Biology subjects

Palmfeldt, J.

Publications and source records attributed to Palmfeldt, J..

11 recordsLinked to original sources

bioRxiv2026

Thymic Treg-derived T follicular regulatory cells prevent catastrophic humoral autoimmunity in response to TLR7-driven inflammation

T follicular regulatory cells (TFR) are a follicle-resident subset of regulatory T cells (TREG) that limit germinal center (GC) responses and enforce humoral tolerance. Although TFR are known to focus antibody responses to foreign antigens, how GC-specific regulation is maintained during inflammation remains unclear. Here, TLR7-driven inflammation unmasked a critical, non-redundant role for TFR in preserving immune tolerance. Selective loss of TFR caused severe autoimmunity and increased mortality, driven by inflammation-induced expansion of autoreactive B and T cell clones and epitope spreading. Autoreactivity resolved upon cessation of inflammation in TFR-sucicient mice but persisted in their absence. Mechanistically, TFR limited the establishment and expansion of spontaneous GCs in response to inflammation, and responding TFR displayed transcriptional, phenotypic, and clonal features of thymic TREG. This suggests that whereas TFH upregulate FoxP3 to shut down end-stage GCs, it is thymic TREG-derived TFR that safeguard GC integrity under inflammatory stress to prevent lethal autoimmunity.

immunology↗

bioRxiv2026

The muscle atrophic phenotype of MuSK myasthenia gravis: Insights from a preclinical rat model

Myasthenia gravis with muscle-specific kinase antibodies (MuSK-MG) is an autoimmune disorder marked by neuromuscular junction (NMJ) disruption and selective muscle atrophy, yet its intrinsic myocellular mechanisms remain unclear. Using a rat model generated by active immunization with the N-terminal MuSK60 peptide, we characterized muscle pathology, NMJ morphology, and whole-muscle proteome remodeling across anatomically distinct skeletal muscles. Anti-MuSK rats developed seropositivity, body-mass loss, fragmented and denervated NMJs, and pronounced atrophy restricted to slow-twitch/type I fibers, particularly in the soleus muscle. Quantitative proteomics identified extensive muscle-specific alterations, most prominent in soleus, with fewer in diaphragm and sternohyoideus. Gene set enrichment analysis revealed coordinated downregulation of mitochondrial, ribosomal, and myosin-complex proteins in soleus, partial mitochondrial involvement in diaphragm, and compensatory upregulation of translational and proteasomal pathways in diaphragm. Correlation analysis linked soleus mass loss to elevated abundance of ubiquitin-proteasome and calcium-handling proteins, implicating proteolytic and bioenergetic stress mechanisms. The consistent upregulation of NCAM1 and MUSTN1 suggests generalized myocellular responses to MuSK dysfunction. Together, these data demonstrate that MuSK autoimmunity elicits fiber-type-selective atrophy and profound proteome remodeling beyond NMJ impairment, highlighting disrupted mitochondrial and translational homeostasis as central features of the MuSK-MG muscle phenotype.

molecular biology↗

bioRxiv2026

Differential Maillard Sensitivity Of Exoproteins Favors Keratin Recovery During Sludge Biopolymer Extraction

Proteins are an abundant extracellular polymeric substance (EPS) of activated sludge from wastewater. Hot alkalinization is implemented industrially to recover the EPS from sludge. We sought to assess the feasibility of protein recovery from alkali EPS. We detected a low abundance of bacterial proteins in the EPS. Human keratin was highly abundant and could also be recovered. Keratin was observed as a dominant and integral component of the activated sludge flocs, and it was thus not an extraction artifact. Alkali extraction promoted Maillard reaction between proteins and sugars and removed recoverable peptide signatures. Subsequent chemical modification, along with denaturation, impaired protein binding to ion exchange resins, making bacterial proteins inaccessible to isolation. Keratin has high resistance to Maillard reaction under extraction conditions and thus persists in the EPS. While Maillard modifies bacterial proteins, the resultant product, and possibly even keratin itself, are valuable recoverable byproducts from activated sludge. SynopsisThe different sensitivities of proteins to Maillard reaction determines which proteins dominate alkaline extracellular polymeric substance (EPS) extract from activated sludge, with keratin dominating in alkaline EPS and an integral activated sludge component.

biochemistry↗

bioRxiv2025

Transglutaminase 2 predicts parasitic worm-mediated protection against hepatic steatosis in obese mice

Parasitic worm infection can mitigate high fat diet-induced chronic inflammation in obese mice by reducing hepatic fat accumulation and improving insulin sensitivity. However, the molecular alterations during infection-mediated regulation of hepatic steatotic events in obesity remain poorly understood. Here, we integrated proteomic and metabolomic analyses of infected obese mice, a functional deworming and interleukin-4c (IL-4c) treated animal model, and an obese patient cohort before and after bariatric surgery to uncover molecular targets/pathways indicative of the regulation of hepatic steatosis by gut Heligmosomoides polygyrus bakeri (H. p. bakeri) helminth infection. Proteomic analysis identified alterations in several molecules related to metabolism and showed elevated levels of transglutaminase 2 (TGM2) proportionate with an infection-regulated lipid load in diet-induced obese (DIO) mice. The role of TGM2 as a reliable predictor of hepatic steatosis was validated using deworming experiments which revealed a decrease in the liver tissue levels of Tgm2 following removal of H. p. bakeri. Further validation showing increase in Tgm2 levels in IL-4c treated mice confirmed its relevance as a general response indicator of type 2 immune response induced by helminth infection. Assessment of circulating TGM2 levels in matched obese patients before and after bariatric surgery revealed no change, indicating that differential expression of TGM2 is a unique functional response to regulation of hepatic steatosis by H. p. bakeri infection. Together, our data show that TGM2 is a unique predictive marker of improvement in hepatic lipid profile and provides additional evidence that parasitic worm infection protects against hepatic steatosis in DIO mice. These findings pave the way for novel therapeutic opportunities to resolve hepatic steatosis and prevent its progression to severe forms of metabolic dysfunction-associated steatotic liver disease, based on TGM2 coupled with mimetics of H. p. bakeri-derived products. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=138 SRC="FIGDIR/small/689654v1_ufig1.gif" ALT="Figure 1"> View larger version (36K): org.highwire.dtl.DTLVardef@1cae718org.highwire.dtl.DTLVardef@9ec0aorg.highwire.dtl.DTLVardef@1679b1corg.highwire.dtl.DTLVardef@f86bc9_HPS_FORMAT_FIGEXP M_FIG C_FIG

molecular biology↗

bioRxiv2025

The SorCS2-derived macrocycle TT-P34 drives neuroprotection in animal models of neurodegeneration

Mitochondria are critical for sustaining the high energy demands of neuronal activity and their dysregulation is a hallmark of neurodegeneration. Targeting pathways of neurotrophic signaling is a well-established therapeutic strategy to enhance mitochondrial function and mitigate neurodegeneration. The VPS10p domain receptor, SorCS2, has recently emerged as a receptor with neurotrophic signaling capabilities. Here, we design and develop novel SorCS2-derived macrocyclic peptides mimicking receptor activation in vivo. We show that SorCS2-peptides enhance both neurotrophic support and boost metabolism by activating CREB and AMPK in a CAMKK2-dependent manner. This leads to upregulation of the key transcription factors PGC1 and TFEB and consequentially mitochondrial biogenesis. Furthermore, we show that the lipidated SorCS2 macrocycle, TT-P34, rescues motor behavioral deficits and preserves synaptic and mitochondrial signatures in the zQ175 mouse model of Huntingtons Disease. In addition, treating a MPTP-induced mouse model of Parkinsons Disease leads to amelioration of behavioral deficits and reduction of dopaminergic loss. Finally, we demonstrate that TT-P34 crosses the blood-brain barrier in non-human primates, and estimate human therapeutic dosing by pharmacodynamic modelling. Together, our findings support the use of TT-P34 as a novel disease-modifying therapy targeting SorCS2-receptor signaling to prevent neurodegeneration.

neuroscience↗

bioRxiv2025

Familial Alzheimer disease mutation identifies novel role of SORLA in release of neurotrophic exosomes

Sortilin-related receptor with A-type repeats (SORLA) is an intracellular sorting receptor that directs target proteins between endocytic and secretory compartments of cells. Mutations in SORL1, encoding SORLA, are common in individuals suffering from Alzheimer disease (AD) of unknown etiology. Conceptually, characterization of inheritable SORL1 variants associated with AD can provide important new information about functions of this receptor relevant for aging brain health. Here, we focused on elucidation of the AD-associated variant SORLA N1358S, carrying a mutation in the main ligand binding domain of the receptor. Using unbiased quantitative proteome screens, we identified major alterations in the mutant receptor interactome linked to biogenesis and secretion of exosomes. Using advanced biophysical, cell biological, as well as functional studies in stem cell-derived human cell models we corroborated impaired release and loss of neurotrophic action of exosomes from neurons and microglia expressing SORLAN1358S. An impaired neurotrophic potential was attributed to an altered exosomal content of RNA binding proteins and associated microRNAs, known to control neuronal growth and maturation. Our studies identified a so far unknown function for SORLA in controlling the quantity and trophic quality of extracellular vesicles secreted by cells, and they argue for impaired cellular cross talk through exosomes as a pathological trail contributing to the risk of AD seen with carriers of SORL1 variants.

neuroscience↗

bioRxiv2024

Restoring oxidative phosphorylation enhances osteogenesis in mitochondrial DNA translation defective human bone marrow stromal cells

Bone formation is critical to maintain bone integrity. Here, we studied the importance of intact energy metabolism for bone formation in humans. The skeletal impact of impaired oxidative phosphorylation (OXPHOS) was investigated in adult individuals with genetically defective mitochondrial DNA translation (m.3243A>G). Although impaired mitochondrial ATP production in m.3243A>G human bone marrow stromal cells (hBMSC) was compensated by increased glycolytic ATP production (unchanged net ATP production), both in vitro osteoblast differentiation and in vivo ectopic bone formation were decreased. The impaired OXPHOS was associated with mitochondrial stress and disruption of the pro-osteogenic transcriptional program characteristic of hBMSC. Supporting OXPHOS pharmacologically in hBMSC restored mitochondrial ATP production, their transcriptional program and metabolism, leading to upregulation of osteogenic genes and restoration of bone formation capacity. These findings demonstrate a mitochondrial regulation mechanism of the osteogenic capacity of hBMSCs and identify OXPHOS as a potential target for increasing bone formation. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=141 SRC="FIGDIR/small/629993v1_ufig1.gif" ALT="Figure 1"> View larger version (24K): org.highwire.dtl.DTLVardef@fca817org.highwire.dtl.DTLVardef@17fb2d3org.highwire.dtl.DTLVardef@b5667forg.highwire.dtl.DTLVardef@15c35db_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

bioRxiv2024

Carbonic anhydrase inhibitors prevent presymptomatic capillary flow disturbances in a model of cerebral amyloidosis

Structured abstractO_ST_ABSINTRODUCTIONC_ST_ABSDisturbances in microvascular flow dynamics are hypothesized to precede the symptomatic phase of Alzheimers disease (AD). However, evidence in presymptomatic AD remains elusive, underscoring the need for therapies targeting these early vascular changes. METHODSWe employed a multimodal approach, combining in vivo optical imaging, molecular techniques, and ex vivo MRI, to investigate early capillary dysfunction in Tg-SwDI mice without memory impairment. We also assessed the efficacy of carbonic anhydrase inhibitors (CAIs) in preventing capillary flow disturbances. RESULTSOur study revealed capillary flow disturbances associated with alterations in capillary morphology, adhesion molecule expression, and Amyloid-{beta} (A{beta}) load in 9-10-month-old Tg-SwDI mice without memory impairment. CAI treatment ameliorated these capillary flow disturbances, enhanced oxygen availability, and reduced A{beta} load. DISCUSSIONThese findings underscore the importance of capillary flow disturbances as early biomarkers in presymptomatic AD and highlight the potential of CAIs for preserving vascular integrity in the early stages of AD.

neuroscience↗

bioRxiv2024

HSP60 chaperone deficiency disrupts the mitochondrial matrix proteome and dysregulates cholesterol synthesis

Mitochondrial proteostasis is critical for cellular function and survival. HSP60 is a molecular chaperone that interacts with more than 260 mitochondrial matrix proteins to assist in their folding and few genetic variants of HSP60 are compatible with life. The few reported human patients with HSP60 variants show phenotypes of neurodevelopmental delay associated with brain hypomyelination. It is currently unknown how deficiency of the HSP60 links to hypomyelination. Here, we studied the onset and progression of HSP60 deficiency in: (1) a HSP60 mutation-inducible cell system, (2) skin fibroblasts from patients with disease-associated HSP60 variants, and (3) zebrafish HSP60 knockout larvae. Collectively, we show how HSP60 deficiency leads to pervasive dysfunctions: (1) downregulated mitochondrial matrix proteome, (2) transcriptional activation of cytosolic stress responses, (3) and lipid accumulation with dysregulated cholesterol biosynthesis. In zebrafish larvae HSP60 deficiency induced early developmental abnormalities. Our comprehensive data identifies HSP60 as a master regulator of mitochondrial proteostasis and suggests a pivotal effect of HSP60 dysfunction on myelination through dysregulation of cholesterol biosynthesis. HighlightsO_LIHSP60 deficiency disrupts mitochondrial matrix proteins activating stress responses C_LIO_LIDisrupted matrix proteome impairs catabolism causing acetyl-CoA shortage C_LIO_LIHSP60 deficiency dysregulates cytosolic cholesterol synthesis C_LIO_LIHsp60 deficiency causes developmental abnormalities in zebrafish larvae C_LIO_LIDysregulated cholesterol synthesis links HSP60 deficiency to hypomyelination C_LI Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=59 SRC="FIGDIR/small/578131v1_ufig1.gif" ALT="Figure 1"> View larger version (11K): org.highwire.dtl.DTLVardef@891066org.highwire.dtl.DTLVardef@93ae5borg.highwire.dtl.DTLVardef@19bded0org.highwire.dtl.DTLVardef@414428_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

bioRxiv2021

Energy metabolism adaptations and gene expression reprogramming in a cellular MAFLD model

Mitochondrial dysfunction plays a critical role in metabolic associated fatty liver disease (MAFLD). This study aims to characterize mitochondrial dysfunctions in a human MAFLD Huh7 cell model triggered by free fatty acid (FFA) (palmitate and oleate) overload for 24 hours. We investigate its impact on cellular energy metabolism and identify potential targets for MAFLD treatment. FFA-treated cells displayed an accumulation of lipid droplets and slightly decreased viability but no significant changes in mitochondrial superoxide levels. Bioenergetic analysis showed a shift to more respiration and less glycolytic fermentation. Comprehensive transcriptomics and proteomics analyses identified changes in the expression of genes prominently involved in fatty acid handling and metabolism. The expressions of seven genes were consistently and significantly (p < 0.05) altered (4 upregulated and 3 downregulated genes) in both proteomics and transcriptomics. The FFA-treated Huh7 cell model is an appropriate in vitro model to study fatty acid metabolism and suitable to investigate the role of mitochondria, glycolysis, and multiple metabolic pathways in MAFLD. Our comprehensive analyses form a basis for drug discovery and screening using this model.

cell biology↗

bioRxiv2018

The behavioral and neurobiological effects of reduced Brd1 expression in mice are sex-biased and implicate gender dependent dysregulation of nuclear receptor mediated signaling in mental disorders

The schizophrenia and bipolar disorder associated gene, BRD1, encodes a scaffold protein that in complex with epigenetic modifiers regulate gene sets enriched for psychiatric disorder risk. Preclinical evidence from male Brd1+/- mice has previously implicated BRD1 with phenotypes of translational relevance to schizophrenia. Here we describe the phenotype of female Brd1+/- mice and report attenuated dendritic architecture and monoaminergic dysregulation accompanied by sex-specific changes in affective behaviors. In accordance, global gene expression profiling reveals regional dysregulation of gene sets enriched with major depressive disorder and schizophrenia risk in female and male Brd1+/- mice, respectively. Independent of sex, however, differentially expressed genes cluster in common functional pathways associated with psychiatric disorders, including mitochondrial dysfunction and oxidative phosphorylation as well as G-protein coupled-, and nuclear receptor mediated signaling. Accordingly, we provide in vitro evidence that BRD1 modulates the transcriptional drive of a subset of nuclear receptors (e.g. the vitamin D and glucocorticoid receptors). Moreover, we demonstrate enrichment of psychiatric disorder risk in the target genes of nuclear receptors, sex-biased expression of several nuclear receptor genes in the adult brain of Brd1+/- mice, and that sex-biased genes in general are enriched with nuclear receptor genes particularly at the earliest developmental stage of the human brain. Overall, our data suggests that the spatio-temporal interaction between BRD1 and subsets of nuclear receptors in the brain is sex-biased and that hampered BRD1 mediated regulation of target genes governed by certain nuclear receptors may significantly contribute to sex differences in psychopathology.

neuroscience↗