In the context of food allergy

In the context of food allergy it is hypothesized that intestinal barrier dysfunction might contribute to both antigen sensitization and the IgE/mast cell mediated effector phase of allergic disease, however no concluding data has been published to date [5]. An understanding of the mechanism of primary sensitization to Ezetimibe is paramount for determining the pathogenesis of allergic diseases and for their eventual prevention [6]. Several studies have shown that inhalant allergens which posses proteolytic activity can disrupt the airway epithelial barrier and skin barrier by direct activity against TJ occludin [7], [8], [9], [10], [11]. It has been recently shown that papain, a cysteine protease from papaya, can cause epidermal barrier impairment in human primary keratinocytes and thereby, like house dust mite allergen Der p 1 [7], might facilitate the sensitization to secondary allergens [12]. Actinidin (Act d 1) belongs to the papain-like family of cysteine proteases and is a major allergen from kiwifruit, where it constitutes up to 50% of soluble proteins [13], [14], [15]. Interestingly, active Act d 1 retains its primary structure, proteolytic activity, and immunological reactivity under conditions of simulated gastric followed by simulated intestinal digestion [16], thus indicating that it is probably capable of reaching the intestinal mucosa in a proteolytically active and immunogenic state. Furthermore, in a set of recent in vitro studies it was demonstrated that Act d 1 induces changes in the morphology and adhesion of T84 human colonic crypt epithelial cell monolayers [17], and breaches the occludin network [18]. Therefore, we hypothesize that the proteolytic activity of Act d 1 disrupts the integrity of tight junction protein occludin and enables passage of this kiwifruit allergen through the intestinal barrier. Our specific aims were: (i) to evaluate the impact of proteolytic activity of Act d 1 in vitro by measuring parameters of permeability in human adenocarcinoma enterocyte-like Caco-2 cell monolayers, (ii) to delineate specific human occludin degradation and map out the putative cleavage sites, and (iii) to demonstrate in vivo in a mouse model that Act d 1 is capable of increasing permeability of the intestinal barrier. The answer to these questions will provide a platform for future studies on the mechanism of food allergy sensitization, a yet unresolved fundamental aspect of food allergy pathogenesis.
Materials and methods
Results and discussion
Conclusions In this study, we show for the first time that a plant-derived food cysteine protease Act d 1 increases intestinal permeability in both in vivo (mice) and in vitro (Caco-2 cell culture) models. We further provide mechanistic evidence of increased permeability by demonstrating proteolytical degradation of human occludin, a key epithelial tight junction transmembrane protein. These findings indicate that food allergens with intrinsic proteolytic activity can compromise the gut epithelial barrier, contributing to the sensitization process in food allergy pathogenesis.
Transparency document
Acknowledgments This research was supported by Ministry of Education, Science and Technological Development of the Republic of Serbia, grant No. 172049. The authors acknowledge support of the FP7 RegPot project FCUB ERA GA No. 256716. The EC does not share responsibility for the content of the article MGJ, AN and JJS are members of COST Action FA1402 ImpARAS.
Introduction Filarial parasites are responsible each year for millions of human infections worldwide, causing chronic diseases that include lymphatic filariasis (elephantiasis) due to Brugia malayi or Wuchereria bancrofti infection, and onchocerciasis (river blindness) as a result of infection by Onchocerca volvulus (Lustigman et al., 2012). Present international control programs are focused on the reduction of transmission with the ultimate goal of eliminating these diseases. They are, however, almost universally based on a single strategy: the mass administration of microfilaricidal drugs (Molyneux and Taylor, 2001, Molyneux et al., 2003, Chu et al., 2010, Taylor et al., 2010, Hoerauf et al., 2011). Importantly, treatment of filarial infections in humans is still suboptimal due to a lack of macrofilaricidal drugs (i.e. drugs that can kill adult worms), and no vaccines are yet available to prevent new infections (Hoerauf et al., 2011, Lustigman et al., 2012, Prichard et al., 2012). Additional research is critically needed to discover novel drug targets and to develop a new generation of drugs with macrofilaricidal effects.