Per a 10 protease activity modulates CD40 expression on dendritic cell surface by nuclear factor-kappaB pathway

Area of Science:

• Immunology
• Allergology
• Protease biochemistry

Background:

• Per a 10, a serine protease from Periplaneta americana, is implicated in allergic responses.
• The precise mechanisms by which Per a 10 modulates dendritic cell (DC) function remain incompletely understood.
• Understanding Per a 10's effects on DC signaling is crucial for developing targeted allergy therapies.

Purpose of the Study:

• To investigate the impact of Per a 10 serine protease activity on CD40 expression and downstream signaling in human monocyte-derived DCs.
• To elucidate the role of nuclear factor-kappa B (NF-κB) and p38 mitogen-activated protein kinase (MAPK) pathways in Per a 10-mediated DC modulation.
• To assess the consequences of Per a 10-induced DC dysfunction on T cell responses.

Main Methods:

• Monocyte-derived DCs from cockroach-allergic patients were treated with active or heat-inactivated Per a 10.
• Flow cytometry was used to analyze cell surface and soluble CD40 expression.
• Cytokine levels (IL-12, IFN-γ, IL-6, TNF-α, IL-4) were measured using ELISAs.
• NF-κB activation and p38 MAPK phosphorylation were assessed.
• Inhibition studies using pathway-specific inhibitors were performed.

Main Results:

• Active Per a 10 significantly reduced DC surface CD40 expression while increasing soluble CD40, suggesting CD40 cleavage.
• Per a 10 activity decreased IL-12 and IFN-γ secretion by DCs, correlating with reduced CD40 expression.
• Active Per a 10 stimulation led to lower NF-κB activation in DCs.
• Inhibition of NF-κB suppressed CD40 expression and IL-12 secretion, confirming NF-κB's requirement for CD40 upregulation.
• p38 MAPK activation by Per a 10 did not affect CD40 expression but was involved in cytokine secretion.
• Inhibition of p38 MAPK or NF-κB pathways suppressed multiple DC-derived cytokines (IL-12, IFN-γ, IL-6, TNF-α).
• DCs treated with active Per a 10 showed reduced capacity to stimulate CD4+ T cells, resulting in lower secretion of IL-4, IL-6, IL-12, and TNF-α.

Conclusions:

• The serine protease activity of Per a 10 down-regulates CD40 expression on dendritic cells.
• CD40 down-regulation by Per a 10 is linked to reduced NF-κB activation, thereby modulating DC-mediated immune responses.
• Per a 10 impairs DC function, affecting their ability to stimulate T cells and potentially contributing to allergic inflammation.