Search Results (866)

Hypertensive nephropathy (HN) is a leading cause of chronic kidney disease and end-stage renal disease worldwide and results from the long-term effects of hypertension on renal structure and function. The pathogenesis of HN is complex and involves haemodynamic disturbances, renal vascular injury, oxidative stress, chronic inflammation, and progressive interstitial fibrosis. In recent years, increasing attention has focused on the role of non-coding RNAs (ncRNAs)—including microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs)—as key regulators of gene expression involved in these processes. This review summarises the current understanding of the molecular mechanisms underlying HN, with particular emphasis on the roles of oxidative stress, activation of the renin–angiotensin–aldosterone system, transforming growth factor beta signalling, and inflammatory and fibrogenic pathways. The contribution of dysregulated ncRNAs to endothelial dysfunction, inflammatory responses, apoptosis, angiogenesis, and renal remodelling and fibrosis is also discussed. Particular attention is given to miRNAs and lncRNAs as mediators of disease progression and potential biomarkers, as well as to the emerging role of circRNAs in hypertensive kidney injury, including their involvement in the regulation of redox balance and intercellular communication. Collectively, available evidence indicates that ncRNAs represent a critical link between haemodynamic stimuli and persistent molecular alterations in renal tissue, highlighting their potential as diagnostic markers and therapeutic targets in HN. Full article

Background: Ectopic fat deposition has been demonstrated to play a critical role in the onset and progression of renal dysfunction. However, research on renal parenchymal fat deposition and its association with renal dysfunction in type 2 diabetes mellitus (T2DM) remains limited, particularly regarding its association with early kidney injury. The present study aimed to further investigate the relationship between renal fat fraction (FF) and biomarkers of kidney injury, thereby providing new evidence for the potential link between intrarenal fat accumulation and early renal impairment in T2DM. Methods: This cross-sectional study enrolled 60 patients with T2DM. Renal FF was quantitatively assessed using magnetic resonance imaging (MRI). Clinical characteristics, body composition parameters, and biochemical indices were collected. Levels of kidney injury biomarkers, including tumor necrosis factor receptors 1 (TNF-R1), tumor necrosis factor receptors 2 (TNF-R2), chitinase-3-like protein 1 (YKL-40), and kidney injury molecule-1 (KIM-1), were measured using enzyme-linked immunosorbent assay (ELISA). To evaluate the correlations between fat distribution and inflammatory biomarkers, Pearson correlation analysis was performed. Furthermore, linear regression analysis was conducted to explore the associations between renal FF and kidney injury biomarkers with adjustments for potential confounders such as smoking status, diabetes duration, and visceral fat. Lasso regression was used to screen variables. Results: The results demonstrated that renal FF was significantly positively correlated with serum YKL-40 (r = 0.3, p = 0.021), TNF-R1 (r = 0.246, p = 0.042), and urinary KIM-1 (r = 0.396, p = 0.004), indicating a close association between renal fat accumulation and early kidney injury biomarkers. In regression analyses adjusted for age, sex, and duration of diabetes, the associations between renal FF and these biomarkers remained significant. After further adjustment for potential confounders, including smoking history, alcohol consumption, hypertension, renin-angiotensin-aldosterone system (RAAS) inhibitors, sodium-dependent glucose transporters 2 (SGLT2) inhibitors, glucagon-Like Peptide-1 (GLP-1) receptor agonists, and lipid-lowering drugs, renal FF remained significantly associated with TNF-R1 (β = 0.327, p = 0.015), KIM-1 (β = 0.352, p = 0.021), and YKL-40 (β = 0.275, p = 0.025). Moreover, even after additional adjustment for visceral fat, the associations of renal FF with TNF-R1 and KIM-1 persisted. After using the Benjamini–Hochberg procedure for false discovery rate, the relationship between renal FF and KIM-1 had a significant difference. Variables of age and gender were excluded to build the parsimonious modeling using Lasso regression. It suggested that renal fat accumulation may contribute to kidney injury independently of visceral adiposity. Conclusions: The study systematically demonstrates a significant association between renal FF and early biomarkers of kidney injury in T2DM, which may suggest the potential role of renal fat accumulation in the pathogenesis of diabetic nephropathy. These findings provide clinical data support for the development of a fat-targeted intervention study. Future research should further elucidate the long-term mechanistic role of renal FF in diabetic nephropathy, as well as its potential value in early diagnosis and therapeutic applications. Full article

Glucocorticoid-induced hypertension affects over 30% of treated patients, yet its underlying mechanisms remain unclear, particularly how glucocorticoids regulate renin within the renin-angiotensin-aldosterone system (RAAS). Modeling these dynamics is difficult because only four dose-response measurements are available at a single 24-h timepoint (36 observations total), while the system depends on roughly eleven biochemical parameters spanning minutes-long receptor interactions to days-long protein secretion. Classical parameter estimation becomes unreliable in this extremely underdetermined setting, and purely data-driven methods offer limited biological interpretability. In this paper, we introduce a physics-informed neural network (PINN) framework that integrates ELISA measurements from As4.1 juxtaglomerular cells, ordinary differential equations describing glucocorticoid receptor signaling and renin transcription, and automatic differentiation to enforce mechanistic constraints. By systematically tuning synthetic-data weights (SW in {0.2, 0.3, 0.5}), we identify an intermediate value of SW = 0.3 that provides the best overall balance between predictive accuracy, accepted ensemble size, and biologically plausible parameter estimates among the tested configurations. The framework uses adaptive constraint scheduling with a plateau ramp to reduce premature convergence and introduces calibrated plausibility thresholds reflecting experimental noise. The accepted PINN ensemble (n = 5, 50% success rate) achieved R² = 0.803, compared with 0.759 for the SW = 0.5 baseline and −0.220 for the ODE-only baseline, with RMSE = 0.024. Key learned parameters (IC₅₀ = 2.925 ± 0.012 mg/dL, Hill = 1.950 ± 0.009) are biologically plausible within the model assumptions, and the best single accepted model attained R² = 0.891. Information criteria favored the PINN over the ODE model, with improvements of approximately 77× (AIC) and 5.9× (BIC). Despite training on a single timepoint, the PINN also infers full 48-h trajectories and reproduces non-monotonic dose-response behavior. This work presents, to our knowledge, the first PINN framework for glucocorticoid-mediated renin regulation and should be interpreted as a proof-of-concept approach for integrating sparse biomedical data with mechanistic constraints. The inferred parameters and temporal dynamics are best viewed as model-dependent, hypothesis-generating estimates rather than validated biological quantities. Full article

Background/Objectives: The renin–angiotensin–aldosterone (RAA) system is a key regulator of cardiovascular homeostasis. Recent evidence suggests that Angiotensin II (Ang II) can trigger ferroptosis, an iron-dependent form of cell death. We previously demonstrated that periodontitis induces neurovascular dysfunction, and our preliminary observations indicate that this oral inflammatory model is associated with elevated blood pressure. However, the mechanism by which Ang II impaired nitrergic vasodilation and triggered ferroptosis in cerebral arteries remains unclear. This study investigates the functional effects of electrical and chemical nerve stimulation in adult spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY). Methods: Endothelium-denuded basilar arterial (BA) rings from SHRs and WKYs were used to assess the impact of Ang II on neurogenic relaxation via wire myography. Results: Vascular relaxation responses to nicotine and transmural nerve stimulation (TNS) were significantly diminished in SHRs compared to WKYs. This impairment was reversed by both acute preincubation and chronic treatment with losartan (an AT1 receptor antagonist). In WKY BAs, exogenous Ang II pretreatment inhibited relaxation responses to nicotine, TNS, and isoproterenol. Importantly, this inhibition was effectively reversed by marimastat (MMP inhibitor), catalase (antioxidant), and ferrostatin-1 (ferroptosis inhibitor). Conclusions: Our findings indicate that Ang II induces functional alterations in neurovascular signaling patterns by triggering ferroptosis within nerve terminals. This process leads to a functional imbalance between sympathetic and parasympathetic influences, ultimately impairing neurogenic nitrergic dilation in the BAs of SHRs. These results suggest that targeting Ang II-induced ferroptosis may alleviate the neuroinflammation and cognitive decline associated with hypertension-related cerebrovascular dysfunction. Full article

Endocrine disorders are increasingly recognized as major contributors to secondary cardiomyopathies, leading to profound alterations in cardiac structure and function. This comprehensive review synthesizes current evidence on the genetic basis of cardiomyopathies associated with endocrine conditions, including primary aldosteronism, Cushing’s syndrome, pheochromocytoma/paraganglioma, acromegaly, thyroid disorders, hyperparathyroidism, and diabetic cardiomyopathy. We examine the contribution of somatic and germline mutations, genetic polymorphisms, shared molecular pathways transforming growth factor-β (TGF-β)/SMAD (TGF-β/SMAD signaling, the renin–angiotensin–aldosterone system, oxidative stress, and calcium handling), sarcomeric gene modifiers, ion channel variants, and epigenetic mechanisms to disease pathogenesis. We propose a conceptual framework distinguishing three major categories of genetic involvement: (i) variants causing the primary endocrinopathy; (ii) genetic modifiers of myocardial susceptibility under conditions of hormonal excess; and (iii) direct pleiotropic effects, whereby single gene variants independently cause both endocrine and cardiac phenotypes. In addition, we discuss genotype–phenotype correlations, ethnic and population differences in genetic susceptibility, the emerging role of polygenic risk scores, and precision medicine approaches. Overall, this review provides an integrated perspective on the complex genetic architecture of endocrine-related cardiomyopathies and outlines practical considerations for genetic testing aimed at improving patient management and clinical outcomes. Full article

Background: The prognostic value of discharge renin–angiotensin–aldosterone system inhibitor (RASi) therapy in contemporary PCI-treated acute myocardial infarction (AMI) survivors with preserved or mildly reduced left ventricular ejection fraction (LVEF) remains uncertain. Methods: A retrospective cohort study of 2530 AMI patients (2019–2022) stratified by RASi use. Exclusion criteria were in-hospital mortality, LVEF < 40%, contraindications to the use of RASis or no percutaneous coronary intervention (PCI). Primary endpoints included heart failure (HF) events, recurrent acute coronary syndrome (ACS), and all-cause mortality. Kaplan–Meier analyses and inverse probability of treatment weighting (IPTW)-weighted Cox models were applied. Results: Over a mean follow-up of 49 months, discharge RASi therapy was not associated with all-cause mortality overall, but was associated with fewer HF rehospitalizations (HR 0.62, 95% CI 0.40–0.95; p = 0.03). Mortality associations differed by AMI type and hypertension status, particularly for NSTEMI (HR 0.36, 95% CI 0.14–0.91; p = 0.03; p for interaction = 0.02) and hypertension (HR 0.36, 95% CI 0.15–0.84; p = 0.02; p for interaction = 0.04). Conclusions: In this single-center observational cohort of PCI-treated AMI survivors with LVEF ≥ 40%, discharge RASi therapy was associated with fewer HF rehospitalizations but not with lower overall mortality. Exploratory subgroup analyses suggested potential heterogeneity according to NSTEMI status and hypertension, but these findings should be considered hypothesis-generating and require confirmation. Full article

Background: Secondary pseudohypoaldosteronism (PHA) is a rare, transient condition caused by renal tubular resistance to aldosterone, most commonly associated with urinary tract infection (UTI) and/or congenital anomalies of the kidney and urinary tract (CAKUT). It mimics primary adrenal disorders, presenting with life-threatening electrolyte disturbances in early infancy. Case Presentation: We report a male infant admitted twice within the first four months of life with severe dehydration, hyponatremia, hyperkalemia, metabolic acidosis, and acute kidney injury (AKI). Urine cultures grew Klebsiella pneumoniae and later Escherichia coli. Imaging studies demonstrated obstructive CAKUT, including posterior urethral valves, bilateral megaureters, hydronephrosis, and bladder diverticulosis. Congenital adrenal hyperplasia was excluded. Further evaluation showed markedly elevated plasma renin and aldosterone levels, confirming secondary PHA. The patient was successfully treated with intravenous fluids, electrolyte correction, and antibiotic therapy. Subsequently, oral sodium chloride and bicarbonate supplementation were added. Stepwise surgical correction of the urinary tract anomalies was initiated. Conclusions: Secondary PHA should be considered in infants presenting with failure to thrive, dehydration, hyponatremia, and hyperkalemia, particularly in the presence of UTI or CAKUT. Early recognition and differentiation from primary adrenal disorders are essential to prevent life-threatening complications. Prompt correction of electrolyte imbalance and management of the underlying urinary tract pathology are crucial for favorable outcomes. Full article

The perception that hormonal contraception causes weight gain is a general belief that frequently hinders the initiation and continuation of effective family planning. This narrative review analyses data from Cochrane systematic reviews and recent pharmacogenomic studies to separate patient perception from metabolic reality. Analysis of high-quality data, including Cochrane systematic reviews, indicates that the association between Combined Hormonal Contraceptives (CHCs)—including oral pills, the transdermal patch, and the vaginal ring—and weight gain is not supported by consistent high-quality evidence. Placebo-controlled trials demonstrate that these methods are weight-neutral on average. Perceived weight increases in CHC users are likely mediated in part by fluid retention linked to the estrogenic stimulation of the Renin–Angiotensin–Aldosterone System (RAAS), rather than adipose tissue accumulation. Conversely, Depot Medroxyprogesterone Acetate (DMPA) represents a verified clinical risk for weight gain, showing a demonstrated clinical association with significant fat mass accumulation. Hypothesized biological mechanisms for this increase include hypothalamic appetite stimulation and glucocorticoid-like activity. The etonogestrel implant occupies a complex middle ground. While population-level data suggests weight neutrality, recent exploratory pharmacogenomic research has identified a specific variant in the Estrogen Receptor 1 (ESR1) gene. For the minority of women carrying this variant, the implant may trigger clinically significant weight gain, suggesting a biological basis for their subjective experience despite statistical evidence. Ultimately, the persistence of the weight gain concern is fueled by the nocebo effect and the misattribution of natural age-related weight trajectories to contraceptive use. Full article

Background: Recent advancements in heart failure (HF) therapy have significantly enhanced the management of patients across all phenotypes of left ventricular ejection fraction. However, these multidrug regimens frequently induce alterations in renal function by influencing intrarenal hemodynamics, thereby modifying glomerular capillary pressure. This phenomenon could result in a mild to moderate decline in estimated glomerular filtration rate (eGFR), often classified as “worsening kidney function.” This nomenclature stems from consistent observations of eGFR reductions recorded during HF treatment in clinical trials. This narrative review aims to elucidate why the observed eGFR declines in clinical practice may represent either loss of functioning glomeruli or pharmacologically mediated reductions in intraglomerular pressure that ultimately safeguards long-term renal and cardiovascular outcomes. Methods: By a comprehensive re-examination of data from HF clinical trials conducted with various classes of medications, all affecting eGFR, we sought to provide evidence that the decline in eGFR is associated with the activation of specific mechanisms that collectively contribute to a reduction in glomerular filtration pressure, a prominent factor in maladaptive neurohormonal responses. Results: From the investigation of angiotensin-converting enzyme inhibitors to the more recent non-steroidal mineralocorticoid receptor antagonist, the renal effects of these therapeutic regimens correlate with improvements in patient outcomes. The data consistently indicate that an early decline in eGFR, when coupled with an enhancement in HF outcomes, is associated with a more gradual decline in eGFR during long-term follow-up. Conclusions: Clinicians should recognize early declines in eGFR as indicators of favorable intraglomerular hemodynamic adjustments that mitigate maladaptive neurohormonal responses and contribute to improved long-term outcomes in patients with HF. Full article

Background: Vascular compression syndromes are increasingly recognized as underdiagnosed contributors to morbidity in patients exhibiting dysautonomia. Underlying vascular compression syndromes affecting the head and neck, abdomen, pelvis, and lower extremities may influence venous return, neurohormonal signaling, and autonomic regulation. There is considerable clinical overlap among these syndromes, as well as between hypermobility spectrum disorders (HSD) and dysautonomia, indicating possible shared or interacting pathophysiological mechanisms. Purpose/Aims: This hypothesis-generating narrative review synthesizes current evidence linking vascular compression syndromes with dysautonomia, highlights potential mechanistic pathways, identifies patterns of syndromic overlap, and emphasizes the importance of systematic evaluation in affected patient populations. Key Findings: Evidence from retrospective studies, case series, and clinical observations indicates that vascular compression syndromes may be prevalent among patients with dysautonomia, particularly postural orthostatic tachycardia syndrome (POTS) and HSD, yet are often unrecognized. Proposed mechanisms based on limited data include impaired venous capacitance and preload reserve, increased intracranial pressure, altered renin–aldosterone and cortisol signaling, underlying autoimmune and systemic diseases, and sympathetic ganglion irritation. Several compression syndromes show symptom overlap and frequent co-occurrence, especially in patients with connective tissue disorders. Emerging data suggest that targeted interventions, such as surgical decompression or venous stenting, may improve orthostatic intolerance and quality-of-life measures in selected patients, though high-quality prospective data remain limited. Conclusions: Vascular compression syndromes may be an important yet underappreciated contributor to dysautonomia. Increased clinical awareness and systematic screening may reduce diagnostic delays and morbidity in this underserved population. Prospective studies are needed to clarify prevalence, establish causal relationships, and determine the impact of targeted treatments on autonomic outcomes. Full article

Background: Obstructive sleep apnea (OSA) is associated with lower urinary tract symptoms (LUTS), particularly nocturia, though mechanisms including hypoxia, intrathoracic pressure changes, and hormonal alterations. While age and severity may influence these associations, stratified analyses remain limited. This study examined polysomnographic (PSG) parameters, International Prostate Symptom Score (IPSS) components, and hormonal/electrolyte markers in age- and severity-stratified men with suspected OSA. Methods: In this cross-sectional study, 104 men (mean age 60.8 ± 9.8 years) underwent PSG. Analyses were stratified by age (<60 vs. ≥60 years) and respiratory disturbance index (RDI) severity. Correlations were used to assess PSG indices, IPSS subdomains (irritative, obstructive, quality of life [QoL]), and markers including antidiuretic hormone [ADH], aldosterone, plasma renin activity [PRA], sodium, potassium. Nocturnal polyuria index (NPI ≥ 33%) was calculated in a subset of participants. Pearson correlations, ANOVA, and Kruskal–Wallis tests were used (p < 0.05), with adjustments for multiple comparisons. Results: Moderate OSA predominated (RDI 27.2 ± 20.4 events/h); nocturia affected 61.5% of the cohort. In those <60 years (n = 48), mild RDI correlated with nocturia (r = 0.42, p = 0.028), while severe RDI correlated strongly with the obstructive subscore (r = 0.96, p = 0.009). In those ≥60 years (n = 56), QoL correlated with sleep efficiency (r = 0.48, p = 0.012) and total sleep time (r = 0.46, p = 0.015). Severe RDI was associated with higher IPSS (14.5 ± 6.2 vs. 10.5 ± 4.8, p = 0.028) and nocturia (3.5 ± 1.7 vs. 2.4 ± 1.1, p = 0.02). ADH was significantly lower in severe OSA (1.4 ± 0.8 vs. 2.7 ± 1.1 pg/mL, p = 0.03). Conclusions: Age and OSA severity modulate PSG–LUTS–hormonal associations. Younger men exhibit hypoxia-linked obstructive symptoms, whereas older men experience sleep fragmentation that impacts QoL. ADH suppression is associated with severe OSA. Full article

Heart failure with preserved ejection fraction (HFpEF) represents the predominant form of heart failure, affecting over 50% of all heart failure patients with increasing prevalence in aging populations. Despite significant advances in cardiovascular medicine, HFpEF remains a complex clinical syndrome with poorly understood pathophysiology and limited treatment options. While most studies have traditionally focused on the renin–angiotensin–aldosterone system (RAAS) and other related mechanisms, emerging evidence has unveiled a critical bidirectional relationship between dysregulation of gut microbiota and HFpEF development. This phenomenon, mediated through microbiome-driven inflammation and endothelial dysfunction, introduces a novel concept and potential emerging conceptual framework in understanding HFpEF. This comprehensive review explores this novel gut–heart axis by synthesizing the latest evidence from original studies and clinical trials. We discuss novel mechanisms involving bacterial metabolites, including short-chain fatty acids (SCFAs), trimethylamine N-oxide (TMAO), bile acids, and amino acid derivatives. We also examine how gut dysbiosis may contribute to systemic inflammation through lipopolysaccharide translocation, NLRP3 inflammasome activation, and endothelial dysfunction. Furthermore, clinical trials investigating microbiome-targeted interventions, including probiotics, fecal microbiota transplantation, metabolite supplementation, and precision medicine approaches, are critically evaluated for their therapeutic potential. This review provides a framework for hypothesis generation and future research directions about therapeutic strategies targeting the gut–heart axis in HFpEF management. Full article

Hypertension-induced renal injury is a major cause of chronic kidney disease and end-stage renal disease. Increasing evidence indicates that disease progression is not driven solely by hemodynamic stress but results from the interplay of multiple molecular mechanisms. In this review, we propose a stage-structured and network-based framework to systematically integrate current mechanistic insights into hypertension-induced renal injury. Early events, mainly including endothelial dysfunction and renal hypoxia, establish a permissive microenvironment for disease progression. These insults activate amplifying pathways such as the renin–angiotensin–aldosterone system (RAAS) overactivation, oxidative stress, immune and inflammatory responses, and sympathetic nervous system hyperactivity, which interact through cross-talk and positive feedback loops. Ultimately, these signals converge on fibrotic programs characterized by epithelial–mesenchymal transition (EMT), fibroblast activation, and extracellular matrix deposition, leading to irreversible structural remodeling and functional decline. Furthermore, epigenetics, the gut–kidney axis, autophagy dysfunction and renal aging also contribute to this process. We highlight two critical and underappreciated aspects: the existence of a permissive ‘early-window’ dominated by endothelial dysfunction and hypoxia, which sets the stage for later amplification; and the hierarchical interplay between amplifying mechanisms where cross talk creates self-reinforcing loops that may explain therapeutic resistance. In addition, this review highlights emerging biomarkers for early diagnosis and disease monitoring, and discusses therapeutic advances that extend beyond blood pressure control to disease-modifying interventions that confer renoprotective effects. By integrating molecular mechanisms with diagnostic and therapeutic perspectives, this review provides a comprehensive framework for early detection and precision intervention in hypertension-induced renal injury. Full article

Diabetic kidney disease (DKD) is a major complication of diabetes mellitus that contributes substantially to chronic kidney failure and increased cardiovascular risk. Beyond progressive deterioration of renal function, DKD is associated with disturbances in endocrine and vascular regulation. Among these, alterations in vitamin D homeostasis and blood pressure (BP) control represent clinically relevant, yet incompletely integrated aspects of DKD pathophysiology. This narrative review synthesizes current evidence on the multidirectional relationships between DKD, vitamin D deficiency, and arterial hypertension (AH). Attention is given to renal mechanisms responsible for reduced vitamin D availability in DKD, including proteinuria-related loss of vitamin D-binding proteins, impaired proximal tubular reabsorption, decreased renal activation of vitamin D, and hormonal regulators such as fibroblast growth factor-23. It further discusses how insufficient vitamin D signaling may influence renal and vascular pathways involved in BP regulation. Mechanistic links between vitamin D deficiency and AH in DKD are discussed, with emphasis on maladaptive activation of the renin–angiotensin–aldosterone system (RAAS), persistent inflammation, oxidative stress, endothelial dysfunction, and insulin resistance. These interdependent processes promote both renal injury progression and sustained elevations in BP, forming a self-reinforcing pathogenic loop. Finally, available data on vitamin D-based therapeutic strategies in DKD are reviewed, including native vitamin D supplementation, active vitamin D metabolites, and vitamin D receptor agonists. Although experimental and observational studies suggest potential nephroprotective and vasculoprotective effects, evidence from randomized clinical trials remains heterogeneous. Further well-designed prospective studies are required to clarify the clinical utility of vitamin D interventions in patients with DKD and coexisting AH. Full article

Cardiac fibrosis represents a final common pathway in a wide range of cardiac disorders, leading to structural remodeling, diastolic dysfunction, and heart failure. From a pathologist’s viewpoint, fibrotic remodeling displays distinctive morphologic patterns such as interstitial, perivascular, and replacement fibrosis, which mirror specific cellular and molecular mechanisms. Central to this process is the activation of cardiac fibroblasts into myofibroblasts, driven by profibrotic signaling cascades such as transforming growth factor beta (TGF-β)/mothers against decapentaplegic homolog proteins (SMAD), Wingless/Integrated signaling pathway (Wnt)/βeta-catenin, and Hippo-Yes-associated protein (YAP)/transcriptional coactivator with PDZ-binding motif (TAZ) pathways. Neurohumoral mediators, including angiotensin II and aldosterone, further amplify extracellular matrix synthesis and tissue stiffness. Epigenetic modulators and non-coding RNAs (n-c RNAs) orchestrate transcriptional programs that perpetuate fibroblast activation. Histopathological correlates of these molecular events, collagen deposition, alpha-smooth muscle actin (α-SMA) expression, and extracellular matrix (ECM) cross-linking, can be demonstrated through immunohistochemistry and digital morphometry. This review integrates molecular signaling and morphologic evidence to delineate the mechanisms of cardiac fibrosis, emphasizing the pathologist’s role as a link between molecular insight and diagnostic interpretation. Understanding these intertwined processes provides the foundation for novel antifibrotic therapies targeting key molecular nodes of fibroblast activation and matrix remodeling. Full article