Natural Killer Cells Degenerate Intact Sensory Afferents following Nerve Injury.

Sensory axons degenerate following separation from their cell body, but partial injury to peripheral nerves may leave the integrity of damaged axons preserved. We show that an endogenous ligand for the natural killer (NK) cell receptor NKG2D, Retinoic Acid Early 1 (RAE1), is re-expressed in adult dorsal root ganglion neurons following peripheral nerve injury, triggering selective degeneration of injured axons. Infiltration of cytotoxic NK cells into the sciatic nerve by extravasation occurs within 3 days following crush injury. Using a combination of genetic cell ablation and cytokine-antibody complex stimulation, we show that NK cell function correlates with loss of sensation due to degeneration of injured afferents and reduced incidence of post-injury hypersensitivity. This neuro-immune mechanism of selective NK cell-mediated degeneration of damaged but intact sensory axons complements Wallerian degeneration and suggests the therapeutic potential of modulating NK cell function to resolve painful neuropathy through the clearance of partially damaged nerves.

A tryptophan-based assay method to search regulatory compounds for transcriptionally controlled tumor protein.

Transcriptionally controlled tumor protein (TCTP) is a highly conserved protein performing a large number of cellular functions by binding with various partner proteins. The importance of its roles in many diseases requires an assay method to find regulatory compounds. However, the molecular characteristics of TCTP made it difficult to search for chemicals interacting with it. In this study, a tryptophan-based assay method was designed and Y151W mutant TCTP was constructed to search binding chemicals. Since there is no tryptophan in the native sequence of TCTP, the incorporation of tryptophan in the Y151W mutant was very effective to establish the method. A flavonoid library was employed to the assay with the method. With the native and Y151W mutant TCTPs, three flavonoids such as morin, myricetin and isobavachalcone have been found to interact with TCTP. Combined with native gel electrophoresis, the binding region of isobavachalcone was suggested to be the flexible loop of TCTP. This approach can be easily applicable to find binding compounds of proteins with similar molecular characteristics of TCTP.

Fatal outcome of severe fever with thrombocytopenia syndrome (SFTS) and severe and critical COVID-19 is associated with the hyperproduction of IL-10 and IL-6 and the low production of TGF-ß.

Severe fever with thrombocytopenia syndrome virus (SFTSV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can cause the hyperproduction of inflammatory cytokines, which have pathological effects in patient including severe or fatal cytokine storms. To characterize the effect of SFTSV and SARS-CoV-2 infection on the production of cytokines in severe fever with thrombocytopenia syndrome (SFTS) and COVID-19 patients, we performed an analysis of cytokines in SFTS and COVID-19 patients and also investigated the role of interleukin-10 (IL-10) in vitro studies: lipopolysaccharide-induced THP-1-derived macrophages, SFTSV infection of THP-1 cells, and SARS-CoV-2 infection of THP-1 cells. In this study, we found that levels of both IL-10 and IL-6 were significantly elevated, the level of transforming growth factor-ß (TGF-ß) was significantly decreased and IL-10 was elevated earlier than IL-6 in severe and critical COVID-19 and fatal SFTS patients, and inhibition of IL-10 signaling decreased the production of IL-6 and elevated that of TGF-ß. Therefore, the hyperproduction of IL-10 and IL-6 and the low production of TGF-ß have been linked to cytokine storm-induced mortality in fatal SFTS and severe and critically ill COVID-19 patients and that IL-10 can play an important role in the host immune response to severe and critical SARS-CoV-2 and fatal SFTSV infection.

Anti-acne activity of carnitine salicylate and magnolol through the regulation of exfoliation, lipogenesis, bacterial growth and inflammation.

BACKGROUND: Salicylic acid has been used as an anti-acne agent with its comedolytic property and antimicrobial activity. However, there is a limit to use for leave-on cosmetics because of the transient skin irritation and low efficacy at neutral pH condition. We prepared a salicylic acid-based ionic pair with L -carnitine (we named, IP-BHA) overcoming the limitation of salicylic acid. We examined the effect of IP-BHA as well as the combination effect with magnolol, a bioactive organic lignan, in order to clarify their efficacy as anti-acne agents. METHODS: After verifying the structure of IP-BHA, we confirmed anti-acne activities including the regulation of exfoliation, lipogenesis, bacterial growth, and inflammation with IP-BHA and/or magnolol. RESULTS: The antibacterial activity of IP-BHA and magnolol was evaluated by determining the minimum antibacterial inhibitory concentration. Magnolol showed strong activity against Cutibacterium acnes, which was better than a medical antibiotic acne drug, clindamycin. The combined application with IP-BHA was more effective in antibacterial activity by 2.5 times. It was confirmed that testosterone-induced lipogenesis was significantly inhibited by treatment with IP-BHA and magnolol, while single treatment had no significant inhibitory effect. Interestingly, MMP-1 and VEGF were induced by C. acnes lysate in human keratinocytes. We found that these inflammatory molecules were completely inhibited by combined application of IP-BHA and magnolol. Through ex vivo test, the dose-dependent exfoliation effect of IP-BHA was confirmed at pH 5.5, and the synergic exfoliation effect was shown in the combined application of IP-BHA and magnolol. When topically applied, the emulsion containing IP-BHA and magnolol relieved the sodium dodecyl sulfate-induced erythema and improved inflamed acne with papule and pustule. CONCLUSION: Our data demonstrate that the ionic paired salicylic acid with L -carnitine can overcome the limitations of salicylic acid at low concentration and natural skin pH. Based on the dual administration effects, we suggest that IP-BHA and magnolol may be the potential agent for acne by improving inflammatory skin condition.

Coinfection of Severe Fever With Thrombocytopenia Syndrome Virus and Coxiella burnetii in Developmental Stage of Hard Ticks in Subtropical Region of Korea.

BACKGROUND: Severe fever with thrombocytopenia syndrome virus (SFTSV) is transmitted through tick bites. Ticks are potential vectors for the bacterium Coxiella burnetii that causes Query fever. Here, we analyzed SFTSV and C. burnetii co-infection rates in ticks in rural areas of Jeju Island, South Korea. METHODS: Free ticks were collected from the natural environment of the island between 2016 and 2019, and SFTSV RNA was extracted. Additionally, ribosomal RNA gene sequencing was used to identify Coxiella species. RESULTS: Haemaphysalis longicornis was the most common tick species followed by H. flava. Tick number gradually increased from April, peaked in August, and was lowest in March. Of all the collected ticks, 82.6% (2,851/3,458) were nymphs, 17.9% (639/3,458) adults, and 0.1% (4/3,458) larvae. SFTSV-infected ticks comprised 12.6% of all ticks; their numbers were the lowest in November-December, increased from January, and were mostly identified in the adult stage during June-August. C. burnetii infections were detected in 4.4% of the SFTSV-infected H. longicornis ticks. C. burnetii co-infection was mainly observed in the nymph stage of H. longicornis, with the highest infection rate in January, followed by December and November. CONCLUSION: Our findings suggest that Jeju Island has a high SFTSV and potential C. burnetii infection in ticks. This study provides important insights regarding SFTS and Q fever risk to humans in South Korea.

Efficacy and Safety of Epidermidibacterium Keratini EPI-7 Derived Postbiotics in Skin Aging: A Prospective Clinical Study.

The present study investigated the effect of topical application of Epidermidibacterium Keratini (EPI-7) ferment filtrate, which is a postbiotic product of a novel actinobacteria, on skin aging, by performing a prospective randomized split-face clinical study on Asian woman participants. The investigators measured skin biophysical parameters, including skin barrier function, elasticity, and dermal density, and revealed that the application of the EPI-7 ferment filtrate-including test product resulted in significantly higher improvements in barrier function, skin elasticity, and dermal density compared to the placebo group. This study also investigated the influence of EPI-7 ferment filtrate on skin microbiome diversity to access its potential beneficial effects and safety. EPI-7 ferment filtrate increased the abundance of commensal microbes belonging to Cutibacterium, Staphylococcus, Corynebacterium, Streptococcus, Lawsonella, Clostridium, Rothia, Lactobacillus, and Prevotella. The abundance of Cutibacterium was significantly increased along with significant changes in Clostridium and Prevotella abundance. Therefore, EPI-7 postbiotics, which contain the metabolite called orotic acid, ameliorate the skin microbiota linked with the aging phenotype of the skin. This study provides preliminary evidence that postbiotic therapy may affect the signs of skin aging and microbial diversity. To confirm the positive effect of EPI-7 postbiotics and microbial interaction, additional clinical investigations and functional analyses are required.

Inhibition of d-glycero-ß-d-manno-heptose 1-phosphate adenylyltransferase from Burkholderia pseudomallei by epigallocatechin gallate and myricetin.

Flavonoids play beneficial roles in various human diseases. In this study, a flavonoid library was employed to probe inhibitors of d-glycero-ß-d-manno-heptose-1-phosphate adenylyltransferase from Burkholderia pseudomallei (BpHldC) and two flavonoids, epigallocatechin gallate (EGCG) and myricetin, have been discovered. BpHldC is one of the essential enzymes in the ADP-l-glycero-ß-d-manno-heptose biosynthesis pathway constructing lipopolysaccharide of B. pseudomallei. Enzyme kinetics study showed that two flavonoids work through different mechanisms to block the catalytic activity of BpHldC. Among them, a docking study of EGCG was performed and the binding mode could explain its competitive inhibitory mode for both ATP and ßG1P. Analyses with EGCG homologs could reveal the important functional moieties, too. This study is the first example of uncovering the inhibitory activity of flavonoids against the ADP-l-glycero-ß-d-manno-heptose biosynthesis pathway and especially targeting HldC. Since there are no therapeutic agents and vaccines available against melioidosis, EGCG and myricetin can be used as templates to develop antibiotics over B. pseudomallei.

Stepwise oxidations play key roles in the structural and functional regulations of DJ-1.

DJ-1 is known to play neuroprotective roles by eliminating reactive oxygen species (ROS) as an antioxidant protein. However, the molecular mechanism of DJ-1 function has not been well elucidated. This study explored the structural and functional changes of DJ-1 in response to oxidative stress. Human DJ-1 has three cysteine residues (Cys46, Cys53 and Cys106). We found that, in addition to Cys106, Cys46 is the most reactive cysteine residue in DJ-1, which was identified employing an NPSB-B chemical probe (Ctag) that selectively reacts with redox-sensitive cysteine sulfhydryl. Peroxidatic Cys46 readily formed an intra-disulfide bond with adjacent resolving Cys53, which was identified with nanoUPLC-ESI-q-TOF tandem mass spectrometry (MS/MS) employing DBond algorithm under the non-reducing condition. Mutants (C46A and C53A), not forming Cys46-Cys53 disulfide cross-linking, increased oxidation of Cys106 to sulfinic and sulfonic acids. Furthermore, we found that DJ-1 C46A mutant has distorted unstable structure identified by biochemical assay and employing hydrogen/deuterium exchange-mass spectrometry (HDX-MS) analysis. All three Cys mutants lost antioxidant activities in SN4741 cell, a dopaminergic neuronal cell, unlike WT DJ-1. These findings suggest that all three Cys residues including Cys46-Cys53 disulfide cross-linking are required for maintaining the structural integrity, the regulation process and cellular function as an antioxidant protein. These studies broaden the understanding of regulatory mechanisms of DJ-1 that operate under oxidative conditions.

Implementation of a Prediabetes Risk Test for an Underserved Population in a Federally Qualified Health Center.

Consistent screening for prediabetes is imperative to ensure early detection and timely intervention to prevent progression to diabetes. Adopting a standardized approach such as a screening tool can streamline the screening process. This articles describes a quality improvement project conducted at a federally qualified health center to assess whether implementation of the Prediabetes Risk Test improved early detection of prediabetes in an underserved population. Use of the risk test was found to improve detection of prediabetes in this population.

Dimerization Tendency of 3CLpros of Human Coronaviruses Based on the X-ray Crystal Structure of the Catalytic Domain of SARS-CoV-2 3CLpro.

3CLpro of SARS-CoV-2 is a promising target for developing anti-COVID19 agents. In order to evaluate the catalytic activity of 3CLpros according to the presence or absence of the dimerization domain, two forms had been purified and tested. Enzyme kinetic studies with a FRET method revealed that the catalytic domain alone presents enzymatic activity, despite it being approximately 8.6 times less than that in the full domain. The catalytic domain was crystallized and its X-ray crystal structure has been determined to 2.3 Å resolution. There are four protomers in the asymmetric unit. Intriguingly, they were packed as a dimer though the dimerization domain was absent. The RMSD of superimposed two catalytic domains was 0.190 for 182 Cα atoms. A part of the long hinge loop (LH-loop) from Gln189 to Asp197 was not built in the model due to its flexibility. The crystal structure indicates that the decreased proteolytic activity of the catalytic domain was due to the incomplete construction of the substrate binding part built by the LH-loop. A structural survey with other 3CLpros showed that SARS-CoV families do not have interactions between DM-loop due to the conformational difference at the last turn of helix α7 compared with others. Therefore, we can conclude that the monomeric form contains nascent enzyme activity and that its efficiency increases by dimerization. This new insight may contribute to understanding the behavior of SARS-CoV-2 3CLpro and thus be useful in developing anti-COVID-19 agents.

A Study of Drug Repurposing to Identify SARS-CoV-2 Main Protease (3CLpro) Inhibitors.

The outbreak of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) wreaked havoc all over the world. Although vaccines for the disease have recently become available and started to be administered to the population in various countries, there is still a strong and urgent need for treatments to cure COVID-19. One of the safest and fastest strategies is represented by drug repurposing (DRPx). In this study, thirty compounds with known safety profiles were identified from a chemical library of Phase II-and-up compounds through a combination of SOM Biotech's Artificial Intelligence (AI) technology, SOMAIPRO, and in silico docking calculations with third-party software. The selected compounds were then tested in vitro for inhibitory activity against SARS-CoV-2 main protease (3CLpro or Mpro). Of the thirty compounds, three (cynarine, eravacycline, and prexasertib) displayed strong inhibitory activity against SARS-CoV-2 3CLpro. VeroE6 cells infected with SARS-CoV-2 were used to find the cell protection capability of each candidate. Among the three compounds, only eravacycline showed potential antiviral activities with no significant cytotoxicity. A further study is planned for pre-clinical trials.

Reliability and Validity of the Korean Child Sensory Profile-2.

IMPORTANCE: The Korean Child Sensory Profile-2 (K-CSP-2) is a tool for assessing sensory processing that was recently culturally adapted for use with Korean children. OBJECTIVE: To investigate the test-retest and interrater reliability and the convergent and discriminant validity of the K-CSP-2. DESIGN: Cross-sectional study. SETTING: Community settings in South Korea. PARTICIPANTS: Caregivers of 102 children with autism spectrum disorder (ASD) and 156 typically developing (TD) children ages 3-14 yr. OUTCOMES AND MEASURES: The K-CSP-2 was tested for reliability and validity using the Korean version of the Sensory Profile (K-SP) and the Korean Behavior Assessment System for Children-2 (K-BASC-2). RESULTS: The K-CSP-2 demonstrated good test-retest and interrater reliability. The K-CSP-2 was correlated with the K-SP and the K-BASC-2. Children with ASD had higher K-CSP-2 scores than TD children. The discriminant analysis classified children with ASD and TD children with an overall accuracy of 89%. CONCLUSIONS AND RELEVANCE: The K-CSP-2 can be used to assess the sensory processing of Korean children consistently across time and raters. The instrument maintains the quadrant factors of the K-SP and relates to adaptive and maladaptive behaviors. The K-CSP-2 can distinguish children with ASD from TD children. What This Article Adds: Korean occupational therapy practitioners can use the K-CSP-2 to identify sensory processing patterns and to support the evaluation of children with ASD.

Are occupational and environmental noises associated with periodontitis? Evidence from a Korean representative cross-sectional study.

BACKGROUND: Evidences have shown that noise could be a risk factor for cardiovascular and metabolic diseases. Since periodontitis and CVD are characterized by inflammation, it is reasonable to doubt that occupational/environmental noise is a risk factor for periodontitis. The aim of this study was to examine the relationship between occupational/environmental noise and periodontitis in a nationally representative sample of Korean adults. METHODS: This cross-sectional study used data from the 7th Korean National Health and Nutrition Examination Survey. The study sample included 8327 adults aged 40 to 80 years old. Noise exposure and the duration of the exposure were assessed with self-report questionnaires. The dependent variable was periodontitis. Age, gender, place of residence, income, marital status, smoking, frequency of daily tooth brushing, recent dental checkup, and diabetes were included as covariates. Logistic regression analyses estimated the association between noise exposure and periodontitis. RESULTS: Those who were exposed to environmental noise during their lifetime had an increased prevalence of severe periodontitis (odds ratio [OR] 1.88; 95% confidence interval [CI] 1.05 to 3.40), and this association was strengthened as the duration of the environmental noise exposure was longer (OR of > 120 months 2.35 and OR of ≤120 months 1.49). There was a combined relationship for severe periodontitis between occupational and environmental noise exposure (OR of both exposures 2.62, OR of occupational exposure only 1.12, and OR of environmental exposure only 1.57). CONCLUSION: Our study shows that noise exposure is associated with periodontitis, and the association was higher in the synergism between occupational and environmental interaction.

A study of inhibitors of d-glycero-ß-d-manno-heptose-1-phosphate adenylyltransferase from Burkholderia pseudomallei as a potential antibiotic target.

d-Glycero-ß-d-manno-heptose-1-phosphate adenylyltransferase from Burkholderia pseudomallei (BpHldC) is the fourth enzyme in the ADP-l-glycero-ß-d-manno-heptose biosynthesis pathway producing a lipopolysaccharide core. Therefore, BpHldC is an anti-melioidosis target. Three ChemBridge compounds purchased from ChemBridge Corporation (San Diego, CA) were found to have an effective inhibitory activity on BpHldC. Interestingly, ChemBridge 7929959 was the most effective compound due to the presence of the terminal benzyl group. The enzyme kinetic study revealed that most of them show mixed type inhibitory modes against ATP and ßG1P. The induced-fit docking indicated that the medium affinity of ChemBridge 7929959 is originated from its benzyl group occupying the substrate-binding pocket of BpHldC. The inhibitory role of terminal aromatic groups was proven with ChemBridge 7570508. Combined with the previous study, ChemBridge 7929959 is found to work as a dual inhibitor against both HldC and HddC. Therefore, three ChemBridge compounds can be developed as a potent anti-melioidosis agent with a novel inhibitory concept.

A triple-targeting inhibitory activity of Rose Bengal on polysaccharide biosynthesis of Burkholderia pseudomallei.

Sugar nucleotidyltransferases (SNTs) participate in various biosynthesis pathways constructing polysaccharides in Gram-negative bacteria. In this study, a triple-targeting inhibitory activity of Rose Bengal against SNTs such as d-glycero-α-d-manno-heptose-1-phosphate guanylyltransferase (HddC), d-glycero-ß-d-manno-heptose-1-phosphate adenylyltransferase (HldC), and 3-deoxy-d-manno-oct-2-ulosonic acid cytidylyltransferase (KdsB) from Burkholderia pseudomallei is provided. Rose Bengal effectively suppresses the nucleotidyltransferase activity of the three SNTs, and its IC50 values are 10.42, 0.76, and 5.31 µM, respectively. Interestingly, Rose Bengal inhibits the three enzymes regardless of their primary, secondary, tertiary, and quaternary structural differences. The experimental results indicate that Rose Bengal possesses the plasticity to shape its conformation suitable to interact with the three SNTs. As HddC functions in the formation of capsular polysaccharides and HldC and KdsB produce building blocks to constitute the inner core of lipopolysaccharide, Rose Bengal is a potential candidate to design antibiotics in a new category. In particular, it can be developed as a specific antimelioidosis agent. As the mortality rate of the infected people caused by B. pseudomallei is quite high, there is an urgent need for specific antimelioidosis agents. Therefore, a further study is being carried out with derivatives of Rose Bengal.

Inhibition of African swine fever virus protease by myricetin and myricitrin.

African swine fever (ASF) caused by the ASF virus (ASFV) is the most hazardous swine disease. Since a huge number of pigs have been slaughtered to avoid a pandemic spread, intense studies on the disease should be followed quickly. Recent studies reported that flavonoids have various antiviral activity including ASFV. In this report, ASFV protease was selected as an antiviral target protein to cope with ASF. With a FRET (Fluorescence resonance energy transfer) method, ASFV protease was assayed with a flavonoid library which was composed of sixty-five derivatives classified based on ten different scaffolds. Of these, the flavonols scaffold contains a potential anti-ASFV protease activity. The most prominent flavonol was myricetin with IC50 of 8.4 µM. Its derivative, myricitrin, with the rhamnoside moiety was also showed the profound inhibitory effect on ASFV protease. These two flavonols apparently provide a way to develop anti-ASFV agents based on their scaffold.

A study of Rose Bengal against a 2-keto-3-deoxy-d-manno-octulosonate cytidylyltransferase as an antibiotic candidate.

Frequent occurrences of multi-drug resistance of pathogenic Gram-negative bacteria threaten human beings. The CMP-2-keto-3-deoxy-d-manno-octulosonic acid biosynthesis pathway is one of the new targets for antibiotic design. 2-Keto-3-deoxy-d-manno-octulosonate cytidylyltransferase (KdsB) is the key enzyme in this pathway. KdsB proteins from Burkholderia pseudomallei (Bp), B. thailandensis (Bt), Pseudomonas aeruginosa (Pa), and Chlamydia psittaci (Cp) have been assayed to find inhibitors. Interestingly, Rose Bengal (4,5,6,7-tetrachloro-2',4',5',7'-tetraiodofluorescein) was turned out to be an inhibitor of three KdsBs (BpKdsB, BtKdsB, and PaKdsB) with promising IC50 values and increased thermostability. The inhibitory enzyme kinetics of Rose Bengal revealed that it is competitive with 2-keto-3-deoxy-manno-octulosonic acid (KDO) but non-competitive against cytidine 5'-triphosphate (CTP). Induced-fit docking analysis of PaKdsB revealed that Arg160 and Arg185 together with other interactions in the substrate binding site seemed to play an important role in binding with Rose Bengal. We suggest that Rose Bengal can be used as the scaffold to develop potential antibiotics.

Inhibition of SARS-CoV 3CL protease by flavonoids.

There were severe panics caused by Severe Acute Respiratory Syndrome (SARS) and Middle-East Respiratory Syndrome-Coronavirus. Therefore, researches targeting these viruses have been required. Coronaviruses (CoVs) have been rising targets of some flavonoids. The antiviral activity of some flavonoids against CoVs is presumed directly caused by inhibiting 3C-like protease (3CLpro). Here, we applied a flavonoid library to systematically probe inhibitory compounds against SARS-CoV 3CLpro. Herbacetin, rhoifolin and pectolinarin were found to efficiently block the enzymatic activity of SARS-CoV 3CLpro. The interaction of the three flavonoids was confirmed using a tryptophan-based fluorescence method, too. An induced-fit docking analysis indicated that S1, S2 and S3' sites are involved in binding with flavonoids. The comparison with previous studies showed that Triton X-100 played a critical role in objecting false positive or overestimated inhibitory activity of flavonoids. With the systematic analysis, the three flavonoids are suggested to be templates to design functionally improved inhibitors.

Flavonoids with inhibitory activity against SARS-CoV-2 3CLpro.

Coronavirus disease 2019 (COVID-19) has been a pandemic disease of which the termination is not yet predictable. Currently, researches to develop vaccines and treatments is going on globally to cope with this disastrous disease. Main protease (3CLpro) from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is one of the good targets to find antiviral agents before vaccines are available. Some flavonoids are known to inhibit 3CLpro from SARS-CoV which causes SARS. Since their sequence identity is 96%, a similar approach was performed with a flavonoid library. Baicalin, herbacetin, and pectolinarin have been discovered to block the proteolytic activity of SARS-CoV-2 3CLpro. An in silico docking study showed that the binding modes of herbacetin and pectolinarin are similar to those obtained from the catalytic domain of SARS-CoV 3CLpro. However, their binding affinities are different due to the usage of whole SARS-CoV-2 3CLpro in this study. Baicalin showed an effective inhibitory activity against SARS-CoV-2 3CLpro and its docking mode is different from those of herbacetin and pectolinarin. This study suggests important scaffolds to design 3CLpro inhibitors to develop antiviral agents or health-foods and dietary supplements to cope with SARS-CoV-2.

Can we study 3D grid codes non-invasively in the human brain? Methodological considerations and fMRI findings.

Recent human functional magnetic resonance imaging (fMRI) and animal electrophysiology studies suggest that grid cells in entorhinal cortex are an efficient neural mechanism for encoding knowledge about the world, not only for spatial location but also for more abstract cognitive information. The world, be it physical or abstract, is often high-dimensional, but grid cells have been mainly studied on a simple two-dimensional (2D) plane. Recent theoretical studies have proposed how grid cells encode three-dimensional (3D) physical space, but it is unknown whether grid codes can be examined non-invasively in humans. Here, we investigated whether it was feasible to test different 3D grid models using fMRI based on the direction-modulated property of grid signals. In doing so, we developed interactive software to help researchers visualize 3D grid fields and predict grid activity in 3D as a function of movement directions. We found that a direction-modulated grid analysis was sensitive to one type of 3D grid model - a face-centred cubic (FCC) lattice model. As a proof of concept, we searched for 3D grid-like signals in human entorhinal cortex using a novel 3D virtual reality paradigm and a new fMRI analysis method. We found that signals in the left entorhinal cortex were explained by the FCC model. This is preliminary evidence for 3D grid codes in the human brain, notwithstanding the inherent methodological limitations of fMRI. We believe that our findings and software serve as a useful initial stepping-stone for studying grid cells in realistic 3D worlds and also, potentially, for interrogating abstract high-dimensional cognitive processes.