ACE2 Deficiency Protects Against Heme Protein-Induced Acute Kidney InjuryCroatt, Singh, Grande
et alAm J Physiol Renal Physiol (2025)
Abstract: Angiotensin-converting enzyme 2 (ACE2) exerts countervailing effects on the renin-angiotensin aldosterone system. ACE2 also engages the spike protein of SARS-CoV-2. ACE2 protein has been shown recently to avidly bind heme. We examined the pathobiologic relevance of this heme-binding property of ACE2 by employing the glycerol-induced model of heme protein mediated AKI (HP-AKI) which is characterized by increased kidney heme content. We studied the response of ACE2-wildtype (ACE2+/y) and ACE2-deficient (ACE2-/y) mice to HP-AKI and quantitated kidney and cellular content of heme under relevant conditions. ACE2-deficient mice, compared with ACE2-wildtype mice, were significantly protected against HP-AKI as reflected by filtration markers, less histologic injury, and less expression of apoptosis and ferroptosis markers. ACE2-deficient mice also evinced lesser kidney heme content and a blunted induction of HO-1. HEK293 ACE2-overexpressing cells, compared with HEK293-native, when exposed to heme, retained higher amounts of heme. In HP-AKI, ACE2 expression and activity were reduced, and myoglobin and heme, administered independently, reduced ACE2 expression in the otherwise intact mouse kidney. Finally, with more severe HP-AKI, the protective effect of ACE2 deficiency was attenuated. We conclude that ACE2 deficiency confers protection against HP-AKI. We suggest that this reflects the recently recognized binding of heme to ACE2, such binding serving to facilitate renal entry of heme, a known nephrotoxin. These findings uncover a novel pathway of heme-dependent acute kidney injury. This is the first demonstration of the biologic relevance of chemical binding of heme by ACE2. Finally, we identify heme proteins and heme as novel determinants of ACE2 expression.
Evaluation of the efficacy of the SARS-CoV-2 vaccine additional and booster doses in immunocompromised patients with multiple sclerosis: the COVACiMS studyLadeira, Nobrega, Cerqueira
et alJ Neurol (2025) 272 (4), 288
Abstract: Studies evaluating COVID-19 primary vaccination with two vaccines reported a blunt response in Multiple Sclerosis (MS) patients under anti-CD20 and sphingosine-1-phosphate (S1P) modulators. An extended primary vaccination (EPV) was recommended in immunosuppressed MS patients. Data on the effectiveness of the EPV and subsequent booster dose are limited. A prospective cohort study (n = 270) was conducted to evaluate the humoral and cellular immunogenicity of the EPV scheme in immunocompromised MS patients (i.e., treated with anti-CD20, S1P modulators, natalizumab, teriflunomide, or dimethyl fumarate) vs. regular primary vaccination in non-treated patients - primary course (PC) cohort. The effect of a subsequent booster dose was also assessed - first booster (FB) cohort . The seroconversion rates were 55% and 56% in anti-CD20 and 75% and 67% in S1P modulators group in PC and FB cohort, respectively, and 100% in the remaining groups. A positive SARS-CoV-2 Spike T-spot was observed in 22% of patients under S1P modulators in PC cohort and 67% in FB cohort; the remaining groups had 75% or more. Similar rates of breakthrough infection were observed in both groups vs. controls. Compared to non-treated MS patients, immunosuppressed patients under anti-CD20 and S1P modulators drugs receiving EPV scheme or booster dose still present lower protection rates to SARS-CoV-2.© 2025. The Author(s).
Computational electrostatic engineering of nanobodies for enhanced SARS-CoV-2 receptor binding domain recognitionIqbal, Asim, Khan
et alFront Mol Biosci (2025) 12, 1512788
Abstract: This study presents a novel computational approach for engineering nanobodies (Nbs) for improved interaction with receptor-binding domain (RBD) of the SARS-CoV-2 spike protein. Using Protein Structure Reliability reports, RBD (7VYR_R) was selected and refined for subsequent Nb-RBD interactions. By leveraging electrostatic complementarity (EC) analysis, we engineered and characterized five Electrostatically Complementary Nbs (ECSb1-ECSb5) based on the CeVICA library's SR6c3 Nb. Through targeted modifications in the complementarity-determining regions (CDR) and framework regions (FR), we optimized electrostatic interactions to improve binding affinity and specificity. The engineered Nbs (ECSb3, ECSb4, and ECSb5) demonstrated high binding specificity for AS3, CA1, and CA2 epitopes. Interestingly, ECSb1 and ECSb2 selectively engaged with AS3 and CA1 instead of AS1 and AS2, respectively, due to a preference for residues that conferred superior binding complementarities. Furthermore, ECSbs significantly outperformed SR6c3 Nb in MM/GBSA results, notably, ECSb4 and ECSb3 exhibited superior binding free energies of -182.58 kcal.mol-1 and -119.07 kcal.mol-1, respectively, compared to SR6c3 (-105.50 kcal.mol-1). ECSbs exhibited significantly higher thermostability (100.4-148.3 kcal·mol⁻1) compared to SR6c3 (62.6 kcal·mol⁻1). Similarly, enhanced electrostatic complementarity was also observed for ECSb4-RBD and ECSb3-RBD (0.305 and 0.390, respectively) relative to SR6c3-RBD (0.233). Surface analyses confirmed optimized electrostatic patches and reduced aggregation propensity in the engineered Nb. This integrated EC and structural engineering approach successfully developed engineered Nbs with enhanced binding specificity, increased thermostability, and reduced aggregation, laying the groundwork for novel therapeutic applications targeting the SARS-CoV-2 spike protein.Copyright © 2025 Iqbal, Asim, Khan, Sultan and Ali.
Modulation of RAAS receptors and miRNAs in COVID-19: implications for disease severity, immune response, and potential therapeutic targetsBarreto Fernandes, Pilotto, Cezar
et alBMC Infect Dis (2025) 25 (1), 399
Abstract: The SARS-CoV-2 spike protein interacts with ACE2, a key receptor within the renin-angiotensin-aldosterone system (RAAS), which plays a critical role in maintaining vascular homeostasis, regulating blood pressure, and modulating inflammation. An observational study analyzed the gene expression profiles of RAAS receptors and associated miRNAs in 88 hospitalized COVID-19 patients and 20 healthy controls, comparing the acute and post-acute phases to assess their impact on disease severity and recovery. Our findings revealed an association between reduced MAS1 expression in both advanced age (P = 0.03) and the need for oxygen supplementation (P = 0.04). Additionally, reduced ACE expression was associated with worse mortality outcomes (P = 0.01). Notably, ACE2 and TMPRSS2 expression was significantly decreased (P < 0.0001) in individuals requiring oxygen supplementation and in those with diabetes mellitus during both the acute and post-COVID-19 phases, further highlighting the impact of these conditions on RAAS. The miRNA analysis revealed significant downregulation of miR-200c (P = 0.005), miR-let-7 (P = 0.01), and miR-122 (P = 0.03) in acute-phase COVID-19 patients. This dysregulation contributes to the inflammatory response and highlights the interaction between viral entry and immune regulation. These results underscore the significance of the ACE2/Ang-(1-7)/MAS1 axis in inflammation regulation and suggest that targeting this pathway may have therapeutic potential. Our study provides valuable insights into the molecular mechanisms of COVID-19 pathogenesis and identifies the modulation of RAAS receptors and miRNAs as promising biomarkers for disease severity and potential therapeutic interventions. CLINICAL TRIAL: Not applicable.© 2025. The Author(s).
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