NLRC5

A new study identifies NLRC5 as an innate immune sensor that plays a crucial role in PANoptotic cell death -- making it a key therapeutic target. The innate immune system is responsible for protecting the human body from threats that could cause disease or infection. The system relies on innate immune sensors to detect and transmit signals about these threats. One of the key innate immune strategies to respond to threats is through cell death. New research from St. Jude Children's Research Hospital discovered that NLRC5 plays a previously unknown role as an innate immune sensor, triggering cell death. The findings, published in Cell, show how NLRC5 drives PANoptosis, a prominent type of inflammatory cell death. This understanding has implications for the development of therapeutics that target NLRC5 for the treatment of infections, inflammatory diseases and aging. Depending on the threat, innate immune sensors can assemble complexes such as inflammasomes or PANoptosomes. The inflammasome can be thought of like an emergency broadcast system that is activated quickly, while the PANoptosome is more like an emergency response unit that generally integrates more signals and components to respond to the threat. How innate immune sensors work -- what triggers them to act -- has been a mystery, which researchers have been chipping away at for decades. Nucleotide-binding oligomerization domain-like receptors (NLRs) are a large family of important molecules involved in inflammatory signaling. They are generally thought to function as innate immune sensors that detect threats. However, the specific roles of several NLRs in sensing are not yet understood. Scientists at St. Jude conducted a large screen, testing a specific NLR, NLRC5, to see what threats activate it. Through their efforts, they discovered that depletion of nicotinamide adenine dinucleotide (NAD), a molecule essential in energy production, triggers NLRC5-mediated cell death through PANoptosis. "One of the biggest questions in the fields of immunology and innate immunity is what the various members of the NLR family are sensing, and what their functions are," said corresponding author Thirumala-Devi Kanneganti, PhD, St. Jude Department of Immunology vice chair. "NLRC5 was an enigmatic molecule, but now we have the answer -- it is acting as an innate immune sensor and cell death regulator, driving inflammatory cell death, PANoptosis, by forming a complex." Identifying the NLRC5 trigger Scientists in the Kanneganti lab conducted a rigorous screen to get to the bottom of what threats trigger NLRC5. This included looking at pathogens such as bacteria and viruses, as well as pathogen associated molecular patterns (PAMPs) and damage associated molecular patterns (DAMPs) that can be released by or mimic an infection or the cause of an injury or illness, as well as other danger signals such as cytokines (immune signaling molecules). The researchers also looked at heme, the component of hemoglobin responsible for carrying oxygen. Infections or disease can cause red blood cells to rupture in a process called hemolysis. This releases hemoglobin into the bloodstream. When hemoglobin breaks down into its components, it releases free heme, which is known to cause significant inflammation and organ damage. The researchers tested many different combinations of pathogens, PAMPs and DAMPs to see if NLRC5 was required for a response. "Among all the combinations we tested, we identified that the combination of heme plus PAMPs or cytokines specifically induces NLRC5-dependent inflammatory cell death, PANoptosis," said co-first author Balamurugan Sundaram, PhD, St. Jude Department of Immunology. "Our results showed for the first time that NLRC5 is central to responses to hemolysis, which can occur during infections, inflammatory diseases and cancers." Energy depletion triggers NLRC5 function Upon identifying the heme-containing PAMP, DAMP and cytokine combinations that trigger NLRC5-dependent inflammatory cell death, the researchers further investigated how NLRC5 is regulated. They found that NAD levels drive NLRC5 protein expression. If NAD is depleted, that sounds an alarm that there is a threat the immune system should recognize. The researchers found that depletion of NAD is sensed by NLRC5, triggering PANoptosis. "By supplementing with the NAD precursor, nicotinamide, we reduced NLRC5 protein expression and PANoptosis," said co-first author Nagakannan Pandian, PhD, St. Jude Department of Immunology. "Therapeutically, nicotinamide has been widely studied as a nutrient supplement, and our findings suggest it could be helpful in treating inflammatory diseases." The researchers also discovered that NLRC5 is in an NLR network with NLRP12, which come together with other cell death molecules and form an NLRC5-PANoptosome complex that triggers inflammatory cell death. The finding builds on previous research by the Kanneganti lab showcasing the role of NLRP12 in PANoptosis. A promising target for therapeutic development NLRs are associated with diseases related to infection, inflammation, cancers and aging. This makes them intriguing targets for the development of novel therapeutics. The work of the Kanneganti lab shows that deleting Nlrc5 can provide protection against inflammatory cell death through PANoptosis and prevent disease pathology in hemolytic and inflammatory disease models, making NLRC5 an exciting therapeutic prospect. "The fundamental knowledge that we have gained into how innate immune sensing works can be translated to numerous diseases and conditions," Kanneganti said. "Aging, infectious disease, inflammatory disorders -- things for which there are no targeted therapies, this could be an option." Authors and funding The study's other authors are Emily Alonzo, Department of Research and Development at Cell Signaling Technology; and Hee Jin Kim, Hadia Abdelaal, Omkar Indari, Roman Sarkar, Rebecca Tweedell, Jonathan Klein, Shondra Pruett-Miller and Peter Vogel, all of St. Jude, and Raghvendra Mall, formerly of St. Jude now of the Technology Innovation Institute, Abu Dhabi. The study was supported by grants from the National Institutes of Health (AI101935, AI124346, AI160179, AR056296 and CA253095) and ALSAC, the fundraising and awareness organization of St. Jude.

Promising Preclinical Data Highlights a Simple One-Step Gene Editing Strategy to Prevent the Rejection of AlloCAR T™ Cells by Host T Cells and NK Cells Cloaking Approach Demonstrates Superiority to B2M Knock Out in a Syngeneic In Vivo Model Proprietary Approach Is One of Several Next Generation Technologies Being Pioneered at Allogene to Control Rejection SOUTH SAN FRANCISCO, Calif., Nov. 10, 2022 (GLOBE NEWSWIRE) -- Allogene Therapeutics, Inc. (Nasdaq: ALLO), a clinical-stage biotechnology company pioneering the development of allogeneic CAR T (AlloCAR T™) products for cancer, today presented pre-clinical data on a novel approach to immune “cloaking” designed to protect AlloCAR T™ cells from rapid host rejection. The technology is designed to prevent AlloCAR T™ cells from being recognized by host T cells without triggering substantial natural killer (NK) cell rejection and while preserving CAR T cell function. The findings were presented today during a poster session at the 37th Annual Meeting of the Society for Immunotherapy of Cancer (SITC). The development of “off-the-shelf” (allogeneic) CAR T products that utilize cells from healthy donors have the potential to make CAR T therapies scalable and accessible to more patients. The effectiveness of allogeneic CAR T cells requires controlling immune rejection of allogeneic CAR T cells by the patient’s immune cells, namely T and NK cells. Allogene is currently developing ALLO-647, a lymphodepletion agent which targets host immune cells but not AlloCAR T™ cells, to enhance the window of CAR T engraftment, but is also investigating several novel strategies that may enhance the performance of allogeneic CAR T products by controlling immune rejection. This preclinical study evaluated an alternative approach to immune evasion by selectively targeting NLRC5 and RFX5, transcriptional regulators that control expression of HLA molecules. NLRC5 knockout avoids CD8 T cell mediated rejection and RFX5 knockout avoids rejection by both CD8 and CD4 T cells, allowing the possibility to avoid a broader spectrum of T cell-mediated rejection with just one edit, in contrast to alternative approaches that require two edits. “We believe that novel approaches to cloaking may further increase the efficacy of off-the-shelf CAR T products through avoidance of immune rejection,” said Barbra Sasu, Ph.D. Chief Scientific Officer at Allogene. “As we look to deliver on the promise of AlloCAR T cell products, we are investigating several novel approaches to supplement or potentially even replace our current platform for immune rejection avoidance. The data presented today is promising, showing that knockout of NLRC5 and RFX5 reduced T cell rejection whilst minimizing NK cell rejection and without impacting CAR T cell performance.” In the study, the survival of “cloaked” cells was assessed in mixed lymphocyte reaction assays with T cells, NK cells, or a combined assay with T and NK cells. The knockout of NLRC5 or RFX5 in allogeneic CAR T cells enhanced survival in the presence of host T cells and elicited only minor NK cell reactivity, thereby effectively mitigating rejection. Importantly, the inactivation of NLRC5 or RFX5 did not impact CAR T cell phenotype or cytotoxic activity. The NLRC5 or RFX5 edited CAR T cells also demonstrated superior persistence and anti-tumor efficacy compared to un-edited CAR T cells or B2M edited CAR T cells in a stringent syngeneic model in vivo. These modifications would be designed to be part of an overall editing and gene expression platform to avoid CAR T rejection. About Allogene Therapeutics Allogene Therapeutics, with headquarters in South San Francisco, is a clinical-stage biotechnology company pioneering the development of allogeneic chimeric antigen receptor T cell (AlloCAR T™) products for cancer. Led by a management team with significant experience in cell therapy, Allogene is developing a pipeline of “off-the-shelf” CAR T cell candidates with the goal of delivering readily available cell therapy on-demand, more reliably, and at greater scale to more patients. For more information, please visit and follow @AllogeneTx on Twitter and LinkedIn. Cautionary Note on Forward-Looking Statements This press release contains forward-looking statements for purposes of the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. The press release may, in some cases, use terms such as "predicts," "believes," "potential," "proposed," "continue," "estimates," "anticipates," "expects," "plans," "intends," "may," "could," "might," "will," "should" or other words that convey uncertainty of future events or outcomes to identify these forward-looking statements. Forward-looking statements include statements regarding intentions, beliefs, projections, outlook, analyses or current expectations concerning, among other things: the ability to research and develop technologies to protect AlloCAR T™ cells from rapid host rejection; the ability of NLRC5 or RFX5 edited CAR T cells to demonstrate persistence and antitumor efficacy; and the potential benefits of ALLO-647 and AlloCAR T products. Various factors may cause differences between Allogene’s expectations and actual results as discussed in greater detail in Allogene’s filings with the SEC, including without limitation in its Form 10-Q for the quarter ended September 30, 2022. Any forward-looking statements that are made in this press release speak only as of the date of this press release. Allogene assumes no obligation to update the forward-looking statements whether as a result of new information, future events or otherwise, after the date of this press release. AlloCAR T™ is a trademark of Allogene Therapeutics, Inc. Allogene Media/Investor Contact: Christine Cassiano Chief Communications Officer (714) 552-0326 Christine.Cassiano@allogene.com