Antimicrobial Microwebs of DNA–Histone Inspired from Neutrophil Extracellular Traps

Abstract

with antimicrobial protein granules and enzymes. [5] NETs have been observed to be lethal to a number of bacteria, [6] fungi, [7] viruses, [8] and parasites, [9] yet some pathogenic bacteria can evade NET-induced killing. [10,11] Accumulation of excessive NETs in vivo is also associated with pathology of bacterial biofilm, autoimmune disease, and even cancer. [12] These complex and sometimes contradictory observations highlight the need to investigate NET-related physiological interactions with simpler but defined NET-like biomaterials. Isolation of NETs from neutrophils requires repeated centrifugation and washing steps, [13] which often causes unpredictable loss of proteins. Moreover, NETs can be triggered via chemical stimulus, [14] virulence factors, [15] and bacteria [16] under different pathways, yielding 33 common proteins and as much as 50 variable proteins. [12] While the existing antibodies and inhibitors are employed to block and characterize the function of specific NET components, their high complexity imposes limitations. [17] Here, we take a bottom-up approach of synthesizing NET-like materials with defined composition, termed "microwebs," through sonochemical complexation of lambda phage DNA and histone in aqueous solutions. Lambda phage DNA can spontaneously polymerize into networks in the presence of histone, [18] which facilitates formation of web-like structure. Escherichia coli UTI89 was used as a model pathogen Neutrophil extracellular traps (NETs) are decondensed chromatin networks released by neutrophils that can trap and kill pathogens but can also paradoxically promote biofilms. The mechanism of NET functions remains ambiguous, at least in part, due to their complex and variable compositions. To unravel the antimicrobial performance of NETs, a minimalistic NET-like synthetic structure, termed "microwebs," is produced by the sonochemical complexation of DNA and histone. The prepared microwebs have structural similarity to NETs at the nanometer to micrometer dimensions but with welldefined molecular compositions. Microwebs prepared with different DNA to histone ratios show that microwebs trap pathogenic Escherichia coli in a manner similar to NETs when the zeta potential of the microwebs is positive. The DNA nanofiber networks and the bactericidal histone constituting the microwebs inhibit the growth of E. coli. Moreover, microwebs work synergistically with colistin sulfate, a common and a last-resort antibiotic, by targeting the cell envelope of pathogenic bacteria. The synthesis of microwebs enables mechanistic studies not possible with NETs, and it opens new possibilities for constructing biomimetic bacterial microenvironments to better understand and predict physiological pathogen responses. Biomimetics Nature uses a variety of extracellular nanofibers, such as cobwebs, [1] amyloid plaques, [2] and fibrin clots [3] to capture invading microbes. As part of human innate immunity, neutrophils squirt decondensed chromatin networks to capture and disarm bacteria and fungi-a host defense pro...

Networks that stop the flow: A fresh look at fibrin and neutrophil extracellular traps

“…For instance, DNA enhances mechanical stability of fibrin clots, which is already increased in the presence of histones [49], while addition of DNA does not seem to have any additional effect on the tPA-induced degradation of plasma clots supplemented with histones [48]. In synthetic NET-like microwebs, addition of DNA reduces the microbicidal activity of histones [90]. When added to coagulation assays in octamer forms, which is closer to their DNA-bound state, histones show reduced procoagulant activity [45].…”

Rational Design of Transparent Nanowire Architectures with Tunable Geometries for Preventing Marine Fouling

“…To demonstrate that our NW arrays possess similar biocidal properties, we analyzed the surfaces after 5 days of fouling test through fluorescent microscopic imaging using LIVE/DEAD bacteria stains. [ 24 ] In Figure a, we observe an increased fluorescence signal from total‐cell dye (fluorescent color: green) as inter‐NW spacing increases. This is consistent with the trends shown in Figure 4d, wherein the fouling rate increases with increasing inter‐NW spacing.…”

Antimicrobial Defensin and DNA Traps in Manila Clam Ruditapes philippinarum: Implications for Their Roles in Immune Responses

“…Hemocytes (1 × 10 6 cells/mL) were treated with LPS (500 ng/mL) for 30 min to form ETs. ETs isolated from hemocytes were dispersed into PBS by sonication, referring to the method of Song et al (2019). The ETs suspension was diluted to 50 µg/mL and incubated with V. parahaemolyticus (1 × 10 6 CFU/mL) for 1 h or not.…”