+DC1 infiltrates the corneal graft and migrates to the draining lymph nodes to suppress alloreactive CD4+ Th1 cells via the programmed death-ligand 1 axis. The systemic depletion of CD103+ DC1 in allograft recipients leads to amplified Th1 activation, impaired Treg function, and increased rate of allograft rejection. Although allograft recipient Rag1 null mice reconstituted with naïve CD4+CD25- T cells efficiently generated peripheral Treg cells (pTreg), the CD103+DC1-depleted mice failed to generate pTreg. Furthermore, adoptive transfer of pTreg failed to rescue allografts in CD103+DC1-depleted recipients from rejection. These data demonstrate the critical role of CD103+DC1 in regulating host alloimmune responses.

3DFAACTS-SNP: using regulatory T cell-specific epigenomics data to uncover candidate mechanisms of type 1 diabetes (T1D) risk

Background

Genome-wide association studies (GWAS) have enabled the discovery of single nucleotide polymorphisms (SNPs) that are significantly associated with many autoimmune diseases including type 1 diabetes (T1D). However, many of the identified variants lie in non-coding regions, limiting the identification of mechanisms that contribute to autoimmune disease progression. To address this problem, we developed a variant filtering workflow called 3DFAACTS-SNP to link genetic variants to target genes in a cell-specific manner. Here, we use 3DFAACTS-SNP to identify candidate SNPs and target genes associated with the loss of immune tolerance in regulatory T cells (Treg) in T1D.

Results

Using 3DFAACTS-SNP, we identified from a list of 1228 previously fine-mapped variants, 36 SNPs with plausible Treg-specific mechanisms of action. The integration of cell type-specific chromosome conformation capture data in 3DFAACTS-SNP identified 266 regulatory regions and 47 candidate target genes that interact with these variant-containing regions in Treg cells. We further demonstrated the utility of the workflow by applying it to three other SNP autoimmune datasets, identifying 16 Treg-centric candidate variants and 60 interacting genes. Finally, we demonstrate the broad utility of 3DFAACTS-SNP for functional annotation of all known common (> 10% allele frequency) variants from the Genome Aggregation Database (gnomAD). We identified 9376 candidate variants and 4968 candidate target genes, generating a list of potential sites for future T1D or other autoimmune disease research.

Conclusions

We demonstrate that it is possible to further prioritise variants that contribute to T1D based on regulatory function, and illustrate the power of using cell type-specific multi-omics datasets to determine disease mechanisms. Our workflow can be customised to any cell type for which the individual datasets for functional annotation have been generated, giving broad applicability and utility.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13072-022-00456-5.

Can the biomolecular corona induce an allergic reaction?-A proof-of-concept study

Ferumoxytol nanoparticles are being used clinically for the treatment of anemia and molecular imaging in patients. It is well documented that while most patients tolerate ferumoxytol well, a small percentage of patients (i.e., 0.01%) develop severe allergic reactions. The purpose of our proof-of-concept study was to determine whether patients with or without hypersensitivity reactions have specific protein corona profiles around ferumoxytol nanoparticles. In a retrospective, institutional review board approved pilot study, we enrolled 13 pediatric patients (5 girls, 8 boys, mean age 16.9 ± 8.2 years) who received a ferumoxytol-enhanced magnetic resonance imaging and who did (group 1, n = 5) or did not (group 2, n = 8) develop an allergic reaction. Blood samples of these patients were incubated with ferumoxytol, and the formation of a hard protein corona around ferumoxytol nanoparticles was measured by dynamic light scattering, zeta potential, and liquid chromatography-mass spectrometry. We also performed in vitro immune response analyses to randomly selected coronas from each group. Our results provide preliminary evidence that ex vivo analysis of the biomolecular corona may provide useful and predictive information on the possibility of severe allergic reactions to ferumoxytol nanoparticles. In the future, patients with predisposition of an allergic reaction to ferumoxytol may be diagnosed based on the proteomic patterns of the corona around ferumoxytol in their blood sample.

Traumatic brain injury in mice induces changes in the expression of the XCL1/XCR1 and XCL1/ITGA9 axes

Background

Every year, millions of people suffer from various forms of traumatic brain injury (TBI), and new approaches with therapeutic potential are required. Although chemokines are known to be involved in brain injury, the importance of X-C motif chemokine ligand 1 (XCL1) and its receptors, X-C motif chemokine receptor 1 (XCR1) and alpha-9 integrin (ITGA9), in the progression of TBI remain unknown.

Methods

Using RT-qPCR/Western blot/ELISA techniques, changes in the mRNA/protein levels of XCL1 and its two receptors, in brain areas at different time points were measured in a mouse model of TBI. Moreover, their cellular origin and possible changes in expression were evaluated in primary glial cell cultures.

Results

Studies revealed the spatiotemporal upregulation of the mRNA expression of XCL1, XCR1 and ITGA9 in all the examined brain areas (cortex, thalamus, and hippocampus) and at most of the evaluated stages after brain injury (24 h; 4, 7 days; 2, 5 weeks), except for ITGA9 in the thalamus. Moreover, changes in XCL1 protein levels occurred in all the studied brain structures; the strongest upregulation was observed 24 h after trauma. Our in vitro experiments proved that primary murine microglial and astroglial cells expressed XCR1 and ITGA9, however they seemed not to be a main source of XCL1.

Conclusions

These findings indicate that the XCL1/XCR1 and XCL1/ITGA9 axes may participate in the development of TBI. The XCL1 can be considered as one of the triggers of secondary injury, therefore XCR1 and ITGA9 may be important targets for pharmacological intervention after traumatic brain injury.

Graphic abstract

Artemisia Pollen Extracts Exposed to Diesel Exhaust Enhance Airway Inflammation and Immunological Imbalance in Asthmatic Mice Model

BACKGROUND

Vehicle-induced air pollution may increase the prevalence and severity of asthma. Pollens are important sources of outdoor allergens associated with asthma. Outdoor pollution may influence the structure of pollen grains, resulting in enhanced immune reactions.

OBJECTIVE

This study aims to investigate the impact that artemisia pollen extracts exposed to diesel emissions (APEDE) may induce - allergic airway inflammation, pulmonary pathology and immune imbalance - in mice.

METHODS

Sixty male Balb/c mice were equally randomized into 5 groups, sensitized with 30 μL artemisia pollen extracts (APE) or APEDE adsorbed on 2 mg aluminum hydroxide gel by intraperitoneal injection on day 0, 7, 14, and 22, and challenged intranasally once per day with 30 μL APE or APEDE from day 29 to 36. The controlling group used phosphate-buffered saline as control.

RESULTS

In mice immunized and challenged by APEDE, the clinical phenotype of eosinophils, neutrophils in bronchoalveolar lavage fluid (BALF), tracheal wall thickness, airway smooth muscle thickness and airway resistance increased significantly. Pathophysiological parameters such as interleukin (IL)-17A and tumour necrosis factor-α production in BALF and serum, and the ratio of Th17/Treg cells in CD4+ cells increased significantly, while IL-10 in BALF and serum and the ratio of Treg cells decreased significantly. It was further found that the expression of oxidative stress marker 3-nitrotyrosine (3-NT) and the activation of nuclear factor kappa B (NF-κB) were significantly increased. The correlation analysis showed that the expression of 3-NT was positively correlated with the activation of NF-κB.

CONCLUSION

Our findings suggested that pollens exposed to diesel exhaust enhance allergic responses, which may contribute to an increased prevalence of allergic diseases in urban environments with serious exhaust emissions.

Regulatory T Cells in Respiratory Health and Diseases

Respiratory diseases compromise the health of millions of people all over the world and are strongly linked to the immune dysfunction. CD4+FOXP3+ T regulatory cells, also known as Tregs, have a central role maintaining tissue homeostasis during immune responses. Their activity and clinical impact have been widely studied in different clinical conditions including autoimmune diseases, inflammatory conditions, and cancer, amongst others. Tregs express transcription factor forkhead box P3 (FOXP3), which allows regulation of the immune response through anti-inflammatory cytokines such as IL-10 or transforming growth factor beta (TGF-β) and direct cell-to-cell interaction. Maintenance of immune tolerance is achieved via modulation of effector CD4+ T helper 1, 2 or 17 (Th1, Th2, Th17) cells by Tregs. This review highlights the recent progress in the understanding of Tregs in different disorders of the respiratory system.

The invariant natural killer T cell-mediated chemokine X-C motif chemokine ligand 1-X-C motif chemokine receptor 1 axis promotes allergic airway hyperresponsiveness by recruiting CD103+ dendritic cells

BACKGROUND

The chemokine X-C motif chemokine ligand 1 (XCL1)-X-C motif chemokine receptor 1 (XCR1) axis has been reported to play a role in immune homeostasis and inflammation. However, it is not known whether this axis has a critical function in patients with allergic asthma.

OBJECTIVE

In the present study we explored whether the invariant natural killer T (iNKT) cell-mediated XCL1-XCR1 axis regulated allergic asthma.

METHODS

Ovalbumin (OVA)- or house dust mite-induced asthma was developed in XCL1 or XCR1 knockout (KO) mice.

RESULTS

XCL1 or XCR1 KO mice showed attenuation in airway hyperresponsiveness (AHR), numbers of CD103⁺ dendritic cells (DCs), and T_H2 responses in the lungs compared with wild-type (WT) mice during OVA- or house dust mite-induced asthma. These effects were reversed by intratracheal administration of recombinant XCL1 or adoptive transfer of CD103⁺ DCs but not CD11b⁺ DCs into XCL1 KO mice. Moreover, iNKT cells highly expressed XCL1 both in vitro and in vivo. On intranasal α-galactosyl ceramide challenge, CD103⁺ DC numbers in the lungs were increased in WT but not XCL1 KO mice. Furthermore, adoptive transfer of WT iNKT cells increased AHR, CD103⁺ DC recruitment, and T_H2 responses in the lungs of CD1d KO mice during OVA-induced asthma, whereas adoptive transfer of XCL1-deficient iNKT cells did not. In human patients, percentages and XCL1 production capacity of iNKT cells from PBMCs were greater in patients with asthma than in healthy control subjects.

CONCLUSION

These data demonstrate that the iNKT cell-mediated XCL1-XCR1 axis promotes AHR by recruiting CD103⁺ DCs into the lung in patients with allergic asthma.

Imbalance between Subpopulations of Regulatory T Cells in Patients with Acute Exacerbation of COPD

Human regulatory T cells (Tregs) have been reported to be not significantly different in the peripheral blood of patients with chronic obstructive pulmonary disease (COPD) and healthy controls. Recent research has identified some new markers for Tregs and indicated that Tregs are composed of distinct subpopulations. The aim of the study was to describe the changing patterns of circulating Treg subpopulations in patients with acute exacerbation of COPD (AECOPD) and healthy controls, and to explore their potential roles in AECOPD pathogenesis. Blood samples were obtained from 30 never-smokers with normal lung function and 30 patients with COPD before and after they had an exacerbation. The proportions of Treg subpopulations were evaluated using flow cytometry. In the peripheral blood, decreased proportions of CD4⁺CD25⁺CD127^low Tregs, CD4⁺CD25⁺CD45RA⁺ Tregs, and CD4⁺CD25⁺CD62L⁺ Tregs and an increased proportion of CD4⁺CD25⁺CD45RO⁺ Tregs were found in patients with stable COPD compared with non-smokers with normal lung function. The patients showed further changes in Treg subpopulations when they had an AECOPD, with an overall decrease in a suppressive subset, indicating that the immune negative regulatory population of Tregs did not play an effective role. Immune homeostasis favored inflammation, and a negative correlation between the circulating tumor necrosis factor-alpha and the proportions of CD4⁺CD25⁺CD62L⁺ cells (r = -0.698, p < 0.05) in patients with AECOPD was found. The imbalance between the suppressive subsets and the proinflammatory subset of Tregs and the decline of Treg subpopulations with immunosuppressive activity may play important roles in AECOPD progression.

A pilot study comparing T-regulatory cell function among healthy children in different areas of Gansu, China

Immune system is critical to protecting human health from toxic substances. Our previously published research had found an important link between polycyclic aromatic hydrocarbons (PAHs) in ambient air and changes at the DNA level in immune cells that led to impaired function of regulatory T (Treg) cells in children living in California, USA. But molecular and cellular pathways of these changes remain unclear. The present study aims to explore whether exposure to PAHs leads to changes in Treg cells functions of children living in Gansu, China, where ambient air pollution levels are much higher than those in California, and to explore potential mechanisms of PAH-induced immunological dysfunctions. Air pollutions in Lanzhou and Lintao, Gansu Province, were measured from December 2015 to June 2016. Healthy children were recruited from both cities and enrolled in this pilot study. Demographic information was collected by questionnaires. Blood samples were collected. Peripheral blood Treg cells were analyzed for Treg cells percentage by flow cytometry. Gene expression of forkhead box transcription factor 3 (Foxp3), transforming growth factor-β (TGF-β), and interleukin 35 (IL35) were examined by reverse transcription-polymerase chain reaction (RT-PCR). The results indicated PAH concentration (as sum of 16 PAHs) in Lintao was over two times higher than that was in Lanzhou (707 vs. 326 ng/m³), whereas PM_2.5 concentration was comparable in two cities (55.3 in Lintao vs. 65.7 μg/m³ in Lanzhou). Notably, we observed lower gene expressions for Foxp3 (P < 0.05), IL35 (P < 0.05), and TGF-β, in children living in Lintao, suggesting an impairment of Treg cells function potentially associated with higher PAH exposure in Lintao. However, no significant difference was observed in Treg cells % among CD4⁺ T cells between Lanzhou and Lintao groups.

Expanding Diversity and Common Goal of Regulatory T and B Cells. II: In Allergy, Malignancy, and Transplantation

Regulation of immune response was found to play an important role in the course of many diseases such as autoimmune diseases, allergy, malignancy, organ transplantation. The studies on immune regulation focus on the role of regulatory cells (Tregs, Bregs, regulatory myeloid cells) in these disorders. The number and function of Tregs may serve as a marker of disease activity. As in allergy, the depletion of Tregs is observed and the results of allergen-specific immunotherapy could be measured by an increase in the population of IL-10⁺ regulatory cells. On the basis of the knowledge of anti-cancer immune response regulation, new directions in therapy of tumors are introduced. As the proportion of regulatory cells is increased in the course of neoplasm, the therapeutic action is directed at their inhibition. The depletion of Tregs may be also achieved by an anti-check-point blockade, anti-CD25 agents, and inhibition of regulatory cell recruitment to the tumor site by affecting chemokine pathways. However, the possible favorable role of Tregs in cancer development is considered and the plasticity of immune regulation should be taken into account. The new promising direction of the treatment based on regulatory cells is the prevention of transplant rejection. A different way of production and implementation of classic Tregs as well as other cell types such as double-negative cells, Bregs, CD4⁺ Tr1 cells are tested in ongoing trials. On the basis of the results of current studies, we could show in this review the significance of therapies based on regulatory cells in different disorders.

The role of the chemokine receptor XCR1 in breast cancer cells

Considerable attention has recently been paid to the application of chemokines to cancer immunotherapy due to their complex role in cell proliferation, invasion, metastasis, and tumorigenesis, which extends beyond the regulation of lymphocyte migration during immune responses. The expression and the function of the chemokine receptor XCR1 on breast cancer have remained elusive to date. In this study, the expressions of XCR1 mRNA were tested by quantitative real-time polymerase chain reaction in one breast epithelial cell line (MCF-10A) and nine breast cancer cell lines (MDA-MB-231, 231HM, 231BO, MDA-MB-468, MCF-7, T47D, Bcap-37, ZR-75-30, and SK-BR-3). We established XCR1-overexpressing breast cancer cell line MDA-MB-231 (231/XCR1) in XCR1 low expression cell line MDA-MB-231 (231). The ability of proliferation, invasion, and metastasis was measured by CCK8, plate cloning formation, and transwell analysis, respectively, in XCR1-overexpressing breast cancer cell lines (231/XCR1) and their parental cell line MDA-MB-231/Vector (simplified as “231/Vector”); 5×10⁶/100 μL cells were inoculated in mammary fat pad of BALB/c nude mice. There were six BALB/c nude mice in the experimental group and control group. Protein expression was analyzed by cell immunofluorescence and Western blot. The growth of XCR1-overexpressing human breast cancer cell line MDA-MB-231 in vitro was restrained and tumorigenesis in vivo was also extenuated, its mechanism may involve in the inhibition of MAPK and PI3K/AKT/mTOR signaling pathway, but increase in LC3 expression. However, the overexpression of XCR1 in human breast cancer cell line MDA-MB-231 in vitro can promote the migration and invasion partially due to decreasing the protein level of β-catenin. Therefore, XCR1 can affect the biological characteristics of some special breast cancer cells through complex signal transduction pathway.

Progress in research on C-chemokine XCL1

XCL1, also known as lymphotactin, is the only known member of the C-type-chemokine family, which is produced mainly by CD8⁺ T cells and natural killer cells. XCL1 has a unique amino acid sequence feature and two interchangeable conformations, which makes XCL1 different from other chemokines in structure and function. The XCL1-specific receptor, XCR1, is a member of the G-protein-coupled receptor family and plays an important role in the negative selection of T cells in the thymus and in the initiation of cross-antigen presentation and mediation of cytotoxic immune responses. XCL1 can regulate the balance of the immune system and maintain intestinal immune homeostasis, and it is involved in a variety of diseases such as autoimmune diseases, nephritis, tuberculosis and human immunodeficiency virus infection. In recent years, the selective expression of XCR1 on CD8⁺ DCs with strong cross antigen-presention ability has been proved, which has led to studies using XCL1 for mucosal immunization, antitumor immunotherapy and targeted vaccine development.

Epigenetics: The New Frontier in the Landscape of Asthma

Over the years, on a global scale, asthma has continued to remain one of the leading causes of morbidity, irrespective of age, sex, or social bearings. This is despite the prevalence of varied therapeutic options to counter the pathogenesis of asthma. Asthma, as a disease per se, is a very complex one. Scientists all over the world have been trying to obtain a lucid understanding of the machinations behind asthma. This has led to many theories and conjectures. However, none of the scientific disciplines have been able to provide the missing links in the chain of asthma pathogenesis. This was until epigenetics stepped into the picture. Though epigenetic research in asthma is in its nascent stages, it has led to very exciting results, especially with regard to explaining the massive influence of environment on development of asthma and its varied phenotypes. However, there remains a lot of work to be done, especially with regard to understanding how the interactions between immune system, epigenome, and environment lead to asthma. But introduction of epigenetics has infused a fresh lease of life in research into asthma and the mood among the scientific community is that of cautious optimism.

T regulatory cell chemokine production mediates pathogenic T cell attraction and suppression

T regulatory cells (Tregs) control immune homeostasis by preventing inappropriate responses to self and nonharmful foreign antigens. Tregs use multiple mechanisms to control immune responses, all of which require these cells to be near their targets of suppression; however, it is not known how Treg-to-target proximity is controlled. Here, we found that Tregs attract CD4+ and CD8+ T cells by producing chemokines. Specifically, Tregs produced both CCL3 and CCL4 in response to stimulation, and production of these chemokines was critical for migration of target T cells, as Tregs from Ccl3-/- mice, which are also deficient for CCL4 production, did not promote migration. Moreover, CCR5 expression by target T cells was required for migration of these cells to supernatants conditioned by Tregs. Tregs deficient for expression of CCL3 and CCL4 were impaired in their ability to suppress experimental autoimmune encephalomyelitis or islet allograft rejection in murine models. Moreover, Tregs from subjects with established type 1 diabetes were impaired in their ability to produce CCL3 and CCL4. Together, these results demonstrate a previously unappreciated facet of Treg function and suggest that chemokine secretion by Tregs is a fundamental aspect of their therapeutic effect in autoimmunity and transplantation.

Differential expression of inflammation-related genes in IL-4 transgenic mice before and after the onset of atopic dermatitis skin lesions

IL-4 plays an important role in the pathogenesis of atopic dermatitis (AD), a common chronic inflammatory skin disease. We have generated IL-4 transgenic (Tg) mice by over-expressing IL-4 in the epidermis. These mice spontaneously develop chronic pruritic inflammatory skin lesions, which meet the clinical and histological diagnostic criteria for human AD. Systemic survey of immune-related genes in this mouse model, however, has not been performed. In this study, we utilize PCR array technique to examine hundreds of inflammation-related genes in the IL-4 Tg mice before and after the onset of skin lesions as well as in their wild type (WT) littermates. Only those genes with at least 2-fold up-regulation or down-regulation and with a P-value of less than 0.05 in comparison to WT controls were identified and analyzed. In the skin lesions, many chemokines, pro-inflammatory cytokines, and other AD-related factors are dysregulated compared to the wild type mice. Particularly, CXCL5, IL-1β, IL-24, IL-6, oncostatin M, PTGS2, FPR1 and REG3γ are up-regulated several hundred-fold. In the pre-lesional group that shows no obvious skin abnormality on clinical observation, 30 dysregulated genes are nevertheless identified though the fold changes are much less than that of the lesional group, including CCL6, CCL8, CCL11, CCL17, CXCL13, CXCL14, CXCR3 and IL-12Rβ2. Finally using ELISA, we demonstrate that 4 most dramatically up-regulated factors in the skin are also elevated in the peripheral blood of the IL-4 Tg mice. Taken together, our data have identified hundreds of dysregulated factors in the IL-4 Tg mice before and after the onset of skin lesions. Future detailed examination of these factors will shed light on our understanding of the development and progression of AD and help to discover important biomarkers for clinical AD diagnosis and treatment.

Integrating mitochondriomics in children's environmental health

The amount of scientific research linking environmental exposures and childhood health outcomes continues to grow; yet few studies have teased out the mechanisms involved in environmentally-induced diseases. Cells can respond to environmental stressors in many ways: inducing oxidative stress/inflammation, changes in energy production and epigenetic alterations. Mitochondria, tiny organelles that each retains their own DNA, are exquisitely sensitive to environmental insults and are thought to be central players in these pathways. While it is intuitive that mitochondria play an important role in disease processes, given that every cell of our body is dependent on energy metabolism, it is less clear how environmental exposures impact mitochondrial mechanisms that may lead to enhanced risk of disease. Many of the effects of the environment are initiated in utero and integrating mitochondriomics into children's environmental health studies is a critical priority. This review will highlight (i) the importance of exploring environmental mitochondriomics in children's environmental health, (ii) why environmental mitochondriomics is well suited to biomarker development in this context, and (iii) how molecular and epigenetic changes in mitochondria and mitochondrial DNA (mtDNA) may reflect exposures linked to childhood health outcomes.

The relative values of CD8+CD25+Foxp3brigh Treg cells correlate with selected lung function parameters in asthma

The study aimed to detect CD8(+)CD25(+)FoxP3(brigh) Tregs and investigate their possible association with selected lung function values. CD8(+)CD25(+)FoxP3(brigh) Tregs were detected by flow cytometry in the peripheral blood of 25 patients with severe asthma (SA), 25 patients with mild-to-moderate asthma (MA), and 25 age-matched healthy donors (NC). The percentages of CD8(+)CD25(+)FoxP3(brigh) Tregs of the patients with severe (3.4 ± 4.55), and mild-to-moderate asthma (7.5 ± 8.15), were markedly lower than those of controls (12.1 ± 13.2). The mean forced expiratory volume in 1 s (FEV1) % predicted value in severe asthma subpopulation was significantly lower (67.05 ± 15.98%) when compared with that of mild-to-moderate asthma subgroup (87.71 ± 16.12%). Interestingly, the percentages of CD8(+)CD25(+)FoxP3(brigh) Tregs correlate with mean peak expiratory flow (PEF)% predicted values in severe (r = 0.7, P <0.01) and mild-to-moderate (r = 0.73, P <0.01) asthma. In contrast, this parameter was positively correlated with FEV1% predicted values in the severe asthmatics only (r = 0.71, P <0.01). In summary, this study establishes a link between the percentage of CD8(+)CD25(+)FoxP3(brigh) Tregs and selected lung function parameters, suggesting that this parameter has potential as a marker for inflammation and airflow obstruction.

In utero arsenic exposure and fetal immune repertoire in a US pregnancy cohort

Arsenic has wide-ranging effects on human health and there is evidence that it alters the immune response by influencing CD4+/CD8+ T cell ratios, IL-2 cytokine levels, and the expression of immune-response genes. We investigated the impact of in utero environmental arsenic exposure on immune development and function in newborns participating in a pregnancy cohort in New Hampshire, U.S., where arsenic levels have exceeded the current EPA maximum contaminant level of 10 μg/L. Our results showed that maternal urinary arsenic concentrations were inversely related to absolute total CD45RA+ CD4+ cord blood CD69+ T cell counts (N=116, p=0.04) and positively associated with CD45RA+ CD69- CD294+ cell counts (p=0.01). In placental samples (N=70), higher in utero urinary arsenic concentrations were positively associated with the expression of IL1β (p=0.03). These data provide evidence that relatively low-level arsenic exposure in utero may alter the fetal immune system and lead to immune dysregulation.

Cytokines and chemokines: At the crossroads of cell signalling and inflammatory disease

Inflammation occurs as a result of exposure of tissues and organs to harmful stimuli such as microbial pathogens, irritants, or toxic cellular components. The primary physical manifestations of inflammation are redness, swelling, heat, pain, and loss of function to the affected area. These processes involve the major cells of the immune system, including monocytes, macrophages, neutrophils, basophils, dendritic cells, mast cells, T-cells, and B-cells. However, examination of a range of inflammatory lesions demonstrates the presence of specific leukocytes in any given lesion. That is, the inflammatory process is regulated in such a way as to ensure that the appropriate leukocytes are recruited. These events are in turn controlled by a host of extracellular molecular regulators, including members of the cytokine and chemokine families that mediate both immune cell recruitment and complex intracellular signalling control mechanisms that characterise inflammation. This review will focus on the role of the main cytokines, chemokines, and their receptors in the pathophysiology of auto-inflammatory disorders, pro-inflammatory disorders, and neurological disorders involving inflammation.

Regulatory T cells and their roles in immune dysregulation and allergy

The main function of the immune system is to fight off potential infections, but also to maintain its activity below a level that would trigger self-reactivity. Regulatory T cells (Tregs) such as forkhead box P3(+) (FOXP3) Tregs and type 1 regulatory T cells (Tr1) play an essential role in this active process, using several distinct suppressive mechanisms. A wide range of pathologies have been associated with altered Treg cell function. This is best exemplified by the impact of mutations of genes essential for Treg function and the associated autoimmune syndromes. This review summarizes the main features of different subtypes of Tregs and focuses on the clinical implications of their altered function in human studies. More specifically, we discuss abnormalities affecting FOXP3(+) Tregs and Tr1 cells that will lead to autoimmune manifestations and/or allergic reactions, and the potential therapeutic use of Tregs.

Chemokines in chronic liver allograft dysfunction pathogenesis and potential therapeutic targets

Despite advances in immunosuppressive drugs, long-term success of liver transplantation is still limited by the development of chronic liver allograft dysfunction. Although the exact pathogenesis of chronic liver allograft dysfunction remains to be established, there is strong evidence that chemokines are involved in organ damage induced by inflammatory and immune responses after liver surgery. Chemokines are a group of low-molecular-weight molecules whose function includes angiogenesis, haematopoiesis, mitogenesis, organ fibrogenesis, tumour growth and metastasis, and participating in the development of the immune system and in inflammatory and immune responses. The purpose of this review is to collect all the research that has been done so far concerning chemokines and the pathogenesis of chronic liver allograft dysfunction and helpfully, to pave the way for designing therapeutic strategies and pharmaceutical agents to ameliorate chronic allograft dysfunction after liver transplantation.

Frequency and activation of CD4+CD25 FoxP3+ regulatory T cells in peripheral blood from children with atopic allergy

BACKGROUND

Atopic allergy is among the immune tolerance-related disorders resulting from a failure of the regulatory network. Regulatory T cells (Tregs) play a leading role in the development of homeostasis in the immune system. The aim of this study was to determine the role of Tregs in the pathogenesis of atopic diseases in children by exploring the relationship between Treg frequency, activation markers and the clinical manifestations of the disease.

METHODS

Twenty allergic and 50 healthy children were enrolled to the study. Peripheral blood mononuclear cells were stained with monoclonal antibodies (anti-CD25-CD4-CD127-FoxP3-CD69-CD71) and evaluated using flow cytometry. Tregs were identified as CD4+CD25(+/high)FoxP3+CD127- T cells.

RESULTS

The percentage of Tregs in allergic patients (2.3%) was significantly decreased in comparison to healthy controls (4.6%, p = 0.003). The frequency of Tregs in patients with symptoms of atopic dermatitis and/or food allergy (1.7%) was significantly lower than in patients without these symptoms (2.9%, p = 0.04). A significant correlation between the percentage of Tregs and the sIgE serum concentration was observed (p = 0.037). Relative fluorescence intensities of FoxP3 expression in allergic patients were higher than in healthy controls (p = 0.00004). The frequency of CD4+CD25(high)CD127-CD71+ cells did not differ between the groups.

CONCLUSIONS

Tregs display substantial deficiencies in atopic children, especially in children with multiorgan involvement, compared to patients with single organ manifestations. Additionally, there is an association between Tregs and the sIgE serum concentration. Better identification and characterization of Tregs in allergy is needed as they limit responses to foreign antigens, thereby minimizing T cell-mediated immunopathology in allergic diseases.

Epigenetically mediated pathogenic effects of phenanthrene on regulatory T cells

Phenanthrene (Phe), a polycyclic aromatic hydrocarbon (PAH), is a major constituent of urban air pollution. There have been conflicting results regarding the role of other AhR ligands 2,3,7,8- tetrachlorodibenzo-p-dioxin (TCDD) and 6-formylindolo [3,2-b]carbazole (FICZ) in modifying regulatory T cell populations (Treg) or T helper (Th)17 differentiation, and the effects of Phe have been understudied. We hypothesized that different chemical entities of PAH induce Treg to become either Th2 or Th17 effector T cells through epigenetic modification of FOXP3. To determine specific effects on T cell populations by phenanthrene, primary human Treg were treated with Phe, TCDD, or FICZ and assessed for function, gene expression, and phenotype. Methylation of CpG sites within the FOXP3 locus reduced FOXP3 expression, leading to impaired Treg function and conversion of Treg into a CD4⁺CD25^lo Th2 phenotype in Phe-treated cells. Conversely, TCDD treatment led to epigenetic modification of IL-17A and conversion of Treg to Th17 T cells. These findings present a mechanism by which exposure to AhR-ligands mediates human T cell responses and begins to elucidate the relationship between environmental exposures, immune modulation, and initiation of human disease.

Asthma discordance in twins is linked to epigenetic modifications of T cells

T cells mediate the inflammatory responses observed in asthma among genetically susceptible individuals and have been suspected to be prone to epigenetic regulation. However, these relationships are not well established from past clinical studies that have had limited capacity to control for the effects of variable genetic predisposition and early environmental exposures. Relying on a cohort of monozygotic twins discordant for asthma we sought to determine if epigenetic modifications in T cells were associated with current asthma and explored whether such modifications were associated with second hand smoke exposures. Our study was conducted in a monozygotic twin cohort of adult twin pairs (n = 21) all discordant for asthma. Regulatory T cell (Treg) and effector T cell (Teff) subsets were assessed for levels of cellular function, protein expression, gene expression and CpG methylation within Forkhead box P3 (FOXP3) and interferon gamma-γ (IFNγ) loci. Comparisons by asthma and current report of exposure to second hand smoke were made. Treg from asthmatic discordant twins demonstrated decreased FOXP3 protein expression and impaired Treg function that was associated with increased levels of CpG methylation within the FOXP3 locus when compared to their non-asthmatic twin partner. In parallel, Teff from discordant asthmatic twins demonstrated increased methylation of the IFNγ locus, decreased IFNγ expression and reduced Teff function when compared to Teff from the non-asthmatic twin. Finally, report of current exposure to second hand smoke was associated with modifications in both Treg and Teff at the transcriptional level among asthmatics. The results of the current study provide evidence for differential function of T cell subsets in monozygotic twins discordant for asthma that are regulated by changes in DNA methylation. Our preliminary data suggest exposure to second hand smoke may augment the modified T cell responses associated with asthma.

Combination of a TLR4 ligand and anaphylatoxin C5a for the induction of antigen-specific cytotoxic T cell responses

The complement system and Toll-like receptors (TLR) are key innate defense systems which might interact synergistically on dendritic cells (DC) to reinforce adaptive immunity. In a previous work, we found that the extra domain A from fibronectin EDA (an endogenous ligand for TLR4) can favour antigen delivery to DC and induce their maturation. Given the potential of anaphylatoxins to cause inflammation and activation of myeloid cells, we hypothesized that a fusion protein between EDA, and anaphylatoxins C3a, C4a or C5a together with an antigen might improve the immunogenicity of the antigen. Naked DNA immunization with a construct expressing the fusion protein between C5a, EDA and the cytotoxic T cell epitope SIINFEKL from ovalbumin, induced strong antigen specific T cell responses. The purified recombinant fusion protein EDA-SIINFEKL-C5a induced activation of dendritic cells, the production of proinflammatory cytokines/chemokines and stimulated antigen presenting cell migration and NK cell activation. As compared to EDA-SIINFEKL, the fusion protein EDA-SIINFEKL-C5a did not induce the production of the immunosuppressive molecules IL-10, CCL17, CCL1, CXCL12 or XCL1 by DC. Moreover, EDA-SIINFEKL-C5a induced strong specific T cell responses in vivo and protected mice against E.G7-OVA tumor growth more efficiently than EDA-SIINFEKL or SIINFEKL-C5a recombinant proteins. Our results suggest that fusion proteins containing EDA, the anaphylatoxin C5a and the antigen may serve as a suitable strategy for the development of anti-tumor or anti-viral vaccines.

Targeting chemokine receptors in chronic inflammatory diseases: an extensive review

The traffic of the different types of immune cells is an important aspect in the immune response. Chemokines are soluble peptides that are able to attract cells by interaction with chemokine receptors on their target cells. Several different chemokines and receptors exist enabling the specific trafficking of different immune cells. In chronic inflammatory disorders there is abundance of immune cells present at the inflammatory site. This review focuses on the role of chemokine receptors in chronic inflammatory disorders of the lungs, intestine, joints, skin and nervous system and the potential of targeting these receptors as therapeutic intervention in these disorders.

Antigen-specific TGF-β-induced regulatory T cells secrete chemokines, regulate T cell trafficking, and suppress ongoing autoimmunity

The ability to regulate ongoing inflammation using regulatory T cells (Tregs) is under intense investigation. Strategies to induce and expand Ag-specific Tregs are being developed, and whether various types of Tregs are suppressive in the inflammatory conditions associated with ongoing disease needs to be determined. In this study, we report that TGF-β-induced Tregs (iTregs) and expanded Tregs specific for a major self-Ag in autoimmune gastritis suppress inflammation and associated pathology when administered late in the process of ongoing disease. Transferred iTregs localized to the stomach, maintained Foxp3 and suppressor functions, and engaged several distinct mechanisms to alleviate disease progression. In addition to suppressing the production of inflammatory cytokines in the stomach and preventing the destruction of parietal cells, we show that iTregs secrete numerous chemokines and regulate both iTreg and effector T cell trafficking into the stomach. These data support efforts to use iTregs in therapies to treat autoimmunity and inflammatory diseases and provide novel insight into the biological mechanisms of iTreg-mediated immune suppression.

Expansion of CD4+CD25+ helper T cells without regulatory function in smoking and COPD

BACKGROUND

Regulatory T cells have been implicated in the pathogenesis of COPD by the increased expression of CD25 on helper T cells along with enhanced intracellular expression of FoxP3 and low/absent CD127 expression on the cell surface.

METHOD

Regulatory T cells were investigated in BALF from nine COPD subjects and compared to fourteen smokers with normal lung function and nine never-smokers.

RESULTS

In smokers with normal lung function, the expression of CD25+CD4+ was increased, whereas the proportions of FoxP3+ and CD127+ were unchanged compared to never-smokers. Among CD4+ cells expressing high levels of CD25, the proportion of FoxP3+ cells was decreased and the percentage of CD127+ was increased in smokers with normal lung function. CD4+CD25+ cells with low/absent CD127 expression were increased in smokers with normal lung function, but not in COPD, when compared to never smokers.

CONCLUSION

The reduction of FoxP3 expression in BALF from smokers with normal lung function indicates that the increase in CD25 expression is not associated with the expansion of regulatory T cells. Instead, the high CD127 and low FoxP3 expressions implicate a predominantly non-regulatory CD25+ helper T-cell population in smokers and stable COPD. Therefore, we suggest a smoking-induced expansion of predominantly activated airway helper T cells that seem to persist after COPD development.

Tumor infiltrating regulatory T cells: tractable targets for immunotherapy

Several studies have linked tumor-infiltration by regulatory T cells with poor patient outcome. Targeting the mechanisms by which regulatory T cells traffic to and persist in the tumor may circumvent tumor immune-escape by de-restricting T cell-mediated cytotoxicity. In this review, we describe the principle axes that govern regulatory T cell migration and the mechanisms that underpin their immunosuppressive activity in cancer. Inhibiting either the migration or function of regulatory T cells may enhance host-anti-cancer immune responses and as such are attractive and tractable targets for therapeutic intervention.

What's new in asthma pathophysiology and immunopathology?

Research on asthma pathophysiology over the past decade has expanded the complex repertoire involved in the pathophysiology of asthma to include inflammatory, immune and structural cells, as well as a wide range of mediators. Studies have identified a role for connective and other mesenchymal tissues involved in airway remodeling. Recent findings have implicated the innate immune response in asthma and have revealed interesting patterns of interaction between the innate and adaptive immune response and the associated complex chronic inflammatory reaction. New immune cell populations have also been added to this repertoire, including Tregs, natural killer T cells and Th17 cells. The role of the eosinophil, a prominent pathological feature in most asthma phenotypes, has also been expanding to include roles such as tissue modifiers and immune regulators via a number of fascinating and hitherto unexplored mechanistic pathways. In addition, new and significant roles have been proposed for airway smooth muscle cells, fibroblasts, epithelial and endothelial cells. Tissue remodeling is now considered an integral element of asthma pathophysiology. Finally, an intricate network of mediators, released from both immune and inflammatory cells, including thymus stromal lymphopoietin and matrix metalloproteinases, have added to the complex milieu of asthma immunity and inflammation. These findings have implications for therapy and the search for novel strategies towards better disease management. Sadly, and perhaps due to the complex nature of asthma, advances in therapeutic discoveries and developments have been limited. Thus, understanding the precise roles played by the numerous dramatis personae in this odyssey, both individually and collectively within the context of asthma pathophysiology, continues to pose new challenges. It is clear that the next stage in this saga is to embark on studies that transcend reductionist approaches to involve system analysis of the complex and multiple variables involved in asthma, including the need to narrow down the phenotypes of this condition based on careful analysis of the organs (lung and airways), cells, mediators and other factors involved in bronchial asthma.

Human CD4+ FOXP3+ regulatory T cells produce CXCL8 and recruit neutrophils

One of the defining features of the majority of FOXP3(+) Tregs is their inability to produce typical T-cell-derived cytokines. Little is known, however, about their capacity to produce chemokines. As Tregs are constitutively present in, and rapidly traffic to, non-lymphoid tissues, we hypothesized that they may produce chemokines to direct the composition of cells that infiltrate inflamed tissues. Surprisingly, we found that Tregs produce high amounts of CXCL8 (IL-8), a potent neutrophil chemoattractant. Tregs also produced other CC and CXC family chemokines, including CCL2-5, CCL7, and CXCL10. Whereas ectopic expression of FOXP3 suppressed cytokine production, it significantly induced CXCL8. Moreover, supernatants from Tregs attracted neutrophils via a CXCL8-dependent mechanism. These data provide the first evidence that although classical Tregs are defined by their lack of proinflammatory cytokine production, they secrete significant quantities of chemokines and thus may have an unappreciated role in directing the recruitment of immune cells.

Ambient air pollution impairs regulatory T-cell function in asthma

BACKGROUND

Asthma is the most frequent chronic disease in children, and children are at high risk for adverse health consequences associated with ambient air pollution (AAP) exposure. Regulatory T (Treg) cells are suppressors of immune responses involved in asthma pathogenesis. Treg-cell impairment is associated with increased DNA methylation of Forkhead box transcription factor 3 (Foxp3), a key transcription factor in Treg-cell activity. Because AAP exposure can induce epigenetic changes, we hypothesized that Treg-cell function would be impaired by AAP, allowing amplification of an inflammatory response.

OBJECTIVES

To assess whether exposure to AAP led to hypermethylation of the Foxp3 gene, causing impaired Treg-cell suppression and worsened asthma symptom scores.

METHODS

Children with and without asthma from Fresno, Calif (high pollution, Fresno Asthma Group [FA], n = 71, and Fresno Non Asthmatic Group, n = 30, respectively), and from Stanford, Calif (low pollution, Stanford Asthma Group, n = 40, and Stanford Non Asthmatic Group, n = 40), were enrolled in a cross-sectional study. Peripheral blood Treg cells were used in functional and epigenetic studies. Asthma outcomes were assessed by Global Initiative in Asthma score.

RESULTS

Fresno Asthma Group Treg-cell suppression was impaired and FA Treg-cell chemotaxis were reduced compared with other groups (P ≤ .05). Treg-cell dysfunction was associated with more pronounced decreases in asthma Global Initiative in Asthma score in FA versus the Stanford Asthma Group. Foxp3 was decreased in FA compared with the Fresno Non Asthmatic Group (P ≤ .05). FA also contained significantly higher levels of methylation at the Foxp3 locus (P ≤ .05).

CONCLUSION

Increased exposure to AAP is associated with hypermethylation of the Foxp3 locus, impairing Treg-cell function and increasing asthma morbidity. AAP could play a role in mediating epigenetic changes in Treg cells, which may worsen asthma by an immune mechanism.

The other T helper cells in asthma pathogenesis

The complex phenotype of allergic bronchial asthma involves a variable degree of bronchoobstruction, increased mucus production, and airway remodeling. So far it is suggested that it arises from multiple interactions of infiltrating and structural cells in the context of chronic airway inflammation that is orchestrated by T helper 2 (TH2) cells. By secreting a plethora of typical mediators such as interleukin (IL) 4, IL-5, and IL-13, these cells hold a key position in asthma pathogenesis. However, therapeutic approaches targeting these TH2-type mediators failed to improve asthma symptoms and impressively showed that asthma pathogenesis cannot be reduced by TH2 cell functions. Recently, other T helper cells, that is, TH9 and TH17 cells, have been identified and these cells also contribute to asthma pathogenesis, the processes leading to formation or aggravation of asthma. Furthermore, TH25 cells, TH3 cells, and regulatory T cells have also been implicated in asthma pathogenesis. This paper aims at summarizing recent insights about these new T helper cells in asthma pathogenesis.

Migration of regulatory T cells toward airway epithelial cells is impaired in chronic rhinosinusitis with nasal polyposis

The pathogenesis of chronic rhinosinusitis with nasal polyposis (CRSwNP) is still unclear. To evaluate the role of regulatory T cells (Treg) in the pathogenesis of nasal polyposis, we tested migration potential of Treg purified from subjects with CRSwNP, CRS without NP and controls. The nasal tissue expressions of FOXP3 were analyzed by means of RT-PCR and double immunohistochemistry. Chemotaxis assays were used to evaluate the migration potential of Treg onto bronchial epithelial cells and primary nasal epithelial cells, and toward chemokines. FOXP3(+)CD3(+) cells frequency and FOXP3 transcript expression in nasal tissue, and migration potentials of Treg toward airway epithelial cells and CCL1 were significantly lower in CRSwNP compared with other groups (P<0.05). These results indicate that migration potential of Treg is decreased in CRSwNP subjects, and this may be one of the reasons why tissue infiltration of Treg was decreased as seen in the immunohistochemistry of nasal polyps from CRSwNP subjects.

Epoprostenol-associated pneumonitis: diagnostic use of a T-cell proliferation assay

We describe a case of severe drug-induced interstitial pneumonitis in a woman with idiopathic pulmonary arterial hypertension receiving epoprostenol confirmed by a drug T-cell proliferation assay. Proliferation assays were completed in our patient and in a healthy control. Isolated T cells were incubated with CD3-depleted peripheral blood mononuclear cells and then stimulated to proliferate with (3)H-thymidine in the presence of epoprostenol, other prostanoid analogs, and controls. A significant (p < 0.001) T-cell proliferation response occurred in our patient in the presence of epoprostenol alone. There was a trend towards an increased T-cell response to treprostinil but this was statistically insignificant. There was no significant T-cell response to the diluent alone, normal saline, iloprost, or alprostadil. There was no significant proliferation to any drug in the healthy control. Hence, a drug T-cell proliferation assay confirmed that epoprostenol can rarely incite a profound inflammatory response in the pulmonary interstitium.

Immunomodulatory nanoparticles as adjuvants and allergen-delivery system to human dendritic cells: Implications for specific immunotherapy

Novel adjuvants and antigen-delivery systems with immunomodulatory properties that shift the allergenic Th2 response towards a Th1 or regulatory T cell response are desired for allergen-specific immunotherapy. This study demonstrates that 200-nm sized biodegradable poly(gamma-glutamic acid) (gamma-PGA) nanoparticles (NPs) are activators of human monocyte-derived dendritic cells (MoDCs). Gamma-PGA NPs are efficiently internalized by immature MoDCs and strongly stimulate production of chemokines and inflammatory cytokines as well as up-regulation of co-stimulatory molecules and immunomodulatory mediators involved in efficient T cell priming. Furthermore, MoDCs from allergic subjects stimulated in vitro with a mixture of gamma-PGA NPs and extract of grass pollen allergen Phleum pratense (Phl p) augment allergen-specific IL-10 production and proliferation of autologous CD4(+) memory T cells. Thus, gamma-PGA NPs are promising as sophisticated adjuvants and allergen-delivery systems in allergen-specific immunotherapy.

Genes regulated by Nkx2-3 in siRNA-mediated knockdown B cells: implication of endothelin-1 in inflammatory bowel disease

Nkx2-3 gene variants are strongly associated with inflammatory bowel disease (IBD) and its expression is up-regulated in Crohn's disease (CD). However, the nature of its role underlying IBD pathogenesis is unknown. We investigated the genes regulated by Nkx2-3 using cDNA microarray. A small interfering RNA (siRNA)-mediated knockdown of Nkx2-3 in a B cell line from a CD patient was generated. Gene expression was profiled on high-density cDNA microarrays representing over 25,000 genes. Ingenuity pathway analysis (IPA) was used to identify gene networks according to biological functions and associated pathways. Expression profiling analysis by cDNA microarray showed that 125 genes were regulated by Nkx2-3 knockdown (fold change >or=3.0, p<0.01), among which 51 genes were immune and inflammatory response genes. Microarray results were validated by RT-PCR and further confirmed in a B cell line expressing siRNA of Nkx2-3 from an additional CD patient. The results showed that Nkx2-3 was up-regulated (p<0.05) and EDN1 was down-regulated (p<0.05) in B cell lines from CD patients. mRNA expression levels of Nkx2-3 were negatively correlated with those of EDN1 (r=-0.6044, p<0.05). EDN1 was also down-regulated in intestinal tissues from UC patients (p<0.05). Our present results demonstrate that a decrease in Nkx2-3 gene expression level can profoundly alter the expression of genes and cellular functions relevant to the pathogenesis and progression of IBD, such as EDN1.

The pathogenesis of acute pulmonary viral and bacterial infections: investigations in animal models

Acute viral and bacterial infections in the lower respiratory tract are major causes of morbidity and mortality worldwide. The proper study of pulmonary infections requires interdisciplinary collaboration among physicians and biomedical scientists to develop rational hypotheses based on clinical studies and to test these hypotheses in relevant animal models. Animal models for common lung infections are essential to understand pathogenic mechanisms and to clarify general mechanisms for host protection in pulmonary infections, as well as to develop vaccines and therapeutics. Animal models for uncommon pulmonary infections, such as those that can be caused by category A biothreat agents, are also very important because the infrequency of these infections in humans limits in-depth clinical studies. This review summarizes our understanding of innate and adaptive immune mechanisms in the lower respiratory tract and discusses how animal models for selected pulmonary pathogens can contribute to our understanding of the pathogenesis of lung infections and to the search for new vaccines and therapies.

Pathogenic mechanisms of allergic inflammation: atopic asthma as a paradigm

Prospective studies tracking birth cohorts over periods of years indicate that the seeds for atopic asthma in adulthood are sewn during early life. The key events involve programming of functional phenotypes within the immune and respiratory systems which determine long-term responsiveness to ubiquitous environmental stimuli, particularly respiratory viruses and aeroallergens. A crucial component of asthma pathogenesis is early sensitization to aeroallergens stemming from a failure of mucosal tolerance mechanisms during the preschool years, which is associated with delayed postnatal maturation of a range of adaptive and innate immune functions. These maturational defects also increase risk for severe respiratory infections, and the combination of sensitization and infections maximizes risk for early development of the persistent asthma phenotype. Interactions between immunoinflammatory pathways stimulated by these agents also sustain the disease in later life as major triggers of asthma exacerbations. Recent studies on the nature of these interactions suggest the operation of an infection-associated lung:bone marrow axis involving upregulation of FcERlalpha on myeloid precursor populations prior to their migration to the airways, thus amplifying local inflammation via IgE-mediated recruitment of bystander atopic effector mechanisms. The key participants in the disease process are airway mucosal dendritic cells and adjacent epithelial cells, and transiting CD4(+) effector and regulatory T-cell populations, and increasingly detailed characterization of their roles at different stages of pathogenesis is opening up novel possibilities for therapeutic control of asthma. Of particular interest is the application of genomics-based approaches to drug target identification in cell populations of interest, exemplified by recent findings discussed below relating to the gene network(s) triggered by activation of Th2-memory cells from atopics.

Immunologic messenger molecules: cytokines, interferons, and chemokines

Cytokines and chemokines are secreted proteins involved in numerous aspects of cell growth, differentiation, and activation. A prominent feature of these molecules is their effect on the immune system with regard to cell trafficking and development of immune tissue and organs. The nature of an immune response determines which cytokines are produced and ultimately whether the response is cytotoxic, humoral, cell mediated, or allergic. For this chapter, cytokines are grouped according to those that are predominantly antigen-presenting cell or T lymphocyte derived; that mediate cytotoxic, humoral, cell mediated, and allergic immunity; or that are immunosuppressive. A discussion of chemokine function and their role in cell trafficking and disease follows.

Impaired IL-10-dependent induction of tolerogenic dendritic cells by CD4+CD25hiCD127lo/- natural regulatory T cells in human allergic asthma

RATIONALE

Tolerogenic dendritic cells and natural regulatory T cells have been implicated in the process of infectious tolerance in human allergic asthma. However, the significance of the influence of natural regulatory T cells on tolerogenic dendritic cells in the disease has not been investigated.

OBJECTIVES

We aimed to characterize the mechanism of induction of the tolerogenic phenotype in circulating blood dendritic cells by allergic asthmatic natural regulatory T cells.

METHODS

The study was performed in a cohort of 21 subjects with allergic asthma, 21 healthy control subjects, and 21 subjects with nonallergic asthma. We cultured blood dendritic cells with natural regulatory T cells to study the induction of tolerogenic dendritic cells. Flow cytometry and proliferation assays were employed to analyze phenotype and function of dendritic cells as well as IL-10 production from natural regulatory T cells.

MEASUREMENTS AND MAIN RESULTS

Dendritic cells cultured with natural regulatory T cells up-regulated IL-10, down-regulated costimulatory molecules, and stimulated the proliferation of CD4(+)CD25(-) effector T cells less potently. Allergic asthmatic natural regulatory T cells were significantly less efficient in inducing this tolerogenic phenotype of dendritic cells compared with healthy control and nonallergic asthmatic counterparts. Furthermore, this defective function of natural regulatory T cells was associated with their decreased IL-10 expression, disease severity, and could be reversed by oral corticosteroid therapy.

CONCLUSIONS

These results provided the first evidences of impaired induction of tolerogenic dendritic cells mediated by natural regulatory T cells in human allergic asthma.

Regulatory T cells and asthma

Airway inflammation in asthma is characterized by activation of T helper type-2 (Th2) T cells, IgE production and eosinophilia. In many cases, this process is related to an inappropriate T cell response to environmental allergens, and other T cell-dependent pathways may also be involved (such as Th17). Regulatory T cells (Tregs) are T cells that suppress potentially harmful immune responses. Two major subsets of Treg are CD25(hi), Foxp3(+)Tregs and IL-10-producing Tregs. There is evidence that the numbers or function of both subsets may be deficient in patients with atopic allergic disease. Recent work has extended these findings into the airway in asthma where Foxp3 expression was reduced and CD25(hi) Treg-suppressive function was deficient. In animal models of allergic airways disease, Tregs can suppress established airway inflammation and airway hyperresponsiveness, and protocols to enhance the development, recruitment and function of Tregs have been described. Together with studies of patients and in vitro studies of human T cells, these investigations are defining potential interventions to enhance Treg function in the airway in asthma. Existing therapies including corticosteroids and allergen immunotherapy act on Tregs, in part to increase IL-10 production, while vitamin D3 and long-acting beta-agonists enhance IL-10 Treg function. Other possibilities may be enhancement of Treg function via histamine or prostanoid receptors, or by blocking pro-inflammatory pathways that prevent suppression by Tregs (activation of Toll-like receptors, or production of cytokines such as IL-6 and TNF-alpha). As Tregs can also suppress the potentially beneficial immune response important for controlling infections and cancer, a therapeutic intervention should target allergen- or site-specific regulation.

Regulatory T cell dysfunction in subjects with common variable immunodeficiency complicated by autoimmune disease

Approximately 25% of subjects with common variable immunodeficiency (CVID) develop autoimmune disease. We analyzed T cell subsets, specifically regulatory T cells along with B cell subsets to determine whether there were changes in regulatory T cells which would correlate with the autoimmune disease clinical phenotype in CVID subjects. We hypothesized that regulatory T cell (CD4+CD25hiCD127lo) suppressive function would be impaired in CVID subjects with autoimmune disease. Using purified, sorted Treg from CVID subjects (n=14) and from healthy controls (HC, n=5) in standard suppression assays, we found the suppressive function of Treg from CVID subjects with autoimmune disease (CVID w/ AI, n=8) to be significantly attenuated compared to CVID subjects with no autoimmune disease (CVID w/o AI, n=6) and to HC (n=5). A number of proteins associated with Treg function were decreased in expression as detected through immunofluorescent antibody via flow cytometry (mean fluorescence intensity (MFI) of FoxP3, Granzyme A, XCL1, pSTAT5, and GITR in Treg was significantly lower (by up to 3 fold) in CVID w/ AI compared to CVID w/o AI and HC. Furthermore, a statistically significant correlation was found between intracellular MFI of FoxP3, Granzyme A, and pSTAT5 in Treg and the degree of Treg dysfunction. These results suggest that attenuation of Treg function is associated with autoimmune disease in CVID subjects and may contribute to autoimmune pathogenesis.