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Background: Natural killer (NK) cells are key effector lymphoid cells involved in both innate and adaptive immunity and are capable of clearing abnormally aggregated α-synuclein (αSyn). In preclinical Parkinson’s disease (PD) models, NK cell depletion worsens motor deficits and increases insoluble αSyn accumulation, suggesting a neuroprotective role. However, the therapeutic potential of NK cell transfer in modulating αSyn pathology and neurodegeneration remains unexplored. Methods: To assess the efficacy of NK cell therapy, we administered biweekly systemic injections of untouched NK cells isolated from B6C3H donor mice into 2-month-old presymptomatic homozygous M83 transgenic mice injected with human αSyn preformed fibrils. Neurological function was assessed via clasping behavior and clinical scoring. αSyn pathology and dopaminergic neurodegeneration were evaluated via immunohistochemistry. CyTOF-based immune profiling and multiplex ELISA were performed to characterize central and peripheral immune responses. Results: Adoptive NK cell transfers improved motor function and reduced αSyn pathology in a region- and dose-dependent manner, with significant reductions in phosphorylated-αSyn inclusions and tyrosine hydroxylase-positive neuronal loss in the substantia nigra. NK cell transfer modulated the CNS immune landscape by reducing CD11b+CD45high and MHCII+ activated microglial, CD4⁺ T cells, and neutrophil infiltration, while promoting CD19+ B and CD8+ T cells. Similar immunomodulatory effects were observed in the periphery, including restoration of follicular B cells and reduced neutrophil frequencies. Mechanistically, αSyn exposure downregulated activating NK ligands and upregulated inhibitory receptor ligand mQa1b, along with p21 induction in microglia, suggesting a senescence-associated, immune-evasive phenotype that may contribute to reduced therapeutic efficacy at later disease stages. Conclusions: Our study provides direct evidence of NK cells exerting neuroprotective and immunomodulatory effects in a preclinical model of synucleinopathy. These findings support NK cell transfer as a novel therapeutic strategy for PD and related neurodegenerative disorders.

Systemic sclerosis (SSc) is an autoimmune disease marked by fibrosis and extensive autoantibody production. Although B-cell depletion with rituximab (RTX) has shown clinical benefit, predictive biomarkers of response remain elusive. Here, we apply proteome-wide autoantibody screening using wet protein arrays covering 13,455 human antigens in serum samples from participants of the randomized trial of RTX. We identify a significant elevation in the total autoantibody levels in SSc compared to healthy controls, with greater reductions post-treatment observed in RTX high responders than in low responders. A stepwise selection highlights 88 clinically relevant autoantibodies, including those targeting G protein-coupled receptors. Among them, anti-C-C motif chemokine receptor 8 (CCR8) autoantibodies are functionally validated by cell-based assays using CCR8-overexpressing HEK293 cells. Furthermore, in a bleomycin-induced mouse model, anti-CCR8 antibody administration exacerbates dermal fibrosis and modifies immune cell infiltration. Although external validation with multiple comparison adjustment is further required, these findings reveal an autoantibody signature associated with therapeutic response and pathogenic potential in SSc, providing a foundation for precision immunotherapy and mechanistic insights into disease progression. B-cell depletion benefits systemic sclerosis, but predictive biomarkers remain limited. The authors here map autoantibody profiles using proteome-wide screening, identify C-C motif chemokine receptor 8-targeting autoantibodies with functional impact, suggesting novel pathophysiology and precision therapy targets.

Recessive dystrophic epidermolysis bullosa (RDEB) is a severe inherited skin disorder caused by mutations in COL7A1. Patient-derived induced pluripotent stem cells (iPSCs) enable the personalized study of RDEB pathogenesis and potential therapies. However, current skin cell differentiation protocols via 2D culture perform suboptimally when applied to engineered 3D skin constructs (ESC). Here, we present an approach to source fibroblasts (iFBs) and keratinocytes (iKCs) from iPSC-derived skin organoids using an optimized differentiation protocol, and utilize them to engineer ESCs modeling wild-type and RDEB phenotypes. The resulting iPSC-derived skin cells display marker expression consistent with primary counterparts and produce ESCs exhibiting significant extracellular matrix remodeling, protein deposition, and epidermal differentiation. RDEB constructs recapitulated hallmark disease features, including absence of collagen VII and reduced iFB proliferation. This work establishes a robust and scalable strategy for generating physiologically-relevant, iPSC-derived skin constructs, offering a powerful model for studying RDEB mechanisms and advancing personalized regenerative medicine.

Background: Recurrent/metastatic head and neck squamous cell carcinoma ((R/M) HNSCC) represents one of the most aggressive and immunosuppressive cancers. Despite the introduction of immune checkpoint inhibitors (ICIs), only a limited number of patients obtain long-term benefits. In (R/M) HNSCC patients, the antitumor immune response is defective, conferring resistance and promoting tumor progression. Therefore, the identification of novel biomarkers for superior clinical outcomes and easily accessible in standard clinical settings is still an unmet clinical need. Methods: Blood liquid biopsies obtained from (R/M) HNSCC patients undergoing pembrolizumab therapy (monotherapy or in combination with chemotherapy) were analyzed by flow cytometry to evaluate the levels of circulating immunosuppressive regulatory T cells (Tregs) and myeloid derived suppressor cells (MDSCs), at baseline and during therapy. Correlations between these immunosuppressive immune cell subsets and clinical parameters (clinical response rate, progression-free survival (PFS), overall survival (OS) and performance status (PS)) were performed. Results: Univariate analysis showed that before therapy, higher circulating levels of both CD137⁺Tregs and LOX-1⁺PMN-MDSCs, identified patients with significantly worse survival. Furthermore, CD137⁺Tregs resulted also positively correlated with worse PS, while high levels of LOX-1⁺PMN-MDSCs negatively affected response to pembrolizumab, with a significant increase in non-responsive patients during therapy. Interestingly, both CD137⁺Tregs as well as LOX-1⁺PMN-MDSCs exerted a higher immunosuppression on T cell proliferation than CD137−Tregs and LOX-1⁻PMN-MDSCs, respectively. Multivariate analysis revealed that the circulating LOX-1⁺PMN-MDSC subset resulted as an independent prognostic factor for survival by multivariate analysis, as confirmed in an independent validation cohort. Conclusions: The levels of blood circulating LOX-1⁺PMN-MDSCs may be proposed as non-invasive biomarkers to predict clinical outcomes of (R/M) HNSCC patients developing resistance to immunotherapy, improving patient selection and suggesting novel personalized therapies.

Endogenous long double-stranded RNAs (dsRNAs), which are not edited by the RNA editing enzyme ADAR1, may activate the antiviral dsRNA receptor MDA5 to trigger interferon-mediated immune responses. Among the large number of endogenous long dsRNAs, the key substrates that activate MDA5—termed as immunogenic dsRNAs—remain largely unidentified. Here we reveal that human immunogenic dsRNAs constitute a surprisingly small fraction of all cellular dsRNAs. We found that these immunogenic dsRNAs were highly enriched in mRNAs and depleted of introns, consistent with their role as cytosolic MDA5 substrates. We validated the MDA5-dependent immunogenicity of these dsRNAs, which was dampened following ADAR1-mediated RNA editing. Notably, immunogenic dsRNAs were enriched at genetic susceptibility loci associated with common inflammatory diseases, implying their functional importance. We anticipate that a focused analysis of immunogenic dsRNAs will enhance our understanding and treatment of cancer and inflammatory diseases, where the roles of dsRNA editing and sensing are increasingly recognized. The authors show that only a small subset of cytosolic double-stranded RNAs (dsRNAs) requires ADAR1-mediated RNA editing to evade an MDA5-dependent immune response. These immunogenic dsRNAs are enriched in mRNAs and overlap with GWAS signals for common inflammatory diseases.

Autophagy-based targeted degradation offers a powerful complement to proteasomal degradation leveraging the capacity and versatility of lysosomes to degrade complex cargo. However, it remains unclear which components of the autophagy-lysosomal pathway are most effective for targeted degradation. Here, we describe two orthogonal induced-proximity strategies to identify autophagy effectors capable of degrading organelles and soluble targets. Recruitment of autophagy cargo receptors, ATG8-like proteins, or the kinases ULK1 and TBK1 is sufficient to trigger mitophagy, while only autophagy cargo receptors capable of self-oligomerization degrade soluble cytosolic proteins. We further report a single-domain antibody against p62 and its use as a heterobifunctional degrader to clear mitochondria. Fusing the p62 single-domain antibody to PINK1 enables selective targeting of damaged mitochondria. Our study highlights the importance of avidity for targeted autophagy and suggests that autophagy cargo receptors are attractive entry points for the development of heterobifunctional degraders for organelles or protein aggregates. Using proximity-based screening, protein engineering, and structural analysis, this study describes the development of a p62-based biodegrader for the clearance of organelles and aggregated proteins by autophagy-targeted degradation.

Purpose: Noninfectious uveitis is a sight-threatening autoimmune eye disease lacking effective targeted therapies. Dipyridamole (DIP), a phosphodiesterase (PDE) inhibitor, has demonstrated anti-inflammatory properties in inflammatory diseases. However, its application in uveitis remains unexplored. Methods: We used single-cell RNA sequencing (scRNA-seq) data from experimental autoimmune uveitis (EAU) mice and uveitis patients to assess the potential association of PDE gene expression with disease development. Subsequently, EAU mice received oral DIP (300 mg/kg/day), starting at different time points (preventative, early-therapeutic, or late-therapeutic), and treatment efficacy was assessed. To explore immune components and signaling changes, we profiled cervical draining lymph nodes (CDLNs) from control, EAU, and DIP-treated mice by scRNA-seq and validated key findings with additional experiments. Mechanistically, pharmacologic interventions (an adenylyl cyclase inhibitor and the STAT3 agonist) were used in vitro. Results: Expression of several PDE genes correlated with uveitis severity in both human and mouse. Preventative DIP treatment most effectively reduced fundus inflammation in EAU and modulated the Teff/Treg ratio in the CDLNs and spleens. In vitro, DIP suppressed CD4+ T cell proliferation, and inhibited pathogenic Teff. scRNA-seq analysis revealed that DIP partially reversed EAU-induced transcriptional alterations, with notable changes in immune cell composition and pathway activity. Mechanistically, DIP downregulated STAT3 activity and PIM1 expression in Th17 cells via cAMP, suggesting the involvement of the cAMP-STAT3-PIM1 axis in modulating immune homeostasis. Conclusions: DIP ameliorated intraocular inflammation, modulated Th17/Treg balance, and reduced Th17 pathogenicity in EAU, potentially via cAMP-STAT3-PIM1 signaling. These findings highlight DIP as a promising therapeutic candidate for autoimmune uveitis.

Cutaneous tuberculosis (CTB) is an infectious disease highly associated with extracellular matrix remodeling and granuloma-driven fibrosis. Fibroblasts play crucial roles in this fibrotic process, but their specific roles in Mycobacterium tuberculosis (Mtb) skin infections remain unclear due to the lack of proper in vitro models. Here, we demonstrate that skin organoids (SKOs) derived from human induced pluripotent stem cells can model CTB infected by Mtb. Single-cell RNA analyses reveal an increase in fibroblasts, upregulation of genes involved in collagen synthesis, and enhanced collagen degradation induced by MMP2 and MMP14 in Mtb-infected SKOs. This is accompanied by the destruction of nerve cells and adipocytes. Importantly, the onset of fibrosis in Mtb-infected SKOs is dependent on the activation of the PI3K-AKT signaling pathway and transcription factor AP1 in fibroblasts. Pharmacological inhibition of PI3K-AKT and AP1 alleviates fibrosis and collagen deposition. Our findings have uncovered distinct alterations in cell populations during Mtb-induced skin fibrosis, highlighting the crucial roles of PI3K-AKT and AP1. The study demonstrates the utility of SKOs for investigating CTB pathogenesis and evaluating potential antifibrotic treatments. Cutaneous tuberculosis is an infectious disease associated with extracellular matrix remodeling and granuloma-driven fibrosis. Here, the authors present an in vitro model of this disease using skin organoids infected with Mycobacterium tuberculosis, and describe infection-induced alterations in specific pathways and cell populations.

Acute myeloid leukemia (AML) is primarily driven by leukemic stem cells (LSCs), the main cause of relapse and therapy resistance. Here, we discover that LSCs are predominantly small and mechanically soft. These mechanical properties enable their selective isolation using microfluidic chips. Single-cell RNA-sequencing of primary human AML bone marrow identifies enrichment of LSCs within the FSClow ALDH1A1+ subpopulation, which exhibits long-term stemness in functional assays. Notably, inhibiting ALDH1A1 in these cells promotes F-actin polymerization and increases cellular stiffness, reducing their stemness while enhancing their susceptibility to natural killer (NK) cell-mediated cytotoxicity. In AML patient-derived xenograft models, the combination of ALDH1A1 inhibition with NK cell therapy markedly suppresses leukemia progression. These findings suggest that targeting the mechanical properties of LSC offers a promising strategy to overcome AML treatment resistance, providing insights into stem cell mechanobiology and paving the way for combining targeted therapies with immunotherapy to improve clinical outcomes. Leukemic stem cells (LSCs) drive relapse and therapy resistance in acute myeloid leukemia (AML). Here, the authors show that increasing the stiffness of LSCs reduces their stemness and enhances their susceptibility to natural killer cell-mediated immunotherapy in AML.

Genetic variants in the X‐chromosomal gene coding for the calcium−/calmodulin‐dependent serine protein kinase (CASK) are associated with a neurodevelopmental disorder. CASK is a member of the membrane‐associated guanylate kinase (MAGUK) family of proteins. It acts as a scaffold at presynaptic sites, as a regulator of the transport of glutamate receptors, and as a transcriptional regulator. The PDZ domain of CASK has been reported to bind to presynaptic cell adhesion molecules such as Neurexin1‐3, CNTNAP2, SynCAM and SALM1. Structural analyses of related MAGUKs indicate that the canonical SH3 and GK domains combine with the PDZ domain to form the so‐called PSG supramodule. Conserved aromatic residues (Y723 and W914) flanking the GK domain contribute to the formation of a dimeric structure of two PSG modules, which is required for high‐affinity binding to the type 2 PDZ ligand motif of, for example, Neurexin. Here we identify previously uncharacterized patient variants in the SH3 domain of CASK (I672V; P673L), which alter the intermolecular binding pocket for Y723. Both variants interfere with the binding of Neurexin‐1β, in a manner similar to the previously reported Y723C variant. Intriguingly, binding to the type 1 PDZ ligand of the cell adhesion molecule SALM1 is not altered. Using a set of highly selective patient variants, we show that the binding of SALM1 to CASK is actually not mediated by the CASK PDZ domain or the PSG supramodule, but depends on other type 1 PDZ domain‐containing proteins such as SAP97 and Veli, which associate with CASK through its L27 domains. Our data underline the relevance of an intact PSG tandem of CASK for human health.

Background: Acute Lung Injury (ALI) and its most severe form, Acute Respiratory Distress Syndrome (ARDS), are critical pulmonary conditions characterized by life-threatening acute hypoxic respiratory failure, affecting over three million individuals globally each year. ALI involves alveolar inflammation and disruption of the alveolar-capillary barrier, primarily driven by neutrophil infiltration and the release of inflammatory mediators. In our previous study using a lipopolysaccharide (LPS)-induced mouse model of ALI, we demonstrated that C6, a peptide inhibitor of voltage-gated proton channels (Hv1), ameliorates lung injury, identifying Hv1 as a potential therapeutic target. However, (i) whether the anti-inflammatory effects of C6 are translatable to a clinically relevant live bacterial infection model, and (ii) the molecular mechanisms underlying these anti-inflammatory effects, remain unknown, and are a crucial next step towards targeted rational drug development. Methods: To induce ALI, we used an intratracheal Pseudomonas aeruginosa infection model, a gram-negative bacterium relevant in ventilated and immunocompromised patients. A separate group of infected mice also received intravenous treatment with C6 (4 mg/kg). Lung injury severity was evaluated using histopathological analysis. Bronchoalveolar lavage (BAL) fluid was collected to quantify neutrophil infiltration and proinflammatory cytokines concentrations. In addition, reactive oxygen species (ROS) production and intracellular calcium levels in BAL neutrophils were measured. RNA sequencing of BAL neutrophils was conducted to assess C6-induced transcriptional changes. Key findings were validated in vitro using human neutrophils. Results: C6 mitigates P. aeruginosa-induced ALI in mice by reducing neutrophil infiltration into the alveolar space by ~ 86%, improving lung injury scores, decreasing BAL fluid proinflammatory cytokine levels, and suppressing neutrophil ROS production and intracellular calcium levels. RNA sequencing of BAL neutrophils revealed 51 downregulated genes, including key regulators of neutrophil migration, cytokine release, and ROS production; only three genes were upregulated and they also have roles in neutrophil immune defense. In human neutrophils, C6 similarly inhibited chemotaxis and reduced ROS and cytokine release, and calcium influx. Conclusions: Targeting Hv1 with C6 effectively protects against P. aeruginosa-induced ALI by limiting neutrophil recruitment and activation. These findings establish C6 as a promising therapeutic candidate against infectious ALI and provide important mechanistic insights into its immunomodulatory effects on neutrophils.

How the neuroectoderm-derived eye field breaks symmetry to specify iris muscle is not well understood. Recent studies have begun to transcriptionally characterize mouse iris muscle; however, little is known about the transcriptional foundation of human iris development. Human pluripotent stem cells (hPSCs) enable the study of iris muscle specification. Here we compare iris smooth muscle from native adult iris tissues to evaluate successful specification of iris muscle from hPSC lines. We utilize a previously published eye-like organoid protocol that specified cells of the eye field to also generate iris muscle. We describe a population transcriptionally similar to native iris and describe an iris muscle gene signature. Human iris muscle not only contains pigment, but also expresses pigment synthesis genes and is responsive to acetylcholine. Integration of single-cell RNA-seq datasets confirm the similarity between the iris muscle to the adult iris, establishing the usefulness of the model in studying neuroectoderm-derived iris muscle specification, and related diseases. Single-cell RNA sequencing reveals that iris muscle, derived from neuroectoderm, can form in stem cell–derived eye organoids – enabling the modelling of iris muscle pathologies like aniridia and proliferative vitreoretinopathy.