Modulation Of IL-17A And TL1A Largely Abrogates House Dust Mite-Induced Lung Inflammation In A Murine Model Of Allergic Airway Disease (54.5)

Recent studies suggest a role for Th17 responses in the increased airway neutrophilia associated with severe asthma. House dust mite (HDM) is a natural allergen to which asthmatics are often sensitized. Mice repeatedly challenged with HDM extract developed robust airway neutrophilia rapidly evolving into asthma-like disease with increased numbers of eosinophils and lymphocytes in bronchoalveolar lavages (BAL) as well as inflammatory infiltrates, vascular/muscular hypertrophy, interstitial fibrosis, epithelial hyperplasia and mucus accumulation in lung tissues. RNA and protein screening revealed a robust Th17 component post-HDM exposure. We thus evaluated whether IL-17A deficiency could modulate HDM-induced allergic airway disease. Airway neutrophilia was indeed abrogated in IL-17A deficient mice weekly challenged with HDM (acute model), however total BAL cellularity and lung mechanics remained comparable to those of HDM-challenged WT mice. In contrast, IL-17A deficient mice daily exposed to HDM (chronic model) had decreased BAL cellularity associated with reduced numbers of BAL macrophages, neutrophils, eosinophils and lymphocytes. Interestingly antibody neutralization of TL1A, a member of the TNF superfamily known to promote Th2 and Th17 responses, reduced BAL cellularity to baseline levels in HDM-challenged WT mice. Our results thus indicate that targeting Th17 responses can alleviate HDM-induced airway neutrophilia, and can also broadly modulate allergic airway disease.

Telomeric DNA induces apoptosis and senescence of human breast carcinoma cells

INTRODUCTION

Cancer is a leading cause of death in Americans. We have identified an inducible cancer avoidance mechanism in cells that reduces mutation rate, reduces and delays carcinogenesis after carcinogen exposure, and induces apoptosis and/or senescence of already transformed cells by simultaneously activating multiple overlapping and redundant DNA damage response pathways.

METHODS

The human breast carcinoma cell line MCF-7, the adriamycin-resistant MCF-7 (Adr/MCF-7) cell line, as well as normal human mammary epithelial (NME) cells were treated with DNA oligonucleotides homologous to the telomere 3' overhang (T-oligos). SCID mice received intravenous injections of MCF-7 cells followed by intravenous administration of T-oligos.

RESULTS

Acting through ataxia telangiectasia mutated (ATM) and its downstream effectors, T-oligos induced apoptosis and senescence of MCF-7 cells but not NME cells, in which these signaling pathways were induced to a far lesser extent. In MCF-7 cells, experimental telomere loop disruption caused identical responses, consistent with the hypothesis that T-oligos act by mimicking telomere overhang exposure. In vivo, T-oligos greatly prolonged survival of SCID mice following intravenous injection of human breast carcinoma cells.

CONCLUSION

By inducing DNA damage-like responses in MCF-7 cells, T-oligos provide insight into innate cancer avoidance mechanisms and may offer a novel approach to treatment of breast cancer and other malignancies.

Telomere-based DNA damage responses: a new approach to melanoma

Melanoma is the most fatal skin cancer, often highly resistant to chemotherapy. Here we show that treatment with an 11-base DNA oligonucleotide homologous to the telomere 3' overhang sequence (T-oligo) induces apoptosis of several established human melanoma cell lines, including the aggressive MM-AN line, whereas normal human melanocytes exposed to the same or higher T-oligo concentrations show only transient cell cycle arrest, implying that malignant cells are more sensitive to T-oligo effects. When MM-AN cells were briefly exposed to T-oligo in culture and injected into the flank or tail vein of SCID mice, eventual tumor volume and number of metastases were reduced 85-95% compared with control mice. Similarly, T-oligos administered intralesionally or systemically selectively inhibited the growth of previously established MM-AN tumor nodules in the flank and peritoneal cavity by 85 to 90% without detectable toxicity. We previously showed that T-oligos act through ATM, p95/Nbs1, E2F1, p16INK4A, p53, and the p53 homologue p73 to modulate downstream effectors and now additionally demonstrate striking down-regulation of the inhibitor of apoptosis protein livin/ML-IAP. We suggest that T-oligo mimics a physiologic DNA damage signal that is frequently masked in malignant cells and thereby activates innate cancer prevention responses. T-oligos may provide a novel therapeutic approach to melanoma.