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.

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).

The Malassezia sympodialis allergen Mala s 11 induces human dendritic cell maturation, in contrast to its human homologue manganese superoxide dismutase.

BACKGROUND: Recently, we identified a major Malassezia sympodialis allergen, Mala s 11, which displays a high degree of DNA sequence homology to human manganese superoxide dismutase (hMnSOD). In atopic eczema patients sensitized to M. sympodialis, hMnSOD can elicit eczematous reactions and positive skin prick tests, suggesting cross- reactivity to Mala s 11 based on molecular mimicry. The objective of the current study was to compare the influence of Mala s 11 and hMnSOD on human dendritic antigen-presenting cells. METHODS: Monocyte-derived dendritic cells (MDDCs) from healthy blood donors were co-cultured with recombinant Mala s 11 (rMala s 11), recombinant hMnSOD (rhMnSOD), lipopolysaccharide or cultured in medium alone. Phenotypic changes were analysed using flow cytometry and allogeneic lymphocyte proliferation assays. Cytokine release into culture supernatants was investigated using cytometric bead array. RESULTS: Whereas rhMnSOD did not affect the MDDC phenotype, rMala s 11 up-regulated the maturation marker CD83, the co-stimulatory molecules CD40, CD80, CD86 and HLA-DR to a similar extent as lipopolysaccharide. Furthermore, rMala s 11, but not rhMnSOD, induced significantly higher levels of TNF-alpha, IL-6, IL-8, IL-10 and IL-12p70 in the culture supernatants at 24 h in comparison with MDDCs cultured in medium alone. Finally, MDDCs pre-incubated with rMala s 11 induced a significantly higher proliferation of allogeneic CD14-depleted peripheral blood monocytes than MDDCs pre-incubated with rhMnSOD. CONCLUSION: Our results suggest that Mala s 11, but not hMnSOD, affects the immune response of healthy individuals through dendritic cell maturation and cytokine release. This indicates that dendritic cells possess the ability to distinguish between Mala s 11 and its human homologue MnSOD.