Self-antigen MASH2 combined with the AS15 immunostimulant induces tumor protection in colorectal cancer mouse models.

Human achaete scute homolog 2 (HASH2) and its murine ortholog MASH2 are potential targets for colorectal cancer immunotherapy. We assessed immunogenicity and antitumor potential of recombinant MASH2 protein combined with AS15 immunostimulant (recMASH2+AS15) in CB6F1 and Apc+/Min-FCCC mice. CB6F1 mice received 4 injections of recMASH2+AS15 or AS15 alone before challenge with TC1-MASH2 tumor cells (Tumor Challenge). Apc+/Min-FCCC mice received 9 injections of recMASH2+AS15 or vehicle (phosphate buffer saline [PBS] or AS15 alone), before (two independent Prophylactic Studies) or after (Immunotherapy) colon adenomas were detectable by colonoscopy. CB6F1 mice immunized with recMASH2+AS15 had a significantly smaller mean tumor size and improved survival rate compared to controls (104 mm2 vs. 197 mm2 [p = 0.009] and 67% vs. 7% [p = 0.001], respectively). In Prophylactic Study 1, the mean number of colon adenomas was significantly lower in Apc+/Min-FCCC mice receiving recMASH2+AS15 compared to PBS (1.8 [95% confidence interval 1.0-3.3] vs. 5.2 [3.7-7.4], p = 0.003). Fewer microadenomas were observed in recMASH2+AS15 groups compared to PBS in both Prophylactic Studies (Study 1: mean 0.4 [0.2-1.0] vs. 1.5 [0.9-2.4], p = 0.009; Study 2: 0.4 [0.2-0.6] vs. 1.1 [0.8-1.5], p = 0.001). In the Immunotherapy Study, fewer colon adenomas tended to be observed in recMASH2+AS15-treated mice (4.1 [2.9-6.0]) compared to controls (AS15 4.7 [3.3-6.6]; PBS 4.9 [3.5-6.9]; no significant difference). recMASH2+AS15 induced MASH2-specific antibody and CD4+ responses in both mouse models. recMASH2+AS15 partially protected mice against MASH2-expressing tumors and reduced spontaneous colorectal adenomas in Apc+/Min-FCCC mice, indicating that MASH2/HASH2 antigens are targets for colorectal cancer immunotherapy.

The role of gamma delta T cells in airway epithelial injury and bronchial responsiveness after chlorine gas exposure in mice.

BACKGROUND: Acute exposure to chlorine (Cl2) gas causes epithelial injury and airway dysfunction. gammadelta T cells are present in the mucosal surface of the airways and may contribute to the injury/repair response of the epithelium. METHODS: C57Bl/6J (wild type) and TCR-delta-/- mice exposed to Cl2 (400 ppm) for 5 minutes underwent measurements of airway responses to i.v. methacholine (MCh) at 1, 3, and 5 days after exposure. Bronchoalveolar lavage was performed to determine epithelial and leukocyte counts, and protein content. Tissue repair was assessed by proliferating cell nuclear antigen (PCNA) immunoreactivity and by expression of keratinocyte growth factor (KGF) mRNA by real-time PCR. RESULTS: Wild type mice developed a greater degree of airway hyperresponsiveness to MCh at 1 day post exposure to Cl2 compared with TCR-delta-/- mice. Epithelial cell counts in BAL after Cl2 exposure were greater in TCR-delta-/- mice, but macrophages showed a later peak and granulocyte numbers were lower in TCR-delta-/- than in wild type mice. Both groups had increased levels of total protein content in BAL after Cl2 exposure that resolved after 3 and 5 days, respectively. Epithelial proliferating cell nuclear antigen staining was increased at 1 and 3 days post exposure and was similar in the two groups. KGF mRNA was constitutively expressed in both groups and did not increase significantly after Cl2 but expression was lower in TCR-delta-/- mice. CONCLUSION: The severity of airway epithelial injury after Cl2 is greater in TCR-delta-/- mice but the inflammatory response and the change in airway responsiveness to methacholine are reduced. The rates of epithelial regeneration are comparable in both groups.