VISTA promotes the metabolism and differentiation of myeloid-derived suppressor cells by STAT3 and polyamine-dependent mechanisms.

Myeloid-derived suppressor cells (MDSCs) impair antitumor immune responses. Identifying regulatory circuits during MDSC development may bring new opportunities for therapeutic interventions. We report that the V-domain suppressor of T cell activation (VISTA) functions as a key enabler of MDSC differentiation. VISTA deficiency reduced STAT3 activation and STAT3-dependent production of polyamines, which causally impaired mitochondrial respiration and MDSC expansion. In both mixed bone marrow (BM) chimera mice and myeloid-specific VISTA conditional knockout mice, VISTA deficiency significantly reduced tumor-associated MDSCs but expanded monocyte-derived dendritic cells (DCs) and enhanced T cell-mediated tumor control. Correlated expression of VISTA and arginase-1 (ARG1), a key enzyme supporting polyamine biosynthesis, was observed in multiple human cancer types. In human endometrial cancer, co-expression of VISTA and ARG1 on tumor-associated myeloid cells is associated with poor survival. Taken together, these findings unveil the VISTA/polyamine axis as a central regulator of MDSC differentiation and warrant therapeutically targeting this axis for cancer immunotherapy.

PERK is a critical metabolic hub for immunosuppressive function in macrophages.

Chronic inflammation triggers compensatory immunosuppression to stop inflammation and minimize tissue damage. Studies have demonstrated that endoplasmic reticulum (ER) stress augments the suppressive phenotypes of immune cells; however, the molecular mechanisms underpinning this process and how it links to the metabolic reprogramming of immunosuppressive macrophages remain elusive. In the present study, we report that the helper T cell 2 cytokine interleukin-4 and the tumor microenvironment increase the activity of a protein kinase RNA-like ER kinase (PERK)-signaling cascade in macrophages and promote immunosuppressive M2 activation and proliferation. Loss of PERK signaling impeded mitochondrial respiration and lipid oxidation critical for M2 macrophages. PERK activation mediated the upregulation of phosphoserine aminotransferase 1 (PSAT1) and serine biosynthesis via the downstream transcription factor ATF-4. Increased serine biosynthesis resulted in enhanced mitochondrial function and α-ketoglutarate production required for JMJD3-dependent epigenetic modification. Inhibition of PERK suppressed macrophage immunosuppressive activity and could enhance the efficacy of immune checkpoint programmed cell death protein 1 inhibition in melanoma. Our findings delineate a previously undescribed connection between PERK signaling and PSAT1-mediated serine metabolism critical for promoting immunosuppressive function in M2 macrophages.

Topoisomerase 2 inhibitor etoposide promotes interleukin-10 production in LPS-induced macrophages via upregulating transcription factor Maf and activating PI3K/Akt pathway.

Topoisomerase (TOP) inhibitors were commonly used as chemotherapeutic agents in the treatment of cancers. In our present study, we found that etoposide (ETO), a topoisomerase 2 (TOP2) inhibitor, upregulated the production of Interleukin 10 (IL-10) in lipopolysaccharide (LPS)-stimulated macrophages. Besides, other TOP2 inhibitors including doxorubicin hydrochloride (DOX) and teniposide (TEN) were also able to augment IL-10 production. Meanwhile, the expression levels of pro-inflammatory factors, for example IL-6 and TNF-α, were also decreased accordingly by the treatment of the TOP2 inhibitors. Of note, ETO facilitated IL-10 secretion, which might be regulated by transcription factor Maf via PI3K/AKT pathway, as pharmaceutic blockage of kinase PI3K or AKT attenuated ETO-induced Maf and IL-10 expression. Further, in LPS-induced mice sepsis model, the enhanced generation of IL-10 was observed in ETO-treated mice, whereas pro-inflammatory cytokines were decreased, which significantly reduced the mortality of mice from LPS-induced lethal cytokine storm. Taken together, these results indicated that ETO may exhibit an anti-inflammatory role by upregulating the alteration of transcription factor Maf and promoting subsequential IL-10 secretion via PI3K/Akt pathway in LPS-induced macrophages. Therefore, ETO may serve as a potential anti-inflammatory agent and employed to severe pro-inflammatory diseases including COVID-19.

Remdesivir Alleviates Acute Kidney Injury by Inhibiting the Activation of NLRP3 Inflammasome.

Acute kidney injury (AKI) is a frequent clinical complication in critically ill patients, and it rapidly develops into renal failure with high morbidity and mortality. However, other than dialysis, no effective therapeutic interventions can offer reliable treatment to limit renal injury and improve survival. Here, we firstly reported that remdesivir (RDV, GS-5734), a broad-spectrum antiviral nucleotide prodrug, alleviated AKI by specifically inhibiting NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasome activation in macrophages. Mechanically, RDV effectively suppressed the activities of nuclear transcription factor (NF)-κB, mitogen-activated protein kinase (MAPK), which further led to the reduction of the inflammasome genes of NLRP3 transcription, limiting the activation of NLRP3 inflammasome in vivo and in vitro. RDV also inhibited other pro-inflammatory genes including tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), IL-12, IL-1ß, and interferon-ß (IFN-ß), leading to the reduction of inflammatory factors release. Thus, RDV can ameliorate AKI via modulating macrophage inflammasome activation and inflammatory immune responses and may have a therapeutic potential for patients with AKI in clinical application.

Dynamic Expression of Platelet-Derived Growth Factor-D and Phosphorylated Platelet-Derived Growth Factor Receptor-Β after Traumatic Brain Injury in Rats.

BACKGROUND: We explored the dynamic expression of platelet-derived growth factor-D (PDGF-D) and phosphorylated platelet-derived growth factor receptor-ß (p-PDGFR-ß) after traumatic brain injury in rats to provide theoretical basis for selecting therapeutic target and intervention time after traumatic brain injury. METHODS: This study prepared the weight drop/impact acceleration-induced traumatic brain injury (TBI) model in rats, including sham group and TBI groups at different observation time points (6 hours, 12 hours, 24 hours, 3 days, and 7 days after TBI). The dynamic expression of PDGF-D and p-PDGFR-ß after TBI were detected by western blot and immunofluorescence staining. RESULTS: The expression level of PDGF-D and p-PDGFR-ß after TBI was detected by western blot. The PDGF-D level was increased (p < 0.05) 6 hours after TBI and remained at the high level until 3 days after TBI (p < 0.05). The p-PDGFR-ß level was increased (p < 0.05) 12 hours after TBI and remained at the high level until 3 days after TBI (p < 0.05). PDGF-D and p-PDGFR-ß in brain tissues were found by immunofluorescence in the perihematoma area 24 hours after TBI. CONCLUSIONS: This study revealed the expression phenomenon of PDGF-D and p-PDGFR-ß after TBI in rats, suggesting that PDGF-D participates in the process of secondary brain injury after TBI through specific binding with PDGFR-ß, which provides a theoretical basis for further research on selecting therapeutic targets and intervention times after TBI.

Molecular Chaperones: Molecular Assembly Line Brings Metabolism and Immunity in Shape.

Molecular chaperones are a set of conserved proteins that have evolved to assist the folding of many newly synthesized proteins by preventing their misfolding under conditions such as elevated temperatures, hypoxia, acidosis and nutrient deprivation. Molecular chaperones belong to the heat shock protein (HSP) family. They have been identified as important participants in immune functions including antigen presentation, immunostimulation and immunomodulation, and play crucial roles in metabolic rewiring and epigenetic circuits. Growing evidence has accumulated to indicate that metabolic pathways and their metabolites influence the function of immune cells and can alter transcriptional activity through epigenetic modification of (de)methylation and (de)acetylation. However, whether molecular chaperones can regulate metabolic programs to influence immune activity is still largely unclear. In this review, we discuss the available data on the biological function of molecular chaperones to immune responses during inflammation, with a specific focus on the interplay between molecular chaperones and metabolic pathways that drive immune cell fate and function.

Carbohydrate and Amino Acid Metabolism as Hallmarks for Innate Immune Cell Activation and Function.

Immune activation is now understood to be fundamentally linked to intrinsic and/or extrinsic metabolic processes which are essential for immune cells to survive, proliferate, and perform their effector functions. Moreover, disruption or dysregulation of these pathways can result in detrimental outcomes and underly a number of pathologies in both communicable and non-communicable diseases. In this review, we discuss how the metabolism of carbohydrates and amino acids in particular can modulate innate immunity and how perturbations in these pathways can result in failure of these immune cells to properly function or induce unfavorable phenotypes.

Small heat shock protein CRYAB inhibits intestinal mucosal inflammatory responses and protects barrier integrity through suppressing IKKß activity.

Alpha B-crystallin (CRYAB) is an important member of the small heat shock protein family, and plays a protective and therapeutic role in neurological inflammation. CRYAB expression was assessed in cultured HT29 and Caco-2 cells and inflamed mucosa of patients with inflammatory bowel disease (IBD) and colitis models in mice. Lentivirus-overexpressing and CRSIPR/Cas9 systems were used in different cells to upregulate and silence CRYAB expression, respectively. Cell permeable recombined fusion protein TAT-CRYAB was injected intraperitoneally into dextran sulfate sodium (DSS)- or 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis in mice to assess its anti-inflammatory effects. CRYAB was found to be significantly decreased in the inflamed mucosa from IBD patients and DSS-induced colitis in mice, and negatively correlated with the levels of TNF-α and IL-6, respectively. Enforced expression of CRYAB suppressed expression of proinflammatory cytokines (e.g., TNF-α, IL-6, IL-1ß, and IL-8) via inhibiting the IKK complex formation, whereas lack of CRYAB expression markedly enhanced proinflammatory responses. Consistently, administration of TAT-CRYAB fusion protein significantly alleviated DSS- or TNBS-induced colitis in mice and protected intestinal barrier integrity. CRYAB regulates inflammatory response in intestinal mucosa by inhibiting IKKß-mediated signaling and may serve as a novel therapeutic approach in the treatment of IBD.

Effect of high-order aberrations on pattern-reversal visual evoked potentials.

To investigate the effect of high-order aberrations (HOAs) on pattern-reversal visual evoked potentials (PR-VEPs), we measured PR-VEPs with HOAs either retained or corrected with an adaptive optics (AO) system for 12 subjects. The PR-VEPs at different spatial frequencies were recorded for the dominant eye of each subject. The results indicated that the amplitude of the first positive P1 wave at 1-16 cpd (except 2 cpd) and the second negative N2 wave at 12 and 16 cpd were raised statistically significantly with HOA correction. This confirmed the contributions of the HOAs to the alterations in PR-VEPs, and suggested that HOAs should be corrected to realize accurate PR-VEP testing.

Impact of intraocular scatter on stereopsis.

To investigate the effect of intraocular scatter on stereopsis, we measured stereoacuity with scatter either remaining at the natural eye-induced level or further enhanced by a set of three different scatter filters. Stereo thresholds at different viewing durations were obtained using a psychophysical method of constant stimuli. The results indicate that stereoacuity was degraded with a binocular increase in scatter levels for all the subjects. Measurements were also performed in the presence of interocular differences in scatter levels. In this case, stereoacuity was found to be even a little worse than that obtained with both eyes at a higher scatter level. This suggests that stereoacuity in the presence of interocular differences in scatter levels is mainly dependent on the higher scatter level.

Dynamic changes in higher-order aberrations after correction of lower-order aberrations with adaptive optics in myopic and emmetropic eyes.

This study investigated the instantaneous changes of higher-order aberrations (HOAs) following lower-order aberrations (LOAs) correction with a closed-loop adaptive optics (AO) system in myopic and emmetropic eyes. Data were analyzed using generalized additive mixed models. Time-related changes in HOAs were modeled with two-piecewise linear regressions and were compared between myopic and emmetropic eyes. Both vertical coma and spherical aberrations shifted to the positive direction immediately after LOA correction. The fluctuations of the above values were significantly faster in myopic than in emmetropic eyes. Understanding these changes in HOAs following LOA correction may help in achieving better visual outcomes.

Mesenteric CD103+DCs Initiate Switched Coxsackievirus B3 VP1-Specific IgA Response to Intranasal Chitosan-DNA Vaccine Through Secreting BAFF/IL-6 and Promoting Th17/Tfh Differentiation.

Intranasal chitosan-formulated DNA vaccination promotes IgA secretion in the intestine. However, the mechanism whereby chitosan-DNA skews IgA class switch recombination (CSR) of B cells in the Gut-associated lymph tissue (GALT) is not fully resolved. In this study, we investigated the effects of nasally administered chitosan-DNA (pcDNA3.1-VP1 plasmid encoding VP1 capsid protein of Coxsackievirus B3) on IgA production, DC activation and Tfh/Th17 response in the intestine. Compared to DNA immunization, intranasal chitosan-DNA vaccination induced antigen-specific IgA production in feces, a pronounced switching of antigen-specific IgA+ plasmablast B cells in the mesenteric lymph nodes (MLNs) and an enhanced expression of post-recombination Iα-CH transcripts/IgA germline transcript (αGT) as well as activation-induced cytidine deaminase (AID) in MLN B cells. MLN Tfh frequency was markedly enhanced by chitosan-DNA, and was associated with VP1-specific IgA titer. 24 h after immunization, intranasal chitosan-DNA induced a recruitment of CD103+DCs into the MLN that paralleled a selective loss of CD103+DCs in the lamina propria (LP). In vivo activated MLN-derived CD103+DCs produced high levels of IL-6 and BAFF in response to chitosan-DNA, which up-regulated transmembrane activator and CAML interactor (TACI) expression on MLN B cells. Upon co-culture with IgM+B in the presence of chitosan-DNA, MLN CD103+DCs induced IgA production in a T-dependent manner; and this IgA-promoting effect of CD103+DC was blocked by targeting TACI and, to a lower extent, by blocking IL-6. MLN CD103+DCs displayed an enhanced capacity to induce an enhanced CD4+Th17 response in vivo and in vitro, and IL-17A deficient mice had a pronounced reduction of specific intestinal IgA following immunization. Taken together, mesenteric CD103+DCs are indispensable for the adjuvant activity of chitosan in enhancing DNA vaccine-specific IgA switching in gut through activating BAFF-TACI and IL-6-IL-6R signaling, and through inducing Th17/Tfh differentiation in the MLN.

Intranasal Vaccination with Mannosylated Chitosan Formulated DNA Vaccine Enables Robust IgA and Cellular Response Induction in the Lungs of Mice and Improves Protection against Pulmonary Mycobacterial Challenge.

Induction of specific humoral and cellular immunity in the lung airways is proposed to be critical for vaccine protection against Mycobacterium tuberculosis (M. tb). To facilitate airway delivery and antigen targeting to the antigen presenting cells in the alveoli, we employed mannosylated chitosan (MCS) to formulate a multi-T-epitope DNA vaccine, pPES, as an intranasal TB vaccine. MCS-DNA nanoparticles appeared spherical with the average particle sizes as 400 nm. HSP65-specific bronchoalveolar lavage fluid SIgA level was significantly elevated by 4 doses of MCS-pPES intranasal immunization as compared to chitosan (CS)-DNA and BCG vaccine. I.n. immunization with MCS-DNA induced a modest peptide-specific Th1(IFN-γ, TNF-α, and IL-2) response in the spleen, while a potent poly-functional CD4+ T response that largely produced TNF-α and IFN-γ, as well as IL-2 in the lung, qualitatively better than that induced by CS-DNA and BCG vaccination. Such response by i.n. immunization with MCS-DNA provided improved protection in the lung against airway Mycobacterial bovis BCG challenge over i.n. CS-DNA and DNA, that is comparable to protection achieved by s.c. BCG vaccination. This enhanced protection was correlated with much greater accessibility of DNA particles to the alveolar macrophages in the lung mediated by man-chitosan. Thus, man-chitosan TB vaccine represents a promising vaccine platform capable of eliciting robust multi-functional T response in the lung mucus and achieving enhanced mucosal immune protection against pulmonary TB.

Effect of higher-order aberrations and intraocular scatter on contrast sensitivity measured with a single instrument.

Higher-order aberrations (HOAs) and intraocular scatter lead to the degradation of image quality on the retina, and consequently deteriorate subjective visual performance. In this article, we modified an adaptive optics double-pass system to combine objective and subjective visual testing capabilities. Employing the modified DP system, we investigated the effects of HOAs and intraocular scatter on contrast sensitivity. Contrast sensitivity measurements were performed with HOAs either retained or corrected by adaptive optics, and with scatter either remaining at the natural eye-induced level or further enhanced by a set of three different scatter filters. Contrast sensitivity was found to be worse when HOAs were uncorrected or scatter increased. Quantitative analysis indicated that the joint effect of HOAs and scatter on contrast sensitivity was not a simple summation of each contributing factor, suggesting a potential compensatory mechanism between HOAs and intraocular scatter on contrast sensitivity.

Deblurring adaptive optics retinal images using deep convolutional neural networks.

The adaptive optics (AO) can be used to compensate for ocular aberrations to achieve near diffraction limited high-resolution retinal images. However, many factors such as the limited aberration measurement and correction accuracy with AO, intraocular scatter, imaging noise and so on will degrade the quality of retinal images. Image post processing is an indispensable and economical method to make up for the limitation of AO retinal imaging procedure. In this paper, we proposed a deep learning method to restore the degraded retinal images for the first time. The method directly learned an end-to-end mapping between the blurred and restored retinal images. The mapping was represented as a deep convolutional neural network that was trained to output high-quality images directly from blurry inputs without any preprocessing. This network was validated on synthetically generated retinal images as well as real AO retinal images. The assessment of the restored retinal images demonstrated that the image quality had been significantly improved.

Quantifying intraocular scatter with near diffraction-limited double-pass point spread function.

Measurement of the double-pass (DP) point-spread function (PSF) can provide an objective and non-invasive method for estimating intraocular scatter in the human eye. The objective scatter index (OSI), which is calculated from the DP PSF images, is commonly used to quantify intraocular scatter. In this article, we simulated the effect of higher-order ocular aberrations on OSI, and the results showed that higher-order ocular aberrations had a significant influence on OSI. Then we developed an adaptive optics DP PSF measurement system (AO-DPPMS) which was capable of correcting ocular aberrations up to eighth-order radial Zernike modes over a 6.0-mm pupil. Employing this system, we obtained DP PSF images of four subjects at the fovea. OSI values with aberrations corrected up to 2nd, 5th and 8th Zernike order were calculated respectively, from the DP PSF images of the four subjects. The experimental results were consistent with the simulation, suggesting that it is necessary to compensate for the higher-order ocular aberrations for accurate intraocular scatter estimation.

[Research on Residual Aberrations Correction with Adaptive Optics Technique in Patients Undergoing Orthokeratology].

We conducted this study to explore the influence of the ocular residual aberrations changes on contrast sensitivity(CS)function in eyes undergoing orthokeratology using adaptive optics technique.Nineteen subjects' nineteen eyes were included in this study.The subjects were between 12 and 20years(14.27±2.23years)of age.An adaptive optics(AO)system was adopted to measure and compensate the residual aberrations through a 4-mm artificial pupil,and at the same time the contrast sensitivities were measured at five spatial frequencies(2,4,8,16,and 32 cycles per degree).The CS measurements with and without AO correction were completed.The sequence of the measurements with and without AO correction was randomly arranged without informing the observers.A two-interval forced-choice procedure was used for the CS measurements.The paired t-test was used to compare the contrast sensitivity with and without AO correction at each spatial frequency.The results revealed that the AO system decreased the mean total root mean square(RMS)from 0.356µm to 0.160µm(t=10.517,P<0.001),and the mean total higher-order RMS from 0.246µm to 0.095µm(t=10.113,P<0.001).The difference in log contrast sensitivity with and without AO correction was significant only at 8cpd(t=-2.51,P=0.02).Thereby we concluded that correcting the ocular residual aberrations using adaptive optics technique could improve the contrast sensitivity function at intermediate spatial frequency in patients undergoing orthokeratology.

Effects of higher-order aberration correction on stereopsis at different viewing durations.

To better understand how the eye's optics affects stereopsis, we measured stereoacuity before and after higher-order aberration (HOA) correction with a binocular adaptive optics visual simulator. The HOAs were corrected either binocularly or monocularly in the better eye (the eye with better contrast sensitivity). A two-line stereo pattern served as the visual stimulus. Stereo thresholds at different viewing durations were obtained with the psychophysical method of constant stimuli. Binocular HOA correction led to significant improvement in stereoacuity. However, better eye HOA correction could bring either a bad degradation or a slight improvement in stereoacuity. As viewing duration increased, the stereo benefit approached the level of 1.0 for both binocular and better eye correction, suggesting that long viewing durations might weaken the effects of the eye's optical quality on stereopsis.

Adaptive optics vision simulation and perceptual learning system based on a 35-element bimorph deformable mirror.

An adaptive optics visual simulation combined with a perceptual learning (PL) system based on a 35-element bimorph deformable mirror (DM) was established. The larger stroke and smaller size of the bimorph DM made the system have larger aberration correction or superposition ability and be more compact. By simply modifying the control matrix or the reference matrix, select correction or superposition of aberrations was realized in real time similar to a conventional adaptive optics closed-loop correction. PL function was first integrated in addition to conventional adaptive optics visual simulation. PL training undertaken with high-order aberrations correction obviously improved the visual function of adult anisometropic amblyopia. The preliminary application of high-order aberrations correction with PL training on amblyopia treatment was being validated with a large scale population, which might have great potential in amblyopia treatment and visual performance maintenance.

Immature visual neural system in children reflected by contrast sensitivity with adaptive optics correction.

This study aimed to explore the neural development status of the visual system of children (around 8 years old) using contrast sensitivity. We achieved this by eliminating the influence of higher order aberrations (HOAs) with adaptive optics correction. We measured HOAs, modulation transfer functions (MTFs) and contrast sensitivity functions (CSFs) of six children and five adults with both corrected and uncorrected HOAs. We found that when HOAs were corrected, children and adults both showed improvements in MTF and CSF. However, the CSF of children was still lower than the adult level, indicating the difference in contrast sensitivity between groups cannot be explained by differences in optical factors. Further study showed that the difference between the groups also could not be explained by differences in non-visual factors. With these results we concluded that the neural systems underlying vision in children of around 8 years old are still immature in contrast sensitivity.