{"id":4689,"date":"2025-09-15T02:05:51","date_gmt":"2025-09-15T07:05:51","guid":{"rendered":"https:\/\/www.bocsci.com\/blog\/?p=4689"},"modified":"2025-09-15T02:06:58","modified_gmt":"2025-09-15T07:06:58","slug":"pseudouridine-modified-mrna-how-it-evades-immune-detection-via-tlr7-8-suppression","status":"publish","type":"post","link":"https:\/\/www.bocsci.com\/blog\/pseudouridine-modified-mrna-how-it-evades-immune-detection-via-tlr7-8-suppression\/","title":{"rendered":"Pseudouridine-Modified mRNA: How It Evades Immune Detection via TLR7\/8 Suppression"},"content":{"rendered":"\n<h2><strong>Introduction<\/strong><strong><\/strong><\/h2>\n\n\n\n<p><a href=\"https:\/\/www.bocsci.com\/tag\/toll-like-receptor-tlr-25.html\">Toll-like receptors (TLRs)<\/a>&nbsp;play a crucial role in innate immunity by detecting foreign RNA and triggering immune responses. Among these, TLR7 and TLR8 recognize RNA degradation products in endolysosomal compartments, activating antiviral defenses. However, endogenous RNA modifications, such as pseudouridine (\u03a8), enable RNA to evade immune detection\u2014a feature critical for the success of mRNA-based therapeutics.<\/p>\n\n\n\n<p>Despite the widespread use of \u03a8-modified mRNA in vaccines and therapies, the molecular mechanisms underlying its immune evasion properties have remained unclear. In a groundbreaking study published in Cell, B\u00e9routi <em>et al.<\/em>&nbsp;systematically dissect how \u03a8-modified RNA avoids TLR7\/8 activation by impairing endolysosomal processing and reducing receptor engagement. Their findings also reveal an unexpected TLR8-stimulatory effect of N1-methylpseudouridine (m1\u03a8), a common therapeutic modification, raising important considerations for future mRNA drug design.<\/p>\n\n\n\n<h2><strong>Key Findings<\/strong><strong><\/strong><\/h2>\n\n\n\n<h3>1.&nbsp;<strong>Pseudouridine-Modified RNA Resists Endolysosomal Degradation<\/strong><strong><\/strong><\/h3>\n\n\n\n<p>TLR7\/8 activation depends on the cleavage of RNA by endolysosomal nucleases, particularly RNase T2, which preferentially cuts at purine-uridine (RU) dinucleotide sites. The study demonstrates that \u03a8 modification disrupts RNase T2 activity, preventing the generation of immunostimulatory RNA fragments.<\/p>\n\n\n\n<ul>\n<li>Mass spectrometry analysis confirmed that \u03a8-modified RNA is poorly processed by RNase T2.<\/li>\n\n\n\n<li>Exonucleases PLD3\/PLD4, which further degrade RNA fragments for TLR activation, also exhibit reduced activity against \u03a8-RNA.<\/li>\n\n\n\n<li>Structural studies revealed that \u03a8 stabilizes RNA in an A-helical conformation, hindering nuclease binding and cleavage.<\/li>\n<\/ul>\n\n\n\n<p>As a result, \u03a8-modified in vitro transcribed (IVT) RNA failed to induce TLR7\/8-dependent cytokine secretion in human primary monocytes, plasmacytoid dendritic cells (pDCs), and BLaER1 monocyte models.<strong><\/strong><\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><a href=\"https:\/\/www.bocsci.com\/blog\/wp-content\/uploads\/2025\/09\/RNase-T2-or-RNase-1-cleavage-patterns-of-\u03a8-modified-vs.-unmodified-RNA.jpg\"><img decoding=\"async\" loading=\"lazy\" width=\"739\" height=\"1024\" src=\"https:\/\/www.bocsci.com\/blog\/wp-content\/uploads\/2025\/09\/RNase-T2-or-RNase-1-cleavage-patterns-of-\u03a8-modified-vs.-unmodified-RNA-739x1024.jpg\" alt=\"RNase T2 or RNase 1 cleavage patterns of \u03a8-modified vs. unmodified RNA\" class=\"wp-image-4692\" srcset=\"https:\/\/www.bocsci.com\/blog\/wp-content\/uploads\/2025\/09\/RNase-T2-or-RNase-1-cleavage-patterns-of-\u03a8-modified-vs.-unmodified-RNA-739x1024.jpg 739w, https:\/\/www.bocsci.com\/blog\/wp-content\/uploads\/2025\/09\/RNase-T2-or-RNase-1-cleavage-patterns-of-\u03a8-modified-vs.-unmodified-RNA-216x300.jpg 216w, https:\/\/www.bocsci.com\/blog\/wp-content\/uploads\/2025\/09\/RNase-T2-or-RNase-1-cleavage-patterns-of-\u03a8-modified-vs.-unmodified-RNA-768x1064.jpg 768w, https:\/\/www.bocsci.com\/blog\/wp-content\/uploads\/2025\/09\/RNase-T2-or-RNase-1-cleavage-patterns-of-\u03a8-modified-vs.-unmodified-RNA-1108x1536.jpg 1108w, https:\/\/www.bocsci.com\/blog\/wp-content\/uploads\/2025\/09\/RNase-T2-or-RNase-1-cleavage-patterns-of-\u03a8-modified-vs.-unmodified-RNA.jpg 1267w\" sizes=\"(max-width: 739px) 100vw, 739px\" \/><\/a><\/figure>\n\n\n\n<p>Figure 1&nbsp;RNase T2 or RNase 1 cleavage patterns of \u03a8-modified vs. unmodified RNA<sup>1,2<\/sup><\/p>\n\n\n\n<h3><strong>2. Weak TLR8 Activation by Pseudouridine<\/strong><strong><\/strong><\/h3>\n\n\n\n<p>Beyond impaired RNA processing, \u03a8 itself is a poor activator of TLR8.<\/p>\n\n\n\n<ul>\n<li>Biochemical assays showed that while uridine (U) and m1\u03a8 induce TLR8 dimerization (a hallmark of receptor activation), \u03a8 has minimal activity.<\/li>\n\n\n\n<li>When co-delivered with RNA fragments occupying TLR8\u2019s second binding pocket, \u03a8 exhibited weak synergistic activation, suggesting it retains some binding capacity.<\/li>\n<\/ul>\n\n\n\n<p>Notably, m1\u03a8\u2014a common mRNA therapeutic modification\u2014retained TLR8-stimulatory activity similar to U, despite resisting nuclease degradation. This finding has implications for mRNA vaccine design, as m1\u03a8 may enhance translation efficiency but also carry a risk of off-target immune activation.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><a href=\"https:\/\/www.bocsci.com\/blog\/wp-content\/uploads\/2025\/09\/2-\u03a8-is-a-weak-agonist-of-TLR8-compared-to-U-and-m1\u03a8.jpg\"><img decoding=\"async\" loading=\"lazy\" width=\"753\" height=\"806\" src=\"https:\/\/www.bocsci.com\/blog\/wp-content\/uploads\/2025\/09\/2-\u03a8-is-a-weak-agonist-of-TLR8-compared-to-U-and-m1\u03a8.jpg\" alt=\"2 \u03a8 is a weak agonist of TLR8 compared to U and m1\u03a8\" class=\"wp-image-4693\" srcset=\"https:\/\/www.bocsci.com\/blog\/wp-content\/uploads\/2025\/09\/2-\u03a8-is-a-weak-agonist-of-TLR8-compared-to-U-and-m1\u03a8.jpg 753w, https:\/\/www.bocsci.com\/blog\/wp-content\/uploads\/2025\/09\/2-\u03a8-is-a-weak-agonist-of-TLR8-compared-to-U-and-m1\u03a8-280x300.jpg 280w\" sizes=\"(max-width: 753px) 100vw, 753px\" \/><\/a><\/figure>\n\n\n\n<p>Figure 2 \u03a8 is a weak agonist of TLR8 compared to U and m1\u03a8<sup>3,2<\/sup><\/p>\n\n\n\n<h3><strong>3. Dual Mechanisms of TLR7 Evasion<\/strong><strong><\/strong><\/h3>\n\n\n\n<p>TLR7 activation requires two ligands:<\/p>\n\n\n\n<ul>\n<li>2\u2032,3\u2032-cyclic guanosine monophosphate (2\u2032,3\u2032-cGMP) (binding pocket 1)<\/li>\n\n\n\n<li>Short oligonucleotides (ORN) (binding pocket 2)<\/li>\n<\/ul>\n\n\n\n<p>\u03a8-modified RNA disrupts this process in two ways:<\/p>\n\n\n\n<ul>\n<li>Impaired generation of 2\u2032,3\u2032-cGMP due to resistance to RNase T2 and PLD nucleases.<\/li>\n\n\n\n<li>Failure of \u03a8-containing ORNs to activate TLR7, even when 2\u2032,3\u2032-cGMP is provided exogenously.<\/li>\n<\/ul>\n\n\n\n<p>Mouse studies confirmed that RNase T2 knockout significantly reduced IFN\u03b1 responses to unmodified mRNA, highlighting its essential role in TLR7-dependent RNA sensing.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><a href=\"https:\/\/www.bocsci.com\/blog\/wp-content\/uploads\/2025\/09\/3-\u03a8-inhibits-2-3-cGMP-release-required-for-TLR7-activation.jpg\"><img decoding=\"async\" loading=\"lazy\" width=\"666\" height=\"941\" src=\"https:\/\/www.bocsci.com\/blog\/wp-content\/uploads\/2025\/09\/3-\u03a8-inhibits-2-3-cGMP-release-required-for-TLR7-activation.jpg\" alt=\"3 \u03a8 inhibits 2\u2032,3\u2032-cGMP release required for TLR7 activation\" class=\"wp-image-4694\" srcset=\"https:\/\/www.bocsci.com\/blog\/wp-content\/uploads\/2025\/09\/3-\u03a8-inhibits-2-3-cGMP-release-required-for-TLR7-activation.jpg 666w, https:\/\/www.bocsci.com\/blog\/wp-content\/uploads\/2025\/09\/3-\u03a8-inhibits-2-3-cGMP-release-required-for-TLR7-activation-212x300.jpg 212w\" sizes=\"(max-width: 666px) 100vw, 666px\" \/><\/a><\/figure>\n\n\n\n<p>Figure 3 \u03a8 inhibits 2\u2032,3\u2032-cGMP release required for TLR7 activation<sup>4,2<\/sup><\/p>\n\n\n\n<h2><strong>Implications for mRNA Therapeutics and Immune Tolerance<\/strong><strong><\/strong><\/h2>\n\n\n\n<p>This study presents an integrated model for how \u03a8-modified RNA evades TLR7\/8 detection:<\/p>\n\n\n\n<ul>\n<li>Obstructs nuclease processing (RNase T2\/PLD3\/PLD4)<\/li>\n\n\n\n<li>Reduces TLR8 binding affinity<\/li>\n\n\n\n<li>Prevents TLR7 ligand generation and engagement<\/li>\n<\/ul>\n\n\n\n<p>Key Takeaways:<\/p>\n\n\n\n<ul>\n<li>\u03a8-modified mRNA avoids immune detection, explaining its success in vaccines.<\/li>\n\n\n\n<li>m1\u03a8 retains TLR8-stimulatory activity, potentially leading to unintended immune responses.<\/li>\n\n\n\n<li>Endogenous \u03a8 modifications may help distinguish self vs. non-self RNA, preventing autoimmunity.<\/li>\n<\/ul>\n\n\n\n<p>Future research should explore whether other RNA modifications (e.g., 2\u2032-O-methylation) cooperate with \u03a8 to maintain immune tolerance.<\/p>\n\n\n\n<h2><strong>Applications &amp; Product Recommendation<\/strong><strong><\/strong><\/h2>\n\n\n\n<p>If you are developing mRNA-based therapeutics, vaccines, or gene therapies, selecting the right nucleoside modifications is critical for balancing translation efficiency and immune safety.<\/p>\n\n\n\n<p>Our Recommended Solution:<\/p>\n\n\n\n<p>BOC Sciences\u2019s&nbsp;High-Purity<a href=\"https:\/\/www.bocsci.com\/pseudouridine-and-its-derivatives.html\">&nbsp;Pseudouridine Nucleoside<\/a><\/p>\n\n\n\n<ul>\n<li>\u226599% purity, GMP-grade or research-grade available<\/li>\n\n\n\n<li>Optimized for <em>in vitro<\/em>&nbsp;transcription (IVT) and large-scale mRNA synthesis<\/li>\n\n\n\n<li>Enhances RNA stability and reduces innate immune activation<\/li>\n\n\n\n<li>Compatible with lipid nanoparticle (LNP) delivery systems<\/li>\n<\/ul>\n\n\n\n<p><strong>Why choose our pseudouridine?<\/strong><\/p>\n\n\n\n<ul>\n<li>Proven to reduce TLR7\/8 recognition<\/li>\n\n\n\n<li>Supports higher mRNA translation without triggering strong cytokine responses<\/li>\n\n\n\n<li>Trusted by vaccine manufacturers and biotech R&amp;D teams<\/li>\n<\/ul>\n\n\n\n<p><a href=\"https:\/\/www.bocsci.com\/contactus.html\">Contact us today<\/a>&nbsp;to request a free sample or bulk pricing.<\/p>\n\n\n\n<h2><strong>Commom PseudoUridine<\/strong><strong>&nbsp;at BOC Sciences<\/strong><strong><\/strong><\/h2>\n\n\n\n<figure class=\"wp-block-table\"><table><tbody><tr><td>CAS<\/td><td>Product Name<\/td><td>Category<\/td><\/tr><tr><td>1445-07-4<\/td><td><a href=\"https:\/\/www.bocsci.com\/product\/pseudouridine-cas-1445-07-4-84156.html\">\u03b2-pseudoUridine<\/a><\/td><td>Unmodified pseudoUridine<\/td><\/tr><tr><td>39967-60-7<\/td><td><a href=\"https:\/\/www.bocsci.com\/2-deoxypseudouridine-cas-39967-60-7-item-180050.html\">2\u2032-DeoxypseudoUridine<\/a><\/td><td>Unmodified pseudoUridine<\/td><\/tr><tr><td>10017-66-0<\/td><td><a href=\"https:\/\/www.bocsci.com\/pseudouridine-b-cas-10017-66-0-item-158431.html\">\u03b1-pseudoUridine<\/a><\/td><td>Unmodified pseudoUridine<\/td><\/tr><tr><td>64272-68-0<\/td><td><a href=\"https:\/\/www.bocsci.com\/1-3-dimethylpseudouridine-cas-64272-68-0-item-207505.html\">1,3-DimethylpseudoUridine<\/a><\/td><td>Base modified pseudoUridine<\/td><\/tr><tr><td>81691-06-7<\/td><td><a href=\"https:\/\/www.bocsci.com\/product\/3-methylpseudouridine-cas-81691-06-7-340278.html\">N3-MethylpseudoUridine<\/a><\/td><td>Base modified pseudoUridine<\/td><\/tr><tr><td>13860-38-3<\/td><td><a href=\"https:\/\/www.bocsci.com\/product\/1-methylpseudouridine-cas-13860-38-3-207673.html\">N1-MethylpseudoUridine<\/a><\/td><td>Base modified pseudoUridine<\/td><\/tr><tr><td>1157-60-4<\/td><td><a href=\"https:\/\/www.bocsci.com\/product\/pseudouridine-5-monophosphate-cas-1157-60-4-339789.html\">PseudoUridine 5\u2032-monophosphate<\/a><\/td><td>Monophosphate pseudoUridine<\/td><\/tr><tr><td>&nbsp;<\/td><td><a href=\"https:\/\/www.bocsci.com\/product\/pseudouridine-5-triphosphate-cas-1175-34-4-263749.html\">PseudoUridine-5\u2032-Triphosphate<\/a><\/td><td>Triphosphate pseudoUridine<\/td><\/tr><tr><td>&nbsp;<\/td><td><a href=\"https:\/\/www.bocsci.com\/product\/n1-methylpseudouridine-5-triphosphate-sodium-358101.html\">N1-MethylpseudoUridine-5&#8242;-Triphosphate Sodium<\/a><\/td><td>Triphosphate pseudoUridine<\/td><\/tr><tr><td>&nbsp;<\/td><td><a href=\"https:\/\/www.bocsci.com\/product\/pseudouridine-5-triphosphate-sodium-358098.html\">PseudoUridine 5&#8242;-Triphosphate Sodium<\/a><\/td><td>Triphosphate pseudoUridine<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<h2><strong>Conclusion<\/strong><strong><\/strong><\/h2>\n\n\n\n<p>The work by B\u00e9routi <em>et al.<\/em>&nbsp;provides a mechanistic foundation for understanding how \u03a8-modified RNA evades TLR7\/8 detection, offering critical insights for mRNA vaccine and therapeutic design. Their discovery that m1\u03a8 retains TLR8 activity suggests a trade-off between translation efficiency and immunogenicity, guiding future optimization of synthetic mRNA constructs.<\/p>\n\n\n\n<p>For more details, read the full paper:<\/p>\n\n\n\n<p>B\u00e9routi M, Wagner M, Greulich W, <em>et al.<\/em>&nbsp;Pseudouridine RNA avoids immune detection through impaired endolysosomal processing and TLR engagement. Cell. 2025. doi: 10.1016\/j.cell.2025.05.032<\/p>\n\n\n\n<p><strong>References<\/strong><strong><\/strong><\/p>\n\n\n\n<ol type=\"1\">\n<li>Image retrieved from Figure 1 &#8220;Characterization of ssRNA digested with RNase T2 or RNase 1,&#8221; B\u00e9routi, Marleen, <em>et al<\/em>., 2025, used under [CC BY 4.0](https:\/\/creativecommons.org\/licenses\/by\/4.0\/). The original image was modified by extracting and using only part a, and the title was changed to &#8220;RNase T2 or RNase 1 cleavage patterns of \u03a8-modified vs. unmodified RNA\u201d<\/li>\n\n\n\n<li>B\u00e9routi, Marleen, <em>et al. <\/em>&#8220;Pseudouridine RNA avoids immune detection through impaired endolysosomal processing and TLR engagement.&#8221; Cell (2025).<\/li>\n\n\n\n<li>Image retrieved from Figure 5&nbsp;&#8220;\u03a8 is a poor ligand for TLR8,&#8221; B\u00e9routi, Marleen,<em>&nbsp;et al.<\/em>, 2025, used under [CC BY 4.0](https:\/\/creativecommons.org\/licenses\/by\/4.0\/). The original image was modified by extracting and using only part a, and the title was changed to &#8220;\u03a8 is a weak agonist of TLR8 compared to U and m1\u03a8\u201d<\/li>\n\n\n\n<li>Image retrieved from Figure 6&nbsp;&#8220;\u03a8 inhibits the release of 2\u2032,3\u2032-cGMP for TLR7 activation,&#8221; B\u00e9routi, Marleen, <em>et al.<\/em>, 2025, used under [CC BY 4.0](https:\/\/creativecommons.org\/licenses\/by\/4.0\/). The original image was modified by extracting and using only part a, and the title was changed to &#8220;\u03a8 inhibits 2\u2032,3\u2032-cGMP release required for TLR7 activation\u201d<\/li>\n<\/ol>\n","protected":false},"excerpt":{"rendered":"<p>Introduction Toll-like receptors (TLRs)&nbsp;play a crucial role in innate immunity by detecting foreign RNA and triggering immune responses. Among these, TLR7 and TLR8 recognize RNA degradation products in endolysosomal compartments, [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[1],"tags":[],"_links":{"self":[{"href":"https:\/\/www.bocsci.com\/blog\/wp-json\/wp\/v2\/posts\/4689"}],"collection":[{"href":"https:\/\/www.bocsci.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.bocsci.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.bocsci.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.bocsci.com\/blog\/wp-json\/wp\/v2\/comments?post=4689"}],"version-history":[{"count":2,"href":"https:\/\/www.bocsci.com\/blog\/wp-json\/wp\/v2\/posts\/4689\/revisions"}],"predecessor-version":[{"id":4697,"href":"https:\/\/www.bocsci.com\/blog\/wp-json\/wp\/v2\/posts\/4689\/revisions\/4697"}],"wp:attachment":[{"href":"https:\/\/www.bocsci.com\/blog\/wp-json\/wp\/v2\/media?parent=4689"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.bocsci.com\/blog\/wp-json\/wp\/v2\/categories?post=4689"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.bocsci.com\/blog\/wp-json\/wp\/v2\/tags?post=4689"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}