Search Results (63)

Molecular mechanisms underlying the progression from compensated eccentric hypertrophy to heart failure in chronic aortic regurgitation (AR) remain poorly understood. We investigated associated transcriptional changes induced by chronic volume overload in an experimental model of severe AR. AR was induced in male Wistar rats (n = 10) by retrograde aortic valve perforation and compared with age-matched control rats (n = 8). Sixty days after surgery, cardiac remodeling was evaluated by echocardiography, invasive hemodynamics and myocardial gene-expression profiling using RT-qPCR. Chronic AR induced marked left ventricular dilatation and systolic dysfunction, consistent with decompensated eccentric hypertrophy. These functional alterations were accompanied by coordinated transcriptional changes involving pathways related to apoptosis, oxidative balance, metabolic regulation and calcium handling. AR hearts exhibited an increased BAX/BCL2 ratio, together with reduced SOD2 and increased GPX1 expression, suggesting a transcriptional profile consistent with activation of pro-apoptotic and antioxidant responses. Metabolic remodeling was characterized by decreased AMPKα1, PPARγ and GLUT4 expression, together with increased OLR1 and 15-LOX. KLK10 expression was increased. Reduced SERCA2A expression was observed, consistent with transcriptional alterations involving calcium-handling pathways. Chronic AR is associated with marked structural and functional cardiac remodeling accompanied by coordinated transcriptional alterations across multiple pathways implicated in myocardial dysfunction. This provides potential molecular pathways for further investigation. Full article

The kallikrein–kinin system (KKS) and the kallikrein-related peptidase (KLK) family are interconnected proteolytic networks that regulate inflammatory signaling, vascular permeability, extracellular matrix remodeling, and tissue barrier dynamics. Beyond their classical vasoactive and inflammatory functions, accumulating evidence indicates that kinin peptides, including bradykinin, Lys-bradykinin, and their des-Arg⁹ metabolites, together with selected KLKs, modulate cell–cell and cell–extracellular matrix adhesion. Through B1 and B2 kinin receptor activation, the KKS influences endothelial adhesion molecule expression, leukocyte integrin activation, neutrophil trafficking, focal adhesion kinase/Src signaling, cytoskeletal remodeling, and matrix metalloproteinase activity. In parallel, KLKs directly reshape the adhesive microenvironment by cleaving junctional proteins, including E-cadherin and desmosomal components, and extracellular matrix substrates such as fibronectin, laminin, vitronectin, fibrinogen, and collagens. These coordinated actions affect epithelial and endothelial barrier integrity, leukocyte transmigration, angiogenesis, fibrosis, epithelial–mesenchymal transition, tumor cell migration, invasion, and metastatic dissemination. This review critically summarizes current evidence linking KKS and KLK activity to adhesion-dependent processes in inflammation and cancer, emphasizing how proteolytic signaling may either preserve tissue homeostasis or promote pathological barrier disruption depending on cellular context, receptor expression, protease activity, and microenvironmental cues. Understanding these mechanisms may refine the identification of adhesion-related biomarkers and support the development of targeted therapeutic strategies for inflammatory disorders, fibrotic remodeling, and cancer progression. Full article

Factor XII (FXII) is a central mediator at the intersection of coagulation, fibrinolysis, inflammation, and immunity. It is activated upon contact with negatively charged surfaces, triggering the intrinsic coagulation pathway and driving thrombus formation and stabilization. Beyond clotting, FXII contributes to activation of the kallikrein–kinin system, generation of bradykinin, and modulation of inflammatory and immune responses. Congenital FXII deficiency does not increase bleeding risk, highlighting its unique role and making FXII inhibition an attractive strategy for anticoagulation and immune modulation with a potentially superior safety profile. Preclinical studies provide compelling evidence for this concept. In models of ischemic stroke and traumatic brain injury, FXII blockade significantly reduced infarct volume, improved neurological outcomes, and attenuated neuroinflammation without increasing hemorrhage. Similarly, in extracorporeal circulation and vascular stent implantation, FXII inhibition prevented thrombus formation and reduced fibrin deposition, achieving effects comparable to heparin but with markedly lower bleeding risk. Several classes of FXII inhibitors are currently in development, including antisense oligonucleotides, peptides, recombinant proteins, and monoclonal antibodies. Among them, Ixodes ricinus contact phase inhibitor (Ir-CPI) and recombinant human albumin-fused Infestin-4 (rHA-Infestin-4) have demonstrated strong antithrombotic efficacy in animal models. Most notably, garadacimab, a monoclonal anti-FXIIa antibody, has completed phase 3 trials and received regulatory approval for hereditary angioedema (HAE) prophylaxis, where it markedly reduces attack frequency with a favorable safety profile. This review summarizes current knowledge on FXII biology and evaluates its translational potential as a novel target for anticoagulant and anti-inflammatory therapies. Full article

Chronic kidney disease (CKD) has emerged as a pervasive global health concern, for which there are no known curative treatments. Consequently, there is an imperative for the implementation of preventive and kidney-protective strategies. The renal kallikrein–kinin system (KKS) is a vasodilator, anti-inflammatory, and antifibrotic pathway located in the distal nephron, whose decline contributes to hypertension and CKD progression. In this narrative, non-systematic review, a thorough evaluation of both experimental and clinical data was undertaken to ascertain the interactions between dietary potassium, renal KKS activity, and kidney protection. A particular emphasis was placed on animal models of proteinuria, tubulointerstitial damage, and salt-sensitive hypertension, in conjunction with human studies on potassium intake and renal outcomes. A body of experimental evidence suggests a relationship between potassium-rich diets and renal kallikrein synthesis, urinary kallikrein activity, and up-regulated kinin B2 receptor expression. Collectively, these factors have been shown to result in reduced blood pressure, oxidative stress, apoptosis, inflammation, and fibrosis, and these effects are counteracted by B2 receptor blockade. In humans, higher potassium intake has been shown to enhance kallikrein excretion and lower cardiovascular and renal risk, independently of aldosterone. Conversely, low potassium intake has the potential to exacerbate CKD progression. Notwithstanding the concerns that have been raised regarding the potential necessity of increasing potassium intake in cases of advanced CKD, extant evidence would appear to indicate that potassium excretion persists until late disease stages. The activation and preservation of the renal KKS through a potassium-rich diet is a rational, cost-effective strategy for renoprotection. When combined with sodium reduction and nutritional education, this approach has the potential to halt the progression of CKD and enhance cardiovascular health on a population scale. Full article

Background: Familial cold urticarias (FCU) are a group of rare hereditary disorders triggered by exposure to low temperatures. Their pathogenesis is complex, involving mast cell activation, inflammasome dysregulation, and abnormalities of the kallikrein–kinin system. This review aims to summarize the genetic classification, molecular mechanisms, and clinical implications of FCU in diagnosis and management. Methods: Recent literature was reviewed to outline the clinical and molecular characteristics of familial atypical cold urticaria (FACU), familial cold autoinflammatory syndromes (FCAS; including NLRP3-, NLRP12-, NLRC4-, and PLCG2-related subtypes), FXII-associated cold autoinflammatory syndrome (FACAS), and familial predisposed acquired cold urticaria (FP-ACU). Mechanistic clues and diagnostic strategies were analyzed, emphasizing the integration of clinical features with molecular findings. Results: Distinct FCU subtypes exhibit defined genetic bases: gain-of-function mutations in NLRP3, NLRP12, and NLRC4 result in inflammasome hyperactivation; in-frame deletions in PLCG2 lead to temperature-dependent immune signaling dysregulation; and heterozygous F12 variants link contact activation with inflammatory cascades. Combining cold stimulation tests, inflammatory biomarkers, and targeted genetic sequencing enables precise molecular stratification. Conclusions: Molecular subclassification of FCU improves diagnostic accuracy and informs targeted therapy. Future research should focus on the interplay between cold-sensing ion channels, mast cell activation, and inflammasome signaling to advance precision diagnosis and individualized treatment of cold-induced urticarias. Full article

This review reappraises the anti-inflammatory potential of the contact activation system (CAS) in intensive care through an evolutionary lens. The authors propose that coagulation factor XII (FXII) and related components evolved in terrestrial animals as a “foreign-surface sensing–immunothrombosis” module, helping to explain the minimal bleeding phenotype of FXII deficiency and the secondary loss of F12 in marine mammals. CAS shares components with the kallikrein–kinin system (KKS): alpha-coagulation factor XIIa (α-FXIIa) drives coagulation factor XI (FXI) activation to amplify coagulation, whereas betacoagulation factor XIIa (β-FXIIa) activates the KKS to generate bradykinin, promoting vasodilation and vascular leak. Beyond proteolysis, zymogen FXII signals via urokinase-type plasminogen activator receptor (uPAR) to induce neutrophil extracellular trap formation (NETosis), thereby amplifying immunothrombosis. Clinically, the relevance spans sepsis and extracorporeal organ support: pathogens can hijack CAS/KKS to facilitate invasion, and artificial surfaces such as extracorporeal membrane oxygenation (ECMO) circuits chronically trigger contact activation. In animal models, selective inhibition of FXII/FXI prolongs circuit life and attenuates pulmonary edema and inflammation without materially increasing bleeding. The review also catalogs “non-coagulation” roles of CAS members: Activated coagulation factor XI (FXIa) modulates endothelial permeability and smooth-muscle migration, and the FXII heavy chain exhibits direct antimicrobial activity—underscoring CAS as a nexus for coagulation, inflammation, and host defense. Overall, CAS inhibitors may couple “safe anticoagulation” with “cascade-level anti-inflammation,” offering a testable translational path for organ protection in the ICU alongside infection control and informing combined, precision strategies for anticoagulation and anti-inflammatory therapy. Full article

COVID affects around 400 million individuals today with a strong economic impact on the global economy. The list of long COVID symptoms is extremely broad because it is derived from neurological, cardiovascular, respiratory, immune, and renal dysfunctions and damages. We review here these pathophysiological manifestations and the predictors of this multi-organ pathology like the persistence of the virus, altered endothelial function, unrepaired tissue damage, immune dysregulation, and gut dysbiosis. We also discuss the similarities between long COVID and vaccine side effects together with possible common immuno-inflammatory pathways. Since the spike protein is present in SARS-CoV-2 (and its variants) but also produced by the COVID vaccines, its toxicity may also apply to all mRNA or adenoviral DNA vaccines as they are based on the production of a very similar spike protein to the virus. After COVID infection or vaccination, the spike protein can last for months in the body and may interact with ACE2 receptors and mannan-binding lectin (MBL)/mannan-binding lectin serine protease 2 (MASP-2), which are present almost everywhere in the organism. As a result, the spike protein may be able to trigger inflammation in a lot of organs and systems similar to COVID infection. We suggest that three immuno-inflammatory pathways are particularly key and responsible for long COVID and COVID vaccine side effects, as it has been shown for COVID, which may explain in large part their strong similarities: the renin–angiotensin–aldosterone system (RAAS), the kininogen–kinin–kallikrein system (KKS), and the lectin complement pathway. We propose that therapeutic studies should focus on these pathways to propose better cures for both long COVID as well as for COVID vaccine side effects. Full article

The kallikrein–kinin system and its B1 and B2 receptors are key regulators in metabolic disorders such as obesity, diabetes, and insulin resistance. Obesity, a chronic and multifactorial condition often associated with comorbidities like type 2 diabetes and dyslipidemia, remains poorly understood at the metabolic level. The kinin B2 receptor (B2R) is involved in blood pressure regulation and glucose metabolism, promoting glucose uptake in skeletal muscle via bradykinin. Studies in B2R-KO mice demonstrate that the absence of this receptor predisposes animals to glucose intolerance under a high-fat diet and impairs adaptive thermogenesis, indicating a protective role for B2R in metabolic homeostasis and insulin sensitivity. In contrast, the kinin B1 receptor (B1R) is inducible under pathological conditions and is activated by kinin metabolites. Mouse models lacking B1R exhibit improved metabolic profiles, including protection against high-fat diet-induced obesity and insulin resistance, enhanced energy expenditure, and increased leptin sensitivity. B1R inactivation in adipocytes enhances insulin responsiveness and glucose tolerance, supporting its role in the development of insulin resistance. Moreover, B1R deficiency improves energy metabolism and thermogenic responses to adrenergic and cold stimuli, promoting the activation of brown adipose tissue and the browning of white adipose tissue. Collectively, these findings suggest that B1R and B2R represent promising therapeutic targets for the treatment of metabolic disorders. Full article

Endothelial dysfunction plays a central role in COVID-19 pathogenesis, by affecting vascular homeostasis and worsening thromboinflammation. This imbalance may contribute to blood–brain barrier (BBB) disruption, which has been reported in long COVID-19 patients with neurological sequelae. The kallikrein–kinin system (KKS) generates bradykinin (BK), a proinflammatory peptide that induces microvascular leakage via B2R. Under inflammatory conditions, BK is converted to Des-Arg-BK (DABK), which activates B1R, a receptor upregulated in inflamed tissues. DABK is degraded by ACE2, the main SARS-CoV-2 receptor; thus, viral binding and ACE2 downregulation may lead to DABK/B1R imbalance. Here, we investigated these interactions using human brain microvascular endothelial cells (HBMECs), as a model of the BBB. Since endothelial cell lines express low levels of ACE2, HBMECs were modified with an ACE2-carrying pseudovirus. SARS-CoV-2 replication was confirmed by RNA, protein expression, and infectious particles release. Infection upregulated cytokines and endothelial permeability, enhancing viral and leukocyte transmigration. Additionally, viral replication impaired ACE2 function in HBMECs, amplifying the response to DABK, increasing nitric oxide (NO) production, and further disrupting endothelial integrity. Our findings reveal a mechanism by which SARS-CoV-2 impacts the BBB and highlights the ACE2/KKS/B1R axis as a potential contributor to long COVID-19 neurological symptoms. Full article

We used the data from a successful therapeutic assay that used icatibant in patients with hypoxemic COVID-19 pneumonia (the ICAT·COVID trial) to explore pathophysiological mechanisms. We performed concurrent-type, criterion-related validity analyses to assess the discriminative ability of a panel of nine potential serum markers (interleukin 6, ferritin, lactate dehydrogenase, C reactive protein, fibrin fragment D (D-dimer), complement 1 esterase inhibitor (antigenic and functional), complement 4 factor, and lymphocyte count) to predict the clinical milestones. Consistent with previous research, we evidenced a significant relationship between interleukin 6, lactate dehydrogenase and the lymphocyte count, and the clinical events. Furthermore, exposure to icatibant, a bradykinin B2 receptor antagonist (which improved pneumonia and mortality in the aforementioned randomised trial), attenuated this relationship, although this effect faded over time. The results reinforce the key role that the angiotensin-converting enzyme 2 has on COVID-19 pathophysiology as a point of convergence between the renin–angiotensin and kallikrein–kinin systems. This was shown clinically by the successful blocking of inflammatory pathways by icatibant at the bradykinin effector loop level early during the acute hyperinflammatory stage of the disease. Full article

Obesity is a significant global health issue, profoundly affecting metabolic and cardiovascular health and other related chronic conditions. In Chile, the prevalence of obesity is among the highest within the Organisation for Economic Cooperation and Development (OECD) countries, highlighting a critical public health challenge. This narrative review examines current evidence on the independent and potential synergistic roles of omega-3 fatty acids and exercise in managing obesity-related metabolic dysfunction. Omega-3 fatty acids, particularly eicosapentaenoic acid (EPA), have been shown to lower triglyceride levels, enhance lipid metabolism, and modulate inflammation via pathways involving peroxisome proliferator-activated receptors (PPARs) and sterol regulatory element-binding protein-1c (SREBP-1c). Exercise interventions, such as moderate-intensity continuous training (MICT) and high-intensity interval training (HIIT), provide distinct yet complementary metabolic benefits. Specifically, MICT improves body fat distribution and mitochondrial efficiency, whereas HIIT has notable effects on metabolic adaptability and insulin signaling. Additionally, emerging evidence points toward a potential role of the kinin-kallikrein system, particularly kallikrein 7 (KLK7), in obesity-associated insulin resistance. Despite these promising findings, several knowledge gaps persist regarding optimal dosing, intervention timing, population-specific effects, and the exact mechanisms behind the potential synergistic interactions between omega-3 supplementation and structured exercise. This review emphasizes the importance of conducting further research, particularly controlled clinical trials, to clarify these combined interventions’ effectiveness and establish targeted therapeutic strategies tailored to individual metabolic profiles. Full article

Obesity has been the subject of research focused on preventive policies among the young population due to epidemiological studies which have shown devastating figures in recent years in terms of the incidence and prevalence of this condition. A number of previously known biomarkers have proven useful in the early diagnosis of complications associated with obesity, while others remain in the study stage. The intestinal microbiota are also relevant in the secondary prevention of obesity complications, another area that has turned into a hot topic of current research. The primary goal of this review is to highlight markers and mechanisms that can enhance specialists’ understanding of obesity assessment and its systemic complications. Salivary markers have been proven useful in the evaluation of obesity, with the advantage of being low-cost and easy to sample. Another interesting topic is the role of the renin–angiotensin and the kallikrein–kinin systems in obesity-related systemic complications. One well-known fact is the connection between obesity and high blood pressure, which is closely related to these systems. This paper also explores the link between gut microbiota and adiposity, particularly the potential of the Firmicutes/Bacteroidetes ratio as a useful biomarker. Full article

As one of the most common air pollutants, fine particulate matter (PM_2.5) increases the risk of diseases in various systems, including the urinary system. In the present study, we exposed male and female C57BL/6J mice to PM_2.5 for 8 weeks. Examination of renal function indices, including creatinine (CRE), blood urea nitrogen (BUN), uric acid (UA), and urinary microalbumin, indicated that the kidneys of female mice, not male mice, underwent early renal injury, exhibiting glomerular hyperfiltration. Meanwhile, pathological staining showed that the kidneys of female mice exhibited enlarged glomerulus that filled the entire Bowman’s capsule in the female mice. Afterward, we explored the potential causes and mechanisms of glomerular hyperfiltration. Variations in mRNA levels of key genes involved in the renin–angiotensin system (RAS) and kallikrein–kinin system (KKS) demonstrated that PM_2.5 led to elevated glomerular capillary hydrostatic pressure in female mice by disturbing the balance between the RAS and KKS, which in turn increased the glomerular filtration rate (GFR). In addition, we found that PM_2.5 increased blood glucose levels in the females, which enhanced tubular reabsorption of glucose, attenuated macular dense sensory signaling, induced renal hypoxia, and affected adenosine triphosphate (ATP) synthesis, thus attenuating tubuloglomerular feedback (TGF)-induced afferent arteriolar constriction and leading to glomerular hyperfiltration. In conclusion, this study indicated that PM_2.5 induced glomerular hyperfiltration in female mice by affecting RAS/KKS imbalances, as well as the regulation of TGF; innovatively unveiled the association between PM_2.5 subchronic exposure and early kidney injury and its gender dependence; enriched the toxicological evidence of PM_2.5 and confirmed the importance of reducing ambient PM_2.5 concentrations. Full article

Background: Although more than four years have passed since the pandemic began, SARS-CoV-2 continues to be of concern. Therefore, research into the underlying mechanisms that contribute to the development of the disease, especially in more severe forms, remains a priority. Sustained activation of the complement (CS), contact (CAS), and fibrinolytic and kinin–kallikrein systems (KKS) has been shown to play a central role in the pathogenesis of the disease. Since the C1 esterase inhibitor (C1-INH) is a potent inhibitor of all these systems, its role in the disease has been investigated, but some issues remained unresolved. Methods: We evaluated the impact of C1-INH and KKS on disease progression in a cohort of 45 COVID-19 patients divided into groups according to disease severity. We measured plasma levels of total and functional C1-INH and its complexes with kallikrein (PKa), reflecting KKS activation and kallikrein spontaneous activity. Results: We observed increased total and functional plasma concentrations of C1-INH in COVID-19 patients. A direct correlation (positive Spearman’s r) was observed between C1-INH levels, especially functional C1-INH, and the severity of the disease. Moreover, a significant reduction in the ratio of functional over total C1-INH was evident in patients exhibiting mild to intermediate clinical severity but not in critically ill patients. Accordingly, activation of the KKS, assessed as an increase in PKa:C1-INH complexes, was explicitly observed in the mild categories. Conclusions: Our study’s findings on the consumption of C1-INH and the activation of the KKS in the less severe stages of COVID-19 but not in the critical stage suggest a potential role for C1-INH in containing disease severity. These results underscore the importance of C1-INH in the early phases of the disease and its potential implications in COVID-19 progression and/or long-term effects. Full article

Toxicofera reptile venoms are composed of several toxins, including serine proteases. These proteases are glycosylated enzymes that affect the prey’s hemostatic system. Their actions extend across the coagulation cascade, the kallikrein–kinin system, and platelet activation. Despite their specificity for different substrates, these enzymes are homologous across all toxicoferans and display high sequence similarity. The aim of this review is to compile decades of knowledge about venom serine proteases, showing the diversity of biochemically and biophysically characterized enzymes, their structural characteristics, advances in understanding their origin and evolution, as well as methods of obtaining enzymes and their biotechnological applications. Full article