Protease activity of Per a 10 potentiates Th2 polarization by increasing IL‐23 and OX40L

Abstract

Proteases are implicated in exacerbation of allergic diseases. In this study, the role of proteolytic activity of Per a 10 was evaluated on Th2 polarization. Intranasal administration of Per a 10 in mice led to allergic airway inflammation as seen by higher IgE levels, cellular infiltration, IL-17A, and Th2 cytokines, whereas, inactive ( )Per a 10 showed attenuated response. There was an increased OX40L expression on lung and lymph node dendritic cells in Per a 10 immunized group and on Per a 10 stimulated BMDCs. Reduction in CD40 expression without any change at transcript level in lungs of Per a 10 immunized mice suggested CD40 cleavage. BMDCs pulsed with Per a 10 showed reduced CD40 expression with lower IL-12p70 secretion as compared to heat inactivated Per a 10. IL-23, TNF-α, and IL-6 levels were significantly higher in Per a 10 stimulated BMDCs supernatant. In DC-T cell coculture studies, Per a 10 pulsed BMDCs showed higher levels of IL-4 and IL-13 that were reduced on blocking of either IL-23 or OX40L. In conclusion, the data suggests a critical role of protease activity of Per a 10 in promoting Th2 polarization by increasing IL-23 secretion and OX40L expression on dendritic cells.Keywords: CD40 r Cytokines r Dendritic cell r OX40L r Protease allergen Additional supporting information may be found in the online version of this article at the publisher's web-site IntroductionProteases are known to play an important role in manifestation of diseases like cancer, coagulopathies, respiratory inflammatory diseases, rheumatoid arthritis, and degenerative diseases [1][2][3]. Proteases from sources like house dust mite (Der p 1, Der p 3, Der p 6, Der p 9, Der f 1) and fungi (Asp f 13, Pen c 1, Pen c 13, Epi p 1) have been characterized as potent allergens [4]. Protease allergens act by proteolytic cleavage of an array of cell surface molecules and are known to modulate the functions of a variety of cell types including both immune and structural cells [5]. Proteolytic allergens from house dust mite are known to exacerbate allergic immune responses by selective cleavage of CD23, CD25, DC-SIGN, and DC-SIGNR on surface of immune cells Correspondence: Dr. Naveen Arora e-mail: naveen@igib.res.in; navdelhi@hotmail.com [6,7]. Further, cleavage and subsequent activation of PAR receptors by proteases lead to increased secretion of chemokines, proinflammatory, and pro Th2 cytokines from airway epithelial cells [8,9]. Studies have reported impaired epithelial barrier function as the feature of allergic diseases like asthma and atopic dermatitis [10]. The enzymatic activity of proteases has been reported to compromise epithelial barrier directly by cleaving tight junction proteins ZO-1 and occludin thereby increasing epithelial permeability [11,12]. Proteases can also act as adjuvants to bystander allergens present in the same microenvironment [13,14].Cockroaches have emerged as an important source of indoor allergens worldwide and cockroach extract is shown to be rich in proteases [15]. Previously, Per a 10, a serine protea...

Serine protease allergen favours Th2 responses via PAR‐2 and STAT3 activation in murine model

“…Previously, we have shown that Per a 10, a major serine protease allergen from Periplaneta americana , activates DCs to secrete higher levels of IL‐23 and a lower level of IL‐12p70. A downregulation of IL‐12p35 and an upregulation of IL‐23p19 levels were observed in mouse lungs upon intranasal administration of Per a 10 and blocking of IL‐23 led to a reduction in the levels of Th2 cytokines in DC‐T‐cell coculture studies . However, the mechanisms which differentially regulate the secretion of cytokines by dendritic cells upon activation by protease allergens are not understood.…”

“…Proteolytically active Per a 10 leads to a downregulation of IL‐12p35 and an upregulation of IL‐23p19 at transcript level. Inactivation of protease activity attenuates allergic immune responses . In the present study, we have elucidated the mechanism by which protease activity of Per a 10 activates dendritic cells to create a cytokine milieu rich in IL‐23 and deficient in IL‐12p70 and leads to Th2 polarization.…”

“…Per a 10‐induced mouse model of allergic airway inflammation was generated as described elsewhere . PAR‐2 activation was blocked by intranasal administration of 10 ng of SAM11 or isotype control (mouse IgG2a), 30 minute prior to Per a 10 administration on days 0, 2 and 4.…”

“…BMDCs were generated from femur and tibia of BALB/c mice using the protocol previously described . PAR‐2 activation was blocked by treating cells with SAM11 or isotype control for 2.5 hour and stimulated with Per a 10, whereas cells stimulated with media served as control.…”

“…Proteases act via cleavage of tight junction proteins such as ZO‐1 and occludin increasing epithelial permeability, and a number of cell surface receptors such as CD25, CD23 and DC‐SIGN influencing the functions of a wide array of cells . Protease allergens activate dendritic cells and lead to upregulation of CD86 and cleavage of CD40 to favour Th2 responses . Furthermore, proteases can also act as adjuvants for other proteins present in the same microenvironment .…”