Search Results (734)

Excitotoxicity is one of the factors that participates in neurodegeneration, impairing neuronal and glial cells’ function, and leading to the development of chronic neurodegenerative diseases. The main mechanism of action lies in the overstimulation of excitatory receptors, especially the NMDA (N-methyl-D-aspartic acid) receptor, by glutamate, which promotes a massive influx of Ca²⁺ that is not sufficiently buffered by the intracellular machinery, or not released by mechanisms such as Ca²⁺ ATPase and plasma membrane Ca²⁺/Na⁺ exchanger promoting, among other toxic effects, mitochondrial damage and an increase in reactive oxygen species (ROS). Notably, many cases reported of long COVID-19 describe significant brain alterations and neuropsychiatric disorders, including delirium, depression, etc., and patients required increased use of antidepressant or anxiolytic drugs, for example. In addition, emerging evidence links neurodegeneration as a potential long-term sequelae associated with an increased number of patients with cognitive disorders. This review analyzes data from the literature regarding brain alterations associated with post-COVID-19 syndrome and explores a potential link to the excitotoxicity pathways, due to its participation in neurodegeneration by homeostatic failure, and it is clearly present in various brain conditions, such as Alzheimer’s and Parkinson’s diseases. Full article

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and long Coronavirus Disease 2019 (long COVID) are complex chronic conditions that often follow infectious triggers with overlapping clinical features but poorly defined pathophysiological relationships. This study aimed to identify disease-specific immune signatures through multiparameter immunophenotyping of monocytes, dendritic cells, and T cell subsets. A total of 207 participants were included (ME/CFS: n = 103; long COVID: n = 63; healthy controls: n = 41). Peripheral blood mononuclear cells were analyzed using multiparameter flow cytometry. Statistical analyses included non-parametric testing, age-adjusted Analysis of covariance (ANCOVA), correlation network analysis, and principal component analysis (PCA). Long COVID was characterized by increased M2-like monocyte polarization, elevated CD80 expression across monocyte subsets, expansion of dendritic cells, and reduced expression of activation markers, indicating persistent immune activation with features of immune exhaustion. In contrast, ME/CFS exhibited reduced costimulatory molecule expression, impaired C-C chemokine receptor type 7 (CCR7)-mediated immune cell trafficking, and less coordinated activation patterns, consistent with a state of immune suppression. Correlation network analysis revealed more extensive and integrated immune interactions in long COVID, while PCA identified distinct immunophenotypic components and enabled moderate discrimination between the two conditions. These findings demonstrate that ME/CFS and long COVID are characterized by distinct immune profiles, supporting the concept of divergent immunopathological mechanisms. The identified signatures may contribute to biomarker development and guide targeted therapeutic approaches. Full article

Supplemental oxygen is a cornerstone intervention in modern clinical practice, widely used to correct hypoxemia in emergency, perioperative, and critical care settings. While oxygen therapy is lifesaving, accumulating evidence indicates that excessive oxygen exposure can induce significant pathophysiological disturbances, particularly within the cardiovascular and pulmonary systems. Hyperoxia (PaO₂ > 100 mm Hg) promotes the generation of reactive oxygen species (ROS), leading to oxidative stress, mitochondrial dysfunction, and the activation of pro-fibrotic pathways. When combined with mechanical ventilation, these effects are further amplified through alterations in intrathoracic pressure, reduced venous return, and increased pulmonary vascular resistance, collectively imposing hemodynamic stress on the myocardium. These mechanical and biochemical perturbations converge to drive structural, functional, and electrical remodeling of the heart, including conduction abnormalities and arrhythmogenesis. Emerging clinical insights, particularly from critically ill and COVID-19 populations, underscore the importance of titrated oxygen strategies that balance adequate tissue oxygenation with minimization of hyperoxic injury. This review synthesizes current evidence on hyperoxia-induced oxidative stress, heart-lung interactions, and mechanisms underlying myocardial remodeling to provide a comprehensive framework for optimizing oxygen therapy. Full article

Background. Despite technological innovations and improvements in stents and devices, sex-related discrepancies are still reported in the outcomes after ST-segment elevation myocardial infarction (STEMI), depending on biological and sex-specific pathophysiological differences, which have not been completely understood. The aim of the present study was to provide real-world data on the prognostic role of sex among patients with STEMI, enclosed into a recent up-to-date international registry. Methods. The ISACS-STEMI COVID-19 is a large-scale retrospective registry, including STEMI patients treated with mechanical reperfusion between 1 March and 30 June, 2019 and 2020. Patients, treated in 109 centers across Europe, Latin America, Southeast Asia, and North Africa, were grouped according to sex. Primary endpoint: In-hospital mortality; secondary endpoints: Time delay, 30-day mortality, and postprocedural Thrombolysis In Myocardial Infarction (TIMI) 3 flow. Results. We included 16,083 patients, 24.3% females (54.3% hospitalized in 2019, 45.7% in 2020). Women with STEMI were older, more often diabetic and hypertensive (p < 0.001), with a higher prevalence of hypercholesterolemia (p = 0.02), longer ischemia time (p = 0.01), ambulance referral (p = 0.03) and cardiogenic shock at presentation (p = 0.05), but less frequently smokers, with a previous cardiovascular event (p < 0.001) or anterior STEMI (p = 0.03) as compared to males. Preprocedural TIMI 0 flow, multivessel disease, need for thrombectomy (p < 0.001 and p = 0.001, respectively), use of Glycoprotein IIbIIIa inhibitors or cangrelor, radial access and implantation of drug-eluting stents (p < 0.001, p < 0.001 and p = 0.001, respectively) were also more common in men. Impaired postprocedural epicardial reperfusion (TIMI flow 0–2) was observed more frequently in females as compared to males (10% vs. 7.2%; adjusted OR [95% CI] = 1.30 [1.13–1.49], p = 0.01). In-hospital mortality was 5.8%, significantly higher among women (8.3% vs. 5%, p < 0.001, adjusted HR [95% CI] = 1.26 [1.06–1.5], p = 0.01). Similar data were observed for 30-day mortality (10.3% vs. 6.2%, p < 0.001, adjusted HR [95% CI] = 1.22 [1.06–1.38], p = 0.007). Conclusions. Among STEMI patients being treated with the most updated standard of care for primary percutaneous coronary intervention, female sex is still associated with higher complexity and impaired prognosis, displaying suboptimal epicardial reperfusion and increased in-hospital and 30-day mortality. Full article

Coronavirus Disease 2019 (COVID-19) and other lower respiratory tract diseases (LRTDs), including bacterial pneumonia and acute respiratory distress syndrome, share overlapping clinical features but arise from distinct pathophysiological mechanisms. The molecular signatures that distinguish these diseases remain insufficiently characterized in African populations, where genetic background, endemic infections, and environmental exposures may substantially shape immune responses. We integrated spatially resolved single-cell transcriptomic profiles from lung autopsy specimens of 30 Malawian patients, including 10 with COVID-19, 12 with other LRTDs, and 8 non-LRTD controls. In total, 61,391 cells representing 15 cell types and 36,602 gene expression features were analyzed. Using an integrated machine learning framework that combined nine feature-ranking algorithms with incremental feature selection, we identified potential molecular signatures that could discriminate among disease states within this cohort. The optimal classification models achieved weighted F1 scores greater than 0.94, demonstrating a robust capacity to differentiate COVID-19 from other LRTDs in our dataset. Notably, the macrophage-associated state in COVID-19 was dominated by an IFN-γ response with upregulation of CD163 and HLA-DQA2, contrasting sharply with the type I/III interferon signature reported in European cohorts. In addition, we observed cell-type-specific COVID-19 signatures, including downregulation of CAV1 in AT1 cells, consistent with epithelial damage; dysregulation of SFTPC in AT2 cells, suggesting surfactant dysfunction; and upregulation of NFKBIA in neutrophils, indicating altered inflammatory regulation. Gene Ontology enrichment further revealed universal disruption of protein synthesis machinery, along with cell-type-specific alterations in immune activation, epithelial repair, and inflammatory signaling pathways. Full article

Background: One of the most debated scientific topics in recent years is the role of non-invasive respiratory support techniques in the treatment of de novo acute hypoxemic respiratory failure. Until pre-COVID-19, the most accredited guidelines did not make recommendations for or against the use of these techniques in this clinical condition, and the increased risk of adverse events for patients who failed the non-invasive approach was widely reported in the literature. The most recent guidelines recommend the use of HFNC as a first-line technique in the treatment of de novo acute hypoxemic respiratory failure to avoid the need for tracheal intubation. However, the strength of these recommendations remains weak, the quality of the underlying evidence is poor, and their usefulness in deciding which technique to apply to an individual patient is questionable. Aim: The aim of this review was to provide the reader with some critical tools to interpret the different indications regarding the choice of the best non-invasive support technique to be used in this setting. Methods: To this end, we analyzed the available literature on this topic, privileging the works that are most useful in correlating the practical indications to the pathophysiological assumptions. Results and Conclusions: The notable heterogeneity of the studies on which the current recommendations are based, as well as the affirmation of the concept of patient self-induced lung injury (P-SILI), highlights the importance of assessing each patient’s risk of developing this complication, individualizing treatment to the patient’s specific needs, and monitoring the patient during treatment. Full article

The disproportionately severe disease course of diabetic patients with SARS-CoV-2 infection was repeatedly observed by clinicians during the COVID-19 pandemic. The overlap between metabolic impairment, viral pathophysiology, and chronic inflammation created a pattern that urged deeper examination. The aim of this paper was to review and synthesize evidence regarding the interaction between diabetes mellitus and COVID-19. We synthesized evidence across mechanistic pathways (immune dysregulation, chronic inflammation, ACE2/DPP-4-related signaling, endothelial dysfunction, and pancreatic involvement) and key clinical outcomes (severity, intensive care unit (ICU) admission, mortality, dysglycaemia/new-onset diabetes, and DKA). This systematic search was conducted in PubMed, Clinical Key, and Google Scholar. The eligibility criteria included papers on adults (≥18 years) with pre-existing diabetes mellitus (type 1 or type 2) or newly diagnosed diabetes/hyperglycemia and confirmed SARS-CoV-2 infection, published between January 2020 and October 2025, in English language. The PRISMA guidelines were used for data extraction. We identified 412 articles, out of which only 30 met all the inclusion criteria. Diabetes was consistently evoked as a major risk factor for severe COVID-19, being associated with higher susceptibility to pneumonia, respiratory failure, ICU admission, and mortality. The explanation lies in the impaired immune system, endothelial dysfunction, and metabolic repercussions imposed by hyperglycemia. Several antidiabetic drugs appeared protective in multiple cohorts. In conclusion, the accumulated evidence underscores the tight interplay between metabolic disease and COVID-19. Essentially, the clinical management of these patients would be a thoughtful selection of antidiabetic therapy and close metabolic monitoring. Full article

Objective: The COVID-19 pandemic has strained healthcare systems and has been associated with substantial morbidity and mortality. Severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2) enters host cells by binding to angiotensin-converting enzyme 2 (ACE2), implicating dysregulation of the renin–angiotensin system (RAS) in COVID-19 pathophysiology. Measurement of circulating RAS components, including ACE and ACE2, may therefore provide an insight into disease severity and underlying mechanisms. Subjects and Methods: In this retrospective cohort study, 224 adults with PCR-confirmed COVID-19 were stratified by World Health Organization disease-severity criteria into asymptomatic, mild, mild-pneumonia, severe, and critical groups. Plasma ACE and ACE2 concentrations were quantified by ELISA. Demographic, clinical, and laboratory data were extracted from electronic medical records. Results and Conclusions: Increasing disease severity was associated with higher mortality, elevated body mass index, and higher viral load estimates. Severe and critical illness was characterized by leukocytosis with neutrophilia, marked lymphopenia, anemia, elevated inflammatory and coagulation markers, renal dysfunction, and hypoalbuminemia. Plasma ACE2 levels declined progressively with increasing severity and were significantly lower in patients with mild-pneumonia, severe, or critical illness compared with asymptomatic or mild cases, showing a strong inverse correlation with severity. In contrast, plasma ACE levels increased significantly with disease severity. The resulting increase in the ACE/ACE2 ratio indicates a progressive shift toward the pro-inflammatory arm of the RAS, providing mechanistic insight into the COVID-19 pathophysiology. Full article

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a chronic, multisystemic disorder characterized by severe, persistent fatigue not alleviated by rest and worsened by minimal exertion, often accompanied by post-exertional malaise (PEM), unrefreshing sleep, cognitive dysfunction, and autonomic disturbances. Despite decades of research, its pathophysiology remains incompletely understood, and skeletal muscle involvement has only recently gained attention. This review aims to provide a historical and pathophysiological synthesis of ME/CFS, emphasizing the pivotal role of skeletal muscle in the onset and persistence of symptoms, and to integrate molecular, cellular, and pathophysiological evidence into a coherent explanatory framework. This is a narrative review of published literature (1990–2025) with critical integration of clinical, biochemical, and experimental data on oxidative stress, mitochondrial dysfunction, Excitation–Contraction (E-C coupling) dysregulation, and muscle secretome alterations in ME/CFS also in relation to post-viral syndromes (e.g., Long COVID). Evidence consistently points to mitochondrial oxidative stress, redox imbalance, impaired Ca²⁺ handling, and altered signaling pathways in skeletal muscle of patients with ME/CFS. Historical milestones show an evolution from psychogenic interpretations toward recognition of ME/CFS as a biological disorder with neuromuscular and metabolic underpinnings. ME/CFS can be interpreted as a skeletal muscle–metabolic disorder characterized by oxidative distress, mitochondrial dysfunction, and impaired energy regulation, leading to the clinical picture of exercise intolerance and post-exertional malaise. Integrating basic and clinical research through a translational approach provides the foundation for new diagnostic tools, targeted therapies, and biomarkers. Full article

Background and Objectives: Osteonecrosis of the jaw (ONJ) occurring after infection with SARS-CoV-2 has emerged as an increasingly reported complication in the post-COVID-19 era. Post-COVID-19 osteonecrosis of the jaw (PC-ONJ) has been described in association with both COVID-19-associated mucormycosis (CAM) and non-fungal phenotypes. This narrative review aims to synthesize and critically analyze the available evidence regarding terminology and classification, epidemiology and risk factors, pathophysiological mechanisms, clinical and imaging characteristics, diagnostic challenges, and management strategies relevant to oral and maxillofacial surgery practice. Materials and Methods: An extensive literature search was conducted in the PubMed/MEDLINE, Scopus, Web of Science, ScienceDirect, and Google Scholar databases. The search targeted peer-reviewed publications published between 2020 and 2025, reflecting the post-pandemic emergence of this clinical spectrum. Original studies, systematic and narrative reviews, multicenter case series, consensus guidelines, and well-documented case reports were considered. Results: Available data, largely derived from case reports and small series, demonstrate a predominance of maxillary involvement and frequent association with diabetes mellitus and systemic corticosteroid therapy. Proposed mechanisms include COVID-19-associated endothelial dysfunction, microvascular thrombosis, immune dysregulation, metabolic imbalance, and treatment-related effects. Clinically, patients may present with persistent orofacial pain, tooth mobility, exposed or probeable bone, and frequent sinonasal extension, with symptoms sometimes preceding bone exposure. Diagnostic challenges arise from the overlap with medication-related osteonecrosis of the jaw (MRONJ), osteoradionecrosis (ORN), and chronic osteomyelitis. Imaging is essential for assessing disease extent but remains insufficient for etiologic differentiation, making histopathological examination and targeted microbiological investigations necessary, particularly to exclude invasive fungal infection. Conclusions: Management must be etiology-driven. CAM requires urgent antifungal therapy combined with surgical debridement, whereas non-fungal forms are generally managed with conservative surgery and appropriate antimicrobial stewardship. Standardized diagnostic criteria and prospective multicenter studies are needed to reduce nosological ambiguity and optimize clinical decision-making in this emerging post-viral condition. Full article

Background: Severe lung compromise from COVID-19, ARDS, and recently AH3N2 can progress to life-threatening hypoxia. Past experience led to standardized protocols that assumed similarity to SARS-CoV. Methods: COVID-19 pathophysiology and histopathological lung biopsy photomicrographs are analyzed. Results: Pneumolysis is defined as progressive alveolar–capillary destruction resulting from SARS-CoV-2 attack on pneumocytes. In the final stages preceding pneumolysis, molecular mechanisms in the lungs include apoptosis in alveolar epithelial type I and II cells, compromising alveolar regeneration, and necrosis, resulting in leakage of intracellular contents and amplifying inflammation. Pyroptosis, driven by inflammasome activity, further disrupts alveolar integrity in ARDS. Histopathological findings include Masson bodies, alveolar-coating cells with nuclear atypia, reactive pneumocytes and reparative fibrosis, intra-alveolar hemorrhage, moderate inflammatory infiltrates and abscesses, microthrombi, hyaline membrane remnants, and emphysema. The three theoretical pathophysiological stages of progressive hypoxemia (silent hypoxemia, gasping, and death zone) are shown. Conclusions: Silent hypoxemia rapidly progresses to critical hypoxemia. This progression results from progressive pneumolysis, inflammation, immune overexpression, autoimmunity, and HAPE-type edema, leading to acute pulmonary insufficiency. Long-lasting COVID-19 can result in fibrosis and, as a compensatory mechanism, polierythrocythemia. The proposed treatment (based on tolerance to hypoxia and the hemoglobin factor) includes prompt oxygen administration, control of inflammatory and immune responses, antibiotics, rehydration, erythropoietin and platelet aggregation inhibitors. Full article

Long COVID is the disease entity triggered and potentially driven by SARS-CoV-2 infection. It is an heterogeneous condition characterized by dozens of different symptoms, signs and sequelae, which can affect all organs and body systems and evolve over the disease course. Clinical manifestations of Long COVID can vary from individual to individual and across the broader patient population. Pathology can range from asymptomatic and subclinical manifestations to fatal outcomes. Over 400 million people worldwide are estimated to suffer, or have suffered, from Long COVID, making the sequelae of SARS-CoV-2 infection one of the greatest public health challenges of the 21st century. This article provides an updated overview of epidemiology, definitions, main concepts and terminology for Long COVID. It also summarizes key evidence of pathology and disease mechanisms in major organs and body systems, such as the immune system, cardiovascular system, endothelium, heart, lungs, central nervous system, peripheral nervous system, gastrointestinal system, hapatobiliary system, pancreas and kidney. Heterogeneity in manifestations, potential risk of death and the degree of disability in several disease subsets call for timely diagnosis of each Long COVID types and a fuller understanding of their pathophysiological underpinnings. Further research is recommended to better understand pathobiology, develop effective clinical trials, and identify treatments and scalable biomarkers. Full article

Background/Objectives: Patients with pre-existing heart failure (HF) represent a clinically vulnerable population with increased susceptibility to adverse outcomes during acute systemic illnesses, including coronavirus disease 2019 (COVID-19). Systemic inflammation is increasingly recognized as a central pathophysiological mechanism linking cardiovascular vulnerability with infection-related organ dysfunction. However, the prognostic role of inflammatory biomarkers in hospitalized COVID-19 patients with pre-existing HF remains incompletely defined. This study aimed to evaluate the association between inflammatory biomarkers and clinical outcomes in this high-risk population. Methods: This retrospective single-center cohort study included 395 consecutive adult patients hospitalized with confirmed COVID-19 between March 2020 and December 2024 at a tertiary referral center. Pre-existing HF was documented in 143 patients (36.2%). Inflammatory biomarkers, including C-reactive protein (CRP), interleukin-6 (IL-6), procalcitonin, and D-dimer, were measured at admission. The primary outcomes were development of sepsis and in-hospital mortality. Multivariable logistic regression models were constructed to identify independent predictors of adverse outcomes after adjustment for demographic characteristics, comorbidities, disease severity, and cardiac biomarkers. Results: Patients with pre-existing HF had significantly higher in-hospital mortality compared with those without HF (11.9% vs. 4.8%, p = 0.016) and showed a trend toward increased intensive care unit admission. HF patients exhibited higher admission IL-6 levels, indicating enhanced inflammatory activation. In univariable analysis, HF was associated with mortality (OR 2.67, 95% CI 1.22–5.83, p = 0.014). After multivariable adjustment, the association between HF and mortality was attenuated, whereas IL-6 remained an independent predictor of mortality (adjusted OR 1.38, 95% CI 1.04–1.82, p = 0.021). Elevated IL-6 and procalcitonin levels were also independently associated with sepsis development. Conclusions: Pre-existing heart failure identifies a population at increased risk of adverse outcomes in hospitalized COVID-19 patients, and this excess risk appears to be partly mediated by systemic inflammatory activation. Interleukin-6 emerged as a key biomarker linking cardiovascular vulnerability, immune dysregulation, and clinical deterioration. These findings support the potential role of inflammation-based risk stratification to improve prognostic assessment and guide personalized management in high-risk patients with underlying cardiovascular disease. Full article

COVID-19 is known to impair red blood cell (RBC) function, which may affect oxygen transport and disease progression. However, the metabolic consequences of SARS-CoV-2 infection on RBCs and how these changes relate to disease severity and sex differences, have not been systematically explored. Here, we compared RBC metabolomic profiles from healthy controls and individuals with COVID-19 using nuclear magnetic resonance (NMR) to gain insight into disease mechanisms and potential biomarkers. Multivariate and univariate analyses were performed within the men and women cohorts, and clinical factors, including body mass index, comorbidities, and critical clinical status were considered. We found that COVID-19 induces significant metabolic remodeling in RBCs of all patients, including reduced glycolytic and pentose phosphate pathway (PPP) intermediates, consistent with impaired energetic and antioxidant capacity. However, we also observed differences between men and women in the pattern and extent of these changes. Female patients showed changes in metabolites implicated in oxygen release and amino sugar metabolism, including 2,3-BPG, suggesting a distinct metabolic adaptation. By contrast, male patients exhibited a broader set of RBC-specific metabolic disruptions, most evident in severe disease, characterized by decreased amino acid levels, altered glycolytic activity, and weakened antioxidant responses. Overall, these findings identify RBC metabolism as a component of COVID-19 pathophysiology and support its potential as a source of biomarkers. Full article

Post-infectious Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a chronic disease with unresolved pathophysiology and limited diagnostic options. Extracellular vesicles (EVs) carry disease-specific protein and miRNA signatures and may enable improved disease profiling. We aimed to identify novel protein and miRNA markers as potential biomarkers in plasma EVs from female ME/CFS patients, including post-COVID-19 ME/CFS and post-infectious ME/CFS of other origins, compared with healthy controls. EVs were isolated from plasma by size-exclusion chromatography and characterized for number, size, morphology, and surface marker expression. Flow cytometry showed that small EVs strongly expressed tetraspanins, with only minor differences between ME/CFS patients and healthy donors. Proteomic profiling of EVs from ME/CFS patients identified altered cargo proteins, including hemoglobin subunit alpha and insulin-like growth factor-binding protein acid labile subunit compared with healthy controls (n ≤ 10/cohort). Small RNA sequencing followed by qPCR revealed significant downregulation of hsa-let-7b-5p in EVs from post-COVID-19 ME/CFS patients (n = 12) versus healthy controls (n = 15). Reduced hsa-let-7b-5p expression correlated with impaired physical functioning and increased fatigue, pain, and immune activation. These findings indicate that EV cargo differences, particularly hemoglobin subunit alpha and insulin-like growth factor-binding protein acid labile subunit, as well as hsa-let-7b-5p, represent promising candidates for ME/CFS diagnosis and patient stratification. Full article