Search

Currently, more antimicrobial drug candidates are urgently needed to combat the rise in drug-resistance among pathogenic microbes. A new antimicrobial peptide, MP1102, a variant of NZ2114, was designed, evaluated, and overexpressed in Pichia pastoris. The total secreted protein in cultures reached 695 mg/l, and the concentration of the recombinant MP1102 (rMP1102) was 292 mg/l. rMP1102 was purified from the fermentation supernatant by one-step cation exchange chromatography to obtain a yield of 197.1 mg/l with 96.4 % purity. rMP1102 exhibited potent activity against Gram-positive bacteria, and its minimum inhibitory concentrations (MICs) for four Staphyloccocus aureus ( S. aureus) strains ranged from 0.028 to 0.11 μM, and it had stronger activity (MIC = 0.04 to 0.23 μM) to 20 clinical isolates of MRSA (cMRSA) than rNZ2114 (MIC = 0.11 to 0.90 μM). rMP1102 was shown to kill over 99.9 % of tested S. aureus cells within 6 h when treated at one, two, and four times its MIC and over 90 % of S. aureus cells within 12 h at concentrations of 5, 10, and 20 mg/kg in a mouse thigh infection model. The higher sensitivity of MRSA to MP1102 than to its parental peptide, NZ2114, indicated by this initial pharmacodynamic analysis suggests a possible difference in the killing mechanism of these two molecules. rMP1102 caused less than 0.05 % hemolytic activity at 128 μg/ml and exhibited good thermostability from 20 to 80 °C, with its highest activity being observed at pH 8.0. These results suggest that this yeast expression system is feasible for large-scale production, and rMP1102 exerted stronger activity against S. aureus than NZ2114 via a different mechanism and exhibited potential as a new antimicrobial agent for S. aureus, especially MRSA infections. [ABSTRACT FROM AUTHOR]

The programmed death-1 (PD-1) molecule is mainly expressed on functionally 'exhausted' CD8 T cells, dampening the host antitumor immune response. We evaluated the ratio between effective and regulatory T cells (Tregs) and PD-1 expression as a prognostic factor for operable breast cancer patients. A series of 218 newly diagnosed invasive breast cancer patients who had undergone primary surgery at Ruijin Hospital were identified. The influence of CD8 cytotoxic T lymphocytes, FOXP3 (Treg cell marker), and PD-1 immune cell counts on prognosis was analyzed utilizing immunohistochemistry. Both PD-1 immune cells and FOXP3 Tregs counts were significantly associated with unfavorable prognostic factors. In bivariate, but not multivariate analysis, high tumor infiltrating PD-1 cell counts correlated with significantly shorter patient survival. Our results suggest a prognostic value of the PD-1 immune cell population in such breast cancer patients. Targeting the PD-1 pathway may be a feasible approach to treating patients with breast cancer. [ABSTRACT FROM AUTHOR]