JCI Insight

Pulmonary fibrosis (PF) involves excessive collagen accumulation, yet mechanisms shifting the balance of synthesis and degradation toward net deposition remain unclear. Myeloperoxidase (MPO) inversely correlates with survival in PF. Using the bleomycin model, we found MPO knockout (MPOko) mice were protected from fibrosis, and pharmacological MPO inhibition after peak inflammation (day 7) recapitulated this protection. MPO persisted in lung tissue 21 days post-injury despite neutrophil efflux, linking acute inflammation to sustained remodeling. Mechanistically, we identified that MPO inhibits Cathepsin K (CatK), a potent collagenolytic enzyme involved in fibrosis resolution. Notably, CatK gene expression (CTSK) is elevated in PF, suggesting post-translational inhibition of CatK. MPOko and inhibitor-treated mice exhibited elevated CatK activity after bleomycin; exogenous addition of pathophysiologic concentrations of MPO reduced CatK activity in mouse precision-cut lung slices and human fibroblasts. Biochemically, MPO reduced CatK activity to 33% of control. In two distinct cohorts of PF patients, we observed significantly increased MPO protein levels in platelet poor plasma and in lung tissue. In PF patients, 62% had MPO levels in platelet poor plasma exceeding healthy controls, while lung tissue from other PF patients showed significantly elevated MPO staining. Plasma levels were inversely correlated with decreased survival, FVC, and DLCO. These findings establish MPO as a post-translational inhibitor of CatK-mediated collagenolysis, revealing a mechanism linking acute inflammation to sustained fibrosis and suggest a patient subpopulation that may benefit from MPO-targeted therapy. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=54 SRC="FIGDIR/small/713467v1_ufig1.gif" ALT="Figure 1"> View larger version (17K): org.highwire.dtl.DTLVardef@d8fc5eorg.highwire.dtl.DTLVardef@1a088fcorg.highwire.dtl.DTLVardef@818b7dorg.highwire.dtl.DTLVardef@ecdca0_HPS_FORMAT_FIGEXP M_FIG C_FIG Myeloperoxidase persists in lung tissue after injury and inhibits cathepsin K activity, impairing collagen degradation and promoting extracellular matrix accumulation during pulmonary fibrosis.

Semaglutide has shown benefit in metabolic dysfunction-associated steatohepatitis (MASH), but real-world evidence across longitudinal liver phenotypes remains limited, particularly regarding how liver remodeling relates to weight loss and dose exposure. Using a de-identified federated electronic health record network spanning more than 29 million patients in the United States, including 489,785 semaglutide-treated adults, we analyzed 6,734 patients with baseline liver disease burden. We find that higher attained pre-landmark (0-2 years) semaglutide dose was associated with lower post-landmark (2-4 years) risk of steatohepatitis, alcoholic liver disease, and all-cause mortality, whereas greater pre-landmark weight loss was associated with lower post-landmark risk of steatohepatitis, steatotic liver disease, and hepatorenal syndrome, indicating distinct dose- and weight-linked patterns of long-term liver benefits. These associations were notable because semaglutide prescribing was generally lower during the post-landmark period, raising the possibility of durable benefit beyond peak exposure. Towards better understanding mechanistic bases for liver protection, we performed a complementary longitudinal study of 326 adults with paired noninvasive liver elastography measurements before and after treatment initiation. Median liver stiffness decreased from 4.85 [3.02 - 7.20] to 3.9 [2.6 - 5.8] kPa after semaglutide initiation (median change = -0.38 kPa; p<0.001), with 194 of 326 patients (59.5%) showing lower follow-up stiffness. A clinically meaningful reduction of at least 20% was observed in 133 of 326 patients (40.8%), and 69 of 326 (21.2%) shifted to a lower fibrosis stage by prespecified elastography thresholds. Larger improvements were also seen in patients with higher baseline stiffness (p<0.001); notably 80% of patients with cirrhosis-range baseline stiffness ([&ge;]12.5 kPa) achieved [&ge;]20% improvement versus 29.5% with minimal baseline disease (p <0.001). The proportion achieving at least 20% stiffness improvement was similar across weight-loss strata, including patients with no weight loss or weight gain and those with at least 10% weight loss (38.0% in each group), and liver stiffness change showed negligible correlation with changes in weight, BMI, HBA1c, alanine aminotransferase, or aspartate aminotransferase. To provide biological context, single cell RNA analyses demonstrated sparse overall hepatic GLP1R expression (0.0239%), with enrichment in non-parenchymal niches including cholangiocytes, intrahepatic cholangiocytes, liver sinusoidal endothelial cells, and hepatic stellate cells implicated in fibrogenesis and vascular remodeling. Together, this real-world evidence suggests diverse liver benefits for semaglutide beyond weight-loss with intricate dose response relationships.

The autosomal dominant p.Ala165Val mutation in LIM Domain Binding Protein 3 (LDB3) causes myofibrillar myopathy marked by Z-disc disruption, accumulation of filamin-C (FLNc) and chaperone proteins, and progressive muscle weakness. We previously showed that this mutation interferes with the LDB3-protein kinase C alpha (PKC)-FLNc mechanosensing axis and impairs chaperone-assisted selective autophagy (CASA), establishing a gain-of-function mechanism. In this study, we examined whether mutant allele-specific knockdown could reverse the disease or mitigate disease progression in-vivo. A single intramuscular-injection of an AAV9-delivered microRNA-based shRNA produced substantial knockdown of mutant Ldb3 transcripts and protein in Ldb3Ala165Val/+ knock-in mice treated either before or after the onset of pathology. Treatment after disease onset reduced filamin-C and CASA protein aggregates and improved muscle strength, whereas early intervention prevented development of molecular and histological features of myopathy. Phosphoproteomic profiling further showed broad remodeling of dysregulated phosphorylation networks, including restoration of PKC-responsive sites and normalization of altered sarcomeric and cytoskeletal signaling observed in Ldb3Ala165Val/+ mice. These findings identify disruption of the LDB3-PKC-FLNc mechanosensing pathway as a central disease driver and suggest that restoring this signaling axis may complement mutant allelespecific RNA interference (RNAi). Overall, our results support RNAi as a promising therapeutic strategy for dominant LDB3-related myofibrillar myopathy.

Red blood cell (RBC) alloimmunization is a clinically significant complication in transfused patients whose immunological determinants remain incompletely understood. Type I interferon (IFN-I) signaling drives RBC alloimmunization in murine models, and systemic lupus erythematosus (SLE) is characterized by constitutive IFN-I hyperactivation alongside elevated alloimmunization rates. We analyzed three publicly available SLE RNA-seq cohorts (GSE72509, GSE112087, GSE122459; whole blood and PBMC; total n = 150 SLE) in a pre-specified discovery-replication-validation design. A 14-gene IFN-I signature score was computed per sample; differential expression, gene set enrichment analysis, and Spearman correlation were performed independently per cohort. IFN-I scores were significantly elevated in SLE versus healthy controls in all three cohorts (p < 0.01 each). IFN-high SLE patients showed 665 differentially expressed genes, with enrichment of alloimmunization-associated and plasmablast differentiation gene sets confirmed by GSEA. The alloimmunization signature score correlated significantly with IFN-I score across all three independent cohorts ({rho} = +0.77, +0.51, +0.60; all FDR q < 0.05); Tfh differentiation showed no association in any cohort. To our knowledge, this represents the first human transcriptomic evidence that IFN-I pathway activity in SLE is coupled to alloimmunization-associated immune programs in vivo. These findings identify IFN-I score as a candidate biomarker of alloimmunization susceptibility in SLE and provide translational rationale for prospective studies incorporating transfusion outcome data.

Resolution of fibrosis following lung injury is distinguished from persistent/progressive parenchymal scarring through the timely clearance of aberrant cell types, removal of excess collagens, and regeneration of alveolar structure. The requisite signaling pathways, cellular cross-talk, and phenotypic shifts associated with, and required for, resolution of established lung fibrosis have not been well characterized. To address this critical knowledge gap, we performed longitudinal single-cell RNA sequencing of whole mouse lung digests obtained during spontaneously resolving fibrosis. We observed a putatively pro-fibrotic macrophage population emerge during peak fibrosis and undergo partial clearance during resolution. Our study also revealed conspicuous shifts in well-established pathways associated with tissue repair and fibrosis among immune, mesenchymal, and epithelial cells during spontaneous resolution. In addition to a decline in pro-fibrotic driver pathways, the putative anti-fibrotic pathways cAMP, HGF/MET, and TWEAK were enriched in several cell types during spontaneous resolution. CellChat analysis was used to predict the cellular senders and recipients of each pathway and characterize their longitudinal changes. Our characterization of the cellular and molecular dynamics in whole lungs during spontaneous fibrosis resolution provides a foundation for the identification of endogenous pathways that might be leveraged to treat pulmonary fibrosis.

Normal pressure hydrocephalus (NPH) is a potentially reversible neurological disorder characterized by urinary incontinence, gait impairment, and cognitive decline. However, postoperative improvement after shunt placement is variable, and reliable preoperative predictors are lacking, leaving patients exposed to uncertain surgical benefit and procedural risk. We therefore asked whether preoperative cerebrospinal fluid (CSF) metabolic profiles capture biological states associated with recovery potential. We analyzed ventricular CSF from patients undergoing shunt placement and identified metabolic patterns that differed between patients who improved postoperatively and those who did not. These signatures were detectable prior to intervention and were consistent across analytical approaches and patient cohorts. Multivariate models based on metabolite features were associated with postoperative improvement, with strongest performance observed for cognitive outcomes. Pathway-level analyses indicated coordinated alterations in processes related to redox balance, immune-metabolic signaling, and energy substrate utilization. These findings indicate that preoperative CSF metabolite profiles reflect biological states associated with recovery potential in NPH. The results further suggest that metabolic and immune-metabolic processes contribute to variability in surgical responsiveness and support the development of predictive biomarkers for patient stratification.

Rheumatoid arthritis is a prototypical autoimmune disease, characterised by prolonged systemic autoimmunity prior to organ-specific tissue inflammation. To achieve the contemporary goal of autoimmune disease prevention, a nuanced understanding of the transition from systemic autoimmunity to tissue-specific inflammation is critical. Here, we sought to identify immune signatures associated with the transition to subclinical joint inflammation detected by multi-joint ultrasound in anti-citrullinated protein antibodies (ACPA+)-positive individuals who imminently progress to RA. To achieve this, we performed single-cell transcriptomic and proteomic profiling on prospectively collected blood samples from high-risk ACPA+ imminent progressors, who were further stratified by the presence or absence of ultrasound (US)-detectable subclinical synovitis and compared them with ACPA+ non-progressors. We found type-1 interferon (IFN-I) activation in circulating CD14+ classical monocyte and GZMK+ CD8+ T cells preceding subclinical joint inflammation in ultrasound-negative (USneg) future progressors. In contrast, US-positive (USpos) future progressors exhibited a phenotypic shift in CD14+ classical monocytes towards IL1B+ expression and clonal expansion of GZMB+ cytotoxic CD8+ T cells at the onset of subclinical synovitis. Plasma proteomics also revealed a shift from Toll-like receptor-associated innate pathways in USneg future progressors toward effector and tissue-remodeling signatures in USpos future progressors. These findings suggest IFN-I-driven immune priming in specific immune subsets precedes the onset of subclinical joint inflammation, whereas tissue-directed inflammatory and cytotoxic programmes emerge at the onset of joint inflammation when clinical RA is imminent.

Intervertebral disc degeneration is associated with loss of nucleus pulposus (NP) cell phenotype and extracellular matrix, both processes linked to changes in cytoskeletal contractility and cell shape. Here, we tested whether microenvironment-specific modulation of RhoA signaling can restore NP-like morphology and gene expression in NP cells cultured in 2D and in 3D alginate. In 2D monolayer culture, where cells are spread and mechanically activated, pharmacologic inhibition of RhoA with CT04 reduced RhoA activity, decreased actomyosin contractility gene expression, and shifted morphology toward a smaller, more circular phenotype. Bulk RNA sequencing showed that CT04 treatment increased expression of NP phenotypic and matrix-related genes including ACAN, GDF5, CHST3, and MUSTN1 while decreasing expression of catabolic and fibroblast-associated genes including ADAMTS1/9 and COL1, consistent with enrichment of extracellular matrix pathways. In contrast, RhoA activation with CN03 in 2D culture increased actin and phosphorylated myosin light chain intensity but produced limited phenotypic improvement. In 3D alginate, which minimizes integrin-mediated adhesion, baseline actomyosin markers were reduced relative to 2D culture. In alginate, RhoA activation with CN03 increased the amount of actin, phosphorylated myosin light chain, and actomyosin gene expression, yet also promoted a more compact, circular morphology and increased NP markers, including ACAN and KRT19 with repeated dosing. Across culture conditions, increased cell roundness was consistently associated with increased ACAN expression, indicating strong coupling between cytoskeletal state, morphology, and NP matrix programs. Together, these findings demonstrate that RhoA pathway perturbation can promote NP phenotypic gene expression in both 2D and 3D culture, but the direction of optimal modulation depends on the microenvironment, supporting RhoA signaling as a context-dependent therapeutic target for disc regeneration.

SEZ6L2 autoantibodies have been identified in patients with subacute cerebellar ataxia, but the underlying immune mechanisms and pathogenic pathways remain poorly understood. We previously established a C57BL/6 mouse model of SEZ6L2 autoimmunity that recapitulates key features of the disease. Here, we evaluated whether genetic background influences the magnitude and organization of SEZ6L2-directed immune responses. Pilot screening of autoimmune-prone strains identified SJL mice as exhibiting accelerated and enhanced antibody responses following SEZ6L2 immunization. In a large-cohort study, SEZ6L2-immunized SJL mice developed robust and sustained antibody responses, along with antigen-specific CD4 and CD8 T-cell activation. Expanded immune profiling revealed increased CNS infiltration of multiple lymphocyte populations, including CD4 T cells, CD8 T cells, B cells, and dendritic cells, as well as the presence of SEZ6L2-specific B cells within the brain. In addition, SJL mice exhibited strain-specific immunodominant T-cell epitopes distinct from those observed in C57BL/6 mice. Functionally, SEZ6L2-immunized SJL mice developed motor deficits consistent with cerebellar dysfunction. Integration of behavioral outcomes demonstrated a consistent overall impairment, and multivariate analysis revealed that coordinated humoral and cellular immune responses were associated with behavioral deficits. Together, these findings demonstrate that SEZ6L2-directed immune responses produce coordinated adaptive immune activation linked to neurological dysfunction and establish the SJL strain as an enhanced model for studying SEZ6L2 autoimmunity. This model also provides a platform for investigating disease mechanisms and therapeutic strategies.

Lung fibroblasts are key regulators of tissue homeostasis and extracellular matrix (ECM) remodeling, and their aberrant activation drives the progressive parenchymal scarring characteristic of idiopathic pulmonary fibrosis (IPF), a fatal disease with limited therapeutic options. Despite their central pathogenic role, lung fibroblasts are difficult to isolate due to their embedded position within the ECM, and standard in vitro culture conditions may lead to the loss of their native functional and transcriptional characteristics, hampering the study of fibroblast behavior in disease. The transcriptional heterogeneity of lung fibroblast subtypes and the extent to which culture-induced alterations diverge from native tissue signatures remain poorly understood. Here, we integrated single-cell RNA sequencing (scRNA-seq) and spatial transcriptomics of lung tissue from IPF patients and age-matched healthy donors with transcriptomic profiling of cultured fibroblasts collected at passages 1 and 6 after isolation using three optimized protocols: whole lung cell suspension (WLCS), negative fraction enrichment, and outgrowth. Tissue-based analysis identified six transcriptionally distinct mesenchymal subtypes: alveolar, adventitial, inflammatory, peribronchial, CTHRC1+ and smooth muscle cell (SMC). The fibroblast subtype CTHRC1+ represented the most transcriptionally activated pro-fibrotic subtype, showing the greatest upregulation of ECM biosynthesis genes, a prominent role in intercellular communication, and preferential enrichment within fibroblastic foci in IPF lung tissue. Pseudotime trajectory analysis supported a directional transcriptional continuum from alveolar and inflammatory fibroblasts toward the CTHRC1+ state, driven by coordinated activation of pro-fibrotic transcription factors, including RUNX2, CREB3L1, and SCX. In vitro culture progressively reshaped fibroblast transcriptional identity relative to native tissue, with increased collagen and matrix metalloproteinase (MMP) expression during passaging, loss of distinct CTHRC1+ fibroblasts, and gain of alveolar fibroblasts displaying pro-fibrotic activation across all isolation protocols. These findings provide a high-resolution transcriptional map of lung fibroblast heterogeneity in IPF and highlight critical limitations of standard in vitro culture systems for recapitulating native fibroblast diversity, with important implications for the development and evaluation of fibroblast-targeted therapeutic strategies in IPF.

ABSTRACT/SUMMARYVascular remodeling within the developing fetus and placenta is essential for supporting the growth and function of emerging tissues and organs. Pericytes (PCs) play a central role in stabilizing and maturing microvascular networks by extending along endothelial cells (ECs) and reinforcing vessel integrity. In the placenta, as in other organs, PC-EC communication is mediated in part by platelet-derived growth factor-BB (PDGF-BB) signaling, which governs PC differentiation, proliferation, migration, and survival, ultimately enabling their recruitment and retention along capillaries. In this study, we identified progressive PC investment along feto-placental capillaries in both murine and human tissues across gestation, supported by morphological and molecular evidence. Placental PCs displayed phenotypic heterogeneity comparable to that observed in the brain and heart, suggesting conserved diversity across organ systems. In addition to characterizing PC dynamics, we examined the expression of recently identified soluble PDGF Receptor-{beta} (sPDGFR{beta}) isoforms. These variants were detected at the protein and transcript levels in mouse and human placentas, as well as in a murine trophoblast-embryonic stem cell (TESC) differentiation model that recapitulates aspects of early placental vascular development. Within this model, sPDGFR{beta} expression was independent of ADAM10 activity and exogenous growth factors during early vessel formation but was markedly upregulated during hypoxia. To assess how elevated sPDGFR{beta} might influence PDGF-BB signaling, we exposed TESCl-derived vascular networks to excess PDGF-BB with or without a sPDGFR{beta} mimetic. PDGF-BB alone reduced full-length PDGFR{beta} levels while increasing receptor phosphorylation, consistent with known ligand-induced regulatory mechanisms. Inclusion of the sPDGFR{beta} mimetic shifted these responses toward baseline, suggesting a potential modulatory or feedback role for soluble receptor variants. Together, these findings demonstrate that PCs are progressively recruited to placental capillaries and exhibit diverse phenotypes during development, and that soluble PDGFR{beta} isoforms may modulate PDGF-BB signaling in a manner sensitive to oxygen tension. Understanding these mechanisms provides insight into the regulation of placental vascular maturation and may inform strategies to improve human health by targeting disorders rooted in impaired placental development.

Acute kidney injury (AKI) is a serious and common clinical syndrome that currently has no effective treatment. Emerging evidence links coagulation pathways to kidney injury, particularly through coagulation proteases. Protease-activated receptors (PARs) are a family of G-protein coupled receptors (GPCRs) that are activated by proteolytic cleavage of their N termini, exposing a tethered ligand that initiates receptor signaling. PARs have been shown to play a major role in inflammation, vascular regulation, and tissue injury. PARs play key roles in inflammation, vascular regulation, and tissue injury. Previous work from the Hamm laboratory demonstrated that PAR4 contributes to AKI progression, as PAR4 knockout mice were protected in both unilateral ureteral obstruction and ischemia-reperfusion-based models of kidney disease. In this study, we investigated the potential of a PAR4 antagonist, VU6073819, at mitigating AKI progression in an ischemia-reperfusion injury (IRI) mouse model. PAR4 antagonism not only alleviated kidney injury and inflammatory response, but it significantly improved the survival. These findings identify PAR4 as a promising therapeutic target for AKI.

Wolfram syndrome is a rare autosomal recessive disorder caused by pathogenic variants in the WFS1 gene, characterized by early-onset diabetes mellitus, optic atrophy, sensorineural hearing loss, arginine vasopressin deficiency, and progressive neurodegeneration. The condition selectively affects pancreatic {beta} cells and neurons via chronic endoplasmic reticulum (ER) stress, and no proven disease-modifying therapy currently exists. Diabetes mellitus is typically the first manifestation, presenting at a mean age of 6 years as an insulin-dependent phenotype with preserved C-peptide and negative diabetes-related autoantibodies. Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) are well-established agents in the management of type 2 diabetes, augmenting glucose-dependent insulin secretion, suppressing glucagon, slowing gastric emptying, and promoting satiety. Preclinical evidence further suggests that GLP-1 RAs preserve {beta}-cell mass, attenuate ER stress, and confer neuroprotective effects, properties of particular therapeutic relevance to Wolfram syndrome. We conducted a retrospective cohort study of 84 participants with genetically confirmed Wolfram syndrome and insulin-dependent diabetes mellitus enrolled in the Washington University Wolfram Syndrome International Registry and Clinical Study. Clinical data were extracted from medical records; for participants concurrently enrolled in the Tracking Neurodegeneration in Early Wolfram Syndrome study, longitudinal data were obtained from that source as well. Thirty-five percent of eligible participants had received a GLP-1 RA at some point during follow-up. We characterize the prevalence of GLP-1 RA use, documented rationale for initiation, observed effects on glycemic control and visual outcomes, adverse effects, and reasons for discontinuation. No statistically significant changes in hemoglobin A1c (HbA1c) or body mass index (BMI) were observed. Visual acuity declined significantly at two years, consistent with expected disease progression. Gastrointestinal adverse effects were common and contributed to frequent discontinuation. These observational data provide important clinical context and a foundation for future prospective trials evaluating GLP-1 RAs as a potential disease-modifying strategy in Wolfram syndrome.

BackgroundIdiopathic pulmonary fibrosis (IPF) is a progressive and fatal lung disease characterized by aberrantly activated, apoptosis-resistant profibrotic lung (myo)fibroblasts. Prior research has demonstrated that lung fibroblasts from patients with IPF exhibit resistance to DNA damage, suggesting that this behavior contributes to their persistent survival and continuous proliferation. We propose that elevated levels of the DNA damage repair protein RAD51 regulate myofibroblast activation and apoptosis and provide a potential therapeutic target to impede fibrosis progression. MethodsHuman lung fibroblasts were transfected with siRNA against RAD51 or treated with RAD51-specific inhibitor B02 and markers of fibrosis, DNA damage, apoptosis, metabolic reprogramming, and mitochondrial dynamics were assessed. The preclinical efficacy of B02 was evaluated in human precision cut lung slices (PCLS) and in a mouse model of pulmonary fibrosis. FindingsRAD51 expression was significantly upregulated in the lungs and lung fibroblasts of IPF patients. Knockdown or inhibition of RAD51 in fibroblasts reduced profibrotic marker expression, suppressed mTORC1 signaling and mitochondrial function, and increased apoptosis susceptibility. Pharmacological inhibition of RAD51 shifted the profibrotic phenotype towards a fibrosis-resolving state in human and mouse PCLS, and in a bleomycin-induced mouse model of lung fibrosis. InterpretationThe inhibition of RAD51 exerts therapeutic benefits in lung fibrosis by promoting apoptosis. Our findings identify that inhibiting RAD51 with B02 in fibroblasts impairs DNA repair and induces metabolic reprogramming, making it a potential therapeutic target. Research in contextO_ST_ABSEvidence before this studyC_ST_ABSPulmonary fibrosis (PF) is characterized by excessive fibroblast activation and subsequent deposition of extracellular matrix (ECM) proteins, which ultimately disrupt normal lung architecture. A significant contributing factor to the pathogenesis of pulmonary fibrosis is the presence of fibroblasts that are resistant to apoptosis, preventing normal wound healing. Recent studies highlight the DNA repair protein RAD51 as effective in protecting fibroblasts from death induced by chemotherapy and ionizing radiation. These finding suggested that RAD51 could have a role in fibroblast activation and apoptosis resistance in pulmonary fibrosis. Added value of this studyWe demonstrated that RAD51 is important for maintaining apoptosis-resistant fibrotic fibroblasts and their metabolic abnormalities. Our findings indicated that TGF{beta}-mediated upregulation of RAD51 reduces DNA damage, activates multiple pathways related to fibroblast activation and proliferation, and induces metabolic reprogramming, ultimately regulating apoptosis. Mechanistically, RAD51 inhibition enhanced p53 acetylation at lysine 120 and upregulated the expression proapoptotic proteins PUMA/BAK in mitochondria, promoting apoptosis. Pharmacological inhibition of RAD51 using the specific inhibitor B02 during the fibrotic phase of experimental lung disease effectively ameliorated pulmonary fibrosis. Implications of all the available evidenceOur findings establish that RAD51 plays an important role in the survival of apoptosis-resistant fibrotic fibroblasts. We propose that reducing RAD51 expression leads to the metabolic reprogramming of activated fibroblasts, resulting in decreased mitochondrial respiration, reduced ATP levels, and diminished glycolysis or glutaminolysis. These observations suggest that targeting energy metabolism through RAD51 inhibition could be a viable strategy to enhance apoptosis, thereby creating a therapeutically targetable pathway in fibrotic cells. These findings highlight the potential of RAD51 as a therapeutic target for the treatment of IPF.

BackgroundGastroesophageal reflux disease (GERD) is highly prevalent in systemic sclerosis (SSc) and frequently persists despite proton pump inhibitor (PPI) therapy. However, the mechanisms underlying PPI-refractory GERD in SSc remain incompletely understood. MethodsWe conducted a singlel7lcentre, retrospective study of adults with SSc who underwent ambulatory pH-multichannel intraluminal impedance (pH/MII) monitoring while receiving twicel7ldaily PPI therapy (2021-2025). Esophageal motility (highl7lresolution manometry, HREM) and gastric emptying scintigraphy were integrated to examine associations between gastro-esophageal dysmotility and reflux phenotypes. ResultsThirty patients were included, of whom 67% had PPI-refractory reflux symptoms and 33% were undergoing pre-lung transplantation evaluation. Refractory GERD was present in 29/30 patients (97%) based on Lyon 2.0 classification, with conclusive evidence in 53% and borderline evidence in 43%. Esophageal dysmotility was identified in 80%, most commonly absent contractility (67%), and was associated with impaired reflux clearance, reflected by longer acid clearance times (2.20 [1.15-3.75] vs 1.15 [0.43-1.90] min) and prolonged reflux episode duration (16.60 [4.38-40.63] vs 1.95 [0.53-20.43] min). Gastric dysmotility was identified in 60.7% and was associated with an increased reflux episode burden (51.00 [30.00-81.50] vs 25.00 [21.00-54.00] episodes/24h). ConclusionsPPIl7lrefractory GERD is nearly universal in this SSc cohort and reflects heterogeneous, quantifiable abnormalities across the foregut, including impaired esophageal clearance and increased reflux burden related to gastric retention. These findings support integrated physiologic evaluation to define reflux mechanisms, inform risk stratification (including lung transplantation), and guide targeted, mechanism-based therapies beyond acid suppression.

Sepsis is a life-threatening dysregulated response to infection, the heterogeneity of which precludes effective targeted therapies. To address this, we created a transcriptomic atlas of publicly available adult sepsis data, on which we performed molecular subtyping and identified potential subtype-specific drug repurposing opportunities. In total, we harmonized data from 3,713 samples across 28 datasets, of which 2,251 were from sepsis patients. Using this data, we identified four molecular subtypes of sepsis (C1 - C4) by clustering the sepsis samples based on expression differences in immune-and lipid-related genes. We next identified gene signatures unique to each molecular subtype. Pathway analysis of these signatures revealed patterns of immune exhaustion and metabolic dysregulation in C1, suggesting potential benefit from corticosteroid treatment. C2 had the youngest patient population and the lowest mortality, and C2 expression patterns were often anti-correlated with those of C1. C3 was enriched for inflammatory and cellular stress pathways, while the highest mortality subtype, C4, showed evidence of immunosuppression and metabolic reprogramming. Gene and pathway-level analysis of our molecular subtypes statistically correlated with results from analysis of 28-day mortality, with the best (C2) and worst subtypes (C4) exhibiting similar molecular dysregulation as survivors and non-survivors, respectively. For each subtype, we then evaluated potential targeted therapies. Using a large-scale pharmacogenomics database, we identified drugs targeting the subtype gene signatures and assessed the potential clinical impacts of these drugs. We identified several potential candidate therapies for each molecular subtype, including possible responsiveness to Methylene Blue therapy for patients from our highest mortality subtype, C4. Notably, our drug repurposing analysis revealed a significant representation of anti-inflammatory monoclonal antibody therapies across molecular subtypes. The anti-correlated signatures in C1 and C2 suggest that monoclonal antibody therapies may not be effective for patients in both subtypes, which may explain why prior clinical trials have been unsuccessful. Altogether, our detailed molecular subtyping and analysis identify potential drug targets within each molecular subtype, with implications for future precision medicine for sepsis.

An efficacious blood-stage malaria vaccine would serve as a highly useful public health tool alongside licensed vaccines targeting the pre-erythrocytic life cycle stage of the Plasmodium falciparum parasite. RH5 is the leading blood-stage malaria vaccine candidate antigen due to its highly-conserved sequence and non-redundant role in merozoite invasion of red blood cells. Following encouraging immunogenicity data in UK and Tanzanian Phase Ia/b vaccine trials, RH5-based vaccines have progressed to Phase IIb evaluation in Burkina Faso in recent years. Here, we report a Phase Ia clinical trial in malaria-naive UK adults to assess the safety and immunogenicity of the malaria vaccine candidate RH5.1 soluble protein with Matrix-M adjuvant using two different booster dosing regimens: 10-10-10 micrograms versus 50-50-10 micrograms RH5.1, both delivered in a 0-1-6-month schedule with 50 micrograms Matrix-M adjuvant per dose (ClinicalTrials.gov NCT06141057). A total of n=24 participants were recruited to this study, with n=23 completing all follow-up visits through to 1 year following final vaccination. The RH5.1/Matrix-M formulation was well-tolerated in this population, with injection site pain, myalgia and fatigue being the most commonly reported symptoms up to 7 days post-vaccination. There were no serious adverse events, adverse events of special interest, or suspected unexpected serious adverse reactions reported over the course of the trial. Both vaccination regimens were similarly immunogenic; no differences were observed in peak anti-RH5.1 serum IgG concentrations, in vitro functional anti-parasitic activity, avidity, or durability. Our findings build on other observations from clinical trials of adjuvanted RH5.1 indicating that humoral immunogenicity can be enhanced by delaying the final booster vaccination, but that there is limited impact of fractionation of the final dose. These insights can help to guide the next steps of multi-antigen, multi-stage malaria vaccine development in malaria-endemic settings.

Gastrointestinal (GI) dysmotility is a highly prevalent and clinically significant feature of Rett syndrome (RTT), yet its underlying mechanisms remain poorly defined. Here, we investigated these mechanisms of GI dysmotility in a Mecp2-null mouse model of RTT. First, we observed that MeCP2 was expressed in murine myenteric ganglia, including in enteric neurons and that Mecp2-null males developed maturation-associated functional regression in their GI motility. In dysmotile mice, longitudinal muscle-myenteric plexus tissue showed marked reductions in enteric Bdnf isoforms IV, VI, and II, whereas expression of the BDNF receptor isoforms TrkB.FL and TrkB.T1 was not significantly altered, consistent with reduced enteric BDNF-TrkB signaling. Despite impaired GI motility, Mecp2-null mice showed no significant changes in total enteric neuronal density, nitrergic neuronal abundance, or expression of Nos1, Chat, and Uchl1. In contrast, Vip expression was significantly reduced, while expression of VIP receptor genes: Vipr1 and Vipr2 was increased, indicating disrupted VIPergic signaling. Integration with publicly available enteric single-cell/nucleus datasets and targeted qRT-PCR further suggested altered inhibitory neuronal subtype composition, with reduced Vip+ Cartpt+ signatures and increased Nfia expression, suggesting that MeCP2 loss differentially affects distinct inhibitory neuronal subpopulations. Finally, conditional loss of TrkB.FL in neural crest-derived cells reduced Vip expression without recapitulating the full Mecp2-null VIPergic phenotype, indicating that impaired BDNF-TrkB signaling contributes to, but does not completely explain, the GI dysmotility in this model of RTT. Together, these findings identify enteric BDNF-TrkB and VIPergic dysfunction as key mechanisms underlying GI dysmotility in RTT.

Patients with myasthenia gravis (MG) may produce autoantibodies neutralizing type I interferons (AAN-I-IFN), which have been shown to underlie severe viral diseases, including critical COVID-19 pneumonia, in patients without MG. We studied an international cohort of 85 unvaccinated SARS-CoV-2-infected MG patients with no antiviral treatment. Hypoxemic pneumonia occurred in 48 of these patients, including 22 (45.8%) with AAN-I-IFN, which neutralized both IFN-2 and IFN-{omega} in 14 (29.2%) patients. Six (16.2%) of the remaining 37 patients had AAN-I-IFN, which neutralized both IFN-2 and IFN-{omega} in three patients. The risk of hypoxemic pneumonia was greater in MG patients with AAN-I-IFN neutralizing 10 ng/mL of both IFN-2 and IFN-{omega} (odds ratio and 95% confidence interval (OR [95% CI]): 12.7 [2.1-78.9], p=0. 0010) or IFN-2 at any dose (4.7 [1.5-15.0], p=0.0054) than in those without such autoantibodies. The risk of AAN-I-IFN production was much higher in MG patients than in the general population (28.9 [10.8-77.7], p=4.9x10-27). Fourteen patients had thymoma, which increased the risk of AAN-I-IFN (64% versus 27%, (OR [95% CI]: 5.6 [1.6-19.4], p=0.0050) and hypoxemic pneumonia (9.2 [1.9-44.2]; p=0.0019). Thymoma is, thus, associated with a higher risk of producing AAN-I-IFN, and these autoantibodies are associated with a higher risk of developing life-threatening COVID-19 pneumonia in patients with MG.

Pregravid obesity is associated with longterm immune alterations in the offspring; however, the mechanisms remain poorly defined. To address this gap, we investigated the impact of spontaneous pregravid obesity, independent of obesogenic diet, on fetal immune ontogeny in a rhesus macaque model. Using spectral flow cytometry, multiplex cytokine profiling, functional stimulation assays, and singlecell RNA sequencing, we profiled immune composition, function, transcriptional profiles, and intercellular communication in umbilical cord blood as well as fetal spleen and lung. Pregravid obesity was associated with altered fetal organ growth, elevated inflammatory mediators, altered frequencies of immune cell populations, and hyperresponsiveness to stimulation by splenic and lung leukocytes. Singlecell transcriptomic analyses revealed tissuespecific reprogramming of innate immune cells, including heightened inflammatory, migratory, and metabolic signatures with impaired antigen presentation. Moreover, there was evidence of impaired T cell differentiation, premature effector differentiation, and B cell dysfunction. Cell-cell communication analysis identified loss of tolerogenic signaling and enhanced proinflammatory pathways across spleen and lung myeloid cells. These findings demonstrate that spontaneous pregravid obesity fundamentally reshapes fetal circulating and tissueresident immune cells, providing mechanistic insight into the increased susceptibility to infection, respiratory diseases, and immune dysregulation observed in offspring of mothers with obesity.