Bacterial outer membrane vesicles engineered with lipidated antigens as a platform for Staphylococcus aureus vaccine.

Bacterial outer membrane vesicles (OMVs) represent an interesting vaccine platform for their built-in adjuvanticity and simplicity of production process. Moreover, OMVs can be decorated with foreign antigens using different synthetic biology approaches. However, the optimal OMV engineering strategy, which should guarantee the OMV compartmentalization of most heterologous antigens in quantities high enough to elicit protective immune responses, remains to be validated. In this work we exploited the lipoprotein transport pathway to engineer OMVs with foreign proteins. Using 5 Staphylococcus aureus protective antigens expressed in Escherichia coli as fusions to a lipoprotein leader sequence, we demonstrated that all 5 antigens accumulated in the vesicular compartment at a concentration ranging from 5 to 20% of total OMV proteins, suggesting that antigen lipidation could be a universal approach for OMV manipulation. Engineered OMVs elicited high, saturating antigen-specific antibody titers when administered to mice in quantities as low as 0.2 µg/dose. Moreover, the expression of lipidated antigens in E. coli BL21(DE3)ΔompAΔmsbBΔpagP was shown to affect the lipopolysaccharide structure, with the result that the TLR4 agonist activity of OMVs was markedly reduced. These results, together with the potent protective activity of engineered OMVs observed in mice challenged with S. aureus Newman strain, makes the 5-combo-OMVs a promising vaccine candidate to be tested in clinics.

Locally advanced rectal cancer patients receiving radio-chemotherapy: a novel clinical-pathologic score correlates with global outcome.

PURPOSE: To determine the importance of downstaging of locally advanced rectal cancer after neoadjuvant treatment. METHODS AND MATERIALS: The study included all consecutive patients with locally advanced rectal cancer who underwent neoadjuvant treatment (chemotherapy and/or radiotherapy) in different Italian centers from June 1996 to December 2003. A novel score was used, calculated as the sum of numbers obtained by giving a negative or positive point, respectively, to each degree of increase or decrease in clinical to pathologic T and N status. RESULTS: A total of 317 patients were eligible for analysis. Neoadjuvant treatments performed were as follows: radiotherapy alone in 75 of 317 patients (23.7%), radiotherapy plus chemotherapy in 242 of 317 patients (76.3%). Worse disease-free survival was observed in patients with a lower score (Score 1 = -3 to +3 vs. Score 2 = +4 to +7; p = 0.04). CONCLUSIONS: Our results suggest that a novel score, calculated from preoperative and pathologic tumor and lymph node status, could represent an important parameter to predict outcome in patients receiving neoadjuvant treatment for rectal cancer. The score could be useful to select patients for adjuvant chemotherapy after neoadjuvant treatment and surgery.