Cytokine expression and antigen-presenting capacity of 4F7+ dendritic cells derived from dermis, spleen, and lymph nodes

Serum biomarkers in a mouse model of bacterial-induced inflammatory bowel disease

BACKGROUND

The diagnosis and classification of inflammatory bowel disease (IBD) require both clinical and histopathologic data. Serum biomarkers would be of considerable benefit to noninvasively monitor the progression of disease, assess effectiveness of therapies, and assist in understanding disease pathogenesis. Currently, there are limited noninvasive biomarkers for monitoring disease progression in animal IBD models, which are used extensively to develop new therapies and to understand IBD pathogenesis.

METHODS

Serum biomarkers of early and late IBD were identified using multianalyte profiling in mdr1a(-/-) mice with IBD triggered by infection with Helicobacter bilis. The correlation of changes in these biomarkers with histopathology scores and clinical signs in the presence and in the absence of antibiotic treatment was determined.

RESULTS

Serum levels of interleukin (IL)-11, IL-17, 10-kDa interferon-gamma-inducible protein (IP-10), lymphotactin, monocyte chemoattractant protein (MCP)-1, and vascular cell adhesion molecule (VCAM)-1 were elevated early in IBD. In late, more severe IBD, serum levels of IL-11, IP-10, haptoglobin, matrix metalloproteinase-9, macrophage inflammatory protein (MIP)-1gamma, fibrinogen, immunoglobulin A, MIP-3 beta (beta), VCAM-1, apolipoprotein (Apo) A1, and IL-18 were elevated. All late serum biomarkers except Apo A1 correlated with histopathology scores. Antibiotic treatment improved clinical signs of IBD and decreased mean serum values of many of the biomarkers. For all biomarkers, the individual pathology scores correlated significantly with individual serum analyte levels after treatment.

CONCLUSIONS

Serum analyte measurement is a useful, noninvasive method for monitoring disease in a mouse model of bacterial-induced IBD.

Functional caspase-1 is required for Langerhans cell migration and optimal contact sensitization in mice

Langerhans cell (LC) migration from epidermis to draining lymph node is a critical first step in cutaneous immune responses. Both TNF-alpha and IL-1 beta are important signals governing this process, but the potential regulatory role of IL-1 alpha processing by caspase-1 is unknown. In wild-type (WT) mice, application of the contact allergens 2,4-dinitrofluorobenzine and oxazolone lead to a marked reduction in epidermal LC numbers, but in caspase-1-deficient mice this reduction was not observed. Moreover, although intradermal injection of TNF-alpha (50 ng) induced epidermal LC migration in WT mice, this cytokine failed to induce LC migration in caspase-1-deficient mice. Intradermal IL-1 beta (50 ng) caused a similar reduction in epidermal LC numbers in both WT and caspase-1-deficient mice, indicating that, given an appropriate signal, caspase-1-deficient epidermal LC are capable of migration. Contact hypersensitivity to both 2,4-dinitrofluorobenzine and oxazolone was inhibited in caspase-1-deficient mice, indicating a functional consequence of the LC migration defect. In organ culture the caspase-1 inhibitor Ac-YVAD-cmk, but not control peptide, potently inhibited the epidermal LC migration that occurs in this system, and reduced spontaneous migration of LC was observed in skin derived from caspase-1-deficient mice. Moreover, Ac-YVAD-cmk applied to BALB/c mouse skin before application of contact sensitizers inhibited LC migration and contact hypersensitivity in vivo. Taken together, these data indicate that caspase-1 may play a central role in the regulation of LC migration and suggest that the activity of this enzyme is amenable to control by specific inhibitors both in vivo and in vitro.