Enhancing genome editing in hPSCs through dual inhibition of DNA damage response and repair pathways

Precise genome editing is crucial for establishing isogenic human disease models and ex vivo stem cell therapy from the patient-derived hPSCs. Unlike Cas9-mediated knock-in, cytosine base editor and prime editor achieve the desirable gene correction without inducing DNA double strand breaks. However, hPSCs possess highly active DNA repair pathways and are particularly susceptible to p53-dependent cell death. These unique characteristics impede the efficiency of gene editing in hPSCs. Here, we demonstrate that dual inhibition of p53-mediated cell death and distinct activation of the DNA damage repair system upon DNA damage by cytosine base editor or prime editor additively enhanced editing efficiency in hPSCs. The BE4stem system comprised of p53DD, a dominant negative p53, and three UNG inhibitor, engineered to specifically diminish base excision repair, improves cytosine base editor efficiency in hPSCs. Addition of dominant negative MLH1 to inhibit mismatch repair activity and p53DD in the conventional prime editor system also significantly enhances prime editor efficiency in hPSCs. Thus, combined inhibition of the distinct cellular cascades engaged in hPSCs upon gene editing could significantly enhance precise genome editing in these cells.

Genome-wide in-locus epitope tagging of Arabidopsis proteins using prime editors

Prime editors (PEs), which are CRISPR-Cas9 nickase (H840A)-reverse transcriptase fusion proteins programmed with prime editing guide RNAs (pegRNAs), can not only edit bases but also install transversions, insertions, or deletions without both donor DNA and double-strand breaks at the target DNA. As the demand for in-locus tagging is increasing, to reflect gene expression dynamics influenced by endogenous genomic contexts, we demonstrated that PEs can be used to introduce the hemagglutinin (HA) epitope tag to a target gene locus, enabling molecular and biochemical studies using in-locus tagged plants. To promote genome-wide in-locus tagging, we also implemented a publicly available database that designs pegRNAs for in-locus tagging of all the Arabidopsis genes. [BMB Reports 2024; 57(1): 66-70].

Direct measurement of engineered cancer mutations and their transcriptional phenotypes in single cells

Genome sequencing studies have identified numerous cancer mutations across a wide spectrum of tumor types, but determining the phenotypic consequence of these mutations remains a challenge. Here, we developed a high-throughput, multiplexed single-cell technology called TISCC-seq to engineer predesignated mutations in cells using CRISPR base editors, directly delineate their genotype among individual cells and determine each mutation's transcriptional phenotype. Long-read sequencing of the target gene's transcript identifies the engineered mutations, and the transcriptome profile from the same set of cells is simultaneously analyzed by short-read sequencing. Through integration, we determine the mutations' genotype and expression phenotype at single-cell resolution. Using cell lines, we engineer and evaluate the impact of >100 TP53 mutations on gene expression. Based on the single-cell gene expression, we classify the mutations as having a functionally significant phenotype.

Extru-seq: a method for predicting genome-wide Cas9 off-target sites with advantages of both cell-based and in vitro approaches

We present a novel genome-wide off-target prediction method named Extru-seq and compare it with cell-based (GUIDE-seq), in vitro (Digenome-seq), and in silico methods using promiscuous guide RNAs with large numbers of valid off-target sites. Extru-seq demonstrates a high validation rate and retention of information about the intracellular environment, both beneficial characteristics of cell-based methods. Extru-seq also shows a low miss rate and could easily be performed in clinically relevant cell types with little optimization, which are major positive features of the in vitro methods. In summary, Extru-seq shows beneficial features of cell-based and in vitro methods.

Web-Based Computational Tools for Base Editors

CRISPR-based base editors are efficient genome editing tools for use in base correction. Currently, there are various versions and types of base editors with different substitution patterns, editing windows, and protospacer adjacent motif (PAM) sequences. For the design of target sequences, consideration of off-target sequences is required. In addition, for assessment of base editing outcomes in bulk populations, the analysis of high-throughput sequencing data is required. Several web browser-based computation programs have been developed for the purpose of target design and NGS data analysis, especially for users with less computational knowledge. In this manuscript, depending on the purpose of each program, we provide an explanation of useful tools including BE-Designer for design of targets and BE-Analyzer for analysis of NGS data that were developed by our group, CRISPResso2 for analysis of NGS data developed by Luca Pinello group, DeepBaseEditor for prediction of target efficiency developed by Hyongbum Henry Kim group, and BE-Hive for prediction of target outcome developed by David Liu group.

METTL3 regulates alternative splicing of cell cycle-related genes via crosstalk between mRNA m6A modifications and splicing factors

N⁶-methyladenosine (m⁶A) modification in RNA affects various aspects of RNA metabolism and regulates gene expression. This modification is modulated by many regulatory proteins, such as m⁶A methyltransferases (writers), m⁶A demethylases (erasers), and m⁶A-binding proteins (readers). Previous studies have suggested that alterations in m⁶A regulatory proteins induce genome-wide alternative splicing in many cancer cells. However, the functional effects and molecular mechanisms of m⁶A-mediated alternative splicing have not been fully elucidated. To understand the consequences of this modification on RNA splicing in cancer cells, we performed RNA sequencing and analyzed alternative splicing patterns in METTL3-knockdown osteosarcoma U2OS cells. We detected 1,803 alternatively spliced genes in METTL3-knockdown cells compared to the controls and found that cell cycle-related genes were enriched in differentially spliced genes. A comparison of the published MeRIP-seq data for METTL14 with our RNA sequencing data revealed that 70-87% of alternatively spliced genes had an m⁶A peak near 1 kb of alternative splicing sites. Among the 19 RNA-binding proteins enriched in alternative splicing sites, as revealed by motif analysis, expression of SFPQ highly correlated with METTL3 expression in 12,839 TCGA pan-cancer patients. We also found that cell cycle-related genes were enriched in alternatively spliced genes of other cell lines with METTL3 knockdown. Taken together, we suggest that METTL3 regulates m⁶A-dependent alternative splicing, especially in cell cycle-related genes, by regulating the functions of splicing factors such as SFPQ.

High-Fidelity Cytosine Base Editing in a GC-Rich Corynebacterium glutamicum with Reduced DNA Off-Target Editing Effects

Genome editing technology is a powerful tool for programming microbial cell factories. However, rat APOBEC1-derived cytosine base editor (CBE) that converts C•G to T•A at target genes induced DNA off-targets, regardless of single-guide RNA (sgRNA) sequences. Although the high efficiencies of the bacterial CBEs have been developed, a risk of unidentified off-targets impeded genome editing for microbial cell factories. To address the issues, we demonstrate the genome engineering of Corynebacterium glutamicum as a GC-rich model industrial bacterium by generating premature termination codons (PTCs) in desired genes using high-fidelity cytosine base editors (CBEs). Through this CBE-STOP approach of introducing specific cytosine conversions, we constructed several single-gene-inactivated strains for three genes (ldh, idsA, and pyc) with high base editing efficiencies of average 95.6% (n = 45, C6 position) and the highest success rate of up to 100% for PTCs and ultimately developed a strain with five genes (ldh, actA, ackA, pqo, and pta) that were inactivated sequentially for enhancing succinate production. Although these mutant strains showed the desired phenotypes, whole-genome sequencing (WGS) data revealed that genome-wide point mutations occurred in each strain and further accumulated according to the duration of CBE plasmids. To lower the undesirable mutations, high-fidelity CBEs (pCoryne-YE1-BE3 and pCoryne-BE3-R132E) was employed for single or multiplexed genome editing in C. glutamicum, resulting in drastically reduced sgRNA-independent off-targets. Thus, we provide a CRISPR-assisted bacterial genome engineering tool with an average high efficiency of 90.5% (n = 76, C5 or C6 position) at the desired targets. IMPORTANCE Rat APOBEC1-derived cytosine base editor (CBE) that converts C•G to T•A at target genes induced DNA off-targets, regardless of single-guide RNA (sgRNA) sequences. Although the high efficiencies of bacterial CBEs have been developed, a risk of unidentified off-targets impeded genome editing for microbial cell factories. To address the issues, we identified the DNA off-targets for single and multiple genome engineering of the industrial bacterium Corynebacterium glutamicum using whole-genome sequencing. Further, we developed the high-fidelity (HF)-CBE with significantly reduced off-targets with comparable efficiency and precision. We believe that our DNA off-target analysis and the HF-CBE can promote CRISPR-assisted genome engineering over conventional gene manipulation tools by providing a markerless genetic tool without need for a foreign DNA donor.

Therapeutic base editing and prime editing of COL7A1 mutations in recessive dystrophic epidermolysis bullosa

Recessive dystrophic epidermolysis bullosa (RDEB) is a severe skin fragility disorder caused by loss-of-function mutations in the COL7A1 gene, which encodes type VII collagen (C7), a protein that functions in skin adherence. From 36 Korean RDEB patients, we identified a total of 69 pathogenic mutations (40 variants without recurrence), including point mutations (72.5%) and insertion/deletion mutations (27.5%). For fibroblasts from two patients (Pat1 and Pat2), we applied adenine base editors (ABEs) to correct the pathogenic mutation of COL7A1 or to bypass a premature stop codon in Pat1-derived primary fibroblasts. To expand the targeting scope, we also utilized prime editors (PEs) to correct the COL7A1 mutations in Pat1- and Pat2-derived fibroblasts. Ultimately, we found that transfer of edited patient-derived skin equivalents (i.e., RDEB keratinocytes and PE-corrected RDEB fibroblasts from the RDEB patient) into the skin of immunodeficient mice led to C7 deposition and anchoring fibril formation within the dermal-epidermal junction, suggesting that base editing and prime editing could be feasible strategies for ex vivo gene editing to treat RDEB.

Comprehensive analysis of prime editing outcomes in human embryonic stem cells

Prime editing is a versatile and precise genome editing technique that can directly copy desired genetic modifications into target DNA sites without the need for donor DNA. This technique holds great promise for the analysis of gene function, disease modeling, and the correction of pathogenic mutations in clinically relevant cells such as human pluripotent stem cells (hPSCs). Here, we comprehensively tested prime editing in hPSCs by generating a doxycycline-inducible prime editing platform. Prime editing successfully induced all types of nucleotide substitutions and small insertions and deletions, similar to observations in other human cell types. Moreover, we compared prime editing and base editing for correcting a disease-related mutation in induced pluripotent stem cells derived form a patient with α 1-antitrypsin (A1AT) deficiency. Finally, whole-genome sequencing showed that, unlike the cytidine deaminase domain of cytosine base editors, the reverse transcriptase domain of a prime editor does not lead to guide RNA-independent off-target mutations in the genome. Our results demonstrate that prime editing in hPSCs has great potential for complementing previously developed CRISPR genome editing tools.

In vivo gene editing via homology-independent targeted integration for adrenoleukodystrophy treatment

Adrenoleukodystrophy (ALD) is caused by various pathogenic mutations in the X-linked ABCD1 gene, which lead to metabolically abnormal accumulations of very long-chain fatty acids in many organs. However, curative treatment of ALD has not yet been achieved. To treat ALD, we applied two different gene-editing strategies, base editing and homology-independent targeted integration (HITI), in ALD patient-derived fibroblasts. Next, we performed in vivo HITI-mediated gene editing using AAV9 vectors delivered via intravenous administration in the ALD model mice. We found that the ABCD1 mRNA level was significantly increased in HITI-treated mice, and the plasma levels of C24:0-LysoPC (lysophosphatidylcholine) and C26:0-LysoPC, sensitive diagnostic markers for ALD, were significantly reduced. These results suggest that HITI-mediated mutant gene rescue could be a promising therapeutic strategy for human ALD treatment.

PE-Designer and PE-Analyzer: web-based design and analysis tools for CRISPR prime editing

Prime editing technology is capable of generating targeted insertions, deletions, and base conversions. However, the process of designing prime editing guide RNAs (pegRNAs), which contain a primer binding site and a reverse-transcription template at the 3′ end, is more complex than that for the single guide RNAs used with CRISPR nucleases or base editors. Furthermore, the assessment of high-throughput sequencing data after prime editors (PEs) have been employed should consider the unique feature of PEs; thus, pre-existing assessment tools cannot directly be adopted for PEs. Here, we present two user-friendly web-based tools for PEs, named PE-Designer and PE-Analyzer. PE-Designer, a dedicated tool for pegRNA selection, provides all possible target sequences, pegRNA extension sequences, and nicking guide RNA sequences together with useful information, and displays the results in an interactive image. PE-Analyzer, a dedicated tool for PE outcome analysis, accepts high-throughput sequencing data, summarizes mutation-related information in a table, and provides interactive graphs. PE-Analyzer was mainly written using JavaScript so that it can analyze several data sets without requiring that huge sequencing data (>100MB) be uploaded to the server, reducing analysis time and increasing personal security. PE-Designer and PE-Analyzer are freely available at http://www.rgenome.net/pe-designer/ and http://www.rgenome.net/pe-analyzer/ without a login process.

Analysis of NHEJ-Based DNA Repair after CRISPR-Mediated DNA Cleavage

Genome editing using CRISPR-Cas9 nucleases is based on the repair of the DNA double-strand break (DSB). In eukaryotic cells, DSBs are rejoined through homology-directed repair (HDR), non-homologous end joining (NHEJ) or microhomology-mediated end joining (MMEJ) pathways. Among these, it is thought that the NHEJ pathway is dominant and occurs throughout a cell cycle. NHEJ-based DSB repair is known to be error-prone; however, there are few studies that delve into it deeply in endogenous genes. Here, we quantify the degree of NHEJ-based DSB repair accuracy (termed NHEJ accuracy) in human-originated cells by incorporating exogenous DNA oligonucleotides. Through an analysis of joined sequences between the exogenous DNA and the endogenous target after DSBs occur, we determined that the average value of NHEJ accuracy is approximately 75% in maximum in HEK 293T cells. In a deep analysis, we found that NHEJ accuracy is sequence-dependent and the value at the DSB end proximal to a protospacer adjacent motif (PAM) is relatively lower than that at the DSB end distal to the PAM. In addition, we observed a negative correlation between the insertion mutation ratio and the degree of NHEJ accuracy. Our findings would broaden the understanding of Cas9-mediated genome editing.

CReVIS-Seq: A highly accurate and multiplexable method for genome-wide mapping of lentiviral integration sites

Lentiviruses have been widely used as a means of transferring exogenous DNAs into human cells to treat various genetic diseases. Lentiviral vectors are fundamentally integrated into the host genome, but their integration sites are generally unpredictable, which may increase the uncertainty for their use in therapeutics. To determine the viral integration sites in the host genome, several PCR-based methods have been developed. However, the sensitivities of the PCR-based methods are highly dependent on the primer sequences, and optimized primer design is required for individual target sites. In order to address this issue, we developed an alternative method for genome-wide mapping of viral insertion sites, named CReVIS-seq (CRISPR-enhanced Viral Integration Site Sequencing). The method is based on the sequential steps: fragmentation of genomic DNAs, in vitro circularization, cleavage of target sequence in a CRISPR guide RNA-specific manner, high-throughput sequencing of the linearized DNA fragments in an unbiased manner, and identification of viral insertion sites via sequence analysis. By design, CReVIS-seq is not affected by biases that could be introduced during the target enrichment step via PCR amplification using site specific primers. Furthermore, we found that multiplexed CReVIS-seq, using collections of different single-guide RNAs (sgRNAs), enables simultaneous identification of multiple target sites and structural variations (i.e., circularized viral genome), in both single cell clones and heterogeneous cell populations.

Web-Based Base Editing Toolkits: BE-Designer and BE-Analyzer

The CRISPR-Cas system is broadly used for genome editing because of its convenience and relatively low cost. However, the use of CRISPR nucleases to induce specific nucleotide changes in target DNA requires complex procedures and additional donor DNAs. Furthermore, CRISPR nuclease-mediated DNA cleavage at target sites frequently causes large deletions or genomic rearrangements. In contrast, base editors that consist of catalytically dead Cas9 (dCas9) or Cas9 nickase (nCas9) connected to a cytidine or a guanine deaminase can correct point mutations in the absence of additional donor DNA and without generating double-strand breaks (DSBs) in the target region. To design target sites and assess mutation ratios for cytosine and adenine base editors (CBEs and ABEs), we have developed web tools, named BE-Designer and BE-Analyzer. These tools are easy to use (such that tasks are accomplished by clicking on relevant buttons) and do not require a deep knowledge of bioinformatics.

Web-Based CRISPR Toolkits: Cas-OFFinder, Cas-Designer, and Cas-Analyzer

The CRISPR-Cas system facilitates highly efficient genome editing; thus, it has been applied in many research fields such as biological science, medicine, and gene therapy. However, CRISPR nucleases can cleave off-target sites as well as on-target sites, causing unwanted mutations. Furthermore, after CRISPR treatments are delivered into cells or organisms, it is important to estimate the resulting mutation rates and to determine the patterns of mutations, but these tasks can be difficult. To address these issues, we have developed a tool for identifying potential off-target sites (Cas-OFFinder), a tool for designing CRISPR targets (Cas-Designer), and an assessment tool (Cas-Analyzer). These programs are all implemented on our website so that researchers can easily design CRISPR guide RNAs and assess the resulting mutations by simply clicking on the appropriate buttons; no login process is required.

CRISPR-Pass: Gene Rescue of Nonsense Mutations Using Adenine Base Editors

A nonsense mutation is a substitutive mutation in a DNA sequence that causes a premature termination during translation and produces stalled proteins, resulting in dysfunction of a gene. Although it usually induces severe genetic disorders, there are no definite methods for inducing read through of premature termination codons (PTCs). Here, we present a targeted tool for bypassing PTCs, named CRISPR-pass, that uses CRISPR-mediated adenine base editors. CRISPR-pass, which should be applicable to 95.5% of clinically significant nonsense mutations in the ClinVar database, rescues protein synthesis in patient-derived fibroblasts, suggesting potential clinical utility.

Web-based design and analysis tools for CRISPR base editing

Background

As a result of its simplicity and high efficiency, the CRISPR-Cas system has been widely used as a genome editing tool. Recently, CRISPR base editors, which consist of deactivated Cas9 (dCas9) or Cas9 nickase (nCas9) linked with a cytidine or a guanine deaminase, have been developed. Base editing tools will be very useful for gene correction because they can produce highly specific DNA substitutions without the introduction of any donor DNA, but dedicated web-based tools to facilitate the use of such tools have not yet been developed.

Results

We present two web tools for base editors, named BE-Designer and BE-Analyzer. BE-Designer provides all possible base editor target sequences in a given input DNA sequence with useful information including potential off-target sites. BE-Analyzer, a tool for assessing base editing outcomes from next generation sequencing (NGS) data, provides information about mutations in a table and interactive graphs. Furthermore, because the tool runs client-side, large amounts of targeted deep sequencing data (< 1 GB) do not need to be uploaded to a server, substantially reducing running time and increasing data security. BE-Designer and BE-Analyzer can be freely accessed at http://www.rgenome.net/be-designer/ and http://www.rgenome.net/be-analyzer/, respectively.

Conclusion

We develop two useful web tools to design target sequence (BE-Designer) and to analyze NGS data from experimental results (BE-Analyzer) for CRISPR base editors.

Electronic supplementary material

The online version of this article (10.1186/s12859-018-2585-4) contains supplementary material, which is available to authorized users.

Abstract P3-06-01: Therapeutic targeting of RAGE in the tumor and tumor microenvironment inhibits breast progression and metastasis

Background: The Receptor for Advanced-Glycation End-products (RAGE) is highly expressed in various cancers and its expression is correlated with poorer outcomes in breast cancer. We have previously implicated RAGE in breast cancer, but whether RAGE drives breast cancer progression and metastasis either through tumor cell intrinsic effects, non-tumor cells of the tumor microenvironment, or both, is not fully understood. More importantly, studies are lacking that target RAGE therapeutically in cancer, and may therefore represent a novel treatment for breast cancer metastasis.

Methods: Using multiple human and murine breast cancer models we dissected the tumor intrinsic versus tumor microenvironment role of RAGE in metastasis. RAGE was targeted in tumor cells using multiple shRNAs, in non-tumor cells by global gene knockout in mice, and both by therapeutically targeting with the novel RAGE inhibitor FPS-ZM1. In vivo orthotopic models included the NSG (NOD-SCID-gamma) xenograft mouse model (with MDA-MB-231 cells; herein 231), BALBc (4T-1 and 67NR), and C57BL6 wild-type and RAGE knockout (RAGE -/-) mice (with MMTV-PyMT spontaneous breast cancer derived AT-3 cells).

Results: We first tested how RAGE impacts tumor cell intrinsic mechanisms using either RAGE shRNAs or FPS-ZM1 in 231, 4175 (231 isogenic highly metastatic cells) and 4T-1 cells. RAGE shRNA and FPS-ZM1 both decreased RAGE MAP-kinase signaling, transwell invasion and soft agar colony formation, without affecting proliferation. In vivo, RAGE shRNA knockdown in 231 cells did not affect tumor growth, but inhibited metastasis to lung and liver. RAGE shRNA knockdown in 4175 cells, decreased orthotopic tumor growth, and reduced tumor angiogenesis and tumor recruitment of leukocyte / macrophages. Furthermore, RAGE shRNA knockdown dramatically decreased metastasis of 4175 cells to lung and liver in a time and sized matched manner compared to shRNA controls. Similarly, RAGE knockdown in 4T-1 cells reduced cell invasion and colony formation, and inhibited lung metastasis from the orthotopic site in BALBc immunocompetent mice.

To test the non-tumor cell microenvironment role of RAGE, we performed syngeneic studies with orthotopically injected AT-3 cells in RAGE +/+ and RAGE -/- C57BL6 mice. RAGE -/- mice displayed striking impairment of tumor cell growth compared to RAGE +/+ mice, along with decreased MAP-kinase signaling, tumor angiogenesis and inflammatory cell recruitment.

Finally, to test the combined inhibition of RAGE in both tumor cell intrinsic and non-tumor cells of the microenvironment, we performed in vivo treatment of 4175 tumors with FPS-ZM1 (1mg/kg, twice per week). Compared to vehicle, FPS-ZM1 inhibited primary tumor growth, inhibited tumor angiogenesis and inflammatory cell recruitment, and most importantly prevented metastasis to lung and liver.

Conclusion: These data clearly demonstrate a role for RAGE in breast cancer progression and metastasis through distinct effects in the tumor cell and non-tumor cells of the tumor microenvironment. Furthermore, our data from drug inhibitor studies highlight the combined targeting of RAGE in the tumor and tumor microenvironment, and as a viable therapeutic means for breast and other metastatic cancers.

Citation Format: Kwak T, Drews-Elger K, Ergonul A, Braley A, Hwang GH, El-Ashry D, Slingerland JM, Lippman ME, Hudson BI. Therapeutic targeting of RAGE in the tumor and tumor microenvironment inhibits breast progression and metastasis [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P3-06-01.

Assessment of the effect of methionine supplementation and inclusion of hydrolyzed wheat protein in milk protein-based milk replacers on the performance of intensively fed Holstein calves

The objectives of this study were to compare 2 milk replacers containing only milk proteins with or without supplemental Met, and to compare a milk replacer containing hydrolyzed wheat protein at 4.5% of dry matter (DM) and supplemental Lys and Met against the 2 all-milk-protein formulas, by assessing their effect on the growth performance, efficiency, and plasma urea nitrogen of pre-weaning Holstein calves. Thus, 57 Holstein calves were allotted to the following 3 treatments: (1) a skim milk plus whey protein concentrate-based milk replacer (SMWP) containing about 2.6% Lys and 0.6% Met on a DM basis; (2) SMWP + M based on skim milk and whey proteins, containing about 2.6% Lys, and supplemental Met to reach 0.9% on a DM basis; and (3) a skim milk plus whey protein concentrate plus 4.5% of the DM as hydrolyzed wheat protein based milk replacer (HWP + LM) where the wheat protein replaced 50% of the whey protein concentrate, and also contained supplemental Lys and Met to match the profile of SMWP + M (i.e., Lys 2.6 and Met 0.9% on DM basis). No difference in any of the responses was observed by supplementing the milk protein based formula with Met or when hydrolyzed wheat protein was added to the formula. Results indicate that (1) a milk replacer based on skim milk protein and whey protein with a Lys concentration of ~2.6% does not benefit from Met supplementation, and (2) milk replacer containing 4.5% of the DM as hydrolyzed wheat protein and supplemented with Lys and Met can support the same growth performance as milk protein-based formulas.

Differential expression of 11β-hydroxysteroid dehydrogenase type 1 and 2 in mild and moderate/severe persistent allergic nasal mucosa and regulation of their expression by Th2 cytokines: asthma and rhinitis

BACKGROUND

Glucocorticoids are used to treat allergic rhinitis, but the mechanisms by which they induce disease remission are unclear. 11β-hydroxysteroid dehydrogenase (11β-HSD) is a tissue-specific regulator of glucocorticoid responses, inducing the interconversion of inactive and active glucocorticoids.

OBJECTIVE

We analysed the expression and distribution patterns of 11β-HSD1, 11β-HSD2, and steroidogenic enzymes in normal and allergic nasal mucosa, and cytokine-driven regulation of their expression. The production levels of cortisol in normal, allergic nasal mucosa and in cultured epithelial cells stimulated with cytokines were also determined.

METHODS

The expression levels of 11β-HSD1, 11β-HSD2, steroidogenic enzymes (CYP11B1, CYP11A1), and cortisol in normal, mild, and moderate/severe persistent allergic nasal mucosa were assessed by real-time PCR, Western blot, immunohistochemistry, and ELISA. The expression levels of 11β-HSD1, 11β-HSD2, CYP11B1, CYP11A1, and cortisol were also determined in cultured nasal epithelial cell treated with IL-4, IL-5, IL-13, IL-17A, and IFN-γ. Conversion ratio of cortisone to cortisol was evaluated using siRNA technique, 11β-HSD1 inhibitor, and the measurement of 11β-HSD1 activity.

RESULTS

The expression levels of 11β-HSD1, CYP11B1, and cortisol were up-regulated in mild and moderate/severe persistent allergic nasal mucosa. By contrast, 11β-HSD2 expression was decreased in allergic nasal mucosa. In cultured epithelial cells treated with IL-4, IL-5, IL-13, and IL-17A, 11β-HSD1 expression and activity increased in parallel with the expression levels of CYP11B1 and cortisol, but the production of 11β-HSD2 decreased. CYP11A1 expression level was not changed in allergic nasal mucosa or in response to stimulation with cytokines. SiRNA technique or the measurement of 11β-HSD1 activity showed that nasal epithelium activates cortisone to cortisol in a 11β-HSD-dependent manner.

CONCLUSIONS AND CLINICAL RELEVANCE

These results indicate that the localized anti-inflammatory effects of glucocorticoids are regulated by inflammatory cytokines, which can modulate the expression of 11β-HSD1, 11β-HSD2, and CYP11B1, and by the intracellular concentrations of bioactive glucocorticoids.