Interleukin-1 receptor expression by ovine afferent lymph dendritic cells: response to secondary antigen challenge

Exacerbation of granuloma formation in IL-1 receptor antagonist-deficient mice with impaired dendritic cell maturation associated with Th2 cytokine production

Dendritic cell (DC) maturation at the site of inflammation and migration into draining lymph nodes is fundamental to initiate Ag-specific immune responses. Although several proinflammatory cytokines, including IL-1, are known to promote DC maturation in vitro, their contributions to DC activation and migration within peripheral inflamed tissue compartments are not yet fully understood. We show here that endogenous IL-1 receptor antagonist (IL-1ra) controls the activation state of liver-recruited DCs and their migration in a Propionibacterium acnes-induced murine granulomatous liver disease model. After P. acnes treatment, formation of portal tract-associated lymphoid tissue was conversely impaired in IL-1ra-deficient mice. IL-1ra-deficient mice developed hepatic granulomas within 3 days after P. acnes administration and showed a more pronounced granuloma formation than wild-type mice. Although sinusoidal granulomas contained numerous CD11c+ DCs at day 7, expressions of CCR7, IL-12p40 by these DCs were dramatically decreased in IL-1ra-deficient mice, suggesting aberrant DC maturation and sinusoid portal migration in the absence of endogenous IL-1ra. This was accompanied with enhanced intrahepatic Th2 cytokine production and severe hepatocellular damage. Thus, hepatocyte-derived IL-1ra may control optimal activation and migration of inflammatory DCs within the liver and thereby determine the local immune responses in granulomatous liver disease.

Vagal paraganglia bind biotinylated interleukin-1 receptor antagonist: a possible mechanism for immune-to-brain communication

Interleukin-1 beta is a proinflammatory cytokine released by activated immune cells. In addition to orchestrating immune responses to infection, interleukin-1 beta is a key mediator of immune-to-brain communication. Interleukin-1 beta and endotoxin (which releases IL1 beta from immune cells) cause centrally mediated illness responses such as fever, aphagia, etc. These effects are blocked by intraperitoneal IL1 receptor antagonist (IL1ra), suggesting critical involvement of peripheral IL1 receptors. Centrally mediated illness responses are also blocked by vagotomy, suggesting that IL1 beta directly or indirectly activates vagal afferents. To test for IL1 beta binding whole vagus (abdominal, laryngeal, and thoracic) and sections of hepatic vagus and liver hilus were incubated with biotinylated IL1ra and processed for avidin-biotin complex (ABC) or avidin-FITC histochemistry. Glomus cells of vagal paraganglia were labeled in all regions of the vagus. Biotinylated IL1ra also labeled smooth muscle and endothelial cells of blood vessels and lymphoid tissues. No label was present in omission or competition controls. These data suggest that centrally mediated illness responses result from IL1 activation of vagal paraganglia.

Flow cytometric analysis of cytokine receptors on human Langerhans' cells. Changes observed after short-term culture

It is well established that granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin (IL)-1 and tumour necrosis factor-alpha (TNF-alpha) are involved in Langerhans' cell (LC) development and dendritic cell traffic. However, little is known about the pattern of cytokine receptors on human LC and their modulation during different stages of maturation. The expression of cytokine receptors was studied by flow cytometry on both freshly isolated LC (fLC) and 72-hr cultured LC (cLC). Epidermal cell suspensions enriched in LC were obtained after skin trypsinization and Ficoll-Hypaque gradient. LC were identified by their CD1a positivity. Although the majority of fLC were positive for the alpha chain of GM-CSF receptor (GM-CSFR), the beta chain of GM-CSFR was detected only on 15% of CD1a+ cells. fLC were also positive for IL-1 receptor (IL-1R) type 1, IL-1R type 2, 75,000 molecular weight TNF receptor (TNFR) and interferon-gamma receptor (IFN-gamma R). IL-6R and its transducing signal gp130 were present in a subset of fLC. Granulocyte colony-stimulating factor receptor (G-CSFR), macrophage colony-stimulating factor receptor (M-CSFR), the alpha and beta chain of IL-2R, IL-4R, IL-7R, IL-8R and 55,000 molecular weight TNFR were not detected on fLC. After culture, LC up-regulated the expression of both the alpha and beta chains of GM-CSFR, IL-1R type 2, alpha and beta chains of IL-2R, IL-6R and gp130. In contrast, IL-1R type 1 and 75,000 molecular weight TNFR were down-modulated and the expression of IFN-gamma R was not affected by culture. These results suggest that LC undergo changes in the cytokine receptor repertory during in vitro maturation.