Notch Signaling During T Helper 2 Cell-Mediated Inflammation in Allergic Asthma

Enhanced activation of T helper-2 (Th2) cells producing Th2-cytokines (IL-4/IL-5/IL-13) explains many hallmarks of allergic asthma, including eosinophilic airway inflammation and bronchial hyperreactivity. Th2 cell differentiation is thought to be instructed by interaction of Notch on the T cell surface with its ligand Jagged on dendritic cells (DCs). Therefore, we studied the role of Notch signaling in allergic airway inflammation in vivo. In acute and chronic mouse models of house dust mite (HDM)-mediated allergic asthma, we found that expression of Notch and its nuclear effector RBPJκ in T cells is essential for disease development. Our findings suggest that Notch signaling is involved in migration of Th2 cells into the lung. Transgenic overexpression of the key Th2 transcription factor Gata3 in the absence of Notch was not sufficient to induce allergic inflammation, indicating that Notch signaling has additional downstream targets next to Gata3. Mice lacking Jagged1/2 on DCs, T cells or lymph node stromal cells still developed HDM-driven airway inflammation. Importantly, hallmarks of asthma could be suppressed by the Notch inhibitory peptide SAHM1 – which interferes with RBPJκ function - but not by a control peptide. Finally, we obs

Notch signaling in T cells is essential for allergic airway inflammation, but expression of the Notch ligands Jagged 1 and Jagged 2 on dendritic cells is dispensable

__Background:__ Allergic asthma is characterized by a TH2 response induced by dendritic cells (DCs) that present inhaled allergen. Although the mechanisms by which they instruct TH2 differentiation are still poorly understood, expression of the Notch ligand Jagged on DCs has been implicated in this process. __Objective:__ We sought to establish whether Notch signaling induced by DCs is critical for house dust mite (HDM)-driven allergic airway inflammation (AAI) in vivo. __Methods:__ The induction of Notch ligand expression on DC subsets by HDM was quantified by using quantitative real-time PCR. We used an HDM-driven asthma mouse model to compare the capacity of Jagged 1 and Jagged 2 single- and double-deficient DCs to induce AAI. In addition, we studied AAI in mice with a T cell-specific deletion of recombination signal-binding protein for immunoglobulin Jκ region (RBPJκ), a downstream effector of Notch signaling. __Results:__ HDM exposure promoted expression of Jagged 1, but not Jagged 2, on DCs. In agreement with published findings, in vitro-differentiated and HDM-pulsed Jagged 1 and Jagged 2 double-deficient DCs lacked the capacity to induce AAI. However, after in vivo intranasal sensitization and challenge with HDM, DC-specific Jagged 1 or Jagged 2 single- or double-deficient mice had eosinophilic airway inflammation and a TH2 cell activation phenotype that was not different from that in control littermates. In contrast, RBPJκ-def

Serum Immune Profiling in Paediatric Crohn's Disease Demonstrates Stronger Immune Modulation With First-Line Infliximab Than Conventional Therapy and Pre-Treatment Profiles Predict Clinical Response to Both Treatments

BACKGROUND: Despite its efficacy, rational guidance for starting/stopping first-line biologic treatment in individual paediatric Crohn's disease [CD] patients is needed. We assessed how serum immune profiles before and after first-line infliximab [FL-IFX] or conventional [CONV] induction therapy associate with disease remission at week 52. METHODS: Pre- [n = 86], and 10-14-week post-treatment [n = 84] sera were collected from patients with moderate-to-severe paediatric CD in the TISKids trial, randomized to FL-IFX [n = 48; five 5-mg/kg infusions over 22 weeks] or CONV [n = 43; exclusive enteral nutrition or oral prednisolone]; both groups received azathioprine maintenance. The relative concentrations of 92 inflammatory proteins were determined with Olink Proteomics; fold changes [FC] with |log2FC| &gt; 0.5 after false discovery rate adjustment were considered significant. RESULTS: FL-IFX modulated a larger number of inflammatory proteins and induced stronger suppression than CONV; 18/30 proteins modulated by FL-IFX were not regulated by CONV. Hierarchical clustering based on IFX-modulated proteins at baseline revealed two clusters of patients: CD-hi patients had significantly higher concentrations of 23/30 IFX-modulated proteins [including oncostatin-M, TNFSF14, HGF and TGF-α], and higher clinical disease activity, C-reactive protein and blood neutrophils at baseline than CD-lo patients. Only 24% of CD-hi FL-IFX-treated patients maintained remission without escalation at week 52 vs 58% of CD-lo FL-IFX-treated patients. Similarly, 6% of CD-hi CONV-treated patients achieved remission vs 20% of CONV-treated CD-lo patients. Clustering based on immune profiles post-induction therapy did not relate to remission at week 52. CONCLUSION: FL-IFX leads to stronger reductions and modulates more immune proteins than CONV. Stratification on pre-treatment profiles of IFX-modulated proteins directly relates to maintenance of remission without treatment escalation. TRIAL REGISTRATION NUMBER: NCT02517684.</p

International prospective observational study investigating the disease course and heterogeneity of paediatric-onset inflammatory bowel disease: the protocol of the PIBD-SETQuality inception cohort study

INTRODUCTION: Patients with paediatric-onset inflammatory bowel disease (PIBD) may develop a complicated disease course, including growth failure, bowel resection at young age and treatment-related adverse events, all of which can have significant and lasting effects on the patient's development and quality of life. Unfortunately, we are still not able to fully explain the heterogeneity between patients and their disease course and predict which patients will respond to certain therapies or are most at risk of developing a more complicated disease course. To investigate this, large prospective studies with long-term follow-up are needed. Currently, no such European or Asian international cohorts exist. In this international cohort, we aim to evaluate disease course and which patients are most at risk of therapy non-response or development of complicated disease based on patient and disease characteristics, immune pathology and environmental and socioeconomic factors. METHODS AND ANALYSIS: In this international prospective observational study, which is part of the PIBD Network for Safety, Efficacy, Treatment and Quality improvement of care (PIBD-SETQuality), children diagnosed with inflammatory bowel disease <18 years are included at diagnosis. The follow-up schedule is in line with standard PIBD care and is intended to continue up to 20 years. Patient and disease characteristics, as well as results of investigations, are collected at baseline and during follow-up. In addition, environmental factors are being assessed (eg, parent's smoking behaviour, dietary factors and antibiotic use). In specific centres with the ability to perform extensive immunological analyses, blood samples and intestinal biopsies are being collected and analysed (flow cytometry, plasma proteomics, mRNA expression and immunohistochemistry) in therapy-naïve patients and during follow-up. ETHICS AND DISSEMINATION: Medical ethical approval has been obtained prior to patient recruitment for all sites. The results will be disseminated through peer-reviewed scientific publications. TRIAL REGISTRATION NUMBER: NCT03571373

Dissecting the Heterogeneity in T-Cell Mediated Inflammation in IBD

Infiltration of the lamina propria by inflammatory CD4+ T-cell populations is a key characteristic of chronic intestinal inflammation. Memory-phenotype CD4+ T-cell frequencies are increased in inflamed intestinal tissue of IBD patients compared to tissue of healthy controls and are associated with disease flares and a more complicated disease course. Therefore, a tightly controlled balance between regulatory and inflammatory CD4+ T-cell populations is crucial to prevent uncontrolled CD4+ T-cell responses and subsequent intestinal tissue damage. While at steady state, T-cells display mainly a regulatory phenotype, increased in Th1, Th2, Th9, Th17, and Th17.1 responses, and reduced Treg and Tr1 responses have all been suggested to play a role in IBD pathophysiology. However, it is highly unlikely that all these responses are altered in each individual patient. With the rapidly expanding plethora of therapeutic options to inhibit inflammatory T-cell responses and stimulate regulatory T-cell responses, a crucial need is emerging for a robust set of immunological assays to predict and monitor therapeutic success at an individual level. Consequently, it is crucial to differentiate dominant inflammatory and regulatory CD4+ T helper responses in patients and relate these to disease course and therapy response. In this review, we provide an overview of how intestinal CD4+ T-cell responses arise, discuss the main phenotypes of CD4+ T helper responses, and review how they are implicated in IBD

Notch signaling in T helper cell subsets: Instructor or unbiased amplifier?

textabstractFor protection against pathogens, it is essential that naïve CD4+ T cells differentiate into specific effector T helper (Th) cell subsets following activation by antigen presented by dendritic cells (DCs). Next to T cell receptor and cytokine signals, membrane-bound Notch ligands have an important role in orchestrating Th cell differentiation. Several studies provided evidence that DC activation is accompanied by surface expression of Notch ligands. Intriguingly, DCs that express the delta-like or Jagged Notch ligands gain the capacity to instruct Th1 or Th2 cell polarization, respectively. However, in contrast to this model it has also been hypothesized that Notch signaling acts as a general amplifier of Th cell responses rather than an instructive director of specific T cell fates. In this alternative model, Notch enhances proliferation, cytokine production, and anti-apoptotic signals or promotes co-stimulatory signals in T cells. An instructive role for Notch ligand expressing DCs in the induction of Th cell differentiation is further challenged by evidence for the involvement of Notch signaling in differentiation of Th9, Th17, regulatory T cells, and follicular Th cells. In this review, we will discuss the two opposing models, referred to as the "instructive" and the "unbiased amplifier" model. We highlight both the function of different Notch receptors on CD4+ T cells and the impact of Notch ligands on antigen-presenting cells

T cells are necessary for ILC2 activation in house dust mite-induced allergic airway inflammation in mice

Allergic asthma is a chronic inflammation of the airways mediated by an adaptive type 2 immune response. Upon allergen exposure, group 2 innate lymphoid cells (ILC2s) can be rapidly activated and represent an early innate source of IL-5 and IL-13. Here, we used a house dust mite (HDM)-driven asthma mouse model to study the induction of ILC2s in allergic airway inflammation. In BALF, lungs, and lymph nodes, ILC2 activation is critically dependent on prior sensitization with HDM. Importantly, T cells are required for ILC2 induction, whereby T-cell activation precedes ILC2 induction. During HDM-driven allergic airway inflammation the accumulation of ILC2s in BALF is IL-33 independent, although infiltrating ILC2s produce less cytokines in Il33(-/-) mice. Transfer of in vitro polarized OVA-specific OT-II Th2 cells alone or in combination with Th17 cells followed by OVA and HDM challenge is not sufficient to induce ILC2, despite significant eosinophilic inflammation and T-cell activation. In this asthma model, ILC2s are therefore not an early source of Th2 cytokines, but rather contribute to type 2 inflammation in which Th2 cells play a key role. Taken together, ILC2 induction in HDM-mediated allergic airway inflammation in mice critically depends on activation of T cells

Notch signaling in T cells is essential for allergic airway inflammation, but expression of the Notch ligands Jagged 1 and Jagged 2 on dendritic cells is dispensable

Allergic asthma is characterized by a TH2 response induced by dendritic cells (DCs) that present inhaled allergen. Although the mechanisms by which they instruct TH2 differentiation are still poorly understood, expression of the Notch ligand Jagged on DCs has been implicated in this process. We sought to establish whether Notch signaling induced by DCs is critical for house dust mite (HDM)-driven allergic airway inflammation (AAI) in vivo. The induction of Notch ligand expression on DC subsets by HDM was quantified by using quantitative real-time PCR. We used an HDM-driven asthma mouse model to compare the capacity of Jagged 1 and Jagged 2 single- and double-deficient DCs to induce AAI. In addition, we studied AAI in mice with a T cell-specific deletion of recombination signal-binding protein for immunoglobulin Jκ region (RBPJκ), a downstream effector of Notch signaling. HDM exposure promoted expression of Jagged 1, but not Jagged 2, on DCs. In agreement with published findings, in vitro-differentiated and HDM-pulsed Jagged 1 and Jagged 2 double-deficient DCs lacked the capacity to induce AAI. However, after in vivo intranasal sensitization and challenge with HDM, DC-specific Jagged 1 or Jagged 2 single- or double-deficient mice had eosinophilic airway inflammation and a TH2 cell activation phenotype that was not different from that in control littermates. In contrast, RBPJκ-deficient mice did not experience AAI and airway hyperreactivity. Our results show that the Notch signaling pathway in T cells is crucial for the induction of TH2-mediated AAI in an HDM-driven asthma model but that expression of Jagged 1 or Jagged 2 on DCs is not require