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Once considered a tissue culture-specific phenomenon, cellular senescence has now been linked to various biological processes with both beneficial and detrimental roles in humans, rodents and other species. Much of our understanding of senescent cell biology still originates from tissue culture studies, where each cell in the culture is driven to an irreversible cell cycle arrest. By contrast, in tissues, these cells are relatively rare and difficult to characterize, and it is now established that fully differentiated, postmitotic cells can also acquire a senescence phenotype. The SenNet Biomarkers Working Group was formed to provide recommendations for the use of cellular senescence markers to identify and characterize senescent cells in tissues. Here, we provide recommendations for detecting senescent cells in different tissues based on a comprehensive analysis of existing literature reporting senescence markers in 14 tissues in mice and humans. We discuss some of the recent advances in detecting and characterizing cellular senescence, including molecular senescence signatures and morphological features, and the use of circulating markers. We aim for this work to be a valuable resource for both seasoned investigators in senescence-related studies and newcomers to the field., Competing Interests: Competing interests: The authors declare the following competing interests: J.C. is a founder and shareholder of Unity Biotechnology, which develops senolytic drugs. M.J.S., C.M.C. and Mayo Clinic have intellectual property related to this research. Research in the M.J.S. and D.J.B. laboratory is reviewed by the Mayo Clinic Conflict of Interest Review Board and conducted in compliance with Mayo Clinic Conflict of Interest policies. D.J.B. has a potential financial interest related to this research; he is a co-inventor on patents held by Mayo Clinic and patent applications licensed to or filed by Unity Biotechnology and a Unity Biotechnology shareholder. N. Slavov is a founding director and CEO of Parallel Squared Technology Institute, which is a non-profit research institute., (© 2024. Springer Nature Limited.)

Background: Cancer immunotherapy has revolutionized melanoma treatment, but the high number of non-responders still emphasizes the need for improvement of therapy. One potential avenue for enhancing anti-tumor treatment is through the modulation of coagulation and platelet activity. Both have been found to play an important role in the tumor microenvironment, tumor growth and metastasis. Preclinical studies indicate a beneficial effect, clinical data has been inconsistent., Methods: We examined a cohort of advanced, non-resectable melanoma patients (n = 2419) derived from the German prospective multicenter skin cancer registry ADOReg, who were treated with immune checkpoint inhibitors (ICI). The patients were classified based on whether it was documented that they received platelet aggregation inhibition (PAI) (n = 137) (acetylsalicylic acid (ASA) or clopidogrel), anticoagulation (AC) (n = 185) (direct oral anticoagulation (DOAC), phenprocoumon, heparins) at the start of ICI or no antithrombotic medication (n = 2097) at any point during ICI treatment. The study endpoints were best overall response (BOR), progression-free survival (PFS) and overall survival (OS)., Results: A significantly improved PFS was observed in patients documented to receive ASA (15.1 vs 6.4 months, HR 0.67, 95 % CI: 0.5 to 0.88, p = 0.0047) as well as in patients to receive AC (15.1 vs. 6.4 months, HR 0.7, 95 % CI: 0.53 to 0.91, p = 0.01) compared to patients for whom no antithrombotic medication was documented. Multivariate analysis of OS showed significant risk reduction in patients who received DOAC (HR 0.68, 95 % CI: 0.49 to 0.92, p = 0.0170) or phenprocoumon (HR: 0.44, 95 % CI: 0.19 to 0.85, p = 0.0301)., Conclusion: Our study indicates a positive prognostic effect of anticoagulant and antiplatelet concomitant medication in melanoma patients receiving ICI. Further studies are needed to confrim the cancer-related benefit of adding anticoagulation or platelet inhibition to ICI treatment., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: JK has received honoraria from Bristol-Myers Squibb and Sanofi Genzyme and has received travel support from SUN Pharma and Pierre Fabre, outside the submitted work. GG has received honoraria from Bristol-Myers Squibb and has research funding from Sanofi Genzyme, outside the submitted work. IsH has received honoraria from Bristol-Myers Squibb and Sysmex, outside the submitted work. SU declares research support from Bristol Myers Squibb and Merck Serono; speakers and advisory board honoraria from Bristol Myers Squibb, Merck Sharp & Dohme, Merck Serono, and Novartis; and meeting and travel support from Almirall, Bristol-Myers Squibb, IGEA Clinical Biophysics, Merck Sharp & Dohme, Novartis, Pierre Fabre, and Sun Pharma; outside the submitted work. UL declares research support from Merck Sharp & Dohme; speakers and advisory board honoraria from Sanofi, Regeneron, Sun Pharma, Merck Sharp & Dohme, Allmiral and Novartis; and meeting and travel support from Pierre Fabre, and Sun Pharma; outside the submitted work. CB declares honoraria as speaker and/or advisory board member from Almirall Hermal, Bristol-Myers Squibb, Delcath, Immunocore, InflaRx, Leo Pharma, MSD, Novartis, Pierre Fabre, Regeneron, and Sanofi, outside the submitted work. RG received honoraria for lectures/ advisory boards from Bristol Myers Squibb, Merck Sharp Dohme, Novartis, Merck-Serono, Amgen, Almirall Hermal, Pierre-Fabre, Sun Pharma, Immunocore, 4SC, Delcath, Sanofi/ Regeneron; Meeting support SUN Pharma, Boehringer Ingelheim, PierreFabre; Research support (to institution) Novartis, Sanofi/ Regeneron, Merck Serono, Amgen, SUN Pharma, Kyowa Kirin, Almirall Hermal. DS Honoraria: Roche/Genentech, Novartis, Bristol Myers Squibb, Merck Sharp & Dohme, Immunocore, Merck Serono, Array BioPharma, Pfizer, Pierre Fabre, Philogen, Regeneron, 4SC, Sanofi/Regeneron, NeraCare GmbH, Sun Pharma, InflarxGmbH, Ultimovacs, Sandoz. Consulting or Advisory Role: Roche/Genentech, Novartis, Bristol Myers Squibb, Merck Sharp & Dohme, Merck Serono, 4SC, Pierre Fabre, Sanofi/Regeneron, Nektar. Speakers' Bureau: Bristol Myers Squibb, Merck Sharp & Dohme, Novartis, Pierre Fabre, Sanofi/Regeneron, Merck KGaA. Research Funding: Bristol Myers Squibb (Inst), Novartis (Inst), Roche (Inst), MSD Oncology (Inst), Array BioPharma/Pfizer (Inst). Travel, Accommodations, Expenses: Roche/Genentech, Bristol Myers Squibb, Merck Serono, Novartis, Merck Sharp & Dohme, Pierre Fabre, Sanofi/Regeneron. LZ served as consultant and has received honoraria from BMS, MSD, Novartis, Pierre Fabre, Sanofi, and Sunpharma and travel support from MSD, BMS, Pierre Fabre, Sanofi, Sunpharma and Novartis, outside the submitted work. EL served as consultant and/or has received honoraria from Bristol-Myers Squibb, Merck Sharp & Dohme, Novartis, Pierre-Fabre, Sanofi, Sunpharma, Takeda and travel support from Bristol-Myers Squibb, Pierre- Fabre, Sunpharma and Novartis, outside the submitted work. IvW received honorairia as speaker from Novartis, BMS, MSD, Sanofi, Stemline, Kyowa Kirin and as consultant or advisory from BMS, MSD, Sanofi; travel, accommodations and expenses from Novartis, BMS, MSD, Sanofi, Stemline and Kyowa Kirin. FriM has received travel support or/and speaker’s fees or/and advisor’s honoraria by Novartis, BMS, MSD, Pierre Fabre, Sanofi and Immunocore. SH declares speakers and advisory board honoraria and/or travel support from BMS, MSD, Immunocore, Novartis, Pierre-Fabre, Sanofi, Sun Pharma outside the submitted work. KD received financial support (speaker’s honoraria, advisory boards, travel expense reimbursements or grants) from Abbvie, Bristol-Myers-Squib, Novartis, and Pierre-Fabre. JU is on the advisory board or has received honoraria and travel support from Amgen, Bristol Myers Squibb, GSK, Immunocore, LeoPharma, Merck Sharp and Dohme, Novartis, Pierre Fabre, Roche, Sanofi outside the submitted work. SAW received honoria from Bristol Myers Squibb, Novartis and Sun Pharma, outside the submitted work. CP served as consultant and/or has received honoraria from Bristol-Myers Squibb, Merck Sharp & Dohme, Novartis, Sanofi, Sunpharma, Pierre Fabre, AbbVie, Kyona Kirin and Amgen and received travel support from Amgen, Merck Sharp & Dohme, Bristol-Myers Squibb, Pierre Fabre, Sunpharma and Novartis, outside the submitted work. PT served as consultant and/or received honoraria form Almirall, Bristol Myers Squibb, Biofrontera, Kyowa Kirin, L′Oréal, Merck Sharp & Dohme, Novartis, Pierre-Fabre, Sanofi, 4SC, and travel support from Bristol Myers Squibb outside the submitted work. JeU is on the advisory board or has received honoraria and travel support from Bristol Myers Squibb, Merck Sharp and Dohme, Novartis, Pierre Fabre, Regeneron, Roche, Sanofi and SUN Pharma outside the submitted work. FraM served as consultant and/or has received honoraria from Novartis, Bristol-Myers Squibb, Merck Sharp & Dohme, Pierre Fabre, Sanofi Genzyme, Sun Pharma and travel support from Novartis, Sun Pharma, Pierre Fabre and Merck Sharp & Dohme, outside the submitted work. JW has received honoraria and travel support from Abbvie, Almirall, BMS, Boehringer Ingelheim, Janssen, Infectopharm Leo, Lilly, Mibe, MSD, Novartis, Pfizer and Sanofi. BS received honoraria from SUN Pharma, Allmiral, Novartis; Advisory Board for Pierre Fabre Pharma, Sanofi, Immunocore; travel support from Novartis, Pierre Fabre Pharma; Research Funding from Novartis; all outside the submitted work. FZ declares speakers and advisory board honoraria and/or travel support from BMS, MSD, Roche, Novartis, Pierre-Fabre, Sanofi, Sun Pharma outside the submitted work. AK received honoraria as speaker from InfectoPharm, Paul-Ehrlich-Gesellschaft für Chemotherapie e.V., Almirall Hermal, MSD Sharp & Dohme, Boehringer Ingelheim, Janssen-Cilag. LH declares speaker and advisory board honoraria from BMS, Immunocore, Novartis and Therakos. CL received honoraria for advisory board from BMS, MSD, Merck, Roche, Immunocore, Novartis, Pierre Fabre, Sanofi, Sun Pharma, Almirall Hermal, Kyowa Kirin, Biontech, Boehriner Ingelheim; speakers fee from BMS, MSD, Merck, Roche, Immunocore, Novartis, Pierre Fabre, Sanofi, Sun Pharma, Almirall Hermal, Kyowa Kirin, Biontech, Lilly and travel reimbursement from BMS, MSD, Merck, Roche, Immunocore, Novartis, Pierre Fabre, Sanofi, Sun Pharma, Almirall Hermal, Kyowa Kirin, Biontech, Pfizer. GS has received honoraria from Bristol-Myers Squibb and Kyowa Hakko Kirin Co. Ltd. outside the submitted work. SG declares honoraria for advisory boards, oral presentations and/ or travel expenses from Roche, Novartis, MSD, BMS, Sun Pharma, Klinge Pharma, Kyowa Kirin, Pierre Fabre, Guidepoint Global and UCB and research funds from Novartis and Pierre Fabre outside the submitted work. ND received honoraria from BMS and MSD outside the submitted work. RH and IK are employee of Helios Klinikum Erfurt GmbH. CS reports support from Kyowa Kirin, BMS, Novartis, Roche, SunPharma in context of dermatooncology as well as from Boehringer Ingelheim, Biotest AG and Janssen Cilag in other medical fields. AE is on advisory board or has received honoraria from Agenus, BioInvent, BioNTech, Boeringer Ingelheim GmbH, Brenus, CatalYm, Eurobio. IO Biotech, IQVIA, Merck&Co, MSD, Pfizer, Pierre Fabre, Sairopa BV, SkylineDX BV, Trained ImmunoTherapeutics Discovery and has Equity in IO Biotech, Sairopa BV and SkylineDX BV. MVH received honoraria from MSD, BMS, Roche, Novartis, Sun Pharma, Sanofi, Almirall, Biofrontera, Galderma, Immunocore, InfectoPharm. CG is on the advisory board or has received honoraria from Almirall, Amgen, Beiersdorf, BioNTech, Bristol-Myers Squibb, Immunocore, Janssen, MSD Sharp & Dohme, Novartis, Pierre-Fabre Pharma, Regeneron, Roche, Sanofi Genzyme, SUN Pharma and Sysmex, research funding from Bristol-Myers Squibb, Novartis, Regeneron and Sanofi, outside the submitted work. C.G. is co-founder of Dermagnostix and Dermagnostix R&D. All remaining authors have declared no conflicts of interest., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

The introduction of immune checkpoint blockade (ICB) has markedly improved outcomes for advanced melanoma. However, many patients develop resistance through unknown mechanisms. While combination ICB has improved response rate and progression-free survival, it substantially increases toxicity. Biomarkers to distinguish patients who would benefit from combination therapy versus aPD-1 remain elusive. We analyzed whole-exome sequencing of pretreatment tumors from four cohorts ( n = 140) of ICB-naïve patients treated with aPD-1. High genomic heterogeneity and low ploidy robustly identified patients intrinsically resistant to aPD-1. To establish clinically actionable predictions, we optimized and validated a predictive model using ploidy and heterogeneity to confidently identify (90% PPV) patients with intrinsic resistance to and worse survival on aPD-1. We further observed that three of seven (43%) patients predicted to be intrinsically resistant to single-agent PD-1 ICB responded to combination ICB, suggesting that these patients may benefit disproportionately from combination ICB. These findings highlight the importance of heterogeneity and ploidy, nominating an approach toward clinical actionability.

Loss of proteostasis is a hallmark of aging and Alzheimer disease (AD). We identify β-hydroxybutyrate (βHB), a ketone body, as a regulator of protein solubility. βHB primarily provides ATP substrate during periods of reduced glucose availability, and regulates other cellular processes through protein interactions. We demonstrate βHB-induced protein insolubility is not dependent on covalent protein modification, pH, or solute load, and is observable in mouse brain in vivo after delivery of a ketone ester. This mechanism is selective for pathological proteins such as amyloid-β, and exogenous βHB ameliorates pathology in nematode models of amyloid-β aggregation toxicity. We generate libraries of the βHB-induced protein insolublome using mass spectrometry proteomics, and identify common protein domains and upstream regulators. We show enrichment of neurodegeneration-related proteins among βHB targets and the clearance of these targets from mouse brain. These data indicate a metabolically regulated mechanism of proteostasis relevant to aging and AD., Competing Interests: Declaration of interests J.C.N. and E.V. hold patents related to molecules described herein, licensed to BHB Therapeutics Ltd and Selah Therapeutics Ltd. J.C.N. and E.V. are co-founders with stock holdings, and BJS holds stock options, in BHB Therapeutics. J.C.N., E.V., and B.S. are co-founders with stock holdings in Selah Therapeutics., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Cells are subjected to dynamic mechanical environments which impart forces and induce cellular responses. In age-related conditions like pulmonary fibrosis, there is both an increase in tissue stiffness and an accumulation of senescent cells. While senescent cells produce a senescence-associated secretory phenotype (SASP), the impact of physical stimuli on both cellular senescence and the SASP is not well understood. Here, we show that mechanical tension, modeled using cell culture substrate rigidity, influences senescent cell markers like SA-β-gal and secretory phenotypes. Comparing human primary pulmonary fibroblasts (IMR-90) cultured on physiological (2 kPa), fibrotic (50 kPa), and plastic (approximately 3 GPa) substrates, followed by senescence induction using doxorubicin, we identified unique high-stiffness-driven secretory protein profiles using mass spectrometry and transcriptomic signatures, both showing an enrichment in collagen proteins. Consistently, clusters of p21+ cells are seen in fibrotic regions of bleomycin induced pulmonary fibrosis in mice. Computational meta-analysis of single-cell RNA sequencing datasets from human interstitial lung disease confirmed these stiffness SASP genes are highly expressed in disease fibroblasts and strongly correlate with mechanotransduction and senescence-related pathways. Thus, mechanical forces shape cell senescence and their secretory phenotypes.

This study investigated whether adjuvant treatments in stage III cutaneous melanoma (CM) influenced patterns of recurrence. Patients with primary (n = 1033) or relapsed CM (n = 350) who received adjuvant therapies with Nivolumab (N), Pembrolizumab (P), or Dabrafenib and Trametinib (D + T) were extracted from the prospective multicenter real-world skin cancer registry ADOReg. Endpoints were progression-free survival (PFS), distant metastasis-free survival (DMFS), organ-specific DMFS, and overall survival (OS). For primary cases, D + T indicated an improved PFS (1- and 2-year PFS: 90.9%; 82.7%) as compared to P (81.0%, 73.9%; p = .0208), or N (83.8%, 75.2%; p = .0539). BRAF-mutated(mut) CM demonstrated significantly lower PFS (p = .0022) and decreased DMFS (p = .0580) when treated with immune checkpoint inhibitor (ICI) instead of D + T. Besides, NRAS-mut CM tended to perform worse than wt CM upon ICI (PFS: p = .1349; DMFS: p = .0540). OS was similar between the groups. Relapsed cases showed decreased PFS, DMFS, and OS in comparison to primary (all: p < .001), without significant differences between the subgroups. Organ-specific DMFS was significantly altered for primary cases with bone (p = .0367) or brain metastases (p = .0202). In relapsed CM, the frequency of liver (D + T: 1.5%; P: 12%; N: 9%) and LN metastases (D + T: 1.5%; P: 12%; N: 10.2%) was significantly lower with adjuvant D + T than ICI. NRAS-mut CM showed increased recurrence in primary and relapsed cases. These data show that adjuvant D + T is superior to ICI in primary BRAF-mut CM., (© 2024 The Author(s). International Journal of Cancer published by John Wiley & Sons Ltd on behalf of UICC.)

Replicative errors, inefficient repair, and proximity to sites of reactive oxygen species production make mitochondrial DNA (mtDNA) susceptible to damage with time. We explore in vivo allotopic expression (re-engineering mitochondrial genes and expressing them from the nucleus) as an approach to rescue defects arising from mtDNA mutations. We used a mouse strain C57BL/6J(mtFVB) with a natural polymorphism (m.7778 G>T) in the mitochondrial ATP8 gene that encodes a protein subunit of the ATP synthase. We generated a transgenic mouse with an epitope-tagged recoded mitochondrial-targeted ATP8 gene expressed from the ROSA26 locus in the nucleus and used the C57BL/6J(mtFVB) strain to verify successful incorporation. The allotopically expressed ATP8 protein in transgenic mice was constitutively expressed across all tested tissues, successfully transported into the mitochondria, and incorporated into ATP synthase. The ATP synthase with transgene had similar activity to non-transgenic control, suggesting successful integration and function. Exogenous ATP8 protein had no negative impact on measured mitochondrial function, metabolism, or behavior. Successful allotopic expression of a mitochondrially encoded protein in vivo in a mammal is a step toward utilizing allotopic expression as a gene therapy in humans to repair physiological consequences of mtDNA defects that may accumulate in congenital mitochondrial diseases or with age., Competing Interests: A patent application has been filed on the "Allotopic expression of mtDNA genes" in 2023 in the USA (PCT/US23/76302) (B.D. and A.B.). The authors declare no other competing interests., (© 2024 The Authors.)

Proximal tubular epithelial cells (PTECs) are particularly vulnerable to acute kidney injury (AKI). While fatty acids are the preferred energy source for PTECs via fatty acid oxidation (FAO), FAO-mediated H 2 O 2 production in mitochondria has been shown to be a major source of oxidative stress. We have previously shown that a mitochondrial flavoprotein, long-chain acyl-CoA dehydrogenase (LCAD), which catalyzes a key step in mitochondrial FAO, directly produces H 2 O 2 in vitro . Further we have established that loss of a lysine deacylase, Sirtuin 5 ( Sirt5 -/- ), induces hypersuccinylation and inhibition of mitochondrial FAO genes to stimulate peroxisomal FAO and to protect against AKI. However, the role of LCAD has yet to be determined. Mass spectrometry data acquisition revealed that LCAD is hypersuccinylated in Sirt5 -/- kidneys after AKI. Following two distinct models of AKI, cisplatin treatment or renal ischemia/reperfusion (IRI), LCAD knockout mice ( LCAD -/- ) demonstrated renoprotection against AKI. Specifically, LCAD -/- kidneys displayed mitigated renal tubular injury, decreased oxidative stress, preserved mitochondrial function, enhanced peroxisomal FAO, and decreased ferroptotic cell death. LCAD deficiency confers protection against two distinct models of AKI. This suggests a therapeutically attractive mechanism whereby preserved mitochondrial respiration as well as enhanced peroxisomal FAO by loss of LCAD mediates renoprotection against AKI.

Competing Interests: Conflicts of interest None to declare.

Biomarkers of aging (BOA) are quantitative parameters that predict biological age and ideally its changes in response to interventions. In recent years, many promising molecular and omic BOA have emerged with an enormous potential for translational geroscience and improving healthspan. However, clinical translation remains limited, in part due to the gap between preclinical research and the application of BOA in clinical research and other translational settings. We surveyed experts in these areas to better understand current challenges for the translation of aging biomarkers. We identified six key barriers to clinical translation and developed guidance for the field to overcome them. Core recommendations include linking BOA to clinically actionable insights, improving affordability and availability to broad populations and validation of biomarkers that are robust and responsive at the level of individuals. Our work provides key insights and practical recommendations to overcome barriers impeding clinical translation of BOA., (© 2024. Springer Nature America, Inc.)

Loss of proteostasis is a highly conserved feature of aging across model organisms and results in the accumulation of insoluble protein aggregates. Protein insolubility is also a unifying feature of major age-related neurodegenerative diseases, including Alzheimer's Disease (AD), in which hundreds of insoluble proteins associate with aggregated amyloid beta (Aβ) in senile plaques. Despite the connection between aging and AD risk, therapeutic approaches to date have overlooked aging-driven generalized protein insolubility as a contributing factor. However, proteins that become insoluble during aging in model organisms are capable of accelerating Aβ aggregation in vitro and lifespan in vivo. Here, using an unbiased proteomics approach, we questioned the relationship between Aβ and age-related protein insolubility. Specifically, we uncovered that Aβ expression drives proteome-wide protein insolubility in C. elegans, even in young animals, and this insoluble proteome is highly similar to the insoluble proteome driven by normal aging, this vulnerable sub-proteome we term the core insoluble proteome (CIP). We show that the CIP is enriched with proteins that modify Aβ toxicity in vivo, suggesting the possibility of a vicious feedforward cycle in the context of AD. Importantly, using human genome-wide association studies (GWAS), we show that the CIP is replete with biological processes implicated not only in neurodegenerative diseases but also across a broad array of chronic, age-related diseases (CARDs). This provides suggestive evidence that age-related loss of proteostasis could play a role in general CARD risk. Finally, we show that the geroprotective, gut-derived metabolite, Urolithin A, relieves Aβ toxicity, supporting its use in clinical trials for dementia and age-related diseases., (© 2024. The Author(s).)

Immunotherapy has achieved tremendous success in melanoma. However, only around 50% of advanced melanoma patients benefit from immunotherapy. Cyclin-dependent kinase inhibitor 2A (CDKN2A), encoding the two tumor-suppressor proteins p14 ARF and p16 INK4a , belongs to the most frequently inactivated gene loci in melanoma and leads to decreased T cell infiltration. While the role of p16 INK4a has been extensively investigated, knowledge about p14 ARF in melanoma is scarce. In this study, we elucidate the impact of reduced p14 ARF expression on melanoma immunogenicity. Knockdown of p14 ARF in melanoma cell lines diminished their recognition and killing by melanoma differentiation antigen (MDA)-specific T cells. Resistance was caused by a reduction of the peptide surface density of presented MDAs. Immunopeptidomic analyses revealed that antigen presentation via human leukocyte antigen class I (HLA-I) molecules was enhanced upon p14 ARF downregulation in general, but absolute and relative expression of cognate peptides was decreased. However, this phenotype is associated with a favorable outcome for melanoma patients. Limiting Wnt5a signaling reverted this phenotype, suggesting an involvement of non-canonical Wnt signaling. Taken together, our data indicate a new mechanism limiting MDA-specific T cell responses by decreasing both absolute and relative MDA-peptide presentation in melanoma., (© 2024 The Authors. Molecular Oncology published by John Wiley & Sons Ltd on behalf of Federation of European Biochemical Societies.)

Cellular senescence is a major driver of aging and age-related diseases. Quantification of senescent cells remains challenging due to the lack of senescence-specific markers and generalist, unbiased methodology. Here, we describe the Fully-Automated Senescence Test (FAST), an image-based method for the high-throughput, single-cell assessment of senescence in cultured cells. FAST quantifies three of the most widely adopted senescence-associated markers for each cell imaged: senescence-associated β-galactosidase activity (SA-β-Gal) using X-Gal, proliferation arrest via lack of 5-ethynyl-2'-deoxyuridine (EdU) incorporation, and enlarged morphology via increased nuclear area. The presented workflow entails microplate image acquisition, image processing, data analysis, and graphing. Standardization was achieved by (i) quantifying colorimetric SA-β-Gal via optical density; (ii) implementing staining background controls; and (iii) automating image acquisition, image processing, and data analysis. In addition to the automated threshold-based scoring, a multivariate machine learning approach is provided. We show that FAST accurately quantifies senescence burden and is agnostic to cell type and microscope setup. Moreover, it effectively mitigates false-positive senescence marker staining, a common issue arising from culturing conditions. Using FAST, we compared X-Gal with fluorescent C 12 FDG live-cell SA-β-Gal staining on the single-cell level. We observed only a modest correlation between the two, indicating that those stains are not trivially interchangeable. Finally, we provide proof of concept that our method is suitable for screening compounds that modify senescence burden. This method will be broadly useful to the aging field by enabling rapid, unbiased, and user-friendly quantification of senescence burden in culture, as well as facilitating large-scale experiments that were previously impractical., (© 2024. The Author(s).)

The fallopian tubes play key roles in processes from pregnancy to ovarian cancer where three-dimensional (3D) cellular and extracellular interactions are important to their pathophysiology. Here, we develop a 3D multicompartment assembloid model of the fallopian tube that molecularly, functionally, and architecturally resembles the organ. Global label-free proteomics, innovative assays capturing physiological functions of the fallopian tube (i.e., oocyte transport), and whole-organ single-cell resolution mapping are used to validate these assembloids through a multifaceted platform with direct comparisons to fallopian tube tissue. These techniques converge at a unique combination of assembloid parameters with the highest similarity to the reference fallopian tube. This work establishes (i) an optimized model of the human fallopian tubes for in vitro studies of their pathophysiology and (ii) an iterative platform for customized 3D in vitro models of human organs that are molecularly, functionally, and microanatomically accurate by combining tunable assembloid and tissue mapping methods.

Sirtuin-2 (Sirt2), an NAD+-dependent lysine deacylase enzyme, has previously been implicated as a regulator of glucose metabolism, but the specific mechanisms remain poorly defined. Here, we observed that Sirt2-/- males, but not females, have decreased body fat, moderate hypoglycemia upon fasting, and perturbed glucose handling during exercise compared to wild type controls. Conversion of injected lactate, pyruvate, and glycerol boluses into glucose via gluconeogenesis was impaired, but only in males. Primary Sirt2-/- male hepatocytes exhibited reduced glycolysis and reduced mitochondrial respiration. RNAseq and proteomics were used to interrogate the mechanisms behind this liver phenotype. Loss of Sirt2 did not lead to transcriptional dysregulation, as very few genes were altered in the transcriptome. In keeping with this, there were also negligible changes to protein abundance. Site-specific quantification of the hepatic acetylome, however, showed that 13% of all detected acetylated peptides were significantly increased in Sirt2-/- male liver versus wild type, representing putative Sirt2 target sites. Strikingly, none of these putative target sites were hyperacetylated in Sirt2-/- female liver. The target sites in the male liver were distributed across mitochondria (44%), cytoplasm (32%), nucleus (8%), and other compartments (16%). Despite the high number of putative mitochondrial Sirt2 targets, Sirt2 antigen was not detected in purified wild type liver mitochondria, suggesting that Sirt2's regulation of mitochondrial function occurs from outside the organelle. We conclude that Sirt2 regulates hepatic protein acetylation and metabolism in a sex-specific manner.

Background: Early detection of melanoma, a potentially lethal type of skin cancer with high prevalence worldwide, improves patient prognosis. In retrospective studies, artificial intelligence (AI) has proven to be helpful for enhancing melanoma detection. However, there are few prospective studies confirming these promising results. Existing studies are limited by low sample sizes, too homogenous datasets, or lack of inclusion of rare melanoma subtypes, preventing a fair and thorough evaluation of AI and its generalizability, a crucial aspect for its application in the clinical setting., Methods: Therefore, we assessed "All Data are Ext" (ADAE), an established open-source ensemble algorithm for detecting melanomas, by comparing its diagnostic accuracy to that of dermatologists on a prospectively collected, external, heterogeneous test set comprising eight distinct hospitals, four different camera setups, rare melanoma subtypes, and special anatomical sites. We advanced the algorithm with real test-time augmentation (R-TTA, i.e., providing real photographs of lesions taken from multiple angles and averaging the predictions), and evaluated its generalization capabilities., Results: Overall, the AI shows higher balanced accuracy than dermatologists (0.798, 95% confidence interval (CI) 0.779-0.814 vs. 0.781, 95% CI 0.760-0.802; p = 4.0e-145), obtaining a higher sensitivity (0.921, 95% CI 0.900-0.942 vs. 0.734, 95% CI 0.701-0.770; p = 3.3e-165) at the cost of a lower specificity (0.673, 95% CI 0.641-0.702 vs. 0.828, 95% CI 0.804-0.852; p = 3.3e-165)., Conclusion: As the algorithm exhibits a significant performance advantage on our heterogeneous dataset exclusively comprising melanoma-suspicious lesions, AI may offer the potential to support dermatologists, particularly in diagnosing challenging cases., (© 2024. The Author(s).)

Chemotherapy poses both physical and psychological challenges for patients, prompting many to seek answers independently through online resources. This study investigates German Google search behavior regarding chemotherapy-related terms using Google AdWords data from September 2018 to September 2022 to gain insights into patient concerns and needs. A total of 1461 search terms associated with "chemotherapy" were identified, representing 1,749,312 to 28,958,400 search queries. These terms were categorized into four groups based on frequency and analyzed. Queries related to "adjuvant" and "neoadjuvant" chemotherapy, as well as "immunotherapy", suggest potential confusion among patients. Breast cancer emerged as the most searched tumor type, with hair loss, its management, and dermatological issues being the most searched side effects. These findings underscore the role of search engines such as Google in facilitating access to healthcare information and provide valuable insights into patient thoughts and needs. Healthcare providers can leverage this information to deliver patient-centric care and optimize treatment outcomes.

(-)-Ambrox, the most prominent olfactive component of ambergris, is one of the most widely used biodegradable fragrance ingredients. It is traditionally produced from the diterpene sclareol chemically modified and cyclized into (-)-ambrox. The availability of the new feedstock (E)-β-farnesene produced by fermentation opened new routes to (E,E)-homofarnesol as a precursor to (-)-ambrox. Combining the chemical transformation of (E)-β-farnesene to (E,E)-homofarnesol and its enzymatic cyclization with an engineered Squalene Hopene Cyclase provided a new sustainable route for the production of (-)-ambrox at industrial scale. Compared to the traditional synthesis from sclareol, the new and innovative route from (E)-β-farnesene improves atom and step economy, reduces waste production, solvent and energy consumption., (Copyright 2024 Eric Eichhorn, Boris Schilling, Agnes Bombrun, Fridtjof Schroeder. License: This work is licensed under a Creative Commons Attribution 4.0 International License.)

Objectives: Chondrocyte metabolic dysfunction plays an important role in osteoarthritis (OA) development during aging and obesity. Protein post-translational modifications (PTMs) have recently emerged as an important regulator of cellular metabolism. We aim to study one type of PTM, lysine malonylation (MaK) and its regulator Sirt5 in OA development., Methods: Human and mouse cartilage tissues were used to measure SIRT5 and MaK levels. Both systemic and cartilage-specific conditional knockout mouse models were subject to high-fat diet (HFD) treatment to induce obesity and OA. Proteomics analysis was performed in Sirt5 -/- and WT chondrocytes. SIRT5 mutation was identified in the Utah Population Database (UPDB)., Results: We found that SIRT5 decreases while MAK increases in the cartilage during aging. A combination of Sirt5 deficiency and obesity exacerbates joint degeneration in a sex dependent manner in mice. We further delineate the malonylome in chondrocytes, pinpointing MaK's predominant impact on various metabolic pathways such as carbon metabolism and glycolysis. Lastly, we identified a rare coding mutation in SIRT5 that dominantly segregates in a family with OA. The mutation results in substitution of an evolutionally invariant phenylalanine (Phe-F) to leucine (Leu-L) (F101L) in the catalytic domain. The mutant protein results in higher MaK level and decreased expression of cartilage ECM genes and upregulation of inflammation associated genes., Conclusions: We found that Sirt5 mediated MaK is an important regulator of chondrocyte cellular metabolism and dysregulation of Sirt5-MaK could be an important mechanism underlying aging and obesity associated OA development.

Osteoarthritis (OA) of the knee is a degenerative condition of the skeletal extracellular matrix (ECM) marked by the loss of articular cartilage and subchondral bone homeostasis. Treatments for OA in the knee beyond full joint replacement are lacking primarily due to gaps in molecular knowledge of the biological drivers of disease. Here, Mass Spectrometry Imaging (MSI) enabled molecular spatial mapping of the proteomic landscape of human knee tissues. Histologic sections of human tibial plateaus from OA patients and cadaveric controls were treated with collagenase III to target ECM proteins prior to imaging using a timsTOF fleX mass spectrometer (Bruker) for matrix-assisted laser desorption ionization (MALDI)-MSI of bone and cartilage proteins in human knees. Spatial MSI data of the knee, using sections of the tibial plateau from non-arthritic, cadaveric donors or from knee replacement patients with medial OA were processed and automatically segmented identifying distinct areas of joint damage. ECM peptide markers compared either OA to cadaveric tissues or OA medial to OA lateral. Not only did candidate peptides distinguish OA relative to intact cartilage, but also emphasized a significant spatial difference between OA and intact subchondral bone (AUROC >0.85). Overall, 31 peptide candidates from ECM proteins, including COL1A1, COL3A1, and unanticipated detection of collagens COL6A1 and COL6A3 in adult bone, exhibited significantly elevated abundance in diseased tissue. Highly specific hydroxyproline-containing collagens dominated OA subchondral bone directly under regions of lost cartilage revealing dramatic tissue remodeling providing molecular details on the progression of joint degeneration in OA. The identification of specific spatial markers for the progression of subchondral bone degeneration in OA advances our molecular understanding of coupled deterioration of joint tissues.

Competing Interests: Conflicts of interest Dr Utikal is on the advisory board or has received honoraria from Amgen, Bristol Myers Squibb, GSK, Immunocore, LeoPharma, Merck Sharp and Dohme, Novartis, Pierre Fabre, Roche, and Sanofi outside the submitted work. Dr Meier has received speaker's fees or/and advisor's honoraria from Novartis, Roche, BMS, MSD, and Pierre Fabre. Dr Hobelsberger reports speaker's honoraria from Almirall, UCB, and AbbVie. Dr Gellrich has received speaker's fees or/and advisor's honoraria by Sun Pharma, Sanofi, and Merck. Dr Hauschild reports speaker's honoraria or consultancy fees from the following companies: Agenus, Amgen, BMS, Dermagnostix, Highlight Therapeutics, Immunocore, Incyte, IO Biotech, MerckPfizer, MSD, NercaCare, Novartis, Philogen, Pierre Fabre, Regeneron, Roche, Sanofi-Genzyme, Seagen, Sun Pharma, and Xenthera, outside the submitted work. Dr French is on the advisory board or has received consulting/speaker honoraria from for Galderma, Janssen, Leo Pharma, Eli Lilly, Almirall, Union Therapeutics, Regeneron, Novartis, Amgen, Abbvie, UCB, Biotest, and InflaRx. Dr Schlaak has received consultant or speaker fees or travel grants from BMS, MSD, Roche, Kyowa Kirin, Novartis, Sanofi Genzyme, Pierre Fabre, Sun Pharma, and Immunocore. Dr Erdmann declares honoraria from Bristol-Meyers Squibb, Immunocore, and Novartis outside the submitted work. Dr Haferkamp reports advisory roles for or has received honoraria from Pierre Fabre Pharmaceuticals, Novartis, Roche, BMS, Amgen, and MSD outside the submitted work. Dr Drexler has received honoraria from Pierre Fabre Pharmaceuticals and Novartis outside the submitted work. Dr Sondermann reports grants, speaker's honoraria, or consultancy fees from medi GmbH Bayreuth, Abbvie, Almirall, Amgen, Bristol-Myers Squibb, Celgene, GSK, Janssen, LEO Pharma, Lilly, MSD, Novartis, Pfizer, Roche, Sanofi Genzyme, and UCB outside the submitted work. Dr Schilling reports advisory roles for or has received honoraria from Pierre Fabre Pharmaceuticals, Incyte, Novartis, Roche, BMS, and MSD. Dr Goebeler has received speaker's honoraria and/or has served as a consultant and/or member of advisory boards for Almirall, Argenx, Biotest, Eli Lilly, Janssen Cilag, Leo Pharma, Novartis, and UCB, outside the submitted work. Dr Kather reports consulting services for Owkin, France, Panakeia, UK, and DoMore Diagnostics, Norway and has received honoraria for lectures by MSD, Eisai, and Fresenius. Dr Brinker reports owning a company that develops mobile apps (Smart Health Heidelberg GmbH, Handschuhsheimer Landstr. 9/1, 69120 Heidelberg). Author Haggenmüller, Author Maron, Author Hekler, Dr Krieghoff-Henning, Dr Gaiser, Dr Müller, Dr Fabian, Dr Sergon, Dr Weichenthal, Dr Heinzerling, Dr Schlager, Dr Ghoreschi, Dr Hilke, Dr Pochi, Dr Korsing, Dr Berking, Dr Heppt, Dr Schadendorf, Dr Fröhling, Author Kaminski, Author Doppler, and Author Bucher have no conflicts of interest to declare.

Alzheimer's disease (AD) and Alzheimer's related diseases (ADRD) are prevalent age-related neurodegenerative disorders characterized by the accumulation of amyloid-β (Aβ) plaques and Tau neurofibrillary tangles. The nematode Caenorhabditis elegan s ( C. elegans ) serves as an invaluable model organism in diseases of old age-due to its rapid aging. Here we performed an unbiased systems analysis of a C. elegans strain expressing both Aβ and Tau proteins within neurons. We set out to determine if there was a phenotypic interaction between Aβ and Tau. In addition, we were interested in determining the temporal order of the phenotypic and multi-omic (geromic) outcomes. At an early stage of adulthood, we observed reproductive impairments and mitochondrial dysfunction consistent with disruptions in mRNA transcript abundance, protein solubility, and metabolite levels. Notably, the expression of these neurotoxic proteins exhibited a synergistic effect, leading to accelerated aging. Our findings shed light on the close relationship between normal aging and ADRD. Specifically, we demonstrate alterations to metabolic functions preceding age-related neurotoxicity, offering a resource for the development of new therapeutic strategies.

Acute kidney injury (AKI) is extremely prevalent among hospitalizations and presents a significant risk for the development of chronic kidney disease and increased mortality. Ischemia caused by shock, trauma, and transplant are common causes of AKI. To attenuate ischemic AKI therapeutically, we need a better understanding of the physiological and cellular mechanisms underlying damage. Instances of ischemia are most damaging in proximal tubule epithelial cells (PTECs) where hypoxic signaling cascades, and perhaps more rapidly, posttranslational modifications (PTMs), act in concert to change cellular metabolism. Here, we focus on the effects of the understudied PTM, lysine succinylation. We have previously shown a protective effect of protein hypersuccinylation on PTECs after depletion of the desuccinylase sirtuin5. General trends in the results suggested that hypersuccinylation led to upregulation of peroxisomal activity and was protective against kidney injury. Included in the list of changes was the Parkinson's-related deglycase Park7. There is little known about any links between peroxisome activity and Park7. In this study, we show in vitro and in vivo that Park7 has a crucial role in protection from AKI and upregulated peroxisome activity. These data in combination with published results of Park7's protective role in cardiovascular damage and chronic kidney disease lead us to hypothesize that succinylation of Park7 may ameliorate oxidative damage resulting from AKI and prevent disease progression. This novel mechanism provides a potential therapeutic mechanism that can be targeted. NEW & NOTEWORTHY Succinylation is an understudied posttranslational modification that has been shown to increase peroxisomal activity. Furthermore, increased peroxisomal activity has been shown to reduce oxidative stress and protect proximal tubules after acute kidney injury. Analysis of mass spectrometry succinylomic and proteomic data reveals a novel role for Parkinson's related Park7 in mediating Nrf2 antioxidant response after kidney injury. This novel protection pathway provides new insights for kidney injury prevention and development of novel therapeutics.

Cellular senescence has been strongly linked to aging and age-related diseases. It is well established that the phenotype of senescent cells is highly heterogeneous and influenced by their cell type and senescence-inducing stimulus. Recent single-cell RNA-sequencing studies identified heterogeneity within senescent cell populations. However, proof of functional differences between such subpopulations is lacking. To identify functionally distinct senescent cell subpopulations, we employed high-content image analysis to measure senescence marker expression in primary human endothelial cells and fibroblasts. We found that G2-arrested senescent cells feature higher senescence marker expression than G1-arrested senescent cells. To investigate functional differences, we compared IL-6 secretion and response to ABT263 senolytic treatment in G1 and G2 senescent cells. We determined that G2-arrested senescent cells secrete more IL-6 and are more sensitive to ABT263 than G1-arrested cells. We hypothesize that cell cycle dependent DNA content is a key contributor to the heterogeneity within senescent cell populations. This study demonstrates the existence of functionally distinct senescent subpopulations even in culture. This data provides the first evidence of selective cell response to senolytic treatment among senescent cell subpopulations. Overall, this study emphasizes the importance of considering the senescent cell heterogeneity in the development of future senolytic therapies.

Senescence emerged as a significant mechanism of aging and age-related diseases, offering an attractive target for clinical interventions. Senescent cells release a senescence-associated secretory phenotype (SASP), including exosomes that may act as signal transducers between distal tissues, propagating secondary or bystander senescence and signaling throughout the body. However, the composition of exosome SASP remains underexplored, presenting an opportunity for novel unbiased discovery. Here, we present a detailed proteomic and lipidomic analysis of exosome SASP using mass spectrometry from human plasma from young and older individuals and from tissue culture of senescent primary human lung fibroblasts. We identified ~1,300 exosome proteins released by senescent fibroblasts induced by three different senescence inducers causing most exosome proteins to be differentially regulated with senescence. In parallel, a human plasma cohort from young and old individuals revealed over 1,350 exosome proteins and 171 plasma exosome proteins were regulated when comparing old vs young individuals. Of the age-regulated plasma exosome proteins, we observed 52 exosome SASP factors that were also regulated in exosomes from the senescent fibroblasts, including serine protease inhibitors (SERPINs), Prothrombin, Coagulation factor V, Plasminogen, and Reelin. In addition, 247 lipids were identified with high confidence in all exosome samples. Following the senescence inducers, a majority of the identified phosphatidylcholine, phosphatidylethanolamine, and sphingomyelin species increased significantly indicating cellular membrane changes. The most notable categories of significantly changed proteins were related to extracellular matrix remodeling and inflammation, both potentially detrimental pathways that can damage surrounding tissues and even induce secondary or bystander senescence. Our findings reveal mechanistic insights and potential senescence biomarkers, enabling a better approach to surveilling the senescence burden in the aging population and offering promising therapeutic targets for interventions.

Lysine malonylation is a protein posttranslational modification. We present a protocol to generate stable gene-knockdown K562 cell lines through lentiviral infection of a CRISPR interference (CRISPRi) system followed by lysine malonylation measurement using mass spectrometry (MS). We detail guide RNA (gRNA) vector cloning, lentiviral infection, cell line purification, protein digestion, malonyl-lysine enrichment, desalting, and MS acquisition and analysis. For complete details on the use and execution of this protocol, please refer to Zhang et al. 1 and Bons et al. 2 ., Competing Interests: Declaration of interests E.V. is a scientific co-founder of Napa Therapeutics and serves on the scientific advisory board of Seneque., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Aging compromises brain function leading to cognitive decline. A cyclic ketogenic diet (KD) improves memory in aged mice after long-term administration; however, short-term effects later in life and the molecular mechanisms that govern such changes remain unclear. Here, we explore the impact of a short-term KD treatment starting at elderly stage on brain function of aged mice. Behavioral testing and long-term potentiation (LTP) recordings reveal that KD improves working memory and hippocampal LTP. Furthermore, the synaptosome proteome of aged mice fed a KD long-term evidence changes predominantly at the presynaptic compartment associated to the protein kinase A (PKA) signaling pathway. These findings were corroborated in vivo by western blot analysis, with high BDNF abundance and PKA substrate phosphorylation. Overall, we show that a KD modifies brain function even when it is administered later in life and recapitulates molecular features of long-term administration, including the PKA signaling pathway, thus promoting synaptic plasticity at advanced age., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

During cellular senescence, persistent growth arrest and changes in protein expression programs are accompanied by a senescence-associated secretory phenotype (SASP). In this study, we detected the upregulation of the SASP-related protein dipeptidyl peptidase 4 (DDP4) in human primary lung cells rendered senescent by exposure to ionizing radiation. DPP4 is an exopeptidase that plays a crucial role in the cleavage of various proteins, resulting in the loss of N-terminal dipeptides and proinflammatory effects. Interestingly, our data revealed an association between severe coronavirus disease 2019 (COVID-19) and DDP4, namely that DPP4 levels increased in the plasma of patients with COVID-19 and were correlated with age and disease progression. Although we could not determine the direct effect of DDP4 on viral replication, mechanistic studies in cell culture revealed a negative impact on the expression of the tight junction protein zonula occludens-1 (ZO-1), which contributes to epithelial barrier function. Mass spectrometry analysis indicated that DPP4 overexpressing cells exhibited a decrease in ZO-1 and increased expression of pro-inflammatory cytokines and chemokines. By investigating the effect of DPP4 on the barrier function of human primary cells, we detected an increase in ZO-1 using DPP4 inhibitors. These results provide an important contribution to our understanding of DPP4 in the context of senescence, suggesting that DPP4 plays a major role as part of the SASP. Our results provide evidence that cellular senescence, a hallmark of aging, has an important impact on respiratory infections.

Elevated levels of peripheral blood and tumor tissue neutrophils are associated with poorer clinical response and therapy resistance in melanoma. The underlying mechanism and the role of neutrophils in targeted therapy is still not fully understood. Serum samples of patients with advanced melanoma were collected and neutrophil-associated serum markers were measured and correlated with response to targeted therapy. Blood neutrophils from healthy donors and patients with advanced melanoma were isolated, and their phenotypes, as well as their in vitro functions, were compared. In vitro functional tests were conducted through nonadherent cocultures with melanoma cells. Protection of melanoma cell lines by neutrophils was assessed under MAPK inhibition. Blood neutrophils from advanced melanoma patients exhibited lower CD16 expression compared to healthy donors. In vitro, both healthy-donor- and patient-derived neutrophils prevented melanoma cell apoptosis upon dual MAPK inhibition. The effect depended on cell-cell contact and melanoma cell susceptibility to treatment. Interference with protease activity of neutrophils prevented melanoma cell protection during treatment in cocultures. The negative correlation between neutrophils and melanoma outcomes seems to be linked to a protumoral function of neutrophils. In vitro, neutrophils exert a direct protective effect on melanoma cells during dual MAPK inhibition. This study further hints at a crucial role of neutrophil-related protease activity in protection.

Competing Interests: Conflicts of interest Jochen S. Utikal is on the advisory board or has received honoraria and travel support from Amgen, Bristol Myers Squibb, GSK, Immunocore, LeoPharma, Merck Sharp and Dohme, Novartis, Pierre Fabre, Roche and Sanofi outside the submitted work. Friedegund Meier has received travel support and/or speaker's fees and/or advisor's honoraria by Novartis, Roche, BMS, MSD and Pierre Fabre and research funding from Novartis and Roche. Sarah Hobelsberger reports clinical trial support from Almirall and speaker's honoraria from Almirall, UCB and AbbVie and has received travel support from the following companies: UCB, Janssen Cilag, Almirall, Novartis, Lilly, LEO Pharma and AbbVie outside the submitted work. Sebastian Haferkamp reports advisory roles for or has received honoraria from Pierre Fabre Pharmaceuticals, Novartis, Roche, BMS, Amgen and MSD outside the submitted work. Konstantin Drexler has received honoraria from Pierre Fabre Pharmaceuticals and Novartis. Axel Hauschild reports clinical trial support, speaker's honoraria, or consultancy fees from the following companies: Agenus, Amgen, BMS, Dermagnostix, Highlight Therapeutics, Immunocore, Incyte, IO Biotech, MerckPfizer, MSD, NercaCare, Novartis, Philogen, Pierre Fabre, Regeneron, Roche, Sanofi-Genzyme, Seagen, Sun Pharma and Xenthera outside the submitted work. Lars E. French is on the advisory board or has received consulting/speaker honoraria from Galderma, Janssen, Leo Pharma, Eli Lilly, Almirall, Union Therapeutics, Regeneron, Novartis, Amgen, AbbVie, UCB, Biotest and InflaRx. Max Schlaak reports advisory roles for Bristol-Myers Squibb, Novartis, MSD, Roche, Pierre Fabre, Kyowa Kirin, Immunocore and Sanofi-Genzyme. Wiebke Sondermann reports grants, speaker's honoraria, or consultancy fees from medi GmbH Bayreuth, AbbVie, Almirall, Amgen, Bristol-Myers Squibb, Celgene, GSK, Janssen, LEO Pharma, Lilly, MSD, Novartis, Pfizer, Roche, Sanofi Genzyme and UCB outside the submitted work. Bastian Schilling reports advisory roles for or has received honoraria from Pierre Fabre Pharmaceuticals, Incyte, Novartis, Roche, BMS and MSD, research funding from BMS, Pierre Fabre Pharmaceuticals and MSD and travel support from Novartis, Roche, BMS, Pierre Fabre Pharmaceuticals and Amgen outside the submitted work. Matthias Goebeler has received speaker's honoraria and/or has served as a consultant and/or member of advisory boards for Almirall, Argenx, Biotest, Eli Lilly, Janssen Cilag, Leo Pharma, Novartis and UCB outside the submitted work. Michael Erdmann declares honoraria and travel support from Bristol-Meyers Squibb, Immunocore and Novartis outside the submitted work. Jakob N. Kather reports consulting services for Owkin, France, Panakeia, UK and DoMore Diagnostics, Norway and has received honoraria for lectures by MSD, Eisai and Fresenius. Titus J. Brinker reports owning a company that develops mobile apps (Smart Health Heidelberg GmbH, Handschuhsheimer Landstr. 9/1, 69,120 Heidelberg). The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Dicarboxylic fatty acids are generated in the liver and kidney in a minor pathway called fatty acid ω-oxidation. The effects of consuming dicarboxylic fatty acids as an alternative source of dietary fat have not been explored. Here, we fed dodecanedioic acid, a 12-carbon dicarboxylic (DC12), to mice at 20% of daily caloric intake for nine weeks. DC12 increased metabolic rate, reduced body fat, reduced liver fat, and improved glucose tolerance. We observed DC12-specific breakdown products in liver, kidney, muscle, heart, and brain, indicating that oral DC12 escaped first-pass liver metabolism and was utilized by many tissues. In tissues expressing the "a" isoform of acyl-CoA oxidase-1 (ACOX1), a key peroxisomal fatty acid oxidation enzyme, DC12 was chain shortened to the TCA cycle intermediate succinyl-CoA. In tissues with low peroxisomal fatty acid oxidation capacity, DC12 was oxidized by mitochondria. In vitro, DC12 was catabolized even by adipose tissue and was not stored intracellularly. We conclude that DC12 and other dicarboxylic acids may be useful for combatting obesity and for treating metabolic disorders.

Purpose: The objective of this study was to investigate the senescent phenotypes of human corneal endothelial cells (hCEnCs) upon treatment with ultraviolet (UV)-A., Methods: We assessed cell morphology, senescence-associated β-galactosidase (SA-β-gal) activity, cell proliferation and expression of senescence markers ( p16 and p21 ) in hCEnCs exposed to UV-A radiation, and senescent hCEnCs induced by ionizing radiation (IR) were used as positive controls. We performed RNA sequencing and proteomics analyses to compare gene and protein expression profiles between UV-A- and IR-induced senescent hCEnCs, and we also compared the results to non-senescent hCEnCs., Results: Cells exposed to 5 J/cm2 of UV-A or to IR exhibited typical senescent phenotypes, including enlargement, increased SA-β-gal activity, decreased cell proliferation and elevated expression of p16 and p21 . RNA-Seq analysis revealed that 83.9% of the genes significantly upregulated and 82.6% of the genes significantly downregulated in UV-A-induced senescent hCEnCs overlapped with the genes regulated in IR-induced senescent hCEnCs. Proteomics also revealed that 93.8% of the proteins significantly upregulated in UV-A-induced senescent hCEnCs overlapped with those induced by IR. In proteomics analyses, senescent hCEnCs induced by UV-A exhibited elevated expression levels of several factors part of the senescence-associated secretory phenotype., Conclusions: In this study, where senescence was induced by UV-A, a more physiological stress for hCEnCs compared to IR, we determined that UV-A modulated the expression of many genes and proteins typically altered upon IR treatment, a more conventional method of senescence induction, even though UV-A also modulated specific pathways unrelated to IR.

Allogeneic chimeric antigen receptor (CAR) T cell therapies hold the potential to overcome many of the challenges associated with patient-derived (autologous) CAR T cells. Key considerations in the development of allogeneic CAR T cell therapies include prevention of graft-vs-host disease (GvHD) and suppression of allograft rejection. Here, we describe preclinical data supporting the ongoing first-in-human clinical study, the CaMMouflage trial (NCT05722418), evaluating CB-011 in patients with relapsed/refractory multiple myeloma. CB-011 is a hypoimmunogenic, allogeneic anti-B-cell maturation antigen (BCMA) CAR T cell therapy candidate. CB-011 cells feature 4 genomic alterations and were engineered from healthy donor-derived T cells using a Cas12a CRISPR hybrid RNA-DNA (chRDNA) genome-editing technology platform. To address allograft rejection, CAR T cells were engineered to prevent endogenous HLA class I complex expression and overexpress a single-chain polyprotein complex composed of beta-2 microglobulin (B2M) tethered to HLA-E. In addition, T-cell receptor (TCR) expression was disrupted at the TCR alpha constant locus in combination with the site-specific insertion of a humanized BCMA-specific CAR. CB-011 cells exhibited robust plasmablast cytotoxicity in vitro in a mixed lymphocyte reaction in cell cocultures derived from patients with multiple myeloma. In addition, CB-011 cells demonstrated suppressed recognition by and cytotoxicity from HLA-mismatched T cells. CB-011 cells were protected from natural killer cell-mediated cytotoxicity in vitro and in vivo due to endogenous promoter-driven expression of B2M-HLA-E. Potent antitumor efficacy, when combined with an immune-cloaking armoring strategy to dampen allograft rejection, offers optimized therapeutic potential in multiple myeloma. See related Spotlight by Caimi and Melenhorst, p. 385., (©2024 The Authors; Published by the American Association for Cancer Research.)

Introduction: Huntington's disease (HD) is a fatal neurodegenerative disorder caused by an expansion of the CAG trinucleotide repeat in the Huntingtin gene (HTT). Immune activation is abundant in the striatum of HD patients. Detection of active microglia at presymptomatic stages suggests that microgliosis is a key early driver of neuronal dysfunction and degeneration. Recent studies showed that deletion of Tyrobp, a microglial protein, ameliorates neuronal dysfunction in Alzheimer's disease amyloidopathy and tauopathy mouse models while decreasing components of the complement subnetwork., Objective: While TYROBP/DAP12-mediated microglial activation is detrimental for some diseases such as peripheral nerve injury, it is beneficial for other diseases. We sought to determine whether the TYROBP network is implicated in HD and whether Tyrobp deletion impacts HD striatal function and transcriptomics., Methods: To test the hypothesis that Tyrobp deficiency would be beneficial in an HD model, we placed the Q175 HD mouse model on a Tyrobp-null background. We characterized these mice with a combination of behavioral testing, immunohistochemistry, transcriptomic and proteomic profiling. Further, we evaluated the gene signature in isolated Q175 striatal microglia, with and without Tyrobp., Results: Comprehensive analysis of publicly available human HD transcriptomic data revealed that the TYROBP network is overactivated in the HD putamen. The Q175 mice showed morphologic microglial activation, reduced levels of post-synaptic density-95 protein and motor deficits at 6 and 9 months of age, all of which were ameliorated on the Tyrobp-null background. Gene expression analysis revealed that lack of Tyrobp in the Q175 model does not prevent the decrease in the expression of striatal neuronal genes but reduces pro-inflammatory pathways that are specifically active in HD human brain, including genes identified as detrimental in neurodegenerative diseases, e.g. C1q and members of the Ccr5 signaling pathway. Integration of transcriptomic and proteomic data revealed that astrogliosis and complement system pathway were reduced after Tyrobp deletion, which was further validated by immunofluorescence analysis., Conclusions: Our data provide molecular and functional support demonstrating that Tyrobp deletion prevents many of the abnormalities in the HD Q175 mouse model, suggesting that the Tyrobp pathway is a potential therapeutic candidate for Huntington's disease., (© 2024. The Author(s).)

Importance: The development of artificial intelligence (AI)-based melanoma classifiers typically calls for large, centralized datasets, requiring hospitals to give away their patient data, which raises serious privacy concerns. To address this concern, decentralized federated learning has been proposed, where classifier development is distributed across hospitals., Objective: To investigate whether a more privacy-preserving federated learning approach can achieve comparable diagnostic performance to a classical centralized (ie, single-model) and ensemble learning approach for AI-based melanoma diagnostics., Design, Setting, and Participants: This multicentric, single-arm diagnostic study developed a federated model for melanoma-nevus classification using histopathological whole-slide images prospectively acquired at 6 German university hospitals between April 2021 and February 2023 and benchmarked it using both a holdout and an external test dataset. Data analysis was performed from February to April 2023., Exposures: All whole-slide images were retrospectively analyzed by an AI-based classifier without influencing routine clinical care., Main Outcomes and Measures: The area under the receiver operating characteristic curve (AUROC) served as the primary end point for evaluating the diagnostic performance. Secondary end points included balanced accuracy, sensitivity, and specificity., Results: The study included 1025 whole-slide images of clinically melanoma-suspicious skin lesions from 923 patients, consisting of 388 histopathologically confirmed invasive melanomas and 637 nevi. The median (range) age at diagnosis was 58 (18-95) years for the training set, 57 (18-93) years for the holdout test dataset, and 61 (18-95) years for the external test dataset; the median (range) Breslow thickness was 0.70 (0.10-34.00) mm, 0.70 (0.20-14.40) mm, and 0.80 (0.30-20.00) mm, respectively. The federated approach (0.8579; 95% CI, 0.7693-0.9299) performed significantly worse than the classical centralized approach (0.9024; 95% CI, 0.8379-0.9565) in terms of AUROC on a holdout test dataset (pairwise Wilcoxon signed-rank, P < .001) but performed significantly better (0.9126; 95% CI, 0.8810-0.9412) than the classical centralized approach (0.9045; 95% CI, 0.8701-0.9331) on an external test dataset (pairwise Wilcoxon signed-rank, P < .001). Notably, the federated approach performed significantly worse than the ensemble approach on both the holdout (0.8867; 95% CI, 0.8103-0.9481) and external test dataset (0.9227; 95% CI, 0.8941-0.9479)., Conclusions and Relevance: The findings of this diagnostic study suggest that federated learning is a viable approach for the binary classification of invasive melanomas and nevi on a clinically representative distributed dataset. Federated learning can improve privacy protection in AI-based melanoma diagnostics while simultaneously promoting collaboration across institutions and countries. Moreover, it may have the potential to be extended to other image classification tasks in digital cancer histopathology and beyond.

Purpose: The interaction of gut microbiome and immune system is being studied with increasing interest. Disturbing factors, such as antibiotics may impact the immune system via gut and interfere with tumor response to immune checkpoint blockade (ICB)., Methods: In this multicenter retrospective cohort study exclusively treatment-naïve patients with cutaneous or mucosal melanoma treated with first-line anti-PD-1 based ICB for advanced, non-resectable disease between 06/2013 and 09/2018 were included. Progression-free (PFS), and overall survival (OS) according to antibiotic exposure (within 60 days prior to ICB and after the start of ICB vs. no antibiotic exposure) were analyzed. To account for immortal time bias, data from patients with antibiotics during ICB were analyzed separately in the time periods before and after start of antibiotics., Results: Among 578 patients with first-line anti-PD1 based ICB, 7% of patients received antibiotics within 60 days prior to ICB and 19% after starting ICB. Antibiotic exposure prior to ICB was associated with worse PFS (adjusted HR 1.75 [95% CI 1.22-2.52]) and OS (adjusted HR 1.64 [95% CI 1.04-2.58]) by multivariate analysis adjusting for potential confounders. The use of antibiotics after the start of ICB had no effect on either PFS (adjusted HR 1.19; 95% CI 0.89-1.60) or OS (adjusted HR 1.08; 95% CI 0.75-1.57)., Conclusions: Antibiotic exposure within 60 days prior to ICB seems to be associated with worse PFS and OS in melanoma patients receiving first-line anti-PD1 based therapy, whereas antibiotics after the start of ICB do not appear to affect PFS or OS., Competing Interests: Declaration of Competing Interest E.C. received travel support from Bristol-Myers Squibb, Merck Sharp & Dohme, Novartis, UCB and Almirall outside the submitted work. B.S. Honoraria from MSD, BMS, SUN Pharma, Allmiral, Novartis; Advisory Board for MSD, BMS, Pierre Fabre Pharma, Sanofi; travel support from BMS, Novartis, Pierre Fabre Pharma; Research Funding from Novartis; all outside the submitted work. M.S. received speaker honoraria from Novartis and advisory board honoraria from Sanofi Genzyme. R.G. declares research support from Novartis, Amgen, Sanofi, Merck-Serono, Admiral, SUN Pharma and Kyowa-Kirin; honoraria for lectures from Roche Pharma, Bristol-Myers Scuibb, Novartis, MSD. Almirall, Amgen, Merck-Serono, SUN Pharma, Pierre-Fabre, and Sanofi; advisory honoraria from Roche Pharma, Bristol-Myers Squibb, Novartis, MSD, Admiral, Amgen, Pierre-Fabre, Merck-Serono, 4SC, Sun Pharma, Merck-Serono, Sanofi, Delcath and Immunocore. C.L. receives personal fees and travel reimbursement from MSD, BMS, Merck, Sanofi, Almirall Hermal, Kyowa Kirin, Biontech, Pierre Fabre, Novartis and Sun Pharma outside the submitted work. K.K. has served as consultant or/and has received honoraria from Amgen, Roche, Bristol Myers Squibb, Merck Sharp and Dohme, Pierre Fabre and Novartis, and received travel support from Amgen, Merck Sharp and Dohme, Bristol Myers Squibb, Amgen, Pierre Fabre, Medac and Novartis. A.Z.M. received travel support from Novartis, Genzyme, and Bristol-Myers Squibb, outside the submitted work. J.M.P. served as consultant and/or has received honoraria from Bristol-Myers Squibb, Novartis, Sanofi and received travel support from Bristol-Myers Squibb, Novartis, Pierre Fabre and Therakos. E.G. received travel support from Pierre-Fabre, outside the submitted work. A.M. received travel support from Novartis, outside the submitted work. A.R. received grants, personal fees, and non-financial support from Novartis; grants and non-financial support from Bristol-Myers Squibb; personal fees and non-financial support from Roche; personal fees from Merck Sharp & Dohme; and non-financial support from Amgen, outside the submitted work. S.U. declares research support from Bristol Myers Squibb and Merck Serono; speakers and advisory board honoraria from Bristol Myers Squibb, Merck Sharp & Dohme, Merck Serono, and Novartis; and meeting and travel support from Almirall, Bristol-Myers Squibb, IGEA Clinical Biophysics, Merck Sharp & Dohme, Novartis, Pierre Fabre, and Sun Pharma; outside the submitted work. D.S. received grants and other support from Bristol-Myers Squibb, personal fees from Bristol-Myers Squibb during the conduct of the study; personal fees from Amgen; personal fees from Boehringer Ingelheim; personal fees from InFlarX; personal fees and other support from Roche; grants, personal fees and other support from Novartis; personal fees from Incyte; personal fees and other support from Regeneron; personal fees from 4SC; personal fees from Sanofi; personal fees from Neracare; personal fees from Pierre-Fabre; personal fees and other support from Merck-EMD; personal fees from Pfizer; personal fees and other support from Philiogen; personal fees from Array, personal fees and other support from MSD Sharp & Dohme, outside the submitted work. E.L. served as consultant and/or has received honoraria from Bristol-Myers Squibb, Merck Sharp & Dohme, Novartis, Pierre-Fabre, Sanofi, Sunpharma, Takeda and travel support from Bristol-Myers Squibb, Pierre- Fabre, Sunpharma and Novartis, outside the submitted work.A.S. L.Z. served as consultant and/or has received honoraria from Roche, Bristol-Myers Squibb, Merck Sharp & Dohme, Novartis, Pierre-Fabre, and Sanofi; and travel support from Merck Sharp & Dohme, Bristol-Myers Squibb, Amgen, Pierre-Fabre, and Novartis, outside the submitted work. All remaining authors have declared no conflicts of interest., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Introduction: There is an urgent need for new or repurposed therapeutics that protect against or significantly delay the clinical progression of neurodegenerative diseases, such as Huntington's disease (HD), Parkinson's disease and Alzheimer's disease. In particular, preclinical studies are needed for well tolerated and brain-penetrating small molecules capable of mitigating the proteotoxic mitochondrial processes that are hallmarks of these diseases. We identified a unique suicide inhibitor of mitochondrial proline dehydrogenase (Prodh), N-propargylglycine (N-PPG), which has anticancer and brain-enhancing mitohormesis properties, and we hypothesize that induction of mitohormesis by N-PPG protects against neurodegenerative diseases. We carried out a series of mouse studies designed to: i) compare brain and metabolic responses while on oral N-PPG treatment (50 mg/kg, 9-14 days) of B6CBA wildtype (WT) and short-lived transgenic R6/2 (HD) mice; and ii) evaluate potential brain and systemwide stress rebound responses in WT mice 2 months after cessation of extended mitohormesis induction by well-tolerated higher doses of N-PPG (100-200 mg/kg x 60 days). WT and HD mice showed comparable global evidence of N-PPG induced brain mitohormesis characterized by Prodh protein decay and increased mitochondrial expression of chaperone and Yme1l1 protease proteins. Interestingly, transcriptional analysis (RNAseq) showed partial normalization of HD whole brain transcriptomes toward those of WT mice. Comprehensive metabolomic profiles performed on control and N-PPG treated blood, brain, and kidney samples revealed expected N-PPG-induced tissue increases in proline levels in both WT and HD mice, accompanied by surprising parallel increases in hydroxyproline and sarcosine. Two months after cessation of the higher dose N-PPG stress treatments, WT mouse brains showed robust rebound increases in Prodh protein levels and mitochondrial transcriptome responses, as well as altered profiles of blood amino acid-related metabolites. Our HD and WT mouse preclinical findings point to the brain penetrating and mitohormesis-inducing potential of the drug candidate, N-PPG, and provide new rationale and application insights supporting its further preclinical testing in various models of neurodegenerative diseases characterized by loss of mitochondrial proteostasis., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Author(s). Published by Elsevier B.V. All rights reserved.)

Cellular senescence, a hallmark of aging, results in a senescence-associated secretory phenotype (SASP) with an increased production of proinflammatory cytokines, growth factors, and proteases. Evidence from nonhuman models demonstrates that SASP contributes to tissue dysfunction and pathological effects of aging. However, there are relatively few human studies on the relationship between SASP and aging-related health outcomes. Proteins from the SASP Atlas were measured in plasma using aptamer-based proteomics (SomaLogic). Regression models were used to identify SASP protein associations with aging-related traits representing multiple aspects of physiology in 1 201 participants from 2 human cohort studies (BLSA/GESTALT and InCHIANTI). Traits examined were fasting glucose, C-reactive protein, interleukin-6, alkaline phosphatase, blood urea nitrogen, albumin, red blood cell distribution width, waist circumference, systolic and diastolic blood pressure, gait speed, and grip strength. Study results were combined with a fixed-effect inverse-variance weighted meta-analysis. In the meta-analysis, 28 of 77 SASP proteins were significantly associated with age. Of the 28 age-associated SASP proteins, 18 were significantly associated with 1 or more clinical traits, and 7 SASP proteins were significantly associated with 3 or more traits. Growth/differentiation factor 15, Insulin-like growth factor-binding protein 2, and Cystatin-C showed significant associations with inflammatory markers and measures of physical function (grip strength or gait speed). These results support the relevance of SASP proteins to human aging, identify specific traits that are potentially affected by SASP, and prioritize specific SASP proteins for their utility as biomarkers of human aging., (© The Author(s) 2023. Published by Oxford University Press on behalf of The Gerontological Society of America.)

The post-translational modification lysine succinylation is implicated in the regulation of various metabolic pathways. However, its biological relevance remains uncertain due to methodological difficulties in determining high-impact succinylation sites. Here, using stable isotope labelling and data-independent acquisition mass spectrometry, we quantified lysine succinylation stoichiometries in mouse livers. Despite the low overall stoichiometry of lysine succinylation, several high-stoichiometry sites were identified, especially upon deletion of the desuccinylase SIRT5. In particular, multiple high-stoichiometry lysine sites identified in argininosuccinate synthase (ASS1), a key enzyme in the urea cycle, are regulated by SIRT5. Mutation of the high-stoichiometry lysine in ASS1 to succinyl-mimetic glutamic acid significantly decreased its enzymatic activity. Metabolomics profiling confirms that SIRT5 deficiency decreases urea cycle activity in liver. Importantly, SIRT5 deficiency compromises ammonia tolerance, which can be reversed by the overexpression of wild-type, but not succinyl-mimetic, ASS1. Therefore, lysine succinylation is functionally important in ammonia metabolism., (© 2024. The Author(s), under exclusive licence to Springer Nature Limited.)

Acute kidney injury (AKI) manifests as a major health concern, particularly for the elderly. Understanding AKI-related proteome changes is critical for prevention and development of novel therapeutics to recover kidney function and to mitigate the susceptibility for recurrent AKI or development of chronic kidney disease. In this study, mouse kidneys were subjected to ischemia-reperfusion injury, and the contralateral kidneys remained uninjured to enable comparison and assess injury-induced changes in the kidney proteome. A ZenoTOF 7600 mass spectrometer was optimized for data-independent acquisition (DIA) to achieve comprehensive protein identification and quantification. Short microflow gradients and the generation of a deep kidney-specific spectral library allowed for high-throughput, comprehensive protein quantification. Upon AKI, the kidney proteome was completely remodeled, and over half of the 3945 quantified protein groups changed significantly. Downregulated proteins in the injured kidney were involved in energy production, including numerous peroxisomal matrix proteins that function in fatty acid oxidation, such as ACOX1, CAT, EHHADH, ACOT4, ACOT8, and Scp2. Injured kidneys exhibited severely damaged tissues and injury markers. The comprehensive and sensitive kidney-specific DIA-MS assays feature high-throughput analytical capabilities to achieve deep coverage of the kidney proteome, and will serve as useful tools for developing novel therapeutics to remediate kidney function., (© 2023 The Authors. PROTEOMICS published by Wiley-VCH GmbH.)

Poor bone quality is a major factor in skeletal fragility in elderly individuals. The molecular mechanisms that establish and maintain bone quality, independent of bone mass, are unknown but are thought to be primarily determined by osteocytes. We hypothesize that the age-related decline in bone quality results from the suppression of osteocyte perilacunar/canalicular remodeling (PLR), which maintains bone material properties. We examined bones from young and aged mice with osteocyte-intrinsic repression of TGFβ signaling (TβRII ocy-/- ) that suppresses PLR. The control aged bone displayed decreased TGFβ signaling and PLR, but aging did not worsen the existing PLR suppression in male TβRII ocy-/- bone. This relationship impacted the behavior of collagen material at the nanoscale and tissue scale in macromechanical tests. The effects of age on bone mass, density, and mineral material behavior were independent of osteocytic TGFβ. We determined that the decline in bone quality with age arises from the loss of osteocyte function and the loss of TGFβ-dependent maintenance of collagen integrity., (© 2024. The Author(s).)

Synaptic plasticity is obstructed by pathogenic tau in the brain, representing a key mechanism that underlies memory loss in Alzheimer's disease (AD) and related tauopathies. Here, we found that reduced levels of the memory-associated protein KIdney/BRAin (KIBRA) in the brain and increased KIBRA protein levels in cerebrospinal fluid are associated with cognitive impairment and pathological tau levels in disease. We next defined a mechanism for plasticity repair in vulnerable neurons using the C-terminus of the KIBRA protein (CT-KIBRA). We showed that CT-KIBRA restored plasticity and memory in transgenic mice expressing pathogenic human tau; however, CT-KIBRA did not alter tau levels or prevent tau-induced synapse loss. Instead, we found that CT-KIBRA stabilized the protein kinase Mζ (PKMζ) to maintain synaptic plasticity and memory despite tau-mediated pathogenesis. Thus, our results distinguished KIBRA both as a biomarker of synapse dysfunction and as the foundation for a synapse repair mechanism to reverse cognitive impairment in tauopathy.