FcεRIγ-negative NK cells persist in vivo and enhance efficacy of therapeutic monoclonal antibodies in multiple myeloma.

Monoclonal antibodies (mAbs) are a central component of therapy for hematologic malignancies. Widely used mAb agents in multiple myeloma (MM) include daratumumab and elotuzumab. However, not all patients respond to these agents, and resistance is a significant clinical issue. A recently discovered subset of human natural killer (NK) cells lacking expression of FcεRIγ (g-NK cells) was found to have a multifold increase in antibody-dependent effector functions after CD16 crosslinking. In this study, we tested the capacity of g-NK cells to enhance the efficacy of therapeutic mAbs against MM. In vitro, we found that g-NK cells have strikingly superior anti-myeloma cytotoxicity compared with conventional NK (cNK) cells when combined with daratumumab or elotuzumab (∼sixfold; P < .001). In addition, g-NK cells naturally expressed minimal surface CD38 and SLAMF7, which reduced the incidence of therapeutic fratricide. In tumor-naïve murine models, the persistence of g-NK cells in blood and spleen was >10 times higher than that of cNK cells over 31 days (P < .001). In vivo efficacy studies showed that the combination of daratumumab and g-NK cells led to a >99.9% tumor reduction (by flow cytometry analysis) compared with the combination of daratumumab and cNK cells (P < .001). Moreover, treatment with daratumumab and g-NK cells led to complete elimination of myeloma burden in 5 of 7 mice. Collectively, these results underscore the unique ability of g-NK cells to potentiate the activity of therapeutic mAbs and overcome limitations of current off-the-shelf NK cell therapies without the need for cellular irradiation or genetic engineering.

Effect of nano-silver, nano-copper, deconex and benzalkonium chloride on biofilm formation and expression of transcription regulatory quorum sensing gene (rh1R) in drug-resistance Pseudomonas aeruginosa burn isolates.

BACKGROUND: Biofilm forming drug-resistant Pseudomonas aeruginosa are responsible for major death in burn center of different hospitals across the globe. OBJECTIVE: The aims of this study were to evaluate the effect of nano-silver (Ag), nano-copper (Cu), and two hospital disinfectants (deconex and benzalkonium chloride) on biofilm formation and expression of transcription regulatory quorum sensing gene rh1R in P. aeruginosa burn isolates. METHODS: 28 multidrug-resistant P. aeruginosa (MDRPA) strains were isolated from patients hospitalized in the burn center of a referral hospital in Kerman, Iran. Sizes and purities of nanoparticles were checked by TEM and X-ray diffraction (XRD) analysis. The Minimal Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) of the nanoparticles (NPs), deconex and benzalkonium chloride were determined by broth microdilution method. Antibiofilm activities of these compounds were measured by microtiter assay. Polymerase chain reaction (PCR) was used for detection of qacEΔ1, cepA, copA and rhlR genes. Quantification of rhlR gene expression in presence and absence of the above compounds was carried out by relative quantitative real-time PCR (qRT-PCR). RESULTS: Benzalkonium chloride had a potent antimicrobial activity and inhibited growth of all the isolates at MIC 0.06±0.2mg/mL, while nano-Ag was effective at MIC 20±0.2mg/mL. Furthermore, 28.5% of the isolates showed strong, 25% moderate, 14% weak and 32% demonstrated no biofilm activity. Ag NPs exerted highest antibiofilm activity, follow by deconex and benzalkonium chloride. The qacEΔ1 was absent in this study, whereas 17.8% and 60.8% of the isolates were positive for cepA and copA genes. Benzalkonium chloride, Ag NPs and deconex increased the expression of rhlR gene 64, 2 and 7 folds, respectively. CONCLUSION: Our results suggest that, there is direct relationship between decrease in antibiofilm activity and increase in expression of the rhlR gene in the presence of benzalkonium chloride. Absence of qacEΔ1 gene may be contributed in sensitivity of the isolates to the above agents.

Biochemical detection of N-Acyl homoserine lactone from biofilm-forming uropathogenic Escherichia coli isolated from urinary tract infection samples.

BACKGROUND: N-Acyl homoserine lactone (AHL) is found to be the main component of quorum sensing (QS) in Gram-negative bacteria and plays an important role in biofilm formation. Little information is available regarding the role of AHL in biofilm formation in Escherichia coli (E. coli). The purpose of this investigation was to biochemically detect and characterize AHL activity in biofilm-forming uropathogenic E. coli (UPEC) isolated from urine samples of the patients with urinary tract infections (UTIs) in Kerman, Iran. METHODS: Thirty-five UPEC isolates were obtained from urine samples of the patients with UTIs referred to the Afzalipoor hospital. The isolates were identified by biochemical tests. Biofilm analyses of all the isolates were performed using the microtiter plate method at OD 490nm. N-Acyl homoserine lactone was separated from cell mass supernatants by liquid-liquid extraction (LLE) and analyzed by a colorimetric method. N-Acyl homoserine lactone functional groups were identified by Fourier Transform-Infrared Spectroscopy (FT-IR). RESULTS: The biofilm formation assay identified 10 (28.57%) isolates with strong, 16 (45.71%) with moderate, and 9 (25.71%) with weak biofilm activities. The UPEC isolates with strong and weak biofilm activities were subjected to AHL analyses. It was found that isolates with the highest AHL activities also exhibited strong adherence to microplate wells (P≤0.05). Two E. coli isolates with the highest AHL activities were selected for FT-IR spectroscopy. Peaks at 1764.33, 1377.99, and 1242.90 cm(-1) correspond to the C=O bond of the lactone ring, and the N=H and C-O bonds of the acyl chain, respectively. CONCLUSION: We found that many UPEC isolates exhibited strong biofilm formation. The control of this property by AHL may contribute to the pathogenesis of the organism in UTI's.