Lupus nephritis (LN) requires long-term immunosuppressive therapy, which is often associated with severe systemic side effects. Therefore, new therapeutic strategies that maintain high efficacy while minimizing adverse effects are essential. Although nanomedicine has advanced systemic and kidney-targeted drug delivery, a reliable method for glomerulus-specific delivery is lacking. Collagen IV (Col4)-alpha 3, located in the glomerular basement membrane at the blood-tissue interface through fenestrated capillary endothelium, represents an ideal target for glomeruli delivery. Herein, we developed a novel liposomal nanoparticle conjugated with a Col4-alpha 3-binding peptide (Col4-α3-NPs) for selective glomerular targeting. Prednisolone-loaded Col4-α3-NPs were administered to lupus-prone mice twice weekly for 8 weeks. Kidney injury and function were evaluated biweekly, and renal immune cell populations were analyzed by flow cytometry at study completion. The results show that rhodamine-labeled NPs predominantly accumulate in kidney glomeruli 48 h after intravenous injection. The Col4-NP system demonstrated stable and prolonged release of the encapsulated drug for over 48 h. Lupus-prone mice treated with prednisolone-loaded Col4-NPs showed significantly improved renal function and histology, including a 30% increase in glomerular filtration rate, a 56% reduction in proteinuria, and decreased IgG deposition and fibrosis. Notably, treatment also enhanced renal regulatory T cell populations. These findings suggest that glomerulus-targeted Col4-α3-NPs hold significant translational promise. This platform may offer an effective, site-specific treatment for LN while minimizing systemic side effects and could be adapted for other glomerular diseases requiring targeted therapy.
AMP-activated protein kinase (AMPK), a heterotrimeric serine/threonine protein kinase consisting of the catalytic α-subunit and regulatory β- and γ-subunits, regulates endothelial homeostasis. Consequently, it has emerged as a target for pharmacological activators in the treatment of endothelial dysfunction. However, the efficiency of these agonists may differ depending on the expression of different AMPK subunit isoforms in different cells and tissues, as these isoforms may form AMPK complexes with distinct activation profiles. This study compares the effects of three direct AMPK activators in endothelial cells: MK-8722, a pan-AMPK activator, SC4, an intermediate activator with preference for AMPKα2, and A-769662, a β1-specific compound. We demonstrate that MK-8722 (0.1 µM to 10 µM) induces a robust and sustained, short- and long-term activation of AMPK as evidenced by the phosphorylation of acetyl-CoA carboxylase (ACC) and the inhibition of the mechanistic target of rapamycin complex 1 (mTORC1) pathway. On an equimolar basis, MK-8722 was significantly more potent than SC4 and A-769662. This was associated with a significant antiviral effect of MK-8722 against herpes simplex virus type 1 (HSV-1), whereas SC4 and A-769662 had no effect. At 10 µM, MK-8722 led to energy depletion and increased formation of mitochondrial and cytosolic reactive oxygen species (ROS) due to inhibition of mitochondrial complex I. Under these conditions, LKB1-mediated AMPK activation was observed but was not functionally relevant. We propose that the strong activation of AMPK by MK-8722 is related to the presence of different AMPK heterotrimers in endothelial cells. Therefore, targeting endothelial dysfunction pharmacologically may require pan-AMPK activators.
Senescent cell accumulation and fibrosis play a fundamental role in kidney ageing. Our aim was to determine whether the angiotensin IV/insulin-regulated aminopeptidase (IRAP) axis of the renin-angiotensin system contributes to renal function decline, fibrosis and senescent cell accumulation in aged mice. We studied the role of IRAP in kidney aging using IRAP knockout mice, as well as in wildtype mice treated with an IRAP inhibitor. Complementary proximal tubule and collecting duct cell models were used to determine the mechanisms by which IRAP inhibition exerts protective effects. Glomerular filtration rate declined by 25% in wild-type mice between 3-23 months of age, concomitant with marked increases in albumin excretion, glomerulosclerosis, tubulointerstitial fibrosis and accumulation of senescent cells in the proximal tubules of the kidney. IRAP knockout mice were protected against age-related decline in glomerular filtration rate, renal fibrosis and senescence burden compared to age-matched wildtype mice. IRAP inhibition for 4 weeks (HFI-419, 500 ng/kg/min) in 28-month-old wild-type mice similarly prevented age-related decline in glomerular filtration rate and attenuated expression of cellular senescence markers. Using an in vitro model of cultured proximal tubule cells, IRAP inhibition mitigated the pro-senescent effects of oxidative stress. This was associated with shifts in the metabolic phenotype of proximal tubular cells, indicating senoprotective effects of IRAP inhibition may be mediated in part via mitochondrial function. These studies provide evidence that IRAP deficiency is protective against chronic renal cellular senescence, fibrosis and functional decline. Therefore, IRAP inhibition has therapeutic potential to attenuate pathological cardiorenal ageing through senoprotective mechanisms.
Synphilin-1 is a protein that interacts with α-synuclein and has been implicated in Parkinson’s disease. However, the cellular and molecular mechanisms underlying the effect of synphilin-1 in Parkinson’s disease remain poorly understood. This study aimed to elucidate the molecular function of synphilin-1 using integrated transcriptomic and proteomic in silico analyses, followed by in vitro validation. Synphilin-1 overexpression enhanced cell viability and attenuated pathways associated with cell death. Among the identified regulatory molecules, p53 emerged as a key mediator linking synphilin-1 to suppression of anoikis. Notably, p53 expression demonstrated predominant nuclear localisation in midbrain tissues of individuals with Parkinson’s disease. These findings suggest that synphilin-1 promotes cell survival by suppressing p53-mediated anoikis. This regulatory relationship could be crucial for understanding neuroprotective or pathological mechanisms in Parkinson’s disease.
Sodium-Glucose Transport Protein 2 inhibitors (SGLT2i), initially developed as antidiabetic agents and now established as foundational therapies for heart failure, have also shown antihypertensive effects in clinical trials involving patients with diabetes and heart failure. However, the underlying mechanisms remain incompletely understood. Given the diverse roles of arachidonic acid (AA) and its metabolites in blood pressure regulation, we investigated the antihypertensive effects of SGLT2i in hypertensive patients and an animal model, and explored whether modulation of AA metabolism contributes to these effects. We first confirmed the antihypertensive effects of SGLT2i in a retrospective cohort study and spontaneously hypertensive rats (SHRs). Targeted metabolomic analysis of plasma and tissues from SHRs identified 20-hydroxyeicosatetraenoic acid (20-HETE) originating from the renal cortex as a key metabolite modulated by SGLT2i. Among the enzymes responsible for 20-HETE production, CYP4A but not CYP4F was found to be downregulated by dapagliflozin at both mRNA and protein levels. Immunofluorescence colocalization further localized this effect to proximal tubular epithelial cells, where SGLT2i reduced CYP4A expression and subsequent 20-HETE production, leading to attenuated renal inflammation, fibrosis and blood pressure elevation. Together, these findings not only confirm the antihypertensive effects of SGLT2i but also delineate a novel antihypertensive mechanism by which lower blood pressure, demonstrating that modulation of arachidonic acid metabolism contributes partially to blood pressure-lowering effects.
Dysregulated lipid metabolism is implicated in renal injury associated with diabetic nephropathy, acute kidney injury, chronic kidney disease, nephrotic syndrome, and renal cell carcinoma. However, its causal role and mechanisms remain ambiguous. Mitochondria-associated ER membranes (MAMs) are contact sites between the endoplasmic reticulum and mitochondria that facilitate the integration of lipid trafficking, mitochondrial metabolism, calcium signaling, and redox homeostasis within cells. Recent evidence from patient biopsies and experimental renal models suggests that altered MAM integrity is linked to ectopic lipid deposition, mitochondrial dysfunction, oxidative stress, and renal injury. The present review examines evidence suggesting that MAM dysregulation may contribute to the abnormal metabolism of phospholipids (PLs), ceramides, cholesterol, fatty acids, and triglycerides in renal cells, thereby addressing a gap between previous reviews on renal lipotoxicity and those focusing on MAM-dependent calcium signaling in kidney diseases. Key mechanisms include impaired PL transfer with disrupted cardiolipin remodeling, ceramide-associated mitochondrial injury, defective fatty acid oxidation, and acyl-CoA synthetase long-chain family member 4-mediated PL peroxidation, leading to renal ferroptosis. Direct evidence for MAM-regulated lipid droplet degradation in the kidney is limited; thus, findings from non-renal cells are differentiated from kidney-specific observations. MAM-associated proteins have emerged as potential therapeutic targets in preclinical studies. However, renoprotective effects of sodium-glucose cotransporter 2 inhibitors and glucagon-like peptide-1 receptor agonists related to MAMs remain indirect and necessitate validation. Restoring the structural and functional integrity of MAMs could represent a promising strategy to mitigate lipid-induced renal injury.
Ribosomal protein S3 (RPS3) is an essential structural component of the 40S ribosomal subunit, yet growing evidence highlights crucial extraribosomal roles in genome maintenance, cell-cycle control, and immune signaling. Dysregulation of RPS3 contributes to diverse human disorders, including cancer, inflammatory diseases, neurodegeneration, and resistance to antimicrobial and anticancer therapies. As a cofactor of NF-κB and a participant in DNA damage responses, RPS3 occupies a node that integrates stress signaling with transcriptional reprogramming, enabling both protective and pathological outcomes. The present review critically evaluates mechanistic insights into RPS3 biology, emphasizing recent findings that delineate its context-dependent effects, discrepancies across models, and remaining gaps that restrict translational applications. Understanding these complexities is essential to assess RPS3's potential as a biomarker and therapeutic target.
Pregnancy is associated with a unique and dynamic gut microbiota profile that supports fetal growth and neurodevelopment. Psychotropic drug-gut microbiota interactions are documented in the general population, yet less well described in pregnant women. Research has independently linked both perinatal psychotropic exposure and alterations to the maternal gut microbiome with potential changes to offspring neurodevelopment; therefore, it is plausible that similar interactions occur during pregnancy where they may influence maternal-fetal signaling pathways relevant to brain development. The aim of the present review is to explore the potential for interactions between perinatal psychotropic exposure and the maternal gut microbiota to shape long-term offspring neurodevelopment and psychiatric outcomes. By focusing on antidepressants, opioids/analgesics, and psychostimulants, potential mechanistic insights and gaps in the literature are highlighted to inform future research directions and therapeutic interventions. Collectively, the present review proposes the maternal gut microbiota as a previously underexplored yet significant modulator of neurodevelopment in the context of psychotropic drug exposure.
Maternal microchimerism (MMc) encompasses the transfer and long-term persistence of maternal cells within the offspring-beginning in utero via the placenta and continuing after birth through breastfeeding. Once viewed as an immunological oddity, MMc is now recognized as a dynamic, multifaceted process that permeates the entire field of developmental physiology. Maternal cells, including tissue-specific, immune, and stem/progenitor populations, are not mere passengers; they integrate and functionally engage within fetal and neonatal tissues. Remarkably, MMc brings both protection and risk: supporting immune maturation, defense against infection, and even compensating for immunodeficiencies, while also contributing to the pathogenesis of autoimmune and inflammatory diseases in vulnerable hosts. Additionally, MMc may be involved also in modulation of the tolerance/rejection balance in transplant patients. In the present review, we synthesize the mechanisms of MMc establishment, compare the fetal and neonatal (breast milk-mediated) routes, and critically evaluate its effects across organ systems. Special focus is given to breast milk as a source of diverse maternal cells with complex physiological impacts extending into adulthood, positioning MMc as a true double-edged legacy in mammalian biology.
Muscle weakness and fatigue feature in many diseases, but the underlying pathophysiology can be difficult to study in vivo. In patients with the chronic autoimmune disease systemic sclerosis (SSc), considerable disability results from small-vessel vasculopathy and progressive fibrosis. Alongside cardiopulmonary limitations on exercise capacity, there is increasing evidence of peripheral dysfunction. In a study reported in this issue, Layec and colleagues investigate this in exercising skeletal muscle in vivo using a combination of phosphorus magnetic resonance spectroscopy (31P MRS) and proton magnetic resonance spectroscopy (1H MRS). The 31P MRS abnormalities (a bigger change in phosphocreatine (PCr) concentration during exercise and slower post-exercise PCr recovery) reflect impaired mitochondrial ATP synthesis, and the larger change in deoxymyoglobin concentration measured by 1H MRS (implying lower myocyte PO2) implicates a defect in O2 supply rather than in mitochondrial O2 use. This major contributor to impaired exercise tolerance would be difficult to establish using classical methods of biopsy and exercise physiology, which shows the power of non-invasive measurement modalities to probe the pathophysiology of complex conditions.
Physical inactivity and reduced cardiorespiratory fitness are major public health concerns worldwide. In recent decades, the modern western diet has undergone a dramatic shift toward ultra-processed foods (UPFs) that are rich in inorganic phosphate (Pi) additives used as preservatives, emulsifiers, leavening agents, and flavor enhancers. Unlike organic phosphorus found in natural foods, inorganic Pi additives are nearly completely absorbed in the gastrointestinal tract, contributing to habitual Pi intake that exceeds the recommended daily allowance by two- to three-fold in many western populations. Accumulating evidence suggests that this chronic Pi excess may impair skeletal muscle energetics and exercise capacity. In population-based cohort studies, higher serum Pi has been independently associated with reduced physical activity and increased sedentary time. Using 7-Tesla 31P magnetic resonance spectroscopy, higher dietary Pi intake has been correlated with lower resting muscle ATP synthesis and greater phosphocreatine depletion during exercise. Experimental studies have shown that a high-Pi diet reduces maximal oxygen uptake, treadmill endurance, and fat oxidation, and downregulates skeletal muscle fatty acid metabolism genes. At the cellular level, elevated Pi promotes muscle atrophy via autophagy and oxidative stress and reduces mitochondrial membrane potential. Endocrine mediators, including elevated fibroblast growth factor 23 and suppressed Klotho, may further contribute to muscle dysfunction. The present review synthesizes current evidence linking UPF consumption, dietary Pi excess, and exercise intolerance, with focus on skeletal muscle dysfunction, including impaired contractile mechanics, disrupted energy metabolism, and mitochondrial injury, as potential mechanisms, and highlights future directions for research and public health intervention.
Macrophages play a major role in immune responses and in the maintenance of tissue homeostasis. Most of our knowledge of macrophage biology comes from mouse studies, which have revealed the existence of distinct subpopulations differing in origin, life cycle and tissue-specific features, as well as the influence of tissue perturbations on macrophage heterogeneity. Here, we review the evidence supporting the conservation of these principles in human macrophages, along with the methodological approaches employed, including omics analyses of macrophages from clinical samples, human transplantation studies and studies of monogenic mutations. We also focus on the macrophage populations that are present in human secondary lymphoid organs-namely the spleen, lymph nodes, and tonsils. While some organ-specific features are shared with their mouse counterparts, we highlight important differences between mouse and human lymphoid tissue macrophages in their functional specialization.
Streptococcus pneumoniae remains a leading cause of lower respiratory tract infections and pneumonia-related mortality worldwide. Although neutrophil recruitment is essential for pneumococcal containment, excessive and dysregulated neutrophilic inflammation can drive severe lung injury and acute respiratory distress syndrome. Specialized pro-resolving mediators, such as Resolvin D5 (7S,17S-dihydroxy-4Z,8E,10Z,13Z,15E,19Z-docosahexaenoic acid; RvD5), are produced in the lungs and have the potential to promote pathogen clearance and limit inflammatory injury. Using a mouse model of severe pneumococcal pneumonia, we investigated the actions of RvD5 on disease progression. Exogenous RvD5 was administered either at the time of infection or post-infection together with the antibiotic ceftriaxone. Outcomes measured included lung neutrophil accumulation, bacterial burden, neutrophil activation markers, and indices of alveolar barrier integrity. Complementary in vitro assays were performed to assess the effects of RvD5 on human neutrophil phagocytosis and activation by LTB4. When administered at the time of infection, RvD5 reduced neutrophil accumulation in bronchoalveolar lavage (BAL) and lung tissue and enhanced clearance of S. pneumoniae. RvD5 decreased neutrophil activation marker expression and lowered total protein levels in BAL fluid, consistent with reduced inflammatory lung injury. When administered post-infection together with ceftriaxone, RvD5 significantly reduced lung neutrophil numbers and barrier disruption compared with antibiotic treatment alone. In vitro, RvD5 enhanced phagocytic uptake and intracellular killing of bacteria by human neutrophils, and blunted secondary calcium mobilization responses to LTB4. In summary, these findings indicate that RvD5 can initiate pro-resolving mechanisms adjunctive to antibiotics to enhance bacterial clearance and limit inflammation-driven lung injury in severe pneumococcal pneumonia.
Cardiovascular diseases are the leading cause of mortality worldwide, with atherosclerosis and formation of arterial plaques being a major underlying cause. Rupture or erosion of the plaque fibrous cap can result in thrombus formation, arterial occlusion, and a stroke or myocardial infarction. Plaque changes, and endothelial cell barrier leakiness, may result in material leakage, including proteins and fragments into plasma either directly or in extracellular vesicles (EVs). Here, we report comparative LC-MS/MS analyses of plasma-derived EVs and plasma from subjects with impaired vascular status and healthy controls. Analysis of plasma-derived EVs detected 7228 peptides and 763 proteins, with 87 proteins being differentially abundant with these including arterial-cell species. Sub-group analysis based on biological sex showed no statistically significant differences for males, whereas females exhibited eight differentially expressed proteins. Subject age effects were minimal. Plasma analysis detected 4366 peptides and 497 proteins, with 188 proteins being significantly altered in abundance between the groups. Subgroup analysis by biological sex revealed 103 differentially expressed proteins in females and 84 in males. No differences were detected in specific collagen fragments. Gene Set Enrichment Analysis revealed altered biological processes related to immune regulation, humoral immune response, proteolysis, and cellular components including plasma lipoprotein particle, extracellular space, and membrane-associated structures. KEGG pathway analysis emphasized enrichment of pathways linked to complement and coagulation cascades, platelet activation, focal adhesion, endocytosis, and inflammation. Together, these data illustrate the potential of LC-MS/MS to examine the role of inflammation and arterial wall cells in shaping the proteome of EVs and plasma in health and disease.
Maintaining genome integrity is essential for survival across all forms of life. Consequently, DNA damage response (DDR) mechanisms are evolutionarily ancient and broadly conserved. Despite their importance as major pathogens of humans, plants, and animals, fungal DDR mechanisms have primarily been studied as model systems to simplify and advance our understanding of DDRs in humans. Antifungal resistance is a major contributor to mortality from human fungal infections, which are associated with an estimated 3.8 million deaths annually. The ability of fungi to balance spontaneous production of beneficial mutations with the preservation of genomic integrity has emerged as a potential mechanism underlying the acquisition of antifungal resistance. In addition, several components of DNA damage repair pathways play direct roles in the virulence of fungal pathogens. In the present review, we provide an overview of DDR pathways, their function and conservation, and highlight specific roles in contributing to genome plasticity, adaptation, virulence, and the emergence of antifungal resistance.
Dialysis-related peritoneal fibrosis (PF) is a complication of peritoneal dialysis (PD) that leads to ultrafiltration failure and poor technique survival. Currently, no effective therapeutic strategies are available for PF. Protein arginine methyltransferase 5 (PRMT5), a major epigenetic regulator catalyzing symmetric dimethylation of arginine residues, has been implicated in fibrotic disorders. However, its role in PD-related PF remains entirely unexplored. In the present study, we demonstrate aberrant PRMT5 overexpression in peritoneal samples from PD patients with ultrafiltration failure as well as in murine PF models, in which PRMT5 colocalized with activated fibroblasts and α-SMA-positive myofibroblasts. To further elucidate the specific role of PRMT5, we generated fibroblast-specific PRMT5 knockout mice and established two murine PF models that recapitulate the clinical phenotype. Genetic PRMT5 inhibition attenuated histopathological damage, extracellular matrix deposition, angiogenesis, and inflammatory infiltration induced by high-glucose PD fluid or chlorhexidine gluconate, thereby improving peritoneal transport function. In vitro, we found genetic PRMT5 inhibition mitigated high-glucose-induced mesothelial-to-mesenchymal transition and inflammatory cytokine secretion. Furthermore, pharmacological inhibition of PRMT5 using selective PRMT5 inhibitor EPZ015666 also exhibited therapeutic efficacy in vivo. Mechanistically, our data implicate a PRMT5-mediated inflammation-angiogenesis axis in PF progression. Collectively, our findings establish PRMT5 as a pivotal, druggable epigenetic regulator in dialysis-related PF and provide a compelling rationale for clinical development of PRMT5-targeted strategies to prevent PF.
Restrictive cardiomyopathy (RCM) is characterized by pronounced cardiac fibrosis (CF), leading to ventricular stiffening and diastolic dysfunction. While cardiomyocyte (CM) mutations are known triggers, the mechanisms initiating profibrotic signaling remain elusive. This study investigates the role of CM-derived exosomes and specific transfer RNA-derived small RNAs (tsRNAs) in this pathogenic intercellular communication. Using a cTnIR193H knock-in mouse model, we observed pronounced CF prior to the onset of heart failure, without significant CM apoptosis. This primary fibrotic response was mediated by a paracrine mechanism, as conditioned medium from mutant CMs was sufficient to activate fibroblasts. Subsequent small RNA sequencing of CM-derived exosomes identified the tRNA-derived fragment 5'tiRNA-GluCTC as a significantly enriched species. Functional studies established this RNA as a critical mediator, demonstrating that its overexpression exacerbated fibrotic responses in vitro and induced fibrotic remodeling in wild-type mice, while its inhibition via a cardiac-targeted Adeno-associated virus sponge attenuated fibroblast activation and alleviated fibrosis in RCM mice. Mechanistically, 5'tiRNA-GluCTC is transferred to fibroblasts, directly targets the 3'UTR of Foxq1 to repress its expression, and consequently activates the Smad3/p-Smad3 signaling cascade. Collectively, these results delineate a 5'tiRNA-GluCTC/Foxq1/Smad3 signaling axis that drives fibrosis in RCM, uncovering a previously uncharacterized signaling cascade with therapeutic potential.
