Effective suppression of cardiac tachyarrhythmias and shortening of action potential duration (APD) remain major challenges in cardiac optogenetics due to the non-selectivity of ion-conducting channelrhodopsins (ChRs). We present a comprehensive theoretical analysis of optogenetic suppression of electrical activity and temporally precise shortening of APD in human ventricular cardiomyocytes (HVCMs) expressed with WiChR and HcKCR1 potassium (K⁺)-selective ChRs that exhibit reversal potentials close to the diastolic membrane potential of the targeted cardiac cells. Our simulations show that K⁺-selective ChRs provide more efficient hyperpolarizing control compared to cation-selective variants. Our computational simulations show that WiChR exhibits action-potential suppression at very low irradiance (4 × 10⁻² mW/mm²), while HcKCR1 could not achieve full suppression at 10 mW/mm². This makes WiChR a much stronger and more effective option for optical inhibition in human ventricular cardiomyocytes. At irradiance of 1 × 101 mW/mm², our simulations show that WiChR hyperpolarizes the membrane to -83.14 mV, closely approaching the K⁺ equilibrium potential, whereas HcKCR1 reached − 82.39 mV. The results are important for the treatment of cardiac arrhythmias and long QT syndrome. This work provides mechanistic insight into low-power optogenetic control of cardiac electrophysiology and offers quantitative predictions to guide future in vitro and in vivo investigations aimed at developing safer and more precise alternatives to electrical pacing and defibrillation technologies.

Intracellular calcium ([Formula: see text]) signaling at synapses is fundamental to understanding how the brain processes information, learns and stores memories. However, achieving precise control over calcium dynamics at the level of individual synapses remains a major challenge in neuroscience. Recent advances in calcium-permeable channelrhodopsins (CapChRs) provide a promising optogenetic strategy for directly modulating postsynaptic calcium influx with high spatial and temporal precision. Here, we present a new theoretical model of synergistic sono-optogenetic control of postsynaptic [Formula: see text]dynamics using CapChR1, CapChR2, C2-LC and PsCatCh2.0 expressed at the postsynaptic spine. We systematically explored multiple stimulation paradigms, including coordinated electrical activation of presynaptic and postsynaptic terminals, optogenetic excitation of CapChR-expressing spines, ultrasound (US) stimulation of pre- and postsynaptic terminals using MscL-I92L and combined synergistic sono-opto stimulation. These approaches reveal multiple tunable pathways for shaping postsynaptic calcium responses, with optical irradiance and US providing an additional degree of control over [Formula: see text]influx. Our analysis identifies the minimum optical irradiance, optimal inter-stimulus timing and stimulation frequency ranges required to effectively modulate synaptic efficacy. Robust synaptic modulation is achieved at an irradiance of 7 µW/mm² when electrical stimulation of the presynaptic terminal and postsynaptic spine is combined with US and optogenetic activation of CapChR2 at the postsynaptic spine, a significant 61.11% reduction from the previously reported irradiance of 18 µW/mm² in our earlier study Dixit et al. (2025). Similarly, the required irradiance is 8 µW/mm² for CapChR1, 10 µW/mm² for C2-LC, and 34 µW/mm² for PsCatCh2.0. Collectively, these results demonstrate that integrating sonogenetics with synaptic plasticity provides a flexible and energy-efficient strategy for directly controlling [Formula: see text]-dependent synaptic plasticity, substantially reducing the optical power required for effective synaptic modulation.

The present challenge in neuroscience is to non-invasively exercise low-power and high-fidelity control of neurons situated deep inside the brain. Although, two-photon optogenetic excitation can activate neurons to millimeter depth with sub-cellular specificity and millisecond temporal resolution, it can also cause heating of the targeted tissue. On the other hand, sonogenetics can non-invasively modulate the cellular activity of neurons expressed with mechano-sensitive proteins in deeper areas of the brain with less spatial selectivity. We present a theoretical analysis of a synergistic sono-optogenetic method to overcome these limitations by co-expressing a mechano-sensitive (MscL-I92L) ion-channel with a light-sensitive (CoChR/ChroME2s/ChRmine) ion-channel in hippocampal neurons. It is shown that in the presence of low-amplitude subthreshold ultrasound pulses, the two-photon excitation threshold for neural spiking reduces drastically by 73% with MscL-I92L-CoChR (0.021 mW/µm2), 66% with MscL-I92L-ChroME2s (0.029 mW/µm2), and 64% with MscL-I92L-ChRmine (0.013 mW/µm2) at 5 Hz. It allows deeper excitation of up to 1.2 cm with MscL-I92L-ChRmine combination. The method is useful to design new experiments for low-power deep excitation of neurons and multimodal neuroprosthetic devices and circuits.

Here, Bi2Se3 thin film was deposited on SnSe through r.f. magnetron sputtering system and investigated the photoelectrochemical (PEC) characteristics. Field emission scanning electron microscopy revealed the hollow nanorod's surface of SnSe thin film whereas nanoflake surface was seen for Bi2Se3 decorated SnSe. The x-ray diffraction (XRD) and Raman spectra confirmed the formation of rhombohedral Bi2Se3 and orthorhombic SnSe phase. Electronic properties of heterojunction were also studied using x-ray photoelectron spectroscopy (XPS). The PEC measurements demonstrate that the Bi2Se3/SnSe/Ti heterostructure exhibits enhanced photocatalytic performance with an obtained photocurrent density of 147.3 mu A/cm2 which was found more than 2 times that of pristine SnSe/Ti in 0.5 M Na2SO4 aqueous electrolyte under AM 1.5 G solar radiation.

Ultrafast reverse saturable absorption (RSA) in chromophore-based borondipyrro-methenes (BODIPYs) derivatives, 1,7-Diphenyl-3,5-bis(9,9-dimethyl-9H-fluoren-2-yl)-boron-diuoride-azadipyrromethene (ZL-61) and 1,7-Diphenyl-3,5-bis(4-(1,2,2-triphenyl-vinyl)phenyl)-boron-diuoride azadipyrromethene (ZL-22), has been theoretically analyzed with femtosecond (fs) laser pulses at 800 nm and 850 nm. The results are in good agreement with the reported experimental results. The effect of input pulse intensity, pulse width, nonlinear absorption (NLA) coefficients, sample thickness and laser pulse shaping on transmittance has been studied and optimized for high contrast and low-power operation. All-optical fs NOT and the universal NOR and NAND Boolean logic gates have been designed with ZL-61 and ZL-22. The logic gates with top-hat input pulse profile have a sharp switch ON/OFF time compared to the Gaussian input laser profile. Ultrafast operation at relatively low pump intensities opens up exciting prospects for the applicability of BODIPY derivatives for ultrafast low-power all-optical computing and information processing.

A detailed theoretical analysis of ultrafast intensity-dependent Saturable Absorption (SA) to Reverse Saturable Absorption (RSA) transition in CoTCPP SURMOF nanofilms has been presented with femtosecond (fs) laser pulses at 400nm. The effect of input pulse intensity, sample thickness, concentration, and 3rd and 5th order nonlinear absorption (NLA) coefficients on transmittance has been studied in detail and optimized for high contrast and low-power operation. The maximum modulation achieved for RSA is 55% at 62GW/cm(2). The results have been used to design all-optical fs-NOT, AND, OR, XOR and the universal NOR and NAND logic gates with 400nm thick CoTCPP SURMOF nanofilms. The modulation achieved for all-optical universal NAND logic gate is 45% at I-o = 55GW/cm(2). All-optical encryption and decryption for information security has been demonstrated based on all-optical XOR logic gates which offers high bit rate of 9Tbits/s at I-o = 55GW/cm(2) for secure data transmission without any optoelectronic conversion delays. An all-optical passive diode has also been theoretically designed with 17dB nonreciprocity. Ultrafast operation at relatively low input intensities opens up interesting prospects for the applicability of CoTCPP SURMOF nanofilms for ultrafast all-optical computing and information processing.

Vision restoration is one of the most promising applications of optogenetics. However, it is limited due to the poor-sensitivity, slow-kinetics and narrow band absorption spectra of opsins. Here, a detailed theoretical study of retinal ganglion neurons (RGNs) expressed with ChRmine, ReaChR, CoChR, CatCh and their mutants, with near monochromatic LEDs, and broadband sunlight, halogen lamp, RGB LED light, and pure white light sources has been presented. All the opsins exhibit improved light sensitivity and larger photocurrent on illuminating with broadband light sources compared to narrow band LEDs. ChRmine allows firing at ambient sunlight (1.5 nW/mm2) and pure white light (1.2 nW/mm2), which is lowest among the opsins considered. The broadband activation spectrum of ChRmine and its mutants is also useful to restore color sensitivity. Although ChRmine exhibits slower turn-off kinetics with broadband light, high-fidelity spikes can be evoked upto 50 Hz. This limit extends upto 80 Hz with the improved hsChRmine mutant although it requires double the irradiance compared to ChRmine. The present study shows that ChRmine and its mutants allow activation of RGNs with ambient light which is useful for goggle-free white light optogenetic retinal prostheses with improved quality of restored vision.

Ultrafast reverse saturable absorption has been analyzed in detail in chromophore-based borondipyrromethenes (BODIPYs) derivatives with femtosecond (fs) laser pulses at 800 nm and 850 nm. The effect of pulse intensity, pulse-width, thickness, concentration, nonlinear absorption coefficients and laser pulse shaping on transmittance has been studied and optimized for the all-optical switching in recently discovered BODIPY derivatives, 1,7-Diphenyl-3,5-bis(9,9-dimethyl-9H-fluoren-2-yl)-boron-diuoride-azadipyrromethene (ZL-61) and 1,7-Diphenyl-3,5-bis(4-(1,2,2-triphenylvinyl) phenyl)-boron-diuoride azadipyrromethene (ZL-22). The results have been used to design low-power and high-contrast all-optical fs NOT, universal NOR, and NAND logic gates. The ZL-61 at 800 nm and 850 nm results in enhanced contrast than ZL-22 and therefore, all-optical logic gates with ZL-61 have better percentage modulation. The excellent nonlinear optical properties of organic molecules and their derivatives have tremendous potential for ultrafast all-optical computing and ultrahigh bandwidth information processing.

This prospective single-arm study demonstrated the vital role of SBRT in the treatment of Hepatocellular carcinoma with Portal vein tumor thrombosis and its efficacy in terms of achieving excellent local control with relatively lesser toxicities compared with existing treatment modalities. Patients have shown benefit post-treatment in terms of thrombus reduction and restoration of Portal vein flow making them suitable for further treatment like Resection or TACE.

The fundamental process of information processing and memory formation in the brain is associated with complex neuron firing patterns, which can occur spontaneously or be triggered by sensory inputs. Optogenetics has revolutionized neuroscience by enabling precise manipulation of neuronal activity patterns in specified neural populations using light. However, the light pulses used in optogenetics have been primarily restricted to square waveforms. Here, we present a detailed theoretical analysis of the temporal shaping of light pulses in optogenetic excitation of hippocampal neurons and neocortical fast-spiking interneurons expressed with ultrafast (Chronos), fast (ChR2), and slow (ChRmine) channelrhodopsins. Optogenetic excitation has been studied with light pulses of different temporal shapes that include square, forward-/backward ramps, triangular, left-/right-triangular, Gaussian, left-/right-Gaussian, positive-sinusoidal, and left-/right-positive sinusoidal. Different light shapes result in significantly different photocurrent amplitudes and kinetics, spike-timing, and spontaneous firing rate. For short duration stimulations, left-Gaussian pulse results in larger photocurrent in ChR2 and Chronos than square pulse of the same energy density. Time to peak photocurrent in each opsin is minimum at right-Gaussian pulse. The optimal pulse width to achieve peak photocurrent for non-square pulses is 10 ms for Chronos, and 50 ms for ChR2 and ChRmine. The pulse energy to evoke spike in hippocampal neurons can be minimized on choosing square pulse with Chronos, Gaussian pulse with ChR2, and positive-sinusoidal pulse with ChRmine. The results demonstrate that non-square waveforms generate more naturalistic spiking patterns compared to traditional square pulses. These findings provide valuable insights for the development of new optogenetic strategies to better simulate and manipulate neural activity patterns in the brain, with the potential to improve our understanding of cognitive processes and the treatment of neurological disorders.

A major challenge in cardiac optogenetics is to have minimally invasive large volume excitation and suppression for effective cardioversion and treatment of tachycardia. It is important to study the effect of light attenuation on the electrical activity of cells in in vivo cardiac optogenetic experiments. In this computational study, we present a detailed analysis of the effect of light attenuation in different channelrhodopsins (ChRs)-expressing human ventricular cardiomyocytes. The study shows that sustained illumination from the myocardium surface used for suppression, simultaneously results in spurious excitation in deeper tissue regions. Tissue depths of suppressed and excited regions have been determined for different opsin expression levels. It is shown that increasing the expression level by 5-fold enhances the depth of suppressed tissue from 2.24 to 3.73 mm with ChR2(H134R) (ChR2 with a single point mutation at position H134), 3.78 to 5.12 mm with GtACR1 (anion-conducting ChR from cryptophyte algae Guillardia theta) and 6.63 to 9.31 mm with ChRmine (a marine opsin gene from Tiarina fusus). Light attenuation also results in desynchrony in action potentials in different tissue regions under pulsed illumination. It is further shown that gradient-opsin expression not only enables suppression up to the same level of tissue depth but also enables synchronized excitation under pulsed illumination. The study is important for the effective treatment of tachycardia and cardiac pacing and for extending the scale of cardiac optogenetics.

Supplying power at low voltage to the front-end electronics of very fast and highly segmented detectors, typical in the experiments at the Large Hadron Collider, involves several issues, including transient currents and voltages. This study investigates a power chain that involves long cables, DC-DC converters, and input filters. Due to the presence of a common ground close to the input of the DC-DC converter, the power chain can run with a lower value of the input supply. It is seen that the capacitor in the input filter plays a significant role in the process of voltage growth at the input of the DC-DC converter. The effects of the ramp during turning ON and OFF the input supply have been studied thoroughly. It is observed that the voltage/current spikes are reduced due to the application of the ramp. It is also observed that the current/voltage, both at the input and the output of the DC-DC converter, goes through some intermediate oscillations due to the existence of threshold voltage for the converters. The choice of the ramp is critical in reducing spikes and should be incorporated into the power supply.

We present a detailed theoretical analysis of ultrafast saturable absorption (SA) and reverse SA (RSA) in MoTe 2 nano-films with femtosecond (fs) laser pulses at 800 nm. A transition from RSA to SA occurs on increasing the thickness from 30 nm to 80 nm at a constant pump intensity of 141 GW cm −2 . On the other hand, a transition from SA to RSA occurs upon increasing the pump intensity in an 80 nm thick MoTe 2 nano-film. Theoretical results are in good agreement with reported experimental results. The effect of pump pulse intensity, pulse width, nonlinear absorption coefficient and sample thickness has been studied to optimize the SA ↔ RSA transition. The results for low-power and high contrast all-optical switching in MoTe 2 nano-films have been used to design all-optical fs NOT, OR, AND, as well as the universal all-optical NOR and NAND logic gates. The SA behavior of MoTe 2 /MoS 2 nanocomposite films has been used to design all-optical AND and OR logic gates. The nanocomposite films of MoTe 2 /MoS 2 possess a larger nonlinear optical response in comparison to MoTe 2 and MoS 2 nano-films and, therefore, all-optical logic gates designed using nanocomposite films result in a good switching contrast compared to pure MoTe 2 nano-films. Ultrafast operation at relatively low pump intensities demonstrates the applicability of MoTe 2 and MoTe 2 /MoS 2 nano-films for ultrafast all-optical information processing.

Low-power, high-fidelity, large volume, synchronized excitation and suppression of cardiac cells is a maj or challenge in cardiac optogenetics. Although newly discovered powerful opsins that include ChRmine, a marine opsin gene from rhodomonas lens have significantly improved the excitable tissue volume, it is important to study the effect of light attenuation. In the present study, a novel method of gradient opsin-expression has been presented for enhanced volume suppression and synchronized excitation in human ventricular cardiomyocytes using ChRmine. The delayed action potentials ~ 18.6 ms in deeper layers of the tissue can be synchronized using this novel method. Furthermore, the proposed method allows to suppress the same tissue depth~ 6.9 mm at lower expression level. It would be very useful for effective treatment of cardioversion and tachycardia, and for extending the scale of cardiac optogenetics.

Homeobox gene families are associated with embryonic development and organogenesis. Pieces of evidence suggest that these Homeobox genes are also crucial in facilitating oncogenesis when mutated or overexpressed. Paired homeodomain transcription factor-2 (PITX2), one of the members of this family, is involved in oncogenic regulation apart from its different development regulatory functions. PITX2 has been earlier shown to induce ovarian cancer cell proliferation through the activation of different signaling cascades. Increased cancer cell proliferation requires a constant supply of nutrients for both adenosine triphosphate and biomass synthesis, which is facilitated by altered cancer cell metabolism that includes enhanced glucose uptake and increased glycolytic rate. This present study highlights the involvement of PITX2 in enhancing the cellular glycolysis pathway in ovarian cancer cells through protein kinase B-phosphorylation (phospho-AKT). PITX2 expression correlates positively with that of the glycolytic rate-determining enzyme, lactate dehydrogenase-A (LDHA), in both high-grade serous ovarian cancer tissues and common ovarian cancer cell lines. Interestingly, transient localization of enzymatically active LDHA in the nucleus was observed in PITX2-overexpressed ovarian cancer cells. This nuclear LDHA produces higher concentrations of the glycolytic end product, lactate, which accumulates in the nuclear compartment resulting in decreased histone deacetylase (HDAC1/2) expression and increased histone acetylation at H3/H4. However, the mechanistic details of lactate-HDAC interaction are still elusive in the earlier reports. Our in silico studies elaborated on the interaction dynamics of lactate in the HDAC catalytic core through ligand-binding studies and molecular dynamics simulation approaches. Blocking lactate production by silencing LDHA reduced cancer cell proliferation. Thus, PITX2-induced epigenetic changes can lead to high cellular proliferation and increase the size of tumors in syngeneic mice as well. Taken together, this is the first report of its kind to show that the developmental regulatory homeobox gene PITX2 could enhance oncogenesis through enhanced glycolysis of tumor cells followed by epigenetic modifications.

All-optical devices are essential for next generation ultrafast, ultralow-power and ultrahigh bandwidth information processing systems. Silicon microring resonators (SiMRR) provide a versatile platform for all-optical switching and CMOS-compatible computing, with added advantages of high Q-factor, tunability, compactness, cascadability and scalability. A detailed theoretical analysis of ultrafast all-optical switching 2 x 2 SiMRRs has been carried out incorporating the effects of two photon absorption induced free-carrier injection and thermo optic effect. The results have been used to design simple and compact all-optical 3-bit and 4-bit pseudo-random binary sequence generators and the first reported designs of all-optical 4 x 4-bit multiplier and divider. The designs have been optimized for low-power, ultrafast operation with high modulation depth, enabling logic operations at 45 Gbps.

BackgroundEnpatoran is a selective and potent dual toll-like receptor (TLR) 7/8 inhibitor in development for the treatment of cutaneous and systemic lupus erythematosus (CLE/SLE). Enpatoran inhibits TLR7/8 activation in vitro and suppresses disease activity in lupus mouse models.1 Enpatoran was well tolerated and had linear pharmacokinetic (PK) parameters in healthy volunteers.2 As TLR7/8 mediate immune responses to single-stranded RNA viruses, including SARS-CoV-2, it was postulated that enpatoran may prevent hyperinflammation and cytokine storm in COVID-19.ObjectivesIn response to the COVID-19 pandemic, we conducted an exploratory Phase II trial to assess safety and determine whether enpatoran prevents clinical deterioration in patients (pts) hospitalized with COVID-19 pneumonia. PK and pharmacodynamics (PD) of enpatoran were also evaluated.MethodsANEMONE was a randomized, double-blind, placebo (PBO)-controlled study conducted in Brazil, the Philippines, and the USA (NCT04448756). Pts aged 18–75 years, hospitalized with COVID-19 pneumonia (WHO 9-point scale score =4) but not mechanically ventilated, with SpO2 <94% and PaO2/FiO2 ≥150 (FiO2 maximum 0.4) were eligible. Those with a history of uncontrolled illness, active/unstable cardiovascular disease and SARS-CoV-2 vaccination were excluded. Pts received PBO or enpatoran (50 or 100 mg twice daily [BID]) for 14 days, with monitoring to Day 28 and safety follow-up to Day 60. Primary outcomes were safety and time to recovery (WHO 9-point scale ≤3). Clinical deterioration (time to clinical status >4, WHO 9-point scale) was a secondary outcome. Exploratory endpoints were enpatoran and biomarker concentrations (cytokines, C-reactive protein [CRP], D-dimer and interferon gene signature [IFN-GS] scores) assessed over time.Results149 pts received either PBO (n=49), or enpatoran 50 mg (n=54) or 100 mg (n=46) BID; 88% completed treatment and 86% received concomitant steroids. Median age was 50 years (77% <60 years old), 66% were male, and 50% had ≥1 comorbidity (40% hypertension, 24% diabetes). Overall, 59% pts reported a treatment-emergent adverse event (TEAE) with three non-treatment-related deaths; 11% reported a treatment-related TEAE. The proportion of pts in the enpatoran group reporting serious TEAEs was low (50 mg BID 9%; 100 mg BID 2%) vs PBO (18%). Gastrointestinal disorders were most common (PBO 8%; 50 mg BID 28%; 100 mg BID 9%). The primary outcome of time to recovery with enpatoran vs PBO was not met; medians were 3.4–3.9 days. A positive signal in time to clinical deterioration from Day 1 through Day 28 was observed; hazard ratios [95% CI] for enpatoran vs PBO were 0.39 [0.13, 1.15] (50 mg BID) and 0.30 [0.08, 1.08] (100 mg BID). Mean enpatoran exposure was dose-proportional, and PK properties were within expectations. The median (quartile [Q]1– Q3) interleukin 6 (IL-6), CRP and D-dimer baseline concentration across the groups were 5.7 (4.0–13.5) pg/mL, 30.04 (11.40–98.02) and 0.62 (0.39–1.01) mg/L, respectively. Baseline IFN-GS scores were similar across groups.ConclusionThe ANEMONE trial was the first to evaluate the safety and efficacy of a TLR7/8 inhibitor in an infectious disease for preventing cytokine storm. Enpatoran up to 100 mg BID for 14 days was well tolerated by patients acutely ill with COVID-19 pneumonia. Time to recovery was not improved with enpatoran, perhaps due to the younger age of patients who had fewer comorbidities compared to those in similar COVID-19 trials. However, there was less likelihood for clinical deterioration with enpatoran than placebo. This trial provides important safety, tolerability, PK and PD data supporting continued development of enpatoran in SLE and CLE (NCT04647708, NCT05162586).References[1]Vlach, et al. J Pharmacol Exp Ther 2021;376:397–409;[2]Port, et al. Pharmacol Res Perspect 2021;9:e00842.AcknowledgementsWe would like to thank those who took part in the the ANEMONE trial. This study was sponsored by the healthcare business of Merck KGaA, Darmstadt, Germany (CrossRef Funder ID: 10.13039/100009945), who funded medical writing support by Bioscript Stirling Ltd.Disclosure of InterestsJohn E. McKinnon Consultant of: EMD Serono Research & Development Institute, Inc., Billerica, MA, USA, an affiliate of Merck KGaA, Joel Santiaguel Speakers bureau: Merck Healthcare KGaA, Claudia Murta Speakers bureau: Pfizer/Wyeth, Dongzi Yu Employee of: EMD Serono Research & Development institute (an affiliate of Merck KGaA), Mukhy Khursheed Employee of: Merck Serono Ltd (an affiliate of Merck KGaA), Flavie Moreau Employee of: EMD Serono Research & Development institute (an affiliate of Merck KGaA), Lena Klopp-Schulze Employee of: Merck Healthcare KGaA, Jamie Shaw Employee of: EMD Serono Research & Development institute (an affiliate of Merck KGaA), Sanjeev Roy Employee of: Ares Trading SA (an affiliate of Merck KGaA), Amy Kao Employee of: EMD Serono Research & Development institute (an affiliate of Merck KGaA)

Objective. A fundamental challenge in optogenetics is to elicit long-term high-fidelity neuronal spiking with negligible heating. Fast channelrhodopsins (ChRs) require higher irradiances and cause spike failure due to photocurrent desensitization under sustained illumination, whereas, more light-sensitive step-function opsins (SFOs) exhibit prolonged depolarization with insufficient photocurrent and fast response for high-fidelity spiking. Approach. We present a novel method to overcome this fundamental limitation by co-expressing fast ChRs with SFOs. A detailed theoretical analysis of ChETA co-expressed with different SFOs, namely ChR2(C128A), ChR2(C128S), stabilized step-function opsin (SSFO) and step-function opsin with ultra-high light sensitivity (SOUL), expressing hippocampal neurons has been carried out by formulating their accurate theoretical models. Main results. ChETA-SFO-expressing hippocampal neurons shows more stable photocurrent that overcomes spike failure. Spiking fidelity in these neurons can be sustained even at lower irradiances of subsequent pulses (77% of initial pulse intensity in ChETA-ChR2(C128A)-expressing neurons) or by using red-shifted light pulses at appropriate intervals. High-fidelity spiking upto 60 Hz can be evoked in ChETA-ChR2(C128S), ChETA-SSFO and ChETA-SOUL-expressing neurons, which cannot be attained with only SFOs. Significance. The present study provides important insights about photostimulation protocols for bi-stable switching of neurons. This new approach provides a means for sustained low-power, high-frequency and high-fidelity optogenetic switching of neurons, necessary to study various neural functions and neurodegenerative disorders, and enhance the utility of optogenetics for biomedical applications.

Background Enpatoran is a potent selective dual inhibitor of toll-like receptor (TLR) 7 and TLR8, aberrant activation of which may be involved in systemic lupus erythematosus (SLE) pathogenesis and glucocorticoid resistance. 1,2,3 Enpatoran suppressed disease development in lupus mouse models, improving survival and reducing proteinuria, autoantibodies, and the interferon (IFN) gene signature. 1 In healthy participants and patients hospitalized with COVID-19 pneumonia, enpatoran was well tolerated and demonstrated effective TLR7/8 engagement. 4 Enpatoran is potentially glucocorticoid sparing and may help avoid the detrimental effects of long-term corticosteroid use in SLE management. 5,6 Objectives To evaluate the glucocorticoid-sparing effect of enpatoran and design a basket trial to assess its efficacy and safety in patients with SLE and/or cutaneous lupus erythematosus (CLE). Methods Cytokine concentrations and gene expression changes were measured in stimulated human peripheral blood mononuclear cells (PBMCs) from healthy donors after treatment with dexamethasone, TLR7/8 inhibitor, or both. A Phase II, basket design proof-of-concept, dose-finding study in patients with SLE and/or CLE (WILLOW) was designed. Results In healthy donor PBMCs, synergy was observed between TLR7/8 inhibitor and dexamethasone. Combination treatment inhibited cytokine release (IL-6) with greater potency than either treatment alone and reduced the expression of nuclear factor-kappa B and IFN-regulated genes. WILLOW is a Phase II, basket proof-of-concept, dose-finding, randomized, double-blind, placebo (PBO)-controlled 24-week study with two cohorts ( NCT05162586 , Figure 1). The primary objectives of WILLOW are to evaluate the dose–response relationship of enpatoran in reducing disease activity based on Cutaneous Lupus Erythematosus Disease Area and Severity Index-A (CLASI-A) or BILAG-Based Composite Lupus Assessment (BICLA) response rate. The secondary objectives are to investigate effects on both BICLA response and clinically meaningful corticosteroid reduction and evaluate disease control (including clinically meaningful corticosteroid reduction) in patients with predominantly active CLE or SLE. Cohort A will enroll patients with CLE (active subacute CLE and/or discoid LE) or SLE with predominantly active lupus rash. Cohort B, in two parts, will enroll SLE patients with moderate to severe systemic disease activity. Part 1 will assess clinical signal and Part 2 may be adapted to improve dose finding. Glucocorticoid-sparing will be evaluated by mandatory tapering to a prednisone-equivalent dose of ≤5 mg/day. Figure 1. WILLOW study design. Cohort A and Cohort B Part 1 will start in parallel. *Part 2 will be initiated after a pre-specified number of patients are enrolled in Part 1; enpatoran doses in Part 2 may be adapted to improve dose finding (dashed boxes). BILAG, British Isles Lupus Assessment Group; CLASI-A, Cutaneous Lupus Erythematosus Disease Area and Severity Index-A; CLE, cutaneous lupus erythematosus; CS, corticosteroid; DBPC, double-blind placebo-controlled; DLE, discoid lupus erythematosus; PBO, placebo; SCLE, Subacute cutaneous lupus erythematosus; SLE, systemic lupus erythematosus; SLEDAI, Systemic Lupus Erythematosus Disease Activity Index. Conclusion Enpatoran is a novel TLR7/8 inhibitor and may enable glucocorticoid dose reduction in patients with SLE and CLE. The WILLOW study incorporates multiple novel elements including a basket design and evaluation of glucocorticoid-sparing. References [1]Vlach, et al. J Pharmacol Exp Ther. 2021;376:397–409; [2]Northcott, et al. Lancet Rheumatol. 2021;5:e357–e370; [3]Guiducci, et al. Nature. 2010;465:937–941; [4]Port, et al. Pharmacol Res Perspect. 2021;9:e00842; [5]Thamer, et al. J Rheumatol. 2009;36:560–564; [6]Ruiz-Irastorza, et al. Rheumatology. 2012;51:1145–1153. Acknowledgements This study was sponsored by the healthcare business of Merck KGaA, Darmstadt, Germany (CrossRef Funder ID: 10.13039/100009945), who funded medical writing support by Bioscript Stirling Ltd. Disclosure of Interests Eric F. Morand: None declared, Andrew Bender Shareholder of: Shares in Merck KGaA, Employee of: EMD Serono Research & Development institute (an affiliate of Merck KGaA), Aditee Deshpande Employee of: EMD Serono Research & Development institute (an affiliate of Merck KGaA), Bharat Vaidyanathan Employee of: EMD Serono Research & Development institute (an affiliate of Merck KGaA), cristina vazquez mateo Employee of: EMD Serono Research & Development institute (an affiliate of Merck KGaA), Melinda Przetak Employee of: EMD Serono Research & Development institute (an affiliate of Merck KGaA), Flavie Moreau Employee of: EMD Serono Research & Development institute (an affiliate of Merck KGaA), Mukhy Khursheed Employee of: Merck Serono Ltd (an affiliate of Merck KGaA), Sanjeev Roy Employee of: Ares Trading SA (an affiliate of Merck KGaA), David Pearson Consultant of: Biogen Inc.