Aryl-functionalised α,α'-Trehalose 6,6'-Glycolipid Induces Mincle-independent Pyroptotic Cell Death.

α,α'-Trehalose 6,6'-glycolipids have long been known for their immunostimulatory properties. The adjuvanticity of α,α'-trehalose 6,6'-glycolipids is mediated by signalling through the macrophage inducible C-type lectin (Mincle) and the induction of an inflammatory response. Herein, we present an aryl-functionalised trehalose glycolipid, AF-2, that leads to the release of cytokines and chemokines, including IL-6, MIP-2 and TNF-α, in a Mincle-dependent manner. Furthermore, plate-coated AF-2 also leads to the Mincle-independent production of IL-1ß, which is unprecedented for this class of glycolipid. Upon investigation into the mode of action of plate-coated AF-2, it was observed that the treatment of WT and Mincle-/- bone marrow derived macrophages (BMDM), murine RAW264.7 cells, and human monocytes with AF-2 led to lytic cell death, as evidenced using Sytox Green and lactate dehydrogenase assays, and confocal and scanning electron microscopy. The requirement for functional Gasdermin D and Caspase-1 for IL-1ß production and cell death by AF-2 confirmed pyroptosis as the mode of action of AF-2. The inhibition of NLRP3 and K+ efflux reduced AF-2 mediated IL-1ß production and cell death, and allowed us to conclude that AF-2 leads to Capase-1 dependent NLRP3 inflammasome-mediated cell death. The unique mode of action of plate-coated AF-2 was surprising and highlights how the physical presentation of Mincle ligands can lead to dramatically different immunological outcomes.

A hydroalcoholic extract of Senecio nutans SCh. Bip (Asteraceae); its effects on cardiac function and chemical characterization.

ETHNOPHARMACOLOGY RELEVANCE: The plant Senecio nutans SCh. Bip. is used by Andean communities to treat altitude sickness. Recent evidence suggests it may produce vasodilation and negative cardiac inotropy, though the cellular mechanisms have not been elucidated. PURPOSE: To determinate the mechanisms action of S. nutans on cardiovascular function in normotensive animals. METHODS: The effect of the extract on rat blood pressure was measured with a transducer in the carotid artery and intraventricular pressure by a Langendorff system. The effects on sheep ventricular intracellular calcium handling and contractility were evaluated using photometry. Ultra-high-performance liquid-chromatography with diode array detection coupled with heated electrospray-ionization quadrupole-orbitrap mass spectrometric detection (UHPLC-DAD-ESI-Q-OT-MSn) was used for extract chemical characterization. RESULTS: In normotensive rats, S. nutans (10 mg/kg) reduced mean arterial pressure (MAP) by 40% (p < 0.05), causing a dose-dependent coronary artery dilation and decreased left ventricular pressure. In isolated cells, S. nutans extract (1 µg/ml) rapidly reduced the [Ca2+]i transient amplitude and sarcomere shorting by 40 and 49% (p < 0.001), respectively. The amplitude of the caffeine evoked [Ca2+]i transient was reduced by 24% (p < 0.001), indicating reduced sarcoplasmic reticulum (SR) Ca2+ content. Sodium-calcium exchanger (NCX) activity increased by 17% (p < 0.05), while sarcoendoplasmic reticulum Ca2+-ATPase (SERCA) activity was decreased by 21% (p < 0.05). LC-MS results showed the presence of vitamin C, malic acid, and several antioxidant phenolic acids reported for the first time. Dihydroeuparin and 4-hydroxy-3-(3-methylbut-2-enyl) acetophenone were abundant in the extract. CONCLUSION: In normotensive animals, S. nutans partially reduces MAP by decreasing heart rate and cardiac contractility. This negative inotropy is accounted for by decreased SERCA activity and increased NCX activity which reduces SR Ca2+ content. These results highlight the plant's potential as a source of novel cardio-active phytopharmaceuticals or nutraceuticals.

Niobium-tantalum oxide as a material platform for linear and nonlinear integrated photonics.

Here we realize the first reported integrated photonic devices fabricated using sputtered niobium-tantalum oxide films. Sputtered niobium-tantalum oxide films are highly promising for integrated photonics as they are scalable to high volume manufacturing, possess high refractive index, and are transparent in the ultraviolet through near infrared wavelength range. At a wavelength near 1550 nm, we observe propagation losses as low as 0.47 dB/cm in waveguides and ring resonators with resonator quality factors as high as 860,000. We also characterize the nonlinear performance of these films and find a Kerr coefficient (n2) of 1.2 ( ± 0.2) × 10-18 m2/W. With this high Kerr coefficient we demonstrate optical parametric oscillation in a ring resonator and supercontinuum generation in a waveguide.

Trehalose diamide glycolipids augment antigen-specific antibody responses in a Mincle-dependent manner.

Many studies have investigated how trehalose glycolipid structures can be modified to improve their Macrophage inducible C-type lectin (Mincle)-mediated adjuvanticity. However, in all instances, the ester-linkage of α,ά-trehalose to the lipid of choice remained. We investigated how changing this ester-linkage to an amide influences Mincle signalling and agonist activity and demonstrated that Mincle tolerates this functional group change. In in vivo vaccination studies in murine and ovine model systems, using OVA or Mannheimia haemolytica and Mycoplasma ovipneumoniae as vaccine antigens, respectively, it was demonstrated that a representative trehalose diamide glycolipid was able to enhance antibody-specific immune responses. Notably, IgG titres against M. ovipneumoniae were significantly greater when using trehalose dibehenamide (A-TDB) compared to trehalose dibehenate (TDB). This is particularly important as infection with M. ovipneumoniae predisposes sheep to pneumonia.

Cholesteryl glucosides signal through the carbohydrate recognition domain of the macrophage inducible C-type lectin (mincle).

Cholesteryl α-d-glucosides (αGCs) are unique metabolic products of the cancer-causing human pathogen Helicobacter pylori. Via signalling through the Macrophage inducible C-type lectin (Mincle) and the induction of a pro-inflammatory response, they are thought to play a role in the development of gastric atrophy. Herein, we prepared the first library of steryl d-glucosides and determined that they preferentially signal through the carbohydrate recognition domain of human Mincle, rather than the amino acid consensus motif. Lipidated steryl d-glucosides exhibited enhanced Mincle agonist activity, with C18 cholesteryl 6-O-acyl-α-d-glucoside (2c) being the most potent activator of human monocytes. Despite exhibiting strong Mincle signalling, sito- (5b) and stigmasterol glycosides (6b) led to a poor inflammatory response in primary cells, suggesting that Mincle is a potential therapeutic target for preventing H. pylori-mediated inflammation and cancer.

ortho-Substituted lipidated Brartemicin derivative shows promising Mincle-mediated adjuvant activity.

The macrophage inducible C-type lectin (Mincle) is a pathogen recognition receptor (PRR) that is a promising target for the development of Th1-polarising vaccine adjuvants. We recently reported on the synthesis and evaluation of lipidated Brartemicin analogues that showed Mincle agonist activity, with our lead agonist exhibiting potent Th1 adjuvant activity that was greater than that of trehalose dibehenate (TDB). Herein, we report on the efficient synthesis and subsequent biological evaluation of additional lipidated Brartemicin analogues that were designed to determine the structural requirements for optimal Mincle signalling. While all the Brartemicin analogues retained their ability to signal through Mincle and induce a functional response, the o-substituted and m,m-disubstituted derivatives (5a and 5d, respectively) induced a potent inflammatory response when using cells of both murine and human origin, with this response being the greatest observed thus far. As the inflammatory response elicited by 5a was slightly better than that induced by 5d, our findings point to o-substituted Brartemicin analogues as the preferred scaffold for further adjuvant development.

The effects of trehalose glycolipid presentation on cytokine production by GM-CSF macrophages.

Trehalose glycolipids (TGLs) are promising vaccine adjuvants, however effects of glycolipid presentation in the in vitro evaluation, and ultimate selection, of lead vaccine adjuvants are often overlooked. To this end, we synthesised a variety of TGLs and determined how the physicochemical presentation of these lipids influenced the cytokine response by bone marrow derived macrophages (BMMs). The TGLs were presented to wild-type and Mincle-/- BMMs as micellar solutions, coated on plates, coated on beads or surfactant solubilised. Medium to long-chain TGLs, either coated on plates or surfactant solubilised, resulted in the highest BMM activation. Stimulation of BMMs with TGLs coated on beads led to a decreased cytokine response, as compared to TGLs alone. All the TGL responses were Mincle dependent, however the mode of presentation did not have the same effect for each individual TGL. This was most apparent for the C22 trehalose monoester, which showed reduced activity compared to its diester counterpart when presented on a plate, but similar activity to the diester when presented as micelles or on beads. Taken together, our findings support the use of several in vitro assays for selecting lead vaccine adjuvants, particularly if structural differences between the adjuvants are pronounced. Graphical abstract The mode of glycolipid presentation, such as micellar solutions, coated on plates, coated on beads or surfactant solubilised, influences the immune response to trehalose glycolipids.

Secure communications using nonlinear silicon photonic keys.

We present a secure communication system constructed using pairs of nonlinear photonic physical unclonable functions (PUFs) that harness physical chaos in integrated silicon micro-cavities. Compared to a large, electronically stored one-time pad, our method provisions large amounts of information within the intrinsically complex nanostructure of the micro-cavities. By probing a micro-cavity with a rapid sequence of spectrally-encoded ultrafast optical pulses and measuring the lightwave responses, we experimentally demonstrate the ability to extract 2.4 Gb of key material from a single micro-cavity device. Subsequently, in a secure communication experiment with pairs of devices, we achieve bit error rates below 10-5 at code rates of up to 0.1. The PUFs' responses are never transmitted over the channel or stored in digital memory, thus enhancing the security of the system. Additionally, the micro-cavity PUFs are extremely small, inexpensive, robust, and fully compatible with telecommunications infrastructure, components, and electronic fabrication. This approach can serve one-time pad or public key exchange applications where high security is required.

Lipidated Brartemicin Analogues Are Potent Th1-Stimulating Vaccine Adjuvants.

Effective Th1-stimulating vaccine adjuvants typically activate antigen presenting cells (APCs) through pattern recognition receptors (PRRs). Macrophage inducible C-type lectin (Mincle) is a PRR expressed on APCs and has been identified as a target for Th1-stimulating adjuvants. Herein, we report on the synthesis and adjuvanticity of rationally designed brartemicin analogues containing long-chain lipids and demonstrate that they are potent Mincle agonists that activate APCs to produce inflammatory cytokines in a Mincle-dependent fashion. Mincle binding, however, does not directly correlate to a functional immune response. Mutation studies indicated that the aromatic residue of lead compound 9a has an important interaction with Mincle Arg183. In vivo assessment of 9a highlighted the capability of this analogue to augment the Th1 response to a model vaccine antigen. Taken together, our results show that lipophilic brartemicin analogues are potent Mincle agonists and that 9a has superior in vivo adjuvant activity compared to TDB.

Pump-degenerate phase-sensitive amplification in amorphous silicon waveguides.

We demonstrate phase-sensitive amplification in hydrogenated amorphous silicon photonic waveguides based on pump-degenerate four-wave mixing at continuous-wave (CW) operation, as well as at repetition rates of both 90 MHz and 10 GHz. At 90 MHz pulsed operation, an 11.7 dB phase-sensitive extinction ratio (ER) is achieved with a peak pump power of 1.6 W. At 10 GHz pulsed operation, a 6.6 dB phase-sensitive ER is achieved with a peak pump power of 0.5 W. At CW operation, a 1.6 dB ER is achieved with a pump power of 38 mW.

Silicon photonic physical unclonable function.

Physical unclonable functions (PUFs) serve as a hardware source of private information that cannot be duplicated and have applications in hardware integrity and information security. Here we demonstrate a photonic PUF based on ultrafast nonlinear optical interactions in a chaotic silicon micro-cavity. The device is probed with a spectrally-encoded ultrashort optical pulse, which nonlinearly interacts with the micro-cavity. This interaction produces a highly complex and unpredictable, yet deterministic, ultrafast response that can serve as a unique "fingerprint" of the cavity and as a source of private information for the device's holder. Experimentally, we extract 17.1-kbit binary keys from six different photonic PUF designs and demonstrate the uniqueness and reproducibility of these keys. Furthermore, we experimentally test exact copies of the six photonic PUFs and demonstrate their unclonability due to unavoidable fabrication variations.

Wavelength multicasting through four-wave mixing with an optical comb source.

Based on four-wave mixing (FWM) with an optical comb source (OCS), we experimentally demonstrate 26-way or 15-way wavelength multicasting of 10-Gb/s differential phase-shift keying (DPSK) data in a highly-nonlinear fiber (HNLF) or a silicon waveguide, respectively. The OCS provides multiple spectrally equidistant pump waves leading to a multitude of FWM products after mixing with the signal. We achieve error-free operation with power penalties less than 5.7 dB for the HNLF and 4.2 dB for the silicon waveguide, respectively.

Four-wave mixing Bragg scattering in hydrogenated amorphous silicon waveguides.

We demonstrate 15% on-chip conversion efficiency of four-wave mixing Bragg scattering in a hydrogenated amorphous silicon waveguide with only 55 and 194 mW peak pump powers in the waveguide. The lightwaves can be maintained in the telecommunication band, and the operational bandwidth is measured to be larger than 4 nm.

High-speed all-optical NAND/AND logic gates using four-wave mixing Bragg scattering.

A high-speed all-optical NAND logic gate is proposed and experimentally demonstrated using four-wave mixing Bragg scattering in highly nonlinear fiber. NAND/AND logic functions are implemented at two wavelengths by encoding logic inputs on two pumps via on-off keying. A 15.2-dB depletion of the signal is obtained for NAND operation, and time domain measurements show 10-Gb/s NAND/AND logic operations with open eye diagrams. The approach can be readily extended to higher data rates and transferred to on-chip waveguide platforms.

Wavelength-agile near-IR optical parametric oscillator using a deposited silicon waveguide.

Using a deposited hydrogenated amorphous silicon (a-Si:H) waveguide, we demonstrate ultra-broad bandwidth (60 THz) parametric amplification via four-wave mixing (FWM), and subsequently achieve the first silicon optical parametric oscillator (OPO) at near-IR wavelengths. Utilization of the time-dispersion-tuned technique provides an optical source with active wavelength tuning over 42 THz with a fixed pump wave.

Non-instantaneous optical nonlinearity of an a-Si:H nanowire waveguide.

We use pump-probe spectroscopy and continuous wave cross-phase and cross-amplitude modulation measurements to study the optical nonlinearity of a hydrogenated amorphous silicon (a-Si:H) nanowire waveguide, and we compare the results to those of a crystalline silicon waveguide of similar dimensions. The a-Si:H nanowire shows essentially zero instantaneous two-photon absorption, but it displays a strong, long-lived non-instantaneous nonlinearity that is both absorptive and refractive. Power scaling measurements show that this non-instantaneous nonlinearity in a-Si:H scales as a third-order nonlinearity, and the refractive component possesses the opposite sign to that expected for free-carrier dispersion.

Discovery of lipids from B. longum subsp. infantis using whole cell MALDI analysis.

Bifidobacteria are dominant members of the microbial community in the intestinal tract of infants, and studies have shown that glycolipids extracted from the cell surface of these bacteria elicit beneficial immune responses. Accordingly, the identification and structural characterization of glycolipids from the cell wall of bifidobacteria is the first step in correlating glycolipid structure with biological activity. Using whole cell MALDI as a screening tool, we herein present for the first time the identification and structural elucidation of the major polar lipids from Bifidobacterium longum subs. infantis. The lipids identified include an unprecedented plasmenyl cyclophosphatidic acid and a mixed acetal glycolipid, with the latter subsequently being isolated and found to suppress the innate immune response.

Multichannel photon-pair generation using hydrogenated amorphous silicon waveguides.

We demonstrate highly efficient photon-pair generation using an 8 mm long hydrogenated amorphous silicon (a-Si:H) waveguide in far-detuned multiple wavelength channels simultaneously, measuring a coincidence-to-accidental ratio as high as 400. We also characterize the contamination from Raman scattering and show it to be insignificant over a spectrum span of at least 5 THz. Our results highlight a-Si:H as a potential high-performance, CMOS-compatible platform for large-scale quantum applications, particularly those based on the use of multiplexed quantum signals.

Highly sensitive ultrafast pulse characterization using hydrogenated amorphous silicon waveguides.

We experimentally demonstrate frequency resolved optical gating (FROG) via four-wave mixing (FWM) in ultrahigh nonlinearity hydrogenated amorphous silicon waveguides. We demonstrate FROG characterization using a FWM architecture that mimics second harmonic generation (SHG) FROG for pulsewidths as low as 360 fs. Additionally, we demonstrate for the first time a FWM architecture analogous to third harmonic generation (THG) FROG and validate its ability to overcome the direction of time ambiguity of the SHG-like architecture. Both architectures allow for sensitivities suitable for future telecommunications signals.