DGKα DNA vaccine relieves airway allergic inflammation in asthma model possibly via induction of T cell anergy

Abstract

Induction of T cell immune tolerance is thought to be a good method for treatment of asthma. Diacylglycerol kinases alpha (DGKα), enzymes that catalyze phosphorylation of diacylglycerol to produce phosphatidic acid, could inhibit diacylglycerol (DAG)-mediated signaling following T-cell receptor engagement and prevent T cell hyperactivation, thus playing important roles in the induction of T cell anergy. In the present study, we aimed to investigate the effects of DNA vaccine encoding DGKα gene administration on allergen-induced airway allergic inflammation in the murine model of asthma. Animal models were created and plasmid containing DGKα were constructed. Cytokine production was detected after the administration of DGKα gene plasmid. Immunization of mice with alum-adsorbed ovalbumin (OVA) followed by challenged with inhalation of aerosolized OVA resulted in the development of airway allergic inflammation. Administration of DGKα gene before the aerosolized OVA challenge significantly decreased the allergic airway inflammation and eosinophil infiltration in bronchoalveolar lavage fluid (BALF). Immunization with DGKα DNA vaccine decreased OVA-specific IgE and interleukin 13 (IL-13) levels in sera, and increased the IFN-γ level in BALF. The results of the present study provide evidence for the potential utility of the administration of DGKα DNA vaccine as an approach to gene therapy for asthma.

Keywords: Asthma; DNA vaccine; airway inflammation; diacylglycerol kinases alpha.

Figure 1

Experimental design Animals were randomly divided into 4 groups. All the animals except for the normal group were sensitized and challenged with OVA, while mice in the normal group received normal saline. Plasmid DNA of DGKα or control plasmid was intramuscularly injected twice on day -13, -4.

Figure 2

The expression of DGKα protein in spleen and lung. Mouse tissues were prepared and proteins were assessed by SDS-PAGE and western blotting. The blot was probed with anti-DGKα Ab. 1. Normal group, 2. Model group, 3. DGKα plasmid group, 4. Control plasmid group.

Figure 3

Immunization with DGKα DNA could prevent airway eosinophilic inflammation. Lung tissues and BALF were collected 48 hours after the last OVA challenge. A. Representative histological examination of lung section stained with hematoxylin and eosin (×400 magnification). a. Normal group, b. Model group, c. DGKα plasmid group, d. Control plasmid group; B. Total cell numbers in BALF were assessed. C. Differential cell counts in BALF were analyzed. Results are expressed as mean±SD pg/ml for eight mice in each group. Results are expressed as mean±SD pg/ml for eight mice in each group (*p<0.05).

Figure 4

Immunization with DGKα DNA decreased the level of IL-5 and IL-13, and increased the level of IFN-γ in BALF. Results are expressed as mean±SD pg/ml for eight mice in each group (*p<0.05).

Figure 5

Immunization with DGKα DNA decreased the level of serum OVA-specific IgE. Results are expressed as mean±SD pg/ml for twelve mice in each group (*p<0.05).