American Journal of Pathology最新文献

This study evaluated the function of peroxisome proliferator-activated receptor α (PPARα) in vascular endothelial cells (ECs) under physiological and disease conditions. EC-specific PPARα conditional knockout (PPARα^ECKO) and transgenic (PPARα^ECTG) mice were generated. Retinal vascular density and avascular area were evaluated in Griffonia simplicifolia isolectin B4-stained retinas. Endothelial progenitor cells were quantified using flow cytometry. Vascular leakage in streptozotocin-induced diabetic animals was evaluated by Evans Blue. The mitochondrial function and morphology were evaluated by a Seahorse XF Pro analyzer and immunofluorescence staining. Cell senescence was assessed by a senescence-associated β-galactosidase activity assay and postnatal day 21 expression. A significant reduction in the retinal vessel length and vascular mesh density was found in PPARα^ECKO mice. Relative to PPARa^flox-KO mice with oxygen-induced retinopathy (OIR), PPARα^ECKO OIR retina showed enlarged avascular areas and decreased endothelial progenitor cell number, whereas PPARα^ECTG mice showed reduced avascular areas in the OIR retina. Compared with diabetic PPARa^flox-KO mice, diabetic PPARα^ECKO mice showed declined electroretinographic amplitudes, decreased retinal thickness, and increased retinal vascular leakage. PPARα deficiency exacerbated, whereas PPARα activation alleviated, mitochondrial dysfunction in ECs exposed to diabetic stressors. PPARα^-/- ECs developed senescence, prominent oxidant-induced mitochondria fragmentation, and down-regulation of translocase of outer mitochondrial membrane 20 and peroxisome proliferator-activated receptor γ coactivator 1α, relative to wild-type ECs. These results suggest that PPARα in microvascular ECs regulates retinal vascular development and protects ECs against diabetes/hypoxia-induced vascular dysfunction through mitochondrial protective and anti-senescence activities.

Neonatal thymectomy (TX) has been known to induce experimental autoimmune disease models in mice for over half a century. The thymic microenvironment, including thymic epithelial cells (TECs), plays a crucial role in establishing self-tolerance in T cells. However, the extent to which the dynamic changes in the neonatal thymic environment contribute to the onset of autoimmunity remains incompletely understood. In this study, the detailed alterations in the neonatal thymus and peripheral lymphoid organs were analyzed using a mouse model of primary Sjögren disease. Mice treated with TX at 3 days after birth (day 3-TX) exhibited significantly more severe autoimmune pathology than those treated with TX at 7 days after birth. Around day 3, T-cell differentiation and the expansion of TECs, particularly medullary TECs, were markedly accelerated in the neonatal thymus. Furthermore, in day 3-TX mice, the expansion of peripherally induced regulatory T (Treg) cells was impaired, along with the loss of thymic-derived Treg cell output that typically undergoes robust expansion around day 3 after birth. The suppressive activity of Treg cells from day 3-TX mice was significantly impaired compared with that of control Treg cells. These findings suggest that the neonatal thymic environment plays a critical role in regulating peripheral immune tolerance and may influence the pathogenesis of autoimmune diseases.

Ameloblastoma (AM), a locally aggressive odontogenic tumor, exhibits elusive pathogenesis. Here, optic atrophy 1 (OPA1)-mediated mitochondrial hyperfusion was identified as a driver of tumor stemness and progression. Single-cell transcriptomics of primary AM specimens revealed mitochondrial fusion^High epithelial subpopulations exhibiting enriched stemness pathways. A striking up-regulation of OPA1 was observed in AM tissues, establishing a robust correlation between elevated OPA1 expression and up-regulated stemness markers, whereas functional experiments demonstrated that OPA1 overexpression amplifies self-renewal capacity and invasive aggression in hTERT⁺-AM cells. Mechanistically, mitochondrial hyperfusion suppresses Hippo signaling, enabling yes-associated protein 1 (YAP1) nuclear translocation and TEAD-dependent transcription. OPA1-overexpressing cells exhibited robust nuclear YAP1 enrichment, driving stem-like expansion. Critically, clinical analysis established OPA1^High tumors as having elevated growth rates, consolidating mitochondrial hyperfusion as a prognostic determinant. Therapeutically, MYLS22-a first-in-class OPA1 inhibitor-suppressed mitochondrial hyperfusion and reduced stemness in patient-derived organoids. The present work unveils an OPA1-mediated mitochondrial fusion-YAP1 nuclear translocation axis as the cornerstone of AM stemness, proposing OPA1 as a druggable target for this recalcitrant tumor.

Renal fibrosis is the main pathologic change observed with the progression of chronic kidney disease (CKD), which predicts kidney outcomes. The ability to detect fibrosis early in the disease course may be crucial to identify those at the highest risk of CKD progression. Clinical studies have observed increased expression of serum matrix Gla protein (MGP), a potent inhibitor of soft tissue calcification, in patients with CKD. In a cross-sectional study of patients with CKD, serum MGP levels were found to be associated with albuminuria and waist circumference after controlling for kidney function, which modified the association between MGP and albuminuria. To examine the impact of MGP on the onset and progression of CKD, various mouse models were used in the current study. Using Cre-reporter, Rosa^Tomato;Mgp-Cre mice and a new knock-in model expressing hemagglutinin epitope-tagged MGP, it was identified that pericytes in healthy kidneys and myofibroblasts in the folic acid (FA)-injured kidneys are the primary sources of MGP production. FA injection in Mgp^-/- mice induced significantly less renal fibrosis in comparison to the control mice because of a reduced number of pericytes and attenuated Notch signaling. In a complementary experiment, restoration of Mgp expression in myofibroblasts in Mgp^-/- mice leads to renal fibrosis as severe as in control mice. This work suggests that MGP expression in myofibroblasts exacerbates renal fibrosis in FA-injured kidneys.

Ischemic acute kidney injury may accelerate the progression to end-stage renal disease. Megalin has been shown to shuttle stanniocalcin (STC)-1 (which promotes mitochondrial antioxidant defenses) to the mitochondria through the retrograde-early endosomes-to-Golgi pathway; knockout of megalin in cultured cells has been reported to impair glycolysis and mitochondrial respiration. This study sought to determine kidney phenotype after ischemia/reperfusion kidney injury in mice with tubular epithelium-specific deletion of megalin. Mice (on C57B/6 background) with conditional tubular epithelium-specific knockout of megalin (tLrp2KO) and mice with combined conditional tubular epithelium-specific knockout of megalin and overexpression of STC1 (tLrp2KO;tSTC1O) were subjected to ischemia (clamping of renal pedicles), followed by reperfusion for 1, 3, 10, 45, and 90 days. Serum creatinine was measured and kidneys were harvested for analysis. After ischemia/reperfusion (I/R) and compared with control mice, tLrp2KO mice displayed worse acute kidney injury, severe and persistent inflammation, diminished tubular epithelial cell proliferation, up-regulation of TGFβ1 signaling, fibrosis, and accelerated progression to chronic kidney disease. Kidney injury was not rescued in tLrp2KO;tSTC1O mice, consistent with megalin-dependent renal protection by STC1. Freshly isolated proximal tubule fragments from tLrp2KO mice or cultured proximal tubule epithelial cells with megalin knockout displayed activation of TGFβ1 signaling, consistent with modulation of TGFβ1 signaling by megalin. In conclusion, tubular epithelium-specific deletion of megalin aggravates ischemia/reperfusion kidney injury, up-regulates TGFβ1 signaling, and accelerates chronic kidney disease progression.

Stimulator of interferon genes (STING), an effector protein anchored in the endoplasmic reticulum, translocates to Golgi upon activation. Canonically recognized for its central function in innate immune defense against cytosolic endogenous or exogenous double-stranded DNA from damaged host cells or pathogens, STING is now known to have noncanonical functions beyond innate immune surveillance. These novel noncanonical functions of STING include modulating autophagy, maintaining endoplasmic reticulum and mitochondrial calcium homeostasis, interacting with endoplasmic reticulum stress sensor protein, and regulating Golgi proton efflux and integrity of the secretory pathway. Recent research in murine models has linked aberrant STING activation to kidney disorders, including acute kidney injury, podocytopathies, chronic kidney disease, apolipoprotein L1-mediated kidney disease, autosomal dominant polycystic kidney disease, and autosomal dominant tubulointerstitial kidney disease. This review summarizes the diverse functions of STING in addition to interferon signaling, highlighting its emerging importance in the pathogenesis of kidney disease and underscoring its promise as a drug target.

Hypoxia-inducible factor-1α (HIF-1α) is associated with myopia, but the underlying mechanisms remain unclear. This study investigates the role of HIF-1α in ocular refractive development and its mechanisms. Sprague-Dawley rats were induced with myopia using the form deprivation method, and the expression of HIF-1α was analyzed by Western blot analysis. Oxidative stress levels were assessed by measuring reactive oxygen species, superoxide dismutase, and malondialdehyde. Additionally, the protein expression of GPX4 and xCT was evaluated using Western blot analysis and immunohistochemistry, and extracellular matrix remodeling was assessed by measuring matrix metalloproteinase 2 (MMP2), tissue inhibitor of MMP2 (TIMP2), α-smooth muscle actin (α-SMA), and collagen 1α1 (COL1A1). Results showed that HIF-1α expression was significantly up-regulated in form deprivation-induced myopic rats, with increased levels of oxidative stress and ferroptosis. In fibroblast cells under low oxygen conditions, MMP2 and α-SMA levels increased, whereas TIMP2 and COL1A1 levels decreased. Transfection with sh-HIF-1α lentivirus elevated GPX4 and xCT expression, and HIF-1α knockdown reduced MMP2 and α-SMA expression while increasing TIMP2 and COL1A1 expression. However, erastin restored their levels. Furthermore, DNA methyltransferase 3A suppressed HIF-1α expression by promoting its promoter methylation. In conclusion, hypoxia-induced HIF-1α expression promotes ferroptosis and extracellular matrix remodeling, contributing to the pathogenesis of myopia. DNA methyltransferase 3A may reduce HIF-1α expression through methylation, positioning it as a potential target for myopia therapy.

Glycogen storage disease type IV (GSD IV) is a rare autosomal recessive disorder caused by glycogen branching enzyme (GBE1) deficiency, resulting in the accumulation of insoluble polyglucosan. The Gbe1^ys/ys mouse model, carrying the p.Y329S variant, recapitulates features of adult-onset GSD IV, also known as adult polyglucosan body disease. However, the natural progression of the disease in this model is not fully understood. This study presents a longitudinal analysis of Gbe1^ys/ys mice from 1 to 12 months of age, quantitatively tracking polyglucosan accumulation and correlating it with progressive histopathologic, motor, and behavioral changes. Polyglucosan bodies were detected as early as 1 month, with significant neurodegeneration and astrogliosis by 6 months. Notably, serum neurofilament light chain levels increased with disease progression, identifying neurofilament light chain as a potential noninvasive biomarker of neurodegeneration in GSD IV. Systemic involvement, including severe splenomegaly and gastrointestinal abnormalities, indicates broader effects of GBE1 deficiency beyond the central nervous system. These findings provide important insights into the natural history of GSD IV, establish key disease milestones for therapeutic intervention, and refine the clinical understanding of GSD IV and adult polyglucosan body disease.

Glucocorticoids (GCs) are widely prescribed anti-inflammatory agents. Unfortunately, many people experience negative adverse effects associated with long term GC therapy, developing GC-induced ocular hypertension (GC-OHT), which can lead to secondary glaucoma. Approximately 40% of the treated individuals are susceptible to GC-OHT. Seventy years since this discovery, the molecular mechanisms underlying GC-OHT remain unclear. We previously developed a mouse model of GC-OHT delivering the potent GC dexamethasone and observed strain-specific disparities in the development of GC-OHT. We now compare phenotypic and transcriptomic differences between five genetically distinct inbred mouse strains to identify biomarkers of GC susceptibility, and to better understand the molecular mechanisms of GC-OHT. Like humans, mouse strains differ in their ability to develop GC-OHT. Phenotypic characterization revealed that C57BL/6J and C3H/HeJ mice are GC responders and more susceptible to develop GC-OHT. Dexamethasone treatment in these strains led to elevated intraocular pressure compared with the GC nonresponder strains DBA/2J.Gpnmb⁺, 129P3/J, and BALB/cJ. Transcriptomic analysis of responder and nonresponder mouse strains revealed novel trabecular meshwork biomarkers of GC-OHT susceptibility involving enrichment of molecular pathways unique to this response. The present study identifies putative mechanisms underlying GC-OHT and provides insight into the pathogenesis of the clinically similar but more prevalent primary open-angle glaucoma.