Interaction of the antimicrobial peptides caerin 1.1 and aurein 1.2 with intact bacteria by H-2 solid-state NMR

Nuclear magnetic resonance (NMR) is commonly used to probe the effect of antimicrobial agents on bacterial membranes using model membrane systems. Ideally, considering the complexity of membranes, the interaction of molecules with membranes should be studied in vivo. The interactions of two antimicrobial peptides (AMPs) with intact Escherichia coli and Bacillus subtilis were investigated using deuterium solid-state NMR. Specifically, we studied caerin 1.1 and aurein 1.2 isolated from the skin of Australian tree frogs. The minimal inhibitory concentration value for E. coli and B. subtilis was about 100μg/mL and 30μg/mL, respectively, for both peptides. A protocol to deuterate the membrane phospholipids of non-mutated B. subtilis was established using deuterated palmitic acid. 2H NMR spectra combined with spectral moment analysis support the interaction of the two AMPs with the hydrophobic core of the bacterial membranes. The presence of peptides decreased the order of the lipid acyl chains for both E. coli and B. subtilis, but at higher peptide concentrations for the Gram(+) bacteria. This may be explained by the presence of other cell wall components, such as the negatively-charged teichoic and lipoteichoic acids in the peptidoglycan, which would interact with the AMPs and decrease their actual concentration on the membrane surface. The mechanism of action of the AMPs thus depends on their local concentration as well as the membrane environment. The differences between the AMPs interaction with E. coli and B. subtilis reveal the importance of studying intact bacteria

Lenalidomide in combination with intravenous rituximab (revri) in relapsed/refractory primary cns lymphoma or primary intraocular lymphoma: a multicenter prospective "

International audiencePrimary central nervous system lymphomas (PCNSLs) are mainly diffuse large B-cell lymphomas (DLBCLs) of the non-germinal center B-cell (non-GCB) subtype. This study aimed to determine the efficacy of rituximab plus lenalidomide (R2) in DLBCL-PCNSL.Patients with refractory/relapsed (R/R) DLBCL-PCNSL or primary vitreoretinal lymphoma (PVRL) were included in this prospective phase II study. The induction treatment consisted of eight 28-day cycles of R2 (rituximab 375/m2 i.v. D1; lenalidomide 20 mg/day, D1-21 for cycle 1; and 25 mg/day, D1-21 for the subsequent cycles); in responding patients, the induction treatment was followed by a maintenance phase comprising 12 28-day cycles of lenalidomide alone (10 mg/day, D1-21). The primary end point was the overall response rate (ORR) at the end of induction (P0 = 10%; P1 = 30%).Fifty patients were included. Forty-five patients (PCNSL, N = 34; PVRL, N = 11) were assessable for response. The ORR at the end of induction was 35.6% (95% CI 21.9-51.2) in assessable patients and 32.0% (95% CI 21.9-51.2) in the intent-to-treat analysis, including 13 complete responses (CR)/unconfirmed CR (uCR; 29%) and 3 partial responses (PR; 7%). The best responses were 18 CR/uCR (40%) and 12 PR (27%) during the induction phase. The maintenance phase was started and completed by 18 and 5 patients, respectively. With a median follow-up of 19.2 months (range 1.5-31), the median progression-free survival (PFS) and overall survival (OS) were 7.8 months (95% CI 3.9-11.3) and 17.7 months (95% CI 12.9 to not reached), respectively. No unexpected toxicity was observed. The peripheral baseline CD4/CD8 ratio impacted PFS [median PFS = 9.5 months (95% CI, 8.1-14.8] for CD4/CD8 ≥ 1.6; median PFS = 2.8 months, [95% CI, 1.1-7.8) for CD4/CD8 < 1.6, P = 0.03).The R2 regimen showed significant activity in R/R PCNSL and PVRL patients. These results support assessments of the efficacy of R2 combined with methotrexate-based chemotherapy as a first-line treatment of PCNSL.NCT01956695