title: Per a 10 protease activity modulates CD40 expression on dendritic cell surface by nuclear factor-kappaB pathway.
abstract: Serine protease activity of Per a 10 from Periplaneta americana modulates dendritic cell (DC) functions by a mechanism(s) that remains unclear. In the present study, Per a 10 protease activity on CD40 expression and downstream signalling was evaluated in DCs. Monocyte-derived DCs from cockroach-allergic patients were treated with proteolytically active/heat-inactivated Per a 10. Stimulation with active Per a 10 demonstrated low CD40 expression on DCs surface (P < 0·05), while enhanced soluble CD40 level in the culture supernatant (P < 0·05) compared to the heat-inactivated Per a 10, suggesting cleavage of CD40. Per a 10 activity reduced the interleukin (IL)-12 and interferon (IFN)-γ secretion by DCs (P < 0·05) compared to heat-inactivated Per a 10, indicating that low CD40 expression is associated with low levels of IL-12 secretion. Active Per a 10 stimulation caused low nuclear factor-kappa B (NF-κB) activation in DCs compared to heat-inactivated Per a 10. Inhibition of the NF-κB pathway suppressed the CD40 expression and IL-12 secretion by DCs, further indicating that NF-κB is required for CD40 up-regulation. CD40 expression activated the tumour necrosis factor (TNF) receptor-associated factor 6 (TRAF6), thereby suggesting its involvement in NF-κB activation. Protease activity of Per a 10 induced p38 mitogen-activated protein kinase (MAPK) activation that showed no significant effect on CD40 expression by DCs. However, inhibiting p38 MAPK or NF-κB suppressed the secretion of IL-12, IFN-γ, IL-6 and TNF-α by DCs. Such DCs further reduced the secretion of IL-4, IL-6, IL-12 and TNF-α by CD4(+) T cells. In conclusion, protease activity of Per a 10 reduces CD40 expression on DCs. CD40 down-regulation leads to low NF-κB levels, thereby modulating DC-mediated immune responses.
authors.affiliation: Allergy and Immunology Section, CSIR-Institute of Genomics and Integrative Biology, Delhi, India; Academy of Scientific and Innovative Research (AcSIR), CSIR, New Delhi, India.
authors.forename: C
authors.initials: C
authors.lastname: Goel
authors.forename: N
authors.initials: N
authors.lastname: Kalra
authors.forename: B S
authors.initials: BS
authors.lastname: Dwarakanath
authors.forename: S N
authors.initials: SN
authors.lastname: Gaur
authors.forename: N
authors.initials: N
authors.lastname: Arora
mesh_terms: D000328:Adult; D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D019013:CD40 Antigens / Q000276:immunology*; D016207:Cytokines / Q000276:immunology; D003713:Dendritic Cells / Q000276:immunology* / Q000473:pathology; D005260:Female; D006801:Humans; D019476:Insect Proteins / Q000276:immunology*; D008297:Male; D016328:NF-kappa B / Q000276:immunology*; D010447:Peptide Hydrolases / Q000276:immunology*; D010526:Periplaneta / Q000276:immunology*; D015398:Signal Transduction / Q000276:immunology; D048029:TNF Receptor-Associated Factor 6 / Q000276:immunology; D015854:Up-Regulation / Q000276:immunology*
chemical_list: D019013:CD40 Antigens; D016207:Cytokines; D019476:Insect Proteins; D016328:NF-kappa B; D048029:TNF Receptor-Associated Factor 6; D010447:Peptide Hydrolases
keywords: CD40; Per a 10; allergen; dendritic cell; proteolytic activity