Glucocorticoids Induce Apoptosis in Human Monocytes: Potential Role of IL-1β

AbstractGlucocorticoids (GC) are potent anti-inflammatory and immunosuppressive agents that act on a variety of immune cells, including monocytes and macrophages. However, the exact cellular mechanisms underlying this anti-inflammatory capacity are still unknown. In our study, we determined the induction of apoptosis by GC in human monocytes. Peripheral blood monocytes were isolated by density centrifugation methods with a purity of &amp;gt;90% and were cultured in RPMI 1640 medium. Monocyte apoptosis was determined by four independent methods, including annexin-V staining, TUNEL, DNA-laddering, and typical morphology by means of transmission electron microscopy. TNF-α and IL-1β were measured by ELISA. GC receptor was blocked with mifepristone. Caspase 3 was inhibited with caspase-3 inhibitor (DEVD-CHO). Stimulation with different GC at therapeutic concentrations resulted in monocyte apoptosis in a time- and dose-dependent manner. Necrosis was excluded by propidium iodide staining. Proinflammatory cytokines such as IL-1β and TNF-α were down-regulated by GC treatment. Continuous treatment of monocytes with IL-1β, but not with TNF-α, could almost completely prevent GC-induced cell death. The addition of mifepristone or caspase-3 inhibitor could partially abrogate GC-induced apoptosis as well as GC-induced inhibition of IL-1β. This is the first study to demonstrate induction of apoptosis by GC in human monocytes. GC-induced monocyte apoptosis may be partially mediated through effects on IL-1β production. It is conceivable that GC exert their anti-inflammatory capacity in various diseases, at least in part, by the induction of apoptosis in monocytes.</jats:p

Role of the CD95/CD95 Ligand System in Glucocorticoid-Induced Monocyte Apoptosis

Abstract Glucocorticoids (GC) act as potent anti-inflammatory and immunosuppressive agents on a variety of immune cells. However, the exact mechanisms of their action are still unknown. Recently, we demonstrated that GC induce apoptosis in human peripheral blood monocytes. In the present study, we examined the signaling pathway in GC-induced apoptosis. Monocyte apoptosis was demonstrated by annexin V staining, DNA laddering, and electron microscopy. Apoptosis required the activation of caspases, as different caspase inhibitors prevented GC-induced cell death. In addition, the proteolytic activation of caspase-8 and caspase-3 was observed. In additional experiments, we determined the role of the death receptor CD95 in GC-induced apoptosis. CD95 and CD95 ligand (CD95L) were up-regulated in a dose- and time-dependent manner on the cell membrane and also released after treatment with GC. Costimulation with the GC receptor antagonist mifepristone diminished monocyte apoptosis as well as CD95/CD95L expression and subsequent caspase-8 and caspase-3 activation. In contrast, the caspase inhibitor N-acetyl-Asp-Glu-Val-Asp-aldehyde suppressed caspase-3 activation and apoptosis, but did not down-regulate caspase-8 activation and expression of CD95 and CD95L. Importantly, GC-induced monocyte apoptosis was strongly abolished by a neutralizing CD95L mAb. Therefore, our data suggest that GC-induced monocyte apoptosis is at least partially mediated by an autocrine or paracrine pathway involving the CD95/CD95L system.</jats:p

Lymphoid Precursors in Intestinal Cryptopatches Express CCR6 and Undergo Dysregulated Development in the Absence of CCR6

Abstract Small intestinal cryptopatches (CP) are the major anatomic site for extrathymic differentiation by precursors destined to become intestinal intraepithelial T lymphocytes (IEL). We found that mice deficient in CCR6 exhibited a 2.7-fold increase in the number of αβ TCR IEL, but little or no expansion of γδ TCR IEL. Among the αβ TCR IEL subsets, the CD4− CD8αα+ and CD4+ CD8αα+ subsets were preferentially expanded in CCR6 null mice. Because some CD8αα+ IEL can arise through extrathymic differentiation in CP, we investigated CCR6 expression by T lymphocyte precursors undergoing extrathymic differentiation in intestinal CP. In sections of CP, 50–60% of c-kit+ precursors were CCR6+. CD11c+ cells concentrated at the periphery of CP did not express CCR6. A subset of c-kit+, Lin− cells in lamina propria suspensions was CCR6+, but CCR6 was absent from c-kit+ precursors in bone marrow. CCR6 was absent from the vast majority of mature IEL. CCR6 is present on lymphocyte precursors in cryptopatches, expressed transiently during extrathymic IEL development, and is required for homeostatic regulation of intestinal IEL.</jats:p

I-CARE, a European Prospective Cohort Study Assessing Safety and Effectiveness of Biologics in Inflammatory Bowel Disease

background and aims: there is a need to evaluate the benefit-risk ratio of current therapies in inflammatory bowel disease (IBD) patients to provide the best quality of care. the primary objective of I-CARE (IBD cancer and serious infections in europe) was to assess prospectively safety concerns in IBD, with specific focus on the risk of cancer/lymphoma and serious infections in patients treated with anti-tumor necrosis factor and other biologic monotherapy as well as in combination with immunomodulators. methods: I-CARE was designed as a european prospective longitudinal observational multicenter cohort study to include patients with a diagnosis of crohn's disease, ulcerative colitis, or IBD unclassified established at least 3 months prior to enrollment. results: a total of 10,206 patients were enrolled between march 2016 and april 2019, including 6169 (60.4%) patients with crohn's disease, 3853 (37.8%) with ulcerative colitis, and 184 (1.8%) with a diagnosis of IBD unclassified. thirty-two percent of patients were receiving azathioprine/thiopurines, 4.6% 6-mercaptopurine, and 3.2% methotrexate at study entry. at inclusion, 47.3% of patients were treated with an anti-tumor necrosis factor agent, 8.8% with vedolizumab, and 3.4% with ustekinumab. roughly one-quarter of patients (26.8%) underwent prior IBD-related surgery. sixty-six percent of patients had been previously treated with systemic steroids. three percent of patients had a medical history of cancer prior to inclusion and 1.1% had a history of colonic, esophageal, or uterine cervix high-grade dysplasia. conclusions: I-CARE is an ongoing investigator-initiated observational european prospective cohort study that will provide unique information on the long-term benefits and risks of biological therapies in IBD patients. (eudra CT, Number: 2014-004728-23; clinical trials.gov, number: NCT02377258)