Cutaneous Antigen Priming via Gene Gun Leads to Skin-Selective Th2 Immune-Inflammatory Responses

Abstract

It is becoming increasingly evident that the compartmentalization of immune responses is governed, in part, by tissue-selective homing instructions imprinted during T cell differentiation. In the context of allergic diseases, the fact that “disease” primarily manifests in particular tissue sites, despite pervasive allergen exposure, supports this notion. However, whether the original site of Ag exposure distinctly privileges memory Th2 immune-inflammatory responses to the same site, while sparing remote tissue compartments, remains to be fully investigated. We examined whether skin-targeted delivery of plasmid DNA encoding OVA via gene-gun technology in mice could generate allergic sensitization and give rise to Th2 effector responses in the skin as well as in the lung upon subsequent Ag encounter. Our data show that cutaneous Ag priming induced OVA-specific serum IgE and IgG1, robust Th2-cytokine production, and late-phase cutaneous responses and systemic anaphylactic shock upon skin and systemic Ag recall, respectively. However, repeated respiratory exposure to aerosolized OVA failed to instigate airway inflammatory responses in cutaneous Ag-primed mice, but not in mice initially sensitized to OVA via the respiratory mucosa. Importantly, these contrasting airway memory responses correlated with the occurrence of Th2 differentiation events at anatomically separate sites: indeed cutaneous Ag priming resulted in Ag-specific proliferative responses and Th2 differentiation in skin-, but not thoracic-, draining lymph nodes. These data indicate that Ag exposure to the skin leads to Th2 differentiation within skin-draining lymph nodes and subsequent Th2 immunity that is selectively manifested in the skin.

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“…37 However, i.m. DNA injection resulted in Th1-biased immune responses, 38 which favor antitumor immunity.…”

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“…injection of 8 g of OVA (Sigma-Aldrich) and 4 mg of aluminum hydroxide (Sigma-Aldrich) in a total volume of 0.5 ml of sterile PBS. Sensitization to OVA via the skin was achieved by way of particle bombardment of plasmid OVA-coated gold particles via the Helios gene gun (GG) (Bio-Rad) (41). We have reported previously that delivery of plasmids expressing OVA, but not luciferase cDNA or empty control plasmids, nor delivery of gold particles alone, leads to OVA-specific Th2 immunity (41).…”

“…injection with 10 g of OVA in 10 l of sterile PBS into one ear, and vehicle (sterile PBS) into the opposite ear, 1 wk postcutaneous Th2 sensitization (41). Ear thickness was measured before and at several time points after injection using a modified low-tension thickness gauge (Dyer).…”

“…Sensitization to OVA via the skin was achieved by way of particle bombardment of plasmid OVA-coated gold particles via the Helios gene gun (GG) (Bio-Rad) (41). We have reported previously that delivery of plasmids expressing OVA, but not luciferase cDNA or empty control plasmids, nor delivery of gold particles alone, leads to OVA-specific Th2 immunity (41). Briefly, each animal received three nonoverlapping deliveries of gold particles coated with OVAexpressing plasmids, totaling 1 g of plasmid per inoculation (i.e., 0.33 g of DNA per delivery), onto the ventral abdominal skin on three occasions at weekly intervals.…”

“…The plasmid used for these studies was a modified version of pcDNA3.1 ϩ (Invitrogen Life Technologies) containing the cDNA for OVA under control of the human CMV intermediate-early promoter. Preparation of DNA-coated gold particles was performed, as previously described (41).…”