Excessive CD4+ T cells co-expressing interleukin-17 and interferon-γ in patients with Behçet's disease

Genome-wide association analysis reveals the associations of NPHP4, TYW1-AUTS2 and SEMA6D for Behçet's disease and HLA-B*46:01 for its intestinal involvement

BACKGROUND

Intestinal involvement in Behçet's disease (BD) is associated with poor prognosis and is more prevalent in East Asian than in Mediterranean populations. Identifying the genetic causes of intestinal BD is important for understanding the pathogenesis and for appropriate treatment of BD patients.

METHODS

We performed genome-wide association studies (GWAS) and imputation/replication genotyping of human leukocyte antigen (HLA) alleles for 1,689 Korean and Turkish patients with BD (including 379 patients with intestinal BD) and 2,327 healthy controls, followed by replication using 593 Japanese patients with BD (101 patients with intestinal BD) and 737 healthy controls. Stratified cross-phenotype analyses were performed for 1) overall BD, 2) intestinal BD, and 3) intestinal BD without association of overall BD.

RESULTS

We identified three novel genome-wide significant susceptibility loci including NPHP4 (rs74566205; P=1.36 × 10-8), TYW1-AUTS2 (rs60021986; P=1.14 × 10-9), and SEMA6D (rs4143322; P=5.54 × 10-9) for overall BD, and a new association with HLA-B*46:01 for intestinal BD (P=1.67 × 10-8) but not for BD without intestinal involvement. HLA peptide binding analysis revealed that Mycobacterial peptides, have a stronger binding affinity to HLA-B*46:01 compared to the known risk allele HLA-B*51:01.

CONCLUSIONS

HLA-B*46:01 is associated with the development of intestinal BD; NPHP4, TYW1-AUTS2, and SEMA6D are susceptibility loci for overall BD.

Deficiency of peripheral CLA+ Tregs and clinical relevance in Behcet's syndrome

BACKGROUND

Autoimmune responses have been suggested to involvement in patients with Behcet's syndrome (BS). There has been growing attention towards the roles of cutaneous lymphocyte antigen (CLA)+ regular T cells (Tregs) in autoimmune diseases. The role of CLA+ Tregs in BS is still uncertain. This study aims to clarify the impact of CLA+ Tregs on BS.

METHODS

We collected peripheral blood from a total of 107 patients with BS and 114 healthy controls (HCs). The number of CLA+ Tregs, natural killer (NK) cells, B cells, and several subtypes of CD4+ T cells were detected using flow cytometry and compared between patients and HCs.

RESULTS

The absolute number and proportion of CLA+ Tregs among CD4+ T lymphocytes and CD4+ Tregs were lower in patients with BS than in HCs. CLA+ Tregs were positively related with NK cells (r = 0.500, P < 0.001) and B cells (r = 0.470, P < 0.001) and negatively related with effector T cells (r=-0.402, P < 0.001) in patients with BS. Patients with BS and arterial aneurysms had CLA+ Treg cell deficiency. A decreased proportion of CLA+ Tregs was associated with arterial aneurysms in patients with BS. The proportion of CLA+ Tregs in patients with BS increased with corticosteroids and immunosuppressants.

CONCLUSION

CLA+ Tregs decrease in association with arterial aneurysm in patients with BS. CLA+ Tregs may be a predictor of response to BS treatment.

The role of miRNAs in Behçet's disease

The symptoms of Behçet's disease (BD), a multisystemic condition with autoimmune and inflammation as hallmarks, include arthritis, recurring oral and vaginal ulcers, skin rashes and lesions, and involvement of the nervous, gastrointestinal, and vascular systems. Non-coding RNAs (ncRNAs), including microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs), may be important regulators of inflammation and autoimmune disease. These ncRNAs are essential to the physiological and pathophysiological disease course, and miRNA in particular has received significant attention for its role and function in BD and its potential use as a diagnostic biomarker in recent years. Although promising as therapeutic targets, miRNAs must be studied further to fully comprehend how miRNAs in BD act biologically.

Distinct Th17 effector cytokines differentially promote microglial and blood-brain barrier inflammatory responses during post-infectious encephalitis

Group A Streptococcus (GAS) infections can cause neuropsychiatric sequelae in children due to post-infectious encephalitis. Multiple GAS infections induce migration of Th17 lymphocytes from the nose into the brain, which are critical for microglial activation, blood-brain barrier (BBB) and neural circuit impairment in a mouse disease model. How endothelial cells (ECs) and microglia respond to GAS infections, and which Th17-derived cytokines are essential for these responses are unknown. Using single-cell RNA sequencing and spatial transcriptomics, we found that ECs downregulate BBB genes and microglia upregulate interferon-response, chemokine and antigen-presentation genes after GAS infections. Several microglial-derived chemokines were elevated in patient sera. Administration of a neutralizing antibody against interleukin-17A (IL-17A), but not ablation of granulocyte-macrophage colony-stimulating factor (GM-CSF) in T cells, partially rescued BBB dysfunction and microglial expression of chemokine genes. Thus, IL-17A is critical for neuropsychiatric sequelae of GAS infections and may be targeted to treat these disorders.

Atherosclerosis and Inflammation: Insights from the Theory of General Pathological Processes

Recent advances have greatly improved our understanding of the molecular mechanisms behind atherosclerosis pathogenesis. However, there is still a need to systematize this data from a general pathology perspective, particularly with regard to atherogenesis patterns in the context of both canonical and non-classical inflammation types. In this review, we analyze various typical phenomena and outcomes of cellular pro-inflammatory stress in atherosclerosis, as well as the role of endothelial dysfunction in local and systemic manifestations of low-grade inflammation. We also present the features of immune mechanisms in the development of productive inflammation in stable and unstable plaques, along with their similarities and differences compared to canonical inflammation. There are numerous factors that act as inducers of the inflammatory process in atherosclerosis, including vascular endothelium aging, metabolic dysfunctions, autoimmune, and in some cases, infectious damage factors. Life-critical complications of atherosclerosis, such as cardiogenic shock and severe strokes, are associated with the development of acute systemic hyperinflammation. Additionally, critical atherosclerotic ischemia of the lower extremities induces paracoagulation and the development of chronic systemic inflammation. Conversely, sepsis, other critical conditions, and severe systemic chronic diseases contribute to atherogenesis. In summary, atherosclerosis can be characterized as an independent form of inflammation, sharing similarities but also having fundamental differences from low-grade inflammation and various variants of canonical inflammation (classic vasculitis).

Characterization of immune responses associated with ERAP-1 expression in HSV-induced Behçet's disease mouse model

Behçet's disease (BD) is a chronic multisystem inflammatory disorder. Endoplasmic reticulum aminopeptidase 1 (ERAP1) polymorphism has been reported as a risk factor for BD. However, the immunological role of ERAP1 in BD remains unclear. Therefore, the purpose of this study was to investigate the immunological role of ERAP1 in BD using a mouse model. ERAP1 incomplete expressing mice (ERAP1 hetero, +/-) were generated and inoculated with herpes simplex virus 1 to produce a BD mouse model. In these mice, dendritic cell activation markers and other immune response-related markers were analyzed. Among them, the factor showing a significant difference between ERAP+/- BD mice and WT BD mice was IL-17. In ERAP+/-, BD had significantly different expression levels of CD80, CD11b, Ly6G, RORγt, IFNγ, and IL-17 compared to asymptomatic controls. This study demonstrates ERAP1 defective expressions play an important role in BD development through inappropriate regulation of Th17.

Interferon-α2a induces CD4+ T cell apoptosis and suppresses Th1/Th17 responses via upregulating IRF1-mediated PDL1 expression in dendritic cells from Behcet's uveitis

Recombinant interferon-α2a (IFNα2a) has been widely used in the treatment of Behcet's uveitis (BU). However, the mechanism underlying its effects remains poorly understood. In this study, we investigated its effect on dendritic cells (DCs) and CD4⁺ T cells, which are essential for the development of BU. Our results showed that the expression of PDL1 and IRF1 was significantly decreased in DCs from active BU patients, and IFNα2a could significantly upregulate PDL1 expression in an IRF1-dependent manner. IFNα2a-treated DCs induced CD4⁺ T cells apoptosis and inhibited the Th1/Th17 immune response in association with reduced secretion of IFN-γ and IL-17. We also found that IFNα2a promoted Th1 cell differentiation and IL-10 secretion by CD4⁺ T cells. Finally, a comparison of patients before and after IFNα2a therapy revealed that the frequencies of Th1/Th17 cells significantly decreased in association with remission of uveitis after IFNα2a therapy. Collectively, these results show that IFNα2a could exert its effects by modulating the function of DCs and CD4⁺ T cells in BU.

T cells in ocular autoimmune uveitis: Pathways and therapeutic approaches

Autoimmune uveitis is a non-infectious intraocular condition that affects the uveal tract of the eye and threatens vision if not treated properly. Increasing evidence suggests that activated CD4⁺ T cells are associated with progressive and permanent destruction of photoreceptors in ocular autoimmune diseases. As such, the purpose of this review is to offer an overview of the role of CD4⁺ T cells in autoimmune uveitis as well as a justification for the current development and assessment of innovative autoimmune uveitis medications targeting CD4⁺ T cells. With an emphasis on T helper (Th)17, Th1, and Th2 cells, follicular helper CD4⁺ T cells, and regulatory T cells, this review presents a summary of recent research related to the pathways and signaling that encourage CD4⁺ T cells to develop into specialized effector cells. We also describe immunotherapeutic approaches based on CD4⁺ T cell subsets and their potential as therapeutic agents for autoimmune disorders.

Inflammation: A New Look at an Old Problem

Pro-inflammatory stress is inherent in any cells that are subject to damage or threat of damage. It is defined by a number of universal components, including oxidative stress, cellular response to DNA damage, unfolded protein response to mitochondrial and endoplasmic reticulum stress, changes in autophagy, inflammasome formation, non-coding RNA response, formation of an inducible network of signaling pathways, and epigenetic changes. The presence of an inducible receptor and secretory phenotype in many cells is the cause of tissue pro-inflammatory stress. The key phenomenon determining the occurrence of a classical inflammatory focus is the microvascular inflammatory response (exudation, leukocyte migration to the alteration zone). This same reaction at the systemic level leads to the development of life-critical systemic inflammation. From this standpoint, we can characterize the common mechanisms of pathologies that differ in their clinical appearance. The division of inflammation into alternative variants has deep evolutionary roots. Evolutionary aspects of inflammation are also described in the review. The aim of the review is to provide theoretical arguments for the need for an up-to-date theory of the relationship between key human pathological processes based on the integrative role of the molecular mechanisms of cellular and tissue pro-inflammatory stress.

Saliva and Serum Cytokine Profiles During Oral Ulceration in Behçet's Disease

Behçet's disease (BD) is a chronic, multi-systemic disorder of unknown aetiology typified by recurrent oral and genital mucocutaneous lesions, uveitis and vasculitis. Innate and adaptive immune system dysregulation has been implicated in pathogenesis with alterations in serum cytokine profiles. Few studies have investigated salivary cytokines in BD, despite more than 90% of BD patients first presenting with oral ulceration. The aim of this pilot study was twofold; firstly to investigate whether cytokine levels in matched serum and saliva samples show a differential profile in BD (with and without oral ulcers), recurrent aphthous stomatitis (RAS) and healthy controls (HCs), and secondly, to explore if any differential profiles in serum and/or saliva could provide a panel of cytokines with diagnostic and therapeutic potential for BD. Concentrations of 12 cytokines (IL-1β, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12p70, IL-17A, IFN-γ, TNF-α, TNF-β) were measured using the Human Th1/Th2 11-Plex FlowCytomix™ kit with IL-17A, in BD (N=20), RAS (N=6) and HCs (N=10). A differential range of cytokines was detected in serum and saliva with the majority of cytokine levels higher in saliva. The most prevalent salivary cytokines were IL-1β, IL-2, IL-8, IL-10 and TNF-α present in all samples in contrast to serum where the most prevalent cytokine detected was IL-8 (91.9%). The least abundant cytokine was IFN-γ in both saliva (43.2%) and serum (2.7%). After normalizing saliva for protein content, BD patients with oral ulcers (BD-MA) had significantly higher levels of salivary IL-1β (p=0.01), IL-8 (p=0.02), TNF-α (p=0.004) and IL-6 (p=0.01) than HCs. Notably, BD patients without oral ulcers (BD-MQ) also had significantly higher salivary IL-1β, IL-8 and TNF-α (p ≤ 0.05) than HCs. During relapsed (BD-RE) and quiet (BD-Q) systemic episodes, salivary IL-β and TNF-α were also significantly increased with IL-8 significantly higher only in BD-Q (p=0.02). BD oral ulcers signify a potential reactivation of systemic inflammation. Identifying cytokines released during asymptomatic episodes and oral ulceration might lead to targeted drug therapy to prevent recurrent oral ulcers and possible disease relapse. This is the first study to report salivary cytokine levels in BD. The detectable levels suggests cytokine profiling of BD saliva may provide an alternative, less invasive, sensitive procedure for frequent monitoring of disease activity and progression.

Comparison of CD4 Counts with Mycophenolate Mofetil versus Methotrexate from the First-line Antimetabolites as Steroid-sparing Treatment (FAST) Uveitis Trial

PURPOSE

Sub-analysis of the FAST Trial comparing change in CD4 (∆CD4) from baseline through 12 months in uveitis patients treated with mycophenolate mofetil (MMF) and methotrexate (MTX).

METHODS

Patients were randomly allocated to 1.5 g twice daily MMF or 25 mg weekly MTX. Individuals with CD4 counts at baseline, 6 months (or treatment failure prior), and 12 months (or treatment failure between 6 and 12 months) were included. The association between treatment and ∆CD4 (cells/μL) was analyzed using multivariable linear regression.

RESULTS

There was no significant difference in ∆CD4 between MMF and MTX at 6 months (-31.7 cells/μL for MMF compared to MTX; 95% CI: -358.2 to 294.8, P = .85) and 12 months (-78.3 cells/μL for MMF compared to MTX; 95% CI: -468.0 to 311.3; P = .69).

CONCLUSION

There was no significant difference in ∆CD4 between MMF and MTX from baseline to 12 months, suggesting that MMF does not confer additional risk of CD4 lymphopenia in uveitic patients.ClinicalTrials.gov Identifier: NCT01829295.

IL-17A and IFN-γ are Up-regulated in CD4 and γδ T Cells in Active Behcet's Disease Patients

Involvement of γδ T cells is implicated in the pathogenesis of Behçet's disease (BD) as a bridge between innate and adaptive responses. IL-17 and IL-22 have also been shown to participate in the BD pathogenesis in addition to IFN-γ. Mainly CD4⁺ T cells are investigated previously for the production of these inflammatory cytokines. In this study, the role of γδ T cells in cytokine-related mechanisms was evaluated in BD in comparison to CD4⁺ T cells. Surface expression of markers for functional states of both CD4⁺ and γδ T cells were compared in ex vivo samples collected from patients with BD and healthy controls (HC). Sixteen active BD (a-BD), 9 inactive BD (i-BD) patients and 25 HC were investigated. The expression of CD161, CCR6 as markers for IL-17 producing cells were analyzed on γδ and CD4⁺ T cells. IFN-γ, IL-17A, IL-22, as well as CD107a (LAMP1) and CD16 (FcγRIII) were evaluated in both cell subtypes after in vitro stimulation. Only IFN-γ production was increased in γδ T cells of a-BD patients. There was no difference in increase of CD107a or decrease of CD16 surface expression on γδ T cells upon stimulation between the groups. Ex vivo IL-17A and both IL-17A/IFN-γ production and expression of CD161, CCR6 by CD4⁺ T cells were increased in a-BD. Along with CD4⁺ T cells, γδ T cells have complementary roles in cytokine production in BD. Higher IFN-γ production of γδ T cells suggests the role of an environmental triggers in BD pathogenesis, whereas IL-17 related activity is mainly provided by CD4⁺ T cells.

Pathogenesis of Behçet's Syndrome: Genetic, Environmental and Immunological Factors

Behçet's syndrome (BS) is a rare systemic vasculitis, characterized by a wide range of different clinical involvements and unpredictable phases of recurrence and remission. BS can be described as a multifactorial disease with an incompletely known etiopathogenesis; in fact, though presenting some peculiar features, such as its typical geographic distribution and the strong association with the well-known genetic predisposing factor HLA-B*51, the cause behind the onset and progression of the disease remains currently not fully understood. Besides genetic HLA and non-HLA predisposing associations and epigenetic influence, environmental factors also play an important role in the pathogenesis of the disease, and among these, infectious agents (both bacterial and viral) and specific microbiome alterations are considered of particular relevance in BS pathogenesis. BS has been included for decades among autoimmune diseases, in light of evidence showing T- and B-cell aberrant responses. However, because of recurrent mucocutaneous lesions and episodes of inflammation without antigen-specific T-cell or autoantibody responses, BS has also been classified among autoinflammatory disorders. Nevertheless, differently from autoinflammatory diseases, BS mildly responds to therapies targeting IL-1, its onset is not usually in childhood, and has high neutrophilic vasculitic involvement. Finally, given the association with HLA class I alleles, similar to spondyloarthropathies, the concept of BS as a major histocompatibility complex (MHC) I -opathy has been introduced. Understanding the complex etiopathogenesis of BS is essential to identify modifiable risk factors of BS occurrence or exacerbation and to develop targeted therapies. This review summarizes current evidence on the main genetic, environmental and immunological factors contributing to BS development.

Behçet syndrome

Behçet syndrome is a systemic vasculitis with an unknown aetiology affecting the small and large vessels of the venous and arterial systems. The presence of symptom clusters, regional differences in disease expression and similarities with, for example, Crohn's disease suggest that multiple pathological pathways are involved in Behçet syndrome. These disease features also make formulating disease criteria difficult. Genetic studies have identified HLA-B*51 as a genetic risk factor. However, the low prevalence of HLA-B*51 in many patients with bona fide disease, especially in non-endemic regions, suggests that other factors must also be operative in Behçet syndrome. Despite lacking a clear aetiological mechanism and definition, management of manifestations that include major vascular disease, eye disease and central nervous system involvement has improved with the help of new technology. Furthermore, even with our incomplete understanding of disease mechanisms, the prognoses of patients with Behçet syndrome, including those with eye disease, continue to improve. New treatment options and a better understanding of the underlying pathogenesis for various manifestations of this condition are required to further improve the management of the disease, which will improve patient quality of life.

CD4+ T-Cell Plasticity in Non-Infectious Retinal Inflammatory Disease

Non-infectious uveitis (NIU) is a potentially sight-threatening disease. Effector CD4⁺ T cells, especially interferon-γ-(IFNγ) producing Th1 cells and interleukin-17-(IL-17) producing Th17 cells, are the major immunopathogenic cells, as demonstrated by adoptive transfer of disease in a model of experimental autoimmune uveitis (EAU). CD4⁺FoxP3⁺CD25⁺ regulatory T cells (Tregs) were known to suppress function of effector CD4⁺ T cells and contribute to resolution of disease. It has been recently reported that some CD4⁺ T-cell subsets demonstrate shared phenotypes with another CD4⁺ T-cell subset, offering the potential for dual function. For example, Th17/Th1 (co-expressing IFNγ and IL-17) cells and Th17/Treg (co-expressing IL-17 and FoxP3) cells have been identified in NIU and EAU. In this review, we have investigated the evidence as to whether these ‘plastic CD4⁺ T cells’ are functionally active in uveitis. We conclude that Th17/Th1 cells are generated locally, are resistant to the immunosuppressive effects of steroids, and contribute to early development of EAU. Th17/Treg cells produce IL-17, not IL-10, and act similar to Th17 cells. These cells were considered pathogenic in uveitis. Future studies are needed to better clarify their function, and in the future, these cell subsets may in need to be taken into consideration for designing treatment strategies for disease.

Behçet disease: From pathogenesis to novel therapeutic options

Behçet disease (BD) is a complex, multi-systemic inflammatory condition mainly hallmarked by oral and genital ulcers which can also affect the vessels, gastrointestinal tract, central nervous system and even the axial skeleton. Without a clear classification among autoimmune or autoinflammatory conditions, BD has been recently classified as a MHC-I-opathy. BD aetiology is still obscure, but it is thought that certain microorganisms can elicit an aberrant adaptive immune response in the presence of a permissive genetic background. Altered T-cell homeostasis, mostly Th1/Th17 expansion and Treg impairment, could lead to an overactivation of the innate immunity, which underlies tissue damage and thus, signs and symptoms. Immunosuppression and/or immunomodulation are central to the BD management. A complex armamentarium ranging from classical synthetic disease-modifying antirrheumatic drugs to new-era biologic agents or small molecules is available in BD, with different therapeutic outcomes depending on disease manifestations. However, the precise disease mechanisms that underlie BD symptoms are not fully deciphered, which may limit their therapeutic potential and add a significant layer of complexity to the treatment decision-making process. The aim of the present review is to provide an exhaustive overview of the latest breakthroughs in BD pathogenesis and therapeutic options.

Experimental Therapeutic Solutions for Behcet's Disease

Behcet’s disease (BD) is a chronic systemic vasculitis with inflammation attacks that involve multiple organs. In addition to numerous mucocutaneous symptoms, notably recurrent oral and genital ulcers, ocular, articular, vascular, gastrointestinal, cardiac, and neurological system involvement can be observed. Mucocutaneous lesions are the primary symptom of the disease in most patients, and they usually occur before major organ involvement and other symptoms of the disease. Recognizing the disease’s mucocutaneous lesions is very important to diagnose at an early stage, control with appropriate treatment and close follow-up, and prevent major organ involvement. Genome-wide association studies (GWAS) in recent years have confirmed that HLA-B*51 is the most significant genetic predisposing factor. The majority of gene polymorphisms have been detected in molecules that respond to microorganisms and genes encoding cytokines and adhesion molecules. The infectious agent S. sanguinis -commonly found in the oral mucosa of patients with BD- or the differences in the salivary or intestinal microbiome composition can trigger innate immune-mediated inflammation sustained by acquired or adaptive immune responses. In antigen-presenting cells (APCs), epistatic interactions between HLA-B*51 and endoplasmic reticulum aminopeptidase 1 (ERAP1) variants lead to the disruption of T-cell homeostasis, especially the activation of Type1 T-helper and Th17 pathway and suppression of regulatory T-cells. Recent developments to clarify the disease’s etiopathogenesis provided us with a better understanding of the mechanism of action of the relatively old drugs while opening a way for many new treatment methods. Apremilast has become an important option in the treatment of mucocutaneous symptoms with its high efficacy and safety. The disease increases the mortality rate, especially in young male patients. New treatments, especially anti-TNF-α agents, have provided significant progress and decreased the mortality rates with their rapid effect and high efficacy in patients with severe organ involvement and resistance to traditional immunosuppressive and immunomodulatory therapies. The use of IL-1, IL-6, IL-17, IL-12/IL-23 antagonists in different organ involvement has gradually increased, and the quality of life has significantly improved in many patients.

Functionally distinct IFN-γ+ IL-17A+ Th cells in experimental autoimmune uveitis: T-cell heterogeneity, migration, and steroid response

Immunopathogenic roles for both Th1 (CD4⁺ IFN-γ⁺ ) and Th17 (CD4⁺ IL-17A⁺ ) cells have been demonstrated in experimental autoimmune uveitis (EAU). However, the role for Th17/Th1 (CD4⁺ T cells co-expressing IFN-γ and IL-17A) cells in EAU is not yet understood. Using interphotoreceptor retinoid-binding protein peptide-induced EAU in mice, we found increased levels of Th17/Th1 cells in EAU retinae (mean 9.6 ± 4.2%) and draining LNs (mean 8.4 ± 3.9%; p = 0.01) relative to controls. Topical dexamethasone treatment effectively reduced EAU severity and decreased retinal Th1 cells (p = 0.01), but had no impact on retinal Th17/Th1 or Th17 cells compared to saline controls. Using in vitro migration assays with mouse CNS endothelium, we demonstrated that Th17/Th1 cells were significantly increased within the migrated population relative to controls (mean 15.6 ± 9.5% vs. 1.9 ± 1.5%; p = 0.01). Chemokine receptor profiles of Th17/Th1 cells (CXCR3 and CCR6) did not change throughout the transendothelial migration process and were unaffected by dexamethasone treatment. These findings support a role for Th17/Th1 cells in EAU and their resistance to steroid inhibition suggests the importance of targeting both Th17 and Th17/Th1 cells for improving therapy.

Common genetic susceptibility loci link PFAPA syndrome, Behçet's disease, and recurrent aphthous stomatitis

Periodic fever, aphthous stomatitis, pharyngitis, and cervical adenitis (PFAPA) syndrome is the most common periodic fever syndrome in children. The disease appears to cluster in families, but the pathogenesis is unknown. We queried two European-American cohorts and one Turkish cohort (total n = 231) of individuals with PFAPA for common variants previously associated with two other oropharyngeal ulcerative disorders, Behçet's disease and recurrent aphthous stomatitis. In a metaanalysis, we found that a variant upstream of IL12A (rs17753641) is strongly associated with PFAPA (OR 2.13, P = 6 × 10-9). We demonstrated that monocytes from individuals who are heterozygous or homozygous for this risk allele produce significantly higher levels of IL-12p70 upon IFN-γ and LPS stimulation than those from individuals without the risk allele. We also found that variants near STAT4, IL10, and CCR1-CCR3 were significant susceptibility loci for PFAPA, suggesting that the pathogenesis of PFAPA involves abnormal antigen-presenting cell function and T cell activity and polarization, thereby implicating both innate and adaptive immune responses at the oropharyngeal mucosa. Our results illustrate genetic similarities among recurrent aphthous stomatitis, PFAPA, and Behçet's disease, placing these disorders on a common spectrum, with recurrent aphthous stomatitis on the mild end, Behçet's disease on the severe end, and PFAPA intermediate. We propose naming these disorders Behçet's spectrum disorders to highlight their relationship. HLA alleles may be factors that influence phenotypes along this spectrum as we found new class I and II HLA associations for PFAPA distinct from Behçet's disease and recurrent aphthous stomatitis.

Effect of combined colchicine-corticosteroid treatment on neutrophil/lymphocyte ratio: a predictive marker in Behçet disease activity

BACKGROUND AND AIMS

Behçet's disease (BD) is an auto-immune vasculitis, characterized by episodic inflammation of multiple organs. The neutrophil to lymphocyte ratio (NLR) is used as a marker of inflammation in several diseases nowadays. While nitric oxide (NO) seem to be involved in BD pathogenicity. Our study aims to investigate the NLR as an inflammatory marker of BD activity as well as to evaluate the relationship between the NO production and NLR in Algerian BD patients with different clinical manifestations before and under colchicine + corticosteroid treatment.

METHODS

For this purpose, we evaluated the NLR as the ratio of neutrophil count to lymphocyte count in naïve and treated active BD patients with different clinical manifestations and in inactive ones. Furthermore, we assessed NO production by the Griess' method in the same patients. Additionally, we evaluated in vivo interferon-γ (IFN-γ) and interleukin-4 (IL-4) levels using ELISA.

RESULTS AND DISCUSSION

Our results indicate that the NLR and nitrite levels were higher in naïve active BD patients. Interestingly, this high ratio and NO production differed according to the clinical manifestations and was associated with an increased risk of mucocutaneous and vascular involvement. Importantly, in treated BD patients NLR was higher in active patients especially in those with mucocutaneous involvement while increased nitrites levels were regardless of the clinical manifestations studied. Both NLR and NO production decreased in these treated active patients. In addition, IL-4 production differed according to the clinical manifestations studied contrary to the IFN-γ production.

CONCLUSION

Collectively our results suggest that the NLR is a potential marker of BD activity in Algerian patients, predicting the disease severity. Moreover, the positive relationship between the NLR and NO production is related to an increased risk of mucocutaneous lesions and vascular involvement. Thus, the application of these two accessible tools could be benefit for the clinical prognosis and treatment of BD.

Interaction between SDF1 and CXCR4 Promotes Photoreceptor Differentiation via Upregulation of NFκB Pathway Signaling Activity in Pax6 Gene-Transfected Photoreceptor Precursors

BACKGROUND

CCL2 (also known as monocyte chemoattractant protein 1) and CX3CR1 (also known as Fractalkine receptor)-deficient mice have damaged photoreceptors.

OBJECTIVES

We examined the interaction of SDF1 and CXCR4 on the differentiation of retinal progenitors into rhodopsin-positive photoreceptors.

METHODS

Cloned retinal progenitors were obtained by Pax6 gene transfection of mouse iPS cells followed by serial dilution. Clones were selected by expression of nestin, Musashi1, Six3, and Chx10 mRNA. Cell surface protein expression was analyzed by flow cytometry. The levels of mRNA and intracellular protein were examined by real-time PCR and immunochemistry, respectively. Transient transfection experiments of retinal progenitors were conducted using a human rhodopsin promoter luciferase plasmid.

RESULTS

We selected 10 clones that expressed Six3, Chx10, Crx, Rx1, Nrl, CD73, and rhodopsin mRNA, which, except for rhodopsin, are photoreceptor precursor markers. Clones expressed both CD73 and CXCR4 on the cell surface and differentiated into rhodopsin-positive photoreceptors, which was reinforced by the addition of exogenous SDF1. A CXCR4 inhibitor AMD3100 blocked SDF1-mediated differentiation of progenitors into photoreceptors. SDF1 enhanced human rhodopsin promoter transcription activity, possibly via the NFκB pathway. Addition of SDF1 to the cell culture induced nuclear translocation of NFκB on retinal progenitor cell clones. Neonatal and newborn mouse retinas expressed SDF1 and CXCR4. Cells in the outer nuclear layer where photoreceptors are located expressed CXCR4 at P14 and P56. Cells in the inner nuclear layer expressed SDF1.

CONCLUSIONS

These findings suggest that retinal progenitor cell differentiation was at least partly regulated by SDF1 and CXCR4 via upregulation of NFκB activity.

Effect of Interferon alfa-2a Treatment on Adaptive and Innate Immune Systems in Patients With Behçet Disease Uveitis

Purpose

To investigate the effect of interferon alfa-2a on T regulatory (Treg) cells, T helper 17 (Th17) cells, and expression of Toll-like receptors (TLRs) in Behçet disease (BD) patients with uveitis.

Methods

Twenty-seven patients who received interferon alfa-2a for active BD uveitis despite conventional immunomodulatory therapies and healthy controls were enrolled. Peripheral blood Treg and Th17 cell frequencies were determined by flow cytometry as gated cells for CD3+CD4+Foxp3+ and CD3+CD4+IL17A+, respectively. Th17 RAR-related orphan receptor (ROR)γt mRNA expression was verified by real-time PCR (RT-PCR). Treg and Th17 cell cytokines were detected by ELISA in the supernatant of short-term cell cultures. RT-PCR was used to assess expression of TLR-2, TLR-3, TLR-4, TLR-8, and TLR-9 using cDNA prepared from CD4+ T cells and monocytes.

Results

Treg and Th17 cell frequencies and Th17 RORγt expression were significantly elevated, and IL-10 concentration in Treg cell supernatants was significantly lower in BD patients than in controls. Th17 IL-17, IL-6, IL-21, IL-22, IL-23, IFN-γ, and TNF-α concentrations were significantly higher and all TLR expressions were significantly elevated in patients. Interferon alfa-2a led to a significant reversal in Treg and Th17 cell frequencies, Th17 RORγt expression, Treg and Th17 cell cytokine production, and TLR expression by CD4+ T cells and monocytes.

Conclusions

Despite a relative increase in Treg cells, impaired IL-10 production suggests that Treg dysfunction may play a role in induction of BD uveitis. Favorable effects of interferon alfa-2a may be associated with recovery of Treg cell function, suppression of Th17 cells, and reduced expression of TLRs on CD4+ T cells and monocytes.

Behçet's Disease: An Overview of Etiopathogenesis

Behçet's disease (BD) is a systemic inflammatory disease with a chronic, relapsing-remitting course of unknown etiology hallmarked predominantly by mucocutaneous lesions and ocular involvement. BD shares some common features with autoimmune and autoinflammatory diseases and spondyloarthropathies (MHC-I-opathies). It is related to more than one pathogenic pathway triggered by environmental factors such as infectious agents in genetically predisposed subjects. The interplay between genetic background and immune system is linked to the BD presentation. Genetic factors have been investigated extensively, and several recent genome-wide association studies have confirmed HLA-B ^* 51 to be the strongest genetic susceptibility factor. However, new non-HLA susceptibility genes have been identified. Genetic variations in the genes encoding the cytokines could affect their function and be associated with disease susceptibility. Infectious agents such as Streptococcus sanguinis or the differences in salivary or gut microbiome composition can be considered to trigger the innate-derived inflammation, which is, subsequently, sustained by adaptive immune responses. Altered trimming of microbial and/or endogenous peptides by endoplasmic reticulum aminopeptidase 1 (ERAP1), presented by HLA-B ^* 51, may play a key role in BD pathogenesis causing an alteration in T cell balance with downregulation of Tregs and expansion of Th1 and Th17. The activity of neutrophils is increased and there is an intense neutrophil infiltration in the early stage of inflammation in organs affected by the disease. Association with HLA-B ^* 51 and increased IL-17 response seems to have an important role in neutrophil activity. In this paper, we provide an overview of the most recent advances on BD etiopathogenesis.

Relative abundance of Megamonas hypermegale and Butyrivibrio species decreased in the intestine and its possible association with the T cell aberration by metabolite alteration in patients with Behcet's disease (210 characters)

OBJECTIVES

We have previously demonstrated that the phylum Actinobacteria, the family Lactobacillaceae, and the genus Bifidobacterium increased in relative abundance of gut microbiota in patients with Behcet's disease (BD). The phylum Firmicutes and the class Clostridia were predominant in the feces of normal individuals. The class Clostridia includes short-chain fatty acid-producing bacteria, important for the balance between regulatory T cells and helper T type 17 (Th17) cells. It is possible that the bacterial compositional alteration causes low intestinal short-chain fatty acid concentrations, leading to skewed immune functions in patients with BD.

METHODS

To test the hypothesis, we examined species composition and gene functions from the 16S rRNA data by utilizing PICRUSt software.

RESULTS

We have shown that relative abundance of Eggerthella lenta, Acidaminococcus species, Lactobacillus mucosae, Bifidobacterium bifidum, Lactobacillus iners, Streptococcus species, and Lactobacillus salivarius increased significantly in patients with BD. Relative abundance of Megamonas hypermegale, Butyrivibrio species, Streptococcus infantis, and Filifactor species increased significantly in normal individuals compared with BD patients. In the functional annotation analysis by PICRUSt, we found prevalent gene functions of the pentose phosphate pathway and the inosine monophosphate biosynthesis in patients with BD. The data suggested that BD gut microbes altered nucleic acid and fatty acid synthesis.

CONCLUSIONS

These compositional and functional alterations of gut microbes may accompany unfavorable molecular exchanges between intestinal immunocompetent cells and gut microbes, and these interactions may have an association with the immune aberration in patients with BD.

Critical regulation of Th17 cell differentiation by serum amyloid-A signalling in Behcet's disease

The current understandings on cellular and molecular biology suggest that Th17 axis plays a pivotal role in Behcet's disease (BD) pathogenesis. Recently the role of serum amyloid-A (SAA) as a potential marker of disease activity in BD patients has been explored, and it has been reported that the occurrence of specific clinical features are significantly associated with high serum levels of this inflammatory mediator. The aim of this study was to investigate the cytokine-like activity of SAA in inducing Th17 differentiation from CD4 + T naive cells in BD. Purified peripheral monocytes from BD and healthy control (HC) were stimulated with SAA "in vitro", and secreted IL-8, TNF-α, IL-18, IFN-α, IFN-γ, IL-1β and IL-6 were measured using a Bio-Rad multiplex cytokine immunoassay. To assess Th17 differentiation, purified CD4 + T cells were challenged with anti-CD3/CD28 antibodies, while cultured with supernatant derived from SAA stimulated monocytes, and intracellular staining of IL-17A and IFN-γ was evaluated by flow-cytometry. Furthermore, peripheral blood mononuclear cells (PBMCs) were stimulated with SAA and transcript levels of RAR-related orphan nuclear receptor (ROR)-γt and IL-17A were assessed by Real-time PCR. Upon stimulation with SAA, monocytes obtained from both HC and BD groups released large amounts of IL-8, IL-6, TNF-α, IL-1β and IFN-α. Monocytes-derived supernatants from BD patients, but not HC, were capable of promoting Th17 but not Th1 differentiation from CD4 + T cells. However, SAA did not induce up-regulation of Th17 specific mRNA transcript such as IL-17A and (ROR)-γt in PBMCs from both HC and BD. In BD patients SAA induced Th17 polarization rather than Th1 differentiation from CD4 + T cells. These data suggest that a critical regulation of Th17 may be the functional link between acute SAA increase and the induction of Th17 mediated inflammatory response in BD.

Recurrent aphthous stomatitis may be a precursor or risk factor for specific cancers: A case-control frequency-matched study

BACKGROUND

Recurrent aphthous stomatitis (RAS) is considered a prophase symptom in patients with specific cancers. This study assessed the association between RAS and subsequent onset of cancer based on a nationwide population-based database in Taiwan.

MATERIALS AND METHODS

We selected study participants from the National Health Insurance Research Database from January 2000 to December 2008. Patients in the non-RAS cohort were matched to case study patients at a 1:1 ratio through frequency matching. All participants were followed up for at least 5 years, and those who received cancer diagnoses during follow-up were identified.

RESULTS

Among 52 307 patients with and 52 304 patients without RAS, the combined hazard ratio (HR) of all subsequent cancer cases was 1.3 (95% confidence interval [CI]: 1.25-1.35, P = 0). RAS diagnosis was associated with risk for cancers of the head and neck (aHR = 2, 95% CI: 1.8-2.3), colon (aHR = 1.2, 95% CI: 1.1-1.4), liver (aHR = 1.1, 95% CI: 1-1.3), pancreas (aHR = 1.4, 95% CI: 1.1-1.7), skin (aHR = 1.4, 95% CI: 1.2-1.7), breast (aHR = 1.2, 95% CI: 1.1-1.4), and prostate (aHR = 1.5, 95% CI: 1.3-1.8), as well as hematologic cancers (aHR = 1.6, 95% CI: 1.3-1.9). A higher risk was observed for male patients (aHR = 1.35, 95% CI: 1.28-1.42) than for female patients (aHR = 1.25, 95% CI: 1.18-1.31) with RAS.

CONCLUSIONS

RAS was associated with specific cancers. Susceptible RAS patients should be screened for specific cancers.

Influence of corticosteroid therapy on IL-18 and nitric oxide production during Behçet's disease

BACKGROUND AND AIMS

Behçet's disease (BD) is a chronic multisystemic inflammatory disease with complex etiopathogenesis. Th1-proinflammatory cytokines seem to be involved in its pathogenesis. Our current study aims to evaluate interleukin-18 (IL-18) and nitric oxide (NO) involvement in the development of different clinical manifestations of BD as well as to investigate the corticosteroid therapy effect on this production in Algerian patients.

METHODS

For this purpose, we evaluated in vivo and ex vivo IL-18, interferon-γ (IFN-γ) levels using ELISA and NO production by the Griess' method in naïve-active and corticosteroid-treated BD patients with different clinical manifestations. Additionally, we assessed CD40/CD40L expression by flow cytometrics assay in these groups of patients.

RESULTS AND DISCUSSION

Our results indicate that IL-18 and nitrite levels were higher in naïve-active BD patients. Interestingly, this high production differed according to the clinical manifestations and was associated with an increased risk of mucocutaneous and vascular involvement. Concerning corticosteroid treated-active BD patients, no difference was observed in this production between each clinical subgroup. However, IFN-γ levels increased in all categories of active patients. Interestingly, corticosteroid therapy reduced significantly these inflammatory mediators regardless of the clinical manifestations studied. In addition, the CD40/CD40L expression differed according to the clinical presentations.

CONCLUSION

Collectively, our results suggest that concomitant high production of IL-18 and NO in naïve-active BD patients is related to an increased risk of mucocutaneous lesions and vascular involvement. Moreover, the relationship between these two inflammatory markers could constitute a predictable tool of BD clinical presentations and an early factor of therapy efficiency.

Soluble CD40L is associated with increased oxidative burst and neutrophil extracellular trap release in Behçet's disease

Background

Studies have suggested that soluble factors in plasma from patients with active (aBD) and inactive (iBD) Behçet’s disease (BD) stimulate neutrophil function. Soluble CD40 ligand (sCD40L) is an important mediator of inflammation in BD. Its expression and effect on neutrophil oxidative burst and neutrophil extracellular trap (NET) release have not been characterized. In this study, we sought to investigate the role of plasma and the CD40L pathway on NET release and the oxidative burst profile in patients with aBD and iBD.

Methods

Neutrophils and peripheral blood mononuclear cells (PBMCs) were obtained from patients with aBD (n = 30), patients with iBD (n = 31), and healthy control subjects (HCs; n = 30). sCD40L plasma concentration was determined in individual samples. A pool of plasma for each group was created. In some experiments, plasma pools were treated with recombinant CD40 (rhCD40-muIg) for sCD40L blockade. NET release and H₂O₂/O₂⁻ production were determined after stimulation with phorbol 12-myristate 13-acetate, sCD40L, or plasma pool. Flow cytometric analysis was performed to evaluate the expression of (1) CD40, Mac-1, and phosphorylated NF-κB p65 on neutrophils and monocytes and (2) CD40L on activated T cells and platelets. CD40L gene expression in PBMCs was determined by qRT-PCR.

Results

sCD40L plasma levels were significantly higher in patients with iBD (median 17,234, range 2346–19,279 pg/ml) and patients with aBD (median 18,289, range 413–19,883 pg/ml) than in HCs (median 47.5, range 33.7–26.7 pg/ml; p < 0.001). NET release was constitutively increased in BD compared with HC. NET release and H₂O₂/O₂⁻ were higher after stimulation with sCD40L or BD plasma and decreased after sCD40L blockade. Mac-1 expression was constitutively increased in neutrophils of patients with aBD (88.7 ± 13.2% of cells) and patients with iBD (89.2 ± 20.1% of cells) compared with HC (27.1 ± 18.8% of cells; p < 0.01). CD40 expression on phagocytes and CD40L expression on platelets were similar in the three groups. PBMCs as well as nonactivated and activated CD4⁺ T cells from patients with BD showed higher CD40L expression.

Conclusions

Plasma from patients with aBD exerts a stimulus on NET release and oxidative burst, probably induced by sCD40L.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-017-1443-5) contains supplementary material, which is available to authorized users.

IL-17 Production from T Helper 17, Mucosal-Associated Invariant T, and γδ Cells in Tuberculosis Infection and Disease

IL-17-producing cells have been shown to be important in the early stages of Mycobacterium tuberculosis (Mtb) infection in animal models. However, there are very little data on the role of IL-17 in human studies of tuberculosis (TB). We recruited TB patients and their highly exposed contacts who were further categorized based on results from an IFN-γ-release assay (IGRA): (1) IGRA positive (IGRA+) at recruitment (latently TB infected), (2) IGRA negative (IGRA-) at recruitment and 6 months [non-converters (NC)], and (3) IGRA- at recruitment and IGRA+ at 6 months (converters). Whole blood was stimulated with mycobacterial antigens and analyzed using T helper (Th) 17 multiplex cytokine assays. Th17, Vγ9Vδ2+, and CD161++Vα7.2+ mucosal-associated invariant T (MAIT) cells were analyzed by flow cytometry. The majority of IL-17 was produced by CD26+CD4+ Th17 cells (median 71%) followed by γδ T cells (6.4%) and MAIT cells (5.8%). TB patients had a significantly lower proportion of Th17 cells and CD4+CD161+Vα7.2+ cells producing both IL-17 and IFN-γ compared to LTBI subjects. IGRA NC had significantly lower levels of CD26-CD4+ and CD8+ MAIT cells producing IL-17 compared to IGRA C but had significantly higher levels of IL-17A, IL-17F, IL-21, and IL-23 in ESAT-6/CFP-10-stimulated supernatants compared to IGRA C. These data provide new insights into the role of IL-17 and IL-17-producing cells at three key stages of the Mtb infection spectrum.

Behçet's disease risk association fine-mapped on the IL23R-IL12RB2 intergenic region in Koreans

Background

Behçet’s disease (BD) susceptibility had been associated with single-nucleotide polymorphisms (SNPs) in IL23R–IL12RB2, IL10, STAT4, or ERAP1 locus in Japanese, Turkish, Chinese, and other populations, but not in a Korean genome-wide association study (GWAS). We aimed to fine-map BD risk association of these four loci using extensive imputation and additional genotyping for replication.

Methods

In the discovery phase, 369 patients with BD enrolled in the previous Korean GWAS and 2000 controls retrieved from a population-based cohort of healthy Koreans were imputed for their genotypes of all SNPs in the four loci using the Asian data of the 1000 Genomes Project as reference. For genotype imputation of ERAP1 SNPs, the adjacent ERAP2 SNPs were also covered. For the 10 most significantly associated SNPs (8 imputed and 2 GWAS-genotyped), an additional 84 patients with BD and 283 healthy controls were genotyped for replication. The results from the discovery and replication phases were pooled for meta-analysis using the Mantel-Haenszel test to estimate the odds ratio (OR) and 95% confidence interval (CI).

Results

An IL23R–IL12RB2 intergenic SNP rs1495965 was significantly associated with BD risk (OR (95% CI) = 1.5 (1.3, 1.7), P = 2.5 × 10⁻⁷) in the pooled meta-analysis of the discovery (1.4 (1.2, 1.7), P = 4.9 × 10⁻⁷) and replication (1.9 (1.3, 2.6), P = 6.0 × 10⁻⁴) phases. BD risk association was fine-mapped on the intergenic region rather than the two flanking genes, as rs1495966 and rs4655535, almost perfectly correlated with rs1495965 (r² = 0.99), were also located in the same intergenic region. Consistent with previous reports, the P values tended to be lower within IL23R than IL12RB2. On the other hand, several IL10 SNPs were suggested for association in the discovery phase but all failed in the replication phase. No SNP in ERAP1–ERAP2 and STAT4 was suggested even in the discovery phase.

Conclusions

BD susceptibility association was fine-mapped on the intergenic region between IL23R and IL12RB2 as marked by three correlated SNPs, rs1495965, rs1495966, and rs4655535.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-017-1435-5) contains supplementary material, which is available to authorized users.

Is Behçet's disease a 'class 1-opathy'? The role of HLA-B*51 in the pathogenesis of Behçet's disease

The association between carriage of the human leucocyte antigen (HLA)-B*51 allele and development of Behçet's disease (BD) has been known since the early 1970s, but the exact mechanisms responsible for its role in pathogenesis remain much-debated. In an effort to explain the disease process, it has been suggested that BD constitutes one of a newly termed group of diseases, the 'MHC-I-opathies'. Other MHC-I-opathies include ankylosing spondylitis and HLA-B*27-associated spondyloarthropathies and HLA-C*0602-associated skin psoriasis. Recent work analysing the peptidome of HLA-B*51 suggests that altered peptide presentation by HLA-B*51 is vital to the disease process. In this review, we argue that immune receptor interactions with HLA-B*51 or the HLA-B*51-peptide complex could lead to development of inflammation in BD. The evidence for CD8⁺ T cell involvement is weak, and based on emerging studies it seems more likely that natural killer (NK) or other cell interactions, perhaps mediated by leucocyte immunoglobulin-like receptor (LILR) or killer immunoglobulin-like receptor (KIR) receptors, are culpable in pathogenesis. HLA misfolding leading directly to inflammation is another hypothesis for BD pathogenesis that deserves greater investigation. Ultimately, greater understanding of HLA-B*51's unique role in BD will probably lead to improved development of therapeutic strategies.

TH1 signatures are present in the lower airways of children with severe asthma, regardless of allergic status

BACKGROUND

The pathogenesis of severe asthma in childhood remains poorly understood.

OBJECTIVE

We sought to construct the immunologic landscape in the airways of children with severe asthma.

METHODS

Comprehensive analysis of multiple cell types and mediators was performed by using flow cytometry and a multiplex assay with bronchoalveolar lavage (BAL) specimens (n = 68) from 52 highly characterized allergic and nonallergic children (0.5-17 years) with severe treatment-refractory asthma. Multiple relationships were tested by using linear mixed-effects modeling.

RESULTS

Memory CCR5⁺ T_H1 cells were enriched in BAL fluid versus blood, and pathogenic respiratory viruses and bacteria were readily detected. IFN-γ⁺IL-17⁺ and IFN-γ^-IL-17⁺ subsets constituted secondary T_H types, and BAL fluid CD8⁺ T cells were almost exclusively IFN-γ⁺. The T_H17-associated mediators IL-23 and macrophage inflammatory protein 3α/CCL20 were highly expressed. Despite low T_H2 numbers, T_H2 cytokines were detected, and T_H2 skewing correlated with total IgE levels. Type 2 innate lymphoid cells and basophils were scarce in BAL fluid. Levels of IL-5, IL-33, and IL-28A/IFN-λ2 were increased in multisensitized children and correlated with IgE levels to dust mite, ryegrass, and fungi but not cat, ragweed, or food sources. Additionally, levels of IL-5, but no other cytokine, increased with age and correlated with eosinophil numbers in BAL fluid and blood. Both plasmacytoid and IgE⁺FcεRI⁺ myeloid dendritic cells were present in BAL fluid.

CONCLUSIONS

The lower airways of children with severe asthma display a dominant T_H1 signature and atypical cytokine profiles that link to allergic status. Our findings deviate from established paradigms and warrant further assessment of the pathogenicity of T_H1 cells in patients with severe asthma.

Th17-Inducing Cytokines IL-6 and IL-23 Are Crucial for Granuloma Formation during Experimental Paracoccidioidomycosis

Paracoccidioidomycosis (PCM), a chronic granulomatous disease caused by the thermally dimorphic fungus Paracoccidioides brasiliensis and Paracoccidioides lutzii, has the highest mortality rate among systemic mycosis. The T helper 1-mediated immunity is primarily responsible for acquired resistance during P. brasiliensis infection, while susceptibility is associated with Th2 occurrence. Th17 is a population of T CD4⁺ cells that, among several chemokines and cytokines, produces IL-17A and requires the presence of IL-1, IL-6, and TGF-β for differentiation in mice and IL-23 for its maintenance. Th17 has been described as an arm of the immune system that enhances host protection against several bacterial and fungal infections, as Pneumocystis carinii and Candida albicans. In this study, we aimed to evaluate the Th17 immune response and the role of Th17-associated cytokines (IL-6, IL-23, and IL-17A) during experimental PCM. First, we observed that P. brasiliensis infection [virulent yeast strain 18 of P. brasiliensis (Pb18)] increased the IL-17A production in vitro and all the evaluated Th17-associated cytokines in the lung tissue from C57BL/6 wild-type mice. In addition, the deficiency of IL-6, IL-23, or IL-17 receptor A (IL-17RA) impaired the compact granuloma formation and conferred susceptibility during infection, associated with reduced tumor necrosis factor-α, IFN-γ, and inducible nitric oxide synthase enzyme expression. Our data suggest that IL-6 production by bone marrow-derived macrophages (BMDMs) is important to promote the Th17 differentiation during Pb18 infection. In accordance, the adoptive transfer of BMDMs from C57BL/6 to infected IL-6^-/- or IL-17RA^-/- mice reduced the fungal burden in the lungs compared to nontransferred mice and reestablished the pulmonary granuloma formation. Taken together, these results suggest that Th17-associated cytokines are involved in the modulation of immune response and granuloma formation during experimental PCM.

Roles of interleukin-17 in uveitis

Th17 cells, a CD4+ T-cell subset, produce interleukin (IL)-17, a pro-inflammatory cytokine that has been shown to be involved in several forms of infectious and noninfectious uveitis. Here, we explore the roles of this IL in uveitic disorders as well as in experimental autoimmune uveitis, the possible pathogenic implications of several cytokines associated with IL-17 and analyze the current outcomes and goals for drugs aiming for the IL-17 pathway.

The Role of Th17 Cells in the Pathogenesis of Behcet's Disease

Behcet's disease (BD) is a polysymptomatic and recurrent systemic vasculitis with a chronic course and unknown cause. The pathogenesis of BD has not been fully elucidated; however, BD has been considered to be a typical Th1-mediated inflammatory disease, characterized by elevated levels of Th1 cytokines such as IFN-γ, IL-2, and TNF-α. Recently, some studies reported that Th17-associated cytokines were increased in BD; thus, Th17 cells and the IL17/IL23 pathway may play important roles in the pathogenesis of BD. In this chapter, we focus on the pathogenic role of Th17 cells in BD.

Enhancement of Th1/Th17 inflammation by TRIM21 in Behçet's disease

The etiology of Behçet's disease (BD), a chronic, multisystemic autoinflammatory and autoimmune disease, remains unknown; however, researchers have postulated that infectious agents, such as herpes simplex virus, are significant triggering factors of BD. Tripartite motif-containing (TRIM) proteins exhibit antiviral properties, mediating antiviral defense mechanisms. The purpose of this study was to investigate TRIM21 protein expression in the monocytes of BD patients and to identify the role of TRIM21 in immune dysregulation in BD. In this study, the expression of TRIM21 and related molecules, including interferon regulatory factor 8 (IRF8), was analyzed in monocytes from BD patients. Functional analyses using small interfering RNA and co-culture with responder T cells were performed to examine the pathological role of TRIM21 in BD. Peripheral blood monocytes from BD patients showed increased TRIM21 expression and decreased IRF8 expression compared with that in monocytes from healthy controls. TRIM21 was found to decrease IRF8 expression. BD monocytes facilitated Th1 and Th17 differentiation of co-cultured T cells, and knock-down of TRIM21 expression by small interfering RNA inhibited this differentiation. In conclusion, TRIM21 played a pivotal role in regulating the secretion of proinflammatory cytokines in monocytes of BD patients.

Th17-Inducing Conditions Lead to in vitro Activation of Both Th17 and Th1 Responses in Behcet's Disease

OBJECTIVES

Interleukin-17 (IL-17) has been associated with the pathogenesis of various autoimmune/inflammatory diseases. The aim of this study was to investigate the expression of Th17-related immunity in an innate immunity-dominated vasculitis, namely Behcet's disease (BD).

METHODS

Peripheral blood mononuclear cells from 37 patients (age: 38.5 ± 9.8 years) with BD, and 25 healthy controls (HC) (age: 39.1 ± 9.3 years), were cultured in Th17-inducing conditions (IL-6, Phytohemagglutinin (PHA), IL-1β, and IL-23) for 6 days. Cultured cells were stained with CD4, CD8, CD3, TCR gamma/delta, CD19, interferon-γ (IFN-γ), and IL-17 antibodies to determine the intracellular cytokine secretion by flow cytometry.

RESULTS

IL-17 expression by CD8+ and γδ+ T cells was higher in BD compared to HC (p = 0.004, p = 0.003, respectively). No differences were observed between the groups in the IL-17 production by B cells. Under Th17-inducing conditions, production of IFN-γ by CD4+, CD8+, and γδ+ T cells was also higher in BD compared to HC (p < 0.05 in all).

CONCLUSION

Our results suggest that under Th17-stimulating conditions, T cells express both IL-17 and IFN-γ in BD. More prominent IL-17 and IFN-γ production by all lymphocyte subsets in BD might be associated with the increased innate responses, early tissue neutrophil infiltrations and late adaptive immunity in BD.

Circulating NK cells and their subsets in Behçet's disease

Behçet's disease (BD) is an autoinflammatory, chronic relapsing/remitting disease of unknown aetiology with both innate and acquired immune cells implicated in disease pathogenesis. Peripheral blood natural killer (NK) cells and their CD56^Dim /CD56^Bright subsets were surface phenotyped using CD27 and CD16 surface markers in 60 BD patients compared to 60 healthy controls (HCs). Functional potential was assessed by production of interferon (IFN)-γ, granzyme B, perforin and the expression of degranulation marker CD107a. The effects of disease activity (BD^Active versus BD^Quiet ) and BD medication on NK cells were also investigated. Peripheral blood NK cells (P < 0·0001) and their constituent CD56^Dim (P < 0·0001) and CD56^Bright (P = 0·0015) subsets were depleted significantly in BD patients compared to HCs, and especially in those with active disease (BD^Active ) (P < 0·0001). BD patients taking azathioprine also had significantly depleted NK cells compared to HCs (P < 0·0001). A stepwise multivariate linear regression model confirmed BD activity and azathioprine therapy as significant independent predictor variables of peripheral blood NK percentage (P < 0·001). In general, CD56^Dim cells produced more perforin (P < 0·0001) and granzyme B (P < 0·01) expressed higher CD16 levels (P < 0·0001) compared to CD56^Bright cells, confirming their increased cytotoxic potential with overall higher NK cell CD107a expression in BD compared to HCs (P < 0·01). Interestingly, IFN-γ production and CD27 expression were not significantly different between CD56^Dim /CD56^Bright subsets. In conclusion, both BD activity and azathioprine therapy have significant independent depletive effects on the peripheral blood NK cell compartment.

Cytotoxic Th1 and Th17 cells infiltrate the intestinal mucosa of Behcet patients and exhibit high levels of TNF-α in early phases of the disease

BACKGROUND

Gastrointestinal involvement is one of the most serious in Behçet disease, potentially leading to severe complications. Aim of this study was to investigate at mucosal level the T-cell responses in Behçet patients with early intestinal involvement.

METHODS

We isolated T cells from intestinal mucosa of 8 patients with intestinal symptoms started within 6 months. T lymphocytes were cloned and analyzed for surface phenotype and cytokines production.

RESULTS

We obtained 382 T-cell clones: 324 were CD4+ and 58 were CD8+. Within the 324 CD4+ clones, 195 were able to secrete IFN-γ and TNF-α, but not IL-4, nor IL-17 thus showing a polarized Th1 profile, whereas CD4 clones producing both IFN-γ and IL-17 (Th1/Th17 profile) were 79. Likewise, the number of CD8 clones producing type 1 cytokines was higher than those of CD8 clones producing both type 1 and 2 cytokines.Almost all intestinal-derived T-cell clones expressed perforin-mediated cytotoxicity and Fas-Fas Ligand-mediated pro-apoptotic activity.

CONCLUSIONS

Our results indicate that in the early stages of the disease, both Th1 and Th17 cells drive inflammation leading to mucosal damage via abnormal and long-lasting cytokines production as well as via both perforin- and Fas-Fas ligand-mediated cytotoxicity. Finally, all the T cells at mucosal level were able to produce large amount of TNF-α, suggesting that its production is a property of intestinal T cells of patients with early active intestinal disease. These results support the therapy with anti-TNF-α agents and suggest the use of anti-IL-17 monoclonal antibodies in Behçet patients with early intestinal involvement.

Functional impairment of infiltrating T cells in human colorectal cancer

T cells play a crucial role in preventing the growth and spread of colorectal cancer (CRC). However, immunotherapies against CRC have only shown limited success, which may be due to lack of understanding about the effect of the local tumor microenvironment (TME) on T cell function. The goal of this study was to determine whether T cells in tumor tissue were functionally impaired compared to T cells in non-tumor bowel (NTB) tissue from the same patients. We showed that T cell populations are affected differently by the TME. In the tumor, T cells produced more IL-17 and less IL-2 per cell than their counterparts from NTB tissue. T cells from tumor tissue also had impaired proliferative ability compared to T cells in NTB tissue. This impairment was not related to the frequency of IL-2 producing T cells or regulatory T cells, but T cells from the TME had a higher co-expression of inhibitory receptors than T cells from NTB. Overall, our data indicate that T cells in tumor tissue are functionally altered by the CRC TME, which is likely due to cell intrinsic factors. The TME is therefore an important consideration in predicting the effect of immune modulatory therapies.

Mucosal Lesions in an Allergy Practice

The diagnosis and treatment of mucosal disease with an allergic pathogenesis are challenging. Oral allergy is often a hypersensitivity reaction with variable symptoms and physical exam findings. Clinical diagnosis requires a history of prior allergen exposure, a delay from exposure to clinical findings, and improvement following allergen removal. The past decades have seen great contributions to the field of oral allergy. The aim of this review is to provide an approach to the diagnosis and treatment of oral dermatologic disease with a focus on diseases with an investigated allergic pathogenesis.

The potential of genetically guided treatment in Behçet's disease

Continuous identification of specific targets and candidate genes together with novel approaches offers new promises for the future of gene therapy design in Behçet's disease (BD). Personalized medicine based on pharmacogenomics is being developed at the clinical stage to improve treatment response. Screening the whole gene and regulatory regions is important when searching for novel variants associated with such complex diseases. Different host genetic factors play significant roles in susceptibility to BD. Thus, identifying these genes responsible for susceptibility and resistance to BD may offer a notable contribution toward understanding its pathogenesis, and may lead to the development of novel prophylactic and treatment strategies. Evidenced-based treatment strategy is recommended for the management in BD patients. This review sheds light on the immunopathogenesis and pharmacogenetics of BD with special attention to the treatment targeting gene polymorphisms. In conclusion, the potential of genetically guided treatment in BD takes us back to the future for an accurate management strategy of this serious rheumatic disease. The ongoing discovery of pivotal genes related to the susceptibility, manifestations, disease activity and treatment options provide substantial hope to the reduced frequency of BD, effective control and improvement in the prognosis. Targeted gene therapy could be a leading option in the treatment armamentarium of BD.