The TLR9 Agonist Cobitolimod Induces IL10-Producing Wound Healing Macrophages and Regulatory T Cells in Ulcerative Colitis.

BACKGROUND AND AIMS: The topically applied Toll-like receptor 9 [TLR9] agonist cobitolimod is a first-in-class DNA-based oligonucleotide with demonstrated therapeutic efficacy in clinical trials with ulcerative colitis [UC] patients. We here characterized its anti-inflammatory mechanism in UC. METHODS: Luminal cobitolimod administration was evaluated in an experimental dextran sodium sulfate [DSS]-induced colitis model. Cultured blood and mucosal cells from UC patients were treated with cobitolimod and analysed via microarray, quantitative real-time PCR, ELISA and flow cytometry. Intestinal slides of cobitolimod-treated UC patients were analysed by immunohistochemistry. RESULTS: Cobitolimod administration markedly suppressed experimental colitis activity, and microarray analyses demonstrated mucosal IL10 upregulation and suppression of IL17 signalling pathways. Cobitolimod treatment was associated with significant induction of mucosal IL10+Tr1 and Treg cells and suppression of Th17 cells. TLR9 knockout mice indicated that cobitolimod requires TLR9 signalling for IL10 induction. In UC patients, mucosal TLR9 levels correlated with severity of inflammation. Cobitolimod inhibited IL17A and IL17F, but increased IL10 and FoxP3 expression in cultured intestinal UC T cells. Cobitolimod-mediated suppression of intestinal IL17+T cells was abrogated by IL10 blockade. Furthermore, cobitolimod led to heightened IL10 production by wound healing macrophages. Immunohistochemistry in intestinal biopsies of cobitolimod-treated UC patients indicated increased presence of IL10+mononuclear and regulatory T cells, as well as reduction of IL17+cells. CONCLUSION: Activation of TLR9 via cobitolimod might represent a novel therapeutic approach in UC, as it suppresses Th17 cells and induces anti-inflammatory IL10+macrophages and regulatory T cells, thereby modifying the dysregulated intestinal cytokine balance. PODCAST: This article has an associated podcast which can be accessed at https://academic.oup.com/ecco-jcc/pages/podcast.

Clinical efficacy of the Toll-like receptor 9 agonist cobitolimod using patient-reported-outcomes defined clinical endpoints in patients with ulcerative colitis.

BACKGROUND: The Toll-like-receptor 9 (TLR-9) agonist cobitolimod (DIMS0150, Kappaproct®) is a promising therapeutic option for ulcerative colitis (UC) patients. AIMS: The objectives of this post-hoc analysis using the COLLECT study data was to investigate the clinical effects of cobitolimod using patient-reported-outcomes (PRO) defined endpoints. METHODS: Dual topical administration of cobitolimod was studied in a randomised, multicentre clinical trial named COLLECT in moderate-to-severe UC patients. Symptomatic remission (SR) was studied in 104 patients based on their e-diary records and was defined as absence of blood in stool and a mean daily stool frequency (SF) < 4. RESULTS: SR was achieved at week 4 in 17.1% of cobitolimod vs. 5.9% of placebo treated patients (p = 0.13), at week 8 in 35.7% vs. 17.6% (p = 0.07), and at week 12 in 38.6% vs. 17.6% (p = 0.04) of the patients, respectively. SR rates with cobitolimod and placebo in anti-TNFα experienced patients were smaller but with a broadly similar relative effect-size to anti-TNFα naïve patients. Clinical efficacy was higher in patients with moderate compared to severe disease. CONCLUSIONS: Application of the Toll-like-receptor 9 (TLR-9) agonist cobitolimod is able to induce remission as assessed by PRO measures in UC patients with moderate-to-severe activity as well as in anti-TNFα experienced and naïve patients supporting the overall efficacy of the substance.

Clinical Effects of a Topically Applied Toll-like Receptor 9 Agonist in Active Moderate-to-Severe Ulcerative Colitis.

BACKGROUND AND AIMS: Toll-like receptors [TLRs] are potential drug targets for immunomodulation. We determined the safety and efficacy of the TLR-9 agonist DNA-based immunomodulatory sequence 0150 [DIMS0150] in ulcerative colitis [UC] patients refractory to standard therapy. METHODS: In this randomized, double-blind, placebo-controlled trial, 131 patients with moderate-to-severe active UC were randomized to receive two single doses of the oligonucleotide DIMS0150 [30 mg] or placebo administered topically during lower GI endoscopy at baseline and Week 4. The primary endpoint was clinical remission, defined as Clinical Activity Index [CAI] ≤4, at Week 12. Secondary endpoints included mucosal healing and symptomatic remission of key patient-reported outcomes [absence of blood in stool and weekly stool frequency <35]. RESULTS: There was no statistical significant difference between the groups in the induction of clinical remission at Week 12, with 44.4% in the DIMS0150 group vs. 46.5% in the placebo group. However, the proportion of patients who achieved symptomatic remission was 32.1% in the DIMS0150 group vs. 14.0% in the placebo group at Week 4 [p = 0.020], and 44.4% vs. 27.9% at Week 8 [p = 0.061]. More patients on DIMS0150 compared with those on placebo had mucosal healing [34.6% vs. 18.6%; p = 0.09] and histological improvement regarding the Geboes score [30.9% vs. 9.3%; p = 0.0073] at Week 4. Significantly more patients on DIMS0150 were in clinical remission with mucosal healing at Week 4: 21% vs. 4.7% in the placebo group [p = 0.02]. DIMS0150 was well tolerated, and no safety signals compared with placebo were evident. CONCLUSIONS: Therapy with the topically applied TLR-9 agonist DIMS0150 is a promising and well-tolerated novel therapeutic option for treatment-refractory, chronic active UC patients, warranting further clinical trials.

Immunomodulatory oligonucleotides inhibit neutrophil migration by decreasing the surface expression of interleukin-8 and leukotriene B4 receptors.

Neutrophils play important roles in many inflammatory diseases. The migration of neutrophils to the inflammatory site is tightly regulated by specific chemokines, of which interleukin-8 (IL-8) and leukotriene B4 (LTB4 ) constitute key mediators by binding to the surface receptors CXCR1/2 and BLT1, respectively. Oligonucleotides (ODN) containing CpG motifs mediate potent immunomodulatory effects through binding to Toll-like receptor 9. So far, knowledge on how ODN can affect neutrophil migration during inflammation is lacking. This study demonstrates that several novel CpG ODN significantly down-regulate the surface expression of CXCR1/2 and BLT1. In addition, the ODN significantly blocked IL-8-induced and LTB4 -induced neutrophil migration in vitro, as well as leucocyte migration in vivo demonstrated in mice by intravital microscopy and in a model of airway inflammation. The down-regulation of CXCR1 is rapid, occurring 15 min after ODN stimulation, and can be mediated through an endosomally independent mechanism. Inhibition of the IL-8 and LTB4 pathways may provide new opportunities of therapeutic intervention using ODN to reduce neutrophil infiltration during inflammation.

Topical treatment with the Toll-like receptor agonist DIMS0150 has potential for lasting relief of symptoms in patients with chronic active ulcerative colitis by restoring glucocorticoid sensitivity.

BACKGROUND: Patients with chronic active ulcerative colitis (UC) are regarded as treatment failures and represent an area of high unmet medical need, as normally the only remaining option is colectomy. METHODS: We treated a total of eight chronic active severe UC outpatients with the immunomodulatory agent DIMS0150 as an add-on to current therapies. Seven patients received a single topical dose of 30 mg and one special case subject received three doses with 4 weeks between dosing occasions. All patients were classed as treatment failures and were elected for colectomy. Efficacy evaluation was determined in terms of colitis activity index, endoscopic improvement, and histologic disease activity assessed primarily at week 12 with a follow-up period of over 2 years. Glucocorticoid sensitivity was assayed by in vitro measurement of interleukin 6. RESULTS: All patients demonstrated a pronounced and rapid reduction in their colitis activity index within 1 week following a single intracolonic administration via colonoscope of the agent DIMS0150. Further improvements were evident at week 4, resulting in a clinical response rate for the single-dose treatment of 71%, with 43% in clinical remission. By week 12 the clinical response and remission rates had reached 82% and 71%, respectively. A follow-up period of over 2 years posttreatment indicated that all but one of the treated patients had avoided the need for colectomy, with the longest patient being in symptom-free remission for over 27 months. Treatment with DIMS0150 restored glucocorticoid sensitivity. CONCLUSIONS: DIMS0150 may have the potential to be an effective agent to treat chronic active UC patients with the prospect to avoid colectomy on a long-term basis and is currently the subject of a clinical phase III study (EudraCT number: 2011-003130-14).

Different types of in vitro generated human monocyte-derived dendritic cells release exosomes with distinct phenotypes.

Human in vitro generated dendritic cells and the exosomes they release are potential tools for the modulation of immune responses. Here, we characterized differently generated monocyte-derived dendritic cells (MDDCs) and their exosomes. Culturing of peripheral CD14+ cells from the same individuals with either interleukin (IL)-4 and granulocyte-macrophage colony-stimulating factor (GM-CSF) (conventional MDDCs) or alternatively with IL-4 and IL-3 generated immature MDDCs in 7 days. Fluorescence-activated cell sorting (FACS) analysis showed that the IL-4/IL-3-generated MDDCs had significantly lower percentages of CD1a+, CD40+ and CD80+ cells and a higher percentage of CD86+ cells as compared with conventional MDDCs. In addition, IL-4/IL-3-generated MDDCs had significantly higher densities of major histocompatibility complex (MHC) class I [human leucocyte antigen (HLA)-ABC], MHC class II (HLA-DR), CD11c and the tetraspanin CD81 as compared with conventional MDDCs. In a comparison of their ability to stimulate CD8+ T cells, we found that the IL-4/IL-3 MDDCs were slightly more efficient than the conventional MDDCs at inducing interferon (IFN)-gamma release in response to viral peptides. Exosome morphology was confirmed by electron microscopy and exosome phenotypes were analysed by flow cytometry and western blot. In comparison to exosomes from conventional MDDCs, exosomes from IL-4/IL-3-generated MDDCs showed significantly stronger signals for HLA-ABC, HLA-DR, CD11c, CD63 and CD81. Thus, phenotypically the exosomes largely reflected their MDDCs of origin. When exosomes were loaded with viral peptides, both types of exosomes induced IFN-gamma release from CD8+ T cells. Our findings might have significance for the development of DC- and exosome-based therapies.

B cell-derived exosomes can present allergen peptides and activate allergen-specific T cells to proliferate and produce TH2-like cytokines.

BACKGROUND: Exosomes are vesicles of 30 to 100 nm produced by inward budding of endosomal compartments and are released by a range of different cell types. Exosomes from antigen-presenting cells carry immunorelevant molecules like MHC class I and II and costimulatory molecules and thus are suggested to have a role in immune modulation. OBJECTIVE: To investigate the role of antigen-presenting cell derived exosomes in allergen presentation and T-cell stimulation. METHODS: Exosomes were isolated from supernatants of B-cell lines derived from patients with birch pollen allergy. The exosomes were characterized with regard to the expression of surface molecules by flow cytometry. Moreover, exosomes were loaded with T-cell-activating peptides from the major birch allergen Bet v 1, and binding was tested with ELISA. Loaded exosomes were used for stimulation of Bet v 1-specific T-cell lines. Cell proliferation and cytokine production were assessed. RESULTS: The exosomes had a phenotype typical of B cell-derived exosomes with expression of MHC, costimulatory molecules like CD86, tetraspanin proteins such as CD81, and CD19. Furthermore, B cell-derived exosomes bound Bet v 1-derived peptides and subsequently induced a dose-dependent T-cell proliferation. In addition to proliferation, T cells synthesized the cytokines IL-5 and IL-13 in response to peptide-loaded exosomes. CONCLUSION: These results demonstrate for the first time that exosomes isolated from B cells can present allergen-derived peptides and thereby induce T-cell proliferation and T(H)2-like cytokine production. CLINICAL IMPLICATIONS: Our data suggest that exosomes from B lymphocytes are an immunostimulatory factor in allergic immune responses.

Exosomes with immune modulatory features are present in human breast milk.

Breast milk is a complex liquid with immune-competent cells and soluble proteins that provide immunity to the infant and affect the maturation of the infant's immune system. Exosomes are nanovesicles (30-100 nm) with an endosome-derived limiting membrane secreted by a diverse range of cell types. Because exosomes carry immunorelevant structures, they are suggested to participate in directing the immune response. We hypothesized that human breast milk contain exosomes, which may be important for the development of the infant's immune system. We isolated vesicles from the human colostrum and mature breast milk by ultracentrifugations and/or immuno-isolation on paramagnetic beads. We found that the vesicles displayed a typical exosome-like size and morphology as analyzed by electron microscopy. Furthermore, they floated at a density between 1.10 and 1.18 g/ml in a sucrose gradient, corresponding to the known density of exosomes. In addition, MHC classes I and II, CD63, CD81, and CD86 were detected on the vesicles by flow cytometry. Western blot and mass spectrometry further confirmed the presence of several exosome-associated molecules. Functional analysis revealed that the vesicle preparation inhibited anti-CD3-induced IL-2 and IFN-gamma production from allogeneic and autologous PBMC. In addition, an increased number of Foxp3(+)CD4(+)CD25(+) T regulatory cells were observed in PBMC incubated with milk vesicle preparations. We conclude that human breast milk contains exosomes with the capacity to influence immune responses.

Direct exosome stimulation of peripheral human T cells detected by ELISPOT.

Exosomes from APC are nano-vesicles that can induce antigen-specific T cell responses and are presently explored as therapeutic tools in different clinical settings. Investigations of the capacity of exosomes to stimulate T cells in vitro have mostly been performed on T cell hybridomas, clones or lines. Whether exosomes can stimulate T cells directly or need the presence of dendritic cells (DC) is debated. We could detect exosome-induced antigen-specific CD8(+) T cell responses in peripheral blood from humans. Exosomes from monocyte-derived DC (MDDC) were loaded with a mix of 23 immunogenic peptides from EBV, CMV and influenza virus, and added to autologous peripheral CD8(+) T cells. IFN-gamma-producing cells were detected by enzyme-linked immunospot assay (ELISPOT). MDDC-exosomes induced IFN-gamma production in CD8(+) T cells without addition of DC. The response was exosome dose dependent, and dependent on exosomal MHC class I. Furthermore, we detected an enhanced T cell stimulatory capacity by exosomes from lipopolysaccharide-matured MDDC compared to exosomes from immature MDDC. Exosomes could also induce TNF-alpha production. These results show, for the first time, that exosomes can directly stimulate human peripheral CD8(+) T cells in an antigen-specific manner and that ELISPOT is a suitable method for detecting exosome-induced peripheral T cell responses. This system may provide a useful tool when developing exosomes as therapeutic agents.